Method for producing polymer

Abstract

[Problem] To provide a method for producing a polymer having a molecular weight Mw of 20,000 or greater while suppressing excessive crosslinking of the polymer. [Solution] A method for producing a polymer according to the present invention is characterized by comprising: a step for supplying, into a system, a raw material containing a monomer including an acrylic monomer, a radical polymerization initiator, and a polyvalent acrylate crosslinking agent and performing a polymerization reaction, the supplying step including a step for adjusting a molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator so as to satisfy being more than 1.0 but not more than 4.6 in a time zone in which the supply amount of the raw material is from 40% to 100% of the total supply amount; and a step for further promoting the polymerization reaction after completion of the supplying step, the promotion step being implemented until the amount of the monomer present in the promotion step becomes at most 25.0 mol% of the amount of the monomer present at the start of the promotion step, and the change of the weight average molecular weight Mw of the polymer after the promotion step from the weight average molecular weight Mw at the end of the promotion step with respect to the weight average molecular weight Mw at the start of the promotion step being less than 5.0%.

Description

Polymer manufacturing method

[0001] This invention relates to a method for producing polymers containing crosslinked structures, particularly polymers for photoresist applications.

[0002] Photoresist-based pattern formation technology is used in various industrial applications. In recent years, its use has increased in processes with resolutions ranging from a few micrometers to tens of micrometers, and in so-called back-end processes in semiconductor manufacturing. Acrylic polymers, whose solubility in alkaline developers changes through photoreaction, are used as the base resin for photoresists. In processes with film thicknesses ranging from a few micrometers to tens of micrometers, it is necessary to use resin solutions with high viscosity from the viewpoint of coatability, and therefore, there is a tendency to increase the weight-average molecular weight of the polymer. In the production of acrylic copolymers, it has been common practice to add diacrylate, a crosslinking agent, to increase the molecular weight. However, when applied to photoresist applications, it is necessary to avoid the excessive crosslinking reaction of a portion of the polymer due to the addition of the crosslinking agent, which can lead to the formation of poorly soluble substances that are insoluble in the solvent. Furthermore, in the production of acrylic base resins used in processes ranging from a few micrometers to tens of micrometers, from the viewpoint of reducing production costs, it is common practice to copolymerize multiple monomers in an organic solvent for resist coating to increase the monomer conversion rate, and then use the resulting polymer solution directly as the material for the resist composition.

[0003] Patent Document 1 discloses the synthesis of an acrylic copolymer for photoresists containing 10 mol% or less of the crosslinking agent diacrylate.

[0004] Japanese Patent Publication No. 2007-327062

[0005] Patent Document 1 discloses a method for producing polymers with a molecular weight of approximately Mw 10,000, but does not disclose a method for obtaining polymers with a molecular weight of Mw 20,000 or more. Therefore, Patent Document 1 does not teach a method for producing a high-viscosity resin obtained from polymers having such molecular weights. Furthermore, the present inventors have newly discovered a problem in which excessive crosslinking occurs in the accelerated polymer when carrying out a step to accelerate the reaction of unreacted monomers and increase the conversion rate (hereinafter also referred to as the "accelerating step") in obtaining polymers having the above molecular weights. Since the manufacturing method disclosed in Patent Document 1 does not include an acceleration step, no specific guidance for solving the problem in such an acceleration step is taught.

[0006] Therefore, the object of the present invention is to provide a method for producing a polymer with a molecular weight Mw of 20,000 or more, in which excessive crosslinking of the polymer is suppressed.

[0007] As a result of diligent research, the present inventors have found that in a method for producing polymers with a molecular weight Mw of 20,000 or more, the above problem can be solved by adjusting the ratio of the amount of crosslinking agent supplied to the amount of radical polymerization initiator consumed during a specific time period of the polymerization reaction to a specific numerical range, and by continuing the acceleration step until the amount of monomer consumed falls within a specific range.

[0008] In other words, the present invention provides the following invention.

