JP4621807B2 - Positive resist composition and pattern forming method using the same - Google Patents

Description

  The present invention relates to a positive resist composition used in semiconductor manufacturing processes such as ICs, circuit boards such as liquid crystals and thermal heads, and other photofabrication processes, and a pattern forming method using the same. .

  The resist composition generates an acid in the exposed area by irradiation with actinic light or radiation, and by the reaction using this acid as a catalyst, the solubility of the active light or radiation irradiated part and the non-irradiated part in the developer is changed, A pattern forming material for forming a pattern on a substrate.

  Regarding acid generators that generate an acid upon irradiation with actinic rays or radiation, for example, Patent Document 1, Patent Document 2 and the like describe triarylsulfonium salts having a fluorine atom.

  However, the conventional resist composition has been desired to be further improved in terms of resolution, sensitivity, initial particle value, profile, and curvature reproducibility. Curvature reproducibility is an important characteristic for forming a desired pattern shape. In particular, it is possible to reproduce the pattern shape of a bent part when a bent line pattern is drawn. From the viewpoint of post-processing (ultra-fine processing of a substrate) Is important.

International Publication No. 02/092559 JP 2000-258902 A

  An object of the present invention is to provide a positive resist composition improved in resolving power, sensitivity, initial particle value, profile, and curvature reproducibility, and a pattern forming method using the same.

  The present invention has the following configuration, whereby the above object of the present invention is achieved.

(1) (A) a resin whose solubility in an alkaline developer is increased by the action of an acid;
(B-1) a triarylsulfonium salt having a fluorine atom in the cation moiety, which generates an aliphatic or aromatic sulfonic acid having a fluorine atom by irradiation with an actinic ray or radiation,
(B-2) a sulfonium salt that does not have a fluorine atom in the cation moiety, generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation, (C) a nitrogen-containing basic compound, and (D) A positive resist composition comprising an organic solvent.

(2) As the organic solvent of the component (D), at least one selected from the following group A solvents, at least one selected from the group B solvents and / or at least one selected from the group C solvents. The positive resist composition as described in (1), which is contained.
Group A solvent: propylene glycol monoalkyl ether carboxylate Group B solvent: propylene glycol monoalkyl ether, alkyl lactate and alkyl alkoxypropionate Group C solvent: γ-butyrolactone, ethylene carbonate, propylene carbonate and cyclohexanone

  (3) The positive resist composition as described in (1) or (2), wherein the resin as the component (A) has a monocyclic or polycyclic alicyclic hydrocarbon structure.

  (4) A pattern forming method comprising the steps of: forming a resist film from the positive resist composition according to any one of (1) to (3); and exposing and developing the resist film.

The preferred embodiments of the present invention will be further described below.
(5) (B-1) A triarylsulfonium salt having a fluorine atom in the cation moiety that generates an aliphatic or aromatic sulfonic acid having a fluorine atom by irradiation with actinic rays or radiation is represented by the following general formula (BI). The positive resist composition according to any one of (1) to (3), wherein the positive resist composition is represented by:

In the general formula (BI), R ₁ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, an alkoxy group, a halogen atom or a phenylthio group. When there are a plurality of R _{1 s} , R _{1 s} may be the same or different. However, at least one of R ₁ is substituted with a fluorine atom or an alkyl group substituted with a fluorine atom, an alicyclic hydrocarbon group substituted with a fluorine atom, an alkoxy group substituted with a fluorine atom, or a fluorine atom. Represents a phenylthio group. y1 represents 0-5 independently of each other. Q ₁ represents an alkyl group substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom or an aryl group substituted with a fluorinated alkyl group.

  (6) (B-2) A sulfonium salt which does not have a fluorine atom in the cation moiety and generates an aliphatic or aromatic sulfonic acid having a fluorine atom by irradiation with actinic rays or radiation is represented by the following general formula (BII) or ( (BIII) The positive resist composition as described in any one of (1) to (3) and (5) above.

In General Formulas (BII) and (BIII), R ₂ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, or an alkoxy group. When R ₂ is in plurality, R ₂ may each be the same or different. Q ₂ represents an alkyl group substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom or an aryl group substituted with a fluorinated alkyl group. y2 represents 0-5 independently of each other. R ₃ represents an alkyl group or an alicyclic hydrocarbon group. When there are a plurality of R _{3 s} , R _{3 s} may be the same or different. When there are a plurality of R _{3 s} , R ₃ may be bonded to each other to form a ring. R ₄ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, or an alkoxy group. When there are a plurality of R _{4 s} , R _{4 s} may be the same or different. A represents an aromatic group or a heterocyclic group. Q ₃ represents an alkyl group substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom, or an aryl group substituted with a fluorinated alkyl group. Xa represents 1-3. y3 represents 0-5 independently of each other.

  (7) The resin as component (A) has a repeating unit having an alkali-soluble group protected by a 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group (3) The positive resist composition as described in any one of (5) and (6).

  (8) The positive type according to any one of (3) and (5) to (7), wherein at least one of the alicyclic hydrocarbon structures of the resin as the component (A) is dihydroxyadamantane Resist composition.

(9) The (A) component resin has the following four types of repeating units (A-1) to (A-4): (1) to (3) and (5) to (8) The positive resist composition according to any one of the above.
(A-1) At least one repeating unit selected from repeating units represented by the following general formula (I):
(A-2) at least one type of repeating unit selected from repeating units having groups represented by the following general formulas (II-1) to (II-4);
(A-3) at least one repeating unit selected from repeating units represented by the following general formula (III) and (A-4) 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group At least one repeating unit selected from repeating units having an alkali-soluble group protected by.

In general formula (I), R _1a represents a hydrogen atom or a methyl group. W ₁ represents a single bond or a divalent linking group.

In General Formulas (II-1) to (II-4), R _{1b to} R _5b each independently represent 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 formula (III), R _1c represents a hydrogen atom or a methyl group. R _{2c to} R _4c each independently represents a hydrogen atom or a hydroxyl group. However, at least one of R _{2c to} R _4c represents a hydroxyl group.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a positive resist composition having a rectangular profile with high sensitivity, high resolution, small particle initial value, and excellent curvature reproducibility, and a pattern forming method using the same.

Hereinafter, the present invention will be described in detail.
In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes the thing which has a substituent with the thing which 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 whose solubility in an alkaline developer is increased by the action of an acid The positive resist composition of the present invention contains a resin whose solubility in an alkaline developer is increased by the action of an acid.
When the positive resist composition of the present invention is irradiated with ArF excimer laser light, the resin whose solubility in an alkaline developer is increased by the action of an acid has a monocyclic or polycyclic alicyclic hydrocarbon structure, A resin whose solubility in an alkaline developer is increased by the action of an acid (hereinafter also referred to as “alicyclic hydrocarbon-based acid-decomposable resin”) is preferable.
The alicyclic hydrocarbon-based acid-decomposable resin has, for example, a repeating unit having a partial structure containing an alicyclic hydrocarbon represented by the following general formula (pI) to general formula (pVI) and is alkalinized by the action of an acid. Resins that increase the solubility in the developer are preferred.

