JP7829403B2 - Salt, acid generator, resist composition, and method for producing resist patterns - Google Patents

Description

This invention relates to salts, acid generators, resist compositions, and methods for producing resist patterns.

Patent Document 1 describes a salt represented by the following formula and a resist composition containing the salt as an acid generator.
Patent Document 2 describes a salt represented by the following formula and a resist composition containing the salt as an acid generator.
Patent Document 3 describes a salt represented by the following formula and a resist composition containing the salt as an acid generator.
Patent Document 4 describes a salt represented by the following formula and a resist composition containing the salt as an acid generator.

Japanese Patent Publication No. 2017-155038 Japanese Patent Publication No. 2018-024642 Japanese Patent Publication No. 2018-005224 Japanese Patent Publication No. 2018-025789

The present invention aims to provide a salt that forms a resist pattern with better CD uniformity (CDU) than a resist pattern formed from a resist composition containing the above-mentioned salt.

This invention includes the following inventions.
[1] An acid generator containing a salt represented by formula (I).
[In formula (I),
^Q1 and ^Q2 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
^R11 and ^R12 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
z represents an integer from 0 to 6, and when z is 2 or greater, multiple ^R11 and ^R12 may be the same or different from each other.
^X1 represents *-CO-O-, *-O-CO-, *-O-CO-O-, or *-O-, where * represents a binding site with C( ^R11 )( ^R12 ) or C( ^Q1 )( ^Q2 ).
^L1 represents a hydrocarbon group having 1 to 60 carbon atoms, which may have a single bond or substituents, and the _-CH2- contained in the hydrocarbon group may be replaced with -O-, -S-, -SO2-, or _-CO- .
X ^a and X ^b each independently represent -O- or -S-.
Ring W1 represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
Ring W represents a cyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
^R1 and ^R2 each independently represent a halogen atom, a hydroxyl group, a C1-C12 haloalkyl group, or a C1-C12 alkyl group, and the _-CH2- contained in the haloalkyl group and the alkyl group may be replaced with -O- or -CO-.
R ³ represents *-O-R ¹⁰ , *-O-CO-R ¹⁰ , *-CO-O-R ¹⁰ , *-O-CO-O-R ¹⁰ , *-O-L ¹⁰ -CO-O-R ¹⁰ , or *-O-L ¹⁰ -O-CO-R ¹⁰ , where * represents the bonding site with ring W.
^L10 represents an alkanediyl group with 1 to 6 carbon atoms.
R ¹⁰ represents a C1-C36 hydrocarbon group having an iodine atom or a C1-C12 iodate alkyl group, or a C3-C36 cyclic hydrocarbon group having a fluorine atom or a C1-C12 fluoride alkyl group, wherein the hydrocarbon group and the cyclic hydrocarbon group may have substituents, and the _-CH2- contained in the hydrocarbon group and the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
m1 represents an integer between 0 and 6, and when m1 is 2 or greater, multiple ^R1s may be the same or different from each other.
m² represents an integer between 0 and 6, and when m² is 2 or greater, multiple ^R² values may be the same or different from each other.
m3 represents an integer from 1 to 6, and when m3 is 2 or greater, multiple ^R3s may be the same or different from each other.
Z ⁺ represents an organic cation.
[2] ^L1 is a single bond, * ^-L2- or * ^-L2 - ^X3 - ^L3- ( ^L2 represents a chain hydrocarbon group having 1 to 10 carbon atoms which may have substituents, a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, or a group formed by a combination of a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents and a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. * represents the bonding site with ^X1 . ^X3 represents **-CO-O-, **-O-CO-, **-O-CO-O- or **-O-, and ** represents the bonding site with ^L2 . The acid generator according to [1], wherein ³ represents a chain hydrocarbon group having 1 to 8 carbon atoms, which may have single bonds or substituents, and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-.
[3] The acid generator according to [1] or [2], wherein ring W1 is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), or a group derived from a ring represented by formula (w1-15).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), and (w1-15),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position.
[4] The acid generator according to any one of [1] to [3], wherein ring W is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), a group derived from a ring represented by formula (w1-12), a group derived from a ring represented by formula (w1-22), a group derived from a ring represented by formula (w1-23), or a group derived from a ring represented by formula (w1-24).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), (w1-12), (w1-22), (w1-23), and (w1-24),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position.
[5] An acid generator according to any one of [1] to [4], wherein R ¹⁰ is a chain hydrocarbon group having 1 to 6 carbon atoms having an iodine atom, a group combining a cycloaliphatic hydrocarbon group having 3 to 12 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a group combining an aromatic hydrocarbon group having 6 to 14 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a cycloaliphatic hydrocarbon group having a fluorine atom, an iodine atom or a trifluoromethyl group, or an aromatic hydrocarbon group having 6 to 14 carbon atoms having a fluorine atom, an iodine atom or a trifluoromethyl group (the chain hydrocarbon group, the cycloaliphatic hydrocarbon group and the aromatic hydrocarbon group may have substituents, and the _-CH2- contained in the chain hydrocarbon group and the cycloaliphatic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- ).
A resist composition containing an acid generator according to any one of [6] [1] to [5] and a resin having an acid-unstable group.
[7] The resist composition according to [6], wherein the resin having an acid-unstable group comprises at least one selected from the group consisting of a structural unit represented by formula (a1-0), a structural unit represented by formula (a1-1), and a structural unit represented by formula (a1-2).
[In formulas (a1-0), (a1-1), and (a1-2),
L ^a01 , L ^a1 , and L ^a2 each independently represent -O- or *-O-(CH ₂ ) _k1 -CO-O-, where k1 is an integer from 1 to 7, and * represents the bond site with -CO-.
^Ra01 , ^Ra4 , and ^Ra5 each independently represent a hydrogen atom, a halogen atom, or a C1-C6 alkyl group which may contain a halogen atom.
R ^a02 , R ^a03 , and R ^a04 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a combination thereof.
^Ra6 and ^Ra7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group formed by a combination of these.
m1 represents an integer between 0 and 14.
n1 represents an integer between 0 and 10.
n1' represents an integer between 0 and 3.
[8] The resist composition according to [6] or [7], wherein the resin having an acid-unstable group comprises a structural unit represented by formula (a2-A).
[In formula (a2-A),
R ^a50 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
R ^a51 represents a halogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C12 alkoxyalkyl group, a C2-C12 alkoxyalkoxy group, a C2-C4 alkylcarbonyl group, a C2-C4 alkylcarbonyloxy group, an acryloyloxy group, or a methacryloyloxy group.
A ^a50 represents a single bond or ^* -X ^a51 - (A ^a52 -X ^a52 ) _nb -, where * represents the bonding site with the carbon atom to which -R ^a50 is bonded.
A ^a52 represents an alkanediyl group with 1 to 6 carbon atoms.
X ^a51 and X ^a52 independently represent -O-, -CO-O-, or -O-CO-, respectively.
nb represents either 0 or 1.
mb represents an integer between 0 and 4. If mb is an integer greater than or equal to 2, multiple R ^a51s may be identical or different from each other.
[9] The resist composition according to any one of [6] to [8], further comprising a salt that generates an acid with a lower acidity than the acid generated from the acid generator.
[10] (1) A step of applying the resist composition described in any of [6] to [9] onto a substrate,
(2) A step of drying the coated composition to form a composition layer,
(3) Exposure step of the composition layer,
A method for manufacturing a resist pattern, comprising the steps of (4) heating the composition layer after exposure and (5) developing the composition layer after heating.
[11] A salt represented by formula (I).
[In formula (I),
^Q1 and ^Q2 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
^R11 and ^R12 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
z represents an integer from 0 to 6, and when z is 2 or greater, multiple ^R11 and ^R12 may be the same or different from each other.
^X1 represents *-CO-O-, *-O-CO-, *-O-CO-O-, or *-O-, where * represents a binding site with C( ^R11 )( ^R12 ) or C( ^Q1 )( ^Q2 ).
^L1 represents a hydrocarbon group having 1 to 60 carbon atoms, which may have a single bond or substituents, and the _-CH2- contained in the hydrocarbon group may be replaced with -O-, -S-, -SO2-, or _-CO- .
X ^a and X ^b each independently represent -O- or -S-.
Ring W1 represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
Ring W represents a cyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
^R1 and ^R2 each independently represent a halogen atom, a hydroxyl group, a C1-C12 haloalkyl group, or a C1-C12 alkyl group, and the _-CH2- contained in the haloalkyl group and the alkyl group may be replaced with -O- or -CO-.
R ³ represents *-O-R ¹⁰ , *-O-CO-R ¹⁰ , *-CO-O-R ¹⁰ , *-O-CO-O-R ¹⁰ , *-O-L ¹⁰ -CO-O-R ¹⁰ , or *-O-L ¹⁰ -O-CO-R ¹⁰ , where * represents the bonding site with ring W.
^L10 represents an alkanediyl group with 1 to 6 carbon atoms.
R ¹⁰ represents a C1-C36 hydrocarbon group having an iodine atom or a C1-C12 iodate alkyl group, or a C3-C36 cyclic hydrocarbon group having a fluorine atom or a C1-C12 fluoride alkyl group, wherein the hydrocarbon group and the cyclic hydrocarbon group may have substituents, and the _-CH2- contained in the hydrocarbon group and the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
m1 represents an integer between 0 and 6, and when m1 is 2 or greater, multiple ^R1s may be the same or different from each other.
m² represents an integer between 0 and 6, and when m² is 2 or greater, multiple ^R² values may be the same or different from each other.
m3 represents an integer from 1 to 6, and when m3 is 2 or greater, multiple ^R3s may be the same or different from each other.
Z ⁺ represents an organic cation.
[12] ^L1 is a single bond, * ^-L2- or * ^-L2 - ^X3 - ^L3- ( ^L2 represents a chain hydrocarbon group having 1 to 10 carbon atoms which may have substituents, a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, or a group formed by a combination of a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents and a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. * represents the bonding site with ^X1 . ^X3 represents **-CO-O-, **-O-CO-, **-O-CO-O- or **-O-, and ** represents the bonding site with ^L2 . The salt according to [11], wherein ³ represents a chain hydrocarbon group having 1 to 8 carbon atoms, which may have single bonds or substituents, and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-.
[13] The salt according to [11] or [12], wherein ring W1 is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), or a group derived from a ring represented by formula (w1-15).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), and (w1-15),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position.
[14] The salt according to any one of [11] to [13], wherein ring W is a group derived from the ring represented by formula (w1-1), a group derived from the ring represented by formula (w1-2), a group derived from the ring represented by formula (w1-3), a group derived from the ring represented by formula (w1-6), a group derived from the ring represented by formula (w1-12), a group derived from the ring represented by formula (w1-22), a group derived from the ring represented by formula (w1-23), or a group derived from the ring represented by formula (w1-24).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), (w1-12), (w1-22), (w1-23), and (w1-24),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position.
[15] The salt according to any one of [11] to [14], wherein R ¹⁰ is a chain hydrocarbon group having 1 to 6 carbon atoms having an iodine atom, a group combining a cycloaliphatic hydrocarbon group having 3 to 12 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a group combining an aromatic hydrocarbon group having 6 to 14 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a cycloaliphatic hydrocarbon group having a fluorine atom, an iodine atom or a trifluoromethyl group, or an aromatic hydrocarbon group having 6 to 14 carbon atoms having a fluorine atom, an iodine atom or a trifluoromethyl group (the chain hydrocarbon group, the cycloaliphatic hydrocarbon group and the aromatic hydrocarbon group may have substituents, and the _-CH2- contained in the chain hydrocarbon group and the cycloaliphatic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- ).

By using a resist composition containing the salt of the present invention, resist patterns can be manufactured with good CD uniformity (CDU).

In this specification, "(meth)acrylic monomer" means "at least one of acrylic monomers and methacrylic monomers." The notations "(meth)acrylate" and "(meth)acrylic acid" have the same meaning. For groups described herein that can take both linear and branched structures, either is acceptable. When the _-CH2- contained in hydrocarbon groups, etc., is replaced by -O-, -S-, -CO- or _-SO2- , the same example shall apply to each group. "Combined group" means a group formed by bonding two or more of the exemplified groups, and the valences of these groups may be appropriately changed depending on the bonding configuration. "Derived from" or "induced from" means that the polymerizable C=C bond contained in the molecule becomes a -C-C- group (single bond) through polymerization. If stereoisomers exist, all stereoisomers are included.

[Salt represented by formula (I)]
This invention relates to a salt represented by formula (I) (hereinafter sometimes referred to as "salt (I)").
In salts (I), the side with a negative charge is sometimes called an "anion (I)," and the side with a positive charge is sometimes called a "cation (I)."
[In the formula, all signs have the same meaning as described above.]

In formula (I), examples of perfluoroalkyl groups for ^Q1 , ^Q2 , ^R11 , and ^R12 include trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, and perfluorohexyl groups. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 4, and more preferably 1 to 3.
Examples of alkyl groups for ^Q1 , ^Q2 , ^R11 , and ^R12 include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and hexyl groups. The number of carbon atoms in the alkyl group is preferably 1 to 4, and more preferably 1 to 3.
^Q1 and ^Q2 are preferably at least one of which is a fluorine atom or a perfluoroalkyl group, more preferably independently a trifluoromethyl group or a fluorine atom, and even more preferably both are fluorine atoms.
^R11 and ^R12 are each independently preferably a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and more preferably a hydrogen atom or a trifluoromethyl group.
z is preferably an integer from 0 to 4, more preferably an integer from 0 to 3, and even more preferably 0 or 1.
^X1 is preferably *-CO-O-, *-O-CO-O-, or *-O-CO-, and more preferably *-CO-O- or *-O-CO-O- (where * represents a bonding site with C( ^R11 )( ^R12 ) or C( ^Q1 )( ^Q2 )).

Examples of hydrocarbon groups in ^L1 include cyclic hydrocarbon groups such as chain hydrocarbon groups, monocyclic or polycyclic (including spiro rings, fused rings, or cross-linking rings) alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. Groups formed by combining two or more of these groups (for example, hydrocarbon groups formed from an alicyclic hydrocarbon group or an aromatic hydrocarbon group and a chain hydrocarbon group) are also acceptable. The number of carbon atoms in the hydrocarbon group is preferably 1 to 54, more preferably 1 to 48, even more preferably 1 to 42, even more preferably 1 to 38, even more preferably 1 to 36, even more preferably 1 to 32, and even more preferably 1 to 28.
Examples of chain-like hydrocarbon groups include divalent chain-like hydrocarbon groups such as alkanediyl groups, alkenediyl groups, and alkynediyl groups.
Examples of alkanediyl groups include linear alkanediyl groups such as methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group and heptadecane-1,17-diyl group, and Examples of branched alkanediyl groups include ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.
Examples of alkenediyl groups include ethendiyl group, propendiyl group, isopropendiyl group, butendiyl group, isobutendiyl group, tert-butendiyl group, pentendiyl group, hexendiyl group, heptendiyl group, octendiyl group, isooctenediyl group, and nonenindiyl group.
Examples of alkynediyl groups include ethindiyl group, propindiyl group, isopropindiyl group, butindiyl group, isobutindiyl group, tert-butindiyl group, pentindiyl group, hexindiyl group, octindiyl group, and nonindiyl group.
The number of carbon atoms in the chain-like hydrocarbon group is preferably 1 to 18, more preferably 1 to 12, even more preferably 1 to 10, even more preferably 1 to 8, even more preferably 1 to 7, even more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 4.

Examples of monocyclic or polycyclic alicyclic hydrocarbon groups include the following alicyclic hydrocarbon groups. The bonding site can be at any position.
Examples include divalent alicyclic hydrocarbon groups such as cycloalkanediyl groups.
Specifically, monocyclic alicyclic hydrocarbon groups such as cycloalkanediyl groups like cyclobutane-1,3-diyl, cyclopentane-1,3-diyl, cyclohexane-1,4-diyl, and cyclooctane-1,5-diyl, and polycyclic alicyclic hydrocarbon groups such as norbornane-1,4-diyl, norbornane-2,5-diyl, adamantane-1,5-diyl, adamantane-2,6-diyl, decahydronaphthalenediyl, and bicyclo[3.3.0]octanediyl.
Examples include cycloalkyl groups such as spirocyclohexane-1,2'cyclopentane and spiroadamantane-2,3'-cyclopentane, and spiro rings having a cycloalkyl group attached by a spiro to a norbonyl group or an adamantyl group.
The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 36, more preferably 3 to 24, even more preferably 3 to 20, even more preferably 3 to 18, even more preferably 3 to 16, and even more preferably 3 to 12.
Examples of aromatic hydrocarbon groups include divalent aromatic hydrocarbon groups such as arenediyl groups.
Specifically, examples include aromatic hydrocarbon groups such as phenylene groups, naphthylene groups, anthrylene groups, biphenylene groups, and phenanthrylene groups.
The number of carbon atoms in the aromatic hydrocarbon group is preferably 3 to 36, more preferably 6 to 24, even more preferably 6 to 20, even more preferably 6 to 18, even more preferably 6 to 14, and even more preferably 6 to 10.

Examples of groups formed by combining two or more types include groups formed by combining an alicyclic hydrocarbon group and a chain hydrocarbon group, groups formed by combining an aromatic hydrocarbon group and a chain hydrocarbon group, groups formed by combining an alicyclic hydrocarbon group and an aromatic hydrocarbon group, and groups formed by combining an alicyclic hydrocarbon group, a chain hydrocarbon group and an aromatic hydrocarbon group. In the combinations, two or more types of alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and chain hydrocarbon groups may be combined. Furthermore, any of these groups may be bonded to ^X1 .
Examples of groups combining alicyclic hydrocarbon groups and chain hydrocarbon groups include groups in which an alicyclic hydrocarbon group is bonded to a chain hydrocarbon group (e.g., *-chain hydrocarbon group-alicyclic hydrocarbon group-, etc.), groups in which a chain hydrocarbon group is bonded to an alicyclic hydrocarbon group (e.g., *-alicyclic hydrocarbon group-chain hydrocarbon group-, etc.), groups in which an alicyclic hydrocarbon group and a chain hydrocarbon group are bonded to a chain hydrocarbon group (e.g., *-chain hydrocarbon group-alicyclic hydrocarbon group-chain hydrocarbon group-, etc.), and groups in which an alicyclic hydrocarbon group and a chain hydrocarbon group are bonded to an alicyclic hydrocarbon group. Examples include groups to which a hydrogenated group is bonded (e.g., *-alicyclic hydrocarbon group-chain hydrocarbon group-alicyclic hydrocarbon group-, etc.), groups to which a chain hydrocarbon group is bonded with an alicyclic hydrocarbon group, a chain hydrocarbon group and another alicyclic hydrocarbon group (e.g., *-chain hydrocarbon group-alicyclic hydrocarbon group-chain hydrocarbon group-alicyclic hydrocarbon group-, etc.), and groups to which a chain hydrocarbon group is bonded with an alicyclic hydrocarbon group and another alicyclic hydrocarbon group (e.g., *-alicyclic hydrocarbon group-chain hydrocarbon group-alicyclic hydrocarbon group-chain hydrocarbon group-, etc.).
Examples of groups combining aromatic hydrocarbon groups and chain hydrocarbon groups include groups in which an aromatic hydrocarbon group is bonded to a chain hydrocarbon group (e.g., *-chain hydrocarbon group-aromatic hydrocarbon group-, etc.), groups in which a chain hydrocarbon group is bonded to an aromatic hydrocarbon group (e.g., *-aromatic hydrocarbon group-chain hydrocarbon group-, etc.), and groups in which an aromatic hydrocarbon group and a chain hydrocarbon group are bonded to a chain hydrocarbon group (e.g., *-chain hydrocarbon group-aromatic hydrocarbon group-chain hydrocarbon group-, etc.).
Groups combining alicyclic hydrocarbon groups and aromatic hydrocarbon groups include groups in which an aromatic hydrocarbon group is bonded to an alicyclic hydrocarbon group (e.g., *-alicyclic hydrocarbon group-aromatic hydrocarbon group-, etc.), groups in which an alicyclic hydrocarbon group is bonded to an aromatic hydrocarbon group (e.g., *-aromatic hydrocarbon group-alicyclic hydrocarbon group-, etc.), and groups in which an alicyclic hydrocarbon group and an aromatic hydrocarbon group are condensed (e.g., the following groups (the bonding site is at any position)).
Examples of groups combining alicyclic hydrocarbon groups, chain hydrocarbon groups, and aromatic hydrocarbon groups include groups in which aromatic hydrocarbon groups and chain hydrocarbon groups are bonded to an alicyclic hydrocarbon group (for example, *-alicyclic hydrocarbon group-aromatic hydrocarbon group-chain hydrocarbon group-, etc.) and groups in which alicyclic hydrocarbon groups and chain hydrocarbon groups are bonded to an aromatic hydrocarbon group (for example, *-aromatic hydrocarbon group-alicyclic hydrocarbon group-chain hydrocarbon group-, etc.).
* indicates the connection site with ^X1 .

The _-CH2- contained in the hydrocarbon group having 1 to 60 carbon atoms in ^L1 may be replaced with -O-, -S-, _-SO2- , or -CO-.
If the _-CH2- contained in a hydrocarbon group with 1 to 60 carbon atoms in ^L1 is replaced with -O-, -S-, _-SO2- , or -CO-, the number of carbon atoms before the replacement shall be considered the number of carbon atoms in the hydrocarbon group.
Groups in which the _-CH2- contained in a hydrocarbon group is replaced with -O-, -S-, _-SO2- , or -CO- include: hydroxyl group (a group in which the _-CH2- contained in a methyl group is replaced with -O-), carboxyl group (a group in which the _-CH2 - _CH2- contained in an ethyl group is replaced with -O-CO-), thiol group (a group in which the _-CH2- contained in a methyl group is replaced with -S-), alkoxy group (a group in which the _-CH2- at any position in an alkyl group is replaced with -O-), alkylthio group (a group in which the _-CH2- at any position in an alkyl group is replaced with -S-), alkoxycarbonyl group (a group in which the _-CH2 - _CH2- at any position in an alkyl group is replaced with -O-CO-), and alkylsulfonyl group (a group in which the _-CH2- at any position in an alkyl group is replaced with _{-SO2- ال ​ ​ ​ ​ ​ ​ ​ ​} Examples include groups in which - is replaced by -CO-), alkanediylcarbonyloxy groups (groups in which _-CH2 - _CH2- at any position in an alkanediyl group is replaced by -CO-O-), alkanediylsulfonyl groups (groups in which _-CH2- at any position in an alkanediyl group is replaced by _-SO2- ), alkanediylthio groups (groups in which _-CH2- at any position in an alkanediyl group is replaced by -S-), cycloalkoxy groups, cycloalkylalkoxy groups, alkoxycarbonyloxy groups, aromatic hydrocarbon group-carbonyloxy groups, aromatic hydrocarbon group-carbonyl groups, aromatic hydrocarbon group-oxy groups, and groups that combine two or more of these groups.

Examples of alkoxy groups include alkoxy groups having 1 to 17 carbon atoms, such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, and undecyloxy groups. The number of carbon atoms in the alkoxy group is preferably 1 to 11, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
Examples of alkylthio groups include alkylthio groups having 1 to 17 carbon atoms, such as methylthio groups, ethylthio groups, propylthio groups, and butylthio groups. The number of carbon atoms in the alkylthio group is preferably 1 to 11, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
Alkoxycarbonyl groups, alkylcarbonyl groups, and alkylcarbonyloxy groups represent groups in which a carbonyl group or carbonyloxy group is bonded to an alkyl group or alkoxy group as described above.
Examples of alkoxycarbonyl groups include alkoxycarbonyl groups having 2 to 17 carbon atoms, such as methoxycarbonyl groups, ethoxycarbonyl groups, and butoxycarbonyl groups. Examples of alkylcarbonyl groups include alkylcarbonyl groups having 2 to 18 carbon atoms, such as acetyl groups, propionyl groups, and butyryl groups. Examples of alkylcarbonyloxy groups include alkylcarbonyloxy groups having 2 to 17 carbon atoms, such as acetyloxy groups, propionyloxy groups, and butyryloxy groups. The number of carbon atoms in the alkoxycarbonyl group is preferably 2 to 11, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3. The number of carbon atoms in the alkylcarbonyl group is preferably 2 to 12, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3. The number of carbon atoms in the alkylcarbonyloxy group is preferably 2 to 11, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3.
Examples of alkylsulfonyl groups include alkylsulfonyl groups having 1 to 17 carbon atoms, such as methylsulfonyl groups, ethylsulfonyl groups, and propylsulfonyl groups. The number of carbon atoms in the alkylsulfonyl group is preferably 1 to 11, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
Examples of alkanediyloxy groups include alkanediyloxy groups having 1 to 17 carbon atoms, such as methyleneoxy, ethyleneoxy, propanediyloxy, butanediyloxy, and pentanediyloxy groups. The number of carbon atoms in the alkanediyloxy group is preferably 1 to 11, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
Examples of alkanediyloxycarbonyl groups include alkanediyloxycarbonyl groups having 2 to 17 carbon atoms, such as methyleneoxycarbonyl groups, ethyleneoxycarbonyl groups, propanediyloxycarbonyl groups, and butanediyloxycarbonyl groups. Examples of alkanediylcarbonyl groups include alkanediylcarbonyl groups having 2 to 18 carbon atoms, such as methylenecarbonyl groups, ethylenecarbonyl groups, propanediylcarbonyl groups, butanediylcarbonyl groups, and pentanediylcarbonyl groups. Examples of alkanediylcarbonyloxy groups include alkanediylcarbonyloxy groups having 2 to 17 carbon atoms, such as methylenecarbonyloxy groups, ethylenecarbonyloxy groups, propanediylcarbonyloxy groups, and butanediylcarbonyloxy groups. The number of carbon atoms in the alkanediyloxycarbonyl group is preferably 2 to 11, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3. The number of carbon atoms in the alkanediylcarbonyl group is preferably 2 to 12, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3. The number of carbon atoms in the alkanediylcarbonyloxy group is preferably 2 to 11, more preferably 2 to 6, even more preferably 2 to 4, and even more preferably 2 or 3.
Examples of alkanediylthio groups include alkanediylthio groups having 1 to 17 carbon atoms, such as methylenethio groups, ethylenethio groups, and propylenethio groups. The number of carbon atoms in the alkanediylthio group is preferably 1 to 11, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
Examples of alkanediylsulfonyl groups include alkanediylsulfonyl groups having 1 to 17 carbon atoms, such as methylenesulfonyl groups, ethylenesulfonyl groups, and propylenesulfonyl groups. The number of carbon atoms in the alkanediylsulfonyl group is preferably 1 to 11, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.

