Monomer, polymer, chemically amplified resist composition, and pattern forming process

Abstract

To provide a monomer used in a chemically amplified resist composition which, in photolithography using high-energy radiation, exhibits excellent solvent solubility, high sensitivity, and high contrast, and also offers superior lithographic performance such as exposure latitude (EL) and LWR, as well as superior pattern profile and etch resistance after development; a polymer obtained from the monomer; a chemically amplified resist composition; and a pattern forming process using the chemically amplified resist composition.SOLUTION: The present invention provides a monomer represented by formula (A), a polymer comprising a repeating unit derived from the monomer, and a chemically amplified resist composition comprising a base polymer including the polymer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a monomer, a polymer, a chemically amplified resist composition and a patterning method. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming finer at a rapid pace. This is because 5G high-speed communications and artificial intelligence (AI) are becoming more widespread, and high-performance devices are needed to process these. The most advanced miniaturization technology is extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, which is used to mass-produce 5 nm node devices. Furthermore, studies are underway to use EUV lithography for next-generation 3 nm node devices and the next-next generation 2 nm node devices.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem. In order to ensure resolution in fine patterns with processing dimensions of 45 nm or less, it has been proposed that control of acid diffusion is important in addition to improving dissolution contrast, as has been proposed in the past (Non-Patent Document 1). However, since chemically amplified resist compositions increase sensitivity and contrast by acid diffusion, if one tries to suppress acid diffusion to the maximum extent by lowering the post-exposure bake (PEB) temperature or shortening the time, the sensitivity and contrast will decrease significantly.

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

[0005] It is effective to suppress acid diffusion by adding an acid generator that generates a bulky acid. Therefore, it has been proposed to incorporate repeating units derived from an onium salt having a polymerizable unsaturated bond 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 a polymerizable unsaturated bond that generate specific sulfonic acids. Patent Document 2 proposes sulfonium salts in which sulfonic acids are directly linked to the main chain.

[0006] As miniaturization advances, resistance to pattern collapse during fine pattern formation and resistance to etching processes are particularly important for positive resist compositions. Patent documents 3 and 4 describe polymers that use acenaphthylene having a rigid structure as a polymerizable group and contain structural units having polar groups such as lactone structures, acidic groups such as hexafluoroisopropanol structures and carboxy groups, and acid labile groups such as acetal structures and tertiary ether structures in their partial structures. Patent document 5 also proposes an organic solvent-developable negative resist composition that uses a polymer that contains acenaphthylene units having a chain-like tertiary ester structure as a structural unit.

[0007] Although the performance of these resist compositions has been improved to some extent, they have not yet achieved satisfactory results. In order to meet the demand for further miniaturization, there is a need to develop acid labile monomers that have good acid elimination reactivity with acids and are excellent in resistance to pattern collapse after fine pattern formation and in the etching process. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2006-045311 A [Patent Document 2] JP 2006-178317 A [Patent Document 3] International Publication No. 2022 / 186059 [Patent Document 4] International Publication No. 2023 / 054126 [Patent Document 5] Patent No. 5793389 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above circumstances, and has an object to provide a monomer for use in a chemically amplified resist composition which has excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance such as exposure tolerance (EL) and LWR, as well as pattern shape and etching resistance after development, particularly in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), EUV, etc.; a polymer obtained by using the monomer; a chemically amplified resist composition; and a pattern formation method using the chemically amplified resist composition. [Means for solving the problem]

[0010] As a result of intensive research into achieving the above-mentioned object, the present inventors have found that a monomer having an acenaphthylene skeleton as a polymerizable group and having a tertiary ester-type acid labile group bonded thereto, or a polymer containing a repeating unit derived from said monomer, has excellent solvent solubility, and that a chemically amplified resist composition using said polymer as a base polymer has high sensitivity and high contrast, is excellent in lithography performance such as EL and LWR, and is extremely effective in suppressing pattern collapse during the formation of fine patterns and in etching resistance after development, which has led to the completion of the present invention.

[0011] That is, the present invention provides the following monomer, polymer, chemically amplified resist composition, and pattern forming method. 1. A monomer represented by the following formula (A): [ka] (In the formula, a1 is 1 or 2, and a2 is an integer of 0 to 4. R Aeach independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. When a2 ≧2, multiple R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L A is a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. X L represents a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. R L1 , R L2 and R L3 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom, R L1 , R L2 and R L3 Any two of R may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L1 , R L2 and R L3 At least one of has at least one structure selected from a multiple bond, an alicyclic ring, and an aromatic ring. 2. A monomer according to formula 1, which is represented by the following formula (A1): [ka] (In the formula, a2, R A , R 1 , L A , X L and R L1 ~R L3 is the same as above.) 3. The monomer of formula 2, which is represented by the following formula (A2). [ka] (In the formula, a2, R A , R 1 and R L1 ~RL3 is the same as above.) 4. A polymer containing a repeating unit derived from any one of the monomers 1 to 3. 5. The polymer of 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (a1) and a repeating unit represented by the following formula (a2): [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-OX 11 - or -C(=O)-NH-X 11 -, and the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. R 11 represents a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. AL 1 and A.L. 2 are each independently an acid labile group. a3 is an integer from 0 to 4. 6. The polymer of 4 or 5, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (b1) and a repeating unit represented by the following formula (b2): [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). R 22 represents a halogen atom, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. b1 is an integer from 1 to 4. b2 is an integer from 0 to 4, provided that 1≦b1+b2≦5. 7. The polymer of any one of 4 to 6, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (c1), a repeating unit represented by the following formula (c2), a repeating unit represented by the following formula (c3), and a repeating unit represented by the following formula (c4): [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 is a single bond or a phenylene group. Z 2 is **-C(=O)-OZ 21 -,**-C(=O)-NH-Z 21 -or**-OZ 21 -It is. 21 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 -It is. 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. Z 4 each independently represents a single bond, ***-Z 41 -C(=O)-O-, ***-C(=O)-NH-Z 41 -or***-OZ 41 -It is. It is. Z 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. Z 5 are each independently a single bond, ****-Z 51 -C(=O)-O-, ****-C(=O)-NH-Z 51 -or****-OZ 51 -It is. 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. Z 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-OZ 61 -, *-C(=O)-N(H)-Z 61 -or*-OZ 61 -It is. 61represents 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, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * represents a bond to a carbon atom in the main chain. ** represents Z 1 *** represents a bond with Z 3 **** represents a bond with Z 4 Represents a bond with . R 31 and R 32 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. c1 and c2 each independently represent an integer of 0 to 3. 8. A chemically amplified resist composition comprising a base polymer containing any one of the polymers 4 to 7, and an organic solvent. 9. The chemically amplified resist composition of 8 further comprising a quencher. 10. The chemically amplified resist composition of 8 or 9 further comprising a photoacid generator. 11. Any one of the chemically amplified resist compositions of 8 to 10, further comprising a surfactant. 12. A pattern forming method comprising the steps of forming a resist film on a substrate using any one of the chemically amplified resist compositions according to any one of claims 8 to 11, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer. 13. The pattern formation method according to 12, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, EB or EUV having a wavelength of 3 to 15 nm. Effect of the Invention

[0012] When a pattern is formed using a chemically amplified resist composition containing as a base polymer a polymer obtained using the monomer of the present invention, it is possible to form a resist pattern that has high contrast and good sensitivity, is excellent in lithography performance such as DOF ​​and LWR, and is suppressed from pattern collapse. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [monomer] The monomer of the present invention is represented by the following formula (A). [ka]

[0014] In formula (A), a1 is an integer of 1 or 2, and from the viewpoint of raw material procurement, is preferably 1. a2 is an integer of 0 to 4, and is preferably 0, 1 or 2, and more preferably 0 or 1.

[0015] In formula (A), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred.

[0016] In formula (A), R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an icosyl group; a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclo Examples of the alkyl groups include cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a hexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group, and a naphthyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these groups. Of these, aryl groups are preferred. 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 -CH2- of 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 anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0017] When a2 ≧ 2, multiple R 1may be bonded to each other to form a ring together with the carbon atom to which they are bonded. Examples of the ring formed in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring. In addition, some or all of the hydrogen atoms in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of -CH2- in the ring may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the ring 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, or the like.

[0018] In formula (A), L A is a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. Of these, a single bond, an ether bond or an ester bond is preferred.

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

[0020] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a heteroatom, represented by the following formula, include, but are not limited to, those shown below. In the following formula, * indicates that the adjacent L A and represents a bond to -C(=O)-. [ka]

[0021] [ka]

[0022] [ka]

[0023] [ka]

[0024] Of these, X L -0~X L -22 and X L -47~X L -58 is preferred.

