Polymer production method

Abstract

[Problem] To provide a polymer production method by which low-molecular-weight impurities can sufficiently be removed without using a large amount of solvent during purification, which provides good polymer yield, and in which properties of a polymer obtained by purification are excellent in workability. [Solution] A polymer production method according to the present invention is characterized by including a preparation step in which a polymer that includes at least a structural unit having a structure including a phenolic hydroxyl group and a structural unit having a structure including an alicyclic group is prepared, and in which the polymer has a lipophilicity parameter of not less than 0.65 to less than 1.00, the lipophilicity parameter being defined by the following formula: the lipophilicity parameter = (total mass of alicyclic groups) / (total mass of phenol groups + total mass of alicyclic groups), and a purification step in which a solution containing the polymer is brought into contact with a nonpolar poor solvent to separate the polymer, in which a good solvent, the nonpolar poor solvent, and a highly polar solvent having no hydroxyl group are used, in which the good solvent contains a solvent of the polymer solution, and in which the mass ratio of the nonpolar poor solvent to the good solvent is 5.0 or more and the mass ratio of the highly polar solvent having no hydroxyl group to the nonpolar poor solvent is 0.06 or more.

Description

Polymer manufacturing method

[0001] This invention relates to a method for producing polymers.

[0002] Photolithography has been conventionally used in semiconductor device manufacturing processes for microfabrication. For example, a thin film of a photolithography composition, such as a photoresist or anti-reflective film, is first formed on a semiconductor substrate such as a silicon wafer. Next, the substrate is etched using an active light such as ultraviolet light, developed by irradiating it through a mask pattern on which the semiconductor device pattern is drawn, and the resulting photoresist pattern is used as a protective film to form fine irregularities on the substrate surface corresponding to the pattern. In order to form such fine patterns, a resist composition with good lithographic properties is required, and in order to improve the lithographic properties of the resist composition, high purity of the resist polymer is required.

[0003] Patent Document 1 discloses a method for producing a polymer containing a structural unit having a phenolic hydroxyl group and a structural unit having an alicyclic group, through a polymerization step and a purification step (paragraphs

[0165] ,

[0188] , etc.).

[0004] Japanese Patent Publication No. 2010-139822

[0005] In the method reported in Patent Document 1, a polar solvent, an alcohol / water mixture, is used as a poor solvent during the purification process. On the other hand, purification using a hydrocarbon-based nonpolar poor solvent is also conceivable, but in order to recover polymers with a high proportion of alicyclic structural units in high yield, a large amount of nonpolar poor solvent is required relative to the amount of good solvent in which the polymer was dissolved before the purification process. In contrast, increasing the amount of nonpolar poor solvent used not only reduces the efficiency of removing polar impurities, but also reduces manufacturing efficiency such as kettle efficiency due to the use of a large amount of solvent. Furthermore, the present inventors have found that in conventional purification processes using poor solvents and good solvents, the separated polymer becomes viscous or hard solid, resulting in poor workability.

[0006] Therefore, there is a need for a polymer manufacturing method that can sufficiently remove low-molecular-weight impurities without using large amounts of solvent during purification, and that yields good polymers. Furthermore, there is a need for a method to produce polymers for resists that have excellent workability properties after purification and are efficient for implementation on a commercial production scale.

[0007] Therefore, an object of the present invention is to provide a method for producing a polymer comprising structural units having a phenolic hydroxyl group and structural units having an alicyclic group, wherein the proportion of structural units having an alicyclic group is large (i.e., the polymer has high lipophilicity), in which low molecular weight impurities can be sufficiently removed without using a large amount of solvent during purification, and the polymer yield is good. Another object of the present invention is to provide an efficient method for implementation on a commercial production scale.

[0008] As a result of diligent research, the present inventors have found that the above problem can be solved by purifying a polymer containing at least one structural unit having a phenolic hydroxyl group and one structural unit having an alicyclic group, wherein the ratio of structural units having an alicyclic group in the polymer is within a specific numerical range, using a predetermined amount of a specific solvent.

[0009] In other words, the present invention provides the following: [1] A method for producing a polymer, comprising: a preparation step of preparing a polymer comprising a structural unit having a structure containing at least a phenolic hydroxyl group and a structural unit having a structure containing an alicyclic group, wherein the polymer has a lipophilicity parameter defined by the following formula: lipophilicity parameter = (total mass of alicyclic groups) / (total mass of phenolic groups + total mass of alicyclic groups) which is 0.65 or more and less than 1.00; and a purification step of contacting a solution containing the polymer with a nonpolar poor solvent to separate the polymer, wherein the purification step uses a good solvent, the nonpolar poor solvent, and a highly polar solvent that does not have hydroxyl groups, wherein the good solvent contains the solvent of the polymer solution, the mass ratio of the nonpolar poor solvent to the good solvent is 5.0 or more, and the mass ratio of the highly polar solvent that does not have hydroxyl groups to the nonpolar poor solvent is 0.06 or more. [2] The method for producing an organic product according to [1], wherein the highly polar solvent that does not have a hydroxyl group comprises at least one selected from the group consisting of acetonitrile, dimethylformamide, dimethyl sulfoxide, and methylpyrrolidone. [3] The method for producing an organic product according to [1] or [2], wherein the highly polar solvent that does not have a hydroxyl group comprises acetonitrile. [4] The method for producing an organic product according to any one of [1] to [3], wherein the non-polar poor solvent comprises a hydrocarbon compound. [5] The method for producing an organic product according to [4], wherein the hydrocarbon compound comprises an aliphatic hydrocarbon compound having 5 to 16 carbon atoms or an alicyclic hydrocarbon compound having 5 to 10 carbon atoms. [6] The method for producing an organic product according to any one of [1] to [5], wherein the good solvent comprises at least one compound selected from the group consisting of ketones, esters, and ethers. [7] The method for producing an organic product according to [6], wherein the ketones comprise an aliphatic ketone. [8] The manufacturing method according to any one of [1] to [7], wherein the highly polar solvent that does not have a hydroxyl group is acetonitrile, the good solvent is at least one of methyl ethyl ketone, acetone, and ethyl acetate, and the nonpolar poor solvent is n-hexane. [9] The manufacturing method according to any one of [1] to [8], wherein the lipophilicity parameter is 0.65 or more and 0.90 or less.

[10] The production method according to any one of [1] to [9], wherein a mass ratio of the highly polar solvent having no hydroxyl group to the non-polar poor solvent is 0.07 or more and 0.33 or less.

[11] The production method according to any one of [1] to

[10] , wherein a mass ratio of the non-polar poor solvent to the good solvent is 5.0 or more and 50.0 or less.

[12] The structural unit having a structure containing a phenolic hydroxyl group is at least represented by the following general formula (1-0): . [In the general formula (1-0), R １１ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. R １２ is a single bond or a divalent linking group optionally having a hetero atom. n is an integer of 1 to 3. ] The production method according to any one of [1] to

[11] , comprising one type represented by the formula.

[13] The structural unit having a structure containing an alicyclic group is at least represented by the following general formula (2-0): [In the general formula (2-0), R ２１ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. R ２２ represents a single bond or a divalent hydrocarbon group having 1 to 30 carbon atoms optionally intervened by a hetero atom, wherein part or all of hydrogen atoms in the hydrocarbon group may be substituted with a group containing a hetero atom. R ２３ represents a divalent hydrocarbon group having 1 to 30 carbon atoms optionally intervened by a hetero atom, wherein part or all of hydrogen atoms in the hydrocarbon group may be substituted with a group containing a hetero atom. m is an integer of 0 to 2. R ２４ is an acid dissociable group represented by the following general formula (2-1). ] [In the general formula (2-1), R ２４１ represents a carbon atom. R ２４２ is R ２４１ a group that together with forms an alicyclic hydrocarbon group or a fused ring of an alicyclic hydrocarbon group and an aromatic hydrocarbon group. * means a bonding hand to the oxygen atom in formula (2-0). R ２４３ is an optionally substituted alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group, or a group represented by the following general formula (2-1-1). In general formula (2-1-1), R ２４３１ , R ２４３２ and R ２４３３ Each of these is independently a hydrogen atom or a saturated aliphatic hydrocarbon group. ２４３１ , R ２４３２ and R ２４３３ Two or more of these may be bonded to each other to form a ring structure. * is R in formula (2-1) ２４１ A manufacturing method according to any one of [1] to

[12] , which includes one type represented by ] which means a coupling with ].

[0010] According to the present invention, a method for producing polymers is provided that can sufficiently remove low-molecular-weight impurities without using large amounts of solvent during purification, and that yields a good polymer product. Furthermore, a method for producing polymers is provided in which the polymer obtained after purification has excellent workability.

[0011] The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. It should be understood that the scope of the present invention also includes modifications, improvements, etc., to the embodiments described below, made in accordance with the ordinary knowledge of those skilled in the art, without departing from the spirit of the invention.

[0012] [Method for Producing Polymers] The present invention provides a method for producing polymers, comprising the steps of: preparing a polymer comprising a structural unit having a structure containing at least a phenolic hydroxyl group and a structural unit having a structure containing an alicyclic group, wherein the polymer has a lipid solubility parameter defined by the following formula: lipid solubility parameter = (total mass of alicyclic groups) / (total mass of phenolic groups + total mass of alicyclic groups) which is 0.65 or more and less than 1.00; and a purification step of contacting a solution containing the polymer with a nonpolar poor solvent to separate the polymer, wherein the purification step uses a good solvent, the nonpolar poor solvent, and a highly polar solvent that does not contain hydroxyl groups, wherein the good solvent contains the solvent of the polymer solution, the mass ratio of the nonpolar poor solvent to the good solvent is 5.0 or more, and the mass ratio of the highly polar solvent that does not contain hydroxyl groups to the nonpolar poor solvent is 0.06 or more. The steps of the present invention provide a method for producing polymers, and will be described below.

[0013] [Preparation Step] This step is for preparing the polymer. The method for preparing the polymer used in the manufacturing method of the present invention is not particularly limited, and the polymer may be prepared by manufacturing it using the steps described later, or it may be prepared by receiving a polymer that has already been manufactured.

