Sulfonium salt, acid generator, resist composition and method for producing device

Abstract

To provide a resist composition with superior lithographic performance such as sensitivity and LWR, and also provide a sulfonium salt applicable as an acid generator in the resist composition, and an acid generator comprising the sulfonium salt.SOLUTION: The present invention provides a sulfonium salt represented by the general formula (1) where R1 is a hydrogen atom, a hydroxyl group, a carboxyl group, an electron-withdrawing group, an amino group, an optionally substituted C1-30 linear, branched-chain or cyclic alkyl group, a C2-30 linear, branched-chain or cyclic alkenyl group or the like; Ar is a C6-14 aryl group or a C3-20 heteroaryl group; the sulfonium salt in the formula has at least one iodine atom in the sulfonium cation structure; and X- is a monovalent anion.SELECTED DRAWING: None

Description

[Technical field]

[0001] Some aspects of the present invention relate to a chemically amplified resist composition and a method for manufacturing a device using the same. Also, some aspects of the present invention relate to a sulfonium salt useful as an acid generator for a chemically amplified resist composition, and an acid generator that decomposes upon irradiation with active energy rays to generate an acid. [Background technology]

[0002] In semiconductor devices, such as highly integrated circuit elements typified by DRAMs, there is a strong demand for higher density, higher integration, and higher speed. Accordingly, in the field of electronic device manufacturing, the demand for the establishment of microfabrication technology on the order of half microns, for example, the development of photolithography technology for forming fine patterns, is becoming increasingly strict. In order to form fine patterns in photolithography technology, it is necessary to improve the resolution. Here, the resolution (R) of a reduced projection exposure tool is expressed by the Rayleigh equation R=k·λ / NA (where λ is the wavelength of the active energy ray, NA is the numerical aperture of the lens, and k is the process factor). The resolution can be improved by shortening the wavelength λ of the active energy ray used in forming the resist pattern. As short-wavelength active energy rays, there is a tendency to use KrF excimer laser (248 nm), ArF excimer laser (193 nm), EUV (extreme ultraviolet, 13.5 nm) and electron beams. Lithography techniques using these active energy rays, particularly EUV or electron beams, allow for fine processing with single patterning. Therefore, it is considered that the need for resist compositions that are highly sensitive to EUV or electron beams will further increase in the future.

[0003] As exposure light sources become shorter in wavelength, resist compositions are required to have improved properties such as high sensitivity to the exposure light source and the ability to reproduce fine dimensional patterns. Chemically amplified photoresists have been proposed as resist compositions that satisfy such requirements. The characteristic of chemically amplified photoresists is that an acid is generated from an acid generator, which is a component, when irradiated with active energy rays, and this acid causes an acid catalysis reaction when heated after exposure (Patent Document 1).

[0004] As an acid generator used in a chemically amplified photoresist, a sulfonium salt having a 1-phenylbenzo[b]thiophenium skeleton is known (Patent Document 2). However, resist compositions using sulfonium salts having the above skeleton have not provided sufficiently satisfactory results in terms of lithography performance such as sensitivity and LWR. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-287174 [Patent Document 2] JP 2008-33016 A Summary of the Invention [Problem to be solved by the invention]

[0006] In view of these circumstances, some aspects of the present invention have the objective of providing a resist composition that is excellent in lithography performance such as sensitivity and LWR, etc. Another objective is to provide a sulfonium salt that can be used as an acid generator for the resist composition, and an acid generator comprising the sulfonium salt. [Means for solving the problem]

[0007] As a result of intensive investigations aimed at solving the above problems, the present inventors discovered that by using a sulfonium salt having a specific structure as an acid generator in a resist composition, the resist composition has high sensitivity, and also has excellent lithography properties such as sensitivity and LWR. This discovery has led to the completion of several aspects of the present invention.

[0008] One embodiment of the present invention that solves the above problems is a sulfonium salt represented by the following general formula (1). [ka]

[0009] In the above general formula (1), R 1 is any one selected from the group consisting of a hydrogen atom; a hydroxyl group; a carboxyl group; an electron-withdrawing group; an amino group which may have a substituent; a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenyl group having 2 to 30 carbon atoms which may have a substituent; an aryl group having 5 to 30 carbon atoms which may have a substituent; and a heteroaryl group having 3 to 30 carbon atoms which may have a substituent; Ar is an aryl group having 6 to 14 carbon atoms which may have a substituent or a heteroaryl group having 3 to 20 carbon atoms which may have a substituent, and R 1 If there are two or more, two R 1 may form a ring directly via a single bond or via any divalent group selected from the group consisting of oxygen atoms, sulfur atoms, and nitrogen atom-containing groups, n is an integer of 1 to 3, and when n is 1, m is an integer of 0 to 6, when n is 2, m is an integer of 0 to 8, and when n is 3, m is an integer of 0 to 10, and the sulfonium salt in the above general formula (1) has at least one iodine atom in the sulfonium cation structure, and X - is a monovalent anion.

[0010] Another embodiment of the present invention is an acid generator comprising the above sulfonium salt.

[0011] Another aspect of the present invention is a resist composition comprising the above-mentioned acid generator and an acid-reactive compound.

[0012] Another aspect of the present invention is a method for manufacturing a device, comprising the steps of forming a resist film on a substrate using the resist composition, exposing the resist film to active energy rays, and developing the exposed resist film.

[0013] Various aspects of the present invention will be described below. The following aspects can be combined with each other. [1] A sulfonium salt represented by the following formula (1): [ka] (In the above formula (1), R 1 is any one selected from the group consisting of a hydrogen atom; a hydroxyl group; a carboxyl group; an electron-withdrawing group; an amino group which may have a substituent; a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenyl group having 2 to 30 carbon atoms which may have a substituent; an aryl group having 5 to 30 carbon atoms which may have a substituent; and a heteroaryl group having 3 to 30 carbon atoms which may have a substituent; Ar is an optionally substituted aryl group having 6 to 14 carbon atoms or an optionally substituted heteroaryl group having 3 to 20 carbon atoms, R 1 If there are two or more, two R 1 may form a ring directly via a single bond or via any divalent group selected from the group consisting of oxygen atom-, sulfur atom-, and nitrogen atom-containing groups, n is an integer from 1 to 3; When n is 1, m is an integer from 0 to 6; When n is 2, m is an integer from 0 to 8; When n is 3, m is an integer from 0 to 10; The sulfonium salt in the above formula (1) has at least one iodine atom in the sulfonium cation structure, X - is a monovalent anion.) [2] The sulfonium salt according to [1], wherein Ar is an aryl group having 1 to 5 ring members or a heteroaryl group having 1 to 5 ring members. [3] The sulfonium salt according to [1] or [2], wherein the heteroatom of the heteroaryl group in Ar is any one selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. [4] When the Ar group has two or more substituents, the two substituents may be the same or different. The sulfonium salt according to any one of [1] to [3], wherein the two substituents may be bonded to each other directly via a single bond or via at least one selected from the group consisting of a divalent heteroatom-containing group and an alkylene group to form a ring structure. [5] The sulfonium salt according to any one of [1] to [4], wherein Ar in the above formula (1) is selected from the group consisting of a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, a benzofuryl group, an indole group, a thienyl group, a furyl group, a dibenzofuryl group, a carbazole group, a benzothienyl group, a dibenzothienyl group, an imidazole group, a pyridinyl group, a chromenyl group and a pyrrole group, each of which may have a substituent. [6] The sulfonium salt according to any one of [1] to [5], wherein the anion is at least one selected from the group consisting of a halogen anion, a hydroxide anion, a borane anion, a sulfate anion, a carbonate anion, a sulfonate anion, a carboxylate anion, an imide anion, and a methide anion. [7] The sulfonium salt according to [1], wherein the anion is represented by the following formula (2): [ka] (In the above formula (2), A - is a sulfonate or carboxylate anion, Q is any one selected from the group consisting of a hydrogen atom; a fluorine atom; and a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent; r is an integer from 0 to 3; Multiple Q may be the same or different, T is any one selected from the group consisting of a single bond; a linear, branched or cyclic alkylene group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenylene group having 2 to 30 carbon atoms which may have a substituent; an arylene group having 5 to 30 carbon atoms which may have a substituent; and a heteroarylene group having 3 to 30 carbon atoms which may have a substituent; At least one methylene group in T may be substituted with a divalent heteroatom-containing group; L is a single bond or a divalent heteroatom-containing group; Z is an organic group having 1 to 30 carbon atoms which may have a substituent. [8] An acid generator comprising the sulfonium salt according to any one of [1] to [7]. [9] A resist composition comprising the acid generator according to [8] and an acid-reactive compound.

