WO2019131434A1

WO2019131434A1 - Resist pattern forming method

Info

Publication number: WO2019131434A1
Application number: PCT/JP2018/046982
Authority: WO
Inventors: 雄哲白木; 紳一河野; 慶晃大野; 智成砂道; 彩齊藤
Original assignee: 東京応化工業株式会社
Priority date: 2017-12-28
Filing date: 2018-12-20
Publication date: 2019-07-04
Also published as: CN111566562B; CN111566562A; SG11202005914XA; KR102438832B1; JP2019120765A; JP7076207B2; KR20200088459A

Abstract

A resist pattern forming method which comprises: a step wherein a resist film having a film thickness of 7 μm or more is formed on a supporting body with use of a resist composition; a step wherein the resist film is exposed to light; and a step wherein the resist film after light exposure is developed, thereby forming a resist pattern. With respect to this resist pattern forming method, the resist composition contains a resin component that has a constituent unit represented by general formula (a10-1), a constituent unit containing an acid-uncleavable alicyclic group and a constituent unit containing an acid-decomposable group, the polarity of which is increased by the action of an acid. (In formula (a10-1), R represents a hydrogen atom, an alkyl group or a halogenated alkyl group; Yax1 represents a single bond or a divalent linking group; Wax1 represents an (nax1 + 1)-valent aromatic hydrocarbon group; and nax1 represents an integer of 1-3.)

Description

Resist pattern formation method

The present invention relates to a method of forming a resist pattern.
Priority is claimed on Japanese Patent Application No. 2017-254871, filed Dec. 28, 2017, the content of which is incorporated herein by reference.

In the lithography technology, for example, a resist film made of a resist material is formed on a substrate, selective exposure is performed on the resist film, and a development process is performed to form a resist pattern having a predetermined shape on the resist film. Process is performed. A resist material that changes to a characteristic that the exposed part of the resist film dissolves in the developer is called a positive type, and a resist material that changes to a characteristic that the exposed part of the resist film does not dissolve to the developer is called a negative type.
In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization of patterns has progressed with advances in lithography technology. Generally as a method of refinement | miniaturization, shortening of the wavelength (exposure) of the exposure light source is performed. Specifically, conventionally, ultraviolet rays represented by g-line and i-line have been used, but at present, mass production of semiconductor devices using KrF excimer laser or ArF excimer laser is performed. In addition, studies are being made on EUV (extreme ultraviolet), EB (electron beam), X-rays, etc., which have a shorter wavelength (high energy) than these excimer lasers.

The resist material is required to have such lithography characteristics as sensitivity to the exposure light source and resolution capable of reproducing a pattern of fine dimensions.
As a resist material satisfying such requirements, conventionally, a chemically amplified resist composition comprising a base component whose solubility in a developer changes by the action of an acid, and an acid generator component which generates an acid upon exposure to light Is used.
For example, when the developer is an alkali developer (alkali development process), as a positive-working chemically amplified resist composition, a resin component (base resin) whose acid solubility increases with the action of an acid and acid generation Those containing an agent component are generally used. When a resist film formed using such a resist composition is selectively exposed at the time of forming a resist pattern, an acid is generated from the acid generator component in the exposed portion, and the polarity of the base resin is increased by the action of the acid. As a result, the exposed portion of the resist film becomes soluble in the alkali developer. Therefore, by performing alkali development, a positive pattern in which the unexposed area of the resist film remains as a pattern is formed.
On the other hand, when such a chemically amplified resist composition is applied to a solvent development process using a developer containing an organic solvent (organic developer), the relative development of the organic resin occurs when the polarity of the base resin is increased. Since the solubility in the solution is reduced, the unexposed area of the resist film is dissolved and removed by the organic developer, and a negative resist pattern is formed in which the exposed area of the resist film remains as a pattern. Such a solvent development process for forming a negative resist pattern is sometimes called a negative development process.

So far, as a base resin of a chemically amplified resist composition, for example, polyhydroxystyrene (PHS) having high transparency to a KrF excimer laser (248 nm) or a resin having its hydroxyl group protected by an acid dissociable, dissolution inhibiting group (PHS-based resin) has been used. For example, a resin (a (meth) acrylic resin) in which a hydroxyl group at a carboxy group of (meth) acrylic acid is protected with an acid dissociable, dissolution inhibiting group has been used for ArF excimer laser (193 nm) (for example, Patent Document 1).
The acid dissociable, dissolution inhibiting group is typically represented by a so-called acetal group such as a chain ether group represented by 1-ethoxyethyl group or a cyclic ether group represented by tetrahydropyranyl group, tert-butyl group Tertiary alkyl groups, tertiary alkoxycarbonyl groups represented by tert-butoxycarbonyl group, etc. are mainly used.

Also, as the acid generator component to be used in the chemical amplification resist composition, a wide variety of ones have been proposed so far, for example, onium salt-based acid generators such as iodonium salts and sulfonium salts, oxime sulfonate-based There are known an acid generator, a diazomethane-based acid generator, a nitrobenzyl sulfonate-based acid generator, an iminosulfonate-based acid generator, a disulfone-based acid generator, and the like.
Among these, onium salt-based acid generators are widely used, and those having an onium ion such as triphenylsulfonium in the cation portion are mainly used. For the anion part of this onium salt-based acid generator, an alkyl sulfonate ion or a fluorinated alkyl sulfonate ion in which part or all of hydrogen atoms of the alkyl group are substituted with a fluorine atom is generally used. ing.

By the way, at present, with the high integration of LSI and the high speed of communication, the memory capacity is required to be increased, and the further miniaturization of the pattern is rapidly progressing. However, in lithography by electron beam or EUV, although the aim is to form a fine pattern of several tens of nm, there are many problems such as low productivity, and there are limits in the technique by microfabrication.
On the other hand, in addition to miniaturization, development of a three-dimensional structure device is being advanced in which memory capacity is increased by stacking cells stacked up.

Unexamined-Japanese-Patent No. 2003-241385

In the manufacture of the above three-dimensional structure device, a thick film resist film having a film thickness larger than that of the prior art, for example, a film thickness of 7 μm or more is formed on the surface of a workpiece to form a resist pattern. It has the process of performing an etching etc. When a chemically amplified resist composition is used here, it is more difficult to maintain the sensitivity at the time of exposure as the film thickness of the resist becomes thicker. When a thick film resist film is to be formed using a conventional chemically amplified resist composition, there is a problem that a large amount of exposure is required and the sensitivity is lowered. Further, there is also a problem that the resolution for development is lowered and it is difficult to obtain a desired resist pattern shape.

The present invention has been made in view of the above circumstances, and exhibits a high sensitivity even when forming a thick film resist film having a film thickness of 7 μm or more, and forms a pattern having a good shape. It is an object of the present invention to provide a method of forming a resist pattern that can be used.

In order to solve the above-mentioned subject, the present invention adopted the following composition.
That is, a method of forming a resist pattern according to an aspect of the present invention comprises: (i) forming a resist film having a thickness of 7 μm or more using a resist composition on a support; and exposing the resist film And (ii) developing the resist film after the exposure to form a resist pattern (iii), wherein the resist composition generates an acid upon exposure, and Solubility in a developing solution is changed by the action, and a structural unit (a4) represented by the following general formula (a10-1) and a structural unit (a4) containing a non-acid dissociable aliphatic cyclic group And a resin component (A1) having a structural unit (a1) containing an acid-degradable group whose polarity is increased by the action of an acid.

[Wherein, R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms]. Ya ^x1 is a single bond or a divalent linking group. Wa ^x1 is an (n _ax1 +1) _-valent aromatic hydrocarbon group. n _ax1 is an integer of 1 to 3. ]

According to the present invention, it is possible to provide a resist pattern forming method which exhibits high sensitivity and can form a pattern having a good shape even when forming a thick film resist film having a film thickness of 7 μm or more. it can.

In the present specification and claims, “aliphatic” is a concept relative to an aromatic and is defined to mean a group, a compound or the like having no aromaticity.
The term "alkyl group" is intended to include linear, branched and cyclic monovalent saturated hydrocarbon groups, unless otherwise specified. The same applies to the alkyl group in the alkoxy group.
The "alkylene group" is intended to include a linear, branched and cyclic divalent saturated hydrocarbon group unless otherwise specified.
The “halogenated alkyl group” is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
The "fluorinated alkyl group" or "fluorinated alkylene group" refers to a group in which part or all of the hydrogen atoms of the alkyl group or the alkylene group are substituted with a fluorine atom.
The "constituent unit" means a monomer unit (monomer unit) constituting a polymer compound (resin, polymer, copolymer).
When it is described that “it may have a substituent”, when replacing a hydrogen atom (—H) with a monovalent group and when replacing a methylene group (—CH ₂ —) with a divalent group And both.
"Exposure" is a concept that includes general radiation irradiation.

The “constituent unit derived from acrylic acid ester” means a constitutional unit formed by cleavage of the ethylenic double bond of acrylic acid ester.
The “acrylic acid ester” is a compound in which the hydrogen atom at the carboxy group terminal of acrylic acid (CH ₂ CHCH—COOH) is substituted with an organic group.
In the acrylic ester, the hydrogen atom bonded to the carbon atom at the α-position may be substituted by a substituent. The substituent (R ^α0 ) which substitutes a hydrogen atom bonded to a carbon atom at the α-position is an atom or a group other than a hydrogen atom, and is, for example, an alkyl group having 1 to 5 carbon atoms, a halogen atom having 1 to 5 carbon atoms An alkyl group etc. are mentioned. Further, itaconic acid diesters in which the substituent (R ^α0 ) is substituted with a substituent containing an ester bond, and α hydroxy acrylic esters in which the substituent (R ^α0 ) is substituted with a hydroxyalkyl group or a group modified with a hydroxyl group thereof Shall be included. In addition, the carbon atom of alpha-position of acrylic acid ester is a carbon atom which the carbonyl group of acrylic acid has couple | bonded, unless there is particular notice.
Hereinafter, an acrylic acid ester in which a hydrogen atom bonded to a carbon atom at the α position is substituted with a substituent may be referred to as an α-substituted acrylic acid ester. Moreover, an acrylic ester and an alpha substituted acrylic ester may be included and it may be called "(alpha substituted) acrylic ester." In addition, acrylic acid in which a hydrogen atom bonded to a carbon atom at the α position is substituted with a substituent is sometimes referred to as α-substituted acrylic acid. Moreover, acrylic acid and alpha substitution acrylic acid may be included and it may be called "(alpha substitution) acrylic acid."

The “constituent unit derived from acrylamide” means a constituent unit formed by cleavage of the ethylenic double bond of acrylamide.
In the acrylamide, the hydrogen atom bonded to the carbon atom at the α position may be substituted by a substituent, and one or both of the hydrogen atoms of the amino group of acrylamide may be substituted by a substituent. The carbon atom at the α-position of acrylamide is a carbon atom to which a carbonyl group of acrylamide is bonded unless otherwise specified.
As the substituent for substituting the hydrogen atom bonded to the carbon atom at the α-position of acrylamide, those similar to the ones mentioned as the substituent at the α-position (substituent (R ^α0 )) in the above-mentioned α-substituted acrylic acid ester It can be mentioned.

The “structural unit derived from hydroxystyrene” means a structural unit formed by cleavage of the ethylenic double bond of hydroxystyrene. The “constituent unit derived from hydroxystyrene derivative” means a constituent unit formed by cleavage of the ethylenic double bond of the hydroxystyrene derivative.
The term "hydroxystyrene derivative" is a concept including those in which a hydrogen atom at the alpha position of hydroxystyrene is substituted with another substituent such as an alkyl group or a halogenated alkyl group, and derivatives thereof. As their derivatives, those in which the hydrogen atom of hydroxystyrene which may be substituted with a hydrogen atom at the α position is substituted with an organic group; even if the hydrogen atom at the α position is substituted by a substituent A compound in which a substituent other than a hydroxyl group is bonded to the benzene ring of good hydroxystyrene, and the like can be mentioned. The alpha position (carbon atom at the alpha position) refers to the carbon atom to which the benzene ring is bonded unless otherwise specified.
As a substituent which substitutes the hydrogen atom of alpha position of hydroxystyrene, the thing similar to what was mentioned as a substituent of alpha position in the above-mentioned alpha substitution acrylic acid ester is mentioned.

The “constituent unit derived from vinylbenzoic acid or a vinylbenzoic acid derivative” means a constitutional unit formed by cleavage of an ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acid derivative.
The "vinyl benzoic acid derivative" is a concept including those in which the hydrogen atom at the α-position of vinyl benzoic acid is substituted with an alkyl group, another substituent such as a halogenated alkyl group, and derivatives thereof. As their derivatives, those in which the hydrogen atom at the α-position is substituted with an organic group and the hydrogen atom of the carboxy group of vinyl benzoic acid which may be substituted with a substituent; the hydrogen atom at the α-position is substituted with a substituent And the like in which a substituent other than a hydroxyl group and a carboxy group is bonded to the benzene ring of vinyl benzoic acid which may be mentioned. The alpha position (carbon atom at the alpha position) refers to the carbon atom to which the benzene ring is bonded unless otherwise specified.

The alkyl group as a substituent at the α-position is preferably a linear or branched alkyl group, and specifically, an alkyl group having 1 to 5 carbon atoms (a methyl group, an ethyl group, a propyl group, an isopropyl group) , N-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group) and the like.
In addition, specific examples of the halogenated alkyl group as a substituent at the α-position include groups in which part or all of the hydrogen atoms of the above “alkyl group as a substituent at the α-position” are substituted with a halogen atom Be Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is particularly preferable.
Further, specific examples of the hydroxyalkyl group as a substituent at the α-position include groups in which part or all of the hydrogen atoms of the above-mentioned “alkyl group as a substituent at the α-position” are substituted with a hydroxyl group. The number of hydroxyl groups in the hydroxyalkyl group is preferably 1 to 5, and most preferably 1.

In the present specification and the claims, some of the structures represented by the chemical formulas have asymmetric carbon, and there may be enantiomers and diastereomers, The case is representative of the isomers in one formula. These isomers may be used alone or as a mixture.

(Resist pattern formation method)
In the resist pattern forming method of the present embodiment, a step (i) of forming a resist film having a film thickness of 7 μm or more on a support using a resist composition, a step (ii) of exposing the resist film, and Developing the resist film of the above to form a resist pattern (iii). In the method for forming a resist pattern according to this aspect, a specific resist composition is selected in step (i).
The method for forming a resist pattern according to this aspect can be performed, for example, as follows.

Process (i):
First, a specific resist composition to be described later is coated on a support by a spinner or the like, and baked (post applied bake (PAB)) treatment, for example, at 80 to 150 ° C., preferably 100 to 150 ° C. (more preferably) It is applied for 40 to 120 seconds, preferably 60 to 120 seconds (more preferably 80 to 100 seconds) under a temperature condition of more than 100.degree. C. and 150.degree. C.) to form a resist film having a film thickness of 7 .mu.m or more.

Process (ii):
Next, the resist film is selectively exposed by, for example, exposure through a mask (mask pattern) on which a predetermined pattern is formed using, for example, an exposure apparatus or the like, and then baked (post exposure bake (PEB) 2.) The treatment is carried out, for example, at a temperature of 80 to 150 ° C., preferably 90 to 130 ° C., for 40 to 120 seconds, preferably 60 to 100 seconds.

Step (iii):
Next, the resist film after the exposure is developed. The development processing is performed using an alkaline developer in the case of an alkali development process and using a developer (organic developer) containing an organic solvent in the case of a solvent development process.
After the development process, a rinse process is preferably performed. In the case of the alkali development process, water rinse using pure water is preferable, and in the case of the solvent development process, it is preferable to use a rinse solution containing an organic solvent.
In the case of the solvent development process, after the development process or rinse process, a process of removing the developer or rinse solution adhering on the pattern with a supercritical fluid may be performed.

After development processing or rinse processing, drying is performed. Further, in some cases, a bake treatment (post bake) may be performed after the development treatment.
Thus, a resist pattern can be formed.

The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for an electronic component and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon wafer, a metal substrate such as copper, chromium, iron, aluminum or the like, a glass substrate, etc. may be mentioned. As a material of the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
In addition, as the support, an inorganic and / or organic film may be provided on the substrate as described above. Examples of inorganic films include inorganic antireflective films (inorganic BARCs). Examples of the organic film include an organic antireflective film (organic BARC) and an organic film such as a lower organic film in a multilayer resist method.
Here, in the multilayer resist method, at least one organic film (lower organic film) and at least one resist film (upper resist film) are provided on a substrate, and a resist pattern formed on the upper resist film is used as a mask. It is a method of patterning the lower organic film, and is said to be able to form a pattern with a high aspect ratio. That is, according to the multilayer resist method, since the required thickness can be secured by the lower layer organic film, the resist film can be thinned, and a fine pattern with a high aspect ratio can be formed.
In the multilayer resist method, basically, a method of forming a two-layer structure of an upper layer resist film and a lower layer organic film (bilayer resist method), and one or more intermediate layers between the upper layer resist film and the lower layer organic film It is divided into the method (three-layer resist method) of forming a multilayer structure of three or more layers provided with (metal thin film etc.).

The resist pattern forming method of the present embodiment is a method useful for forming a thick resist film, and the film thickness of the resist film formed in the step (i) is 7 μm or more.
The film thickness of the resist film formed in the step (i) is more preferably 8 μm or more, particularly preferably 10 μm or more, and the upper limit of the film thickness is substantially 30 μm or less.

The wavelength used for exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. It can be done using radiation.
The method for forming a resist pattern according to this aspect is a particularly suitable method when irradiating the resist film with KrF excimer laser light in the step (ii).

The exposure method of the resist film may be a normal exposure (dry exposure) performed in an inert gas such as air or nitrogen, or may be a liquid immersion exposure (Liquid Immersion Lithography).
In immersion exposure, the space between the resist film and the lowermost lens of the exposure apparatus is previously filled with a solvent (immersion medium) having a refractive index larger than that of air, and exposure (immersion exposure) is performed in that state It is an exposure method.
As the immersion medium, a solvent having a refractive index which is larger than the refractive index of air and smaller than the refractive index of the resist film to be exposed is preferable. The refractive index of the solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, a silicon-based solvent, a hydrocarbon-based solvent and the like.
Specific examples of the fluorine-based inert liquid include fluorine-based compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as main components. Examples thereof include liquids, and those having a boiling point of 70 to 180 ° C. are preferable, and those having a boiling point of 80 to 160 ° C. are more preferable. It is preferable that the fluorine-based inert liquid has a boiling point in the above range, since the medium used for immersion can be removed by a simple method after the completion of exposure.
As the fluorine-based inert liquid, particularly preferred is a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms. Specific examples of perfluoroalkyl compounds include perfluoroalkyl ether compounds and perfluoroalkylamine compounds.
Furthermore, specifically, as the perfluoroalkyl ether compound, perfluoro (2-butyl-tetrahydrofuran) (boiling point 102 ° C.) can be mentioned, and as the perfluoroalkylamine compound, perfluorotributylamine ( Boiling point 174 ° C.) can be mentioned.
Water is preferably used as the immersion medium from the viewpoints of cost, safety, environmental problems, versatility and the like.

