JP2007248513A - Positive resist composition and pattern-forming method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition superior in dissolution contrast by simultaneously satisfying high sensitivity, excellent line edge roughness and excellent density independence, and to provide a pattern-forming method using it. <P>SOLUTION: The positive resist composition contains (A) a compound generating acid by irradiation of an active optical beam or radiation, (B) a resin having a repeated unit of a specific structure, and (C) at least a resin selected from a resin increasing dissolubility to alkaline developer by action of acid having a repeated unit of a specific structure, and a resin increasing dissolubility to alkaline developer by action of acid having a repeated unit of a specific structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a positive resist composition suitably used in an ultramicrolithography process such as the manufacture of VLSI and high-capacity microchips and other photo-publishing processes, and a pattern forming method using the same. More particularly, the present invention relates to a positive resist capable of forming a highly refined pattern using KrF excimer laser light, electron beam, EUV light, and the like, and a pattern forming method using the same. KrF excimer laser light, electron The present invention relates to a positive resist composition that can be suitably used for microfabrication of a semiconductor device using a line and EUV light, and a pattern forming method using the same.

  Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a resist composition has been performed. In recent years, with the high integration of integrated circuits, the formation of ultrafine patterns in the submicron region and the quarter micron region has been required. Accordingly, there is a tendency for the exposure wavelength to be shortened from g-line to i-line and further to KrF excimer laser light. Furthermore, at present, in addition to excimer laser light, lithography using electron beams, X-rays, or EUV light is also being developed.

  Lithography using an electron beam or EUV light is positioned as a next-generation or next-generation pattern formation technology, and a highly sensitive positive resist is desired. In particular, high sensitivity is a very important issue for shortening the wafer processing time. However, in positive resists for electron beams and EUV, if high sensitivity is sought, the dependence on density will deteriorate. The development of resists that occur and satisfy these characteristics at the same time is strongly desired. Here, the density dependency means a pattern dimension difference between a portion where the resist pattern density is high and a portion where the resist pattern density is low. If this difference is large, the process margin becomes narrow during actual pattern formation. One of the important issues in resist technology development is how to reduce the size. High sensitivity and good density dependence are in a trade-off relationship, and how to satisfy this simultaneously is very important.

Further, in lithography using KrF excimer laser light, it is also important to satisfy high sensitivity and good density dependence at the same time, and it is necessary to solve these problems.
As a resist suitable for the lithography process using KrF excimer laser light, electron beam, or EUV light, a chemically amplified resist utilizing an acid-catalyzed reaction is mainly used from the viewpoint of high sensitivity. In the resist, as a main component, a phenolic polymer (hereinafter abbreviated as a phenolic acid-decomposable resin) having a property that is insoluble or hardly soluble in an antari developer and becomes soluble in an antari developer by the action of an acid, and A chemically amplified resist composition comprising an acid generator is effectively used.

With respect to these positive resists, several resist compositions using a phenolic acid-decomposable resin obtained by copolymerizing an acid-decomposable acrylate monomer having an alicyclic group as an acid-decomposable group have been known. For example, positive resist compositions disclosed in Patent Documents 1 to 5 can be exemplified.
Patent Document 6 discloses a resist containing a resin containing a repeating unit derived from cinnamic acid ester in order to improve pattern shape and etching resistance.
However, in any combination of these, at present, high sensitivity, good density dependency, and good line edge roughness in the ultrafine region are not satisfied at the same time.

US Pat. No. 5,561,194 JP 2001-166474 A JP 2001-166478 A JP 2003-107708 A JP 2001-194792 A US Pat. No. 6,312,870

  The object of the present invention is to solve the problem of performance improvement technology in microfabrication of semiconductor elements using actinic rays or radiation, in particular, KrF excimer laser light, electron beam or EUV light, and has high sensitivity and good density. It is an object of the present invention to provide a positive resist composition that satisfies both dependency and good line edge roughness and has good dissolution contrast, and a pattern forming method using the same.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by using two kinds of resins having a specific structure, and have reached the present invention.

  The present invention is as follows.

(1) (A) a compound that generates an acid upon irradiation with actinic rays or radiation,
(B) The solubility in an alkali developer is increased by the action of a resin having a repeating unit represented by the following general formula (I) and (C) an acid having a repeating unit represented by the following general formula (A1). And at least one resin selected from resins whose solubility in an alkaline developer is increased by the action of an acid having a repeating unit represented by the following general formula (A2): Resist composition.

In general formula (I),
Ra represents a hydrogen atom or an organic group.
Rb represents a hydrogen atom or an organic group.
n represents an integer of 0 to 2.
In general formula (A1),
A ₁ represents a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid.
In general formula (A2),
A ₂ represents a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid.
X represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or an alkyloxycarbonyl group.

  (2) The positive resist composition as described in (1) above, wherein in the general formula (I), at least one of Ra and Rb is a group capable of leaving by the action of an acid.

(3) In general formula (A2), it is eliminated by the action of an acid in the group in A ₂ that is eliminated by the action of an acid or a group that is decomposed by the action of an acid (acid-decomposable group). The positive resist composition as described in (1), wherein the group has a cyclic carbon structure.

(4) In general formula (A1), it is eliminated by the action of an acid in the group that is eliminated by the action of an acid or a group (acid-decomposable group) that is decomposed by the action of an acid in A ₁ The positive resist composition as described in (1), wherein the group has a cyclic carbon structure.

  (5) In the general formula (I), at least one of groups leaving by the action of an acid in Ra and Rb has a cyclic carbon structure. A positive resist composition.

  (6) A pattern forming method comprising a step of forming a resist film with the positive resist composition according to any one of (1) to (5) above, and exposing and developing the resist film.

  According to the present invention, a positive resist composition having high sensitivity, high density dependency, excellent line edge roughness, and good dissolution contrast with respect to pattern formation by irradiation with an electron beam, KrF excimer laser light, EUV light, etc. A pattern forming method using can be provided.

Hereinafter, the compounds used in the present invention will be described in detail.
In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what has a substituent with what does not have a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

[1] (B) Resin Having Repeating Unit Represented by General Formula (I) The positive resist composition of the present invention comprises a resin having a repeating unit represented by the following general formula (I) (hereinafter referred to as “resin”). (B) ").

In general formula (I),
Ra represents a hydrogen atom or an organic group.
Rb represents a hydrogen atom or an organic group.
n represents an integer of 0 to 2.

Examples of the organic group for Ra in the general formula (I) include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group. The alkyl group is preferably a linear or branched alkyl group having 1 to 15 carbon atoms, specifically, methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, peptyl group, octyl group, Nonyl group, decyl group, etc. can be mentioned. The alkyl group may have a substituent, and examples of the alkyl group having a substituent include a trifluoroalkyl group, a trichloroalkyl group, a hydroxyalkyl group, and a cyanoalkyl group. The cycloalkyl group is preferably a cycloalkyl group having 3 to 30 carbon atoms, and examples thereof include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecanoyl group. . The aryl group is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthryl group. The aralkyl group is preferably an aralkyl group having 7 to 12 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group. Moreover, the organic group may have a hetero atom in the middle. Specifically, an alkoxyalkyl group (preferably 2 to 15 carbon atoms), a cycloalkoxyalkyl group (preferably 4 to 15 carbon atoms), an acylalkyl group (preferably 3 to 15 carbon atoms), an acyloxyalkyl group (preferably Includes 3 to 15 carbon atoms). The organic group having a hetero atom may further have a substituent such as a cycloalkyl group, an aryl group, a cycloalkoxy group, an aryloxy group, a cycloalkylaryloxy group, and an arylcycloalkyloxy group.
The organic group of Rb can mention the same thing as the organic group of Ra.
It is preferable that at least one of Ra and Rb is a group capable of leaving by the action of an acid. Examples of the group capable of leaving by the action of an acid of Ra include the same groups as the group leaving by the action of an acid of A ₁ in formula (A1) described later. Examples of the group capable of leaving by the action of the acid of Rb include the same groups as the group leaving by the action of the acid of A _{2 in} the general formula (A2) described later. The resin (B) is a resin in which at least one of Ra and Rb is a group capable of leaving by the action of an acid, so that the solubility in an alkali developer is increased by the action of the acid.

  Hereinafter, although the specific example of the repeating unit represented by general formula (I) is given, this invention is not limited to this.

  The resin (B) preferably further has a repeating unit represented by the following general formula (II).

In general formula (II),
Rf represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.
Rg represents a hydroxyl group, a halogen atom or an organic group.
n represents an integer of 0 to 4.

In general formula (II), the alkyl group of Rf is preferably an alkyl group having 1 to 5 carbon atoms and may be substituted with a halogen atom, a hydroxyl group or the like.
Examples of the organic group for Rg include an alkyl group (preferably 1 to 10 carbon atoms), a cycloalkyl group (preferably 3 to 10 carbon atoms), an aryl group (preferably 6 to 10 carbon atoms), and an alkoxy group (preferably May include 1 to 10 carbon atoms, an alkoxycarbonyl group (preferably 2 to 10 carbon atoms), an acyloxy group (preferably 2 to 10 carbon atoms), and the like.
The organic group of Rg may be an acid-decomposable group that decomposes by the action of an acid to generate an alkali-soluble group. Examples of the acid-decomposable group for Rg include a group in which a hydrogen atom of a hydroxyl group is substituted with a group capable of leaving by the action of an acid. Examples of the group capable of leaving by the action of an acid include —C (R ₀₁ ) (R ₀₂ ) (OR ₃₉ ), —C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), —C (R ₃₆ ) ( R ₃₇ ) (OR ₃₉ ) and the like. In the formula, R _{01 to} R ₀₂ are each independently a hydrogen atom, an alkyl group (preferably having 1 to 10 carbon atoms), a cycloalkyl group (preferably having 3 to 10 carbon atoms), an aryl group (preferably having 6 carbon atoms). To 10), an aralkyl group (preferably having a carbon number of 7 to 15) or an alkenyl group (preferably having a carbon number of 2 to 10). R _{36 to} R ₃₈ are each independently an alkyl group (preferably 1 to 10 carbon atoms), a cycloalkyl group (preferably 3 to 10 carbon atoms), an aryl group (preferably 6 to 10 carbon atoms), an aralkyl group. (Preferably 7 to 15 carbon atoms) or an alkenyl group (preferably 2 to 10 carbon atoms). R ₃₆ and R ₃₇ may be bonded to each other to form a ring. R ₃₉ is an alkyl group (preferably 1 to 10 carbon atoms), a cycloalkyl group (preferably 3 to 10 carbon atoms), an aryl group (preferably 6 to 10 carbon atoms), an aralkyl group (preferably 7 to 7 carbon atoms). 15) represents an alkenyl group (preferably having 2 to 10 carbon atoms) or a group in which at least two of them are bonded.

  Hereinafter, although the specific example of the repeating unit represented by general formula (II) is given, this invention is not limited to this.

