WO2013154210A1

WO2013154210A1 - Pattern forming method, actinic ray-sensitive or radiation-sensitive resin composition, resist film, electronic device manufacturing method using the same, and electronic device

Info

Publication number: WO2013154210A1
Application number: PCT/JP2013/061433
Authority: WO
Inventors: Shuhei Yamaguchi; Hidenori Takahashi; Kousuke Koshijima
Original assignee: Fujifilm Corporation
Priority date: 2012-04-11
Filing date: 2013-04-11
Publication date: 2013-10-17
Also published as: JP2013218223A

Abstract

There is provided a pattern forming method comprising: (i) a step of forming a film by using an actinic ray-sensitive or radiation-sensitive resin composition containing (A) a resin having a weight average molecular weight of 7,000 or more and having (I) a structure containing a group having basicity or capable of decomposing by an action of an acid to increase basicity and (II) a structure being different from the structure (I) and containing a group capable of decomposing by the action of an acid to produce a polar group, and (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation; (ii) a step of exposing the film; and (iii) a step of developing the exposed film by using an organic solvent-containing developer to form a negative pattern.

Description

DESCRIPTION

Title of Invention

PATTERN FORMING METHOD, ACTINIC RAY-SENSITIVE OR RADIATION- SENSITIVE RESIN COMPOSITION, RESIST FILM, ELECTRONIC DEVICE MANUFACTURING METHOD USING THE SAME, AND ELECTRONIC DEVICE

Technical Field

The present invention relates to a pattern forming method, an actinic ray-sensitive or radiation- sensitive resin composition used therein, a resist film, an electronic device manufacturing method using the same, and an electronic device. More specifically, the present invention relates to a resist pattern forming method suitable for lithography in the process of producing a semiconductor such as IC or the production of a liquid crystal device or a circuit board such as thermal head and further in other photo-fabrication processes, an actinic ray-sensitive or radiation-sensitive resin composition used in the pattern forming method, a resist film, an electronic device manufacturing method using the same, and an electronic device. Above all, the present invention relates to a resist pattern forming method suitable for exposure by an ArF exposure apparatus or an ArF immersion-type projection exposure apparatus each using a light source that emits a far ultraviolet ray having a wavelength of 300 nm or less, an actinic ray-sensitive or radiation-sensitive resin composition used in the pattern forming method, a resist film, an electronic device manufacturing method, and an electronic device.

Background Art

Since the advent of a resist for KrF excimer laser (248 nm), a pattern forming method utilizing chemical amplification is used so as to compensate for sensitivity reduction due to light absorption. For example, in the positive chemical amplification method, first, a photoacid generator contained in the exposed area decomposes upon irradiation with light to produce an acid and in the course of baking or the like after exposure (PEB: Post Exposure Bake), an alkali-insoluble group contained in the photosensitive composition is changed into an alkali-soluble group by the catalytic action of the acid generated. Thereafter, development is performed using , for example, an alkali solution, whereby the exposed area is removed and a desired pattern is obtained.

As for the alkali developer used in the method above, various developers have been proposed. For example, as the alkali developer, an aqueous alkali developer of 2.38 mass% TMAH (aqueous tetramethylammonium hydroxide solution) is being used for general purposes.

Miniaturization of a semiconductor device has shown progress in shortening the wavelength of the exposure light source and increasing the numerical aperture (higher NA) of the projection lens, and an exposure machine using an ArF excimer laser having a wavelength of 193 nm as the light source has been so far developed. As a technique to more increase the resolution, a method of filling the space between the projection lens and the sample with a high refractive-index liquid (hereinafter, sometimes referred to as an "immersion liquid") (that is, an immersion method) has been proposed. Furthermore, EUV lithography of performing exposure to ultraviolet light at a shorter wavelength (13.5 nm) has been also proposed.

For example, in the positive chemical amplification method, for the purpose of enhancing the performance of the resist composition used in fine pattern formation, more specifically, for the purpose such as reducing the change in exposure latitude with aging after exposure until post-heating or reducing the change in sensitivity between during immersion exposure and during normal exposure, a technique of using a resin exhibiting basicity has been proposed (see, for example, JP-A-2006-276851 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), Japanese Patent No. 4571598, Korean Unexamined Patent Publication No. 2009-0072015 and JP-A-201 1-191741).

In the positive image forming method, an isolated line or dot pattern can be successfully formed, but when an isolated space or fine hole pattern is formed, the profile of the pattern is liable to be deteriorated.

In recent years, a pattern forming method using an organic solvent-containing developer (organic developer) is being also developed (see, for example, JP-A-2011-123469 and International Publication No. 201 1/122336). For example, in JP-A-2011-123469 and International Publication No. 201 1/122336, a pattern forming method including a step of coating a substrate with a resist composition capable of decreasing the solubility for an organic developer upon irradiation with an actinic ray or radiation, an exposure step, and a step of performing development by using an organic developer is disclosed. It is indicated that according to such a method, a high-definition fine pattern can be stably formed. Summary of Invention

In recent years, a need for miniaturization of a contact hole is furthermore abruptly increasing, and to meet this need, in the case of forming, for example, a pattern having an ultrafine space width or hole diameter (for example, 60 nm or less) in a resist pattern, more improvements are required in the local pattern dimension uniformity and exposure latitude. In addition, the pre-bridge dimension (the minimum dimension below which a bridge defect is generated) is also required to be more improved.

The present invention has been made by taking these problems into account, and an object of the present invention is to provide a pattern forming method capable of forming a pattern having an ultrafine space width or hole diameter (for example, 60 nm or less) in the state of the local pattern dimension uniformity, exposure latitude and pre-bridge dimension performance being excellent, an actinic ray-sensitive or radiation-sensitive resin composition used therein, a resist film, an electronic device manufacturing method using the same, and an electronic device.

The present invention includes the following configurations, and the above- described object of the present invention is attained by these configurations.

[ 1 ] A pattern forming method comprising:

(i) a step of forming a film by using an actinic ray-sensitive or radiation- sensitive resin composition containing (A) a resin having a weight average molecular weight of 7,000 or more and having (I) a structure containing a group having basicity or capable of decomposing by an action of an acid to increase basicity and (II) a structure being different from the structure (I) and containing a group capable of decomposing by the action of an acid to produce a polar group, and (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation,

(ii) a step of exposing the film, and

(iii) a step of developing the exposed film by using an organic solvent-containing developer to form a negative pattern.

[2] The pattern forming method as described in [1] above,

wherein the structure (II) in the resin (A) is a repeating unit having a group capable of decomposing by the action of an acid to produce a polar group, and

the resin (A) is a resin containing the repeating unit having a group capable of decomposing by the action of an acid to produce a polar group in an amount of 50 mol% or more based on all repeating units in the resin (A). [3]. The pattern forming method as described in [1] or [2] above,

wherein the actinic ray-sensitive or radiation-sensitive resin composition does not contain (C) a resin different from the resin (A) and capable of increasing the polarity by the action of an acid to decrease the solubility for an organic solvent-containing developer.

[4] The pattern forming method as described in any one of [1] to [3] above,

wherein the structure (I) in the resin (A) is (I) a repeating unit containing, in the side chain, a group having basicity or capable of decomposing by the action of an acid to increase basicity.

[5] The pattern forming method as described in any one of [1] to [3] above,

wherein the structure (I) in the resin (A) is a terminal structure being bonded to the main chain of the resin (A) and containing a group having basicity or capable of decomposing by the action of an acid to increase basicity.

[6] The pattern forming method as described in any one of [1] to [5] above,

wherein the actinic ray-sensitive or radiation-sensitive resin composition further contains (N) a basic compound or an ammonium salt compound, whose basicity decreases upon irradiation with an actinic ray or radiation.

[7] The pattern forming method as described in any one of [1] to [6] above,

wherein the actinic ray-sensitive or radiation-sensitive resin composition further contains (D) a hydrophobic resin different from the resin (A).

[8] The pattern forming method as described in any one of [1] to [7] above,

wherein the developer is a developer containing at least one kind of an organic solvent selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, an amide-based solvent and an ether-based solvent.

[9] The pattern forming method as described in any one of [1] to [8] above, which further comprises:

(iv) a step of rinsing the film by using a rinsing solution containing an organic solvent.

[10] The pattern forming method as described in any one of [1] to [9] above,

wherein the exposure in the step (ii) is immersion exposure.

[11] An actinic ray-sensitive or radiation-sensitive resin composition used in the pattern forming method described in any one of [1] to [10] above.

[12] A resist film formed of the actinic ray-sensitive or radiation-sensitive resin composition described in [11] above. [13] A method for manufacturing an electronic device, comprising the pattern forming method described in any one of [1] to [10] above.

[14] An electronic device manufactured by the manufacturing method of an electronic device described in [13] above.

The present invention preferably further includes the following configurations.

[15] The pattern forming method as described in [7] above, wherein the resin (D) is a resin containing a fluorine atom and/or a silicon atom.

[16] The pattern forming method as described in [7] above, wherein the resin (D) is a resin substantially free from a fluorine atom and a silicon atom.

[17] The pattern forming method as described in any one of [1] to [10], [15] and [16] above, wherein the exposure in the step (ii) is ArF exposure.

[18] The actinic ray-sensitive or radiation-sensitive resin composition as described in [11] above, which is a chemical amplification resist composition for organic solvent development.

[19] The actinic ray-sensitive or radiation-sensitive resin composition as described in [11] and [18] above, which is for immersion exposure.

According to the present invention, a pattern forming method capable of forming a pattern having an ultrafine space width or hole diameter (for example, 60 nm or less) in the state of the local pattern dimension uniformity, exposure latitude and pre-bridge dimension performance being excellent, an actinic ray-sensitive or radiation-sensitive resin composition used therein, a resist film, an electronic device manufacturing method using the same, and an electronic device can be provided.

Description of Embodiments

The mode for carrying out the present invention is described below.

In the description of the present invention, when a group (atomic group) is denoted without specifying whether substituted or unsubstituted, the group encompasses both a group having no substituent and a group having a substituent. For example, "an alkyl group" encompasses not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

In the description of the present invention, the "actinic ray" or "radiation" means, for example, a bright line spectrum of mercury lamp, a far ultraviolet ray typified by excimer laser, an extreme-ultraviolet ray (EUV light), an X-ray or an electron beam (EB). Also, in the present invention, the "light" means an actinic ray or radiation.

Furthermore, in the description of the present invention, unless otherwise indicated, the "exposure" encompasses not only exposure to a mercury lamp, a far ultraviolet ray typified by excimer laser, an extreme ultraviolet ray, an X-ray, EUV light or the like but also lithography with a particle beam such as electron beam and ion beam.

The pattern forming method of the present invention comprises:

(i) a step of forming a film by Using an actinic ray-sensitive or radiation- sensitive resin composition containing (A) a resin having (I) a structure containing a group having basicity or capable of decomposing by an action of an acid to increase basicity and (II) a structure being different from the structure (I) and containing a group capable of decomposing by the action of an acid to produce a polar group, and (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation,

(ii) a step of exposing the film, and

The reason why a pattern having an ultrafine space width or hole diameter (for example, 60 nm or less) can be formed in the state of the local pattern dimension uniformity, exposure latitude and pre-bridge dimension performance being excellent by the pattern forming method above is not clearly known but is presumed as follows.

In the negative pattern forming method using an organic solvent-containing developer, the dissolution contrast for the developer between an exposed area and an unexposed area is generally low and partial dissolution of the pattern boundary part readily occurs to worsen the local pattern dimension uniformity and exposure latitude.

The acid generated in the exposed area diffuses and since the above-described dissolution contrast is reduced when a reaction of the resin and the acid takes place also in the unexposed area, a chemical amplification resist composition usually contains a basic compound so as to scavenge the acid in the unexposed area.

However, when the basic compound is dissolved out of the resist film obtained from the resist composition into the immersion liquid or the like at the exposure, the function of scavenging the acid in the unexposed area is impaired.

On the other hand, in the present invention, a component having basicity or capable of decomposing by the action of an acid to increase basicity is incorporated as a group into the resin, so that the component can be prevented from dissolving out into the immersion liquid or the like at the immersion exposure. This is considered to make it possible to unfailingly scavenge the acid in the unexposed area and increase the above-described dissolution contract, leading to the fact that the local pattern dimension uniformity and exposure latitude are excellent.

Also, as described above, the acid can be unfailingly scavenged in the unexposed area and therefore, a reaction causing decomposition by the action of an acid to produce a polar group hardly occurs in the resin of the unexposed area. This is considered to enable unfailing removal of the unexposed area with an organic solvent-containing developer, resulting in excellent pre-bridge dimension performance.

Furthermore, the weight average molecular weight of the resin is sufficiently large (7,000 or more), so that a precise pattern can be formed without a problem caused by a low- molecular-weight polymer, such as excessive dissolution in an organic developer.

Meanwhile, as described above, when a fine hole pattern is formed by a positive image forming method, the pattern profile is liable to deteriorate and formation of an ultrafine pattern (for example, having a space width or hole diameter of 60 nm or less) is virtually impossible. This is because in the case of forming such a fine pattern by a positive image forming method, the region in which a space part or a hole part is intended to form becomes an exposed area and it is optically almost impossible to expose and resolve an ultrafine region.

The pattern forming method of the present invention preferably further comprises (iv) a step of rinsing the film by using an organic solvent-containing rinsing solution.

The rinsing solution is preferably a rinsing solution containing at least one kind of an organic solvent selected from the group consisting of a hydrocarbon-based solvent, a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, an amide-based solvent and an ether-based solvent.

The pattern forming method of the present invention preferably has (v) a heating step after the exposure step (ii).

The resin (A) is also a resin capable of increasing the polarity by the action of an acid to increase the solubility for an alkali developer. Accordingly, the pattern forming method may further comprises (vi) a step of performing development by using an alkali developer.

In the pattern forming method of the present invention, the exposure step (ii) may be performed a plurality of times.

In the pattern forming method of the present invention, the heating step (v) may be performed a plurality of times.

The resist film of the present invention is a film formed of the above-described actinic ray-sensitive or radiation-sensitive resin composition, and this is a film formed, for example, by coating the actinic ray-sensitive or radiation-sensitive resin composition on a base material.

The actinic ray-sensitive or radiation-sensitive resin composition which can be used in the present invention is described below.

The present invention also relates to the actinic ray-sensitive or radiation-sensitive resin composition described below.

The actinic ray-sensitive or radiation-sensitive resin composition according to the present invention is used for negative development (development where the solubility for developer is decreased upon exposure, as a result, the exposed area remains as a pattern and the unexposed area is removed) particularly in the case of forming a pattern having an ultrafme space width or hole diameter (for example, 60 nm or less) in a resist film. That is, the actinic ray-sensitive or radiation-sensitive resin composition according to the present invention can be an actinic ray-sensitive or radiation-sensitive resin composition for organic solvent development, which is used for development using an organic solvent-containing developer. The term "for organic solvent development" as used herein means usage where the composition is subjected to at least a step of performing development by using an organic solvent-containing developer.

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention is typically a resist composition and is preferably a negative resist composition (that is, a resist composition for organic solvent development), because particularly high effects can be obtained. Also, the composition according to the present invention is typically a chemical amplification resist composition.

[1] (A) Resin having (I) a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity and (II) a structure being different from the structure (I) and containing a group capable of decomposing by the action of an acid to produce a polar group

The actinic ray-sensitive or radiation- sensitive resin composition for use in the pattern forming method of the present invention contains (A) a resin having (I) a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity and (II) a structure being different from the structure (I) and containing a group capable of decomposing by the action of an acid to produce a polar group (hereinafter, sometimes referred to as "acid-decomposable resin (A)").

The group having basicity or capable of decomposing by the action of an acid to increase basicity preferably contains a nitrogen atom as an atom that develops basicity.

However, when the composition of the present invention is used particularly for ArF exposure, in view of transparency to ArF light, the group having basicity or capable of decomposing by the action of an acid to increase basicity preferably has not aromaticity and more preferably contains no nitrogen-containing aromatic ring.

The group having basicity contained in the structure (I) of the acid-decomposable resin (A) includes, for example, a basic group represented by any one of the following formulae (A) to (E):

R I ²⁰¹ * I * I . w _A ⁱt . * R i ²⁰⁴ _rl Rl ²⁰⁵

* — R²⁰² *— N— C=N— * *=c— _{N =}c— * *=C— N— * R²⁰³— C— — C— R²⁰⁶

* I * I

(A) (B) (C) (D) _(E)

901 909

In formula (A), each of R and R independently represents a hydrogen atom, an alkyl group (preferably having a carbon number of 1 to 20), a cycloalkyl group (preferably having a carbon number of 3 to 20) or an aryl group (having a carbon number of 6 to 20).

In formula (E), each of R²⁰³, R²⁰⁴, R²⁰⁵ and R²⁰⁶ independently represents an alkyl group (preferably having a carbon number of 1 to 20) or a cycloalkyl group (preferably having a carbon number of 3 to 20).

* represents a bond connected to another atom constituting the structure (I).

901 909

In the structure represented by formula (A), R and R may combine with each other to form a ring.

In the structures represented by formulae (B) to (D), two or more members out of bonds from carbon bond and bonds from nitrogen atom may combine with each other to form a ring.

In the structure represented by formula (E), two or more members out of R²⁰³, R²⁰⁴,

205 206

R , R , bonds from carbon atom and bonds from nitrogen atom may combine to form a ring.

In formula (A), the alkyl group of R²⁰¹ and R²⁰² is preferably a linear or branched alkyl group having a carbon number of 1 to 20, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n- hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, an n- eicosyl group, an i-propyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, and a tert-dodecyl group.

201 202

The cycloalkyl group of R and R is preferably a cycloalkyl group having a carbon number of 3 to 20, and examples thereof include a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

Among alkyl groups and cycloalkyl groups of R and R , a linear alkyl group having a carbon number of 1 to 10 and a cycloalkyl group having a carbon number of 4 to 8 are preferred.

201 202

The aryl group of R and R is preferably an aryl group having a carbon number of 6 to 20, and examples thereof include a phenyl group, a toluyl group, a benzyl group, a methylbenzyl group, a xylyl group, a mesityl group, a naphthyl group, and an anthryl group.

The alkyl group, cycloalkyl group and aryl group of R ^u' and R ^u may further have a substituent, and examples of the substituent include a halogen atom, a hydroxyl group, an amino group, a carboxyl group, a cyano group, a nitro group, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an arylcarbonyl group, an alkoxyalkyl group, an aryloxyalkyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, and a lactone group.

In formula (E), specific examples of the alkyl group and cycloalkyl group of R²⁰³, R²⁰⁴, R²⁰⁵ and R²⁰⁶ are the same as specific examples of the alkyl group and cycloalkyl group, respectively, of R²⁰¹ and R²⁰².

The alkyl group and cycloalkyl group of R²⁰³, R²⁰⁴, R²⁰⁵ and R²⁰⁶ may further have a substituent, and specific examples of the substituent are the same as specific examples of the

201 202

substituent which R and R .may further have.

In the groups represented by formulae (A) to (E), the bond from carbon atom and/or nitrogen atom is connected to another atom constituting the structure (I).

Also, as described above, in the group represented by formula (A), R²⁰¹ and R²⁰² may combine with each other to form a ring; in the groups represented by formulae (B) to (D), two or more members out of bonds from carbon atom and bonds from nitrogen atom may combine with each other to form a ring; and in the structure represented by formula (E), two or more members out of R²⁰³, R²⁰⁴, R²⁰⁵, R²⁰⁶, bonds from carbon atom and bonds from nitrogen atom may combine with each other to form a ring.

The ring above includes an aromatic or non-aromatic nitrogen-containing heterocyclic ring. The nitrogen-containing heterocyclic ring includes a 3- to 10-membered ring and is preferably a 4- to 8-membered ring, more preferably a 5- or 6-membered ring. Such a ring may further have a substituent, and specific examples thereof are the same as

901 909

specific examples of the substituent which R and R .may further have.

The group having basicity includes, for example, a group derived from primary, secondary or tertiary aliphatic amines, aromatic amines or heterocyclic amines.

Examples of the aliphatic amines include ethylamine, n-propylamine, sec- butylamine, tert-butylamine, hexylamine, cyclohexylamine, octylamine, dodecylamine, ethylenediamine, tetraethylenepentamine, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, didodecylamine, N,N- dimethylethylenediamine, Ν,Ν-dimethyltetraethylenepentamine, trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tripentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, tridecylamine, tridodecylamine, Ν,Ν,Ν',Ν'-tetramethylmethylenediamine, Ν,Ν,Ν',Ν'- tetramethylethylenediamine, Ν,Ν,Ν',Ν'-tetramethyltetraethylenepentamine, dimethylethylamine, methylethylpropylamine, benzylamine, phenethylamine, benzyldimethylamine, monoethanolamine, diethanolamine, triethanolamine, N- ethyldiethylamine, Ν,Ν-diethylethanolamine, triisopropanolamine, 2-aminoethanol, 3-amino- 1-propanol, and 4-amino-l-butanol.

Examples of the aromatic amines and heterocyclic amines include an aniline derivative, diphenyl(p-tolyl)amine, methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene, a pyrrole derivative, an oxazole derivative, a thiazole derivative, an imidazole derivative a pyrazole derivative, a frazane derivative, a pyrroline derivative, a pyrrolidine derivative, an imidazoline derivative, an imidazolidine derivative, a pyridine derivative (preferably 2-(2-hydroxyethyl)pyridine), a pyridazine derivative, a pyrimidine derivative, a pyrazine derivative, a pyrazoline derivative, a pyrazolidine derivative, a piperidine derivative, a piperazine derivative (preferably l-(2-hydroxyethyl)piperazine and l-[2-(2-hydroxyethoxy)ethyl]piperazine), a morpholine derivative (preferably 4-(2- hydroxyethyl)morpholine), an indole derivative, an isoindole derivative, a lH-indazole derivative, an indoline derivative, a quinoline derivative, an isoquinoline derivative, a cinnoline derivative, a quinazoline derivative, a quinoxaline derivative, a phthalazine derivative, a purine derivative, a pteridine derivative, a carbazole derivative, a phenanthridine derivative, an acridine derivative, a phenazine derivative, a 1 , 10-phananthroline derivative, an adenine derivative, an adenosine derivative, a guanine derivative, a guanosine derivative, an uracil derivative, and a uridine derivative.

The group capable of decomposing by the action of an acid to increase basicity contained in the structure (I) of the acid-decomposable resin (A) includes, for example, a group where a basic group represented by any one of formulae (A) to (E) is protected by "a group decreasing the basicity of the basic group and at the same time, capable of decomposing and leaving by the action of an acid", and the group is preferably a structure represented by the following formula (Ap):

In formula (Ap), each of Ra, Rbi, Rb₂ and Rb₃ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. Two members out of Rbj to Rb₃ may combine with each other to form a ring. However, it is not allowed that all of Rbi to Rb₃ are a hydrogen atom at the same time.

Rc represents a single bond or a divalent linking group.

x represents 0 or 1, y represents 1 or 2, and x+y=2.

When x=l, Ra and Rc may combine with each other to form a nitrogen-containing heterocyclic ring.

Specific examples of the alkyl group, cycloalkyl group and aryl group of Ra, Rbi, Rb₂ and Rb₃ are the same as specific examples of the alkyl group, cycloalkyl group and aryl group of R^' and R^ in the group represented by formula (A).

Specific examples of the aralkyl group of Ra, Rbi, Rb₂ and Rb₃ include an aralkyl group preferably having a carbon number of 6 to 12, such as benzyl group, phenethyl group, naphthylmethyl group, naphthylethyl group and naphthylbutyl group.

Each of Ra, Rbi, Rb₂ and Rb₃ is preferably a linear or branched alkyl group, a cycloalkyl group or an aryl group, more preferably a linear or branched alkyl group or a cycloalkyl group.

Rc is preferably a divalent linking group having a carbon number of 2 to 12 (more preferably a carbon number of 2 to 6, still more preferably a carbon number of 2 to 4), and examples thereof include an alkylene group, a phenylene group, an ether group, an ester group, an amide group, and a group formed by combining two or more thereof.

Each of Ra, Rbj, Rb₂, Rb₃ and Rc may further have a substituent and specific examples of the substituent include a halogen atom (e.g., fluorine atom), a hydroxyl group, a nitro group, a cyano group, a carboxy group, a carbonyl group, a cycloalkyl group (preferably having a carbon number of 3 to 10), an aryl group (preferably having a carbon number of 6 to 14), an alkoxy group (preferably having a carbon number of 1 to 10), an acyl group (preferably having a carbon number of 2 to 20), an acyloxy group (preferably having a carbon number of 2 to 10), an alkoxycarbonyl group (preferably having a carbon number of 2 to 20), an aminoacyl group (preferably having a carbon number of 2 to 10), an amino group, a pyrrolidino group, a piperidino group, a morpholino group, and a silicon atom-containing group. The cyclic structure in the aryl group, cycloalkyl group and the like may further have an alkyl group (preferably having a carbon number of 1 to 10) as a substituent. The aminoacyl group may further have an alkyl group (preferably having a carbon number of 1 to 10) as a substituent.

In the case where both of two members out of Rbi, Rb₂ and Rb₃ are a hydrogen atom, the remaining one member is preferably an aryl group, and examples of the aryl group include a phenyl group and a naphthyl group.

The nitrogen-containing heterocyclic ring formed by combining Ra and Rc with each other includes an aromatic or non-aromatic nitrogen-containing heterocyclic ring (preferably having a carbon number of 3 to 20). Examples of such a nitrogen-containing heterocyclic ring include a ring corresponding to a heterocyclic compound such as pyrrolidine, piperidine, morpholine, 1,4,5,6-tetrahydropyrimidine, 1,2,3,4-tetrahydroquinoline, 1,2,3,6- tetrahydropyridine, homopiperazine, 4-azabenzimidazole, benzotriazole, 5-azabenzotriazole, lH-l,2,3-triazole, 1 ,4,7-triazacyclononane, tetrazole, 7-azaindole, indazole, benzimidazole, imidazo[l,2-a]pyridine, (l S,4S)-(+)-2,5-diazabicyclo[2.2.1]heptane, 1,5,7- triazabicyclo[4.4.0]dec-5-ene, indole, indoline, 1,2,3,4-tetrahydroquinoxaline, perhydroquinoline and 1 ,5,9-triazacyclododecane.

The ring formed by combining two members out of Rbi to Rb₃ is preferably a monocyclic cycloalkane ring such as cyclopentane ring and cyclohexane ring, or a polycyclic cycloalkane ring such as norbornane ring, tetracyclodecane ring, tetracyclododecane ring and adamantane ring, more preferably a monocyclic cycloalkane ring having a carbon number of 5 to 6.

Each of the nitrogen-containing heterocyclic ring formed by combining Ra and Rc with each other and the ring formed by combining two members out of Rbi to Rb₃ may further have one or more kinds of substituents or one or more substituents, and specific examples of the substituent are the same as specific examples of the substituent which Ra, Rb_\, Rb₂, Rb₃ and Rc may further have.

The group represented by formula (Ap) can be easily synthesized using a general amine structure-containing group by the method described, for example, in Protective Groups in Organic Synthesis, 4th edition. A most general method is a method of causing a dicarbonic acid ester or a haloformic acid ester to act on an amine structure-containing group to obtain the compound. In the formulae, X represents a halogen atom, and definitions, and Ra, Rb], Rb₂, Rb₃ and Rc have the same meanings as Ra, Rbi, Rb₂, Rb₃ and Rc, respectively, in formula (Ap).

