Resin, water repellency improver, and liquid immersion upper layer film-forming composition

Abstract

Provided are a resin, a water repellency improver, and an immersion upper layer film-forming composition, which can easily impart, improve, or enhance the water repellency of a resist film or the like. The present invention provides a resin having a first structural unit represented by the following formula (2): JPEG2026035870000041.jpg57159 In formula (2), X is a divalent linking group. R is a hydrogen atom, a fluorine atom, or a monovalent hydrocarbon group that is unsubstituted or substituted with a halogen atom or an alkoxy group. R 3 is a fluorinated chain hydrocarbon group having 1 to 4 carbon atoms.

Description

[Technical Field]

[0001] The present invention relates to a resin, a water repellency improver, and an immersion upper layer film-forming composition. [Background technology]

[0002]

[0003] As the structures of various electronic devices, such as semiconductor devices and liquid crystal devices, become finer, further miniaturization of resist patterns in lithography processes is required, and therefore, various radiation-sensitive resin compositions have been investigated. When such radiation-sensitive resin compositions are irradiated with radiation, such as far ultraviolet light from an ArF excimer laser or an electron beam, an acid is generated in the exposed area, and the catalytic action of this acid causes a difference in the dissolution rate in a developer between the exposed area and the unexposed area, thereby forming a resist pattern on a substrate.

[0003] For such radiation-sensitive resin compositions, liquid immersion lithography is used as a method for forming even finer resist patterns, for example, with line widths of about 45 nm. This method involves filling the exposure optical path space (between the lens and the resist film) with an immersion medium, such as pure water or a fluorine-based inert liquid, that has a refractive index (n) higher than that of air or an inert gas. Therefore, even if the numerical aperture (NA) of the lens is increased, the depth of focus is less likely to decrease, and high resolution can be achieved.

[0004] Resin compositions used in immersion lithography contain water-repellent polymer additives made of fluorine-containing polymers to enhance the hydrophobicity of the resist film surface. This suppresses the elution of photoacid generators and other additives from the resist film into the immersion medium, preventing degradation of resist film performance and contamination of equipment such as lenses, while also improving water drainage on the resist film surface to prevent watermarks and enable high-speed scanning (see, for example, Patent Document 1). However, increasing the hydrophobicity of the resist film surface reduces the surface wettability with developers and rinse solutions, which can lead to insufficient removal of development residues deposited on unexposed areas of the resist film surface during development, resulting in the occurrence of defects such as blob defects in the resist pattern. To prevent the occurrence of such defects, fluorine-containing polymers have been proposed that are hydrophobic during immersion lithography but hydrophilic during alkaline development (see, for example, Patent Document 2). The use of such polymers as water-repellent polymer additives is believed to be effective in suppressing defects. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2007 / 116664 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-32994 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the current trend toward finer resist patterns down to line widths of 45 nm or less, the level of defect suppression required is becoming even higher. Furthermore, the water-repellent polymer additive is also required to enhance the sensitivity of radiation-sensitive resin compositions containing the additive, thereby enabling high-precision patterns to be obtained with a high yield. However, the conventional radiation-sensitive resin compositions described above have not been able to satisfy these requirements.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition that has good sensitivity and is capable of forming a resist pattern that has high water repellency and few defects, a method for forming a resist pattern using the same, and a water repellency improver. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0009] That is, in one embodiment, the present invention provides: Resin A having a first structural unit including a partial structure represented by the following formula (1): [ka] (In formula (1), X is a divalent linking group. R 1 and R 2 are each independently a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, a monovalent fluorinated hydrocarbon group having 1 to 40 carbon atoms, or R 1 and R 2 are combined with each other together with the carbon atoms to which they are bonded to form a ring structure (a) having 3 to 20 ring members. R 3 is a fluorinated chain hydrocarbon group having 1 to 4 carbon atoms. * indicates the linking site with the polymer main chain.) Resin B containing a structural unit having an acid-dissociable group; a radiation-sensitive acid generator, and solvent The present invention relates to a radiation-sensitive resin composition comprising:

[0010] The radiation-sensitive resin composition of the present invention has good sensitivity and is capable of forming a resist pattern with high water repellency and few defects because it contains the above-mentioned resin A. The above-mentioned resin A is mainly composed of —C(═O)OCR 1 R 2 R 3 It is presumed that the excellent water repellency and water stability of the moiety contributes to the high water repellency of the resist pattern and the suppression of defects. However, the scope of the present invention is not necessarily limited by this presumption of the mechanism of action.

[0011] In the present invention, examples of the organic group include a monovalent hydrocarbon group, a group containing a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group, and a group in which some or all of the hydrogen atoms contained in the hydrocarbon group or the group containing a divalent heteroatom-containing group have been substituted with a monovalent heteroatom-containing group.

[0012] In the present invention, unless otherwise specified, the term "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "hydrocarbon group" includes both saturated and unsaturated hydrocarbon groups. The term "linear hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a linear structure, and includes both linear and branched hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it does not have to be composed only of an alicyclic structure, and may contain a linear structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and may contain a linear structure or an alicyclic structure as part of it.

[0013] On the other hand, in another embodiment, the present invention provides a step of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film; exposing the resist film by immersion exposure; and The present invention also relates to a method for forming a resist pattern, which includes a step of developing the exposed resist film.

[0014] The method for forming a resist pattern of the present invention includes a step using the above-described radiation-sensitive resin composition, and therefore it is possible to obtain a resist pattern that has good sensitivity, high water repellency, and few defects.

[0015] On the other hand, in another embodiment, the present invention provides The present invention relates to a water repellency improver comprising a resin A having a first structural unit represented by the following formula (2). [ka] (In formula (2), X is a divalent linking group. R is a hydrogen atom, a fluorine atom, or a monovalent hydrocarbon group that is unsubstituted or substituted with a halogen atom or an alkoxy group. R 1 and R 2 are each independently a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, or R 1 and R 2 are combined with each other together with the carbon atoms to which they are bonded to form a ring structure (a) having 3 to 20 ring members. R 3 is a fluorinated chain hydrocarbon group having 1 to 4 carbon atoms.

[0016] The water repellency improver of the present invention contains the resin A, and thus can easily impart, improve or enhance the water repellency of a resist film or the like. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0018] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "composition") contains a specified resin A, a resin B, a radiation-sensitive acid generator, and a solvent. The composition may contain other optional components as long as the effects of the present invention are not impaired. By including the specified resin A, the radiation-sensitive resin composition has good sensitivity and can form a resist pattern that is highly water-repellent and has few defects.

[0019] (Resin A) Resin A is a resin A having a first structural unit containing a partial structure represented by the above formula (1).

