JP2008052081A - Radiation-sensitive resin composition for liquid immersion exposure, and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the addition of an acid generator to the smallest possible amount so as to prevent the acid generator from leaching out of a resist surface under contact with an immersion liquid (water, in this case), and to prevent degradation in line-edge roughness (LER) and line-width roughness (LWR) caused by the reduction. <P>SOLUTION: This invention relates to a radiation-sensitive resin composition for liquid immersion exposure containing a resin (A) which becomes alkali-soluble under the action of an acid, a radiation-sensitive acid generator (B), a low-molecular compound (C) which becomes alkali-soluble under the action of an acid, and a solvent (D), wherein the compound (C) is represented by Formula (1), wherein R<SP>1</SP>represents an alicyclic hydrocarbon group or the like; X represents a hydroxy group, or the like; A represents a group represented by -D-COO- or the like, and D represents a methylene group, or the like. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to immersion exposure using a novel fluorine-containing polymer that can be suitably used as an immersion exposure resist used for immersion exposure in which a resist film is exposed through an immersion exposure liquid such as water. The present invention relates to a radiation sensitive resin composition.

  In the field of microfabrication represented by the manufacture of integrated circuit elements, in order to obtain a higher degree of integration, recently, lithography technology capable of microfabrication at a level of 0.10 μm or less is required. However, in the conventional lithography process, near-ultraviolet rays such as i-rays are generally used as radiation, and it is said that fine processing at a subquarter micron level is extremely difficult with this near-ultraviolet rays. Therefore, in order to enable microfabrication at a level of 0.10 μm or less, use of radiation having a shorter wavelength is being studied. Examples of such short-wavelength radiation include an emission line spectrum of a mercury lamp, far-ultraviolet rays typified by an excimer laser, an X-ray, an electron beam, and the like. ) Or ArF excimer laser (wavelength 193 nm) has been attracting attention.

  As a resist suitable for irradiation with such an excimer laser, a component having an acid-dissociable functional group and a component that generates acid upon irradiation with radiation (hereinafter referred to as “exposure”) (hereinafter referred to as “acid generator”). )) And a resist utilizing the chemical amplification effect (hereinafter referred to as “chemically amplified resist”) have been proposed. As the chemically amplified resist, for example, a resist containing a resin having a t-butyl ester group of carboxylic acid or a t-butyl carbonate group of phenol and an acid generator has been proposed. In this resist, the t-butyl ester group or t-butyl carbonate group present in the resin is dissociated by the action of an acid generated by exposure, and the resin has an acidic group composed of a carboxyl group or a phenolic hydroxyl group. As a result, the phenomenon that the exposed region of the resist film becomes readily soluble in an alkali developer is utilized.

  In such a lithography process, further fine pattern formation (for example, a fine resist pattern having a line width of about 45 nm) will be required in the future. In order to achieve such fine pattern formation of less than 45 nm, it is conceivable to shorten the light source wavelength of the exposure apparatus and increase the numerical aperture (NA) of the lens as described above. However, a new expensive exposure apparatus is required to shorten the light source wavelength. Further, when the lens has a high NA, the resolution and the depth of focus are in a trade-off relationship. Therefore, there is a problem that the depth of focus decreases even if the resolution is increased.

  Recently, a liquid immersion lithography (liquid immersion lithography) method has been reported as a lithography technique that can solve such problems. In this method, a liquid refractive index medium (immersion exposure liquid) such as pure water or a fluorine-based inert liquid having a predetermined thickness is formed on at least the resist film between the lens and the resist film on the substrate during exposure. It is to intervene. In this method, a light source having the same exposure wavelength can be used by replacing the exposure optical path space, which has conventionally been an inert gas such as air or nitrogen, with a liquid having a higher refractive index (n), such as pure water. Similar to the case of using a light source with a shorter wavelength or the case of using a high NA lens, high resolution is achieved and there is no reduction in the depth of focus. If such immersion exposure is used, it is possible to realize the formation of a resist pattern that is low in cost, excellent in high resolution, and excellent in depth of focus, using a lens mounted on an existing apparatus. It is attracting a lot of attention.

  However, in the immersion exposure process described above, the resist film directly comes into contact with an immersion exposure liquid such as water during exposure, so that the acid generator and the like are eluted from the resist film. When the amount of the eluted material is large, there are problems that the lens is damaged, a predetermined pattern shape cannot be obtained, and sufficient resolution cannot be obtained.

  Further, when water is used as the liquid for immersion exposure, there is a problem that if the receding contact angle of water in the resist film is low, the water marks are likely to remain because the water does not break during high-speed scanning exposure.

  As a resist resin used in the immersion exposure apparatus, for example, a resin described in Patent Document 1 and Patent Document 2 and an additive described in Patent Document 3 are proposed.

  However, even with resists using these resins and additives, the receding contact angle between the resist film and water is not always sufficient, and if the receding contact angle is low, the water mark remains due to poor water drainage during high-speed scanning exposure. easy. Moreover, it cannot be said that suppression of the amount of the eluate in water, such as an acid generator, is sufficient.

International Publication WO 2004/062422 JP 2005-173474 A JP 2006-48029 A

  The object of the present invention is to reduce the amount of acid generator added as much as possible in order to prevent the acid generator from eluting due to the immersion liquid (in this case water) coming into contact with the resist surface. It is an object of the present invention to provide a radiation-sensitive resin composition for immersion exposure which prevents problems that occur, deterioration of line edge roughness (LER) and line width roughness (LWR).

  According to the present invention, the following radiation sensitive resin composition for immersion exposure is provided.

[1] A resin (A) that becomes alkali-soluble by the action of an acid, a radiation-sensitive acid generator (B), a low-molecular compound (C) that becomes alkali-soluble by the action of an acid, and a solvent (D), A radiation sensitive resin composition for immersion exposure, wherein the low molecular compound (C) is represented by the following general formula (1).

(In the general formula (1), R ¹ independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ¹ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ^{1 's} are bonded to each other, together with the carbon atom to which each is bonded, 20 divalent alicyclic hydrocarbon groups or derivatives thereof, and the remaining R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent fat having 4 to 20 carbon atoms A cyclic hydrocarbon group or a derivative thereof, X is independently of each other hydrogen or a hydroxy group, at least one is a hydroxy group, A is a single bond or a group represented by -D-COO-, D is a methylene group having 2 to 4 carbon atoms Represents an alkylene group.)

[2] The radiation-sensitive acid generator (B) has a structure represented by the following general formula (2), and when the total content is 100 parts by mass of the resin (A), The radiation-sensitive resin composition for immersion exposure according to the above [1], which is 3.0 parts by mass.

(In General Formula (2), R ² is a hydrogen atom, a fluorine atom, a hydroxyl group, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkoxyl group having 1 to 10 carbon atoms. Represents a linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms, and R ³ represents a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxyl group, or a linear chain having 1 to 10 carbon atoms. , R ⁴ is independently a linear or branched alkyl group having 1 to 10 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group. Or two R ^{4 s} are bonded to each other to form a divalent group having 2 to 10 carbon atoms, the divalent group may be substituted, and Y ⁻ represents R _{^{5 C n F 2n SO 3 -}} , R SO ₃ ^- (. Wherein, ^{R 5} is a fluorine atom, or a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, n is an integer of 1 to 10), or And an anion represented by the following general formula (3-1) or (3-2), r is an integer of 0 to 8, and k is an integer of 0 to 2.)

(In each formula, R ⁶ is independently of each other a fluorine atom and a linear or branched alkyl group having 1 to 10 carbon atoms, or two R ⁶ are bonded to each other, (It is a divalent organic group having 2 to 10 carbon atoms and having a fluorine atom, and the divalent organic group may have a substituent.)

[3] The radiation-sensitive resin composition for immersion exposure according to the above [1] or [2], wherein the resin (A) contains a repeating unit containing a lactone structure.

[4] In a resist pattern forming method including immersion exposure in which radiation is irradiated between a lens and a photoresist film through an immersion exposure liquid having a refractive index at a wavelength of 193 nm higher than that of air, the photoresist film includes: A resist pattern formed using the radiation-sensitive resin composition for immersion exposure according to [1] to [3] above, wherein the formed photoresist film and the immersion exposure liquid are in direct contact with each other. Forming method.

  In the present invention, the amount of elution of the contents when the immersion liquid comes into contact with the resist film is relatively reduced by adding 0.1 to 3% by mass of an acid generator. Furthermore, the problem which arises with it, ie, the deterioration of LER and LWR, is improved by adding the low molecular weight compound (C) which becomes alkali-soluble by the action of an acid. As a result, the elution amount of the contents can be suppressed without using an upper layer film in the immersion exposure, and a radiation-sensitive resin composition having good LER and LWR can be provided.

  Hereinafter, the present invention will be described in detail.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition of the present invention is a resist pattern formed by immersion exposure in which radiation is irradiated through an immersion exposure liquid having a refractive index at a wavelength of 193 nm higher than that of air between a lens and a photoresist film. The radiation-sensitive resin composition used in the method and forming the photoresist film is a resin (A) that becomes alkali-soluble by the action of acid, a radiation-sensitive acid generator (B), and is alkali-soluble by the action of acid. The low molecular compound (C) and the solvent (D) are contained.

<Resin (A) that becomes alkali-soluble by the action of acid>
As the resin (A) that becomes alkali-soluble by the action of acid in the present invention (hereinafter also simply referred to as “resin (A)”), an alkali-insoluble or alkali-insoluble resin that becomes alkali-soluble by the action of acid is used. Is preferred. The term “alkali insoluble or alkali insoluble” as used herein refers to an alkali development condition employed when a resist pattern is formed from a resist film formed from a radiation-sensitive resin composition containing the resin (A). When a film using only the resin (A) is developed instead of the resist film, it means that 50% or more of the initial film thickness of the film remains after development.

