JP7846641B2 - Resist material and pattern formation method - Google Patents

Description

This invention relates to a resist material and a pattern forming method.

With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. This is because the proliferation of 5G high-speed communication and artificial intelligence (AI) necessitates high-performance devices to process them. At the forefront of miniaturization technology, mass production of 5nm node devices is underway using extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm. Furthermore, research using EUV lithography is progressing for next-generation 3nm node and even the following-generation 2nm node devices.

As miniaturization progresses, image blurring due to acid diffusion is becoming a problem. To ensure resolution in fine patterns of 45 nm and beyond, it has been suggested that controlling acid diffusion is crucial, in addition to improving dissolution contrast as previously proposed (Non-Patent Literature 1). However, since chemically amplified resist materials increase sensitivity and contrast through acid diffusion, attempting to suppress acid diffusion to the extreme by lowering the post-exposure bake (PEB) temperature or shortening the time results in a significant decrease in sensitivity and contrast.

The relationship between sensitivity, resolution, and edge roughness in a triangle trade-off is shown. Improving resolution requires suppressing acid diffusion, but reducing the acid diffusion distance decreases sensitivity.

Adding an acid generator that produces bulky acids to suppress acid diffusion is effective. Therefore, it has been proposed to incorporate repeating units derived from onium salts having polymerizable unsaturated bonds into the polymer. In this case, the polymer also functions as an acid generator (polymer-bound type acid generator). Patent Document 1 proposes sulfonium salts and iodonium salts having polymerizable unsaturated bonds that generate specific sulfonic acids. Patent Document 2 proposes sulfonium salts in which sulfonic acids are directly linked to the main chain.

The acid-unstable groups used in (meth)acrylate polymers for ArF resist materials undergo deprotection reactions by using a photoacid generator that produces sulfonic acid with a fluorine atom substituted at the α-position. However, deprotection reactions do not proceed with acid generators that produce sulfonic acid or carboxylic acid without a fluorine atom substituted at the α-position. When a sulfonium salt or iodonium salt that produces sulfonic acid with a fluorine atom substituted at the α-position is mixed with a sulfonium salt or iodonium salt that produces sulfonic acid without a fluorine atom substituted at the α-position, the sulfonium salt or iodonium salt that produces sulfonic acid without a fluorine atom substituted at the α-position undergoes ion exchange with the sulfonic acid with a fluorine atom substituted at the α-position. Since the sulfonic acid with a fluorine atom substituted at the α-position generated by light reverts back to the sulfonium salt or iodonium salt through ion exchange, the sulfonium salt or iodonium salt of sulfonic acid or carboxylic acid without a fluorine atom substituted at the α-position functions as a quencher. A resist material has been proposed that uses a sulfonium salt or iodonium salt that generates a carboxylic acid as a quencher (Patent Document 3).

Various sulfonium salt type quenchers that generate various carboxylic acids have been proposed. In particular, sulfonium salts of salicylic acid and β-hydroxycarboxylic acid (Patent Document 4), salicylic acid derivatives (Patent Documents 5 and 6), fluorosalicylic acid (Patent Document 7), and hydroxynaphthoic acid (Patent Document 8) have been shown. Salicylic acid, in particular, has the effect of suppressing acid diffusion through intramolecular hydrogen bonding between the carboxylic acid and the hydroxyl group.

On the other hand, it has been pointed out that quencher aggregation reduces the dimensional uniformity of the resist pattern. By preventing quencher aggregation in the resist film and homogenizing its distribution, it is expected that the dimensional uniformity of the pattern after development will be improved.

The trifluoromethoxy group is called a superhalogen due to its strong electron-withdrawing effect and is used in pharmaceuticals, agrochemicals, and liquid crystal materials. 4-trifluoromethoxybenzoic acid has been shown as an anion for sulfonium salts used in resists (Patent Document 9).

Japanese Patent Publication No. 2006-045311 Japanese Patent Publication No. 2006-178317 Japanese Patent Publication No. 2007-114431 WO2018/159560 Japanese Patent Publication No. 2020-203984 Japanese Patent Publication No. 2020-91404 WO2010/095698 Japanese Patent Publication No. 2019-120760 Japanese Patent Publication No. 2007-284405

SPIE Vol. 6520 65203L-1 (2007)

This invention has been made in view of the above circumstances, and aims to provide a resist material that is highly sensitive, has improved LWR (line width roughness) and CDU (dimensional uniformity), and a pattern formation method using the same, whether it is a positive or negative type resist.

In order to solve the above problems, the present invention provides:
As a quencher,
The present invention provides a resist material comprising a substituted or unsubstituted sulfonium salt of hydroxy(trifluoromethoxy)benzoic acid, and/or a substituted or unsubstituted sulfonium salt of hydroxy(trifluoromethylthio)benzoic acid.

Such materials, whether positive or negative, will be highly sensitive and exhibit improved LWR and CDU (low wave ratio).

It is preferable that the sulfonium salt of the substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid, and/or the sulfonium salt of the substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid, is represented by the following general formula (1).
(In the formula, ^R1 is a hydrogen atom, or a group selected from linear, branched, or cyclic alkyl, alkoxy, alkoxycarbonyl, or acyl groups having 1 to 15 carbon atoms, or alkenyl or alkynyl groups having 2 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may also be an acid-unstable group. X is an oxygen atom or a sulfur atom. m and n are 1 or 2, respectively. ^R2 to ^R4 are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. ^R2 and ^R3 may also be bonded to each other to form a ring with the sulfur atom to which they are bonded.)

Such a material can be used to create a resist material that is more reliably sensitive and has improved LWR and CDU.

Furthermore, in this invention,
As a quencher,
The present invention provides a resist material comprising one or more of the following: a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethoxy)benzoic acid, a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethylthio)benzoic acid, a sulfonium salt of 2- or 3-di or trifluoromethoxybenzoic acid, and a sulfonium salt of 2- or 3-di or trifluoromethylthiobenzoic acid.

Such materials, whether positive or negative, will be highly sensitive and exhibit improved LWR and CDU (low wave ratio).

It is preferable that one or more of the above-mentioned substituted or unsubstituted sulfonium salts of hydroxy(difluoromethoxy)benzoic acid, substituted or unsubstituted sulfonium salts of hydroxy(difluoromethylthio)benzoic acid, sulfonium salts of 2- or 3-di or trifluoromethoxybenzoic acid, and sulfonium salts of 2- or 3-di or trifluoromethylthiobenzoic acid are represented by the following general formula (1').
(In the formula, R ^1' is a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted amino group, or a linear, branched, or cyclic alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, alkenyloxy group, or alkynyloxy group having 1 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may be an acid-unstable group. However, if R ¹ ' is a _hydrogen atom, the substitution position of the C-X- group is at position 2 or 3. _p is 0 or 1, q is 2 or 3. X is an oxygen atom or a sulfur atom. m and n are 1 or 2, respectively. ^{R 2} to R ⁴ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ² and R ( ³ may bond to each other, forming a ring with the sulfur atom to which they are bonded.)

Such a material can be used to create a resist material that is more reliably sensitive and has improved LWR and CDU.

Furthermore, it is preferable that the product contains an acid-generating agent that produces acid.

In this configuration, the sulfonium salt described above functions as a quencher, and the resist material of the present invention functions accordingly.

It is preferable that the acid generating agent generates sulfonic acid, imido acid, or methidoic acid.

Such a material is more suitable as an acid generator.

Furthermore, it is preferable that it contains an organic solvent.

With this type of material, each component can be dissolved and used suitably as a resist material.

Furthermore, it is preferable that the product contains a base polymer.

Such a material would be suitable as a resist material.

Preferably, the base polymer contains repeating units represented by the following general formula (a1) and/or repeating units represented by the following general formula (a2).
(In the formula, R ^A is independently a hydrogen atom or a methyl group. ^{Y 1} is a carbon-1 to carbon-12 linking group containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond and a lactone ring. ^{Y 2} is a single bond or an ester bond. ^{Y 3} is a single bond, an ether bond or an ester bond. ^{R 11} and R ¹² are independently acid-unstable groups. ^{R 13} is a fluorine atom, a trifluoromethyl group, a cyano group, or a carbon-1 to carbon-6 saturated hydrocarbyl group. R ¹⁴ is a single bond or a carbon-1 to carbon-6 alkanediyl group, some of which carbon atoms may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer from 0 to 4, where 1 ≤ a + b ≤ 5.)

