Resist composition and resist film forming method using same

Abstract

The present invention provides a resist composition which contains a resin (A) and a solvent (B) containing a compound (B1) represented by general formula (b-1), and which contains an active ingredient in an amount of 45 mass% or less with respect to the total amount of the resist composition. [In formula (b-1), R1 represents an alkyl group having 1-10 carbon atoms.]

Description

Resist composition and method for forming a resist film using the same

[0001] The present invention relates to a resist composition and a method of forming a resist film using the resist composition.

[0002] In the manufacture of semiconductor devices and liquid crystal devices, microfabrication is performed by lithography using photoresist materials. In particular, in the manufacture of semiconductor devices, the recent trend toward higher integration and higher speed of LSIs has led to a demand for even finer pattern dimensions. To accommodate such demand for finer pattern dimensions, the wavelength of the lithography light source used in resist pattern formation has been shortened from KrF excimer lasers (248 nm) to ArF excimer lasers (193 nm). For example, Patent Document 1 discloses an invention relating to a positive resist composition, as a photoresist material suitable for resist pattern formation using an ArF excimer laser, that uses a resin in which the hydroxyl group in the carboxyl group of (meth)acrylic acid is protected with an acid-dissociable, dissolution-inhibiting group.

[0003] In recent years, in addition to miniaturization of pattern dimensions, development of three-dimensional structure devices has been progressing, which aims to increase memory capacity by stacking cells. In the manufacture of three-dimensional structure devices, resist patterns are formed after depositing thick resist films with a thickness greater than that of conventional devices.

[0004] Japanese Patent Application Laid-Open No. 2003-241385

[0005] As described above, the photoresist materials used in manufacturing various devices such as semiconductor elements and liquid crystal elements are required to have different properties depending on the type of device, and therefore there is a demand for photoresist materials that can form resist films suitable for manufacturing various devices.

[0006] The present invention provides a resist composition that contains a resin and a solvent containing a compound having a specific structure, and in which the content of an active ingredient is limited to a predetermined value or less, and a method of forming a resist film using the resist composition. That is, the present invention provides the following [1] to

[14] . [1] A resist composition that contains a resin (A) and a solvent (B) that contains a compound (B1) represented by the following general formula (b-1), wherein the content of the active ingredient is 45 mass% or less based on the total amount of the resist composition: [In the above formula (b-1), R １ is an alkyl group having 1 to 10 carbon atoms.] [2] The resist composition according to the above [1], further comprising at least one additive (C) selected from a photosensitizer and an acid generator. [3] R in the general formula (b-1) １ [4] The resist composition according to the above [1] or [2], wherein R in the general formula (b-1) is a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, or a t-butyl group. １is an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, or a t-butyl group. [5] The resist composition according to any one of [1] to [4] above, wherein the solvent (B) includes a solvent (B2) other than the compound (B1). [6] The resist composition according to [5] above, wherein the solvent (B) includes, as the solvent (B2), one or more selected from the group consisting of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, and methyl 3-hydroxyisobutyrate. [7] The resist composition according to [5] above, wherein the solvent (B) includes, as the solvent (B2), one or more selected from the group consisting of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, methyl 3-hydroxyisobutyrate, and 1-methoxy-2-propanol. [8] The resist composition according to any one of [5] to [7] above, wherein the solvent (B2) accounts for 100% by mass or less of the total amount (100% by mass) of the compound (B1). [9] The resist composition according to [8] above, wherein the solvent (B2) accounts for less than 70% by mass of the total amount (100% by mass) of the compound (B1).

[10] The resist composition according to [8] or [9] above, wherein the solvent (B2) accounts for 0.0001% by mass or more of the total amount (100% by mass) of the compound (B1).

[11] The resist composition according to any one of [5] to

[10] above, wherein the solvent (B2) accounts for less than 100% by mass of the total amount (100% by mass) of the resist composition.

[12] The resist composition according to any one of [1] to

[11] above, wherein the resin (A) comprises a novolac resin (A1).

[13] The resist composition according to any one of [1] to

[11] above, wherein the resin (A) comprises a resin (A2) having at least one of a structural unit (a2-1) derived from a phenolic hydroxyl group-containing compound and a structural unit (a2-2) that can be decomposed by the action of an acid, a base, or heat to form an acidic functional group.

[14] The resist composition according to any one of [1] to

[11] above, wherein the resin (A) comprises a resin (A3) having a structural unit (a3-1) that has an adamantane structure.

[15] The resist composition according to

[14] above, wherein the resin (A3) is a copolymer having a structural unit (a3-1) and a structural unit (a3-2) having a lactone structure.

[16] The resist composition according to

[14] or

[15] above, wherein the content of the structural unit (a3-1α) having an adamantane structure substituted with a hydroxy group is less than 50 mol% relative to the total amount of structural units in the resin (A3).

[17] The resist composition according to any one of [1] to

[11] above, wherein the resin (A) comprises a resin (A4) having two or more structural units selected from the group consisting of a structural unit (a2-1) derived from a phenolic hydroxyl group-containing compound, a structural unit (a2-2) that can decompose under the action of an acid, a base, or heat to form an acidic functional group, a structural unit (a3-1) having an adamantane structure, and a structural unit (a3-2) having a lactone structure.

[18] A method for forming a resist film, comprising: step (1): applying the resist composition according to any one of the above items [1] to

[17] onto a substrate to form a coating film; step (2): performing a heat treatment after step (1); and step (3): forming a resist pattern.

[0007] A resist composition according to a preferred embodiment of the present invention is capable of forming a resist film suitable for the production of various devices, even though the content of active ingredients, including resin, is limited to a specified value or less.

[0008] [Resist Composition] The resist composition of the present invention contains a resin (A) (hereinafter also referred to as "component (A)") and a solvent (B) (hereinafter also referred to as "component (B)") that contains a compound (B1) represented by general formula (b-1). The resist composition of the present invention is used to form a resist film, but the term "resist film" does not include films used as underlayers of a resist (for example, resist auxiliary films such as a resist middle layer film or a resist underlayer film). Furthermore, the resist composition of one embodiment of the present invention preferably further contains at least one additive (C) (hereinafter also referred to as "component (C)") selected from a photosensitizer and an acid generator. Furthermore, in the resist composition of the present invention, the content of the active component is limited to 45% by mass or less, based on the total amount (100% by mass) of the resist composition. In this specification, the term "active component" refers to all components contained in the resist composition, excluding component (B). Specifically, these include the resin (A) and additive (C), as well as other additives described below, such as acid crosslinkers, acid diffusion controllers, dissolution promoters, dissolution control agents, sensitizers, surfactants, organic carboxylic acids or phosphorus oxoacids or derivatives thereof, dyes, pigments, adhesion aids, antihalation agents, storage stabilizers, antifoaming agents, and shape improvers. Generally, for example, to manufacture a three-dimensional structure device, it is necessary to form a thick resist film. However, when a resist composition with a low resin content is used, forming a thick resist film becomes difficult. In contrast, by using a compound represented by general formula (b-1) as a solvent, the resist composition of the present invention can become a photoresist material capable of forming a thick resist film even when the content of active ingredients, including the resin, is reduced to 45% by mass or less. Furthermore, since the resist composition of the present invention has a reduced content of active ingredients of 45% by mass or less, it is also advantageous from an economical standpoint.

[0009] In the resist composition of one embodiment of the present invention, the content of the active ingredient may be set appropriately depending on the application, such as 42% by mass or less, 40% by mass or less, 36% by mass or less, 31% by mass or less, 26% by mass or less, 23% by mass or less, 20% by mass or less, 18% by mass or less, 16% by mass or less, 12% by mass or less, 10% by mass or less, 6% by mass or less, or 3% by mass or less, relative to the total amount (100% by mass) of the resist composition. Meanwhile, the lower limit of the content of the active ingredient is also set appropriately depending on the application, and may be 1% by mass or more, 2% by mass or more, 4% by mass or more, 7% by mass or more, or 10% by mass or more, relative to the total amount (100% by mass) of the resist composition. The content of the active ingredient can be determined in any combination by appropriately selecting from the above-mentioned upper and lower limit values.

[0010] In a resist composition according to one embodiment of the present invention, from the viewpoint of providing a photoresist material capable of forming a thick resist film, the content of component (A) among the active components is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, still more preferably 75 to 100 mass%, and particularly preferably 80 to 100 mass%, relative to the total amount (100 mass%) of active components contained in the resist composition.

[0011] The resist composition of one embodiment of the present invention may contain components other than the above components (A) to (C), depending on the application. However, in the resist composition of one embodiment of the present invention, the total content of components (A), (B), and (C) is preferably 30 to 100 mass%, more preferably 40 to 100 mass%, even more preferably 60 to 100 mass%, still more preferably 80 to 100 mass%, and particularly preferably 90 to 100 mass%, based on the total amount (100 mass%) of the resist composition. Below, the details of each component contained in the resist composition of one embodiment of the present invention are described.

[0012] <Component (A): Resin> The resin (A) contained in the resist composition of one embodiment of the present invention is not particularly limited, and known resins for photoresists such as those for g-line, i-line, KrF excimer laser, ArF excimer laser, EUV, and EB can be used, and the resin can be appropriately selected depending on the application. In this specification, the term "resin" refers not only to a polymer having a predetermined structural unit, but also to a compound having a predetermined structure. The weight average molecular weight (Mw) of the resin used in one embodiment of the present invention is preferably 400 to 50,000, more preferably 1,000 to 40,000, and even more preferably 1,000 to 30,000.

[0013] In the resist composition of the present invention, the content of component (A) may be set appropriately depending on the application, based on the total amount (100 mass%) of the resist composition, such as 45 mass% or less, 42 mass% or less, 40 mass% or less, 35 mass% or less, 31 mass% or less, 26 mass% or less, 23 mass% or less, 20 mass% or less, 18 mass% or less, 16 mass% or less, 12 mass% or less, 10 mass% or less, 6 mass% or less, or 3 mass% or less. The lower limit of the content of component (A) is also set appropriately depending on the application, and may be 1 mass% or more, 2 mass% or more, 4 mass% or more, 7 mass% or more, or 10 mass% or more based on the total amount (100 mass%) of the resist composition. The content of component (A) can be specified in any combination by appropriately selecting from the above-mentioned upper and lower limit values.