  Examples of the resin (A) include a resin having an alicyclic skeleton such as a norbornane ring in a main chain obtained by polymerizing a norbornene derivative or the like, and a main chain obtained by copolymerizing a norbornene derivative and maleic anhydride. A resin having a norbornane ring and a maleic anhydride derivative, a resin having a norbornane ring and a (meth) acryl skeleton mixed in a main chain obtained by copolymerizing a norbornene derivative and a (meth) acrylic compound, a norbornene derivative and maleic anhydride, ( Resin in which norbornane ring, maleic anhydride derivative and (meth) acrylic skeleton are mixed in the main chain obtained by copolymerizing (meth) acrylic compound, main chain obtained by copolymerizing (meth) acrylic compound is (meth) Examples thereof include acrylic skeleton resins. In the present specification, “(meth) acryl” means one or both of “acryl” and “methacryl”.

  The resin (A) in the present invention preferably contains a repeating unit containing a group represented by the following general formula (4) (hereinafter referred to as “repeating unit (1)”).

(In the general formula (4), R ⁷ is independently a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ⁷ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ⁷ are bonded to each other, and each of the carbon atoms together with the carbon atom to which each R 4 is bonded. A divalent alicyclic hydrocarbon group having ˜20 or a derivative thereof, and the remaining R ⁷ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent having 4 to 20 carbon atoms Represents an alicyclic hydrocarbon group or a derivative thereof.)

In the general formula (4), a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms of R ⁷ and any two R ⁷ bonded to each other to form a divalent hydrocarbon having 4 to 20 carbon atoms. Examples of the alicyclic hydrocarbon group include alicyclic rings derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cycloalkanes such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. A group consisting of these alicyclic rings is, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t -The group etc. which substituted by 1 or more types or 1 or more of C1-C4 linear, branched or cyclic alkyl groups, such as a butyl group, can be mentioned. Among these alicyclic hydrocarbon groups, a group consisting of an alicyclic ring derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclopentane or cyclohexane, or a group consisting of these alicyclic rings is described above. A group substituted with an alkyl group is preferred.

  Examples of the alicyclic hydrocarbon group derivative include hydroxyl group; carboxyl group; oxo group (that is, ═O group); hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1- Hydroxypropyl groups having 1 to 4 carbon atoms such as hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkoxyl group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, a 2-methylpropoxy group, a 1-methylpropoxy group and a t-butoxy group; Group: C2-C5 such as cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, etc. A substituent such as Anoarukiru group can include one or more or one or more having groups. Of these substituents, a hydroxyl group, a carboxyl group, a hydroxymethyl group, a cyano group, a cyanomethyl group, and the like are preferable.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms of R ⁷ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methylpropyl. Group, 1-methylpropyl group, t-butyl group and the like. Of these alkyl groups, a methyl group, an ethyl group, an n-propyl group, and an i-propyl group are preferable.

  As the skeleton contained in the preferred repeating unit (1), for example, a group represented by the following formula (a), formula (b), formula (c) or formula (d) is preferable.

(In Formula (a), Formula (b), Formula (c) and Formula (d), each R ⁸ independently represents a linear or branched alkyl group having 1 to 4 carbon atoms, and m is It is an integer from 0 to 4.)

In the formula (a), the formula (b), the formula (c) and the formula (d), examples of the linear or branched alkyl group having 1 to 4 carbon atoms of R ⁸ include a methyl group, an ethyl group, Examples include n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like. Of these alkyl groups, a methyl group, an ethyl group, an n-propyl group, and an i-propyl group are preferable.

As the group represented by the formula (a), a group in which two R ^{8 s} are both methyl groups is particularly preferable. In addition, the group represented by the formula (b) is particularly preferably a group in which R ⁸ is a methyl group, an ethyl group, an n-propyl group, or an i-propyl group. The group represented by the formula (c) is particularly a group in which m is 0 and R ⁸ is a methyl group, a group in which m is 0 and R ⁸ is an ethyl group, m is 1 and R ⁸ is methyl. Preferred is a group that is a group, m is 1 and R ⁸ is an ethyl group. As the group represented by the formula (d), a group in which two R ^{8 s} are both methyl groups is particularly preferable.

  Examples of the skeleton contained in the repeating unit (1) other than the above include t-butoxycarbonyl group and groups represented by the following formulas (e-1) to (e-8).

  The main chain skeleton of the repeating unit (1) is not particularly limited, but preferably has a methacrylic acid ester, acrylic acid ester or α-trifluoroacrylic acid ester structure.

Among the monomers that give the repeating unit (1), preferred are (meth) acrylic acid 2-methyladamantyl-2-yl ester and (meth) acrylic acid 2-methyl-3-hydroxyadamantyl-2-yl. Ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyl-3-hydroxyadamantyl-2-yl ester, (meth) acrylic acid 2-n-propyladamantyl-2-yl ester Yl ester, (meth) acrylic acid 2-isopropyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2- Ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-8-methyltricyclo [5.2 1.0 ^2,6] decan-8-yl ester, (meth) ethyl-8-acrylic acid tricyclo [5.2.1.0 ^2,6] decan-8-yl ester, (meth) acrylic acid - 4-methyltetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid-4-ethyltetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tricyclo [5.2.1.0 ^2,6 ] decan-8-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tetracyclo [6.2.1 ^3,6.0 0.0 ^2,7 ] dodecane -4-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1- (3-hydroxyadamantan-1-yl) -1-methyl ethyl ester, (meth) acrylic acid 1,1-dicyclohexyl ethyl ester, (meth) acrylic acid 1,1-di (bicyclo [2.2.1] hept-2-yl) ethyl ester, Data) acrylic acid 1,1-di (tricyclo [5.2.1.0 ^2,6] decan-8-yl) ethyl ester, (meth) acrylic acid 1,1-di (tetracyclo [6.2.1 ^3,6 .0 ^2,7] dodecane-4-yl) ethyl ester, (meth) acrylic acid 1,1-di (adamantan-1-yl) ethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl Ester, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like.

  Particularly suitable monomers include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [ 2.2.1] Hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2 .1] Hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester (Meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1- Chill-1-cyclohexyl ester.

  Moreover, the resin (A) in the present invention may contain two or more of the repeating units (1).

  The resin (A) in the present invention further includes a repeating unit containing groups represented by the following general formulas (5-1) to (5-6) (hereinafter referred to as “repeating unit (2)”). It is preferable to contain.

(In the formulas (5-1) to (5-6), R ⁹ represents a hydrogen atom or an alkyl group which may have a substituent having 1 to 4 carbon atoms, and R ¹⁰ represents a hydrogen atom or M represents a methoxy group, B represents a single bond or a methylene group, E represents an oxygen atom or a methylene group, L represents an integer of 1 to 3, and p represents 0 or 1.

  The main chain skeleton of the repeating unit (2) is not particularly limited, but preferably has a methacrylic acid ester, acrylic acid ester or α-trifluoroacrylic acid ester structure.

Preferred among the monomers giving the repeating unit (2) is (meth) acrylic acid-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] non-2-yl ester. , (Meth) acrylic acid-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] non-2-yl ester, (meth) acrylic acid-5-oxo- 4-Oxa-tricyclo [5.2.1.0 ^3,8 ] dec-2-yl ester, (meth) acrylic acid-10-methoxycarbonyl-5-oxo-4-oxa-tricyclo [5.2.1 0.0 ^3,8 ] non-2-yl ester, (meth) acrylic acid-6-oxo-7-oxa-bicyclo [3.2.1] oct-2-yl ester, (meth) acrylic acid-4- Methoxycarbonyl-6-oxo- -Oxa-bicyclo [3.2.1] oct-2-yl ester, (meth) acrylic acid-7-oxo-8-oxa-bicyclo [3.3.1] oct-2-yl ester, (meth) Acrylic acid-4-methoxycarbonyl-7-oxo-8-oxabicyclo [3.3.1] oct-2-yl ester, (meth) acrylic acid-2-oxotetrahydropyran-4-yl ester, (meth ) Acrylic acid-4-methyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-ethyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-propyl- 2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2 , 2-Dimethyl-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-4,4-dimethyl-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2-oxotetrahydrofuran-3- Yl ester, (meth) acrylic acid-4,4-dimethyl-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-5,5-dimethyl-2-oxotetrahydrofuran-3-yl ester, (meth) Acrylic acid-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-5-oxotetrahydrofuran-2-ylmethyl ester, (meth) acrylic acid-3,3-dimethyl-5-oxotetrahydrofuran-2-yl Methyl ester, (meth) acrylic acid-4,4-dimethyl-5- Kiso tetrahydrofuran-2-yl methyl ester.

  The resin (A) may contain only one type of the repeating unit (2), or may contain two or more types.

  The resin (A) can further contain one or more repeating units other than the repeating unit (1) and the repeating unit (2) (hereinafter referred to as “other repeating units”).

  Other repeating units include the repeating unit of the general formula (6) (hereinafter referred to as “other repeating unit (3)”) and the repeating unit of the general formula (7) (hereinafter referred to as “other repeating unit (4)”. It is preferable to contain at least one repeating unit selected from repeating units of the general formula (8) (hereinafter referred to as “other repeating units (5)”).

(In General Formula (6), R ¹¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, and R ¹² is a polycyclic alicyclic hydrocarbon group having 7 to 20 carbon atoms. The polycyclic alicyclic hydrocarbon group of -20 is not substituted even if it is substituted with an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a cyano group, or a hydroxyalkyl group having 1 to 10 carbon atoms. May be good.)

(In General Formula (7), R ¹³ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a trifluoromethyl group, or a hydroxymethyl group, and R ¹⁴ represents a divalent organic group.)