The (I) structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity includes (I) a repeating unit containing, in the side chain, a group having basicity or capable of decomposing by the action of an acid to increase basicity, and a terminal structure being bonded to the main chain of the resin (A) and containing a group having basicity or capable of decomposing by the action of an acid to increase basicity.

The (I) repeating unit containing, in the side chain, a group having basicity or capable of decomposing by the action of an acid to increase basicity can be obtained using (1) a monomer containing a group having basicity or (Γ) a monomer containing a group capable of decomposing by the action of an acid to increase basicity, as at least one kind of a polymerizable component in the synthesis of the resin (A).

The terminal structure being bonded to the main chain of the resin (A) and containing a group having basicity or capable of decomposing by the action of an acid to increase basicity can be obtained using (2) a compound containing a group having basicity or (2') a compound containing a group capable of decomposing by the action of an acid to increase basicity, as a chain transfer agent in the synthesis of the resin (A), or using (3) a compound containing a group having basicity or (3') a compound containing a group capable of decomposing by the action of an acid to increase basicity, as a polymerization initiator in the synthesis of the resin (A).

The repeating unit corresponding to the (1) monomer containing a group having basicity includes, for example, repeating units represented by the following formulae (PI) to (P3):

( P 1 ) ( P 2 ) ( P 3 )

In formulae (PI) to (P3), Xi represents a hydrogen atom or an alkyl group.

X₂ represents a single bond or a divalent linking group.

Ri represents a group having basicity.

R₂ represents a hydrogen atom or an alkyl group.

Ri and R₂ may combine with each other to form a ring.

In formulae (PI) to (P3), the alkyl group of Xi and R₂ is preferably an alkyl group having a carbon number of 1 to 10 and may be substituted with a fluorine atom, a chlorine atom, a hydroxyl group or the like.

The divalent linking group of X₂ includes, for example, an alkylene group, an arylene group, an oxy group and a carbonyl group, which may be used individually or in combination of two or more kinds thereof. The group having basicity of Ri includes those recited above as the group having basicity.

More specifically, the repeating unit corresponding to the (1) monomer containing a group having basicity includes, for example, repeating units represented by the following formulae P4) to (P 10):

In formulae (P4) to (P10), Xi has the same meaning as Xi i formula (PI).

Each of R₃ to R₉ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or an aralkyl group. R₃ and R₄ may combine with each other to form a ring. Each of the pair of R₅ and R6 and the pair of R₇ and R₈ may combine together to form a ring (preferably an aromatic ring).

Z represents an alkylene group or -NH-.

The alkyl group of R₃ to R₉ is preferably an alkyl group having a carbon number of 1 to 10; the cycloalkyl group is preferably a cycloalkyl group having a carbon number of 1 to 20; the alkenyl group is preferably an alkenyl group having a carbon number of 1 to 10; the aryl group is preferably an aryl group having a carbon number of 6 to 20; and the aralkyl group is preferably an aralkyl group having a carbon number of 7 to 20. These groups may be substituted with a fluorine atom, a chlorine atom, a hydroxyl group, a carbonyl group, a cyano group, a sulfone group or the like.

Specific examples of the repeating unit corresponding to the (1) monomer containing a group having basicity are illustrated below, but the present invention is not limited thereto.

Rx is H, CH₃ or CF₃.

The repeating unit corresponding to the ( ) monomer containing a group capable of decomposing by the action of an acid to increase basicity includes, for example, repeating units represented by the following formulae (P'l) to (P'3):

(P'2) (P'3)

In formulae (P'l) to (P'3), X_\ represents a hydrogen atom or an alkyl group.

X₂ represents a single bond or a divalent linking group.

R₂ represents a hydrogen atom or an alkyl group.

R₃ represents a group capable of decomposing by an action of an acid to basicity.

R₂ and R₃ may combine with each other to form a ring.

In formulae (P'l) to (P'3), the alkyl group of Xi and R₂ is preferably an alkyl group having a carbon number of 1 to 10 and may be substituted with a fluorine atom, a chlorine atom, a hydroxyl group or the like. The divalent linking group of X₂ includes, for example, an alkylene group, an arylene group, an oxy group and a carbonyl group, which may be used individually or in combination of two or more kinds thereof.

The group capable of decomposing by the action of an acid to increase basicity of R₃ includes those recited above as the group capable of decomposing by the action of an acid to increase basicity. Specific examples of the repeating unit corresponding to the (Γ) monomer containing a group capable of decomposing by the action of an acid to increase basicity are illustrated below, but the present invention is not limited thereto.

In specific examples, Rx represents a hydrogen atom, a methyl group or a trifluoromethyl group.

The content of the (I) repeating unit containing, in the side chain, a group having basicity or capable of decomposing by the action of an acid to increase basicity is preferably from 1 to 65 mol%, more preferably from 3 to 60 mol%, still more preferably from 5 to 50 mol%, based on all repeating units in the resin (A).

The "(2) compound containing a group having basicity" as a chain transfer agent usable for obtaining the terminal structure being bonded to the main chain of the resin (A) and containing a group having basicity includes, for example, a compound represented by the following formula (Tl):

In formula (Tl), each of R₉ and Ri₀ independently represents a hydrogen atom or an alkyl group.

z represents an integer of 1 to 8.

X₃ represents a (z+l)-valent linking group.

R₉ and Ri₀ may combine with each other to form a ring.

The pair of X₃ and R₉ or the pair of X₃ and Rio may combine with each other to form a ring.

When z is an integer of 2 or more, each R₉ or each R₁₀ may be the same as or different from every other R₉ or Rio.

The alkyl group of R₉ and R]₀ is preferably an alkyl group having a carbon number of 1 to 10 and may be substituted with a fluorine atom, a chlorine atom, a hydroxyl group or the like.

The (z+l)-valent linking group of X₃, when z=l , includes, for example, an alkylene group, an arylene group, an oxy group and a carbonyl group, which may be used individually or in combination of two or more kinds thereof.

When z=2 or more, the linking group includes a group formed by removing arbitrary (z-1) hydrogen atoms from the above-described divalent linking group in case of z=l .

Specific examples of the (2) compound containing a group having basicity include the following compounds.

The "(2') compound containing a group capable of decomposing by the action of an acid to increase basicity" as a chain transfer agent usable for obtaining the terminal structure being bonded to the main chain of the resin (A) and containing a group capable of decomposing by the action of an acid to increase basicity includes a compound wherein in formula (T), at least either one of R₉ and R₁₀ is "a group decreasing the basicity of nitrogen atom and at the same time, capable of decomposing and leaving by the action of an acid".

Specifically, the (2') compound containing a structure capable of decomposing by the action of an acid to increase basicity includes, for example, a compound represented by the following formula (T2):

In formula (T2), each of Ra, Rbi, Rb₂ and Rb₃ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. Two members out of Rbi to Rb₃ may combine with each other to form a ring. However, it is not allowed that all of Rbi to Rb₃ are a hydrogen atom at the same time.

X₃ represents a (z+l)-valent linking group.

When z is an integer of 2 or more, each group represented by -N(Ra)(- COOC(Rbi)(Rb₂)(Rb₃)) may be the same as or different from every other group represented by -N(Ra)(-COOC(Rbi)(Rb₂)(Rb₃)).

x represents 0 or 1, y represents 1 or 2, and x+y=2. z represents an integer of 1 to 8.

When x=l, Ra and X₃ may combine with each other to form a nitrogen-containing heterocyclic ring.

Specific examples and preferred examples of Ra, Rb_1; Rb₂ and Rb₃ are the same as specific examples and preferred examples of Ra, Rbi, Rb₂ and Rb₃ in formula (Ap).

Specific examples and preferred examples of X₃ are the same as specific examples and preferred examples of X₃ in formula (Tl).

The nitrogen-containing heterocyclic ring formed by combining Ra and X₃ with each other, the ring formed by combining two members out of Rbi to Rb₃, and the substituent which these may have are the same as the nitrogen-containing heterocyclic ring formed by combining Ra and Rc with each other, the ring formed by combining two members out of Rbi to Rb₃, and the substituent which these may further have, which are recited above in formula (Ap).

Specific examples of the (2') compound containing a group capable of decomposing by the action of an acid to increase basicity include the following compounds.

By using the compound (2) or the compound (2') as a chain transfer agent at the time of synthesizing the acid-decomposable resin (A), a terminal structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity can be bonded to the main chain of the acid-decomposable resin (A).

The "(3) compound containing a group having basicity" as a polymerization initiator usable for obtaining a terminal structure being bonded to the main chain of the resin (A) and containing a group having basicity includes, for example, a compound represented by the following formula (II):

In formula (II), each of Rin, Rin, Rin and Rii₄ independently represents an alkyl group, and each of Ri₂i, Ri₂₂, Ri₃i, Ri₃₂, Ri₄i and Ri₄₂ independently represents a hydrogen atom or an alkyl group.

Each of the pair of Ri₂₁ and Ri₃₁, the pair of Ri₂₁ and Ri₄₁, and the pair of Ri₃₁ and Ri₄₁ may combine together to form a ring.

Each of the pair of Ri₂₂ and Ri₃₂, the pair of Ri₂₂ and Ri₄₂, and the pair of Ri₃₂ and Ri₄₂ may combine together to form a ring.

The alkyl group of Rin, Ri₁₂, Ri₁₃, Ri₁₄, Ri₂i, Ri₂₂, Ri₃i, Ri₃₂, Ri₄i and Ri₄₂ is preferably an alkyl group having a carbon number of 1 to 5, more preferably an alkyl group having a carbon number of 1 to 3. The alkyl group may further have a substituent, and examples of the substituent include a halogen atom, a hydroxyl group, an amino group, a carboxyl group, a cyano group, a nitro group, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an arylcarbonyl group, an alkoxyalkyl group, an aryloxyalkyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, and a lactone group.

The ring which may be formed by combining each of the pair of Ri₂₂ and Ri₃₂, the pair of Ri₂₂ and Ri₄₂, and the pair of Ri₃₂ and Ri₄₂ is preferably a 5- to 7-membered ring, more preferably a 5- or 6-membered ring.

Specific examples of the (3) compound containing a group having basicity include the following compounds:

The "(3') compound containing a group capable of decomposing by the action of an acid to increase basicity" as a polymerization initiator usable for obtaining a terminal structure being bonded to the main chain of the resin (A) and containing a group capable of decomposing by the action of an acid to increase basicity includes, for example, a compound represented by the following formula (12):

In formula (12), each of Rin, R1₁2, R113 and Ri₁₄ independently represents an alkyl group, and each of Ri₂i, Ri₂₂, Ri₃j and Ri₃₂ independently represents a hydrogen atom or an alkyl group.

Ri₂₁ and Ri₃i may combine with each other to form a ring.

R122 and Ri₃₂ may combine with each other to form a ring. Each of Rbi_!, Rb₂ and Rb₃ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. Two members out of Rbi to Rb₃ may combine with each other to form a ring. However, it is not allowed that all of Rbi to Rb₃ are a hydrogen atom at the same time.

Preferred examples of the alkyl group of Rin, Rij₂, Rii₃, Rii₄, Ri₂i, Ri₂₂, Ri₃₁ and Ri₃₂ are the same as preferred examples of the alkyl group of Rin, Ri₎₂, Rii₃, Ri₁ , Ri₂₎, Ri₂₂, Ri₃i and Ri₃₂ recited in formula (II).

The ring which may be formed by combining Ri₂₁ and Ri₃₁ with each other and the ring which may be formed by combining Ri₂₂ and Ri₃₂ with each other is preferably a 5- to 7- membered ring, more preferably a 5- or 6-membered ring.

Specific examples and preferred examples of Rb_{l 5} Rb₂ and Rb₃ are the same as specific examples and preferred examples of Rbi, Rb₂ and Rb₃ in formula (Ap).

The ring formed by combining two members out of Rbi to Rb₃, and the substituent which these may further have are the same as the ring formed by combining two members out of Rbi to Rb₃, and the substituent which these may further have, which are recited above in formula (Ap).

Examples of the (3') compound containing a group capable of decomposing by the action of an acid to increase basicity include the following compounds.

By using the compound (3) or the compound (3') as a polymerization initiator at the time of synthesizing the acid-decomposable resin (A), a terminal structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity can be bonded to the main chain of the acid-decomposable resin (A).

As for the monomers (1) and ( ) and the compounds (2), (3), (2') and (3'), a commercial product can be suitably used. Also, the monomer (Γ) and the compounds (2') and (3') may be synthesized, for example, by protecting the basic group in an existing basic compound by "a group decreasing the basicity of the basic group and at the same time, capable of decomposing and leaving by the action of an acid" according to a method pursuant to the production method of a group represented by formula (Ap) or the like.

As described above, the resin (A) contains (II) a structure being different from the structure (I) and containing a group capable of decomposing by the action of an acid to produce a polar group (hereinafter, sometimes referred to as "acid-decomposable group").

Accordingly, the resin (A) is a resin capable of increasing the polarity by the action of an acid to decrease the solubility for an organic solvent-containing developer.

The resin (A) can have an acid-decomposable group, for example, in the main chain or the side chain of the resin or in both the main chain and the side chain, and the structure (II) is preferably (II) a repeating unit having an acid-decomposable group. Here, the repeating unit (II) is different from the above-described (I) repeating unit containing, in the side chain, a group having basicity or capable of decomposing by the action of an acid to increase basicity.

Incidentally, the resin (A) is also a resin capable of increasing the polarity by the action of an acid to increase the solubility for an alkali developer.

The acid-decomposable group preferably has a structure where a polar group is protected by a group capable of decomposing and leaving by the action of an acid.

The polar group is not particularly limited as long as it is a group capable of becoming sparingly soluble or insoluble in an organic solvent-containing developer, but examples thereof include a carboxyl group, an acidic group (a group capable of dissociating in an aqueous 2.38 mass% tetramethylammonium hydroxide solution that is conventionally used as the developer for a resist) such as sulfonic acid group, and an alcoholic hydroxyl group.

The alcoholic hydroxyl group is a hydroxyl group bonded to a hydrocarbon group and indicates a hydroxyl group except for a hydroxyl group directly bonded on an aromatic ring (phenolic hydroxyl group), and an aliphatic alcohol substituted with an electron- withdrawing group such as fluorine atom at the a-position (for example, a fluorinated alcohol group (e.g., hexafluoroisopropanol group)) is excluded from the hydroxyl group. The alcoholic hydroxyl group is preferably a hydroxyl group having a pKa of 12 to 20.

The group preferred as the acid-decomposable group is a group where a hydrogen atom of the group above is substituted for by a group capable of leaving by the action of an acid.

Examples of the group capable of leaving by the action of an acid include - C(R₃₆)(R₃₇)(R₃₈), -C(R₃₆)(R₃₇)(OR₃₉) and -C(R₀₁)(R₀₂)(OR₃₉).

In the formulae, each of R₃ to R₃₉ independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group. R₃₆ and R₃ may combine with each other to form a ring.

Each of Roi and R₀₂ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.

The alkyl group of R₃₆ to R₃₉, and R₀₂ is preferably an alkyl group having a carbon number of 1 to 8, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a hexyl group, and an octyl group.

The cycloalkyl group of R₃₆ to R₃₉, Roi and R₀₂ may be monocyclic or polycyclic. The monocyclic cycloalkyl group is preferably a cycloalkyl group having a carbon number of 3 to 8, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The polycyclic cycloalkyl group is preferably a cycloalkyl group having a carbon number of 6 to 20, and examples thereof include an adamantyl group, a norbornyl group, an isoboronyl group, a camphanyl group, a dicyclopentyl group, an a-pinel group, a tricyclodecanyl group, a tetracyclododecyl group, and an androstanyl group. Incidentally, at least one carbon atom in the cycloalkyl group may be substituted with a heteroatom such as oxygen atom.

The aryl group of R₃₆ to R₃₉, R₀₁ and R₀₂ is preferably an aryl group having a carbon number of 6 to 10, and examples thereof include a phenyl group, a naphthyl group, and an anthryl group.

The aralkyl group of R₃₆ to R₃₉, Roi and Ro₂ is preferably an aralkyl group having a carbon number of 7 to 12, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.

The alkenyl group of R₃₆ to R₃₉, R₀i and R₀₂ is preferably an alkenyl group having a carbon number of 2 to 8, and examples thereof include a vinyl group, an allyl group, a butenyl group, and a cyclohexenyl group.

The ring formed by combining R₃₆ and R₃₇ is preferably a cycloalkyl group (monocyclic or polycyclic). The cycloalkyl group is preferably a monocyclic cycloalkyl group such as cyclopentyl group and cyclohexyl group, or a polycyclic cycloalkyl group such as norbornyl group, tetracyclodecanyl group, tetracyclododecanyl group and adamantyl group, more preferably a monocyclic cycloalkyl group having a carbon number of 5 or 6, still more preferably a monocyclic cycloalkyl group having a carbon number of 5.

The resin (A) preferably contains, as the repeating unit having an acid- decomposable group, a repeating unit represented by the following formula (I):

In formula (I), Xa represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom, each of R , and Ri_c independently represents an alkyl group or a cycloalkyl group, and two members out of R , Rib and Ri_c may combine to form a ring structure.

The alkyl group of Xa may have a substituent, and examples of the substituent include a hydroxyl group and a halogen atom (preferably fluorine atom).

The alkyl group of Xa is preferably an alkyl group having a carbon number of 1 to 4, and examples thereof include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group and a trifluoromethyl group, with a methyl group being preferred.

Xa is preferably a hydrogen atom or a methyl group.

The alkyl group of Ri_a, R^ and Rj_c is preferably an alkyl group having a carbon number of 1 to 4, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and tert-butyl group.

The cycloalkyl group of Ri_a, Rib and Ri_c is preferably a monocyclic cycloalkyl group such as cyclopentyl group and cyclohexyl group, or a polycyclic cycloalkyl group such as norbornyl group, tetracyclodecanyl group, tetracyclododecanyl group and adamantyl group.

The ring structure formed by combining two members out of Ri_a, Ri_b and R_lc is preferably a monocyclic cycloalkane ring such as cyclopentyl ring and cyclohexyl ring, or a polycyclic cycloalkane ring such as norbornane ring, tetracyclodecane ring, tetracyclododecane ring and adamantane group, more preferably a monocyclic cycloalkane ring having a carbon number of 5 or 6.

Each of R , R^ and R_lc is independently, preferably an alkyl group, more preferably a linear or branched alkyl group having a carbon number of 1 to 4.

Each of the groups above may further have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (having a carbon number of 1 to 4), a carboxyl group, and an alkoxycarbonyl group (having a carbon number of 2 to 6), and the carbon number of the substituent is preferably 8 or less.

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

In specific examples, Rx represents a hydrogen atom, CH₃, CF₃ or CH₂OH. Each of Rxa and Rxb represents an alkyl group having a carbon number 1 to 4. Z represents a substituent and when a plurality of Z are present, each Z may be the same as or different from every other Z. p represents 0 or a positive integer. Specific examples and preferred examples of Z are the same as specific examples and preferred examples of the substituent which may be substituted on each of the groups such as Rj_a to R_lc.

As for the repeating unit represented by formula (I), one kind may be used, or two or more kinds may be used in combination.

It is also preferred that the resin (A) contains a repeating unit represented by the following formula (AI):

In formula (AI), Xa] represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.

T represents a divalent linking group.

Each of Rxi to Rx₃ independently represents an alkyl group or a cycloalkyl group. Two members out

to Rx₃ may combine to form a ring structure.

Examples of the divalent linking group of T include an alkylene group, a -COO-Rt- group, a -O-Rt- group, and a phenylene group. In the formulae, Rt represents an alkylene group or a cycloalkylene group.

T is preferably a -COO-Rt- group. Rt is preferably an alkylene group having a carbon number of 1 to 5, more preferably a -CH₂- group, -(CH₂)₂- group or a -(CH₂)₃- group.

Specific examples and preferred examples of the alkyl group of Xai are the same as specific examples and preferred examples of the alkyl group of Xa in formula (I).

Specific examples and preferred examples of the alkyl group and cycloalkyl group of Rxi to Rx₃ are the same as specific examples and preferred examples of the alkyl group and cycloalkyl group of R)_a to Rj_c in formula (I).

Specific examples and preferred examples of the ring structure formed by combining two members out of Rx( to Rx₃ are the same as specific examples and preferred examples of the ring structure formed by combining two members out of R]_a to R_lc in formula (I).

Each of the groups above may have a substituent, and examples of the substituent include an alkyl group (having a carbon number of 1 to 4), a cycloalkyl group (having a carbon number of 3 to 8), a halogen atom, an alkoxy group (having a carbon number of 1 to 4), a carboxyl group, and an alkoxycarbonyl group (having a carbon number of 2 to 6). The carbon number is preferably 8 or less. Above all, from the standpoint of more enhancing the dissolution contrast for an organic solvent-containing developer between before and after acid- induced decomposition, the substituent is preferably a group free from a heteroatom such as oxygen atom, nitrogen atom and sulfur atom (for example, preferably not an alkyl group substituted with a hydroxyl group), more preferably a group composed of Only a hydrogen atom and a carbon atom, still more preferably a linear or branched alkyl group or a cycloalkyl group.

Specific examples of the repeating unit represented by formula (AI) are illustrated below, but the present invention is not limited to these specific examples.

In specific examples, Xa] represents a hydrogen atom, CH₃, CF₃ or CH₂OH. Z represents a substituent and when a plurality of Z are present, each Z may be the same as or different from every other Z. p represents 0 or a positive integer. Specific examples and preferred examples of Z are the same as specific examples and preferred examples of the substituent which may be substituted on each of the groups such as Rxj to Rx₃.

It is also preferred that the resin (A) contains, as the repeating unit having an acid- decomposable group, a repeating unit represented by the following formula (IV):

In formula (IV), Xb represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.

Each of Ryi to Ry₃ independently represents an alkyl group or a cycloalkyl group, and two members out of R i to Ry₃ may combine to form a ring.

Z represents a (p+l)-valent linking group having a polycyclic hydrocarbon structure which may have a heteroatom as a ring member. It is preferred that Z does not contain an ester bond as an atomic group constituting the polycyclic ring (in other words, it is preferred that Z does not contain a lactone ring as a ring constituting the polycyclic ring).

Each of L₄ and L₅ independently represents a single bond or a divalent linking group. p represents an integer of 1 to 3. When p is 2 or 3, each L₅, each Ry_1; each Ry₂ and each Ry₃ may be the same as or different from every other L₅, Ryi, Ry₂ and Ry₃, respectively.

The alkyl group of Xb may have a substituent, and examples of the substituent include a hydroxyl group and a halogen atom (preferably fluorine atom).

The alkyl group of Xb is preferably an alkyl group having a carbon number of 1 to 4, and examples thereof include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a trifluoromethyl group, with a methyl group being preferred.

Xb is preferably a hydrogen atom or a methyl group.

Specific examples and preferred examples of the alkyl group and cycloalkyl group of Ryi to Ry₃ are the same as specific examples and preferred examples of the alkyl group and cycloalkyl group of Ri_a to R_lc in formula (I).

Specific examples and preferred examples of the ring structure formed by combining two members out of Ryi to Ry₃ are the same as specific examples and preferred examples of the ring structure formed by combining two members out of R to Rj_c in formula (I).

Each of Ryj to Ry₃ is independently, preferably an alkyl group, more preferably a chain or branched alkyl group having a carbon number of 1 to 4. Also, the total of the carbon numbers of the chain or branched alkyl groups as Ry_\ to Ry₃ is preferably 5 or less.

Each of Ryi to Ry₃ may further have a substituent, and examples of the substituent are the same as those of the substituent which Rxi to Rx₃ in formula (AI) may further have.

The linking group having a polycyclic hydrocarbon structure of Z includes a ring- assembly hydrocarbon ring group and a crosslinked cyclic hydrocarbon ring group, and these groups include a group obtained by removing arbitrary (p+1) hydrogen atoms from a ring- assembly hydrocarbon ring and a group obtained by removing arbitrary (p+1) hydrogen atoms from a crosslinked cyclic hydrocarbon ring, respectively.

Examples of the ring-assembly hydrocarbon ring group include a bicyclohexane ring group and a perhydronaphthalene ring group. Examples of the crosslinked cyclic hydrocarbon ring group include a bicyclic hydrocarbon ring group such as pinane ring group, bornane ring group, norpinane ring group, norbornane ring group and bicyclooctane ring group (e.g., bicyclo[2.2.2]octane ring group, bicyclo[3.2.1]octane ring group), a tricyclic hydrocarbon ring group such as homobledane ring group, adamantane ring group,

2 6 2 5

tricyclo[5.2.1.0 ' ]decane ring group and tricyclo[4.3.1.1 ' ]undecane ring group, and a tetracyclic hydrocarbon ring group such as tetracyclo[4.4.0.1²'⁵.l⁷'¹⁰]dodecane ring group and perhydro-l,4-methano-5,8-methanonaphthalene ring group. The crosslinked cyclic hydrocarbon ring group also includes a condensed cyclic hydrocarbon ring group, for example, a condensed ring group formed by fusing a plurality of 5- to 8-membered cycloalkane ring groups, such as perhydronaphthalene (decalin) ring group, perhydroanthracene ring group, perhydrophenathrene ring group, perhydroacenaphthene ring group, perhydrofluorene ring group, perhydroindene ring group and perhydrophenalene ring group.

Preferred examples of the crosslinked cyclic hydrocarbon ring group include a norbornane ring group, an adamantane ring group, a bicyclooctane ring group, and a tricyclo[5,2,l,0²'⁶]decane ring group. Of these crosslinked cyclic hydrocarbon ring groups, a norbornane ring group and an adamantane ring group are more preferred.

The linking group having a polycyclic hydrocarbon structure represented by Z may have a substituent. Examples of the substituent which may be substituted on Z include a substituent such as alkyl group, hydroxyl group, cyano group, keto group (e.g., alkylcarbonyl group), acyloxy group, -COOR, -CON(R)₂, -S0₂R, -S0₃R and -S0₂N(R)₂, wherein R represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.

The alkyl group, alkylcarbonyl group, acyloxy group, -COOR, -CON(R)₂, -S0₂R, - S0₃R and -S0₂N(R)₂ as the substituent which may be substituted on Z may further have a substituent, and this substituent includes a halogen atom (preferably fluorine atom).

In the linking group having a polycyclic hydrocarbon structure represented by Z, the carbon constituting the polycyclic ring (the carbon contributing to ring formation) may be a carbonyl carbon. Also, as described above, the polycyclic ring may have, as a ring member, a heteroatom such as oxygen atom and sulfur atom. However, as described above, Z does not contain an ester bond as an atomic group constituting the polycyclic ring.

Examples of the linking group represented by L₄ and L₅ include -COO-, -OCO-, - CONH-, -NHCO-, -CO-, -0-, -S-, -SO-, -S0₂-, an alkylene group (preferably having a carbon number of 1 to 6), a cycloalkylene group (preferably having a carbon number of 3 to 10), an alkenylene group (preferably having a carbon number of 2 to 6), and a linking group formed by combining a plurality of these members, and a linking group having a total carbon number of 12 or less is preferred.

L₄ is preferably a single bond, an alkylene group, -COO-, -OCO-, -CONH-, -NHCO-, -alkylene group-COO-, -alkylene group-OCO-, -alkylene group-CONH-, -alkylene group- NHCO-, -CO-, -0-, -S0₂- or -alkylene group-O-, more preferably a single bond, an alkylene group, -alkylene group-COO- or -alkylene group-O-.

