Photoresist resin, method for producing photoresist resin, photoresist resin composition, and pattern forming method

Abstract

Provided are a resin which exhibits a high resist performance due to the reduction of components that are sparingly soluble in a resist solvent, and a method for producing the resin.　The present invention provides a photoresist resin which comprises an acrylic resin, and which has a turbidity in terms of polystyrene of 30 or less measured by the "Standard Methods for the Examination of Water" of Japan Water Works Association of the Ministry of Health, Labour and Welfare Notification No. 261 of 2003, when dissolved in propylene glycol monomethyl ether acetate such that the resin solids concentration is 5 weight%.

Description

[Technical field]

[0001] The present invention relates to a monomer, a resin, a resin composition, and a pattern forming method. This application claims priority to Japanese Patent Application No. 2019-122971, filed in Japan on July 1, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] In semiconductor manufacturing, lithography technology for pattern formation has undergone a dramatic transformation. Initially, i-line and g-line were used for exposure in lithography, and the line width of the pattern was wide, so the capacity of the semiconductors manufactured was low. However, recent technological developments have made it possible to use KrF excimer lasers with short wavelengths and ArF excimer lasers with even shorter wavelengths, and the line width has become dramatically finer.

[0003] Novolac-based or styrene-based resins have been used in exposure with a KrF excimer laser, but the above resins contain aromatic groups, and therefore have the problem of absorbing the laser light of an ArF excimer laser. For this reason, in exposure with an ArF excimer laser, resins that do not contain aromatic groups (for example, resins having an alicyclic skeleton) are used instead of resins that contain aromatic groups. The resins used in exposure with an ArF excimer laser are mainly acrylic resins. This is based on the application of a mechanism in which, when an acrylic resin containing a monomer unit of (meth)acrylic acid protected by a protecting group and a radiation-sensitive acid generator are used as an oil composition, the protecting group is eliminated by the acid generated by exposure to form a carboxyl group, which becomes alkali-soluble.

[0004] A typical method for producing an acrylic resin is a radical polymerization method using a monomer containing a (meth)acrylate compound, a radical polymerization initiator, and, if necessary, a chain transfer agent. As such a polymerization method, for example, the following dropping polymerization method is known (Patent Documents 1 and 2). [1] Method of preheating monomer and adding it dropwise [2] Method of adding monomer dropwise into polymerization solvent maintained at a constant temperature [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-269855 A [Patent Document 2] JP 2004-355023 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional dropping polymerization method, there is a tendency that an acrylic resin having a larger molecular weight than the target one is obtained. This is considered to be due to the fact that in the dropping polymerization method, unreacted monomers remain in the reaction system even after the polymerization reaction is completed. In other words, after the polymerization reaction is completed, the generated resin and the unreacted monomers polymerize with the passage of time, resulting in a larger molecular weight of the resin.

[0007] Generally, as the molecular weight of a resin increases, it becomes more difficult to dissolve the resin in a resist solvent. For example, when the content of a poorly soluble resin (i.e., a resin with a large molecular weight) in an acrylic resin increases, the turbidity of the resin solution increases when the resin is dissolved in a resist solvent. In addition to the molecular weight, various other characteristics of the resin, such as the molecular weight distribution, are thought to be factors that increase the poor solubility of the resin in a resist solvent. The present inventors have found that when the turbidity reaches a certain value, the resist performance of the resin deteriorates.

[0008] Therefore, an object of the present invention is to provide a resin that exhibits good resist performance due to its high solubility in a resist solvent, and a method for producing the resin. Another object of the present invention is to provide a composition containing the resin that exhibits high resist performance. Another object of the present invention is to provide a method for forming a fine pattern with high accuracy by using the composition. [Means for solving the problem]

[0009] As a result of intensive research to achieve the above object, the present inventors have found that by adding a specific polymerization inhibitor to the reaction solution after the polymerization step by the dropping polymerization method, the polymerization of the obtained resin with unreacted monomers is suppressed, and a resin having high solubility in a resist solvent is obtained. The present invention was completed based on these findings.

[0010] That is, the present invention provides a photoresist resin made of an acrylic resin, which, when dissolved in propylene glycol monomethyl ether acetate so that the resin solids concentration is 5% by weight, has a polystyrene-equivalent turbidity of 30 or less, as measured using the method described in the "Testing Method for Drinking Water" of the Japan Water Works Association, Ministry of Health, Labour and Welfare Notification No. 261 of 2003.

[0011] The resin is represented by the following formulas (a1) to (a4): [ka] (In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. 2 ~R 4 are the same or different and each represents an alkyl group having 1 to 6 carbon atoms which may have a substituent. 2 and R 3 may be bonded to each other to form a ring. 5 , R 6 R is the same or different and represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent. 7 -COOR c R c represents a tertiary hydrocarbon group which may have a substituent, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group. n represents an integer of 1 to 3. R a is Z 1and are the same or different and each represents an oxo group, an alkyl group, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, or a carboxy group which may be protected by a protecting group. p represents an integer of 0 to 3. Ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms. It is preferable that the polymerized unit contains at least one type of polymerized unit selected from the group consisting of polymerized units represented by the following formula:

[0012] The resin is represented by the following formulas (b1) to (b5): [ka] (In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom; A represents a single bond or a linking group; X represents a non-bond, a methylene group, an ethylene group, an oxygen atom, or a sulfur atom; Y represents a methylene group or a carbonyl group; Z represents a divalent organic group. 1 ~V 3 are the same or different and are -CH 2 -, [-C(=O)-], or [-C(=O)-O-]. However, V 1 ~V 3 At least one of the groups is [-C(=O)-O-]. 8 ~R 14 are the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group which may have a fluorine atom, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group. It is preferable that the polymerized unit contains at least one type of polymerized unit selected from the group consisting of polymerized units represented by the following formula:

[0013] The resin is represented by the following formula (c1): [ka] (In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom. A represents a single bond or a linking group. R b represents a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group. q represents an integer of 1 to 5. Ring Z 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms. It is preferable that the copolymer contains a polymer unit represented by the following formula:

[0014] The present invention also provides a method for producing the photoresist resin, comprising: a step of polymerizing the monomer by dropping a monomer or a solution containing a monomer in the presence of a polymerization initiator; and a step of adding 10 ppm or more of a polymerization inhibitor relative to the resin solid content contained in the reaction liquid after the polymerization step.

[0015] The polymerization inhibitor is preferably at least one selected from the group consisting of hydroquinones, phenols, benzoquinones, and N-oxyl compounds.

[0016] The present invention also provides a resin composition containing at least the above resin and a radiation-sensitive acid generator.

[0017] The present invention also provides a pattern forming method comprising at least the steps of applying the composition to a substrate to form a coating film, exposing the coating film to light, and then dissolving the coating film in an alkali. Effect of the Invention

[0018] The resin of the present invention exhibits high resist performance because the content of components hardly soluble in a resist solvent is reduced. Also, the composition of the present invention contains a resin having a reduced content of components hardly soluble in a resist solvent, so it exhibits high resist performance and, by using this, a fine pattern can be formed with high accuracy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] <Resin> The resin of the present invention is an acrylic resin for photoresist, characterized in that when dissolved in propylene glycol monomethyl ether acetate so as to give a resin solids concentration of 5% by weight, it has a polystyrene-equivalent turbidity (hereinafter sometimes simply referred to as "turbidity") of 30 or less, measured using the method described in the "Testing Method for Drinking Water" of the Japan Water Works Association, Ministry of Health, Labour and Welfare Notification No. 261 of 2003.

