JP2008195868A - Resin, positive resist composition and pattern forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition improved in LER (line edge roughness), pattern collapse and development faults. <P>SOLUTION: A resin having recurring units represented by general formula (I), produced by living radical polymerization and capable of becoming alkali-solubilized by the action of an acid is provided, and a resist composition containing the resin and a pattern forming method using the composition are also provided. (Wherein, X<SB>a1</SB>is an hydrogen atom, an alkyl group or a cycloalkyl group; and R is an acid-decomposable group containing a monocyclic alicycle). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polymer used in a process for producing a semiconductor such as an IC, production of a circuit board such as a liquid crystal or a thermal head, and other photofabrication processes, and a polymer produced by the production method. The present invention relates to a positive resist composition to be contained, a pattern forming method using the same, and a compound used for producing a polymer thereof. More specifically, a method for producing a polymer, and a polymer produced by the production method, which are suitably used when an exposure light source such as far ultraviolet rays of 250 nm or less, preferably 220 nm or less, and an irradiation source using an electron beam or the like are used. The present invention relates to a positive resist composition containing a compound, a pattern forming method using the same, and a compound used for producing a polymer thereof.

  The chemically amplified photosensitive composition generates an acid in the exposed area by irradiation with radiation such as far ultraviolet light, and the acid-catalyzed reaction causes the solubility of the active radiation irradiated area and non-irradiated area in the developer. This is a pattern forming material for changing the pattern to form a pattern on the substrate.

  When a KrF excimer laser is used as an exposure light source, a resin having a basic skeleton of poly (hydroxystyrene) having a small absorption mainly in the 248 nm region is used as a main component. A pattern is formed, which is a better system than the conventional naphthoquinone diazide / novolak resin system.

On the other hand, when a further short wavelength light source, for example, an ArF excimer laser (193 nm) is used as an exposure light source, the compound having an aromatic group exhibits a large absorption in the 193 nm region. It wasn't.
For this reason, resists for ArF excimer lasers containing a resin having an alicyclic hydrocarbon structure have been developed (see, for example, Patent Document 1 and Patent Document 2). These resins are generally produced by solution polymerization in which a solution containing a polymerization initiator and a monomer is heated to polymerize.

  However, as pattern miniaturization progresses, the influence of dispersion (dispersion degree) in the molecular weight of the resin on resist performance (pattern collapse, line edge roughness, development defect, etc.) can no longer be ignored. Examples using living radical polymerization have been reported as a method for controlling the degree of dispersion of a resist resin (see, for example, Patent Documents 3 to 5). However, the resin having an acid-decomposable protecting group used in Patent Documents 3 to 5 cannot obtain sufficient LER (line edge roughness) and pattern collapse resistance.

JP-A-9-73173 US Pat. No. 6,388,101B Japanese Patent Laid-Open No. 2004-220009 JP 2005-156726 A International Publication No. 2004 / 114,022 Pamphlet

  An object of the present invention is to provide a LER (Line Edge Roughness), a narrowly dispersible resin capable of improving pattern collapse, a method for producing the resin, a positive resist composition containing the resin, and a pattern forming method using the resin. There is to do.

  The present inventor has intensively studied to achieve the above object, and as a result, a resin containing a group that is narrowly dispersed and decomposes and leaves by the action of a specific acid, and a positive resist composition containing the same, are LER. It has been found that resist performance such as (line edge roughness) and pattern collapse is improved. Furthermore, it was possible to find a reduction in development defects, leading to the present invention.

  The present invention has the following configuration.

一般式（Ｉ）中、
Ｘ_ａ１は水素原子、アルキル基、またはシクロアルキル基を表す。
Ｒは単環の脂環基を含有する酸の作用により分解して脱離する基を表す。
＜２＞
樹脂（Ｂ）において一般式（Ｉ）で表される繰り返し単位が一般式（Ｉａ）で表されるで繰り返し単位であることを特徴とする上記＜１＞に記載の樹脂。

一般式（Ｉａ）中、
Ｘ_ａ１は水素原子、アルキル基、またはシクロアルキル基を表す。
Ｒ_１、Ｒ_２及びＲ_３はそれぞれ独立してアルキル基、単環の脂環基を表す。ただし、Ｒ_１、Ｒ_２及びＲ_３の少なくとも一つは単環の脂環基である。
＜３＞
樹脂（Ｂ）がさらに一般式（Ｉ’）で表され、繰り返し単位（ａ）とは異なる構造を有する繰り返し単位（ｂ）を含有することを特徴とする上記＜１＞または＜２＞に記載の樹脂。

一般式（Ｉ’）中、
Ｘ_ａ２は水素原子、アルキル基、またはシクロアルキル基を表す。
Ｒ’は酸の作用により分解して脱離する基を表す。
ただし、Ｘａ₂が一般式（Ｉ）におけるＸａ₁と同じ場合、Ｒ’は一般式（Ｉ）におけるＲと同じではなく、また、Ｒ’が一般式（Ｉ）におけるＲと同じ場合の場合、Ｘａ₂は一般式（Ｉ）におけるＸａ₁と同じではない。
＜４＞
樹脂（Ｂ）がさらにラクトン構造を有する繰り返し単位（ｃ）を含有することを特徴とする上記＜１＞〜＜３＞のいずれかに記載の樹脂。
＜５＞
樹脂（Ｂ）がさらに極性基を有する繰り返し単位を含有することを特徴とする上記＜１＞〜＜４＞のいずれかに記載の樹脂。
＜６＞
樹脂（Ｂ）がさらに非酸分解性脂環構造を含有する繰り返し単位を有することを特徴とする上記＜１＞〜＜５＞のいずれかに記載の樹脂。
＜７＞
樹脂（Ｂ）を製造するリビングラジカル重合が、一般式（ＩＩ）で表される連鎖移動剤の存在下で重合されたことを特徴とする上記＜１＞〜＜６＞のいずれかに記載の樹脂。

一般式（ＩＩ）中、
Ａはアルキル基、シクロアルキル基、アルコキシ基、アルキルチオ基、アリールチオ基、ヘテロ環チオ基、アリール基またはヘテロ環基を表す。
Ｙはアリール基を含有しないラジカルを放出できる基を表す。
＜８＞
前記一般式（ＩＩ）で表される連鎖移動剤が一般式（ＩＩ’）で表されることを特徴とする上記＜７＞に記載の樹脂。

一般式（ＩＩ’）中、
Ａ_１及びＡ_２は各々独立してアルキル基、シクロアルキル基、アルコキシ基、アルキルチオ基、アリールチオ基、ヘテロ環チオ基、アリール基またはヘテロ環基を表す。
＜９＞
前記樹脂（Ｂ）の製造工程が、
一般式（ＩＩＩ）で表される末端構造をラジカル発生剤で置換する際、ラジカル発生剤を逐次添加する工程を含むことを特徴とする上記＜１＞〜＜８＞のいずれかに記載の樹脂。

一般式（ＩＩＩ）中、
Ａはアルキル基、シクロアルキル基、アルコキシ基、アルキルチオ基、アリールチオ基、ヘテロ環チオ基、アリール基またはヘテロ環基を表す。
＜１０＞
（Ａ）活性光線又は放射線の照射により酸を発生する化合物、および（Ｂ）上記＜１＞〜＜９＞のいずれかに記載の樹脂、を含有するポジ型レジスト組成物
＜１１＞
さらに塩基性化合物を含有することを特徴とする上記＜１０＞に記載のポジ型レジスト組成物。
＜１２＞
上記＜１０＞または＜１１＞に記載のポジ型レジスト組成物により、膜を形成し、該膜を露光、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。 <1>
A resin (B) which contains the repeating unit (a) represented by the general formula (I) and which is produced by living radical polymerization and becomes alkali-soluble by the action of an acid.

In general formula (I),
X _a1 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R represents a group capable of decomposing and leaving by the action of an acid containing a monocyclic alicyclic group.
<2>
The resin according to <1>, wherein the repeating unit represented by the general formula (I) in the resin (B) is a repeating unit represented by the general formula (Ia).

In general formula (Ia),
X _a1 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R ₁ , R ₂ and R ₃ each independently represents an alkyl group or a monocyclic alicyclic group. However, at least one of R ₁ , R ₂ and R ₃ is a monocyclic alicyclic group.
<3>
<1> or <2>, wherein the resin (B) further contains a repeating unit (b) represented by the general formula (I ′) and having a structure different from that of the repeating unit (a) Resin.

In general formula (I ′),
X _a2 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R ′ represents a group capable of decomposing by the action of an acid.
However, when Xa ₂ is the same as Xa ₁ in general formula (I), R ′ is not the same as R in general formula (I), and when R ′ is the same as R in general formula (I), Xa ₂ is not the same as Xa ₁ in general formula (I).
<4>
The resin according to any one of <1> to <3> above, wherein the resin (B) further contains a repeating unit (c) having a lactone structure.
<5>
Resin (B) contains the repeating unit which has a polar group further, Resin in any one of said <1>-<4> characterized by the above-mentioned.
<6>
Resin (B) has a repeating unit containing a non-acid-decomposable alicyclic structure further, Resin in any one of said <1>-<5> characterized by the above-mentioned.
<7>
The living radical polymerization for producing the resin (B) is polymerized in the presence of a chain transfer agent represented by the general formula (II), according to any one of the above <1> to <6> resin.

In general formula (II),
A represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group.
Y represents a group capable of releasing a radical containing no aryl group.
<8>
<7> The resin according to the above <7>, wherein the chain transfer agent represented by the general formula (II) is represented by the general formula (II ′).

