JP2007241108A - Positive resist composition and pattern forming method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition capable of highly satisfying all of PEB temperature dependency, line edge roughness (LWR), dark/bright pattern form difference, development defects and dry etching resistance, and a pattern forming method using the positive resist composition. <P>SOLUTION: The positive resist composition comprises (A) a resin comprising a repeating unit (A1) having a lactone structure and a cyano group, and having solubility in an alkali developer increased by the action of an acid, (B) a resin comprising a repeating unit (B1) having a lactone structure and no cyano group, and having solubility in an alkali developer increased by the action of an acid, (C) a compound which generates an acid upon irradiation with an actinic ray or radiation, and (D) a solvent. The pattern forming method using the positive resist composition is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a positive resist composition whose properties change upon reaction with irradiation of actinic rays or radiation, and a pattern forming method using the positive resist composition. More specifically, a positive resist composition used in semiconductor manufacturing processes such as IC, circuit boards such as liquid crystals and thermal heads, other photofabrication processes, lithographic printing plates, acid curable compositions, and the positive resist composition. The present invention relates to a pattern forming method using a mold resist composition.

  The chemically amplified resist composition generates an acid in the exposed area by irradiation with actinic rays or radiation such as far ultraviolet light, and a reaction solution using the acid as a catalyst to develop a developing solution for the irradiated and non-irradiated areas of the active light or radiation. It is a pattern forming material that changes the solubility in the substrate and forms 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, an ArF excimer laser resist containing a resin having an alicyclic hydrocarbon structure has been developed.

  Various improvements have also been made on acid-decomposable resins that are main constituents of chemically amplified resist compositions. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-53822) discloses specific methacrylic repeating units. An acid-decomposable resin having is disclosed.

  However, it is further desired to enable high-level compatibility for PEB temperature dependency, line edge roughness (LWR), dark / bright pattern shape difference, development defect, and dry etching resistance.

JP 2004-53822 A

  Accordingly, an object of the present invention is to provide a positive resist composition that enables high-level compatibility with respect to PEB temperature dependency, line edge roughness (LWR), dark / bright pattern shape difference, development defect, and dry etching resistance. Another object of the present invention is to provide a pattern forming method using the positive resist composition.

  The present invention is as follows.

(1) (A) a resin having a lactone structure and a repeating unit (A1) having a cyano group, the solubility of which is increased in an alkaline developer by the action of an acid, (B) having a lactone structure, and A resin having a repeating unit (B1) having no cyano group and having increased solubility in an alkali developer by the action of an acid; (C) a compound capable of generating an acid upon irradiation with actinic rays or radiation; and (D) a solvent. A positive resist composition comprising:

  (2) The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) has a structure represented by the following general formula (A2) (1) The positive resist composition as described in 1. above.

In general formula (A2),
R _{1 to} R ₆ each independently represents a single bond, a hydrogen atom or a substituent. At least two of R _{1 to} R ₆ may be bonded to each other to form a ring structure. However, at least one of R _{1 to} R ₆ represents a cyano group or a substituent having a cyano group.

  (3) The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) has a structure represented by the following general formula (A6) (1) The positive resist composition as described in 1. above.

In general formula (A6),
R ₁₈ represents a single bond, a hydrogen atom or a substituent.
L ₁ represents a linking group that connects the carbon atom at the 2-position of the lactone ring and the oxygen atom of the lactone to form a lactone ring structure.
R ₁₈ and L ₁ may be bonded to each other to form a ring structure.

  (4) The lactone structure in which the repeating unit (B1) having a lactone structure and not having a cyano group in the component (B) is selected from butyrolactones, norbornane lactones, cyclohexane lactones and adamantane lactones The positive resist composition as described in any one of (1) to (3), wherein

  (5) The repeating unit (B1) having a lactone structure and having no cyano group in the component (B) has a group represented by the following general formula (B3) or (B4). The positive resist composition as described in any one of (1) to (3).

In general formulas (B3) and (B4),
X represents a methylene group, an oxygen atom or a sulfur atom.
R _{1b to} R _5b each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an alkenyl group. Two of R _{1b to} R _5b may combine to form a ring.

  (6) A pattern forming method comprising the steps of: forming a resist film from the positive resist composition according to any one of (1) to (5); and exposing and developing the resist film.

  According to the present invention, a positive resist composition capable of coexisting in a high dimension with respect to PEB temperature dependency, line edge roughness (LWR), dark / bright pattern shape difference, development defect, and dry etching resistance, and the positive resist A pattern forming method using the composition can be provided.

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

[1] (A) Resin having a lactone structure and a repeating unit (A1) having a cyano group, and having increased solubility in an alkaline developer by the action of an acid. Resin having a structure and having a repeating unit (A1) having a cyano group and having increased solubility in an alkaline developer by the action of an acid (also referred to as “(A) component” or “acid-decomposable resin (A)”) Contain).

  The lactone structure in the repeating unit (A1) is preferably a 4- to 8-membered ring lactone, more preferably a 5- to 6-membered ring lactone, from the viewpoint of polarity and stability, and a 5-membered ring. A lactone is particularly preferred.

  The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) preferably has a structure represented by the following general formula (A2).

In general formula (A2),
R _{1 to} R ₆ each independently represents a single bond, a hydrogen atom or a substituent. At least two of R _{1 to} R ₆ may be bonded to each other to form a ring structure. However, at least one of R _{1 to} R ₆ represents a cyano group or a substituent having a cyano group.

Repeating unit having a structure represented by formula (A2), the structure represented by the general formula (A2), locations which may be a hydrogen atom in R ₁ to R ₆ (i.e., as R ₁ to R ₆ It is sufficient that at least one of a hydrogen atom and a hydrogen atom in a substituent as R _{1 to} R ₆ is a bond (single bond) in either the main chain or the side chain of the repeating unit.

The substituents as R _{1 to} R ₆ are not particularly limited. For example, in addition to a cyano group, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an amino group, an amide group, and a ureido Groups, urethane groups, hydroxyl groups, carboxyl groups, halogen atoms, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, acyl groups, acyloxy groups, alkoxycarbonyl groups, nitro groups and the like. The substituent may further have a substituent. R ₁ and R ₂ , R ₃ and R ₄ , and R ₅ and R ₆ which are substituents on the same carbon atom are all the same atoms (for example, carbon atom, oxygen atom, sulfur atom, nitrogen atom). A double bond represented by C = C, C = O, C = S, C = N bond or the like may be formed. Further, any two of R _{1 to} R ₆ may be bonded to the same atom to form a three-membered ring structure or a bridged ring structure.
The substituent having a cyano group as R _{1 to} R ₆ is not particularly limited, and examples thereof include those in which the above-described substituent is substituted with a cyano group. The number of carbon atoms is 12 except for the carbon atom of the cyano group. The following is preferable, and 6 or less is more preferable.
The cyano group is particularly preferably directly connected to the lactone ring.

  The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) preferably has a structure represented by the following general formula (A3).

In the general formula (A ₃ ),
R _{7 to} R ₁₃ each independently represents a single bond, a hydrogen atom or a substituent. At least two of R _{7 to} R ₁₃ may be bonded to each other to form a ring structure.
X is, -O -, - S -, - N (R N) 2 -, or - (CH _{2) n} - represents a. ^RN represents a hydrogen atom or a substituent having 1 to 4 carbon atoms. n represents 1 or 2.
However, at least one of R _{7 to} R ₁₃ and X represents a cyano group or a group having a cyano group.

Repeating unit having a structure represented by the general formula (A3) is a structure represented by the general formula (A3), locations which may be a hydrogen atom in R ₇ to R ₁₃ (i.e., as R ₇ to R ₁₃ It is sufficient that at least one of a hydrogen atom and a hydrogen atom in a substituent as R _{7 to} R ₁₃ ) be a bond (single bond) in either the main chain or the side chain of the repeating unit.

  The structure represented by the general formula (A2) is preferably represented by the following general formula (A4).

In general formula (A4),
R ₁₄ and R ₁₅ each independently represents a single bond, a hydrogen atom or a substituent.
L ₂ represents a linking group forming a ring structure.
R ₁₄ , R ₁₅ and L ₂ may be bonded to each other to form a ring structure.
However, at least one of R ₁₄ , R ₁₅ and L ₂ represents a cyano group or a group having a cyano group.

In the repeating unit having the structure represented by the general formula (A4), the structure represented by the general formula (A4) is replaced with a site that can be a hydrogen atom in R ₁₄ , R ₁₅ and L ₂ (that is, R ₁₄ , R A hydrogen atom as ₁₅ , a hydrogen atom in a substituent as R ₁₄ and R ₁₅ , and a hydrogen atom in a linking group as L ₂ ) as a bond (single bond), What is necessary is just to have in either of the side chains.

  The structure represented by the general formula (A2) is preferably represented by the following general formula (A5).

In general formula (A5),
R ₁₆ and R ₁₇ each independently represents a single bond, a hydrogen atom or a substituent.
L ₃ represents a linking group forming a ring structure.
R ₁₆ , R ₁₇ and L ₃ may combine with each other to form a ring structure.
However, at least one of R ₁₆ , R ₁₇ and L ₃ represents a cyano group or a group having a cyano group.