(In General Formula (8), R ¹⁵ represents hydrogen or a methyl group, R ¹⁶ represents a single bond or a divalent organic group having 1 to 3 carbon atoms, and R ¹⁷ independently of each other represents a single bond or a carbon number. 1 to 3 represent a divalent organic group, and R ¹⁸ independently represents a hydrogen atom, a hydroxyl group, a cyano group, or a COOR ¹⁹ group (provided that R ¹⁹ is a hydrogen atom or a straight chain having 1 to 4 carbon atoms). Represents a chain-like or branched alkyl group, or an alicyclic alkyl group having 3 to 20 carbon atoms.) When at least one of the three R ¹⁸ is not a hydrogen atom and R ¹⁶ is a single bond preferably, at least one of three R ¹⁷ is a divalent organic group having 1 to 3 carbon atoms.)

R ¹² of the other repeating unit (3) represented by the general formula (6) is preferably a polycyclic alicyclic hydrocarbon group having 7 to 20 carbon atoms. Examples of such polycyclic alicyclic hydrocarbon groups include bicyclo [2.2.1] heptane (6a), bicyclo [2.2.2] octane (6b), as shown in the following formula, Tricyclo [5.2.1.0 ^2,6 ] decane (6c), tetracyclo [6.2.1.1 ^3,6 . And hydrocarbon groups composed of alicyclic rings derived from cycloalkanes such as 0 ^2,7 ] dodecane (6d) and tricyclo [3.3.1.1 ^3,7 ] decane (6e).

  These cycloalkane-derived alicyclic rings may have a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group. , 1-methylpropyl group, t-butyl group, etc. may be substituted with one or more of linear, branched or cyclic alkyl groups having 1 to 4 carbon atoms. These are represented by the following specific examples, but are not limited to those substituted by these alkyl groups, but are hydroxyl groups, cyano groups, C1-C10 hydroxyalkyl groups, carboxyls. The group may be substituted with oxygen. Moreover, these other repeating units (3) can contain 1 type (s) or 2 or more types.

Among the monomers that give other repeating units (3), (meth) acrylic acid-bicyclo [2.2.1] heptyl ester, (meth) acrylic acid-cyclohexyl ester, (meth) acrylic acid are preferred. -Bicyclo [4.4.0] decanyl ester, (meth) acrylic acid-bicyclo [2.2.2] octyl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] deca Nyl ester, (meth) acrylic acid-tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecanyl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] decanyl ester, and the like.

R ¹³ of the other repeating unit (4) represented by the general formula (7) represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a trifluoromethyl group, or a hydroxymethyl group. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, and t-butyl group. And the like.

The divalent organic group as R ¹⁴ of the other repeating unit (4) represented by the general formula (7) is preferably a divalent hydrocarbon group, and preferably a chain among the divalent hydrocarbon groups. A cyclic or cyclic hydrocarbon group is preferable, and may be an alkylene glycol group or an alkylene ester group.

Preferred R ¹⁴ is a methylene group, an ethylene group, a propylene group such as a 1,3-propylene group or a 1,2-propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, Nonamethylene group, Decamemethylene group, Undecamethylene group, Dodecamethylene group, Tridecamethylene group, Tetradecamethylene group, Pentacamethylene group, Hexadecamethylene group, Heptadecamethylene group, Octadecamethylene group, Nonadecamethylene group, Icosalen group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene group, 2-methyl- 1,4-butylene group, methylidene group, ethylidene group, propylidene group, or 2-propylidene group Saturated chain hydrocarbon groups such as den groups; cyclobutylene groups such as 1,3-cyclobutylene groups; cyclopentylene groups such as 1,3-cyclopentylene groups; cyclohexylenes such as 1,4-cyclohexylene groups A monocyclic hydrocarbon ring group such as a cycloalkylene group having 3 to 10 carbon atoms such as a cyclooctylene group such as a 1,5-cyclooctylene group; a 1,4-norbornylene group or a 2,5-norbornylene group Such as norbornylene group, 1,5-adamantylene group, adamantylene group such as 2,6-adamantylene group, etc., bridged cyclic hydrocarbon ring such as 2-4 cyclic hydrocarbon ring group having 4-30 carbon atoms Groups and the like.

Particularly when R ¹⁴ contains a divalent aliphatic cyclic hydrocarbon group, an alkylene group having 1 to 4 carbon atoms is inserted as a spacer between the bistrifluoromethyl-hydroxy-methyl group and the aliphatic cyclic hydrocarbon group. It is preferable to do.

R ¹⁴ is preferably a hydrocarbon group containing a 2,5-norbornylene group, an ethylene group, or a 1,2-propylene group.

Among the monomers giving other repeating units (4), (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester is preferable. (Meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trimethyl) Fluoromethyl-2-hydroxy-5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2 -{[5- (1 ', 1', 1'-trifluoro-2'-trifluoromethyl-2'-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester, (meth) a Acrylic acid 3 - {[8- (1 ', 1', 1'-trifluoro-2'-trifluoromethyl-2'-hydroxy) propyl] tetracyclo [6.2.1.1 ^{3, 6.} 0 ^2,7 ] dodecyl} ester and the like.

In the repeating unit (5) represented by the general formula (8), R ¹⁶ represents a single bond or a divalent organic group having 1 to 3 carbon atoms, and R ¹⁷ is a single bond or 1 to 1 carbon atoms independently of each other. 3 represents a divalent organic group, and examples of the divalent organic group having 1 to 3 carbon atoms represented by R ¹⁶ and R ¹⁷ include a methylene group, an ethylene group, and a propylene group.

R ^{19 of the} —COOR ¹⁹ group represented by R ¹⁸ in the repeating unit (5) represented by the general formula (8) is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, or An alicyclic alkyl group having 3 to 20 carbon atoms is represented.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms in R ¹⁹ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, Examples thereof include a 1-methylpropyl group and a t-butyl group. Examples of the alicyclic alkyl groups of said 3 to 20 carbon _atoms, -C _{q H 2q-1} cycloalkyl group (q is an integer of 3 to 20) represented by, for example, cyclopropyl group, cyclobutyl group , Cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group and the like, and also polycyclic alicyclic alkyl groups such as bicyclo [2.2.1] heptyl group, tricyclo [5.2.1.0 ^{2]. , 6} ] decyl group, tetracyclo [6.2.1 ^3,6 . 0 ^2,7 ] dodecanyl group, adamantyl group or the like, or one or more of linear, branched or cyclic alkyl groups, and a part of cycloalkyl group or polycyclic alicyclic alkyl group. Examples include substituted groups.

  Among the monomers that give other repeating units (5), preferred are (meth) acrylic acid 3-hydroxyadamantan-1-ylmethyl ester, (meth) acrylic acid 3,5-dihydroxyadamantane- 1-ylmethyl ester, (meth) acrylic acid 3-hydroxy-5-methyladamantan-1-yl ester, (meth) acrylic acid 3,5-dihydroxy-7-methyladamantan-1-yl ester, (meth) acrylic Acid 3-hydroxy-5,7-dimethyladamantan-1-yl ester, (meth) acrylic acid 3-hydroxy-5,7-dimethyladamantan-1-ylmethyl ester, and the like.

  As repeating units other than the above formulas (1) to (5), for example, (meth) acrylic acid esters having a bridged hydrocarbon skeleton such as dicyclopentenyl (meth) acrylate and adamantylmethyl (meth) acrylate Carboxyl group having a bridged hydrocarbon skeleton of unsaturated carboxylic acid such as carboxynorbornyl (meth) acrylate, carboxytricyclodecanyl (meth) acrylate, carboxytetracycloundecanyl (meth) acrylate Containing esters;

  Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, 2-methylpropyl (meth) acrylate, 1-methyl (meth) acrylate Propyl, t-butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, cyclopropyl (meth) acrylate, ( (Meth) acrylic acid cyclopentyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 4-methoxycyclohexyl, (meth) acrylic acid 2-cyclopentyloxycarbonylethyl, (meth) acrylic acid 2-cyclohexyloxycarbonylethyl, (meth) 2- (4-Methoxycyclohexyl) acrylic acid No bridged hydrocarbon skeleton such as aryloxycarbonyl ethyl (meth) acrylate;

  α-hydroxymethyl acrylate esters such as methyl α-hydroxymethyl acrylate, ethyl α-hydroxymethyl acrylate, n-propyl α-hydroxymethyl acrylate, n-butyl α-hydroxymethyl acrylate; (meth) acrylonitrile , Α-chloroacrylonitrile, crotonnitrile, maleinonitrile, fumaronitrile, mesacononitrile, citraconitrile, itaconnitrile, and other unsaturated nitrile compounds; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, crotonamide, maleinamide , Fumaramide, mesaconamide, citraconic amide, itaconic amide, etc .; N- (meth) acryloylmorpholine, N-vinyl-ε-caprolactam, N-vinylpyrrolidone, vinyl Other nitrogen-containing vinyl compounds such as lysine and vinylimidazole; (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, etc. Unsaturated carboxylic acids (anhydrides); 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, Carboxyl group-containing esters having no bridged hydrocarbon skeleton of unsaturated carboxylic acid such as (meth) acrylic acid 4-carboxycyclohexyl;

  1,2-adamantanediol di (meth) acrylate, 1,3-adamantanediol di (meth) acrylate, 1,4-adamantanediol di (meth) acrylate, tricyclodecanyl dimethylol di (meth) acrylate, etc. A polyfunctional monomer having a bridged hydrocarbon skeleton;

  Styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxystyrene, 2-hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene, 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene 4-methyl-3-hydroxystyrene, 5-methyl-3-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3-methyl-4-hydroxystyrene, 3,4-dihydroxystyrene, 2,4,6- Trihydroxystyrene, 4-t-butoxystyrene, 4-t Butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene, 4- (2-ethyl-2-propoxy) -α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- ( 1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, benzyl (meth) acrylate, acenaphthylene, 5-hydroxyacenaphthylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6 Vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate, 1-anthryl (meth) acrylate, 2-anthryl (meth) acrylate, 9-anthryl (meth) Acrylate, 9-anthrylmethyl (meth) acrylate, 1-vinyl A monomer having an aromatic skeleton such as lupine;

  Methylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2,5-dimethyl-2,5-hexanediol di ( (Meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,4-bis (2-hydroxypropyl) benzenedi (meth) acrylate, 1,3-bis List units in which a polymerizable unsaturated bond of a polyfunctional monomer such as a polyfunctional monomer having no bridged hydrocarbon skeleton such as (2-hydroxypropyl) benzenedi (meth) acrylate is cleaved Can do.