In general formula (II ′),
A ₁ and A ₂ each independently represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group.
<9>
The manufacturing process of the resin (B)
The resin according to any one of <1> to <8> above, which comprises a step of sequentially adding a radical generator when the terminal structure represented by the general formula (III) is replaced with a radical generator. .

In general formula (III),
A represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group.
<10>
A positive resist composition comprising (A) a compound that generates an acid upon irradiation with actinic rays or radiation, and (B) the resin according to any one of <1> to <9> above. <11>
The positive resist composition as described in <10> above, further comprising a basic compound.
<12>
A pattern forming method comprising the steps of: forming a film from the positive resist composition according to <10> or <11>, and exposing and developing the film.

  By using the polymer of the present invention, a positive resist composition with improved LER (line edge roughness), pattern collapse, and development defects even in the formation of a fine pattern of 100 nm or less, and a pattern forming method using the same And a polymer used therefor can be provided.

Hereinafter, the best mode for carrying out the present invention will be described.
In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what does not have a substituent and what has 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). Further, “the number of carbon atoms of a certain functional group” represents the total number of carbon atoms of the functional group excluding the carbon number of the substituent.

(B) Resin The resin (B) of the present invention contains the repeating unit (a) represented by the general formula (I) and is produced by living radical polymerization, and is alkali-soluble by the action of an acid. It becomes resin.

In general formula (I),
X _a1 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R represents a group capable of decomposing and leaving by the action of an acid containing a monocyclic alicyclic group.

The repeating unit (a) will be described in detail.
Examples of the alkyl group of Xa ₁ include a linear alkyl group and a branched alkyl group, and include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group. Those having 1 to 4 carbon atoms are preferred. The alkyl group of Xa ₁ may be substituted with a halogen atom, a hydroxyl group or the like.
R represents a group capable of decomposing and leaving by the action of an acid containing a monocyclic alicyclic group.
Examples of the group capable of decomposing by the action of an acid include —C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), —C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), and the like. Can do. In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
The acid-decomposable group is preferably a cumyl ester group, an enol ester group, an acetal ester group, a tertiary alkyl ester group or the like. More preferably, it is a tertiary alkyl ester group.

  The repeating unit (a) is preferably a repeating unit represented by the general formula (Ia) and the general formula (Ib).

In the general formula _{(Ia), X a1} has the same meaning as _{X a1} in the formula (I).
R ₁ , R ₂ and R ₃ each independently represents an alkyl group or a monocyclic alicyclic group. However, at least one of R ₁ , R ₂ and R ₃ is a monocyclic alicyclic group.

In general formula (Ib),
X _a1 has the same meaning as _{X a1} in the formula (I).
R ₄ represents an alkyl group and a cycloalkyl group.
R ₅ represents an atomic group necessary for forming a monocyclic alicyclic group together with a carbon atom.

Examples of the alkyl group represented by R _{1 to} R ₄ include a linear alkyl group and a branched alkyl group, and include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, t -A C1-C4 thing, such as a butyl group, is preferable.
Examples of the monocyclic alicyclic group represented by R _{1 to} R ₃ include a cycloalkyl group having 3 to 15 carbon atoms, a cycloalkenyl group having 3 to 15 carbon atoms, and these methylene groups as other hetero atoms (oxygen atoms, sulfur atoms, etc. ). In particular, a cycloalkyl group having 4 to 10 carbon atoms such as a cyclopentyl group and a cyclohexyl group is preferable.
Examples of the cycloalkyl group represented by R ₄ include a cycloalkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 6 carbon atoms is preferable. Examples of R ₅ include alkylene groups having 2 to 15 carbon atoms and groups in which these methylene groups are substituted with other heteroatoms (oxygen atoms, sulfur atoms, etc.), and in particular, — (CH ₂ ) ₄ —, — (CH ₂ ) C3-C10 alkylene groups, such as _5-, are preferable.
R _{1 to} R ₅ may further have a substituent such as an alkyl group, an alkoxycarbonyl group, or an alkoxy group.

  LER is improved by having the acid-decomposable groups represented by the general formulas (Ia) and (Ib), but the pattern collapse performance is improved particularly by having the acid-decomposable group represented by (Ia). To do.

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

  As for content of a repeating unit (a), 15-60 mol% is preferable with respect to all the repeating units in resin (B), More preferably, it is 20-50 mol%, More preferably, it is 30-50 mol%.

  The resin (B) of the present invention preferably further contains a repeating unit (b) having a structure different from that of the repeating unit (a) represented by the general formula (I ′).

In general formula (I ′),
X _a2 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R ′ represents a group capable of decomposing by the action of an acid.
However, when Xa ₁ = Xa ₂ , R ≠ R ′, and when R = R ′, Xa ₁ ≠ Xa ₂ .

  R ′ is preferably a structure selected from (pI) to (pV).

In general formulas (pI) to (pV),
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.
Z represents an atomic group necessary for forming an alicyclic group together with a carbon atom.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or alicyclic group having 1 to 4 carbon atoms. However, at least one of R _{12 to} R ₁₄ , or any of R ₁₅ and R ₁₆ represents an alicyclic 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 group. However, at least one of R _{17 to} R ₂₁ represents an alicyclic group. Further, either R ₁₉ or R ₂₁ represents a linear or branched alkyl group or alicyclic group having 1 to 4 carbon atoms.
R _{22 to} R ₂₅ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic group. However, at least one of R _{22 to} R ₂₅ represents an alicyclic group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

The alicyclic group in R _{11 to} R ₂₅ or the alicyclic 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 cycloalkyl groups may have a substituent.

  Preferred alicyclic groups include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, A cyclodecanyl group, a cyclododecanyl group, etc. can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group.

  As further substituents for these alkyl groups and alicyclic groups, alkyl groups (1 to 4 carbon atoms), halogen atoms, hydroxyl groups, alkoxy groups (1 to 4 carbon atoms), carboxyl groups, alkoxycarbonyl groups (carbon numbers) 2-6). Examples of the substituent that the alkyl group, alkoxy group, alkoxycarbonyl group and the like may further have include a hydroxyl group, a halogen atom, and an alkoxy group.

  Specific examples of the repeating unit (b) are shown below, but the present invention is not limited thereto.

  In particular, the repeating unit (b) is preferably an acid-decomposable repeating unit containing a polycyclic alicyclic group. Thereby, the pattern collapse performance is further improved.

  As for content of a repeating unit (b), 1-60 mol% is preferable with respect to all the repeating units in resin (B), More preferably, it is 3-50 mol%, More preferably, it is 5-40 mol%.

  The acid-decomposable resin of the present invention preferably further has a repeating unit (c) having a lactone group. As the lactone group, any group having a lactone structure can be used, but a group having a 5- to 7-membered ring lactone structure is preferred, and a bicyclo structure or spiro is added to the 5- to 7-membered ring lactone structure. Those in which other ring structures are condensed to form a structure are preferred. It is more preferable to have a repeating unit having a group having a lactone structure represented by any of the following general formulas (LC1-1) to (LC1-16). Further, a group having a lactone structure may be directly bonded to the main chain. Preferred lactone structures are (LC1-1), (LC1-4), (LC1-5), (LC1-6), (LC1-13), (LC1-14), and a specific lactone structure is used. This improves line edge roughness and development defects.

The lactone structure moiety may or may not have a substituent (Rb ₂ ). Preferred substituents (Rb ₂ ) include an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 4 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 1 to 8 carbon atoms, and a carboxyl group. , Halogen atom, hydroxyl group, cyano group, acid-decomposable group and the like. n2 represents an integer of 0 to 4. When n2 is 2 or more, a plurality of (Rb ₂ ) may be the same or different, and a plurality of (Rb ₂ ) may be bonded to form a ring.

  Examples of the repeating unit having a group having a lactone structure represented by any of the general formulas (LC1-1) to (LC1-16) include a repeating unit represented by the following general formula (AI).

In general formula (AI),
Rb ₀ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Preferable substituents that the alkyl group of Rb ₀ may have include a hydroxyl group and a halogen atom. Examples of the halogen atom for Rb ₀ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Rb ₀ is preferably a hydrogen atom or a methyl group.
Ab represents a single bond, an alkylene group, a divalent linking group having a monocyclic or polycyclic alicyclic hydrocarbon structure, an ether group, an ester group, a carbonyl group, a carboxyl group, or a divalent group obtained by combining these. To express. A linking group represented by a single bond or —Ab ₁ —CO ₂ — is preferable. Ab ₁ represents a linear or branched alkylene group or a monocyclic or polycyclic cycloalkylene group, preferably a methylene group, an ethylene group, a cyclohexyl group, an adamantyl group, or a norbornyl group.
V represents a group having a structure represented by any one of the general formulas (LC1-1) to (LC1-16).

  The repeating unit having a lactone structure usually has an optical isomer, but any optical isomer may be used. One optical isomer may be used alone, or a plurality of optical isomers may be mixed and used. When one kind of optical isomer is mainly used, the optical purity (ee) thereof is preferably 90 or more, more preferably 95 or more.

  The content of the repeating unit (C) having a lactone structure is preferably from 15 to 60 mol%, more preferably from 20 to 50 mol%, still more preferably from 30 to 50 mol%, based on all repeating units in the resin (B). .

  Specific examples of the repeating unit having a group having a lactone structure are given below, but the present invention is not limited thereto.

  Particularly preferred repeating units having a lactone group include the following repeating units. By selecting the optimum lactone structure, the pattern profile and the density dependence become good.

