Onium salt, resist composition, and pattern formation method

Abstract

This invention provides a chemically amplified resist composition that exhibits excellent LWR and resolution in far-ultraviolet lithography and EUV lithography, and can suppress resist pattern deformation, an onium salt used therein, and a pattern formation method using the resist composition. [Solution] An onium salt represented by the following formula (1). TIFF2026062943000253.tif35136

Description

[Technical Field]

[0001] The present invention relates to onium salts, resist compositions, and pattern forming methods. [Background technology]

[0002] 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. As a cutting-edge 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 the following-generation 2nm node devices.

[0003] As miniaturization progresses, image blurring due to acid diffusion is becoming a problem. To ensure resolution in fine patterns with dimensions of 45 nm or larger, it has been suggested that controlling acid diffusion is important, in addition to improving the dissolution contrast as has been conventionally proposed (Non-Patent Literature 1). However, since chemically amplified resist compositions 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.

[0004] The triangle trade-off relationship between sensitivity, resolution, and edge roughness (LER, LWR) is shown. To improve resolution, it is necessary to suppress acid diffusion, but as the acid diffusion distance decreases, sensitivity decreases.

[0005] Adding an acid generator that produces bulky acids is effective in suppressing acid diffusion. Therefore, it has been proposed to include repeating units derived from onium salts having polymerizable unsaturated bonds in 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.

[0006] The relationship between sensitivity, resolution, and edge roughness is shown as a triangle trade-off. To improve resolution, it is necessary to suppress acid diffusion, but as the acid diffusion distance decreases, sensitivity decreases.

[0007] Furthermore, various studies have been conducted on quenchers (acid diffusion control agents). Various amines are mainly used as quenchers, but there are many issues that need improvement in terms of line with roughness (LWR), which is an indicator of pattern roughness, and pattern shape. Studies using weak onium acid salts as quenchers have also been reported. For example, Patent Document 1 states that patterns with low roughness can be formed by using a compound that generates a carboxylic acid with a boiling point of 150°C or higher. Patent Document 2 states that sensitivity, resolution, and exposure margin were improved by adding ammonium sulfonate salt or ammonium carboxylate salt. Patent Document 3 states that a KrF or electron beam (EB) lithography resist composition containing a photoacid generator that generates a fluorine atom-containing carboxylic acid has excellent resolution and improved process tolerance such as exposure margin and depth of focus. Patent Document 4 describes a positive-type photosensitive composition for ArF excimer laser exposure containing an onium carboxylate salt. Patent Document 5 describes an onium salt of fluoroalkanesulfonamide, which is a weak onium acid salt. However, even when using this, the LWR (low wall thickness) and resolution, which indicate the roughness of the pattern, are insufficient in generations where ultrafine processing using ArF lithography and ArF immersion lithography is required, and further development of a weak onium acid salt with excellent quenching function has been desired. Patent Document 6 also describes an onium salt of α,α-difluorocarboxylic acid as an onium carboxylic acid salt. Even when using this, the acidity of the carboxylic acid after proton exchange with a strong acid is not sufficiently low, so it can act as an acid generator in some cases. Therefore, the quenching ability is low, and the LWR and resolution are not satisfactory. Furthermore, in EUV lithography, which has seen remarkable development in recent years, there have been reports of the use of onium aromatic carboxylic acid salts, which were not actively applied in ArF lithography.

[0008] Furthermore, onium carboxylate salts containing nitrogen-containing structures within the same molecule have also been reported. Patent documents 7-9 describe onium carboxylate salts having nitrogen-containing heterocyclic compounds such as indole and indoline, and piperidinecarboxylic acid structures, while patent document 10 describes onium carboxylate salts having aminobenzoic acid structures, and patent document 11 describes onium carboxylate salts having amide bonds. Although these also act as quenchers, aromatic amines and amide bonds are not highly basic, so their acid diffusion control ability is insufficient, and piperidinecarboxylic acid is extremely water-soluble, presenting many challenges for industrial production.

[0009] These series of weak acid onium salts function as quenchers because, upon exposure, strong acids (sulfonic acids) generated from other photoacid generators exchange with the weak acid onium salts, forming weak acids and strong acid onium salts. This replaces highly acidic strong acids (α,α-difluorosulfonic acid) with weak acids (alkanesulfonic acids, carboxylic acids, etc.), thereby suppressing the acid elimination reaction of acid-unstable groups and reducing (controlling) the acid diffusion distance. However, in recent years, with increasing miniaturization, particularly in EUV lithography, resist compositions using these weak acid onium salts have not been able to satisfy the required resolution, roughness, depth of field, etc. When using alkanesulfonates, the acidity is not sufficiently low, resulting in low quenching ability. In the case of carboxylic acid salts, not only is the aforementioned performance insufficient, but their high hydrophilicity leads to a high affinity for alkaline developers, causing swelling by drawing the developer into the exposed area. In particular, when forming fine line patterns, this swelling poses a problem as it causes the resist pattern to collapse. To meet the demands for further miniaturization, there is a need to develop a quencher that has good sensitivity, excellent acid diffusion control capabilities, and suppresses the collapse of the resist pattern due to swelling caused by alkaline developer. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 11-125907 [Patent Document 2] Japanese Patent Application Publication No. 11-327143 [Patent Document 3] Japanese Patent Publication No. 2001-281849 [Patent Document 4] Patent No. 4226803 [Patent Document 5] Japanese Patent Publication No. 2012-108447 [Patent Document 6] Japanese Patent Publication No. 2015-54833 [Patent Document 7] Patent No. 6217561 [Patent Document 8] Patent No. 6874738 [Patent Document 9] Patent No. 6512049 [Patent Document 10] Patent No. 6323302 [Patent Document 11] International Publication No. 2019 / 087626 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention has been made in view of the above circumstances, and aims to provide a chemically amplified resist composition that exhibits excellent LWR and resolution in far ultraviolet lithography and EUV lithography, and can suppress resist pattern deformation, an onium salt used therein, and a pattern formation method using the resist composition. [Means for solving the problem]

[0012] As a result of diligent research to achieve the above objective, the present inventors have found that a resist composition containing an onium salt having a nitrogen atom-containing aliphatic heterocycle and an aromatic carboxylic acid structure as a quencher exhibits excellent resolution of the resist film, low LWR, and suppresses swelling during development, making it extremely effective for precise microfabrication, leading to the present invention.

[0013] That is, the present invention provides the following onium salt, resist composition, and pattern forming method. 1. An onium salt represented by the following formula (1). [Chemical formula] [In the formula, n1 is an integer of 0 or 1. n2 is an integer of 0 to 6. n3 is 0. n4 is an integer of 0 to 4. W is a nitrogen atom-containing aliphatic heterocyclic ring having 2 to 20 carbon atoms which may contain a hetero atom. L + and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a hetero atom. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. When n2 ≥ 2, a plurality of R 1 may be bonded to each other to form a ring together with the carbon atom on W to which they are bonded. R 2 is a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. When n4 ≥ 2, a plurality of R 2 may be bonded to each other to form a ring together with the carbon atom on the aromatic ring to which they are bonded. R AL is an acid-labile group that undergoes a deprotection reaction with a strong acid. Z + is an onium cation represented by any one of the following formulas (cation-1) to (cation-3). [Chemical formula] (In the formula, R 11 ~R 19 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a hetero atom. Also, R11 and R 12 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. 2.R AL However, the onium salt of one group represented by the following formula (AL-1) or (AL-2). [ka] (In the formula, L c It is either -O- or -S-. R 3 , R 4 and R 5 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms. Also, R 3 , R 4 and R 5 Any two of these may be joined together to form a ring. R 6 and R 7 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 8 is a hydrocarbyl group having 1 to 20 carbon atoms, and the -CH2- of the hydrocarbyl group may be substituted with -O- or -S-. Also, R 7 and R 8 and are bonded to each other, and the carbon atoms and L that they bond to are bonded to. c Together with these, a heterocyclic group having 3 to 20 carbon atoms may be formed, and the -CH2- of the heterocyclic group may be substituted with -O- or -S-. m1 and m2 are independently either 0 or 1. * represents a bond with an adjacent -O-. 3. One onium salt in which W is represented by one of the following formulas. [ka] (In the formula, * represents L) A This represents a bond with R, where ** is R AL This represents a bond with -OC(=O). 4. One of the onium salts 1-3 represented by the following formula (1A). [ka] (In the formula, n1~n4, W, L B , R 1 , R 2 , R AL and Z + (This is the same as above.) 5. The onium salt of 4 that is represented by the following formula (1B). [ka] (In the formula, n1, n2, n4, W, L B , R 1 , R 2 , R AL and Z + (This is the same as above.) A quencher consisting of one of the onium salts from 6.1 to 6.5. A resist composition containing a 7.6 quencher. 8. Furthermore, 7 resist compositions containing an organic solvent. 9. A resist composition of 7 or 8 comprising a base polymer containing repeating units represented by the following formula (a1). [ka] (In the formula, R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 -The phenylene group or naphthylene group may be substituted with a carbon-1 to carbon-10 alkoxy group or halogen atom, which may contain a fluorine atom. 11 This is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. The saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain. AL 1 It is an acid-unstable group. 10. 9 resist compositions wherein the base polymer further comprises repeating units represented by the following formula (a2). [ka] (In the formula, R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 2 The bond is either a single bond or an *-C(=O)-O- bond. The asterisk (*) represents a bond with a carbon atom in the main chain. R 21 This refers to a C1-C20 hydrocarbyl group which may contain a halogen atom, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. AL 2 It is an acid-unstable group. 'a' is an integer between 0 and 4. 11. 9 or 10 resist compositions wherein the base polymer further comprises repeating units represented by the following formula (b1) or (b2). [ka] (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 The bond is either a single bond or an *-C(=O)-O- bond. The asterisk (*) represents a bond with a carbon atom in the main chain. R 22 This refers to a group having 1 to 20 carbon atoms that includes at least one structure selected from a hydrogen atom, or a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-OC(=O)-). R 23This refers to a C1-C20 hydrocarbyl group which may contain a halogen atom, a hydroxyl group, a nitro group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. b is an integer between 1 and 4. c is an integer between 0 and 4. However, 1 ≤ b + c ≤ 5. 12. A resist composition according to any of 9 to 11, wherein the base polymer further comprises repeating units represented by any of the following formulas (c1) to (c4). [ka] (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 This is either a single bond or a phenylene group. Z 2 is *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or *-OZ 21 - is Z 21 This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z 3 These are, independently, a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ. 31 - is Z 31 This is an aliphatic hydrocarbylene group, a phenylene group, or a naphthylene group having 1 to 10 carbon atoms, and the aliphatic hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. Z 4 These are, independently, single bonds, *-Z 41 -C(=O)-O-, *-C(=O)-NH-Z41 -or *-OZ 41 - is. is. Z 41 This is a hydroxylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Z 5 These are, independently, single bonds, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 -or *-OZ 51 - is Z 51 This is a hydroxylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Z 6 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-OZ. 61 -, *-C(=O)-N(H)-Z 61 -or *-OZ 61 - is Z 61 This is a phenylene group substituted with an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond with a carbon atom in the main chain. R 31 and R 32 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Also, R 31 and R 32 These may bond with each other to form a ring with the sulfur atom to which they are bonded. L 1 These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Rf 1 and Rf 2 Each of these is independently either a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. However, all of the Rf 5 and Rf 6 do not simultaneously become hydrogen atoms. M - is a non-nucleophilic counter ion. A + is an onium cation. d is an integer from 0 to 3.) 13. Further, a resist composition according to any one of 7 to 12, further comprising a photoacid generator. 14. Further, a resist composition according to any one of 7 to 13, further comprising a quencher other than the quencher of 6. 15. Further, a resist composition according to any one of 7 to 14, further comprising a surfactant. 16. A pattern forming method comprising a step of forming a resist film on a substrate using a resist material according to any one of 7 to 15, a step of exposing the resist film with high energy rays, and a step of developing the exposed resist film using a developer. 17. The pattern forming method according to 16, wherein the high energy rays are KrF excimer laser light, ArF excimer laser light, EB or EUV having a wavelength of 3 to 15 nm.