[0020] In the above formula (1), examples of the divalent linking group represented by X include divalent hydrocarbon groups having 1 to 20 carbon atoms, divalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, and groups in which one or more carbon atoms in these groups have been replaced with divalent groups such as -O-, -CO-, -COO-, -CONR'-, -S-, -CS-, -COS, and -CSO-. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0021] In the above formula (1), the above R 1 and R 2 Examples of the chain hydrocarbon groups having 1 to 40 carbon atoms represented by the formula (I) include linear or branched saturated hydrocarbon groups having 1 to 40 carbon atoms, and linear or branched unsaturated hydrocarbon groups having 1 to 40 carbon atoms.

[0022] In the above formula (1), the above R 1 and R 2 Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the following formula (I) are each independently cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.

[0023] In the above formula (1), the above R 1 and R 2Examples of the monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms represented by the formula (I) include, independently, aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0024] In the above formula (1), the above R 1 and R 2 Examples of the monovalent fluorinated hydrocarbon groups having 1 to 40 carbon atoms represented by the formula (I) include, independently, monovalent fluorinated chain hydrocarbon groups having 1 to 40 carbon atoms and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 40 carbon atoms.

[0025] In the above formula (1), the above R 1 and R 2 Examples of the ring structure (a) having 3 to 20 ring members constituted by combining these together with the carbon atoms to which they are bonded include alicyclic hydrocarbons having the above number of carbon atoms, and groups in which two hydrogen atoms have been removed from the same carbon atom in an alicyclic hydrocarbon having a structure in which one or more carbon atoms in the alicyclic hydrocarbon have been replaced with a divalent group such as -O-, -CO-, -COO-, -CONR'-, -S-, -CS-, -COS, or -CSO-.

[0026] In the above formula (1), the above R 3 Examples of the fluorinated chain hydrocarbon group having 1 to 4 carbon atoms represented by the formula (I) include a monovalent fluorinated chain hydrocarbon group having 1 to 4 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 4 carbon atoms.

[0027] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 4 carbon atoms include fluorinated alkyl groups such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a heptafluoro-n-propyl group; fluorinated alkenyl groups such as a trifluoroethenyl group and a pentafluoropropenyl group; Examples include fluorinated alkynyl groups such as a fluoroethynyl group and a trifluoropropynyl group.

[0028] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 4 carbon atoms include: Examples include fluorinated cycloalkyl groups such as a fluorocyclobutyl group.

[0029] In the above formula (1), the * indicates a linking site to the polymer main chain portion, and is preferably a covalent bond.

[0030] The first structural unit (hereinafter also referred to as "structural unit (1)") is preferably a structural unit represented by the following formula (2). [ka] (In formula (2), X and R 1 ~R 3 is the same as equation (1). R is a hydrogen atom, a fluorine atom, or a monovalent hydrocarbon group that is unsubstituted or substituted with a halogen atom or an alkoxy group.

[0031] In the above formula (2), the unsubstituted or halogen atom- or alkoxy-substituted monovalent hydrocarbon group represented by R is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of copolymerizability of a monomer containing the first structural unit.

[0032] In the first structural unit, X in the formula (2) is preferably a group represented by the following formula (2-1). [ka] (In formula (2-1), Z 1 and Z 2are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, a monovalent fluorinated hydrocarbon group, a group in which one or more carbon atoms in a monovalent hydrocarbon group or a monovalent fluorinated hydrocarbon group are replaced with a linking group represented by *-O-*, *-CO-*, *-COO-* or *-OCO-* (where * in the linking group represents a bond to a carbon atom), or Z 1 and Z 2 are bonded to each other together with the carbon atoms to which they are attached, forming a ring structure having 3 to 20 ring members. L is a single bond or a divalent organic group. n is an integer from 1 to 5.

[0033] In the above formula (2-1), Z 1 and Z 2 Examples of the monovalent hydrocarbon groups represented by the following formula (1) are each independently methyl, ethyl, and the like.

[0034] In the above formula (2-1), Z 1 and Z 2 Examples of the monovalent fluorinated hydrocarbon groups represented by the following formulas are each independently a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms.

[0035] In the above formula (2-1), the above Z 1 and Z 2 Examples of the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms.

[0036] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms include fluorinated alkyl groups such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a heptafluoro-n-propyl group; fluorinated alkenyl groups such as a trifluoroethenyl group and a pentafluoropropenyl group; Examples include fluorinated alkynyl groups such as a fluoroethynyl group and a trifluoropropynyl group.

[0037] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms include: fluorinated cycloalkyl groups such as a fluorocyclopentyl group, a difluorocyclopentyl group, a nonafluorocyclopentyl group, a fluorocyclohexyl group, a difluorocyclohexyl group, an undecafluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, and a fluoroisobornyl group; Examples include fluorinated cycloalkenyl groups such as a fluorocyclopentenyl group and a nonafluorocyclohexenyl group.

[0038] The fluorinated hydrocarbon group is preferably the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms, more preferably a monovalent fluorinated alkyl group having 1 to 8 carbon atoms, still more preferably a perfluoroalkyl group having 1 to 6 carbon atoms, and particularly preferably a linear perfluoroalkyl group having 1 to 6 carbon atoms.

[0039] In the above formula (2-1), Z 1 and Z 2 Examples of groups in which one or more carbon atoms in a monovalent fluorinated hydrocarbon group represented by the following formula are replaced by a linking group represented by *-O-* include, independently of one another, a methoxymethyl group and the like.

[0040] In the above formula (2-1), Z 1 and Z 2 Examples of groups in which one or more carbon atoms in a monovalent fluorinated hydrocarbon group represented by the following formula are replaced by a linking group represented by *-CO-* include, independently of one another, an acetyl group and the like.

[0041] In the above formula (2-1), Z 1 and Z 2Examples of groups in which one or more carbon atoms in a monovalent fluorinated hydrocarbon group represented by the formula (I) are replaced by a linking group represented by *-COO-* include, independently, a methoxycarbonyl group, an ethoxycarbonyl group, etc.

[0042] In the above formula (2-1), Z 1 and Z 2 Examples of groups in which one or more carbon atoms in a monovalent fluorinated hydrocarbon group represented by the following formula are replaced by a linking group represented by *-OCO-* include, independently of each other, a methyl carbonate group, etc.

[0043] In the above formula (2-1), the above Z 1 and Z 2 The ring structure (b) having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded is not particularly limited, as long as it is a group in which two hydrogen atoms have been removed from the same carbon atom constituting a carbon ring of a hydrocarbon having the above carbon number.

[0044] In the above formula (2-1), the divalent organic group represented by L is, for example, a substituted or unsubstituted divalent hydrocarbon group having 1 to 30 carbon atoms, -O-, -S-, -CO-, -COO-, -NR 20 -,-CONR 20 - or the like (R 20 represents a hydrogen atom or a monovalent hydrocarbon group (the same applies below), a divalent heterocyclic group, etc.

[0045] In the above formula (2-1), n ​​is an integer of 1 to 5, preferably 2 or 3.

[0046] Examples of the first structural unit include structural units represented by the following formulas (F-1) to (F-34) (hereinafter also referred to as "structural units (F-1) to (F-34)").

