Novel sulfonium salts, resist compositions, and patterning methods

Abstract

The present invention provides a sulfonium salt used in a resist composition that exhibits excellent solvent solubility, high sensitivity and contrast, and superior lithography performance such as exposure margin and LWR; a resist composition containing the sulfonium salt as a photoacid generator; and a pattern formation method using the resist composition. [Solution] A sulfonium salt represented by the following formula (1). TIFF2026094296000179.tif35127 (In the formula, p is an integer from 1 to 3, R 11 is a hydrocarbyl group, R f is an F atom, an F-containing alkyl group, an alkoxy group, or a sulfide group, q is an integer from 1 to 4, R ALU is an acid-unstable group, r is an integer from 1 to 4, R 12 represents a hydrocarbyl group, s is an integer from 0 to 4, and t is an integer from 0 to 2. - (This represents a non-nucleophilic counterion that does not contain polymerizable groups.)

Description

[Technical Field]

[0001] The present invention relates to a novel sulfonium salt compound, a resist composition containing the sulfonium salt compound, and a patterning method. [Background technology]

[0002] In recent years, with the increasing integration and speed of LSIs, there has been a growing demand for miniaturization of pattern rules. As a result, far ultraviolet lithography and extreme ultraviolet (EUV) lithography are considered promising next-generation microfabrication technologies. Among these, photolithography using ArF excimer laser light is an indispensable technology for ultra-fine processing of 0.13 μm or less.

[0003] ArF lithography began to be used partially for the fabrication of 130nm node devices and became the main lithography technology for 90nm node devices. Initially, 157nm lithography using an F2 laser was considered promising as the next 45nm node lithography technology, but development delays due to various problems were pointed out. As a result, ArF immersion lithography, which can achieve high resolution by inserting a liquid with a refractive index higher than air, such as water, ethylene glycol, or glycerin, between the projection lens and the wafer, and designing the numerical aperture (NA) of the projection lens to be 1.0 or higher, has rapidly emerged (Non-Patent Literature 1) and is now in the practical application stage. This immersion lithography requires a resist composition that is not easily eluted by water.

[0004] In ArF lithography, highly sensitive resist compositions that can achieve sufficient resolution with low exposure are required to prevent degradation of precise and expensive optical materials. The most common way to achieve this is to select components that are highly transparent at a wavelength of 193 nm. For example, polyacrylic acid and its derivatives, norbornene-maleic anhydride alternating polymers, polynorbornene, ring-opening metathesis polymers, and ring-opening metathesis polymer hydrogenated polymers have been proposed as base polymers, and some success has been achieved in improving the transparency of the resin itself.

[0005] In recent years, negative-tone resists developed using organic solvents have gained attention alongside positive-tone resists developed using alkaline aqueous solutions. To resolve extremely fine hole patterns that cannot be achieved with positive tones, negative patterns are formed by using a high-resolution positive-type resist composition and developing it with an organic solvent. Furthermore, research is underway to obtain twice the resolution by combining two development processes: alkaline aqueous solution development and organic solvent development. Conventional positive-type ArF resist compositions can be used as ArF resist compositions for negative-tone development with organic solvents, and pattern formation methods using such compositions are described in Patent Documents 1 to 3.

[0006] To adapt to the rapid miniaturization of recent years, the development of resist compositions is progressing daily, along with process technologies. Various photoacid generators have been investigated, and sulfonium salts consisting of triphenylsulfonium cations and perfluoroalkanesulfonic acid anions are commonly used. However, the generated acid, perfluoroalkanesulfonic acid, particularly perfluorooctanesulfonic acid (PFOS), is difficult to decompose, bioaccumulates, and poses toxicity concerns, making its application to resist compositions difficult. Currently, photoacid generators that produce perfluorobutanesulfonic acid are used. However, when this is used in resist compositions, the diffusion of the generated acid is large, making it difficult to achieve high resolution. To address this problem, various partially fluorine-substituted alkanesulfonic acids and their salts have been developed. For example, Patent Document 1 describes, as prior art, a photoacid generator that generates α,α-difluoroalkanesulfonic acid upon exposure, specifically di(4-tert-butylphenyl)iodonium 1,1-difluoro-2-(1-naphthyl)ethanesulfonate and a photoacid generator that generates α,α,β,β-tetrafluoroalkanesulfonic acid. However, although the fluorine substitution rate is reduced in all of these, they do not have decomposable substituents such as ester structures, making them insufficient from the standpoint of environmental safety due to their easy decomposition. Furthermore, there are limitations in molecular design for changing the size of the alkanesulfonic acid, and the starting materials containing fluorine atoms are expensive.

[0007] Furthermore, with the reduction in circuit line width, the effect of contrast degradation due to acid diffusion in resist compositions has become even more serious. This is because the pattern dimensions approach the acid diffusion length, leading to a decrease in mask fidelity and deterioration of pattern rectangularity due to a larger dimensional deviation on the wafer (mask error factor (MEF)) relative to the dimensional deviation of the mask. Therefore, in order to fully obtain the benefits of shorter wavelength and higher NA of the light source, it is necessary to increase the dissolution contrast or suppress acid diffusion more than with conventional materials. As one solution, it is possible to reduce acid diffusion by lowering the bake temperature, and as a result improve the MEF, but this inevitably leads to lower sensitivity.

[0008] Introducing bulky substituents or polar groups into photoacid generators is effective in suppressing acid diffusion. Patent document 4 describes a photoacid generator having 2-acyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonic acid, which has excellent solubility and stability in resist solvents and allows for a wide range of molecular designs. In particular, photoacid generators having 2-(1-adamantyloxy)-1,1,3,3,3-pentafluoropropane-1-sulfonic acid with bulky substituents exhibit low acid diffusion. Patent documents 5 to 7 also describe photoacid generators with condensed ring lactones, sultones, or thiolactones introduced as polar groups. Although some performance improvement has been confirmed due to the acid diffusion suppression effect of introducing polar groups, it is still insufficient for advanced control of acid diffusion, and the lithography performance is not satisfactory when considering MEF, pattern shape, sensitivity, etc.

[0009] Introducing polar groups into the anion of a photoacid generator is effective in suppressing acid diffusion, but it is disadvantageous from the viewpoint of solvent solubility. Patent documents 8 and 9 describe attempts to improve solvent solubility by introducing alicyclic groups into the cation portion of the photoacid generator, specifically introducing cyclohexane rings and adamantane rings. Although solubility is improved by introducing such alicyclic groups, a certain number of carbon atoms is required to ensure solubility, and as a result the molecular structure of the photoacid generator becomes bulky, which degrades lithography performance such as line width roughness (LWR) and dimensional uniformity (CDU) when forming fine patterns.

[0010] Patent documents 10 and 11 describe methods for introducing acid-unstable groups into the anions or cations of photoacid generators in order to improve dissolution contrast. Many of these have a structure in which a carboxylic acid is protected by an acid-unstable group. Although the deprotection reaction of the protecting group by acid proceeds before and after exposure, the resulting polar group is a carboxyl group, which causes swelling in the developer during alkaline development and pattern collapse during fine pattern formation. In order to meet the demand for further miniaturization, the development of novel photoacid generators is important, and there is a need for photoacid generators that have well controlled acid diffusion, excellent solvent solubility, and are effective in suppressing pattern collapse. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2008-281974 [Patent Document 2] Japanese Patent Publication No. 2008-281975 [Patent Document 3] Patent No. 4554665 [Patent Document 4] Japanese Patent Publication No. 2007-145797 [Patent Document 5] Patent No. 5061484 [Patent Document 6] Japanese Patent Publication No. 2016-147879 [Patent Document 7] Japanese Patent Publication No. 2015-63472 [Patent Document 8] Patent No. 5573098 [Patent Document 9] Patent No. 6461919 [Patent Document 10] Patent No. 5544078 [Patent Document 11] Patent No. 5609569 [Non-patent literature]

[0012] [Non-Patent Document 1] Journal of photopolymer Science and Technology Vol.17,No.4,p.587-601(2004) [Overview of the project] [Problems that the invention aims to solve]

[0013] In response to the recent demand for high-resolution resist patterns, conventional resist compositions using sulfonium salt-type photoacid generators cannot adequately suppress acid diffusion, resulting in a degradation of lithography performance such as contrast, MEF, and line width roughness (LWR). Furthermore, during fine pattern formation, there is the problem of pattern collapse due to swelling.

[0014] The present invention has been made in view of the above circumstances, and aims to provide a sulfonium salt used in a resist composition that has excellent solvent solubility, high sensitivity and high contrast, and excellent lithography performance such as exposure margin (EL) and LWR, a resist composition containing the sulfonium salt as a photoacid generator, and a pattern formation method using the resist composition. [Means for solving the problem]

[0015] To solve the above problems, the present invention provides a sulfonium salt represented by the following formula (1). [ka] (In the formula, p is an integer from 1 to 3. R 11 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Furthermore, two of the three substituents bonded to the sulfonium cation may bond to each other, forming a ring with the sulfur atom to which they are bonded. f represents a fluorine atom, a fluorine-containing alkyl group with 1 to 6 carbon atoms, an alkoxy group, or a sulfide group. q represents an integer from 1 to 4, and if q ≥ 2, R f They may be the same or different from each other.ALU represents an acid-labile group formed together with an adjacent oxygen atom. r is an integer from 1 to 4. R 12 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. s is an integer from 0 to 4. t represents an integer from 0 to 2. When t = 0, q + r + s ≤ 5; when t = 1, q + r + s ≤ 7; when t = 2, q + r + s ≤ 9. R f and -O-R ALU are bonded to adjacent carbon atoms to each other. X - represents a non-nucleophilic counter ion that does not contain a polymerizable group. )

[0016] For such a sulfonium salt, by blending it into a resist composition, a resist composition excellent in solvent solubility, high sensitivity and high contrast, and excellent in lithography performance such as exposure margin (EL) and LWR can be provided.

[0017] In the present invention, in the above formula (1), it is preferable that R ALU is represented by the following formula (ALU-1) or (ALU-2).

Chemical formula

[0018] By incorporating such sulfonium salts into a resist composition, it is possible to obtain a resist composition with even better lithography performance.

[0019] In the above sulfonium salt, in formula (1), X - The non-nucleophilic counterion that does not contain polymerizable groups is preferably a sulfonate anion, an imidoate anion, or a methidoate anion.

[0020] In the above-mentioned sulfonium salt, such non-nucleophilic counterions can be suitably used.

[0021] Furthermore, the present invention provides a photoacid generator comprising the above-mentioned sulfonium salt.

[0022] The sulfonium salt of the present invention is suitable as a photoacid generator.

[0023] Furthermore, the present invention provides a resist composition containing the above-mentioned photoacid generator.

[0024] The resist composition of the present invention exhibits excellent solvent solubility, high sensitivity and contrast, and superior lithography performance such as exposure margin (EL) and LWR.

[0025] In this case, it is preferable to include a base resin having repeating units represented by the following formula (a1) or (a2). [ka] (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. AThis refers to a single bond, a phenylene group, a naphthylene group, or (main chain)-C(=O)-OZ A1 - and Z A1 This is a linear, branched, or cyclic alkanediyl group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. B The bond is either a single bond or (main chain)-C(=O)-O-. A and X B These are, independently, acid-unstable groups. B (where n is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. n is an integer from 0 to 4.)

[0026] Such base resins can be suitably used in the resist composition of the present invention.

[0027] The resist composition of the present invention preferably comprises a base resin further containing repeating units represented by the following formula (b1) or (b2). [ka] (In the formula, R A , Z B This is the same as above. Y A R is a polar group comprising a hydrogen atom, or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a sulfonic acid amide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic acid anhydride. b (m is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. m represents an integer from 1 to 4.)

[0028] As the base resin to be incorporated into the resist composition of the present invention, one containing such repeating units can be suitably used.

[0029] The resist composition of the present invention is further preferably characterized in that the base resin contains at least one repeating unit selected from the repeating units represented by the following formulas (c1) to (c4). [ka] (In the formula, R A This is the same as above. Z 1 This is a single bond or a phenylene group. 2 This is a single bond, *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or *-OZ 21 - is Z 21 This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 - is Z 31 This is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. 4 This refers to a single bond, a methylene group, or *-Z 41 -C(=O)-O- Z 41 This is a C1-C20 hydrocarbylene group which may contain heteroatoms, ether bonds, or ester bonds. 5 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-OZ. 51 -, *-C(=O)-N(H)-Z 51 -or *-OZ 51 - is Z 51 This is a phenylene group substituted with an aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, or trifluoromethyl group having 1 to 6 carbon atoms, and may also contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * represents a bond with a carbon atom in the main chain or a group on the main chain side. R21 and R 22 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Also, R 21 and R 22 These may bond with each other to form a ring with the sulfur atom to which they are bonded. 1 These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Rf 1 and Rf 2 Each of these is independently a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. However, all Rf 5 and Rf 6 They cannot become hydrogen atoms at the same time. - A is a non-nucleophilic counterion. + c is an onium cation. c is an integer between 0 and 3.

