JP7618722B2 - Resist Composition - Google Patents

Description

The present invention relates to a salt.

特許文献２には、下記式で表されるクエンチャーを含有するレジスト組成物が記載され
ている。

Patent Document 1 describes a resist composition containing a quencher represented by the following formula:

Patent Document 2 describes a resist composition containing a quencher represented by the following formula:

JP 2011-154160 A JP 2016-006495 A

An object of the present invention is to provide a resist composition that enables the production of a resist pattern with better line edge roughness (LER) than a resist pattern formed from the above resist composition.

［式（ａ１－１）及び式（ａ１－２）中、
Ｌ^ａ１及びＬ^ａ２は、それぞれ独立に、－Ｏ－又は＊－Ｏ－（ＣＨ_２）_ｋ１－ＣＯ－Ｏ
－を表し、ｋ１は１～７のいずれかの整数を表し、＊は－ＣＯ－との結合手を表す。
Ｒ^ａ４及びＲ^ａ５は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^ａ６及びＲ^ａ７は、それぞれ独立に、炭素数１～８のアルキル基、炭素数３～１８の
脂環式炭化水素基又はこれらを組合せた基を表す。
ｍ１は、０～１４のいずれかの整数を表す。
ｎ１は、０～１０のいずれかの整数を表す。
ｎ１’は、０～３のいずれかの整数を表す。］

［式（ａ２－Ａ）中、
Ｒ^a50は、水素原子、ハロゲン原子又はハロゲン原子を有してもよい炭素数１～６のア
ルキル基を表す。
Ｒ^a51は、ハロゲン原子、ヒドロキシ基、炭素数１～６のアルキル基、炭素数１～６の
アルコキシ基、炭素数２～４のアルキルカルボニル基、炭素数２～４のアルキルカルボニ
ルオキシ基、アクリロイルオキシ基又はメタクリロイルオキシ基を表す。
Ａ^a50は、単結合又は^＊－Ｘ^a51－（Ａ^a52－Ｘ^a52）_na－を表し、＊は－Ｒ^a50が結合す
る炭素原子との結合手を表す。
Ａ^a52は、炭素数１～６のアルカンジイル基を表す。
Ｘ^a51及びＸ^a52は、それぞれ独立に、－Ｏ－、－ＣＯ－Ｏ－又は－Ｏ－ＣＯ－を表す。
ｎａは、０又は１を表す。
ｍｂは０～４のいずれかの整数を表す。ｍｂが２以上のいずれかの整数である場合、複
数のＲ^a51は互いに同一であっても異なってもよい。］

［式（Ｉ）中、
Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、それぞれ独立に、水素原子、ハロゲン原子、ニトロ基又
は炭素数１～２４の炭化水素基を表し、該炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、
－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていてもよい。
Ｘ^１は、ニトロ基、－ＣＯ－Ｒ^５又は－ＳＯ_２－Ｒ^６を表す。
Ｒ^５及びＲ^６は、それぞれ独立に、炭素数１～２４の炭化水素基を表し、該炭化水素基
に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていて
もよい。
ＺＩ^＋は、有機カチオンを表す。］
［２］Ｘ^１が、ニトロ基、メタンスルホニル基、メチルカルボニル基又はメトキシカル
ボニル基である［１］記載のレジスト組成物。
［３］Ｒ^１が、ハロゲン原子である［１］又は［２］記載のレジスト組成物。
［４］酸発生剤が、式（Ｂ１）で表される塩である［１］～［３］のいずれかに記載の
レジスト組成物。

［式（Ｂ１）中、
Ｑ^ｂ１及びＱ^ｂ２は、それぞれ独立に、フッ素原子又は炭素数１～６のペルフルオロア
ルキル基を表す。
Ｌ^ｂ１は、炭素数１～２４の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれ
る－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含
まれる水素原子は、フッ素原子又はヒドロキシ基で置換されていてもよい。
Ｙは、置換基を有していてもよいメチル基又は置換基を有していてもよい炭素数３～１
８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－
ＳＯ_２－又は－ＣＯ－に置き換わっていてもよい。
Ｚ１^＋は、有機カチオンを表す。］
［５］酸発生剤から発生する酸よりも酸性度の弱い酸を発生する塩をさらに含有する［
１］～［４］のいずれかに記載のレジスト組成物。
［６］（１）［１］～［５］のいずれかに記載のレジスト組成物を基板上に塗布する工
程、
（２）塗布後の組成物を乾燥させて組成物層を形成する工程、
（３）組成物層に露光する工程、
（４）露光後の組成物層を加熱する工程、及び
（５）加熱後の組成物層を現像する工程、
を含むレジストパターンの製造方法。
［７］式（Ｉ）で表される塩。

［式（Ｉ）中、
Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、それぞれ独立に、水素原子、ハロゲン原子、ニトロ基又
は炭素数１～２４の炭化水素基を表し、該炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、
－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていてもよい。
Ｘ^１は、ニトロ基、－ＣＯ－Ｒ^５又は－ＳＯ_２－Ｒ^６を表す。
Ｒ^５及びＲ^６は、それぞれ独立に、炭素数１～２４の炭化水素基を表し、該炭化水素基
に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていて
もよい。
ＺＩ^＋は、有機カチオンを表す。］ The present invention includes the following inventions.
[1] A resist composition comprising: an acid generator; a resin that contains at least one structural unit selected from the group consisting of structural units represented by formula (a1-1) and structural units represented by formula (a1-2), and a structural unit represented by formula (a2-A); and a salt represented by formula (I).

[In formula (a1-1) and formula (a1-2),
L ^a1 and L ^a2 each independently represent -O- or *-O-(CH ₂ ) _k1 -CO-O
k1 represents an integer of 1 to 7, and * represents a bond to --CO--.
R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group.
R ^a6 and R ^a7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or a combination thereof.
m1 represents an integer of 0 to 14.
n1 represents an integer of 0 to 10.
n1' represents an integer of 0 to 3.

[In formula (a2-A),
R ^a50 represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
R ^a51 represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, an acryloyloxy group or a methacryloyloxy group.
A ^a50 represents a single bond or ^* -X ^a51 -(A ^a52 -X ^a52 ) _na -, where * represents a bond to the carbon atom to which -R ^a50 is bonded.
A ^a52 represents an alkanediyl group having 1 to 6 carbon atoms.
X ^a51 and X ^a52 each independently represent —O—, —CO—O— or —O—CO—.
na represents 0 or 1.
mb represents an integer of 0 to 4. When mb is an integer of 2 or more, multiple R ^a51 may be the same or different.

[In formula (I),
R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group or a hydrocarbon group having 1 to 24 carbon atoms, and the -CH ₂ - contained in the hydrocarbon group is -O-,
It may be replaced by --S--, --CO-- or --SO ₂ --.
^X1 represents a nitro group, —CO— ^R5 or —SO ₂ ^—R6 .
R ⁵ and R ⁶ each independently represent a hydrocarbon group having 1 to 24 carbon atoms, and --CH ₂ -- contained in the hydrocarbon group may be replaced by --O--, --S--, --CO-- or --SO ₂ --.
ZI ⁺ represents an organic cation.
[2] The resist composition according to [1], wherein X ¹ is a nitro group, a methanesulfonyl group, a methylcarbonyl group, or a methoxycarbonyl group.
[3] The resist composition according to [1] or [2], wherein R ¹ is a halogen atom.
[4] The resist composition according to any one of [1] to [3], wherein the acid generator is a salt represented by formula (B1):

[In formula (B1),
Q ^b1 and Q ^b2 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms.
L ^b1 represents a divalent saturated hydrocarbon group having 1 to 24 carbon atoms, in which -CH ₂ - may be replaced by -O- or -CO-, and in which a hydrogen atom may be replaced by a fluorine atom or a hydroxyl group.
Y is a methyl group which may have a substituent or a substituted group having 3 to 1 carbon atoms.
The —CH ₂ — contained in the alicyclic hydrocarbon group represents an —O—, —
It may be replaced by SO ₂ -- or --CO--.
Z1 ⁺ represents an organic cation.
[5] The composition further contains a salt that generates an acid having a weaker acidity than the acid generated from the acid generator.
The resist composition according to any one of items 1 to 4.
[6] (1) A step of applying the resist composition according to any one of [1] to [5] onto a substrate;
(2) A step of drying the applied composition to form a composition layer;
(3) exposing the composition layer to light;
(4) a step of heating the composition layer after exposure; and (5) a step of developing the composition layer after heating.
A method for producing a resist pattern comprising the steps of:
[7] A salt represented by formula (I).

[In formula (I),
R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group or a hydrocarbon group having 1 to 24 carbon atoms, and the -CH ₂ - contained in the hydrocarbon group is -O-,
It may be replaced by --S--, --CO-- or --SO ₂ --.
^X1 represents a nitro group, —CO— ^R5 or —SO ₂ ^—R6 .
R ⁵ and R ⁶ each independently represent a hydrocarbon group having 1 to 24 carbon atoms, and --CH ₂ -- contained in the hydrocarbon group may be replaced by --O--, --S--, --CO-- or --SO ₂ --.
ZI ⁺ represents an organic cation.

By using a resist composition containing the salt of the present invention, good line edge roughness (
A resist pattern can be produced by the photo-resist-removal (PRE) method.

In this specification, the term "(meth)acrylic monomer" refers to a monomer having the formula "CH ₂ ═CH—CO—"
and monomers having the structure "CH ₂ ═C(CH ₃ )—CO—". Similarly, "(meth)acrylate" and "(meth)acrylic acid" respectively mean "at least one selected from the group consisting of acrylate and methacrylate" and "at least one selected from the group consisting of acrylic acid and methacrylic acid". "CH ₂ ═C(CH ₃ )—CO—" or "CH ₂ ═CH—C
When a structural unit having "O-" is exemplified, structural units having both groups are also exemplified. Furthermore, in the groups described in this specification, those which can have both a straight-chain structure and a branched structure may have either. The term "combined group" refers to a group in which two or more of the exemplified groups are bonded with their valences appropriately changed. When stereoisomers exist, all stereoisomers are included.
In this specification, the term "solids content of a resist composition" refers to the sum of all components in the resist composition excluding the solvent (E), which will be described later.

[Resist Composition]
The resist composition of the present invention contains an acid generator (hereinafter sometimes referred to as “acid generator (B)”).
and a resin (A) containing at least one structural unit selected from the group consisting of structural units represented by formula (a1-1) and structural units represented by formula (a1-2), and a structural unit represented by formula (a2-A); and a salt represented by formula (I) (hereinafter may be referred to as "salt (I)").
Furthermore, the resist composition preferably contains a quencher (hereinafter sometimes referred to as "quencher (C)") and/or a solvent (hereinafter sometimes referred to as "solvent (E)").

<Acid Generator (B)>
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), sulfones (e.g., disulfone, ketosulfone, sulfonyldiazomethane), and the like. Examples of ionic acid generators include onium salts containing onium cations (e.g., diazonium salts, phosphonium salts, sulfonium salts, iodonium salts). Examples of the anions of the onium salts include sulfonate anions, sulfonylimide anions, sulfonylmethide anions, and the like.

Examples of the acid generator (B) include those described in JP-A-63-26653 and JP-A-55-164824.
Japanese Patent Application Laid-Open Nos. 62-69263, 63-146038, 63-163452, 62-153853, 63-146029, U.S. Pat. No. 3,779,
Compounds that generate an acid when exposed to radiation, such as those described in US Pat. No. 778, US Pat. No. 3,849,137, German Patent No. 3914407, and European Patent No. 126,712, can be used. Compounds produced by known methods can also be used. The acid generator (B) can be used in combination of two or more kinds.

［式（Ｂ１）中、
Ｑ^ｂ１及びＱ^ｂ２は、それぞれ独立に、フッ素原子又は炭素数１～６のペルフルオロア
ルキル基を表す。
Ｌ^ｂ１は、炭素数１～２４の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれ
る－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水素基に含
まれる水素原子は、フッ素原子又はヒドロキシ基で置換されていてもよい。
Ｙは、置換基を有していてもよいメチル基又は置換基を有していてもよい炭素数３～１
８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－
Ｓ（Ｏ）_２－又は－ＣＯ－に置き換わっていてもよい。
Ｚ１^＋は、有機カチオンを表す。］ The acid generator (B) is preferably a fluorine-containing acid generator, more preferably represented by the formula (B1):
(hereinafter, may be referred to as "acid generator (B1)").

[In formula (B1),
Q ^b1 and Q ^b2 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms.
L ^b1 represents a divalent saturated hydrocarbon group having 1 to 24 carbon atoms, in which -CH ₂ - may be replaced by -O- or -CO-, and in which a hydrogen atom may be replaced by a fluorine atom or a hydroxyl group.
Y is a methyl group which may have a substituent or a substituted group having 3 to 1 carbon atoms.
The —CH ₂ — contained in the alicyclic hydrocarbon group represents an —O—, —
It may be replaced by S(O) ₂ -- or --CO--.
Z1 ⁺ represents an organic cation.

Examples of the perfluoroalkyl group represented by Q ^b1 and Q ^b2 include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, and a perfluorohexyl group.
It is preferable that Q ^b1 and Q ^b2 each independently represent a fluorine atom or a trifluoromethyl group, and it is more preferable that both represent a fluorine atom.

Examples of the divalent saturated hydrocarbon group for L ^b1 include a linear alkanediyl group, a branched alkanediyl group, and a monocyclic or polycyclic divalent alicyclic saturated hydrocarbon group, and may be a group formed by combining two or more of these groups.
Specifically, 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-
linear alkanediyl groups such as a 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-
branched alkanediyl groups such as a 1,3-diyl group, a 2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group, and a 2-methylbutane-1,4-diyl group;
monocyclic divalent alicyclic saturated hydrocarbon groups such as cycloalkanediyl groups, such as cyclobutane-1,3-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,4-diyl group, and cyclooctane-1,5-diyl group;
Norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-
Examples of the alkyl group include polycyclic divalent alicyclic saturated hydrocarbon groups such as 1,5-diyl group and adamantane-2,6-diyl group.

Examples of the divalent saturated hydrocarbon group represented by L ^b1 in which -CH ₂ - is replaced by -O- or -CO- include groups represented by any of formulas (b1-1) to (b1-3). In the groups represented by formulas (b1-1) to (b1-3) and specific examples thereof represented by formulas (b1-4) to (b1-11), * and ** represent bonding sites, and * represents the bonding site to -Y.

［式（ｂ１－１）中、
Ｌ^ｂ２は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^ｂ３は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよく、該飽和
炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ただし、Ｌ^ｂ２とＬ^ｂ３との炭素数合計は、２２以下である。
式（ｂ１－２）中、
Ｌ^ｂ４は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^ｂ５は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよく、該飽和
炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ただし、Ｌ^ｂ４とＬ^ｂ５との炭素数合計は、２２以下である。
式（ｂ１－３）中、
Ｌ^ｂ６は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
Ｌ^ｂ７は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよく、該飽和
炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ただし、Ｌ^ｂ６とＬ^ｂ７との炭素数合計は、２３以下である。］

[In formula (b1-1),
L ^b2 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b3 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxyl group, The --CH ₂ -- contained in the hydrocarbon group may be replaced by --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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b5 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxyl group, The --CH ₂ -- contained in the hydrocarbon group may be replaced by --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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxyl group.
L ^b7 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxyl group, The --CH ₂ -- contained in the hydrocarbon group may be replaced by --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 formulae (b1-1) to (b1-3), when --CH ₂ -- contained in the saturated hydrocarbon group is replaced with --O-- or --CO--, the number of carbon atoms before replacement is regarded as the number of carbon atoms of the saturated hydrocarbon group.
Examples of the divalent saturated hydrocarbon group include the same divalent saturated hydrocarbon groups as those represented by L ^b1 .

L ^b2 is preferably a single bond.
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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b7 is preferably a single bond or a saturated hydrocarbon group having 1 to 18 carbon atoms, in which a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group, and -CH ₂ - contained in the saturated hydrocarbon group may be substituted with -O- or -CO-.

The divalent saturated hydrocarbon group represented by L ^b1 in which one --CH ₂ -- is replaced by --O-- or --CO-- is preferably a group represented by formula (b1-1) or formula (b1-3).

［式（ｂ１－４）中、
Ｌ^ｂ８は、単結合又は炭素数１～２２の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
式（ｂ１－５）中、
Ｌ^ｂ９は、炭素数１～２０の２価の飽和炭化水素基を表し、該２価の飽和炭化水素基に
含まれる－ＣＨ_２－は－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｌ^ｂ１０は、単結合又は炭素数１～１９の２価の飽和炭化水素基を表し、該飽和炭化水
素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ９及びＬ^ｂ１０の合計炭素数は２０以下である。
式（ｂ１－６）中、
Ｌ^ｂ１１は、炭素数１～２１の２価の飽和炭化水素基を表す。
Ｌ^ｂ１２は、単結合又は炭素数１～２０の２価の飽和炭化水素基を表し、該飽和炭化水
素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ１１及びＬ^ｂ１２の合計炭素数は２１以下である。
式（ｂ１－７）中、
Ｌ^ｂ１３は、炭素数１～１９の２価の飽和炭化水素基を表す。
Ｌ^ｂ１４は、単結合又は炭素数１～１８の２価の飽和炭化水素基を表し、該２価の飽和
炭化水素基に含まれる－ＣＨ_２－は－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｌ^ｂ１５は、単結合又は炭素数１～１８の２価の飽和炭化水素基を表し、該飽和炭化水
素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ１３～Ｌ^ｂ１５の合計炭素数は１９以下である。
式（ｂ１－８）中、
Ｌ^ｂ１６は、炭素数１～１８の２価の飽和炭化水素基を表し、該２価の飽和炭化水素基
に含まれる－ＣＨ_２－は－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｌ^ｂ１７は、炭素数１～１８の２価の飽和炭化水素基を表す。
Ｌ^ｂ１８は、単結合又は炭素数１～１７の２価の飽和炭化水素基を表し、該飽和炭化水
素基に含まれる水素原子は、フッ素原子又はヒドロキシ基に置換されていてもよい。
ただし、Ｌ^ｂ１６～Ｌ^ｂ１８の合計炭素数は１９以下である。］ Examples of the group represented by formula (b1-1) include groups represented by formulas (b1-4) to (b1-8).

[In formula (b1-4),
L ^b8 represents a single bond or a divalent saturated hydrocarbon group having 1 to 22 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
In formula (b1-5),
L ^b9 represents a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and --CH ₂ -- contained in the divalent saturated hydrocarbon group may be replaced by --O-- or --CO--.
L ^b10 represents a single bond or a divalent saturated hydrocarbon group having 1 to 19 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
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 having 1 to 21 carbon atoms.
L ^b12 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
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 having 1 to 19 carbon atoms.
L ^b14 represents a single bond or a divalent saturated hydrocarbon group having 1 to 18 carbon atoms, and --CH ₂ -- 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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
However, the total number of carbon atoms of 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 --CH ₂ -- contained in the divalent saturated hydrocarbon group may be replaced by --O-- or --CO--.
L ^b17 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms.
L ^b18 represents a single bond or a divalent saturated hydrocarbon group having 1 to 17 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom or a hydroxy group.
However, the total number of carbon atoms of 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.

式（ｂ１－９）中、
Ｌ^b19は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^b20は、単結合又は炭素数１～２３の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子、ヒドロキシ基又はアルキルカルボニルオキシ基に
置換されていてもよい。該アルキルカルボニルオキシ基に含まれる－ＣＨ₂－は、－Ｏ－
又は－ＣＯ－に置き換わっていてもよく、該アルキルカルボニルオキシ基に含まれる水素
原子は、ヒドロキシ基に置換されていてもよい。
ただし、Ｌ^b19及びＬ^b20の合計炭素数は２３以下である。
式（ｂ１－１０）中、
Ｌ^b21は、単結合又は炭素数１～２１の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^b22は、単結合又は炭素数１～２１の２価の飽和炭化水素基を表す。
Ｌ^b23は、単結合又は炭素数１～２１の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子、ヒドロキシ基又はアルキルカルボニルオキシ基に
置換されていてもよい。該アルキルカルボニルオキシ基に含まれる－ＣＨ₂－は、－Ｏ－
又は－ＣＯ－に置き換わっていてもよく、該アルキルカルボニルオキシ基に含まれる水素
原子は、ヒドロキシ基に置換されていてもよい。
ただし、Ｌ^b21、Ｌ^b22及びＬ^b23の合計炭素数は２１以下である。
式（ｂ１－１１）中、
Ｌ^b24は、単結合又は炭素数１～２０の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子に置換されていてもよい。
Ｌ^b25は、炭素数１～２１の２価の飽和炭化水素基を表す。
Ｌ^b26は、単結合又は炭素数１～２０の２価の飽和炭化水素基を表し、該飽和炭化水素
基に含まれる水素原子は、フッ素原子、ヒドロキシ基又はアルキルカルボニルオキシ基に
置換されていてもよい。該アルキルカルボニルオキシ基に含まれる－ＣＨ₂－は、－Ｏ－
又は－ＣＯ－に置き換わっていてもよく、該アルキルカルボニルオキシ基に含まれる水素
原子は、ヒドロキシ基に置換されていてもよい。
ただし、Ｌ^b24、Ｌ^b25及びＬ^b26の合計炭素数は２１以下である。 Examples of the group represented by formula (b1-3) include groups represented by formulas (b1-9) to (b1-11).