[0014] [Polymers] The polymers obtained by the production method of the present invention include structural units having a structure containing at least a phenolic hydroxyl group and structural units having a structure containing an alicyclic group. The following describes each structural unit that constitutes the polymer.

[0015] (Structural units having a structure containing a phenolic hydroxyl group) The structural units having a structure containing a phenolic hydroxyl group are, for example, structural units represented by the following general formula (1-0): [In general formula (1-0), R １１ R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkyl halogen having 1 to 5 carbon atoms. １２ R is a divalent linking group which may have a single bond or a heteroatom. n is an integer from 1 to 3. In formula (1-0), R １１ The group is a hydrogen atom, a C1-C5 alkyl group, or a C1-C5 halogenated alkyl group. Due to their industrial availability, a hydrogen atom or a methyl group is more preferred, and a hydrogen atom is even more preferred.

[0016] In the above formula (1-0), R １２ R is a divalent linking group that may have a heteroatom, or a single bond. １２ Preferred divalent linking groups containing heteroatoms include *-O-, *-C(=O)-O-, *-C(=O)-, *-O-C(=O)-O-, *-C(=O)-NH-, *-NH-, *-NH-C(=NH)- (H may be substituted with substituents such as alkyl groups or acyl groups), *-S-, *-S(=O) ２ -, *-S (=O) ２ -O-, general formula *-Y ２１ -O-Y ２２ -, *-Y ２１ -O-, *-Y ２１-C(=O)-O-, *-C(=O)-O-Y ２１ -, *- [Y ２１ -C (=O) -O] ｍ” -Y ２２ -, *-Y ２１ -OC(=O)-Y ２２ - or * - Y ２１ -S (=O) ２ -O-Y ２２ - is represented by the base [wherein Y ２１ and Y ２２ Each of these is a divalent hydrocarbon group which may independently have substituents, O is an oxygen atom, and m'' is an integer from 0 to 3. * represents a bond to the main chain. Examples include: *-C(=O)-NH-, *-C(=O)-NH-C(=O)-, *-NH-, *-NH-C(=NH)-, where H is substituted with substituents such as alkyl groups and acyl groups. The substituent (alkyl group, acyl group, etc.) preferably has 1 to 10 carbon atoms, more preferably 1 to 8, and particularly preferably 1 to 5 carbon atoms. General formula *-Y ２１ -O-Y ２２ -, *-Y ２１ -O-, *-Y ２１ -C(=O)-O-, *-C(=O)-O-Y ２１ -, *- [Y ２１ -C (=O) -O] ｍ” -Y ２２ -, *-Y ２１ -OC(=O)-Y ２２ - or * - Y ２１ -S (=O) ２ -O-Y ２２ - Middle, Y ２１ and Y ２２ Each of these is independently a divalent hydrocarbon group which may have substituents. The divalent hydrocarbon group is R in formula (2-0) described later. ２３ The same groups mentioned in the explanation of divalent hydrocarbon groups in Y are examples. ２１ As such, linear aliphatic hydrocarbon groups are preferred, linear alkylene groups are more preferred, linear alkylene groups having 1 to 5 carbon atoms are even more preferred, and methylene groups or ethylene groups are particularly preferred. ２２The group is preferably a linear or branched aliphatic hydrocarbon group, more preferably a methylene group, an ethylene group, or an alkylmethylene group. The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group. Formula *-[Y ２１ -C (=O) -O] ｍ” -Y ２２ In the base represented by -, m'' is an integer from 0 to 3, preferably from 0 to 2, more preferably 0 or 1, and particularly preferably 1. That is, the formula * - [Y ２１ -C (=O) -O] ｍ” -Y ２２ As a base represented by -, see formula * -Y ２１ -C(=O)-O-Y ２２ Groups represented by - are particularly preferred. Among them, the group represented by formula *-(CH ２ ) ａ’ -C(=O)-O-(CH ２ ) ｂ’ A base represented by - is preferred. In the formula, a' is an integer from 1 to 10, preferably an integer from 1 to 8, more preferably an integer from 1 to 5, even more preferably 1 or 2, and most preferably 1. b' is an integer from 1 to 10, preferably an integer from 1 to 8, more preferably an integer from 1 to 5, even more preferably 1 or 2, and most preferably 1.

[0017] R １２ The preferred elements are single bonds, ester bonds [*-C(=O)-O-], ether bonds (*-O-), linear or branched alkylene groups, or combinations thereof, with single bonds and ester bonds being more preferred, and single bonds being even more preferred.

[0018] In the present invention, polymerization can be carried out using monomers that have a structure containing a phenolic hydroxyl group, or monomers in which the phenolic hydroxyl group is protected by a protecting group, as monomers that give structural units having a structure containing a phenolic hydroxyl group. Specifically, as an example, a compound represented by the following general formula (1), or a monomer having a structure in which the phenolic hydroxyl group of the compound represented by the following general formula (1) is protected by an acetal group represented by the following general formula (1-1) can be cited. [In general formula (1), R １１ R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkyl halogen having 1 to 5 carbon atoms. １２ R is a divalent linking group which may have a single bond or a heteroatom. n is an integer from 1 to 3. In general formula (1-1), R １３ and R １４ Each of these is independently either a hydrogen atom or an alkyl group. １５ R is a hydrocarbon group that may have a heteroatom interposed therein. １５ R １３ or R １４ It may bond with any of the following to form a ring. * indicates a bond with the oxygen atom in formula (1).

[0019] R in general formula (1) １１ , R １２ And n are the same as those in equation (1-0).

[0020] The monomer having the structure containing the phenolic hydroxyl group may be used alone or in combination of two or more. The monomer is preferably a compound represented by general formula (1) because it offers excellent workability and facilitates the more stable synthesis of the polymer in the present invention.

[0021] (Structural units having a structure containing an alicyclic group) The polymer obtained by the manufacturing method of the present invention has a structural unit having a structure containing an alicyclic group as one of its structural units. An example of a structural unit having a structure containing an alicyclic group is a structural unit having an acid-dissociable group.

[0022] ((Structural Unit Having an Acid-Dissociable Group)) The term "acid-dissociable group" refers to a group in which at least a part of bonds in the structure of the acid-dissociable group can be cleaved by the action of an acid. A structural unit having an acid-dissociable group in a polymer changes the solubility of the polymer in a photolithography developer by causing the acid-dissociable group to dissociate under the action of an acid and generating a highly polar carboxy group. Conventionally known structural units having the acid-dissociable group can be widely used. Among them, the following general formula (2-0) is preferred because properties (sensitivity, shape, etc.) in lithography using EUV (extreme ultraviolet) or EB (electron beam) can be easily improved: [In general formula (2-0), R ２１ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. R ２２ represents a single bond or a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a heteroatom intervening therein, and some or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. R ２３ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a heteroatom intervening therein, and some or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. m is an integer of 0 to 2. R ２４ is an acid-dissociable group represented by the following general formula (2-1).] [In general formula (2-1), R ２４１ represents a carbon atom. R ２４２ is, together with R ２４１ , a group that forms an alicyclic hydrocarbon group or a condensed ring of an alicyclic hydrocarbon group and an aromatic hydrocarbon group. * means a bond to the oxygen atom in formula (2-0). R ２４３ is an optionally substituted alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group, or a group represented by the following general formula (2-1-1). In general formula (2-1-1), R ２４３１ , R ２４３２ and R ２４３３ are each independently a hydrogen atom or a saturated aliphatic hydrocarbon group. R ２４３１ , R ２４３２ and R ２４３３two or more of these may be bonded to each other to form a cyclic structure. * represents a bond to R in formula (2-1) ２４１ A compound represented by the above formula is preferred.

[0023] In formula (2-0), R ２１ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. For the alkyl group having 1 to 5 carbon atoms for R ２１ , a linear or branched alkyl group having 1 to 5 carbon atoms is preferred, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. The halogenated alkyl group having 1 to 5 carbon atoms for R ２１ is a group obtained by substituting part or all of hydrogen atoms of the above alkyl group having 1 to 5 carbon atoms with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferred. As R ２１ , a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms is preferred; in view of industrial availability, a hydrogen atom or a methyl group is more preferred, and a methyl group is even more preferred.

[0024] In formula (2-0), R ２２ represents a single bond or a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a heteroatom interposed therebetween, and part or all of hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. For R ２２ , examples of the divalent hydrocarbon group and the group containing a heteroatom that substitutes for part or all of hydrogen atoms in the hydrocarbon group include the same groups as those for R ２３ described later.

[0025] In formula (2-0), R ２３ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a heteroatom interposed therebetween, and part or all of hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. R ２３The divalent hydrocarbon group in this compound may be a linear hydrocarbon group, a cyclic hydrocarbon group, or a combination thereof. Examples of linear hydrocarbon groups include straight alkylene groups and branched alkylene groups. Examples of cyclic hydrocarbon groups include alicyclic groups such as cyclopentane, cyclohexane, norbornane, isobornane, adamantane, and tricyclodecane; aromatic ring groups such as benzene, naphthalene, fluorene, anthracene, phenanthrene, pyrene, and biphenyl, or fused ring groups thereof. Substituents that the hydrocarbon group may have include alkyl groups, cycloalkyl groups, alkoxy groups, acetyl groups, hydroxyl groups, cyano groups, and halogen atoms. Furthermore, some of the carbon atoms in the hydrocarbon group may be replaced by heteroatoms or groups containing heteroatoms, which may result in the formation of ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, heterocycles, etc.

[0026] In the above formula (2-0), m is an integer between 0 and 2, preferably 0 or 1, and more preferably 0.

[0027] In the above formula (2-0), R ２４ R is an acid-dissociable group. ２４ Suitable examples of acid-dissociating groups in this context include those represented by the general formula (2-1).