The resin (B) of the present invention preferably further contains a repeating unit having a polar group.
The repeating unit having a polar group is preferably a repeating unit having an alicyclic hydrocarbon structure substituted with a polar group. This improves the substrate adhesion and developer compatibility.
The alicyclic hydrocarbon structure of the alicyclic hydrocarbon structure substituted with a polar group is preferably an adamantyl group, a diamantyl group, or a norbornane group. The polar group is preferably a hydroxyl group or a cyano group. As the alicyclic hydrocarbon structure substituted with a preferable polar group, partial structures represented by the following general formulas (VIIa) to (VIId) are preferable.

In general formulas (VIIa) to (VIIc),
R ₂ c to R ₄ c each independently represents a hydrogen atom, a hydroxyl group or a cyano group. However, at least one of R ₂ c to R ₄ c represents a hydroxyl group or a cyano group. Preferably, one or two of R ₂ c to R ₄ c are a hydroxyl group and the rest are hydrogen atoms. In general formula (VIIa), it is more preferable that _two of R ₂ c to R ₄ c are a hydroxyl group and the remaining is a hydrogen atom.

  Examples of the repeating unit having groups represented by general formulas (VIIa) to (VIId) include the repeating units represented by the following general formulas (AIIa) to (AIId).

In general formulas (AIIa) to (AIId),
R ₁ c represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.
R ₂ c to R ₄ c each independently represents a hydrogen atom, a hydroxyl group or a cyano group. However, at least one of R ₂ c to R ₄ c represents a hydroxyl group or a cyano group. R ₂ c to R ₄ c is a general formula (VIIa) ~ same meanings as in R ₂ c to R ₄ c to (VIIc). ,

  The content of the repeating unit having an alicyclic hydrocarbon structure substituted with a polar group is preferably 5 to 40 mol%, more preferably 5 to 30 mol%, still more preferably 10 to 25 mol based on all repeating units in the polymer. %.

  Specific examples of the repeating unit having a structure represented by the general formulas (AIIa) to (AIIb) are given below, but the present invention is not limited thereto.

  The resin (B) of the present invention can further have a repeating unit containing an alicyclic structure that is not substantially decomposed by an acid. Thereby, pattern collapse performance, pattern shape, and dry etching resistance are improved. Here, “substantially not decomposed by an acid” means that the decomposition rate during pattern formation described later is less than 1%. Examples of alicyclic structures that are not substantially decomposed by an acid include monocyclic alicyclic structures such as cyclopentyl, cyclohexyl, and cyclododecyl, bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, and tricyclo. [5.2.1.02,6] decane, tetracyclo [4.4.0.12, 6.17,10] dodecane, tetracyclo [6.2.13,6.02,7] decane, deca Examples thereof include polycyclic alicyclic structures such as hydronaphthalene. These alicyclic structures may have a substituent, and examples thereof include an alkyl group having 1 to 10 carbon atoms and a halogen atom.

The resin (B) of the present invention can further have a repeating unit containing a non-acid-decomposable alicyclic group. Thereby, pattern collapse performance, pattern shape, and dry etching resistance are improved. Non-acid-decomposable alicyclic groups include monocyclic alicyclic groups such as cyclopentyl, cyclohexyl and cyclododecyl, bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane and tricyclo [5. 2.1.0 ^2,6 ] decane, tetracyclo [4.4.0.1 ^2,6 . 1 ^7,10 ] dodecane, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] decane, decahydronaphthalene, and other polycyclic alicyclic groups. These alicyclic groups may have a substituent, and examples thereof include an alkyl group having 1 to 10 carbon atoms and a halogen atom.

  The content of the repeating unit containing a non-acid-decomposable alicyclic group is preferably from 1 to 40 mol%, more preferably from 3 to 30 mol%, still more preferably from 5 to 20 mol%, based on all repeating units in the polymer. .

  Specific examples of the repeating unit containing a non-acid-decomposable alicyclic group are shown below, but the present invention is not limited thereto.

  The acid-decomposable resin of the present invention can have a repeating unit having an alkali-soluble group. Examples of the alkali-soluble group include a carboxyl group, a sulfonamide group, a sulfonylimide group, a bisulsulfonylimide group, and an aliphatic alcohol in which the α-position is substituted with an electron withdrawing group, and has a repeating unit having a carboxyl group. Is more preferable. By having a repeating unit having an alkali-soluble group, the resolution in contact hole applications is increased. The repeating unit having an alkali-soluble group includes a repeating unit in which an alkali-soluble group is directly bonded to the main chain of the resin, such as a repeating unit of acrylic acid or methacrylic acid, or an alkali in the main chain of the resin through a linking group. Either a repeating unit to which a soluble group is bonded, or a polymerization initiator or chain transfer agent having an alkali-soluble group is used at the time of polymerization and introduced at the end of the polymer chain, and the linking group is monocyclic or polycyclic. It may have a cyclic hydrocarbon structure. Particularly preferred are repeating units of acrylic acid or methacrylic acid.

  As for content of the repeating unit which has an alkali-soluble group, 1-20 mol% is preferable with respect to all the repeating units in a polymer, More preferably, it is 3-15 mol%, More preferably, it is 5-10 mol%.

  Specific examples of the repeating unit having an alkali-soluble group are shown below, but the present invention is not limited thereto.

  In addition to the above repeating structural units, acid-decomposable resins adjust dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and general required properties of resist, such as resolution, heat resistance, and sensitivity. For this purpose, various repeating structural units can be included.

  Examples of such repeating structural units include, but are not limited to, repeating structural units corresponding to the following monomers.

Thereby, the performance required for the acid-decomposable resin, in particular,
(1) Solubility in coating solvent,
(2) Film formability (glass transition point),
(3) Alkali developability,
(4) Membrane slip (hydrophobic, alkali-soluble group selection),
(5) Adhesion of unexposed part to substrate,
(6) Dry etching resistance,
Etc. can be finely adjusted.

  As such a monomer, for example, a compound having one addition polymerizable unsaturated bond selected from acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, etc. Etc.

  In addition, any addition-polymerizable unsaturated compound that can be copolymerized with monomers corresponding to the above various repeating structural units may be copolymerized.

  In acid-decomposable resins, the molar ratio of each repeating structural unit is the resist dry etch resistance, standard developer suitability, substrate adhesion, resist profile, and general resist performance required for resolving power, heat resistance, and sensitivity. It is set appropriately in order to adjust etc.

  When the composition of the present invention is for ArF exposure, the resin preferably has no aromatic group from the viewpoint of transparency to ArF light.

  The acid-decomposable resin is preferably one in which all of the repeating units are composed of (meth) acrylate-based repeating units. In this case, all of the repeating units may be methacrylate repeating units, all of the repeating units may be acrylate repeating units, or a mixture of methacrylate repeating units / acrylate repeating units, but all of the acrylate repeating units may be used. It is preferable that it is 50 mol% or less of a repeating unit.

  More preferably, the acid-decomposable resin is substituted with 20 to 50 mol% of a (meth) acrylate-based repeating unit having an acid-decomposable group, 20 to 50 mol% of a (meth) acrylate-based repeating unit having a lactone structure, and substituted with a polar group. It is a copolymer having 5 to 30 mol% of a (meth) acrylate repeating unit having an alicyclic hydrocarbon structure, or a copolymer having 0 to 20 mol% of another repeating unit.

In the positive resist composition of the present invention, the blending amount of all the acid-decomposable resins according to the present invention in the entire composition is preferably 50 to 99.99% by mass, more preferably 60 to 99, based on the total solid content. 0.0% by mass.
In the present invention, the acid-decomposable resin may be used alone or in combination.

  The resin (B) of the present invention is produced by living radical polymerization. Living radical polymerization refers to radical polymerization in which the growth terminal portion is in a state of radical release / recombination during the polymerization, and apparently the termination reaction does not proceed. Under this condition, the degree of dispersion (ratio of the weight average molecular weight to the number average molecular weight) becomes very small as compared with ordinary radical polymerization. Examples of living radical polymerization include a method using a chain transfer agent, a method of polymerizing in the presence of a metal complex catalyst (transition metal catalyst whose central metal is Fe, Ru, Cu, Ni or the like) and a compound containing a halogen atom. Can be mentioned. Among these, a method using a chain transfer agent is particularly preferable.

  Examples of the chain transfer agent in living radical polymerization using a chain transfer agent include sulfur-containing compounds, nitrogen-containing compounds (such as nitroxyl compounds), and iodine-containing alkyls (for example, 2-iodoperfluoropropane). Among these, in particular, by using a sulfur-containing compound as a chain transfer agent, the degree of dispersion of the resin can be effectively reduced, and the metal content in the resin can be reduced.

  The sulfur-containing compound as the chain transfer agent is preferably a compound represented by the general formula (II). By using this compound, the dispersity of the resin of the present invention can be further effectively reduced, and the transmittance of the resin at 193 nm is improved.

In general formula (II),
A represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group.
Y represents a group capable of releasing a radical containing no aryl group.