[0030] A base resin containing such repeating units can be more preferably used as the base resin to be incorporated into the resist composition of the present invention.

[0031] The resist composition of the present invention preferably further contains an organic solvent.

[0032] Such a resist composition offers excellent workability.

[0033] The resist composition of the present invention preferably further contains a compound represented by the following formula (5) or (6). [ka] (In the formula, R q1This refers to a monovalent hydrocarbon group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. q2 This is a monovalent hydrocarbon group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom. + (This is an onium cation.)

[0034] The resist composition of the present invention can control acid diffusion by including the above compound as a quencher.

[0035] The resist composition of the present invention preferably further contains other photoacid generators in addition to the above-mentioned photoacid generator.

[0036] Such a resist composition will result in good resolution.

[0037] The resist composition of the present invention preferably further contains an amine compound.

[0038] Amine compounds can act as quenchers, allowing for more favorable control of acid diffusion.

[0039] The resist composition of the present invention preferably further contains a surfactant that is insoluble or sparingly soluble in water and soluble in an alkaline developer, and / or a surfactant that is insoluble or sparingly soluble in both water and an alkaline developer.

[0040] Such surfactants are useful in ArF immersion lithography when a resist protective film is not used, because they have the function of reducing water penetration and leaching by orienting themselves on the surface of the resist film. This suppresses the elution of water-soluble components from the resist film and reduces damage to the exposure equipment. Furthermore, they are useful because they become solubilized during alkaline aqueous solution development after exposure and post-exposure baking (PEB), and are less likely to become foreign substances that cause defects.

[0041] Furthermore, the present invention provides a pattern formation method comprising the steps of: forming a resist film on a substrate using the above-mentioned resist composition; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.

[0042] With this pattern formation method, since the resist composition of the present invention is used, it is possible to form patterns with high sensitivity and high contrast, and excellent lithography performance such as exposure margin (EL) and LWR.

[0043] In this case, the high-energy beam is preferably KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0044] The pattern formation method of the present invention allows for the suitable use of such high-energy rays. [Effects of the Invention]

[0045] As described above, when pattern formation is performed using a resist composition containing the sulfonium salt of the present invention as a photoacid generator, it is possible to form a resist pattern with high contrast, good sensitivity, excellent lithography performance such as MEF and LWR, and suppressed pattern deformation. In particular, in photolithography using high-energy beams such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV, the chemically amplified resist composition containing the sulfonium salt of the present invention as a photoacid generator has excellent solvent solubility, high sensitivity and high contrast, and excellent lithography performance such as exposure margin (EL) and LWR. [Brief explanation of the drawing]

[0046] [Figure 1] This is the 1H-NMR spectrum of the compound obtained in Example I-1. [Figure 2] This is the 1H-NMR spectrum of the compound obtained in Example I-2. [Figure 3]This is the 1H-NMR spectrum of the compound obtained in Example I-3. [Figure 4] This is the 1H-NMR spectrum of the compound obtained in Example I-4. [Figure 5] This is the 1H-NMR spectrum of the compound obtained in Example I-5. [Modes for carrying out the invention]

[0047] As described above, there was a need to develop a photoacid generator that would allow for sufficient control of acid diffusion, exhibit excellent solvent solubility, have superior lithography performance such as LER, and be effective in suppressing pattern deformation.

[0048] As a result of diligent research to achieve the above objective, the present inventors discovered that sulfonium salts of a specific structure exhibit excellent solvent solubility, and that resist compositions such as chemically amplified resist compositions using these as photoacid generators exhibit high sensitivity and high contrast, excellent lithography performance such as EL and LWR, and are extremely effective in suppressing pattern collapse during fine pattern formation. This led to the present invention.

[0049] In other words, the present invention relates to a sulfonium salt represented by the following formula (1). [ka] (In the formula, p is an integer from 1 to 3. R 11 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Furthermore, two of the three substituents bonded to the sulfonium cation may bond to each other, forming a ring with the sulfur atom to which they are bonded. f represents a fluorine atom, a fluorine-containing alkyl group with 1 to 6 carbon atoms, an alkoxy group, or a sulfide group. q represents an integer from 1 to 4, and if q ≥ 2, R f They may be the same or different from each other. ALU R represents an acid-unstable group formed with adjacent oxygen atoms. r is an integer from 1 to 4. 12is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. s is an integer from 0 to 4. t represents an integer from 0 to 2. When t=0, q+r+s≦5; when t=1, q+r+s≦7; and when t=2, q+r+s≦9. R f and -OR ALU X is bonded to adjacent carbon atoms. - (This represents a non-nucleophilic counterion that does not contain polymerizable groups.)

[0050] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0051] [Sulfonium salt] The sulfonium salt of the present invention is represented by the following formula (1). [ka]

[0052] Below, the structure within the parentheses of equation (1) is Ar f It is also said that Ar f This structure is represented by the following equation (1-1), and equation (1) can also be expressed as shown in equation (1-2). [ka]

[0053] [R 11 ] 3-p S + Ar f p X - (1-2)

[0054] In equation (1), p is an integer between 1 and 3.

[0055] In formula (1), R 11is a hydrocarbyl group having 1 to 20 carbon atoms which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group; aryl groups having 2 to 20 carbon atoms such as phenyl group, naphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; groups obtained by combining these, and the like. Among these, an aryl group is preferred. Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, and part of -CH2- constituting the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, and as a result, it may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0056] When p = 1, aromatic ring Ar f and two Rs 11 Any two of them may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. When p = 2, two aromatic rings Ar f and one R 11 Any two of them may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. When p = 3, three aromatic rings Ar fAny two of these may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, examples of sulfonium cations include those represented by the following formula. [ka] (In the formula, the dashed lines represent the remaining bonds of the sulfonium cation.)

[0057] In formula (1), t is an integer between 0 and 2. When t is 0, it is a benzene ring; when t is 1, it is a naphthalene ring; and when t is 2, it is an anthracene ring. However, from the viewpoint of solvent solubility, a benzene ring when t is 0 is preferred.

[0058] In formula (1), R f The terms represent a fluorine atom, a fluorine atom-containing alkyl group having 1 to 6 carbon atoms, an alkoxy group, or a sulfide group. Examples of the fluorine atom-containing alkyl group having 1 to 6 carbon atoms include fluoromethyl group, difluoromethyl group, trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, pentafluoropropyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group, and nonafluorobutyl group. Examples of the fluorine atom-containing alkoxy group having 1 to 6 carbon atoms include fluoromethoxy group, difluoromethoxy group, trifluoromethoxy group, 2,2,2-trifluoroethoxy group, pentafluoroethoxy group, pentafluoropropoxy group, 1,1,1,3,3,3-hexafluoro-2-propoxy group, and nonafluorobutoxy group. Examples of the fluorine atom-containing sulfide groups having 1 to 6 carbon atoms include fluorothiomethoxy group, difluorothiomethoxy group, trifluorothiomethoxy group, 2,2,2-trifluorothioethoxy group, pentafluorothioethoxy group, pentafluorothiopropoxy group, 1,1,1,3,3,3-hexafluoro-2-thiopropoxy group, nonafluorothiobutoxy group, etc. Of these, R f Preferably, it is a fluorine atom or a fluorine atom-containing alkoxy group having 1 to 6 carbon atoms, and more preferably a fluorine atom or a trifluoromethoxy group.

[0059] In formula (1), q represents an integer from 1 to 4. When q ≥ 2, R f may be the same or different from each other. From the perspective of ease of raw material procurement, q is preferably 1 or 2.

[0060] In formula (1), R 12 is a hydrocarbyl group having 1 to 20 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 include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group; aryl groups having 2 to 20 carbon atoms such as phenyl group, naphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; groups obtained by combining these, and the like. Among these, an aryl group is preferable. Further, 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, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH2- constituting the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. As a result, it may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0061] In formula (1), s represents an integer from 0 to 4, and is preferably 0 or 1.

[0062] In formula (1), R ALUThe symbol represents an acid-unstable group formed together with an adjacent oxygen atom. Here, an acid-unstable group refers to a group in which an acidic functional group, such as a phenolic hydroxyl group or a carboxyl group, is replaced with one or more functional groups that can decompose in the presence of an acid, and is not particularly limited as long as it decomposes in the presence of an acid to release an alkali-soluble functional group. In equation (1), r represents an integer from 1 to 4, and when r ≥ 2, R ALU They may be the same or different from one another. When t=0, the aromatic ring is a benzene ring, and q+r+s≦5. When t=1, the aromatic ring is a naphthalene ring, and q+r+s≦7. When t=2, the aromatic ring is an anthracene ring, and q+r+s≦9. f and -OR ALU They are bonded to adjacent carbon atoms. If q or r is 2 or more, at least one pair of R f and -OR ALU It is sufficient if the R atoms are bonded to adjacent carbon atoms, but all R atoms f and -OR ALU It is preferable that the atoms are bonded to adjacent carbon atoms. As will be described later, f and -OR ALU Sulfonium salts having a structure in which these groups are bonded to adjacent carbon atoms can provide a resist composition that, due to the synergistic effect of these groups, exhibits high dissolution contrast, excellent LWR for line patterns and CDU for hole patterns, and enables pattern formation that is resistant to pattern collapse.

[0063] acid labile group R ALU Specifically, a structure represented by the following formula (ALU-1) or (ALU-2) is preferred. [ka]

[0064] In formula (ALU-1), R 21 , R 22 , and R 23 Each of these is independently a substituted hydrocarbyl group having 1 to 10 carbon atoms. Also, R 21 , R22 , and R 23 Any two of these may be joined together to form a ring. u is an integer of 0 or 1. In equation (ALU-2), R 24 , and R 25 Each of these is independently a hydrogen atom or a substituted, carbon-1 to carbon-10 hydrocarbyl group. 26 is a hydrocarbyl group having 1 to 20 carbon atoms, or R 24 , or R 25 They bond with each other, and the carbon atoms and X that they bond to. a Together with the above, a heterocyclic group having 3 to 20 carbon atoms may be formed. Furthermore, the -CH2- contained in the hydrocarbyl group and the heterocyclic group may be replaced with -O- or -S-. a represents an oxygen atom or a sulfur atom. v is an integer of 0 or 1. * represents a bond with an adjacent oxygen atom.

[0065] The aforementioned R 21 ~R 26 The hydrogen atoms may be further substituted. 21 ~R 26 However, if the compound has an aromatic ring such as a benzene ring, naphthalene ring, or indene ring, some or all of the hydrogen atoms of the aromatic ring may be substituted. Examples of such substituents include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, methyl groups, methoxy groups, trifluoromethyl groups, trifluoromethoxy groups, nitro groups, and cyano groups.

[0066] The structures of the acid-unstable group represented by formula (ALU-1) include, but are not limited to, those shown below. * indicates a bond with an adjacent oxygen atom. [ka]

[0067] [ka]

[0068] [ka]

[0069] The following are examples of structures of the acid-unstable group represented by formula (ALU-2), but are not limited to these. * indicates a bond with an adjacent oxygen atom. The oxygen atom in the following structures may also be a sulfur atom. [ka]

[0070] Examples of cations of the sulfonium salt represented by formula (1) include, but are not limited to, those listed below. [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077]

change

[0078]

change

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085]

change

[0086] In formula (1), X -This is a non-nucleophilic counterion that does not contain polymerizable groups. Preferably, the non-nucleophilic counterion is a sulfonic acid anion, an imido acid anion, or a methido acid anion. Specific examples of sulfonate anions (sulfonate ions), imidate anions (imide ions), and methidate anions (methide ions) 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.

[0087] Other examples of the aforementioned non-nucleophilic counterions include anions selected from the following formulas (1A) to (1D). [ka]

[0088] In formula (1A), R fa R is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (1A') described later. fa1 Examples of hydrocarbyl groups represented by the symbol shown are similar to those exemplified.

[0089] The anion represented by formula (1A) is preferably the one represented by formula (1A') below. [ka]

[0090] In formula (1A’), Q 1 and Q 2 are each independently a hydrogen atom, a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms, but in order to improve solvent solubility, at least one of them is preferably a trifluoromethyl group. k is an integer of 0 to 4, but is particularly preferably 1. R fa1 is a hydrocarbyl group having 1 to 50 carbon atoms which may contain a heteroatom. As the heteroatom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, etc. are preferable, and an oxygen atom is more preferable. As the hydrocarbyl group, those having 6 to 30 carbon atoms are particularly preferable from the viewpoint of obtaining high resolution in fine pattern formation.