In formula (b1-9),
L ^b19 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b20 represents a single bond or a divalent saturated hydrocarbon group having 1 to 23 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom, a hydroxyl group or an alkylcarbonyloxy group. The --CH ₂ -- contained in the alkylcarbonyloxy group is --O--
Or, a hydrogen atom contained in the alkylcarbonyloxy group may be substituted by —CO—, and a hydrogen atom contained in the alkylcarbonyloxy group may be substituted by a hydroxy group.
However, the total number of carbon atoms of L ^b19 and L ^b20 is 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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom, a hydroxyl group or an alkylcarbonyloxy group. The --CH ₂ -- contained in the alkylcarbonyloxy group is --O--
Or, a hydrogen atom contained in the alkylcarbonyloxy group may be substituted by —CO—, and a hydrogen atom contained in the alkylcarbonyloxy group may be substituted by a hydroxy group.
However, the total number of carbon atoms of 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 a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom.
L ^b25 represents a divalent saturated hydrocarbon group having 1 to 21 carbon atoms.
L ^b26 represents a single bond or a divalent saturated hydrocarbon group having 1 to 20 carbon atoms, and a hydrogen atom contained in the saturated hydrocarbon group may be substituted with a fluorine atom, a hydroxyl group or an alkylcarbonyloxy group. The --CH ₂ -- contained in the alkylcarbonyloxy group is --O--
Or, a hydrogen atom contained in the alkylcarbonyloxy group may be substituted by —CO—, and a hydrogen atom contained in the alkylcarbonyloxy group may be substituted by a hydroxy group.
However, the total number of carbon atoms of L ^b24 , L ^b25 and L ^b26 is 21 or less.

In addition, in the groups represented by formulae (b1-9) to (b1-11), when a hydrogen atom contained in the saturated hydrocarbon group is substituted with an alkylcarbonyloxy group,
The number of carbon atoms before substitution is regarded as the number of carbon atoms of the saturated hydrocarbon group.

Examples of the alkylcarbonyloxy group include an acetyloxy group, a propionyloxy group, a butyryloxy group, a cyclohexylcarbonyloxy group, and an adamantylcarbonyloxy group.

Examples of the group represented by formula (b1-4) include the following.

Examples of the group represented by formula (b1-5) include the following.

Examples of the group represented by formula (b1-6) include the following.

Examples of the group represented by formula (b1-7) include the following.

Examples of the group represented by formula (b1-8) include the following.

Examples of the group represented by formula (b1-2) include the following.

Examples of the group represented by formula (b1-9) include the following.

Examples of the group represented by formula (b1-10) include the following.

Examples of the group represented by formula (b1-11) include the following.

The alicyclic hydrocarbon group represented by Y includes those represented by the formulae (Y1) to (Y11), (Y36) to (Y38)
Examples of the group include a group represented by the formula (Y38).
The —CH ₂ — contained in the alicyclic hydrocarbon group represented by Y is —O—, —S(O) ₂ — or —
When it is replaced by CO-, the number may be 1 or may be 2 or more. Examples of such a group include groups represented by formulae (Y12) to (Y35) and formulae (Y39) to (Y41).

Ｙで表される脂環式炭化水素基としては、好ましくは式（Ｙ１）～式（Ｙ２０）、式（
Ｙ２６）、式（Ｙ２７）、式（Ｙ３０）、式（Ｙ３１）、式（Ｙ３９）～式（Ｙ４０）の
いずれかで表される基であり、より好ましくは式（Ｙ１１）、式（Ｙ１５）、式（Ｙ１６
）、式（Ｙ２０）、式（Ｙ２６）、式（Ｙ２７）、式（Ｙ３０）～式（Ｙ３１）又は式（
Ｙ３９）～式（Ｙ４０）で表される基であり、さらに好ましくは式（Ｙ１１）、式（Ｙ１
５）、式（Ｙ２０）、式（Ｙ３０）、式（Ｙ３９）又は式（Ｙ４０）で表される基である
。
Ｙで表される脂環式炭化水素基が式（Ｙ２８）～式（Ｙ３５）、式（Ｙ３９）又は式（
Ｙ４０）等の、酸素原子を含むスピロ環である場合には、２つの酸素原子間のアルカンジ
イル基は、１以上のフッ素原子を有することが好ましい。また、ケタール構造に含まれる
アルカンジイル基のうち、酸素原子に隣接するメチレン基には、フッ素原子が置換されて
いないのが好ましい。

The alicyclic hydrocarbon group represented by Y is preferably one represented by the formula (Y1) to the formula (Y20),
Y26), (Y27), (Y30), (Y31), (Y39) to (Y40), and more preferably, (Y11), (Y15), (Y16)
), Formula (Y20), Formula (Y26), Formula (Y27), Formula (Y30) to Formula (Y31) or Formula (
Y39) to (Y40), and more preferably, Y11, Y12, Y13, Y14, Y15, Y16, Y17, Y18, Y19, Y20, Y210, Y211, Y222,
5), a group represented by formula (Y20), formula (Y30), formula (Y39) or formula (Y40).
The alicyclic hydrocarbon group represented by Y is represented by the formula (Y28) to the formula (Y35), the formula (Y39) or the formula (Y40).
In the case of a spiro ring containing an oxygen atom, such as Y40, the alkanediyl group between the two oxygen atoms preferably has one or more fluorine atoms. In addition, among the alkanediyl groups contained in the ketal structure, it is preferable that the methylene group adjacent to the oxygen atom is not substituted with a fluorine atom.

The substituent of the methyl group represented by Y is a halogen atom, a hydroxyl group, a C3-C1
6 alicyclic hydrocarbon group, an aromatic hydrocarbon group having 6 to 18 carbon atoms, a glycidyloxy group, -(
CH ₂ ) _ja -CO-O-R ^b1 group or -(CH ₂ ) _ja -O-CO-R ^b1 group (in the formula,
R ^b1 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 combination thereof. ja represents an integer of 0 to 4. -CH ₂ - contained in the alkyl group having 1 to 16 carbon atoms and the alicyclic hydrocarbon group having 3 to 16 carbon atoms may be replaced by -O-, -S(O) ₂ - or -CO-.
Examples of the substituent of the alicyclic hydrocarbon group represented by Y include a halogen atom, a hydroxy group, an alkyl group having 1 to 12 carbon atoms which may be substituted by a hydroxy group, an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, an aralkyl group having 7 to 21 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, a glycidyloxy group, a -(CH ₂ ) _ja -CO-O-R ^b1 group or a -(CH ₂ ) _ja -O-CO-R ^b1 group (
In the formula, R ^b1 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 combination thereof.
represents any one of the integers shown below. The —CH ₂ — contained in the alkyl group having 1 to 16 carbon atoms and the alicyclic hydrocarbon group having 3 to 16 carbon atoms may be replaced by —O—, —S(O) ₂ — or —CO—.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alicyclic hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a norbornyl group, and an adamantyl group.
The alicyclic hydrocarbon group may have a chain hydrocarbon group, such as a methylcyclohexyl group or a dimethylcyclohexyl group.
Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a biphenylyl group, a naphthyl group, and a phenanthryl group.
The aromatic hydrocarbon group may have a chain hydrocarbon group or an alicyclic hydrocarbon group, and is preferably an aromatic hydrocarbon group having a chain hydrocarbon group having 1 to 18 carbon atoms (e.g., a tolyl group, a xylyl group, a cumenyl group, a mesityl group, a p-ethylphenyl group, a p-tert-butylphenyl group, a 2,6-
diethylphenyl group, 2-methyl-6-ethylphenyl group, etc.), and aromatic hydrocarbon groups having an alicyclic hydrocarbon group having 3 to 18 carbon atoms (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.).
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group.
Examples of the alkyl group substituted with a hydroxy group include hydroxyalkyl groups such as a hydroxymethyl group and a hydroxyethyl group.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a decyloxy group, and a dodecyloxy group.
Examples of the aralkyl group include a benzyl group, a phenethyl group, a phenylpropyl group, a naphthylmethyl group, and a naphthylethyl group.
Examples of the alkylcarbonyl group include an acetyl group, a propionyl group, and a butyryl group.

Examples of Y include the following.

Y is preferably an alicyclic hydrocarbon group having 3 to 18 carbon atoms which may have a substituent, and more preferably an adamantyl group which may have a substituent, in which -CH ₂ - constituting the alicyclic hydrocarbon group or the adamantyl group may be replaced by -CO-, -S(O) ₂ - or -CO-. Y is further preferably an adamantyl group, a hydroxyadamantyl group, an oxoadamantyl group or a group represented by the following:

The anion in the salt represented by formula (B1) is selected from the group consisting of the anions represented by formulae (B1-A-1) to (B1-A-2).
A-55) (hereinafter, it may be referred to as "anion (B1-A-1)" depending on the formula number.) is preferable, and the anions represented by the formulas (B1-A-1) to (B1-A-4) and (B1
-A-9), Formula (B1-A-10), Formula (B1-A-24) to Formula (B1-A-33), Formula (B1-A-36) to Formula (B1-A-40), Formula (B1-A-47) to Formula (B1-A-5)
5) is more preferable.

ここで、Ｒ^ｉ２～Ｒ^ｉ７は、それぞれ独立に、例えば、炭素数１～４のアルキル基、好
ましくはメチル基又はエチル基である。Ｒ^ｉ８は、例えば、炭素数１～１２の脂肪族炭化
水素基、好ましくは炭素数１～４のアルキル基、炭素数５～１２の脂環式炭化水素基又は
これらを組合せることにより形成される基、より好ましくはメチル基、エチル基、シクロ
ヘキシル基又はアダマンチル基である。Ｌ^Ａ４は、単結合又は炭素数１～４のアルカンジ
イル基である。Ｑ^ｂ１及びＱ^ｂ２は、上記と同じ意味を表す。
式（Ｂ１）で表される塩におけるアニオンとしては、具体的には、特開２０１０－２０
４６４６号公報に記載されたアニオンが挙げられる。

Here, R ⁱ² to R ⁱ⁷ are each independently, for example, an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group. ^{R i8} is, for example, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group having 5 to 12 carbon atoms, or a group formed by combining these, more preferably a methyl group, an ethyl group, a cyclohexyl group, or an adamantyl group. ^{L A4} is a single bond or an alkanediyl group having 1 to 4 carbon atoms. Q ^b1 and Q ^b2 have the same meaning as above.
Specific examples of the anion in the salt represented by formula (B1) include those described in JP-A-2010-20
Examples of the anions include those described in US Pat. No. 4,646.

The anion in the salt represented by formula (B1) is preferably a compound represented by formula (B1a-1) to formula (B1a-2)
B1a-34) are examples of anions.

Among them, the compounds represented by formula (B1a-1) to formula (B1a-3) and the compounds represented by formula (B1a-7) to formula (B1a-
16), formula (B1a-18), formula (B1a-19), formula (B1a-22) to formula (B1a-
30) is preferably an anion represented by any one of the following formulas:

The organic cation of Z1 ⁺ may be an organic onium cation, an organic sulfonium cation,
Examples of the cation include an organic iodonium cation, an organic ammonium cation, a benzothiazolium cation, and an organic phosphonium cation. Among these, an organic sulfonium cation and an organic iodonium cation are preferred, and an arylsulfonium cation is more preferred. Specific examples include cations represented by any one of formulas (b2-1) to (b2-4) (hereinafter, sometimes referred to as "cation (b2-1)" depending on the formula number).

式（ｂ２－１）～式（ｂ２－４）において、
Ｒ^b4～Ｒ^b6は、それぞれ独立に、炭素数１～３０の鎖式炭化水素基、炭素数３～３６の
脂環式炭化水素基又は炭素数６～３６の芳香族炭化水素基を表し、該鎖式炭化水素基に含
まれる水素原子は、ヒドロキシ基、炭素数１～１２のアルコキシ基、炭素数３～１２の脂
環式炭化水素基又は炭素数６～１８の芳香族炭化水素基で置換されていてもよく、該脂環
式炭化水素基に含まれる水素原子は、ハロゲン原子、炭素数１～１８の脂肪族炭化水素基
、炭素数２～４のアルキルカルボニル基又はグリシジルオキシ基で置換されていてもよく
、該芳香族炭化水素基に含まれる水素原子は、ハロゲン原子、ヒドロキシ基又は炭素数１
～１２のアルコキシ基で置換されていてもよい。
Ｒ^b4とＲ^b5とは、互いに結合してそれらが結合する硫黄原子と一緒になって環を形成し
てもよく、該環に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わっても
よい。
Ｒ^b7及びＲ^b8は、それぞれ独立に、ヒドロキシ基、炭素数１～１２の脂肪族炭化水素基
又は炭素数１～１２のアルコキシ基を表す。
ｍ２及びｎ２は、それぞれ独立に０～５のいずれかの整数を表す。
ｍ２が２以上のとき、複数のＲ^b7は同一でも異なってもよく、ｎ２が２以上のとき、複
数のＲ^b8は同一でも異なってもよい。
Ｒ^b9及びＲ^b10は、それぞれ独立に、炭素数１～３６の鎖式炭化水素基又は炭素数３～
３６の脂環式炭化水素基を表す。
Ｒ^b9とＲ^b10とは、互いに結合してそれらが結合する硫黄原子と一緒になって環を形成
してもよく、該環に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わって
もよい。
Ｒ^b11は、水素原子、炭素数１～３６の鎖式炭化水素基、炭素数３～３６の脂環式炭化
水素基又は炭素数６～１８の芳香族炭化水素基を表す。
Ｒ^b12は、炭素数１～１２の鎖式炭化水素基、炭素数３～１８の脂環式炭化水素基又は
炭素数６～１８の芳香族炭化水素基を表し、該鎖式炭化水素に含まれる水素原子は、炭素
数６～１８の芳香族炭化水素基で置換されていてもよく、該芳香族炭化水素基に含まれる
水素原子は、炭素数１～１２のアルコキシ基又は炭素数１～１２のアルキルカルボニルオ
キシ基で置換されていてもよい。
Ｒ^b11とＲ^b12とは、互いに結合してそれらが結合する－ＣＨ－ＣＯ－を含めて環を形成
していてもよく、該環に含まれる－ＣＨ₂－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わ
ってもよい。
Ｒ^b13～Ｒ^b18は、それぞれ独立に、ヒドロキシ基、炭素数１～１２の脂肪族炭化水素基
又は炭素数１～１２のアルコキシ基を表す。
Ｌ^b31は、硫黄原子又は酸素原子を表す。
ｏ２、ｐ２、ｓ２、及びｔ２は、それぞれ独立に、０～５のいずれかの整数を表す。
ｑ２及びｒ２は、それぞれ独立に、０～４のいずれかの整数を表す。
ｕ２は０又は１を表す。
ｏ２が２以上のとき、複数のＲ^b13は同一又は相異なり、ｐ２が２以上のとき、複数の
Ｒ^b14は同一又は相異なり、ｑ２が２以上のとき、複数のＲ^b15は同一又は相異なり、ｒ２
が２以上のとき、複数のＲ^b16は同一又は相異なり、ｓ２が２以上のとき、複数のＲ^b17は
同一又は相異なり、ｔ２が２以上のとき、複数のＲ^b18は同一又は相異なる。
脂肪族炭化水素基とは、鎖式炭化水素基及び脂環式炭化水素基を表す。
鎖式炭化水素基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル
基、ｓｅｃ－ブチル基、ｔｅｒｔ－ブチル基、ペンチル基、ヘキシル基、オクチル基及び
２－エチルヘキシル基のアルキル基等が挙げられる。
特に、Ｒ^b9～Ｒ^b12の鎖式炭化水素基は、好ましくは炭素数１～１２である。
脂環式炭化水素基としては、単環式又は多環式のいずれでもよく、単環式の脂環式炭化
水素基としては、シクロプロピル基、シクロブチル基、シクロペンチル基、シクロへキシ
ル基、シクロヘプチル基、シクロオクチル基、シクロデシル基等のシクロアルキル基等が
挙げられる。多環式の脂環式炭化水素基としては、デカヒドロナフチル基、アダマンチル
基、ノルボルニル基及び下記の基等が挙げられる。

特に、Ｒ^b9～Ｒ^b12の脂環式炭化水素基は、好ましくは炭素数３～１８、より好ましく
は炭素数４～１２である。
水素原子が脂肪族炭化水素基で置換された脂環式炭化水素基としては、メチルシクロヘ
キシル基、ジメチルシクロへキシル基、２－メチルアダマンタン－２－イル基、２－エチ
ルアダマンタン－２－イル基、２－イソプロピルアダマンタン－２－イル基、メチルノル
ボルニル基、イソボルニル基等が挙げられる。水素原子が脂肪族炭化水素基で置換された
脂環式炭化水素基においては、脂環式炭化水素基と脂肪族炭化水素基との合計炭素数が好
ましくは２０以下である。
芳香族炭化水素基としては、フェニル基、ビフェニル基、ナフチル基、フェナントリル
基等のアリール基が挙げられる。芳香族炭化水素基は、鎖式炭化水素基又は脂環式炭化水
素基を有していてもよく、鎖式炭化水素基を有する芳香族炭化水素基（トリル基、キシリ
ル基、クメニル基、メシチル基、ｐ－エチルフェニル基、ｐ－ｔｅｒｔ－ブチルフェニル
基、２，６－ジエチルフェニル基、２－メチル－６－エチルフェニル基等）及び脂環式炭
化水素基を有する芳香族炭化水素基（ｐ－シクロへキシルフェニル基、ｐ－アダマンチル
フェニル基等）等が挙げられる。なお、芳香族炭化水素基が、鎖式炭化水素基又は脂環式
炭化水素基を有する場合は、炭素数１～１８の鎖式炭化水素基及び炭素数３～１８の脂環
式炭化水素基が好ましい。
水素原子がアルコキシ基で置換された芳香族炭化水素基としては、ｐ－メトキシフェニ
ル基等が挙げられる。
水素原子が芳香族炭化水素基で置換された鎖式炭化水素基としては、ベンジル基、フェ
ネチル基、フェニルプロピル基、トリチル基、ナフチルメチル基、ナフチルエチル基等の
アラルキル基等が挙げられる。
アルコキシ基としては、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基、ペンチ
ルオキシ基、ヘキシルオキシ基、ヘプチルオキシ基、オクチルオキシ基、デシルオキシ基
及びドデシルオキシ基等が挙げられる。
アルキルカルボニル基としては、アセチル基、プロピオニル基及びブチリル基等が挙げ
られる。
ハロゲン原子としては、フッ素原子、塩素原子、臭素原子及びヨウ素原子等が挙げられ
る。
アルキルカルボニルオキシ基としては、メチルカルボニルオキシ基、エチルカルボニル
オキシ基、プロピルカルボニルオキシ基、イソプロピルカルボニルオキシ基、ブチルカル
ボニルオキシ基、ｓｅｃ－ブチルカルボニルオキシ基、ｔｅｒｔ－ブチルカルボニルオキ
シ基、ペンチルカルボニルオキシ基、ヘキシルカルボニルオキシ基、オクチルカルボニル
オキシ基及び２－エチルヘキシルカルボニルオキシ基等が挙げられる。
Ｒ^b4とＲ^b5とが互いに結合してそれらが結合する硫黄原子と一緒になって形成する環は
、単環式、多環式、芳香族性、非芳香族性、飽和及び不飽和のいずれの環であってもよい
。この環は、炭素数３～１８の環が挙げられ、好ましくは炭素数４～１８の環である。ま
た、硫黄原子を含む環は、３員環～１２員環が挙げられ、好ましくは３員環～７員環であ
り、例えば下記の環等が挙げられる。＊は結合部位を表す。

Ｒ^b9とＲ^b10とが一緒になって形成する環は、単環式、多環式、芳香族性、非芳香族性
、飽和及び不飽和のいずれの環であってもよい。この環は、３員環～１２員環が挙げられ
、好ましくは３員環～７員環である。例えば、チオラン－１－イウム環（テトラヒドロチ
オフェニウム環）、チアン－１－イウム環、１，４－オキサチアン－４－イウム環等が挙
げられる。
Ｒ^b11とＲ^b12とが一緒になって形成する環は、単環式、多環式、芳香族性、非芳香族性
、飽和及び不飽和のいずれの環であってもよい。この環は、３員環～１２員環が挙げられ
、好ましくは３員環～７員環である。オキソシクロヘプタン環、オキソシクロヘキサン環
、オキソノルボルナン環、オキソアダマンタン環等が挙げられる。