In the formula, R ₁₁ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a sec-butyl group, and Z forms an alicyclic hydrocarbon group together with a carbon atom. Represents the atomic group necessary to do.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or alicyclic hydrocarbon group having 1 to 4 carbon atoms, provided that at least one of R _{12 to} R ₁₄ , or Either R ₁₅ or R ₁₆ represents an alicyclic hydrocarbon group.
R _{17 to} R ₂₁ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group, provided that at least one of R _{17 to} R ₂₁ Represents an alicyclic hydrocarbon group. Moreover, either R <_19> , R < ₂₁ > represents a C1-C4 linear or branched alkyl group or alicyclic hydrocarbon group.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or an alicyclic hydrocarbon group, provided that at least one of R _{22 to} R ₂₅ Represents an alicyclic hydrocarbon group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

In the general formulas (pI) to (pVI), the alkyl group in R _{12 to} R ₂₅ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group.
Further, the further substituent of the alkyl group includes an alkoxy group having 1 to 4 carbon atoms, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an acyl group, an acyloxy group, a cyano group, a hydroxyl group, A carboxy group, an alkoxycarbonyl group, a nitro group, etc. can be mentioned.

The alicyclic hydrocarbon group in R _{11 to} R _{25 or} the alicyclic hydrocarbon group formed by Z and a carbon atom may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25. These alicyclic hydrocarbon groups may have a substituent.
Below, the structural example of an alicyclic part is shown among alicyclic hydrocarbon groups.

  In the present invention, preferred examples of the alicyclic moiety include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclohexyl group, cycloheptyl. Group, cyclooctyl group, cyclodecanyl group and cyclododecanyl group. More preferred are an adamantyl group, a decalin residue, a norbornyl group, a cedrol group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group, and a cyclododecanyl group.

Examples of the substituent for these alicyclic hydrocarbon groups include an alkyl group, a halogen atom, a hydroxyl group, an alkoxy group, a carboxyl group, and an alkoxycarbonyl group. The alkyl group is preferably a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group or a butyl group, more preferably a methyl group, an ethyl group, a propyl group or an isopropyl group. Examples of the alkoxy group include those having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. The alkyl group and the alkoxy group may have a further substituent. Examples of further substituents on the alkyl group and alkoxy group include a hydroxyl group, a halogen atom, and an alkoxy group.

The structures represented by the general formulas (pI) to (pVI) in the resin can be used for protecting alkali-soluble groups. Examples of the alkali-soluble group include various groups known in this technical field.
Specific examples include a carboxylic acid group, a sulfonic acid group, a phenol group, and a thiol group, and a carboxylic acid group and a sulfonic acid group are preferable.
Preferred examples of the alkali-soluble group protected by the structure represented by the general formulas (pI) to (pVI) in the resin include groups represented by the following general formulas (pVII) to (pXI).

Here, R _{11 to} R _{25 and} Z are the same as defined above.
In the resin, the repeating unit having an alkali-soluble group protected by the structure represented by the general formulas (pI) to (pVI) is preferably a repeating unit represented by the following general formula (pA).

Here, 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. The alkyl group as R may have a substituent such as an alkoxy group (preferably having 3 or less carbon atoms).
A is a single bond, a group selected from the group consisting of 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. The alkylene group as A may have a substituent having preferably 5 or less carbon atoms such as an alkyl group or an alkoxy group.
Ra represents any group of the above formulas (pI) to (pVI).
Ra preferably represents a 2-alkyl-2-adamantyl group or a 1-adamantyl-1-alkylalkyl group. The alkyl group in these groups preferably has 1 to 8 carbon atoms, and more preferably 1 to 3 carbon atoms.

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

The alicyclic hydrocarbon-based acid-decomposable resin may have a repeating unit having an alkali-soluble group protected by a 2-alkyl-2-adamantyl group such as a repeating unit formed by the monomers 1 to 4 and 32. preferable.
The alicyclic hydrocarbon-based acid-decomposable resin preferably has a repeating unit having an alkali-soluble group protected by a 1-adamantyl-1-alkylalkyl group, such as the repeating unit formed by the monomers 5 to 8. .

The resin according to the present invention contains a group (hereinafter also referred to as “acid-decomposable group”) that is insoluble or hardly soluble in alkali and decomposes by the action of an acid to become alkali-soluble.
The acid-decomposable group is a repeating unit having a partial structure containing an alicyclic hydrocarbon represented by the general formula (pI) to the general formula (pVI), and at least one repeating unit among the repeating units of the copolymerization component described later. It can be contained in the unit.

The structure of the acid-decomposable group is represented by _{-C (= O) -X 1 -R} 0.
In the formula, R ₀ is a tertiary alkyl group such as t-butyl group or t-amyl group, isobornyl group, 1-ethoxyethyl group, 1-butoxyethyl group, 1-isobutoxyethyl group, 1-cyclohexyloxy 1-alkoxyethyl group such as ethyl group, 1-methoxymethyl group, alkoxymethyl group such as 1-ethoxymethyl group, 3-oxoalkyl group, tetrahydropyranyl group, tetrahydrofuranyl group, trialkylsilyl ester group, 3- An oxocyclohexyl ester group, a 2-methyl-2-adamantyl group, a mevalonic lactone residue and the like can be mentioned. X ₁ represents an oxygen atom, a sulfur atom, -NH -, - NHSO ₂ - or an -NHSO ₂ NH-.

  The alicyclic hydrocarbon-based acid-decomposable resin preferably further has a repeating unit having a group represented by the following general formula (IIIA).

In general formula (IIIA), R _{2c to} R _4c each independently represents a hydrogen atom or a hydroxyl group. However, at least one of R _{2c to} R _4c represents a hydroxyl group.

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

  Examples of the repeating unit having a group represented by the general formula (IIIA) include a repeating unit represented by the following general formula (III).

In general formula (III), R _1c represents a hydrogen atom or a methyl group.
R _{2c to} R _4c each independently represents a hydrogen atom or a hydroxyl group. However, at least one of R _{2c to} R _4c represents a hydroxyl group.

  Although the specific example of the repeating unit which has a structure represented by general formula (IIIA) below is given, it is not limited to these.

  The alicyclic hydrocarbon-based acid-decomposable resin can further contain a repeating unit having a lactone structure represented by the following general formula (IV).

In general formula (IV), R ₁ a represents a hydrogen atom or a methyl group.
W ₁ represents a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, or a group of two or more groups selected from the group consisting of an ester group.
Ra ₁ , Rb ₁ , Rc ₁ , Rd ₁ , Re ₁ each independently represents 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 _{1 to} Re ₁ 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. Can do.

In general formula (IV), examples of the alkylene group for W ₁ include groups represented by the following formulae.
− [C (Rf) (Rg)] r ₁ −
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. The alkyl group and the alkoxy group may have a further substituent. Examples of further substituents on 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 ₁ is an integer of 1 to 10.

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

In the specific example of the general formula (IV), (IV-17) to (IV-36) are preferable because the exposure margin becomes better.
Further, as the structure of the general formula (IV), those having an acrylate structure are preferable from the viewpoint that the edge roughness becomes good.

  The alicyclic hydrocarbon-based acid-decomposable resin may further contain a repeating unit having a group represented by any one of the following general formulas (II-1) to (II-4).