[0091] In formula (1A’), the hydrocarbyl group represented by R fa1 may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 38 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group, nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, icosanyl group; cyclic saturated hydrocarbyl groups having 3 to 38 carbon atoms such as cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-adamantylmethyl group, norbornyl group, norbornylmethyl group, tricyclodecanyl group, tetracyclododecanyl group, tetracyclododecanylmethyl group, dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms such as allyl group, 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms such as phenyl group, 1-naphthyl group, 2-naphthyl group, 9-fluorenyl group; aralkyl groups having 7 to 38 carbon atoms such as benzyl group, diphenylmethyl group; groups obtained by combining these, and the like.

[0092] 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.

[0093] In formula (1A'), L a1 The bond can be a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, or a carbamate bond, but from a synthetic viewpoint, an ether bond or an ester bond is preferred, and an ester bond is even more preferred.

[0094] The anions represented by formula (1A) include, but are not limited to, those listed below. Note that in the formula below, Q 1 This is the same as above, and Ac is an acetyl group. [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] In formula (1B), 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 (1A'). fa1 Examples of hydrocarbyl groups represented by R include those similar to those exemplified. fb1 and R fb2 Preferably, R is a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 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.

[0103] In formula (1C), 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 (1A'). 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.

[0104] In formula (1D), R fd R is a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R in formula (1A'). fa1 Examples of hydrocarbyl groups represented by the same formula as those exemplified above include those shown.

[0105] The anions represented by formula (1D) include, but are not limited to, those listed below. [ka]

[0106] [ka]

[0107] Examples of the aforementioned non-nucleophilic counterions include anions having an aromatic ring substituted with an iodine or bromine atom. Such anions are represented by the following formula (1E). [ka]

[0108] In equation (1E), x is an integer satisfying 1 ≤ x ≤ 3. y and z are integers satisfying 1 ≤ y ≤ 5, 0 ≤ z ≤ 3, and 1 ≤ y + z ≤ 5. y is preferably an integer satisfying 1 ≤ y ≤ 3, and more preferably 2 or 3. z is preferably an integer satisfying 0 ≤ z ≤ 2.

[0109] In formula (1E), X BI x is an iodine atom or a bromine atom, and when x and / or y are 2 or more, they may be the same or different from each other.

[0110] In formula (1E), 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.

[0111] In formula (1E), L 2 When x is 1, it is a single bond or a divalent linking group having 1 to 20 carbon atoms, and when x is 2 or 3, it is a (x+1) valent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0112] In formula (1E), R 8This 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-C10 hydrocarbyloxycarbonyl group, a C2-C20 hydrocarbylcarbonyloxy group, or a C1-C20 hydrocarbylsulfonyloxy group, or -N(R 8A )(R 8B ), -N(R 8C )-C(=O)-R 8D Or -N(R 8C )-C(=O)-OR 8D That is. R 8A and R 8B Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 8C 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. 8D This is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxyl group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When x and / or z is 2 or more, each R 8 They may be the same or different from one another.

[0113] Of these, R 8Examples include hydroxyl groups, -N(R 8C )-C(=O)-R 8D , -N(R 8C )-C(=O)-OR 8D Fluorine atoms, chlorine atoms, bromine atoms, methyl groups, methoxy groups, etc. are preferred.

[0114] In formula (1E), Rf 1 ~Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one of these is either a fluorine atom or a trifluoromethyl group. Also, Rf 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. Note that Rf 1 ~Rf 4 This applies only in the above formula (1E).

[0115] The anions of the onium salt represented by formula (1E) include, but are not limited to, the following. Note that in the following formula, X BI This is the same as described above. [ka]

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120]

change

[0121]

change

[0122]

change

[0123]

change

[0124]

change

[0125]

change

[0126]

change

[0127]

change

[0128]

change

[0129]

change

[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] [ka]

[0138] As the non-nucleophilic counterion, you can also use a fluorobenzenesulfonic acid anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, an anion having a mechanism for decomposition by acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-070692, an anion having a cyclic ether group as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935, or an anion as described in Japanese Patent Application Publication No. 2018-092159.

[0139] As the non-nucleophilic counterions, anions of bulky benzenesulfonic acid derivatives that do not contain fluorine atoms, as described in Japanese Patent Publication No. 2006-276759, Japanese Patent Publication No. 2015-117200, Japanese Patent Publication No. 2016-65016, and Japanese Patent Publication No. 2019-202974, as well as benzenesulfonic acid anions or alkylsulfonic acid anions that do not contain fluorine atoms bonded to an aromatic group containing an iodine atom, as described in Japanese Patent Publication No. 6645464.

[0140] As the non-nucleophilic counterion, other options include the bissulfonic acid anion described in Japanese Patent Publication No. 2015-206932, the sulfonamide or sulfonimide anion described in International Publication No. 2020 / 158366, which has a sulfonic acid on one end and a different sulfonamide or sulfonimide on the other, and the sulfonate anion described in Japanese Patent Publication No. 2015-024989.

[0141] Specific examples of the sulfonium salt of the present invention include any combination of the anion and cation described above.

[0142] The sulfonium salt (1) of the present invention can be synthesized by known methods. For example, first, a sulfonium salt containing the sulfonium cation can be synthesized by reacting the corresponding sulfoxide with a Grignard reagent in the presence of a halosilicon reagent. Next, the synthesized sulfonium salt can be converted to the desired sulfonium salt by a salt exchange reaction with the corresponding anion. Salt exchange with the corresponding anion can be easily carried out by known methods, for example, by referring to Japanese Patent Application Publication No. 2007-145797.

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

[0144] The structural features of the sulfonium salt of the present invention include an acid-unstable group bonded in place of a hydrogen atom on the hydroxyl group on the aromatic ring of the sulfonium cation, and a substituent containing a fluorine atom, both of which are bonded to adjacent carbon atoms. The acid-unstable group in the exposed area undergoes a deprotection reaction with the generated acid, generating aromatic hydroxyl groups. This improves the contrast between the exposed and unexposed areas. In addition, the adjacent fluorine atom-containing substituent improves the solubility of the sulfonium salt itself in the resist solvent and, due to its electron-withdrawing properties, increases the acidity of the aromatic hydroxyl groups generated in the exposed area. When the resist film is developed with an alkaline developer after exposure, the affinity between the generated aromatic hydroxyl groups and the alkaline developer is improved, allowing the exposed area to be effectively removed by the developer. Furthermore, the aromatic hydroxyl group adjacent to the fluorine atom-containing substituent is thought to reduce swelling by the alkaline developer because, due to the water-repellent effect of the fluorine atom, it does not draw the alkaline developer to the unexposed area as much as a carboxyl group. This suppresses the collapse of the resist pattern in the unexposed area. Due to these synergistic effects, when using the sulfonium salt of the present invention, it is possible to form patterns with high dissolution contrast, excellent LWR for line patterns and CDU for hole patterns, and strong resistance to pattern collapse, making it suitable as a positive-type resist material.

[0145] [Photoacid Generator] Thus, the sulfonium salt can be suitably used as a photoacid generator.

[0146] [Resist composition] The present invention provides a photoacid generator comprising the above-mentioned sulfonium salt and a resist composition containing the photoacid generator. The resist composition of the present invention is preferably a chemically amplified resist composition. The resist composition of the present invention will be described below using a chemically amplified resist composition as an example.

[0147] The chemically amplified resist composition of the present invention is not particularly limited as long as it contains a photoacid generator consisting of the above sulfonium salt, (A) A photoacid generator consisting of a sulfonium salt represented by formula (1), (B) Base polymer, and (C) May contain organic solvents.

[0148] The chemically amplified resist composition of the present invention may further, if necessary, (D) Quencher, (E) Other photoacid generators It may also include, and if necessary, (F) A surfactant that is insoluble or sparingly soluble in water and soluble in alkaline developer, and / or a surfactant that is insoluble or sparingly soluble in water and alkaline developer. It may also include, and if necessary, (G) Other ingredients It may include.

[0149] [(A) Photoacid Generator] Component (A) is a photoacid generator consisting of a sulfonium salt represented by formula (1). As described above, due to the structural characteristics of the sulfonium salt, the resist composition of the present invention has high dissolution contrast, excellent LWR for line patterns and CDU for hole patterns, and enables pattern formation that is resistant to pattern collapse.

[0150] The content of the photoacid generator, which consists of a sulfonium salt represented by formula (1) of component (A), is preferably 0.1 to 40 parts by mass, and more preferably 0.5 to 30 parts by mass, relative to 80 parts by mass of the base polymer described later. When the content of component (A) is within the above range, the sensitivity and resolution are good, and there is no risk of foreign matter problems occurring after development or peeling of the resist film, so it is preferable. The photoacid generator of component (A) may be used alone or in combination of two or more types.

[0151] [(B) Base polymer] The base polymer of component (B) is not particularly limited, but may include, for example, a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0152] In equations (a1) and (a2), R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. A This is a single bond, (main chain)-C(=O)-OZ A1 - Or a carbon-1 to carbon-10 alkoxy group which may contain a fluorine atom, or a phenylene group or naphthylene group which may contain a halogen atom. A1 This is a C1-C10 alkoxy group which may contain a heteroatom or a fluorine atom, a hydroxyl group which may contain an ether bond which may contain an ester bond which may contain a lactone ring, a linear, branched or cyclic C1-C20 alkanediyl group (aliphatic hydrocarbylene group) which may contain a lactone ring, a phenylene group, or a naphthylene group. B The bond is either a single bond or (main chain)-C(=O)-O-. A and X B These are, independently, acid-unstable groups. Here, "(main chain)" represents the bond between the above group and the polymer main chain.

[0153] In formula (a2), R B This is a monovalent hydrocarbon group (hydrocarbyl group) having 1 to 20 carbon atoms, which may contain heteroatoms. The monovalent hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R 12 Examples similar to those exemplified in the explanation can be given. n is an integer from 0 to 4, preferably 0 or 1.

[0154] In equations (a1) and (a2), X A and X B Examples of acid-unstable groups represented by include those described in Japanese Patent Publication No. 2013-80033 and Japanese Patent Publication No. 2013-83821.

[0155] 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.)

[0156] In equations (AL-1) and (AL-2), R L1 and R L2 Each of these is independently a saturated hydrocarbyl group having 1 to 40 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. The saturated hydrocarbyl group is preferably one having 1 to 20 carbon atoms.

[0157] In formula (AL-1), a is an integer between 0 and 10, preferably between 1 and 5.

[0158] In formula (AL-2), R L3 and R L4 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, or fluorine atoms. The hydrocarbyl group may be linear, branched, or cyclic. Also, R L2 , R L3 and R L4 Any two of these may bond with each other to form a ring having 3 to 20 carbon atoms, together with the carbon atom to which they are bonded, or a carbon atom and an oxygen atom. The ring is preferably a ring having 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0159] In formula (AL-3), R L5 , R L6 and R L7 Each of these is independently a saturated hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be linear, branched, or cyclic. Also, R L5 , R L6 and R L7 Any two of these may bond with each other to form a ring with 3 to 20 carbon atoms. The ring is preferably a ring with 4 to 16 carbon atoms, and an alicyclic ring is particularly preferred.

[0160] The repeating unit a1 can be, but is not limited to, the following. Note that in the following formula, R A and X A This is the same as described above. [ka]

[0161] [ka]

[0162] The repeating unit a2 can be, but is not limited to, the following. Note that in the following formula, R A and X B This is the same as described above.

[0163] [ka]

[0164] Preferably, the base polymer further contains a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0165] In equations (b1) and (b2), R A , Z B The same applies as above. Y A m is a polar group comprising a hydrogen atom, or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a sulfonic acid amide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic acid anhydride. m is an integer from 1 to 4.

[0166] The above Y A This may be a polar group comprising a hydrogen atom or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride.

[0167] The repeating unit b1 can be, but is not limited to, the following. Note that in the following formula, R A This is the same as described above.

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] The repeating unit b2 can be, but is not limited to, the following. Note that in the following formula, R A This is the same as described above. [ka]

[0177] [ka]

[0178] [ka]

[0179] As for the repeating unit b1 or b2, in ArF lithography, it is particularly preferable to have a lactone ring as a polar group, and in KrF lithography, EB lithography, and EUV lithography, it is preferable to have a phenol moiety.

[0180] The base polymer may further contain repeating units represented by any of the following formulas (C1) to (C4) (hereinafter also referred to as repeating units c1 to c4, respectively). [ka] (In the formula, R A (This is the same as above.)