[0014] For example, when used as a photoresist material for producing a liquid crystal element for exposure to ultraviolet light such as g-line or i-line, the resin (A) preferably contains a novolac resin (A1). Furthermore, when used as a photoresist material for KrF excimer lasers, the resin (A) preferably contains a resin (A2) having at least one of a structural unit derived from a phenolic hydroxyl group-containing compound and a structural unit that can be decomposed by the action of an acid, a base, or heat to form an acidic functional group. Furthermore, when used as a photoresist material for ArF excimer lasers, the resin (A) preferably contains a resin (A3) having a structural unit with an adamantane structure. When used as a photoresist material for EUV, the resin (A) preferably contains a resin (A4) (excluding resins (A2) and (A3)) having two or more structural units selected from a structural unit derived from a phenolic hydroxyl group-containing compound, a structural unit that can be decomposed by the action of an acid, a base, or heat to form an acidic functional group, a structural unit with an adamantane structure, and a structural unit with a lactone structure.

[0015] The resin (A) contained in the resist composition of one embodiment of the present invention may contain only one selected from the resins (A1), (A2), (A3), and (A4), or may contain a combination of two or more selected from these resins. Furthermore, the resin (A) may contain resins other than the resins (A1), (A2), (A3), and (A4). However, the total content of the resins (A1), (A2), (A3), and (A4) in the resin (A) used in one embodiment of the present invention is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass, based on the total amount (100% by mass) of the resin (A). These resins (A1), (A2), (A3), and (A4) are described below.

[0016] [Novolac Resin (A1)] Examples of the novolac resin (A1) used in one embodiment of the present invention include resins obtained by reacting a phenol with at least one of an aldehyde and a ketone in the presence of an acid catalyst (e.g., hydrochloric acid, sulfuric acid, oxalic acid, etc.). The novolac resin (A1) is not particularly limited, and known resins can be used, such as those described in JP-A No. 2009-173623, WO 2013-024778, and WO 2015-137485.

[0017] Examples of phenols include phenol, ortho-cresol, meta-cresol, para-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methyl Examples of the phenols include luresorcinol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, thymol, isothymol, 4,4'-biphenol, 1-naphthol, 2-naphthol, hydroxyanthracene, hydroxypyrene, 2,6-dihydroxynaphthalene, and 2,6-dihydroxynaphthalene. These phenols may be used alone or in combination of two or more.

[0018] Examples of aldehydes include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropionaldehyde, β-phenylpropionaldehyde, benzaldehyde, 4-biphenylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, Examples of the aldehydes and ketones include o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, 3,4-dimethylbenzaldehyde, p-n-propylbenzaldehyde, p-n-butylbenzaldehyde, terephthalaldehyde, 1-naphthaldehyde, and 2-naphthaldehyde. Examples of the ketones include acetone, methyl ethyl ketone, diethyl ketone, acetophenone, and diphenyl ketone. These aldehydes and ketones may be used alone or in combination of two or more.

[0019] Among these, the novolak resin (A1) used in one embodiment of the present invention is preferably a resin obtained by condensation reaction of cresol with an aldehyde, more preferably a resin obtained by condensation reaction of at least one of metacresol and para-cresol with at least one of formaldehyde and paraformaldehyde, and even more preferably a resin obtained by using metacresol and para-cresol in combination and condensing these with at least one of formaldehyde and paraformaldehyde. When metacresol and para-cresol are used in combination, the blending ratio of the raw materials metacresol and para-cresol [metacresol / para-cresol] is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 80 / 20, and even more preferably 50 / 50 to 70 / 30 by mass.

[0020] The novolac resin (A1) used in one embodiment of the present invention may be a commercially available product such as "EP4080G" or "EP4050G" (both cresol novolac resins manufactured by Asahi Organic Chemicals Co., Ltd.).

[0021] The weight average molecular weight (Mw) of the novolak resin (A1) used in one embodiment of the present invention is preferably 500 to 30,000, more preferably 1,000 to 20,000, even more preferably 1,000 to 15,000, and still more preferably 1,000 to 10,000.

[0022] [Resin (A2)] The resin (A2) used in one embodiment of the present invention is not particularly limited, and known resins can be used, but it is preferably a resin that has at least one of a structural unit (a2-1) derived from a phenolic hydroxyl group-containing compound and a structural unit (a2-2) that can decompose under the action of an acid, a base, or heat to form an acidic functional group. A copolymer that has both the structural unit (a2-1) and the structural unit (a2-2) is more preferable. A resin that has at least one of the structural unit (a2-1) and the structural unit (a2-2) can increase the solubility in an alkaline developer.

[0023] In the resin (A2) used in one embodiment of the present invention, the combined amount of the structural units (a2-1) and (a2-2) relative to the total amount (100 mol%) of structural units in the resin (A2) is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, still more preferably 70 mol% or more, and particularly preferably 80 mol% or more.

[0024] Furthermore, when the resin (A2) used in one embodiment of the present invention is a copolymer containing both the structural unit (a2-1) and the structural unit (a2-2), the content ratio of the structural unit (a2-1) to the structural unit (a2-2) [(a2-1) / (a2-2)], expressed as a molar ratio, is preferably 1 / 10 to 10 / 1, more preferably 1 / 5 to 8 / 1, even more preferably 1 / 2 to 6 / 1, and still more preferably 1 / 1 to 4 / 1.

[0025] Examples of the phenolic hydroxyl group-containing compound that constitutes the structural unit (a2-1) include hydroxystyrenes (o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene) and isopropenylphenols (o-isopropenylphenol, m-isopropenylphenol, p-isopropenylphenol), with hydroxystyrene being preferred.

[0026] Examples of acidic functional groups that can be formed by decomposition of the structural unit (a2-2) by the action of an acid, a base, or heat include a phenolic hydroxyl group and a carboxyl group. Examples of monomers that can form a phenolic hydroxyl group include hydroxy(α-methyl)styrenes protected with an acetal group, such as p-(1-methoxyethoxy)styrene, p-(1-ethoxyethoxy)styrene, p-(1-n-propoxyethoxy)styrene, p-(1-i-propoxyethoxy)styrene, p-(1-cyclohexyloxyethoxy)styrene, and α-methyl-substituted derivatives thereof; p-acetoxystyrene, t-butoxycarbonylstyrene, t-butoxystyrene, and α-methyl-substituted derivatives thereof. These may be used alone, or two or more types may be used in combination.

[0027] Furthermore, examples of monomers of structural units capable of forming a carboxyl group include (meth)acrylates protected with an acid-decomposable ester group, such as t-butyl(meth)acrylate, tetrahydropyranyl(meth)acrylate, 2-methoxybutyl(meth)acrylate, 2-ethoxyethyl(meth)acrylate, 2-t-butoxycarbonylethyl(meth)acrylate, 2-benzyloxycarbonylethyl(meth)acrylate, 2-phenoxycarbonylethyl(meth)acrylate, 2-cyclohexyloxycarbonyl(meth)acrylate, 2-isobornyloxycarbonylethyl(meth)acrylate, and 2-tricyclodecanyloxycarbonylethyl(meth)acrylate. These may be used alone, or two or more types may be used in combination.

[0028] Of these, the monomer that constitutes the structural unit (a2-2) is preferably at least one selected from the group consisting of t-butyl(meth)acrylate, tetrahydropyranyl(meth)acrylate, 2-cyclohexyloxycarbonylethyl(meth)acrylate, and p-(1-ethoxyethoxy)styrene.

[0029] As described above, the resin (A2) used in one embodiment of the present invention may be a resin that contains at least one of the structural unit (a2-1) and the structural unit (a2-2), but may also contain structural units other than these. Examples of monomers that constitute such other structural units include alkyl(meth)acrylates; hydroxy group-containing monomers; epoxy group-containing monomers; alicyclic structure-containing monomers; olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene, and chloroprene; aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and p-methoxystyrene; cyano group-containing vinyl monomers such as (meth)acrylonitrile and vinylidene cyanide; (meth)acrylamides such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-dimethylol(meth)acrylamide; and heteroatom-containing alicyclic vinyl monomers such as (meth)acryloylmorpholine, N-vinylpyrrolidone, and N-vinylcaprolactam.

[0030] Examples of the alkyl(meth)acrylate include compounds other than the monomer that constitutes the structural unit (a2-2), such as methyl(meth)acrylate, ethyl(meth)acrylate, and propyl(meth)acrylate (n-propyl(meth)acrylate, i-propyl(meth)acrylate).

[0031] Examples of the hydroxy-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The number of carbon atoms in the alkyl group of the hydroxyalkyl (meth)acrylate is preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 6, and still more preferably 2 to 4, and the alkyl group may be a linear alkyl group or a branched alkyl group.

[0032] Examples of the epoxy-containing monomer include epoxy group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate, and 3-epoxycyclo-2-hydroxypropyl (meth)acrylate; glycidyl crotonate, and allyl glycidyl ether.

[0033] Examples of the alicyclic structure-containing monomer include cycloalkyl (meth)acrylates such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; isobornyl (meth)acrylate; and dicyclopentenyl (meth)acrylate.

[0034] The resin (A2) used in one embodiment of the present invention may be a resin having a structural unit derived from adamantyl (meth)acrylate as a structural unit derived from an alicyclic structure-containing monomer. This resin corresponds to the resin (A2) and also corresponds to the resin (A3) described below.

[0035] Furthermore, the resin (A2) used in one embodiment of the present invention may contain a structural unit derived from a monomer selected from the group consisting of esters of a compound having two or more hydroxyl groups in the molecule, such as a dihydric or higher polyhydric alcohol, a polyether diol, or a polyester diol, with (meth)acrylic acid, adducts of a compound having two or more epoxy groups in the molecule, such as an epoxy resin, with (meth)acrylic acid, and condensates of a compound having two or more amino groups in the molecule with (meth)acrylic acid. Examples of such monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, butanediol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and the like. acrylate, pentaerythritol tetra(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, N,N'-methylenebis(meth)acrylamide, (poly)alkylene glycol (derivative) di(meth)acrylates such as di(meth)acrylate of an ethylene glycol adduct or propyl glycol adduct of bisphenol A, and epoxy (meth)acrylates such as a (meth)acrylic acid adduct of bisphenol A diglycidyl ether.

