JP2007086284A - Positive resist composition and pattern forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition having good dissolution contrast and excellent sensitivity under exposure with a high-energy line such as EUV light, and a pattern forming method using the same. <P>SOLUTION: The positive resist composition contains (A) a resin which is decomposed by the action of an acid to increase solubility in an alkali developer and (B) an acid generator having a sulfonium cation represented by formula (B1), wherein R<SB>b1</SB>-R<SB>b3</SB>each independently represent alkyl or aryl, provided that the total number of oxygen atoms contained in R<SB>b1</SB>-R<SB>b3</SB>is ≥4, and two of R<SB>b1</SB>-R<SB>b3</SB>may bond to each other to form a ring. <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 photofabrication processes. More specifically, the present invention relates to a positive type photoresist that can form a high-definition pattern using EUV light or the like, and relates to a positive type resist composition that can be suitably used for fine processing of a semiconductor element using EUV light or the like.

  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. 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.

  As a resist suitable for a lithography process using such electron beam, X-ray or EUV light, a chemically amplified resist using an acid catalyst reaction is mainly used from the viewpoint of high sensitivity. As a main component, a phenolic polymer (hereinafter abbreviated as a phenolic acid-decomposable resin) that is insoluble or hardly soluble in an alkali developer and becomes soluble in an alkali developer by the action of an acid, and an acid generator A chemically amplified resist composition comprising:

  With regard to positive resists for EUV exposure, a resist that uses a phenolic acid-decomposable resin and contains a relatively large amount of a compound that generates sulfonic acid upon irradiation with actinic rays or radiation (hereinafter abbreviated as sulfonic acid generator) Several compositions are known (see, for example, Patent Documents 1 and 2).

  However, when EUV is used as a light source, since the wavelength of light belongs to the extreme ultraviolet region and has high energy, there has been a problem regarding a reduction in contrast due to concerted photochemical reactions such as negativity caused by EUV light. Furthermore, since EUV light has high linearity and exposure is performed using a mirror, it is known that the mirror is deteriorated by high energy rays such as EUV light. From the viewpoint of shortening the exposure time, the resist is also known. There is a need for higher sensitivity.

JP 2002-55457 A JP 2003-345023 A

  An object of the present invention is to provide a positive resist composition having good dissolution contrast and excellent sensitivity under exposure with a high energy beam such as EUV light, and a pattern forming method using the same.

式（Ｂ１）中、
Ｒ_b1〜Ｒ_b3は、各々独立に、アルキル基又はアリール基を表す。但し、Ｒ_b1〜Ｒ_b3に含まれる酸素原子の総数は４つ以上である。
（２）
一般式（Ｂ１）において、Ｒ_b1〜Ｒ_b3のいずれかが酸素原子を３つ以上含有する基であることを特徴とする、上記（１）に記載のポジ型レジスト組成物。
（３）
一般式（Ｂ１）において、Ｒ_b1〜Ｒ_b3の全てがアリール基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）
ＥＵＶ光用であることを特徴とする上記（１）〜（３）のいずれかに記載のポジ型レジスト組成物。
（５）
上記（１）〜（４）のいずれかに記載のレジスト組成物により、感光性膜を形成し、該感光性膜を露光、現像する工程を含むことを特徴とするパターン形成方法。 As a result of intensive studies, the present inventors have achieved the above-described problem with the following configuration.
(1)
(A) a resin that decomposes by the action of an acid and increases the solubility in an alkaline developer, and (B) an acid generator having a sulfonium cation represented by the general formula (B1),
A positive resist composition comprising:

In formula (B1),
R _{b1 to} R _b3 each independently represents an alkyl group or an aryl group. However, the total number of oxygen atoms contained in R _{b1 to} R _b3 is four or more.
(2)
In the general formula (B1), any one of R _{b1 to} R _b3 is a group containing three or more oxygen atoms, the positive resist composition as described in (1) above.
(3)
The positive resist composition as described in (1) or (2) above, wherein in the general formula (B1), all of R _{b1 to} R _b3 are aryl groups.
(4)
The positive resist composition as described in any one of (1) to (3) above, which is for EUV light.
(5)
A pattern forming method comprising a step of forming a photosensitive film from the resist composition according to any one of (1) to (4), and exposing and developing the photosensitive film.

Furthermore, the following structure can be mentioned as a preferable aspect.
(6) The positive resist composition as described in any one of (1) to (5) above, which further contains a surfactant (C).
(7) The compound (B) that generates an acid by the action of EUV light contains a compound that generates an organic sulfonic acid by the action of EUV light. The positive resist composition as described.
(8) The positive resist composition as described in (7) above, wherein the compound (B) that generates acid by the action of EUV light further contains a compound that generates carboxylic acid by the action of EUV light. .
(9) The positive resist composition as described in any one of (1) to (8) above, which further contains a solvent (D).
(10) The positive resist composition as described in (8) above, which contains propylene glycol monomethyl ether acetate as the solvent (D).
(11) The positive resist composition as described in (10) above, further containing propylene glycol monomethyl ether as the solvent (D).
(12) A process comprising: forming a resist film from the positive resist composition according to any one of (1) to (11) above; and exposing and developing the resist film with EUV light. Pattern forming method.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a positive resist composition having good dissolution contrast and excellent sensitivity under exposure with high energy rays such as EUV light, and a pattern forming method using the same.

Hereinafter, the present invention will be described in detail.
In addition, in the description of a group (atomic group) in this specification, the description which does not describe substituted and unsubstituted 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).

  The positive resist composition of the present invention is an acid generator (B) having a sulfonium cation represented by the resin (A) and the general formula (B1) which decomposes by the action of an acid and increases the solubility in an alkaline developer. And a dissolution inhibiting compound (E) having a molecular weight of 3000 or less, which is further decomposed by the action of an acid to increase the solubility in an alkaline developer as required.

[1] Resin that decomposes by the action of acid and increases its solubility in an alkaline developer (A)
The positive resist composition of the present invention contains a resin (hereinafter also referred to as “acid-decomposable resin”) that is decomposed by the action of an acid to increase the solubility in an alkaline developer.

