Onium salt, acid diffusion controller, resist composition, and pattern forming method

Abstract

To provide an onium salt for use in a resist composition, featuring high sensitivity and superior resolution, improved roughness and dimensional uniformity, and reduced resist pattern collapse.SOLUTION: The present invention provides an onium salt represented by the following formula (1) (where RALU denotes a tertiary ether, a tertiary carbonate, or an acetal formed with an adjacent oxygen atom. I denotes an iodine atom. Ra denotes a C1-20 hydrocarbyl group optionally including a heteroatom. Z+ denotes an onium cation).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an onium salt, an acid diffusion controller, a resist composition, and a pattern forming method. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming increasingly miniaturized. This is due to the increasing popularity of 5G high-speed communications and artificial intelligence (AI), which require high-performance devices to process these. The most advanced miniaturization technology is extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, which is currently used to mass-produce 5 nm node devices. Furthermore, the use of EUV lithography is being considered for next-generation 3 nm node devices and the next-generation 2 nm node devices.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem. To ensure resolution in fine patterns with dimensions of 45 nm and smaller, it has been suggested that controlling acid diffusion is important, in addition to improving dissolution contrast, as has been proposed previously (Non-Patent Document 1). However, because chemically amplified resist compositions increase sensitivity and contrast through acid diffusion, attempts to minimize acid diffusion by lowering the post-exposure bake (PEB) temperature or shortening the time result in significant decreases in sensitivity and contrast.

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

[0005] It is effective to suppress acid diffusion by adding an acid generator that generates bulky acid. Therefore, it has been proposed to incorporate repeating units derived from onium salts having polymerizable unsaturated bonds into a polymer. In this case, the polymer also functions as an acid generator (polymer-bound acid generator). Patent Document 1 proposes sulfonium salts and iodonium salts having polymerizable unsaturated bonds that generate specific sulfonic acids. Patent Document 2 proposes sulfonium salts in which sulfonic acids are directly linked to the main chain.

[0006] The acid-labile groups used in (meth)acrylate polymers for ArF resist compositions undergo deprotection using a photoacid generator that generates sulfonic acid substituted with a fluorine atom at the α-position, but not with an acid generator that generates sulfonic acid or carboxylic acid not substituted with a fluorine atom at the α-position. When a sulfonium salt or iodonium salt that generates sulfonic acid substituted with a fluorine atom at the α-position is mixed with a sulfonium salt or iodonium salt that generates sulfonic acid not substituted with a fluorine atom at the α-position, the sulfonium salt or iodonium salt that generates sulfonic acid not substituted with a fluorine atom at the α-position undergoes ion exchange with the sulfonic acid not substituted with a fluorine atom at the α-position. The sulfonic acid substituted with a fluorine atom at the α-position generated by light reverts to the sulfonium salt or iodonium salt through ion exchange, and the sulfonium salt or iodonium salt of the sulfonic acid or carboxylic acid not substituted with a fluorine atom at the α-position functions as a quencher. A resist composition has been proposed that uses a sulfonium salt or iodonium salt that generates a carboxylic acid as a quencher (Patent Document 3).

[0007] Sulfonium salt quenchers that generate various carboxylic acids have been proposed. In particular, sulfonium salts of salicylic acid, β-hydroxycarboxylic acid (Patent Document 4), salicylic acid derivatives (Patent Documents 5 and 6), fluorosalicylic acid (Patent Document 7), and hydroxynaphthoic acid (Patent Document 8) have been proposed. In particular, salicylic acid has the effect of suppressing acid diffusion through intramolecular hydrogen bonding between the carboxylic acid and the hydroxy group.

[0008] Furthermore, because iodine atoms have a very high absorption rate for EUV light with a wavelength of 13.5 nm, it has been confirmed that secondary electrons are generated from iodine during exposure, which has attracted attention in EUV lithography. Patent Documents 9 and 10 propose sulfonium salt-type quenchers in which iodine atoms are introduced into benzoic acid or salicylic acid. While this has been confirmed to improve lithography performance to a certain extent, iodine atoms are not highly soluble in organic solvents, and there are concerns about precipitation in resist solvents.

[0009] In response to the demand for further miniaturization, a problem has arisen in that swelling occurs due to the developer during alkaline development, particularly in positive resists, resulting in pattern collapse during fine pattern formation. In order to meet such challenges in miniaturization, the development of new resist compositions is important, and there is a need for the development of onium salt-type quenchers that have good sensitivity, adequately controlled acid diffusion, excellent solvent solubility, and are effective in suppressing pattern collapse. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-045311 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-178317 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-114431 [Patent Document 4] WO2018 / 159560 [Patent Document 5] Japanese Patent Publication No. 2020-203984 [Patent Document 6] Japanese Patent Publication No. 2020-91404 [Patent Document 7] Japanese Patent Publication No. 2020-91312 [Patent Document 8] Japanese Patent Application Publication No. 2019-120760 [Patent Document 9] Japanese Patent Publication No. 2022-67056 [Patent Document 10] Patent No. 6702264 [Non-patent literature]

[0011] [Non-Patent Document 1] SPIE Vol. 6520 65203L-1 (2007) Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in view of the above circumstances, and has an object to provide a novel onium salt for use in a resist composition that can achieve high sensitivity and excellent resolution, improve LWR (roughness) and CDU (dimensional uniformity), and suppress resist pattern collapse in lithography using far ultraviolet, EUV, or the like, whether the resist is positive or negative; an acid diffusion controller comprising this onium salt; a resist composition that contains this acid diffusion inhibitor; and a pattern formation method that uses this resist composition. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides: The present invention provides an onium salt represented by the following general formula (1): [ka] (In the formula, R ALU represents a tertiary ether, a tertiary carbonate, or an acetal, which may have a heteroatom, formed together with the adjacent oxygen atom. I represents an iodine atom. R a is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. n1 is an integer of 0 or 1. n2 and n3 are integers of 1 or 2. When n2 and n3 are 1, I and -OR ALU are bonded to adjacent carbon atoms. Also, when either or both of n2 and n3 are 2, I and -OR ALUare bonded to adjacent carbon atoms. n4 is an integer from 0 to 3. When n4 ≥ 2, multiple R a may be bonded to each other to form a ring structure together with the carbon atoms to which they are attached. + represents an onium cation.

[0014] The onium salt of the present invention is useful as a novel onium salt for use in a resist composition that can achieve high sensitivity and excellent resolution, improve LWR and CDU, and suppress collapse of the resist pattern, whether in positive or negative lithography. Furthermore, the onium salt of the present invention can exhibit excellent solvent solubility.

[0015] Furthermore, R in the general formula (1) ALU The structure is preferably represented by the following general formula (ALU-1) or (ALU-2). [ka] (In formula (ALU-1), R 21’ , R 22’ , and R 23’ are each independently a hydrocarbyl group having 1 to 12 carbon atoms which may have a heteroatom, and R 21’ , R 22’ , and R 23’ Any two of these may be bonded to each other to form a ring. t is an integer of 0 or 1. In formula (ALU-2), R 24’ , and R 25’ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 26’ is a hydrocarbyl group having 1 to 20 carbon atoms, or R 24’ or R 25’ and bond to each other, and the carbon atoms to which they are bonded and X a may form a heterocyclic group having 3 to 20 carbon atoms together with X. Furthermore, -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. * represents a bond with the adjacent oxygen atom.)

[0016] Such an onium salt will function better as an acid diffusion controller contained in the resist composition.

[0017] Furthermore, Z in the general formula (1) + is preferably an onium cation represented by any one of the following general formulae (Cation-1) to (Cation-3). [ka] (In formulas (Cation-1) to (Cation-3), R 11’ ~R 19’ are each independently a linear, branched or cyclic hydrocarbyl group having 1 to 30 carbon atoms, which may contain a heteroatom and may be saturated or unsaturated.

[0018] Such an onium salt will function particularly well as an acid diffusion controller contained in a resist composition.

[0019] The present invention also provides an acid diffusion controller comprising the onium salt of the present invention.

[0020] The onium salt of the present invention is useful as an acid diffusion controller.

[0021] The present invention also provides a resist composition containing the acid diffusion controller of the present invention.

[0022] By including the acid diffusion controller, the resist composition becomes excellent.

[0023] Furthermore, it is preferable that the composition contains an acid generator that generates an acid.

[0024] In such a case, the onium salt functions as an acid diffusion controller, and the resist composition of the present invention functions.

[0025] The acid generator is preferably one that generates a sulfonic acid, an imide acid, or a methide acid.

[0026] Such a compound is more suitable as an acid generator.

[0027] It is also preferable that the solvent contains an organic solvent.

[0028] In such a case, each component can be dissolved, and the coating properties of the composition are improved.

[0029] It is preferable that the adhesive further contains a base polymer.