[0036] The weight average molecular weight (Mw) of the resin (A2) used in one embodiment of the present invention is preferably 400 to 50,000, more preferably 1,000 to 40,000, even more preferably 1,000 to 30,000, and still more preferably 1,000 to 25,000.

[0037] [Resin (A3)] The resin (A3) used in one embodiment of the present invention is not particularly limited, and a known resin can be used, and a resin having a structural unit (a3-1) having an adamantane structure is preferably used, but the structural unit is preferably one that can be decomposed by the action of an acid to form an acidic functional group. Furthermore, from the viewpoints of solubility in solvents and adhesion to substrates, it is practically preferable for the resin (A3) to be a copolymer having a structural unit (a3-2) having a lactone structure in addition to the structural unit (a3-1).

[0038] At least one of the hydrogen atoms bonded to a carbon atom that constitutes the adamantane structure of the structural unit (a3-1) may be substituted with a substituent R. Similarly, at least one of the hydrogen atoms bonded to a carbon atom that constitutes the lactone structure of the structural unit (a3-2) may also be substituted with a substituent R. Examples of the substituent R include alkyl groups having 1 to 6 carbon atoms, hydroxyalkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 6 carbon atoms, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), deuterium atoms, hydroxy groups, amino groups, nitro groups, cyano groups, and groups represented by the following formula (i) or (ii):

[0039]

[0040] In the above formula (i) or (ii), R ａ and R ｂ are each independently an alkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. m is an integer of 1 to 10, preferably an integer of 1 to 6, more preferably an integer of 1 to 3, and even more preferably an integer of 1 or 2. A is an alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 3 carbon atoms). Examples of the alkylene group include a methylene group, an ethylene group, an n-propylene group, an i-propylene group, a 1,4-butylene group, a 1,3-butylene group, a tetramethylene group, a 1,5-pentylene group, a 1,4-pentylene group, and a 1,3-pentylene group.

[0041] In the resin (A3) used in one embodiment of the present invention, the content of the structural unit (a3-1), that is, the structural unit (a3-1α) having an adamantane structure substituted with a hydroxy group, relative to the total amount (100 mol%) of structural units in the resin (A3) is preferably less than 50 mol%, more preferably less than 44 mol%, even more preferably less than 39 mol%, and still more preferably less than 34 mol%.

[0042] In one embodiment of the present invention, the structural unit (a3-1) is preferably a structural unit (a3-1-1) represented by the following formula (a3-1-i) or a structural unit (a3-1-2) represented by the following formula (a3-1-ii).

[0043]

[0044] In the above formula, n is each independently an integer of 0 to 14, preferably an integer of 0 to 4, more preferably an integer of 0 to 2, and even more preferably an integer of 0 to 1. ｘ are each independently a hydrogen atom or a methyl group. R is each independently a substituent R that the adamantane structure may have, and is specifically as described above, but is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. X １ are each independently a single bond, an alkylene group having 1 to 6 carbon atoms, or a divalent linking group represented by any of the following formulas:

[0045] In the above formula, *1 indicates the bonding position to the oxygen atom in the above formula (a3-1-i) or (a3-1-ii), and *2 indicates the bonding position to the carbon atom of the adamantane structure. １ represents an alkylene group having 1 to 6 carbon atoms.

[0046] In one embodiment of the present invention, the structural unit (a3-2) is preferably any one of the structural unit (a3-2-1) represented by the following formula (a3-2-i), the structural unit (a3-2-2) represented by the following formula (a3-2-ii), and the structural unit (a3-2-3) represented by the following formula (a3-2-iii):

[0047]

[0048] In the above formula, n1 is an integer of 0 to 5, preferably an integer of 0 to 2, more preferably an integer of 0 to 1. n2 is an integer of 0 to 9, preferably an integer of 0 to 2, more preferably an integer of 0 to 1. n3 is an integer of 0 to 9, preferably an integer of 0 to 2, more preferably an integer of 0 to 1. R ｙ is a hydrogen atom or a methyl group. Each R is independently a substituent R that the lactone structure may have, and is specifically as described above, but is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. When there are multiple Rs, the multiple Rs may be the same group or different groups. X ２ is a single bond, an alkylene group having 1 to 6 carbon atoms, or a divalent linking group represented by any of the following formulas:

[0049] In the above formula, *1 indicates the bonding position to the oxygen atom in the above formula (a3-2-i), (a3-2-ii), or (a3-2-iii), and *2 indicates the bonding position to the carbon atom of the lactone structure. １ represents an alkylene group having 1 to 6 carbon atoms.

[0050] The resin (A3) used in one embodiment of the present invention may contain other structural units in addition to the structural units (a3-1) and (a3-2). Examples of such other structural units include structural units derived from alkyl (meth)acrylates; hydroxy group-containing monomers; epoxy group-containing monomers; alicyclic structure-containing monomers; olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene, and chloroprene; and monomers such as styrene, α-methylstyrene, vinyltoluene, acrylonitrile, (meth)acrylamide, (meth)acrylonitrile, (meth)acryloylmorpholine, and N-vinylpyrrolidone. Details of these monomers are the same as those described in the section on resin (A2).

[0051] In the resin (A3) used in one embodiment of the present invention, the combined amount of the structural units (a3-1) and (a3-2) is preferably 30 to 100 mol %, more preferably 50 to 100 mol %, even more preferably 70 to 100 mol %, still more preferably 80 to 100 mol %, and particularly preferably 90 to 100 mol %, based on the total amount (100 mol %) of structural units in the resin (A3).

[0052] The weight average molecular weight (Mw) of the resin (A3) used in one embodiment of the present invention is preferably 400 to 50,000, more preferably 2,000 to 40,000, even more preferably 3,000 to 30,000, and still more preferably 4,000 to 20,000. The molecular weight distribution (Mw / Mn) of the resin (A3) is preferably 6.0 or less, more preferably 5.0 or less, even more preferably 4.0 or less, and still more preferably 3.2 or less, and is preferably 1.01 or more, more preferably 1.05 or more, and even more preferably 1.1 or more.

[0053] [Resin (A4)] The resin (A4) used in one embodiment of the present invention is a resin having two or more structural units (a2-1) derived from a phenolic hydroxyl group-containing compound, a structural unit (a2-2) that can be decomposed by the action of an acid, base, or heat to form an acidic functional group, a structural unit (a3-1) having an adamantane structure, and a structural unit (a3-2) having a lactone structure (excluding resins (A2) and (A3)). There is no particular limitation, and known resins are used. For example, the resins listed in the book "Lithography Technology: 40 Years," International Patent Publication No. 2014-175275, International Patent Publication No. 2015-115613, International Patent Publication No. 2020-137935, International Patent Publication No. 2021-029395, and International Patent Publication No. 2021-029396 can be used.

[0054] The weight average molecular weight (Mw) of the resin (A4) used in one embodiment of the present invention is preferably 400 to 50,000, more preferably 2,000 to 40,000, even more preferably 3,000 to 30,000, and still more preferably 4,000 to 20,000. The molecular weight distribution (Mw / Mn) of the resin (A4) is preferably 6.0 or less, more preferably 5.0 or less, even more preferably 4.0 or less, and still more preferably 3.2 or less, and is preferably 1.01 or more, more preferably 1.05 or more, and even more preferably 1.1 or more.

[0055] <Component (B): Solvent> A resist composition according to one embodiment of the present invention contains a solvent (B) that includes a compound (B1) represented by the following general formula (b-1): The compound (B1) may be used alone, or two or more types of compound (B1) may be used in combination.

[0056]

[0057] In the above formula (b-1), R １ is an alkyl group having 1 to 10 carbon atoms. The alkyl group may be a linear alkyl group or a branched alkyl group. １ Examples of the alkyl group that can be selected as the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, and a decyl group.

[0058] Among these, in one embodiment of the present invention, R in the general formula (b-1) １ is preferably a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a s-butyl group, or a t-butyl group, more preferably an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a s-butyl group, or a t-butyl group, even more preferably an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a s-butyl group, or a t-butyl group, and still more preferably an i-propyl group, an n-butyl group, or an i-butyl group.

[0059] Furthermore, in the resist composition according to one embodiment of the present invention, the component (B) preferably includes a solvent (B2) other than the compound (B1). Examples of the solvent (B2) include lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, and dipropylene glycol monoacetate; compounds having an ether bond such as monoalkyl ethers or monophenyl ethers of the polyhydric alcohols such as 1-methoxy-2-propanol or the compounds having an ester bond, such as monomethyl ether, monoethyl ether, monopropyl ether, and monobutyl ether; Examples of the solvent (B2) include cyclic ethers such as dioxane, esters other than the compound (B1) such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl α-methoxyisobutyrate, methyl β-methoxyisobutyrate, ethyl 2-ethoxyisobutyrate, methyl methoxypropionate, ethyl ethoxypropionate, methyl α-formyloxyisobutyrate, methyl β-formyloxyisobutyrate, and methyl 3-hydroxyisobutyrate, aromatic organic solvents such as anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetole, butylphenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene, and dimethyl sulfoxide (DMSO). These solvents (B2) may be used alone or in combination of two or more.

[0060] However, from the viewpoint of using a photoresist material that is capable of forming a thick resist film, in the resist composition of the present invention, the content of compound (B1) in component (B) is preferably 20 to 100 mass%, more preferably 30 to 100 mass%, even more preferably 50 to 100 mass%, still more preferably 60 to 100 mass%, and particularly preferably 70 to 100 mass%, relative to the total amount (100 mass%) of component (B) contained in the resist composition.

