Sulfonium salt, resist material, and pattern formation method

Abstract

To provide a resist material that has high sensitivity and improved LWR and CDU, regardless of whether it is a positive or negative type, and a patterning method using the same.SOLUTION: The present invention provides a sulfonium salt represented by the formula (1), and a resist material containing the sulfonium salt.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to sulfonium salts, resist materials, 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 spread of 5G high-speed communication and artificial intelligence (AI) is advancing, requiring 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, EUV lithography is also being explored for next-generation 3nm node and the following-generation 2nm node devices, and IMEC in Belgium has announced the development of 1nm and 0.7nm 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 dissolution contrast as has been conventionally proposed (Non-Patent Literature 1). However, since chemically amplified resist materials increase sensitivity and contrast through acid diffusion, attempting to suppress acid diffusion to the extreme by lowering the post-exposure bake (PEB) temperature or shortening the time results in a significant decrease in sensitivity and contrast.

[0004] The triangle trade-off relationship between sensitivity, resolution, and edge roughness (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] Acid-unstable groups used in (meth)acrylate polymers for EUV and ArF resist materials undergo deprotection reactions by using a photoacid generator that produces sulfonic acid with a fluorine atom substituted at the α-position. However, deprotection reactions do not proceed with acid generators that produce sulfonic acid or carboxylic acid without a fluorine atom substituted at the α-position. When a sulfonium salt or iodonium salt that produces sulfonic acid with a fluorine atom substituted at the α-position is mixed with a sulfonium salt or iodonium salt that produces sulfonic acid without a fluorine atom substituted at the α-position, the sulfonium salt or iodonium salt that produces sulfonic acid without a fluorine atom substituted at the α-position undergoes ion exchange with the sulfonic acid with a fluorine atom substituted at the α-position. Since the sulfonic acid with a fluorine atom substituted at the α-position generated by light reverts back to the sulfonium salt or iodonium salt through ion exchange, the sulfonium salt or iodonium salt of sulfonic acid or carboxylic acid without a fluorine atom substituted at the α-position functions as a quencher. A resist material has been proposed that uses a sulfonium salt or iodonium salt that generates a carboxylic acid as a quencher (Patent Document 3).

[0007] Sulfonium salt type quenchers that generate carboxylic acids have been proposed. For example, sulfonium salts of salicylic acid and β-hydroxycarboxylic acid (Patent Document 4), salicylic acid derivatives (Patent Documents 5 and 6), fluorosalicylic acid (Patent Document 7), hydroxynaphthoic acid (Patent Document 8), and sulfonium salts of thiol carboxylic acids (Patent Document 9) have been proposed. In particular, salicylic acid is highly effective in suppressing acid diffusion through intramolecular hydrogen bonding between the carboxyl group and the hydroxyl group.

[0008] A sulfonium salt (Patent Document 10) has been proposed that combines a carboxylic acid anion with a phenyldibenzothiophenium cation substituted with a carbonyl group or an alkoxycarbonyl group. Examples of carboxylic acid anions include adamantane carboxylic acid or its analogues, salicylic acid, and fluoroalkyl carboxylic acids. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2006-045311 [Patent Document 2] Japanese Patent Publication No. 2006-178317 [Patent Document 3] Japanese Patent Publication No. 2007-114431 [Patent Document 4] International Publication No. 2018 / 159560 [Patent Document 5] Japanese Patent Publication No. 2020-203984 [Patent Document 6] Japanese Patent Publication No. 2020-91404 [Patent Document 7] Japanese Patent Publication No. 2020-91312 [Patent Document 8] Japanese Patent Publication No. 2019-120760 [Patent Document 9] Japanese Patent Publication No. 2019-74588 [Patent Document 10] Japanese Patent Publication No. 2021-035937 [Non-patent literature]

[0010] [Non-Patent Document 1] SPIE Vol. 6520 65203L-1 (2007) [Overview of the project] [Problems that the invention aims to solve]

[0011] In resist materials, there is a need for the development of a quencher that can improve the LWR of line patterns and the dimensional uniformity (CDU) of hole patterns, while also enhancing sensitivity. To achieve this, it is necessary to further reduce image blurring caused by acid diffusion.

[0012] This invention has been made in view of the above circumstances, and aims to provide a resist material that is highly sensitive and has improved LWR and CDU, whether it is positive or negative type, and a pattern formation method using the same. [Means for solving the problem]

[0013] The inventors, through diligent research to achieve the above objective, have found that sulfonium salts comprising a carboxylic acid anion having a hydroxyl group bonded to carbon atoms other than the carbon atoms of the aromatic ring, a fluorine atom or a trifluoromethyl group at the α or β position, and a sulfonium cation of a specific structure such as a phenyldibenzothiophenium cation having a hydrocarbyl carbonyl group or a hydrocarbyloxycarbonyl group, have high acid diffusion control ability due to the presence of a hydroxyl group bonded to carbon atoms other than the carbon atoms of the aromatic ring, and are useful as quenchers. Furthermore, the inventors have found that the sulfonium salts also have high uniform dispersibility within the resist film because aggregation is suppressed due to the electrical repulsion of the fluorine atom of the carboxylic acid anion and high solubility in organic solvents. Phenyldibenzothiophenium cations having the electron-withdrawing groups hydrocarbyl carbonyl group or hydrocarbyloxycarbonyl group have high decomposition efficiency during exposure and are highly effective in suppressing acid diffusion. By using the aforementioned sulfonium salt as a quencher, we discovered that a resist material with high sensitivity, improved LWR and CDU, excellent resolution, and a wide process margin can be obtained, thus completing the present invention.

[0014] In other words, the present invention provides the following sulfonium salts, resist materials, and pattern forming methods. 1. A sulfonium salt represented by the following formula (1). [ka] (In the formula, p, q, and r are each independent integers between 0 and 3, and s is either 1 or 2.) R 1 and R 2 These are, independently, a halogen atom, a trifluoromethyl group, a trifluoromethoxy group, a trifluoromethylthio group, a nitro group, a cyano group, and a -C(=O)-R group. 4 -OC(=O)-R 5 OR 5 That is the case. R 3is a halogen atom, a trifluoromethyl group, a trifluoromethoxy group, a trifluoromethylthio group, a nitro group, a cyano group, -O-C(=O)-R 5 or -O-R 5 is. R 4 is a hydrocarbyl group having 1 to 10 carbon atoms, a hydrocarbyloxy group having 1 to 10 carbon atoms or -O-R 4A is, and the hydrocarbyl group and the hydrocarbyloxy group may be substituted with a fluorine atom or a hydroxy group. R 4A is an acid-labile group. R 5 is a hydrocarbyl group having 1 to 10 carbon atoms. X 1 is a single bond, an ether group, a carbonyl group, -N(R)-, a sulfide group bond or a sulfonyl group. R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. Xq - is a carboxylic acid anion having a hydroxy group bonded to a carbon atom other than the carbon atom of the aromatic ring and a fluorine atom or a trifluoromethyl group at the α-position or β-position.) 2. The sulfonium salt of 1 in which the carboxylic acid anion is represented by the following formula (2).