In formulas (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, a hydrogen atom contained in the chain hydrocarbon group may be substituted with a hydroxy 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, a hydrogen atom contained 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, and a hydrogen atom contained in the aromatic hydrocarbon group may be substituted with a halogen atom, a hydroxy group, or 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.
It may be substituted with an alkoxy group having 1 to 12 carbon atoms.
R ^b4 and R ^b5 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, and --CH ₂ -- contained in the ring may be replaced by --O--, --S-- or --CO--.
R ^b7 and R ^b8 each independently represent a hydroxy group, an aliphatic hydrocarbon 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 of 0 to 5.
When m2 is 2 or more, multiple R ^b7s may be the same or different, and when n2 is 2 or more, multiple R ^b8s may be the same or different.
R ^b9 and R ^b10 each independently represent a chain hydrocarbon group having 1 to 36 carbon atoms or a group having 3 to 4 carbon atoms.
Represents 36 alicyclic hydrocarbon groups.
R ^b9 and R ^b10 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, and --CH ₂ -- contained in the ring may be replaced by --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 an open 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, a hydrogen atom contained in the open chain hydrocarbon may be substituted with an aromatic hydrocarbon group having 6 to 18 carbon atoms, and a hydrogen atom contained 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 be bonded to each other to form a ring including the --CH--CO-- to which they are bonded, and --CH ₂ -- contained in the ring may be replaced by --O--, --S-- or --CO--.
R ^b13 to R ^b18 each independently represent a hydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
L ^b31 represents a sulfur atom or an oxygen atom.
o2, p2, s2, and t2 each independently represent an integer of 0 to 5.
q2 and r2 each independently represent an integer of 0 to 4.
u2 represents 0 or 1.
When o2 is 2 or more, a plurality of R ^b13 are the same or different; when p2 is 2 or more, a plurality of R ^b14 are the same or different; when q2 is 2 or more, a plurality of R ^b15 are the same or different;
When s2 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.
The aliphatic hydrocarbon group refers to a chain hydrocarbon group and an alicyclic hydrocarbon group.
Examples of the chain hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl and 2-ethylhexyl groups.
In particular, the chain hydrocarbon groups of R ^b9 to R ^b12 preferably have 1 to 12 carbon atoms.
The alicyclic hydrocarbon group may be either monocyclic or polycyclic, and examples of the monocyclic alicyclic hydrocarbon group include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl. Examples of the polycyclic alicyclic hydrocarbon group include decahydronaphthyl, adamantyl, and norbornyl groups, as well as the following groups:

In particular, the alicyclic hydrocarbon groups of R ^b9 to R ^b12 preferably have 3 to 18 carbon atoms, and more preferably have 4 to 12 carbon atoms.
Examples of the alicyclic hydrocarbon group in which a hydrogen atom is substituted with an aliphatic hydrocarbon group include a methylcyclohexyl group, a dimethylcyclohexyl group, a 2-methyladamantan-2-yl group, a 2-ethyladamantan-2-yl group, a 2-isopropyladamantan-2-yl group, a methylnorbornyl group, an isobornyl group, etc. In the alicyclic hydrocarbon group 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.
Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a biphenyl group, a naphthyl group, and a phenanthryl group. The aromatic hydrocarbon group may have a chain hydrocarbon group or an alicyclic hydrocarbon group, and examples of the aromatic hydrocarbon group include an aromatic hydrocarbon group having a chain hydrocarbon group (such as a tolyl group, a xylyl group, a cumenyl group, a mesityl group, a p-ethylphenyl group, a p-tert-butylphenyl group, a 2,6-diethylphenyl group, and a 2-methyl-6-ethylphenyl group) and an aromatic hydrocarbon group having an alicyclic hydrocarbon group (such as a p-cyclohexylphenyl group and a p-adamantylphenyl group). When the aromatic hydrocarbon group has a chain hydrocarbon group or an alicyclic hydrocarbon group, a chain hydrocarbon group having 1 to 18 carbon atoms and an alicyclic hydrocarbon group having 3 to 18 carbon atoms are preferred.
An example of the aromatic hydrocarbon group in which a hydrogen atom is substituted with an alkoxy group is a p-methoxyphenyl group.
Examples of the chain hydrocarbon group in which a hydrogen atom has been substituted with an aromatic hydrocarbon group include aralkyl groups such as a benzyl group, a phenethyl group, a phenylpropyl group, a trityl group, a naphthylmethyl group, and a naphthylethyl group.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a decyloxy group, and a dodecyloxy group.
Examples of the alkylcarbonyl group include an acetyl group, a propionyl group, and a butyryl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkylcarbonyloxy group include a methylcarbonyloxy group, an ethylcarbonyloxy group, a propylcarbonyloxy group, an isopropylcarbonyloxy group, a butylcarbonyloxy group, a sec-butylcarbonyloxy group, a tert-butylcarbonyloxy group, a pentylcarbonyloxy group, a hexylcarbonyloxy group, an octylcarbonyloxy group, and a 2-ethylhexylcarbonyloxy group.
The ring formed by R ^b4 and R ^b5 bonding to each other together with the sulfur atom to which they are bonded may be any of monocyclic, polycyclic, aromatic, non-aromatic, saturated and unsaturated rings. Examples of this ring include rings having 3 to 18 carbon atoms, and preferably rings having 4 to 18 carbon atoms. Examples of the ring containing a sulfur atom include 3- to 12-membered rings, and preferably 3- to 7-membered rings, such as the rings shown below. * represents a bonding site.

The ring formed by R ^b9 and R ^b10 together may be any of monocyclic, polycyclic, aromatic, non-aromatic, saturated and unsaturated rings. This ring may be a 3- to 12-membered ring, preferably a 3- to 7-membered ring. Examples of the ring include a thiolane-1-ium ring (tetrahydrothiophenium ring), a thian-1-ium ring, and a 1,4-oxathiane-4-ium ring.
The ring formed by R ^b11 and R ^b12 together may be any of monocyclic, polycyclic, aromatic, non-aromatic, saturated and unsaturated rings. This ring may be a 3- to 12-membered ring, preferably a 3- to 7-membered ring. Examples of the ring include an oxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, and an oxoadamantane ring.

Among the cations (b2-1) to (b2-4), the cation (b2
-1).
Examples of the cation (b2-1) include the following cations.

Examples of the cation (b2-2) include the following cations.

Examples of the cation (b2-3) include the following cations.

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

The acid generator (B) is a combination of the above-mentioned anion and the above-mentioned organic cation, which can be combined in any desired manner. The acid generator (B) is preferably represented by the formula (B1a-1) to
Examples of the combination of an anion represented by any one of formulas (B1a-3), (B1a-7) to (B1a-16), (B1a-18), (B1a-19), and (B1a-22) to (B1a-34) and a cation (b2-1) or a cation (b2-3) are mentioned.

The acid generator (B) is preferably one represented by formula (B1-1) to formula (B1-48). Among them, an acid generator containing an arylsulfonium cation is preferable.
Formula (B1-1) to Formula (B1-3), Formula (B1-5) to Formula (B1-7), Formula (B1-11)
~Formula (B1-14), Formula (B1-20) ~Formula (B1-26), Formula (B1-29), Formula (B
Those represented by formulas (B1-31) to (B1-48) are particularly preferred.

In the resist composition of the present invention, the content of the acid generator is preferably from 1 to 40 parts by mass, more preferably from 5 to 40 parts by mass, even more preferably from 5 to 35 parts by mass, and still more preferably from 10 to 35 parts by mass, relative to 100 parts by mass of the resin (A). The resist composition of the present invention may contain one type of acid generator (B) alone, or may contain multiple types.

<Resin (A)>
The resist composition of the present invention comprises a structural unit represented by formula (a1-1) (hereinafter referred to as structural unit (a
The resin (hereinafter may be referred to as "resin (A)") includes at least one structural unit selected from the group consisting of a structural unit represented by formula (a1-1) and a structural unit represented by formula (a1-2) (hereinafter may be referred to as structural unit (a1-2)), and a structural unit represented by formula (a2-A) (hereinafter may be referred to as structural unit (a2-A)).

［式（ａ１－１）及び式（ａ１－２）中、
Ｌ^ａ１及びＬ^ａ２は、それぞれ独立に、－Ｏ－又は＊－Ｏ－（ＣＨ_２）_ｋ１－ＣＯ－Ｏ
－を表し、ｋ１は１～７のいずれかの整数を表し、＊は－ＣＯ－との結合手を表す。
Ｒ^ａ４及びＲ^ａ５は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^ａ６及びＲ^ａ７は、それぞれ独立に、炭素数１～８のアルキル基、炭素数３～１８の
脂環式炭化水素基又はこれらを組合せた基を表す。
ｍ１は、０～１４のいずれかの整数を表す。
ｎ１は、０～１０のいずれかの整数を表す。
ｎ１’は、０～３のいずれかの整数を表す。］ <Structural unit (a1-1) and structural unit (a1-2)>
The structural unit (a1-1) and the structural unit (a1-2) are structural units having an acid labile group and are represented by the following formula: Here, the acid labile group means a group that has a leaving group and is eliminated upon contact with an acid to form a hydrophilic group (for example, a hydroxy group or a carboxy group).

[In formula (a1-1) and formula (a1-2),
L ^a1 and L ^a2 each independently represent -O- or *-O-(CH ₂ ) _k1 -CO-O
k1 represents an integer of 1 to 7, and * represents a bond to --CO--.
R ^a4 and R ^a5 each independently represent a hydrogen atom or a methyl group.
R ^a6 and R ^a7 each independently represent an alkyl group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms, or a combination thereof.
m1 represents an integer of 0 to 14.
n1 represents an integer of 0 to 10.
n1' represents an integer of 0 to 3.

組み合わせた基としては、例えばアルキル基と脂環式炭化水素基とを組み合わせた基が
挙げられる。アルキル基と脂環式炭化水素基とを組み合わせた基としては、例えば、メチ
ルシクロヘキシル基、ジメチルシクロへキシル基、メチルノルボルニル基、シクロヘキシ
ルメチル基、アダマンチルメチル基、アダマンチルジメチル基、ノルボルニルエチル基等
が挙げられる。
Ｒ^ａ６及びＲ^ａ７におけるアルキル基の炭素数は、好ましくは１～６であり、より好ま
しくはメチル基、エチル基又はイソプロピル基である。
Ｒ^ａ６及びＲ^ａ７の脂環式炭化水素基の炭素数は、好ましくは３～８であり、より好ま
しくは３～６である。
アルキル基と脂環式炭化水素基とを組合せた基は、アルキル基と脂環式炭化水素基とを
組合せた合計の炭素数が、１８以下であることが好ましい。
Ｒ^ａ６及びＲ^ａ７は、それぞれ独立に、好ましくは炭素数１～６のアルキル基であり、
より好ましくはメチル基、エチル基又はイソプロピル基であり、さらに好ましくはエチル
基又はイソプロピル基である。
ｍ１は、好ましくは０～３のいずれかの整数であり、より好ましくは０又は１である。
ｎ１は、好ましくは０～３のいずれかの整数であり、より好ましくは０又は１である。
ｎ１’は、好ましくは０～２のいずれかの整数であり、より好ましくは０又は１である
。 R ^a4 and R ^a5 are preferably methyl groups.
L ^a1 and L ^a2 are preferably an oxygen atom or *-O-(CH ₂ ) _k01 -CO-O-
(wherein k01 is preferably an integer of 1 to 4, more preferably 1), and is more preferably an oxygen atom.
Examples of the alkyl group in R ^a6 and R ^a7 include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.
The alicyclic hydrocarbon group for R ^a6 and R ^a7 may be either a monocyclic or polycyclic group.
Examples of the monocyclic alicyclic hydrocarbon group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc. Examples of the polycyclic alicyclic hydrocarbon group include a decahydronaphthyl group, an adamantyl group, a norbornyl group, and the groups shown below (* represents a bond).

Examples of the combined group include a group in which an alkyl group and an alicyclic hydrocarbon group are combined. Examples of the combined group of an alkyl group and an alicyclic hydrocarbon group include a methylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornyl group, a cyclohexylmethyl group, an adamantylmethyl group, an adamantyldimethyl group, and a norbornylethyl group.
The alkyl group for R ^a6 and R ^a7 preferably has 1 to 6 carbon atoms, and is more preferably a methyl group, an ethyl group, or an isopropyl group.
The alicyclic hydrocarbon group of R ^a6 and R ^a7 preferably has 3 to 8 carbon atoms, and more preferably 3 to 6 carbon atoms.
In the group formed by combining an alkyl group and an alicyclic hydrocarbon group, the total number of carbon atoms in the combination of the alkyl group and the alicyclic hydrocarbon group is preferably 18 or less.
R ^a6 and R ^a7 each independently represent an alkyl group having 1 to 6 carbon atoms,
More preferred is a methyl group, an ethyl group, or an isopropyl group, and even more preferred is an ethyl group or an isopropyl group.
m1 is preferably an integer of 0 to 3, and more preferably 0 or 1.
n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.
n1' is preferably an integer of 0 to 2, and more preferably 0 or 1.

Examples of the structural unit (a1-1) include structural units derived from monomers described in JP-A-2010-204646. Among them, the structural units represented by the formulae (a1-1-1) to (a1
-1-4) and a structural unit in which a methyl group corresponding to R ^a4 in the structural unit (a1-1) is replaced with a hydrogen atom, and a structural unit represented by any of the formulas (a1-1-1) to (a1-1-4) is more preferred.

Examples of the structural unit (a1-2) include structural units represented by any one of formulas (a1-2-1) to (a1-2-6) and structural units in which a methyl group corresponding to R ^a5 in the structural unit (a1-2) is replaced with a hydrogen atom, and structural units represented by formulas (a1-2-2), (a1-2-5) and (a1-2-6) are preferred.

The total content of the structural unit (a1-1) and/or the structural unit (a1-2) is usually 10 to 95 mol %, preferably 15 to 80 mol %, more preferably 15 to 75 mol %, and even more preferably 20 to 70 mol %, based on all structural units in the resin (A).
Even more preferably, it is from 25 to 70 mol %.

［式（ａ２－Ａ）中、
Ｒ^a50は、水素原子、ハロゲン原子又はハロゲン原子を有していてもよい炭素数１～６
のアルキル基を表す。
Ｒ^a51は、ハロゲン原子、ヒドロキシ基、炭素数１～６のアルキル基、炭素数１～６の
アルコキシ基、炭素数２～４のアルキルカルボニル基、炭素数２～４のアルキルカルボニ
ルオキシ基、アクリロイルオキシ基又はメタクリロイルオキシ基を表す。
Ａ^a50は、単結合又は^＊－Ｘ^a51－（Ａ^a52－Ｘ^a52）_nb－を表し、＊は－Ｒ^a50が結合す
る炭素原子との結合位を表す。
Ａ^a52は、炭素数１～６のアルカンジイル基を表す。
Ｘ^a51及びＸ^a52は、それぞれ独立に、－Ｏ－、－ＣＯ－Ｏ－又は－Ｏ－ＣＯ－を表す。
ｎｂは、０又は１を表す。
ｍｂは０～４のいずれかの整数を表す。ｍｂが２以上のいずれかの整数である場合、複
数のＲ^a51は互いに同一であっても異なってもよい。］ <Structural Unit (a2-A)>
The structural unit (a2-A) is represented by the following formula:

[In formula (a2-A),
R ^a50 is a hydrogen atom, a halogen atom, or a C 1-6 group which may have a halogen atom.
represents an alkyl group represented by the formula:
R ^a51 represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, 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 position with the carbon atom to which -R ^a50 is bonded.
A ^a52 represents an alkanediyl group having 1 to 6 carbon atoms.
X ^a51 and X ^a52 each independently represent —O—, —CO—O— or —O—CO—.
nb represents 0 or 1.
mb represents an integer of 0 to 4. When mb is an integer of 2 or more, multiple R ^a51 may be the same or different.

Examples of the halogen atom in R ^a50 include a fluorine atom, a chlorine atom, and a bromine atom.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom for 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,
Examples of such groups include a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutyl group, a butyl group, a perfluoropentyl group, a 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl group, and a 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 the alkyl group for R ^a51 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group.
Examples of the alkoxy group for R ^a51 include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, and a tert-butoxy group.
An alkoxy group having 1 to 4 carbon atoms is preferred, a methoxy group or an ethoxy group is more preferred, and a methoxy group is even more preferred.
Examples of the alkylcarbonyl group for R ^a51 include an acetyl group, a propionyl group, and a butyryl group.
The alkylcarbonyloxy group for R ^a51 includes an acetyloxy group, a propionyloxy group, and a butyryloxy group.
R ^a51 is preferably a methyl group.

*-X ^a51 -(A ^a52 -X ^a52 ) _nb - is *-O-, *-CO-O-, *-O-C
O-, *-CO-O-A ^a52 -CO-O-, *-O-CO-A ^a52 -O-, *-O-A ^a52
-CO-O-, *-CO-O-A ^a52 -O-CO-, *-O-CO-A ^a52 -O-CO-,
Among these, *-CO-O-, *-CO-O-A ^a52 -CO-O- or *-
O--A ^a52 --CO--O-- is preferred.

Examples of the alkanediyl group include a methylene group, an ethylene group, and a 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,
Examples of the alkyl group include a 3-diyl group, a 2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group, and a 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-CH ₂ -CO-O-, further preferably a single bond or *-CO-O-.

mb is preferably 0, 1 or 2, more preferably 0 or 1, and particularly preferably 0.
The hydroxy group is preferably bonded to the o- or p-position of the benzene ring, and more preferably to the p-position.

Examples of the structural unit (a2-A) include those described in JP-A-2010-204634 and JP-A-2012-
Examples of structural units include those derived from monomers described in US Pat. No. 5,12577.

Examples of the structural unit (a2-A) include structural units represented by formulae (a2-2-1) to (a2-2-6) and structural units in which a methyl group corresponding to R ^a50 in the structural unit (a2-A) is replaced with a hydrogen atom in the structural units represented by formulae (a2-2-1) to (a2-2-6).
a2-2-1), a structural unit represented by formula (a2-2-3), or a structural unit represented by formula (a
In the structural unit represented by (a2-2-6), a structural unit in which the methyl group corresponding to R ^a50 in the structural unit (a2-A) is replaced with a hydrogen atom is preferred.

The content of the structural unit (a2-A) in the resin (A) is preferably 5% by weight based on the total amount of the structural units.
% to 80 mol %, more preferably 10 to 70 mol %, and even more preferably 15 to
65 mol %, and even more preferably 20 to 65 mol %.
The structural unit (a2-A) can be incorporated into the resin (A) by, for example, polymerizing the structural unit (a1-4) and then treating with an acid such as p-toluenesulfonic acid. Alternatively, the structural unit (a2-A) can be incorporated into the resin (A) by polymerizing the structural unit (a1-4) and then treating with an alkali such as tetramethylammonium hydroxide.

The resin (A) may further contain a structural unit having an acid labile group other than the structural unit (a1-1) and the structural unit (a1-2).

［式（ａ１－０）中、
Ｌ^a01は、－Ｏ－又は^＊－Ｏ－（ＣＨ_２）_ｋ１－ＣＯ－Ｏ－を表し、ｋ１は１～７のい
ずれかの整数を表し、＊は－ＣＯ－との結合手を表す。
Ｒ^a01は、水素原子又はメチル基を表す。
Ｒ^a02、Ｒ^a03及びＲ^a04は、それぞれ独立に、炭素数１～８のアルキル基、炭素数３～
１８の脂環式炭化水素基又はこれらを組み合わせた基を表す。］ Examples of structural units having an acid labile group other than the structural unit (a1-1) and the structural unit (a1-2) include a structural unit represented by formula (a1-0) (hereinafter, sometimes referred to as structural unit (a1-0)). These may be used alone or in combination of two or more kinds.

[In formula (a1-0),
L ^a01 represents --O-- or ^* -O--(CH ₂ ) _k1 --CO--O--, where k1 represents an integer of 1 to 7, and * represents a bond to --CO--.
R ^a01 represents a hydrogen atom or a methyl group.
R ^a02 , R ^a03 and R ^a04 each independently represent an alkyl group having 1 to 8 carbon atoms,
18 alicyclic hydrocarbon groups or combinations thereof.]