Effect of the Invention

[0014] The onium salt of the present invention functions well as a quencher in a resist composition. A resist film obtained from a resist composition containing the onium salt of the present invention has good sensitivity, excellent dissolution contrast, and as a result, CDU of a hole pattern and LWR of a line pattern are improved, and a high-resolution pattern profile excellent in rectangularity can be constructed.

Mode for Carrying Out the Invention

[0015] [Onium Salt] The onium salt of the present invention is represented by the following formula (1).

Chemical formula

[0016] In formula (1), n1 is an integer of 0 or 1. When n1 = 0, it represents a benzene ring, and when n1 = 1, it represents a naphthalene ring. From the perspective of solvent solubility, a benzene ring with n1 = 0 is preferred. n2 is an integer from 0 to 6. n3 is an integer from 0 to 3, preferably from 0 to 2, and more preferably 0 or 1. When n3 is other than 0, the aromatic hydroxy group bonded to the aromatic ring acts as an acid diffusion control group, and when it is adjacent to the carboxylate group on the aromatic ring, the solvent solubility is improved by hydrogen bonding. n4 is an integer from 0 to 4.

[0017] In formula (1), W is a nitrogen atom-containing aliphatic heterocyclic ring having 2 to 20 carbon atoms which may contain heteroatoms. Specific examples of the structure of W include, but are not limited to, those shown below. In the following formulas, * represents a bond to L A and ** represents a bond to R AL -O-C(=O)-.

Chemical formula

[0018] In formula (1), L A and L B are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. Among these, a single bond, an ether bond, an ester bond or an amide bond is preferred, and a single bond, an ester bond or an amide bond is more preferred.

[0019] In formula (1), X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain heteroatoms. The hydrocarbylene group may be linear, branched or cyclic, and specific examples thereof include an alkanediyl group, a cyclic saturated hydrocarbylene group and the like. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom and the like.

[0020] X L Specific examples of C1-C40 hydrocarbylene groups that may contain heteroatoms represented by the formulas shown below are, but are not limited to, those listed below. In the formulas below, * represents L A and L B This represents a combination of two things. [ka]

[0021] [ka]

[0022] [ka]

[0023] Of these, X L -0~X L -22 and X L -47~X L -49 is preferred, X L -0~X L -17 is more preferable.

[0024] In formula (1), R 1 This is a C1-C20 hydrocarbyl group which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as decyl groups, adamantyl groups, and adamantylmethyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl groups, naphthyl groups, and anthryl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, the group may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, amide bonds, imide bonds, lactone rings, sultone rings, thiolactone rings, lactam rings, sultam rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0025] Also, when n2 ≥ 2, multiple R 1 However, they may bond to each other and form a ring together with the carbon atom on W to which they are bonded. Specific examples of the ring formed in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc. Furthermore, some or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the inclusion of a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano 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)-OC(=O)-), a haloalkyl group, etc. Also, two R bonded to the same atom forming W 1 However, they may bond with each other to form a ring, creating a spiro ring.

[0026] In formula (1), R 2R is a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. Specific examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R 1 Examples of hydrocarbyl groups represented by the same as those exemplified are also available. Furthermore, when n4≧2, multiple R 2 However, they may bond with each other and form a ring structure together with the carbon atoms on the aromatic ring to which they are bonded. A specific example of the ring formed in this case is a group of R 1 Examples of rings that can be formed when these elements bond to each other and together with the carbon atoms on the W to which they bond are similar to those exemplified.

[0027] In formula (1), R AL R is an acid-unstable group that undergoes a deprotection reaction with strong acids. Specifically, R AL It is preferable that the group is represented by the following formula (AL-1) or (AL-2). [ka] (In the formula, * represents a bond with an adjacent oxygen atom.)

[0028] In formula (AL-1), R 3 , R 4 and R 5 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms. Also, R 3 , R 4 and R 5 Any two of these may be joined together to form a ring. m1 is either 0 or 1.

[0029] In formula (AL-2), L c It is -O- or -S-. 6 and R 7 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 8is a hydrocarbyl group having 1 to 20 carbon atoms, and the -CH2- of the hydrocarbyl group may be substituted with -O- or -S-. Also, R 7 and R 8 and are bonded to each other, and the carbon atoms and L that they bond to are bonded to. c Together with these, a heterocyclic group having 3 to 20 carbon atoms may be formed, and the -CH2- of the heterocyclic group may be substituted with -O- or -S-. m2 is 0 or 1.

[0030] Specific examples of acid-unstable groups represented by formula (AL-1) are listed below, but are not limited to these. In the following formulas, * represents a bond with an adjacent -O-. [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] Specific examples of acid-unstable groups represented by formula (AL-2) are listed below, but are not limited to these. In the following formulas, * represents a bond with an adjacent -O-. [ka]

[0042] [ka]

[0043] The onium salt represented by formula (1) is preferably the one represented by formula (1A) below. [ka] (In the formula, n1~n4, W, L B , R 1 , R 2 , R AL and Z + (This is the same as above.)

[0044] The onium salt represented by formula (1A) is preferably the one represented by formula (1B) below. [ka] (In the formula, n1, n2, n4, W, L B , R 1 , R 2 , R AL and Z + (This is the same as above.)

[0045] Specific examples of anions of onium salts represented by formula (1) are listed below, but are not limited to these. [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054]

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[0055]

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[0056]

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[0059]

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[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] In formula (1), Z + This is an onium cation. The onium cation is preferably one represented by any of the following formulas (cation-1) to (cation-3). [ka]

[0106] In formulas (cation-1)~(cation-3), R 11 ~R 19 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; C3-C30 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C30 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C30 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C6-C30 aryl groups such as phenyl, naphthyl, and thienyl groups; C7-C30 aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. 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 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)-OC(=O)-), a haloalkyl group, etc.

[0107] Also, R 11 and R 12 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, specific examples of sulfonium cations represented by formula (cation-1) include those represented by the following formula. [ka] (In the formula, the dashed line represents R 13 (This is a combination of the two.) Specific examples of cations of sulfonium salts represented by formula (cation-1) are listed below, but are not limited to these.

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] [ka]

[0117]

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[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] Specific examples of iodonium cations represented by formula (cation-2) are listed below, but are not limited to these. [ka]

[0135] [ka]

[0136] Specific examples of ammonium cations represented by formula (cation-3) are listed below, but are not limited to these. [ka]

[0137] Specific structures of the onium salt of the present invention include any combination of the anion and cation described above.

[0138] The onium salt of the present invention can be synthesized by known methods. As an example, a method for producing the onium salt represented by the following formula (NSQ-1-ex) will be described. [ka] (In the formula, n1~n4, W, L A , X L , R 1 , R 2 , R AL and Z + The same applies as described above. X M is a group that forms a primary or secondary ester with adjacent -CO2- groups. + X is a countercation. - (This is an anti-anion.)

[0139] The first step involves the reaction of raw material SM-1, which can be synthesized commercially or by known synthesis methods, with raw material SM-2 to obtain the intermediate In-1-ex. Various condensing agents can be used when directly forming an ester bond between the carboxyl group of raw material SM-1 and the hydroxyl group of raw material SM-2. Examples of condensing agents that can be used include N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. However, from the viewpoint of ease of removal of urea compounds produced as by-products after the reaction, it is preferable to use 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The reaction is carried out by dissolving raw materials SM-1 and SM-2 in a halogenated solvent such as methylene chloride and adding the condensing agent. Adding 4-dimethylaminopyridine as a catalyst can improve the reaction rate. The reaction time is typically around 12-24 hours, although it is desirable to monitor the reaction using silica gel thin-layer chromatography (TLC) to complete the reaction for optimal yield. After stopping the reaction, the intermediate In-1-ex can be obtained by removing any by-product urea compounds by filtration or washing with water, and then performing a standard aqueous work-up of the reaction mixture. The obtained intermediate In-1-ex can be purified by conventional methods such as distillation, chromatography, or recrystallization, if necessary.

[0140] The second step involves obtaining intermediate In-2-ex by alkaline hydrolysis of intermediate In-1-ex. Specifically, this step involves alkaline hydrolysis of the carboxylic acid ester in intermediate In-1-ex using an alkali metal hydroxide salt or an organic cation hydroxide salt to obtain intermediate In-2-ex, which is a carboxylic acid salt. Examples of alkali metal hydroxide salts that can be used include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of organic cation hydroxide salts include tetramethylammonium hydroxide and benzyltrimethylammonium hydroxide. The reaction is carried out by dissolving intermediate In-1-ex in an ether-based solvent such as tetrahydrofuran or 1,4-dioxane, and adding aqueous solutions of the various hydroxide salts. The reaction time is usually around 12 to 24 hours, although it is desirable to monitor the reaction using silica gel thin-layer chromatography (TLC) to complete the reaction for better yield. Intermediate In-2-ex can be obtained by performing a normal aqueous work-up from the reaction mixture. The resulting intermediate, In-2-ex, can be purified by conventional methods such as chromatography and recrystallization, if necessary.

