JP4691461B2 - Positive resist composition and pattern forming method using the same - Google Patents

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. More specifically, the present invention relates to a positive photoresist capable of forming a high-definition pattern using KrF excimer laser light, electron beam, EUV light, etc., and a semiconductor device using KrF excimer laser light, electron beam, EUV light The present invention relates to a positive resist composition that can be suitably used for microfabrication and a pattern formation method using the same.

  Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a photoresist 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. Along with this, there is a tendency to shorten the exposure wavelength 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 forming technology, and a positive resist with high sensitivity and high resolution 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 to be pursued, not only the resolution will be lowered. The development of resists that 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, high resolution, good pattern shape, and good density dependence are in a trade-off relationship, and how to satisfy them simultaneously is very important.

Furthermore, in lithography using KrF excimer laser light, it is also important to satisfy high sensitivity, high resolution, good pattern shape, and good density dependency at the same time. is there.
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, the current situation is that high sensitivity, high resolution, good pattern shape, and good density dependence are not satisfied at the same time in the ultrafine region.

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 high resolution. It is an object of the present invention to provide a positive resist composition in which properties, roughness and density dependency are suppressed, and the dissolution contrast is good, and a pattern forming method using the same.

一般式（Ａ１）及び（Ａ２）において、Ｘは、水素原子、アルキル基、ハロゲン原子、シアノ基またはアルキルオキシカルボニル基を示す。
Ａ ₁ は水素原子、または、酸の作用により分解する基若しくは酸の作用により分解する基を含む基を表す。
Ｓ ₁ は１価の置換基を表す。
ｍ及びｎは、各々０〜３の整数を表す。但し、ｍ＋ｎ≦５である。
Ａ ₂ は、酸の作用により分解する基又は酸の作用により分解する基を含む基を表す。

Ｒ ₁ は、水素原子、メチル基、シアノ基又はハロゲン原子を表す。
Ｒ ₂ は、アルキル基、ハロゲン原子、アリール基、アルコキシ基又はアシル基を表す。
Ｒ ₃ 及びＲ ₄ は、各々独立に、水素原子又は炭素数１〜４のアルキル基を表す。
Ｚａは、脂環式、芳香環式、有橋脂環式から選ばれる少なくとも１つの環状構造単位を有する炭素数６〜３０の炭化水素基を表す。
ｎは、０〜４の整数を表す。
＜２＞ Ｚａが、芳香環式の環状構造単位を有する炭素数６〜３０の炭化水素基を表すことを特徴とする上記＜１＞に記載のポジ型レジスト組成物。
＜３＞ 樹脂（Ａ）が有する該架橋基に含まれる芳香環の数が２〜８であることを特徴とする上記＜１＞または＜２＞に記載のポジ型レジスト組成物。
＜４＞ 樹脂（Ａ）において、該架橋基に含まれる酸の作用により分解する基が−Ｏ−Ｃ−Ｏ―結合（アセタール結合）であることを特徴とする上記＜１＞〜＜３＞のいずれか一項に記載のポジ型レジスト組成物。
＜５＞ 樹脂（Ａ）において、該架橋基に含まれる酸の作用により分解する基がエステル結合であることを特徴とする上記＜１＞〜＜３＞のいずれか一項に記載のポジ型レジスト組成物。
＜６＞ 上記＜１＞〜＜５＞のいずれか一項に記載のポジ型レジスト組成物により、レジスト膜を形成し、露光、現像する工程を有することを特徴とするパターン形成方法。
本発明は、上記＜１＞〜＜６＞に係る発明であるが、以下、他の事項も含めて記載している。 As a result of intensive studies, it has been found that the above problems can be achieved by the following configuration.
<1> A positive resist composition containing (A) a resin that is soluble in an organic solvent and has increased solubility in an alkali developer by the action of an acid, and (B) a compound that generates an acid upon irradiation with actinic rays or radiation. A thing,
The resin (A) has a structure crosslinked by a crosslinking group, and the crosslinking group has an aromatic ring and an acid-decomposable group that decomposes by the action of an acid to generate an alkali-soluble group.
The resin (A) contains a repeating unit represented by the following general formula (A1) or (A2) and a repeating unit represented by the following general formula (A3), and the crosslinking group is represented by the following general formula (A1) Or a positive resist composition characterized by being linked to a repeating unit represented by (A2) and not linked to a repeating unit represented by the following general formula (A3).