Such a material, containing acid-unstable groups, is suitable as a positive-type resist material.

The resist material is preferably a chemically amplified positive-type resist material.

The resist material of the present invention can function as a chemically amplified positive-type resist material.

It is also preferable that the base polymer does not contain acid-unstable groups.

Such a material, free from acid-unstable groups, is suitable as a negative-type resist material.

The resist material is preferably a chemically amplified negative-type resist material.

The resist material of the present invention can function as a chemically amplified negative resist material.

Preferably, the base polymer further contains at least one repeating unit selected from the following general formulas (f1) to (f3).
(In the formula, R ^A is independently a hydrogen atom or a methyl group. Z ¹ is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z ^11- , -C(=O)-O-Z ^11- or -C(=O)-NH-Z ^11- . Z ¹¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. ^{Z 2} is a single bond or an ester bond. Z ³ is a single bond, -Z ³¹ -C(=O)-O-, -Z ³¹ -O- or -Z ³¹ -O-C(=O)-. Z ³¹ is a C1-C12 hydrocarbylene group, a phenylene group, or a C7-C18 group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. ^Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. ^Z5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O- ^Z51- , -C(=O)-O- ^Z51- , or -C(=O)-NH- ^Z51- . ⁵¹ is a phenylene group substituted with an aliphatic hydrocarbylene group, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group having 1 to 15 carbon atoms, or a combination thereof, and may also contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and/or a hydroxyl group. R ²¹ to R ²⁸ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ²³ and R ²⁴ or R ²⁶ and R ²⁷ may bond to each other to form a ring with the sulfur atom to which they are bonded. ^M- is a non-nucleophilic counterion.

Such a substance would function as an acid generator within the base polymer.

Furthermore, it is preferable that it contains a surfactant.

With this type of material, it is possible to improve or control the applicability of the resist material.

Furthermore, the present invention provides a pattern formation method characterized by comprising the steps of: forming a resist film on a substrate using the above-mentioned resist material; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer solution.

This pattern formation method allows for the creation of good patterns.

It is preferable to use KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet light with a wavelength of 3 to 15 nm as the high-energy beam.

Using such high-energy rays allows for the formation of better patterns.

The sulfonium salts of substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid, and/or the sulfonium salts of substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid, are quenchers that suppress acid diffusion. This results in low acid diffusion properties, improving LWR and CDU. Therefore, it is possible to construct highly sensitive resist materials with low LWR and improved CDU.

In resist materials, there is a need for the development of a quencher that can improve the LWR of line patterns and the dimensional uniformity (CDU) of hole patterns, while also enhancing sensitivity. To achieve this, it is necessary to further reduce image blurring due to diffusion.

The inventors, through diligent research to achieve the above objectives, have discovered that a resist material to which substituted or unsubstituted sulfonium salts of hydroxy(di or trifluoromethoxy)benzoic acid, substituted or unsubstituted sulfonium salts of hydroxy(di or trifluoromethylthio)benzoic acid, sulfonium salts of 2- or 3-di or trifluoromethoxybenzoic acid, or sulfonium salts of 2- or 3-di or trifluoromethylthiobenzoic acid are added acts as a quencher to suppress acid diffusion. The excellent acid diffusion suppression effect due to the presence of substituted or unsubstituted hydroxyl and carboxyl groups within the anion molecule, the improved dissolution contrast when the hydroxyl group is substituted with an acid-unstable group, and the high electron-withdrawing effect and the prevention of quencher aggregation due to electron repulsion of bulky groups due to the presence of trifluoromethoxy or trifluoromethylthio groups improve LWR and CDU, resulting in a resist material with excellent resolution and a wide process margin. This discovery has led to the completion of the present invention.

In other words, the present invention is
As a quencher,
The resist material comprises a sulfonium salt of substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid, and/or a sulfonium salt of substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid.

Furthermore, the present invention,
As a quencher,
The resist material comprises one or more of the following: a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethoxy)benzoic acid, a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethylthio)benzoic acid, a sulfonium salt of 2- or 3-di or trifluoromethoxybenzoic acid, and a sulfonium salt of 2- or 3-di or trifluoromethylthiobenzoic acid.

The present invention will be described in detail below, but it is not limited to these descriptions.

[Resist material]
The resist material of the present invention contains, as a quencher, one or more of the following: a substituted or unsubstituted sulfonium salt of hydroxy(trifluoromethoxy)benzoic acid, and/or a substituted or unsubstituted sulfonium salt of hydroxy(trifluoromethylthio)benzoic acid, or a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethoxy)benzoic acid, a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethylthio)benzoic acid, a sulfonium salt of 2- or 3-di or trifluoromethoxybenzoic acid, and a sulfonium salt of 2- or 3-di or trifluoromethylthiobenzoic acid.

[Sulfonium salts of substituted or unsubstituted hydroxy(di or trifluoromethoxy)benzoic acid, sulfonium salts of substituted or unsubstituted hydroxy(di or trifluoromethylthio)benzoic acid, sulfonium salts of 2- or 3-di or trifluoromethoxybenzoic acid, sulfonium salts of 2- or 3-di or trifluoromethylthiobenzoic acid]
Preferably, one or more of the above-mentioned substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid sulfonium salts, and/or substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid sulfonium salts, substituted or unsubstituted hydroxy(difluoromethoxy)benzoic acid sulfonium salts, substituted or unsubstituted hydroxy(difluoromethylthio)benzoic acid sulfonium salts, 2- or 3-di or trifluoromethoxybenzoic acid sulfonium salts, and 2- or 3-di or trifluoromethylthiobenzoic acid sulfonium salts (hereinafter also referred to as sulfonium salt A) are represented by the following general formula (1) and the following general formula (1').

In the above general formula (1), ^R1 is a hydrogen atom, or a group selected from linear, branched, or cyclic alkyl, alkoxy, alkoxycarbonyl, or acyl groups having 1 to 15 carbon atoms, an alkenyl or alkynyl group having 2 to 15 carbon atoms, and the group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may also be an acid-unstable group. X is an oxygen atom or a sulfur atom. m and n are each 1 or 2. ^R2 to ^R4 are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Furthermore, ^R2 and ^R3 may be bonded to each other to form a ring with the sulfur atom to which they are bonded.

In the above general formula (1'), R ^1' is a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted amino group, or a linear, branched, or cyclic alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, alkenyloxy group, or alkynyloxy group having 1 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may be an acid-unstable group. However, if R ¹ ' is a hydrogen atom, the substitution position of the C-X- group is at position _{2 or} 3. p is 0 or 1, and q is 2 or 3. X is an oxygen atom or a sulfur atom. m and n are each 1 or 2. ^{R 2} to R ⁴ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Furthermore, ^R2 and ^R3 may bond to each other, forming a ring with the sulfur atom to which they are bonded.

The anions of the sulfonium salt represented by the general formula (1) above include, but are not limited to, those listed below.

Examples of anions of sulfonium salts represented by the above general formula (1') include, but are not limited to, those shown as specific examples of anions of sulfonium salts represented by the above general formula (1), and those shown below.

In the above general formulas (1) and (1'), ^R2 to ^R4 are each independently a hydrocarbyl group having 1 to 25 carbon atoms, preferably 1 to 20 carbon atoms, which may contain a halogen atom or a heteroatom.

Examples of halogen atoms represented by ^R2 to ^R4 include fluorine, chlorine, bromine, and iodine atoms.

The hydrocarbyl groups, represented by ^R2 to ^R4 and having 1 to 25 carbon atoms, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C25 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups; C3-C25 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C25 alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl groups; and ethynyl groups. Examples include alkynyl groups having 2 to 25 carbon atoms, such as propynyl and butynyl groups; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 25 carbon atoms, such as cyclohexenyl and norbornenyl groups; aryl groups having 6 to 25 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, and tert-butylnaphthyl groups; aralkyl groups having 7 to 25 carbon atoms, such as benzyl and phenethyl groups; and groups obtained by combining these.

Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the _-CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a mercapto group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

Furthermore, ^R2 and ^R3 may bond to each other, forming a ring with the sulfur atom to which they are bonded. In this case, the ring is preferably structured as shown below.
(In the equation, the dashed line represents the connection with R ^4. )

The cations of the sulfonium salts represented by the above general formulas (1) and (1') include, but are not limited to, those listed below.

Sulfonium salt A can be synthesized, for example, by ion exchange of a hydrochloride or carbonate containing a sulfonium cation with substituted or unsubstituted hydroxytrifluoromethoxybenzoic acid or substituted or unsubstituted hydroxytrifluoromethylthiobenzoic acid.

In the resist material of the present invention, the content of sulfonium salt A is preferably 0.001 to 50 parts by mass, and more preferably 0.01 to 40 parts by mass, per 100 parts by mass of the base polymer described later. Sulfonium salt A may be used alone or in combination of two or more types.

[Base polymer]
The resist material of the present invention may contain a base polymer. In the case of a positive-type resist material, the base polymer contains repeating units containing acid-unstable groups. The repeating units containing acid-unstable groups are preferably the repeating units represented by the following general formula (a1) (hereinafter also referred to as repeating unit a1) and/or the repeating units represented by the following general formula (a2) (hereinafter also referred to as repeating unit a2).

In the above general formulas (a1) and (a2), R ^A is independently a hydrogen atom or a methyl group. Y ¹ is a carbon-1 to carbon-12 linking group containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond and a lactone ring. ^{Y 2} is a single bond or an ester bond. Y ³ is a single bond, an ether bond or an ester bond. ^{R 11} and R ¹² are independently acid-unstable groups. Note that if the above base polymer contains both repeating units a1 and a2, R ¹¹ and R ¹² may be the same or different from each other. R ¹³ is a fluorine atom, a trifluoromethyl group, a cyano group or a carbon-1 to carbon-6 saturated hydrocarbyl group. R ¹⁴ is a single bond or a carbon-1 to carbon-6 alkanediyl group, and some of its carbon atoms may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer between 0 and 4, where 1 ≤ a + b ≤ 5.

Examples of monomers that give repeating unit a1 include, but are not limited to, those listed below. In the following formula, R ^A and R ¹¹ are the same as above.

Examples of monomers that give repeating unit a2 include, but are not limited to, those listed below. In the following formula, R ^A and R ¹² are the same as above.

Examples of acid-unstable groups represented by ^R1 , ^R1' , ^R11 , and ^R12 in the above general formulas (1), (1'), (a1), and (a2) include those described in Japanese Patent Publication No. 2013-80033 and Japanese Patent Publication No. 2013-83821.

Typically, the above-mentioned acid-unstable groups include those represented by the following general formulas (AL-1) to (AL-3).
(In the equation, dashed lines represent connections.)

In the above general formulas (AL-1) and (AL-2), R ^L1 and R ^L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A saturated hydrocarbyl group having 1 to 40 carbon atoms is preferred, and a saturated hydrocarbyl group having 1 to 20 carbon atoms is more preferred.

In the above general formula (AL-1), c is an integer between 0 and 10, preferably between 1 and 5.

In the above general formula (AL-2), R ^L3 and R ^L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A saturated hydrocarbyl group having 1 to 20 carbon atoms is preferred as the hydrocarbyl group. Furthermore, any two of R ^L2 , R ^L3 , and R ^L4 may bond to each other to form a ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded, or with an oxygen atom. A ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

In the above general formula (AL-3), R ^L5 , R ^L6 , and R ^L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A saturated hydrocarbyl group having 1 to 20 carbon atoms is preferred as the hydrocarbyl group. Furthermore, any two of R ^L5 , R ^L6 , and R ^L7 may bond to each other to form a ring having 3 to 20 carbon atoms together with the carbon atoms to which they are bonded. A ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

When the base polymer of the above-mentioned resist material contains repeating units a1 and a2, it is a chemically amplified positive-type resist material.

It is also preferable that the base polymer of the above-mentioned resist material does not contain acid-unstable groups; in this case, the resist material is a chemically amplified negative-type resist material.

The above base polymer may contain repeating units b that include a phenolic hydroxyl group as an adhesion group. Examples of monomers that give repeating units b are, but are not limited to, those listed below. In the following formula, R ^A is the same as above.

The above base polymer may also contain repeating units c as other adhesive groups, including hydroxyl groups other than phenolic hydroxyl groups, lactone rings, sultone rings, ether bonds, ester bonds, sulfonic acid ester bonds, carbonyl groups, sulfonyl groups, cyano groups, and/or carboxyl groups. Examples of monomers that give repeating units c are, but are not limited to, those listed below. In the following formulas, R ^A is the same as above.

The above base polymer may contain repeating units d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Examples of monomers that give repeating units d are, but are not limited to, those listed below.

The above base polymer may contain repeating units e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindan, vinylpyridine, or vinylcarbazole.

The above base polymer may contain repeating units f derived from an onium salt containing polymerizable unsaturated bonds. Preferred repeating units f include the repeating unit represented by the following general formula (f1) (hereinafter also referred to as repeating unit f1), the repeating unit represented by the following general formula (f2) (hereinafter also referred to as repeating unit f2), and the repeating unit represented by the following general formula (f3) (hereinafter also referred to as repeating unit f3). Repeating units f1 to f3 may be used individually or in combination of two or more.

In the above general formulas (f1) to (f3), R ^A is independently a hydrogen atom or a methyl group. ^Z1 is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -O- ^Z11- , -C(=O)-O- ^Z11- , or -C(=O)-NH- ^Z11- . ^Z11 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may include a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. ^Z2 is a single bond or an ester bond. ^Z3 is a single bond, ^-Z31 -C(=O)-O-, ^-Z31 -O-, or ^-Z31 -O-C(=O)-. ^Z31 is a C1-C12 hydrocarbylene group, a phenylene group, or a C7-C18 group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. ^Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. ^Z5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O- ^Z51- , -C(=O)-O- ^Z51- , or -C(=O)-NH- ^Z51- . Z ⁵¹ is a phenylene group substituted with an aliphatic hydrocarbylene group having 1 to 15 carbon atoms, preferably 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group, or a combination thereof, and may also contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and/or a hydroxyl group.

In the above general formulas (f1) to (f3), ^R21 to ^R28 are each independently a hydrocarbyl group having 1 to 25 carbon atoms, preferably 1 to 20 carbon atoms, which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified as the hydrocarbyl groups represented by ^R2 to ^R4 in the explanation of general formulas (1) and (1') above. The above hydrocarbyl group may have some or all of its hydrogen atoms substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. Also, ^R23 and ^R24 or ^R26 and ^R27 may bond to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the above ring is similar to the ring that can be formed when ^R2 and ^R3 bond together with the sulfur atom to which they are bonded in the explanation of the above general formulas (1) and (1').

In the above general formula (f1), ^M- is a non-nucleophilic counterion. Examples of the above non-nucleophilic counterions include halide ions such as chloride ions and bromide ions; fluoroalkyl sulfonate ions such as triflate ions, 1,1,1-trifluoroethanesulfonate ions and nonafluorobutanesulfonate ions; aryl sulfonate ions such as tosylate ions, benzenesulfonate ions, 4-fluorobenzenesulfonate ions and 1,2,3,4,5-pentafluorobenzenesulfonate ions; alkyl sulfonate ions such as mesylate ions and butanesulfonate ions; imide ions such as bis(trifluoromethylsulfonyl)imide ions, bis(perfluoroethylsulfonyl)imide ions and bis(perfluorobutylsulfonyl)imide ions; and methide ions such as tris(trifluoromethylsulfonyl)methide ions and tris(perfluoroethylsulfonyl)methide ions.

Other examples of the non-nucleophilic counterions mentioned above include the sulfonate ion represented by the following general formula (f1-1), in which the α-position is substituted with a fluorine atom, and the sulfonate ion represented by the following general formula (f1-2), in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group.

In the above general formula (f1-1), R ³¹ is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to the hydrocarbyl group represented by R ¹¹¹ in formula (3A') described later.

In the above general formula (f1-2), R ³² is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 6 to 20 carbon atoms, and the hydrocarbyl group and hydrocarbylcarbonyl group may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl portion of the above hydrocarbyl group and hydrocarbylcarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to the hydrocarbyl group represented by R ¹¹¹ in formula (3A') described later.