L₅ is preferably a single bond, an alkylene group, -COO-, -OCO-, -CONH-, -NHCO-, -COO-alkylene group-, -OCO-alkylene group-, -CONH-alkylene group-, -NHCO-alkylene group-, -CO-, -0-, -S0₂-, -O-alkylene group- or -O-cycloalkylene group-, more preferably a single bond, an alkylene group, -COO-alkylene group-, -O-alkylene group- or -O- cycloalkylene group-.

In the descriptions above, the bond "-" at the left end means to be bonded to the ester bond on the main chain side in L₄ and bonded to Z in L₅, and the bond "-" at the right end means to be bonded to Z in L₄ and bonded to the ester bond connected to the group represented by (Ry!)(Ry2)(Ry₃)C- in L₅.

Incidentally, L₄ and L₅ may be bonded to the same atom constituting the polycyclic ring in Z.

p is preferably 1 or 2, more preferably 1.

Specific examples of the repeating unit represented by formula (IV) are illustrated below, but the present invention is not limited thereto. In specific examples, Xa represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom.

The resin (A) may also contain, as the repeating unit having an acid-decomposable group, a repeating unit illustrated below, which is a repeating unit capable of decomposing by the action of an acid to produce an alcoholic hydroxyl group.

In specific examples, Xai represents a hydrogen atom, CH₃, CF₃ or CH₂OH.

As for the repeating unit having an acid-decomposable group, one kind may be used, or two or more kinds may be used in combination.

The content of the acid-decomposable group-containing repeating unit contained in the resin (A) (in the case where a plurality of acid-decomposable group-containing repeating units are present, the total thereof) is preferably from 15 mol% or more, more preferably 20 mol% or more, still more preferably 25 mol% or more, yet still more preferably 50 mol% or more, based on all repeating units in the resin (A). With a content of 50 mol% or more, the local pattern dimension uniformity can be more excellent.

Also, the content of the repeating unit having an acid-decomposable group is preferably 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol% or less, based on all repeating units in the resin (A).

The resin (A) may also contain a repeating unit having a lactone structure or a sultone structure.

As the lactone structure or sultone structure, any structure may be used as long as it has a lactone structure or a sultone structure, but the structure is preferably a 5- to 7-membered ring lactone structure or a 5- to 7-membered ring sultone structure, more preferably a 5- to 7- membered ring lactone structure to which another ring structure is fused in the form of forming a bicyclo or spiro structure, or a 5- to 7-membered ring sultone structure to which another ring structure is fused in the form of forming a bicyclo or spiro structure. The resin more preferably contains a repeating unit having a lactone structure represented by any one of the following formulae (LCl-1) to (LCI -17) or a sultone structure represented by any one of the following formulae (SLl-1) to (SL1-3). The lactone structure or sultone structure may be bonded directly to the main chain. Preferred lactone structures are (LCl-1), (LCI -4), (LC1- 5), (LCl-6), (LCl-13), (LCl-14) and (LCl-17), with (LCl-4) being more preferred. By using such a specific lactone structure, LER and development defect are improved.

S L1-2 SL1-3

SL1-1

The lactone structure moiety or sultone structure moiety may or may not have a substituent (Rb₂). Preferred examples of the substituent (Rb₂) include an alkyl group having a carbon number of 1 to 8, a cycloalkyl group having a carbon number of 4 to 7, an alkoxy group having a carbon number of 1 to 8, an alkoxycarbonyl group having a carbon number of 2 to 8, a carboxyl group, a halogen atom, a hydroxyl group, a cyano group, and an acid- decomposable group. Among these, an alkyl group having a carbon number of 1 to 4, a cyano group and an acid-decomposable group are more preferred. n₂ represents an integer of 0 to 4. When n₂ is an integer of 2 or more, each substituent (Rb₂) may be the same as or different from every other substituent (Rb₂), and also, the plurality of substituents (Rb₂) may combine with each other to form a ring.

The repeating unit having a lactone or sultone structure usually has an optical isomer, and any optical isomer may be used. One optical isomer may be used alone, or a mixture of a plurality of optical isomers may be used. In the case of mainly using one optical isomer, the optical purity (ee) thereof is preferably 90% or more, more preferably 95% or more.

The repeating unit having a lactone or sultone structure is preferably a repeating unit represented b the following formula (III):

In formula (III), A represents an ester bond (a group represented by -COO-) or an amido bond (a group represented by -CONH-).

R₀ represents, when a plurality of R₀ are present, each independently represents, an alkylene group, a cycloalkylene group or a combination thereof.

Z represents, when a plurality of Z are present, each independently represents, a single bond, an ether bond, an ester bond, an amido bond, a urethane bond

O _ _R O

(a group represented by— Q _IL_^ or — U— . Q— )

or a urea bond

(a group represented by — N—^■ ),

wherein each R independently represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.

R₈ represents a monovalent organic group having a lactone structure or a sultone structure.

n is the repetition number of the structure represented by -R₀-Z- and represents an integer of 0 to 5, preferably 0 or 1, more preferably 0. When n is 0, -Ro-Z- is not present, and a single bond is formed.

R₇ represents a hydrogen atom, a halogen atom or an alkyl group.

The alkylene group and cycloalkylene group of R₀ may have a substituent.

Z is preferably an ether bond or an ester bond, more preferably an ester bond.

The alkyl group of R₇ is preferably an alkyl group having a carbon number of 1 to 4, more preferably a methyl group or an ethyl group, still more preferably a methyl group.

The alkyl group in the alkylene group and cycloalkylene group of R₀ and in R₇ may be substituted, and examples of the substituent include a halogen atom such as fluorine atom, chlorine atom and bromine atom, a mercapto group, a hydroxyl group, an alkoxy group such as methoxy group, ethoxy group, isopropoxy group, tert-butoxy group and benzyloxy group, and an acyloxy group such as acetyloxy group and propionyloxy group.

R₇ is preferably a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.

The chain alkylene group in R₀ is preferably a chain alkylene group having a carbon number of 1 to 10, more preferably having a carbon number of 1 to 5, and examples thereof include a methylene group, an ethylene group and a propylene group. The cycloalkylene group is preferably a cycloalkylene group having a carbon number of 3 to 20, and examples thereof include a cyclohexylene group, a cyclopentylene group, a norbornylene group and an adamantylene group. For bringing out the effects of the present invention, a chain alkylene group is more preferred, and a methylene group is still more preferred.

The monovalent organic group having a lactone or sultone structure represented by R₈ is not limited as long as it has a lactone or sultone structure. Specific examples thereof include those having a lactone or sultone structure represented by any one of formulae (LC1- 1) to (LCI -17) and (SLl-1) to (SL1-3), and among these, the structure represented by (LCI -4) is preferred. In (LCl-1) to (LCl-17), n₂ is preferably 2 or less.

R₈ is preferably a monovalent organic group having an unsubstituted lactone or sultone structure, or a monovalent organic group having a lactone or sultone structure containing a methyl group, a cyano group or an alkoxycarbonyl group as a substituent, more preferably a monovalent organic group having a lactone structure containing a cyano group as a substituent (cyanolactone).

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

(In the formulae, Rx represents H, CH₃, CH₂OH or CF₃.)

In order to increase the effects of the present invention, two or more kinds of repeating units having a lactone or sultone structure may be used in combination.

In the case where the resin (A) contains a repeating unit having a lactone or sultone structure, the content of the repeating unit having a lactone or sultone structure is preferably from 5 to 60 mol%, more preferably from 5 to 55 mol%, still more preferably from 10 to 50 mol%, based on all repeating units in the resin (A).

The resin (A) preferably contains a repeating unit having a hydroxyl group or a cyano group, other than the repeating unit represented by formula (III). Thanks to this repeating unit, the adherence to substrate and affinity for developer are enhanced. The repeating unit having a hydroxyl group or a cyano group is preferably a repeating unit having an alicyclic hydrocarbon structure substituted with a hydroxyl group or a cyano group and preferably has no acid-decomposable group. The alicyclic hydrocarbon structure in the alicyclic hydrocarbon structure substituted with a hydroxyl group or a cyano group is preferably an adamantyl group, a diamantyl group or a norbornyl group. The alicyclic hydrocarbon structure substituted with a hydroxyl group or a cyano group is preferably a partial structure represented by the following formulae (Vila) to (Vlld):

(Vila) (Vnb) (VHc) (Vlld)

In formulae (Vila) to (VIIc), each of R₂c to R4C independently represents a hydrogen atom, a hydroxyl group or a cyano group, provided that at least one of R₂c to R4C represents a hydroxyl group or a cyano group. A structure where one or two members out of R₂c to R4C are a hydroxyl group with the remaining being a hydrogen atom is preferred. In formula (Vila), it is more preferred that two members out of R₂c to R4C are a hydroxyl group and the remaining is a hydrogen atom.

The repeating unit having a partial structure represented by formulae (Vila) to (Vlld) includes repeating units represented by the following formulae (Alia) to (Alld):

(AHb)

In formulae (Alia) to (Alld), Ric represents a hydrogen atom, a methyl group, a trifluoromethyl group or a hydroxymethyl group.

R₂c to *c have the same meanings as R₂c to R₄c in formulae (Vila) to (VIIc). In the case where the resin (A) contains a repeating unit having a hydroxyl group or a cyano group, the content of the repeating unit having a hydroxyl group or a cyano group is preferably from 5 to 40 mol%, more preferably from 5 to 30 mol%, still more preferably from 10 to 30 mol%, based on all repeating units in the resin (A).

Specific examples of the repeating unit having a hydroxyl group or a cyano group are illustrated below, but the present invention is not limited thereto.

The resin (A) may contain a repeating unit having an acid group. The acid group includes a carboxyl group, a sulfonamide group, a sulfonylimide group, a bisulfonylimide group, and an aliphatic alcohol substituted with an electron-withdrawing group at the a- position (for example, hexafluoroisopropanol group), and it is preferred to contain a repeating unit having a carboxyl group. By virtue of containing a repeating unit having an acid group, the resolution increases in the usage of forming contact holes. As for the repeating unit having an acid group, all of a repeating unit where an acid group is directly bonded to the main chain of the resin, such as repeating unit by an acrylic acid or a methacrylic acid, a repeating unit where an acid group is bonded to the main chain of the resin through a linking group, and a repeating unit where an acid group is introduced into the polymer chain terminal by using an acid group-containing polymerization initiator or chain transfer agent at the polymerization, are preferred. The linking group may have a monocyclic or polycyclic cyclohydrocarbon structure. In particular, a repeating unit by an acrylic acid or a methacrylic acid is preferred.

The resin (A) may or may not contain a repeating unit having an acid group, but in the case of containing a repeating unit having an acid group, the content thereof is preferably 25 mol% or less, more preferably 20 mol% or less, based on all repeating units in the resin (A). In the case where the resin (A) contains a repeating unit having an acid group, the content of the acid group-containing repeating unit in the resin (A) is usually 1 mol% or more.

Specific examples of the repeating unit having an acid group are illustrated below, but the present invention is not limited thereto.

In specific examples, Rx represents H, CH₃, CH₂OH or CF₃.

The resin (A) for use in the present invention may further contain a repeating unit having an alicyclic hydrocarbon structure free from a polar group (for example, the above- described acid group, a hydroxyl group or a cyano group) and not exhibiting acid decomposability. Thanks to this repeating unit, dissolution of a low molecular component from the resist film to the immersion liquid can be reduced at the immersion exposure and in addition, the solubility of the resin at the development using an organic solvent-containing developer can be appropriately adjusted. Such a repeating unit includes a repeating unit represented by formula (IV):

Ra

(IV)

R. In formula (IV), R₅ represents a hydrocarbon group having at least one cyclic structure and having no polar group.

Ra represents a hydrogen atom, an alkyl group or a -CH₂-0-Ra₂ group, wherein Ra₂ represents a hydrogen atom, an alkyl group or an acyl group. Ra is preferably a hydrogen atom, a methyl group, a hydroxymethyl group or a trifluoromethyl group, more preferably a hydrogen atom or a methyl group.

The cyclic structure contained in R₅ includes a monocyclic hydrocarbon group and a polycyclic hydrocarbon group. Examples of the monocyclic hydrocarbon group include a cycloalkyl group having a carbon number of 3 to 12, such as cyclopentyl group, cyclohexyl group, cycloheptyl group and cyclooctyl group, and a cycloalkenyl group having a carbon number of 3 to 12, such as cyclohexenyl group. The monocyclic hydrocarbon group is preferably a monocyclic hydrocarbon group having a carbon number of 3 to 7, more preferably a cyclopentyl group or a cyclohexyl group.

The polycyclic hydrocarbon group includes a ring-assembly hydrocarbon group and a crosslinked cyclic hydrocarbon group. Examples of the ring-assembly hydrocarbon group include a bicyclohexyl group and a perhydronaphthalenyl group. Examples of the crosslinked cyclic hydrocarbon ring include a bicyclic hydrocarbon ring such as pinane ring, bornane ring, norpinane ring, norbornane ring and bicyclooctane ring (e.g., bicyclo[2.2.2]octane ring, bicyclo [3.2.1] octane ring), a tricyclic hydrocarbon ring such as homobledane ring, adamantane ring, tricyclo[5.2.1.0 ' ]decane ring and tricyclo[4.3.1.1 ' Jundecane ring, and a tetracyclic hydrocarbon ring such as tetracyclo[4.4.0.1²'⁵.l⁷'¹⁰]dodecane ring and perhydro-l ,4-methano-5,8-methanonaphthalene ring. The crosslinked cyclic hydrocarbon ring also includes a condensed cyclic hydrocarbon ring, for example, a condensed ring formed by fusing a plurality of 5- to 8-membered cycloalkane rings, such as perhydronaphthalene (decalin) ring, perhydroanthracene ring, perhydrophenathrene ring, perhydroacenaphthene ring, perhydrofluorene ring, perhydroindene ring and perhydrophenalene ring.

Preferred examples of the crosslinked cyclic hydrocarbon ring include a norbornyl

* 2 6

group, an adamantyl group, a bicyclooctanyl group, and a tricyclo[5,2,l,0 ' Jdecanyl group. Among these crosslinked cyclic hydrocarbon rings, a norbornyl group and an adamantyl group are more preferred.

Such an alicyclic hydrocarbon group may have a substituent, and preferred examples of the substituent include a halogen atom, an alkyl group, a hydroxyl group with a hydrogen atom being substituted for, and an amino group with a hydrogen atom being substituted for. The halogen atom is preferably bromine atom, chlorine atom or fluorine atom, and the alkyl group is preferably a methyl group, an ethyl group, an n-butyl group or a tert-butyl group. This alkyl group may further have a substituent, and the substituent which may be further substituted on the alkyl group includes a halogen atom, an alkyl group, a hydroxyl group with a hydrogen atom being substituted for, and an amino group with a hydrogen atom being substituted for.

Examples of the substituent for the hydrogen atom include an alkyl group, a cycloalkyl group, an aralkyl group, a substituted methyl group, a substituted ethyl group, an alkoxycarbonyl group, and an aralkyloxycarbonyl group. The alkyl group is preferably an alkyl group having a carbon number of 1 to 4; the substituted methyl group is preferably a methoxymethyl group, a methoxythiomethyl group, a benzyloxymethyl group, a tert- butoxymethyl group or a 2-methoxyethoxymethyl group; the substituted ethyl group is preferably a 1 -ethoxy ethyl group or a 1 -methyl- 1-methoxyethyl group; the acyl group is preferably an aliphatic acyl group having a carbon number of 1 to 6, such as formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group and pivaloyl group; and the alkoxycarbonyl group is preferably an alkoxycarbonyl group having a carbon number of 1 to 4.

The resin (A) may or may not contain a repeating unit having an alicyclic hydrocarbon structure free from a polar group and not exhibiting acid decomposability, but in the case of containing this repeating unit, the content thereof is preferably from 1 to 50 mol%, more preferably from 10 to 50 mol%, based on all repeating units in the resin (A).

Specific examples of the repeating unit having an alicyclic hydrocarbon structure free from a polar group and not exhibiting acid decomposability are illustrated below, but the present invention is not limited thereto. In the formulae, Ra represents H, CH₃, CH₂OH or CF₃.

The resin (A) for use in the composition of the present invention may contain, in addition to the above-described repeating structural units, various repeating structural units for the purpose of controlling dry etching resistance, suitability for standard developer, adherence to substrate, resist profile and properties generally required of an actinic ray-sensitive or radiation-sensitive resin composition, such as resolution, heat resistance and sensitivity.

Examples of such a repeating structural unit include, but are not limited to, repeating structural units corresponding to the monomers described below.

Thanks to such a repeating structural unit, the performance required of the resin used in the composition of the present invention, particularly

(1) solubility for the coating solvent,

(2) film-forming property (glass transition temperature),

(3) alkali developability,

(4) film loss (selection of hydrophilic, hydrophobic or alkali-soluble group),

(5) adherence of unexposed area to substrate,

(6) dry etching resistance,

and the like, can be subtly controlled.

Examples of the monomer include a compound having one addition-polymerizable unsaturated bond selected from acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers and vinyl esters.

Other than these compounds, an addition-polymerizable unsaturated compound copolymerizable with the monomers corresponding to the above-described various repeating structural units may be copolymerized.

In the resin (A) for use in the composition of the present invention, the molar ratio of respective repeating structural units contained is appropriately set to control dry etching resistance of the actinic ray-sensitive or radiation-sensitive resin composition, suitability for standard developer, adherence to substrate, resist profile and performances generally required of an actinic ray-sensitive or radiation-sensitive resin composition, such as resolution, heat resistance and sensitivity.

In the case where the composition of the present invention is used for ArF exposure, in view of transparency to ArF light, the resin (A) for Use in the composition of the present invention preferably has substantially no aromatic ring (specifically, the proportion of an aromatic group-containing repeating unit in the resin is preferably 5 mol% or less, more preferably 3 mol% or less, and ideally 0 mol%, that is, not having an aromatic group). The resin (A) preferably has a monocyclic or polycyclic alicyclic hydrocarbon structure.

The form of the resin (A) for use in the present invention may be any of random type, block type, comb type and star type. The resin (A) can be synthesized, for example, by radical, cationic or anionic polymerization of unsaturated monomers corresponding to respective structures. The target resin can be also obtained by polymerizing unsaturated monomers corresponding to precursors of respective structures and then performing a polymer reaction.

In the case where the composition of the present invention contains the later- described resin (D), the resin (A) preferably contains no fluorine atom and no silicon atom in view of compatibility with the resin (D).

The resin (A) for use in the composition of the present invention is preferably a resin where all repeating units are composed of a (meth)acry late-based repeating unit. In this case, all repeating units may be a methacrylate-based repeating unit, all repeating units may be an acrylate-based repeating unit, or all repeating units may be composed of a methacrylate-based repeating unit and an acrylate-based repeating unit, but the content of the acrylate-based repeating unit is preferably 50 mol% or less based on all repeating units.

In the case of irradiating the composition of the present invention with rF excimer laser light, electron beam, X-ray or high-energy beam at a wavelength of 50 nm or less (e.g., EUV), the resin (A) preferably further contains a hydroxystyrene-based repeating unit. It is more preferred to contain a hydroxystyrene-based repeating unit, a hydroxystyrene-based repeating unit protected by an acid-decomposable group, and an acid-decomposable repeating unit such as tertiary alkyl (meth)acrylate.

Preferred examples of the hydroxystyrene-based repeating unit having an acid- decomposable group include repeating units composed of a tert-butoxycarbonyloxystyrene, a 1-alkoxyethoxystyrene and a tertiary alkyl (meth)acrylate. A repeating unit composed of a 2- alkyl-2-adamantyl (meth)acrylate, and a repeating unit composed of a dialkyl(l- adamantyl)methyl (meth)acrylate are more preferred.

The resin (A) for use in the present invention can be synthesized by a conventional method (for example, radical polymerization). Examples of the general synthesis method include a batch polymerization method of dissolving monomer species and an initiator in a solvent and heating the solution, thereby effecting the polymerization, and a dropping polymerization method of adding dropwise a solution containing monomer species and an initiator to a heated solvent over 1 to 10 hours. A dropping polymerization method is preferred. Examples of the reaction solvent include tetrahydrofuran, 1,4-dioxane, ethers such as diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, an ester solvent such as ethyl acetate, an amide solvent such as dimethylformamide and dimethylacetamide, and the later-described solvent capable of dissolving the composition of the present invention, such as propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether and cyclohexanone. The polymerization is more preferably performed using the same solvent as the solvent used in the photosensitive composition of the present invention. By the use of the same solvent, production of particles during storage can be suppressed.

The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As for the polymerization initiator, the polymerization is started using a commercially available radical initiator (e.g., azo-based initiator, peroxide). The radical initiator is preferably an azo-based initiator, and an azo-based initiator having an ester group, a cyano group or a carboxyl group is preferred. Examples of the preferred initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile and dimethyl 2,2'-azobis(2- methylpropionate). The initiator is added additionally or in parts as needed. After the completion of reaction, the reaction solution is poured in a solvent, and the desired polymer is collected by powder, solid or other recovery methods. The concentration at the reaction is from 5 to 50 mass%, preferably from 10 to 30 mass%, and the reaction temperature is usually from 10 to 150°C, preferably from 30 to 120°C, more preferably from 60 to 100°C.

After the completion of reaction, the reaction solution is allowed to cool to room temperature and purified. The purification may be performed by a normal method, for example, a liquid-liquid extraction method of applying water washing or combining it with an appropriate solvent to remove residual monomers or oligomer components; a purification method in a solution sate, such as ultrafiltration of extracting and removing only polymers having a molecular weight not more than a specific value; a reprecipitation method of adding dropwise the resin solution in a poor solvent to solidify the resin in the poor solvent and thereby remove residual monomers and the like; and a purification method in a solid state, such as washing of a resin slurry with a poor solvent after separation of the slurry by filtration.

For example, the resin is precipitated as a solid by contacting the reaction solution with a solvent in which the resin is sparingly soluble or insoluble (poor solvent) and which is in a volumetric amount of 10 times or less, preferably from 10 to 5 times, the reaction solution.

The solvent used at the operation of precipitation or reprecipitation from the polymer solution (precipitation or reprecipitation solvent) may be sufficient if it is a poor solvent for the polymer, and the solvent which can be used may be appropriately selected from, for example, a hydrocarbon, a halogenated hydrocarbon, a nitro compound, an ether, a ketone, an ester, a carbonate, an alcohol, a carboxylic acid, water, and a mixed solvent containing such a solvent, according to the kind of the polymer. Among these solvents, a solvent containing at least an alcohol (particularly, methanol or the like) or water is preferred as the precipitation or reprecipitation solvent.

The amount of the precipitation or reprecipitation solvent used may be appropriately selected by taking into account the efficiency, yield and the like, but in general, the amount used is from 100 to 10,000 parts by mass, preferably from 200 to 2,000 parts by mass, more preferably from 300 to 1,000 parts by mass, per 100 parts by mass of the polymer solution.

The temperature at the precipitation or reprecipitation may be appropriately selected by taking into account the efficiency or operability but is usually on the order of 0 to 50°C, preferably in the vicinity of room temperature (for example, approximately from 20 to 35°C). The precipitation or reprecipitation operation may be performed using a commonly employed mixing vessel such as stirring tank by a known method such as batch system and continuous system.

The precipitated or reprecipitated polymer is usually subjected to commonly employed solid-liquid separation such as filtration and centrifugation, then dried and used. The filtration is performed using a solvent-resistant filter element preferably under pressure. The drying is performed under atmospheric pressure or reduced pressure (preferably under reduced pressure) at a temperature of approximately from 30 to 100°C, preferably on the order of 30 to 50°C.

Incidentally, after the resin is once precipitated and separated, the resin may be again dissolved in a solvent and then put into contact with a solvent in which the resin is sparingly soluble or insoluble. That is, there may be used a method comprising, after the completion of radical polymerization reaction, bringing the polymer into contact with a solvent in which the polymer is sparingly soluble or insoluble, to precipitate a resin (step a), separating the resin from the solution (step b), anew dissolving the resin in a solvent to prepare a resin solution A (step c), bringing the resin solution A into contact with a solvent in which the resin is sparingly soluble or insoluble and which is in a volumetric amount of less than 10 times (preferably 5 times or less) the resin solution A, to precipitate a resin solid (step d), and separating the precipitated resin (step e).

Also, for keeping the resin from aggregation or the like after preparation of the composition, as described, for example, in JP-A-2009-037108, a step of dissolving the synthesized resin in a solvent to make a solution and heating the solution at approximately from 30 to 90°C for approximately from 30 minutes to 4 hours may be added.

The weight average molecular weight of the resin (A) for use in the present invention is, as described above, 7,000 or more, preferably from 7,000 to 200,000, more preferably from 7,000 to 50,000, still more preferably from 7,000 to 40,000, yet still more preferably from 7,000 to 30,000, in terms of polystyrene by the GPC method. If the weight average molecular weight is less than 7,000, solubility for an organic solvent becomes too high and a precise pattern may not be formed.

The polydispersity (molecular weight distribution) is usually from 1.0 to 3.0, preferably from 1.0 to 2.6, more preferably from 1.0 to 2.0, still more preferably from 1.4 to 2.0. As the molecular weight distribution is smaller, not only the resolution and resist profile are more excellent but also the side wall of the resist pattern is smoother and the roughness is more improved.

In the actinic ray-sensitive or radiation-sensitive resin composition of the present invention, the blending ratio of the resin (A) in the entire composition is preferably from 30 to 99 mass%, more preferably from 60 to 95 mass%, based on the total solid content. (In this specification, mass ratio is equal to weight ratio.) In the present invention, as for the resin (A), one kind of a resin may be used or a plurality of kinds of resins may be used in combination.

[2] (C) Resin different from the resin (A) and capable of increasing the polarity by an action of an acid to decrease the solubility for an organic solvent-containing developer

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may contain (C) an acid-decomposable resin different from the resin (A).

The resin (C) has an acid-decomposable group described for the resin (A) and preferably contains a repeating unit having an acid-decomposable group described for the resin (A).

The resin (C) may contain a repeating unit other than the repeating unit having an acid-decomposable group, which is described for the resin (A).

However, the resin (C) does not have (I) a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity.

The actinic ray-sensitive or radiation-sensitive resin composition may or may not contain the resin (C), but in the case of containing the resin, the content thereof is preferably from 1 to 95 mass%, more preferably from 1 to 70 mass%, still more preferably from 1 to 30 mass%, yet still more preferably from 1 to 10 mass%, based on the total solid content of the composition.

In view of the pre-bridge dimension performance, the actinic ray-sensitive or radiation-sensitive resin composition of the present invention preferably does not contain the resin (C) as the resin capable of increasing polarity by the action of an acid to decrease the solubility for an organic solvent-containing developer, that is, preferably contains only the resin (A).

[3] (B) Compound capable of generating an acid upon irradiation with an actinic ray or radiation

The composition for use in the present invention further contains (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation (hereinafter, sometimes referred to as "acid generator"). The compound (B) capable of generating an acid upon irradiation with an actinic ray or radiation is preferably a compound capable of generating an organic acid upon irradiation with an actinic ray or radiation.

The acid generator which can be used may be appropriately selected from a photo- initiator for cationic photopolymerization, a photo-initiator for radical photopolymerization, a photo-decoloring agent for dyes, a photo-discoloring agent, a known compound capable of generating an acid upon irradiation with an actinic ray or radiation, which is used for a microresist or the like, and a mixture thereof.

Examples thereof include a diazonium salt, a phosphonium salt, a sulfonium salt, an iodonium salt, imidosulfonate, oxime sulfonate, diazodisulfone, disulfone, and o-nitrobenzyl sulfonate.