  The resin (B) preferably further has a repeating unit represented by the following general formula (III).

In general formula (III):
Rh represents a hydrogen atom, an alkyl group, a halogen atom or a cyano group.
Ri represents a hydrogen atom or an organic group.

In the general formula (III), the alkyl group of Rh is preferably an alkyl group having 1 to 5 carbon atoms and may be substituted with a halogen atom, a hydroxyl group or the like.
Examples of the organic group for Ri include an alkyl group (preferably 1 to 10 carbon atoms), a cycloalkyl group (preferably 3 to 10 carbon atoms), an aryl group (preferably 6 to 10 carbon atoms), and an aralkyl group (preferably May be a group having 7 to 15 carbon atoms, an alkenyl group (preferably 2 to 10 carbon atoms), or a group in which at least two of them are bonded directly or via an oxy group or a carbonyl group.

  Hereinafter, although the specific example of the repeating unit represented by general formula (III) is given, this invention is not limited to this.

In the resin (B), the content of the repeating unit represented by the general formula (I) is preferably from 10 to 60 mol%, more preferably from 20 to 40 mol%, based on all repeating units.
In the resin (B), the content of the repeating unit represented by the general formula (II) is preferably 5 to 85 mol% and more preferably 50 to 80 mol% in all repeating units.
In the resin (B), the content of the repeating unit represented by the general formula (III) is preferably 5 to 85 mol%, more preferably 50 to 80 mol% in all repeating units.

Resin (B), for example, after dissolving the monomer giving the above repeating unit in an organic solvent such as THF, ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methoxybutanol, etc., under a nitrogen atmosphere and heating conditions, After adding a radical polymerization initiator such as peroxide or azo and reacting with stirring, the mixture is polymerized and then reprecipitated in a poor solvent with respect to the polymerized resin such as hexane and methanol, and filtered to obtain a powder. It can be synthesized by forming. In addition, it is preferable to use the dropping polymerization method in which the monomer dissolved in the solvent and the radical polymerization initiator are added together or separately in the polymerization reaction solution.

  The content of the resin (B) in the positive resist composition is preferably 4 to 15% by mass, more preferably 5 to 10% by mass based on the solid content.

  Hereinafter, although the specific example of resin (B) is given, this invention is not limited to this.

[2] (C) Resin whose solubility in an alkaline developer is increased by the action of an acid having a repeating unit represented by formula (A1) and an acid having a repeating unit represented by formula (A2) Resin whose solubility in alkali developer is increased by the action of at least one acid selected from resins whose solubility in alkali developer is increased by the action The positive resist composition of the present invention has the following general formula (A1) ) Represented by the following general formula (A2) and a resin (hereinafter also referred to as “acid-decomposable resin (A1)”) whose solubility in an alkaline developer is increased by the action of an acid having a repeating unit represented by: At least one resin (hereinafter referred to as “acid-decomposable resin”) selected from resins (hereinafter also referred to as “acid-decomposable resin (A2)”) whose solubility in an alkaline developer is increased by the action of an acid having a repeating unit. (Also referred to as (C) ").

In general formula (A1),
A ₁ represents a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid.
In general formula (A2),
A ₂ represents a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid.
X represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or an alkyloxycarbonyl group.

In general formula (A1), examples of the group capable of leaving by the action of an acid of A ₁ include a tertiary alkyl group such as t-butyl group and t-amyl group, t-butoxycarbonyl group, t- Examples thereof include an acetal group represented by a butoxycarbonylmethyl group, -C (L ₁ ) (L ₂ ) -OZ.
L ₁ and L ₂ may be the same or different and each represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aralkyl group.
Z represents an alkyl group, a cycloalkyl group or an aralkyl group.
Z and L ₁ may be bonded to each other to form a 5- or 6-membered ring.
Examples of the group having a group capable of decomposing by the action of an acid A ₁ include, for example, an alkyl group (preferably having 1 to 10 carbon atoms) having a group (acid-decomposable group) that decomposes by the action of an acid to generate an alkali-soluble group. , A cycloalkyl group having an acid-decomposable group (preferably having 3 to 10 carbon atoms), an aryl group having an acid-decomposable group (preferably having 6 to 10 carbon atoms), and the like.
Examples of the acid-decomposable group include a group in which a hydrogen atom of an alkali-soluble group such as a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, or a thiol group is protected with a group capable of leaving by the action of an acid. .
Examples of the group capable of leaving by the action of an acid include —C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), —C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), —C (═O) — _{O-C (R 36) (} R 37) (R 38), - C (R 01) (R 02) (OR 39), - C (R 01) (R 02) -C (= O) -O- C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ) and the like can be mentioned.
In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
R _{01 and} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
In the acid-decomposable resin (A1), when A ₁ is a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid, the solubility in an alkali developer is increased by the action of the acid. To do.

The alkyl groups and cycloalkyl groups of L ₁ , L ₂ and Z are methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, cyclopentyl group, hexyl group, Examples thereof include a linear or branched alkyl group having 1 to 20 carbon atoms, such as a cyclohexyl group, an octyl group, and a dodecyl group, and a cycloalkyl group. These groups may have a substituent.
Preferred substituents that the alkyl group and cycloalkyl group of L ₁ , L ₂ and Z may have include an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a nitro group, an acyl group, an acyloxy group, an acylamino group, and a sulfonylamino group. , An alkylthio group, an arylthio group, an aralkylthio group, a thiophenecarbonyloxy group, a thiophenemethylcarbonyloxy group, a heterocyclic residue such as a pyrrolidone residue, and the like, preferably having 12 or less carbon atoms.
Examples of the alkyl group having a substituent include a cyclohexylethyl group, an alkylcarbonyloxymethyl group, an alkylcarbonyloxyethyl group, a cycloalkylcarbonyloxymethyl group, a cycloalkylcarbonyloxyethyl group, an arylcarbonyloxyethyl group, and an aralkylcarbonyloxyethyl group. , Alkyloxymethyl group, cycloalkyloxymethyl group, aryloxymethyl group, aralkyloxymethyl group, alkyloxyethyl group, cycloalkyloxyethyl group, aryloxyethyl group, aralkyloxyethyl group, alkylthiomethyl group, cycloalkylthiomethyl Group, arylthiomethyl group, aralkylthiomethyl group, alkylthioethyl group, cycloalkylthioethyl group, arylthioethyl group, aralkyl Oechiru group, and the like.
The alkyl and cycloalkyl in these groups are not particularly limited, and may further have a substituent such as the aforementioned alkyl group, cycloalkyl group, alkoxy group and the like.
Examples of the alkylcarbonyloxyethyl group and cycloalkylcarbonyloxyethyl group include cyclohexylcarbonyloxyethyl group, t-butylcyclohexylcarbonyloxyethyl group, n-butylcyclohexylcarbonyloxyethyl group, and the like.
Aryl is not particularly limited, but generally includes those having 6 to 14 carbon atoms such as phenyl group, xylyl group, toluyl group, cumenyl group, naphthyl group, anthracenyl group, and the above-mentioned alkyl group and cycloalkyl group. And may have a substituent such as an alkoxy group.
Examples of the aryloxyethyl group include a phenyloxyethyl group, a cyclohexylphenyloxyethyl group, and the like. These groups may further have a substituent.
Aralkyl is not particularly limited, and examples thereof include a benzyl group.
Examples of the aralkylcarbonyloxyethyl group include a benzylcarbonyloxyethyl group. These groups may further have a substituent.

Examples of the aralkyl group of L ₁ , L ₂ and Z include those having 7 to 15 carbon atoms such as benzyl group and phenethyl group. These groups may have a substituent.
Preferred substituents for the aralkyl group include an alkoxy group, a hydroxyl group, a halogen atom, a nitro group, an acyl group, an acylamino group, a sulfonylamino group, an alkylthio group, an arylthio group, an aralkylthio group, and the like, and an aralkyl group having a substituent Examples thereof include an alkoxybenzyl group, a hydroxybenzyl group, and a phenylthiophenethyl group. The range of the carbon number of the substituent which the aralkyl group as L1 to L2 and Z can have is preferably 12 or less.

Examples of the 5- or 6-membered ring formed by combining Z and L ₁ with each other include a tetrahydropyran ring and a tetrahydrofuran ring.

  Z is preferably a linear or branched alkyl group. Thereby, the effect of the present invention becomes more remarkable.

  The acid-decomposable resin (A1) is prepared by, for example, dissolving a polymer having a phenolic hydroxyl group, preferably in an organic solvent, dehydrating water in the system by a technique such as azeotropic distillation, and then adding an alkyl vinyl ether compound and an acid catalyst. Then, an acetalization reaction is performed, and a desired acetal group can be introduced into the phenolic hydroxyl group.

The polymer having a phenolic hydroxyl group is preferably a polymer of hydroxystyrenes.
Moreover, it is also preferable that the repeating unit derived from the acid-decomposable (meth) acrylic acid tertiary alkyl ester such as t-butyl acrylate or t-butyl methacrylate is included.

  Moreover, a non-acid-decomposable group can also be introduce | transduced into the polymer which has a phenolic hydroxyl group for the purpose of adjusting the alkali solubility of acid-decomposable resin (A1). Non-acid-decomposable groups can be introduced by copolymerizing styrenes, non-acid-decomposable (meth) acrylic esters, non-acid-decomposable (meth) acrylic amides, hydroxystyrenes, A method of protecting the hydroxyl group with a non-acid-decomposable substituent is preferred.

  As a substituent of the non-acid-decomposable group, an acetyl group, a mesyl group, a toluenesulfonyl group and the like are preferable, but not limited thereto.

  Examples of the styrenes include styrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene, iodostyrene, methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, methoxystyrene, ethoxystyrene, phenylstyrene, t-butylstyrene, t -Butoxystyrene and the like can be mentioned, and styrene, methylstyrene, t-butylstyrene, and t-butoxystyrene are particularly preferable.

  Examples of the non-acid-decomposable (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, allyl (meth) acrylate, and glycidyl (meth) acrylate. , Benzyl (meth) acrylate, hydroxyethyl (meth) acrylate, and the like.

  Non-acid-decomposable (meth) acrylic acid amides include (meth) acrylic acid amide, (meth) acrylic acid phenylamide, (meth) acrylic acid isopropylamide and the like.

  Furthermore, examples of the copolymerizable monomer include maleic acid derivatives, maleic anhydride derivatives, (meth) acrylonitrile, vinyl pyrrolidone, vinyl pyridine, and vinyl acetate.

  As described above, a copolymer component and / or a non-acid-decomposable group is added to the polymer having a phenolic hydroxyl group as long as the alkali solubility of the acid-decomposable resin (A1) is adjusted and the alkali developability is not impaired. Although it is possible to introduce, in general, among the components constituting the polymer having a phenolic hydroxyl group, the hydroxystyrene component occupies 60 mol% or more, preferably 70 mol% or more of dry etching resistance and sensitivity. Desirable in terms.

