Photoacid generator, chemically amplified resist composition, and pattern forming method

Abstract

To provide a chemically amplified resist composition which is excellent in balance of sensitivity, CDU, LWR, MEF and DOF in photolithography using high-energy rays as a light source and can form a rectangular pattern, a photoacid generator used therefor, and a pattern forming method using the resist composition.SOLUTION: The photoacid generator is an onium salt compound which comprises an anion containing an iodine atom-substituted aromatic group and two sulfonate groups, and a sulfonium cation or an iodonium cation. The chemically amplified resist composition contains the photoacid generator.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photoacid generator, a chemically amplified resist composition, and a pattern forming method. [Background technology]

[0002] In recent years, the increasing integration and speed of LSIs has led to rapid advances in miniaturization of pattern rules. In particular, logic devices are mass-produced using the multi-patterning lithography process using ArF lithography. To achieve finer patterns, resist compositions for short-wavelength light such as electron beam (EB) and extreme ultraviolet (EUV) are being investigated. As patterns become finer, improvements in lithography performance, such as pattern shape, contrast, line pattern edge roughness (LWR), and hole pattern dimensional uniformity (CDU), are becoming increasingly important.

[0003] In resist compositions using photoacid generators, the diffusion of acid generated by exposure within the resist film significantly affects lithography performance. Measures to suppress acid diffusion include introducing bulky substituents or polar groups into the photoacid generator or increasing its molecular weight. Patent Documents 1 and 2 disclose photoacid generators having a bissulfonium cation, while Patent Documents 3, 4, and 5 propose photoacid generators consisting of a bissulfonium salt having a bissulfonate anion. However, these bissulfonium salts have low solvent solubility and sensitivity, limiting their use in amount. Furthermore, they may potentially cause surface defects, as described below.

[0004] In addition to the aforementioned lithography performance, there is a growing need to improve resist pattern defects, such as scum, bubbles, dust, and bridges between resist patterns after development. One of the causes of these defects is low solubility in the casting solvent and insoluble residues after development.

[0005] To maximize the benefits of shorter wavelength light sources and improve lithography performance, it is extremely important to suppress acid diffusion by optimizing the structure of photoacid generators and improve solvent solubility. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3773139 [Patent Document 2] Japanese Patent Application Publication No. 2019-194178 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-013551 [Patent Document 4] International Publication No. 2011 / 048919 [Patent Document 5] Japanese Patent Application Laid-Open No. 2015-206932 Summary of the Invention [Problem to be solved by the invention]

[0007] Conventional photoacid generators do not necessarily satisfy the lithography performance such as sensitivity, acid diffusion length, solvent solubility, and development contrast required for forming high-resolution resist patterns, which have been demanded in recent years.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a chemically amplified resist composition that exhibits an excellent balance of sensitivity, CDU, LWR, mask error factor (MEF), and depth of focus (DOF) and is capable of forming rectangular patterns in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, EB, or EUV as a light source; a photoacid generator used therein; and a pattern formation method that uses the resist composition. [Means for solving the problem]

[0009] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered that a chemically amplified resist composition using an onium salt compound having a specific structure as a photoacid generator is excellent in lithography performance such as sensitivity, LWR, MEF, CDU, etc., and is extremely effective for precise microfabrication, which has led to the completion of the present invention.

[0010] That is, the present invention provides the following photoacid generator, chemically amplified resist composition, and pattern forming method. 1. A photoacid generator which is an onium salt compound consisting of a sulfonium cation or an iodonium cation and an anion containing an aromatic group substituted with an iodine atom and two sulfonate groups. 2. The photoacid generator according to 1, wherein the onium salt compound is represented by the following formula (1): [ka] (In the formula, X is a trivalent hydrocarbon group having 1 to 35 carbon atoms which may contain a heteroatom. R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 1 and R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached, and R 3 and R 4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R f1 , R f2 , R f3 and R f4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but R f1 and R f2 At least one of R is a fluorine atom or a trifluoromethyl group. f3 and R f4 At least one of the groups is a fluorine atom or a trifluoromethyl group. m 1 and m2 are each independently an integer of 1 to 4. n 1 and n 2 are each independently an integer of 0 to 4. L a1 and L a2 are each independently an ether bond, an ester bond, a sulfonate ester bond, or a carbonate bond. L c1 and L c2 are each independently a single bond or a hydrocarbylene group having 1 to 15 carbon atoms, and a hydrogen atom in the hydrocarbylene group may be substituted with a group containing a hetero atom, and some of the -CH2- in the hydrocarbylene group may be substituted with -O- or -C(=O)-. L b1 , L b2 and L b3 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. Ar is a (p+1)-valent aromatic group having 3 to 15 carbon atoms, and a hydrogen atom in the aromatic group may be substituted with a fluorine atom, a hydroxy group, or a hydrocarbyl group having 1 to 15 carbon atoms. In addition, a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a portion of -CH2- in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -N(R N )-. R N represents a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -S(=O)2-. p is an integer satisfying the condition 1≦p≦5. Za + and Zb + are each independently a sulfonium cation or an iodonium cation. 3. The photoacid generator according to 2, wherein the onium salt compound is represented by the following formula (1a): [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , R f1 , R f2 , R f3 , R f4 , L a1 , L a2 , L b3 , Ar, m 1 , m 2 , n 1 , n 2 ,p,Za + and Zb + is the same as above. A 1 , A 2 and A 3 are each independently a single bond or a hydrocarbylene group having 1 to 8 carbon atoms which may contain a heteroatom, and some of the -CH2- in the hydrocarbylene group may be substituted with -O- or -C(=O)-. A 4 represents a hydrogen atom, a hydroxy group, or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with -O- or -C(=O)-. L b1 ' and L b2 Each of the ' is independently an ether bond, an ester bond, a sulfonate ester bond, or a carbamate bond which is a carbonate bond. L c1 ' and L c2 Each of the ' is independently a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbylene group may be substituted with a group containing a hetero atom, and some of the -CH2- in the hydrocarbylene group may be substituted with -O- or -C(=O)-. 4. The photoacid generator according to 3, wherein the onium salt compound is represented by the following formula (1b): [ka] (In the formula, A 1 , A2 , A 3 , A 4 , L b1 ', L b2 ', L b3 , Za + and Zb + is the same as above. p and q are integers satisfying the following conditions: 1≦p≦5, 0≦q≦4, and 1≦q+p≦5. R f5 and R f6 are each independently a hydrogen atom or a trifluoromethyl group. L a1 ' and L a2 Each of the ' is independently an ether bond or an ester bond. R 5 is a hydroxy group, a fluorine atom, or a hydrocarbyl group having 1 to 15 carbon atoms, in which a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a part of -CH2- in the hydrocarbyl group is replaced with -O-, -C(=O)-, or -N(R N )-. R N is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a portion of -CH2- in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -S(=O)2-. When q is 2 or more, multiple R 5 may be the same or different, and two R 5 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are attached. 5. The photoacid generator according to 4, wherein the onium salt compound is represented by the following formula (1c): [ka] (In the formula, A 3 , L a1 ', L a2 ', L b3 , R 5 , R f5 , R f6 , p, q, Za + and Zb + is the same as above. L b4 and L b5 are each independently an ether bond or an ester bond. A 5 and A 6 are each independently a linear hydrocarbylene group having 1 to 4 carbon atoms. A 7 is a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 8 carbon atoms. Ring W 1 and Ring W 2 are each independently an alicyclic hydrocarbon group having 3 to 10 carbon atoms which may contain a heteroatom. 6.Za + and Zb + are each independently a cation represented by the following formula (Z-1) or (Z-2): [ka] (In the formula, R Z1 , R Z2 and R Z3 are each independently a halogen atom, a hydroxy group, or a hydrocarbyl group having 1 to 15 carbon atoms, a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a part of -CH2- in the hydrocarbyl group is substituted with -O-, -C(=O)-, -S-, -S(=O)-, -S(=O)2-, or -N(R N )-. L is a single bond, -CH2-, -O-, -C(=O)-, -S-, -S(=O)-, -S(=O)2- or -N(R N )-. R N represents a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and some of the -CH2- groups in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -S(=O)2-. x, y, and z each independently represent an integer of 0 to 5. When x is 2 or more, each R Z1 may be the same or different, and two RZ1 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. When y is 2 or more, each R Z2 may be the same or different, and two R Z2 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. When z is 2 or more, each R Z3 may be the same or different, and two R Z3 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are attached. 7. A photoacid generator according to any one of 2 to 6, wherein p is an integer satisfying 1≦p≦3. 8. A chemically amplified resist composition comprising (A) a photoacid generator according to any one of 1 to 7, (B) a base polymer whose solubility in a developer changes under the action of an acid, and (C) an organic solvent. 9. The chemically amplified resist composition of 8, wherein the base polymer contains a repeating unit represented by the following formula (a) or a repeating unit represented by the following formula (b): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. Y 2 is a single bond or an ester bond. Y 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 represents a halogen atom, a hydroxy group, a cyano group or a hydrocarbyl group having 1 to 6 carbon atoms, and some of the -CH2- groups in the hydrocarbyl group may be substituted with -O- or -C(=O)-. R 14is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and some of the -CH2- in the alkanediyl group may be substituted with ether bonds or ester bonds. a is 1 or 2, and b is an integer from 0 to 4, provided that 1≦a+b≦5. 10. The chemically amplified resist composition of 9, wherein the base polymer further contains a repeating unit represented by any one of the following formulas (g1) to (g3): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Z 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z 2 is a single bond or an ester bond. Z 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 represents an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, a bromine atom, or an iodine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom, or a hydroxy group. R 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. M - is a non-nucleophilic counterion. 11. The chemically amplified resist composition of any one of 8 to 10, further comprising a quencher. 12. The chemically amplified resist composition according to any one of 8 to 11, further comprising a photoacid generator other than the photoacid generator according to any one of 1 to 7. 13. The chemically amplified resist composition according to any one of 8 to 12, further comprising a surfactant. 14. A pattern forming method comprising the steps of forming a resist film on a substrate using any one of the chemically amplified resist compositions of 8 to 13, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer. 15. The pattern formation method of 14, wherein the exposure is performed by immersion exposure using a liquid having a refractive index of 1.0 or more interposed between the resist film and a projection lens. 16. The pattern formation method according to claim 15, further comprising applying a protective film on the resist film, and then performing immersion exposure by placing the liquid between the protective film and a projection lens. 17. The pattern forming method according to any one of 14 to 16, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, EB or EUV. 18. A pattern formation method 17 in which an alkaline aqueous solution is used as a developer to dissolve exposed areas and obtain a positive pattern in which unexposed areas do not dissolve. 19. A pattern formation method according to claim 17, in which an organic solvent is used as a developer to dissolve the unexposed areas, resulting in a negative pattern in which the exposed areas do not dissolve. 20. The developer is selected from the group consisting of 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, methyl propionate, and propionate. 19. A pattern formation method in which the compound is at least one selected from the group consisting of ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. [Effects of the Invention]

[0011] When a resist composition containing the photoacid generator of the present invention is used to form a pattern, it exhibits excellent lithography performance such as sensitivity, LWR, and CDU, and is extremely effective in forming a fine resist pattern. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a 1H-NMR spectrum of PAG-1 synthesized in Example 1-1. [Figure 2] 1 is a 19F-NMR spectrum of PAG-1 synthesized in Example 1-1. [Figure 3] 1 is a 1H-NMR spectrum of PAG-2 synthesized in Example 1-2. [Figure 4] 1 is a 19F-NMR spectrum of PAG-2 synthesized in Example 1-2. [Figure 5] 1 is a 1H-NMR spectrum of PAG-3 synthesized in Example 1-3. [Figure 6] 1 is a 19F-NMR spectrum of PAG-3 synthesized in Example 1-3. [Figure 7] 1 is a 1H-NMR spectrum of PAG-4 synthesized in Example 1-4. [Figure 8] 19F-NMR spectrum of PAG-4 synthesized in Example 1-4. [Figure 9] 1 is a 1H-NMR spectrum of PAG-5 synthesized in Example 1-5. [Figure 10] 19F-NMR spectrum of PAG-5 synthesized in Example 1-5. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Photoacid generator] The photoacid generator of the present invention is an onium salt compound comprising a sulfonium cation or an iodonium cation and an anion containing an aromatic group substituted with an iodine atom and two sulfonate groups.