[0028] In the above formula (2-1), R ２４１ R represents a carbon atom. ２４２ R ２４１ It is a group that forms an alicyclic hydrocarbon group or a fused ring of an alicyclic hydrocarbon group and an aromatic hydrocarbon group. ２４２ R ２４１The alicyclic hydrocarbon group formed together may be either a monocyclic or polycyclic group. A preferred monocyclic alicyclic hydrocarbon group is a monocycloalkane with one hydrogen atom removed. The monocycloalkane is preferably one having 3 to 6 carbon atoms, specifically cyclopentane, cyclohexane, etc. A preferred polycyclic aliphatic hydrocarbon group is a polycycloalkane with one hydrogen atom removed, and the polycycloalkane is preferably one having 7 to 12 carbon atoms, specifically adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, etc.

[0029] R ２４２ R ２４１ In the fused ring formed by the alicyclic hydrocarbon group and the aromatic hydrocarbon group, the alicyclic hydrocarbon group portion may be monocyclic or polycyclic, and the aromatic hydrocarbon group portion may be monocyclic or polycyclic. Specifically, the aromatic hydrocarbon group portion in the fused ring includes aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which some of the carbon atoms constituting the aromatic hydrocarbon ring are substituted with heteroatoms. Examples of heteroatoms in aromatic heterocycles include oxygen atoms, sulfur atoms, and nitrogen atoms. Specific examples of aromatic heterocycles include pyridine rings, thiophene rings, and furan rings.

[0030] In the above formula (2-1), R ２４２ R ２４１ The alicyclic hydrocarbon group formed together with the aromatic hydrocarbon group, or the fused ring of the alicyclic hydrocarbon group and the aromatic hydrocarbon group, may have substituents. Examples of such substituents include methyl, ethyl, propyl, hydroxy, hydroxyalkyl, carboxy, halogen, alkoxy, acyl, alkyloxycarbonyl, and alkylcarbonyloxy groups.

[0031] In the above formula (2-1), R ２４３ This is a C1-C10 alkyl group or aromatic hydrocarbon group which may have substituents, or a group represented by the general formula (2-1-1).

[0032] R ２４３In this context, examples of alkyl groups having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, 1,1-diethylpropyl group, 2,2-dimethylbutyl group, and among these, methyl group, ethyl group, n-butyl group, isopropyl group, and tert-butyl group are preferred, and methyl group, ethyl group, or isopropyl group are more preferred.

[0033] R ２４３ Examples of substituents that the C1-C10 alkyl group may have include a hydroxyl group, a carboxyl group, a halogen atom, an alkoxy group, and an alkyloxycarbonyl group.

[0034] Regarding aromatic hydrocarbon groups that may have substituents: R ２４３ The aromatic hydrocarbon group in this formula is a hydrocarbon group having at least one aromatic ring. This aromatic ring is not particularly limited as long as it is a cyclic conjugated system having 4n+2 π electrons, and may be monocyclic or polycyclic. The number of carbon atoms in the aromatic ring is preferably 5 to 30, more preferably 5 to 20, even more preferably 6 to 15, and particularly preferably 6 to 12. Specific examples of aromatic rings include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocycles in which some of the carbon atoms constituting the aromatic hydrocarbon ring are substituted with heteroatoms. Examples of heteroatoms in aromatic heterocycles include oxygen atoms, sulfur atoms, and nitrogen atoms. Specific examples of aromatic heterocycles include pyridine rings, thiophene rings, and furan rings. ２４３Specific examples of aromatic hydrocarbon groups in this context include: a group obtained by removing one hydrogen atom from the aromatic hydrocarbon ring or aromatic heterocycle (aryl group or heteroaryl group); a group obtained by removing one hydrogen atom from an aromatic compound containing two or more aromatic rings (e.g., biphenyl, fluorene, etc.); and a group in which one of the hydrogen atoms of the aromatic hydrocarbon ring or aromatic heterocycle is substituted with an alkylene group (e.g., arylalkyl groups such as benzyl group, phenethyl group, 1-naphthylmethyl group, 2-naphthylmethyl group, 1-naphthylethyl group, 2-naphthylethyl group, etc.). The number of carbon atoms in the alkylene group bonded to the aromatic hydrocarbon ring or aromatic heterocycle is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

[0035] R ２４３ Examples of substituents that the aromatic hydrocarbon group in the compound may have include hydroxyl groups, carboxyl groups, halogen atoms, alkoxy groups, alkyloxycarbonyl groups, and the like.

[0036] In the above formula (2-1-1), R ２４３１ , R ２４３２ and R ２４３３ Each of these is independently a hydrogen atom or a saturated aliphatic hydrocarbon group. ２４３１ , R ２４３２ and R ２４３３ Examples of saturated aliphatic hydrocarbon groups in this context include linear saturated hydrocarbon groups, alicyclic saturated hydrocarbon groups, or combinations thereof.

[0037] R ２４３１ , R ２４３２ and R ２４３３ The number of carbon atoms in the chain-like saturated hydrocarbon group is preferably 1 to 10, more preferably 1 to 5. Examples of such chain-like saturated hydrocarbon groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and decyl groups.

[0038] R ２４３１ , R ２４３２ and R ２４３３The number of carbon atoms in the alicyclic saturated hydrocarbon group in is preferably 3 to 20, and examples of such alicyclic saturated hydrocarbon groups include monocyclic groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, and cyclododecyl group; and polycyclic groups such as bicyclo[2.2.2]octanyl group, tricyclo[5.2.1.02,6]decanyl group, tricyclo[3.3.1.13,7]decanyl group, tetracyclo[6.2.1.13,6.02,7]dodecanyl group, and adamantyl group. In the above formula (2-1-1), R ２４３１ , R ２４３２ and R ２４３３ Two or more of these may be bonded to each other to form a ring structure. ２４３１ , R ２４３２ and R ２４３３ Groups containing a carbon-carbon double bond formed by two or more of these groups bonding to each other to form a cyclic structure include, for example, cyclopentenyl group, cyclohexenyl group, methylcyclopentenyl group, methylcyclohexenyl group, cyclopentylideneethenyl group, and cyclohexyllideneethenyl group. Among these, cyclopentenyl group, cyclohexenyl group, and cyclopentylideneethenyl group are preferred from the viewpoint of ease of synthesis of the monomer of general formula (2).

[0039] R ２４３１ , R ２４３２ and R ２４３３ In particular, from the viewpoint of ease of synthesis of the monomer of general formula (2), a hydrogen atom and a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms are preferred, and among these, a hydrogen atom, a methyl group, and an ethyl group are more preferred, with a hydrogen atom being especially preferred.

[0040] Among the acid-dissociating groups represented by the general formula (2-1), R ２４３ Acid-dissociable groups, which are aromatic hydrocarbon groups or groups represented by the general formula (2-1-1), are groups that can dissociate at relatively low energy (sometimes referred to as easily decomposable acid-dissociable groups in this specification) and are suitable for improving the sensitivity of resists. The method of the present invention is suitable for polymerizing polymers containing these easily decomposable acid-dissociable groups.

[0041] The following are specific examples of acid-dissociable groups represented by general formula (2-1). * indicates the bond with the oxygen atom in formula (2-0).

[0042] In the present invention, polymerization can be carried out using monomers having a structure containing an alicyclic group as monomers that provide structural units having a structure containing an alicyclic group. For example, a compound represented by the following general formula (2) can be cited. [R in general formula (2)] ２１ ~R ２４ And m are the same as those in equation (2-0).

[0043] The monomer having the structure containing the alicyclic group may be used alone or in combination of two or more. The monomer is preferably a compound represented by general formula (2) because it offers excellent workability and facilitates the more stable synthesis of the polymer in the present invention.

[0044] Specific examples of monomers of the above general formula (2) include monomers having a structure in which an acid-dissociable group, as exemplified in [Chemical Formula 10] to [Chemical Formula 16], is bonded to an ester bond of acrylic acid or methacrylic acid.

[0045] (Other structural units) The polymer obtained by the manufacturing method of the present invention includes at least structural units having a structure containing a phenolic hydroxyl group and structural units having a structure containing an alicyclic group, and may also include other structural units. When the polymer is used for resist applications, it may include various structural units that provide the necessary performance as a resist. For example, examples of the other structural units include structural units having a photoacid generating group, structural units having a lactone structure or a sultone structure, and structural units having a hydroxyl group or a carboxyl group.

[0046] (Structural units having photoacid-generating groups) Photoacid-generating groups generate acid when irradiated with high-energy rays such as ultraviolet rays, far-ultraviolet rays, electron beams, EUV, X-rays, gamma rays, and synchrotron radiation. When a polymer compound containing this structure is used as the base resin of a resist composition, it is possible to appropriately control the movement and diffusion of the generated acid. Monomers that give structural units having photoacid-generating groups can be widely used from conventional sources, but among them, the following general formula (3): [In general formula (3), R ３１ R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkyl halogen having 1 to 5 carbon atoms. ３２ k is an aromatic hydrocarbon group which may have a single bond or substituents. k is 0 or 1. ３３ R represents a hydrocarbon group having 1 to 30 carbon atoms, which may have single bonds or substituents, and some of the carbon atoms in the hydrocarbon group may be replaced by heteroatoms or groups containing heteroatoms. ３４ R represents a hydrocarbon group having 1 to 15 carbon atoms, and some or all of the hydrogen atoms in the hydrocarbon group may be replaced by fluorine atoms. ３５ , R ３６ and R ３７ Each of these independently represents a hydrocarbon group having 1 to 20 carbon atoms, which may have substituents, and some of the carbon atoms in the hydrocarbon group may be replaced by heteroatoms or groups containing heteroatoms. Also, R ３５ , R ３６ and R ３７ Two or more of these may bond with each other to form a ring with the sulfur atom in formula (3). A monomer represented by ] is preferred.

[0047] In the above formula (3), R ３１ R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkyl halogen having 1 to 5 carbon atoms. ３１ The C1-C5 alkyl group in is preferably a linear or branched alkyl group having C1-C5, specifically including methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, and neopentyl groups. ３１The C1-C5 halogenated alkyl group in this expression is a group in which some or all of the hydrogen atoms of the C1-C5 alkyl group are substituted with halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., with fluorine atoms being particularly preferred. ３１ Preferably, the group is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms. Due to their ease of industrial availability, a hydrogen atom or a methyl group is more preferred, and a methyl group is even more preferred.