In the repeating unit having the structure represented by the general formula (A5), the structure represented by the general formula (A5) is replaced with a site that can be a hydrogen atom in R ₁₆ , R ₁₇ and L ₃ (that is, R ₁₆ , R A hydrogen atom as ₁₇ , a hydrogen atom in a substituent as R ₁₆ and R ₁₇ , and a hydrogen atom in a linking group as L ₃ ) as a bond (single bond), the main chain and side chain of the repeating unit It is sufficient to have either.

  The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) preferably has a structure represented by the following general formula (A6).

In general formula (A6),
R ₁₈ represents a single bond, a hydrogen atom or a substituent.
L ₁ represents a linking group that connects the carbon atom at the 2-position of the lactone ring and the oxygen atom of the lactone to form a lactone ring structure.
R ₁₈ and L ₁ may be bonded to each other to form a ring structure.

The repeating unit having the structure represented by the general formula (A6) is obtained by replacing the structure represented by the general formula (A6) with a hydrogen atom in R ₁₈ and L ₁ (that is, a hydrogen atom as R ₁₈ , If at least one of the hydrogen atom in the substituent as R ₁₈ and the hydrogen atom in the linking group as L ₁ is a bond (single bond), either in the main chain or the side chain of the repeating unit Good.

  The structure represented by the general formula (A6) is preferably represented by the following general formula (A7).

In general formula (A7),
R _{19 to} R ₂₃ each independently represents a single bond, a hydrogen atom or a substituent. At least two of R _{19 to} R ₂₃ may be bonded to each other to form a ring structure.

Repeating unit having a structure represented by the general formula (A7) are the structures represented by the general formula (A7), locations which may be a hydrogen atom in R ₁₉ to R ₂₃ (i.e., as R ₁₉ to R ₂₃ hydrogen atom, as at least one bond of the hydrogen atoms) included in the substituents represented by hydrogen atoms and R ₁₉ to R ₂₃ in the substituent as R ₁₉ to R ₂₃ (single bond), a repeating unit backbone and side chain It is sufficient to have either.

  As the repeating unit having the structure represented by the general formulas (A2) to (A7), for example, the structure represented by the general formula (A2) to (A7) is bonded to any position in the skeleton of the following repeating unit. Can be mentioned. That is, it is obtained by substituting an arbitrary hydrogen atom in the following repeating unit with at least one of the hydrogen atom in the structure represented by the general formulas (A2) to (A7) as a bond (single bond). .

  The repeating unit (A1) is preferably a repeating unit derived from an ethylenic double bond, and more preferably a repeating unit derived from a (meth) acrylic acid derivative.

The substituents in the general formulas (A3) to (A7) are the same as those in the general formula (A2).
The substituent having a cyano group in general formulas (A3) to (A7) is the same as that in general formula (A2).
In the general formulas (A2) to (A7), examples of the ring structure formed by combining at least two substituents with each other include 5 to 6 membered rings. The ring structure may have a substituent such as a cyano group.
Examples of the ring structure formed by L ₂ and L _{3 in the} general formulas (A4) to (A5) include a norbornane structure. The ring structure may have a substituent such as a cyano group.

  As more preferred embodiments of the repeating units represented by the general formulas (A2) to (A7), there can be mentioned the repeating units represented by the following general formula (A8).

In general formula (A8),
R ^a represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may have a substituent.
Lac represents a structure represented by any one of the general formulas (A2) to (A7).

  Hereinafter, although the specific example of a repeating unit (A1) is given, this invention is not limited to this. The methyl group in the specific examples may be a hydrogen atom.

The method for synthesizing the monomer corresponding to the repeating unit (A1) is not particularly limited, but the monomer is synthesized via the alkenyl carboxylic acid (intermediate I) or its ester (intermediate II) shown in Scheme 1 and Scheme 2 below. Is preferred. Epoxidation in Scheme 1 may use a general method using mCPBA or dimethyldioxirane. When starting from Intermediate II, the same epoxycarboxylic acid can be obtained by hydrolyzing the ester moiety after epoxidation. The resulting epoxide is treated under acidic conditions to lead to hydroxylactone, and a monomer can be efficiently obtained by attaching a polymerizable group to the resulting hydroxyl group. Monomerization may use any esterification reaction.
For the lactonization in Scheme 2, a general lactonization reaction may be used. For example, a halolactonization reaction can be exemplified, and an iodolactonization reaction can be preferably exemplified. By substituting the iodine atom of the obtained iodolactone with a substituent containing a polymerizable group, it can be led to a monomer.

The acid-decomposable resin (A) is a resin whose solubility in an alkaline developer increases by the action of an acid, and decomposes into the main chain or side chain of the resin or both the main chain and side chain by the action of an acid. And a group that generates an alkali-soluble group (hereinafter also referred to as “acid-decomposable group”). Among these, a resin having a group capable of decomposing with an acid in the side chain is more preferable.
A group preferable as a group capable of decomposing with an acid is a group in which a hydrogen atom of an alkali-soluble group such as a —COOH group or —OH group is substituted with a group capable of leaving with an acid.
Examples of the group leaving with an acid include -C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), -C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), -C (R ₀₁ ) (R ₀₂ ). ) (OR ₃₉ ) and the like.
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 , R ₃₆ and R ₃₉ may be bonded to each other to form a ring.
R _{01 and} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
In the present invention, the acid-decomposable group is preferably an acetal group or a tertiary ester group.

  When the positive resist composition of the present invention is irradiated with ArF excimer laser light, the acid-decomposable resin (A) has a monocyclic or polycyclic alicyclic hydrocarbon structure and is alkali-developed by the action of an acid. It is preferable that the resin has increased solubility in the liquid.

Examples of the resin having a monocyclic or polycyclic alicyclic hydrocarbon structure and having increased solubility in an alkaline developer by the action of an acid include alicyclic carbonization represented by the following general formulas (pI) to (pV). A resin having a repeating unit having a partial structure containing hydrogen is preferable.

In general formulas (pI) to (pV),
R ₁₁ represents an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, and Z represents an atomic group necessary for forming a cycloalkyl group together with the carbon atom.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or cycloalkyl 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 a cycloalkyl 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 a cycloalkyl group. However, at least one of R _{17 to} R ₂₁ represents a cycloalkyl group. Further, either R ₁₉ or R ₂₁ represents a linear or branched alkyl group or cycloalkyl group having 1 to 4 carbon atoms.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group. However, at least one of R _{22 to} R ₂₅ represents a cycloalkyl group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

  Among (pI) to (pV), the following structures can be given as particularly preferred forms.

In the general formula (pI ′),
R _{11 ′} represents an alkyl group having 1 to 8 carbon atoms.
X _p1 represents an oxygen atom or a methylene group which may have a substituent.
R _{p1 to} R _p4 may be the same as or different from each other, and represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R _{p1 to} R _p4 may be bonded to each other to form a ring structure.
In the general formula (pI '')
R ₁₁ ″ represents an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, preferably a cycloalkyl group having 3 to 8 carbon atoms.
Z _p1 represents a single bond or —C (R _p7 ) ═C (R _p8 ) —.
R _{p5 to} R _p8 may be the same or different from each other, and each represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be bonded to each other to form a ring structure.
n represents an integer of 2 to 8.

In the general formulas (pI) to (pV), the alkyl group in R _{12 to} R ₂₅ represents a linear or branched alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. , N-butyl group, sec-butyl group, t-butyl group and the like.

The cycloalkyl group in R _{11 to} R ₂₅ or the cycloalkyl group formed by Z and the 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 cycloalkyl 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 and a cyclododecanyl group can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group.

  These alkyl groups and cycloalkyl groups may further have a substituent. As further substituents for alkyl groups and cycloalkyl groups, alkyl groups (1 to 4 carbon atoms), halogen atoms, hydroxyl groups, alkoxy groups (1 to 4 carbon atoms), carboxyl groups, alkoxycarbonyl groups (2 to 2 carbon atoms). 6). The above alkyl group, alkoxy group, alkoxycarbonyl group and the like may further have a substituent. 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.

  The structure represented by the general formulas (pI) to (pV) in the resin can form an acid-decomposable group by using it for protecting an alkali-soluble group. Examples of the alkali-soluble group include various groups known in this technical field.

  Specific examples include a structure in which a hydrogen atom of a carboxylic acid group, a sulfonic acid group, a phenol group, or a thiol group is substituted with a structure represented by the general formulas (pI) to (PV), preferably a carboxylic acid Group, the hydrogen atom of a sulfonic acid group is the structure substituted by the structure represented by general formula (pI)-(PV).

  As the repeating unit having an alkali-soluble group protected by the structure represented by the general formulas (pI) to (pV), a repeating unit represented by the following general formula (pA) is preferable.

In the general formula (pA), R represents a hydrogen atom, a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. A plurality of R may be the same or different.
A represents a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, an ester group, an amide group, a sulfonamide group, a urethane group, or a urea group, or a combination of two or more groups. Represents. A single bond is preferable.
Rp1 represents any one of the general formulas (pI) to (pV).

  The repeating unit represented by the general formula (pA) is most preferably a repeating unit of 2-alkyl-2-adamantyl (meth) acrylate and dialkyl (1-adamantyl) methyl (meth) acrylate.

