Resist composition and pattern forming method

Abstract

To provide a resist composition containing a compound having excellent lithography performance, particularly acid diffusion control performance which greatly contributes to the improvement of LWR and CDU in high energy ray lithography, and a pattern-forming method using the resist composition.SOLUTION: A resist composition includes: (A) a compound represented by the following formula (1); (B) an organic solvent; and (C) a base polymer containing a repeating unit having an acid-unstable group. In the formula, M is a sulfur atom, or a selenium atom.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resist composition and a pattern forming method. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming finer at a rapid pace. In particular, the expansion of the flash memory market and the increase in memory capacity are driving miniaturization. The most advanced miniaturization technology is mass production of 65-nm node devices using ArF lithography, and preparations are underway for mass production of the next-generation 45-nm node using ArF immersion lithography. As for the next-generation 32-nm node, immersion lithography using ultra-high NA lenses that combine a liquid with a higher refractive index than water, a high-refractive index lens, and a high-refractive index resist material, extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, and double exposure (double patterning lithography) of ArF lithography are candidates that are being considered and are being considered.

[0003] However, with the rapid trend toward finer patterns, it is becoming difficult to form desired patterns using conventional resist compositions. As the pattern dimensions approach the diffusion length of the acid, acid diffusion has a significant effect on pattern formation after exposure, resulting in deterioration of contrast, fluctuation in pattern line width (line width roughness, LWR), and deterioration of pattern dimensional uniformity (CDU).

[0004] In order to solve the above problems, various studies have been made not only on base polymers and photoacid generators, but also on acid diffusion control agents, which are additives. Amines have been mainly used as acid diffusion control agents, but they are still insufficient in terms of improving LWR, which is an index of pattern roughness, and there are many issues to be improved. Studies using weak acid onium salts as acid diffusion control agents have also been reported. For example, Patent Document 1 describes a positive-type photosensitive composition for ArF excimer laser exposure containing a carboxylic acid onium salt. These suppress the acid decomposition reaction of acid labile groups and reduce (control) the acid diffusion distance by replacing a strong acid (sulfonic acid) generated from another photoacid generator by exposure with a weak acid onium salt, thereby replacing a strong acid (α,α-difluorosulfonic acid) with a weak acid (alkanesulfonic acid, carboxylic acid, etc.), and apparently function as a quencher, thereby becoming an acid diffusion control agent. Such onium salt-type acid diffusion control agents have been successful in improving LWR and CDU to a certain extent, but they are still not satisfactory for finer patterns with narrower pitches, and there is a demand for proposals of even better materials. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4226803 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist composition containing a compound having an acid diffusion control ability that greatly contributes to excellent lithography performance in high-energy beam lithography, in particular improvement of LWR and CDU, and a pattern formation method using the resist composition. [Means for solving the problem]

[0007] Means for Solving the Problem The present inventors have conducted intensive research in order to achieve the above-mentioned object and have discovered that a resist film obtained from a resist composition containing a sulfurane or selenurane compound having a specific structure has excellent lithography performance such as LWR and CDU, and is extremely effective for precise microfabrication, which has led to the completion of the present invention.

[0008] That is, the present invention provides the following resist composition and pattern forming method. 1. A resist composition comprising: (A) a compound represented by the following formula (1), (B) an organic solvent, and (C) a base polymer containing a repeating unit having an acid labile group: [ka] (In the formula, R 1 ~R 4 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 and L 1 and M may form a ring, R 1 and R 2 and R 3 and R 4 and may be bonded to each other to form a spiro ring in which M is a spiro atom. L 1 and L 2 are each independently -O- or -N(R)-, where R is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. M is a sulfur atom or a selenium atom. 2. The resist composition of 1, wherein the repeating unit having an acid labile group is represented by the following formula (a1) or (a2): [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 - and X 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. X 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. AL 1 and A.L. 2 are each independently an acid labile group. R 11 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. a is an integer from 0 to 4. 3. The resist composition of 1 or 2, wherein the base polymer further contains a repeating unit represented by the following formula (b1) or (b2): [ka] (In the formula, R A is the same as above. Y 1 is a hydrogen atom, or a polar group containing at least one selected from a hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride. m is 1 or 2. 4. The resist composition of any one of 1 to 3, wherein the base polymer further contains a repeating unit having a photoacid generating group. 5. The resist composition according to any one of 1 to 4, further comprising (D) a photoacid generator. 6. The resist composition according to any one of 1 to 5, further comprising (E) an acid diffusion controller other than the compound represented by formula (1). 7. The resist composition according to any one of 1 to 6, further comprising (F) a surfactant. 8. A pattern forming method comprising the steps of forming a resist film on a substrate using a resist composition according to any one of 1 to 7, exposing the resist film to KrF excimer laser light, ArF excimer laser light, an electron beam (EB) or EUV, and developing the exposed resist film using a developer. Effect of the Invention

[0009] The compound represented by formula (1) contained in the resist composition of the present invention functions well as an acid diffusion controller (quencher), making it possible to construct a pattern profile that is excellent in LWR and CDU and also has high resolution. [Brief description of the drawings]

[0010] [Figure 1] 1 is a 1H-NMR spectrum of compound QA obtained in Synthesis Example 1-1. [Diagram 2] 1 is a 19F-NMR spectrum of compound QA obtained in Synthesis Example 1-1. [Diagram 3] 1 is a 1H-NMR spectrum of compound QB obtained in Synthesis Example 1-2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The resist composition of the present invention is characterized by comprising a compound represented by the following formula (1): [ka]

[0012] In formula (1), R 1 ~R 4 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 and L 1 and M may form a ring, R 1 and R 2 and R 3 and R 4and may be bonded to each other to form a spiro ring with M as the spiro atom. 1 and L 2 are each independently -O- or -N(R)-. R is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. M is a sulfur atom or a selenium atom.

[0013] R 1 ~R 4 The hydrocarbyl group having 1 to 20 carbon atoms, represented by R, may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups 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 such as decanyl group, adamantyl group, adamantylmethyl group, etc.; aryl groups such as phenyl group, naphthyl group, anthracenyl group, etc. In addition, some of the hydrogen atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, halogen atoms other than fluorine atoms, etc., and groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, etc. may be interposed between the carbon atoms of these groups, and as a result, hydroxyl groups, cyano groups, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, etc. may be included.

[0014] Specific examples of the compound represented by formula (1) include, but are not limited to, those shown below. [ka]

[0015] The compound represented by formula (1) can be synthesized by combining known organic chemistry techniques, for example, by referring to Journal of the Chemical Society [Section] D: Chemical Communications, 1971), (12), p649-50, Journal of Organic Chemistry, Vol. 42, No. 25, 1977, p4006-4016, Journal of Organic Chemistry, Vol. 46, No. 6, 1981, p1049-1053, etc.

[0016] The compound represented by formula (1) functions extremely effectively as an acid diffusion controller when applied to a resist composition. In the present invention, the acid diffusion controller is a material for trapping the acid generated by the photoacid generator in the resist composition to prevent the acid from diffusing to the unexposed area, thereby forming a desired pattern.

[0017] Although the mechanism by which the compound represented by formula (1) controls acid diffusion is unclear, one possibility is as follows. The compound reacts with the acid generated by the photoacid generator to control the ML 1 or ML 2 It is speculated that one of the bonds is broken and converted to a sulfonium cation or a selenium cation. In this case, the counter anion becomes a conjugate base of the generated acid, that is, the generated acid is trapped. As a result, the compound represented by formula (1) functions as an acid diffusion control agent.

[0018] Amine compounds have long been used as acid diffusion control agents for photoresist compositions. Amine compounds neutralize and capture the acid generated by photoacid generators. However, amine compounds cause uneven distribution within the resist film and volatilization from the surface of the resist film (chemical flare), resulting in dark (area with a wide light-shielded area) and bright (area with a wide exposed area) dimensional differences, and also cause shape defects such as surface insolubility. It is possible to prevent volatilization by designing the compound to have a large molecular weight and raising the boiling point, but the issues of uneven distribution within the film and surface insolubility remain.