[0025] In formula (A), R L1 , R L2 and R L3 are each independently a hydrocarbyl group having 1 to 30 carbon atoms, preferably 1 to 10 carbon atoms, which may contain a heteroatom; R L1 , R L2 and R L3 Any two of R may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L1 , R L2 and R L3 At least one of R has at least one structure selected from a multiple bond, an alicyclic ring, and an aromatic ring. L1 , R L2 and R L3 At least one of them is preferably a hydrocarbyl group having 2 to 30 carbon atoms and containing a multiple bond, a hydrocarbyl group having 3 to 30 carbon atoms and containing an alicyclic structure, or a hydrocarbyl group having 6 to 30 carbon atoms and containing an aromatic ring structure. In addition, -CH2- contained in the hydrocarbyl group may be substituted with -O- or -S-.

[0026] In formula (A), -C(R L1 )(R L2 )(R L3Specific examples of the acid labile group represented by the formula (I) include, but are not limited to, those shown below. In the following formula, * represents a bond to the adjacent oxygen atom. [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] The monomer represented by formula (A) is preferably one represented by the following formula (A1). [ka] (In the formula, a2, R A , R 1 , L A , X L and R L1 ~R L3 is the same as above.)

[0038] The monomer represented by formula (A1) is preferably one represented by the following formula (A2). [ka] (In the formula, a2, R A , R 1 and R L1 ~R L3 is the same as above.)

[0039] Specific examples of the monomer represented by formula (A) include, but are not limited to, those shown below. [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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[0062]

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[0063]

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[0064]

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[0065]

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[0066]

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[0067]

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[0068]

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[0069]

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[0070]

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[0071]

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[0072]

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[0073]

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[0074]

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[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] The monomer of the present invention can be synthesized by a known method, for example, the method shown in the following scheme. [ka] (In the formula, a1, a2, R A , R 1 , L A , X L , R L1 ~R L3 is the same as above.)

[0080] The first reaction is the conversion of a carboxylic acid raw material (SM-1) to the corresponding carboxylic acid chloride to obtain (Pre-A).

[0081] The raw material (SM-1) can be synthesized according to a known method or can be obtained as a commercial product. The raw material (SM-1) is suspended in an aromatic hydrocarbon solvent such as toluene or a halogen-containing solvent such as methylene chloride, and oxalyl chloride or thionyl chloride is added dropwise to prepare a carboxylic acid chloride. The reaction can be accelerated by adding a small amount of N,N-dimethylformamide during preparation. In order to efficiently prepare the carboxylic acid chloride, it is preferable to appropriately heat the solvent from room temperature to about the boiling point of the solvent. The reaction time is usually about 2 to 4 hours, although it is desirable to follow the reaction by gas chromatography (GC) or silica gel thin layer chromatography (TLC) in terms of yield and complete the reaction. The reaction solution can be concentrated to obtain the carboxylic acid chloride (Pre-A), which is a precursor of the target product, and if necessary, it can be purified according to a conventional method such as distillation, chromatography, or recrystallization.

[0082] The second reaction is a reaction to obtain the target monomer (A) by esterification of the target precursor carboxylic acid chloride (Pre-A) with a tertiary alcohol.

[0083] The esterification reaction can be carried out according to a known recipe. The carboxylic acid chloride (Pre-1), which is the target precursor, and the corresponding tertiary alcohol are dissolved in a hydrocarbon solvent such as toluene or hexane, or a polar aprotic solvent such as tetrahydrofuran or acetonitrile, or a halogen-containing solvent such as methylene chloride or 1,2-dichloroethane, and an organic base such as triethylamine or pyridine is added dropwise to carry out the reaction. The reaction can be accelerated by adding 4-dimethylaminopyridine during the reaction. In order to improve the reaction conversion rate, the reaction can be carried out by heating, etc., as necessary. The reaction time is usually about 0.5 to 3 hours, although it is desirable to follow the reaction by gas chromatography (GC) or silica gel thin layer chromatography (TLC) and complete the reaction in terms of yield. The target monomer (A) can be obtained from the reaction mixture by a normal aqueous work-up, and if necessary, it can be purified according to a normal method such as distillation, chromatography, or recrystallization.

[0084] The above-mentioned production method is merely an example, and the production method of the monomer of the present invention is not limited thereto.

[0085] The structural feature of the monomer of the present invention is that it has a rigid acenaphthylene as a polymerizable group and has a tertiary ester type acid labile group bonded thereto. The tertiary ester type acid labile group in the exposed portion undergoes a deprotection reaction with the acid generated from the acid generator, generating a carboxyl group. The tertiary ester structure is preferably one having a cyclic structure or one having multiple bonds. In the case of a cyclic structure, the reactivity to acid is improved by the driving force of eliminating steric hindrance, and in the case of a multiple bond, the reactivity to acid is improved by the driving force of the generation of benzyl cations or allyl cations. This improves the contrast between the exposed portion and the unexposed portion, and in the case of a positive resist using an alkaline developer, the exposed portion in which the deprotection reaction has progressed has improved affinity for alkaline development, and is effectively removed by the developer. A tertiary ester structure consisting of a saturated chain alkyl group without a cyclic structure or multiple bonds is not very reactive to acid, since it is difficult to obtain the above effect. In addition, the acenaphthylene structure of the polymerizable group improves the glass transition temperature (Tg) of the polymer because the condensed aromatic ring has rigidity. Since resistance to an alkaline developer is required in the unexposed area, the polymer rigidified by the acenaphthylene structure exhibits resistance to the developer, suppresses peeling of the resist pattern from the substrate and collapse of the resist pattern, and exhibits excellent etching resistance in the subsequent etching step. Due to these synergistic effects, a chemically amplified resist composition containing a polymer obtained using the monomer of the present invention has high dissolution contrast, is excellent in LWR of a line pattern and CDU of a hole pattern, enables pattern formation that is resistant to pattern collapse, and also has excellent etching resistance. Therefore, the monomer of the present invention is suitable as a material for a resist composition for fine pattern formation, particularly as a material for a positive resist composition.

[0086] [polymer] The polymer of the present invention is obtained by using a monomer represented by formula (A). That is, the polymer of the present invention contains a repeating unit derived from the monomer represented by formula (A) (hereinafter, also referred to as repeating unit A). The repeating unit A is represented by the following formula (A'). [ka] (In the formula, a1, a2, R A , R 1 , R L1 ~R L3 , L A and X L is the same as above.)

[0087] The repeating unit A may be used alone or in combination of two or more kinds.

[0088] The base polymer may further include a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0089] In formulas (a1) and (a2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-OX 11 - or -C(=O)-NH-X 11 -, and the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. 11 X is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. 2is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 11 represents a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. a3 represents an integer of 0 to 4.

[0090] In the formulas (a1) and (a2), AL 1 and A.L. 2 are each independently an acid labile group. Examples of the acid labile group include those described in JP-A-2013-80033 and JP-A-2013-83821.

[0091] Typically, the acid labile group includes those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0092] In formulas (AL-1) and (AL-2), R L11 and R L12 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, and 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 preferably has 1 to 20 carbon atoms.

[0093] In formula (AL-1), k is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0094] In formula (AL-2), R L13 and R L14are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and 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. L12 , R L13 and R L14 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 preferable, and an alicyclic ring is particularly preferable.

[0095] In formula (AL-3), R L15 , R L16 and R L17 are each independently a hydrocarbyl group having 1 to 20 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. L15 , R L16 and R L17 Any two of these may be bonded to each other to form, together with the carbon atom 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.

[0096] Specific examples of the repeating unit a1 include, but are not limited to, those shown below. A and A.L. 1 is the same as above. [ka]

[0097] [ka]

[0098] [ka]

[0099] Specific examples of the repeating unit a2 include, but are not limited to, those shown below. A and A.L. 2 is the same as above. [ka]

[0100] [ka]

[0101] The polymer preferably further contains a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0102] In formulas (b1) and (b2), R A Y each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 R is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-). 22is a halogen atom, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. b1 is an integer of 1 to 4. b2 is an integer of 0 to 4, with the proviso that 1≦b1+b2≦5.

[0103] Specific examples of the repeating unit b1 include, but are not limited to, those shown below. A is the same as above. [ka]

[0104] [ka]

[0105] [ka]

[0106] [ka]

[0107] [ka]

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] Specific examples of the repeating unit b2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] As the repeating unit b1 or b2, in ArF lithography, those having a lactone ring as a polar group are particularly preferred, while in KrF lithography, EB lithography and EUV lithography, those having a phenol moiety are preferred.