[0061] In one embodiment of the present invention, component (B) used preferably contains, as solvent (B2), one or more solvents selected from the group consisting of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, methyl 3-hydroxyisobutyrate, and 1-methoxy-2-propanol, from the viewpoint of solubility of the acid generator used in the resist composition. The inclusion of methyl α-methoxyisobutyrate is preferred from the viewpoint of solubility of the resin used in the resist composition. The inclusion of methyl α-formyloxyisobutyrate or methyl α-acetyloxyisobutyrate is preferred from the viewpoint of solubility of the resin used in the resist composition and thickening of the resist film. The inclusion of methyl 3-hydroxyisobutyrate is preferred from the viewpoint of obtaining a rectangular resist pattern. The inclusion of 1-methoxy-2-propanol is preferred from the viewpoint of obtaining a resist film with high in-plane uniformity. The method for mixing methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, methyl 3-hydroxyisobutyrate, or 1-methoxy-2-propanol is not particularly limited, and they can be incorporated by either a method of adding methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl 3-hydroxyisobutyrate, or 1-methoxy-2-propanol to compound (B1), or a method of mixing them as by-products or by mixing them in the production process of compound (B1).

[0062] The content of the solvent (B2) is not limited, but is preferably less than 100% by mass, based on the total amount (100% by mass) of the compound (B1), from the viewpoint of improving productivity by shortening the drying time of the coating film, and is 70% by mass or less, and from the viewpoint of increasing the dissolving power of the solvent while ensuring an appropriate drying time, it is 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0.01% by mass or less. From the viewpoint of improving the storage stability of the resist composition, it is preferably 0.0001% by mass or more, from the viewpoint of improving the solubility of the active ingredients of the resist composition, it is more preferably 0.001% by mass or more, and from the viewpoint of suppressing defects in the resist film, it is even more preferably 0.01% by mass or more.

[0063] The content of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, methyl 3-hydroxyisobutyrate, or 1-methoxy-2-propanol is not limited, but is preferably less than 100% by mass, based on the total amount (100% by mass) of the resist composition, from the perspective of improving productivity by shortening the drying time of the coated film, and more preferably 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, 1% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.01% by mass or less. From the perspective of improving the storage stability of the resist composition, the content is preferably 0.0001% by mass or more, from the perspective of improving the solubility of the active ingredients of the resist composition, more preferably 0.001% by mass or more, and even more preferably 0.01% by mass or more, from the perspective of suppressing defects in the resist film.

[0064] The content of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, methyl 3-hydroxyisobutyrate, or 1-methoxy-2-propanol is preferably 100% by mass or less, based on the total amount (100% by mass) of compound (B1), from the perspective of improving productivity by shortening the drying time of the resist composition, more preferably 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.01% by mass or less. From the perspective of improving the storage stability of the resist composition, the content is preferably 0.0001% by mass or more, from the perspective of improving the solubility of the active ingredients of the resist composition, more preferably 0.001% by mass or more, and even more preferably 0.01% by mass or more from the perspective of suppressing defects in the resist film.

[0065] From the viewpoint of in-plane uniformity of the coating film, the content of 1-methoxy-2-propanol is preferably 1 to 98 mass%, and more preferably 16 to 98 mass%, based on the total amount (100 mass%) of the resist composition, and is also preferably 1 to 99 mass%, and more preferably 30 to 99 mass%, based on the total amount (100 mass%) of compound (B1).

[0066] In one embodiment of the present invention, component (B) used also preferably includes, as solvent (B2), one or more selected from the group consisting of methyl α-formyloxyisobutyrate, methyl α-acetyloxyisobutyrate, and methyl 3-hydroxyisobutyrate.

[0067] In the resist composition of the present invention, the content of component (B) is appropriately set depending on the application, but can be 50% by mass or more, 54% by mass or more, 58% by mass or more, 60% by mass or more, 65% by mass or more, 69% by mass or more, 74% by mass or more, 77% by mass or more, 80% by mass or more, 82% by mass or more, 84% by mass or more, 88% by mass or more, 90% by mass or more, 94% by mass or more, or 97% by mass or more, based on the total amount (100% by mass) of the resist composition. The upper limit of the content of component (B) is appropriately set in accordance with the content of component (A), but can be 99% by mass or less, 98% by mass or less, 96% by mass or less, 93% by mass or less, 91% by mass or less, 86% by mass or less, 81% by mass or less, 76% by mass or less, 71% by mass or less, 66% by mass or less, or 61% by mass or less, based on the total amount (100% by mass) of the resist composition. The content of component (B) can be determined in any combination by appropriately selecting from the above-mentioned upper and lower limit values.

[0068] <Component (C): Additive Selected from a Photosensitizer and an Acid Generator> The resist composition of one embodiment of the present invention preferably contains at least one additive (C) selected from a photosensitizer and an acid generator. Component (C) may be used alone, or two or more types may be used in combination. In the resist composition of one embodiment of the present invention, the amount of component (C) contained per 100 parts by mass of resin (A) contained in the resist composition is preferably 0.01 to 80 parts by mass, more preferably 0.05 to 65 parts by mass, even more preferably 0.1 to 50 parts by mass, and even more preferably 0.5 to 30 parts by mass. The photosensitizer and acid generator contained as component (C) will be described below.

[0069] [Photosensitizer] The photosensitizer that can be selected as component (C) is not particularly limited, as long as it is a photosensitive component that is generally used in positive resist compositions. The photosensitizer may be used alone, or two or more types may be used in combination.

[0070] Examples of the photosensitizer used in one embodiment of the present invention include a reaction product of an acid chloride with a compound having a functional group (hydroxyl group, amino group, etc.) that can condense with the acid chloride. Examples of the acid chloride include naphthoquinone diazide sulfonic acid chloride and benzoquinone diazide sulfonic acid chloride, and specific examples thereof include 1,2-naphthoquinone diazide-5-sulfonyl chloride and 1,2-naphthoquinone diazide-4-sulfonyl chloride. Examples of the compound capable of condensing with an acid chloride having a functional group include hydroxybenzophenones such as hydroquinone, resorcinol, 2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and 2,2',3,4,6'-pentahydroxybenzophenone. Examples of the photosensitizer used in one embodiment of the present invention include hydroxyphenylalkanes such as benzophenones, bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, and bis(2,4-dihydroxyphenyl)propane; and hydroxytriphenylmethanes such as 4,4',3",4"-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane and 4,4',2",3",4"-pentahydroxy-3,5,3',5'-tetramethyltriphenylmethane. Note that the photosensitizer used in one embodiment of the present invention may be a commercially available product such as "DTEP-350" (diazonaphthoquinone-type photosensitizer, manufactured by Daito Chemiks Co., Ltd.).

[0071] [Acid Generator] The acid generator that can be selected as component (C) may be any compound that can generate an acid directly or indirectly upon irradiation with radiation such as visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet light (EUV), X-ray, ion beam, etc. Specific examples of suitable acid generators include compounds represented by any of the following general formulas (c-1) to (c-8):

[0072] (Compound represented by general formula (c-1))

[0073] In the above formula (c-1), R １３ are each independently a hydrogen atom, a linear, branched, or cyclic alkyl group, a linear, branched, or cyclic alkoxy group, a hydroxyl group, or a halogen atom. － is a sulfonate ion or a halide ion having an alkyl group, an aryl group, a halogen-substituted alkyl group, or a halogen-substituted aryl group.

[0074] Examples of the compound represented by the general formula (c-1) include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, diphenyltolylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, diphenyl-4-methylphenylsulfonium trifluoromethanesulfonate, di-2,4,6-trimethylphenylsulfonium trifluoromethanesulfonate, diphenyl-4-t-butoxyphenylsulfonium trifluoromethanesulfonate, diphenyl-4-t-butoxyphenylsulfonium nonafluoro-n-butanesulfonate, diphenyl-4-hydroxyphenylsulfonium trifluoromethanesulfonate, bis(4-fluorophenyl)-4-hydroxyphenylsulfonium trifluoromethanesulfonate, diphenyl-4-hydroxyphenylsulfonium nonafluoro-n-butanesulfonate, bis(4-hydroxyphenyl)-phenylsulfonium trifluoromethanesulfonate, tri(4-methylphenyl)-4-hydroxyphenylsulfonium trifluoromethanesulfonate, tri(4-fluorophenyl)sulfonium trifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate, triphenylsulfonium benzenesulfonate, diphenyl-2,4,6-trimethylphenyl-p-toluenesulfonate, diphenyl-2,4,6-trimethylphenylsulfonium-2-trifluoromethylbenzenesulfonate, diphenyl-2,4,6-trimethylphenylsulfonium-4-trifluoromethylbenzenesulfonate, diphenyl-2,4,6-trimethylphenylsulfonium-2,4-difluorobenzenesulfonate, diphenyl-2,4,6-trimethylphenylsulfonium hexafluorobenzenesulfonate, diphenyl naphthylsulfonium trifluoromethanesulfonate, diphenyl-4-hydroxyphenylsulfonium-p-toluenesulfonate, triphenylsulfonium 10-camphorsulfonate, diphenyl-4-hydroxyphenylsulfonium 10-camphorsulfonate, and cyclo(1,It is preferable that the compound is at least one selected from the group consisting of 3-perfluoropropanedisulfone)imidate.

[0075] (Compound represented by general formula (c-2))

[0076] In the above formula (c-2), R １４ are each independently a hydrogen atom, a linear, branched, or cyclic alkyl group, a linear, branched, or cyclic alkoxy group, a hydroxyl group, or a halogen atom. － is a sulfonate ion or a halide ion having an alkyl group, an aryl group, a halogen-substituted alkyl group, or a halogen-substituted aryl group.

[0077] Examples of the compound represented by the general formula (c-2) include bis(4-t-butylphenyl)iodonium trifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate, bis(4-t-butylphenyl)iodonium perfluoro-n-octanesulfonate, bis(4-t-butylphenyl)iodonium p-toluenesulfonate, bis(4-t-butylphenyl)iodonium benzenesulfonate, and bis(4-t-butylphenyl)iodonium-2-trifluoromethylbenzenesulfonate. iodonium 4-trifluoromethylbenzenesulfonate, bis(4-t-butylphenyl)iodonium 2,4-difluorobenzenesulfonate, bis(4-t-butylphenyl)iodonium hexafluorobenzenesulfonate, bis(4-t-butylphenyl)iodonium 10-camphorsulfonate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoromethanesulfonate diphenyliodonium hexafluorobenzenesulfonate, di(4-trifluoromethylphenyl)iodonium trifluoromethanesulfonate, di(4-trifluoromethylphenyl)iodonium nonafluoro-n-butanesulfonate, di(4-trifluoromethylphenyl)iodonium perfluoro-n-octanesulfonate, di(4-trifluoromethylphenyl)iodonium p-toluenesulfonate, di(4-trifluoromethylphenyl)iodonium benzenesulfonate, and di(4-trifluoromethylphenyl)iodonium 10-camphorsulfonate.