  The weight average molecular weight of the trunk polymer (polymer having a phenolic hydroxyl group) can be measured as a polystyrene-equivalent molecular weight (Mw) by gel permeation chromatography (GPC), and preferably from 2000 to 200 in terms of resolving power. 2,000, 2,500 to 20,000 being particularly preferred.

  The molecular weight dispersion (dispersion degree: Mw / Mn) of the polymer is preferably from 1.0 to 3.0, more preferably from 1.0 to 1.5, more preferably from the viewpoint of line edge roughness. Preferably it is 1.0-1.3.

  Such a polymer with a small molecular weight dispersion changes various polymer synthesis conditions (amount of polymerization solvent, amount of polymerization initiator) and polymer purification conditions (type / amount of reprecipitation solvent, number of reprecipitation operations). Can be obtained. For example, the molecular weight can be adjusted by changing the amount of the polymerization solvent or initiator, and the degree of dispersion of the resin can be reduced by changing the reprecipitation solvent or increasing the number of reprecipitation operations. As the reprecipitation solvent, it is preferable to use a mixture of two or more solvents, or to perform the reprecipitation operation twice or more, and to perform the reprecipitation operation using a reprecipitation solvent in which two or more solvents are mixed. More preferably, it is performed more than once. Alternatively, it can also be synthesized by synthesizing polyvinylphenol having a low molecular weight dispersity via a living anion, living radical, or living cation polymerization method, and then acetalizing using alkyl vinyl ethers.

  As the alkyl vinyl ether compound used in the acetalization reaction, a compound represented by the following general formula (A) is desirable.

In general formula (A),
R ₁ represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, or an aralkyl group which may have a substituent. To express.
Rs and Rt each independently represents an optionally substituted alkyl group or an optionally substituted cycloalkyl group.

The alkyl group which may have a substituent for R ₁ , Rs and Rt is preferably a straight chain or branched chain having 1 to 20 carbon atoms, more preferably 1 to 18 carbon atoms. For example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, i-pentyl group, t-pentyl Group, n-hexyl group, i-hexyl group, t-hexyl group, n-heptyl group, i-heptyl group, t-heptyl group, n-octyl group, i-octyl group, t-octyl group, n-nonyl Group, i-nonyl group, t-nonyl group, n-decyl group, i-decyl group, t-decyl group, n-undecyl group, i-undecyl group, n-dodecyl group, i-dodecyl group, n-tridecyl group Group, i-tridecyl group, n-tetradecyl group, i- Tradecyl group, n-pentadecyl group, i-pentadecyl group, n-hexadecyl group, i-hexadecyl group, n-heptadecyl group, i-heptadecyl group, n-octadecyl group, i-octadecyl group, n-nonadecyl group, i- Nonadecyl group etc. can be mentioned.
These substituents may be substituted by the substituents shown below.

The cycloalkyl group which may have a substituent for R ₁ , Rs and Rt preferably forms a ring having 3 to 20 carbon atoms, more preferably 3 to 18 carbon atoms and up to 20 carbon atoms. In some cases, a cyclic alkyl having a substituent may be used, for example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cycloundecyl group, a cyclododecyl group, Cyclotridecyl group, cyclotridecyl group, cyclotetradecyl group, cyclopentadecyl group, cyclohexadecyl group, cycloheptadecyl group, cyclooctadecyl group, cyclononadecyl group, 4-cyclohexylcyclohexyl group, 4-n-hexylcyclohexyl group , Pentanylcyclohexyl group, hexyloxy Cyclohexyl group, and a penta oxy cyclohexyl group. Substituted cyclic alkyl groups other than those listed here can also be used within the above ranges.
These substituents may be substituted by the substituents shown below.

The aryl group which may have a substituent for R ₁ is preferably 6 to 30 carbon atoms, preferably 6 to 25 carbon atoms, such as phenyl group, tolyl group, xylyl group, ethylphenyl group, Propylphenyl group, methoxyphenyl group, ethoxyphenyl group, propyloxyphenyl group, 4-cyclopentylphenyl group, 4-cyclohexylphenyl group, 4-cycloheptenylphenyl group, 4-cyclooctanylphenyl group, 2-cyclopentylphenyl group 2-cyclohexylphenyl group, 2-cycloheptenylphenyl group, 2-cyclooctanylphenyl group, 3-cyclopentylphenyl group, 3-cyclohexylphenyl group, 3-cycloheptenylphenyl group, 3-cyclooctanylphenyl group 4-cyclopentyloxyphenyl group, 4- Cyclohexyloxyphenyl group, 4-cycloheptenyloxyphenyl group, 4-cyclooctanyloxyphenyl group, 2-cyclopentyloxyphenyl group, 2-cyclohexyloxyphenyl group, 2-cycloheptenyloxyphenyl group, 2-cyclo Octanyloxyphenyl group, 3-cyclopentyloxyphenyl group, 3-cyclohexyloxyphenyl group, 3-cycloheptenyloxyphenyl group, 3-cyclooctenyloxyphenyl group, 4-n-pentylphenyl group, 4-n- Hexylphenyl group, 4-n-heptenylphenyl group, 4-n-octanylphenyl group, 2-n-pentylphenyl group, 2-n-hexylphenyl group, 2-n-heptenylphenyl group, 2-n -Octanylphenyl group, 3-n-pentylphenyl group, 3- n-hexylphenyl group, 3-n-heptenylphenyl group, 3-n-octanylphenyl group, 2,6-di-isopropylphenyl group, 2,3-di-isopropylphenyl group, 2,4-di- Isopropylphenyl group, 3,4-di-isopropylphenyl group, 3,6-di-t-butylphenyl group, 2,3-di-t-butylphenyl group, 2,4-di-t-butylphenyl group, 3,4-di-t-butylphenyl group, 2,6-di-n-butylphenyl group, 2,3-di-n-butylphenyl group, 2,4-di-n-butylphenyl group, 3, 4-di-n-butylphenyl group, 2,6-di-i-butylphenyl group, 2,3-di-i-butylphenyl group, 2,4-di-i-butylphenyl group, 3,4- Di-i-butylphenyl group, 2,6-di-t-amylphenyl 2,3-di-t-amylphenyl group, 2,4-di-t-amylphenyl group, 3,4-di-t-amylphenyl group, 2,6-di-i-amylphenyl group, 2 , 3-di-i-amylphenyl group, 2,4-di-i-amylphenyl group, 3,4-di-i-amylphenyl group, 2,6-di-n-pentylphenyl group, 2,3 -Di-n-pentylphenyl group, 2,4-di-n-pentylphenyl group, 3,4-di-n-pentylphenyl group, 4-adamantylphenyl group, 2-adamantylphenyl group, 4-isoboronyl Phenyl group, 3-isobornylphenyl group, 2-isobornylphenyl group, 4-cyclopentyloxyphenyl group, 4-cyclohexyloxyphenyl group, 4-cycloheptenyloxyphenyl group, 4-cyclooctanyloxyphene Group, 2-cyclopentyloxyphenyl group, 2-cyclohexyloxyphenyl group, 2-cycloheptenyloxyphenyl group, 2-cyclooctanyloxyphenyl group, 3-cyclopentyloxyphenyl group, 3-cyclohexyloxyphenyl group, 3 -Cycloheptenyloxyphenyl group, 3-cyclooctanyloxyphenyl group, 4-n-pentyloxyphenyl group, 4-n-hexyloxyphenyl group, 4-n-heptenyloxyphenyl group, 4-n-octa Nyloxyphenyl group, 2-n-pentyloxyphenyl group, 2-n-hexyloxyphenyl group, 2-n-heptenyloxyphenyl group, 2-n-octanyloxyphenyl group, 3-n-pentyloxyphenyl Group, 3-n-hexyloxyphenyl group, 3-n-hepteni Ruoxyphenyl group, 3-n-octanyloxyphenyl group, 2,6-di-isopropyloxyphenyl group, 2,3-di-isopropyloxyphenyl group, 2,4-di-isopropyloxyphenyl group, 3, 4-di-isopropyloxyphenyl group, 2,6-di-t-butyloxyphenyl group,
2,3-di-t-butyloxyphenyl group, 2,4-di-t-butyloxyphenyl group, 3,4-di-t-butyloxyphenyl group, 2,6-di-n-butyloxyphenyl group Group, 2,3-di-n-butyloxyphenyl group, 2,4-di-n-butyloxyphenyl group, 3,4-di-n-butyloxyphenyl group, 2,6-di-i-butyl Oxyphenyl group, 2,3-di-i-butyloxyphenyl group, 2,4-di-i-butyloxyphenyl group, 3,4-di-i-butyloxyphenyl group, 2,6-di-t -Amyloxyphenyl group, 2,3-di-t-amyloxyphenyl group, 2,4-di-t-amyloxyphenyl group, 3,4-di-t-amyloxyphenyl group, 2,6-di -I-amyloxyphenyl group, 2,3-di-i-amyloxy Phenyl group, 2,4-di-i-amyloxyphenyl group, 3,4-di-i-amyloxyphenyl group, 2,6-di-n-pentyloxyphenyl group, 2,3-di-n- Pentyloxyphenyl group, 2,4-di-n-pentyloxyphenyl group, 3,4-di-n-pentyloxyphenyl group, 4-adamantyloxyphenyl group, 3-adamantyloxyphenyl group, 2-adamantyloxyphenyl Group, 4-isoboronyloxyphenyl group, 3-isoboronyloxyphenyl group, 2-isoboronyloxyphenyl group, and the like. These may be further substituted as long as they are within the above ranges. It is not limited to the substituent of.
These substituents may be substituted by the substituents shown below.