The alkyl group in A is an alkyl group having 1 to 20 carbon atoms excluding the carbon number of the substituent (for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, sec -Butyl group, n-octyl group, etc.) are preferable, and an alkyl group having 1 to 10 carbon atoms excluding carbon atoms of the substituent is most preferable. The cycloalkyl group in A is preferably a cycloalkyl group having 3 to 20 carbon atoms (for example, cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, adamantyl, etc.) excluding the carbon number of the monocyclic or polycyclic substituent, and is monocyclic or Most preferred is a cycloalkyl group having 3 to 15 carbon atoms excluding the carbon number of the polycyclic substituent.
The aryl group in A is preferably an aryl group having 6 to 30 carbon atoms (for example, phenyl, naphthyl, anthranyl, etc.) excluding a substituent, and most preferably an aryl group having 6 to 18 carbon atoms.
Examples of the heterocyclic group in A include C3-C30, 5- to 7-membered, saturated or unsaturated, aromatic or non-aromatic, monocyclic or condensed heterocyclic group, more preferably The ring-constituting atom is selected from a carbon atom, a nitrogen atom and a sulfur atom, and is a heterocyclic group having at least one heteroatom of any one of a nitrogen atom, an oxygen atom and a sulfur atom, more preferably 3 to 30 carbon atoms. And a 5- or 6-membered aromatic heterocyclic group. Examples of the heterocyclic group include 2-furyl, 2-thienyl, 2-pyridyl, 4-pyridyl, 2-pyrimidinyl, 2-benzothiazolyl, pyrrol-1-yl, imidazol-1-yl, pyrazol-1-yl, 1,2,3-triazol-1-yl, 1,2,4-triazol-1-yl, 1,2,4-triazol-4-yl, indol-1-yl and the like are included.

  Each substituent of A may further have a substituent, and examples of the substituent that may further include an alkyl group, a cycloalkyl group, a halogen atom, an alkoxy group, an alkoxycarbonyl group, and a cyano group. It is done.

  Y represents a group capable of releasing a radical containing no aryl group. The group capable of releasing a radical is a group that can be released from the general formula (II) after the free radical (R) and the compound represented by the general formula (II) have reacted as described below. Means that. In Y, the atom bonded to sulfur is preferably a tertiary carbon atom or a sulfur atom. Y is preferably a group in which atoms bonded to a sulfur atom are a tertiary carbon atom and a sulfur atom.

  The chain transfer agent represented by the general formula (II) is most preferably a bis (thiocarbonyl) sulfide represented by the general formula (II ').

In General Formula (II ′), A ₁ and A ₂ each independently represent a group selected from A in General Formula (II).

  By using the compound represented by the general formula (II '), it becomes possible to most efficiently reduce the degree of dispersion of the resin. Thereby, the LER can be further reduced. In addition, the compound represented by the general formula (II ′) is very easy to synthesize compared to other chain transfer agents (for example, dithioesters), and is generally solid and easy to handle. There are advantages such as.

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

  As a method for synthesizing the compound represented by the general formula (II) such as dithioester and bis (thiocarbonyl) disulfide, a known method can be used. In other words, a method of synthesizing dithiocarboxylic acid by reacting a nucleophile with carbon disulfide and then synthesizing a dithioester by reacting with an alkylating agent (Method 1), and reacting dithiocarboxylic acid with an oxidizing agent to bis Examples include a method (method 2) in which (thiocarbonyl) disulfide is synthesized and reacted with a polymerization initiator to synthesize a dithioester.

  The living radical polymerization using the chain transfer agent of the general formula (II) will be described. As a polymerization method, polymerization is performed by heating a solution containing a monomer, a polymerization initiator, and a chain transfer agent of the general formula (II) (batch polymerization), and adding a solution containing the monomer to the heated solution. Although there is a method (drop polymerization), the drop polymerization method is preferable from the viewpoint of production stability. A monomer, a polymerization initiator, and a chain transfer agent may be added separately to the reaction system, or may be mixed and added. When adding separately to a reaction system, each addition time may be the same and may differ. Furthermore, it is also possible to add by shifting the addition start time. In the present invention, the reaction system may be the reaction solvent itself, or may be a reaction solvent in which a part selected from a monomer, a polymerization initiator, and a chain transfer agent is added in advance. That is, in the present invention, the reaction solvent itself may be used as a reaction system, and the monomer may be polymerized while adding a monomer, a polymerization initiator, and a chain transfer agent thereto, or the monomer, the polymerization initiator, A part selected from a chain transfer agent may be added in advance to form a reaction system, and the monomer may be polymerized while the remaining monomer, polymerization initiator and chain transfer agent are added thereto. In particular, it is preferable to add the remaining monomer and polymerization initiator to the reaction system to which the total amount of chain transfer agent used, and in some cases, a monomer and a part of the polymerization initiator are added. When adding a monomer, a polymerization initiator, and a chain transfer agent, it is preferable to dissolve in a reaction solvent and add as a solution. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane and diisopropyl ether, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, dimethylformamide, dimethylacetamide An amide solvent such as N-methylpyrrolidinone, and a solvent that dissolves the composition of the present invention such as propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether described later. These solvents may be used alone or in combination. More preferably, the polymerization is performed using the same solvent as that used in the resist composition of the present invention. The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon.

  As the polymerization initiator, commercially available radical initiators (azo initiators, peroxides, etc.) can be used. As the radical initiator, an azo initiator is preferable, and an azo initiator having an ester group, a cyano group, or a carboxyl group is preferable. Preferred polymerization initiators include azobisisobutyronitrile, azobisdimethylvaleronitrile, dimethyl 2,2′-azobis (2-methylpropionate) and the like. The polymerization initiators may be used alone or in combination.

  As the monomer, a monomer corresponding to the repeating unit of the polymer to be produced is used. For example, when the polymer to be produced is the acid-decomposable resin, a monomer corresponding to the repeating unit of the acid-decomposable resin to be produced is used.

After completion of the reaction, it is put into a solvent and a desired polymer is recovered by a method such as powder or solid recovery. The concentration of the reaction is 5 to 50% by mass, preferably 10 to 30% by mass. The reaction temperature depends on the decomposition efficiency of the radical initiator used, so it is difficult to determine it uniquely. However, if it is too low, the monomer conversion rate will be low and the reaction time will be long. Therefore, it is preferable that the initiator to be used has a half-life temperature of 10 hours or more and 10 minutes or less, and more preferably 9 hours or more and 20 minutes or less. For example, when azobisisobutyronitrile is used as an initiator, the reaction temperature is preferably 50 ° C. or higher and 100 ° C. or lower, and most preferably 60 ° C. or higher and 90 ° C. or lower. If the amount of the polymerization initiator used is too low for the chain transfer agent, the reaction rate becomes extremely slow, and if it is too high, it becomes difficult to control the polymerization reaction. It is preferably used in an amount of 10.0 molar equivalents or less, and most preferably 0.20 molar equivalents or more and 5.0 molar equivalents or less. Chain transfer agents may be used alone or in combination. The amount of chain transfer agent used depends on the target of the number average molecular weight of the polymer and cannot be determined uniquely, but is approximately 0.01 molar equivalent or more and 50.0 molar equivalent or less with respect to the number of moles of all monomers. Is preferably 0.1 molar equivalent or more and 20.0 molar equivalent or less.
The weight average molecular weight of the polymer according to the present invention is preferably 1,000 to 200,000, more preferably 3,000 to 20,000, and most preferably 5,000 to as a polystyrene-converted value by the GPC method. 15,000. By setting the weight average molecular weight to 1,000 to 200,000, deterioration of heat resistance and dry etching resistance can be prevented, developability is deteriorated, and viscosity is increased, resulting in deterioration of film forming property. Can be prevented.
The degree of dispersion (molecular weight distribution) of the polymer obtained by the polymerization method of the present invention is lower than that of a normal radical polymer. Thereby, the resolution and the resist shape are excellent, the side wall of the resist pattern is smooth, and the roughness property is excellent. The degree of dispersion of the polymer of the present invention is from 1.0 to less than 1.50, preferably from 1.0 to less than 1.30, and more preferably from 1.0 to less than 1.20. The smaller the molecular weight distribution, the smoother the sidewall of the resist pattern and the better the roughness.

  In the polymer obtained by the polymerization method of the present invention, the substituent (dithioester group) derived from the chain transfer agent represented by the general formula (III) may remain at the terminal.

  In general formula (III), A is synonymous with A in general formula (II).

If this polymer is used as a resist material as it is, the transmittance is poor and the pattern shape may be deteriorated. Therefore, it is preferable to remove the dithioester group derived from the chain transfer agent.
As a removal method, there is a method in which a radical generator and, if necessary, a chain transfer agent (thiol, disulfide, etc.) are added and replaced after completion of polymerization. At this time, a method of adding a radical generator to the reaction solution at the end of the polymerization and replacing it, and a method of isolating the polymer after the completion of the polymerization and again dissolving the polymer in a solvent and then adding the radical generator are mentioned. However, from the viewpoint of efficiency, a method of adding a radical generator to the reaction solution at the end of the polymerization for substitution is preferable. As the radical generator, those mentioned as the radical initiator can be used. The radical generator may be the same as or different from the radical initiator used during the polymerization. The amount of the radical generator used is preferably 1.0 mole equivalent or more and 20.0 mole equivalent or less, and 2.0 mole equivalent or more and 10.0 mole relative to the chain transfer agent of the general formula (I) used in the polymerization. It is particularly preferable to use an equivalent amount or less. The reaction temperature is preferably in the range mentioned in the previous polymerization temperature. As a method for adding the radical generator, there are a method of batch addition, a method of adding in a divided manner, and a method of adding dropwise as a solution, but a method of adding in a divided manner and adding dropwise is preferred for safety.

  The positive resist composition containing the resin of the present invention will be described in detail below.

The positive resist composition of the present invention contains the resin (B) produced by the living radical polymerization. (B) As for the compounding quantity in the whole composition of resin of a component, 50-99.99 mass% is preferable in a total solid, More preferably, it is 60-99.0 mass%.
In the present invention, the resin of component (B) may be used alone or in combination.