Chemical formula

[0015] The sulfonium salt of the present invention is a quencher that suppresses acid diffusion. The sulfonium salt of the present invention has low acid diffusion properties, making it possible to construct resist materials with low LWR and improved CDU. [Modes for carrying out the invention]

[0016] [Sulfonium salt] The sulfonium salt of the present invention (hereinafter also referred to as sulfonium salt A) is represented by the following formula (1). [ka]

[0017] In equation (1), p, q, and r are each independent integers between 0 and 3, and s is either 1 or 2, where 1 ≤ r + s ≤ 3.

[0018] In formula (1), R 1 and R 2 These are, independently, a halogen atom, a trifluoromethyl group, a trifluoromethoxy group, a trifluoromethylthio group, a nitro group, a cyano group, and a -C(=O)-R group. 4 -OC(=O)-R 5 OR 5 That is the case.

[0019] In formula (1), R 3 This includes halogen atoms, trifluoromethyl groups, trifluoromethoxy groups, trifluoromethylthio groups, nitro groups, cyano groups, and -OC(=O)-R 5 OR 5 That is the case.

[0020] In formula (1), R 4 This refers to a hydrocarbyl group having 1 to 10 carbon atoms, a hydrocarbyloxy group having 1 to 10 carbon atoms, or -OR 4A The hydrocarbyl group and the hydrocarbyloxy group may be substituted with a fluorine atom or a hydroxyl group. 4A It is an acid-unstable group.

[0021] R 5 This is a hydrocarbyl group having 1 to 10 carbon atoms.

[0022] R 4 and R 5 A hydrocarbyl group represented by R 4The hydrocarbyl group of the hydrocarbyloxy group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, 3-pentyl, tert-pentyl, neopentyl, n-hexyl, n-octyl, n-nonyl, and n-decyl; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, norbornyl, and cyclopropyl groups. Cyclopropylmethyl group, cyclopropylethyl group, cyclobutylmethyl group, cyclobutylethyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclohexylmethyl group, cyclohexylethyl group, methylcyclopropyl group, methylcyclobutyl group, methylcyclopentyl group, methylcyclohexyl group, ethylcyclopropyl group, ethylcyclobutyl group, ethylcyclopentyl group, ethylcyclohexyl group, etc., cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms; vinyl group, 1-propene Alkenyl groups with 2 to 10 carbon atoms, such as nyl group, 2-propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, nonenyl group, and decenyl group; Alkynyl groups with 2 to 10 carbon atoms, such as ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octinyl group, noninyl group, and decinyl group; Cyclopentenyl group, cyclohexenyl group, methylcyclopentenyl group, methylcyclohexenyl group, ethylcyclopentenyl group, ethylcyclohexenyl group, norbol Examples include cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 10 carbon atoms, such as the nenyle group; aryl groups with 6 to 10 carbon atoms, such as the phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, and naphthyl group; aralkyl groups with 7 to 10 carbon atoms, such as the benzyl group, phenethyl group, phenylpropyl group, and phenylbutyl group; and groups obtained by combining these.

[0023] R 4AAs the acid-unstable group represented by the formulas (AL-1) to (AL-3) described later, conventionally known groups used in resist materials can be used.

[0024] In formula (1), X 1 R is a single bond, ether bond, carbonyl group, -N(R)-, sulfide bond, or sulfonyl group. R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms.

[0025] Examples of cations of the sulfonium salt represented by formula (1) include, but are not limited to, those listed below. [ka]

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] Preferably, the sulfonium cation is a dibenzothiophenium salt, i.e., X in formula (1). 1 The bond is a single bond, which is particularly suitable for EUV lithography due to its high photodegradation efficiency. More preferably, the substituent of the cation is an ester bond, i.e., R in formula (1) 4 The group is an alkoxy group. In this case, the ester portion is hydrolyzed, especially during alkaline development, which improves the solubility of the exposed area and suppresses residue defects.

[0037] In formula (1), Xq - This is a carboxylic acid anion having a hydroxyl group bonded to a carbon atom other than the carbon atom of the aromatic ring, and a fluorine atom or a trifluoromethyl group at the α or β position. The anion represented by the following formula (2) is preferred as such. [ka]

[0038] In equation (2), n is either 0 or 1.

[0039] In formula (2), R 6 ~R 9These are, independently, a hydrogen atom, a fluorine atom, and a trifluoromethyl group, but when n is 0, R 6 and R 7 At least one of them is a fluorine atom or a trifluoromethyl group, and when n is 1, R 6 ~R 9 At least one of them is a fluorine atom or a trifluoromethyl group.

[0040] In formula (2), R 10This is a hydroxylene group having 1 to 20 carbon atoms, which may contain single bonds or heteroatoms. The hydroxylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. 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-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8- Alkane diyl groups with 1 to 20 carbon atoms, such as diyl groups, nonane-1,9-diyl groups, decane-1,10-diyl groups, undecane-1,11-diyl groups, and dodecane-1,12-diyl groups; cyclic saturated hydrocarbylene groups with 3 to 20 carbon atoms, such as cyclopentanediyl groups, cyclohexanediyl groups, norbornanediyl groups, and adamantanediyl groups; alkane diyl groups and cyclic saturated hydro Examples include divalent groups with 4 to 20 carbon atoms obtained by combining with a locarbylene group; and divalent groups with 7 to 20 carbon atoms obtained by combining an arylene group with 6 to 20 carbon atoms, such as a phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, tert-butylnaphthylene group, etc., with at least one selected from an alkanediyl group and a cyclic saturated hydrocarbylene group.Also, 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, a sulfur atom, a nitrogen atom, or a halogen atom, and a part of -CH2- of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. However, the carbon atom in R where -OH is bonded is not a carbon atom of an aromatic ring. 10 The carbon atom in 10 is not a carbon atom of an aromatic ring.

[0041] Also, R 10 is preferably a group represented by the following formula (2)-1.

Chemical formula

[0042] In formula (2)-1, R 10A and R 10B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof are R 4 and R 5Examples thereof include the same ones as those exemplified as the hydrocarbyl group represented by . Further, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0043] Also, R 10A and R 10B may be bonded to each other to form a ring together with the carbon atom to which they are bonded. Examples of the ring formed at this time include a cyclopropane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc.

[0044] In formula (2)-1, R 10C is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms which may contain a hetero atom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include those having 1 to 10 carbon atoms among those exemplified as the hydrocarbylene group represented by . Further, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. However, for R 10C ​​The carbon atoms inside are not the carbon atoms of the aromatic ring.

[0045] In the carboxylic acid anion represented by formula (2), n is 0, and R 10 It is a single bond, R 6 and R 7 It is preferable that the group is a trifluoromethyl group.

[0046] Furthermore, the number of carbon atoms in the group represented by formula (2)-1 is 20 or less.

[0047] The anions represented by formula (2) include, but are not limited to, those listed below. [ka]

[0048] One method for synthesizing sulfonium salt A is to exchange a sulfonium salt having the aforementioned sulfonium cation with an ammonium salt of the aforementioned anion or a protonic acid of the aforementioned anion through ion exchange. The aforementioned sulfonium cation can be obtained, for example, by the reaction of a dibenzothiophene compound having a carbonyl group or an alkoxycarbonyl group with a diphenyliodonium salt.

[0049] [Resist material] The resist material of the present invention is characterized by comprising a quencher containing sulfonium salt A.

