JP2006276759A - Positive resist composition for euv exposure, and pattern forming method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent positive resist composition for reducing PEB temperature dependency without any problem of outgasing during exposure, by possessing sufficiently excellent contrast under exposure due to EUV light, and to provide a pattern forming method using it. <P>SOLUTION: The positive resist composition contains a resin containing a repeated unit of a specific structure and increasing solubility to alkali developing liquid due to action of acid, and a sulfonium salt compound generating acid due to action of EVU light of a specific structure. The pattern forming method using it is provided. <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 photoresist capable of forming a pattern with high definition using EUV light (wavelength: around 13 nm), and a positive resist composition that can be suitably used for microfabrication of a semiconductor device using EUV light. Related to things.

  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 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 EUV positive resists, there are resist compositions containing phenolic acid-decomposable resins and containing a relatively large amount of a compound that generates sulfonic acid upon exposure to EUV light (hereinafter abbreviated as sulfonic acid generator). Some are known (see, for example, Patent Documents 1 and 2).

However, when EUV light is used as a light source, the wavelength of the light belongs to the extreme ultraviolet region and has high energy. Therefore, there has been a problem regarding a decrease in contrast due to the concerted photochemical reaction such as negativeization caused by EUV light. . Furthermore, unlike conventional light sources, when high-energy rays such as EUV light are irradiated, the compounds in the resist film are destroyed by fragmentation, volatilizing as low-molecular components during exposure, and contaminating the environment in the exposure machine. Outgassing problems become significant. Various studies have been made on the reduction of outgas, and a top trap layer is provided to suppress volatilization of low molecular weight compounds (see, for example, Patent Document 3), or a radical trapping agent that suppresses decomposition of a polymer. Various attempts such as addition (see, for example, Patent Document 4) have been tried, and an contrivance for reducing the outgas is also desired for the acid generator.
In addition, when using a wafer having a large diameter, it has been found that temperature variations in heating (PEB) using a hot plate after exposure affect the resulting pattern. Improvement is desired.
JP 2002-55457 A JP 2003-75998 A European Patent No. 1480078 specification US Pat. No. 6,680,157

  An object of the present invention is to provide a positive resist composition that has high sensitivity and good contrast under exposure to EUV light and that does not have a problem of outgas during exposure, and a pattern forming method using the same.

  As a result of intensive studies, the present inventors have achieved the above problem with the following configuration.

一般式（Ｉ）において、
Ｒ₁は、水素原子、メチル基、シアノ基、ハロゲン原子又はペルフルオロ基を表す。
Ｒ₂は非酸分解性基を表す。
ｎは０〜４の整数を表す。
一般式（II）において、
Ｒ₃〜Ｒ₅は、各々独立に、水素原子、フッ素原子、塩素原子、シアノ基又はアルキル基を表す。
Ｘ₁は水素原子又は有機基を表す。
（２）
ＥＵＶ露光により発生する酸が、一般式(ＢＩ)で表されるベンゼンスルホン酸であることを特徴とする上記（１）に記載のＥＵＶ露光用ポジ型レジスト組成物。

一般式（ＢＩ）中、
Ｒ_1a、Ｒ_3a、Ｒ_5aは、各々独立に、水素原子又は電子吸引性基を表す。ただし、Ｒ_1a、Ｒ_3a、Ｒ_5aのうち少なくとも１つは電子吸引性基である。
Ｒ_2a、Ｒ_4aは各々独立に水素原子又は電子供与性基を表す。
（３）
樹脂（Ａ）がさらに下記一般式（III）で表される繰り返し単位を含有することを特徴とする上記（１）または（２）に記載のＥＵＶ露光用ポジ型レジスト組成物。

