Resist material and pattern forming method

Abstract

To provide a resist composition that exhibits high sensitivity and is improved in the LWR and CDU, and a pattern forming process employing the same.SOLUTION: The resist composition comprises an acid generator comprising a sulfonium salt represented by the formula (1) in the figure.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming increasingly miniaturized. This is due to the growing popularity of 5G high-speed communications and artificial intelligence (AI), which requires high-performance devices to process these technologies. The most advanced miniaturization technology is extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, which is currently used to mass-produce 5 nm node devices. Furthermore, the use of EUV lithography is being considered for next-generation 3 nm node and the next-generation 2 nm node devices, and Belgium's IMEC has announced the development of 1 nm and 0.7 nm devices.

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

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

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

[0006] To form finer patterns, it is necessary not only to suppress acid diffusion but also to improve dissolution contrast. To improve dissolution contrast, polarity-switching base polymers that generate phenolic or carboxyl groups upon acid-induced deprotection are used. Resist materials containing these polymers can be used to form positive-tone patterns by alkaline development or negative-tone patterns by organic solvent development, with positive-tone patterns achieving higher resolution. This is because alkaline development results in higher dissolution contrast. Furthermore, base polymers that generate carboxyl groups have higher alkaline solubility than base polymers that generate phenolic groups, allowing for higher dissolution contrast. Therefore, carboxyl-group-generating base polymers are increasingly being used.

[0007] Non-chemically amplified main chain decomposition resist materials, which use a copolymer of α-chloroacrylate and α-methylstyrene as the base polymer, have a backbone that decomposes upon exposure, reducing the molecular weight and improving solubility in organic solvent developers. While they are not affected by acid diffusion, they have low dissolution contrast. Chemically amplified resist materials with the polarity conversion function described above offer higher resolution.

[0008] To further improve dissolution contrast, it has been proposed to add an acid generator with polarity conversion functionality to a resist material in addition to a base polymer with polarity conversion functionality. Patent Documents 3 and 4 disclose resist materials containing sulfonium salts with a tertiary ester-type acid labile group in the cation moiety, while Patent Documents 5 and 6 disclose resist materials containing sulfonium salts with an acid labile group in the anion moiety. However, the alicyclic structure-type or dimethylphenylcarbinol-type acid labile groups disclosed in these documents were insufficient in improving dissolution contrast and reducing swelling. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-045311 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-178317 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-006400 [Patent Document 4] Patent Publication No. 2021-070692 [Patent Document 5] Japanese Patent Application Laid-Open No. 2014-224236 [Patent Document 6] International Publication No. 2021 / 200056 [Non-patent literature]

[0010] [Non-Patent Document 1] SPIE Vol. 6520 65203L-1 (2007) Summary of the Invention [Problem to be solved by the invention]

[0011] In resist materials, there is a need for the development of acid generators that can improve line width write (LWR) and hole dimension uniformity (CDU) while also increasing sensitivity. To achieve this, it is necessary to further improve the dissolution contrast during development.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist material, particularly a positive resist material, that has high sensitivity and improved LWR and CDU, and a pattern formation method using the same. [Means for solving the problem]

[0013] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered that a resist material containing a sulfonium salt having a tertiary ester-type acid labile group having an aromatic group in the cation moiety exhibits excellent acid-induced elimination reactivity and high affinity with alkaline developers, resulting in high contrast and low swelling properties, and thereby enabling the production of a resist material with improved LWR and CDU, excellent resolution, and a wide process margin, thereby completing the present invention.

[0014] That is, the present invention provides the following resist material and pattern forming method. 1. A resist material containing an acid generator containing a sulfonium salt represented by the following formula (1): [ka] (In the formula, m is an integer of 0 to 5, n is an integer of 0 to 3, p is 0 or 1, q is an integer of 0 to 4, r is 1 or 2, and s is an integer of 1 to 3. R 1 is a single bond, an ether bond, a thioether bond or an ester bond. R 2 represents a single bond or an alkanediyl group having 1 to 20 carbon atoms, and the alkanediyl group may have a fluorine atom or a hydroxy group. R 3 and R 4are each independently a saturated hydrocarbyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the saturated hydrocarbyl group, alkenyl group, alkynyl group, and aryl group may contain an oxygen atom or a sulfur atom. 3 and R 4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 5 represents a fluorine atom, an iodine atom, an alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, an alkoxy group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, or an alkylthio group having 1 to 4 carbon atoms which may be substituted with a fluorine atom. R 6 is a hydroxy group, an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group, a cyano group, a chlorine atom, a bromine atom, or an amino group. R 7 represents a hydroxy group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an amino group, or a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, which may contain at least one selected from a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, an amino group, and an ether bond. R 8 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. When s=1, two R 8 may be the same or different and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. Ar is an aromatic group having 6 to 18 carbon atoms and a valence of (m+n+1) or a cyclic aliphatic hydrocarbon group having 5 to 10 carbon atoms and a valence of (m+n+1) containing a double bond, and may contain an oxygen atom, a sulfur atom, or a nitrogen atom. 3 and R 4If both are methyl groups and m=n=0, then circle Ar is not a phenyl group. X - is a non-nucleophilic counterion. 2. The resist material of 1, wherein the non-nucleophilic counter ion is a sulfonate anion, an imide anion, or a methide anion. 3. The resist material of 1 or 2, wherein m is an integer of 1 to 5. 4. The resist material of any one of 1 to 3, further comprising an organic solvent. 5. A resist material according to any one of 1 to 4, further comprising a base polymer. 6. The resist material according to 5, wherein the base polymer contains a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one bond selected from an ester bond, an ether bond, and a lactone ring. X 2 is a single bond or an ester bond. X 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and some of the -CH2- groups in the alkanediyl group may be substituted with ether bonds or ester bonds. a is 1 or 2, and b is an integer from 0 to 4, provided that 1≦a+b≦5. 7. The resist material of 6, which is a chemically amplified positive resist material. 8. The resist material of any one of 5 to 7, wherein the base polymer contains at least one repeating unit selected from the repeating units represented by the following formulas (f1) to (f3): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Z 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z 2 is a single bond or an ester bond. Z 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 represents a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51-, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a hydroxy group, or a halogen atom. R 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. M - is a non-nucleophilic counterion. 9. The resist material according to any one of 1 to 8, further comprising a surfactant. 10. A pattern forming method comprising the steps of forming a resist film on a substrate using a resist material according to any one of 1 to 9, exposing the resist film to high-energy rays, and developing the exposed resist film using a developer. 11. The pattern formation method according to 10, wherein the high-energy beam is KrF excimer laser light, ArF excimer laser light, an electron beam (EB), or EUV having a wavelength of 3 to 15 nm. [Effects of the Invention]