アルキル基と脂環式炭化水素基とを組み合わせた基としては、例えば、メチルシクロヘ
キシル基、ジメチルシクロへキシル基、メチルノルボルニル基、シクロヘキシルメチル基
、アダマンチルメチル基、アダマンチルジメチル基、ノルボルニルエチル基等が挙げられ
る。
Ｒ^a02、Ｒ^a03及びＲ^a04の脂環式炭化水素基の炭素数は、好ましくは３～８であり、よ
り好ましくは３～６である。
アルキル基と脂環式炭化水素基とを組合せた基は、これらアルキル基と脂環式炭化水素
基とを組合せた合計炭素数が、１８以下であることが好ましい。
Ｒ^a02及びＲ^a03は、好ましくは炭素数１～６のアルキル基であり、より好ましくはメチ
ル基又はエチル基である。
Ｒ^a04は、好ましくは炭素数１～６のアルキル基又は炭素数５～１２の脂環式炭化水素
基であり、より好ましくはメチル基、エチル基、シクロヘキシル基又はアダマンチル基で
ある。 R ^a01 is preferably a methyl group.
L ^a01 is preferably an oxygen atom or *-O-(CH ₂ ) _k01 -CO-O- (wherein k01 is preferably an integer of 1 to 4, more preferably 1), and is more preferably an oxygen atom.
The alkyl group of R ^a02 , R ^a03 and R ^a04 is preferably a methyl group, an ethyl group, a propyl group,
Examples of the alkyl group include an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, and an n-octyl group.
The alicyclic hydrocarbon group of R ^a02 , R ^a03 and R ^a04 may be either a monocyclic or polycyclic group.
Examples of the monocyclic alicyclic hydrocarbon group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic alicyclic hydrocarbon group include a decahydronaphthyl group, an adamantyl group, a norbornyl group, and the following groups (*
represents a bond.) The alicyclic hydrocarbon group of ^{R a02} , R ^a03 and R ^a04 preferably has 3 to 16 carbon atoms.

Examples of the group combining an alkyl group with an alicyclic hydrocarbon group include a methylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornyl group, a cyclohexylmethyl group, an adamantylmethyl group, an adamantyldimethyl group, and a norbornylethyl group.
The alicyclic hydrocarbon group of R ^a02 , R ^a03 and R ^a04 preferably has 3 to 8 carbon atoms, and more preferably 3 to 6 carbon atoms.
In the group in which an alkyl group and an alicyclic hydrocarbon group are combined, the total number of carbon atoms in the combination of the alkyl group and the alicyclic hydrocarbon group is preferably 18 or less.
R ^a02 and R ^a03 are preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group.
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.

Examples of the structural unit (a1-0) include those represented by the formulae (a1-0-1) to (a1-0-12):
and a structural unit in which a methyl group corresponding to R ^a01 is replaced with a hydrogen atom, and a structural unit represented by any of formulae (a1-0-1) to (a1-0-10) is preferred.

［式（ａ１－４）中、
Ｒ^a32は、水素原子、ハロゲン原子、又は、ハロゲン原子を有していてもよい炭素数１
～６のアルキル基を表す。
Ｒ^a33は、ハロゲン原子、ヒドロキシ基、炭素数１～６のアルキル基、炭素数１～６の
アルコキシ基、炭素数２～４のアルキルカルボニル基、炭素数２～４のアルキルカルボニ
ルオキシ基、アクリロイルオキシ基又はメタクリロイルオキシ基を表す。
ｌａは０～４のいずれかの整数を表す。ｌａが２以上である場合、複数のＲ^a33は互い
に同一であっても異なってもよい。
Ｒ^a34及びＲ^a35はそれぞれ独立に、水素原子又は炭素数１～１２の炭化水素基を表し、
Ｒ^a36は、炭素数１～２０の炭化水素基を表すか、Ｒ^a35及びＲ^a36は互いに結合してそれ
らが結合する－Ｃ－Ｏ－とともに炭素数２～２０の２価の炭化水素基を形成し、該炭化水
素基及び該２価の炭化水素基に含まれる－ＣＨ₂－は、－Ｏ－又は－Ｓ－で置き換わって
もよい。］ When the resin (A) contains the structural unit (a1-0), the content thereof is usually 5 to 60 mol %, preferably 5 to 50 mol %, and more preferably 10 to 40 mol %, based on all structural units in the resin (A).
An example of a structural unit having an acid labile group other than the structural unit (a1-1) and the structural unit (a1-2) is a structural unit represented by formula (a1-4) (hereinafter, sometimes referred to as "structural unit (a1-4)").

[In formula (a1-4),
R ^a32 is a hydrogen atom, a halogen atom, or a C1 alkyl group which may have a halogen atom.
represents an alkyl group having a molecular weight of 1 to 6;
R ^a33 represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, an acryloyloxy group or a methacryloyloxy group.
la represents an integer of 0 to 4. When la is 2 or more, multiple R ^a33 may be the same or different.
R ^a34 and R ^a35 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms;
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 -CH ₂ - contained in the hydrocarbon group and the divalent hydrocarbon group may be replaced by -O- or -S-.]

Examples of the alkyl group in R ^a32 and R ^a33 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, and a hexyl group, etc. The alkyl group is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group, and even more preferably a methyl group.
Examples of the halogen atom in R ^a32 and R ^a33 include a fluorine atom, a chlorine atom, and a bromine atom.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom include a trifluoromethyl group, a difluoromethyl group, a methyl group, a perfluoroethyl group, a 2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethyl group, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, a propyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutyl group, a butyl group, a perfluoropentyl group, a 2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl group, and a perfluorohexyl group.

Examples of the alkoxy group in R ^a33 include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, and a hexyloxy group.
An alkoxy group represented by formula 4 is preferred, a methoxy group or an ethoxy group is more preferred, and a methoxy group is even more preferred.
Alkylcarbonyl groups include acetyl, propionyl and butyryl groups.
Examples of the alkylcarbonyloxy group include an acetyloxy group, a propionyloxy group, and a butyryloxy group.

芳香族炭化水素基としては、フェニル基、ナフチル基、アントリル基、ｐ－メチルフェ
ニル基、ｐ－ｔｅｒｔ－ブチルフェニル基、ｐ－アダマンチルフェニル基、トリル基、キ
シリル基、クメニル基、メシチル基、ビフェニル基、フェナントリル基、２，６－ジエチ
ルフェニル基、２－メチル－６－エチルフェニル基等のアリール基等が挙げられる。
組み合わせた基としては、上述したアルキル基と脂環式炭化水素基とを組み合わせた基
（例えばアルキルシクロアルキル基、及びシクロアルキルアルキル基等が挙げられる。）
、ベンジル基等のアラルキル基、フェニルシクロヘキシル基等のアリール－シクロヘキシ
ル基等が挙げられる。特に、Ｒ^a36としては、炭素数１～１８のアルキル基、炭素数３～
１８の脂環式炭化水素基、炭素数６～１８の芳香族炭化水素基又はこれらを組み合わせる
ことにより形成される基が挙げられる。
特に、Ｒ^a36としては、炭素数１～１８のアルキル基、炭素数３～１８の脂環式炭化水
素基、炭素数６～１８の芳香族炭化水素基又はこれらを組み合わせることにより形成され
る基が挙げられる。 The hydrocarbon group for R ^a34 , R ^a35 and R ^a36 includes an alkyl group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group.
The alicyclic hydrocarbon group may be either monocyclic or polycyclic. Examples of the monocyclic alicyclic hydrocarbon group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic alicyclic hydrocarbon group include a decahydronaphthyl group, an adamantyl group, a norbornyl group, and the following groups (* represents a bond). The number of carbon atoms in the alicyclic hydrocarbon groups of ^{R a1} to R ^a3 is preferably 3 to 16.

Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group, a naphthyl group, an anthryl group, a p-methylphenyl group, a p-tert-butylphenyl group, a p-adamantylphenyl group, a tolyl group, a xylyl group, a cumenyl group, a mesityl group, a biphenyl group, a phenanthryl group, a 2,6-diethylphenyl group, and a 2-methyl-6-ethylphenyl group.
The combined group includes a group in which the above-mentioned alkyl group and alicyclic hydrocarbon group are combined (for example, an alkylcycloalkyl group, a cycloalkylalkyl group, etc.).
R ^a36 is preferably an alkyl group having 1 to 18 carbon atoms, an aralkyl group such as a benzyl group, an aryl-cyclohexyl group such as a phenylcyclohexyl group, or the like.
Examples of the alkyl group include an alicyclic hydrocarbon group having from 1 to 18 carbon atoms, an aromatic hydrocarbon group having from 6 to 18 carbon atoms, and a group formed by combining these groups.
In particular, R ^a36 may be 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 combining these.

In formula (a1-4), R ^a32 is preferably a hydrogen atom.
R ^a33 is preferably an alkoxy group having 1 to 4 carbon atoms, more preferably a methoxy group or an ethoxy group, and even more preferably a methoxy group.
As la, 0 or 1 is preferable, and 0 is more preferable.
R ^a34 is preferably a hydrogen atom.
R ^a35 is preferably an alkyl group or an alicyclic hydrocarbon group having 1 to 12 carbon atoms, 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 combining these, and more 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 combining these.
The alkyl group and the alicyclic hydrocarbon group for R ^a36 are preferably unsubstituted. The aromatic hydrocarbon group for ^{R a36} is preferably an aromatic ring having an aryloxy group having 6 to 10 carbon atoms.

The --OC(R ^a34 )(R ^a35 )--O--R ^a36 in the structural unit (a1-4) is eliminated on contact with an acid (eg, p-toluenesulfonic acid) to form a hydroxy group.

Examples of the structural unit (a1-4) include structural units derived from monomers described in JP-A-2010-204646.
-4-12) and a structural unit in which a hydrogen atom corresponding to R ^a32 is replaced with a methyl group, and more preferably, the structural units represented by the formulas (a1-4-1) to (a1-4
-5), and structural units represented by formula (a1-4-10).

When resin (A) contains the structural unit (a1-4), the content thereof is preferably 5 to 60 mol %, more preferably 5 to 50 mol %, and even more preferably 10 to 40 mol %, based on the total of all structural units in resin (A).

［式（ａ１－５）中、
Ｒ^a8は、ハロゲン原子を有していてもよい炭素数１～６のアルキル基、水素原子又はハ
ロゲン原子を表す。
Ｚ^a1は、単結合又は＊－（ＣＨ₂）_h3－ＣＯ－Ｌ⁵⁴－を表し、ｈ３は１～４のいずれか
の整数を表し、＊は、Ｌ⁵¹との結合手を表す。
Ｌ⁵¹、Ｌ⁵²、Ｌ⁵³及びＬ⁵⁴は、それぞれ独立に、－Ｏ－又は－Ｓ－を表す。
ｓ１は、１～３のいずれかの整数を表す。
ｓ１’は、０～３のいずれかの整数を表す。］ Examples of structural units having an acid labile group other than the structural unit (a1-1) and the structural unit (a1-2) include a structural unit represented by formula (a1-5) (hereinafter sometimes referred to as "structural unit (a1-5)").

[In formula (a1-5),
R ^a8 represents an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom.
Z ^a1 represents a single bond or *-(CH ₂ ) _h3 -CO-L ⁵⁴ -, h3 represents an integer of 1 to 4, and * represents a bond to L ⁵¹ .
L ⁵¹ , L ⁵² , L ⁵³ and L ⁵⁴ each independently represent --O-- or --S--.
s1 represents an integer of 1 to 3.
s1′ represents an integer of 0 to 3.]

Examples of the halogen atom include a fluorine atom and a chlorine atom, with a fluorine atom being preferred.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a fluoromethyl group, and a trifluoromethyl group.
In formula (a1-5), R ^a8 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--.
It is preferable that s1 is 1.
s1' is preferably an integer of 0 to 2.
Z ^a1 is preferably a single bond or *--CH ₂ --CO--O--.

Examples of the structural unit (a1-5) include structural units derived from monomers described in JP-A-2010-61117.
4), and the structural units represented by the formula (a1-5-1) or the formula (a1-5-2) are preferred.
) is more preferred.

When the resin (A) contains the structural unit (a1-5), the content thereof is preferably from 1 to 50 mol %, more preferably from 3 to 45 mol %, and even more preferably from 5 to 40 mol %, based on all structural units in the resin (A).

［式（ａ１－０Ｘ）中、
Ｒ^ｘ１は、水素原子又はメチル基を表す。
Ｒ^ｘ２及びＲ^ｘ３は、それぞれ独立に、炭素数１～６の飽和炭化水素基を表す。
Ａｒ^ｘ１は、炭素数６～３６の芳香族炭化水素基を表す。］ Examples of structural units having an acid labile group other than the structural unit (a1-1) and the structural unit (a1-2) include structural units represented by the formula (a1-0X) (hereinafter, structural unit (a1-0X)
Two or more types of structural units (a1-0X) may be selected and added to the resin (A).

[In formula (a1-0X),
R ^x1 represents a hydrogen atom or a methyl group.
R ^x2 and R ^x3 each independently represent a saturated hydrocarbon group having 1 to 6 carbon atoms.
Ar ^x1 represents an aromatic hydrocarbon group having 6 to 36 carbon atoms.]

The saturated hydrocarbon group for R ^x2 and R ^x3 includes an alkyl group, an alicyclic hydrocarbon group, and a group formed by combining these.
Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group.
The alicyclic hydrocarbon group may be either monocyclic or polycyclic, and examples of the monocyclic alicyclic hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

Examples of the aromatic hydrocarbon group for Ar ^x1 include aryl groups having 6 to 36 carbon atoms, such as a phenyl group, a naphthyl group, and an anthryl group.
The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 1
8, and more preferably a phenyl group.

Ar ^x1 is preferably an aromatic hydrocarbon group having 6 to 18 carbon atoms, more preferably a phenyl group or naphthyl group, and even more preferably a phenyl group.
R ^x1 , R ^x2 and R ^x3 are each preferably independently a methyl group or an ethyl group, and more preferably a methyl group.

Ｒ^ｘ１に相当するメチル基が水素原子に置き換わった化合物も、構造単位（ａ１－０Ｘ
）の具体例として挙げることができる。 Examples of the structural unit (a1-0X) include the structural units shown below.
Preferably, the structural unit (a1-0X) is the structural unit (a1-0X-1) to the structural unit (a1-0X-3).

A compound in which the methyl group corresponding to R ^x1 is replaced with a hydrogen atom also has the structural unit (a1-0X
) can be cited as a specific example.

When the resin (A) contains the structural unit (a1-0X), the content thereof is preferably 5 to 60 mol %, more preferably 5 to 50 mol %, and even more preferably 10 to 40 mol %, based on all monomers in the resin (A).
The resin (A) may contain two or more types of the structural unit (a1-0X).

Further, examples of structural units having an acid labile group other than the structural unit (a1-1) and the structural unit (a1-2) include structural units represented by the following formulae (a1-3-1) to (a1-3-7).

When resin (A) contains any of the structural units represented by formulae (a1-3-1) to (a1-3-7), the content thereof is preferably 5 to 60 mol %, more preferably 5 to 50 mol %, and still more preferably 10 to 40 mol %, based on all structural units of resin (A).

Resin (A) may further contain a structural unit (hereinafter may be referred to as "structural unit (s)") derived from a monomer other than the structural unit (a2-A) that does not have a halogen atom and does not have an acid labile group (hereinafter may be referred to as "monomer (s)"), a structural unit other than the structural unit (s), for example, a structural unit that has a halogen atom (hereinafter may be referred to as "structural unit (a4)"), a structural unit that does not have a halogen atom and has a non-leaving hydrocarbon group (hereinafter may be referred to as "structural unit (a5)"), and/or a structural unit derived from other monomers known in the field.

<Structural unit (s)>
The structural unit (s) is derived from a monomer having no acid labile group (hereinafter, may be referred to as "monomer (s)"). As the monomer from which the structural unit (s) is derived, a monomer having no acid labile group known in the resist field can be used.
The structural unit (s) preferably has a hydroxy group or a lactone ring. By using a resin having a structural unit having a hydroxy group and no acid labile group (hereinafter sometimes referred to as "structural unit (a2)") and/or a structural unit having a lactone ring and no acid labile group (hereinafter sometimes referred to as "structural unit (a3)") in the resist composition of the present invention, the resolution of the resist pattern and adhesion to the substrate can be improved.

<Structural unit (a2)>
The hydroxy group contained in the structural unit (a2) may be an alcoholic hydroxy group or a phenolic hydroxy group.
When a resist pattern is produced from the resist composition of the present invention, the exposure light source is KrF
When a high-energy ray such as an excimer laser (248 nm), an electron beam, or EUV (extreme ultraviolet light) is used, the structural unit (a2) may be a structural unit having a phenolic hydroxy group (
In addition, when an ArF excimer laser (193 nm) or the like is used, it is preferable to use a structural unit (a2) having an alcoholic hydroxyl group as the structural unit (a2).
) is preferable, and it is more preferable to use the structural unit (a2-1) described below.
As a2), one type may be contained alone, or two or more types may be contained.

式（ａ２－１）中、
Ｌ^a3は、－Ｏ－又は＊－Ｏ－（ＣＨ₂）_k2－ＣＯ－Ｏ－を表し、
ｋ２は１～７のいずれかの整数を表す。＊は－ＣＯ－との結合部位を表す。
Ｒ^a14は、水素原子又はメチル基を表す。
Ｒ^a15及びＲ^a16は、それぞれ独立に、水素原子、メチル基又はヒドロキシ基を表す。
ｏ１は、０～１０のいずれかの整数を表す。 As the structural unit (a2) having an alcoholic hydroxy group, the structural unit represented by the formula (a2) may be
a2-1) (hereinafter may be referred to as “structural unit (a2-1)”).

In formula (a2-1),
L ^a3 represents —O— or *—O—(CH ₂ ) _k2 —CO—O—;
k2 represents an integer of 1 to 7. * represents a bonding 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 hydroxy group.
o1 represents an integer of 0 to 10.

In formula (a2-1), L ^a3 is preferably —O—, —O—(CH ₂ ) _f1 —CO—O—
(wherein f1 represents an integer of 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 hydroxy group.
o1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

Examples of the structural unit (a2-1) include structural units derived from monomers described in JP-A-2010-204646.
), and the structural unit represented by any one of the formulas (a2-1-1) to (a2-1-4) is preferred.
A structural unit represented by any one of the formulas (a2-1-1) or (a2-1-
The structural unit represented by 3) is more preferred.

When the resin (A) contains the structural unit (a2-1), the content thereof is usually 1 to 45 mol %, preferably 1 to 40 mol %, more preferably 1 to 35 mol %, and even more preferably 2 to 20 mol %, based on all structural units of the resin (A).

<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 may be a condensed ring of a monocyclic lactone ring with another ring.
-Bridged ring containing a butyrolactone ring structure (for example, a structural unit represented by the following formula (a3-2))
Examples include:

［式（ａ３－１）、式（ａ３－２）、式（ａ３－３）及び式（ａ３－４）中、
Ｌ^ａ４、Ｌ^ａ５及びＬ^ａ６は、それぞれ独立に、－Ｏ－又は＊－Ｏ－（ＣＨ_２）_ｋ３－
ＣＯ－Ｏ－（ｋ３は１～７のいずれかの整数を表す。）で表される基を表す。
Ｌ^ａ７は、－Ｏ－、＊－Ｏ－Ｌ^ａ８－Ｏ－、＊－Ｏ－Ｌ^ａ８－ＣＯ－Ｏ－、＊－Ｏ－Ｌ
^ａ８－ＣＯ－Ｏ－Ｌ^ａ９－ＣＯ－Ｏ－又は＊－Ｏ－Ｌ^ａ８－Ｏ－ＣＯ－Ｌ^ａ９－Ｏ－を表
す。
Ｌ^ａ８及びＬ^ａ９は、それぞれ独立に、炭素数１～６のアルカンジイル基を表す。
＊はカルボニル基との結合部位を表す。
Ｒ^ａ１８、Ｒ^ａ１９及びＲ^ａ２０は、それぞれ独立に、水素原子又はメチル基を表す。
Ｒ^ａ２４は、ハロゲン原子を有していてもよい炭素数１～６のアルキル基、水素原子又
はハロゲン原子を表す。
Ｘ^ａ３は、－ＣＨ_２－又は酸素原子を表す。
Ｒ^ａ２１は炭素数１～４の脂肪族炭化水素基を表す。
Ｒ^ａ２２、Ｒ^ａ２３及びＲ^ａ２５は、それぞれ独立に、カルボキシ基、シアノ基又は炭
素数１～４の脂肪族炭化水素基を表す。
ｐ１は０～５のいずれかの整数を表す。
ｑ１は、０～３のいずれかの整数を表す。
ｒ１は、０～３のいずれかの整数を表す。
ｗ１は、０～８のいずれかの整数を表す。
ｐ１、ｑ１、ｒ１及び／又はｗ１が２以上のとき、複数のＲ^ａ２１、Ｒ^ａ２２、Ｒ^ａ２
３及び／又はＲ^ａ２５は互いに同一でも異なっていてもよい。］ The structural unit (a3) is preferably represented by the formula (a3-1), the formula (a3-2), or the formula (a3-3):
or a structural unit represented by formula (a3-4).
Two or more kinds may be contained.