一般式（III）において、
Ｒ₁は、水素原子、メチル基、シアノ基、ハロゲン原子又はペルフルオロ基を表す。
Ｒ₂は非酸分解性基を表す。
Ｘは有機基を表す。
ｎは１≦ｎ≦５の整数、ｍは０≦ｍ≦５の整数であり、１≦ｎ＋ｍ≦５である。
（４）
ベンゼンスルホン酸を発生する化合物（Ｂ）が、一般式（ＢＩ）で表される酸のスルホニウム塩化合物又は一般式（ＢＩ）で表される酸のヨードニウム塩化合物であることを特徴とする上記（２）または（３）に記載のＥＵＶ露光用ポジ型レジスト組成物。
（５）
一般式（II）中のＸ₁及び一般式（III）中のＸの少なくともいずれかが脂環構造又は芳香環構造を含有することを特徴とする上記（３）または（４）に記載のＥＵＶ露光用ポジ型レジスト組成物。 (1)
(A) a resin containing a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II), which increases the solubility in an alkali developer by the action of an acid, and (B) EUV A positive resist composition for EUV exposure, comprising a compound that generates benzenesulfonic acid having at least one electron-withdrawing group at the ortho-position or para-position upon exposure.

In general formula (I):
R ₁ represents a hydrogen atom, a methyl group, a cyano group, a halogen atom or a perfluoro group.
R ₂ represents a non-acid-decomposable group.
n represents an integer of 0 to 4.
In general formula (II):
R _{3 to} R ₅ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group.
X ₁ represents a hydrogen atom or an organic group.
(2)
The positive resist composition for EUV exposure according to (1) above, wherein the acid generated by EUV exposure is benzenesulfonic acid represented by the general formula (BI).

In general formula (BI),
R _1a , R _3a and R _5a each independently represents a hydrogen atom or an electron-withdrawing group. However, at least one of R _1a , R _3a and R _5a is an electron withdrawing group.
R _2a and R _4a each independently represents a hydrogen atom or an electron donating group.
(3)
The positive resist composition for EUV exposure according to the above (1) or (2), wherein the resin (A) further contains a repeating unit represented by the following general formula (III).

In general formula (III),
R ₁ represents a hydrogen atom, a methyl group, a cyano group, a halogen atom or a perfluoro group.
R ₂ represents a non-acid-decomposable group.
X represents an organic group.
n is an integer of 1 ≦ n ≦ 5, m is an integer of 0 ≦ m ≦ 5, and 1 ≦ n + m ≦ 5.
(4)
The compound (B) that generates benzenesulfonic acid is a sulfonium salt compound of an acid represented by the general formula (BI) or an iodonium salt compound of an acid represented by the general formula (BI) The positive resist composition for EUV exposure according to 2) or (3).
(5)
EUV described in (3) or (4) above, wherein at least one of X ₁ in general formula (II) and X in general formula (III) contains an alicyclic structure or an aromatic ring structure A positive resist composition for exposure.

  Furthermore, the following structure can be mentioned as a preferable aspect.

(6)
The positive resist composition for EUV exposure according to any one of the above (1) to (4), further comprising a surfactant.
(7)
The positive resist composition for EUV exposure according to any one of the above (1) to (6), further comprising a compound that generates a carboxylic acid.
(8)
The positive resist composition for EUV exposure according to any one of the above (1) to (7), further comprising a solvent (E).
(9) A process comprising: forming a resist film from the positive resist composition according to any one of (1) to (8) above; and exposing and developing the resist film with EUV light. Pattern forming method.

  According to the present invention, it is possible to provide a resist composition that has a sufficiently good dissolution contrast under EUV light irradiation, has no problem of outgassing during exposure, and has few development defects, 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).

[1] Resin (A) having a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II) whose solubility in an alkaline developer is increased by the action of an acid
The resin contained in the positive resist composition of the present invention has a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II), and has a solubility in an alkali developer by the action of an acid. Is a resin (acid-decomposable resin) that increases, and contains a group (acid-decomposable group) that decomposes by the action of an acid to generate an alkali-soluble group such as a hydroxyl group or a carboxy group.

  The acid-decomposable resin of the present invention contains a repeating unit represented by the general formula (I).

In the general formula (I), R ₁ is a hydrogen atom, (represents the C _m F _{2m + 1} group, m is an integer of 1 to 4) methyl group, a cyano group, a halogen atom or a perfluoro group represents a. R ₂ represents a non-acid-decomposable group. n represents an integer of 0 to 4.