In General Formulas (II-1) to (II-4), R _{1b to} R _5b each independently represent 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 (II-1) to (II-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 addition, R _<1b > -R < _5b > in general formula (II-1)-(II-4) may be connected with any of the carbon atoms which comprise 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 (II-1) to (II-4) include a repeating unit represented by the following general formula (II).

In general formula (II), _Rb0 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 (II-1) to (II-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 preferably represents 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 (II-1) to (II-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, and 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. The alkyl group and the alkoxy group may have a further substituent. Examples of further substituents on 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. 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.

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

  The alicyclic hydrocarbon-based acid-decomposable resin can further contain a repeating unit represented by the following general formula (V).

In the general formula (V), A ₆ represents a single bond, an alkylene group, a cycloalkylene group, an ether group, a thioether group, a carbonyl group, or a group of two or more groups selected from the group consisting of ester groups.
R _6a represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, or a halogen atom.

In the general formula (V), the alkylene group of A _6, can be a group represented by the following formula.
-[C (Rnf) (Rng)] r-
In the above formula, Rnf and Rng represent a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, and 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. The alkyl group and the alkoxy group may have a further substituent. Examples of further substituents on 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 (V), Examples of the cycloalkylene group A _6, include those having 3 to 10 carbon atoms, mention may be made of a cyclopentylene group, cyclohexylene group, a cyclooctylene group.

The bridged alicyclic ring containing Z ₆ 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, a propylcarbonyloxy group, a benzoyloxy group), an alkyl group (preferably having a carbon number of 1 to 4), a carboxyl group, a hydroxyl group, an alkylsulfonylsulfamoyl group (such as —CONHSO ₂ CH ₃ ) can be mentioned. Note that 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 (V), the oxygen atom of the ester group bonded to A ₆ may be bonded at any position of the carbon atom constituting the bridged alicyclic ring structure containing Z ₆ .

  Although the specific example of the repeating unit represented by general formula (V) below is given, it is not limited to these.

  The alicyclic hydrocarbon-based acid-decomposable resin may have a repeating unit represented by the following general formula (I).

In general formula (I), R _1a represents a hydrogen atom or a methyl group. W ₁ represents a single bond or a divalent linking group.

Examples of the divalent linking group for W ₁ include a single group selected from the group consisting of an alkylene group, an ether group, a thioether group, a carbonyl group, and an ester group, or a combination of two or more of these groups. Can do.

In the general formula (I), examples of the alkylene group for W ₁ include groups represented by the following formulae.
− [C (Rf) (Rg)] r ₁ −
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 further substituents on 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 ₁ is an integer of 1 to 10.

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

  In addition to the above repeating units, the alicyclic hydrocarbon-based acid-decomposable resin as component (A) has dry etching resistance, standard developer suitability, substrate adhesion, resist profile, and general necessary characteristics of resist. Various repeating units can be contained for the purpose of adjusting a certain resolution, heat resistance, sensitivity and the like.

Examples of such a repeating unit include, but are not limited to, repeating units corresponding to the following monomers.
Thereby, the performance required for the acid-decomposable resin, in particular,
(1) Solubility in coating solvent,
(2) Film formability (glass transition point),
(3) Alkali developability,
(4) Membrane slip (hydrophobic, alkali-soluble group selection),
(5) Adhesion of unexposed part to substrate,
(6) Dry etching resistance,
Etc. can be finely adjusted.
As such a monomer, for example, a compound having one addition polymerizable unsaturated bond selected from acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, etc. Etc.

Specifically, the following monomers can be mentioned.
Acrylic acid esters (preferably alkyl acrylates having an alkyl group with 1 to 10 carbon atoms):
Methyl acrylate, ethyl acrylate, propyl acrylate, amyl acrylate, cyclohexyl acrylate, ethyl hexyl acrylate, octyl acrylate, tert-octyl acrylate, chloroethyl acrylate, 2-hydroxyethyl acrylate 2,2-dimethylhydroxy Propyl acrylate, 5-hydroxypentyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, and the like.

Methacrylic acid esters (preferably alkyl methacrylate having 1 to 10 carbon atoms in the alkyl group):
Methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 2 , 2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate and the like.

Acrylamides:
Acrylamide, N-alkylacrylamide (alkyl group having 1 to 10 carbon atoms, such as methyl group, ethyl group, propyl group, butyl group, t-butyl group, heptyl group, octyl group, cyclohexyl group, hydroxyethyl group, etc. N, N-dialkylacrylamide (alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, butyl, isobutyl, ethylhexyl, cyclohexyl, etc.), N-hydroxy Ethyl-N-methylacrylamide, N-2-acetamidoethyl-N-acetylacrylamide and the like.

Methacrylamides:
Methacrylamide, N-alkylmethacrylamide (alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, t-butyl, ethylhexyl, hydroxyethyl, cyclohexyl, etc.), N, N -Dialkylmethacrylamide (there are alkyl groups such as ethyl group, propyl group, butyl group), N-hydroxyethyl-N-methylmethacrylamide and the like.

Allyl compounds:
Allyl esters (for example, allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, etc.), allyloxyethanol and the like.

Vinyl ethers:
Alkyl vinyl ethers (eg hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethyl hexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether, Diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether and the like.

Vinyl esters:
Vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxyacetate, vinyl acetoacetate, vinyl lactate, vinyl -Β-phenylbutyrate, vinylcyclohexylcarboxylate and the like.

Dialkyl itaconates:
Dimethyl itaconate, diethyl itaconate, dibutyl itaconate, etc.
Dialkyl esters or monoalkyl esters of fumaric acid; dibutyl fumarate and the like.

  Others include crotonic acid, itaconic acid, maleic anhydride, maleimide, acrylonitrile, methacrylonitrile, maleilonitrile and the like.

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

  In the alicyclic hydrocarbon-based acid-decomposable resin, the content molar ratio of each repeating unit is the resist dry etching resistance, the standard developer suitability, the substrate adhesion, the resist profile, and the resolving power, which is a general required performance of the resist, It is appropriately set for adjusting heat resistance, sensitivity, and the like.

The alicyclic hydrocarbon-based acid-decomposable resin preferably has the following four types of repeating units (A-1) to (A-4).
(A-1) at least one type of repeating unit selected from the repeating units represented by the general formula (I),
(A-2) at least one type of repeating unit selected from repeating units having groups represented by general formulas (II-1) to (II-4);
(A-3) at least one repeating unit selected from the repeating units represented by the general formula (III) and (A-4) 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group At least one repeating unit selected from repeating units having an alkali-soluble group protected by.

  In the alicyclic hydrocarbon-based acid-decomposable resin, the content of the repeating unit having a partial structure containing the alicyclic hydrocarbon represented by the general formulas (pI) to (pVI) is 30 to 70 mol in all repeating units. % Is preferable, more preferably 35 to 65 mol%, still more preferably 40 to 60 mol%.

Further, the content of the repeating unit based on the monomer of the further copolymer component in the resin can be appropriately set according to the performance of the desired resist. Generally, the general formula (pI) 99 mol% or less is preferable with respect to the number of moles of the repeating unit having a partial structure containing an alicyclic hydrocarbon represented by (pVI), more preferably 90 mol% or less, and still more preferably 80 mol% or less. is there.
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.