[0015] When a resist material containing the sulfonium salt represented by formula (1) contains a base polymer containing an acid labile group, not only does the resist material improve its alkaline dissolution rate due to the polarity change caused by the acid-catalyzed reaction generated by exposure, as with conventional acid generators, but the acid generator itself does not dissolve in the developer in the unexposed areas, while the acid generated from the acid generator generates carboxyl groups in the exposed areas, improving the alkaline dissolution rate. These features make it possible to develop resist materials with improved LWR and CDU. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Resist materials] The resist material of the present invention contains an acid generator that contains a sulfonium salt having, in the cation thereof, a tertiary ester-type acid labile group having an aromatic group.

[0017] [Sulfonium salts having an aromatic tertiary ester-type acid labile group as the cation] The sulfonium salt having a tertiary ester-type acid labile group having an aromatic group in the cation is represented by the following formula (1). [ka]

[0018] In formula (1), m is an integer of 0 to 5, n is an integer of 0 to 3, p is 0 or 1, q is an integer of 0 to 4, r is 1 or 2, and s is an integer of 1 to 3. m is preferably an integer of 1 to 5.

[0019] In formula (1), R 1 is a single bond, an ether bond, a thioether bond or an ester bond, and is preferably an ether bond or an ester bond.

[0020] In formula (1), R 2is a single bond or an alkanediyl group having 1 to 20 carbon atoms, and the alkanediyl group may have a fluorine atom or a hydroxy group. Examples of the alkanediyl group include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4- Examples thereof include a diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2-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, and a dodecane-1,12-diyl group.

[0021] In formula (1), R 3 and R 4 are each independently a saturated hydrocarbyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the saturated hydrocarbyl group, alkenyl group, alkynyl group, and aryl group may contain an oxygen atom or a sulfur atom. 3 and R 4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0022] R 3 and R 4 The saturated hydrocarbyl group having 1 to 12 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, and n-hexyl groups; and cyclic saturated hydrocarbyl groups having 3 to 12 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. 3 and R 4Examples of the alkenyl group having 2 to 8 carbon atoms represented by R include a vinyl group, a 1-propenyl group, a 2-propenyl group, a butenyl group, and a hexenyl group. 3 and R 4 Examples of the alkynyl group having 2 to 8 carbon atoms represented by R include an ethynyl group and a butynyl group. 3 and R 4 Examples of the aryl group having 6 to 10 carbon atoms represented by the formula include a phenyl group and a naphthyl group.

[0023] In formula (1), R 5 is a fluorine atom, an iodine atom, an alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, an alkoxy group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, or an alkylthio group having 1 to 4 carbon atoms which may be substituted with a fluorine atom. 5 The acid labile group is preferably a fluorine atom, a fluorine atom-substituted alkyl group having 1 to 4 carbon atoms, a fluorine atom-substituted alkoxy group having 1 to 4 carbon atoms, or a fluorine atom-substituted alkylthio group having 1 to 4 carbon atoms. By having an acid labile group having a fluorine atom in the cation, high dissolution contrast can be obtained.

[0024] In formula (1), R 6 is a hydroxy group, an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group, a cyano group, a chlorine atom, a bromine atom, or an amino group.

[0025] In formula (1), R 7 represents a hydroxy group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an amino group, or a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, which may contain at least one selected from a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, an amino group, and an ether bond.

[0026] R 7 The saturated hydrocarbyl groups represented by the formula (I) and the saturated hydrocarbyl moieties of the saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxycarbonyl group and saturated hydrocarbylsulfonyloxy group may be linear, branched or cyclic, and specific examples thereof include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-pentadecyl group or an n-hexadecyl group; and cyclic saturated hydrocarbyl groups such as a cyclopentyl group or a cyclohexyl group.

[0027] In formula (1), R 8 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 saturated hydrocarbyl groups having 1 to 20 carbon atoms, unsaturated aliphatic hydrocarbyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, aralkyl groups having 7 to 20 carbon atoms, and groups obtained by combining these groups.

[0028] The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups such as a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-pentadecyl group, and n-hexadecyl group; and cyclic saturated hydrocarbyl groups such as a cyclopentyl group and cyclohexyl group.

[0029] The unsaturated aliphatic hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include alkenyl groups such as vinyl, 1-propenyl, 2-propenyl, butenyl, and hexenyl; alkynyl groups such as ethynyl, propynyl, and butynyl; and cyclic unsaturated hydrocarbyl groups such as cyclohexenyl.

[0030] Examples of the aryl group include 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.

[0031] Examples of the aralkyl group include a benzyl group and a phenethyl group.

[0032] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, or some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a carboxy group, a halogen atom, a cyano group, an amino group, a nitro group, a sultone ring, a sulfo group, a sulfonium salt-containing group, an ether bond, an ester bond, a carbonyl group, a sulfide bond, a sulfonyl group, an amide bond or the like.