[0047] [ka] JPEG2026035870000006.jpg202120JPEG2026035870000007.jpg214145JPEG2026035870000008.jpg111130

[0048] The content of the first structural unit in the resin A is, for example, preferably 10 mol % or more, and more preferably 20 mol % or more, relative to all structural units constituting the resin A. Alternatively, it may be 100 mol %, and is preferably 90 mol % or less, and more preferably 80 mol % or less.

[0049] The resin A may further have a second structural unit (hereinafter also referred to as "structural unit (2)") represented by the following formula (3). [ka] (In formula (3), R 4 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 5 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 6 and R 7 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R 6 and R 7 are combined together with the carbon atoms to which they are bonded to form a divalent alicyclic group having 3 to 20 carbon atoms.

[0050] In the above formula (3), R 5 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula include a methyl group and an ethyl group.

[0051] In the above formula (3), R 6 and R 7 Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include, independently, a methyl group, an ethyl group, and the like.

[0052] In the above formula (3), R 6 and R 7 Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the following formula (I) are each independently exemplified by a cyclopentyl group, a cyclohexyl group, and the like.

[0053] In the above formula (3), R 6 and R 7 The divalent alicyclic group having 3 to 20 carbon atoms formed by combining these together with the carbon atom to which they are bonded is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom that constitutes a carbon ring of a hydrocarbon having the above carbon number.

[0054] Examples of the second structural unit include structural units represented by the following formulas (2-1) to (2-6) (hereinafter also referred to as "structural units (2-1) to (2-6)").

[0055] [ka]

[0056] In the above formulas (2-1) to (2-6), R 4 ~R 7 has the same meaning as in the above formula (2). i and j each independently represent an integer of 0 to 16. k is 0 to 1.

[0057] i and j are preferably 1. 5 is preferably a methyl group, an ethyl group or an isopropyl group.

[0058] The resin A may contain one type of structural unit (2) or a combination of two or more types.

[0059] When the resin A contains the second structural unit, the content of the second structural unit in the resin A is, for example, preferably 1 mol % or more, more preferably 5 mol % or more, relative to all structural units constituting the resin A. Also, the content is preferably 70 mol % or less, more preferably 60 mol % or less.

[0060] (Method for synthesizing resin A) The resin A can be synthesized, for example, by polymerizing the monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0061] Examples of the radical polymerization initiator include azo radical polymerization initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical polymerization initiators can be used alone or in combination of two or more.

[0062] Examples of the solvent used in the polymerization include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0063] The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0064] The molecular weight of the resin A is not particularly limited, but the weight average molecular weight (Mw) of the resin A measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the resin A is less than the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the resin A is greater than the upper limit, the developability of the resist film may be reduced.

[0065] The ratio (Mw / Mn) of Mw to the polystyrene equivalent number average molecular weight (Mn) of the resin A measured by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0066] The Mw and Mn of the resin A are values ​​measured by gel permeation chromatography (GPC) under the following conditions.

[0067] GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh Corporation) Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0068] The content of Resin A is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base resin described below, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0069] (Resin B) Resin B is a resin containing a structural unit having an acid-dissociable group (hereinafter, this resin will also be referred to as the "base resin"). Resin B is an aggregate of polymers having a structural unit containing an acid-dissociable group (hereinafter, also referred to as the "structural unit (I)"). The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and that dissociates under the action of an acid. The radiation-sensitive resin composition has excellent pattern formability because the resin contains the structural unit (I).

[0070] In addition to the structural unit (I), the base resin preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, which will be described later, and may also have structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0071] Structural Units The structural unit (I) is a structural unit containing an acid-dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, a structural unit represented by the following formula (4) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0072] [ka] (In formula (4), R 8 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 9 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 10 and R 11 are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R 10 and R 11 are combined together with the carbon atoms to which they are bonded to form a divalent alicyclic group having 3 to 20 carbon atoms.

[0073] In the above formula (4), R 9 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula include a methyl group and an ethyl group.

[0074] In the above formula (4), R 10 and R 11 Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include, independently, a methyl group, an ethyl group, and the like.

[0075] In the above formula (4), RR 10 and R 11 Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the following formula (I) are each independently exemplified by a cyclopentyl group, a cyclohexyl group, and the like.

[0076] In the above formula (4), R 10 and R 11 The divalent alicyclic group having 3 to 20 carbon atoms formed by combining these together with the carbon atom to which they are bonded is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom that constitutes a carbon ring of a hydrocarbon having the above carbon number.

[0077] Examples of the structural unit (I-1) include structural units represented by the following formulas (4-1) to (4-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)").

[0078] [ka]

[0079] In the above formulas (4-1) to (4-6), R 8 ~R 11 has the same meaning as in the above formula (4). i' and j' each independently represent an integer of 0 to 16. k' is 0 to 1.

[0080] i' and j' are preferably 1. 9 is preferably a methyl group, an ethyl group or an isopropyl group.

[0081] The base resin may contain one type of structural unit (I) or a combination of two or more types.

[0082] The content of the structural unit (I) (the total content when multiple types are included) relative to all structural units constituting the base resin is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0083] [Structural unit (II)] The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further including the structural unit (II), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Furthermore, the adhesion between a resist pattern formed from the base resin and a substrate can be improved.

[0084] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-10).

[0085] [ka]

[0086] In the above formula, R L1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4 and R L5 and may be combined together to form a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0087] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining these together with the carbon atoms to which they are bonded include R 1 and R 2Among divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula together with the carbon atoms to which they are bonded, groups having 3 to 8 carbon atoms can be mentioned. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0088] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0089] Of these, the structural unit (II) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0090] The content of the structural unit (II) is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, based on all structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less. By setting the content of the structural unit (II) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0091] [Structural unit (III)] The base resin optionally contains other structural units in addition to the structural units (I) and (II). Examples of the other structural units include a structural unit (III) containing a polar group (excluding those corresponding to the structural unit (II)). By further containing the structural unit (III), the base resin can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive resin composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0092] Examples of the structural unit (III) include structural units represented by the following formula:

[0093] [ka]

[0094] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0095] When the base resin has the structural unit (III) having the polar group, the content of the structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more, based on the total structural units constituting the base resin. Also, the content is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. By setting the content of the structural unit (III) within the above range, the lithography performance, such as resolution, of the radiation-sensitive resin composition can be further improved.

[0096] Structural Unit (IV) In addition to the structural unit (III) having the polar group, the base resin optionally contains a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both of these are collectively referred to as "structural unit (IV)"). The structural unit (IV) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This resin is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV. In this case, the resin preferably contains the structural unit (I) in addition to the structural unit (IV).

[0097] In this case, it is preferable to carry out polymerization in a state in which the phenolic hydroxyl group is protected with a protecting group such as an alkali-labile group, and then to obtain structural unit (IV) by deprotection through hydrolysis. The structural unit that gives structural unit (IV) upon hydrolysis is preferably represented by the following formula (6-1) or (6-2).