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 non-acid-decomposable group as R ₂ is decomposed by a group that is not an acid-decomposable group (a group that decomposes by the action of an acid to generate an alkali-soluble group), that is, an acid generated from a photoacid generator by exposure. And a group that does not generate an alkali-soluble group such as a hydroxyl group or 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. Here, Ra and Rb each independently represents an alkyl group, a cycloalkyl group, or an aryl 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 cycloalkyl group as R ₂ is, for example, a cycloalkyl group having 3 to 15 carbon atoms, and specific examples include a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group.
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.

  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 .

  In the formula (I), the OH group may be at any position on the benzene ring, but is preferably the meta position or the para position of the styrene skeleton, and particularly preferably the para position.

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

  The resin (A) further contains a repeating unit represented by the following general formula (II).

R _{3 to} R ₅ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group.
X ₁ represents a hydrogen atom or an organic group.

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 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 non-acid-decomposable groups as R ₂ in the general formula (I).
For example, alkyl group, cycloalkyl group, alkenyl group, aryl group, alkyloxy group (excluding -O-tertiary alkyl), acyl group, cycloalkyloxy group, alkenyloxy group, aryloxy group, alkylcarbonyl Examples thereof include an oxy group, an alkylamidomethyloxy group, an alkylamide group, an arylamidomethyl group, and an arylamide 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 preferable, those having 2 to 4 carbon atoms such as vinyl group, propenyl group, allyl group and butenyl group are preferable as alkenyl groups, and phenyl group, xylyl group and toluyl group are preferable 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.

Examples of the acid-decomposable organic group for X ₁ include —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.
Note that a group having an acid-decomposable group can be introduced into X ₁ by modification. In this way, X ₁ introduced with the acid decomposable group is, for example, as follows.
-[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.

The organic group as X ₁ preferably has at least one cyclic structure selected from an alicyclic ring and an aromatic ring, and has a structure including an alicyclic structure represented by the following general formulas (pI) to (pV). It is preferably an acid-decomposable group. The alicyclic structure may be a bridged alicyclic structure.

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 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.
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 (preferably 2 to 5 carbon atoms), alkyloxycarbonyl group (preferably 2 to 5 carbon atoms) And halogen atoms (chlorine atom, bromine atom, fluorine atom, etc.).

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

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

In general formula (III),
R ₁ and R ₂ have the same meanings as R ₁ and R ₂ in the general formula (I).
X represents an organic group.
n is an integer of 0 ≦ n ≦ 5, m is an integer of 0 ≦ m ≦ 5, and 1 ≦ 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.

  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 acid-decomposable group and non-acid-decomposable group for X include the same groups as the acid-decomposable group and non-acid-decomposable group as X ₁ in formula (II).

  As the repeating unit represented by the general formula (III), a repeating unit represented by the formula (IIIa) is preferable.

R ₁ , R ₂ , X and n in the formula (IIIa) have the same meanings as those in the formula (III).

  Specific examples of the repeating unit represented by the general formula (III) are listed below, but the present invention is not limited thereto.

  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.

  The resin (A) may have an acid-decomposable group in the repeating units represented by the general formulas (II) and (III), but may have an acid-decomposable group in other repeating units. .

In addition, examples of the acid-decomposable group that other repeating units may have include, in addition to the acid-decomposable groups that the repeating units represented by the general formulas (II) and (III) may have, for example, —C (= O) -X ₀ -R ₀ can be exemplified. As R ₀ , tertiary alkyl groups such as t-butyl group and t-amyl group, isobornyl group, 1-ethoxyethyl group, 1-butoxyethyl group, 1-isobutoxyethyl group, 1-cyclohexyloxyethyl group and the like 1-alkoxyethyl group, 1-methoxymethyl group, alkoxymethyl group such as 1-ethoxymethyl group, 3-oxoalkyl group, tetrahydropyranyl group, tetrahydrofuranyl group, trialkylsilyl ester group, 3-oxocyclohexyl ester Group, 2-methyl-2-adamantyl group, mevalonic lactone residue and the like. X ₀ represents an oxygen atom, a sulfur atom, -NH -, - NHSO ₂ - or an -NHSO ₂ NH-.

  The molar ratio of the content of the repeating unit represented by the general formula (I) and the repeating unit represented by the general formula (II) in the resin (A) is preferably 1/50: 50/1, more preferably 1. / 30: 30/1, particularly preferably 1/20: 20/1.