  Among these repeating units other than the above formulas (1) to (5), a unit in which a polymerizable unsaturated bond of (meth) acrylic acid ester having a bridged hydrocarbon skeleton is cleaved is preferable.

  In the resin (A), the content of the repeating unit (1) is usually 10 to 90 mol%, preferably 10 to 80 mol%, more preferably 20 to 70 mol%, based on all repeating units. In this case, if the content of the repeating unit (1) is less than 10 mol%, the resolution as a resist may be deteriorated, while if it exceeds 90 mol%, the developability of the resist may be deteriorated.

  Moreover, the content rate of a repeating unit (2) is 10-70 mol% normally with respect to all the repeating units, Preferably it is 15-65 mol%, More preferably, it is 20-60 mol%. In this case, when the content of the repeating unit (2) is less than 10 mol%, the resist has poor solubility in an alkaline developer, which may contribute to development defects or deteriorate the exposure margin. The exposure margin indicates a change in line width with respect to a change in exposure amount. On the other hand, when it exceeds 70 mol%, the solubility of the resist in the solvent is lowered, and the resolution may be lowered.

  Moreover, the content rate of another repeating unit (3) is 30 mol% or less normally with respect to all the repeating units, Preferably it is 25 mol% or less. In this case, if the content of the other repeating unit (3) exceeds 30 mol%, the resulting resist film may be easily swollen by the alkali developer or the solubility in the alkali developer may be reduced. . Furthermore, the content of the other repeating units (3) to (5) is usually 50 mol% or less, preferably 40 mol% or less, based on all repeating units.

  Moreover, the content rate of another repeating unit (4) is 30 mol% or less normally with respect to all the repeating units, Preferably it is 25 mol% or less. In this case, if the content of the other repeating unit (4) exceeds 30 mol%, the top loss of the resist pattern may occur and the pattern shape may be deteriorated.

  Moreover, the content rate of another repeating unit (5) is 30 mol% or less normally with respect to all the repeating units, Preferably it is 25 mol% or less. In this case, if the content of the other repeating unit (5) exceeds 30 mol%, the resulting resist film may be easily swollen by the alkali developer or the solubility in the alkali developer may be reduced. .

  In addition, the resin (A) in the present invention is, for example, a polymerizable unsaturated monomer corresponding to each predetermined repeating unit, radicals such as hydroperoxides, dialkyl peroxides, diacyl peroxides, and azo compounds. It can manufacture by superposing | polymerizing in a suitable solvent using a polymerization initiator in presence of a chain transfer agent as needed.

  Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cyclohexane, cycloheptane, cyclooctane, decalin, Cycloalkanes such as norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene; ethyl acetate Saturated carboxylic acid esters such as n-butyl acetate, i-butyl acetate and methyl propionate; ketones such as acetone, 2-butanone, 4-methyl-2-pentanone and 2-heptanone; tetrahydrofuran, dimethoxyethanes, Ethers such as diethoxyethanes It can be mentioned. These solvents can be used alone or in admixture of two or more.

  The reaction temperature in the polymerization is usually 40 to 150 ° C., preferably 50 to 120 ° C., and the reaction time is usually 1 to 48 hours, preferably 1 to 24 hours.

  Moreover, Mw by GPC method of resin (A) in this invention is although it does not specifically limit, Preferably it is 1,000-100,000, More preferably, it is 1,000-30,000, More preferably, it is 1,000-20. , 000. If the Mw of the resin (A) is less than 1,000, the heat resistance when used as a resist tends to decrease. On the other hand, if the Mw exceeds 100,000, the developability of the resist tends to decrease.

  Moreover, ratio (Mw / Mn) of Mw of resin (A) and Mn by GPC method is normally 1-5, Preferably it is 1-3.

  Moreover, in resin (A), content of the low molecular-weight component derived from the monomer used when preparing this resin (A) is 0.1 with respect to 100 mass% of this resin in conversion of solid content. It is preferably at most mass%, more preferably at most 0.07 mass%, still more preferably at most 0.05 mass%. When this content is 0.1% by mass or less, it is possible to reduce the amount of the eluate in the immersion exposure liquid such as water that is in contact with the immersion exposure. Furthermore, foreign matters are not generated in the resist during resist storage, and coating unevenness does not occur during resist application, and the occurrence of defects during resist pattern formation can be sufficiently suppressed.

  Examples of the low molecular weight component derived from the monomer include a monomer, a dimer, a trimer, and an oligomer, and can be a component having an Mw of 500 or less. The components having an Mw of 500 or less can be removed by, for example, chemical purification methods such as washing with water and liquid-liquid extraction, or a combination of these chemical purification methods and physical purification methods such as ultrafiltration and centrifugation. it can. Moreover, it can analyze by the high performance liquid chromatography (HPLC) of resin.

  In addition, resin (A) is so preferable that there is little content of impurities, such as a halogen and a metal, Thereby, the sensitivity at the time of setting it as a resist, resolution, process stability, a pattern shape, etc. can be improved further.

  Examples of the purification method of the resin (A) include chemical purification methods such as washing with water and liquid-liquid extraction, and combinations of these chemical purification methods with physical purification methods such as ultrafiltration and centrifugation, etc. Can be mentioned.

  Moreover, in this invention, resin (A) can be used individually or in mixture of 2 or more types.

<Radiation sensitive acid generator (B)>
The radiation-sensitive acid generator used in the present embodiment is composed of a radiation-sensitive acid generator that generates an acid upon exposure (hereinafter simply referred to as “acid generator (B)”). The acid generator (B) dissociates the acid dissociable group in the repeating unit present in the copolymer by the action of the acid generated by exposure (releases the protecting group), and as a result, the resist film is exposed. The portion becomes readily soluble in an alkali developer and has a function of forming a positive resist pattern. As an acid generator (B) in this embodiment, what contains the compound (henceforth "the acid generator 1") represented by following General formula (2) is preferable.

In the general formula (2), R ² is a hydrogen atom, a fluorine atom, a hydroxyl group, a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxyl group having 1 to 10 carbon atoms, A linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms is shown, and R ³ is a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxyl group, or a linear chain having 1 to 10 carbon atoms. Represents a branched or cyclic alkanesulfonyl group, and R ⁴ is independently a linear or branched alkyl group having 1 to 10 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group. Or two R ⁴ 's bonded to each other to form a divalent group having 2 to 10 carbon atoms, the divalent group may be substituted, and k is 0 to 2 is an integer, Y ^- have the ^{formula: R} 5 C F _2n SO ₃ ^- (wherein, ^{R 5} represents a fluorine atom or substituted optionally also good C1-12 hydrocarbon radical, n is an is an integer of 1 to 10) anion represented by, An anion represented by R ⁵ SO ₃ ^— or an anion represented by the following general formulas (3-1) and (3-2) is shown, and r is an integer of 0 to 8. )

(In General Formulas (3-1) and (3-2), R ⁶ independently represents an alkyl group containing a linear or branched fluorine atom having 1 to 10 carbon atoms, or two R 6 groups. ⁶ are bonded to each other to form a group containing a divalent fluorine atom having 2 to 10 carbon atoms, and the divalent group may be substituted.)

In the general formula (2), examples of the linear or branched alkyl group having 1 to 10 carbon atoms of R ² , R ³ and R ⁴ include a methyl group, an ethyl group, an n-propyl group, and i-propyl. Group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl Group, n-nonyl group, n-decyl group and the like. Of these alkyl groups, a methyl group, an ethyl group, an n-butyl group, a t-butyl group, and the like are preferable.

Examples of the linear or branched alkoxy group having 1 to 10 carbon atoms of ^{R 2} and ^{R 3,} for example, a methoxy group, an ethoxy group, n- propoxy group, i- propoxy, n- butoxy group, 2 -Methylpropoxy group, 1-methylpropoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group , N-nonyloxy group, n-decyloxy group and the like. Of these alkoxyl groups, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, and the like are preferable.

Examples of the linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms of R ² include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, and an n-butoxycarbonyl group. Group, 2-methylpropoxycarbonyl group, 1-methylpropoxycarbonyl group, t-butoxycarbonyl group, n-pentyloxycarbonyl group, neopentyloxycarbonyl group, n-hexyloxycarbonyl group, n-heptyloxycarbonyl group, n -An octyloxycarbonyl group, 2-ethylhexyloxycarbonyl group, n-nonyloxycarbonyl group, n-decyloxycarbonyl group, etc. can be mentioned. Of these alkoxycarbonyl groups, a methoxycarbonyl group, an ethoxycarbonyl group, an n-butoxycarbonyl group, and the like are preferable.

Examples of the linear, branched or cyclic alkanesulfonyl group having 1 to 10 carbon atoms of R ³ include a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, and a tert- Butanesulfonyl group, n-pentanesulfonyl group, neopentanesulfonyl group, n-hexanesulfonyl group, n-heptanesulfonyl group, n-octanesulfonyl group, 2-ethylhexanesulfonyl group, n-nonanesulfonyl group, n-decanesulfonyl Group, cyclopentanesulfonyl group, cyclohexanesulfonyl group and the like. Of these alkanesulfonyl groups, a methanesulfonyl group, an ethanesulfonyl group, an n-propanesulfonyl group, an n-butanesulfonyl group, a cyclopentanesulfonyl group, a cyclohexanesulfonyl group, and the like are preferable.