Examples of monomer cations that give the repeating unit f1 include, but are not limited to, those listed below. In the following formulas, R ^A is the same as above.

Specific examples of monomer cations that give repeating units f2 or f3 include those similar to those exemplified as cations of sulfonium salts represented by general formulas (1) and (1') above.

Examples of monomer anions that give the repeating unit f2 include, but are not limited to, those listed below. In the following formula, R ^A is the same as above.

Examples of monomer anions that give the repeating unit f3 include, but are not limited to, those listed below. In the following formula, R ^A is the same as above.

The repeating units f1 to f3 described above function as acid generators. By attaching the acid generator to the polymer main chain, acid diffusion is reduced, preventing a decrease in resolution due to blurring caused by acid diffusion. Furthermore, the uniform dispersion of the acid generator improves LWR and CDU. Note that when using a base polymer containing repeating unit f, the addition of the additive-type acid generator described later can be omitted.

In the above base polymer, the content ratios of repeating units a1, a2, b, c, d, e, f1, f2, and f3 are preferably 0≦a1≦0.9, 0≦a2≦0.9, 0≦a1+a2≦0.9, 0≦b≦0.9, 0≦c≦0.9, 0≦d≦0.5, 0≦e≦0.5, 0≦f1≦0.5, 0≦f2≦0.5, 0≦f3≦0.5, and 0≦f1+f2+f3≦0.5, and preferably 0≦a1≦0.8, 0≦a2≦0.8, 0≦a1+a2≦0.8, 0 It is more preferable that ≤ b ≤ 0.8, 0 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.4, 0 ≤ e ≤ 0.4, 0 ≤ f1 ≤ 0.4, 0 ≤ f2 ≤ 0.4, 0 ≤ f3 ≤ 0.4, and 0 ≤ f1 + f2 + f3 ≤ 0.4. Even more preferable are 0 ≤ a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ a1 + a2 ≤ 0.7, 0 ≤ b ≤ 0.7, 0 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.3, 0 ≤ e ≤ 0.3, 0 ≤ f1 ≤ 0.3, 0 ≤ f2 ≤ 0.3, 0 ≤ f3 ≤ 0.3, and 0 ≤ f1 + f2 + f3 ≤ 0.3, where a1 + a2 + b + c + d + f1 + f2 + f3 + e = 1.0.

To synthesize the above base polymer, for example, the monomers that provide the repeating units described above can be polymerized by heating them in an organic solvent with a radical polymerization initiator.

Examples of organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

When copolymerizing monomers containing hydroxyl groups, the hydroxyl groups may be substituted with acetal groups that are easily deprotected by acids such as ethoxyethoxy groups during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, they may be substituted with acetyl groups, formyl groups, pivaloyl groups, etc., and then subjected to alkaline hydrolysis after polymerization.

When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene. After polymerization, the acetoxy group can be deprotected by the above-mentioned alkaline hydrolysis to obtain hydroxystyrene or hydroxyvinylnaphthalene.

For alkaline hydrolysis, ammonia water, triethylamine, etc., can be used as the base. The reaction temperature is preferably -20 to 100°C, more preferably 0 to 60°C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

The above-mentioned base polymer has a polystyrene-equivalent weight-average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30,000, determined by gel permeation chromatography (GPC) using THF as a solvent. When Mw is within this range, the heat resistance and solubility in alkaline developers of the resist film are good.

Furthermore, if the molecular weight distribution (Mw/Mn) of the above-mentioned base polymer is sufficiently narrow, there are no low-molecular-weight or high-molecular-weight polymers present, thus eliminating the risk of foreign matter being observed on the pattern or deterioration of the pattern shape after exposure. As the pattern rule becomes finer, the influence of Mw and Mw/Mn tends to increase. Therefore, to obtain a resist material suitable for fine pattern dimensions, it is preferable that the Mw/Mn of the above-mentioned base polymer be narrowly dispersed, specifically between 1.0 and 2.0, and particularly between 1.0 and 1.5.

The above base polymer may contain two or more polymers with different composition ratios, Mw, and Mw/Mn.

[Acid Generator]
The resist material of the present invention may contain an acid generator that generates a strong acid (hereinafter also referred to as an additive-type acid generator). Here, a strong acid means a compound having sufficient acidity to cause a deprotection reaction of acid-unstable groups of the base polymer in the case of a chemically amplified positive-type resist material, and a compound having sufficient acidity to cause a polarity change reaction or crosslinking reaction by an acid in the case of a chemically amplified negative-type resist material. By including such an acid generator, the sulfonium salt A described above functions as a quencher, and the resist material of the present invention can function as a chemically amplified positive-type resist material or a chemically amplified negative-type resist material.

Examples of the acid-generating agents mentioned above include compounds that generate acid in response to active light or radiation (photoacid generators). Any compound that generates acid upon irradiation with high-energy rays can be used as the photoacid generator, but those that generate sulfonic acid, imido acid, or methidic acid are preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxiimide, and oxime-O-sulfonate type acid generators. Specific examples of photoacid generators are those described in paragraphs [0122] to [0142] of Japanese Patent Publication No. 2008-111103.

Furthermore, sulfonium salts represented by the following general formula (3-1) and iodonium salts represented by the following general formula (3-2) can also be suitably used as photoacid generators.

In the above general formulas (3-1) and (3-2), R ¹⁰¹ to R ¹⁰⁵ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, preferably 1 to 20 carbon atoms, which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified as the hydrocarbyl groups represented by R ² to R ⁴ in the explanation of the above general formulas (1) and (1').

Furthermore, R ¹⁰¹ and R ¹⁰² may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, the ring may be the same as the ring that R ² and R ^{3 may bond to each other to form a ring with the sulfur atom to which they are bonded, as exemplified in the explanation of general formulas (1) and (1'} ) above.

Examples of cations of the sulfonium salt represented by the above general formula (3-1) are the same as those exemplified for the cations of the sulfonium salt represented by the above general formulas (1) and (1').

The cations of the iodonium salt represented by the above general formula (3-2) include, but are not limited to, those listed below.

In the above general formulas (3-1) and (3-2), ^Xa- is an anion selected from the following general formulas (3A) to (3D).

In the general formula (3A) above, R ^fa is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to the hydrocarbyl group represented by R ¹¹¹ in formula (3A') described later.

The anion represented by the above general formula (3A) is preferably the one represented by the following general formula (3A').

In the above general formula (3A'), R ^HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ¹¹¹ is a C1-C38 hydrocarbyl group which may contain a heteroatom. The heteroatom is preferably an oxygen atom, nitrogen atom, sulfur atom, halogen atom, etc., with oxygen atom being more preferred. The hydrocarbyl group is particularly preferably one with C6-C30, from the viewpoint of obtaining high resolution in fine pattern formation.

The hydrocarbyl group represented by R ¹¹¹ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 38 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and eicosanyl; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, Examples include cyclic saturated hydrocarbyl groups having 3 to 38 carbon atoms, such as norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, and dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms, such as allyl group and 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms, such as phenyl group, 1-naphthyl group, and 2-naphthyl group; aralkyl groups having 7 to 38 carbon atoms, such as benzyl group and diphenylmethyl group; and groups obtained by combining these.

Furthermore, some or all of the hydrogen atoms of these groups may be substituted with groups containing heteroatoms such as oxygen, sulfur, nitrogen, and halogen atoms, and some of the carbon atoms of these groups may be substituted with groups containing heteroatoms such as oxygen, sulfur, and nitrogen atoms. As a result, these groups may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, etc. Examples of hydrocarbyl groups containing heteroatoms include tetrahydrofuryl groups, methoxymethyl groups, ethoxymethyl groups, methylthiomethyl groups, acetamidomethyl groups, trifluoroethyl groups, (2-methoxyethoxy)methyl groups, acetoxymethyl groups, 2-carboxy-1-cyclohexyl groups, 2-oxopropyl groups, 4-oxo-1-adamantyl groups, and 3-oxocyclohexyl groups.