[0014] The onium salt compound is preferably one represented by the following formula (1). [ka]

[0015] In formula (1), X represents a trivalent hydrocarbon group having 1 to 35 carbon atoms, which may contain a heteroatom. The trivalent hydrocarbon group may be saturated or unsaturated, and may be linear, branched, or cyclic. Some or all of the hydrogen atoms in the trivalent hydrocarbon group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom. Alternatively, some of the -CH2- groups in the trivalent hydrocarbon group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom. As a result, the trivalent hydrocarbon group may contain a fluorine atom, chlorine atom, bromine atom, iodine atom, hydroxy group, cyano group, carbonyl group, ether bond, ester bond, sulfonate ester bond, carbonate bond, lactone ring, sultone ring, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl group, or the like.

[0016] Specific examples of X include, but are not limited to, the following: In the following formula, the dashed line represents a bond. [ka]

[0017] [ka]

[0018] [ka]

[0019] Among these, the following are particularly preferred. [ka]

[0020] In formula (1), R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 1and R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached, and R 3 and R 4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0021] R 1 , R 2 , R 3 and R 4 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 10 carbon atoms, such as a vinyl group, allyl group, propenyl group, butenyl group or a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 10 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 10 carbon atoms, such as a phenyl group, 4-n-butylphenyl group, 4-tert-butylphenyl group, 2,4-dimethylphenyl group, 2,4,6-trimethylphenyl group or a naphthyl group; aralkyl groups having 7 to 10 carbon atoms, such as a benzyl group, 1-phenylethyl group or a 2-phenylethyl group; and groups obtained by combining these. 1 , R 2 , R 3 and R 4 is preferably a hydrogen atom.

[0022] In addition, some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, nitrogen atom, or halogen atom, or some of the -CH2- groups in the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, sulfur atom, or nitrogen atom, resulting in the hydrocarbyl group containing a fluorine atom, chlorine atom, bromine atom, iodine atom, hydroxy group, cyano group, carbonyl group, ether bond, ester bond, sulfonate ester bond, carbonate bond, lactone ring, sultone ring, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl group, etc. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups having 3 to 10 carbon atoms such as thienyl group; alkoxyphenyl groups such as 2-hydroxyphenyl group, 4-hydroxyphenyl group, 2-methoxyphenyl group, 3-methoxyphenyl group, and 4-methoxyphenyl group; halogenated phenyl groups such as 4-fluorophenyl group and 4-iodophenyl group; and haloalkylphenyl groups such as 4-trifluoromethylphenyl group.

[0023] In formula (1a), R f1 , R f2 , R f3 and R f4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but R f1 and R f2 At least one of R is a fluorine atom or a trifluoromethyl group. f3 and R f4 At least one of the —SO3 groups is a fluorine atom or a trifluoromethyl group. - R attached to the α carbon of the group f1 , R f2 , R f3 and R f4 are preferably all fluorine atoms.

[0024] m 1 and m 2 are each independently an integer of 1 to 4, preferably 1 or 2. 1 and n 2 are each independently an integer of 0 to 4, with 0, 1 or 2 being preferred.

[0025] In formula (1), L a1 and L a2 are each independently an ether bond, an ester bond, a sulfonate ester bond or a carbonate bond, with an ether bond or an ester bond being preferred.

[0026] In formula (1), L c1 and L c2 are each independently a single bond or a hydrocarbylene group having 1 to 15 carbon atoms, in which a hydrogen atom in the hydrocarbylene group may be substituted with a group containing a hetero atom, and a portion of -CH- in the hydrocarbylene group may be substituted with -O- or -C(=O)-. Examples of the group containing a hetero atom include a hydroxy group, a cyano group, and a halogen atom.

[0027] L c1 and L c2 The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include the hydrocarbylene group represented by the formula (I) described later. c1 ' and L c2 Examples of the hydrocarbylene group represented by L' include the same as those exemplified above. c1 and L c2 As the group, a group containing a cyclic group is preferred.

[0028] In formula (1), L b1 , L b2 and L b3 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond, and is preferably an ether bond or an ester bond.

[0029] In formula (1), Ar is a (p+1)-valent aromatic group having 3 to 15 carbon atoms, and a hydrogen atom in the aromatic group may be substituted with a fluorine atom, a hydroxy group, or a hydrocarbyl group having 1 to 15 carbon atoms. In addition, a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a portion of -CH2- in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -N(RN )-. R N is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a heteroatom, and a portion of the -CH2- in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -S(=O)2-. Examples of the group containing a heteroatom include a hydroxy group, a cyano group, and a halogen atom. Ar is preferably an optionally substituted (p+1)-valent aromatic group having 6 to 10 carbon atoms, and more preferably an optionally substituted (p+1)-valent group derived from benzene.

[0030] In formula (1), p is an integer that satisfies 1≦p≦5, and is preferably an integer of 1 to 3.

[0031] In equation (1), Za + and Zb + are each independently a sulfonium cation or an iodonium cation.

[0032] Specific examples of the iodonium cation include diphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-ethylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(4-(1,1-dimethylpropyl)phenyl)iodonium, 4-methoxyphenylphenyliodonium, 4-tert-butoxyphenylphenyliodonium, 4-acryloyloxyphenylphenyliodonium, 4-methacryloyloxyphenylphenyliodonium, 4-fluorophenylphenyliodonium, and [4-(2-methacryloyloxy-ethoxy)phenyl]phenyliodonium, but are not limited to these.

[0033] The sulfonium cation is preferably one represented by the following formula (Z-1) or (Z-2). [ka]

[0034] In formulas (Z-1) and (Z-2), R Z1 , R Z2 and R Z3 are each independently a halogen atom, a hydroxy group, or a hydrocarbyl group having 1 to 15 carbon atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 15 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 cyclic saturated hydrocarbyl groups having 3 to 15 carbon atoms, such as a 2-methyl-2-decanyl group, an adamantyl group, or an adamantylmethyl group; aryl groups having 6 to 15 carbon atoms, such as a phenyl group, a naphthyl group, or an anthracenyl group; or groups obtained by combining these. In addition, hydrogen atoms in the hydrocarbyl groups may be substituted with groups containing heteroatoms, and a portion of -CH2- in the hydrocarbyl groups may be substituted with -O-, -C(=O)-, -S-, -S(=O)-, -S(=O)2-, or -N(R N )-. In addition, the —CH2— in the hydrocarbyl group may be substituted with —CH2—. may be bonded to a carbon atom of an aromatic ring. Examples of the group containing a hetero atom include a hydroxy group, a cyano group, and a halogen atom.

[0035] In formula (Z-2), L is a single bond, -CH2-, -O-, -C(=O)-, -S-, -S(=O)-, -S(=O)2-, or -N(R N )-. R Nis a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a portion of -CH2- in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -S(=O)2-. Examples of the group containing a hetero atom include a hydroxy group, a cyano group, and a halogen atom.

[0036] In formulas (Z-1) and (Z-2), x, y, and z each independently represent an integer of 0 to 5. When x is 2 or more, each R Z1 may be the same or different, and two R Z1 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. When y is 2 or more, each R Z2 may be the same or different, and two R Z2 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. When z is 2 or more, each R Z3 may be the same or different, and two R Z3 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are attached.

[0037] Examples of the sulfonium cation represented by formula (Z-1) include, but are not limited to, those shown below. [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] Examples of the sulfonium cation represented by formula (Z-2) include, but are not limited to, those shown below. [ka]

[0048] [ka]

[0049] The photoacid generator represented by formula (1) is preferably one represented by the following formula (1a). [ka] (In the formula, R 1 , R 2 , R 3 , R4 , R f1 , R f2 , R f3 , R f4 , L a1 , L a2 , L b3 , Ar, m 1 , m 2 , n 1 , n 2 ,p,Za + and Zb + is the same as above.)

[0050] In formula (1a), A 1 , A 2 and A 3 are each independently a single bond or a hydrocarbylene group having 1 to 8 carbon atoms which may contain a heteroatom, and some of the -CH2- groups in the hydrocarbylene group may be replaced with -O- or -C(=O)-. The hydrocarbylene group may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples include alkanediyl groups having 1 to 8 carbon atoms, such as methanediyl, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, and octane-1,8-diyl; cyclic saturated hydrocarbylene groups having 3 to 8 carbon atoms, such as cyclopentanediyl, cyclohexanediyl, and norbornanediyl; and arylene groups having 6 to 8 carbon atoms, such as phenylene. Of these, methanediyl is preferred.

[0051] In formula (1a), A 4is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom, a hydroxy group, or a heteroatom, and some of the -CH2- groups in the hydrocarbyl group may be replaced with -O- or -C(=O)-. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl; cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopentyl, cyclohexyl, norbornyl, and adamantyl; and aryl groups having 6 to 10 carbon atoms, such as phenyl and naphthyl. A 4 is preferably a hydrogen atom, a methyl group, or an ethyl group.

[0052] In formula (1a), L b1 ' and L b2 Each of the ' is independently an ether bond, an ester bond, a sulfonate ester bond, or a carbamate bond which is a carbonate bond. Of these, an ester bond is preferred.

[0053] In formula (1a), L c1 ' and L c2 Each ' is independently a single bond or a hydrocarbylene group having 1 to 10 carbon atoms, and a hydrogen atom of the hydrocarbylene group may be substituted with a group containing a hetero atom, and some of the -CH- in the hydrocarbylene group may be substituted with -O- or -C(=O)-. Examples of the group containing a hetero atom include a hydroxy group, a cyano group, and a halogen atom.

[0054] L c1 ' and L c2The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,2-diyl group, a butane-2,3-butylene group, a butane-1,4-butylene group, a 2,3-dimethyl-2,3-butylene group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a hexane-2,5-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1, 9-diyl group, decane-1,10-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,2-diyl group, cyclohexane-1,3-diyl group, cyclohexane-1,4-diyl group, 4,6-dimethylcyclohexane-1,3-diyl group, cyclooctane-1,4-diyl group, cyclooctane-1,5-diyl group, 1,2-cyclohexanedimethylene group, 1,3-cyclohexanedimethylene group, 1,4-cyclohexanedimethylene group, 1-ethyl-1 ,4-cyclohexanedimethylene group, 2-cyclohexyl-1,3-propylene group, 1,4-cyclooctylene group, 1,5-cyclooctylene group, 1,2-phenylene group, 4-methyl-1,2-phenylene group, 1,3-phenylene group, 2-methyl-1,3-phenylene group, 4-methyl-1,3-phenylene group, 1,4-phenylene group, 2-methyl-1,4-phenylene group, 2-tert-butyl-1,4-phenylene group, 2,3-dimethyl-1,4-phenylene group, Examples thereof include trimethyl-1,4-phenylene group, 4-(methylene)phenyl group, 1,2-benzenedimethylene group, 1,3-benzenedimethylene group, 1,4-benzenedimethylene group, 1,2-naphthylene group, 1,3-naphthylene group, 1,4-naphthylene group, 1,5-naphthylene group, 1,6-naphthylene group, 1,7-naphthylene group, 2,3-naphthylene group, 2,6-naphthylene group, 2,7-naphthylene group, 3,6-naphthylene group, 1,8-naphthalenedimethylene group, etc. Among these, cyclopentane-1,3-diyl group, cyclohexane-1,2-diyl group, cyclohexane-1,3-diyl group, cyclohexane-1,4-diyl group, and 1,2-phenylene group are preferred.