  Moreover, as r, 0-2 are preferable.

In the general formula (2), examples of the optionally substituted phenyl group represented by R ⁴ include a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,3-dimethylphenyl group, 2 , 4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,4,6-trimethylphenyl group, 4 -Substituted by phenyl groups such as ethylphenyl group, 4-t-butylphenyl group, 4-cyclohexylphenyl group, 4-fluorophenyl group, or linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms Phenyl group; these phenyl group or alkyl-substituted phenyl group can be substituted with hydroxyl group, carboxyl group, cyano group, nitro group, alkoxyl group, alkoxyalkyl group. And a group substituted with at least one group such as a group, an alkoxycarbonyl group, and an alkoxycarbonyloxy group.

  Among the substituents for the phenyl group and the alkyl-substituted phenyl group, examples of the alkoxyl group include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, 2-methylpropoxy group, 1- Examples thereof include straight-chain, branched or cyclic alkoxyl groups having 1 to 20 carbon atoms such as methylpropoxy group, t-butoxy group, cyclopentyloxy group and cyclohexyloxy group.

  Examples of the alkoxyalkyl group include those having 2 to 21 carbon atoms such as a methoxymethyl group, an ethoxymethyl group, a 1-methoxyethyl group, a 2-methoxyethyl group, a 1-ethoxyethyl group, and a 2-ethoxyethyl group. Examples thereof include linear, branched or cyclic alkoxyalkyl groups. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, an n-butoxycarbonyl group, a 2-methylpropoxycarbonyl group, and a 1-methylpropoxycarbonyl group. , T-butoxycarbonyl group, cyclopentyloxycarbonyl group, cyclohexyloxycarbonyl and the like, and linear, branched or cyclic alkoxycarbonyl groups having 2 to 21 carbon atoms.

Examples of the alkoxycarbonyloxy group include methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propoxycarbonyloxy group, i-propoxycarbonyloxy group, n-butoxycarbonyloxy group, t-butoxycarbonyloxy group, Examples thereof include linear, branched or cyclic alkoxycarbonyloxy groups having 2 to 21 carbon atoms such as cyclopentyloxycarbonyl group and cyclohexyloxycarbonyl. Examples of the optionally substituted phenyl group represented by R ⁴ in the general formula (2) include a phenyl group, a 4-cyclohexylphenyl group, a 4-t-butylphenyl group, a 4-methoxyphenyl group, and a 4-t-butoxyphenyl group. Etc. are preferred.

Examples of the optionally substituted naphthyl group for R ⁴ include 1-naphthyl group, 2-methyl-1-naphthyl group, 3-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 4-methyl-1-naphthyl group, 5-methyl-1-naphthyl group, 6-methyl-1-naphthyl group, 7-methyl-1-naphthyl group, 8-methyl-1-naphthyl group, 2,3-dimethyl -1-naphthyl group, 2,4-dimethyl-1-naphthyl group, 2,5-dimethyl-1-naphthyl group, 2,6-dimethyl-1-naphthyl group, 2,7-dimethyl-1-naphthyl group, 2,8-dimethyl-1-naphthyl group, 3,4-dimethyl-1-naphthyl group, 3,5-dimethyl-1-naphthyl group, 3,6-dimethyl-1-naphthyl group, 3,7-dimethyl- 1-naphthyl group, 3,8-dimethyl-1-naphth Til group, 4,5-dimethyl-1-naphthyl group, 5,8-dimethyl-1-naphthyl group, 4-ethyl-1-naphthyl group, 2-naphthyl group, 1-methyl-2-naphthyl group, 3- A naphthyl group substituted with a naphthyl group such as a methyl-2-naphthyl group or 4-methyl-2-naphthyl group or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms; these naphthyl groups or alkyls Examples include a group in which a substituted naphthyl group is substituted with at least one group such as a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkoxyl group, an alkoxyalkyl group, an alkoxycarbonyl group, and an alkoxycarbonyloxy group. Can do.

Examples of the alkoxyl group, alkoxyalkyl group, alkoxycarbonyl group, and alkoxycarbonyloxy group that are the substituents include the groups exemplified for the phenyl group and the alkyl-substituted phenyl group. As the naphthyl group which may be substituted for R ⁴ in the general formula (2), 1-naphthyl group, 1- (4-methoxynaphthyl) group, 1- (4-ethoxynaphthyl) group, 1- (4- n-propoxynaphthyl) group, 1- (4-n-butoxynaphthyl) group, 2- (7-methoxynaphthyl) group, 2- (7-ethoxynaphthyl) group, 2- (7-n-propoxynaphthyl) group , 2- (7-n-butoxynaphthyl) group and the like are preferable.

In addition, as the divalent group having 2 to 10 carbon atoms formed by bonding two R ⁴ to each other, a 5-membered or 6-membered ring, particularly preferably a 5-membered ring, together with the sulfur atom in the formula (2). Groups that form a ring (ie, a tetrahydrothiophene ring) are desirable. Examples of the substituent for the divalent group include the hydroxyl group, carboxyl group, cyano group, nitro group, alkoxyl group, alkoxyalkyl group, alkoxycarbonyl group exemplified as the substituent for the phenyl group and alkyl-substituted phenyl group. Group, alkoxycarbonyloxy group and the like. The R ⁴ in general formula (2), a methyl group, an ethyl group, a phenyl group, a 4-methoxyphenyl group, a 1-naphthyl group, form a tetrahydrothiophene ring structure together with two coupling R ⁴ each other to a sulfur atom A divalent group is preferred.

  Preferred cation sites of general formula (2) include triphenylsulfonium cation, tri-1-naphthylsulfonium cation, tri-tert-butylphenylsulfonium cation, 4-fluorophenyl-diphenylsulfonium cation, di-4-fluorophenyl- Phenylsulfonium cation, tri-4-fluorophenylsulfonium cation, 4-cyclohexylphenyl-diphenylsulfonium cation, 4-methanesulfonylphenyl-diphenylsulfonium cation, 4-cyclohexanesulfonyl-diphenylsulfonium cation, 1-naphthyldimethylsulfonium cation, 1- Naphthyldiethylsulfonium cation, 1- (4-hydroxynaphthyl) dimethylsulfonium cation, 1- (4- Tylnaphthyl) dimethylsulfonium cation, 1- (4-methylnaphthyl) diethylsulfonium cation, 1- (4-cyanonaphthyl) dimethylsulfonium cation, 1- (4-cyanonaphthyl) diethylsulfonium cation, 1- (3,5-dimethyl -4-hydroxyphenyl) tetrahydrothiophenium cation, 1- (4-methoxynaphthyl) tetrahydrothiophenium cation, 1- (4-ethoxynaphthyl) tetrahydrothiophenium cation, 1- (4-n-propoxynaphthyl) Tetrahydrothiophenium cation, 1- (4-n-butoxynaphthyl) tetrahydrothiophenium cation, 2- (7-methoxynaphthyl) tetrahydrothiophenium cation, 2- (7-ethoxynaphthyl) tetrahydride Thiophenium cation, 2- (7-n- propoxy-naphthyl) tetrahydrothiophenium cation, 2- (7-n- butoxynaphthyl) tetrahydrothiophenium cation, and the like.

The C _n F _2n — group in the R ⁵ C _n F _2n SO ₃ ^— anion represented by Y ⁻ in the general formula (2) is a perfluoroalkylene group having n carbon atoms, but the group is linear Or it can be branched. Here, n is preferably 1, 2, 4 or 8. The _optionally substituted hydrocarbon group having 1 to 12 carbon atoms in R ⁵ in R ⁵ C _n F _2n SO ₃ ^— and R ⁵ SO ₃ ^— anion includes an alkyl group having 1 to 12 carbon atoms and a cycloalkyl group. And a bridged alicyclic hydrocarbon group are preferred. Specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, neopentyl group N-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, norbornyl group, norbornylmethyl group, hydroxynorbornyl group, adamantyl group Etc.

In general formulas (3-1) and (3-2), R ⁶ independently represents an alkyl group containing a linear or branched fluorine atom having 1 to 10 carbon atoms, such as a trifluoromethyl group or a pentafluoroethyl group. , Heptafluoropropyl group, nonafluorobutyl group, dodecafluoropentyl group, perfluorooctyl group and the like.

Examples of the group containing two R ⁶ bonded to each other and containing a divalent fluorine atom having 2 to 10 carbon atoms include a tetrafluoroethylene group, a hexafluoropropylene group, an octafluorobutylene group, a decafluoropentylene group, A decafluorohexylene group etc. can be mentioned.

  Preferred anion sites of the general formulas (3-1) and (3-2) include trifluoromethanesulfonate anion, perfluoro-n-butanesulfonate anion, perfluoro-n-octanesulfonate anion, 2-bicyclo [2.2 .1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate anion, 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate anion, 1-adamantyl Examples include sulfonate anions and anions exemplified by the following formulas (3-1-1) to (3-1-7).

  The acid generator (B) is given by the combination of the cation and the anion exemplified above, but the combination is not particularly limited. In the present invention, the acid generator (B) may be used alone or in combination. It can also be used by mixing more than one species.

  Moreover, as a radiation sensitive acid generator (henceforth "other acid generator") other than the said acid generator (B) which can be used as a radiation sensitive acid generator in this invention, it is, for example. Onium salt compounds, halogen-containing compounds, diazoketone compounds, sulfone compounds, sulfonic acid compounds, and the like. Examples of these other acid generators include the following.

Onium salt compounds:
Examples of the onium salt compound include iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Specific examples of the onium salt compound include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hepta-2. -Yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis ( 4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2- Te La tetrafluoroethane sulfonate, cyclohexyl 2-oxo-cyclohexyl methyl trifluoromethanesulfonate, dicyclohexyl-2-oxo-cyclohexyl trifluoromethane sulfonate, and 2-oxo-cyclohexyl dimethyl sulfonium trifluoromethanesulfonate, and the like.