[0020] The turbidity of the resin of the present invention is not particularly limited as long as it is 30 or less, but for example, it is preferably 20 or less, more preferably 10 or less, further preferably 5 or less, and particularly preferably 3 or less.

[0021] An acrylic resin is defined as a homopolymer or copolymer containing an acrylic monomer as an essential component, that is, a polymer containing a structural unit derived from an acrylic monomer as an essential structural unit.

[0022] The resin of the present invention may have a group (sometimes referred to as an "acid-decomposable group") that is partially eliminated by the action of an acid to generate a polar group, whereby the polarity of the resin of the present invention increases by the action of an acid, and the solubility of the resin in an alkaline developer increases.

[0023] Examples of the polar group include acidic groups such as phenolic hydroxyl groups, carboxy groups, fluorinated alcohol groups (preferably hexafluoroisopropanol groups), sulfonic acid groups, sulfonamide groups, sulfonylimide groups, (alkylsulfonyl)(alkylcarbonyl)methylene groups, (alkylsulfonyl)(alkylcarbonyl)imide groups, bis(alkylcarbonyl)methylene groups, bis(alkylcarbonyl)imide groups, bis(alkylsulfonyl)methylene groups, bis(alkylsulfonyl)imide groups, tris(alkylcarbonyl)methylene groups, and tris(alkylsulfonyl)methylene groups, and alcoholic hydroxyl groups. Among these, carboxy groups, fluorinated alcohol groups (preferably hexafluoroisopropanol groups), and sulfonic acid groups are preferred.

[0024] The acid-decomposable group is preferably a group in which a hydrogen atom of the polar group is substituted with a group that is cleaved by an acid. I )(R II )(R III ), -C(R IV )(R V )(OR VI In the above formula, R I ~R III , R VI R each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. IV and R V R each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. I ~R III At least two of the groups may be bonded to each other to form a ring. IV and R V may be bonded to each other to form a ring.

[0025] The number of carbon atoms in the acid-decomposable group is not particularly limited, but is, for example, preferably at least 4, and more preferably at least 5. The upper limit of the number of carbon atoms is not particularly limited, but is preferably 20.

[0026] R I ~R VI The alkyl group is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group, an s-butyl group, a t-butyl group, a hexyl group, and an octyl group.

[0027] R I ~R VIThe cycloalkyl group may be a monocyclic hydrocarbon group or a polycyclic (bridged ring) hydrocarbon group. The monocyclic hydrocarbon group is preferably a cycloalkyl group having 3 to 8 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The polycyclic hydrocarbon group is preferably a cycloalkyl group having 6 to 20 carbon atoms, such as an adamantyl group, a norbornyl group, an isobornyl group, a camphanyl group, a dicyclopentyl group, an α-pinel group, a tricyclodecanyl group, a tetracyclododecyl group, and an androstanyl group. At least one carbon atom in the cycloalkyl group may be substituted with a heteroatom such as an oxygen atom.

[0028] R I ~R VI The aryl group is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthryl group.

[0029] R I ~R VI The aralkyl group is preferably an aralkyl group having 7 to 12 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0030] R I ~R VI The alkenyl group is preferably an alkenyl group having 2 to 8 carbon atoms, and examples thereof include a vinyl group, an allyl group, a butenyl group, and a cyclohexenyl group.

[0031] R I ~R III A ring formed by bonding at least two of the groups, and R IV and R V The ring formed by bonding with each other is preferably a cycloalkane ring. The cycloalkane ring is preferably a monocyclic cycloalkane ring such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, or a cyclohexane ring; or a polycyclic cycloalkane ring such as a norbornane ring, a tricyclodecane ring, a tetracyclododecane ring, or an adamantane ring.

[0032] In addition, R I ~R VI The alkyl group, cycloalkyl group, aryl group, aralkyl group, alkenyl group, and the cycloalkane ring in the above formula (I) may each have a substituent.

[0033] Of the above acid-decomposable groups, t-butyl group, t-amyl group, and groups represented by the following formulae (I) to (IV) are preferred.

[0034] [ka]

[0035] R in the above formulas (I) to (IV) 2 ~R 7 , R a , n, p, and ring Z 1 respectively represent R in the formulas (a1) to (a4) described later. 2 ~R 7 , R a , n, p, and ring Z 1 indicates the same thing.

[0036] The acid-decomposable group may be provided via a spacer. The spacer has the same linking group as exemplified and explained as A in formula (1) described later.

[0037] The resin of the present invention preferably contains an acid-decomposable group as a polymerization unit having an acid-decomposable group. Examples of the polymerization unit having an acid-decomposable group include a polymerization unit represented by the following formula (1).

[0038] [ka]

[0039] In the formula (1), R 1represents the acid-decomposable group. In addition, in the formula (1), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom. Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, pentyl, isoamyl, s-amyl, t-amyl, and hexyl groups. Examples of the alkyl group having 1 to 6 carbon atoms and a halogen atom include a group in which one or more hydrogen atoms constituting the alkyl group are replaced with a halogen atom (halo(C 1-6 ) alkyl group) and the like.

[0040] In the formula (1), A represents a single bond or a linking group. Examples of the linking group include a carbonyl group (-C(=O)-), an ether bond (-O-), an ester bond (-C(=O)-O-), an amide bond (-C(=O)-NH-), a carbonate bond (-OC(=O)-O-), a group in which a plurality of these are linked, and a group in which an alkylene group is linked to these. Examples of the alkylene group include linear or branched alkylene groups such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene groups, and divalent alicyclic hydrocarbon groups (particularly divalent cycloalkylene groups) such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene groups.

[0041] The polymerization unit represented by the formula (1) preferably contains at least one type of polymerization unit selected from the group consisting of polymerization units represented by the following formulae (a1) to (a4). The "at least one type of polymerization unit selected from the group consisting of polymerization units represented by the formulae (a1) to (a4)" may be referred to as "monomer unit a".

[0042] [ka]

[0043] In the polymerized units represented by the formulae (a1) to (a4), R, like R in the formula (1), represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. Among them, A in the formulae (a1) to (a4) is preferably a single bond or a group in which an alkylene group and a carbonyloxy group are bonded (alkylene-carbonyloxy group). R 2 ~R 4 are the same or different and each represents an alkyl group having 1 to 6 carbon atoms which may have a substituent. 2 and R 3 may be bonded to each other to form a ring. 5 , R 6 R is the same or different and represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent. 7 -COOR c R c represents a tertiary hydrocarbon group which may have a substituent, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group. n represents an integer of 1 to 3. When n is 2 or 3, R 7 may be the same or different. a is Z 1 and are the same or different and each represents an oxo group, an alkyl group, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, or a carboxy group which may be protected by a protecting group. p represents an integer of 0 to 3. Ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms. When p is 2 or 3, R a may be the same or different.

[0044] R a Examples of the alkyl group in the formula (I) include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, t-butyl, pentyl, isoamyl, s-amyl, t-amyl, and n-hexyl groups.

[0045] R a Examples of the hydroxyalkyl group in the formula (I) include hydroxymethyl, 2-hydroxyethyl, 1-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, and 6-hydroxyhexyl groups. 1-6 Examples of such groups include alkyl groups.