The aralkyl group which may have a substituent for R ₁ is preferably 7 to 30 carbon atoms, more preferably 8 to 25 carbon atoms, for example, phenylethyl group, tolylphenylethyl group, xylylphenylethyl group. Ethylphenylethyl group, propylphenylethyl group, 4-cyclopentylphenylethyl group, 4-cyclohexylphenylethyl group, 4-cycloheptenylphenylethyl group, 4-cyclooctanylphenylethyl group, 2-cyclopentylphenylethyl group, 2-cyclohexylphenylethyl group, 2-cycloheptenylphenylethyl group, 2-cyclooctanylphenylethyl group, 3-cyclopentylphenylethyl group, 3-cyclohexylphenylethyl group, 3-cycloheptenylphenylethyl group, 3- Cyclooctanylpheny Ethyl group, 4-cyclopentyloxyphenylethyl group, 4-cyclohexyloxyphenylethyl group, 4-cycloheptenyloxyphenylethyl group, 4-cyclooctanyloxyphenylethyl group, 2-cyclopentyloxyphenylethyl group, 2-cyclohexyl Oxyphenylethyl group, 2-cycloheptenyloxyphenylethyl group, 2-cyclooctanyloxyphenylethyl group, 3-cyclopentyloxyphenylethyl group, 3-cyclohexyloxyphenylethyl group, 3-cycloheptenyloxyphenylethyl group 3-cyclooctanyloxyphenylethyl group, 4-n-pentylphenylethyl group, 4-n-hexylphenylethyl group, 4-n-heptenylphenylethyl group, 4-n-octanylphenylethyl group, 2-n-pentylphenylethyl group, 2-n-hexylphenylethyl group, 2-n-heptenylphenylethyl group, 2-n-octanylphenylethyl group, 3-n-pentylphenylethyl group, 3-n -Hexylphenylethyl group, 3-n-heptenylphenylethyl group, 3-n-octanylphenylethyl group, 2,6-di-isopropylphenylethyl group, 2,3-diisopropylphenylethyl group, 2, 4-di-isopropylphenylethyl group, 3,4-di-isopropylphenylethyl group, 2,6-di-t-butylphenylethyl group, 2,3-di-t-butylphenylethyl group, 2,4- Di-t-butylphenylethyl group, 3,4-di-t-butylphenylethyl group, 2,6-di-n-butylphenylethyl group, 2,3-di-n-butyl group Ruphenylethyl group, 2,4-di-n-butylphenylethyl group, 3,4-di-n-butylphenylethyl group, 2,6-di-i-butylphenylethyl group, 2,3-di- i-butylphenylethyl group, 2,4-di-i-butylphenylethyl group, 3,4-di-i-butylphenylethyl group, 2,6-di-t-amylphenylethyl group, 2,3- Di-t-amylphenylethyl group, 2,4-di-t-amylphenylethyl group, 3,4-di-t-amylphenylethyl group, 2,6-di-i-amylphenylethyl group, 2, 3-di-i-amylphenylethyl group, 2,4-di-i-amylphenylethyl group, 3,4-di-i-amylphenylethyl group, 2,6-di-n-pentylphenylethyl group, 2,3-di-n-pentylphenylethyl group, , 4-Di-n-pentylphenylethyl group, 3,4-di-n-pentylphenylethyl group, 4-adamantylphenylethyl group, 3-adamantylphenylethyl group, 2-adamantylphenylethyl group, 4-isoboro Nylphenylethyl group, 3-isobornylphenylethyl group, 2-isobornylphenylethyl group, 4-cyclopentyloxyphenylethyl group, 4-cyclohexyloxyphenylethyl group, 4-cycloheptenyloxyphenylethyl group, 4 -Cyclooctanyloxyphenylethyl group, 2-cyclopentyloxyphenylethyl group, 2-cyclohexyloxyphenylethyl group, 2-cycloheptenyloxyphenylethyl group, 2-cyclooctanyloxyphenylethyl group, 3-cyclopentyloxyphenyl group Echi Group, 3-cyclohexyloxyphenylethyl group, 3-cycloheptenyloxyphenylethyl group, 3-cyclooctanyloxyphenylethyl group, 4-n-pentyloxyphenylethyl group, 4-n-hexyloxyphenylethyl Group, 4-n-heptenyloxyphenylethyl group, 4-n-octanyloxyphenylethyl group, 2-n-pentyloxyphenylethyl group, 2-n-hexyloxyphenylethyl group, 2-n-heptenyl Oxyphenylethyl group, 2-n-octanyloxyphenylethyl group, 3-n-pentyloxyphenylethyl group, 3-n-hexyloxyphenylethyl group, 3-n-heptenyloxyphenylethyl group, 3-n -Octanyloxyphenyl ethyl group, 2,6-diisopropyloxyphenyl Til group, 2,3-di-isopropyloxyphenylethyl group, 2,4-di-isopropyloxyphenylethyl group, 3,4-diisopropyloxyphenylethyl group, 2,6-di-t-butyloxyphenylethyl Group, 2,3-di-t-butyloxyphenylethyl group, 2,4-di-t-butyloxyphenylethyl group, 3,4-di-t-butyloxyphenylethyl group, 2,6-di- n-butyloxyphenylethyl group, 2,3-di-n-butyloxyphenylethyl group, 2,4-di-n-butyloxyphenylethyl group, 3,4-di-n-butyloxyphenylethyl group, 2,6-di-i-butyloxyphenylethyl group, 2,3-di-i-butyloxyphenylethyl group, 2,4-di-i-butyloxyphenylethyl group, 3,4 Di-i-butyloxyphenylethyl group, 2,6-di-t-amyloxyphenylethyl group, 2,3-di-t-amyloxyphenylethyl group, 2,4-di-t-amyloxyphenylethyl group Group, 3,4-di-t-amyloxyphenylethyl group, 2,6-di-i-amyloxyphenylethyl group, 2,3-di-i-amyloxyphenylethyl group, 2,4-di- i-amyloxyphenylethyl group, 3,4-di-i-amyloxyphenylethyl group, 2,6-di-n-pentyloxyphenylethyl group, 2,3-di-n-pentyloxyphenylethyl group, 2,4-di-n-pentyloxyphenylethyl group, 3,4-di-n-pentyloxyphenylethyl group, 4-adamantyloxyphenylethyl group, 3-adamantyloxypheny Ruethyl group, 2-adamantyloxyphenylethyl group, 4-isoboronyloxyphenylethyl group, 3-isoboronyloxyphenylethyl group, 2-isoboronyloxyphenylethyl group, or the above alkyl is methyl group, propyl And those substituted with a butyl group or the like.
These substituents may be substituted by the substituents shown below.

  As further substituents of the above groups, hydroxyl groups, halogen atoms (fluorine, chlorine, bromine, iodine), nitro groups, cyano groups, the above alkyl groups, methoxy groups, ethoxy groups, hydroxyethoxy groups, propoxy groups Hydroxypropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, alkoxy group such as t-butoxy group, alkoxycarbonyl group such as methoxycarbonyl group, ethoxycarbonyl group, benzyl group, phenethyl group, cumyl group, etc. Aralkyl groups, aralkyloxy groups, formyl groups, acetyl groups, butyryl groups, benzoyl groups, cyanyl groups, acyl groups such as valeryl groups, acyloxy groups such as butyryloxy groups, the above alkenyl groups, vinyloxy groups, propenyloxy groups, allyloxy groups Alkenyloxy such as butenyloxy group , Mention may be made of the above aryl group, an aryloxy group such as phenoxy group, aryloxycarbonyl group such as benzoyloxy group.

  These substituents may further have a substituent, as long as the carbon number of the substituted aryl group or the substituted aralkyl group is within this range.

  Specific examples of the compound represented by the general formula (A) include ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, cyclohexyl vinyl ether, n-hexyl vinyl ether, benzyl vinyl ether, cyclohexyl ethyl. Vinyl ether, phenoxyethyl vinyl ether, cyclohexylphenoxyethyl vinyl ether, 4-carbonylcyclohexylphenoxyethyl vinyl ether, t-butylcyclohexylcarbonyloxyethyl vinyl ether, cyclohexylthioethyl vinyl ether, n-butylcyclohexylcarbonyloxyethyl vinyl ether, and the like. Aceter with phenolic hydroxyl group in polymer As long as it causes the reaction, but it is not limited to those described above. In the above, t-butyl vinyl ether, isopropyl vinyl ether, and cyclohexyl vinyl ether are preferable, and t-butyl vinyl ether is more preferable. In addition, isopropenyl ethers such as methyl isopropenyl ether, butyl isopropenyl ether, phenyl isopropenyl ether, benzyl isopropenyl ether, cyclohexyl isopropenyl ether, cyclohexylphenoxyethyl isopropenyl ether, and the like are also preferable.

  The amount of the alkyl vinyl ether compound used in the reaction is preferably 5 mol% to 95 mol%, more preferably 10 mol% to 60 mol, based on the phenolic hydroxyl group in the polymer having a phenolic hydroxyl group. %, And more preferably 15 mol% to 50 mol%.

The organic solvent used in the reaction is not particularly limited as long as it is an inert solvent, and examples thereof include propylene glycol methyl ether acetate (PGMEA), 2-heptanone, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, and tetrahydrofuran. be able to. Of these, PGMEA and 2-heptanone are preferable.
The reaction solvent is usually used in an amount of 100 to 1000 parts by mass with respect to 100 parts by mass of the polymer having a phenolic hydroxyl group.

  The acid-decomposable resin (A1) can be used alone or in combination of two or more. Also, a combination of acid-decomposable resins (A1) synthesized from polymers having two or more phenolic hydroxyl groups having different molecular weights and composition ratios of polymers having phenolic hydroxyl groups, and two or more acid decompositions having different acetal protection rates Combinations of the functional resin (A1) can also be selected to exhibit sensitivity, resolution, profile, and other resist characteristics.

  The synthesis of the acid-decomposable resin (A1) is carried out by dissolving a polymer having a phenolic hydroxyl group in the organic solvent (a solvent inert to the acetalization reaction) shown above, and by distillation under reduced pressure as necessary. Water is removed and an alkyl vinyl ether compound is added. The acetalization reaction proceeds by adding an acidic catalyst.

  As the acid catalyst, either an inorganic acid or an organic acid can be used. The organic acid is preferable because it has no residual metal impurities, and p-toluenesulfonic acid, p-toluenesulfonic acid pyridinium salt, and the like are more preferable.

For the purpose of stopping the acetalization reaction, neutralization with a base compound is preferably performed. If this neutralization is not performed, there is a possibility that an acid remains and impairs the storage stability of the resist. The basic compound to be used is not particularly limited as long as the acid as the added catalyst is neutralized and the salt is removed in the water washing step. Among these, organic base compounds are preferable because they have no residual metal impurities, and specific examples include triethylamine, trimethylamine, pyridine, aminopyridine, piperazine, imidazole, and the like, and triethylamine and pyridine are particularly preferable.

  After the acetalization reaction is completed and neutralized, it is preferable to remove the salt remaining in the system using ultrapure water or the like.

  Specific examples of the acid-decomposable resin (A1) include the following.

  In the acid-decomposable resin (A1), the content of the repeating unit represented by the general formula (A1) is preferably 5 to 50 mol%, more preferably 10 to 35 mol% in all repeating units.

The weight average molecular weight of the acid-decomposable resin (A1) can be measured as a polystyrene-equivalent molecular weight (Mw) by gel permeation chromatography (GPC), and is preferably 2000 to 200,000 in terms of resolving power. 2,500 to 20,000 is particularly preferred.

  The molecular weight dispersion (dispersion degree: Mw / Mn) of the acid-decomposable resin (A1) is preferably 1.0 to 3.0, more preferably 1.0 from the viewpoint of line edge roughness. It is -1.5, More preferably, it is 1.0-1.3.