[0125] The polymer may further include at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (c1) (hereinafter also referred to as repeating unit c1), a repeating unit represented by the following formula (c2) (hereinafter also referred to as repeating unit c2), a repeating unit represented by the following formula (c3) (hereinafter also referred to as repeating unit c3), and a repeating unit represented by the following formula (c4) (hereinafter also referred to as repeating unit c4). These repeating units function as photoacid generators bonded to the polymer main chain. [ka]

[0126] In formulas (c1) to (c4), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1is a single bond or a phenylene group. 2 is **-C(=O)-OZ 21 -,**-C(=O)-NH-Z 21 -or**-OZ 21 -It is. 21 Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 -It is. 31 Z is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 4 each independently represents a single bond, ***-Z 41 -C(=O)-O-, ***-C(=O)-NH-Z 41 -or***-OZ 41 -It is. It is. Z 41 Z is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 5 are each independently a single bond, ****-Z 51 -C(=O)-O-, ****-C(=O)-NH-Z 51 -or****-OZ 51 -It is. 51 Z is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-OZ 61 -, *-C(=O)-N(H)-Z 61 -or*-OZ 61 -It is. 61represents 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, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond to a carbon atom in the main chain. ** represents Z 1 *** represents a bond with Z 3 **** represents a bond with Z 4 Represents a bond with .

[0127] Z 21 , Z 31 and Z 61 The aliphatic hydrocarbylene group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane- Examples of the alkanediyl groups include a 2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2-diyl group, and a hexane-1,6-diyl group; cycloalkanediyl groups such as a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, and a cyclohexanediyl group; and groups obtained by combining these groups.

[0128] Z 41 and Z 51 The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include, but are not limited to, those shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0129] In formula (c1), R 31 and R 32are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and thienyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, with aryl groups being preferred. 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 -CH2- of 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 fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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 anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0130] Also, R 31 and R 32 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 the ring represented by R ct1 and R ct2 can be bonded to form a ring together with the sulfur atom to which they are bonded, similar to the examples given above.

[0131] Specific examples of the cation of the repeating unit c1 include, but are not limited to, those shown below. A is the same as above. [ka]

[0132] [ka]

[0133] [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] [ka]

[0138] In formula (c1), M -is a non-nucleophilic counter ion. The non-nucleophilic counter ion is preferably a halide ion, a sulfonate anion, an imide anion, or a methide anion. Specific examples of the halide ion include a chloride ion and a bromide ion. Specific examples of the sulfonate anion (sulfonate ion) include fluoroalkylsulfonate ions such as a triflate ion, a 1,1,1-trifluoroethanesulfonate ion, and a nonafluorobutanesulfonate ion; arylsulfonate ions such as a tosylate ion, a benzenesulfonate ion, a 4-fluorobenzenesulfonate ion, and a 1,2,3,4,5-pentafluorobenzenesulfonate ion; and alkylsulfonate ions such as a mesylate ion and a butanesulfonate ion. Specific examples of the imide anion (imide ion) include a bis(trifluoromethylsulfonyl)imide ion, a bis(perfluoroethylsulfonyl)imide ion, and a bis(perfluorobutylsulfonyl)imide ion. Specific examples of the methide acid anion (methide ion) include tris(trifluoromethylsulfonyl)methide ion, tris(perfluoroethylsulfonyl)methide ion, and the like.

[0139] Other examples of the non-nucleophilic counter ion include anions represented by any of the following formulas (c1-1) to (c1-4). [ka]

[0140] In formula (c1-1), 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 fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0141] The anion represented by formula (c1-1) is preferably one represented by the following formula (c1-1-1): [ka]

[0142] In formula (c1-1-1), Q 1 and Q 2 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, and in order to improve the solvent solubility, it is preferable that at least one of them is a trifluoromethyl group. m is an integer of 0 to 4, and is particularly preferably 1. R fa1 is a hydrocarbyl group having 1 to 35 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. From the viewpoint of obtaining high resolution in the formation of a fine pattern, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

[0143] In formula (c1-1-1), R fa1The hydrocarbyl group having 1 to 35 carbon atoms 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 35 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-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 icosyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, a norbornyl group, and the like. Examples of the alkyl groups include cyclic saturated hydrocarbyl groups having 3 to 35 carbon atoms, such as an arylmethyl group, a tricyclodecyl group, a tetracyclododecyl group, a tetracyclododecylmethyl group, and a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 35 carbon atoms, such as a 2-propenyl group and a 3-cyclohexenyl group; aryl groups having 6 to 35 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, and a 9-fluorenyl group; aralkyl groups having 7 to 35 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these.

[0144] 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 -CH2- of 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 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 anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of hydrocarbyl groups containing a heteroatom 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.

[0145] In formula (c1-1-1), L a1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond, and from the viewpoint of synthesis, an ether bond or an ester bond is preferable, and an ester bond is more preferable.

[0146] Specific examples of the anion represented by formula (c1-1) include, but are not limited to, those shown below. In the following formula, Q 1 is the same as above, and Ac is an acetyl group. [ka]

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] [ka]

[0155] [ka]

[0156] In formula (c1-2), 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 fa1 Examples of the hydrocarbyl group represented by the formula 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 are bonded to each other and the group to which they are bonded (-CF2-SO2-N - -SO2-CF2-) may 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.

[0157] In formula (c1-3), 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 fa1 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fc1 , R fc2 and Rfc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are bonded to each other and the groups to which they are bonded (-CF2-SO2-C - -SO2-CF2-) may 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.

[0158] In formula (c1-4), 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 fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0159] Specific examples of the anion represented by formula (c1-4) include, but are not limited to, those shown below. [ka]

[0160] [ka]

[0161] Further examples of the non-nucleophilic counter ion include an anion having an aromatic ring substituted with an iodine atom or a bromine atom. Specific examples of such an anion include those represented by the following formula (c1-5): [ka]

[0162] In formula (c1-5), x is an integer satisfying 1≦x≦3. y and z are integers satisfying 1≦y≦5, 0≦z≦3, and 1≦y+z≦5. y is preferably an integer satisfying 1≦y≦3, and more preferably 2 or 3. z is preferably an integer satisfying 0≦z≦2.

[0163] In formula (c1-5), X BI is an iodine atom or a bromine atom, and when x and / or y are 2 or more, they may be the same or different.

[0164] In formula (c1-5), L 11 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.

[0165] In formula (c1-5), L 12 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when x is 1, and represents a (x+1)-valent linking group having 1 to 20 carbon atoms when x is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0166] In formula (c1-5), R fe is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or 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 a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or feA )(R feB ), -N(R feC )-C(=O)-R feD Or -N(R feC )-C(=O)-OR feD R feA and R feBR are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may 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. feD is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a 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 hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When x and / or z is 2 or more, each R fe may be the same or different from each other.

[0167] Of these, R fe Examples of the hydroxyl group include -N(R feC )-C(=O)-R feD , -N(R feC )-C(=O)-OR feD , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like are preferred.

[0168] In formula (c1-5), Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, at least one of which is a fluorine atom or a trifluoromethyl group. 11 and Rf 12 may combine to form a carbonyl group. 13 and Rf 14 are preferably both fluorine atoms.

[0169] Examples of the anion represented by formula (c1-5) include, but are not limited to, those shown below. In the following formula, X BI is the same as above. [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179]

change

[0180]

change

[0181]

change

[0182]

change

[0183]

change

[0184]

change

[0185]

change

[0186]

change

[0187]

change

[0188]

change

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] As the non-nucleophilic counter ion, a fluorobenzenesulfonate anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, an anion having a mechanism of decomposition by acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-70692, an anion having a cyclic ether group as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935, and an anion as described in Japanese Patent Application Publication No. 2018-92159 can also be used.

[0193] Further, as the non-nucleophilic counter ion, anions of bulky benzenesulfonic acid derivatives not containing fluorine atoms, as described in JP 2006-276759 A, JP 2015-117200 A, JP 2016-65016 A, and JP 2019-202974 A, and benzenesulfonic acid anions and alkylsulfonic acid anions not containing fluorine atoms bonded to aromatic groups containing iodine atoms, as described in Japanese Patent No. 6645464, can also be used.