[0181] In formulas (C1) to (C4), R A This is the same as above. Z 1 This is a single bond or a phenylene group. 2 This is a single bond, *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or *-OZ 21 - is Z 21This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 - is Z 31 This is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. 4 This refers to a single bond, a methylene group, or *-Z 41 -C(=O)-O- Z 41 This is a C1-C20 hydrocarbylene group which may contain heteroatoms, ether bonds, or ester bonds. 5 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-OZ. 51 -, *-C(=O)-N(H)-Z 51 -or *-OZ 51 - is Z 51 This is a phenylene group substituted with an aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, or trifluoromethyl group having 1 to 6 carbon atoms, and may contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * represents a bond with a carbon atom in the main chain or a group on the main chain side.

[0182] Z 21 , Z 31 and Z 51 The aliphatic hydrocarbylene group represented by can be linear, branched, or cyclic, and a specific example is Z in formula (a1). A Examples similar to those given in the explanation can be cited.

[0183] Z 41 The hydrocarbylene group represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples are listed below, but are not limited to these. [ka] (In the equation, dashed lines represent connections.)

[0184] In formula (c1), R 21 and R 22 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 21 and R 22 The hydrocarbyl group represented by can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated hydrocarbyl groups such as cyclohexenyl; aryl groups such as phenyl, naphthyl, and thienyl; aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these, but aryl groups are preferred. Furthermore, some of the hydrogen atoms of the hydrocarbyl group may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and heteroatom-containing groups such as oxygen atoms, sulfur atoms, and nitrogen atoms may be interposed between the carbon atoms of these groups. As a result, the product may contain hydroxyl groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, and the like.

[0185] Also, R 21 and R 22 These atoms may bond with each other to form a ring with the sulfur atom to which they are bonded. Specifically, examples include those represented by the following formula. [ka]

[0186] Examples of cations for the repeating unit c1 include, but are not limited to, those listed below. Note that in the following formula, R A This is the same as described above. [ka]

[0187] [ka]

[0188] [ka]

[0189] [ka]

[0190] In formula (c1), M - X is a non-nucleophilic counterion. The non-nucleophilic counterion is X in equation (1). - Similar examples include the above.

[0191] In formula (c2), L 1 These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Of these, ether bonds, ester bonds, and carbonyl groups are preferred from a synthetic viewpoint, and ester bonds and carbonyl groups are more preferred.

[0192] In formula (c2), Rf 1 and Rf 2 Each of these is independently a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. Of these, Rf 1 and Rf 2 To increase the acid strength of the generated acid, it is preferable that all atoms be fluorine atoms. Rf 3 and Rf 4Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. Of these, Rf is used to improve solvent solubility. 3 and Rf 4 At least one of them is preferably a trifluoromethyl group.

[0193] In equation (c2), c is an integer between 0 and 3, but 1 is preferred.

[0194] The repeating unit anions represented by formula (c2) include, but are not limited to, the following. Note that in the following formula, R A This is the same as described above.

[0195] [ka]

[0196] [ka]

[0197] [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] In formula (c3), L 1 The same applies as above.

[0202] In formula (c3), Rf5 and Rf 6 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. Of these, Rf is used to improve solvent solubility. 5 and Rf 6 At least one of them is preferably a trifluoromethyl group.

[0203] In equation (c3), c is an integer between 0 and 3, but 1 is preferred.

[0204] The repeating unit anions represented by formula (c3) include, but are not limited to, the following. Note that in the following formula, R A This is the same as described above.

[0205] [ka]

[0206] [ka]

[0207] [ka]

[0208] The repeating unit anions represented by formula (c4) include, but are not limited to, the following. Note that in the following formula, R A This is the same as described above.

[0209] [ka]

[0210] In formulas (c2) to (c4), A +This is an onium cation. Examples of the onium cation include ammonium cations, sulfonium cations, and iodonium cations, but sulfonium cations and iodonium cations are preferred, and more preferably sulfonium cations represented by the following formula (cation-1) and iodonium cations represented by the following formula (cation-2). [ka]

[0211] In formulas (cation-1) and (cation-2), R 11 ~R 15 Each of these is independently a C1-C30 hydrocarbyl group which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; cyclic saturated hydrocarbyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups such as cyclohexenyl groups; aryl groups such as phenyl, naphthyl, and thienyl groups; aralkyl groups such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, but aryl groups are preferred. Furthermore, some of the hydrogen atoms of the hydrocarbyl group may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and heteroatom-containing groups such as oxygen atoms, sulfur atoms, and nitrogen atoms may be interposed between the carbon atoms of these groups, and as a result, the group may contain hydroxyl groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, etc. Note that R in this context 11 ~R 15This applies only in the above formulas (cation-1) and (cation-2).

[0212] Also, R 11 and R 12 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. In this case, examples of sulfonium cations represented by formula (cation-1) include those represented by the following formula. [ka] (In the formula, the dashed line represents R 13 (This is a combination of the two.)

[0213] Examples of sulfonium cations represented by formula (cation-1) include, but are not limited to, those listed below.

[0214] [ka]

[0215] [ka]

[0216] [ka]

[0217] [ka]

[0218] [ka]

[0219] [ka]

[0220]

change

[0221]

change

[0222]

change

[0223]

change

[0224]

change

[0225]

change

[0226]

change

[0227]

change

[0228]

change

[0229]

change

[0230]

change

[0231] [ka]

[0232] [ka]

[0233] Examples of iodonium cations represented by formula (cation-2) include, but are not limited to, those listed below. [ka]

[0234] Specific examples of the repeating units represented by formulas (c1) to (c4) include any combination of the anions and cations mentioned above.

[0235] From the viewpoint of controlling acid diffusion, repeating units c2, c3, and c4 are preferred as repeating units c1 to c4, repeating units c2 and c4 are more preferred from the viewpoint of the acid strength of the generated acid, and repeating unit c2 is even more preferred from the viewpoint of solvent solubility.

[0236] The base polymer may further contain repeating units (hereinafter also referred to as repeating unit d) having a structure in which a hydroxyl group is protected by an acid-unstable group. The repeating unit d is not particularly limited as long as it has one or more structures in which a hydroxyl group is protected and the protecting group decomposes upon the action of an acid to generate a hydroxyl group, but it is preferably represented by the following formula (d1). [ka]

[0237] In formula (d1), R A This is the same as above. R 41 R is a (d+1) valent hydrocarbon group having 1 to 30 carbon atoms, which may contain heteroatoms.42 is an acid-unstable group. d is an integer between 1 and 4.

[0238] In formula (d1), R 42 The acid-unstable group represented by can be any group that is deprotected by the action of an acid and generates a hydroxyl group. 42 The structure is not particularly limited, but acetal structures, ketal structures, alkoxycarbonyl groups, and alkoxymethyl groups represented by the following formula (d2) are preferred, and alkoxymethyl groups represented by the following formula (d2) are particularly preferred. [ka] (In the equation, the dashed line represents a coupling. R 43 (This refers to a hydrocarbyl group with 1 to 15 carbon atoms.)

[0239] R 42 Specific examples of the acid-unstable group represented by (d2), the alkoxymethyl group represented by (d2), and the repeating unit d are the same as those exemplified in the description of the repeating unit d described in Japanese Patent Application Publication No. 2020-111564.

[0240] The base polymer may further contain repeating units e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Examples of monomers that give repeating units e are, but are not limited to, those listed below. [ka]

[0241] The base polymer may further contain repeating units f derived from indan, vinylpyridine, or vinylcarbazole.

[0242] In the polymer of the present invention, the content ratios of the repeating units a1, a2, b1, b2, c1 to c4, d, e, and f are preferably 0 < a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ b1 ≤ 0.6, 0 ≤ b2 ≤ 0.6, 0 ≤ c1 ≤ 0.4, 0 ≤ c2 ≤ 0.4, 0 ≤ c3 ≤ 0.4, 0 ≤ c4 ≤ 0.4, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.3, and 0 ≤ f ≤ 0.3, and more preferably 0 < a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ b1 ≤ 0.5, 0 ≤ b2 ≤ 0.5, 0 ≤ c1 ≤ 0.3, 0 ≤ c2 ≤ 0.3, 0 ≤ c3 ≤ 0.3, 0 ≤ c4 ≤ 0.3, 0 ≤ d ≤ 0.3, 0 ≤ e ≤ 0.3, and 0 ≤ f ≤ 0.3.

[0243] The weight average molecular weight (Mw) of the polymer is preferably from 1,000 to 500,000, more preferably from 3,000 to 100,000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of a decrease in resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene-equivalent measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0244] Furthermore, since the influence of the molecular weight distribution (Mw / Mn) of the polymer becomes greater as the pattern rules become finer, in order to obtain a resist composition suitably used for fine pattern dimensions, Mw / Mn is preferably narrowly dispersed in the range of 1.0 to 2.0. If it is within the above range, there is little risk of low molecular weight or high molecular weight polymers, and there is no risk of foreign substances being seen on the pattern or the pattern shape deteriorating after exposure.

[0245] To synthesize the polymer, for example, monomers that give the above-described repeating units can be heated in an organic solvent with a radical polymerization initiator added to perform polymerization.

[0246] Examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% of the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, and more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0247] The polymerization initiator may be added to the monomer solution and supplied to the reaction vessel, or an initiator solution may be prepared separately from the monomer solution and each supplied to the reaction vessel independently. Since the polymerization reaction may proceed and a superpolymer may be formed by radicals generated from the initiator during the waiting time, it is preferable from a quality control viewpoint to prepare the monomer solution and the initiator solution independently and add them dropwise. The acid-unstable group may be used as is, introduced into the monomer, or it may be protected or partially protected after polymerization. In addition, known chain transfer agents such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination to adjust the molecular weight. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% of the total amount of monomers to be polymerized.

[0248] In the case of monomers containing hydroxyl groups, the hydroxyl groups may be substituted with acetal groups that are easily deprotected by acids such as ethoxyethoxy groups during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, they may be substituted with acetyl groups, formyl groups, pivaloyl groups, etc., and then alkaline hydrolysis may be performed after polymerization.

[0249] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, hydroxystyrene or hydroxyvinylnaphthalene may be polymerized by heating in an organic solvent with a radical polymerization initiator. Alternatively, acetoxystyrene or acetoxyvinylnaphthalene may be used, and after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to obtain polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0250] 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.

[0251] The amount of each monomer in the monomer solution can be appropriately set, for example, to achieve a preferred content ratio of the repeating units described above.

[0252] The polymer obtained by the above manufacturing method may be treated as a final product if it is a reaction solution obtained by a polymerization reaction, or as a final product if it is a powder obtained by a purification process such as a reprecipitation method in which the polymerization solution is added to a poor solvent and a powder is obtained. However, from the viewpoint of work efficiency and quality stabilization, it is preferable to treat the polymer solution obtained by dissolving the powder obtained by the purification process in a solvent as the final product.

[0253] Specific examples of solvents used in this process include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of Japanese Patent Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether. Examples include ethers such as ethers; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling point alcoholic solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol; and mixed solvents thereof.

[0254] In the polymer solution, the concentration of the polymer is preferably 0.01 to 30% by mass, and more preferably 0.1 to 20% by mass.

[0255] It is preferable to filter the reaction solution or polymer solution. Filtering removes foreign matter and gel that may cause defects, which is effective in stabilizing quality.

[0256] Examples of filter materials used in the aforementioned filter filtration include fluorocarbon, cellulose, nylon, polyester, and hydrocarbon materials. However, in the filtration process of the resist composition, filters made of fluorocarbon materials such as Teflon (registered trademark), hydrocarbon materials such as polyethylene and polypropylene, or nylon are preferred. The pore size of the filter can be appropriately selected according to the desired level of cleanliness, but is preferably 100 nm or less, and more preferably 20 nm or less. These filters may be used individually or in combination. The filtration method may involve passing the solution through only once, but it is more preferable to circulate the solution and filter it multiple times. The filtration process can be carried out in any order and number of times in the polymer manufacturing process, but it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0257] The aforementioned polymer may be used alone, or two or more polymers with different composition ratios, Mw, and / or Mw / Mn may be used in combination. In addition, the (B) base polymer may include hydrogenated ring-opening metathesis polymers in addition to the aforementioned polymers, and for this, those described in Japanese Patent Publication No. 2003-66612 may be used.

[0258] [(C) Organic Solvents] The organic solvent for component (C) is not particularly limited as long as it can dissolve the components described above and the components described later. Examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; keto alcohols such as DAA; ethers such as PGME, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as GBL, and mixed solvents thereof.

[0259] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixtures thereof are preferred, as they exhibit particularly excellent solubility of the base polymer of component (B).

[0260] The amount of organic solvent used is preferably 200 to 5,000 parts by mass, and more preferably 400 to 3,500 parts by mass, per 80 parts by mass of (B) base polymer. (C) The organic solvent may be used alone or as a mixture of two or more types.