[0055] Among the photoacid generators represented by formula (1a), those represented by the following formula (1b) are more preferred. [ka] (In the formula, A 1 , A 2 , A 3 , A 4 , L b1 ', L b2 ', L b3 , Za + and Zb + is the same as above.)

[0056] In formula (1b), p and q are integers that satisfy 1≦p≦5, 0≦q≦4, and 1≦q+p≦5, and preferably integers that satisfy 1≦p≦3, 0≦q≦4, and 1≦q+p≦5.

[0057] In formula (1b), R f5 and R f6 are each independently a hydrogen atom or a trifluoromethyl group. f5 and R f6 are preferably trifluoromethyl groups.

[0058] In formula (1b), L a1 ' and L a2 Each of the ' is independently an ether bond or an ester bond. Of these, an ester bond is preferred.

[0059] In formula (1b), R 5 is a hydroxy group, a fluorine atom, or a hydrocarbyl group having 1 to 15 carbon atoms, in which a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a part of -CH2- in the hydrocarbyl group is replaced with -O-, -C(=O)-, or -N(R N )-. R Nis a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, and a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and a portion of -CH2- in the hydrocarbyl group may be substituted with -O-, -C(=O)-, or -S(=O)2-. When q is 2 or more, multiple R 5 may be the same or different, and two R 5 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. Examples of the group containing a hetero atom include a hydroxy group, a cyano group, and a halogen atom.

[0060] R 5 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 15 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6]Cyclic saturated hydrocarbyl groups having 3 to 15 carbon atoms such as a decanyl group or an adamantyl group; alkenyl groups having 2 to 15 carbon atoms such as a vinyl group, allyl group, propenyl group, butenyl group or a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 15 carbon atoms such as a cyclohexenyl group; phenyl group, 2-hydroxyphenyl group, 4-hydroxyphenyl group, 2-methoxyphenyl group, 3-methoxyphenyl group, 4-methoxyphenyl group, 4-fluorophenyl group, 4-iodophenyl group Examples of the aryl groups include aryl groups having 6 to 15 carbon atoms, such as a 4-n-butylphenyl group, a 4-tert-butylphenyl group, a 4-tert-butoxyphenyl group, a 4-trifluoromethylphenyl group, a 2,4-dimethylphenyl group, a 2,4,6-trimethylphenyl group, a 2,4,6-triisopropylphenyl group, and a naphthyl group; aralkyl groups having 7 to 15 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these groups. 5 is preferably a hydroxy group or a methyl group.

[0061] Among the photoacid generators represented by formula (1b), those represented by the following formula (1c) are more preferred. [ka] (In the formula, A 3 , L a1 ', L a2 ', L b3 , R 5 , R f5 , R f6 , p, q, Za + and Zb + is the same as above.)

[0062] In formula (1c), L b4 and L b5 are each independently an ether bond or an ester bond. Of these, an ester bond is preferred.

[0063] In formula (1c), A 5 and A 6 are each independently a linear hydrocarbylene group having 1 to 4 carbon atoms. 5and A 6 As the alkyl group, a methylene group or an ethylene group is preferred.

[0064] In formula (1c), A 7 is a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 8 carbon atoms. 7 is preferably a hydrogen atom or a hydroxy group.

[0065] In formula (1c), ring W 1 and Ring W 2 are each independently an alicyclic hydrocarbon group having 3 to 10 carbon atoms which may contain a heteroatom. Specific examples of the alicyclic hydrocarbon group include alicyclic saturated hydrocarbon groups having 6 to 10 carbon atoms such as a cyclohexanediyl group, a cycloheptanediyl group, and a cyclooctanediyl group; and aromatic hydrocarbon groups having 6 to 10 carbon atoms such as a phenylene group, a xylylene group, and a naphthylene group. 1 and Ring W 2 is preferably an alicyclic saturated hydrocarbon group having 6 to 10 carbon atoms.

[0066] The photoacid generator of the present invention is a compound represented by formula (1c), + and Zb + are preferably sulfonium cations represented by formula (Z-1) or (Z-2).

[0067] Examples of anions of the onium salt compound represented by formula (1) include, but are not limited to, those shown below: In the following formula, Me is a methyl group, p and q are integers satisfying 1≦p≦5, 0≦q≦4, and 1≦q+p≦5, and s and t are integers satisfying 1≦s≦4, and 1≦t≦4. [ka]

[0068] [ka]

[0069]

change

[0070]

change

[0071]

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[0072]

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[0073]

change

[0074]

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[0075]

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[0076]

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

change

[0082]

change

[0083]

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[0084]

change

[0085]

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[0086]

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[0087]

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[0088]

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[0089]

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[0090]

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[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] Specific structures of the photoacid generator of the present invention include combinations of the specific anions and specific cations described above, but the photoacid generator of the present invention is not limited to these.

[0098] Among these, the following are particularly preferred. [ka]

[0099] In the formula, Z + is a sulfonium cation represented by any of the following formulas: [ka]

[0100] The onium salt compound represented by formula (1) can be, for example, L b1 and L b2 is an ester bond, and Za + and Zb + can be synthesized according to the following scheme. [ka] (In the formula, X, R 1 , R 2 , R 3 , R 4 , R f1 , R f2 , R f3 , R f4 , m 1 , m 2 , n 1 , n 2 , L a1 , L a2 , L c1 , L c2 , L b3 ,Ar,p,Za + is the same as above.)

[0101] In the first step, acid chloride B is synthesized by reacting carboxylic acid sulfonium salt A with oxalyl chloride.

[0102] In the second step, the acid chloride B is reacted with the diol C in the presence of a base to carry out esterification, thereby synthesizing the target compound D. The base that can be used is pyridine or the like.

[0103] Alternatively, the starting cation can be synthesized according to the above scheme using an alkali metal salt such as sodium or potassium, or an ammonium salt, and then converted to the desired cation species by an ion exchange reaction. Ion exchange can be performed by a known method, for example, see JP-A-2007-145797.

[0104] The above-described manufacturing methods are merely examples and are not limiting.

[0105] The photoacid generator of the present invention is characterized by a specific bis-sulfonate structure containing one or more iodine atoms in the anion. The resist composition containing the photoacid generator of the present invention has a significantly high acid diffusion suppression ability, and as a result, various resist performances, particularly LWR, CDU, and MEF, can be improved. This is presumably due to the highly polar structure having two salt structures in one molecule. In addition, when a cyclic group is contained, the bulky structure of the cyclic group and original It is believed that the inclusion of a large molecular weight iodine atom can suppress the acid diffusion length, resulting in good CDU and LWR. While Japanese Patent Publication No. 3773139 describes a resist composition containing a bissulfonium cation, the polarity of the anion in this case is the same as that of conventional monosulfonium salts, and therefore the acid diffusion suppression ability is not as good as that of the photoacid generator of the present invention, and satisfactory lithography performance has not yet been achieved.

[0106] Japanese Patent Laid-Open Publication No. 2008-013551 and International Publication No. 2011 / 048919 disclose resist compositions containing photoacid generators having a bissulfonate anion. However, bis-onium salts generally have low solubility in organic solvents due to their high polarity. This property raises concerns about the possibility of coating defects, leaching into water during immersion lithography, and other associated defects. On the other hand, the photoacid generator of the present invention has fewer of the aforementioned defects because the cyclic group contained in the molecule contributes to improved lipophilicity before the acid elimination reaction, making it extremely useful as a material for resist compositions.

[0107] Furthermore, Japanese Patent Application Laid-Open No. 2015-206932 also describes a resist composition containing a similar photoacid generator, but due to its low sensitivity, there are concerns about film residue during development. On the other hand, the photoacid generator of the present invention has an iodine atom in its molecule, which significantly enhances absorption of EUV light at a wavelength of 13.5 nm. This generates secondary electrons from the iodine atom during exposure, resulting in higher sensitivity than conventional monoonium salts or conventional bissulfonium salts. Therefore, it is possible to achieve a well-balanced improvement in sensitivity and roughness, which have traditionally been in a trade-off relationship. For these reasons, the photoacid generator of the present invention is highly useful for forming resist patterns using EUV lithography.

[0108] [Chemically amplified resist composition] The chemically amplified resist composition of the present invention comprises: (A) a photoacid generator represented by formula (1), (B) a base polymer whose solubility in a developer changes upon the action of an acid, and (C) Organic solvent Contains as an essential ingredient.

[0109] In the chemically amplified resist composition of the present invention, the content of the photoacid generator (A), component, is preferably 0.1 to 40 parts by mass, more preferably 1 to 20 parts by mass, per 80 parts by mass of the base polymer (B), described below. When the content of the photoacid generator (A), component, is within the above range, it functions satisfactorily as a photoacid generator, and there is no risk of reduced sensitivity or the generation of foreign matter due to insufficient solubility. The photoacid generator (A) may be used singly or in combination of two or more types.

[0110] [(B) Base polymer] The base polymer of component (B) is preferably a polymer containing a repeating unit represented by the following formula (a) (hereinafter also referred to as repeating unit a) or a repeating unit represented by the following formula (b) (hereinafter also referred to as repeating unit b). [ka]

[0111] In formulas (a) and (b), R A are each independently a hydrogen atom or a methyl group. 1 Y is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. 2 is a single bond or an ester bond. 3 is a single bond, an ether bond, or an ester bond. 11 and R 12 are each independently an acid labile group. When the base polymer contains both repeating units a and b, R 11 and R 12 may be the same or different. 13 R is a halogen atom, a hydroxy group, a cyano group, or a hydrocarbyl group having 1 to 6 carbon atoms, and some of the -CH2- in the hydrocarbyl group may be substituted with -O- or -C(=O)-. 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and some of the -CH2- groups in the alkanediyl group may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer of 0 to 4, with the proviso that 1≦a+b≦5.

[0112] Examples of monomers that provide the repeating unit a include, but are not limited to, the following: A and R 11 is the same as above. [ka]

[0113] Examples of the monomer that provides the repeating unit b include, but are not limited to, the following: A and R 12 is the same as above. [ka]

[0114] In formulas (a) and (b), R 11 and R 12 Examples of the acid labile group represented by the formula (I) include those described in JP-A Nos. 2013-80033 and 2013-83821.

[0115] Typical examples of the acid labile group include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0116] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 40 carbon atoms, more preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms.

[0117] In formula (AL-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferred.

[0118] 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 heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0119] In formula (AL-3), R L5 , R L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L5 , R L6 and R L7 Any two of these may be bonded to each other to form, together with the carbon atoms to which they are bonded, a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0120] The base polymer may contain a repeating unit c containing a phenolic hydroxy group as an adhesive group. Examples of monomers that provide the repeating unit c include, but are not limited to, the following. In the following formula, R A is the same as above. [ka]

[0121] [ka]

[0122] [ka]

[0123] The base polymer may contain a repeating unit d containing, as another adhesive group, a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonate ester bond, a carbonyl group, a sulfonyl group, a cyano group, or a carboxy group. Examples of monomers that provide the repeating unit d include, but are not limited to, those shown below. In the following formula, RA is the same as above. [ka]

[0124] [ka]

[0125] [ka]

[0126] [ka]

[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] The base polymer may include a repeating unit e derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or a derivative thereof. Examples of monomers that provide the repeating unit e include, but are not limited to, the following: [ka]

[0135] The base polymer may include repeat units f derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindane, vinylpyridine, or vinylcarbazole.

[0136] The base polymer may contain a repeating unit g derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units g include a repeating unit represented by the following formula (g1) (hereinafter also referred to as repeating unit g1), a repeating unit represented by the following formula (g2) (hereinafter also referred to as repeating unit g2), and a repeating unit represented by the following formula (g3) (hereinafter also referred to as repeating unit g3). The repeating units g1 to g3 may be used alone or in combination of two or more. [ka]

[0137] In formulas (g1) to (g3), R A are each independently a hydrogen atom or a methyl group. 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 11Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 represents an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, a bromine atom, or an iodine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a halogen atom, or a hydroxy group.