  The acid-decomposable resin preferably has a repeating unit represented by the following general formula (I) or general formula (II).

In general formula (I),
R ₁ represents a hydrogen atom, a methyl group, a cyano group, a halogen atom or a perfluoro group (preferably having 1 to 4 carbon atoms).
R ₂ represents a hydrogen atom or a non-acid-decomposable group.
X represents a hydrogen atom or an organic group.
m is an integer of 1 to 4, n is an integer of 1 to 4, and 2 ≦ n + m ≦ 5. When m is 2 to 4, the plurality of X may be the same or different, and when n is 2 to 4, the plurality of R ₂ may be the same or different.

In general formula (II):
R ₃ and R ₄ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group.
R ₅ represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, an alkyl group or —C (R ₆ ) (R ₇ ) —O—Y—R ₈ . In the formula, R ₆ and R ₇ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. Y represents a single bond or a carbonyl group. R ₈ represents a hydrogen atom or a hydrocarbon group.
X ₁ represents a hydrogen atom or an organic group.

In the general formula (I), the perfluoro group as R ₁ is preferably a perfluoromethyl group or a perfluoroethyl group. 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.

R ₂ represents a non-acid-decomposable group. A non-acid-decomposable group is a group that is not an acid-decomposable group (a group that decomposes by the action of an acid to produce an alkali-soluble group), that is, an acid generated from a photoacid generator or the like upon exposure to a hydroxyl group, A group that does not generate an alkali-soluble group such as a carboxy group.
Specific examples of the non-acid-decomposable group as R ₂ include, for example, a halogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an acyl group, —OC (═O) Ra, —OC (= O) ORa, -C (= O) ORa, -C (= O) N (Rb) Ra, -N (Rb) C (= O) Ra, -N (Rb) C (= O) ORa, -N (Rb) SO ₂ Ra, may be mentioned _{-SRa, -SO 2 Ra, -SO 3} Ra, or -SO ₂ N (Rb) Ra. In the formula, Ra and Rb represent an alkyl group, a cycloalkyl group, or an aryl group.

The alkyl group as R ₂ may have a substituent, for example, an alkyl group having 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an n-butyl group. , Sec-butyl group, hexyl group and octyl group can be preferably mentioned.
The cycloalkyl group as R ₂ may have a substituent, for example, a cycloalkyl group having 3 to 15 carbon atoms, specifically, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group. Can be preferably mentioned.
The alkoxy group as R ₂ may have a substituent, for example, the above alkoxy group having 1 to 8 carbon atoms, for example, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy Group, cyclohexyloxy group and the like.

The aryl group as R ₂ may have a substituent, for example, an aryl group having 6 to 15 carbon atoms, and specifically includes a phenyl group, a tolyl group, a naphthyl group, an anthryl group, and the like. Preferable examples can be given.

The acyl group as R ₂ may have a substituent, for example, an acyl group having 2 to 8 carbon atoms, specifically, formyl group, acetyl group, propanoyl group, butanoyl group, pivaloyl Preferred examples include groups and benzoyl groups.

  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.). As for the cyclic structure, examples of the substituent further include an alkyl group (preferably having 1 to 8 carbon atoms).

The alkyl group, cycloalkyl group or aryl group as Ra and Rb is the same as those exemplified as R ₂ .

  The organic group as X preferably has 1 to 40 carbon atoms and may be an acid-decomposable group or a non-acid-decomposable group.

Examples of the non-acid-decomposable group include the same organic groups as those in the non-acid-decomposable group as R ₂ . Since it is an organic group, it does not contain halogen atoms.
Further, for example, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkyloxy group (excluding -O-tertiary alkyl), an acyl group, a cycloalkyloxy group, an alkenyloxy group, an aryloxy group, Examples thereof include an alkylcarbonyloxy group, an alkylamidomethyloxy group, an alkylamide group, an arylamidomethyl group, an arylamido group.
The non-acid-decomposable group is preferably an acyl group, an alkylcarbonyloxy group, an alkyloxy group, a cycloalkyloxy group, an aryloxy group, an alkylamidooxy group, or an alkylamido group, more preferably an acyl group or an alkylcarbonyl group. An oxy group, an alkyloxy group, a cycloalkyloxy group, and an aryloxy group;
In the non-acid-decomposable group, the alkyl group is preferably an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, or a t-butyl group. As the alkyl group, those having 3 to 10 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclohexyl group and adamantyl group are preferable, and as the alkenyl group, carbon number such as vinyl group, propenyl group, allyl group and butenyl group. Those having 2 to 4 carbon atoms are preferred, those having 2 to 4 carbon atoms such as vinyl, propenyl, allyl and butenyl groups are preferred as alkenyl groups, and phenyl, xylyl and toluyl groups are preferred as aryl groups. And those having 6 to 14 carbon atoms such as cumenyl group, naphthyl group and anthracenyl group are preferable. The alkoxy group is preferably an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a hydroxyethoxy group, a propoxy group, a hydroxypropoxy group, an n-butoxy group, an isobutoxy group, or a sec-butoxy group.