[0261] [(D) Quencher] (D) Examples of quenchers include onium salts represented by the following formulas (5) or (6). [ka]

[0262] In formula (5), R q1This is a monovalent hydrocarbon group (hydrocarbyl group) having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. In formula (6), R q2 This is a monovalent hydrocarbon group (hydrocarbyl group) having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom.

[0263] R q1 Specifically, the hydrocarbyl groups represented by include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6 Examples include cyclic saturated hydrocarbyl groups such as decanyl groups and adamantyl groups; and aryl groups such as phenyl groups, naphthyl groups, and anthracenyl groups. Furthermore, some or all of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, or some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the group may contain hydroxyl groups, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, etc.

[0264] R q2 Specifically, the hydrocarbyl group represented by R q1 In addition to the substituents exemplified as specific examples, other examples include fluorinated alkyl groups such as trifluoromethyl and trifluoroethyl groups, and fluorinated aryl groups such as pentafluorophenyl and 4-trifluoromethylphenyl groups.

[0265] The anions of the onium salt represented by formula (5) include, but are not limited to, those listed below.

[0266] [ka]

[0267] [ka]

[0268] The anions of the onium salt represented by formula (6) include, but are not limited to, those listed below.

[0269] [ka]

[0270] [ka]

[0271] In equations (5) and (6), MQ + This is an onium cation. The onium cation is preferably one represented by the following formulas (cation-1), (cation-2), or (cation-3). [ka]

[0272] For equations (cation-1) and (cation-2), in equations (c2) to (c4), A + Similar examples include (cation-3), R 16 ~R 19 Each of these is independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain heteroatoms. Also, R 16 and R 17These may bond with each other to form a ring with the nitrogen atom to which they are bonded. The hydrocarbyl group is R in formulas (cation-1) and (cation-2). 11 ~R 15 Examples similar to those given in the explanation can be cited.

[0273] MQ + In the onium cation represented by (cation-3), the following are examples of ammonium cations, but are not limited to these. [ka]

[0274] Specific examples of onium salts represented by formula (5) or (6) include any combination of the anions and cations mentioned above. These onium salts can be easily prepared by ion exchange reactions using known organic chemical methods. For ion exchange reactions, refer to, for example, Japanese Patent Application Publication No. 2007-145797.

[0275] The onium salt represented by formula (5) or (6) acts as a quencher in the chemically amplified resist composition of the present invention. This is because each counteranion of the onium salt is a conjugate base of a weak acid. Here, a weak acid refers to an acidity that is not sufficient to deprotect the acid-unstable groups of the acid-unstable group-containing units used in the base polymer.

[0276] Onium salts represented by formulas (5) or (6) function as quenchers when used in combination with onium salt-type photoacid generators that have a conjugate base of a strong acid, such as a sulfonic acid with fluorinated α-position, as a counteranion. That is, when an onium salt that generates a strong acid, such as a sulfonic acid with fluorinated α-position, is used in combination with an onium salt that generates a weak acid, such as an unfluorinated sulfonic acid or carboxylic acid, the strong acid generated from the photoacid generator by high-energy irradiation collides with the onium salt having an unreacted weak acid anion. This results in salt exchange, releasing the weak acid and producing an onium salt with a strong acid anion. In this process, the strong acid is exchanged for a weaker acid with lower catalytic activity, so the acid is seemingly deactivated, allowing for control of acid diffusion.

[0277] Furthermore, as the (D) quencher, an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent Publication No. 6848776, an onium salt having a sulfonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent Publication No. 6583136 and Japanese Patent Application Publication No. 2020-200311, and an onium salt having an iodonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent Publication No. 6274755 can also be used.

[0278] Here, if the photoacid generator that produces a strong acid is an onium salt, as mentioned above, the strong acid produced by high-energy ray irradiation can be exchanged for a weak acid. On the other hand, it is thought that the weak acid produced by high-energy ray irradiation is unlikely to collide with the unreacted onium salt that produces the strong acid and undergo salt exchange. This is due to the phenomenon that onium cations are more likely to form ion pairs with the anions of stronger acids.

[0279] (D) When the onium salt type quencher contains an onium salt represented by formula (5) or (6), its content is preferably 0.1 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 80 parts by mass of the (B) base polymer. If the onium salt type quencher of component (D) is within the above range, the resolution is good and the sensitivity does not decrease significantly, which is preferable. The onium salt represented by formula (5) or (6) can be used alone or in combination of two or more.

[0280] The chemically amplified resist composition of the present invention may further contain a nitrogen-containing quencher. In this invention, a nitrogen-containing quencher is a material that traps the acid generated from the photoacid generator in the chemically amplified resist composition, thereby preventing its diffusion to unexposed areas and forming a desired pattern.

[0281] Furthermore, examples of nitrogen-containing quenchers for component (D) include primary, secondary, or tertiary amine compounds, particularly those having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond, as described in paragraphs

[0146] to

[0164] of Japanese Patent Publication No. 2008-111103. Also, examples include compounds in which a primary or secondary amine is protected with a carbamate group, such as the compound described in Japanese Patent Publication No. 3790649. Thus, the resist composition of the present invention may further contain an amine compound.

[0282] Alternatively, a sulfonium sulfonate salt having a nitrogen-containing substituent may be used as a nitrogen-containing quencher. Such a compound functions as a quencher in the unexposed area and loses its quenching ability in the exposed area through neutralization with its own generated acid, functioning as a so-called photodecayable base. By using a photodecayable base, the contrast between the exposed and unexposed areas can be further enhanced. For examples of photodecayable bases, refer to Japanese Patent Publication No. 2009-109595, Japanese Patent Publication No. 2012-46501, etc.

[0283] If a nitrogen-containing quencher of component (D) is included, its content is preferably 0.001 to 12 parts by mass, and more preferably 0.01 to 8 parts by mass, per 80 parts by mass of the base polymer (B). The nitrogen-containing compound can be used alone or in combination of two or more.

[0284] [(E) Other photoacid generators] The chemically amplified resist composition of the present invention may contain a photoacid generator other than component (A) (hereinafter also referred to as "other photoacid generator") as component (E). The other photoacid generator is not particularly limited as long as it is a compound that generates acid upon irradiation with high-energy rays. Suitable other photoacid generators include those represented by the following formulas (3) or (4). [ka]

[0285] In formulas (3) and (4), R 101 ~R 105 Each of these is independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Also, R 101 , R 102 and R 103 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded. The hydrocarbyl group is R in formulas (cation-1) and (cation-2). 11 ~R 15 Examples similar to those given in the explanation can be cited.

[0286] In formula (3), the sulfonium cation is the same as the one exemplified as the sulfonium cation represented by formula (cation-1).

[0287] In formula (4), the iodonium cation is the same as the iodonium cation exemplified in formula (cation-2).

[0288] In equations (3) and (4), Xa -X in equation (1) - Similar examples include the above.

[0289] Furthermore, as an additional photoacid generator for component (E), one represented by the following formula (V) is also preferred. [ka]

[0290] In formula (V), R 201 and R 202 Each of these is independently a hydrocarbyl group having 1 to 30 carbon atoms, which may contain heteroatoms. 203 This is a hydrocarbylene group having 1 to 30 carbon atoms, which may contain heteroatoms. Also, R 201 , R 202 and R 203 Any two of these may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0291] 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 C1-C30 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, oxanorbornyl, and tricyclo[5.2.1.0 2,6Examples include cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as decanyl and adamantyl groups; aryl groups having 6 to 30 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, tert-butylnaphthyl, and anthracenyl groups; and groups obtained by combining these. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- groups constituting 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, the material may contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, and the like.

[0292] 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 Examples include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as yl groups, cyclohexanediyl groups, norbornanediyl groups, and adamantanediyl groups; and cyclic unsaturated hydrocarbylene groups such as phenylene groups, methylphenylene groups, ethylphenylene groups, n-propylphenylene groups, isopropylphenylene groups, n-butylphenylene groups, isobutylphenylene groups, sec-butylphenylene groups, tert-butylphenylene groups, naphthylene groups, methylnaphthylene groups, ethylnaphthylene groups, n-propylnaphthylene groups, isopropylnaphthylene groups, n-butylnaphthylene groups, isobutylnaphthylene groups, sec-butylnaphthylene groups, and tert-butylnaphthylene groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, and some of the -CH2- groups constituting the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, resulting in the inclusion of a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. The heteroatom is preferably an oxygen atom.

[0293] In formula (V), L AThis is a 1-20 carbon atom hydrocarbylene group which may contain single bonds, ether bonds, or heteroatoms. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R 203 Examples of hydrocarbylene groups represented by the same formula as those exemplified above include the same groups as those shown.

[0294] In formula (V), 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.

[0295] The photoacid generator represented by formula (V) is preferably the one represented by formula (V') below. [ka]

[0296] In formula (V'), L A The same as above. X e R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 Each of these is a hydrocarbyl group having 1 to 20 carbon atoms, which may 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 (1). 12 Similar examples can be given. 1 and m 2 Each of these is an integer from 0 to 5, and m 3 This is an integer between 0 and 4.

[0297] Examples of photoacid generators represented by formula (V) include those similar to those exemplified as photoacid generators represented by formula (2) in Japanese Patent Publication No. 2017-026980.

[0298] Among the other photoacid generators mentioned above, those containing anions represented by formula (1A') or (1D) are particularly preferred because they exhibit low acid diffusion and excellent solubility in solvents. Furthermore, those represented by formula (V') are particularly preferred because they exhibit extremely low acid diffusion.

[0299] If the photoacid generator of component (E) is included, its content is preferably 0.1 to 40 parts by mass, and more preferably 0.5 to 20 parts by mass, per 80 parts by mass of the base polymer (B). If the amount of photoacid generator of component (E) is within the above range, the resolution is good and there is no risk of foreign matter problems occurring after development or peeling of the resist film, so it is preferable. The photoacid generator of component (E) may be used alone or in combination of two or more types.

[0300] [(F) A surfactant that is insoluble or sparingly soluble in water and soluble in alkaline developer, and / or a surfactant that is insoluble or sparingly soluble in water and alkaline developer] The chemically amplified resist composition of the present invention may further contain (F) a surfactant that is insoluble or sparingly soluble in water and soluble in an alkaline developer, and / or a surfactant that is insoluble or sparingly soluble in both water and an alkaline developer. Examples of such surfactants can be found in Japanese Patent Application Publication No. 2010-215608 and Japanese Patent Application Publication No. 2011-16746.

[0301] As surfactants that are insoluble or poorly soluble in water and alkaline developer, among the surfactants described in the above publication, FC-4430 (manufactured by 3M), Surflon® S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Orfin® E1004 (manufactured by Nisshin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and oxetane ring-opening polymers represented by the following formula (surf-1) are preferred. [ka]

[0302] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), notwithstanding the preceding description. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of such aliphatic groups include the divalent ethylene group, 1,4-butylene group, 1,2-propylene group, 2,2-dimethyl-1,3-propylene group, and 1,5-pentylene group, while examples of trivalent or tetravalent aliphatic groups are listed below. [ka] (In the formula, the dashed lines represent bonds, which are substructures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0303] Among these, the 1,4-butylene group and the 2,2-dimethyl-1,3-propylene group are preferred.

[0304] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer from 0 to 3, n is an integer from 1 to 4, and the sum of n and m is the valence of R, an integer from 2 to 4. A is 1. B is an integer from 2 to 25, preferably an integer from 4 to 20. C is an integer from 0 to 10, preferably 0 or 1. Furthermore, the order of each constituent unit in formula (surf-1) is not specified, and they may be bonded in a block-like manner or randomly. For details on the production of partially fluorinated oxetane ring-opening polymer surfactants, please refer to U.S. Patent No. 5,650,483, etc.

[0305] Surfactants that are insoluble or sparingly soluble in water and soluble in alkaline developers have the function of reducing water penetration and leaching by orienting themselves on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, they are useful in suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. Furthermore, they are useful because they become solubilized during alkaline aqueous solution development after exposure and post-exposure bake (PEB), and are less likely to become foreign substances that cause defects. Such surfactants are insoluble or sparingly soluble in water and soluble in alkaline developers, and are polymer-type surfactants, also called hydrophobic resins, and those that have high water repellency and improve water lubricity are particularly preferred.

[0306] Examples of such polymer-type surfactants include those containing at least one repeating unit selected from any of the following formulas (8A) to (8E). [ka]

[0307] In formulas (8A) to (8E), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 R is -CH2-, -CH2CH2-, -O-, or two separated -H atoms. s1 Each of these is independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group or a fluorinated hydrocarbyl group, or an acid-unstable group. s3 If the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. s4 R is a (u+1) valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer from 1 to 3. s5 These are, independently, hydrogen atoms, or -C(=O)-ORs7 It is a group represented by R. s7 This is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 R is a hydrocarbyl group having 1 to 15 carbon atoms or a fluorinated hydrocarbyl group, and an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. Herein, the above R B u applies only in the above equations (8A) to (8E).