[0048] In the above general formula (3), R ３２ R is an aromatic hydrocarbon group which may have a single bond or substituents. Examples of such aromatic hydrocarbon groups include groups obtained by removing two hydrogen atoms from an aromatic ring such as benzene, naphthalene, anthracene, pyrene, and biphenyl, and is preferably a phenylene group. Examples of substituents include alkyl groups, cycloalkyl groups, alkoxy groups, acetyl groups, hydroxyl groups, cyano groups, and halogen atoms, and is preferably unsubstituted. R in the above general formula (3) ３３This represents a hydrocarbon group having 1 to 30 carbon atoms, which may have single bonds or substituents, and some of the carbon atoms in the hydrocarbon group may be replaced by heteroatoms or groups containing heteroatoms. The hydrocarbon group may be a linear hydrocarbon group, a cyclic hydrocarbon group, or a group combining these. Examples of linear hydrocarbon groups include straight alkylene groups and branched alkylene groups. Examples of cyclic hydrocarbon groups include alicyclic groups such as cyclopentane, cyclohexane, norbornane, adamantane, and tricyclodecane; aromatic groups such as benzene, naphthalene, anthracene, pyrene, and biphenyl, or fused ring groups thereof. Examples of substituents that the hydrocarbon group may have include alkyl groups, cycloalkyl groups, alkoxy groups, acetyl groups, hydroxyl groups, cyano groups, and halogen atoms. Among these, fluorine atoms and iodine atoms exhibit high absorbance at 13.5 nm EUV, making them effective for increasing the sensitivity of EUV lithography. Furthermore, some of the carbon atoms in the hydrocarbon group may be replaced by heteroatoms or groups containing heteroatoms, and as a result, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, etc. R in the above general formula (3) ３４ This represents a hydrocarbon group having 1 to 15 carbon atoms, and some or all of the hydrogen atoms in the hydrocarbon group may be replaced with fluorine atoms. The hydrocarbon group is a chain hydrocarbon group, a cyclic hydrocarbon group, or a combination thereof, preferably a chain saturated hydrocarbon group or a cyclic saturated hydrocarbon group, more preferably a chain saturated hydrocarbon group, and even more preferably a chain saturated hydrocarbon group in which some or all of the hydrogen atoms are replaced with fluorine.

[0049] Preferred anion structures for the monomer sulfonium salt represented by the general formula (3) above include, but are not limited to, those listed below.

[0050] In the above general formula (3), R ３５ , R ３６ and R ３７Each of these independently represents a hydrocarbon group having 1 to 20 carbon atoms, which may have substituents, and some of the carbon atoms in the hydrocarbon group may be replaced by a heteroatom or a group containing a heteroatom. Examples of the hydrocarbon group include aromatic hydrocarbon groups such as phenyl, naphthyl, anthracenyl, and biphenyl groups; alkyl groups such as methyl, ethyl, propyl, isopropyl, and tert-butyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl, norbornyl, tricyclo[5.2.1.02,6]decanyl, and adamantyl groups, or combinations thereof. ３５ , R ３６ and R ３７ Any two or more of these may bond with each other to form a ring together with the sulfur atom in formula (3). ３５ , R ３６ , and R ３７ The sulfonium cation containing the hydrocarbon group preferably contains an aromatic hydrocarbon group. Substituents that the hydrocarbon group may have include hydroxyl groups, cyano groups, halogen atoms, etc., and preferably hydroxyl groups or fluorine atoms. In addition, some of the carbon atoms in the hydrocarbon group may be replaced with heteroatoms or groups containing heteroatoms, which may form carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, carbamate bonds, lactone rings, sultone rings, carboxylic acid anhydrides, haloalkyl groups, etc.

[0051] Specific structures of the sulfonium cation represented by the general formula (3) above are shown below. However, the present invention is not limited to these.

[0052] Specific structures of the monomer represented by the general formula (3) of the present invention include any combination of anion and cation of the structures exemplified above.

[0053] Here, we describe a method for synthesizing salts that can be used as raw materials for the monomer represented by the general formula (3) above. The following sulfonium cations are used as examples below, but the present invention is not limited to this method. (In the formula, M represents a cation. R ４１ , R ４２ , R ４３ , R ４４ R indicates a monovalent organic group. ３１ , R ３２ ,k,R ３３ , R ３４ , R ３５ , R ３６ , R ３７ The same applies as above. X － (This indicates a halide ion or methyl sulfate ion.)

[0054] First, a sulfonate represented by formula (20) is synthesized with reference to Japanese Patent Publication No. 2010-215608. Next, the cation of the obtained sulfonate is exchanged for an ammonium cation by ion exchange to obtain an ammonium sulfonate salt represented by formula (21). At this time, the ion exchange reaction can be carried out using an organic solvent such as dichloromethane, ethyl acetate, methyl isobutyl ketone, methanol, ethanol, or acetonitrile alone, or in combination with water. For example, a mixture with an aqueous solution of benzyltrimethylammonium chloride can be used.

[0055] Next, the obtained ammonium sulfonate salt is reacted with an acylating agent to synthesize the acylated ammonium sulfonate salt represented by formula (22) above. This reaction can be easily carried out by known methods. For example, the ammonium sulfonate salt represented by formula (21) above, an acylating agent, and a base such as triethylamine, pyridine, or 4-dimethylaminopyridine are added sequentially or simultaneously in a solvent-free environment or in a solvent such as methylene chloride, toluene, hexane, diethyl ether, tetrahydrofuran, or acetonitrile, and the reaction is carried out by cooling or heating as necessary.

[0056] Furthermore, the sulfonium salt represented by formula (23) is synthesized from the ammonium acylated sulfonate salt represented by formula (22) obtained above. For example, the reaction can be carried out by mixing with an aqueous solution of triphenylsulfonium chloride, for example, using an organic solvent such as dichloromethane, ethyl acetate, methyl isobutyl ketone, methanol, ethanol, or acetonitrile alone or in combination with water.

[0057] In addition, various monomers used in known polymer resists can be used to adjust substrate adhesion, etching resistance, and solubility in resist solvents and lithography developers.

[0058] Examples of structural units having a hydroxyl group or a carboxyl group include those given by monomers such as 2-hydroxyethyl (meth)acrylate and 3-hydroxy-1-adamantyl methacrylate. Examples of structural units having a lactone structure or a sultone structure include those given by monomers such as γ-butyrolactone-α-(meth)acrylate, norbornane lactone (meth)acrylate, and 2-methacryloyloxyacetoxy-4,5-oxathiatricyclo[4.2.1.03,7]nonane-5,5-dioxide.

[0059] [Polymerization Process] When preparing the polymer used in the present invention, it can be prepared by polymerizing a monomer having a structure containing at least a phenolic hydroxyl group, or a monomer in which the phenolic hydroxyl group is protected by a protecting group, with a monomer having a structure containing an alicyclic group. The mode of the polymerization reaction is not particularly limited, but conventionally known polymerization methods such as radical polymerization, cationic polymerization, and living anionic polymerization can be applied.

[0060] In the radical polymerization method, monomers, radical polymerization initiators, and optionally chain transfer agents are dissolved in a solvent and heated and stirred, preferably under an inert gas atmosphere such as nitrogen. For example, this can be carried out by a so-called batch polymerization method in which all raw materials such as monomers, polymerization initiators, and chain transfer agents are dissolved in a solvent and heated to the polymerization temperature, a method in which monomers are dissolved in a solvent and heated to the polymerization temperature before adding the polymerization initiator, or a so-called dropwise polymerization method in which a solution of monomers and polymerization initiators dissolved in a solvent is added dropwise to a solvent heated to the polymerization temperature. Among these, the dropwise polymerization method is preferred because it offers high reproducibility for each production lot, and can also be carried out by a so-called independent dropwise method in which the monomers and polymerization initiators, which are radical sources, are added dropwise separately. The monomers, polymerization initiators, and chain transfer agents can also be supplied in advance in portions within the polymerization system. In the dropwise polymerization method, the monomer concentration and radical concentration within the polymerization system can be adjusted by changing the composition of the supplied monomer solution and the supply speed of the monomer solution and polymerization initiator, thereby controlling the dispersion and compositional distribution of the resulting polymer.

[0061] Conventional radical polymerization initiators, such as azo polymerization initiators and peroxide polymerization initiators, can be used. Specific examples of azo polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 1,1'-azobis(cyclohexane-1-carbonitride), and 4,4'-azobis(4-cyanovaleric acid). Azo compound polymerization initiators are preferred due to their superior handling safety. Specific examples of peroxide-based polymerization initiators include decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, bis(3,5,5-trimethylhexanoyl) peroxide, succinate peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, and 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate. These polymerization initiators can be used individually or in combination. The amount of polymerization initiator used can be selected according to the target molecular weight, the type of monomer, polymerization initiator, chain transfer agent, solvent, structural unit composition, polymerization temperature, and dropping rate.

[0062] As a chain transfer agent, known chain transfer agents can be used as needed. Among these, thiol compounds are preferred, and a wide range of known thiol compounds can be selected. Specifically, examples include t-dodecyl mercaptan, mercaptoethanol, mercaptoacetic acid, and mercaptopropionic acid. Furthermore, thiol compounds having a structure in which a 2-hydroxy-1,1,1,3,3,3-hexafluoro-2-propyl group is bonded to a saturated aliphatic hydrocarbon are particularly preferred because they have the effect of suppressing roughness and defects in the lithography pattern. The amount of chain transfer agent used can be selected according to the target molecular weight, the type of monomer, polymerization initiator, chain transfer agent and solvent, the structural unit composition, polymerization temperature and dropping rate, etc.

[0063] The solvent used in the polymerization reaction is not particularly limited as long as it can stably dissolve the monomer, polymerization initiator, chain transfer agent, and the resulting polymer. Specific examples of polymerization solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, methyl amyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, and isopropanol; ether alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; esters such as methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate, and methyl propionate; ether esters such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as tetrahydrofuran, 1,4-dioxane, and ethylene glycol dimethyl ether; aromatic hydrocarbons such as toluene and xylene; and N,N-dimethylformamide, acetonitrile, and chloroform.