As the organic group of the acid-decomposable group of X, for example, —C (R _11a ) (R _12a ) (R _13a ), —C (R _14a ) (R _15a ) (OR _16a ), —CO—OC (R _11a ) ( _R12a ) ( _R13a ).
R _{11a to} R _13a each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R _14a and R _15a each independently represents a hydrogen atom or an alkyl group. R _16a represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. Two of R _11a , R _12a and R _13a , or two of R _14a , R _15a and R _16a may be bonded to form a ring.
The alkyl groups of R _{11a to} R _13a and R _16a are substituted with a cycloalkyl group, a hydroxy group, an alkoxy group, an oxo group, an alkylcarbonyl group, an alkyloxycarbonyl group, an alkylcarbonyloxy group, an alkylaminocarbonyl group, an alkyl group. It may have a carbonylamino group, an alkylsulfonyl group, an alkylsulfonyloxy group, an alkylsulfonylamino group, an alkylaminosulfonyl group, an aminosulfonyl group, a halogen atom, a cyano group, or the like.
The aryl groups of R _{11a to} R _13a and R _16a are substituted with an alkyl group, a cycloalkyl group, a hydroxy group, an alkoxy group, an oxo group, an alkylcarbonyl group, an alkyloxycarbonyl group, an alkylcarbonyloxy group, an alkylaminocarbonyl group. Group, alkylcarbonylamino group, alkylsulfonyl group, alkylsulfonyloxy group, alkylsulfonylamino group, alkylaminosulfonyl group, aminosulfonyl group, halogen atom, cyano group and the like.
The alkyl group, cycloalkyl group, alkenyl group, and aralkyl group of R _{11a to} R _16a are each in the middle of ether group, thioether group, carbonyl group, ester group, amide group, urethane group, ureido group, sulfonyl group, sulfone group. Etc. may be included.
A group having an acid-decomposable group can also be introduced into X in the general formula (I) by modification. Thus, X which introduce | transduced the acid-decomposable group is as follows, for example.
-[C ( _R17a ) ( _R18a )] _p- CO-OC ( _R11a ) ( _R12a ) ( _R13a )
R _17a and R _18a each independently represents a hydrogen atom or an alkyl group. p is an integer of 1 to 4.

In general formula (I), X preferably has an alicyclic structure and / or an aromatic ring structure.
In general formula (I), X is preferably an acid-decomposable group.

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

In the general formula (II), the alkyl group as R _{3 to} R ₅ is preferably an alkyl group having 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. .

The hydrocarbon group as R ₈ in the general formula (II) is, for example, an alkyl group (preferably 1 to 20 carbon atoms), a cycloalkyl group (preferably 3 to 20 carbon atoms), an aryl group (preferably 6 carbon atoms). -14), an aralkyl group (preferably having 8 to 20 carbon atoms), and may have a hetero atom such as an oxygen atom in the chain of the alkyl group. Examples of the substituent that the alkyl group and cycloalkyl group may have as R ₈ include a carboxylic acid group and an oxo group.
As the hydrocarbon group for R ₈ , for example, methyl group, linear or branched propyl group, linear or branched butyl group, linear or branched pentyl group, linear or branched hexyl group, cyclohexyl group, adamantyl, norbornyl, butyrolactone, Examples include cyclohexane lactone, norbornane lactone, phenyl group, naphthyl group, anthracenyl group, benzyl group, phenethyl group, and cumyl group.

As the alkyl group of R ₆ and R ₇ in the general formula (II), a linear or branched alkyl group having 1 to 12 carbon atoms is preferable, and a linear or branched alkyl group having 1 to 10 carbon atoms is more preferable. And more preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a pentyl group, a hexyl group, and a heptyl group. Can do.

The cycloalkyl group of R ₆ and R ₇ preferably has 3 to 30 carbon atoms, more preferably 5 to 10 carbon atoms, and may be monocyclic or polycyclic, and may have a substituent. . Examples thereof include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group, an adamantyl group, a norbornyl group, a bicyclodecanyl group, and a tricyclodecanyl group.

The aryl group as R ₆ and R ₇ preferably has 6 to 14 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthracenyl group. In addition, the aralkyl group as R3 and R4 preferably includes 8 to 20 carbon atoms, benzyl group, phenethyl group, cumyl group and the like.

Examples of the substituent that each group as R ₆ and R ₇ may have include a hydroxyl group, a halogen atom, a carboxy group, an alkoxy group (preferably having 1 to 4 carbon atoms), an acyl group (formyl group, acetyl group), A nitro group, a cyano group, an acyloxy group (acetoxy group), etc. can be mentioned.
Regarding the ring structure such as an aryl group, examples of the substituent further include an alkyl group (preferably having 1 to 4 carbon atoms).

The organic group as X ₁ preferably has 1 to 40 carbon atoms and may be an acid-decomposable group or a non-acid-decomposable group.

Examples of the non-acid-decomposable group include the same organic groups as those in the non-acid-decomposable group as R ₂ . Since it is an organic group, it does not contain halogen atoms.
Further, for example, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkyloxy group (excluding -O-tertiary alkyl), an acyl group, a cycloalkyloxy group, an alkenyloxy group, an aryloxy group, Examples thereof include an alkylcarbonyloxy group, an alkylamidomethyloxy group, an alkylamide group, an arylamidomethyl group, an arylamido group.
The non-acid-decomposable group is preferably an acyl group, an alkylcarbonyloxy group, an alkyloxy group, a cycloalkyloxy group, an aryloxy group, an alkylamidooxy group, or an alkylamido group, more preferably an acyl group or an alkylcarbonyl group. An oxy group, an alkyloxy group, a cycloalkyloxy group, and an aryloxy group;
In the non-acid-decomposable group, the alkyl group is preferably an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, or a t-butyl group. As the alkyl group, those having 3 to 10 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclohexyl group and adamantyl group are preferable, and as the alkenyl group, carbon number such as vinyl group, propenyl group, allyl group and butenyl group. Those having 2 to 4 carbon atoms are preferred, those having 2 to 4 carbon atoms such as vinyl, propenyl, allyl and butenyl groups are preferred as alkenyl groups, and phenyl, xylyl and toluyl groups are preferred as aryl groups. And those having 6 to 14 carbon atoms such as cumenyl group, naphthyl group and anthracenyl group are preferable. The alkoxy group is preferably an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a hydroxyethoxy group, a propoxy group, a hydroxypropoxy group, an n-butoxy group, an isobutoxy group, or a sec-butoxy group.