(A) Acid generator The positive resist composition of the present invention contains a compound (A) that generates an acid upon irradiation with actinic rays or radiation (hereinafter also referred to as “photo acid generator”).
Examples of such photoacid generators include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, actinic rays used in microresists, etc. Known compounds that generate an acid upon irradiation with radiation and mixtures thereof can be appropriately selected and used.

  Examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

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

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

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, compounds represented by the following general formula (ZI), (ZII) or (ZIII) can be exemplified.

In general formula (ZI):
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
X ⁻ represents a non-nucleophilic anion, preferably sulfonate anion, carboxylate anion, bis (alkylsulfonyl) amide anion, tris (alkylsulfonyl) methide anion, BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^{— and the} like. An organic anion having a carbon atom is preferable.

  Preferred organic anions include organic anions represented by the following general formulas (AN1) to (AN4).

In general formulas (AN1) and (AN2):
Rc ₁ represents an organic group.

Formula (AN1) ~ (AN2), examples of the organic group in Rc _1, include those having 1 to 30 carbon atoms, preferably an alkyl group which may be substituted, cycloalkyl group, aryl group, or a mixture, A group in which a plurality of them are linked by a linking group such as a single bond, —O—, —CO ₂ —, —S—, —SO ₃ —, —SO ₂ N (Rd ₁ ) — can be exemplified. Rd ₁ represents a hydrogen atom or an alkyl group, and may form a ring structure with a bonded alkyl group, cycloalkyl group, or aryl group.
More preferred as the organic group for Rc ₁ is an alkyl group substituted at the 1-position with a fluorine atom or a fluoroalkyl group, or a phenyl group substituted with a fluorine atom or a fluoroalkyl group. By having a fluorine atom or a fluoroalkyl group, the acidity of the acid generated by light irradiation is increased and the sensitivity is improved. When Rc ₁ has 5 or more carbon atoms, it is preferable that at least one carbon atom has a hydrogen atom, not all hydrogen atoms are substituted with fluorine atoms, and the number of hydrogen atoms is fluorine. More preferably than atoms. By not having a perfluoroalkyl group having 5 or more carbon atoms, ecotoxicity is reduced.

As a particularly preferred embodiment of Rc ₁ , groups represented by the following general formula can be exemplified.

In the above general formula,
Rc ₆ is substituted with a perfluoroalkylene group having 4 or less carbon atoms, more preferably 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms, 1 to 4 fluorine atoms and / or 1 to 3 fluoroalkyl groups. Represents a phenylene group.
Ax represents a single bond or a divalent linking group (preferably —O—, —CO ₂ —, —S—, —SO ₃ —, —SO ₂ N (Rd ₁ ) —). Rd ₁ represents a hydrogen atom or an alkyl group, and may combine with Rc ₇ to form a ring structure.
Rc ₇ represents a hydrogen atom, a fluorine atom, a linear or branched, monocyclic or polycyclic cycloalkyl group or aryl group which may be substituted. The optionally substituted alkyl group, cycloalkyl group and aryl group preferably do not have a fluorine atom as a substituent.

In the general formulas (AN3) and (AN4),
Rc ₃ , Rc ₄ and Rc ₅ each independently represents an organic group.
Rc ₃ and Rc ₄ may combine to form a ring.

In the general formulas (AN3) and (AN4), the organic groups represented by Rc ₃ , Rc ₄ and Rc ₅ are preferably the same as the preferred organic groups in Rc ₁ .
When Rc ₃ and Rc ₄ are combined to form a ring, examples of the group formed by combining Rc ₃ and Rc ₄ include an alkylene group and an arylene group. A perfluoroalkylene group having 2 to 4 carbon atoms is preferred. By combining Rc ₃ and Rc ₄ to form a ring, the acidity of the acid generated by light irradiation is increased, and the sensitivity is improved, which is preferable.

In the general formula (ZI), the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
Two members out of R _{201 to} R ₂₀₃ may combine to form a ring structure, and the ring may contain 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 (ZI-1), (ZI-2) and (ZI-3) described later.

In addition, the compound which has two or more structures represented by general formula (Z1) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (ZI) is, at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (ZI) It may be a compound.

  Further preferred examples of the component (Z1) include compounds (ZI-1), (ZI-2) and (ZI-3) described below.

The compound (ZI-1) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (ZI), arylsulfonium compound, i.e., a compound having arylsulfonium as a cation.
In the arylsulfonium compound, all of R _{201 to} R ₂₀₃ may be an aryl group, or a part of R _{201 to} R ₂₀₃ may be an aryl group, and the rest may be an alkyl group or a cycloalkyl group.
Examples of the arylsulfonium compound include triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, aryldicycloalkylsulfonium compounds, and the like.
The aryl group of the arylsulfonium compound is preferably an aryl group such as a phenyl group or a naphthyl group, or a heteroaryl group such as an indole residue or a pyrrole residue, more preferably a phenyl group or an indole residue. 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, and more preferably , An alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (ZI-2) will be described.
The compound (ZI-2) is, R ₂₀₁ to R ₂₀₃ in formula (ZI) each independently is a compound when it represents an organic group having no aromatic ring. 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, branched, cyclic 2-oxoalkyl group, an alkoxycarbonylmethyl group, particularly A linear or branched 2-oxoalkyl group is preferred.

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 10 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, more preferably an alkoxymethyl group.
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 2-oxoalkyl group as R _{201 to} R ₂₀₃ may be linear, branched or cyclic, and preferably a group having> C═O at the 2-position of the above alkyl group or cycloalkyl group Can be mentioned.
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), a hydroxyl group, a cyano group, or a nitro group.

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

In general formula (ZI-3),
R ₁ c to R ₅ c each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, or a halogen atom.
R ₆ c and R ₇ c each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
Rx and Ry each independently represents an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group.
R ₁ c to R ₇ Any two or more of c, and Rx and Ry may combine with each other to form a ring structure, the ring structure may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond May be included. R ₁ c to R ₇ Any two or more of c, and as the group Rx and Ry are formed by combined include a butylene group and a pentylene group.
X − represents a non-nucleophilic anion and is the same as X ^{− in} the general formula (ZI).

The alkyl group as R ₁ c to R ₇ c may be either linear or branched, for example, an alkyl group having 1 to 20 carbon atoms, preferably a linear chain having 1 to 12 carbon atoms and A branched alkyl group (for example, a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, a linear or branched pentyl group) can be exemplified.
Preferable examples of the cycloalkyl group as R ₁ c to R ₇ c include a cycloalkyl group having 3 to 8 carbon atoms (for example, a cyclopentyl group and a cyclohexyl group).
The alkoxy group as R ₁ c to R ₅ c may be linear, branched or cyclic, for example, an alkoxy group having 1 to 10 carbon atoms, preferably a linear or branched chain having 1 to 5 carbon atoms. Alkoxy groups (for example, methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, linear or branched pentoxy group), cyclic alkoxy groups having 3 to 8 carbon atoms (for example, cyclopentyloxy group, cyclohexyl) Oxy group).
Preferably any of R ₁ c to R ₅ c is a linear or branched alkyl group, a cycloalkyl group or a linear, branched or cyclic alkoxy group, more preferably the R ₁ c to R ₅ c atoms The sum of the numbers is 2-15. Thereby, solvent solubility improves more and generation | occurrence | production of a particle is suppressed at the time of a preservation | save.

The alkyl group as Rx and Ry, there can be mentioned the same alkyl groups as R ₁ c~R ₇ c. The alkyl group as Rx and Ry is more preferably a linear or branched 2-oxoalkyl group or an alkoxymethyl group.
The cycloalkyl group as Rx and Ry may be the same as the cycloalkyl group of R ₁ c~R ₇ c. The cycloalkyl group as Rx and Ry is more preferably a cyclic 2-oxoalkyl group.
Examples of the linear, branched, or cyclic 2-oxoalkyl group include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group as R ₁ c to R ₇ c.
The alkoxy group in the alkoxycarbonylmethyl group may be the same as the alkoxy group as R ₁ c~R ₅ c.
Rx and Ry are preferably alkyl groups having 4 or more carbon atoms, more preferably 6 or more, and still more preferably 8 or more.

In the general formulas (ZII) and (ZIII),
R ₂₀₄ to R ₂₀₇ each independently represents an aryl group, an alkyl group or a cycloalkyl group.
The aryl group of R ₂₀₄ to R _207, a phenyl group, a naphthyl group, more preferably a phenyl group.
The alkyl group as R ₂₀₄ to R ₂₀₇ may be linear, it may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 10 carbon atoms, an ethyl group, a propyl Group, butyl group, pentyl group).
The cycloalkyl group as R ₂₀₄ to R ₂₀₇ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
R ₂₀₄ to R ₂₀₇ may have a substituent. The R ₂₀₄ to R ₂₀₇ are substituents which may have, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (e.g., 6 carbon atoms 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.
X ⁻ represents a non-nucleophilic anion, and examples thereof include the same non-nucleophilic anion as X ^{− in} formula (ZI).

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, compounds represented by the following general formulas (ZIV), (ZV), and (ZVI) can be further exemplified.