[10] The resist composition according to [9], further comprising an acid diffusion controller.

[11] The resist composition according to [9] or

[10] , further comprising a water-repellent polymer.

[12] forming a resist film on a substrate using the resist composition according to any one of [9] to

[11] ; exposing the resist film to active energy rays; and developing the exposed resist film.

[13] The method for manufacturing a device according to

[12] , wherein the active energy rays are extreme ultraviolet rays or electron beams. Effect of the Invention

[0014] In one embodiment of the present invention, when an acid generator consisting of a sulfonium salt having a specific structure is used in a resist composition containing an acid-reactive compound and the acid generator, the resist composition tends to have high sensitivity and also to have excellent lithography properties such as sensitivity and LWR. Furthermore, when used as an acid generator in a resist composition, the sulfonium salt having a specific structure according to one embodiment of the present invention is useful as an acid generator that efficiently generates acid upon irradiation with active energy rays. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in detail below. <1> Sulfonium Salts R in the above general formula (1) 1 is any one selected from the group consisting of a hydrogen atom; a hydroxyl group; a carboxyl group; an electron-withdrawing group; an amino group which may have a substituent; a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenyl group having 2 to 30 carbon atoms which may have a substituent; an aryl group having 5 to 30 carbon atoms which may have a substituent; and a heteroaryl group having 3 to 30 carbon atoms which may have a substituent.

[0016] Above R 1 At least one methylene group therein may be substituted with a divalent heteroatom-containing group. R 1 The above amino group, alkyl group, alkenyl group, aryl group and heteroaryl group as may have a substituent (hereinafter also referred to as a "first substituent").

[0017] The first substituent is an aryl group (Ar Sp ); A linear, branched or cyclic alkyl group (R Sp ); a linear or cyclic alkenyl group; the alkyl group (R Span alkyl group having a divalent heteroatom-containing group in its skeleton in place of at least one methylene group of the above alkenyl group; an alkenyl group having a divalent heteroatom-containing group in its skeleton in place of at least one methylene group of the above alkenyl group; an aryl group (Ar Sp ); a heteroaryl group which may contain a divalent heteroatom instead of a carbon atom in the ring structure of the aryl group; a hydroxyl group; a mercapto group; a carboxyl group; a cyano group; a formyl group; and a halogen atom. Examples of the halogen atom as the first substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The first substituent may be further substituted with a first substituent. When the first substituent has a further first substituent, these substituents may be the same or different within the above range of the first substituent.

[0018] In the present invention, the divalent heteroatom-containing group is -O-, -CO-, -COO-, -OCO-, -O-CO-O-, -NHCO-, -CONH-, -NH-CO-O-, -O-CO-NH-, -N(R Sp )-, -N(Ar Sp )-, -S-, -SO- and -SO 2 Among the divalent heteroatom-containing groups, -NHCO-, -CONH-, -NH-CO-O-, and -O-CO-NH- each independently represent a hydrogen atom, and R Sp Or Ar Sp may be substituted with

[0019] Above R 1 The number of carbon atoms of the amino group, alkyl group, alkenyl group, aryl group and heteroaryl group as mentioned above is preferably the total number of carbon atoms including the number of carbon atoms of the first substituent.

[0020] R 1Examples of the amino group which may have a substituent as the substituent include a methylamino group, an ethylamino group, an n-butylamino group, an isobutylamino group, a tert-butylamino group, a cyclohexylamino group, a phenylamino group, a 4-iodophenylamino group, a dimethylamino group, a diethylamino group, a di-n-butylamino group, a dicyclohexylamino group, a diphenylamino group, a di-4-iodophenylamino group, a methyl(phenyl)amino group, an ethyl(phenyl)amino group, a methyl(naphthyl)amino group, an isopropyl(phenyl)amino group, and a cyclohexyl(phenyl)amino group.

[0021] R 1 Examples of the alkyl group as the alkyl group include linear alkyl groups such as methyl, ethyl, n-propyl and n-butyl groups, branched alkyl groups such as isopropyl and t-butyl groups, and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl and norbornyl groups. In addition, the linear alkyl group may be an alkenyl group in which at least one carbon-carbon single bond is replaced with a carbon-carbon double bond.

[0022] R 1 Examples of the aryl group as the aryl group include monovalent monocyclic aromatic hydrocarbon groups such as a phenyl group; monovalent condensed polycyclic aromatic hydrocarbon groups such as a naphthyl group, anthryl group, phenanthrenyl group, pentalenyl group, indenyl group, indacenyl group, acenaphthyl group, fluorenyl group, heptalenyl group, naphthacenyl group, pyrenyl group, and chrysenyl group; and monovalent linked polycyclic aromatic hydrocarbon groups such as a biphenyl group, a terphenyl group, and a quaterphenyl group. The upper limit of the number of carbon atoms in the aryl group is preferably 20, and more preferably 10.

[0023] R 1Examples of the heteroaryl group as the heteroaryl group include monocyclic aromatic heterocyclic groups such as a furyl group, a thienyl group, a pyrrole group, an imidazole group, a pyrazole group, an oxazole group, a pyridinyl group, a pyrimidine group, and a pyrazine group; condensed polycyclic aromatic heterocyclic groups such as an indole group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a chromenyl group, a thianthrenyl group, a dibenzothienyl group, a phenothiazinyl group, a phenoxazinyl group, a xanthenyl group, an acridinyl group, a phenazinyl group, and a carbazole group; and linked polycyclic aromatic heterocyclic groups such as a 4-phenylpyridinyl group, a 9-phenylacridinyl group, and a bathophenanthrolinyl group. The upper limit of the number of carbon atoms in the heteroaryl group is preferably 20, and more preferably 10.

[0024] R 1 If there are two or more, two R 1 They may form a ring directly via a single bond or via any divalent group selected from the group consisting of a divalent heteroatom-containing group and an alkylene group.

[0025] R 1 Examples of the electron-withdrawing group as include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a trifluoromethyl group, and a nitro group. An iodine atom is more preferable.

[0026] Ar is an aryl group having 6 to 14 carbon atoms which may have a substituent, or a heteroaryl group having 3 to 20 carbon atoms which may have a substituent.

[0027] The aryl group and heteroaryl group as Ar may have a substituent (hereinafter also referred to as a "second substituent"). The number of carbon atoms of the aryl group and heteroaryl group as Ar is preferably the total number of carbon atoms including the second substituent. The second substituent may be the same as the first substituent. When the second substituent further has a second substituent, these substituents may be the same or different within the range of the second substituent.

[0028] The aryl group represented by Ar preferably has 1 to 5 ring members, and more preferably 1 to 3 ring members.

[0029] The heteroaryl group represented by Ar preferably has 1 to 5 ring members, and more preferably has 1 to 3 ring members.

[0030] The heteroatom of the heteroaryl group in Ar is preferably a nitrogen atom, an oxygen atom, a sulfur atom, or the like.

[0031] When the above Ar may have two or more substituents, the two substituents may be the same or different. The two substituents may be bonded to each other directly via a single bond or via at least one selected from the group consisting of a divalent heteroatom-containing group and an alkylene group to form a ring structure.

[0032] Examples of the aryl group represented by Ar include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, and a pyrenyl group.

[0033] Preferred examples of the heteroaryl group represented by Ar include a furyl group, a thienyl group, a benzothienyl group, a benzofuryl group, a dibenzofuryl group, a pyrrole group, an imidazole group, a pyridinyl group, a chromenyl group, an indole group, and a dibenzothienyl group.