[0098] [ka]

[0099] In the above formulas (6-1) and (6-2), R 13 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 12 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 14 The monovalent hydrocarbon group having 1 to 20 carbon atoms is R 8 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0100] Above R 14 As the alkyl group, an alkyl group and an alkoxy group are preferred, and among these, a methyl group and a tert-butoxy group are more preferred.

[0101] In the case of a resin intended for exposure to radiation having a wavelength of 50 nm or less, the content of the structural unit (IV) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total structural units constituting the resin, and is preferably 70 mol % or less, more preferably 60 mol % or less.

[0102] (Method for synthesizing resin B) The resin B can be synthesized, for example, by polymerizing the monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0103] Examples of the radical polymerization initiator include azo radical polymerization initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical polymerization initiators can be used alone or in combination of two or more.

[0104] Examples of the solvent used in the polymerization include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more.

[0105] The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0106] The molecular weight of the base resin is not particularly limited, but the weight average molecular weight (Mw) of the base resin in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the base resin is below the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the base resin is above the upper limit, the developability of the resist film may be reduced.

[0107] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0108] As in the case of Resin A described above, the Mw and Mn of the base resin are values ​​measured using gel permeation chromatography (GPC).

[0109] The content of the base resin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0110] (other resins) The radiation-sensitive resin composition of this embodiment may contain a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin") as another resin different from the resin A. When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, thereby improving the water repellency of the surface of the resist film during immersion exposure.

[0111] The high-fluorine content resin preferably has, for example, a structural unit represented by the following formula (7) (hereinafter also referred to as "structural unit (V)"), and may also have the structural unit (I) or the structural unit (II) in the base resin, as necessary.

[0112] [ka]

[0113] In the above formula (7), R 15 is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH- or -OCONH-. 16 is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0114] Above R 15 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0115] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferred, and -COO- is more preferred.

[0116] Above R 16Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0117] Above R 16 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0118] Above R 16 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0119] When the high-fluorine-content resin has the structural unit (V), the content of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, based on the total structural units constituting the high-fluorine-content resin. Also, the content is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0120] The high-fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V): By having the structural unit (f-2), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0121] [ka]

[0122] The structural unit (VI) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of alkali to increase the solubility in an alkali developer (hereinafter simply referred to as an "alkali-dissociable group"). In both (x) and (y), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the hydrocarbon group are substituted with an organic group having a hetero atom. dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0123] When the structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. 1 is an oxygen atom, W 1 is A 1 is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has (x) an alkali-soluble group, it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (VI) having (x) an alkali-soluble group, A 1is an oxygen atom and W 1 It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0124] When the structural unit (VI) has an alkali-dissociable group (y), R F is a monovalent organic group having 1 to 30 carbon atoms, and A 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1 or R F is A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 1 to 20 carbon atoms E A carbonyl group is bonded to the end of the R F is an organic group having a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has (y) an alkali-dissociable group, the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, the affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit (VI) having (y) an alkali-dissociable group, A 1 is -COO-* and R F Or W 1 It is particularly preferred that both of them have a fluorine atom.

[0125] RC As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred.

[0126] R E When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and more preferably a group having a norbornane lactone structure.

[0127] When the high-fluorine-content resin has the structural unit (VI), the content of the structural unit (VI) is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more, based on all structural units constituting the high-fluorine-content resin. Also, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0128] Other structural units The high fluorine content resin may contain a structural unit having an alicyclic structure represented by the following formula (8) as a structural unit other than the structural units listed above. [ka] (In the above formula (8), R 1α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0129] In the above formula (8), R 2α Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0130] When the high-fluorine-content resin contains the structural unit having the alicyclic structure, the content of the structural unit having the alicyclic structure is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the total structural units constituting the high-fluorine-content resin, and is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less.

[0131] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0132] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the Mw / Mn is usually 5, and is preferably 3, more preferably 2, and even more preferably 1.9.

[0133] The content of the high-fluorine content resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, relative to 100 parts by mass of the base resin, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0134] The radiation-sensitive resin composition may contain one or more high-fluorine-content resins.

[0135] (Method for synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the synthesis method for resin A or the base resin described above.

[0136] (Radiation-sensitive acid generator) The radiation-sensitive resin composition of this embodiment further contains a radiation-sensitive acid generator that generates an acid upon irradiation (exposure) with radiation. When the base resin having the structural unit (I) and the resin A contain the structural unit (2), the acid generated from the radiation-sensitive acid generator upon exposure can dissociate the acid-dissociable groups in the structural unit (I) and the structural unit (2) to generate a carboxyl group or the like.

[0137] When the radiation-sensitive resin composition contains the radiation-sensitive acid generator, the polarity of the resin in the exposed area increases, and the resin in the exposed area becomes soluble in the developer in the case of alkaline aqueous solution development, while becoming poorly soluble in the developer in the case of organic solvent development.

[0138] Examples of the radiation-sensitive acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Among these, sulfonium salts and iodonium salts are preferred.

[0139] Examples of the acid generated upon exposure include those that generate sulfonic acids upon exposure. Examples of such acids include compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to the sulfo group. Among these, those having a cyclic structure are particularly preferred as radiation-sensitive acid generators.

[0140] These radiation-sensitive acid generators may be used alone or in combination of two or more. The content of the radiation-sensitive acid generator (when multiple types of radiation-sensitive acid generators are used in combination, the total content) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the base resin. Furthermore, the content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less, per 100 parts by mass of the base resin. This allows for excellent sensitivity, LWR performance, and CDU performance to be exhibited during resist pattern formation.

[0141] (acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an acid diffusion controller. The acid diffusion controller controls the diffusion of acid generated from the radiation-sensitive acid generator upon exposure in the resist film, thereby suppressing undesirable chemical reactions in unexposed regions. The storage stability of the resulting radiation-sensitive resin composition is also improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the exposure time between exposure and development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0142] Examples of the acid diffusion controller include a compound represented by the following formula (5) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

[0143] [ka]

[0144] In the above formula (5), R 22 , R 23 and R 24are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0145] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0146] Examples of the nitrogen-containing compound (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0147] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethylacrylamide; and the like.

[0148] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0149] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0150] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0151] In addition, a compound having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of such nitrogen-containing organic compounds having an acid-dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, and Nt-amyloxycarbonyl-4-hydroxypiperidine.

[0152] Furthermore, a photodegradable base that generates a weak acid upon exposure can also be suitably used as the acid diffusion controller. Examples of the photodegradable base include a compound containing a radiation-sensitive onium cation that decomposes upon exposure and an anion of a weak acid. In the photodegradable base, a weak acid is generated from a proton generated by decomposition of the radiation-sensitive onium cation and an anion of the weak acid in the exposed area, resulting in a decrease in acid diffusion controllability.