[0019] On the other hand, the compound represented by formula (1) is a sulfurane or selenurane compound that is highly crystalline and non-volatile, so there is no concern about chemical flare. Furthermore, the compound represented by formula (1) has low polarity and is highly compatible with the resist casting solvent (e.g., propylene glycol monomethyl ether acetate), so it is presumed to be uniformly dispersed within the film. Therefore, it is thought that the generated acid is uniformly trapped in the exposed area, improving LWR and CDU.

[0020] An example of an acid diffusion control agent other than an amine compound is an onium salt type acid diffusion control agent. An onium salt type acid diffusion control agent is a salt compound of a weak acid (here, the weak acid is, for example, a carboxylic acid or an alkane sulfonic acid), and traps the generated acid by causing ion exchange with a strong acid (for example, α,α'-difluorosulfonic acid) generated by a photoacid generator. The weak acid generated instead cannot cleave the acid labile group of the base polymer in the photoresist composition. Therefore, an onium salt of a weak acid functions as an acid diffusion control agent. Specific examples of such an onium salt type acid diffusion control agent include carboxylates and sulfonates described in Patent Document 1 and JP-A-2003-5376.

[0021] This onium salt-type acid diffusion control agent can be more effective in improving LWR and CDU than amine compounds, but it also reduces contrast. This is because the acid trapping by ion exchange is not an irreversible reaction but has a certain equilibrium. In other words, insufficient acid diffusion control leads to deterioration of contrast.

[0022] In contrast, the compound represented by formula (1) of the present invention not only has high LWR and CDU, but also has high contrast and therefore excellent resolution. This is believed to be because the compound represented by formula (1) does not undergo an equilibrium reaction like the onium salts, and has a high diffusion control function that does not re-release the trapped acid.

[0023] In the resist composition of the present invention, the content of the compound represented by formula (1) is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, relative to 80 parts by mass of the (C) base polymer described below. If the content of this compound is within the above range, it functions sufficiently as an acid diffusion control agent, and there is no risk of performance deterioration such as sensitivity reduction or generation of foreign matter due to insufficient solubility. The compound represented by formula (1) can be used alone or in combination of two or more kinds.

[0024] [Resist composition] The resist composition of the present invention contains as an essential component an acid diffusion controller made of a compound represented by formula (1) (A), and as other components (B) an organic solvent, (C) a polymer (base polymer) containing a repeating unit having an acid labile group, and (D) Photoacid generator Including, if necessary, (E) Other acid diffusion control agents and optionally further comprising (F) A surfactant may be included.

[0025] [(B) Organic solvent] The organic solvent of component (B) is not particularly limited as long as it can dissolve each component. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol, as described in paragraphs

[0144] and

[0145] of JP-A-2008-111103, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, Examples of the solvent 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; lactones such as γ-butyrolactone; and mixed solvents thereof. 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, etc., can also be added to accelerate the deprotection reaction of the acetal.

[0026] Among these organic solvents, 1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate, cyclohexanone, γ-butyrolactone, and mixed solvents thereof are preferred.

[0027] The amount of the (B) organic solvent used is preferably 200 to 5,000 parts by mass, and more preferably 400 to 3,000 parts by mass, relative to 80 parts by mass of the (C) base polymer described below. The (B) organic solvent can be used alone or in combination of two or more kinds.

[0028] [(C) Base polymer] The base polymer used in the resist composition of the present invention is a polymer containing a repeating unit having an acid labile group. The repeating unit having an acid labile group is preferably a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0029] In formulas (a1) and (a2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 11 - and X 11 X is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or a naphthylene group. 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. AL 1 and A.L. 2 are each independently an acid labile group.

[0030] In formula (a2), R 11 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1 ~R 4 and the same as those exemplified as the hydrocarbyl group having 1 to 20 carbon atoms represented by R. a is an integer of 0 to 4, and preferably 0 or 1.

[0031] X in formula (a1) 1 Examples of structures in which R is changed include, but are not limited to, those shown below. A and A.L. 1 is the same as above. [ka]

[0032] [ka]

[0033] A polymer containing the repeating unit a1 is decomposed by the action of an acid to produce a carboxyl group, and becomes alkali-soluble.

[0034] AL 1 and A.L. 2 The acid labile group represented by the formula (I) is not particularly limited, and preferred examples thereof include groups selected from the following formulae (L1) to (L4), tertiary hydrocarbyl groups having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, trihydrocarbylsilyl groups each of which has 1 to 6 carbon atoms, carbonyl groups, and hydrocarbyl groups containing an ether bond or an ester bond and having 4 to 20 carbon atoms. [ka] (In the formula, the dashed lines represent bonds.)

[0035] In formula (L1), R L01 and R L02 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-octyl group, and a 2-ethylhexyl group; and cyclic saturated hydrocarbyl groups such as a cyclopentyl group, a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, a tetracyclododecanyl group, and an adamantyl group.

[0036] R L03is a hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic, but is preferably a saturated hydrocarbyl group. In addition, some or all of the hydrogen atoms of the saturated hydrocarbyl group may be substituted with a hydroxy group, a saturated hydrocarbyloxy group, an oxo group, an amino group, a saturated hydrocarbylamino group, or the like, and some of the -CH2- constituting the saturated hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom. Examples of the saturated hydrocarbyl group include L01 and R L02 Examples of the saturated hydrocarbyl group represented by the formula (I) include the same as those mentioned above. Examples of the substituted saturated hydrocarbyl group include the groups shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0037] R L01 , R L02 and R L03 Any two of R may be bonded to each other to form a ring together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. When a ring is formed, R L01 , R L02 and R L03 It is preferable that any two of these are each independently an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms.

[0038] In formula (L2), R L04 is a tertiary hydrocarbyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group in which each alkyl group has 1 to 6 carbon atoms, a carbonyl group, a saturated hydrocarbyl group containing an ether bond or an ester bond and having 4 to 20 carbon atoms, or a group represented by formula (L1). x is an integer of 0 to 6.

[0039] R L04The tertiary hydrocarbyl group represented by the formula (I) may be branched or cyclic, and specific examples thereof include tert-butyl, tert-pentyl, 1,1-diethylpropyl, 2-cyclopentylpropan-2-yl, 2-cyclohexylpropan-2-yl, 2-(bicyclo[2.2.1]heptan-2-yl)propan-2-yl, 2-(adamantan-1-yl)propan-2-yl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, and 2-ethyl-2-adamantyl. The trialkylsilyl group includes trimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl. Examples of the saturated hydrocarbyl group containing a carbonyl group, an ether bond or an ester bond include a 3-oxocyclohexyl group, a 4-methyl-2-oxooxan-4-yl group, and a 5-methyl-2-oxooxolan-5-yl group.

[0040] In formula (L3), R L05is an optionally substituted saturated hydrocarbyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. The optionally substituted saturated hydrocarbyl group may be linear, branched or cyclic, and specific examples thereof include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl and n-hexyl groups; cyclic saturated hydrocarbyl groups such as cyclopentyl and cyclohexyl groups; and groups in which some or all of the hydrogen atoms of these groups have been substituted with a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a carboxy group, a saturated hydrocarbylcarbonyl group having 1 to 8 carbon atoms, an oxo group, an amino group, a saturated hydrocarbylamino group having 1 to 8 carbon atoms, a cyano group, a mercapto group, a saturated hydrocarbylthio group having 1 to 8 carbon atoms, a sulfo group or the like. Examples of the optionally substituted aryl group include a phenyl group, a methylphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, and groups in which some or all of the hydrogen atoms of these groups have been substituted with a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a carboxy group, a saturated hydrocarbylcarbonyl group having 1 to 8 carbon atoms, an oxo group, an amino group, a saturated hydrocarbylamino group having 1 to 8 carbon atoms, a cyano group, a mercapto group, a saturated hydrocarbylthio group having 1 to 8 carbon atoms, a sulfo group, or the like.

[0041] In formula (L3), y is 0 or 1; z is an integer of 0 to 3; and 2y+z=2 or 3.

