Resist auxiliary film composition, and pattern forming method using said composition

Abstract

According to the present invention, it is possible to provide a resist auxiliary film composition comprising: a resin (A); and a solvent (B) containing a compound (B1) represented by general formula (b-1), wherein the content of an active ingredient is at most 45 mass% with respect to the total amount of the resist auxiliary film composition. (In formula (b-1), R1 is a C1-C10 alkyl group.)

Description

Resist auxiliary film composition and pattern forming method using said composition

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

[0002] In recent years, with the increasing integration and speed of semiconductor devices, there has been a demand for finer pattern rules. In light of this, in lithography, which is currently used as a general-purpose technology using optical exposure, various technological developments have been carried out to achieve finer and more accurate pattern processing using the light source used.

[0003] As a light source for lithography used in resist pattern formation, light exposure using a mercury lamp's g-line (436 nm) or i-line (365 nm) light source is widely used in areas with low integration. On the other hand, in areas with high integration and requiring finer patterning, lithography using shorter wavelength KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) has also been put to practical use, and in the most advanced generation requiring even finer patterning, extreme ultraviolet (EUV, 13.5 nm) lithography is approaching practical use. In addition, various resist auxiliary films are used to improve the performance of photoresists in order to improve finer patterning.

[0004] With the application of KrF excimer lasers and ArF excimer lasers, the effects of diffuse reflection of actinic rays from the substrate and standing waves have become major problems, and a method of providing an anti-reflective coating (Bottom Anti-Reflective Coating, BARC) as a resist underlayer film that serves to prevent reflection between the photoresist and the substrate to be processed has become widely adopted.

[0005] Known anti-reflective coatings include inorganic anti-reflective coatings made of titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, α-silicon, etc., and organic anti-reflective coatings made of light-absorbing substances and polymer compounds. While the former require equipment such as a vacuum deposition apparatus, CVD apparatus, or sputtering apparatus for film formation, the latter is advantageous in that it does not require special equipment, and has been the subject of extensive investigation.

[0006] Examples of such antireflection films include an acrylic resin type antireflection film having a hydroxyl group, which is a crosslinking reactive group, and a light-absorbing group in the same molecule (see Patent Document 1), and a novolac resin type antireflection film having a hydroxyl group, which is a crosslinking reactive group, and a light-absorbing group in the same molecule (see Patent Document 2).

[0007] Desirable physical properties of an organic antireflective coating material include high absorbance for light and radiation, no intermixing with the photoresist layer (insolubility in resist solvents), no low-molecular-weight diffusion of substances from the antireflective coating material into the topcoat resist during application or heat drying, and a higher dry etching rate than the photoresist (see Non-Patent Document 1).

[0008] In device fabrication processes using EUV lithography, problems arise such as the adverse effects of the underlying substrate and EUV causing the pattern of the resist for EUV lithography to have a footing or undercut shape, making it impossible to form a resist pattern with a good straight shape, and the sensitivity to EUV is low and sufficient throughput cannot be obtained. Therefore, although a resist underlayer film (anti-reflective film) with anti-reflection properties is not necessary in the EUV lithography process, a resist underlayer film for EUV lithography is needed that can reduce these adverse effects, form a resist pattern with a good straight shape, and improve resist sensitivity.

[0009] Furthermore, since a resist is coated on top of a resist underlayer film for EUV lithography after it is formed, essential properties of the resist underlayer film are that it does not intermix with the resist layer (it is insoluble in a resist solvent) and that it has excellent adhesion to the resist, similar to antireflective coatings.

[0010] Furthermore, in the generation using EUV lithography, resist pattern widths will become extremely fine, and therefore thinner resists for EUV lithography are desired. Therefore, it is necessary to significantly reduce the time required for the step of removing the organic antireflective coating by etching, and there is a demand for a resist underlayer film for EUV lithography that can be used in a thin film, or a resist underlayer film for EUV lithography that has a large etching rate selectivity relative to the resist for EUV lithography.

[0011] Furthermore, as resist patterns become thinner, the ratio of pattern height to pattern linewidth (aspect ratio) increases in the single-layer resist method, a typical resist pattern formation method, and it is well known that this causes pattern collapse during development due to the surface tension of the developer. Therefore, it is known that a multilayer resist method, in which a pattern is formed by stacking films with different dry etching characteristics, is superior for forming high-aspect-ratio patterns on uneven substrates. Two-layer resist methods have been developed, combining a photoresist layer made of a silicon-containing photosensitive polymer with an underlayer made of an organic polymer, such as a novolac polymer, whose main constituent elements are carbon, hydrogen, and oxygen (see, for example, Patent Document 3). Another three-layer resist method has been developed, combining a photoresist layer made of an organic photosensitive polymer used in the single-layer resist method with an intermediate layer made of a silicon-based polymer or silicon-based CVD film and an underlayer made of an organic polymer (see, for example, Patent Document 4).

[0012] In this three-layer resist method, first, a photoresist layer pattern is transferred to a silicon-containing intermediate layer using a fluorocarbon dry etching gas, and then the pattern is used as a mask to transfer the pattern to an organic underlayer film mainly composed of carbon and hydrogen by dry etching using an oxygen-containing gas, and then the pattern is formed on a substrate to be processed by dry etching using this as a mask. However, in semiconductor device manufacturing processes for the 20 nm generation and later, when this organic underlayer film pattern is used as a hard mask to transfer the pattern to a substrate to be processed by dry etching, the underlayer film pattern has been observed to become twisted or bent.

[0013] Amorphous carbon (CVD-C) films, fabricated by CVD using methane, ethane, acetylene, or other gases, are commonly used as carbon hard masks on substrates. These CVD-C films are known to minimize the amount of hydrogen atoms present in the film, making them extremely effective at preventing the aforementioned pattern distortion and warping. However, due to the nature of the CVD process, it is difficult to fill uneven surfaces in the underlying substrate. Therefore, when a substrate with uneven surfaces is filled with a CVD-C film and then patterned with photoresist, uneven surfaces are created on the photoresist coating due to the unevenness of the substrate, resulting in uneven photoresist thickness and resulting in poor focus tolerance and poor pattern shape during lithography.

[0014] On the other hand, when the underlayer film used as a carbon hard mask is formed directly on the substrate to be processed by spin coating, it is known to have the advantage of being able to fill in the unevenness of the substrate. Planarizing the substrate with this underlayer film material reduces film thickness variations of the silicon-containing intermediate layer and photoresist formed on it, expanding the focus tolerance of lithography and enabling the formation of normal patterns.

[0015] Therefore, there is a need for a method for forming an underlayer film material (spin-on carbon film material) and an underlayer film (spin-on carbon film) that can be formed by a spin coating method, which has high etching resistance when dry etching a substrate to be processed and can form a film with high flatness on the substrate to be processed.

[0016] Generally, materials with a high carbon content are used for spin-on carbon films. The use of such materials with a high carbon content in resist underlayer films improves etching resistance during substrate processing, thereby enabling more accurate pattern transfer. Phenol novolac resins are well known as such spin-on carbon films (see, for example, Patent Document 5). It is also known that spin-on carbon films formed from resist spin-on carbon film compositions containing acenaphthylene-based polymers exhibit excellent properties (see, for example, Patent Document 6).

[0017] US Patent No. 5,919,599 US Patent No. 5,693,691 JP 2000-143937 A JP 2001-40293 A JP 2010-15112 A JP 2005-250434 A

[0018] Proc. SPIE, Vol. 3678, 174-185 (1999).

[0019] As described above, the photoresist auxiliary film 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 auxiliary film materials that can form resist auxiliary films suitable for manufacturing various devices.