  Specific examples of the repeating unit represented by the general formula (pA) are shown below.

In the above structural formulas, Rx represents H, CH ₃ , CF ₃ or CH ₂ OH, and Rxa and Rxb each independently represents an alkyl group having 1 to 4 carbon atoms.

The acid-decomposable resin (A) of the present invention preferably has a repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group. This improves the substrate adhesion and developer compatibility.
Examples of the alicyclic hydrocarbon structure substituted with a hydroxyl group include structures represented by the following general formula (VIIa) or (VIIb).

In general formula (VIIa),
R ₂ c to R ₄ c each independently represents a hydrogen atom or a hydroxyl group. However, at least one of R ₂ c to R ₄ c represents a hydroxyl group. Preferably, one or two of R ₂ c to R ₄ c are a hydroxyl group and the remaining is a hydrogen atom, more preferably _two of R ₂ c to R ₄ c are a hydroxyl group and the remaining is a hydrogen atom. It is.

  The group represented by the general formula (VIIa) is preferably a dihydroxy body or a monohydroxy body, and more preferably a dihydroxy body.

  Examples of the repeating unit having a group represented by the general formula (VIIa) or (VIIb) include a repeating unit represented by the following general formula (AIIa) or (AIIb).

In general formulas (AIIa) and (AIIb),
R ₁ c represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.
R ₂ c to R ₄ c have the same meanings as in R ₂ c to R ₄ c in formula (VIIa).

  Specific examples of the repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group are given below, but the present invention is not limited thereto.

  The acid-decomposable resin (A) of the present invention may have a repeating unit represented by the following general formula (VIII).

In general formula (VIII):
Z ₂ represents —O— or —N (R ₄₁ ) —. R ₄₁ represents a hydrogen atom, a hydroxyl group, an alkyl group, or —OSO ₂ —R ₄₂ . R ₄₂ represents an alkyl group, a cycloalkyl group or a camphor residue. The alkyl group of R ₄₁ and R ₄₂ may be substituted with a halogen atom (preferably a fluorine atom) or the like.

  Examples of the repeating unit represented by the general formula (VIII) include the following specific examples, but the present invention is not limited thereto.

  The acid-decomposable resin (A) of the present invention preferably has a repeating unit having an alkali-soluble group, and more preferably has a repeating unit having a carboxyl group. By having this, the resolution in contact hole applications increases. The repeating unit having a carboxyl group includes a repeating unit in which a carboxyl group is directly bonded to the main chain of the resin, such as a repeating unit of acrylic acid or methacrylic acid, and a carboxyl group in the main chain of the resin through a linking group. Any of the bonded repeating units is preferable, and the linking group may have a monocyclic or polycyclic hydrocarbon structure. Most preferred are acrylic acid and methacrylic acid.

  The acid-decomposable resin (A) of the present invention may have a repeating unit having 1 to 3 groups represented by the following general formula (F1). This improves line edge roughness performance.

In general formula (F1), R _{50 to} R ₅₅ each independently represents a hydrogen atom, a fluorine atom or an alkyl group. However, at least one of R _{50 to} R ₅₅ represents a fluorine atom or an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom.
Rxa represents a hydrogen atom or an organic group (preferably an acid-decomposable protecting group, an alkyl group, a cycloalkyl group, an acyl group, or an alkoxycarbonyl group).

The alkyl group of R _{50 to} R ₅₅ may be substituted with a halogen atom such as a fluorine atom, a cyano group, etc., preferably an alkyl group having 1 to 3 carbon atoms, such as a methyl group or a trifluoromethyl group. be able to.
R _{50 to} R ₅₅ are preferably all fluorine atoms.

  Examples of the organic group represented by Rxa include an acid-decomposable protecting group and an optionally substituted alkyl group, cycloalkyl group, acyl group, alkylcarbonyl group, alkoxycarbonyl group, alkoxycarbonylmethyl group, alkoxymethyl group. , 1-alkoxyethyl group is preferable.

  Preferred examples of the repeating unit having a group represented by the general formula (F1) include a repeating unit represented by the following general formula (F2).

In General Formula (F2), Rx represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Preferable substituents that the alkyl group of Rx may have include a hydroxyl group and a halogen atom.
Fa represents a single bond or a linear or branched alkylene group, preferably a single bond.
Fb represents a monocyclic or polycyclic hydrocarbon group.
Fc represents a single bond or a linear or branched alkylene group, preferably a single bond or a methylene group.
F1 represents a group represented by the general formula (F1).
P1 represents 1-3.

  The cyclic hydrocarbon group in Fb is preferably a cyclopentyl group, a cyclohexyl group, or a norbornyl group.

  Specific examples of the repeating unit having the structure of the general formula (F1) are shown below.

  In addition to the above repeating structural units, the acid-decomposable resin (A) of the present invention has dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and resolution and heat resistance, which are general necessary characteristics of resist. Various repeating structural units can be included for the purpose of adjusting properties, sensitivity and the like.

  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 (A), 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 the acid-decomposable resin (A), the molar ratio of each repeating structural unit is the resist dry etching resistance, the standard developer suitability, the substrate adhesion, the resist profile, and the general required performance of the resist, resolving power and heat resistance. It is appropriately set to adjust the property, sensitivity, etc.

  In the acid-decomposable resin (A), the content of the repeating unit having an acid-decomposable group is preferably 10 to 60 mol%, more preferably 20 to 50 mol%, still more preferably 25 to 40 in all repeating structural units. Mol%.

  In the acid-decomposable resin (A), the content of the repeating unit (A1) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, still more preferably 30 to 70 mol% in all repeating units. .

  In the acid-decomposable resin (A), the content of the repeating unit having a partial structure containing the alicyclic hydrocarbon represented by the general formulas (pI) to (pV) is 25 to 70 mol% in all repeating structural units. Is more preferable, more preferably 35 to 65 mol%, still more preferably 40 to 60 mol%.

  In addition, the content of the repeating structural unit based on the monomer of the further copolymer component in the resin can also be appropriately set according to the performance of the desired resist. ) To (pV), preferably 99 mol% or less, more preferably 90 mol% or less, still more preferably 80 mol%, based on the number of moles of the repeating structural unit having a partial structure containing an alicyclic hydrocarbon. It is as follows.

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 (A) used in the present invention is preferably one in which all of the repeating units are composed of (meth) acrylate repeating units. In this case, all of the repeating units may be methacrylate, all of the repeating units may be acrylate, or a mixture of methacrylate / acrylate, but the acrylate repeating unit is preferably 50 mol% or less of the entire repeating unit.

The acid-decomposable resin (A) used in the present invention can be synthesized according to a conventional method (for example, radical polymerization). For example, as a general synthesis method, a monomer polymerization method in which a monomer species and an initiator are dissolved in a solvent and the polymerization is performed by heating, and a solution of the monomer species and the initiator is dropped into the heating solvent over 1 to 10 hours. The dropping polymerization method is added, and the dropping polymerization method is preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane, diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, amide solvents such as dimethylformamide and dimethylacetamide, Furthermore, the solvent which melt | dissolves the composition of this invention like the below-mentioned propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone is mentioned. More preferably, the polymerization is performed using the same solvent as that used in the resist composition of the present invention. Thereby, the generation of particles during storage can be suppressed.
The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As a polymerization initiator, a commercially available radical initiator (azo initiator, peroxide, etc.) is used to initiate the polymerization. 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 examples of the initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, dimethyl 2,2′-azobis (2-methylpropionate) and the like. If desired, an initiator is added or added in portions, and 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 is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 50 to 100 ° C.

The weight average molecular weight of the acid-decomposable resin (A) is preferably 2,000 to 200,000 as a polystyrene conversion value by the GPC method. By setting the weight average molecular weight to 2,000 or more, heat resistance, dry etching resistance, and exposure latitude can be improved, and by setting the weight average molecular weight to 200,000 or less, development defects due to improved developability. The improvement effect is obtained, and the film forming property can be improved because the viscosity is lowered. The molecular weight is more preferably 5,000 to 50,000, still more preferably 7,000 to 30,000, and most preferably 8000 to 16000.
The dispersity (Mw / Mn) of the acid-decomposable resin (A) is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, and still more preferably 1.0 to 2. 0. The line edge roughness performance can be improved by adjusting the degree of dispersion to an appropriate range.

  In the positive resist composition of the present invention, the blending amount of the acid-decomposable resin (A) according to the present invention in the whole composition is preferably 40 to 99.99% by mass in the total solid content, more preferably 50 to 50%. It is 99 mass%, More preferably, it is 80-96 mass%.

[2] (B) Resin having a lactone structure and having a repeating unit (B1) not having a cyano group, and having increased solubility in an alkaline developer by the action of an acid The positive resist composition of the present invention , A resin having a repeating unit (B1) having a lactone structure and having no cyano group, and having increased solubility in an alkaline developer by the action of an acid (“(B) component” or “acid-decomposable resin ( B) ").

The repeating unit (B1) having a lactone structure and not having a cyano group may be any repeating unit having a lactone structure having no cyano group, butyrolactones and norbornane lactones. A repeating unit having a lactone structure selected from cyclohexane lactones and adamantane lactones is preferred.