[0050] In the resist material of the present invention, the content of sulfonium salt A is preferably 0.001 to 50 parts by mass, and more preferably 0.01 to 40 parts by mass, per 100 parts by mass of the base polymer described later. Sulfonium salt A may be used alone or in combination of two or more types.

[0051] [Base polymer] The resist material of the present invention may include a base polymer. In the case of a positive-type resist material, the base polymer includes repeating units containing acid-unstable groups. The repeating units containing acid-unstable groups are preferably the repeating units represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or the repeating units represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0052] In equations (a1) and (a2), R A Each of these is independently either a hydrogen atom or a methyl group. 1 This is a linking group having 1 to 12 carbon atoms, containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond and a lactone ring. 2 These are single bonds or ester bonds. 3 These are single bonds, ether bonds, or ester bonds. 11 and R 12 These are, independently, acid-unstable groups. Furthermore, if the base polymer contains both repeating unit a1 and repeating unit a2, R 11 and R 12 These may be identical or different from one another. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 14 a is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and some of its carbon atoms may be substituted with ether or ester bonds. a is 1 or 2. b is an integer from 0 to 4, where 1 ≤ a + b ≤ 5.

[0053] Examples of monomers that give repeating unit a1 are listed below, but are not limited to these. Note that in the following formula, R A and R 11 This is the same as described above. [ka]

[0054] Examples of monomers that give repeating units a2 are listed below, but are not limited to these. Note that in the following formula, R A and R 12 This is the same as described above. [ka]

[0055] In equations (1), (a1), and (a2), R 4A , R 11 and R 12 Examples of acid-unstable groups represented by include those described in Japanese Patent Publication No. 2013-80033 and Japanese Patent Publication No. 2013-83821.

[0056] Typically, the acid-unstable groups mentioned above are those represented by the following formulas (AL-1) to (AL-3). [ka] (In the equation, dashed lines represent connections.)

[0057] In equations (AL-1) and (AL-2), R L1 and R L2 Each of these is independently a hydrocarbyl group having 1 to 40 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A saturated hydrocarbyl group having 1 to 40 carbon atoms is preferred, and a saturated hydrocarbyl group having 1 to 20 carbon atoms is more preferred.

[0058] In formula (AL-1), c is an integer between 0 and 10, preferably between 1 and 5.

[0059] In formula (AL-2), R L3 and R L4Each of these is independently a hydrogen atom or a C1-C20 hydrocarbyl group, and may contain heteroatoms such as oxygen, sulfur, nitrogen, or fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A saturated hydrocarbyl group having C1-C20 is preferred as the hydrocarbyl group. 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 with an oxygen atom. The ring is preferably a ring having 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0060] In formula (AL-3), R L5 , R L6 and R L7 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A saturated hydrocarbyl group having 1 to 20 carbon atoms is preferred as the hydrocarbyl group. 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.

[0061] The base polymer may contain repeating unit b having a phenolic hydroxyl group as an adhesion group. Examples of monomers that give repeating unit b are, but are not limited to, those listed below. In the following formula, R A This is the same as described above. [ka]

[0062] [ka]

[0063] [ka]

[0064] The base polymer may also contain repeating units c as other adhesive groups, including hydroxyl groups other than phenolic hydroxyl groups, lactone rings, sultone rings, ether bonds, ester bonds, sulfonic acid ester bonds, carbonyl groups, sulfonyl groups, cyano groups, or carboxyl groups. Examples of monomers that give repeating units c are, but are not limited to, those listed below. In the following formula, R A This is the same as described above. [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] The base polymer may contain repeating units d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Examples of monomers that give repeating units d are, but are not limited to, those listed below. [ka]

[0074] The base polymer may contain repeating units e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindan, vinylpyridine, or vinylcarbazole.

[0075] The base polymer may contain repeating units f derived from an onium salt containing polymerizable unsaturated bonds. Preferred repeating units f include the repeating unit represented by the following formula (f1) (hereinafter also referred to as repeating unit f1), the repeating unit represented by the following formula (f2) (hereinafter also referred to as repeating unit f2), and the repeating unit represented by the following formula (f3) (hereinafter also referred to as repeating unit f3). Repeating units f1 to f3 may be used individually or in combination of two or more types. [ka]

[0076] In formulas (f1) to (f3), R A Each of these is independently either a hydrogen atom or a methyl group. 1This refers to a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 -or -C(=O)-NH-Z 11 - is Z 11 This is an aliphatic hydrocarbylene group, phenylene group, naphthylene group having 1 to 6 carbon atoms, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 2 These are single bonds or ester bonds. 3 This is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)- Z 31 This is an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, a urethane bond, a nitro group, a cyano group, a fluorine atom, an iodine atom, or a bromine atom. 4 This is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, phenylene groups substituted with trifluoromethyl groups, -OZ 51 -, -C(=O)-OZ 51 -or -C(=O)-NH-Z 51 - is Z 51 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, a halogen atom, or a hydroxyl group.

[0077] In formulas (f1) to (f3), R 21 ~R 28Each of these is a hydrocarbyl group having 1 to 20 carbon atoms, which may independently contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples of the halogen atom and hydrocarbyl group are given in the explanation of formulas (3-1) and (3-2) below, where R is used. 101 ~R 105 Examples of halogen atoms and hydrocarbyl groups represented by are similar to those exemplified. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, it may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc. 23 and R 24 or R 26 and R 27 However, they may bond to each other and form a ring with the sulfur atom to which they are bonded. In this case, the ring is R as described in the explanation of formulas (3-1) and (3-2) below. 101 and R 102 Examples include rings that can be formed when these elements bond to each other, together with the sulfur atom to which they bond.

[0078] In formula (f1), M -This is a non-nucleophilic counterion. 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.

[0079] Other examples of the aforementioned non-nucleophilic counterions include a sulfonate ion in which the α-position is substituted with a fluorine atom, represented by the following formula (f1-1), and a sulfonate ion in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group, represented by the following formula (f1-2). [ka]

[0080] In formula (f1-1), R 31 R is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (3A') described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0081] In formula (f1-2), R 32R is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 6 to 20 carbon atoms, and the hydrocarbyl group and hydrocarbylcarbonyl group may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl portion of the hydrocarbyl group and hydrocarbylcarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (3A') described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0082] Examples of monomer cations that give repeating units f1 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]

[0083] Specific examples of monomer cations that give repeating units f2 or f3 include those exemplified as cations of sulfonium salts represented by formula (1) and those similar to those exemplified as cations of sulfonium salts represented by formula (3-1) described later.

[0084] Examples of monomer anions that give the repeating unit f2 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]

[0085] [ka]

[0086] [ka]

[0087]

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[0088]

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[0089]

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[0090]

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[0091]

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[0092]

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[0093]

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[0094]

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[0095]

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[0096]

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[0097]

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[0098]

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[0099]

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[0100]

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[0101]

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[0102]

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[0103]

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[0104]

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[0105]

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[0106]

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[0107]

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[0108]

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[0109]

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[0110]

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[0111]

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[0112]

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[0113]

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[0114]

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[0115]

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[0116]

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[0117]

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[0118]

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[0119]

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[0120]

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[0121]

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[0122]

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[0123]

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[0124]

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[0125]

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[0126]

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[0127]

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[0128]

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[0129]

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[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] Examples of monomer anions that give repeating units f3 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]

[0135] The repeating units f1 to f3 function as acid generators. By binding the acid generator to the polymer backbone, acid diffusion is reduced, preventing a decrease in resolution due to blurring caused by acid diffusion. Furthermore, the uniform dispersion of the acid generator improves LWR and CDU. When using a base polymer containing repeating unit f, the addition of the additive-type acid generator described later can be omitted.