[0138] In formulas (g1) to (g3), R 21 ~R 28 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (2) described below. 101 ~R 103Examples of the hydrocarbyl group include those exemplified in the description of (1). 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- groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is the same as that shown in R 101 and R 102 and the sulfur atom to which they are bonded to form a ring, the same rings as those exemplified above can be mentioned.

[0139] In formula (g1), M - is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0140] Other examples of the non-nucleophilic counter ion include a sulfonate ion represented by the following formula (g1-1) in which the α-position is substituted with a fluorine atom, and a sulfonate ion represented by the following formula (g1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group. [ka]

[0141] In formula (g1-1), R 31 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and the hydrocarbyl group may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0142] In formula (g1-2), R 32 is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbyl carbonyl group having 6 to 20 carbon atoms, and the hydrocarbyl group and the hydrocarbyl carbonyl group may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl moiety of the hydrocarbyl group and the hydrocarbyl carbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A') described below. 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0143] Examples of the cation of the monomer that gives the repeating unit g1 include, but are not limited to, the following: A is the same as above. [ka]

[0144] Examples of the cation of the monomer that gives the repeating unit g2 or g3 include the same cations as those exemplified as the cation of the sulfonium salt represented by formula (2) described below.

[0145] Examples of the anion of the monomer that gives the repeating unit g2 include, but are not limited to, the following: A is the same as above. [ka]

[0146] [ka]

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157] Examples of the anion of the monomer that gives the repeating unit g3 include, but are not limited to, those shown below. A is the same as above. [ka]

[0158] By bonding the acid generator to the polymer main chain, acid diffusion is reduced, preventing a decrease in resolution due to blurring of the acid diffusion. Furthermore, uniform dispersion of the acid generator improves LWR and CDU. When using a base polymer containing repeating unit g (i.e., a polymer-bound acid generator), the addition of the additive acid generator described below can be omitted.

[0159] The base polymer for the positive resist composition essentially contains the repeating unit a or b containing an acid-labile group. In this case, the content ratios of the repeating units a, b, c, d, e, f, and g are preferably 0≦a<1.0, 0≦b<1.0, 0<a+b<1.0, 0≦c≦0.9, 0≦d≦0.9, 0≦e≦0.8, 0≦f≦0.8, and 0≦g≦0.5, more preferably 0≦a≦0.9, 0≦b≦0.9, 0.1≦a+b≦0.9, 0≦c≦0.8, 0≦d≦0.8, 0≦e≦0.7, 0≦f≦0.7, and 0≦g≦0.4, and still more preferably 0≦a≦0.8, 0≦b≦0.8, 0.1≦a+b≦0.8, 0≦c≦0.75, 0≦d≦0.75, 0≦e≦0.6, 0≦f≦0.6, and 0≦g≦0.3. When the repeating unit g is at least one selected from the repeating units g1 to g3, g = g1 + g2 + g3. Also, a + b + c + d + e + f + g = 1.0.

[0160] On the other hand, the base polymer for the negative resist composition does not necessarily require an acid-labile group. Examples of such a base polymer include those containing the repeating unit c and optionally further containing the repeating units d, e, f, and / or g. The content ratios of these repeating units are preferably 0<c≦1.0, 0≦d≦0.9, 0≦e≦0.8, 0≦f≦0.8, and 0≦g≦0.5, more preferably 0.2≦c≦1.0, 0≦d≦0.8, 0≦e≦0.7, 0≦f≦0.7, and 0≦g≦0.4, and still more preferably 0.3≦c≦1.0, 0≦d≦0.75, 0≦e≦0.6, 0≦f≦0.6, and 0≦g≦0.3. When the repeating unit g is at least one selected from the repeating units g1 to g3, g = g1 + g2 + g3. Also, c + d + e + f + g = 1.0.

[0161] To synthesize the base polymer, for example, a monomer that provides the above-described repeating unit may be heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0162] Examples of organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, and more preferably 5 to 20 hours.

[0163] When a monomer containing a hydroxy group is copolymerized, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid, such as an ethoxyethoxy group, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0164] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by the alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

[0165] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0166] The base polymer preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) using THF as a solvent of 1,000 to 500,000, more preferably 2,000 to 30,000. When the Mw is within this range, the resist film has good heat resistance and solubility in an alkaline developer.

[0167] Furthermore, if the base polymer has a broad molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers may result in the appearance of foreign matter on the pattern after exposure, or the pattern shape may be deteriorated. As the pattern rule becomes finer, the effects of Mw and Mw / Mn tend to become greater, so in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the Mw / Mn of the base polymer has a narrow distribution of 1.0 to 2.0, and particularly 1.0 to 1.5.

[0168] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0169] [(C) Organic solvent] The organic solvent of component (C) used in the present invention may be any organic solvent that can dissolve the base polymer, photoacid generator, quencher, other additives, etc. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone described in paragraphs

[0144] and

[0145] of JP-A No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether. Examples of suitable organic solvents include ethers such as propylene glycol dimethyl ether and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; and lactones such as γ-butyrolactone. When an acetal-based acid labile group is used, a high-boiling alcohol solvent, specifically, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, or the like, can be added to accelerate the deprotection reaction of the acetal. Among these organic solvents, 1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate, cyclohexanone, γ-butyrolactone, and mixed solvents thereof are preferred, as they have particularly excellent solubility for acid generators.

[0170] In the chemically amplified resist composition of the present invention, the content of the organic solvent of component (C) is preferably 200 to 7,000 parts by mass, and more preferably 400 to 5,000 parts by mass, per 80 parts by mass of the base polymer (B). The organic solvent (C) may be used alone or in combination of two or more.

[0171] [(D) Photoacid generator other than the photoacid generator represented by formula (1)] The chemically amplified resist composition of the present invention may also include, as component (D), a photoacid generator other than the photoacid generator of component (A) (hereinafter also referred to as "other photoacid generator").

[0172] As other photoacid generators, those represented by the following formula (2) are preferred. [ka]

[0173] In formula (2), R 101 , R 102 and R 103 are each independently a linear, branched or cyclic alkyl or alkenyl group having 1 to 10 carbon atoms, which may be substituted with a heteroatom or may be interrupted by a heteroatom, or an aryl or aralkyl group having 6 to 18 carbon atoms, which may be substituted with a heteroatom or may be interrupted by 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 attached.

[0174] Examples of the cation of the sulfonium salt represented by formula (2) include the same as those exemplified as the sulfonium cation represented by formula (Z-1) and the sulfonium cation represented by formula (Z-2).

[0175] In formula (2), Xa - is an anion selected from the following formulae (2A) to (2D). [ka]

[0176] In formula (2A), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (2A') described below.111 Examples include those similar to those exemplified in the explanation of .

[0177] The anion represented by formula (2A) is preferably one represented by the following formula (2A'). [ka]

[0178] In formula (2A'), R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group.

[0179] In formula (2A'), R 111 is a hydrocarbyl group having 1 to 30 carbon atoms which may contain a hetero atom. From the viewpoint of obtaining high resolution in the formation of fine patterns, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

[0180] R 111 The hydrocarbyl group having 1 to 30 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 30 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and icosyl groups; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, and nonyl. Examples of the alkyl group include saturated cyclic hydrocarbyl groups having 3 to 30 carbon atoms, such as a carboxymethyl group, a tricyclodecanyl group, a tetracyclododecanyl group, a tetracyclododecanylmethyl group, and a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 30 carbon atoms, such as an allyl group and a 3-cyclohexenyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; aralkyl groups having 7 to 30 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these groups.

[0181] In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH- constituting the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, resulting in the hydrocarbyl group containing 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, etc. The heteroatom is preferably an oxygen atom. Examples of hydrocarbyl groups containing hetero atoms include tetrahydrofuryl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclohexyl groups.

[0182] The synthesis of sulfonium salts having an anion represented by formula (2A') is described in detail in JP-A Nos. 2007-145797, 2008-106045, 2009-7327, and 2009-258695. Sulfonium salts described in JP-A Nos. 2010-215608, 2012-41320, 2012-106986, and 2012-153644 are also suitable.

[0183] Examples of the anion represented by formula (2A) include, but are not limited to, those shown below: In the following formula, Ac is an acetyl group. [ka]

[0184] [ka]

[0185] [ka]

[0186] In formula (2B), 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. Specific examples thereof include those represented by the formula ( 2 R in A') 111 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 are bonded to each other and form the bonded group (-CF2-SO2-N - -SO2-CF2-) together to form a ring, in which case, R fb1 and R fb2 The group obtained by bonding these groups together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0187] In formula (2C), 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. Specific examples thereof include those represented by the formula ( 2 R in A') 111 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fc1 , R fc2 and R fc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are bonded to each other and form the bonded group (-CF2-SO2-C - -SO2-CF2-) together to form a ring, in which case, R fc1 and R fc2The group obtained by bonding these groups together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0188] In formula (2D), 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 those represented by the formula ( 2 R in A') 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0189] The synthesis of sulfonium salts containing anions represented by formula (2D) is described in detail in JP-A-2010-215608.

[0190] Examples of the anion represented by formula (2D) include, but are not limited to, those shown below. [ka]

[0191] Although the photoacid generator containing the anion represented by formula (2D) does not have a fluorine atom at the α-position of the sulfo group, it has two trifluoromethyl groups at the β-position, and therefore has sufficient acidity to cleave the acid labile groups in the base polymer, making it suitable for use as a photoacid generator.

[0192] Among the above photoacid generators, those containing an anion represented by formula (2A') or (2D) are particularly preferred because they have small acid diffusion and excellent solubility in solvents.

[0193] In the chemically amplified resist composition of the present invention, the content of the (D) other photoacid generator is 0 to 40 parts by mass relative to 80 parts by mass of the (B) base polymer, but when included, it is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 20 parts by mass. If the content of the (D) other photoacid generator is within the above range, there is no risk of degradation of resolution or problems with foreign matter occurring after development of the resist film or during stripping. The (D) other photoacid generators may be used alone or in combination of two or more.

[0194] [(E) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (E). A quencher is a compound that can suppress the diffusion rate of the acid generated from the photoacid generator when it diffuses into the resist film.

[0195] Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. Particularly preferred are the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

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

[0196] Further examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids not fluorinated at the α-position, as described in JP 2008-158339 A, and carboxylic acids as described in JP 3991462 A. However, these salts are conjugate bases of weak acids as counter anions. The term "weak acid" as used herein refers to an acid that exhibits an acidity that is insufficient to deprotect the acid labile groups of the acid labile group-containing units contained in the base polymer. The onium salts function as quenchers when used in combination with an onium salt-type photoacid generator having a counter anion that is a conjugate base of a strong acid, such as a sulfonic acid fluorinated at the α-position.

[0197] That is, when an onium salt that generates a strong acid, such as a sulfonic acid fluorinated at the α-position, is mixed with an onium salt that generates a weak acid, such as a non-fluorinated sulfonic acid or carboxylic acid, the strong acid generated from the photoacid generator upon irradiation with high-energy rays collides with an onium salt having an unreacted weak acid anion, releasing the weak acid through salt exchange and generating an onium salt having a strong acid anion. In this process, the strong acid is exchanged for a weak acid with lower catalytic activity, and the acid appears to be deactivated, thereby enabling control of acid diffusion.

[0198] 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 the weak acid generated by irradiation with high-energy rays collides with the unreacted onium salt that generates the strong acid, and salt exchange cannot occur. This is due to the phenomenon that the onium cation more easily forms an ion pair with the anion of the strong acid.