[0020] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a resist auxiliary film composition containing 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. That is, the present invention is as follows: [1] A resist auxiliary film 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 is 45 mass% or less based on the total amount of the resist auxiliary film composition: [In the above formula (b-1), R １ is an alkyl group having 1 to 10 carbon atoms.] [2] The resist auxiliary film 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 auxiliary film 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 auxiliary film composition according to any one of [1] to [4] above, wherein the solvent (B) comprises a solvent (B2) other than the compound (B1). [6] The resist auxiliary film composition according to [5] above, wherein the solvent (B) comprises, 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 auxiliary film composition according to [5] above, wherein the solvent (B) comprises, 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 auxiliary film composition according to any one of [5] to [7] above, wherein the solvent (B2) accounts for 100% by mass or less, based on the total amount (100% by mass) of the compound (B1). [9] The resist auxiliary film composition according to [8] above, wherein the solvent (B2) accounts for 0.0001% by mass or more, based on the total amount (100% by mass) of the compound (B1).

[10] The resist auxiliary film composition according to any one of [5] to [9] above, wherein the solvent (B2) accounts for less than 100% by mass, based on the total amount (100% by mass) of the resist auxiliary film composition.

[11] The resist auxiliary film composition according to any one of [1] to

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

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

[10] above, wherein the resin (A) comprises an ethylenically unsaturated resin (A2).

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

[10] above, wherein the resin (A) comprises a high-carbon resin (A3).

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

[10] above, wherein the resin (A) comprises a silicon-containing resin (A4).

[15] The resist auxiliary film composition according to any one of [1] to

[14] above, wherein the resist auxiliary film is a resist underlayer film.

[16] The resist auxiliary film composition according to any one of [1] to

[14] above, wherein the resist auxiliary film is a resist intermediate film.

[17] A method for forming a pattern, comprising: a step (A-1) of forming a resist underlayer film on a substrate using the resist auxiliary film composition according to

[15] above; a step (A-2) of forming at least one photoresist layer on the resist underlayer film; and a step (A-3) of irradiating a predetermined region of the photoresist layer with radiation and developing the photoresist layer after the step (A-2).

[18] A method for forming a pattern, comprising: a step (B-1) of forming a resist underlayer film on a substrate using the resist auxiliary film composition described in

[15] above; a step (B-2) of forming a resist intermediate layer film on the resist underlayer film; a step (B-3) of forming at least one photoresist layer on the resist intermediate layer film; and, after the step (B-3), a step (B-4) of irradiating a predetermined region of the photoresist layer with radiation and developing it to form a resist pattern. After the step (B-4), a step (B-5) of etching the resist intermediate layer film using the resist pattern as a mask, etching the resist underlayer film using the obtained resist intermediate layer film pattern as an etching mask, and etching the substrate using the obtained resist underlayer film pattern as an etching mask, thereby forming a pattern on the substrate.

[19] A pattern forming method comprising: a step (B-1) of forming a resist underlayer film on a substrate; a step (B-2) of forming a resist intermediate layer film on the resist underlayer film using the resist auxiliary film composition described in

[16] above; a step (B-3) of forming at least one photoresist layer on the resist intermediate layer film; and, after the step (B-3), a step (B-4) of irradiating a predetermined region of the photoresist layer with radiation and developing it to form a resist pattern; and, after the step (B-4), a step (B-5) of etching the resist intermediate layer film using the resist pattern as a mask, etching the resist underlayer film using the obtained resist intermediate layer film pattern as an etching mask, and etching the substrate using the obtained resist underlayer film pattern as an etching mask, thereby forming a pattern on the substrate.

[0021] A resist auxiliary composition according to a preferred embodiment of the present invention is capable of forming a resist auxiliary 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.

[0022] [Resist auxiliary film composition] The resist auxiliary film 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)") containing a compound (B1) represented by general formula (b-1). In the present invention, the term "resist auxiliary film" refers to any film used as an upper layer of a resist or a lower layer of a resist, including, for example, a resist top layer film, a resist middle layer film, and a resist underlayer film. Furthermore, the resist auxiliary film 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 auxiliary film composition of the present invention, the content of the active ingredient is limited to 45% by mass or less based on the total amount (100% by mass) of the resist auxiliary film composition. In this specification, the term "active ingredient" refers to the components contained in the resist auxiliary film 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 promoters, antihalation agents, storage stabilizers, defoamers, and shape modifiers. Generally, for example, application as an etching mask requires the formation of a thick resist auxiliary film. However, when a resist auxiliary film composition with a low resin content is used, the formation of a thick resist auxiliary film becomes difficult. In contrast, by using a compound represented by general formula (b-1) as a solvent, the resist auxiliary film composition of the present invention can be used as a photoresist auxiliary film material capable of forming a thick resist auxiliary film, even when the content of active ingredients, including the resin, is reduced to 45% by mass or less. Furthermore, since the resist auxiliary film 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.

[0023] In the resist auxiliary film 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 auxiliary film 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 auxiliary film composition. The content of the active ingredient can be determined in any combination by appropriately selecting from the above-mentioned upper and lower limit options.

[0024] In the resist auxiliary film composition of one embodiment of the present invention, from the viewpoint of using the composition as a photoresist auxiliary film material capable of forming a thick resist auxiliary film, the content of component (A) among the active ingredients 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 the active ingredients contained in the resist auxiliary film composition.

[0025] The resist auxiliary film composition of one embodiment of the present invention may contain other components in addition to the above components (A) to (C) depending on the application. However, in the resist auxiliary film 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 auxiliary film composition. Hereinafter, the details of each component contained in the resist auxiliary film composition of one embodiment of the present invention will be described.

[0026] <Component (A): Resin> The resin (A) contained in the resist auxiliary film composition of one embodiment of the present invention is not particularly limited, and examples thereof include resins used for anti-reflective coatings for KrF excimer lasers or ArF excimer lasers, or photoresist underlayer film materials for EUV lithography, high-carbon-concentration resins for spin-on carbon films used in bilayer and trilayer resist methods, silicon-containing resins for spin-on glass films used in bilayer and trilayer resist methods, and even resins used for upper layer films of photoresists intended for contamination prevention, removal of unnecessary wavelengths of light, or waterproofing for immersion exposure. The resin (A) can be appropriately selected depending on the application. In this specification, the term "resin" refers not only to polymers having specific structural units, but also to compounds having specific structures. The weight-average molecular weight (Mw) of the resin used in one embodiment of the present invention is preferably 500 to 50,000, more preferably 1,000 to 40,000, and even more preferably 1,000 to 30,000.

[0027] In the resist auxiliary film composition of the present invention, the content of component (A) may be set appropriately depending on the application, such as 45% by mass or less, 42% by mass or less, 40% by mass or less, 35% 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, based on the total amount (100% by mass) of the resist auxiliary film composition. The lower limit of the content of component (A) 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, based on the total amount (100% by mass) of the resist auxiliary film composition. The content of component (A) can be determined in any combination by appropriately selecting from the above-mentioned upper and lower limit values.

[0028] The resist auxiliary film composition is suitable for use as an anti-reflective film for KrF excimer laser or ArF excimer laser, or as a photoresist underlayer film material for EUV lithography, or as a spin-on carbon film for use in two-layer resist method or three-layer resist method, or as a spin-on glass film for use in three-layer resist method.For example, when used as an anti-reflective film for KrF excimer laser or ArF excimer laser, or as a photoresist underlayer film material for EUV lithography, resin (A) preferably comprises novolac resin (A1) or ethylenically unsaturated resin (A2).In addition, when used as a spin-on carbon film for use in two-layer resist method or three-layer resist method, it preferably comprises high-carbon resin (A3), and when used as a spin-on glass film for use in three-layer resist method, it preferably comprises silicon-containing resin (A4).

[0029] The resin (A) contained in the resist auxiliary film 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.

[0030] [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 2013-024779, and WO 2015-137486.

[0031] 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.

[0032] Examples of aldehydes include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropionaldehyde, β-phenylpropionaldehyde, benzaldehyde, 4-biphenylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, 3,4-dimethylbenzaldehyde, p-n-propylbenzaldehyde, p-n-butylbenzaldehyde, and terephthalaldehyde. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, acetophenone, diphenyl ketone, etc. These aldehydes and ketones may be used alone or in combination of two or more.

[0033] 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.

[0034] 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.).

[0035] 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.

