JP4617252B2 - Positive resist composition and pattern forming method using the same - Google Patents

Description

  The present invention relates to a positive resist composition suitably used in an ultramicrolithography process such as the manufacture of VLSI and high-capacity microchips and other photo-publishing processes, and a pattern forming method using the same. More specifically, the present invention relates to a positive resist composition capable of forming a highly refined pattern using electron beam, X-ray, EUV light, and the like, and a pattern forming method using the same. The present invention relates to a positive resist composition that can be suitably used for microfabrication of a semiconductor device using EUV light (wavelength: around 13 nm) and a pattern forming method using the same.

  Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a photoresist composition has been performed. In recent years, with the high integration of integrated circuits, the formation of ultrafine patterns in the submicron region and the quarter micron region has been required. Along with this, there is a tendency for the exposure wavelength to become shorter, such as g-line to i-line, KrF excimer laser light, and ArF excimer laser light. Furthermore, at present, in addition to excimer laser light, lithography using electron beams, X-rays, or EUV light is also being developed.

  In particular, electron beam lithography is positioned as a next-generation or next-generation pattern formation technique, and a positive resist with high sensitivity and high resolution is desired. In particular, high sensitivity is an extremely important issue for shortening the wafer processing time. However, in positive resists for electron beams, when trying to increase sensitivity, not only the resolution is lowered, but also the line edge. Roughness deteriorates, and development of a resist that satisfies these characteristics at the same time is strongly desired. Here, line edge roughness means that when the pattern is viewed from directly above because the edge of the resist pattern and the substrate interface irregularly fluctuate in the direction perpendicular to the line direction due to the characteristics of the resist. Say that the edge looks uneven. The unevenness is transferred by an etching process using a resist as a mask, and the electrical characteristics are deteriorated, so that the yield is lowered. Particularly in the ultrafine region of 0.25 μm or less, the line edge roughness is an extremely important improvement issue. High sensitivity, high resolution, good pattern shape, and good line edge roughness are in a trade-off relationship, and it is very important how to satisfy them simultaneously.

  Similarly, in lithography using KrF excimer laser light, X-rays or EUV light, it is also important to achieve both high sensitivity and high resolution, and these solutions are necessary.

  When EUV light is used as a light source, the wavelength of the light belongs to the extreme ultraviolet region and has high energy, and thus there is a problem such as a decrease in contrast due to the concerted photochemical reaction such as negation due to EUV light.

  In addition, when an electron beam, X-ray, EUV light source or the like is used, since exposure is performed under vacuum, a low boiling point compound such as a solvent or a resist material decomposed by high energy volatilizes and contaminates the exposure apparatus. The outgas problem is becoming important.

As a resist suitable for a lithography process using an electron beam, KrF excimer laser light, X-rays, or EUV light, a chemically amplified resist mainly utilizing an acid-catalyzed reaction is used from the viewpoint of high sensitivity. As a main component in a positive resist, a phenolic polymer (hereinafter abbreviated as a phenolic acid-decomposable resin) having a property that is insoluble or hardly soluble in an alkali developer and becomes soluble in an alkali developer by the action of an acid. And a chemically amplified resist composition comprising an acid generator is effectively used.

  Regarding positive resists for electron beams, KrF excimer laser light, X-rays, or EUV light, several resist compositions containing phenolic acid-decomposable resins have been known so far (for example, see Patent Documents 1 to 6). ).

  However, in any combination of these, at present, high sensitivity, high resolution, good pattern shape, good line edge roughness, and outgas reduction are not satisfied at the same time.

JP 2002-323768 A JP-A-6-41221 Japanese Patent No. 3173368 JP 2000-122291 A JP 2001-114825 A JP 2001-206917 A

  The object of the present invention is to solve the problem of performance improvement technology in microfabrication of a semiconductor device using KrF excimer laser light, electron beam, X-ray or EUV light, and has high sensitivity, high resolution, and good It is an object of the present invention to provide a positive resist composition that simultaneously satisfies an excellent pattern shape, good line edge roughness, and outgas reduction, and a pattern forming method using the same.

  As a result of intensive studies, the present inventors have found that the subject of the present invention is (A) a specific phenolic acid-decomposable resin, and (B) a specific compound that generates an acid upon irradiation with actinic rays or radiation. Has been found to be achieved by a positive resist composition containing

  That is, the present invention is achieved by the following configurations.

(1) (A) a resin having a repeating unit represented by the following general formula (I), which is insoluble or hardly soluble in an alkali developer and soluble in an alkali developer by the action of an acid; A positive resist composition comprising a compound having a sulfonium cation represented by the following general formula (II):

In general formula (I),
R ¹ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.
R ² represents a monovalent non-acid-decomposable group.
X represents a hydrogen atom or a monovalent organic group.
m represents an integer of 0 to 4.
When m is 2 to 4, a plurality of R ² may be the same or different.
In general formula (II),
R ^{3 to} R ¹⁵ each independently represent a hydrogen atom or a substituent, and those adjacent to each other may be bonded to each other to form a ring.
Z represents a single bond or a divalent linking group.

(2) The positive resist composition as described in (1), wherein X in the general formula (I) is represented by -C (R ¹⁶ ) (R ¹⁷ ) (OR ¹⁸ ).
However, R ¹⁶ and R ¹⁷ each independently represents a hydrogen atom or an alkyl group, and R ¹⁸ represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group.

  (3) The positive resist composition as described in (2), wherein the resin as the component (A) further has a repeating unit in which X in the general formula (I) is a hydrogen atom.

  (4) The positive resist composition as described in any one of (1) to (3), which is exposed by irradiation with EUV light.

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

  As a preferred embodiment of the present invention, the following configurations can be further exemplified.

  (6) The positive resist composition as described in any one of (1) to (4) above, wherein X in the general formula (I) has an alicyclic structure and / or an aromatic ring structure .

(7) The positive resist composition as described in any one of (2) to (4) above, wherein R ^{18 in} (2) has an alicyclic structure and / or an aromatic ring structure. .

  (8) The positive resist composition as described in any one of (1) to (4), (6) and (7) above, further comprising an organic basic compound.

  (9) The positive resist composition as described in any one of (1) to (4) and (6) to (8) above, which further contains a surfactant.

  (10) The positive resist according to any one of (1) to (4) and (6) to (9) above, wherein the counter anion of the compound of component (B) is an organic sulfonate anion Composition.

  (11) The positive resist composition as described in (10) above, further comprising a compound that generates a carboxylic acid by the action of actinic rays or radiation.

  (12) The positive resist composition as described in any one of (1) to (4) and (6) to (11) above, which further contains a solvent.

(13) The positive resist composition as described in (12) above, which contains propylene glycol monomethyl ether acetate as a solvent.

  (14) The positive resist composition as described in (13) above, further containing propylene glycol monomethyl ether as a solvent.

  (15) The positive resist composition as described in any one of (1) to (3) and (6) to (14) above, which is exposed by electron beam or X-ray irradiation.

  (16) A pattern forming method comprising: forming a resist film from the positive resist composition according to any one of (6) to (15) above; and exposing and developing the resist film.