Examples of cycloalkoxy groups include cycloalkoxy groups having 3 to 17 carbon atoms, such as the cyclohexyloxy group. Examples of cycloalkylalkoxy groups include cycloalkylalkoxy groups having 4 to 17 carbon atoms, such as the cyclohexylmethoxy group. Examples of alkoxycarbonyloxy groups include alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as the butoxycarbonyloxy group. Examples of aromatic hydrocarbon group-carbonyloxy groups include aromatic hydrocarbon group-carbonyloxy groups having 7 to 17 carbon atoms, such as the benzoyloxy group. Examples of aromatic hydrocarbon group-carbonyl groups include aromatic hydrocarbon group-carbonyl groups having 7 to 17 carbon atoms, such as the benzoyl group. Examples of aromatic hydrocarbon group-oxy groups include aromatic hydrocarbon group-oxy groups having 6 to 16 carbon atoms, such as the phenyloxy group.

Furthermore, the following groups are examples of groups in which the _-CH2- contained in an alicyclic hydrocarbon group is replaced with -O-, -S-, -CO-, or _-SO2- . The -O- or -CO- in the groups shown below may be replaced with -S- or _-SO2- , respectively. The bonding site can be at any position.
The following groups are examples of groups in which the _-CH2- contained in the combined group is replaced with -O-, -S-, -CO-, or _-SO2- . The bonding site can be at any position.

Substituents that ^L1 may have include hydroxyl groups, carboxyl groups, halogen atoms, cyano groups, C1-C12 alkyl groups, C1-C12 alkoxy groups, C2-C13 alkoxycarbonyl groups, C2-C13 alkylcarbonyl groups, C2-C13 alkylcarbonyloxy groups, or groups combining these.
Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.
Examples of alkyl groups having 1 to 12 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, and nonyl groups.
Examples of alkoxy groups having 1 to 12 carbon atoms include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, undecyloxy, and dodecyloxy groups.
The alkoxycarbonyl group having 2 to 13 carbon atoms, the alkylcarbonyl group having 2 to 13 carbon atoms, and the alkylcarbonyloxy group having 2 to 13 carbon atoms represent groups in which a carbonyl group or carbonyloxy group is bonded to the alkyl group or alkoxy group described above.
Examples of alkoxycarbonyl groups having 2 to 13 carbon atoms include methoxycarbonyl, ethoxycarbonyl, and butoxycarbonyl groups. Examples of alkylcarbonyl groups having 2 to 13 carbon atoms include acetyl, propionyl, and butyryl groups. Examples of alkylcarbonyloxy groups having 2 to 13 carbon atoms include acetyloxy, propionyloxy, and butyryloxy groups.
The substituent is preferably an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom, or a group consisting of a combination thereof.

^L1 is preferably a single bond, a chain hydrocarbon group having 1 to 10 carbon atoms which may have substituents (however, the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-), a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents (however, the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- ), or a group formed by combining a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents and a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents (however, the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, _-SO2- or -CO-), and is preferably a single bond, a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents (however, the -CH2- contained in the chain hydrocarbon group may be replaced with -O-, -S-, -SO2- or -CO-). ₂ - may be replaced with -O- or -CO-. ), a cyclic hydrocarbon group having 3 to 20 carbon atoms which may have substituents (however, the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or -SO2-), or a group formed by combining a chain hydrocarbon group having 1 to 6 carbon atoms which may have substituents and a cyclic hydrocarbon group having 3 to ₂₀ carbon atoms which may have substituents (however, the -CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -SO2- or -CO-), more preferably a single bond, a chain hydrocarbon group having 1 to 7 carbon atoms which may have substituents (however, the _-CH2- contained in the chain hydrocarbon group may be replaced with -O-, -S-, _-SO2- or -CO-), a single bond, a chain hydrocarbon group having 1 to 7 carbon atoms which may have substituents (however, the _-CH2- contained in the chain hydrocarbon group may be replaced with -O-, -S-, -SO2- or -CO-), It is more preferable that the group is a cyclic hydrocarbon group having 3 to 18 carbon atoms that may have substituents (however, the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O- or -CO-), or a group formed by combining a chain hydrocarbon group having 1 to 5 carbon atoms that may have substituents and a cyclic hydrocarbon group having 3 to 18 carbon atoms that may have substituents (however, the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O- or -CO-).

Furthermore, ^L1 represents a single bond, * ^-L2- or * ^-L2 - ^X3 - ^L3- ( ^L2 represents a chain hydrocarbon group having 1 to 10 carbon atoms which may have substituents, a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, or a group formed by a combination of a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents and a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. * represents the bonding site with ^X1 . ^X3 represents **-CO-O-, **-O-CO-, **-O-CO-O- or **-O-, and ** represents the bonding site with ^L2 . ³ represents a chain hydrocarbon group having 1 to 8 carbon atoms, which may have single bonds or substituents, and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-.
Examples of combinations of chain hydrocarbon groups and cyclic hydrocarbon groups include: *-chain hydrocarbon group-alicyclic hydrocarbon group or aromatic hydrocarbon group-, *-alicyclic hydrocarbon group or aromatic hydrocarbon group-chain hydrocarbon group-, *-chain hydrocarbon group-alicyclic hydrocarbon group or aromatic hydrocarbon group-chain hydrocarbon group-, *-alicyclic hydrocarbon group or aromatic hydrocarbon group-chain hydrocarbon group-alicyclic hydrocarbon group or aromatic hydrocarbon group-, *-chain hydrocarbon group-group formed by the condensation of an alicyclic hydrocarbon group and an aromatic hydrocarbon group-, *-group formed by the condensation of an alicyclic hydrocarbon group and an aromatic hydrocarbon group-chain hydrocarbon group-, *-chain hydrocarbon group-group formed by the condensation of an alicyclic hydrocarbon group and an aromatic hydrocarbon group-chain hydrocarbon group-, etc. * represents the bonding site with X ¹ .

Examples of substituents that each group may have include the same groups as those listed as substituents that ^L1 may have.
Examples of the cyclic hydrocarbon group ^L2 include alicyclic hydrocarbon groups, aromatic hydrocarbon groups, or groups obtained by condensing these, similar to the groups exemplified in ^L1 .
Examples of chain-like hydrocarbon groups for ^L2 and ^L3 include those similar to those exemplified in ^L1 .
^L2 is preferably a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents (the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-), a cyclic hydrocarbon group having 3 to 20 carbon atoms which may have substituents (the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- ), or a group combining a cyclic hydrocarbon group having 3 to 20 carbon atoms which may have substituents and a chain hydrocarbon group having 1 to 6 carbon atoms which may have substituents (the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-), and a chain hydrocarbon group having 1 to 6 carbon atoms which may have substituents (the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-) A cyclic hydrocarbon group having 3 to 18 carbon atoms that may have substituents (the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- ) or a group formed by combining a cyclic hydrocarbon group having 3 to 18 carbon atoms that may have substituents and a chain hydrocarbon group having 1 to 4 carbon atoms that may have substituents (the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-) is more preferred.
^L3 is preferably a chain hydrocarbon group having 1 to 6 carbon atoms, which may have a single bond or substituents; more preferably a chain hydrocarbon group having 1 to 4 carbon atoms, even more preferably a single bond, a methylene group, or an ethylene group; and even more preferably a single bond or a methylene group.

The alicyclic hydrocarbon group in ring W1 may be monocyclic or polycyclic (including spiro rings, fused rings, or bridged rings), and may be saturated or unsaturated.
Examples of alicyclic hydrocarbon groups include the following. The bonding site can be at any position.
Examples include trivalent or higher alicyclic hydrocarbon groups such as cycloalkanetriyl groups.
Specifically, monocyclic alicyclic hydrocarbon groups include cyclopropanetriyl, cyclobutanetriyl, cyclopentanetriyl, cyclohexanetriyl, cycloheptanetriyl, cyclooctanetriyl, and cyclodecanetriyl. Polycyclic alicyclic hydrocarbon groups include decahydronaphthalentriyl, adamantanetriyl, norbornanetriyl, and bicyclo[3.3.0]octanetriyl.
Other examples include groups in which one or more hydrogen atoms of the aforementioned group are replaced by bonding sites.

The following are examples of groups in which the _-CH₂- contained in an alicyclic hydrocarbon group is replaced with -O-, -S-, -CO-, or _-SO₂- . The -O- or -CO- in the groups shown below may be replaced with -S- or _-SO₂- . The bonding site can be at any position.
The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 24, more preferably 3 to 20, even more preferably 3 to 18, even more preferably 3 to 16, and even more preferably 3 to 12.
The substituents that ring W1 may have are the same groups as those listed as substituents that ^L1 may have.
Ring W1 is preferably an alicyclic hydrocarbon group having 3 to 20 carbon atoms (the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- ), more preferably an alicyclic hydrocarbon group having 3 to 18 carbon atoms (the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- ), even more preferably a group derived from a ring represented by any of formulas (w1-1) to (w1-21), even more preferably a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), or a group derived from a ring represented by formula (w1-15), and even more preferably a group derived from a ring represented by formula (w1-1) or a group derived from a ring represented by formula (w1-2).
[In formulas (w1-1) to (w1-21),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position.
Here, a ring-derived group means a group that has a bonding site at any position in the ring, and in which the _-CH2- contained in the ring may be replaced by -O-, -S-, -CO-, or _-SO2- .

X ^a and X ^b are preferably the same atom, and more preferably both are oxygen atoms.
It is preferable that the carbon atom to which X ^a and ring W are bonded is different from the carbon atom to which X ^b and ring W are bonded.

Ring W represents a cyclic hydrocarbon group having 3 to 36 carbon atoms. The cyclic hydrocarbon group in ring W may be saturated or unsaturated, and may be monocyclic or polycyclic. Examples of cyclic hydrocarbon groups include alicyclic hydrocarbon groups (where the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- ) or aromatic hydrocarbon groups.
Examples of alicyclic hydrocarbon groups include the following. The bonding site can be at any position.
Examples include trivalent or higher alicyclic hydrocarbon groups such as cycloalkanetriyl groups.
Specifically, monocyclic alicyclic hydrocarbon groups include cyclopropanetriyl, cyclobutanetriyl, cyclopentanetriyl, cyclohexanetriyl, cycloheptanetriyl, cyclooctanetriyl, and cyclodecanetriyl. Polycyclic alicyclic hydrocarbon groups include decahydronaphthalentriyl, adamantanetriyl, norbornanetriyl, and bicyclo[3.3.0]octanetriyl.
Other examples include groups in which one or more hydrogen atoms of the aforementioned group are replaced by bonding sites.

Furthermore, the following groups are examples of groups in which the _-CH2- contained in an alicyclic hydrocarbon group is replaced with -O-, -S-, -CO-, or _-SO2- . The -O- or -CO- in the groups shown below may be replaced with -S- or _-SO2- . The bonding site can be at any position.
The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 24, more preferably 3 to 20, even more preferably 3 to 18, even more preferably 3 to 16, and even more preferably 3 to 12.
Examples of aromatic hydrocarbon groups include trivalent or higher aromatic hydrocarbon groups such as arenetriyl groups.
Specifically, examples of aromatic hydrocarbon groups include benzenetriyl groups, naphthalentriyl groups, anthracenatelyyl groups, biphenylentriyl groups, and phenanthrentriyl groups.
Other examples include groups in which one or more hydrogen atoms of the aforementioned group are replaced by bonding sites.
The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 to 24, more preferably 6 to 18, even more preferably 6 to 14, and even more preferably 6 to 10.

The substituents that ring W may have are the same groups as those listed as substituents that ^L1 may have.
Ring W is preferably a cyclic hydrocarbon group having 3 to 24 carbon atoms (the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- ), and preferably a cyclic hydrocarbon group having 3 to 18 carbon atoms (the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or -SO2- _). It may be replaced by -. ) is more preferred, and a group derived from a ring represented by any of formulas (w1-1) to (w1-25) is more preferred, and a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), a group derived from a ring represented by formula (w1-12), a group derived from a ring represented by formula (w1-22), a group derived from a ring represented by formula (w1-23), or a group derived from a ring represented by formula (w1-24) is even more preferred, and a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-6), a group derived from a ring represented by formula (w1-12), a group derived from a ring represented by formula (w1-22), a group derived from a ring represented by formula (w1-23), or a group derived from a ring represented by formula (w1-24) is even more preferred.
[In formulas (w1-1) to (w1-25),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position.
Here, a ring-derived group means a group that has a bonding site at any position in the ring, and in which the _-CH2- contained in the ring may be replaced by -O-, -S-, -CO-, or _-SO2- .

Examples of halogen atoms for ^R1 and ^R2 include fluorine, chlorine, bromine, and iodine.
In ^R1 and ^R2 , the C1-C12 haloalkyl group refers to an alkyl group having a halogen atom and having C1-C12 atoms, and examples include C1-C12 alkyl fluorides, C1-C12 alkyl chlorides, C1-C12 alkyl bromides, and C1-C12 alkyl iodides. Examples of haloalkyl groups include C1-C12 perfluoroalkyl groups (trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, etc.), 2,2,2-trifluoroethyl group, 3,3,3-trifluoropropyl group, 4,4,4-trifluorobutyl group, and 3,3,4,4,4-pentafluorobutyl group, chloromethyl group, bromomethyl group, and iodomethyl group. The number of carbon atoms in the haloalkyl group is preferably 1-9, more preferably 1-6, even more preferably 1-4, and even more preferably 1-3.
Examples of C1 to C12 alkyl groups for ^R1 and ^R2 include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, and nonyl groups. The number of carbon atoms in the alkyl group is preferably 1 to 9, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.

If the _-CH2- contained in the haloalkyl group or alkyl group represented by ^R1 and ^R2 is replaced with -O- or -CO-, the number of carbon atoms before the replacement shall be the total number of carbon atoms in the haloalkyl group or alkyl group. The replaced groups include: hydroxyl group (a group in which the _-CH2- contained in a methyl group is replaced with -O-), carboxyl group (a group in which the _-CH2 - _CH2- contained in an ethyl group is replaced with -O-CO-), alkoxy group (a group in which any position of _-CH2- contained in an alkyl group is replaced with -O-), alkoxycarbonyl group (a group in which any position of _-CH2 - _CH2- contained in an alkyl group is replaced with -O-CO-), alkylcarbonyl group (a group in which any position of _-CH2- contained in an alkyl group is replaced with -CO-), alkylcarbonyloxy group (a group in which any position of -CH2 _{- CH2-} contained in an alkyl group is replaced with -CO-O-), haloalkoxy group (a group in which any position of _-CH2- contained in a haloalkyl group is replaced with -O-), haloalkoxycarbonyl group (a group in which any position of -CH2- contained in a haloalkyl group is replaced with -O-) Examples include groups in which ₂ - _CH2- is replaced by -O-CO-, haloalkylcarbonyl groups (groups in which _-CH2- at any position within a haloalkyl group is replaced by -CO-), haloalkylcarbonyloxy groups (groups in which _-CH2 - _CH2- at any position within a haloalkyl group is replaced by -CO-O-), and groups that combine two or more of these groups.
Examples of alkoxy groups include alkoxy groups having 1 to 11 carbon atoms, such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, and undecyloxy groups. The number of carbon atoms in the alkoxy group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 3.
Alkoxycarbonyl groups, alkylcarbonyl groups, and alkylcarbonyloxy groups represent groups in which a carbonyl group or carbonyloxy group is bonded to an alkyl group or alkoxy group as described above.
Examples of alkoxycarbonyl groups include alkoxycarbonyl groups having 2 to 11 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, and butoxycarbonyl groups. Examples of alkylcarbonyl groups include alkylcarbonyl groups having 2 to 12 carbon atoms, such as acetyl, propionyl, and butyryl groups. Examples of alkylcarbonyloxy groups include alkylcarbonyloxy groups having 2 to 11 carbon atoms, such as acetyloxy, propionyloxy, and butyryloxy groups. The number of carbon atoms in the alkoxycarbonyl group is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 or 3. The number of carbon atoms in the alkylcarbonyl group is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 or 3. The number of carbon atoms in the alkylcarbonyloxy group is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 or 3.
Examples of haloalkoxy groups, haloalkoxycarbonyl groups, haloalkylcarbonyl groups, and haloalkylcarbonyloxy groups include haloalkoxy groups having 1 to 11 carbon atoms, haloalkoxycarbonyl groups having 2 to 11 carbon atoms, haloalkylcarbonyl groups having 2 to 12 carbon atoms, and haloalkylcarbonyloxy groups having 2 to 11 carbon atoms. For example, groups obtained by replacing one or more hydrogen atoms of the above-mentioned groups with halogen atoms are also included.
m1 is preferably an integer from 0 to 5, more preferably an integer from 0 to 4, even more preferably an integer from 0 to 3, even more preferably 0, 1, or 2, and even more preferably 0.
m2 is preferably an integer from 0 to 5, more preferably an integer from 0 to 4, even more preferably 0, 1, 2, or 4, and even more preferably 0 or 1.
^R1 and ^R2 are preferably a halogen atom, a hydroxyl group, a C1-C6 haloalkyl group, or a C1-C6 alkyl group (the _-CH2- contained in the haloalkyl group and the alkyl group may be replaced with -O- or -CO-), more preferably a hydroxyl group, a C1-C4 alkyl group, a C1-C4 haloalkyl group, or a C1-C3 alkoxy group, even more preferably a hydroxyl group or a C1-C3 alkoxy group, and even more preferably a hydroxyl group.

Examples of alkanediyl groups in ^L10 contained in ^R3 include linear alkanediyl groups such as methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group; and branched alkanediyl groups such as ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.
^L10 is preferably an alkanediyl group having 1 to 4 carbon atoms, more preferably an alkanediyl group having 1 to 3 carbon atoms, and even more preferably a methylene group.

Examples of hydrocarbon groups in ^R10 contained in ^R3 include chain hydrocarbon groups such as alkyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining these. Furthermore, examples of cyclic hydrocarbon groups in ^R10 contained in ^R3 include alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining these.
Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group.
The number of carbon atoms in the chain-like hydrocarbon group is preferably 1 to 18, more preferably 1 to 12, even more preferably 1 to 9, even more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
The alicyclic hydrocarbon group may be monocyclic or polycyclic, and examples include the groups shown below. The bonding site can be at any position.
Specifically, monocyclic alicyclic hydrocarbon groups include monocyclic cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl. Polycyclic alicyclic hydrocarbon groups include polycyclic cycloalkyl groups such as decahydronaphthyl, adamantyl, and norbornyl. The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 24, more preferably 3 to 20, even more preferably 3 to 18, even more preferably 3 to 16, and even more preferably 3 to 12.
Examples of aromatic hydrocarbon groups include phenyl groups, naphthyl groups, biphenyl groups, anthryl groups, phenanthryl groups, and binaphthyl groups. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 to 24, more preferably 6 to 18, even more preferably 6 to 14, and even more preferably 6 to 10.

Groups formed by combining these groups include groups formed by combining an aromatic hydrocarbon group with a chain hydrocarbon group (e.g., aromatic hydrocarbon group-chain hydrocarbon group-*, chain hydrocarbon group-aromatic hydrocarbon group-*), groups formed by combining an alicyclic hydrocarbon group with a chain hydrocarbon group (e.g., alicyclic hydrocarbon group-chain hydrocarbon group-*, chain hydrocarbon group-alicyclic hydrocarbon group-*), and groups formed by combining an aromatic hydrocarbon group with an alicyclic hydrocarbon group (e.g., aromatic hydrocarbon group-alicyclic hydrocarbon group-*, alicyclic hydrocarbon group-aromatic hydrocarbon group-*). * indicates the bonding site.
Examples of aromatic hydrocarbon groups—chain hydrocarbon groups—* include aralkyl groups such as benzyl and phenethyl groups.
Examples of chain-type hydrocarbon groups—aromatic hydrocarbon groups—* include tolyl groups, xylyl groups, and cumenyl groups.
Examples of alicyclic hydrocarbon group-chain hydrocarbon group-* include cycloalkylalkyl groups such as cyclohexylmethyl group, cyclohexylethyl group, 1-(adamantan-1-yl)methyl group, and 1-(adamantan-1-yl)-1-methylethyl group.
Examples of chain-type hydrocarbon groups - alicyclic hydrocarbon groups - * include methylcyclohexyl group, dimethylcyclohexyl group, cycloalkyl groups having alkyl groups such as 2-alkyladamantan-2-yl group, etc.
Examples of aromatic hydrocarbon groups—alicyclic hydrocarbon groups—* include phenylcyclohexyl groups.
Examples of alicyclic hydrocarbon groups—aromatic hydrocarbon groups—* include cyclohexylphenyl groups.
In addition, in the combinations, two or more types of alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and chain hydrocarbon groups may be combined.

Groups in which the _-CH2- contained in the hydrocarbon group is replaced with -O-, -S-, -CO-, or _-SO2- include the same groups as those exemplified in ^L1 .
Substituents that the hydrocarbon group or cyclic hydrocarbon group of R ¹⁰ may have include halogen atoms, cyano groups, C1 to C12 alkyl groups (the _-CH2- contained in the alkyl group may be replaced with -O- or -CO-), or groups that combine these.
Examples of halogen atoms include the same groups as those described above.
Examples of alkyl groups having 1 to 12 carbon atoms include the same groups as those described above.
If the _-CH2- group in an alkyl group is replaced with -O- or -CO- as a substituent, the number of carbon atoms before the replacement shall be the total number of carbon atoms in the alkyl group. Examples of the replaced group include hydroxyl group, carboxyl group, alkoxy group, alkoxycarbonyl group, alkylcarbonyl group, alkylcarbonyloxy group, etc.
Examples of alkoxy groups, alkoxycarbonyl groups, alkylcarbonyl groups, and alkylcarbonyloxy groups include alkoxy groups having 1 to 11 carbon atoms, alkoxycarbonyl groups having 2 to 11 carbon atoms, alkylcarbonyl groups having 2 to 12 carbon atoms, and alkylcarbonyloxy groups having 2 to 11 carbon atoms, and are the same groups as those described above.
Examples of combined groups include C1-C12 halogenated alkyl groups. A halogenated alkyl group refers to an alkyl group having a halogen atom, and examples include C1-C12 fluorinated alkyl groups, C1-C12 chlorinated alkyl groups, C1-C12 brominated alkyl groups, C1-C12 iodate alkyl groups, etc., and other groups similar to those described above or described later.
The hydrocarbon group may have one substituent or more substituents.
The substituent is preferably a halogen atom, a C1-C12 alkyl group (the _-CH2- contained in the alkyl group may be replaced with -O- or -CO-), or a group combining these, more preferably an iodine atom, a fluorine atom, a hydroxyl group, a carboxyl group, a C1-C12 alkyl group, a C1-C11 alkoxy group, a C1-C12 fluorinated alkyl group, or a C1-C12 iodized alkyl group, and even more preferably an iodine atom, a fluorine atom, a hydroxyl group, a carboxyl group, a C1-C6 alkyl group, a C1-C5 alkoxy group, a C1-C6 fluorinated alkyl group, or a C1-C6 iodized alkyl group.

In R ¹⁰ , fluorinated alkyl groups and iodized alkyl groups refer to alkyl groups having a fluorine atom and alkyl groups having an iodine atom. Examples of fluorinated alkyl groups and iodized alkyl groups include perfluoroalkyl groups having 1 to 12 carbon atoms (trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, etc.), 2,2,2-trifluoroethyl group, 3,3,3-trifluoropropyl group, 4,4,4-trifluorobutyl group, and 3,3,4,4,4-pentafluorobutyl group, iodomethyl group, etc. The number of carbon atoms in the fluorinated alkyl groups and iodized alkyl groups is preferably 1 to 9, more preferably 1 to 6, even more preferably 1 to 4, and even more preferably 1 to 3.
The hydrocarbon group or cyclic hydrocarbon group of R ¹⁰ may have at least one iodine atom, a fluorine atom, a fluorinated alkyl group having 1 to 12 carbon atoms, or an iodized alkyl group having 1 to 12 carbon atoms, and may have two or more.

R ¹⁰ is preferably a C1-C24 hydrocarbon group having an iodine atom or an iodized alkyl group having C1-C6, an alicyclic hydrocarbon group having C3-C24 having a fluorine atom or a fluorinated alkyl group having C1-C6, or an aromatic hydrocarbon group having C6-C24 having a fluorine atom or a fluorinated alkyl group having C1-C6. A group combining a 3-18 alicyclic hydrocarbon group and a chain hydrocarbon group having 1-12 carbon atoms, a group combining a 6-18 aromatic hydrocarbon group having an iodine atom or an iodized alkyl group having 1-6 carbon atoms and a chain hydrocarbon group having 1-12 carbon atoms, a 3-18 alicyclic hydrocarbon group having a fluorine atom, an iodine atom, a fluorinated alkyl group having 1-6 carbon atoms, or an iodized alkyl group having 1-6 carbon atoms, or a group having a fluorine atom, an iodine atom, a fluorinated alkyl group having 1-6 carbon atoms It is more preferably an aromatic hydrocarbon group having 6 to 18 carbon atoms and an iodized alkyl group having 1 to 6 carbon atoms; it is even more preferably a chain hydrocarbon group having 1 to 6 carbon atoms and an iodine atom; a group combining an alicyclic hydrocarbon group having 3 to 12 carbon atoms and an iodine atom with a chain hydrocarbon group having 1 to 6 carbon atoms; a group combining an aromatic hydrocarbon group having 6 to 14 carbon atoms and an iodine atom with a chain hydrocarbon group having 1 to 6 carbon atoms; an alicyclic hydrocarbon group having 3 to 12 carbon atoms and a fluorine atom, an iodine atom, or a trifluoromethyl group; and it is even more preferably an aromatic hydrocarbon group having 6 to 14 carbon atoms and an iodine atom and an aromatic hydrocarbon group having 1 to 6 carbon atoms and an iodine atom with a chain hydrocarbon group having 1 to 6 carbon atoms; or it is even more preferably an aromatic hydrocarbon group having 6 to 14 carbon atoms and a fluorine atom, an iodine atom, or a trifluoromethyl group. Here, the hydrocarbon group, chain hydrocarbon group, alicyclic hydrocarbon group, and aromatic hydrocarbon group may have substituents other than those mentioned above, and the _-CH2- contained in the hydrocarbon group, chain hydrocarbon group, and alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
^R3 is preferably *-O-CO-R ¹⁰ , *-O-CO-O-R ¹⁰ , or *-O-L ¹ -CO-O-R ¹⁰ .

Examples of anion (I) include the following anions. Among these, the anions represented by formulas (Ia-1) to (Ia-6), (Ia-10) to (Ia-19), (Ia-26) to (Ia-51), and (Ia-55) to (Ia-62) are preferred.