[0153] Examples of the photodegradable base include sulfonium salt compounds represented by the following formula (6-1) and iodonium salt compounds represented by the following formula (6-2).

[0154] [ka]

[0155] In the above formula (6-1) and formula (6-2), J + is a sulfonium cation, and U + is an iodonium cation. The sulfonium cation or iodonium cation is preferably represented by the following formulae (X-1) to (X-6). E- and Q- each independently represent OH-, R α -COO - , R α -SO3- It is an anion represented by R α is an alkyl group, an aryl group, or an aralkyl group. α A hydrogen atom in the aromatic ring of the aryl group or aralkyl group represented by the following formula may be substituted with a hydroxy group, a fluorine atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0156] [ka]

[0157] In the above formula (X-1), R a1 , R a2 and R a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q or -SR T or a ring structure formed by combining two or more of these groups. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. R P , R Q and R T are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R a1 ~R a3 and R P , R Q and R T If there are multiple R a1 ~R a3 and R P , R Q and R Tmay be the same or different.

[0158] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. n k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer between 0 and 7. R b1 If there are multiple, multiple R b1 may be the same or different, and multiple R b1 R may represent a ring structure formed by combining with each other. b2 L is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R b2 If there are multiple, multiple R b2 may be the same or different, and multiple R b2 may represent a ring structure formed by combining with each other, and q is an integer of 0 to 3. In the formula, S + The ring structure containing may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton.

[0159] In the above formula (X-3), R c1 , R c2 and R c3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0160] In the above formula (X-4), R g1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group.k is 0 or 1. n k2 When is 0, k10 is an integer between 0 and 4, and n k2 When is 1, k10 is an integer between 0 and 7. R g1 If there are multiple, multiple R g1 may be the same or different, and multiple R g1 R may represent a ring structure formed by combining with each other. g2 and R g3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 If there are multiple R g2 and R g3 may be the same or different.

[0161] In the above formula (X-5), R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, or a nitro group, or a ring structure formed by combining two or more of these groups. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 If there are multiple R d1 and R d2 may be the same or different.

[0162] In the above formula (X-6), R e1 and R e2are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0163] Examples of the substituent that may substitute the hydrogen atom of each of the above groups include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group (when substituting a hydrogen atom of a cycloalkyl group or an aromatic hydrocarbon group), an aryl group (when substituting a hydrogen atom of an alkyl group), an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, etc. Among these, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group is preferred, and an alkoxy group or an alkoxycarbonyl group is more preferred.

[0164] Examples of the photodegradable base include compounds represented by the following formula:

[0165] [ka]

[0166] Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate.

[0167] The lower limit of the content of the acid diffusion controller is preferably 3 parts by mass, more preferably 4 parts by mass, and even more preferably 5 parts by mass, relative to 100 parts by mass of the total of the radiation-sensitive acid generators, and the upper limit of the content is preferably 150 parts by mass, more preferably 120 parts by mass, and even more preferably 110 parts by mass.

[0168] By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion controller.

[0169] (solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the resin A, the resin B, the radiation-sensitive acid generator, and the like.

[0170] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0171] Examples of alcohol-based solvents include: Monoalcohol solvents having 1 to 18 carbon atoms, such as iso-propanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples include polyhydric alcohol partially etherified solvents obtained by etherifying some of the hydroxy groups of the above polyhydric alcohol solvents.

[0172] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples include polyhydric alcohol ether solvents obtained by etherifying the hydroxy groups of the above polyhydric alcohol solvents.

[0173] Examples of the ketone solvent include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone; Cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0174] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of the solvent include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0175] Examples of ester solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of suitable solvents include polyvalent carboxylic acid diesters such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0176] Examples of hydrocarbon solvents include Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0177] Among these, ester-based solvents and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents and lactone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0178] (Other optional ingredients) The radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0179] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which causes a crosslinking reaction in the resin component by an acid catalyst reaction in the bake step after the floodwise exposure step, thereby increasing the molecular weight of the resin component and reducing the solubility of the patternwise exposed areas in a developer. Examples of the functional groups include (meth)acryloyl groups, hydroxymethyl groups, alkoxymethyl groups, epoxy groups, and vinyl ether groups.

[0180] (Uneven distribution promoter) The uneven distribution promoter has the effect of more efficiently unevenly distributing the high-fluorine-content resin on the resist film surface. By incorporating this uneven distribution promoter into the radiation-sensitive resin composition, the amount of the high-fluorine-content resin added can be reduced compared to conventional methods. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress elution of components from the resist film into the immersion medium and perform immersion exposure at higher speeds through high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface, which suppresses immersion-related defects such as watermark defects. Examples of compounds that can be used as such uneven distribution promoters include low-molecular-weight compounds having a dielectric constant of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

[0181] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

[0182] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, and vinylene carbonate.

[0183] The nitrile compound may, for example, be succinonitrile.

[0184] The polyhydric alcohol may, for example, be glycerin.

[0185] The content of the uneven distribution accelerator is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and still more preferably 25 parts by mass or more, relative to 100 parts by mass of the total amount of resins in the radiation-sensitive resin composition. The content is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. The radiation-sensitive resin composition may contain one or more uneven distribution accelerators.

[0186] (surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products), Megafac F171, F173 (all manufactured by DIC), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.) The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0187] (alicyclic skeleton-containing compounds) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

[0188] Examples of the alicyclic skeleton-containing compound include: Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholate esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, etc. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of the resin.

[0189] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0190] Examples of sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0191] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing the resin A, the resin B, the radiation-sensitive acid generator, and optionally a high-fluorine-content resin, and a solvent in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter with a pore size of about 0.05 μm. The solids concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0192] <Method for forming a resist pattern> A method for forming a resist pattern according to one embodiment of the present invention includes: a step of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step of exposing the resist film by immersion exposure (hereinafter also referred to as an "exposure step"); and The method includes a step of developing the exposed resist film (hereinafter also referred to as a "developing step").

[0193] According to the method for forming a resist pattern, since the radiation-sensitive resin composition containing the resin A is used, it is possible to form a resist pattern with good sensitivity, high water repellency, and few defects. Each step will be described below.

[0194] [Resist film formation process] In this step (resist film formation step), a resist film is formed from the radiation-sensitive resin composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed, if necessary, to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 140°C, preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0195] When performing immersion exposure, a protective film for immersion exposure that is insoluble in the immersion liquid may be provided on the formed resist film, regardless of whether the radiation-sensitive resin composition contains a water-repellent polymer additive such as a high-fluorine-content resin, in order to prevent direct contact between the immersion liquid and the resist film. The protective film for immersion exposure may be a film formed using the water-repellency improving agent. The protective film for immersion exposure may be either a solvent-removable protective film that is removed with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-removable protective film that is removed simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-removable protective film for immersion exposure.

[0196] When the next exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural units (I) and (IV) as the base resin in the composition.