[0036] [Ethylenically Unsaturated Resin (A2)] The ethylenically unsaturated resin (A2) used in one embodiment of the present invention is not particularly limited, and known resins can be used, but it may be a resin (A2a) 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 be decomposed by the action of an acid, a base, or heat to form an acidic functional group, or it may be a copolymer that has both the structural unit (a2-1) and the structural unit (a2-2). By using a resin that has at least one of the structural unit (a2-1) and the structural unit (a2-2), it is possible to increase the solubility of the compound (B1).

[0037] In the resin (A2a) 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 (A2a) 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.

[0038] Furthermore, when the resin (A2a) 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] As described above, the resin (A2a) 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.

[0044] 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).

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The resin (A2a) 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 (A2a) and also corresponds to the resin (A2b) described below.

[0049] Furthermore, the resin (A2a) 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.

[0050] The weight average molecular weight (Mw) of the resin (A2a) 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.

[0051] The resin (A2) used in one embodiment of the present invention may be a resin (A2b) having a structural unit (b2-1) having an adamantane structure, and preferably has a structural unit 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 that the resin (A2) be a copolymer having a structural unit (b2-2) having a lactone structure in addition to the structural unit (b2-1).

[0052] At least one of the hydrogen atoms bonded to a carbon atom that constitutes the adamantane structure of the structural unit (b2-1) 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 (b2-2) 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):

[0053]

[0054] 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.

[0055] In the resin (A2b) used in one embodiment of the present invention, the content of the structural unit (b2-1), that is, the structural unit (b2-1α) having an adamantane structure substituted with a hydroxy group, relative to the total amount (100 mol%) of structural units in the resin (A2b) 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%.

[0056] In one embodiment of the present invention, the structural unit (b2-1) is preferably a structural unit (b2-1-1) represented by the following formula (b2-1-i) or a structural unit (b2-1-2) represented by the following formula (b2-1-ii).

[0057]

[0058] 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:

[0059] In the above formula, *1 indicates the bonding position to the oxygen atom in the above formula (b2-1-i) or (b2-1-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.

[0060] In one embodiment of the present invention, the structural unit (b2-2) is preferably any one of the structural unit (b2-2-1) represented by the following formula (b2-2-i), the structural unit (b2-2-2) represented by the following formula (b2-2-ii), and the structural unit (b2-2-3) represented by the following formula (b2-2-iii):

[0061]

[0062] 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:

[0063] In the above formula, *1 indicates the bonding position to the oxygen atom in the above formula (b2-2-i), (b2-2-ii), or (b2-2-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.

[0064] The resin (A2b) used in one embodiment of the present invention may contain other structural units in addition to the structural units (b2-1) and (b2-2). 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 for resin (A2a).

[0065] In the resin (A2b) used in one embodiment of the present invention, the combined amount of the structural units (b2-1) and (b2-2) 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 (A2b).

[0066] The weight average molecular weight (Mw) of the resin (A2b) 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 (A2b) 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.

[0067] Resin (A2) used in one embodiment of the present invention is a resin (A2c) 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 (b2-1) having an adamantane structure, and a structural unit (b2-2) having a lactone structure (excluding resin (A2a) and resin (A2b).) Resin (A2c) is not particularly limited, and known resins are used, for example, the resins listed in the book "Lithography Technology: Its 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 applied.

[0068] The weight average molecular weight (Mw) of the resin (A2c) used in one embodiment of the present invention is preferably 500 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 (A2c) 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.

[0069] [High-carbon resin (A3)] The high-carbon resin (A3) used in one embodiment of the present invention is a resin in which the weight of carbon atoms contained in the resin exceeds 60% of the weight of all elements. Among them, a resin in which the weight of carbon atoms exceeds 70% is preferred, more preferably a resin in which the weight of carbon atoms exceeds 80%, and even more preferably a resin in which the weight of carbon atoms exceeds 90%. Specific examples of the high-carbon resin (A3) are not particularly limited, but include known resins described in, for example, WO 2020 / 145406.

[0070] 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.

[0071] [Silicon-containing resin (A4)] The silicon-containing resin (A4) used in one embodiment of the present invention is not particularly limited as long as it is a resin containing a silicon atom, but examples thereof include known resins described in JP-A Nos. 2007-226170 and 2007-226204.

[0072] 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.

[0073] <Component (B): Solvent> The resist auxiliary film composition of one embodiment of the present invention contains a solvent (B) containing a compound (B1) represented by the following general formula (b-1): The compound (B1) may be used alone or in combination of two or more types:

[0074]

[0075] 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.

[0076] 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.

[0077] The resist auxiliary film composition of one embodiment of the present invention may further contain a solvent (B2) other than the compound (B1) as component (B). 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.

[0078] However, from the viewpoint of using a photoresist auxiliary film material capable of forming a thick resist auxiliary film, the content of compound (B1) in component (B) in the resist auxiliary film composition of the present invention 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 auxiliary film composition.

[0079] In one embodiment of the present invention, component (B) used preferably contains, as 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, from the viewpoint of solubility of the acid generator used in the resist auxiliary film composition. The inclusion of methyl α-methoxyisobutyrate is preferred from the viewpoint of solubility of the resin used in the resist auxiliary film 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 auxiliary film composition and thickening of the resist film. The inclusion of methyl 3-hydroxyisobutyrate is preferred from the viewpoint of obtaining a coating film with good surface condition upon high-temperature baking. The inclusion of 1-methoxy-2-propanol is preferred from the viewpoint of obtaining a coating 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 α-acetyloxyisobutyrate, 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).

[0080] 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 a moderate 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 auxiliary film composition, it is preferably 0.0001% by mass or more, from the viewpoint of improving the solubility of the active ingredient of the resist auxiliary film composition, it is more preferably 0.001% by mass or more, and from the viewpoint of suppressing defects in the resist auxiliary film, it is even more preferably 0.01% by mass or more.

[0081] 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 auxiliary film composition, from the viewpoint 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 viewpoint of improving the storage stability of the resist auxiliary film composition, the content is preferably 0.0001% by mass or more, from the viewpoint of improving the solubility of the active ingredients of the resist auxiliary film composition, more preferably 0.001% by mass or more, and from the viewpoint of suppressing defects in the resist auxiliary film, even more preferably 0.01% by mass or more.

[0082] 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 viewpoint of improving productivity by shortening the drying time of the resist auxiliary film 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, 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 auxiliary film composition, the content is preferably 0.0001% by mass or more, from the viewpoint of improving the solubility of the active ingredients of the resist auxiliary film composition, more preferably 0.001% by mass or more, and from the viewpoint of suppressing defects in the resist auxiliary film, even more preferably 0.01% by mass or more.

[0083] From the viewpoint of in-plane uniformity of the coating film, the content of 1-methoxy-2-propanol is preferably 1 to 98 mass%, more preferably 16 to 98 mass%, based on the total amount (100 mass%) of the resist auxiliary film composition, and is preferably 1 to 99 mass%, more preferably 30 to 99 mass%, based on the total amount (100 mass%) of compound (B1).

[0084] 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.

[0085] In the resist auxiliary film 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 auxiliary film composition. Furthermore, 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 auxiliary film composition. The content of component (B) can be determined in any combination by appropriately selecting from the above-mentioned upper limit and lower limit options.

[0086] <Component (C): Additive Selected from Photosensitizer and Acid Generator> The resist auxiliary film 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 in combination of two or more. In the resist auxiliary film composition of one embodiment of the present invention, the content of component (C) 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, per 100 parts by mass of resin (A) contained in the resist auxiliary film composition. The photosensitizer and acid generator contained as component (C) are described below.

[0087] [Photosensitizer] The photosensitizer that can be selected as component (C) is not particularly limited as long as it is generally used as a photosensitive component in a resist auxiliary film composition. Those used in resist compositions can also be used. The photosensitizer may be used alone or in combination of two or more.

[0088] 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 suitable photosensitizers include benzophenones, hydroxyphenylalkanes such as 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, as the photosensitizer used in one embodiment of the present invention, a commercially available product such as "DTEP-350" (diazonaphthoquinone-type photosensitizer, manufactured by Daito Chemiks Co., Ltd.) may also be used.