[0009] [1] A method for producing a polymer having a weight-average molecular weight Mw of 20,000 or more, comprising the steps of: supplying raw materials containing an acrylic monomer, a radical polymerization initiator, and a polyvalent acrylate crosslinking agent into a system and carrying out a polymerization reaction, wherein in the supply step, during the time period when the supply amount of the raw materials is 40% or more of the total supply amount until it reaches 100%, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 1.0 and less than or equal to 4.6; and after the end of the supply step, a step of further promoting the polymerization reaction, wherein the promotion step is carried out until the amount of monomer present in the promotion step is at least 25.0 mol% or less of the amount of monomer present at the start of the promotion step, and the change in the weight-average molecular weight Mw of the polymer from the weight-average molecular weight Mw at the end of the promotion step to the weight-average molecular weight Mw after the promotion step is less than 5.0% of the weight-average molecular weight Mw at the start of the promotion step. [2] The manufacturing method according to [1], wherein the total amount supplied of the polyvalent acrylate crosslinking agent is 2.0 moles or more and 10.0 moles or less per 100 moles of the total amount supplied of the acrylic monomer. [3] The manufacturing method according to [1] or [2], wherein in the supply step, the conversion rate of the monomer and the polyvalent acrylate crosslinking agent is further adjusted so that the conversion rate of the monomer and the polyvalent acrylate crosslinking agent is 65% or more during the time period when the amount supplied of the raw materials is 40% or more of the total supply. [4] The manufacturing method according to any one of [1] to [3], carried out in the absence of a chain transfer agent. [5] The manufacturing method according to any one of [1] to [4], wherein the conversion rate of the monomer is 70% or more at the end of the supply step and 90% or more at the end of the acceleration step. [6] The manufacturing method according to any one of [1] to [5], wherein during the time period when the amount supplied of the raw materials is 40% to 50% of the total supply, the molar ratio of the amount supplied of the polyvalent acrylate crosslinking agent to the amount consumed of the radical polymerization initiator is greater than 3.0 and 4.6 or less. [7] The manufacturing method according to any one of [1] to [6], wherein, at the point when the supply amount of the raw materials is 100% of the total supply amount, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 1.8 and less than 3.3.[8] The manufacturing method according to any one of [1] to [7], wherein the radical polymerization initiator is added at the start of the acceleration step. [9] The manufacturing method according to any one of [1] to [8], wherein the weight-average molecular weight Mw of the polymer is 50,000 or less.

[10] The manufacturing method according to any one of [1] to [9], wherein the time of the supply step is 3 hours or more.

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

[10] , wherein the time of the acceleration step is 1 hour or more and 6 hours or less.

[12] The manufacturing method according to any one of [1] to

[11] , wherein, before carrying out the polymer manufacturing method, the supply amount of the raw material per unit time and the amount of the radical polymerization initiator used are adjusted by the following preliminary test so that the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 1.8 and less than or equal to 4.6 during the time period when the supply amount of the raw material is 40% or more and 100% of the total supply amount. (Preliminary Test) In the supply process, the amount of the radical polymerization initiator consumed is measured during the time period when the amount of the raw material supplied is between 40% and 100% of the total supply amount. If the molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed is greater than 4.6, the supply time or the amount of the radical polymerization initiator used is set by extending the supply time of the raw material or increasing the amount of the radical polymerization initiator used.

[0010] According to the manufacturing method of the present invention, an acrylic copolymer for photoresists having a molecular weight Mw of 20,000 or more, with excessive crosslinking suppressed, can be obtained. Furthermore, since the manufacturing method of the present invention can produce polymers without using chain transfer agents, it has the advantage of not requiring the use of thiol compounds, which are chain transfer agents that cause odors.

[0011] This figure shows the time change in the weight-average molecular weight of the polymer during the polymerization reaction in Comparative Example 1 and Example 1. This figure shows the time change in the conversion rate of the monomer and crosslinking agent during the polymerization reaction in Comparative Example 1 and Example 1.

[0012] 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.

[0013] [Method for producing polymers] The present invention provides a method for producing polymers, comprising the steps of supplying raw materials containing an acrylic monomer, a radical polymerization initiator, and a polyvalent acrylate crosslinking agent into a system and carrying out a polymerization reaction, wherein in the supply step, during the time period when the supply amount of the raw materials is 40% or more of the total supply amount until it reaches 100%, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 1.0 and less than or equal to 4.6, and further promoting the polymerization reaction after the end of the supply step, wherein the promotion step is carried out until the amount of monomer present in the promotion step is at least 25.0 mol% or less of the amount of monomer present at the start of the promotion step, and the change in the weight-average molecular weight Mw of the polymer from the weight-average molecular weight Mw at the end of the promotion step to the weight-average molecular weight Mw after the promotion step is less than 5.0% of the weight-average molecular weight Mw at the start of the promotion step.

[0014] In other words, in the manufacturing method of the present invention, the molecular weight of the polymer during the polymerization reaction is adjusted by adjusting the stoichiometry of the monomer, crosslinking agent, and polymerization initiator. As a result, even if a step to further accelerate the polymerization reaction is carried out after the polymerization step, excessive crosslinking of the polymer does not occur, and a polymer having a suitable molecular weight can be produced. Moreover, the manufacturing method of the present invention can produce a desired polymer by suppressing the excessive crosslinking mentioned above, even in the absence of a chain transfer agent.