[0034] n is an integer from 1 to 3. When n is 1, m is an integer from 0 to 6. When n is 2, m is an integer from 0 to 8. When n is 3, m is an integer from 0 to 10.

[0035] The sulfonium salt in the above general formula (1) has at least one iodine atom in the sulfonium cation structure from the viewpoint of increasing sensitivity to EUV and electron beams, and from the viewpoint of solubility in a solvent in a resist composition, the number of iodine atoms in the sulfonium cation structure is preferably 7 or less, more preferably 3 or less, and even more preferably 2 or less.

[0036] Specific examples of the sulfonium cation structure represented by the above general formula (1) include the following compound groups. [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] X - is a monovalent anion. Preferred examples of the monovalent anion include a halogen anion, a hydroxide anion, a borane anion, a sulfate anion, a carbonate anion, a sulfonate anion, a carboxylate anion, an imide anion, and a methide anion. More preferred examples include a sulfonate anion and a carboxylate anion.

[0041] The sulfonate anion and carboxylate anion are preferably anions represented by the above general formula (2).

[0042] In the above general formula (2), A - is preferably a sulfonate anion or a carboxylate anion. Preferred examples of Q include a hydrogen atom; a fluorine atom; and a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent. The alkyl group represented by Q may have a substituent (hereinafter also referred to as a "third substituent"). The third substituent may be the same as the first substituent. When the third substituent further has a third substituent, these substituents may be the same or different within the range of the third substituent. Examples of the alkyl group as Q include linear alkyl groups such as methyl, ethyl, n-propyl, and n-butyl groups; branched alkyl groups such as isopropyl and t-butyl groups; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl groups. The number of carbon atoms in the alkyl group represented by Q is preferably the total number of carbon atoms including the number of the third substituent. Multiple Q's may be the same or different.

[0043] Preferred examples of Q include a hydrogen atom, a fluorine atom, and a trifluoromethyl group.

[0044] r is an integer from 0 to 3. - When A is a sulfonate anion, 1 to 3 are more preferable. - When is a carboxylate anion, it is preferably 0 to 2.

[0045] Preferred examples of T include a single bond; a linear, branched or cyclic alkylene group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenylene group having 2 to 30 carbon atoms which may have a substituent; an arylene group having 5 to 30 carbon atoms which may have a substituent; and a heteroarylene group having 3 to 30 carbon atoms which may have a substituent. At least one methylene group in the above T may be substituted with a divalent heteroatom-containing group.

[0046] L is a single bond or a divalent heteroatom-containing group.

[0047] Z is an organic group having 1 to 30 carbon atoms which may have a substituent. The organic group having 1 to 30 carbon atoms represented by Z may have a substituent (hereinafter referred to as a "fourth substituent"). The fourth substituent may be the same as the first substituent. When the fourth substituent further has a fourth substituent, these substituents may be the same or different within the range of the fourth substituent options. The number of carbon atoms in the organic group represented by Z is preferably the total number of carbon atoms including the number of carbon atoms in the fourth substituent.

[0048] Examples of the organic group represented by Z include a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent (fourth substituent); a linear, branched or cyclic alkenyl group having 2 to 30 carbon atoms which may have a substituent (fourth substituent); an aryl group having 5 to 30 carbon atoms which may have a substituent (fourth substituent); and a heteroaryl group having 3 to 30 carbon atoms which may have a substituent (fourth substituent).

[0049] Examples of the alkyl group as Z include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a tert-pentyl group, a 2-ethylhexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group. These alkyl groups may contain a divalent heteroatom-containing group instead of at least one methylene group. The divalent heteroatom-containing groups may be contained in appropriate combinations. These substituents may also be contained in a ring structure. However, it is preferable that the heteroatoms such as -OO-, -SS-, and -OS- are not continuously connected. At least one carbon-carbon single bond in the linear alkyl group may be replaced by a carbon-carbon double bond to form an alkenyl group.

[0050] Examples of the aryl group represented by Z include monovalent monocyclic aromatic hydrocarbon groups such as a phenyl group; monovalent condensed polycyclic aromatic hydrocarbon groups such as a naphthyl group, anthryl group, fluorenyl group, phenanthrenyl group, pentalenyl group, indenyl group, indacenyl group, acenaphthyl group, fluorenyl group, heptalenyl group, naphthacenyl group, pyrenyl group, and chrysenyl group; and monovalent linked polycyclic aromatic hydrocarbon groups such as a biphenyl group, a terphenyl group, and a quaterphenyl group. The upper limit of the number of carbon atoms in the aryl group is preferably 20, and more preferably 10.

[0051] Examples of the heteroaryl group represented by Z include monocyclic aromatic heterocyclic groups such as a furyl group, a thienyl group, a pyrrole group, an imidazole group, a pyrazole group, an oxazole group, a pyridinyl group, a pyrimidinyl group, and a pyrazinyl group; condensed polycyclic aromatic heterocyclic groups such as an indole group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a chromenyl group, a thianthrenyl group, a dibenzothienyl group, a phenothiazinyl group, a phenoxazinyl group, a xanthenyl group, an acridinyl group, a phenazinyl group, and a carbazole group; and linked polycyclic aromatic heterocyclic rings such as a 4-phenylpyridinyl group, a 9-phenylacridinyl group, and a phenylphenanthrolinyl group. The upper limit of the number of carbon atoms in the heteroaryl group is preferably 20, and more preferably 10.

[0052] Specific examples of the anion represented by the above general formula (2) include the following compound groups. [ka]

[0053] [ka]

[0054] The carboxylate anion, the imide anion and the methide anion include anions represented by the following general formulas (7) to (8), respectively. [ka] [ka]

[0055] In the above general formulas (7) to (8), R 13 ~R 17 are each independently the same as the monovalent organic group represented by the above general formula (2). 13 and R 14 , and R 15 ~R 17 Two of these may be bonded to each other to form a ring.

[0056] <2> Method for synthesizing sulfonium salts The sulfonium salt according to one embodiment of the present invention can be synthesized, for example, by the method described below. However, synthesis methods other than the route described below are also possible depending on the structure of the sulfonium salt.

[0057] In addition, R in the following synthesis examples 1 , X 1 , m and n are R in the above formula (1). 1 , X 1 , m and n. R in the following synthesis examples 2 corresponds to the second substituent in the above formula (1). + is preferably at least one selected from the group consisting of ammonium cations, alkali metal cations, alkaline earth metal cations, etc. p is preferably an integer of 0 to 5. q is preferably an integer of 0 to 3. G - isX - and is preferably at least one selected from the group consisting of carbonate anion, sulfonate anion, and the like. In addition, R in the synthesis examples 1 and R 2At least one of the above has an iodine atom.

[0058] [ka]

[0059] The benzothiophene represented by the above formula (a-1) and the iodonium salt represented by the above formula (a-2) are reacted with a copper catalyst to obtain the sulfonium salt represented by the above formula (a-3). The above reaction is preferably carried out in a solvent. M' + X - The salt represented by the formula (a-4) is obtained by salt exchange between the salt represented by the formula (a-3) and the salt represented by the formula (a-4).

[0060] [ka]

[0061] The benzothiophene represented by the above formula (b-1) and the iodonium salt represented by the above formula (b-2) are reacted with a copper catalyst to obtain the sulfonium salt represented by the above formula (b-3). The above reaction is preferably carried out in a solvent. M' + X - The salt represented by the formula (b-4) is obtained by salt exchange between the salt represented by the formula (b-3) and the salt represented by the formula (b-4).

[0062] <3> Acid Generator One embodiment of the present invention is an acid generator comprising a sulfonium salt represented by the above general formula (1). <4> Resist Composition One embodiment of the present invention is a resist composition comprising an acid generator (hereinafter also referred to as a "first acid generator") consisting of a sulfonium salt represented by the above general formula (1), and an acid-reactive compound.

[0063] The first acid generator is decomposed by exposure to active energy rays, and therefore a resist composition containing the first acid generator and an acid-reactive compound may be used as a photoresist.

[0064] Each component contained in the resist composition will now be described.