In the general formulas (A1) and (A2), X represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or an alkyloxycarbonyl group.
A ₁ represents a hydrogen atom or a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.
S ₁ represents a monovalent substituent.
m and n each represents an integer of 0 to 3. However, m + n ≦ 5.
A ₂ represents a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.

R ₁ represents a hydrogen atom, a methyl group, a cyano group or a halogen atom.
R ₂ represents an alkyl group, a halogen atom, an aryl group, an alkoxy group or an acyl group.
R ₃ and R ₄ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
Za represents a C6-C30 hydrocarbon group having at least one cyclic structural unit selected from alicyclic, aromatic, and bridged alicyclic.
n represents an integer of 0 to 4.
<2> The positive resist composition as described in <1> above, wherein Za represents a hydrocarbon group having 6 to 30 carbon atoms having an aromatic cyclic structural unit.
<3> The positive resist composition as described in <1> or <2> above, wherein the number of aromatic rings contained in the crosslinking group of the resin (A) is 2 to 8.
<4> In the resin (A), the group that decomposes by the action of an acid contained in the crosslinking group is an —O—C—O— bond (acetal bond). <1> to <3> The positive resist composition as described in any one of the above.
<5> The positive type as described in any one of <1> to <3> above, wherein in the resin (A), the group decomposed by the action of an acid contained in the crosslinking group is an ester bond. Resist composition.
<6> A pattern forming method comprising a step of forming a resist film by using the positive resist composition according to any one of <1> to <5>, exposing and developing the resist film.
Although this invention is invention which concerns on said <1>-<6>, hereafter, other matters are also described.

(1) A positive resist composition containing (A) a resin that is soluble in an organic solvent and has increased solubility in an alkali developer by the action of an acid, and (B) a compound that generates an acid upon irradiation with actinic rays or radiation. A thing,
The resin (A) has a structure crosslinked with a crosslinking group, and the crosslinking group has an aromatic ring and an acid-decomposable group that decomposes by the action of an acid to generate an alkali-soluble group. A positive resist composition.

(2) The positive resist composition as described in (1) above, wherein the resin (A) is a resin containing a repeating unit represented by the general formula (A1) or (A2).

In the general formulas (A1) and (A2), X represents a hydrogen atom, an alkyl group (as a substituted alkyl group, particularly a CF ₃ group, an alkyloxycarbonylmethyl group, an alkylcarbonyloxymethyl group, a hydroxymethyl group, an alkoxymethyl group), A halogen atom, a cyano group or an alkyloxycarbonyl group is shown.

A ₁ represents a hydrogen atom or a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.
S ₁ represents a monovalent substituent.
m and n each represents an integer of 0 to 3. However, m + n ≦ 5.
A ₂ represents a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.

(3) The positive resist composition as described in (1) or (2) above, wherein the number of aromatic rings contained in the crosslinking group of the resin (A) is 2 to 8.
(4) In the resin (A), the group decomposed by the action of an acid contained in the crosslinking group is an —O—C—O— bond (acetal bond). The positive resist composition according to any one of the above.
(5) The positive resist composition as described in any one of (1) to (3) above, wherein the group decomposed by the action of an acid contained in the crosslinking group in the resin (A) is an ester bond object.
(6) A pattern forming method comprising a step of forming a resist film, exposing and developing the positive resist composition according to any one of (1) to (5) above.

  According to the present invention, a positive resist composition excellent in sensitivity, roughness, density dependence, and dissolution contrast with respect to pattern formation by irradiation with an electron beam, KrF excimer laser light, EUV light, or the like, and the same are used. A pattern forming method 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] (A) Resin that is soluble in an organic solvent and is crosslinked by a crosslinking group that is decomposed by the action of an acid to increase solubility in an alkali developer (hereinafter also referred to as resin (A))
The positive resist composition of the present invention has a structure in which the resin is crosslinked by a crosslinking group as a resin (acid-decomposable resin) that is soluble in an organic solvent and has increased solubility in an alkaline developer by the action of an acid. And a crosslinking group having an aromatic ring and a resin having an acid-decomposable group that is decomposed by the action of an acid to generate an alkali-soluble group.
Here, “soluble in an organic solvent” means that the resin exists in a state dissolved in a solvent even though it has a crosslinked structure.