For details regarding the synthesis of sulfonium salts containing the anion represented by the above general formula (3A'), please refer to Japanese Patent Publication No. 2007-145797, Japanese Patent Publication No. 2008-106045, Japanese Patent Publication No. 2009-7327, Japanese Patent Publication No. 2009-258695, etc. Furthermore, sulfonium salts described in Japanese Patent Publication No. 2010-215608, Japanese Patent Publication No. 2012-41320, Japanese Patent Publication No. 2012-106986, Japanese Patent Publication No. 2012-153644, etc., are also suitably used.

Examples of anions represented by the above general formula (3A) include those similar to those exemplified as anions represented by formula (1A) in Japanese Patent Publication No. 2018-197853.

In the above general formula (3B), R ^fb1 and R ^fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified as the hydrocarbyl group represented by R ¹¹¹ in the above general formula (3A'). R ^fb1 and R ^fb2 are preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. Furthermore, R ^fb1 and R ^fb2 may bond to each other to form a ring with the group to which they are bonded ( _-CF2 - _SO2 -N ^-- _SO2 - _CF2- ), and in this case, the group obtained by the bonding of R ^fb1 and R ^fb2 is preferably a fluorinated ethylene group or a fluorinated propylene group.

In the above general formula (3C), R ^fc1 , R ^fc2 , and R ^fc3 are each independently a C1-C40 hydrocarbyl group which may contain a fluorine atom or a heteroatom. The above hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified as the hydrocarbyl group represented by R ¹¹¹ in the above general formula (3A'). R ^fc1 , R ^fc2 , and R ^fc3 are preferably a fluorine atom or a C1-C4 linear fluorinated alkyl group. Furthermore, R ^fc1 and R ^fc2 may bond to each other to form a ring with the group to which they bond ( _-CF2 - _SO2 -C ^-- _SO2 - _CF2- ), and in this case, the group obtained by the bonding of R ^fc1 and R ^fc2 to each other is preferably a fluorinated ethylene group or a fluorinated propylene group.

In the above general formula (3D), R ^fd is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to the hydrocarbyl group represented by R ¹¹¹ in the above general formula (3A').

The synthesis of sulfonium salts containing the anion represented by the above general formula (3D) is detailed in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2014-133723.

Examples of anions represented by the above general formula (3D) include those similar to those exemplified as anions represented by formula (1D) in Japanese Patent Publication No. 2018-197853.

Furthermore, the photoacid generator containing the anion represented by formula (3D) does not have a fluorine atom at the α-position of the sulfo group, but due to the presence of two trifluoromethyl groups at the β-position, it possesses sufficient acidity to cleave acid-unstable groups in the base polymer. Therefore, it can be used as a photoacid generator.

As a photoacid generator, one represented by the following general formula (4) can also be suitably used.

In the above general formula (4), R ²⁰¹ and R ²⁰² are each independently a C1-C30 hydrocarbyl group which may contain a halogen atom or a heteroatom. R ²⁰³ is a C1-C30 hydrocarbylene group which may contain a heteroatom. Furthermore, any two of R ²⁰¹ , R ²⁰² , and R ²⁰³ may bond to each other to form a ring with the sulfur atom to which they are bonded. In this case, the ring is similar to the one exemplified in the explanation of the above general formulas (1) and (1') as a ring which can be formed when R ² and R ³ bond to each other with the sulfur atom to which they are bonded.

The hydrocarbyl groups represented by R ²⁰¹ and R ²⁰² may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, and tricyclo[5.2.1.0 ^2,6 Examples include cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as decanyl and adamantyl groups; aryl groups having 6 to 30 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, tert-butylnaphthyl, and anthracenyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the carbon atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, etc.

The hydrocarbylene group represented by R ²⁰³ may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C30 alkanediyl groups such as methanediyl, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl, dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl, pentadecane-1,15-diyl, hexadecane-1,16-diyl, heptadecane-1,17-diyl; cyclopentanediyl, cyclohex Examples include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as xanediyl group, norbornanediyl group, and adamantanediyl group; arylene groups having 6 to 30 carbon atoms, such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, and tert-butylnaphthylene group; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the carbon atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, etc. Among the heteroatoms, oxygen atoms are preferred.

In the general formula (4) above, L ^A is a C1-C20 hydrocarbylene group which may contain a single bond, an ether bond, or a heteroatom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified as the hydrocarbylene group represented by R ²⁰³ .

In the above general formula (4), X ^A , X ^B , X ^C , and X ^D are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. However, at least one of X ^A , X ^B , X ^C , and X ^D is a fluorine atom or a trifluoromethyl group.

In the general formula (4) above, d is an integer between 0 and 3.

The photoacid generator represented by the above general formula (4) is preferably the one represented by the following general formula (4').

In the above general formula (4'), L ^A is the same as above. R ^HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. R ³⁰¹ , R ³⁰² , and R ³⁰³ are each independently a C1 to C20 hydrocarbyl group which may contain a hydrogen atom or a heteroatom. The above hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is the same as the hydrocarbyl group exemplified as R ¹¹¹ in formula (3A'). x and y are each independently integers from 0 to 5, and z is an integer from 0 to 4.

Examples of photoacid generators represented by the above general formula (4) include those similar to those exemplified as photoacid generators represented by formula (2) in Japanese Patent Publication No. 2017-026980.

Among the above photoacid generators, those containing anions represented by the general formula (3A') or (3D) are particularly preferred because they exhibit low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (4') are particularly preferred because they exhibit extremely low acid diffusion.

As the above-mentioned photoacid generator, sulfonium salts or iodonium salts containing an anion having an aromatic ring substituted with an iodine atom or a bromine atom can also be used. Examples of such salts are those represented by the following general formulas (5-1) or (5-2).

In the general formulas (5-1) and (5-2) above, p is an integer satisfying 1 ≤ p ≤ 3. q and r are integers satisfying 1 ≤ q ≤ 5, 0 ≤ r ≤ 3, and 1 ≤ q + r ≤ 5. q is preferably an integer satisfying 1 ≤ q ≤ 3, and more preferably 2 or 3. r is preferably an integer satisfying 0 ≤ r ≤ 2.

In the above general formulas (5-1) and (5-2), X ^BI is an iodine atom or a bromine atom, and when p and/or q are 2 or more, they may be the same or different from each other.

In the above general formulas (5-1) and (5-2), ^L1 is a saturated hydrocarbylene group having 1 to 6 carbon atoms, which may contain a single bond, an ether bond, or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

In the above general formulas (5-1) and (5-2), ^L2 is a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and a (p+1) valent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, a halogen atom, or a nitrogen atom.

In the above general formulas (5-1) and (5-2), R ⁴⁰¹ is a C1-C20 hydrocarbyl group, a C1-C20 hydrocarbyloxy group, a C2-C20 hydrocarbylcarbonyl group, a C2-C20 hydrocarbyloxycarbonyl group, a C2-C20 hydrocarbylcarbonyloxy group, a C2-C20 hydrocarbylcarbonyloxy group, a C2-C20 hydrocarbylcarbonyloxy group, or a C1-C20 hydrocarbylsulfonyloxy group, or -N(R ^401A )(R ^401B ), -N(R 401C)-C ⁽ =O)-R ^401D or -N(R ^401C )-C(=O)-O-R ^401D . R ^401A and R ^401B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R ^401C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. ^{R 401D} is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The above aliphatic hydrocarbyl groups may be saturated or unsaturated, and may be linear, branched, or cyclic. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyloxycarbonyl group, saturated hydrocarbylcarbonyl group, and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. When p and/or r is 2 or more, each R ⁴⁰¹ may be the same or different from one another.

Of these, R ⁴⁰¹ is preferably a hydroxyl group, -N(R ^401C )-C(=O)-R ^401D , -N(R ^401C )-C(=O)-O-R ^401D , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, etc.

In the above general formulas (5-1) and (5-2), Rf ¹ to Rf ⁴ are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of these is a fluorine atom or a trifluoromethyl group. Also, Rf ¹ and Rf ² may combine to form a carbonyl group. In particular, it is preferable that both Rf ³ and Rf ⁴ are fluorine atoms.