[0065] In addition, the resist composition according to one embodiment of the present invention may contain a second acid generator in addition to the first acid generator. When the resist composition contains an acid-reactive compound, if the acid generated from the second acid generator reacts with the acid-reactive compound and the acid generated from the first acid generator does not react with the acid-reactive compound, the first acid generator can act as a photodegradable base, which is one of the acid diffusion controllers. If the acid generated from the first acid generator reacts with the acid-reactive compound and the acid generated from the second acid generator does not react with the acid-reactive compound, the second acid generator can act as a photodegradable base, which is one of the acid diffusion controllers.

[0066] In addition, when the acids generated from the first acid generator and the second acid generator react with the acid-reactive compound, the first acid generator and the second acid generator can function as an acid generating agent.

[0067] When the first acid generator is contained in the resist composition as the photodegradable base, the photodegradable base decomposes in the exposed area, losing the acid diffusion controllability, and the secondary electrons generated by the decomposition act on the second acid generator, improving the acid generation from the second acid generator. On the other hand, in the unexposed area, the first acid generator as the photodegradable base is a salt having a conjugate base weaker than that of the second acid generator, so that it can deactivate the acid derived from the second acid generator by reacting with the acid generated from the second acid generator, and can act as an acid diffusion control agent. Therefore, when the first acid generator is used as the photodegradable base in the resist composition, it can be made into a resist composition having excellent characteristics of sensitivity and pattern forming ability.

[0068] The content of the first acid generator in the resist composition according to one embodiment of the present invention is preferably 0.5 to 75 parts by mass, more preferably 1 to 65 parts by mass, and even more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the acid-reactive compound described below.

[0069] When the resist composition contains the second acid generator in addition to the first acid generator, the total amount of the first acid generator and the second acid generator relative to the acid-reactive compound is preferably 1 to 90 parts by mass, and more preferably 5 to 80 parts by mass, per 100 parts by mass of the acid-reactive compound. The ratio of the first acid generator to the second acid generator in the resist composition varies depending on the application of the acid generation and the application of the acid diffusion controller, but is preferably from 30:1 to 1:30, and more preferably from 20:1 to 1:20.

[0070] Furthermore, when the resist composition contains the second acid generator in addition to the first acid generator, and the second acid generator is used as a photodegradable base, i.e., when the resist composition contains a second acid generator having a lower acid strength than the first acid generator, the content of the second acid generator in the resist composition is preferably 1 to 100 parts by mass, and more preferably 3 to 75 parts by mass, per 100 parts by mass of the first acid generator. By containing the first acid generator in the resist composition within the above range, it is possible to obtain excellent properties in terms of sensitivity and pattern forming ability.

[0071] Furthermore, when the resist composition contains the second acid generator in addition to the first acid generator, and the first acid generator is used as a photodegradable base, i.e., when the resist composition contains a second acid generator having a higher acid strength than the first acid generator, the content of the first acid generator in the resist composition is preferably 1 to 100 parts by mass, and more preferably 3 to 75 parts by mass, per 100 parts by mass of the second acid generator. By containing the first acid generator in the resist composition within the above range, it is possible to obtain excellent properties in terms of sensitivity and pattern formability. In calculating the content, the organic solvent is not included in the resist composition components. When the first acid generator and the second acid generator are bonded to a polymer, the mass is based on the mass excluding the polymer main chain.

[0072] <4-1> Second acid generator In some embodiments of the present invention, the resist composition preferably contains a second acid generator. Note that the second acid generator is an acid generator other than the first acid generator.

[0073] The second acid generator is not particularly limited as long as it is one that is used in a normal resist composition, and examples thereof include onium salts such as sulfonium salts and iodonium salts, N-sulfonyloxyimide compounds, oxime sulfonate compounds, organic halogen compounds, sulfonyldiazomethane compounds, etc. These may be used alone or in combination of two or more.

[0074] Examples of sulfonium salts include those described in WO2011 / 093139 and WO2021 / 095356. However, the present invention is not limited thereto.

[0075] As described above, it is preferable to use an anion in the second acid generator that has a higher acid strength than the anion in the onium salt of the first acid generator. More specifically, the second acid generator preferably has a pKa of −3 or less. Examples of such an anion include fluorine atom-substituted sulfonic acid.

[0076] When the second acid generator is used as the photodegradable base, the photodegradable base may be any of the photodegradable bases other than the onium salt of one embodiment of the present invention, which is photosensitive to light upon exposure and generates a weak acid.Specific examples of the photodegradable base include compounds described in Japanese Patent No. 3577743, JP-A No. 2001-215689, JP-A No. 2001-166476, JP-A No. 2008-102383, JP-A No. 2010-243773, JP-A No. 2011-37835, and JP-A No. 2012-173505.

[0077] The second acid generator may be contained in the resist composition as a low molecular weight component, or may be contained as a polymer unit. That is, the second acid generator may be included in the polymer as a unit so as to be bonded to the polymer main chain at any position of the second acid generator. For example, when the second acid generator is an onium salt, it is preferable that the onium salt has a bond bonded to the polymer main chain directly or via a linking group instead of one H of the cation or anion substituent in the onium salt.

[0078] <4-2> Acid-reactive compounds Examples of the acid-reactive compound include a compound having a protecting group that is deprotected by an acid, a compound having a polymerizable group that is polymerized by an acid, and a crosslinking agent that has a crosslinking action by an acid.

[0079] The compound having a protecting group that can be deprotected by an acid is a compound that generates a polar group by deprotecting the protecting group with an acid, and changes its solubility in a developer. For example, in the case of aqueous development using an alkaline developer or the like, the compound having a protecting group that can be deprotected by an acid is a compound that is insoluble in an alkaline developer, but becomes soluble in an alkaline developer by deprotecting the protecting group from the compound in an exposed area by the acid generated from the acid generator upon exposure.

[0080] In some embodiments of the present invention, the developer is not limited to an alkaline developer, and may be a neutral developer or an organic solvent developer. Therefore, when an organic solvent developer is used, the compound having a protecting group that can be deprotected by an acid is a compound in which the protecting group is deprotected from the compound by the acid generated from the acid generator upon exposure to generate a polar group in the exposed area, and the solubility in the organic solvent developer is reduced. Examples of the polar group of the acid-reactive compound include a hydroxyl group, a carboxyl group, an amino group, and a sulfo group.

[0081] The compound having a protecting group that can be deprotected by an acid may be a protecting group-containing low molecular weight compound or a protecting group-containing polymer. In some embodiments of the present invention, the low molecular weight compound has a weight average molecular weight of less than 2000, and the polymer has a weight average molecular weight of 2000 or more.

[0082] The above-mentioned compound having a protecting group that can be deprotected by an acid is represented by the following general formula (4). [ka]

[0083] In the above general formula (4), R 18 may be a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or the like. 1 and L 3 may be a single bond, an ether bond, an ester bond, etc. 2 Preferred examples of L include a single bond; a linear, branched or cyclic alkylene group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenylene group having 2 to 30 carbon atoms which may have a substituent; an arylene group having 5 to 30 carbon atoms which may have a substituent; and a heteroarylene group having 3 to 30 carbon atoms which may have a substituent. 2 At least one methylene group in R may be substituted with a divalent heteroatom-containing group. 19 ~R 21 may each independently be a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent. 19 ~R 21 These groups may be combined with each other to form a ring structure together with the carbon atoms to which they are attached.

[0084] The compound having a polymerizable group that is polymerized by acid is a compound that changes its solubility in a developer by being polymerized by acid.For example, in the case of aqueous development, it acts on a compound that is soluble in an aqueous developer, and reduces the solubility of the compound in an aqueous developer after polymerization.Specific examples include compounds having an epoxy group, a vinyloxy group, and an oxetanyl group. The compound having a polymerizable group that is polymerizable by an acid may be a polymerizable low molecular weight compound or a polymerizable polymer.