[0197] [Exposure process] In this step (the exposure step), the resist film formed in the resist film formation step is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). The radiation used for exposure may be, depending on the line width of the desired pattern, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet), X-rays, and gamma rays; or charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV being more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, being even more preferred.

[0198] When exposure is performed by immersion exposure, examples of the immersion liquid used include water and fluorine-based inert liquids. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible so as to minimize distortion of the optical image projected onto the film. However, particularly when the exposure light source is an ArF excimer laser (wavelength 193 nm), water is preferred for its availability and ease of handling, in addition to the above considerations. When water is used, a small proportion of an additive that reduces the surface tension of water and increases its surfactant power may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0199] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the resin or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0200] [Development process] In this step (the developing step), the resist film exposed in the exposure step is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse solution such as water or alcohol, and then dried.

[0201] In the case of alkaline development, the developer used for the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0202] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As ether solvents, glycol ether solvents are preferred, with ethylene glycol monomethyl ether and propylene glycol monomethyl ether being more preferred. As ester solvents, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As ketone solvents, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0203] As mentioned above, the developer may be either an alkaline developer or an organic solvent developer.

[0204] Examples of development methods include a method in which a substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (puddle method), a method in which developer is sprayed onto the surface of the substrate (spray method), and a method in which developer is continuously dispensed onto a substrate rotating at a constant speed while a developer dispensing nozzle is scanned at a constant speed (dynamic dispense method).

[0205] <Water repellency improver> A water repellency improver according to one embodiment of the present invention contains the above-mentioned resin A. The water repellency improver may contain other optional components as long as the effects of the present invention are not impaired. By containing the specified resin A, the water repellency improver can easily impart, improve, or enhance the water repellency of a resist film or the like.

[0206] Resin A is a resin A having a first structural unit containing a partial structure represented by the above formula (1). As the resin A, those described in the section on the radiation-sensitive resin composition can be used as appropriate.

[0207] The optional components include, for example, solvents, etc. As the solvents, those described in the section on the radiation-sensitive resin composition can be used as appropriate.

[0208] When a radiation-sensitive resin composition containing the water repellency improver of the present invention is used to perform immersion exposure using, for example, ArF excimer laser light, elution of the composition into the immersion liquid can be prevented or reduced, and contamination of the lens of the exposure light source can be prevented or reduced, for example.

[0209] Furthermore, when a radiation-sensitive resin composition containing the water repellency improver of the present invention is used to perform exposure to, for example, extreme ultraviolet (EUV) rays, it becomes possible to suppress or reduce defects caused by remaining droplets during a rinse treatment with fresh water after development.

[0210] An immersion upper layer film may also be formed on a resist film using an immersion upper layer film-forming composition containing the water repellency improver of the present invention and a solvent. [Example]

[0211] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below. In the following synthesis examples, unless otherwise specified, parts by mass mean values ​​when the total mass of the monomers used is taken as 100 parts by mass, and mol % means values ​​when the total number of moles of the monomers used is taken as 100 mol %.

[0212] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the prepared polymer were measured by gel permeation chromatography (GPC) using GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL" manufactured by Tosoh Corporation) under the following conditions. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn. Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40℃ Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0213] [ 13 C-NMR analysis] polymer 13 C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer ("JNM-Delta400" manufactured by JEOL Ltd.).

[0214] <Synthesis of [F] compound (monomer)> The monomers used in the synthesis of the polymer (E) in each example and examples of the synthesis method thereof are shown below.

[0215] [Synthesis Example 1] (Synthesis of Compound (F-1)) A reaction vessel was charged with 20.0 mmol of acetone, 30.0 mmol of (trifluoromethyl)trimethylsilane, 0.20 mmol of tetrabutylammonium fluoride, and 50 g of tetrahydrofuran, and the mixture was stirred at room temperature for 1 hour. Water was then added for dilution, followed by extraction with ethyl acetate, and the organic layer was separated. The resulting organic layer was washed with saturated aqueous sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the mixture was purified by atmospheric distillation to obtain a fluorinated alcohol in good yield.

[0216] To the fluorinated alcohol, 20.0 mmol of bromoacetyl bromide, 30.0 mmol of triethylamine, and 50 g of tetrahydrofuran were added and stirred at room temperature for 2 hours. After dilution with water, the mixture was extracted with ethyl acetate and the organic layer was separated. The resulting organic layer was washed with saturated aqueous ammonium chloride and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the bromo-form was obtained in good yield by purification by column chromatography.

[0217] To the bromo compound, 30.0 mmol of potassium carbonate, 30.0 mmol of methacrylic acid, and 50 g of dimethylformamide were added and stirred at 50°C for 4 hours. The reaction solution was then cooled to below 30°C, diluted with water, and then extracted with ethyl acetate to separate the organic layer. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the residue was purified by column chromatography to obtain a compound represented by the following formula (F-1) (hereinafter sometimes referred to as "compound (F-1)" or "monomer (F-1)") in good yield. The synthesis scheme for compound (F-1) is shown below.

[0218] [ka]

[0219] [Synthesis Examples 2 to 5] (Synthesis of Monomers (F-2) to (F-5)) Compounds represented by the following formulas (F-2) to (F-5) were synthesized in the same manner as in Synthesis Example 1, except that the raw materials and precursors were appropriately changed. (Hereinafter, the compounds represented by formulas (F-2) to (F-5) may be referred to as "compound (F-2)" to "compound (F-5)" or "monomer (F-2)" to "monomer (F-5)," respectively.)

[0220] [ka]

[0221] [Synthesis Example 6] (Synthesis of Compound (F-6)) To the bromo compound obtained in Synthesis Example 1 above, 25.0 mmol of zinc powder, 2.00 mmol of chlorotrimethylsilane, and 50 g of tetrahydrofuran were added and stirred at room temperature for 1 hour. Then, 20.0 mmol of acetone was added to the reaction solution and stirred at room temperature for an additional 6 hours. Then, a saturated aqueous solution of ammonium chloride was added to the reaction solution to terminate the reaction, followed by extraction with ethyl acetate and separation of the organic layer. The resulting organic layer was washed with a saturated aqueous solution of sodium chloride and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the resulting mixture was purified by column chromatography to obtain the alcohol compound in good yield.

[0222] To the alcohol, 30.0 mmol of triethylamine, 30.0 mmol of methacrylic acid chloride, and 50 g of tetrahydrofuran were added and stirred at 80°C for 1 hour. The reaction solution was then cooled to below 30°C, and a saturated aqueous ammonium chloride solution was added to terminate the reaction. Ethyl acetate was then added for extraction, and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the residue was purified by column chromatography to obtain a compound represented by the following formula (F-6) (hereinafter sometimes referred to as "compound (F-6)" or "monomer (F-6)") in good yield. The synthesis scheme for compound (F-6) is shown below.