Examples of Z ⁺ organic cations include organic onium cations, organic sulfonium cations, organic iodonium cations, organic ammonium cations, benzothiazolium cations, and organic phosphonium cations. Among these, organic sulfonium cations and organic iodonium cations are preferred, and aryl sulfonium cations are more preferred. Specifically, examples include cations represented by any of formulas (b2-1) to (b2-4) (hereinafter, depending on the formula number, they may be referred to as "cation (b2-1)," etc.).
In equations (b2-1) to (b2-4),
R ^b4 to R ^b6 each independently represent a chain hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 36 carbon atoms, or an aromatic hydrocarbon group having 6 to 36 carbon atoms. The hydrogen atoms in the chain hydrocarbon group may be substituted with a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms. The hydrogen atoms in the alicyclic hydrocarbon group may be substituted with a halogen atom, an aliphatic hydrocarbon group having 1 to 18 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, or a glycidyloxy group. The hydrogen atoms in the aromatic hydrocarbon group may be substituted with a halogen atom, a hydroxyl group, an aliphatic hydrocarbon group having 1 to 18 carbon atoms, an alkyl fluoride group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
R ^b4 and R ^b5 may bond to each other and form a ring together with the sulfur atom to which they are bonded, and the _-CH2- contained in the ring may be replaced with -O-, -S-, or -CO-.
R ^b7 and R ^b8 each independently represent a halogen atom, a hydroxyl group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a fluorinated alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
m² and n² each independently represent an integer between 0 and 5.
When m2 is 2 or greater, multiple R ^b7s may be the same or different, and when n2 is 2 or greater, multiple R ^b8s may be the same or different.
R ^b9 and R ^b10 each independently represent a chain-type hydrocarbon group having 1 to 36 carbon atoms or an alicyclic hydrocarbon group having 3 to 36 carbon atoms.
R ^b9 and R ^b10 may bond to each other and form a ring together with the sulfur atom to which they are bonded, and the _-CH2- contained in the ring may be replaced with -O-, -S-, or -CO-.
R ^b11 represents a hydrogen atom, a chain hydrocarbon group having 1 to 36 carbon atoms, an alicyclic hydrocarbon group having 3 to 36 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms.
R ^b12 represents a chain hydrocarbon group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 18 carbon atoms. The hydrogen atoms in the chain hydrocarbon group may be substituted with an aromatic hydrocarbon group having 6 to 18 carbon atoms, and the hydrogen atoms in the aromatic hydrocarbon group may be substituted with an alkoxy group having 1 to 12 carbon atoms or an alkylcarbonyloxy group having 1 to 12 carbon atoms.
R ^b11 and R ^b12 may bond to each other and form a ring including the -CH-CO- to which they are bonded, and the _-CH2- contained in the ring may be replaced with -O-, -S-, or -CO-.
R ^b13 to R ^b18 each independently represent a halogen atom, a hydroxyl group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a fluorinated alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
R ^b13 and R ^b14 may bond to each other and, together with the benzene ring to which they are bonded, form a ring containing a sulfur atom, and the _-CH2- contained in the ring may be replaced with -O-, -S-, or -CO-.
L ^b31 represents a sulfur atom or an oxygen atom.
o2, p2, s2, and t2 each independently represent an integer between 0 and 5.
q2 and r2 each independently represent an integer between 0 and 4.
u2 represents either 0 or 1.
When o2 is 2 or more, multiple R ^b13 are the same or different; when p2 is 2 or more, multiple R ^b14 are the same or different; when q2 is 2 or more, multiple R ^b15 are the same or different; when r2 is 2 or more, multiple R ^b16 are the same or different; when s2 is 2 or more, multiple R ^b17 are the same or different; when t2 is 2 or more, multiple R ^b18 are the same or different.
When u2 is 0, it is preferable that one of o2, p2, q2, and r2 is 1 or more, and at least one of R ^b13 to R ^b16 is a halogen atom. When u2 is 1, it is preferable that one of o2, p2, s2, t2, q2, and r2 is 1 or more, and at least one of R ^b13 to R ^b18 is a halogen atom.
Furthermore, when u2 is 0, r2 is preferably 1 or greater, and more preferably 1. Also, when u2 is 0 and r2 is 1 or greater, R ^b16 is preferably a halogen atom.

Aliphatic hydrocarbon groups refer to both chain-type hydrocarbon groups and alicyclic hydrocarbon groups.
Examples of chain-type hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, and 2-ethylhexyl.
In particular, the chain-like hydrocarbon groups R ^b9 to R ^b12 preferably have 1 to 12 carbon atoms.
The alicyclic hydrocarbon group may be monocyclic or polycyclic. Examples of monocyclic alicyclic hydrocarbon groups include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl. Examples of polycyclic alicyclic hydrocarbon groups include decahydronaphthyl, adamantyl, norbornyl, and the groups listed below.
In particular, the alicyclic hydrocarbon groups R ^b9 to R ^b12 preferably have 3 to 18 carbon atoms, and more preferably 4 to 12 carbon atoms.

Examples of alicyclic hydrocarbon groups in which a hydrogen atom is substituted with an aliphatic hydrocarbon group include methylcyclohexyl group, dimethylcyclohexyl group, 2-methyladamantan-2-yl group, 2-ethyladamantan-2-yl group, 2-isopropyladamantan-2-yl group, methylnorbornyl group, and isobornyl group. In alicyclic hydrocarbon groups in which a hydrogen atom is substituted with an aliphatic hydrocarbon group, the total number of carbon atoms in the alicyclic hydrocarbon group and the aliphatic hydrocarbon group is preferably 20 or less.

A fluorinated alkyl group refers to an alkyl group having 1 to 12 carbon atoms and containing a fluorine atom, such as a fluoromethyl group, difluoromethyl group, trifluoromethyl group, or perfluorobutyl group. The number of carbon atoms in the fluorinated alkyl group is preferably 1 to 9, more preferably 1 to 6, and even more preferably 1 to 4.

Examples of aromatic hydrocarbon groups include aryl groups such as phenyl, biphenyl, naphthyl, and phenanthryl groups. Aromatic hydrocarbon groups may have a chain-type hydrocarbon group or an alicyclic hydrocarbon group, and examples include aromatic hydrocarbon groups having a chain-type hydrocarbon group (tolyl, xylyl, cumenyl, mesityl, p-ethylphenyl, p-tert-butylphenyl, 2,6-diethylphenyl, 2-methyl-6-ethylphenyl, etc.) and aromatic hydrocarbon groups having an alicyclic hydrocarbon group (p-cyclohexylphenyl, p-adamantylphenyl, etc.).
Furthermore, if the aromatic hydrocarbon group has a chain-type hydrocarbon group or an alicyclic hydrocarbon group, a chain-type hydrocarbon group having 1 to 18 carbon atoms and an alicyclic hydrocarbon group having 3 to 18 carbon atoms are preferred.
Examples of aromatic hydrocarbon groups in which a hydrogen atom is substituted with an alkoxy group include the p-methoxyphenyl group.
Examples of chain-like hydrocarbon groups in which a hydrogen atom is substituted with an aromatic hydrocarbon group include aralkyl groups such as benzyl, phenethyl, phenylpropyl, trityl, naphthylmethyl, and naphthylethyl groups.

Examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy, and dodecyloxy groups.
Examples of alkylcarbonyl groups include acetyl, propionyl, and butyryl groups.
Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.
Examples of alkylcarbonyloxy groups include methylcarbonyloxy group, ethylcarbonyloxy group, propylcarbonyloxy group, isopropylcarbonyloxy group, butylcarbonyloxy group, sec-butylcarbonyloxy group, tert-butylcarbonyloxy group, pentylcarbonyloxy group, hexylcarbonyloxy group, octylcarbonyloxy group, and 2-ethylhexylcarbonyloxy group.

The ring formed by R ^b4 and R ^b5 bonding to each other and together with the sulfur atom to which they are bonded may be monocyclic, polycyclic, aromatic, non-aromatic, saturated, or unsaturated. This ring may have 3 to 18 carbon atoms, preferably 4 to 18 carbon atoms. The ring containing the sulfur atom may have 3 to 12 membered rings, preferably 3 to 7 membered rings, and examples of such rings are shown below. * indicates a bonding site.
The ring formed by R ^b9 and R ^b10 together may be monocyclic, polycyclic, aromatic, non-aromatic, saturated, or unsaturated. This ring may be a 3-membered to 12-membered ring, preferably a 3-membered to 7-membered ring. Examples include a thioran-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathian-4-ium ring.
The ring formed by R ^b11 and R ^b12 together may be monocyclic, polycyclic, aromatic, non-aromatic, saturated, or unsaturated. This ring may be a 3-membered to 12-membered ring, preferably a 3-membered to 7-membered ring. Examples include oxocycloheptane rings, oxocyclohexane rings, oxonorbornane rings, and oxoadamantane rings.

Among cations (b2-1) to (b2-4), cation (b2-1) is preferred.
The following cations can be considered as cations (b2-1):

The following cations can be considered as cations (b2-2):

Examples of cations (b2-3) include the following:

Examples of cations (b2-4) include the following:

Salt (I) is a combination of the anion and the organic cation described above, and these can be combined arbitrarily. Preferably, salt (I) is a combination of an anion represented by any of the formulas (Ia-1) to (Ia-6), (Ia-10) to (Ia-19), (Ia-26) to (Ia-51), or (Ia-55) to (Ia-62) and a cation (b2-1), cation (b2-2), cation (b2-3), or cation (b2-4).

Examples of salt (I) are the salts listed in Table 1. In the table below, each symbol represents the symbol attached to the structure representing the anion or cation described above. For example, salt (I-1) means a salt consisting of the anion represented by formula (Ia-1) and the cation represented by formula (b2-c-1), and represents the salts shown below.


























In particular, salt (I) is as follows: salt (I-1) to salt (I-6), salt (I-10) to salt (I-19), salt (I-26) to salt (I-51), salt (I-55) to salt (I-60), salt (I-64) to salt (I-73), salt (I-80) to salt (I-105), salt (I-109) to salt (I-114), salt (I-118) to salt (I-127), salt (I-134) to salt (I-159), salt (I-163) to salt (I-168), salt (I-172) to salt (I-181), salt (I-188) to salt (I-213), salt (I-217) ) ~ Salt (I-222), Salt (I-226) ~ Salt (I-235), Salt (I-242) ~ Salt (I-267), Salt (I-271) ~ Salt (I-276), Salt (I-280) ~ Salt (I-289), Salt (I-296) ~ Salt (I-321), Salt (I-325) ~ Salt (I-330), Salt (I-334) ~ Salt (I-343), Salt (I-350) ~ Salt (I-375), Salt (I-379) ~ Salt (I-384), Salt (I-388) ~ Salt (I-397), Salt (I-404) ~ Salt (I-429), Salt (I-433) ~ Salt (I -438), Salt (I-442) to Salt (I-451), Salt (I-458) to Salt (I-483), Salt (I-487) to Salt (I-492), Salt (I-496) to Salt (I-505), Salt (I-512) to Salt (I-537), Salt (I-541) to Salt (I-546), Salt (I-550) to Salt (I-559), Salt (I-566) to Salt (I-591), Salt (I-595) to Salt (I-600), Salt (I-604) to Salt (I-613), Salt (I-620) to Salt (I-645), Salt (I-649) to Salt (I-654) Preferably, salts (I-658) to salt (I-667), salt (I-674) to salt (I-699), salt (I-703) to salt (I-708), salt (I-712) to salt (I-721), salt (I-728) to salt (I-753), salt (I-757) to salt (I-762), salt (I-766) to salt (I-775), salt (I-782) to salt (I-807), salt (I-811) to salt (I-816), salt (I-820) to salt (I-829), salt (I-836) to salt (I-861), and salt (I-865) to salt (I-992) are used.

<Method for producing salt (I)>
In salt (I), a salt in which ^R3 is *-O-R10 ^' (a salt represented by formula (I1)) can be produced by reacting a salt represented by formula (I-a) with a compound represented by formula (I-b) in a solvent in the presence of a base catalyst.
[In the formula, all signs have the same meaning as described above. R ¹⁰ ' represents -R ¹⁰ , -CO-R ¹⁰ , -CO-O-R ¹⁰ , -L ¹⁰ -CO-O-R ¹⁰ , and -L ¹⁰ -O-CO-R ^10. ]
Examples of bases include potassium carbonate, potassium iodide, pyridine, triethylamine, and diisopropylethylamine.
Examples of solvents include chloroform, monochlorobenzene, dimethylformamide, acetonitrile, and dimethylformamide.
The reaction temperature is typically between 0°C and 80°C, and the reaction time is typically between 0.5 and 24 hours.

Salts represented by formula (I-a) include, for example, the salts shown below, which are readily available from the market and can also be easily manufactured by known methods.
Compounds represented by formula (I-b) include, for example, the compounds shown below, which are readily available on the market and can also be easily manufactured by known methods.

In salt (I), a salt in which ^R3 is *-O-CO- ^R10 (a salt represented by formula (I2)) can also be produced by reacting the compound represented by formula (I-c) with carbonyldiimidazole in a solvent, and then further reacting it with the salt represented by formula (I-a).
[In the formula, all signs have the same meaning as described above.]
Examples of solvents include chloroform, monochlorobenzene, dimethylformamide, acetonitrile, and dimethylformamide.
The reaction temperature is typically between 0°C and 80°C, and the reaction time is typically between 0.5 and 24 hours.
Compounds represented by formula (I-c) include, for example, the compounds shown below, which are readily available on the market and can also be easily manufactured by known methods.

In salt (I), a salt in which ^R3 is *-O-CO-O- ^R10 (a salt represented by formula (I3)) can also be produced by reacting the compound represented by formula (I-d) with carbonyldiimidazole in a solvent, and then reacting it with the salt represented by formula (I-a).
[In the formula, all signs have the same meaning as described above.]
Examples of solvents include chloroform, monochlorobenzene, dimethylformamide, acetonitrile, and dimethylformamide.
The reaction temperature is typically between 0°C and 80°C, and the reaction time is typically between 0.5 and 24 hours.
Compounds represented by formula (I-d) include, for example, the compounds shown below, which are readily available on the market and can also be easily manufactured by known methods.

[Acid Generator]
The acid generator of the present invention is an acid generator containing salt (I). It may contain one type of salt (I), or it may contain two or more types of salt (I).
The acid generator of the present invention may contain, in addition to salt (I), an acid generator known in the resist field (hereinafter sometimes referred to as "acid generator (B)"). Acid generator (B) may be used alone or in combination of two or more types.

The acid generator (B) may be either nonionic or ionic. Examples of nonionic acid generators include sulfonate esters (e.g., 2-nitrobenzyl ester, aromatic sulfonate, oxime sulfonate, N-sulfonyloxyimide, sulfonyloxyketone, diazonaphthoquinone 4-sulfonate) and sulfones (e.g., disulfone, ketosulfone, sulfonyldiazomethane). Typical ionic acid generators include onium salts containing onium cations (e.g., diazonium salts, phosphonium salts, sulfonium salts, iodonium salts). Examples of onium salt anions include sulfonic acid anions, sulfonylimide anions, and sulfonylmethide anions.

As the acid generator (B), compounds that generate acid by radiation as described in Japanese Patent Publication Nos. 63-26653, 55-164824, 62-69263, 63-146038, 63-163452, 62-153853, 63-146029, U.S. Patent Nos. 3,779,778 and 3,849,137, German Patent No. 3914407, European Patent No. 126,712, etc., can be used. Compounds manufactured by known methods may also be used. Two or more types of acid generators (B) may be used in combination.

The acid generator (B) is preferably a salt represented by formula (B1) (hereinafter sometimes referred to as "acid generator (B1)").
[In formula (B1),
Q ^b1 and Q ^b2 each independently represent a hydrogen atom, a fluorine atom, a perfluoroalkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms.
L ^b1 represents a divalent saturated hydrocarbon group having 1 to 24 carbon atoms, and the _-CH2- contained in the saturated hydrocarbon group may be replaced with -O- or -CO-, and the hydrogen atoms contained in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
Y represents a methyl group which may have substituents or an alicyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, and the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, _-SO2- , or -CO-.
Z1 ⁺ represents an organic cation.

Examples of perfluoroalkyl groups in Q ^b1 and Q ^b2 include trifluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluoroisopropyl group, perfluorobutyl group, perfluorosec-butyl group, perfluorotert-butyl group, perfluoropentyl group, and perfluorohexyl group.
Examples of alkyl groups for Q ^b1 and Q ^b2 include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and hexyl groups.
The acid generator (B) is preferably a fluorine-containing acid generator, and Q ^b1 and Q ^b2 preferably contain at least one fluorine atom or a perfluoroalkyl group, more preferably at least one is a fluorine atom or a perfluoroalkyl group, more preferably each is independently a fluorine atom or a trifluoromethyl group, and even more preferably both are fluorine atoms.

Examples of divalent saturated hydrocarbon groups in L ^b1 include linear alkanediyl groups, branched alkanediyl groups, and monocyclic or polycyclic divalent alicyclic saturated hydrocarbon groups, and may also be groups formed by combining two or more of these groups.
Specifically, linear alkane diyl groups such as methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, and heptadecane-1,17-diyl group;
Branched alkanediyl groups such as ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group;
Monocyclic, divalent, alicyclic saturated hydrocarbon groups such as cycloalkanediyl groups, cyclobutane-1,3-diyl groups, cyclopentane-1,3-diyl groups, cyclohexane-1,4-diyl groups, and cyclooctane-1,5-diyl groups;
Examples include polycyclic divalent alicyclic saturated hydrocarbon groups such as norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-1,5-diyl group, and adamantane-2,6-diyl group.

Examples of groups in which the _-CH2- contained in the divalent saturated hydrocarbon group represented by L ^b1 is replaced with -O- or -CO- include the group represented by any of the formulas (b1-1) to (b1-3). In the groups represented by formulas (b1-1) to (b1-3) and their specific examples, the groups represented by formulas (b1-4) to (b1-11), * and ** represent bonding sites, and * represents the bonding site with -Y.

[In formula (b1-1),
L ^b2 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms.
L ^b3 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups, and the _-CH2- in the saturated hydrocarbon group may be replaced with -O- or -CO-.
However, the total number of carbon atoms in L ^b2 and L ^b3 is 22 or less.
In formula (b1-2),
L ^b4 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms.
L ^b5 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups, and the _-CH2- in the saturated hydrocarbon group may be replaced with -O- or -CO-.
However, the total number of carbon atoms in L ^b4 and L ^b5 is 22 or less.
In formula (b1-3),
L ^b6 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
L ^b7 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups, and the _-CH2- in the saturated hydrocarbon group may be replaced with -O- or -CO-.
However, the total number of carbon atoms in L ^b6 and L ^b7 is 23 or less.

In the groups represented by formulas (b1-1) to (b1-3), if the _-CH2- contained in the saturated hydrocarbon group is replaced by -O- or -CO-, the number of carbon atoms before the replacement shall be the number of carbon atoms of the saturated hydrocarbon group.
Examples of divalent saturated hydrocarbon groups include those similar to the divalent saturated hydrocarbon group of L ^b1 .

L ^b2 is preferably a single bond, a methylene group, -CH( _CF3 )-, or -C( _CF3 ) _2- .
L ^b3 is preferably a divalent saturated hydrocarbon group having 1 to 4 carbon atoms.
L ^b4 is preferably a divalent saturated hydrocarbon group having 1 to 8 carbon atoms, and the hydrogen atoms in the divalent saturated hydrocarbon group may be substituted with fluorine atoms, and more preferably a methylene group, -CH( _CF3 )-, or -C( _CF3 ) _2- .
L ^b5 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b6 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 4 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms.
L ^b7 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups, and _{the -CH2-} in the divalent saturated hydrocarbon group may be replaced with -O- or -CO-.

As for the group in which the _-CH2- contained in the divalent saturated hydrocarbon group represented by L ^b1 is replaced with -O- or -CO-, the group represented by formula (b1-1) or formula (b1-3) is preferred.
The group represented by formula (b1-1) includes the groups represented by formulas (b1-4) to (b1-8), respectively.
[In formula (b1-4),
L ^b8 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
In formula (b1-5),
L ^b9 represents a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and the _-CH2- contained in the divalent saturated hydrocarbon group may be replaced with -O- or -CO-.
L ^b10 represents a single bond or a divalent saturated hydrocarbon group having 1 to 19 carbon atoms, and the hydrogen atoms in the divalent saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
However, the total number of carbon atoms in L ^b9 and L ^b10 is 20 or less.
In formula (b1-6),
L ^b11 represents a divalent saturated hydrocarbon group with 1 to 21 carbon atoms.
L ^b12 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and the hydrogen atoms in the divalent saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
However, the total number of carbon atoms in L ^b11 and L ^b12 is 21 or less.
In formula (b1-7),
L ^b13 represents a divalent saturated hydrocarbon group with 1 to 19 carbon atoms.
L ^b14 represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and _{the -CH2-} contained in the divalent saturated hydrocarbon group may be replaced by -O- or -CO-.
L ^b15 represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and the hydrogen atoms in the divalent saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
However, the total number of carbon atoms in L ^b13 to L ^b15 is 19 or less.
In formula (b1-8),
L ^b16 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and the _-CH2- contained in the divalent saturated hydrocarbon group may be replaced with -O- or -CO-.
L ^b17 represents a divalent saturated hydrocarbon group with 1 to 18 carbon atoms.
L ^b18 represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, and the hydrogen atoms in the divalent saturated hydrocarbon group may be substituted with fluorine atoms or hydroxyl groups.
However, the total number of carbon atoms in L ^b16 to L ^b18 is 19 or less.
L ^b8 is preferably a divalent saturated hydrocarbon group having 1 to 4 carbon atoms.
L ^b9 is preferably a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b10 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 19 carbon atoms, and more preferably a single bond or a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b11 is preferably a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b12 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b13 is preferably a divalent saturated hydrocarbon group having 1 to 12 carbon atoms.
L ^b14 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 6 carbon atoms.
L ^b15 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and more preferably a single bond or a divalent saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^b16 is preferably a divalent saturated hydrocarbon group having 1 to 12 carbon atoms.
L ^b17 is preferably a divalent saturated hydrocarbon group having 1 to 6 carbon atoms.
L ^b18 is preferably a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, and more preferably a single bond or a divalent saturated hydrocarbon group having 1 to 4 carbon atoms.

The groups represented by formula (b1-3) include those represented by formulas (b1-9) to (b1-11), respectively.
[In formula (b1-9),
L ^b19 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and the hydrogen atoms contained in the saturated hydrocarbon group may be substituted with fluorine atoms.
L ^b20 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with a fluorine atom, a hydroxyl group, or an alkylcarbonyloxy group. The _-CH2- in the alkylcarbonyloxy group may be replaced with -O- or -CO-, and the hydrogen atoms in the alkylcarbonyloxy group may be substituted with a hydroxyl group.
However, the total number of carbon atoms in L ^b19 and L ^b20 must be 23 or less.
In formula (b1-10),
L ^b21 represents a single bond or a divalent saturated hydrocarbon group having 1 to 21 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with fluorine atoms.
L ^b22 represents a single bond or a divalent saturated hydrocarbon group having 1 to 21 carbon atoms.
L ^b23 represents a single bond or a divalent saturated hydrocarbon group having 1 to 21 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with a fluorine atom, a hydroxyl group, or an alkylcarbonyloxy group. The _-CH2- in the alkylcarbonyloxy group may be replaced with -O- or -CO-, and the hydrogen atoms in the alkylcarbonyloxy group may be substituted with a hydroxyl group.
However, the total number of carbon atoms in L ^b21 , L ^b22 , and L ^b23 is 21 or less.
In formula (b1-11),
L ^b24 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and the hydrogen atoms contained in the saturated hydrocarbon group may be substituted with fluorine atoms.
L ^b25 represents a divalent saturated hydrocarbon group with 1 to 21 carbon atoms.
L ^b26 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and the hydrogen atoms in the saturated hydrocarbon group may be substituted with a fluorine atom, a hydroxyl group, or an alkylcarbonyloxy group. The _-CH2- in the alkylcarbonyloxy group may be replaced with -O- or -CO-, and the hydrogen atoms in the alkylcarbonyloxy group may be substituted with a hydroxyl group.
However, the total number of carbon atoms in L ^b24 , L ^b25 , and L ^b26 is 21 or less.

In addition, in the group represented by formula (b1-9) to the group represented by formula (b1-11), if a hydrogen atom in a saturated hydrocarbon group is substituted with an alkylcarbonyloxy group, the number of carbon atoms before the substitution shall be the number of carbon atoms in the saturated hydrocarbon group.
Examples of alkylcarbonyloxy groups include acetyloxy group, propionyloxy group, butyryloxy group, cyclohexylcarbonyloxy group, and adamantylcarbonyloxy group.

The following are examples of bases represented by formula (b1-4):

The following are examples of bases represented by formula (b1-5):

The following are examples of bases represented by formula (b1-6):

The following are examples of bases represented by formula (b1-7):

The following are examples of bases represented by formula (b1-8):

The following are examples of bases represented by formula (b1-2):

The following are examples of bases represented by formula (b1-9):

The following are examples of bases represented by formula (b1-10):

The following are examples of bases represented by formula (b1-11):

Examples of alicyclic hydrocarbon groups represented by Y include those represented by formulas (Y1) to (Y11) and (Y36) to (Y38).
When the _-CH2- contained in the alicyclic hydrocarbon group represented by Y is replaced by -O-, -S-, _-SO2- , or -CO-, the number of replacements may be one or two or more. Examples of such groups include those represented by formulas (Y12) to (Y35) and (Y39) to (Y43). The -O- or -CO- in the groups shown below may also be replaced by -S- or _-SO2- . * indicates a bonding site with L ^b1 .
The alicyclic hydrocarbon group represented by Y is preferably a group represented by any of the formulas (Y1) to (Y20), (Y26), (Y27), (Y30), (Y31), (Y39) to (Y43), more preferably a group represented by formula (Y11), (Y15), (Y16), (Y20), (Y26), (Y27), (Y30), (Y31), (Y39), (Y40), (Y42), or (Y43), and even more preferably a group represented by formula (Y11), (Y15), (Y20), (Y26), (Y27), (Y30), (Y31), (Y39), (Y40), (Y42), or (Y43).
When the alicyclic hydrocarbon group represented by Y is a spiro ring having an oxygen atom, such as formulas (Y28) to (Y35), (Y39), (Y40), (Y42), and (Y43), it is preferable that the alkanediyl group between the two oxygen atoms has one or more fluorine atoms. Furthermore, it is preferable that the methylene group adjacent to the oxygen atom among the alkanediyl groups contained in the ketal structure is not substituted with a fluorine atom.