Halogen-containing compounds:
Examples of the halogen-containing compound include a haloalkyl group-containing hydrocarbon compound and a haloalkyl group-containing heterocyclic compound.

  Specific examples of halogen-containing compounds include (trichloromethyl such as phenylbis (trichloromethyl) -s-triazine, 4-methoxyphenylbis (trichloromethyl) -s-triazine, 1-naphthylbis (trichloromethyl) -s-triazine. ) -S-triazine derivatives and 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane.

Diazo ketone compounds:
Examples of the diazo ketone compound include a 1,3-diketo-2-diazo compound, a diazobenzoquinone compound, a diazonaphthoquinone compound, and the like.

  Specific examples of the diazo ketone include 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonyl chloride, 1,2, naphthoquinonediazide of 2,3,4,4′-tetrahydroxybenzophenone. -4-sulfonic acid ester or 1,2-naphthoquinonediazide-5-sulfonic acid ester, 1,1,1-naphthoquinonediazide-4-sulfonic acid ester of 1,1,1-tris (4-hydroxyphenyl) ethane Examples include 2-naphthoquinonediazide-5-sulfonic acid ester.

Sulfone compounds:
Examples of the sulfone compound include β-ketosulfone, β-sulfonylsulfone, and α-diazo compounds of these compounds.

  Specific examples of the sulfone compound include 4-trisphenacylsulfone, mesitylphenacylsulfone, bis (phenylsulfonyl) methane, and the like.

Sulfonic acid compounds:
Examples of the sulfonic acid compounds include alkyl sulfonic acid esters, alkyl sulfonic acid imides, haloalkyl sulfonic acid esters, aryl sulfonic acid esters, and imino sulfonates.

  Specific examples of the sulfonic acid compound include benzoin tosylate, pyrogallol tris (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2.2.1] hept-5. -Ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2.2. 1] Hept-5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonylbicyclo [2.2.1] ] Hept-5-ene-2,3-dicarbodiimide, N- (trifluoromethanesulfonylo Succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide, N- (perfluoro-n-octanesulfonyloxy) succinimide, N- (2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonyloxy) succinimide, 1,8-naphthalenedicarboxylic imide trifluoromethanesulfonate, 1,8-naphthalenedicarboxylic imidononafluoro-n-butanesulfonate, 1,8-naphthalenedicarboxylic Examples include acid imido perfluoro-n-octane sulfonate.

  Among these other acid generators, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hepta- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-Butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2 -Tetraph Oro ethanesulfonate, cyclohexyl 2-oxo-cyclohexyl methyl trifluoromethanesulfonate, dicyclohexyl-2-oxo-cyclohexyl trifluoromethane sulfonate, 2-oxo-cyclohexyl dimethyl sulfonium trifluoromethane sulfonate,

  Trifluoromethanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide Perfluoro-n-octanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, N- (trifluoromethanesulfonyloxy) succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide N- (perfluoro-n-octanesulfonyloxy) succinimide, N- (2-bicyclo [2.2 1] hept-2-yl-1,1,2,2-tetrafluoroethane sulfonyloxy) succinimide, 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate and the like are preferable. The other acid generators can be used alone or in admixture of two or more.

  In the present invention, the total amount of the acid generator (B) and the other acid generator used ensures the sensitivity and developability as a resist, and the resist film comes into contact with an immersion liquid (in this case, water). From the viewpoint of suppressing elution of the content occurring in the resin, it is usually 0.1 to 3 parts by mass, preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the resin. In this case, if the total amount used is less than 0.1 parts by mass, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 3 parts by mass, the resist film comes into contact with the immersion liquid (in this case, water). There is a tendency that elution of the contents occurring at the time cannot be suppressed. Moreover, the usage-amount of another acid generator is 80 mass% or less normally with respect to the sum total of an acid generator (B) and another acid generator, Preferably it is 60 mass% or less.

<Low molecular compound (C) that becomes alkali-soluble by the action of acid>
The radiation sensitive resin composition of the present invention is low in alkali solubility due to the action of an acid represented by the following general formula (1) for the purpose of reducing roughness generated by a low addition amount of the acid generator (B). The molecular compound (C) (hereinafter simply referred to as “low molecular compound (C)”) is contained.

(In the general formula (1), R ¹ independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ¹ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ^{1 's} are bonded to each other, together with the carbon atom to which each is bonded, 20 divalent alicyclic hydrocarbon groups or derivatives thereof, and the remaining R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent fat having 4 to 20 carbon atoms A cyclic hydrocarbon group or a derivative thereof, X is independently of each other hydrogen or a hydroxy group, at least one is a hydroxy group, A is a single bond or a group represented by -D-COO-, D is a methylene group having 2 to 4 carbon atoms Represents an alkylene group.)

  In the general formula (1), A represents a single bond or a divalent linking group. Examples of the divalent linking group include a methylene group, a methylenecarbonyl group, a methylenecarbonyloxy group, an ethylene group, an ethylenecarbonyl group, and an ethylenecarbonyl group. An oxy group, a propylene group, a propylene carbonyl group, a propylene carbonyloxy group, etc. are mentioned. Particularly preferred is a methylenecarbonyloxy group.

In the general formula (1), a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms of R ^{1 and} a divalent hydrocarbon group having 4 to 20 carbon atoms formed by bonding any two R ¹ to each other. Examples of the alicyclic hydrocarbon group include alicyclic rings derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cycloalkanes such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. A group consisting of these alicyclic rings is, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t -The group etc. which substituted by 1 or more types or 1 or more of C1-C4 linear, branched or cyclic alkyl groups, such as a butyl group, can be mentioned. Among these alicyclic hydrocarbon groups, a group consisting of an alicyclic ring derived from norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclopentane or cyclohexane, or a group consisting of these alicyclic rings is described above. A group substituted with an alkyl group is preferred.

  Examples of the alicyclic hydrocarbon group derivative include hydroxyl group; carboxyl group; oxo group (that is, ═O group); hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1- Hydroxypropyl groups having 1 to 4 carbon atoms such as hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkoxyl group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, a 2-methylpropoxy group, a 1-methylpropoxy group and a t-butoxy group; Group: C2-C5 such as cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, etc. A substituent such as Anoarukiru group can include one or more or one or more having groups. Of these substituents, a hydroxyl group, a carboxyl group, a hydroxymethyl group, a cyano group, a cyanomethyl group, and the like are preferable.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms of R ¹ include, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methylpropyl. Group, 1-methylpropyl group, t-butyl group and the like. Of these alkyl groups, a methyl group, an ethyl group, an n-propyl group, and an i-propyl group are preferable.

  Preferred low molecular compounds (C) include the following formulas (9-1) to (9-12).

  In this invention, the addition amount of a low molecular compound (C) is 0.1-20 mass parts normally with respect to 100 mass parts of resin, Preferably it is 1-10 mass parts. In this case, if the total amount used is less than 0.1 parts by mass, the effect of improving LER and LWR tends not to be seen, whereas if it exceeds 20 parts by mass, the resolution and exposure margin of the resist tend to decrease. is there.

<Solvent (D)>
The radiation-sensitive resin composition of the present invention is usually dissolved in a solvent so that the total solid content concentration is usually 1 to 50% by mass, preferably 1 to 25% by mass. A composition solution is prepared by filtering with a filter having a pore size of about 0.2 μm.

  Examples of the solvent (D) include 2-butanone, 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 4-methyl-2-pentanone, 3-methyl-2-pentanone, 3,3- Linear or branched ketones such as dimethyl-2-butanone, 2-heptanone, 2-octanone; cyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 2,6-dimethylcyclohexanone, Cyclic ketones such as isophorone; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-i-propyl ether acetate, propylene glycol mono-n-butyl Propylene glycol monoalkyl ether acetates such as ether acetate, propylene glycol mono-i-butyl ether acetate, propylene glycol mono-sec-butyl ether acetate, propylene glycol mono-t-butyl ether acetate; methyl 2-hydroxypropionate, 2-hydroxypropionic acid Ethyl, 2-hydroxypropionate n-propyl, 2-hydroxypropionate i-propyl, 2-hydroxypropionate n-butyl, 2-hydroxypropionate i-butyl, 2-hydroxypropionate sec-butyl, 2-hydroxy Alkyl 2-hydroxypropionates such as t-butyl propionate; methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 3-ethoxy Methyl propionate, other 3-alkoxy propionic acid alkyl such as ethyl 3-ethoxypropionate,

  n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclohexanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether , Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, propylene glycol monomethyl ether , Propylene glycol monoethyl Ether, propylene glycol mono-n-propyl ether, toluene, xylene, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate, Ethyl acetoacetate, methyl pyruvate, ethyl pyruvate, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, benzyl ethyl ether, di-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol Cole monoethyl ether, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, etc. Can do.

Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, alkyl 2-hydroxypropionate, alkyl 3-alkoxypropionate, γ-butyrolactone and the like are preferable. .
These solvent (D) can be used individually or in mixture of 2 or more types.

<Other additives>
Various additives such as nitrogen-containing compounds, other alicyclic additives, surfactants, and sensitizers can be blended with the radiation-sensitive resin composition of the present invention, if necessary.

<Nitrogen-containing compound>
The nitrogen-containing compound used in the present invention acts as an acid diffusion control agent that controls the diffusion phenomenon in the resist film of the acid generated from the acid generator upon exposure and suppresses undesired chemical reactions in non-exposed areas. By blending such an acid diffusion controller, the storage stability of the resulting radiation-sensitive resin composition is improved, the resolution as a resist is further improved, and the process from exposure to heat treatment after exposure is improved. A change in the line width of the resist pattern due to fluctuations in the placement time (PED) can be suppressed, and a composition having extremely excellent process stability can be obtained.