As the organic group of the acid-decomposable group for X ₁ , for example, —C (R _11a ) (R _12a ) (R _13a ), —C (R _14a ) (R _15a ) (OR _16a ), —CO—OC ( R _11a ) (R _12a ) (R _13a ) can be mentioned.
R _{11a to} R _13a each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R _14a and R _15a each independently represents a hydrogen atom or an alkyl group. R _16a represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. Two of R _11a , R _12a and R _13a , or two of R _14a , R _15a and R _16a may be bonded to form a ring.
The alkyl groups of R _{11a to} R _13a and R _16a are substituted with a cycloalkyl group, a hydroxy group, an alkoxy group, an oxo group, an alkylcarbonyl group, an alkyloxycarbonyl group, an alkylcarbonyloxy group, an alkylaminocarbonyl group, an alkyl group. It may have a carbonylamino group, an alkylsulfonyl group, an alkylsulfonyloxy group, an alkylsulfonylamino group, an alkylaminosulfonyl group, an aminosulfonyl group, a halogen atom, a cyano group, or the like.
The aryl groups of R _{11a to} R _13a and R _16a are substituted with an alkyl group, a cycloalkyl group, a hydroxy group, an alkoxy group, an oxo group, an alkylcarbonyl group, an alkyloxycarbonyl group, an alkylcarbonyloxy group, an alkylaminocarbonyl group. Group, alkylcarbonylamino group, alkylsulfonyl group, alkylsulfonyloxy group, alkylsulfonylamino group, alkylaminosulfonyl group, aminosulfonyl group, halogen atom, cyano group and the like.
The alkyl group, cycloalkyl group, alkenyl group, and aralkyl group of R _{11a to} R _16a are each in the middle of ether group, thioether group, carbonyl group, ester group, amide group, urethane group, ureido group, sulfonyl group, sulfone group. Etc. may be included.
Note that a group having an acid-decomposable group can be introduced into X ₁ by modification. Thus, X which introduce | transduced the acid-decomposable group is as follows, for example.
-[C ( _R17a ) ( _R18a )] _p- CO-OC ( _R11a ) ( _R12a ) ( _R13a ) _R17a and _R18a each independently represents a hydrogen atom or an alkyl group. p is an integer of 1 to 4.

The organic group as X ₁ is preferably an acid-decomposable group having at least one cyclic structure selected from alicyclic, aromatic and bridged alicyclic, and an aromatic group (particularly a phenyl group). Or a structure containing an alicyclic or bridged alicyclic structure represented by the following general formulas (pI) to (pV).

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 or alicyclic hydrocarbon group having 1 to 4 carbon atoms, provided that at least one of R _{12 to} R ₁₄ , or Either R 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 or alicyclic hydrocarbon group having 1 to 4 carbon atoms.
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 may be substituted or unsubstituted, and is a linear or branched alkyl group having 1 to 4 carbon atoms. Represents. 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.
Further, the further substituent of the alkyl group includes an alkoxy group having 1 to 4 carbon atoms, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an acyl group, an acyloxy group, a cyano group, a hydroxyl group, A carboxy group, an alkoxycarbonyl group, a nitro group, etc. can be mentioned.

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 that the alicyclic hydrocarbon group may have 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, and more preferably a substituent selected from the group consisting of a methyl group, an ethyl group, a propyl group, and an isopropyl group. To express. 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, alkoxy group, and alkoxycarbonyl group may further have a substituent. Examples of such a substituent include an alkoxy group having 1 to 4 carbon atoms (methoxy group, ethoxy group, butoxy group). Group), hydroxy group, oxo group, alkylcarbonyl group (preferably 2 to 5 carbon atoms), alkylcarbonyloxy group group (preferably 2 to 5 carbon atoms), alkyloxycarbonyl group group (preferably 2 to 2 carbon atoms). 5), halogen atoms (chlorine atom, bromine atom, fluorine atom, etc.) and the like.

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

The acid-decomposable resin has an alkali-soluble group such as a phenolic hydroxyl group, a carboxyl group, a sulfonic acid group, a hexafluoroisopropanol group (—C (CF ₃ ) ₂ ) in order to maintain good developability for an alkali developer. Other suitable polymerizable monomers may be copolymerized so that (OH) can be introduced, and other hydrophobic polymerizable monomers such as alkyl acrylates and alkyl methacrylates may be copolymerized to improve film quality. May be.

  In order to adjust the hydrophilicity / hydrophobicity of the acid-decomposable resin, a methacrylate or acrylate having a hydrophilic group such as alkyleneoxy or lactone may be copolymerized.

  In addition, styrene (alkyl group, halogen atom, alkylthio group, sulfonyl group, ester group may be substituted), vinylnaphthalene (alkyl group, halogen atom, alkylthio group, sulfonyl group, ester group may be substituted) Good), vinyl anthracene (alkyl group, halogen atom, alkylthio group, sulfonyl group, ester group may be substituted), acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, etc. It may be.

  The content of the repeating unit represented by the general formula (I) is preferably 3 to 95 mol%, more preferably 5 to 90 mol%, and particularly preferably 10 to 85 mol% in all repeating units constituting the resin. It is.

  The content of the repeating unit represented by the general formula (II) is preferably 1 to 99 mol%, more preferably 5 to 90 mol%, and particularly preferably 10 to 85 mol% in all repeating units constituting the resin. It is.

The content of the repeating unit having an alkali-soluble group such as a hydroxyl group, a carboxy group, or a sulfonic acid group is preferably 1 to 99 mol%, more preferably 3 to 95 mol%, particularly preferably in all repeating units constituting the resin. 5 to 90 mol%.
The content of the repeating unit having an acid-decomposable group is preferably 3 to 95 mol%, more preferably 5 to 90 mol%, and particularly preferably 10 to 85 mol% in all repeating units constituting the resin.

  Synthesis of the acid-decomposable resin is carried out by a precursor of a group that can be decomposed with an acid into an alkali-soluble resin as described in European Patent No. 254533, JP-A-2-258500, 3-223860, and 4-251259. It can be synthesized by a known synthesis method such as a method of reacting the above, or a method of copolymerizing a monomer having a group decomposable with an acid with various monomers.