  According to the present invention, it is possible to provide a positive resist composition that simultaneously satisfies high sensitivity, high resolution, good pattern shape, good line edge roughness, and outgas reduction, and a pattern forming method using the same.

  Hereinafter, the compounds used in 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 what does not have a substituent and what has a substituent. . For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

[1] (A) Resin having a repeating unit represented by the general formula (I), which is insoluble or hardly soluble in an alkali developer and becomes soluble in an alkali developer by the action of an acid. The type resist composition has a repeating unit represented by the following general formula (I), is insoluble or hardly soluble in an alkali developer, and has a property of being soluble in an alkali developer by the action of an acid (“( A) component resin ”.

In general formula (I),
R ¹ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.
R ² represents a monovalent non-acid-decomposable group.
X represents a hydrogen atom or a monovalent organic group.
m represents an integer of 0 to 4.
When m is 2 to 4, a plurality of R ² may be the same or different.

The resin of component (A) has a group (hereinafter also referred to as “acid-decomposable group”) that is insoluble or hardly soluble in an alkali developer and decomposes by the action of an acid and becomes soluble in an alkali developer.
Examples of the acid-decomposable group include a group in which a hydrogen atom of an alkali-soluble group such as a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, or a thiol group is protected with a group capable of leaving by the action of an acid. .
Examples of the group capable of leaving by the action of an acid (hereinafter also referred to as “acid leaving group”) include —C (R ¹⁶ ) (R ¹⁷ ) (OR ¹⁸ ), —C (R ¹⁹ ) (R ²⁰ ). ) (R ²¹ ), —CO—OC (R ¹⁹ ) (R ²⁰ ) (R ²¹ ), and the like.
R ¹⁶ and R ¹⁷ each independently represents a hydrogen atom or an alkyl group. R ¹⁸ represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R ^{19 to} R ²¹ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. Two of R ¹⁶ , R ¹⁷ and R ¹⁸ , or two of R ¹⁹ , R ²⁰ and R ²¹ may be bonded to form a ring.
The resin of component (A) may have an acid-decomposable group in the repeating unit represented by the general formula (I), or other repeating units other than the repeating unit represented by the general formula (I). You may have in the unit, for example, the repeating unit represented by general formula (III) mentioned later.

In the general formula (I), the alkyl group represented by R ¹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, n -Butyl group, isobutyl group, sec-butyl group, pentyl group, isopentyl group, neopentyl group, t-pentyl group and the like can be mentioned.
The alkyl group of R ¹ may be substituted with a fluorine atom, and the alkyl group substituted with a fluorine atom is preferably a perfluoromethyl group or a perfluoroethyl group.
R ¹ is preferably a hydrogen atom, a methyl group, or a perfluoromethyl group, and particularly preferably a hydrogen atom or a methyl group.

The non-acid-decomposable group for R ² is a group that is not an acid-decomposable group, that is, a group that does not decompose with an acid generated from an acid generator or the like upon exposure to produce an alkali-soluble group such as a hydroxyl group or a carboxy group. Means.
Examples of the non-acid-decomposable group as R ² include a halogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an acyl group, —OC (═O) Ra, —OC (═O) ORa, — C (= O) ORa, -C (= O) N (Rb) Ra, -N (Rb) C (= O) Ra, -N (Rb) C (= O) ORa, -N (Rb) SO 2 Ra, may be mentioned _{-SRa, -SO 2 Ra, -SO 3} Ra, a -SO ₂ N (Rb) Ra or the like. Ra represents an alkyl group, a cycloalkyl group, or an aryl group. Rb represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.
The alkyl group as R ² may have a substituent, for example, an alkyl group having 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an n-butyl group. , Sec-butyl group, hexyl group and octyl group can be preferably mentioned.
The cycloalkyl group as R ² may have a substituent, for example, a cycloalkyl group having 3 to 15 carbon atoms, specifically, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group. Can be preferably mentioned.
The alkoxy group as R ² may have a substituent, for example, an alkoxy group having 1 to 8 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group. Preferred examples include cyclohexyloxy group and the like.
The aryl group as R ² may have a substituent, for example, an aryl group having 6 to 15 carbon atoms, and specifically includes a phenyl group, a tolyl group, a naphthyl group, an anthryl group, and the like. Preferable examples can be given.
The acyl group as R ² may have a substituent, for example, an acyl group having 2 to 8 carbon atoms, specifically, formyl group, acetyl group, propanoyl group, butanoyl group, pivaloyl Preferred examples include groups and benzoyl groups.
The substituents that these groups may have include hydroxyl group, carboxyl group, halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), alkoxy group (methoxy group, ethoxy group, propoxy group, butoxy group) Etc.). As for the cyclic structure, examples of the substituent further include an alkyl group (preferably having 1 to 8 carbon atoms).
The alkyl group, cycloalkyl group or aryl group as Ra and Rb is the same as those exemplified as R ² .

  The monovalent organic group as X is preferably a group having 1 to 40 carbon atoms and not leaving an oxygen atom by the action of an acid (hereinafter also referred to as “non-acid leaving group”). It may be an acid leaving group capable of leaving from an oxygen atom by the action of an acid.

Non-acid leaving groups include, for example, alkyl groups (excluding tertiary alkyl groups), cycloalkyl groups, alkenyl groups, aryl groups, alkyloxy groups (provided that -O-tertiary alkyl groups are Ex.), Acyl group, cycloalkyloxy group, alkenyloxy group, aryloxy group, alkylamidooxy group, alkylcarbonyloxy group, alkylamidomethyloxy group, alkylamido group, arylamidomethyl group, arylamido group, etc. It is done.
The non-acid leaving group is preferably an alkyl group, an acyl group, an alkylcarbonyloxy group, an alkyloxy group, a cycloalkyloxy group, an aryloxy group, an alkylamidooxy group, or an alkylamido group, more preferably An alkyl group, an acyl group, an alkylcarbonyloxy group, an alkyloxy group, a cycloalkyloxy group, and an aryloxy group.
In the non-acid leaving group, the alkyl group is preferably an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, or a sec-butyl group. , A cyclopropyl group, a cyclobutyl group, a cyclohexyl group, and an adamantyl group having 3 to 10 carbon atoms are preferable, and the alkenyl group has a carbon number of 2 such as a vinyl group, a propenyl group, an allyl group, and a butenyl group. Four are preferable, and the aryl group is preferably one having 6 to 14 carbon atoms such as phenyl group, xylyl group, toluyl group, cumenyl group, naphthyl group, and anthracenyl group. The alkyloxy group is preferably an alkyloxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a hydroxyethoxy group, a propoxy group, a hydroxypropoxy group, an n-butoxy group, an isobutoxy group, or a sec-butoxy group.