[0089] [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 heating or upon irradiation with radiation such as visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet light (EUV), X-ray, or ion beam. Specific examples of suitable acid generators include compounds represented by any of the following general formulas (c-1) to (c-8):

[0090] (Compound represented by general formula (c-1))

[0091] 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.

[0092] 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.

[0093] (Compound represented by general formula (c-2))

[0094] 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.

[0095] 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.

[0096] (Compound represented by general formula (c-3))

[0097] 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.

[0098] 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.

[0099] (Compound represented by general formula (c-4))

[0100] 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.

[0101] 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.

[0102] (Compound represented by general formula (c-5))

[0103] 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.

[0104] 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.

[0105] (Compound represented by general formula (c-6))

[0106] 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.

[0107] (Compounds represented by general formulas (c-7) and (c-8))

[0108] 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):

[0109]

[0110] 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.

[0111] 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.

[0112] <Other Additives> The resist auxiliary film composition of one embodiment of the present invention may contain components other than the above-described components (A) to (C). Examples of other components include one or more selected from 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 the resin (A) contained in the resist auxiliary film composition.

[0113] (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.

[0114] (Acid Diffusion Controller) The acid diffusion controller is an additive that has the effect of controlling the diffusion of the acid generated from the acid generator in the resist auxiliary film, thereby preventing undesirable chemical reactions. 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.

[0115] (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.

[0116] (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.

[0117] (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 produced. It is also an additive that absorbs light of a specific wavelength. 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.

[0118] (Surfactant) The surfactant is an additive that has the effect of improving the coatability and striation of the resist auxiliary film composition, the developability of the resist auxiliary film composition, 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.

[0119] (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.

[0120] (Other Components) In addition to the other components described above, the resist auxiliary film composition of one embodiment of the present invention may also contain dyes, pigments, adhesion aids, antihalation agents, storage stabilizers, antifoaming agents, shape improvers, etc.

[0121] [Pattern Forming Method] One embodiment of the present invention is a pattern forming method, which includes the steps of: (A-1) forming a resist underlayer film on a substrate using the resist auxiliary film composition of the present invention; (A-2) forming at least one photoresist layer on the resist underlayer film; and (A-3) irradiating a predetermined region of the photoresist layer with radiation and developing the photoresist layer after the step (A-2). As described above, the resist auxiliary film composition of one embodiment of the present invention is capable of forming a thick resist auxiliary film (here, a resist underlayer film) suitable for the manufacture of various devices, even though the content of active ingredients including a resin is limited to a predetermined value or less.

[0122] When the resist auxiliary film composition of this embodiment is used as a photoresist underlayer film material for a spin-on carbon film used in a two-layer resist method or a three-layer resist method, the process includes: a step (B-1) of forming a resist underlayer film using the resist auxiliary film composition of this embodiment; a step (B-2) of forming a resist intermediate layer film on the resist underlayer film; a step (B-3) of forming at least one photoresist layer on the resist intermediate layer film; a step (B-4) of irradiating a predetermined region of the photoresist layer with radiation and developing it to form a resist pattern; and a step (B-5) of etching the resist intermediate layer film using the resist pattern as a mask, etching the resist underlayer film using the obtained resist intermediate layer film pattern as an etching mask, and etching a substrate using the obtained resist underlayer film pattern as an etching mask, thereby forming a pattern on a substrate.

[0123] The resist underlayer film may be formed by any known method, as long as it is formed from the resist auxiliary film composition of the present embodiment. For example, the resist auxiliary film composition of the present embodiment may be applied to a substrate by a known coating method or printing method such as spin coating or screen printing, and then the organic solvent may be removed by volatilization or the like to form the resist underlayer film.

[0124] When forming the resist underlayer film, it is preferable to bake it in order to prevent mixing with the upper resist layer and to promote the crosslinking reaction. In this case, the baking temperature is not particularly limited, but is preferably in the range of 80 to 600°C, and more preferably 200 to 400°C. The baking time is also not particularly limited, but is preferably in the range of 10 to 300 seconds. The thickness of the resist underlayer film can be appropriately selected depending on the required performance, and is not particularly limited, but is usually preferably 3 to 20,000 nm, more preferably 10 to 15,000 nm, and even more preferably 50 to 1,000 nm.

[0125] After forming a resist underlayer film on a substrate, when the resist underlayer film is to be used as an anti-reflection film for KrF excimer laser or ArF excimer laser or as a photoresist underlayer film material for EUV lithography, it is preferable to form a single-layer resist layer thereon. In this case, known photoresist materials can be used to form this resist layer.

[0126] When a resist underlayer film is formed on a substrate and then used as a photoresist underlayer film material for a spin-on carbon film used in a two-layer resist method or a three-layer resist method, it is preferable to form a silicon-containing resist layer or a monolayer resist made of a normal hydrocarbon on the resist underlayer film in the two-layer process, or a silicon-containing intermediate layer and a silicon-free monolayer resist layer on the monolayer resist in the three-layer process. In this case, known photoresist materials can be used to form the resist layers.

[0127] From the viewpoint of oxygen gas etching resistance, silicon-containing resist materials for two-layer processes are preferably positive photoresist materials that use a silicon atom-containing polymer such as a polysilsesquioxane derivative or a vinylsilane derivative as a base polymer, and further contain an organic solvent, an acid generator, and optionally a basic compound, etc. Here, the silicon atom-containing polymer can be any known polymer used in this type of resist material.

[0128] A polysilsesquioxane-based intermediate layer is preferably used as the silicon-containing intermediate layer for the three-layer process. By providing the intermediate layer with the function of an anti-reflective coating, reflection tends to be effectively suppressed. For example, in a 193 nm exposure process, if a material containing many aromatic groups and having high substrate etching resistance is used as the resist underlayer film, the k value tends to be high and the substrate reflection tends to be high. However, by suppressing reflection with an intermediate layer, the substrate reflection can be reduced to 0.5% or less. Examples of intermediate layers with such anti-reflective effects include, but are not limited to, acid- or heat-crosslinkable polysilsesquioxanes into which phenyl groups or light-absorbing groups having silicon-silicon bonds have been introduced, and which are preferably used for 193 nm exposure.

[0129] Alternatively, an intermediate layer formed by a chemical vapor deposition (CVD) method can be used. Examples of intermediate layers that are highly effective as anti-reflection films and are produced by a CVD method include, but are not limited to, SiON films. Generally, forming an intermediate layer by a wet process such as spin coating or screen printing is more convenient and cost-effective than using a CVD method. The upper layer resist in a three-layer process may be either a positive or negative type, and the same resist as a commonly used single-layer resist can be used.

[0130] When forming a resist layer using the photoresist material, wet processes such as spin coating and screen printing are preferably used, as in the case of forming the resist underlayer film. After applying the resist material by spin coating or the like, pre-baking is typically performed, preferably at 80 to 180°C for 10 to 300 seconds. Subsequently, exposure, post-exposure baking (PEB), and development are performed according to conventional methods to obtain a resist pattern. The thickness of the resist film is not particularly limited, but is generally preferably 10 to 50,000 nm, more preferably 20 to 20,000 nm, and even more preferably 50 to 15,000 nm.

[0131] The exposure light may be appropriately selected depending on the photoresist material used, and generally includes high-energy rays with a wavelength of 300 nm or less, specifically excimer lasers with wavelengths of 248 nm, 193 nm, and 157 nm, soft X-rays with wavelengths of 3 to 20 nm, electron beams, X-rays, and the like.

[0132] The resist pattern formed by the above-described method is prevented from pattern collapse by the resist underlayer film of this embodiment. Therefore, by using the resist underlayer film of this embodiment, a finer pattern can be obtained, and the exposure dose required to obtain the resist pattern can be reduced.