[0046] R a Examples of the protecting group that the hydroxy group and the hydroxyalkyl group in the formula (I) may have include C groups such as methyl, ethyl, and t-butyl groups. 1-4 Alkyl group; a group that forms an acetal bond together with the oxygen atom constituting a hydroxyl group (e.g., C such as methoxymethyl group) 1-4 Alkyl-OC 1-4 alkyl group; groups which form an ester bond together with the oxygen atom constituting a hydroxy group (for example, an acetyl group, a benzoyl group, etc.), and the like.

[0047] R a Examples of the protecting group for the carboxyl group in the formula (I) include methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, t-butyl, pentyl, isoamyl, s-amyl, t-amyl, and hexyl groups. 1-6 Examples of the group include an alkyl group, a 2-tetrahydrofuranyl group, a 2-tetrahydropyranyl group, and a 2-oxepanyl group.

[0048] R 2 ~R 6 Examples of the alkyl group having 1 to 6 carbon atoms in the formula include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, pentyl, isoamyl, s-amyl, t-amyl, and hexyl groups. 1-4 Alkyl groups are preferred, and C 1-3 Alkyl groups, more preferably C 1-2 It is an alkyl group.

[0049] R2 ~R 6 Examples of the substituent that the alkyl group having 1 to 6 carbon atoms may have include a halogen atom, a hydroxy group, a substituted hydroxy group (e.g., a C group such as a methoxy, ethoxy, or propoxy group). 1-4 Examples of the alkyl group having 1 to 6 carbon atoms and having a substituent include halo (C alkoxy group, etc.) in which one or more hydrogen atoms constituting the alkyl group are replaced with halogen atoms, such as trifluoromethyl and 2,2,2-trifluoroethyl groups. 1-6 ) alkyl groups, hydroxymethyl, 2-hydroxyethyl, methoxymethyl, 2-methoxyethyl, ethoxymethyl, 2-ethoxyethyl, cyanomethyl, and 2-cyanoethyl groups.

[0050] R 2 and R 3 When they are bonded to each other to form a ring, examples of the ring include an alicyclic hydrocarbon ring having 3 to 12 carbon atoms which may have a substituent.

[0051] R c Examples of the tertiary hydrocarbon group in the formula include a t-butyl group and a t-amyl group.

[0052] R c Examples of the substituent that the tertiary hydrocarbon group in the formula (I) may have include halogen atoms, hydroxy groups, substituted hydroxy groups (e.g., C groups such as methoxy, ethoxy, and propoxy groups). 1-4 alkoxy group, cyano group, etc.

[0053] The ring Z 1Examples of the alicyclic hydrocarbon ring having 3 to 20 carbon atoms in the formula (5.2.1.0) include cycloalkane rings having about 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 12 members), such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, or a cyclooctane ring; monocyclic alicyclic hydrocarbon rings such as cycloalkene rings having about 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 10 members), such as a cyclopropene ring, a cyclobutene ring, a cyclopentene ring, or a cyclohexene ring; an adamantane ring; a norbornane ring, a norbornene ring, a bornane ring, an isobornane ring, or a tricyclo[5.2.1.0 2,6 ] Decane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecane ring or other rings containing a norbornane ring or a norbornene ring; perhydroindene ring, decalin ring (perhydronaphthalene ring), perhydrofluorene ring (tricyclo[7.4.0.0 3,8 ]tridecane ring), perhydroanthracene ring, etc., in which the aromatic condensed rings of the polycyclic rings are hydrogenated (preferably completely hydrogenated); tricyclo[4.2.2.1 2,5 ]Undecane ring and other bicyclic, tricyclic, and tetracyclic bridged hydrocarbon rings (for example, bridged hydrocarbon rings having about 6 to 20 carbon atoms) and other bridged cyclic hydrocarbon rings having about 2 to 6 rings.

[0054] Specific examples of the monomer unit a include a monomer unit represented by the following formula: d represents a methyl group or a hydrogen atom, R e R represents a methyl group or a hydrogen atom. e The bonding position of R is not particularly limited, and e may be bonded to any one of the carbon atoms constituting the alicyclic hydrocarbon ring. e When the group has two or more R e may be the same or different. The monomer unit a can be introduced into the resin by polymerizing the corresponding unsaturated carboxylic acid ester.

[0055] [ka]

[0056] [ka]

[0057] As the polymerized unit represented by the formula (1), in addition to the polymerized unit represented by the monomer unit a, it is also possible to use a polymerized unit corresponding to an unsaturated carboxylic acid ester containing a lactone ring, in which an oxygen atom constituting an ester bond is bonded to the β-position of the lactone ring and at least one hydrogen atom is located at the α-position of the lactone ring (excluding a polymerized unit corresponding to the monomer unit b described below), and the like.

[0058] The polymerization unit represented by the formula (1) may be of only one type, or may be of two or more types in combination. The polymerization unit represented by the formula (1) preferably includes at least one type of polymerization unit selected from the group consisting of the polymerization units represented by the formulas (a1) to (a4). The polymerization unit represented by the formula (1) may be used in combination with at least one type of polymerization unit selected from the group consisting of the polymerization units represented by the formulas (a1) to (a4) and a polymerization unit represented by the formula (1) other than the at least one type of polymerization unit selected from the group consisting of the polymerization units represented by the formulas (a1) to (a4) (polymerization unit represented by other formula (1)). The polymerization unit represented by the other formula (1) may be, for example, R 1 is a group having a tertiary hydrocarbon group (for example, a t-butyl group, a t-amyl group, etc.), is preferred.

[0059] In addition, the resin of the present invention is a [-C(=O)-O-], [-S(=O) 2It is preferable that the resin contains an alicyclic skeleton having at least [-C(=O)-O-], [-S(=O)-OC(=O)-]. When the resin contains the alicyclic skeleton, it is possible to impart high substrate adhesion and etching resistance to the resin. It is preferable that the resin of the present invention contains the alicyclic skeleton as a polymerization unit having the alicyclic skeleton. Note that the [-C(=O)-O-], [-S(=O) 2 A polymerization unit containing an alicyclic skeleton having at least [—O—] or [—C(═O)—O—C(═O)—] may be referred to as a “monomer unit b”.

[0060] The monomer unit b preferably contains at least one type of polymerization unit selected from the group consisting of polymerization units represented by the following formulae (b1) to (b5). In the following formulae (b1) to (b5), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. X represents a non-bond, a methylene group, an ethylene group, an oxygen atom, or a sulfur atom. Y represents a methylene group or a carbonyl group. Z represents a divalent organic group (for example, an alkylene group exemplified and explained as an alkylene group which may be contained in A in the polymerization units represented by the formulae (a1) to (a4) (particularly, a linear alkylene group having 1 to 3 carbon atoms), etc.). V 1 ~V 3 are the same or different and are -CH 2 -, [-C(=O)-], or [-C(=O)-O-]. However, V 1 ~V 3 At least one of the groups is [-C(=O)-O-]. 8 ~R 14 are the same or different and represent a hydrogen atom, a fluorine atom, an alkyl group which may have a fluorine atom, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group.