Examples of the acid leaving group for X include —C (R ¹⁶ ) (R ¹⁷ ) (OR ¹⁸ ), —C (R ¹⁹ ) (R ²⁰ ) (R ²¹ ), —CO—OC (R ¹⁹ ). (R ²⁰ ) (R ²¹ ) and the like can be mentioned.
R ¹⁶ and R ¹⁷ each independently represents a hydrogen atom or an alkyl group. R ¹⁸ represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. R ^{19 to} R ²¹ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group. Two of R ¹⁶ , R ¹⁷ and R ¹⁸ , or two of R ¹⁹ , R ²⁰ and R ²¹ may be bonded to form a ring.
The alkyl group as R ¹⁶ and R ¹⁷ may have a substituent, for example, an alkyl group having 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, n Preferred examples include -butyl group, sec-butyl group, hexyl group and octyl group. More preferred are a methyl group and an ethyl group, and particularly preferred is a methyl group.
The alkyl group as R ¹⁸ may have a substituent and has 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, and a t-butyl group. The cycloalkyl group is preferably one having 3 to 10 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclohexyl group, adamantyl group, and the alkenyl group is vinyl group, propenyl group, allyl group. Group, butenyl group having 2 to 4 carbon atoms such as butenyl group is preferable, and aryl group has 6 to 14 carbon atoms such as phenyl group, xylyl group, toluyl group, cumenyl group, naphthyl group and anthracenyl group. Those are preferred.
The alkyl group, cycloalkyl group, alkenyl group, aralkyl group and aryl group in R ^{19 to} R ²¹ are the same as the alkyl group, cycloalkyl group, alkenyl group, aralkyl group and aryl group in R ¹⁸ . Things can be mentioned.

A group having an acid-decomposable group can be introduced into X in the general formula (I) by modification. Thus, X which introduce | transduced the acid-decomposable group is as follows, for example.
- ^{[C (R 24) (R 25} ) ] ^{p-CO-OC (R 19} ) (R 20) (R 21)
R ²⁴ and R ²⁵ each independently represents a hydrogen atom or an alkyl group. p is an integer of 1 to 4.

  m is preferably 0 or 1.

In the resin of component (A), the repeating unit represented by the general formula (I) is preferably a repeating unit in which X is a hydrogen atom or an acid leaving group, and X is —C (R ¹⁶ ). The repeating unit represented by (R ¹⁷ ) (OR ¹⁸ ) is more preferred.

The resin of component (A) is a repeating unit represented by the general formula (I), wherein X is -C (R ¹⁶ ) (R ¹⁷ ) (OR ¹⁸ ), In the repeating unit represented by (II), it is particularly preferable that X has a repeating unit which is a hydrogen atom.

  In the resin (A), in the repeating unit represented by the general formula (I), X preferably has an alicyclic structure and / or an aromatic ring structure.

In the resin of component (A), in the repeating unit represented by the general formula (I), X is —C (R ¹⁶ ) (R ¹⁷ ) (OR ¹⁸ ), and R ^{18 in} X Preferably has an alicyclic structure and / or an aromatic ring structure.

The resin of component (A) is an alkali-soluble group such as a phenolic hydroxyl group, a carboxyl group, a sulfonic acid group, a hexafluoroisopropanol group (—C (CF ₃ )) in order to maintain good developability for an alkali developer. ₂ OH) may be copolymerized with other suitable polymerizable monomers, and other hydrophobic polymerizable monomers such as alkyl acrylates and alkyl methacrylates may be copolymerized to improve film quality. May be.
The resin as component (A) may be copolymerized with a methacrylate or acrylate having a hydrophilic group such as alkyleneoxy or lactone for the purpose of adjusting hydrophilicity / hydrophobicity.
(A) Component resin is styrene (alkyl group, halogen atom, alkylthio group, sulfonyl group, ester group, acyloxy group may be substituted), vinyl naphthalene (alkyl group, halogen atom, alkylthio group, sulfonyl group). , Ester group and acyloxy group may be substituted), vinylanthracene (alkyl group, halogen atom, alkylthio group, sulfonyl group, ester group and acyloxy group may be substituted), acrylamides, methacrylamides Allyl compounds, vinyl ethers, vinyl esters and the like may be copolymerized.

  The resin of component (A) preferably has a repeating unit represented by the following general formula (III).

In general formula (III),
Ra represents a hydrogen atom, a methyl group, a halogen atom or a cyano group.
Rb represents an acid leaving group.

  The acid leaving group for Rb in the general formula (III) is the same as the acid leaving group in the general formulas (I) and X.

In the resin of component (A), the content of the repeating unit represented by the general formula (I) is preferably 3 to 100 mol%, more preferably 5 to 90 mol in all repeating units constituting the resin. %, Particularly preferably 10 to 85 mol%.
The content of the repeating unit having an alkali-soluble group such as a hydroxyl group, a carboxy group, or a sulfonic acid group is preferably 1 to 99 mol%, more preferably 3 to 95 mol%, particularly preferably in all repeating units constituting the resin. 5 to 90 mol%.
The content of the repeating unit having an acid-decomposable group is preferably 3 to 95 mol%, more preferably 5 to 90 mol%, and particularly preferably 10 to 85 mol% in all repeating units constituting the resin.

  The resin of component (A) can be decomposed with an acid into an alkali-soluble resin as described in European Patent No. 254853, Japanese Patent Laid-Open No. 2-258500, Japanese Patent Laid-Open No. 3-223860, and Japanese Patent Laid-Open No. 4-251259. It can be synthesized by a known synthesis method such as a method of reacting a precursor of a group or a method of copolymerizing a monomer having a group capable of decomposing with an acid with various monomers.

The weight average molecular weight (Mw) of the component (A) resin is preferably in the range of 1,000 to 200,000, more preferably in the range of 1,500 to 100,000, and particularly preferably It is in the range of 2,000 to 50,000. 1000 or more is preferable from the viewpoint of prevention of film loss in the unexposed area, and 200000 or less is preferable from the viewpoint of the dissolution rate and sensitivity of the resin itself in alkali. Moreover, it is preferable that molecular weight dispersion degree (Mw / Mn) is 1.0-4.0, More preferably, it is 1.0-3.0, Most preferably, it is 1.0-2.5.
Here, the weight average molecular weight is defined by a polystyrene conversion value of gel permeation chromatography.

  Two or more types of the resin (A) may be used in combination.

  The amount of the component (A) resin added is generally 30 to 99% by mass, preferably 40 to 97% by mass, particularly preferably 50 to 95% by mass, based on the solid content of the positive resist composition. %.

Hereinafter, specific examples of the resin having the repeating unit represented by the general formula (I), which is insoluble or hardly soluble in an alkali developer and becomes soluble in an alkali developer by the action of an acid will be shown. The invention is not limited to this.

[2] (B) Compound having sulfonium cation represented by general formula (II) The positive resist composition of the present invention comprises a compound having a sulfonium cation represented by the following general formula (II) ("(B) Component compounds ”).

In general formula (II),
R ^{3 to} R ¹⁵ each independently represent a hydrogen atom or a substituent, and those adjacent to each other may be bonded to each other to form a ring.
Z represents a single bond or a divalent linking group.