[In formula (a3-1), formula (a3-2), formula (a3-3) and formula (a3-4),
L ^a4 , L ^a5 and L ^a6 each independently represent —O— or *—O—(CH ₂ ) _k3 —.
It represents a group represented by CO-O- (k3 represents an integer of 1 to 7).
L ^a7 is -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 the bonding site with the carbonyl group.
R ^a18 , R ^a19 and R ^a20 each independently represent a hydrogen atom or a methyl group.
R ^a24 represents an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, a hydrogen atom or a halogen atom.
X ^a3 represents —CH ₂ — or an oxygen atom.
R ^a21 represents an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
R ^a22 , R ^a23 and R ^a25 each independently represent a carboxy group, a cyano group or an aliphatic hydrocarbon group having 1 to 4 carbon atoms.
p1 represents an integer of 0 to 5.
q1 represents an integer of 0 to 3.
r1 represents an integer of 0 to 3.
w1 represents an integer of 0 to 8.
When p1, q1, r1 and/or w1 are 2 or more, a plurality of R ^a21 , R ^a22 , R ^a2
3 and/or R ^a25 may be the same or different.

Examples of the aliphatic hydrocarbon group for R ^a21 , R ^a22 , R ^a23 and R ^a25 include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group and a tert-butyl group.
The halogen atom in R ^a24 includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
Examples of the alkyl group for R ^a24 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. Of these, an alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.
Examples of the alkyl group having a halogen atom for R ^a24 include a trifluoromethyl group,
Examples of such groups include a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, a perfluorohexyl group, a trichloromethyl group, a tribromomethyl group, and a triiodomethyl group.

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

In formulae (a3-1) to (a3-3), L ^a4 to L ^a6 each independently represent preferably —O— or *-O-(CH ₂ ) _k3 -CO-O-, where k3 is an integer from 1 to 4, more preferably —O— and *-O-CH ₂ -CO-O-, and still more preferably an oxygen atom.
R ^a18 to R ^a21 are preferably methyl groups.
R ^a22 and R ^a23 each independently preferably represent a carboxy group, a cyano group, or a methyl group.
p1, q1 and r1 each independently represent an integer of preferably 0 to 2;
More preferably, it is 0 or 1.

（式中、Ｒ^ａ２４、Ｌ^ａ７は、上記と同じ意味を表す。） 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.
R ^a25 is preferably a carboxy group, a cyano group or a methyl group.
L ^a7 is preferably —O— or *-OL ^a8 —CO—O—, and more preferably —O—, —O—CH ₂ —CO—O— or —O—C ₂ H ₄ —CO—O—.
w1 is preferably an integer of 0 to 2, and more preferably 0 or 1.
In particular, the formula (a3-4) is preferably the formula (a3-4)'.

(In the formula, R ^a24 and L ^a7 have the same meanings as above.)

Examples of the structural unit (a3) include monomers described in JP-A-2010-204646, monomers described in JP-A-2000-122294, and monomers described in JP-A-2012-41274.
Examples of the structural unit (a3) include structural units derived from monomers described in the above publication.
, Formula (a3-3-1), Formula (a3-3-2) and Formula (a3-4-1) to Formula (a3-4-1)
2), and in the structural unit, the structural unit represented by the formula (a3-1) to the formula (a3-2)
In a3-4), preferred are structural units in which the methyl groups corresponding to R ^a18 , R ^a19 , R ^a20 and R ^a24 are replaced by hydrogen atoms.

When the resin (A) contains the structural unit (a3), the total content thereof is usually 5 to 70 mol %, preferably 10 to 65 mol %, and more preferably 10 to 60 mol %, based on all structural units in the resin (A).
Furthermore, the content of the structural unit (a3-1), the structural unit (a3-2), the structural unit (a3-3) or the structural unit (a3-4) is preferably 5 to 60 mol %, more preferably 5 to 50 mol %, and even more preferably 10 to 50 mol %, based on the total structural units of the resin (A).

［式（ａ４）中、
Ｒ⁴¹は、水素原子又はメチル基を表す。
Ｒ⁴²は、炭素数１～２４のハロゲン原子を有する飽和炭化水素基を表し、該飽和炭化水
素基に含まれる－ＣＨ₂－は、－Ｏ－又は－ＣＯに置き換わっていてもよい。］
Ｒ⁴²で表される飽和炭化水素基は、鎖式飽和炭化水素基及び単環又は多環の脂環式飽和
炭化水素基、並びに、これらを組み合わせることにより形成される基等が挙げられる。 <Structural unit (a4)>
Examples of the structural unit (a4) include the following structural units.

[In formula (a4),
^R41 represents a hydrogen atom or a methyl group.
R ⁴² represents a saturated hydrocarbon group having 1 to 24 carbon atoms and containing a halogen atom, and --CH ₂ -- contained in the saturated hydrocarbon group may be replaced by --O-- or --CO.]
Examples of the saturated hydrocarbon group represented by R ⁴² include chain saturated hydrocarbon groups, monocyclic or polycyclic alicyclic saturated hydrocarbon groups, and groups formed by combining these groups.

組み合わせにより形成される基としては、１以上のアルキル基又は１以上のアルカンジ
イル基と、１以上の脂環式飽和炭化水素基とを組み合わせることにより形成される基が挙
げられ、－アルカンジイル基－脂環式飽和炭化水素基、－脂環式飽和炭化水素基－アルキ
ル基、－アルカンジイル基－脂環式飽和炭化水素基－アルキル基等が挙げられる。 Examples of the chain saturated hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, a dodecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.
Examples of the monocyclic or polycyclic alicyclic saturated hydrocarbon group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group; a decahydronaphthyl group,
Examples of the aromatic ring include polycyclic and alicyclic saturated hydrocarbon groups such as an adamantyl group, a norbornyl group, and the following groups (* represents a bonding site):

Examples of groups formed by combination 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.

［式（ａ４－０）中、
Ｒ⁵⁴は、水素原子又はメチル基を表す。
Ｌ^4ａは、単結合又は炭素数１～４のアルカンジイル基を表す。
Ｌ^3ａは、炭素数１～８のペルフルオロアルカンジイル基又は炭素数３～１２のペルフ
ルオロシクロアルカンジイル基を表す。
Ｒ⁶⁴は、水素原子又はフッ素原子を表す。］ Examples of the structural unit (a4) include a structural unit represented by formula (a4-0), a structural unit represented by formula (a4-1), and a 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.

The alkanediyl group in ^L4a is a methylene group, an ethylene group, a propane-1,
linear alkanediyl groups such as butane-1,4-diyl group, ethane-1,1
Examples of branched alkanediyl groups include a 1,2-diyl group, a propane-1,2-diyl group, a butane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, and a 2-methylpropane-1,2-diyl group.

The perfluoroalkanediyl group in ^L3a includes a difluoromethylene group, a perfluoroethylene group, a perfluoropropane-1,1-diyl group, a perfluoropropane-1,3-diyl group, a perfluoropropane-1,2-diyl group, a perfluoropropane-2,2-diyl group, a perfluorobutane-1,4-diyl group, a perfluorobutane-2,3-diyl group, a perfluorobutane-3,4-diyl group, a perfluorobutane-4,5-diyl group, a perfluorobutane-5,6-diyl group, a perfluorobutane-6,7-diyl group, a perfluorobutane-7,8-diyl group, a perfluorobutane-8,9-diyl group, a perfluorobutane-9,10-diyl group, a perfluorobutane-10,11-diyl group, a perfluorobutane-11,12-diyl group, a perfluorobutane-12,2-diyl group
,2-diyl group, perfluorobutane-1,2-diyl group, perfluoropentane-1,
5-diyl group, perfluoropentane-2,2-diyl group, perfluoropentane-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, perfluorooctane-4,4-diyl group, and the like.
Examples of the perfluorocycloalkanediyl group in ^L3a include a perfluorocyclohexanediyl group, a perfluorocyclopentanediyl group, a perfluorocycloheptanediyl group, and a 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.
L ^3a is preferably a perfluoroalkanediyl group having 1 to 6 carbon atoms, and more preferably a perfluoroalkanediyl group having 1 to 3 carbon atoms.

The structural unit (a4-0) may be any of the structural units shown below and the structural units (
a4-0) is a structural unit in which a methyl group corresponding to R ⁵⁴ is replaced with a hydrogen atom.

［式（ａ４－１）中、
Ｒ^a41は、水素原子又はメチル基を表す。
Ｒ^a42は、置換基を有していてもよい炭素数１～２０の飽和炭化水素基を表し、該飽和
炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ａ^a41は、置換基を有していてもよい炭素数１～６のアルカンジイル基又は式（ａ－ｇ
１）で表される基を表す。ただし、Ａ^ａ４１及びＲ^ａ４２のうち少なくとも１つは、置換
基としてハロゲン原子（好ましくはフッ素原子）を有する。

〔式（ａ－ｇ１）中、
ｓは０又は１を表す。
Ａ^a42及びＡ^a44は、それぞれ独立に、置換基を有していてもよい炭素数１～５の２価の
飽和炭化水素基を表す。
Ａ^a43は、単結合又は置換基を有していてもよい炭素数１～５の２価の飽和炭化水素基
を表す。
Ｘ^a41及びＸ^a42は、それぞれ独立に、－Ｏ－、－ＣＯ－、－ＣＯ－Ｏ－又は－Ｏ－ＣＯ
－を表す。
ただし、Ａ^a42、Ａ^a43、Ａ^a44、Ｘ^a41及びＸ^a42の炭素数の合計は７以下である。〕
＊は結合部位であり、右側の＊が－Ｏ－ＣＯ－Ｒ^a42との結合部位である。］

[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 a substituent, and --CH ₂ -- contained in the saturated hydrocarbon group is replaced by --O-- or --CO--. This is also fine.
A ^a41 is a C1-6 alkanediyl group which may have a substituent or a group represented by the formula (a-g
1), provided that 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 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 a substituent.
A ^a43 represents a single bond or a divalent saturated hydrocarbon group having 1 to 5 carbon atoms which may have a substituent.
X ^a41 and X ^a42 each independently represent -O-, -CO-, -CO-O- or -O-CO
Represents -.
However, the total number of carbon atoms of A ^a42 , A ^a43 , A ^a44 , X ^a41 and X ^a42 is 7 or less.
* indicates a binding site, and the * on the right side is the binding site with -O-CO-R ^a42 .]

Examples of the saturated hydrocarbon group for R ^a42 include chain saturated hydrocarbon groups, monocyclic or polycyclic saturated alicyclic hydrocarbon groups, and groups formed by combining these.

組み合わせにより形成される基としては、１以上のアルキル基又は１以上のアルカンジ
イル基と、１以上の飽和脂環式炭化水素基とを組み合わせることにより形成される基が挙
げられ、－アルカンジイル基－飽和脂環式炭化水素基、－飽和脂環式炭化水素基－アルキ
ル基、－アルカンジイル基－飽和脂環式炭化水素基－アルキル基等が挙げられる。 Examples of the chain saturated hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, a dodecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.
Examples of the monocyclic or polycyclic saturated alicyclic hydrocarbon group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group; a decahydronaphthyl group,
Examples of the groups include polycyclic and alicyclic hydrocarbon groups such as an adamantyl group, a norbornyl group, and the following groups (* represents a bond):

Examples of groups formed by combination include groups formed by combining one or more alkyl groups or one or more alkanediyl groups with one or more saturated alicyclic hydrocarbon groups, such as -alkanediyl group-saturated alicyclic hydrocarbon group, -saturated alicyclic hydrocarbon group-alkyl group, and -alkanediyl group-saturated alicyclic hydrocarbon group-alkyl group.

［式（ａ－ｇ３）中、
Ｘ^a43は、酸素原子、カルボニル基、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊は
Ｒ^a42との結合部位を表す。）。
Ａ^a45は、ハロゲン原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
＊は結合部位を表す。］
ただし、Ｒ^a42－Ｘ^a43－Ａ^a45において、Ｒ^a42がハロゲン原子を有しない場合は、Ａ^a4
5は、少なくとも１つのハロゲン原子を有する炭素数１～１７の飽和炭化水素基を表す。 Examples of the substituent that R ^a42 may have include at least one selected from the group consisting of a halogen atom and a group represented by formula (a-g3). Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable.

[In formula (a-g3),
X ^a43 represents an oxygen atom, a carbonyl group, *-O-CO- or *-CO-O- (* represents the bonding site to R ^a42 ).
A ^a45 represents a saturated hydrocarbon group having 1 to 17 carbon atoms which may have a halogen atom.
* indicates a binding site.]
However, in R ^a42 -X ^a43 -A ^a45 , when R ^a42 does not have a halogen atom, A ^a4
5 represents a saturated hydrocarbon group having 1 to 17 carbon atoms and containing at least one halogen atom.

組み合わせにより形成される基としては、１以上のアルキル基又は１以上のアルカンジ
イル基と、１以上の脂環式炭化水素基とを組み合わせることにより形成される基が挙げら
れ、－アルカンジイル基－脂環式炭化水素基、－脂環式炭化水素基－アルキル基、－アル
カンジイル基－脂環式炭化水素基－アルキル基等が挙げられる。 Examples of the saturated hydrocarbon group for A ^a45 include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl; monocyclic alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; and polycyclic alicyclic hydrocarbon groups such as decahydronaphthyl, adamantyl, norbornyl, and the following groups (* represents a bond):

Examples of groups formed by combination 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 having 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, still 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 a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluoroheptyl group, and a perfluorooctyl group. Examples of perfluorocycloalkyl groups include a 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.
The number is preferably one.

［式（ａ－ｇ２）中、
Ａ^a46は、ハロゲン原子を有していてもよい炭素数１～１７の２価の飽和炭化水素基を
表す。
Ｘ^a44は、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＡ^a46との結合部位を表す。
）。
Ａ^a47は、ハロゲン原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
ただし、Ａ^a46、Ａ^a47及びＸ^a44の炭素数の合計は１８以下であり、Ａ^a46及びＡ^a47の
うち、少なくとも一方は、少なくとも１つのハロゲン原子を有する。
＊はカルボニル基との結合部位を表す。］ When R ^a42 is a saturated hydrocarbon group having a group represented by formula (a-g3), 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 have a halogen atom.
X ^a44 represents *-O-CO- or *-CO-O- (* represents the bonding site with A ^a46 .
).
A ^a47 represents a saturated hydrocarbon group having 1 to 17 carbon atoms which may have a halogen atom.
However, the total number of carbon atoms of 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 divalent saturated hydrocarbon group for A ^a46 preferably has 1 to 6 carbon atoms, and more preferably has 1 to 3 carbon atoms.
The saturated hydrocarbon group of A ^a47 preferably has 4 to 15 carbon atoms, more preferably 5 to 12 carbon ^atoms .
More preferably, ⁴⁷ is a cyclohexyl group or an adamantyl group.

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

The alkanediyl group in A ^a41 is a methylene group, an ethylene group, a propane-1,
3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1
linear alkanediyl groups such as propane-1,2-diyl group, butane-1,6-diyl group, etc.
,3-diyl group, 2-methylpropane-1,2-diyl group, 1-methylbutane-1,4-
and branched alkanediyl groups such as diyl group and 2-methylbutane-1,4-diyl group.
The substituent in the alkanediyl group represented by A ^a41 is a hydroxy group or an alkanediyl group having 1 to 10 carbon atoms.
6 alkoxy groups and the like.
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 the divalent saturated hydrocarbon group represented by A ^a42 , A ^a43 and A ^a44 in the group represented by formula (a-g1) include linear or branched alkanediyl groups, monocyclic divalent alicyclic saturated hydrocarbon groups, and groups formed by combining alkanediyl groups and divalent alicyclic saturated hydrocarbon groups. Specific examples include a methylene group, an ethylene group, a propane-1
,3-diyl group, propane-1,2-diyl group, butane-1,4-diyl group, 1-methylpropane-1,3-diyl group, 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, and the like.
Examples of the substituent of the divalent saturated hydrocarbon group represented by A ^a42 , A ^a43 and A ^a44 include a hydroxy group and an alkoxy group having 1 to 6 carbon atoms.
It is preferred that s is 0.

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

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

［式（ａ４－２）中、
Ｒ^f5は、水素原子又はメチル基を表す。
Ｌ⁴⁴は、炭素数１～６のアルカンジイル基を表し、該アルカンジイル基に含まれる－Ｃ
Ｈ₂－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
Ｒ^f6は、炭素数１～２０のフッ素原子を有する飽和炭化水素基を表す。
ただし、Ｌ⁴⁴及びＲ^f6の合計炭素数の上限は２１である。］ Examples of the structural unit represented by formula (a4-1) include a structural unit represented by formula (a4-2) and a structural unit 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,
H ₂ -- may be replaced by --O-- or --CO--.
R ^f6 represents a saturated hydrocarbon group having 1 to 20 carbon atoms and containing a fluorine atom.
However, the upper limit of the total number of carbon atoms in L ⁴⁴ and R ^f6 is 21.

Examples of the alkanediyl group having 1 to 6 carbon atoms for L ⁴⁴ include the same groups as those exemplified for A ^a41 .
Examples of the saturated hydrocarbon group of R ^f6 include the same groups as those exemplified for R ⁴² .
The alkanediyl group in L ⁴⁴ is preferably an alkanediyl group having 2 to 4 carbon atoms, more preferably an ethylene group.

Examples of the structural unit represented by formula (a4-2) include those represented by formulas (a4-1-1) to (a4
The structural unit represented by formula (a4-2) also includes a structural unit in which a methyl group corresponding to R ^f5 in the structural unit (a4-2) is replaced with a hydrogen atom.

［式（ａ４－３）中、
Ｒ^f7は、水素原子又はメチル基を表す。
Ｌ⁵は、炭素数１～６のアルカンジイル基を表す。
Ａ^f13は、フッ素原子を有していてもよい炭素数１～１８の２価の飽和炭化水素基を表
す。
Ｘ^f12は、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＡ^f13との結合部位を表す。
）。
Ａ^f14は、フッ素原子を有していてもよい炭素数１～１７の飽和炭化水素基を表す。
但し、Ａ^f13及びＡ^f14の少なくとも１つは、フッ素原子を有し、Ｌ⁵、Ａ^f13及びＡ^f14
の合計炭素数の上限は２０である。］

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

Examples of the alkanediyl group for ^L5 include the same groups as those exemplified as the alkanediyl group for ^Aa41 .

The divalent saturated hydrocarbon group for A ^f13 which may have a fluorine atom is preferably a divalent chain saturated hydrocarbon group which may have a fluorine atom and a divalent alicyclic saturated hydrocarbon group which may have a fluorine atom, and more preferably a perfluoroalkanediyl group.
Examples of the divalent chain saturated hydrocarbon group which may have a fluorine atom include alkanediyl groups such as a methylene group, an ethylene group, a propanediyl group, a butanediyl group, and a pentanediyl group; and perfluoroalkanediyl groups such as a difluoromethylene group, a perfluoroethylene group, a perfluoropropanediyl group, a perfluorobutanediyl group, and a perfluoropentanediyl group.
The divalent alicyclic saturated hydrocarbon group which may have a fluorine atom may be either monocyclic or polycyclic. Examples of the monocyclic group include a cyclohexanediyl group and a perfluorocyclohexanediyl group. Examples of the polycyclic group include an adamantanediyl group, a norbornanediyl group, and a perfluoroadamantanediyl group.

Examples of the saturated hydrocarbon group and the saturated hydrocarbon group which may have a fluorine atom of A ^f14 include the same groups as those exemplified for R ^a42 . Among them, a trifluoromethyl group, a difluoromethyl group, a methyl group, a perfluoroethyl group, a 2,2,2-trifluoroethyl group, a 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, perfluorohexyl group, heptyl group, perfluoroheptyl group, octyl group, perfluorooctyl group, and other fluorinated alkyl groups; cyclopropylmethyl group, cyclopropyl group, cyclobutylmethyl group, cyclopentyl group, cyclohexyl group, perfluorocyclohexyl group, adamantyl group, adamantylmethyl group, adamantyldimethyl group, norbornyl group, norbornylmethyl group, perfluoroadamantyl group, perfluoroadamantylmethyl group, and the like are preferred.

In formula (a4-3), L ⁵ is preferably an ethylene group.
The divalent saturated hydrocarbon group for 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, more preferably a divalent chain saturated hydrocarbon group having 2 to 3 carbon atoms.
The saturated hydrocarbon group of A ^f14 is a chain saturated hydrocarbon group having 3 to 12 carbon atoms and
A f14 is preferably a group containing an alicyclic saturated hydrocarbon group having 3 to 10 carbon atoms, and more preferably a group containing a chain saturated hydrocarbon group having 3 to 10 carbon atoms and an alicyclic saturated hydrocarbon group having 3 to 10 carbon atoms. Among these, A ^f14 is preferably a group containing an alicyclic saturated hydrocarbon group having 3 to 12 carbon atoms, and more preferably
Examples include a cyclopropylmethyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group.