The crosslinkable group possessed by the resin (A) is a group containing an aromatic ring and connecting between the side chains of two polymers, and is formed between at least one polymer side chain and the crosslinkable group or inside the crosslinkable group by the action of an acid. Then, it decomposes to produce an alkali-soluble group such as a carboxyl group or a hydroxyl group in at least one residue after decomposition of the polymer side chain or crosslinking group.
Examples of such a crosslinking group include those having a group having an aromatic ring as a linking group of these bonds formed on the polymer side chain, forming an acid-decomposable ester bond or acetal bond with the polymer side chain. It is done.

  When the resin (A) contains a repeating unit represented by the general formula (A1) as a repeating unit, the crosslinking group is preferably linked to the repeating unit represented by the general formula (A1). It is particularly preferable that the structure represented by the general formula (I) is formed.

In general formula (I), L < ₁ > -L < ₂ > may be same or different and represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aralkyl group.
Z represents a divalent linking group having an aromatic ring.

Examples of the aromatic ring contained in the divalent linking group as Z include a benzene ring, a naphthalene ring, and an anthracene ring, and may be a heterocyclic ring such as a furan ring and a thiophene ring.
The number of aromatic rings in the divalent linking group as Z is preferably 2 to 8, more preferably 2 to 5, and still more preferably 3 to 4.
The divalent linking group as Z may be a divalent group (arylene group) of the aromatic ring itself or a combination with other divalent groups such as an alkylene group.
Carbon number of the bivalent coupling group as Z becomes like this. Preferably it is 12-50, More preferably, it is 12-32, More preferably, it is 18-26.

As L _{1 to} L ₂ , an alkyl group and a cycloalkyl group are a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a pentyl group, a cyclopentyl group, a hexyl group, and a cyclohexyl group. , An octyl group, a dodecyl group, etc., a C1-C20 linear or branched alkyl group, and a cycloalkyl group are mentioned. These groups may have a substituent.

As preferred substituents that the alkyl group and cycloalkyl group as L _{1 to} L ₂ may have, an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a nitro group, an acyl group, an acyloxy group, an acylamino group, a sulfonylamino group, Examples include an alkylthio group, an arylthio group, an aralkylthio group, a thiophenecarbonyloxy group, a thiophenemethylcarbonyloxy group, a heterocyclic residue such as a pyrrolidone residue, and preferably 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 as L _{1 to} L ₂ include those having 7 to 15 carbon atoms such as benzyl group and phenethyl group. These groups may have a substituent.

Preferred substituents that the aralkyl group as L _{1 to} L ₂ may have 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, and an aralkylthio group. Examples of the aralkyl group having a substituent include an alkoxybenzyl group, a hydroxybenzyl group, and a phenylthiophenethyl group. The range of the carbon number of the substituent that the aralkyl group as L _{1 to} L ₂ may have is preferably 12 or less.

  Specific examples of the structure in which the crosslinking group connects the repeating units represented by the general formula (A1) are shown below, but are not limited thereto.

  When the resin (A) contains a repeating unit represented by the general formula (A2) as a repeating unit, the crosslinking group is preferably linked to the repeating unit represented by the general formula (A2). It is particularly preferable to form a structure represented by the formula (II).

L _{3 to} L ₄ may be the same or different and each represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aralkyl group.
Z represents a divalent linking group having an aromatic ring.

L ₃ , L ₄ and Z are the same as the definitions of L ₁ , L ₂ and Z in the general formula (I), respectively.

  Specific examples of the structure in which the cross-linking group connects the repeating units represented by the general formula (A2) are shown below, but are not limited thereto.

  When the resin (A) contains both the repeating unit represented by the general formula (A1) and the repeating unit represented by the general formula (A2) as the repeating unit, the crosslinking group is linked to any repeating unit. May be.

  It is preferable that resin (A) contains the repeating unit shown by General formula (A1) or (A2) which is not connected by the crosslinking group with the repeating unit connected by the crosslinking group.