  In the alicyclic hydrocarbon-based acid-decomposable resin, the content of the repeating unit having an acid-decomposable group is preferably from 15 to 50 mol%, more preferably from 20 to 40 mol%, based on all repeating units.

In the alicyclic hydrocarbon-based acid-decomposable resin having the above four types of repeating units (A-1) to (A-4), the content of the repeating unit (A-1) is based on the total repeating units. 20 to 70 mol% is preferable, and 25 to 60 mol% is more preferable.
The content of the repeating unit (A-2) is preferably from 20 to 70 mol%, more preferably from 25 to 60 mol%, based on all repeating units.
As for content of a repeating unit (A-3), 5-50 mol% is preferable with respect to all the repeating units, More preferably, it is 10-40 mol%, More preferably, it is 15-35 mol%.
As for content of a repeating unit (A-4), 30-70 mol% is preferable with respect to all the repeating units, More preferably, it is 35-65 mol%, More preferably, it is 40-60 mol%.

The alicyclic hydrocarbon-based acid-decomposable resin used in the present invention can be synthesized according to a conventional method (for example, radical polymerization). For example, as a general synthesis method, monomer species are charged into a reaction vessel in a batch or in the course of reaction, and if necessary, a reaction solvent such as ethers such as tetrahydrofuran, 1,4-dioxane, diisopropyl ether, methyl ethyl ketone, A ketone such as methyl isobutyl ketone, an ester solvent such as ethyl acetate, and further dissolved in a solvent that dissolves the composition of the present invention such as propylene glycol monomethyl ether acetate described later, and then nitrogen, argon, etc. Polymerization is started using a commercially available radical initiator (azo initiator, peroxide, etc.) as necessary under an inert gas atmosphere. 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 usually 20% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more. The reaction temperature is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 50 to 100 ° C.

The repeating structural units represented by the above specific examples may be used singly or in combination.
In the present invention, the resins may be used alone or in combination.

The weight average molecular weight of the resin according to the present invention is usually 1,000 to 200,000, more preferably 3,000 to 20,000, as a polystyrene-converted value by the GPC method.
The dispersity (Mw / Mn) is usually 1 to 10, preferably 1 to 5, and more preferably 1 to 4. The smaller the degree of dispersion, the smoother the resolution, resist shape, and resist pattern side walls, and the better the roughness.

  In the positive resist composition of the present invention, the blending amount of all the resins according to the present invention in the entire composition is preferably 40 to 99.99% by mass, more preferably 50 to 99.97, based on the total solid content of the resist. % By mass.

[2] (B-1) A triarylsulfonium salt having a fluorine atom in the cation moiety that generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation. The positive resist composition of the present invention comprises: And a triarylsulfonium salt having a fluorine atom in the cation moiety, which generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with an actinic ray or radiation.
The triarylsulfonium salt having a fluorine atom in the cation moiety that generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation is preferably represented by the following general formula (BI).

In General Formula (BI), R ₁ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, an alkoxy group, a halogen atom, or a phenylthio group. When there are a plurality of R _{1 s} , R _{1 s} may be the same or different. However, at least one of R ₁ is substituted with a fluorine atom or an alkyl group substituted with a fluorine atom, an alicyclic hydrocarbon group substituted with a fluorine atom, an alkoxy group substituted with a fluorine atom, or a fluorine atom. Represents a phenylthio group. y1 represents 0-5 independently of each other. Q ₁ represents an alkyl group substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom or an aryl group substituted with a fluorinated alkyl group.

In general formula (BI), the alkyl group of R ₁ is preferably an alkyl group having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, or a sec-butyl group. And linear or branched alkyl groups such as t-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, etc. it can. The alkyl group of R ₁ may be connected to the benzene ring via an oxygen atom, a sulfur atom, —C (═O) —, —NH—, or a combination thereof.
The alicyclic hydrocarbon group of R ₁ is preferably an alicyclic hydrocarbon group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, and a norbornyl group.
Examples of the alkoxy group for R ₁ include an alkoxy group corresponding to the above alkyl group.
Examples of the halogen atom for R ₁ include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom is preferred.

The alkyl group, alicyclic hydrocarbon group, alkoxy group, phenylthio group and the like of R ₁ may have a substituent. Examples of the substituent that the alkyl group, alicyclic hydrocarbon group, alkoxy group, phenylthio group and the like of R ₁ may have include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), hydroxyl group, alkyl Groups, alkoxy groups, alkylthio groups and the like.

In the general formula (BI), at least one of R ₁ is a fluorine atom or an alkyl group substituted with a fluorine atom, an alicyclic hydrocarbon group substituted with a fluorine atom, or an alkoxy group substituted with a fluorine atom. Alternatively, it is a phenylthio group substituted with a fluorine atom.
R ₁ is preferably a fluorine atom or an alkyl group substituted with a fluorine atom. The alkyl group substituted with a fluorine atom is the above alkyl group substituted with a fluorine atom, for example, perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluorohexyl group, A perfluorooctyl group etc. can be mentioned.

In the general formula (BI), the total number of fluorine atoms contained in (R ₁ ) _y1 is 4 or more, preferably 4 to 27, and more preferably 4 to 18.

The alkyl group in Q ₁ is preferably an alkyl group having 1 to 30 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, pentyl. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc. Can be mentioned.
The cycloalkyl group in Q ₁ is preferably a cycloalkyl group having 3 to 30 carbon atoms, such as cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group, boronyl group and the like. .
Preferred examples of the aryl group for Q ₁ include aryl groups having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, and a naphthyl group.
The alkyl group, cycloalkyl group or aryl group as Q ₁ has a fluorine atom, and the preferred number of fluorine atoms is 1 to 20, more preferably 3 to 8.
The fluorinated alkyl group of the aryl group as Q ₁ is preferably a fluorinated alkyl group having 1 to 5 carbon atoms, such as a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a pentafluoroethyl group, etc. Can be mentioned.
In the alkyl group in Q _1, a cycloalkyl group, an aryl group which aryl group or a fluorine alkyl group is substituted may further have a substituent. Examples of the further substituent include a halogen atom (excluding a fluorine atom), an alkyl group, an alkoxy group, and an alkylthio group.

  Hereinafter, although the specific example of a compound represented by general formula (BI) is given, this invention is not limited to this.

  The content of the triarylsulfonium salt having a fluorine atom in the cation moiety that generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation is usually 0 with respect to the total solid content of the resist composition. .10 to 30% by mass, preferably 0.50 to 20% by mass.

[3] (B-2) A sulfonium salt that generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation, and does not have a fluorine atom in the cation moiety. The positive resist composition of the present invention comprises: Furthermore, the sulfonium salt which does not have a fluorine atom in a cation part which generate | occur | produces the aliphatic or aromatic sulfonic acid which has a fluorine atom by irradiation of actinic light or a radiation is contained.
The sulfonium salt that does not have a fluorine atom in the cation moiety and generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation may be represented by the following general formula (BII) or (BIII). preferable.