In the general formula (A2), the alkyl group in the alkyl group and alkyloxycarbonyl group of X is preferably an alkyl group having 1 to 5 carbon atoms. The alkyl group of X may have a substituent. Examples of the alkyl group having a substituent include a trifluoromethyl group, an alkyloxycarbonylmethyl group, an alkylcarbonyloxymethyl group, a hydroxymethyl group, and an alkoxymethyl group. Groups and the like.
In general formula (A2), examples of the group capable of leaving by the action of the acid of A ₂ include tertiary alkyl groups such as t-butyl and t-amyl, but include an alicyclic hydrocarbon group. Is preferred.
Examples of the group having a group capable of decomposing by the action of an acid A ₂ include, for example, an alkyl group (preferably having 1 to 10 carbon atoms) having a group (acid-decomposable group) that decomposes by the action of an acid to generate an alkali-soluble group. , A cycloalkyl group having an acid-decomposable group (preferably having 3 to 10 carbon atoms), an aryl group having an acid-decomposable group (preferably having 6 to 10 carbon atoms), and the like.
Examples of the acid-decomposable group include a group in which a hydrogen atom of an alkali-soluble group such as a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, or a thiol group is protected with a group capable of leaving by the action of an acid. .
Examples of the group capable of leaving by the action of an acid include —C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), —C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), —C (═O) — _{O-C (R 36) (} R 37) (R 38), - C (R 01) (R 02) (OR 39), - C (R 01) (R 02) -C (= O) -O- C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ) and the like can be mentioned.
In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
R _{01 and} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
In the acid-decomposable resin (A2), since A ₂ is a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid, the solubility in an alkali developer is increased by the action of the acid. To do.

The group capable of leaving by the action of an acid of A ₂ is preferably the following general formula (pI) to general formula (pVI).

Where
R ₁₁ represents an alkyl group, and Z represents an atomic group necessary for forming an alicyclic hydrocarbon group together with a carbon atom.
R _{12 to} R ₁₆ each independently represents an alkyl group or an alicyclic hydrocarbon group. At least one of R _{12 to} R ₁₄ , or any of R ₁₅ and R ₁₆ is preferably an alicyclic hydrocarbon group.
R _{17 to} R ₂₁ each independently represents a hydrogen atom, an alkyl group or an alicyclic hydrocarbon group. At least one of R _{17 to} R ₂₁ is preferably an alicyclic hydrocarbon group. Moreover, any of R ₁₉ and R ₂₁ represents an alkyl group or an alicyclic hydrocarbon group.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, an alkyl group or an alicyclic hydrocarbon group. At least one of R _{22 to} R ₂₅ is preferably an alicyclic hydrocarbon group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

In the general formulas (pI) to (pVI), the alkyl group in R _{11 to} R ₂₅ may be either substituted or unsubstituted, and a linear or branched alkyl group having 1 to 4 carbon atoms. Are preferable, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group.
As further substituents for the alkyl group, an alkoxy group having 1 to 4 carbon atoms, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), acyl group, acyloxy group, cyano group, hydroxyl group, carboxy group, An alkoxycarbonyl group, a nitro group, etc. can be mentioned.

The alicyclic hydrocarbon group in R _{12 to} R _{25 or} the alicyclic hydrocarbon group formed by Z and a carbon atom may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25. These alicyclic hydrocarbon groups may have a substituent.

  Below, the structural example of an alicyclic part is shown among alicyclic hydrocarbon groups.

In the present invention, preferred examples of the alicyclic moiety include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclohexyl group, cycloheptyl. Group, cyclooctyl group, cyclodecanyl group and cyclododecanyl group. More preferred are an adamantyl group, a decalin residue, a norbornyl group, a cedrol group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group, and a cyclododecanyl group.

  Examples of the substituent for these alicyclic hydrocarbon groups include an alkyl group, a halogen atom, a hydroxyl group, an alkoxy group, a carboxyl group, and an alkoxycarbonyl group. The alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group or a butyl group, more preferably a methyl group, an ethyl group, a propyl group or an isopropyl group. Examples of the alkoxy group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. The alkyl group and the alkoxy group may have a further substituent. Examples of further substituents on the alkyl group and alkoxy group include a hydroxyl group, a halogen atom, and an alkoxy group.

The group that is eliminated by the action of the acid of A ₂ is particularly preferably a group represented by the following general formula (3).

In general formula (3),
R ₄ , R ₅ , and Y each independently represent an alkyl group or an alicyclic hydrocarbon group.

The group represented by the general formula (3) is preferably a group in which one of R _{12 to} R ₁₄ is an alicyclic group in the general formula (pII).

  Hereinafter, although the specific example of the monomer corresponding to the repeating unit represented by general formula (A2) is shown, this invention is not limited to this.

  The acid-decomposable resin (A2) preferably further has a repeating unit represented by the general formula (II) in the resin (B).

The acid-decomposable resin (A2) preferably has 5 to 40 mol%, more preferably 10 to 30 mol% of the repeating unit represented by the general formula (A2) in all repeating units. More preferred.
The acid-decomposable resin (A2) preferably has 30 to 85 mol%, more preferably 50 to 80 mol% of the repeating unit represented by the general formula (II) in all repeating units. More preferred.

  For example, the acid-decomposable resin (A2) is obtained by dissolving the monomer giving the above repeating unit in an organic solvent such as THF, ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methoxybutanol, etc. Under the condition, a radical polymerization initiator such as peroxide or azo is added and reacted with stirring to polymerize, and then reprecipitated in a poor solvent for the polymerized resin such as hexane and methanol, and filtered. And can be synthesized by pulverization. In addition, it is preferable to use the dropping polymerization method in which the monomer dissolved in the solvent and the radical polymerization initiator are added together or separately in the polymerization reaction solution.

  The weight average molecular weight of the acid-decomposable resin (A2) can be measured as a polystyrene-equivalent molecular weight (Mw) by gel permeation chromatography (GPC), and is preferably 2000 to 200,000 in terms of resolution. 2,500 to 20,000 is particularly preferred.

  The molecular weight dispersion (dispersion degree: Mw / Mn) of the acid-decomposable resin (A2) is preferably 1.0 to 3.0, more preferably 1.0 from the viewpoint of line edge roughness. It is -1.5, More preferably, it is 1.0-1.3.

  Hereinafter, although the specific example of acid-decomposable resin (A2) is given, this invention is not limited to this.

  As content in the composition of acid-decomposable resin (C), it is 70-98 mass% normally with respect to the mass of the total solid of this composition, Preferably it is 75-96 mass%, More preferably Is 80-96 mass%.

[3] (A) Compound that generates an acid upon irradiation with actinic rays or radiation A compound that generates an acid upon irradiation with actinic rays or radiation contained in the positive resist composition of the present invention (hereinafter also referred to as “acid generator”) Is preferably a compound that generates sulfonic acid upon irradiation with actinic rays or radiation.
A compound that generates sulfonic acid upon irradiation with actinic rays or radiation (hereinafter also referred to as “sulfonic acid generator”) generates sulfonic acid upon irradiation with actinic rays or radiation such as KrF excimer laser light, electron beam, EUV, etc. Examples of the compound include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

  Further, a group in which a sulfonic acid is generated by irradiation of these actinic rays or radiation, or a compound in which the compound is introduced into the main chain or side chain of the polymer, for example, US Pat. No. 3,849,137, German Patent No. 3914407. JP, 63-26653, JP 55-164824, JP 62-69263, JP 63-146038, JP 63-163452, JP 62-153853, The compounds described in JP-A-63-146029 can be used.

  Further, compounds capable of generating a sulfonic acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  In the present invention, examples of sulfonic acid generators that are preferable from the viewpoint of improving image performance such as resolution and pattern shape include sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, and disulfones.

  Preferable examples of the sulfonic acid generator include compounds represented by the following general formulas (ZI), (ZII), and (ZIII).

In the general formula (ZI),
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group. Two of R ₂₀₁ to R ₂₀₃ are bonded to the ring structure may be formed.
X ⁻ represents an organic sulfonate anion.

The carbon number of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ is generally 1-30, preferably 1-20.

The two of the group formed by bonding of the R ₂₀₁ to R _203, an alkylene group (e.g., butylene, pentylene), and an example of an oxygen atom, a sulfur atom, an ester bond, an amide bond And may contain a carbonyl group.

Specific examples of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ include corresponding groups in the compounds (ZI-1), (ZI-2) and (ZI-3) described later.

In addition, the compound which has two or more structures represented by general formula (ZI) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (ZI) is, at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (ZI) It may be a compound.

  More preferred (ZI) components include compounds (ZI-1), (ZI-2) and (ZI-3) described below.

The compound (ZI-1) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (ZI), arylsulfonium compound, i.e., a compound having arylsulfonium as a cation.

In the arylsulfonium compound, all of R _{201 to} R ₂₀₃ may be an aryl group, or a part of R _{201 to} R ₂₀₃ may be an aryl group, and the rest may be an alkyl group or a cycloalkyl group.

  Examples of the arylsulfonium compound include triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, aryldicycloalkylsulfonium compounds, and the like.

  Examples of the aryl group of the arylsulfonium compound include an aryl group composed of a hydrocarbon and a heteroaryl group having a hetero atom such as a nitrogen atom, a sulfur atom, or an oxygen atom. The aryl group composed of hydrocarbon is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. Examples of the heteroaryl group include a pyrrole group, an indole group, a carbazole group, a furan group, and a thiophene group, and an indole group is preferable. When the arylsulfonium compound has two or more aryl groups, the two or more aryl groups may be the same or different.

  The alkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, sec- Examples thereof include a butyl group and a t-butyl group.

  The cycloalkyl group that the arylsulfonium compound has as necessary is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.

The aryl group, alkyl group, and cycloalkyl group of R _{201 to} R ₂₀₃ are an alkyl group (for example, having 1 to 15 carbon atoms), a cycloalkyl group (for example, having 3 to 15 carbon atoms), an aryl group (for example, having 6 to 6 carbon atoms). 14), an alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, a phenylthio group or the like may be used as a substituent. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and alkoxy groups having 1 to 12 carbon atoms, more preferably alkyl having 1 to 4 carbon atoms. Group, an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Examples of the organic sulfonate anion of X ⁻ include an aliphatic sulfonate anion, an aromatic sulfonate anion, a camphor sulfonate anion, and the like.

  Examples of the aliphatic group in the aliphatic sulfonate anion include, for example, an alkyl group having 1 to 30 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, sec- Butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl And an eicosyl group and a cycloalkyl group having 3 to 30 carbon atoms, specifically, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornyl group, a boronyl group, and the like.

  The aromatic group in the aromatic sulfonate anion is preferably an aryl group having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, and a naphthyl group.

  The alkyl group, cycloalkyl group, and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion may have a substituent.

  Examples of such substituents include nitro groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), carboxyl groups, hydroxyl groups, amino groups, cyano groups, and alkoxy groups (preferably having 1 to 5 carbon atoms). ), A cycloalkyl group (preferably 3 to 15 carbon atoms), an aryl group (preferably 6 to 14 carbon atoms), an alkoxycarbonyl group (preferably 2 to 7 carbon atoms), an acyl group (preferably 2 to 12 carbon atoms). ), An alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms), an alkylthio group (preferably having 1 to 15 carbon atoms), and the like. About the aryl group and ring structure which each group has, an alkyl group (preferably C1-C15) can further be mentioned as a substituent.