In the general formulas (A1) and (A2), X represents a hydrogen atom or an alkyl group (preferably a substituted alkyl group, particularly a CF ₃ group, an alkyloxycarbonylmethyl group, an alkylcarbonyloxymethyl group, a hydroxymethyl group, or an alkoxymethyl group. A halogen atom, a cyano group or an alkyloxycarbonyl group, including a substituent, preferably having 5 or less carbon atoms.

A ₁ represents a hydrogen atom or a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.
S ₁ represents a monovalent substituent.
m and n each represents an integer of 0 to 3. However, m + n ≦ 5.

A ₂ represents a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.

In the general formula (A1), the group capable of decomposing by the action of an acid as A ₁ is, for example, a tertiary alkyl group such as t-butyl group or t-amyl group, t-butoxycarbonyl group, isoboronyl group, 1- 1-alkoxyethyl group such as butoxyethyl group, 1-isobutoxyethyl group, 1-cyclohexyloxyethyl group, alkoxymethyl group, tetrahydropyranyl group, tetrahydrofuranyl group, 3-oxocyclohexyl ester group, 2-methyl-2 -An adamantyl group, a mevalonic lactone residue and the like can be mentioned, and those having an alicyclic structure are preferable. In addition, a group represented by —C (R ₃ ) (R ₄ ) —OZa in the following general formula (A3) is also preferable.
Examples of the group containing a group capable of decomposing by the action of an acid of A ₁ include an alkyl group having a —C (═O) —O-acid-decomposable group or —O-acid-decomposable group as a substituent. be able to.

Examples of the monovalent substituent of S ₁ include an alkyl group, an alkoxy group, an acyl group, an acyloxy group, an aryl group, an aryloxy group, an aralkyl group, an aralkyloxy group, a hydroxy group, a halogen atom, a cyano group, and a nitro group. , A sulfonylamino group, an alkylthio group, an arylthio group, and an aralkylthio group. When m is 2 or more, S ₁ may be the same or different.

  Examples of the repeating unit represented by the general formula (A1) include a repeating unit represented by the general formula (A3).

R ₁ represents a hydrogen atom, a methyl group, a cyano group or a halogen atom.
R ₂ represents an alkyl group, a halogen atom, an aryl group, an alkoxy group or an acyl group.
R ₃ and R ₄ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
Za represents a C6-C30 hydrocarbon group having at least one cyclic structural unit selected from alicyclic, aromatic, and bridged alicyclic.
n represents an integer of 0 to 4.

In General Formula (A3), R ₁ represents a hydrogen atom, a methyl group, a cyano group, or a halogen atom. R ₁ is preferably a hydrogen atom, a methyl group, or a C _m F _{2m + 1} group (m is preferably 1), and particularly preferably a hydrogen atom or a methyl group.

The alkyl group as R ₂ is, for example, an alkyl group having 1 to 8 carbon atoms, specifically, methyl group, ethyl group, propyl group, n-butyl group, sec-butyl group, hexyl group, octyl group. Preference is given to groups.
The alkoxy group as R ₂ is, for example, the above alkoxy group having 1 to 8 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, and a cyclohexyloxy group. it can.

The aryl group as R ₂ is, for example, an aryl group having 6 to 15 carbon atoms, and specific examples include a phenyl group, a tolyl group, a naphthyl group, an anthryl group and the like.

The acyl group as R ₂ is, for example, an acyl group having 2 to 8 carbon atoms, and specifically, a formyl group, an acetyl group, a propanoyl group, a butanoyl group, a pivaloyl group, a benzoyl group, and the like are preferably exemplified. it can.

Examples of the alkyl group having 1 to 4 carbon atoms as R ₃ and R ₄ include a methyl group, an ethyl group, and a propyl group.

  The substituents that these groups may have include hydroxyl group, carboxyl group, halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), alkoxy group (methoxy group, ethoxy group, propoxy group, butoxy group) Etc.).