[0133] Next, etching is performed using the obtained resist pattern as a mask. Gas etching is preferably used for etching the resist underlayer film in the two-layer process. As the gas etching, etching using oxygen gas is suitable. In addition to oxygen gas, inert gases such as He and Ar, CO, CO ２ , N.H. ３ , S.O. ２ , N ２ , NO ２ , H ２ It is also possible to add gases such as CO, CO2, etc. without using oxygen gas. ２ , N.H. ３ , N ２ , NO ２ , H ２ Gas etching can also be performed using only the gas, and the latter gas is particularly preferably used to protect the sidewalls of the pattern to prevent undercutting of the sidewalls.

[0134] On the other hand, gas etching is also preferably used for etching the intermediate layer in the three-layer process. The same gas etching as that described in the two-layer process can be applied. In particular, processing of the intermediate layer in the three-layer process is preferably performed using a fluorocarbon-based gas with the resist pattern as a mask. Then, as described above, the resist underlayer film can be processed by, for example, oxygen gas etching with the intermediate layer pattern as a mask.

[0135] Here, when an inorganic hard mask intermediate layer film is formed as the intermediate layer, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiON film) is formed by a CVD method, an ALD method, or the like. The nitride film formation method is not limited to the following, but for example, the methods described in Japanese Patent Laid-Open No. 2002-334869 and WO 2004 / 066377 can be used. A photoresist film can be formed directly on such a resist intermediate layer film, or an organic antireflective coating (BARC) can be formed on the resist intermediate layer film by spin coating, and then a photoresist film can be formed on top of that.

[0136] A polysilsesquioxane-based intermediate layer is also preferably used as the intermediate layer. By providing the resist intermediate layer with an anti-reflection coating effect, reflection tends to be effectively suppressed. Specific materials for the polysilsesquioxane-based intermediate layer are not limited to the following, but may be, for example, those described in JP-A-2007-226170 and JP-A-2007-226204.

[0137] The next etching of the substrate can also be carried out by a conventional method. For example, if the substrate is SiO ２ For SiN, etching can be performed using primarily fluorocarbon-based gases, while for p-Si, Al, and W, etching can be performed using primarily chlorine- or bromine-based gases. When etching a substrate with fluorocarbon-based gases, the silicon-containing resist of a two-layer resist process and the silicon-containing intermediate layer of a three-layer process are stripped simultaneously with substrate processing. On the other hand, when etching a substrate with chlorine- or bromine-based gases, the silicon-containing resist layer or silicon-containing intermediate layer is stripped separately, and generally, dry etching stripping using fluorocarbon-based gases is performed after substrate processing.

[0138] The resist underlayer film according to this embodiment is characterized by its excellent etching resistance against these substrates. The substrate can be selected from known materials as appropriate, and is not particularly limited, including Si, α-Si, p-Si, SiO ２ , SiN, SiON, W, TiN, Al, etc. The substrate may also be a laminate having a film to be processed (substrate to be processed) on a base material (support). Examples of such a film to be processed include Si, SiO２ Examples of low-k films include various low-k films and stopper films thereof, such as SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, and Al-Si, and these films are usually made of a material different from that of the substrate (support). The thickness of the substrate or film to be processed is not particularly limited, but is usually preferably about 50 to 1,000,000 nm, and more preferably 75 to 500,000 nm.

[0139] The resist auxiliary film composition of one embodiment of the present invention can also be used to form a resist intermediate layer film. A pattern formation method of another embodiment of the present invention includes the steps of: (B-1) forming a resist underlayer film on a substrate; (B-2) forming a resist intermediate layer film on the resist underlayer film using the resist auxiliary film composition of the embodiment of the present invention; (B-3) forming at least one photoresist layer on the resist intermediate layer film; (B-4) irradiating a predetermined region of the photoresist layer with radiation and developing the photoresist layer to form a resist pattern; and (B-5) etching the resist intermediate layer film using the resist pattern as a mask, etching the resist underlayer film using the obtained resist intermediate layer film pattern as an etching mask, and etching the substrate using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate.

[0140] 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.

[0141] (1) Film Thickness of Coating Film The film thickness of the coating film formed from the resist auxiliary film 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.).

[0142] (2) Content of structural units of resin The content of structural units of 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.

[0143] (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.

[0144] 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

[0145] [Resist auxiliary film composition containing novolac 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 mass ratio of 1:1 was used as the liquid crystal resin. 84 parts by mass of the cresol novolac resin and 16 parts by mass of a diazonaphthoquinone-type photosensitizer (product name "DTEP-350", manufactured by Daito ChemiX Co., Ltd.) were mixed and dissolved in a solvent of the type and blending ratio shown in Table 1 to prepare resist auxiliary film compositions having the concentrations of active ingredients (the cresol novolac resin and photosensitizer) shown in Tables 1 and 2. The prepared resist auxiliary film composition was then spin-coated on a silicon wafer at 1600 rpm to form a coating film, which was then pre-baked at 110°C for 90 seconds to form a resist auxiliary film. The film thickness was measured at five arbitrarily selected points on the resist auxiliary film, and the average value of the film thicknesses at the five points was calculated as the average film thickness. The results are shown in Tables 1 and 2.

[0146]

[0147]

[0148] Table 1 shows that the resist auxiliary film compositions prepared in Examples 1a to 14a can form thicker resist auxiliary films than the resist auxiliary film compositions of Comparative Examples 1b to 6b, which have similar resin concentrations. Table 2 also shows that the resist auxiliary film compositions prepared in Examples 15a to 47a can form thicker resist auxiliary films, despite having a low novolac resin content of 20 to 25% by mass.

[0149] [Resist auxiliary film composition containing ethylenically unsaturated resin (0)] 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 ethylenically unsaturated resin (0). The copolymer was mixed with a mixed solvent of the type and blending ratio shown in Tables 3 and 4 to prepare resist auxiliary film compositions having the active ingredient (ethylenically unsaturated resin (0)) concentration shown in Tables 3 and 4. The prepared resist auxiliary film composition was then spin-coated at 1600 rpm onto a silicon wafer to form a coating film, which was then pre-baked at 110°C for 90 seconds to form a resist auxiliary film. The film thickness was measured at five randomly selected locations on the resist auxiliary film, and the average film thickness of the five locations was calculated as the average film thickness. The results are shown in Tables 3 and 4.

[0150]

[0151]

[0152] From Tables 3 and 4, it can be seen that the resist auxiliary film compositions prepared in Examples 1b to 35b can form thicker auxiliary film resist films than the resist auxiliary film compositions of Comparative Examples 1b to 19b having the same resin content concentration.

[0153] [Resist auxiliary film compositions containing ethylenically unsaturated resins (i) to (vi)] Synthesis Examples 1 to 6 (Synthesis of ethylenically unsaturated resins (i) to (vi)) (1) Raw material monomers The following raw material monomers were used in synthesizing the ethylenically unsaturated 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

[0154]

[0155] (2) Synthesis of Ethylenically Unsaturated 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 ethylenically unsaturated resins (i) to (vi), respectively. For the resulting ethylenically unsaturated 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.

[0156]

[0157] Examples 1c to 18c, Comparative Examples 1c to 12c Any of the ethylenically unsaturated 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 auxiliary film compositions having the active ingredient (ethylenically unsaturated resins (i) to (vi)) concentrations shown in Tables 7 and 8. The prepared resist auxiliary film composition was then spin-coated at 3000 rpm onto a silicon wafer to form a coating, which was then pre-baked at 90°C for 60 seconds to form a resist auxiliary film. The film thickness was measured at five arbitrarily selected locations on the resist auxiliary film, 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.

[0158]

[0159]

[0160] Tables 7 and 8 show that the resist auxiliary film compositions prepared in Examples 1c to 18c can form thicker resist auxiliary films than the resist auxiliary film compositions of Comparative Examples 1c to 12c having the same resin concentration.