[0141] The third step is to use the obtained intermediate In-2-ex in Z + X - This is a process to obtain an onium salt (NSQ-1-ex) by exchanging it with the onium salt represented by X. - Chloride ions, bromide ions, iodide ions, or methyl sulfate anions are preferred as they facilitate quantitative exchange reactions. Confirmation of the reaction progress by silica gel thin-layer chromatography (TLC) is desirable for yield. The onium salt NSQ-1-ex can be obtained from the reaction mixture by conventional aqueous work-up. If necessary, it can be purified by conventional methods such as chromatography and recrystallization.

[0142] In the above scheme, the ion exchange in the third step can be easily carried out by known methods, for example, by referring to Japanese Patent Application Publication No. 2007-145797.

[0143] The above manufacturing method is merely an example, and the method for producing onium salt according to the present invention is not limited thereto.

[0144] [Quencher] The onium salt of the present invention is useful as a quencher. In this invention, a quencher is a material that traps the acid generated from the photoacid generator in the resist composition, thereby preventing its diffusion to unexposed areas and forming a desired pattern.

[0145] When the onium salt of the present invention is brought into coexistence with an onium salt that generates a strong acid, such as a sulfonic acid, imido acid, or methidic acid with a fluorinated α-position, the corresponding carboxylic acid and the strong acid are generated upon light irradiation. On the other hand, many undecomposed onium salts remain in areas with less exposure. The strong acid acts as a catalyst for the deprotection reaction of acid-unstable groups of the base polymer, but the onium salt of the present invention hardly causes any deprotection reaction. The strong acid undergoes ion exchange with the remaining sulfonium carboxylic acid salt, becoming an onium salt of the strong acid, and in its place, the carboxylic acid is released. In other words, the strong acid is neutralized by the onionium carboxylic acid salt through ion exchange. That is, the onium salt of the present invention functions as a quencher. Such onium salt type quenchers generally tend to have a lower LWR of the resist pattern than quenchers using amine compounds.

[0146] The exchange of salt between the strong acid and the onium carboxylate is repeated countless times. The location where the strong acid is generated at the end of exposure is different from the location where the initial strong acid-generating onium salt is present. It is presumed that the repeated cycle of acid generation and salt exchange due to light averages out the acid generation points, thereby reducing the LWR of the resist pattern after development.

[0147] Materials exhibiting a similar quenching effect through a similar mechanism include, for example, onium carboxylates, onium alkanesulfonic acids, onium arene sulfonic acids, and onium α,α-difluorocarboxylates, as described in Patent Documents 1 to 6. Types of onium salts include sulfonium salts, iodonium salts, and ammonium salts. When onium alkanesulfonic acids or onium arene sulfonic acids are used, the acid strength of the generated acid is relatively high, so some of it acts as an acid generator rather than a quencher, causing a deprotection reaction, which reduces resolution performance, increases acid diffusion, and degrades resist performance such as exposure margin (EL) and mask error factor (MEF). Furthermore, in the case of onium α,α-difluorocarboxylate described in Patent Document 6, although it is an onium carboxylate salt, it has a fluorine atom at the α-position of the carboxylate anion, so the acidity of the generated acid is relatively high, similar to the onium sulfonic acid salts, and depending on the selection of acid-unstable groups in the base polymer, it may cause a deprotection reaction. Similarly, onium fluorocarboxylic acid salts, which are simply linearized onium salts, exhibit significant acid diffusion, leading to salt exchange with strong acids in unexposed areas, resulting in reduced resolution, EL, and MEF. Alkanecarboxylic acids, while functioning as quenchers, are highly hydrophilic. Onium fluoroalkanecarboxylic acid salts, as described in Patent Document 3, allow for some control of hydrophilicity compared to non-fluorine types, but control is still insufficient when the number of carbon atoms is small. Examples of onium perfluoroalkanecarboxylic acid salts with a large number of carbon atoms exist, but in these cases, the carboxylic acid exhibits surfactant-like properties, resulting in poor compatibility with the resist composition. Poor compatibility with the resist composition can lead to defect formation. Furthermore, perfluoroalkanecarboxylic acids are undesirable from a biological and environmental perspective.

[0148] Furthermore, Patent Documents 7-9 describe nitrogen-containing heterocyclic compounds such as indole and indoline, and onium carboxylate salts having a piperidinecarboxylic acid structure, Patent Document 10 describes an onium carboxylate salt having an aminobenzoic acid structure, and Patent Document 11 describes an onium carboxylate salt having an amide bond. Although these also act as quenchers, aromatic amines and amide bonds are not highly basic, so their acid diffusion control ability is insufficient, and piperidinecarboxylic acid is extremely water-soluble, which promotes the penetration of alkaline developer into unexposed areas, raising concerns about the collapse of the resist pattern and peeling from the substrate.

[0149] The onium salt of the present invention can solve the aforementioned problems. The onium salt, which has a nitrogen atom-containing aliphatic heterocycle and an aromatic carboxylic acid structure in its anion, acts as a quencher, effectively trapping the strong acid generated from the acid generator in the exposed area at the aromatic carboxylic acid anion moiety. At the same time, the acid-unstable group protecting the nitrogen atom-containing aliphatic heterocycle moiety undergoes a deprotection reaction with the strong acid, generating a highly basic nitrogen atom-containing aliphatic heterocyclic compound. The highly basic nitrogen atom-containing aliphatic heterocycle moiety suppresses excessive diffusion of acid into the unexposed area, and the carboxylic acid anion moiety continuously repeats proton exchange with the strong acid. It is believed that these synergistic effects improve the dissolution contrast between the exposed and unexposed areas and appropriately control the acid diffusion of the strong acid, thereby achieving good lithography performance even in the formation of fine patterns. Furthermore, the combination of an aromatic carboxylic acid structure and an acid-unstable group protecting the nitrogen atom-containing aliphatic heterocyclic moiety provides an appropriate number of carbon atoms, improving solubility in organic solvents. This effectively suppresses the penetration of alkaline developer into unexposed areas and the resulting deformation and peeling of the resist pattern.

[0150] [Resist composition] The resist composition of the present invention, (A) Contains a quencher consisting of an onium salt represented by formula (1) as an essential component.

[0151] In the resist composition of the present invention, the content of (A) quencher is preferably 0.1 to 40 parts by mass, and more preferably 1 to 20 parts by mass, relative to 80 parts by mass of (C) base polymer, as described later. When the content of (A) quencher is within the above range, it functions sufficiently as a quencher and there is no risk of performance degradation such as decreased sensitivity or generation of foreign matter due to insufficient solubility.

[0152] [(B) Organic solvents] The resist composition of the present invention may contain an organic solvent as component (B). The organic solvent (B) is not particularly limited as long as it can dissolve component (A) and each of the components described later. Specific examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; keto alcohols such as diacetone alcohol (DAA); propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, and propylene glycol Examples include ethers such as dimethyl ether and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate (PGMEA), 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; lactones such as γ-butyrolactone (GBL); and mixed solvents thereof.

[0153] Among these organic solvents, PGME, PGMEA, cyclohexanone, GBL, DAA, ethyl lactate, and mixed solvents thereof are preferred, as they exhibit particularly excellent solubility of the base polymer of component (C).

[0154] In the resist composition of the present invention, the content of (B) organic solvent is preferably 200 to 5,000 parts by mass, and more preferably 400 to 3,500 parts by mass, relative to 80 parts by mass of (C) base polymer, as described later. (B) organic solvent may be used alone or as a mixture of two or more types.

[0155] [(C) Base polymer] The resist composition of the present invention may include a base polymer as component (C). The (C) base polymer contains a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1). [ka]

[0156] In formula (a1), R A X is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 -The phenylene group or naphthylene group may be substituted with a carbon-1 to carbon-10 alkoxy group or halogen atom, which may contain a fluorine atom. 11 This is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. The saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * represents a bond with a carbon atom of the main chain.

[0157] In formula (a1), AL 1 This is an acid-unstable group. Examples of such acid-unstable groups include those described in Japanese Patent Publication No. 2013-80033 and Japanese Patent Publication No. 2013-83821.

[0158] Typically, the acid-unstable groups mentioned above are those represented by the following formulas (AL-3) to (AL-5). [ka] (In the equation, dashed lines represent connections.)

[0159] In equations (AL-3) and (AL-4), R L1 and R L2 Each of these is independently a saturated hydrocarbyl group having 1 to 40 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. The saturated hydrocarbyl group is preferably one having 1 to 20 carbon atoms.

[0160] In formula (AL-3), k is an integer between 0 and 10, preferably between 1 and 5.

[0161] In formula (AL-4), R L3 and R L4 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, or fluorine atoms. The hydrocarbyl group may be linear, branched, or cyclic. Also, R L2 , R L3 and R L4 Any two of these may bond with each other to form a ring having 3 to 20 carbon atoms, together with the carbon atom to which they are bonded, or a carbon atom and an oxygen atom. The ring is preferably a ring having 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0162] In formula (AL-5), R L5 , R L6 and R L7 Each of these is independently a saturated 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 linear, branched, or cyclic. Also, R L5 , R L6 and R L7 Any two of these may bond with each other to form a ring with 3 to 20 carbon atoms. The ring is preferably a ring with 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0163] Specific examples of repeating unit a1 are shown below, but are not limited to these. Note that in the following formula, R A and AL 1 This is the same as described above. [ka]

[0164] [ka]

[0165] [ka]

[0166] The base polymer may further contain repeating units represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0167] In formula (a2), R A X is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 The bond is either a single bond or *-C(=O)-O-. * represents a bond with a carbon atom in the main chain. 21 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. a is an integer from 0 to 4, preferably 0 or 1. AL 2 This is an acid-unstable group. The acid-unstable group is AL. 1Examples of acid-unstable groups represented by the symbol shown are similar to those exemplified above.

[0168] Specific examples of repeating unit a2 are shown below, but are not limited to these. Note that in the following formula, R A and AL 2 This is the same as described above. [ka]

[0169] Preferably, the base polymer further contains a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0170] In equations (b1) and (b2), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 The bond is either a single bond or *-C(=O)-O-. * represents a bond with a carbon atom in the main chain. 22 R is a group having 1 to 20 carbon atoms that includes at least one structure selected from a hydrogen atom, or a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-OC(=O)-). 23b is a C1-C20 hydrocarbyl group which may contain a halogen atom, a hydroxyl group, a nitro group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. b is an integer from 1 to 4. c is an integer from 0 to 4, where 1 ≤ b + c ≤ 5.