In general formulas (ZIV) to (ZVI),
Ar ₃ and Ar ₄ each independently represents an aryl group.
R ₂₀₆ represents an alkyl group, a cycloalkyl group or an aryl group.
_R207 and _R208 each independently represents an alkyl group, a cycloalkyl group, an aryl group, or an electron withdrawing group. R ₂₀₇ is preferably an aryl group. R ₂₀₈ is preferably an electron-withdrawing group, and more preferably a cyano group or a fluoroalkyl group.
A represents an alkylene group, a cycloalkylene group, an alkenylene group or an arylene group.

Among the compounds that generate an acid upon irradiation with actinic rays or radiation, more preferred are compounds represented by the general formulas (ZI) to (ZIII), and still more preferred are compounds represented by (ZI). Even more preferred are compounds represented by (ZI-1) to (ZI-3).
Furthermore, the compound which generate | occur | produces the acid represented by the following general formula (AC1)-(AC3) by irradiation of actinic light or a radiation is preferable.

That is, as a particularly preferred embodiment of the photoacid generator, in the structure represented by the general formula (ZI), X ⁻ is an anion selected from the general formulas (AN1), (AN3), and (AN4). A compound can be mentioned.

  Among the compounds that decompose upon irradiation with actinic rays or radiation to generate an acid, examples of particularly preferable compounds are listed below.

  A photo-acid generator can be used individually by 1 type or in combination of 2 or more types. When two or more types are used in combination, it is preferable to combine two types of compounds that generate two types of organic acids that differ in the total number of atoms excluding hydrogen atoms by two or more.

  The content of the photoacid generator in the composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 based on the total solid content of the positive resist composition. -7% by mass.

Resin having no group decomposable by the action of an acid The positive resist composition of the present invention may contain a resin having no group decomposing by the action of an acid.
“No acid-decomposable group” means that there is no or very little decomposability due to the action of acid in the image forming process in which the positive resist composition of the present invention is usually used. It does not have a group that contributes to image formation. Examples of such a resin include a resin having an alkali-soluble group and a resin having a group that is decomposed by the action of an alkali and improves the solubility in an alkali developer.
As the resin having no group capable of decomposing by the action of an acid, a resin having at least one repeating unit derived from a (meth) acrylic acid derivative and / or an alicyclic olefin derivative is preferable.
Examples of the alkali-soluble group contained in a resin that does not have a group that decomposes by the action of an acid include a carboxyl group, a phenolic hydroxyl group, an aliphatic hydroxyl group substituted at the 1- or 2-position with an electron-attracting group, An amino group substituted with an attractive group (eg, sulfonamide group, sulfonimide group, bissulfonylimide group), a methylene group substituted with an electron withdrawing group, or a methine group (eg, ketone group, ester group) A methylene group and a methine group substituted with two are preferred.
The group that decomposes by the action of an alkali contained in a resin that does not have a group that decomposes by the action of an acid and increases the solubility in an alkali developer is preferably a lactone group or an acid anhydride group, more preferably Lactone group.
The resin that does not have a group capable of decomposing by the action of an acid may have a repeating unit having a functional group other than the above. As the repeating unit having another functional group, an appropriate functional group can be introduced in consideration of dry etching resistance, hydrophilicity / hydrophobicity, interaction property and the like. Other repeating units include structural units having a polar functional group such as a hydroxyl group, a cyano group, a carbonyl group, and an ester group, a repeating unit having a monocyclic or polycyclic hydrocarbon structure, a silicon atom, a halogen atom, and a fluoroalkyl. A repeating unit having a group or a repeating unit having a plurality of these functional groups.

  Although the specific example of resin which does not have the group decomposed | disassembled by the effect | action of a preferable acid is shown below, this invention is not limited to this.

  The addition amount of the resin having no group capable of decomposing by the action of an acid is 0 to 30% by mass, preferably 0 to 20% by mass, and more preferably 0 to 15% by mass with respect to the acid-decomposable resin.

The dissolution control compound having a molecular weight of 3000 or less, having at least one selected from an alkali-soluble group, a hydrophilic group, and an acid-decomposable group. The positive resist composition of the present invention includes an alkali-soluble group, a hydrophilic group, and an acid-decomposable group. A dissolution control compound having a molecular weight of 3000 or less (hereinafter also referred to as “solubility control compound”) having at least one selected may be added.
Examples of the dissolution control compound include a carboxyl group, a sulfonylimide group, a compound having an alkali-soluble group such as a hydroxyl group substituted at the α-position with a fluoroalkyl group, a hydroxyl group, a lactone group, a cyano group, an amide group, a pyrrolidone group, a sulfone group. A compound having a hydrophilic group such as an amide group or a compound containing a group capable of decomposing by the action of an acid to release an alkali-soluble group or a hydrophilic group is preferable. The group capable of decomposing by the action of an acid to release an alkali-soluble group or a hydrophilic group is preferably a group in which a carboxyl group or a hydroxyl group is protected with an acid-decomposable group. In order not to lower the permeability of 220 nm or less as the dissolution control compound, it is preferable to use a compound that does not contain an aromatic ring, or to use a compound having an aromatic ring in an amount of 20 wt% or less based on the solid content of the composition.
Preferred dissolution control compounds include carboxylic acid compounds having an alicyclic hydrocarbon structure such as adamantane (di) carboxylic acid, norbornane carboxylic acid, and cholic acid, or compounds in which the carboxylic acid is protected with an acid-decomposable group, and polyols such as saccharides. Or a compound having its hydroxyl group protected with an acid-decomposable group is preferred.

  The molecular weight of the dissolution controlling compound in the present invention is 3000 or less, preferably 300 to 3000, and more preferably 500 to 2500.

  The addition amount of the dissolution control compound is preferably 3 to 40% by mass, more preferably 5 to 20% by mass, based on the solid content of the positive resist composition.

  Specific examples of the dissolution control compound are shown below, but the present invention is not limited thereto.

Basic Compound The positive resist composition of the present invention may contain a basic compound in order to reduce the change in performance over time from exposure to heating or to control the diffusibility of the acid generated by exposure in the film. preferable.

  Examples of basic compounds include nitrogen-containing basic compounds and onium salt compounds. Preferable nitrogen-containing basic compound structures include compounds having partial structures represented by the following general formulas (A) to (E).

In general formula (A),
R ²⁵⁰ , R ²⁵¹ and R ²⁵² are each independently a hydrogen atom, an alkyl having 1 to 20 carbons, a cycloalkyl group having 3 to 20 carbons or an aryl group having 6 to 20 carbons, wherein 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 general formula (E),
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.

  Preferable compounds include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, and piperidine, and may have a substituent. More preferred compounds include compounds having an imidazole structure, diazabicyclo structure, onium hydroxide structure, onium carboxylate structure, trialkylamine structure, aniline structure or pyridine structure, alkylamine derivatives having a hydroxyl group and / or an ether bond, hydroxyl groups and / or Or the aniline derivative which has an ether bond etc. can be mentioned.

  Examples of the compound having an imidazole structure include imidazole, 2,4,5-triphenylimidazole, benzimidazole, and the like. Examples of the compound having a diazabicyclo structure include 1,4-diazabicyclo [2,2,2] octane, 1,5-diazabicyclo [4,3,0] non-5-ene, and 1,8-diazabicyclo [5,4,0. ] Undec-7-ene. Examples of the compound having an onium hydroxide structure include triarylsulfonium hydroxide, phenacylsulfonium hydroxide, sulfonium hydroxide having a 2-oxoalkyl group, specifically triphenylsulfonium hydroxide, tris (t-butylphenyl) sulfonium. Examples thereof include hydroxide, bis (t-butylphenyl) iodonium hydroxide, phenacylthiophenium hydroxide, and 2-oxopropylthiophenium hydroxide. The compound having an onium carboxylate structure is a compound having an onium hydroxide structure in which the anion moiety is converted to a carboxylate, and examples thereof include acetate, adamantane-1-carboxylate, and perfluoroalkylcarboxylate. Examples of the compound having a trialkylamine structure include tri (n-butyl) amine and tri (n-octyl) amine. Examples of aniline compounds include 2,6-diisopropylaniline and N, N-dimethylaniline. Examples of the alkylamine derivative having a hydroxyl group and / or an ether bond include ethanolamine, diethanolamine, triethanolamine, and tris (methoxyethoxyethyl) amine. Examples of aniline derivatives having a hydroxyl group and / or an ether bond include N, N-bis (hydroxyethyl) aniline.

  These basic compounds are used alone or in combination of two or more. The usage-amount of a basic compound is 0.001-10 mass% normally on the basis of solid content of a positive resist composition, Preferably it is 0.01-5 mass%. In order to obtain a sufficient addition effect, 0.001% by mass or more is preferable, and 10% by mass or less is preferable in terms of sensitivity and developability of the non-exposed area.

Fluorine and / or silicon surfactant The positive resist composition of the present invention further comprises a fluorine and / or silicon surfactant (fluorine surfactant and silicon surfactant, fluorine atom and silicon atom It is preferable to contain either one or two or more surfactants containing both.

  When the positive resist composition of the present invention contains fluorine and / or a silicon-based surfactant, adhesion and development defects are obtained with good sensitivity and resolution when using an exposure light source of 250 nm or less, particularly 220 nm or less. It is possible to provide a resist pattern with less.

  Examples of these fluorine and / or silicon surfactants include, for example, JP-A No. 62-36663, JP-A No. 61-226746, JP-A No. 61-226745, JP-A No. 62-170950, JP 63-34540 A, JP 7-230165 A, JP 8-62834 A, JP 9-54432 A, JP 9-5988 A, JP 2002-277862 A, US Patent Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, 5,824,451 Surfactant can be mentioned, The following commercially available surfactant can also be used as it is.