[0085] A crosslinking agent having a crosslinking action by an acid is a compound that changes the solubility in a developer by crosslinking with an acid. For example, in the case of aqueous development, it acts on a compound that is soluble in an aqueous developer, and reduces the solubility of the compound in an aqueous developer after polymerization or crosslinking. Specifically, crosslinking agents having an epoxy group, a vinyloxy group, a 1-alkoxyamino group, an oxetanyl group, etc. can be mentioned. When the compound is a crosslinking agent having a crosslinking action, a compound that reacts with the compound to be crosslinked, that is, the crosslinking agent, and changes the solubility in a developer can be a compound having a phenolic hydroxyl group, etc. The compound capable of crosslinking by an acid may be a polymerizable low molecular weight compound or a polymerizable polymer.

[0086] When the acid-reactive compound is a polymer, in addition to the unit to which the reactive compound is bonded, other units that are generally used in resist compositions may be contained in the polymer. Examples of the other units include a unit (I) having at least one selected from the group consisting of a lactone moiety, a sultone moiety, and a lactam moiety; a unit (II) having at least one selected from the group consisting of a group having an ether bond, an ester bond, an acetal structure, and a hydroxyl group; a hydroxyaryl group-containing unit (III); and the like. In addition, the polymer may contain a unit (IV) to which the sulfonium compound represented by the general formula (1) is bonded and a unit (V) to which an onium salt other than the sulfonium compound represented by the general formula (1) is bonded.

[0087] <4-3> Acid diffusion control agent The resist composition according to one embodiment of the present invention may contain an acid diffusion controller. The acid diffusion controller may be the first acid generator or the second acid generator described above, which is used as a photodegradable base. Furthermore, the acid diffusion controller may be a basic nitrogen-containing organic compound.

[0088] The acid diffusion controller controls the diffusion phenomenon of the acid generated from the acid generator in the resist film, and has the effect of controlling undesirable chemical reactions in the non-exposed region. Therefore, the storage stability of the resist composition obtained is further improved, and the pattern properties such as sensitivity and LWR as a resist are further improved, and the line width change of the resist pattern due to the fluctuation of the delay time from exposure to development processing can be suppressed, and a resist composition with excellent process stability can be obtained.

[0089] Examples of the basic nitrogen-containing organic compound include a compound having one nitrogen atom in the same molecule, a compound having two nitrogen atoms, a compound having three nitrogen atoms, an amide group-containing compound, a urea compound, a nitrogen-containing heterocyclic compound, and the like.

[0090] Examples of the nitrogen-containing organic compound include 1-naphthylamine, 2-naphthylamine, aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine, Amine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine, methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine , ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4'-diamino-1,2-diphenylethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 2,2'-methylenebisaniline, imidazo Examples of suitable aryl amines include aryl, 4-methylimidazole, pyridine, 4-methylpyridine, 1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane, 1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene, 1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane, di(2-pyridyl)ketone, 4,4'-dipyridyl sulfide, 4,4'-dipyridyl disulfide, 2,2'-dipyridylamine, 2,2'-dipicolylamine, and bipyridine.

[0091] When the acid diffusion controller is included, the content thereof is preferably 0.01 to 20 parts by mass, more preferably 0.03 to 15 parts by mass, and even more preferably 0.05 to 10 parts by mass, relative to 100 parts by mass of the acid reactive compound. The above content does not include the first acid generator of one embodiment of the present invention.

[0092] <4-4>Water repellent compound The resist composition according to one embodiment of the present invention may contain a water-repellent compound. The water-repellent compound is not particularly limited, but may be one that is commonly used in immersion lithography processes, and preferably has a fluorine atom content greater than that of the polymer. This allows the water-repellent compound to be unevenly distributed on the surface of the resist film when a resist film is formed using the resist composition due to the water repellency of the water-repellent compound.

[0093] Regarding the fluorine content of the water-repellent compound, it is preferable that 25% or more, and more preferably 50% or more, of the hydrogen atoms in the hydrocarbon groups in the water-repellent compound are fluorinated.

[0094] The content of the water-repellent compound in the resist composition is preferably 0.5 to 10 parts by mass per 100 parts by mass of the above-mentioned polymer (not containing the water-repellent compound) in one embodiment of the present invention, from the viewpoint of improving the hydrophobicity of the resist film. The water-repellent compound may be used alone or in combination of two or more kinds.

[0095] <4-5> Other ingredients In addition to the above-mentioned components, the resist composition of one embodiment of the present invention may contain, as necessary, as optional components, any of the following compounds that are typically used in resist compositions: an organic solvent, a surfactant, an organic carboxylic acid, a dissolution inhibitor, a stabilizer, a dye, and a sensitizing compound.

[0096] Examples of the organic solvent include ethylene glycol monoethyl ether acetate, cyclohexanone, 2-heptanone, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl β-methoxyisobutyrate, ethyl butyrate, propyl butyrate, methyl isobutyl ketone, ethyl acetate, isoamyl acetate, ethyl lactate, toluene, xylene, cyclohexyl acetate, diacetone alcohol, N-methylpyrrolidone, N,N-dimethylformamide, γ-butyrolactone, N,N-dimethylacetamide, propylene carbonate, ethylene carbonate, etc. These organic solvents are used alone or in combination.

[0097] The surfactant is preferably used to improve the coating property. Examples of the surfactant include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene polyoxypropylene block copolymers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters, fluorine-based surfactants, and organosiloxane polymers.

[0098] The content of the surfactant is preferably 0.0001 to 2 parts by mass, and more preferably 0.0005 to 1 part by mass, relative to 100 parts by mass of the acid-reactive compound.

[0099] Examples of the organic carboxylic acid include aliphatic carboxylic acids, alicyclic carboxylic acids, unsaturated aliphatic carboxylic acids, oxycarboxylic acids, alkoxycarboxylic acids, ketocarboxylic acids, benzoic acid derivatives, phthalic acid, terephthalic acid, isophthalic acid, 2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid, etc. When electron beam exposure is performed under vacuum, there is a risk of the organic carboxylic acid volatilizing from the surface of the resist film and contaminating the inside of the drawing chamber, and therefore preferred organic carboxylic acids are aromatic organic carboxylic acids, and among these, for example, benzoic acid, 1-hydroxy-2-naphthoic acid, and 2-hydroxy-3-naphthoic acid are suitable.

[0100] The content of the organic carboxylic acid is preferably from 0.01 to 10 parts by mass, more preferably from 0.01 to 5 parts by mass, and even more preferably from 0.01 to 3 parts by mass, based on 100 parts by mass of the acid-reactive compound.

[0101] The resist composition components are preferably dissolved in the above organic solvent at a solids concentration of 1 to 40 mass %, more preferably 1 to 30 mass %, and even more preferably 3 to 20 mass %.

[0102] When the resist composition according to one embodiment of the present invention contains a polymer, the polymer preferably has a weight average molecular weight of 2000 to 200000, more preferably 2000 to 50000, and even more preferably 2000 to 15000. From the viewpoint of sensitivity, the polydispersity (molecular weight distribution) (Mw / Mn) of the above polymer is preferably 1.0 to 2.0, and more preferably 1.0 to 1.7. In some embodiments of the present invention, the weight average molecular weight and dispersity of the polymer are defined as polystyrene equivalent values ​​measured by GPC.

[0103] The composition of one embodiment of the present invention can be obtained by mixing the components of the above-mentioned composition, and the mixing method is not particularly limited.

[0104] <5> Device manufacturing methods One aspect of the present invention is a method for manufacturing a device, comprising: a resist film formation step of applying the resist composition onto a substrate to form a resist film; a photolithography step of exposing the resist film to active energy rays; and a pattern formation step of developing the exposed resist film to obtain a photoresist pattern.

[0105] The active energy ray may be any active energy ray capable of activating the sulfonium salt to generate an acid, and may be any of visible light, UV, i-line, KrF excimer laser, ArF excimer laser, F 2 Examples include excimer lasers, EUV (extreme ultraviolet), X-rays, electron beams, and ion beams. For the formation of fine patterns, the active energy rays may be KrF excimer laser, ArF excimer laser, F 2 Excimer laser, EUV, X-rays, electron beams, ion beams, etc. are more preferred, and EUV and electron beams are even more preferred.