Examples of the alkali developer used for development in the alkali development process include an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide (TMAH).
The organic solvent contained in the organic developer used for development in the solvent development process may be any solvent capable of dissolving the component (A) (the component (A) before exposure), and among known organic solvents It can be selected appropriately. Specifically, polar solvents such as ketone solvents, ester solvents, alcohol solvents, nitrile solvents, amide solvents, ether solvents, hydrocarbon solvents and the like can be mentioned.
The ketone solvent is an organic solvent containing C—C (= O) —C in the structure. The ester solvent is an organic solvent containing C—C (= O) —O—C in the structure. The alcohol solvent is an organic solvent containing an alcoholic hydroxyl group in its structure. The "alcoholic hydroxyl group" means a hydroxyl group bonded to a carbon atom of an aliphatic hydrocarbon group. The nitrile solvent is an organic solvent containing a nitrile group in the structure. An amide solvent is an organic solvent containing an amide group in the structure. An ether solvent is an organic solvent containing C—O—C in its structure.
Among organic solvents, an organic solvent containing a plurality of functional groups characterizing each of the above-mentioned solvents in the structure is also present, in which case it corresponds to any solvent type containing a functional group possessed by the organic solvent. It shall be. For example, diethylene glycol monomethyl ether corresponds to any of alcohol solvents and ether solvents in the above classification.
The hydrocarbon-based solvent is a hydrocarbon solvent composed of an optionally halogenated hydrocarbon and having no substituent other than a halogen atom. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, A fluorine atom is preferable.
Among the above organic solvents that the organic developer contains, polar solvents are preferable, and ketone solvents, ester solvents, nitrile solvents and the like are preferable.

Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone And methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methylnaphthyl ketone, isophorone, propylene carbonate, γ-butyrolactone, methyl amyl ketone (2-heptanone) and the like. Among these, as the ketone-based solvent, methyl amyl ketone (2-heptanone) is preferable.

As ester solvents, for example, methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, isoamyl acetate, methoxyethyl acetate, ethyl ethoxyacetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol Monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate , -Methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2-ethoxybutyl acetate , 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate , 3-Methyl 4-methoxypentyl acetate, 4-methyl 4-methoxypentyl acetate, propylene glycol diacetate, ant Methyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, acetoacetate Ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate , Ethyl 3-ethoxy propionate, propyl 3-methoxy propionate and the like. Among these, butyl ester is preferable as the ester solvent.

Examples of nitrile solvents include acetonitrile, propionitrile, valeronitrile, butyronitrile and the like.

Known additives can be blended into the organic developer as required. Examples of the additive include surfactants. The surfactant is not particularly limited, and, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used. The surfactant is preferably a nonionic surfactant, and more preferably a nonionic fluorinated surfactant or a nonionic silicone surfactant.
When the surfactant is blended, the blending amount is usually 0.001 to 5% by mass, preferably 0.005 to 2% by mass, and preferably 0.01 to 0. 5 mass% is more preferable.

The development processing can be carried out by a known development method, for example, a method of immersing the support in a developer for a fixed time (dip method), a developer is raised on the surface of the support by surface tension and rested for a fixed time Method (paddle method), method of spraying the developer on the surface of the support (spray method), coating the developer while scanning the developer coating nozzle at a constant speed on the support rotating at a constant speed The following method may be mentioned (dynamic dispensing method).

As the organic solvent contained in the rinse solution used for the rinse treatment after development processing in the solvent development process, for example, among the organic solvents listed as the organic solvent used for the organic developer, one that does not easily dissolve the resist pattern is appropriately selected Can be used. Usually, at least one solvent selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents and ether solvents is used. Among these, at least one selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents and amide solvents is preferable, and at least one selected from alcohol solvents and ester solvents is more preferable. Preferably, alcohol solvents are particularly preferred.
The alcohol solvent used for the rinse solution is preferably a monohydric alcohol having 6 to 8 carbon atoms, and the monohydric alcohol may be linear, branched or cyclic. Specifically, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol etc. Be Among these, 1-hexanol, 2-heptanol and 2-hexanol are preferable, and 1-hexanol and 2-hexanol are more preferable.
One of these organic solvents may be used alone, or two or more thereof may be used in combination. Moreover, you may mix and use with the organic solvent and water other than the above. However, in consideration of the development characteristics, the blending amount of water in the rinse solution is preferably 30% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and 3% by mass with respect to the total amount of rinse solution. The following are particularly preferred.
A well-known additive can be mix | blended with a rinse agent as needed. Examples of the additive include surfactants. As the surfactant, the same as described above may be mentioned, and a nonionic surfactant is preferable, and a nonionic fluorine-based surfactant or a nonionic silicon-based surfactant is more preferable.
When the surfactant is blended, the blending amount is usually 0.001 to 5% by mass, preferably 0.005 to 2% by mass, and 0.01 to 0.5% by mass with respect to the total amount of the rinse solution. % Is more preferable.

The rinse process (washing process) using the rinse liquid can be implemented by the well-known rinse method. As a method of the rinse treatment, for example, a method of continuously applying a rinse liquid on a support rotating at a constant speed (rotation coating method), a method of immersing a support in a rinse liquid for a fixed time (dip method) The method (spray method) etc. which spray a rinse agent on the support surface are mentioned.

<Resist composition>
In the resist pattern forming method of the present embodiment described above, a specific resist composition is used in step (i).
Such a specific resist composition generates an acid upon exposure to light, and the action of the acid changes the solubility in a developer. Examples of this resist composition include an embodiment containing a base component (A) (hereinafter also referred to as "component (A)") whose solubility in a developer changes due to the action of an acid.

The resist composition of the present embodiment is suitable for forming a resist pattern that is exposed to KrF excimer laser light.
Further, the resist composition of the present embodiment is useful as a resist agent for forming a thick resist film on a support, and is suitable for forming a resist film having a film thickness of 7 μm or more. is there.

When a resist film is formed using the resist composition of the present embodiment and selective exposure is performed on the resist film, an acid is generated in the exposed portion of the resist film, and the action of the acid causes the component (A) to be generated. The solubility of the resist film in the unexposed area of the resist film changes while the solubility of the component (A) in the developer solution does not change in the unexposed area of the resist film. There is a difference in solubility in the solution. Therefore, when the resist film is developed, if the resist composition is positive, the exposed portion of the resist film is dissolved and removed to form a positive resist pattern, and if the resist composition is negative, the resist film is not formed. The exposed portion is dissolved and removed to form a negative resist pattern.

In this specification, a resist composition in which a resist film exposed portion is dissolved and removed to form a positive resist pattern is referred to as a positive resist composition, and a resist film unexposed portion is dissolved and removed to form a negative resist pattern. The resist composition to be formed is referred to as a negative resist composition.
The resist composition of the present embodiment may be a positive resist composition or a negative resist composition.
In addition, the resist composition of the present embodiment may be for an alkaline development process using an alkaline developer for development at the time of forming a resist pattern, and a developer containing an organic solvent in the development (organic developer) It may be for a solvent development process using
That is, the resist composition of the present embodiment is a "positive resist composition for an alkali development process" which forms a positive resist pattern in an alkali development process, and a "solvent development" which forms a negative resist pattern in a solvent development process. It is a negative resist composition for process.

The resist composition of the present embodiment has an acid generating ability to generate an acid upon exposure, and the component (A) may generate an acid upon exposure, and it is added separately from the component (A). The agent components may generate an acid upon exposure.
Specifically, the resist composition of the embodiment may contain (1) an acid generator component (B) (hereinafter referred to as "component (B)") that generates an acid upon exposure to light; (2) The component (A) may be a component that generates an acid upon exposure; (3) the component (A) is a component that generates an acid upon exposure, and further contains the component (B) It may be
That is, in the case of the above (2) or (3), the component (A) becomes “a base component which generates an acid upon exposure and whose solubility in a developer changes by the action of the acid”. When the component (A) generates an acid upon exposure and the solubility in a developer changes by the action of the acid, the component (A1) described later generates an acid upon exposure, and It is preferable that it is a polymer compound whose solubility in a developer changes by the action of an acid. As such a high molecular compound, a copolymer having a structural unit capable of generating an acid upon exposure can be used.
As a structural unit which generate | occur | produces an acid by exposure, a well-known thing is mentioned, for example.
The resist composition of this embodiment is particularly preferably the case of the above (1).

«(A) component»
The component (A) is a base component whose solubility in a developer changes due to the action of an acid.
In the present embodiment, the “base component” is an organic compound having a film forming ability, and preferably an organic compound having a molecular weight of 500 or more is used. When the molecular weight of the organic compound is 500 or more, the film forming ability is improved, and in addition, it becomes easy to form a nano-level resist pattern.
Organic compounds used as a base component are roughly classified into non-polymers and polymers.
As the non-polymer, one having a molecular weight of 500 or more and less than 4,000 is usually used. The term "low molecular weight compound" hereinafter refers to a non-polymer having a molecular weight of 500 or more and less than 4,000.
As the polymer, one having a molecular weight of 1,000 or more is usually used. Hereinafter, the term "resin", "polymer compound" or "polymer" refers to a polymer having a molecular weight of 1000 or more.
As a molecular weight of a polymer, the weight average molecular weight of polystyrene conversion by GPC (gel permeation chromatography) shall be used.

The component (A) in the resist composition of this embodiment contains a resin component (A1) (hereinafter also referred to as “component (A1)”) whose solubility in a developer changes due to the action of an acid.
As the component (A), at least the component (A1) is used, and another polymer compound and / or low molecular weight compound may be used in combination with the component (A1).

The component (A1) in the present embodiment includes a structural unit (a10) represented by General Formula (a10-1) described later, a structural unit (a4) containing an acid non-dissociative aliphatic cyclic group, and an acid And a structural unit (a1) containing an acid-degradable group whose polarity is increased by the action of The component (A1) may have other structural units as necessary in addition to the structural unit (a10), the structural unit (a4) and the structural unit (a1).

In the resist composition of the present embodiment, since the structural unit (a1) contains an acid dissociable group, by using the component (A1), the polarity of the resin component changes before and after exposure, and only by the alkali development process. However, even in the solvent development process, good development contrast can be obtained between the exposed portion and the unexposed portion of the resist film.

In the case of applying an alkali development process, the component (A1) is poorly soluble in an alkali developer before exposure, and for example, when an acid is generated from the component (B) upon exposure, the polarity causes the action of the acid It increases to increase the solubility in an alkaline developer. Therefore, in the formation of a resist pattern, when the resist film obtained by applying the resist composition on a support is selectively exposed, the exposed portion of the resist film changes from being poorly soluble to soluble in an alkaline developer. On the other hand, since the unexposed area of the resist film does not change with the alkali solubility, a positive resist pattern is formed by alkali development.
On the other hand, when a solvent development process is applied, the component (A1) has high solubility in an organic developer before exposure, for example, when an acid is generated from the component (B) upon exposure, the action of the acid As a result, the polarity is increased and the solubility in the organic developer is decreased. Therefore, if the resist film obtained by applying the resist composition onto a support is selectively exposed to light in the formation of a resist pattern, the exposed portion of the resist film becomes soluble or poorly soluble in an organic developer. Since the resist film unexposed area remains soluble while changing, a negative resist pattern is formed by developing with an organic developer.

・ Constituent unit (a10):
The structural unit (a10) is a structural unit represented by the following general formula (a10-1).

In the formula (a10-1), R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms.
The alkyl group having 1 to 5 carbon atoms for R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, n- Examples include butyl, isobutyl, tert-butyl, pentyl, isopentyl and neopentyl. The halogenated alkyl group of 1 to 5 carbon atoms for R is a group in which part or all of the hydrogen atoms of the alkyl group for 1 to 5 carbon atoms are substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is particularly preferable.
As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methyl group is most preferable from the viewpoint of industrial availability.

In the formula (a10-1), Ya ^x1 is a single bond or a divalent linking group.
Preferred examples of the divalent linking group in Ya ^x1 include a divalent hydrocarbon group which may have a substituent and a divalent linking group containing a hetero atom.

・ Divalent hydrocarbon group which may have a substituent:
When ^Yax1 is a divalent hydrocarbon group which may have a substituent, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

Aliphatic hydrocarbon group in Ya ^{x 1} The aliphatic hydrocarbon group means a hydrocarbon group having no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, and is usually preferably saturated.
Examples of the aliphatic hydrocarbon group include linear or branched aliphatic hydrocarbon groups, and aliphatic hydrocarbon groups having a ring in the structure.

.... Linear or branched aliphatic hydrocarbon group The linear aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, The number 1 to 4 is more preferable, and the number of carbons 1 to 3 is most preferable.
As a linear aliphatic hydrocarbon group, a linear alkylene group is preferable, and specifically, a methylene group [-CH _2- ], an ethylene group [-(CH ₂ ) _2- ], a trimethylene group [ _{_{- (CH 2) 3 -]}} , a tetramethylene group _{_{[- (CH 2) 4 -}} ], a pentamethylene group _{_{[- (CH 2) 5 -}} ] , and the like.
The branched aliphatic hydrocarbon group preferably has 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.
As the branched aliphatic hydrocarbon group, preferably a branched chain alkylene group, _{_{specifically, -CH (CH 3) -,}} - CH (CH 2 CH 3) -, - C (CH 3) _{_{_{_{2 -, - C (CH 3}}}} ) (CH 2 CH 3) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as - _{_{_{_{CH (CH 3) CH 2 -}}}} , - CH (CH 3) CH (CH 3) -, - C (CH 3) 2 CH 2 -, - CH (CH 2 CH 3) CH 2 -, - C (CH 2 CH ₃₎ ₂ -CH ₂ - alkyl groups such _{_{_{as; -CH (CH 3) CH 2}}} CH 2 -, - CH 2 CH (CH 3) CH 2 - alkyl trimethylene groups such as; -CH _(CH 3) _{_{_{_{CH 2 CH 2 CH 2 -,}}}} - CH 2 CH (CH 3) CH 2 CH 2 - And the like alkyl alkylene group such as an alkyl tetramethylene group of. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

The linear or branched aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group of 1 to 5 carbon atoms substituted with a fluorine atom, and a carbonyl group.

... Alphatic hydrocarbon group containing a ring in the structure As the aliphatic hydrocarbon group containing a ring in the structure, a cyclic aliphatic hydrocarbon group which may contain a substituent containing a hetero atom in the ring structure (A group in which two hydrogen atoms have been removed from an aliphatic hydrocarbon ring), a group in which the cyclic aliphatic hydrocarbon group is bonded to the end of a linear or branched aliphatic hydrocarbon group, the cyclic fat And the like, and groups in which a group hydrocarbon group intervenes in a linear or branched aliphatic hydrocarbon group are exemplified. Examples of the linear or branched aliphatic hydrocarbon group include the same as described above.
The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.
The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. As a monocyclic alicyclic hydrocarbon group, a group obtained by removing two hydrogen atoms from a monocycloalkane is preferable. The monocycloalkane is preferably one having 3 to 6 carbon atoms, and specific examples include cyclopentane, cyclohexane and the like. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a polycycloalkane, and as the polycycloalkane, one having 7 to 12 carbon atoms is preferable, and specifically, Examples include adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like.

The cyclic aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group and the like.
The alkyl group as the substituent is preferably an alkyl group having a carbon number of 1 to 5, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group or a tert-butyl group.
The alkoxy group as the substituent is preferably an alkoxy group having a carbon number of 1 to 5, and more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group or a tert-butoxy group. Methoxy and ethoxy are most preferred.
As a halogen atom as the said substituent, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, A fluorine atom is preferable.
As a halogenated alkyl group as said substituent, the group by which one part or all part of the hydrogen atom of the said alkyl group was substituted by the said halogen atom is mentioned.
In the cyclic aliphatic hydrocarbon group, a part of carbon atoms constituting the ring structure may be substituted with a substituent containing a hetero atom. The substituent containing a hetero atom, -O -, - C (= O) -O -, - S -, - S (= O) 2 -, - S (= O) 2 -O- are preferred.

Aromatic hydrocarbon group in Ya ^{x 1} The aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.
The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having 4n + 2 π electrons, and may be monocyclic or polycyclic. The carbon number of the aromatic ring is preferably 5 to 30, more preferably 5 to 20, still more preferably 6 to 15, and particularly preferably 6 to 12. However, the carbon number does not include the carbon number in the substituent. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene and phenanthrene; and aromatic heterocyclic rings in which a part of carbon atoms constituting the aromatic hydrocarbon ring is substituted with a hetero atom, etc. It can be mentioned. Examples of the hetero atom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom.
Specific examples of the aromatic heterocycle include a pyridine ring and a thiophene ring.
Specifically, as the aromatic hydrocarbon group, a group obtained by removing two hydrogen atoms from the aromatic hydrocarbon ring or the aromatic heterocycle (arylene group or heteroarylene group); an aromatic compound containing two or more aromatic rings A group obtained by removing two hydrogen atoms from (eg biphenyl, fluorene etc.); one hydrogen atom of a group (aryl group or heteroaryl group) obtained by removing one hydrogen atom from the aromatic hydrocarbon ring or aromatic heterocycle Hydrogen atoms from the aryl group in arylalkyl groups such as benzyl, phenethyl, 1-naphthylmethyl, 2-naphthylmethyl, 1-naphthylethyl, 2-naphthylethyl and the like; And the like) and the like. The carbon number of the alkylene group bonded to the aryl group or heteroaryl group is preferably 1 to 4, more preferably 1 to 2 carbon atoms, and particularly preferably 1 carbon atom.

In the aromatic hydrocarbon group, the hydrogen atom of the aromatic hydrocarbon group may be substituted by a substituent. For example, a hydrogen atom bonded to an aromatic ring in the aromatic hydrocarbon group may be substituted by a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group and the like.
The alkyl group as the substituent is preferably an alkyl group having a carbon number of 1 to 5, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group or a tert-butyl group.
As the alkoxy group, the halogen atom and the halogenated alkyl group as the substituent, those exemplified as the substituent for substituting the hydrogen atom of the cyclic aliphatic hydrocarbon group can be mentioned.