[0199] Examples of such quenchers include a compound represented by the following formula (3) (onium salt of sulfonic acid not fluorinated at the α-position) and a compound represented by the following formula (4) (onium salt of carboxylic acid). [ka]

[0200] In formula (3), R 201 represents a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group.

[0201] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as decanyl group, adamantyl group, and adamantylmethyl group; C2 to 40 alkenyl groups such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; C3 to 40 unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, aryl groups having 6 to 40 carbon atoms such as aryl groups (e.g., 4-n-butylphenyl group), dialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), and dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group); aralkyl groups having 7 to 40 carbon atoms such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group; and groups obtained by combining these.

[0202] Furthermore, some or all of the hydrogen atoms in 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, or some of the -CH- in 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, etc. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0203] In formula (4), R 202 R is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. 202 Examples of the hydrocarbyl group represented by R 201

[0039] Other specific examples include fluorine-containing alkyl groups such as a trifluoromethyl group, a trifluoroethyl group, a 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and a 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group; and fluorine-containing aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0204] An onium salt having a nitrogen-containing substituent may also be used in combination. Such a compound functions as a quencher in the unexposed area, and loses its quenching ability in the exposed area by neutralizing with the acid generated by the compound itself, functioning as a so-called photodegradable base. The use of a photodegradable base can further enhance the contrast between the exposed and unexposed areas. For example, JP-A Nos. 2009-109595 and 2012-46501 can be used as references for the photodegradable base.

[0205] In equations (3) and (4), Mq + is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. As the sulfonium cation and the iodonium cation, Za in formula (1) + and Zb + Examples of the sulfonium cation and iodonium cation represented by the following formula include the same as those exemplified above.

[0206] As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (5) can also be suitably used. [ka]

[0207] In formula (5), R 301 represents a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, in which some or all of the hydrogen atoms may be substituted with halogen atoms, or -N(R 301A )-C(=O)-R 301B or -N(R 301A )-C(=O)-OR 301B R 301Ais a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 301B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. A is a single bond or a (z'+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When z' is 2 or more, each R 301 may be the same or different from each other.

[0208] In formula (5), R 302 , R 303 and R 304 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Some or all of the hydrogen atoms in the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone group, a sulfone group, or a sulfonium salt-containing group. Some of the -CH2- groups in the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. Furthermore, R 302 , R 303 and R 304 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0209] In formula (5), x' is an integer of 1 to 5. y' is an integer of 0 to 3. z' is an integer of 1 to 3.

[0210] Specific examples of the compound represented by formula (5) include those described in JP 2017-219836 A. Iodine atoms have high absorption of EUV light with a wavelength of 13.5 nm, which generates secondary electrons during exposure, and the energy of the secondary electrons is transferred to the acid generator, accelerating the decomposition of the quencher, thereby improving sensitivity.

[0211] Further examples of the quencher include the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has the effect of preventing pattern film loss and pattern top rounding when a protective film for immersion lithography is applied.

[0212] When the chemically amplified resist composition of the present invention contains a quencher (E), the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, per 80 parts by mass of the base polymer. Adding a quencher not only facilitates adjustment of the sensitivity of the resist film, but also suppresses the diffusion rate of acid in the resist film, improving resolution, suppressing changes in sensitivity after exposure, reducing dependency on the substrate and environment, and improving exposure latitude and pattern profile. The addition of these quenchers can also improve substrate adhesion. The quenchers (E) may be used alone or in combination of two or more.

[0213] [(F) Surfactant] The chemically amplified resist composition of the present invention may further comprise a surfactant (F). The surfactant (F) is preferably a surfactant that is insoluble or slightly soluble in water but soluble in an alkaline developer, or a surfactant that is insoluble or slightly soluble in both water and an alkaline developer. Examples of such surfactants include those described in JP-A-2010-215608 and JP-A-2011-16746.

[0214] Among the surfactants described in the above publications, preferred surfactants that are insoluble or slightly 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 oxetane ring-opening polymers represented by the following formula (surf-1): [ka]

[0215] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), regardless of the above descriptions. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the divalent aliphatic group include an ethylene group, a 1,4-butylene group, a 1,2-propylene group, a 2,2-dimethyl-1,3-propylene group, and a 1,5-pentylene group, and examples of the trivalent or tetravalent aliphatic group include the following: [ka] (In the formula, the dashed lines indicate bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0216] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferred.

[0217] 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 structural units in formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of partially fluorinated oxetane ring-opening polymer surfactants is described in detail in the specification of U.S. Pat. No. 5,650,483, etc.

[0218] Surfactants that are insoluble or slightly soluble in water but soluble in alkaline developers have the function of reducing water penetration and leaching by orienting themselves on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, they are useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure equipment. Furthermore, they are useful because they become soluble during alkaline aqueous development after exposure (post-exposure bake) and are less likely to become contaminants that cause defects. Such surfactants are insoluble or slightly soluble in water but soluble in alkaline developers. They are also called hydrophobic resins, and are particularly preferred because they have high water repellency and improve water slippage.

[0219] Such polymer surfactants include those containing at least one repeating unit selected from those represented by any of the following formulae (6A) to (6E). [ka]

[0220] In formulas (6A) to (6E), R B is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 3 is -CH2-, -CH2CH2-, -O- or two -H groups separated from each other. s1are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 R are each independently a hydrogen atom, a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group. s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. s4 is a hydrocarbon group or a fluorinated hydrocarbon group having 1 to 20 carbon atoms and a valence of (u+1). u is an integer of 1 to 3. R s5 are each independently a hydrogen atom or -C(=O)-OR s7 R s7 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.

[0221] R s1 The hydrocarbyl group represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, an n-pentyl group, a cyclopentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an adamantyl group, a norbornyl group, etc. Among these, those having 1 to 6 carbon atoms are preferred.

[0222] R s2 The hydrocarbylene group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group.

[0223] R s3 or R s6The hydrocarbyl group represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkyl groups, alkenyl groups, and alkynyl groups, with alkyl groups being preferred. s1 In addition to the examples of the hydrocarbyl group represented by the formula (R), examples include an n-undecyl group, an n-dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group. s3 or R s6 Examples of the fluorinated hydrocarbyl group represented by the formula (I) include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbyl group have been substituted with fluorine atoms. As mentioned above, an ether bond or a carbonyl group may be present between these carbon-carbon bonds.

[0224] R s3 Examples of the acid labile group represented by the formula (AL-1) to (AL-3) include the groups represented by the formulas (AL-1) to (AL-3) above, tertiary hydrocarbyl groups having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and oxoalkyl groups having 4 to 20 carbon atoms.

[0225] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include groups obtained by further eliminating u hydrogen atoms from the aforementioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0226] R s7The fluorinated hydrocarbyl group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include those in which some or all of the hydrogen atoms of the hydrocarbyl group have been substituted with fluorine atoms. 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, 2,2,3,3,4,4,4-heptafluorobutyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, 2-(perfluorobutyl)ethyl group, 2-(perfluorohexyl)ethyl group, 2-(perfluorooctyl)ethyl group, 2-(perfluorodecyl)ethyl group, and the like.

[0227] Examples of the repeating unit represented by any one of formulas (6A) to (6E) include, but are not limited to, the following: B is the same as above. [ka]

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] [ka]

[0232] The polymer surfactant may further contain other repeating units in addition to the repeating units represented by formulae (6A) to (6E). Examples of such 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 (6A) to (6E) is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %, of all repeating units.

[0233] 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.

[0234] The polymer surfactant can be synthesized by heating a monomer containing an unsaturated bond that provides the repeating units represented by formulas (6A) to (6E) and, if necessary, other repeating units, in an organic solvent with the addition of a radical initiator to polymerize the monomer. Examples of organic solvents used in polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of polymerization initiators include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization.

[0235] When synthesizing the polymer 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 number of moles of the monomers to be polymerized.

[0236] 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, per 80 parts by mass of the base polymer (B). When the surfactant (F) content is 0.1 part by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, while when the surfactant content 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 types.

[0237] [(G) Other ingredients] The chemically amplified resist composition of the present invention may contain, as other components (G), compounds that decompose in the presence of acid to generate acid (acid amplifier compounds), organic acid derivatives, fluorine-substituted alcohols, crosslinkers, compounds with Mw of 3,000 or less (dissolution inhibitors) whose solubility in a developer changes upon the action of acid, and acetylene alcohols. Examples of the acid amplifier compounds include those described in JP-A-2009-269953 and JP-A-2010-215608. When the acid amplifier compound is included, its content is preferably 0 to 5 parts by weight, more preferably 0 to 2 parts by weight, and even more preferably 0 to 1 part by weight, relative to 80 parts by weight of the (B) base polymer. If the content is too high, it may be difficult to control acid diffusion, resulting in degradation of resolution and pattern shape. Examples of the organic acid derivatives, fluorine-substituted alcohols, and dissolution inhibitors include those described in JP-A-2009-269953 and JP-A-2010-215608. The addition of an organic acid derivative or a dissolution inhibitor is optional, and, like the above-mentioned components, reference can be made to the compounds described in JP-A-2009-269953 or JP-A-2010-215608.

[0238] [Pattern formation method] The pattern forming method of the present invention includes the steps of forming a resist film on a substrate using the aforementioned chemically amplified resist composition, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer.

[0239] The substrate may be, for example, a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.).

[0240] 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 10 to 2,000 nm, and then pre-baking the composition on a hot plate preferably at 60 to 180°C for 10 to 600 seconds, more preferably at 70 to 150°C for 15 to 300 seconds.

[0241] When KrF excimer laser light, ArF excimer laser light, or EUV is used to expose the resist film, a mask for forming a desired pattern is used, and the exposure dose 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

[0242] In addition to the usual exposure method, the immersion method can also be used, in which a liquid with a refractive index of 1.0 or higher is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0243] The water-insoluble protective film is used to prevent elution from the resist film and increase the water sliding property of the film surface. It can be broadly divided into two types. One is an organic solvent-removable type that requires stripping before alkaline aqueous development using an organic solvent that does not dissolve the resist film. The other is an alkaline aqueous solution-soluble type that is soluble in alkaline developer and removes the protective film along with removing the soluble portion of the resist film. The latter is particularly based on a polymer containing 1,1,1,3,3,3-hexafluoro-2-propanol residues that is insoluble in water but soluble in alkaline developer, and is preferably dissolved in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof. Materials can also be prepared by dissolving the water-insoluble, alkaline developer-soluble surfactant described above in an alcohol solvent with 4 or more carbon atoms, an ether solvent with 8 to 12 carbon atoms, or a mixed solvent thereof.

[0244] After the exposure, a post-exposure bake (PEB) may be carried out as necessary. The PEB can be carried out, for example, by heating on a hot plate preferably at 60 to 150°C for 1 to 5 minutes, more preferably at 80 to 140°C for 1 to 3 minutes.

[0245] Development can be carried out using, for example, a developer such as an aqueous alkaline solution of preferably 0.1 to 5 mass %, more preferably 2 to 3 mass %, tetramethylammonium hydroxide (TMAH) or an organic solvent developer, for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, by a conventional method such as dipping, puddling, or spraying. By development, a desired pattern can be formed on the substrate.

[0246] A method for forming a positive pattern using an alkaline aqueous solution as a developer is described in detail in paragraphs

[0138] to

[0146] of JP-A No. 2011-231312, and a method for forming a negative pattern using an organic solvent as a developer is described in detail in paragraphs

[0173] to

[0183] of JP-A No. 2015-214634.

[0247] After the resist film is formed, a pure water rinse (post-soak) may be performed to extract the acid generator and the like from the surface of the resist film or to wash away particles, or a rinse (post-soak) may be performed to remove water remaining on the film after exposure.

[0248] Furthermore, as a technology to extend ArF lithography down to 32 nm, patterns can be formed using double patterning. Double patterning methods include the trench method, in which a 1:3 trench pattern is processed by a first exposure and etching, and then a 1:3 trench pattern is formed by a second exposure at a different position to form a 1:1 pattern, and the line method, in which a 1:3 isolated leave pattern is processed by a first exposure and etching, and then a 1:3 isolated leave pattern is formed under the first substrate by a second exposure at a different position to form a 1:1 pattern with half the pitch.