[0042] In formula (L4), R L06 is an optionally substituted saturated hydrocarbyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. Specific examples of the optionally substituted saturated hydrocarbyl group and the optionally substituted aryl group include R L05 Examples of the compound represented by the formula (I) include the same compounds as those exemplified above.

[0043] In formula (L4), R L07 ~R L16are each independently a hydrogen atom or an optionally substituted hydrocarbyl group having 1 to 15 carbon atoms. The hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic, although a saturated hydrocarbyl group is preferred. Examples of the hydrocarbyl group include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, and n-decyl; cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, and cyclohexylbutyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with a hydroxy group, a saturated hydrocarbyloxy group having 1 to 8 carbon atoms, a carboxy group, a saturated hydrocarbyloxycarbonyl group having 1 to 8 carbon atoms, an oxo group, an amino group, a saturated hydrocarbylamino group having 1 to 8 carbon atoms, a cyano group, a mercapto group, a saturated hydrocarbylthio group having 1 to 8 carbon atoms, or a sulfo group. L07 ~R L16 Two selected from these may be bonded to each other to form a ring together with the carbon atom to which they are bonded (for example, R L07 and R L08 , R L07 and R L09 , R L07 and R L10 , R L08 and R L10 , R L09 and R L10 , R L11 and R L12 , R L13 and R L14 In this case, the group participating in the ring formation is a hydrocarbylene group having 1 to 15 carbon atoms. Examples of the hydrocarbylene group include those obtained by removing one hydrogen atom from the above-mentioned examples of the hydrocarbyl group. L07 ~R L16 may bond to adjacent carbon atoms without any intermediate bond to form a double bond (for example, R L07 and R L09 , RL09 and R L15 , R L13 and R L15 , R L14 and R L15 etc.).

[0044] Among the acid labile groups represented by formula (L1), linear or branched ones include the groups shown below, but are not limited to these. [ka] (In the formula, the dashed lines represent bonds.)

[0045] Among the acid labile groups represented by formula (L1), examples of cyclic groups include a tetrahydrofuran-2-yl group, a 2-methyltetrahydrofuran-2-yl group, a tetrahydropyran-2-yl group, and a 2-methyltetrahydropyran-2-yl group.

[0046] Examples of the acid labile group represented by formula (L2) include a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tert-pentyloxycarbonyl group, a tert-pentyloxycarbonylmethyl group, a 1,1-diethylpropyloxycarbonyl group, a 1,1-diethylpropyloxycarbonylmethyl group, a 1-ethylcyclopentyloxycarbonyl group, a 1-ethylcyclopentyloxycarbonylmethyl group, a 1-ethyl-2-cyclopentenyloxycarbonyl group, a 1-ethyl-2-cyclopentenyloxycarbonylmethyl group, a 1-ethoxyethoxycarbonylmethyl group, a 2-tetrahydropyranyloxycarbonylmethyl group, and a 2-tetrahydrofuranyloxycarbonylmethyl group.

[0047] Examples of the acid labile group represented by formula (L3) include a 1-methylcyclopentyl group, a 1-ethylcyclopentyl group, a 1-n-propylcyclopentyl group, a 1-isopropylcyclopentyl group, a 1-n-butylcyclopentyl group, a 1-sec-butylcyclopentyl group, a 1-cyclohexylcyclopentyl group, a 1-(4-methoxy-n-butyl)cyclopentyl group, a 1-methylcyclohexyl group, a 1-ethylcyclohexyl group, a 3-methyl-1-cyclopenten-3-yl group, a 3-ethyl-1-cyclopenten-3-yl group, a 3-methyl-1-cyclohexen-3-yl group, and a 3-ethyl-1-cyclohexen-3-yl group.

[0048] As the acid labile group represented by formula (L4), groups represented by the following formulae (L4-1) to (L4-4) are particularly preferred. [ka]

[0049] In the formulas (L4-1) to (L4-4), the dashed lines indicate the bond positions and bond directions. L41 are each independently a hydrocarbyl group having 1 to 10 carbon atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic, but is preferably a saturated hydrocarbyl group. Examples of the hydrocarbyl group include alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, and n-hexyl groups; and cyclic saturated hydrocarbyl groups such as cyclopentyl and cyclohexyl groups.

[0050] The groups represented by formulae (L4-1) to (L4-4) may have stereoisomers (enantiomers or diastereomers), and formulae (L4-1) to (L4-4) represent all of these stereoisomers. When the acid labile group is a group represented by formula (L4), it may contain multiple stereoisomers.

[0051] For example, formula (L4-3) represents one or a mixture of two selected from groups represented by the following formulae (L4-3-1) and (L4-3-2). [ka] (In the formula, R L41 is the same as above. The dashed lines indicate bonds.)

[0052] Moreover, the formula (L4-4) represents one or a mixture of two or more selected from the groups represented by the following formulae (L4-4-1) to (L4-4-4). [ka] (In the formula, R L41 is the same as above. The dashed lines indicate bonds.)

[0053] Formulae (L4-1) to (L4-4), (L4-3-1), (L4-3-2), and (L4-4-1) to (L4-4-4) are also intended to represent their enantiomers and mixtures of enantiomers.

[0054] In addition, the bonding directions of the formulae (L4-1) to (L4-4), (L4-3-1), (L4-3-2), and (L4-4-1) to (L4-4-4) are on the exo side of the bicyclo[2.2.1]heptane ring, respectively, thereby realizing high reactivity in the acid-catalyzed elimination reaction (see JP 2000-336121 A). In the production of a monomer having a tertiary exo-saturated hydrocarbyl group having a bicyclo[2.2.1]heptane skeleton as a substituent, a monomer substituted with an endo-alkyl group represented by the following formulae (L4-1-endo) to (L4-4-endo) may be included, but in order to realize good reactivity, the exo ratio is preferably 50 mol% or more, and more preferably 80 mol% or more. [ka] (In the formula, R L41 is the same as above. The dashed lines indicate bonds.)

[0055] Examples of the acid labile group represented by formula (L4) include, but are not limited to, the groups shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0056] Also, AL 1 and A.L. 2 Among the acid labile groups represented by the formula (I), tertiary hydrocarbyl groups having 4 to 20 carbon atoms, trihydrocarbylsilyl groups each of which is a hydrocarbyl group having 1 to 6 carbon atoms, and saturated hydrocarbyl groups having 4 to 20 carbon atoms and containing a carbonyl group, an ether bond or an ester bond are each represented by the formula (I): L04 Examples of the examples are similar to those given in the description of .

[0057] Examples of the repeating unit a1 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] These specific examples are X 1 is a single bond, but X 1 Even when X is other than a single bond, it can be combined with a similar acid labile group. 1 Specific examples of when is other than a single bond are as described above.

[0063] A polymer containing the repeating unit a2, like the repeating unit a1, is decomposed by the action of an acid to produce a hydroxyl group, and becomes alkali-soluble.

[0064] Examples of the repeating unit a2 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0065] [ka]

[0066] The base polymer preferably further contains a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0067] In formulas (b1) and (b2), R A is the same as above. Y 1 is a hydrogen atom, or a polar group containing at least one selected from a hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride. m is 1 or 2.

[0068] Examples of the repeating unit b1 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] Examples of the repeating unit b2 include, but are not limited to, those shown below. In the following formula, R Ais the same as above. [ka]

[0078] As the repeating unit b1 or b2, in ArF lithography, it is particularly preferable that the repeating unit has a lactone ring as a polar group, and in KrF lithography, EB lithography and EUV lithography, it is preferable that the repeating unit has a phenolic hydroxy group.

[0079] The base polymer may further contain a repeating unit represented by the following formula (c1) or (c2): These are repeating units having a photoacid generating group. [ka]

[0080] In formulas (c1) and (c2), R A is the same as above. 21 R is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 22 , R 23 and R 24 R is each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 21 , R 22 , R 23 and R 24 The hydrocarbyl group represented by may be saturated or unsaturated and may be linear, branched, or cyclic. Specific examples thereof include R 1 ~R 4 and the same as those exemplified as the hydrocarbyl group having 1 to 20 carbon atoms represented by R.