[0064] The polymerization solvent can be used alone or as a mixture of two or more. Alternatively, a mixture of compounds with high solubility and high boiling points for monomers, polymerization initiators, chain transfer agents, and the resulting polymer may be used, such as 3-methoxy-3-methyl-1-butyl acetate, ethyl 3-ethoxypropionate, γ-butyrolactone, diethylene glycol dimethyl ether, N-methylpyrrolidone, and dimethyl sulfoxide. A particularly excellent embodiment of the present invention involves using a polymerization solvent that is a mixture of a highly polar solvent (e.g., acetonitrile in Synthesis Example 2) that does not contain hydroxyl groups and a good solvent (e.g., methyl ethyl ketone in Synthesis Example 2) in an appropriate ratio. Reducing the amount of good solvent used in the polymerization solvent reduces the amount of non-polar poor solvent used in the subsequent purification step. When polymerizing with a mixed solvent, the solvent mixing ratio should be appropriately set within a range where the monomers, polymer, etc., are sufficiently dissolved.

[0065] There are no particular restrictions on the amount of polymerization solvent used, but if the amount of solvent used is too little, monomers may precipitate or the viscosity may become too high, making it impossible to maintain a uniform polymerization system. If the amount is too much, the monomer conversion rate may be insufficient or the molecular weight of the polymer may not be increased to the desired value. Typically, the amount of solvent is 0.5 to 20 parts by mass, preferably 1 to 10 parts by mass, per 1 part by mass of monomer.

[0066] In the dropwise polymerization method, the amount of solvent initially added to the reaction vessel (hereinafter sometimes referred to as the initial solvent) should be at least the minimum amount required for stirring. However, if it is excessively large, the amount of monomer solution that can be supplied will decrease, potentially reducing production efficiency. Typically, the initial solvent is selected from a range of 1 / 30 or more, preferably 1 / 20 to 1 / 2, and particularly preferably 1 / 10 to 1 / 3, relative to the final charge (i.e., the total amount of the initial solvent, the monomer solution to be added dropwise, and the initiator solution), in terms of volume ratio. It is also possible to pre-mix a portion of the monomer into the initial solvent.

[0067] In dropwise polymerization, if the dropping time is too short, there is a risk of broad dispersion, and if a large amount of solution is added at once, there is a risk of the polymerization solution temperature dropping. Conversely, if the dropping time is too long, there is a risk of the polymer being subjected to excessive heat history, and productivity may decrease. Therefore, the dropping time is usually selected from a range of 0.5 to 24 hours, preferably 1 to 12 hours, and particularly preferably 2 to 8 hours.

[0068] Furthermore, after the dropwise addition is complete, and after the temperature has been raised to the polymerization temperature in the batch heating method, it is preferable to maintain the temperature for a certain period of time or raise the temperature further to allow the remaining unreacted monomers to react. If the maturation time is too long, the production efficiency per unit of time may decrease, and the polymer may be subjected to more heat history than necessary. Therefore, it is usually selected from within 12 hours, preferably within 6 hours, and particularly preferably within 1 to 4 hours.

[0069] The polymerization temperature can be appropriately selected depending on the boiling points of the solvent, monomers, chain transfer agents, and the half-life temperature of the polymerization initiator. Polymerization may not proceed well at low temperatures, and if the temperature is set too high, problems may arise in terms of the stability of the monomers and polymers. Therefore, it is preferable to select a temperature in the range of 40°C to 140°C, more preferably 60°C to 120°C, and even more preferably 70°C to 100°C. The polymerization temperature greatly affects the molecular weight and copolymer composition of the polymer, so it is preferable to control it. On the other hand, polymerization reactions are generally exothermic reactions, and the polymerization temperature tends to rise, making it difficult to control to a constant temperature. For this reason, in the present invention, it is preferable to include at least one compound having a boiling point close to the target polymerization temperature as the polymerization solvent, and to set the polymerization temperature to be above the initial boiling point of the compound at the polymerization pressure. According to this method, the rise in polymerization temperature can be suppressed by the latent heat of vaporization of the polymerization solvent.

[0070] The polymerization pressure is not particularly limited and may be atmospheric pressure, pressurized pressure, or reduced pressure, but is usually atmospheric pressure. In the case of radical polymerization, nitrogen gas is generated when radicals are generated from the initiator, and in the case of azo polymers, nitrogen gas is generated. Therefore, in order to suppress fluctuations in polymerization pressure, it is preferable to carry out the polymerization in an open system at or near atmospheric pressure.

[0071] [Other steps in the preparation process] When preparing the polymer used in the present invention, if a monomer in which the phenolic hydroxyl group is protected by a protecting group is used, a step is performed to remove the protecting group and expose the phenolic hydroxyl group (also referred to as the "deprotection step"). The deprotection reaction can be carried out by known methods. For example, if the protecting group is an acetyl group, a deprotection reaction using a base catalyst is possible, while if the protecting group is an acetal group, a deprotection reaction using an acid catalyst is possible. However, if the polymer (A) has a structure that can be decomposed by an acid or base, such as a repeating unit having an acid-dissociable group or a repeating unit having a lactone structure, attention must be paid to the strength and type of acid or base used and the reaction temperature.

[0072] (Lipidophilicity parameter) In the present invention, the "lipidophilicity parameter" is a parameter defined by the following formula: Lipidophilicity parameter = (total mass of alicyclic groups) / (total mass of phenolic groups + total mass of alicyclic groups) This parameter represents the weighted average ratio of alicyclic groups to the total number of phenolic and alicyclic groups. That is, the higher the molar ratio of alicyclic groups in the polymer of the present invention, and when the number of alicyclic groups and phenolic groups are equimolar, the higher the mass of alicyclic groups, the larger this parameter becomes. Therefore, polymers with a large value of this parameter tend to have high lipophilicity.

[0073] (Total mass of phenol groups) In the "lipidophilic parameters" above, "mass of phenol groups" refers to the sum of the masses of the phenolic hydroxyl group and the aromatic ring group bonded to the phenolic hydroxyl group. For example, the mass of the phenol group in formula (1-0) above can be calculated as follows: (molar mass of benzene ring 78.12 g / mol) - (n+1) × (molar mass of hydrogen atom 1.01 g / mol) + n × (molar mass of OH group 17.01 g / mol) = (77.11 + 16.00 n) g / mol

[0074] (Total mass of alicyclic groups) In the above "lipidophilicity parameters," "mass of alicyclic groups" refers to the mass of alicyclic groups. For example, the mass of alicyclic groups in formula (2-0) is (R ２４ (Molar mass of) = (R ２４ It can be calculated as ) g / mol.

[0075] The purification process of the present invention can be suitably used when the lipophilicity parameter of the polymer of the present invention is 0.65 or more and less than 1.00. More specifically, the lipophilicity parameter of the polymer of the present invention is preferably 0.65 or more and 0.95 or less, more preferably 0.65 or more and 0.90 or less, and even more preferably 0.65 or more and 0.85 or less. Since the production method of the present invention obtains a highly lipophilic polymer in high yield while using a small amount of poor solvent, it can suitably solve problems in the production of polymers whose lipophilicity parameter is within the above numerical range (such as the efficiency of removal of low molecular weight impurities and the properties of the separated polymer).

[0076] [Purification Process] The manufacturing method of the present invention includes a step of purifying a polymer having a specific structure using a predetermined amount of a specific solvent. This is effective in removing impurities such as solvent, unreacted monomers, oligomers, and reaction by-products from the polymer obtained by the manufacturing method of the present invention, or in obtaining a polymer with a desired degree of dispersion. At the same time, with conventional purification solvents, it is difficult to recover the polymer in high yield because not only the above-mentioned impurities but also the target polymer is eluted. On the other hand, increasing the amount of non-polar poor solvent used not only reduces the efficiency of removing polar impurities but also reduces manufacturing efficiency such as kettle efficiency due to the use of a large amount of solvent. Furthermore, the inventors have found that in conventional purification processes using poor and good solvents, the precipitated polymer becomes viscous or hard solid, resulting in poor workability. In response to these problems, the purification process performed in the manufacturing method of the present invention can recover the polymer in high yield without increasing the amount of poor solvent used, thus providing an efficient method even for implementation on a commercial production scale.

[0077] This purification process involves contacting a solution containing the polymer with a highly polar solvent that does not contain hydroxyl groups and a poor solvent to separate the two phases, partitioning impurities into the poor solvent phase, and separating the polymer into a phase different from the poor solvent layer (for example, the lower phase) (hereinafter referred to as two-phase separation). The phase different from the poor solvent layer is preferably a liquid phase. In this process, by adding a highly polar solvent that does not contain hydroxyl groups, the polymer can be recovered in high yield. The reason for this is not entirely clear, but it is presumed to be as follows: In conventional purification, the polymer dissolves into the poor solvent phase, reducing the yield of the polymer. However, in this invention, a predetermined amount of a non-polar poor solvent and a good solvent are used, along with a predetermined amount of a highly polar solvent that does not contain hydroxyl groups. As a result, more of the polymer is separated into a phase different from the poor solvent layer, which suppresses the dissolution of the polymer into the poor solvent phase, and consequently, the polymer can be recovered in high yield. Furthermore, if the phase different from the poor solvent phase is a liquid phase, the poor solvent phase and the highly polar solvent that does not have hydroxyl groups will separate into liquid and liquid phases, and the polymer can be separated in good condition. However, the above reason is merely speculation, and the present invention is not bound by this logic.

[0078] (Good Solvent) The good solvent used in this purification step is characterized by containing the solvent of the solution containing the polymer. The good solvent is the same as that given as an example of the polymerization solvent, but preferably contains at least one compound selected from the group consisting of ketones, esters, and ethers. Examples of ketones include aliphatic ketones, aromatic ketones, and cyclic ketones, but more preferably the ketones contain aliphatic ketones. The good solvent is even more preferably at least one of methyl ethyl ketone, acetone, and ethyl acetate, and particularly preferably methyl ethyl ketone. When using the good solvent in this purification step, for example, the solvent to be used as the good solvent may be mixed with the polymer to prepare a polymer solution, or the reaction solution containing the polymer obtained in the polymerization step (hereinafter also referred to as the "polymerization solution") may be used as is and brought into contact with the non-polar poor solvent. Alternatively, the same or a different good solvent as the solvent of the polymerization solution may be added to the polymerization solution.