In the above general formulas (5-1) and (5-2), R ⁴⁰² to R ⁴⁰⁶ are each independently a C1 to C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. The above hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include those similar to those exemplified as the hydrocarbyl groups represented by R ² to R ³ in the explanation of the above general formulas (1) and (1'). Furthermore, some or all of the hydrogen atoms of these groups may be substituted with a hydroxyl group, carboxyl group, halogen atom, cyano group, nitro group, mercapto group, sultone ring, sulfone group, or sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond, or sulfonic acid ester bond. In addition, R ⁴⁰² and R ⁴⁰³ may bond to each other to form a ring with the sulfur atom to which they are bonded. In this case, the above-mentioned ring is similar to the one exemplified in the explanation of formulas (1) and (1') as a ring that can be formed when ^R2 and ^R3 bond to each other and together with the sulfur atom to which they are bonded.

Examples of cations for the sulfonium salt represented by the above general formula (5-1) are the same as those exemplified for the sulfonium salts represented by the above general formulas (1) and (1'). Similarly, examples of cations for the iodonium salt represented by the above general formula (5-2) are the same as those exemplified for the iodonium salt represented by formula (3-2).

The anions of the onium salt represented by the above general formula (5-1) or (5-2) include, but are not limited to, those listed below. In the following formulas, X ^BI is the same as above.

When the resist material of the present invention contains an additive-type acid generator, its content is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The resist material of the present invention can function as a chemically amplified resist material by the base polymer containing any of the repeating units f1 to f3 and/or by the inclusion of the additive-type acid generator.

[Organic solvents]
The resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the components described above and the components described later. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs [0144] to [0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol Examples include ethers such as monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; and lactones such as γ-butyrolactone.

In the resist material of the present invention, the content of the above-mentioned organic solvent is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The above-mentioned organic solvent may be used alone or as a mixture of two or more types.

[Other ingredients]
In addition to the components described above, the resist material of the present invention may also contain surfactants, dissolution inhibitors, crosslinking agents, quenchers other than sulfonium salt A (hereinafter referred to as "other quenchers"), water-repellency enhancers, acetylene alcohols, and the like.

Examples of the surfactants mentioned above include those described in paragraphs [0165] to [0166] of Japanese Patent Publication No. 2008-111103. By adding a surfactant, the coatability of the resist material can be further improved or controlled. When the resist material of the present invention contains the surfactant, its content is preferably 0.0001 to 10 parts by mass per 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more types.

When the resist material of the present invention is of the positive type, the difference in dissolution rate between the exposed and unexposed areas can be further increased by incorporating a dissolution inhibitor, thereby further improving the resolution. Examples of such dissolution inhibitors include compounds having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, and containing two or more phenolic hydroxyl groups in the molecule, in which the hydrogen atoms of the phenolic hydroxyl groups are substituted with acid-unstable groups in a proportion of 0 to 100 mol% overall, or compounds containing a carboxyl group in the molecule, in which the hydrogen atoms of the carboxyl group are substituted with acid-unstable groups in an average proportion of 50 to 100 mol overall. Specifically, examples include compounds in which the hydrogen atoms of the hydroxyl or carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid are substituted with acid-unstable groups, as described, for example, in paragraphs [0155] to [0178] of Japanese Patent Application Publication No. 2008-122932.

When the resist material of the present invention is of the positive type and contains the above-mentioned dissolution inhibitor, the content is preferably 0 to 50 parts by mass, and more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The above-mentioned dissolution inhibitor may be used alone or in combination of two or more types.

On the other hand, if the resist material of the present invention is negative type, a negative pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluryl compounds, urea compounds, isocyanate compounds, azide compounds, or compounds containing double bonds such as alkenyloxy groups, substituted with at least one group selected from methylol, alkoxymethyl, and acyloxymethyl groups. These may be used as additives or introduced as pendant groups into the polymer side chains. Compounds containing hydroxyl groups can also be used as crosslinking agents.

Examples of the epoxy compounds mentioned above include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

Examples of the above-mentioned melamine compounds include hexamethylmelamine, hexamethoxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are methoxymethylated or mixtures thereof, hexamethoxyethylmelamine, hexaacyloxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are acyloxymethylated or mixtures thereof.

Examples of the above-mentioned guanamine compounds include tetramethylolguanamine, tetramethoxymethylguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated, or mixtures thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated, or mixtures thereof.

Examples of the glycoluryl compounds mentioned above include tetramethylol glycoluryl, tetramethoxyglycoluryl, tetramethoxymethyl glycoluryl, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are methoxymethylated or mixtures thereof, and compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are acyloxymethylated or mixtures thereof.

Examples of the above-mentioned urea compounds include tetramethylolurea, tetramethoxymethylurea, compounds in which one to four methylol groups of tetramethylolurea are methoxymethylated, or mixtures thereof, and tetramethoxyethylurea.

Examples of the above-mentioned isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

Examples of the above-mentioned azide compounds include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

Examples of compounds containing the above-mentioned alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

When the resist material of the present invention is of the negative type and contains the above-mentioned crosslinking agent, the content is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The above-mentioned crosslinking agent may be used alone or in combination of two or more types.

Other quenchers mentioned above include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, or tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, etc. Particularly preferred are primary, secondary, and tertiary amine compounds described in paragraphs [0146] to [0164] of Japanese Patent Publication No. 2008-111103, especially amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent Publication No. 3790649. By adding such basic compounds, for example, the diffusion rate of acid in the resist film can be further suppressed, or its shape can be corrected.

Furthermore, other quenchers include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids and carboxylic acids whose α-position is not fluorinated, as described in Japanese Patent Publication No. 2008-158339. While α-fluorinated sulfonic acids, imido acids, or methidic acids are necessary for deprotecting the acid-unstable group of carboxylic acid esters, salt exchange with an onium salt whose α-position is not fluorinated releases the α-fluorinated sulfonic acid or carboxylic acid. Since α-fluorinated sulfonic acids and carboxylic acids do not undergo deprotection reactions, they function as quenchers.

Other quenchers include the polymer-type quencher described in Japanese Patent Publication No. 2008-239918. This enhances the rectangularity of the resist pattern by oriented on the resist film surface. Polymer-type quenchers also have the effect of preventing pattern film thinning and rounding of the pattern top when a protective film for immersion lithography is applied.

When the resist material of the present invention contains other quenchers, their content is preferably 0 to 5 parts by mass, and more preferably 0 to 4 parts by mass, per 100 parts by mass of the base polymer. The other quenchers may be used individually or in combination of two or more.

The above-mentioned water-repellency improving agent improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred water-repellency improving agents include polymers containing alkyl fluoride, polymers containing 1,1,1,3,3,3-hexafluoro-2-propanol residues of a specific structure, and those exemplified in Japanese Patent Publication No. 2007-297590 and Japanese Patent Publication No. 2008-111103 are more preferred. The above-mentioned water-repellency improving agent needs to be soluble in an alkaline developer or an organic solvent developer. The water-repellency improving agent having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residues described above has good solubility in the developer. As a water-repellency improving agent, polymers containing repeating units including amino groups or amine salts are highly effective in preventing acid evaporation during post-exposure baking (PEB) and thus preventing poor hole pattern opening after development. When the chemically amplified resist material of the present invention contains the above-mentioned water-repellency improving agent, its content is preferably 0 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The above-mentioned water-repellency improving agent may be used alone or in combination of two or more types.

Examples of the acetylene alcohols mentioned above include those described in paragraphs [0179] to [0182] of Japanese Patent Publication No. 2008-122932. When the chemical amplification resist material of the present invention contains the above-mentioned acetylene alcohols, the content is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The above-mentioned acetylene alcohols may be used individually or in combination of two or more types.

[Pattern Formation Method]
When the resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method may include a step of forming a resist film on a substrate using the chemically amplified resist material described above, a step of exposing the resist film with high-energy rays, and a step of developing the exposed resist film using a developer.

First, the resist material of the present invention is applied to a substrate for integrated circuit manufacturing (Si, _SiO₂ , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, _MoSi₂ , _SiO₂ , etc.) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating, so that the coating film thickness is 0.01 to 2 μm. This is then pre-baked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

Next, the resist film is exposed using high-energy beams. Examples of high-energy beams include ultraviolet light, far ultraviolet light, electron beam (EB), extreme ultraviolet (EUV) with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When using ultraviolet light, far ultraviolet light, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, or synchrotron radiation as the high-energy beams, the exposure is preferably about 1 to 200 mJ/ ^cm² , more preferably about 10 to 100 mJ/ ^cm² , either directly or using a mask to form the desired pattern. When using electron beams as the high-energy beams, the exposure is preferably about 0.1 to 300 μC/ ^cm² , more preferably about 0.5 to 200 μC/ ^cm² , and the pattern is drawn either directly or using a mask to form the desired pattern. Furthermore, the resist material of the present invention is particularly suitable for fine patterning using high-energy rays, including KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, gamma rays, and synchrotron radiation. In particular, it is preferable to use KrF excimer laser light, ArF excimer laser light, EB, or EUV with a wavelength of 3 to 15 nm, and is especially suitable for fine patterning using EB or EUV.