[0081] In formula (c1), L 11 is an alkanediyl group having 2 to 5 carbon atoms. 11Examples of the alkanediyl group represented by the formula (I) include an ethane-1,2-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,3-diyl group, and a butane-1,4-diyl group.

[0082] In formula (c2), L 12 L is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 12The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups such as methanediyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, and heptadecane-1,17-diyl group; and cyclopentanediyl group. cyclic saturated hydrocarbylene groups such as a cyclohexanediyl group, a norbornanediyl group, or an adamantanediyl group; and arylene groups such as a phenylene group, a methylphenylene group, an ethylphenylene group, an n-propylphenylene group, an isopropylphenylene group, an n-butylphenylene group, an isobutylphenylene group, a sec-butylphenylene group, a tert-butylphenylene group, a naphthylene group, a methylnaphthylene group, an ethylnaphthylene group, an n-propylnaphthylene group, an isopropylnaphthylene group, an n-butylnaphthylene group, an isobutylnaphthylene group, a sec-butylnaphthylene group, or a tert-butylnaphthylene group. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH2- of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0083] In formulas (c1) and (c2), R HF are each independently a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. p is 0 or 1. q is 0 or 1, but L 2When is a single bond, q is 0.

[0084] In formula (c1), specific examples of the anion structure include those described in JP-A-2010-113209 and JP-A-2007-145797. HF Specific examples of structures in which R is a hydrogen atom include those described in JP-A-2010-116550. HF In the case where is a trifluoromethyl group, examples thereof include those described in JP-A-2010-77404.

[0085] The base polymer may further contain other repeating units than those described above. For example, substituted acrylic esters such as methyl methacrylate, methyl crotonate, dimethyl maleate, and dimethyl itaconate; unsaturated carboxylic acids such as maleic acid, fumaric acid, and itaconic acid; norbornene, norbornene derivatives, tetracyclo[6.2.1.1 3,6 .0 2,7 ] The copolymer may contain repeating units derived from cyclic olefins such as dodecene derivatives; unsaturated acid anhydrides such as itaconic anhydride; or other monomers.

[0086] The weight average molecular weight (Mw) of the base polymer is preferably 1,000 to 500,000, more preferably 3,000 to 100,000. If Mw is within this range, sufficient etching resistance is obtained, and there is no risk of a decrease in resolution due to an inability to ensure a difference in dissolution rate before and after exposure. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0087] Furthermore, if the base polymer has a broad molecular weight distribution (Mw / Mn), low and high molecular weight polymers may be present, which may result in foreign matter being found on the pattern after exposure or deterioration of the pattern shape. Therefore, since the effects of Mw and Mw / Mn tend to become greater as the pattern rule becomes finer, in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the Mw / Mn of the base polymer has a narrow distribution of 1.0 to 2.0.

[0088] The (C) base polymer may use one type alone, or may use a combination of two or more types having different composition ratios, Mw and / or Mw / Mn.

[0089] As an example of a method for synthesizing the base polymer, a method in which a monomer that provides the above-mentioned repeating unit is polymerized by heating in an organic solvent with the addition of a polymerization initiator can be given.

[0090] Examples of the organic solvent used in the polymerization reaction include toluene, benzene, THF, diethyl ether, and dioxane. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (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 80°C. The reaction time is preferably 2 to 100 hours, and more preferably 5 to 20 hours. The acid labile group introduced into the monomer may be used as it is, or may be protected or partially protected after polymerization.

[0091] The preferred content ratio of each repeating unit in the base polymer can be, for example, within the ranges shown below, but is not limited thereto. (I) One or more repeating units represented by formula (a1) or (a2) are preferably contained in an amount of 1 to 60 mol %, more preferably 5 to 50 mol %, and even more preferably 10 to 50 mol %, (II) One or more repeating units represented by formula (b1) or (b2) are preferably contained in an amount of 40 to 99 mol %, more preferably 50 to 95 mol %, and even more preferably 50 to 90 mol %, (III) One or more repeating units derived from other monomers, preferably 0 to 50 mol %, more preferably 0 to 40 mol %, and even more preferably 0 to 30 mol %.

[0092] [(D) Photoacid generator] The resist composition of the present invention may further contain a photoacid generator that generates a strong acid in response to actinic rays or radiation. The strong acid referred to here means a compound having sufficient acidity to cause a deprotection reaction of the acid labile group of the base polymer.

[0093] The photoacid generator is not particularly limited as long as it is a compound that generates an acid when exposed to high-energy rays such as ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, excimer laser light, gamma rays, and synchrotron radiation. Suitable photoacid generators include photoacid generators such as sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxydicarboximide, O-arylsulfonyloximes, and O-alkylsulfonyloximes. Examples of these photoacid generators include those described in paragraphs

[0102] to

[0113] of JP 2007-145797 A.

[0094] A preferred photoacid generator is a sulfonium salt represented by the following formula (2). [ka]

[0095] In formula (2), R 101 , R 102 and R 103 R is each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 101 , R 102 and R 103The hydrocarbyl group having 1 to 20 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 20 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups such as decanyl group, adamantyl group, and adamantylmethyl group; aryl groups such as phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, and anthracenyl group; and groups obtained by combining these groups. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH2- of these groups may be interrupted by a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the 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, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a carbamate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like.

[0096] Also, R 101 and R 102 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is preferably one having the structure shown below. [ka] (In the formula, the dashed line represents R 103 It is a combination with .)

[0097] Examples of the sulfonium cation of the sulfonium salt represented by formula (2) include triphenylsulfonium, 4-hydroxyphenyldiphenylsulfonium, bis(4-hydroxyphenyl)phenylsulfonium, tris(4-hydroxyphenyl)sulfonium, 4-tert-butoxyphenyldiphenylsulfonium, bis(4-tert-butoxyphenyl)phenylsulfonium, tris(4-tert-butoxyphenyl)sulfonium, 3-tert-butoxyphenyldiphenylsulfonium, bis(3-tert-butoxyphenyldiphenylsulfonium, 4-tert-butoxycarbonylmethyloxyphenyl)phenylsulfonium, tris(3-tert-butoxyphenyl)sulfonium, 3,4-di-tert-butoxyphenyldiphenylsulfonium, bis(3,4-di-tert-butoxyphenyl)phenylsulfonium, tris(3,4-di-tert-butoxyphenyl)sulfonium, diphenyl(4-thiophenoxyphenyl)sulfonium, 4-tert-butoxycarbonylmethyloxyphenyldiphenylsulfonium, tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium 4-tert-butoxyphenylbis(4-dimethylaminophenyl)sulfonium, tris(4-dimethylaminophenyl)sulfonium, 2-naphthyldiphenylsulfonium, (4-hydroxy-3,5-dimethylphenyl)diphenylsulfonium, (4-n-hexyloxy-3,5-dimethylphenyl)diphenylsulfonium, dimethyl(2-naphthyl)sulfonium, 4-hydroxyphenyldimethylsulfonium, 4-methoxyphenyldimethylsulfonium, trimethylsulfonium, 2-oxophenyl Examples of cations include cyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium, tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium, 2-oxo-2-phenylethylthiacyclopentanium, diphenyl-2-thienylsulfonium, 4-n-butoxynaphthyl-1-thiacyclopentanium, 2-n-butoxynaphthyl-1-thiacyclopentanium, 4-methoxynaphthyl-1-thiacyclopentanium, and 2-methoxynaphthyl-1-thiacyclopentanium.

[0098] Furthermore, examples of the sulfonium cation of the sulfonium salt represented by formula (2) include those represented by the following formula: In the following formula, Me is a methyl group. [ka]

[0099] Of these, triphenylsulfonium, 4-tert-butylphenyldiphenylsulfonium, 4-tert-butoxyphenyldiphenylsulfonium, tris(4-tert-butylphenyl)sulfonium, tris(4-tert-butoxyphenyl)sulfonium, dimethylphenylsulfonium, and the like are preferred.