[0033] When s=1, two R 8 may be the same or different, and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring preferably has the following structure: [ka] (In the formula, the dashed line represents a bond to the aromatic ring in formula (1).)

[0034] In formula (1), the circle Ar represents an aromatic group having 6 to 18 carbon atoms and a valence of (m+n+1) or a cyclic aliphatic hydrocarbon group having 5 to 10 carbon atoms and a valence of (m+n+1) containing a double bond, and may contain an oxygen atom, a sulfur atom, or a nitrogen atom. 3 and R 4 are both methyl groups, and when m=n=0, the circle Ar is not a phenyl group. Examples of the aromatic group include groups obtained by removing (m+n+1) hydrogen atoms from an aromatic ring of benzene, toluene, o-xylene, m-xylene, p-xylene, naphthalene, etc. Examples of the double bond-containing cycloaliphatic hydrocarbon group include groups obtained by removing (m+n+1) hydrogen atoms from a ring of cycloaliphatic hydrocarbons such as cyclopentene, cyclopentadiene, cyclohexene, and norbornene.

[0035] The base polymer and the sulfonium salt undergo an acid-catalyzed deprotection reaction of their acid-labile groups, dissolving in an alkaline developer, resulting in even higher dissolution contrast. This allows for even higher sensitivity, smaller LWR, and improved CDU. Furthermore, the exposure dose at which the solubility of the base polymer improves through the deprotection reaction is the same as the exposure dose at which the sulfonium salt dissolves, thereby further enhancing contrast.

[0036] When the acid labile group of the base polymer and the acid labile group of the sulfonium salt have the same structure, the sulfonium salt present in the vicinity of the generated acid is more likely to undergo a deprotection reaction, and even if deprotection reactions occur simultaneously, the sulfonium salt with a smaller molecular weight will dissolve in an alkaline developer at a lower exposure dose. Conventional sulfonium salts substituted with acid labile groups have the same acid labile group as the base polymer, and therefore have a low effect of improving dissolution contrast due to the gap in deprotection reactivity between the base polymer and the sulfonium salt.

[0037] In the present invention, in order to eliminate the gap in deprotection reactivity between the base polymer and the sulfonium salt, it is preferable to use an acid labile group of the sulfonium salt that has a lower deprotection reactivity than the acid labile group of the base polymer. For example, in the case of an acid labile group containing an aromatic group, the deprotection reactivity can be adjusted to be low by introducing an electron-withdrawing group such as a halogen atom, a cyano group, or a nitro group into the aromatic group.

[0038] Examples of the cation of the sulfonium salt represented by formula (1) include, but are not limited to, those shown below. [ka]

[0039] [ka]

[0040] [ka]

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[0087] In formula (1), X -is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0088] Other examples of the non-nucleophilic counter ion include anions selected from the following formulae (1A) to (1D). [ka]

[0089] In formula (1A), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A') described below. fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0090] The anion represented by formula (1A) is preferably one represented by the following formula (1A'). [ka]

[0091] In formula (1A'), R HFis a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. fa1 is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. In order to obtain high resolution in the formation of a fine pattern, the hydrocarbyl group is particularly preferably one having 6 to 30 carbon atoms.

[0092] R fa1 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 38 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, 2-ethylhexyl, nonyl, undecyl, tridecyl, pentadecyl, heptadecyl, and icosanyl groups; cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, 1-adamantylmethyl, norbornyl, and norbornyl groups. Examples of such groups include saturated cyclic hydrocarbyl groups having 3 to 38 carbon atoms, such as an allyl group, a tricyclodecanyl group, a tetracyclododecanyl group, a tetracyclododecanylmethyl group, and a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 38 carbon atoms, such as an allyl group and a 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, and a 9-fluorenyl group; aralkyl groups having 7 to 38 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these groups.

[0093] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of hydrocarbyl groups containing hetero atoms include tetrahydrofuryl, methoxymethyl, ethoxymethyl, methylthiomethyl, acetamidomethyl, trifluoroethyl, (2-methoxyethoxy)methyl, acetoxymethyl, 2-carboxy-1-cyclohexyl, 2-oxopropyl, 4-oxo-1-adamantyl, and 3-oxocyclohexyl groups.

[0094] Examples of the anion represented by formula (1A) include, but are not limited to, those shown below: In the following formula, Ac is an acetyl group. [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] In formula (1B), R fb1 and R fb2are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A'). fa1 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 means that the groups to which they are bonded (-CF2-SO2-N - -SO2-CF2-) together to form a ring, in which case, R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0099] In formula (1C), R fc1 , R fc2 and R fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A'). fa1 Examples of the hydrocarbyl group represented by R include the same as those exemplified above. fc1 , R fc2 and R fc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are groups that are bonded together and bonded to each other (-CF2-SO2-C - -SO2-CF2-) together to form a ring, in which case, R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0100] In formula (1D), R fdis a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R in formula (1A'). fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0101] Examples of the anion represented by formula (1D) include, but are not limited to, those shown below. [ka]

[0102] [ka]

[0103] Further examples of the non-nucleophilic counter ion include anions having an aromatic ring substituted with an iodine atom or a bromine atom, such as those represented by the following formula (1E): [ka]

[0104] In formula (1E), x is an integer that satisfies 1≦x≦3. y and z are integers that satisfy 1≦y≦5, 0≦z≦3, and 1≦y+z≦5. y is preferably an integer that satisfies 1≦y≦3, more preferably 2 or 3. z is preferably an integer that satisfies 0≦z≦2.

[0105] In formula (1E), X BI is an iodine atom or a bromine atom, and when x and / or y are 2 or more, they may be the same or different.

[0106] In formula (1E), L 1is a single bond, an ether bond, an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched, or cyclic.