The substituents for R ^{3 to} R ^{15 in} the general formula (II) may be any substituent and are not particularly limited. For example, a halogen atom, an alkyl group, a cycloalkyl group (bicycloalkyl group, tricycloalkyl group) Group), alkenyl group (including cycloalkenyl group and bicycloalkenyl group), alkynyl group, aryl group, heterocyclic group (may be referred to as heterocyclic group), cyano group, hydroxyl group, nitro group, carboxyl group , Alkoxy groups (including cycloalkoxy groups), aryloxy groups, silyloxy groups, heterocyclic oxy groups, acyloxy groups, carbamoyloxy groups, alkoxycarbonyloxy groups (including cycloalkoxycarbonyloxy groups), aryloxycarbonyloxy groups, Amino group (including anilino group), ammonio group, acyla Group, aminocarbonylamino group, alkoxycarbonylamino group (including cycloalkoxycarbonylamino group), aryloxycarbonylamino group, sulfamoylamino group, alkyl, cycloalkyl or arylsulfonylamino group, mercapto group, alkylthio group ( Cycloalkylthio group), arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl, cycloalkyl or arylsulfinyl group, alkyl, cycloalkyl or arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group (Including cycloalkoxycarbonyl group), carbamoyl group, aryl or heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, Sufi arylsulfonylamino group, a phosphono group, a silyl group, a hydrazino group, ₍₂ -B (OH)) ureido group, a boronic acid group, a phosphato group (-OPO (OH) _2), a sulfato group (-OSO ₃ H), and other These known substituents are exemplified.
R ^{3 to} R ¹⁵ are preferably a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group (including a bicycloalkyl group or a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group or a bicycloalkenyl group), alkynyl Group, aryl group, cyano group, hydroxyl group, carboxyl group, alkoxy group (including cycloalkoxy group), aryloxy group, acyloxy group, carbamoyloxy group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group (cyclo Alkoxycarbonylamino group), aryloxycarbonylamino group, sulfamoylamino group, alkyl, cycloalkyl or arylsulfonylamino group, alkylthio group (including cycloalkylthio group), arylthio group, sulfamo Group, an alkyl, cycloalkyl or aryl-sulfonyl group, an aryloxycarbonyl group, (including cycloalkoxy group) alkoxycarbonyl group, a carbamoyl group, an imido group, a silyl group, a ureido group.
R ^{3 to} R ¹⁵ are more preferably a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group (including a bicycloalkyl group or a tricycloalkyl group), a cyano group, a hydroxyl group, or an alkoxy group (including a cycloalkoxy group). ), Acyloxy group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group (including cycloalkoxycarbonylamino group), alkyl, cycloalkyl or arylsulfonylamino group, alkylthio group (including cycloalkylthio group), sulfamoyl group, An alkyl, cycloalkyl or arylsulfonyl group, an alkoxycarbonyl group (including a cycloalkoxycarbonyl group), and a carbamoyl group;
As R ^{3 to} R ¹⁵ , hydrogen atoms, alkyl groups, cycloalkyl groups (including bicycloalkyl groups and tricycloalkyl groups), cyano groups, hydroxyl groups, alkoxy groups (including cycloalkoxy groups), alkyls are particularly preferable. A sulfonyl group.

Examples of the ring formed by bonding R ^{3 to} R ¹⁵ adjacent to each other include aromatic, non-aromatic hydrocarbon rings, heterocyclic rings, and polycyclic condensed rings obtained by further combining these, For example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, Pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenant Lysine ring, acridine ring, Ntororin ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring, and the like.

Examples of the divalent linking group for Z include an alkylene group, an arylene group, an ether group, a thioether group, an amino group, —CH═CH—, —C≡C—, and the like, and may have a substituent. . As these substituents, the same substituents as those shown for R ^{3 to} R ¹⁵ can be exemplified.

  Z is preferably a single bond, an alkylene group (preferably a methylene group), an ether group or a thioether group, and more preferably a single bond, an ether group or a thioether group.

The compound of component (B) has a counter anion. The counter anion is preferably an organic anion. An organic anion is an anion having at least one carbon atom. Furthermore, the organic anion is preferably a non-nucleophilic anion. A non-nucleophilic anion is an anion that has an extremely low ability to cause a nucleophilic reaction, and is an anion that can suppress degradation over time due to an intramolecular nucleophilic reaction.
Examples of the non-nucleophilic anion include a sulfonate anion, a carboxylate anion, a sulfonylimide anion, a bis (alkylsulfonyl) imide anion, and a tris (alkylsulfonyl) methyl anion.
Examples of the non-nucleophilic sulfonate anion include an aliphatic sulfonate anion, an aromatic sulfonate anion, a camphor sulfonate anion, and the like. Examples of the non-nucleophilic carboxylate anion include an aliphatic carboxylate anion, an aromatic carboxylate anion, and an aralkylcarboxylate anion.
The aliphatic moiety in the aliphatic sulfonate anion may be an alkyl group or a cycloalkyl group, preferably an alkyl group having 1 to 30 carbon atoms and a cycloalkyl group having 3 to 30 carbon atoms, for example, Methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl Group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group, boronyl group, etc. .
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.
Examples of the substituent of the alkyl group, cycloalkyl group and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion include, for example, a nitro group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), carboxyl Group, hydroxyl group, amino group, cyano group, alkoxy group (preferably 1 to 5 carbon atoms), cycloalkyl group (preferably 3 to 15 carbon atoms), aryl group (preferably 6 to 14 carbon atoms), alkoxycarbonyl group (Preferably having 2 to 7 carbon atoms), acyl group (preferably having 2 to 12 carbon atoms), alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms) and the like can be mentioned. 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 moiety in the aliphatic carboxylate anion include the same alkyl group and cycloalkyl group as in the aliphatic sulfonate anion.
Examples of the aromatic group in the aromatic carboxylate anion include the same aryl 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.
Examples of the substituent of the alkyl group, cycloalkyl group, aryl group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion include, for example, the same halogen as in the aromatic sulfonate anion. Atoms, alkyl groups, cycloalkyl groups, alkoxy groups, alkylthio groups and the like can be mentioned.
Examples of the sulfonylimide anion include saccharin anion.
The alkyl group in the bis (alkylsulfonyl) imide anion and tris (alkylsulfonyl) methyl anion is preferably an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, An isobutyl group, a sec-butyl group, a pentyl group, a neopentyl group, and the like can be given. Examples of the substituent for these alkyl groups include a halogen atom, an alkyl group substituted with a halogen atom, an alkoxy group, and an alkylthio group.
Examples of other non-nucleophilic anions include fluorinated phosphorus, fluorinated boron, and fluorinated antimony.

  The counter anion of the component (B) compound is preferably a sulfonate anion, and more preferably an aromatic sulfonate anion.

  Specific examples of counter anions include methane sulfonate anion, trifluoromethane sulfonate anion, pentafluoroethane sulfonate anion, heptafluoropropane sulfonate anion, perfluorobutane sulfonate anion, perfluorohexane sulfonate anion, perfluoro. Octane sulfonate anion, pentafluorobenzene sulfonate anion, 3,5-bistrifluoromethylbenzene sulfonate anion, 2,4,6-triisopropylbenzene sulfonate anion, perfluoroethoxyethane sulfonate anion, 2, 3, 5 , 6-tetrafluoro-4-dodecyloxybenzenesulfonate anion, p-toluenesulfonate anion, pentafluorobenzenesulfonate anion, camphorsulfonate anion and the like.