  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. It 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 link) or poly (block link of oxyethylene and oxypropylene) 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 fluorine and / or silicon 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). It is.

Organic Solvent The positive resist composition of the present invention is used by dissolving the above components in a predetermined organic solvent.

  Examples of the organic solvent that can be used 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 -Dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, etc.

In the present invention, the organic solvent may be used alone or in combination, but it is preferable to use a mixed solvent containing two or more solvents having different functional groups. As a result, the solubility of the material is increased, and not only the generation of particles over time can be suppressed, but also a good pattern profile can be obtained. Preferable functional groups contained in the solvent include ester groups, lactone groups, hydroxyl groups, ketone groups, and carbonate groups. As the mixed solvent having different functional groups, the following mixed solvents (S1) to (S5) are preferable.
(S1) a mixed solvent obtained by mixing a solvent containing a hydroxyl group and a solvent not containing a hydroxyl group,
(S2) a mixed solvent obtained by mixing a solvent having an ester structure and a solvent having a ketone structure;
(S3) a mixed solvent obtained by mixing a solvent having an ester structure and a solvent having a lactone structure;
(S4) a mixed solvent obtained by mixing a solvent having an ester structure, a solvent having a lactone structure, and a solvent containing a hydroxyl group;
(S5) A mixed solvent containing a solvent having an ester structure, a solvent having a carbonate structure, and a solvent having a hydroxyl group.
As a result, the generation of particles during storage of the resist solution can be reduced, and the generation of defects during application can be suppressed.

  Examples of the solvent containing a hydroxyl group include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethyl lactate, and the like. And propylene glycol monomethyl ether and ethyl lactate are more preferred.

  Examples of the solvent not containing a hydroxyl group include propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone, butyl acetate, N-methylpyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide and the like. Among these, propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone, and butyl acetate are more preferable, and propylene glycol monomethyl ether acetate, ethyl ethoxypropionate. 2-heptanone and cyclohexanone are particularly preferred.

Examples of the solvent having a ketone structure include cyclohexanone and 2-heptanone, and cyclohexanone is preferable.
Examples of the solvent having an ester structure include propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, and butyl acetate, and propylene glycol monomethyl ether acetate is preferable.
Examples of the solvent having a lactone structure include γ-butyrolactone.
Examples of the solvent having a carbonate structure include propylene carbonate and ethylene carbonate, with propylene carbonate being preferred.

The mixing ratio (mass) of the solvent containing a hydroxyl group and the solvent not containing a hydroxyl group is 1/99 to 99/1, preferably 10/90 to 90/10, more preferably 20/80 to 60/40. . A mixed solvent containing 50% by mass or more of a solvent not containing a hydroxyl group is particularly preferred from the viewpoint of coating uniformity.
The mixing ratio (mass) of the solvent having an ester structure and the solvent having a ketone structure is 1/99 to 99/1, preferably 10/90 to 90/10, and more preferably 40/60 to 80/20. . A mixed solvent containing 50% by mass or more of a solvent having an ester structure is particularly preferable from the viewpoint of coating uniformity.
The mixing ratio (mass) of the solvent having an ester structure and the solvent having a lactone structure is 70/30 to 99/1, preferably 80/20 to 99/1, and more preferably 90/10 to 99/1. . A mixed solvent containing 70% by mass or more of a solvent having an ester structure is particularly preferable from the viewpoint of stability over time.
When mixing a solvent having an ester structure, a solvent having a lactone structure, and a solvent containing a hydroxyl group, the solvent having an ester structure is 30 to 80% by mass, the solvent having a lactone structure is 1 to 20% by mass, and the hydroxyl group is contained. It is preferable to contain 10-60 mass% of solvent to do.
When mixing a solvent having an ester structure, a solvent having a carbonate structure, and a solvent containing a hydroxyl group, the solvent having an ester structure is 30 to 80% by mass, the solvent having a carbonate structure is 1 to 20% by mass, and the hydroxyl group is contained. It is preferable to contain 10-60 mass% of solvent to do.

A preferable embodiment of these solvents is a solvent containing an alkylene glycol monoalkyl ether carboxylate (preferably propylene glycol monomethyl ether acetate), more preferably a mixed solvent of an alkylene glycol monoalkyl ether carboxylate and another solvent, The other solvent is at least one selected from a functional group selected from a hydroxyl group, a ketone group, a lactone group, an ester group, an ether group and a carbonate group, or a solvent having a plurality of these functional groups. A particularly preferable mixed solvent is a mixed solvent of at least one selected from ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether, butyl acetate, and cyclohexanone and propylene glycol monomethyl ether acetate.
The development defect performance can be improved by selecting an optimum solvent.

<Other additives>
The positive resist composition of the present invention further promotes solubility in dyes, plasticizers, surfactants other than the fluorine and / or silicon surfactants, photosensitizers, and developers as necessary. The compound to be made can be contained.

  The dissolution accelerating compound for the developer that can be used in the present invention is a low molecular weight compound having a molecular weight of 1,000 or less and having two or more phenolic OH groups or one or more carboxy groups. When it has a carboxy group, an alicyclic or aliphatic compound is preferable.

  A preferable addition amount of these dissolution promoting compounds is 2 to 50% by mass, and more preferably 5 to 30% by mass with respect to the polymer compound. The amount is preferably 50% by mass or less from the viewpoint of suppressing development residue and preventing pattern deformation during development.

  Such phenolic compounds having a molecular weight of 1000 or less can be obtained by referring to methods described in, for example, JP-A-4-1222938, JP-A-2-28531, U.S. Pat. No. 4,916,210, European Patent 219294, and the like. Can be easily synthesized.

  Specific examples of alicyclic or aliphatic compounds having a carboxyl group include carboxylic acid derivatives having a steroid structure such as cholic acid, deoxycholic acid, lithocholic acid, adamantane carboxylic acid derivatives, adamantane dicarboxylic acid, cyclohexane carboxylic acid, cyclohexane Examples thereof include, but are not limited to, dicarboxylic acids.

  In the present invention, a surfactant other than the fluorine-based and / or silicon-based surfactant may be added. Specifically, nonionic interfaces such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene / polyoxypropylene block copolymers, sorbitan aliphatic esters, polyoxyethylene sorbitan aliphatic esters, etc. Mention may be made of activators.

  These surfactants may be added alone or in some combination.

(Pattern formation method)
The positive resist composition of the present invention is used by dissolving the above components in a predetermined organic solvent, preferably the mixed solvent, filtering the solution, and then applying the solution on a predetermined support as follows. The filter used for filter filtration is preferably made of polytetrafluoroethylene, polyethylene, or nylon of 0.1 microns or less, more preferably 0.05 microns or less, and still more preferably 0.03 microns or less.

For example, a positive resist composition is coated on a substrate (eg, silicon / silicon dioxide coating) used for manufacturing a precision integrated circuit element by an appropriate coating method such as a spinner or a coater, and dried to form a resist film. Form.
The resist film is irradiated with actinic rays or radiation through a predetermined mask, preferably baked (heated), developed and rinsed. Thereby, a good pattern can be obtained.
Exposure (immersion exposure) may be performed by filling a liquid (immersion medium) having a higher refractive index than air between the resist film and the lens during irradiation with actinic rays or radiation. Thereby, resolution can be improved. As the immersion medium to be used, any liquid can be used as long as it has a higher refractive index than air, but pure water is preferred. Further, an overcoat layer may be further provided on the resist film so that the immersion medium and the resist film do not come into direct contact with each other during the immersion exposure. Thereby, elution of the composition from the resist film to the immersion medium is suppressed, and development defects are reduced.

Before forming the resist film, an antireflection film may be coated on the substrate in advance.
As the antireflection film, any of an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, and amorphous silicon, and an organic film type made of a light absorber and a polymer material can be used. 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.

Examples of the actinic ray or radiation include infrared light, visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, etc., but preferably far ultraviolet light having a wavelength of 250 nm or less, more preferably 220 nm or less. Specifically, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (157 nm), X-ray, electron beam, etc. ArF excimer laser, F ₂ excimer laser, EUV (13 nm) An electron beam is preferred.

In the development step, an alkaline developer is used as follows. As an alkaline developer of the resist composition, inorganic hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, primary amines such as ethylamine and n-propylamine, Secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide and the like Alkaline aqueous solutions such as quaternary ammonium salts, cyclic amines such as pyrrole and pihelidine can be used.
Furthermore, alcohols and surfactants can be added in appropriate amounts to the alkaline developer.
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 Next, although an Example is given and this invention is further demonstrated, this invention is not limited to these Examples.

  Synthesis Example 1 (Synthesis of acid-decomposable resin (RA-1))

  Under a nitrogen stream, 5.9 g of cyclohexanone and 0.78 g (2.56 mmol) of the chain transfer agent (II-1) were placed in a three-necked flask and heated to 80 ° C. To this, monomer (1-1) 11.4 g (51.2 mmol), monomer (1-2) 6.0 g (25.6 mmol), monomer (1-3) 10.8 g (51.2 mmol), polymerization start Agent V-60 (azobisisobutyronitrile, Wako Pure Chemical Industries, Ltd.) 0.42 g (2.56 mmol), chain transfer agent (II-1) 0.78 g (2.56 mmol) dissolved in cyclohexanone 106 g Was added dropwise over 6 hours. After completion of dropping, the reaction was further carried out at 80 ° C. for 2 hours. To this solution, a solution prepared by dissolving 3.36 g (10.2 mmol) of a polymerization initiator V-60 (manufactured by Wako Pure Chemical Industries, Ltd.) in 20 mL of cyclohexanone was added dropwise at 80 ° C. over 4 hours and further heated for 2 hours. The reaction solution was allowed to cool and then added dropwise to a mixed solution of 700 m of hexane / 300 ml of ethyl acetate over 20 minutes. The precipitated powder was collected by filtration and dried to obtain 21.4 g of an acid-decomposable resin (RA-1). . The weight average molecular weight of the obtained resin was 6,450 in terms of standard polystyrene, and the dispersity (Mw / Mn) was 1.15.