[0194] Further examples of the non-nucleophilic counter ion include an anion of bissulfonic acid described in JP 2015-206932 A, an anion of sulfonamide or sulfonimide having a sulfonic acid on one side and a different sulfonic acid on the other side described in WO 2020 / 158366 A, and an anion of sulfonic acid on one side and carboxylic acid on the other described in JP 2015-24989 A.

[0195] In formulas (c2) and (c3), L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, from the viewpoint of synthesis, an ether bond, an ester bond or a carbonyl group is preferred, and an ester bond or a carbonyl group is more preferred.

[0196] In formula (c2), Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, each of Rf is preferably a fluorine atom. 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Of these, Rf 3 and Rf 4 At least one of these is preferably a trifluoromethyl group.

[0197] In formula (c3), Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 Of these, Rf 5 and Rf 6 At least one of these is preferably a trifluoromethyl group.

[0198] In formulae (c2) and (c3), c1 and c2 each independently represent an integer of 0 to 3, with 1 being preferred.

[0199] Specific examples of the anion of the repeating unit c2 include, but are not limited to, those shown below. A is the same as above, and Me is a methyl group. [ka]

[0200] [ka]

[0201] [ka]

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] [ka]

[0206] [ka]

[0207] [ka]

[0208] Specific examples of the anion of the repeating unit c3 include, but are not limited to, those shown below. A is the same as above. [ka]

[0209] [ka]

[0210] [ka]

[0211] [ka]

[0212] [ka]

[0213] [ka]

[0214] [ka]

[0215] [ka]

[0216] Specific examples of the anion of the repeating unit c4 include, but are not limited to, those shown below. A is the same as above. [ka]

[0217] In formulas (c2) to (c4), A +is an onium cation. Examples of the onium cation include an ammonium cation, a sulfonium cation, and an iodonium cation, and the onium cation is preferably a sulfonium cation or an iodonium cation.

[0218] The onium cation is preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka]

[0219] In formulas (cation-1) and (cation-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0220] R ct1 ~R ct5 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0221] R ct1 ~R ct5The 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 30 carbon atoms, such as a vinyl group, a 1-propenyl group, a 2-propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group; aralkyl groups having 7 to 30 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these, with an aryl group being preferred. In addition, a portion 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 a portion of -CH2- of 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 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 anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0222] Also, R ct1 and R ct2 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 ring structure include those represented by the following formulas: [ka] (In the formula, the dashed line represents R ct3 It is a bond with .)

[0223] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0224] [ka]

[0225] [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] [ka]

[0232] [ka]

[0233]

change

[0234]

change

[0235]

change

[0236]

change

[0237]

change

[0238]

change

[0239]

change

[0240]

change

[0241]

change

[0242]

change

[0243]

change

[0244] [ka]

[0245] [ka]

[0246] [ka]

[0247] [ka]

[0248] [ka]

[0249] [ka]

[0250] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0251] [ka]

[0252] Specific structures of the repeating units c1 to c4 include any combination of the above-mentioned anions and cations.

[0253] Of the repeating units c1 to c4, the repeating units c2, c3 and c4 are preferred from the viewpoint of controlling acid diffusion, the repeating units c2 and c4 are more preferred from the viewpoint of the acid strength of the generated acid, and the repeating unit c2 is more preferred from the viewpoint of solvent solubility.

[0254] The base polymer may further include a repeating unit having a structure in which a hydroxy group is protected by an acid labile group (hereinafter, also referred to as repeating unit d). The repeating unit d is not particularly limited as long as it has one or more structures in which a hydroxy group is protected, and the protecting group is decomposed by the action of an acid to generate a hydroxy group, but is preferably represented by the following formula (d1). [ka]

[0255] In formula (d1), R A is the same as above. R 41 R is a (e+1)-valent hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom. 42 is an acid labile group. e is an integer of 1 to 4.

[0256] In formula (d1), R 42 The acid labile group represented by the formula (I) may be any group that can be deprotected by the action of an acid to generate a hydroxy group. 42 Although the structure is not particularly limited, an acetal structure, a ketal structure, an alkoxycarbonyl group, an alkoxymethyl group represented by the following formula (d2), and the like are preferred, and an alkoxymethyl group represented by the following formula (d2) is particularly preferred. [ka] (In the formula, * represents a bond. 43 is a hydrocarbyl group having 1 to 15 carbon atoms.

[0257] R 42Examples of the acid-labile group represented by the formula, the alkoxymethyl group represented by the formula (d2), and the repeating unit d include those similar to those exemplified in the description of the repeating unit d described in JP-A-2020-111564.

[0258] The base polymer may further contain a repeating unit e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or a derivative thereof. Specific examples of the monomer that gives the repeating unit e include, but are not limited to, those shown below.

Chemical formula

[0259] The base polymer may further contain a repeating unit f derived from indane, vinylpyridine, or vinylcarbazole.

[0260] In the polymer of the present invention, the content ratios of the repeating units A, a1, a2, b1, b2, c1 to c4, d, e, and f are preferably 0 < A ≤ 0.8, 0 ≤ a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ b1 ≤ 0.6, 0 ≤ b2 ≤ 0.6, 0 ≤ c1 ≤ 0.4, 0 ≤ c2 ≤ 0.4, 0 ≤ c3 ≤ 0.4, 0 ≤ c4 ≤ 0.4, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.3, and 0 ≤ f ≤ 0.3, and more preferably 0 < A ≤ 0.5, 0 ≤ a1 ≤ 0.5, 0 ≤ a2 ≤ 0.5, 0 ≤ b1 ≤ 0.5, 0 ≤ b2 ≤ 0.5, 0 ≤ c1 ≤ 0.3, 0 ≤ c2 ≤ 0.3, 0 ≤ c3 ≤ 0.3, 0 ≤ c4 ≤ 0.3, 0 ≤ d ≤ 0.3, 0 ≤ e ≤ 0.3, and 0 ≤ f ≤ 0.3.

[0261] The weight average molecular weight (Mw) of the polymer is preferably 1000 to 500000, more preferably 3000 to 100000. If Mw is within this range, sufficient etching resistance is obtained, and there is no risk of a decrease in resolution due to an inability to ensure a difference in dissolution rate before and after exposure. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using THF or N,N-dimethylformamide (DMF) as a solvent.

[0262] Furthermore, since the influence of Mw / Mn on the molecular weight distribution of the polymer tends to increase as the pattern rule becomes finer, in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that Mw / Mn is a narrow dispersion of 1.0 to 2.0. Within the above range, there is little low or high molecular weight polymer, and there is no risk of foreign matter being found on the pattern or the shape of the pattern being deteriorated after exposure.

[0263] To synthesize the polymer, for example, a monomer that provides the repeating unit described above may be polymerized in an organic solvent by adding a radical polymerization initiator and heating the resulting mixture.

[0264] Examples of the organic solvent used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% based on the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, and more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0265] The polymerization initiator may be added to the monomer solution and then fed to the reaction vessel, or an initiator solution may be prepared separately from the monomer solution and then fed to the reaction vessel independently. Since there is a possibility that the polymerization reaction proceeds due to radicals generated from the initiator during the waiting time, resulting in the formation of a super-polymer, it is preferable to prepare the monomer solution and the initiator solution independently and dropwise feed them from the viewpoint of quality control. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization. In addition, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination to adjust the molecular weight. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% based on the total amount of monomers to be polymerized.

[0266] In the case of a monomer containing a hydroxy group, 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.

[0267] When hydroxystyrene or hydroxyvinylnaphthalene is copolymerized, hydroxystyrene or hydroxyvinylnaphthalene may be polymerized by heating with another monomer in an organic solvent after adding a radical polymerization initiator, or acetoxystyrene or acetoxyvinylnaphthalene may be used and, after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to give polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0268] As the base for the alkaline hydrolysis, ammonia water, triethylamine, etc. can be used. 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.

[0269] The amount of each monomer in the monomer solution may be appropriately set so as to obtain the preferred content ratio of the repeating units described above.

[0270] Regarding the polymer obtained by the above-mentioned production method, a reaction solution obtained by a polymerization reaction may be used as the final product, or a powder obtained through a purification step such as a reprecipitation method in which a polymerization solution is added to a poor solvent to obtain a powder may be handled as the final product. However, from the viewpoint of work efficiency and quality stabilization, it is preferable to handle a polymer solution obtained by dissolving the powder obtained by the purification step in a solvent as the final product.

[0271] Specific examples of the solvent used in this case include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether. ethers such as ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, etc.; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling alcohol solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, etc.; and mixed solvents thereof.

[0272] The concentration of the polymer in the polymer solution is preferably from 0.01 to 30% by mass, more preferably from 0.1 to 20% by mass.