The organic sulfonate anion of X ⁻ is preferably an aliphatic sulfonate anion in which the α-position of the sulfonic acid is substituted with a fluorine atom, or an aromatic sulfonate anion substituted with a fluorine atom or a group having a fluorine atom. The organic sulfonate anion is more preferably a perfluoroaliphatic sulfonate anion having 4 to 8 carbon atoms, an aromatic sulfonate anion having a fluorine atom, particularly preferably nonafluorobutane sulfonate anion, perfluorooctane sulfonate anion, penta Fluorobenzenesulfonate anion, 3,5-bis (trifluoromethyl) benzenesulfonate anion.

Next, the compound (ZI-2) will be described.
The compound (ZI-2) is, R ₂₀₁ to R ₂₀₃ in formula (ZI) each independently is a compound when it represents an organic group having no aromatic ring.

The organic group having no aromatic ring as R ₂₀₁ to R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.

R _{201 to} R ₂₀₃ are each independently preferably an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group, more preferably a linear, branched, cyclic 2-oxoalkyl group, or an alkoxycarbonylmethyl group, particularly preferably Is a linear, branched 2-oxoalkyl group.

The alkyl group as R _{201 to} R ₂₀₃ may be either linear or branched, and is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. Butyl group, pentyl group and the like. More preferable examples of the alkyl group include a linear or branched 2-oxoalkyl group and an alkoxycarbonylmethyl group.

The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is preferably a cycloalkyl group having 3 to 10 carbon atoms, e.g., cyclopentyl, cyclohexyl group and a norbornyl group. More preferable examples of the cycloalkyl group include a cyclic 2-oxoalkyl group.

  The 2-oxoalkyl group may be linear, branched or cyclic, and preferably includes a group having> C═O at the 2-position of the above alkyl group or cycloalkyl group.

  The alkyl group in the alkoxycarbonylmethyl group is preferably an alkyl group having 1 to 5 carbon atoms (methyl group, ethyl group, propyl group, butyl group, pentyl group).

R _{201 to} R ₂₀₃ may be further substituted with a halogen atom, an alkoxy group (eg, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group.

  The compound (ZI-3) is a compound represented by the following general formula (ZI-3), and is a compound having a phenacylsulfonium salt structure.

In general formula (ZI-3),
R _{1c to} R _5c each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group or a halogen atom.
R _6c and R _7c represent a hydrogen atom, an alkyl group, or a cycloalkyl group.
Rx and Ry each independently represents an alkyl group, a cycloalkyl group, an allyl group or a vinyl group.
Any two or more of R _1c to R _7c, and R _x and R _y may be bonded to each other to form a ring structure, the ring structure may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond May be included. Examples of the group formed by combining any two or more of R _{1c to} R _7c and R _x and R _y include a butylene group and a pentylene group.
Zc ⁻ represents an organic sulfonate anion, and examples thereof include the same as the organic sulfonate anion of X ^{− in} formula (ZI).

The alkyl group as R _{1c to} R _7c is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, A linear or branched pentyl group can be exemplified.

The cycloalkyl group as R _{1c to} R _7c is preferably a cycloalkyl group having 3 to 8 carbon atoms, and examples thereof include a cyclopentyl group and a cyclohexyl group.

The alkoxy group as R _{1c to} R _{5c may} be linear, branched or cyclic, for example, an alkoxy group having 1 to 10 carbon atoms, preferably a linear or branched alkoxy group having 1 to 5 carbon atoms. (For example, methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, linear or branched pentoxy group), C3-C8 cyclic alkoxy group (for example, cyclopentyloxy group, cyclohexyloxy group) ).

Preferably, any one of R _{1c to} R _5c is a linear or branched alkyl group, a cycloalkyl group, or a linear, branched or cyclic alkoxy group, and more preferably the sum of the carbon number of R _{1c to} R _5c is 2 ~ 15. Thereby, solvent solubility improves more and generation | occurrence | production of a particle is suppressed at the time of a preservation | save.

Examples of the alkyl group and cycloalkyl group as R _x and R _y include the same as the alkyl group and cycloalkyl group as R _{1c to} R _7c , and a 2-oxoalkyl group and an alkoxycarbonylmethyl group are more preferable. preferable.

Examples of the 2-oxoalkyl group include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group as R _{1c to} R _7c .

Examples of the alkoxy group in the alkoxycarbonylmethyl group include the same alkoxy groups as R _{1c to} R _5c .

R _x and R _y are preferably an alkyl group having 4 or more carbon atoms, more preferably 6 or more, and still more preferably 8 or more.

In general formulas (ZII) and (ZIII),
R ₂₀₄ to R ₂₀₇ each independently represents an aryl group, an alkyl group or a cycloalkyl group.
Examples of the aryl group of R _{204 to} R ₂₀₇ include an aryl group composed of a hydrocarbon and a heteroaryl group having a hetero atom such as a nitrogen atom, a sulfur atom, or an oxygen atom. The aryl group composed of hydrocarbon is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. Examples of the heteroaryl group include a pyrrole group, an indole group, a carbazole group, a furan group, and a thiophene group, and an indole group is preferable.
The alkyl group as R ₂₀₄ to R ₂₀₇ is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group).
The cycloalkyl group as R ₂₀₄ to R ₂₀₇ is preferably a cycloalkyl group having 3 to 10 carbon atoms, e.g., cyclopentyl, cyclohexyl group and a norbornyl group.
The R ₂₀₄ to R ₂₀₇ are substituents which may have, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (e.g., 6 carbon atoms 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.
X ⁻ represents an organic sulfonate anion, and examples thereof include the same organic sulfonate anions as X ^{− in} formula (ZI).

  Preferable examples of the sulfonic acid generator include compounds represented by the following general formulas (ZIV), (ZV), and (ZVI).

In general formulas (ZIV) to (ZVI),
Ar ₃ and Ar ₄ each independently represents an aryl group.
R ₂₀₆ , R ₂₀₇ and R _{208 each} represents an alkyl group, a cycloalkyl group or an aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

  Preferable examples of the sulfonic acid generator include compounds represented by the following general formula (ZVII).

In general formula (ZVII),
R _210a and R _211a each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a cyano group, a nitro group or an alkoxycarbonyl group, preferably a halogen-substituted alkyl group or a cycloalkyl group, a nitro group or a cyano group. is there.
R _212a represents a hydrogen atom, an alkyl group, a cycloalkyl group, a cyano group or an alkoxycarbonyl group.
X _1a represents a monovalent group formed by removing a hydrogen atom of —SO ₃ H of an organic sulfonic acid.

  Preferred examples of the sulfonic acid generator include compounds represented by the following general formula (ZVIII).

In general formula (ZVIII):
Ra represents an alkyl group, a cycloalkyl group, or an aryl group. When there are a plurality of Ras, the plurality of Ras may be the same or different.
n represents an integer of 1 to 6.

  Hereinafter, although the specific example of a sulfonic acid generator is given, this invention is not limited to this.

The content of the sulfonic acid generator is 5 to 20% by mass, preferably 6 to 18% by mass, particularly preferably 7 to 16% by mass, based on the solid content of the positive resist composition. It is 5% by mass or more from the viewpoint of sensitivity and line edge roughness, and 20% by mass or less from the viewpoint of resolution, pattern shape, and film quality. Moreover, one type of sulfonic acid generator may be used, or two or more types may be mixed and used. For example, as the sulfonic acid generator, a compound that generates aryl sulfonic acid upon irradiation with active light or radiation and a compound that generates alkyl sulfonic acid upon irradiation with active light or radiation may be used in combination.
The sulfonic acid generator can be synthesized by a known method such as a synthesis method described in JP-A-2002-27806.

The positive resist composition of the present invention may use, together with a sulfonic acid generator, a compound that generates a carboxylic acid upon irradiation with actinic rays or radiation (hereinafter also referred to as “carboxylic acid generator”).
As the carboxylic acid generator, a compound represented by the following general formula (C) is preferable.

In general formula (C),
R _{21 to} R ₂₃ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group.
R ₂₄ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group.
Z represents a sulfur atom or an iodine atom. When Z is a sulfur atom, p is 1, and when Z is an iodine atom, p is 0.

In the general formula (C), R _{21 to} R ₂₃ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group, and these groups may have a substituent.
Examples of the substituent that the alkyl group, cycloalkyl group or alkenyl group may have include a halogen atom (a chlorine atom, a bromine atom, a fluorine atom, etc.), an aryl group (a phenyl group, a naphthyl group, etc.), a hydroxy group, An alkoxy group (methoxy group, ethoxy group, butoxy group, etc.) etc. can be mentioned.
Examples of the substituent that the aryl group may have include a halogen atom (chlorine atom, bromine atom, fluorine atom, etc.), nitro group, cyano group, alkyl group (methyl group, ethyl group, t-butyl group, t -Amyl group, octyl group, etc.), hydroxy group, alkoxy group (methoxy group, ethoxy group, butoxy group, etc.) and the like.

R _{21 to} R ₂₃ are preferably each independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an aryl group having 6 to 24 carbon atoms. And more preferably an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 18 carbon atoms, and particularly preferably an aryl group having 6 to 15 carbon atoms. Each of these groups may have a substituent.

R ₂₄ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group.
Examples of the substituent that the alkyl group, cycloalkyl group, and alkenyl group may have are the same as those described as examples of the substituent when R ₂₁ is an alkyl group. Examples of the substituent for the aryl group, the R ₂₁ may be the same as those mentioned as examples of the substituent when it is an aryl group.

R ₂₄ is preferably a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 24 carbon atoms, and more Preferably, they are a C1-C18 alkyl group, a C3-C18 cycloalkyl group, and a C6-C18 aryl group, Most preferably, a C1-C12 alkyl group, C3-C3 A cycloalkyl group having 12 carbon atoms and an aryl group having 6 to 15 carbon atoms. Each of these groups may have a substituent.

Z represents a sulfur atom or an iodine atom. p is 1 when Z is a sulfur atom, and 0 when Z is an iodine atom.
In addition, the cation structure which has two or more of the cation part of general formula (C) couple | bonded by the single bond or the coupling group (for example, -S-, -O-, etc.), and has two or more cation parts of general formula (C). May be formed.

  Although the preferable specific example of the compound which generate | occur | produces carboxylic acid by irradiation of actinic light or a radiation below is given, of course, it is not limited to these.

The content of the carboxylic acid generator in the positive resist composition of the present invention is preferably 0.01 to 10% by mass, more preferably 0.03 to 5% by mass, based on the total solid content of the composition. Particularly preferably, it is 0.05 to 3% by mass. In addition, these compounds that generate a carboxylic acid upon irradiation with actinic rays or radiation may be used alone or in combination of two or more.
The carboxylic acid generator / sulfonic acid generator (mass ratio) is usually 99.9 / 0.1 to 50/50, preferably 99/1 to 60/40, and particularly preferably 98/2 to 70/30. .
The carboxylic acid generator can be synthesized by a known method such as the synthesis method described in JP-A-2002-27806.