  Acid-decomposable resins (RA-2) to (RA-36) were synthesized in the same manner as in Synthesis Example 1 according to the conditions in Table 1. The residue of the chain transfer agent contained in the polymer was removed using the initiator used during the polymerization.

Comparative Synthesis Example 1 (Synthesis of acid-decomposable resin (RA-1 ′))
Under a nitrogen stream, 11.8 g of cyclohexanone was placed in a three-necked flask and heated to 80 ° C. To this, monomer (1-1) 11.4 g (51.2 mmol), monomer (1-2) 6.0 g (25.6 mmol), monomer (1-3) 10.8 g (51.2 mmol), polymerization start A solution in which 106 g of cyclohexanone was dissolved in 1.9 g (11.6 mmol) of agent V-60 (azobisisobutyronitrile, manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 6 hours. After completion of dropping, the reaction was further carried out at 80 ° C. for 2 hours. The reaction solution is allowed to cool and then added dropwise over 20 minutes to a mixture of 1400 m of hexane / 600 ml of ethyl acetate. The precipitated powder is collected by filtration and dried to obtain 26.2 g of an acid-decomposable resin (RA-1 ′). It was. The weight average molecular weight of the obtained resin was 6,800 in terms of standard polystyrene, and the dispersity (Mw / Mn) was 1.82.

Comparative Synthesis Example 2 (Synthesis of acid-decomposable resin (RA-1 ″))
Except that the compound represented by the general formula (II ′) is used as the chain transfer agent, the acid-decomposable resin (RA-1 ″) is prepared in the same manner as in Synthesis Example 1 according to the conditions in Table 1. 0.2 g was obtained. The weight average molecular weight of the obtained resin was 6,700 in terms of standard polystyrene, and the dispersity (Mw / Mn) was 1.26.

  Hereinafter, the structure of the obtained acid-decomposable resin is shown.

  Table 1 below shows the used initiator, serial transfer agent, weight average molecular weight, degree of dispersion, and transmittance of the obtained acid-decomposable resin. The transmittance is as follows. A resin solution of propylene glycol monoacetate: propylene glycol = 6: 4 (resin content: 10% by weight) is applied onto a quartz glass substrate by spin coating, prebaked at 120 ° C., and a film pressure of 160 nm. The resist film was formed and calculated from the absorbance of the film at a wavelength of 193 nm.

The mol% in the table is mol% with respect to the total monomer mole number.
V-60: Azoisobutyronitrile V-601: Dimethyl (2,2'-2-methylpropionate)
V-40: 1,1′-azobis (cyclohexane-1-carbonitrile)

Examples 1-34 and Comparative Examples 1-4
<Resist preparation>
The components shown in Table 2 below were dissolved in a solvent to prepare a solution having a solid content concentration of 8% by mass, and this was filtered through a 0.03 m polyethylene filter to prepare a positive resist solution. The prepared positive resist solution was evaluated by the following method, and the results are also shown in Table 2.

<Resist evaluation>
An anti-reflective coating DUV-42 manufactured by Brewer Science Co., Ltd. was uniformly applied to 600 angstroms on a silicon substrate subjected to hexamethyldisilazane treatment with a spin coater, dried on a hot plate at 100 ° C. for 90 seconds, and then at 190 ° C. Heat drying was performed for 240 seconds. Thereafter, each positive resist solution was applied by a spin coater and dried at 120 ° C. for 60 seconds to form a 150 nm resist film. This resist film was exposed with an ArF excimer laser stepper (NAML = 0.75, 2/3 ring zone) through a mask, and heated on a hot plate at 120 ° C. for 60 seconds immediately after the exposure. Further, the resist film was developed with an aqueous 2.38 mass% tetramethylammonium hydroxide solution at 23 ° C. for 60 seconds, rinsed with pure water for 30 seconds, and then dried to obtain a line pattern.

<Sensitivity>
The exposure amount for reproducing the 80 nm line and space 1/1 mask pattern was determined as the optimum exposure amount (Eopt). The smaller this value, the higher the sensitivity.

<Pattern collapse>
When an exposure amount that reproduces a 130 nm line and space 1: 1 mask pattern is an optimum exposure amount, and a dense pattern of line and space 1: 1 and an isolated pattern of line and space 1:10 are exposed at the optimum exposure amount Therefore, the line width that resolves the pattern without falling down in a fine mask size is defined as the limit pattern falling line width. The smaller the value, the finer pattern is resolved without falling, and the pattern collapse is less likely to occur.
<Line edge roughness>
The line edge roughness (LER) is measured by using a length-measuring scanning electron microscope (SEM) to observe an isolated pattern of 120 nm and from the reference line where the edge in the longitudinal direction of the line pattern should be 5 μm. The distance was measured by 50 points with a length measuring SEM (Hitachi, Ltd. S-8840), the standard deviation was obtained, and 3σ was calculated. A smaller value indicates better performance.
<Pattern shape>
The shape of the obtained pattern was observed and evaluated with a scanning electron microscope (Hitachi, Ltd. S-9260).
<Development defect evaluation>
The entire surface of the 8-inch wafer was exposed with an exposure amount that a mask pattern of 130 nm line and space 1: 1 was reproduced to obtain a resist pattern. This was measured for development defects on the entire wafer surface using an intelligent line monitor 2360 manufactured by KLA Tencor.

The abbreviations in Table 2 are shown below.
[Photoacid generator]

[Basic compounds]
TPSA: triphenylsulfonium acetate DIA: 2,6-diisopropylaniline TEA: triethanolamine DBA: N, N-dibutylaniline PBI: 2-phenylbenzimidazole TMEA: tris (methoxyethoxyethyl) amine PEA: N-phenyldiethanolamine [ Surfactant]
W-1: MegaFuck F176 (Dainippon Ink Chemical Co., Ltd.) (Fluorine)
W-2: Megafuck R08 (Dainippon Ink Chemical Co., Ltd.) (fluorine and silicon)
W-3: Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) (silicon-based)
W-4: Troisol S-366 (manufactured by Troy Chemical Co., Ltd.)
〔solvent〕
S1: Propylene glycol methyl ether acetate S2: 2-heptanone S3: Cyclohexanone S4: γ-Butyrolactone S5: Propylene glycol methyl ether S6: Ethyl lactate S7: Propylene carbonate

  From the table, it is clear that the positive resist composition containing the resin of the present invention is excellent in all of LER, pattern collapse, pattern shape, and development defect.

Claims (12)

A resin (B) which contains the repeating unit (a) represented by the general formula (I) and which is produced by living radical polymerization and becomes alkali-soluble by the action of an acid.

In general formula (I),
X _a1 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R represents a group capable of decomposing and leaving by the action of an acid containing a monocyclic alicyclic group. The resin according to claim 1, wherein the repeating unit represented by the general formula (I) in the resin (B) is a repeating unit represented by the general formula (Ia).

In general formula (Ia),
X _a1 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R ₁ , R ₂ and R ₃ each independently represents an alkyl group or a monocyclic alicyclic group. However, at least one of R ₁ , R ₂ and R ₃ is a monocyclic alicyclic group. The resin according to claim 1 or 2, wherein the resin (B) further contains a repeating unit (b) represented by the general formula (I ') and having a structure different from that of the repeating unit (a).

In general formula (I ′),
X _a2 represents a hydrogen atom, an alkyl group, or a cycloalkyl group.
R ′ represents a group capable of decomposing by the action of an acid.
However, when Xa ₂ is the same as Xa ₁ in general formula (I), R ′ is not the same as R in general formula (I), and when R ′ is the same as R in general formula (I), Xa ₂ is not the same as Xa ₁ in general formula (I).   The resin according to any one of claims 1 to 3, wherein the resin (B) further contains a repeating unit (c) having a lactone structure.   The resin according to claim 1, wherein the resin (B) further contains a repeating unit having a polar group.   The resin according to any one of claims 1 to 5, wherein the resin (B) further has a repeating unit containing a non-acid-decomposable alicyclic structure. The resin according to any one of claims 1 to 6, wherein the living radical polymerization for producing the resin (B) is polymerized in the presence of a chain transfer agent represented by the general formula (II).

In general formula (II),
A represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group.
Y represents a group capable of releasing a radical containing no aryl group. The resin according to claim 7, wherein the chain transfer agent represented by the general formula (II) is represented by the general formula (II ').

In general formula (II ′),
A ₁ and A ₂ each independently represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group. The manufacturing process of the resin (B)
The method according to any one of claims 1 to 8, further comprising a step of replacing the terminal structure represented by the general formula (III) with a radical generator while adding the radical generator to the polymerization solution after polymerization. Resin.

In general formula (III),
A represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an aryl group or a heterocyclic group.   A positive resist composition comprising (A) a compound that generates an acid upon irradiation with an actinic ray or radiation, and (B) the resin according to claim 1.   The positive resist composition according to claim 10, further comprising a basic compound.   A pattern forming method comprising: forming a film with the positive resist composition according to claim 10 or 11; and exposing and developing the film.