[0107] In formula (1E), L 2 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when x is 1, and represents an (x+1)-valent linking group having 1 to 20 carbon atoms when x is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0108] In formula (1E), R 9 is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 10 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms or a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or 9A )(R 9B ), -N(R 9C )-C(=O)-R 9D or -N(R 9C )-C(=O)-OR 9D R 9A and R 9B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 9C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. 9Dis an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When x and / or z is 2 or more, each R 9 may be the same or different from each other.

[0109] Of these, R 9 Examples of the hydroxyl group include -N(R 9C )-C(=O)-R 9D , -N(R 9C )-C(=O)-OR 9D fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, etc. are preferred.

[0110] In formula (1E), Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of them is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine to form a carbonyl group. 3 and Rf 4 are preferably both fluorine atoms.

[0111] Examples of the anion represented by formula (1E) include, but are not limited to, the following: BI is the same as above. [ka]

[0112]

change

[0113]

change

[0114]

change

[0115]

change

[0116]

change

[0117]

change

[0118]

change

[0119]

change

[0120]

change

[0121]

change

[0122]

change

[0123]

change

[0124]

change

[0125]

change

[0126]

change

[0127]

change

[0128]

change

[0129]

change

[0130]

change

[0131]

change

[0132]

change

[0133] [ka]

[0134] Examples of the non-nucleophilic counter ion include a fluorobenzenesulfonate anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, an anion having a mechanism for decomposing with an acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-070692, an anion having a cyclic ether group as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935, and an anion as described in Japanese Patent Application Publication No. 2018-092159.

[0135] Further examples of the non-nucleophilic counter ion include anions of bulky benzenesulfonic acid derivatives that do not contain fluorine atoms, as described in JP 2006-276759 A, JP 2015-117200 A, JP 2016-65016 A, and JP 2019-202974 A, and benzenesulfonic acid anions and alkylsulfonic acid anions that do not contain fluorine atoms bonded to aromatic groups containing iodine atoms, as described in Japanese Patent No. 6645464 A.

[0136] Further examples of the non-nucleophilic counter ion include anions of bissulfonic acid described in JP 2015-206932 A, anions of sulfonamides or sulfonimides having a sulfonic acid on one side and a different sulfonic acid on the other side described in WO 2020 / 158366 A, and anions of sulfonic acid on one side and carboxylic acid on the other described in JP 2015-024989 A.

[0137] The sulfonium salt represented by formula (1) can be synthesized by ion-exchanging the weak acid salt of the sulfonium cation described above with the ammonium salt having the non-nucleophilic counter ion.

[0138] In the resist material of the present invention, the content of the sulfonium salt represented by formula (1) is preferably 0.01 to 1,000 parts by mass, and more preferably 0.05 to 500 parts by mass, per 100 parts by mass of the base polymer described below, from the viewpoints of sensitivity and acid diffusion suppression effect.

[0139] [Base polymer] In the case of a positive resist material, the base polymer contained in the resist material of the present invention contains 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]

[0140] In formulas (a1) and (a2), R A are each independently a hydrogen atom or a methyl group. 1 X is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one bond selected from an ester bond, an ether bond, and a lactone ring. 2 is a single bond or an ester bond. 3 is a single bond, an ether bond, or an ester bond. 11 and R 12 are each independently an acid labile group. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and some of the -CH2- groups in the alkanediyl group may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer of 0 to 4, with the proviso that 1≦a+b≦5.

[0141] Examples of monomers that provide the repeating unit a1 include, but are not limited to, the following: A and R 11 is the same as above. [ka]

[0142] Examples of the monomer that provides the repeating unit a2 include, but are not limited to, the following: A and R 12 is the same as above. [ka]

[0143] In formulas (a1) and (a2), R 11 and R 12 Examples of the acid labile group represented by the formula (I) include those described in JP-A Nos. 2013-80033 and 2013-83821.

[0144] Typical examples of the acid labile group include those represented by the following formulae (L-1) to (L-3). [ka] (In the formula, the dashed lines represent bonds.)

[0145] In formulas (L-1) and (L-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 40 carbon atoms, more preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms.

[0146] In formula (L-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferred.

[0147] In formula (L-2), R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain heteroatoms such as oxygen, sulfur, nitrogen, and fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L2 , R L3 and R L4 Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0148] In formula (L-3), R L5 , R L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. In addition, R L5 , R L6 and R L7 Any two of these may be bonded to each other together with the carbon atoms to which they are bonded to form a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferred, and an alicyclic ring is particularly preferred.

[0149] The base polymer may contain a repeating unit b containing a phenolic hydroxy group as an adhesive group. Examples of monomers that provide the repeating unit b include, but are not limited to, the following. In the following formula, R A is the same as above. [ka]

[0150] The base polymer may contain a repeating unit c containing, as another adhesive group, a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonate ester bond, a carbonyl group, a sulfonyl group, a cyano group, or a carboxy group. Examples of monomers that provide the repeating unit c include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] The base polymer may contain repeating units d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Monomers that provide repeating units d include, but are not limited to, the following: [ka]

[0159] The base polymer may include repeat units e derived from styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, methyleneindane, vinylpyridine, or vinylcarbazole.

[0160] The base polymer may contain a repeating unit f derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units f include a repeating unit represented by the following formula (f1) (hereinafter also referred to as repeating unit f1), a repeating unit represented by the following formula (f2) (hereinafter also referred to as repeating unit f2), and a repeating unit represented by the following formula (f3) (hereinafter also referred to as repeating unit f3). The repeating units f1 to f3 may be used alone or in combination of two or more. [ka]

[0161] In formulas (f1) to (f3), R A are each independently a hydrogen atom or a methyl group. 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 11Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 represents a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. Z 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a hydroxy group, or a halogen atom.