The weight average molecular weight (Mw) of the acid-decomposable resin is preferably in the range of 1,000 to 200,000, more preferably in the range of 1,500 to 100,000, and particularly preferably 2,000. It is in the range of 50,000. If it is less than 1,000, it is preferably 1000 or more from the viewpoint of preventing film loss in the unexposed area, and preferably 200,000 or less from the viewpoint of the dissolution rate and sensitivity of the resin itself with respect to alkali. Moreover, it is preferable that molecular weight dispersion degree (Mw / Mn) is 1.0-4.0, More preferably, it is 1.0-3.0, Most preferably, it is 1.0-2.5.
Here, the weight average molecular weight is defined by a polystyrene conversion value of gel permeation chromatography.
Two or more acid-decomposable resins may be used in combination.
The total amount of the acid-decomposable resin is generally 30 to 99% by mass, preferably 40 to 97% by mass, particularly preferably 50 to 95% by mass, based on the solid content of the positive resist composition. is there.

[2] Acid generator (B) having a sulfonium cation represented by general formula (I)
The resist composition of the present invention contains an acid generator (B) having a sulfonium cation represented by the general formula (B1) as a compound (acid generator) that generates an acid upon irradiation with actinic rays or radiation.

In formula (B1),
R _{b1 to} R _b3 each independently represents an alkyl group or an aryl group. However, the total number of oxygen atoms contained in R _{b1 to} R _b3 is four or more.

R _{b1 to} R _b3 are preferably an alkyl group or an aryl group having 1 to 20 carbon atoms and may be unsubstituted or substituted.
The alkyl group is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, more preferably a linear or branched alkyl group having 1 to 12 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. Group, isopropyl group, n-butyl group, isobutyl group, and the like. The cycloalkyl group is preferably a cycloalkyl group having 3 to 20 carbon atoms, more preferably a cycloalkyl group having 5 to 15 carbon atoms, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a norbornyl group, an adamantyl group. Etc. As an aryl group, C6-C14 is preferable, for example, a phenyl group, a naphthyl group, etc. are mentioned.
R _{b1 to} R _b3 are more preferably an aryl group.

Examples of the substituent that the alkyl group and aryl group of R _{b1 to} R _b3 may have include, for example, a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group ( Cycloalkenyl group, bicycloalkenyl group), alkynyl group, aryl group, heterocyclic group (may be referred to as heterocyclic group), cyano group, hydroxyl group, nitro group, carboxyl group, alkoxy group, aryloxy group, Silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group , Aryloxycarbonylamino Group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and arylsulfonyl group, acyl group Aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, hydrazino group, Examples include ureido groups, boronic acid groups (—B (OH) ₂ ), phosphato groups (—OPO (OH) ₂ ), sulfato groups (—OSO ₃ H), and other known substituents.

As a substituent for the alkyl group and aryl group of R _{b1 to} R _b3 , an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group) are preferable. , Alkynyl group, aryl group, heterocyclic group (also referred to as heterocyclic group), cyano group, hydroxyl group, nitro group, carboxyl group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group Carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, Examples include a famoyl group, an alkyl and arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, and a carbamoyl group.

More preferably, the substituent of the alkyl group and aryl group of R _{b1 to} R _b3 is preferably an alkyl group, aryl group, hydroxyl group, carboxyl group, alkoxy group, aryloxy group, acyloxy group, acylamino group, alkyl and arylsulfonylamino group. , A sulfamoyl group, an alkyl and arylsulfonyl group, an alkoxycarbonyl group, and a carbamoyl group, and an alkyl group, an alkoxy group, and an aryloxy group are particularly preferable.

Two of R _{b1 to} R _b3 can be connected to each other to form a ring. Examples of the ring to be formed include an aromatic or non-aromatic hydrocarbon ring or a heterocyclic ring. These can be further combined to form a polycyclic fused ring. Examples of the ring formed include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, Pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring Carbazole ring, phenanthridine ring, acridine ring, phenanthroline ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, and phenazine ring.

The total number of oxygen atoms contained in R _{b1 to} R _b3 is 4 or more, preferably 5 or more, and more preferably 6 or more. It is considered that as the number of oxygen atoms contained in the cation of the acid generator increases, the absorption of exposure light such as EUV increases, and the sensitivity and contrast are improved.
Further, any of R _{b1 to} R _b3 preferably contains three or more oxygen atoms.

  The acid generator having a sulfonium cation represented by the general formula (B1) has a counter anion. As an anion, an organic anion is desirable. An organic anion represents an anion containing at least one carbon atom. Furthermore, the organic anion is preferably a non-nucleophilic anion. A non-nucleophilic anion is an anion that has an extremely low ability to cause a nucleophilic reaction, and is an anion that can suppress degradation over time due to an intramolecular nucleophilic reaction.

Examples of the non-nucleophilic anion include a sulfonate anion, a carboxylate anion, a sulfonylimide anion, a bis (alkylsulfonyl) imide anion, and a tris (alkylsulfonyl) methyl anion.
Examples of the non-nucleophilic sulfonate anion include an alkyl sulfonate anion, an aryl sulfonate anion, and a camphor sulfonate anion. Examples of the non-nucleophilic carboxylate anion include an alkylcarboxylate anion, an arylcarboxylate anion, and an aralkylcarboxylate anion.

  The alkyl moiety in the alkyl sulfonate anion may be an alkyl group or a cycloalkyl group, and preferably an alkyl group having 1 to 30 carbon atoms and a cycloalkyl group having 3 to 30 carbon atoms, such as a methyl group or an ethyl group. Group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group Tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group, boronyl group and the like.

  The aryl group in the aryl 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.

  Examples of the substituent of the alkyl group, cycloalkyl group and aryl group in the alkyl sulfonate anion and aryl sulfonate anion include, for example, a nitro group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), carboxyl group, Hydroxyl group, amino group, cyano group, alkoxy group (preferably 1 to 5 carbon atoms), cycloalkyl group (preferably 3 to 15 carbon atoms), aryl group (preferably 6 to 14 carbon atoms), alkoxycarbonyl group (preferably May include 2 to 7 carbon atoms, an acyl group (preferably 2 to 12 carbon atoms), an alkoxycarbonyloxy group (preferably 2 to 7 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.