[0061] [ka]

[0062] Examples of R and A in the polymerization units represented by formulae (b1) to (b5) include the same examples as those of R and A in the polymerization units represented by formulae (a1) to (a4). 8 ~R 14 The alkyl group, the hydroxy group which may be protected by a protecting group, the hydroxyalkyl group which may be protected by a protecting group, and the carboxy group which may be protected by a protecting group in the polymer units represented by the formulas (a1) to (a4) are each independently selected from R a Examples similar to those in

[0063] R 8 ~R 14 Examples of the alkyl group having a fluorine atom in the formula (I) include a group in which one or more hydrogen atoms constituting the alkyl group are replaced with a fluorine atom, such as a trifluoromethyl group or a 2,2,2-trifluoroethyl group [fluoro(C 1-6 ) alkyl group] and the like.

[0064] In the polymerization units represented by the formulas (b1) to (b4), 8 ~R 11 Each of the R 8 ~R 11 When the group has two or more R 8 ~R 11 may be the same or different.

[0065] Among the monomer units b, those represented by formula (b1) and R 8 is a cyano group, a group having an amide group, a group having an imide group, or a fluoro(C 1-6The polymerization units represented by formula (b1), (b2), (b3) and (b4) are preferable in that they can impart excellent substrate adhesion and etching resistance to the resin, have excellent solubility in an alkaline developer, and can form fine patterns with high precision.

[0066] In the formula (b1), R 8 is a cyano group, a group having an amide group, a group having an imide group, or a fluoro(C 1-6 ) When R is an electron-withdrawing group such as an alkyl group, 8 is particularly preferably bonded to at least the carbon atom marked with * in formula (b1).

[0067] Specific examples of the monomer unit b include polymerization units represented by the following formulas: d represents a methyl group or a hydrogen atom. The monomer unit b can be introduced into the resin by polymerizing a corresponding unsaturated carboxylic acid ester.

[0068] [ka]

[0069] [ka]

[0070] The resin of the present invention may further contain a monomer unit c. The monomer unit c is a polymerized unit represented by the following formula (c1). When the resin of the present invention contains the monomer unit c as a polymerized unit, the photoresist resin can be provided with higher transparency and etching resistance. In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom. A represents a single bond or a linking group. R brepresents a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group, among which a hydroxy group and a cyano group are preferred. q represents an integer of 1 to 5. Ring Z 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms. When q is an integer of 2 to 5, 2 to 5 R b may be the same or different.

[0071] [ka]

[0072] Examples of R and A in the polymerization unit represented by formula (c1) include the same examples as those of R and A in the polymerization units represented by formulas (a1) to (a4). b The hydroxy group which may be protected by a protecting group, the hydroxyalkyl group which may be protected by a protecting group, and the carboxy group which may be protected by a protecting group in the polymer units represented by the formulas (a1) to (a4) are each independently selected from R a Examples similar to those in

[0073] Ring Z in the polymerization unit represented by formula (c1) 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms, and examples thereof include cycloalkane rings having about 6 to 20 members (preferably 6 to 15 members, particularly preferably 6 to 12 members) such as a cyclohexane ring or a cyclooctane ring; monocyclic alicyclic hydrocarbon rings such as a cycloalkene ring having about 6 to 20 members (preferably 6 to 15 members, particularly preferably 6 to 10 members) such as a cyclohexene ring; an adamantane ring; a norbornane ring, a norbornene ring, a bornane ring, an isobornane ring, a tricyclo[5.2.1.0 2,6 ] Decane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecane ring or other rings containing a norbornane ring or a norbornene ring; perhydroindene ring, decalin ring (perhydronaphthalene ring), perhydrofluorene ring (tricyclo[7.4.0.0 3,8]tridecane ring), perhydroanthracene ring, etc., in which the aromatic condensed rings of the polycyclic rings are hydrogenated (preferably completely hydrogenated); tricyclo[4.2.2.1 2,5 Examples of the bridged cyclic hydrocarbon ring include a bridged cyclic hydrocarbon ring having about 2 to 6 rings, such as a bridged cyclic hydrocarbon ring having about 2, 3 or 4 rings (for example, a bridged hydrocarbon ring having about 6 to 20 carbon atoms) such as an undecane ring. 2 Among these, a norbornane ring or a ring containing a norbornene ring, and an adamantane ring are preferable.

[0074] Specific examples of the monomer unit c include a polymerization unit represented by the following formula: d represents a methyl group or a hydrogen atom. The monomer unit c can be introduced into the resin by polymerizing a corresponding unsaturated carboxylic acid ester.

[0075] [ka]

[0076] The resin of the present invention preferably contains at least one monomer unit selected from the group consisting of the monomer unit a, the monomer unit b, and the monomer unit c. In this case, the content of the monomer unit a in the resin of the present invention is, for example, 1 to 99 mol%, preferably 5 to 95 mol%, based on all monomer units constituting the resin. When the resin of the present invention has the monomer unit b, the content of the monomer unit b is, for example, 1 to 99 mol%, preferably 5 to 95 mol%, based on all monomer units constituting the resin. When the resin of the present invention has the monomer unit c, the content of the monomer unit c is, for example, 1 to 99 mol%, preferably 5 to 95 mol%, based on all monomer units constituting the resin.

[0077] The weight average molecular weight (Mw) of the resin of the present invention is not particularly limited, but is preferably, for example, 1000 to 50000, and more preferably, 3000 to 20000. The molecular weight distribution (ratio of weight average molecular weight to number average molecular weight: Mw / Mn) of the resin of the present invention is not particularly limited as long as it is 3.5 or less, but is preferably, for example, 1.1 to 3.0, and more preferably, 1.2 to 2.5. In this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured, for example, by GPC using polystyrene as a standard substance, and are preferably measured by the method used in the examples.

[0078] The acid value of the resin of the present invention is not particularly limited, but is preferably 0.10 mmol / g or less, more preferably 0.05 mmol / g or less, and even more preferably 0.03 mmol / g or less. When the acid value is 0.10 mmol / g or less, the acid decomposable group in the resin is protected without being removed, so that the resin has excellent resist performance and good stability over time. The lower limit of the acid value is not particularly limited, but is, for example, 0 mmol / g.

[0079] <Resin manufacturing method> The method for producing the resin of the present invention is not particularly limited, and examples thereof include a dropping polymerization method. Examples of the dropping polymerization method include a method including a step of dropping a monomer or a solution containing a monomer in the presence of a polymerization initiator to polymerize the monomer (hereinafter, sometimes referred to as a "polymerization step"). More specifically, examples of the dropping polymerization method include a method including a step of dropping a solution containing a polymerization initiator and a monomer, and a step of dropping a monomer or a solution containing a monomer into a solution containing a polymerization initiator. In addition to the polymerization initiator, the dropping polymerization method may be performed in the presence of a chain transfer agent. Examples of the monomer include monomers corresponding to the monomer unit a, the monomer unit b, and the monomer unit c.

[0080] In addition, in the resin manufacturing method of the present invention, it is preferable to include a step of adding a polymerization inhibitor to the reaction liquid after the polymerization step (hereinafter, sometimes referred to as a "polymerization suppression step"), since this allows a resin that is highly soluble in a resist solvent to be obtained.

[0081] As the polymerization initiator, a known radical polymerization initiator can be used, for example, an azo compound, a peroxide compound, or a redox compound. In particular, dimethyl-2,2'-azobisisobutyrate, azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), t-butyl peroxypivalate, di-t-butyl peroxide, iso-butyryl peroxide, lauroyl peroxide, succinic acid peroxide, dicinnamyl peroxide, di-n-propyl peroxydicarbonate, t-butyl peroxyallyl monocarbonate, benzoyl peroxide, hydrogen peroxide, ammonium persulfate, and the like are preferred.