  The counter anion that the compound of the component (B) has with the sulfonium cation represented by the general formula (I) may be monovalent or divalent. When the counter anion is divalent or higher, the compound of the component (B) can have two or more sulfonium cations represented by the general formula (I).

  The compound of component (B) is obtained by oxidizing a cyclic sulfide compound with hydrogen peroxide to form a sulfoxide compound, and reacting the obtained sulfoxide compound with a target aromatic compound in the presence of an acid catalyst to form a triphenylsulfonium salt structure. Can be synthesized by salt exchange with the desired anion.

  The content of the component (B) compound is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 7%, based on the total solid content of the positive resist composition. % By mass.

  The compound (B) is an acid generator that generates an acid upon irradiation with actinic rays or radiation.

  The compound of the component (B) can be synthesized by a known method described in JP 2003-149800 A.

  Hereinafter, although the specific example of the compound which has a sulfonium cation represented by general formula (II) is given, this invention is not limited to this.

(Combination acid generator)
In the present invention, in addition to the compound of component (B), a compound that decomposes by irradiation with actinic rays or radiation to generate an acid (a combined acid generator) may be used in combination.

  The amount of the combined acid generator used is usually 100/0 to 20/80, preferably 100/0 to 40/60, and more preferably 100 / in molar ratio (compound of component (B) / combined acid generator). 0-50 / 50.

  Examples of such a combined acid generator include a photoinitiator for photocationic polymerization, a photoinitiator for photoradical polymerization, a photodecolorant for dyes, a photochromic agent, or an actinic ray used in a microresist or the like Known compounds that generate an acid upon irradiation with radiation and mixtures thereof can be appropriately selected and used.

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

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

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

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

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

Examples of the non-nucleophilic anion as Z ⁻ 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.

  The aliphatic moiety in the aliphatic sulfonate anion may be an alkyl group or a cycloalkyl group, preferably an alkyl group having 1 to 30 carbon atoms and a cycloalkyl group having 3 to 30 carbon atoms. For example, 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, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group, boronyl group, etc. be able to.

  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.

Examples of the substituent of the alkyl group, cycloalkyl group and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion include, for example, a nitro group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), carboxyl Group, hydroxyl group, amino group, cyano group, alkoxy group (preferably having 1 to 5 carbon atoms), cycloalkyl group (preferably having 3 to 15 carbon atoms), aryl group (preferably having 6 to 14 carbon atoms), alkoxycarbonyl group (Preferably having 2 to 7 carbon atoms), acyl group (preferably having 2 to 12 carbon atoms), alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms) and the like can be mentioned. 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 moiety in the aliphatic carboxylate anion include the same alkyl group and cycloalkyl group as in the aliphatic sulfonate anion.

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

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

  Examples of the substituent of the alkyl group, cycloalkyl group, aryl group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion include, for example, an aromatic sulfonate anion. The same halogen atom, alkyl group, cycloalkyl group, alkoxy group, alkylthio group and the like can be mentioned.

  Examples of the sulfonylimide anion include saccharin anion.

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

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

Examples of the non-nucleophilic anion of Z ⁻ 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 perfluoroalkanesulfonic acid anion having 4 to 8 carbon atoms, a benzenesulfonic acid anion having a fluorine atom, most preferably nonafluorobutanesulfonic acid anion, perfluorooctanesulfonic acid anion, penta Fluorobenzenesulfonate anion, 3,5-bis (trifluoromethyl) benzenesulfonate anion.

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.

  More preferable (ZI) components include compounds (ZI-1), (ZI-2), and (ZI-3) described below.

The compound (ZI-1) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (ZI), arylsulfonium compounds, namely, compounds containing an 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 with the remaining being an alkyl group or a cycloalkyl group.

  Examples of the arylsulfonium compound include triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, and aryldicycloalkylsulfonium compounds.

  Examples of the aryl group of the arylsulfonium compound include an aryl group composed of a hydrocarbon and a heteroaryl group having a hetero atom such as a nitrogen atom, a sulfur atom, or an oxygen atom. The aryl group composed of hydrocarbon is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. Examples of the heteroaryl group include a pyrrole group, an indole group, a carbazole group, a furan group, and a thiophene group, and an indole group is preferable. 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 or cycloalkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms and a cycloalkyl group having 3 to 15 carbon atoms, such as a methyl group, Examples thereof include an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.

Aryl group, alkyl group of R ₂₀₁ to R _203, cycloalkyl group, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 14 carbon atoms) , An alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, or a phenylthio group may be substituted. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and linear, branched or cyclic alkoxy groups having 1 to 12 carbon atoms, most preferably carbon. These are an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (ZI-2) will be described.
Compound (ZI-2) is a compound in the case where R _{201 to} R ₂₀₃ in formula (ZI) each independently represents an organic group containing no 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 preferably each independently an alkyl group, a cycloalkyl group, an allyl group,
A vinyl group, more preferably a linear or branched 2-oxoalkyl group, a 2-oxocycloalkyl group, or an alkoxycarbonylmethyl group, and particularly preferably a linear or branched 2-oxoalkyl group.

The alkyl group and cycloalkyl group of R ₂₀₁ to R _203, preferably a linear or branched alkyl group having 1 to 10 carbon atoms (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group), carbon Examples thereof include cycloalkyl groups of several 3 to 10 (cyclopentyl group, cyclohexyl group, norbornyl group). More preferred examples of the alkyl group include a 2-oxoalkyl group and an alkoxycarbonylmethyl group. More preferred examples of the cycloalkyl group include a 2-oxocycloalkyl group.

The 2-oxoalkyl group may be either linear or branched, and a group having> C = O at the 2-position of the above alkyl group is preferable.
The 2-oxocycloalkyl group is preferably a group having> C═O at the 2-position of the 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 (for example, 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 include a butylene group and a pentylene group.

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

The alkyl group as R _{1c to} R _7c may be either linear or branched, for example, an alkyl group having 1 to 20 carbon atoms, preferably a linear or branched alkyl group having 1 to 12 carbon atoms ( Examples thereof include a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, and a linear or branched pentyl group. The cycloalkyl group is, for example, a cyclic group having 3 to 8 carbon atoms. An alkyl group (for example, a cyclopentyl group, a cyclohexyl group) can be mentioned.

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 to 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 group and cycloalkyl group as in 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 in R _{1c to} R _5c .

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

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

Examples of the aryl group of R _{204 to} R ₂₀₇ include an aryl group composed of a hydrocarbon and a heteroaryl group having a hetero atom such as a nitrogen atom, a sulfur atom, or an oxygen atom. The aryl group composed of hydrocarbon is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. Examples of the heteroaryl group include a pyrrole group, an indole group, a carbazole group, a furan group, and a thiophene group, and an indole group is preferable.