Out of acid generators, preferred compounds include compounds represented by the following formulae (ZI), (ZII) and (ZIII):

In formula (ZI), each of R₂₀i, R₂₀₂ and R₂₀₃ independently represents an organic group.

The carbon number of the organic group as R₂₀₁, R₂₀₂ and R₂₀₃ is generally from 1 to 30, preferably from 1 to 20.

Two members out of R₂₀₁ to R₂₀₃ may combine to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond or a carbonyl group. Examples of the group formed by combining two members out of R₂₀i to R₂₀₃ include an alkylene group (e.g., butylene, pentylene).

Z^" represents a non-nucleophilic anion.

Examples of the non-nucleophilic anion as Z^" include sulfonate anion, carboxylate anion, sulfonylimide anion, bis(alkylsulfonyl)imide anion, and tris(alkylsulfonyl)methyl anion.

The non-nucleophilic anion is an anion having an extremely low ability of causing a nucleophilic reaction, and this anion can suppress the decomposition with aging due to an intramolecular nucleophilic reaction. Thanks to this anion, the aging stability of the resist composition is improved.

Examples of the sulfonate anion include an aliphatic sulfonate anion, an aromatic sulfonate anion, and a camphorsulfonate 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 and aliphatic carboxylate may be an alkyl group or a cycloalkyl group but is preferably an alkyl group having a carbon number of 1 to 30 or a cycloalkyl group having a carbon number of 3 to 30, and examples thereof include 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, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornyl group, and a bornyl group.

The aromatic group in the aromatic sulfonate anion and aromatic carboxylate anion is preferably an aryl group having a carbon number of 6 to 14, and examples thereof include a phenyl group, a tolyl group and a naphthyl group.

The alkyl group, cycloalkyl group and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion may have a substituent. Examples of the substituent on the alkyl group, cycloalkyl group and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion include a nitro group, a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), a carboxyl group, a hydroxyl group, an amino group, a cyano group, an alkoxy group (preferably having a carbon number of 1 to 15), a cycloalkyl group (preferably having a carbon number of 3 to 15), an aryl group (preferably having a carbon number of 6 to 14), an alkoxycarbonyl group (preferably having a carbon number of 2 to 7), an acyl group (preferably having a carbon number of 2 to 12), an alkoxycarbonyloxy group (preferably having a carbon number of 2 to 7), an alkylthio group (preferably having a carbon number of 1 to 15), an alkylsulfonyl group (preferably having a carbon number of 1 to 15), an alkyliminosulfonyl group (preferably having a carbon number of 1 to 15), an aryloxysulfonyl group (preferably having a carbon number of 6 to 20), an alkylaryloxysulfonyl group (preferably having a carbon number of 7 to 20), a cycloalkylaryloxysulfonyl group (preferably having a carbon number of 10 to 20), an alkyloxyalkyloxy group (preferably having a carbon number of 5 to 20), and a cycloalkylalkyloxyalkyloxy group (preferably having a carbon number of 8 to 20). The aryl group and ring structure in each group may further have, as a substituent, an alkyl group (preferably having a carbon number of 1 to 15) or a cycloalkyl group (preferably having a carbon number of 3 to 15).

The aralkyl group in the aralkylcarboxylate anion is preferably an aralkyl group having a carbon number of 7 to 12, and examples thereof include a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, and a naphthylbutyl group.

The alkyl group, cycloalkyl group, aryl group and aralkyl group in the aliphatic carboxylate anion, aromatic carboxylate anion and aralkylcarboxylate anion may have a substituent. Examples of the substituent include the same halogen atom, alkyl group, cycloalkyl group, alkoxy group and alkylthio group as those in the aromatic sulfonate anion.

Examples of the sulfonylimide anion include saccharin anion.

The alkyl group in the bis(alkylsulfonyl)imide anion and tris(alkylsulfonyl)methide anion is preferably an alkyl group having a carbon number of 1 to 5, and examples thereof include 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, and a neopentyl group.

Two alkyl groups in the bis(alkylsulfonyl)imide anion may combine to make an alkylene group (preferably having a carbon number of 2 to 4) and form a ring together with the imide group and two sulfonyl groups. Examples of the substituent which may be substituted on the alkyl group and the alkylene group formed by combining two alkyl groups in the bis(alkylsulfonyl)imide anion, include a halogen atom, a halogen atom-substituted alkyl group, an alkoxy group, an alkylthio group, an alkyloxysulfonyl group, an aryloxysulfonyl group, and a cycloalkylaryloxysulfonyl group, with a fluorine atom-substituted alkyl group being preferred.

Other examples of the non-nucleophilic anion include fluorinated phosphorus (e.g., PF₆ ^~), fluorinated boron (e.g., BF₄ ^"), and fluorinated antimony (e.g., SbF₆ ^")-

The non-nucleophilic anion of Z^" is preferably an aliphatic sulfonate anion substituted with a fluorine atom at least at the a-position of sulfonic acid, an aromatic sulfonate anion substituted with a fluorine atom or a fluorine atom-containing group, a bis(alkylsulfonyl)imide anion in which the alkyl group is substituted with a fluorine atom, or a tris(alkylsulfonyl)methide anion in which the alkyl group is substituted with a fluorine atom. The non-nucleophilic anion is more preferably a perfluoroaliphatic sulfonate anion having a carbon number of 4 to 8 or a benzenesulfonate anion having a fluorine atom, still more preferably nonafluorobutanesulfonate anion, perfluorooctanesulfonate anion, pentafluorobenzenesulfonate anion or 3,5-bis(trifluoromethyl)benzenesulfonate anion.

The acid generator is preferably a compound capable of generating an acid represented by the following formula (V) or (VI) upon irradiation with an actinic ray or radiation. The compound capable of generating an acid represented by the following formula (V) or (VI) has a cyclic organic group, so that the resolution and roughness performance can be more improved.

The non-nucleophilic anion described above can be an anion capable of producing an organic acid represented by the following formula (V) or (VI):

(V) (VI)

In the formulae, each Xf independently represents a fluorine atom or an alkyl group substituted with at least one fluorine atom.

Each of Ru and R₁₂ independently represents a hydrogen atom, a fluorine atom or an alkyl group.

Each L independently represents a divalent linking group.

Cy represents a cyclic organic group.

Rf represents a fluorine atom-containing group.

x represents an integer of 1 to 20.

y represents an integer of 0 to 10.

z represents an integer of 0 to 10.

Xf represents a fluorine atom or an alkyl group substituted with at least one fluorine atom. The carbon number of the alkyl group is preferably from 1 to 10, more preferably from 1 to 4. Also, the alkyl group substituted with at least one fluorine atom is preferably a perfluoroalkyl group.

Xf is preferably a fluorine atom or a perfluoroalkyl group having a carbon number of 1 to 4. Specifically, Xf is preferably a fluorine atom, CF₃, C₂F₅, C₃F₇, C₄F₉, C5F 1 1 , C₆F[₃, C₇F₁₅, C₈Fi_7, CH₂CF₃, CH₂C¾CF₃, CH₂C₂F₅, CH₂CH₂C₂F₅, CH₂C₃F₇, CH₂CH₂C₃F₇, CH₂C₄F₉ or CH₂CH₂C₄F₉, more preferably a fluorine atom or CF₃, and it is still more preferred that both Xf are a fluorine atom.

Each of Ru and R]₂ independently represents a hydrogen atom, a fluorine atom or an alkyl group. The alkyl group may have a substituent (preferably fluorine atom) and is preferably an alkyl group having a carbon number of 1 to 4, more preferably a perfluoroalkyl group having a carbon number of 1 to 4. Specific examples of the alkyl group having a substituent of Ru and R,₂ include CF₃, C₂F₅, C₃F₇, C₄F₉, C₅F„, C₆F₁₃, C₇F₁₅, C₈F₁₇, CH₂CF₃, CH₂CH₂CF₃, CH₂C₂F₅, CH₂CH₂C₂F₅, CH₂C₃F₇, CH₂CH₂C₃F₇, CH₂C₄F₉ and CH₂CH₂C₄F₉, with CF₃ being preferred.

L represents a divalent linking group. Examples of the divalent linking group include -COO-, -OCO-, -CONH-, -NHCO-, -CO-, -0-, -S-, -SO-, -S0₂-, an alkylene group (preferably having a carbon number of 1 to 6), a cycloalkylene group (preferably having a carbon number of 3 to 10), an alkenylene group (preferably having a carbon number of 2 to 6), and a divalent linking group formed by combining a plurality of these members. Among these, -COO-, -OCO-, -CONH-, -NHCO-, -CO-, -0-, -S0₂-, -COO-alkylene group-, -OCO- alkylene group-, -CONH-alkylene group- and -NHCO-alkylene group- are preferred, and - COO-, -OCO-, -CONH-, -S0₂-, -COO-alkylene group- and -OCO-alkylene group- are more preferred.

Cy represents a cyclic organic group. Examples of the cyclic organic group include an alicyclic group, an aryl group, and a heterocyclic group

The alicyclic group may be monocyclic or polycyclic. The monocyclic alicyclic group includes, for example, a monocyclic cycloalkyl group such as cyclopentyl group, cylohexyl group and cyclooctyl group. The polycyclic alicyclic group includes, for example, a polycyclic cycloalkyl group such as norbornyl group, tricyclodecanyl group, tetracyclodecanyl group, tetracyclododecanyl group and adamantyl group. Above all, an alicyclic group having a bulky structure with a carbon number of 7 or more, such as norbornyl group, tricyclodecanyl group, tetracyclodecanyl group, tetracyclododecanyl group and adamantyl group, is preferred from the standpoint of suppressing diffusion in film at the PEB (post-exposure baking) step and improving MEEF (Mask Error Enhancement Factor).

The aryl group may be monocyclic or polycyclic. Examples of the aryl group include a phenyl group, a naphthyl group, a phenanthryl group, and an anthryl group. Among these, a naphthyl group is preferred because of its relatively low light absorbance at 193 nm.

The heterocyclic group may be monocyclic or polycyclic, but a polycyclic heterocyclic group can more suppress diffusion of an acid. The heterocyclic group may have aromaticity or may not have aromaticity. Examples of the heterocyclic ring having aromaticity include a furan ring, a thiophene ring, a benzofuran ring, a benzothiophene ring, a dibenzofuran ring, a dibenzothiophene ring, and a pyridine ring. Examples of the heterocyclic ring not having aromaticity include a tetrahydropyran ring, a lactone ring, a sultone ring, and a decahydroisoquinoline ring. The heterocyclic ring in the heterocyclic group is preferably a furan ring, a thiophene ring, a pyridine ring or a decahydroisoquinoline ring. Examples of the lactone ring or sultone ring include lactone structures or sultone structures recited for the resin (A) above.

The above-described cyclic organic group may have a substituent, and examples of the substituent include an alkyl group (may be linear or branched, preferably having a carbon number of 1 to 12), a cycloalkyl group (may be monocyclic, polycyclic or spirocyclic, preferably having a carbon number of 3 to 20), an aryl group (preferably having a carbon number of 6 to 14), a hydroxyl group, an alkoxy group, an ester group, an amido group, a urethane group, a ureido group, a thioether group, a sulfonamido group, and a sulfonic acid ester group. Incidentally, the carbon constituting the cyclic organic group (the carbon contributing to ring formation) may be a carbonyl carbon.

x is preferably from 1 to 8, more preferably from 1 to 4, still more preferably 1. y is preferably from 0 to 4, more preferably 0. z is preferably from 0 to 8, more preferably from 0 to 4.

The fluorine atom-containing group represented by Rf includes, for example, an alkyl group having at least one fluorine atom, a cycloalkyl group having at least one fluorine atom, and an aryl group having at least one fluorine atom.

These alkyl, cycloalkyl and aryl groups may be substituted with a fluorine atom or may be substituted with another fluorine atom-containing substituent. In the case where Rf is a cycloalkyl group having at least one fluorine atom or an aryl group having at least one fluorine atom, the another fluorine-containing substituent includes, for example, an alkyl group substituted with at least one fluorine atom.

Also, these alkyl, cycloalkyl and aryl groups may be further substituted with a fluorine atom-free substituent. Examples of this substituent include those not containing a fluorine atom out of the groups described above for Cy.

Examples of the alkyl group having at least one fluorine atom represented by Rf are the same as those described above as the alkyl group substituted with at least one fluorine atom represented by Xf. Examples of the cycloalkyl group having at least one fluorine atom represented by Rf include a perfluorocyclopentyl group and a perfluorocyclohexyl group. Examples of the aryl group having at least one fluorine atom represented by Rf include a perfluorophenyl group.

The organic group represented by R₂₀i, R202 and R₂₀3 includes, for example, corresponding groups in the later-described compounds (ZI-1), (ZI-2), (ZI-3) and (ZI-4). The compound may be a compound having a plurality of structures represented by formula (ZI). For example, the compound may be a compound having a structure where at least one of R₂₀₁ to R₂₀₃ in a compound represented by formula (ZI) is bonded to at least one of R₂₀i to R₂₀₃ in another compound represented by formula (ZI) through a single bond or a linking group.

Compounds (ZI-1), (ZI-2), (ZI-3) and (ZI-4) described below are more preferred as the component (ZI).

The compound (ZI-1) is an arylsulfonium compound where at least one of R₂₀₁ to R₂₀₃ in formula (ZI) is an aryl group, that is, a compound having an arylsulfonium as the cation.

In the arylsulfonium compound, all of R₂₀i to R₂₀₃ may be an aryl group, or a part of R₂₀₁ to R₂₀₃ may be an aryl group, with the remaining being an alkyl group or a cycloalkyl group.

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

The aryl group in the arylsulfonium compound is preferably a phenyl group or a naphthyl group, more preferably a phenyl group. The aryl group may be an aryl group having a heterocyclic structure containing an oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of the heterocyclic structure include a pyrrole residue, a furan residue, a thiophene residue, an indole residue, a benzofuran residue, and a benzothiophene residue. In the case where the arylsulfonium compound has two or more aryl groups, these two or more aryl groups may be the same or different.

The alkyl or cycloalkyl group which is contained, if desired, in the arylsulfonium compound is preferably a linear or branched alkyl group having a carbon number of 1 to 15 or a cycloalkyl group having a carbon number of 3 to 15, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.

The aryl group, alkyl group and cycloalkyl group of R₂₀₁ to R₂₀₃ may have, as a substituent, an alkyl group (for example, having a carbon number of 1 to 15), a cycloalkyl group (for example, having a carbon number of 3 to 15), an aryl group (for example, having a carbon number of 6 to 14), an alkoxy group (for example, having a carbon number of 1 to 15), a halogen atom, a hydroxyl group or a phenylthio group. The substituent is preferably a linear or branched alkyl group having a carbon number of 1 to 12, a cycloalkyl group having a carbon number of 3 to 12, or a linear, branched or cyclic alkoxy group having a carbon number of 1 to 12, more preferably an alkyl group having a carbon number of 1 to 4, or an alkoxy group having a carbon number of 1 to 4. The substituent may be substituted on any one of three members R₂₀₁ to R₂₀₃ or may be substituted on all of these three members. In the case where R₂oi to R₂₀₃ are an aryl group, the substituent is preferably substituted on the p- position of the aryl group.

The compound (ZI-2) is described below.

The compound (ZI-2) is a compound where each of R₂₀₁ to R₂₀₃ in formula (ZI) independently represents an aromatic ring-free organic group. The aromatic ring as used herein encompasses an aromatic ring containing a heteroatom.

The aromatic ring-free organic group as R₂₀i to R₂₀₃ has a carbon number of generally from 1 to 30, preferably from 1 to 20.

Each of R₂₀₁ to R₂₀₃ is independently, preferably an alkyl group, a cycloalkyl group, an allyl group or a vinyl group, more preferably a linear or branched 2-oxoalkyl group, a 2- oxocycloalkyl group or an alkoxycarbonylmethyl group, still more preferably a linear or branched 2-oxoalkyl group.

The alkyl group and cycloalkyl group of R₂₀i to R₂₀₃ are preferably a linear or branched alkyl group having a carbon number of 1 to 10 (e.g., methyl, ethyl, propyl, butyl, pentyl) and a cycloalkyl group having a carbon number of 3 to 10 (e.g., cyclopentyl, cyclohexyl, norbornyl). The alkyl group is more preferably a 2-oxoalkyl group or an alkoxycarbonylmethyl group. The cycloalkyl group is more preferably a 2-oxocycloalkyl group.

The 2-oxoalkyl group may be either linear or branched and is preferably a group having >C=0 at the 2-position of the above-described alkyl group.

The 2-oxocycloalkyl group is preferably a group having >C=0 at the 2-position of the above-described cycloalkyl group.

The alkoxy group in the alkoxycarbonylmethyl group is preferably an alkoxy group having a carbon number of 1 to 5 (e.g., methoxy, ethoxy, propoxy, butoxy, pentoxy).

R₂₀₁ to R₂₀₃ may be further substituted with a halogen atom, an alkoxy group (for example, having a carbon number of 1 to 5), a hydroxyl group, a cyano group or a nitro group.

The compound (ZI-3) is described below.

The compound (ZI-3) is a compound represented by the following formula (ZI-3), and this is a com ound having a henacylsulfonium salt structure

In formula (ZI-3), each of Ri_c to R_5c independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an alkylcarbonyloxy group, a cycloalkylcarbonyloxy group, a halogen atom, a hydroxyl group, a nitro group, an alkylthio group or an arylthio group.

Each of R_6c and R_7c independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an aryl group.

Each of R_x and R_y independently represents an alkyl group, a cycloalkyl group, a 2- oxoalkyl group, a 2-oxocycloalkyl group, an alkoxycarbonylalkyl group, an allyl group or a vinyl group.

Any two or more members out of R]_C to R_5c, a pair of R_5c and R_6c, a pair of R_6c and R_7c, a pair of R_5c and R_x, or a pair of R_x and R_y may combine together to form a ring structure. This ring structure may contain an oxygen atom, a sulfur atom, a ketone group, an ester bond or an amide bond.

The ring structure above includes an aromatic or non-aromatic hydrocarbon ring, an aromatic or non-aromatic heterocyclic ring, and a polycyclic condensed ring formed by combining two or more of these rings. The ring structure includes a 3- to 10-membered ring and is preferably a 4- to 8-membered ring, more preferably a 5- or 6-membered ring.

Examples of the group formed by combining any two or more members out of R)_C to R_5c, a pair of R^ and R_7c, or a pair of R_x and R_y include a butylene group and a pentylene group.

The group formed by combining a pair of R_5c and R_6c or a pair of R_5c and R_x is preferably a single bond or an alkylene group, and examples of the alkylene group include a methylene group and an ethylene group.

Zc^" represents a non-nucleophilic anion, and examples thereof are the same as those of the non-nucleophilic anion of Z^" in formula (ZI).

The alkyl group as R_lc to R_7c may be either linear or branched and is, for example, an alkyl group having a carbon number of 1 to 20, preferably a linear or branched alkyl group having a carbon number of 1 to 12 (such as methyl group, ethyl group, linear or branched propyl group, linear or branched butyl group, or linear or branched pentyl group). The cycloalkyl group is, for example, a cycloalkyl group having a carbon number of 3 to 10 (such as cyclopentyl group or cyclohexyl group).

The aryl group as Rj_c to R_5c is preferably an aryl group having a carbon number of 5 to 15, and examples thereof include a phenyl group and a naphthyl group.

The alkoxy group as R_lc to R_5c may be linear, branched or cyclic and is, for example, an alkoxy group having a carbon number of 1 to 10, preferably a linear or branched alkoxy group having a carbon number of 1 to 5 (such as methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, or linear or branched pentoxy group), or a cyclic alkoxy group having a carbon number of 3 to 10 (such as cyclopentyloxy group or cyclohexyloxy group).

Specific examples of the alkoxy group in the alkoxycarbonyl group as R_lc to R_5c are the same as specific examples of the alkoxy group of Rj_c to R_5c.

Specific examples of the alkyl group in the alkylcarbonyloxy group and alkylthio group as R]_C to R_5c are the same as specific examples of the alkyl group of R_lc to R_5c.

Specific examples of the cycloalkyl group in the cycloalkylcarbonyloxy group as Ri_c to R_5c are the same as specific examples of the cycloalkyl group of Rj_c to R_5c.

Specific examples of the aryl group in the aryloxy group and arylthio group as Ri_c to R_5c are the same as specific examples of the aryl group of R_lc to R_5c.

A compound where any one of Rj_c to R_5c is a linear or branched alkyl group, a cycloalkyl group or a linear, branched or cyclic alkoxy group is preferred, and a compound where the sum of carbon numbers of Ri_c to R_5c is from 2 to 15 is more preferred. Thanks to such a compound, the solvent solubility is more enhanced, and production of particles during storage can be suppressed.

The ring structure which may be formed by combining any two or more members out of Ric to R_5c with each other is preferably a 5- or 6-membered ring, more preferably a 6- membered ring (such as phenyl ring).

The ring structure which may be formed by combining R_5c and R_6c with each other includes a 4-membered or higher membered ring (preferably a 5- or 6-membered ring) formed together with the carbonyl carbon atom and carbon atom in formula (I) by combining R_5c and R_6c with each other to constitute a single bond or an alkylene group (such as methylene group or ethylene group).

The aryl group as R6_C and R_7c is preferably an aryl group having a carbon number of 5 to 15, and examples thereof include a phenyl group and a naphthyl group.

An embodiment where both of R_6c and R_7c are an alkyl group is preferred, an embodiment where each of R_6c and R_7c is a linear or branched alkyl group having a carbon number of 1 to 4 is more preferred, and an embodiment where both are a methyl group is still more preferred.

In the case where R_6c and R_7c are combined to form a ring, the group formed by combining R _c and R _c is preferably an alkylene group having a carbon number of 2 to 10, and examples thereof include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. Also, the ring formed by combining R_6c and R_7c may contain a heteroatom such as oxygen atom in the ring.

Examples of the alkyl group and cycloalkyl group as R_x and R_y are the same as those of the alkyl group and cycloalkyl group of R_lc to R_7c.

Examples of the 2-oxoalkyl group and 2-oxocycloalkyl group as R_x and R_y include a group having >C=0 at the 2-position of the alkyl group or cycloalkyl group of R]_C to R_7c.

Examples of the alkoxy group in the alkoxycarbonylalkyl group as R_x and R_y are the same as those of the alkoxy group of Ri_c to R_5c. The alkyl group is, for example, an alkyl group having a carbon number of 1 to 12, preferably a linear alkyl group having a carbon number of 1 to 5 (such as methyl group or ethyl group).

The allyl group as R_x and R_y is not particularly limited but is preferably an unsubstituted allyl group or an allyl group substituted with a monocyclic or polycyclic cycloalkyl group (preferably a cycloalkyl group having a carbon number of 3 to 10).

The vinyl group as R_x and R_y is not particularly limited but is preferably an unsubstituted vinyl group or a vinyl group substituted with a monocyclic or polycyclic cycloalkyl group (preferably a cycloalkyl group having a carbon number of 3 to 10).

The ring structure which may be formed by combining R_5c and R_x with each other includes a 5-membered or higher membered ring (preferably a 5-membered ring) formed together with the sulfur atom and carbonyl carbon atom in formula (I) by combining R_5c and R_x with each other to constitute a single bond or an alkylene group (such as methylene group or ethylene group).

The ring structure which may be formed by combining R_x and R_y with each other includes a 5- or 6-membered ring, preferably a 5-membered ring (that is, tetrahydrothiophene ring), formed by divalent R_x and R_y (for example, a methylene group, an ethylene group or a propylene group) together with the sulfur atom in formula (ZI-3).

Each of R_x and R_y is preferably an alkyl or cycloalkyl group having a carbon number of 4 or more, more preferably 6 or more, still more preferably 8 or more.

Each of R_lc to R_7c, R_x and R_y may further have a substituent, and examples of such a substituent include a halogen atom (e.g., fluorine atom), a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an arylcarbonyl group, an alkoxyalkyl group, an aryloxyalkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkoxycarbonyloxy group, and an aryloxycarbonyloxy group.

In formula (ZI-3), it is more preferred that each of Ri_c, R_2c, R4_C and R_5c independently represents a hydrogen atom and R_3c represents a group except for a hydrogen atom, that is, represents an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an alkylcarbonyloxy group, a cycloalkylcarbonyloxy group, a halogen atom, a hydroxyl group, a nitro group, an alkylthio group or an arylthio group.

Specific examples of the cation in the compound represented by formula (ZI-2) or (ZI-3) for use in the present invention are illustrated below.

The compound (ZI-4) is described below.

The compound (ZI-4) is represented by the following formula (ZI-4):

In formula (ZI-4), Ri₃ represents a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group or a group having a cycloalkyl group. These groups may have a substituent.

R₁₄ represents, when a plurality of Rj₄ are present, each independently represents, a hydroxyl group, an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group, an alkylcarbonyl group, an alkylsulfonyl group, a cycloalkylsulfonyl group or a group having a cycloalkyl group. These groups may have a substituent.

Each Ri₅ independently represents an alkyl group, a cycloalkyl group or a naphthyl group. Two R₁₅ may combine with each other to form a ring. These groups may have a substituent.

1 represents an integer of 0 to 2.

r represents an integer of 0 to 8.

Z^" represents a non-nucleophilic anion, and examples thereof are the same as those of the nucleophilic anion of Z^" in formula (ZI).

In formula (ZI-4), the alkyl group of R]₃, R₁₄ and Ri₅ is a linear or branched alkyl group preferably having a carbon number of 1 to 10, and preferred examples thereof include a methyl group, an ethyl group, an n-butyl group, and a tert-butyl group.

The cycloalkyl group of Ri₃, R₁₄ and R]₅ includes a monocyclic or polycyclic cycloalkyl group (preferably a cycloalkyl group having a carbon number of 3 to 20) and, among others, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl are preferred.

The alkoxy group of Rn and Rj₄ is a linear or branched alkoxy group preferably having a carbon number of 1 to 10, and preferred examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group.

The alkoxycarbonyl group of R_]3 and R₁₄ is a linear or branched alkoxycarbonyl group preferably having a carbon number of 2 to 1 1, and preferred examples thereof include a methoxycarbonyl group, an ethoxycarbonyl group, and an n-butoxycarbonyl group.

The group having a cycloalkyl group of R₁₃ and Rj₄ includes a monocyclic or polycyclic cycloalkyl group (preferably a cycloalkyl group having a carbon number of 3 to 20), and examples thereof include a monocyclic or polycyclic cycloalkyloxy group and an alkoxy group having a monocyclic or polycyclic cycloalkyl group. These groups may further have a substituent.

The monocyclic or polycyclic cycloalkyloxy group of Ri₃ and Ri₄ preferably has a total carbon number of 7 or more, more preferably a total carbon number of 7 to 15, and it is preferred to have a monocyclic cycloalkyl group. The monocyclic cycloalkyloxy group having a total carbon number of 7 or more indicates a monocyclic cycloalkyloxy group where a cycloalkyloxy group such as cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, cyclooctyloxy group and cyclododecanyloxy group arbitrarily has a substituent such as alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, dodecyl group, 2-ethylhexyl group, isopropyl group, sec-butyl group, tert-butyl group, isoamyl group), hydroxyl group, halogen atom (e.g., fluorine, chlorine, bromine, iodine), nitro group, cyano group, amido group, sulfonamido group, alkoxy group (e.g., methoxy group, ethoxy group, hydroxyethoxy group, propoxy group, hydroxypropoxy group, butoxy group), alkoxycarbonyl group (e.g., methoxycarbonyl group, ethoxycarbonyl group), acyl group (e.g., formyl group, acetyl group, benzoyl group), acyloxy group (e.g., acetoxy group, butyryloxy group) and carboxy group and where the total carbon number inclusive of the carbon number of an arbitrary substituent on the cycloalkyl group is 7 or more.