  The repeating unit (B1) having a lactone structure selected from butyrolactones in the acid-decomposable resin (B) is preferably a repeating unit represented by the following general formula (II).

In general formula (II),
R ₁ represents a hydrogen atom or a methyl group.
W represents a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, or a combination of two or more groups selected from the group consisting of ester groups.
Ra, Rb, Rc, Rd and Re each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
m and n each independently represents an integer of 0 to 3, and m + n is 2 or more and 6 or less.

  Examples of the alkyl group having 1 to 4 carbon atoms of Ra to Re include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. .

In the general formula (II), examples of the alkylene group for W include groups represented by the following formulae.
-[C (Rf) (Rg)] r-
In the above formula, Rf and Rg represent a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group or an alkoxy group, and both may be the same or different. The alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group, and more preferably selected from a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the alkoxy group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the halogen atom include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom. As the substituent of the alkyl group and alkoxy group, a hydroxyl group,
A halogen atom and an alkoxy group can be mentioned. r is an integer of 1-10.

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

  In the specific example of the general formula (II), specific examples (II-17) to (II-36) are particularly preferable from the viewpoint that the exposure margin becomes better.

  As the repeating unit (B1) having a lactone structure selected from norbornanelactones and cyclohexanelactones in the acid-decomposable resin (B), the following general formulas (V-1) to (V-2) and (V -3) to repeating units having groups represented by (V-4) are preferred.

In general formulas (V-1) to (V-2),
R _{1b to} R _5b each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an alkenyl group. Two of R _{1b to} R _5b may combine to form a ring.

In general formulas (V-3) to (V-4),
R _{1b to} R _5b each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an alkenyl group. Two of R _{1b to} R _5b may combine to form a ring.

In the general formulas (V-1) to (V-4), examples of the alkyl group in R _{1b to} R _5b include linear and branched alkyl groups, which may have a substituent. The linear or branched alkyl group is preferably a linear or branched alkyl group having 1 to 12 carbon atoms, more preferably a linear or branched alkyl group having 1 to 10 carbon atoms. More preferably, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl It is a group.
As a cycloalkyl group in R _<1b > -R < _5b >, C3-C8 things, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, are preferable.
As an alkenyl group in R _<1b > -R < _5b >, C2-C6 things, such as a vinyl group, a propenyl group, a butenyl group, a hexenyl group, are preferable.
Examples of the ring formed by combining two of R _{1b to} R _5b include 3- to 8-membered rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, and a cyclooctane ring.
In the general formulas (V-1) to (V-4), R _{1b to} R _5b may be connected to any carbon atom constituting the cyclic skeleton.
Moreover, as a preferable substituent which the said alkyl group, a cycloalkyl group, and an alkenyl group may have, a C1-C4 alkoxy group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), Examples thereof include an acyl group having 2 to 5 carbon atoms, an acyloxy group having 2 to 5 carbon atoms, a cyano group, a hydroxyl group, a carboxy group, an alkoxycarbonyl group having 2 to 5 carbon atoms, and a nitro group.

  Examples of the repeating unit having a group represented by general formulas (V-1) to (V-4) include a repeating unit represented by the following general formula (AI).

In general formula (AI),
R _b0 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. As a preferable substituent which the alkyl group of R _b0 may have, as a preferable substituent which the alkyl group as R _1b in the general formulas (V-1) to (V-4) may have. What was illustrated previously is mentioned.
Examples of the halogen atom for R _b0 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
R _b0 is preferably a hydrogen atom.
A ′ represents a single bond, an ether group, an ester group, a carbonyl group, an alkylene group, or a divalent group obtained by combining these.
B ₂ represents a group represented by any one of the general formulas (V-1) to (V-4).

  In A ′, examples of the combined divalent group include those represented by the following formulae.

In the above formula, R _ab and R _bb represent a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, or an alkoxy group, and both may be the same or different.
The alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group, and more preferably selected from a methyl group, an ethyl group, a propyl group, and an isopropyl group.
Examples of the alkoxy group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.
Examples of the halogen atom include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom.
Examples of the substituent for the alkyl group and alkoxy group include a hydroxyl group, a halogen atom, and an alkoxy group having 1 to 4 carbon atoms.
r1 represents an integer of 1 to 10, preferably an integer of 1 to 4.
m represents an integer of 1 to 3, preferably 1 or 2.

  Although the specific example of the repeating unit represented by general formula (AI) is given to the following, the content of this invention is not limited to these.

The repeating unit (B1) having a lactone structure selected from adamantane lactones in the acid-decomposable resin (B) of the present invention is preferably a repeating unit represented by the following general formula (I).

In general formula (I):
A represents a single bond, an alkylene group, a cycloalkylene group, an ether group, a thioether group, a carbonyl group, or a combination of two or more groups selected from the group consisting of ester groups.
R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, or a halogen atom.

In the general formula (I), examples of the alkylene group of A include groups represented by the following formulae.
-[C (Rnf) (Rng)] r-
In the above formula, Rnf and Rng represent a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group or an alkoxy group, and both may be the same or different.
The alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group, and more preferably selected from a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the alkoxy group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the substituent for the alkyl group and alkoxy group include a hydroxyl group, a halogen atom, and an alkoxy group. Examples of the halogen atom include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom. r is an integer of 1-10.

  In the general formula (I), examples of the cycloalkylene group of A include those having 3 to 10 carbon atoms, and examples thereof include a cyclopentylene group, a cyclohexylene group, and a cyclooctylene group.

The bridged alicyclic ring containing Z may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (preferably having 1 to 4 carbon atoms), an alkoxycarbonyl group (preferably having 1 to 5 carbon atoms), an acyl group (for example, a formyl group and a benzoyl group), an acyloxy group ( For example, propyl carbonyloxy group, benzoyloxy group), an alkyl group (preferably having from 1 to 4 carbon atoms), a carboxyl group, a hydroxyl group and an alkylsulfonylsulfamoyl group (-CONHSO ₂ CH _3, etc.). In addition, the alkyl group as a substituent may be further substituted with a hydroxyl group, a halogen atom, an alkoxy group (preferably having 1 to 4 carbon atoms), or the like.
In the general formula (I), the oxygen atom of the ester group bonded to A may be bonded at any position of the carbon atom constituting the bridged alicyclic ring structure containing Z.

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

  The repeating unit (B1) having a lactone structure and not having a cyano group has a repeating unit having a group represented by the following general formula (B3) or (B4), and has good dry etching resistance and development defect performance. And particularly preferred.

In general formulas (B3) and (B4),
X represents a methylene group, an oxygen atom or a sulfur atom.
R _{1b to} R _5b each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an alkenyl group. Two of R _{1b to} R _5b may combine to form a ring.

  Hereinafter, although the specific example of the repeating unit which has group represented by general formula (B3) or (B4) is shown, this invention is not limited to this.

The acid-decomposable resin (B) is a resin whose solubility in an alkali developer increases by the action of an acid, and decomposes into the main chain or side chain of the resin or both the main chain and side chain by the action of acid. And a group that generates an alkali-soluble group (hereinafter also referred to as “acid-decomposable group”). Among these, a resin having a group capable of decomposing with an acid in the side chain is more preferable.
A group preferable as a group capable of decomposing with an acid is a group in which a hydrogen atom of an alkali-soluble group such as a —COOH group or —OH group is substituted with a group capable of leaving with an acid.
Examples of the group leaving with an acid include -C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), -C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), -C (R ₀₁ ) (R ₀₂ ). ) (OR ₃₉ ) and the like.
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 , R ₃₆ and R ₃₉ may be bonded to each other to form a ring.
R _{01 and} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
In the present invention, the acid-decomposable group is preferably an acetal group or a tertiary ester group.

  When the positive resist composition of the present invention is irradiated with ArF excimer laser light, the acid-decomposable resin (B) has a monocyclic or polycyclic alicyclic hydrocarbon structure and is alkali-developed by the action of an acid. It is preferable that the resin has increased solubility in the liquid.

  Examples of the resin having a monocyclic or polycyclic alicyclic hydrocarbon structure and having increased solubility in an alkaline developer by the action of an acid include alicyclic carbonization represented by the following general formulas (pI) to (pV). A resin having a repeating unit having a partial structure containing hydrogen is preferable.

In general formulas (pI) to (pV),
R ₁₁ represents an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, and Z represents an atomic group necessary for forming a cycloalkyl group together with the carbon atom.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or cycloalkyl 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 a cycloalkyl 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 a cycloalkyl group. However, at least one of R _{17 to} R ₂₁ represents a cycloalkyl group. Further, either R ₁₉ or R ₂₁ represents a linear or branched alkyl group or cycloalkyl group having 1 to 4 carbon atoms.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group. However, at least one of R _{22 to} R ₂₅ represents a cycloalkyl group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

  Among (pI) to (pV), the following structures can be given as particularly preferred forms.

In the general formula (pI ′),
R _{11 ′} represents an alkyl group having 1 to 8 carbon atoms.
X _p1 represents an oxygen atom or a methylene group which may have a substituent.
R _{p1 to} R _p4 may be the same as or different from each other, and represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R _{p1 to} R _p4 may be bonded to each other to form a ring structure.
In the general formula (pI '')
R ₁₁ ″ represents an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, preferably a cycloalkyl group having 3 to 8 carbon atoms.
Z _p1 represents a single bond or —C (R _p7 ) ═C (R _p8 ) —.
R _{p5 to} R _p8 may be the same or different from each other, and each represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be bonded to each other to form a ring structure.
n represents an integer of 2 to 8.