[0082] The amount of the polymerization initiator used is not particularly limited as long as it is an amount necessary to obtain a resin having a desired molecular weight distribution, and is, for example, 0.01 to 30 parts by weight, preferably 0.2 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight relative to the total amount (100 parts by weight) of the monomers.

[0083] The chain transfer agent may be a known chain transfer agent used in radical polymerization. Examples of the chain transfer agent include thiols (n-dodecyl mercaptan, n-octyl mercaptan, n-butyl mercaptan, tert-butyl mercaptan, n-lauryl mercaptan, mercaptoethanol, mercaptopropanol, triethylene glycol dimercaptan, etc.), thiolic acid and its esters (mercaptopropionic acid, thiobenzoic acid, thioglycolic acid, thiomalic acid, etc., and alkyl esters thereof), alcohols (isopropyl alcohol, etc.), amines (dibutylamine, etc.), hypophosphites (sodium hypophosphite, etc.), α-methylstyrene dimer, turbinolene, myrcene, limonene, α-pinene, β-pinene, etc.

[0084] The amount of the chain transfer agent used is not particularly limited, but is preferably 0.001 to 100 mol, more preferably 0.01 to 50 mol, even more preferably 0.1 to 30 mol, and particularly preferably 1 to 10 mol, relative to the total amount of monomers (100 mol). The amount of the chain transfer agent used is not particularly limited, but is preferably 0.1 to 100 parts by weight, more preferably 0.5 to 50 parts by weight, and even more preferably 1 to 25 parts by weight, relative to the total amount of monomers (100 parts by weight).

[0085] The polymerization step may be carried out without a solvent or in the presence of a polymerization solvent. Examples of the polymerization solvent include glycol-based solvents (the glycol-based compounds), ester-based solvents, ketone-based solvents, ether-based solvents, amide-based solvents, sulfoxide-based solvents, monohydric alcohol-based solvents (the monohydric alcohol-based compounds), hydrocarbon-based solvents, and mixtures thereof. Examples of the glycol solvent include propylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether acetate, in addition to the glycol-based compounds. Examples of the ester-based solvent include lactate ester-based solvents such as ethyl lactate; propionate ester-based solvents such as methyl 3-methoxypropionate; and acetate ester-based solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. Examples of the ketone-based solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, and cyclohexanone. Examples of ether-based solvents include chain ethers such as diethyl ether, diisopropyl ether, dibutyl ether, and dimethoxyethane; and cyclic ethers such as tetrahydrofuran and dioxane. Examples of amide-based solvents include N,N-dimethylformamide. Examples of sulfoxide-based solvents include dimethyl sulfoxide. Examples of hydrocarbon-based solvents include aliphatic hydrocarbons such as pentane, hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and aromatic hydrocarbons such as benzene, toluene, and xylene.

[0086] Preferred polymerization solvents include glycol-based solvents such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate; ester-based solvents such as ethyl lactate; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, and cyclohexanone; and mixed solvents thereof.

[0087] The dropping of the monomer-containing solution may be continuous (dropping over a certain period of time) or intermittent (dropping in several separate portions). The dropping speed, etc. may be changed once or more during the dropping.

[0088] The total dropping time of the monomer-containing solution (the time from the start of the dropping to the end of the dropping) varies depending on the polymerization temperature, the type of monomer, etc., but is generally 1 to 10 hours, preferably 2 to 9 hours, and more preferably 3 to 8 hours.

[0089] The polymerization temperature is not particularly limited, but is, for example, preferably 30 to 150° C., more preferably 50 to 120° C., and further preferably 60 to 100° C. The polymerization temperature may be changed one or more times within the above polymerization temperature range during the polymerization.

[0090] In the polymerization step, after the completion of the dropping, a maturing time may be provided. The maturing time is not particularly limited, but is preferably, for example, 0.5 to 10 hours, and more preferably 1 to 5 hours.

[0091] In the present invention, it is preferable to include a polymerization suppression step, since a resin having high solubility in a resist solvent can be obtained. That is, in the present invention, it is preferable to include a step of adding a specific amount of a polymerization inhibitor to the reaction liquid obtained by the polymerization step, thereby suppressing polymerization of the resin and unreacted monomer contained in the reaction liquid over time and reducing the generation of a poorly soluble resin.

[0092] In the polymerization suppression step, the polymerization inhibitor may be added to the reaction liquid obtained in the polymerization step without cooling it, or the polymerization inhibitor may be added after cooling. Here, cooling means, for example, lowering the reaction liquid to room temperature (23° C.) or lower. Examples of the cooling method include air cooling and water cooling.

[0093] The polymerization inhibitor is not particularly limited, and examples thereof include hydroquinones such as hydroquinone, methylhydroquinone, t-butylhydroquinone, and 2,5-di-t-butylhydroquinone; phenols such as 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol, 2-t-butyl-4,6-dimethylphenol, and 4-methoxyphenol (methoquinone); p-benzoquinone, chloro-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, and 2,5-dichloro-p-benzoquinone. quinone, 2,6-dichloro-p-benzoquinone, methoxy-p-benzoquinone, methyl-p-benzoquinone, tetrabromo-p-benzoquinone, tetrachloro-p-benzoquinone and other benzoquinones; 4-amino-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-cyano-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-hydroxy-2,2,6,6-tetramethyl Piperidine 1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxybenzoic acid, 2-hydroxy-2-azaadamantane, 4-isothiocyanato-2,2,6,6-tetramethylpiperidine, 4-(2-iodoacetamido)-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-[2-[2-(4-iodophenoxy)ethoxy]carbonyl]benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-methyl N-oxyl compounds such as tacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine 1-oxyl, and 2,2,6,6-tetramethyl-4-(2-propynyloxy)piperidine 1-oxyl; catechols such as 4-t-butylcatechol; nitro compounds such as o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, 1,3,5-trinitrobenzene, 1,3,5-trinitroanisole, and 1,3,5-trinitrotoluene;Examples of the inhibitors include nitroso compounds such as ammonium nitrosophenylhydroxylamine and aluminum nitrosophenylhydroxylamine; amines such as diethylhydroxylamine and diphenylamine; phenothiazine; 1,1-diphenyl-2-picrylhydrazyl; and inorganic polymerization inhibitors such as copper chloride, copper sulfate, and iron sulfate. Among these, hydroquinones and phenols are preferred because they are generally contained as polymerization inhibitors in raw materials for resist applications, i.e., monomers for producing resins for resists, and therefore are considered to have little effect on lithography performance. These can be used alone or in combination of two or more.

[0094] The amount of the polymerization inhibitor used is not particularly limited, but is, for example, preferably 10 ppm or more, more preferably 50 to 2000 ppm, even more preferably 100 to 1000 ppm, and most preferably 200 to 500 ppm, based on the resin solid content contained in the reaction liquid after the polymerization step.

[0095] The resin produced in the polymerization step or the resin obtained through the polymerization suppression step can be recovered, for example, by precipitation (including reprecipitation). For example, the polymerization solution (polymer dope) is added to a solvent (precipitation solvent) to precipitate the resin, or the resin is dissolved again in an appropriate solvent and this solution is added to a solvent (reprecipitation solvent) to reprecipitate, or a solvent (reprecipitation solvent or polymerization solvent) is added to the polymerization solution (polymer dope) to dilute it, thereby obtaining the target resin. The precipitation or reprecipitation solvent may be either an organic solvent or water, or may be a mixed solvent.