[0100] In formula (2), Xa - is an anion represented by any one of the following formulas (2A) to (2D). [ka]

[0101] 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.

[0102] As the anion represented by formula (2A), one represented by the following formula (2A') is particularly preferred. [ka]

[0103] In formula (2A'), R HF R is a hydrogen atom or a trifluoromethyl group. 111is a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom or a halogen atom, and more preferably an oxygen atom. In order to obtain high resolution in the formation of a fine pattern, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

[0104] R 111 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosanyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, Examples of the alkyl group include cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a norbornylmethyl 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.

[0105] In addition, some or all of the hydrogen atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the carbon atoms of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, resulting in the group containing a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0106] The synthesis of a sulfonium salt having an anion represented by formula (2A') is described in detail in JP-A-2007-145797, JP-A-2008-106045, JP-A-2009-7327, JP-A-2009-258695, and the like.

[0107] Examples of the anion represented by formula (2A) include, but are not limited to, nonafluorobutanesulfonate, the partially fluorinated sulfonates described in JP-A-2012-189977, paragraphs

[0247] to

[0251] , the partially fluorinated sulfonates described in JP-A-2013-101271, paragraphs

[0261] to

[0265] , and the anion shown below. In the following formula, Ac is an acetyl group. [ka]

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] 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. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 111 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 are bonded to each other and the group to which they are bonded (-CF2-SO2-N - -SO2-CF2-) may form a ring, in which case, R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0112] 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. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 111 Examples of the hydrocarbyl group represented by the formula 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 fc2are bonded to each other and the groups to which they are bonded (-CF2-SO2-C - -SO2-CF2-) may form a ring, in which case, R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0113] 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 R 111 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0114] The synthesis of the sulfonium salt having the anion represented by formula (2D) is described in detail in JP-A-2010-215608.

[0115] Examples of the anion represented by formula (2D) include, but are not limited to, those shown below. [ka]

[0116] [ka]

[0117] 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 group in the base polymer, and can therefore be used as a photoacid generator.

[0118] As the photoacid generator (D), a compound represented by the following formula (3) is also preferred. [ka]

[0119] In formula (3), R 201 and R 202 R is each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 203 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 201 , R 202 and R 203 Any two of may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is as defined in the explanation of formula (2) as R 101 and R 102 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, similar to those exemplified above.

[0120] R 201 and R 202 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl and 2-ethylhexyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclohexylmethyl, cyclohexylethyl, norbornyl, oxanorbornyl and tricyclo[5.2.1.0]. 2,6cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a decanyl group, and an adamantyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a methylphenyl group, an ethylphenyl group, an n-propylphenyl group, an isopropylphenyl group, an n-butylphenyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, and a tert-butylnaphthyl group; and groups obtained by combining these groups. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH2- of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, resulting in the group containing a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc. 201 and R 202 is preferably an aryl group in which a hydrogen atom may be substituted.

[0121] R 203The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups having 1 to 20 carbon atoms, such as a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, a tetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, a hexadecane-1,16-diyl group, and a heptadecane-1,17-diyl group; a cyclopentanediyl group, a cyclohexanediyl group, and the like. Examples of the aryl groups include cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as axanediyl group, norbornanediyl group, and adamantanediyl group; arylene groups having 6 to 30 carbon atoms, such as a phenylene group, a methylphenylene group, an ethylphenylene group, an n-propylphenylene group, an isopropylphenylene group, an n-butylphenylene group, an isobutylphenylene group, a sec-butylphenylene group, a tert-butylphenylene group, a naphthylene group, a methylnaphthylene group, an ethylnaphthylene group, an n-propylnaphthylene group, an isopropylnaphthylene group, an n-butylnaphthylene group, an isobutylnaphthylene group, a sec-butylnaphthylene group, and a tert-butylnaphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of these groups may be substituted with heteroatom groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the -CH2- of these groups may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms, resulting in the group containing a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, and the like. 203 is preferably an aryl group in which a hydrogen atom may be substituted.

[0122] In formula (3), G is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond or a heteroatom. The hydrocarbylene group represented by G may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 203 Examples of the hydrocarbylene group represented by the formula (1) include the same as those exemplified above. In addition, some or all of the hydrogen atoms of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- of these groups may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, they may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like. Of these, G is preferably a methylene group, or a methylene group in which a hydrogen atom is substituted with a fluorine atom or a trifluoromethyl group.

[0123] In formula (3), L x is a divalent linking group. Examples of the linking group include an ether bond, an ester bond, a thioether bond, a sulfinic acid ester bond, a sulfonic acid ester bond, a carbonate bond, and a carbamate bond.

[0124] Examples of the photoacid generator represented by formula (3) include the same as those exemplified as the photoacid generator represented by formula (3) in JP2018-062503A.

[0125] In the resist composition of the present invention, the content of the photoacid generator (D) is 0 to 40 parts by mass relative to 80 parts by mass of the base polymer (C), but when it is contained, it is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 20 parts by mass. This range is preferable because the resolution is good and there is no risk of problems with foreign matter occurring after resist development or during stripping. The photoacid generator (D) may be used alone or in combination of two or more kinds.

[0126] [(E) Other acid diffusion control agents] The resist composition of the present invention contains an acid diffusion controller represented by formula (1) (A) as an essential component, but may further contain an acid diffusion controller other than the compound represented by formula (1) (hereinafter, also referred to as other acid diffusion controller). Examples of the other acid diffusion controller include amine compounds and onium salt compounds. Examples of the amine compounds include primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond. In addition, compounds in which a primary or secondary amine is protected with a carbamate group, such as the compound described in JP-A-3790649, can also be mentioned. Examples of the onium salt compounds include the compounds described in the above-mentioned Patent Document 1 and JP-A-2003-005376.

[0127] Also, a sulfonium salt of sulfonic acid having a nitrogen-containing substituent may be used as the component (E). Such a compound functions as a quencher in the unexposed area, and functions as a so-called photodegradable base in the exposed area, losing the quenching ability by neutralization with the acid generated by itself. By using a photodegradable base, the contrast between the exposed area and the unexposed area can be further enhanced. For example, JP-A-2009-109595 and JP-A-2012-46501 can be referred to for the photodegradable base.

[0128] When the resist composition of the present invention contains another acid diffusion controller, the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, relative to 80 parts by mass of the base polymer (C). The other acid diffusion controller (E) may be used alone or in combination of two or more kinds.

[0129] [(F) Surfactant] The resist composition of the present invention may further contain a surfactant (F). The surfactant of the component (F) is preferably a surfactant that is insoluble or poorly soluble in water and an alkaline developer, or a surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer. As such a surfactant, reference can be made to those described in JP-A-2010-215608 and JP-A-2011-16746.

[0130] Among the surfactants described in the above publication that are insoluble or poorly soluble in water and an alkaline developer, preferred are FC-4430 (manufactured by 3M), Surflon (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Olfine (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and an oxetane ring-opening polymer represented by the following formula (surf-1): [ka]

[0131] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), regardless of the above description. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the aliphatic group include divalent ones such as ethylene group, 1,4-butylene group, 1,2-propylene group, 2,2-dimethyl-1,3-propylene group, and 1,5-pentylene group, and examples of trivalent or tetravalent ones include the following: [ka] (In the formula, the dashed lines represent bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0132] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferable.

[0133] 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 each constitutional unit in the formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of a partially fluorinated oxetane ring-opening polymer surfactant is described in detail in the specification of U.S. Pat. No. 5,650,483.

[0134] A surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer has a function of reducing water penetration and leaching by orienting on the surface of the resist film when a resist protective film is not used in ArF immersion exposure. Therefore, it is useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure device, and is also useful because it is soluble during development with an alkaline aqueous solution after exposure and post-exposure bake (PEB), and is unlikely to become a foreign matter that causes defects. Such surfactants are insoluble or poorly soluble in water and soluble in an alkaline developer, and are polymer-type surfactants, also called hydrophobic resins, and are particularly preferred for their high water repellency and improved water slippage.