In General Formulas (BII) and (BIII), R ₂ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, or an alkoxy group. When there are a plurality of R _{2 s} , R _{2 s} may be the same or different. Q ₂ represents an alkyl group substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom or an aryl group substituted with a fluorinated alkyl group. y2 represents 0-5 independently of each other. R ₃ represents an alkyl group or an alicyclic hydrocarbon group. When R ₃ is in plurality, R ₃ may each be the same or different. When there are a plurality of R _{3 s} , R ₃ may be bonded to each other to form a ring. R ₄ represents an alkyl group, an alicyclic hydrocarbon group, a hydroxyl group, a carboxyl group, or an alkoxy group. When there are a plurality of R _{4 s} , R _{4 s} may be the same or different. A represents an aromatic group or a heterocyclic group. Q ₃ represents an alkyl group substituted with a fluorine atom, a cycloalkyl group substituted with a fluorine atom, an aryl group substituted with a fluorine atom, or an aryl group substituted with a fluorinated alkyl group. Xa represents 1-3. y3 represents 0-5 independently of each other.

In the general formulas (BII) and (BIII), examples of the alkyl group represented by R _{2 to} R _{4 can be the same as} the alkyl group represented by R _{1 in} the general formula (BI).
Examples of the alicyclic hydrocarbon group represented by R _{2 to} R ₄ include the same alicyclic hydrocarbon groups represented by R _{1 in} the general formula (BI).
Examples of the alkoxy group for R ₂ and R ₄ include the same alkoxy groups as those for R _{1 in} formula (BI).
The alkyl groups of R ₂ and R ₄ include those linked to the benzene ring via an oxygen atom, a sulfur atom, —C (═O) —, —NH—, or a combination thereof.
The alkyl group of R ₃ is further an alkyl group (preferably having 1 to 15 carbon atoms), an aryl group (preferably a phenyl group), an alicyclic group via a carbonyl group, an ether group, a thioether group, a phenylene group or a combination thereof Including those linked to a hydrocarbon group (preferably having 6 to 15 carbon atoms). The alkyl group and alicyclic hydrocarbon group of R ₃ further include those having a substituent such as a hydroxyl group or an alkoxy group. The alkyl group of R ₃ may further have an alicyclic hydrocarbon group or an aryl group as a substituent. The alicyclic hydrocarbon group for R ₃ further includes an alkyl group, an aryl group, and ═O as a substituent.
When R ₃ is the presence of two or more groups, when two of them bonded to each other to form a ring, the two groups R ₃ are formed by linking each other, be, for example, a butylene group, etc. it can.

  The aromatic group or heterocycle as A (ring containing a heteroatom such as oxygen, sulfur or nitrogen atom in the ring) may be monocyclic or polycyclic, and preferably has 5 to 20 carbon atoms. Examples thereof include a benzene ring, a furan ring, a thiophene ring, a benzofuran ring, a benzothiophene ring, a naphthalene ring, and an anthracene ring.

Q ₂ and Q ₃ are the same as Q ₁ in the general formula (BI).

  Specific examples of the compounds represented by the general formulas (BII) to (BIII) are shown below, but are not limited thereto.

The compounds represented by the general formulas (BII) to (BIII) can be synthesized by a known method. A compound represented by the general formula (III), for example, a compound of III-21, is obtained by reacting a phenacyl halide derivative such as phenacyl bromide with sulfide in a suitable solvent in the absence of a catalyst or a silver catalyst, After obtaining the phenacyldialkylsulfonium salt, it can be obtained by salt exchange with the corresponding anion. Other compounds can be similarly obtained from the corresponding halogenide derivative and sulfide by the above procedure.
The compound represented by formula (BII) can be synthesized in the same manner as described in JP-A 2000-47387, page 36, paragraph [0098], paragraph 16-27, about the sulfonium compound.

The content of the sulfonium salt that does not have a fluorine atom in the cation moiety and generates an aliphatic or aromatic sulfonic acid having a fluorine atom upon irradiation with actinic rays or radiation is usually 0. It is 10-25 mass%, Preferably it is 0.50-23 mass%, More preferably, it is 1.0-20 mass%.

[4] Other compounds that generate acid upon irradiation with actinic rays or radiation The positive resist composition of the present invention may further include other compounds (photoacid generator) as compounds that generate acid upon irradiation with actinic rays or radiation. Agent).
Examples of such photoacid generators include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, actinic rays used in microresists, etc. Known compounds that generate an acid upon irradiation with radiation and mixtures thereof can be appropriately selected and used.

  For example, onium salts such as diazonium salts, ammonium salts, phosphonium salts, iodonium salts, selenonium salts, arsonium salts, etc., organic halogen compounds, organic metal / organic halides, photoacid generators having o-nitrobenzyl type protecting groups, iminosulfonates Examples thereof include a compound that generates photosulfonic acid by photolysis, such as disulfide, and a disulfone compound.

  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 as described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  Of the other compounds that decompose upon irradiation with actinic rays or radiation to generate an acid, those that are effectively used will be described below.

  (1) An iodonium salt represented by the following general formula (PAG1)

Here, the formulas Ar ¹ and Ar ² each independently represent an aryl group. Preferable substituents for Ar ¹ and Ar ² include an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, a nitro group, a carboxyl group, an alkoxycarbonyl group, a hydroxy group, a mercapto group, and a halogen atom.

Z ⁻ represents a counter anion, and examples thereof include perfluoroalkanesulfonic acid anions such as BF ₄ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , SiF ₆ ²⁻ , ClO ₄ ⁻ and CF ₃ SO ₃ ⁻ , pentafluoro Examples include, but are not limited to, condensed polynuclear aromatic sulfonate anions such as benzenesulfonate anion and naphthalene-1-sulfonate anion, anthraquinone sulfonate anion, and sulfonate group-containing dyes.

Ar ¹ and Ar ² may be bonded through a single bond or a substituent.

  Specific examples include the following compounds, but are not limited thereto.

The above onium salt represented by the general formula (PAG1) is known, for example, by the methods described in U.S. Pat. Nos. 2,807,648 and 4,247,473, and JP-A-53-101,331. Can be synthesized.

  (2) A disulfone derivative represented by the following general formula (PAG3) or an iminosulfonate derivative represented by the general formula (PAG4)

In the formula, Ar ³ and Ar ⁴ each independently represents an aryl group.
R ²⁰⁶ represents an alkyl group or an aryl group. A represents an alkylene group, an alkenylene group or an arylene group.
Specific examples include the following compounds, but are not limited thereto.

  (3) Diazodisulfone derivative represented by the following general formula (PAG5)

Here, R represents an alkyl group, a cycloalkyl group, or an aryl group.
Specific examples include the following compounds, but are not limited thereto.

The content of other compounds that generate an acid upon irradiation with actinic rays or radiation is usually 0.10 to 25% by mass, preferably 0.50 to 23% by mass, more preferably based on the total solid content of the resist composition. Is 1.0 to 20% by mass.

[5] (D) Organic solvent The positive resist composition of the present invention is preferably used by mixing two or more organic solvents as a solvent. As the mixed solvent, at least one selected from propylene glycol monoalkyl ether carboxylate (also referred to as group A solvent) and at least one selected from propylene glycol monoalkyl ether, alkyl lactate and alkyl alkoxypropionate (group B). And / or a mixed solvent containing at least one selected from γ-butyrolactone, ethylene carbonate, propylene carbonate, and cyclohexanone (also referred to as a group C solvent). That is, as a mixed solvent, a combination of a group A solvent and a group B solvent, a combination of a group A solvent and a group C solvent, a combination of a group A solvent, a group B solvent, and a group C solvent. Can be used.