・ Divalent linking group containing hetero atom:
When Ya ^x1 is a divalent linking group containing a hetero atom, preferred as the linking group are -O-, -C (= O) -O-, -C (= O)-, -O-C. (= O) -O-, -C (= O) -NH-, -NH-, -NH-C (= NH)-(H may be substituted with a substituent such as an alkyl group or an acyl group _{.), - S -, -} S (= O) 2 -, - S (= O) 2 -O-, the formula ^{^{^{-Y 21 -O-Y 22 -,}}} - Y 21 -O -, - Y 21 - ^{C (= O) -O -,} - C (= O) -O-Y 21 -, - [Y 21 -C (= O) -O] m "-Y 22 -, - Y 21 -O-C ( A group represented by OO) -Y ²² -or -Y ²¹ -S (= O) ₂ -O-Y ²² -wherein Y ²¹ and Y ²² each independently have a substituent It is also a good divalent hydrocarbon group, It is an oxygen atom, m "is an integer of 0-3. Etc.
The aforementioned divalent linking group containing a heteroatom is -C (= O) -NH-, -C (= O) -NH-C (= O)-, -NH-, -NH-C (= NH) In the case of-), the H may be substituted by a substituent such as an alkyl group or an acyl group. The substituent (such as an alkyl group or an acyl group) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 5 carbon atoms.
Formula ^{^{^{^{-Y 21 -O-Y 22 -,}}}} - Y 21 -O -, - Y 21 -C (= O) -O -, - C (= O) -O-Y 21 -, - [Y 21 - _{^{^{C (= O) -O] m}}} "-Y 22 -, - Y 21 -O-C (= O) -Y 22 - or ^{_{-Y 21 -S (= O) 2}} -O-Y 22 - in, Y ²¹ and Y ²² each independently represents a divalent hydrocarbon group which may have a substituent, and as the divalent hydrocarbon group, it is mentioned in the explanation as the divalent linking group. And the same groups as those described above (the bivalent hydrocarbon group which may have a substituent).
As Y ²¹ , a linear aliphatic hydrocarbon group is preferable, a linear alkylene group is more preferable, a linear alkylene group having 1 to 5 carbon atoms is further preferable, and a methylene group or an ethylene group is particularly preferable preferable.
As Y ²² , a linear or branched aliphatic hydrocarbon group is preferable, and a methylene group, an ethylene group or an alkylmethylene group is more preferable. The alkyl group in the alkylmethylene group is preferably a linear alkyl group of 1 to 5 carbon atoms, more preferably a linear alkyl group of 1 to 3 carbon atoms, and most preferably a methyl group.
Formula ^{_{- [Y 21 -C (= O}} ) -O] m "-Y 22 - In the group represented by, m" is an integer of 0 to 3, preferably an integer of 0 to 2, 0 or 1 is more preferable, and 1 is particularly preferable. In other words, the formula ^- Examples of the group represented by the formula ^{-Y 21 -C (= O) -O} -Y 22 - - [Y 21 -C (= O) -O] m "-Y 22 represented by group is particularly preferred among them, the formula _{_{-. (CH 2) a '}} -C (= O) -O- (CH 2) b' -. in the group represented by the formula in the formula, a 'is from 1 to 10 The integer of 1 to 8 is preferable, the integer of 1 to 5 is more preferable, 1 or 2 is more preferable, and 1 is most preferable. B ′ is an integer of 1 to 10, 1 to 8 An integer is preferred, an integer of 1 to 5 is more preferred, 1 or 2 is more preferred, and 1 is most preferred.

As Ya ^x1 , a single bond, an ester bond [—C (OO) —O—], an ether bond (—O—), —C (= O) —NH—, a linear or branched alkylene group It is preferable that it is or these combination, and in particular a single bond is more preferable.

In the formula (a10-1), Wa ^x1 is an (n _ax1 +1) _-valent aromatic hydrocarbon group.
The aromatic hydrocarbon group for Wa ^x1, include groups obtained by removing from an aromatic ring of the _(n ax1 +1) number of hydrogen atoms. The aromatic ring here is not particularly limited as long as it is a cyclic conjugated system having 4n + 2 π electrons, and may be monocyclic or polycyclic. The carbon number of the aromatic ring is preferably 5 to 30, more preferably 5 to 20, still more preferably 6 to 15, and particularly preferably 6 to 12. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene and phenanthrene; and aromatic heterocyclic rings in which a part of carbon atoms constituting the aromatic hydrocarbon ring is substituted with a hetero atom, etc. It can be mentioned. Examples of the hetero atom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocycle include a pyridine ring and a thiophene ring.

In the formula (a10-1), n _ax1 is an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

Hereinafter, specific examples of the structural unit represented by the general formula (a10-1) will be shown.
In the following formulae, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

The structural unit (a10) contained in the component (A1) may be one type or two or more types.
Among the above, as the structural unit (a10), a structural unit containing a hydroxystyrene skeleton is preferable, and a structural unit represented by the following general formula (a10-1-0) is particularly preferable.

[Wherein, R ^st represents a hydrogen atom or a methyl group. m ₀₁ represents an integer of 1 to 3; ]

The proportion of the structural unit (a10) in the component (A1) is preferably 40 to 80 mol%, more preferably 45 to 75 mol%, based on the total (100 mol%) of all structural units constituting the component (A1). Is more preferable, and 50 to 70 mol% is particularly preferable.
By setting the ratio of the structural unit (a10) to the lower limit value of the preferable range or more, the sensitivity, the development characteristics, the effect of suppressing the occurrence of defects and the like are further improved, and on the other hand, the upper limit value of the preferable range Thereby, lithography properties such as dimensional uniformity are further improved.

・ Constituent unit (a4):
The structural unit (a4) is a structural unit containing a non-acid dissociable, aliphatic cyclic group.
When the component (A1) has the structural unit (a4), the light transmittance of the resist film is enhanced as compared with the case where the structural unit containing an aromatic cyclic group is contained. In addition, the dry etching resistance of the formed resist pattern is improved, and in addition, the hydrophobicity of the component (A) is increased. The improvement of the hydrophobicity contributes to the improvement of the resolution, the shape of the resist pattern, and the like particularly in the case of forming the resist pattern by the solvent development process.
The “non-acid dissociable cyclic group” in the structural unit (a4) is an acid when generated in the resist composition upon exposure (for example, when an acid is generated from the component (B) described later), the acid It is a cyclic group which remains as it is in the structural unit without dissociation even if.

The non-acid dissociable, aliphatic cyclic group in the structural unit (a4) may be a monocyclic group or a polycyclic group, preferably a monocyclic group.
As a monocyclic group here, a group obtained by removing one or more hydrogen atoms from a monocycloalkane is preferable. The monocycloalkane is preferably one having 3 to 8 carbon atoms, more preferably one having 5 to 8 carbon atoms, and specific examples include cyclopentane, cyclohexane, cyclooctane and the like. The polycyclic group here is preferably a group obtained by removing one or more hydrogen atoms from polycycloalkane, and as the polycycloalkane, one having 7 to 12 carbon atoms is preferable, and specifically, adamantane, And norbornane, isobornane, tricyclodecane, tetracyclododecane and the like.
The monocyclic group and polycyclic group each may have, for example, a linear or branched alkyl group having 1 to 5 carbon atoms as a substituent.

Examples of the structural unit (a4) include a structural unit derived from an acrylic ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted with a substituent, a structural unit derived from acrylamide, etc. A structural unit derived from an acrylic ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted with a substituent is preferred.

Below, the specific example of a structural unit (a4) is shown.
In the following formulae, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

The structural unit (a4) contained in the component (A1) may be of one type or of two or more types.
Among the above, the structural unit (a4) is preferably a structural unit which is non-acid dissociable and contains a monocyclic aliphatic cyclic group, and any of the chemical formulas (a4-7) to (a4-10). More preferred is at least one selected from the group consisting of structural units represented by か.

The proportion of the structural unit (a4) in the component (A1) is preferably 1 to 50 mol%, based on the total (100 mol%) of all the structural units constituting the component (A1), 50 mol% is more preferable, and 5 to 45 mol% is more preferable.
By setting the ratio of the structural unit (a4) to the lower limit value of the above-mentioned preferable range or more, the light transmittance of the resist film is further enhanced, thereby achieving higher sensitivity and resolution improvement. On the other hand, by setting the content to the upper limit value of the above-mentioned preferable range or less, it becomes easy to balance with other structural units.

・ About the composition unit (a1):
The structural unit (a1) is a structural unit containing an acid-degradable group whose polarity is increased by the action of an acid.
The "acid-degradable group" is a group having acid-degradability which can cleave at least a part of bonds in the structure of the acid-degradable group by the action of an acid.
Examples of the acid-degradable group whose polarity is increased by the action of an acid include, for example, a group which is decomposed by the action of an acid to generate a polar group.
Examples of the polar group include a carboxy group, a hydroxyl group, an amino group and a sulfo group (-SO ₃ H). Among these, a polar group containing —OH in the structure (hereinafter sometimes referred to as “OH-containing polar group”) is preferable, a carboxy group or a hydroxyl group is more preferable, and a carboxy group is particularly preferable.
More specifically, examples of the acid-degradable group include a group in which the polar group is protected by an acid dissociable group (for example, a group in which a hydrogen atom of an OH-containing polar group is protected by an acid dissociable group).
Here, the “acid dissociable group” is (i) a group having an acid dissociability that can cleave the bond between the acid dissociable group and the atom adjacent to the acid dissociable group by the action of an acid; Or (ii) after a partial bond is cleaved by the action of an acid, a decarboxylation reaction is further caused to cleave the bond between the acid dissociable group and the atom adjacent to the acid dissociable group It refers to both of the obtained groups.
The acid dissociable group constituting the acid decomposable group is required to be a group having a polarity lower than that of the polar group generated by the dissociation of the acid dissociable group, whereby the acid dissociable group is formed by the action of an acid. When dissociates, a polar group having a polarity higher than that of the acid-dissociable group is generated to increase the polarity. As a result, the polarity of the entire component (A1) is increased. The increase in polarity relatively changes the solubility in the developer, the solubility increases when the developer is an alkaline developer, and the solubility when the developer is an organic developer. Decrease.

Examples of the acid dissociable group include those which have been proposed as acid dissociable groups of base resins for chemically amplified resist compositions.
Specific examples of the acid dissociable group of the base resin for a chemically amplified resist composition include the "acetal-type acid dissociable group" and the "tertiary alkyl ester-type acid dissociable group" described below. And "tertiary alkyloxycarbonyl acid dissociable group".

・ Acetal type acid dissociable group:
As an acid dissociative group which protects a carboxy group or a hydroxyl group among the said polar groups, the acid dissociative group (following "acetal type acid dissociative group" represented by the following general formula (a1-r-1) is called, for example) May be mentioned).

[Wherein, Ra ′ ¹ and Ra ′ ² are a hydrogen atom or an alkyl group, Ra ′ ³ is a hydrocarbon group, and Ra ′ ³ is bonded to any of Ra ′ ¹ and Ra ′ ² to form a ring May be formed. ]

In formula (a1-r-1), at least one of Ra ′ ¹ and Ra ′ ² is preferably a hydrogen atom, and more preferably both are a hydrogen atom.
When Ra ′ ¹ or Ra ′ ² is an alkyl group, examples of the alkyl group include the alkyl groups mentioned as the substituent which may be bonded to the carbon atom at the α position in the description of the α-substituted acrylic acid ester. The same thing is mentioned, and a C1-C5 alkyl group is preferable. Specifically, a linear or branched alkyl group is preferably mentioned. More specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like can be mentioned, and methyl group or ethyl group is More preferred is methyl group.

In formula (a1-r-1), examples of the hydrocarbon group of Ra ′ ³ include a linear or branched alkyl group, or a cyclic hydrocarbon group.
The linear alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 and still more preferably 1 or 2. Specifically, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group and the like can be mentioned. Among these, a methyl group, an ethyl group or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.

The branched alkyl group preferably has 3 to 10 carbon atoms, and more preferably 3 to 5 carbon atoms. Specifically, isopropyl group, isobutyl group, tert-butyl group, isopentyl group, neopentyl group, 1,1-diethylpropyl group, 2,2-dimethylbutyl group and the like can be mentioned, with preference given to isopropyl group.

When Ra ′ ³ is a cyclic hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and may be a polycyclic group or a monocyclic group.
As an aliphatic hydrocarbon group which is a monocyclic group, a group in which one hydrogen atom is removed from a monocycloalkane is preferable. The monocycloalkane is preferably one having 3 to 6 carbon atoms, and specific examples include cyclopentane, cyclohexane and the like.
The aliphatic hydrocarbon group which is a polycyclic group is preferably a group obtained by removing one hydrogen atom from a polycycloalkane, and as the polycycloalkane, one having 7 to 12 carbon atoms is preferable, and specifically And adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like.

When the cyclic hydrocarbon group of Ra ′ ³ is an aromatic hydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.
The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having 4n + 2 π electrons, and may be monocyclic or polycyclic. The carbon number of the aromatic ring is preferably 5 to 30, more preferably 5 to 20, still more preferably 6 to 15, and particularly preferably 6 to 12.
Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene and phenanthrene; and aromatic heterocyclic rings in which a part of carbon atoms constituting the aromatic hydrocarbon ring is substituted with a hetero atom, etc. It can be mentioned. Examples of the hetero atom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocycle include a pyridine ring and a thiophene ring.
Specific examples of the aromatic hydrocarbon group in ra ^'3, the aromatic hydrocarbon ring or one hydrogen atom from an aromatic heterocyclic group formed by removing (aryl or heteroaryl); two or more aromatic rings A group obtained by removing one hydrogen atom from an aromatic compound (eg, biphenyl, fluorene etc.) containing; a group in which one hydrogen atom of the aromatic hydrocarbon ring or aromatic heterocycle is substituted with an alkylene group (eg, a benzyl group) And arylalkyl groups such as phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group, 2-naphthylethyl group and the like). The carbon number of the alkylene group bonded to the aromatic hydrocarbon ring or aromatic heterocycle is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

When Ra ′ ³ combines with any of Ra ′ ¹ and Ra ′ ² to form a ring, the cyclic group is preferably a 4 to 7-membered ring, and more preferably a 4 to 6-membered ring. Specific examples of the cyclic group include tetrahydropyranyl group, tetrahydrofuranyl group and the like.

Tertiary alkyl ester type acid dissociable group:
Examples of the acid dissociable group protecting the carboxy group among the polar groups include an acid dissociable group represented by the following general formula (a1-r-2).
Among the acid dissociable groups represented by the following formula (a1-r-2), those composed of alkyl groups may be hereinafter referred to as “tertiary alkyl ester type acid dissociable groups” for the sake of convenience. .

[Wherein, each of Ra ′ ⁴ to Ra ′ ⁶ is a hydrocarbon group, and Ra ′ ⁵ and Ra ′ ⁶ may be bonded to each other to form a ring. ]

Examples of the hydrocarbon group of Ra ′ ⁴ to Ra ′ ⁶ include the same as the aforementioned Ra ′ ³ .
Ra ′ ⁴ is preferably an alkyl group having 1 to 5 carbon atoms. If Ra and ^'5 and Ra' ⁶ are bonded to each other to form a ring, a group represented by the following general formula (a1-r2-1). On the other hand, when Ra ′ ⁴ to Ra ′ ⁶ do not bind to each other and are independent hydrocarbon groups, groups represented by general formula (a1-r2-2) shown below can be mentioned.

[Wherein, Ra ′ ¹⁰ is an alkyl group having 1 to 10 carbon atoms, Ra ′ ¹¹ is a group forming an aliphatic cyclic group with a carbon atom to which Ra ′ ¹⁰ is bonded, and Ra ′ ¹² to Ra ′ ¹⁴ are each It independently represents a hydrocarbon group. ]

In Formula (a1-r2-1), the alkyl group having 1 to 10 carbon atoms of Ra ′ ¹⁰ is exemplified as the linear or branched alkyl group of Ra ′ ³ in Formula (a1-r-1) Groups are preferred.
In the formula (a1-r2-1), the aliphatic cyclic group formed together with the carbon atom to which Ra ′ ¹¹ and Ra ′ ¹⁰ are bonded is a monocyclic group of Ra ′ ³ in the formula (a1-r-1) Or the group mentioned as an aliphatic hydrocarbon group which is a polycyclic group is preferable, and the group mentioned as an aliphatic hydrocarbon group which is a monocyclic group is more preferable.

In the formula (a1-r2-2), it is preferable that each of Ra ′ ¹² and Ra ′ ^{14 be} each independently an alkyl group having 1 to 10 carbon atoms, and the alkyl group is a group represented by formula (a1-r-1) The group mentioned as the linear or branched alkyl group of Ra ′ ³ is more preferable, a C 1-5 linear alkyl group is more preferable, and a methyl group or an ethyl group is particularly preferable. preferable.
In formula (a1-r2-2), Ra ′ ¹³ is a linear or branched alkyl group or monocyclic group exemplified as the hydrocarbon group of Ra ′ ³ in formula (a1-r-1) It is preferably an aliphatic hydrocarbon group which is a polycyclic group. Among these, groups described as aliphatic hydrocarbon groups which are monocyclic groups or polycyclic groups of Ra ′ ³ are more preferable.

Specific examples of the group represented by the above formula (a1-r2-1) are given below. The symbol * indicates a bond (the same applies throughout the present specification).

Specific examples of the group represented by the formula (a1-r2-2) will be given below.

Tertiary alkyloxycarbonyl acid dissociable group:
As the acid dissociable group for protecting the hydroxyl group among the polar groups, for example, an acid dissociable group represented by the following general formula (a1-r-3) (hereinafter, for convenience, “tertiary alkyloxycarbonyl acid dissociable group” There is a case where

[Wherein, each of Ra ′ ⁷ to Ra ′ ⁹ is an alkyl group. ]

In the formula (a1-r-3), each of Ra ′ ⁷ to Ra ′ ⁹ is preferably an alkyl group having a carbon number of 1 to 5, and more preferably 1 to 3.
The total carbon number of each alkyl group is preferably 3 to 7, more preferably 3 to 5, and most preferably 3 to 4.

Among the above, the acid decomposable group in the structural unit (a1) is preferably a group containing an aliphatic cyclic group, since the decomposability by the action of an acid is higher, and an acid dissociable group containing an aliphatic cyclic group Groups in which a polar group (carboxy group, hydroxyl group, amino group, sulfo group etc.) is protected are more preferable. Among these, the acid-decomposable group in the structural unit (a1) is represented by the above general formula (a1-r2-1) because the resolution is improved and a pattern having a better shape is easily formed. A group containing an acid dissociable group is preferable, and a group containing an acid dissociable group represented by the following general formula (a1-r2-11) is more preferable.

[Wherein, Ra ′ ¹⁰ is a hydrocarbon group having 1 to 10 carbon atoms. Ra ′ ′ ¹¹ is a group which forms a monocyclic aliphatic cyclic group together with the carbon atom to which Ra ′ ¹⁰ is bonded. * Is a bond.]