[0030] Such a composition is suitable as a resist composition.

[0031] The base polymer preferably contains a repeating unit represented by the following general formula (a1) and / or a repeating unit represented by the following general formula (a2). [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 Y is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. 2 is a single bond or an ester bond. 3 is a single bond, an ether bond, or an ester bond. 11 and R 12 are each independently an acid labile group. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 14 represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of whose carbon atoms may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4, provided that 1≦a+b≦5.

[0032] Such a compound contains an acid labile group and is suitable as a positive resist composition.

[0033] The resist composition is preferably a chemically amplified positive resist composition.

[0034] The resist composition of the present invention can function as a chemically amplified positive resist composition.

[0035] Alternatively, the resist composition is preferably a chemically amplified negative resist composition.

[0036] The resist composition of the present invention can also function as a chemically amplified negative resist composition.

[0037] It is also preferred that the base polymer does not contain any acid labile groups.

[0038] Such a composition does not contain acid labile groups and is suitable as a negative resist composition.

[0039] It is preferable that the base polymer further contains at least one repeating unit selected from the repeating units represented by the following general formulas (f1) to (f3). [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 11Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 R is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, or may be a combination thereof, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and / or a hydroxy group. 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 and R 26 and R 27 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. - is a non-nucleophilic counterion.

[0040] Such a compound functions as an acid generator in the base polymer.

[0041] It is preferable that the composition further contains a surfactant.

[0042] Such a material makes it possible to improve and control the coatability of the resist composition.

[0043] The present invention also provides a pattern forming method, comprising the steps of: forming a resist film on a substrate using the above-mentioned resist composition; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

[0044] Such a pattern forming method can form a good pattern.

[0045] The high energy beam can be KrF excimer laser light, ArF excimer laser light, electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

[0046] The use of such high energy rays allows for better pattern formation. [Effects of the Invention]

[0047] The novel onium salt of the present invention functions well as an acid diffusion controller (quencher) in a resist composition, providing high sensitivity and excellent dissolution contrast, thereby enabling the construction of a high-resolution pattern profile with small LWR and CDU and excellent rectangularity. Furthermore, the novel onium salt of the present invention suppresses swelling of the resist pattern during alkaline development, enabling the formation of a pattern that is resistant to collapse, making it possible to provide a resist composition that uses the novel onium salt of the present invention and a pattern formation method that uses the resist composition, which are excellent in the formation of fine patterns. DETAILED DESCRIPTION OF THE INVENTION

[0048] There has been a demand for the development of an onium salt type quencher that has good sensitivity, adequately controlled acid diffusion, excellent solvent solubility, and is effective in suppressing pattern collapse.

[0049] As a result of extensive research conducted by the inventors in order to achieve the above-mentioned object, they discovered that a resist composition containing an onium salt having a specific structure as an acid diffusion controller can produce a resist film with excellent sensitivity and resolution, with small LWR in line patterns and small CDU in hole patterns and dot patterns, and furthermore, can suppress swelling during development, making it extremely effective for precise microfabrication, which led to the completion of the present invention.

[0050] That is, the present invention provides an onium salt represented by the following general formula (1): [ka] (In the formula, R ALU represents a tertiary ether, a tertiary carbonate, or an acetal, which may have a heteroatom, formed together with the adjacent oxygen atom. I represents an iodine atom. R a is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. n1 is an integer of 0 or 1. n2 and n3 are integers of 1 or 2. When n2 and n3 are 1, I and -OR ALU are bonded to adjacent carbon atoms. Also, when either or both of n2 and n3 are 2, I and -OR ALU are bonded to adjacent carbon atoms. n4 is an integer from 0 to 3. When n4 ≥ 2, multiple R a may be bonded to each other to form a ring structure together with the carbon atoms to which they are attached. + represents an onium cation.

[0051] The present invention will be described in detail below, but the present invention is not limited thereto.

[0052] [Onium salts] The onium salt of the present invention is represented by the following general formula (1). [ka] (In the formula, R ALUrepresents a tertiary ether, a tertiary carbonate, or an acetal, which may have a heteroatom, formed together with the adjacent oxygen atom. I represents an iodine atom. R a is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. n1 is an integer of 0 or 1. n2 and n3 are integers of 1 or 2. When n2 and n3 are 1, I and -OR ALU are bonded to adjacent carbon atoms. Also, when either or both of n2 and n3 are 2, I and -OR ALU are bonded to adjacent carbon atoms. n4 is an integer from 0 to 3. When n4 ≥ 2, multiple R a may be bonded to each other to form a ring structure together with the carbon atoms to which they are attached. + represents an onium cation.

[0053] In the above general formula (1), R ALU is any one of a tertiary ether, a tertiary carbonate, and an acetal which may have a heteroatom, formed together with the adjacent oxygen atom, and specifically, is preferably represented by the following formula (ALU-1) or (ALU-2). [ka]

[0054] In the above general formula (ALU-1), R 21’ , R 22’ , and R 23’ are each independently a hydrocarbyl group having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and R 21’ , R 22’ , and R 23’ Any two of these may be bonded to each other to form a ring. t is an integer of 0 or 1. In formula (ALU-2), R 24’ , and R 25’ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 26’ is a hydrocarbyl group having 1 to 20 carbon atoms, or R 24’ or R 25’and bond to each other, and the carbon atoms to which they are bonded and X a may form a heterocyclic group having 3 to 20 carbon atoms together with X. Furthermore, -CH2- contained in the above hydrocarbyl group and heterocyclic group may be replaced with -O- or -S-. a represents an oxygen atom or a sulfur atom. * represents a bond with the adjacent oxygen atom.

[0055] R in the above general formula (1) ALU R represented by the above general formula (ALU-1) may or may not have a cyclic structure. ALU has a cyclic structure, and R 21’ , R 22’ , and R 23’ When R 21’ , R 22’ , and R 23’ At least one of R represented by the above general formula (ALU-2) can have a cyclic structure. ALU has a cyclic structure, and R 26’ But R 24’ or R 25’ and carbon atoms and X a When R does not form a heterocyclic group together with 24’ , R 25’ , and R 26’ At least one of them can have a cyclic structure.

[0056] Specific examples of the structure represented by the above general formula (ALU-1) include, but are not limited to, those shown below. [ka]

[0057] [ka]

[0058] [ka]

[0059] Specific examples of the structure represented by the above general formula (ALU-2) include, but are not limited to, those shown below. [ka]

[0060] In the above general formula (1), I and -OR ALU must be bonded to adjacent carbon atoms. Specifically, when n2 and n3 are 1, I and -OR ALU are bonded to adjacent carbon atoms. Also, when either or both of n2 and n3 are 2, I and -OR ALU are bonded to adjacent carbon atoms. Iodine atoms have a large molecular weight, so when they are in an anionic structure, they have the characteristic of having small acid diffusion. Furthermore, the absorption of EUV light with a wavelength of 13.5 nm by iodine is very large, so secondary electrons are generated from iodine during exposure, resulting in high sensitivity. These make it possible to construct a resist with high sensitivity, low LWR, and low CDU. In addition, iodine atoms have an electron-withdrawing effect, so when I and -OR ALU and are adjacent to each other, ALU The acidity of the aromatic alcohol produced by elimination of the acid labile group from the compound is increased, and the solubility in an alkaline developer is improved.

[0061] In the above general formula (1), R ais a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. Some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with halogen atoms, and -CH2- constituting the hydrocarbyl group may be substituted with -O- or -C(=O)-. 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, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl; saturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl; unsaturated cyclic hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl; and groups obtained by combining these groups. In addition, 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 or a halogen atom, and some of the -CH- constituting the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group 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 sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0062] In the above general formula (1), n1 is an integer of 0 or 1. When n1=0, it represents a benzene ring, and when n1=1, it represents a naphthalene ring, but from the viewpoint of solvent solubility, n1=0, i.e., a benzene ring, is preferred.

[0063] In the above general formula (1), n2 and n3 are integers of 1 or 2. From the viewpoint of procuring starting materials, it is preferable that n2 and n3 are each an integer of 1.

[0064] In the general formula (1), n4 is an integer of 0 to 3. When n4 is 2 or more, a plurality of R a may be bonded to each other to form a ring structure together with the carbon atoms to which they are bonded. When a ring structure is formed, specific examples include a 5-membered ring and a 6-membered ring structure.

[0065] Examples of the anion of the onium salt represented by the general formula (1) include, but are not limited to, the following: In addition, the substitution position of the substituent on the aromatic ring is not limited to this as long as the groups bounded by n2 and n3 are adjacent to each other.

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] In the above general formula (1), Z +represents an onium cation. Specific examples include sulfonium cations, iodonium cations, ammonium cations, and phosphonium cations, and are preferably the sulfonium cations, iodonium cations, and ammonium cations shown below.