[4] Basic Compound In the present invention, it is preferable to use a basic compound from the viewpoints of improving performance such as resolution and improving storage stability. As the basic compound, a compound containing a nitrogen atom (nitrogen-containing organic basic compound) is more preferable.
A preferable basic compound in the present invention is a compound having a stronger basicity than phenol.
As a preferable chemical environment, structures of the following formulas (A) to (E) can be exemplified. Formulas (B) to (E) may be part of a ring structure.

In general formula (A),
R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different and each represents a hydrogen atom, an alkyl or cycloalkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, R ²⁰¹ and R ²⁰² may combine with each other to form a ring.
The alkyl group, cycloalkyl group and aryl group as R ²⁰⁰ , R ²⁰¹ and R ²⁰² may have a substituent. As the alkyl group and cycloalkyl group having a substituent, an aminoalkyl group having 1 to 20 carbon atoms and an aminocycloalkyl group, and a hydroxyalkyl group having 1 to 20 carbon atoms are preferable.
In general formula (E),
R ²⁰³ , R ²⁰⁴ , R ²⁰⁵ and R ²⁰⁶ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms and a cycloalkyl group.

  Further preferred compounds are nitrogen-containing organic basic compounds having two or more nitrogen atoms of different chemical environments in one molecule, and particularly preferably both a substituted or unsubstituted amino group and a ring structure containing a nitrogen atom. Or a compound having an alkylamino group.

Preferred examples include guanidine, aminopyridine, aminoalkylpyridine, aminopyrrolidine, indazole, imidazole, pyrazole, pyrazine, pyrimidine, purine, imidazoline, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine and the like. Preferred substituents that these may have include amino groups, alkylamino groups, aminoaryl groups, arylamino groups, alkyl groups (substituent alkyl groups, particularly aminoalkyl groups), alkoxy groups, acyl groups, and acyloxy groups. , Aryl group, aryloxy group, nitro group, hydroxyl group, cyano group and the like.

Particularly preferred compounds include guanidine, 1,1-dimethylguanidine, 1,1,3,3-tetramethylguanidine, imidazole, 2-methylimidazole, 4-methylimidazole, N-methylimidazole, 2-phenylimidazole, 4 , 5-diphenylimidazole, 2,4,5-triphenylimidazole, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2-dimethylaminopyridine, 4-dimethylaminopyridine, 2-diethylaminopyridine, 2- (Aminomethyl) pyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-6-methylpyridine, 3-aminoethylpyridine, 4- Aminoethylpyridine, 3-aminopyrrolidine, Perazine, N- (2-aminoethyl) piperazine, N- (2-aminoethyl) piperidine, 4-amino-2,2,6,6-tetramethylpiperidine, 4-piperidinopiperidine, 2-iminopiperidine, 1- (2-aminoethyl) pyrrolidine, pyrazole, 3-amino-5-methylpyrazole, 5-amino-3-methyl-1-p-tolylpyrazole, pyrazine, 2- (aminomethyl) -5-methylpyrazine, Examples include, but are not limited to, pyrimidine, 2,4-diaminopyrimidine, 4,6-dihydroxypyrimidine, 2-pyrazoline, 3-pyrazoline, N-aminomorpholine, N- (2-aminoethyl) morpholine. It is not a thing.
These nitrogen-containing organic basic compounds are used alone or in combination of two or more.

  Further, a tetraalkylammonium salt type nitrogen-containing basic compound can also be used. Of these, tetraalkylammonium hydroxide having 1 to 8 carbon atoms (tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra- (n-butyl) ammonium hydroxide, etc.) is particularly preferable. These nitrogen-containing basic compounds are used alone or in combination of two or more.

  The use ratio of the acid generator and the basic compound in the composition is preferably (total amount of acid generator) / (basic compound) (molar ratio) = 2.5 to 300. By setting the molar ratio to 2.5 or more, high sensitivity is obtained, and by setting the molar ratio to 300 or less, it is possible to suppress the resist pattern from becoming thicker over time until post-exposure heat treatment and improve resolution. . (Total amount of acid generator) / (basic compound) (molar ratio) is preferably 5.0 to 200, more preferably 7.0 to 150.

[5] Surfactants In the present invention, surfactants can be used, which are preferable from the viewpoints of film-forming properties, pattern adhesion, development defect reduction, and the like.

Specific examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene Polyoxyethylene alkyl allyl ethers such as nonylphenol ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Sorbitan fatty acid esters such as rate, polyoxyethylene sorbitan monolaurate, polyoxyethylene Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as bitane monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, Ftop EF301, EF303, EF352 (manufactured by Shin-Akita Kasei Co., Ltd.), Megafac F171, F173 (manufactured by Dainippon Ink and Chemicals), Florad FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (Asahi Glass Co., Ltd.), Troisol S-366 (Troy Chemical Co., Ltd.) and other fluorine-based surfactants or silicon-based surfactants, organosilanes Hexane polymer KP341 (manufactured by Shin-Etsu Chemical Co.) and acrylic or methacrylic acid-based (co) polymer Polyflow No. 75, no. 95 (manufactured by Kyoeisha Yushi Chemical Co., Ltd.).

The compounding amount of these surfactants is usually 2 parts by mass or less, preferably 1 part by mass or less per 100 parts by mass of the solid content in the composition of the present invention.
These surfactants may be added alone or in some combination.

As the surfactant, any one of fluorine-based and / or silicon-based surfactants (fluorine-based surfactant and silicon-based surfactant, surfactant containing both fluorine atom and silicon atom), or two kinds of surfactants It is preferable to contain the above.
As these surfactants, for example, JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-63-34540 No. 7, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, JP-A 2002-277862, US Pat. No. 5,405,720. , No. 5,360,692, No. 5,529,881, No. 5,296,330, No. 5,543,098, No. 5,576,143, No. 5,294,511, No. 5,824,451. The following commercially available surfactants can also be used as they are.
Examples of commercially available surfactants that can be used include F-top EF301, EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430, 431 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176, F189, R08 (Dainippon Ink Chemical Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troisol S-366 (Troy Chemical Co., Ltd.), etc. Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

In addition to the known surfactants described above, the surfactant is derived from a fluoroaliphatic compound produced by a telomerization method (also called telomer method) or an oligomerization method (also called oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.
As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. Or may be block copolymerized. Examples of the poly (oxyalkylene) group include a poly (oxyethylene) group, a poly (oxypropylene) group, a poly (oxybutylene) group, and the like, and a poly (oxyethylene, oxypropylene, and oxyethylene group). A unit having different chain lengths in the same chain length, such as a block linked body) or a poly (block linked body of oxyethylene and oxypropylene) group, may be used. Furthermore, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate (or methacrylate) is not only a binary copolymer but also a monomer having two or more different fluoroaliphatic groups, Further, it may be a ternary or higher copolymer obtained by simultaneously copolymerizing two or more different (poly (oxyalkylene)) acrylates (or methacrylates).
Examples of commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (Dainippon Ink Chemical Co., Ltd.). Further, a copolymer of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxyalkylene)) acrylate (or methacrylate), an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxy) (Ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate) copolymer, acrylate (or methacrylate) and (poly (oxyalkylene)) acrylate having C ₈ F ₁₇ groups (or Copolymer of acrylate (or methacrylate), (poly (oxyethylene)) acrylate (or methacrylate), and (poly (oxypropylene)) acrylate (or methacrylate) having a C ₈ F ₁₇ group Coalesce, etc. Can.

  The amount of the surfactant used is preferably 0.0001 to 2% by mass, more preferably 0.001 to 1% by mass, based on the total amount of the positive resist composition (excluding the solvent).

[6] Other components The positive resist composition of the present invention may further contain a dye, a photobase generator and the like, if necessary.

1. Dye A dye can be used in the present invention.
Suitable dyes include oily dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (oriental chemical industry) Co., Ltd.), crystal violet (CI42555), methyl violet (CI42535), rhodamine B (CI45170B), malachite green (CI42000), methylene blue (CI522015) and the like.

2. Photobase generator As photobase generators that can be added to the composition of the present invention, JP-A-4-151156, JP-A-4-162040, JP-A-5-197148, JP-A-5-5995, JP-A-6-194835, Examples thereof include compounds described in JP-A-8-146608, JP-A-10-83079 and European Patent No. 622682, specifically, 2-nitrobenzylcarbamate, 2,5-dinitrobenzylcyclohexylcarbamate, N-cyclohexyl-4- Methylphenylsulfonamide, 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate and the like can be suitably used. These photobase generators are added for the purpose of improving the resist shape and the like.

3. Solvents The resist composition of the present invention is dissolved in a solvent that dissolves each of the above components and coated on a support. The solid content concentration of all resist components is usually preferably 2 to 30% by mass, more preferably 3 to 25% by mass.
Solvents used here include ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl ether acetate , Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, N, N-dimethyl Formamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran and the like are preferable. Or mixed to use.

  The positive resist composition of the present invention is applied onto a substrate to form a thin film. The thickness of this coating film is preferably 0.05 to 4.0 μm.

  In the present invention, a commercially available inorganic or organic antireflection film can be used if necessary. Furthermore, an antireflection film can be applied to the resist lower layer and used.

  As the antireflection film used as the lower layer of the resist, either an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, amorphous silicon, or an organic film type made of a light absorber and a polymer material may be used. it can. The former requires equipment such as a vacuum deposition apparatus, a CVD apparatus, and a sputtering apparatus for film formation. Examples of the organic antireflection film include a condensate of a diphenylamine derivative and a formaldehyde-modified melamine resin described in JP-B-7-69611, an alkali-soluble resin, a light absorber, and maleic anhydride copolymer described in US Pat. No. 5,294,680. A reaction product of a coalescence and a diamine type light absorbent, a resin binder described in JP-A-6-186863 and a methylolmelamine thermal crosslinking agent, a carboxylic acid group, an epoxy group and a light-absorbing group described in JP-A-6-118656. An acrylic resin-type antireflection film in the same molecule, a composition comprising methylol melamine and a benzophenone-based light absorber described in JP-A-8-87115, and a low-molecular light absorber added to a polyvinyl alcohol resin described in JP-A-8-179509. And the like.

  In addition, as the organic antireflection film, commercially available organic antireflection films such as DUV30 series, DUV-40 series manufactured by Brewer Science, and AR-2, AR-3, AR-5 manufactured by Shipley may be used. it can.

  In the manufacture of precision integrated circuit elements, the pattern forming process on the resist film is carried out on the substrate (eg, silicon / silicon dioxide coated substrate, glass substrate, ITO substrate, quartz / chromium oxide coated substrate, etc.). A resist pattern is formed by applying a resist composition, forming a resist film, and then irradiating actinic rays or radiation such as KrF excimer laser light, electron beam, EUV light, etc., heating, developing, rinsing and drying. Can be formed.