  The total amount of the repeating unit represented by the general formula (I) and the repeating unit represented by the general formula (II) is generally 2 to 100 mol% in all repeating units constituting the resin (A), preferably Is 5 to 97 mol%, particularly preferably 7 to 93 mol%.

  The content of the repeating unit represented by the general formula (III) is preferably 1 to 70 mol%, more preferably 3 to 60 mol%, and particularly preferably 5 to 5 mol in all repeating units constituting the resin (A). 50 mol%.

  The content of the repeating unit having an acid-decomposable group is generally 2 to 97 mol%, preferably 4 to 90 mol%, particularly preferably 6 to 85 mol%, in all repeating units constituting the resin. .

  The synthesis of the resin (A) is a precursor of a group that can be decomposed with an acid into an alkali-soluble resin, as described in European Patent No. 254853, 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 resin (A) is preferably 1,000 or more from the viewpoint of maintaining the film thickness of the unexposed area, and preferably 200,000 or less for increasing the dissolution rate with respect to alkali. More preferably, it is the range of 1,500-100,000, Most preferably, it is the range of 2,000-50,000. Moreover, it is preferable that molecular weight distribution (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.
Moreover, you may use resin (A) in combination of 2 or more types.

  The amount of the resin (A) added is generally 10 to 96% by mass, preferably 15 to 96% by mass, particularly preferably 20 to 95% by mass, based on the total solid content of the positive resist. It is.

一般式（ＢＩ）中、Ｒ_1a、Ｒ_3a、Ｒ_5aは同じでも異なっていても良く、水素原子又は電子吸引性基を表す。ただし、Ｒ_1a、Ｒ_3a、Ｒ_5aのうち少なくとも１つは電子吸引性基である。Ｒ_2aとＲ_4aは各々独立に水素原子又は電子供与性基を表す。 [2] Compound (B) that generates acid upon irradiation with EUV light
The resist composition of the present invention contains a compound (B) that generates benzenesulfonic acid having at least one electron-withdrawing group at the ortho or para position by EUV exposure. The generated benzenesulfonic acid is preferably a benzenesulfonic acid represented by the following general formula (BI).

In general formula (BI), R _1a , R _3a and R _5a may be the same or different and each represents a hydrogen atom or an electron-withdrawing group. However, at least one of R _1a , R _3a and R _5a is an electron withdrawing group. R _2a and R _4a each independently represents a hydrogen atom or an electron donating group.

In general formula (BI), R _1a , R _3a , and R _5a are each a hydrogen atom or an electron-withdrawing group. Specific examples of the electron-withdrawing group include a cyano group, a carboxyl group, an acyloxy group, Carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, sulfamoyl group, alkyl and arylsulfinyl group And alkyl and arylsulfonyl groups, acyl groups, aryloxycarbonyl groups, alkoxycarbonyl groups, and carbamoyl groups.

R _1a , R _3a and R _5a are more preferably a hydrogen atom, a cyano group, a carboxyl group, an acylamino group, an alkyl and arylsulfonylamino group, a sulfamoyl group, an alkyl and arylsulfinyl group, an alkyl and arylsulfonyl group, an acyl group, An aryloxycarbonyl group, an alkoxycarbonyl group, and a carbamoyl group, and more preferably a hydrogen atom, a cyano group, a sulfamoyl group, an acyl group, an alkoxycarbonyl group, and a carbamoyl group. However, at least one of R _1a , R _3a and R _5a is an electron withdrawing group. R _2a and R _4a each independently represents a hydrogen atom or an electron donating group.

R _2a and R _4a each independently represents a hydrogen atom or an electron-donating group. Examples of R _2a and R _4a include a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group, Examples include aminocarbonylamino group, mercapto group, alkylthio group, arylthio group, and ureido group. R _2a and R _4a are more preferably a hydrogen atom, an alkyl group, a hydroxyl group, an alkoxy group, an aminocarbonylamino group, a mercapto group, and an alkylthio group, and particularly preferably a hydrogen atom, an alkyl group, an alkoxy group, and an alkylthio group. is there.