[0078] (Compound represented by general formula (c-3))

[0079] In the above formula (c-3), Q is an alkylene group, an arylene group, or an alkoxylene group. １５ is an alkyl group, an aryl group, a halogen-substituted alkyl group, or a halogen-substituted aryl group.

[0080] Examples of the compound represented by the general formula (c-3) include N-(trifluoromethylsulfonyloxy)succinimide, N-(trifluoromethylsulfonyloxy)phthalimide, N-(trifluoromethylsulfonyloxy)diphenylmaleimide, N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(trifluoromethylsulfonyloxy)naphthylimide, N-(10-camphorsulfonyloxy)succinimide, N-(10-camphorsulfonyloxy)succinimide, N-(10-camphorsulfonyloxy)phthalimide, N-(10-camphorsulfonyloxy)diphenylmaleimide, N-(10-camphorsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(10-camphorsulfonyloxy)naphthylimide, N-(n-octanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(n-octanesulfonyloxy)naphthylimide, N-(p-toluenesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide cyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(p-toluenesulfonyloxy)naphthylimide, N-(2-trifluoromethylbenzenesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(2-trifluoromethylbenzenesulfonyloxy)naphthylimide, N-(4-trifluoromethylbenzenesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(4-trifluoromethylbenzenesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide N-(perfluorobenzenesulfonyloxy)naphthyl imide, N-(perfluorobenzenesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(perfluorobenzenesulfonyloxy)naphthyl imide, N-(1-naphthalenesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(1-naphthalenesulfonyloxy)naphthyl imide, N-(nonafluoro-n-butanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,Preferably, the aryl group is at least one selected from the group consisting of N-(perfluoro-n-octanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, N-(nonafluoro-n-butanesulfonyloxy)naphthylimide, N-(perfluoro-n-octanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide, and N-(perfluoro-n-octanesulfonyloxy)naphthylimide.

[0081] (Compound represented by general formula (c-4))

[0082] In the above formula (c-4), R １６ are each independently a linear, branched, or cyclic alkyl group, an aryl group, a heteroaryl group, or an aralkyl group, and at least one hydrogen atom of these groups may be substituted with an optional substituent.

[0083] The compound represented by general formula (c-4) is preferably at least one selected from the group consisting of diphenyl disulfone, di(4-methylphenyl)disulfone, dinaphthyl disulfone, di(4-t-butylphenyl)disulfone, di(4-hydroxyphenyl)disulfone, di(3-hydroxynaphthyl)disulfone, di(4-fluorophenyl)disulfone, di(2-fluorophenyl)disulfone, and di(4-trifluoromethylphenyl)disulfone.

[0084] (Compound represented by general formula (c-5))

[0085] In the above formula (c-5), R １７ are each independently a linear, branched, or cyclic alkyl group, an aryl group, a heteroaryl group, or an aralkyl group, and at least one hydrogen atom of these groups may be substituted with an optional substituent.

[0086] The compound represented by general formula (c-5) is preferably at least one selected from the group consisting of α-(methylsulfonyloxyimino)-phenylacetonitrile, α-(methylsulfonyloxyimino)-4-methoxyphenylacetonitrile, α-(trifluoromethylsulfonyloxyimino)-phenylacetonitrile, α-(trifluoromethylsulfonyloxyimino)-4-methoxyphenylacetonitrile, α-(ethylsulfonyloxyimino)-4-methoxyphenylacetonitrile, α-(propylsulfonyloxyimino)-4-methylphenylacetonitrile, and α-(methylsulfonyloxyimino)-4-bromophenylacetonitrile.

[0087] (Compound represented by general formula (c-6))

[0088] In the above formula (c-6), R １８ are each independently a halogenated alkyl group having one or more chlorine atoms and one or more bromine atoms. The halogenated alkyl group preferably has 1 to 5 carbon atoms.

[0089] (Compounds represented by general formulas (c-7) and (c-8))

[0090] In the above formulas (c-7) and (c-8), R １９ and R ２０ are each independently an alkyl group having 1 to 3 carbon atoms (e.g., methyl, ethyl, n-propyl, i-propyl), a cycloalkyl group having 3 to 6 carbon atoms (e.g., cyclopentyl, cyclohexyl), an alkoxyl group having 1 to 3 carbon atoms (e.g., methoxy, ethoxy, propoxy), or an aryl group having 6 to 10 carbon atoms (e.g., phenyl, toluoyl, naphthyl), and preferably an aryl group having 6 to 10 carbon atoms. １９ and L ２０are each independently an organic group having a 1,2-naphthoquinonediazide group, and specifically, a 1,2-quinonediazide sulfonyl group such as a 1,2-naphthoquinonediazide-4-sulfonyl group, a 1,2-naphthoquinonediazide-5-sulfonyl group, or a 1,2-naphthoquinonediazide-6-sulfonyl group is preferred, with a 1,2-naphthoquinonediazide-4-sulfonyl group or a 1,2-naphthoquinonediazide-5-sulfonyl group being more preferred. p is an integer of 1 to 3, q ​​is an integer of 0 to 4, and 1≦p+q≦5. J １９ represents a single bond, an alkylene group having 1 to 4 carbon atoms, a cycloalkylene group having 3 to 6 carbon atoms, a phenylene group, a group represented by the following formula (c-7-i), a carbonyl group, an ester group, an amide group, or —O—. １９ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and X ２０ are each independently a group represented by the following formula (c-8-i):

[0091]

[0092] In the above formula (c-8-i), Z ２２ are each independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. ２２ are each independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an alkoxyl group having 1 to 6 carbon atoms; and r is an integer of 0 to 3.

[0093] The acid generator used in one embodiment of the present invention may be an acid generator other than the compounds represented by any one of general formulas (c-1) to (c-8) above. Examples of such an acid generator include bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylphenylsulfonyl)diazomethane, bis(tert-butylsulfonyl)diazomethane, bis(n-butylsulfonyl)diazomethane, bis(isobutylsulfonyl)diazomethane, bis(isopropylsulfonyl)diazomethane, bis(n-propylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(isopropylsulfonyl)diazomethane, 1,3-bis(cyclohexylsulfonylazomethylsulfonyl)propane, 1,4-bis(phenyl and bissulfonyldiazomethanes such as 1,6-bis(phenylsulfonylazomethylsulfonyl)butane, 1,6-bis(phenylsulfonylazomethylsulfonyl)hexane, and 1,10-bis(cyclohexylsulfonylazomethylsulfonyl)decane; and halogen-containing triazine derivatives such as 2-(4-methoxyphenyl)-4,6-(bistrichloromethyl)-1,3,5-triazine, 2-(4-methoxynaphthyl)-4,6-(bistrichloromethyl)-1,3,5-triazine, tris(2,3-dibromopropyl)-1,3,5-triazine, and tris(2,3-dibromopropyl)isocyanurate.

[0094] <Other Additives> The resist composition of one embodiment of the present invention may contain components other than the above-mentioned components (A) to (C). Examples of other components include one or more selected from the group consisting of an acid crosslinker, an acid diffusion controller, a dissolution promoter, a dissolution controller, a sensitizer, a surfactant, an organic carboxylic acid, a phosphorus oxoacid, or a derivative thereof. The content of each of these other components is appropriately selected depending on the type of component and the type of resin (A), but is preferably 0.001 to 100 parts by mass, more preferably 0.01 to 70 parts by mass, even more preferably 0.1 to 50 parts by mass, and even more preferably 0.3 to 30 parts by mass, per 100 parts by mass of resin (A) contained in the resist composition.

[0095] (Acid Crosslinking Agent) The acid crosslinking agent may be any compound having a crosslinkable group capable of crosslinking with the resin (A), and is appropriately selected depending on the type of the resin (A). Examples of the acid crosslinking agent used in one embodiment of the present invention include methylol group-containing compounds such as methylol group-containing melamine compounds, methylol group-containing benzoguanamine compounds, methylol group-containing urea compounds, methylol group-containing glycoluril compounds, and methylol group-containing phenolic compounds; alkoxyalkyl group-containing compounds such as alkoxyalkyl group-containing melamine compounds, alkoxyalkyl group-containing benzoguanamine compounds, alkoxyalkyl group-containing urea compounds, alkoxyalkyl group-containing glycoluril compounds, and alkoxyalkyl group-containing phenolic compounds; carboxymethyl group-containing compounds such as carboxymethyl group-containing melamine compounds, carboxymethyl group-containing benzoguanamine compounds, carboxymethyl group-containing urea compounds, carboxymethyl group-containing glycoluril compounds, and carboxymethyl group-containing phenolic compounds; bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, novolac resin type epoxy compounds, resol resin type epoxy compounds, and poly(hydroxystyrene) type epoxy compounds; and the like. These acid crosslinking agents may be used alone or in combination of two or more.

[0096] (Acid Diffusion Controller) The acid diffusion controller is an additive that controls the diffusion of an acid generated from an acid generator upon irradiation in a resist film, thereby preventing undesirable chemical reactions in unexposed regions. The acid diffusion controller used in one embodiment of the present invention is not particularly limited, and examples thereof include radiation-decomposable basic compounds such as nitrogen atom-containing basic compounds, basic sulfonium compounds, and basic iodonium compounds. These acid diffusion controllers may be used alone or in combination of two or more.

[0097] (Dissolution promoter) The dissolution promoter is an additive that has the effect of increasing the solubility of the resin (A) in the developer and appropriately increasing the dissolution rate of the resin (A) during development. The dissolution promoter used in one embodiment of the present invention is not particularly limited, and examples thereof include phenolic compounds such as bisphenols and tris(hydroxyphenyl)methane. These dissolution promoters may be used alone or in combination of two or more.