The alkyl group and cycloalkyl group in R ₂₀₄ to R _207, preferably a linear or branched alkyl group having 1 to 10 carbon atoms (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group), carbon Examples thereof include cycloalkyl groups of several 3 to 10 (cyclopentyl group, cyclohexyl group, norbornyl group).

Examples of the substituent that R _{204 to} R ₂₀₇ may have include an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), and an aryl group (for example, 6 carbon atoms).
To 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups, and the like.

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

  Examples of the combined acid generator may further include compounds represented by the following general formulas (ZIV), (ZV), and (ZVI).

In general formulas (ZIV) to (ZVI),
Ar ₃ and Ar ₄ each independently represents an aryl group.
R ₂₀₆ , R ₂₀₇ and R ₂₀₈ each independently represents an alkyl group, a cycloalkyl group or an aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

Of the combined acid generators, compounds represented by the general formulas (ZI) to (ZIII) are more preferable.
Further, as the combined acid generator, a compound that generates a sulfonic acid having one sulfonic acid group is preferable, and a compound that generates a monovalent perfluoroalkanesulfonic acid, or a fluorine atom or a group having a fluorine atom is more preferable. A compound that generates a substituted aromatic sulfonic acid, and particularly preferably a sulfonium salt of monovalent perfluoroalkanesulfonic acid.

  When the compound (B) and the combined acid generator are used, a compound whose counter anion is an organic sulfonate anion is used as the compound (B), and an actinic ray is used as the combined acid generator. Alternatively, it is preferable to use a compound that generates a carboxylic acid by the action of radiation.

  Among the combined acid generators, particularly preferred examples are given below.

[3] (C) Organic basic compound The positive resist composition of the present invention preferably contains an organic basic compound.
The organic basic compound contained in the positive resist composition of the present invention is preferably a compound having a stronger basicity than phenol. The molecular weight of the organic basic compound is usually 100 to 900, preferably 150 to 800, more preferably 200 to 700. Further, nitrogen-containing basic compounds are particularly preferable.

  Preferred nitrogen-containing basic compounds are compounds having structures of the following general formulas (A) to (E) as a preferred chemical environment. The general formulas (B) to (E) may be part of a ring structure.

In the general formulas (A) to (E),
R ²⁵⁰ , R ²⁵¹ and R ²⁵² may be the same or different and are a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. Where R ²⁵¹ and R ²⁵² may combine with each other to form a ring.
The alkyl group and cycloalkyl group may be unsubstituted or have a substituent. Examples of the alkyl group and cycloalkyl group having a substituent include an aminoalkyl group having 1 to 20 carbon atoms, A hydroxyalkyl group having 1 to 20 carbon atoms, an aminocycloalkyl group having 3 to 20 carbon atoms, and a hydroxycycloalkyl group having 3 to 20 carbon atoms are preferable.
R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R ²⁵⁶ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms.

  Further preferred compounds are nitrogen-containing basic compounds having two or more nitrogen atoms of different chemical environments in one molecule, and particularly preferably both a substituted or unsubstituted amino group and a ring structure containing a nitrogen atom. Or a compound having an alkylamino group.

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

  Particularly preferred compounds include guanidine, 1,1-dimethylguanidine, 1,1,3,3-tetramethylguanidine, imidazole, 2-methylimidazole, 4-methylimidazole, N-methylimidazole, 2-phenylimidazole, 4 , 5-diphenylimidazole, 2,4,5-triphenylimidazole, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2-dimethylaminopyridine, 4-dimethylaminopyridine, 2-diethylaminopyridine, 2- (Aminomethyl) pyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-6-methylpyridine, 3-aminoethylpyridine, 4- Aminoethylpyridine, 3-aminopyrrolidine, Perazine, N- (2-aminoethyl) piperazine, N- (2-aminoethyl) piperidine, 4-amino-2,2,6,6-tetramethylpiperidine, 4-piperidinopiperidine, 2-iminopiperidine, 1- (2-aminoethyl) pyrrolidine, pyrazole, 3-amino-5-methylpyrazole, 5-amino-3-methyl-1-p-tolylpyrazole, pyrazine, 2- (aminomethyl) -5-methylpyrazine, Examples include, but are not limited to, pyrimidine, 2,4-diaminopyrimidine, 4,6-dihydroxypyrimidine, 2-pyrazoline, 3-pyrazoline, N-aminomorpholine, N- (2-aminoethyl) morpholine. It is not a thing.

  A tetraalkylammonium salt type nitrogen-containing basic compound can also be used. Of these, tetraalkylammonium hydroxide having 1 to 8 carbon atoms (tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra- (n-butyl) ammonium hydroxide, etc.) is particularly preferable. These nitrogen-containing basic compounds are used alone or in combination of two or more.

  The use ratio of the acid generator and the organic basic compound in the composition is preferably acid generator / organic basic compound (molar ratio) = 2.5 to 300. In other words, the molar ratio is preferably 2.5 or more from the viewpoint of sensitivity and resolution, and is preferably 300 or less from the viewpoint of suppressing the reduction in resolution due to the thickening of the resist pattern over time until post-exposure heat treatment. The acid generator / organic basic compound (molar ratio) is more preferably 5.0 to 200, still more preferably 7.0 to 150.

[4] (D) Surfactant In the present invention, surfactants can be used, which are preferable from the viewpoints of film forming properties, pattern adhesion, development defect reduction, and the like.

  Specific examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene Polyoxyethylene alkyl allyl ethers such as nonylphenol ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Sorbitan fatty acid esters such as rate, polyoxyethylene sorbitan monolaurate, polyoxyethylene Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as bitane monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, Ftop EF301, EF303, EF352 (manufactured by Shin-Akita Kasei Co., Ltd.), MegaFuck F171, F173 (manufactured by Dainippon Ink and Chemicals), Florad FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), Troysol S-366 (manufactured by Troy Chemical Co., Ltd.), etc. Hexane polymer KP341 (manufactured by Shin-Etsu Chemical Co.) and acrylic or methacrylic acid-based (co) polymer Polyflow No. 75, no. 95 (manufactured by Kyoeisha Yushi Chemical Co., Ltd.).

  As the surfactant, any one of fluorine-based and / or silicon-based surfactants (fluorine-based surfactant and silicon-based surfactant, surfactant containing both fluorine atom and silicon atom), or two kinds of surfactants It is preferable to contain the above.

  Examples of the fluorine-based and / or silicon-based surfactant 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.

  Commercially available fluorine-based and / or silicon-based surfactants include, for example, F-top EF301, EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430, 431 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173 , F176, F189, R08 (Dainippon Ink Chemical Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troisol S-366 (Troy Chemical ( Fluorine-based surfactants or silicon-based surfactants such as those manufactured by the same company). Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

As the fluorine-based and / or silicon-based surfactants, in addition to the known ones as described above, fluoro produced by a telomerization method (also referred to as a telomer method) or an oligomerization method (also referred to as an oligomer method). A surfactant using a polymer having a fluoroaliphatic group derived from an aliphatic compound can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.