[0073] In the above general formula (1), Z + is preferably represented by any one of the following general formulas (Cation-1) to (Cation-3). [ka]

[0074] In the above general formulas (Cation-1) to (Cation-3), R 11’ ~R 19’are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 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; 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 groups, with aryl groups being preferred. In addition, some of the hydrogen atoms of the hydrocarbyl group may be substituted with a heteroatom-containing group such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and a heteroatom-containing group such as an oxygen atom, a sulfur atom or a nitrogen atom may be present between the carbon atoms of these groups, and as a result, the group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like.

[0075] Also, R 11’ and R 12’ However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the sulfonium cation represented by formula (Cation-1) include those represented by the following formula: [ka] (In the formula, the dashed line indicates R 13 )

[0076] Examples of the cation of the sulfonium salt represented by formula (Cation-1) include, but are not limited to, those shown below.

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

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[0082]

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[0083]

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[0084]

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[0085]

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[0086]

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[0087]

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[0088]

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[0089]

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[0090]

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[0091]

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[0092]

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[0093]

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[0094]

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[0095]

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[0096]

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[0097]

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[0098] [ka]

[0099] [ka]

[0100] [ka]

[0101] Examples of the iodonium cation represented by the above general formula (Cation-2) include, but are not limited to, those shown below. [ka]

[0102] [ka]

[0103] Examples of the ammonium cation represented by the above general formula (Cation-3) include, but are not limited to, those shown below. [ka]

[0104] Examples of specific structures of the onium salt of the present invention include any combination of the above-mentioned anions and cations.

[0105] The onium salt of the present invention can be synthesized, for example, by ion-exchanging a hydrochloride or carbonate having an onium cation with a corresponding benzoic acid derivative.

[0106] When the onium salt of the present invention is coexisted with a strong acid-generating onium salt, such as a sulfonic acid, imide acid, or methide acid fluorinated at the α-position (hereinafter collectively defined as a strong acid), the corresponding carboxylic acid and strong acid are generated by irradiation with light. Meanwhile, in areas with low exposure, a large amount of undecomposed onium salt remains. While strong acids function as catalysts to induce deprotection reactions of the base resin, the onium salt of the present invention hardly induces deprotection reactions. The strong acid undergoes ion exchange with the remaining carboxylic acid sulfonium salt to form a strong acid onium salt, which releases carboxylic acid in return. In other words, the strong acid is neutralized by the carboxylic acid onium salt through ion exchange. That is, the onium salt of the present invention functions as a quencher (acid diffusion controller). This onium salt-type quencher generally tends to produce a smaller LWR of the resist pattern than quenchers using amine compounds.

[0107] The salt exchange between the strong acid and the carboxylic acid onium salt is repeated countless times. The location where the strong acid is generated at the end of exposure is different from the location where the strong acid-generating onium salt was initially present. It is presumed that the repeated cycle of acid generation by light and salt exchange averages out the acid generation points, which reduces the LWR of the resist pattern after development.

[0108] As described above, the onium salt of the present invention functions as an acid diffusion controller, particularly as an acid diffusion controller (quencher) for a resist composition, and an acid diffusion controller comprising the onium salt of the present invention is preferably contained in a resist composition. More specifically, a resist composition containing the onium salt of the present invention as an acid diffusion controller in lithography, whether positive or negative, provides a resist film with excellent sensitivity and resolution, small LWR in line patterns, and small CDU in hole patterns and dot patterns, and further suppresses swelling during development and resist pattern collapse, making it extremely effective for precise microfabrication.

[0109] Furthermore, the onium salt of the present invention has a tertiary alkyl or acetal acid labile group introduced therein, which improves its fat solubility, and despite containing an iodine atom, it exhibits sufficient solubility in organic solvents, so there is no risk of precipitation of the onium salt in a resist solvent.

[0110] [Acid diffusion controller] The acid diffusion controller of the present invention comprises the onium salt of the present invention. The acid diffusion controller of the present invention can also be called, for example, a benzoic acid-type PDQ (photodegradable quencher) having an iodophenol-protected tertiary ether structure.

[0111] As described above, the onium salt of the present invention can be used as an acid diffusion controller (quencher) for a resist composition. Therefore, the acid diffusion controller comprising the onium salt of the present invention provides a resist film with excellent sensitivity and resolution, small LWR in line patterns, and small CDU in hole patterns and dot patterns. Furthermore, it can suppress swelling during development and resist pattern collapse, making it an extremely effective acid diffusion controller for a resist composition for precise microfabrication.

[0112] In addition, the acid diffusion controller of the present invention can exhibit sufficient solubility in organic solvents, and there is no risk of precipitation in resist solvents.

[0113] [Resist composition] The resist composition of the present invention contains the acid diffusion controller of the present invention.

[0114] The resist composition of the present invention may be a positive-working (chemically amplified positive-working) or a negative-working (chemically amplified negative-working) resist composition.

[0115] The resist composition of the present invention contains an acid diffusion controller comprising the onium salt of the present invention, and therefore the resist film exhibits excellent sensitivity and resolution, has small LWR in line patterns, and small CDU in hole patterns and dot patterns, and further suppresses swelling during development and resist pattern collapse, making it an extremely effective resist composition for precise microfabrication.

[0116] Furthermore, the acid diffusion controller of the present invention exhibits sufficient solubility in organic solvents, so there is no risk of precipitation in resist solvents.

[0117] The content of the onium salt of the present invention in the resist composition is preferably 0.001 to 50 parts by mass, and more preferably 0.01 to 40 parts by mass, per 100 parts by mass of the base polymer described below. The onium salt of the present invention may be used alone, or two or more types may be used in combination.

[0118] The resist composition of the present invention may further contain, in addition to the acid diffusion controller of the present invention, the following components, for example.

[0119] [Base polymer] The resist composition (resist material) of the present invention may further comprise a base polymer. In the case of a positive resist composition, the base polymer comprises a repeating unit containing an acid labile group. As the repeating unit containing an acid labile group, a repeating unit represented by the following general formula (a1) (hereinafter also referred to as repeating unit a1) and / or a repeating unit represented by the following general formula (a2) (hereinafter also referred to as repeating unit a2) is preferred.

[0120] [ka]

[0121] In the above general formulas (a1) and (a2), R A are each independently a hydrogen atom or a methyl group. 1 Y is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. 2 is a single bond or an ester bond. 3 is a single bond, an ether bond, or an ester bond. 11 and R 12are each independently an acid labile group. When the base polymer contains both the repeating unit a1 and the repeating unit a2, R 11 and R 12 R may be the same or different. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of the carbon atoms of which may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4, provided that 1≦a+b≦5.

[0122] Examples of the monomer that provides the repeating unit a1 include, but are not limited to, the following: A and R 11 is the same as above. [ka]

[0123] Examples of the monomer that provides the repeating unit a2 include, but are not limited to, the following: A and R 12 is the same as above. [ka]

[0124] R in the above general formulas (1), (a1) and (a2) ALU , R 11 and R 12 Examples of the acid labile group represented by the formula (I) include those described in JP-A Nos. 2013-80033 and 2013-83821.

[0125] Typical examples of the acid labile group include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0126] In the above general formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 40 carbon atoms, more preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms.

[0127] In the above general formula (AL-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferred.

[0128] In the above general formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0129] In formula (AL-3), R L5 , R L6 and R L7are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L5 , R L6 and R L7 Any two of these may be bonded to each other to form, together with the carbon atoms to which they are bonded, a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0130] When the base polymer contains repeating units a1 and / or a2, the resist composition is a chemically amplified positive resist composition.

[0131] It is also preferred that the base polymer of the resist composition does not contain any acid labile groups, in which case the resist composition is a chemically amplified negative resist composition.

[0132] The base polymer may contain a repeating unit b containing a phenolic hydroxy group as an adhesive group. Examples of monomers that provide the repeating unit b include, but are not limited to, the following. In the following formula, R A is the same as above. [ka]

[0133] [ka]

[0134] [ka]

[0135] The base polymer may contain a repeating unit c containing, as another adhesive group, a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonate ester bond, a carbonyl group, a sulfonyl group, a cyano group, and / or a carboxy group. Examples of monomers that provide the repeating unit c include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0136] [ka]

[0137] [ka]

[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] [ka]

[0142] [ka]

[0143] [ka]

[0144] The base polymer may include repeating units d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Examples of monomers that provide repeating units d include, but are not limited to, the following: [ka]

[0145] The base polymer may include repeat units e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindane, vinylpyridine, or vinylcarbazole.