[0161] [Example 1d, Comparative Example 1d] (Preparation of Underlayer Film Composition) Underlayer film compositions were prepared to have the compositions shown in Table 9. The following polymers, acid generators, crosslinkers, and organic solvents were used. Polymer: A resin of formula (R1-1) was prepared as follows. That is, 30 g of 4,4-biphenol, 15 g of 4-biphenylaldehyde, and 100 mL of butyl acetate were charged, and 3.9 g of p-toluenesulfonic acid was added to prepare a reaction solution. This reaction solution was stirred at 90°C for 3 hours to carry out the reaction. Next, the reaction solution was concentrated, and the reaction solution was added dropwise to 400 mL of n-heptane. The resulting resin was coagulated and purified, and the resulting white powder was filtered and dried overnight under reduced pressure at 40°C to obtain a resin represented by the following formula (R1-1).

[0162] (R1-1) Acid generator: di-tertiary butyldiphenyliodonium nonafluoromethanesulfonate (DTDPI) manufactured by Midori Chemical Co., Ltd. Crosslinking agent: Nikalac MX270 (Nicalac) manufactured by Sanwa Chemical Co., Ltd. TMOM-BP (compound represented by the following formula) manufactured by Honshu Chemical Industry Co., Ltd. Organic solvent: methyl 2-hydroxyisobutyrate (HBM)

[0163]

[0164] Next, the underlayer film composition prepared in Example 1d was applied to a 300 nm thick SiO ２ An underlayer film with a thickness of 85 nm was formed by coating the underlayer film on a substrate and baking it at 240° C. for 60 seconds and then at 400° C. for 120 seconds. An ArF resist solution was coated on the underlayer film and baked at 130° C. for 60 seconds to form a photoresist layer with a thickness of 140 nm.

[0165] The ArF resist solution used was prepared by blending 5 parts by mass of a resin represented by the following formula (1d), 1 part by mass of triphenylsulfonium nonafluoromethanesulfonate, 2 parts by mass of tributylamine, and 92 parts by mass of PGMEA.

[0166] The resin of the following formula (1d) was prepared as follows. That is, 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g of methacryloyloxy-γ-butyrolactone, 2.08 g of 3-hydroxy-1-adamantyl methacrylate, and 0.38 g of azobisisobutyronitrile were dissolved in 80 mL of tetrahydrofuran to form a reaction solution. This reaction solution was polymerized for 22 hours under a nitrogen atmosphere at a reaction temperature of 63°C, and then the reaction solution was added dropwise to 400 mL of n-hexane. The resin thus produced was coagulated and purified, and the resulting white powder was filtered and dried overnight at 40°C under reduced pressure to obtain a resin represented by the following formula (1d).

[0167] (In formula (1d), 40, 40, and 20 indicate the ratio of each structural unit, and do not indicate a block copolymer.)

[0168] Next, the photoresist layer was exposed to light using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked at 115°C for 90 seconds (PEB), and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds, thereby obtaining a positive resist pattern.

[0169] Comparative Example 1d A photoresist layer was formed using SiO 2 in the same manner as in Example 1d, except that the resist underlayer film was not formed. ２ A positive resist pattern was obtained by forming it directly on the substrate.

[0170] [Evaluation] For each of Example 1d and Comparative Example 1d, the shapes of the resulting 40 nm L / S (1:1) and 80 nm L / S (1:1) resist patterns were observed using an electron microscope "S-4800" manufactured by Hitachi, Ltd. Regarding the shape of the resist pattern after development, those that showed no pattern collapse and good rectangularity were rated as "good," and those that did not were rated as "bad." Furthermore, as a result of this observation, the smallest line width that showed no pattern collapse and good rectangularity was used as an index of evaluation as resolution. Furthermore, the smallest amount of electron beam energy that could draw a good pattern shape was used as an index of evaluation as sensitivity. The results are shown in Table 10.

[0171]

[0172] As is clear from Table 10, the resist pattern in Example 1d was confirmed to be significantly superior in both resolution and sensitivity compared to Comparative Example 1d. It is believed that this result is due to the effect of the resist auxiliary film composition improving the adhesion of the resist pattern. Furthermore, it was confirmed that the resist pattern shape after development in Example 1d was free of pattern collapse and had good rectangularity. Furthermore, the difference in the resist pattern shape after development indicated that the resist auxiliary film composition in Example 1d had good adhesion to the resist material.

[0173] In this way, when the resist auxiliary film composition satisfying the requirements of this embodiment is used, a better resist pattern shape can be obtained compared to Comparative Example 1d, which does not satisfy these requirements. As long as the requirements of this embodiment are satisfied, resist auxiliary film compositions other than those described in the examples also exhibit the same effects.

[0174] [Example 2d] The resist auxiliary film composition prepared in Example 1d was applied to a 300 nm thick SiO ２The solution was applied to a substrate and baked at 240°C for 60 seconds and then at 400°C for 120 seconds to form a 90 nm thick resist underlayer film. A silicon-containing intermediate layer material was applied to the resist underlayer film and baked at 200°C for 60 seconds to form a 35 nm thick resist intermediate layer film. The ArF resist solution was then applied to the resist intermediate layer film and baked at 130°C for 60 seconds to form a 150 nm thick photoresist layer. The silicon-containing intermediate layer material used was the silicon-containing polymer (Polymer 1) described in Synthesis Example 1 of JP-A-2007-226170.

[0175] Next, the photoresist layer was exposed to light through a mask using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked at 115°C for 90 seconds (PEB), and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds, thereby obtaining a 45 nm L / S (1:1) positive resist pattern.

[0176] Thereafter, the silicon-containing resist intermediate layer film was dry-etched using the obtained resist pattern as a mask using "RIE-10NR" manufactured by Samco International Inc. Subsequently, the resist underlayer film was dry-etched using the obtained silicon-containing resist intermediate layer film pattern as a mask, and SiO ２ The film was then dry-etched.

[0177] The etching conditions for each method are as follows: Etching conditions for the resist pattern on the resist intermediate layer film: Output: 50 W, Pressure: 20 Pa, Time: 1 min, Etching gas: Ar gas flow rate: CF ４ Gas flow rate: 0 ２ Gas flow rate = 50:8:2 (sccm) Etching conditions for the resist middle layer film pattern onto the resist underlayer film Output: 50 W Pressure: 20 Pa Time: 2 min Etching gas Ar gas flow rate: CF ４ Gas flow rate: 0 ２Gas flow rate = 50:5:5 (sccm) SiO of resist underlayer film pattern ２ Etching conditions for the film: Output: 50 W, Pressure: 20 Pa, Time: 2 min, Etching gas: Ar gas flow rate: C ５ F １２ Gas flow rate: C ２ F ６ Gas flow rate: 0 ２ Gas flow rate = 50:4:3:1 (sccm)

[0178] <Evaluation of Pattern Shape> The cross section of the pattern of Example 2d obtained as described above (SiO ２ When the resist auxiliary film composition of the present embodiment was used to observe the shape of the SiO film after etching in the multilayer resist processing, the resist auxiliary film composition of the present embodiment was used to observe the shape of the SiO film after etching in the multilayer resist processing. ２ The film was confirmed to be rectangular in shape and to be in good condition with no defects.

[0179] [Resist auxiliary film composition containing ethylenically unsaturated resin (0) and acid generator] Resist auxiliary film compositions were prepared according to the formulations shown in Tables 11 and 12, and the solubility of the resins (i) to (v) and acid generators (i) to (iv) used as raw materials shown in Tables 11 and 12 was evaluated. <Solvents> HBM: methyl 2-hydroxyisobutyrate (manufactured by Mitsubishi Gas Chemical Company, Inc.) αMBM: methyl α-methoxyisobutyrate (synthesized with reference to US 2014 / 0275016) αFBM: methyl α-formyloxyisobutyrate (synthesized with reference to WO 2020 / 004467) αABM: methyl α-acetyloxyisobutyrate (synthesized with reference to WO 2020 / 004466) 3HBM: methyl 3-hydroxyisobutyrate (manufactured by Tokyo Chemical Industry Co., Ltd.) iPHIB: isopropyl 2-hydroxyisobutyrate (manufactured by Mitsubishi Gas Chemical Company, Inc.) 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)

[0180] Resins of the types shown in Table 11 were added to solvents of the types shown in Table 11 so that the resin concentration was 15 wt %, and acid generators of the types shown in Table 11 were added so that the acid generator concentration was 1 wt %, to prepare resist auxiliary film 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)

[0181] The resins shown in Table 12 were added to the solvents shown in Table 12 so that the resin concentration was 40 wt %, and the acid generators shown in Table 12 were added so that the acid generator concentrations were the predetermined concentrations, thereby preparing the resist auxiliary film 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 11 and 12.