[0015] The reason for this is not clear, but it is speculated as follows: In the manufacturing method of the present invention, by adjusting the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator to be within a predetermined numerical range during the time period when the raw material supply amount is between 40% and 100% of the total, the polyvalent acrylate crosslinking agent is not supplied in excess, and excessive crosslinking of the polymer can be suppressed. Furthermore, even without simply reducing the polyvalent acrylate crosslinking agent, by increasing the consumption amount of the radical polymerization initiator, the number of polymerization initiation sites present in a polymer that has undergone a certain degree of polymerization can be kept within an appropriate number, and as a result, excessive crosslinking of the polymer can also be suppressed. Thus, while in a normal polymerization reaction the molecular weight of the polymer is adjusted by a chain transfer agent, in the present invention the molecular weight of the polymer can be adjusted by adjusting the stoichiometry of the polymerization initiator, etc., as described above, and it is thought that an excessive increase in the molecular weight of the polymer can be suppressed without using a chain transfer agent. However, the above mechanism is merely speculation, and the present invention is not bound by this logic.

[0016] [Polymer] The polymer produced by the present invention is not particularly limited, but preferably has structural units derived from acrylic monomers. Preferably, as an example of the structural units derived from acrylic monomers, it has at least one structural unit (A) having a structure in which a carboxyl group is protected by an acid-dissociative dissolution inhibitory group. An acid-dissociative dissolution inhibitory group is a group that inhibits the dissolution of the polymer in an alkaline developer and dissociates upon the action of an acid, allowing the polymer to dissolve in the alkaline developer. Furthermore, the structural units derived from acrylic monomers may optionally include structural units having a lactone ring structure (B), structural units having a hydroxyl group or a carboxyl group (C), structural units having a structure in which a carboxyl group is protected by a group that inhibits dissolution in an alkaline developer and is stable against the action of an acid (hereinafter sometimes referred to as an "acid-stable dissolution inhibitory group") (D), etc. The structural units derived from acrylic monomers may further include other structural units such as structural units derived from monomers other than acrylics.

[0017] (Structural unit (A) having a structure in which a carboxyl group is protected by an acid-dissociative dissolution inhibitory group) Structural unit (A) having a structure in which a carboxyl group is protected by an acid-dissociative dissolution inhibitory group that dissociates upon the action of an acid is a structural unit having a structure in which a carboxyl group derived from an acrylic monomer is protected by an acid-dissociative dissolution inhibitory group. Preferably, it is a structural unit in which a carboxyl group in a structural unit derived from (meth)acrylic acid, etc., is protected by an acid-dissociative dissolution inhibitory group.

[0018] A structural unit (A) having a structure in which a carboxyl group is protected by an acid-dissociation-inhibiting group is, for example, the structure represented by formula (A). In formula (A), R １１ R represents a hydrocarbon group having 1 to 4 carbon atoms that may be substituted with a hydrogen atom or a fluorine atom. Specific examples include alkyl groups having 1 to 4 carbon atoms such as a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and a trifluoromethyl group. Preferably, it is a hydrogen atom, a methyl group, or a trifluoromethyl group. １２ This represents a divalent hydrocarbon group having 1 to 30 carbon atoms, which may have a single bond or interposed heteroatoms, and some or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. The divalent hydrocarbon group may be a chain hydrocarbon group, a cyclic hydrocarbon group, or a group combining these. Examples of chain 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. 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. 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. １２is preferably a single bond. R １３ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may be intervened by a hetero atom, and part or all of hydrogen atoms in the hydrocarbon group may be substituted with a group containing a hetero atom. R １３ preferred examples are the same as those for R １２ . m is an integer of 0 to 2, preferably 0 or 1, more preferably 0. R １４ represents an acid dissociable dissolution inhibiting group. Examples of the acid dissociable dissolution inhibiting group include structures represented by formula (a1) or (a2). In formula (a1), * represents a bonding site to the oxygen atom of formula (A) as formula (a1), and R １４１ and R １４２ each independently represent a hydrocarbon group having 1 to 4 carbon atoms, and specifically, alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, and i-butyl group can be mentioned. R １４３ represents a hydrocarbon group having 1 to 12 carbon atoms, specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, cyclopentyl group, cyclohexyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 dodecanyl group and other linear, branched or cyclic alkyl groups having 1 to 12 carbon atoms, and aryl groups having 6 to 12 carbon atoms such as phenyl group and naphthyl group. In addition, R １４３ may be bonded to R １４１ or R １４２ to form a ring, specifically a cyclopentane ring, cyclohexane ring, norbornane ring, tricyclo[5.2.1.0 2,6 decane ring, adamantane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane ring and other alicyclic rings having 5 to 12 carbon atoms. In particular, for R １４３ , or R １４３ is R １４１ or R １４２It combines with saturated alicyclic rings, specifically cyclopentane rings, cyclohexane rings, norbornane rings, and tricyclo[5.2.1.0 2,6 ] Decane ring, adamantane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 The presence of dodecane rings, etc., results in a significant difference in solubility in alkaline developer before and after lithography, which is preferable for drawing fine patterns. In formula (a2), * represents the bonding site with the oxygen atom in formula (A) as formula (a2), and R １４４ and R １４５ Each of these independently represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. Specifically, examples include hydrogen atoms, methyl groups, ethyl groups, n-propyl groups, i-propyl groups, n-butyl groups, i-butyl groups, and other alkyl groups having 1 to 4 carbon atoms. １４６ The term represents a hydrocarbon group having 1 to 12 carbon atoms, specifically the methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group, norbornyl group, tricyclo[5.2.1.0 2,6 ] decanyl group, adamantyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 Examples include linear, branched, or cyclic alkyl groups having 1 to 12 carbon atoms, such as a dodecanyl group. １４４ R １４５ or R １４６ It may also bond with R to form a ring, １４４ R １４５ Examples of rings bonded to it include cyclopentane rings, cyclohexane rings, norbornane rings, and tricyclo[5.2.1.0 2,6 ] Decane ring, adamantane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 ] Dodecane rings, etc., and also R １４４ R １４６ Specific examples of rings bonded to these rings include hydrofuran rings and hydropyran rings, respectively.