Examples of the polycyclic cycloalkyloxy group having a total carbon number of 7 or more include a norbornyloxy group, a tricyclodecanyloxy group, a tetracyclodecanyloxy group, and an adamantyloxy group.

The alkoxy group having a monocyclic or polycyclic cycloalkyl group of R13 and Ri4 preferably has a total carbon number of 7 or more, more preferably a total carbon number of 7 to 15, and is preferably an alkoxy group having a monocyclic cycloalkyl group. The alkoxy group having a total carbon number of 7 or more and having a monocyclic cycloalkyl group indicates an alkoxy group where the above-described monocyclic cycloalkyl group which may have a substituent is substituted on an alkoxy group such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptoxy, octyloxy, dodecyloxy, 2-ethylhexyloxy, isopropoxy, sec-butoxy, tert-butoxy and isoamyloxy and where the total carbon number inclusive of the carbon number of the substituent is 7 or more. Examples thereof include a cyclohexylmethoxy group, a cyclopentylethoxy group, and a cyclohexylethoxy group, with a cyclohexylmethoxy group being preferred.

Examples of the alkoxy group having a total carbon number of 7 or more and having a polycyclic cycloalkyl group include a norbornylmethoxy group, a norbornylethoxy group, a tricyclodecanylmethoxy group, a tricyclodecanylethoxy group, a tetracyclodecanylmethoxy group, a tetracyclodecanylethoxy group, an adamantylmethoxy group, and an adamantylethoxy group, with a norbornylmethoxy group and a norbornylethoxy group being preferred.

Specific examples of the alkyl group in the alkylcarbonyl group of R₁₄ are the same as those of the alkyl group of R]₃ to R₁₅.

The alkylsulfonyl or cycloalkylsulfonyl group of Ri₄ is a linear, branched or cyclic alkylsulfonyl group preferably having a carbon number of 1 to 10, and preferred examples thereof include a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, a cyclopentanesulfonyl group, and a cyclohexanesulfonyl group.

Examples of the substituent which each of the groups above may have include a halogen atom (e.g., fluorine atom), a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkoxy group, an alkoxyalkyl group, an alkoxycarbonyl group, and an alkoxycarbonyloxy group.

Examples of the alkoxy group include a linear, branched or cyclic alkoxy group having a carbon number of 1 to 20, such as methoxy group, ethoxy group, n-propoxy group, i- propoxy group, n-butoxy group, 2-methylpropoxy group, 1-methylpropoxy group, tert-butoxy group, cyclopentyloxy group and cyclohexyloxy group.

Examples of the alkoxyalkyl group include a linear, branched or cyclic alkoxyalkyl group having a carbon number of 2 to 21, such as methoxymethyl group, ethoxymethyl group, 1-methoxyethyl group, 2-methoxyethyl group, 1-ethoxyethyl group and 2-ethoxyethyl group.

Examples of the alkoxycarbonyl group include a linear, branched or cyclic alkoxycarbonyl group having a carbon number of 2 to 21, such as methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, i-propoxycarbonyl group, n-butoxycarbonyl group, 2-methylpropoxycarbonyl group, 1 -methylpropoxycarbonyl group, tert-butoxycarbonyl group, cyclopentyloxycarbonyl group and cyclohexyloxycarbonyl group.

Examples of the alkoxycarbonyloxy group include a linear, branched or cyclic alkoxycarbonyloxy group having a carbon number of 2 to 21, such as methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propoxycarbonyloxy group, i-propoxycarbonyloxy group, n-butoxycarbonyloxy group, tert-butoxycarbonyloxy group, cyclopentyloxycarbonyloxy group and cyclohexyloxycarbonyloxy group.

The ring structure which may be formed by combining two Ri₅ with each other includes a 5- or 6-membered ring, preferably a 5-membered ring (that is, tetrahydrothiophene ring), formed by two R15 together with the sulfur atom in formula (ZI-4) and may be fused with an aryl group or a cycloalkyl group. The divalent R15 may have a substituent, and examples of the substituent include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxyalkyl group, an alkoxycarbonyl group, and an alkoxycarbonyloxy group. As for the substituent on the ring structure, a plurality of substituents may be present, and these substituents may combine with each other to form a ring (for example, an aromatic or non-aromatic hydrocarbon ring, an aromatic or non-aromatic heterocyclic ring, or a polycyclic condensed ring formed by combining two or more of these rings).

In formula (ZI-4), R₁₅ is preferably, for example, a methyl group, an ethyl group, a naphthyl group, or a divalent group capable of forming a tetrahydrothiophene ring structure together with the sulfur atom when two R₁₅ are combined with each other.

The substituent which Rj₃ and RH may have is preferably a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, or a halogen atom (particularly fluorine atom).

1 is preferably 0 or 1 , more preferably 1.

r is preferably from 0 to 2.

Specific examples of the cation in the compound represented by formula (ZI-4) for use in the present invention are illustrated below.

Formulae (ZII) and (ZIII) are described below.

In formulae (ZII) and (ZIII), each of R₂04 to R₂₀7 independently represents an aryl group, an alkyl group or a cycloalkyl group.

The aryl group of R₂₀₄ to R₂₀₇ is preferably a phenyl group or a naphthyl group, more preferably a phenyl group. The aryl group of R₂₀₄ to R207 may be an aryl group having a heterocyclic structure containing an oxygen atom, a nitrogen atom, a sulfur atom or the like. Examples of the framework of the aryl group having a heterocyclic structure include pyrrole, furan, thiophene, indole, benzofuran, and benzothiophene.

The alkyl group and cycloalkyl group in R₂₀₄ to R₂₀₇ are preferably a linear or branched alkyl group having a carbon number of 1 to 10 (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group) and a cycloalkyl group having a carbon number of 3 to 10 (e.g., cyclopentyl group, cyclohexyl group, norbornyl group).

The aryl group, alkyl group and cycloalkyl group of R₂₀4 to R₂₀₇ may have a substituent. Examples of the substituent which may be substituted on the aryl group, alkyl group and cycloalkyl group of R₂₀₄ to R₂₀₇ include an alkyl group (for example, having a carbon number of 1 to 15), a cycloalkyl group (for example, having a carbon number of 3 to 15), an aryl group (for example, having a carbon number of 6 to 15), an alkoxy group (for example, having a carbon number of 1 to 15), a halogen atom, a hydroxyl group, and a phenylthio group.

Z^" represents a non-nucleophilic anion, and examples thereof are the same as those of the non-nucleophilic anion of Z^" in formula (ZI).

Other examples of the acid generator include compounds represented by the following formulae (ZIV), (ZV) and (ZVI):

In formulae (ZIV) to (ZVI), each of Ar₃ and Ar₄ independently represents an aryl group.

Each of R₂₀₈, R₂₀9 and R₂₁₀ independently represents an alkyl group, a cycloalkyl group or an aryl group.

A represents an alkylene group, an alkenylene group or an arylene group.

Specific examples of the aryl group of Ar₃, Ar₄, R₂₀₈, R₂₀9 and R₂]₀ are the same as specific examples of the aryl group of R₂₀₁, R₂₀₂ and R₂₀₃ in formula (ZI-1).

Specific examples of the alkyl group and cycloalkyl group of R₂₀₈, R209 and R₂₁₀ are the same as specific examples of the alkyl group and cycloalkyl group of R₂₀₁, R₂₀₂ and R₂₀₃ in formula (ZI-2).

The alkylene group of A includes an alkylene group having a carbon number of 1 to 12 (e.g., methylene group, ethylene group, propylene group, isopropylene group, butylenes group, isobutylene group); the alkenylene group of A includes an alkenylene group having a carbon number of 2 to 12 (e.g., ethenylene group, propenylene group, butenylene group); and the arylene group of A includes an arylene group having a carbon number of 6 to 10 (e.g., phenylene group, tolylene group, naphthylene group).

Among the acid generators, more preferred are the compounds represented by formulae (ZI) to (ZIII).

Also, the acid generator is preferably a compound that generates an acid having one sulfonic acid group or imide group, more preferably a compound that generates a monovalent perfluoroalkanesulfonic acid, a compound that generates an aromatic sulfonic acid substituted with a monovalent fluorine atom or a fluorine atom-containing group, or a compound that generates an imide acid substituted with a monovalent fluorine atom or a fluorine atom- containing group, still more preferably a sulfonium salt of fluoro-substituted alkanesulfonic acid, fluorine-substituted benzenesulfonic acid, fluorine-substituted imide acid or fluorine- substituted methide acid. In particular, the acid generator which can be used is preferably a compound that generates a fluoro-substituted alkanesulfonic acid, a fluoro-substituted benzenesulfonic acid or a fluoro-substituted imide acid, where pKa of the acid generated is -1 or less, and in this case, the sensitivity is enhanced.

Of acid generators, particularly preferred examples are illustrated below.

(Z108)

The acid generator can be synthesized by a known method, for example, can be synthesized according to the method described in JP-A-2007-161707.

As for the acid generator, one kind may be used alone, or two or more kinds may be used in combination.

The content of the compound capable of generating an acid upon irradiation with an actinic ray or radiation (excluding a case where the compound is represented by formula (ZI- 3) or (ZI-4)) in the composition is preferably from 0.1 to 30 mass%, more preferably from 0.5 to 25 mass%, still more preferably from 3 to 20 mass%, yet still more preferably from 3 to 15 mass%, based on the total solid content of the actinic ray-sensitive or radiation-sensitive resin composition.

In the case where the acid generator is represented by formula (ZI-3) or (ZI-4), the content thereof is preferably from 5 to 35 mass%, more preferably from 8 to 30 mass%, still more preferably from 9 to 30 mass%, yet still more preferably from 9 to 25 mass%, based on the total solid content of the composition. [4] (D) Hydrophobic resin different from the resin (A)

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may contain a hydrophobic resin different from the resin (A) (hereinafter, sometimes referred to as "hydrophobic resin (D)" or simply as "resin (D)") particularly when the composition is applied to immersion exposure. Incidentally, the hydrophobic resin (D) is preferably different from the resin (C).

The hydrophobic resin (D) is unevenly distributed to the film surface layer and when the immersion medium is water, the static/dynamic contact angle of the resist film surface for water as well as the followability of immersion liquid can be enhanced.

The hydrophobic resin (D) is preferably designed to, as described above, be unevenly distributed to the interface but unlike a surfactant, need not have necessarily a hydrophilic group in the molecule and may not contribute to uniform mixing of polar/nonpolar substances.

In view of uneven distribution to the film surface layer, the hydrophobic resin (D) preferably contains at least one of "a fluorine atom", "a silicon atom" and "a CH₃ partial structure contained in the side chain moiety of the resin", more preferably two or more thereof.

In the case where the hydrophobic resin (D) contains a fluorine atom and/or a silicon atom, the fluorine atom and/or silicon atom in the hydrophobic resin (D) may be contained in the main chain of the resin or may be contained in the side chain.

In the case where the hydrophobic resin (D) contains a fluorine atom, the resin preferably contains a fluorine atom-containing alkyl group, a fluorine atom-containing cycloalkyl group or a fluorine atom-containing aryl group, as a fluorine atom-containing partial structure.

The fluorine atom-containing alkyl group (preferably having a carbon number of 1 to 10, more preferably a carbon number of 1 to 4) is a linear or branched alkyl group with at least one hydrogen atom being substituted for by a fluorine atom and may further have a substituent other than fluorine atom.

The fluorine atom-containing cycloalkyl group is a monocyclic or polycyclic cycloalkyl group with at least one hydrogen atom being substituted for by a fluorine atom and may further have a substituent other than fluorine atom.

The fluorine atom-containing aryl group is an aryl group such as phenyl group or naphthyl group with at least one hydrogen atom being substituted for by a fluorine atom and may further have a substituent other than fluorine atom.

As the fluorine atom-containing alkyl group, fluorine atom-containing cycloalkyl group and fluorine atom-containing aryl group, the groups represented by the following formulae (F2) to (F4) are preferred, but the present invention is not limited thereto.

(F2) (F3) (F4)

In formulae (F2) to (F4), each of R₅₇ to R₆₈ independently represents a hydrogen atom, a fluorine atom or an alkyl group (linear or branched), provided that at least one of R57 to R<5i , at least one of R ₂ to R₆₄, and at least one of R₆ to Re₈ each independently represents a fluorine atom or an alkyl group (preferably having a carbon number of 1 to 4) with at least one hydrogen atom being substituted for by a fluorine atom.

It is preferred that all of R₅₇ to R₆₁ and R₆₅ to R₆₇ are a fluorine atom. Each of R₆₂, R₆3 and R₆₈ is preferably an alkyl group (preferably having a carbon number of 1 to 4) with at least one hydrogen atom being substituted for by a fluorine atom, more preferably a perfluoroalkyl group having a carbon number of 1 to 4. R6₂ and R^ may combine with each other to form a ring.

Specific examples of the group represented by formula (F2) include a p- fluorophenyl group, a pentafluorophenyl group, and a 3,5-di(trifluoromethyl)phenyl group.

Specific examples of the group represented by formula (F3) include a trifluoromethyl group, a pentafluoropropyl group, a pentafluoroethyl group, a heptafluorobutyl group, a hexafluoroisopropyl group, a heptafluoroisopropyl group, a hexafluoro(2- methyl)isopropyl group, a nonafluorobutyl group, an octafluoroisobutyl group, a nonafluorohexyl group, a nonafluoro-tert-butyl group, a perfluoroisopentyl group, a perfluorooctyl group, a perfluoro(trimethyl)hexyl group, a 2,2,3,3-tetrafluorocyclobutyl group, and a perfluorocyclohexyl group. Among these, a hexafluoroisopropyl group, a heptafluoroisopropyl group, a hexafluoro(2-methyl)isopropyl group, an octafluoroisobutyl group, a nonafluoro-tert-butyl group and a perfluoroisopentyl group are preferred, and a hexafluoroisopropyl group and a heptafluoroisopropyl group are more preferred.

Specific examples of the group represented by formula (F4) include -C(CF₃)₂OH, - C(C₂F₅)₂OH, -C(CF₃)(CH₃)OH and -CH(CF₃)OH, with -C(CF₃)₂OH being preferred.

The fluorine atom-containing partial structure may be bonded directly to the main chain or may be bonded to the main chain through a group selected from the group consisting of an alkylene group, a phenylene group, an ether bond, a thioether bond, a carbonyl group, an ester bond, an amide bond, a urethane bond and a ureylene bond, or a group formed by combining two or more of these members.

Specific examples of the repeating unit having a fluorine atom are illustrated below, but the present invention is not limited thereto.

In specific examples, Xi represents a hydrogen atom, -CH₃, -F or -CF₃. X₂ represents -F or -CF₃.

The hydrophobic resin (D) may contain a silicon atom. The resin preferably has an alkylsilyl structure (preferably a trialkylsilyl group) or a cyclic siloxane structure, as a silicon atom-containing partial structure.

Specific examples of the alkylsilyl structure and cyclic siloxane structure include the grou s represented by the following formulae (CS-1) to (CS-3):

(CS-1) (CS-2) (CS-3)

In formulae (CS-1) to (CS-3), each of R)₂ to R₂₆ independently represents a linear or branched alkyl group (preferably having a carbon number of 1 to 20) or a cycloalkyl group (preferably having a carbon number of 3 to 20).

Each of L₃ to L₅ represents a single bond or a divalent linking group. The divalent linking group is a single member or a combination of two or more members (preferably having a total carbon number of 12 or less), selected from the group consisting of an alkylene group, a phenylene group, an ether bond, a thioether bond, a carbonyl group, an ester bond, an amide bond, a urethane bond and a urea bond.

n represents an integer of 1 to 5. n is preferably an integer of 2 to 4.

Specific examples of the repeating unit having a group represented by formulae (CS- 1) to (CS-3) are illustrated below, but the present invention is not limited thereto. In specific examples, Xj represents a hydrogen atom, -CH₃, -F or -CF₃.

R=CH3, C2H , C3H7, C4H9

In addition, it is also preferred that, as described above, the hydrophobic resin (D) contains a CH₃ partial structure in the side chain moiety. Here, the CH₃ partial structure contained in the side chain moiety of the resin (D) (hereinafter, sometimes simply referred to as "side chain CH₃ partial structure") encompasses the CH₃ partial structure contained in an ethyl group, a propyl group and the like.

On the other hand, a methyl group bonded directly to the main chain of the resin (D) (for example, an ct-methyl group of a repeating unit having a methacrylic acid structure) little contributes to surface localization of the resin (D) due to the effect of the main chain and therefore, is not encompassed by the CH₃ partial structure of the present invention.

More specifically, in the case where the resin (D) contains, for example, a repeating unit derived from a monomer having a polymerizable moiety with a carbon-carbon double bond, such as repeating unit represented by the following formula (M), and where Rn to Ri₄ are the "very" CH₃, this CH₃ is not encompassed by the C¾ partial structure contained in the side chain moiety of the present invention.

On the other hand, a CH₃ partial structure connected to the C-C main chain through some atom comes under the CH₃ partial structure of the present invention. For example, when Rn is an ethyl group (CH₂CH₃), this is counted as having "one" CH₃ partial structure of the present invention.

In formula (M), each of R to R₁₄ independently represents a side chain moiety.

Examples of the side chain moiety of Rn to Rj₄ include a hydrogen atom and a monovalent organic group.

Examples of the monovalent organic group of R to R14 include an alkyl group, a cycloalkyl group, an aryl group, an alkyloxycarbonyl group, a cycloalkyloxycarbonyl group, an aryloxycarbonyl group, an alkyl aminocarbonyl group, a cycloalkylaminocarbonyl group, and an arylaminocarbonyl group, and these groups may further have a substituent.

The hydrophobic resin (D) is preferably a resin containing a repeating unit having a CH₃ partial structure in the side chain moiety, and it is more preferred to contain, as such a repeating unit, (x) at least one repeating unit out of a repeating unit represented by the following formula (II) and a repeating unit represented by the following formula (III). The repeating unit represented by formula (II) is described in detail below.

In formula (II), represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom, and R₂ represents an organic group having one or more CH₃ partial structures and being stable to acid. Here, the organic group stable to acid is, more specifically, preferably an organic group free from "a group capable of decomposing by the action of an acid to produce a polar group" described for the resin (A).

The alkyl group of X_bi is preferably an alkyl group having a carbon number of 1 to 4, and examples thereof include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a trifiuoromethyl group, with a methyl group being preferred.

X_b! is preferably a hydrogen atom or a methyl group.

R₂ includes an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, and an aralkyl group, each having one or more CH₃ partial structures. These cycloalkyl, alkenyl, cycloalkenyl, aryl and aralkyl groups may further have an alkyl group as a substituent.

R₂ is preferably an alkyl group or an alkyl-substituted cycloalkyl group, each having one or more CH₃ partial structures.

The organic group having one or more C¾ partial structures and being stable to acid of R₂ preferably contains from two to ten, more preferably from two to eight, CH₃ partial structures.

The alkyl group having one or more CH₃ partial structures of R₂ is preferably a branched alkyl group having a carbon number of 3 to 20. Specific preferred examples of the alkyl group include an isopropyl group, an isobutyl group, a 3-pentyl group, a 2-methyl-3- butyl group, a 3-hexyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5- dimethyl-4-pentyl group, an isooctyl group, a 2,4,4-trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a l,5-dimethyl-3-heptyl group, and a 2,3,5,7-tetramethyl-4- heptyl group. Among these, an isobutyl group, a tert-butyl group, a 2-methyl-3 -butyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, a 2,4,4- trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a l,5-dimethyl-3- heptyl group, and a 2,3,5,7-tetramethyl-4-heptyl group are more preferred.

The cycloalkyl group having one or more CH₃ partial structures of R₂ may be monocyclic or polycyclic and specifically includes a group having a carbon number of 5 or more and having a monocyclo, bicyclo, tricyclo or tetracyclo structure or the like. The carbon number thereof is preferably from 6 to 30, more preferably from 7 to 25. The cycloalkyl group is preferably an adamantyl group, a noradamantyl group, a decalin residue, a tricyclodecanyl group, a tetracyclododecanyl group, a norbornyl group, a cedrol group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecanyl group or a cyclododecanyl group, more preferably an adamantyl group, a norbornyl group, a cyclohexyl group, a cyclopentyl group, a tetracyclododecanyl group or a tricyclodecanyl group, still more preferably a norbornyl group, a cyclopentyl group or a cyclohexyl group.

The alkenyl group having one or more CH₃ partial structures of R₂ is preferably a linear or branched alkenyl group having a carbon number of 1 to 20, more preferably a branched alkenyl group.

The aryl group having one or more CH₃ partial structures of R₂ is preferably an aryl group having a carbon number of 6 to 20, and examples thereof include a phenyl group and a naphthyl group, with a phenyl group being preferred.

The aralkyl group having one or more C¾ partial structures of R₂ is preferably an aralkyl group having a carbon number of 7 to 12, and examples thereof include a benzyl group, a phenethyl group and a naphthylmethyl group.

Specific examples of the hydrocarbon group having two or more CH₃ partial structures of R₂ include an isopropyl group, an isobutyl group, a tert-butyl group, a 3-pentyl group, a 2-methyl-3 -butyl group, a 3-hexyl group, a 2,3-dimethyl-2-butyl group, a 2-methyl-3- pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, an isooctyl group, a 2,4,4-trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a 1,5-dimethyl- 3-heptyl group, a 2,3,5,7-tetramethyl-4-heptyl group, a 3,5-dimethylcyclohexyl group, a 4- isopropylcyclohexyl group, a 4-tert-butylcyclohexyl group, and an isobornyl group. Among these, an isobutyl group, a tert-butyl group, a 2-methyl-3 -butyl group, a 2,3-dimethyl-2-butyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, a 2,4,4-trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a 1 ,5-dimethyl- 3-heptyl group, a 2,3,5,7-tetramethyl-4-heptyl group, a 3,5-dimethylcyclohexyl group, a 3,5- di-tert-butylcyclohexyl group, a 4-isopropylcyclohexyl group, a 4-tert-butylcyclohexyl group and an isobornyl group are preferred.

Specific preferred examples of the repeating unit represented by formula (II) are illustrated below but the re ent invention is not limited he e

The repeating unit represented by formula (II) is preferably a repeating unit stable to acid (non-acid-decomposable repeating unit) and specifically, is preferably a repeating unit free from a group capable of decomposing by the action of an acid to produce a polar group. The repeating unit represented by formula (III) is described in detail below.

(III)

In formula (III), Xt,₂ represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom, R₃ represents an organic group having one or more CH₃ partial structures and being stable to acid, and n represents an integer of 1 to 5.

The alkyl group of Xb₂ is preferably an alkyl group having a carbon number of 1 to 4, and examples thereof include a methyl group, an ethyl group, a propyl group, a hydroxymethyl group, and a trifluoromethyl group.

Xb₂ is preferably a hydrogen atom.

R₃ is an organic group stable to acid and therefore, more specifically, is preferably an organic group free from "a group capable of decomposing by the action of an acid to produce a polar group" described for the resin (A).

R₃ includes an alkyl group having one or more CH₃ partial structures.

The organic group having one or more CH₃ partial structures and being stable to acid of R₃ preferably contains from one to ten, more preferably from one to eight, still more preferably from one to four, CH₃ partial structures.

The alkyl group having one or more CH₃ partial structures of R₃ is preferably a branched alkyl group having a carbon number of 3 to 20. Specific preferred examples of the alkyl group include an isopropyl group, an isobutyl group, a 3-pentyl group, a 2-methyl-3- butyl group, a 3-hexyl group, a 2-methyl-3-pentyl group, a 3 -methyl -4-hexyl group, a 3,5- dimethyl-4-pentyl group, an isooctyl group, a 2,4,4-trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a l,5-dimethyl-3-heptyl group, and a 2,3,5,7-tetramethyl-4- heptyl group. Among these, an isobutyl group, a tert-butyl group, a 2-methyl-3 -butyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, a 2,4,4- trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a l,5-dimethyl-3- heptyl group and a 2,3,5,7-tetramethyl-4-heptyl group are more preferred.

Specific examples of the alkyl group having two or more CH₃ partial structures of R₃ include an isopropyl group, an isobutyl group, a tert-butyl group, a 3-pentyl group, a 2,3- dimethylbutyl group, a 2-methyl-3 -butyl group, a 3-hexyl group, a 2-methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, an isooctyl group, a 2,4,4- trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a l,5-dimethyl-3- heptyl group, and a 2,3,5,7-tetramethyl-4-heptyl group. Among these, those having a carbon number of 5 to 20, that is, an isobutyl group, a tert-butyl group, a 2-methyl-3 -butyl group, a 2- methyl-3-pentyl group, a 3-methyl-4-hexyl group, a 3,5-dimethyl-4-pentyl group, a 2,4,4- trimethylpentyl group, a 2-ethylhexyl group, a 2,6-dimethylheptyl group, a l,5-dimethyl-3- heptyl group, a 2,3,5,7-tetramethyl-4-heptyl group and a 2,6-dimethylheptyl group, are preferred.

n represents an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or

2.

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

The repeating unit represented by formula (III) is preferably a repeating unit stable to acid (non-acid-decomposable repeating unit) and specifically, is preferably a repeating unit free from a group capable of decomposing by the action of an acid to produce a polar group.

In the case where the resin (D) contains a CH₃ partial structure in the side chain moiety and furthermore, does not have a fluorine atom and a silicon atom, the content of the (x) at least one repeating unit out of a repeating unit represented by formula (II) and a repeating unit represented by formula (III) is preferably 90 mol% or more, more preferably 95 mol% or more, based on all repeating units in the resin (C). The content is usually 100 mol% or less based on all repeating units in the resin (C).

When the resin (D) contains the (x) at least one repeating unit out of a repeating unit represented by formula (II) and a repeating unit represented by formula (III) in a ratio of 90 mol% or more based on all repeating units in the resin (D), the surface free energy of the resin (C) is increased and in turn, the resin (D) is less likely to be unevenly distributed to the surface of the resist film, as a result, the static/dynamic contact angle of the resist film for water can be unfailingly raised and the followability of immersion liquid can be enhanced.

Furthermore, in both cases of (i) containing a fluorine atom and/or a silicon atom and (ii) containing a CH₃ partial structure in the side chain moiety, the hydrophobic resin (D) may contain at least one group selected from the group consisting of the following (x) to (z):

(x) an acid group,

(y) a lactone structure-containing group, an acid anhydride group, or an acid imide group, and

(z) a group capable of decomposing by the action of an acid.

Examples of the acid group (x) include a phenolic hydroxyl group, a carboxylic acid group, a fluorinated alcohol group, a sulfonic acid group, a sulfonamide group, a sulfonylimide group, an (alkylsulfonyl)(alkylcarbonyl)methylene group, an (alkylsulfonyl)(alkylcarbonyl)imide group, a bis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imide group, a bis(alkylsulfonyl)methylene group, a bis(alkylsulfonyl)imide group, a tris(alkylcarbonyl)methylene group, and a tris(alkylsulfonyl)methylene group.

Preferred acid groups include a fluorinated alcohol group (preferably hexafluoroisopropanol), a sulfonimide group ,and a bis(alkylcarbonyl)methylene group.