After exposure, PEB (Photopolymer Exposure) may be performed on a hot plate or in an oven, preferably at 30-150°C for 10 seconds to 30 minutes, more preferably at 50-120°C for 30 seconds to 20 minutes, or it may be omitted.

After exposure or PEB (Photobleached Embossing), the exposed resist film is developed using a developer solution containing 0.1 to 10% by mass, preferably 2 to 5% by mass, of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide. The development is performed for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, using conventional methods such as the dip method, puddle method, or spray method, thereby forming the desired pattern. In the case of positive-type resist materials, the areas irradiated with light dissolve in the developer solution, while the unexposed areas remain insoluble, forming the desired positive-type pattern on the substrate. In the case of negative-type resist materials, the opposite occurs: the areas irradiated with light become insoluble in the developer solution, while the unexposed areas dissolve.

Negative patterns can also be obtained by organic solvent development using positive-type resist materials containing a base polymer with acid-unstable groups. The developers used in this process include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotate, ethyl crotate, Examples include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenyl acetate, and 2-phenylethyl acetate. These organic solvents may be used individually or in combination of two or more.

At the end of development, rinsing is performed. A solvent that mixes with the developer but does not dissolve the resist film is preferred as the rinsing solution. Preferred solvents include alcohols with 3 to 10 carbon atoms, ether compounds with 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents with 6 to 12 carbon atoms.

The above C3-C10 alcohols include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, Examples include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

Examples of the above-mentioned ether compounds having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

Examples of alkanes with 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Examples of alkenes with 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Examples of alkynes with 6 to 12 carbon atoms include hexine, heptine, and octine.

Examples of the above-mentioned aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

Rinsing can reduce the occurrence of resist pattern deformation and defects. However, rinsing is not always necessary; omitting rinsing can reduce solvent usage.

The developed hole patterns and trench patterns can also be shrunk using thermal flow, RELACS, or DSA techniques. A shrinking agent is applied to the hole pattern, and during baking, the diffusion of an acid catalyst from the resist film causes crosslinking of the shrinking agent on the surface of the resist film, causing the shrinking agent to adhere to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds, during which excess shrinking agent is removed and the hole pattern is reduced in size.

The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

The structures of quenchers Q-1 to Q-28 used in the resist material are shown below.

[Synthesis Example] Synthesis of Base Polymers (Polymers 1-5) Each monomer was combined and copolymerized in THF, a solvent, crystallized in methanol, and after repeated washing with hexane, isolated and dried to obtain base polymers (Polymers 1-5) with the compositions shown below. The composition of the obtained base polymers was confirmed by ^1H -NMR, and Mw and Mw/Mn were confirmed by GPC (solvent: THF, standard: polystyrene).

[Examples 1-32, Comparative Examples 1-4] Preparation and Evaluation of Resist Materials (1) Preparation of Resist Materials Resist materials were prepared by dissolving each component in the compositions shown in Tables 1 and 2, and filtering the solutions through a 0.2 μm size filter. The resist materials of Examples 1-20, 22-32, and Comparative Examples 1-3 were positive type, while the resist materials of Example 21 and Comparative Example 4 were negative type.

In Tables 1 and 2, the components are as follows:
• Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)
DAA (Diacetone Alcohol)
EL (ethyl lactate)

• Acid generators: PAG-1 to PAG-5

Blend Quencher: bQ-1, bQ-2

• Comparative quenchers: cQ-1, cQ-2, cQ-3

(2) EUV Lithography Evaluation Each resist material shown in Tables 1 and 2 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43 mass%) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. A resist film with a thickness of 60 nm was then prepared by pre-baking at 100°C for 60 seconds using a hot plate. Next, the resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9/0.6, quadruple pole illumination, wafer dimensions pitch 44 nm, hole pattern mask with +20% bias). PEB was performed on a hot plate for 60 seconds at the temperatures shown in Tables 1 and 2, and development was performed with a 2.38 mass% TMAH aqueous solution for 30 seconds. Hole patterns with dimensions of 22 nm were obtained in Examples 1-20, 22-32, and Comparative Examples 1-3, and dot patterns with dimensions of 22 nm were obtained in Example 21 and Comparative Example 4.
Using a length-measuring SEM (CG6300) manufactured by Hitachi High-Tech Corporation, the exposure amount at which a hole or dot dimension of 22 nm was formed was measured and defined as the sensitivity. The dimensions of 50 holes or dots at this point were also measured, and the CDU (Critical Duct) was defined as three times the standard deviation (σ) calculated from these results (3σ). The results are shown in Tables 1 and 2.

The results shown in Tables 1 and 2 indicate that the resist material of the present invention, containing one or more of the following as a quencher: substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid sulfonium salts, and/or substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid sulfonium salts, substituted or unsubstituted hydroxy(difluoromethoxy)benzoic acid sulfonium salts, substituted or unsubstituted hydroxy(difluoromethylthio)benzoic acid sulfonium salts, 2- or 3-di or trifluoromethoxybenzoic acid sulfonium salts, and 2- or 3-di or trifluoromethylthiobenzoic acid sulfonium salts, exhibited high sensitivity and improved CDU (Critical Duplication Unit).

