Onium salt, chemically amplified resist composition, and pattern forming process

Abstract

To provide an onium salt which is used for a chemically amplified resist composition having excellent solvent solubility, high sensitivity, high contrast, and excellent lithographic performances such as exposure latitude and linewidth roughness, in photolithography using high-energy radiation, a chemically amplified resist composition comprising the onium salt as a photoacid generator, and a pattern forming process using the chemically amplified resist composition.SOLUTION: An onium salt having the following formula (1) is provided. [R1-R12 independently represent H, halogen, or a C1-C20 hydrocarbyl group optionally including a heteroatom; one of R13 and R14 represents a substituent having a terminal sulfonic acid anion; the other represents H, halogen, or a C1-C20 hydrocarbyl group optionally including a heteroatom; and Z+ represents an onium cation.]SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an onium salt, a chemically amplified resist composition, and a method of forming a pattern. [Background technology]

[0002] In recent years, as the integration and speed of LSIs increases, there is a demand for finer pattern rules, and far-ultraviolet lithography and extreme ultraviolet (EUV) lithography are seen as promising next-generation microfabrication technologies. Among these, photolithography using ArF excimer laser light is an essential technology for ultra-fine processing of 0.13 μm or less.

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

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

[0005] In recent years, negative tone resists developed with organic solvents have also been in the limelight, along with positive tone resists developed with alkaline aqueous solutions. In order to resolve very fine hole patterns that cannot be achieved with positive tones by negative tone exposure, a positive resist composition with high resolution is used and developed with an organic solvent to form a negative pattern. Furthermore, studies are being conducted to obtain twice the resolution by combining two developments, an alkaline aqueous solution development and an organic solvent development. As an ArF resist composition for negative tone development with an organic solvent, a conventional positive ArF resist composition can be used, and a pattern formation method using this is described in Patent Documents 1 to 3.

[0006] In order to adapt to the rapid miniaturization of recent years, the development of resist compositions is progressing day by day along with process technology. Various studies have been conducted on photoacid generators, and sulfonium salts consisting of triphenylsulfonium cations and perfluoroalkanesulfonic acid anions are commonly used. However, the acid generated, perfluoroalkanesulfonic acid, especially perfluorooctanesulfonic acid (PFOS), is difficult to decompose, bioaccumulative, and toxic, making it difficult to apply to resist compositions, and currently photoacid generators that generate perfluorobutanesulfonic acid are used. However, when this is used in resist compositions, the generated acid diffuses widely, making it difficult to achieve high resolution. In response to this problem, various partially fluorinated alkanesulfonic acids and their salts have been developed, and for example, Patent Document 1 describes, as prior art, photoacid generators that generate α,α-difluoroalkanesulfonic acid upon exposure, specifically di(4-tert-butylphenyl)iodonium 1,1-difluoro-2-(1-naphthyl)ethanesulfonate and photoacid generators that generate α,α,β,β-tetrafluoroalkanesulfonic acid. However, although the fluorine substitution rate of these products is reduced, they do not have a decomposable substituent such as an ester structure, and therefore are insufficient from the viewpoint of environmental safety due to their easy decomposition. Furthermore, there are limitations to the molecular design for changing the size of the alkanesulfonic acid, and there are also problems such as the high cost of starting materials containing fluorine atoms.

[0007] In addition, with the shrinking of circuit line width, the effect of contrast degradation due to acid diffusion has become more serious in resist compositions. This is because the pattern dimension approaches the diffusion length of the acid, and the mask fidelity and pattern rectangularity are deteriorated due to the increase in the dimensional deviation on the wafer (mask error factor (MEF)) relative to the value of the dimensional deviation on the mask. Therefore, in order to fully obtain the benefits of the shorter wavelength and higher NA of the light source, it is necessary to increase the dissolution contrast or suppress acid diffusion more than with conventional materials. As one of the measures to improve this, lowering the bake temperature reduces acid diffusion, which results in an improvement in the MEF, but this inevitably leads to a lower sensitivity.

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

[0009] Introducing a polar group into the anion of a photoacid generator is effective in suppressing acid diffusion, but is disadvantageous in terms of solvent solubility. In Patent Documents 8 and 9, attempts have been made to ensure solvent solubility by introducing an alicyclic group into the cation portion of the photoacid generator in order to improve solvent solubility, specifically, a cyclohexane ring or an adamantane ring has been introduced. Although the introduction of such an alicyclic group improves solubility, a certain number of carbon atoms is required to ensure solubility, and as a result, the molecular structure of the photoacid generator becomes bulky, which deteriorates lithography performance such as line width roughness (LWR) and dimensional uniformity (CDU) when forming a fine pattern.

[0010] In addition, Patent Document 10 describes a photoacid generator that generates a fluoroalkanesulfonic acid having an anion with an aromatic condensed ring derived from anthracene. Although it has been confirmed that this improves lithography performance to a certain extent, when the number of fluorine atoms bonded to the alkane sulfonic acid structure is 2 to 4, the solubility in organic solvents is not high enough, and there is a concern about precipitation in the solvent. In order to meet the demand for further miniaturization, the development of a new photoacid generator is important, and there is a demand for the development of a photoacid generator that has sufficient control over acid diffusion, excellent solvent solubility, and improves lithography performance. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2008-281974 A [Patent Document 2] JP 2008-281975 A [Patent Document 3] Patent No. 4554665 [Patent Document 4] JP 2007-145797 A [Patent Document 5] Patent No. 5061484 [Patent Document 6] JP 2016-147879 A [Patent Document 7] JP 2015-63472 A [Patent Document 8] Patent No. 5573098 [Patent Document 9] Patent No. 6461919 [Patent Document 10] Patent No. 7109178 [Non-patent literature]

[0012] [Non-Patent Document 1] Journal of Photopolymer Science and Technology, Vol. 17, No. 4, p. 587-601 (2004) Summary of the Invention [Problem to be solved by the invention]

[0013] In response to recent demands for higher resolution resist patterns, resist compositions that use conventional onium salt-type photoacid generators are unable to sufficiently suppress acid diffusion, and as a result, lithography performance such as contrast, MEF, and LWR can be deteriorated.