Examples of the structural unit represented by formula (a4-3) include those represented by formulae (a4-1'-1) to (a
4-1'-11) are included. A structural unit in which a methyl group corresponding to ^Rf7 in the structural unit (a4-3) is replaced with a hydrogen atom is also included as a structural unit represented by formula (a4-3).

［式（ａ４－４）中、
Ｒ^f21は、水素原子又はメチル基を表す。
Ａ^f21は、－（ＣＨ₂）_j1－、－（ＣＨ₂）_j2－Ｏ－（ＣＨ₂）_j3－又は－（ＣＨ₂）_j4－
ＣＯ－Ｏ－（ＣＨ₂）_j5－を表す。
ｊ１～ｊ５は、それぞれ独立に、１～６のいずれかの整数を表す。
Ｒ^f22は、フッ素原子を有する炭素数１～１０の飽和炭化水素基を表す。］ The structural unit (a4) also includes a structural unit represented by formula (a4-4).

[In formula (a4-4),
R ^f21 represents a hydrogen atom or a methyl group.
A ^f21 is --(CH ₂ ) _j1 --, --(CH ₂ ) _j2 --O--(CH ₂ ) _j3 --, or --(CH ₂ ) _j4 --.
It represents CO—O—(CH ₂ ) _j5 —.
j1 to j5 each independently represent an integer of 1 to 6.
R ^f22 represents a saturated hydrocarbon group having 1 to 10 carbon atoms and containing a fluorine atom.]

Examples of the saturated hydrocarbon group of R ^f22 include the same as the saturated hydrocarbon group represented by R ^a42 . R ^f22 is preferably an alkyl group having 1 to 10 carbon atoms and containing a fluorine atom, or an alicyclic saturated hydrocarbon group having 1 to 10 carbon atoms and containing a fluorine atom, more preferably an alkyl group having 1 to 10 carbon atoms and containing a fluorine atom, and even more preferably an alkyl group having 1 to 6 carbon atoms and containing a fluorine atom.
In formula (a4-4), A ^f21 is preferably --(CH ₂ ) _j1 --, more preferably an ethylene group or a methylene group, and even more preferably a methylene group.

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

When the resin (A) has the structural unit (a4), the content thereof is preferably from 1 to 20 mol %, more preferably from 2 to 15 mol %, and even more preferably from 3 to 10 mol %, based on all structural units in the resin (A).

［式（ａ５－１）中、
Ｒ⁵¹は、水素原子又はメチル基を表す。
Ｒ⁵²は、炭素数３～１８の脂環式炭化水素基を表し、該脂環式炭化水素基に含まれる水
素原子は炭素数１～８の脂肪族炭化水素基で置換されていてもよい。
Ｌ⁵⁵は、単結合又は炭素数１～１８の２価の飽和炭化水素基を表し、該飽和炭化水素基
に含まれる－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。］ <Structural unit (a5)>
The non-leaving hydrocarbon group contained in the structural unit (a5) may be a group having a linear, branched or cyclic hydrocarbon group. Among these, the structural unit (a5) is preferably a group having an alicyclic hydrocarbon group.
An example of the structural unit (a5) is a structural unit represented by formula (a5-1).

[In formula (a5-1),
^R51 represents a hydrogen atom or a methyl group.
R ⁵² represents an alicyclic hydrocarbon group having 3 to 18 carbon atoms, and a hydrogen atom 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 --CH ₂ -- contained in the saturated hydrocarbon group may be replaced with --O-- or --CO--.]

The alicyclic hydrocarbon group in ^R52 may be either monocyclic or polycyclic. Examples of the monocyclic alicyclic hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the polycyclic alicyclic hydrocarbon group include an adamantyl group, a norbornyl group, and the like.
Examples of the aliphatic hydrocarbon group having 1 to 8 carbon atoms include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, and a 2-ethylhexyl group.
An example of the alicyclic hydrocarbon group having a substituent is a 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.

The divalent saturated hydrocarbon group for L ⁵⁵ includes a divalent chain saturated hydrocarbon group and a divalent alicyclic saturated hydrocarbon group, and is preferably a divalent chain saturated hydrocarbon group.
Examples of the divalent chain saturated hydrocarbon group include alkanediyl groups such as a methylene group, an ethylene group, a propanediyl group, a butanediyl group, and a pentanediyl group.
The divalent alicyclic saturated hydrocarbon group may be either monocyclic or polycyclic. Examples of the monocyclic alicyclic saturated hydrocarbon group include cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl. Examples of the polycyclic divalent alicyclic saturated hydrocarbon group include adamantanediyl and norbornanediyl.

式（Ｌ１－１）中、
Ｘ^x1は、＊－Ｏ－ＣＯ－又は＊－ＣＯ－Ｏ－を表す（＊はＬ^ｘ１との結合部位を表す。
）。
Ｌ^x1は、炭素数１～１６の２価の脂肪族飽和炭化水素基を表す。
Ｌ^x2は、単結合又は炭素数１～１５の２価の脂肪族飽和炭化水素基を表す。
ただし、Ｌ^x1及びＬ^x2の合計炭素数は、１６以下である。
式（Ｌ１－２）中、
Ｌ^x3は、炭素数１～１７の２価の脂肪族飽和炭化水素基を表す。
Ｌ^x4は、単結合又は炭素数１～１６の２価の脂肪族飽和炭化水素基を表す。
ただし、Ｌ^x3及びＬ^x4の合計炭素数は、１７以下である。
式（Ｌ１－３）中、
Ｌ^x5は、炭素数１～１５の２価の脂肪族飽和炭化水素基を表す。
Ｌ^x6及びＬ^x7は、それぞれ独立に、単結合又は炭素数１～１４の２価の脂肪族飽和炭化
水素基を表す。
ただし、Ｌ^x5、Ｌ^x6及びＬ^x7の合計炭素数は、１５以下である。
式（Ｌ１－４）中、
Ｌ^x8及びＬ^x9は、単結合又は炭素数１～１２の２価の脂肪族飽和炭化水素基を表す。
Ｗ^x1は、炭素数３～１５の２価の脂環式飽和炭化水素基を表す。
ただし、Ｌ^x8、Ｌ^x9及びＷ^x1の合計炭素数は、１５以下である。
Ｌ^x1は、好ましくは、炭素数１～８の２価の脂肪族飽和炭化水素基、より好ましくは、
メチレン基又はエチレン基である。
Ｌ^x2は、好ましくは、単結合又は炭素数１～８の２価の脂肪族飽和炭化水素基、より好
ましくは、単結合である。
Ｌ^x3は、好ましくは、炭素数１～８の２価の脂肪族飽和炭化水素基である。
Ｌ^x4は、好ましくは、単結合又は炭素数１～８の２価の脂肪族飽和炭化水素基である。
Ｌ^x5は、好ましくは、炭素数１～８の２価の脂肪族飽和炭化水素基、より好ましくは、
メチレン基又はエチレン基である。
Ｌ^x6は、好ましくは、単結合又は炭素数１～８の２価の脂肪族飽和炭化水素基、より好
ましくは、メチレン基又はエチレン基である。
Ｌ^x7は、好ましくは、単結合又は炭素数１～８の２価の脂肪族飽和炭化水素基である。
Ｌ^x8は、好ましくは、単結合又は炭素数１～８の２価の脂肪族飽和炭化水素基、より好
ましくは、単結合又はメチレン基である。
Ｌ^x9は、好ましくは、単結合又は炭素数１～８の２価の脂肪族飽和炭化水素基、より好
ましくは、単結合又はメチレン基である。
Ｗ^x1は、好ましくは、炭素数３～１０の２価の脂環式飽和炭化水素基、より好ましくは
、シクロヘキサンジイル基又はアダマンタンジイル基である。 Examples of the divalent saturated hydrocarbon group represented by L ⁵⁵ in which --CH ₂ -- is replaced by --O-- or --CO-- include groups represented by formulae (L1-1) to (L1-4). In the following formulae, * and ** each represent a bond, and * represents the bonding site with an oxygen atom.

In formula (L1-1),
X ^x1 represents *-O-CO- or *-CO-O- (* 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 of L ^x1 and L ^x2 is 16 or less.
In formula (L1-2),
L ^x3 represents a divalent aliphatic saturated hydrocarbon group having 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 of L ^x3 and L ^x4 is 17 or less.
In formula (L1-3),
L ^x5 represents a divalent aliphatic saturated hydrocarbon group having 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 of L ^x5 , L ^x6 and L ^x7 is 15 or less.
In formula (L1-4),
L ^x8 and L ^x9 each 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 of 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
It is 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
It is 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 the group represented by formula (L1-1) include the divalent groups shown below.

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

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

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

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

The structural unit (a5-1) may be any of the structural units shown below and the structural units (
a5-1) is a structural unit in which the methyl group corresponding to R ⁵¹ in the above formula (a5-1) is replaced with a hydrogen atom.

When the resin (A) has the structural unit (a5), the content thereof is preferably from 1 to 30 mol %, more preferably from 2 to 20 mol %, and even more preferably from 3 to 15 mol %, based on all structural units in the resin (A).

<Structural Unit (II)>
Resin (A) may further contain a structural unit that decomposes upon exposure to generate an acid (hereinafter, may be referred to as "structural unit (II)"). Specific examples of the structural unit (II) include the structural units described in JP2016-79235A. Preferably, the structural unit is a structural unit having a sulfonate group or carboxylate group and an organic cation in a side chain, or a structural unit having a sulfonio group and an organic anion in a side chain.

［式（ＩＩ－２－Ａ’）中、
Ｘ^ＩＩＩ３は、炭素数１～１８の２価の飽和炭化水素基を表し、該飽和炭化水素基に含
まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭
化水素基に含まれる水素原子は、ハロゲン原子、ハロゲン原子を有していてもよい炭素数
１～６のアルキル基又はヒドロキシ基で置き換わっていてもよい。
Ａ^ｘ１は、炭素数１～８のアルカンジイル基を表し、該アルカンジイル基に含まれる水
素原子は、フッ素原子又は炭素数１～６のペルフルオロアルキル基で置換されていてもよ
い。
ＲＡ^－は、スルホナート基又はカルボキシレート基を表す。
Ｒ^ＩＩＩ３は、水素原子、ハロゲン原子又はハロゲン原子を有していてもよい炭素数１
～６のアルキル基を表す。
ＺＡ^＋は、有機カチオンを表す。］ The structural unit having a sulfonate group or carboxylate group and an organic cation in the side chain is preferably a 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, in which -CH ₂ - contained in the saturated hydrocarbon group may be replaced by -O-, -S- or -CO-, and a hydrogen atom contained in the saturated hydrocarbon group may be replaced by a halogen atom, an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, or a hydroxy group.
A ^x1 represents an alkanediyl group having 1 to 8 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted by a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms.
^RA- represents a sulfonate group or a carboxylate group.
R ^III3 is a hydrogen atom, a halogen atom, or a C1 alkyl group which may have a halogen atom.
represents an alkyl group having a molecular weight of 1 to 6;
ZA ⁺ represents an organic cation.

Examples of the halogen atom represented by R ^III3 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom and which is represented by R ^III3 include the same as the alkyl group having 1 to 6 carbon atoms which may have a halogen atom and which is represented by R ^a8 .
Examples of the alkanediyl group having 1 to 8 carbon atoms represented by A ^x1 include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, an ethane-1,1-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-2,2-diyl group, a pentane-2,4-diyl group, a hexane-2,5-diyl group, a hexane-2,6-diyl group, a pentane-2,7-diyl group, a pentane-2,8-diyl group, a pentane-2,9-diyl group, a pentane-2,10-diyl group, a pentane-2,11-diyl group, a pentane-2,2-diyl group, a pentane-2,4-diyl group, a pentane-2,3-diyl group, a pentane-2,4-diyl group, a pentane-2,5-diyl group, a pentane-2,6-diyl group, a pentane-2,7-diyl group, a pentane-2,8-diyl group, a pentane-2,9-diyl group, a pentane-2,10-diyl group, a pentane-2,2-diyl group, a pentane-2,3-diyl group, a pentane-2,4-diyl group, a pentane-2,5-diyl group, a pentane-2,6-diyl group, a pentane-2,7-diyl group, a pentane-2,8-diyl group, a pentane-2,3-diyl group, a pentane-2,4-diyl group, a pentane-2,5-diyl group, a pentane-2,6-diyl group, a pent
Examples of the alkyl group include a diyl group, a 2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group, and a 2-methylbutane-1,4-diyl group.
Examples of the perfluoroalkyl group having 1 to 6 carbon atoms which may be substituted by A ^x1 include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butyl group, a perfluorotert-butyl group, a perfluoropentyl group, and a perfluorohexyl group.

Examples of the divalent saturated hydrocarbon group having 1 to 18 carbon atoms represented by ^XIII3 include linear or branched alkanediyl groups, and monocyclic or polycyclic divalent alicyclic saturated hydrocarbon groups, and combinations of these may also be used.
Specifically, a methylene group, an ethylene group, a propane-1,3-diyl group, a 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-
linear alkanediyl groups such as 1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, and dodecane-1,12-diyl group; butane-1,3-diyl group,
branched alkanediyl groups such as 2-methylpropane-1,3-diyl group, 2-methylpropane-1,2-diyl group, pentane-1,4-diyl group, and 2-methylbutane-1,4-diyl group; divalent monocyclic alicyclic saturated hydrocarbon groups such as cycloalkanediyl groups such as cyclobutane-1,3-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,4-diyl group, and cyclooctane-1,5-diyl group; norbornane-1,4-diyl group, norbornane-2,5-diyl group, adamantane-1,5-diyl group, adamantane-2,6-diyl group,
Examples of the divalent alkyl group include divalent polycyclic alicyclic saturated hydrocarbon groups such as a diyl group.

Examples of saturated hydrocarbon groups in which -CH ₂ - is replaced by -O-, -S- or -CO- include divalent groups represented by formulae (X1) to (X53), where the number of carbon atoms before -CH ₂ - is replaced by -O-, -S- or -CO- is 17 or less. In the following formulae, * and ** represent binding sites,
* indicates the binding site for ^Ax1 .

^X3 represents a divalent saturated hydrocarbon group having 1 to 16 carbon atoms.
X ⁴ 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 the organic cation represented by ZA ⁺ include the same as the cation Z1 ⁺ in the acid generator (B1).

［式（ＩＩ－２－Ａ）中、Ｒ^ＩＩＩ３、Ｘ^ＩＩＩ３及びＺＡ^＋は、上記と同じ意味を表
す。
ｚは、０～６のいずれかの整数を表す。
Ｒ^ＩＩＩ２及びＲ^ＩＩＩ４は、それぞれ独立して、水素原子、フッ素原子又は炭素数１
～６のペルフルオロアルキル基を表し、ｚが２以上のとき、複数のＲ^ＩＩＩ２及びＲ^{ＩＩ
Ｉ４}は互いに同一でも、異なっていてもよい。
Ｑ^ａ及びＱ^ｂは、それぞれ独立して、フッ素原子又は炭素数１～６のペルフルオロアル
キル基を表す。］ The structural unit represented by formula (II-2-A') is preferably a structural unit represented by formula (II-2-A).

In formula (II-2-A), R ^III3 , X ^III3 and ZA ⁺ are as defined above.
z represents an integer of 0 to 6.
R ^III2 and R ^III4 each independently represent a hydrogen atom, a fluorine atom, or a group having 1 carbon atom.
When z is 2 or more, a plurality of R ^III2 and R ^II
I4 may be the same or different.
Q ^a and Q ^b each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms.

Examples of the perfluoroalkyl group having 1 to 6 carbon atoms represented by R ^III2 , R ^III4 , Q ^a and Q ^b include the same perfluoroalkyl groups having 1 to 6 carbon atoms represented by Q ^b1 described above.

［式（ＩＩ－２－Ａ－１）中、
Ｒ^ＩＩＩ２、Ｒ^ＩＩＩ３、Ｒ^ＩＩＩ４、Ｑ^a、Ｑ^b、ｚ及びＺＡ^＋は、上記と同じ意味を
表す。
Ｒ^ＩＩＩ５は、炭素数１～１２の飽和炭化水素基を表す。
Ｘ^Ｉ2は、炭素数１～１１の２価の飽和炭化水素基を表し、該飽和炭化水素基に含まれ
る－ＣＨ_２－は、－Ｏ－、－Ｓ－又は－ＣＯ－に置き換わっていてもよく、該飽和炭化水
素基に含まれる水素原子は、ハロゲン原子又はヒドロキシ基で置換されていてもよい。］
Ｒ^ＩＩＩ５で表される炭素数１～１２の飽和炭化水素基としては、メチル基、エチル基
、プロピル基、イソプロピル基、ブチル基、ｓｅｃ－ブチル基、ｔｅｒｔ－ブチル基、ペ
ンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基及
びドデシル基等の直鎖又は分岐のアルキル基が挙げられる。
Ｘ^Ｉ２で表される２価の飽和炭化水素基としては、Ｘ^ＩＩＩ３で表される２価の飽和炭
化水素基と同様のものが挙げられる。 The structural unit represented by formula (II-2-A) is preferably a 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 meanings as above.
R ^III5 represents a saturated hydrocarbon group having 1 to 12 carbon atoms.
X ^I2 represents a divalent saturated hydrocarbon group having 1 to 11 carbon atoms, -CH ₂ - contained in the saturated hydrocarbon group may be replaced by -O-, -S- or -CO-, and a hydrogen atom contained in the saturated hydrocarbon group may be replaced by a halogen atom or a hydroxyl group.]
Examples of the saturated hydrocarbon group having 1 to 12 carbon atoms represented by R ^III5 include linear or branched alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group.
Examples of the divalent saturated hydrocarbon group represented by X ^I2 include the same as the divalent saturated hydrocarbon group represented by X ^III3 .

［式（ＩＩ－２－Ａ－２）中、Ｒ^ＩＩＩ３、Ｒ^ＩＩＩ５及びＺＡ^＋は、上記と同じ意味
を表す。
ｍ及びｎは、それぞれ独立に、１又は２を表す。］ The structural unit represented by formula (II-2-A-1) is preferably a structural unit represented by formula (II-2-A-2).

In formula (II-2-A-2), R ^III3 , R ^III5 and ZA ⁺ are as defined above.
m and n each independently represent 1 or 2.

Examples of the structural unit represented by formula (II-2-A') include the following structural units and structural units described in WO 2012/050015: ZA ⁺ represents an organic cation.