[0273] The reaction solution or polymer solution is preferably filtered through a filter, which is effective in stabilizing the quality since it can remove foreign matter or gel that may cause defects.

[0274] The material of the filter used in the filter filtration includes fluorocarbon, cellulose, nylon, polyester, and hydrocarbon materials, but in the filtration process of the resist composition, a filter formed of a fluorocarbon, so-called Teflon (registered trademark), a hydrocarbon such as polyethylene or polypropylene, or nylon is preferred. The pore size of the filter can be appropriately selected according to the target cleanliness, but is preferably 100 nm or less, more preferably 20 nm or less. In addition, these filters may be used alone, or multiple filters may be used in combination. The filtration method may be to pass the solution only once, but it is more preferable to circulate the solution and perform filtration multiple times. The filtration process can be performed in any order and number of times in the polymer production process, but it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0275] [Chemically amplified resist composition] [(A) Base polymer] The chemically amplified resist composition of the present invention comprises (A) a base polymer containing the above-mentioned polymer.

[0276] In the base polymer of component (A), the above-mentioned polymers may be used alone or in combination of two or more different polymers having different composition ratios, Mw and / or Mw / Mn. In addition to the above-mentioned polymers, the base polymer (A) may contain a hydrogenated ring-opening metathesis polymer, and the one described in JP-A-2003-66612 can be used.

[0277] [(B) Organic solvent] The chemically amplified resist composition of the present invention contains an organic solvent as component (B). There are no particular limitations on the organic solvent as long as it is capable of dissolving the components described above and below. Examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ketoalcohols such as DAA; ethers such as PGME, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono tert-butyl ether acetate; lactones such as GBL; and mixed solvents thereof.

[0278] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixed solvents thereof are preferred, as they have particularly excellent solubility for the base polymer of component (A).

[0279] In the chemically amplified resist composition of the present invention, the content of the organic solvent (B) is preferably 200 to 5000 parts by mass, and more preferably 400 to 3500 parts by mass, relative to 80 parts by mass of the base polymer (A). The organic solvent (B) may be used alone or in combination of two or more kinds.

[0280] [(C) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (C). In the present invention, the quencher refers to a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, thereby preventing the acid from diffusing into unexposed areas and forming a desired pattern.

[0281] The (C) quencher includes an onium salt represented by the following formula (C1) or (C2). [ka]

[0282] In formula (C1), R q1 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. q2 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom.

[0283] R q1 Specific examples of the hydrocarbyl group having 1 to 40 carbon atoms represented by the formula (1) include alkyl groups having 1 to 40 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, a tricyclo[5.2.1.0 2,6] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as a decyl group or an adamantyl group; and aryl groups having 6 to 40 carbon atoms, such as a phenyl group, a naphthyl group or an anthracenyl group. Some or all of the hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms or halogen atoms, and some of the -CH2- in the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms or nitrogen atoms, so that the hydrocarbyl groups may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0284] R q2 Specific examples of the hydrocarbyl group represented by the formula: q1 In addition to the specific examples of the substituents given above, examples include fluorinated saturated hydrocarbyl groups such as a trifluoromethyl group and a trifluoroethyl group, and fluorinated aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0285] Specific examples of the anion of the onium salt represented by formula (C1) include, but are not limited to, those shown below. [ka]

[0286] [ka]

[0287] [ka]

[0288] [ka]

[0289] Specific examples of the anion of the onium salt represented by formula (C2) include, but are not limited to, those shown below. [ka]

[0290] [ka]

[0291] [ka]

[0292] In formulas (C1) and (C2), Mq + is an onium cation. The onium cation is preferably a sulfonium cation represented by the above formula (cation-1), an iodonium cation represented by the above formula (cation-2), or an ammonium cation represented by the following formula (cation-3). [ka]

[0293] In formula (cation-3), R ct6 ~R ct9 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. ct6 and R ct7 and may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded. As the hydrocarbyl group, R ct1 ~R ct5 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0294] Specific examples of the ammonium cation represented by formula (cation-3) include, but are not limited to, those shown below. [ka]

[0295] Specific examples of the onium salt represented by formula (C1) or (C2) include any combination of the above-mentioned anions and cations. These onium salts can be easily prepared by ion exchange reaction using known organic chemical methods. For the ion exchange reaction, refer to, for example, JP-A-2007-145797.

[0296] The onium salt represented by formula (C1) or (C2) acts as a quencher in the chemically amplified resist composition of the present invention. This is because each counter anion of the onium salt is a conjugate base of a weak acid. The onium salt represented by formula (C1) or (C2) functions as a quencher when used in combination with an onium salt-type photoacid generator having a conjugate base of a strong acid such as a sulfonic acid whose α-position is fluorinated as a counter anion. That is, when an onium salt that generates a strong acid such as a sulfonic acid whose α-position is fluorinated and an onium salt that generates a weak acid such as a non-fluorinated sulfonic acid or carboxylic acid are mixed and used, when the strong acid generated from the photoacid generator by irradiation with high energy rays collides with an onium salt having an unreacted weak acid anion, the weak acid is released by salt exchange to generate an onium salt having a strong acid anion. In this process, the strong acid is exchanged for a weak acid with a lower catalytic activity, and the acid is apparently deactivated, thereby controlling acid diffusion. In the present invention, a weak acid refers to a compound having an acidity that is not sufficient to deprotect the acid labile group in the acid labile group-containing unit used in the base polymer, and a strong acid refers to a compound having an acidity sufficient to cause a deprotection reaction of the acid labile group.

[0297] In addition, as the quencher (C), an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent No. 6,848,776, an onium salt having a sulfonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent No. 6,583,136 and JP-A-2020-200311, and an onium salt having an iodonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent No. 6,274,755 can also be used.

[0298] Here, when the photoacid generator that generates a strong acid is an onium salt, the strong acid generated by irradiation with high energy rays can be exchanged for a weak acid as described above, but on the other hand, it is considered that the weak acid generated by irradiation with high energy rays collides with the onium salt that generates the unreacted strong acid and is unlikely to undergo salt exchange. This is due to the phenomenon that the onium cation is more likely to form an ion pair with the anion of the strong acid.

[0299] When the chemically amplified resist composition of the present invention contains an onium salt represented by formula (C1) or (C2) as the quencher (C), the content is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 80 parts by mass of the base polymer (A). If the onium salt type quencher of the component (C) is within the above range, the resolution is good and the sensitivity is not significantly reduced, which is preferable. The onium salt represented by formula (C1) or (C2) may be used alone or in combination of two or more.

[0300] The chemically amplified resist composition of the present invention may contain a nitrogen-containing compound as a quencher (C). The nitrogen-containing compound of component (C) may be a primary, secondary or tertiary amine compound described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly an amine compound having a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group or a sulfonate ester bond. In addition, a compound in which a primary or secondary amine is protected with a carbamate group may be used, such as the compound described in JP-A-3790649.

[0301] In addition, a sulfonium salt of sulfonic acid having a nitrogen-containing substituent may be used as the nitrogen-containing compound. Such a compound functions as a quencher in the unexposed area, and functions as a so-called photodegradable base in the exposed area, losing the quenching ability by neutralization with the acid generated by itself. By using a photodegradable base, the contrast between the exposed area and the unexposed area can be further enhanced. For example, JP-A-2009-109595 and JP-A-2012-46501 can be referred to for the photodegradable base.

[0302] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as a quencher (C), the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, relative to 80 parts by mass of the base polymer (A). The nitrogen-containing compound may be used alone or in combination of two or more kinds.

[0303] [(D) Photoacid generator] The chemically amplified resist composition of the present invention may contain a photoacid generator as component (D). There are no particular limitations on the photoacid generator, so long as it is a compound that generates a strong acid upon exposure to high-energy rays.

[0304] Suitable photoacid generators include those represented by the following formula (D1) or (D2). [ka]

[0305] In formulas (D1) and (D2), R 101 ~R 105 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 101 , R 102 and R 103 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. As the hydrocarbyl group, R ct1~R ct5 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0306] Specific examples of the cation of the sulfonium salt represented by formula (D1) include the same as those exemplified as the sulfonium cation represented by formula (cation-1). Specific examples of the cation of the iodonium salt represented by formula (D2) include the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0307] In formulas (D1) and (D2), Xa - is an anion of a strong acid. Examples of the anion of a strong acid include those represented by any of formulas (c1-1) to (c1-5).