  Examples of the alkyl moiety in the alkylcarboxylate anion include the same alkyl group and cycloalkyl group as in the alkylsulfonate anion. Examples of the aryl group in the arylcarboxylate anion include the same aryl groups as in the arylsulfonate anion. The aralkyl group in the aralkyl carboxylate anion is preferably an aralkyl group having 6 to 12 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylmethyl group.

  Examples of the alkyl group, cycloalkyl group, aryl group and aralkyl group substituent in the alkylcarboxylate anion, arylcarboxylate anion and aralkylcarboxylate anion include, for example, the same halogen atom, alkyl group as in the arylsulfonate anion, A cycloalkyl group, an alkoxy group, an alkylthio group, etc. can be mentioned. Examples of the sulfonylimide anion include saccharin anion.

  The alkyl group in the bis (alkylsulfonyl) imide anion and tris (alkylsulfonyl) methyl anion is preferably an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, An isobutyl group, a sec-butyl group, a pentyl group, a neopentyl group, and the like can be given. Examples of the substituent for these alkyl groups include a halogen atom, an alkyl group substituted with a halogen atom, an alkoxy group, and an alkylthio group.

  Examples of other non-nucleophilic anions include fluorinated phosphorus, fluorinated boron, and fluorinated antimony.

  The counter anion of the sulfonium salt (B) having a cation represented by the general formula (B1) is preferably a sulfonate anion, and more preferably an aryl sulfonic acid.

  Specific examples of counter anions include methane sulfonate anion, trifluoromethane sulfonate anion, pentafluoroethane sulfonate anion, heptafluoropropane sulfonate anion, perfluorobutane sulfonate anion, perfluorohexane sulfonate anion, and perfluoro. Octane sulfonate anion, pentafluorobenzene sulfonate anion, 3,5-bistrifluoromethylbenzene sulfonate anion, 2,4,6-triisopropylbenzene sulfonate anion, perfluoroethoxyethane sulfonate anion, 2, 3, 5 , 6-Tetrafluoro-4-dodecyloxybenzenesulfonate anion, methanesulfonate anion, p-toluenesulfonate anion, 3,5-bistrifluorobenzenesulfonate anion, pentafluoro Nzensuruhon anion, such as 2,4,6-trimethylbenzene sulfonate anions.

  The anion which the sulfonium salt (B) has with the cation represented by the general formula (B1) may be monovalent or divalent. When the anion is divalent or higher, the sulfonium salt (B) can have two or more cations represented by the general formula (B1).

  Specific examples of the sulfonium cation represented by the general formula (B1) are shown below, but the present invention is not limited thereto.

  The compound of the general formula (B1) is synthesized by, for example, a method in which a sulfide compound is oxidized with hydrogen peroxide to form a sulfoxide, and an aromatic compound is reacted in the presence of an acid catalyst, or a Grignard reagent is reacted. Can do.

  The content of the compound (B) in the positive resist composition of the present invention is preferably 0.001 to 40% by mass, more preferably 0.01 to 20% by mass, based on the total solid content of the composition. Especially preferably, it is 0.1-10 mass%. Moreover, 1 type may be used for a compound (B), and 2 or more types may be mixed and used for it.

(Acid generator that can be used in combination)
In addition to the compound (B), another acid generator may be used in combination.
In the present invention, the other acid generator is used as a photo-initiator for photo-cationic polymerization, a photo-initiator for photo-radical polymerization, a photo-decoloring agent for dyes, a photo-discoloring agent, or a micro resist. These can be used in combination by appropriately selecting from known compounds that generate an acid by the action of active light or radiation, and mixtures thereof.

  For example, diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, onium salts such as arsonium salts, organic halogen compounds, organic metal / organic halides, acid generators having o-nitrobenzyl type protecting groups And compounds capable of generating sulfonic acid by photolysis represented by imino sulfonate and the like, and disulfone compounds.

  Further, a group in which an acid is generated by the action of light, 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-A 63-26653 JP, 55-164824, JP 62-69263, JP 63-146038, JP 63-163452, JP 62-153853, JP 63-146029, etc. 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.

  Although the preferable specific example of the acid generator which may be used together is shown below, it is not limited to these.

As the acid generator used in combination with the compound (B), triarylsulfonium salts or diaryliodonium salts are preferable among the above.
The mass ratio of the total amount of the compound (B) and the other acid generator used in combination is usually 1/1 to 100/1, preferably 1/1 to 10/1. By using an acid generator in combination, outgassing and development defects after exposure are further reduced.

In combination with the compound (B), a compound that generates carboxylic acid upon irradiation with light (carboxylic acid generator) is preferably used from the viewpoint of improving performance such as sensitivity and resolving power.
Moreover, it is also preferable to use together the compound (sulfonic acid generator) which generate | occur | produces a sulfonic acid by light irradiation, and the compound (carboxylic acid generator) which generate | occur | produces carboxylic acid by light irradiation, In this case, a compound (B) is A sulfonic acid generator is preferred.

  The sulfonic acid generator / carboxylic acid generator (mass ratio) is usually 1/1 to 100/1, preferably 1/1 to 10/1. By using an acid generator in combination, outgassing and development defects after exposure are further reduced.

  As the carboxylic acid generator, a compound (B2) represented by the following general formula (BII) is particularly preferable.