[0146] The base polymer may contain a repeating unit f derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units f include a repeating unit represented by the following general formula (f1) (hereinafter also referred to as repeating unit f1), a repeating unit represented by the following general formula (f2) (hereinafter also referred to as repeating unit f2), and a repeating unit represented by the following general formula (f3) (hereinafter also referred to as repeating unit f3). The repeating units f1 to f3 may be used alone or in combination of two or more. [ka]

[0147] In the above general formulas (f1) to (f3), R A are each independently a hydrogen atom or a methyl group. 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z11 Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, or may be a combination thereof, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and / or a hydroxy group.

[0148] In the above general formulas (f1) to (f3), R 21 ~R 28 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 11’ ~R 19’Examples of the hydrocarbyl group include the same as those exemplified above. 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, or a halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be any of the rings described above as R 11’ and R 12’ and the sulfur atom to which they are bonded to form a ring, the same rings as those exemplified above can be mentioned.

[0149] In the above general formula (f1), M - is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0150] Other examples of the non-nucleophilic counter ion include a sulfonate ion represented by the following general formula (f1-1) in which the α-position is substituted with a fluorine atom, and a sulfonate ion represented by the following general formula (f1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group. [ka]

[0151] In the above general formula (f1-1), R 31 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (3A') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0152] In the above general formula (f1-2), R 32 is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 6 to 20 carbon atoms, and the hydrocarbyl group and hydrocarbylcarbonyl group may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl moiety of the hydrocarbyl group and hydrocarbylcarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (3A') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0153] Examples of the cation of the monomer that gives the repeating unit f1 include, but are not limited to, the following: A is the same as above. [ka]

[0154] Specific examples of the cation of the monomer that gives the repeating unit f2 or f3 include the same as those exemplified as the cation of the sulfonium salt represented by formula (Cation-1).

[0155] Examples of the anion of the monomer that gives the repeating unit f2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0156] [ka]

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164] [ka]

[0165] [ka]

[0166] [ka]

[0167] Examples of the anion of the monomer that gives the repeating unit f3 include, but are not limited to, those shown below. A is the same as above. [ka]

[0168] [ka]

[0169] The repeating units f1 to f3 function as acid generators. By bonding the acid generator to the polymer main chain, acid diffusion is reduced, preventing a decrease in resolution due to blurring caused by acid diffusion. Furthermore, the uniform dispersion of the acid generator improves LWR and CDU. When a base polymer containing the repeating unit f is used, the addition of an additive-type acid generator, which will be described later, can be omitted.

[0170] In the base polymer, the content ratios of the repeating units a1, a2, b, c, d, e, f1, f2 and f3 are preferably 0≦a1≦0.9, 0≦a2≦0.9, 0≦a1+a2≦0.9, 0≦b≦0.9, 0≦c≦0.9, 0≦d≦0.5, 0≦e≦0.5, 0≦f1≦0.5, 0≦f2≦0.5, 0≦f3≦0.5, 0≦f1+f2+f3≦0.5, and more preferably 0≦a1≦0.8, 0≦a2≦0.8, 0≦a1+a2≦0.8, 0≦f1+a2≦0.8, 0≦f1+f2≦0.8 ≦b≦0.8, 0≦c≦0.8, 0≦d≦0.4, 0≦e≦0.4, 0≦f1≦0.4, 0≦f2≦0.4, 0≦f3≦0.4, and 0≦f1+f2+f3≦0.4 are more preferred, and 0≦a1≦0.7, 0≦a2≦0.7, 0≦a1+a2≦0.7, 0≦b≦0.7, 0≦c≦0.7, 0≦d≦0.3, 0≦e≦0.3, 0≦f1≦0.3, 0≦f2≦0.3, 0≦f3≦0.3, and 0≦f1+f2+f3≦0.3 are even more preferred, provided that a1+a2+b+c+d+f1+f2+f3+e=1.0.

[0171] To synthesize the base polymer, for example, a monomer that provides the repeating unit described above may be polymerized by heating in an organic solvent with the addition of a radical polymerization initiator.

[0172] Examples of organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, and more preferably 5 to 20 hours.

[0173] When a monomer containing a hydroxy group is copolymerized, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid, such as an ethoxyethoxy group, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0174] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by the above-mentioned alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

[0175] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. 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.

[0176] The base polymer preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) using THF as a solvent of 1,000 to 500,000, more preferably 2,000 to 30,000. When the Mw is within the above range, the resist film has good heat resistance and solubility in an alkaline developer.

[0177] Furthermore, if the base polymer has a sufficiently narrow molecular weight distribution (Mw / Mn), there will be no low-molecular-weight or high-molecular-weight polymers, and there will be no risk of foreign matter being observed on the pattern or deterioration of the pattern shape after exposure. As the pattern rules become finer, the effects of Mw and Mw / Mn tend to become greater, so in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the base polymer have a narrow distribution of Mw / Mn of 1.0 to 2.0, and particularly 1.0 to 1.5.

[0178] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0179] [Acid generator] The resist composition of the present invention may contain an acid generator (hereinafter also referred to as an additive acid generator) that generates a strong acid. In this context, the term "strong acid" refers to a compound that has sufficient acidity to cause a deprotection reaction of acid-labile groups in the base polymer in the case of a chemically amplified positive resist composition, and to a compound that has sufficient acidity to cause an acid-induced polarity change reaction or crosslinking reaction in the case of a chemically amplified negative resist composition. By including such an acid generator, the onium salt functions as a quencher, allowing the resist composition of the present invention to function as a chemically amplified positive resist composition or a chemically amplified negative resist composition.

[0180] Examples of the acid generator include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator may be any compound that generates an acid upon exposure to high-energy rays, but is preferably one that generates a sulfonic acid, an imide acid, or a methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of photoacid generators include those described in paragraphs

[0122] to

[0142] of JP 2008-111103 A.

[0181] Furthermore, as the photoacid generator, a sulfonium salt represented by the following general formula (3-1) or an iodonium salt represented by the following general formula (3-2) can also be suitably used. [ka]

[0182] In the above general formulas (3-1) and (3-2), R 101 ~R 105 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 11’~R 19’ Examples of the hydrocarbyl group represented by R include the same as those exemplified above. 101 and R 102 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is the same as that described in the explanation of formula (Cation-1) as R 11’ and R 12’ and the sulfur atom to which they are bonded to form a ring, the same rings as those exemplified above can be mentioned.

[0183] Examples of the cation of the sulfonium salt represented by the above general formula (3-1) include, but are not limited to, the same as those exemplified as the cation of the sulfonium salt represented by formula (Cation-1).

[0184] Examples of the cation of the iodonium salt represented by the above general formula (3-2) include, but are not limited to, the same as those exemplified as the cation of the iodonium salt represented by formula (Cation-2).

[0185] In the above general formulas (3-1) and (3-2), Xa - is an anion selected from the following formulae (3A) to (3D). [ka]

[0186] In the above general formula (3A), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (3A') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0187] The anion represented by formula (3A) is preferably one represented by the following general formula (3A'). [ka]

[0188] In the above general formula (3A'), R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 111 is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. In order to obtain high resolution in the formation of a fine pattern, the hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms.

[0189] R 111 The hydrocarbyl group represented by the formula (I) 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 a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosanyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, Examples include cyclic saturated hydrocarbyl groups having 3 to 38 carbon atoms, such as norbornylmethyl, tricyclodecanyl, tetracyclododecanyl, tetracyclododecanylmethyl, and dicyclohexylmethyl; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms, such as allyl and 3-cyclohexenyl; aryl groups having 6 to 38 carbon atoms, such as phenyl, 1-naphthyl, and 2-naphthyl; aralkyl groups having 7 to 38 carbon atoms, such as benzyl and diphenylmethyl; and groups obtained by combining these.

[0190] In addition, some or all of the hydrogen atoms of these groups 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 carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, resulting in the group containing a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0191] The synthesis of sulfonium salts containing anions represented by the general formula (3A') is described in detail in JP-A Nos. 2007-145797, 2008-106045, 2009-7327, and 2009-258695. Furthermore, the synthesis of sulfonium salts described in JP-A Nos. 2010-215608, 2012-41320, 2012-106986, and 2012-153644 is also preferably used.

[0192] Examples of the anion represented by the general formula (3A) include the same anions as those exemplified as the anion represented by formula (1A) in JP-A-2018-197853.

[0193] In the above general formula (3B), R fb1 and R fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in the general formula (3A') above. 111Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 means that the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to form a ring, in which case, R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0194] In the above general formula (3C), R fc1 , R fc2 and R fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in the general formula (3A') above. 111 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fc1 , R fc2 and R fc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are groups that are bonded together and bond to each other (-CF2-SO2-C - -SO2-CF2-) together to form a ring, in which case, R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0195] In the above general formula (3D), R fd is a hydrocarbyl group having 1 to 40 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 R in formula (3A'). 111Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0196] The synthesis of sulfonium salts containing anions represented by the above general formula (3D) is described in detail in JP-A-2010-215608 and JP-A-2014-133723.