[0308] R s1 The hydrocarbyl group represented by can be linear, branched, or cyclic. Specific examples include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, adamantyl, norbornyl, etc. Of these, those with 1 to 6 carbon atoms are preferred.

[0309] R s2 The hydrocarbylene group represented by can be linear, branched, or cyclic, and specific examples include methylene, ethylene, propylene, butylene, and pentylene groups.

[0310] R s3 or R s6 The hydrocarbyl group represented by can be linear, branched, or cyclic, and specific examples include alkyl groups, alkenyl groups, and alkynyl groups, but alkyl groups are preferred. The alkyl group is R s1 In addition to the examples given as hydrocarbyl groups represented by , other examples include n-undecyl group, n-dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc. s3 or R s6Examples of fluorinated hydrocarbyl groups represented by the above-mentioned hydrocarbyl group include groups in which some or all of the hydrogen atoms bonded to the carbon atoms are replaced with fluorine atoms. As mentioned above, ether bonds or carbonyl groups may be interposed between these carbon-carbon bonds.

[0311] R s3 Examples of acid-unstable groups represented by the formulas (AL-1) to (AL-3) mentioned above include tertiary hydrocarbyl groups having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and oxoalkyl groups having 4 to 20 carbon atoms.

[0312] R s4 The (u+1) valent hydrocarbon group or fluorinated hydrocarbon group represented by may be linear, branched, or cyclic, and specific examples include groups obtained by further removing u hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0313] R s7 The fluorinated hydrocarbyl group represented by can be linear, branched, or cyclic, and specifically, it can be a hydrocarbyl group in which some or all of the hydrogen atoms are substituted with fluorine atoms, and specific examples include trifluoromethyl group, 2,2,2-trifluoroethyl group, 3,3,3-trifluoro-1-propyl group, 3,3,3-trifluoro-2-propyl group, 2,2,3,3-tetrafluoropropyl group, 1,1,1 Examples include 3,3,3-hexafluoroisopropyl group, 2,2,3,3,4,4,4-heptafluorobutyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, 2-(perfluorobutyl)ethyl group, 2-(perfluorohexyl)ethyl group, 2-(perfluorooctyl)ethyl group, and 2-(perfluorodecyl)ethyl group.

[0314] The repeating units represented by any of the formulas (8A) to (8E) include, but are not limited to, the following. Note that in the following formulas, R B This is the same as described above. [ka]

[0315] [ka]

[0316] [ka]

[0317] [ka]

[0318] [ka]

[0319] The polymer-type surfactant may further contain other repeating units other than those represented by formulas (8A) to (8E). Examples of other repeating units include those obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. The content of the repeating units represented by formulas (8A) to (8E) in the polymer-type surfactant is preferably 20 mol% or more, more preferably 60 mol% or more, and even more preferably 100 mol% of the total repeating units.

[0320] The Mw of the polymer-type surfactant is preferably 1,000 to 500,000, and more preferably 3,000 to 100,000. The Mw / Mn ratio is preferably 1.0 to 2.0, and more preferably 1.0 to 1.6.

[0321] A method for synthesizing the polymer-type surfactant involves polymerizing a monomer containing unsaturated bonds that provide repeating units represented by formulas (8A) to (8E), and optionally other repeating units, by heating it in an organic solvent with a radical initiator. Examples of organic solvents used during polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid-unstable group may be used as is after being introduced into the monomer, or it may be protected or partially protected after polymerization.

[0322] When synthesizing the polymer-type surfactant, known chain transfer agents such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In that case, the amount of these chain transfer agents added is preferably 0.01 to 10 mol% relative to the total number of moles of monomers to be polymerized.

[0323] If the surfactant component (F) is included, its content is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 10 parts by mass, per 80 parts by mass of the (B) base polymer. If the amount added is 0.1 parts by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, and if it is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is small, and the height of the formed fine pattern is sufficiently maintained.

[0324] [(G) Other ingredients] The chemically amplified resist composition of the present invention may also contain (G) other components such as a compound that decomposes with acid to generate acid (acid-proliferating compound), an organic acid derivative, a fluorine-substituted alcohol, and a compound with an Mw of 3,000 or less whose solubility in the developer changes due to the action of acid (dissolution inhibitor). As the acid-proliferating compound, one can refer to the compounds described in Japanese Patent Publication No. 2009-269953 or Japanese Patent Publication No. 2010-215608. When the acid-proliferating compound is included, its content is preferably 0 to 5 parts by mass, and more preferably 0 to 3 parts by mass, per 80 parts by mass of the (B) base polymer. If the content is too high, it becomes difficult to control acid diffusion, which may lead to deterioration of resolution and pattern shape. As the organic acid derivative, fluorine-substituted alcohol and dissolution inhibitor, one can refer to the compounds described in Japanese Patent Publication No. 2009-269953 or Japanese Patent Publication No. 2010-215608.

[0325] [Pattern formation method] The pattern formation method of the present invention includes the steps of: forming a resist film on a substrate using the chemically amplified resist composition described above; exposing the resist film with high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), or extreme ultraviolet (EUV) with a wavelength of 3 to 15 nm; and developing the exposed resist film using a developer.

[0326] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or substrates for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) can be used.

[0327] The resist film can be formed by, for example, applying the chemically amplified resist composition to a thickness of 0.05 to 2 μm using a method such as spin coating, and then pre-baking it on a hot plate, preferably at 60 to 150°C for 1 to 10 minutes, more preferably at 80 to 140°C for 1 to 5 minutes.

[0328] In the pattern formation method described above, the high-energy beam is preferably 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.

[0329] When exposing the resist film using KrF excimer laser light, ArF excimer laser light, or EUV, a mask is used to form the desired pattern, and the exposure dose is preferably 1 to 200 mJ / cm². 2 More preferably 10-100 mJ / cm² 2 This can be done by irradiating in such a manner. When using EB, the exposure amount is preferably 1 to 300 μC / cm², either using a mask to form the desired pattern or directly. 2 More preferably 10-200 μC / cm 2 Irradiate in such a way that it results in the following.

[0330] In addition to conventional exposure methods, immersion methods can also be used, in which a liquid with a refractive index of 1.0 or higher is interposed between the resist film and the projection lens. In this case, a protective film insoluble in water can also be used.

[0331] The aforementioned water-insoluble protective film is used to prevent leaching from the resist film and to improve the water-repellent properties of the film surface, and there are two main types. One is an organic solvent-removable type that requires removal before alkaline aqueous solution development using an organic solvent that does not dissolve the resist film, and the other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with the soluble parts of the resist film. The latter is particularly preferably based on a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and soluble in alkaline developer, and dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof. Alternatively, the aforementioned water-insoluble and alkaline developer-soluble surfactant can be dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixture thereof.

[0332] PEB may be performed after exposure. PEB can be performed, for example, by heating on a hot plate, preferably at 60-150°C for 1-5 minutes, more preferably at 80-140°C for 1-3 minutes.

[0333] Development is carried out using a developer solution, preferably an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) in an amount of 0.1 to 5% by mass, more preferably 2 to 3% by mass, and by conventional methods such as the dip method, puddle method, or spray method for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, which dissolves the exposed areas and forms the desired pattern on the substrate.

[0334] Furthermore, as a method for pattern formation, after the resist film is formed, a pure water rinse (post-soak) may be performed to extract acid generators from the film surface or wash away particles, or a rinse (post-soak) may be performed to remove water remaining on the film after exposure.

[0335] Furthermore, patterns may be formed using a double patterning method. Examples of double patterning methods include the trench method, in which a 1:3 trench pattern base is processed with the first exposure and etching, and then a 1:3 trench pattern is formed by a second exposure with a shifted position to form a 1:1 pattern; and the line method, in which a first base for a 1:3 isolated pattern is processed with the first exposure and etching, and then a second exposure with a shifted position to process a second base formed beneath the first base for a 1:3 isolated pattern to form a 1:1 pattern with half the pitch.

[0336] In the pattern formation method of the present invention, instead of the alkaline aqueous solution used as the developer, a negative tone development method may be used in which an organic solvent is used to dissolve the unexposed areas.

[0337] This organic solvent development uses the following as a developer: 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotate, ethyl crotate, propyl acetate, methyl propyl formate, butyl formate, isobutyl formate, pentyl formate, methyl valerate, methyl pentenoate, methyl crotate, ethyl crotate, propyl propyl acetate, methyl propyl formate, methyl pentenoate, methyl crotate, ethyl crotate, propyl propyl acetate, methyl propyl formate, methyl pentenoate, methyl crotate, methyl crotate, methyl propyl acetate, methyl propyl formatepropyl acetate, methyl propyl formate, methyl propyl acetate, methyl pentenoate, methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl methyl crotate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl propyl acetate, methyl propyl acetate, methyl pentenoate, methyl methyl crotate, methyl Methyl ropionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenyl acetate, 2-phenylethyl acetate, etc. can be used. These organic solvents may be used individually or in mixtures of two or more. [Examples]

[0338] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The apparatus used is as follows. • IR: NICOLET 6700 manufactured by Thermo Fisher Scientific · 1 H-NMR: ECA-500 manufactured by JEOL Ltd. • MALDI TOF-MS: S3000 manufactured by JEOL Ltd.

[0339] [1] Synthesis of onium salts [Example I-1] Synthesis of PAG-1 (1) Synthesis of intermediate In-1 [ka] Under a nitrogen atmosphere, sodium hydride (55% by mass purity, 43.6 g) was suspended in THF (240 ml), and a solution consisting of 1-methylcyclopentanol (114.2 g) and THF (120 ml) was added dropwise. After the dropwise addition, heating under reflux was carried out for 4 hours to prepare the metal alkoxide. Subsequently, starting material M-1 (193.0 g) was added dropwise, and heating under reflux and aging was carried out for 26 hours. The reaction mixture was cooled in an ice bath, and the reaction was stopped with water (400 ml). The target product was extracted twice with a solvent consisting of toluene (200 ml) and ethyl acetate (200 ml), followed by a normal aqueous work-up. After removing the solvent by distillation, the intermediate In-1 was purified by distillation to obtain 210.3 g as a colorless oil (yield 77%).

[0340] (2) Synthesis of intermediate In-2 [ka] Under a nitrogen atmosphere, the Grignard reagent was prepared from magnesium (3.7 g), THF (120 g), and intermediate In-1 (41.0 g). The reaction system was cooled to below 10°C, and a solution consisting of diphenyl sulfoxide (10.1 g) and methylene chloride (50 g) was added. After the addition, chlorotrimethylsilane (22.6 g) was added dropwise while maintaining an internal temperature of below 20°C. After the dropwise addition, the system was aged for 2 hours at an internal temperature of below 20°C. After aging, the reaction system was cooled, and the reaction was stopped by adding an aqueous solution consisting of ammonium chloride (15 g), 20% hydrochloric acid (15 g), and water (100 g) dropwise. Then, methanol (50 g) and diisopropyl ether (200 g) were added, and the aqueous layer was separated. Furthermore, the separated aqueous layer was washed twice with hexane (200 g). Methylene chloride (100 g) was added to the aqueous layer after washing, and the target product was extracted. Subsequently, a standard aqueous work-up was performed, and the solvent was removed by distillation to obtain 19.5 g of the intermediate In-2 as a colorless oil (yield 85%).

[0341] (3) Synthesis of PAG-1 [ka] Under a nitrogen atmosphere, intermediate In-2 (5.1g), intermediate In-3 (6.5g), methyl isobutyl ketone (60g), methylene chloride (15g), and water (30g) were charged and stirred at room temperature for 30 minutes. The organic layer was separated, washed with water, and then concentrated under reduced pressure. The residue was recrystallized with diisopropyl ether to obtain 8.57g of PAG-1 as white crystals (yield 97%).

[0342] The IR spectral data and TOF-MS results for PAG-1 are shown below. Also, the nuclear magnetic resonance spectrum ( 1 The results of 1H-NMR / DMSO-d6 are shown in Figure 1. IR(D-ATR): ν= 3489, 3064, 2969, 2908, 2853, 1786, 1731, 1601, 1500, 1477, 1448, 1404, 1380, 1324, 1225, 1238, 1181, 1104, 1076, 1035, 1011, 939, 795, 751, 719, 685, 642, 585, 551, 524, 503, 460 cm -1 MALDI TOF-MS: POSITIVE M + 379(C 24 H 24 FOS + equivalent) NEGATIVE M - 503(C 22 H 25 F2O9S - equivalent)

[0343] [Example I-2] Synthesis of PAG-2 [ka]

[0344] PAG-2 was synthesized in the same manner as in Example I-1(3), except that intermediate In-3 was replaced with intermediate In-4 (yield 14.0 g, yield 91%).