[0136] In the base polymer, the content ratios of repeating units a1, a2, b, c, d, e, f1, f2, and f3 are preferably 0≦a1≦0.9, 0≦a2≦0.9, 0≦a1+a2≦0.9, 0≦b≦0.9, 0≦c≦0.9, 0≦d≦0.5, 0≦e≦0.5, 0≦f1≦0.5, 0≦f2≦0.5, 0≦f3≦0.5, and 0≦f1+f2+f3≦0.5, and 0≦a1≦0.8, 0≦a2≦0.8, 0≦a1+a2≦0.8, 0 More preferably, the following are the conditions: ≤b≦0.8, 0≦c≦0.8, 0≦d≦0.4, 0≦e≦0.4, 0≦f1≦0.4, 0≦f2≦0.4, 0≦f3≦0.4, 0≦f1+f2+f3≦0.4. Even more preferably, the conditions are: 0≦a1≦0.7, 0≦a2≦0.7, 0≦a1+a2≦0.7, 0≦b≦0.7, 0≦c≦0.7, 0≦d≦0.3, 0≦e≦0.3, 0≦f1≦0.3, 0≦f2≦0.3, 0≦f3≦0.3, 0≦f1+f2+f3≦0.3, where a1+a2+b+c+d+f1+f2+f3+e=1.0.

[0137] One example of a method for synthesizing the base polymer is to heat a monomer that provides the repeating units mentioned above in an organic solvent with a radical polymerization initiator, and carry out polymerization.

[0138] Organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0139] When copolymerizing monomers containing hydroxyl groups, the hydroxyl groups may be substituted with acetal groups that are easily deprotected by acids such as ethoxyethoxy groups during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, they may be substituted with acetyl groups, formyl groups, pivaloyl groups, etc., and then subjected to alkaline hydrolysis after polymerization.

[0140] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to obtain hydroxystyrene or hydroxyvinylnaphthalene.

[0141] 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.

[0142] The base polymer has a polystyrene-based weight-average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30,000, determined by gel permeation chromatography (GPC) using THF as a solvent. When Mw is within this range, the heat resistance and solubility in alkaline developers of the resist film are good.

[0143] Furthermore, if the molecular weight distribution (Mw / Mn) of the base polymer is broad, low molecular weight and high molecular weight polymers may be present, which may result in the appearance of foreign matter on the pattern or deterioration of the pattern shape after exposure. As the pattern rules become finer, the influence of Mw and Mw / Mn tends to increase. Therefore, in order to obtain a resist material suitable for fine pattern dimensions, it is preferable that the Mw / Mn of the base polymer be narrowly dispersed, between 1.0 and 2.0, and particularly between 1.0 and 1.5.

[0144] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0145] [Acid Generator] The resist material of the present invention may contain an acid generator that generates a strong acid (hereinafter also referred to as an additive-type acid generator). Here, a strong acid means a compound having sufficient acidity to cause a deprotection reaction of acid-unstable groups of the base polymer in the case of a chemically amplified positive-type resist material, and a compound having sufficient acidity to cause a polarity change reaction or crosslinking reaction by an acid in the case of a chemically amplified negative-type resist material. By including such an acid generator, the aforementioned sulfonium salt A functions as a quencher, and the resist material of the present invention can function as a chemically amplified positive-type resist material or a chemically amplified negative-type resist material.

[0146] Examples of the acid-generating agent include compounds that generate acid in response to active light or radiation (photoacid generators). Any compound that generates acid upon irradiation with high-energy rays can be used as the photoacid generator, but those that generate sulfonic acid, imido acid, or methidoic acid are preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, etc. Specific examples of photoacid generators are those described in paragraphs

[0122] to

[0142] of Japanese Patent Publication No. 2008-111103.

[0147] Furthermore, sulfonium salts represented by the following formula (3-1) and iodonium salts represented by the following formula (3-2) can also be suitably used as photoacid generators. [ka]

[0148] In equations (3-1) and (3-2), R 101 ~R 105 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom.

[0149] R 101 ~R 105Examples of halogen atoms represented by this formula include fluorine, chlorine, bromine, and iodine atoms.

[0150] R 101 ~R 105 The hydrocarbyl group, represented by , having 1 to 20 carbon atoms, 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, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl; C3-C20 cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; C2-C20 alkenyl groups such as vinyl, propenyl, butenyl, and hexenyl; and ethynyl groups. Examples include alkynyl groups with 2 to 20 carbon atoms, such as propynyl and butynyl groups; cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 20 carbon atoms, such as cyclohexenyl and norbornenyl groups; aryl groups with 6 to 20 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, and tert-butylnaphthyl groups; aralkyl groups with 7 to 20 carbon atoms, such as benzyl and phenethyl groups; and groups obtained by combining these.

[0151] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a mercapto group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc.

[0152] Also, R 101 and R 102 These elements may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, the ring is preferably structured as shown below. [ka] (In the formula, the dashed line represents R 103 (This is a combination of the two.)

[0153] Examples of cations of the sulfonium salt represented by formula (3-1) include, but are not limited to, those listed below. [ka]

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157]

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[0158]

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[0159]

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[0160]

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[0161]

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[0162]

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[0163]

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[0164]

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[0165]

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[0166]

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[0167]

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[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] As the cation of the sulfonium salt represented by formula (3-1), the cation of the sulfonium salt represented by formula (1) can also be used.

[0178] The cations of the iodonium salt represented by formula (3-2) include, but are not limited to, those listed below. [ka]

[0179] [ka]

[0180] In equations (3-1) and (3-2), Xa - This is an anion selected from the following formulas (3A) to (3D). [ka]

[0181] In formula (3A), 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 (3A') described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0182] The anion represented by formula (3A) is preferably the one represented by formula (3A') below. [ka]

[0183] In formula (3A'), R HF R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 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 preferred to have 6 to 30 carbon atoms in order to obtain high resolution in fine pattern formation.

[0184] R fa1 The hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 38 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and eicosyl; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl Examples include cyclic saturated hydrocarbyl groups with 3 to 38 carbon atoms, such as C3, norbornylmethyl, tricyclodecyl, tetracyclododecyl, tetracyclododecylmethyl, and dicyclohexylmethyl; unsaturated aliphatic hydrocarbyl groups with 2 to 38 carbon atoms, such as allyl and 3-cyclohexenyl; aryl groups with 6 to 38 carbon atoms, such as phenyl, 1-naphthyl, and 2-naphthyl; aralkyl groups with 7 to 38 carbon atoms, such as benzyl and diphenylmethyl; and groups obtained by combining these.

[0185] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a 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. 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, and 3-oxocyclohexyl group.

[0186] For details on the synthesis of sulfonium salts containing the anion represented by formula (3A'), please refer to Japanese Patent Publication No. 2007-145797, Japanese Patent Publication No. 2008-106045, Japanese Patent Publication No. 2009-7327, Japanese Patent Publication No. 2009-258695, etc. 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.