Za represents an acid-decomposable group having at least one cyclic structure selected from alicyclic, aromatic, and bridged alicyclic, but has a structure containing an aromatic group (particularly a phenyl group), or the following general formula A structure containing an alicyclic or bridged alicyclic structure represented by (pI) to (pVI) is preferable.
Za is formed by a bond between at least one cyclic structure selected from alicyclic, aromatic and bridged alicyclic and an alkylene group (preferably having 1 to 5 carbon atoms) directly or via an oxygen atom. It is preferable.

In the formula, R ₁₁ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a sec-butyl group, and Z forms an alicyclic hydrocarbon group together with a carbon atom. Represents the atomic group necessary to do.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group, provided that at least one of R _{12 to} R ₁₄ , or R Either ₁₅ or R ₁₆ represents an alicyclic hydrocarbon group.
R _{17 to} R ₂₁ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group, provided that at least one of R _{17 to} R ₂₁ Represents an alicyclic hydrocarbon group. Further, either R ₁₉ or R ₂₁ represents a linear or branched alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group, provided that at least one of R _{22 to} R ₂₅ Represents 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 _{12 to} R ₂₅ represents a linear or branched alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group 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.
In addition, examples of the substituent that the alkyl group may have include an alkoxy group having 1 to 4 carbon atoms, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), an acyl group, an acyloxy group, and a cyano group. , Hydroxyl group, carboxy group, alkoxycarbonyl group, nitro group and the like.

The alicyclic hydrocarbon group in R _{11 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. Examples of the substituent for the alkyl group and alkoxy group include a hydroxyl group, a halogen atom, and an alkoxy group.

  Specific examples of the repeating unit having a group represented by the general formula (A1) are shown below, but are not limited thereto.

In general formula (A2),
A ₂ represents an acid-decomposable group or a group containing an acid-decomposable group.
X represents a hydrogen atom, an alkyl group (as a substituted alkyl group, particularly a CF ₃ group, an alkyloxycarbonylmethyl group, an alkylcarbonyloxymethyl group, a hydroxymethyl group, an alkoxymethyl group), a halogen atom, a cyano group, or an alkyloxycarbonyl group. Indicates.
Examples of the acid-decomposable group as A ₂ include the same groups as the acid-decomposable group as A ₁ , and the groups represented by the general formulas (pI) to (pVI) are more preferable and preferred groups. Is the same.

Examples of the group containing a group capable of decomposing by the action of an acid of A ₂ include an alkyl group having a —C (═O) —O-acid-decomposable group or —O-acid-decomposable group as a substituent. be able to.

  Hereinafter, although the specific example of the repeating unit represented by general formula (A2) is shown, it is not limited to these.

  The resin (B) preferably contains a hydroxystyrene repeating unit in addition to the above repeating unit. Examples thereof include parahydroxystyrene and metahydroxystyrene, and the benzene ring they have may have a substituent (preferably having 5 or less carbon atoms) such as an alkyl group and an alkoxy group.

  Specific examples of the resin (A) are shown below, but are not limited thereto.

The content of the repeating unit having a crosslinking group in the resin (A) is generally 2 to 15 mol%, preferably 5 to 10 mol%, in all repeating units.
The content of the repeating unit represented by the general formula (A1) in the resin (A) is generally 5 to 40 mol%, preferably 10 to 30 mol%, in all repeating units.
The content of the repeating unit represented by the general formula (A2) in the resin (A) is generally 5 to 35 mol%, preferably 10 to 25 mol%, in all repeating units.
The content of the hydroxystyrene repeating unit in the resin (A) is generally 50 to 90 mol%, preferably 60 to 85 mol%, in all repeating units.

  The resin (A) is copolymerized with other polymerizable monomers suitable so that an alkali-soluble group such as a phenolic hydroxyl group or a carboxyl group can be introduced in order to maintain good developability for an alkali developer. In order to improve the film quality, other hydrophobic polymerizable monomers such as alkyl acrylate and alkyl methacrylate may be copolymerized.

  Resin (A) is, 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, and the like under a nitrogen atmosphere heating condition, After adding a peroxide-based or azo-based radical polymerization initiator and reacting with stirring to polymerize, reprecipitate the polymer such as hexane or methanol in a poor solvent, and filter to powder. It can be synthesized by re-dissolving in an organic solvent such as THF and then reacting with a crosslinking agent such as an aromatic ring-containing divinyl ether. In addition, it is preferable to use a dropping polymerization method in which a monomer dissolved in the solvent and an initiator are added together or separately into the polymerization reaction solution.