Substituents for the methyl group represented by Y include halogen atoms, hydroxyl groups, alicyclic hydrocarbon groups having 3 to 16 carbon atoms, aromatic hydrocarbon groups having 6 to 18 carbon atoms, glycidyloxy groups, -( _CH2 ) _ja- CO-O- ^Rb1 groups or -( _CH2 ) _ja -O-CO- ^Rb1 groups (wherein ^Rb1 represents an alkyl group having 1 to 16 carbon atoms, an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group combining these. ja represents an integer from 0 to 4. The _-CH2- contained in the alkyl group and the alicyclic hydrocarbon group may be replaced with -O-, _-SO2- , or -CO-, and the hydrogen atoms contained in the alkyl group, the alicyclic hydrocarbon group, and the aromatic hydrocarbon group may be replaced with hydroxyl groups or fluorine atoms).
Substituents for the alicyclic hydrocarbon group represented by Y include halogen atoms, hydroxyl groups, C1-C16 alkyl groups which may be substituted with hydroxyl groups (the _-CH2- contained in the alkyl group may be replaced with -O- or -CO-), C3-C16 alicyclic hydrocarbon groups, C6-C18 aromatic hydrocarbon groups, C7-C21 aralkyl groups, glycidyloxy groups, -( _CH2 ) _ja- CO-O-R ^b1 group or -( _CH2 ) _ja -O-CO-R ^b1 group (wherein R ^b1 represents an alkyl group with C1-C16, a C3-C16 alicyclic hydrocarbon group, a C6-C18 aromatic hydrocarbon group, or a group combining these. ja represents an integer from 0 to 4. The _-CH2- contained in the alkyl group and the alicyclic hydrocarbon group may be -O- or _-SO2 Examples include: - or -CO-, and the hydrogen atoms contained in the alkyl group, the alicyclic hydrocarbon group, and the aromatic hydrocarbon group may be replaced with hydroxyl groups or fluorine atoms.

Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.
Examples of alicyclic hydrocarbon groups include cyclopentyl group, cyclohexyl group, methylcyclohexyl group, dimethylcyclohexyl group, cycloheptyl group, cyclooctyl group, norbornyl group, and adamantyl group. Alicyclic hydrocarbon groups may also have chain hydrocarbon groups, such as methylcyclohexyl group and dimethylcyclohexyl group. The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 12, and more preferably 3 to 10.
Examples of aromatic hydrocarbon groups include phenyl groups, naphthyl groups, anthryl groups, biphenyl groups, phenanthryl groups, and other aryl groups. Aromatic hydrocarbon groups may have a chain-like hydrocarbon group or an alicyclic hydrocarbon group. Examples of aromatic hydrocarbon groups having a chain-like hydrocarbon group include tolyl groups, xylyl groups, cumenyl groups, mesityl groups, p-ethylphenyl groups, p-tert-butylphenyl groups, 2,6-diethylphenyl groups, and 2-methyl-6-ethylphenyl groups. Examples of aromatic hydrocarbon groups having an alicyclic hydrocarbon group include p-cyclohexylphenyl groups and p-adamantylphenyl groups. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 to 14, and more preferably 6 to 10.
Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl, and dodecyl groups. The number of carbon atoms in the alkyl group is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4.
Examples of alkyl groups substituted with a hydroxyl group include hydroxymethyl groups, hydroxyethyl groups, and other hydroxyalkyl groups.
Examples of aralkyl groups include benzyl groups, phenethyl groups, phenylpropyl groups, naphthylmethyl groups, and naphthylethyl groups.
Groups in which the _-CH2- contained in an alkyl group is replaced with -O-, _-SO2- , or -CO- include alkoxy groups, alkylsulfonyl groups, alkoxycarbonyl groups, alkylcarbonyl groups, alkylcarbonyloxy groups, or groups that combine these.
Examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy, and dodecyloxy groups. The number of carbon atoms in the alkoxy group is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4.
Examples of alkoxycarbonyl groups include methoxycarbonyl groups, ethoxycarbonyl groups, and butoxycarbonyl groups. The number of carbon atoms in the alkoxycarbonyl group is preferably 2 to 12, more preferably 2 to 6, and even more preferably 2 to 4.
Examples of alkylcarbonyl groups include acetyl groups, propionyl groups, and butyryl groups. The number of carbon atoms in the alkylcarbonyl group is preferably 2 to 12, more preferably 2 to 6, and even more preferably 2 to 4.
Examples of alkylsulfonyl groups include methylsulfonyl groups, ethylsulfonyl groups, and propylsulfonyl groups. The number of carbon atoms in the alkylsulfonyl group is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4.
Examples of alkylcarbonyloxy groups include acetyloxy groups, propionyloxy groups, and butyryloxy groups. The number of carbon atoms in the alkylcarbonyloxy group is preferably 2 to 12, more preferably 2 to 6, and even more preferably 2 to 4.
Examples of combined groups include groups combining an alkoxy group and an alkyl group, groups combining two alkoxy groups, groups combining an alkoxy group and an alkylcarbonyl group, and groups combining an alkoxy group and an alkylcarbonyloxy group.
Examples of groups combining an alkoxy group and an alkyl group include alkoxyalkyl groups such as methoxymethyl, methoxyethyl, ethoxyethyl, and ethoxymethyl groups. The number of carbon atoms in the alkoxyalkyl group is preferably 2 to 12, more preferably 2 to 6, and even more preferably 2 to 4.
Examples of groups formed by combining alkoxy groups include alkoxyalkoxy groups such as methoxymethoxy, methoxyethoxy, ethoxymethoxy, and ethoxyethoxy. The number of carbon atoms in the alkoxyalkoxy group is preferably 2 to 12, more preferably 2 to 6, and even more preferably 2 to 4.
Examples of groups combining an alkoxy group and an alkylcarbonyl group include alkoxyalkylcarbonyl groups such as methoxyacetyl group, methoxypropionyl group, ethoxyacetyl group, and ethoxypropionyl group. The number of carbon atoms in the alkoxyalkylcarbonyl group is preferably 3 to 13, more preferably 3 to 7, and even more preferably 3 to 5.
Examples of groups combining an alkoxy group and an alkylcarbonyloxy group include alkoxyalkylcarbonyloxy groups such as methoxyacetyloxy group, methoxypropionyloxy group, ethoxyacetyloxy group, and ethoxypropionyloxy group. The number of carbon atoms in the alkoxyalkylcarbonyloxy group is preferably 3 to 13, more preferably 3 to 7, and even more preferably 3 to 5.
Groups in which the _-CH2- contained in an alicyclic hydrocarbon group is replaced with -O-, _-SO2- , or -CO-, etc., include the groups represented by formulas (Y12) to (Y35) and (Y39) to (Y43).

Y is preferably a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, more preferably a cyclic hydrocarbon group having 3 to 20 carbon atoms which may have substituents, even more preferably a cyclic hydrocarbon group having 3 to 18 carbon atoms which may have substituents, and even more preferably an adamantyl group which may have substituents or a norbornyl group which may have substituents, and the _-CH2- constituting the cyclic hydrocarbon group, adamantyl group and norbornyl group may be replaced with -O-, -S-, _-SO2- or -CO-, specifically the following:

In particular, Y is preferably an adamantyl group, a hydroxyadamantyl group, an oxoadamantyl group, a norbornane lactone group, or a group represented by formulas (Y42), (Y100) to (Y114), (Y134) to (Y139).

The anions in the salt represented by formula (B1) are preferably the anions represented by formulas (B1-A-1) to (B1-A-65) [hereinafter, depending on the formula number, they may be referred to as "anion (B1-A-1)," etc.], and more preferably the anions represented by any of formulas (B1-A-1) to (B1-A-4), formula (B1-A-9), formula (B1-A-10), formula (B1-A-24) to (B1-A-33), formula (B1-A-36) to (B1-A-40), or formula (B1-A-47) to (B1-A-65).

Here, ^Ri2 to ^Ri7 are, independently of each other, for example, C1-C4 alkyl groups, preferably methyl or ethyl groups. ^Ri8 is, for example, a C1-C12 chain hydrocarbon group, preferably a C1-C4 alkyl group, a C5-C12 alicyclic hydrocarbon group, or a group formed by a combination thereof, more preferably a methyl group, ethyl group, cyclohexyl group, or adamantyl group. ^{L A41} is a single bond or a C1-C4 alkanediyl group. ^{Q b1} and Q ^b2 have the same meaning as above.
Specific examples of anions in the salt represented by formula (B1) include the anions described in Japanese Patent Publication No. 2010-204646.

Preferred anions in the salt represented by formula (B1) are the anions represented by formulas (B1a-1) to (B1a-43), respectively.

Among these, anions represented by any of the following formulas are preferred: (B1a-1) to (B1a-3), (B1a-7) to (B1a-16), (B1a-18), (B1a-19), and (B1a-22) to (B1a-41).
Examples of organic cations for Z1 ⁺ include organic onium cations, organic sulfonium cations, organic iodonium cations, organic ammonium cations, benzothiazolium cations, and organic phosphonium cations. Among these, organic sulfonium cations and organic iodonium cations are preferred, and aryl sulfonium cations are more preferred. Examples of aryl sulfonium cations include those similar to the Z ⁺ cation in formula (I).

The acid generator (B) is a combination of the anion and the organic cation described above, and these can be combined arbitrarily. Preferred examples of the acid generator (B) include a combination of an anion represented by any of the formulas (B1a-1) to (B1a-3), (B1a-7) to (B1a-16), (B1a-18), (B1a-19), (B1a-22) to (B1a-41) and a cation (b2-1), cation (b2-2), cation (b2-3), or cation (b2-4).

Preferably, the acid generator (B) is represented by formulas (B1-1) to (B1-60). Among these, those containing arylsulfonium cations are preferred, and those represented by formulas (B1-1) to (B1-3), (B1-5) to (B1-7), (B1-11) to (B1-14), (B1-20) to (B1-26), (B1-29), and (B1-31) to (B1-60) are particularly preferred.

When the acid generator contains both salt (I) and acid generator (B), the ratio of salt (I) to acid generator (B) (mass ratio; salt (I): acid generator (B)) is typically 1:99 to 99:1, preferably 2:98 to 98:2, more preferably 5:95 to 95:5, even more preferably 10:90 to 90:10, and particularly preferably 15:85 to 85:15.

[Resist composition]
The resist composition of the present invention contains an acid generator containing salt (I) and a resin having an acid-unstable group (hereinafter sometimes referred to as "resin (A)"). Here, "acid-unstable group" means a group having a leaving group, in which the leaving group is removed upon contact with an acid, and the constituent unit is converted into a constituent unit having a hydrophilic group (for example, a hydroxyl group or a carboxyl group).
The resist composition of the present invention preferably contains a quencher such as a salt that generates an acid with a lower acidity than the acid generated from the acid generator (hereinafter sometimes referred to as "quencher (C)"), and preferably contains a solvent (hereinafter sometimes referred to as "solvent (E)").

<Acid Generator>
In the resist composition of the present invention, the total content of the acid generator is preferably 1 to 45 parts by mass, more preferably 1 to 40 parts by mass, even more preferably 3 to 40 parts by mass, even more preferably 3 to 35 parts by mass, and even more preferably 5 to 35 parts by mass, based on 100 parts by mass of the resin (A) described below.

<Resin (A)>
Resin (A) contains structural units having acid-unstable groups (hereinafter sometimes referred to as "structural unit (a1)"). Preferably, resin (A) further contains structural units other than structural unit (a1). Examples of structural units other than structural unit (a1) include structural units that do not have acid-unstable groups (hereinafter sometimes referred to as "structural unit (s)"), structural units other than structural unit (a1) and structural unit (s) (for example, structural units having halogen atoms as described later (hereinafter sometimes referred to as "structural unit (a4)"), structural units having non-eliminating hydrocarbon groups as described later (hereinafter sometimes referred to as "structural unit (a5)"), and structural units derived from other monomers known in the art.

<Structural unit (a1)>
The structural unit (a1) is derived from a monomer having an acid-unstable group (hereinafter sometimes referred to as "monomer (a1)").
The acid-unstable group contained in resin (A) is preferably the group represented by formula (1) (hereinafter also referred to as group (1)) and/or the group represented by formula (2) (hereinafter also referred to as group (2)).
[In formula (1), ^Ra1 , ^Ra2 , and ^Ra3 each independently represent an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group having a combination thereof. Alternatively, ^Ra1 and ^Ra2 are bonded to each other to form a non-aromatic hydrocarbon ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded.
ma and na each independently represent either 0 or 1, and at least one of ma and na represents 1.
* indicates a connection site.
[In formula (2), R ^a1' and R ^a2' each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, R ^a3' represents a hydrocarbon group having 1 to 20 carbon atoms, or R ^a2' and R ^a3' are bonded to each other to form a heterocycle having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded and X, and the _-CH2- contained in the hydrocarbon group and the heterocycle may be replaced with -O- or -S-.
X represents either an oxygen atom or a sulfur atom.
'na' represents 0 or 1.
* indicates a connection site.

Examples of alkyl groups in ^Ra1 , ^Ra2 , and ^Ra3 include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl groups.
Examples of alkenyl groups in R ^a1 , R ^a2 , and R ^a3 include ethenyl, propenyl, isopropenyl, butenyl, isobutenyl, tert-butenyl, pentenyl, hexenyl, heptenyl, octenyl, isooctenyl, and nonenyl groups.
The alicyclic hydrocarbon groups in R ^a1 , R ^a2 , and R ^a3 may be monocyclic or polycyclic. Examples of monocyclic alicyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of polycyclic alicyclic hydrocarbon groups include decahydronaphthyl, adamantyl, norbornyl, and the following groups (* indicates a bonding site). The number of carbon atoms in the alicyclic hydrocarbon groups of R ^a1 , R ^a2 , and R ^a3 is preferably 3 to 16.
Aromatic hydrocarbon groups in R ^a1 , R ^a2 , and R ^a3 include aryl groups such as phenyl, naphthyl, anthryl, biphenyl, and phenanthryl groups.
Examples of combined groups include groups that combine alkyl groups and alicyclic hydrocarbon groups as described above (for example, alkylcycloalkyl groups or cycloalkylalkyl groups such as methylcyclohexyl group, dimethylcyclohexyl group, methylnorbornyl group, cyclohexylmethyl group, adamantylmethyl group, adamantyldimethyl group, norbornylethyl group, etc.), aralkyl groups such as benzyl group, aromatic hydrocarbon groups having alkyl groups (p-methylphenyl group, p-tert-butylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups having alicyclic hydrocarbon groups (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), and aryl-cycloalkyl groups such as phenylcyclohexyl group.
Preferably, ma is 0 and na is 1.
When R ^a1 and R ^a2 are bonded to each other to form a non-aromatic hydrocarbon ring, the following rings are examples of -C (R ^a1 ) (R ^a2 ) (R ^a3 ). The non-aromatic hydrocarbon ring preferably has 3 to 12 carbon atoms. * indicates a bond site with -O-.

Examples of hydrocarbon groups in R ^a1' , R ^a2' , and R ^a3' include alkyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining these.
Examples of alkyl groups and alicyclic hydrocarbon groups are the same as those listed in ^Ra1 , ^Ra2 , and ^Ra3 .
Examples of aromatic hydrocarbon groups include aryl groups such as phenyl, naphthyl, anthryl, biphenyl, and phenanthryl groups.
Examples of combined groups include groups that combine alkyl groups and alicyclic hydrocarbon groups as described above (for example, alkylcycloalkyl groups or cycloalkylalkyl groups such as methylcyclohexyl group, dimethylcyclohexyl group, methylnorbornyl group, cyclohexylmethyl group, adamantylmethyl group, adamantyldimethyl group, norbornylethyl group, etc.), aralkyl groups such as benzyl group, aromatic hydrocarbon groups having alkyl groups (p-methylphenyl group, p-tert-butylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups having alicyclic hydrocarbon groups (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), and aryl-cycloalkyl groups such as phenylcyclohexyl group.
When R ^a2' and R ^a3' bond to each other and form a heterocycle with the carbon atom to which they are bonded and X, the following rings can be considered as -C(R ^a1' )(R ^a2' )-X- ^{R a3'} . * indicates a bonding site.
It is preferable that at least one of R ^a1' and R ^a2' is a hydrogen atom.
na' is preferably 0.

The following are examples of base (1):
In formula (1), ^Ra1 , ^Ra2 , and ^Ra3 are alkyl groups, with ma = 0 and na = 1. A tert-butoxycarbonyl group is preferred as the group.
In formula (1), ^Ra1 and ^Ra2 , together with the carbon atoms to which they are bonded, form an adamantyl group, and ^Ra3 is an alkyl group with ma = 0 and na = 1.
In formula (1), ^Ra1 and ^Ra2 are each independently alkyl groups, and ^Ra3 is an adamantyl group with ma = 0 and na = 1.
The following are specific examples of group (1). * indicates a bonding site.
The following are specific examples of group (2). * indicates a bonding site.

The monomer (a1) is preferably a monomer having an acid-unstable group and an ethylenically unsaturated bond, and more preferably a (meth)acrylic monomer having an acid-unstable group.

Among (meth)acrylic monomers having acid-unstable groups, those having alicyclic hydrocarbon groups with 5 to 20 carbon atoms are preferred. Using a resin (A) having structural units derived from a monomer (a1) with a bulky structure such as an alicyclic hydrocarbon group in the resist composition can improve the resolution of the resist pattern.

Structural units derived from (meth)acrylic monomers having group (1) include structural units represented by formula (a1-0) (hereinafter sometimes referred to as structural unit (a1-0)), structural units represented by formula (a1-1) (hereinafter sometimes referred to as structural unit (a1-1)), or structural units represented by formula (a1-2) (hereinafter sometimes referred to as structural unit (a1-2)). Preferably, at least one or two structural units selected from the group consisting of structural unit (a1-0), structural unit (a1-1), and structural unit (a1-2), and more preferably, at least one or two structural units selected from the group consisting of structural unit (a1-1) and structural unit (a1-2). These may be used individually or in combination of two or more.
[In formulas (a1-0), (a1-1), and (a1-2),
L ^a01 , L ^a1 , and L ^a2 each independently represent -O- or *-O-(CH ₂ ) _k1 -CO-O-, where k1 is an integer from 1 to 7, and * represents the bond site with -CO-.
^Ra01 , ^Ra4 , and ^Ra5 each independently represent a hydrogen atom, a halogen atom, or a C1-C6 alkyl group which may contain a halogen atom.
R ^a02 , R ^a03 , and R ^a04 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a combination thereof.
^Ra6 and ^Ra7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group formed by a combination of these.
m1 represents an integer between 0 and 14.
n1 represents an integer between 0 and 10.
n1' represents an integer between 0 and 3.

R ^a01 , R ^a4 , and R ^a5 are preferably hydrogen atoms or methyl groups, and more preferably methyl groups.
L ^a01 , L ^a1 , and L ^a2 are preferably oxygen atoms or *-O-( _CH2 ) _k01 -CO-O- (wherein k01 is preferably an integer from 1 to 4, more preferably 1), and more preferably oxygen atoms.
Examples of alkyl groups, alkenyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and combinations thereof in R ^a02 , R ^a03 , R ^a04 , R ^a6 , and R ^a7 include the same groups as those listed for R ^a1 , R ^a2 , and R ^a3 in group (1).
The alkyl groups in R ^a02 , R ^a03 , and R ^a04 are preferably alkyl groups having 1 to 6 carbon atoms, more preferably methyl or ethyl groups, and even more preferably methyl groups.
The alkyl groups in ^Ra6 and ^Ra7 are preferably alkyl groups having 1 to 6 carbon atoms, more preferably methyl, ethyl, isopropyl, or t-butyl groups, and even more preferably ethyl, isopropyl, or t-butyl groups.
The alkenyl group in R ^a6 and R ^a7 is preferably an alkenyl group having 2 to 6 carbon atoms, and more preferably an ethenyl group, propenyl group, isopropenyl group, or butenyl group.
The number of carbon atoms in the alicyclic hydrocarbon groups of ^{Ra02, Ra03 , Ra04} , ^Ra6 , and ^Ra7 is preferably 5 to 12, and more preferably 5 to 10.
The number of carbon atoms in ^the aromatic hydrocarbon groups of Ra02, ^Ra03 , ^Ra04 , ^Ra6 , and ^Ra7 is preferably 6 to 12, and more preferably 6 to 10.
In groups formed by combining an alkyl group and an alicyclic hydrocarbon group, it is preferable that the total number of carbon atoms in the combined alkyl group and alicyclic hydrocarbon group is 18 or less.
In groups formed by combining an alkyl group and an aromatic hydrocarbon group, it is preferable that the total number of carbon atoms in the combined alkyl group and aromatic hydrocarbon group is 18 or less.
R ^a02 and R ^a03 are preferably C1-C6 alkyl groups or C6-C12 aromatic hydrocarbon groups, and more preferably methyl, ethyl, phenyl, or naphthyl groups.
R ^a04 is preferably an alkyl group having 1 to 6 carbon atoms or an alicyclic hydrocarbon group having 5 to 12 carbon atoms, and more preferably a methyl group, an ethyl group, a cyclohexyl group, or an adamantyl group.
^Ra6 and ^Ra7 are each independently preferably an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms, more preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an ethenyl group, a phenyl group, or a naphthyl group, and even more preferably an ethyl group, an isopropyl group, a t-butyl group, an ethenyl group, or a phenyl group.
m1 is preferably an integer between 0 and 3, and more preferably 0 or 1.
n1 is preferably an integer from 0 to 3, and more preferably 0 or 1.
n1' is preferably 0 or 1.

Examples of structural units (a1-0) include structural units represented by any of the formulas (a1-0-1) to (a1-0-18) and structural units in which the methyl group corresponding to R ^a01 in structural unit (a1-0) is replaced by a hydrogen atom, a halogen atom, a haloalkyl group (an alkyl group having a halogen atom), or another alkyl group. Structural units represented by any of the formulas (a1-0-1) to (a1-0-10), (a1-0-13), or (a1-0-14) are preferred.

Examples of structural units (a1-1) include structural units derived from monomers described in Japanese Patent Publication No. 2010-204646. Among these, structural units represented by any of formulas (a1-1-1) to (a1-1-7) and structural units in which the methyl group corresponding to R ^a4 in structural unit (a1-1) is replaced with a hydrogen atom, a halogen atom, a haloalkyl group, or another alkyl group are preferred, and structural units represented by any of formulas (a1-1-1) to (a1-1-4) are more preferred.

Examples of structural units (a1-2) include structural units represented by any of formulas (a1-2-1) to (a1-2-14) and structural units in which the methyl group corresponding to R ^a5 in structural unit (a1-2) is replaced by a hydrogen atom, a halogen atom, a haloalkyl group, or another alkyl group. Structural units represented by any of formulas (a1-2-2), (a1-2-5), (a1-2-6), and (a1-2-10) to (a1-2-14) are preferred.

When resin (A) contains structural units (a1-0), the content is 5 mol% or more, preferably 10 mol% or more, relative to the total structural units of resin (A). Alternatively, it can be 80 mol% or less, preferably 75 mol% or less, and more preferably 70 mol% or less. Specifically, it can be 5 to 80 mol%, preferably 5 to 75 mol%, and more preferably 10 to 70 mol%.
When resin (A) contains structural unit (a1-1) and/or structural unit (a1-2), the total content of these is 10 mol% or more, preferably 15 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, and even more preferably 30 mol% or more, relative to the total structural units of resin (A). Alternatively, it may be 95 mol% or less, preferably 90 mol% or less, more preferably 85 mol% or less, even more preferably 80 mol% or less, even more preferably 75 mol% or less, and even more preferably 70 mol% or less. Specifically, it may be 10 to 90 mol%, preferably 15 to 85 mol%, more preferably 20 to 80 mol%, even more preferably 20 to 75 mol%, and even more preferably 20 to 70 mol%.

Examples of structural units having a base (2) in structural unit (a1) include the structural unit represented by formula (a1-4) (hereinafter sometimes referred to as "structural unit (a1-4)").
[In formula (a1-4),
R ^a32 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
R ^a33 represents a halogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C12 alkoxyalkyl group, a C2-C12 alkoxyalkoxy group, a C2-C4 alkylcarbonyl group, a C2-C4 alkylcarbonyloxy group, an acryloyloxy group, or a methacryloyloxy group.
A ^a30 represents a single bond or ^* -X ^a31- (A ^a32 -X ^a32 ) _nc- , where * represents the bonding site with the carbon atom to which -R ^a32 is bonded.
A ^a32 represents an alkanediyl group with 1 to 6 carbon atoms.
X ^a31 and X ^a32 independently represent -O-, -CO-O-, or -O-CO-, respectively.
nc represents 0 or 1.
'la' represents an integer between 0 and 4. If 'la' is an integer greater than or equal to 2, multiple R ^a33s may be identical or different from one another.
R ^a34 and R ^a35 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and R ^a36 represents a hydrocarbon group having 1 to 20 carbon atoms, or R ^a35 and R ^a36 are bonded to each other to form a divalent hydrocarbon group having 2 to 20 carbon atoms together with the -C-O- to which they are bonded, and _{the -CH2-} contained in the hydrocarbon group and the divalent hydrocarbon group may be replaced with -O- or -S-.

Examples of halogen atoms in R ^a32 and R ^a33 include fluorine atoms, chlorine atoms, and bromine atoms.
Examples of C1-C6 alkyl groups that may have halogen atoms in R ^a32 include trifluoromethyl, difluoromethyl, methyl, perfluoroethyl, 2,2,2-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl, perfluoropropyl, 2,2,3,3,3-pentafluoropropyl, propyl, perfluorobutyl, 1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl, 2,2,3,3,4,4,5,5,5-nonafluoropentyl, pentyl, hexyl, and perfluorohexyl groups.
R ^a32 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group, or an ethyl group, and even more preferably a hydrogen atom or a methyl group.
Examples of alkyl groups in R ^a33 include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and hexyl groups. The alkyl group is preferably a C1-C4 alkyl group, more preferably a methyl or ethyl group, and even more preferably a methyl group.
Examples of alkoxy groups in R ^a33 include methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, and tert-butoxy groups. The alkoxy group is preferably a carbon-1 to carbon-4 alkoxy group, more preferably a methoxy or ethoxy group, and even more preferably a methoxy group.
Examples of alkoxyalkyl groups in R ^a33 include methoxymethyl group, ethoxyethyl group, propoxymethyl group, isopropoxymethyl group, butoxymethyl group, sec-butoxymethyl group, and tert-butoxymethyl group. The alkoxyalkyl group is preferably an alkoxyalkyl group having 2 to 8 carbon atoms, more preferably a methoxymethyl group or an ethoxyethyl group, and even more preferably a methoxymethyl group.
Examples of alkoxyalkoxy groups in R ^a33 include methoxymethoxy group, methoxyethoxy group, ethoxymethoxy group, ethoxyethoxy group, propoxymethoxy group, isopropoxymethoxy group, butoxymethoxy group, sec-butoxymethoxy group, and tert-butoxymethoxy group. The alkoxyalkoxy group is preferably an alkoxyalkoxy group having 2 to 8 carbon atoms, and more preferably a methoxyethoxy group or an ethoxyethoxy group.
Examples of alkylcarbonyl groups in R ^a33 include acetyl groups, propionyl groups, and butyryl groups. The alkylcarbonyl group is preferably one having 2 to 3 carbon atoms, and more preferably an acetyl group.
Examples of alkylcarbonyloxy groups in R ^a33 include acetyloxy groups, propionyloxy groups, and butyryloxy groups. The alkylcarbonyloxy group is preferably an alkylcarbonyloxy group having 2 to 3 carbon atoms, and more preferably an acetyloxy group.
R ^a33 is preferably a halogen atom, a hydroxyl group, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C2-C8 alkoxyalkoxy group; more preferably a fluorine atom, an iodine atom, a hydroxyl group, a methyl group, a methoxy group, an ethoxy group, an ethoxyethoxy group, or an ethoxymethoxy group; and even more preferably a fluorine atom, an iodine atom, a hydroxyl group, a methyl group, a methoxy group, or an ethoxyethoxy group.