[0249] Furthermore, when forming a hole pattern by negative tone development using an organic solvent-containing developer, exposure is performed using dipole illumination with two line patterns in the X-axis and Y-axis directions, allowing the use of light with the highest contrast. Furthermore, adding s-polarized illumination to the dipole illumination with two line patterns in the X-axis and Y-axis directions can further increase contrast. These pattern formation methods are described in detail in JP 2011-221513 A.

[0250] With regard to the developer in the pattern formation method of the present invention, examples of the alkaline aqueous developer include the above-mentioned TMAH aqueous solution and the alkaline aqueous solution described in paragraphs

[0148] to

[0149] of JP2015-180748A, and a 2 to 3 mass % TMAH aqueous solution is preferred.

[0251] For organic solvent development, the following developers are available: 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 Examples of organic solvents that can be used include methyl lactate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate. These organic solvents may be used alone or in combination of two or more.

[0252] The developed hole or trench pattern can also be shrunk using techniques such as thermal flow, RELACS (Resolution Enhancement Lithography Assisted by Chemical Shrink), and DSA (Directed Self-Assembly). A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is 10 to 300 seconds. Finally, excess shrink agent is removed, and the hole pattern is shrunk.

[0253] By using a chemically amplified resist composition containing the onium salt compound represented by formula (1) of the present invention as a photoacid generator, it is possible to easily form a fine pattern that is excellent in lithography performance such as CDU, LWR, and sensitivity. [Example]

[0254] The present invention will be specifically explained below by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The apparatuses used are as follows. IR: Thermo Fisher Scientific, NICOLET 6700 · 1 H-NMR: ECA-500 manufactured by JEOL Ltd. · 19 F-NMR: ECA-500 manufactured by JEOL Ltd. MALDI TOF-MS: JEOL S3000

[0255] [1] Synthesis of photoacid generator [Example 1-1] Synthesis of PAG-1 (1) Synthesis of acid chloride 1 [ka]

[0256] Under a nitrogen atmosphere, 2,2,5-trimethyl-1,3-dioxane-5-carboxylic acid (17.4 g) and toluene (135 g) were placed in a flask, and oxalyl chloride (15.2 g) was added dropwise to the flask in a 40°C oil bath. After the dropwise addition, the reaction system was stirred at 40°C and aged for 16 hours. After aging, the solvent was distilled off to obtain oily acid chloride 1 (yield 19.3 g).

[0257] (2) Synthesis of intermediate 2 [ka]

[0258] Under a nitrogen atmosphere, 4-iodophenol (26.4 g), acid chloride 1 (19.3 g), and methylene chloride (300 g) were placed in a flask, and triethylamine (14.2 g), dimethylaminopyridine (1.2 g), and methylene chloride (30 g) were added dropwise to the flask under ice cooling. After the addition, the reaction mixture was warmed to room temperature and aged for 22 hours. After aging, the reaction mixture was ice-cooled, and 100 g of saturated aqueous sodium bicarbonate was added dropwise to terminate the reaction. A typical aqueous work-up was then performed, the solvent was distilled off, and diisopropyl ether (60 g) was added and stirred to wash the mixture. The solvent was removed, and the remaining solvent was distilled off to obtain oily intermediate 2 (yield: 28.7 g, 76.3%).

[0259] (3) Synthesis of diol A-1 [ka]

[0260] Under a nitrogen atmosphere, intermediate 2 (15.3 g), 3% by mass hydrochloric acid (50 g), and THF (50 g) were placed in a flask, stirred at room temperature, and aged for 19 hours. After aging, the solvent was distilled off, and methylene chloride (200 g) and water (40 g) were added for extraction. A typical aqueous work-up was then performed, the solvent was distilled off, and diisopropyl ether (150 g) was added and stirred. After stirring for 1.5 hours, the precipitated solid was filtered and dried under reduced pressure for 2 hours to obtain diol A-1 as a white solid (yield 9.5 g, 70.6%).

[0261] (4) Preparation of acid chloride 4 [ka]

[0262] Under a nitrogen atmosphere, intermediate 3 (20.9 g), dimethylformamide (0.2 g), and methylene chloride (100 g) were placed in a flask, and oxalyl chloride (4.9 g) was added dropwise at room temperature. After the addition, the mixture was aged for 16 hours. After aging, the solvent was distilled off to obtain oily acid chloride 4 (21.5 g).

[0263] (5) Synthesis of PAG-1 [ka]

[0264] Under a nitrogen atmosphere, acid chloride 4 (21.5 g), diol A-1 (4.2 g), and methylene chloride (85 g) were placed in a flask, and pyridine (2.4 g) was added dropwise to the flask under ice cooling. After the dropwise addition, the reaction system was warmed to room temperature and aged for 21 hours. After aging, the reaction system was ice-cooled, and 5% by mass hydrochloric acid (30 g) was added to terminate the reaction. The organic layer was then separated by a separation operation, subjected to standard aqueous work-up, and the solvent was distilled off. The resulting oily compound was a mixture of the target compound and the acid anhydride derived from acid chloride 4. Sodium bicarbonate (0.5 g), dimethylaminopyridine (0.1 g), THF (35 g), and water (15 g) were added to the mixture and hydrolyzed at room temperature. After stirring for 1 hour, methylene chloride (150 g) and water (35 g) were added and extracted. The mixture was then washed with 1% by weight hydrochloric acid, saturated sodium bicarbonate water, and subjected to standard aqueous work-up, after which the solvent was distilled off. Diisopropyl ether (70 g) was then added and stirred, and the precipitated solid was filtered to obtain solid PAG-1 (yield: 17.0 g, 86.2%). The IR spectrum data and TOF-MS results of PAG-1 are shown below. 1 H-NMR, 19 The results of F-NMR / DMSO-d6) are shown in Figures 1 and 2. IR(D-ATR): ν= 3498, 3064, 2939, 2862, 1759, 1634, 1581, 1478, 1448, 1372, 1323, 1251, 1217, 1186, 1167, 1111, 1074, 1029, 1007, 996, 941, 905, 879, 837, 802, 750, 684, 641, 577, 552, 502 cm -1 . TOF-MS (MALDI): POSITIVE M+ 263.1(C 18 H 15 S + equivalent) NEGATIVE M - 1329.0(C 51 H 48 F 10 IO 16 S3 - equivalent)

[0265] [Example 1-2] Synthesis of PAG-2 (1) Preparation of acid chloride 6 [ka]

[0266] Under a nitrogen atmosphere, intermediate 5 (29.0 g), dimethylformamide (0.2 g), and methylene chloride (150 g) were placed in a flask, and oxalyl chloride (6.9 g) was added dropwise at room temperature. After the addition, the mixture was aged for 16 hours. After aging, the solvent was distilled off to obtain oily acid chloride 6 (29.8 g).

[0267] (2) Synthesis of PAG-2 [ka]

[0268] Under a nitrogen atmosphere, acid chloride 6 (29.8 g), diol A-1 (5.8 g), and methylene chloride (80 g) were placed in a flask, and pyridine (3.3 g) was added dropwise thereto under ice cooling. After the dropwise addition, the reaction system was warmed to room temperature and aged for 24 hours. After aging, the reaction system was ice-cooled, and 5% by mass hydrochloric acid (30 g) was added to quench the reaction. Thereafter, the organic layer was separated by a separation operation, and subjected to a conventional aqueous work-up, followed by distillation of the solvent. The resulting oily compound was a mixture of the target compound and the acid anhydride derived from acid chloride 6. Sodium bicarbonate (0.8 g), dimethylaminopyridine (0.1 g), THF (50 g), and water (30 g) were added to the mixture and hydrolyzed at room temperature. After stirring for 1 hour, methylene chloride (100 g) and water (30 g) were added and extracted. The mixture was then washed with 1% by weight hydrochloric acid, saturated sodium bicarbonate water, and subjected to standard aqueous work-up, after which the solvent was distilled off. Hexane (200 g) was then added and stirred, and the precipitated solid was filtered off to obtain solid PAG-2 (yield: 22.5 g, 82.0%). The IR spectrum data and TOF-MS results of PAG-2 are shown below. 1 H-NMR, 19 The results of F-NMR / DMSO-d6) are shown in Figures 3 and 4. IR(D-ATR): ν= 3481, 3091, 2939, 2861, 1758, 1737, 1578, 1481, 1449, 1373, 1320, 1247, 1186, 1167, 1111, 1074, 1028, 994, 941, 904, 879, 837, 759, 707, 681, 641, 613, 576, 552, 525, 490, 423 cm -1 . TOF-MS (MALDI): POSITIVE M + 261.0(C 18 H 13 S + equivalent) NEGATIVE M - 1327.7(C 51 H 46 F 10 IO 16 S3 - equivalent)

[0269] [Example 1-3] Synthesis of PAG-3 (1) Preparation of acid chloride 8 [ka]

[0270] Under a nitrogen atmosphere, intermediate 7 (17.9 g), dimethylformamide (0.2 g), and methylene chloride (80 g) were placed in a flask, and oxalyl chloride (4.2 g) was added dropwise at room temperature. After the addition, the mixture was aged for 17 hours. After aging, the solvent was distilled off to obtain oily acid chloride 8 (19.6 g).

[0271] (2) Synthesis of PAG-3 [ka]

[0272] Under a nitrogen atmosphere, acid chloride 8 (19.6 g), diol A-1 (3.5 g), and methylene chloride (80 g) were placed in a flask, and pyridine (2.0 g) was added dropwise to the flask under ice cooling. After the dropwise addition, the reaction system was warmed to room temperature and aged for 21 hours. After aging, the reaction system was ice-cooled, and 5% by mass hydrochloric acid (30 g) was added to terminate the reaction. The organic layer was then separated by a separation operation, subjected to standard aqueous work-up, and the solvent was distilled off. The resulting oily compound was a mixture of the target compound and the acid anhydride derived from acid chloride 8. Sodium bicarbonate (0.5 g), dimethylaminopyridine (0.1 g), THF (35 g), and water (15 g) were added to the mixture, and hydrolysis was carried out at room temperature. After stirring for 1 hour, methylene chloride (100 g) and water (30 g) were added and extracted. The mixture was then washed with 1% by weight hydrochloric acid, saturated sodium bicarbonate water, and subjected to standard aqueous work-up. The solvent was then distilled off to obtain oily PAG-3 (yield: 16.2 g, 91.1%). The IR spectrum data and TOF-MS results of PAG-3 are shown below. 1 H-NMR, 19 The results of F-NMR / DMSO-d6) are shown in Figures 5 and 6. IR(D-ATR): ν= 3484, 3102, 3061, 2971, 2939, 2865, 1759, 1587, 1492, 1453, 1407, 1370, 1325, 1243, 1188, 1164, 1111, 1075, 1031, 1008, 993, 942, 903, 880, 839, 642, 577, 553, 520, 438 cm -1 . TOF-MS (MALDI): POSITIVE M + 317.1(C 18 H 12 F3S + equivalent) NEGATIVE M - 1383.7(C 51 H 45 F 13 IO 16 S3 - equivalent)

[0273] [Examples 1-4] Synthesis of PAG-4 (1) Synthesis of acid chloride 9 [ka]

[0274] Under a nitrogen atmosphere, triiodobenzoic acid (50.0 g), dimethylformamide (0.4 g), and chloroform (340 g) were placed in a flask and stirred at 55°C. Thionyl chloride (23.8 g) was added dropwise to the resulting mixed solution. After the dropwise addition, the reaction system was aged in an oil bath at 55°C for 20 hours. After aging, the solvent and excess thionyl chloride were distilled off to obtain solid acid chloride 9.