In the general formulas (pI) to (pV), the alkyl group in R _{12 to} R ₂₅ represents a linear or branched alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. , N-butyl group, sec-butyl group, t-butyl group and the like.

The cycloalkyl group represented by R _{12 to} R ₂₅ or the cycloalkyl group formed by Z and the 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 cycloalkyl 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 and a cyclododecanyl group can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group.

  These alkyl groups and cycloalkyl groups may further have a substituent. As further substituents for alkyl groups and cycloalkyl groups, alkyl groups (1 to 4 carbon atoms), halogen atoms, hydroxyl groups, alkoxy groups (1 to 4 carbon atoms), carboxyl groups, alkoxycarbonyl groups (2 to 2 carbon atoms). 6). The above alkyl group, alkoxy group, alkoxycarbonyl group and the like may further have a substituent. 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.

  The structure represented by the general formulas (pI) to (pV) in the resin can form an acid-decomposable group by using it for protecting an alkali-soluble group. Examples of the alkali-soluble group include various groups known in this technical field.

  Specific examples include a structure in which a hydrogen atom of a carboxylic acid group, a sulfonic acid group, a phenol group, or a thiol group is substituted with a structure represented by the general formulas (pI) to (PV), preferably a carboxylic acid Group, the hydrogen atom of a sulfonic acid group is the structure substituted by the structure represented by general formula (pI)-(PV).

  As the repeating unit having an alkali-soluble group protected by the structure represented by the general formulas (pI) to (pV), a repeating unit represented by the following general formula (pA) is preferable.

In the general formula (pA), R represents a hydrogen atom, a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. A plurality of R may be the same or different.
A represents a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, an ester group, an amide group, a sulfonamide group, a urethane group, or a urea group, or a combination of two or more groups. Represents. A single bond is preferable.
Rp1 represents any one of the general formulas (pI) to (pV).

  The repeating unit represented by the general formula (pA) is particularly preferably a repeating unit composed of 2-alkyl-2-adamantyl (meth) acrylate and dialkyl (1-adamantyl) methyl (meth) acrylate.

  Specific examples of the repeating unit represented by the general formula (pA) are shown below.

In the above structural formulas, Rx represents H, CH ₃ , CF ₃ or CH ₂ OH, and Rxa and Rxb each independently represents an alkyl group having 1 to 4 carbon atoms.

The acid-decomposable resin (B) of the present invention preferably has a repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group. This improves the substrate adhesion and developer compatibility.
Examples of the alicyclic hydrocarbon structure substituted with a hydroxyl group include structures represented by the following general formula (VIIa) or (VIIb).

In general formula (VIIa),
R ₂ c to R ₄ c each independently represents a hydrogen atom or a hydroxyl group. However, at least one of R ₂ c to R ₄ c represents a hydroxyl group. Preferably, one or two of R ₂ c to R ₄ c are a hydroxyl group and the remaining is a hydrogen atom, more preferably _two of R ₂ c to R ₄ c are a hydroxyl group and the remaining is a hydrogen atom. It is.

  The group represented by the general formula (VIIa) is preferably a dihydroxy body or a monohydroxy body, and more preferably a dihydroxy body.

  Examples of the repeating unit having a group represented by the general formula (VIIa) or (VIIb) include a repeating unit represented by the following general formula (AIIa) or (AIIb).

In general formulas (AIIa) and (AIIb),
R ₁ c represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.
R ₂ c to R ₄ c have the same meanings as in R ₂ c to R ₄ c in formula (VIIa).

Specific examples of the repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group are given below, but the present invention is not limited thereto.

  The acid-decomposable resin (B) of the present invention may have a repeating unit represented by the following general formula (VIII).

In general formula (VIII):
Z ₂ represents —O— or —N (R ₄₁ ) —. R ₄₁ represents a hydrogen atom, a hydroxyl group, an alkyl group, or —OSO ₂ —R ₄₂ . R ₄₂ represents an alkyl group, a cycloalkyl group or a camphor residue. The alkyl group of R ₄₁ and R ₄₂ may be substituted with a halogen atom (preferably a fluorine atom) or the like.

  Examples of the repeating unit represented by the general formula (VIII) include the following specific examples, but the present invention is not limited thereto.

The acid-decomposable resin (B) of the present invention preferably has a repeating unit having an alkali-soluble group, and more preferably has a repeating unit having a carboxyl group. By having this, the resolution in contact hole applications increases. The repeating unit having a carboxyl group includes a repeating unit in which a carboxyl group is directly bonded to the main chain of the resin, such as a repeating unit of acrylic acid or methacrylic acid, and a carboxyl group in the main chain of the resin through a linking group. Any of the bonded repeating units is preferable, and the linking group may have a monocyclic or polycyclic hydrocarbon structure. Most preferred are acrylic acid and methacrylic acid.

  The acid-decomposable resin (B) of the present invention may have a repeating unit having 1 to 3 groups represented by the following general formula (F1). This improves line edge roughness performance.

In general formula (F1), R _{50 to} R ₅₅ each independently represents a hydrogen atom, a fluorine atom or an alkyl group. However, at least one of R _{50 to} R ₅₅ represents a fluorine atom or an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom.
Rxa represents a hydrogen atom or an organic group (preferably an acid-decomposable protecting group, an alkyl group, a cycloalkyl group, an acyl group, or an alkoxycarbonyl group).

The alkyl group of R _{50 to} R ₅₅ may be substituted with a halogen atom such as a fluorine atom, a cyano group, etc., preferably an alkyl group having 1 to 3 carbon atoms, such as a methyl group or a trifluoromethyl group. be able to.
R _{50 to} R ₅₅ are preferably all fluorine atoms.

  Examples of the organic group represented by Rxa include an acid-decomposable protecting group and an optionally substituted alkyl group, cycloalkyl group, acyl group, alkylcarbonyl group, alkoxycarbonyl group, alkoxycarbonylmethyl group, alkoxymethyl group. , 1-alkoxyethyl group is preferable.

  Preferred examples of the repeating unit having a group represented by the general formula (F1) include a repeating unit represented by the following general formula (F2).

In General Formula (F2), Rx represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Preferable substituents that the alkyl group of Rx may have include a hydroxyl group and a halogen atom.
Fa represents a single bond or a linear or branched alkylene group, preferably a single bond.
Fb represents a monocyclic or polycyclic hydrocarbon group.
Fc represents a single bond or a linear or branched alkylene group, preferably a single bond or a methylene group.
F1 represents a group represented by the general formula (F1).
P1 represents 1-3.

  The cyclic hydrocarbon group in Fb is preferably a cyclopentyl group, a cyclohexyl group, or a norbornyl group.

  Specific examples of the repeating unit having the structure of the general formula (F1) are shown below.

  In addition to the above repeating structural units, the acid-decomposable resin (B) of the present invention has dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and general required properties of resist, resolving power and heat resistance. Various repeating structural units can be included for the purpose of adjusting properties, sensitivity, and the like.

  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 (B), 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 the acid-decomposable resin (B), the molar ratio of each repeating structural unit is the resist dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and the general required performance of the resist, resolving power and heat resistance. It is appropriately set to adjust the property, sensitivity, etc.

  In the acid-decomposable resin (B), the content of the repeating unit having an acid-decomposable group is preferably 10 to 60 mol%, more preferably 20 to 50 mol%, still more preferably 25 to 40 in all repeating structural units. Mol%.

  In the acid-decomposable resin (B), the content of the repeating unit (B1) is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, still more preferably 30 to 70 mol% in all repeating units. .

  In the acid-decomposable resin (B), the content of the repeating unit having a partial structure containing the alicyclic hydrocarbon represented by the general formulas (pI) to (pV) is 25 to 70 mol% in all repeating structural units. Is more preferable, more preferably 35 to 65 mol%, still more preferably 40 to 60 mol%.

  In addition, the content of the repeating structural unit based on the monomer of the further copolymer component in the resin can also be appropriately set according to the performance of the desired resist. ) To (pV), preferably 99 mol% or less, more preferably 90 mol% or less, still more preferably 80 mol%, based on the number of moles of the repeating structural unit having a partial structure containing an alicyclic hydrocarbon. It is as follows.

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 (B) used in the present invention is preferably one in which all of the repeating units are composed of (meth) acrylate repeating units. In this case, all of the repeating units may be methacrylate, all of the repeating units may be acrylate, or a mixture of methacrylate / acrylate, but the acrylate repeating unit is preferably 50 mol% or less of the entire repeating unit.

The acid-decomposable resin (B) used in the present invention can be synthesized according to a conventional method (for example, radical polymerization). For example, as a general synthesis method, a monomer polymerization method in which a monomer species and an initiator are dissolved in a solvent and the polymerization is performed by heating, and a solution of the monomer species and the initiator is dropped into the heating solvent over 1 to 10 hours. The dropping polymerization method is added, and the dropping polymerization method is preferable. Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane, diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, amide solvents such as dimethylformamide and dimethylacetamide, Furthermore, the solvent which melt | dissolves the composition of this invention like the below-mentioned propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone is mentioned. More preferably, the polymerization is performed using the same solvent as that used in the resist composition of the present invention. Thereby, the generation of particles during storage can be suppressed.
The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As a polymerization initiator, a commercially available radical initiator (azo initiator, peroxide, etc.) is used to initiate the polymerization. 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 examples of the initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, dimethyl 2,2′-azobis (2-methylpropionate) and the like. If desired, an initiator is added or added in portions, and 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 is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 50 to 100 ° C.