  The pKa of benzenesulfonic acid (BI) is preferably smaller than −0.60, more preferably pKa is smaller than −1.00, particularly preferably smaller than −1.40.

  Specific examples of benzenesulfonic acid having at least one electron-withdrawing group at the ortho-position or para-position generated by EUV exposure are shown below, but the present invention is not limited thereto.

  The compound (B) is preferably a sulfonium salt compound or iodonium salt compound of benzenesulfonic acid having at least one electron-withdrawing group at the ortho-position or para-position generated by EUV exposure, and more preferably the following general formula (A1) ) To (A2).

In general formula (A1),
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
X ⁻ represents a sulfonate anion generated by EUV exposure and having a hydrogen atom at the —SO ₃ H site of benzenesulfonic acid having at least one electron-withdrawing group at the ortho or para position.

The carbon number of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ is generally 1-30, preferably 1-20.
It is also possible to form the two members ring structure of the R ₂₀₁ to R _203, an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. The two of the group formed by bonding of the R ₂₀₁ to R _203, there can be mentioned an alkylene group (e.g., butylene, pentylene).
Specific examples of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ include corresponding groups in the compounds (A1a), (A1b) and (A1c) described later.
In addition, the compound which has two or more structures represented by general formula (A1) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (A1) is at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (A1) It may be a compound.

  More preferred components (A1) include compounds (A1a), (A1b), and (A1c) described below.

Compound (A1a) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (A1), arylsulfonium compound, i.e., a compound having arylsulfonium as a cation.
In the arylsulfonium compound, all of R _{201 to} R ₂₀₃ may be an aryl group, or a part of R _{201 to} R ₂₀₃ may be an aryl group, and the rest may be an alkyl group or a cycloalkyl group.
Examples of the arylsulfonium compound include a triarylsulfonium compound, a diarylalkylsulfonium compound, a diarylcycloalkylsulfonium compound, an aryldialkylsulfonium compound, an aryldicycloalkylsulfonium compound, and an arylalkylcycloalkylsulfonium compound.

The aryl group of the arylsulfonium compound is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. When the arylsulfonium compound has two or more aryl groups, the two or more aryl groups may be the same or different.
The alkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, sec- Examples thereof include a butyl group and a t-butyl group.
The cycloalkyl group that the arylsulfonium compound has as necessary is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.
Aryl group, alkyl group of R ₂₀₁ to R _203, cycloalkyl group, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 14 carbon atoms) , An alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, or a phenylthio group may be substituted. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and linear, branched or cyclic alkoxy groups having 1 to 12 carbon atoms, most preferably They are a C1-C4 alkyl group and a C1-C4 alkoxy group. The substituent may be substituted on any one of three R ₂₀₁ to R _203, or may be substituted on all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (A1b) will be described.
The compound (A1b) is a compound in which R _{201 to} R ₂₀₃ in the general formula (A1) each independently represents an organic group having no aromatic ring. Here, the aromatic ring includes an aromatic ring having a hetero atom.
The aromatic ring-free organic group as R ₂₀₁ to R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
R _{201 to} R ₂₀₃ are each independently preferably an alkyl group, a cycloalkyl group, an allyl group or a vinyl group, more preferably a linear or branched 2-oxoalkyl group, 2-oxocycloalkyl group, An alkoxycarbonylmethyl group, particularly preferably a linear or branched 2-oxoalkyl group.
The alkyl group as R ₂₀₁ to R ₂₀₃ may be linear, may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 20 carbon atoms, an ethyl group, a propyl Group, butyl group, pentyl group). The alkyl group as R ₂₀₁ to R ₂₀₃ is a straight-chain or branched 2-oxoalkyl group, an alkoxycarbonylmethyl group are preferred.
The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl). The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is a 2-oxocycloalkyl group is more preferable.
The linear or branched 2-oxoalkyl group as R _{201 to} R ₂₀₃ may have a double bond in the chain, and preferably has> C═O at the 2-position of the alkyl group. The group can be mentioned.
The 2-oxocycloalkyl group as R _{201 to} R ₂₀₃ may have a double bond in the chain, and preferably includes a group having> C═O at the 2-position of the cycloalkyl group. be able to.
The alkoxy group in the alkoxycarbonylmethyl group as R ₂₀₁ to R _203, preferably may be mentioned alkoxy groups having 1 to 5 carbon atoms (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group).
R _{201 to} R ₂₀₃ may be further substituted with a halogen atom, an alkoxy group (eg, having 1 to 5 carbon atoms), an alkoxycarbonyl group (eg, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group. .