[0019] The following are specific examples of structural units (A) having a structure in which a carboxyl group is protected by an acid-dissociation-inhibiting group, but these are not limited to the present invention. One type or multiple types of different structures can be selected and used from among these structural units. (In the formula, Rx is H, CH) ３ or CF ３ (This represents...)

[0020] (Structural unit (B) having a lactone ring structure) Structural unit (B) having a lactone ring structure is a structural unit derived from an acrylic monomer and has a lactone ring structure. This lactone ring structure enhances adhesion to substrates and undercoats, and controls solubility in lithography solvents and alkaline developers. A preferred example is the structure represented by formula (B1). In formula (B1), R ２１ R represents a hydrocarbon group having 1 to 4 carbon atoms, which may be substituted with a hydrogen atom or a fluorine atom. ２１ Specific examples and preferred examples are those described above in R １１ It is similar to R. ２２ R represents a divalent hydrocarbon group having 1 to 30 carbon atoms, which may have a single bond or interposed heteroatoms, and some or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. ２２ Specific examples and preferred examples are those described above in R １２ It is similar to R. ２３ R represents a divalent hydrocarbon group having 1 to 30 carbon atoms, which may contain a heteroatom, and some or all of the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. ２３ Specific examples and preferred examples are those described above in R １３ It is similar to the one in [reference]. m' is an integer between 0 and 2, preferably 0 or 1, and more preferably 0. R ２４ represents a lactone structure-containing group represented by formula (b). In formula (b), R ２４１ ~R ２４８ One of the following is R ２４As formula (B1), it represents the single bond that is the bonding site with the oxygen atom, and the remaining, R ２４１ ~R ２４８ R represents a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or an alkoxy group, or R ２４１ ~R ２４８ One of the following is R ２４ It has a bonding site with the oxygen atom of formula (B1) as, and other, R ２４１ ~R ２４８ It represents a hydrocarbon group having 3 to 14 carbon atoms, which may contain an oxygen atom or a sulfur atom, and which is bonded to one or two of the following to form an alicyclic ring having 5 to 15 carbon atoms, and the remaining, R ２４１ ~R ２４８ One or two of these represent single bonds that form the alicyclic ring with 5 to 15 carbon atoms, and the others, R ２４１ ~R ２４８ n represents a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or an alkoxy group. n represents an integer of 0 or 1.

[0021] Specific examples of the above alicyclic rings include cyclopentane rings, cyclohexane rings, norbornane rings, 7-oxa-norbornane rings, 7-thia-norbornane rings, and tetracyclo[4.4.0.1 2,5 .1 7,10 Examples of carbon-1 to carbon-4 hydrocarbon groups include dodecane rings, preferably norbornane rings and 7-oxa-norbornane rings. Specific examples of carbon-1 to carbon-4 alkoxy groups include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, etc. Specific examples of carbon-1 to carbon-4 alkoxy groups include methoxy group, ethoxy group, etc.