[0171] Specific examples of repeating unit b1 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179] [ka]

[0180] [ka]

[0181] [ka]

[0182] [ka]

[0183] [ka]

[0184] [ka]

[0185] [ka]

[0186] [ka]

[0187] Specific examples of repeating unit b2 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0188] [ka]

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] As for the repeating unit b1 or b2, in ArF lithography, it is particularly preferable to have a lactone ring as a polar group, and in KrF lithography, EB lithography, and EUV lithography, it is preferable to have a phenol moiety.

[0193] The base polymer may further contain repeating units represented by any of the following formulas (c1) to (c4) (hereinafter also referred to as repeating units c1 to c4). [ka]

[0194] In formulas (c1) to (c4), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 This is a single bond or a phenylene group. 2 is *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or *-OZ 21 - is Z 21This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 These are, independently, a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ. 31 - is Z 31 This is an aliphatic hydrocarbylene group, a phenylene group, or a naphthylene group having 1 to 10 carbon atoms, and the aliphatic hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. 4 These are, independently, single bonds, *-Z 41 -C(=O)-O-, *-C(=O)-NH-Z 41 -or *-OZ 41 - is. is. Z 41 This is a hydrocarbylene group having 1 to 20 carbon atoms, which may contain heteroatoms. 5 These are, independently, single bonds, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 -or *-OZ 51 - is Z 51 This is a hydrocarbylene group having 1 to 20 carbon atoms, which may contain heteroatoms. 6 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-OZ. 61 -, *-C(=O)-N(H)-Z 61 -or *-OZ 61 - is Z 61 This is a phenylene group substituted with an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond with a carbon atom in the main chain.

[0195] Z 21 , Z 31 and Z 61The aliphatic hydrocarbylene group represented by can be linear, branched, or cyclic, and specific examples include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane- Examples include alkanediyl groups such as 2,3-diyl group, butane-1,4-diyl group, 1,1-dimethylethane-1,2-diyl group, pentane-1,5-diyl group, 2-methylbutane-1,2-diyl group, and hexane-1,6-diyl group; cycloalkanediyl groups such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; and groups obtained by combining these.

[0196] Z 41 and Z 51 The hydrocarbylene group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples are listed below, but are not limited to these. [ka] (In the equation, dashed lines represent connections.)

[0197] In formula (c1), R 31 and R 32Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; C3-C20 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; C2-C20 alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; C3-C20 cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; C6-C20 aryl groups such as phenyl, naphthyl, and thienyl groups; aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. 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 have a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom interposed therein, 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 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)-OC(=O)-), a haloalkyl group, etc.

[0198] Also, R 31 and R 32 These may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, the ring is defined as R in the explanation of formula (cation-1). 11 and R 12 Examples of rings that can be formed when these atoms bond together with the sulfur atom to which they bond are similar to those exemplified.

[0199] Specific examples of cations of repeating unit c1 are listed below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0200] [ka]

[0201] [ka]

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] [ka]

[0206] In formula (c1), M -These are non-nucleophilic counterions. Specific examples of the aforementioned 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.

[0207] Furthermore, specific examples of the non-nucleophilic counterions include a sulfonate anion represented by the following formula (c1-1) in which the α position is substituted with a fluorine atom, and a sulfonate anion represented by the following formula (c1-2) in which the α position is substituted with a fluorine atom and the β position is substituted with a trifluoromethyl group. [ka]

[0208] In formula (c1-1), R 33 This is a hydrogen atom, a C1-C30 hydrocarbyl group, a C2-C30 hydrocarbylcarbonyloxy group, or a C2-C30 hydrocarbyloxycarbonyl group, and the hydrocarbyl group may contain a halogen atom, an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl portion of the hydrocarbyl group, the hydrocarbylcarbonyloxy group, and the hydrocarbyl oxycarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (2A') described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0209] In formula (c1-2), R 34 This is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 2 to 30 carbon atoms, and the hydrocarbyl group and hydrocarbylcarbonyl group may contain a halogen atom, an ether bond, an ester bond, a carbonyl group, or a lactone ring. 35 R is a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. The hydrocarbyl portion of the hydrocarbyl group and hydrocarbylcarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (2A') described later. fa1 Examples of hydrocarbyl groups represented by R are similar to those exemplified. 35 A trifluoromethyl group is preferred as the component.

[0210] Specific examples of sulfonate anions represented by formula (c1-1) or (c1-2) are listed below, but are not limited to these. Note that in the following formulas, R 35 This is the same as above, and Ac is an acetyl group. [ka]

[0211] [ka]

[0212] [ka]

[0213] [ka]

[0214] [ka]

[0215] [ka]

[0216] [ka]

[0217] [ka]

[0218] [ka]

[0219] [ka]

[0220] In formulas (C2) and (C3), L 1 These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Of these, ether bonds, ester bonds, and carbonyl groups are preferred from a synthetic viewpoint, and ester bonds and carbonyl groups are more preferred.

[0221] In formula (C2), Rf 1 and Rf 2 Each of these is independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Of these, Rf 1 and Rf 2 To increase the acid strength of the generated acid, it is preferable that all atoms be fluorine atoms. Rf 3 and Rf 4 These are, independently, a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Of these, Rf is used to improve solvent solubility. 3 and Rf 4At least one of them is preferably a trifluoromethyl group.

[0222] In formula (C3), Rf 5 and Rf 6 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. However, all Rf 5 and Rf 6 These cannot simultaneously become hydrogen atoms. Of these, Rf 5 and Rf 6 At least one of them is preferably a trifluoromethyl group.

[0223] In formulas (C2) and (C3), d is an integer between 0 and 3, but 1 is preferred.

[0224] Specific examples of anions with repeating unit c2 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0225] [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] Specific examples of anions with repeating unit c3 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0232] [ka]

[0233] [ka]

[0234] [ka]

[0235] [ka]

[0236] [ka]

[0237] [ka]

[0238] Specific examples of anions with repeating unit c4 are shown below, but are not limited to these. Note that in the following formula, R A This is the same as described above. [ka]

[0239] In formulas (C2) to (C4), A + This is an onium cation. Examples of the onium cation include sulfonium cations, iodonium cations, and ammonium cations, but sulfonium cations and iodonium cations are preferred. Specific structures of these include those similar to those exemplified as cations represented by formulas (cation-1) to (cation-3).

[0240] The repeating units c1 to c4 function as photoacid generators. When a base polymer containing repeating units c1 to c4 (i.e., a polymer-bound type acid generator) is used, the resist composition of the present invention may or may not contain the (D) photoacid generator described later.

[0241] The base polymer may further contain repeating units (hereinafter also referred to as repeating unit d) having a structure in which a hydroxyl group is protected by an acid-unstable group. The repeating unit d is not particularly limited as long as it has one or more structures in which a hydroxyl group is protected and the protecting group decomposes upon the action of an acid to generate a hydroxyl group, but it is preferably represented by the following formula (d1). [ka]

[0242] In formula (d1), R A The same as above. R 41 R is a (e+1) valent hydrocarbon group having 1 to 30 carbon atoms, which may contain heteroatoms. 42 is an acid-unstable group. e is an integer between 1 and 4.

[0243] In formula (d1), R 42 The acid-unstable group represented by can be any group that is deprotected by the action of an acid and generates a hydroxyl group. 42The structure is not particularly limited, but acetal structures, ketal structures, alkoxycarbonyl groups, and alkoxymethyl groups represented by the following formula (d2) are preferred, and alkoxymethyl groups represented by the following formula (d2) are particularly preferred. [ka] (In the formula, * represents a bond. R 43 (This refers to a hydrocarbyl group with 1 to 15 carbon atoms.)

[0244] R 42 Specific examples of the acid-unstable group represented by formula (d2), the alkoxymethyl group represented by formula (d2), and the repeating unit d are the same as those exemplified in the description of the repeating unit d described in Japanese Patent Application Publication No. 2020-111564.

[0245] The base polymer may further contain repeating units e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Specific examples of monomers that give repeating units e are listed below, but are not limited to these. [ka]

[0246] The base polymer may further contain repeating units f derived from indan, vinylpyridine, or vinylcarbazole.

[0247] In the polymer of the present invention, the content ratios of the repeating units a1, a2, b1, b2, c1 to c4, d, e and f are preferably 0 < a1 ≦ 0.8, 0 ≦ a2 ≦ 0.8, 0 < а1 + a2 ≦ 0.8, 0 ≦ b1 ≦ 0.6, 0 ≦ b2 ≦ 0.6, 0 ≦ b1 + b2 ≦ 0.6, 0 ≦ c1 ≦ 0.4, 0 ≦ c2 ≦ 0.4, 0 ≦ c3 ≦ 0.4, 0 ≦ c4 ≦ 0.4, 0 ≦ c1 + c2 + c3 + c4 ≦ 0.4, 0 ≦ d ≦ 0.5, 0 ≦ e ≦ 0.3 and 0 ≦ f ≦ 0.3, more preferably 0 < a1 ≦ 0.7, 0 ≦ a2 ≦ 0.7, 0 < а1 + a2 ≦ 0.7, 0 ≦ b1 ≦ 0.5, 0 ≦ b2 ≦ 0.5, 0 ≦ b1 + b2 ≦ 0.5, 0 ≦ c1 ≦ 0.3, 0 ≦ c2 ≦ 0.3, 0 ≦ c3 ≦ 0.3, 0 ≦ c4 ≦ 0.3, 0 ≦ c1 + c2 + c3 + c4 ≦ 0.3, 0 ≦ d ≦ 0.3, 0 ≦ e ≦ 0.3 and 0 ≦ f ≦ 0.3. However, a1 + a2 + b1 + b2 + c1 + c2 + c3 + c4 + d + e + f = 1.0.

[0248] The weight average molecular weight (Mw) of the polymer is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of deterioration of resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene equivalent measurement value by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0249] Furthermore, since the influence of the molecular weight distribution (Mw / Mn) of the polymer becomes larger as the pattern rule is miniaturized, in order to obtain a resist composition suitably used for fine pattern dimensions, Mw / Mn is preferably narrow-dispersed at 1.0 to 2.0. If it is within the above range, there is little polymer with low molecular weight or high molecular weight, and there is no risk that foreign matter is seen on the pattern or the shape of the pattern deteriorates after exposure.