  Preferred examples of the propylene glycol monoalkyl ether carboxylate include propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether acetate, and propylene glycol monoethyl ether propionate.

  Preferred examples of the propylene glycol monoalkyl ether include propylene glycol monomethyl ether and propylene glycol monoethyl ether. Preferable examples of the alkyl lactate include methyl lactate and ethyl lactate. Preferred examples of the alkyl alkoxypropionate include ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, and methyl 3-ethoxypropionate.

The mass ratio (A: B) of the group A solvent and the group B solvent is preferably 90:10 to 15:85, more preferably 85:15 to 20:80, and still more preferably 80:20. ~ 25: 75.
The use mass ratio (A: C) of the solvent of the group A and the solvent of the group C is preferably 99.9: 0.1 to 75:25, more preferably 99: 1 to 80:20, and still more preferably. Is 97: 3-85: 15.

In the case of combining these three solvents, the mass ratio of the group C solvent is preferably from 0.1 to 25 mass%, more preferably from 1 to 20 mass%, still more preferably from 3 to 3 mass% based on the total solvent. 17% by mass.
In the present invention, the solid content of the composition containing the above components is preferably dissolved in the mixed solvent in a solid content concentration of 3 to 25% by mass, more preferably 5 to 22% by mass, and still more preferably 7 ˜20 mass%.

As a preferable combination of the mixed solvent containing propylene glycol monoalkyl ether carboxylate in the present invention,
Propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether Propylene glycol monomethyl ether acetate + ethyl lactate Propylene glycol monomethyl ether acetate + 3-ethoxyethyl propionate Propylene glycol monomethyl ether acetate + γ-butyrolactone Propylene glycol monomethyl ether acetate + ethylene carbonate Propylene glycol monomethyl ether Acetate + propylene carbonate Propylene glycol monomethyl ether acetate + cyclohexanone Propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether + γ-butyrolactone Propylene glycol monomethyl ether acetate Ethyl lactate + γ-butyrolactone Propylene glycol monomethyl ether acetate + 3-ethoxyethyl propionate + γ-butyrolactone Propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether + ethylene carbonate Propylene glycol monomethyl ether acetate + ethyl lactate + ethylene carbonate Propylene glycol monomethyl ether acetate + 3 -Ethoxyethyl propionate + ethylene carbonate propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether + propylene carbonate propylene glycol monomethyl ether acetate + ethyl lactate + propylene carbonate propylene glycol monomethyl ether Acetate + 3-ethoxyethylpropionate + propylene carbonate propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether + cyclohexanone.

Particularly preferred solvent combinations include:
Propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether Propylene glycol monomethyl ether acetate + propylene glycol monomethyl ether + γ-butyrolactone Propylene glycol monomethyl ether acetate + ethyl lactate + γ-butyrolactone Propylene glycol monomethyl ether acetate + 3-ethoxyethyl propionate + γ-butyrolactone Propylene Glycol monomethyl ether acetate + propylene glycol monomethyl ether + ethylene carbonate Propylene glycol monomethyl ether acetate + ethyl lactate + ethylene carbonate Propylene glycol monomethyl ether acetate + 3-ethoxyethyl propionate + ethylene carbonate Bonate Propylene glycol monomethyl ether acetate + Propylene glycol monomethyl ether + Propylene carbonate Propylene glycol monomethyl ether acetate + Ethyl lactate + Propylene carbonate Propylene glycol monomethyl ether acetate + 3-Ethoxyethyl propionate + Propylene carbonate Propylene glycol monomethyl ether acetate + Propylene glycol monomethyl ether + Cyclohexanone propylene glycol monomethyl ether acetate + cyclohexanone.

Other solvents may be added to each of the above mixed solvents. Generally the addition amount of such other solvent is 30 mass parts or less with respect to 100 mass parts of each mixed solvent of this invention. As other solvents, in addition to the solvents exemplified as the essential solvents for each of the above mixed solvents, ethylene dichloride, cyclopentanone, methyl ethyl ketone, toluene, N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran and the like Can be mentioned.

  The positive resist composition of the present invention preferably uses the above-mentioned mixed solvent, but if necessary, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, cyclohexanone, etc. can be used as a single solvent.

  The solid content concentration in the positive resist composition is preferably 5 to 15% by mass, and more preferably 7 to 11% by mass.

[6] (C) Nitrogen-containing basic compound Next, the (C) nitrogen-containing basic compound that can be preferably used in the positive resist composition of the present invention will be described. (C) As the nitrogen-containing basic compound, an organic amine, a basic ammonium salt, a basic sulfonium salt, or the like may be used as long as it does not deteriorate sublimation or resist performance.
Among these nitrogen-containing basic compounds, organic amines are preferable in terms of excellent image performance.
For example, Japanese Patent Laid-Open Nos. 63-149640, 5-24962, 5-127369, 5-289322, 5-249683, 5-289340, and 5-232706. JP-A-5-257282, JP-A-6-242605, JP-A-6-242606, JP-A-6-266100, JP-A-6-266110, JP-A-6-317902, JP-A-7-120929, JP-A-7-146558, JP-A-7-319163, JP-A-7-508840, JP-A-7-333844, JP-A-7-219217, JP-A-7-92678, JP-A-7-28247, Special Kaihei 8-22120, JP-A-8-110638, JP-A-8-123030, JP-A-9-274312, JP-A-9-1 No. 6871, JP-A-9-292708, JP-A-9-325496, Hei No. 7-508840, No. USP5525453, JP USP5629134, it is possible to use a basic compound as described in such Patent USP5667938.

As the nitrogen-containing basic compound, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,4-diazabicyclo is preferable. [2.2.2] Octane, 4-dimethylaminopyridine, 1-naphthylamine, piperidine, hexamethylenetetramine, imidazoles, hydroxypyridines, pyridines, 4,4′-diaminodiphenyl ether, pyridinium p-toluenesulfonate, Examples include 2,4,6-trimethylpyridinium p-toluenesulfonate, tetramethylammonium p-toluenesulfonate, tetrabutylammonium lactate, triethylamine, and tributylamine.
Among these, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,4-diazabicyclo [2.2.2] Organic amines such as octane, 4-dimethylaminopyridine, 1-naphthylamine, piperidine, hexamethylenetetramine, imidazoles, hydroxypyridines, pyridines, 4,4′-diaminodiphenyl ether, triethylamine, and tributylamine are preferred.

(C) Content of nitrogen-containing basic compound is 0.001-10 mass% normally with respect to the total solid of a positive resist composition, Preferably it is 0.001-5 mass%, More preferably, it is 0.00. It is 001-0.5 mass%.
(D) A basic compound can be used individually by 1 type or in combination of 2 or more types.