[0308] As the photoacid generator (D), a compound represented by the following formula (D3) is also preferred. [ka]

[0309] In formula (D3), R 201 and R 202 R is each independently 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 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0310] R 201 and R 202The hydrocarbyl group having 1 to 30 carbon atoms 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group or an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a decyl group, and an adamantyl group; aryl groups having 6 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, and an anthracenyl group; and groups obtained by combining these. 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 -CH2- of 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 anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0311] R 203The hydrocarbylene group having 1 to 30 carbon atoms represented by the following formula 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 a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, a tetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, a hexadecane-1,16-diyl group, and a heptadecane-1,17-diyl group; Examples of such aryl groups include cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as amantanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group; and arylene groups, such as a phenylene group, a methylphenylene group, an ethylphenylene group, a n-propylphenylene group, an isopropylphenylene group, a n-butylphenylene group, an isobutylphenylene group, a sec-butylphenylene group, a tert-butylphenylene group, a naphthylene group, a methylnaphthylene group, an ethylnaphthylene group, a n-propylnaphthylene group, an isopropylnaphthylene group, a n-butylnaphthylene group, an isobutylnaphthylene group, a sec-butylnaphthylene group, and a tert-butylnaphthylene group. In addition, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the hydrocarbylene 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 anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. As the heteroatom, an oxygen atom is preferable.

[0312] In formula (D3), L 11is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, or 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.

[0313] In formula (D3), X a , X b , X c and X d are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. a , X b , X c and X d At least one of the groups is a fluorine atom or a trifluoromethyl group.

[0314] The photoacid generator represented by formula (D3) is preferably one represented by the following formula (D3'). [ka]

[0315] In formula (D3'), L 11 is the same as above. X e R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 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 fa1 Examples of the hydrocarbyl group represented by the formula: embedded image are the same as those exemplified above. Each of p and q independently represents an integer of 0 to 5, and r represents an integer of 0 to 4.

[0316] Examples of the photoacid generator represented by formula (D3) include the same as those exemplified as the photoacid generator represented by formula (2) in JP2017-26980A.

[0317] Among the photoacid generators, those containing an anion represented by formula (c1-1-1) or (c1-4) are particularly preferred because of their small acid diffusion and excellent solubility in solvents. Also, those represented by formula (D3') are particularly preferred because of their extremely small acid diffusion.

[0318] When the chemically amplified resist composition of the present invention contains a photoacid generator (D), the content is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, relative to 80 parts by mass of the base polymer (A). If the amount of the photoacid generator (D) added is within the above range, the resolution is good and there is no risk of problems with foreign matter occurring after development of the resist film or during stripping, which is preferable. The photoacid generator (D) may be used alone or in combination of two or more types. In addition, when the base polymer contains any of the repeating units c1 to c4 (i.e., when it is a polymer-bound photoacid generator), the incorporation of the photoacid generator (D) may be omitted.

[0319] [(E) Surfactant] The chemically amplified resist composition of the present invention may further contain a surfactant as component (E). The surfactant (E) is preferably a surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or poorly soluble in water and an alkaline developer. Examples of such surfactants include those described in JP-A-2010-215608 and JP-A-2011-16746.

[0320] Among the surfactants described in the above publication, preferred surfactants that are insoluble or poorly soluble in water and alkaline developers include FC-4430 (manufactured by 3M), Surflon (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Olfine (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and an oxetane ring-opening polymer represented by the following formula (surf-1): [ka]

[0321] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), regardless of the above description. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the aliphatic group include divalent ones such as ethylene group, 1,4-butylene group, 1,2-propylene group, 2,2-dimethyl-1,3-propylene group, and 1,5-pentylene group, and examples of trivalent or tetravalent ones include the following: [ka] (In the formula, the dashed lines represent bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0322] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferable.

[0323] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer of 0 to 3, n is an integer of 1 to 4, and the sum of n and m is the valence of R, which is an integer of 2 to 4. A is 1. B is an integer of 2 to 25, preferably an integer of 4 to 20. C is an integer of 0 to 10, preferably 0 or 1. The order of the constituent units in the formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of a partially fluorinated oxetane ring-opening polymer surfactant is described in detail in the specification of U.S. Pat. No. 5,650,483.

[0324] A surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer has a function of reducing water penetration and leaching by orienting on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, it is useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure device, and is also useful because it is soluble during development with an alkaline aqueous solution after exposure or post-exposure bake (PEB) and is unlikely to become a foreign matter that causes defects. Such surfactants are insoluble or poorly soluble in water and soluble in an alkaline developer, and are polymer-type surfactants, also called hydrophobic resins, and are particularly preferred for their high water repellency and improved water slippage.

[0325] Specific examples of such polymeric surfactants include those containing at least one repeating unit selected from those represented by any of the following formulas (E1) to (E5). [ka]

[0326] In formulas (E1) to (E5), R B is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 R is -CH2-, -CH2CH2-, -O- or two -H separated from each other. s1are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 R are each independently a hydrogen atom, a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group. s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. s4 is a (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer of 1 to 3. s5 each independently represents a hydrogen atom or -C(=O)-OR sa R is a group represented by the formula: sa R is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 is a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be present between the carbon-carbon bonds.

[0327] R s1 The hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) is preferably a saturated hydrocarbyl group, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, those having 1 to 6 carbon atoms are preferred.

[0328] R s2 The hydrocarbylene group represented by the formula (I) is preferably a saturated hydrocarbylene group, which may be linear, branched or cyclic. Specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group and a pentylene group.

[0329] R s3 or R s6 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups, and aliphatic unsaturated hydrocarbyl groups such as alkenyl groups and alkynyl groups, with saturated hydrocarbyl groups being preferred. As the saturated hydrocarbyl group, R s1 In addition to the examples of the hydrocarbyl group represented by the formula (I), examples thereof include an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group. s3 or R s6 Examples of the fluorinated hydrocarbyl group represented by the formula (1) include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbyl group described above have been substituted with fluorine atoms. As described above, an ether bond or a carbonyl group may be present between these carbon-carbon bonds.

[0330] R s3 Specific examples of the acid labile group represented by the formula (AL-1) to (AL-3) include the groups represented by the formulas (AL-1) to (AL-3) above, trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and oxo group-containing alkyl groups having 4 to 20 carbon atoms.

[0331] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by the formula (1) may be linear, branched, or cyclic, and specific examples thereof include groups obtained by further eliminating u hydrogen atoms from the above-mentioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0332] R saThe fluorinated hydrocarbyl group represented by the formula (I) is preferably saturated and may be linear, branched or cyclic. Specific examples thereof include those in which some or all of the hydrogen atoms of the hydrocarbyl groups have been substituted with fluorine atoms, and specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3,3,3-trifluoro-1-propyl group, a 3,3,3-trifluoro-2-propyl group, a 2,2,3,3-tetrafluoropropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, a 2,2,3,3,4,4,4-heptafluorobutyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, a 2-(perfluorobutyl)ethyl group, a 2-(perfluorohexyl)ethyl group, a 2-(perfluorooctyl)ethyl group, and a 2-(perfluorodecyl)ethyl group.

[0333] Specific examples of the repeating unit represented by any one of formulas (E1) to (E5) include, but are not limited to, those shown below. B is the same as above. [ka]

[0334] [ka]

[0335] [ka]

[0336] [ka]

[0337] [ka]

[0338] [ka]

[0339] The polymer surfactant may further contain other repeating units than the repeating units represented by formulae (E1) to (E5). Examples of the other repeating units include repeating units obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymer surfactant, the content of the repeating units represented by formulae (E1) to (E5) in the total repeating units is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %.

[0340] The Mw of the polymer surfactant is preferably from 1,000 to 500,000, and more preferably from 3,000 to 100,000. The Mw / Mn is preferably from 1.0 to 2.0, and more preferably from 1.0 to 1.6.

[0341] The method for synthesizing the polymeric surfactant includes a method in which a monomer containing an unsaturated bond that gives the repeating units represented by formulae (E1) to (E5) and other repeating units as necessary is heated in an organic solvent with the addition of a radical initiator to polymerize. Examples of the organic solvent used during polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of the polymerization initiator include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as it is, or may be protected or partially protected after polymerization.

[0342] When synthesizing the polymeric surfactant, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In this case, the amount of the chain transfer agent added is preferably 0.01 to 10 mol% based on the total moles of the monomers to be polymerized.

[0343] When the chemically amplified resist composition of the present invention contains a surfactant (E), the content is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the base polymer (A). If the surfactant (E) content is 0.1 part by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, and if it is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is low, and the height of the formed fine pattern is sufficiently maintained. The surfactant (E) may be used alone or in combination of two or more kinds.