The weight average molecular weight (Mw) of the resin (A) is preferably in the range of 1,000 to 15,000, more preferably in the range of 3,000 to 10,000. The dispersity (Mw / Mn) is preferably 1.0 to 2.0, more preferably 1.0 to 1.8, and particularly preferably 1.0 to 1.5.
Here, the weight average molecular weight is defined by a polystyrene conversion value of gel permeation chromatography.

Moreover, you may use resin (A) in combination of 2 or more types.
The total amount of the resin (A) added is generally 10 to 96% by mass, preferably 15 to 96% by mass, and particularly preferably 20 to 95% by mass with respect to the total solid content of the positive resist composition. %.

[2] Compound that generates acid upon irradiation with actinic ray or radiation In the resist composition of the present invention, a known compound may be used as a compound (acid generator) that generates acid upon irradiation with actinic ray or radiation. However, it is preferable to contain a compound that generates sulfonic acid upon irradiation with actinic rays or radiation (sulfonic acid generator) and / or a compound that generates carboxylic acid upon irradiation with actinic rays or radiation (carboxylic acid generator). .

<Compound (B) that generates sulfonic acid upon irradiation with actinic ray or radiation>
The compound that generates sulfonic acid upon irradiation with actinic rays or radiation contained in the resist composition of the present invention (also referred to as compound (B) or sulfonic acid generator) is an actinic ray such as KrF excimer laser light, electron beam, EUV, etc. Or a compound that generates sulfonic acid upon irradiation with radiation, and examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates. .

Further, a group that generates an acid upon irradiation with these actinic rays or radiation, or a compound in which a 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.

Furthermore, compounds capable of generating an 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.
Among these, examples of particularly preferable ones are listed below.

Although content of a compound (B) is used at 5-20 mass% on the basis of the total solid of a resist composition, Preferably it is 6-18 mass%, Most preferably, it is 7-16 mass%. 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, 1 type may be used for a compound (B), and 2 or more types may be mixed and used for it. For example, as the compound (B), a compound that generates aryl sulfonic acid upon irradiation with actinic rays or radiation and a compound that generates alkyl sulfonic acid upon irradiation with actinic rays or radiation may be used in combination.
Compound (B) can be synthesized by a known method such as the synthesis method described in JP-A-2002-27806.

<Compound capable of generating carboxylic acid upon irradiation with actinic ray or radiation (C)>
As the carboxylic acid generator, a compound represented by the following general formula (C) is preferable.
The positive resist composition of the present invention includes a compound (also referred to as a compound (C) or a carboxylic acid generator) that generates a carboxylic acid upon irradiation with actinic rays or radiation together with a sulfonic acid generator (compound (B)). It is preferable to use it.

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 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.
Two or more cation moieties of formula (C) are bonded by a single bond or a linking group (for example, -S-, -O-, etc.) to form a cation structure having a plurality of cation moieties of formula (C). May be.

  The preferred specific examples of the compound (C) that generates a carboxylic acid upon irradiation with actinic rays or radiation are shown below, but of course not limited thereto.

The content of the compound (C) 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, the content 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 compound (C) / compound (B) (mass ratio) is usually 99.9 / 0.1 to 50/50, preferably 99/1 to 60/40, particularly preferably 98/2 to 70/30. .
Compound (C) can be synthesized by a known method such as a synthesis method described in JP-A-2002-27806.

[3] Organic Basic Compound In the present invention, it is preferable to use an organic basic compound from the viewpoint of improving performance such as resolution and improving storage stability. As the organic basic compound, a compound containing a nitrogen atom (nitrogen-containing basic compound) is more preferable.
A preferable organic 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 the formula (A), R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different, and are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group, or an aryl group having 6 to 20 carbon atoms. Here, 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 are
It 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 the 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 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, piperazine, 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)- Examples include 5-methylpyrazine, pyrimidine, 2,4-diaminopyrimidine, 4,6-dihydroxypyrimidine, 2-pyrazoline, 3-pyrazoline, N-aminomorpholine, N- (2-aminoethyl) morpholine. It is not limited to this.
These nitrogen-containing basic compounds are used alone or in combination of two or more.