[0187] Examples of anions represented by formula (3A) include those similar to those exemplified as anions represented by formula (1A) in Japanese Patent Publication No. 2018-197853.

[0188] In formula (3B), R fb1 and R fb2 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 (3A'). fa1Examples 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 This refers to the groups that bond to each other (-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.

[0189] In formula (3C), 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 (3A'). 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 This refers to the groups that bond to each other (-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.

[0190] In formula (3D), R fd This 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 given by formula ( 3 A') R in the middle fa1Examples of hydrocarbyl groups represented by the same formula as those exemplified above include those shown.

[0191] The synthesis of sulfonium salts containing the anion represented by formula (3D) is detailed in Japanese Patent Publication No. 2010-215608 and Japanese Patent Publication No. 2014-133723.

[0192] Examples of anions represented by formula (3D) include those similar to those exemplified as anions represented by formula (1D) in Japanese Patent Publication No. 2018-197853.

[0193] Furthermore, the photoacid generator containing the anion represented by formula (3D) does not have a fluorine atom at the α-position of the sulfo group, but has two trifluoromethyl groups at the β-position, which gives it sufficient acidity to cleave acid-unstable groups in the base polymer. Therefore, it can be used as a photoacid generator.

[0194] As a photoacid generator, one represented by the following formula (4) can also be suitably used. [ka]

[0195] In formula (4), R 201 and R 202 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain a halogen atom or a heteroatom. 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. In this case, the ring is R as described in the explanation of formula (3-1). 101 and R 102 Examples of rings that can be formed when these elements bond with each other, together with the sulfur atom to which they bond, are similar to those exemplified above.

[0196] R 201 and R 202 The hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 30 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-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 2,6 Examples include cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as decyl groups and adamantyl groups; aryl groups having 6 to 30 carbon atoms, such as phenyl groups, methylphenyl groups, ethylphenyl groups, n-propylphenyl groups, isopropylphenyl groups, n-butylphenyl groups, isobutylphenyl groups, sec-butylphenyl groups, tert-butylphenyl groups, naphthyl groups, methylnaphthyl groups, ethylnaphthyl groups, n-propylnaphthyl groups, isopropylnaphthyl groups, n-butylnaphthyl groups, isobutylnaphthyl groups, sec-butylnaphthyl groups, tert-butylnaphthyl groups, 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 a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, and as a result, it may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a 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.

[0197] R 203The hydrocarbylene group represented by 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 group, cyclohex Examples include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as xanediyl, norbornanediyl, and adamantanediyl groups; arylene groups having 6 to 30 carbon atoms, such as phenylene, methylphenylene, ethylphenylene, n-propylphenylene, isopropylphenylene, n-butylphenylene, isobutylphenylene, sec-butylphenylene, tert-butylphenylene, naphthylene, methylnaphthylene, ethylnaphthylene, n-propylnaphthylene, isopropylnaphthylene, n-butylnaphthylene, isobutylnaphthylene, sec-butylnaphthylene, and tert-butylnaphthylene; and groups obtained by combining these. 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- groups 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, the material may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. The heteroatom is preferably an oxygen atom.

[0198] In formula (4), LA This 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 are also available.

[0199] In formula (4), 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.

[0200] In equation (4), d is an integer between 0 and 3.

[0201] As the photoacid generator represented by formula (4), the one represented by the following formula (4') is preferred. [ka]

[0202] In formula (4'), L A The same as above. R HF 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 each 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 (3A'). fa1 Examples of hydrocarbyl groups represented by the formula shown are similar to those exemplified. x and y are each independent integers from 0 to 5, and z is an integer from 0 to 4.

[0203] Examples of photoacid generators represented by formula (4) include those similar to those exemplified as photoacid generators represented by formula (2) in Japanese Patent Publication No. 2017-26980.

[0204] Among the photoacid generators, those containing an anion represented by formula (3A') or (3D) are particularly preferred because they exhibit low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (4') are particularly preferred because they exhibit extremely low acid diffusion.

[0205] As the photoacid generator, a sulfonium salt or iodonium salt containing an anion having an aromatic ring substituted with an iodine or bromine atom can also be used. Examples of such salts are those represented by the following formulas (5-1) or (5-2). [ka]

[0206] In equations (5-1) and (5-2), p' is an integer satisfying 1 ≤ p' ≤ 3. q' and r' are integers satisfying 1 ≤ q' ≤ 5, 0 ≤ r' ≤ 3, and 1 ≤ q' + r' ≤ 5. q' is preferably an integer satisfying 1 ≤ q' ≤ 3, and more preferably 2 or 3. r' is preferably an integer satisfying 0 ≤ r' ≤ 2.

[0207] In equations (5-1) and (5-2), X BI p' and / or q' are iodine atoms or bromine atoms, and when p' and / or q' are 2 or more, they may be the same or different from each other.

[0208] In equations (5-1) and (5-2), L 1 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.

[0209] In equations (5-1) and (5-2), L 2When p' is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms, and when p' is 2 or 3, it is a (p'+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.

[0210] In equations (5-1) and (5-2), R 401 This may include 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 contain a C1-C20 hydrocarbyl group, a C1-C20 hydrocarbyloxy group, a C2-C20 hydrocarbylcarbonyl group, a C2-C20 hydrocarbyloxycarbonyl group, a C2-C20 hydrocarbylcarbonyloxy group, or a C1-C20 hydrocarbylsulfonyloxy group, or -N(R 401A )(R 401B ), -N(R 401C )-C(=O)-R 401D Or -N(R 401C )-C(=O)-OR 401D That is. R 401A and R 401B Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 401C 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. 401DThis is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyl group and hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. When p' and / or r' is 2 or more, each R 401 They may be the same or different from one another.

[0211] Of these, R 401 Examples include hydroxyl groups, -N(R 401C )-C(=O)-R 401D , -N(R 401C )-C(=O)-OR 401D Fluorine atoms, chlorine atoms, bromine atoms, methyl groups, methoxy groups, etc. are preferred.

[0212] In equations (5-1) and (5-2), Rf 1 ~Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group. Also, Rf 1 and Rf 2 These may combine to form a carbonyl group. In particular, Rf 3 and Rf 4 It is preferable that both are fluorine atoms.

[0213] In equations (5-1) and (5-2), R 402 ~R 406 Each of these is a hydrocarbyl group having 1 to 20 carbon atoms, which may independently contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. For example, in the explanation of formulas (3-1) and (3-2), R101 ~R 105 Examples of hydrocarbyl groups represented by the above are similar to those exemplified. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxyl group, carboxyl group, halogen atom, cyano group, nitro group, mercapto group, sultone ring, sulfo group, or sulfonium salt-containing group, and some of the -CH2- of the hydrocarbyl group may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond, or sulfonic acid ester bond. In addition, R 402 and R 403 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 R as described in the explanation of formula (3-1). 101 and R 102 Examples of rings that can be formed when these elements bond with each other, together with the sulfur atom to which they bond, are similar to those exemplified above.

[0214] Examples of cations for the sulfonium salt represented by formula (5-1) are the same as those exemplified for the sulfonium salt represented by formula (3-1). Similarly, examples of cations for the iodonium salt represented by formula (5-2) are the same as those exemplified for the iodonium salt represented by formula (3-2).