[0096] As the precipitation or reprecipitation solvent, a well-known or conventional solvent can be used, and is not particularly limited. The precipitation or reprecipitation solvent may be the same solvent as the polymerization solvent, or may be a different solvent. Examples of the precipitation or reprecipitation solvent include the organic solvents exemplified as the polymerization solvent (glycol solvents, ester solvents, ketone solvents, ether solvents, amide solvents, sulfoxide solvents, monohydric alcohol solvents, and hydrocarbon solvents); halogenated hydrocarbons (halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride; halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene); nitro compounds (nitromethane, nitroethane, and the like); nitriles (acetonitrile, benzonitrile, and the like); carbonates (dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, and the like); carboxylic acids (acetic acid, and the like); and mixed solvents containing these solvents.

[0097] Among them, the precipitation or reprecipitation solvent is preferably a solvent containing at least a hydrocarbon (particularly, an aliphatic hydrocarbon such as hexane or heptane) or an alcohol (particularly, methanol, ethanol, propanol, isopropyl alcohol, butanol, etc.). In such a solvent containing at least a hydrocarbon, the ratio of the hydrocarbon (e.g., an aliphatic hydrocarbon such as hexane or heptane) to the other solvent (e.g., an ester such as ethyl acetate) is, for example, the former / latter (volume ratio; 25°C)=10 / 90 to 99 / 1, preferably the former / latter (volume ratio: 25°C)=30 / 70 to 98 / 2, and more preferably the former / latter (volume ratio: 25°C)=50 / 50 to 97 / 3.

[0098] As the precipitation or reprecipitation solvent, a mixed solvent of alcohol (particularly, methanol) and water, or a mixed solvent of a glycol-based solvent (particularly, polyethylene glycol) and water is also preferred. In this case, the ratio (volume ratio; 25°C) of the organic solvent (alcohol or glycol-based solvent) to water is, for example, the former / latter (volume ratio; 25°C)=10 / 90 to 99 / 1, preferably the former / latter (volume ratio: 25°C)=30 / 70 to 98 / 2, and more preferably the former / latter (volume ratio: 25°C)=50 / 50 to 97 / 3.

[0099] The resin obtained by precipitation (including reprecipitation) is subjected to a rinsing process or a process in which the resin is loosened and dispersed in a solvent while being stirred and washed (sometimes called a "repulping process"). A rinsing process may be performed after the repulping process. By repulping the resin produced by polymerization with a solvent or rinsing it, residual monomers, low molecular weight oligomers, and the like adhering to the resin can be efficiently removed.

[0100] In the manufacturing method of the present invention, the repulping and rinsing treatment solvents are preferably solvents containing at least a hydrocarbon (particularly, an aliphatic hydrocarbon such as hexane or heptane), an alcohol (particularly, methanol, ethanol, propanol, isopropyl alcohol, butanol, etc.), or an ester (particularly, ethyl acetate, etc.).

[0101] After the precipitation (including reprecipitation), repulping, or rinsing, the solvent may be removed by decantation, filtration, or the like, as necessary, and a drying treatment may be carried out.

[0102] <Resin composition> The resin composition of the present invention contains at least the resin of the present invention and a radiation-sensitive acid generator.

[0103] The radiation-sensitive acid generator can be a conventional or known compound that efficiently generates an acid by exposure to radiation such as visible light, ultraviolet light, far ultraviolet light, electron beams, and X-rays, and is a compound consisting of a mother nucleus and an acid to be generated. Examples of the mother nucleus include onium salt compounds such as iodonium salts, sulfonium salts (including tetrahydrothiophenium salts), phosphonium salts, diazonium salts, and pyridinium salts, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, disulfonyldiazomethane compounds, disulfonylmethane compounds, oxime sulfonate compounds, and hydrazine sulfonate compounds. Examples of the acid generated by exposure include alkyl or fluorinated alkylsulfonic acids, alkyl or fluorinated alkyl carboxylic acids, and alkyl or fluorinated alkylsulfonylimide acids. These may be used alone or in combination of two or more.

[0104] The amount of the radiation-sensitive acid generator used can be appropriately selected depending on the strength of the acid generated by irradiation with radiation and the ratio of each repeating unit in the resin, and can be selected, for example, from the range of 0.1 to 30 parts by weight, preferably 1 to 25 parts by weight, and more preferably 2 to 20 parts by weight, per 100 parts by weight of the resin.

[0105] The resin composition can be prepared, for example, by mixing the resin and the radiation-sensitive acid generator in a solvent for resist. The solvent for resist can be any of the glycol solvents, ester solvents, ketone solvents, and mixtures thereof exemplified above as the polymerization solvent.

[0106] The resin composition has a resin concentration of, for example, 3 to 40% by weight. The resin composition may contain an alkali-soluble component such as an alkali-soluble resin (for example, a novolac resin, a phenol resin, an imide resin, or a carboxyl group-containing resin), a colorant (for example, a dye), etc.

[0107] <Pattern formation method> The resin composition of the present invention is applied onto a base material or a substrate, dried, and then exposed to light through a predetermined mask on the coating film (resist film) (or further baked after exposure) to form a latent image pattern, followed by alkali dissolution, whereby a fine pattern having excellent swelling resistance can be formed with high precision.

[0108] Examples of the base material or substrate include silicon wafers, metals, plastics, glass, ceramics, etc. The resin composition can be applied using a conventional coating means such as a spin coater, a dip coater, a roller coater, etc. The thickness of the coating film is, for example, preferably 0.05 to 20 μm, more preferably 0.1 to 2 μm.

[0109] For exposure, radiation such as visible light, ultraviolet light, far ultraviolet light, electron beams, and X-rays can be used.

[0110] Exposure causes the radiation-sensitive acid generator to generate an acid, which quickly removes protective groups (acid-decomposable groups) such as carboxy groups from polymer units (repeating units having an acid-decomposable group) in the resin composition that become alkali-soluble due to the action of the acid, generating carboxy groups that contribute to solubilization, etc. Therefore, a predetermined pattern can be formed with high accuracy by development with an alkaline developer. EXAMPLES

[0111] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the resin were determined by GPC measurement (gel permeation chromatography) using tetrahydrofuran solvent. Polystyrene was used as a standard sample, and a refractometer (RI detector) was used as a detector. The GPC measurement was performed using three Showa Denko K.K. columns (trade name "KF-806L") connected in series under the conditions of a column temperature of 40°C, an RI temperature of 40°C, and a tetrahydrofuran flow rate of 0.8 mL / min. The molecular weight distribution (Mw / Mn) was calculated from the measured values.