A tetraalkylammonium salt type nitrogen-containing basic compound can also be used. Among these, tetraalkylammonium hydroxide having 1 to 8 carbon atoms (tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra- (
n-butyl) ammonium hydroxide and the like are preferred. These nitrogen-containing basic compounds are used alone or in combination of two or more.

The use ratio of the acid generator and the organic basic compound in the composition is preferably (total amount of acid generator) / (organic 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) / (organic basic compound) (molar ratio) is preferably 5.0 to 200, more preferably 7.0 to 150.

[4] Surfactant In the present invention, a surfactant can be used, which is 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 Sorbitan mono palmitate - door,

Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, F-top EF301, EF303, EF352 (Shin-Akita Kasei) (Made by Co., Ltd.), MegaFuck F171, F173 (Dainippon Ink Chemical Co., Ltd.), Florad FC430, FC431 (Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC101, SC102 , SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), Troysol S-366 (manufactured by Troy Chemical Co., Ltd.), silicon surfactants, organosiloxane polymer KP341 Shin-Etsu Chemical Co., Ltd.) 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.

The surfactant is any one of fluorine and / or silicon surfactants (fluorine surfactants and silicon surfactants, surfactants containing both fluorine atoms and silicon atoms), or It is preferable to contain 2 or more types.
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).

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

In the present invention, a dye can be used.
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.

  Examples of the photobase generator that can be added to the composition of the present invention include JP-A-4-151156, JP-A-4-162040, JP-A-5-197148, JP-A-5-5995, JP-A-6-194634, and JP-A-8-146608. No. 10-83079 and European Patent No. 622682, specifically, 2-nitrobenzyl carbamate, 2,5-dinitrobenzyl cyclohexyl carbamate, N-cyclohexyl-4-methylphenylsulfonamide 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate and the like can be preferably used. These photobase generators are added for the purpose of improving the resist shape and the like.

[6] Solvent 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.

[7] Pattern Formation Method The positive resist composition of the present invention is applied on 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 absorbing agent, 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, AR-2, AR-3, AR-5 manufactured by Shipley, etc. 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 in detail, this invention is not limited to these. In addition, Examples 1, 2, 6-9, 13-16, 18 and 19 are reference examples.

Synthesis Example 1: Synthesis of resin specific example (P-1) Acetoxystyrene and 1,4-bis (2′-hydroxypropyl) benzene dimethacrylate were charged at a ratio (molar ratio) of 96/4 and dissolved in tetrahydrofuran. 100 mL of a solution having a solid content concentration of 20% by mass was prepared. 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 95/5 (molar ratio). Moreover, the weight average molecular weight of standard polystyrene conversion calculated | required by GPC measurement was 8500.
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 9000.
20 g of the polymer obtained above was dissolved in 100 ml of THF, 7 g of ethyl vinyl ether was added, 100 mg of p-toluenesulfonic acid was added, and the mixture was stirred at room temperature for 3 hours. After neutralizing by adding 300 mg of triethylamine, it was poured into 2 L of distilled water with stirring and reprecipitated. The obtained solid was filtered and then dried under reduced pressure at room temperature. The composition ratio of the obtained resin was 65/30/5 (molar ratio), and the weight average molecular weight was 10,000.
Similarly, the polymers P-3, P-5, P-7, P-9 exemplified above and the following comparative resin R-1 were synthesized. Table 1 shows the molar composition ratio of the repeating units (repetition on the left). (In order from unit) and weight average molecular weight.

[Example 1]
(1) Resin (P-1) 0.93g
Sulfonic acid generator B-2 0.065g
Is dissolved in 8.8 g of propylene glycol monomethyl ether acetate, 0.001 g of D-1 (see below) as an organic 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) Production of Positive Resist Pattern This resist film was irradiated with an electron beam using an electron beam drawing apparatus (HL750, acceleration voltage 50 KeV manufactured by Hitachi, Ltd.). 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 width 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 9.5 μC / cm ² , the LWR was 6.8 nm, and the density dependency was 10 nm.

[Examples 2 to 7 and Comparative Example 1]
Using the compounds shown in Table 2, 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 2.