[0135] Such polymeric surfactants include those containing at least one repeating unit selected from those represented by any of the following formulas (4A) to (4E). [ka]

[0136] In formulas (4A) to (4E), R B is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 R is -CH2-, -CH2CH2-, -O- or two -H separated from each other. s1are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 R are each independently a hydrogen atom, a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group. s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. s4 is a (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer of 1 to 3. s5 each independently represents a hydrogen atom or -C(=O)-OR s7 R is a group represented by the formula: s7 R is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 is a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be present between the carbon-carbon bonds.

[0137] 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.

[0138] R s2 The hydrocarbylene group represented by the formula (I) may be any of linear, branched, and cyclic, and specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group.

[0139] R s3 or R s6The hydrocarbyl group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include an alkyl group, an alkenyl group and an alkynyl group, with an alkyl group being preferred. s1 In addition to the examples of the hydrocarbyl group represented by the formula (I), examples of the hydrocarbyl group represented by the formula (I) include an 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 (1) include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbyl group described above have been substituted with fluorine atoms. As described above, an ether bond or a carbonyl group may be present between these carbon-carbon bonds.

[0140] R s3 Examples of the acid labile group represented by the formula (L1) to (L4) include the groups represented by the formulas (L1) to (L4) 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.

[0141] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by the formula (1) may be linear, branched, or cyclic, and specific examples thereof include groups obtained by further eliminating u hydrogen atoms from the above-mentioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0142] 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, and 2-(perfluorodecyl)ethyl group.

[0143] Examples of the repeating unit represented by any one of formulas (4A) to (4E) include, but are not limited to, those shown below. In the following formula, R B is the same as above. [ka]

[0144] [ka]

[0145] [ka]

[0146] [ka]

[0147] [ka]

[0148] The polymer surfactant may further contain other repeating units than the repeating units represented by formulae (4A) to (4E). Examples of the other repeating units include repeating units obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymer surfactant, the content of the repeating units represented by formulae (4A) to (4E) in the total repeating units is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %.

[0149] The Mw of the polymer surfactant is preferably from 1,000 to 50,000, and more preferably from 2,000 to 20,000. Within this range, the surface modification effect is sufficient and development defects are unlikely to occur.

[0150] The method for synthesizing the polymeric surfactant includes a method in which a monomer containing an unsaturated bond that gives the repeating units represented by formulae (4A) to (4E) and other repeating units as necessary is heated in an organic solvent with the addition of a radical initiator to polymerize. Examples of the organic solvent used during polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Examples of the polymerization initiator include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as it is, or may be protected or partially protected after polymerization.

[0151] When synthesizing the polymeric surfactant, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In this case, the amount of the chain transfer agent added is preferably 0.01 to 10 mol% based on the total moles of the monomers to be polymerized.

[0152] For the surfactant that is insoluble or slightly soluble in water and soluble in an alkaline developer, reference can also be made to JP-A-2008-122932, JP-A-2010-134012, JP-A-2010-107695, JP-A-2009-276363, JP-A-2009-192784, JP-A-2009-191151, JP-A-2009-98638, JP-A-2010-250105, JP-A-2011-42789, and the like.

[0153] The content of the (F) component is preferably 0 to 20 parts by mass relative to 80 parts by mass of the (C) base polymer. When the (F) component is contained, the lower limit is preferably 0.001 parts by mass, more preferably 0.01 parts by mass. Meanwhile, the upper limit is preferably 15 parts by mass, more preferably 10 parts by mass. The (F) surfactant may be used alone or in combination of two or more kinds.

[0154] [Pattern formation method] The pattern forming method of the present invention includes the steps of forming a resist film on a substrate using the resist composition, exposing the resist film to KrF excimer laser light, ArF excimer laser light, EB or EUV, and developing the exposed resist film using a developer.

[0155] The substrate may be, for example, a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective film, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.).

[0156] The resist film can be formed, for example, by applying the resist composition of the present invention by a method such as spin coating so that the film thickness is preferably 0.05 to 2 μm, and then pre-baking this on a hot plate preferably at 60 to 150° C. for 1 to 10 minutes, more preferably at 80 to 140° C. for 1 to 5 minutes. After the resist film is formed, the acid generator and the like may be extracted from the film surface or particles may be washed away by rinsing with pure water.

[0157] When KrF excimer laser light, ArF excimer laser light, or EUV is used for exposing the resist film, a mask for forming a desired pattern is used, and the exposure amount is preferably 1 to 200 mJ / cm. 2 , more preferably 10 to 100 mJ / cm 2 When EB is used, the exposure dose is preferably 1 to 300 μC / cm 2 , either directly or through a mask for forming a desired pattern. 2 , more preferably 10 to 200 μC / cm 2 Irradiate so that

[0158] In addition to the usual exposure method, the immersion method can be used in which a liquid with a refractive index of 1.0 or more is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0159] The water-insoluble protective film is used to prevent elution from the resist film and to increase the water sliding property of the film surface, and is roughly divided into two types. One is an organic solvent stripping type that needs to be stripped before alkaline aqueous solution development by an organic solvent that does not dissolve the resist film, and the other is an alkaline aqueous solution soluble type that is soluble in an alkaline developer and removes the protective film together with removing the soluble part of the resist film. The latter is based on a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and soluble in an alkaline developer, and is preferably a material dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixed solvent thereof. The above-mentioned water-insoluble and alkaline developer-soluble surfactant can also be dissolved in an alcohol-based solvent having 4 or more carbon atoms, an ether-based solvent having 8 to 12 carbon atoms, or a mixed solvent thereof.

[0160] After exposure, rinsing (post-soaking) may be performed to remove water remaining on the resist film. After exposure, heat treatment (PEB) may be performed as necessary. PEB can be performed, for example, by heating on a hot plate at preferably 60 to 150°C for 1 to 5 minutes, more preferably at 80 to 140°C for 1 to 3 minutes.

[0161] The development can be carried out, for example, using an alkaline aqueous developer such as 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 a dip method, a puddle method, a spray method, etc. The desired pattern is formed on the substrate by the development.

[0162] A pattern can also be formed by a double patterning method. Examples of double patterning methods include the trench method, in which the first exposure and etching process processes the base of a 1:3 trench pattern, then the position is shifted and the second exposure process forms a 1:3 trench pattern to form a 1:1 pattern, and the line method, in which the first base of a 1:3 isolated leave pattern is processed by the first exposure and etching process, then the position is shifted and the second exposure process forms a 1:3 isolated leave pattern on the second base formed under the first base, forming a 1:1 pattern with half the pitch.

[0163] In the pattern forming method of the present invention, a negative tone development can be carried out by using an organic solvent developer instead of the alkaline aqueous solution as the developer, in which the unexposed areas are dissolved.

[0164] Developers for this organic solvent development include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, Examples of the solvent include methyl crotonate, ethyl crotonate, 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, 2-phenylethyl acetate, etc. These solvents may be used alone or in combination of two or more. EXAMPLES

[0165] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The apparatus used is 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. LC / MS: Agilent Technologies 6100 Series Quadrupole LC / MS system

[0166] [1] Synthesis of acid diffusion control agent [Synthesis Example 1-1] Synthesis of Compound QA (3,3,3',3'-tetrakis(trifluoromethyl)-1λ4-1,1'-spirobi[3H-2,1-benzoxathiol]) [ka]

[0167] 2.1 g of N,N,N,N-tetramethylethylenediamine (TMEDA) was added dropwise to 32 mL of a hexane solution of n-butyllithium (n-BuLi) under ice cooling, and the mixture was aged for 30 minutes. Then, a mixed solution of 9.8 g of 1,1,1,3,3,3-hexafluoro-2-phenyl-2-propanol and THF was added dropwise under ice cooling, and the mixture was stirred for 20 hours, after which 50 g of THF was added to prepare a di-lithio compound. 21.2 g of thionyl chloride was charged in a separate vessel, and then the THF solution of the di-lithio compound was added dropwise under ice cooling, and the mixture was aged for 18 hours. Then, a saturated aqueous ammonium chloride solution was added to stop the reaction, and the organic layer was separated, washed with water, and concentrated under reduced pressure. Hexane was added to the concentrated residue to perform recrystallization, and the crystals were collected by filtration and dried under reduced pressure, obtaining 4.2 g of the target compound QA (yield 41%).