  The compound (A1c) is a compound represented by the following general formula (A1c), and is a compound having an arylacylsulfonium salt structure.

In general formula (A1c):
_R213 represents an aryl group which may have a substituent, and is preferably a phenyl group or a naphthyl group.
Preferred substituents on the R _213, an alkyl group, an alkoxy group, an acyl group, a nitro group, a hydroxyl group, an alkoxycarbonyl group and a carboxy group.
R ₂₁₄ and R ₂₁₅ each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
Y ₂₀₁ and Y ₂₀₂ each independently represents an alkyl group, a cycloalkyl group, an aryl group, or a vinyl group.
X ⁻ represents a sulfonate anion generated by EUV exposure and having a hydrogen atom at the —SO ₃ H site of benzenesulfonic acid having at least one electron-withdrawing group at the ortho or para position.
R ₂₁₃ and R ₂₁₄ may be bonded to form a ring structure, R ₂₁₄ and R ₂₁₅ may be bonded to form a ring structure, and Y ₂₀₁ and Y ₂₀₂ are bonded to each other. To form a ring structure. These ring structures may contain an oxygen atom, a sulfur atom, an ester bond, or an amide bond. Examples of the group R ₂₁₃ and R _214, R ₂₁₄ and R _215, Y ₂₀₁ and Y ₂₀₂ are formed by combined include a butylene group and a pentylene group.

The alkyl group as R ₂₁₄ , R ₂₁₅ , Y ₂₀₁ and Y ₂₀₂ is preferably a linear or branched alkyl group having 1 to 20 carbon atoms. The alkyl group as Y ₂₀₁ and Y ₂₀₂ is a 2-oxoalkyl group having> C═O at the 2-position of the alkyl group, an alkoxycarbonylalkyl group (preferably an alkoxy group having 2 to 20 carbon atoms), or a carboxyalkyl group. More preferred.
The cycloalkyl group as R ₂₁₄ , R ₂₁₅ , Y ₂₀₁ and Y ₂₀₂ is preferably a cycloalkyl group having 3 to 20 carbon atoms.
Y ₂₀₁ and Y ₂₀₂ are preferably an alkyl group having 4 or more carbon atoms, more preferably an alkyl group having 4 to 6, and further preferably 4 to 12.
In addition, at least one of R ₂₁₄ or R ₂₁₅ is preferably an alkyl group, and more preferably both R ₂₁₄ and R ₂₁₅ are alkyl groups.

In general formula (A2),
_R204 and _R205 each independently represents an aryl group, an alkyl group or a cycloalkyl group.
X ⁻ represents a sulfonate anion generated by EUV exposure and having a hydrogen atom at the —SO ₃ H site of benzenesulfonic acid having at least one electron-withdrawing group at the ortho or para position.

The aryl group of R ₂₀₄ and R _205, a phenyl group, a naphthyl group, more preferably a phenyl group.
The alkyl group as _R204 and _R205 may be either linear or branched, and is preferably a linear or branched alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group). Group, butyl group, pentyl group).
The cycloalkyl group as R ₂₀₄ and R ₂₀₅ can preferably be mentioned a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
_R204 and _R205 may have a substituent. Examples of the substituent that R ₂₀₄ and R ₂₀₅ may have include, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 6 carbon atoms). 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.

  The compound that generates the organic acid represented by the general formula (I) upon irradiation with actinic rays or radiation is preferably a compound represented by the general formula (A1), more preferably the general formula (A1a) to It is a compound represented by (A1c).

  Specific examples of the compound (B) that generates benzenesulfonic acid having at least one electron-withdrawing group at the ortho-position or para-position by EUV exposure are shown in the following table. The compound (B) is a compound composed of a photosensitive cation moiety and a dissociated anion moiety of benzenesulfonic acid, and the anion in the table represents that the sulfonic acid shown is dissociated in the molecule.