[0079] (Non-polar poor solvent) The non-polar poor solvent used in this purification step can be any solvent that separates the polymer of the present invention from a good solvent without particular limitations. The non-polar poor solvent is characterized in that its mass ratio to the good solvent is 5.0 or higher. Furthermore, there is no particular upper limit to the mass ratio, but it can be set appropriately considering the reduction in production efficiency such as the efficiency of removal of polar impurities and the efficiency of the vessel, as described above. More specifically, the mass ratio of the non-polar poor solvent to the good solvent is preferably 5.0 or more and 50.0 or less, more preferably 5.0 or more and 40.0 or less, and even more preferably 5.0 or more and 30.0 or less. When the mass ratio of the non-polar poor solvent to the good solvent is within the above numerical range, the yield of the target polymer is increased, and the properties of the polymer separated from the good solvent are also favorable.

[0080] Examples of the nonpolar poor solvent include hydrocarbon compounds such as aliphatic hydrocarbon compounds and aromatic hydrocarbon compounds (e.g., toluene), but preferably aliphatic hydrocarbon compounds having 5 to 16 carbon atoms or alicyclic hydrocarbon compounds having 5 to 10 carbon atoms, more preferably aliphatic hydrocarbon compounds having 5 to 16 carbon atoms, and even more preferably n-hexane.

[0081] (Highly polar solvent without hydroxyl groups) The highly polar solvent without hydroxyl groups used in this purification process can be any solvent that is highly polar and does not have hydroxyl groups, without any particular restrictions. The highly polar solvent without hydroxyl groups is characterized in that its mass ratio to the non-polar poor solvent is 0.06 or higher. There is no particular upper limit to the mass ratio, but it can be set appropriately considering the efficiency of impurity removal, etc. More specifically, the mass ratio of the highly polar solvent without hydroxyl groups to the non-polar poor solvent is preferably 0.07 or more and 0.33 or less, more preferably 0.07 or more and 0.25 or less, and even more preferably 0.07 or more and 0.20 or less. When the mass ratio of the highly polar solvent without hydroxyl groups to the non-polar poor solvent is within the above numerical range, the yield of the target polymer is increased, and the properties of the polymer separated from the good solvent are also favorable.

[0082] Examples of highly polar solvents that do not have hydroxyl groups include acetonitrile, dimethylformamide, dimethyl sulfoxide, and methylpyrrolidone. Preferably, the solvent contains at least one selected from the group consisting of acetonitrile, dimethylformamide, dimethyl sulfoxide, and methylpyrrolidone, more preferably it contains acetonitrile, and even more preferably it contains acetonitrile.

[0083] Furthermore, the method of the present invention can be suitably used when the polymer to be purified in the present invention does not dissolve in the hydroxyl-free highly polar solvent, that is, when the hydroxyl-free highly polar solvent is a poor solvent for the polymer to be purified in the present invention.

[0084] In the aforementioned two-phase separation, the poor solvent phase can be removed by methods such as suction or decantation, and the separated polymer solution can be recovered. In addition, in the liquid-liquid separation, the amount of liquid removed may be adjusted as appropriate, taking into consideration the operability of the manufacturing equipment. In liquid-liquid separation type purification, unwanted impurities are removed into the poor solvent phase, which becomes the supernatant. In this case, in order to improve the reproducibility of polymer purity between batches in repeated manufacturing, it is also possible to intentionally leave only a portion of the supernatant and control the quantity in the process.

[0085] The temperature during the purification process greatly affects the molecular weight, dispersibility, and removal rate of impurities such as residual monomers and initiator residues of the polymer, so it is preferable to control it. If the purification temperature is too low, the solubility of impurities in the extraction solvent and washing solvent may be insufficient, and conversely, if it is too high, the polymer may elute into the purification solvent, disrupting the compositional balance in the low molecular weight region of the polymer and potentially reducing the yield. For this reason, purification is preferably carried out in the range of 0 to 80°C, more preferably in the range of 0 to 60°C, and even more preferably in the range of 0 to 40°C.

[0086] [Further Purification Step] In the manufacturing method of the present invention, after performing the above purification step once, the above purification step may be performed one or more times thereafter (hereinafter, the further purification steps performed one or more times will also be referred to as the "further purification step"). The further purification step may be performed by two-phase separation using the same combination of solvent type and amount as in the first purification step, or it may be performed using a different combination of solvent type or amount than in the first purification step.

[0087] In the two-phase separation in the further purification step, the separated polymer can be recovered by liquid-liquid separation of the separated polymer and the poor solvent phase by methods such as suction or decantation, similar to the first purification step. Similarly, in the liquid-liquid separation in the further two-phase separation, the amount of liquid removed may be appropriately adjusted to improve operability.

[0088] In the configuration in which the above-mentioned further purification step is performed, there are no particular restrictions on the amounts of the good solvent, nonpolar poor solvent, and highly polar solvent without hydroxyl groups used in the further purification step, as long as they are carried out in the predetermined mass ratio described above, but preferably they can be carried out as follows.

[0089] That is, the mass ratio of the good solvent in the further purification step to the good solvent in the first purification step is preferably 0.10 or more and 1.00 or less, more preferably 0.10 or more and 0.80 or less, even more preferably 0.10 or more and 0.60 or less, and even more preferably 0.10 or more and 0.40 or less. The mass ratio of the highly polar solvent without hydroxyl groups in the further purification step to the highly polar solvent without hydroxyl groups in the first purification step is preferably 0.10 or more and 1.00 or less, more preferably 0.20 or more and 0.80 or less, and even more preferably 0.30 or more and 0.70 or less.

[0090] Alternatively, in the further purification step, the mass ratio of the nonpolar poor solvent to the good solvent is preferably 10.0 or more, more preferably 10.0 to 50.0, and even more preferably 15.0 to 40.0.

[0091] In other words, from the viewpoint of manufacturing efficiency, the amount of good solvent in the further purification step may be reduced compared to the amount of good solvent in the first purification step, and accordingly, the mass ratio of the non-polar poor solvent to the good solvent may be kept within the above numerical range. Similarly, if the amount of good solvent in the further purification step is reduced, the amount of highly polar solvent without hydroxyl groups in the further purification step may be reduced compared to the amount of highly polar solvent without hydroxyl groups in the first purification step, as this reduces the risk of a decrease in polymer yield.

[0092] [Other steps] The polymer after the purification step may then be subjected to further purification steps using a different type or amount of solvent than specified in the present invention, filtration, or solvent replacement, as needed.

[0093] [Resin Composition for Resists] The polymer obtained by the manufacturing method of the present invention is useful as a base polymer for a resin composition for resists. In addition to the polymer, the resin composition for resists includes an acid generator, an acid diffusion inhibitor, a solvent that uniformly dissolves these, and these can be those that have been known in the past. Furthermore, the resin composition for resists may optionally contain compounds that are commonly used as additives for resists, such as organic carboxylic acids and phosphorus oxoacids for the purpose of preventing degradation of the sensitivity of the acid generator and improving the shape and stability of the resist pattern, additional resins for improving the performance of the resist film, surfactants for improving coatability, dissolution inhibitors, plasticizers, stabilizers, colorants, anti-halation agents, dyes, etc.

[0094] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0095] [NMR Analysis] The NMR conditions used in this example are as follows. [Polymer Composition Ratio] The monomer composition ratio of the polymer synthesized below is: １３ Analysis was performed by 13C-NMR. Instrument: Bruker AV400 Deuterated solvent: Acetone-d6 Relaxation reagent: Chromium(III) acetylacetonate Measurement temperature: 40°C

[0096] (Calculation of Lipid-Soluble Parameters) In this example, the molar ratio of structural units having phenolic hydroxyl groups and structural units having alicyclic groups in the prepared polymer was determined by the above NMR measurement, and the lipid-solubility parameter was calculated as: Lipid-solubility parameter = (Total mass of alicyclic groups) / (Total mass of phenolic groups + Total mass of alicyclic groups).

[0097] [GPC Analysis] The GPC conditions used in this example are as follows. The weight-average molecular weight, molecular weight distribution, and purity of the polymer synthesized below were measured by GPC (gel permeation chromatography) using polystyrene as a standard. The sample used for analysis was prepared to be a tetrahydrofuran solution with a solid content concentration of 2% by mass of the polymer. The sample injection volume into the instrument was 50 μL. Measurement instrument: Tosoh HLC-8220GPC Detector: Differential refractive index (RI) detector Column: Shodex GPC KF804 x 3 (Showa Denko) Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min Temperature: 40°C Calibration curve: Created using a polystyrene standard sample (Tosoh)

[0098] [Evaluation of Low Molecular Weight Impurities] In this example, the GPC chart of the polymer was obtained by the GPC measurement described above, and the purity of the polymer was calculated. Here, for example, "low molecular weight impurities = 0.01%" means that the area of ​​the low molecular weight components on the GPC chart is 0.01% of the area of ​​the polymer on the GPC chart.