This specification includes the following embodiments:
[1] As a quencher,
A resist material characterized by comprising a substituted or unsubstituted sulfonium salt of hydroxy(trifluoromethoxy)benzoic acid, and/or a substituted or unsubstituted sulfonium salt of hydroxy(trifluoromethylthio)benzoic acid.
[2]: The resist material according to [1] above, characterized in that the sulfonium salt of the substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid, and/or the sulfonium salt of the substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid is represented by the following general formula (1).
(In the formula, ^R1 is a hydrogen atom, or a group selected from linear, branched, or cyclic alkyl, alkoxy, alkoxycarbonyl, or acyl groups having 1 to 15 carbon atoms, or alkenyl or alkynyl groups having 2 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may also be an acid-unstable group. X is an oxygen atom or a sulfur atom. m and n are 1 or 2, respectively. ^R2 to ^R4 are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. ^R2 and ^R3 may also be bonded to each other to form a ring with the sulfur atom to which they are bonded.)
[3] As a quencher,
A resist material characterized by containing one or more of the following: a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethoxy)benzoic acid, a substituted or unsubstituted sulfonium salt of hydroxy(difluoromethylthio)benzoic acid, a sulfonium salt of 2- or 3-di or trifluoromethoxybenzoic acid, and a sulfonium salt of 2- or 3-di or trifluoromethylthiobenzoic acid.
[4]: The resist material according to [3] above, characterized in that one or more of the substituted or unsubstituted sulfonium salts of hydroxy(difluoromethoxy)benzoic acid, substituted or unsubstituted sulfonium salts of hydroxy(difluoromethylthio)benzoic acid, sulfonium salts of 2- or 3-di or trifluoromethoxybenzoic acid, and sulfonium salts of 2- or 3-di or trifluoromethylthiobenzoic acid are represented by the following general formula (1').
(In the formula, R ^1' is a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted amino group, or a linear, branched, or cyclic alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, alkenyloxy group, or alkynyloxy group having 1 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may be an acid-unstable group. However, if R ¹ ' is a _hydrogen atom, the substitution position of the C-X- group is at position 2 or 3. _p is 0 or 1, q is 2 or 3. X is an oxygen atom or a sulfur atom. m and n are 1 or 2, respectively. ^{R 2} to R ⁴ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ² and R ( ³ may bond to each other, forming a ring with the sulfur atom to which they are bonded.)
[5]: The resist material according to any one of [1] to [4] above, further characterized by containing an acid generator that generates acid.
[6]: The resist material according to [5] above, characterized in that the acid generating agent generates sulfonic acid, imido acid, or methidoic acid.
[7]: The resist material according to any one of [1] to [6] above, further characterized in that it contains an organic solvent.
[8]: The resist material according to any one of [1] to [7], further characterized in that it contains a base polymer.
[9]: The resist material according to [8], characterized in that the base polymer includes repeating units represented by the following general formula (a1) and/or repeating units represented by the following general formula (a2).
(In the formula, R ^A is independently a hydrogen atom or a methyl group. ^{Y 1} is a carbon-1 to carbon-12 linking group containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond and a lactone ring. ^{Y 2} is a single bond or an ester bond. ^{Y 3} is a single bond, an ether bond or an ester bond. ^{R 11} and R ¹² are independently acid-unstable groups. ^{R 13} is a fluorine atom, a trifluoromethyl group, a cyano group, or a carbon-1 to carbon-6 saturated hydrocarbyl group. R ¹⁴ is a single bond or a carbon-1 to carbon-6 alkanediyl group, some of which carbon atoms may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer from 0 to 4, where 1 ≤ a + b ≤ 5.)
[10]: The resist material according to [9] above, characterized in that the resist material is a chemically amplified positive resist material.
[11]: The resist material according to [8] above, characterized in that the base polymer does not contain acid-unstable groups.
[12]: The resist material according to [11], characterized in that the resist material is a chemically amplified negative resist material.
[13]: The resist material according to any one of [8] to [12], characterized in that the base polymer further comprises at least one selected from repeating units represented by the following general formulas (f1) to (f3).
(In the formula, R ^A is independently a hydrogen atom or a methyl group. Z ¹ is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z ^11- , -C(=O)-O-Z ^11- or -C(=O)-NH-Z ^11- . Z ¹¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. ^{Z 2} is a single bond or an ester bond. Z ³ is a single bond, -Z ³¹ -C(=O)-O-, -Z ³¹ -O- or -Z ³¹ -O-C(=O)-. Z ³¹ is a C1-C12 hydrocarbylene group, a phenylene group, or a C7-C18 group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. ^Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. ^Z5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O- ^Z51- , -C(=O)-O- ^Z51- , or -C(=O)-NH- ^Z51- . ⁵¹ is a phenylene group substituted with an aliphatic hydrocarbylene group, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group having 1 to 15 carbon atoms, or a combination thereof, and may also contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and/or a hydroxyl group. R ²¹ to R ²⁸ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ²³ and R ²⁴ or R ²⁶ and R ²⁷ may bond to each other to form a ring with the sulfur atom to which they are bonded. ^M- is a non-nucleophilic counterion.
[14]: The resist material according to any one of [1] to [13], further characterized by containing a surfactant.
[15]: A pattern forming method characterized by comprising the steps of forming a resist film on a substrate using a resist material described in any of [1] to [14] above, exposing the resist film with a high-energy beam, and developing the exposed resist film using a developer.
[16]: The pattern formation method according to [15], characterized in that the high-energy beam is KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

Furthermore, the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical concept described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims (17)

As a quencher,
A resist material characterized by comprising a sulfonium salt of substituted or unsubstituted hydroxy(trifluoromethoxy)benzoic acid, and/or a sulfonium salt of substituted or unsubstituted hydroxy(trifluoromethylthio)benzoic acid, represented by the following general formula (1) .
(In the formula, R1 ^is a hydrogen atom, or a group selected from linear, branched, or cyclic alkyl, alkoxy, alkoxycarbonyl, or acyl groups having 1 to 15 carbon atoms, or alkenyl or alkynyl groups having 2 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may also be an acid-unstable group. X is an oxygen atom or a sulfur atom. m and n are 1 or 2, respectively. ^R2 to R4 ^are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. R2 and R3 may also ^be bonded ^to each other to form a ring with the sulfur atom to which they are bonded.) As a quencher,
A resist material characterized by containing one or more of the following, represented by the general formula (1'): a sulfonium salt of substituted or unsubstituted hydroxy(difluoromethoxy)benzoic acid, a sulfonium salt of substituted or unsubstituted hydroxy(difluoromethylthio)benzoic acid, a sulfonium salt of 2- or 3-di or trifluoromethoxybenzoic acid, and a sulfonium salt of 2- or 3-di or trifluoromethylthiobenzoic acid.
(In the formula, R ^1' is a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted amino group, or a linear, branched, or cyclic alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, alkenyloxy group, or alkynyloxy group having 1 to 15 carbon atoms. The group may have a halogen atom, a carbonyl group, an ether bond, a substituted or unsubstituted aryl group, or a hydroxyl group, and may be an acid-unstable group. However, if R ¹ ' is a _hydrogen atom, the substitution position of the C-X- group is at position 2 or 3. _p is 0 or 1, q is 2 or 3. X is an oxygen atom or a sulfur atom. m and n are 1 or 2, respectively. R ² to R ⁴ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ² and R ( ³ may bond to each other, forming a ring with the sulfur atom to which they are bonded.) Furthermore, the resist material according to claim 1 is characterized by containing an acid generator that produces acid. The resist material according to claim 3 , characterized in that the acid generating agent generates sulfonic acid, imido acid, or methido acid. Furthermore, the resist material according to claim 1 is characterized by containing an organic solvent. Furthermore, the resist material according to claim 3 is characterized in that it contains an organic solvent. Furthermore, the resist material according to claim 1 is characterized by containing a base polymer. Furthermore, the resist material according to claim 3 , characterized in that it further contains a base polymer. Furthermore, the resist material according to claim 5 is characterized in that it further contains a base polymer. The resist material according to claim 7 , characterized in that the base polymer includes repeating units represented by the following general formula (a1) and/or repeating units represented by the following general formula (a2).
(In the formula, R ^A is independently a hydrogen atom or a methyl group. ^{Y 1} is a carbon-1 to carbon-12 linking group containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond and a lactone ring. ^{Y 2} is a single bond or an ester bond. ^{Y 3} is a single bond, an ether bond or an ester bond. ^{R 11} and R ¹² are independently acid-unstable groups. ^{R 13} is a fluorine atom, a trifluoromethyl group, a cyano group, or a carbon-1 to carbon-6 saturated hydrocarbyl group. R ¹⁴ is a single bond or a carbon-1 to carbon-6 alkanediyl group, some of which carbon atoms may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer from 0 to 4, where 1 ≤ a + b ≤ 5.) The resist material according to claim 10 , characterized in that the resist material is a chemically amplified positive-type resist material. The resist material according to claim 7 , characterized in that the base polymer does not contain acid-unstable groups. The resist material according to claim 12 , characterized in that the resist material is a chemically amplified negative resist material. The resist material according to claim 7 , characterized in that the base polymer further comprises at least one selected from repeating units represented by the following general formulas (f1) to (f3).
(In the formula, R ^A is independently a hydrogen atom or a methyl group. Z ¹ is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z ^11- , -C(=O)-O-Z ^11- or -C(=O)-NH-Z ^11- . Z ¹¹ is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. ^{Z 2} is a single bond or an ester bond. Z ³ is a single bond, -Z ³¹ -C(=O)-O-, -Z ³¹ -O- or -Z ³¹ -O-C(=O)-. Z ³¹ is a C1-C12 hydrocarbylene group, a phenylene group, or a C7-C18 group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. ^Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. ^Z5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O- ^Z51- , -C(=O)-O- ^Z51- , or -C(=O)-NH- ^Z51- . ⁵¹ is a phenylene group substituted with an aliphatic hydrocarbylene group, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group having 1 to 15 carbon atoms, or a combination thereof, and may also contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and/or a hydroxyl group. R ²¹ to R ²⁸ are each independently a hydrocarbyl group having 1 to 25 carbon atoms, which may contain a halogen atom or a heteroatom. Also, R ²³ and R ²⁴ or R ²⁶ and R ²⁷ may bond to each other to form a ring with the sulfur atom to which they are bonded. ^M- is a non-nucleophilic counterion. Furthermore, the resist material according to claim 1 is characterized by containing a surfactant. A pattern forming method characterized by comprising the steps of: forming a resist film on a substrate using a resist material according to any one of claims 1 to 15 ; exposing the resist film with a high-energy beam; and developing the exposed resist film using a developer. The pattern formation method according to claim 16 , characterized in that the high-energy beam used is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.