[0162] In formulas (f1) to (f3), R 21 ~R 28 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 8Examples of the hydrocarbyl group include the same as those exemplified above. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of the -CH2- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, so that the hydrocarbyl group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be formed by bonding two R 8 are bonded to each other to form a ring together with the sulfur atom to which they are bonded, the same as those exemplified above.

[0163] In formula (f1), M - is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0164] Also, M - As the non-nucleophilic counter ion represented by the formula (1), an anion represented by any one of the formulae (1A) to (1E) can also be used.

[0165] Examples of the cation of the monomer that gives the repeating unit f1 include, but are not limited to, the following: A is the same as above. [ka]

[0166] Specific examples of the cation of the monomer that provides the repeating unit f2 or f3 include the sulfonium cations described in JP-A-2017-219836.

[0167] Examples of the anion of the monomer that gives the repeating unit f2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179] Examples of the anion of the monomer that gives the repeating unit f3 include, but are not limited to, those shown below. A is the same as above. [ka]

[0180] By bonding the acid generator to the polymer backbone, acid diffusion can be reduced, preventing a decrease in resolution due to blurred acid diffusion. Furthermore, the uniform dispersion of the acid generator improves LWR and CDU.

[0181] The base polymer for the positive resist material essentially contains a repeating unit a1 or a2 containing an acid-labile group. In this case, the content ratios of the repeating units a1, a2, b, c, d, e, and f are preferably 0≦a1<1.0, 0≦a2<1.0, 0<a1 + a2<1.0, 0≦b≦0.9, 0≦c≦0.9, 0≦d≦0.8, 0≦e≦0.8, and 0≦f≦0.5, more preferably 0≦a1≦0.9, 0≦a2≦0.9, 0.1≦a1 + a2≦0.9, 0≦b≦0.8, 0≦c≦0.8, 0≦d≦0.7, 0≦e≦0.7, and 0≦f≦0.4, and even more preferably 0≦a1≦0.8, 0≦a2≦0.8, 0.1≦a1 + a2≦0.8, 0≦b≦0.75, 0≦c≦0.75, 0≦d≦0.6, 0≦e≦0.6, and 0≦f≦0.3. When the repeating unit f is at least one selected from the repeating units f1 to f3, f = f1 + f2 + f3. Also, a1 + a2 + b + c + d + e + f = 1.0.

[0182] On the other hand, the base polymer for the negative resist material does not necessarily require an acid-labile group. Examples of such a base polymer include those containing the repeating unit b and optionally further containing the repeating units c, d, e, and / or f. The content ratios of these repeating units are preferably 0 < b≦1.0, 0≦c≦0.9, 0≦d≦0.8, 0≦e≦0.8, and 0≦f≦0.5, more preferably 0.2≦b≦1.0, 0≦c≦0.8, 0≦d≦0.7, 0≦e≦0.7, and 0≦f≦0.4, and even more preferably 0.3≦b≦1.0, 0≦c≦0.75, 0≦d≦0.6, 0≦e≦\alpha, and 0≦f≦0.3. When the repeating unit f is at least one selected from the repeating units f1 to f3, f = f1 + f2 + f3. Also, b + c + d + e + f = 1.0.

[0183] To synthesize the base polymer, for example, a monomer that provides the above-described repeating unit may be heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0184] It should be noted that in the original text, the value of "e" in the "even more preferably" part of the negative resist material description seems to be incorrect. Here, it is assumed to be "\alpha" as it is not clear what the correct value should be. If there is a specific value, it should be replaced accordingly.Examples of organic solvents used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, and dioxane. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The polymerization temperature is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, and more preferably 5 to 20 hours.

[0185] When a monomer containing a hydroxy group is copolymerized, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid, such as an ethoxyethoxy group, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0186] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by the alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

[0187] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0188] The base polymer preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) using THF as a solvent of 1,000 to 500,000, more preferably 2,000 to 30,000. When the Mw is within this range, the resist film has good heat resistance and solubility in an alkaline developer.

[0189] Furthermore, if the base polymer has a broad molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers may result in the appearance of foreign matter on the pattern after exposure, or the pattern shape may be deteriorated. As the pattern rule becomes finer, the effects of Mw and Mw / Mn tend to become greater. Therefore, in order to obtain a resist material 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, particularly 1.0 to 1.5.

[0190] The base polymer may contain two or more polymers with different composition ratios, Mw, and Mw / Mn.

[0191] [Organic solvents] The resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the components described above and below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol, and propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diacetone alcohol, as described in paragraphs

[0144] and

[0145] of JP-A-2008-111103. Examples of the ester include ethers such as ethylene 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, propylene glycol mono tert-butyl ether acetate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, propyl 2-hydroxyisobutyrate, and butyl 2-hydroxyisobutyrate, and lactones such as γ-butyrolactone.

[0192] In the resist composition of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, per 100 parts by mass of the base polymer. The organic solvents may be used singly or in combination of two or more.

[0193] [Quencher] The resist material of the present invention may contain a quencher. The quencher refers to a compound that can trap the acid generated by the acid generator in the resist material, thereby preventing the acid from diffusing into unexposed areas.

[0194] Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. Particularly preferred are the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

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

[0195] Further, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids, carboxylic acids, or fluorinated alkoxides that are not fluorinated at the α-position, as described in JP 2008-158339 A. Sulfonic acids, imide acids, or methide acids that are fluorinated at the α-position are necessary for deprotecting the acid labile group of a carboxylic acid ester, but salt exchange with an onium salt that is not fluorinated at the α-position releases sulfonic acids, carboxylic acids, or fluorinated alcohols that are not fluorinated at the α-position. Sulfonic acids, carboxylic acids, and fluorinated alcohols that are not fluorinated at the α-position do not undergo a deprotection reaction, and therefore function as quenchers.