  Examples of the acid diffusion controller include “tertiary amine compound”, “amide group-containing compound”, “quaternary ammonium hydroxide compound”, “other nitrogen-containing heterocyclic compound” and the like.

  Examples of the “tertiary amine compound” include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n. -Tri (cyclo) alkylamines such as octylamine, cyclohexyldimethylamine, dicyclohexylmethylamine, tricyclohexylamine; aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4 -Aromatic amines such as methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline; alkanolamines such as triethanolamine, N, N-di (hydroxyethyl) aniline; N , N, N ′, N′-Tetramethylethyl Diamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzenetetramethylenediamine, bis (2- Examples thereof include dimethylaminoethyl) ether and bis (2-diethylaminoethyl) ether.

  Examples of the “amide group-containing compound” include Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt -Butoxycarbonyldicyclohexylamine, Nt-butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, (S)- (-)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxy Piperidine, Nt-butoxycarbonylpyrrolidine, Nt-butoxycarbonyl Perazine, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-butoxycarbonyl-4,4′- Diaminodiphenylmethane, N, N′-di-t-butoxycarbonylhexamethylenediamine, N, N, N′N′-tetra-t-butoxycarbonylhexamethylenediamine, N, N′-di-t-butoxycarbonyl-1 , 7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxycarbonyl-1,9-diaminononane, N, N′-di- t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N -Di-t-butoxycarbonyl-4,4'-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole Nt-butoxycarbonyl group-containing amino compounds such as

  Examples of the “quaternary ammonium hydroxide compound” include tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.

  Examples of the “other nitrogen-containing heterocyclic compound” include pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, 2-methyl- Pyridines such as 4-phenylpyridine, nicotine, nicotinic acid, nicotinamide, quinoline, 4-hydroxyquinoline, 8-oxyquinoline and acridine; in addition to piperazines such as piperazine and 1- (2-hydroxyethyl) piperazine, Pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 3-piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2 ] Octane, imidazole, 4-methylimi Dazole, 1-benzyl-2-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole Nt-butoxycarbonyl-2-phenylbenzimidazole and the like.

  The nitrogen-containing compounds can be used alone or in admixture of two or more.

  In the present invention, the total amount of the nitrogen-containing compound used is usually less than 10 parts by mass, preferably less than 5 parts by mass with respect to 100 parts by mass of the resin, from the viewpoint of ensuring high sensitivity as a resist. In this case, when the total usage exceeds 10 parts by mass, the sensitivity as a resist tends to be remarkably lowered. In addition, if the usage-amount of a nitrogen-containing compound is less than 0.001 mass part, there exists a possibility that the pattern shape and dimension fidelity as a resist may fall depending on process conditions.

Examples of the alicyclic additive other than the low molecular compound (C) include 1-adamantanecarboxylic acid, 2-adamantanone, 1-adamantanecarboxylate t-butyl, 1-adamantanecarboxylate t-butoxycarbonylmethyl, 1 -Adamantanecarboxylic acid α-butyrolactone ester, 1,3-adamantane dicarboxylic acid di-t-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantane diacetate di-t Adamantane derivatives such as butyl, 2,5-dimethyl-2,5-di (adamantylcarbonyloxy) hexane; dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-butyl adipate, di-t-adipate Alkyl carboxylic acid esters such as butyl, 3- [ - hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^{2, 5.} 1 ^7,10 ] dodecane and the like. These alicyclic additives can be used alone or in admixture of two or more.

  The surfactant is a component having an action of improving coating properties, striation, developability and the like.

  Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, and polyethylene glycol dilaurate. In addition to nonionic surfactants such as polyethylene glycol distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (manufactured by Tochem Products), Megafax F171, F173 (manufactured by Dainippon Ink and Chemicals), Florard FC430, FC431 (Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (made by Asahi Glass Co., Ltd.), etc. Can do. These surfactants can be used alone or in admixture of two or more.

  The sensitizer absorbs radiation energy and transmits the energy to the acid generator (B), thereby increasing the amount of acid produced. The radiation-sensitive resin composition It has the effect of improving the apparent sensitivity.

  Examples of such sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. These sensitizers can be used alone or in admixture of two or more.

  In addition, by blending a dye or pigment, the latent image of the exposed area can be visualized, and the influence of halation during exposure can be alleviated, and by blending an adhesion aid, adhesion to the substrate can be improved. it can.

  Furthermore, examples of additives other than the above include alkali-soluble resins, low-molecular alkali-solubility control agents having acid-dissociable protecting groups, antihalation agents, storage stabilizers, antifoaming agents, and the like.

<Method for forming resist pattern>
The radiation sensitive resin composition of the present invention is particularly useful as a chemically amplified resist. In the chemically amplified resist, the acid-dissociable group in the resin component [mainly resin (B)] is dissociated by the action of the acid generated from the acid generator by exposure to generate a carboxyl group, and as a result, The solubility of the exposed portion of the resist in the alkaline developer is increased, and the exposed portion is dissolved and removed by the alkaline developer to obtain a positive resist pattern.

  When forming a resist pattern from the radiation-sensitive resin composition of the present invention, the resin composition solution is coated with, for example, a silicon wafer or aluminum by an appropriate application means such as spin coating, cast coating, or roll coating. A resist film is formed by coating on a substrate such as a wafer, and this resist is formed so that a predetermined resist pattern is formed after a heat treatment (hereinafter referred to as “PB”) in some cases. Expose the coating. The radiation used at this time is appropriately selected from visible rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams, etc., depending on the type of acid generator used. ArF excimer laser Far ultraviolet rays represented by (wavelength 193 nm) or KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser (wavelength 193 nm) is particularly preferable.

  Moreover, exposure conditions, such as exposure amount, are suitably selected according to the compounding composition of a radiation sensitive resin composition, the kind of additive, etc. In the present invention, it is preferable to perform heat treatment (PEB) after exposure. By PEB, the dissociation reaction of the acid dissociable group in the resin component proceeds smoothly. The heating condition of PEB varies depending on the composition of the radiation sensitive resin composition, but is usually 30 to 200 ° C, preferably 50 to 170 ° C.

  In the present invention, in order to maximize the potential of the radiation-sensitive resin composition, for example, as disclosed in Japanese Patent Publication No. 6-12252 (Japanese Patent Laid-Open No. 59-93448), etc. An organic or inorganic antireflection film may be formed on the substrate to be formed. Further, in order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film can be provided on the resist film as disclosed in, for example, JP-A-5-188598. Further, in order to prevent the acid generator and the like from flowing out of the resist film in immersion exposure, a liquid immersion protective film is provided on the resist film as disclosed in, for example, JP-A-2005-352384. You can also. These techniques can be used in combination.

  Next, the exposed resist film is developed to form a predetermined resist pattern. Examples of the developer used for this development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, and di-n-propyl. Amine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo -An alkaline aqueous solution in which at least one of alkaline compounds such as [4.3.0] -5-nonene is dissolved is preferable. The concentration of the alkaline aqueous solution is usually 10% by mass or less. In this case, if the concentration of the alkaline aqueous solution exceeds 10% by mass, the unexposed area may be dissolved in the developer, which is not preferable.

  In addition, for example, an organic solvent can be added to the developer composed of the alkaline aqueous solution. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclopentanone, cyclohexanone, 3-methylcyclopentanone, and 2,6-dimethylcyclohexanone; methyl alcohol, ethyl alcohol, and n-propyl. Alcohols such as alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclopentanol, cyclohexanol, 1,4-hexanediol, 1,4-hexanedimethylol; ethers such as tetrahydrofuran and dioxane Esters such as ethyl acetate, n-butyl acetate and i-amyl acetate; aromatic hydrocarbons such as toluene and xylene; phenol, acetonylacetone and dimethylformamide. These organic solvents can be used alone or in admixture of two or more. The amount of the organic solvent used is preferably 100% by volume or less with respect to the alkaline aqueous solution. In this case, if the amount of the organic solvent used exceeds 100% by volume, the developability is lowered, and there is a possibility that the remaining development in the exposed area increases. An appropriate amount of a surfactant or the like can be added to the developer composed of the alkaline aqueous solution.

  In addition, after developing with the developing solution which consists of alkaline aqueous solution, generally it wash | cleans with water and dries.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Here, the part is based on mass unless otherwise specified.

  Each measurement and evaluation in each of the following synthesis examples was performed in the following manner.

(1) Mw and Mn
Gel permeation chromatography using monodisperse polystyrene as standard using GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation under flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. (GPC). The degree of dispersion Mw / Mn was calculated from the measurement results.

^{(2) 13} C-NMR analysis of ¹³ C-NMR analysis the polymer, using a JEOL Ltd. "JNM-EX270", was measured.

(3) Amount of low molecular weight component derived from monomer Using an Intersil ODS-25 μm column (4.6 mmφ × 250 mm) manufactured by GL Sciences, a flow rate of 1.0 ml / min, elution solvent acrylonitrile / 0.1% phosphoric acid It measured by the high performance liquid chromatography (HPLC) on the analysis conditions of aqueous solution.

  Hereinafter, each synthesis example will be described.

  Each monomer used for the synthesis of each fluorine-containing polymer (A) and resin (B) is shown below as formulas (M-1) to (M-8).

<Synthesis of Resin (A-1)>
The following compound (M-1) 38.74 g (40 mol%) and compound (M-2) 61.26 g (60 mol%) were dissolved in 200 g of 2-butanone, and 2,2′-azobis (isobutyro) (Nitrile) A monomer solution charged with 3.85 g was prepared.