  The structure of the cation in the table is shown below.

(Synthesis of acid generator)
Compound (B) may be commercially available, or can be synthesized by a general method. For example, according to the method of Synthesis 10; 1986; 852-854, each sulfonyl chloride body is obtained from the corresponding bromobenzene body, reacted with tetramethylammonium hydroxide to form sulfonic acid, and salt exchange with the target cation is performed. The acid generator can be synthesized.

  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.

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 EUV 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 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 EUV light (carboxylic acid generator) is preferably used from the viewpoint of improving performance such as sensitivity and resolving power.
It is also preferable to use a compound that generates sulfonic acid by irradiation with EUV light (sulfonic acid generator) and a compound that generates carboxylic acid by irradiation with EUV light (carboxylic acid generator). In this case, compound (B ) Is preferably a sulfonic acid generator.

  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 EUV light are given 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, surfactants are derived from fluoroaliphatic compounds produced by the telomerization method (also referred to as the telomer method) or the oligomerization method (also referred to as the 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). It may be 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. 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) Copolymer) of (ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate), 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 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 applied, dried or baked to form a resist film, and then the resist film is irradiated with EUV, and preferably formed by heating, developing, rinsing and drying. Can do.

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 of resin)
Synthesis Example 1: Synthesis of polymer (A-34)

32.4 g (0.2 mol) of p-acetoxystyrene and 8.97 g (0.07 mol) of tert-butyl acrylate were dissolved in 120 ml of butyl acetate, and azobisisobutyrate at 80 ° C. under a nitrogen stream and stirring. A polymerization reaction was carried out by adding 0.033 g of ronitrile (AIBN) three times every 2.5 hours and finally continuing stirring for another 5 hours. The reaction solution was added to 1200 ml of hexane to precipitate a white resin. The obtained resin was dried and then dissolved in 200 ml of methanol.
To this was added an aqueous solution of 7.7 g (0.19 mol) of sodium hydroxide / 100 ml of methanol / 50 ml of water, and the mixture was hydrolyzed by heating under reflux for 1 hour. Thereafter, 200 ml of water was added for dilution, and neutralized with hydrochloric acid to precipitate a white resin. The resin was filtered off, washed with water and dried. Furthermore, it melt | dissolved in tetrahydrofuran 200 ml, and it dripped and reprecipitated, stirring vigorously in 5 L of ultrapure water. This reprecipitation operation was repeated three times. The obtained resin was dried in a vacuum dryer at 120 ° C. for 12 hours to obtain a polymer (A-34). The weight average molecular weight by gas permeation chromatography (GPC) was 8800, and the molecular weight dispersity (Mw / Mn) was 1.54. From 1H and 13C-NMR analyses, the composition ratio of p-hydroxystyrene / t-butyl acrylate was 75/25.

  Synthesis Example 2: Synthesis of polymer (A-39)

  In a reaction vessel, 30 g of polymer (A-34) is dissolved in 100 g of propylene glycol monomethyl ether acetate, and this solution is decompressed to 60 mm and 20 mmHg to distill off about 20 g of solvent together with water remaining in the system. did. It cooled to 20 degreeC, 2-phenoxyethyl vinyl ether 4.54g and p-toluenesulfonic acid 1.0g were added, and it 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 30% by mass of a polymer. This polymer is designated as A-39. Polymer A-39 had a weight average molecular weight of 9600 by GPC and a molecular weight dispersity of 1.55. From 1H and 13C-NMR analyses, p-hydroxystyrene / p- [1- (2-phenoxyethoxy) ethoxy] styrene The composition ratio of / t-butyl acrylate was 60/15/25.

  Polymers A-1 to A-33 and A-35 to A-38 were obtained in the same manner as in Synthesis Example 1 or 2, except that the monomer or vinyl ether used was changed. The structures of these polymers are shown below.

  Table 2 shows the weight average molecular weight, molecular weight dispersity, and composition ratio of the synthesized polymer.