[0197] Examples of the anion represented by the general formula (3D) include the same anions as those exemplified as the anion represented by formula (1D) in JP-A-2018-197853.

[0198] Although the photoacid generator containing the anion represented by the general formula (3D) does not have a fluorine atom at the α-position of the sulfo group, it has two trifluoromethyl groups at the β-position, and therefore has sufficient acidity to cleave the acid labile groups in the base polymer, and can therefore be used as a photoacid generator.

[0199] As the photoacid generator, a compound represented by the following general formula (4) can also be suitably used. [ka]

[0200] In the above general formula (4), R 201 and R 202 R are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 203 is a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. 201 , R 202 and R 203 Any two of these may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be any of the rings described above in the description of general formula (Cation-1) as R 11’ and R 12’ and the sulfur atom to which they are bonded to form a ring, the same rings as those exemplified above can be mentioned.

[0201] R 201 and R 202 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, 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, oxanorbornyl, and tricyclo[5.2.1.0]. 2,6 cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms such as a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, a tert-butylnaphthyl group, an anthracenyl group, and the like; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, these groups may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like.

[0202] R 203The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups having 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, and heptadecane-1,17-diyl group; cyclopentanediyl group, cyclohexene-1,18-diyl group, and the like. Examples of the alkylene groups include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as xanediyl, norbornanediyl, and adamantanediyl; arylene groups having 6 to 30 carbon atoms, such as phenylene, methylphenylene, ethylphenylene, n-propylphenylene, isopropylphenylene, n-butylphenylene, isobutylphenylene, sec-butylphenylene, tert-butylphenylene, naphthylene, methylnaphthylene, ethylnaphthylene, n-propylnaphthylene, isopropylnaphthylene, n-butylnaphthylene, isobutylnaphthylene, sec-butylnaphthylene, and tert-butylnaphthylene; and groups obtained by combining these groups. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the carbon atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the group containing a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. As the heteroatom, an oxygen atom is preferred.

[0203] In the above general formula (4), L Ais a single bond, an ether bond, or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 203 Examples of the hydrocarbylene group represented by the formula (I) include the same as those exemplified above.

[0204] In the above general formula (4), X A , X B , X C and X D are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that X A , X B , X C and X D At least one of the groups is a fluorine atom or a trifluoromethyl group.

[0205] In the above general formula (4), d is an integer of 0-3.

[0206] The photoacid generator represented by the above general formula (4) is preferably one represented by the following general formula (4'). [ka]

[0207] In the above general formula (4'), L A is the same as above. R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 are each independently a hydrogen atom or 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 R in formula (3A'). 111 Examples of the hydrocarbyl group include the same as those exemplified above. Each of x and y is independently an integer of 0 to 5, and z is an integer of 0 to 4.

[0208] Examples of the photoacid generator represented by the general formula (4) above include the same compounds as those exemplified as the photoacid generator represented by formula (2) in JP-A-2017-026980.

[0209] Among the above photoacid generators, those containing anions represented by the general formula (3A') or (3D) are particularly preferred because of their small acid diffusion and excellent solubility in solvents. Also, those represented by formula (4') are particularly preferred because of their extremely small acid diffusion.

[0210] The photoacid generator may also be a sulfonium salt or iodonium salt containing an anion having an aromatic ring substituted with an iodine atom or a bromine atom, such as those represented by the following general formula (5-1) or (5-2): [ka]

[0211] In the above general formulas (5-1) and (5-2), p is an integer that satisfies 1≦p≦3. q and r are integers that satisfy 1≦q≦5, 0≦r≦3, and 1≦q+r≦5. q is preferably an integer that satisfies 1≦q≦3, more preferably 2 or 3. r is preferably an integer that satisfies 0≦r≦2.

[0212] In the above general formulas (5-1) and (5-2), X BI is an iodine atom or a bromine atom, and when p and / or q is 2 or more, they may be the same or different.

[0213] In the above general formulas (5-1) and (5-2), L 1 is a single bond, an ether bond or an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched or cyclic.

[0214] In the above general formulas (5-1) and (5-2), L2 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and represents a (p+1)-valent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0215] In the above general formulas (5-1) and (5-2), R 401 is a hydroxy group, a carboxy 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 hydroxy group, an amino group, or a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, or a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms, which may contain an ether bond, an ester bond, or an amide bond, or —N(R 401A )(R 401B ), -N(R 401C )-C(=O)-R 401D or -N(R 401C )-C(=O)-OR 401D R 401A and R 401B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 401C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy 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. 401Dis an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxy 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 saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbyloxycarbonyl group, saturated hydrocarbylcarbonyl group, and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. When p and / or r is 2 or more, each R 401 may be the same or different from each other.

[0216] Of these, R 401 Examples of the hydroxyl group include -N(R 401C )-C(=O)-R 401D , -N(R 401C )-C(=O)-OR 401D fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, etc. are preferred.

[0217] In the above general formulas (5-1) and (5-2), Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine to form a carbonyl group. 3 and Rf 4 are preferably both fluorine atoms.

[0218] In the above general formulas (5-1) and (5-2), R 402 ~R 406are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 11’ ~R 19’ Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above. In addition, some or all of the hydrogen atoms of these groups may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone ring, a sulfone group, or a sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. 402 and R 403 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is the same as that described for R in the explanation of the general formula (Cation-1) above. 11’ and R 12’ and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, similar to the rings exemplified above.

[0219] Examples of the cation of the sulfonium salt represented by the general formula (5-1) include the same as those exemplified as the cation of the sulfonium salt represented by the general formula (Cation-1) above. Also, examples of the cation of the iodonium salt represented by the formula (5-2) include the same as those exemplified as the cation of the iodonium salt represented by the general formula (Cation-2) above.

[0220] Specific examples of the anion of the onium salt represented by the general formula (5-1) or (5-2) include, but are not limited to, the following: BI is the same as above. [ka]

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[0243] When the resist composition of the present invention contains an additive acid generator, the amount thereof is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, relative to 100 parts by mass of the base polymer. When the base polymer contains any of the repeating units f1 to f3 and / or when the resist composition of the present invention contains an additive acid generator, it can function as a chemically amplified resist composition.

[0244] [Organic solvents] The resist composition of the present invention may further contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the components described above and the components described below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] and

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

[0245] In the resist composition of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, and more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvents may be used alone or in combination of two or more.

[0246] As explained above, the onium salt of the present invention exhibits sufficient solubility in organic solvents, and therefore, the resist composition of the present invention does not involve concerns about precipitation of the acid diffusion controller.

[0247] [Other ingredients] In addition to the above-mentioned components, the resist composition of the present invention may contain a surfactant, a dissolution inhibitor, a crosslinking agent, a quencher other than the onium salt of the present invention (hereinafter referred to as "other quenchers"), a water repellency improver, an acetylene alcohol, etc.

[0248] Examples of the surfactant include those described in paragraphs

[0165] and

[0166] of JP 2008-111103 A. Adding a surfactant can further improve or control the coatability of the resist composition. When the resist composition of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 10 parts by mass per 100 parts by mass of the base polymer. The surfactants may be used alone or in combination of two or more.

[0249] When the resist composition of the present invention is a positive resist composition, the incorporation of a dissolution inhibitor can further increase the difference in dissolution rate between exposed and unexposed areas, thereby further improving resolution. Examples of the dissolution inhibitor include compounds having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, containing two or more phenolic hydroxy groups in the molecule, in which the hydrogen atoms of the phenolic hydroxy groups have been substituted with acid labile groups at a rate of 0 to 100 mol % overall, and compounds containing carboxy groups in the molecule, in which the hydrogen atoms of the carboxy groups have been substituted with acid labile groups at an average rate of 50 to 100 mol % overall. Specific examples include compounds in which the hydroxyl groups or carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid have been substituted with acid labile groups. These compounds are described, for example, in paragraphs

[0155] to

[0178] of JP 2008-122932 A.

[0250] When the resist composition of the present invention is a positive resist composition and contains the above-mentioned dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, and more preferably 5 to 40 parts by mass, relative to 100 parts by mass of the base polymer. The above-mentioned dissolution inhibitors may be used alone, or two or more types may be used in combination.

[0251] On the other hand, when the resist composition of the present invention is a negative resist, a negative pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds, urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds, such as alkenyloxy groups, all of which are substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. These may be used as additives or may be introduced as pendant groups into polymer side chains. Hydroxy-containing compounds may also be used as crosslinking agents.

[0252] Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0253] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated, or a mixture thereof.

[0254] Examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound of tetramethylolguanamine in which 1 to 4 methylol groups are methoxymethylated, or a mixture thereof; tetramethoxyethylguanamine, tetraacyloxyguanamine, a compound of tetramethylolguanamine in which 1 to 4 methylol groups are acyloxymethylated, or a mixture thereof; and the like.