[0344] [(F) Other ingredients] The chemically amplified resist composition of the present invention may contain, as other components (F), a compound that decomposes with an acid to generate an acid (acid amplifying compound), an organic acid derivative, a fluorine-substituted alcohol, a compound having Mw of 3,000 or less that changes in solubility in a developer by the action of an acid (dissolution inhibitor), and the like. As the acid amplifying compound, the compounds described in JP-A-2009-269953 or JP-A-2010-215608 can be referred to. When the acid amplifying compound is contained, the content is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, relative to 80 parts by mass of the (A) base polymer. If the content is too high, it is difficult to control acid diffusion, and degradation of resolution and pattern shape may occur. As the organic acid derivative, fluorine-substituted alcohol, and dissolution inhibitor, the compounds described in JP-A-2009-269953 or JP-A-2010-215608 can be referred to.

[0345] [Pattern formation method] The pattern forming method of the present invention includes the steps of forming a resist film on a substrate using the above-mentioned chemically amplified resist composition, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer.

[0346] The substrate may be, for example, a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.).

[0347] The resist film can be formed, for example, by applying the chemically amplified resist composition onto a substrate by a method such as spin coating so that the film thickness is preferably 0.05 to 2 μm, and then pre-baking the composition on a hot plate, preferably at 60 to 150° C. for 1 to 10 minutes, more preferably at 80 to 140° C. for 1 to 5 minutes.

[0348] Examples of high energy rays used for exposing the resist film include KrF excimer laser light, ArF excimer laser light, EB, EUV, etc. When KrF excimer laser light, ArF excimer laser light, or EUV is used for exposure, a mask for forming a desired pattern is used, and the exposure amount is preferably 1 to 200 mJ / cm. 2 , more preferably 10 to 100 mJ / cm 2 When EB is used, the exposure dose is preferably 1 to 300 μC / cm 2 , either directly or through a mask for forming a desired pattern. 2 , more preferably 10 to 200 μC / cm 2 Irradiate so that

[0349] In addition to the usual exposure method, the immersion method can be used in which a liquid with a refractive index of 1.0 or more is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0350] The water-insoluble protective film is used to prevent elution from the resist film and to increase the water sliding property of the film surface, and is roughly divided into two types. One is an organic solvent stripping type that needs to be stripped before alkaline aqueous solution development by an organic solvent that does not dissolve the resist film, and the other is an alkaline aqueous solution soluble type that is soluble in an alkaline developer and removes the protective film together with removing the soluble part of the resist film. The latter is based on a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and soluble in an alkaline developer, and is preferably a material dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixed solvent thereof. The above-mentioned water-insoluble and alkaline developer-soluble surfactant can also be dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixed solvent thereof.

[0351] After the exposure, PEB may be performed, for example, by heating on a hot plate at preferably 60 to 150° C. for 1 to 5 minutes, more preferably 80 to 140° C. for 1 to 3 minutes.

[0352] The development is carried out, for example, using a developer, which is an alkaline aqueous solution of tetramethylammonium hydroxide (TMAH) or the like, preferably at 0.1 to 5 mass %, more preferably 2 to 3 mass %, for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, by a conventional method such as a dip method, a puddle method or a spray method, whereby the exposed areas dissolve and the desired pattern is formed on the substrate.

[0353] After the resist film is formed, a pure water rinse may be performed to extract the acid generator and the like from the film surface or to wash away particles, or a rinse may be performed to remove water remaining on the film after exposure.

[0354] Furthermore, the pattern may be formed by a double patterning method. Examples of the double patterning method include a trench method in which a base of a 1:3 trench pattern is processed by a first exposure and etching, and a 1:3 trench pattern is formed by a second exposure with a shifted position to form a 1:1 pattern, and a line method in which a first base of a 1:3 isolated leave pattern is processed by a first exposure and etching, and a second base with a 1:3 isolated leave pattern formed under the first base is processed by a second exposure with a shifted position to form a 1:1 pattern with half the pitch.

[0355] In the pattern forming method of the present invention, a negative tone development method may be used in which an organic solvent is used as a developer instead of the alkaline aqueous solution to dissolve the unexposed areas.

[0356] The organic solvent development may be carried out using, as a developer, 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, propyl cyclohexanone ... Examples of the organic solvent that can be used 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, ethyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more. EXAMPLES

[0357] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The structures of the compounds were confirmed by measuring the molecular ion peaks using mass spectrometry (LC: Agilent 1100 model, MASS: Agilent LC / MSD model). The value of this molecular ion peak is indicated by "MASS".

[0358] [1] Synthesis of monomer [Example 1-1] Synthesis of Monomer A1 [ka] Acenaphthylene carboxylic acid (19.6g) was suspended in toluene (80g) under a nitrogen atmosphere. Oxalyl chloride (15.2g) was added dropwise. After the addition, the internal temperature was raised to 40°C and aged for 4 hours. After aging, the reaction solution was concentrated to obtain acid chloride (19.7g). Then, 1-methylcyclopentanol (12.0g), 4-dimethylaminopyridine (1.2g), and THF (80g) were added and cooled in an ice bath. After cooling, a solution consisting of triethylamine (13.2g) and THF (20g) was added dropwise while maintaining the internal temperature at 20°C or less. After the addition, the internal temperature was raised to 50°C and aged for 12 hours. After aging, the reaction solution was cooled in an ice bath and the reaction was stopped with saturated sodium bicarbonate water (50g). The target substance was extracted with a solvent consisting of toluene (100 ml) and ethyl acetate (50 ml), subjected to a normal aqueous work-up, and after distilling off the solvent, the product was purified by silica gel chromatography to obtain 21.2 g of Monomer A1 as a colorless oil (yield 76%).

[0359] The results of mass spectrometry of Monomer A1 are shown below. MASS:279.1[M+H] +

[0360] [Examples 1-2 to 1-8] Synthesis of Monomers A2 to A8 Various polymerizable monomers were synthesized by various organic synthesis reactions with the corresponding raw materials. The structures of the polymerizable monomers used in the synthesis of the base polymer are shown below. [ka]

[0361] [2] Synthesis of base polymer Among the monomers used in the synthesis of the base polymer, those other than Monomer A1 to Monomer A8 are as follows. [ka]

[0362] [ka]

[0363] [ka]

[0364] [ka]

[0365] [ka]

[0366] [ka]

[0367] [Example 2-1] Synthesis of polymer P-1 In a nitrogen atmosphere, monomer A1 (8.1 g), monomer a1-1 (9.7 g), monomer b2-1 (6.2 g), monomer c-1 (16.1 g), 1.68 g of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) and 50 g of MEK were placed in a flask to prepare a monomer-polymerization initiator solution. 19 g of MEK was placed in another flask in a nitrogen atmosphere, and the mixture was heated to 80° C. with stirring, and the monomer-polymerization initiator solution was then dropped over 4 hours. After the dropwise addition, the temperature of the polymerization liquid was kept at 80° C. and the mixture was stirred for 2 hours, and then cooled to room temperature. The obtained polymerization liquid was dropped into 1,200 g of vigorously stirred hexane, and the precipitated polymer was filtered off. Furthermore, the obtained polymer was washed twice with 240 g of hexane, and then vacuum dried at 50° C. for 20 hours to obtain a white powdery polymer P-1 (yield 39.2 g, yield 98%). Polymer P-1 had an Mw of 9,300 and an Mw / Mn ratio of 1.79. Note that Mw was a value measured in terms of polystyrene by GPC using DMF as a solvent. [ka]

[0368] [Examples 2-2 to 2-34, Comparative Examples 1-1 to 1-16] Synthesis of Polymers P-2 to P-34 and CP-1 to CP-16 The base polymers shown in Tables 1 and 2 were synthesized in the same manner as in Example 2-1, except that the types and compounding ratios of each monomer were changed.

[0369] [Table 1]

[0370] [Table 2]

[0371] [3] Preparation of chemically amplified resist composition [Examples 3-1 to 3-34, Comparative Examples 2-1 to 2-16] The base polymers of the present invention (P-1 to P-34), comparative base polymers (CP-1 to CP-16), photoacid generators (PAG-X to PAG-Y), and quenchers (SQ-1 to SQ-3, AQ-1) were dissolved in a solvent containing 0.01 mass % of surfactant A (Omnova) in the compositions shown in Tables 3 and 4 below to prepare solutions, which were then filtered through a 0.2 μm Teflon (registered trademark) type filter to prepare chemically amplified resist compositions (R-1 to R-34, CR-1 to CR-16).