[0182] As can be seen from Table 11, the resist auxiliary film compositions prepared in Examples A1-1 to A1-5 have superior resin solubility compared to the resist auxiliary film composition of Comparative Example A1-1, and various resist auxiliary film compositions can be prepared. In particular, the resist auxiliary film composition in which the solvent (B) contains αFBM as the solvent (B2) exhibits high solubility in any resin and is therefore preferably used.

[0183] Table 12 shows that the resist auxiliary film compositions prepared in Examples A2-1a to A2-5d have superior solubility for acid generators compared to the resist auxiliary film composition of Comparative Example A2-1, and that any acid generator can be used to prepare a resist auxiliary film composition. In particular, a resist auxiliary film composition in which the solvent (B) contains αMBM, αFBM, 3HBM, or PGME as the solvent (B2) exhibits high solubility for any acid generator and is therefore preferably used.

[0184] [Resist auxiliary film composition containing ethylenically unsaturated resin (0)] 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) as the ethylenically unsaturated resin (0) was mixed with the type of solvent shown in Table 13 to prepare resist auxiliary film compositions with the active ingredient (KrF resin) concentration shown in Table 13. The prepared resist auxiliary film composition was then spin-coated at 1500 rpm onto a silicon wafer to form a coating film, and the coating film was pre-baked at 140 °C for 60 seconds to form a resist auxiliary film. The film thickness was measured at five arbitrarily selected locations on the resist auxiliary film, and the average value of the film thicknesses at the five locations was calculated as the average film thickness to evaluate the film thickness. In addition, 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 13. 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

[0185]

[0186] Table 13 shows that the resist auxiliary film compositions prepared in Examples A3-1a to A3-5c can form thicker resist auxiliary films than the resist auxiliary film compositions of Comparative Examples A3-1a to A3-1b. In particular, resist auxiliary film 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 auxiliary film 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 auxiliary film compositions containing αMBM are suitable for use, as they can achieve a film thickness of 20 μm or more when the resin concentration is 45 wt%.

[0187] <Evaluation of In-Plane Uniformity of Resist Supplementary Film Composition> 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 14 to prepare resist supplementary film compositions with the active ingredient (KrF resin) concentration shown in Table 14. Using the prepared resist supplementary film composition, a coating film was formed on a silicon wafer with a main spin of 1200 rpm, and the coating film was prebaked at 110°C for 90 seconds to form a resist supplementary 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 on the resist supplementary 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 14. 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

[0188] [Resist Pattern Evaluation] (Preparation of Resist Supplementary Film Composition) A resist supplementary film composition was prepared to have the composition shown in Table 15. The following polymers, acid generators, crosslinkers, and organic solvents were used. Polymer: A resin of formula (R1-1) was prepared as follows. That is, 30 g of 4,4-biphenol, 15 g of 4-biphenylaldehyde, and 100 mL of butyl acetate were charged, and 3.9 g of p-toluenesulfonic acid was added to prepare a reaction solution. This reaction solution was stirred at 90°C for 3 hours to carry out a reaction. Next, the reaction solution was concentrated, and the reaction solution was added dropwise to 400 mL of n-heptane. The resin thus produced was coagulated and purified, and the resulting white powder was filtered and dried overnight at 40°C under reduced pressure to obtain a resin represented by the following formula (R1-1).

[0189] (R1-1) Acid generator: di-tertiary butyldiphenyliodonium nonafluoromethanesulfonate (DTDPI) manufactured by Midori Chemical Co., Ltd. Crosslinking agent: Nikalac MX270 (Nicalac) manufactured by Sanwa Chemical Co., Ltd. TMOM-BP (compound represented by the following formula) manufactured by Honshu Chemical Industry Co., Ltd. Organic solvents: methyl 2-hydroxyisobutyrate (HBM), methyl α-methoxyisobutyrate (αMBM), methyl α-formyloxyisobutyrate (αFBM), methyl 3-hydroxyisobutyrate (3HBM), isopropyl 2-hydroxyisobutyrate (iPHIB), 1-methoxy-2-propanol (PGME)

[0190]

[0191] Next, the resist auxiliary film compositions prepared in Examples A5-1 to A5-16 were applied to a 300 nm thick SiO ２ A resist underlayer film with a thickness of 85 nm was formed by coating the substrate with the solution and baking it at 240° C. for 60 seconds and then at 400° C. for 120 seconds. An ArF resist solution was coated on the resist underlayer film and baked at 130° C. for 60 seconds to form a photoresist layer with a thickness of 140 nm.

[0192] The ArF resist solution used was prepared by blending 5 parts by mass of a resin represented by the following formula (1d), 1 part by mass of triphenylsulfonium nonafluoromethanesulfonate, 2 parts by mass of tributylamine, and 92 parts by mass of PGMEA.

[0193] The resin of the following formula (1d) was prepared as follows. That is, 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g of methacryloyloxy-γ-butyrolactone, 2.08 g of 3-hydroxy-1-adamantyl methacrylate, and 0.38 g of azobisisobutyronitrile were dissolved in 80 mL of tetrahydrofuran to form a reaction solution. This reaction solution was polymerized for 22 hours under a nitrogen atmosphere at a reaction temperature of 63°C, and then the reaction solution was added dropwise to 400 mL of n-hexane. The resin thus produced was coagulated and purified, and the resulting white powder was filtered and dried overnight at 40°C under reduced pressure to obtain a resin represented by the following formula (1d).

[0194] (In formula (1d), 40, 40, and 20 indicate the ratio of each structural unit, and do not indicate a block copolymer.)

[0195] Next, the photoresist layer was exposed to light using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked at 115°C for 90 seconds (PEB), and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds, thereby obtaining a positive resist pattern.

[0196] Comparative Example A4 A photoresist layer was formed in the same manner as in Example A5-1, except that the resist underlayer film was not formed. ２ A positive resist pattern was obtained by forming it directly on the substrate.

[0197] [Evaluation] For each of Examples A5-1 to A5-16 and Comparative Example A5, the shapes of the resulting 40 nm L / S (1:1) and 80 nm L / S (1:1) resist patterns were observed using an electron microscope "S-4800" manufactured by Hitachi, Ltd. Regarding the shape of the resist pattern after development, those that showed no pattern collapse and good rectangularity were rated as "good," and those that did not were rated as "bad." Furthermore, as a result of this observation, the smallest line width that showed no pattern collapse and good rectangularity was used as an index of evaluation as resolution. Furthermore, the smallest amount of electron beam energy that could draw a good pattern shape was used as an index of evaluation as sensitivity. The results are shown in Table 16.

[0198]

[0199] As is clear from Table 16, the resist patterns in Examples A5-1 to A5-16 were confirmed to be significantly superior in both resolution and sensitivity compared to Comparative Example A5. It is believed that these results are due to the effect of the resist auxiliary film composition improving the adhesion of the resist pattern. Furthermore, it was confirmed that the resist pattern shapes of Examples A5-1 to A5-16 after development were free of pattern collapse and had good rectangularity. Furthermore, the differences in the resist pattern shapes after development indicated that the resist auxiliary film compositions of Examples A5-1 to A5-16 had good adhesion to the resist material.

[0200] In this way, when the resist auxiliary film composition satisfying the requirements of this embodiment is used, a better resist pattern shape can be obtained than in Comparative Example A5, which does not satisfy these requirements. As long as the requirements of this embodiment are satisfied, similar effects can be obtained with resist auxiliary film compositions other than those described in the examples.