[0255] Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril have been methoxymethylated or a mixture thereof, and a compound in which 1 to 4 methylol groups of tetramethylol glycoluril have been acyloxymethylated or a mixture thereof.

[0256] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound of tetramethylol urea in which 1 to 4 methylol groups are methoxymethylated, or a mixture thereof, and tetramethoxyethyl urea.

[0257] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0258] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0259] Examples of the compound containing the alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0260] When the resist composition of the present invention is a negative resist composition and contains the above-mentioned crosslinking agent, the content thereof is preferably 0.1 to 50 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The above-mentioned crosslinking agents may be used alone, or two or more types may be used in combination.

[0261] Examples of the other quenchers include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. Particularly preferred are the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond, and compounds having a carbamate group described in Japanese Patent No. 3790649 A. Addition of such basic compounds can, for example, further suppress the diffusion rate of acid in the resist film or correct the shape.

[0262] Other quenchers include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids and carboxylic acids that are not fluorinated at the α-position, as described in JP-A-2008-158339. Sulfonic acids, imide acids, or methide acids that are fluorinated at the α-position are necessary for deprotecting the acid labile group of a carboxylic acid ester, and salt exchange with an onium salt that is not fluorinated at the α-position releases sulfonic acids or carboxylic acids that are not fluorinated at the α-position. Sulfonic acids and carboxylic acids that are not fluorinated at the α-position do not undergo deprotection reactions, and therefore function as quenchers.

[0263] Other examples of quenchers include the polymer-type quenchers described in JP 2008-239918 A. These quenchers enhance the rectangularity of the resist pattern by orienting on the surface of the resist film. Polymer-type quenchers also have the effect of preventing pattern film loss and rounding of the pattern top when a protective film for immersion lithography is applied.

[0264] When the resist composition of the present invention contains another quencher, the content thereof is preferably 0 to 5 parts by mass, and more preferably 0 to 4 parts by mass, relative to 100 parts by mass of the base polymer. The other quenchers may be used alone or in combination of two or more.

[0265] The water repellency improver improves the water repellency of the resist film surface and can be used in immersion lithography without a top coat. Preferred examples of the water repellency improver include polymers containing fluorinated alkyl groups and polymers containing a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue, with those exemplified in JP-A-2007-297590 and JP-A-2008-111103 being more preferred. The water repellency improver must be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, polymers containing repeating units containing an amino group or an amine salt are highly effective in preventing acid evaporation during post-exposure baking (PEB) and preventing poor hole pattern opening after development. When the resist composition (chemically amplified resist material) of the present invention contains the water repellency improver, the content thereof is preferably 0 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more types.

[0266] Examples of the acetylene alcohols include those described in paragraphs

[0179] to

[0182] of JP 2008-122932 A. When the chemically amplified resist composition of the present invention contains the acetylene alcohols, the content thereof is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more.

[0267] [Pattern formation method] When the resist composition of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied.For example, the pattern formation method of the present invention includes the steps of forming a resist film on a substrate using the resist composition (chemically amplified resist material) of the present invention, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

[0268] An example of the pattern forming method of the present invention will be described below.

[0269] First, the resist composition of the present invention is applied to a substrate for integrated circuit production (e.g., Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating, etc.) or a substrate for mask circuit production (e.g., Cr, CrO, CrON, MoSi2, SiO2, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., to a coating thickness of 0.01 to 2 μm. This is then pre-baked on a hot plate, preferably at 60 to 150°C for 10 seconds to 30 minutes, more preferably at 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0270] Next, the resist film is exposed to high-energy radiation. Examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, electron beam (EB), extreme ultraviolet radiation (EUV) with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When ultraviolet radiation, far ultraviolet radiation, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation are used as the high-energy radiation, the exposure dose is preferably 1 to 200 mJ / cm, either directly or using a mask for forming a desired pattern. 2 approximately, more preferably 10 to 100 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 300 μC / cm 2 approximately, more preferably 0.5 to 200 μC / cm 2The resist composition of the present invention is particularly suitable for fine patterning using high-energy rays such as KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, and synchrotron radiation, and is particularly suitable for fine patterning using KrF excimer laser light, ArF excimer laser light, EB, or EUV with a wavelength of 3 to 15 nm.

[0271] After exposure, PEB may or may not be performed on a hot plate or in an oven, preferably at 30 to 150° C. for 10 seconds to 30 minutes, more preferably at 50 to 120° C. for 30 seconds to 20 minutes.

[0272] After exposure or PEB, the exposed resist film is developed using a developer of an alkaline aqueous solution containing 0.1 to 10% by mass, preferably 2 to 5% by mass, of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or the like, for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying, to form the desired pattern. In the case of a positive resist composition, the irradiated portion dissolves in the developer, while the unexposed portion does not, forming the desired positive pattern on the substrate. In the case of a negative resist composition, the opposite occurs to the positive resist composition; the irradiated portion becomes insoluble in the developer, while the unexposed portion dissolves.

[0273] A negative pattern can also be obtained by organic solvent development using a positive resist composition containing a base polymer containing an acid labile group. Examples of the developer used in this case include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, and ethyl crotonate. Examples of organic solvents include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. These organic solvents may be used alone or in combination of two or more.

[0274] After the development is completed, it is preferable to rinse the resist film. As the rinse liquid, a solvent that is miscible with the developer but does not dissolve the resist film is preferable. As such a solvent, for example, an alcohol having 3 to 10 carbon atoms, an ether compound having 8 to 12 carbon atoms, an alkane, alkene, alkyne, or aromatic solvent having 6 to 12 carbon atoms is preferably used.

[0275] Examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. Examples of the alcohol include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

[0276] Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0277] Examples of the alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, and cyclononane. Examples of the alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, and cyclooctene. Examples of the alkynes having 6 to 12 carbon atoms include hexyne, heptine, and octyne.

[0278] Examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0279] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used.

[0280] The developed hole or trench pattern can also be shrunk using thermal flow, RELACS, or DSA. A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds. Excess shrink agent is removed, and the hole pattern is shrunk.

[0281] The pattern forming method of the present invention uses the resist composition of the present invention, and therefore can form a resist film that is excellent in sensitivity and resolution, has small LWR of a line pattern, and CDU of a hole pattern and a dot pattern, and further suppresses swelling during development and collapse of the resist pattern, enabling precise microfabrication. [Example]

[0282] The present invention will be specifically explained below by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The apparatuses used are as follows. MALDI TOF-MS: JEOL S3000

[0283] [1] Synthesis of onium salts [Example 1-1] Synthesis of SQ-1 [ka]

[0284] (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, sodium hydride (purity 55% by mass, 4.8 g) was suspended in THF (60 ml), and a solution consisting of 1-isopropylcyclopentanol (14.1 g) and THF (15 ml) was added dropwise. After the dropwise addition, the mixture was heated under reflux for 4 hours to prepare a metal alkoxide. Then, the starting material SM-1 (24.7 g) was added dropwise, and the mixture was heated under reflux and aged for 18 hours. The reaction solution was cooled in an ice bath, and the reaction was quenched with water (100 ml). The target product was extracted with a solvent consisting of toluene (100 ml) and hexane (100 ml), and the product was subjected to standard aqueous work-up. After the solvent was distilled off, the product was purified by silica gel chromatography to obtain 28.8 g of intermediate In-1 as a colorless oil (yield 81%).

[0285] (2) Synthesis of intermediate In-2 Under a nitrogen atmosphere, intermediate In-1 (28.8 g) was aged for 24 hours at an internal temperature of 100°C in a solution consisting of 25% by mass aqueous sodium hydroxide (38.9 g) and water (100 ml). After aging, the reaction solution was cooled, and toluene (500 ml) was added, followed by azeotropic dehydration five times. The residue after azeotropic dehydration was recrystallized from hexane, yielding 18.0 g of intermediate In-2 as white crystals (yield 56%).

[0286] (3) Synthesis of onium salt SQ-1 Under a nitrogen atmosphere, intermediate In-2 (7.9 g) and raw material SM-2 (6.5 g) were dissolved in methylene chloride (50 g) and water (40 g) and stirred for 20 minutes. The reaction mixture was separated, and the organic layer was collected and subjected to standard aqueous work-up. The solvent was then distilled off to obtain 11.0 g of onium salt SQ-1 as a colorless oil (yield 87%).