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

In the general formula (BII), R _{21 to} R ₂₃ each independently represents an alkyl group, an alkenyl group, or an aryl group, and these groups optionally have a substituent.
The alkyl group, alkenyl group or aryl group as R _{21 to} R ₂₃ may have a substituent, and examples of the substituent for the alkyl group and alkenyl group include a halogen atom (chlorine atom, bromine atom, fluorine atom). Atoms, etc.), aryl groups (phenyl group, naphthyl group etc.), hydroxy groups, alkoxy groups (methoxy group, ethoxy group, butoxy group etc.) and the like. Examples of the substituent of the aryl group 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 each independently preferably represents an alkyl group having 1 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 1 carbon atom. An alkyl group having 6 to 6 carbon atoms and an aryl group having 6 to 18 carbon atoms, 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, an alkenyl group, or an aryl group.
The alkyl group, alkenyl group, and aryl group as R ₂₄ may have a substituent, and examples of the substituent of the alkyl group and alkenyl group include examples of the substituent when R ₂₁ is an alkyl group. The same as those mentioned above. 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, an alkenyl group having 2 to 30 carbon atoms, or an aryl group having 6 to 24 carbon atoms, and more preferably an alkyl group having 1 to 18 carbon atoms. And an aryl group having 6 to 18 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 15 carbon atoms.

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 (BII) 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 (BII). May be.

  Specific preferred examples of the compound (B2) that generates a carboxylic acid upon exposure to light are shown below, but of course not limited thereto.

[3] Nitrogen-containing basic compound (C)
In the present invention, it is preferable to use a nitrogen-containing basic compound from the viewpoints of improving performance such as resolution and improving storage stability.
A preferable nitrogen-containing basic compound that can be used 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.

Here, R ²⁵⁰ , R ²⁵¹ and R ²⁵² are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, Here, R ²⁵⁰ and R ²⁵¹ may combine with each other to form a ring. These may have a substituent. Examples of the alkyl group and cycloalkyl group having a substituent include an aminoalkyl group having 1 to 20 carbon atoms, an aminocycloalkyl group having 3 to 20 carbon atoms, and 1 to 1 carbon atoms. A 20 hydroxyalkyl group or a C 3-20 hydroxycycloalkyl group is preferred.
These may contain an oxygen atom, a sulfur atom, or a nitrogen atom in the alkyl chain.

In the formula, R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R ²⁵⁶ each independently represent an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 3 to 6 carbon atoms.
Further preferred compounds are nitrogen-containing basic compounds having two or more nitrogen atoms of different chemical environments in one molecule, and particularly preferred are compounds containing both an amino group and a ring structure containing a nitrogen atom, or alkylamino A compound having a group.

  Preferred examples include guanidine, aminopyridine, aminoalkylpyridine, aminopyrrolidine, indazole, imidazole, pyrazole, pyrazine, pyrimidine, purine, imidazoline, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine and the like. These compounds may have a substituent, and preferred substituents include an amino group, an aminoalkyl group, an alkylamino group, an aminoaryl group, an arylamino group, an alkyl group, an alkoxy group, an acyl group, an acyloxy group, An aryl group, an aryloxy group, a nitro group, a hydroxyl group, a cyano group, etc. are mentioned.

  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-amino Ethyl pyridine, 3-aminopyrrolidine, pyridine Razine, 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.

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, 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 nitrogen-containing basic compound in the composition is such that (total amount of acid generator) / (nitrogen-containing basic compound) (molar ratio) is 2.5 or more in terms of sensitivity and resolving power. Preferably, it is preferably 300 or less from the viewpoint of the resist pattern and resolution over time until the heat treatment after exposure. (Acid generator) / (nitrogen-containing basic compound) (molar ratio) is more preferably 5.0 to 200, still more preferably 7.0 to 150.

[4] 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 bitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, Ftop EF301, EF303, EF352 (manufactured by Shin-Akita Kasei Co., Ltd.), Mega-Fac 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 (manufactured by Asahi Glass Co., Ltd.), Troysol S-366 (manufactured by Troy Chemical Co., Ltd.) 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.

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.

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) (Corporation), 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 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 composition is applied, dried or baked to form a resist film, and then the resist film is irradiated with exposure light, preferably heated, developed, rinsed and dried to form a good resist pattern be able to.

Examples of the alkaline developer of the resist composition of the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine and the like. Secondary amines such as amines, diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; tetramethylammonium hydroxide; tetraethylammonium An aqueous solution (usually 0.1 to 20% by mass) of an alkali such as a quaternary ammonium salt such as hydroxide or choline, a cyclic amine such as pyrrole or piperidine, or the like 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 alkali concentration of the alkali developer is usually from 0.1 to 20% by mass.
The pH of the alkali developer is usually from 10.0 to 15.0.

  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 polymer (A-1))
In a reaction vessel, 20 g of monodispersed poly (p-hydroxystyrene) (Nippon Soda VP-8000) was dissolved in 100 g of commercially available distilled and purified PGMEA, and this solution was decompressed to 60 ° C. and 20 mmHg to give about 20 g of solvent. Was distilled off with the water remaining in the system. This solution was cooled to 20 ° C., 9.57 g of 2-phenoxyethyl vinyl ether and 1.0 g of p-toluenesulfonic acid were added, and the mixture was stirred at room temperature for 1 hour. Thereafter, 1.16 g of triethylamine was added for neutralization, and 40 g of ethyl acetate and 40 g of water were added for washing operation three times. Thereafter, the amount of the solvent was adjusted to obtain a 30% by mass polymer solution. This polymer is referred to as “polymer (A-1)”. From 13C-NMR analysis, the acetal protection rate of phenolic OH was 34%.
Polymers (A-2) and (A-4) to (A-10) were obtained in the same manner as in Synthesis Example 1 except that the polymer and vinyl ether used were changed.

Synthesis Example 2 (Synthesis of polymer (A-3))
20 g of monodispersed poly (p-hydroxystyrene) (manufactured by Nippon Soda VP-8000) and 8.95 g of 4-dimethylaminopyridine were stirred and dissolved in 100 g of tetrahydrofuran, and di-t-butyl dicarbonate 14 was cooled to 0 ° C. .53 g was added dropwise. After dropping, the mixture was further stirred at room temperature for 3 hours. Thereafter, the mixture was neutralized with 0.1N HCl aqueous solution and extracted with ethyl acetate-water. The organic layer was filtered and added dropwise to 1.5 L of hexane. The powder was taken out by filtration and dried under reduced pressure at 40 ° C. to obtain 26.9 g of polymer (A-3). The protection ratio of the phenolic OH of the polymer (A-3) by 13C-NMR analysis was 39%.