[0099] The monomers and solvents used in this example, along with their abbreviations, are shown below. *1 4-HS: 4-hydroxystyrene TBCPMA: 1-(tert-butyl)cyclopentyl methacrylate ECPMA: 1-ethylcyclopentyl methacrylate *2 MEK: methyl ethyl ketone Acetone: acetone AceEt: ethyl acetate Hex: n-hexane AN: acetonitrile MeOH: methanol

[0100] [Synthesis Example 1] In a container, 130 g of 25% by mass 4-HS / MEK solution, 133.4 g of TBCPMA, 21.1 g of dimethyl 2,2-azobisisobutyrate, and 74.8 g of MEK were added and mixed to prepare a monomer solution. 130 g of MEK was placed in a 500 mL four-necked glass reaction vessel equipped with a stirrer, condenser, and thermometer, and the atmosphere was changed to nitrogen, after which the temperature was raised to 79°C. The monomer solution was then added dropwise at a constant rate over 4 hours, and the reaction was continued for a further 2 hours. The temperature during the polymerization reaction was controlled to 78.5–79.5°C, and after the polymerization was completed, the mixture was cooled to room temperature. The weight composition of the solution was (monomer + polymerization initiator + polymer) 38.2% by mass and solvent MEK 61.8% by mass. Analysis of the polymerization reaction solution by GPC revealed a conversion rate of 4-HS = 100%, TBCPMA = 92%, and a weight-average molecular weight of the polymer Mw = 4,530, with Mw / Mn = 1.70. NMR analysis of the resulting polymer showed a 4-HS / TBCPPMA molar composition ratio of 30 / 70 and a lipophilicity parameter value of 0.76. (Calculated using phenol group molecular weight = 93.10 and alicyclic group molecular weight = 125.23.)

[0101] [Example 1] (First Purification) 40 g of the polymerization reaction solution from Synthesis Example 1 was placed in a container with 160 g of n-hexane and 16 g of acetonitrile, stirred, and then allowed to stand to separate into two layers. The polymer was contained in the lower layer. The lower layer solution containing the polymer was separated by decantation. The solvent composition ratio used in the first purification of Example 1 was hexane (non-polar poor solvent) / MEK (good solvent) ratio = 160 / (40 × 61.8%) = 6.5, and acetonitrile (highly polar solvent) / hexane (non-polar poor solvent) = 16 / 160 = 0.10. (Second and Third Purifications) 8 g of acetone, 10 g of acetonitrile, and 160 g of hexane were added to the remaining polymer-containing solution, stirred, and allowed to stand to separate into two layers. The lower layer solution containing the polymer was separated by decantation. The same procedure as the second purification was repeated one more time. Analysis of the purified polymer by GPC revealed low molecular weight impurities = 0.00%, Mw = 5490, and Mw / Mn = 1.48. The yield of the purified polymer was 64%. Analysis of the purified polymer by NMR revealed that the composition ratio (molar ratio) of the polymer was 4-HS:TBCPMA = 35.0:65.0. Table 1 summarizes the mass ratio of nonpolar poor solvent / good solvent and the mass ratio of highly polar solvent without hydroxyl groups / nonpolar poor solvent for all three purification steps.

[0102] [Synthesis Example 2] In a container, 66.0 g of 25% by mass 4-HS / MEK solution, 72.1 g of ECPMA, 12.2 g of dimethyl 2,2-azobisisobutyrate, 3.5 g of MEK, and 37.0 g of acetonitrile were added and mixed to prepare a monomer solution. 38.5 g of MEK and 26.8 g of acetonitrile were charged into a 500 mL four-necked glass reaction vessel equipped with a stirrer, condenser, and thermometer, and the atmosphere was changed to nitrogen, after which the temperature was raised to 79°C. The monomer solution was then added dropwise at a constant rate over 4 hours, and the reaction was continued at 79°C for another 2 hours before being cooled to room temperature. The weight composition of the solution was (monomer + polymerization initiator + polymer) 39.4% by mass, MEK 35.7% by mass, and acetonitrile 24.9% by mass. Analysis of the polymerization solution revealed a 4-HS conversion rate of 100%, an ECPMA conversion rate of 93%, a weight-average molecular weight Mw = 3,790, and a molecular weight distribution Mw / Mn = 1.71. The 4-HS / ECPMA molar composition ratio of the obtained polymer was 27.2 / 72.8, and the lipophilicity parameter value was 0.74. (Calculated using phenol group molecular weight = 93.10 and alicyclic group molecular weight = 97.18)

[0103] [Example 2] (First purification) 80 g of the polymerization reaction solution from Synthesis Example 2 was mixed with 160 g of n-hexane, stirred, and then allowed to stand to separate into two layers. The polymer was contained in the lower layer. The lower layer solution containing the polymer was separated by decantation. At this point, a portion was sampled and the gross yield was calculated to be 75%. Less polymer loss was achieved in the first purification with less poor solvent than in Example 1. The solvent composition ratio for Example 2 in the first purification was hexane / MEK (good solvent) ratio = 160 / (80 × 35.7%) = 5.6, and acetonitrile (highly polar solvent) / hexane (non-polar poor solvent) = (80 × 24.9%) / 160 = 0.125. (Second to fourth purifications) 4 g of acetone, 12 g of acetonitrile, and 120 g of n-hexane were added to the remaining polymer-containing solution, stirred, and allowed to stand to separate into two layers. The lower layer solution containing the polymer was separated by decantation. The same procedure as the second purification was repeated two more times, for a total of four purifications. The obtained polymer was analyzed by GPC and found to contain 0.01% low-molecular-weight impurities, with Mw = 4,570 and Mw / Mn = 1.48. The yield of the purified polymer was 67%. The purified polymer was analyzed by NMR and found that the composition ratio (molar ratio) of the polymer was 4-HS:ECPMA = 30.5:69.5.

[0104] [Example 3] Using 80 g of the polymerization reaction solution obtained in Synthesis Example 2, a total of four purifications were performed under the same conditions as in Example 2, except that the good solvent used in "(purification 2nd to 4th time)" in Example 2 was changed from 4 g of acetone to 8 g of ethyl acetate. When the purified polymer was analyzed by GPC, the low molecular weight impurities were 0.00%, Mw = 4,660, and Mw / Mn = 1.47. The yield of the purified polymer was 64%. This shows that by performing the first purification under predetermined conditions, it is possible to achieve a similar reduction in low molecular weight impurities and polymer recovery in terms of polymer yield even when the solvent type and amount used are changed in the second and subsequent purifications.

[0105] [Example 4] Using 80 g of the polymerization reaction solution obtained in Synthesis Example 2, purification was performed four times using the same amount and type of solvent (acetone, acetonitrile) as in Example 2. At that time, the amount of upper layer liquid removed was adjusted so that the amount of lower layer liquid (including some of the upper layer liquid) remaining after decantation was 80 g each time. When the purified polymer was analyzed by GPC, the low molecular weight impurities were 0.02%, Mw = 4,500, and Mw / Mn = 1.50. The yield of the purified polymer was 71%. From this, it was shown that by performing the purification process under predetermined conditions, even if the amount of liquid removed during the separation process is changed, the reduction of low molecular weight impurities and the recovery of polymer at a similar level in terms of polymer yield can be achieved.

[0106] [Comparative Example 1] (First Purification) 40 g of the polymerization reaction solution obtained in the polymerization reaction of Synthesis Example 1 was added to 160 g of n-hexane and stirred. The polymer precipitated as a hard solid. The polymer was separated by decantation. (Second and Third Purification) 18 g of acetone was added to the remaining polymer and it was redissolved. This was then added to 160 g of n-hexane, stirred, and the precipitated polymer was separated by decantation. This process was repeated twice. Analysis of the purified polymer by GPC showed that low molecular weight impurities = 0.00%, Mw = 5,700, and Mw / Mn = 1.41. The yield of the purified polymer was 58%. In purification without acetonitrile, the polymer precipitates as a hard solid, so it is expected that redissolution in a good solvent will be difficult in commercial production scale manufacturing.

[0107] [Comparative Example 2] (First Purification) 40 g of the polymerization reaction solution obtained in the polymerization reaction of Synthesis Example 1 was added to 160 g of n-hexane and stirred. The polymer precipitated as a hard solid. The polymer was separated by decantation. (Second and Third Purifications) 18 g of acetone and 4 g of methanol were added to the remaining polymer and it was redissolved. This was then added to 160 g of n-hexane and stirred, causing a viscous polymer to precipitate. The polymer was separated by decantation. The same procedure as in the second purification was repeated one more time. Analysis of the purified polymer by GPC showed that low molecular weight impurities = 0.00%, Mw = 5890, and Mw / Mn = 1.39. The yield of the purified polymer was 49%. This purification method resulted in a significantly lower polymer yield compared to Example 1.

[0108] [Comparative Example 3] 40 g of the polymerization reaction solution obtained in Synthesis Example 1 was added to 40 g of methanol and stirred. The solution remained a homogeneous layer, and no polymer precipitated. When another 40 g of methanol was added, the solution became cloudy, but the polymer could not be separated and recovered.

[0109] [Comparative Example 4] (First Purification) 40 g of the polymerization reaction solution obtained in the polymerization reaction of Synthesis Example 1 was added to 80 g of acetonitrile and stirred. The polymer precipitated as a hard solid. The polymer was separated by decantation. (Second and Third Purification) 20 g of acetone was added to the remaining polymer to redissolve it, and this was added to 80 g of acetonitrile and stirred. The precipitated polymer was separated by decantation, and this operation was repeated twice. When the purified polymer was analyzed by GPC, Mw = 5690, Mw / Mn = 1.47, and the yield was 66%, but more than 1% of low molecular weight impurities remained, indicating insufficient purification.

[0110] [Comparative Example 5] Purification was carried out in the same manner as in Example 1, except that acetonitrile used in "(First Purification)" and "(Second and Third Purifications)" of Example 1 was replaced with methanol. More specifically, purification was carried out by the following method. (First Purification) 40 g of the polymerization reaction solution from Synthesis Example 1 was placed in a container containing 160 g of n-hexane and 16 g of methanol, stirred, and then allowed to stand to separate into two layers. The polymer was contained in the lower layer. The lower layer solution containing the polymer was separated by decantation. The solvent composition ratio used in the first purification of Example 1 was hexane (non-polar poor solvent) / MEK (good solvent) ratio = 160 / (40 × 61.8%) = 6.5, and methanol (highly polar solvent) / hexane (non-polar poor solvent) = 16 / 160 = 0.10. (Purification 2nd and 3rd times) To the remaining polymer-containing solution, 8 g of acetone, 10 g of methanol, and 160 g of hexane were added, stirred, and allowed to stand to separate into two layers. The lower layer solution containing the polymer was separated by decantation. The same procedure as in the second purification was repeated one more time. Analysis of the purified polymer by GPC revealed low molecular weight impurities = 0.00%, Mw = 7180, and Mw / Mn = 1.33. The yield of the purified polymer was 23%. The polymer yield was significantly lower compared to Example 1.