[0022] In formula (b), R ２４１ ~R ２４８ One of the following is R ２４ As formula (B1), it represents a single bond having a bonding site with the oxygen atom, and the remaining R ２４１ ~R ２４８ Particularly preferred examples of lactone structures representing a hydrogen atom or a hydrocarbon group or alkoxy group having 1 to 4 carbon atoms include the γ-butyrolactone structure and the δ-valerolactone structure. ２４１ ~R ２４８ One of the following is R２４ It has a bonding site with the oxygen atom of formula (B1) as, and other R ２４１ ~R ２４８ It represents a hydrocarbon group having 3 to 14 carbon atoms that may contain an oxygen atom or a sulfur atom, which is bonded to one or two of the following to form an alicyclic ring having 5 to 15 carbon atoms, and the remaining R ２４１ ~R ２４８ Particularly preferred examples of lactone structures representing a hydrogen atom or a hydrocarbon group or alkoxy group having 1 to 4 carbon atoms include the 1,3-cyclohexanecarbolactone structure, the 2,6-norbornanecarbolactone structure, the 7-oxa-2,6-norbornanecarbolactone structure, and the 4-oxa-tricyclo[5.2.1.0 2,6 One example is the decane-3-one structure.

[0023] The following are specific examples of structural units (B) having a lactone ring structure, but these are not intended to limit the present invention. One type or multiple types of different structures can be selected and used from among these structural units (B). (In the formula, Rx is H, CH) ３ or CF ３ (This represents...)

[0024] (Structural unit (C) having a hydroxyl group or carboxyl group) The structural unit (C) having a hydroxyl group or carboxyl group is a structural unit derived from an acrylic monomer and has a hydroxyl group or carboxyl group. The hydroxyl group or carboxyl group enhances adhesion to the substrate or underfilm, controls solubility in lithography solvents and alkaline developers, and reacts with curing agents to form crosslinked structures. A preferred example of the structural unit (C) having a hydroxyl group is the structure represented by formula (C1). In formula (C1), R ３１represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms which may be substituted with a fluorine atom; specific examples thereof include alkyl groups having 1 to 4 carbon atoms which may be substituted with a fluorine atom, such as a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group and a trifluoromethyl group, with a hydrogen atom, a methyl group and a trifluoromethyl group being preferred. R ３２ represents a single bond or a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a heteroatom interposed therein, and part or all of the hydrogen atoms in said hydrocarbon group may be substituted with a group containing a heteroatom. R ３２ specific examples and preferred embodiments of R １２ are the same as those described above for R. R ３３ represents a divalent to tetravalent hydrocarbon group having 2 to 14 carbon atoms which may contain a fluorine atom, an oxygen atom or a sulfur atom; specific examples thereof include linear or branched saturated hydrocarbon groups having 2 to 4 carbon atoms such as an ethylene group and an isopropylene group, and saturated alicyclic hydrocarbon groups having 5 to 14 carbon atoms which may contain an oxygen atom or a sulfur atom and have a ring such as a cyclohexane ring, a norbornane ring, a 7-oxa-norbornane ring, a 7-thia-norbornane ring, an adamantane ring, and a tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane ring, with a cyclohexane ring, a norbornane ring and an adamantane ring being preferred. R ３４ represents a single bond or a divalent hydrocarbon group having 1 to 4 carbon atoms which may be substituted with a fluorine atom; specific examples thereof include alkylene groups having 1 to 4 carbon atoms which may be substituted with a fluorine atom, such as a single bond, a methylene group, a 1,1-ethylene group, a 2,2-propylene group, a 1,1,1,3,3,3-hexafluoro-2,2-propylene group, and a 1,1,1-trifluoro-2-trifluoromethyl-2,3-propylene group, with a single bond, a 1,1,1,3,3,3-hexafluoro-2,2-propylene group and a 1,1,1-trifluoro-2-trifluoromethyl-2,3-propylene group being preferred. R ３３ is an adamantyl group, R ３４A combination in which is a single bond is particularly preferred. k represents an integer of 1 to 3. Similarly, preferred examples of the structural unit (C) having a carboxyl group include a structure represented by formula (C2). In formula (C2), R ３５ represents a hydrogen atom, or a hydrocarbon group having 1 to 4 carbon atoms which may be substituted with a fluorine atom. Specific examples thereof include an alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, such as a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and a trifluoromethyl group, and a hydrogen atom, a methyl group, and a trifluoromethyl group are preferred. R ３６ 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 the hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom. R ３６ specific examples and preferred examples thereof are the same as those of the aforementioned R １２ . R ３７ represents a divalent alicyclic hydrocarbon group having 6 to 12 carbon atoms which may contain an oxygen atom or a sulfur atom. Specific examples thereof include an alicyclic hydrocarbon group which may contain an oxygen atom or a sulfur atom and has a norbornane ring, a 7-oxa-norbornane ring, a 7-thia-norbornane ring, a tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane ring, etc., and a norbornane ring and a tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane ring are preferred. k' represents an integer of 0 or 1.

[0025] Specific examples of the structural unit (C) are shown below, but the present invention is not limited thereto. One type or a plurality of types having different structures can be selected and used from the structural unit (C). (wherein, Rx represents H, CH ３ or CF ３ ).