The weight average molecular weight of the acid-decomposable resin (B) is preferably 2,000 to 200,000 as a polystyrene conversion value by the GPC method. By setting the weight average molecular weight to 2,000 or more, heat resistance, dry etching resistance, and exposure latitude can be improved, and by setting the weight average molecular weight to 200,000 or less, development defects due to improved developability. The improvement effect is obtained, and the film forming property can be improved because the viscosity is lowered. The molecular weight is more preferably 5,000 to 50,000, still more preferably 7,000 to 30,000, and most preferably 8000 to 16000.
The dispersity (Mw / Mn) of the acid-decomposable resin (B) is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, and still more preferably 1.0 to 2. 0. The line edge roughness performance can be improved by adjusting the degree of dispersion to an appropriate range.

  In the positive resist composition of the present invention, the blending amount of the acid-decomposable resin (B) according to the present invention in the entire composition is preferably 40 to 99.99% by mass, more preferably 50 to 50% in the total solid content. It is 99 mass%, More preferably, it is 80-96 mass%.

<Blend ratio>
The acid-decomposable resin (A) and the acid-decomposable resin (B) may be used alone or as a plurality of resins, but at least one acid-decomposable resin (B) is always used. At least one kind is used. The blend ratio of the acid-decomposable resin (A) and the acid-decomposable resin (B) is preferably 1:99 to 99: 1 by mass ratio, more preferably in the range of 5:95 to 95: 5, still more preferably. The range is from 10:90 to 90:10. When the ratio of the acid-decomposable resin (A) is too small, the PEB temperature dependency is deteriorated, and when the ratio of the acid-decomposable resin (B) is too large, the dependence of the pattern shape on the dark mask and bright mask increases.

[3] (C) Compound capable of generating acid upon irradiation with actinic ray or radiation Compound used for positive resist composition of the present invention to generate acid upon irradiation with actinic ray or radiation (hereinafter referred to as “acid generator”) Will be described below.
The acid generator used in the present invention can be selected from compounds generally used as an acid generator.
In other words, photoinitiators for photocationic polymerization, photoinitiators for radical photopolymerization, photodecolorants for dyes, photochromic agents, or active rays or radiations such as far ultraviolet rays and X-rays used in micro resists, etc. A known compound that generates an acid by irradiation and a mixture 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.

  Preferred compounds among the acid generators include compounds represented by the following general formulas (ZI), (ZII), and (ZIII).

In the general formula (ZI),
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
X ⁻ represents a non-nucleophilic anion.

The carbon number of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ is generally 1-30, preferably 1-20.
Two of R _{201 to} R ₂₀₃ may be bonded 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 (ZI) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (ZI) is, at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (ZI) It may be a compound.

As more preferred (ZI) components, compounds (ZI-1) and (ZI-2) described below
And (ZI-3).

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 a phenyl group or a naphthyl group, and more preferably a phenyl group. The aryl group may be an aryl group having a heterocyclic structure having an oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of the aryl group having a heterocyclic structure include a pyrrole residue (a group formed by losing one hydrogen atom from pyrrole) and a furan residue (a group formed by losing one hydrogen atom from furan). Groups), thiophene residues (groups formed by the loss of one hydrogen atom from thiophene), indole residues (groups formed by the loss of one hydrogen atom from indole), benzofuran residues ( A group formed by losing one hydrogen atom from benzofuran), a benzothiophene residue (a group formed by losing one hydrogen atom from benzothiophene), and the like. 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 (e.g., having from 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, a phenylthio group, or the like, as a substituent. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and alkoxy groups having 1 to 12 carbon atoms, most preferably alkyl having 1 to 4 carbon atoms. Group, an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Examples of the non-nucleophilic anion as X ⁻ include a sulfonate anion, a carboxylate anion, a sulfonylimide anion, a bis (alkylsulfonyl) imide anion, and a tris (alkylsulfonyl) methyl anion.

A non-nucleophilic anion is an anion that has an extremely low ability to cause a nucleophilic reaction, and is an anion that can suppress degradation over time due to an intramolecular nucleophilic reaction. This improves the temporal stability of the resist.

  Examples of the sulfonate anion include an aliphatic sulfonate anion, an aromatic sulfonate anion, and a camphor sulfonate anion.

  Examples of the carboxylate anion include an aliphatic carboxylate anion, an aromatic carboxylate anion, and an aralkylcarboxylate anion.

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

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

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

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

  Examples of the aliphatic group in the aliphatic carboxylate anion include those similar to the aliphatic group in the aliphatic sulfonate anion.

  Examples of the aromatic group in the aromatic carboxylate anion include the same aromatic groups as in the aromatic sulfonate anion.

  The aralkyl group in the aralkyl carboxylate anion is preferably an aralkyl group having 6 to 12 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylmethyl group.

  The aliphatic group, aromatic group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion may have a substituent. Examples of the substituent include aliphatic sulfonic acid The same halogen atom, alkyl group, cycloalkyl group, alkoxy group, alkylthio group and the like as in the anion can be exemplified.

  Examples of the sulfonylimide anion include saccharin anion.

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

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

Examples of the non-nucleophilic anion of X ⁻ include an aliphatic sulfonate anion in which the α-position of the sulfonic acid is substituted with a fluorine atom, an aromatic sulfonate anion substituted with a fluorine atom or a group having a fluorine atom, and an alkyl group. A bis (alkylsulfonyl) imide anion substituted with a fluorine atom and a tris (alkylsulfonyl) methide anion wherein an alkyl group is substituted with a fluorine atom are preferred. The non-nucleophilic anion is particularly preferably a perfluoroaliphatic sulfonic acid anion having 4 to 8 carbon atoms, an aromatic sulfonic acid anion having a fluorine atom, most preferably a nonafluorobutanesulfonic acid anion, a perfluorooctanesulfonic acid anion, It is a pentafluorobenzenesulfonic acid anion and 3,5-bis (trifluoromethyl) benzenesulfonic acid anion.

Next, the compound (ZI-2) will be described.
Compound (ZI-2) is a compound in the case where R _{201 to} R ₂₀₃ in formula (ZI) each independently represents an organic group not containing an aromatic ring. Here, the aromatic ring includes an aromatic ring containing a hetero atom.

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

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

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

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

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

The alkoxy group in the alkoxycarbonylmethyl group is preferably an alkoxy group having 1 to 5 carbon atoms (methoxy group, ethoxy group, propoxy group, butoxy group, 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 _{1c to} R _5c each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group or a halogen atom.
R _6c and R _7c each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
R _x and R _y each independently represents an alkyl group, a cycloalkyl group, an allyl group or a vinyl group.
Any two or more of R _1c to R _7c, and R _x and R _y may be bonded to each other to form a ring structure, the ring structure may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond May be included. Examples of the group formed by combining any two or more of R _{1c to} R _7c and R _x and R _y are a butylene group and a pentylene group.
Zc ⁻ represents a non-nucleophilic anion, and examples thereof include the same as the non-nucleophilic anion of X ^{− in} formula (ZI).

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

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

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

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

_Examples of the alkyl group and cycloalkyl group as R _x and R _y include the same alkyl groups and cycloalkyl groups as R _{1c to} R _{7c, such} as a 2-oxoalkyl group and a 2-oxocycloalkyl group. An alkoxycarbonylmethyl group is more preferable.

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

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

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

In general formulas (ZII) and (ZIII),
R ₂₀₄ to R ₂₀₇ each independently represents an aryl group, an alkyl group or a cycloalkyl group.

Phenyl group and a naphthyl group are preferred as the aryl group of R ₂₀₄ to R _207, more preferably a phenyl group. Aryl group R ₂₀₄ to R ₂₀₇ represents an oxygen atom, a nitrogen atom, may be an aryl group having a heterocyclic structure having a sulfur atom and the like. Examples of the aryl group having a heterocyclic structure include a pyrrole residue (a group formed by losing one hydrogen atom from pyrrole) and a furan residue (a group formed by losing one hydrogen atom from furan). Groups), thiophene residues (groups formed by the loss of one hydrogen atom from thiophene), indole residues (groups formed by the loss of one hydrogen atom from indole), benzofuran residues ( A group formed by losing one hydrogen atom from benzofuran), a benzothiophene residue (a group formed by losing one hydrogen atom from benzothiophene), and the like.

The alkyl group as R ₂₀₄ to R ₂₀₇ is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group.

The cycloalkyl group as R ₂₀₄ to R ₂₀₇ is preferably a cycloalkyl group having 3 to 10 carbon atoms, e.g., cyclopentyl, cyclohexyl group and a norbornyl group.

The R ₂₀₄ to R ₂₀₇ are substituents which may have, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (e.g., 6 carbon atoms 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.