Formula (a1-r2-11) in, Ra 'alkyl group having a carbon number of ¹⁰ 1-10, Ra in formula (a1-r-1)' was mentioned as linear or branched alkyl group of ³ Groups are preferred.
The linear alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 and still more preferably 1 or 2. Specifically, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group and the like can be mentioned. Among these, a methyl group, an ethyl group or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.
The branched alkyl group preferably has 3 to 10 carbon atoms, and more preferably 3 to 5 carbon atoms. Specifically, isopropyl group, isobutyl group, tert-butyl group, isopentyl group, neopentyl group, 1,1-diethylpropyl group, 2,2-dimethylbutyl group and the like can be mentioned, with preference given to isopropyl group.

In the formula (a1-r2-11), the aliphatic cyclic group formed together with the carbon atom to which Ra ′ ′ ¹¹ and Ra ′ ¹⁰ are bonded is a monocyclic group of Ra ′ ³ in the formula (a1-r-1) The group mentioned as an aliphatic hydrocarbon group which is
As an aliphatic hydrocarbon group which is a monocyclic group, a group in which one hydrogen atom is removed from a monocycloalkane is preferable. As the monocycloalkane, one having 3 to 8 carbon atoms is preferable, one having 3 to 6 carbon atoms is more preferable, and specific examples include cyclopentane, cyclohexane and the like.

As the structural unit (a1), a structural unit derived from an acrylic ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted with a substituent, a structural unit derived from acrylamide, hydroxystyrene or hydroxy A structural unit in which at least a part of hydrogen atoms in a hydroxyl group of a structural unit derived from a styrene derivative is protected by an acid dissociable group, -C (= O) of a structural unit derived from vinylbenzoic acid or a vinylbenzoic acid derivative Examples include structural units in which at least a part of hydrogen atoms in —OH is protected by an acid dissociable group.

Among the above, as the structural unit (a1), a structural unit derived from an acrylic acid ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted with a substituent is preferable.
Specific preferred examples of the structural unit (a1) include structural units represented by general formula (a1-1) or general formula (a1-2) shown below.

Wherein R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms. Va ¹ is a divalent hydrocarbon group which may have an ether bond, n _a1 is 0 to 2, and Ra ¹ is the above formula (a1-r-1) or (a1-r-2) It is an acid dissociable group represented by Wa ¹ is an n _a2 + 1-valent hydrocarbon group, n _a2 is 1 to 3, and Ra ² is an acid dissociable represented by the above formula (a1-r-1) or (a1-r-3) It is a group. ]

In the above formula (a1-1), the alkyl group having 1 to 5 carbon atoms of R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically, a methyl group or an ethyl group And propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl and the like. The halogenated alkyl group having 1 to 5 carbon atoms is a group in which part or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is particularly preferable.
As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methyl group is most preferable from the viewpoint of industrial availability.

In the formula (a1-1), the divalent hydrocarbon group at Va ¹ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

The aliphatic hydrocarbon group as a bivalent hydrocarbon group in Va ¹ may be saturated or unsaturated, and is usually preferably saturated.
More specific examples of the aliphatic hydrocarbon group include linear or branched aliphatic hydrocarbon groups, and aliphatic hydrocarbon groups containing a ring in the structure.

The linear or branched aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.
As a linear aliphatic hydrocarbon group, a linear alkylene group is preferable, and specifically, a methylene group [-CH _2- ], an ethylene group [-(CH ₂ ) _2- ], a trimethylene group [ _{_{- (CH 2) 3 -]}} , a tetramethylene group _{_{[- (CH 2) 4 -}} ], a pentamethylene group _{_{[- (CH 2) 5 -}} ] , and the like.
As the branched aliphatic hydrocarbon group, preferably a branched chain alkylene group, _{_{specifically, -CH (CH 3) -,}} - CH (CH 2 CH 3) -, - C (CH 3) _{_{_{_{2 -, - C (CH 3}}}} ) (CH 2 CH 3) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as - _{_{_{_{CH (CH 3) CH 2 -}}}} , - CH (CH 3) CH (CH 3) -, - C (CH 3) 2 CH 2 -, - CH (CH 2 CH 3) CH 2 -, - C (CH 2 CH ₃₎ ₂ -CH ₂ - alkyl groups such _{_{_{as; -CH (CH 3) CH 2}}} CH 2 -, - CH 2 CH (CH 3) CH 2 - alkyl trimethylene groups such as; -CH _(CH 3) _{_{_{_{CH 2 CH 2 CH 2 -,}}}} - CH 2 CH (CH 3) CH 2 CH 2 - And the like alkyl alkylene group such as an alkyl tetramethylene group of. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

As an aliphatic hydrocarbon group which contains a ring in the said structure, alicyclic hydrocarbon group (The group which remove | eliminated two hydrogen atoms from the aliphatic hydrocarbon ring), and an alicyclic hydrocarbon group are linear or branched Examples thereof include a group bonded to the end of a linear aliphatic hydrocarbon group, and a group in which an alicyclic hydrocarbon group intervenes in the middle of a linear or branched aliphatic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include the same as the linear aliphatic hydrocarbon group or the branched aliphatic hydrocarbon group.
The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.
The alicyclic hydrocarbon group may be polycyclic or monocyclic. As a monocyclic alicyclic hydrocarbon group, a group obtained by removing two hydrogen atoms from a monocycloalkane is preferable. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples include cyclopentane, cyclohexane and the like. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a polycycloalkane, and as the polycycloalkane, one having 7 to 12 carbon atoms is preferable, and specifically, adamantane , Norbornane, isobornane, tricyclodecane, tetracyclododecane and the like.

The aromatic hydrocarbon group as a bivalent hydrocarbon group in Va ¹ is a hydrocarbon group having an aromatic ring.
The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, still more preferably 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to 10 carbon atoms. . However, the carbon number does not include the carbon number in the substituent.
Specifically as an aromatic ring which an aromatic hydrocarbon group has, aromatic hydrocarbon rings, such as benzene, biphenyl, fluorene, naphthalene, anthracene, phenanthrene etc; some carbon atoms which comprise the said aromatic hydrocarbon ring are hetero The aromatic heterocyclic ring etc. which were substituted by the atom are mentioned. Examples of the hetero atom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom.
Specifically, as the aromatic hydrocarbon group, a group in which two hydrogen atoms are removed from the aromatic hydrocarbon ring (arylene group); a group in which one hydrogen atom is removed from the aromatic hydrocarbon ring (aryl group And arylalkyls such as benzyl, phenethyl, 1-naphthylmethyl, 2-naphthylmethyl, 1-naphthylethyl, 2-naphthylethyl and the like (for example, benzyl, phenethyl, 1-naphthylmethyl, 2-naphthylmethyl, 1-naphthylethyl) And the like) and the like in which one hydrogen atom is further removed from the aryl group in the group. The carbon number of the alkylene group (the alkyl chain in the arylalkyl group) is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

In the formula (a1-2), the n _a2 + 1-valent hydrocarbon group in Wa ¹ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group having no aromaticity, which may be saturated or unsaturated, and is preferably saturated. As the aliphatic hydrocarbon group, a linear or branched aliphatic hydrocarbon group, an aliphatic hydrocarbon group containing a ring in the structure, or a linear or branched aliphatic hydrocarbon group The group which combined the aliphatic hydrocarbon group containing a ring in a structure is mentioned.
The n _a2 +1 valence is preferably a divalent to tetravalent, more preferably a divalent or trivalent.

Specific examples of the structural unit represented by the formula (a1-1) are shown below. In each of the following formulas, R ^α represents a hydrogen atom, a methyl group or a trifluoromethyl group.

Hereinafter, specific examples of the constituent unit represented by the formula (a1-2) will be shown.

Among the structural units (a1), structural units represented by general formula (a1-1) above are more preferable, and among these, structural units represented by general formula (a1-1), structural units ra ¹ is an acid labile group represented by the formula (a1-r2-11) is particularly preferred.

The structural unit (a1) contained in the component (A1) may be one type or two or more types.
The proportion of the structural unit (a1) in the component (A1) is preferably 5 to 20 mol%, more preferably 7 to 20 mol%, with respect to the total structural units (100 mol%) constituting the component (A1). 10 to 20 mol% is more preferable.
By setting the ratio of the structural unit (a1) to the lower limit value of the preferable range or more, a resist pattern can be easily obtained, the resolution is further improved, and a pattern having a good shape is easily formed. Become. Further, by setting the upper limit value or less, it is possible to balance with other constituent units.

・ About other constituent units:
The component (A1) may have other structural units as necessary in addition to the structural unit (a10), the structural unit (a4) and the structural unit (a1).
As the other structural unit, for example, a structural unit (a2) containing a lactone-containing cyclic group, a —SO ₂ -containing cyclic group or a carbonate-containing cyclic group; a structural unit (a3) containing a polar group-containing aliphatic hydrocarbon group (However, except for those corresponding to the structural unit (a1) or the structural unit (a2)); Structural units derived from styrene or a derivative thereof, and the like can be mentioned.

.. Constitutional unit (a2)
The component (A1) is added to the structural unit (a10), the structural unit (a4) and the structural unit (a1), and, if necessary, a lactone-containing cyclic group, -SO ₂ -containing cyclic group or carbonate-containing compound It may have a structural unit (a2) containing a cyclic group.
The lactone-containing cyclic group, the --SO ₂ -containing cyclic group or the carbonate-containing cyclic group of the structural unit (a2) adheres to the substrate of the resist film when the component (A1) is used to form a resist film. It is effective in enhancing the sex. Further, by having the structural unit (a2), in the alkali development process, the solubility of the resist film in an alkali developer can be enhanced at the time of development.

The “lactone-containing cyclic group” refers to a cyclic group containing a ring (lactone ring) containing —O—C (= O) — in the ring skeleton thereof. The lactone ring is counted as the first ring, and when it has only a lactone ring, it is a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of its structure. The lactone-containing cyclic group may be a monocyclic group or a polycyclic group.
The lactone-containing cyclic group in the structural unit (a2) is not particularly limited, and any group can be used. Specific examples thereof include groups represented by general formulas (a2-r-1) to (a2-r-7) shown below.

Wherein, Ra ^'21 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, hydroxyl group, -COOR ", - OC (= O) R", a hydroxyalkyl group or a cyano R ′ ′ is a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO ₂ -containing cyclic group. A ′ ′ is an oxygen atom (—O—) or a sulfur atom It is an alkylene group having 1 to 5 carbon atoms which may contain (—S—), an oxygen atom or a sulfur atom. n 'is an integer of 0 to 2, and m' is 0 or 1. ]

In the formulas (a2-r-1) to (a2-r-7), as the alkyl group for Ra ′ ^21, an alkyl group having 1 to 6 carbon atoms is preferable. The alkyl group is preferably linear or branched. Specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group and the like can be mentioned. Among these, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.
The alkoxy group in Ra ′ ²¹ is preferably an alkoxy group having 1 to 6 carbon atoms.
The alkoxy group is preferably linear or branched. Specifically, a group in which an alkyl group mentioned as the alkyl group in the aforementioned Ra ′ ²¹ and an oxygen atom (—O—) are connected is mentioned.
As the halogen atom in ra ^'21, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a fluorine atom is preferable.
'Examples of the halogenated alkyl group for ^21, the Ra' Ra some or all of the hydrogen atoms of the alkyl group in ²¹ can be mentioned have been substituted with the aforementioned halogen atoms. As the halogenated alkyl group, a fluorinated alkyl group is preferable, and a perfluoroalkyl group is particularly preferable.

Ra '-COOR in ^{21 ", - OC (= O} ) R" in, R "is also hydrogen either is an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or -SO ₂ - containing cyclic group It is.
The alkyl group in R ′ ′ may be linear, branched or cyclic, and preferably has 1 to 15 carbon atoms.
When R ′ ′ is a linear or branched alkyl group, it preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and particularly preferably a methyl group or an ethyl group. preferable.
When R ′ ′ is a cyclic alkyl group, it preferably has 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and still more preferably 5 to 10 carbon atoms. Or a group obtained by removing one or more hydrogen atoms from a monocycloalkane which may or may not be substituted with a fluorinated alkyl group; polycycloalkanes such as bicycloalkanes, tricycloalkanes and tetracycloalkanes Groups in which one or more hydrogen atoms have been removed, etc. More specifically, groups in which one or more hydrogen atoms have been removed from a monocycloalkane such as cyclopentane, cyclohexane and the like; adamantane, norbornane, isobornane, tri Groups obtained by removing one or more hydrogen atoms from polycycloalkanes such as cyclodecane and tetracyclododecane That.
As the lactone-containing cyclic group for R ′ ′, the same groups as those represented by the general formulas (a2-r-1) to (a2-r-7) can be mentioned.
The carbonate-containing cyclic group in R ′ ′ is the same as the carbonate-containing cyclic group described later, and specifically, groups represented by general formulas (ax3-r-1) to (ax3-r-3) Can be mentioned.
The containing cyclic group, -SO ₂ below - - -SO ₂ in R "are the same as containing cyclic group, specifically the general formula (a5-r-1) ~ (a5-r-4) And the groups respectively represented by
The hydroxyalkyl group in Ra ′ ²¹ is preferably one having 1 to 6 carbon atoms, and specific examples include a group in which at least one of the hydrogen atoms of the alkyl group in Ra ′ ²¹ is substituted with a hydroxyl group .

In the general formulas (a2-r-2), (a2-r-3) and (a2-r-5), the alkylene group having 1 to 5 carbon atoms in A ′ ′ is a linear or branched alkylene group. An alkylene group is preferable, and a methylene group, an ethylene group, an n-propylene group, an isopropylene group, etc. may be mentioned, When the alkylene group contains an oxygen atom or a sulfur atom, specific examples thereof include the terminal or carbon of the alkylene group between atoms -O- or -S- can be mentioned a group intervening, for example, _{_{_{-O-CH 2 -, - CH}}} 2 -O-CH 2 -, - S-CH 2 -, - CH 2 -S-CH ₂ - such as .A "which include an alkylene group, or -O- is preferable of 1 to 5 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups represented by general formulas (a2-r-1) to (a2-r-7) will be given below.

And _- "-SO 2 containing cyclic group", -SO 2 _- within the ring skeleton thereof shows a cyclic group containing a ring containing, in particular, -SO 2 _- sulfur atom (S) is in It is a cyclic group that forms a part of the ring skeleton of the cyclic group. The ring containing -SO _{2-in the} ring skeleton is counted as the first ring, and in the case of only this ring, it is a monocyclic group, and when it further has another ring structure, a polycyclic group regardless of its structure It is called. The —SO ₂ -containing cyclic group may be a monocyclic group or a polycyclic group.
The —SO ₂ -containing cyclic group is, in particular, a cyclic group containing —O—SO ₂ — in its ring skeleton, ie, —O—S— in —O—SO ₂ — is part of the ring skeleton It is preferable that it is a cyclic group containing a sultone ring which forms
More specifically, examples of the —SO ₂ -containing cyclic group include groups represented by general formulas (a5-r-1) to (a5-r-4) shown below.

Wherein, Ra ^'51 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, hydroxyl group, -COOR ", - OC (= O) R", a hydroxyalkyl group or a cyano It is a group. R ′ ′ is a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO ₂ -containing cyclic group. A ′ ′ is an oxygen atom or a sulfur atom and may have 1 carbon atom And an alkylene group of -5, an oxygen atom or a sulfur atom.
n 'is an integer of 0 to 2. ]

In the general formulas (a5-r-1) to (a5-r-2), A ′ ′ represents the general formulas (a2-r-2), (a2-r-3) and (a2-r-5). It is the same as A "in.
Alkyl group in ra ^'51, an alkoxy group, a halogen atom, a halogenated alkyl group, -COOR ", - OC (= O) R", The hydroxyalkyl group, each of the general formulas (a2-r-1) ~ ( a2-r-7) as in the same as those exemplified in the description of the Ra ^'21 of the like.
Specific examples of the groups represented by formulas (a5-r-1) to (a5-r-4) will be given below. "Ac" in a formula shows an acetyl group.

The “carbonate-containing cyclic group” refers to a cyclic group containing a ring (carbonate ring) containing —O—C (= O) —O— in the ring skeleton thereof. The carbonate ring is counted as the first ring, and in the case of only the carbonate ring, it is a monocyclic group, and when it has another ring structure, it is referred to as a polycyclic group regardless of its structure. The carbonate-containing cyclic group may be a monocyclic group or a polycyclic group.
The carbonate ring-containing cyclic group is not particularly limited, and any group can be used. Specifically, groups represented by the following general formulas (ax3-r-1) to (ax3-r-3) can be mentioned.

[ ^Wherein , each of Ra ' ^{x 31} independently represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, -COOR ", -OC (= O) R", a hydroxyalkyl group or cyano It is a group. R ′ ′ is a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or an —SO ₂ -containing cyclic group. A ′ ′ is an oxygen atom or a carbon atom that may contain a sulfur atom 1 to 5 alkylene group, oxygen atom or sulfur atom. p 'is an integer of 0 to 3, and q' is 0 or 1. ]

In the general formulas (ax3-r-2) to (ax3-r-3), A ′ ′ represents the general formulas (a2-r-2), (a2-r-3) and (a2-r-5). It is the same as A "in.
Alkyl group in ra ^'31, an alkoxy group, a halogen atom, a halogenated alkyl group, -COOR ", - OC (= O) R", The hydroxyalkyl group, each of the general formulas (a2-r-1) ~ ( a2-r-7) as in the same as those exemplified in the description of the Ra ^'21 of the like.
Specific examples of the groups represented by the general formulas (ax3-r-1) to (ax3-r-3) will be given below.

As the structural unit (a2), a structural unit derived from an acrylic acid ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted by a substituent is particularly preferable.
Specific preferred examples of the structural unit (a2) include structural units represented by general formula (a2-1) shown below.

[Wherein, R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms]. Ya ²¹ is a single bond or a divalent linking group. La ²¹ is —O—, —COO—, —CON (R ′) —, —OCO—, —CONHCO— or —CONHCS—, and R ′ is a hydrogen atom or a methyl group. However, when La ²¹ is -O-, Ya ²¹ does not become -CO-. Ra ²¹ is a lactone-containing cyclic group, a —SO ₂ -containing cyclic group or a carbonate-containing cyclic group. ]

In the formula (a2-1), R is the same as the above.
As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methyl group is particularly preferable in terms of industrial availability.

The divalent linking group of Ya ^{21 in} the formula (a2-1) is not particularly limited, but a divalent hydrocarbon group which may have a substituent and a divalent linking group containing a hetero atom Etc. are mentioned as a suitable thing.

Examples of the divalent hydrocarbon group in Ya ²¹ include the same groups as those mentioned in the description of the divalent hydrocarbon group in Va ¹ in the above-mentioned formula (a1-1). Examples of the substituent which the divalent hydrocarbon group in Ya ²¹ may have include an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogen atom, a halogenated alkyl group having 1 to 5 carbon atoms, and a hydroxyl group And carbonyl groups.