[0112] Example 1 (Preparation of Resin A-1) In a round-bottom flask equipped with a reflux condenser, a stirrer, and a three-way cock, 34.0 g of propylene glycol monomethyl ether acetate was placed under a nitrogen atmosphere. The temperature was kept at 80°C, and 10.57 g (0.0476 mol) of 5-oxo-4-oxatricyclo[4.2.1.0 methacrylate was added while stirring. 3,7 ]nonan-2-yl, 2.31g (0.0098mol) of 3-hydroxyadamantan-1-yl methacrylate, 3.37g (0.0122mol) of 1-(adamantan-1-yl)-1-methylpropyl methacrylate, 13.75g (0.0525mol) of 2-isopropyladamantan-2-yl methacrylate, 0.75g of dimethyl-2,2'-azobisisobutyrate [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], and 136.0g of propylene glycol monomethyl ether acetate were added dropwise at a constant rate over 6 hours. After the dropwise addition was completed, stirring of the reaction solution was continued for another 2 hours. After the stirring was completed, 9mg of methoquinone was added, and the internal temperature of the reaction solution was cooled to 23°C over 4 hours. Immediately afterwards, the reaction solution was dropped into a 10-fold amount of a mixture (25°C) of heptane and ethyl acetate (9:1 weight ratio) while stirring. The resulting precipitate was filtered and dried under reduced pressure to obtain 23.2 g of the desired resin A-1. The recovered resin was analyzed by GPC and found to have a weight average molecular weight (Mw) of 10100 and a molecular weight distribution (Mw / Mn) of 1.8.

[0113] Resin A-1 has polymerized units represented by the following formula. [ka]

[0114] Example 2 (Preparation of Resin A-2) In a round-bottom flask equipped with a reflux condenser, a stirrer, and a three-way cock, 34.0 g of cyclohexanone was placed in a nitrogen atmosphere, and the temperature was kept at 80°C. 11.06 g (0.0448 mol) of 6-cyano-5-oxo-4-oxatricyclo[4.2.1.0]methacrylate was added with stirring. 3,7]nonan-2-yl, 15.86g (0.0605mol) of 2-isopropyladamantan-2-yl methacrylate, 3.08g (0.0157mol) of 1-isopropylcyclopentan-1-yl methacrylate, 0.57g of dimethyl-2,2'-azobisisobutyrate [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], and 136.0g of cyclohexanone were added dropwise at a constant rate over 6 hours. After the dropwise addition, the reaction solution was stirred for another 2 hours. After the stirring was completed, the internal temperature of the reaction solution was cooled to 23°C over 10 minutes. Immediately after that, 21mg of hydroquinone was added and the mixture was stored at 23°C for 1 day until purification. After storage, the reaction solution was added dropwise to a 10-fold amount of a mixture (25°C) of heptane and ethyl acetate 9:1 (weight ratio) with stirring. The resulting precipitate was filtered and dried under reduced pressure to obtain 19.5 g of the desired resin A-2. The recovered resin was analyzed by GPC and found to have a weight average molecular weight (Mw) of 10,200 and a molecular weight distribution (Mw / Mn) of 1.8.

[0115] Resin A-2 has polymerized units represented by the following formula. [ka]

[0116] Example 3 (Preparation of Resin A-3) In a round-bottom flask equipped with a reflux condenser, a stirrer, and a three-way cock, 34.0 g of propylene glycol monomethyl ether acetate was placed under a nitrogen atmosphere. The temperature was kept at 80°C, and 8.76 g (0.0395 mol) of 5-oxo-4-oxatricyclo[4.2.1.0 methacrylate was added while stirring. 3,7]nonan-2-yl, 4.40g (0.0259mol) of 2-oxotetrahydrofuran-3-yl methacrylate, 8.26g (0.0299mol) of 1-(adamantan-1-yl)-1-methylpropyl methacrylate, 8.58g (0.0408mol) of 1-(cyclohexan-1-yl)-1-methylethyl methacrylate, 0.90g of dimethyl-2,2'-azobisisobutyrate [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], and 136.0g of propylene glycol monomethyl ether acetate were added dropwise at a constant rate over 6 hours. After the dropwise addition, the reaction solution was stirred for another 2 hours. After stirring, 6 mg of 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl free radical was added, and the internal temperature of the reaction solution was cooled to 23°C over 4 hours, and then the solution was stored at 23°C for one day until purification. After storage, the reaction solution was dropped into a 10-fold amount of a mixture (25°C) of heptane and ethyl acetate at a ratio of 9:1 (by weight) while stirring. The resulting precipitate was filtered and dried under reduced pressure to obtain 24.7 g of the desired resin A-3. GPC analysis of the recovered resin showed that Mw (weight average molecular weight) was 14,800 and the molecular weight distribution (Mw / Mn) was 2.0.

[0117] Resin A-3 has polymerized units represented by the following formula. [ka]

[0118] Comparative Example 1 (Preparation of Resin B-1) The procedure of Example 1 was repeated except that methoquinone was not added after the stirring was completed, and 23.4 g of the desired resin B-1 was obtained. The recovered resin was analyzed by GPC and found to have a weight average molecular weight (Mw) of 10,200 and a molecular weight distribution (Mw / Mn) of 1.9.

[0119] Comparative Example 2 (Preparation of Resin B-2) The procedure of Example 2 was repeated except that hydroquinone was not added after cooling the reaction solution, and 19.6 g of the desired resin B-2 was obtained. The recovered resin was analyzed by GPC and found to have a weight average molecular weight (Mw) of 10,100 and a molecular weight distribution (Mw / Mn) of 1.8.

[0120] Comparative Example 3 (Preparation of Resin B-3) The procedure of Example 3 was repeated except that 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl free radical was not added after the stirring was completed, and 24.6 g of the desired resin B-3 was obtained. The recovered resin was analyzed by GPC and found to have a weight average molecular weight (Mw) of 15100 and a molecular weight distribution (Mw / Mn) of 2.0.

[0121] [Turbidity evaluation] Resins A-1 to 3 and B-1 to 3 were dissolved in propylene glycol monomethyl ether acetate so that the solid content concentration was 5% by weight to prepare a resin solution. The polystyrene equivalent turbidity of the resin solution was measured using a turbidity meter (model number: NDH-300A, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the Ministry of Health, Labor and Welfare Notification No. 261 of 2003, Japan Water Works Association, "Testing Method for Drinking Water." The specific procedure is as follows.

[0122] The turbidity of the turbidity standard solution (polystyrene) 100 degrees II manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. was measured using NDH-300A, and the turbidity was 36.62. From this value, it can be understood that when the measured value using NDH-300A is 1.00, the polystyrene equivalent turbidity is 2.731. In other words, the polystyrene equivalent turbidity "Y" can be derived from the following formula. In the formula, "X" is the measured value. Y=2.731X

[0123] The polystyrene equivalent turbidity of the resin solution was calculated according to the above formula. [Table 1]

[0124] As can be seen from the evaluation results, it was revealed that the resins of the present invention (resins A-1 to A-3) have low polystyrene-equivalent turbidity. On the other hand, it was revealed that resins B-1 to B-3 have high polystyrene-equivalent turbidity and are unsuitable for photoresist applications. From this, it is believed that the resins of the present invention can form fine patterns with high accuracy.