  As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. Or may be block copolymerized. Examples of the poly (oxyalkylene) group include a poly (oxyethylene) group, a poly (oxypropylene) group, a poly (oxybutylene) group, and the like, and a poly (oxyethylene, oxypropylene, and oxyethylene group). A unit having different chain lengths in the same chain length, such as a block linked body) or a poly (block linked body of oxyethylene and oxypropylene) group, may be used. Furthermore, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate (or methacrylate) is not only a binary copolymer but also a monomer having two or more different fluoroaliphatic groups, Further, it may be a ternary or higher copolymer obtained by simultaneously copolymerizing two or more different (poly (oxyalkylene)) acrylates (or methacrylates).

Examples of commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (Dainippon Ink Chemical Co., Ltd.). Further, a copolymer of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxyalkylene)) acrylate (or methacrylate), an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxy) (Ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate) copolymer, acrylate (or methacrylate) and (poly (oxyalkylene)) acrylate having C ₈ F ₁₇ groups (or Copolymer of acrylate (or methacrylate), (poly (oxyethylene)) acrylate (or methacrylate), and (poly (oxypropylene)) acrylate (or methacrylate) having a C ₈ F ₁₇ group Coalesce, etc. Can.

  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).

[5] Other components The positive resist composition of the present invention may further contain a dye, a photobase generator and the like, if necessary.

1. Dye A dye can be used in the present invention.
Suitable dyes include oily dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (oriental chemical industry) Co., Ltd.), crystal violet (CI42555), methyl violet (CI42535), rhodamine B (CI45170B), malachite green (CI42000), methylene blue (CI522015) and the like.

2. Photobase generator As the photobase generator that can be added to the composition of the present invention, JP-A-4-151156, 4
-162040, 5-197148, 5-5995, 6-194434, 8-146608, 10-83079, and European Patent 622682, specifically, , 2-nitrobenzyl carbamate, 2,5-dinitrobenzyl cyclohexyl carbamate, N-cyclohexyl-4-methylphenylsulfonamide, 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate, and the like can be suitably used. . These photobase generators are added for the purpose of improving the resist shape and the like.

3. Solvents The positive resist composition of the present invention is dissolved in a solvent that dissolves each of the above components and coated on a support. The solid content concentration of all resist components is usually preferably 2 to 30% by mass, more preferably 3 to 25% by mass.
Solvents used here include ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl ether acetate , Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, N, N-dimethyl Formamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran and the like are preferable. Or mixed to use.
The positive resist composition of the present invention preferably contains propylene glycol monomethyl ether acetate as a solvent.
The positive resist composition of the present invention preferably contains propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether as solvents.

  The resist composition of the present invention is applied onto a substrate to form a thin film. The thickness of the resist film is preferably 0.05 to 4.0 μm.

  In the present invention, a commercially available inorganic or organic antireflection film can be used if necessary. Furthermore, an antireflection film can be applied to the resist lower layer and used.

  As the antireflection film used as the lower layer of the resist, either an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, amorphous silicon, or an organic film type made of a light absorber and a polymer material may be used. it can. The former requires equipment such as a vacuum deposition apparatus, a CVD apparatus, and a sputtering apparatus for film formation. Examples of the organic antireflection film include a condensate of a diphenylamine derivative and a formaldehyde-modified melamine resin described in JP-B-7-69611, an alkali-soluble resin, a light absorber, and maleic anhydride copolymer described in US Pat. No. 5,294,680. A reaction product of a coalescence and a diamine type light absorbing agent, a resin binder described in JP-A-6-186863 and a methylolmelamine thermal crosslinking agent, a carboxylic acid group, an epoxy group and a light-absorbing group described in JP-A-6-118656. An acrylic resin-type antireflection film in the same molecule, a composition comprising methylol melamine and a benzophenone-based light absorber described in JP-A-8-87115, and a low-molecular light absorber added to a polyvinyl alcohol resin described in JP-A-8-179509 And the like.

  In addition, as the organic antireflection film, commercially available organic antireflection films such as DUV30 series, DUV-40 series manufactured by Brewer Science, AR-2, AR-3, AR-5 manufactured by Shipley, etc. may be used. it can.

  In the manufacture of precision integrated circuit elements, the pattern forming process on the resist film is carried out on the substrate (eg, silicon / silicon dioxide coated substrate, glass substrate, ITO substrate, quartz / chromium oxide coated substrate, etc.). A resist pattern is applied and dried to form a resist film, followed by irradiation with X-rays, electron beams, ion beams or EUV, preferably by heating, developing, rinsing and drying to form a good resist pattern can do.

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

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

Synthesis Example 1 (Synthesis of Resin (A1))
30 g of a metahydroxystyrene polymer (MHS8000, weight average molecular weight 8000, molecular weight dispersity 1.11) is dissolved in 100 g of propylene glycol monomethyl ether acetate (PGMEA), and the solution is decompressed to 60 ° C. and 20 mmHg, and about 20 g of solvent is dissolved. Distilled off with water remaining in the system. The mixture was cooled to 20 ° C., 7.88 g of 2-phenoxyethyl vinyl ether and 1.0 g of p-toluenesulfonic acid were added, and the mixture was stirred at room temperature for 1 hour. Thereafter, 1.16 g of triethylamine was added for neutralization, and 40 g of ethyl acetate and 40 g of water were added for washing operation three times. Thereafter, the amount of the solvent was adjusted to obtain a 30% by mass polymer solution. The weight average molecular weight of this polymer by GPC was 8500, the molecular weight dispersity was 1.12. From 1H and 13C-NMR analysis, the acetal protection rate of phenolic OH was 22%.

In the same manner as in Synthesis Example 1, the resins (A2), (A8), (A13) and (A16) as the component (A) were synthesized.
Table 1 below shows the weight average molecular weight, molecular weight dispersity, and composition ratio (molar ratio, corresponding to each repeating unit from the left) of the resins (A1), (A2), (A8), (A13), and (A16). .

Synthesis Example 2 (Synthesis of Compound (B2) 50 ml of toluene was added to 30 g of diphosphorus pentoxide / methanesulfonic acid = 10/1 solution, and dibenzothiophene-S-oxide (10 g) was added under ice cooling. After the reaction, the solution was added to ice water, the solution was filtered, and 23 g of potassium iodide was added to the mother liquor, and the precipitated crystals were collected by filtration. The precipitated crystals were filtered, 14.2 g of triisopropylbenzenesulfonic acid was added to the mother liquor, the solution was distilled off under reduced pressure, and the resulting crystals were recrystallized with a mixed solvent of ethyl acetate and ether to give a compound. 7.2 g of (B2) was obtained.

  In the same manner as in Synthesis Example 2, other component (B) compounds were synthesized.

Examples 1-7 and Comparative Examples 1-2
(Preparation of resist composition)
Shown in Table 2 below,
(A) Component resin: 0.948 g (in terms of solid content)
Compound of component (B): 0.05 g
If necessary, combined acid generator: 0.02 g
Basic compound: 0.003 g
Surfactant: 0.002g
Were dissolved in the solvent shown in Table 2 below to prepare a solution having a solid content concentration of 5.0% by mass. This solution was filtered through a 0.1 μm polytetrafluoroethylene filter to obtain a positive resist solution.