[0287] The results of TOF-MS of the onium salt SQ-1 are shown below. MALDI TOF-MS: POSITIVE M + 261(C 18 H 13 S + equivalent) NEGATIVE M - 373(C 15 H 18 IO3 - equivalent)

[0288] [Examples 1-2 to 1-9] Synthesis of SQ-2 to SQ-9 Various onium salts were synthesized by various organic synthesis reactions. The structures of the onium salts used in the chemically amplified resist compositions are shown below. [ka]

[0289] [2] [Synthesis example] Synthesis of base polymers (P-1 to P-5) Each monomer was combined and copolymerized in THF, which was used as a solvent. The resulting copolymer was crystallized in methanol, washed repeatedly with hexane, and then isolated and dried to obtain the base polymers (P-1 to P-5) with the following compositions. 1 Mw and Mw / Mn were confirmed by H-NMR and GPC (solvent: THF, standard: polystyrene). [ka]

[0290] [ka]

[0291] [3] [Examples 2-1 to 2-20, Comparative Examples 1-1 to 1-12] Preparation of resist composition (1) Preparation of resist composition Resist compositions were prepared by filtering solutions containing dissolved components according to the compositions shown in Tables 1 and 2 through a 0.2 μm filter. The resist compositions of Examples 2-1 to 2-18 and Comparative Examples 1-1 to 1-10 were positive-working, while the resist compositions of Examples 2-19 and 2-20 and Comparative Examples 1-11 and 1-12 were negative-working.

[0292] In Table 1, the components are as follows: Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol)

[0293] Photoacid generators: PAG-1 to PAG-5 [ka]

[0294] Blend quencher: bQ-1, bQ-2 [ka]

[0295] Comparison quenchers: cSQ-1 to cSQ-4 [ka]

[0296] [Table 1]

[0297] [Table 2]

[0298] [4] EUV Lithography Evaluation (1) [Examples 3-1 to 3-20, Comparative Examples 2-1 to 2-12] Each of the chemically amplified resist compositions (R-1 to R-20, CR-1 to CR-12) shown in Tables 1 and 2 was spin-coated onto a Si substrate on which a 20-nm-thick silicon-containing spin-on hard mask SHB-A940 (silicon content: 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a 50-nm-thick resist film. This was then exposed to an LS pattern with an on-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) while varying the exposure dose and focus (exposure dose pitch: 1 mJ / cm). 2 After exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 3 and 4. Paddle development was then performed for 30 seconds with a 2.38% by mass TMAH aqueous solution, followed by rinsing with a surfactant-containing rinse solution and spin drying. Positive patterns were obtained in Examples 3-1 to 3-18 and Comparative Examples 2-1 to 2-10. Negative patterns were obtained in Examples 3-19 and 3-20 and Comparative Examples 2-11 and 2-12.

[0299] The obtained LS patterns were observed with a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, exposure latitude (EL), LWR, depth of focus (DOF), and tilt limit were evaluated according to the following methods. The results are shown in Tables 3 and 4.

[0300] [Sensitivity evaluation] The optimum exposure dose E for obtaining an LS pattern with a line width of 18 nm and a pitch of 36 nm op (mJ / cm 2 The smaller this value, the higher the sensitivity.

[0301] [EL Rating] EL (unit: %) was calculated from the exposure amount formed within a range of ±10% (16.2 to 19.8 nm) of the 18 nm space width in the above LS pattern using the following formula. The larger this value, the better the performance. EL(%)=(|E1-E2| / E op ) x 100 E1: Optimal exposure dose for LS pattern with line width of 16.2 nm and pitch of 36 nm E2: Optimal exposure dose for LS pattern with line width of 19.8 nm and pitch of 36 nm E op : Optimal exposure dose to produce LS pattern with line width of 18nm and pitch of 36nm

[0302] [LWR rating] E op The dimensions of the LS pattern obtained by irradiation at 10 points in the longitudinal direction of the line were measured, and the LWR was calculated as three times the standard deviation (σ) (3σ). The smaller this value, the less roughness and the more uniform the line width pattern obtained.

[0303] [DOF evaluation] For the evaluation of the depth of focus, the focus range formed within a range of ±10% (16.2 to 19.8 nm) of the 18 nm dimension in the LS pattern was determined. The larger this value, the wider the depth of focus.

[0304] [Line pattern collapse limit evaluation] The line dimension of the LS pattern at each exposure dose at the optimum focus was measured at 10 locations in the longitudinal direction. The narrowest line dimension obtained without collapse was taken as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0305] [Table 3]

[0306] [Table 4]

[0307] From the results shown in Tables 3 and 4, it was confirmed that in Examples 3-1 to 3-18 in which a positive pattern was formed, the optimum exposure dose was generally smaller and the sensitivity was better than in Comparative Examples 2-1 to 2-10 in which a similar positive pattern was formed. Similarly, it was confirmed that in Examples 3-19 and 3-20 in which a negative pattern was formed, the optimum exposure dose was smaller and the sensitivity was better than in Comparative Examples 2-11 and 2-12 in which a similar negative pattern was formed.

[0308] Furthermore, from the results shown in Tables 3 and 4, it was confirmed that in Examples 3-1 to 3-18 in which a positive pattern was formed, EL was generally larger than that in Comparative Examples 2-1 to 2-10 in which a similar positive pattern was formed. Similarly, it was confirmed that in Examples 3-19 and 3-20 in which a negative pattern was formed, EL was generally larger than that in Comparative Examples 2-11 and 2-12 in which a similar negative pattern was formed.

[0309] Furthermore, from the results shown in Tables 3 and 4, it was confirmed that in Examples 3-1 to 3-18 in which positive patterns were formed, the LWR was smaller, the DOF was larger, and the tilt limit dimension was smaller than in Comparative Examples 2-1 to 2-10 in which similar positive patterns were formed. Similarly, from the results shown in Tables 3 and 4, it was confirmed that in Examples 3-19 and 3-20 in which negative patterns were formed, the LWR was smaller, the DOF was larger, and the tilt limit dimension was smaller than in Comparative Examples 2-11 and 2-12 in which similar negative patterns were formed.

[0310] That is, from the results shown in Tables 3 and 4, it was found that the chemically amplified resist composition containing the quencher (acid diffusion controller) of the present invention had good sensitivity and excellent EL, LWR, and DOF in both positive and negative tones. Furthermore, it was confirmed that the collapse limit value was small and that the composition was resistant to pattern collapse even in the formation of fine patterns.

[0311] On the other hand, the quencher does not contain the onium salt of the present invention, but instead has an anion structure represented by -OR in the above general formula (1). ALUAny of onium salts cSQ-1 to cSQ-3 containing no group and no iodine atom, or onium salt cS Q It was found that resist compositions CR-1 to CR-12 containing any of the above-mentioned compounds No. 1 to No. 4 were inferior in LWR and DOF and were more susceptible to pattern collapse than the resist composition examples of the present invention.

[0312] [5] EUV Lithography Evaluation (2) [Examples 4-1 to 4-20, Comparative Examples 3-1 to 3-12] Each resist composition shown in Tables 1 and 2 was spin-coated onto a Si substrate with a 20 nm thick silicon-containing spin-on hard mask SHB-A940 (43% silicon by mass) manufactured by Shin-Etsu Chemical Co., Ltd., and pre-baked at 100°C for 60 seconds using a hot plate to produce a 60 nm thick resist film. The resist film was then exposed to light using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, a hole pattern mask with a 44 nm pitch on the wafer and a +20% bias). PEB was performed on a hot plate for 60 seconds at the temperatures listed in Tables 5 and 6, and development was performed for 30 seconds with a 2.38% by mass TMAH aqueous solution to produce 22 nm hole patterns in Examples 4-1 to 4-18 and Comparative Examples 3-1 to 3-10, and 22 nm dot patterns in Examples 4-19, 4-20, and Comparative Examples 3-11 and 3-12.

[0313] Using a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, the exposure dose when holes or dots were formed with a dimension of 22 nm was measured and used as the sensitivity. The dimensions of 50 holes or dots at this time were also measured, and the CDU was calculated by multiplying the standard deviation (σ) by three (3σ). The results are shown in Tables 5 and 6.

[0314] [Table 5]

[0315] [Table 6]

[0316] From the results shown in Tables 5 and 6, it was confirmed that Examples 4-1 to 4-18 in which hole patterns were formed exhibited smaller CDUs than Comparative Examples 3-1 to 3-10 in which hole patterns were also formed, and were superior in CDU. dot It was confirmed that the CDU was smaller than that of Comparative Examples 3-11 and 3-12 in which patterns were formed, and that the CDU was excellent. That is, the results shown in Tables 5 and 6 confirm that the chemically amplified resist composition containing the quencher (acid diffusion controller) of the present invention has good sensitivity in both positive and negative tones and is excellent in CDU.

[0317] On the other hand, the quencher does not contain the onium salt of the present invention, but is -OR in the above general formula (1). ALU Any of onium salts cSQ-1 to cSQ-3 containing an onium anion that does not contain a group and does not contain an iodine atom, or onium salt cS Q It was found that resist compositions CR-1 to CR-12 containing any of the above-mentioned compounds were inferior in CDU to the resist composition examples of the present invention.