[0125] As a summary of the above, the configuration of the present invention and its variations are described below. [1] A photoresist resin made of an acrylic resin, which, when dissolved in propylene glycol monomethyl ether acetate so that the resin solids concentration is 5% by weight, has a polystyrene-equivalent turbidity of 30 or less, 20 or less, 10 or less, 5 or less, or 3 or less, as measured using the method described in the "Drinking Water Testing Method" of the Japan Water Works Association (Ministry of Health, Labour and Welfare Notification No. 261 of 2003). [2] Formulae (a1) to (a4) [wherein R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. R 2 ~R 4 are the same or different and each represents an alkyl group having 1 to 6 carbon atoms which may have a substituent. 2 and R 3 may be bonded to each other to form a ring. 5 , R 6 R is the same or different and represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent. 7 -COOR c R c represents a tertiary hydrocarbon group which may have a substituent, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group. n represents an integer of 1 to 3. R a is Z 1 and are the same or different and each represents an oxo group, an alkyl group, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, or a carboxy group which may be protected by a protecting group. p represents an integer of 0 to 3. Ring Z 1represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms.]. The photoresist resin according to [1], comprising at least one polymerized unit selected from the group consisting of polymerized units represented by the following formulas: [3] The photoresist resin according to [2], wherein the content of at least one type of polymerization unit selected from the group consisting of polymerization units represented by formulas (a1) to (a4) is 1 to 99 mol %, or 5 to 95 mol %, based on all monomer units constituting the resin. [4] Formulae (b1) to (b5) [wherein R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group; X represents a non-bond, a methylene group, an ethylene group, an oxygen atom, or a sulfur atom; Y represents a methylene group or a carbonyl group; and Z represents a divalent organic group. V 1 ~V 3 are the same or different and are -CH 2 -, [-C(=O)-], or [-C(=O)-O-]. However, V 1 ~V 3 At least one of the groups is [-C(=O)-O-]. 8 ~R 14 are the same or different and represent a hydrogen atom, a fluorine atom, an alkyl group which may have a fluorine atom, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group. [5] The photoresist resin according to [4], wherein the content of at least one type of polymerization unit selected from the group consisting of polymerization units represented by formulas (b1) to (b5) is 1 to 99 mol %, or 5 to 95 mol %, based on all monomer units constituting the resin. [6] Furthermore, the compound represented by the formula (c1) [wherein R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom; A represents a single bond or a linking group] brepresents a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group. q represents an integer of 1 to 5. Ring Z 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms.]. The photoresist resin according to any one of [2] to [5], comprising a polymerization unit represented by the following formula: [7] The photoresist resin according to [6], wherein the content of the polymerized units represented by formula (c1) is 1 to 99 mol %, or 5 to 95 mol %, based on all monomer units constituting the resin. [8] The photoresist resin according to any one of [1] to [7], which has a weight average molecular weight (Mw) of 1,000 to 50,000, or 3,000 to 20,000. [9] The photoresist resin according to any one of [1] to [8], having a molecular weight distribution (ratio of weight average molecular weight to number average molecular weight: Mw / Mn) of 3.5 or less, 1.1 to 3.0, or 1.2 to 2.5.

[10] The photoresist resin according to any one of [1] to [9], which has an acid value of 0.10 mmol / g or less, 0.05 mmol / g or less, or 0.03 mmol / g or less.

[11] A method for producing a photoresist resin according to any one of [1] to

[10] , comprising: a step of polymerizing the monomer by dropping a monomer or a solution containing a monomer in the presence of a polymerization initiator; and a step of adding a polymerization inhibitor in an amount of 10 ppm or more, 50 to 2000 ppm, 100 to 1000 ppm, or 200 to 500 ppm relative to the resin solid content contained in the reaction solution after the polymerization step.

[12] The method for producing a photoresist resin according to

[11] , wherein the polymerization inhibitor is at least one selected from the group consisting of hydroquinones, phenols, benzoquinones, and N-oxyl compounds.

[13] A photoresist resin composition comprising at least the photoresist resin according to any one of [1] to

[12] and a radiation-sensitive acid generator.

[14] A method for forming a pattern, comprising at least the steps of applying the photoresist resin composition according to

[13] above to a substrate to form a coating film, exposing the coating film to light, and then dissolving the coating film in an alkali. [Industrial Applicability]

[0126] The resin of the present invention exhibits high resist performance because the content of components hardly soluble in a resist solvent is reduced. Also, the composition of the present invention contains a resin having a reduced content of components hardly soluble in a resist solvent, so it exhibits high resist performance and, by using this, a fine pattern can be formed with high accuracy.

Claims

1. A photoresist resin made of an acrylic resin, When the resin is dissolved in propylene glycol monomethyl ether acetate so that the resin solids concentration is 5% by weight, the polystyrene equivalent turbidity measured using the method described in the "Testing Method for Drinking Water" of the Japan Water Works Association (Ministry of Health, Labor and Welfare Notification No. 261 of 2003) is 30 or less; The following formula (a1) [In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. R 2 represents a methyl group. R 3 represents an ethyl group. R a are substituents bonded to ring Z 1 and may be the same or different and represent an oxo group, an alkyl group, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, or a carboxy group which may be protected by a protecting group. p represents an integer of 0 to 3. Ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms.] Polymer units represented by the following formula (a1'): [In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. R 2 and R 3 are the same or different and represent an alkyl group having 1 to 6 carbon atoms which may have a substituent. R 2 and R 3 may be bonded to each other to form a ring. R a is a substituent bonded to ring Z 1 and is the same or different and represents an oxo group, an alkyl group, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, or a carboxy group which may be protected by a protecting group. p represents an integer of 0 to 3. Ring Z 1 represents a cyclohexane ring.] and a polymerization unit represented by the following formula (a2): [In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, and A represents a single bond or a linking group. R 4 represents an isopropyl group. R a represents a substituent bonded to ring Z 1 and may be the same or different and represents an oxo group, an alkyl group, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, or a carboxy group which may be protected by a protecting group. p represents an integer of 0 to 3. Ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms.] A photoresist resin comprising at least one polymerized unit selected from the group consisting of polymerized units represented by the following formula:

2. The following formulas (b1) to (b5) 【Chemistry 2】 [In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom, A represents a single bond or a linking group, X represents a non-bond, a methylene group, an ethylene group, an oxygen atom, or a sulfur atom, Y represents a methylene group or a carbonyl group, and Z represents a divalent organic group. V １ ~V ３ are the same or different and each represents -CH ２ -, [-C(=O)-], or [-C(=O)-O-]. However, V １ ~V ３ At least one of the groups is [-C(=O)-O-]. ８ ~R １４ are the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group which may have a fluorine atom, a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group.

2. The photoresist resin according to claim 1, comprising at least one polymerized unit selected from the group consisting of polymerized units represented by the following formula:

3. Furthermore, the following formula (c1) 【Chemistry 3】 [In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may have a halogen atom. A represents a single bond or a linking group. R ｂ represents a hydroxy group which may be protected by a protecting group, a hydroxyalkyl group which may be protected by a protecting group, a carboxy group which may be protected by a protecting group, or a cyano group. q represents an integer of 1 to 5. Ring Z ２ represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms.

3. The photoresist resin according to claim 1, comprising a polymerized unit represented by the following formula (excluding those corresponding to the polymerized units represented by the formula (a1) and the formula (a1'):

4. 4. The method for producing a photoresist resin according to claim 1, comprising: a step of polymerizing the monomer by dropping a monomer or a solution containing a monomer in the presence of a polymerization initiator; and a step of adding 10 ppm or more of a polymerization inhibitor relative to a resin solid content contained in the reaction solution after the polymerization step.

5. 5. The method for producing a photoresist resin according to claim 4, wherein the polymerization inhibitor is at least one selected from the group consisting of hydroquinones, phenols, benzoquinones, and N-oxyl compounds.

6. A photoresist resin composition comprising at least the photoresist resin according to any one of claims 1 to 3 and a radiation-sensitive acid generator.

7. A pattern forming method comprising at least the steps of applying the photoresist resin composition according to claim 6 to a substrate to form a coating film, exposing the coating film to light, and then dissolving the coating film in an alkali.

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