[0223] [ka]

[0224] [Synthesis Examples 7 to 16] (Synthesis of Monomers (F-7) to (F-16)) Compounds represented by the following formulas (F-7) to (F-16) were synthesized in the same manner as in Synthesis Example 6, except that the raw materials and precursors were appropriately changed. (Hereinafter, the compounds represented by formulas (F-7) to (F-16) may be referred to as "compound (F-7)" to "compound (F-16)" or "monomer (F-7)" to "monomer (F-16)," respectively.)

[0225] [ka]

[0226] <Synthesis of Polymer [A] and Polymer [E]> The monomers used in the synthesis of each polymer in each example and comparative example are shown below.

[0227] [ka]

[0228] [Synthesis Example 17] (Synthesis of Polymer (A-1)) Monomer (M-1), monomer (M-2), and monomer (M-13) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 mol% relative to 100 mol% of the total monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours.

[0229] After the polymerization reaction was completed, the polymerization solution was cooled to 30°C or below with water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered off, and dried at 50°C for 10 hours to obtain a white powdery polymer (A-1) (yield: 82%). The Mw of the polymer (A-1) was 8,800, and the Mw / Mn was 1.50. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2) and (M-13) were 41.3 mol %, 13.8 mol % and 44.9 mol %, respectively.

[0230] [Synthesis Examples 18 to 27] (Synthesis of Polymers (A-2) to (A-11)) Polymers (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 17, except that the types and blending ratios of monomers shown in Table 1 below were used. The content (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained polymers are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[0231] [Table 1]

[0232] [Synthesis Example 28] (Synthesis of Polymer (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) at a molar ratio of 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours.

[0233] After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C using water cooling. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were then added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was completed, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to coagulate the resin. The resulting solid was filtered off and dried at 50°C for 13 hours to obtain a white powdery polymer (A-12) (yield: 80%). The Mw of the polymer (A-12) was 5,200, and the Mw / Mn was 1.60. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (M-1) and (M-18) were 51.3 mol % and 48.7 mol %, respectively.

[0234] [Synthesis Examples 29 to 31] (Synthesis of Polymers (A-13) to (A-15)) Polymers (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 28, except for using monomers of the types and blending ratios shown in Table 2. The content (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained polymers are also shown in Table 2.

[0235] [Table 2]

[0236] [Synthesis Example 32] (Synthesis of Polymer (E-1)) Monomer (F-1) and monomer (M-2) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 80 / 20 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours.

[0237] After the polymerization reaction was completed, the polymerized solution was cooled to 30°C or less with water. After the solvent was replaced with acetonitrile (400 parts by mass), hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This process was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of polymer (E-1) (yield: 70%). The Mw of polymer (E-1) was 5,100, and the Mw / Mn was 1.55. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (F-1) and (M-2) were 80.3 mol % and 19.7 mol %, respectively.

[0238] [Synthesis Examples 33 to 53] (Synthesis of Polymers (E-2) to (E-22)) Polymers (E-2) to (E-22) were synthesized in the same manner as in Synthesis Example 32, except that the types and blending ratios of monomers shown in Table 3 below were used. The content (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained polymers are also shown in Table 3 below.

[0239] [Table 3]

[0240] Comparative Synthesis Examples 54 to 70 (Synthesis of Polymers (E-23) to (E-39)) Polymers (E-23) to (E-39) were synthesized in the same manner as in Synthesis Example 32, except that the types and blending ratios of monomers shown in Table 4 below were used. The content (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained polymers are also shown in Table 4 below.

[0241] [Table 4]

[0242] <Preparation of Radiation-Sensitive Resin Composition> The components other than the polymer [A] and the polymer [E] used in the preparation of each radiation-sensitive resin composition are shown below.

[0243] [[B] Acid generator] B-1 to B-5: Compounds represented by the following formulas (B-1) to (B-5)

[0244] [ka]

[0245] [[C] Acid diffusion control agent] C-1 to C-5: Compounds represented by the following formulas (C-1) to (C-5)

[0246] [ka]

[0247] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-butyrolactone D-4: Ethyl lactate

[0248] [Preparation of Positive Radiation-Sensitive Resin Composition for ArF Exposure] [Example 1] 100 parts by mass of (A-1) as a polymer, 14.0 parts by mass of (B-1) as an acid generator, 5.0 parts by mass of (C-1) as an acid diffusion controller, 3.0 parts by mass (solid content) of (E-1) as a polymer, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) = 70 / 29 / 1 (mass ratio) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-1).

[0249] [Examples 2 to 48 and Comparative Examples 1 to 17] Except for using each component of the type and content shown in Table 5 below, radiation-sensitive resin compositions (J-2) to (J-48) and (CJ-1) to (CJ-17) were prepared in the same manner as in Example 1.

[0250] [Table 5]

[0251] [Formation of a resist pattern using an ArF exposure positive-type radiation-sensitive resin composition] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating (Brewer Science's ARC66) using a spin coater (Tokyo Electron Limited's CLEAN TRACK ACT12), followed by heating at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 100 nm. The positive radiation-sensitive resin composition for ArF exposure prepared above was coated onto this bottom anti-reflective coating using the spin coater, followed by pre-baking at 100°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 90 nm. This resist film was then exposed to light using an ArF excimer laser immersion exposure system (ASML's TWINSCAN XT-1900i) under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7) through a 40 nm line-and-space mask pattern. After exposure, PEB (post-exposure bake) was performed for 60 seconds at 100° C. Then, the resist film was alkaline-developed using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and further dried to form a positive resist pattern (40 nm line and space pattern).

[0252] <Evaluation> The resist patterns formed using the radiation-sensitive resin composition for ArF exposure were evaluated for sensitivity and the number of defects after development according to the methods described below. Furthermore, the receding contact angle of the resist film before ArF exposure was evaluated according to the method described below. The results are shown in Table 6 below. The resist patterns were measured using a scanning electron microscope (CG-5000, manufactured by Hitachi High-Technologies Corporation).

[0253] [sensitivity] In forming a resist pattern using the radiation-sensitive resin composition for ArF exposure, the exposure dose for forming a 40 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm 2 The sensitivity was 25 mJ / cm 2 The following are considered "good" and 25mJ / cm 2If it exceeded this, it was rated as "poor".

[0254] [Receding contact angle after PB] The receding contact angle of the resist film before ArF exposure in the above resist pattern formation method was measured using a DSA-10 manufactured by KRUS under an environment of room temperature 23° C., relative humidity 40%, and normal pressure according to the following procedure.

[0255] Water was ejected from the needle of the DSA-10 to form a 25 μL droplet on the resist film, and the droplet was then sucked into the needle at a rate of 10 μL / min for 90 seconds, while the contact angle was measured every second (a total of 90 times). The average value of the 20 contact angles measured after PB was calculated from the point at which the contact angle stabilized, and this was used as the receding contact angle (°). A receding contact angle of 70° or greater after PB was evaluated as "good," and one below 70° was evaluated as "poor."