[0345] The IR spectral data and TOF-MS results for PAG-2 are shown below. Also, the nuclear magnetic resonance spectrum ( 1 The results of 1H-NMR / DMSO-d6 are shown in Figure 2. IR(D-ATR): ν= 3444, 3061, 2952, 2870, 1597, 1558, 1496, 1478, 1447, 1403, 1383, 1361, 1311, 1296, 1269, 1183, 1125, 1082, 1036, 999, 969, 926, 906, 883, 816, 758, 716, 684, 641, 594, 561, 545, 504 cm -1 MALDI TOF-MS: POSITIVE M + 379(C 24 H 24 FOS + equivalent) NEGATIVE M - 651(C 37 H 47 O6S2 - equivalent)

[0346] [Example I-3] Synthesis of PAG-3 [ka]

[0347] PAG-3 was synthesized in the same manner as in Example I-1(3), except that intermediate In-3 was replaced with intermediate In-5 (yield 10.6g, yield 97%).

[0348] The IR spectral data and TOF-MS results for PAG-3 are shown below. Also, the nuclear magnetic resonance spectrum ( 1 The results of 1H-NMR / DMSO-d6 are shown in Figure 3. IR(D-ATR): ν= 3451, 3060, 2969, 2870, 1749, 1600, 1570, 1497, 1446, 1398, 1379, 1365, 1326, 1268, 1252, 1215, 1199, 1177, 1143, 1122, 1093, 1038, 1001, 931, 871, 812, 750, 717, 685, 656, 640, 617, 591, 561, 527, 504 cm -1 MALDI TOF-MS: POSITIVE M + 379(C 24 H 24 FOS + equivalent) NEGATIVE M - 711(C 17 H 14 I3O5S - equivalent)

[0349] [Example I-4] Synthesis of PAG-4 (1) Synthesis of intermediate In-6 [ka] Intermediate In-6 was synthesized in the same manner as in Examples I-1(1) and I-1(2), except that 1-methylcyclopentanol was replaced with 1-isopropylcyclopentanol (yield 24.8 g, two-step yield 72%).

[0350] (2) Synthesis of PAG-4 [ka] PAG-4 was synthesized in the same manner as in Example I-2, except that intermediate In-2 was replaced with intermediate In-6 (yield 10.3g, yield 97%).

[0351] The IR spectral data and TOF-MS results for PAG-4 are shown below. Also, the nuclear magnetic resonance spectrum ( 1 The results of 1H-NMR / DMSO-d6 are shown in Figure 4. IR(D-ATR): ν= 3060, 2954, 2870, 1599, 1559, 1504, 1476, 1446, 1406, 1386, 1359, 1311, 1288, 1266, 1237, 1214, 1202, 1183, 1162, 1130, 1082, 1036, 998, 970, 958, 913, 882, 815, 790, 745, 716, 682, 641, 601, 590, 562, 545, 511, 494, 465cm -1 MALDI TOF-MS: POSITIVE M + 407(C 26 H 28 FOS + equivalent) NEGATIVE M - 651(C 37 H 47 O6S2 - equivalent)

[0352] [Example I-5] Synthesis of PAG-5 [ka]

[0353] PAG-5 was synthesized in the same manner as in Example I-3, except that intermediate In-2 was replaced with intermediate In-6 (yield 10.3g, yield 92%).

[0354] The IR spectral data and TOF-MS results for PAG-5 are shown below. Also, the nuclear magnetic resonance spectrum ( 1 The results of 1H-NMR / DMSO-d6 are shown in Figure 5. IR(D-ATR): ν= 3452, 3060, 2988, 2871, 1749, 1599, 1569, 1498, 1477, 1446, 1397, 1365, 1325, 1267, 1252, 1214, 1175, 1143, 1123, 1092, 1038, 1000, 968, 953, 912, 870, 808, 749, 717, 685, 656, 640, 617, 591, 560, 527, 504 cm -1 MALDI TOF-MS: POSITIVE M + 407(C 26 H 28 FOS + equivalent) NEGATIVE M - 711(C 17 H 14 I3O5S - equivalent)

[0355] [Examples I-6 to I-17] Synthesis of PAG-6 to PAG-17 Various onium salts were synthesized using corresponding raw materials and various organic synthesis reactions. The structures of the onium salts used in the chemically amplified resist compositions are shown below.

[0356] [ka]

[0357] [2] Synthesis of base polymers The base polymer used in the chemically amplified resist composition was synthesized by the method described below. The Mw and Mn of the obtained polymer were measured as polystyrene equivalent values ​​by GPC using THF as the solvent.

[0358] [Synthesis Example] Synthesis of base polymers (polymers P-1 to P-6) Each monomer was combined and copolymerized in THF, a solvent. The reaction solution was added to methanol, and the precipitated solid was washed with hexane, then isolated and dried to obtain base polymers (polymers P-1 to P-6) 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).

[0359] [ka]

[0360] [3] Preparation of chemically amplified resist compositions [Examples 1-1 to 1-32, Comparative Examples 1-1 to 1-24] Chemically amplified resist compositions (R-1 to R-32, CR-1 to CR-24) were prepared by dissolving the sulfonium salts (photoacid generators: PAG-1 to PAG-17), comparative photoacid generators (PAG-A to PAG-L), base polymers (P-1 to P-6), quenchers (Q-1 to Q-6), and hydrophobic resin F-1 in the compositions shown in Tables 1 and 2 below, in a solvent containing 100 ppm of FC-4430 manufactured by 3M as a surfactant, and filtering the solution through a 0.2 μm Teflon® type filter.

[0361] [Table 1]

[0362] [Table 2]

[0363] In Tables 1 and 2, the solvent, hydrophobic resin F-1, comparative photoacid generators PAG-A to PAG-L, and quenchers Q-1 to Q-6 are as follows: • Solvent: PGMEA (Propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol) EL (Ethyl Lactate) PGME (Propylene Glycol Monomethyl Ether)

[0364] • Hydrophobic resin: F-1 [ka]

[0365] • Comparative photoacid generators: PAG-A~PAG-L [ka]

[0366] • Quencher: Q-1~Q-6 [ka]

[0367] [4] EUV lithography evaluation (1) [Examples 2-1 to 2-15, Comparative Examples 2-1 to 2-12] Each chemically amplified resist composition (R-1 to R-15, CR-1 to CR-12) shown in Tables 1 and 2 was spin-coated onto a Si substrate formed with a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. to a thickness of 20 nm. A 50 nm thick resist film was then fabricated by pre-baking at 100°C for 60 seconds using a hot plate. This film was then exposed to an LS pattern with a wafer dimension of 18 nm and a pitch of 36 nm using an ASML EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, dipole illumination) by varying the exposure dose and focus (exposure dose pitch: 1 mJ / cm²). 2 The process was carried out while adjusting the focus pitch (0.020 μm), and after exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 3 and 4. Then, paddle development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution, rinsed with a surfactant-containing rinse material, and spin-dried to obtain a positive type pattern. The obtained LS patterns were observed using a Hitachi High-Technologies Corporation measuring SEM (CG6300), and sensitivity, exposure margin (EL), LWR, depth of field (DOF), and tilt limit were evaluated according to the method described below. The results are shown in Tables 3 and 4.

[0368] [Sensitivity evaluation] Optimal exposure amount E for obtaining an LS pattern with a line width of 18 nm and a pitch of 36 nm op (mJ / cm 2 The value of ) was calculated and defined as the sensitivity. The smaller this value, the higher the sensitivity.

[0369] [EL rating] The exposure amount formed within ±10% (16.2 to 19.8 nm) of the 18 nm space width in the aforementioned LS pattern was used to calculate the EL (unit: %) using the following formula. A larger value indicates better performance. EL(%)=(|E1-E2| / E op ) × 100 E1: Optimal exposure amount to give an LS pattern with a line width of 16.2 nm and a pitch of 36 nm. E2: Optimal exposure amount to give an LS pattern with a line width of 19.8 nm and a pitch of 36 nm. E op : Optimal exposure amount to give an LS pattern with a line width of 18nm and a pitch of 36nm

[0370] [LWR rating] E op The LS pattern obtained by irradiation was measured at 10 points along the longitudinal direction of the line, and the LWR was calculated as three times the standard deviation (σ) (3σ) from the results. The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0371] [DOF rating] To evaluate the depth of focus, the focus range formed within ±10% of the 18nm dimension (16.2 to 19.8nm) in the aforementioned LS pattern was determined. A larger value indicates a wider depth of focus.

[0372] [Evaluation of the limit of line pattern collapse] The line dimensions for each exposure amount at the optimal focus of the aforementioned LS pattern were measured at 10 points along the longitudinal direction. The thinnest line dimension obtained without collapse was defined as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0373] [Table 3]

[0374] [Table 4]

[0375] The results shown in Tables 3 and 4 indicate that the chemically amplified resist composition containing the photoacid generator of the present invention exhibits excellent EL, LWR, and DOF with good sensitivity. Furthermore, it was confirmed that the tilt limit value is small and that the pattern is resistant to tilting even in the formation of fine patterns. Therefore, the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[0376] [5] EUV Lithography Evaluation (2) [Examples 3-1 to 3-15, Comparative Examples 3-1 to 3-12] Each chemically amplified resist composition (R-1 to R-15, CR-1 to CR-12) 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. The resist film was then pre-baked at 105°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. This was then exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, wafer-mounted dimensions of 46 nm pitch, +20% bias hole pattern mask), and PEB was performed for 60 seconds at the temperatures listed in Tables 5 and 6 using a hot plate. Development was then performed with a 2.38% by mass TMAH aqueous solution for 30 seconds to form a hole pattern with dimensions of 23 nm. Using a Hitachi High-Technologies Corporation length-measuring SEM (CG6300), the exposure amount when a hole dimension of 23 nm was formed was measured and defined as the sensitivity. The dimensions of 50 holes at that time were also measured, and the dimensional variation (CDU) was defined as three times the standard deviation (σ) calculated from the results (3σ). The results are shown in Tables 5 and 6.

[0377] [Table 5]

[0378] [Table 6]

[0379] The results shown in Tables 5 and 6 confirm that the chemically amplified resist composition of the present invention exhibits good sensitivity and excellent CDU.

[0380] [6] EB lithography evaluation [Examples 4-1 to 4-17, Comparative Examples 4-1 to 4-12] Each chemically amplified positive resist composition (R-16 to R-32, CR-13 to CR-24) was spin-coated onto a 152 mm square photomask blank with a chromium outer surface using ACT-M (manufactured by Tokyo Electron Limited), and then pre-baked on a hot plate at 110°C for 600 seconds to produce a resist film with a thickness of 80 nm.

[0381] Furthermore, exposure was performed using an electron beam lithography system (EBM-5000plus, manufactured by Newflare Technology Co., Ltd., accelerating voltage 50kV), followed by PEB at 110°C for 600 seconds, and development with a 2.38 mass% TMAH aqueous solution to obtain a positive-type pattern.

[0382] The obtained resist patterns were evaluated as follows: The fabricated patterned mask blanks were observed using an overhead SEM (scanning electron microscope), and the optimal exposure (μC / cm²) was determined to resolve 200 nm 1:1 line and space (LS) lines at a 1:1 ratio. 2The resolution (limiting resolution) was defined as the minimum dimension at the exposure dose that resolves a 200nm LS at a 1:1 ratio, and the LER of a 200nm LS was measured by SEM. For development loading evaluation (variability), the exposure dose (μC / cm²) that resolves a 200nm LS at a 1:1 ratio within the substrate surface was defined. 2 The dimensions of the space between a 200nm LS pattern formed using ( ) and a 200nm LS pattern with dummy patterns of densities of 15%, 25%, 33%, 45%, 50%, 55%, 66%, 75%, 85%, and 95% placed around the pattern were measured by SEM, and the difference in dimensional differences between the dense and sparse patterns was compared. The pattern shape was determined visually to determine whether it was rectangular or not.

[0383] The overexposure dissolution rate is determined by spin-coating a resist solution onto an 8-inch silicon wafer, baking it at 110°C for 60 seconds to form a 90 nm thick resist film, and then applying an exposure dose (mJ / cm²) that resolves a 200 nm 1:1 line-and-space (LS) pattern at a 1:1 ratio. 2 Exposure was performed with KrF excimer laser light, followed by baking at 110°C for 60 seconds. Then, the resist was developed at 23°C using a 2.38 mass% TMAH aqueous solution with a resist development analyzer (RDA-800, manufactured by Lithotec Japan Co., Ltd.) and calculated. The results are shown in Tables 7 and 8.