Synthesis Example 3 (Synthesis of polymer (A-11))
In a reaction vessel, 11.35 g (0.07 mol) of 4-acetoxystyrene (Tosoh) and 4.27 g (0.03 mol) of t-butyl methacrylate were dissolved in 40 ml of tetrahydrofuran, and nitrogen gas was allowed to flow through the system while stirring. did. 1.15 g (0.05 mol) of azo radical initiator V-601 (manufactured by Wako Pure Chemical Industries) was added thereto, and the reaction solution was heated to 65 ° C. Thereafter, 2.30 g (0.01 mol) of V-601 was added every 2 hours, and the mixture was heated and stirred for a total of 10 hours. Thereafter, the reaction solution was allowed to cool to room temperature and dropped into 1 L of hexane to precipitate a polymer. The filtered solid was dissolved in 50 ml of acetone, dropped again into 1 L of hexane, and the filtered solid was dried under reduced pressure to obtain 13.4 g of white powder. The above powder, 50 ml of tetrahydrofuran, 10 ml of methanol, 1 ml of distilled water and 5.5 g of tetramethylammonium hydroxide were added to the reaction vessel, and the mixture was stirred at room temperature for 3 hours. After adding 10 ml of 10N HCl aqueous solution, the reaction solution was dropped into 1 L of distilled water to precipitate a solid. This solid was dissolved in 50 ml of acetone, dropped again into 1 L of distilled water, and the precipitated solid was dried under reduced pressure to obtain 9.14 g of polymer (A-11). The weight average molecular weight by GPC was 8800, and the molecular weight dispersity was 1.57. Moreover, from 1H and 13C-NMR analysis, the composition ratio was 73/37 in order from the left of the figure.
Polymers (A-12) to (A-21) were obtained in the same manner as in Synthesis Example 3 except that the monomer used was changed.

  Hereinafter, the structures of the polymers (A-1) to (A-21) are shown.

  Table 1 below shows the weight average molecular weight, molecular weight dispersity, and composition ratio of the polymers (A-1) to (A-21).

[Synthesis of Acid Generator (B3)]
Diphenyl sulfoxide 5.0 g and 1,2,3,5-trimethoxybenzene 5.1 g were dissolved in TFA 20 ml and stirred under ice cooling. Thereto were added 21.0 g of trifluoroacetic anhydride and 4.1 ml of nonafluorobutanesulfonic acid, and the mixture was stirred for 2 hours. Then, it heated up to room temperature and stirred for 4 hours. After the reaction, diisopropyl ether was added to precipitate crystals, and the crystals were collected by filtration. The crystals were washed with diisopropyl ether to obtain 9.5 g of (B3).
300MHz ¹ H-NMR (CDCl3) δ3.73 (m, 9H), δ5.70 (s, 1H), δ7.30 (m, 10H)
Other acid generators were synthesized in the same manner.

Examples and Comparative Examples: Exposure by EUV [Preparation of Resist Composition]
Resin of the present invention shown in Table 2: 0.948 g (in terms of solid content)
Acid generator: 0.05g
Organic basic compound: 0.003 g
Surfactant: 0.002g
Was dissolved in 16.79 g of the solvent shown in Table 3 below to prepare a solution having a solid content concentration of 5.0% by mass. This solution was filtered through a 0.1 μm tetrafluoroethylene filter to obtain a positive resist solution. In addition, in the resist composition for a comparison, resin and acid generators other than this invention were used as needed.

[Pattern preparation and evaluation (EUV)]
Using a spin coater, the positive resist solution prepared as described above is uniformly applied on a silicon wafer that has been subjected to hexamethyldisilazane treatment, and is heated and dried at 120 ° C. for 90 seconds to obtain a positive film having a thickness of 0.15 μm. A mold resist film was formed. The obtained resist film was subjected to surface exposure using EUV light (wavelength 13 nm) while changing the exposure amount in steps of 0.5 mJ within a range of 0 to 10.0 mJ, and further baked at 110 ° C. for 90 seconds. Then, 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 evaluation results are shown in Table 2.

The symbols in Table 2 are as follows.
The acid generator is the one in the specific example described above.

[Comparative acid generator]

[Basic compounds]
C-1: Tri-n-octylamine C-2: 1,5-diazabicyclo [4.3.0] -5-nonene C-3: 2,4,6-triphenylimidazole

[Surfactant]
D-1: MegaFuck F176 (Dainippon Ink Chemical Co., Ltd.)
D-2: Megafuck R08 (manufactured by Dainippon Ink & Chemicals, Inc.)
D-3: Troisol S-366 (manufactured by Troy Chemical Co., Ltd.)

〔solvent〕
E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: Ethyl lactate

  From the results in Table 2, it can be seen that the positive resist composition of the present invention is superior in dissolution contrast and sensitivity as compared with the composition of the comparative example in the property evaluation by irradiation with EUV light.

Claims (5)

(A) a resin that decomposes by the action of an acid and increases the solubility in an alkaline developer, and (B) an acid generator having a sulfonium cation represented by the general formula (B1),
A positive resist composition comprising:

In formula (B1),
R _{b1 to} R _b3 each independently represents an alkyl group or an aryl group. However, the total number of oxygen atoms contained in R _{b1 to} R _b3 is four or more. Two of R _{b1 to} R _b3 may be connected to each other to form a ring. 2. The positive resist composition according to claim 1, wherein in the general formula (B1), any one of R _{b1 to} R _b3 is a group containing three or more oxygen atoms. 3. The positive resist composition according to claim 1, wherein in the general formula (B1), all of R _{b1 to} R _b3 are aryl groups.   The positive resist composition according to claim 1, wherein the positive resist composition is for EUV light.   A pattern forming method comprising: forming a photosensitive film from the resist composition according to claim 1; and exposing and developing the photosensitive film.