[0106] A typical device manufacturing method may be followed, except for using a resist composition containing the above-mentioned acid generator. EXAMPLES

[0107] Some aspects of the present invention will be described below based on examples, but the present invention is not limited to these examples in any way.

[0108] <Synthesis of sulfonium salts> <Synthesis of sulfonium salt A-1>

[0109] [ka]

[0110] 7.4 g of 3-iodobenzo[b]thiophene, 15 g of diphenyliodonium perfluorobutanesulfonate, and copper acetate monohydrate (Cu(OAc) 2 H 20.15 g of sulfonium salt A-1 was added to 32.9 g of chlorobenzene (PhCl) and stirred at 75-80°C for 3 hours. The stirred solution was cooled to 20-30°C, and 164.5 g of diisopropyl ether was added to obtain a crude product. The crude product was dissolved in 131.6 g of dichloromethane and washed with 32.9 g of pure water. The solvent was removed from the solution obtained using a rotary evaporator, and 164.5 g of diisopropyl ether was added to obtain 13.3 g of the target product (sulfonium salt A-1).

[0111] <Synthesis of sulfonium salt A-2>

[0112] [ka]

[0113] 6.0 g of 3-iodobenzo[b]thiophene, 15 g of bis(3-trifluoromethylphenyl)iodonium perfluorobutanesulfonate, and 0.15 g of copper acetate monohydrate are added to 32.9 g of ethylbenzene and stirred at 75 to 80°C for 3 hours. 32.9 g of dichloromethane is added to the stirred solution, and the solution is washed with 32.9 g of pure water. The solvent is removed from the resulting solution using a rotary evaporator, and the solution is concentrated to dryness to obtain a crude product. The crude product is purified by silica gel chromatography to obtain 6.0 g of the target product (sulfonium salt A-2).

[0114] <Synthesis of sulfonium salt A-3>

[0115] [ka]

[0116] The same procedure as for the sulfonium salt A-2 is carried out except that diphenyliodonium perfluorobutanesulfonate is used instead of bis(3-trifluoromethylphenyl)iodonium perfluorobutanesulfonate and 2,3-diiodobenzo[b]thiophene is used instead of 3-iodobenzo[b]thiophene, to obtain 11.8 g of the target product (sulfonium salt A-3).

[0117] <Synthesis of sulfonium salt A-4>

[0118] [ka]

[0119] The same procedure as for the sulfonium salt A-2 is carried out except that bis(2,4,6-trimethoxyphenyl)iodonium=perfluorobutanesulfonate is used instead of bis(3-trifluoromethylphenyl)iodonium=perfluorobutanesulfonate, to obtain 7.2 g of the target product (sulfonium salt A-4).

[0120] <Synthesis of sulfonium salt A-5>

[0121] [ka]

[0122] The same procedure as for the sulfonium salt A-2 is carried out except that diphenyliodonium perfluorobutanesulfonate is used instead of bis(3-trifluoromethylphenyl)iodonium perfluorobutanesulfonate and 3-iodonaphtho[2,3-b]thiophene is used instead of 3-iodobenzo[b]thiophene, to obtain 12.4 g of the target product (sulfonium salt A-5).

[0123] <Synthesis of sulfonium salt A-6>

[0124] [ka]

[0125] The same procedure as for the sulfonium salt A-2 is carried out except that bis-(4-fluorophenyl)iodonium=perfluorobutanesulfonate is used instead of phenyliodonium=perfluorobutanesulfonate, to obtain 8.0 g of the target product (sulfonium salt A-6).

[0126] <Synthesis of sulfonium salt A-7>

[0127] [ka]

[0128] <1st process> By carrying out the same procedure as above for sulfonium salt A-2, except that diphenyliodonium methyl sulfate is used instead of diphenyliodonium perfluorobutanesulfonate, 12.0 g of 1-phenyl-3-iodobenzo[b]thiophenium methyl sulfate (sulfonium salt A-7') is obtained.

[0129] <Second process> 5.4 g of sodium 1,1,2-trifluoro-4-hydroxybutanesulfonate and 10 g of sulfonium salt A-7' are added to a mixed solution of 133 g of dichloromethane and 33 g of water, and stirred for 3 hours. The solution after stirring is separated, and the resulting dichloromethane solution is concentrated to dryness using a rotary evaporator to obtain 11.1 g of 1-phenyl-3-iodobenzo[b]thiophenium 1,1,2-trifluoro-4-hydroxybutanesulfonate (sulfonium salt A-7'').

[0130] <3rd process> 11.1 g of the above 1-phenyl-3-iodobenzo[b]thiophenium = 1,1,2-trifluoro-4-hydroxybutanesulfonate (sulfonium salt A-7''), 4.0 g of adamantane carboxylic acid, and 0.3 g of dimethylaminopyridine (DMAP) are added to 115 g of dichloromethane and stirred. Then, 4.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC hydrochloride) is added at 15 ° C or less and the temperature is raised to 25 ° C. After stirring for 20 hours, the reaction liquid is cooled and 10 mass % hydrochloric acid is added to stop the reaction. The organic layer is washed with pure water, and the solvent is distilled off with a rotary evaporator to obtain a crude product. The crude product is purified by silica gel chromatography to obtain 8.6 g of the target product (sulfonium salt A-7).

[0131] <Synthesis of sulfonium salt A-8>

[0132] [ka]

[0133] 30.8 g of sodium 2,2-difluoroacetate-9-(2,7-diiodofluorene)methyl-2-sulfonate and 20 g of 1-phenyl-3-iodobenzo[b]thiophenium methyl sulfate (sulfonium salt A-7') are added to a mixed solvent of 210 g of dichloromethane and 126 g of pure water, and stirred for 3 hours. The solution after stirring is separated, and the organic layer is washed with pure water. The obtained organic layer is concentrated to dryness using a rotary evaporator to obtain 34.1 g of the target product (sulfonium salt A-8).

[0134] <Synthesis of sulfonium salt A-9>

[0135] [ka]

[0136] The same procedure as for the sulfonium salt A-7 is carried out except that sodium 1,1,2-trifluoro-4-hydroxybutanesulfonate is replaced by sodium 1,1-difluoro-2-hydroxyethanesulfonate and adamantanecarboxylic acid is replaced by benzoic acid, to obtain 6.5 g of the target product (sulfonium salt A-9).

[0137] <Synthesis of sulfonium salt A-10>

[0138] [ka]

[0139] The same procedure as for the sulfonium salt A-7 is carried out except that sodium 1,1,2-trifluoro-4-hydroxybutanesulfonate is replaced by sodium 1,1-difluoro-2-trifluoromethyl-2-hydroxyethanesulfonate and adamantanecarboxylic acid is replaced by benzoic acid, to obtain 5.3 g of the target product (sulfonium salt A-10).

[0140] <Synthesis of sulfonium salt A-11>

[0141] [ka]

[0142] By carrying out the same procedure as for the sulfonium salt A-7, except that bis(3-furyl)iodonium methylsulfate is used instead of diphenyliodonium methylsulfate and benzoic acid is used instead of adamantanecarboxylic acid, 8.7 g of the target product (sulfonium salt A-11) is obtained.

[0143] <Synthesis of sulfonium salt A-12>

[0144] [ka]

[0145] The same procedure as for the sulfonium salt A-7 is carried out except that bis(4-iodophenyl)iodonium methyl sulfate is used instead of diphenyliodonium methyl sulfate, sodium 1-trifluoromethyl-3-hydroxypropanesulfonate is used instead of sodium 1,1,2-trifluoro-4-hydroxybutanesulfonate, and benzoic acid is used instead of adamantanecarboxylic acid, to obtain 6.2 g of the target product (sulfonium salt A-12).

[0146] <Comparative sulfonium salt B-1>

[0147] [ka]

[0148] The same procedure as in the synthesis of sulfonium A-2 was carried out except that benzo[b]thiophene was used instead of 3-iodobenzo[b]thiophene, to obtain 10.7 g of the target product (comparative sulfonium salt B-1).