[0111] [Comparative Example 6] Purification was carried out in the same manner as in Example 1, except that the amount of acetonitrile in "(First Purification)" was changed from 16 g to 8 g, and the amount of acetonitrile in "(Second and Third Purifications)" was changed from 10 g to 2 g. The polymer precipitated in a viscous state during purification. Analysis of the purified polymer by GPC showed that low molecular weight impurities = 0.00%, Mw = 5640, and Mw / Mn = 1.44. The yield of the purified polymer was 53%. Although the polymer yield was slightly higher than in Comparative Example 1, which did not use acetonitrile, it was lower than the polymer yield in Example 1. The solvent composition ratio of Comparative Example 6 in the first purification was acetonitrile / hexane = 0.05. The hexane / MEK (good solvent) ratio was 160 / (80 × 35.7%) = 5.6.

[0112] [Comparative Example 7] Purification was carried out in the same manner as in Example 1, except that the amount of n-hexane in "(First Purification)" was changed from 160 g to 100 g and the amount of acetonitrile was changed from 16 g to 8 g, and the amount of n-hexane in "(Second and Third Purifications)" was changed from 160 g to 100 g and the amount of acetonitrile was changed from 10 g to 2 g. The polymer precipitated in a viscous state during purification. Analysis of the purified polymer by GPC showed that low molecular weight impurities = 0.00%, Mw = 6130, and Mw / Mn = 1.33. The yield of the purified polymer was 41%. The ratio of hexane, a nonpolar poor solvent, to acetone, a good solvent, was low, and the polymer could not be sufficiently separated, resulting in a lower yield.

[0113] (Synthesis Example 3) The polymerization reaction was carried out in the same manner as in Synthesis Example 2, except that the monomer solution was prepared and the acetonitrile charged in the four-necked flask reaction vessel was replaced with MEK in the same amount, and the polymerization solvent was changed to MEK only. The polymerization reaction solution was analyzed by GPC. The conversion rate was 4-HS = 100%, ECPMA = 95%, the weight-average molecular weight of the polymer Mw = 3,800, and Mw / Mn = 1.70. The 4-HS / ECPMA molar composition ratio of the obtained polymer was 26.8 / 73.2, and the lipophilicity parameter value was 0.74. (Calculated using phenol group molecular weight = 93.10 and alicyclic group molecular weight = 97.18) The weight composition of the solution was (monomer + polymerization initiator + polymer) = 39.4%, with solvent MEK at 60.6%.

[0114] [Comparative Example 8] (First Purification) 100 g of polymerization reaction solution was added to 230 g of n-hexane and stirred. The polymer precipitated as a hard solid. The polymer was separated by decantation. A portion of the polymer was sampled and analyzed by GPC, which showed a yield of 50%. Further purification is necessary to remove low molecular weight impurities, but since it was found that the yield would be low at this point, the experiment was terminated. When the polymerization solvent is only MEK, a good solvent, it is expected that more poor solvent (n-hexane) will be needed to increase the polymer yield. In Comparative Example 7, the solvent composition ratio after the first purification was hexane / MEK (good solvent) ratio = 230 / (100 × 60.4%) = 3.8.

[0115] Table 1 summarizes the experimental conditions and evaluation results for the first purification run in Examples 1-4 and Comparative Examples 1-8. Similarly, Table 2 summarizes the experimental conditions for the second and subsequent purification runs, and Table 3 summarizes the evaluation results after the completion of purification.

[0116]

[0117]

[0118]

[0119] The present invention enables the production of high-purity polymers with good workability in the manufacture of polymers containing structural units having phenolic hydroxyl groups and structural units having alicyclic groups. In all of Examples 1 and 2-4, by performing the purification step using predetermined amounts of a good solvent, a non-polar poor solvent, and a highly polar solvent without hydroxyl groups, it was possible to reduce low-molecular-weight impurities, obtain a separated product with good properties, and recover the polymer in high yield. Example 2, using Synthesis Example 2, is a method of reducing the proportion of good solvent in the polymer solution by using a mixed solvent of a good solvent and a highly polar solvent without hydroxyl groups in an appropriate composition ratio as the polymerization solvent. This has the effect of reducing the amount of non-polar poor solvent used in the second and subsequent purification steps. In Comparative Examples 1, 2 and 6, 7, it is thought that the precipitate obtained in the purification step became viscous because predetermined amounts of the highly polar solvent without hydroxyl groups were not used. Comparative Example 5 was purified in the same manner as in Example 1, except that the highly polar solvent without hydroxyl groups (acetonitrile) used in the first to third purification steps was changed to a highly polar solvent containing hydroxyl groups (methanol). The purification process appeared to be liquid-liquid separation, and the same level of workability as in Example 1 was ensured. However, when an alcohol containing hydroxyl groups was used as the highly polar solvent, the above-mentioned decrease in yield occurred. This is presumably because the phenol of the highly lipophilic polymer interacted with the hydroxyl groups of the alcohol, resulting in a large distribution of the polymer into the non-polar poor solvent phase. In Comparative Example 3, it is thought that the polymer did not precipitate because a non-polar poor solvent was not used. Furthermore, Comparative Example 4 shows that acetonitrile acts as a poor solvent for highly lipophilic polymers. However, acetonitrile also has low dissolving power for low-molecular-weight impurities, and it is thought that it could not suitably separate the polymer from the impurities, resulting in the above-mentioned amount of low-molecular-weight impurities. In Comparative Example 8, the amount of good solvent was so large that the mass ratio of the nonpolar poor solvent to the good solvent (nonpolar poor solvent / good solvent) was less than 5.0. Furthermore, a highly polar solvent without hydroxyl groups was not used, which likely led to the elution of the polymer and the resulting yield.

[0120] The polymer obtained by the present invention can be suitably used as a resist for EUV or EB lithography.

Claims

1. A method for producing a polymer, comprising: a preparation step of preparing a polymer comprising a structural unit having a structure containing at least a phenolic hydroxyl group and a structural unit having a structure containing an alicyclic group, wherein the polymer has a lipophilicity parameter defined by the following formula: lipophilicity parameter = (total mass of alicyclic groups) / (total mass of phenolic groups + total mass of alicyclic groups) which is 0.65 or more and less than 1.00; and a purification step of contacting a solution containing the polymer with a nonpolar poor solvent to separate the polymer, wherein the purification step uses a good solvent, the nonpolar poor solvent, and a highly polar solvent that does not have hydroxyl groups, wherein the good solvent contains the solvent of the polymer solution, the mass ratio of the nonpolar poor solvent to the good solvent is 5.0 or more, and the mass ratio of the highly polar solvent that does not have hydroxyl groups to the nonpolar poor solvent is 0.06 or more.

2. The production method according to claim 1, wherein the highly polar solvent that does not have a hydroxyl group comprises at least one selected from the group consisting of acetonitrile, dimethylformamide, dimethyl sulfoxide, and methylpyrrolidone.

3. The method for producing a product according to claim 1 or 2, wherein the highly polar solvent that does not have a hydroxyl group includes acetonitrile.

4. The manufacturing method according to any one of claims 1 to 3, wherein the nonpolar poor solvent includes a hydrocarbon compound.

5. The manufacturing method according to claim 4, wherein the hydrocarbon compound comprises an aliphatic hydrocarbon compound having 5 to 16 carbon atoms or an alicyclic hydrocarbon compound having 5 to 10 carbon atoms.

6. The manufacturing method according to any one of claims 1 to 5, wherein the good solvent comprises at least one compound selected from the group consisting of ketones, esters, and ethers.

7. The manufacturing method according to claim 6, wherein the ketones include aliphatic ketones.

8. The manufacturing method according to any one of claims 1 to 7, wherein the highly polar solvent that does not have a hydroxyl group is acetonitrile, the good solvent is at least one of methyl ethyl ketone, acetone, and ethyl acetate, and the nonpolar poor solvent is n-hexane.

9. The manufacturing method according to any one of claims 1 to 8, wherein the lipid solubility parameter is 0.65 or more and 0.90 or less.

10. The manufacturing method according to any one of claims 1 to 9, wherein the mass ratio of the highly polar solvent that does not have hydroxyl groups to the non-polar poor solvent is 0.07 or more and 0.33 or less.

11. The manufacturing method according to any one of claims 1 to 10, wherein the mass ratio of the nonpolar poor solvent to the good solvent is 5.0 or more and 50.0 or less.

12. The structural unit having the structure containing the phenolic hydroxyl group is at least the following general formula (1-0): [In general formula (1-0), R １１ R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkyl halogen having 1 to 5 carbon atoms. １２ The manufacturing method according to any one of claims 1 to 11, comprising one represented by ], where is a divalent linking group which may have a single bond or a heteroatom. n is an integer from 1 to 3.

13. The structural unit having a structure containing the alicyclic group is at least represented by the following general formula (2-0): [In general formula (2-0), R ２１ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. R ２２ represents a single bond or a divalent hydrocarbon group having 1 to 30 carbon atoms which may be intervened by a heteroatom, and part or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. R ２３ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may be intervened by a heteroatom, and part or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. m is an integer of 0 to 2. R ２４ is an acid-dissociable group represented by the following general formula (2-1).] [In general formula (2-1), R ２４１ represents a carbon atom. R ２４２ is a group that forms, together with R ２４１ , an alicyclic hydrocarbon group or a fused ring of an alicyclic hydrocarbon group and an aromatic hydrocarbon group. * means a bond to the oxygen atom of formula (2-0). R ２４３ is an optionally substituted alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group, or a group represented by the following general formula (2-1-1). In general formula (2-1-1), R ２４３１ , R ２４３２ and R ２４３３ each independently represent a hydrogen atom or a saturated aliphatic hydrocarbon group. R ２４３１ , R ２４３２ and R ２４３３ two or more of them may be bonded to each other to form a ring structure. * means a bond to R ２４１ of formula (2-1).] The production method according to any one of claims 1 to 12, comprising one type represented by

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