［式（ＩＩ－１－１）中、
Ａ^ＩＩ１は、単結合又は２価の連結基を表す。
Ｒ^ＩＩ１は、炭素数６～１８の２価の芳香族炭化水素基を表す。
Ｒ^ＩＩ２及びＲ^ＩＩ３は、それぞれ独立して、炭素数１～１８の炭化水素基を表し、Ｒ
^ＩＩ２及びＲ^ＩＩ３は互いに結合してそれらが結合する硫黄原子とともに環を形成してい
てもよい。
Ｒ^ＩＩ４は、水素原子、ハロゲン原子又はハロゲン原子を有していてもよい炭素数１～
６のアルキル基を表す。
Ａ^－は、有機アニオンを表す。］
Ｒ^ＩＩ１で表される炭素数６～１８の２価の芳香族炭化水素基としては、フェニレン基
及びナフチレン基等が挙げられる。
Ｒ^ＩＩ２及びＲ^ＩＩ３で表される炭化水素基としては、アルキル基、脂環式炭化水素基
、芳香族炭化水素基及びこれらを組み合わせることにより形成される基等が挙げられる。
アルキル基及び脂環式炭化水素基は、上記と同様のものが挙げられる。
芳香族炭化水素基としては、フェニル基、ナフチル基、アントリル基、ビフェニル基、
フェナントリル基等のアリール基が挙げられる。
組み合わせた基としては、上述したアルキル基と脂環式炭化水素基とを組み合わせた基
、ベンジル基等のアラルキル基、アルキル基を有する芳香族炭化水素基（ｐ－メチルフェ
ニル基、ｐ－ｔｅｒｔ－ブチルフェニル基、トリル基、キシリル基、クメニル基、メシチ
ル基、２，６－ジエチルフェニル基、２－メチル－６－エチルフェニル基等）、脂環式炭
化水素基を有する芳香族炭化水素基（ｐ－シクロヘキシルフェニル基、ｐ－アダマンチル
フェニル基等）、フェニルシクロヘキシル基等のアリール－シクロアルキル基等が挙げら
れる。
Ｒ^ＩＩ４で表されるハロゲン原子としては、フッ素原子、塩素原子、臭素原子及びヨウ
素原子等が挙げられる。
Ｒ^ＩＩ４で表されるハロゲン原子を有していてもよい炭素数１～６のアルキル基として
は、Ｒ^ａ８で表されるハロゲン原子を有していてもよい炭素数１～６のアルキル基と同じ
ものが挙げられる。
Ａ^ＩＩ１で表される２価の連結基としては、例えば、炭素数１～１８の２価の飽和炭化
水素基が挙げられ、該２価の飽和炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－又
は－ＣＯ－で置き換わっていてもよい。具体的には、Ｘ^ＩＩＩ３で表される炭素数１～１
８の２価の飽和炭化水素基と同じものが挙げられる。 The structural unit having a sulfonio group and an organic anion in the side chain is preferably a 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; R
^II2 and R ^II3 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.
R ^II4 is a hydrogen atom, a halogen atom, or a C 1-
6 represents an alkyl group.
A ⁻ represents an organic anion.
Examples of the divalent aromatic hydrocarbon group having 6 to 18 carbon atoms represented by R ^II1 include a phenylene group and a naphthylene group.
Examples of the hydrocarbon group represented by R ^II2 and R ^II3 include an alkyl group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a group formed by combining these groups.
Examples of the alkyl group and the alicyclic hydrocarbon group include the same as those mentioned above.
Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a biphenyl group,
Examples of the aryl group include a phenanthryl group.
Examples of the combined group include a combination of the above-mentioned alkyl group and alicyclic hydrocarbon group, aralkyl groups such as a benzyl group, aromatic hydrocarbon groups having an alkyl group (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 an alicyclic hydrocarbon group (p-cyclohexylphenyl group, p-adamantylphenyl group, etc.), and aryl-cycloalkyl groups such as a phenylcyclohexyl group.
Examples of the halogen atom represented by ^RII4 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkyl group having 1 to 6 carbon atoms which may have a halogen atom and which is represented by R ^II4 include the same as the alkyl group having 1 to 6 carbon atoms which may have a halogen atom and which is represented by R ^a8 .
Examples of the divalent linking group represented by A ^II1 include a divalent saturated hydrocarbon group having ¹ to 18 carbon atoms, and -CH ₂ - contained in the divalent saturated hydrocarbon group may be replaced by -O-, -S- or -CO-.
Examples of the divalent saturated hydrocarbon group include the same as the divalent saturated hydrocarbon group of 8.

Examples of the structural unit containing a cation in formula (II-1-1) include structural units represented below.

Examples of the organic anion represented by ^A- include a sulfonate anion, a sulfonylimide anion, a sulfonylmethide anion, a carboxylate anion, etc. The organic anion represented by ^A- is preferably a sulfonate anion, and the sulfonate anion is more preferably an anion contained in the salt represented by the above-mentioned formula (B1).

Examples of the sulfonylimide anion represented by A 1 ^- include the following.

Examples of sulfonylmethide anions include the following:

Examples of carboxylate anions include the following:

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

When the resin (A) contains the structural unit (II), the content of the structural unit (II) is preferably 1 to 20 mol %, more preferably 2 to 5 mol %, based on the total structural units of the resin (A).
It is preferably 15 mol %, and more preferably 3 to 10 mol %.

The resin (A) may have structural units other than the above-mentioned structural units, and examples of such structural units include structural units well known in the art.
The resin (A) is preferably a resin containing the structural unit (a1-1), the structural unit (a1-2), and the structural unit (a2-A), i.e., a copolymer containing structural units derived from the monomers (a1-1), (a1-2), and (a2-A).

Each structural unit constituting the resin (A) may be used alone or in combination of two or more, and can be produced by a known polymerization method (e.g., radical polymerization method) using a monomer that derives these structural units. The content of each structural unit in the resin (A) can be adjusted by the amount of the monomer used in the polymerization.
The weight average molecular weight of the resin (A) is preferably 2,000 or more (more preferably 2.5
00 or more, more preferably 3,000 or more), 50,000 or less (more preferably 30
In the present specification, the weight average molecular weight is a value determined 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 a resin other than the resin (A).
Examples of resins other than resin (A) include resins containing the structural unit (a4) or the structural unit (a5) (hereinafter, sometimes referred to as resin (X)).
As the resin (X), a resin containing the structural unit (a4) is particularly preferred.
In the resin (X), the content of the structural unit (a4) is preferably 30 mol % or more, more preferably 40 mol % or more, and even more preferably 45 mol % or more, based on the total amount of all structural units in the resin (X).
Examples of structural units that the resin (X) may further have include the structural unit (a2), the structural unit (a3), and structural units derived from other known monomers.
X) is preferably a resin consisting only of the structural unit (a4) and/or the structural unit (a5), and more preferably a resin consisting only of the structural unit (a4).
Each structural unit constituting the resin (X) may be used alone or in combination of two or more kinds.
The resin (X) can be produced by a known polymerization method (for example, radical polymerization method) using monomers that derive these structural units. The content of each structural unit in the resin (X) can be adjusted by the amount of the monomer used in the polymerization.
The weight average molecular weight of each of the resins (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 method for measuring the weight average molecular weight of the resin (X) is the same as that for the resin (A).
When the resist composition contains resin (X), the content thereof 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, particularly preferably 1 to 30 parts by mass, and particularly preferably 1 to 8 parts by mass, relative to 100 parts by mass of resin (A).

The content of the resin (A) in the resist composition is 8 to 100% based on the solid content of the resist composition.
Preferably, the content is 0% by mass or more and 99% by mass or less, and more preferably 90% by mass or more and 99% by mass or less. When a resin other than the resin (A) is contained, the total content of the resin (A) and the resin other than the resin (A) is preferably 80% by mass or more and 99% by mass or less, and more preferably 90% by mass or more and 99% by mass or less, based on the solid content of the resist composition. In this specification, the "solid content of the resist composition" refers to the ratio of the solvent (E
The solids content of the resist composition and the resin content therein can be measured by known analytical means such as liquid chromatography or gas chromatography.

［式（Ｉ）中、
Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、それぞれ独立に、水素原子、ハロゲン原子、ニトロ基又
は炭素数１～２４の炭化水素基を表し、該炭化水素基に含まれる－ＣＨ_２－は、－Ｏ－、
－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていてもよい。
Ｘ^１は、ニトロ基、－ＣＯ－Ｒ^５又は－ＳＯ_２－Ｒ^６を表す。
Ｒ^５及びＲ^６は、それぞれ独立に、炭素数１～２４の炭化水素基を表し、該炭化水素基
に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－、－ＣＯ－又は－ＳＯ_２－に置き換わっていて
もよい。
ＺＩ^＋は、有機カチオンを表す。］
塩（Ｉ）のうち、負電荷を有する側を「アニオン（Ｉ）」、正電荷を有する側を「カチ
オン（Ｉ）」と称することがある。 [Salt represented by formula (I)]
The resist composition of the present invention contains a salt (I).

[In formula (I),
R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group or a hydrocarbon group having 1 to 24 carbon atoms, and the -CH ₂ - contained in the hydrocarbon group is -O-,
It may be replaced by --S--, --CO-- or --SO ₂ --.
^X1 represents a nitro group, —CO— ^R5 or —SO ₂ ^—R6 .
R ⁵ and R ⁶ each independently represent a hydrocarbon group having 1 to 24 carbon atoms, and --CH ₂ -- contained in the hydrocarbon group may be replaced by --O--, --S--, --CO-- or --SO ₂ --.
ZI ⁺ represents an organic cation.
In the salt (I), the negatively charged side is sometimes referred to as the "anion (I)" and the positively charged side is sometimes referred to as the "cation (I)".

Examples of the hydrocarbon group represented by ^R1 , ^R2 , ^R3 , ^R4 , ^R5 , and ^R6 include aliphatic hydrocarbon groups (chain hydrocarbon groups such as alkyl groups, alkenyl groups, and alkynyl groups, and alicyclic hydrocarbon groups), aromatic hydrocarbon groups, and combinations of these groups.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group,
Examples of the alkyl group include an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, etc. The number of carbon atoms in the alkyl group is preferably 1 to 9, and more preferably 1 to 4.
Examples of the alkenyl group include an ethenyl group, a propenyl group, an isopropenyl group, and a butenyl group.
an isobutenyl group, a tert-butenyl group, a pentenyl group, a hexenyl group, a heptenyl group,
Examples of such groups include an octynyl group, an isooctynyl group, and a nonenyl group.
Examples of the alkynyl group include an ethynyl group, a propynyl group, an isopropynyl group, a butynyl group,
isobutynyl group, tert-butynyl group, pentynyl group, hexynyl group, octynyl group,
Examples thereof include a nonynyl group.
The alicyclic hydrocarbon group may be any of monocyclic, polycyclic and spirocyclic, and may be any of saturated and unsaturated. Examples of the alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclononyl, cyclodecyl and cyclododecyl, and polycyclic cycloalkyl groups such as norbornyl and adamantyl.
The alicyclic hydrocarbon group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be a group represented by the formula (Y
The groups represented by the formulas (Y1) to (Y41) (where * represents a bonding position) are preferred, and the groups represented by the formulas (Y1) to (Y
More preferably, the group is a group represented by any one of formulas (Y20), (Y26), (Y27), (Y30), (Y31), (Y39) and (Y40), and the group is represented by formulas (Y3), (Y4):
, formula (Y9), formula (Y11), formula (Y14), formula (Y15), formula (Y20), formula (Y30
), and more preferably a group represented by formula (Y39) or formula (Y40). The alicyclic hydrocarbon group preferably has 3 to 18 carbon atoms, and more preferably has 3 to 16 carbon atoms.

Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a biphenyl group,
Examples of the aryl group include aryl groups such as a phenanthryl group and a fluorenyl group. Of these, a phenyl group, a naphthyl group and an anthryl group are preferred, a phenyl group and a naphthyl group are more preferred, and a phenyl group is even more preferred.

The combined groups of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are
a group combining an alicyclic hydrocarbon group with a chain hydrocarbon group (such as an alkyl group, an alkenyl group and/or an alkynyl group) ( _-CH2- contained in the chain hydrocarbon group (such as an alkyl group, an alkenyl group and an alkynyl group) and the alicyclic hydrocarbon group may be replaced by -O-, -S-, -CO- or _-SO2- );
A group in which a chain hydrocarbon group and an aromatic hydrocarbon group are combined (the --CH ₂ -- contained in the chain hydrocarbon group (an alkyl group, an alkenyl group, an alkynyl group, etc.) is not an --O--, --S--, --CO--, --O ...
- or -SO ₂ -), and a group combining an alicyclic hydrocarbon group with an aromatic hydrocarbon group (-CH ₂ - contained in the alicyclic hydrocarbon group may be replaced by -O-, -S-, -CO- or -SO ₂ -).
The alkynyl group and the aromatic hydrocarbon group may each be a combination of two or more kinds.
Specifically, the combined groups are:
Alicyclic hydrocarbon group such as adamantylmethyl group, cyclohexylmethyl group, etc.--chain hydrocarbon group-* (-CH ₂ - contained in the chain hydrocarbon group and the alicyclic hydrocarbon group is -O-, -
may be replaced by -S-, -CO- or -SO ₂ -),
a chain hydrocarbon group such as a methyladamantyl group - an alicyclic hydrocarbon group -* ( _-CH2- contained in the chain hydrocarbon group and the alicyclic hydrocarbon group may be replaced by -O-, -S- or -CO-);
chain hydrocarbon group-aromatic hydrocarbon group-*, such as tolyl group, xylyl group, cyclohexylphenyl group, etc.; alicyclic hydrocarbon group-aromatic hydrocarbon group-* (-CH ₂ - contained in the chain hydrocarbon group and the alicyclic hydrocarbon group may be replaced by -O-, -S-, -CO- or -SO ₂ -);
A chain hydrocarbon group such as a methylcyclohexylmethyl group--alicyclic hydrocarbon group--a chain hydrocarbon group-* (-CH ₂ - contained in the chain hydrocarbon group and the alicyclic hydrocarbon group is -O-, -
may be replaced by -S-, -CO- or -SO ₂ -),
an aromatic hydrocarbon group such as a benzyl group - a chain hydrocarbon group -* ( _-CH2- contained in the chain hydrocarbon group may be replaced by -O-, -S-, -CO- or _-SO2- );
A chain hydrocarbon group such as a tolylmethyl group--aromatic hydrocarbon group--a chain hydrocarbon group--* (-CH ₂ - contained in the chain hydrocarbon group may be replaced by -O-, -S-, -CO- or -SO ₂ -)
Here, * indicates the bonding position with a carbon atom.

When —CH ₂ — contained in the hydrocarbon groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is replaced with —O—, —S—, —CO— or —SO ₂ —, the number of carbon atoms before replacement is regarded as the total number of carbon atoms in the hydrocarbon group.
Examples of the hydrocarbon group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in which -CH ₂ - is replaced by -O-, -S-, -CO- or -SO ₂ - include a hydroxy group (a group in which -CH ₂ - in a methyl group is replaced by -O-), a carboxy group (a group in which -CH ₂ -CH ₂ - in an ethyl group is replaced by -O-CO-), an alkoxy group having 1 to 12 carbon atoms (a group in which -CH ₂ - in an alkyl group having 2 to 13 carbon atoms is replaced by -O-), an alkoxycarbonyl group having 2 to 13 carbon atoms (a group in which -CH _{2 -CH 2 - in an alkyl group having 4 to 15 carbon atoms is replaced by -O-CO-), an alkylcarbonyl group having 2 to 13 carbon atoms (a group in which -CH 2} -CH _{2 -} in an alkyl group having 3 to 14 carbon atoms is replaced by -CO-
and alkylcarbonyloxy groups having 2 to 13 carbon atoms (groups in which --CH ₂ --CH ₂ -- contained in an alkyl group having 4 to 15 carbon atoms is replaced with --CO--O--).

Examples of the alkoxy group having 1 to 12 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a 2-ethylhexyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, and a dodecyloxy group.
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 and/or a carbonyloxy group is bonded to the above-mentioned alkyl group or alkoxy group.
Examples of the alkoxycarbonyl group having 2 to 13 carbon atoms include a methoxycarbonyl group, an ethoxycarbonyl group, and a butoxycarbonyl group. Examples of the alkylcarbonyl group having 2 to 13 carbon atoms include an acetyl group, a propionyl group, and a butyryl group.
The alkylcarbonyloxy group of 3 is an acetyloxy group, a propionyloxy group,
butyryloxy group and the like.

R ¹ is preferably a hydrogen atom, a halogen atom, a nitro group, -CO-R ⁵ or -SO ₂ -R ⁶ , more preferably a hydrogen atom, a halogen atom or a nitro group, even more preferably a halogen atom, and even more preferably a fluorine atom.
R ⁴ is preferably a hydrogen atom, a halogen atom, a nitro group, -CO-R ⁵ or -SO ₂ -R ⁶ , more preferably a hydrogen atom, a halogen atom or a nitro group, even more preferably a hydrogen atom or a halogen atom, and even more preferably a hydrogen atom or a fluorine atom. R ² and R ³ are preferably hydrogen atoms.
^R5 and ^R6 each represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,
R 5 is preferably an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and R ⁶ is preferably an alkyl group having 1 to 6 carbon atoms or ^an alkyl group having 1 to 4 carbon atoms-aromatic hydrocarbon group having 5 to 10 carbon atoms.
X ¹ is preferably a nitro group, an alkylcarbonyl group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms-aromatic hydrocarbon group having 5 to 10 carbon atoms-sulfonyl group, or an alkanesulfonyl group having 1 to 6 carbon atoms, and more preferably a nitro group, an alkylcarbonyl group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, or an alkanesulfonyl group having 1 to 6 carbon atoms.
More preferably, it is an alkanesulfonyl group having a substituent of 1 to 6.

Examples of the anion (I) include anions represented by the following formulae (Ia-1) to (Ia-24). Among them, the anions represented by the formulae (Ia-1) to (Ia-8) and (Ia-17)
, an anion represented by formula (Ia-18) is preferred.

The organic cation of ZI ⁺ may be an organic onium cation, an organic sulfonium cation,
Examples of the cation include an organic iodonium cation, an organic ammonium cation, a benzothiazolium cation, and an organic phosphonium cation. Among these, an organic sulfonium cation and an organic iodonium cation are preferred, and an arylsulfonium cation is more preferred. Specific examples include the cations represented by any one of formulas (b2-1) to (b2-4) exemplified in Z1 ⁺ .

Examples of the salt (I) include the salts shown in Table 1. For example, in Table 1, salt (I-1)
means a salt composed of an anion represented by formula (Ia-1) and a cation represented by formula (b2-c-1), and represents the salt shown below.

Among them, the salt (I) includes salts (I-1) to (I-8), salt (I-17), and salt (I-18).
), salt (I-25) to salt (I-32), salt (I-41), salt (I-42), salt (I-49)
) to salt (I-56), salt (I-65), salt (I-66), salt (I-73) to salt (I-80)
), salt (I-89), salt (I-90), salt (I-97) to salt (I-104), salt (I-1
13), salt (I-114), salt (I-121) to salt (I-128), salt (I-137),
Salt (I-138), Salt (I-145) to Salt (I-152), Salt (I-161), Salt (I-
162) is preferred.

（式中、全ての符号は、それぞれ前記と同じ意味を表す。）
溶媒としては、アセトニトリル、クロロホルム、テトラヒドロフラン及び水などが挙げ
られる。
反応は、通常１５～８０℃の温度範囲で、０．５～２４時間行われる。 <Method for producing salt (I)>
The salt (I) can be obtained by reacting a compound represented by formula (I-a) with sodium hydroxide in a solvent, and then further reacting the resulting mixture with a salt represented by formula (I-b).

(In the formula, all symbols have the same meaning as defined above.)
Solvents include acetonitrile, chloroform, tetrahydrofuran, and water.
The reaction is usually carried out at a temperature ranging from 15 to 80° C. for 0.5 to 24 hours.

Examples of the compound represented by formula (Ia) include compounds represented by the following formula, and are readily available on the market.

Examples of the salt represented by formula (Ib) include the salt represented by the following formula, which are readily available on the market.

<Solvent (E)>
The content of the solvent (E) in the resist composition is usually from 90% by mass to 99.9% by mass, preferably from 92% by mass to 99% by mass, and more preferably from 94% by mass to 99% by mass. The content of the solvent (E) can be measured by a known analytical method such as liquid chromatography or gas chromatography.
Examples of the 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; cyclic esters such as γ-butyrolactone; and the like. One type of solvent (E) may be used alone.
Two or more types may be used.

<Quencher (C)>
Examples of the quencher (C) include basic nitrogen-containing organic compounds and salts (excluding the salt (I)) that generate an acid weaker in acidity than the acid generated by the acid generator (B).
The content of the quencher (C) is preferably about 0.01 to 5 mass % based on the solid content of the resist composition.
The basic nitrogen-containing organic compound includes amines and ammonium salts. The amines include aliphatic amines and aromatic amines. The 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, tributylamine,
Tripentylamine, trihexylamine, triheptylamine, trioctylamine,
Trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine,
Methyldioctylamine, methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, 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)ethane, 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 are included, preferably aromatic amines such as diisopropylaniline, more preferably 2,6-diisopropylaniline.
Examples of the ammonium salt include tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide, 3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylammonium salicylate, and choline.

The acidity of a salt that generates an acid weaker than the acid generated from the acid generator (B) is
It is expressed by an acid dissociation constant (pKa). A salt that generates an acid weaker in acidity than the acid generated from the acid generator (B) is a salt having an acid dissociation constant of usually −3<pKa, preferably −1<pKa<7, and more preferably 0<pKa<5.
Examples of the salt that generates an acid having a weaker acidity than the acid generated from the acid generator (B) include a salt represented by the following formula, a salt represented by formula (D) described in JP-A-2015-147926 (hereinafter, referred to as "
Weak acid inner salt (D)" and JP2012-229206A, JP2012-6908A, JP2012-72109A, JP2011-3
Examples of the salt that generates an acid having a weaker acidity than the acid generated from the acid generator (B) include the salts described in JP-A-9502 and JP-A-2011-191745. A weak acid inner salt (D) is preferable as the salt that generates an acid having a weaker acidity than the acid generated from the acid generator (B).

Examples of the weak acid inner salt (D) include the following salts.

When the resist composition contains a quencher (C), the content of the quencher (C) is usually from 0.01 to 5 mass % in the solid content of the resist composition, and preferably from 0.01 to 5 mass %.
It is 3% by mass.

<Other Ingredients>
The resist composition of the present invention may contain components other than the above-mentioned components (hereinafter, sometimes referred to as "other components (F)") as necessary. There are no particular limitations on the 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 comprises an acid generator (B), a salt (I) and a resin (A), and, if necessary, a resin other than the resin (A), a solvent (E), a quencher (C) and other components (
F). The order of mixing is arbitrary and is not particularly limited. The temperature during mixing ranges from 10 to 40°C, depending on the type of resin, solvent for resin, etc. (
An appropriate temperature can be selected depending on the solubility of the component (A) in E) and the like. An appropriate mixing time can be selected from 0.5 to 24 hours depending on the mixing temperature. There are no particular limitations on the mixing means, and stirring and mixing can be used.
After mixing the components, it is preferable to filter the mixture using a filter having a pore size of about 0.003 to 0.2 μm.