Examples of *-X ^a31- (A ^a32 -X ^a32 ) _nc- include *-O-, *-CO-O-, *-O-CO-, *-CO-O-A ^a32 -CO-O-, *-O-CO-A ^a32 -O-, *-O-A ^a32 -CO-O-, *-CO-O-A ^a32 -O-CO-, and *-O-CO-A ^a32 -O-CO-. Among these, *-CO-O-, *-CO-O-A ^a32 -CO-O-, or *-O-A ^a32 -CO-O- are preferred.
Examples of alkanediyl groups in A ^a32 include methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.
A ^a32 is preferably a methylene group or an ethylene group.
A ^a30 is preferably a single bond, *-CO-O- or *-CO-O-A ^a32 -CO-O-, more preferably a single bond, *-CO-O- or *-CO-O- _CH2 -CO-O-, and even more preferably a single bond or *-CO-O-.

la is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0.
Examples of hydrocarbon groups in R ^a34 , R ^a35 , and R ^a36 include alkyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups combining these.
Examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl groups.
Alicyclic hydrocarbon groups may be monocyclic or polycyclic. Examples of monocyclic alicyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Examples of polycyclic alicyclic hydrocarbon groups include decahydronaphthyl, adamantyl, norbornyl, and the following groups (* indicates a bonding site).
Examples of aromatic hydrocarbon groups include aryl groups such as phenyl, naphthyl, anthryl, biphenyl, and phenanthryl groups.
Examples of combined groups include groups that combine the alkyl group and alicyclic hydrocarbon group as described above (for example, alkylcycloalkyl groups or cycloalkylalkyl groups such as methylcyclohexyl group, dimethylcyclohexyl group, methylnorbornyl group, cyclohexylmethyl group, adamantylmethyl group, adamantyldimethyl group, norbornylethyl group, etc.), aralkyl groups such as benzyl group, aromatic hydrocarbon groups having alkyl groups (p-methylphenyl group, p-tert-butylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups having alicyclic hydrocarbon groups (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), and aryl-cycloalkyl groups such as phenylcyclohexyl group. In particular, R ^a36 can be alkyl groups having 1 to 18 carbon atoms, alicyclic hydrocarbon groups having 3 to 18 carbon atoms, aromatic hydrocarbon groups having 6 to 18 carbon atoms, or groups formed by combining these.

R ^a34 is preferably a hydrogen atom.
R ^a35 is preferably a hydrogen atom, a C1-C12 alkyl group, or a C3-C12 alicyclic hydrocarbon group, and more preferably a methyl group or an ethyl group.
The hydrocarbon group of R ^a36 is preferably an alkyl group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group formed by a combination thereof, and more preferably an alkyl group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms. The alkyl group and alicyclic hydrocarbon group in ^{R a36} are preferably unsubstituted. The aromatic hydrocarbon group in ^{R a36} is preferably an aromatic ring having an aryloxy group having 6 to 10 carbon atoms.
In structural units (a1-4), -OC(R ^a34 )(R ^a35 )-O-R ^a36 is eliminated upon contact with an acid (e.g., p-toluenesulfonic acid) to form a hydroxyl group.
-OC(R ^a34 )(R ^a35 )-O-R ^a36 is preferably bonded to the ortho- or para-position of the benzene ring, and more preferably bonded to the para-position.

Examples of structural units (a1-4) include monomer-derived structural units described in Japanese Patent Publication No. 2010-204646. Preferably, examples include structural units represented by formulas (a1-4-1) to (a1-4-24) and structural units in which the hydrogen atom corresponding to R ^a32 in structural unit (a1-4) is replaced by a halogen atom, a haloalkyl group, or an alkyl group. More preferably, examples include structural units represented by formulas (a1-4-1) to (a1-4-5), (a1-4-10), (a1-4-13), (a1-4-14), (a1-4-19), and (a1-4-20).

When resin (A) contains structural units (a1-4), the content of these units is preferably 3 to 80 mol%, more preferably 5 to 75 mol%, even more preferably 7 to 70 mol%, even more preferably 7 to 65 mol%, and even more preferably 10 to 60 mol% relative to the total amount of all structural units in resin (A).

Structural units derived from (meth)acrylic monomers having group (2) include the structural unit represented by formula (a1-5) (hereinafter sometimes referred to as "structural unit (a1-5)").
In formula (a1-5),
R ^a8 represents a C1-C6 alkyl group, a hydrogen atom, or a halogen atom, which may contain a halogen atom.
Z ^a1 represents a single bond or *-( _CH2 ) _h3 -CO- ^L54- , h3 represents an integer from 1 to 4, and * represents the bond site with ^L51 .
L ⁵¹ , L ⁵² , L ⁵³ , and L ⁵⁴ each independently represent -O- or -S-.
s1 represents an integer between 1 and 3.
s1' represents an integer between 0 and 3.

Examples of halogen atoms include fluorine atoms and chlorine atoms, with fluorine atoms being preferred.
Examples of C1-C6 alkyl groups that may contain halogen atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, fluoromethyl, and trifluoromethyl groups.
In formula (a1-5), ^Ra8 is preferably a hydrogen atom, a methyl group, or a trifluoromethyl group.
L ⁵¹ is preferably an oxygen atom.
It is preferable that one of L ⁵² and L ⁵³ is -O- and the other is -S-.
s1 is preferably 1.
s1' is preferably an integer between 0 and 2.
Z ^a1 is preferably a single bond or * _-CH2 -CO-O-.

Examples of structural units (a1-5) include monomer-derived structural units described in Japanese Patent Publication No. 2010-61117. Among these, structural units represented by formulas (a1-5-1) to (a1-5-4) are preferred, and structural units represented by formula (a1-5-1) or formula (a1-5-2) are more preferred.

When resin (A) contains structural units (a1-5), the content is preferably 1 to 50 mol%, more preferably 3 to 45 mol%, even more preferably 5 to 40 mol%, and even more preferably 5 to 30 mol%, relative to the total structural units of resin (A).

Furthermore, the following structural units can also be listed as structural units (a1).

When resin (A) contains structural units such as (a1-3-1) to (a1-3-7) above, the content of these structural units is preferably 10 to 95 mol%, more preferably 15 to 90 mol%, even more preferably 20 to 85 mol%, even more preferably 20 to 70 mol%, and particularly preferably 20 to 60 mol% relative to the total structural units of resin (A).

Furthermore, the following structural units can also be listed as structural units (a1).
When resin (A) contains structural units such as (a1-6-1) to (a1-6-3) above, the content of these structural units is preferably 10 to 60 mol%, more preferably 15 to 55 mol%, even more preferably 20 to 50 mol%, even more preferably 20 to 45 mol%, and particularly preferably 20 to 40 mol% relative to the total structural units of resin (A).

<Structural unit (s)>
The structural unit (s) is derived from a monomer that does not have an acid-unstable group (hereinafter sometimes referred to as "monomer (s)"). The monomer used to derive the structural unit (s) can be any monomer known in the resist field that does not have an acid-unstable group.
The structural unit (s) preferably has a hydroxyl group or a lactone ring. If a resin containing a structural unit having a hydroxyl group and not having an acid-unstable group (hereinafter sometimes referred to as "structural unit (a2)") and/or a structural unit having a lactone ring and not having an acid-unstable group (hereinafter sometimes referred to as "structural unit (a3)") is used in the resist composition of the present invention, the resolution of the resist pattern and the adhesion to the substrate can be improved.

<Structural Unit (a2)>
The hydroxyl group in structural unit (a2) may be either an alcoholic hydroxyl group or a phenolic hydroxyl group.
When manufacturing a resist pattern from the resist composition of the present invention, if a high-energy beam such as a KrF excimer laser (248 nm), electron beam, or EUV (ultra-ultraviolet light) is used as the exposure light source, a structural unit (a2) having a phenolic hydroxyl group is preferred, and it is more preferable to use the structural unit (a2-A) described later. Furthermore, if an ArF excimer laser (193 nm) or the like is used, a structural unit (a2) having an alcoholic hydroxyl group is preferred, and it is more preferable to use the structural unit (a2-1) described later. The structural unit (a2) may consist of one type alone, or it may consist of two or more types.

A structural unit having a phenolic hydroxyl group in structural unit (a2) is the structural unit represented by formula (a2-A) (hereinafter sometimes referred to as "structural unit (a2-A)").
[In formula (a2-A),
R ^a50 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
R ^a51 represents a halogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C12 alkoxyalkyl group, a C2-C12 alkoxyalkoxy group, a C2-C4 alkylcarbonyl group, a C2-C4 alkylcarbonyloxy group, an acryloyloxy group, or a methacryloyloxy group.
A ^a50 represents a single bond or *-X ^a51- (A ^a52 -X ^a52 ) _nb- , where * represents the bonding site with the carbon atom to which -R ^a50 is bonded.
A ^a52 represents an alkanediyl group with 1 to 6 carbon atoms.
X ^a51 and X ^a52 independently represent -O-, -CO-O-, or -O-CO-, respectively.
nb represents either 0 or 1.
mb represents an integer between 0 and 4. If mb is an integer greater than or equal to 2, multiple R ^a51s may be identical or different from each other.

Examples of halogen atoms in R ^a50 and R ^a51 include fluorine atoms, chlorine atoms, and bromine atoms.
Examples of C1-C6 alkyl groups that may have halogen atoms in R ^a50 include trifluoromethyl group, difluoromethyl group, methyl group, perfluoroethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, ethyl group, perfluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, propyl group, perfluorobutyl group, 1,1,2,2,3,3,4,4-octafluorobutyl group, butyl group, perfluoropentyl group, 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, pentyl group, hexyl group, and perfluorohexyl group.
R ^a50 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group, or an ethyl group, and even more preferably a hydrogen atom or a methyl group.
Examples of alkyl groups in R ^a51 include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and hexyl groups. The alkyl group is preferably a C1-C4 alkyl group, more preferably a methyl or ethyl group, and even more preferably a methyl group.
Examples of alkoxy groups in R ^a51 include methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, and tert-butoxy groups. The alkoxy group is preferably a carbon-1 to carbon-4 alkoxy group, more preferably a methoxy or ethoxy group, and even more preferably a methoxy group.
Examples of alkoxyalkyl groups in R ^a51 include methoxymethyl group, ethoxyethyl group, propoxymethyl group, isopropoxymethyl group, butoxymethyl group, sec-butoxymethyl group, and tert-butoxymethyl group. The alkoxyalkyl group is preferably an alkoxyalkyl group having 2 to 8 carbon atoms, more preferably a methoxymethyl group or an ethoxyethyl group, and even more preferably a methoxymethyl group.
Examples of alkoxyalkoxy groups in R ^a51 include methoxymethoxy group, methoxyethoxy group, ethoxymethoxy group, ethoxyethoxy group, propoxymethoxy group, isopropoxymethoxy group, butoxymethoxy group, sec-butoxymethoxy group, and tert-butoxymethoxy group. The alkoxyalkoxy group is preferably an alkoxyalkoxy group having 2 to 8 carbon atoms, and more preferably a methoxyethoxy group or an ethoxyethoxy group.
Examples of alkylcarbonyl groups in R ^a51 include acetyl groups, propionyl groups, and butyryl groups. The alkylcarbonyl group is preferably one having 2 to 3 carbon atoms, and more preferably an acetyl group.
Examples of alkylcarbonyloxy groups in R ^a51 include acetyloxy groups, propionyloxy groups, and butyryloxy groups. The alkylcarbonyloxy group is preferably an alkylcarbonyloxy group having 2 to 3 carbon atoms, and more preferably an acetyloxy group.
R ^a51 is preferably a halogen atom, a hydroxyl group, a C1-C4 alkyl group, a C1-C4 alkoxy group, or a C2-C8 alkoxyalkoxy group; more preferably a fluorine atom, an iodine atom, a hydroxyl group, a methyl group, a methoxy group, an ethoxy group, an ethoxyethoxy group, or an ethoxymethoxy group; and even more preferably a fluorine atom, an iodine atom, a hydroxyl group, a methyl group, a methoxy group, or an ethoxyethoxy group.

Examples of *-X ^a51- (A ^a52 -X ^a52 ) _nb- include *-O-, *-CO-O-, *-O-CO-, *-CO-O-A ^a52 -CO-O-, *-O-CO-A ^a52 -O-, *-O-A ^a52 -CO-O-, *-CO-O-A ^a52 -O-CO-, and *-O-CO-A ^a52 -O-CO-. Among these, *-CO-O-, *-CO-O-A ^a52 -CO-O-, or *-O-A ^a52 -CO-O- are preferred.
Examples of alkanediyl groups in A ^a52 include methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.
A ^a52 is preferably a methylene group or an ethylene group.
A ^a50 is preferably a single bond, *-CO-O- or *-CO-O-A ^a52 -CO-O-, more preferably a single bond, *-CO-O- or *-CO-O- _CH2 -CO-O-, and even more preferably a single bond or *-CO-O-.

MB is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0.
Preferably, at least one hydroxyl group is bonded to the m- or p-position of the benzene ring, and more preferably to the m-position. If the phenyl group has two or more hydroxyl groups, it is preferable that the two hydroxyl groups are bonded to the m- and p-positions, respectively.

Examples of structural units (a2-A) include monomer-derived structural units described in Japanese Patent Publication No. 2010-204634 and Japanese Patent Publication No. 2012-12577.

Structural units (a2-A) include structural units represented by formulas (a2-2-1) to (a2-2-24) and structural units in which the methyl group corresponding to R ^a50 in structural unit (a2-A) is replaced by a hydrogen atom, a halogen atom, a haloalkyl group, or another alkyl group. Structural units (a2-A) include structural units represented by formulas (a2-2-1) to (a2-2-4), structural units represented by formula (a2-2-6), structural units represented by formula (a2-2-8), and structural units represented by formulas (a2-2-12) to (a2-2-18), and in these structural units, R Preferably, the structural unit is one in which the methyl group corresponding to ^a50 is replaced by a hydrogen atom, and in the structural unit represented by formula (a2-2-3), the structural unit represented by formula (a2-2-4), the structural unit represented by formula (a2-2-8), the structural unit represented by formulas (a2-2-12) to (a2-2-14), the structural unit represented by formula (a2-2-18), and the structural unit represented by formula (a2-2-3), the structural unit represented by formula (a2-2-4), the structural unit represented by formula (a2-2-8), the structural unit represented by formulas (a2-2-12) to (a2-2-14), and the structural unit represented by formula (a2-2-18), R in structural unit (a2-A) It is more preferable that the structural unit is one in which the methyl group corresponding to ^a50 is replaced by a hydrogen atom, and in the structural units represented by formula (a2-2-3), formula (a2-2-4), formula (a2-2-8), and the structural units represented by formula (a2-2-3), formula (a2-2-4), and formula (a2-2-8), it is even more preferable that the structural unit is one in which the methyl group corresponding to R ^a50 in structural unit (a2-A) is replaced by a hydrogen atom.

When the resin (A) contains structural units (a2-A), the content of structural units (a2-A) is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, and even more preferably 20 mol% or more, relative to the total structural units. Furthermore, it is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less. Specifically, it is preferably 5 to 80 mol%, more preferably 10 to 70 mol%, even more preferably 15 to 65 mol%, and even more preferably 20 to 65 mol%.
The structural unit (a2-A) can be incorporated into resin (A) by polymerizing using structural unit (a1-4), for example, and then treating with an acid such as p-toluenesulfonic acid. Alternatively, the structural unit (a2-A) can be incorporated into resin (A) by polymerizing using acetoxystyrene, for example, and then treating with an alkali such as tetramethylammonium hydroxide.

A structural unit having an alcoholic hydroxyl group in structural unit (a2) is the structural unit represented by formula (a2-1) (hereinafter sometimes referred to as "structural unit (a2-1)").
In formula (a2-1),
L ^a3 represents -O- or *-O-( _CH2 ) _k2 -CO-O-,
k2 represents an integer between 1 and 7. * represents a bond site with -CO-.
R ^a14 represents a hydrogen atom or a methyl group.
R ^a15 and R ^a16 each independently represent a hydrogen atom, a methyl group, or a hydroxyl group.
o1 represents an integer between 0 and 10.

In formula (a2-1), L ^a3 is preferably -O-, -O-( _CH2 ) _f1 -CO-O- (where f1 represents an integer from 1 to 4), and more preferably -O-.
R ^a14 is preferably a methyl group.
R ^a15 is preferably a hydrogen atom.
R ^a16 is preferably a hydrogen atom or a hydroxyl group.
o1 is preferably an integer from 0 to 3, more preferably 0 or 1.

Examples of structural units (a2-1) include structural units derived from monomers described in Japanese Patent Publication No. 2010-204646. Structural units represented by any of formulas (a2-1-1) to (a2-1-6) are preferred, structural units represented by any of formulas (a2-1-1) to (a2-1-4) are more preferred, and structural units represented by formula (a2-1-1) or (a2-1-3) are even more preferred.

When resin (A) contains structural unit (a2-1), its content is preferably 1 mol% or more, and more preferably 2 mol% or more, relative to the total structural units of resin (A). It is also preferably 45 mol% or less, more preferably 40 mol% or less, more preferably 35 mol% or less, even more preferably 20 mol% or less, and even more preferably 10 mol% or less. Specifically, it is 1 to 45 mol%, preferably 1 to 40 mol%, more preferably 1 to 35 mol%, even more preferably 1 to 20 mol%, and even more preferably 1 to 10 mol%.

<Structural Unit (a3)>
The lactone ring of the structural unit (a3) may be a monocyclic ring such as a β-propiolactone ring, a γ-butyrolactone ring, or a δ-valerolactone ring, or it may be a fused ring of a monocyclic lactone ring and another ring. Preferably, it may be a γ-butyrolactone ring, an adamantane lactone ring, or a bridging ring containing a γ-butyrolactone ring structure (for example, a structural unit represented by the following formula (a3-2)).

The structural unit (a3) is preferably a structural unit represented by formula (a3-1), formula (a3-2), formula (a3-3), or formula (a3-4). One of these may be included alone, or two or more may be included.
[In formulas (a3-1), (a3-2), (a3-3), and (a3-4),
L ^a4 , L ^a5 , and L ^a6 each independently represent a base represented by -O- or *-O-( _CH2 ) _k3 -CO-O- (where k3 is an integer from 1 to 7).
L ^a7 represents -O-, *-OL ^a8 -O-, *-OL ^a8 -CO-O-, *-OL ^a8 -CO-O-L ^a9 -CO-O-, or *-OL ^a8 -O-CO-L ^a9 -O-.
L ^a8 and L ^a9 each independently represent an alkanediyl group having 1 to 6 carbon atoms.
* indicates a bonding site with a carbonyl group.
R ^a18 , R ^a19 , and R ^a20 each independently represent a hydrogen atom or a methyl group.
R ^a24 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
X ^a3 represents _-CH2- or an oxygen atom.
R ^a21 represents an aliphatic hydrocarbon group with 1 to 4 carbon atoms.
^Ra22 , ^Ra23 , and ^Ra25 each independently represent a carboxyl group, a cyano group, or an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
p1 represents an integer between 0 and 5.
q1 represents an integer between 0 and 3.
r1 represents an integer between 0 and 3.
w1 represents an integer between 0 and 8.
When p1, q1, r1 and/or w1 are 2 or more, the multiple R ^a21 , R ^a22 , R ^a23 and/or R ^a25 may be the same or different from each other.

Examples of aliphatic hydrocarbon groups in ^Ra21 , ^Ra22 , ^Ra23 , and ^Ra25 include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, and tert-butyl groups.
Examples of halogen atoms in R ^a24 include fluorine, chlorine, bromine, and iodine atoms.
Examples of alkyl groups in R ^a24 include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and hexyl groups, with alkyl groups having 1 to 4 carbon atoms being preferred, and methyl or ethyl groups being more preferred.
Examples of alkyl groups having a halogen atom in R ^a24 include trifluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluoroisopropyl group, perfluorobutyl group, perfluorosec-butyl group, perfluorotert-butyl group, perfluoropentyl group, perfluorohexyl group, trichloromethyl group, tribromomethyl group, and triiodomethyl group.

Examples of alkanediyl groups in L ^a8 and L ^a9 include methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.

In formulas (a3-1) to (a3-3), L ^a4 to L ^a6 are each independently preferably -O- or *-O-( _CH2 ) _k3 -CO-O-, where k3 is an integer from 1 to 4, more preferably -O- and *-O- _CH2 -CO-O-, and even more preferably an oxygen atom.
R ^a18 to R ^a21 are preferably methyl groups.
^Ra22 and ^Ra23 are each independently preferably a carboxyl group, a cyano group, or a methyl group.
p1, q1, and r1 are each independently, preferably integers from 0 to 2, and more preferably 0 or 1.

In formula (a3-4), R ^a24 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group or an ethyl group, and even more preferably a hydrogen atom or a methyl group.
^Ra25 is preferably a carboxyl group, a cyano group, or a methyl group.
L ^a7 is preferably -O- or *-O-L ^a8 -CO-O-, and more preferably -O-, -O- _CH2 -CO-O- or -O- _{C2H4 -CO} -O-.
w1 is preferably an integer between 0 and 2, and more preferably 0 or 1.
In particular, formula (a3-4) is preferred over formula (a3-4)'.
(In the formula, R ^a24 and L ^a7 have the same meaning as above.)

Examples of structural units (a3) include those derived from monomers described in Japanese Patent Publication No. 2010-204646, Japanese Patent Publication No. 2000-122294, and Japanese Patent Publication No. 2012-41274. Preferred structural units (a3) include those represented by any of the formulas (a3-1-1), (a3-1-2), (a3-2-1), (a3-2-2), (a3-3-1), (a3-3-2), and (a3-4-1) to (a3-4-12), and structural units in which the methyl groups corresponding to R ^a18 , R ^a19 , R ^a20 , and R ^a24 in formulas (a3-1) to (a3-4) are replaced with hydrogen atoms.

When resin (A) contains structural units (a3), the total content is 1 mol% or more, preferably 3 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total structural units of resin (A). Alternatively, it may be 70 mol% or less, preferably 65 mol% or less, and more preferably 60 mol% or less. Specifically, it is 1 to 70 mol%, preferably 3 to 65 mol%, and more preferably 5 to 60 mol%.
Furthermore, the content of structural unit (a3-1), structural unit (a3-2), structural unit (a3-3), or structural unit (a3-4) is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, relative to the total structural units of resin (A). Also preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. Specifically, 1 to 60 mol% is preferred, 3 to 50 mol% is more preferred, and 5 to 50 mol% is even more preferred.

<Structural Unit (a4)>
The following structural units (a4) can be considered:
[In formula (a4),
R ⁴¹ represents a hydrogen atom or a methyl group.
R ⁴² represents a saturated hydrocarbon group having a halogen atom with 1 to 24 carbon atoms, and the _-CH2- contained in the saturated hydrocarbon group may be replaced with -O- or -CO-.
The saturated hydrocarbon group represented by R ⁴² includes chain-type saturated hydrocarbon groups, monocyclic or polycyclic alicyclic saturated hydrocarbon groups, and groups formed by combining these.

Examples of chain-type saturated hydrocarbon groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups.
Examples of monocyclic or polycyclic alicyclic saturated hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups; and polycyclic alicyclic saturated hydrocarbon groups such as decahydronaphthyl, adamantyl, norbornyl, and the following groups (* indicates the bonding site).
Examples of groups formed by combinations include groups formed by combining one or more alkyl groups or one or more alkanediyl groups with one or more alicyclic saturated hydrocarbon groups, such as -alkanediyl group-alicyclic saturated hydrocarbon group, -alicyclic saturated hydrocarbon group-alkyl group, and -alkanediyl group-alicyclic saturated hydrocarbon group-alkyl group.

Examples of structural units (a4) include the structural unit represented by formula (a4-0), the structural unit represented by formula (a4-1), and the structural unit represented by formula (a4-4).
[In formula (a4-0),
R ⁵⁴ represents a hydrogen atom or a methyl group.
L ^4a represents a single bond or an alkanediyl group having 1 to 4 carbon atoms.
^L3a represents a perfluoroalkanediyl group having 1 to 8 carbon atoms or a perfluorocycloalkanediyl group having 3 to 12 carbon atoms.
R ⁶⁴ represents a hydrogen atom or a fluorine atom.

Examples of alkanediyl groups in L ^4a include linear alkanediyl groups such as methylene group, ethylene group, propane-1,3-diyl group, and butane-1,4-diyl group, and branched alkanediyl groups such as ethane-1,1-diyl group, propane-1,2-diyl group, butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, and 2-methylpropane-1,2-diyl group.

In L ^3a , the perfluoroalkanediyl group includes difluoromethylene group, perfluoroethylene group, perfluoroethylfluoromethylene group, perfluoropropane-1,3-diyl group, perfluoropropane-1,2-diyl group, perfluoropropane-2,2-diyl group, perfluorobutane-1,4-diyl group, perfluorobutane-2,2-diyl group, perfluorobutane-1,2-diyl group, perfluoropentane-1,5-diyl group, perfluoropentane-2,2-diyl group, and perfluoropentane- Examples include 3,3-diyl group, perfluorohexane-1,6-diyl group, perfluorohexane-2,2-diyl group, perfluorohexane-3,3-diyl group, perfluoroheptane-1,7-diyl group, perfluoroheptane-2,2-diyl group, perfluoroheptane-3,4-diyl group, perfluoroheptane-4,4-diyl group, perfluorooctane-1,8-diyl group, perfluorooctane-2,2-diyl group, perfluorooctane-3,3-diyl group, and perfluorooctane-4,4-diyl group.
Examples of perfluorocycloalkanediyl groups in L ^3a include perfluorocyclohexanediyl group, perfluorocyclopentanediyl group, perfluorocycloheptanediyl group, and perfluoroadamantanediyl group.