[0168] The spectral data of compound QA is shown below. Nuclear magnetic resonance spectrum ( 1 H-NMR / DMSO-d6) and ( 19 The results of F-NMR / DMSO-d6) are shown in Figures 1 and 2. 1 Traces of water were observed in H-NMR. IR(D-ATR): 3133, 1466, 1448, 1299, 1271, 1210, 1169, 1146, 1115, 1048, 972, 965, 956, 767, 738, 703, 679, 665, 571, 535, 526, 497cm -1 . LC / MS: POSITIVE [M+H] + 517

[0169] [Synthesis Example 1-2] Synthesis of Compound QB (1-chloro-1-[2-(1-hydroxy-1-methylethyl)phenyl]-3,3'-dimethyl[3H-2,1-benzoxathiol]) (1) Synthesis of intermediate In-1 (bis(2-carboxyphenyl)sulfide) [ka]

[0170] To a mixed solution of 15.4 g of thiosalicylic acid, 24.8 g of 2-iodobenzoic acid, 0.5 g of copper iodide, and N-methylpyrrolidone (NMP), 34.0 g of triethylamine was added dropwise at room temperature, and then the mixture was aged at 100°C for 15 hours. Dilute hydrochloric acid was added to the reaction solution, and the insoluble powder was collected by filtration. The collected powder was dissolved in methanol, and then recrystallized by adding pure water. The obtained crystals were filtered and dried under reduced pressure and heat, obtaining 23 g of the target intermediate In-1 (yield 84%).

[0171] (2) Synthesis of intermediate In-2 (2,2'-dicarboxydiphenyl sulfide dimethyl ester) [ka]

[0172] 19.2 g of intermediate In-1 was dissolved in 100 g of 1,3-dimethyl-2-imidazolidinone (DMI), 26.7 g of oxalyl chloride was added dropwise to this mixed solution at room temperature, and then the mixture was aged for 2 hours. Next, 100 g of methanol was added dropwise at room temperature, and the mixture was aged for 3 hours, after which 300 g of pure water was added to stop the reaction. Next, 200 g of toluene was added to separate the organic layer, and after washing with water, the mixture was concentrated under reduced pressure to remove the solvent, and 22.9 g of concentrated residue was obtained. This concentrated residue was used as intermediate In-2 for the next reaction.

[0173] (3) Synthesis of intermediate In-3 (bis[2-(1-hydroxy-1-methylethyl)phenyl]sulfide) [ka]

[0174] 22.9 g of intermediate In-2 was dissolved in 75 g of tetrahydrofuran, 100 g of a THF solution of methyl magnesium chloride was added dropwise under ice cooling, and the mixture was aged for 20 hours, after which dilute hydrochloric acid was added to stop the reaction. Then, 220 g of toluene was added to separate the organic layer, which was washed with water and then concentrated under reduced pressure to remove the solvent. 100 g of hexane was added to the concentrated residue to precipitate crystals, which were then filtered and dried under reduced pressure to obtain 15.7 g of the desired intermediate In-3 (yield 77%).

[0175] (4) Synthesis of intermediate In-4 (1-chloro-1-[2-(1-hydroxy-1-methylethyl)phenyl]-3,3'-dimethyl[3H-2,1-benzoxathiol]) [ka]

[0176] 9.1 g of intermediate In-3 was dissolved in 50 g of tert-butyl methyl ether (TBME), and 3.3 g of tert-butyl hypochlorite was added dropwise to the solution under ice cooling and aged for 3 hours. The powder was then filtered out from the reaction solution, washed with TBME, and dried under reduced pressure to obtain 8.2 g of the desired intermediate In-4 (yield 81%).

[0177] (5) Synthesis of compound QB (1-chloro-1-[2-(1-hydroxy-1-methylethyl)phenyl]-3,3'-dimethyl[3H-2,1-benzoxathiol]) [ka]

[0178] Aqueous sodium hydroxide solution was added dropwise to a mixed solution of 8.2 g of intermediate In-4 and 40 g of TBME at room temperature, and the mixture was aged for 1 hour. Then, 20 g of methyl isobutyl ketone was added thereto, and the organic layer was separated, washed with pure water, and then concentrated under reduced pressure. Hexane was added to the concentrated residue to precipitate crystals, and the obtained crystals were filtered and then dried under reduced pressure by heating, to obtain 5.1 g of the target compound QB (yield 73%).

[0179] The spectral data of compound QB is shown below. Nuclear magnetic resonance spectrum ( 1 The results of H-NMR / DMSO-d6) are shown in Figure 3. IR(D-ATR): 2974, 2928, 1468, 1446, 1436, 1374, 1357, 1285, 1251, 1165, 1156, 960, 945, 869, 782, 768, 743, 631, 622, 539, 532, 481, 458, 430 cm -1 . LC / MS: POSITIVE [M+H] + 301

[0180] [2] Synthesis of base polymer [Synthesis Example 2-1] Synthesis of Polymer P-1 In a nitrogen atmosphere, 19 g of 1-ethylcyclopentyl methacrylate, 17 g of 2-oxotetrahydrofuran-3-yl methacrylate, 0.48 g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 0.41 g of 2-mercaptoethanol, and 50 g of methyl ethyl ketone were placed in a flask to prepare a monomer-polymerization initiator solution. 23 g of methyl ethyl ketone was placed in another flask in a nitrogen atmosphere, and the mixture was heated to 80° C. with stirring, and the monomer-polymerization initiator solution was then dropped over 4 hours. After the dropwise addition, the temperature of the polymerization liquid was kept at 80° C. and the mixture was stirred for 2 hours, and then cooled to room temperature. The obtained polymerization liquid was dropped into 640 g of vigorously stirred methanol, and the precipitated polymer was filtered off. The obtained polymer was washed twice with 240 g of methanol, and then vacuum dried at 50° C. for 20 hours to obtain a white powdery polymer P-1 (yield 36 g, 90%). Analysis by GPC revealed that polymer P-1 had an Mw of 8,755 and an Mw / Mn of 1.94. [ka]

[0181] [Synthesis Examples 2-2 to 2-14] Synthesis of Polymers P-2 to P-14 Polymers P-2 to P-14 shown in the following Table 1 were produced in the same manner as in Synthesis Example 2-1, except that the types and compounding ratios of the monomers were changed. In Table 1, the introduction ratios are molar ratios.

[0182] [Table 1]

[0183] In Table 1, the structure of each repeating unit is as follows. [ka]

[0184] [ka]

[0185] [ka]

[0186] [3] Preparation of resist composition [Examples 1-1 to 1-18, Comparative Examples 1-1 to 1-6] The acid diffusion controllers QA and QB of the present invention, the acid diffusion controllers for comparison (Q-1 to Q-3), the base polymers (P-1 to P-14), the photoacid generator (PAG-X) and the alkali-soluble surfactant (SF-1) were dissolved in a solvent containing 0.01 mass % of surfactant A (manufactured by Omnova) in the compositions shown in Table 2 below to prepare solutions, and the solutions were then filtered through a 0.2 μm Teflon (registered trademark) filter to prepare resist compositions (R-01 to R-18, CR-01 to CR-06).

[0187] [Table 2]

[0188] In Table 2, the solvent, photoacid generator (PAG-X), alkali-soluble surfactant (SF-1), surfactant A and comparative acid diffusion controllers (Q-1 to Q-3) are as follows.