[0318] Furthermore, from the preparation of resist compositions R-1 to R-20 containing the components shown in Table 1 until their subsequent use in the above examples, no precipitation of the quencher was observed in any of the resist compositions.

[0319] The present specification includes the following aspects. [1] An onium salt represented by the following general formula (1): [ka] (In the formula, R ALU represents a tertiary ether, a tertiary carbonate, or an acetal, which may have a heteroatom, formed together with the adjacent oxygen atom. I represents an iodine atom. Ra is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. n1 is an integer of 0 or 1. n2 and n3 are integers of 1 or 2. When n2 and n3 are 1, I and -OR ALU are bonded to adjacent carbon atoms. Also, when either or both of n2 and n3 are 2, I and -OR ALU are bonded to adjacent carbon atoms. n4 is an integer from 0 to 3. When n4 ≥ 2, multiple R a may be bonded to each other to form a ring structure together with the carbon atoms to which they are attached. + represents an onium cation. [2] Furthermore, R in the general formula (1) ALU The onium salt according to [1], characterized in that the structure is represented by the following general formula (ALU-1) or (ALU-2): [ka] (In formula (ALU-1), R 21’ , R 22’ , and R 23’ are each independently a hydrocarbyl group having 1 to 12 carbon atoms which may have a heteroatom, and R 21’ , R 22’ , and R 23’ Any two of these may be bonded to each other to form a ring. t is an integer of 0 or 1. In formula (ALU-2), R 24’ , and R 25’ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. 26’ is a hydrocarbyl group having 1 to 20 carbon atoms, or R 24’ or R 25’ and bond to each other, and the carbon atoms to which they are bonded and X a may form a heterocyclic group having 3 to 20 carbon atoms together with X. Furthermore, -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. * represents a bond with the adjacent oxygen atom.) [3] Furthermore, Z in the general formula (1) +is an onium cation represented by any one of the following general formulae (Cation-1) to (Cation-3): [ka] (In formulas (Cation-1) to (Cation-3), R 11’ ~R 19’ are each independently a linear, branched or cyclic hydrocarbyl group having 1 to 30 carbon atoms, which may contain a heteroatom and may be saturated or unsaturated. [4] An acid diffusion controller comprising the onium salt according to any one of [1] to [3]. [5] A resist composition comprising the acid diffusion controller according to [4]. [6] The resist composition according to [5], further comprising an acid generator that generates an acid. [7] The resist composition according to [6], wherein the acid generator generates a sulfonic acid, an imide acid, or a methide acid. [8] The resist composition according to any one of [5] to [7], further comprising an organic solvent. [9] The resist composition according to any one of [5] to [8], further comprising a base polymer.

[10] The resist composition according to [9], wherein the base polymer contains a repeating unit represented by the following general formula (a1) and / or a repeating unit represented by the following general formula (a2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 Y is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. 2 is a single bond or an ester bond. 3is a single bond, an ether bond, or an ester bond. 11 and R 12 are each independently an acid labile group. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 14 represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of whose carbon atoms may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4, provided that 1≦a+b≦5.

[11] The resist composition according to any one of [5] to

[10] , wherein the resist composition is a chemically amplified positive resist composition.

[12] The resist composition according to any one of [5] to [9], wherein the resist composition is a chemically amplified negative resist composition.

[13] The resist composition according to [9], wherein the base polymer does not contain an acid labile group.

[14] The resist composition according to [9],

[10] or

[13] , wherein the base polymer further contains at least one repeating unit selected from the repeating units represented by the following general formulas (f1) to (f3): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 11 Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group.2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 R is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, or may be a combination thereof, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and / or a hydroxy group. 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 and R 26 and R 27 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. - is a non-nucleophilic counterion.

[15] The resist composition according to any one of [5] to

[14] , further comprising a surfactant.

[16] A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist composition according to any one of [5] to

[15] ; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

[17] The pattern forming method according to

[16] , wherein the high-energy beam is KrF excimer laser beam, ArF excimer laser beam, electron beam, or extreme ultraviolet ray having a wavelength of 3 to 15 nm.

[0320] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An onium salt characterized by being represented by the following general formula (1): 【Chemical 1】 (In the formula, R ＡＬＵ represents a tertiary ether, a tertiary carbonate, or an acetal, which may have a heteroatom, formed together with the adjacent oxygen atom. I represents an iodine atom. ａ is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. n1 is an integer of 0 or 1. n2 and n3 are integers of 1 or 2. When n2 and n3 are 1, I and —O—R ＡＬＵ are bonded to adjacent carbon atoms. When either or both of n2 and n3 is 2, I and —O—R ＡＬＵ are bonded to adjacent carbon atoms. n4 is an integer of 0 to 3. When n4 is 2 or more, multiple R ａ may be bonded to each other to form a ring structure together with the carbon atoms to which they are attached. ＋ represents an onium cation.

2. Furthermore, R in the general formula (1) ＡＬＵ The onium salt according to claim 1, characterized in that the structure of the onium salt is represented by the following general formula (ALU-1) or (ALU-2): 【Chemistry 2】 (In formula (ALU-1), R ２１’ , R ２２’ , and R ２３’ are each independently a hydrocarbyl group having 1 to 12 carbon atoms which may have a heteroatom, and R ２１’ , R ２２’ , and R ２３’ Any two of these may be bonded to each other to form a ring. t is an integer of 0 or 1. In formula (ALU-2), R ２４’ , and R ２５’ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. ２６’ is a hydrocarbyl group having 1 to 20 carbon atoms, or R ２４’ or R ２５’ and the carbon atoms to which they are bonded and X ａ may form a heterocyclic group having 3 to 20 carbon atoms together with the —CH ２ - may be replaced by -O- or -S-. ａ represents an oxygen atom or a sulfur atom. * represents a bond with an adjacent oxygen atom.)

3. Furthermore, Z in the general formula (1) ＋ is an onium cation represented by any one of the following general formulas (Cation-1) to (Cation-3): 【Chemistry 3】 (In formulas (Cation-1) to (Cation-3), R １１’ ~R １９’ are each independently a linear, branched or cyclic hydrocarbyl group having 1 to 30 carbon atoms, which may contain a heteroatom and may be saturated or unsaturated.

4. An acid diffusion controller comprising the onium salt according to any one of claims 1 to 3.

5. A resist composition comprising the acid diffusion controller according to claim 4.

6. 6. The resist composition according to claim 5, further comprising an acid generator that generates an acid.

7. 7. The resist composition according to claim 6, wherein the acid generator generates a sulfonic acid, an imide acid, or a methide acid.

8. 6. The resist composition according to claim 5, further comprising an organic solvent.

9. 6. The resist composition according to claim 5, further comprising a base polymer.

10. 10. The resist composition according to claim 9, wherein the base polymer contains a repeating unit represented by the following general formula (a1) and / or a repeating unit represented by the following general formula (a2): 【Chemistry 4】 (In the formula, R Ａ are each independently a hydrogen atom or a methyl group. １ Y is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. ２ is a single bond or an ester bond. ３ is a single bond, an ether bond, or an ester bond. １１ and R １２ are each independently an acid labile group. １３ is a fluorine atom, a trifluoromethyl group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms. １４ represents a single bond or an alkanediyl group having 1 to 6 carbon atoms, some of whose carbon atoms may be substituted with ether bonds or ester bonds; a is 1 or 2; and b is an integer of 0 to 4, provided that 1≦a+b≦5.

11. 6. The resist composition according to claim 5, wherein the resist composition is a chemically amplified positive resist composition.

12. 6. The resist composition according to claim 5, wherein the resist composition is a chemically amplified negative resist composition.

13. 10. The resist composition according to claim 9, wherein the base polymer does not contain an acid labile group.

14. 10. The resist composition according to claim 9, wherein the base polymer further comprises at least one repeating unit selected from the group consisting of repeating units represented by the following general formulas (f1) to (f3): 【Chemistry 5】 (In the formula, R Ａ are each independently a hydrogen atom or a methyl group. １ represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, an ester bond, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z １１ -, -C(=O)-O-Z １１ - or -C(=O)-NH-Z １１ - is. Z １１ represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. ２ is a single bond or an ester bond. ３ is a single bond, -Z ３１ -C(=O)-O-, -Z ３１ -O- or -Z ３１ -O-C(=O)-. Z ３１ represents a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z ４ is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. ５ represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O-Z ５１ -, -C(=O)-O-Z ５１ - or -C(=O)-NH-Z ５１ - is. Z ５１ R is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, or may be a combination thereof, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom, and / or a hydroxy group. ２１ ~R ２８ are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. ２３ and R ２４ and or R ２６ and R ２７ and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. － is a non-nucleophilic counterion.)

15. 6. The resist composition according to claim 5, further comprising a surfactant.

16. 6. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist composition according to claim 5; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

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

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