(Synthesis of acid generator)
10 g of 4-cyanobenzenesulfonyl chloride is dissolved in a mixed solution of 40 ml of methanol and 20 ml of water, and 17.4 ml of 26% tetramethylammonium hydroxide aqueous solution is added. After stirring at 50 degrees for 3 hours, the temperature is returned to room temperature, and hydrochloric acid is added to make the reaction solution acidic. The reaction solution is distilled off under reduced pressure to obtain 14.5 g of crude crystals of 4-cyanobenzenesulfonic acid. Thereafter, 17.0 g of triphenylsulfonium bromide was added thereto, and the mixture was stirred at room temperature for 3 hours. 300 mL of chloroform was added, the organic layer was washed several times with water, and the organic layer was concentrated and dried in vacuo to obtain 18.1 g of triphenylsulfonium 4-cyanobenzenesulfonate (B9).
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 3: 0.948 g (solid content conversion)
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.

[Evaluation of film thickness fluctuation rate after exposure]
Irradiate a dose of 2.0 times the dose (mJ / cm ² ) with the sensitivity determined by performing surface exposure with EUV light, measure the film thickness after exposure (before post-heating), and use the following formula: From this, the rate of change from the unexposed film thickness was determined.
Film thickness fluctuation rate = (film thickness at unexposed-film thickness after exposure) / film thickness at unexposed

[PEB temperature dependence]
After exposure, the difference in sensitivity was evaluated as PEB temperature dependence as shown in the following equation when heated (PEB) on a hot plate at temperatures of 107 ° C. and 113 ° C. for 90 seconds. The smaller this number, the better.
(PEB temperature dependence) = (sensitivity at 113 ° C)-(sensitivity at 107 ° C)

  The evaluation results are shown in Table 3.

  The symbols in Table 3 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.)
D-4: Polyoxyethylene lauryl ether

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

[Comparative resin]
a-0: The following structure, weight average molecular weight 8700, molecular weight dispersity 1.54

  From the results shown in Table 3, the positive resist composition of the present invention is more sensitive to dissolution contrast, film thickness fluctuation rate after exposure, and PEB temperature dependence than the composition of the comparative example in the property evaluation by EUV light irradiation. It turns out that it is excellent at a point. A small film thickness variation rate means that there is little outgas.

Claims (6)

(A) a resin containing a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II), which increases the solubility in an alkali developer by the action of an acid, and (B) EUV A positive resist composition for EUV exposure, comprising a compound that generates benzenesulfonic acid having at least one electron-withdrawing group at the ortho-position or para-position upon exposure.

In general formula (I):
R ₁ represents a hydrogen atom, a methyl group, a cyano group, a halogen atom or a perfluoro group.
R ₂ represents a non-acid-decomposable group.
n represents an integer of 0 to 4.
In general formula (II):
R _{3 to} R ₅ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group.
X ₁ represents a hydrogen atom or an organic group. 2. The positive resist composition for EUV exposure according to claim 1, wherein the acid generated by EUV exposure is benzenesulfonic acid represented by the general formula (BI).

In general formula (BI),
R _1a , R _3a and R _5a each independently represents a hydrogen atom or an electron-withdrawing group. However, at least one of R _1a , R _3a and R _5a is an electron withdrawing group.
R _2a and R _4a each independently represents a hydrogen atom or an electron donating group. The positive resist composition for EUV exposure according to claim 1 or 2, wherein the resin (A) further contains a repeating unit represented by the following general formula (III).

In general formula (III),
R ₁ represents a hydrogen atom, a methyl group, a cyano group, a halogen atom or a perfluoro group.
R ₂ represents a non-acid-decomposable group.
X represents an organic group.
n is an integer of 1 ≦ n ≦ 5, m is an integer of 0 ≦ m ≦ 5, and 1 ≦ n + m ≦ 5.   The compound (B) that generates benzenesulfonic acid is a sulfonium salt compound of an acid represented by the general formula (BI) or an iodonium salt compound of an acid represented by the general formula (BI). The positive resist composition for EUV exposure according to 2 or 3. 5. The EUV exposure positive electrode according to claim 3, wherein at least one of X ₁ in the general formula (II) and X in the general formula (III) contains an alicyclic structure or an aromatic ring structure. Type resist composition.   A pattern forming method comprising: forming a resist film from the positive resist composition according to claim 1; and exposing and developing the resist film with EUV light.