[0098] (Dissolution Controller) The dissolution controller is an additive that has the effect of controlling the solubility of the resin (A) in the developer when the solubility of the resin (A) is too high, thereby appropriately reducing the dissolution rate during development. The dissolution controller used in one embodiment of the present invention is not particularly limited, and examples thereof include aromatic hydrocarbons such as phenanthrene, anthracene, and acenaphthene; ketones such as acetophenone, benzophenone, and phenyl naphthyl ketone; and sulfones such as methyl phenyl sulfone, diphenyl sulfone, and dinaphthyl sulfone. These dissolution controllers may be used alone or in combination of two or more.

[0099] (Sensitizer) A sensitizer is an additive that absorbs the energy of irradiated radiation, transfers the energy to an acid generator, and thereby increases the amount of acid generated, thereby improving the apparent sensitivity of the resist. Examples of sensitizers used in one embodiment of the present invention include benzophenones, biacetyls, pyrenes, phenothiazines, and fluorenes. These sensitizers may be used alone or in combination of two or more.

[0100] (Surfactant) A surfactant is an additive that has the effect of improving the coatability and striation of the resist composition, the developability of the resist, etc. The surfactant used in one embodiment of the present invention may be any of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, but nonionic surfactants are preferred. Examples of nonionic surfactants include polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkyl phenyl ethers, and higher fatty acid diesters of polyethylene glycol. These surfactants may be used alone or in combination of two or more.

[0101] (Organic Carboxylic Acid or Phosphorus Oxo Acid or Derivative Thereof) An organic carboxylic acid or a phosphorus oxo acid or a derivative thereof is an additive that prevents sensitivity degradation or improves resist pattern shape, deposition stability, etc. The organic carboxylic acid used in one embodiment of the present invention is not particularly limited, and examples thereof include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, etc. Furthermore, examples of phosphorus oxo acids or derivatives thereof include phosphoric acid, di-n-butyl phosphate, diphenyl phosphate, and other phosphoric acid or ester derivatives thereof; phosphonic acid, dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, dibenzyl phosphonate, and other phosphonic acid or ester derivatives thereof; phosphinic acid, phenylphosphinic acid, and other phosphinic acid or ester derivatives thereof; and these may be used alone or in combination of two or more.

[0102] (Other Components) Furthermore, the resist composition of one embodiment of the present invention may contain, in addition to the other components described above, dyes, pigments, adhesion aids, antihalation agents, storage stabilizers, antifoaming agents, shape improvers, and the like.

[0103] [Method of Forming a Resist Film] As described above, the resist composition of one embodiment of the present invention is capable of forming a thick resist film suitable for the production of various devices, even though the content of active ingredients including a resin is limited to a predetermined value or less. The method of forming a resist film is not particularly limited, but includes, for example, a method having the following step (1), and preferably a method further having steps (2) and (3). Step (1): A step of applying the resist composition of one embodiment of the present invention described above onto a substrate to form a coating film. Step (2): A step of performing a heat treatment after step (1). Step (3): A step of forming a resist pattern.

[0104] <Step (1)> In step (1), the substrate on which the coating film is formed is not particularly limited and includes, for example, a substrate for electronic components, a substrate on which a predetermined wiring pattern is formed, etc. More specifically, examples include a silicon wafer, a metal substrate such as copper, chromium, iron, aluminum, etc., a glass substrate, etc. The material for the wiring pattern is not particularly limited and examples include copper, aluminum, nickel, gold, etc.

[0105] The substrate used in one embodiment of the present invention may, if necessary, have an underlayer film formed from a material selected from organic materials and inorganic materials on the surface on which the coating film is formed. When such a substrate with an underlayer film is used, the coating film is formed on the underlayer film. Examples of the underlayer film-forming material for forming the underlayer film include the underlayer film-forming composition described in WO 2016 / 021511.

[0106] The substrate used in one embodiment of the present invention may be surface-treated, if necessary, by applying a prewetting agent to the surface on which the coating film is to be formed. Generally, a significant amount of resist composition is scattered from the outer periphery, where the peripheral speed is significantly higher than that of the center, resulting in increased consumption of the resist composition. To address this issue, applying a prewetting agent to the surface of the substrate facilitates diffusion of the resist composition on the substrate, thereby reducing the amount of resist composition supplied. Examples of prewetting agents include cyclohexanone, ethyl lactate, and methyl-3-methoxypropionate. Specific surface treatment methods using prewetting agents are not particularly limited, but examples include the method described in JP-A-2004-39828.

[0107] As a coating means for applying the resist composition onto a substrate, known means can be appropriately applied, for example, spin coating, cast coating, roll coating, etc. As described above, the resist composition of one embodiment of the present invention can be used to form a thick coating film by these coating means.

[0108] <Step (2)> In one embodiment of the present invention, step (2) preferably includes a heat treatment step performed after step (1). Heat treatment can improve adhesion between the substrate and the resist film. The heating temperature for the heat treatment in this step is appropriately set depending on the composition of the resist composition, but is preferably 20 to 250°C, more preferably 20 to 150°C.

[0109] <Step (3)> Step (3) is a step of exposing the formed resist film through a desired mask pattern to form a predetermined resist pattern. Examples of radiation to be irradiated during exposure include visible light, ultraviolet light such as g-line (wavelength 436 nm) and i-line (wavelength 365 nm), far ultraviolet light such as ArF excimer laser (wavelength 193 nm) and KrF excimer laser (wavelength 248 nm), excimer laser, electron beam, extreme ultraviolet light (EUV), X-rays such as synchrotron radiation, and ion beams. From the viewpoint of stably forming a highly accurate fine pattern during exposure, it is preferable to perform a heat treatment after radiation irradiation. The heating temperature for the heat treatment is preferably 20 to 250°C, more preferably 20 to 150°C.

[0110] The exposed resist film is then developed with a developer to form a desired resist pattern. The developer used is preferably a solvent having a solubility parameter (SP value) close to that of the resin (A) contained in the resist composition, and examples of the developer include polar solvents such as ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents, hydrocarbon solvents, and aqueous alkaline solutions. Examples of alkaline compounds contained in aqueous alkaline solutions include mono-, di-, or tri-alkylamines; mono-, di-, or tri-alkanolamines; heterocyclic amines; tetraalkylammonium hydroxides; choline; 1,8-diazabicyclo[5,4,0]-7-undecene; and 1,5-diazabicyclo[4,3,0]-5-nonene.

[0111] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by piling up the developer on the surface of the substrate by surface tension and leaving it standing for a certain period of time (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), a method of continuously dispensing the developer while scanning a developer dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispense method), etc. The developing time is not particularly limited, but is preferably 10 to 90 seconds.

[0112] After development, a step of stopping development while replacing the solvent with another solvent may be carried out. After development, a step of rinsing using a rinse containing an organic solvent is preferably carried out. The rinse liquid used in the rinse step after development is not particularly limited as long as it does not dissolve the formed resist pattern, and a solution containing a general organic solvent or water can be used. As the rinse liquid, a rinse liquid containing at least one organic solvent selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents is preferably used. The time for performing the rinse step is not particularly limited, but is preferably 10 to 90 seconds.

[0113] In the rinsing step, the developed substrate is washed with a rinse solution containing the organic solvent. The method of the washing treatment is not particularly limited, but examples thereof include a method of continuously applying the rinse solution onto a substrate rotating at a constant speed (spin coating method), a method of immersing the substrate in a tank filled with the rinse solution for a certain period of time (dipping method), and a method of spraying the rinse solution onto the surface of the substrate (spray method).

[0114] After forming a resist pattern, etching is performed to obtain a patterned wiring substrate. Etching can be performed by known methods such as dry etching using plasma gas and wet etching using an alkaline solution, cupric chloride solution, ferric chloride solution, etc. After forming the resist pattern, plating may be performed. The plating method is not particularly limited, but examples include copper plating, solder plating, nickel plating, and gold plating.

[0115] The remaining resist pattern after etching can be stripped using an organic solvent. Examples of such organic solvents include, but are not limited to, PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), and EL (ethyl lactate). Examples of the stripping method include, but are not limited to, immersion and spraying. The wiring substrate on which the resist pattern is formed may be a multilayer wiring substrate and may have small-diameter through-holes. In this embodiment, the wiring substrate can also be formed by a method in which, after forming the resist pattern, a metal is vapor-deposited in a vacuum, and then the resist pattern is dissolved in a solution, i.e., a lift-off method.

[0116] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The values ​​in the examples were measured using the following methods or devices.

[0117] (1) Film Thickness of Coating Film The film thickness of a coating film formed from a resist composition was measured in a constant temperature and humidity chamber at a temperature of 23°C and a humidity of 50% (relative humidity) using a film thickness measurement system (device name "F20", manufactured by Filmetrics, Inc.).

[0118] (2) Content of structural units in resin The content of structural units in resin is １３ C-NMR (model "JNM-ECA500", manufactured by JEOL Ltd., 125 MHz) was used, using deuterated chloroform as a solvent. １３ Measurement was performed by integrating 1024 times in the quantitative mode of C.

[0119] (3) Weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of resin The Mw and Mn of the resin were measured by gel permeation chromatography (GPC) under the following conditions using polystyrene as a standard substance: Apparatus: Hitachi LaChrom series Detector: RI detector L-2490 Column: Tosoh TSKgel GMHHR-M (2 columns) + guard column HHR-H Solvent: THF (containing stabilizer) Flow rate: 1 mL / min Column temperature: 40°C The ratio of Mw to Mn of the resin [Mw / Mn] was then calculated as the molecular weight distribution of the resin.