[0215] The anions of the onium salt represented by formula (5-1) or (5-2) include, but are not limited to, those listed below. Note that in the following formulas, X BI This is the same as described above. [ka]

[0216] [ka]

[0217] [ka]

[0218]

change

[0219]

change

[0220]

change

[0221]

change

[0222]

change

[0223]

change

[0224]

change

[0225]

change

[0226]

change

[0227]

change

[0228]

change

[0229]

change

[0230]

change

[0231]

change

[0232]

change

[0233]

change

[0234]

change

[0235]

change

[0236]

change

[0237]

change

[0238] When the resist material of the present invention contains an additive-type acid generator, its content is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The resist material of the present invention can function as a chemically amplified resist material by the base polymer containing any of the repeating units f1 to f3 and / or by containing an additive-type acid generator.

[0239] [Organic solvents] The resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the components described above and the components described later. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol Examples include ethers such as monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; and lactones such as γ-butyrolactone.

[0240] In the resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvent may be used alone or as a mixture of two or more types.

[0241] [Other ingredients] In addition to the components described above, the resist material of the present invention may also contain surfactants, dissolution inhibitors, crosslinking agents, quenchers other than sulfonium salt A (hereinafter referred to as "other quenchers"), water-repellency enhancers, acetylene alcohols, and the like.

[0242] Examples of the surfactants mentioned above include those described in paragraphs

[0165] to

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

[0243] When the resist material of the present invention is of the positive type, by incorporating a dissolution inhibitor, the difference in dissolution rate between the exposed and unexposed areas can be further increased, thereby further improving the resolution. Examples of the dissolution inhibitor include compounds in which the hydrogen atoms of the phenolic hydroxyl groups of a compound having a molecular weight of preferably 100 to 1000, more preferably 150 to 800 and containing two or more phenolic hydroxyl groups in the molecule are substituted with an acid-unstable group in a proportion of 0 to 100 mol% overall, or compounds in which the hydrogen atoms of the carboxyl group of a compound containing a carboxyl group in the molecule are substituted with an acid-unstable group in an average proportion of 50 to 100 mol overall. Specifically, examples include compounds in which the hydrogen atoms of the hydroxyl group or carboxyl group of bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid are substituted with an acid-unstable group, as described in paragraphs

[0155] to

[0178] of Japanese Patent Application Publication No. 2008-122932.

[0244] When the resist material of the present invention is of the positive type and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, and more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more types.

[0245] On the other hand, if the resist material of the present invention is negative type, a negative type pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluryl compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds such as alkenyloxy groups, which are substituted with at least one group selected from methylol groups, alkoxymethyl groups, and acyloxymethyl groups. These may be used as additives or introduced as pendant groups in the polymer side chains. Compounds containing hydroxyl groups can also be used as crosslinking agents.

[0246] Examples of the epoxy compound include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0247] Examples of the melamine compounds include hexamethylmelamine, hexamethoxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are methoxymethylated or mixtures thereof, hexamethoxyethylmelamine, hexaacyloxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are acyloxymethylated or mixtures thereof.

[0248] Examples of the guanamine compounds include tetramethylolguanamine, tetramethoxymethylguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated or mixtures thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, compounds in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated or mixtures thereof.

[0249] Examples of glycoluryl compounds include tetramethylol glycoluryl, tetramethoxy glycoluryl, tetramethoxymethyl glycoluryl, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are methoxymethylated or mixtures thereof, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are acyloxymethylated or mixtures thereof. Examples of urea compounds include tetramethylolurea, tetramethoxymethylurea, compounds in which 1 to 4 methylol groups of tetramethylolurea are methoxymethylated or mixtures thereof, tetramethoxyethylurea, and the like.

[0250] Examples of the isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0251] Examples of the aforementioned azide compounds include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0252] Examples of compounds containing the aforementioned alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0253] When the resist material of the present invention is of the negative type and contains the crosslinking agent, the content is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The crosslinking agent may be used alone or in combination of two or more types.

[0254] Examples of other quenchers include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, or tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, carbamates, etc. Particularly preferred are primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103, especially amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent Publication No. 3790649. By adding such basic compounds, for example, the diffusion rate of acid in the resist film can be further suppressed or its shape corrected.

[0255] Other quenchers include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids and carboxylic acids whose α-position is not fluorinated, as described in Japanese Patent Publication No. 2008-158339. Sulfonic acids, imido acids, or methidic acids with α-position fluorinated are necessary for deprotecting the acid-unstable group of carboxylic acid esters, but salt exchange with onium salts whose α-position is not fluorinated releases sulfonic acids or carboxylic acids whose α-position is not fluorinated. Since sulfonic acids and carboxylic acids whose α-position is not fluorinated do not undergo deprotection reactions, they function as quenchers.

[0256] Other quenchers include the polymer-type quencher described in Japanese Patent Publication No. 2008-239918. This enhances the rectangularity of the resist pattern by oriented on the surface of the resist film. Polymer-type quenchers also have the effect of preventing film thinning of the pattern and rounding of the pattern top when a protective film for immersion lithography is applied.

[0257] If the resist material of the present invention contains other quenchers, their content is preferably 0 to 5 parts by mass, and more preferably 0 to 4 parts by mass, per 100 parts by mass of the base polymer. The other quenchers may be used alone or in combination of two or more.

[0258] The water-repellent enhancer improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred water-repellent enhancers include polymers containing alkyl fluoride, polymers containing 1,1,1,3,3,3-hexafluoro-2-propanol residues of a specific structure, and those exemplified in Japanese Patent Publication No. 2007-297590 and Japanese Patent Publication No. 2008-111103 are more preferred. The water-repellent enhancer needs to be soluble in an alkaline developer or an organic solvent developer. The aforementioned water-repellent enhancer having a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue exhibits good solubility in the developer. As a water-repellent enhancer, polymers containing repeating units including amino groups or amine salts are highly effective in preventing acid evaporation in the PEB and thus preventing poor hole pattern opening after development. When the resist material of the present invention contains the water-repellency improving agent, its content is preferably 0 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The water-repellency improving agent may be used alone or in combination of two or more types.

[0259] Examples of the aforementioned acetylene alcohols include those described in paragraphs

[0179] to

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

[0260] [Pattern formation method] When the resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method may include a step of forming a resist film on a substrate using the resist material described above, a step of exposing the resist film with high-energy rays, and a step of developing the exposed resist film using a developer.

[0261] First, the resist material of the present invention is applied to a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, or doctor coating, so that the coating film thickness is 0.01 to 2 μm. This is then pre-baked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0262] Next, the resist film is exposed using high-energy rays. Examples of high-energy rays include ultraviolet rays, far-ultraviolet rays, EB rays, EUV rays with wavelengths of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When using ultraviolet rays, far-ultraviolet rays, EUV rays, X-rays, soft X-rays, excimer laser light, gamma rays, or synchrotron radiation as the high-energy rays, the exposure amount is preferably 1 to 200 mJ / cm², either directly or using a mask to form the desired pattern. 2 To the extent, more preferably 10 to 100 mJ / cm² 2 Irradiate to the extent of [a certain degree]. When using EB as the high-energy beam, the exposure dose is preferably 0.1 to 300 μC / cm². 2 To a degree, more preferably 0.5 to 200 μC / cm² 2 The pattern is drawn either directly or using a mask to form the desired pattern. The resist material of the present invention is particularly suitable for fine patterning using high-energy rays, including KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, gamma rays, and synchrotron radiation, and is especially suitable for fine patterning using EB or EUV.