On the other hand, a 1000 ml three-necked flask charged with 100 g of 2-butanone was prepared and purged with nitrogen for 30 minutes. After the nitrogen purge, the contents in the three-necked flask were heated to 80 ° C. while stirring, and the monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or lower, poured into 2000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice as a slurry with 400 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder polymer (67 g, yield 67%). . This polymer has Mw of 4600, Mw / Mn of 1.66, and as a result of ¹³ C-NMR analysis, the content of each repeating unit derived from compound (M-1) and compound (M-2) is 43.2. : 56.8 (mol%) copolymer. This polymer is referred to as “resin (A-1)”. In addition, content of the low molecular weight component derived from each monomer in resin (A-1) was 0.05 mass% with respect to 100 mass% of this polymer.

<Preparation of radiation-sensitive resin composition>
Resin (A), acid generator (B), low molecular weight compound (C), solvent (D) and nitrogen-containing compound (E) were mixed in the proportions shown in Table 1, and Example 1 and Comparative Examples 1 and 2 were mixed. A radiation sensitive resin composition was prepared.

  Details of the acid generator (B), the low molecular compound (C), the solvent (D) and the nitrogen-containing compound (E) shown in Table 1 are shown below. In the table, “part” is based on mass unless otherwise specified.

<Acid generator (B)>
(B-1): Triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate (B-2): 4-cyclohexylphenyldiphenylsulfonium nona Fluoro-n-butanesulfonate

<Low molecular compound (C)>
(C-1): Compound 9-5

<Solvent (D)>
(D-1): Propylene glycol monomethyl ether acetate (D-2): Cyclohexanone (D-3): Gamma-butyrolactone <Nitrogen-containing compound (E)>
(E-1): 3-Piperidino-1,2-propanediol

<Evaluation of radiation-sensitive resin composition>
Various evaluation was performed as follows about each radiation sensitive resin composition of Example 1 and Comparative Examples 1 and 2. FIG. Table 2 shows the evaluation results regarding exposure conditions, sensitivity, elution, and roughness, and other evaluation results.

  Each evaluation method is as follows.

(1) Sensitivity A 12-inch silicon wafer having a 77 nm-thick lower layer antireflection film (“ARC29A”, manufactured by Brewer Science Co., Ltd.) formed on the surface was used as the substrate. For the formation of this antireflection film, “CLEAN TRACK ACT8” (manufactured by Tokyo Electron Ltd.) was used.

  Next, the radiation sensitive resin composition shown in Table 1 is spin-coated on the substrate by the CLEAN TRACK ACT8, and baking (PB) is performed under the conditions shown in Table 2 to form a resist film having a film thickness of 205 nm. did. This resist film was exposed through a mask pattern by an ArF excimer laser exposure apparatus (“NSR S306C”, manufactured by Nikon Corporation, irradiation conditions: NA 0.78 sigma 0.93 / 0.69). Then, after performing PEB under the conditions shown in Table 2, it was developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 30 seconds, washed with water, and dried to form a positive resist pattern. did. At this time, an exposure amount for forming a line-and-space pattern (1L1S) having a line width of 90 nm in a one-to-one line width was defined as an optimum exposure amount, and this optimum exposure amount was defined as sensitivity. For this measurement, a scanning electron microscope (“S-9380”, manufactured by Hitachi High-Technologies Corporation) was used.

(2) Measurement of Elution Amount As shown in FIG. 1, an 8-inch silicon wafer 3 that has been subjected to HMDS (hexamethyldisilazane) 31 treatment (100 ° C., 60 seconds) in advance using CLEAN TRACK ACT8 (manufactured by Tokyo Electron). A silicon rubber sheet 4 (manufactured by Kureha Elastomer Co., Ltd., thickness: 1.0 mm, shape: square with a side of 30 cm) was placed on the upper central portion. Next, 10 ml of ultrapure water 5 was filled in the hollowed-out portion at the center of the silicon rubber using a 10 mL hole pipette.

  Thereafter, a 77 nm-thick lower layer antireflection film (“ARC29A”, manufactured by Brewer Science) 61 is formed in advance by CLEAN TRACK ACT8, and then the radiation-sensitive resin composition shown in Table 1 is used in the CLEAN TRACK ACT8. The silicon wafer 6 on which the resist film 62 having a film thickness of 205 nm is formed by spin coating on the lower antireflection film 61 and baking (115 ° C., 60 seconds) is used. They were put on the silicon rubber sheet 4 so as to be in contact with each other and so that the ultrapure water 5 did not leak from the silicon rubber 4.

  And it kept for 10 seconds with the state. Thereafter, the 8-inch silicon wafer 6 was removed, and ultrapure water 5 was collected with a glass syringe, which was used as a sample for analysis. The recovery rate of ultrapure water after the experiment was 95% or more.

  Subsequently, the peak intensity of the anion part of the photoacid generator in the ultrapure water obtained above was calculated by LC-MS (liquid chromatograph mass spectrometer, LC part: SERIES1100 manufactured by AGILENT, MS part: Perseptive Biosystems, Inc. (Manufactured by Mariner) was measured under the following measurement conditions. At that time, each of the peak intensities of the 1 ppb, 10 ppb, and 100 ppb aqueous solutions of the photoacid generator was measured under the measurement conditions to prepare a calibration curve, and the elution amount was calculated from the peak intensity using the calibration curve. Similarly, each peak intensity of the 1 ppb, 10 ppb, and 100 ppb aqueous solutions of the acid diffusion control agent is measured under the measurement conditions to prepare a calibration curve, and the calibration curve is used to calculate the acid diffusion control agent from the peak intensity. The amount of elution was calculated.

When the elution amount was more than 5.0 × 10 ⁻¹² mol / cm ^2, it was ^judged as “bad”, and when it was below, it was judged as “good”.

(Column condition)
Column used: “CAPCELL PAK MG”, manufactured by Shiseido Co., Ltd., 1 flow rate: 0.2 ml / min Outflow solvent: 0.1% by mass of formic acid added to water / methanol (3/7) Measurement temperature: 35 ° C.

(3) Roughness measurement Using a scanning electron microscope ("S-9380", manufactured by Hitachi High-Technologies Corporation) with a 90 nm line and space pattern, 20-point length measurement was performed, the variation was calculated, and 3 sigma The value was roughness. This value was judged to be unsatisfactory at 10 nm or more and good at 10 nm or less.

  As apparent from Table 2, as a result of adding an acid generator of 3% by mass or less and adding a low molecular compound (C) that becomes alkali-soluble as in the present invention, no upper layer film is used in immersion exposure. However, the elution amount of the contents can be suppressed, and a radiation-sensitive resin composition having good LER and LWR can be provided, which is considered to work suitably in lithography that will be miniaturized in the future.

  INDUSTRIAL APPLICABILITY The present invention can be used as an immersion exposure resist used in immersion exposure in which a resist film is exposed through an immersion exposure liquid such as water.

It is a schematic diagram explaining the method of producing the sample for a measurement of the elution amount.

Explanation of symbols

  3: silicon wafer, 31: HMDS, 4: silicon rubber sheet, 5: ultrapure water, 6: silicon wafer, 61: antireflection film, 62: resist film

Claims (4)

A resin (A) that becomes alkali-soluble by the action of an acid, a radiation-sensitive acid generator (B), a low-molecular compound (C) that becomes alkali-soluble by the action of an acid, and a solvent (D). A radiation-sensitive resin composition for immersion exposure, wherein (C) is represented by the following general formula (1).

(In the general formula (1), R ¹ independently represents a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched alkyl group having 1 to 4 carbon atoms. And at least one of R ¹ is the alicyclic hydrocarbon group or a derivative thereof, or any two R ^{1 's} are bonded to each other, together with the carbon atom to which each is bonded, 20 divalent alicyclic hydrocarbon groups or derivatives thereof, and the remaining R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent fat having 4 to 20 carbon atoms A cyclic hydrocarbon group or a derivative thereof, X is independently of each other hydrogen or a hydroxy group, at least one is a hydroxy group, A is a single bond or a group represented by -D-COO-, D is a methylene group having 2 to 4 carbon atoms Represents an alkylene group.) The radiation sensitive acid generator (B) has a structure represented by the following general formula (2), and the total content is 0.1 to 3.0 when the resin (A) is 100 parts by mass. The radiation-sensitive resin composition for immersion exposure according to claim 1, wherein the composition is part by mass.

(In General Formula (2), R ² is a hydrogen atom, a fluorine atom, a hydroxyl group, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkoxyl group having 1 to 10 carbon atoms. Represents a linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms, and R ³ represents a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxyl group, or a linear chain having 1 to 10 carbon atoms. , R ⁴ is independently a linear or branched alkyl group having 1 to 10 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group. Or two R ^{4 s} are bonded to each other to form a divalent group having 2 to 10 carbon atoms, the divalent group may be substituted, and Y ⁻ represents R _{^{5 C n F 2n SO 3 -}} , R SO ₃ ^- (. Wherein, ^{R 5} is a fluorine atom, or a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, n is an integer of 1 to 10), or And an anion represented by the following general formula (3-1) or (3-2), r is an integer of 0 to 8, and k is an integer of 0 to 2.)

(In each formula, R ⁶ is independently of each other a fluorine atom and a linear or branched alkyl group having 1 to 10 carbon atoms, or two R ⁶ are bonded to each other, (It is a divalent organic group having 2 to 10 carbon atoms and having a fluorine atom, and the divalent organic group may have a substituent.)   The radiation sensitive resin composition for immersion exposure according to claim 1 or 2, wherein the resin (A) contains a repeating unit containing a lactone structure. In a resist pattern forming method including immersion exposure in which radiation is irradiated between a lens and a photoresist film through an immersion exposure liquid having a refractive index at a wavelength of 193 nm higher than that of air,
A resist in which the photoresist film is formed using the radiation-sensitive resin composition for immersion exposure according to claims 1 to 3, and the formed photoresist film and the immersion exposure liquid are in direct contact with each other. Pattern formation method.

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