[0014] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an onium salt used in a chemically amplified resist composition that has excellent solvent solubility, high sensitivity, high contrast, and excellent lithographic performance such as exposure tolerance (EL) and LWR, particularly in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV; a chemically amplified resist composition that contains the onium salt as a photoacid generator; and a pattern formation method that uses the chemically amplified resist composition. [Means for solving the problem]

[0015] As a result of intensive research into achieving the above-mentioned object, the present inventors have found that an onium salt having, as an anion, an alkanesulfonic acid structure having a substituted fused ring structure and five or more fluorine atoms including a trifluoromethyl group has excellent solvent solubility, and that a chemically amplified resist composition using this as a photoacid generator has high sensitivity and high contrast, and is excellent in lithography performance such as EL and LWR, and is extremely effective in forming fine patterns, which has led to the completion of the present invention.

[0016] That is, the present invention provides the following onium salt, chemically amplified resist composition, and pattern forming method. 1. An onium salt represented by the following formula (1): [ka] [In the formula, R 1 ~R 12 are each independently a hydrogen atom, a halogen atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R 13 and R 14 One of these is a group having a partial structure represented by the following formula (1a), and the other is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom, a halogen atom, or a heteroatom. Also, R 1 ~R 14At least two of may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom to which they are bonded and a carbon atom therebetween. Z + is an onium cation. [ka] (In the formula, L A and L B are each independently a single bond, an ether bond, an ester 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. Q 1 ~Q 3 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, provided that Q 1 and Q 2 When both are hydrogen atoms, Q 3 is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 ~Q 3 The total number of fluorine atoms in is 2 or more.)] 2. An onium salt of formula 1, which is represented by the following formula (1A): [ka] (In the formula, R 1 ~R 13 , L A , X L , Q 1 ~Q 3 , and Z + is the same as above.) 3. An onium salt of 2 represented by the following formula (1B): [ka] (In the formula, R 5 , R 10 ~R 13 , L A , X L , Q1 ~Q 3 and Z + is the same as above. n1 and n2 each independently represent an integer of 0 to 4. R 15 and R 16 are each independently a hydrogen atom, a halogen atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 15 and R 16 may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom to which they are bonded and the carbon atom therebetween.) 4. An onium salt of formula 3, which is represented by the following formula (1C): [ka] (In the formula, R 5 , R 10 ~R 13 , R 15 , R 16 , L A , X L and Z + is the same as above.) 5.Z + is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka] (In the formula, 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. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 6. A photoacid generator comprising any one of the onium salts of 1 to 5. 7. A chemically amplified resist composition comprising a photoacid generator according to claim 6. 8. The chemically amplified resist composition of 7, comprising a base polymer containing a repeating unit represented by the following formula (a1): [ka] (In the formula, R A is 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, or *-C(=O)-OX 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 represents 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. * represents a bond to a carbon atom of the main chain. AL 1 is an acid labile group. 9. The chemically amplified resist composition of 8, wherein the base polymer contains a repeating unit represented by the following formula (a2): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 2 is a single bond or *-C(=O)-O-. * 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. AL 2 is an acid labile group. a is an integer from 0 to 4. 10. The chemically amplified resist composition of 8 or 9, wherein the base polymer contains a repeating unit represented by the following formula (b1) or (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. b is an integer from 1 to 4; c is an integer from 0 to 4, provided that 1≦b+c≦5. 11. The chemically amplified resist composition of any one of 8 to 10, wherein the base polymer contains 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 Aeach 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 are each independently 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.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 3 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 and 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. d is an integer from 0 to 3. 12. Any one of the chemically amplified resist compositions 7 to 11, further comprising an organic solvent. 13. Any one of the chemically amplified resist compositions of 7 to 12, further comprising a quencher. 14. The chemically amplified resist composition according to any one of 7 to 13, further comprising a photoacid generator other than the photoacid generator according to 6. 15. Any one of the chemically amplified resist compositions according to 7 to 14, further comprising a surfactant. 16. 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 7 to 15, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer. 17. The pattern formation method according to claim 16, 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

[0017] When a pattern is formed using a chemically amplified resist composition containing the onium salt of the present invention as a photoacid generator, the composition has high sensitivity, is excellent in acid diffusion suppression ability, and exhibits improved lithography performance such as MEF and LWR, and can suppress collapse of the resist pattern during fine pattern formation. [Brief description of the drawings]

[0018] [Figure 1] 1 is a nuclear magnetic resonance spectrum (1H-NMR / DMSO-d6) of the onium salt PAG-1 synthesized in Example 1-1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [Onium salts] The onium salt of the present invention is represented by the following formula (1). [ka]

[0020] In formula (1), R 1 ~R 12 R are each independently a hydrogen atom, a halogen atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 13 and R14 One of these is a group having a partial structure represented by formula (1a) described below, and the other is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom, a halogen atom, or a heteroatom.