[0201] [Examples A6-1 to A6-16] The resist auxiliary film compositions prepared in Examples A5-1 to A5-16 were applied to a 300 nm thick SiO ２ The solution was applied to a substrate and baked at 240°C for 60 seconds and then at 400°C for 120 seconds to form a 90 nm thick resist underlayer film. A silicon-containing intermediate layer material was applied to the resist underlayer film and baked at 200°C for 60 seconds to form a 35 nm thick resist intermediate layer film. The ArF resist solution was then applied to the resist intermediate layer film and baked at 130°C for 60 seconds to form a 150 nm thick photoresist layer. The silicon-containing intermediate layer material used was the silicon-containing polymer (Polymer 1) described in Synthesis Example 1 of JP-A-2007-226170.

[0202] Next, the photoresist layer was exposed to light through a mask using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked at 115°C for 90 seconds (PEB), and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds, thereby obtaining a 45 nm L / S (1:1) positive resist pattern.

[0203] Thereafter, the silicon-containing resist intermediate layer film was dry-etched using the obtained resist pattern as a mask using "RIE-10NR" manufactured by Samco International Inc. Subsequently, the resist underlayer film was dry-etched using the obtained silicon-containing resist intermediate layer film pattern as a mask, and SiO ２ The film was then dry-etched.

[0204] The etching conditions for each method are as follows: Etching conditions for the resist pattern on the resist intermediate layer film: Output: 50 W, Pressure: 20 Pa, Time: 1 min, Etching gas: Ar gas flow rate: CF ４ Gas flow rate: 0 ２ Gas flow rate = 50:8:2 (sccm) Etching conditions for the resist middle layer film pattern onto the resist underlayer film Output: 50 W Pressure: 20 Pa Time: 2 min Etching gas Ar gas flow rate: CF ４ Gas flow rate: 0 ２ Gas flow rate = 50:5:5 (sccm) SiO of resist underlayer film pattern ２ Etching conditions for the film: Output: 50 W, Pressure: 20 Pa, Time: 2 min, Etching gas: Ar gas flow rate: C ５ F １２ Gas flow rate: C ２ F ６ Gas flow rate: 0 ２ Gas flow rate = 50:4:3:1 (sccm)

[0205] <Evaluation of Pattern Shape> The pattern cross sections (SiO after etching) of Examples A6-1 to A6-11 and A6-14 to A6-16 obtained as described above were ２ When the resist auxiliary film composition of the present embodiment was used to observe the shape of the SiO film after etching in the multilayer resist processing, the resist auxiliary film composition of the present embodiment was used to observe the shape of the SiO film after etching in the multilayer resist processing. ２ The film was confirmed to be rectangular in shape and to be in good condition with no defects.

[0206] [Evaluation of embedding ability in uneven substrates] The embedding ability in uneven substrates was evaluated by the following procedure. The resist auxiliary coating compositions prepared in Examples A5-1 to A5-6 and A5-14 and the resist auxiliary coating composition A7 described below were applied to a 150 nm thick SiO ２The resist underlayer film was coated on a substrate and baked at 400°C for 60 seconds to form a resist underlayer film with a thickness of 100 nm. A cross section of the resist underlayer film obtained was cut out and observed under an electron microscope to evaluate its embeddability into a stepped substrate. The results are shown in Table 16. <Evaluation Criteria> A: 60 nm line and space SiO ２ There are no defects in the uneven parts of the substrate, and the resist underlayer film is embedded. C: 60 nm line and space SiO ２ There are defects in the uneven parts of the substrate, and the resist underlayer film is not embedded therein.

[0207] [Evaluation of Flatness] A SiO2 substrate was prepared by mixing trenches (aspect ratio: 1.5) with a width of 100 nm, a pitch of 150 nm, and a depth of 150 nm and trenches (open spaces) with a width of 5 μm and a depth of 150 nm. ２ The resist auxiliary film compositions obtained above were each applied onto a stepped substrate. Then, the coating was baked at 400°C for 120 seconds in an air atmosphere to form a resist underlayer film with a film thickness of 100 nm. The shape of the resist underlayer film was observed with a scanning electron microscope (Hitachi High-Technologies Corporation's "S-4800"), and the difference (ΔFT) between the maximum and minimum film thicknesses of the resist underlayer film on the trench or space was measured. The results are shown in Table 17. <Evaluation Criteria> S: ΔFT<10 nm (best flatness) A: 10 nm≦ΔFT<20 nm (good flatness) B: 20 ​​nm≦ΔFT<40 nm (fairly good flatness) C: 40 nm≦ΔFT (poor flatness)

[0208]

[0209] (Preparation of Resist Auxiliary Coating Composition A7) Resist auxiliary coating composition A7 was prepared in the same manner as in Example A5-4, except that the solvent was changed from HBM to 1-methoxy-2-propanol (PGME).

[0210] <Evaluation of Step-Filling Ability and Flatness> It was confirmed that the step-filling ability and flatness of Examples A7-1 to A7-7 obtained as described above were good. In particular, the resist auxiliary film composition containing 3HBM as the solvent (B2) or the resist auxiliary film composition containing iPHIB as the solvent (B1) is preferably used because of its excellent step-filling ability and flatness.

[0211] As long as the requirements of this embodiment are met, the same effects can be achieved with resist auxiliary film compositions other than those described in the examples.

Claims

1. A resist auxiliary film 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 auxiliary film 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 auxiliary film 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 auxiliary film 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 auxiliary film composition according to claim 1.

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

6. The resist auxiliary film 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-acetoxyisobutyrate, methyl 3-hydroxyisobutyrate, and 1-methoxy-2-propanol.

7. The resist auxiliary film 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-acetoxyisobutyrate, and methyl 3-hydroxyisobutyrate.

8. The resist auxiliary film 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 auxiliary film 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).

10. The resist auxiliary film 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 auxiliary film composition.

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

12. The resist auxiliary film composition according to claim 1, wherein the resin (A) contains an ethylenically unsaturated resin (A2).

13. The resist auxiliary film composition according to claim 1, wherein the resin (A) contains a high-carbon resin (A3).

14. The resist auxiliary film composition according to claim 1, wherein the resin (A) contains a silicon-containing resin (A4).

15. The resist auxiliary film composition according to any one of claims 1 to 14, wherein the resist auxiliary film is a resist underlayer film.

16. The resist auxiliary film composition according to any one of claims 1 to 14, wherein the resist auxiliary film is a resist intermediate layer film.

17. A step (A-1) of forming a resist underlayer film on a substrate using the resist auxiliary film composition according to claim 15, A step (A-2) of forming at least one photoresist layer on the resist underlayer film; After the step (A-2), a step (A-3) of irradiating a predetermined region of the photoresist layer with radiation and performing development; A method for forming a pattern including the above.

18. A step (B-1) of forming a resist underlayer film on a substrate using the resist auxiliary film composition according to claim 15; A step (B-2) of forming a resist intermediate layer film on the resist underlayer film; A step (B-3) of forming at least one photoresist layer on the resist intermediate layer film; After the step (B-3), a step (B-4) of irradiating a predetermined region of the photoresist layer with radiation, developing, and forming a resist pattern; After the step (B-4), etching the resist intermediate layer film using the resist pattern as a mask, etching the resist underlayer film using the obtained resist intermediate layer film pattern as an etching mask, and etching the substrate using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate (B-5); A method for forming a pattern including the above.

19. A step (B-1) of forming a resist underlayer film on a substrate; A step (B-2) of forming a resist intermediate layer film on the resist underlayer film using the resist auxiliary film composition according to claim 16; A step (B-3) of forming at least one photoresist layer on the resist intermediate layer film; After the step (B-3), a step (B-4) of irradiating a predetermined region of the photoresist layer with radiation, developing, and forming a resist pattern; After the step (B-4), the resist intermediate layer film is etched using the resist pattern as a mask, the obtained resist intermediate layer film pattern is used as an etching mask to etch the resist lower layer film, and the obtained resist lower layer film pattern is used as an etching mask to etch the substrate to form a pattern on the substrate (step (B-5)); A method for forming a pattern including

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