[0149] <Comparative sulfonium salt B-2>

[0150] [ka]

[0151] 17.1 g of potassium perfluorobutanesulfonate and 23.0 g of 4-iodophenyldiphenylsulfonium methylsulfate are added to a mixed solution of 158 g of dichloromethane and 95 g of water, and stirred for 3 hours. The solution after stirring is separated, and the resulting dichloromethane solution is concentrated to dryness using a rotary evaporator to obtain 25.6 g of the target product (comparative sulfonium salt B-2).

[0152] <Comparative sulfonium salt B-3>

[0153] [ka]

[0154] The same procedure as in the synthesis of sulfonium A-7 was carried out except that benzo[b]thiophene was used instead of 3-iodobenzo[b]thiophene, to obtain 9.1 g of the target product (comparative sulfonium salt B-3).

[0155] <Synthesis of sulfonium salt C-1>

[0156] [ka]

[0157] 5.9g of sodium salicylate and 15.0g of 1-phenyl-3-iodobenzo[b]thiophenium methyl sulfate (sulfonium salt A-7') were added to 127g of dichloromethane and 32g of pure water, and the mixture was stirred for 3 hours. The organic layer was washed with pure water, and the solvent was removed using a rotary evaporator to obtain a crude product. The crude product was purified by silica gel chromatography to obtain 10.3g of the target product (sulfonium salt C-1).

[0158] <Synthesis of sulfonium salt C-2>

[0159] [ka]

[0160] The same procedure as in the synthesis of sulfonium C-1 was carried out except that 1-(3-trifluoromethyl)phenyl-3-iodobenzo[b]thiophenium=methylsulfate was used instead of 1-phenyl-3-iodobenzo[b]thiophenium=methylsulfate, to obtain 12.8 g of the target product (sulfonium salt C-2).

[0161] <Synthesis of sulfonium salt C-3>

[0162] [ka]

[0163] The same procedure as in the synthesis of sulfonium C-1 was carried out except that 1-(3-furyl)-3-iodobenzo[b]thiophenium=methylsulfate was used instead of 1-phenyl-3-iodobenzo[b]thiophenium=methylsulfate, to obtain 8.3 g of the target product (sulfonium salt C-3).

[0164] <Synthesis of sulfonium salt C-4>

[0165] [ka]

[0166] The same procedure as in the synthesis of sulfonium salt C-1 was carried out except that sodium 2,7-diiodofluorene-9-carboxylate was used instead of sodium salicylate, to obtain 18.5 g of the target product (sulfonium salt C-4).

[0167] <Synthesis of sulfonium salt C-5>

[0168] [ka]

[0169] The above ammonium salt (C-5-a) is synthesized with reference to WO2023 / 053877. 77 g of dichloromethane, 19.3 g of pure water, and 8.5 g of 1-phenyl-2,3-diiodobenzo[b]thiophenium methyl sulfate are added to 6.6 g of the above ammonium salt (C-5-a) and stirred for 3 hours. The organic layer is separated and washed with a 3% by mass aqueous sodium carbonate solution. After washing with pure water until neutral, the organic layer is distilled with a rotary evaporator to obtain a crude product. The crude product is purified by silica gel chromatography to obtain 6.8 g of the target product (sulfonium salt C-5).

[0170] <Synthesis of Comparative Sulfonium Salt D-1>

[0171] [ka]

[0172] The same procedure as in the synthesis of sulfonium C-1 was carried out except that 1-phenylbenzo[b]thiophenium=methylsulfate was used instead of 1-phenyl-3-iodobenzo[b]thiophenium=methylsulfate, to obtain 13.1 g of the target product (comparison sulfonium salt D-1).

[0173] <Synthesis of Comparative Sulfonium Salt D-2>

[0174] [ka]

[0175] The same procedure as in the synthesis of sulfonium C-4 above is carried out except that sodium fluorene-9-carboxylate is used instead of sodium 2,7-diiodofluorene-9-carboxylate, and 1-phenylbenzo[b]thiophenium=methylsulfate is used instead of 1-phenyl-3-iodobenzo[b]thiophenium=methylsulfate, to obtain 15.9 g of the target product (comparative sulfonium salt D-2).

[0176] <Amine D-3> Amine D-3 manufactured by Tokyo Chemical Industry Co., Ltd. is used, but the present invention is not limited thereto. [ka]

[0177] <Synthesis of Polymer A> 8.0 g of polyhydroxystyrene (weight average molecular weight 8000) and 0.010 g of 35% by mass aqueous hydrochloric acid solution are dissolved in 28 g of dehydrated dioxane. A solution of 2.73 g of cyclohexyl vinyl ether dissolved in 2.80 g of dehydrated dioxane is dropped into the polyhydroxystyrene solution over 30 minutes. After dropping, the mixture is stirred at 40°C for 2 hours. After stirring and cooling, 0.014 g of dimethylaminopyridine is added to obtain a polymer solution. The polymer solution is then dropped into 260 g of pure water to precipitate the polymer. The solid obtained by separating the polymer through reduced pressure filtration is washed twice with 300 g of pure water, and then vacuum dried to obtain 9.2 g of polymer A shown below as a white solid. The monomer ratio of the polymer unit in the present invention is not limited to the following.

[0178] [ka]

[0179] [Examples 1 to 24 and Comparative Examples 1 to 3] <Electron beam sensitivity evaluation> A sample of the resist composition used in Example 1 is prepared by adding 400 mg of the polymer A resin, 80 mg of the sulfonium salt A-1 synthesized above as a photoacid generator (PAG), and 16 mg of the comparative sulfonium salt D-1 synthesized above as an acid diffusion controller to 5000 mg of cyclohexanone. The resist composition used in Examples 2 to 24 and Comparative Examples 1 to 3 is prepared by adding the same amount of polymer A as in Example 1, the same molar amount of photoacid generator as in Example 1, and the same molar amount of acid diffusion controller as in Example 1 to the same amount of cyclohexanone as in Example 1. The photoacid generators (PAG) used in Examples 2 to 24 and Comparative Examples 1 to 3 are the sulfonium salts A-1 to A-12 and comparative sulfonium salts B-1 to B-3 obtained above, and the acid diffusion controllers are the sulfonium salts C-1 to C-5, comparative sulfonium salts D-1 and D-2, and amine D-3 synthesized above.

[0180] The electron beam sensitivity evaluation is carried out as follows. The above resist composition sample is spin-coated on a silicon wafer previously modified with hexamethylenedisilazane. By pre-baking this on a hot plate at 110 °C for 1 minute, a substrate with a coating film having a thickness of 200 nm is obtained. With respect to the coating film of the substrate, using an electron beam lithography apparatus, exposure is performed while changing the exposure dose so that a 100 nm 1:1 line and space pattern is formed by an electron beam of 30 keV. The substrate after electron beam irradiation is heated on a hot plate at 110 °C for 1 minute. Development is carried out for 1 minute using a developer (2.38 mass% aqueous solution of tetramethylammonium hydroxide), and then rinsing with pure water gives a 100 nm line and space pattern. The sensitivity by electron beam irradiation is determined with the electron beam irradiation dose at this time being Esize [μC / cm 2 . Also, the obtained pattern is observed and LWR [nm] is measured. For the above other samples, sensitivity evaluation and LWR measurement are carried out in the same manner as above. The sample compositions and results are shown in Table 1.

[0181] In Table 1, the sensitivity and LWR of each sample are calculated as relative values based on the evaluation results of the samples (Examples 1 to 24 and Comparative Examples 2 to 3) with respect to Comparative Example 1 (photoacid generator: sulfonium salt B-1, acid diffusion controller: comparative sulfonium salt D-1) with the sensitivity being 100 and the LWR being 1. A smaller numerical value for sensitivity and LWR indicates a more excellent effect.

[0182] [Examples 25 to 27 and Comparative Example 4] [EUV Sensitivity Evaluation] Samples of the resist compositions used in Examples 25 to 27 and Comparative Example 4 are prepared by the same method as the electron beam sensitivity evaluation.