[0250] To synthesize the polymer, for example, a monomer that gives the above-described repeating unit may be heated in an organic solvent with a radical polymerization initiator added thereto to carry out polymerization.

[0251] Examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), PGMEA, and GBL. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% of the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, and more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0252] The polymerization initiator may be added to the monomer solution and supplied to the reaction vessel, or an initiator solution may be prepared separately from the monomer solution and each supplied to the reaction vessel independently. Since the polymerization reaction may proceed and a superpolymer may be formed by radicals generated from the initiator during the waiting time, it is preferable from a quality control viewpoint to prepare the monomer solution and the initiator solution independently and add them dropwise. The acid-unstable group may be used as is, introduced into the monomer, or it may be protected or partially protected after polymerization. In addition, known chain transfer agents such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination to adjust the molecular weight. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% of the total amount of monomers to be polymerized.

[0253] In the case of 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 alkaline hydrolysis may be performed after polymerization.

[0254] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene may be polymerized by heating in an organic solvent with a radical polymerization initiator. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to obtain polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0255] Ammonia water, triethylamine, etc., can be used as the base during alkaline hydrolysis. 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.

[0256] The amount of each monomer in the monomer solution can be appropriately set, for example, to achieve a preferred content ratio of the repeating units described above.

[0257] The polymer obtained by the above manufacturing method may be treated as a final product if it is a reaction solution obtained by a polymerization reaction, or as a final product if it is a powder obtained by a purification process such as a reprecipitation method in which the polymerization solution is added to a poor solvent and a powder is obtained. However, from the viewpoint of work efficiency and quality stabilization, it is preferable to treat the polymer solution obtained by dissolving the powder obtained by the purification process in a solvent as the final product.

[0258] Specific examples of solvents used in this process include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; and PGME, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether. Examples include ethers; esters such as PGMEA, 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; lactones such as GBL; alcohols such as DAA; high-boiling point alcoholic solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0259] In the polymer solution, the concentration of the polymer is preferably 0.01 to 30% by mass, and more preferably 0.1 to 20% by mass.

[0260] It is preferable to filter the reaction solution or polymer solution. Filtering removes foreign matter and gel that may cause defects, which is effective in stabilizing quality.

[0261] Examples of filter materials used in the aforementioned filter filtration include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon materials. However, in the filtration process of the resist composition, filters made of fluorocarbon materials such as Teflon (registered trademark), hydrocarbon materials such as polyethylene and polypropylene, or nylon are preferred. The pore size of the filter can be appropriately selected according to the desired level of cleanliness, but is preferably 100 nm or less, and more preferably 20 nm or less. These filters may be used individually or in combination. The filtration method may involve passing the solution through only once, but it is more preferable to circulate the solution and filter it multiple times. The filtration process can be carried out in any order and number of times in the polymer manufacturing process, but it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0262] (C) The base polymer may be used alone, or two or more types with different composition ratios, Mw and / or Mw / Mn may be used in combination. In addition, (C) the base polymer may also contain hydrogenated ring-opening metathesis polymers, for which those described in Japanese Patent Publication No. 2003-66612 may be used.

[0263] [(D) Photoacid Generator] The resist composition of the present invention may contain a photoacid generator as component (D). The photoacid generator of component (D) is not particularly limited as long as it is a compound that generates a strong acid upon irradiation with high-energy rays. Specific examples of suitable photoacid generators include those represented by the following formulas (2-1) or (2-2). [ka]

[0264] In equations (2-1) and (2-2), R 101 ~R 105 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain heteroatoms. Also, R101 , R 102 and R 103 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0265] Specific examples of the sulfonium cation represented by formula (2-1) include, but are not limited to, those exemplified as the sulfonium cation represented by formula (cation-1) above. Similarly, specific examples of the iodonium cation represented by formula (2-2) include, but are not limited to, those exemplified as the iodonium cation represented by formula (cation-2) above.

[0266] In equations (2-1) and (2-2), Xa - This is an anion selected from the following equations (2A) to (2D). [ka]

[0267] In formula (2A), R fa R is a C1-C40 hydrocarbyl group which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (2A') described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0268] The anion represented by formula (2A) is preferably the one represented by formula (2A') below. TIFF2026062943000193.tif1579

[0269] In formula (2A'), R HF This is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group.

[0270] R fa1This is a hydrocarbyl group having 1 to 38 carbon atoms, which may contain heteroatoms. The heteroatoms are preferably oxygen atoms, nitrogen atoms, sulfur atoms, halogen atoms, etc., with oxygen atoms being more preferred. The hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms, from the viewpoint of obtaining high resolution in fine pattern formation.

[0271] R fa1 The C1-C38 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C38 alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, pentadecyl, heptadecyl, and eicosyl; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, and 1-adamantylmethyl groups. Examples include cyclic saturated hydrocarbyl groups with 3 to 38 carbon atoms, such as norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, and dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups with 2 to 38 carbon atoms, such as allyl group and 3-cyclohexenyl group; aryl groups with 6 to 38 carbon atoms, such as phenyl group, 1-naphthyl group, and 2-naphthyl group; aralkyl groups with 7 to 38 carbon atoms, such as benzyl group and diphenylmethyl group; and groups obtained by combining these.

[0272] 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 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)-OC(=O)-), a haloalkyl group, etc. Specific examples of hydrocarbyl groups containing heteroatoms include tetrahydrofuryl group, methoxymethyl group, ethoxymethyl group, methylthiomethyl group, acetamidomethyl group, trifluoroethyl group, (2-methoxyethoxy)methyl group, acetoxymethyl group, 2-carboxy-1-cyclohexyl group, 2-oxopropyl group, 4-oxo-1-adamantyl group, 5-hydroxy-1-adamantyl group, 5-tert-butylcarbonyloxy-1-adamantyl group, and 4-oxatricyclo[4.2.1.0 3,7 Examples include nonane-5-on-2-yl groups and 3-oxocyclohexyl groups.

[0273] For details on the synthesis of sulfonium salts having the anion represented by formula (2A'), 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. Also, 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., can be suitably used.

[0274] Specific examples of anions represented by formula (2A) include those similar to those exemplified as anions represented by formulas (c1-1) and (c1-2).

[0275] In formula (2B), R fb1 and R fb2Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may each contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (2A'). fa1 Examples of hydrocarbyl groups represented by R include those similar to those exemplified. fb1 and R fb2 Preferably, R is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 These are bonded to each other, and the groups to which they bond are (-CF2-SO2-N - It may form a ring with -SO2-CF2-), in which case R fb1 and R fb2 The group obtained by the bonding of these two elements is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0276] In formula (2C), R fc1 , R fc2 and R fc3 Each of these is a hydrocarbyl group having 1 to 40 carbon atoms, which may each contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (2A'). fa1 Examples of hydrocarbyl groups represented by R include those similar to those exemplified. fc1 , R fc2 and R fc3 Preferably, R is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 These are bonded to each other, and the groups to which they bond are (-CF2-SO2-C - It may form a ring with -SO2-CF2-), in which case R fc1 and R fc2 The group obtained by the bonding of these two elements is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0277] In formula (2D), R fdR 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. A specific example is R in formula (2A'). fa1 Examples of hydrocarbyl groups represented by the same formula as those exemplified above include those shown.

[0278] The synthesis of sulfonium salts having the anion represented by formula (2D) is described in detail in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2014-133723.

[0279] Specific examples of anions represented by formula (2D) are listed below, but are not limited to these. [ka]

[0280] [ka]

[0281] Further examples of the aforementioned non-nucleophilic counterions include anions having an aromatic ring substituted with an iodine or bromine atom. A specific example of such anion is represented by the following formula (2E). [ka]

[0282] In equation (2E), x is an integer satisfying 1 ≤ x ≤ 3. y and z are integers satisfying 1 ≤ y ≤ 5, 0 ≤ z ≤ 3, and 1 ≤ y + z ≤ 5. y is preferably an integer satisfying 1 ≤ y ≤ 3, and more preferably 2 or 3. z is preferably an integer satisfying 0 ≤ z ≤ 2.

[0283] In formula (2E), X BI x is an iodine atom or a bromine atom, and when x and / or y are 2 or more, they may be the same or different from each other.

[0284] In formula (2E), L 11 This is a saturated hydrocarbylene group having 1 to 6 carbon atoms, which may contain a single bond, an ether bond, or an ester bond, or an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

[0285] In formula (2E), L 12 When x is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms, and when x is 2 or 3, it is a (x+1) valent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0286] In formula (2E), R fe This may contain a hydroxyl group, a carboxyl group, a fluorine atom, a chlorine atom, a bromine atom, or an amino group, or a fluorine atom, a chlorine atom, a bromine atom, a hydroxyl group, an amino group, or an ether bond, and may include a C1-C20 hydrocarbyl group, a C1-C20 hydrocarbyloxy group, a C2-C20 hydrocarbylcarbonyl group, a C2-C10 hydrocarbyloxycarbonyl group, a C2-C20 hydrocarbylcarbonyloxy group, or a C1-C20 hydrocarbylsulfonyloxy group, or -N(R feA )(R feB ), -N(R feC )-C(=O)-R feD Or -N(R feC )-C(=O)-OR feD That is. R feA and R feB Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may also 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. feDThis is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 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 aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When x and / or z is 2 or more, each R 8 They may be identical or different from one another.

[0287] Of these, R fe Examples include hydroxyl groups, -N(R feC )-C(=O)-R feD , -N(R feC )-C(=O)-OR feD Fluorine atoms, chlorine atoms, bromine atoms, methyl groups, methoxy groups, etc. are preferred.

[0288] In formula (2E), Rf 11 ~Rf 14 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of these is either a fluorine atom or a trifluoromethyl group. Also, Rf 11 and Rf 12 These may combine to form a carbonyl group. In particular, Rf 13 and Rf 14 It is preferable that both are fluorine atoms.

[0289] Specific examples of anions of onium salts represented by formula (2E) are listed below, but are not limited to these. Note that in the following formula, X BI This is the same as described above. [ka]

[0290]

change

[0291]

change

[0292]

change

[0293]

change

[0294]

change

[0295]

change

[0296]

change

[0297]

change

[0298]

change

[0299]

change

[0300]

change

[0301]

change

[0302]

change

[0303]

change

[0304]

change

[0305]

change

[0306]

change

[0307]

change

[0308]

change

[0309]

change

[0310]

change

[0311] [ka]

[0312] As the non-nucleophilic counterion, you can also use a fluorobenzenesulfonic acid anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, an anion having a mechanism for decomposition by acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-070692, an anion having a cyclic ether group as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935, or an anion as described in Japanese Patent Application Publication No. 2018-092159.