Preferable examples of the divalent linking group containing a hetero atom in Ya ²¹ include, for example, -O-, -C (= O) -O-, -C (= O)-, -O-C (= O ) -O-, -C (= O) -NH-, -NH-, -NH-C (= NH)-(H may be substituted with a substituent such as an alkyl group or an acyl group), _{-S -, - S (= O} ) 2 -, - S (= O) 2 -O-, the formula ^{^{^{-Y 21 -O-Y 22 -,}}} - Y 21 -O -, - Y 21 -C (= ^{^{O) -O -, - C (}} = O) -O-Y 21 -, - [Y 21 -C (= O) -O] m "-Y 22 -, - Y 21 -O-C (= O) A group represented by —Y ²² — or —Y ²¹ —S (= O) ₂ —O—Y ²² [in the formula, Y ²¹ and Y ²² may each independently have a substituent 2] Hydrocarbon group, O is an acid It is an atom, m "is an integer of 0 to 3. Etc.
The divalent linking group containing a hetero atom is —C (= O) —NH—, —C (= O) —NH—C (= O) —, —NH—, —NH—C (NHNH) In the case of-, the H may be substituted with a substituent such as an alkyl group or acyl. The substituent (such as an alkyl group or an acyl group) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 5 carbon atoms.
Formula ^{^{^{^{-Y 21 -O-Y 22 -,}}}} - Y 21 -O -, - Y 21 -C (= O) -O -, - C (= O) -O-Y 21 -, - [Y 21 - _{^{^{C (= O) -O] m}}} "-Y 22 -, - Y 21 -O-C (= O) -Y 22 - or ^{_{-Y 21 -S (= O) 2}} -O-Y 22 - in, Y ²¹ and Y ²² each independently represents a divalent hydrocarbon group which may have a substituent, and as the divalent hydrocarbon group, it is mentioned in the explanation as the divalent linking group. And the same groups as those described above (the bivalent hydrocarbon group which may have a substituent).
As Y ²¹ , a linear aliphatic hydrocarbon group is preferable, a linear alkylene group is more preferable, a linear alkylene group having 1 to 5 carbon atoms is further preferable, and a methylene group or an ethylene group is particularly preferable. preferable.
As Y ²² , a linear or branched aliphatic hydrocarbon group is preferable, and a methylene group, an ethylene group or an alkylmethylene group is more preferable. The alkyl group in the alkylmethylene group is preferably a linear alkyl group of 1 to 5 carbon atoms, more preferably a linear alkyl group of 1 to 3 carbon atoms, and most preferably a methyl group.
Formula ^{_{- [Y 21 -C (= O}} ) -O] m "-Y 22 - In the group represented by, m" is an integer of 0 to 3, preferably an integer of 0 to 2, 0 Or 1 is more preferable, and 1 is particularly preferable. In other words, the formula ^- Examples of the group represented by the formula ^{-Y 21 -C (= O) -O} -Y 22 - - [Y 21 -C (= O) -O] m "-Y 22 represented by group is particularly preferred among them, the formula _{_{-. (CH 2) a '}} -C (= O) -O- (CH 2) b' -. in the group represented by the formula in the formula, a 'is from 1 to It is an integer of 10, preferably an integer of 1 to 8, more preferably an integer of 1 to 5, still more preferably 1 or 2, and most preferably 1. b ′ is an integer of 1 to 10, 1 to 8 The integer of is preferable, the integer of 1 to 5 is more preferable, 1 or 2 is more preferable, and 1 is most preferable.

Ya ²¹ is preferably a single bond, an ester bond [—C (= O) —O—], an ether bond (—O—), a linear or branched alkylene group, or a combination thereof .

In the formula (a2-1), La ²¹ is —O—, —COO—, —CON (R ′) —, —OCO—, —CONHCO— or —CONHCS—.
R ′ represents a hydrogen atom or a methyl group.
However, when La ²¹ is -O-, Ya ²¹ does not become -CO-.

In the formula (a2-1), Ra ²¹ represents a lactone-containing cyclic group, a —SO ₂ -containing cyclic group or a carbonate-containing cyclic group.
The lactone-containing cyclic group, -SO ₂ -containing cyclic group, and the carbonate-containing cyclic group in Ra ²¹ are respectively represented by the general formulas (a2-r-1) to (a2-r-7) described above. Groups represented by the general formulas (a5-r-1) to (a5-r-4), and groups represented by the general formulas (ax3-r-1) to (ax3-r-3) Preferred are groups.
Among them, Ra ²¹ is preferably a lactone-containing cyclic group or a —SO ₂ -containing cyclic group, and the above general formulas (a2-r-1), (a2-r-2), (a2-r-6) or Groups represented by (a5-r-1) are more preferred. Specifically, the chemical formulas (r-lc-1-1) to (r-lc-1-7), (r-lc-2-1) to (r-lc-2-18), (r- One of the groups represented by lc-6-1), (r-sl-1-1) and (r-sl-1-18) is more preferable.

The structural unit (a2) contained in the component (A1) may be one type or two or more types.
When the component (A1) has a structural unit (a2), the proportion of the structural unit (a2) is 1 to 80 mol% relative to the total (100 mol%) of all the structural units constituting the component (A1) It is preferably 3 to 70 mol%, more preferably 5 to 60 mol%, and still more preferably 10 to 50 mol%.
The effect by containing a structural unit (a2) is fully acquired as the ratio of a structural unit (a2) is more than the lower limit of the said preferable range, and, on the other hand, is below the upper limit of the said preferable range And other structural units can be balanced, and various lithography properties and pattern shapes can be improved.

.. Constitutional unit (a3)
The component (A1) has, in addition to the structural unit (a10), the structural unit (a4) and the structural unit (a1), a structural unit (a3) containing a polar group-containing aliphatic hydrocarbon group, if necessary. (However, those which fall under any of the structural unit (a0), the structural unit (a1), and the structural unit (a2) described above are excluded).
When the component (A1) has the structural unit (a3), the hydrophilicity of the component (A) is enhanced, which contributes to the improvement of the resolution.

Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and a hydroxyalkyl group in which a part of hydrogen atoms of the alkyl group is substituted with a fluorine atom, with a hydroxyl group being particularly preferable.
The aliphatic hydrocarbon group includes a linear or branched hydrocarbon group (preferably an alkylene group) having 1 to 10 carbon atoms, and a cyclic aliphatic hydrocarbon group (cyclic group). The cyclic group may be a monocyclic group or a polycyclic group, and can be appropriately selected from among those proposed for example in a large number of resins for resist compositions for ArF excimer laser. The cyclic group is preferably a polycyclic group, and more preferably 7 to 30 carbon atoms.
Among them, a structural unit derived from an acrylic acid ester containing an aliphatic polycyclic group containing a hydroxyalkyl group in which a part of hydrogen atoms of a hydroxyl group, a cyano group, a carboxy group or an alkyl group is substituted with a fluorine atom Is more preferred. Examples of the polycyclic group include groups in which two or more hydrogen atoms have been removed from a bicycloalkane, tricycloalkane, tetracycloalkane or the like. Specific examples thereof include groups in which two or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane and tetracyclododecane. Among these polycyclic groups, groups in which two or more hydrogen atoms are removed from adamantane, groups in which two or more hydrogen atoms are removed from norbornane, and groups in which two or more hydrogen atoms are removed from tetracyclododecane are Industrially preferred.

The structural unit (a3) is not particularly limited as long as it contains a polar group-containing aliphatic hydrocarbon group, and any structural unit can be used.
The structural unit (a3) is a structural unit derived from an acrylic acid ester in which a hydrogen atom bonded to a carbon atom at the α-position may be substituted with a substituent, and a polar group-containing aliphatic hydrocarbon group Constituent units are preferred.
When the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms as the structural unit (a3), it is derived from hydroxyethyl ester of acrylic acid Structural unit is preferable, and when the hydrocarbon group is a polycyclic group, a structural unit represented by the following formula (a3-1), a structural unit represented by the formula (a3-2), a formula (a) The structural unit represented by a3-3) is preferred.

[Wherein, R is as defined above, j is an integer of 1 to 3, k is an integer of 1 to 3, t 'is an integer of 1 to 3, and l is an integer of 1 to 5] And s is an integer of 1 to 3. ]

In the formula (a3-1), j is preferably 1 or 2, and more preferably 1. When j is 2, it is preferable that the hydroxyl group be bonded to the 3rd and 5th positions of the adamantyl group. When j is 1, it is preferable that the hydroxyl group be bonded to the 3rd position of the adamantyl group.
j is preferably 1, and particularly preferably, the hydroxyl group is bonded to the 3-position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferably bonded to the 5- or 6-position of the norbornyl group.

In formula (a3-3), t ′ is preferably 1. l is preferably 1. s is preferably 1. In these, it is preferable that a 2-norbornyl group or a 3-norbornyl group is bound to the terminal of the carboxy group of acrylic acid. The fluorinated alkyl alcohol is preferably bonded to the 5 or 6 position of the norbornyl group.

The structural unit (a3) that the component (A1) has may be one type or two or more types.
When the component (A1) has the structural unit (a3), the proportion of the structural unit (a3) is 1 to 50 mol% relative to the total (100 mol%) of all the structural units constituting the component (A1) Is preferable, 3 to 40 mol% is more preferable, 5 to 30 mol% is more preferable, and 10 to 30 mol% is particularly preferable.
By setting the ratio of the structural unit (a3) to the preferable lower limit value or more, the resolution in forming a resist pattern is further enhanced. On the other hand, by setting the content to the preferable upper limit value or less, it becomes easy to balance with other constituent units.

..Constituent units derived from styrene or derivatives thereof (constituent units (st))
"Styrene" is a concept including styrene and those in which a hydrogen atom at alpha position of styrene is substituted by a substituent such as an alkyl group or a halogenated alkyl group. The alkyl group as a substituent here is an alkyl group having 1 to 5 carbon atoms, and the halogenated alkyl group as a substituent is a halogenated alkyl group having 1 to 5 carbon atoms.
As the "styrene derivative", those in which a substituent is bonded to a benzene ring of styrene which may be substituted with a hydrogen atom at the alpha position may be mentioned.
The alpha position (carbon atom at the alpha position) refers to the carbon atom to which the benzene ring is bonded unless otherwise specified.
The “structural unit derived from styrene” and the “structural unit derived from a styrene derivative” mean a structural unit formed by cleavage of an ethylenic double bond of styrene or a styrene derivative.
The structural unit (st) of the component (A1) may be of one type or of two or more types.
When the component (A1) has a structural unit (st), the proportion of the structural unit (st) is 1 to 30 mol% with respect to the total (100 mol%) of all the structural units constituting the component (A1) Is preferable, and 3 to 20 mol% is more preferable.

In the resist composition of the present embodiment, the resin component which is the component (A1) has the structural unit (a10), the structural unit (a4) and the structural unit (a1), and one type of polymer is used alone. Or two or more may be used in combination.
Preferred examples of the component (A1) include copolymers having the structural unit (a10), the structural unit (a4) and the structural unit (a1), and among these, the structural unit (a10), the structural unit (a4) and the structural unit Particularly preferred are copolymers consisting of units (a1).

The weight average molecular weight (Mw) of the component (A1) (based on polystyrene conversion by gel permeation chromatography (GPC)) is preferably 5,000 to 30,000, more preferably 6,000 to 25,000, and still more preferably 10,000 to 20,000.
It becomes easy to suppress that the viscosity of a resist composition becomes high too much that Mw of (A1) component is below the upper limit of the said preferable range. In addition, it has sufficient solubility in a resist solvent to be used as a resist, and if it is at least the lower limit value of the preferable range, a thick resist film is easily formed. In addition, the dry etching resistance and the resist pattern sectional shape become better.
The degree of dispersion (Mw / Mn) of the component (A1) is not particularly limited, and is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, and particularly preferably 1.5 to 2.5. . In addition, Mn shows a number average molecular weight.

The component (A1) includes, for example, a monomer for deriving the structural unit (a10) (a monomer in which at least a part of hydrogen atoms in hydroxyl groups bonded to a benzene ring is protected) and a monomer for deriving the structural unit (a4) A monomer for deriving the structural unit (a1) and a monomer for deriving other structural units as required are dissolved in a polymerization solvent, and, for example, azobisisobutyronitrile (AIBN), dimethyl azobisisobutyrate (for example, It can manufacture by adding and polymerizing radical polymerization initiators, such as V-601 etc., and performing a deprotection reaction after that.
In addition, at the time of polymerization, for example, by using a chain transfer agent such as HS-CH ₂ -CH ₂ -CH ₂ -C (CF ₃ ) ₂ -OH in combination, -C (CF ₃ ) at the end _{A 2-} OH group may be introduced. Thus, a copolymer in which a hydroxyalkyl group is introduced in which a part of hydrogen atoms of the alkyl group is substituted with a fluorine atom has reduced development defects and LER (line edge roughness: uneven unevenness of the line sidewall). Is effective in reducing the

As the component (A1) contained in the resist composition, one type may be used alone, or two or more types may be used in combination.
The proportion of the component (A1) in the component (A) is preferably 25% by mass or more, more preferably 50% by mass or more, further preferably 75% by mass or more, and 100% by mass, based on the total mass of the component (A). It may be When the ratio of the component (A1) is at least the lower limit value of the above-mentioned preferable range, it is excellent in high sensitivity, resolution, dimensional uniformity (CDU) in the surface of the support (Shot) and other lithography characteristics. It becomes easy to form a resist pattern of a certain shape.

The component (A) in the resist composition of this embodiment is a resin component whose solubility in a developer changes due to the action of an acid, and may contain a resin component other than the component (A1).
The content of the component (A) in the resist composition of the present embodiment may be appropriately adjusted in accordance with the thickness of the resist film to be formed.

«Other ingredients»
The resist composition of the present embodiment may further contain other components other than the component (A) in addition to the component (A) described above. Examples of the other components include the following components (B), (D), (E), (F), and (S).

Acid Generator Component (B) The resist composition of the present embodiment may further contain an acid generator component (hereinafter, referred to as “component (B)”) in addition to the component (A).
The component (B) is not particularly limited, and those which have been proposed as acid generators for chemically amplified resists can be used.
As such an acid generator, onium salt-based acid generators such as iodonium salts and sulfonium salts; oxime sulfonate-based acid generators; diazomethane-based compounds such as bisalkyl or bisarylsulfonyldiazomethanes and poly (bissulfonyl) diazomethanes Acid generators: Nitrobenzyl sulfonate-based acid generators, iminosulfonate-based acid generators, and disulfone-based acid generators. Among them, it is preferable to use an onium salt-based acid generator.

As the onium salt-based acid generator, for example, a compound represented by the following general formula (b-1) (hereinafter also referred to as “component (b-1)”), a compound represented by general formula (b-2) A compound (hereinafter also referred to as "component (b-2)") or a compound represented by general formula (b-3) (hereinafter also referred to as "component (b-3)") can be used.

[Wherein, each of R ¹⁰¹ and R ¹⁰⁴ to R ¹⁰⁸ independently has a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a substituent] It is a chain-like alkenyl group which may be R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring.
R ¹⁰² is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. Y ¹⁰¹ is a single bond or a divalent linking group containing an oxygen atom. V ¹⁰¹ to V ¹⁰³ each independently represent a single bond, an alkylene group or a fluorinated alkylene group. L ¹⁰¹ to L ¹⁰² each independently represent a single bond or an oxygen atom. L ¹⁰³ to L ¹⁰⁵ each independently represent a single bond, -CO- or -SO _2- . m is an integer of 1 or more, and M ' ^{m +} is an m-valent onium cation. ]

{Anion part}
Anion part of component (b-1) In formula (b-1), R ¹⁰¹ represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, Or a chain-like alkenyl group which may have a substituent.

Cyclic group which may have a substituent:
The cyclic group is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group means a hydrocarbon group having no aromaticity. In addition, the aliphatic hydrocarbon group may be saturated or unsaturated, and is usually preferably saturated.

The aromatic hydrocarbon group in R ¹⁰¹ is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, still more preferably 5 to 20 carbon atoms, and particularly preferably 6 to 15 carbon atoms, and 6 to 6 carbon atoms. 10 is most preferred. However, the carbon number does not include the carbon number in the substituent.
Specifically as an aromatic ring which the aromatic hydrocarbon group in R ¹⁰¹ has, benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl or a part of carbon atoms constituting these aromatic rings is substituted by a hetero atom Aromatic heterocycles and the like can be mentioned. Examples of the hetero atom in the aromatic heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom.
Specifically as the aromatic hydrocarbon group for R ^101, a group obtained by removing one hydrogen atom from the aromatic ring (aryl group: for example, phenyl group, naphthyl group etc.), one of the hydrogen atoms of the aromatic ring is an alkylene group And groups substituted by (for example, arylalkyl groups such as benzyl group, phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group, 2-naphthylethyl group and the like) and the like. The number of carbon atoms of the alkylene group (alkyl chain in the arylalkyl group) is preferably 1 to 4, more preferably 1 to 2 carbons, and particularly preferably 1 carbon.

The cyclic aliphatic hydrocarbon group in R ¹⁰¹ includes aliphatic hydrocarbon groups containing a ring in the structure.
As the aliphatic hydrocarbon group containing a ring in this structure, an alicyclic hydrocarbon group (a group obtained by removing one hydrogen atom from an aliphatic hydrocarbon ring) and an alicyclic hydrocarbon group having a linear or branched chain Examples thereof include a group bonded to the end of a linear aliphatic hydrocarbon group, and a group in which an alicyclic hydrocarbon group intervenes in the middle of a linear or branched aliphatic hydrocarbon group.
The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.
The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. As a monocyclic alicyclic hydrocarbon group, a group obtained by removing one or more hydrogen atoms from a monocycloalkane is preferable. The monocycloalkane is preferably one having 3 to 6 carbon atoms, and specific examples include cyclopentane, cyclohexane and the like. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a polycycloalkane, and as the polycycloalkane, one having 7 to 30 carbon atoms is preferable. Among them, as the polycycloalkane, a polycycloalkane having a bridged ring type polycyclic skeleton such as adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like; condensed ring systems such as cyclic groups having a steroid skeleton More preferred are polycycloalkanes having a polycyclic skeleton of

Among them, as the cyclic aliphatic hydrocarbon group for R ¹⁰¹ , a group obtained by removing one or more hydrogen atoms from a monocycloalkane or polycycloalkane is preferable, and a group obtained by removing one hydrogen atom from a polycycloalkane is more preferable. An adamantyl group and a norbornyl group are particularly preferable, and an adamantyl group is most preferable.