L ^4a is preferably a single bond, a methylene group, or an ethylene group, and more preferably a single bond or a methylene group.
^L3a is preferably a perfluoroalkanediyl group having 1 to 6 carbon atoms, and more preferably a perfluoroalkanediyl group having 1 to 3 carbon atoms.

Examples of structural units (a4-0) include the structural units shown below and structural units in which the methyl group corresponding to R ⁵⁴ in structural unit (a4-0) below is replaced by a hydrogen atom.

[In formula (a4-1),
R ^a41 represents a hydrogen atom or a methyl group.
R ^a42 represents a saturated hydrocarbon group having 1 to 20 carbon atoms, which may have substituents, and the _-CH2- contained in the saturated hydrocarbon group may be replaced with -O- or -CO-.
A ^a41 represents an alkanediyl group having 1 to 6 carbon atoms, which may have substituents, or a group represented by formula (a-g1). However, at least one of A ^a41 and R ^a42 has a halogen atom (preferably a fluorine atom) as a substituent.
[In formula (a-g1),
s represents either 0 or 1.
A ^a42 and A ^a44 each independently represent a divalent saturated hydrocarbon group having 1 to 5 carbon atoms, which may have substituents.
A ^a43 represents a divalent saturated hydrocarbon group having 1 to 5 carbon atoms, which may have a single bond or substituents.
X ^a41 and X ^a42 independently represent -O-, -CO-, -CO-O-, or -O-CO-, respectively.
However, the total number of carbon atoms in A ^a42 , A ^a43 , A ^a44 , X ^a41 , and X ^a42 is 7 or less.
* indicates a binding site, and the * on the right is the binding site with -O-CO-R ^a42 .

Examples of saturated hydrocarbon groups in R ^a42 include chain-type saturated hydrocarbon groups, monocyclic or polycyclic alicyclic saturated hydrocarbon groups, and groups formed by combining these.

Examples of chain-type saturated hydrocarbon groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups.
Examples of monocyclic or polycyclic alicyclic saturated hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups; and polycyclic alicyclic saturated hydrocarbon groups such as decahydronaphthyl, adamantyl, norbornyl, and the following groups (* indicates the bonding site).
Examples of groups formed by combinations include groups formed by combining one or more alkyl groups or one or more alkanediyl groups with one or more alicyclic saturated hydrocarbon groups, such as -alkanediyl group-alicyclic saturated hydrocarbon group, -alicyclic saturated hydrocarbon group-alkyl group, and -alkanediyl group-alicyclic saturated hydrocarbon group-alkyl group.

The substituents on R ^a42 include at least one selected from the group consisting of halogen atoms and groups represented by formula (a-g3). Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms being preferred.
[In formula (a-g3),
X ^a43 represents an oxygen atom, a carbonyl group, *-O-CO-, or *-CO-O-.
A ^a45 represents a saturated hydrocarbon group having 1 to 17 carbon atoms, which may contain a halogen atom.
* indicates the binding site with R ^a42 .
However, in R ^a42 - X ^a43 - ^{A a45} , if R ^a42 does not have a halogen atom, then A ^a45 represents a saturated hydrocarbon group having 1 to 17 carbon atoms and having at least one halogen atom.

In A ^a45 , saturated hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl;
Examples include monocyclic alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups, as well as polycyclic alicyclic hydrocarbon groups such as decahydronaphthyl, adamantyl, norbornyl, and the following groups (* indicates the bonding site).
Examples of groups formed by combinations include groups formed by combining one or more alkyl groups or one or more alkanediyl groups with one or more alicyclic hydrocarbon groups, such as -alkanediyl group-alicyclic hydrocarbon group, -alicyclic hydrocarbon group-alkyl group, and -alkanediyl group-alicyclic hydrocarbon group-alkyl group.

R ^a42 is preferably a saturated hydrocarbon group which may have a halogen atom, and more preferably a saturated hydrocarbon group which has an alkyl group having a halogen atom and/or a group represented by formula (a-g3).
When R ^a42 is a saturated hydrocarbon group having a halogen atom, it is preferably a saturated hydrocarbon group having a fluorine atom, more preferably a perfluoroalkyl group or a perfluorocycloalkyl group, even more preferably a perfluoroalkyl group having 1 to 6 carbon atoms, and particularly preferably a perfluoroalkyl group having 1 to 3 carbon atoms. Examples of perfluoroalkyl groups include perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluoroheptyl group, and perfluorooctyl group. Examples of perfluorocycloalkyl groups include perfluorocyclohexyl group.
When R ^a42 is a saturated hydrocarbon group having a group represented by formula (a-g3), the total number of carbon atoms in R ^a42 , including the number of carbon atoms in the group represented by formula (a-g3), is preferably 15 or less, and more preferably 12 or less. If the group represented by formula (a-g3) is present as a substituent, the number of substituents is preferably one.

If R ^a42 is a saturated hydrocarbon group having a group represented by formula (a-g3), then R ^a42 is more preferably a group represented by formula (a-g2).
[In formula (a-g2),
A ^a46 represents a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, which may contain a halogen atom.
X ^a44 represents **-O-CO- or **-CO-O- (where ** represents the bonding site with A ^a46 ).
A ^a47 represents a saturated hydrocarbon group having 1 to 17 carbon atoms, which may contain a halogen atom.
However, the total number of carbon atoms in A ^a46 , A ^a47 , and X ^a44 is 18 or less, and at least one of A ^a46 and A ^a47 has at least one halogen atom.
* indicates the bonding site with the carbonyl group.

The saturated hydrocarbon group of A ^a46 preferably has 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms.
The saturated hydrocarbon group of A ^a47 preferably has 4 to 15 carbon atoms, more preferably 5 to 12, and A ^a47 is even more preferably a cyclohexyl group or an adamantyl group.

The preferred structure of the group represented by formula (a-g2) is as follows (* indicates the bonding site with the carbonyl group).

Examples of alkanediyl groups in A ^a41 include linear alkanediyl groups such as methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group; and branched alkanediyl groups such as propane-1,2-diyl group, butane-1,3-diyl group, 2-methylpropane-1,2-diyl group, 1-methylbutane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.
Examples of substituents on the alkanediyl group represented by A ^a41 include hydroxyl groups and alkoxy groups having 1 to 6 carbon atoms.
A ^a41 is preferably an alkanediyl group having 1 to 4 carbon atoms, more preferably an alkanediyl group having 2 to 4 carbon atoms, and even more preferably an ethylene group.

Examples of divalent saturated hydrocarbon groups represented by A ^a42 , A ^a43 , and A ^a44 in the group represented by formula (a-g1) include linear or branched alkanediyl groups and monocyclic or polycyclic divalent alicyclic saturated hydrocarbon groups, as well as divalent saturated hydrocarbon groups formed by combining alkanediyl groups and divalent alicyclic saturated hydrocarbon groups. Specifically, examples include methylene groups, ethylene groups, propane-1,3-diyl groups, propane-1,2-diyl groups, butane-1,4-diyl groups, 1-methylpropane-1,3-diyl groups, 2-methylpropane-1,3-diyl groups, and 2-methylpropane-1,2-diyl groups.
Examples of substituents on the divalent saturated hydrocarbon groups represented by A ^a42 , A ^a43 , and A ^a44 include hydroxyl groups and alkoxy groups having 1 to 6 carbon atoms.
s is preferably 0.

In the group represented by formula (a-g1), the following groups are examples of groups where X ^a42 is -O-, -CO-, -CO-O-, or -O-CO-. In the following examples, * and ** represent bonding sites, and ** is the bonding site with -O-CO-R ^a42 .

Structural units represented by formula (a4-1) include the structural units shown below and structural units in which the methyl group corresponding to R ^a41 in the structural unit represented by formula (a4-1) below is replaced by a hydrogen atom.

Examples of structural units represented by formula (a4-1) include the structural units represented by formula (a4-2) and the structural units represented by formula (a4-3).
[In formula (a4-2),
R ^f5 represents a hydrogen atom or a methyl group.
L ⁴⁴ represents an alkanediyl group having 1 to 6 carbon atoms, and the _-CH2- contained in the alkanediyl group may be replaced with -O- or -CO-.
R ^f6 represents a saturated hydrocarbon group having 1 to 20 fluorine atoms.
However, the upper limit for the total number of carbon atoms in L ⁴⁴ and R ^f6 is 21.

Examples of the alkanediyl groups with 1 to 6 carbon atoms in L ⁴⁴ include those similar to those exemplified in A ^a41 .
The saturated hydrocarbon group of R ^f6 is similar to the group exemplified in R ⁴² .
In L ⁴⁴ , an alkanediyl group having 2 to 4 carbon atoms is preferred, and an ethylene group is more preferred.

Examples of structural units represented by formula (a4-2) include those represented by formulas (a4-1-1) to (a4-1-11), respectively. Structural units in which the methyl group corresponding to R ^f5 in structural unit (a4-2) is replaced by a hydrogen atom can also be listed as structural units represented by formula (a4-2).

[In formula (a4-3),
R ^f7 represents a hydrogen atom or a methyl group.
^L5 represents an alkanediyl group with 1 to 6 carbon atoms.
A ^f13 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, which may contain a fluorine atom.
X ^f12 represents *-O-CO- or *-CO-O- (where * represents the bonding site with A ^f13 ).
A ^f14 represents a saturated hydrocarbon group having 1 to 17 carbon atoms, which may contain a fluorine atom.
However, at least one of A ^f13 and A ^f14 has a fluorine atom, and the upper limit of the total number of carbon atoms in L ⁵ , A ^f13 , and A ^f14 is 20.

Examples of alkanediyl groups in L ⁵ include those similar to those exemplified in the alkanediyl group of A ^a41 .

In A ^f13 , the optionally fluorine-containing divalent saturated hydrocarbon group is preferably an optionally fluorine-containing divalent chain-type saturated hydrocarbon group and an optionally fluorine-containing divalent alicyclic saturated hydrocarbon group, and more preferably a perfluoroalkanediyl group.
Examples of divalent chain-type saturated hydrocarbon groups that may contain a fluorine atom include methylene groups, ethylene groups, propanediyl groups, butanediyl groups, and pentanediyl groups, as well as perfluoroalkanediyl groups such as difluoromethylene groups, perfluoroethylene groups, perfluoropropanediyl groups, perfluorobutanediyl groups, and perfluoropentanediyl groups.
The divalent alicyclic saturated hydrocarbon group, which may contain a fluorine atom, may be monocyclic or polycyclic. Examples of monocyclic groups include cyclohexanediyl and perfluorocyclohexanediyl groups. Examples of polycyclic groups include adamantanediyl, norbornanediyl, and perfluoroadamantanediyl groups.

A ^f14 may have saturated hydrocarbon groups and saturated hydrocarbon groups having fluorine atoms, and these may be the same groups as those exemplified in R ^a42 . Among them are trifluoromethyl group, difluoromethyl group, methyl group, perfluoroethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, ethyl group, perfluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, propyl group, perfluorobutyl group, 1,1,2,2,3,3,4,4-octafluorobutyl group, butyl group, perfluoropentyl group, 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, pentyl group, Preferred groups include alkyl fluorides such as hexyl group, perfluorohexyl group, heptyl group, perfluoroheptyl group, octyl group, and perfluorooctyl group, cyclopropylmethyl group, cyclopropyl group, cyclobutylmethyl group, cyclopentyl group, cyclohexyl group, perfluorocyclohexyl group, adamantyl group, adamantylmethyl group, adamantyldimethyl group, norbornyl group, norbornylmethyl group, perfluoroadamantyl group, and perfluoroadamantylmethyl group.

In formula (a4-3), ^L5 is preferably an ethylene group.
The divalent saturated hydrocarbon group of A ^f13 is preferably a group containing a divalent chain saturated hydrocarbon group having 1 to 6 carbon atoms and a divalent alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and more preferably a divalent chain saturated hydrocarbon group having 2 to 3 carbon atoms.
The saturated hydrocarbon group of A ^f14 is preferably a group containing a chain-type saturated hydrocarbon group having 3 to 12 carbon atoms and an alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and more preferably a group containing a chain-type saturated hydrocarbon group having 3 to 10 carbon atoms and an alicyclic saturated hydrocarbon group having 3 to 10 carbon atoms. In particular, A ^f14 is preferably a group containing an alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and more preferably a cyclopropylmethyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group.

Examples of structural units represented by formula (a4-3) include those represented by formulas (a4-1'-1) to (a4-1'-11), respectively. Structural units in which the methyl group corresponding to R ^f7 in structural unit (a4-3) is replaced with a hydrogen atom can also be cited as structural units represented by formula (a4-3).

Another example of a structural unit (a4) is the structural unit represented by formula (a4-4).
[In formula (a4-4),
R ^f21 represents a hydrogen atom or a methyl group.
A ^f21 represents -( _CH2 ) _j1- , -( _CH2 ) _j2 -O-( _CH2 ) _j3- , or -( _CH2 ) _j4 -CO-O-( _CH2 ) _j5- .
j1 through j5 each independently represent an integer from 1 to 6.
R ^f22 represents a saturated hydrocarbon group having 1 to 10 carbon atoms and containing a fluorine atom.

The saturated hydrocarbon group of R ^f22 is similar to the saturated hydrocarbon group represented by R ^a42 . ^{R f22} is preferably an alkyl group having 1 to 10 carbon atoms and a fluorine atom, or an alicyclic saturated hydrocarbon group having 1 to 10 carbon atoms and a fluorine atom, more preferably an alkyl group having 1 to 10 carbon atoms and a fluorine atom, and even more preferably an alkyl group having 1 to 6 carbon atoms and a fluorine atom.

In formula (a4-4), A ^f21 is preferably -( _CH2 ) _j1- , more preferably an ethylene group or a methylene group, and even more preferably a methylene group.

Examples of structural units represented by formula (a4-4) include the following structural units and structural units in which the methyl group corresponding to R ^f21 in structural unit (a4-4) is replaced by a hydrogen atom.

If resin (A) contains structural units (a4), the content of these units is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, and even more preferably 3 to 10 mol%, relative to the total structural units of resin (A).

<Structural Unit (a5)>
Examples of non-eliminating hydrocarbon groups in structural unit (a5) include groups having linear, branched, or cyclic hydrocarbon groups. Among these, structural unit (a5) is preferably a group having an alicyclic hydrocarbon group.
An example of a structural unit (a5) is the structural unit represented by formula (a5-1).
[In formula (a5-1),
R ⁵¹ represents a hydrogen atom or a methyl group.
R ⁵² represents an alicyclic hydrocarbon group having 3 to 18 carbon atoms, and the hydrogen atoms contained in the alicyclic hydrocarbon group may be substituted with an aliphatic hydrocarbon group having 1 to 8 carbon atoms.
L ⁵⁵ represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and the _-CH2- contained in the saturated hydrocarbon group may be replaced with -O- or -CO-.

The alicyclic hydrocarbon group in R ⁵² may be either monocyclic or polycyclic. Examples of monocyclic alicyclic hydrocarbon groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. Examples of polycyclic alicyclic hydrocarbon groups include adamantyl and norbornyl groups.
Examples of aliphatic hydrocarbon groups having 1 to 8 carbon atoms include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, and 2-ethylhexyl.
Examples of alicyclic hydrocarbon groups having substituents include the 3-methyladamantyl group.
R ⁵² is preferably an unsubstituted alicyclic hydrocarbon group having 3 to 18 carbon atoms, and more preferably an adamantyl group, a norbornyl group, or a cyclohexyl group.

Examples of divalent saturated hydrocarbon groups in L ⁵⁵ include divalent chain saturated hydrocarbon groups and divalent alicyclic saturated hydrocarbon groups, with divalent chain saturated hydrocarbon groups being preferred.
Examples of divalent chain-type saturated hydrocarbon groups include methylene groups, ethylene groups, propanediyl groups, butanediyl groups, and pentanediyl groups, as well as other alkanediyl groups.
The divalent alicyclic saturated hydrocarbon group may be monocyclic or polycyclic. Examples of monocyclic alicyclic saturated hydrocarbon groups include cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl. Examples of polycyclic divalent alicyclic saturated hydrocarbon groups include adamantanediyl and norbornanediyl.

Groups in which the _-CH2- contained in the divalent saturated hydrocarbon group represented by L ⁵⁵ is replaced with -O- or -CO- include, for example, the groups represented by formulas (L1-1) to (L1-4). In the following formulas, * and ** represent bonding sites, respectively, and * represents the bonding site with the oxygen atom.
In formula (L1-1),
X ^x1 represents *-O-CO- or *-CO-O- (where * represents the bonding site with L ^x1 ).
L ^x1 represents a divalent aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms.
L ^x2 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 15 carbon atoms.
However, the total number of carbon atoms in L ^x1 and L ^x2 must be 16 or less.
In formula (L1-2),
L ^x3 represents a divalent aliphatic saturated hydrocarbon group with 1 to 17 carbon atoms.
L ^x4 represents a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms.
However, the total number of carbon atoms in L ^x3 and L ^x4 must be 17 or less.
In formula (L1-3),
L ^x5 represents a divalent aliphatic saturated hydrocarbon group with 1 to 15 carbon atoms.
L ^x6 and L ^x7 each independently represent a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 14 carbon atoms.
However, the total number of carbon atoms in L ^{x 5} , L ^{x 6} , and L ^{x 7} must be 15 or less.
In formula (L1-4),
L ^x8 and L ^x9 represent a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 12 carbon atoms.
W ^x1 represents a divalent alicyclic saturated hydrocarbon group having 3 to 15 carbon atoms.
However, the total number of carbon atoms in L ^x8 , L ^x9 , and W ^x1 is 15 or less.

L ^x1 is preferably a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a methylene group or an ethylene group.
L ^x2 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a single bond.
L ^x3 is preferably a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^x4 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^x5 is preferably a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a methylene group or an ethylene group.
L ^x6 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a methylene group or an ethylene group.
L ^x7 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms.
L ^x8 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a single bond or a methylene group.
L ^x9 is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 to 8 carbon atoms, more preferably a single bond or a methylene group.
W ^x1 is preferably a divalent alicyclic saturated hydrocarbon group having 3 to 10 carbon atoms, more preferably a cyclohexanediyl group or an adamantanediyl group.

Examples of groups represented by formula (L1-1) include the divalent groups shown below.

Examples of groups represented by formula (L1-2) include the divalent groups shown below.

Examples of groups represented by formula (L1-3) include the divalent groups shown below.

Examples of groups represented by formula (L1-4) include the divalent groups shown below.

L ⁵⁵ is preferably a single bond or a group represented by formula (L1-1).

Examples of structural units (a5-1) include the structural units shown below and structural units in which the methyl group corresponding to R ⁵¹ in structural unit (a5-1) below is replaced by a hydrogen atom.
If the resin (A) contains structural units (a5), the content of these units is preferably 1 to 30 mol%, more preferably 2 to 20 mol%, and even more preferably 3 to 15 mol%, relative to the total structural units of the resin (A).

<Structural Unit (a6)>
The structural unit (a6) is a structural unit having a _-SO₂- group, and it is preferable that the _-SO₂- group is present in the side chain.
A structural unit having an _-SO₂- group may have a linear structure having an _-SO₂- group, a branched structure having an _-SO₂- group, or a cyclic structure (monocyclic and polycyclic) having an _-SO₂- group. Preferably, it is a structural unit having a cyclic structure having an _-SO₂- group, and more preferably, it is a structural unit having a cyclic structure (sultone ring) containing _-SO₂- O-.

Examples of sultone rings include those represented by the following formulas ( ^T1-1 ), ( ^T1-2 ), ( ^T1-3 ), and ( ^T1-4 ). The bonding site can be at any position. The sultone ring may be monocyclic, but it is preferably polycyclic. A polycyclic sultone ring means a bridging ring containing -SO₂ _- O- as the atomic group constituting the ring, and examples include the rings represented by formulas ( ^T1-1 ) and ( ^T1-2 ). The sultone ring, as in the ring represented by formula ( ^T1-2 ), may also contain heteroatoms in addition to _-SO₂- O- as the atomic group constituting the ring. Examples of heteroatoms include oxygen atoms, sulfur atoms, or nitrogen atoms, and oxygen atoms are preferred.

The sultone ring may have substituents. Examples of substituents include C1-C12 alkyl groups (which may have a halogen atom or a hydroxyl group), halogen atoms, hydroxyl groups, cyano groups, C1-C12 alkoxy groups, C6-C12 aryl groups, C7-C12 aralkyl groups, glycidyloxy groups, C2-C12 alkoxycarbonyl groups, and C2-C4 alkylcarbonyl groups.

Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.
Examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and decyl groups, preferably alkyl groups having 1 to 6 carbon atoms, and more preferably methyl groups.
Examples of alkyl groups having a halogen atom include trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl, and triiodomethyl, with trifluoromethyl being preferred.
Examples of alkyl groups having a hydroxyl group include hydroxymethyl groups and 2-hydroxyethyl groups.
Examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy, and dodecyloxy groups.
Examples of aryl groups include phenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl, cumyl, mesityl, biphenyl, phenanthryl, 2,6-diethylphenyl, and 2-methyl-6-ethylphenyl.
Examples of aralkyl groups include benzyl, phenethyl, phenylpropyl, naphthylmethyl, and naphthylethyl groups.
Examples of alkoxycarbonyl groups include groups in which an alkoxy group such as a methoxycarbonyl group or an ethoxycarbonyl group is bonded to a carbonyl group, preferably an alkoxycarbonyl group having 6 or fewer carbon atoms, and more preferably a methoxycarbonyl group.
Examples of alkylcarbonyl groups include acetyl, propionyl, and butyryl groups.

From the viewpoint of ease of producing monomers that lead to structural unit (a6), a sultone ring without substituents is preferred.
As the sultone ring, the ring represented by the following formula (T1') is preferred.
[In formula (T1'),
^X11 represents an oxygen atom, a sulfur atom, or a methylene group.
R ⁴¹ represents a C1-C12 alkyl group which may have a halogen atom or a hydroxyl group, a halogen atom, a hydroxyl group, a cyano group, a C1-C12 alkoxy group, a C6-C12 aryl group, a C7-C12 aralkyl group, a glycidyloxy group, a C2-C12 alkoxycarbonyl group, or a C2-C4 alkylcarbonyl group.
ma represents an integer from 0 to 9. When ma is 2 or greater, multiple R ^41s may be the same or different.
The connection site can be at any position.
X ¹¹ is preferably an oxygen atom or a methylene group, and more preferably a methylene group.
Examples of R ⁴¹ include substituents similar to those of the sultone ring, and a C1 to C12 alkyl group which may have a halogen atom or a hydroxyl group is preferred.

As the sultone ring, the ring represented by formula (T1) is more preferable.
[In formula (T1),
^R8 represents a C1-C12 alkyl group which may have a halogen atom or a hydroxyl group, a halogen atom, a hydroxyl group, a cyano group, a C1-C12 alkoxy group, a C6-C12 aryl group, a C7-C12 aralkyl group, a glycidyloxy group, a C2-C12 alkoxycarbonyl group, or a C2-C4 alkylcarbonyl group.
m represents an integer from 0 to 9. When m is 2 or greater, multiple ^R8s may be the same or different.
The connection site can be at any position.
R ⁸ is similar to R ⁴¹ .
In formula (T1'), ma and in formula (T1), m are preferably 0 or 1, and more preferably 0.

The following rings are examples of rings represented by formula (T1') and formula (T1). The bonding site is at an arbitrary position.

Structural units having a sultone ring preferably have the following groups. * in the following groups indicates a bonding site.

The structural unit having the _-SO2- group preferably further has a group derived from a polymerizable group. Examples of polymerizable groups include vinyl group, acryloyl group, methacryloyl group, acryloyloxy group, methacryloyloxy group, acryloylamino group, methacryloylamino group, acryloylthio group, and methacryloylthio group.
In particular, the monomer that leads to the structural unit (a6) is preferably a monomer having an ethylenically unsaturated bond, and more preferably a (meth)acrylic monomer.

The structural unit (a6) is preferably a structural unit represented by formula (Ix).
[In formula (Ix), ^Rx represents a C1-C6 alkyl group, a hydrogen atom, or a halogen atom which may have a halogen atom.
^Axx represents an oxygen atom, a -N( ^Rc )- atom, or a sulfur atom.
^Ax represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and _{the -CH2-} contained in the saturated hydrocarbon group may be replaced with -O-, -CO-, or -N( ^Rd )-.
^X11 represents an oxygen atom, a sulfur atom, or a methylene group.
R ⁴¹ represents a C1-C12 alkyl group which may have a halogen atom or a hydroxyl group, a halogen atom, a hydroxyl group, a cyano group, a C1-C12 alkoxy group, a C6-C12 aryl group, a C7-C12 aralkyl group, a glycidyloxy group, a C2-C12 alkoxycarbonyl group, or a C2-C4 alkylcarbonyl group.
ma represents an integer from 0 to 9. When ma is 2 or greater, multiple R ^41s may be the same or different.
^Rc and ^Rd independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

Examples of halogen atoms in ^Rx include fluorine, chlorine, bromine, and iodine.
Examples of alkyl groups for R ^x include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, and n-hexyl group, preferably alkyl groups having 1 to 4 carbon atoms, and more preferably methyl group or ethyl group.
Examples of alkyl groups having a halogen atom of R ^x include trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoroisopropyl, perfluorobutyl, perfluorosec-butyl, perfluorotert-butyl, perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl, and triiodomethyl.
^Rx is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group, or an ethyl group, and even more preferably a hydrogen atom or a methyl group.

Examples of the divalent saturated hydrocarbon group A ^x include linear alkanediyl groups, branched alkanediyl groups, and monocyclic or polycyclic divalent alicyclic saturated hydrocarbon groups, and combinations of two or more of these groups are also acceptable.
Specifically, methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group Linear alkane diyl groups such as dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, ethane-1,1-diyl group, propane-1,1-diyl group, and propane-2,2-diyl group;
Branched alkanediyl groups such as butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group;
Monocyclic, divalent, alicyclic saturated hydrocarbon groups such as cycloalkanediyl groups, cyclobutane-1,3-diyl groups, cyclopentane-1,3-diyl groups, cyclohexane-1,4-diyl groups, and cyclooctane-1,5-diyl groups;
Examples include polycyclic divalent alicyclic saturated hydrocarbon groups such as norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-1,5-diyl group, and adamantane-2,6-diyl group.
R ⁴¹ , X ¹¹ , and ma are the same as those in formula (T1').
Examples of sultone rings include those mentioned above, and among them, those with specified bonding positions are preferred.

The following structural units (a6) are examples of structural units:

In particular, structural units represented by formulas (a6-1), (a6-2), (a6-6), (a6-7), (a6-8), and (a6-12) are preferred, and structural units represented by formulas (a6-1), (a6-2), (a6-7), and (a6-8) are more preferred.
If the resin (A) has structural units (a6), the content of these units is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, and even more preferably 3 to 30 mol%, relative to the total structural units of the resin (A).