[0189] Solvent: PGMEA (propylene glycol monomethyl ether acetate) GBL (γ-butyrolactone)

[0190] Photoacid generator PAG-X: Triphenylsulfonium 2-(adamantane-1-carbonyloxy)-1,1,3,3,3-pentafluoropropane-1-sulfonate

[0191] Comparative acid diffusion control agent Q-1: Lauric acid 2-(4-morpholinyl)ethyl ester Q-2: Triphenylsulfonium 10-camphorsulfonate Q-3: Triphenylsulfonium salicylate [ka]

[0192] Alkaline-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 3,7 ]nonane-5-on-2-yl) Mw=7,700 Mw / Mn=1.82 [ka]

[0193] 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

[0194] [4] Evaluation of resist composition: ArF lithography evaluation (1) [Examples 2-1 to 2-10, Comparative Examples 2-1 to 2-3] A silicon substrate was coated with an anti-reflective coating solution (ARC29A manufactured by Nissan Chemical Co., Ltd.), and baked at 200°C for 60 seconds to prepare an anti-reflective coating (thickness 100 nm). On the substrate, each resist composition (R-01 to R-09, R-17, CR-01 to CR-03) was spin-coated and pre-baked at 90°C for 60 seconds using a hot plate to prepare a resist film with a thickness of 90 nm. This was subjected to immersion exposure using an ArF excimer laser scanner (Nikon Corporation, NSR-S610C, NA1.30, quadrupole, 6% halftone phase shift mask). Water was used as the immersion liquid. After that, the substrate was baked (PEB) for 60 seconds at the temperature shown in Table 3, and developed for 60 seconds with an aqueous solution of 2.38 mass% TMAH to form a line and space (LS) pattern.

[0195] The formed LS pattern was observed with a CD-SEM (CG-5000) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, LWR and collapse resistance were evaluated according to the following methods. The results are shown in Table 3.

[0196] [Sensitivity evaluation] For a 40 nm 1:1 line and space pattern, the optimal exposure dose Eop (mJ / cm) is used to obtain a line dimension width of 40 nm. 2 ) was decided.

[0197] [LWR rating] For the LS pattern obtained by irradiating at Eop, the dimensions were measured at 30 points along the longitudinal direction of the line, and the LWR was calculated as three times the standard deviation (σ) (3σ). The smaller the LWR value, the less fluctuation there is in the line pattern, and the better it is.

[0198] [Fall resistance evaluation] When the line dimension is narrowed by increasing the exposure dose, the minimum dimension at which the line can be resolved without collapsing is determined, and this is taken as the collapse limit (nm). The smaller the value, the higher the resistance to collapse, which is preferable.

[0199] [Table 3]

[0200] The results shown in Table 3 indicate that the resist composition of the present invention has excellent LWR and collapse resistance in alkali development positive pattern formation by ArF lithography, and is suitable as an ArF lithography material.

[0201] [5] Evaluation of resist composition: ArF lithography evaluation (2) [Examples 3-1 to 3-10, Comparative Examples 3-1 to 3-3] On a silicon wafer, a spin-on carbon film ODL-50 (carbon content 80% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. with a thickness of 200 nm and a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) with a thickness of 35 nm were formed on the silicon wafer. On the substrate for the trilayer process, each resist composition (R-01 to R-09, R-17, CR-01 to CR-03) was spin-coated, and then pre-baked at 100°C for 60 seconds using a hot plate to prepare a resist film with a thickness of 90 nm. This was subjected to immersion exposure through a photomask while changing the exposure dose and focus using an ArF excimer laser immersion scanner (Nikon Corporation, NSR-610C, NA 1.30, σ 0.98 / 0.74, cross-pole aperture 35 degrees). Water was used as the immersion liquid. Then, PEB was performed for 60 seconds at the temperature listed in Table 4, and development was performed for 30 seconds with a developer (butyl acetate). The photomask was a binary mask (design on the mask was 55 nm dots / 90 nm pitch (actual dimensions on the mask were 4 times larger due to 1 / 4 reduced projection exposure)) with a hole pattern of an inverted pattern formed on the resist film.

[0202] The formed hole pattern was observed with a CD-SEM (CG-5000) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, CDU and depth of focus (DOF) were evaluated according to the following methods. The results are shown in Table 4.

[0203] [Sensitivity evaluation] The optimal exposure dose Eop (mJ / cm) is the exposure dose at which the hole inner diameter becomes 50 nm. 2 ) was decided.

[0204] [CDU Rating] The dimensions of the obtained hole pattern at 50 points were measured, and the CDU was calculated as three times the standard deviation (σ). The smaller the CDU, the better the result.

[0205] [Depth of focus (DOF) evaluation] The focus range in which the hole pattern was resolved at Eop was determined and used as the DOF. The larger the DOF value, the wider the allowable margin for focus fluctuation, which is preferable.

[0206] [Table 4]

[0207] The results shown in Table 4 indicate that the resist composition of the present invention has excellent CDU and DOF in negative pattern formation by organic solvent development, and is extremely effective for fine processing by ArF lithography.

[0208] [6] Evaluation of resist composition: EUV lithography evaluation [Examples 4-1 to 4-8, Comparative Examples 4-1 to 4-3] Each resist composition (R-10 to R-18, CR-04 to CR-06) was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. was formed to a thickness of 20 nm, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 40 nm. A 22 nm line and space (LS) 1:1 pattern was exposed using an EUV scanner NXE3300 (NA 0.33, σ 0.9, 90-degree dipole illumination) manufactured by ASML, and then PEB was performed on a hot plate at the temperature listed in Table 5 for 60 seconds, and development was performed with a 2.38% by mass TMAH aqueous solution for 30 seconds to form an LS pattern.

[0209] The formed LS pattern was observed with a CD-SEM (CG-5000) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, LWR and limiting resolution were evaluated according to the following methods. The results are shown in Table 5.

[0210] [Sensitivity evaluation] The optimal exposure dose Eop (mJ / cm) for obtaining an LS pattern with a space width of 22 nm and a pitch of 44 nm is defined as 2 ) was decided.

[0211] [LWR rating] For the LS pattern obtained by irradiation at Eop, the dimensions of 10 points in the longitudinal direction of the space width were measured, and the LWR was calculated as three times the standard deviation (σ). The smaller this value, the smaller the roughness and the more uniform the space width pattern.

[0212] [Limiting resolution evaluation] Eop(mJ / cm 2 The minimum line width (nm) of the lines and spaces separated in the lattice pattern was defined as the limiting resolution.

[0213] [Table 5]

[0214] The results shown in Table 5 demonstrate that the resist composition of the present invention is excellent in sensitivity, LWR, and resolution even in positive pattern formation by alkaline solvent development in EUV lithography.

Claims

1. A resist composition comprising: (A) a compound represented by any one of the following formulae; (B) an organic solvent; (C) a base polymer including a repeating unit having an acid labile group; and (D) a photoacid generator. 【Chemistry 1】

2. A resist composition comprising: (A) a compound represented by any one of the following formulas, (B) an organic solvent, and (C) a base polymer containing a repeating unit having an acid labile group and a repeating unit having a photoacid generating group: 【Chemistry 2】

3. The resist composition according to claim 1 or 2, wherein the component (A) is a compound represented by any one of the following formulas: 【Chemistry 3】

4. 4. The resist composition according to claim 1, wherein the repeating unit having an acid labile group is represented by the following formula (a1) or (a2): 【Chemistry 4】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X 11 - and X 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. X 2 is a single bond or *-C(=O)-O-. * indicates a bond to a carbon atom in the main chain. A.L. 1 and A.L. 2 are each independently an acid labile group. R 11 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. a is an integer from 0 to 4.

5. 5. The resist composition according to claim 1, wherein the base polymer further comprises a repeating unit represented by the following formula (b1) or (b2): 【Chemistry 5】 (In the formula, R A is the same as above. Y 1 is a hydrogen atom, or a polar group containing at least one selected from a hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic acid anhydride. m is 1 or 2.

6. 6. The resist composition according to claim 1, further comprising (E) an acid diffusion controller other than the compound represented by formula (1).

7. 7. The resist composition according to claim 1, further comprising: (F) a surfactant.

8. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist composition according to any one of claims 1 to 7; exposing the resist film to KrF excimer laser light, ArF excimer laser light, an electron beam or extreme ultraviolet light; and developing the exposed resist film using a developer.

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