[0021] 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-methyl group, and the like. Examples of such groups include cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a 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.

[0022] Also, R 1 ~R 14 At least two of the above may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom to which they are bonded and the carbon atom therebetween. Specific examples of the ring formed in this case include alicyclic rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, and an adamantane ring, and aromatic rings such as a benzene ring, a naphthalene ring, and an anthracene 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 the -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 hydroxyl 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. Specific examples thereof include R 1 Examples of the hydrocarbyl group include the same as those exemplified above for the hydrocarbyl group represented by the following formula: The ring is preferably an aromatic ring, and more preferably a benzene ring.

[0023] In formula (1), R 13 or R 14 is a group having a partial structure represented by the following formula (1a). 14 is preferably a group having a partial structure represented by the following formula (1a). [ka]

[0024] In formula (1a), L A and L B are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, a single bond, an ether bond or an ester bond is preferred.

[0025] In formula (1a), 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, etc. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, etc.

[0026] 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, * represents L A and L B Represents a bond with . [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] Of these, X L -0~X L -22 and X L -47~X L -58 is preferred.

[0031] In formula (1a), Q 1 ~Q 3 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. As the fluorinated saturated hydrocarbyl group, a trifluoromethyl group is preferable.

[0032] In formula (1a), Q 1 and Q 2 When both are hydrogen atoms, Q 3 is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. The fluorinated saturated hydrocarbyl group is preferably a trifluoromethyl group.

[0033] In formula (1a), Q 1 ~Q 3 The total number of fluorine atoms in the onium salt must be at least 2. This improves the solubility of the onium salt in a solvent, allowing it to dissolve uniformly in a resist solvent, improving various lithography performances.

[0034] In formula (1a), -C(CF3)(Q 3 )-C(Q 1 )(Q 2 )-SO3 - Specific examples of the partial structure represented by the formula (I) are preferably, but are not limited to, those shown below. In the formula (I), * represents L B Represents a bond with . [ka]

[0035] Among these, Acid-1 and Acid-3 are preferred from the viewpoint of synthesis. In Acid-1, the carbon atom to which the trifluoromethyl group is bonded becomes an asymmetric carbon, so that diastereomers are generated in the anion structure, and the solvent solubility is improved. Although Acid-2 does not generate diastereomers like Acid-1, the number of fluorine atoms is increased, and thus the solvent solubility is improved.

[0036] The onium salt represented by formula (1) is preferably one represented by the following formula (1A). [ka] (In the formula, R 1 ~R 13 , L A , XL , Q 1 ~Q 3 and Z + is the same as above.)

[0037] The onium salt represented by formula (1A) is preferably one represented by the following formula (1B). [ka] (In the formula, R 5 , R 10 ~R 13 , L A , X L , Q 1 ~Q 3 and Z + is the same as above.)

[0038] In formula (1B), R 15 and R 16 are each independently a hydrogen atom, a halogen atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. Specific examples of the halogen atom and hydrocarbyl group include R 1 ~R 14 Examples of the halogen atom and hydrocarbyl group represented by the following formula include the same as those exemplified above.

[0039] In formula (1B), n1 and n2 each independently represent an integer of 0 to 4. Of these, from the viewpoint of raw material procurement, it is preferable that both are 0 to 2.

[0040] In formula (1B), when n1 and n2 are 2 or more, a plurality of R 15 and R 16 may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom to which they are bonded and the carbon atom between them. Specific examples of the ring formed in this case include R 1 ~R 14 Examples of the ring that can be formed by bonding at least two of the above groups to each other include the same as those exemplified above.

[0041] The onium salt represented by formula (1B) is preferably one represented by the following formula (1C). [ka] (In the formula, R 5 , R 10 ~R 13 , R 15 , R 16 , L A , X L and Z + is the same as above.)

[0042] Specific examples of the anion of the onium salt represented by formula (1) include, but are not limited to, those shown below: In the following formula, Me is a methyl group. [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[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] In formula (1), Z +is an onium cation. 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]

[0060] 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.

[0061] 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.

[0062] 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, an allyl group, a 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.

[0063] 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 combination with .)

[0064] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074]

change

[0075]

change

[0076]

change

[0077]

change

[0078]

change

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085] [ka]

[0086] [ka]

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0092] [ka]

[0093] Specific examples of the onium salt of the present invention include any combination of the above-mentioned anions and cations.

[0094] The onium salt of the present invention can be synthesized by a known method. As an example, a method for producing an onium salt represented by the following formula (PAG-1-ex) will be described, but the synthesis method is not limited thereto. [ka] (In the formula, R 1 ~R 13 , L A , X L , Q 1 ~Q 3 and Z + is the same as above. + is the counter cation. X - is the counter anion.)

[0095] The first step is a step of obtaining intermediate In-1 by reacting raw material SM-1 obtained by a commercially available product or a known synthesis method with raw material SM-2. When directly forming an ester bond from the carboxy group of raw material SM-1 and the hydroxy group of raw material SM-2, various condensation agents can be used. Examples of the condensation agent to be used include N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. From the viewpoint of ease of removal of the urea compound generated as a by-product after the reaction, it is preferable to use 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The reaction is carried out by dissolving raw materials SM-1 and SM-2 in a halogen-based solvent such as methylene chloride and adding a condensation agent. The reaction rate can be improved by adding 4-dimethylaminopyridine (DMAP) as a catalyst. The reaction time is usually about 12 to 24 hours, although it is desirable to follow the reaction by silica gel thin layer chromatography (TLC) to complete the reaction in terms of yield. After the reaction is stopped, the by-produced urea compound is removed by filtration or washing with water as necessary, and the reaction solution is subjected to a conventional aqueous work-up to obtain intermediate In-1. The obtained intermediate In-1 may be purified by conventional methods such as chromatography and recrystallization, if necessary.