<Structural Unit (II)>
The resin (A) may further contain structural units that decompose upon exposure to generate acid (hereinafter sometimes referred to as "structural unit (II)"). Specifically, structural unit (II) is the structural unit described in Japanese Patent Application Publication No. 2016-79235, and is preferably a structural unit having a sulfonate group or carboxylate group and an organic cation in its side chain, or a structural unit having a sulfonio group and an organic anion in its side chain.

The structural unit having a sulfonate group or carboxylate group and an organic cation in its side chain is preferably the structural unit represented by formula (II-2-A').
[In formula (II-2-A'),
^XIII3 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and the _-CH2- contained in the saturated hydrocarbon group may be replaced with -O-, -S-, or -CO-, and the hydrogen atom contained in the saturated hydrocarbon group may be replaced with a halogen atom, an alkyl group having 1 to 6 carbon atoms which may contain a halogen atom, or a hydroxyl group.
A ^x1 represents an alkanediyl group having 1 to 8 carbon atoms, and the hydrogen atoms contained in the alkanediyl group may be substituted with fluorine atoms or perfluoroalkyl groups having 1 to 6 carbon atoms.
^RA- represents a sulfonate group or a carboxylate group.
R ^III3 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
ZA ⁺ represents an organic cation.

Examples of halogen atoms represented by R ^III3 include fluorine, chlorine, bromine, and iodine atoms.
Examples of C1-C6 alkyl groups that may have a halogen atom represented by R ^III3 are the same as C1-C6 alkyl groups that may have a halogen atom represented by R ^a8 .
Examples of ^C1 -C1 alkanediyl groups include methylene group, ethylene group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, ethane-1,1-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-2,2-diyl group, pentane-2,4-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group.
Examples of C1-C6 perfluoroalkyl groups that may be substituted in A ^x1 include trifluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluoroisopropyl group, perfluorobutyl group, perfluorosec-butyl group, perfluorotert-butyl group, perfluoropentyl group, and perfluorohexyl group.

Examples of divalent saturated hydrocarbon groups having 1 to 18 carbon atoms represented by X ^III3 include linear or branched alkanediyl groups, monocyclic or polycyclic divalent alicyclic saturated hydrocarbon groups, and combinations thereof.
Specifically, linear alkanediyl groups such as methylene group, ethylene group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group; branched alkanediyl groups such as butane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, 2-methylbutane-1,4-diyl group;
Divalent monocyclic or alicyclic saturated hydrocarbon groups such as cycloalkanediyl groups including cyclobutane-1,3-diyl, cyclopentane-1,3-diyl, cyclohexane-1,4-diyl, and cyclooctane-1,5-diyl;
Examples include divalent polycyclic alicyclic saturated hydrocarbon groups such as norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-1,5-diyl group, and adamantane-2,6-diyl group.

Examples of groups in which the _-CH2- contained in a saturated hydrocarbon group is replaced by -O-, -S-, or -CO- include the divalent groups represented by formulas (X1) to (X53). However, the number of carbon atoms before the _-CH2- contained in the saturated hydrocarbon group is replaced by -O-, -S-, or -CO- is 17 or less. In the following formulas, * and ** represent bonding sites, and * represents the bonding site with A ^x1 .

^X3 represents a divalent saturated hydrocarbon group having 1 to 16 carbon atoms.
^X4 represents a divalent saturated hydrocarbon group having 1 to 15 carbon atoms.
^X5 represents a divalent saturated hydrocarbon group having 1 to 13 carbon atoms.
^X6 represents a divalent saturated hydrocarbon group having 1 to 14 carbon atoms.
^X7 represents a trivalent saturated hydrocarbon group having 1 to 14 carbon atoms.
^X8 represents a divalent saturated hydrocarbon group having 1 to 13 carbon atoms.

Examples of organic cations represented by ZA ⁺ include organic onium cations, organic sulfonium cations, organic iodonium cations, organic ammonium cations, benzothiazolium cations, and organic phosphonium cations. Among these, organic sulfonium cations and organic iodonium cations are preferred, and aryl sulfonium cations are more preferred. Specifically, examples include cations represented by any of the above formulas (b2-1) to (b2-4) (hereinafter, depending on the formula number, they may be referred to as "cation (b2-1)," etc.).

The structural unit represented by formula (II-2-A') is preferably the structural unit represented by formula (II-2-A).
[In formula (II-2-A),
R ^III3 , X ^III3 , and ZA ⁺ have the same meaning as above.
z represents an integer between 0 and 6.
R ^III2 and R ^III4 each independently represent a hydrogen atom, a fluorine atom, or a perfluoroalkyl group having 1 to 6 carbon atoms, and when z is 2 or greater, multiple R ^III2 and R ^III4 may be identical or different from one another.
Q ^a and Q ^b each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms.

The perfluoroalkyl groups having 1 to 6 carbon atoms represented by R ^III2 , R ^III4 , Q ^a , and Q ^b are the same as the perfluoroalkyl groups having 1 to 6 carbon atoms represented by Q ^b1 mentioned above.

The structural unit represented by formula (II-2-A) is preferably the structural unit represented by formula (II-2-A-1).
[In formula (II-2-A-1),
R ^III² , R ^III³ , R ^III⁴ , Q ^a , Q ^b , z, and ZA ⁺ have the same meaning as above.
R ^III5 represents a saturated hydrocarbon group with 1 to 12 carbon atoms.
X ^I2 represents a divalent saturated hydrocarbon group having 1 to 11 carbon atoms, and the _-CH2- contained in the saturated hydrocarbon group may be replaced with -O-, -S-, or -CO-, and the hydrogen atoms contained in the saturated hydrocarbon group may be substituted with halogen atoms or hydroxyl groups.

Examples of saturated hydrocarbon groups having 1 to 12 carbon atoms represented by R ^III5 include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups.
Examples of divalent saturated hydrocarbon groups represented by X ^I2 include those similar to the divalent saturated hydrocarbon groups represented by X ^III3 .

The structural unit represented by formula (II-2-A-2) is preferred over the structural unit represented by formula (II-2-A-1).
[In formula (II-2-A-2),
R ^III3 , R ^III5 , and ZA ⁺ have the same meaning as above.
m and n each independently represent either 1 or 2.

Examples of structural units represented by formula (II-2-A') include the following structural units, structural units in which the group corresponding to the methyl group of R ^III3 is replaced by a hydrogen atom, a halogen atom (e.g., a fluorine atom), or a C1-C6 alkyl group which may have a halogen atom (e.g., a trifluoromethyl group), and the structural unit described in International Publication No. 2012/050015. ZA ⁺ represents an organic cation.

The structural unit having a sulfonio group and an organic anion in its side chain is preferably the structural unit represented by formula (II-1-1).
[In formula (II-1-1),
A ^II1 represents a single bond or a divalent linking group.
R ^II1 represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.
R ^II2 and R ^II3 each independently represent a hydrocarbon group having 1 to 18 carbon atoms, and R ^II2 and R ^II3 may be bonded to each other to form a ring with the sulfur atom to which they are bonded.
R ^II4 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
^A- represents an organic anion.
Examples of divalent aromatic hydrocarbon groups having 6 to 18 carbon atoms represented by R ^II1 include phenylene groups and naphthylene groups.
Examples of hydrocarbon groups represented by R ^II2 and R ^II3 include alkyl groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining these.
Examples of alkyl groups and alicyclic hydrocarbon groups are the same as those described above.
Examples of aromatic hydrocarbon groups include aryl groups such as phenyl, naphthyl, anthryl, biphenyl, and phenanthryl groups.
Examples of combined groups include groups combining alkyl groups and alicyclic hydrocarbon groups as described above, aralkyl groups such as benzyl groups, aromatic hydrocarbon groups having alkyl groups (p-methylphenyl group, p-tert-butylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups having alicyclic hydrocarbon groups (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), and aryl-cycloalkyl groups such as phenylcyclohexyl groups.
Examples of halogen atoms represented by ^RII4 include fluorine, chlorine, bromine, and iodine atoms.
Examples of alkyl groups having 1 to 6 carbon atoms that may have a halogen atom represented by R ^{II 4} are the same as alkyl groups having 1 to 6 carbon atoms that may have a halogen atom represented by R ^{a 8} .
Examples of the divalent linking group represented by A ^II1 include divalent saturated hydrocarbon groups having 1 to 18 carbon atoms, and the _-CH2- contained in the divalent saturated hydrocarbon group may be replaced with -O-, -S-, or -CO-. Specifically, the same as the divalent saturated hydrocarbon groups having 1 to 18 carbon atoms represented by X ^III3 can be cited.

Examples of structural units containing the cation in formula (II-1-1) include the structural unit represented below, and structural units in which the group corresponding to the methyl group of R ^II4 is replaced by a hydrogen atom, a halogen atom (e.g., a fluorine atom), or a C1-C6 alkyl group which may have a halogen atom (e.g., a trifluoromethyl group).

Examples of organic anions represented by ^A- include sulfonic acid anions, sulfonylimide anions, sulfonylmethide anions, and carboxylic acid anions. The organic anion represented by ^A- is preferably a sulfonic acid anion, and examples of sulfonic acid anions include those similar to the anions contained in the salt represented by formula (B1) above.

Examples of sulfonylimide anions represented by ^A- include the following:

Examples of sulfonylmethide anions include the following:

Examples of carboxylic acid anions include the following:

Examples of structural units represented by formula (II-1-1) include the following structural units.

When resin (A) contains structural unit (II), the content of structural unit (II) is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, and even more preferably 3 to 10 mol%, relative to the total structural units of resin (A).

Resin (A) may contain structural units other than those described above, and examples of such structural units include those well known in the art.

The resin (A) is preferably a resin consisting of structural units (a1) and structural units (s), that is, a copolymer of monomer (a1) and monomer (s).
The structural unit (a1) is preferably at least one selected from the group consisting of structural unit (a1-0), structural unit (a1-1), and structural unit (a1-2) (preferably a structural unit having a cyclohexyl group or a cyclopentyl group), more preferably at least two, and even more preferably at least two selected from the group consisting of structural unit (a1-1) and structural unit (a1-2).
The structural unit (s) is preferably at least one selected from the group consisting of structural units (a2) and structural units (a3). The structural unit (a2) is preferably a structural unit represented by formula (a2-1) or a structural unit represented by formula (a2-A). The structural unit (a3) is preferably at least one selected from the group consisting of a structural unit represented by formula (a3-1), a structural unit represented by formula (a3-2), and a structural unit represented by formula (a3-4).

Each structural unit constituting resin (A) may be used individually or in combination of two or more types, and these structural units can be produced by known polymerization methods (e.g., radical polymerization) using monomers that derive these structural units. The content of each structural unit in resin (A) can be adjusted by the amount of monomer used in polymerization.
The weight-average molecular weight of resin (A) is preferably 2,000 or more (more preferably 2,500 or more, even more preferably 3,000 or more) and 50,000 or less (more preferably 30,000 or less, even more preferably 15,000 or less). In this specification, the weight-average molecular weight is the value obtained by gel permeation chromatography under the conditions described in the examples.

<Resins other than resin (A)>
The resist composition of the present invention may contain resins other than resin (A).
Examples of resins other than resin (A) include resins containing structural unit (a4) or structural unit (a5) (hereinafter sometimes referred to as resin (X)).

Among the resins (X), resins containing structural units (a4) are preferred.
In resin (X), the content of structural units (a4) is preferably 30 mol% or more, more preferably 40 mol% or more, and even more preferably 45 mol% or more, relative to the total amount of all structural units in resin (X).
Structural units that resin (X) may further have include structural unit (a2), structural unit (a3), and structural units derived from other known monomers. In particular, resin (X) is preferably a resin consisting only of structural unit (a4) and/or structural unit (a5), and more preferably a resin consisting only of structural unit (a4).
Each structural unit constituting the resin (X) may be used individually or in combination of two or more types, and these structural units can be produced by known polymerization methods (e.g., radical polymerization) using monomers that induce these structural units. The content of each structural unit in the resin (X) can be adjusted by the amount of monomer used in polymerization.
The weight-average molecular weight of resin (X) is preferably 6,000 or more (more preferably 7,000 or more) and 80,000 or less (more preferably 60,000 or less). The means for measuring the weight-average molecular weight of resin (X) is the same as in the case of resin (A).
If the resist composition contains resin (X), its content is preferably 1 to 60 parts by mass, more preferably 1 to 50 parts by mass, even more preferably 1 to 40 parts by mass, even more preferably 1 to 30 parts by mass, and even more preferably 1 to 8 parts by mass, per 100 parts by mass of resin (A).

The content of resin (A) in the resist composition is preferably 80% to 99% by mass, and more preferably 90% to 99% by mass, relative to the solid content of the resist composition. Furthermore, if resins other than resin (A) are included, the total content of resin (A) and the other resins is preferably 80% to 99% by mass, and more preferably 90% to 99% by mass, relative to the solid content of the resist composition. The solid content of the resist composition and the resin content thereto can be measured using known analytical means such as liquid chromatography or gas chromatography.

<Solvent (E)>
The solvent (E) content in the resist composition is usually 90% by mass or more and 99.9% by mass or less, preferably 92% by mass or more and 99% by mass or less, and more preferably 94% by mass or more and 99% by mass or less. The solvent (E) content can be measured by known analytical means such as liquid chromatography or gas chromatography.
Examples of solvent (E) include glycol ether esters such as ethyl cellosolve acetate, methyl cellosolve acetate, and propylene glycol monomethyl ether acetate; glycol ethers such as propylene glycol monomethyl ether; esters such as ethyl lactate, butyl acetate, amyl acetate, and ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone, and cyclohexanone; and cyclic esters such as γ-butyrolactone. One of solvents (E) may be used alone, or two or more may be used.

<Quencher (C)>
Quencher (C) can be a salt that generates an acid weaker in acidity than the acid generated from the acid generator (B), or a basic nitrogen-containing organic compound. The quencher (C) content is preferably about 0.01 to 15% by mass, more preferably about 0.01 to 10% by mass, even more preferably about 0.1 to 8% by mass, and even more preferably about 0.1 to 7% by mass, based on the solid content of the resist composition.

<A salt that produces an acid that is less acidic than the acid produced by the acid generator.>
The acidity of a salt that generates an acid weaker than the acid generated from the acid generator (B) is expressed by its acid dissociation constant (pKa). A salt that generates an acid weaker than the acid generated from the acid generator (B) is a salt whose acid dissociation constant is usually -3 < pKa, preferably -1 < pKa < 7, and more preferably 0 < pKa < 5.
Examples of salts that generate an acid weaker in acidity than the acid generated from the acid generator (B) include the salt represented by the following formula, the salt represented by formula (D) described in Japanese Patent Publication No. 2015-147926 (hereinafter sometimes referred to as "weak acid intramolecular salt (D)"), and the salts described in Japanese Patent Publication Nos. 2012-229206, 2012-6908, 2012-72109, 2011-39502, and 2011-191745. Preferably, the salt that generates an acid weaker in acidity than the acid generated from the acid generator (B) is a salt that generates a carboxylic acid weaker in acidity than the acid generated from the acid generator (B) (a salt having a carboxylic acid anion), more preferably a weak acid intramolecular salt (D), and even more preferably a diphenyliodonium salt containing a phenyl group substituted with a carboxylic acid anion among the weak acid intramolecular salts (D).

The weak acid intramolecular salt (D) is preferably a diphenyliodonium salt having an iodonium cation to which two phenyl groups are bonded and a carboxylic acid anion to which at least one of the two phenyl groups bonded to the iodonium cation is substituted, and examples of salts represented by the following formula include:
[In formula (D),
^RD1 and ^RD2 independently represent a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 7 carbon atoms, an acyloxy group having 2 to 7 carbon atoms, an alkoxycarbonyl group having 2 to 7 carbon atoms, a nitro group, or a halogen atom.
m' and n' each independently represent an integer between 0 and 4. If m' is 2 or greater, multiple R ^D1s may be the same or different. If n' is 2 or greater, multiple R ^D2s may be the same or different.
Examples of hydrocarbon groups in ^RD1 and ^RD2 include chain hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by combining these.
Examples of chain-type hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, and nonyl groups.
The alicyclic hydrocarbon group may be monocyclic or polycyclic, and may be saturated or unsaturated. Examples include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclononyl, and cyclododecyl groups, as well as norbonyl and adamantyl groups.
Examples of aromatic hydrocarbon groups include phenyl group, 1-naphthyl group, 2-naphthyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-propylphenyl group, 4-isopropylphenyl group, 4-butylphenyl group, 4-t-butylphenyl group, 4-hexylphenyl group, 4-cyclohexylphenyl group, anthyl group, p-adamantylphenyl group, tolyl group, xylyl group, cumenyl group, mesityl group, biphenyl group, phenanthryl group, 2,6-diethylphenyl group, 2-methyl-6-ethylphenyl group, and other aryl groups.
Groups formed by combining these include alkyl-cycloalkyl groups, cycloalkyl-alkyl groups, and aralkyl groups (for example, phenylmethyl group, 1-phenylethyl group, 2-phenylethyl group, 1-phenyl-1-propyl group, 1-phenyl-2-propyl group, 2-phenyl-2-propyl group, 3-phenyl-1-propyl group, 4-phenyl-1-butyl group, 5-phenyl-1-pentyl group, 6-phenyl-1-hexyl group, etc.).
Examples of alkoxy groups include methoxy groups and ethoxy groups.
Examples of acyl groups include acetyl groups, propanoyl groups, benzoyl groups, and cyclohexanecarbonyl groups.
Examples of acyloxy groups include groups in which an oxy group (-O-) is bonded to the above-mentioned acyl group.
Examples of alkoxycarbonyl groups include groups in which a carbonyl group (-CO-) is bonded to the above-mentioned alkoxy group.
Examples of halogen atoms include fluorine, chlorine, and bromine atoms.
^RD1 and ^RD2 are each preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl group having 2 to 4 carbon atoms, an acyloxy group having 2 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group, or a halogen atom.
m' and n' are each independently preferably integers from 0 to 2, and more preferably 0. If m' is 2 or greater, multiple R ^D1s may be the same or different, and if n' is 2 or greater, multiple R ^D2s may be the same or different.
More specifically, the following salts are examples:

Basic nitrogen-containing organic compounds include amines and ammonium salts. Amines include aliphatic amines and aromatic amines. Aliphatic amines include primary amines, secondary amines, and tertiary amines.
Examples of amines include 1-naphthylamine, 2-naphthylamine, aniline, diisopropylaniline, 2-,3- or 4-methylaniline, 4-nitroaniline, N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, tripropylamine, and tributylamine. Amine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine, methyldinonylamine, methylddecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethylddecylamine Mine, dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4'-diamino-1,2-diphenylethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 2,2'-methylenebisaniline, imidazole, 4-methylimidazole, pyridine, 4-methylpyridine, 1,2-di(2-pyridyl)ethanol Examples include 1,2-di(4-pyridyl)ethane, 1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene, 1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane, di(2-pyridyl)ketone, 4,4'-dipyridyl sulfide, 4,4'-dipyridyl disulfide, 2,2'-dipyridylamine, 2,2'-dipicolylamine, bipyridine, and the like. Preferably, aromatic amines such as diisopropylaniline are included, and more preferably, 2,6-diisopropylaniline is included.
Examples of ammonium salts include tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide, 3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylammonium salicylate, and choline.

<Other ingredients>
The resist composition of the present invention may optionally contain components other than those described above (hereinafter sometimes referred to as "other components (F)"). There are no particular limitations on other components (F), and additives known in the resist field, such as sensitizers, dissolution inhibitors, surfactants, stabilizers, dyes, etc., can be used.

<Preparation of resist composition>
The resist composition of the present invention can be prepared by mixing a salt (I) and a resin (A), and optionally an acid generator (B), a resin other than resin (A), a solvent (E), a quencher (C), and other components (F). The mixing order is arbitrary and not particularly limited. The mixing temperature can be selected from 10 to 40°C, depending on the type of resin, etc., and the solubility of the resin, etc., in the solvent (E). The mixing time can be selected from 0.5 to 24 hours, depending on the mixing temperature. There are no particular restrictions on the mixing method, and stirring or other methods can be used.
After mixing the components, it is preferable to filter the mixture using a filter with a pore size of approximately 0.003 to 0.2 μm.

<Method for manufacturing resist patterns>
The method for manufacturing a resist pattern of the present invention is:
(1) A step of applying the resist composition of the present invention onto a substrate,
(2) A step of drying the coated composition to form a composition layer,
(3) Exposure step of the composition layer,
(4) A step of heating the composition layer after exposure, and (5) A step of developing the composition layer after heating.
The resist composition can be applied to a substrate using commonly used equipment such as a spin coater. Examples of substrates include inorganic substrates such as silicon wafers, and organic substrates with a resist film formed on their surface. Before applying the resist composition, the substrate may be cleaned, or an anti-reflective film may be formed on the substrate.
The solvent is removed and a composition layer is formed by drying the coated composition. Drying is performed, for example, by evaporating the solvent using a heating device such as a hot plate (so-called pre-baking), or by using a vacuum device. The heating temperature is preferably 50 to 200°C, and the heating time is preferably 10 to 180 seconds. Furthermore, the pressure during vacuum drying is preferably about 1 to 1.0 × ^10⁵ Pa.
The resulting composition layer is typically exposed using an exposure machine. The exposure machine may be an immersion exposure machine. Various types of exposure light sources can be used, including those that emit ultraviolet laser light such as KrF excimer lasers (wavelength 248 nm), ArF excimer lasers (wavelength 193 nm), and _F2 excimer lasers (wavelength 157 nm); those that emit far-ultraviolet or vacuum-ultraviolet harmonic laser light by wavelength conversion of laser light from a solid-state laser light source (such as a YAG or semiconductor laser); electron beams; and those that irradiate with ultra-ultraviolet (EUV) light. In this specification, the irradiation of these radiations is sometimes collectively referred to as "exposure." During exposure, exposure is usually performed through a mask corresponding to the desired pattern. If the exposure light source is an electron beam, exposure may be performed by direct drawing without using a mask.
The composition layer after exposure is subjected to heat treatment (so-called post-exposure bake) to promote the deprotection reaction at acid-unstable groups. The heating temperature is usually around 50 to 200°C, preferably around 70 to 150°C. Chemical treatment (silylation) may be performed to adjust the hydrophilicity or hydrophobicity of the resin on the surface side of the composition after heating. Alternatively, before development, the process of coating the resist composition, drying, exposure, and heating may be repeated on the composition layer after exposure.
The heated composition layer is typically developed using a developing device and a developing solution. Development methods include the dip method, paddle method, spray method, and dynamic dispensing method. The development temperature is preferably, for example, 5 to 60°C, and the development time is preferably, for example, 5 to 300 seconds. By selecting the type of developing solution as described below, a positive-type resist pattern or a negative-type resist pattern can be manufactured.
When producing a positive resist pattern from the resist composition of the present invention, an alkaline developer is used as the developer. The alkaline developer can be any alkaline aqueous solution used in this field. For example, aqueous solutions of tetramethylammonium hydroxide or (2-hydroxyethyl)trimethylammonium hydroxide (commonly known as choline) can be used. The alkaline developer may also contain a surfactant.
It is preferable to wash the resist pattern with ultrapure water after development, and then remove any remaining water on the substrate and pattern.
When manufacturing a negative-type resist pattern from the resist composition of the present invention, a developer containing an organic solvent (hereinafter sometimes referred to as "organic developer") is used as the developer.
Examples of organic solvents contained in organic developers include ketone solvents such as 2-hexanone and 2-heptanone; glycol ether ester solvents such as propylene glycol monomethyl ether acetate; ester solvents such as butyl acetate; glycol ether solvents such as propylene glycol monomethyl ether; amide solvents such as N,N-dimethylacetamide; and aromatic hydrocarbon solvents such as anisole.
In the organic developer, the content of the organic solvent is preferably 90% by mass or more and 100% by mass or less, more preferably 95% by mass or more and 100% by mass or less, and even more preferably substantially composed of only organic solvents.
Among these, organic developers containing butyl acetate and/or 2-heptanone are preferred. The total content of butyl acetate and 2-heptanone in the organic developer is preferably 50% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably substantially only butyl acetate and/or 2-heptanone.
Organic developers may contain surfactants. Furthermore, organic developers may contain trace amounts of water.
During development, the development process may be stopped by substituting a different type of solvent for the organic developer.
It is preferable to wash the developed resist pattern with a rinsing solution. The rinsing solution is not particularly limited as long as it does not dissolve the resist pattern, and a solution containing a general organic solvent can be used, preferably an alcohol solvent or an ester solvent.
After cleaning, it is preferable to remove any remaining rinse solution from the substrate and patterns.

<Application>
The resist composition of the present invention is suitable as a resist composition for KrF excimer laser exposure, an ArF excimer laser exposure, an electron beam (EB) exposure, or an EUV exposure, and is particularly suitable as a resist composition for electron beam (EB) exposure or an EUV exposure, and is useful for semiconductor microfabrication.

The present invention will be described in more detail with reference to examples. In the examples, "%" and "parts" representing the content or amount used are based on mass unless otherwise specified.
The weight-average molecular weight was determined by gel permulation chromatography. The analytical conditions for gel permulation chromatography are as follows:
Column: TSKgel Multipore HXL-M x 3 + guard column (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min
Detector: RI detector; Column temperature: 40°C
Injection volume: 100μl
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)
The structure of the compound was confirmed by measuring the molecular ion peak using mass spectrometry (LC: Agilent 1100, MASS: Agilent LC/MSD). In the following examples, the value of this molecular ion peak is indicated as "MASS".