[0263] After exposure, PEB may be performed on a hot plate or in an oven, preferably at 30-150°C for 10 seconds to 30 minutes, more preferably at 50-130°C for 30 seconds to 20 minutes, or it may not be performed.

[0264] After exposure or PEB, the exposed resist film is developed using a developer solution containing 0.1 to 10% by mass, preferably 2 to 5% by mass, of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by conventional methods such as the dip method, puddle method, or spray method, thereby forming the desired pattern. In the case of positive-type resist materials, the areas irradiated with light dissolve in the developer solution, while the unexposed areas do not dissolve, forming the desired positive-type pattern on the substrate. In the case of negative-type resist materials, the opposite is true: the areas irradiated with light become insoluble in the developer solution, while the unexposed areas dissolve.

[0265] Negative patterns can also be obtained by developing with organic solvents using positive-type resist materials containing a base polymer with acid-unstable groups. The developers used in this process include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotate, ethyl crotate, Examples include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenyl acetate, and 2-phenylethyl acetate. These organic solvents may be used individually or in mixtures of two or more.

[0266] At the end of development, rinsing is performed. A solvent that mixes with the developer but does not dissolve the resist film is preferred as the rinsing solution. Preferred solvents include C3-C10 alcohols, C8-C12 ether compounds, C6-C12 alkanes, alkenes, alkynes, and aromatic solvents.

[0267] The C3-C10 alcohols include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, Examples include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

[0268] Examples of the ether compounds having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0269] Examples of C6-C12 alkanes include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Examples of C6-C12 alkenes include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Examples of C6-C12 alkynes include hexine, heptine, and octine.

[0270] Examples of the aforementioned aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0271] Rinsing can reduce the occurrence of resist pattern deformation and defects. However, rinsing is not always necessary, and omitting it can reduce the amount of solvent used.

[0272] The developed hole patterns and trench patterns can also be shrunk using thermal flow, RELACS, or DSA techniques. A shrinking agent is applied to the hole pattern, and crosslinking of the shrinking agent occurs on the surface of the resist film due to the diffusion of an acid catalyst from the resist film during baking, causing the shrinking agent to adhere to the side walls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds, during which excess shrinking agent is removed and the hole pattern is reduced in size. [Examples]

[0273] 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.

[0274] [Example 1-1] Synthesis of Quencher Q-1 (1) Synthesis of intermediate In-1 [ka]

[0275] Under a nitrogen atmosphere, 20 mL of a solution of 2-bromobenzothiophene (50 g) diluted with THF (320 mL) was added to magnesium (4.85 g), and the temperature was raised to 60°C. After cooling the reaction solution to 40°C, the remaining 2-bromobenzothiophene THF solution was added while maintaining a temperature of 40-50°C, and the mixture was stirred for 18 hours to prepare a Grignard solution. Subsequently, the prepared Grignard solution was added dropwise to a THF solution of dry ice (300 mL), and the mixture was stirred for 7 hours. During this time, the amount of dry ice was adjusted as needed to ensure that an excess amount of dry ice was always present. After the reaction was complete, the reaction was stopped with 20% hydrochloric acid (200 g), ethyl acetate (400 g) was added as the extraction solvent for the target product, and the target product was washed four times with pure water (100 g). The organic layer was separated, and after the solvent was removed by distillation, crystals precipitated. Recrystallization was performed by adding toluene (300 mL), and then drying under reduced pressure to obtain 19.8 g of the intermediate In-1 as a white solid (yield: 46%).

[0276] (2) Synthesis of intermediate In-2 [ka]

[0277] Intermediate In-1 (58.5 g) was dissolved in methanol (350 g), and then sulfuric acid (6.3 g) was added. The mixture was heated under reflux at 80°C for 24 hours while monitoring by NMR. After the reaction was complete, the mixed solution was allowed to return to room temperature, and then the pH was neutralized (pH 7) using triethylamine while cooling in an ice bath, and the solvent was removed by distillation. Subsequently, using a mixed solvent of toluene:ethyl acetate = 2:1 (800 g), liquid-liquid extraction was performed twice with pure water (100 g), once with saturated sodium bicarbonate aqueous solution (100 g), and five times with pure water (100 g) to confirm neutrality, after which the organic layer was separated. After removing the extraction solvent under reduced pressure, recrystallization was performed using cooled hexane (300 g), and drying under reduced pressure yielded 48.8 g of intermediate In-2 as white crystals (yield: 79%).

[0278] (3) Synthesis of intermediate In-3 [ka]

[0279] Intermediate In-2 (10g), copper acetate (0.26g), starting material M-1 (19.6g), and anisole (50g) were mixed, and the reaction system was heated to 95°C and stirred for 2 hours. After the reaction was complete, diisopropyl ether (150g) was added, causing white crystals to precipitate, and the mixture was stirred for an additional hour. After filtering off the white solid, it was dissolved in dichloromethane, activated carbon was added, and the mixture was stirred for a further 2 hours. After removing the activated carbon by filtration, the solvent was removed under reduced pressure, and recrystallization with methyl isobutyl ketone (50g) and vacuum drying were performed to obtain 15.5g of intermediate In-3 as white crystals (yield: 80%).

[0280] (4) Synthesis of intermediate In-4 [ka]

[0281] Intermediate In-3 (13 g), Amberlite (40 g), and methanol (100 g) were mixed and stirred at room temperature for 3 hours. After the reaction was complete, Amberlite was removed by filtration and the solvent was removed by distillation. Decantation was performed several times with hexane, followed by recrystallization and drying under reduced pressure to obtain 8.9 g of In-4 as a white solid (90%).

[0282] (5) Example of Quencher Q-1 Synthesis [ka]

[0283] Intermediate In-4 (16.1g), starting material M-2 (12.5g), dichloromethane (165g), and pure water (50g) were mixed and stirred at room temperature for 1 hour. After the reaction was complete, the organic layer was separated and washed four times with pure water (50g) to confirm that the pH was neutral. After removing the solvent under reduced pressure, recrystallization was performed using diisopropyl ether (60g), and the filtered solid was dried under reduced pressure to obtain 21.7g of the target quencher Q-1 as white crystals (yield: 92%).

[0284] [Examples 1-2 to 1-22] Quencher Q-2 to Q-2 2 synthesis Quenchers Q-2 to Q-22 were synthesized using the same method as in Example 1-1. The structures of quenchers Q-1 to Q-22 are shown below. [ka]

[0285] [ka]

[0286] [ka]

[0287] [ka]

[0288] [Synthesis Example] Synthesis of base polymers (P-1 to P-5) Each monomer was combined and copolymerized in THF, a solvent. The resulting reaction solution was placed in methanol, and the precipitated solid was washed with hexane, then isolated and dried to obtain base 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: THF, standard: polystyrene). [ka]

[0289] [ka]

[0290] [Examples 2-1 to 2-26, Comparative Examples 1-1 to 1-3] Preparation and Evaluation of Resist Materials (1) Preparation of resist material The resist materials were prepared by dissolving each component in the compositions shown in Tables 1 and 2, and then filtering the solutions through a 0.2 μm filter. The resist materials of Examples 1-25 and Comparative Examples 1 and 2 were positive type, while the resist materials of Example 26 and Comparative Example 3 were negative type.