The repeating unit having (x) an acid group includes, for example, a repeating unit where the acid group is directly bonded to the main chain of the resin, such as repeating unit by an acrylic acid or a methacrylic acid, and a repeating unit where the acid group is bonded to the main chain of the resin through a linking group, and the acid group may be also introduced into the polymer chain terminal by using an acid group-containing polymerization initiator or chain transfer agent at the polymerization. All of these cases are preferred. The repeating unit having (x) an acid group may have at least either a fluorine atom or a silicon atom.

The content of the repeating unit having (x) an acid group is preferably from 1 to 50 mol%, more preferably from 3 to 35 mol%, still more preferably from 5 to 20 mol%, based on all repeating units in the hydrophobic resin (D).

Specific examples of the repeating unit having (x) an acid group are illustrated below, but the present invention is not limited thereto. In the formulae, Rx represents a hydrogen atom, CH₃, CF₃ or CH₂OH.

The (y) lactone structure-containing group, acid anhydride group or acid imide group is preferably a lactone structure-containing group.

The repeating unit containing such a group is, for example, a repeating unit where the group is directly bonded to the main chain of the resin, such as repeating unit by an acrylic acid ester or a methacrylic acid ester. This repeating unit may be a repeating unit where the group is bonded to the main chain of the resin through a linking group. Alternatively, in this repeating unit, the group may be introduced into the terminal of the resin by using a polymerization initiator or chain transfer agent containing the group at the polymerization.

Examples of the repeating unit having a lactone structure-containing group are the same as those of the repeating unit having a lactone structure described above in the paragraph of the acid-decomposable resin (A).

The content of the repeating unit having a lactone structure-containing group, an acid anhydride group or an acid imide group is preferably from 1 to 100 mol%, more preferably from 3 to 98 mol%, still more preferably from 5 to 95 mol%, based on all repeating units in the hydrophobic resin (D).

Examples of the repeating unit having (z) a group capable of decomposing by the action of an acid, contained in the hydrophobic resin (D), are the same as those of the repeating unit having an acid-decomposable group described for the resin (A). The repeating unit having (z) a group capable of decomposing by the action of an acid may contain at least either a fluorine atom or a silicon atom. In the hydrophobic resin (D), the content of the repeating unit having (z) a group capable of decomposing by the action of an acid is preferably from 1 to 80 mol%, more preferably from 10 to 80 mol%, still more preferably from 20 to 60 mol%, based on all repeating units in the resin (D). The hydrophobic resin (D) may further contain a repeating unit represented by the following formula (III):

Π^Ι)

In formula (III), R_c3i represents a hydrogen atom, an alkyl group (which may be substituted with a fluorine atom or the like), a cyano group or a -CH₂-0-R_ac2 group, wherein R_ac2 represents a hydrogen atom, an alkyl group or an acyl group. R_c3i is preferably a hydrogen atom, a methyl group, a hydroxymethyl group or a trifluoromethyl group, more preferably a hydrogen atom or a methyl group.

Rc32 represents a group having an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group or an aryl group. These groups may be substituted with a fluorine atom or a silicon atom-containing group.

L_c3 represents a single bond or a divalent linking group.

In formula (III), the alkyl group of R_c32 is preferably a linear or branched alkyl group having a carbon number of 3 to 20.

The cycloalkyl group is preferably a cycloalkyl group having a carbon number of 3 to 20.

The alkenyl group is preferably an alkenyl group having a carbon number of 3 to 20. The cycloalkenyl group is preferably a cycloalkenyl group having a carbon number of 3 to 20.

The aryl group is preferably an aryl group having a carbon number of 6 to 20, more preferably a phenyl group or a naphthyl group, and these groups may have a substituent.

R_C32 is preferably an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom.

The divalent linking group of L_c3 is preferably an alkylene group (preferably having a carbon number of 1 to 5), an ether bond, a phenylene group or an ester bond (a group represented by -COO-).

The content of the repeating unit represented by formula (III) is preferably from 1 to 100 mol%, more preferably from 10 to 90 mol%, still more preferably from 30 to 70 mol%, based on all repeating units in the hydrophobic resin.

It is also preferred that the hydrophobic resin (D) further contains a repeating unit represented by the following formula (CII-AB):

( C I I - A B )

In formula (CII-AB), each of R_cn' and R_ci₂' independently represents a hydrogen atom, a cyano group, a halogen atom or an alkyl group.

Zc represents an atomic group for forming an alicyclic structure containing two carbon atoms (C-C) to which Z_c' is bonded.

The content of the repeating unit represented by formula (CII-AB) is preferably from 1 to 100 mol%, more preferably from 10 to 90 mol%, still more preferably from 30 to 70 mol%, based on all repeating units in the hydrophobic resin.

Specific examples of the repeating units represented by formulae (III) and (CII-AB) are illustrated below, but the present invention is not limited thereto. In the formulae, Ra represents H, CH₃, CH₂OH, CF₃ or CN.

o

In the case where the hydrophobic resin (D) contains a fluorine atom, the fluorine atom content is preferably from 5 to 80 mass%, more preferably from 10 to 80 mass%, based on the weight average molecular weight of the hydrophobic resin (D). Also, the fluorine atom-containing repeating unit preferably accounts for 10 to 100 mol%, more preferably from 30 to 100 mol%, based on all repeating units contained in the hydrophobic resin (D).

In the case where the hydrophobic resin (D) contains a silicon atom, the silicon atom content is preferably from 2 to 50 mass%, more preferably from 2 to 30 mass%, based on the weight average molecular weight of the hydrophobic resin (D). Also, the silicon atom- containing repeating unit preferably accounts for 10 to 100 mol%, more preferably from 20 to 100 mol%, based on all repeating units contained in the hydrophobic resin (D).

On the other hand, particularly when the resin (D) contains a C¾ partial structure in the side chain moiety, an embodiment where the resin (D) substantially free from a fluorine atom and a silicon atom is also preferred, and in this case, specifically, the content of the repeating unit having a fluorine atom or a silicon atom is, based on all repeating units in the resin (D), preferably 5 mol% or less, more preferably 3 mol% or less, still more preferably 1 mol% or less, and ideally 0%, that is, not containing a fluorine atom and a silicon atom. Also, the resin (D) preferably consists substantially of only a repeating unit composed of only an atom selected from a carbon atom, an oxygen atom, a hydrogen atom, a nitrogen atom and a sulfur atom. More specifically, the repeating unit composed of only an atom selected from a carbon atom, an oxygen atom, a hydrogen atom, a nitrogen atom and a sulfur atom accounts for preferably 95 mol% or more, more preferably 97 mol% or more, still more preferably 99 mol% or more, and ideally 100 mol%, based on all repeating units in the resin (D).

The weight average molecular weight of the hydrophobic resin (D) is, in terms of standard polystyrene, preferably from 1,000 to 100,000, more preferably from 1,000 to 50,000, still more preferably from 2,000 to 15,000.

As for the hydrophobic resin (D), one resin may be used, or a plurality of resins may be used in combination.

The content of the hydrophobic resin (D) in the composition is preferably from 0.01 to 10 mass%, more preferably from 0.05 to 8 mass%, still more preferably from 0.1 to 5 mass%, based on the total solid content of the composition of the present invention.

In the hydrophobic resin (D), similarly to the resin (A), it is of course preferred that the content of impurities such as metal is small, but the content of residual monomers or oligomer components is also preferably from 0.01 to 5 mass%, more preferably from 0.01 to 3 mass%, still more preferably from 0.05 to 1 mass%. Within this range, an actinic ray- sensitive or radiation-sensitive resin composition free from in-liquid extraneous substances and change with aging of sensitivity or the like can be obtained. Furthermore, in view of resolution, resist profile, side wall of resist pattern, roughness and the like, the molecular weight distribution (Mw/Mn, sometimes referred to as "polydispersity") is preferably from 1 to 5, more preferably from 1 to 3, still more preferably from 1 to 2.

As the hydrophobic resin (D), various commercially products may be used, or the resin may be synthesized by a conventional method (for example, radical polymerization). Examples of the general synthesis method include a batch polymerization method of dissolving monomer species and an initiator in a solvent and heating the solution, thereby effecting the polymerization, and a dropping polymerization method of adding dropwise a solution containing monomer species and an initiator to a heated solvent over 1 to 10 hours. A dropping polymerization method is preferred.

The reaction solvent, the polymerization initiator, the reaction conditions (such as temperature and concentration) and the method for purification after reaction are the same as those described for the resin (A), but in the synthesis of the hydrophobic resin (D), the concentration at the reaction is preferably from 30 to 50 mass%.

Specific examples of the hydrophobic resin (D) are illustrated below. Also, the molar ratio of repeating units (corresponding to repeating units starting from the left), weight average molecular weight and olydispersity of each resin are shown in the Tables later.

(HR-49) (HR-50) (HR-51) (HR-52)

(HR-64) (HR-6S)

Resin Composition Mw Mw/Mn Resin Composition Mw Mw/Mn

HR-1 50/50 4900 1.4 HR-36 50/50 6000 1.5

HR-2 50/50 5100 1.6 HR-37 50/50 5000 1.6

HR-3 50/50 4800 1.5 HR-38 50/50 4000 1.4

HR-4 50/50 5300 1.6 HR-39 20/80 6000 1.4

HR-5 50/50 4500 1.4 HR-40 50/50 7000 1.4

HR-6 100 5500 1.6 HR-41 50/50 6500 1.6

HR-7 50/50 5800 1.9 HR-42 50/50 5200 1.6

HR-8 50/50 4200 1.3 HR-43 50/50 6000 1.4

HR-9 50/50 5500 1.8 HR-44 70/30 5500 1.6

HR-10 40/60 7500 1.6 HR-45 50/20/30 4200 1.4

HR-1 1 70/30 6600 1.8 HR-46 30/70 7500 1.6

HR-12 40/60 3900 1.3 HR-47 40/58/2 4300 1.4

HR-13 50/50 9500 1.8 HR-48 50/50 6800 1.6

HR-14 50/50 5300 1.6 HR-49 100 6500 1.5

HR-15 100 6200 1.2 HR-50 50/50 6600 1.6

HR-16 100 5600 1.6 HR-51 30/20/50 6800 1.7

HR-17 100 4400 1.3 HR-52 95/5 5900 1.6

HR-18 50/50 4300 1.3 HR-53 40/30/30 4500 1.3

HR-19 50/50 6500 1.6 HR-54 50/30/20 6500 1.8

HR-20 30/70 6500 1.5 HR-55 30/40/30 7000 1.5

HR-21 50/50 6000 1.6 HR-56 60/40 5500 1.7

HR-22 50/50 3000 1.2 HR-57 40/40/20 4000 1.3

HR-23 50/50 5000 1.5 HR-58 60/40 3800 1.4

HR-24 50/50 4500 1.4 HR-59 80/20 7400 1.6

HR-25 30/70 5000 1.4 HR-60 40/40/15/5 4800 1.5

HR-26 50/50 5500 1.6 HR-61 60/40 5600 1.5

HR-27 50/50 3500 1.3 HR-62 50/50 5900 2.1

HR-28 50/50 6200 1.4 HR-63 80/20 7000 1.7

HR-29 50/50 6500 1.6 HR-64 100 5500 1.8

HR-30 50/50 6500 1.6 HR-65 50/50 9500 1.9

HR-31 50/50 4500 1.4

HR-32 30/70 5000 1.6

HR-33 30/30/40 6500 1.8

HR-34 50/50 4000 1.3

HR-35 50/50 6500 1.7

(C-22) (C-23) (C-24)

(D-2)

(D-3) (D-4)

(D-5) (D-6)

(D-7) (D-8)

(D-9)

(D-10)

(D-ll) (D-12)

(D-15)

Resin Composition Mw Mw/Mn

C-l 50/50 9600 1.74

C-2 60/40 34500 1.43

C-3 30/70 19300 1.69

C-4 90/10 26400 1.41

C-5 100 27600 1.87

C-6 80/20 4400 1.96

C-l 100 16300 1.83

C-8 5/95 24500 1.79

C-9 20/80 15400 1.68

C-10 50/50 23800 1.46

C-l l 100 22400 1.57

C-12 10/90 21600 1.52

C-13 100 28400 1.58

C-14 50/50 16700 1.82

C-15 100 23400 1.73

C-16 60/40 18600 1.44

C-17 80/20 12300 1.78

C-18 40/60 18400 1.58

C-19 70/30 12400 1.49

C-20 50/50 23500 1.94

C-21 10/90 7600 1.75

C-22 5/95 14100 1.39

C-23 50/50 17900 1.61

C-24 10/90 24600 1.72

C-25 50/40/10 23500 1.65

C-26 60/30/10 13100 1.51

C-27 50/50 21200 1.84

C-28 10/90 19500 1.66 Resin Composition Mw Mw/Mn

D-l 50/50 16500 1.72

D-2 10/50/40 18000 1.77

D-3 5/50/45 27100 1.69

D-4 20/80 26500 1.79

D-5 10/90 24700 1.83

D-6 10/90 15700 1.99

D-7 5/90/5 21500 1.92

D-8 5/60/35 17700 2.10

D-9 35/35/30 25100 2.02

D-10 70/30 19700 1.85

D-l l 75/25 23700 1.80

D-12 10/90 20100 2.02

D-13 5/35/60 30100 2.17

D-14 5/45/50 22900 2.02

D-15 15/75/10 28600 1.81

D-16 25/55/20 27400 1.87

[5-1] (N) Basic compound or ammonium salt compound, whose basicity decreases upon irradiation with an actinic ray or radiation

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention preferably contains a basic compound or an ammonium salt compound, whose basicity decreases upon irradiation with an actinic ray or radiation (hereinafter sometimes referred to as "compound (N)").

The compound (N) is preferably (N-l) a compound having a basic functional group or an ammonium group and a group capable of generating an acidic functional group upon irradiation with an actinic ray or radiation. That is, the compound (N) is preferably a basic compound having a basic functional group and a group capable of generating an acidic functional group upon irradiation with an actinic ray or radiation, or an ammonium salt compound having an ammonium group and a group capable of generating an acidic functional group upon irradiation with an actinic ray or radiation.

The compound which is generated by the decomposition of the compound (N) or (N- 1) upon irradiation with an actinic ray or radiation and whose basicity is decreased includes compounds represented by the following formulae (PA-I), (PA-II) and (PA-III), and from the standpoint that excellent effects can be attained in a high level in terms of all of LWR, local pattern dimension uniformity and DOF, compounds represented by formulae (PA-II) and (PA- III) are preferred.

The compound represented by formula (PA-I) is described below.

Q-A,-(X)„-B-R (PA-I)

In formula (PA-I), Aj represents a single bond or a divalent linking group. Q represents -S0₃H or -C0 H. Q corresponds to an acidic functional group that is generated upon irradiation with an actinic ray or radiation.

X represents -S0₂- or -CO-,

n represents 0 or 1.

B represents a single bond, an oxygen atom or -N(Rx)-.

Rx represents a hydrogen atom or a monovalent organic group.

R represents a monovalent organic group having a basic functional group, or a monovalent organic group having an ammonium group.

The divalent linking group of Ai is preferably a divalent organic group having a carbon number of 2 to 12, and examples thereof include an alkylene group and a phenylene group. An alkylene group having at least one fluorine atom is preferred, and the carbon number thereof is preferably from 2 to 6, more preferably from 2 to 4. The alkylene chain may contain a linking group such as oxygen atom and sulfur atom. The alkylene group is preferably an alkylene group where from 30 to 100% by number of hydrogen atoms are replaced by a fluorine atom, more preferably an alkylene group where the carbon atom bonded to the Q site has a fluorine atom, still more preferably a perfluoroalkylene group, yet still more preferably a perfluoroethylene group, a perfluoropropylene group or a perfluorobutylene group.

The monovalent organic group of Rx is preferably a monovalent organic group having a carbon number of 4 to 30, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group.

The alkyl group of Rx may have a substituent and is preferably a linear or branched alkyl group having a carbon number of 1 to 20, and the alkyl chain may contain an oxygen atom, a sulfur atom or a nitrogen atom.

Here, the alkyl group having a substituent includes particularly a group where a cycloalkyl group is substituted on a linear or branched alkyl group (for example, an adamantylmethyl group, an adamantylethyl group, a cycohexylethyl group and a camphor residue).

The cycloalkyl group of Rx may have a substituent and is preferably a cycloalkyl group having a carbon number of 3 to 20, and the ring may contain an oxygen atom.

The aryl group of Rx may have a substituent and is preferably an aryl group having a carbon number of 6 to 14.

The aralkyl group of Rx may have a substituent and is preferably an aralkyl group having a carbon number of 7 to 20.

The alkenyl group of Rx may have a substituent, and examples thereof include a group having a double bond at an arbitrary position of the alkyl group recited as Rx.

Preferred examples of the partial structure of the basic functional group include a crown ether structure, a primary to tertiary amine structure, and a nitrogen-containing heterocyclic structure (e.g., pyridine, imidazole, pyrazine).

Preferred examples of the partial structure of the ammonium group include a primary to tertiary ammonium structure, a pyridinium structure, an imidazolinium structure, and a pyrazinium structure.

The basic functional group is preferably a functional group having a nitrogen atom, more preferably a structure having a primary to tertiary amino group or a nitrogen-containing heterocyclic structure. In such a structure, from the standpoint of enhancing the basicity, all atoms adjacent to nitrogen atom contained in the structure are preferably a carbon atom or a hydrogen atom. Also, in view of enhancing the basicity, an electron-withdrawing functional group (e.g., carbonyl group, sulfonyl group, cyano group, halogen atom) is preferably not bonded directly to nitrogen atom.

The monovalent organic group in the monovalent organic group (group R) containing such a structure is preferably an organic group having a carbon number of 4 to 30, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group. Each of these groups may have a substituent.

Examples of the alkyl group, cycloalkyl group, aryl group, aralkyl group and alkenyl group in the alkyl group, cycloalkyl group, aryl group, aralkyl group and alkenyl group each containing a basic functional group or an ammonium group of R are the same as those of the alkyl group, cycloalkyl group, aryl group, aralkyl group and alkenyl group recited as Rx.

Examples of the substituent which each of the groups above may have include a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxy group, a carbonyl group, a cycloalkyl group (preferably having a carbon number of 3 to 10), an aryl group (preferably having a carbon number of 6 to 14), an alkoxy group (preferably having a carbon number of 1 to 10), an acyl group (preferably having a carbon number of 2 to 20), an acyloxy group (preferably having a carbon number of 2 to 10), an alkoxycarbonyl group (preferably having a carbon number of 2 to 20), and an aminoacyl group (preferably having a carbon number of 2 to 20). The cyclic structure in the aryl group, cycloalkyl group and the like may further have an alkyl group (preferably having a carbon number of 1 to 20) as a substituent. The aminoacyl group may further have one or two alkyl groups (preferably having a carbon number of 1 to 20) as a substituent.

When B is -N(Rx)-, R and Rx are preferably combined to form a ring. By forming a ring structure, the stability is enhanced, and storage stability of the composition using this compound is also enhanced. The number of carbons constituting the ring is preferably from 4 to 20, and the ring may be monocyclic or polycyclic and may contain an oxygen atom, a sulfur atom or a nitrogen atom.

Examples of the monocyclic structure include a 4- to 8-membered ring containing a nitrogen atom. Examples of the polycyclic structure include a structure formed by combining two monocyclic structures or three or more monocyclic structures. The monocyclic structure and polycyclic structure may have a substituent, and preferred examples of the substituent include a halogen atom, a hydroxyl group, a cyano group, a carboxy group, a carbonyl group, a cycloalkyl group (preferably having a carbon number of 3 to 10), an aryl group (preferably having a carbon number of 6 to 14), an alkoxy group (preferably having a carbon number of 1 to 10), an acyl group (preferably having a carbon number of 2 to 15), an acyloxy group (preferably having a carbon number of 2 to 15), an alkoxycarbonyl group (preferably having a carbon number of 2 to 15), and an aminoacyl group (preferably having a carbon number of 2 to 20). The cyclic structure in the aryl group, cycloalkyl group and the like may further have an alkyl group (preferably having a carbon number of 1 to 15) as a substituent. The aminoacyl group may have one or two alkyl groups (preferably having a carbon number of 1 to 15) as a substituent.

Out of the compounds represented by formula (PA-I), a compound where the Q site is a sulfonic acid can be synthesized using a general sulfonamidation reaction. For example, this compound can be obtained by a method of selectively reacting one sulfonyl halide moiety of a bis-sulfonyl halide compound with an amine compound to form a sulfonamide bond and then hydrolyzing the other sulfonyl halide moiety, or a method of ring-opening a cyclic sulfonic anhydride through a reaction with an amine compound. The compound represented by formula (PA-II) is described below. Q_!-Xi-NH-X₂-Q₂ (PA-II)

In formula (PA-II), each of Qj and Q₂ independently represents a monovalent organic group, provided that either one of Qi and Q₂ has a basic functional group. It is also possible that Qj and Q₂ are combined to form a ring and the ring formed has a basic functional group.

Each of Xi and X₂ independently represents -CO- or -S0₂-.

Here, -NH- corresponds to an acidic functional group that is generated upon irradiation with an actinic ray or radiation.

The monovalent organic group of Q_\ and Q₂ in formula (PA-II) is preferably a monovalent organic group having a carbon number of 1 to 40, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group.

The alkyl group of Qi and Q₂ may have a substituent and is preferably a linear or branched alkyl group having a carbon number of 1 to 30, and the alkyl chain may contain an oxygen atom, a sulfur atom or a nitrogen atom.

The cycloalkyl group of Qj and Q₂ may have a substituent and is preferably a cycloalkyl group having a carbon number of 3 to 20, and the ring may contain an oxygen atom or a nitrogen atom.

The aryl group of Qj and Q₂ may have a substituent and is preferably an aryl group having a carbon number of 6 to 14.

The aralkyl group of Qj and Q₂ may have a substituent and is preferably an aralkyl group having a carbon number of 7 to 20.

The alkenyl group of Qi and Q₂ may have a substituent and includes a group having a double bond at an arbitrary position of the alkyl group above.

Examples of the substituent which each of the groups above may have include a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxy group, a carbonyl group, a cycloalkyl group (preferably having a carbon number of 3 to 10), an aryl group (preferably having a carbon number of 6 to 14), an alkoxy group (preferably having a carbon number of 1 to 10), an acyl group (preferably having a carbon number of 2 to 20), an acyloxy group (preferably having a carbon number of 2 to 10), an alkoxycarbonyl group (preferably having a carbon number of 2 to 20), and an aminoacyl group (preferably having a carbon number of 2 to 10). The cyclic structure in the aryl group, cycloalkyl group and the like may further have an alkyl group (preferably having a carbon number of 1 to 10) as a substituent. The aminoacyl group may further have an alkyl group (preferably having a carbon number of 1 to 10) as a substituent. Examples of the alkyl group having a substituent include a perfluoroalkyl group such as perfluoromethyl group, perfluoroethyl group, perfluoropropyl group and perfluorobutyl group.

Preferred examples of the partial structure of the basic functional group contained in at least either Q_\ or Q₂ are the same as those described for the basic functional group contained in R of formula (PA-I).

Examples of the structure where Qi and Q₂ are combined to form a ring and the ring formed has a basic functional group include a structure where an alkylene group, an oxy group, an imino group or the like is further bonded to the organic group of Qi or Q₂.

In formula (PA-II), at least either one of X_\ and X₂ is preferably -S0₂-.

The compound represented by formula (PA-III) is described below.

Q₁-X₁-NH-X₂-A₂-(X₃)_m-B-Q₃ (PA-III)

In formula (PA-III), each of Qj and Q₃ independently represents a monovalent organic group, provided that either one of Qi and Q₃ has a basic functional group. It is also possible that Qi and Q₃ are combined to form a ring and the ring formed has a basic functional group.

Each of Xi, X₂ and X₃ independently represents -CO- or -S0₂-.

A₂ represents a divalent linking group.

B represents a single bond, an oxygen atom or -N(Qx)-.

Qx represents a hydrogen atom or a monovalent organic group.

When B is -N(Qx)-, Q₃ and Qx may combine to form a ring.

m represents 0 or 1.

Qi has the same meaning as Qi in formula (PA-II).

Examples of the organic group of Q₃ are the same as those of the organic group of Q i and Q₂ in formula (PA-II).

Examples of the structure where Qj and Q₃ are combined to form a ring and the ring formed has a basic functional group include a structure where an alkylene group, an oxy group, an imino group or the like is further bonded to the organic group of or Q₃.

The divalent linking group of A₂ is preferably a fluorine atom-containing divalent linking group having a carbon number of 1 to 8, and examples thereof include a fluorine atom- containing alkylene group having a carbon number of 1 to 8, and a fluorine atom-containing phenylene group. A fluorine atom-containing alkylene group is more preferred, and the carbon number thereof is preferably from 2 to 6, more preferably from 2 to 4. The alkylene chain may contain a linking group such as oxygen atom and sulfur atom. The alkylene group is preferably an alkylene group where from 30 to 100% by number of hydrogen atoms are replaced by a fluorine atom, more preferably a perfluoroalkylene group, still more preferably a perfluoroalkylene group having a carbon number of 2 to 4.

The monovalent organic group of Qx is preferably an organic group having a carbon number of 4 to 30, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group. Examples of the alkyl group, cycloalkyl group, aryl group, aralkyl group and alkenyl group are the same as those for Rx in formula

(PA-I).

In formula (PA-III), each of Xj, X₂ and X₃ is preferably -S0₂-.

The compound (N) is preferably a sulfonium salt compound of the compound represented by formula (PA-I), (PA-II) or (PA-III), or an iodonium salt compound of the compound represented by formula (PA-I), (PA-II) or (PA-III), more preferably a compound represented by the following formula (PA1) or (PA2):

(PA1 ) (PA2)

In formula (PA1), each of R'₂₀₁, R'₂₀₂ and R'₂₀₃ independently represents an organic group, and specific examples thereof are the same as those for R₂₀i, R₂₀₂ and R₂₀₃ in formula (ZI) of the component (B).

X^" represents a sulfonate or carboxylate anion resulting from removal of a hydrogen atom in the -S0₃H moiety or -COOH moiety of the compound represented by formula (PA-I), or an anion resulting from removal of a hydrogen atom in the -NH- moiety of the compound represented by formula (PA-II) or (PA-III).

In formula (PA2), each of R'₂₀₄ and R'₂₀₅ independently represents an aryl group, an alkyl group or a cycloalkyl group. Specific examples thereof are the same as those for R₂₀₄ and R₂₀₅ in formula (ZII) of the component (B).

X^" represents a sulfonate or carboxylate anion resulting from removal of a hydrogen atom in the -SO3H moiety or -COOH moiety of the compound represented by formula (PA-I), or an anion resulting from removal of a hydrogen atom in the -NH- moiety of the compound represented by formula (PA-II) or (PA-III).

The compound (N) decomposes upon irradiation with an actinic ray or radiation to generate, for example, a compound represented by formula (PA-I), (PA-II) or (PA-III).

The compound represented by formula (PA-I) is a compound having a sulfonic acid group or a carboxylic acid group together with a basic functional group or an ammonium group and thereby being reduced in or deprived of the basicity or changed from basic to acidic, relative to the compound (N).

The compound represented by formula (PA-II) or (PA-III) is a compound having an organic sulfonylimino group or an organic carbonylimino group together with a basic functional group and thereby being reduced in or deprived of the basicity or changed from basic to acidic, relative to the compound (N).