[0183] EUV sensitivity evaluation is performed as follows. The resist composition sample is spin-coated onto a silicon wafer that has been previously modified with hexamethylenedisilazane. This is pre-baked on a hot plate at 110°C for 1 minute to obtain a substrate on which a coating film with a thickness of 200 nm has been formed. The coating film on the substrate is irradiated with an EUV exposure device while changing the exposure dose. After EUV exposure, the substrate is heated on a hot plate at 110°C for 1 minute. It is then developed for 1 minute using a 2.38% by mass aqueous solution of tetramethylammonium hydroxide, and then rinsed with pure water to obtain a substrate with a size of 1 x 1 cm. 2 The obtained pattern is subjected to thickness measurement using a contact type thickness meter, and a sensitivity curve is created to obtain the sensitivity Esize [mJ / cm 2 ] is calculated. Esize at this time is the exposure dose when the film thickness becomes 50% of the maximum film thickness. The sample composition and results are shown in Table 2.

[0184] In Table 2, the sensitivity of each sample is calculated as a relative value to the sensitivity of Comparative Example 4 (photoacid generator: comparative sulfonium salt B-3, acid diffusion controller: comparative sulfonium salt D-1) which is set at 100, and the evaluation results of the samples (Examples 25 to 27) in comparison thereto. A smaller sensitivity value indicates a more excellent effect.

[0185] The sulfonium salts used as the photoacid generators (PAGs) (the sulfonium salts A-1 to A-12 and the comparative sulfonium salts B-1 to B-3) are shown below.

[0186] [ka]

[0187] [ka]

[0188] As the acid diffusion controller, sulfonium salts C-1 to C-5, comparative sulfonium salts D-1 and D-2, and amine D-3 are shown below.

[0189] [ka]

[0190] [ka]

[0191] [Table 1]

[0192] [Table 2]

[0193] It can be seen that Examples 1 to 24 in Table 1 tend to have superior sensitivity and LWR compared to Comparative Examples 1 to 3. From these results, it is presumed that the sulfonium salt in one embodiment of the present invention has a structure having iodine in the benzo[b]thiophene skeleton, and thus has high sensitivity to electron beams, efficiently absorbs active energy rays, efficiently generates acid, and has an excellent effect on LWR.

[0194] It can be seen that in Examples 15 to 19, the combination of sulfonium salt A-1 and any of sulfonium salts C-1 to C-5 improves both the sensitivity and LWR compared to Example 1, which used comparative sulfonium salt D-1 that does not contain iodine as an acid diffusion controller. This result shows that the sulfonium salt of one embodiment of the present invention can also function as an acid diffusion controller by changing the anion, and that the sensitivity is further increased by including iodine in the structure.

[0195] It can be seen that Examples 25 to 27 in Table 2 tend to have superior sensitivity compared to Comparative Example 4. From these results, it is presumed that the sulfonium salt in one embodiment of the present invention has a structure having iodine in the benzo[b]thiophene skeleton, and thus has high sensitivity to EUV and efficiently generates acid.

[0196] In the above Examples 1 to 27, polymer A was used as the copolymer, but the sulfonium salt of one embodiment of the present invention also tends to have excellent sensitivity and lithography properties such as LWR when combined with a copolymer other than the above polymer A.

[0197] In addition, even if it is a compound other than the examples, as long as it is a sulfonium salt having the structure of the above formula (1), it has an excellent effect on sensitivity and LWR as compared to the comparative example compounds, similar to the example compounds. Examples of the compounds other than the examples include the anion (Z ‐ ) is a borane anion, or a compound having the cation structure in the above formula (1). Specific examples include the above-mentioned compound groups. [Industrial Applicability]

[0198] The sulfonium salt according to one embodiment of the present invention has a benzo[b]thiophene skeleton with low fat solubility and iodine in the cationic portion of the sulfonium salt, and therefore has excellent absorption against electron beam (EB) or extreme ultraviolet (EUV) when used in a resist composition, and can provide high sensitivity. In addition, when the sulfonium salt is used in a resist composition as a photodecomposable base, which is one of the acid diffusion control agents, the undecomposed sulfonium salt acts as an acid diffusion control agent in the unexposed and exposed areas, and is ionized in the exposed area to generate secondary electrons, which can improve the generation of acid from the photoacid generator, thereby reducing LWR (Line width roughness) in fine patterns in lithography.

Claims

1. A sulfonium salt represented by the following formula (1): 【Chemistry 1】 (In the above formula (1), R １ is any one selected from the group consisting of a hydrogen atom; a hydroxyl group; a carboxyl group; an electron-withdrawing group; an amino group which may have a substituent; a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenyl group having 2 to 30 carbon atoms which may have a substituent; an aryl group having 5 to 30 carbon atoms which may have a substituent; and a heteroaryl group having 3 to 30 carbon atoms which may have a substituent; Ar is an optionally substituted aryl group having 6 to 14 carbon atoms or an optionally substituted heteroaryl group having 3 to 20 carbon atoms, R １ If there are two or more, two R １ may form a ring directly via a single bond or via any divalent group selected from the group consisting of oxygen atom-, sulfur atom-, and nitrogen atom-containing groups, n is an integer from 1 to 3; When n is 1, m is an integer from 0 to 6; When n is 2, m is an integer from 0 to 8; when n is 3, m is an integer from 0 to 10; The sulfonium salt in the above formula (1) has at least one iodine atom in the sulfonium cation structure, X － is a monovalent anion.)

2. 2. The sulfonium salt according to claim 1, wherein Ar is an aryl group having 1 to 5 ring members or a heteroaryl group having 1 to 5 ring members.

3. 2. The sulfonium salt according to claim 1, wherein the heteroatom of the heteroaryl group in Ar is any one selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

4. When Ar has two or more substituents, the two substituents may be the same or different. The sulfonium salt according to claim 1, wherein the two substituents may be bonded to each other directly via a single bond or via at least one selected from the group consisting of a divalent heteroatom-containing group and an alkylene group to form a ring structure.

5. The sulfonium salt according to claim 1, wherein Ar in the above formula (1) is selected from the group consisting of a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, a benzofuryl group, an indole group, a thienyl group, a furyl group, a dibenzofuryl group, a carbazole group, a benzothienyl group, a dibenzothienyl group, an imidazole group, a pyridinyl group, a chromenyl group and a pyrrole group, each of which may have a substituent.

6. 2. The sulfonium salt according to claim 1, wherein the anion is at least one selected from the group consisting of a halogen anion, a hydroxide anion, a borane anion, a sulfate anion, a carbonate anion, a sulfonate anion, a carboxylate anion, an imide anion, and a methide anion.

7. The sulfonium salt according to claim 1, wherein the anion is represented by the following formula (2): 【Chemistry 2】 (In the above formula (2), A － is a sulfonate or carboxylate anion, Q is any one selected from the group consisting of a hydrogen atom; a fluorine atom; and a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may have a substituent; r is an integer from 0 to 3; Multiple Q may be the same or different, T is any one selected from the group consisting of a single bond; a linear, branched or cyclic alkylene group having 1 to 30 carbon atoms which may have a substituent; a linear, branched or cyclic alkenylene group having 2 to 30 carbon atoms which may have a substituent; an arylene group having 5 to 30 carbon atoms which may have a substituent; and a heteroarylene group having 3 to 30 carbon atoms which may have a substituent; At least one methylene group in T may be substituted with a divalent heteroatom-containing group; L is a single bond or a divalent heteroatom-containing group; Z is an organic group having 1 to 30 carbon atoms which may have a substituent.

8. An acid generator comprising the sulfonium salt according to any one of claims 1 to 7.

9. A resist composition comprising the acid generator according to claim 8 and an acid-reactive compound.

10. The resist composition according to claim 9, further comprising an acid diffusion controller.

11. The resist composition according to claim 9, further comprising a water-repellent polymer.

12. forming a resist film on a substrate using the resist composition according to claim 9; exposing the resist film to active energy rays; and developing the exposed resist film.

13. The method for producing a device according to claim 12 , wherein the active energy rays are extreme ultraviolet rays or electron beams.

14. The method for producing a device according to claim 13 , wherein the resist composition further contains an acid diffusion controller.

15. The method for manufacturing a device according to claim 13 , wherein the resist composition further contains a water-repellent polymer.

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