X ⁻ represents a non-nucleophilic anion, and examples thereof include the same non-nucleophilic anion as X ^{− in} formula (ZI).

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

In general formula (ZIV), two Ar ₃ each independently represents an aryl group.
R ₂₀₈ in the general formulas (ZV) and (ZVI) each independently represents an alkyl group, a cycloalkyl group or an aryl group, and the alkyl groups as R _{204 to} R ₂₀₇ in the general formulas (ZI) to (ZIII) , Cycloalkyl group or aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

  Among the acid generators, compounds represented by the general formulas (ZI) to (ZIII) are more preferable.

  As the acid generator in the present invention, particularly preferably, an anion structure containing an alkyl group having 4 or less carbon atoms substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, or an aromatic group substituted with a fluorine atom; An acid generator having a triarylsulfonium cation structure. Such acid generators are preferably those represented by the following general formulas (B1) to (B3).

In general formulas (B1) to (B3),
R ₁ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, an alkoxy group or a halogen atom.
y represents 0 or an integer of 1 to 5 independently of each other. When y is an integer of 2 or more, two or more R _{1 s} may be the same or different.
Q _{1 to} Q ₄ are each independently an alkyl group having 1 to 8 carbon atoms substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom, or a fluorinated alkyl group. Represents a substituted aryl group.
In particular, in the general formula (B2), Q ₂ and Q _{3 which} are bonded to form a ring structure are preferable from the viewpoint of improving exposure latitude.

As the alkyl group for R ₁ , a linear or branched alkyl group having 1 to 15 carbon atoms is preferable, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, and a t-butyl group. Can be mentioned.
The alicyclic hydrocarbon group for R ₁ is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.
The alkyl group substituted with a fluorine atom Q ₁ to Q _4, for _{example, -CF 3, -C 2 F 5} , -n-C 3 F 7, -n-C 4 F 9, -n-C 8 _{F 17, -CF (CF 3)} 2, -CH (CF 3) 2, - (CF 2) 2 OCF 2 CF 3, - (CF 2) 2 O (CH 2) 3 CH 3, - (CF 2) _{2 O (CH 2) 13 CH} 3, - (CF 2) 2 O (CF 2) 2 (CH 2) 3 CH 3 and the like. The alkyl group having 4 or less carbon atoms substituted with a fluorine atom of Q _{1 to} Q ₄ may further have a substituent such as an alkoxy group or a fluoroalkoxy group.
Examples of the aryl group substituted with a fluorine atom of Q _{1 to} Q ₄ include 2,3,4,5,6-pentafluorophenyl group, 2,3,4-trifluorophenyl group, and 2,4-difluoro. A phenyl group, 4-fluorophenyl group, 4-undecanyloxy-2,3,5,6-tetrafluorophenyl group and the like can be mentioned.
Examples of the aryl group substituted with a fluorinated alkyl group of Q _{1 to} Q ₄ include a 3-trifluoromethylphenyl group, a 3,5-bis (trifluoromethyl) phenyl group, a 4-trifluoromethylphenyl group, And 4-n-nonafluorobutylphenyl group.

  Examples of particularly preferable acid generators are given below.

An acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the acid generator in the positive resist composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, still more preferably, based on the total solid content of the positive resist composition. Is 1-7 mass%.

[4] (D) Solvent The positive resist composition of the present invention is used by dissolving each component in a predetermined solvent.
Solvents that can be used include, for example, 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- Examples thereof include dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and tetrahydrofuran.

  In the present invention, the solvent may be used alone or mixed, but it is preferable to use a mixed solvent containing two or more kinds of solvents having different functional groups. As the mixed solvent having different functional groups, a mixed solvent in which a solvent having a hydroxyl group in the structure and a solvent having no hydroxyl group are mixed, or a mixed solvent in which a solvent having an ester structure and a solvent having a ketone structure are mixed. Is preferably used. Thereby, the generation of particles during storage of the resist solution can be reduced.

  Examples of the solvent having 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. Propylene glycol monomethyl ether and ethyl lactate are more preferable.

  Examples of the solvent having no hydroxyl group include propylene glycol monomethyl ether acetate, ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone, butyl acetate, N-methylpyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide. Of 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 ethoxypropio Nate, 2-heptanone and cyclohexanone are particularly preferred.

  The mixing ratio (mass) of the solvent having a hydroxyl group and the solvent having no hydroxyl group is usually 1/99 to 99/1, preferably 10/90 to 90/10, and more preferably 20/80 to 60/40. is there. A mixed solvent containing 50% by mass or more of a solvent having no hydroxyl group is preferable in terms of coating uniformity.

In a mixed solvent in which a solvent having an ester structure and a solvent having a ketone structure are mixed, 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, γ-butyrolactone, and butyl acetate, with propylene glycol monomethyl ether acetate being preferred.
The mixing ratio (mass) of the solvent having an ester structure and the solvent having a ketone structure is usually 1/99 to 99/1, preferably 10/90 to 90/10, more preferably 20/80 to 60/40. is there. 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.

[5] (E) Basic compound The positive resist composition of the present invention preferably contains a basic compound in order to reduce the change in performance over time from exposure to heating.

  Preferred examples of the basic compound include compounds having structures represented by the following formulas (A) to (E).

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

In the formula, R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R ²⁵⁶ each independently represent an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 3 to 20 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.

  In the positive resist composition of the present invention, the basic compound is used alone or in combination of two or more. The amount of the basic compound used is generally 0.001 to 10% by mass, preferably 0.01 to 5% by mass, based on the solid content of the positive resist composition. 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.

[6] (F) A dissolution inhibiting compound having a molecular weight of 3000 or less (hereinafter also referred to as “component (E)” or “dissolution inhibiting compound”) that decomposes by the action of an acid to increase the solubility in an alkaline developer.
As a dissolution inhibiting compound having a molecular weight of 3000 or less, which is decomposed by the action of an acid to increase the solubility in an alkaline developer, the permeability of 220 nm or less is not lowered.
An alicyclic or aliphatic compound containing an acid-decomposable group is preferred, such as a cholic acid derivative containing an acid-decomposable group described in SPIE, 2724,355 (1996). Examples of the acid-decomposable group and alicyclic structure are the same as those described above for the alicyclic hydrocarbon-based acid-decomposable resin.

  When the positive resist composition of the present invention is exposed with a KrF excimer laser or irradiated with an electron beam, it preferably contains a structure in which the phenolic hydroxyl group of the phenol compound is substituted with an acid-decomposable group. As a phenol compound, what contains 1-9 phenol frame | skeleton is preferable, More preferably, it contains 2-6 pieces.

  The molecular weight of the dissolution inhibiting 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 inhibiting compound is preferably 3 to 50% by mass, more preferably 5 to 40% by mass, based on the solid content of the positive resist composition.

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

[7] (G) Surfactant The positive resist composition of the present invention preferably contains a surfactant, and is a fluorine-based and / or silicon-based surfactant (fluorine-based surfactant and silicon-based surfactant). It is more preferable to contain one or more of an agent, a surfactant containing both a fluorine atom and a silicon atom).

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, 4430 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176, F189 , F113, F110, F177, F120, R08 (manufactured by Dainippon Ink & Chemicals, Inc.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (manufactured by Asahi Glass Co., Ltd.), Troisol S-366 (Manufactured by Troy Chemical Co., Ltd.), GF-300, GF-150 (manufactured by Toa Gosei Chemical Co., Ltd.), Surflon S-393 (manufactured by Seimi Chemical Co., Ltd.), F-top EF121, EF122A, EF122B, RF122C, EF125M , EF135M, EF351, 352, EF801, EF802, EF 01 (manufactured by Gemco), PF636, PF656, PF6320, PF6520 (manufactured by OMNOVA), FTX-204D, 208G, 218G, 230G, 204D, 208D, 212D, 218, 222D (manufactured by Neos) Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

  In addition to the known surfactants described above, the surfactant is derived from a fluoroaliphatic compound produced by a telomerization method (also called telomer method) or an oligomerization method (also called oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.

  As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. 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.

  In the present invention, other surfactants other than fluorine-based and / or silicon-based surfactants can also be used. Specifically, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol ether, etc. Sorbitans such as polyoxyethylene alkyl allyl ethers, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Fatty acid esters, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopal Te - DOO, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, may be mentioned polyoxyethylene sorbitan tristearate nonionic surfactants of polyoxyethylene sorbitan fatty acid esters such as such.

  Surfactants may be used alone or in several combinations.

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

<Other additives>
If necessary, the positive resist composition of the present invention may further contain a dye, a light absorber, a plasticizer, a photosensitizer, a compound that promotes solubility in a developer, and the like.

  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.

  The 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 component (A) and the component (B). 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.

  As the plasticizer, in addition to a commercially available plasticizer, any compound having a molecular weight of 1000 or less that is compatible with the polymer to be used and has an effect of lowering the softening point of the film may be used without particular limitation. From the viewpoint of compatibility, a molecular weight of 750 or less is preferable, and a molecular weight of 500 or less is more preferable. A compound having a normal pressure boiling point of 300 ° C. or higher and a melting point of 20 ° C. or lower is preferable. Specific examples include diisobutyl phthalate, tricresyl phosphate, triethylene glycol diphenyl ether, diethylene glycol dibenzoate, and triethylene glycol diacetate.