[0026] (Structural unit (D) having a structure in which a carboxyl group is protected by an acid-stable dissolution inhibitory group) Structural unit (D) having a structure in which a carboxyl group is protected by an acid-stable dissolution inhibitory group that protects a carboxyl group derived from an acrylic monomer. Preferably, it is a structural unit in which a carboxyl group in a structural unit derived from (meth)acrylic acid is protected by an acid-stable dissolution inhibitory group. This structural unit provides a function to control solubility in lithography solvents and alkaline developers, as well as optical properties such as the refractive index and light transmittance of the thin film.

[0027] Examples of acid-stability dissolution-inhibiting groups include aliphatic hydrocarbon groups having 1 to 12 carbon atoms, aromatic hydrocarbon groups, or structures in which a methyl group and a 1-adamantyl group are bonded, with the carbon atom substituted for the hydrogen atom of a carboxyl group or phenolic hydroxyl group and bonded to the oxygen atom being a primary or secondary carbon. Specifically, these include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, cyclopentyl group, cyclohexyl group, 2-norbornyl group, 2-isobornyl group, and 8-tricyclo[5.2.1.0 2,6 ] decanyl group, 1-adamantyl group, 2-adamantyl group, 4-tetracyclo[4.4.0.1 2,5 .1 7,10 Examples include dodecanyl group, phenyl group, benzyl group, naphthyl group, anthracenyl group, etc.

[0028] The following are specific examples of structural units (D), but they do not limit the present invention. One type or multiple types of different structures can be selected and used from among these structural units (D). (In the formula, Rx is H, CH) ３ or CF ３ (This represents...)

[0029] Furthermore, a structural unit that has a similar effect to structural unit (D) can be given as the structural unit represented by formula (D'). In formula (D'), R ４０R represents a C1-C4 hydrocarbon group which may be substituted with a hydrogen atom or a fluorine atom. Specifically, examples include a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a trifluoromethyl group, and other C1-C4 alkyl groups which may be substituted with a fluorine atom. Preferably, it is a hydrogen atom, a methyl group, or a trifluoromethyl group. ４１ is a hydrogen atom, or R ４２ The single bond or alkylene group having 1 to 4 carbon atoms that is bonded to it, specifically, a hydrogen atom, a single bond, a methylene group, an ethylene group, an isopropylene group, etc. ４２ This refers to an aromatic hydrocarbon group having 6 to 14 carbon atoms, specifically including benzene rings, naphthalene rings, anthracene rings, and so on.

[0030] The following are specific examples of repeating units (D').

[0031] (Structural units derived from monomers other than acrylics) The polymer produced by the production method of the present invention may further contain structural units derived from monomers other than acrylics.

[0032] For example, structural units having a structure in which alkali-soluble groups such as carboxyl groups, hydroxyl groups, or sulfonic acid groups derived from monomers other than acrylics are protected by acid-dissociative dissolution inhibitors that dissociate upon the action of an acid. Preferably, these are structural units in which phenolic hydroxyl groups in structural units derived from hydroxystyrene, etc., are protected by acid-dissociative dissolution inhibitors. The following are specific examples of structural units having a structure in which alkali-soluble groups such as carboxyl groups, hydroxyl groups, or sulfonic acid groups derived from monomers other than acrylics are protected by acid-dissociative dissolution inhibitors that dissociate upon the action of an acid, but these examples are not intended to limit the present invention. One type or multiple types of different structures may be selected and used from among these structural units.

[0033] Furthermore, for example, structural units having a hydroxyl group or a carboxyl group, which are derived from monomers other than acrylics, are also mentioned. As such structural units, the structure represented by formula (D1) is preferred. In formula (D1), R ４３ R represents a hydrocarbon group having 1 to 4 carbon atoms that may be substituted with a hydrogen atom or a fluorine atom. Specifically, examples include a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a trifluoromethyl group, and other alkyl groups having 1 to 4 carbon atoms that may be substituted with a fluorine atom. Preferably, it is a hydrogen atom, a methyl group, or a trifluoromethyl group. ４４ R is a substituted or unsubstituted aromatic hydrocarbon group. ４５ l represents a single bond, or a divalent hydrocarbon group having 1 to 4 carbon atoms that may be substituted with a fluorine atom, or a carbonyl group. Specifically, examples include a single bond, a methylene group, a 1,1-ethylene group, a 2,2-propylene group, a 1,1,1,3,3,3-hexafluoro-2,2-propylene group, a 1,1,1-trifluoro-2-trifluoromethyl-2,3-propylene group, and other alkylene groups having 1 to 4 carbon atoms that may be substituted with a fluorine atom. Preferably, it is a single bond, a 1,1,1,3,3,3-hexafluoro-2,2-propylene group, or a 1,1,1-trifluoro-2-trifluoromethyl-2,3-propylene group, and particularly preferably a single bond. l represents an integer of 1 or 2.