[0096] In the second step, the obtained intermediate In-1 is converted to Z + X - This is a process for obtaining an onium salt (PAG-1-ex) by salt exchange with an onium salt (raw material SM-3) represented by the formula: - As the anion, chloride ion, bromide ion, iodide ion, or methyl sulfate anion is preferable because the exchange reaction easily proceeds quantitatively. It is preferable to confirm the progress of the reaction by TLC in terms of yield. The onium salt (PAG-1-ex) can be obtained from the reaction mixture by a normal aqueous work-up. If necessary, it can be purified by a normal method such as chromatography or recrystallization.

[0097] In the above scheme, the ion exchange in the second step can be easily carried out by a known method, for example, see JP-A-2007-145797.

[0098] The above-mentioned production method is merely one example, and the production method of the onium salt of the present invention is not limited thereto.

[0099] The structural features of the onium salt of the present invention include that a fused ring structure having a substituent and an alkane sulfonic acid structure having 5 or more fluorine atoms including a trifluoromethyl group are introduced into the anion. The fused ring structure having a substituent has a large excluded volume and acts as a bulky substituent, highly suppressing the diffusion of the generated acid. In addition, since it is resistant to an alkaline developer, it reduces the film loss of the pattern in the unexposed area. On the other hand, an alkane sulfonic acid structure having 5 or more fluorine atoms including a trifluoromethyl group increases the acidity of the generated acid to deprotect the acid labile group of the base polymer, and the carbon atom to which the trifluoromethyl group is bonded becomes an asymmetric carbon, thereby generating an isomer in the anion. The generation of the isomer reduces the crystallization ability of the target product, and the increase in the number of fluorine atoms improves the solvent solubility. In addition, since fluorine atoms are an element that has a high absorption effect of EUV light, although not as much as iodine atoms, the increase in the number of fluorine atoms increases the amount of secondary electrons generated, promoting the decomposition of cations and contributing to high sensitivity. In Japanese Patent No. 7109178, an alkanesulfonic acid type photoacid generator having 2 to 4 fluorine atoms is proposed, but since these do not produce isomers and have poor solvent solubility, there is a concern of development defects, and since the number of fluorine atoms is smaller than that of the photoacid generator of the present invention, it is expected that the contribution to high sensitivity is small. Due to these synergistic effects, the resist composition containing the onium salt of the present invention has high sensitivity and low acid diffusibility, and therefore is excellent in LWR of line patterns and CDU of hole patterns, and enables the formation of patterns that are resistant to pattern collapse, making it suitable for forming fine patterns.

[0100] The onium salt can be suitably used as a photoacid generator.

[0101] [Chemically amplified resist composition] [(A) Photoacid generator] The chemically amplified resist composition of the present invention contains, as an essential component, (A) a photoacid generator comprising an onium salt represented by formula (1).

[0102] In the chemically amplified resist composition of the present invention, the content of the photoacid generator consisting of an onium salt represented by formula (1) as component (A) is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 30 parts by mass, relative to 80 parts by mass of the base polymer described below. If the content of component (A) is within the above range, the sensitivity and resolution are 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 as component (A) may be used alone or in combination of two or more types.

[0103] [(B) Base polymer] The chemically amplified resist composition of the present invention may contain a base polymer as component (B). The base polymer (B) contains a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1): [ka]

[0104] In formula (a1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0105] In formula (a1), X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 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 represents 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. * represents a bond to a carbon atom of the main chain.

[0106] In formula (a1), AL 1 is an acid labile group. Examples of the acid labile group include those described in JP-A-2013-80033 and JP-A-2013-83821.

[0107] 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.)

[0108] In formulas (AL-1) and (AL-2), R L1 and R L2 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.

[0109] In formula (AL-1), k is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0110] In formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain 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. In addition, R L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0111] In formula (AL-3), R L5 , R L6 and R L7are each independently 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. The hydrocarbyl group preferably has 1 to 20 carbon atoms. In addition, R L5 , R L6 and R L7 Any two of these may be bonded to each other to form, together with the carbon 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.

[0112] 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]

[0113] [ka]

[0114] [ka]

[0115] The base polymer may further include a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0116] In formula (a2), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 11is 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 2 is an acid labile group. The acid labile group is, for example, AL 1 Examples of the acid labile group represented by the formula: are the same as those given above. a is an integer of 0 to 4, and preferably 0 or 1.

[0117] 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]

[0118] [ka]

[0119] The base 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]

[0120] 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 21R 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)-). 22 is 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. b is an integer of 1 to 4. c is an integer of 0 to 4, with the proviso that 1≦b+c≦5.

[0121] Specific examples of the repeating unit b1 include, but are not limited to, those shown below. A is the same as above. [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126]

change

[0127]

change

[0128]

change

[0129]

change

[0130]

change

[0131]

change

[0132]

change

[0133]

change

[0134]

change

[0135]

change

[0136]

change

[0137] Specific examples of the repeating unit b2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] [ka]

[0142] 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.

[0143] The base polymer may further contain at least one 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). [ka]

[0144] In formulas (c1) to (c4), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is 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 are each independently 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.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 hydroxyl group. * represents a bond to a carbon atom in the main chain. ** represents Z 3 Represents a bond with .