In the present invention, the "reduced in the basicity upon irradiation with an actinic ray or radiation" means that the acceptor property for a proton (an acid generated upon irradiation with an actinic ray or radiation) of the compound (N) is decreased by the irradiation with an actinic ray or radiation. The "reduced in the acceptor property" means that when an equilibrium reaction of producing a noncovalent bond complex as a proton adduct from a basic functional group-containing compound and a proton takes place or when an equilibrium reaction of exchanging the counter cation of the ammonium group-containing compound with a proton takes place, the equilibrium constant in the chemical equilibrium decreases.

A compound (N) whose basicity decreases upon irradiation with an actinic ray or radiation is contained in the resist film, so that in the unexposed area, the acceptor property of the compound (N) is sufficiently brought out and an unintended reaction between an acid diffused from the exposed area or the like and the resin (A) can be inhibited, whereas in the exposed area, the acceptor property of the compound (N) decreases and the intended reaction of an acid with the resin (A) unfailingly occurs. It is presumed that by virtue of such an operation mechanism, a pattern excellent in terms of line width roughness (LWR), local pattern dimension uniformity, focus latitude (DOF) and pattern profile is obtained.

The basicity can be confirmed by measuring the pH, or a calculated value can be computed using a commercially available software.

Specific examples of the compound (N) capable of generating a compound represented by formula (PA-I) upon irradiation with an actinic ray or radiation are illustrated below, but the present invention is not limited thereto.

S⁺ 0₃S(CF₂)3S02-0 ^■P V-s'⁺ ~0₃S(CF₂)₃S0₂-N - -5) (PA-6)

OH

Or S⁺ 0₃SCH₂CH₂-N S⁺ 0₃SCH₂CH(OH)CH₂-N 0

OH

> (PA-19) (PA-20)

These compounds can be easily synthesized from a compound represented by formula (PA-I) or a lithium, sodium or potassium salt thereof and a hydroxide, bromide, chloride or the like of iodonium or sulfonium, by utilizing the salt exchange method described in JP-T-1 1-501909 (the term "JP-T" as used herein means a "published Japanese translation of a PCT patent application") or JP-A-2003-246786. The synthesis may be also performed in accordance with the synthesis method described in JP-A-7-333851.

Specific examples of the compound (N) capable of generating a compound represented by formula (PA-II) or (PA-III) upon irradiation with an actinic ray or radiation are illustrated below, but the present invention is not limited thereto. 

These compounds can be easily synthesized using a general sulfonic acid esterification reaction or sulfonamidation reaction. For example, the compound may be obtained by a method of selectively reacting one sulfonyl halide moiety of a bis-sulfonyl halide compound with an amine, alcohol or the like containing a partial structure represented by formula (PA-II) or (PA-III) to form a sulfonamide bond or a sulfonic acid ester bond and then hydrolyzing the other sulfonyl halide moiety, or a method of ring-opening a cyclic sulfonic anhydride by an amine or alcohol containing a partial structure represented by formula (PA-II). The amine or alcohol containing a partial structure represented by formula (PA-II) or (PA-III) can be synthesized by reacting an amine or alcohol with an anhydride (e.g., (R'0₂C)₂0, (R'S0₂)₂0) or an acid chloride compound (e.g., R'0₂CC1, R'S0₂C1) under basic conditions (R' is, for example, a methyl group, an n-octyl group or a trifluoromethyl group). In particular, the synthesis may be performed in accordance with synthesis examples and the like in JP-A-2006-330098.

The molecular weight of the compound (N) is preferably from 500 to 1,000.

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may or may not contain the compound (N), but in the case of containing the compound (N), the content thereof is preferably from 0.1 to 20 mass%, more preferably from 0.1 to 10 mass%, based on the solid content of the actinic ray-sensitive or radiation-sensitive resin composition.

[5-2] (Ν') Basic compound

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may contain (Ν') a basic compound different from the resin (A) so as to reduce the change in performance with aging from exposure to heating.

Preferred basic compounds as the basic compound (Ν') include compounds having a structure represented by the following formulae (Α') to (Ε'):

RA²⁰¹ ! ! A²⁰⁴ I RA²⁰⁵ RA²⁰⁰— N— RA²⁰² — N— C =N - =C— N =C— . — C— N— RA²⁰³ -C N C-RA²⁰⁶

(Α') (Β') (C) (D-) (Ε')

In formulae (Α') and (Ε'), each of RA²⁰⁰, RA²⁰¹ and RA²⁰², which may be the same or different, represents a hydrogen atom, an alkyl group (preferably having a carbon number of 1 to 20), a cycloalkyl group (preferably having a carbon number of 3 to 20) or an aryl group 201 202

(having a carbon number of 6 to 20), and RA and RA may combine with each other to form a ring. Each of RA²⁰³, RA²⁰⁴, RA²⁰⁵ and RA²⁰⁶, which may be the same or different, represents an alkyl group (preferably having a carbon number of 1 to 20).

The alkyl group may have a substituent, and the alkyl group having a substituent is preferably an aminoalkyl group having a carbon number of 1 to 20, a hydroxyalkyl group having a carbon number of 1 to 20, or a cyanoalkyl group having a carbon number of 1 to 20.

The alkyl group in formulae (Α') and (Ε') is more preferably unsubstituted.

Specific preferred examples of the basic compound (Ν') include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, and piperidine. More preferred specific examples of the compound include a compound having an imidazole structure, a diazabicyclo structure, an onium hydroxide structure, an onium carboxylate structure, a trialkylamine structure, an aniline structure or a pyridine structure; an alkylamine derivative having a hydroxyl group and/or an ether bond; and an aniline derivative having a hydroxyl group and/or an ether bond.

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

Other preferred basic compounds include a phenoxy group-containing amine compound, a phenoxy group-containing ammonium salt compound, a sulfonic acid ester group-containing amine compound, and a sulfonic acid ester group-containing ammonium salt compound.

In the phenoxy group-containing amine compound, phenoxy group-containing ammonium salt compound, sulfonic acid ester group-containing amine compound and sulfonic acid ester group-containing ammonium salt compound, at least one alkyl group is preferably bonded to the nitrogen atom and also, the alkyl chain preferably contains an oxygen atom therein to form an oxyalkylene group. The number of oxyalkylene groups in the molecule is 1 or more, preferably from 3 to 9, more preferably from 4 to 6. Among oxyalkylene groups, those having a structure of -CH₂CH₂0-, -CH(CH₃)CH₂0- or -CH₂CH₂CH₂0- are preferred.

Specific examples of the phenoxy group-containing amine compound, phenoxy group-containing ammonium salt compound, sulfonic acid ester group-containing amine compound and sulfonic acid ester group-containing ammonium salt compound include, but are not limited to, Compounds (Cl-1) to (C3-3) illustrated in paragraph [0066] of U.S. Patent Application Publication No. 2007/0224539.

A nitrogen-containing organic compound having a group capable of leaving by the action of an acid may be also used as a kind of the basic compound. Examples of this compound include a compound represented by the following formula (F). Incidentally, the compound represented by the following formula (F) exhibits an effective basicity in the system as by the action of an acid.

In formula (F), each Ra independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. Also, when n=2, two Ra may be the same or different, and two Ra may combine with each other to form a divalent heterocyclic hydrocarbon group (preferably having a carbon number of 20 or less) or a derivative thereof.

Each Rb independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, provided that in -C(Rb)(Rb)(Rb), when one or more Rb are a hydrogen atom, at least one of remaining Rb is a cyclopropyl group or a 1- alkoxyalkyl group.

At least two Rb may combine to form an alicyclic hydrocarbon group, an aromatic hydrocarbon group, a heterocyclic hydrocarbon group, or a derivative thereof. n represents an integer of 0 to 2, m represents an integer of 1 to 3, and n+m=3.

In formula (F), each of the alkyl group, cycloalkyl group, aryl group and aralkyl group represented by Ra and Rb may be substituted with a functional group such as hydroxyl group, cyano group, amino group, pyrrolidino group, piperidino group, morpholino group and oxo group, an alkoxy group, or a halogen atom.

Examples of the alkyl group, cycloalkyl group, aryl group and aralkyl group (each of these alkyl, cycloalkyl, aryl and aralkyl groups may be substituted with the above-described functional group, an alkoxy group or a halogen atom) of R include:

a group derived from a linear or branched alkane such as methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane and dodecane, or a group where the group derived from an alkane is substituted with one or more kinds of or one or more groups of cycloalkyl group such as cyclobutyl group, cyclopentyl group and cyclohexyl group;

a group derived from a cycloalkane such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, norbornane, adamantane and noradamantane, or a group where the group derived from a cycloalkane is substituted with one or more kinds of or one or more groups of linear or branched alkyl group such as methyl group, ethyl group, n-propyl group, i- propyl group, n-butyl group, 2-methylpropyl group, 1 -methylpropyl group and tert-butyl group;

a group derived from an aromatic compound such as benzene, naphthalene and anthracene, or a group where the group derived from an aromatic compound is substituted with one or more kinds of or one or more groups of linear or branched alkyl group such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1 -methylpropyl group and tert-butyl group;

a group derived from a heterocyclic compound such as pyrrolidine, piperidine, morpholine, tetrahydrofuran, tetrahydropyran, indole, indoline, quinoline, perhydroquinoline, indazole and benzimidazole, or a group where the group derived from a heterocyclic compound is substituted with one or more kinds of or one or more groups of linear or branched alkyl group or aromatic compound-derived group; a group where the group derived from a linear or branched alkane or the group derived from a cycloalkane is substituted with one or more kinds of or one or more groups of aromatic compound-derived group such as phenyl group, naphthyl group and anthracenyl group; and a group where the substituent above is substituted with a functional group such as hydroxyl group, cyano group, amino group, pyrrolidino group, piperidino group, morpholino group and oxo group.

Examples of the divalent heterocyclic hydrocarbon group (preferably having a carbon number of 1 to 20) formed by combining Ra with each other or a derivative thereof include a group derived from a heterocyclic compound such as pyrrolidine, piperidine, morpholine, 1,4,5,6-tetrahydropyrimidine, 1,2,3,4-tetrahydroquinoline, 1,2,3,6- tetrahydropyridine, homopiperazine, 4-azabenzimidazole, benzotriazole, 5-azabenzotriazole, lH-l,2,3-triazole, 1 ,4,7-triazacyclononane, tetrazole, 7-azaindole, indazole, benzimidazole, imidazo[l,2-a]pyridine, (l S,4S)-(+)-2,5-diazabicyclo[2.2.1]heptane, 1 ,5,7- triazabicyclo[4.4.0]dec-5-ene, indole, indoline, 1,2,3,4-tetrahydroquinoxaline, perhydroquinoline and 1,5,9-triazacyclododecane, and a group where the group derived from a heterocyclic compound is substituted with one or more kinds of or one or more groups of linear or branched alkane-derived group, cycloalkane-derived group, aromatic compound- derived group, heterocyclic compound-derived group, and functional group such as hydroxyl group, cyano group, amino group, pyrrolidino group, piperidino group, morpholino group and oxo group.

Specific examples of the compound represented by formula (F) are illustrated below.

D-45) (D^6) (D-47)

(D-52) (D-53) (D-54) (D-55)

As for the compound represented by formula (F), a commercially available product may be used, or the compound may be synthesized from a commercially available amine by the method described, for example, in Protective Groups in Organic Synthesis, 4th edition. As a most general method, the compound can be synthesized in accordance with the method described, for example, in JP-A-2009- 199021.

As the basic compound (Ν'), a compound having an amine oxide structure may be also used. Specific examples of the compound which can be used include triethylaminepyridine N-oxide, tributylamine N-oxide, triethanolamine N-oxide, tris(methoxyethyl)amine N-oxide, tris(2-(methoxymethoxy)ethyl)amine=oxide, 2,2', 2"- nitrilotriethylpropionate N-oxide, N-2-(2-methoxyethoxy)methoxyethylmorpholine N-oxide, and amine oxide compounds exemplified in JP-A-2008-102383.

The molecular weight of the basic compound (Ν') is preferably from 250 to 2,000, more preferably from 400 to 1,000. In view of more reduction of LWR and uniformity of local pattern dimension, the molecular weight of the basic compound is preferably 400 or more, more preferably 500 or more, still more preferably 600 or more.

Such a basic compound (Ν') may be used in combination with the compound (N), and one basic compound is used alone, or two or more basic compounds are used in combination.

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may or may not contain the basic compound (N¹), but in the case of containing the basic compound (Ν'), the amount used thereof is usually from 0.001 to 10 mass%, preferably from 0.01 to 5 mass%, based on the solid content of the actinic ray-sensitive or radiation- sensitive resin composition.

[6] (E) Solvent

Examples of the solvent which can be used at the preparation of the actinic ray- sensitive or radiation-sensitive resin composition of the present invention include an organic solvent such as alkylene glycol monoalkyl ether carboxylate, alkylene glycol monoalkyl ether, alkyl lactate ester, alkyl alkoxypropionate, cyclic lactone (preferably having a carbon number of 4 to 10), monoketone compound (preferably having a carbon number of 4 to 10) which may have a ring, alkylene carbonate, alkyl alkoxyacetate and alkyl pyruvate.

Specific examples of such a solvent include those recited in paragraphs [0441] to [0455] of U.S. Patent Application Publication No. 2008/0187860.

In the present invention, a mixed solvent prepared by mixing a solvent containing a hydroxyl group in the structure and a solvent not containing a hydroxyl group may be used as the organic solvent.

The solvent containing a hydroxyl group and the solvent not containing a hydroxyl group may be appropriately selected from the compounds exemplified above, but the solvent containing a hydroxyl group is preferably an alkylene glycol monoalkyl ether, an alkyl lactate or the like, more preferably propylene glycol monomethyl ether (PGME, another name: 1- methoxy-2-propanol) or ethyl lactate. The solvent not containing a hydroxyl group is preferably an alkylene glycol monoalkyl ether acetate, an alkyl alkoxypropionate, a monoketone compound which may contain a ring, a cyclic lactone, an alkyl acetate or the like, more preferably propylene glycol monomethyl ether acetate (PGMEA, another name: 1- methoxy-2-acetoxypropane), ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone or butyl acetate, and most preferably propylene glycol monomethyl ether acetate, ethyl ethoxypropionate or 2-heptanone.

The mixing ratio (by mass) of the solvent containing a hydroxyl group to the solvent not containing a hydroxyl group is from 1/99 to 99/1, preferably from 10/90 to 90/10, more preferably from 20/80 to 60/40. A mixed solvent in which the solvent not containing a hydroxyl group is contained in a ratio of 50 mass% or more is particularly preferred in view of coating uniformity.

The solvent preferably contains propylene glycol monomethyl ether acetate and is preferably a solvent composed of propylene glycol monomethyl ether acetate alone or a mixed solvent of two or more kinds of solvents containing propylene glycol monomethyl ether acetate.

[7] (F) Surfactant

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may or may not further contain a surfactant, but in the case of containing a surfactant, it is preferred to contain any one of fluorine-containing and/or silicon-containing surfactants (a fluorine-containing surfactant, a silicon-containing surfactant and a surfactant containing both a fluorine atom and a silicon atom), or two or more thereof.

By containing the surfactant, the actinic ray-sensitive or radiation-sensitive resin composition of the present invention can give a resist pattern improved in the sensitivity, resolution and adherence and reduced in the development defect at the time of using an exposure light source having a wavelength of 250 nm or less, particularly 220 nm or less.

The fluorine-containing and/or silicon-containing surfactants include the surfactants described in paragraph [0276] of U.S. Patent Application Publication No. 2008/0248425, and examples thereof include EFtop EF301 and EF303 (produced by Shin-Akita Kasei K.K.); Florad FC430, 431 and 4430 (produced by Sumitomo 3M Inc.); Megaface F171, F173, F176, F189, Fl 13, Fl 10, F177, F120 and R08 (produced by DIC Corp.); Surflon S-382, SCI 01, 102, 103, 104, 105 and 106, and KH-20 (produced by Asahi Glass Co., Ltd.); Troysol S-366 (produced by Troy Chemical); GF-300 and GF-150 (produced by Toagosei Chemical Industry Co., Ltd.); Surflon S-393 (produced by Seimi Chemical Co., Ltd.); EFtop EF121, EF122A, EF122B, RF122C, EF125M, EF135M, EF351, EF352, EF801, EF802 and EF601 (produced by JEMCO Inc.); PF636, PF656, PF6320 and PF6520 (produced by OMNOVA); and FTX- 204G, 208G, 218G, 230G, 204D, 208D, 212D, 218D and 222D (produced by NEOS Co., Ltd.). In addition, Polysiloxane Polymer KP-341 (produced by Shin-Etsu Chemical Co., Ltd.) may be also used as the silicon-containing surfactant.

Other than those known surfactants, a surfactant using a polymer having a fluoro- aliphatic group derived from a fluoro-aliphatic compound which is produced by a telomerization process (also called a telomer process) or an oligomerization process (also called an oligomer process), may be used. The fluoro-aliphatic compound can be synthesized by the method described in JP-A-2002-90991.

Examples of the surfactant coming under the surfactant above include Megaface F178, F-470, F-473, F-475, F-476 and F-472 (produced by DIC Corp.); a copolymer of a C₆Fi3 group-containing acrylate (or methacrylate) with a (poly(oxyalkylene)) acrylate (or methacrylate); and a copolymer of a C3F7 group-containing acrylate (or methacrylate) with a (poly(oxyethylene)) acrylate (or methacrylate) and a (poly(oxypropylene)) acrylate (or methacrylate).

In the present invention, a surfactant other than the fluorine-containing and/or silicon-containing surfactants, described in paragraph [0280] of U.S. Patent Application Publication No. 2008/0248425 may be also used.

One of these surfactants may be used alone, or some of them may be used in combination.

In the case where the actinic ray-sensitive or radiation-sensitive resin composition contains a surfactant, the amount of the surfactant used is preferably from 0.0001 to 2 mass%, more preferably from 0.0005 to 1 mass%, based on the total amount of the actinic ray- sensitive or radiation-sensitive resin composition (excluding the solvent).

On the other hand, when the amount added of the surfactant is set to 10 ppm or less based on the total amount of the actinic ray-sensitive or radiation-sensitive resin composition (excluding the solvent), the hydrophobic resin is more unevenly distributed to the surface, so that the resist film surface can be made more hydrophobic and the followability of water at the immersion exposure can be enhanced. [8] (G) Other additives

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may or may not contain an onium carboxylate. Examples of the onium carboxylate include those described in paragraphs [0605] and [0606] of U.S. Patent Application Publication No. 2008/0187860.

Such an onium carboxylate can be synthesized by reacting a sulfonium hydroxide, iodonium hydroxide or ammonium hydroxide and a carboxylic acid with silver oxide in an appropriate solvent.

In the case where the actinic ray-sensitive or radiation-sensitive resin composition contains an onium carboxylate, the content thereof is generally from 0.1 to 20 mass%, preferably from 0.5 to 10 mass%, more preferably from 1 to 7 mass%, based on the total solid content of the composition.

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention may further contain, for example, a dye, a plasticizer, a photosensitizer, a light absorber, an alkali-soluble resin, a dissolution inhibitor, and a compound for accelerating dissolution in a developer (for example, a phenol compound having a molecular weight of 1 ,000 or less, or a carboxyl group-containing alicyclic or aliphatic compound), if desired.

The phenol compound having a molecular weight of 1,000 or less can be easily synthesized by one skilled in the art by referring to the method described, for example, in JP- A-4-122938, JP-A-2-28531, U.S. Patent 4,916,210 and European Patent 219294.

Specific examples of the carboxyl group-containing alicyclic or aliphatic compound include, but are not limited to, a carboxylic acid derivative having a steroid structure, such as cholic acid, deoxycholic acid and lithocholic acid, an adamantanecarboxylic acid derivative, an adamantanedicarboxylic acid, a cyclohexanecarboxylic acid, and a cyclohexanedicarboxylic acid.

From the standpoint of enhancing the resolution, the actinic ray-sensitive or radiation-sensitive resin composition of the present invention is preferably used in a film thickness of 30 to 250 nm, more preferably from 30 to 200 nm. Such a film thickness can be achieved by setting the solid content concentration in the composition to an appropriate range, thereby imparting an appropriate viscosity and enhancing the coatability and film-forming property.

The solid content concentration of the actinic ray-sensitive or radiation-sensitive resin composition of the present invention is usually from 1.0 to 10 mass%, preferably from 2.0 to 5.7 mass%, more preferably from 2.0 to 5.3 mass%. By setting the solid content concentration to the range above, the resist solution can be uniformly coated on a substrate and furthermore, a resist pattern improved in the line width roughness can be formed. The reason therefor is not clearly known, but it is considered that thanks to a solid content concentration of 10 mass% or less, preferably 5.7 mass% or less, aggregation of materials, particularly a photoacid generator, in the resist solution is suppressed, as a result, a uniform resist film can be formed.

The solid content concentration is a weight percentage of the weight of resist components excluding the solvent, based on the total weight of the actinic ray-sensitive or radiation-sensitive resin composition.

The actinic ray-sensitive or radiation-sensitive resin composition of the present invention is used by dissolving the components above in a predetermined organic solvent, preferably in the above-described mixed solvent, filtering the solution through a filter, and coating the filtrate on a predetermined support (substrate). The filter used for filtration is preferably a polytetrafluoroethylene-, polyethylene- or nylon-made filter having a pore size of 0.1 μηι or less, more preferably 0.05 μιη or less, still more preferably 0.03 μηι or less. In the filtration through a filter, as described, for example, in JP-A-2002-62667, circulating filtration may be performed, or the filtration may be performed by connecting a plurality of kinds of filters in series or in parallel. Also, the composition may be filtered a plurality of times. Furthermore, a deaeration treatment or the like may be applied to the composition before and after filtration through a filter.

[9] Pattern forming method

The pattern forming method (negative pattern forming method) of the present invention comprises at least:

(i) a step of forming a film (resist film) from the actinic ray-sensitive or radiation-sensitive resin composition described above,

(ii) a step of exposing the film, and

(iii) a step of performing development by using an organic solvent-containing developer to form a negative pattern.

The exposure in the step (ii) may be immersion exposure.

The pattern forming method of the present invention preferably has (iv) a heating step after the exposure step (ii). The pattern forming method of the present invention may further have (v) a step of performing development by using an alkali developer.

The resist film is formed from the above-described actinic ray-sensitive or radiation- sensitive resin composition of the present invention and, more specifically, is preferably formed on a substrate. In the pattern forming method of the present invention, the step of forming a film on a substrate by using the actinic ray-sensitive or radiation-sensitive resin composition, the step of exposing the film, and the development step can be performed by generally known methods.

It is also preferred to include, after film formation, a preheating step (PB; Prebake) before entering the exposure step.

Furthermore, it is also preferred to include a post-exposure heating step (PEB; Post Exposure Bake) after the exposure step but before the development step.

As for the heating temperature, both PB and PEB are preferably performed at 70 to 130°C, more preferably at 80 to 120°C.

The heating time is preferably from 30 to 300 seconds, more preferably from 30 to 180 seconds, still more preferably from 30 to 90 seconds.

The heating can be performed using a device attached to an ordinary exposure/developing machine or may be performed using a hot plate or the like.

Thanks to baking, the reaction in the exposed area is accelerated, and the sensitivity and pattern profile are improved.

The light source of the exposure apparatus for use in the present invention is not particularly limited in its wavelength but includes, for example, infrared light, visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light, X-ray and electron beam and is preferably far ultraviolet light having a wavelength of 250 nm or less, more preferably 220 nra or less, still more preferably from 1 to 200 nm. Specific examples thereof include KrF excimer laser (248 nm), ArF excimer laser (193 nm), F₂ excimer laser (157 nm), X-ray, EUV (13 nm) and electron beam. Among these, KrF excimer laser, ArF excimer laser, EUV and electron beam are preferred, and ArF excimer laser is more preferred.

In the present invention, an immersion exposure method can be applied in the step of performing exposure.

The immersion exposure method is a technique to increase the resolution, and this is a technique of performing the exposure by filling the space between a projection lens and a sample with a high refractive-index liquid (hereinafter, sometimes referred to as "immersion liquid").

As for the "effect of immersion", assuming that λ₀ is the wavelength of exposure light in air, n is the refractive index of the immersion liquid with respect to air, Θ is the convergence half-angle of beam and NA₀=sin Θ, the resolution and the depth of focus in immersion can be expressed by the following formulae. Here, k_\ and k₂ are coefficients related to the process.

(Resolution) = ki^«( ₀/n)/NA₀

(Depth of focus) - ±k₂ ^«( ₀/n)/NA₀ ²

That is, the effect of immersion is equal to use of an exposure wavelength of 1/n. In other words, in the case of a projection optical system having the same NA, the depth of focus can be made n times larger by the immersion. This is effective for all pattern profiles and furthermore, can be combined with the super-resolution technology under study at present, such as phase-shift method and modified illumination method.

In the case of performing immersion exposure, a step of washing the film surface with an aqueous chemical solution may be performed (1) after forming a film on a substrate but before the step of exposing the film and/or (2) after the step of exposing the film through an immersion liquid but before the step of heating the film.

The immersion liquid is preferably a liquid being transparent to light at the exposure wavelength and having as small a temperature coefficient of refractive index as possible in order to minimize the distortion of an optical image projected on the film. Particularly, when the exposure light source is ArF excimer laser (wavelength: 193 nm), water is preferably used in view of easy availability and easy handleability in addition to the above-described aspects.

In the case of using water, an additive (liquid) capable of decreasing the surface tension of water and increasing the interface activity may be added in a small ratio. This additive is preferably an additive that does not dissolve the resist layer on the wafer and at the same time, gives only a negligible effect on the optical coat at the undersurface of the lens element. Such an additive is preferably, for example, an aliphatic alcohol having a refractive index substantially equal to that of water, and specific examples thereof include methyl alcohol, ethyl alcohol and isopropyl alcohol. By virtue of adding an alcohol having a refractive index substantially equal to that of water, even when the alcohol component in water is evaporated and its content concentration is changed, the change in the refractive index of the liquid as a whole can be advantageously made very small.

On the other hand, if a substance opaque to light at 193 nm or an impurity greatly differing in the refractive index from water is mingled, this incurs distortion of the optical image projected on the resist. Therefore, the water used is preferably distilled water. Furthermore, pure water after filtration through an ion exchange filter or the like may be also used.

The electrical resistance of water used as the immersion liquid is preferably 18.3 MQcm or more, and TOC (total organic carbon) is preferably 20 ppb or less. The water is preferably subjected to a deaeration treatment.

Also, the lithography performance can be enhanced by raising the refractive index of the immersion liquid. From such a standpoint, an additive for raising the refractive index may be added to water, or heavy water (D₂0) may be used in place of water.

In the case where the film formed using the composition of the present invention is exposed through an immersion medium, the above-described hydrophobic resin (D) may be further added, if desired. The receding contact angle on the surface is increased by the addition of the hydrophobic resin (D). The receding contact angle of the film is preferably from 60 to 90°, more preferably 70° or more.

In the immersion exposure step, the immersion liquid must move on a wafer following the movement of an exposure head that is scanning the wafer at a high speed to form an exposure pattern. Therefore, the contact angle of the immersion liquid for the resist film in a dynamic state is important, and the resist is required to have a performance allowing the immersion liquid to follow the high-speed scanning of an exposure head with no remaining of a liquid droplet.