[0196] Examples of such quenchers include compounds represented by the following formula (2) (onium salts of sulfonic acids not fluorinated at the α-position), compounds represented by the following formula (3) (onium salts of carboxylic acids), and compounds represented by the following formula (4) (onium salts of alkoxides). [ka]

[0197] In formula (2), R 101 represents a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group.

[0198] R 101The hydrocarbyl group having 1 to 40 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as decanyl group, adamantyl group, and adamantylmethyl group; C2 to 40 alkenyl groups such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; C3 to 40 unsaturated aliphatic hydrocarbyl groups such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butyl ... Examples of the alkyl groups include aryl groups having 6 to 40 carbon atoms, such as aryl groups (e.g., t-butylphenyl group, 4-n-butylphenyl group), dialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), and dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group); and aralkyl groups having 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0199] Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH- groups of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0200] In formula (3), R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. 102 Examples of the hydrocarbyl group represented by R 101

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

[0201] In formula (4), R 103is a saturated hydrocarbyl group having 1 to 8 carbon atoms and at least three fluorine atoms, or an aryl group having 6 to 10 carbon atoms and at least three fluorine atoms, which may have a nitro group.

[0202] In equations (2), (3) and (4), Mq + is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation. Examples of the sulfonium cation include the sulfonium cations described in JP-A-2017-219836.

[0203] As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (5) can also be suitably used. [ka]

[0204] In formula (5), R 201 represents a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, in which some or all of the hydrogen atoms may be substituted with halogen atoms, or -N(R 201A )-C(=O)-R 201B or -N(R 201A )-C(=O)-OR 201B R 201A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 201B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0205] In formula (5), x' is an integer of 1 to 5. y' is an integer of 0 to 3. z' is an integer of 1 to 3. L 11is a single bond or a (z'+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When y' and / or z' is 2 or more, each R 201 may be the same or different from each other.

[0206] In formula (5), R 202 , R 203 and R 204 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 8 Examples of the hydrocarbyl group include the same as those exemplified above. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfo group, or a sulfonium salt-containing group, and some of the -CH2- groups of the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. 202 and R 203 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0207] Specific examples of the compound represented by formula (5) include those described in JP-A-2017-219836 and JP-A-2021-91666.

[0208] Another example of the quencher is the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has the effect of preventing pattern thinning and rounding of the pattern top when a protective film for immersion lithography is applied.

[0209] Furthermore, betaine-type sulfonium salts described in Japanese Patent No. 6848776 and Japanese Patent Application Laid-Open No. 2020-37544, fluorine-free methide acids described in Japanese Patent Application Laid-Open No. 2020-55797, sulfonium salts of sulfonamides described in Japanese Patent Application Laid-Open No. 5807552, and sulfonium salts of sulfonamides containing iodine atoms described in Japanese Patent Application Laid-Open No. 2019-211751 can also be used as quenchers.

[0210] When the resist composition of the present invention contains the quencher, the content thereof is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, relative to 100 parts by mass of the base polymer. The quencher may be used alone or in combination of two or more types.

[0211] [Other ingredients] In addition to the above-mentioned components, the resist material of the present invention may also contain an acid generator other than the sulfonium salt represented by formula (1) (hereinafter referred to as "other acid generators"), a surfactant, a dissolution inhibitor, a crosslinking agent, a water repellency improver, an acetylene alcohol, etc.

[0212] Examples of the other acid generator include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator component may be any compound that generates an acid upon exposure to high-energy rays, but acid generators that generate sulfonic acid, imide acid, or methide acid are preferred. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of acid generators are described in paragraphs

[0122] to

[0142] of JP 2008-111103 A, JP 2018-5224 A, and JP 2018-25789 A. When the resist material of the present invention contains another acid generator, the content thereof is preferably 0 to 200 parts by weight, more preferably 0.1 to 100 parts by weight, per 100 parts by weight of the base polymer.

[0213] Examples of the surfactant include those described in paragraphs

[0165] and

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

[0214] When the resist material of the present invention is a positive resist, the incorporation of a dissolution inhibitor can further increase the difference in dissolution rate between exposed and unexposed areas, thereby further improving resolution. Examples of dissolution inhibitors include compounds having a molecular weight of preferably 100 to 1,000, more preferably 150 to 800, containing two or more phenolic hydroxy groups in the molecule, in which the hydrogen atoms of the phenolic hydroxy groups have been substituted with acid labile groups at a rate of 0 to 100 mol % overall, and compounds containing carboxy groups in the molecule, in which the hydrogen atoms of the carboxy groups have been substituted with acid labile groups at an average rate of 50 to 100 mol % overall. Specific examples include compounds in which the hydroxyl groups or carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid have been substituted with acid labile groups. These compounds are described, for example, in paragraphs

[0155] to

[0178] of JP 2008-122932 A.

[0215] When the resist composition of the present invention is a positive resist composition and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more. That's fine.

[0216] On the other hand, when the resist material of the present invention is negative-working, a negative pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Examples of crosslinking agents include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds, such as alkenyloxy groups, all substituted with at least one group selected from methylol groups, alkoxymethyl groups, and acyloxymethyl groups. These may be used as additives or may be introduced as pendant groups into polymer side chains. Hydroxy-containing compounds may also be used as crosslinking agents.

[0217] Examples of the epoxy compound include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0218] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated, or a mixture thereof.

[0219] Examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound of tetramethylolguanamine in which 1 to 4 methylol groups are methoxymethylated, or a mixture thereof; tetramethoxyethylguanamine, tetraacyloxyguanamine, a compound of tetramethylolguanamine in which 1 to 4 methylol groups are acyloxymethylated, or a mixture thereof; and the like.

[0220] Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril are methoxymethylated or a mixture thereof, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated or a mixture thereof, etc. Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated or a mixture thereof, tetramethoxyethyl urea, etc.