The linear or branched aliphatic hydrocarbon group which may be bonded to an alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, The number 1 to 4 is more preferable, and the number of carbons 1 to 3 is particularly preferable.
As a linear aliphatic hydrocarbon group, a linear alkylene group is preferable, and specifically, a methylene group [-CH _2- ], an ethylene group [-(CH ₂ ) _2- ], a trimethylene group [ _{_{- (CH 2) 3 -]}} , a tetramethylene group _{_{[- (CH 2) 4 -}} ], a pentamethylene group _{_{[- (CH 2) 5 -}} ] , and the like.
As the branched aliphatic hydrocarbon group, preferably a branched chain alkylene group, _{_{specifically, -CH (CH 3) -,}} - CH (CH 2 CH 3) -, - C (CH 3) _{_{_{_{2 -, - C (CH 3}}}} ) (CH 2 CH 3) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as - _{_{_{_{CH (CH 3) CH 2 -}}}} , - CH (CH 3) CH (CH 3) -, - C (CH 3) 2 CH 2 -, - CH (CH 2 CH 3) CH 2 -, - C (CH 2 CH ₃₎ ₂ -CH ₂ - alkyl groups such _{_{_{as; -CH (CH 3) CH 2}}} CH 2 -, - CH 2 CH (CH 3) CH 2 - alkyl trimethylene groups such as; -CH _(CH 3) _{_{_{_{CH 2 CH 2 CH 2 -,}}}} - CH 2 CH (CH 3) CH 2 CH 2 - And the like alkyl alkylene group such as an alkyl tetramethylene group of. The alkyl group in the alkyl alkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

In addition, the cyclic hydrocarbon group in R ¹⁰¹ may contain a hetero atom, such as a heterocycle. Specifically, lactone-containing cyclic groups represented by the general formulas (a2-r-1) to (a2-r-7), and the general formulas (a5-r-1) to (a5-r-) And —SO ₂ — containing cyclic groups represented by 4) and heterocyclic groups represented by the following chemical formulas (r-hr-1) to (r-hr-16).

As a substituent in the cyclic group of R ¹⁰¹ , for example, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group and the like can be mentioned.
The alkyl group as a substituent is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group or a tert-butyl group.
The alkoxy group as a substituent is preferably an alkoxy group having a carbon number of 1 to 5, and more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group or a tert-butoxy group, methoxy And ethoxy groups are most preferred.
As a halogen atom as a substituent, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, A fluorine atom is preferable.
As the halogenated alkyl group as a substituent, a part or all of hydrogen atoms such as an alkyl group having 1 to 5 carbon atoms, such as methyl group, ethyl group, propyl group, n-butyl group, tert-butyl group, etc. The group substituted by the halogen atom is mentioned.
The carbonyl group as a substituent is a group which substitutes a methylene group (—CH ₂ —) constituting a cyclic hydrocarbon group.

Chain-like alkyl group which may have a substituent:
The linear alkyl group of R ¹⁰¹ may be linear or branched.
The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbon atoms. Specifically, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decanyl group, decanyl group, undecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl Groups, pentadecyl group, hexadecyl group, isohexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group and the like.
The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10 carbon atoms. Specifically, for example, 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group, Examples include 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group and the like.

Chain-like alkenyl group which may have a substituent:
The linear alkenyl group as R ¹⁰¹ may be linear or branched, and preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, and 2 to 4 carbon atoms. More preferably, carbon number 3 is particularly preferred. As a linear alkenyl group, a vinyl group, propenyl group (allyl group), butynyl group etc. are mentioned, for example. Examples of branched alkenyl groups include 1-methylvinyl group, 2-methylvinyl group, 1-methylpropenyl group, 2-methylpropenyl group and the like.
Among the above, a linear alkenyl group is preferable, a linear alkenyl group is preferable, a vinyl group and a propenyl group are more preferable, and a vinyl group is particularly preferable.

Examples of the substituent in the chain alkyl group or alkenyl group of R ¹⁰¹ include an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, and a cyclic group in R ¹⁰¹ It can be mentioned.

Among them, R ¹⁰¹ is preferably a cyclic group which may have a substituent, and more preferably a cyclic hydrocarbon group which may have a substituent. More specifically, for example, a phenyl group, a naphthyl group, a group obtained by removing one or more hydrogen atoms from a polycycloalkane; and the above-mentioned general formulas (a2-r-1) to (a2-r-7). Preferred are lactone-containing cyclic groups to be substituted; and —SO ₂ —containing cyclic groups and the like respectively represented by the general formulas (a5-r-1) to (a5-r-4).

In formula (b-1), Y ¹⁰¹ is a single bond or a divalent linking group containing an oxygen atom.
When Y ¹⁰¹ is a divalent linking group containing an oxygen atom, the Y ¹⁰¹ may contain an atom other than the oxygen atom. As an atom other than an oxygen atom, a carbon atom, a hydrogen atom, a sulfur atom, a nitrogen atom etc. are mentioned, for example.
Examples of the divalent linking group containing an oxygen atom include an oxygen atom (ether bond: -O-), an ester bond (-C (= O) -O-), an oxycarbonyl group (-O-C (= O Non-hydrocarbons such as)-), amide bond (-C (= O) -NH-), carbonyl group (-C (= O)-), carbonate bond (-O-C (= O) -O-) etc And oxygen atom-containing linking groups of the system; combinations of such non-hydrocarbon oxygen atom-containing linking groups and alkylene groups, and the like. A sulfonyl group (—SO ₂ —) may be further linked to this combination. Examples of the divalent linking group containing such an oxygen atom include linking groups represented by the following general formulas (y-al-1) to (y-al-7).

[Wherein, V ′ ¹⁰¹ is a single bond or an alkylene group having 1 to 5 carbon atoms, and V ′ ¹⁰² is a divalent saturated hydrocarbon group having 1 to 30 carbon atoms. ]

The divalent saturated hydrocarbon group for V ′ ¹⁰² is preferably an alkylene group having 1 to 30 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms, and an alkylene group having 1 to 5 carbon atoms It is further preferred that

The alkylene group in V ′ ¹⁰¹ and V ′ ¹⁰² may be a linear alkylene group or a branched alkylene group, and a linear alkylene group is preferable.
Specifically, as an alkylene group in V ' ¹⁰¹ and V' ¹⁰² , a methylene group [-CH _2- ]; -CH (CH ₃ )-, -CH (CH ₂ CH ₃ )-, -C (CH ₃ ) _{_{_{_{2 -, - C (CH 3}}}} ) (CH 2 CH 3) -, - C (CH 3) (CH 2 CH 2 CH 3) -, - C (CH 2 CH 3) 2 - ; alkylethylene groups such as ethylene group _{_{_{_{[-CH 2 CH 2 -];}}}} - CH (CH 3) CH 2 -, - CH (CH 3) CH (CH 3) -, - C (CH 3) 2 CH 2 -, - CH (CH 2 CH ₃ ) alkyl ethylene group such as CH _2- ; trimethylene group (n-propylene group) [-CH ₂ CH ₂ CH _2- ]; -CH (CH ₃ ) CH ₂ CH _2- , -CH ₂ CH (CH ₃ ) CH ₂ - and the like alkyl trimethylene group; tetramethylene _{_{_{_{[-CH 2 CH 2 CH 2 CH}}}} 2 -]; - CH (CH 3) CH 2 CH 2 CH 2 -, - CH 2 CH (CH 3) CH 2 CH 2 - alkyl tetramethylene group and the like; pentamethylene group Examples include [-CH ₂ CH ₂ CH ₂ CH ₂ CH _2- ] and the like.
In addition, a part of methylene groups in the alkylene group in V ′ ¹⁰¹ or V ′ ¹⁰² may be substituted with a divalent aliphatic cyclic group having 5 to 10 carbon atoms. The aliphatic cyclic group is a cyclic aliphatic hydrocarbon group as R ¹⁰¹ in the formula (b-1) (monocyclic alicyclic hydrocarbon group, polycyclic alicyclic hydrocarbon group) Is preferably a divalent group from which one hydrogen atom is further removed, and more preferably a cyclohexylene group, a 1,5-adamantylene group or a 2,6-adamantylene group.

As Y ¹⁰¹ , a divalent linking group containing an ester bond or a divalent linking group containing an ether bond is preferable, and is represented by the above formulas (y-al-1) to (y-al-5) respectively. A linking group is more preferred.

In formula (b-1), V ¹⁰¹ is a single bond, an alkylene group or a fluorinated alkylene group. The alkylene group in V ¹⁰¹ and the fluorinated alkylene group preferably have 1 to 4 carbon atoms. ^Examples of the fluorinated alkylene group in V ¹⁰¹ include groups in which part or all of hydrogen atoms of the alkylene group in V ¹⁰¹ are substituted with a fluorine atom. Among them, V ¹⁰¹ is preferably a single bond or a fluorinated alkylene group having 1 to 4 carbon atoms.

In formula (b-1), R ¹⁰² is a fluorine atom or a fluorinated alkyl group of 1 to 5 carbon atoms. R ¹⁰² is preferably a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, and more preferably a fluorine atom.

(B-1) Specific examples of the anion moiety of the component, for example, if the Y ¹⁰¹ is a single bond, fluorinated alkyl sulfonate anions such as trifluoromethane sulfonate anion or perfluorobutane sulfonate anion can be exemplified; Y ¹⁰¹ is When it is a divalent linking group containing an oxygen atom, anions represented by any of the following formulas (an-1) to (an-3) can be mentioned.

[Wherein, R ′ ′ ¹⁰¹ is an aliphatic cyclic group which may have a substituent, a group represented by any of the above formulas (r-hr-1) to (r-hr-6), or a substituted group R ′ ′ ¹⁰² is an aliphatic cyclic group which may have a substituent, the above-mentioned general formula (a2-r-1) to (a2-) a lactone-containing cyclic group represented by r-7) or a —SO ₂ -containing cyclic group represented by the general formulas (a5-r-1) to (a5-r-4), respectively; R ′ ′ ¹⁰³ is an aromatic cyclic group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a chain-like alkenyl group which may have a substituent V ′ ′ is each independently an integer of 0 to 3, q ′ ′ is each independently an integer of 1 to 20, t ′ ′ is an integer of 1 to 3 and n ′ ′ is 0 The other is 1.]

The aliphatic cyclic group which may have a substituent of R ′ ′ ¹⁰¹ , R ′ ′ ¹⁰² and R ′ ′ ¹⁰³ is preferably the group exemplified as the cyclic aliphatic hydrocarbon group for R ¹⁰¹ above. Examples of the substituent include those similar to the substituents which may substitute the cyclic aliphatic hydrocarbon group for R ¹⁰¹ .

The aromatic cyclic group which may have a substituent in R ′ ¹⁰³ is preferably the group exemplified as the aromatic hydrocarbon group in the cyclic hydrocarbon group in R ¹⁰¹ described above. And the same as the substituent which may substitute the aromatic hydrocarbon group in R ¹⁰¹ .

R have a substituent in "which may chain substituted at ¹⁰¹ alkyl group, wherein preferably a group exemplified as chain alkyl group in R ¹⁰¹ .R" ¹⁰³ The chain-like alkenyl group is also preferably the group exemplified as the chain-like alkenyl group in R ¹⁰¹ above.

Anion Part of Component (b-2) In Formula (b-2), each of R ¹⁰⁴ and R ¹⁰⁵ independently has a cyclic group which may have a substituent, or a substituent. A good chained alkyl group or a chained alkenyl group which may have a substituent, each of which is similar to R ¹⁰¹ in formula (b-1). However, R ¹⁰⁴ and R ¹⁰⁵ may be bonded to each other to form a ring.
R ¹⁰⁴ and R ¹⁰⁵ each are preferably a linear alkyl group which may have a substituent, and is a linear or branched alkyl group or a linear or branched fluorinated alkyl group Is more preferred.
The carbon number of the linear alkyl group is preferably 1 to 10, more preferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbon atoms. The carbon number of the linear alkyl group of R ¹⁰⁴ and R ¹⁰⁵ is preferably as small as possible because the solubility in a resist solvent is also good within the above-mentioned range of carbon numbers. Further, in the chain alkyl group of R ¹⁰⁴ and R ^105, the greater the number of hydrogen atoms substituted by fluorine atoms, the stronger the acid strength, and the high energy light and electron beams of 200 nm or less. It is preferable because the transparency is improved.
The proportion of fluorine atoms in the linear alkyl group, ie, the fluorination ratio, is preferably 70 to 100%, more preferably 90 to 100%, and most preferably all hydrogen atoms are substituted by fluorine atoms. Perfluoroalkyl group.
In formula (b-2), each of V ¹⁰² and V ¹⁰³ independently represents a single bond, an alkylene group, or a fluorinated alkylene group, and each of them is the same as V ¹⁰¹ in formula (b-1) It can be mentioned.
In formula (b-2), L ¹⁰¹ and L ¹⁰² each independently represent a single bond or an oxygen atom.

· Anion part of component (b-3) In formula (b-3), each of R ¹⁰⁶ to R ¹⁰⁸ independently has a cyclic group which may have a substituent, or a substituent A good chained alkyl group or a chained alkenyl group which may have a substituent, each of which is the same as R ¹⁰¹ in formula (b-1).
L ¹⁰³ to L ¹⁰⁵ are each independently a single bond, -CO- or -SO _2- .

{Cation part}
In the formulas (b-1), (b-2) and (b-3), m is an integer of 1 or more, M ' ^{m +} is an m-valent onium cation, and a sulfonium cation and an iodonium cation are preferable. It can be mentioned. For example, M ′ ^{m +} is particularly preferably an organic cation represented by the following general formulas (ca-1) to (ca-5).

[Wherein, R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² each independently represent an aryl group, an alkyl group or an alkenyl group which may have a substituent, and R ²⁰¹ to R ²⁰³ and R ²⁰⁶ to R ²⁰⁷ and R ²¹¹ to R ²¹² may be mutually bonded to form a ring with the sulfur atom in the formula. R ²⁰⁸ to R ²⁰⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ²¹⁰ represents an alkyl group which may have a substituent, an alkenyl group which may have a substituent Or an -SO ₂ -containing cyclic group which may have a substituent, L ²⁰¹ represents -C (= O)-or -C (= O) -O-, and Y ²⁰¹ represents Independently, it represents an arylene group, an alkylene group or an alkenylene group, x is 1 or 2, and W ²⁰¹ represents a (x + 1) -valent linking group. ]

^Examples of the aryl group in R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² include unsubstituted aryl groups having 6 to 20 carbon atoms, and a phenyl group and a naphthyl group are preferable.
The alkyl group in R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² is preferably a linear or cyclic alkyl group having 1 to 30 carbon atoms.
The alkenyl group in R ²⁰¹ to R ²⁰⁷ and R ²¹¹ to R ²¹² preferably has 2 to 10 carbon atoms.
Examples of the substituent which R ²⁰¹ to R ²⁰⁷ and R ²¹⁰ to R ²¹² may have include an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, Groups represented by formulas (ca-r-1) to (ca-r-8) can be mentioned.

[Wherein, R ′ ²⁰¹ each independently has a hydrogen atom, a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a substituent It may be a chain-like alkenyl group. ]

The cyclic group which may have a substituent of R ′ ^201, the chain-like alkyl group which may have a substituent, or the chain-like alkenyl group which may have a substituent is And the cyclic group which may have a substituent or a chain-like alkyl group which may have a substituent, in addition to the same groups as R ¹⁰¹ in formula (b-1) The same acid dissociable group represented by formula (a1-r-2) of

When R ²⁰¹ to R ²⁰³ , R ²⁰⁶ to R ²⁰⁷ and R ²¹¹ to R ²¹² are mutually bonded to form a ring with the sulfur atom in the formula, a hetero atom such as a sulfur atom, an oxygen atom or a nitrogen atom, carbonyl _{_{group, -SO -, - SO 2 -}} , - SO 3 -, - COO -, - CONH- , or -N _(R N) - (. the _{R N} is an alkyl group having 1 to 5 carbon atoms), etc. May be bonded via a functional group of As the ring to be formed, one ring containing a sulfur atom in the formula in the ring skeleton thereof is preferably a 3- to 10-membered ring including a sulfur atom, particularly preferably a 5- to 7-membered ring. preferable. Specific examples of the ring formed include, for example, thiophene ring, thiazole ring, benzothiophene ring, thianthrene ring, benzothiophene ring, dibenzothiophene ring, 9H-thioxanthene ring, thioxanthone ring, thianthrene ring, phenoxathiin ring, tetrahydrofuran Thiophenium rings, tetrahydrothiopyranium rings and the like can be mentioned.

R ²⁰⁸ to R ²⁰⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and when it is an alkyl group, they are linked to each other It may form a ring.

R ²¹⁰ is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or a -SO ₂ -containing cyclic group which may have a substituent.
The alkyl group in R ²¹⁰ is preferably a linear or cyclic alkyl group having 1 to 30 carbon atoms.
The alkenyl group for R ²¹⁰ preferably has 2 to 10 carbon atoms.
The —SO ₂ -containing cyclic group which may have a substituent in R ²¹⁰ includes —SO ₂ represented by the general formulas (a5-r-1) to (a5-r-4) respectively. The same as the —containing cyclic group can be mentioned, and among them, “—SO ₂ -containing polycyclic group” is preferable, and a group represented by general formula (a5-r-1) is more preferable.

In formulas (ca-4) and (ca-5) above, Y ²⁰¹ each independently represents an arylene group, an alkylene group or an alkenylene group.
As the arylene group for Y ²⁰¹ , groups in which one hydrogen atom has been removed from the aryl group exemplified as the aromatic hydrocarbon group for R ¹⁰¹ in the above-mentioned formula (b-1) can be mentioned.
Examples of the alkylene group and the alkenylene group in Y ²⁰¹ include a group in which one hydrogen atom is removed from the group exemplified as the chained alkyl group and the chained alkenyl group in R ¹⁰¹ in Formula (b-1) described above. .

In the above formula (ca-4) and formula (ca-5), x is 1 or 2.
W ²⁰¹ is a (x + 1) valent, ie, a divalent or trivalent linking group.
The divalent linking group in W ²⁰¹ is preferably a divalent hydrocarbon group which may have a substituent, and has a substituent similar to Ya ²¹ in General Formula (a2-1) described above. Examples thereof include divalent hydrocarbon groups which may be substituted. The divalent linking group in W ²⁰¹ may be linear, branched or cyclic, and is preferably cyclic. Among them, a group in which two carbonyl groups are combined at both ends of an arylene group is preferable. As an arylene group, a phenylene group, a naphthylene group, etc. are mentioned, A phenylene group is especially preferable.
^Examples of the trivalent linking group in W ²⁰¹ include a group obtained by removing one hydrogen atom from the divalent linking group in W ²⁰¹ , a group in which the divalent linking group is further bonded to the divalent linking group, and the like It can be mentioned. The trivalent linking group in W ²⁰¹ is preferably a group in which two carbonyl groups are bonded to an arylene group.

Specific examples of suitable cations represented by the above formula (ca-1) include cations represented by the following formulas (ca-1-1) to (ca-1-129).

[Wherein, g1, g2 and g3 each represent a repeating number, g1 is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is an integer of 0 to 20]. ]

[Wherein, R ′ ′ ²⁰¹ is a hydrogen atom or a substituent, and the substituent is the same as the substituent mentioned above as the substituent that R ²⁰¹ to R ²⁰⁷ and R ²¹⁰ to R ²¹² may have. It is

Specific examples of suitable cations represented by the above formula (ca-2) include diphenyliodonium cation and bis (4-tert-butylphenyl) iodonium cation.