[0275] (2) Synthesis of intermediate 11 [ka]

[0276] Under a nitrogen atmosphere, alcohol 10 (14.5 g), triethylamine (11.8 g), dimethylaminopyridine (1.0 g), and methylene chloride (300 g) were placed in a flask, and acid chloride 9 was added in small portions under ice cooling. After the addition, the reaction mixture was warmed to room temperature and aged for 20 hours. After aging, the reaction mixture was ice-cooled, and 50 g of saturated aqueous sodium bicarbonate was added dropwise to quench the reaction. The organic layer was then separated by a liquid separation operation, subjected to a standard aqueous work-up, the solvent was evaporated, and diisopropyl ether (200 g) was added and stirred. After stirring for 2 hours, the precipitated solid was filtered and dried under reduced pressure for 2 hours to obtain intermediate 11 as a white solid (yield: 29.4 g, 54.0%).

[0277] (3) Synthesis of diol A-2 [ka]

[0278] Under a nitrogen atmosphere, Intermediate 11 (13.1 g), 2.5% by mass hydrochloric acid (30 g), and THF (30 g) were placed in a flask and aged at room temperature for 16 hours. After aging, the solvent was distilled off, and methylene chloride (80 g) and water (30 g) were added for extraction. A typical aqueous work-up was then performed, the solvent was distilled off, and diisopropyl ether (60 g) was added and stirred. After stirring for 2 hours, the precipitated solid was filtered and dried under reduced pressure for 2 hours to obtain Diol A-2 as a white solid (yield 7.2 g, 58.6%).

[0279] (4) Synthesis of PAG-4 [ka]

[0280] Under a nitrogen atmosphere, acid chloride 4 (20.2 g), diol A-2 (7.2 g), and methylene chloride (80 g) were placed in a flask, and pyridine (2.2 g) was added dropwise to the mixture under ice cooling. After the dropwise addition, the reaction mixture was warmed to room temperature and aged for 22 hours. After aging, the reaction mixture was ice-cooled, and 5% by mass hydrochloric acid (30 g) was added to quench the reaction. The organic layer was then separated and subjected to standard aqueous work-up, followed by distillation of the solvent. The resulting oily compound was a mixture of the target compound and the acid anhydride derived from acid chloride 4. Sodium bicarbonate (0.5 g), dimethylaminopyridine (0.1 g), THF (35 g), and water (15 g) were added to the mixture, and hydrolysis was carried out at room temperature. After stirring for 1 hour, methylene chloride (100 g) and water (15 g) were added and extracted. The mixture was then washed with 1% by weight hydrochloric acid, saturated sodium bicarbonate water, and subjected to standard aqueous work-up. The solvent was then distilled off to obtain oily PAG-4 (yield: 27.8 g, 100%). The IR spectrum data and TOF-MS results of PAG-4 are shown below. 1 H-NMR, 19 The results of F-NMR / DMSO-d6) are shown in Figures 7 and 8. IR(D-ATR): ν= 3492, 3063, 2937, 2861, 1761, 1733, 1582, 1521, 1477, 1448, 1369, 1323, 1266, 1251, 1217, 1184, 1111, 1074, 1024, 996, 942, 912, 877, 837, 750, 685, 642, 578, 552, 503 cm -1 . TOF-MS (MALDI): POSITIVE M + 263.1(C 18 H 15 S + equivalent) NEGATIVE M - 1609.5, 383.2(C 53 H 50 F 10 I3O 16 S3 - equivalent)

[0281] [Examples 1-5] Synthesis of PAG-5 [ka]

[0282] Under a nitrogen atmosphere, acid chloride 8 (13.8 g), diol A-2 (4.6 g), and methylene chloride (50 g) were placed in a flask, and pyridine (1.4 g) was added dropwise to the flask under ice cooling. After the dropwise addition, the reaction system was warmed to room temperature and aged for 22 hours. After aging, the reaction system was ice-cooled, and 5% by mass hydrochloric acid (30 g) was added to terminate the reaction. The organic layer was then separated by a separation operation, subjected to standard aqueous work-up, and the solvent was distilled off. The resulting oily compound was a mixture of the target compound and the acid anhydride derived from acid chloride 8. Sodium bicarbonate (0.5 g), dimethylaminopyridine (0.1 g), THF (35 g), and water (15 g) were added and hydrolyzed at room temperature. After stirring for 1 hour, methylene chloride (100 g) and water (15 g) were added and extracted. The resulting mixture was then washed with 1% by weight hydrochloric acid, saturated sodium bicarbonate water, and subjected to standard aqueous work-up. The solvent was then distilled off to obtain oily PAG-5 (yield: 14.2 g, 96.8%). The IR spectrum data and TOF-MS results of PAG-5 are shown below. 1 H-NMR, 19 The results of F-NMR / DMSO-d6) are shown in Figures 9 and 10. IR(D-ATR): ν= 3493, 3102, 3059, 2958, 2871, 1761, 1734, 1712, 1587, 1521, 1492, 1468, 1406, 1368, 1323, 1244, 1185, 1171, 1112, 1074, 1027, 1008, 992, 878, 840, 704, 642, 578, 553, 521, 438 cm -1 . TOF-MS (MALDI): POSITIVE M + 317.1(C18 H 12 F3S + equivalent) NEGATIVE M - 1663.4(C 53 H 47 F 13 I3O 16 S3 - equivalent)

[0283] [Examples 1-6 to 1-11] Synthesis of PAG-6 to PAG-11 The following bis-sulfonate salts were obtained using the corresponding raw materials in the same manner as in the above-mentioned examples, with reference to the synthesis methods described above. The anion and cation raw materials used were either commercially available products or those synthesized by known methods. [ka]

[0284] [ka]

[0285] [2] Synthesis of base polymer [Synthesis Example 1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, 22 g of 1-tert-butylcyclopentyl methacrylate, 17 g of 2-oxotetrahydrofuran-3-yl methacrylate, 0.48 g of V-601 (Fujifilm Wako Pure Chemical Industries, Ltd.), 0.41 g of 2-mercaptoethanol, and 50 g of methyl ethyl ketone were added to prepare a monomer-polymerization initiator solution. 23 g of methyl ethyl ketone was added to a separate flask under a nitrogen atmosphere and heated to 80°C with stirring. The monomer-polymerization initiator solution was then added dropwise over 4 hours. After the addition, the polymerization solution was stirred for 2 hours while maintaining the temperature at 80°C, and then cooled to room temperature. The resulting polymerization solution was added dropwise to 640 g of vigorously stirred methanol, and the precipitated polymer was filtered off. The polymer was washed twice with 240 g of methanol and then vacuum-dried at 50°C for 20 hours to obtain polymer P-1 as a white powder (yield: 36 g, 90%). The Mw of polymer P-1 was 8,200, and the Mw / Mn was 1.63. [ka]

[0286] [Synthesis Examples 2 to 4] Synthesis of polymers P-2 to P-4 The following polymers P-2 to P-4 were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of the respective monomers were changed. [ka]

[0287] [3] Preparation of chemically amplified resist composition [Examples 2-1 to 2-17, Comparative Examples 1-1 to 1-12] The photoacid generators synthesized in Examples 1-1 to 1-11, base polymers, photoacid generators other than those synthesized in Examples 1-1 to 1-11 (PAG-W, PAG-X, PAG-Y, PAG-Z), quenchers (Q-1, Q-2), and alkali-soluble surfactant (SF-1) were dissolved in a solvent containing 0.01% by mass of surfactant A (manufactured by Omnova), and the resulting solution was filtered through a 0.2 μm Teflon filter to prepare chemically amplified resist compositions. The compositions of each chemically amplified resist composition prepared are shown in Tables 1 and 2 below.

[0288] [Table 1]

[0289] [Table 2]

[0290] In Tables 1 and 2, the solvents, quenchers (Q-1, Q-2), alkali-soluble surfactant (SF-1), other photoacid generators (PAG-W, PAG-X, PAG-Y, PAG-Z), and surfactant A are as follows: Solvent: PGMEA (propylene glycol monomethyl ether acetate) GBL (γ-butyrolactone)

[0291] Quencher: Q-1, Q-2 [ka]

[0292] Other photoacid generators: PAG-W, PAG-X, PAG-Y, PAG-Z [ka]

[0293] Alkali-soluble surfactant SF-1: Poly(2,2,3,3,4,4,4-heptafluoro-1-isobutyl-1-butyl methacrylate)-9-(2,2,2-trifluoro-1-trifluoromethylethyloxycarbonyl)-4-oxatricyclo[4.2.1.0] methacrylate 3,7 ]nonan-5-on-2-yl) Mw=7,700 Mw / Mn=1.82 [ka]

[0294] 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=1,500

[0295] [4] Evaluation of Chemically Amplified Resist Compositions: ArF Lithography Evaluation (1) [Examples 3-1 to 3-4, Comparative Examples 2-1 to 2-4] A silicon substrate was coated with an antireflective coating solution (ARC-29A, manufactured by Nissan Chemical Co., Ltd.) and baked at 200°C for 60 seconds to produce a 100-nm-thick antireflective coating. Each resist composition (R-01 to R-04, R-18 to R-21) was spin-coated onto the antireflective coating and baked at 90°C for 60 seconds using a hot plate to produce a 90-nm-thick resist film. This was then subjected to immersion exposure using an ArF excimer laser scanner (Nikon Corporation, NSR-S610C, NA 1.30, quadrupole, 6% halftone phase shift mask). Water was used as the immersion fluid. The substrate was then baked (PEB) for 60 seconds at the temperature listed in Table 3 and developed for 60 seconds in a 2.38% by weight TMAH aqueous solution to form a line-and-space (LS) pattern. The formed LS pattern was observed with a critical dimension SEM (CG5000) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, LWR, and MEF were evaluated according to the following methods. The results are shown in Table 3.

[0296] [Sensitivity evaluation] For a 40 nm 1:1 line and space pattern, the optimal exposure dose (Eop, mJ / cm) is the exposure dose that results in a line width dimension of 40 nm. 2 ) was calculated as the sensitivity. The smaller this value, the higher the sensitivity.

[0297] [LWR rating] For the LS pattern obtained by irradiation at Eop, the dimensions were measured at 30 points along the longitudinal direction of the line, and from the results, three times the standard deviation (σ) (3σ) was calculated, which was taken as the LWR. The smaller the LWR value, the less fluctuation there is in the line pattern, and the better it is.

[0298] [MEF Rating] For the dimensions on the wafer at Eop, a mask was used with a fixed pitch (80 nm) and only the line width varied (38 to 42 nm, in 1 nm increments), and exposure was performed, and the dimensions after wafer transfer were measured. For line width, the dimensions of the transferred pattern were plotted against the mask design dimensions, and the slope was calculated using linear approximation, which was taken as the MEF. The smaller the MEF value, the better, as it can reduce the impact of mask pattern finishing errors.

[0299] [Table 3]

[0300] The results shown in Table 3 demonstrate that the chemically amplified resist composition of the present invention has excellent LWR and MEF and is suitable as a material for ArF immersion lithography that involves alkaline development.

[0301] [5] Evaluation of Chemically Amplified Resist Compositions: ArF Lithography Evaluation (2) [Examples 4-1 to 4-4, Comparative Examples 3-1 to 3-4] Each resist composition (R-01 to R-04, R-18 to R-21) was spin-coated onto a silicon wafer substrate for a trilayer process. The substrate was a 200 nm thick spin-on carbon film (ODL-50, manufactured by Shin-Etsu Chemical Co., Ltd.) (carbon content: 80% by weight) coated with a 35 nm thick silicon-containing spin-on hard mask (SHB-A940, silicon content: 43% by weight). The resist was then baked at 100°C for 60 seconds using a hotplate to produce a 90 nm thick resist film. This resist film was then subjected to immersion exposure through a mask using an ArF excimer laser immersion scanner (Nikon Corporation, NSR-610C, NA: 1.30, σ: 0.98 / 0.74, cross-pole aperture: 35°) while varying the exposure dose and focus. Water was used as the immersion fluid. After exposure, the resist was subjected to PEB for 60 seconds at the temperature listed in Table 4, followed by development for 30 seconds using butyl acetate as the developer. The mask was a binary mask with a design of 55 nm dots / 90 nm pitch (actual dimensions on the mask were 4 times larger due to 1 / 4 reduction projection exposure), and the hole pattern of the reverse pattern formed on the resist film was observed with a Hitachi High-Tech TD-SEM (S-9380), and the sensitivity, CDU, and MEF were evaluated according to the following methods. The results are shown in Table 4.