[7] (E) Fluorine-based and / or silicon-based surfactant The positive resist composition of the present invention further comprises (E) a fluorine-based and / or silicon-based surfactant (fluorine-based surfactant and silicon-based interface). It is preferable to contain any one or two or more of activators and surfactants containing both fluorine atoms and silicon atoms.
When the positive resist composition of the present invention contains the above-mentioned (E) surfactant, when using an exposure light source of 250 nm or less, particularly 220 nm or less, good sensitivity and resolution, and less adhesion and development defects. A resist pattern can be provided.
As these (E) surfactants, for example, JP-A 62-36663, JP-A 61-226746, JP-A 61-226745, JP-A 62-170950, JP No. 63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, JP-A 2002-277862, US Pat. No. 5,405,720 , No. 5,360,692, No. 5,529,881, No. 5,296,330, No. 5,543,098, No. 5,576,143, No. 5,294,511, No. 5,824,451 The following commercially available surfactants can also be used as they are.
Examples of commercially available surfactants that can be used include F-top EF301 and EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430 and 431 (manufactured by Sumitomo 3M Ltd.), MegaFuck F171, F173, F176, F189, and R08. (Dainippon Ink Chemical Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troisol S-366 (Troy Chemical Co., Ltd.), etc. Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

In addition to the known surfactants described above, surfactants are derived from fluoroaliphatic compounds produced by the telomerization method (also referred to as the telomer method) or the oligomerization method (also referred to as the oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.
As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. Or may be block copolymerized. Examples of the poly (oxyalkylene) group include a poly (oxyethylene) group, a poly (oxypropylene) group, a poly (oxybutylene) group, and the like, and a poly (oxyethylene, oxypropylene, and oxyethylene group). A unit having different chain lengths in the same chain length, such as a block linked body) or a poly (block linked body of oxyethylene and oxypropylene) group, may be used. Furthermore, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate (or methacrylate) is not only a binary copolymer but also a monomer having two or more different fluoroaliphatic groups, Further, it may be a ternary or higher copolymer obtained by simultaneously copolymerizing two or more different (poly (oxyalkylene)) acrylates (or methacrylates).
Examples of commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (Dainippon Ink Chemical Co., Ltd.). Further, a copolymer of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxyalkylene)) acrylate (or methacrylate), an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxy) (Ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate) copolymer, acrylate (or methacrylate) with C ₈ F ₁₇ groups (
Copolymer with poly (oxyalkylene)) acrylate (or methacrylate), acrylate (or methacrylate) with C ₈ F ₁₇ groups, (poly (oxyethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) Examples thereof include a copolymer with acrylate (or methacrylate).

(E) The usage-amount of surfactant is 0.0001-2 mass% with respect to positive resist composition whole quantity (except a solvent), More preferably, it is 0.001-1 mass%.

The positive resist composition of the present invention has a low molecular acid decomposability, which has a molecular weight of 2000 or less, if necessary, has a group that can be decomposed by the action of an acid, and alkali solubility increases by the action of an acid. Compounds can be included.
For example, Proc. SPIE, 2724, 355 (1996), JP-A-8-15865, USP5310619, USP-5372912, J. Pat. Photopolym. Sci. , Tech. , Vol. 10, no. 3,511 (1997)), which contains an acid-decomposable group, such as cholic acid derivatives, dehydrocholic acid derivatives, deoxycholic acid derivatives, lithocholic acid derivatives, ursocholic acid derivatives, and abietic acid derivatives. An aromatic compound such as a compound or a naphthalene derivative containing an acid-decomposable group can be used as the low-molecular acid-decomposable compound.
Furthermore, the low-molecular acid-decomposable dissolution inhibiting compound described in JP-A-6-51519 can also be used in an addition range at a level that does not deteriorate the 220 nm permeability, and a 1,2-naphthoquinonediazite compound can also be used.

When the low molecular acid decomposable dissolution inhibiting compound is used in the resist composition of the present invention, the content thereof is usually used in the range of 0.5 to 50% by mass based on the total solid content of the resist composition. Preferably it is 0.5-40 mass%, More preferably, it is 0.5-30 mass%, Most preferably, it is used in 0.5-20.0 mass%.
Addition of these low molecular acid decomposable dissolution inhibiting compounds not only further improves the development defects, but also improves dry etching resistance.

  If necessary, the positive resist composition of the present invention may further include a compound that promotes dissolution in a developer, an antihalation agent, a plasticizer, a surfactant, a photosensitizer, an adhesion assistant, a crosslinking agent, and a photobase. A generator or the like can be contained.

Examples of the dissolution promoting compound that can be used in the present invention include compounds containing two or more phenolic hydroxyl groups described in JP-A-3-206458, one naphthol such as 1-naphthol, or one carboxyl group. Examples thereof include low molecular compounds having a molecular weight of 1000 or less, such as compounds having the above, carboxylic acid anhydrides, sulfonamide compounds and sulfonylimide compounds.
The blending amount of these dissolution promoting compounds is preferably 30% by mass or less, more preferably 20% by mass or less, with respect to the total mass (solid content) of the composition.

  As a suitable antihalation agent, a compound that efficiently absorbs irradiated radiation is preferable, and substituted benzenes such as fluorene, 9-fluorenone, and benzophenone; anthracene, anthracene-9-methanol, anthracene-9-carboxyethyl, phenanthrene , Polycyclic aromatic compounds such as perylene and azylene. Of these, polycyclic aromatic compounds are particularly preferred. These antihalation agents exhibit the effect of improving standing waves by reducing the reflected light from the substrate and reducing the influence of multiple reflection in the resist film.

Moreover, in order to improve the acid generation rate by exposure, a photosensitizer can be added. Suitable photosensitizers include benzophenone, p, p′-tetramethyldiaminobenzophenone, 2-chlorothioxanthone, anthrone, 9-ethoxyanthracene, pyrene, phenothiazine, benzyl, benzoflavine, acetophenone, phenanthrene, benzoquinone, anthraquinone, 1 , 2-naphthoquinone and the like, but are not limited thereto. These photosensitizers can also be used as the antihalation agent.

≪How to use≫
The positive resist composition of the present invention is used by dissolving the above components in (D) an organic solvent, filtering with a filter, and coating on a predetermined support as follows.
That is, the positive resist composition is applied onto a substrate (eg, silicon / silicon dioxide coating) used in the manufacture of precision integrated circuit elements by an appropriate application method such as a spinner or a coater, and heated to form a resist. A film is formed.
Next, the resist film is exposed through a predetermined mask, heated and developed. In this way, a good resist pattern can be obtained. Here, the exposure light is preferably far ultraviolet rays having a wavelength of 250 nm or less, more preferably 220 nm or less. Specific examples include actinic rays such as KrF excimer laser (248 nm), ArF excimer laser (193 nm), and F ₂ excimer laser (157 nm), and radiation such as X-rays and electron beams.