Example 1: Synthesis of the salt represented by formula (I-1)
2.48 parts of the compound represented by formula (I-1-a) and 40 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 1.62 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 7.01 parts of the salt represented by formula (I-1-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 20 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing procedure was repeated five times. The obtained organic layer was concentrated, and 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, after which the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 8.19 parts of the salt represented by formula (I-1).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 667.0

Example 2: Synthesis of the salt represented by formula (I-3)
5.00 parts of the compound represented by formula (I-3-a) and 40 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 1.62 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 7.01 parts of the salt represented by formula (I-1-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, then cooled to 23°C. 20 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing procedure was repeated five times. The obtained organic layer was concentrated, and 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, after which the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 10.22 parts of the salt represented by formula (I-3).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI(-)Spectrum): M ^- 918.8

Example 3: Synthesis of the salt represented by formula (I-6)
5.00 parts of the compound represented by formula (I-3-a) and 40 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 1.62 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 6.95 parts of the salt represented by formula (I-6-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 20 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. The obtained organic layer was concentrated, and 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, after which the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 9.99 parts of the salt represented by formula (I-6).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI(-)Spectrum): M ^- 912.8

Example 4: Synthesis of the salt represented by formula (I-11)
2.48 parts of the compound represented by formula (I-1-a) and 40 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 1.62 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 7.45 parts of the salt represented by formula (I-11-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, then cooled to 23°C. 20 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing procedure was repeated five times. The obtained organic layer was concentrated, and 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, after which the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 7.92 parts of the salt represented by formula (I-11).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI(-)Spectrum): M ^- 711.0

Example 5: Synthesis of the salt represented by formula (I-26)
0.50 parts of the compound represented by formula (I-3-a) and 20 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 0.16 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 0.78 parts of the salt represented by formula (I-26-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 10 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 10 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. After concentrating the obtained organic layer, 20 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 0.91 parts of the salt represented by formula (I-26).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI (-) Spectrum): M ^- 1000.8

Example 6: Synthesis of the salt represented by formula (I-28)
0.47 parts of the compound represented by formula (I-28-a) and 20 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 0.16 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 0.78 parts of the salt represented by formula (I-26-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 10 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 10 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. After concentrating the obtained organic layer, 20 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 0.65 parts of the salt represented by formula (I-28).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI(-)Spectrum): M ^- 1016.8

Example 7: Synthesis of the salt represented by formula (I-134)
0.50 parts of the compound represented by formula (I-3-a) and 20 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 0.16 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 0.70 parts of the salt represented by formula (I-134-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 10 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 10 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. After concentrating the obtained organic layer, 20 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 0.91 parts of the salt represented by formula (I-134).
MS (ESI (+) Spectrum): M ⁺ 261.1
MS (ESI (-) Spectrum): M ^- 1000.8

Example 8: Synthesis of the salt represented by formula (I-460)
0.47 parts of the compound represented by formula (I-28-a) and 20 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 0.16 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 0.91 parts of the salt represented by formula (I-460-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 10 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 10 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. After concentrating the obtained organic layer, 20 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 0.79 parts of the salt represented by formula (I-460).
MS (ESI (+) Spectrum): M ⁺ 393.1
MS (ESI(-)Spectrum): M ^- 1016.8

Example 9: Synthesis of the salt represented by formula (I-610)
1.28 parts of the salt represented by formula (I-610-c) and 30 parts of dimethylformamide were mixed and stirred at 23°C for 30 minutes. Then, 0.08 parts of potassium carbonate and 0.03 parts of potassium iodide were added, and the temperature was raised to 75°C. 0.40 parts of the compound represented by formula (I-610-a) were added to the resulting mixture and stirred at 75°C for 5 hours, then cooled to 23°C. 50 parts of chloroform and 20 parts of 5% aqueous oxalic acid were added to the resulting mixture and stirred at 23°C for 30 minutes. The organic layer was then separated by liquid-liquid extraction. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes. The organic layer was then separated by liquid-liquid extraction. This washing procedure was repeated five times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 1.34 parts of the salt represented by formula (I-610).
MS (ESI (+) Spectrum): M ⁺ 525.0
MS (ESI(-)Spectrum): M ^- 691.0

Example 10: Synthesis of the salt represented by formula (I-36)
0.16 parts of the compound represented by formula (I-36-a) and 20 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 0.16 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 0.70 parts of the salt represented by formula (I-1-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 20 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 0.35 parts of the salt represented by formula (I-36).
MS (ESI (+) Spectrum): M ⁺ 263.1
MS (ESI(-)Spectrum): M ^- 621.0

Example 11: Synthesis of the salt represented by formula (I-954)
1.28 parts of the salt represented by formula (I-610-c) and 30 parts of dimethylformamide were mixed and stirred at 23°C for 30 minutes. Then, 0.08 parts of potassium carbonate and 0.03 parts of potassium iodide were added, and the temperature was raised to 75°C. 0.59 parts of the compound represented by formula (I-954-a) were added to the resulting mixture and stirred at 75°C for 5 hours, then cooled to 23°C. 50 parts of chloroform and 20 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes. The organic layer was then separated by liquid-liquid extraction. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes. The organic layer was then separated by liquid-liquid extraction. This washing procedure was repeated five times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 1.46 parts of the salt represented by formula (I-954).
MS (ESI (+) Spectrum): M ⁺ 525.0
MS (ESI (-) Spectrum): M ^- 832.9

Example 12: Synthesis of the salt represented by formula (I-958)
1.28 parts of the salt represented by formula (I-610-c) and 30 parts of dimethylformamide were mixed and stirred at 23°C for 30 minutes. Then, 0.08 parts of potassium carbonate and 0.03 parts of potassium iodide were added, and the temperature was raised to 75°C. 0.61 parts of the compound represented by formula (I-958-a) were added to the resulting mixture and stirred at 75°C for 5 hours, then cooled to 23°C. 50 parts of chloroform and 20 parts of 5% aqueous oxalic acid were added to the resulting mixture and stirred at 23°C for 30 minutes. The organic layer was then separated by liquid-liquid extraction. 20 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes. The organic layer was then separated by liquid-liquid extraction. This washing procedure was repeated five times. After concentrating the obtained organic layer, 30 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 1.53 parts of the salt represented by formula (I-958).
MS (ESI (+) Spectrum): M ⁺ 525.0
MS (ESI (-) Spectrum): M ^- 846.9

Example 13: Synthesis of the salt represented by formula (I-956)
0.36 parts of the compound represented by formula (I-956-a) and 20 parts of chloroform were mixed and stirred at 23°C for 30 minutes. 0.16 parts of the compound represented by formula (I-1-b) were added to the resulting mixed solution and stirred at 50°C for 2 hours. 0.96 parts of the salt represented by formula (I-610-c) were added to the resulting mixed solution and stirred at 50°C for 3 hours, after which it was cooled to 23°C. 10 parts of 5% aqueous oxalic acid solution were added to the resulting mixture and stirred at 23°C for 30 minutes, after which the organic layer was separated. 10 parts of deionized water were added to the obtained organic layer and stirred at 23°C for 30 minutes, after which the organic layer was separated. This washing operation was repeated five times. After concentrating the obtained organic layer, 20 parts of tert-butyl methyl ether were added to the concentrated residue and stirred, and the supernatant was removed. The obtained residue was dissolved in acetonitrile and concentrated to obtain 1.01 parts of the salt represented by formula (I-956).
MS (ESI (+) Spectrum): M ⁺ 525.0
MS (ESI(-)Spectrum): M ^- 818.9

Resin Synthesis The compounds (monomers) used in the synthesis of resin (A) are shown below. Hereafter, these compounds will be referred to as "monomer (a1-1-3)" etc., according to their formula numbers.

Synthesis Example 1 [Synthesis of Resin A1]
Monomers (a1-4-2), (a1-1-3), and (a1-2-6) were used as monomers, and they were mixed in a molar ratio [monomer (a1-4-2): monomer (a1-1-3): monomer (a1-2-6)] of 38:24:38. Further, methyl isobutyl ketone was added to this monomer mixture in an amount of 1.5 times the total mass of all monomers. To the resulting mixture, azobisisobutyronitrile was added as an initiator in an amount of 7 mol% of the total number of moles of all monomers, and polymerization was carried out by heating at 85°C for about 5 hours. Subsequently, an aqueous solution of p-toluenesulfonic acid (2.5 wt%) in an amount of 2.0 times the total mass of all monomers was added to the polymerization reaction solution, and after stirring for 6 hours, the solution was separated. The resulting organic layer was poured into a large amount of n-heptane to precipitate the resin, which was then filtered and recovered to obtain resin A1 (polymer) with a weight-average molecular weight of approximately 5.3 × ^10³ in yield of 78%. This resin A1 has the following structural units.

Synthesis Example 2 [Synthesis of Resin A2]
Monomers (a1-4-2) and (a1-2-6) were used as monomers, and they were mixed in a molar ratio [monomer (a1-4-2):monomer (a1-2-6)] of 38:62. Furthermore, methyl isobutyl ketone was added to this monomer mixture in an amount of 1.5 times the total mass of all monomers. Azobisisobutyronitrile was added to the resulting mixture as an initiator at a concentration of 7 mol% relative to the total moles of all monomers, and polymerization was carried out by heating at 85°C for approximately 5 hours. Subsequently, 2.0 times the mass of p-toluenesulfonic acid aqueous solution (2.5 wt%) relative to the total mass of all monomers was added to the polymerization reaction solution, stirred for 6 hours, and then separated. The resulting organic layer was poured into a large amount of n-heptane to precipitate the resin, which was then filtered and recovered to obtain resin A2 (polymer) with a weight-average molecular weight of approximately 5.4 × ^10³ in yield of 89%. This resin A2 has the following structural units.

Synthesis Example 3 [Synthesis of Resin A3]
Monomers (a1-1-3), (a1-2-6), (a2-1-3), (a3-4-2), and (a1-4-2) were used as monomers, and they were mixed in a molar ratio [monomer (a1-1-3): monomer (a1-2-6): monomer (a2-1-3): monomer (a3-4-2): monomer (a1-4-2)] of 20:35:3:15:27. Furthermore, methyl isobutyl ketone was added to this monomer mixture in an amount equal to 1.5 times the total mass of all monomers. To the resulting mixture, azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were added as initiators at concentrations of 1.2 mol% and 3.6 mol%, respectively, relative to the total amount of monomers, and these mixtures were heated at 73°C for approximately 5 hours. Subsequently, 2.5% by weight of p-toluenesulfonic acid aqueous solution was added to the polymerization reaction solution in an amount equal to 2.0 times the total mass of all monomers, and after stirring for 12 hours, the mixture was separated. The recovered organic layer was poured into a large amount of n-heptane to precipitate the resin, which was then filtered and recovered to obtain resin A3 with a weight-average molecular weight of approximately 5.3 × ^10³ in yield of 63%. This resin A3 has the following structural units.

Synthesis Example 4 [Synthesis of Resin A4]
Monomers (a1-1-3), (a1-2-6), (a2-1-3), (a3-4-2), and (a1-4-13) were used as monomers, and they were mixed in a molar ratio [monomer (a1-1-3): monomer (a1-2-6): monomer (a2-1-3): monomer (a3-4-2): monomer (a1-4-13)] of 20:35:3:15:27. Furthermore, methyl isobutyl ketone was added to this monomer mixture in an amount equal to 1.5 times the total mass of all monomers. To the resulting mixture, azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were added as initiators at concentrations of 1.2 mol% and 3.6 mol%, respectively, relative to the total amount of monomers, and these mixtures were heated at 73°C for approximately 5 hours. Subsequently, 2.5% by weight of p-toluenesulfonic acid aqueous solution was added to the polymerization reaction solution in an amount equal to 2.0 times the total mass of all monomers, and after stirring for 12 hours, the mixture was separated. The recovered organic layer was poured into a large amount of n-heptane to precipitate the resin, which was then filtered and recovered to obtain resin A4 with a weight-average molecular weight of approximately 5.1 × ^10³ in yield of 61%. This resin A4 has the following structural units.

<Preparation of the resist composition>
As shown in Table 2, the following components were mixed, and the resulting mixture was filtered through a fluororesin filter with a pore size of 0.2 μm to prepare a resist composition.

<Resin>
A1 to A4: Resin A1 to Resin A4
<Salt (I)>
I-1: Salt represented by formula (I-1) I-3: Salt represented by formula (I-3) I-6: Salt represented by formula (I-6) I-11: Salt represented by formula (I-11) I-26: Salt represented by formula (I-26) I-28: Salt represented by formula (I-28) I-36: Salt represented by formula (I-36) I-134: Salt represented by formula (I-134) I-460: Salt represented by formula (I-460) I-610: Salt represented by formula (I-610) I-954: Salt represented by formula (I-954) I-956: Salt represented by formula (I-956) I-958: Salt represented by formula (I-958) <Acid Generator>
IX-1
IX-2
IX-3
IX-4
<Quencher (C)>
C1: Synthesized by the method described in Japanese Patent Publication No. 2011-39502
<Solvent>
Propylene glycol monomethyl ether acetate 400 parts Propylene glycol monomethyl ether 100 parts γ-butyrolactone 5 parts

(Evaluation of resist compositions by electron beam exposure)
A 6-inch silicon wafer was treated on a direct hot plate with hexamethyldisilazane at 90°C for 60 seconds. A resist composition was spin-coated onto this silicon wafer to a thickness of 0.04 μm. Subsequently, the composition layer was formed by pre-baking on a direct hot plate at the temperature shown in the "PB" column of Table 2 for 60 seconds. Contact hole patterns (hole pitch 40 nm / hole diameter 17 nm) were directly drawn onto the composition layer formed on the wafer using an electron beam lithography machine [ELS-F125 125 keV manufactured by Elionix Co., Ltd.] by gradually changing the exposure amount.
After exposure, post-exposure baking was performed on a hot plate at the temperature shown in the "PEB" column of Table 2 for 60 seconds, and then paddle development was performed with a 2.38% by mass tetramethylammonium hydroxide aqueous solution for 60 seconds to obtain the resist pattern.

The effective sensitivity was defined as the exposure level at which the hole diameter formed in the resist pattern obtained after development was 17 nm.

<CD Uniformity (CDU) Evaluation>
For effective sensitivity, the hole diameter of a pattern formed with a hole diameter of 17 nm was measured 24 times for each hole, and the average value was taken as the average hole diameter for that hole. The standard deviation was calculated from a population of 400 measurements of the average hole diameter of a pattern formed with a hole diameter of 17 nm on the same wafer.
The results are shown in Table 3. The values in the table indicate the standard deviation (nm).

Compared to comparative compositions 1-4, compositions 1-11 and 23-25 showed smaller standard deviations and better CD uniformity (CDU) evaluation.

(Evaluation of resist compositions by electron beam exposure)
A 6-inch silicon wafer was treated on a direct hot plate with hexamethyldisilazane at 90°C for 60 seconds. A resist composition was spin-coated onto this silicon wafer to a thickness of 0.04 μm. Subsequently, the composition layer was formed by pre-baking on a direct hot plate at the temperature shown in the "PB" column of Table 2 for 60 seconds. Contact hole patterns (hole pitch 40 nm / hole diameter 17 nm) were directly drawn onto the composition layer formed on the wafer using an electron beam lithography machine [ELS-F125 125 keV manufactured by Elionix Co., Ltd.] by gradually changing the exposure amount.
After exposure, post-exposure baking was performed on a hot plate at the temperature shown in the "PEB" column of Table 2 for 60 seconds. Next, the composition layer on this silicon wafer was developed using butyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) as the developer by dynamic dispensing at 23°C for 20 seconds to obtain a resist pattern.

The effective sensitivity was defined as the exposure level at which the hole diameter formed in the resist pattern obtained after development was 17 nm.

<CD Uniformity (CDU) Evaluation>
For effective sensitivity, the hole diameter of a pattern formed with a hole diameter of 17 nm was measured 24 times for each hole, and the average value was taken as the average hole diameter for that hole. The standard deviation was calculated from a population of 400 measurements of the average hole diameter of a pattern formed with a hole diameter of 17 nm on the same wafer.
The results are shown in Table 4. The values in the table indicate the standard deviation (nm).

Compared to comparative compositions 5-8, compositions 12-22 and 26-28 showed smaller standard deviations and better CD uniformity (CDU) evaluation.

The resist composition containing the salt of the present invention exhibits good CD uniformity (CDU) and is useful for semiconductor microfabrication.

Claims (15)

An acid generator containing a salt represented by formula (I).
[In formula (I),
^Q1 and ^Q2 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
^R11 and ^R12 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
z represents an integer from 0 to 6, and when z is 2 or greater, multiple ^R11 and ^R12 may be the same or different from each other.
^X1 represents *-CO-O-, *-O-CO-, *-O-CO-O-, or *-O-, where * represents a binding site with C( ^R11 )( ^R12 ) or C( ^Q1 )( ^Q2 ).
^L1 represents a hydrocarbon group having 1 to 60 carbon atoms, which may have a single bond or substituents, and the _-CH2- contained in the hydrocarbon group may be replaced with -O-, -S-, -SO2-, or _-CO- .
X ^a and X ^b each independently represent -O- or -S-.
Ring W1 represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
Ring W represents a cyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
^R1 and ^R2 each independently represent a halogen atom, a hydroxyl group, a C1-C12 haloalkyl group, or a C1-C12 alkyl group, and the _-CH2- contained in the haloalkyl group and the alkyl group may be replaced with -O- or -CO-.
R ³ represents *-O-R ¹⁰ , *-O-CO-R ¹⁰ , *-CO-O-R ¹⁰ , *-O-CO-O-R ¹⁰ , *-O-L ¹⁰ -CO-O-R ¹⁰ , or *-O-L ¹⁰ -O-CO-R ¹⁰ , where * represents the bonding site with ring W.
^L10 represents an alkanediyl group with 1 to 6 carbon atoms.
R ¹⁰ represents a C1-C36 hydrocarbon group having an iodine atom or a C1-C12 iodate alkyl group, or a C3-C36 cyclic hydrocarbon group having a fluorine atom or a C1-C12 fluoride alkyl group, wherein the hydrocarbon group and the cyclic hydrocarbon group may have substituents, and the _-CH2- contained in the hydrocarbon group and the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
m1 represents an integer between 0 and 6, and when m1 is 2 or greater, multiple ^R1s may be the same or different from each other.
m² represents an integer between 0 and 6, and when m² is 2 or greater, multiple ^R² values may be the same or different from each other.
m3 represents an integer from 1 to 6, and when m3 is 2 or greater, multiple ^R3s may be the same or different from each other.
Z ⁺ represents an organic cation. ^L1 is a single bond, * ^-L2- or * ^-L2 - ^{X3- L3-} ( ^L2 represents a chain hydrocarbon group having 1 to 10 carbon atoms which may have substituents, a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, or a group formed by a combination of a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents and a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. * represents the bonding site with ^X1 . ^X3 represents **-CO-O-, **-O-CO-, **-O-CO-O- or **-O-, and ** represents the bonding site with ^L2 . The acid generator according to claim 1, wherein ³ represents a chain hydrocarbon group having 1 to 8 carbon atoms, which may have single bonds or substituents, and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. The acid generator according to claim 1, wherein ring W1 is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), or a group derived from a ring represented by formula (w1-15).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), and (w1-15),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position. The acid generator according to claim 1, wherein ring W is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), a group derived from a ring represented by formula (w1-12), a group derived from a ring represented by formula (w1-22), a group derived from a ring represented by formula (w1-23), or a group derived from a ring represented by formula (w1-24).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), (w1-12), (w1-22), (w1-23), and (w1-24),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position. The acid generator according to claim 1, wherein R ¹⁰ is a chain hydrocarbon group having 1 to 6 carbon atoms having an iodine atom, a group combining a cycloaliphatic hydrocarbon group having 3 to 12 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a group combining an aromatic hydrocarbon group having 6 to 14 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a cycloaliphatic hydrocarbon group having 3 to 12 carbon atoms having a fluorine atom, an iodine atom, or a trifluoromethyl group, or an aromatic hydrocarbon group having 6 to 14 carbon atoms having a fluorine atom, an iodine atom, or a trifluoromethyl group (the chain hydrocarbon group, the cycloaliphatic hydrocarbon group and the aromatic hydrocarbon group may have substituents, and the _-CH2- contained in the chain hydrocarbon group and the cycloaliphatic hydrocarbon group may be replaced with -O-, _-S- , -CO-, or -SO2-). A resist composition containing an acid generator according to any one of claims 1 to 5 and a resin having an acid-unstable group. The resist composition according to claim 6, wherein the resin having an acid-unstable group comprises at least one selected from the group consisting of a structural unit represented by formula (a1-0), a structural unit represented by formula (a1-1), and a structural unit represented by formula (a1-2).
[In formulas (a1-0), (a1-1), and (a1-2),
L ^a01 , L ^a1 , and L ^a2 each independently represent -O- or *-O-(CH ₂ ) _k1 -CO-O-, where k1 is an integer from 1 to 7, and * represents the bond site with -CO-.
^Ra01 , ^Ra4 , and ^Ra5 each independently represent a hydrogen atom, a halogen atom, or a C1-C6 alkyl group which may contain a halogen atom.
R ^a02 , R ^a03 , and R ^a04 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a combination thereof.
^Ra6 and ^Ra7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or a group formed by a combination of these.
m1 represents an integer between 0 and 14.
n1 represents an integer between 0 and 10.
n1' represents an integer between 0 and 3. The resist composition according to claim 6, wherein the resin having an acid-unstable group comprises a structural unit represented by formula (a2-A).
[In formula (a2-A),
R ^a50 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms that may contain a halogen atom.
R ^a51 represents a halogen atom, a hydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C12 alkoxyalkyl group, a C2-C12 alkoxyalkoxy group, a C2-C4 alkylcarbonyl group, a C2-C4 alkylcarbonyloxy group, an acryloyloxy group, or a methacryloyloxy group.
A ^a50 represents a single bond or ^* -X ^a51 - (A ^a52 -X ^a52 ) _nb -, where * represents the bonding site with the carbon atom to which -R ^a50 is bonded.
A ^a52 represents an alkanediyl group with 1 to 6 carbon atoms.
X ^a51 and X ^a52 independently represent -O-, -CO-O-, or -O-CO-, respectively.
nb represents either 0 or 1.
mb represents an integer between 0 and 4. If mb is an integer greater than or equal to 2, multiple R ^a51s may be identical or different from each other. The resist composition according to claim 6, further containing a salt that generates an acid with a lower acidity than the acid generated by the acid generator. (1) A step of applying the resist composition according to claim 6 onto a substrate,
(2) A step of drying the coated composition to form a composition layer,
(3) Exposure step of the composition layer,
(4) A step of heating the composition layer after exposure, and (5) A step of developing the composition layer after heating.
A method for manufacturing a resist pattern that includes [the specified element]. A salt represented by formula (I).
[In formula (I),
^Q1 and ^Q2 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
^R11 and ^R12 each independently represent a hydrogen atom, a fluorine atom, a C1-C6 alkyl group, or a C1-C6 perfluoroalkyl group.
z represents an integer from 0 to 6, and when z is 2 or greater, multiple ^R11 and ^R12 may be the same or different from each other.
^X1 represents *-CO-O-, *-O-CO-, *-O-CO-O-, or *-O-, where * represents a binding site with C( ^R11 )( ^R12 ) or C( ^Q1 )( ^Q2 ).
^L1 represents a hydrocarbon group having 1 to 60 carbon atoms, which may have a single bond or substituents, and the _-CH2- contained in the hydrocarbon group may be replaced with -O-, -S-, -SO2-, or _-CO- .
X ^a and X ^b each independently represent -O- or -S-.
Ring W1 represents an alicyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the alicyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
Ring W represents a cyclic hydrocarbon group having 3 to 36 carbon atoms, which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
^R1 and ^R2 each independently represent a halogen atom, a hydroxyl group, a C1-C12 haloalkyl group, or a C1-C12 alkyl group, and the _-CH2- contained in the haloalkyl group and the alkyl group may be replaced with -O- or -CO-.
R ³ represents *-O-R ¹⁰ , *-O-CO-R ¹⁰ , *-CO-O-R ¹⁰ , *-O-CO-O-R ¹⁰ , *-O-L ¹⁰ -CO-O-R ¹⁰ , or *-O-L ¹⁰ -O-CO-R ¹⁰ , where * represents the bonding site with ring W.
^L10 represents an alkanediyl group with 1 to 6 carbon atoms.
R ¹⁰ represents a C1-C36 hydrocarbon group having an iodine atom or a C1-C12 iodate alkyl group, or a C3-C36 cyclic hydrocarbon group having a fluorine atom or a C1-C12 fluoride alkyl group, wherein the hydrocarbon group and the cyclic hydrocarbon group may have substituents, and the _-CH2- contained in the hydrocarbon group and the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- .
m1 represents an integer between 0 and 6, and when m1 is 2 or greater, multiple ^R1s may be the same or different from each other.
m² represents an integer between 0 and 6, and when m² is 2 or greater, multiple ^R² values may be the same or different from each other.
m3 represents an integer from 1 to 6, and when m3 is 2 or greater, multiple ^R3s may be the same or different from each other.
Z ⁺ represents an organic cation. ^L1 is a single bond, * ^-L2- or * ^-L2 - ^{X3- L3-} ( ^L2 represents a chain hydrocarbon group having 1 to 10 carbon atoms which may have substituents, a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents, or a group formed by a combination of a cyclic hydrocarbon group having 3 to 24 carbon atoms which may have substituents and a chain hydrocarbon group having 1 to 8 carbon atoms which may have substituents, and the _-CH2- contained in the cyclic hydrocarbon group may be replaced with -O-, -S-, -CO- or _-SO2- , and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. * represents the bonding site with ^X1 . ^X3 represents **-CO-O-, **-O-CO-, **-O-CO-O- or **-O-, and ** represents the bonding site with ^L2 . The salt according to claim 11, wherein ³ represents a chain hydrocarbon group having 1 to 8 carbon atoms, which may have single bonds or substituents, and the _-CH2- contained in the chain hydrocarbon group may be replaced with -O- or -CO-. The salt according to claim 11 or 12, wherein ring W1 is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), or a group derived from a ring represented by formula (w1-15).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), and (w1-15),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position. The salt according to claim 11 or 12, wherein ring W is a group derived from a ring represented by formula (w1-1), a group derived from a ring represented by formula (w1-2), a group derived from a ring represented by formula (w1-3), a group derived from a ring represented by formula (w1-6), a group derived from a ring represented by formula (w1-12), a group derived from a ring represented by formula (w1-22), a group derived from a ring represented by formula (w1-23), or a group derived from a ring represented by formula (w1-24).
[In formulas (w1-1), (w1-2), (w1-3), (w1-6), (w1-12), (w1-22), (w1-23), and (w1-24),
The _-CH₂- contained in the group may be replaced with -O-, -S-, -CO-, or _-SO₂- . The bonding site is at any position. The salt according to claim 11 or 12, wherein R ¹⁰ is a chain hydrocarbon group having 1 to 6 carbon atoms having an iodine atom, a group combining a cycloaliphatic hydrocarbon group having 3 to 12 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a group combining an aromatic hydrocarbon group having 6 to 14 carbon atoms having an iodine atom and a chain hydrocarbon group having 1 to 6 carbon atoms, a cycloaliphatic hydrocarbon group having a fluorine atom, an iodine atom, or a trifluoromethyl group, or an aromatic hydrocarbon group having 6 to 14 carbon atoms having a fluorine atom, an iodine atom, or a trifluoromethyl group (the chain hydrocarbon group, the cycloaliphatic hydrocarbon group, and the aromatic hydrocarbon group may have substituents, and the _-CH2- contained in the chain hydrocarbon group and the cycloaliphatic hydrocarbon group may be replaced with -O-, -S-, -CO-, or _-SO2- ).