In order to prevent the film from directly contacting with the immersion liquid, a film (hereinafter, sometimes referred to as a "topcoat") sparingly soluble in the immersion liquid may be provided between the film formed using the composition of the present invention and the immersion liquid. The functions required of the topcoat are suitability for coating as a resist overlayer, transparency to radiation, particularly radiation having a wavelength of 193 nm, and sparing solubility in immersion liquid. The topcoat is preferably unmixable with the resist and uniformly coatable as a resist overlayer.

In view of transparency to light at 193 nm, the topcoat is preferably an aromatic-free polymer.

Specific examples thereof include a hydrocarbon polymer, an acrylic acid ester polymer, a polymethacrylic acid, a polyacrylic acid, a polyvinyl ether, a silicon-containing polymer, and a fluorine-containing polymer. The above-described hydrophobic resin (D) is suitable also as the topcoat. If impurities are dissolved out into the immersion liquid from the topcoat, the optical lens is contaminated. For this reason, residual monomer components of the polymer are preferably little contained in the topcoat.

On removing the topcoat, a developer may be used, or a release agent may be separately used. The release agent is preferably a solvent less that is likely to permeate the film. From the standpoint that the removing step can be performed simultaneously with the development step of the film, the topcoat is preferably removable with an alkali developer and in view of removal with an alkali developer, the topcoat is preferably acidic, but in consideration of non-intermixing with the film, the topcoat may be neutral or alkaline.

The difference in the refractive index between the topcoat and the immersion liquid is preferably null or small. In this case, the resolution can be enhanced. In the case where the exposure light source is ArF excimer laser (wavelength: 193 nm), water is preferably used as the immersion liquid and therefore, the topcoat for ArF immersion exposure preferably has a refractive index close to the refractive index (1.44) of water. Also, in view of transparency and refractive index, the topcoat is preferably a thin film.

The topcoat is preferably unmixable with the film and further unmixable also with the immersion liquid. From this standpoint, when the immersion liquid is water, the solvent used for the topcoat is preferably a medium that is sparingly soluble in the solvent used for the composition of the present invention and is insoluble in water. Furthermore, when the immersion liquid is an organic solvent, the topcoat may be either water-soluble or water- insoluble.

In the present invention, the substrate on which the film is formed is not particularly limited, and an inorganic substrate such as silicon, SiN, Si0₂ and SiN, a coating-type inorganic substrate such as SOG, or a substrate generally used in the process of producing a semiconductor such as IC or producing a liquid crystal device or a circuit board such as thermal head or in the lithography of other photo-fabrication processes, can be used. If desired, an organic antireflection film may be formed between the film and the substrate.

In the case where the pattern forming method of the present invention further includes a step of performing development by using an alkali developer, examples of the alkali developer which can be used include an alkaline aqueous solution of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate and aqueous ammonia, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, or cyclic amines such as pyrrole and piperidine.

This alkaline aqueous solution may be also used after adding thereto alcohols and a surfactant each in an appropriate amount.

The alkali concentration of the alkali developer is usually from 0.1 to 20 mass%.

The pH of the alkali developer is usually from 10.0 to 15.0.

In particular, an aqueous 2.38 mass% tetramethylammonium hydroxide solution is preferred.

As for the rinsing solution in the rinsing treatment performed after the alkali development, pure water is used, and the pure water may be used after adding thereto an appropriate amount of a surfactant.

After the development or rinsing, a treatment of removing the developer or rinsing solution adhering on the pattern by a supercritical fluid may be performed.

As for the developer which can be used in the step of performing development by using an organic solvent-containing developer to form a negative pattern (hereinafter, sometimes referred to as an "organic developer"), a polar solvent such as ketone-based solvent, ester-based solvent, alcohol-based solvent, amide-based solvent and ether-based solvent, or a hydrocarbon-based solvent can be used.

Examples of the ketone-based solvent include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone (methyl amyl ketone), 4-heptanone, 1-hexanone, 2- hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetyl acetone, acetonyl acetone, ionone, diacetonyl alcohol, acetyl carbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate.

Examples of the ester-based solvent include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, pentyl acetate, isopentyl acetate, amyl acetate, cyclohexyl acetate, isobutyl isobutyrate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, and propyl lactate.

Examples of the alcohol-based solvent include an alcohol such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol and n-decanol; a glycol-based solvent such as ethylene glycol, diethylene glycol and triethylene glycol; and a glycol ether-based solvent such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether and methoxymethyl butanol.

Examples of the ether-based solvent include dioxane, tetrahydrofuran, phenetole and dibutyl ether, in addition to the glycol ether-based solvents above.

Examples of the amide-based solvent which can be used include N-methyl-2- pyrrolidone, N,N-dimethylacetamide, Ν,Ν-dimethylformamide, hexamethylphosphoric triamide, and l,3-dimethyl-2-imidazolidinone.

Examples of the hydrocarbon-based solvent include an aromatic hydrocarbon-based solvent such as toluene and xylene, and an aliphatic hydrocarbon-based solvent such as pentane, hexane, octane and decane.

A plurality of these solvents may be mixed, or the solvent may be used by mixing it with a solvent other than those described above or with water. However, in order to sufficiently bring out the effects of the present invention, the water content percentage in the entire developer is preferably less than 10 mass%, and it is more preferred to contain substantially no water.

That is, the amount of the organic solvent used in the organic developer is preferably from 90 to 100 mass%, more preferably from 95 to 100 mass%, based on the total amount of the developer.

In particular, the organic developer is preferably a developer containing at least one kind of an organic solvent selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, an amide-based solvent and an ether-based solvent.

The vapor pressure at 20°C of the organic developer is preferably 5 kPa or less, more preferably 3 kPa or less, still more preferably 2 kPa or less. By setting the vapor pressure of the organic developer to 5 kPa or less, evaporation of the developer on a substrate or in a development cup is suppressed and the temperature uniformity in the wafer plane is enhanced, as a result, the dimensional uniformity in the wafer plane is improved.

Specific examples of the solvent having a vapor pressure of 5 kPa or less include a ketone-based solvent such as 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, 2-heptanone (methyl amyl ketone), 4-heptanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone and methyl isobutyl ketone; an ester-based solvent such as butyl acetate, pentyl acetate, isopentyl acetate, amyl acetate, cyclohexyl acetate, isobutyl isobutyrate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl formate, propyl formate, ethyl lactate, butyl lactate and propyl lactate; an alcohol-based solvent such as n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert- butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol and n- decanol; a glycol-based solvent such as ethylene glycol, diethylene glycol and triethylene glycol; a glycol ether-based solvent such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether and methoxymethylbutanol; an ether-based solvent such as tetrahydrofuran, phenetole and dibutyl ether; an amide-based solvent such as N-methyl-2-pyrrolidone, Ν,Ν-dimethylacetamide and Ν,Ν-dimethylformamide; an aromatic hydrocarbon-based solvent such as toluene and xylene; and an aliphatic hydrocarbon-based solvent such as octane and decane.

Specific examples of the solvent having a vapor pressure of 2 kPa or less that is a particularly preferred range include a ketone-based solvent such as 1 -octanone, 2-octanone, 1 - nonanone, 2-nonanone, 4-heptanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone and phenylacetone; an ester-based solvent such as butyl acetate, amyl acetate, cyclohexyl acetate, isobutyl isobutyrate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl- 3-methoxybutyl acetate, ethyl lactate, butyl lactate and propyl lactate; an alcohol-based solvent such as n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol and n-decanol; a glycol-based solvent such as ethylene glycol, diethylene glycol and triethylene glycol; a glycol ether-based solvent such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether and methoxymethylbutanol; an ether-based solvent such as phenetole and dibutyl ether; an amide-based solvent such as N-methyl-2-pyrrolidone, N,N- dimethylacetamide and Ν,Ν-dimethylformamide; an aromatic hydrocarbon-based solvent such as xylene; and an aliphatic hydrocarbon-based solvent such as octane and decane.

In the organic developer, an appropriate amount of a surfactant can be added, if desired.

The surfactant is not particularly limited but, for example, ionic or nonionic fluorine-containing and/or silicon-containing surfactants can be used. Examples of the fluorine-containing and/or silicon-containing surfactants include surfactants described in JP- A-62-36663, JP-A-61-226746, JP-A-61 -226745, JP-A-62- 170950, JP-A-63-34540, JP-A-7- 230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988 and U.S. Patents 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511 and 5,824,451. A nonionic surfactant is preferred. The nonionic surfactant is not particularly limited, but use of a fluorine- containing surfactant or a silicon-containing surfactant is more preferred.

The amount of the surfactant used is usually from 0.001 to 5 mass%, preferably from 0.005 to 2 mass%, more preferably from 0.01 to 0.5 mass%, based on the total amount of the developer.

As regards the developing method, for example, a method of dipping the substrate in a bath filled with the developer for a fixed time (dipping method), a method of raising the developer on the substrate surface by the effect of a surface tension and keeping it still for a fixed time, thereby performing the development (puddling method), a method of spraying the developer on the substrate surface (spraying method), and a method of continuously ejecting the developer on the substrate spinning at a constant speed while scanning with a developer ejecting nozzle at a constant rate (dynamic dispense method) may be applied.

In the case where the above-described various developing methods include a step of ejecting the developer toward the resist film from a development nozzle of a developing apparatus, the ejection pressure of the developer ejected (the flow velocity per unit area of the developer ejected) is preferably 2 mL/sec/mm² or less, more preferably 1.5 mL/sec/mm² or less, still more preferably 1 mL/sec/mm or less. The flow velocity has no particular lower limit but in view of throughput, is preferably 0.2 mL/sec/mm² or more.

By setting the ejection pressure of the ejected developer to the range above, pattern defects attributable to the resist scum after development can be greatly reduced.

Details of this mechanism are not clearly known, but it is considered that thanks to the ejection pressure in the above-described range, the pressure imposed on the resist film by the developer becomes small and the resist film or resist pattern is kept from inadvertent chipping or collapse.

Here, the ejection pressure (mL/sec/mm ) of the developer is a value at the outlet of a development nozzle in a developing apparatus.

Examples of the method for adjusting the ejection pressure of the developer include a method of adjusting the ejection pressure by a pump or the like, and a method of supplying the developer from a pressurized tank and adjusting the pressure to change the ejection pressure.

After the step of performing development by using an organic solvent-containing developer, a step of stopping the development while replacing the solvent with another solvent may be practiced.

The pattern forming method preferably includes a step of rinsing the film by using a rinsing solution, after the step of performing development by using an organic solvent- containing developer.

The rinsing solution used in the rinsing step after the step of performing development by using an organic solvent-containing developer is not particularly limited as long as it does not dissolve the resist pattern, and a solution containing a general organic solvent may be used. The rinsing solution used is preferably a rinsing solution containing at least one kind of an organic solvent selected from the group consisting of a hydrocarbon-based solvent, a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, an amide- based solvent and an ether-based solvent.

Specific examples of the hydrocarbon-based solvent, ketone-based solvent, ester- based solvent, alcohol-based solvent, amide-based solvent and ether-based solvent, are the same as those described above for the organic solvent-containing developer.

After the step of performing development by using an organic solvent-containing developer, more preferably, a step of rinsing the film by using a rinsing solution containing at least one kind of an organic solvent selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent and an amide-based solvent is preformed; still more preferably, a step of rinsing the film by using a rinsing solution containing an alcohol-based solvent or an ester-based solvent is performed; yet still more preferably, a step of rinsing the film by using a rinsing solution containing a monohydric alcohol is performed; and most preferably, a step of rinsing the film by using a rinsing solution containing a monohydric alcohol having a carbon number of 5 or more is performed.

The monohydric alcohol used in the rinsing step includes a linear, branched or cyclic monohydric alcohol, and specific examples of the monohydric alcohol which can be used include 1-butanol, 2-butanol, 3-methyl-l-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 1- hexanol, 4-methyl-2-pentanol, 1-heptanol, 1-octanol, 2-hexanol, cyclopentanol, 2-heptanol, 2- octanol, 3-hexanol, 3-heptanol, 3-octanol, and 4-octanol. As for the particularly preferred monohydric alcohol having a carbon number of 5 or more, 1-hexanol, 2-hexanol, 4-methyl-2- pentanol, 1-pentanol, 3-methyl-l-butanol and the like can be used.

A plurality of these components may be mixed, or the solvent may be used by mixing it with an organic solvent other than those described above.

The water content percentage in the rinsing solution is preferably 10 mass% or less, more preferably 5 mass% or less, still more preferably 3 mass% or less. By setting the water content percentage to 10 mass% or less, good development characteristics can be obtained.

The vapor pressure at 20°C of the rinsing solution used after the step of performing development by using an organic solvent-containing developer is preferably from 0.05 to 5 kPa, more preferably from 0.1 to 5 kPa, and most preferably from 0.12 to 3 kPa. By setting the vapor pressure of the rinsing solution to be from 0.05 to 5 kPa, the temperature uniformity in the wafer plane is enhanced and moreover, swelling due to permeation of the rinsing solution is suppressed, as a result, the dimensional uniformity in the wafer plane is improved.

The rinsing solution may be also used after adding thereto an appropriate amount of a surfactant.

In the rinsing step, the wafer subjected to development using an organic solvent- containing developer is rinsed by using the above-described organic solvent-containing rinsing solution. The method for rinsing treatment is not particularly limited, but examples of the method which can be applied include a method of continuously ejecting the rinsing solution on the substrate spinning at a constant speed (spin coating method), a method of dipping the substrate in a bath filled with the rinsing solution for a fixed time (dipping method), and a method of spraying the rinsing solution on the substrate surface (spraying method). Above all, it is preferred to perform the rinsing treatment by the spin coating method and after the rinsing, remove the rinsing solution from the substrate surface by spinning the substrate at a rotational speed of 2,000 to 4,000 rpm. It is also preferred to include a heating step (Post Bake) after the rinsing step. The developer and rinsing solution remaining between patterns and in the inside of the pattern are removed by the baking. The heating step after the rinsing step is performed at usually from 40 to 160°C, preferably from 70 to 95°C, for usually from 10 seconds to 3 minutes, preferably from 30 to 90 seconds.

The present invention also relates to an electronic device manufacturing method comprising the pattern forming method of the present invention, and an electronic device manufactured by this manufacturing method.

The electronic device of the present invention is suitably mounted on electric/electronic equipment (such as home electronic device, OA^media-related device, optical device and communication device).

Examples

(Synthesis of Resin (P-l))

In a nitrogen stream, a three-neck flask was charged with 63.4 g of cyclohexanone and heated at 80°C. Subsequently, Monomer 1 (13.45 g), Monomer 2 (17.35 g) and Monomer 3 (1.18 g) shown below were dissolved in cyclohexanone (1 17.80 g) to prepare a monomer solution. Furthermore, 0.69 g (2.0 mol% based on the total amount of monomers) of polymerization initiator V-601 (produced by Wako Pure Chemical Industries, Ltd.) was added and dissolved, and the resulting solution was added dropwise to the flask above over 6 hours. After the completion of dropwise addition, the reaction was further allowed to proceed at 80°C for 2 hours. The reaction solution was left standing to cool and then added dropwise to a mixed solvent of methanol/water=l,343.3 g/149.3 g, and the powder precipitated was collected by filtration and dried, as a result, 25.9 g of Resin (P-l) was obtained. The mass average molecular weight of Resin (P-l) was 18,900 in terms of standard polystyrene, the polydispersity (Mw/Mn) was 1.59, and the compositional ratio (molar ratio) as determined from ¹³C-NMR was 40/55/5.

Monomer 1 Monomer 2 Monomer 3

Resins (P-2) to (P-6) and (P-l 1) were synthesized in the same manner as Resin (P-l).

(Synthesis of Chain Transfer Agent 1)

A three-neck flask was charged with 13.7 g of propylene glycol monomethyl ether and after dissolving tris(3-mercaptopropionic acid)trimethylolpropane (11.96 g) and dimethylaminoethyl acrylate (8.59 g), the solution was heated at 70°C for 6 hours to obtain a 60 mass% propylene glycol monomethyl ether solution of Chain Transfer Agent 1 shown below.

Chain Transfer Agent 1

(Synthesis of Resin (P-7))

In a nitrogen stream, a three-neck flask was charged with 71.6 g of cyclohexanone and heated at 80°C. Subsequently, Monomer 4 (22.9 g), Monomer 5 (10.7 g), each shown below, and the solution of Chain Transfer Agent 1 (4.8 g, 60 mass%) were dissolved in cyclohexanone (131.1 g) to prepare a monomer solution. Furthermore, 0.34 g (1.0 mol% based on the total amount of monomers) of polymerization initiator V-601 (produced by Wako Pure Chemical Industries, Ltd.) was added and dissolved, and the resulting solution was added dropwise to the flask above over 6 hours. After the completion of dropwise addition, the reaction was further allowed to proceed at 80°C for 2 hours. The reaction solution was left standing to cool and then added dropwise to a mixed solvent of methanol/water=l,517.3 g/168.6 g, and the powder precipitated was collected by filtration and dried, as a result, 27.4 g of Resin (P-7) was obtained. The mass average molecular weight of Resin (P-7) was 9,600 in terms of standard polystyrene, the polydispersity (Mw/Mn) was 1.66, and the compositional ratio molar ratio as determined from C-NMR was 50/50.

Chain Transfer Agent 1 Monomer 4 Monomer 5

The structure, compositional ratio (molar ratio) of repeating units, mass average molecular weight and polydispersity of each of the resins synthesized are shown below.

Resins (P-8) to (P-10) were synthesized in the same manner as Resin (P-7).

(Synthesis of Resin (P-12))

In a nitrogen stream, a three-neck flask was charged with 64.3 g of cyclohexanone and heated at 75°C. Subsequently, Monomer 1 (16.7 g) and Monomer 2 (15.8 g) were dissolved in cyclohexanone (115.5 g) to prepare a monomer solution. Separately from the monomer solution above, 0.75 g (2.0 mol% based on the total amount of monomers) of polymerization initiator V-061 (produced by Wako Pure Chemical Industries, Ltd.) was dissolved in methanol (10.0 g) to prepare an initiator solution. The monomer solution and the initiator solution were simultaneously added dropwise to the flask above over 6 hours. After the completion of dropwise addition, the reaction was further allowed to proceed at 75 °C for 2 hours. The reaction solution was left standing to cool and then added dropwise to a mixed solvent of methanol/water=l,362.3 g/151.4 g, and the powder precipitated was collected by filtration and dried, as a result, 23.4 g of Resin (P-12) was obtained. The mass average molecular weight of Resin (P-12) was 18,400 in terms of standard polystyrene, the polydispersity (Mw/Mn) was 1.53, and the compositional ratio (molar ratio) as determined from ^,3C-NMR was 50/50.

The following compounds were used as the acid generator.

PAG-10 _ΡΑ&11 <Basic compound (N) whose basicity decreases upon irradiation with an actinic ray or radiation, and basic compound (N')>

The following compounds were used as a basic compound whose basicity decreases upon irradiation with an actinic ray or radiation, or a basic compound.

As the hydrophobic resin, a resin appropriately selected from Resins (HR-1) to (HR- 65), (C-l) to (C-28) and (D-l) to (D-16) was used.

As the surfactant, the followings were used.

W-l : Megaface F176 (produced by DIC Corp.; fluorine-containing)

W-2: Megaface R08 (produced by DIC Corp.; containing fluorine and silicon)

W-3: Polysiloxane Polymer KP-341 (produced by Shin-Etsu Chemical Co., Ltd.; silicon- containing)

W-4: Troysol S-366 (produced by Troy Chemical)

W-5: KH-20 (produced by Asahi Glass Co., Ltd.)

W-6: PolyFox PF-6320 (produced by OMNOVA Solutions Inc.; fluorine-containing)

As the solvent, the followings were used.

(Group a)

SL-1 : Propylene glycol monomethyl ether acetate (PGMEA)

SL-2: Propylene glycol monomethyl ether propionate

SL-3: 2-Heptanone

(Group b)

SL-4: Ethyl lactate

SL-5: Propylene glycol monomethyl ether (PGME)

SL-6: Cyclohexanone (Group c)

SL-7: γ-Butyrolactone

SL-8: Propylene carbonate

As the developer, the followings were used

SG-1 2-Nonanone

SG-2 Diisobutyl ketone

SG-3 Cyclohexyl acetate

SG-4 Isobutyl isobutyrate

SG-5 Isopentyl acetate

SG-6 Phenetole

SG-7 Dibutyl ether

SG-8 Butyl acetate

As the rinsing solution, the followings were used.

SR- 1 : 4-Methyl-2-pentanol

SR-2: 1-Hexanol

[Examples 1 to 15 and Comparative Example 1]

(Preparation of Resist)

The components shown in Table 4 below were dissolved in the solvent shown in the same Table to give a total solid content of 3.8 mass%, and the obtained solution was filtered through a polyethylene filter having a pore size of 0.03 μπι to prepare an actinic ray-sensitive or radiation-sensitive resin composition (resist composition). An organic antireflection film, ARC29SR (produced by Nissan Chemical Industries, Ltd.), was coated on a silicon wafer (12 inch, 300 ηιηιφ) and baked at 205°C for 60 seconds to form an antireflection film having a thickness of 95 nm, and the actinic ray-sensitive or radiation-sensitive resin composition was coated thereon and baked (PB: Prebake) at 100°C over 60 seconds to form a resist film having a thickness of 100 nm.

The obtained wafer was patternwise exposed through a square-array halftone mask having a hole portion of 60 nm and a hole-to-hole pitch of 90 nm (here, because of negative image formation, the portions corresponding to holes were light-shielded) by using an ArF excimer laser immersion scanner (XT1700i, manufactured by ASML, NA: 1.20, C-Quad, outer sigma: 0.900, inner sigma: 0.812, XY deflection). As the immersion liquid, ultrapure water was used. Thereafter, the resist film was heated at 105°C for 60 seconds (PEB: Post Exposure Bake), developed by puddling the organic solvent-based developer shown in Table 4 below for 30 seconds, and then rinsed by puddling the rising solution shown in Table 4 below for 30 seconds while spinning the wafer at a rotational speed of 1 ,000 rpm. Subsequently, the wafer was spun at a rotational speed of 4,000 rpm for 30 seconds, whereby a contact hole pattern having a hole diameter of 45 nm was obtained.

[Exposure Latitude (EL, %)]

The hole size was observed by a critical dimension scanning electron microscope (SEM, S-9380II, manufactured by Hitachi, Ltd.), and the optimum exposure dose when resolving a contact hole pattern with hole portions having an average size of 45 nm was taken as the sensitivity (E_opt) (mJ/cm ). Based on the determined optimum exposure dose (E_opt), the exposure dose when giving a target hole size value 45 nm±10% (that is, 40.5 nm and 49.5 nm) was determined. Thereafter, the exposure latitude (EL, %) defined by the following formula was calculated. As the value of EL is larger, the performance change due to change in the exposure dose is smaller and this is better.

[EL (%)]={ [(exposure dose when the hole portion becomes 40.5 nm)-(exposure dose when the hole portion becomes 49.5 nm)]/E_opt}xl00

[Local Pattern Dimension Uniformity (Local CDU, nm)]

Within one shot exposed at the optimum exposure dose determined in the evaluation of exposure latitude, arbitrary 25 holes in each of 20 regions spaced apart by a gap of 1 μηι (that is, 500 holes in total) were measured for the hole size. The standard deviation thereof was determined, and 3σ was computed therefrom. A smaller value indicates less dimensional variation and higher performance.

[Pre-Bridge Dimension]

An organic antireflection film, ARC29SR (produced by Nissan Chemical Industries, Ltd.), was coated on a silicon wafer and baked at 205°C for 60 seconds to form an antireflection film having a thickness of 95 nm, and the resist composition was coated thereon and baked at 100°C for 60 seconds to form a resist film having a thickness of 100 nm. The obtained wafer was patternwise exposed through an exposure mask (line/space = 1/1) by using an ArF excimer laser immersion scanner (ΧΤ1700Ϊ, manufactured by ASML, NA: 1.20, C- Quad, outer sigma: 0.981, inner sigma: 0.895, XY deflection). As the immersion liquid, ultrapure water was used. Thereafter, the resist film was heated at 100°C for 60 seconds, developed by puddling a developer for 30 seconds, rinsed by puddling a rising solution for 4 seconds, and after spinning the wafer at a rotational speed of 4,000 rpm for 30 seconds, baked at 90°C for 60 seconds to obtain a 1 : 1 line-and-space resist pattern with a pitch of 100 nm.

The 1 : 1 line-and-space resist pattern with a pitch of 100 nm was observed using a critical dimension scanning electron microscope (SEM, S-9380II, manufactured by Hitachi, Ltd.), and in the 1 :1 line-and-space resist pattern with a pitch of 100 nm at the optimum focus, the minimum space dimension below which a bridge defect is generated was observed by changing the exposure dose. A smaller value indicates that a bridge defect is less likely to be generated and the performance is higher.

Table 4

As apparent from the results in Table 4, in Comparative Example 1 where the acid- decomposable resin does not have a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity, all of exposure latitude, local pattern dimension uniformity and pre-bridge dimension performance were poor.

On the other hand, in Examples 1 to 15 using an acid-decomposable resin with a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity, an excellent result was obtained in all of exposure latitude, local pattern dimension uniformity and pre-bridge dimension performance.

Also, in Examples 1, 3, 4, 7 to 12 and 15 using an acid-decomposable resin with a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity, where the content of the repeating unit having an acid-decomposable group is 50 mol% or more based on all repeating units in the acid-decomposable resin, the local pattern dimension uniformity was more excellent.

Furthermore, in Examples 1 to 4, 6 to 13 and 15 using a composition containing, as the acid-decomposable resin, only an acid-decomposable resin with a structure containing a group having basicity or capable of decomposing by the action of an acid to increase basicity, the pre-bridge dimension performance was more excellent.

Industrial Applicability

According to the present invention, a pattern forming method capable of forming a pattern having an ultrafine space width or hole diameter (for example, 60 ran or less) in the state of the local pattern dimension uniformity, exposure latitude and pre-bridge dimension performance being excellent, an actinic ray-sensitive or radiation-sensitive resin composition used therein, a resist film, an electronic device manufacturing method using the same, and an electronic device can be provided.

This application is based on a Japanese patent application filed on April 11, 2012 (Japanese Patent Application No. 2012-90587), and the contents thereof are incorporated herein by reference.

Claims

1. A pattern forming method comprising:

(ii) a step of exposing the film, and

2. The pattern forming method as claimed in claim 1,

the resin (A) is a resin containing the repeating unit having a group capable of decomposing by the action of an acid to produce a polar group in an amount of 50 mol% or more based on all repeating units in the resin (A).

3. The pattern forming method as claimed in claim 1 or 2,

4. The pattern forming method as claimed in any one of claims 1 to 3,

5. The pattern forming method as claimed in any one of claims 1 to 3,

6. The pattern forming method as claimed in any one of claims 1 to 5,

7. The pattern forming method as claimed in any one of claims 1 to 6,

8. The pattern forming method as claimed in any one of claims 1 to 7,

9. The pattern forming method as claimed in any one of claims 1 to 8, which further comprises:

10. The pattern forming method as claimed in any one of claims 1 to 9,

wherein the exposure in the step (ii) is immersion exposure.

11. An actinic ray-sensitive or radiation-sensitive resin composition used in the pattern forming method claimed in any one of claims 1 to 10.

12. A resist film formed of the actinic ray-sensitive or radiation-sensitive resin composition claimed in claim 1 1.

13. A method for manufacturing an electronic device, comprising the pattern forming method claimed in any one of claims 1 to 10.

14. An electronic device manufactured by the manufacturing method of an electronic device claimed in claim 13.