[0145] 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.

[0146] 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.)

[0147] 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, allyl, 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.

[0148] Also, R 31 and R 32 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is as defined in the description of formula (cation-1) as R ct1 and R ct2 Examples of the ring that can be formed by bonding with the sulfur atom to which they are bonded include the same as those exemplified above.

[0149] 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]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] [ka]

[0155] [ka]

[0156] 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 imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, and bis(perfluorobutylsulfonyl)imide ion; tris(trifluoromethylsulfonyl)methide ion, and tris(perfluoroethylsulfonyl)methide ion.

[0157] Other examples of the non-nucleophilic counter ion include anions represented by any of the following formulas (c1-1) to (c1-4). [ka]

[0158] 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 fa1Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0159] The anion represented by formula (c1-1) is preferably one represented by the following formula (c1-1-1): [ka]

[0160] In formula (c1-1-1), Q 11 and Q 12 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, etc., 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.

[0161] In formula (c1-1-1), R fa1The hydrocarbyl group having 1 to 35 carbon atoms and 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 a cyclohexyl group. Examples of the alkyl group include cyclic saturated hydrocarbyl groups having 3 to 35 carbon atoms, such as bornylmethyl group, tricyclodecyl group, tetracyclododecyl group, tetracyclododecylmethyl group, and dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 35 carbon atoms, such as allyl group and 3-cyclohexenyl group; aryl groups having 6 to 35 carbon atoms, such as phenyl group, 1-naphthyl group, 2-naphthyl group, and 9-fluorenyl group; aralkyl groups having 7 to 35 carbon atoms, such as benzyl group and diphenylmethyl group; and groups obtained by combining these groups.

[0162] 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.

[0163] 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.

[0164] Specific examples of the anion represented by formula (c1-1) include, but are not limited to, those shown below. In the following formula, Q 11 is the same as above, and Ac is an acetyl group. [ka]

[0165] [ka]

[0166] [ka]

[0167] [ka]

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] 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.

[0175] 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 R fc3is 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.

[0176] 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.

[0177] Specific examples of the anion represented by formula (c1-4) include, but are not limited to, those shown below. [ka]

[0178] [ka]

[0179] 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]

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] Specific 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]

[0188] [ka]

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] [ka]

[0196] [ka]

[0197]

change

[0198]

change

[0199]

change

[0200]

change

[0201]

change

[0202]

change

[0203]

change

[0204]

change

[0205]

change

[0206]

change

[0207] [ka]

[0208] [ka]

[0209] [ka]

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] In formulae (c2) and (c3), d is an integer of 0 to 3, with 1 being preferred.

[0217] 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]

[0218] [ka]

[0219] [ka]

[0220] [ka]

[0221] [ka]

[0222] [ka]

[0223] [ka]

[0224] [ka]

[0225] [ka]

[0226] 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]

[0227] [ka]

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] [ka]

[0232] [ka]

[0233] [ka]

[0234] 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]

[0235] In formulas (c2) to (c4), A +is an onium cation. The onium cation may be an ammonium cation, a sulfonium cation, or an iodonium cation, but is preferably a sulfonium cation or an iodonium cation. Specific examples thereof include those exemplified as the sulfonium cation represented by formula (cation-1) and the iodonium cation represented by formula (cation-2), and those exemplified as the ammonium cation represented by formula (cation-3) described below, but are not limited thereto.

[0236] Specific structures of the repeating units c1 to c4 include any combination of the above-mentioned anions and cations.

[0237] 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.

[0238] 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]

[0239] 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.

[0240] In formula (d1), R 42The 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 hydroxyl 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.

[0241] R 42 Specific examples of the acid labile group represented by the formula (d2), the alkoxymethyl group represented by the formula (d3), and the repeating unit d are the same as those exemplified in the description of the repeating unit d described in JP-A-2020-111564.

[0242] The base polymer may further include a repeating unit e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or a derivative thereof. Specific examples of monomers that provide the repeating unit e include, but are not limited to, the following: [ka]

[0243] The base polymer may further include a repeat unit f derived from indane, vinylpyridine, or vinylcarbazole.

[0244] In the polymer of the present invention, the content ratios of the repeating units a1, a2, b1, b2, c1 to c4, d, e, and f are preferably 0 < a1 ≤ 0.8, 0 ≤ a2 ≤ 0.8, 0 ≤ b1 ≤ 0.6, 0 ≤ b2 ≤ 0.6, 0 ≤ c1 ≤ 0.4, 0 ≤ c2 ≤ 0.4, 0 ≤ c3 ≤ 0.4, 0 ≤ c4 ≤ 0.4, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.3, and 0 ≤ f ≤ 0.3, and more preferably 0 < a1 ≤ 0.7, 0 ≤ a2 ≤ 0.7, 0 ≤ b1 ≤ 0.5, 0 ≤ b2 ≤ 0.5, 0 ≤ c1 ≤ 0.3, 0 ≤ c2 ≤ 0.3, 0 ≤ c3 ≤ 0.3, 0 ≤ c4 ≤ 0.3, 0 ≤ d ≤ 0.3, 0 ≤ e ≤ 0.3, and 0 ≤ f ≤ 0.3.

[0245] The weight average molecular weight (Mw) of the polymer is preferably from 1000 to 500000, more preferably from 3000 to 100000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of a decrease in resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene-equivalent measurement value by gel permeation chromatography (GPC) using THF or N,N-dimethylformamide (DMF) as a solvent.