  As the light absorber, any compound that has absorption at the exposure wavelength and does not generate an acid upon exposure can be used without particular limitation. When the light source wavelength is 193 nm, a compound containing an aromatic ring is preferred. Specific examples include benzene derivatives, naphthalene derivatives, anthracene derivatives, furan derivatives, thiophene derivatives, indole derivatives, and the like.

(Pattern formation method)
The positive resist composition of the present invention is used by dissolving the above components in a predetermined solvent, preferably the mixed solvent, and applying the solution on a predetermined support as follows.

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) and developed. Thereby, a good pattern can be obtained.
Exposure (immersion exposure) may be performed by filling a liquid 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.

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.

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, and AR-2, AR-3, AR-5 manufactured by Shipley may be used. it can.

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

Synthesis Example 1 (Synthesis of Resin (A-1))
A methacrylate having cyanooxanorbornane lactone, hydroxyadamantyl acrylate, 2- (4-methylcyclohexyl) isopropyl methacrylate, and carboxyadamantyl methacrylate are charged at a ratio (molar ratio) of 30/20/40/10, dissolved in methyl ethyl ketone, 450 g of a 22% concentration solution was prepared. 10 mol% of Wako Pure Chemical Co., Ltd. polymerization initiator V-601 was added to this solution, and this was added dropwise to 50 g of methyl ethyl ketone heated to 80 ° C. over 6 hours in a nitrogen atmosphere. The reaction liquid was stirred for 4 hours after completion | finish of dripping. After completion of the reaction, the reaction solution was cooled to room temperature, crystallized in 5 L of a mixed solvent of ethyl acetate / hexane = 3/7 (mass ratio), and the precipitated white powder was filtered out. Reslurry with 1 L, and the target resin (A-1) was recovered. The polymer composition ratio (molar ratio) determined from NMR was 30/20/39/11. Moreover, the weight average molecular weight of standard polystyrene conversion measured by GPC was 7800, and dispersion degree Mw / Mn = 1.8.

Resins (A-2) to (A-10) and resins (B-1) to (B-14) were synthesized in the same manner as in Synthesis Example 1.
The structures of synthesized resins (A-1) to (A-10) and resins (B-1) to (B-14) are shown below.

  In Table 1 below, composition ratios (molar ratio, corresponding to each repeating unit in order from the left) of resins (A-1) to (A-10) and resins (B-1) to (B-14), weight average molecular weight And the degree of dispersion.

Examples 1-14 and Comparative Examples 1-10
<Resist preparation>
The components shown in Table 2 below were dissolved in a solvent to prepare a solution having a solid content concentration of 10% by mass, and this was filtered through a 0.1 μm polyethylene filter to prepare a positive resist solution. The prepared positive resist solution was evaluated by the following method, and the results are shown in Table 3.

  The acid generators in Table 2 are as follows.

The basic compounds in Table 2 are as follows.
N-1: N, N-dibutylaniline N-2: Trioctylamine N-3: N, N-dihydroxyethylaniline N-4: 2,4,5-triphenylimidazole N-5: 2,6-diisopropyl Aniline N-6: Hydroxyantipyrine N-7: Trismethoxymethoxyethylamine N-8: Triethanolamine

  The additives in Table 2 are as follows.

The surfactants in Table 2 are as follows.
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.)
W-5: KH-20 (Asahi Kasei Corporation)

The solvents in Table 2 are as follows.
Group a SL-1: Propylene glycol monomethyl ether acetate SL-2: Propylene glycol monomethyl ether propionate SL-3: 2-heptanone Group b SL-4: Ethyl lactate SL-5: Propylene glycol monomethyl ether SL-6: Cyclohexanone Group c SL-7: γ-butyrolactone SL-8: Propylene carbonate

<Standard resist evaluation>
An antireflection film ARC29A manufactured by Brewer Science Co., Ltd. was uniformly applied to a silicon substrate with a spin coater at 780 Å, dried on a hot plate at 205 ° C. for 60 seconds, and then cooled to room temperature. Thereafter, each positive resist solution was applied by a spin coater and dried at 120 ° C. for 60 seconds to form a 160 nm resist film.
The resist film was exposed with an ArF excimer laser stepper (SM = NA = 0.75) through a 90 nm 1: 1 line and space mask while changing the exposure amount. Immediately after the exposure, a hot plate was formed at 120 ° C. for 60 seconds. After heating above, it was cooled to room temperature. 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.
<PEB temperature dependency evaluation>
In the standard resist evaluation, three types of wafers were prepared: one obtained by performing a post-exposure heating step (PEB) at 117 ° C., one conducted at 120 ° C., and one conducted at 123 ° C. in each resist. About 120 degreeC PEB, the exposure amount with a line pattern finished at 90 nm was determined by observing with an electron microscope (S9260 manufactured by Hitachi, Ltd.), and PEB was performed at 117 ° C. and 123 ° C. with the exposure amount. The line pattern dimensions were determined for the samples. By subtracting the size of the PEB at 123 ° C. from the size of the PEB at 117 ° C. and dividing the difference by the PEB temperature difference of 6 ° C., the dimensional change rate per 1 ° C. was expressed as PEB temperature dependence. .
<Dark mask and bright mask dependency evaluation>
In the standard resist evaluation, wafers were prepared using the dark mask (a) and the bright mask (b) shown in FIG. 1 as masks for transferring a 90 nm 1: 1 line and space line pattern, respectively. In each case, the cross-sectional shape of the pattern at the exposure amount at which the line pattern was finished at 90 nm was observed with an electron microscope (S4800, manufactured by Hitachi, Ltd.), and when the dark mask of (a) was used and the bright mask of (b) When the shape difference was used, the case where the shape difference was large was indicated as x, the case where it was slightly different as Δ, and the case where there was no change as ○.
<LWR evaluation>
In the standard resist evaluation, the line pattern finished to 90 nm is observed with a scanning microscope (S9260 manufactured by Hitachi, Ltd.), and the distance from the reference line where the edge should be in the range of 2 μm edge in the longitudinal direction of the line pattern is set to 50. Point measurement was performed to obtain a standard deviation, and 3σ was calculated. A smaller value indicates better performance.
<Defect evaluation>
In the standard resist evaluation, a repetitive pattern was formed on the entire surface of the wafer with an exposure amount at which the line pattern was finished at 90 nm, and the number of development defects was measured with a KLA 2112 machine (manufactured by KLA Tencor) (Threshold = 12, Pixel size = 0 .39). The evaluation results are shown by the number of defects for each wafer.
<Dry etching resistance>
After applying a resist with a film thickness of 300 nm on a Si wafer, Ar / C ₄ F ₆ / O ₂ = 100: 4: 2 gas for 2 minutes using a dry etcher (U-621) manufactured by Hitachi High-Technology Corporation. Plasma dry etching was performed, the amount of remaining film was measured, and the etching rate per second was calculated. The smaller the etching rate value, the better the performance.

From Table 3, the positive resist composition of the present invention has PEB temperature dependency, line edge roughness (LWR), dark / bright pattern shape difference, development defect, dry etching resistance,
It is clear that it has been improved.

It is drawing which shows a dark mask and a bright mask in dark mask and bright mask dependence evaluation.

Explanation of symbols

a Dark mask b Bright mask

Claims (6)

  (A) a resin having a lactone structure and a repeating unit (A1) having a cyano group, the solubility of which is increased in an alkaline developer by the action of an acid, (B) a lactone structure and having a cyano group It contains a repeating unit (B1) that does not have, and a resin whose solubility in an alkaline developer is increased by the action of an acid, (C) a compound that generates an acid upon irradiation with actinic rays or radiation, and (D) a solvent. A positive resist composition characterized by the above. The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) has a structure represented by the following general formula (A2). Positive resist composition.

In general formula (A2),
R _{1 to} R ₆ each independently represents a single bond, a hydrogen atom or a substituent. At least two of R _{1 to} R ₆ may be bonded to each other to form a ring structure. However, at least one of R _{1 to} R ₆ represents a cyano group or a substituent having a cyano group. The repeating unit (A1) having a lactone structure and having a cyano group in the component (A) has a structure represented by the following general formula (A6). Positive resist composition.

In general formula (A6),
R ₁₈ represents a single bond, a hydrogen atom or a substituent.
L ₁ represents a linking group that connects the carbon atom at the 2-position of the lactone ring and the oxygen atom of the lactone to form a lactone ring structure.
R ₁₈ and L ₁ may be bonded to each other to form a ring structure.   The repeating unit (B1) having a lactone structure and not having a cyano group in component (B) has a lactone structure selected from butyrolactones, norbornane lactones, cyclohexane lactones and adamantane lactones. The positive resist composition according to any one of claims 1 to 3. The repeating unit (B1) having a lactone structure and not having a cyano group in the component (B) has a group represented by the following general formula (B3) or (B4) The positive resist composition according to claim 1.

In general formulas (B3) and (B4),
X represents a methylene group, an oxygen atom or a sulfur atom.
R _{1b to} R _5b each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an alkenyl group. Two of R _{1b to} R _5b may combine to form a ring.   A pattern forming method comprising: forming a resist film from the positive resist composition according to claim 1; and exposing and developing the resist film.

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