[0313] As the non-nucleophilic counterions, anions of bulky benzenesulfonic acid derivatives that do not contain fluorine atoms, as described in Japanese Patent Publication No. 2006-276759, Japanese Patent Publication No. 2015-117200, Japanese Patent Publication No. 2016-65016, and Japanese Patent Publication No. 2019-202974, as well as benzenesulfonic acid anions or alkylsulfonic acid anions that do not contain fluorine atoms bonded to an aromatic group containing an iodine atom, as described in Japanese Patent Publication No. 6645464.

[0314] As the non-nucleophilic counterion, other options include the bissulfonic acid anion described in Japanese Patent Publication No. 2015-206932, the sulfonamide or sulfonimide anion described in International Publication No. 2020 / 158366, which has a sulfonic acid on one end and a different sulfonamide or sulfonimide on the other, and the sulfonate anion described in Japanese Patent Publication No. 2015-024989.

[0315] Furthermore, as the photoacid generator for component (D), one represented by the following formula (3) is also preferred. [ka]

[0316] In formula (3), R 201 and R 202Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain heteroatoms. 203 This is a hydrocarbylene group having 1 to 30 carbon atoms, which may contain heteroatoms. Also, R 201 , R 202 and R 203 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0317] R 201 and R 202 The C1-C30 hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C30 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, and tricyclo[5.2.1.0 2,6Examples 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 the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen, sulfur, or nitrogen atoms, and as a result, the material may contain hydroxyl groups, cyano groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0318] R 203The hydrocarbylene group, represented by , having 1 to 30 carbon atoms, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkane diyl groups with 1 to 30 carbon atoms, such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, etc.; cyclopentanediyl Examples include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as yl groups, cyclohexanediyl groups, norbornanediyl groups, and adamantanediyl groups; and arylene groups having 6 to 30 carbon atoms, such as phenylene groups, methylphenylene groups, ethylphenylene groups, n-propylphenylene groups, isopropylphenylene groups, n-butylphenylene groups, isobutylphenylene groups, sec-butylphenylene groups, tert-butylphenylene groups, naphthylene groups, methylnaphthylene groups, ethylnaphthylene groups, n-propylnaphthylene groups, isopropylnaphthylene groups, n-butylnaphthylene groups, isobutylnaphthylene groups, sec-butylnaphthylene groups, and tert-butylnaphthylene groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbylene 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 hydrocarbylene 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 cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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)-OC(=O)-), a haloalkyl group, etc. The heteroatom is preferably an oxygen atom.

[0319] In formula (3), L AThis is a 1-20 carbon atom hydrocarbylene group which may contain single bonds, ether bonds, or heteroatoms. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R 203 Examples of hydrocarbylene groups represented by the same formula as those exemplified above include the same groups as those shown.

[0320] In formula (3), X a , X b , X c and X d Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. However, X a , X b , X c and X d At least one of these is a fluorine atom or a trifluoromethyl group.

[0321] The photoacid generator represented by formula (3) is preferably the one represented by formula (3') below. [ka]

[0322] In formula (3'), L A The same as above. X e R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 Each of these is a hydrocarbyl group having 1 to 20 carbon atoms, which may independently contain a hydrogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (2A'). fa1 Examples of hydrocarbyl groups represented by the formula shown are similar to those exemplified. p1 and p2 are each independent integers from 0 to 5, and p3 is an integer from 0 to 4.

[0323] Examples of photoacid generators represented by formula (3) include those similar to those exemplified as photoacid generators represented by formula (2) in Japanese Patent Publication No. 2017-026980.

[0324] Among the other photoacid generators mentioned above, those containing anions represented by formula (2A') or (2D) are particularly preferred because they exhibit low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (3') are particularly preferred because they exhibit extremely low acid diffusion.

[0325] If the resist composition of the present invention contains (D) a photoacid generator, its content is preferably 0.1 to 40 parts by mass, and more preferably 0.5 to 20 parts by mass, per 80 parts by mass of the (C) base polymer. When the amount of photoacid generator of component (D) is within the above range, the resolution is good and there is no risk of foreign matter problems occurring after development or peeling of the resist film, so it is preferable. The photoacid generator of component (D) may be used alone or in combination of two or more types. By the base polymer containing any of the repeating units c1 to c4 and / or by containing the (D) photoacid generator, the resist composition of the present invention can function as a chemically amplified resist composition.

[0326] [(E) Nitrogen-containing compounds] The resist composition of the present invention has component (A) as an essential component, but may also contain nitrogen-containing compounds as other quenchers. Examples of such nitrogen-containing compounds include primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103, particularly amine compounds having a hydroxyl group, ether linkage, ester linkage, lactone ring, cyano group, or sulfonic acid ester linkage. Also, examples include compounds in which a primary or secondary amine is protected with a carbamate group, such as the compound described in Japanese Patent Publication No. 3790649.

[0327] Furthermore, a sulfonium sulfonate salt having a nitrogen-containing substituent may be used as the nitrogen-containing compound. Such a compound functions as a quencher in the unexposed area and loses its quenching ability in the exposed area through neutralization with its own generated acid, functioning as a so-called photodecayable base. By using a photodecayable base, the contrast between the exposed and unexposed areas can be further enhanced. For example, Japanese Patent Publication No. 2009-109595 and Japanese Patent Publication No. 2012-46501 can be referenced as examples of photodecayable bases.

[0328] If the resist composition of the present invention contains (E) a nitrogen-containing compound, its content is preferably 0.001 to 12 parts by mass, and more preferably 0.01 to 8 parts by mass, per 80 parts by mass of the (C) base polymer. The (E) nitrogen-containing compound may be used alone or in combination of two or more types.

[0329] [(F) Surfactants] The resist composition of the present invention may further contain a surfactant (F). Preferably, the surfactant of component (F) is a surfactant that is insoluble or sparingly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or sparingly soluble in both water and an alkaline developer. Examples of such surfactants can be found in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2011-16746.

[0330] As surfactants that are insoluble or poorly soluble in water and alkaline developer, among the surfactants described in the above publication, FC-4430 (manufactured by 3M), Surflon® S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Orfin® E1004 (manufactured by Nisshin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following formula (surf-1) are preferred. [ka]

[0331] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), notwithstanding the preceding description. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of such aliphatic groups include the divalent ethylene group, 1,4-butylene group, 1,2-propylene group, 2,2-dimethyl-1,3-propylene group, and 1,5-pentylene group, while examples of trivalent or tetravalent aliphatic groups are listed below. [ka] (In the formula, the dashed lines represent bonds, which are substructures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0332] Among these, the 1,4-butylene group and the 2,2-dimethyl-1,3-propylene group are preferred.

[0333] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, and the sum of n and m is the valence of R, an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably an integer from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. Furthermore, the order of each constituent unit in formula (surf-1) is not specified, and they may be bonded in a block-like manner or randomly. For details on the production of partially fluorinated oxetane ring-opening polymer surfactants, please refer to U.S. Patent No. 5,650,483, etc.

[0334] Surfactants that are insoluble or sparingly soluble in water and soluble in alkaline developers have the function of reducing water penetration and leaching by orienting themselves on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, they are useful in suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. Furthermore, they are useful because they become solubilized during alkaline aqueous solution development after exposure or after PEB, and are less likely to become foreign substances that cause defects. Such surfactants are insoluble or sparingly soluble in water and soluble in alkaline developers, and are polymer-type surfactants, also called hydrophobic resins, and those that have high water repellency and improve water lubricity are particularly preferred.

[0335] Specific examples of such polymer-type surfactants include those containing at least one repeating unit selected from the following formulas (4A) to (4E). [ka]

[0336] In formulas (4A) to (4E), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 R is -CH2-, -CH2CH2-, -O-, or two separated -H atoms. s1 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group or a fluorinated hydrocarbyl group, or an acid-unstable group. s3 If the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. s4 R is a (u+1) valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer from 1 to 3. s5 These are, independently, hydrogen atoms, or the formula -C(=O)-OR saIt is a group represented by R sa This is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 This is a hydrocarbyl group having 1 to 15 carbon atoms or a fluorinated hydrocarbyl group, and an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds.

[0337] R s1 The hydrocarbyl group represented by is preferably a saturated hydrocarbyl group and may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, those with 1 to 6 carbon atoms are preferred.

[0338] R s2 The hydrocarbylene group represented by is preferably a saturated hydrocarbylene group and may be linear, branched, or cyclic. Specific examples include methylene, ethylene, propylene, butylene, and pentylene groups.

[0339] R s3 or R s6 The hydrocarbyl group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include saturated hydrocarbyl groups, alkenyl groups, alkynyl groups, and other aliphatic unsaturated hydrocarbyl groups, but saturated hydrocarbyl groups are preferred. The saturated hydrocarbyl group is R s1 In addition to the examples given as hydrocarbyl groups represented by , other examples include n-undecyl group, n-dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc. s3 or R s6Examples of fluorinated hydrocarbyl groups represented by the above-mentioned hydrocarbyl group include groups in which some or all of the hydrogen atoms bonded to the carbon atoms are replaced with fluorine atoms. As mentioned above, ether bonds or carbonyl groups may be interposed between these carbon-carbon bonds.

[0340] R s3 Specific examples of acid-unstable groups represented by the formulas (AL-3) to (AL-5) mentioned above include trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and alkyl groups containing oxo groups with 4 to 20 carbon atoms.

[0341] R s4 The (u+1) valent hydrocarbon group or fluorinated hydrocarbon group represented by may be linear, branched, or cyclic. Specific examples include groups obtained by further removing u hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0342] R sa The fluorinated hydrocarbyl group represented by is preferably saturated and may be linear, branched, or cyclic. Specific examples include those in which some or all of the hydrogen atoms of the hydrocarbyl group are substituted with fluorine atoms, such as trifluoromethyl group, 2,2,2-trifluoroethyl group, 3,3,3-trifluoro-1-propyl group, 3,3,3-trifluoro-2-propyl group, 2,2,3,3-tetrafluoropropyl group, 1,1,1,3,3,3-hexafluoroisopropyl group, 2,2,3,3,4,4,4-heptafluorobutyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, 2-(perfluorobutyl)ethyl group, 2-(perfluorohexyl)ethyl group, 2-(perfluorooctyl)ethyl group, and 2-(perfluorodecyl)ethyl group.