[0246] Furthermore, since the influence of Mw / Mn becomes larger as the pattern rule becomes finer, in order to obtain a resist composition suitably used for fine pattern dimensions, Mw / Mn is preferably narrowly dispersed in the range of 1.0 to 2.0. If it is within the above range, there is little risk of low molecular weight or high molecular weight polymers, and there is no risk of foreign matter being seen on the pattern or the pattern shape deteriorating after exposure.

[0247] To synthesize the polymer, for example, monomers that give the above-described repeating units may be heated in an organic solvent with the addition of a radical polymerization initiator to carry out polymerization.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] 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.

[0252] 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.

[0253] 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.

[0254] 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.

[0255] 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.

[0256] 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.

[0257] 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.

[0258] 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.

[0259] The base polymer (B) may be used alone or in combination with two or more different polymers having different composition ratios, Mw and / or Mw / Mn. The base polymer (B) may contain, in addition to the above-mentioned polymer, a hydrogenated ring-opening metathesis polymer, and the polymers described in JP-A-2003-66612 can be used.

[0260] [(C) Organic solvent] The chemically amplified resist composition of the present invention may contain an organic solvent as component (C). The organic solvent (C) is not particularly limited 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.

[0261] 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 (B).

[0262] In the chemically amplified resist composition of the present invention, the content of the organic solvent (C) 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 (B). The organic solvent (C) may be used alone or in combination of two or more kinds.

[0263] [(D) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (D). 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.

[0264] The (D) quencher includes an onium salt represented by the following formula (2) or (3). [ka]

[0265] In formula (2), R q1 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, except for 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.

[0266] 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. In addition, some or all of the hydrogen atoms of 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- of 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.

[0267] 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.

[0268] Specific examples of the anion of the onium salt represented by formula (2) include, but are not limited to, those shown below. [ka]

[0269] [ka]

[0270] [ka]

[0271] [ka]

[0272] Specific examples of the anion of the onium salt represented by formula (3) include, but are not limited to, those shown below. [ka]

[0273] [ka]

[0274] [ka]

[0275] In formulas (2) and (3), 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]

[0276] 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.

[0277] Specific examples of the ammonium cation represented by formula (cation-3) include, but are not limited to, those shown below. [ka]

[0278] Specific examples of the onium salt represented by formula (2) or (3) 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.

[0279] The onium salt represented by formula (2) or (3) 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 weak acid here means an acidity that cannot deprotect the acid labile group of the acid labile group-containing unit used in the base polymer. The onium salt represented by formula (2) or (3) 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 weaker acid with a lower catalytic activity, and the acid appears to be deactivated, thereby enabling control of acid diffusion.

[0280] In addition, as the (D) quencher, an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent 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.

[0281] 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.

[0282] When the chemically amplified resist composition of the present invention contains an onium salt represented by formula (2) or (3) as a quencher (D), 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 (B). If the onium salt type quencher of the component (D) 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 (2) or (3) can be used alone or in combination of two or more kinds.

[0283] The chemically amplified resist composition of the present invention may contain a nitrogen-containing compound as a quencher (D). The nitrogen-containing compound of component (D) 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.

[0284] 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.

[0285] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as a quencher (D), 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 (B). The nitrogen-containing compound may be used alone or in combination of two or more kinds.

[0286] [(E) Other photoacid generators] The chemically amplified resist composition of the present invention may contain a photoacid generator other than the component (A) (hereinafter, also referred to as other photoacid generator) as the component (E). The other photoacid generator is not particularly limited as long as it is a compound that generates an acid upon exposure to high-energy radiation. Suitable other photoacid generators include those represented by the following formula (4) or (5). [ka]

[0287] In formula (4), 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 ct5Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0288] Specific examples of the cation of the sulfonium salt represented by formula (4) 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 (5) include the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0289] In formulas (4) and (5), 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).

[0290] As another photoacid generator of the component (E), a compound represented by the following formula (6) is also preferred. [ka]

[0291] In formula (6), 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.

[0292] 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.

[0293] 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.

[0294] In formula (6), L Ais 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 following formula include the same as those exemplified above.

[0295] In formula (6), 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.

[0296] The photoacid generator represented by formula (6) is preferably one represented by the following formula (6'). [ka]

[0297] In formula (6'), L A 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.

[0298] Examples of the photoacid generator represented by formula (6) include the same as those exemplified as the photoacid generator represented by formula (2) in JP2017-26980A.

[0299] Among the other 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 (6') are particularly preferred because of their extremely small acid diffusion.

[0300] When the chemically amplified resist composition of the present invention contains the other photoacid generator (E), 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 (B). If the amount of the photoacid generator (E) 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 other photoacid generators (E) may be used alone or in combination of two or more.

[0301] [(F) Surfactant] The chemically amplified resist composition of the present invention may further contain a surfactant as component (F). The surfactant (F) 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 JP2010-215608A and JP2011-16746A.

[0302] 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]

[0303] 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.)

[0304] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferable.

[0305] 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.

[0306] 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.

[0307] Specific examples of such polymeric surfactants include those containing at least one repeating unit selected from those represented by any of the following formulas (7A) to (7E). [ka]

[0308] In formulas (7A) to (7E), 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. s1 are 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)-ORsa 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.

[0309] 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.

[0310] 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.

[0311] 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 of the hydrocarbyl group represented by the formula (I) include an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group. s3 or R s6The fluorinated hydrocarbyl group represented by the formula (I) includes a group 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.