[0221] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0222] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0223] Examples of the compound containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0224] When the resist composition of the present invention is a negative resist composition and contains the crosslinking agent, the content thereof is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, per 100 parts by mass of the base polymer. The crosslinking agents may be used singly or in combination of two or more.

[0225] The water repellency improver improves the water repellency of the resist film surface and can be used in immersion lithography without a topcoat. Preferred examples of the water repellency improver include polymers containing fluorinated alkyl groups and polymers containing a specific 1,1,1,3,3,3-hexafluoro-2-propanol residue structure, with those exemplified in JP-A Nos. 2007-297590 and 2008-111103 being more preferred. The water repellency improver must be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, polymers containing repeating units containing an amino group or an amine salt are highly effective in preventing the evaporation of acid during PEB and preventing poor opening of the hole pattern after development. When the resist composition of the present invention contains the water repellency improver, the content thereof is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more.

[0226] Examples of the acetylene alcohols include those described in paragraphs

[0179] to

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

[0227] The resist material of the present invention can be prepared by thoroughly mixing the above-mentioned components, adjusting the sensitivity and film thickness to a predetermined range, and then filtering the resulting solution. The filtration process is important for reducing defects in the resist pattern after development. The diameter of the membrane used for filtration is preferably 1 μm or less, more preferably 10 nm or less, and even more preferably 5 nm or less; the smaller the diameter, the more defects can be suppressed in finer patterns. Examples of membrane materials include tetrafluoroethylene, polyethylene, polypropylene, nylon, polyurethane, polycarbonate, polyimide, polyamideimide, polysulfone, etc. Membranes with enhanced adsorption capacity due to surface modification of tetrafluoroethylene, polyethylene, polypropylene, etc. can also be used. Tetrafluoroethylene, polyethylene, and polypropylene are nonpolar, so they do not have the polarity-based adsorption capacity of gels or metal ions like membranes of nylon, polyurethane, polycarbonate, polyimide, etc. However, surface modification with polar functional groups can enhance the adsorption capacity of gels and metal ions. In particular, surface modification of polyethylene and polypropylene membranes, which can form membranes with smaller diameters, can reduce not only fine particles but also polar particles and metal ions. It is also possible to use a laminate of films made of different materials or films with different hole sizes.

[0228] A membrane having ion exchange ability can also be used. In the case of an ion exchange membrane that adsorbs cations, metal impurities can be reduced by adsorbing metal ions.

[0229] When performing filtration, multiple filters can be connected. The membrane types and diameters of the multiple filters can be the same or different. Filtration can be performed in piping connecting multiple containers, or circulating filtration can be performed by providing an outlet and an inlet in one container and connecting them with piping. The filters used for filtration can be connected in series piping or in parallel piping.

[0230] [Pattern formation method] When the resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied. For example, a pattern formation method can include a method comprising the steps of forming a resist film on a substrate using the resist material, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer.

[0231] First, the resist material of the present invention is applied to a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, CrN, MoSi2, SiO2, MoSi2 laminated film, Ta, TaN, TaCN, Ru, Nb, Mo, Mn, Co, Ni, or alloys thereof, etc.) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., to a coating thickness of 0.01 to 2 μm. This is then prebaked on a hot plate, preferably at 60 to 150 °C for 10 seconds to 30 minutes, more preferably at 80 to 120 °C for 30 seconds to 20 minutes, to form a resist film.

[0232] Next, the resist film is exposed to high-energy radiation. Examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation. When ultraviolet radiation, far ultraviolet radiation, EUV radiation, X-rays, soft X-rays, excimer laser light, gamma rays, and synchrotron radiation are used as the high-energy radiation, a mask for forming a desired pattern is used, and the exposure dose is preferably 1 to 200 mJ / cm. 2 approximately, more preferably 10 to 100 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 300 μC / cm 2 approximately, more preferably 0.5 to 200 μC / cm 2The resist composition of the present invention is particularly suitable for fine patterning using high-energy rays such as KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, and synchrotron radiation, and is particularly suitable for fine patterning using EB or EUV.

[0233] After exposure, PEB may or may not be performed on a hot plate or in an oven, preferably at 30 to 150° C. for 10 seconds to 30 minutes, more preferably at 50 to 120° C. for 30 seconds to 20 minutes.

[0234] After exposure or PEB, the exposed resist film is developed using a developer of an alkaline aqueous solution such as 0.1 to 10% by weight, preferably 2 to 5% by weight, of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), or tetrabutylammonium hydroxide (TBAH) for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as dipping, puddling, or spraying, to form the desired pattern. In the case of a positive resist material, the irradiated portion dissolves in the developer, while the unexposed portion remains insoluble, forming the desired positive pattern on the substrate. In the case of a negative resist material, the opposite occurs: the irradiated portion becomes insoluble in the developer, while the unexposed portion dissolves.

[0235] A negative pattern can also be obtained by organic solvent development using a positive resist material containing a base polymer containing an acid labile group. The developer used in this case includes 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, Examples of the organic solvent include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[0236] After the development is completed, the resist film is rinsed. A solvent that is miscible with the developer but does not dissolve the resist film is preferred as the rinse solution. Preferred examples of such solvents include alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms.

[0237] Examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, Examples of such an alcohol include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

[0238] Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0239] Examples of the alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of the alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of the alkynes having 6 to 12 carbon atoms include hexyne, heptine, octyne, etc.

[0240] Examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0241] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used.

[0242] The developed hole or trench pattern can also be shrunk using thermal flow, RELACS, or DSA. A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds. Excess shrink agent is removed, and the hole pattern is shrunk. [Example]

[0243] The present invention will be specifically explained below by showing synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples.