The component (c) used in the examples, other components, and the resins used in the comparative examples are shown below.
[Organic basic compound (base)]
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 (Dainippon Ink Chemical Co., Ltd.)
W-2: Fluorine / silicone surfactant, MegaFac R08 (manufactured by Dainippon Ink & Chemicals, Inc.)
W-3: Silicon-based surfactant, siloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.)

  From Table 2, it can be seen that the positive resist composition of the present invention is higher in sensitivity, and has better roughness and density dependency than the composition of Comparative Example 1 in terms of pattern formation by electron beam irradiation. .

[Examples 8 to 14 and Comparative Example 2]
The resist was prepared and coated as shown in Table 3 by the same operation as in Example 1 to obtain a resist film. However, the film thickness was 0.40 μm.

(3) Formation 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) Roughness With respect to the resist pattern obtained in the same manner as described above, the line width was observed with a scanning electron microscope (S-9220, manufactured by Hitachi, Ltd.), and the fluctuation of the line width at the line width of 110 nm (LWR). ) 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.
(3-4) Etching Rate Ratio For the resist film, an etching apparatus manufactured by ULVAC is used, the etching gas is CHF ₃ / O ₂ = 16/4, the pressure is 20 mTorr, and the applied power is 100 mW / cm ^3. After processing the film, the etching rate of the resist film was determined from the change in the film thickness of the resist. The ratio with the etching rate when the resin of the comparative example was used under the same conditions was calculated.

  From Table 3, the positive resist composition of the present invention is higher in sensitivity than the composition of Comparative Example 2 with respect to pattern formation by KrF excimer laser exposure, and has excellent roughness, density dependence, and etching resistance. I understand that.

[Examples 15 to 19 and Comparative Example 3]
Using each resist composition shown in Table 4, a resist film was obtained in the same manner as in Example 1. 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 4.

  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 Comparative Example 3 in the characteristic evaluation by irradiation with EUV light.

Claims (6)

(A) A positive resist composition comprising a resin that is soluble in an organic solvent and has increased solubility in an alkali developer by the action of an acid, and (B) a compound that generates an acid upon irradiation with actinic rays or radiation. And
The resin (A) has a structure crosslinked by a crosslinking group, and the crosslinking group has an aromatic ring and an acid-decomposable group that decomposes by the action of an acid to generate an alkali-soluble group .
The resin (A) contains a repeating unit represented by the following general formula (A1) or (A2) and a repeating unit represented by the following general formula (A3), and the crosslinking group is represented by the following general formula (A1) Or a positive resist composition characterized by being linked to a repeating unit represented by (A2) and not linked to a repeating unit represented by the following general formula (A3) .

In the general formulas (A1) and (A2), X represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or an alkyloxycarbonyl group.
A ₁ represents a hydrogen atom or a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.
S ₁ represents a monovalent substituent.
m and n each represents an integer of 0 to 3. However, m + n ≦ 5.
A ₂ represents a group containing a group decomposing by the action of an acid or a group decomposing by the action of an acid.

R ₁ represents a hydrogen atom, a methyl group, a cyano group or a halogen atom.
R ₂ represents an alkyl group, a halogen atom, an aryl group, an alkoxy group or an acyl group.
R ₃ and R ₄ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
Za represents a C6-C30 hydrocarbon group having at least one cyclic structural unit selected from alicyclic, aromatic, and bridged alicyclic.
n represents an integer of 0 to 4. The positive resist composition according to claim 1, wherein Za represents a hydrocarbon group having 6 to 30 carbon atoms having an aromatic cyclic structural unit.   The positive resist composition according to claim 1 or 2, wherein the number of aromatic rings contained in the crosslinking group of the resin (A) is 2 to 8. In the resin (A), the in any one of claims 1 to 3 decomposes group is characterized by a -O-C-O- bond (acetal bonds) by the action of acid contained in the crosslinking group The positive resist composition as described. In the resin (A), the positive resist composition according to claim 1, wherein the group capable of decomposing is an ester bond by the action of acid contained in the crosslinking group. A pattern forming method comprising: forming a resist film with the positive resist composition according to any one of claims 1 to 5; and exposing and developing the resist film.