Specific examples of suitable cations represented by the above formula (ca-3) include cations represented by the following formulas (ca-3-1) to (ca-3-5).

Specific examples of suitable cations represented by the above formula (ca-4) include cations represented by the following formulas (ca-4-1) to (ca-4-2).

Further, as the cation represented by the formula (ca-5), cations represented by the following general formulas (ca-5-1) to (ca-5-3) are also preferable.

Among the above, the cation part [(M ′ ^{m +} ) _{1 / m 2} ] is preferably a cation represented by the general formula (ca-1), more preferably a monophenyl type cation.
Furthermore, as a preferable cation part [(M ′ ^{m +} ) _{1 / m 2} ], a monophenyl type cation represented by the following general formula (ca-1-0) can be mentioned.

[Wherein, R ^b1 is an aryl group which may have a substituent. R ^b2 and R ^b3 are each independently an aliphatic hydrocarbon group. R ^b2 and R ^b3 may be bonded to each other to form a ring structure. L ^b1 , L ^b2 and L ^b3 are each independently a divalent linking group or a single bond. ]

In the above formula (ca-1-0), R ^b1 is an aryl group which may have a substituent, and is the same as the aryl group which may have a substituent in R ²⁰¹ to R ²⁰³ . That is, examples of the aryl group in R ^b1 include aryl groups having 6 to 20 carbon atoms, and a phenyl group and a naphthyl group are preferable. Examples of the substituent which R ^b1 may have include an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, the above-mentioned formulas (ca-r-1) to groups represented by ca-r-8) can be mentioned.

In formula (ca-1-0), R ^b2 and R ^b3 are each independently an aliphatic hydrocarbon group. The aliphatic hydrocarbon group in R ^b2 and R ^b3 may be linear or cyclic, and may be a linear or cyclic alkyl group or alkenyl group.
The chain or cyclic alkyl group here is preferably one having 1 to 30 carbon atoms.
The alkenyl group here preferably has 2 to 10 carbon atoms.

R ^b2 and R ^b3 may be bonded to each other to form a ring structure. When they are combined to form a ring with a sulfur atom in the formula, a hetero atom such as a sulfur atom, an oxygen atom or a nitrogen atom, a carbonyl group, -SO-, -SO _2- , -SO ₃ -or -COO They may be bonded via a functional group such as —, —CONH— or —N (R _N ) — (wherein R _N is an alkyl group of 1 to 5 carbon atoms). As the ring to be formed, one ring containing a sulfur atom in the formula in the ring skeleton thereof is preferably a 3- to 10-membered ring including a sulfur atom, particularly preferably a 5- to 7-membered ring. preferable. Specific examples of the ring formed include, for example, thiophene ring, thiazole ring, benzothiophene ring, thianthrene ring, benzothiophene ring, dibenzothiophene ring, 9H-thioxanthene ring, thioxanthone ring, thianthrene ring, phenoxathiin ring, tetrahydrofuran Thiophenium rings, tetrahydrothiopyranium rings and the like can be mentioned.

In the formula (ca-1-0), L ^b1 , L ^b2 and L ^b3 are each independently a divalent linking group or a single bond.
As a bivalent coupling group in L ^b1 , L ^b2 and L ^b3 , each independently —C (= O) —, —C (= O) —O—, —O—C (= O) —, arylene And alkylene groups and alkenylene groups.

The arylene group in L ^b1 , L ^b2 and L ^b3 is a group in which one hydrogen atom is further removed from the aryl group exemplified as the aromatic hydrocarbon group in R ¹⁰¹ in the above-mentioned formula (b-1). That is, two hydrogen atoms are removed from an aromatic ring (benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, or an aromatic heterocyclic ring in which part of carbon atoms constituting the aromatic ring is substituted with a hetero atom, etc.) Group is mentioned.
The alkylene group or alkenylene group in L ^b1 , L ^b2 and L ^b3 is a hydrogen atom selected from the groups exemplified as the chain alkyl group and chain alkenyl group in R ¹⁰¹ in the above-mentioned formula (b-1) And the other groups are mentioned. That is, a group in which one hydrogen atom is further removed from a linear alkyl group having 1 to 20 carbon atoms, and a group in which one hydrogen atom is removed from a branched alkyl group having 3 to 20 carbon atoms is It can be mentioned.

L ^b1 is preferably a single bond because the acid generation efficiency ^upon exposure is further enhanced.

More preferable examples of the cation part of the component (B) include a cation represented by the following general formula (ca-1-01) or a cation represented by the general formula (ca-1-02). Particularly preferred is a cation represented by general formula (ca-1-01).

[ ^Wherein , R ^b11 and R ^b12 are each independently an aryl group which may have a substituent. L ^b11 is —C (= O) — or —C (= O) —O—. R ^b121 and R ^b122 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. nb1 is an integer of 1 to 3. nb2 is an integer of 1 to 3. ]

In the above formulae, R ^b11 and R ^b12 are each the same as R ^b1 in the above formula (ca-1-0). Among them, preferred is an unsubstituted aryl group. Preferred aryl groups include phenyl and naphthyl groups.
R ^b121 and R ^b122 each is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom, a methyl group or an ethyl group, and more preferably a hydrogen atom.
nb1 is an integer of 1 to 3, preferably 1 or 2, and more preferably 2.
nb2 is an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

As the cation represented by the general formula (ca-1-01), the cations respectively represented by the chemical formulas (ca-1-104) to (ca-1-129) described above are preferable, and among these, the chemical formula The cation represented by ca-1-104) and the cation represented by the chemical formula (ca-1-105) (R ′ ²⁰¹ is a hydrogen atom) are more preferable.
As the cation represented by the general formula (ca-1-02), the cation represented by the above chemical formula (ca-1-102) and the cation represented by the chemical formula (ca-1-103) are preferable.

As the component (B), one type of acid generator described above may be used alone, or two or more types may be used in combination.
As the component (B) in the present embodiment, a compound represented by the following general formula (b-1-0) is particularly preferable.

^Wherein, R ^{^101,} Y ^101, ^V ¹⁰¹ and ^{R 102} are each similar to ^R ^{^101,} Y ^101, ^V 101 and ^{R 102} in the formula (b-1). R ^b11 and nb 1 are respectively the same as R ^b11 and nb 1 in the formula (ca-1-01). ]

When the resist composition contains component (B), the content of component (B) is preferably 0.5 to 7 parts by mass, and more preferably 1 to 4 parts by mass with respect to 100 parts by mass of component (A). And 1 to 3 parts by mass is more preferable.
By setting the content of the component (B) in the above range, pattern formation is sufficiently performed. Moreover, when each component of the resist composition is dissolved in an organic solvent, a uniform solution is easily obtained, and the storage stability as the resist composition becomes good, which is preferable. Moreover, by making content of (B) component more than the lower limit of the said preferable range, the light transmittance of a resist film becomes easy to be improved, and high sensitivity-ization is easy to be achieved.

Acid Diffusion Control Agent Component (D) The resist composition of the present embodiment may further contain an acid diffusion control agent component (A) in addition to the component (A) or in addition to the components (A) and (B). You may contain "the (D) component." The component (D) acts as a quencher (acid diffusion control agent) which traps an acid generated by exposure in the resist composition.
The component (D) may be a photodisintegrable base (D1) (hereinafter referred to as “component (D1)”) which is decomposed by exposure to lose acid diffusion controllability, and does not fall under the component (D1). It may be a nitrogen organic compound (D2) (hereinafter referred to as "component (D2)").

Component (D1) Component By using the resist composition containing the component (D1), when the resist pattern is formed, the contrast between the exposed portion and the unexposed portion of the resist film can be improved.
The component (D1) is not particularly limited as long as it decomposes upon exposure and loses acid diffusion controllability, and a compound represented by the following general formula (d1-1) (hereinafter referred to as “component (d1-1) component” It is said.
A compound represented by the following general formula (d1-2) (hereinafter referred to as "(d1-2) component") and a compound represented by the following general formula (d1-3) (hereinafter referred to as "(d1-3) Component (1) is preferably one or more compounds selected from the group consisting of
The components (d1-1) to (d1-3) do not act as a quencher because they are decomposed in the exposed portion of the resist film to lose acid diffusion controllability (basicity), but act as a quencher in the unexposed portion. Do.

[Wherein, Rd ¹ to Rd ⁴ each represents a cyclic group which may have a substituent, a chain alkyl group which may have a substituent, or a chain which may have a substituent] Alkenyl group of However, it is assumed that a fluorine atom is not bonded to the carbon atom adjacent to the S atom in Rd ² in the formula (d1-2). Yd ¹ is a single bond or a divalent linking group. m is an integer of 1 or more, and M ^{m +} is independently an m-valent organic cation. ]

{(D1-1) ingredients}
... Anion part In formula (d1-1), Rd ¹ has a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a substituent And an optionally substituted chain-like alkenyl group, each of which is the same as R ¹⁰¹ in the formula (b-1).
Among these, Rd ¹ may have an aromatic hydrocarbon group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a substituent. A linear alkyl group is preferred. Examples of the substituent which these groups may have include a hydroxyl group, an oxo group, an alkyl group, an aryl group, a fluorine atom, a fluorinated alkyl group, and the general formulas (a2-r-1) to (a2-r-). The lactone containing cyclic group respectively represented by 7), ether bond, ester bond, or these combination is mentioned. When an ether bond or an ester bond is contained as a substituent, it may be via an alkylene group, and the substituent in this case is represented by the above formulas (y-al-1) to (y-al-5) A linking group is preferred.
The aromatic hydrocarbon group is more preferably a phenyl group or a naphthyl group.
The aliphatic cyclic group is more preferably a group in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane or tetracyclododecane.
The chain alkyl group preferably has 1 to 10 carbon atoms, and specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, Linear alkyl group such as nonyl group and decyl group; 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylbutyl group And branched alkyl groups such as 2-ethylbutyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group and 4-methylpentyl group.

When the chain alkyl group is a fluorinated alkyl group having a fluorine atom or a fluorinated alkyl group as a substituent, the carbon number of the fluorinated alkyl group is preferably 1 to 11, and more preferably 1 to 8 carbon atoms And more preferably 1 to 4 carbon atoms. The fluorinated alkyl group may contain an atom other than a fluorine atom. As an atom other than a fluorine atom, an oxygen atom, a sulfur atom, a nitrogen atom etc. are mentioned, for example.
Rd ¹ is preferably a fluorinated alkyl group in which a part or all of the hydrogen atoms constituting the linear alkyl group are substituted by a fluorine atom, and one of the hydrogen atoms constituting the linear alkyl group is preferred. Particularly preferred is a fluorinated alkyl group (a linear perfluoroalkyl group) which is all substituted with a fluorine atom.

Preferred specific examples of the anion moiety of the component (d1-1) are shown below.

In the formula (d1-1), M ^{m +} is an m-valent organic cation.
Preferred examples of the organic cation of M ^{m +} include the same as the cations respectively represented by the general formulas (ca-1) to (ca-5), and the organic cation is represented by the general formula (ca-1) The cation is more preferable, and the cation represented by each of the above formulas (ca-1-1) to (ca-1-129) is more preferable.
As the component (d1-1), one type may be used alone, or two or more types may be used in combination.

{(D1-2) ingredients}
... Anion part In formula (d1-2), Rd ² has a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a substituent. A chained alkenyl group which may be substituted, and examples thereof include the same ones as R ¹⁰¹ in the formula (b-1).
However, a fluorine atom is not bonded to the carbon atom adjacent to the S atom in Rd ² (not substituted with fluorine). Thereby, the anion of the component (d1-2) becomes a moderate weak acid anion, and the quenching ability as the component (D) is improved.
Rd ² is preferably a chain-like alkyl group which may have a substituent or an aliphatic cyclic group which may have a substituent. The chain alkyl group preferably has 1 to 10 carbon atoms, and more preferably 3 to 10 carbon atoms. As an aliphatic cyclic group, a group obtained by removing one or more hydrogen atoms from adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane or the like (which may have a substituent); 1 from camphor etc. It is more preferable that it is the group except the above hydrogen atom.
The hydrocarbon group of Rd ² may have a substituent, and examples of the substituent include a hydrocarbon group (aromatic hydrocarbon group, aliphatic cyclic group, and the like in Rd ¹ of the formula (d1-1). The same substituents as those which the chain alkyl group may have may be mentioned.

Preferred specific examples of the anion moiety of the component (d1-2) are shown below.

In the formula (d1-2), M ^{m +} is an m-valent organic cation, and is the same as M ^{m +} in the formula (d1-1).
As the component (d1-2), one type may be used alone, or two or more types may be used in combination.

{(D1-3) ingredients}
... Anion part In formula (d1-3), Rd ³ has a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a substituent An optionally substituted chain-like alkenyl group, including the same as R ¹⁰¹ in the formula (b-1), and a cyclic group containing a fluorine atom, a chain-like alkyl group, or a chain-like alkenyl It is preferably a group. Among them, a fluorinated alkyl group is preferable, and the same fluorinated alkyl group as Rd ¹ is more preferable.

In the formula (d1-3), Rd ⁴ may have a cyclic group which may have a substituent, a linear alkyl group which may have a substituent, or a substituent. It is a chain alkenyl group, and examples thereof include the same ones as R ¹⁰¹ in the formula (b-1).
Among them, an alkyl group which may have a substituent, an alkoxy group, an alkenyl group and a cyclic group are preferable.
The alkyl group in Rd ⁴ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group And tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. A part of the hydrogen atoms of the alkyl group of Rd ⁴ may be substituted with a hydroxyl group, a cyano group or the like.
The alkoxy group in Rd ⁴ is preferably an alkoxy group having a carbon number of 1 to 5, and specific examples of the alkoxy group having a carbon number of 1 to 5 include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, and n- Examples include butoxy and tert-butoxy. Among these, methoxy and ethoxy are preferable.

The alkenyl group in Rd ⁴ includes the same as R ¹⁰¹ in the above formula (b-1), and a vinyl group, propenyl group (allyl group), 1-methylpropenyl group and 2-methylpropenyl group are preferable. These groups may further have an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms as a substituent.

The cyclic group in Rd ⁴ includes the same as R ¹⁰¹ in the above formula (b-1), and cycloalkanes such as cyclopentane, cyclohexane, adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane and the like An alicyclic group from which one or more hydrogen atoms have been removed, or an aromatic group such as a phenyl group or a naphthyl group is preferred. When Rd ⁴ is an alicyclic group, the resist composition is well dissolved in the organic solvent, whereby the lithography properties are improved. In addition, when Rd ⁴ is an aromatic group, the resist composition is excellent in light absorption efficiency, and sensitivity and lithography properties become good.

In formula (d1-3), Yd ¹ represents a single bond or a divalent linking group.
The divalent linking group in Y d ¹ is not particularly limited, and may be a divalent hydrocarbon group (aliphatic hydrocarbon group, aromatic hydrocarbon group) which may have a substituent, a hetero atom And the like. These respectively contain the bivalent hydrocarbon group which may have a substituent, and hetero atom which were mentioned in the description about the bivalent coupling group in Ya ²¹ in the said Formula (a2-1). The same thing as a bivalent coupling group is mentioned.
As Yd ¹ , a carbonyl group, an ester bond, an amide bond, an alkylene group or a combination thereof is preferable. The alkylene group is more preferably a linear or branched alkylene group, and still more preferably a methylene group or an ethylene group.

Preferred specific examples of the anion moiety of the (d1-3) component are shown below.

In the formula (d1-3), M ^{m +} is an m-valent organic cation, and is the same as M ^{m +} in the formula (d1-1).
As the component (d1-3), one type may be used alone, or two or more types may be used in combination.

As the component (D1), any one of the components (d1-1) to (d1-3) may be used alone, or two or more kinds of the components may be used in combination.
When the resist composition contains the component (D1), the content of the component (D1) is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the component (A). The amount is more preferably 8 parts by mass, further preferably 1 to 8 parts by mass.
When the content of the component (D1) is equal to or more than the preferable lower limit value, particularly favorable lithography characteristics and a resist pattern shape are easily obtained. On the other hand, when it is below the upper limit value, the sensitivity can be favorably maintained and the throughput is also excellent.

Method of producing the component (D1):
The method for producing the components (d1-1) and (d1-2) is not particularly limited, and the components can be produced by known methods.
Further, the method for producing the component (d1-3) is not particularly limited, and the component (d1-3) is produced, for example, in the same manner as the method described in US2012-0149916.

-About a component (D2) As an acid diffusion controlling agent component, you may contain the nitrogen-containing organic compound component (henceforth "the (D2) component") which does not correspond to said (D1) component.
The component (D2) functions as an acid diffusion control agent and is not particularly limited as long as it does not correspond to the component (D1), and any known one may be used. Among them, aliphatic amines are preferable, and in particular, secondary aliphatic amines and tertiary aliphatic amines are more preferable.
The aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic group preferably has 1 to 12 carbon atoms.
Examples of aliphatic amines include amines in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms (alkylamine or alkylalcoholamine) or cyclic amine.
Specific examples of the alkylamine and the alkyl alcoholamine include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine and n-decylamine; diethylamine, di-n-propylamine, di-amine -Dialkylamines such as n-heptylamine, di-n-octylamine and dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine , Trialkylamines such as tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, tri-n-dodecylamine, etc .; diethanolamine, triethanolamine, diisopropanolamine, Li isopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, trialkylamines of 5 to 10 carbon atoms are more preferable, and tri-n-pentylamine or tri-n-octylamine is particularly preferable.

The cyclic amine includes, for example, a heterocyclic compound containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of aliphatic monocyclic amines include piperidine, piperazine and the like.
The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, and specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-Undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane and the like.

Other aliphatic amines include tris (2-methoxymethoxyethyl) amine, tris {2- (2-methoxyethoxy) ethyl} amine, tris {2- (2-methoxyethoxymethoxy) ethyl} amine, tris {2 -(1-methoxyethoxy) ethyl} amine, tris {2- (1-ethoxyethoxy) ethyl} amine, tris {2- (1-ethoxypropoxy) ethyl} amine, tris [2- {2- (2-hydroxy) Ethoxy) ethoxy} ethyl] amine, triethanolamine triacetate, etc. are mentioned, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.
As the aromatic amine, 4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole or derivatives thereof, tribenzylamine, 2,6-diisopropylaniline, N-tert-butoxycarbonylpyrrolidine and the like can be mentioned.

The component (D2) may be used alone or in combination of two or more.
When the resist composition contains the component (D2), the component (D2) is used usually in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the component (A). By setting it in the above-mentioned range, the resist pattern shape, the stability over time of placing, etc. are improved.