[0312] R s3 Specific examples of the acid labile group represented by the formula (AL-3) to (AL-5) include the groups represented by the formulas (AL-3) to (AL-5) 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.

[0313] 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.

[0314] R sa The 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.

[0315] Specific examples of the repeating unit represented by any one of formulas (7A) to (7E) include, but are not limited to, those shown below. B is the same as above. [ka]

[0316] [ka]

[0317] [ka]

[0318] [ka]

[0319] [ka]

[0320] [ka]

[0321] The polymer surfactant may further contain other repeating units than the repeating units represented by formulae (7A) to (7E). 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 (7A) to (7E) in the total repeating units is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %.

[0322] 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.

[0323] 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 (7A) to (7E) 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.

[0324] 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.

[0325] When the chemically amplified resist composition of the present invention contains a surfactant (F), the content thereof 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 (B). If the content of the surfactant (F) 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 (F) may be used alone or in combination of two or more kinds.

[0326] [(G) Other ingredients] The chemically amplified resist composition of the present invention may contain, as other components (G), 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 (B) 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.

[0327] [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.

[0328] 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.).

[0329] 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.

[0330] 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

[0331] 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.

[0332] 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.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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.

[0337] 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.

[0338] 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

[0339] 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 apparatuses used are as follows. IR: Thermo Fisher Scientific NICOLET 6700 · 1 H-NMR: ECA-500 manufactured by JEOL Ltd. MALDI TOF-MS: JEOL S3000

[0340] [1] Synthesis of onium salts [Example 1-1] Synthesis of onium salt PAG-1 [ka]

[0341] (1) Synthesis of intermediate In-1 In a nitrogen atmosphere, raw materials SM-1 (10.0 g), SM-2 (15.9 g), DMAP (0.5 g) and methylene chloride (100 g) were added to a reaction vessel and cooled in an ice bath. While maintaining the temperature in the reaction vessel at 20°C or less, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (9.2 g) was added as a powder. After the addition, the temperature was raised to room temperature and aged for 12 hours. After aging, water was added to stop the reaction, and a normal aqueous work-up was performed. After the solvent was distilled off, diisopropyl ether was added to wash the residue, and 23.9 g of intermediate In-1 was obtained as an oil (yield 98%).

[0342] (2) Synthesis of PAG-1 Under a nitrogen atmosphere, intermediate In-1 (9.2 g), raw material SM-3 (6.6 g), methylene chloride (50 g), and water (30 g) were added, stirred for 15 minutes, and then the organic layer was separated and washed with water, and then concentrated under reduced pressure. Methyl isobutyl ketone (50 g) was added to the concentrated liquid to carry out azeotropic dehydration, and diisopropyl ether was further added to wash the residue, obtaining 11.3 g of the target product PAG-1 as an oil (yield 97%).

[0343] The IR spectrum data and TOF-MS results of PAG-1 are shown below. The nuclear magnetic resonance spectrum ( 1 The results of H-NMR / DMSO-d6) are shown in Figure 1. IR(D-ATR): ν= 3101, 3061, 2971, 1769, 1708, 1587, 1492, 1468, 1459, 1407, 1371, 1329, 1247, 1186, 1171, 1161, 1130, 1113, 1072, 1009, 992, 930, 912, 887, 874, 838, 763, 736, 703, 642, 607, 577, 553, 519, 438 cm -1 . MALDI TOF-MS: POSITIVE M + 317(C 18 H 12 F3S + equivalent) NEGATIVE M - 461(C 20 H 14 F5O5S - equivalent)

[0344] [Examples 1-2 to 1-9] Synthesis of onium salts PAG-2 to PAG-9 Using the corresponding raw materials and known organic synthesis reactions, onium salts PAG-2 to PAG-10 represented by the following formulas were synthesized. [ka]

[0345] [ka]

[0346] [2] Synthesis of base polymer [Synthesis Example] Synthesis of base polymers (P-1 to P-5) Each monomer was combined and copolymerized in MEK, the solvent, and the reaction solution was poured into hexane. The precipitated solid was washed with hexane, isolated, and dried to obtain base polymers (P-1 to P-5) with the following compositions. The resulting base polymers had the following compositions: 1 Mw and Mw / Mn were confirmed by H-NMR and GPC (solvent: THF, standard: polystyrene). [ka]

[0347] [ka]

[0348] [3] Preparation of chemically amplified resist composition [Examples 2-1 to 2-30, Comparative Examples 1-1 to 1-20] The onium salts of the present invention (PAG-1 to PAG-9), comparative photoacid generators (PAG-A to PAG-E), other photoacid generators (PAG-X, PAG-Y), base polymers (P-1 to P-5) and quenchers (Q-1 to Q-4) were dissolved in a solvent containing 0.01 mass % of surfactant A (Omnova) in the compositions shown in Tables 1 and 2 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-30 and CR-1 to CR-20).

[0349] [Table 1]

[0350] [Table 2]

[0351] In Tables 1 and 2, the solvent, other photoacid generators PAG-X and PAG-Y, comparative photoacid generators PAG-A to PAG-E, quenchers Q-1 to Q-4, and surfactant A are as follows. Solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol)

[0352] Other photoacid generators: PAG-X, PAG-Y [ka]

[0353] Photoacid generators for comparison: PAG-A to PAG-E [ka]

[0354] Quencher: Q-1~Q-4 [ka]

[0355] 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

[0356] [4] EUV Lithography Evaluation (1) [Examples 3-1 to 3-30, Comparative Examples 2-1 to 2-20] Each chemically amplified resist composition (R-1 to R-30, CR-1 to CR-20) shown in Tables 1 to 3 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. was 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. The resist film 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 NXE3400 (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 4 and 5. 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-Tech Corp., and the sensitivity, EL, LWR, depth of focus (DOF) and collapse limit were evaluated according to the following methods. The results are shown in Tables 3 and 4.