[0034] The following are specific examples of structural units (D1), but they do not limit the present invention. One type or multiple types of different structures may be selected and used from among these structural units.

[0035] (Polyvalent acrylate crosslinking agent) The polyvalent acrylate crosslinking agent used in the present invention can be a bifunctional or more acrylate-based compound, for example, a compound having at least two (meth)acryloyl groups. More specifically, a compound having a structure in which at least two (meth)acrylic acid tertiary alkyl esters are linked via an organic group at one alkyl group bonded to each tertiary carbon atom. [R in the formula] 1 is the aforementioned R １１ It has similar provisions, R 3 and R 4 R is an alkyl group having 1 to 5 carbon atoms, n is an integer from 1 to 3, and A is a single bond or an organic group with (n+1) valency. 1 , R 3 and R 4 They may be the same or different.

[0036] R １ An example of this is the aforementioned R １１ Similar examples can be given, R ３ and R ４ Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and n-pentyl groups. A is an organic group having a single bond or (n+1) bonds, preferably a hydrocarbon group having 1 to 20 carbon atoms. Examples of hydrocarbon groups when n is 1 include linear or branched alkylene groups, cycloalkylene groups, or arylene groups. Examples of hydrocarbon groups when n is 2 include trivalent groups obtained by removing one hydrogen atom from the alkylene, cycloalkylene, or arylene groups mentioned above. Examples of hydrocarbon groups when n is 3 include tetravalent groups obtained by removing two hydrogen atoms from the alkylene, cycloalkylene, or arylene groups mentioned above. Particularly preferred polyvalent acrylate crosslinking agents are linear alkylene groups where A is 2 to 10, and R ３ and R ４ It is a methyl group.

[0037] Such polyvalent acrylates are derived from diesters, triesters, or tetraesters having two to four ethylenically unsaturated bonds, obtained by bonding two to four molecules of acrylic acid or methacrylic acid or their reactive functional derivatives, such as acid halides, to one molecule of alcohols having two to four hydroxyl groups, such as diols, triols, or tetrols, which have tertiary carbon atoms with hydroxyl groups bonded to each terminal.

[0038] Examples of the above diols include 2,3-dimethyl-2,3-butanediol, 2,3-diethyl-2,3-butanediol, 2,3-di-n-propyl-2,3-butanediol, 2,4-dimethyl-2,4-pentanediol, 2,4-diethyl-2,4-pentanediol, 2,4-di-n-propyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-diethyl-2,5-hexanediol, 2,5-di-n-propyl-2,5-hexanediol, 2,6-dimethyl-2,6-heptanediol, 2,6-diethyl-2,6-heptanediol, and 2,6-di-n-propyl Examples of glycols include ru-2,6-heptanediol, triols such as 2,4-dimethyl-2,4-dihydroxy-3-(2-hydroxypropyl)pentane, 2,4-diethyl-2,4-dihydroxy-3-(2-hydroxypropyl)pentane, 2,5-dimethyl-2,5-dihydroxy-3-(2-hydroxypropyl)hexane, and 2,5-diethyl-2,5-dihydroxy-3-(2-hydroxypropyl)hexane, and tetrols such as erythritol, pentaerythritol, and 2,3,4,5-hexanetetrol.

[0039] These polyvalent acrylates are preferably diacrylates, and more preferably, a general formula [R in the formula] 1 , R 3 and R 4 The same meaning as above, where p is 0, 1, or 2. ] And more preferably, the general formula [R in the formula] 1This has the same meaning as above, and p is 0, 1, or 2.

[0040] Furthermore, the polyvalent acrylate crosslinking agent of the present invention forms part of the structural unit of the polymer of the present invention by polymerizing with monomers such as the acrylic monomer, but is not included in one embodiment of the acrylic monomer.

[0041] (Weight-average molecular weight Mw and molecular weight distribution Mw / Mn of the polymer) The weight-average molecular weight Mw of the polymer produced by the manufacturing method of the present invention is 20,000 or more, preferably 20,000 to 100,000, and more preferably 20,000 to 50,000. The molecular weight distribution Mw / Mn of the polymer is preferably 2.0 to 7.0, and more preferably 3.0 to 6.0. If the weight-average molecular weight and molecular weight distribution of the polymer are within the above numerical ranges, it can be suitably used in lithography to form fine patterns in the range of several μm to tens of μm film thickness.