Examples of the alkaline developer used in development include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, and primary amines such as ethylamine and n-propylamine. Secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcoholamines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, An aqueous solution (usually 0.1 to 20% by mass) of an alkali such as a quaternary ammonium salt such as choline or a cyclic amine such as pyrrole or piperidine can be used. Furthermore, an appropriate amount of an alcohol such as isopropyl alcohol or a nonionic surfactant may be added to the alkaline aqueous solution.
Among these developers, quaternary ammonium salts are preferable, and tetramethylammonium hydroxide and choline are more preferable.
The pH of the alkali developer is usually 10-15.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the content of this invention is not limited by this.

Synthesis Example 1 (Synthesis of Resin (1))
Acetoxystyrene, styrene, 2-methyl-2-adamantyl cinnamate 60 /
It was charged at a ratio (molar ratio) of 20/20 and dissolved in tetrahydrofuran to prepare 100 mL of a solution having a solid content concentration of 20% by mass. To this solution was added 2 mol% of a polymerization initiator V-65 manufactured by Wako Pure Chemical Industries, Ltd., and this was added dropwise to 10 mL of tetrahydrofuran heated to 60 ° C. over 4 hours in a nitrogen atmosphere. After completion of dropping, the reaction solution was heated for 4 hours, 1 mol% of V-65 was added again, and the mixture was stirred for 4 hours. After completion of the reaction, the reaction solution was cooled to room temperature, crystallized in 3 L of hexane, and the precipitated white powder was collected by filtration.
The composition ratio of the polymer determined from C ¹³ NMR was 58/20/22 (molar ratio). Moreover, the weight average molecular weight of standard polystyrene conversion calculated | required by GPC measurement was 9,500.
This polymer was dissolved in 100 ml of acetone, 5 ml of hydrochloric acid was added and stirred for 1 hour, and distilled water was added to precipitate the polymer. The precipitate was washed with distilled water and then dried under reduced pressure. After dissolving the polymer in 100 ml of ethyl acetate, hexane was added and the precipitated polymer was powdered by drying under reduced pressure. The weight average molecular weight in terms of standard polystyrene determined by GPC measurement for this powder was 10,000.

  Resins (1) to (8), (10) to (12) and (14) whose structures were previously exemplified, shown in Table 1, were synthesized in the same manner as in Synthesis Example 1. The molar ratio of the repeating units in Table 1 is the order from the left of the repeating units in the structure shown above.

  The resin (A1), the resin (A2) and the acid generator were all synthesized by a known synthesis method such as the synthesis method described in JP-A-2002-27806.

  Table 2 below shows the repeating unit (mol%), weight average molecular weight, and dispersity of the resin (A1) used in the examples. The molar ratio of the repeating units in Table 2 is the order from the left of the repeating units in the structure shown above.

  Table 3 below shows the repeating unit (mol%), weight average molecular weight, and dispersity of the resin (A2) used in the examples. The molar ratio of the repeating units in Table 3 is the order from the left of the repeating units in the structure shown above.

Example 1
(1) Preparation and coating of positive resist Resin (1) 0.63 g
Resin (PI-2) 0.30g
0.07 g of acid generator (B-2)
Is dissolved in 8.8 g of propylene glycol monomethyl ether acetate, 0.001 g of D-1 (see below) as a basic compound, and MegaFac F176 (manufactured by Dainippon Ink & Chemicals, Inc.) as a surfactant, 0.001 g) (abbreviated as “W-1”) was added and dissolved, and the resulting solution was microfiltered with a 0.1 μm aperture membrane filter to obtain a resist solution.
This resist solution was applied onto a 6-inch silicon wafer using a spin coater Mark8 manufactured by Tokyo Electron, and baked at 110 ° C. for 90 seconds to obtain a uniform film having a thickness of 0.25 μm.

(2) Formation and Evaluation of Positive Resist Pattern This resist film was irradiated with an electron beam using an electron beam drawing apparatus (HL750 manufactured by Hitachi, Ltd., acceleration voltage 50 KeV). After irradiation, it was baked at 110 ° C. for 90 seconds, immersed in an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 60 seconds, rinsed with water for 30 seconds and dried. The obtained pattern was evaluated by the following method.

(2-1) Sensitivity The cross-sectional shape of the obtained pattern was observed using a scanning electron microscope (S-4300, manufactured by Hitachi, Ltd.). The minimum irradiation energy when resolving a 0.15 μm line (line: space = 1: 1) was defined as sensitivity.
(2-2) LWR (Line Edge Roughness)
About the resist pattern obtained by carrying out similarly to the above, the line width was observed with the scanning electron microscope (S-9220 by Hitachi, Ltd.), and the fluctuation | variation (LWR) of the line width in the line width of 130 nm was observed. Using a length-measuring scanning electron microscope (SEM), the line width was detected at a plurality of positions in the measurement monitor, and the dispersion (3σ) of variations in the detected positions was used as an LWR index.
(2-3) Dense / Dense Dependence The line width of the dense pattern (line: space = 1: 1) and the line width of the isolated pattern in the 0.15 μm line pattern at the irradiation dose showing the above sensitivity are measured, and the difference between them is measured. Sparse and dense dependence.

As a result of Example 1, the sensitivity was 10.0 μC / cm ² , the LWR was 6.5, and the density dependence was 11 nm, which was very good.

Examples 2 to 7 and Comparative Example 1
Using the compounds shown in Table 4 below, resist preparation / coating and electron beam exposure evaluation were carried out in the same manner as in Example 1. The evaluation results are shown in Table 4.

Hereinafter, abbreviations in the table are shown.
[Basic compounds]
D-1: tri-n-hexylamine D-2: 2,4,6-triphenylimidazole D-3: tetra- (n-butyl) ammonium hydroxide [surfactant]
W-1: Fluorosurfactant (Megafac F-176, manufactured by Dainippon Ink & Chemicals, Inc.)
W-2: Fluorine / silicone surfactant (Megafac R08, manufactured by Dainippon Ink & Chemicals, Inc.)
W-3: Silicone surfactant (siloxane polymer KP341, manufactured by Shin-Etsu Chemical Co., Ltd.)

  From Table 4, it can be seen that the positive resist composition of the present invention is higher in sensitivity than the compound of the comparative example, and is excellent in line edge roughness and density dependence, with respect to pattern formation by electron beam irradiation. .

Example 8
In the same manner as in Example 1, a resist was prepared and coated with the formulation shown in Table 5 below to obtain a resist film. However, the film thickness was 0.40 μm.

(3) Formation and Evaluation of Positive Pattern The obtained resist film was subjected to pattern exposure using a KrF excimer laser stepper (FPA3000EX-5 manufactured by Canon Inc., wavelength 248 nm). The post-exposure processing was performed in the same manner as in Example 1. The pattern was evaluated as follows.
(3-1) Sensitivity The cross-sectional shape of the obtained pattern was observed using a scanning electron microscope (S-4300, manufactured by Hitachi, Ltd.). The minimum irradiation energy when resolving a 0.18 μm line (line: space = 1: 1) was defined as sensitivity.
(3-2) LWR (Line Edge Roughness)
About the resist pattern obtained by carrying out similarly to the above, the line width was observed with the scanning electron microscope (S-9220 by Hitachi, Ltd.), and the fluctuation | variation (LWR) of the line width in the line width of 130 nm was observed. Using a length-measuring scanning electron microscope (SEM), the line width was detected at a plurality of positions in the measurement monitor, and the dispersion (3σ) of variations in the detected positions was used as an LWR index.
(3-3) Density dependency The line width of the dense pattern (line: space = 1: 1) and the line width of the isolated pattern in the 0.18 μm line pattern at the irradiation dose exhibiting the above sensitivity are measured, and the difference between them is measured. Sparse and dense dependence.

As a result of Example 8, the sensitivity was 10 mJ / cm ² , the LWR was 6.8, and the density dependency was 12 nm.

Examples 9 to 14 and Comparative Example 2
Using the compounds shown in Table 5 below, resist preparation / coating and KrF excimer laser exposure evaluation were performed in the same manner as in Example 8. The evaluation results are shown in Table 5.

  From Table 5, it can be seen that the positive resist composition of the present invention is higher in sensitivity than the compound of the comparative example and has excellent line edge roughness and density dependency with respect to pattern formation by KrF excimer laser exposure. .

Examples 15 to 19 and Comparative Example 3
With the formulation shown in Table 6 below, resist preparation and coating were performed in the same manner as in Example 1 to obtain a resist film. However, the resist film thickness was 0.13 μm. The obtained resist film was subjected to surface exposure using EUV light (wavelength 13 nm) while changing the exposure amount by 0.5 mJ in the range of 0 to 5.0 mJ, and further baked at 110 ° C. for 90 seconds. Thereafter, using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution, the dissolution rate at each exposure amount was measured to obtain a sensitivity curve. In this sensitivity curve, the exposure amount when the dissolution rate of the resist is saturated was taken as sensitivity, and the dissolution contrast (γ value) was calculated from the gradient of the linear portion of the sensitivity curve. The larger the γ value, the better the dissolution contrast.
The results are shown in Table 6.

  From Table 4, it can be seen that the positive resist composition of the present invention is superior in sensitivity and high contrast as compared with the composition of the comparative example in the property evaluation by irradiation with EUV light.

Claims (6)

(A) a compound that generates an acid upon irradiation with an actinic ray or radiation,
(B) The solubility in an alkali developer is increased by the action of a resin having a repeating unit represented by the following general formula (I) and (C) an acid having a repeating unit represented by the following general formula (A1). And at least one resin selected from resins whose solubility in an alkaline developer is increased by the action of an acid having a repeating unit represented by the following general formula (A2): Resist composition.

In general formula (I),
Ra represents a hydrogen atom or an organic group.
Rb represents a hydrogen atom or an organic group.
n represents an integer of 0 to 2.
In general formula (A1),
A ₁ represents a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid.
In general formula (A2),
A ₂ represents a group having a group capable of leaving by the action of an acid or a group decomposing by the action of an acid.
X represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or an alkyloxycarbonyl group.   2. The positive resist composition according to claim 1, wherein at least one of Ra and Rb in the general formula (I) is a group capable of leaving by the action of an acid. In general formula (A2), a group in A ₂ that is eliminated by the action of an acid, or a group that is eliminated by the action of an acid in a group that is decomposed by the action of an acid (acid-decomposable group), 2. The positive resist composition according to claim 1, which has a cyclic carbon structure. In the general formula (A1), a group in A ₁ that is eliminated by the action of an acid, or a group that is eliminated by the action of an acid in a group that is decomposed by the action of an acid (acid-decomposable group), 2. The positive resist composition according to claim 1, which has a cyclic carbon structure.   3. The positive type according to claim 2, wherein in general formula (I), at least one of groups leaving by the action of an acid in Ra and Rb has a cyclic carbon structure. Resist composition.   A pattern forming method comprising: forming a resist film with the positive resist composition according to claim 1, exposing and developing the resist film.