[0256] [Number of development defects] The resist film was exposed to an optimum exposure dose to form a line-and-space pattern with a line width of 40 nm, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection system (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be originating from the resist film and those due to foreign matter of external origin, and the number of defects determined to be originating from the resist film was calculated. After development, the number of defects determined to be originating from the resist film was evaluated as "good" if the number of defects determined to be originating from the resist film was 15 or less, and as "poor" if the number of defects was more than 15.

[0257] [Table 6]

[0258] As is clear from the results in Table 6, the radiation-sensitive resin composition of the example had good sensitivity, receding contact angle performance after PB, and defect performance after development when used for ArF exposure. In contrast, in the comparative examples, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example is used for ArF exposure, a resist pattern with high sensitivity, high water repellency, and few defects can be formed.

[0259] [Preparation of Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 49] [A] 100 parts by mass of (A-12) as a polymer, [B] 15.0 parts by mass of (B-1) as an acid generator, [C] 10.0 parts by mass of (C-2) as an acid diffusion controller, [E] 4.0 parts by mass of (E-1) as a polymer, and 6,110 parts by mass of a mixed solvent of [D] (D-1) / (D-4) = 70 / 30 (mass ratio) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-49).

[0260] [Examples 50 to 72 and Comparative Examples 18 to 24] Except for using each component of the type and content shown in Table 7 below, the radiation-sensitive resin compositions (J-50) to (J-72) and (CJ-18) to (CJ-24) were prepared in the same manner as in Example 49.

[0261]

Table 7

[0262] [Formation of Resist Pattern Using Radiation-Sensitive Resin Composition for EUV Exposure] A 12-inch silicon wafer was coated with a composition for forming a bottom anti-reflective coating ("ARC66" manufactured by Brewer Science) using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited) and then heated at 205°C for 60 seconds to form a bottom anti-reflective coating with an average thickness of 105 nm. The radiation-sensitive resin composition for EUV exposure prepared above was coated onto this bottom anti-reflective coating using the spin coater, followed by post-baking at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. This resist film was then exposed to light using an EUV exposure system ("NXE3300" manufactured by ASML) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR02. After exposure, post-baking was performed at 120°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and then dried to form a positive resist pattern (32 nm line and space pattern).

[0263] <Evaluation> The sensitivity and LWR performance of the resist patterns formed using the radiation-sensitive resin composition for EUV exposure were evaluated according to the following methods. The results are shown in Table 8. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0264] [sensitivity] In forming a resist pattern using the radiation-sensitive resin composition for EUV exposure, the exposure dose for forming a 32 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm 2 The sensitivity was 25 mJ / cm 2 The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0265] [Number of development defects] The resist film was exposed to an optimum exposure dose to form a line-and-space pattern with a line width of 32 nm, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection system (KLA-Tencor's "KLA2810"). The measured defects were then classified into those determined to be originating from the resist film and those due to foreign matter of external origin, and the number of defects determined to be originating from the resist film was calculated. After development, the number of defects determined to be originating from the resist film was evaluated as "good" if the number of defects determined to be originating from the resist film was 15 or less, and as "poor" if the number of defects was more than 15.

[0266] [Table 8]

[0267] As is clear from the results in Table 8, the radiation-sensitive resin compositions of the Examples exhibited good sensitivity and post-development defect performance when used for EUV exposure. In contrast, the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive resin compositions of the Examples are used for EUV exposure, resist patterns with high sensitivity and few defects can be formed.

[0268] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using the composition] [Example 82] A radiation-sensitive resin composition (J-73) was prepared by mixing 100 parts by mass of (A-1) as the [A] polymer, 10.0 parts by mass of (B-4) as the [B] acid generator, 5.0 parts by mass of (C-3) as the [C] acid diffusion controller, 3.0 parts by mass (solids content) of (E-1) as the [E] polymer, and 3,230 parts by mass of a mixed solvent [D] with a mass ratio of (D-1) / (D-2) / (D-3) of 70 / 29 / 1. The mixture was filtered through a membrane filter having a pore size of 0.2 μm.

[0269] A resist film was formed in the same manner as in the formation of a resist pattern using a positive-tone radiation-sensitive resin composition for ArF exposure, except that the negative-tone radiation-sensitive resin composition for ArF exposure (J-73) prepared above was used as the radiation-sensitive resin composition, and the resist film was exposed to ArF and subjected to PEB. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative-tone resist pattern (40 nm line and space pattern).

[0270] The resist pattern using the negative-tone radiation-sensitive resin composition for ArF exposure and the resist film before ArF exposure were evaluated in the same manner as the evaluation of the resist pattern using the positive-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 73 was excellent in sensitivity, receding contact angle performance after PB, and post-development defect performance, even when a negative-tone resist pattern was formed by ArF exposure. [Industrial Applicability]

[0271] The radiation-sensitive resin composition of the present invention, the resist pattern forming method using the same, the water repellency improver, and the like can form a resist pattern that has good sensitivity to exposure light, high water repellency, and few defects. The polymer of the present invention can be suitably used as a polymer component of the radiation-sensitive resin composition. The compound of the present invention can be suitably used as a monomer for the polymer. Therefore, they can be suitably used in processing processes for semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. A resin having a first structural unit represented by the following formula (2): 【Chemistry 1】 (In formula (2), X is a divalent linking group. R is a hydrogen atom, a fluorine atom, or a monovalent hydrocarbon group that is unsubstituted or substituted with a halogen atom or an alkoxy group. R １ and R ２ are each independently a monovalent chain hydrocarbon group having 1 to 40 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, or R １ and R ２ are combined with each other together with the carbon atoms to which they are attached to form a ring structure (a) having 3 to 20 ring members. R ３ is a fluorinated chain hydrocarbon group having 1 to 4 carbon atoms.

2. The resin according to claim 1, wherein X in the first structural unit in the formula (2) is a group represented by the following formula (2-1): 【Chemistry 2】 (In formula (2-1), Z １ and Z ２ are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, a monovalent fluorinated hydrocarbon group, a group in which one or more carbon atoms in a monovalent hydrocarbon group or a monovalent fluorinated hydrocarbon group are replaced with a linking group represented by *-O-*, *-CO-*, *-COO-* or *-OCO-* (where * in the linking group represents a bond to a carbon atom), or Z １ and Z ２ are bonded to each other together with the carbon atoms to which they are attached, forming a ring structure having 3 to 20 ring members. L is a single bond or a divalent organic group. n is an integer from 1 to 5.

3. The resin according to claim 1 or 2, further comprising a second structural unit represented by the following formula (3): 【Transformation 3】 (In formula (3), R ４ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ５ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ６ and R ７ are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R ６ and R ７ are combined together with the carbon atoms to which they are bonded to form a divalent alicyclic group having 3 to 20 carbon atoms.

4. A water repellency improver comprising the resin according to any one of claims 1 to 3.

5. An immersion upper layer film-forming composition comprising the water repellency improver according to claim 4 and a solvent.

Images