[0357] [Sensitivity evaluation] The optimal exposure dose Eop (mJ / cm) to obtain an LS pattern with a line width of 18 nm and a pitch of 36 nm 2) was calculated and used as the sensitivity. The smaller this value, the higher the sensitivity.

[0358] [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| / Eop)×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 Eop: Optimal exposure dose for LS pattern with line width of 18 nm and pitch of 36 nm

[0359] [LWR rating] The LS pattern obtained by irradiating at Eop was measured at 10 points along the line length, and the LWR was calculated as three times the standard deviation (σ). The smaller this value, the smaller the roughness and the more uniform the line width of the pattern.

[0360] [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.

[0361] [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.

[0362] [Table 3]

[0363] [Table 4]

[0364] From the results shown in Tables 3 and 4, it was found that the chemically amplified resist composition containing the photoacid generator made of an onium salt of the present invention has good sensitivity and is excellent in EL, LWR and DOF. It was also confirmed that the collapse limit value was small and the composition was 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.

[0365] [5] EUV Lithography Evaluation (2) [Examples 4-1 to 4-30, Comparative Examples 3-1 to 3-20] Each chemically amplified resist composition (R-1 to R-30, CR-1 to CR-20) shown in Tables 1 to 3 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 substrate was pre-baked at 105°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. The resist film 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) made by ASML, and PEB was performed for 60 seconds at the temperatures shown in Tables 7 and 8 using a hot plate, 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 5 and 6.

[0366] [Table 5]

[0367] [Table 6]

[0368] The results shown in Tables 5 and 6 demonstrate that the chemically amplified resist composition containing a photoacid generator made of an onium salt of the present invention has good sensitivity and excellent CDU.

Claims

1. An onium salt represented by the following formula (1): 【Chemistry 1】 [In the formula, R 1 ~R 12 are each independently a hydrogen atom, a halogen atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R 13 and R 14 One of these is a group having a partial structure represented by the following formula (1a), and the other is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom, a halogen atom, or a heteroatom. Also, R 1 ~R 14 At least two of may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom to which they are bonded and a carbon atom therebetween. Z + is an onium cation. 【Chemistry 2】 (In the formula, L A and L B are each independently a single bond, an ether bond, an ester 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. Q 1 ~Q 3 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 and Q. 2 When both are hydrogen atoms, Q 3 is a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 ~Q 3 The total number of fluorine atoms in is 2 or more.

2. The onium salt according to claim 1, which is represented by the following formula (1A): 【Chemistry 3】 (In the formula, R 1 ~R 13 , L A , X L , Q 1 ~Q 3 , and Z + is the same as above.)

3. The onium salt according to claim 2, which is represented by the following formula (1B): 【Chemistry 4】 (In the formula, R 5 , R 10 ~R 13 , L A , X L , Q 1 ~Q 3 and Z + is the same as above. n1 and n2 each independently represent an integer of 0 to 4. R 15 and R 16 are each independently a hydrogen atom, a halogen atom, or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 15 and R 16 may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom to which they are bonded and the carbon atom therebetween.)

4. The onium salt according to claim 3, which is represented by the following formula (1C): 【Chemistry 5】 (In the formula, R 5 , R 10 ~R 13 , R 15 , R 16 , L A , X L and Z + is the same as above.)

5. Z + The onium salt according to claim 1, wherein is a sulfonium cation represented by the following formula (category-1) or an iodonium cation represented by the following formula (category-2). 【Chemistry 6】 (In the formula, 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. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

6. A photoacid generator comprising the onium salt according to any one of claims 1 to 5.

7. A chemically amplified resist composition comprising the photoacid generator according to claim 6.

8. 8. The chemically amplified resist composition according to claim 7, comprising a base polymer containing a repeating unit represented by the following formula (a1): 【Chemistry 7】 (In the formula, R A is 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, or *-C(=O)-O-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. * represents a bond to a carbon atom of the main chain. A.L. 1 is an acid labile group.

9. 9. The chemically amplified resist composition according to claim 8, wherein the base polymer comprises a repeating unit represented by the following formula (a2): 【Chemistry 8】 (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 2 is a single bond or *-C(=O)-O-. * 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. A.L. 2 is an acid labile group. a is an integer from 0 to 4.

10. 9. The chemically amplified resist composition according to claim 8, wherein the base polymer contains a repeating unit represented by the following formula (b1) or (b2): 【Chemistry 9】 (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. b is an integer from 1 to 4. c is an integer from 0 to 4, provided that 1≦b+c≦5.

11. The chemically amplified resist composition according to claim 8, wherein the base polymer comprises at least one 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 10】 (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 represents 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 3 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 and 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. d is an integer from 0 to 3.

12. The chemically amplified resist composition according to claim 7, further comprising an organic solvent.

13. The chemically amplified resist composition according to claim 7, further comprising a quencher.

14. 8. The chemically amplified resist composition according to claim 7, further comprising a photoacid generator other than the photoacid generator according to claim 6.

15. The chemically amplified resist composition according to claim 7, further comprising a surfactant.

16. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to claim 7; exposing the resist film to high-energy radiation; and developing the exposed resist film using a developer.

17. 17. The method for forming a pattern according to claim 16, 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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