[0291] In Tables 1 and 2, the components are as follows: • Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol) EL (Ethyl Lactate)

[0292] • Acid generators: PAG-1 to PAG-4 [ka]

[0293] • Blend Quencher: bQ-1, bQ-2 [ka]

[0294] • Comparative quenchers: cQ-1, cQ-2 [ka]

[0295] (2) EUV lithography evaluation Each resist material shown in Tables 1 and 2 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% 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 60 nm was then fabricated by pre-baking at 100°C for 60 seconds using a hot plate. Next, the resist film was exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, wafer-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 1 and 2 for 60 seconds, and development was performed with a 2.38% by mass TMAH aqueous solution for 30 seconds to obtain hole patterns with dimensions of 22 nm in Examples 1 to 25 and Comparative Examples 1 and 2, and dot patterns with dimensions of 22 nm in Example 26 and Comparative Example 3. Using a Hitachi High-Technologies Corporation length-measuring SEM (CG6300), the exposure amount at which a hole or dot dimension of 22 nm was formed was measured and defined as the sensitivity. The dimensions of 50 holes or dots at this point were also measured, and the CDU was defined as three times the standard deviation (σ) calculated from these results (3σ). The results are shown in Tables 1 and 2.

[0296] [Table 1]

[0297] [Table 2]

[0298] The results shown in Tables 1 and 2 indicate that the resist material containing the sulfonium salt of the present invention exhibits high sensitivity and improved CDU (Critical Duty Unit).

Claims

1. A sulfonium salt represented by the following formula (1). 【Chemistry 1】 (In the formula, p, q, and r are each independent integers between 0 and 3, and s is either 1 or 2.) R 1 and R 2 These are, independently, a halogen atom, a trifluoromethyl group, a trifluoromethoxy group, a trifluoromethylthio group, a nitro group, a cyano group, and -C(=O)-R. 4 , -O-C(=O)-R 5 OR -OR 5 That is the case. R 3 This includes halogen atoms, trifluoromethyl groups, trifluoromethoxy groups, trifluoromethylthio groups, nitro groups, cyano groups, and -O-C(=O)-R 5 OR -OR 5 That is the case. R 4 is a hydrocarbyl group having 1 to 10 carbon atoms, a hydrocarbyloxy group having 1 to 10 carbon atoms or -O-R 4A wherein the hydrocarbyl group and the hydrocarbyloxy group may be substituted with a fluorine atom or a hydroxy group. R 4A is an acid-labile group. R 5 This is a hydrocarbyl group having 1 to 10 carbon atoms. X 1 R is a single bond, an ether group, a carbonyl group, an -N(R)-, a sulfide bond, or a sulfonyl group. R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. Xq - This is a carboxylic acid anion represented by the following formula (2), having a hydroxyl group bonded to a carbon atom other than the carbon atom of the aromatic ring, and a fluorine atom or a trifluoromethyl group at the α or β position. 【Chemistry 2】 (In the formula, n is either 0 or 1.) R6 to R9 are independently a hydrogen atom, a fluorine atom, and a trifluoromethyl group, respectively. When n is 0, at least one of R6 and R7 is either a fluorine atom or a trifluoromethyl group, and when n is 1, at least one of R6 to R9 is either a fluorine atom or a trifluoromethyl group. R10 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms. However, the carbon atoms in R10 to which the -OH group is bonded are not carbon atoms of the aromatic ring.

2. The sulfonium salt according to claim 1, wherein R 10 is a single bond or a group represented by the following formula (2)-1. 【Transformation 3】 (In the formula, * represents the bonds between R6 and R7 and the carbon atom to which they are bonded when n is 0, and the bonds between R8 and R9 and the carbon atom to which they are bonded when n is 1. ** represents the bonds with -OH.) R10A and R10B are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. Alternatively, R10A and R10B may bond to each other to form a ring with the carbon atoms to which they are bonded. R 10C is a single bond or a hydrocarbylene group having 1 to 10 carbon atoms. However, the carbon atoms in R 10C to which the -OH group is bonded are not carbon atoms of the aromatic ring. The number of carbon atoms in the group represented by formula (2)-1 is 20 or less.

3. n is 0, R 10 It is a single bond, R 6 and R 7 The sulfonium salt according to claim 1, wherein is a trifluoromethyl group.

4. A resist material comprising a quencher containing a sulfonium salt according to any one of claims 1 to 3.

5. Furthermore, the resist material according to claim 4, further comprising a base polymer.

6. The resist material according to claim 5, wherein the base polymer includes a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2). 【Transformation 3】 (In the formula, R A Each of these is independently either a hydrogen atom or a methyl group. Y 1 This is a linking group having 1 to 12 carbon atoms, containing at least one selected from a single bond, a phenylene group or a naphthylene group, or an ester bond and a lactone ring. Y 2 These are single bonds or ester bonds. Y 3 These are single bonds, ether bonds, or ester bonds. R 11 and R 12 These are, independently, acid-unstable groups. R 13 This is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 14 This is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and some of its carbon atoms may be substituted with ether bonds or ester bonds. a is either 1 or 2. b is an integer between 0 and 4, where 1 ≤ a + b ≤ 5.

7. The resist material according to claim 6, which is a chemically amplified positive resist material.

8. The resist material according to claim 5, wherein the base polymer does not contain acid-unstable groups.

9. The resist material according to claim 8, which is a chemically amplified negative resist material.

10. The resist material according to claim 5, wherein the base polymer comprises at least one selected from repeating units represented by the following formulas (f1) to (f3). 【Chemistry 4】 (In the formula, R A Each of these is independently either a hydrogen atom or a methyl group. Z 1 This includes single bonds, aliphatic hydrocarbylene groups having 1 to 6 carbon atoms, phenylene groups, naphthylene groups, or groups having 7 to 18 carbon atoms obtained by combining these, or -O-Z. 11 -, -C(=O)-O-Z 11 - or -C(=O)-NH-Z 11 - is Z 11 This is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z 2 These are single bonds or ester bonds. Z 3 This is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -O-C(=O)-. Z 31 This is an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, a urethane bond, a nitro group, a cyano group, a fluorine atom, an iodine atom, or a bromine atom. Z 4 This is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and -O-Z. 51 -, -C(=O)-O-Z 51 - or -C(=O)-NH-Z 51 - is Z 51 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, a halogen atom, or a hydroxyl group. R 21 ~R 28 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. 23 and R 24 and or R 26 and R 27 These atoms may bond to each other, forming a ring with the sulfur atom to which they are bonded. M - (It is a non-nucleophilic counterion.)

11. Furthermore, the resist material according to claim 4 further includes an acid generator that generates a strong acid.

12. The resist material according to claim 11, wherein the acid generating agent generates sulfonic acid, imido acid, or methido acid.

13. Furthermore, the resist material according to claim 4, further comprising an organic solvent.

14. Furthermore, the resist material according to claim 4, further comprising a surfactant.

15. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist material described in claim 4; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

16. The pattern formation method according to claim 15, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

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