[0343] Specific examples of repeating units represented by equations (4A) to (4E) are shown below, but are not limited to these. Note that in the following equations, RB This is the same as described above. [ka]

[0344] [ka]

[0345] [ka]

[0346] [ka]

[0347] [ka]

[0348] [ka]

[0349] The polymer-type surfactant may further contain other repeating units other than those represented by formulas (4A) to (4E). Examples of other repeating units include those obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. The content of the repeating units represented by formulas (4A) to (4E) in the polymer-type surfactant is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of the total repeating units.

[0350] The Mw of the polymer-type surfactant is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. The Mw / Mn ratio is preferably 1.0 to 2.0, and more preferably 1.0 to 1.6.

[0351] A method for synthesizing the polymer-type surfactant involves polymerizing a monomer containing unsaturated bonds that give repeating units represented by formulas (4A) to (4E), and optionally other repeating units, by heating it in an organic solvent with a radical initiator. Examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid-unstable group may be used as is after being introduced into the monomer, or it may be protected or partially protected after polymerization.

[0352] When synthesizing the polymer-type surfactant, known chain transfer agents such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In that case, the amount of these chain transfer agents added is preferably 0.01 to 10 mol% relative to the total number of moles of monomers to be polymerized.

[0353] If the resist composition of the present invention contains a surfactant (F), its content is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the base polymer (A). If the content of surfactant (F) is 0.1 parts by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, and if it is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is small, and the height of the formed fine pattern is sufficiently maintained. Surfactants (F) may be used alone or in combination of two or more types.

[0354] [(G) Other ingredients] The resist composition of the present invention may also contain (G) other components such as a compound that decomposes with acid to generate acid (acid-proliferating compound), an organic acid derivative, a fluorine-substituted alcohol, and a compound with an Mw of 3,000 or less whose solubility in the developer changes due to the action of acid (dissolution inhibitor). As the acid-proliferating compound, the compounds described in Japanese Patent Publication No. 2009-269953 or Japanese Patent Publication No. 2010-215608 can be referenced. When the acid-proliferating compound is included, its content is preferably 0 to 5 parts by mass, and more preferably 0 to 3 parts by mass, per 80 parts by mass of the (B) base polymer. If the content is too high, it becomes difficult to control acid diffusion, which may lead to deterioration of resolution and pattern shape. As the organic acid derivative, fluorine-substituted alcohol and dissolution inhibitor, the compounds described in Japanese Patent Publication No. 2009-269953 or Japanese Patent Publication No. 2010-215608 can be referenced.

[0355] [Pattern formation method] The pattern formation method of the present invention includes the steps of forming a resist film on a substrate using the resist composition described above, exposing the resist film with high-energy rays, and developing the exposed resist film using a developer.

[0356] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or substrates for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) can be used.

[0357] The resist film can be formed by, for example, applying the resist composition to a film thickness of preferably 0.05 to 2 μm using a method such as spin coating, and then pre-baking it on a hot plate at preferably 60 to 150°C for 1 to 10 minutes, more preferably 80 to 140°C for 1 to 5 minutes.

[0358] High-energy beams used for exposure of resist films include i-line, KrF excimer laser light, ArF excimer laser light, EB, and EUV. When using KrF excimer laser light, ArF excimer laser light, or EUV, exposure is performed using a mask to form the desired pattern, with an exposure dose of preferably 1 to 200 mJ / cm². 2 More preferably 10-100 mJ / cm² 2 This can be done by irradiating in such a manner. When using EB, the exposure amount is preferably 1 to 300 μC / cm², either using a mask to form the desired pattern or directly. 2 More preferably 10-200 μC / cm 2 Irradiate in such a way that it results in the following.

[0359] In addition to conventional exposure methods, immersion methods can also be used, in which a liquid with a refractive index of 1.0 or higher is interposed between the resist film and the projection lens. In this case, a protective film insoluble in water can also be used.

[0360] The aforementioned water-insoluble protective film is used to prevent leaching from the resist film and to improve the water-repellent properties of the film surface, and there are two main types. One is an organic solvent-removable type that requires removal before alkaline aqueous solution development using an organic solvent that does not dissolve the resist film, and the other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with the soluble parts of the resist film. The latter is particularly preferably based on a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and soluble in alkaline developer, and dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof. Alternatively, the aforementioned water-insoluble and alkaline developer-soluble surfactant can be dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof.

[0361] PEB may be performed after exposure. PEB can be performed, for example, by heating on a hot plate, preferably at 60-150°C for 1-5 minutes, more preferably at 80-140°C for 1-3 minutes.

[0362] Development is carried out using a developer solution, preferably an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) in an amount of 0.1 to 5% by mass, more preferably 2 to 3% by mass, and by conventional methods such as the dip method, puddle method, or spray method for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, which dissolves the exposed areas and forms the desired pattern on the substrate.

[0363] Furthermore, after the resist film is formed, a rinse with pure water may be performed to extract acid generators or other substances from the film surface, or to wash away particles. Alternatively, a rinse may be performed after exposure to remove any water remaining on the film.

[0364] Furthermore, patterns may be formed by a double patterning method. Examples of double patterning methods include the trench method, in which a 1:3 trench pattern base is processed with the first exposure and etching, and then a 1:3 trench pattern is formed by a second exposure with a shifted position to form a 1:1 pattern; and the line method, in which a first base for a 1:3 isolated pattern is processed with the first exposure and etching, and then a second exposure with a shifted position to process a second base formed beneath the first base for a 1:3 isolated pattern to form a 1:1 pattern with half the pitch.

[0365] In the pattern formation method of the present invention, a negative tone development method may be used in which an organic solvent is used as the developer to dissolve the unexposed areas instead of the alkaline aqueous solution. The organic solvent development may include, as the developer: 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, propyl formate, methyl methyl acetate, methyl methyl crotate, ethyl crotate, propyl methyl methyl methyl acetate, methyl methyl methyl acetate, methyl methyl methyl crotate, methyl methyl methyl methyl chlorotate,chlorotate, methyl methyl methyl chlorotate, methyl methyl chlorotate, methyl methyl methyl chlorotate, methyl methyl methyl chlorotate, methyl methyl methyl chlorotate, Methyl ropionate, 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, ethyl phenyl acetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, etc. can be used. These organic solvents may be used individually or in mixtures of two or more. [Examples]

[0366] 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 apparatus used is as follows. • MALDI TOF-MS: S3000 manufactured by JEOL Ltd.

[0367] [1] Synthesis of onium salts [Example 1-1] Synthesis of onium salt NSQ-1 [ka]

[0368] (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, compound SM-1 (24.3g), ethyl 4-aminobenzoate (17.3g), 4-dimethylaminopyridine (DMAP) (1.2g), and methylene chloride (100g) were charged into a reaction vessel and cooled in an ice bath. While maintaining the temperature inside the reaction vessel below 20°C, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (23.0g) was added in powder form. After addition, the temperature was raised to room temperature and aged for 12 hours. After aging, water was added to stop the reaction, and a normal aqueous work-up was performed. After removing the solvent by distillation, hexane was added and recrystallization was performed to obtain the intermediate In-1 as white crystals (yield 36.7g, yield 94%).

[0369] (2) Synthesis of intermediate In-2 Under a nitrogen atmosphere, intermediate In-1 (36.7 g) was dissolved in THF (120 g). Then, 25% by mass aqueous sodium hydroxide solution (15.8 g) was added dropwise. After the dropwise addition, the reaction mixture was heated to 40°C and aged for 4 hours. After aging, the reaction system was cooled to room temperature, the solvent was removed by distillation, and then diisopropyl ether was added and recrystallization was performed to obtain intermediate In-2 as white crystals (yield 31.1 g, yield 86%).

[0370] (3) Synthesis of onium salt NSQ-1 Under a nitrogen atmosphere, intermediate In-2 (19.2 g) and triphenylsulfonium bromide (20.6 g) were mixed with methylene chloride (100 g) and water (80 g), and stirred at room temperature for 2 hours. After stirring, a normal aqueous work-up was performed, and the solvent was removed by distillation to obtain onium salt NSQ-1 as an oily substance (yield 28.4 g, yield 91%).

[0371] The TOF-MS results for onium salt NSQ-1 are shown below. MALDI TOF-MS: POSITIVE M + 263(C 18 H 15 S + equivalent) NEGATIVE M - 361(C 19 H 25N2O5 - equivalent)

[0372] [Examples 1-2 to 1-7] Synthesis of onium salts NSQ-2 to NSQ-7 Using corresponding raw materials and known organic chemical reactions, salt quenchers NSQ-2 to NSQ-7, represented by the following formulas, were synthesized. [ka]

[0373] [ka]

[0374] [Synthesis Example] Synthesis of base polymers (polymers P-1 to P-5) Each monomer was combined and copolymerized in MEK, a solvent. The mixture was then placed in hexane, and the precipitated solid was washed with hexane, isolated, and dried to obtain base polymers (polymers P-1 to P-5) with the following compositions. The compositions of the obtained base polymers are: 1 Mw and Mw / Mn were confirmed by H-NMR using GPC (solvent: DMF, standard: polystyrene). [ka]

[0375] [3] Preparation of resist composition [Examples 2-1 to 2-20, Comparative Examples 1-1 to 1-12] A resist composition was prepared by dissolving the onium salts (NSQ-1 to NSQ-6), comparative quenchers (SQ-A to SQ-D, AQ-A), base polymers (P-1 to P-5), and photoacid generators (PAG-1, PAG-2) of the present invention in a solvent containing 100 ppm of FC-4430 manufactured by 3M as a surfactant, in the compositions shown in Tables 1 and 2 below. The solution was then filtered through a 0.2 μm Teflon® filter to prepare the resist composition.