· At least one compound (E) selected from the group consisting of organic carboxylic acids and phosphorus oxo acids and derivatives thereof The resist composition of this embodiment can be used to prevent sensitivity deterioration, resist pattern shape, For the purpose of improving the stability over time, etc., at least one compound (E) (hereinafter referred to as “component (E)” selected from the group consisting of organic carboxylic acids and phosphorus oxo acids and their derivatives as optional components. Can be contained.
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are preferable.
Examples of phosphorus oxo acids include phosphoric acid, phosphonic acid and phosphinic acid. Among these, phosphonic acid is particularly preferable.
Examples of derivatives of oxo acids of phosphorus include esters in which a hydrogen atom of the above oxo acid is substituted with a hydrocarbon group, and examples of the hydrocarbon group include an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like can be mentioned.
Examples of derivatives of phosphoric acid include phosphoric acid di-n-butyl ester, phosphoric acid esters such as phosphoric acid diphenyl ester, and the like.
Examples of derivatives of phosphonic acid include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of phosphinic acid derivatives include phosphinic acid esters and phenylphosphinic acid.
As the component (E), one type may be used alone, or two or more types may be used in combination.
When the resist composition contains the component (E), the component (E) is used usually in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the component (A).

-About a fluorine additive component (F) The resist composition of this embodiment may contain a fluorine additive component (henceforth "(F) component"), in order to provide water repellency to a resist film. .
As the component (F), for example, those described in JP-A-2010-002870, JP-A-2010-032994, JP-A-2010-277043, JP-A-2011-13569, and JP-A-2011-128226. The fluorine-containing polymer compound of can be used.
More specific examples of the component (F) include polymers having a structural unit (f1) represented by the following formula (f1-1). As the polymer, a polymer (homopolymer) consisting only of a structural unit (f1) represented by the following formula (f1-1); a structural unit (a1) containing an acid degradable group whose polarity is increased by the action of an acid The copolymer of the structural unit (f1), the structural unit derived from acrylic acid or methacrylic acid, and the structural unit (a1) is preferable. Here, preferable examples of the structural unit (a1) to be copolymerized with the structural unit (f1) include, for example, a structural unit derived from 1-ethyl-1-cyclooctyl (meth) acrylate, 1-methyl And -1-adamantyl (meth) acrylate-derived constitutional units.

[Wherein, R is as defined above, and Rf ¹⁰² and Rf ¹⁰³ each independently represent a hydrogen atom, a halogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms, Rf ¹⁰² and Rf ¹⁰³ may be the same or different. nf ¹ is an integer of 1 to 5, and Rf ¹⁰¹ is an organic group containing a fluorine atom. ]

In the formula (f1-1), R bonded to the carbon atom at the α-position is as defined above. As R, a hydrogen atom or a methyl group is preferable.
In the formula (f1-1), as the halogen atom of Rf ¹⁰² and Rf ¹⁰³ , a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like can be mentioned, with a fluorine atom being particularly preferable. Examples of the alkyl group having 1 to 5 carbon atoms of Rf ¹⁰² and Rf ¹⁰³ include the same as the alkyl group having 1 to 5 carbon atoms of R described above, and a methyl group or an ethyl group is preferable. Specific examples of the halogenated alkyl group having 1 to 5 carbon atoms of Rf ¹⁰² and Rf ¹⁰³ include groups in which part or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are substituted with a halogen atom. Be
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is particularly preferable. Among them, a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms is preferable as Rf ¹⁰² and Rf ¹⁰³ , and a hydrogen atom, a fluorine atom, a methyl group or an ethyl group is preferable.
In the formula (f1-1), nf ¹ is an integer of 1 to 5, preferably an integer of 1 to 3, and more preferably 1 or 2.

In the formula (f1-1), Rf ¹⁰¹ is an organic group containing a fluorine atom, and is preferably a hydrocarbon group containing a fluorine atom.
The hydrocarbon group containing a fluorine atom may be linear, branched or cyclic, and preferably has 1 to 20 carbon atoms, and more preferably 1 to 15 carbon atoms. And 1 to 10 carbon atoms are particularly preferable.
Moreover, as for the hydrocarbon group containing a fluorine atom, it is preferable that 25% or more of the hydrogen atoms in the said hydrocarbon group are fluorinated, It is more preferable that 50% or more is fluorinated, 60% or more Fluorination is particularly preferable because the hydrophobicity of the resist film at the time of immersion exposure is increased.
Among them, Rf ¹⁰¹ is more preferably a fluorinated hydrocarbon group having a carbon number of 1 to 6, and a trifluoromethyl group, -CH ₂ -CF ₃ , -CH ₂ -CF ₂ -CF ₃ , -CH (CF ₃ ₂ ), -CH ₂ -CH ₂ -CF ₃ , -CH ₂ -CH ₂ -CF ₂ -CF ₂ -CF ₂ -CF ₃ are particularly preferred.

The weight average molecular weight (Mw) of the component (F) (based on polystyrene conversion by gel permeation chromatography) is preferably 1000 to 50000, more preferably 5000 to 40000, and most preferably 10000 to 30000. When it is below the upper limit of this range, it has sufficient solubility in a resist solvent to be used as a resist, and when it is above the lower limit of this range, the dry etching resistance and the resist pattern cross-sectional shape are good.
The dispersion degree (Mw / Mn) of the component (F) is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

As the component (F), one type may be used alone, or two or more types may be used in combination.
When the resist composition contains the component (F), the component (F) is used usually in a proportion of 0.5 to 10 parts by mass with respect to 100 parts by mass of the component (A).

Organic Solvent Component (S) The resist composition of the present embodiment can be produced by dissolving a resist material in an organic solvent component (hereinafter sometimes referred to as “(S) component”).
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution, and any component can be appropriately selected from conventionally known solvents for chemically amplified resist compositions. It can be selected and used.
For example, as component (S), lactones such as γ-butyrolactone; acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, ketones such as 2-heptanone, ethylene glycol, diethylene glycol, propylene glycol, Polyhydric alcohols such as dipropylene glycol; compounds having an ester bond such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, or dipropylene glycol monoacetate, the above polyhydric alcohols or compounds having the ester bond Monoalkyl ethers such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether, etc. or monophenyl ether Derivatives of polyhydric alcohols such as compounds having an ether bond (eg, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred among them); cyclic ethers such as dioxane And esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypropionate; anisole, ethyl benzyl ether, cresyl Methylether, diphenylether, dibenzylether, phenetole, butylphenylether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene And aromatic organic solvents such as dimethyl carbonate, dimethyl sulfoxide (DMSO) and the like.
The component (S) may be used alone or as a mixed solvent of two or more.
Among them, PGMEA, PGME, γ-butyrolactone, EL and cyclohexanone are preferable.

Moreover, the mixed solvent which mixed PGMEA and the polar solvent is also preferable. The compounding ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, etc., but is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. It is preferable to be in the range.
More specifically, when blending EL or cyclohexanone as a polar solvent, the weight ratio of PGMEA: EL or cyclohexanone is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. . When PGME is blended as a polar solvent, the mass ratio of PGMEA: PGME is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2, further preferably 3: 7 to 7: It is three. Furthermore, mixed solvents of PGMEA, PGME and cyclohexanone are also preferable.
In addition, as the component (S), a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, as the mixing ratio, the mass ratio of the former to the latter is preferably 70:30 to 95: 5.

The amount of the component (S) to be used is not particularly limited, and is a concentration that can be applied to a substrate or the like, and is appropriately set according to the applied film thickness. In general, the (S) component is used so that the solid content concentration of the resist composition is in the range of 20 to 55% by mass, preferably 30 to 45% by mass.

In the resist composition of the present embodiment, additives which are optionally miscible, for example, an additional resin for improving the performance of the resist film, a surfactant (for example, a fluorine-based surfactant etc.), a solution An inhibitor, a plasticizer, a stabilizer, a coloring agent, an antihalation agent, a dye and the like can be appropriately added and contained.

The method for forming a resist pattern according to this aspect described above is a method useful for forming a thick resist film having a thickness of 7 μm or more, and is performed using a specific resist composition.
By using a specific resist composition, that is, a resist composition containing a resin component (A1) having the structural unit (a10), the structural unit (a4) and the structural unit (a1), a resist film having a large thickness can be obtained. Light transmission is enhanced. Thus, even when forming a thick resist film having a thickness of 7 μm or more, high sensitivity can be achieved and resolution can be improved, and a resist pattern having a good shape can be formed. .

In addition, according to such a resist pattern forming method, the solubility in a developer is improved by using the above-mentioned specific resist composition. This makes it possible to suppress the occurrence of defects and to improve the stability of pattern dimensions. Furthermore, according to such a resist pattern forming method, sufficient etching resistance is maintained.

Such a resist pattern forming method is useful for manufacturing a three-dimensional structure device, and is a method suitable for applications (such as superposition) in which a multi-step structure is processed. By applying the resist pattern forming method of the present embodiment, it is possible to realize the lamination (three-dimensionalization, manufacture of a large capacity memory) of the memory film with high accuracy.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

<Preparation of Resist Composition>
Each component shown in Table 1 was mixed and dissolved to prepare resist compositions (1) to (6) (all have a solid content concentration of 40% by mass).

Each abbreviation in Table 1 has the following meaning. The numerical values in [] are compounding amounts (parts by mass).
(A) -1: a polymer compound represented by the following chemical formula (A1) -1. The weight average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement is 10000, and molecular weight dispersion degree (Mw / Mn) is 2.5. ^The copolymerization compositional ratio (the ratio (molar ratio) of each structural unit in the structural formula) determined by ¹³ C-NMR is as follows: structural unit (a101) / structural unit (a41) / structural unit (a11) = 50/35 / 15.

(A) -2: a polymer compound represented by the following chemical formula (A1) -1. The weight average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement is 10000, and molecular weight dispersion degree (Mw / Mn) is 2.5. ^The copolymerization composition ratio (the ratio (molar ratio) of each structural unit in the structural formula) determined by ¹³ C-NMR is as follows: structural unit (a101) / structural unit (a41) / structural unit (a11) = 65/20 / 15.

(A) -3: a polymer compound represented by the following chemical formula (A1) -1. The weight average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement is 10000, and molecular weight dispersion degree (Mw / Mn) is 2.5. ^The copolymerization compositional ratio (the ratio (molar ratio) of each structural unit in the structural formula) determined by ¹³ C-NMR is as follows: structural unit (a101) / structural unit (a41) / structural unit (a11) = 70/15 / 15.

(A) -4: a polymer compound represented by the following chemical formula (A1) -1. The weight average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement is 10000, and molecular weight dispersion degree (Mw / Mn) is 2.5. ^The copolymerization compositional ratio (the ratio (molar ratio) of each structural unit in the structural formula) determined by ¹³ C-NMR is as follows: structural unit (a101) / structural unit (a41) / structural unit (a11) = 40/45 / 15.

(A) -5: a polymer compound represented by the following chemical formula (A1) -1. The weight average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement is 10000, and molecular weight dispersion degree (Mw / Mn) is 2.5. ^The copolymerization composition ratio (the ratio (molar ratio) of each structural unit in the structural formula) determined by ¹³ C-NMR is as follows: structural unit (a 101) / structural unit (a 41) / structural unit (a 11) = 80/5 / 15.

(A) -6: a polymer compound represented by the following chemical formula (A2) -1. The weight average molecular weight (Mw) of standard polystyrene conversion calculated | required by GPC measurement is 10000, and molecular weight dispersion degree (Mw / Mn) is 2.5. ^The copolymerization composition ratio (the ratio (molar ratio) of each structural unit in the structural formula) determined by ¹³ C-NMR is as follows: structural unit (a101) / structural unit (st1) / structural unit (a12) = 65/20 / 15.

(B) -1: An acid generator comprising a compound represented by the following chemical formula (B) -1.

(D) -1: tri-n-pentylamine.
(E) -1: phenylphosphonic acid.
(Add) -1: Fluorosurfactant, trade name "R-40" manufactured by DIC Corporation.
(S) -1: propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 5/5 (mass ratio).

<Formation of resist pattern (I)>
(Examples 1 to 3)
Process (i):
Apply resist compositions (1) to (3) on an 8-inch silicon wafer using a coater, respectively, perform pre-baking (PAB) treatment at 130 ° C. for 90 seconds on a hot plate, and dry it. Thus, a resist film with a film thickness of 15 μm was formed.
Process (ii):
Next, a KrF excimer laser (248 nm) was mask pattern (6%) to the resist film by a KrF exposure apparatus NSR-S203B (manufactured by Nikon; NA (numerical aperture) = 0.68, .sigma. = 0.40). Selectively irradiated through the halftone).
Then, post exposure bake (PEB) processing was performed at 110 ° C. for 90 seconds.
Step (iii):
Next, using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution “NMD-3” (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) as a developer, alkaline development was performed under conditions of 23 ° C. for 60 seconds. The
Thereafter, using pure water, water rinse was performed for 30 seconds, and shake-off and drying were performed.

(Comparative example 1)
A resist pattern was formed in the same manner as in Examples 1 to 3 except that the resist composition (6) was used.

As a result of the formation (I) of the resist pattern described above, in any of the examples, a pattern of isolated lines with a space width of 5 μm (hereinafter referred to as “IS pattern”) was formed in the resist film.

[sensitivity]
The optimum exposure Eop (mJ / cm ² ) was determined as the sensitivity when the IS pattern of the target size was formed by the formation of the resist pattern (I) described above. This is shown in Table 2 as "Eop (mJ / cm ² )".

[Shape of resist pattern]
The shape of the IS pattern formed by the formation of the resist pattern (I) described above was observed with a length measurement SEM (scanning electron microscope, accelerating voltage 800 V, trade name: SU-8000, manufactured by Hitachi High-Technologies Corporation) The evaluation results are shown in Table 2 as “shape” according to the evaluation criteria of
Evaluation criteria A: Tapered shape B: Top-round shape

From the results shown in Table 2, according to the resist pattern forming methods of Examples 1 to 3, even when forming a resist film having a film thickness of 15 μm, it shows high sensitivity and a good shape. It is recognized that patterns can be formed.
On the other hand, in the resist pattern forming method of Comparative Example 1, the sensitivity was low and the shape was also poor.

<Formation of resist pattern (II)>
(Examples 4 to 8)
Process (i):
Apply resist compositions (1) to (5) on an 8-inch silicon wafer using a coater, respectively, and perform prebaking (PAB) treatment at 130 ° C. for 90 seconds on a hot plate and dry it. Thus, a resist film with a film thickness of 15 μm was formed.
Process (ii):
Next, a KrF excimer laser (248 nm) was mask pattern (6%) to the resist film by a KrF exposure apparatus NSR-S203B (manufactured by Nikon; NA (numerical aperture) = 0.68, .sigma. = 0.40). Selectively irradiated through the halftone).
Then, post exposure bake (PEB) processing was performed at 110 ° C. for 90 seconds.
Step (iii):
Next, using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution “NMD-3” (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) as a developer, alkaline development was performed under conditions of 23 ° C. for 60 seconds. The
Thereafter, using pure water, water rinse was performed for 30 seconds, and shake-off and drying were performed.

As a result of the formation (II) of the resist pattern described above, in any of the examples, a pattern of an isolated line with a space width of 3 μm (hereinafter referred to as “IS pattern”) was formed in the resist film.

[Defect (number of defects)]
With respect to the IS pattern formed by the formation (II) of the resist pattern described above, the total number of defects in the wafer (the total number of defects) was measured using a surface defect observation apparatus (product name: KLA 2371 manufactured by KLA Tencor Co., Ltd.).
The number of wafers used for this measurement was two for each example, and the total number of defects in the wafer (the total number of defects) was the average value. And according to the following evaluation criteria, the evaluation result was shown in Table 3 as "Defect".
Evaluation criteria A: The number of defects is 200 or less B: The number of defects is more than 200 and less than 300 C: The number of defects is 300 or more

[Dimensional uniformity (CDU) in wafer surface (Shot)]
The IS pattern (scanning electron microscope, accelerating voltage 300 V, trade name: S-9380, manufactured by Hitachi High-Technologies Corporation) was used as the IS pattern (IS) formed by forming the resist pattern (II) described above. 7 × 15 shots were observed from the sky, and the space width in the IS pattern (38 points in the shot) was measured. A triple value (3σ) of the standard deviation (σ) calculated from the measurement results was determined. The smaller the value of 3σ determined in this manner, the higher the dimension (CD) uniformity of the space width formed in the resist film.
And according to the following evaluation criteria, the evaluation result was shown in Table 3 as "CDU."
Evaluation criteria A: 3σ value is 60 nm or less B: 3σ value is more than 60 nm and less than 70 nm C: 3σ value is 70 nm or more

From the results shown in Table 3, according to the resist pattern forming methods of Examples 4 to 8, it is recognized that the occurrence of defects is reduced and the dimension (CD) uniformity is also high. In particular, when the resist compositions (1), (2) and (3) are used (particularly preferably, when the resist composition (2) is used), it is recognized that these effects can be further enhanced.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the spirit of the present invention. The invention is not limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

A step (i) of forming a resist film having a film thickness of 7 μm or more on a support using a resist composition, a step (ii) of exposing the resist film, and developing the resist film after the exposure to form a resist pattern It is a resist pattern formation method which has a process (iii) to form, Comprising:
The resist composition generates an acid upon exposure, and the solubility in a developer is changed by the action of the acid, and a structural unit (a10) represented by the following general formula (a10-1), and an acid A resin component (A1) having a structural unit (a4) containing a nondissociative aliphatic cyclic group and a structural unit (a1) containing an acid degradable group whose polarity is increased by the action of an acid Resist pattern formation method.

[Wherein, R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms]. Ya x1 is a single bond or a divalent linking group. Wa x1 is an (n ax1 +1) -valent aromatic hydrocarbon group. n ax1 is an integer of 1 to 3. ]
The resist pattern formation method of Claim 1 in which the acid-degradable group in the said structural unit (a1) contains an aliphatic cyclic group.
The resist pattern formation method of Claim 2 in which the acid-decomposable group in the said structural unit (a1) contains the acid dissociative group represented by the following general formula (a1-r2-11).

[Wherein, Ra ′ 10 is a hydrocarbon group having 1 to 10 carbon atoms. Ra ′ ′ 11 is a group which forms a monocyclic aliphatic cyclic group together with the carbon atom to which Ra ′ 10 is bonded. * Is a bond.]
The content rate of the said structural unit (a10) is 45-75 mol% with respect to the total structural unit (100 mol%) which comprises the said resin component (A1) in any one of Claims 1-3. The resist pattern formation method as described.
The content rate of the said structural unit (a1) is 5-20 mol% with respect to the total structural unit (100 mol%) which comprises the said resin component (A1) in any one of Claims 1-4. The resist pattern formation method as described.
The method for forming a resist pattern according to any one of claims 1 to 5, wherein the resist film is irradiated with a KrF excimer laser beam in the step (ii).