[0120] The solvents used in the following examples and comparative examples are as follows: <Component (B1)> HBM: methyl 2-hydroxyisobutyrate, in the general formula (b-1) above, R １ is a methyl group. iPHIB: isopropyl 2-hydroxyisobutyrate, a compound in which R １ is an i-propyl group. iBHIB: isobutyl 2-hydroxyisobutyrate, a compound in which R １ is an i-butyl group. nBHIB: n-butyl 2-hydroxyisobutyrate, a compound in which R １ is an n-butyl group. <Component (B2)> PGMEA: propylene glycol monomethyl ether acetate MMP: methyl 3-methoxypropionate nBuOAc: n-butyl acetate EL: ethyl lactate

[0121] [Resist Compositions Containing Liquid Crystal Resin] Examples 1a to 47a, Comparative Examples 1a to 6a A cresol novolac resin prepared by mixing "EP4080G" and "EP4050G" (both manufactured by Asahi Organic Chemicals Co., Ltd.) at a 1:1 (mass ratio) was used as the liquid crystal resin. 84 parts by mass of the cresol novolac resin and 16 parts by mass of a diazonaphthoquinone photosensitizer (product name "DTEP-350", manufactured by Daito Chemiks Co., Ltd.) were mixed and dissolved in a solvent of the type and blending ratio shown in Table 1 to prepare resist compositions having the active ingredient (cresol novolac resin and photosensitizer) concentrations shown in Tables 1 and 2. The prepared resist compositions were then spin-coated onto silicon wafers at 1600 rpm to form coatings, which were then pre-baked at 110°C for 90 seconds to form resist films. The film thicknesses at five randomly selected locations on the resist film were measured, and the average film thickness of the five locations was calculated as the average film thickness. The results are shown in Tables 1 and 2.

[0122]

[0123]

[0124] Table 1 shows that the resist compositions prepared in Examples 1a to 14a were able to form thicker resist films than the resist compositions of Comparative Examples 1a to 6a, which had similar resin concentrations. Table 2 also shows that the resist compositions prepared in Examples 15a to 47a were able to form thicker resist films, despite having a low liquid crystal resin content of 20 to 25% by mass.

[0125] [Resist Compositions Containing KrF Resins] Examples 1b to 35b, Comparative Examples 1b to 19b A copolymer (manufactured by Maruzen Petrochemical Co., Ltd., Mw = 20,000) having structural units of hydroxystyrene / t-butyl acrylate = 2 / 1 (molar ratio) was used as the KrF resin. The copolymer was mixed with a mixed solvent of the type and blending ratio shown in Tables 3 and 4 to prepare resist compositions with the active ingredient (KrF resin) concentration shown in Tables 3 and 4. The prepared resist compositions were then spin-coated at 1600 rpm onto silicon wafers to form coatings, which were then pre-baked at 110°C for 90 seconds to form resist films. The film thickness was measured at five randomly selected locations on the resist film, and the average film thickness of the five locations was calculated. The results are shown in Tables 3 and 4.

[0126]

[0127]

[0128] Tables 3 and 4 show that the resist compositions prepared in Examples 1b to 35b are capable of forming thicker resist films than the resist compositions of Comparative Examples 1b to 19b having the same resin concentration.

[0129] [Resist Compositions Containing ArF Resins] Synthesis Examples 1 to 6 (Synthesis of ArF Resins (i) to (vi)) (1) Raw Material Monomers The following raw material monomers were used in synthesizing ArF Resins (i) to (vi). The structures of the raw material monomers are shown in Table 5. EADM: 2-ethyl-2-adamantyl methacrylate MADM: 2-methyl-2-adamantyl methacrylate NML: 2-methacryloyloxy-4-oxatricyclo[4.2.1.0] ３．７ ]nonan-5-one GBLM: α-methacryloyloxy-γ-butyrolactone HADM: 3-hydroxy-1-adamantyl methacrylate

[0130]

[0131] (2) Synthesis of ArF Resins (i) to (vi) A total of 10 g of raw material monomers were mixed in a 300 mL round-bottom flask in the molar ratios shown in Table 6. 300 g of tetrahydrofuran (Wako Pure Chemical Industries, Ltd., special grade reagent, stabilizer-free) was added, followed by stirring and degassing for 30 minutes under a nitrogen stream. After degassing, 0.95 g of 2,2'-azobis(isobutyronitrile) (Tokyo Chemical Industry Co., Ltd., reagent) was added, and polymerization was carried out at 60°C under a nitrogen stream to obtain a resin of the desired molecular weight. After completion of the reaction, the reaction solution was cooled to room temperature (25°C) and added dropwise to a large excess of hexane to precipitate the polymer. The precipitated polymer was filtered off, and the resulting solid was washed with methanol and then dried under reduced pressure at 50°C for 24 hours to obtain the desired ArF Resins (i) to (vi), respectively. For the resulting ArF resins (i) to (vi), the content of each structural unit, as well as Mw, Mn, and Mw / Mn, were measured and calculated based on the above-mentioned measurement methods. The results are shown in Table 6.

[0132]

[0133] Examples 1c to 18c, Comparative Examples 1c to 12c: Any of the ArF resins (i) to (vi) obtained in Synthesis Examples 1 to 6 above was mixed with the type of solvent shown in Tables 7 and 8 to prepare resist compositions having the active ingredient (ArF resin) concentration shown in Tables 7 and 8. The prepared resist compositions were then spin-coated onto silicon wafers at 3000 rpm to form coatings, and the coatings were pre-baked at 90°C for 60 seconds to form resist films. The film thicknesses of five arbitrarily selected locations on the resist film were measured, and the average film thickness of the five locations was calculated as the average film thickness. The results are shown in Tables 7 and 8.

[0134]

[0135]

[0136] Tables 7 and 8 show that the resist compositions prepared in Examples 1c to 18c are capable of forming thicker resist films than the resist compositions of Comparative Examples 1c to 12c having the same resin concentration.

[0137] Example 1d, Comparative Example 1d Resist Performance The following resist performance evaluation was carried out using the resin (ii), and the results are shown in Table 9.

[0138] (Preparation of Resist Composition) Resist compositions were prepared according to the formulations shown in Table 9. Of the components in the resist compositions in Table 9, the acid generator (C) and solvent used were as follows. Acid generator (C) P-1: Triphenylsulfonium trifluoro-1-butanesulfonate (Sigma-Aldrich) Solvent S-1: Methyl 2-hydroxyisobutyrate (Mitsubishi Gas Chemical Company, Inc.) S-1: Propylene glycol monomethyl ether acetate (Kanto Chemical Co., Inc.)

[0139] (Method for Evaluating Resist Performance of Resist Composition) A uniform resist composition was spin-coated onto a clean silicon wafer and then pre-exposure baked (PB) on a hot plate at 90°C to form a 50 nm thick resist film. The resulting resist film was irradiated with an electron beam using an electron beam lithography system (ELS-7500, manufactured by Elionix Co., Ltd.) with a 1:1 line-and-space setting at 500 nm intervals. After irradiation, the resist film was heated at 90°C for 90 seconds and immersed in an alkaline developer containing 2.38% by mass of tetramethylammonium hydroxide (TMAH) for 60 seconds for development. The resist film was then washed with ultrapure water for 30 seconds and dried to form a resist pattern. The lines and spaces of the formed resist pattern were observed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation) to evaluate the reactivity of the resist composition upon electron beam irradiation.

[0140] For resist pattern evaluation, both Example 1d and Comparative Example 1d were irradiated with an electron beam in a 1:1 line-and-space configuration with 500 nm spacing, resulting in good resist patterns. Furthermore, the film thickness of the resist pattern was thick in Example 1d, and it was confirmed that it had sufficient etching resistance for transferring the resist pattern. On the other hand, the film thickness of Comparative Example 1d was thin, and it was confirmed that it did not have the etching resistance required for pattern transfer.

[0141] In this way, when a resist composition satisfying the requirements of this embodiment is used, a more favorable resist pattern shape can be obtained than when the resist composition of Comparative Example 1d, which does not satisfy these requirements, is used. As long as the requirements of this embodiment are satisfied, resist compositions other than those described in the examples also exhibit the same effects.

[0142] [Resist Compositions Comprising ArF Resist Resins and Acid Generators] Resist compositions were prepared according to the formulations shown in Tables 10 and 11, and the solubility of the ArF resins (i) to (v) and acid generators (i) to (iv) used as raw materials shown in Tables 10 and 11 was evaluated. <Solvents> HBM: methyl 2-hydroxyisobutyrate (manufactured by Mitsubishi Gas Chemical Company, Inc.) αMBM: methyl α-methoxyisobutyrate (synthesized with reference to US2014 / 0275016) αFBM: methyl α-formyloxyisobutyrate (synthesized with reference to WO2020 / 004467) αABM: methyl α-acetyloxyisobutyrate (synthesized with reference to WO2020 / 004466) 3HBM: methyl 3-hydroxyisobutyrate (manufactured by Tokyo Chemical Industry Co., Ltd.) PGME: 1-methoxy-2-propanol (manufactured by Sigma-Aldrich) <Resins> Resins having the following compositions (molecular weights) were synthesized by the method described above. (i) EADM / NML = 18 / 82 (Mn = 3750) (ii) MADM / NML = 25 / 75 (Mn = 2740) (iii) MADM / GBLM = 25 / 75 (Mn = 3770) (iv) MADM / NML / HADM = 42 / 33 / 25 (Mn = 7260) (v) Copolymer having structural units of hydroxystyrene / t-butyl acrylate / styrene = 3 / 1 / 1 (molar ratio) (manufactured by Maruzen Petrochemical Co., Ltd., Mw = 12,000) <Acid generator> (i) WPAG-336 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (ii) WPAG-367 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (iii) WPAG-145 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (iv) Triphenylsulfonium Trifluoro-1-butanesulfonate (Sigma-Aldrich)

[0143] Resins of the types shown in Table 10 were added to solvents of the types shown in Table 10 so that the resin concentration was 15 wt %, and acid generators of the types shown in Table 10 were added so that the acid generator concentration was 1 wt %, to prepare resist compositions of Examples A1-1 to A1-4 and Comparative Example A1-1. After stirring at room temperature for 24 hours, the state was visually evaluated according to the following criteria. Rating S: Dissolved (clear solution confirmed visually) Rating A: Almost dissolved (almost clear solution confirmed visually) Rating C: Insoluble (cloudy solution confirmed visually)

[0144] The resins shown in Table 11 were added to the solvents shown in Table 11 so that the resin concentration was 40 wt %, and the acid generators shown in Table 11 were added so that the acid generator concentrations were the specified concentrations, to prepare resist compositions of Examples A2-1a to A2-5d and Comparative Example A2-1. After stirring at room temperature for 1 hour, the state was visually evaluated according to the following criteria: Rating S: 5 wt % dissolved (clear solution confirmed visually) Rating A: 1 wt % dissolved (clear solution confirmed visually) Rating C: 1 wt % insoluble (cloudy solution confirmed visually) The results are shown in Tables 10 and 11.