[0376] In Tables 1 and 2, the components are as follows: • Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol)

[0377] • Photoacid generators: PAG-1, PAG-2 [ka]

[0378] • Quenchers for comparison: SQ-A~SQ-D, AQ-A [ka]

[0379] [Table 1]

[0380] [Table 2]

[0381] [4] EUV lithography evaluation (1) [Examples 3-1 to 3-20, Comparative Examples 2-1 to 2-12] Each chemically amplified resist composition (R-1 to R-20, CR-1 to CR-12) was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm. A resist film with a thickness of 50 nm was then fabricated by pre-baking at 100°C for 60 seconds using a hot plate. The resist film was then exposed to an LS pattern with a wafer dimension of 18 nm and a pitch of 36 nm using an ASML EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, dipole illumination), with exposure dose and focus varied (exposure dose pitch: 1 mJ / cm²). 2The process was carried out while adjusting the focus pitch (0.020 μm), and after exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 3 and 4. Then, paddle development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution, rinsed with a surfactant-containing rinse material, and spin-dried to obtain a positive type pattern. The developed LS patterns were observed using a Hitachi High-Technologies Corporation length-measuring SEM (CG6300), and sensitivity, EL, LWR, DOF, and tilt limit were evaluated according to the method described below. The results are shown in Tables 3 and 4.

[0382] [Sensitivity evaluation] Optimal exposure amount E for obtaining an LS pattern with a line width of 18 nm and a pitch of 36 nm op (mJ / cm 2 We calculated this value and defined it as the sensitivity.

[0383] [EL rating] The exposure amount formed within ±10% (16.2 to 19.8 nm) of the 18 nm space width in the aforementioned LS pattern was used to calculate the EL (unit: %) using the following formula. A larger value indicates better performance. EL(%)=(|E1-E2| / E op ) × 100 E1: Optimal exposure amount to give an LS pattern with a line width of 16.2 nm and a pitch of 36 nm. E2: Optimal exposure amount to give an LS pattern with a line width of 19.8 nm and a pitch of 36 nm. E op : Optimal exposure amount to give an LS pattern with a line width of 18nm and a pitch of 36nm

[0384] [LWR rating] E op The LS pattern obtained by irradiation was measured at 10 points along the longitudinal direction of the line, and the LWR was calculated as three times the standard deviation (σ) (3σ) from the results. The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0385] [DOF rating] To evaluate the depth of focus, the focus range formed within ±10% of the 18nm dimension (16.2 to 19.8nm) in the aforementioned LS pattern was determined. A larger value indicates a wider depth of focus.

[0386] [Evaluation of the limit of line pattern collapse] The line dimensions for each exposure amount at the optimal focus of the aforementioned LS pattern were measured at 10 points along the longitudinal direction. The thinnest line dimension obtained without collapse was defined as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0387] [Table 3]

[0388] [Table 4]

[0389] The results shown in Tables 3 and 4 confirm that the resist composition of the present invention exhibits good sensitivity, excellent performance in various lithography techniques, and strong resistance to pattern deformation.

[0390] [5] EUV Lithography Evaluation (2) [Examples 4-1 to 4-20, Comparative Examples 3-1 to 3-12] Each chemically amplified resist composition (R-1 to R-20, CR-1 to CR-12) was spin-coated onto a Si substrate on which Shin-Etsu Chemical Co., Ltd.'s silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) had been formed to a thickness of 20 nm. The resist films were then pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 60 nm. Next, the resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, wafer-mounted dimensions of a 44 nm pitch hole pattern mask with a +20% bias). PEB was performed on a hot plate at the temperatures listed in Tables 5 and 6 for 60 seconds, and development was performed with a 2.38 mass% TMAH aqueous solution for 30 seconds. Examples 4-1 to 4-18 and Comparative Examples 3-1 to 3-10 yielded hole patterns with dimensions of 22 nm, while Examples 4-19, 4-20 and Comparative Examples 3-11 and 3-12 yielded dot patterns with dimensions of 22 nm. Using a length-measuring SEM (CG6300) manufactured by Hitachi High-Tech Corporation, the exposure amount when 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 that time were also measured, and the CDU was defined as three times the standard deviation (σ) calculated from the results (3σ). The results are shown in Tables 5 and 6.

[0391] [Table 5]

[0392] [Table 6]

[0393] The results shown in Tables 5 and 6 confirm that the chemically amplified resist composition containing the quencher of the present invention exhibits good sensitivity in both positive and negative resists and has excellent CDU properties.

Claims

1. The onium salt represented by the following formula (1). 【Chemistry 1】 [In the formula, n1 is an integer between 0 and 1. n2 is an integer between 0 and 6. n3 is 0. n4 is an integer between 0 and 4.] W is a nitrogen-containing aliphatic heterocycle having 2 to 20 carbon atoms, which may contain heteroatoms. L A and L B These are, independently, a single bond, an ether bond, an ester bond, an amide bond, a sulfonic acid ester bond, a carbonate bond, or a carbamate bond. X L This is a hydroxylene group having 1 to 40 carbon atoms, which may contain single bonds or heteroatoms. R 1 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. When n2 ≥ 2, multiple R 1 However, they may bond to each other and form a ring together with the carbon atoms on the W to which they are bonded. R 2 This is a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. When n4≧2, multiple R 2 However, they may bond with each other to form a ring together with the carbon atoms on the aromatic ring to which they are bonded. R AL It is an acid-unstable group that undergoes a deprotection reaction with strong acids. Z + is an onium cation represented by any one of the following formulas (cation-1) to (cation-3). 【Chemistry 2】 (In the formula, R 11 ~R 19 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain heteroatoms. Also, R 11 and R 12 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

2. R AL The onium salt according to claim 1, wherein the group is represented by the following formula (AL-1) or (AL-2). 【Transformation 3】 (In the formula, L c It is either -O- or -S-. R 3 , R 4 and R 5 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms. Also, R 3 , R 4 and R 5 Any two of these may be joined together to form a ring. R 6 and R 7 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 8 This is a hydrocarbyl group having 1 to 20 carbon atoms, and the -CH of the hydrocarbyl group 2 - may be replaced with -O- or -S-. Also, R 7 and R 8 and are bonded to each other, and the carbon atoms and L that they bond to are bonded to. c Together, a heterocyclic group having 3 to 20 carbon atoms may be formed, and the -CH of the heterocyclic group 2 The - may be replaced with -O- or -S-. m1 and m2 are independently either 0 or 1. * represents a bond with an adjacent -O-.

3. The onium salt according to claim 1, wherein W is represented by any of the following formulas. 【Chemistry 4】 (In the formula, * represents L) A This represents a bond with R, where ** is R AL (This represents a bond between -O-C(=O)-.)

4. The onium salt according to claim 1, which is represented by the following formula (1A). 【Transformation 5】 (In the formula, n1 to n4, W, L B , R 1 , R 2 , R AL and Z + (This is the same as above.)

5. The onium salt according to claim 4, which is represented by the following formula (1B). 【Transformation 6】 (In the formula, n1, n2, n4, W, L B , R 1 , R 2 , R AL and Z + (This is the same as above.)

6. A quencher comprising an onium salt according to any one of claims 1 to 5.

7. A resist composition comprising the quencher according to claim 6.

8. Furthermore, the resist composition according to claim 7, further comprising an organic solvent.

9. The resist composition according to claim 7, comprising a base polymer containing repeating units represented by the following formula (a1). 【Transformation 7】 (In the formula, R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X 11 - and the phenylene group or naphthylene group may be substituted with a carbon-1 to carbon-10 alkoxy group or halogen atom which may contain a fluorine atom. 11 This is a saturated hydrocarbylene group, phenylene group, or naphthylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. The saturated hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. * indicates a bond with a carbon atom of the main chain. AL 1 It is an acid-unstable group.

10. The resist composition according to claim 9, wherein the base polymer further comprises repeating units represented by the following formula (a2). 【Transformation 8】 (In the formula, R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 2 The bond is either a single bond or *-C(=O)-O-. The asterisk (*) represents a bond with a carbon atom in the main chain. R 21 This is a C1-C20 hydrocarbyl group which may contain a halogen atom, a cyano group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. AL 2 It is an acid-unstable group. (a is an integer between 0 and 4.)

11. The resist composition according to claim 9, wherein the base polymer further comprises repeating units represented by the following formula (b1) or (b2). 【Chemistry 9】 (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 The bond is either a single bond or *-C(=O)-O-. The asterisk (*) represents a bond with a carbon atom in the main chain. R 22 This is a group having 1 to 20 carbon atoms that includes a hydrogen atom or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride (-C(=O)-O-C(=O)-). R 23 This refers to a C1-C20 hydrocarbyl group which may contain a halogen atom, a hydroxyl group, a nitro group, a heteroatom, a C1-C20 hydrocarbyloxy group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyl group which may contain a heteroatom, a C2-C20 hydrocarbylcarbonyloxy group which may contain a heteroatom, or a C2-C20 hydrocarbyloxycarbonyl group which may contain a heteroatom. b is an integer between 1 and 4. c is an integer between 0 and 4. However, 1 ≤ b + c ≤ 5.

12. The resist composition according to claim 9, wherein the base polymer further comprises a repeating unit represented by any of the following formulas (c1) to (c4). 【Chemistry 10】 (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 This is either a single bond or a phenylene group. Z 2 *-C(=O)-O-Z 21 -, *-C(=O)-NH-Z 21 - or * - O - Z 21 - is Z 21 This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z 3 These are, independently, a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-Z. 31 - is Z 31 This is an aliphatic hydrocarbylene group, a phenylene group, or a naphthylene group having 1 to 10 carbon atoms, and the aliphatic hydrocarbylene group may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring. Z 4 Each of these is independently a single bond, *-Z 41 -C(=O)-O-, *-C(=O)-NH-Z 41 - or * - O - Z 41 - is. is. Z 41 This is a hydrocarbylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Z 5 Each of these is independently a single bond, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 - or * - O - Z 51 - is Z 51 This is a hydrocarbylene group having 1 to 20 carbon atoms, which may contain heteroatoms. Z 6 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-O-Z. 61 -, *-C(=O)-N(H)-Z 61 - or * - O - Z 61 - is Z 61 This is a phenylene group substituted with an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond with a carbon atom in the main chain. R 31 and R 32 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Also, R 31 and R 32 These may bond with each other to form a ring with the sulfur atom to which they are bonded. L 1 These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Rf 1 and Rf 2 Each of these is independently either a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. However, all of the Rf 5 and Rf 6 do not simultaneously become hydrogen atoms. M - is a non-nucleophilic counter ion. A + This is an onium cation. d is an integer between 0 and 3.

13. Furthermore, the resist composition according to claim 7, further comprising a photoacid generator.

14. Furthermore, the resist composition according to claim 7, further comprising a quencher other than the quencher described in claim 6.

15. Furthermore, the resist composition according to claim 7, further comprising a surfactant.

16. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist material described in claim 7; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

17. The pattern formation method according to claim 16, wherein 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.

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