[0384] [Table 7]

[0385] [Table 8]

[0386] As shown in Tables 7 and 8, the chemically amplified resist compositions containing the photoacid generator of the present invention all exhibited good resolution, LER, and pattern rectangularity, and showed suppressed development loading. Therefore, the chemically amplified resist compositions of the present invention are also suitable as materials for EB lithography.

[0387] This specification includes the following embodiments: [1]: A sulfonium salt represented by the following formula (1). [ka] (In the formula, p is an integer from 1 to 3. R 11 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Furthermore, two of the three substituents bonded to the sulfonium cation may bond to each other, forming a ring with the sulfur atom to which they are bonded. f represents a fluorine atom, a fluorine-containing alkyl group with 1 to 6 carbon atoms, an alkoxy group, or a sulfide group. q represents an integer from 1 to 4, and if q ≥ 2, R f They may be the same or different from each other. ALU R represents an acid-unstable group formed with adjacent oxygen atoms. r is an integer from 1 to 4. 12 is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. s is an integer from 0 to 4. t represents an integer from 0 to 2. When t=0, q+r+s≦5; when t=1, q+r+s≦7; and when t=2, q+r+s≦9. R f and -OR ALU X is bonded to adjacent carbon atoms. - (This represents a non-nucleophilic counterion that does not contain polymerizable groups.) [2]: In formula (1) above, R ALU The sulfonium salt according to [1], characterized in that the compound is represented by the following formula (ALU-1) or (ALU-2). [ka] (In formula (ALU-1), R 21 , R 22 , and R 23 Each of these is independently a substituted hydrocarbyl group having 1 to 10 carbon atoms. Also, R 21 , R 22 , and R 23 Any two of these may be joined together to form a ring. u is an integer of 0 or 1. In equation (ALU-2), R 24 , and R25 Each of these is independently a hydrogen atom or a substituted, carbon-1 to carbon-10 hydrocarbyl group. 26 is a hydrocarbyl group having 1 to 20 carbon atoms, or R 24 , or R 25 They bond with each other, and the carbon atoms and X that they bond to. a Together with the above, a heterocyclic group having 3 to 20 carbon atoms may be formed. Furthermore, the -CH2- contained in the hydrocarbyl group and the heterocyclic group may be replaced with -O- or -S-. a represents an oxygen atom or a sulfur atom. v is an integer, either 0 or 1. * represents a bond with an adjacent oxygen atom. [3]: In equation (1) above, X - The sulfonium salt according to [1] or [2], characterized in that the non-nucleophilic counterion that does not contain polymerizable groups is a sulfonate anion, an imidoate anion, or a methidoate anion. [4]: A photoacid generator comprising a sulfonium salt described in any of [1] to [3]. A resist composition characterized by containing the photoacid generator described in [5]:[4]. [6]: The resist composition according to [5], characterized in that it comprises a base resin having repeating units represented by the following formula (a1) or (a2). [ka] (In the formula, R A These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. A This refers to a single bond, a phenylene group, a naphthylene group, or (main chain)-C(=O)-OZ A1 - and Z A1 This is a linear, branched, or cyclic alkanediyl group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. B The bond is either a single bond or (main chain)-C(=O)-O-. A and X B These are, independently, acid-unstable groups. B(where n is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. n is an integer from 0 to 4.) [7]: The resist composition according to [6], characterized in that the base resin further comprises repeating units represented by the following formula (b1) or (b2). [ka] (In the formula, R A , Z B This is the same as above. Y A R is a polar group comprising a hydrogen atom, or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a sulfonic acid amide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic acid anhydride. b (m is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. m represents an integer from 1 to 4.) [8]: The resist composition according to [6] or [7], further characterized in that the base resin contains at least one repeating unit selected from repeating units represented by the following formulas (c1) to (c4). [ka] (In the formula, R A This is the same as above. Z 1 This is a single bond or a phenylene group. 2 This is a single bond, *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or *-OZ 21 - is Z 21 This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 - is Z31 This is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. 4 This refers to a single bond, a methylene group, or *-Z 41 -C(=O)-O- Z 41 This is a C1-C20 hydrocarbylene group which may contain heteroatoms, ether bonds, or ester bonds. 5 This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-OZ. 51 -, *-C(=O)-N(H)-Z 51 -or *-OZ 51 - is Z 51 This is a phenylene group substituted with an aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, or trifluoromethyl group having 1 to 6 carbon atoms, and may also contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * represents a bond with a carbon atom in the main chain or a group on the main chain side. R 21 and R 22 These may bond with each other to form a ring with the sulfur atom to which they are bonded. 1 These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Rf 1 and Rf 2 Each of these is independently a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. However, all Rf 5 and Rf 6 They cannot become hydrogen atoms at the same time. - A is a non-nucleophilic counterion. + c is an onium cation. c is an integer between 0 and 3. [9]: The resist composition according to any one of [6] to [8], further characterized by containing an organic solvent.

[10] : The resist composition according to any one of [6] to [9], further characterized by containing a compound represented by the following formula (5) or (6). [ka] (In the formula, R q1 This refers to a monovalent hydrocarbon group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. q2 This is a monovalent hydrocarbon group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom. + (This is an onium cation.)

[11] : The resist composition according to any one of [6] to

[10] , further characterized in that it contains other photoacid generators in addition to the photoacid generator described in [4].

[12] : The resist composition according to any one of [6] to

[11] , further characterized by containing an amine compound.

[13] : The resist composition according to any one of [6] to

[12] , further comprising a surfactant that is insoluble or sparingly soluble in water and soluble in an alkaline developer, and / or a surfactant that is insoluble or sparingly soluble in water and an alkaline developer.

[14] : A pattern forming method comprising the steps of forming a resist film on a substrate using a resist composition described in any one of [6] to

[13] , exposing the resist film with a high-energy beam, and developing the exposed resist film using a developer.

[15] : The pattern formation method according to

[14] , characterized in that the high-energy beam is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0388] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A sulfonium salt represented by the following formula (1). 【Chemistry 1】 (In the formula, p is an integer from 1 to 3. R １１ This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. Furthermore, two of the three substituents bonded to the sulfonium cation may bond to each other, forming a ring with the sulfur atom to which they are bonded. ｆ represents a fluorine atom, a fluorine-containing alkyl group with 1 to 6 carbon atoms, an alkoxy group, or a sulfide group. q represents an integer from 1 to 4, and if q ≥ 2, R ｆ They may be the same or different from each other. ＡＬＵ R represents an acid-unstable group formed with adjacent oxygen atoms. r is an integer from 1 to 4. １２ R is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. s is an integer from 0 to 4. t represents an integer from 0 to 2. When t = 0, q + r + s ≤ 5; when t = 1, q + r + s ≤ 7; and when t = 2, q + r + s ≤ 9. ｆ to-or-r ＡＬＵ X is bonded to adjacent carbon atoms. － (This represents a non-nucleophilic counterion that does not contain polymerizable groups.)

2. In the formula (1), R ＡＬＵ The sulfonium salt according to claim 1, wherein is represented by the following formula (ALU-1) or (ALU-2). 【Chemistry 2】 (In formula (ALU-1), R ２１ , R ２２ , and R ２３ Each of these is independently a substituted hydrocarbyl group having 1 to 10 carbon atoms. Also, R ２１ , R ２２ , and R ２３ Any two of these may be joined together to form a ring. u is an integer of 0 or 1. In equation (ALU-2), R ２４ , and R ２５ Each of these is independently a hydrogen atom or a substituted, carbon-1 to carbon-10 hydrocarbyl group. ２６ is a hydrocarbyl group having 1 to 20 carbon atoms, or R ２４ , or R ２５ They bond to each other, and the carbon atoms and X that they bond to ａ Together with the above, a heterocyclic group having 3 to 20 carbon atoms may be formed. Furthermore, the -CH contained in the hydrocarbyl group and the heterocyclic group may also be present. ２ The dash (-) may be replaced with -O- or -S-. ａ represents an oxygen atom or a sulfur atom. v is an integer of 0 or 1. * represents a bond with an adjacent oxygen atom.

3. In the above formula (1), X － The sulfonium salt according to claim 1, characterized in that the non-nucleophilic counterion that does not contain polymerizable groups is a sulfonate anion, an imidoate anion, or a methidoate anion.

4. In the above formula (1), X － The sulfonium salt according to claim 2, characterized in that the non-nucleophilic counterion that does not contain polymerizable groups is a sulfonate anion, an imidoate anion, or a methidoate anion.

5. A photoacid generator comprising a sulfonium salt according to any one of claims 1 to 4.

6. A resist composition characterized by containing the photoacid generator described in claim 5.

7. The resist composition according to claim 6, characterized in that it comprises a base resin having repeating units represented by the following formula (a1) or (a2). 【Transformation 3】 (In the formula, R Ａ These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ This is a single bond, a phenylene group, a naphthylene group, or (main chain)-C(=O)-O-Z Ａ１ - and Z Ａ１ This is a linear, branched, or cyclic alkanediyl group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. Ｂ The bond is either a single bond or (main chain)-C(=O)-O-. Ａ and X Ｂ These are, independently, acid-unstable groups. Ｂ (where n is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. n is an integer from 0 to 4.)

8. The resist composition according to claim 7, characterized in that the base resin further comprises repeating units represented by the following formula (b1) or (b2). 【Chemistry 4】 (In the formula, R Ａ Z Ｂ This is the same as above. Y Ａ R is a polar group comprising a hydrogen atom, or at least one structure selected from a hydroxyl group other than a phenolic hydroxyl group, a cyano group, a carbonyl group, a carboxyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a sulfonic acid amide bond, a carbonate bond, a lactone ring, a sultone ring, a sulfur atom, and a carboxylic acid anhydride. ｂ (m is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain heteroatoms. m represents an integer from 1 to 4.)

9. Furthermore, the resist composition according to claim 7 is characterized in that the base resin contains at least one repeating unit selected from repeating units represented by the following formulas (c1) to (c4). 【Transformation 5】 (In the formula, R Ａ This is the same as above. Z １ This is a single bond or a phenylene group. ２ This is a single bond, *-C(=O)-O-Z ２１ -, *-C(=O)-NH-Z ２１ - or * - O - Z ２１ - is Z ２１ This is a divalent group obtained by combining an aliphatic hydrocarbylene group, a phenylene group, or a combination thereof, having 1 to 6 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. ３ This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-Z ３１ - is Z ３１ This is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. ４ This refers to a single bond, a methylene group, or *-Z. ４１ -C(=O)-O-. Z ４１ This is a hydroxylene group having 1 to 20 carbon atoms, which may contain heteroatoms, ether bonds, or ester bonds. ５ This includes single bonds, methylene groups, ethylene groups, phenylene groups, fluorinated phenylene groups, trifluoromethyl groups, and *-C(=O)-O-Z. ５１ -, *-C(=O)-N(H)-Z ５１ - or * - O - Z ５１ - is Z ５１ This is a phenylene group substituted with an aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, or trifluoromethyl group having 1 to 6 carbon atoms, and may also contain a carbonyl group, ester bond, ether bond, or hydroxyl group. * indicates a bond with a carbon atom in the main chain or a group on the main chain side. R ２１ and R ２２ These may bond with each other to form a ring with the sulfur atom to which they are bonded. １ These are single bonds, ether bonds, ester bonds, carbonyl groups, sulfonic acid ester bonds, carbonate bonds, or carbamate bonds. Rf １ and Rf ２ Each of these is independently a fluorine atom or a fluorinated alkyl group having 1 to 6 carbon atoms. Rf ３ and Rf ４ Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. Rf ５ and Rf ６ Each of these is independently a hydrogen atom, a fluorine atom, or a fluorinated alkyl group having 1 to 6 carbon atoms. However, all Rf ５ and Rf ６ They cannot simultaneously become hydrogen atoms. M － A is a non-nucleophilic counterion. ＋ c is an onium cation. c is an integer between 0 and 3.

10. Furthermore, the resist composition according to claim 6, characterized in that it contains an organic solvent.

11. Furthermore, the resist composition according to claim 6 is characterized by containing a compound represented by the following formula (5) or (6). 【Transformation 6】 (In the formula, R ｑ１ This refers to a monovalent hydrocarbon group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. ｑ２ This is a monovalent hydrocarbon group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom. Mq ＋ This is an onium cation.

12. Furthermore, the resist composition according to claim 6 is characterized in that it contains other photoacid generators in addition to the photoacid generator described in claim 5.

13. Furthermore, the resist composition according to claim 6, characterized in that it further contains an amine compound.

14. Furthermore, the resist composition according to claim 6 is characterized by containing a surfactant that is insoluble or sparingly soluble in water and soluble in an alkaline developer, and / or a surfactant that is insoluble or sparingly soluble in water and an alkaline developer.

15. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist composition described in claim 6; 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, characterized in that the high-energy beam is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

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