<Method for Producing Resist Pattern>
The method for producing a resist pattern of the present invention comprises the steps of:
(1) applying the resist composition of the present invention onto a substrate;
(2) A step of drying the applied composition to form a composition layer;
(3) exposing the composition layer to light;
(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 onto a substrate using a commonly used device such as a spin coater. Examples of the substrate include inorganic substrates such as silicon wafers. Before applying the resist composition, the substrate may be cleaned, and an anti-reflective film or the like may be formed on the substrate.
The composition after coating is dried to remove the solvent and form a composition layer.
For example, drying can be performed 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. The pressure during reduced pressure drying is preferably about 1 to 1.0×10 ⁵ Pa.
The obtained composition layer is usually exposed using an exposure machine. The exposure machine may be an immersion exposure machine. As the exposure light source, various types can be used, such as those that emit ultraviolet laser light such as KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), and _F2 excimer laser (wavelength 157 nm), those that convert the wavelength of laser light from a solid laser light source (YAG or semiconductor laser, etc.) to emit harmonic laser light in the far ultraviolet or vacuum ultraviolet range, and those that irradiate electron beams or extreme ultraviolet light (EUV). In this specification, irradiation with these radiations may be collectively referred to as "exposure". During exposure, exposure is usually performed through a mask corresponding to the desired pattern. When 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 a heat treatment (so-called post-exposure bake) in order to promote the deprotection reaction of the acid labile groups. The heating temperature is usually about 50 to 200°C, preferably about 70 to 150°C.
The composition layer after heating is usually developed using a developing device with a developer. Examples of the developing method include a dip method, a paddle method, a spray method, and a dynamic dispense method. The developing temperature is preferably, for example, 5 to 60° C., and the developing time is, for example, 5 to 60° C.
By selecting the type of developer as follows, a positive resist pattern or a negative resist pattern can be produced.
When a positive resist pattern is produced from the resist composition of the present invention, an alkaline developer is used as the developer. The alkaline developer may be any of various alkaline aqueous solutions used in this field. Examples include aqueous solutions of tetramethylammonium hydroxide and (2-hydroxyethyl)trimethylammonium hydroxide (commonly known as choline).
The alkaline developer may contain a surfactant.
After development, the resist pattern is preferably washed with ultrapure water, and then water remaining on the substrate and the pattern is removed.
When producing a negative resist pattern from the resist composition of the present invention, a developer containing an organic solvent (hereinafter sometimes referred to as an "organic developer") is used as the developer.
Examples of the organic solvent contained in the organic developer 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,
The content is more preferably from 95% by mass to 100% by mass, and further preferably consists essentially of an organic solvent.
Among them, the organic developer is preferably a developer containing butyl acetate and/or 2-heptanone. The total content of butyl acetate and 2-heptanone in the organic developer is 50% by mass.
The content is preferably from 90% by mass to 100% by mass, more preferably from 90% by mass to 100% by mass, and further preferably substantially composed of only butyl acetate and/or 2-heptanone.
The organic developer may contain a surfactant and may contain a small amount of water.
During development, the development may be stopped by replacing the organic developer with a different type of solvent.
It is preferable to wash the resist pattern after development with a rinse solution.
There are no particular limitations as long as the solvent does not dissolve the resist pattern, and a solution containing a general organic solvent can be used, with alcohol solvents or ester solvents being preferred.
After cleaning, it is preferable to remove any rinsing liquid remaining on the substrate and the pattern.

<Application>
The resist composition of the present invention is a resist composition for KrF excimer laser exposure, a resist composition for ArF excimer laser exposure, a resist composition for electron beam (EB) exposure, or a resist composition for EU
The resist composition is suitable for V exposure, particularly for ArF excimer laser 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" expressing the content or amount used are based on mass unless otherwise specified.
The weight average molecular weight is a value determined by gel permeation chromatography under the following analytical conditions:
Column: TSKgel Multipore HXL-M x 3+guardcolumn (Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min
Detector: RI detector Column temperature: 40℃
Injection volume: 100 μl
Molecular weight standard: Standard polystyrene (Tosoh Corporation)
The structure of the compound was determined by mass spectrometry (LC: Agilent 1100, MASS: Agilent
The molecular ion peak was measured using an LC/MSD spectrometer (manufactured by Ent) and confirmed. In the following examples, the value of the molecular ion peak is indicated by "MASS".

Synthesis Example 1: Synthesis of a salt represented by formula (I-1)
1 part of the compound represented by formula (I-1-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.31 parts of sodium hydroxide was added, and further
The mixture was stirred at 23° C. for 1 hour. To the resulting reaction mixture, 2.0 of a salt represented by formula (I-1-b) was added.
After stirring at 23° C. for 1 hour, the organic layer was separated and taken out. After stirring at 23° C. for 30 minutes, 5 parts of ion-exchanged water was added to the obtained organic layer, and the organic layer was separated and taken out. This water washing operation was repeated three times. After concentrating the obtained organic layer, 10 parts of tert-butyl methyl ether was added to the concentrated residue, and the organic layer was separated and taken out.
After stirring at 3° C. for 30 minutes, the mixture was filtered to obtain 1.30 parts of the salt represented by formula (I-1).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 156.0

Synthesis Example 2: Synthesis of a salt represented by formula (I-2)
1 part of the compound represented by formula (I-2-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.34 parts of sodium hydroxide was added, and further
The mixture was stirred at 23° C. for 1 hour. The resulting reaction mixture was added with a salt represented by formula (I-1-b) 2.3
2 parts of ethyl acetate, 10 parts of chloroform and 5 parts of ion-exchanged water were added and stirred at 23°C for 1 hour, and then the organic layer was separated and taken out. 5 parts of ion-exchanged water was added to the obtained organic layer and stirred at 23°C for 30 minutes, and then the organic layer was separated and taken out. This water washing operation was repeated three times. The obtained organic layer was concentrated, and then 10 parts of tert-butyl methyl ether was added to the concentrated residue and washed with 2
After stirring at 3° C. for 30 minutes, the mixture was filtered to obtain 1.22 parts of the salt represented by formula (I-2).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 174.0

Synthesis Example 3: Synthesis of a salt represented by formula (I-3)
1 part of the compound represented by formula (I-3-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.38 parts of sodium hydroxide was added, and further
The mixture was stirred at 23° C. for 1 hour. To the resulting reaction mixture, 2.5 g of a salt represented by formula (I-1-b) was added.
After 3 parts of ethyl acetate, 11 parts of chloroform and 5 parts of ion-exchanged water were added and stirred at 23°C for 1 hour, the organic layer was separated and taken out. 5 parts of ion-exchanged water was added to the obtained organic layer and stirred at 23°C for 30 minutes, the organic layer was separated and taken out. This water washing operation was repeated three times. After concentrating the obtained organic layer, 10 parts of tert-butyl methyl ether was added to the concentrated residue and washed with water for 2 hours.
After stirring at 3° C. for 30 minutes, the mixture was filtered to obtain 1.48 parts of the salt represented by formula (I-3).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 189.0

Synthesis Example 4: Synthesis of a salt represented by formula (I-5)
1 part of the compound represented by formula (I-5-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.30 parts of sodium hydroxide was added, and further,
The mixture was stirred at 23° C. for 1 hour. To the resulting reaction mixture, 2.0 of a salt represented by formula (I-1-b) was added.
After stirring at 23° C. for 1 hour, the organic layer was separated and taken out. To the obtained organic layer, 5 parts of ion-exchanged water was added and stirred at 23° C. for 30 minutes, and the organic layer was separated and taken out. This water-washing operation was repeated three times. The obtained organic layer was concentrated to obtain 1.14 parts of the salt represented by formula (I-5).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 153.0

Synthesis Example 5: Synthesis of a salt represented by formula (I-7)
1 part of the compound represented by formula (I-7-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.33 parts of sodium hydroxide was added, and further,
The mixture was stirred at 23° C. for 1 hour. The resulting reaction mixture was added with a salt 2.2 represented by formula (I-1-b)
After stirring at 23° C. for 1 hour, the organic layer was separated and taken out. To the obtained organic layer, 5 parts of ion-exchanged water was added and stirred at 23° C. for 30 minutes, and the organic layer was separated and taken out. This water-washing operation was repeated three times. The obtained organic layer was concentrated to obtain 1.21 parts of the salt represented by formula (I-7).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 169.0

Synthesis Example 6: Synthesis of a salt represented by formula (I-8)
1 part of the compound represented by formula (I-8-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.37 parts of sodium hydroxide was added, and further
The mixture was stirred at 23° C. for 1 hour. To the resulting reaction mixture, 2.5 g of a salt represented by formula (I-1-b) was added.
After stirring at 23° C. for 1 hour, the organic layer was separated and taken out. To the obtained organic layer, 5 parts of ion-exchanged water was added and stirred at 23° C. for 30 minutes, and the organic layer was separated and taken out. This water-washing operation was repeated three times. The obtained organic layer was concentrated to obtain 1.49 parts of a salt represented by formula (I-8).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 187.0

Synthesis Example 7: Synthesis of a salt represented by formula (I-56)
1 part of the compound represented by formula (I-8-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.37 parts of sodium hydroxide was added, and further
The mixture was stirred for 1 hour at 23° C. To the resulting reaction mixture, a salt 2. represented by formula (I-56-b) was added.
66 parts of the mixture, 15 parts of chloroform and 3 parts of ion-exchanged water were added and stirred at 23° C. for 1 hour.
The organic layer was separated and the organic layer was taken out. Five parts of ion-exchanged water was added to the obtained organic layer and the mixture was stirred at 23° C. for 30 minutes.
After stirring for 10 minutes, the mixture was separated and the organic layer was taken out. This water washing procedure was repeated three times. The obtained organic layer was concentrated to obtain 1.51 parts of the salt represented by formula (I-56).
MASS (ESI (+) Spectrum): M ⁺ 281.1
MASS (ESI (-) Spectrum): M ^- 187.0

Synthesis Example 8: Synthesis of a salt represented by formula (I-80)
1 part of the compound represented by formula (I-8-a), 4 parts of acetonitrile, and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, and then 0.37 parts of sodium hydroxide was added, and further
The mixture was stirred for 1 hour at 23° C. To the resulting reaction mixture, a salt 2. represented by formula (I-80-b) was added.
96 parts of the mixture, 15 parts of chloroform and 3 parts of ion-exchanged water were added and stirred at 23° C. for 1 hour.
The organic layer was separated and the organic layer was taken out. Five parts of ion-exchanged water was added to the obtained organic layer and the mixture was stirred at 23° C. for 30 minutes.
After stirring for 10 minutes, the mixture was separated and the organic layer was taken out. This water washing procedure was repeated three times. The obtained organic layer was concentrated to obtain 1.62 parts of the salt represented by formula (I-80).
MASS (ESI (+) Spectrum): M ⁺ 317.1
MASS (ESI (-) Spectrum): M ^- 187.0

Synthesis Example 9: Synthesis of a salt represented by formula (IX-1)
1 part of the compound represented by formula (IX-1-a), 4 parts of acetonitrile and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, after which 0.19 parts of sodium hydroxide was added and further stirred at 23° C. for 1 hour. The resulting reaction mixture was treated with 1.
26 parts of toluene, 8 parts of chloroform and 2 parts of ion-exchanged water were added and stirred at 23°C for 1 hour, and then the organic layer was separated and taken out. 5 parts of ion-exchanged water was added to the obtained organic layer and stirred at 23°C for 30 minutes, and then the organic layer was separated and taken out. This water washing operation was repeated three times. The obtained organic layer was concentrated to obtain 0.78 parts of the salt represented by formula (IX-1).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 93.0

Synthesis Example 10: Synthesis of a salt represented by formula (IX-2)
1 part of the compound represented by formula (IX-2-a), 4 parts of acetonitrile and 2 parts of ion-exchanged water were mixed and stirred at 23° C. for 30 minutes, after which 0.36 parts of sodium hydroxide was added and further stirred at 23° C. for 1 hour. The resulting reaction mixture was treated with 2.
Add 46 parts of the mixture, 15 parts of chloroform and 3 parts of ion-exchanged water, and stir at 23° C. for 1 hour.
The organic layer was separated and the organic layer was taken out. Five parts of ion-exchanged water was added to the obtained organic layer and the mixture was stirred at 23° C. for 30 minutes.
After stirring for 10 minutes, the mixture was separated and the organic layer was taken out. This water washing procedure was repeated three times. The obtained organic layer was concentrated to obtain 1.22 parts of the salt represented by formula (IX-2).
MASS (ESI (+) Spectrum): M ⁺ 263.1
MASS (ESI (-) Spectrum): M ^- 183.0

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

Synthesis Example 11 [Synthesis of Resin A1]
As the monomers, monomer (a1-4-2), monomer (a1-1-3) and monomer (a1-2-6) were used, and the molar ratio of monomer (a1-4-2):monomer (a1-1) was
monomer (a1-2-6)) were mixed in a ratio of 38:24:38,
Further, 1.5 times by mass of methyl isobutyl ketone was mixed with this monomer mixture relative to the total mass of all monomers. Azobisisobutyronitrile was added as an initiator to the obtained mixture so that the amount was 7 mol % relative to the total molar number of all monomers, and polymerization was carried out by heating the mixture at 85° C. for about 5 hours. Thereafter, an aqueous p-toluenesulfonic acid solution was added to the polymerization reaction liquid, and the mixture was stirred for 6 hours and then separated. The recovered organic layer was poured into a large amount of n-heptane to precipitate a resin, which was then filtered and recovered to obtain a resin having a weight average molecular weight of about 5.
Resin A1 (copolymer) having an average molecular weight of 3.3 x 10 ³ was obtained in a yield of 78%. This resin A1 has the following structural units.

Synthesis Example 12 [Synthesis of Resin A2]
Monomer (a1-4-2) and monomer (a1-2-6) were used as monomers and mixed in a molar ratio of 49:51 [monomer (a1-4-2):monomer (a1-2-6)], and 1.5 times by mass of methyl isobutyl ketone was mixed with the monomer mixture based on the total mass of all monomers. Azobisisobutyronitrile was added as an initiator to the obtained mixture in an amount of 7 mol% based on the total mole number of all monomers.
The mixture was heated at 85°C for about 5 hours to polymerize. Thereafter, an aqueous p-toluenesulfonic acid solution was added to the polymerization reaction solution, and the mixture was stirred for 6 hours and then separated. The recovered organic layer was poured into a large amount of n-heptane to precipitate a resin, which was then filtered and recovered to obtain Resin A2 (copolymer) having a weight average molecular weight of about 5.9 x ¹⁰³ in a yield of 88%.
This resin A2 has the following structural units.

Synthesis Example 13: Synthesis of resin AX1 As monomers, monomer (a1-1-3), monomer (a1-2-2), and monomer (
Monomer (a1-1-3):monomer (a1-2-2):monomer (a2-1-1) and monomer (a3-1-1) were used, and the molar ratio of monomer (a1-1-3):monomer (a1-2-2):monomer (a2-1-
1):monomer (a3-1-1):monomer (a3-2-2)] in a ratio of 30:14:6:30
: 20, and propylene glycol monomethyl ether acetate was added in an amount of 1.5 times the mass of the total monomer amount to obtain a solution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were added as initiators to this solution at 1 mol% and 3 mol% relative to the total monomer amount, respectively, and heated at 73 ° C. for about 5 hours. The resulting reaction mixture was poured into a large amount of a methanol / water mixed solvent to precipitate the resin, and the resin was filtered. The obtained resin was again dissolved in propylene glycol monomethyl ether acetate, and the resulting solution was poured into a methanol / water mixed solvent to precipitate the resin, and the resin was filtered. This reprecipitation operation was performed twice, and resin AX1 with a weight average molecular weight of 8.0 × 10 ³ was obtained in a yield of 64%. This resin AX1 has the following structural units.

<Preparation of Resist Composition>
The components shown in Table 2 were mixed and dissolved to obtain a mixture, which was then filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a resist composition.

＜クエンチャー（Ｃ）＞
Ｃ１：特開２０１１－３９５０２号公報記載の方法で合成

＜溶剤＞
プロピレングリコールモノメチルエーテルアセテート ４００部
プロピレングリコールモノメチルエーテル １５０部
γ－ブチロラクトン ５部 <Resin>
A1, A2, AX1: Resin A1, Resin A2, Resin AX1
<Acid Generator (B)>
B1-43: Salt represented by formula (B1-43) (synthesized according to the examples in JP 2016-47815 A)

<Quencher (C)>
C1: Synthesized by the method described in JP-A-2011-39502

<Solvent>
Propylene glycol monomethyl ether acetate 400 parts Propylene glycol monomethyl ether 150 parts γ-butyrolactone 5 parts

(Electron Beam Exposure Evaluation of Resist Composition: Alkaline Development)
A 6-inch silicon wafer was treated with hexamethyldisilazane on a direct hot plate at 90°C for 60 seconds. The resist composition was spin-coated onto this silicon wafer so that the film thickness of the composition layer became 0.04 µm. The wafer was then pre-baked on a direct hot plate for 60 seconds at the temperature shown in the "PB" column of Table 2 to form a composition layer. The composition layer formed on the wafer was then irradiated with an electron beam lithography machine [HL-800D manufactured by Hitachi, Ltd.].
A line and space pattern was directly written by changing the exposure dose stepwise using a laser beam having an energy of 50 keV.
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 for 60 seconds with a 2.38 mass % aqueous tetramethylammonium hydroxide solution to obtain a resist pattern.
The obtained resist pattern (line and space pattern) was observed under a scanning electron microscope, and the exposure amount at which the line width and space width of a 60 nm line and space pattern became 1:1 was defined as the effective sensitivity.

Line edge roughness evaluation (LER): The amplitude of unevenness on the sidewall surface of the resist pattern produced at the effective sensitivity was measured by a scanning electron microscope to obtain the line edge roughness. The results are shown in Table 3.

The salt of the present invention and a resist composition containing this salt provide a resist pattern with excellent line edge roughness (LER), and are therefore suitable for semiconductor microfabrication and extremely useful industrially.

Claims (4)

A resist composition comprising a salt represented by formula (I) and a resin including a structural unit represented by formula (a2-A) .

[In formula (I),
R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a halogen atom, a nitro group or a hydrocarbon group having 1 to 24 carbon atoms, in which -CH ₂ - may be replaced by -O-, -S-, -CO- or -SO ₂ - , and at least one of R ¹ , R ² , R ³ and R ⁴ represents a halogen atom .
^X1 represents a nitro group, —CO— ^R5 or —SO ₂ ^—R6 .
R ⁵ and R ⁶ each independently represent a hydrocarbon group having 1 to 24 carbon atoms, and --CH ₂ -- contained in the hydrocarbon group may be replaced by --O--, --S--, --CO-- or --SO ₂ --.
ZI ⁺ represents a cation represented by formula (b2-1) .

[ In formula (b2-1) ,
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, a hydrogen atom contained in the chain hydrocarbon group may be substituted with a hydroxy 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, a hydrogen atom contained 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, and a hydrogen atom contained in the aromatic hydrocarbon group may be substituted with a halogen atom, a hydroxy group, or an alkoxy group having 1 to 12 carbon atoms.
R ^b4 and R ^b5 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, and --CH ₂ -- contained in the ring may be replaced with --O--, --S-- or --CO-- .]

[In formula (a2-A),
R ^a50 represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom.
R ^a51 represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyl group having 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, an acryloyloxy group or a methacryloyloxy group.
A ^a50 represents a single bond or *-X ^a51 -(A ^a52 -X ^a52 ) _na -, where * represents a bond to the carbon atom to which -R ^a50 is bonded.
A ^a52 represents an alkanediyl group having 1 to 6 carbon atoms.
X ^a51 and X ^a52 each independently represent —O—, —CO—O— or —O—CO—.
na represents 0 or 1.
mb represents an integer of 0 to 4. When mb is an integer of 2 or more, multiple R ^a51 may be the same or different. 2. The resist composition according to claim 1, wherein ^X1 is a nitro group, a methanesulfonyl group, a methylcarbonyl group or a methoxycarbonyl group. 3. The resist composition according to claim 1, wherein R ¹ is a halogen atom. the content of the structural unit represented by formula (a2-A) in the resin is 20 to 65 mol % based on the total structural units of the resin,
2. The resist composition according to claim 1, further comprising an acid generator, the content of the acid generator being from 5 parts by mass to 40 parts by mass relative to 100 parts by mass of the resin.