[0302] [Sensitivity evaluation] The optimal exposure dose (Eop, mJ / cm) for achieving a hole inner diameter of 50 nm is 2) was calculated as the sensitivity. The smaller this value, the higher the sensitivity.

[0303] [CDU Rating] The dimensions of 50 hole patterns obtained by irradiation at Eop were measured, and the three-fold value (3σ) of the standard deviation (σ) was calculated from the results, and this was taken as CDU. The smaller the CDU, the better the result.

[0304] [MEF Rating] For the dimensions on the wafer at Eop, a mask was used in which the pitch was fixed but only the dot size was changed, and exposure was performed to measure the hole dimensions after wafer transfer. For the hole dimensions, the dimensions of the transferred pattern were plotted against the mask design dimensions, and the slope was calculated using linear approximation, which was taken as the MEF. The smaller the MEF value, the better, as it can reduce the impact of mask pattern finishing errors.

[0305] [Table 4]

[0306] The results shown in Table 4 demonstrate that the chemically amplified resist composition of the present invention has excellent CDU and MEF properties and is suitable as a material for ArF immersion lithography that uses organic solvent development.

[0307] [6] Evaluation of chemically amplified resist compositions: EUV lithography evaluation [Examples 5-1 to 5-13, Comparative Examples 4-1 to 4-8] Each resist composition (R-05 to R-17, R-22 to R-29) was spin-coated onto a silicon substrate coated with a 20 nm thick silicon-containing spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) (43% silicon by weight) and pre-baked at 105°C for 60 seconds on a hot plate to produce a 50 nm thick resist film. This was then exposed using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, 46 nm pitch on the wafer, +20% bias hole pattern mask), subjected to PEB on a hot plate at 85°C for 60 seconds, and developed for 30 seconds in a 2.38% by weight TMAH aqueous solution to produce a 23 nm hole pattern. The hole pattern after development was observed with a critical dimension SEM (CG5000) manufactured by Hitachi High-Technologies Corporation, and the sensitivity and CDU were evaluated according to the following methods. The results are shown in Table 5.

[0308] [Sensitivity evaluation] The optimal exposure dose (Eop, mJ / cm) when forming a hole dimension of 23 nm is 2 ) was calculated as the sensitivity. The smaller this value, the higher the sensitivity.

[0309] [CDU Rating] For hole patterns obtained by irradiation at Eop, the dimensions were measured at 50 points within the same exposure shot, and the three times value (3σ) of the standard deviation (σ) was calculated from the results and used as CDU. The smaller this value, the better the dimensional uniformity of the hole pattern.

[0310] [Table 5]

[0311] The results shown in Table 5 demonstrate that the chemically amplified resist composition of the present invention has excellent sensitivity and CDU, and is suitable as a material for EUV lithography.

Claims

1. A photoacid generator which is an onium salt compound represented by the following formula (1a), which is composed of an anion containing an aromatic group substituted with an iodine atom and two sulfonate groups, and a sulfonium cation or an iodonium cation: 【Chemical 1】 (In the formula, R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. 1 and R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached, and R 3 and R 4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R f1 , R f2 , R f3 and R f4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and R f1 and R f2 At least one of R is a fluorine atom or a trifluoromethyl group; f3 and R f4 At least one of the groups is a fluorine atom or a trifluoromethyl group. m 1 and m 2 are each independently an integer of 1 to 4. n 1 and n 2 are each independently an integer of 0 to 4. L a1 and L a2 are each independently an ether bond, an ester bond, a sulfonate ester bond or a carbonate bond. L c1 ' and L c2 Each of the ' is independently a cyclic hydrocarbylene group having 3 to 10 carbon atoms. L b1 ' and L b2 Each of the ' is independently an ether bond, an ester bond, a sulfonate ester bond, or a carbamate bond which is a carbonate bond. L b3 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. A 1 , A 2 and A 3 are each independently a single bond or a hydrocarbylene group having 1 to 8 carbon atoms which may contain a heteroatom, and —CH 2 A portion of - may be substituted with -O- or -C(=O)-. A 4 represents a hydrogen atom, a hydroxy group, or a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, and —CH 2 A portion of - may be substituted with -O- or -C(=O)-. Ar is a (p+1)-valent aromatic group having 3 to 15 carbon atoms, and a hydrogen atom in the aromatic group may be substituted with a fluorine atom, a hydroxy group, or a hydrocarbyl group having 1 to 15 carbon atoms. In addition, a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and —CH 2 A part of - is -O-, -C(=O)- or -N(R N )- may be substituted. N is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, in which a hydrogen atom may be substituted with a group containing a hetero atom, and —CH 2 A part of - is -O-, -C(=O)- or -S(=O) 2 It may be substituted with -. p is an integer satisfying the condition 1≦p≦5. Za + and Zb + are each independently a sulfonium cation or an iodonium cation.

2. L c1 ' and L c2 2. The photoacid generator according to claim 1, wherein ' is a cyclopentane-1,3-diyl group, a cyclohexane-1,2-diyl group, a cyclohexane-1,3-diyl group, a cyclohexane-1,4-diyl group, or a 1,2-phenylene group.

3. L b1 ' and L b2 3. The photoacid generator according to claim 1, wherein ' is an ester bond.

4. 4. The photoacid generator according to claim 1, wherein the onium salt compound is represented by the following formula (1b): 【Chemistry 2】 (In the formula, A 1 , A 2 , A 3 , A 4 , L b1 ', L b2 ', L b3 , Za + and Zb + is the same as above. p and q are integers satisfying the conditions 1≦p≦5, 0≦q≦4, and 1≦q+p≦5. R f5 and R f6 are each independently a hydrogen atom or a trifluoromethyl group. L a1 ' and L a2 Each of the ' is independently an ether bond or an ester bond. R 5 is a hydroxy group, a fluorine atom, or a hydrocarbyl group having 1 to 15 carbon atoms, in which a hydrogen atom may be substituted with a group containing a hetero atom, and —CH 2 A part of - is -O-, -C(=O)- or -N(R N )- may be substituted. N is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, in which a hydrogen atom may be substituted with a group containing a hetero atom, and —CH 2 A part of - is -O-, -C(=O)- or -S(=O) 2 When q is 2 or more, a plurality of R 5 may be the same or different, and two R 5 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are attached.

5. 5. The photoacid generator according to claim 4, wherein the onium salt compound is represented by the following formula (1c): 【Chemistry 3】 (In the formula, A 3 , L a1 ', L a2 ', L b3 , R 5 , R f5 , R f6 , p, q, Za + and Zb + is the same as above. L b4 and L b5 are each independently an ether bond or an ester bond. A 5 and A 6 are each independently a linear hydrocarbylene group having 1 to 4 carbon atoms. A 7 is a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 8 carbon atoms. Ring W 1 and Ring W 2 are each independently an alicyclic hydrocarbon group having 3 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms, which may contain a heteroatom.

6. Za + and Zb + and each independently represent a cation represented by the following formula (Z-1) or (Z-2): 【Chemistry 4】 (In the formula, R Z1 , R Z2 and R Z3 are each independently a halogen atom, a hydroxy group, or a hydrocarbyl group having 1 to 15 carbon atoms, a hydrogen atom in the hydrocarbyl group may be substituted with a group containing a hetero atom, and —CH 2 Part of - is -O-, -C(=O)-, -S-, -S(=O)-, -S(=O) 2 -or-N(R N )- may be substituted. L is a single bond, —CH 2 -, -O-, -C(=O)-, -S-, -S(=O)-, -S(=O) 2 -or-N(R N )-. R N is a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms, in which a hydrogen atom may be substituted with a group containing a hetero atom, and —CH 2 A part of - is -O-, -C(=O)- or -S(=O) 2 It may be substituted with -. x, y, and z each independently represent an integer of 0 to 5. When x is 2 or more, each R Z1 may be the same or different, and two R Z1 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. Z2 may be the same or different, and two R Z2 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are bonded. Z3 may be the same or different, and two R Z3 may be bonded to each other to form a ring together with the carbon atoms on the benzene ring to which they are attached.

7. 7. The photoacid generator according to claim 1, wherein p is an integer satisfying 1≦p≦3.

8. 8. A chemically amplified resist composition comprising: (A) the photoacid generator according to any one of claims 1 to 7; (B) a base polymer whose solubility in a developer changes under the action of an acid; and (C) an organic solvent.

9. 9. The chemically amplified resist composition according to claim 8, wherein the base polymer contains a repeating unit represented by the following formula (a) or a repeating unit represented by the following formula (b): 【Chemistry 5】 (In the formula, R A are each independently a hydrogen atom or a methyl group. Y 1 is a linking group having 1 to 12 carbon atoms and containing at least one selected from a single bond, a phenylene group, a naphthylene group, an ester bond, and a lactone ring. Y 2 is a single bond or an ester bond. Y 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 is a halogen atom, a hydroxy group, a cyano group, or a hydrocarbyl group having 1 to 6 carbon atoms, and —CH 2 A portion of - may be substituted with -O- or -C(=O)-. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and —CH 2 A part of the - may be substituted with an ether bond or an ester bond. a is 1 or 2, and b is an integer from 0 to 4, provided that 1≦a+b≦5.

10. 10. The chemically amplified resist composition according to claim 9, wherein the base polymer further contains a repeating unit represented by any one of the following formulas (g1) to (g3): 【Chemistry 6】 (In the formula, R A are each independently a hydrogen atom or a methyl group. Z 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z 11 -, -C(=O)-O-Z 11 - or -C(=O)-NH-Z 11 - is. Z 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z 2 is a single bond or an ester bond. Z 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -O-C(=O)-. Z 31 represents an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, a bromine atom, or an iodine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O-Z 51 -, -C(=O)-O-Z 51 - or -C(=O)-NH-Z 51 - is. Z 51 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, a halogen atom, or a hydroxy group. R 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. M - is a non-nucleophilic counterion.)

11. The chemically amplified resist composition according to any one of claims 8 to 10, further comprising a quencher.

12. The chemically amplified resist composition according to any one of claims 8 to 11, further comprising a photoacid generator other than the photoacid generator according to any one of claims 1 to 7.

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

14. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to any one of claims 8 to 13; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

15. 15. The pattern formation method according to claim 14, wherein the exposure is carried out by immersion exposure using a liquid with a refractive index of 1.0 or more interposed between the resist film and a projection lens.

16. 16. The pattern forming method according to claim 15, further comprising coating a protective film on the resist film, and performing immersion exposure by placing the liquid between the protective film and a projection lens.

17. 17. The pattern forming method according to claim 14, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light.

18. 18. The pattern forming method according to claim 17, wherein an aqueous alkaline solution is used as a developer to dissolve exposed areas and to obtain a positive pattern in which unexposed areas do not dissolve.

19. 18. The pattern forming method according to claim 17, wherein an organic solvent is used as a developer to dissolve the unexposed areas, thereby obtaining a negative pattern in which the exposed areas do not dissolve.

20. The developer may be 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, methyl propionate, ethyl propionate, or 20. The pattern formation method according to claim 19, wherein the lactone compound is at least one selected from the group consisting of methyl lactate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate.

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