[0145] Table 10 shows that the resist compositions prepared in Examples A1-1 to A1-5 have superior resin solubility compared to the resist composition of Comparative Example A1-1, and that a variety of resist compositions can be prepared. In particular, resist compositions in which the solvent (B) contains αFBM as the solvent (B2) exhibit high solubility in any resin and are therefore preferably used.

[0146] Table 11 shows that the resist compositions prepared in Examples A2-1a to A2-5d have superior solubility for acid generators compared to the resist composition of Comparative Example A2-1, and that resist compositions can be prepared using any acid generator. In particular, resist compositions in which the solvent (B) contains αMBM, αFBM, or 3HBM as the solvent (B2) exhibit high solubility for any acid generator and are therefore preferably used.

[0147] [Resist Compositions Containing KrF Resins] A copolymer (manufactured by Maruzen Petrochemical Co., Ltd., Mw = 12,000) having structural units of hydroxystyrene / t-butyl acrylate / styrene = 3 / 1 / 1 (molar ratio) was mixed with the solvent type shown in Table 12 to prepare resist compositions with the active ingredient (KrF resin) concentration shown in Table 12. The prepared resist compositions were then spin-coated at 1500 rpm onto silicon wafers to form coatings, which were then pre-baked at 140°C for 60 seconds to form resist films. The film thickness was measured at five arbitrarily selected locations on the resist film, and the average value of the film thicknesses at those five locations was calculated as the average film thickness to evaluate the film thickness. Furthermore, the difference between the maximum and minimum film thicknesses was divided by the average value to evaluate the film uniformity. The results are shown in Table 12. Film thickness: Evaluation A: 20 μm or more Evaluation B: 15 μm or more and less than 20 μm Evaluation C: less than 15 μm Film uniformity: Evaluation A: less than 15 Evaluation B: 15 or more and less than 30 Evaluation C: 30 or more

[0148]

[0149] Table 12 shows that the resist compositions prepared in Examples A3-1a to A3-5c are capable of forming thicker resist films than the resist compositions of Comparative Examples A3-1a to A3-1b. In particular, resist compositions in which the solvent (B) contains αMBM, αFBM, 3HBM, or PGME as the solvent (B2) are all suitable for use, as they exhibit excellent film uniformity. Furthermore, resist compositions containing αFBM are suitable for use, as they can achieve a film thickness of 20 μm or more when the resin concentration is 40 wt%. Furthermore, resist compositions containing αMBM are suitable for use, as they can achieve a resin concentration of 45 wt% and a film thickness of 20 μm or more.

[0150] <Evaluation of In-Plane Uniformity of Resist Film> The KrF resin (a copolymer (manufactured by Maruzen Petrochemical Co., Ltd., Mw = 12,000) having structural units of hydroxystyrene / t-butyl acrylate / styrene = 3 / 1 / 1 (molar ratio)) was mixed with the type of solvent shown in Table 13 to prepare resist compositions with the active ingredient (KrF resin) concentration shown in Table 13. Using the prepared resist composition, a coating film was formed on a silicon wafer with a main spin of 1200 rpm, and the coating film was pre-baked at 110°C for 90 seconds to form a resist film with an average thickness of 7.2 μm. The film thickness was measured at 50 points at 3 mm intervals in the diameter direction of the resist film. The in-plane uniformity was evaluated by dividing three times the standard deviation of the film thickness by the average film thickness to calculate the film thickness unevenness 3σ. The results are shown in Table 13. In-plane uniformity: Evaluation A: 3σ≦less than 0.02 Evaluation B: 0.02 or more and less than 0.04 Evaluation C: 0.04 or more

[0151] <Resist Performance> The following resist performance evaluation was carried out using the resin (ii) (MADM / NML=25 / 75), and the results are shown in Table 14. Pattern evaluation: Evaluation S: A rectangular resist pattern was formed Evaluation A: A roughly rectangular resist pattern was formed Evaluation C: A rectangular resist pattern was not formed Pattern film thickness: Evaluation A: The film had the etching resistance required for pattern transfer Evaluation C: The film did not have the etching resistance required for pattern transfer

[0152] (Preparation of Resist Composition) Resist compositions were prepared according to the formulations shown in Table 14. Of the components of the resist compositions in Table 14, the acid generator (C) and solvent used were as follows: Acid Generator (C) P-1: triphenylsulfonium trifluoro-1-butanesulfonate (Sigma-Aldrich)

[0153] (Method for Evaluating Resist Performance of Resist Composition) A uniform resist composition was spin-coated onto a clean silicon wafer and then pre-exposure baked (PB) on a hot plate at 90°C to form a 50 nm thick resist film. The resulting resist film was irradiated with an electron beam using an electron beam lithography system (ELS-7500, manufactured by Elionix Co., Ltd.) with a 1:1 line-and-space setting at 500 nm intervals. After irradiation, the resist film was heated at 90°C for 90 seconds and immersed in an alkaline developer containing 2.38% by mass of tetramethylammonium hydroxide (TMAH) for 60 seconds for development. The resist film was then washed with ultrapure water for 30 seconds and dried to form a resist pattern. The lines and spaces of the formed resist pattern were observed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation) to evaluate the reactivity of the resist composition upon electron beam irradiation.

[0154] Regarding resist pattern evaluation, good resist patterns were obtained by irradiating electron beams in a 1:1 line-and-space configuration with 500 nm spacing in both Examples A5-1 to A5-6b and Comparative Example A5. Furthermore, with regard to the film thickness of the resist pattern, it was confirmed that Examples A5-1 to A5-6b had thick film thicknesses and provided sufficient etching resistance for transferring the resist pattern. On the other hand, it was confirmed that Comparative Example A5 had thin film thicknesses and did not provide the etching resistance required for pattern transfer. In particular, the resist composition in which the solvent (B) contains 3HBM as the solvent (B2) provided rectangular resist patterns, and is therefore suitable for use due to its excellent pattern transfer performance.

[0155] In this way, when a resist composition that satisfies the requirements of this embodiment is used, a more favorable resist pattern shape can be obtained than when the resist composition of Comparative Example A5 is used, which does not satisfy these requirements.

[0156] As long as the requirements of this embodiment are met, resist compositions other than those described in the examples will also exhibit the same effects.

Claims

1. A resist composition containing a resin (A) and a solvent (B) containing a compound (B1) represented by the following general formula (b-1), wherein the content of the active ingredient based on the total amount of the resist composition is 45% by mass or less. 【Chemical Formula 1】 [In the above formula (b-1), R １ is an alkyl group having 1 to 10 carbon atoms. ]

2. The resist composition according to claim 1, further containing at least one additive (C) selected from a photosensitizer and an acid generator.

3. R in the general formula (b-1) １ is a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, or a t-butyl group. The resist composition according to claim 1.

4. R in the general formula (b-1) １ is an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, or a t-butyl group. The resist composition according to claim 1.

5. The resist composition according to claim 1, wherein the solvent (B) contains a solvent (B2) other than the compound (B1).

6. The resist composition according to claim 5, wherein the solvent (B) contains, as the solvent (B2), one or more selected from the group consisting of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acyloxyisobutyrate, and methyl 3-hydroxyisobutyrate.

7. The resist composition according to claim 5, wherein the solvent (B) contains, as the solvent (B2), one or more selected from the group consisting of methyl α-methoxyisobutyrate, methyl α-formyloxyisobutyrate, methyl α-acyloxyisobutyrate, methyl 3-hydroxyisobutyrate, and 1-methoxy-2-propanol.

8. The resist composition according to claim 5, wherein the solvent (B2) is contained in an amount of 100% by mass or less based on the total amount (100% by mass) of the compound (B1).

9. The resist composition according to claim 8, wherein the solvent (B2) is contained in an amount of less than 70% by mass based on the total amount (100% by mass) of the compound (B1).

10. The resist composition according to claim 8, wherein the solvent (B2) is contained in an amount of 0.0001% by mass or more based on the total amount (100% by mass) of the compound (B1).

11. The resist composition according to claim 5, wherein the solvent (B2) is contained in an amount of less than 100% by mass based on the total amount (100% by mass) of the resist composition.

12. The resist composition according to claim 1, wherein the resin (A) contains a novolak resin (A1).

13. The resist composition according to claim 1, wherein the resin (A) contains a resin (A2) having at least one of a structural unit (a2-1) derived from a phenolic hydroxyl group-containing compound and a structural unit (a2-2) capable of decomposing upon the action of an acid, a base, or heat to form an acidic functional group.

14. The resist composition according to claim 1, wherein the resin (A) contains a resin (A3) having a structural unit (a3-1) having an adamantane structure.

15. The resist composition according to claim 14, wherein the resin (A3) is a copolymer having a structural unit (a3-2) having a lactone structure together with the structural unit (a3-1).

16. The resist composition according to claim 14, wherein the content of the structural unit (a3-1α) having an adamantane structure substituted with a hydroxy group is less than 50 mol% with respect to the total amount of the structural units of the resin (A3).

17. The resist composition according to claim 1, wherein the resin (A) contains a resin (A4) having any two or more of a structural unit (a2-1) derived from a phenolic hydroxyl group-containing compound, a structural unit (a2-2) capable of forming an acidic functional group by decomposition by the action of an acid, a base or heat, a structural unit (a3-1) having an adamantane structure, and a structural unit (a3-2) having a lactone structure.

18. Step (1): A step of applying the resist composition according to any one of claims 1 to 17 onto a substrate to form a coating film. Step (2): A step of performing a heat treatment after step (1), and Step (3): A step of forming a resist pattern, which is a resist film forming method.

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