[Pattern formation and evaluation (EB)]
Using a spin coater, the prepared positive resist solution is uniformly coated on a hexamethyldisilazane-treated silicon wafer, and heated and dried at 120 ° C. for 90 seconds to form a positive resist film having a thickness of 0.3 μm. Formed. The resist film was irradiated with an electron beam using an electron beam drawing apparatus (HL750 manufactured by Hitachi, Ltd., acceleration voltage 50 KeV). After irradiation, it was baked at 110 ° C. for 90 seconds, immersed in an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 60 seconds, rinsed with water for 30 seconds and dried. The obtained pattern was evaluated by the following method.

〔sensitivity〕
The cross-sectional shape of the obtained pattern was observed using a scanning electron microscope (S-4300, manufactured by Hitachi, Ltd.). The minimum irradiation energy when resolving a 150 nm line (line: space = 1: 1) was defined as sensitivity.

[Resolution]
The resolving power was defined as the limiting resolving power (line and space were separated and resolving) at the irradiation dose showing the above sensitivity.

[Line edge roughness]
With respect to an arbitrary 30 points in the length direction 50 μm of the 150 nm line pattern at the irradiation amount showing the sensitivity, from the reference line where there should be an edge by using a scanning electron microscope (S-9220, manufactured by Hitachi, Ltd.) The distance was measured, the standard deviation was obtained, and 3σ was calculated.

[Pattern shape]
A cross section of a part having a line width of 150 nm (line / space = 1: 1) was observed with an SEM (S-8840, manufactured by Hitachi, Ltd.) and evaluated according to the following criteria.
A: When the angle between the pattern side wall and the substrate is 90 ± 2 degrees and the angle between the pattern side wall and the pattern surface is 90 ± 2 degrees B: The angle between the pattern side wall and the substrate is 85 degrees or more and less than 88 degrees Alternatively, when the angle between the pattern side wall and the pattern surface is not less than 92 degrees and less than 95 degrees, and the angle between the pattern side wall and the pattern surface is not less than 85 degrees and less than 88 degrees, or not less than 92 degrees and less than 95 degrees. When it is 95 degrees or more, when T-top shape is seen, or when the entire pattern surface is rounded

[Outgas]
Evaluation was performed based on the fluctuation rate of the film thickness when the minimum irradiation energy was applied when resolving the 150 nm line (line: space = 1: 1).
Outgas: ((film thickness before exposure) − (film thickness after exposure)) / (film thickness before exposure) × 100

  The results are shown in Table 2.

  Hereinafter, abbreviations in the table are shown.

  [Comparative resin / Comparative acid generator]

[Surfactant]
D-1: MegaFuck F176 (Dainippon Ink Chemical Co., Ltd.)
D-2: Megafuck R08 (manufactured by Dainippon Ink & Chemicals, Inc.)
D-3: Troisol S-366 (manufactured by Troy Chemical Co., Ltd.)
D-4: Polyoxyethylene lauryl ether [solvent]
S1: Propylene glycol monomethyl ether acetate S2: Propylene glycol monomethyl ether [basic compound]
N-1: Trioctylamine N-2: 1,5-diazabicyclo [4.3.0] -5-nonene N-3: 2,4,6-triphenylimidazole

  From the results of Table 2, the resist composition of the present invention relates to pattern formation by electron beam irradiation, and has higher sensitivity and higher resolution than the composition of the comparative example, excellent line edge roughness and pattern shape, and outgas. It can be seen that there are few.

[Pattern formation and evaluation (KrF)]
The prepared positive resist solution is uniformly applied on a silicon substrate subjected to hexamethyldisilazane treatment using a spin coater, and is heated and dried on a hot plate at 120 ° C. for 90 seconds to obtain a 0.4 μm resist. A film was formed.
The resist film was subjected to pattern exposure using a line and space mask using a KrF excimer laser stepper (NA = 0.63), and heated on a hot plate at 110 ° C. for 90 seconds immediately after the exposure. Further, development was performed 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 form a line pattern. These were subjected to the same sensitivity and resolution as described above. The line edge roughness, pattern shape, and outgas were evaluated.
The evaluation results are shown in Table 3 below.

  From the results in Table 3, the resist composition of the present invention relates to pattern formation by irradiation with KrF excimer laser light, and has higher sensitivity and higher resolution than the composition of the comparative example, and excellent line edge roughness and pattern shape. It turns out that there is also little outgas.

[Pattern formation and evaluation (EUV)]
Using a spin coater, the prepared positive resist solution is uniformly coated on a hexamethyldisilazane-treated silicon wafer, and heated and dried at 120 ° C. for 90 seconds to form a positive resist film having a thickness of 0.15 μm. Formed. The obtained resist film was subjected to surface exposure using EUV light (wavelength 13 nm) while changing the exposure amount by 0.5 mJ in the range of 0 to 10.0 mJ, and further baked at 110 ° C. for 90 seconds. Then, using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution, the dissolution rate at each exposure amount was measured to obtain a sensitivity curve. In this sensitivity curve, the exposure amount when the dissolution rate of the resist is saturated was taken as sensitivity, and the dissolution contrast (γ value) was calculated from the gradient of the linear portion of the sensitivity curve. The larger the γ value, the better the dissolution contrast.
Further, the outgas was evaluated in the same manner as in Example 1 for the formed resist film.
These results are shown in Table 4 below.

  From the results of Table 4, the resist composition of the present invention is superior in the property evaluation by irradiation with EUV light, with higher sensitivity, higher contrast and reduced outgas compared to the composition of the comparative example. I understand.

Claims (5)

(A) a resin having a repeating unit represented by the following general formula (I), insoluble or hardly soluble in an alkali developer, and soluble in an alkali developer by the action of an acid; and (B) the following general A positive resist composition comprising a compound having a sulfonium cation represented by the formula (II).

In general formula (I),
R ¹ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.
R ² represents a monovalent non-acid-decomposable group.
X represents a hydrogen atom or a monovalent organic group.
m represents an integer of 0 to 4.
When m is 2 to 4, a plurality of R ² may be the same or different.
In general formula (II),
R ^{3 to} R ¹⁵ each independently represent a hydrogen atom or a substituent, and adjacent ones may be bonded to each other to form a ring.
Z represents a single bond or a divalent linking group. 2. The positive resist composition according to claim 1, wherein X in the general formula (I) is represented by —C (R ¹⁶ ) (R ¹⁷ ) (OR ¹⁸ ).
However, R ¹⁶ and R ¹⁷ each independently represents a hydrogen atom or an alkyl group, and R ¹⁸ represents an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group or an aryl group.   The positive resist composition according to claim 2, wherein the resin of component (A) further has a repeating unit in which X in the general formula (I) is a hydrogen atom.   The positive resist composition according to claim 1, which is exposed by irradiation with EUV light.   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.