Examples of the alkali developer for the positive resist composition include inorganic hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, and primary amines such as ethylamine and n-propylamine. Secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide Alkaline aqueous solutions of cyclic amines such as quaternary ammonium salts such as pyrrole and pihelidine can be used.
Furthermore, an appropriate amount of alcohol or surfactant may be added to the alkaline aqueous solution.
The alkali concentration of the alkali developer is usually from 0.1 to 20% by mass, and the pH is usually from 10.0 to 14.0.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

Synthesis Example 1 (Synthesis of Resin (1))
2-adamantyl-2-propyl methacrylate, dihydroxyadamantane methacrylate, norbornane lactone acrylate and succinic acid monoethylene glycol methacrylate were charged at a ratio of 30/20/40/10, and propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 60/40. 450 g of a solution having a solid content concentration of 22% by mass was prepared. 9 mol% of a polymerization initiator V-601 manufactured by Wako Pure Chemical Industries, Ltd. was added to this solution, and this was heated to 80 ° C. over 6 hours under a nitrogen atmosphere. It was dripped at 50 g of mixed solutions. The reaction liquid was stirred for 2 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 hexane / ethyl acetate = 9/1, and the precipitated white powder was collected by filtration to recover the target resin (1).
^The polymer composition ratio (molar ratio) determined from ¹³ CNMR was a / b / c / d = 31/20/39/10. Moreover, the standard polystyrene conversion weight average molecular weight calculated | required by GPC measurement was 8010, and dispersion degree was 2.1.
Resins (1) to (17) were synthesized according to Synthesis Example 1.

  Hereinafter, the structures of the resins (1) to (17) are shown.

  Table 1 below shows the composition ratio, molecular weight, and dispersity of the resins (1) to (17).

Synthesis Example 2 (Synthesis of Compound ((I) -1))
After adding 6.1 g (0.03 mol) of diphenyl sulfoxide to a tetrahydrofuran solution of Grignard reagent prepared by a conventional method from 31.3 g (0.075 mol) of 4-nonafluorobutylbromobenzene, 8.1 g of trimethylsilyl chloride ( 0.075 mol) was added dropwise at 0 to 30 ° C. and stirred for 3 hours. After completion of the reaction, the resulting reaction solution was poured into 100 ml of 12% hydrobromic acid, washed with 75 ml of toluene, and extracted three times with 75 ml of dichloromethane. The obtained target product was concentrated to dryness and crystallized by adding 100 ml of ethyl acetate to obtain 7.5 g of 4-nonafluorobutylphenyldiphenylsulfonium bromide.
5.6 g (0.01 mol) of 4-nonafluorobutylphenyl diphenylsulfonium bromide obtained was dissolved in 50 ml of methanol, 2.3 g (0.01 mol) of silver oxide was added, and the mixture was stirred at room temperature for 2 hours. The obtained silver salt was filtered, 3.0 g (0.01 mol) of nonafluorobutanesulfonic acid was added, and the mixture was stirred at room temperature for 1 hour. The obtained crude composition was concentrated to dryness, and 100 ml of normal hexane was added for crystallization to obtain 7.60 g of compound ((I) -1).
The other compound (I) was obtained by the same synthesis method as in Synthesis Example 2.

Examples 1-4 and Comparative Examples 1-3
(Preparation and evaluation of positive resist composition)
1.03 g of resin,
Photoacid generator 0.00035 mol,
Nitrogen-containing basic compound 1.65mg and surfactant 100ppm in total
Were dissolved in the solvent shown in Table 2 so that the solid content was 11% by mass, and then filtered through a 0.1 μm microfilter, and Examples 1-4 and Comparative Example 1 were used. -3 positive resist compositions were prepared.

In the table, as the nitrogen-containing basic compound,
N-1: 1,5-diazabicyclo [4.3.0] -5-nonene N-2: 1,8-diazabicyclo [5.4.0] -7-undecene N-3: 4-dimethylaminopyridine N -4: triphenylimidazole N-5: diisopropylaniline N-6: tributylamine N-7: trioctylamine

As surfactant,
W-1: MegaFuck F176 (Dainippon Ink Chemical Co., Ltd.) (Fluorine)
W-2: Megafuck R08 (Dainippon Ink Chemical Co., Ltd.) (fluorine and silicone)
Represents.

As a solvent,
S-1: Propylene glycol monomethyl ether acetate S-2: Ethyl lactate S-3: Butyl acetate S-4: 2-Heptanone S-5: Propylene glycol monomethyl ether S-6: Ethyl ethoxypropionate S-7: γ- Butyrolactone S-8: ethylene carbonate S-9: propylene carbonate S-10: represents cyclohexanone.

<Evaluation of sensitivity and resolution>
ARC29a manufactured by Brewer Science Co., Ltd. was uniformly applied to a silicon wafer subjected to hexamethyldisilazane treatment with a spin coater, dried at 100 ° C. for 90 seconds on a hot plate, and then heated at 205 ° C. for 60 seconds. And an antireflection film was formed. Then, each positive resist composition immediately after preparation was applied with a spin coater and heated at 120 ° C. for 90 seconds to form a 0.30 μm resist film.
The resist film was exposed with an ArF excimer laser stepper (NA = 0.6 manufactured by ISI) through a mask, and immediately after the exposure, it was heated on a hot plate at 120 ° C. for 90 seconds. Furthermore, it developed with 23.degree. C. for 60 seconds with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, rinsed with pure water for 30 seconds, and then dried to obtain a resist line pattern.
Sensitivity was expressed by an exposure amount (mJ / cm ² ) for reproducing a 0.15 μm line and space (1/1) pattern.
Further, the minimum dimension (μm) of the resist pattern that is resolved when the exposure is performed with this exposure amount is defined as the resolution.

<Profile evaluation>
The cross-sectional shape of the 0.15 μm line pattern obtained with the minimum exposure to reproduce the 0.15 μm line pattern on the mask was observed with a scanning electron microscope. A rectangular shape is indicated by ○, a round top shape is indicated by ×, and a slightly round top shape is indicated by Δ.

<Evaluation of initial particle value>
For each positive resist composition, the number of particles in the solution immediately after preparation was counted with a particle counter manufactured by Rion.

<Evaluation of curvature reproducibility>
The curvature radius of the bent portion of the obtained pattern (pattern size = 0.20 μm) at 90 degrees was obtained by observing from the upper surface of the wafer using a scanning electron microscope.

  The evaluation results are shown in Table 2.

  From Table 2, it is clear that the positive resist composition of the present invention has a high sensitivity, high resolution, rectangular profile, small initial particle value, and excellent curvature reproducibility.

Claims (4)

(A) a resin whose solubility in an alkaline developer is increased by the action of an acid;
(B-1) a triarylsulfonium salt having a fluorine atom in the cation moiety, which generates an aliphatic or aromatic sulfonic acid having a fluorine atom by irradiation with an actinic ray or radiation,
(B-2) a sulfonium salt that does not have a fluorine atom in the cation moiety, which generates an aliphatic or aromatic sulfonic acid having a fluorine atom by irradiation with actinic rays or radiation,
A positive resist composition comprising (C) a nitrogen-containing basic compound and (D) an organic solvent. As the organic solvent of component (D), it contains at least one selected from the following group A solvents, at least one selected from the group B solvents and / or at least one selected from the group C solvents. The positive resist composition according to claim 1, wherein:
Group A solvent: propylene glycol monoalkyl ether carboxylate Group B solvent: propylene glycol monoalkyl ether, alkyl lactate and alkyl alkoxypropionate Group C solvent: γ-butyrolactone, ethylene carbonate, propylene carbonate and cyclohexanone   The positive resist composition according to claim 1 or 2, wherein the resin (A) has a monocyclic or polycyclic alicyclic hydrocarbon structure.   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.