[0372] [Table 3]

[0373] [Table 4]

[0374] In Tables 3 and 4, the components are as follows. Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol)

[0375] Photoacid generator: PAG-X, PAG-Y [ka]

[0376] Quencher: SQ-1~SQ-3, AQ-1 [ka]

[0377] Surfactant A: 3-methyl-3-(2,2,2-trifluoroethoxymethyl)oxetane-tetrahydrofuran-2,2-dimethyl-1,3-propanediol copolymer (Omnova) [ka] a:(b+b'):(c+c')=1:4-7:0.01-1 (molar ratio) Mw=1500

[0378] [4] EUV Lithography Evaluation (1) [Examples 4-1 to 4-34, Comparative Examples 3-1 to 3-16] Each chemically amplified resist composition (R-1 to R-34, CR-1 to CR-16) shown in Tables 3 and 4 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. This was 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) with varying 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 5 and 6. Thereafter, paddle development was performed with a 2.38 mass % TMAH aqueous solution for 30 seconds, followed by rinsing with a surfactant-containing rinse material and spin drying to obtain a positive pattern. The obtained LS pattern was observed with a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, exposure tolerance (EL), LWR, depth of focus (DOF) and collapse limit were evaluated according to the following methods. The results are shown in Tables 5 and 6.

[0379] [Sensitivity evaluation] The optimal 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 ) was calculated and used as the sensitivity. The smaller this value, the higher the sensitivity.

[0380] [EL Rating] From the exposure amount formed within the range of ±10% (16.2 to 19.8 nm) of the 18 nm space width in the LS pattern, EL (unit: %) was calculated by 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 give LS pattern with line width of 18 nm and pitch of 36 nm

[0381] [LWR rating] E op The dimensions of the LS pattern obtained by irradiating with 10000 times the light were measured in the longitudinal direction of the lines, 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 of the pattern obtained.

[0382] [DOF evaluation] For the evaluation of the depth of focus, the focus range formed within the range of ±10% (16.2 to 19.8 nm) of the dimension of 18 nm in the LS pattern was obtained. The larger this value, the wider the depth of focus.

[0383] [Line pattern collapse limit evaluation] The line dimension of each exposure dose at the optimum focus of the LS pattern was measured at 10 points in the longitudinal direction. The thinnest line dimension obtained without collapse was defined as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0384] [Table 5]

[0385] [Table 6]

[0386] From the results shown in Tables 5 and 6, it was found that the chemically amplified resist composition containing the photoacid generator of the present invention has good sensitivity and is excellent in EL, LWR and DOF. In addition, it was confirmed that the collapse limit value is small and the composition is resistant to pattern collapse even in fine pattern formation. Therefore, it was shown that the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[0387] [5] EUV Lithography Evaluation (2) [Examples 5-1 to 5-34, Comparative Examples 4-1 to 4-16] Each chemically amplified resist composition (R-1 to R-34, CR-1 to CR-16) shown in Tables 3 and 4 was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) made by Shin-Etsu Chemical Co., Ltd. was formed to a thickness of 20 nm, and the resist film was pre-baked for 60 seconds at 105°C using a hot plate to produce a resist film with a thickness of 50 nm. This was exposed using an EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, a hole pattern mask with a pitch of 46 nm on the wafer and a +20% bias), and PEB was performed for 60 seconds using a hot plate at the temperatures shown in Tables 7 and 8, and development was performed for 30 seconds with a 2.38% by mass TMAH aqueous solution to form a hole pattern with a dimension of 23 nm. Using a Hitachi High-Technologies Corporation CD-SEM (CG6300), the exposure dose when the hole dimension was 23 nm was measured and used as the sensitivity. The dimensions of 50 holes were also measured, and the standard deviation (σ) calculated from the results was tripled (3σ) to use as the dimensional variation (CDU). The results are shown in Tables 7 and 8.

[0388] [Table 7]

[0389] [Table 8]

[0390] The results shown in Tables 7 and 8 confirm that the chemically amplified resist composition of the present invention has good sensitivity and excellent CDU.

[0391] [6] Dry etching resistance evaluation [Examples 6-1 to 6-34, Comparative Examples 5-1 to 5-16] 2 g of each of the base polymers (P-1 to P-34, CP-1 to CP-16) shown in Tables 1 and 2 was dissolved in 10 g of cyclohexanone, and the polymer solution was filtered through a 0.2 μm filter. The polymer solution was spin-coated onto a 152 mm square mask blank whose outermost surface was a Cr film to form a film with a thickness of 300 nm. The film was evaluated under the following conditions. Chlorine gas etching test: The difference in thickness of the polymer film before and after etching was determined using a Plasma Thermo mask dry etching system Gen-4. The etching conditions are as follows. Chamber pressure: 6.0mTorr RF power 700V Cl2 gas flow rate: 185sccm O2 flow rate 55sccm He flow rate 9sccm Time 75sec This evaluation indicates that the film has etching resistance even though the difference in film thickness is small, that is, the amount of reduction is small. The results of dry etching resistance are shown in Tables 9 and 10.

[0392] [Table 9]

[0393] [Table 10]

[0394] From the results shown in Tables 9 and 10, it was confirmed that the polymer of the present invention has excellent dry etching resistance in Cl2 / O2-based gas.

Claims

1. A monomer represented by the following formula (A): 【Chemistry 1】 (In the formula, a1 is 1 or 2, and a2 is an integer of 0 to 4. R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L A is a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. R L1 , R L2 and R L3 are each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom; R L1 , R L2 and R L3 Any two of R may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L1 , R L2 and R L3 At least one of has at least one structure selected from a multiple bond, an alicyclic ring, and an aromatic ring.

2. The monomer according to claim 1, which is represented by the following formula (A1): 【Chemistry 2】 (In the formula, a2, R A , R 1 , L A , X L and R L1 ~R L3 is the same as above.)

3. The monomer according to claim 2, which is represented by the following formula (A2): 【Chemistry 3】 (In the formula, a2, R A , R 1 and R L1 ~R L3 is the same as above.)

4. A polymer comprising repeating units derived from the monomer of claim 1.

5. The polymer according to claim 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (a1) and a repeating unit represented by the following formula (a2): 【Chemistry 4】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-X 11 - or -C(=O)-NH-X 11 -, and the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. R 11 represents a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. A.L. 1 and A.L. 2 are each independently an acid labile group. a3 is an integer from 0 to 4.

6. The polymer according to claim 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (b1) and a repeating unit represented by the following formula (b2): 【Chemistry 5】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-O-C(=O)-). R 22 represents a halogen atom, a hydroxy group, a nitro group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. b1 is an integer from 1 to 4. b2 is an integer from 0 to 4, provided that 1≦b1+b2≦5.

7. The polymer according to claim 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (c1), a repeating unit represented by the following formula (c2), a repeating unit represented by the following formula (c3), and a repeating unit represented by the following formula (c4): 【Chemistry 6】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 is a single bond or a phenylene group. Z 2 is **-C(=O)-O-Z 21 -, **-C(=O)-NH-Z 21 -or**-O-Z 21 - is. 21 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-Z 31 - is. 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. Z 4 each independently represents a single bond, ***-Z 41 -C(=O)-O-, ***-C(=O)-NH-Z 41 -or***-O-Z 41 - is. is. Z 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. Z 5 each independently represents a single bond, ****-Z 51 -C(=O)-O-, ****-C(=O)-NH-Z 51 -or****-O-Z 51 - is. 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. Z 6 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, *-C(=O)-O-Z 61 -, *-C(=O)-N(H)-Z 61 -or*-O-Z 61 - is. 61 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, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * represents a bond to a carbon atom in the main chain. ** represents Z 1 *** represents a bond with Z 3 **** represents a bond with Z. 4 Represents a bond with . R 31 and R 32 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. c1 and c2 each independently represent an integer from 0 to 3.

8. A chemically amplified resist composition comprising a base polymer comprising the polymer according to any one of claims 4 to 7, and an organic solvent.

9. The chemically amplified resist composition according to claim 8, further comprising a quencher.

10. The chemically amplified resist composition according to claim 8, further comprising a photoacid generator.

11. The chemically amplified resist composition according to claim 8, further comprising a surfactant.

12. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to claim 8; exposing the resist film to high-energy radiation; and developing the exposed resist film using a developer.

13. 13. The method for forming a pattern according to claim 12, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam or an extreme ultraviolet ray having a wavelength of 3 to 15 nm.

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