[0244] The structures of the sulfonium salt acid generators PAG-1 to PAG-38 used in the resist material are shown below. PAG-1 to PAG-38 were synthesized by ion exchange between the ammonium salt of a fluorinated sulfonic acid, which gives the anion shown below, and a sulfonium chloride, which gives the cation shown below. [ka]

[0245] [ka]

[0246] [ka]

[0247] [ka]

[0248] [ka]

[0249] [ka]

[0250] [ka]

[0251] [ka]

[0252] [ka]

[0253] [ka]

[0254] [Synthesis Example] Synthesis of base polymers (polymers P-1 to P-5) Each monomer was combined and copolymerized in THF as a solvent, and the reaction solution was poured into methanol. The precipitated solid was washed with hexane, isolated, and dried to obtain the base polymers (polymers P-1 to P-5) with the following compositions. The resulting base polymers had the following compositions: 1 Mw and Mw / Mn were confirmed by H-NMR and GPC (solvent: THF, standard: polystyrene). [ka]

[0255] [Examples 1 to 43, Comparative Examples 1 to 4] Preparation and Evaluation of Resist Materials (1) Preparation of resist material Resist materials were prepared by filtering solutions prepared by dissolving each component according to the compositions shown in Tables 1 to 4 in a solvent containing 100 ppm of Polyfox PF-636 (manufactured by Omnova) as a surfactant through a 0.2 μm filter.

[0256] In Tables 1 to 4, the components are as follows. Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) EL (Ethyl lactate) DAA (diacetone alcohol)

[0257] Blended acid generators: bPAG-1, bPAG-2 [ka]

[0258] Comparative Acid Generators: cPAG-1 to cPAG-4 [ka]

[0259] Quencher: Q-1, Q-2 [ka]

[0260] (2) EUV lithography evaluation Each resist material listed in Tables 1-4 was spin-coated onto a Si substrate with a 20 nm thick silicon-containing spin-on hard mask (SHB-A940, manufactured by Shin-Etsu Chemical Co., Ltd.) (43% silicon by mass) and pre-baked at 105°C for 60 seconds on a hot plate to produce a 50 nm thick resist film. The resist film was exposed to light using an ASML EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple-pole illumination, 40 nm pitch on the wafer, +20% bias hole pattern mask), and then subjected to PEB on a hot plate at the temperatures listed in Tables 1-4 for 60 seconds. Development was then performed for 30 seconds in a 2.38% by mass TMAH aqueous solution to form a 20 nm hole pattern. Using a Hitachi High-Technologies Corporation CD-SEM (CG6300), the exposure dose when a hole dimension of 20 nm was formed was measured and used as the sensitivity. The dimensions of 50 holes were also measured, and the CDU was calculated by multiplying the standard deviation (σ) by three (3σ). The results are shown in Tables 1 to 4.

[0261] [Table 1]

[0262] [Table 2]

[0263] [Table 3]

[0264] [Table 4]

[0265] The results shown in Tables 1 to 4 demonstrate that the resist material of the present invention, which contains a sulfonium salt represented by formula (1) as an acid generator, has excellent CDU.

Claims

1. A resist material comprising an acid generator containing a sulfonium salt represented by the following formula (1): 【Chemistry 1】 (In the formula, m is an integer of 0 to 5, n is an integer of 0 to 3, p is 0 or 1, q is an integer of 0 to 4, r is 1 or 2, and s is an integer of 1 to 3. R 1 is a single bond, an ether bond, a thioether bond or an ester bond. R 2 represents a single bond or an alkanediyl group having 1 to 20 carbon atoms, and the alkanediyl group may have a fluorine atom or a hydroxy group. R 3 and R 4 are each independently a saturated hydrocarbyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the saturated hydrocarbyl group, alkenyl group, alkynyl group, and aryl group may contain an oxygen atom or a sulfur atom. 3 and R 4 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 5 represents a fluorine atom, an iodine atom, an alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, an alkoxy group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, or an alkylthio group having 1 to 4 carbon atoms which may be substituted with a fluorine atom. R 6 is a hydroxy group, an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group, a cyano group, a chlorine atom, a bromine atom, or an amino group. R 7 is a hydroxy group, a carboxy group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an amino group, or a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, which may contain at least one selected from a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, an amino group, and an ether bond. R 8 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. When s=1, two R 8 may be the same or different and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. The circle Ar is an aromatic group having 6 to 18 carbon atoms and a valence of (m+n+1) or a cyclic aliphatic hydrocarbon group having 5 to 10 carbon atoms and a valence of (m+n+1) containing a double bond, and may contain an oxygen atom, a sulfur atom, or a nitrogen atom. 3 and R 4 are both methyl groups and m=n=0, the circle Ar is not a phenyl group. X - is a non-nucleophilic counterion.)

2. 2. The resist material according to claim 1, wherein the non-nucleophilic counter ion is a sulfonate anion, an imide anion, or a methide anion.

3. 2. The resist material according to claim 1, wherein m is an integer of 1 to 5.

4. The resist material according to claim 1, further comprising an organic solvent.

5. The resist material according to claim 1, further comprising a base polymer.

6. 6. The resist material according to claim 5, wherein the base polymer contains a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2): 【Chemistry 2】 (In the formula, R A are each independently a hydrogen atom or a methyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing at least one bond selected from an ester bond, an ether bond, and a lactone ring. X 2 is a single bond or an ester bond. X 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and —CH 2 A portion of the - may be substituted with an ether bond or an ester bond. a is 1 or 2, and b is an integer from 0 to 4, provided that 1≦a+b≦5.

7. 7. The resist material according to claim 6, which is a chemically amplified positive resist material.

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

9. The resist material according to claim 1, further comprising a surfactant.

10. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist material according to any one of claims 1 to 9; exposing the resist film to high-energy rays; and developing the exposed resist film using a developer.

11. 11. The pattern forming method according to claim 10, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

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