[0042] (Process of supplying raw materials and carrying out polymerization reaction) This process is a process of supplying raw materials containing an acrylic monomer, a radical polymerization initiator, and a polyvalent acrylate crosslinking agent into a system and carrying out a polymerization reaction, wherein in the supply process, during the time period when the amount of raw materials supplied is 40% to 100% of the total supply, the molar ratio of the amount of polyvalent acrylate crosslinking agent supplied to the amount of radical polymerization initiator consumed is adjusted to satisfy 4.6 or less.

[0043] The raw materials supplied in this supply process are subjected to a polymerization reaction. 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, and radical polymerization is preferred. As for the supply method in this process, for example, the raw materials can be dissolved in a solvent to form a solution, and the solution can be added dropwise or pre-filled into a reaction vessel. In the case of radical polymerization, the monomer, radical polymerization initiator, etc., 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 dropwise polymerization method, in which a solution containing 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 it can also be carried out by a so-called independent dropwise method in which the monomer and the polymerization initiator, which is a radical source, are added dropwise separately.

[0044] Furthermore, the monomers, crosslinking agents, polymerization initiators, etc., contained in the raw materials can be supplied not only by the dropwise method, but also partially supplied to the polymerization system in advance. In the dropwise method, the monomer concentration and radical concentration in 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. Details of the composition of the monomer solution and the supply speed will be described later in "(Molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed)".

[0045] 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 alone or in combination. The amount of polymerization initiator used is adjusted so that the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is 4.6 or less. The method for measuring the consumption amount of the radical polymerization initiator will be described later in "(Molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator)".

[0046] When a solvent is used in the supply process, the solvent is not particularly limited as long as it can stably dissolve the monomer, polymerization initiator, 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.

[0047] Polymerization solvents can be used alone or as a mixture of two or more. Alternatively, a mixture of compounds with high solubility and high boiling points, such as 3-methoxy-3-methyl-1-butyl acetate, ethyl 3-ethoxypropionate, γ-butyrolactone, diethylene glycol dimethyl ether, N-methylpyrrolidone, and dimethyl sulfoxide, may be used, along with monomers, polymerization initiators, and the resulting polymer.

[0048] 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.

[0049] 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.

[0050] 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 dropped 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 the productivity may decrease. In this invention, the dropping time is preferably 3 hours or more and 24 hours or less, more preferably 3 hours or more and 12 hours or less, and even more preferably 3 hours or more and 8 hours or less.

[0051] The polymerization temperature can be appropriately selected depending on the boiling point of the solvent and monomers, the half-life temperature of the polymerization initiator, etc. 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 preferably selected in the range of 40°C to 160°C, more preferably 60°C to 120°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.

[0052] 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.

[0053] (Molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed) In the production method of the present invention, during the supply process, the molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed is adjusted to satisfy a value of more than 1.0 and 4.6 or less during the time period when the amount of the raw materials supplied is 40% or more and 100% or less of the total supply (hereinafter, "the molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed" may also be referred to as "parameter"). The parameter is preferably 1.5 or more and 4.6 or less, more preferably 1.8 or more and 4.6 or less, and even more preferably 2.0 or more and 4.6 or less. By keeping the parameter within the above numerical range, the polymerization reaction can proceed suitably while suppressing excessive crosslinking.

[0054] In the supply process, there are no particular restrictions on the raw material supply method, as long as the parameters are adjusted within a predetermined numerical range. For example, in the middle or later stages of the supply process (for example, during the period when the amount of raw materials supplied is between 40% and 100% of the total supply), the conditions for supplying raw materials may be changed in order to adjust the parameter ratio within a predetermined numerical range. One example is to limit the raw material supply rate relative to the consumption rate of raw materials such as polyvalent acrylate crosslinking agents, thereby increasing the supply time.

[0055] The amount of polyvalent acrylate crosslinking agent supplied is preferably 2.0 moles or more and 10.0 moles or less per 100 moles of the total supply of the acrylic monomer.

[0056] During the time period when the supply of raw materials is 40% to 50% of the total supply, the molar ratio of the supply of the polyvalent acrylate crosslinking agent to the consumption of the radical polymerization initiator is preferably greater than 3.0 and less than or equal to 4.6. Furthermore, at the point when the supply of raw materials is 100% of the total supply, the molar ratio of the supply of the polyvalent acrylate crosslinking agent to the consumption of the radical polymerization initiator is preferably greater than 1.8 and less than 3.3.

[0057] (Step to estimate the consumption rate of the radical polymerization initiator) Estimate the consumption rate of the radical polymerization initiator in advance: In the manufacturing method of the present invention, a step to estimate the consumption rate of the radical polymerization initiator may be performed prior to carrying out the manufacturing method of the present invention. Depending on the estimation result, the amount of raw materials supplied per unit time and the amount of radical polymerization initiator used are adjusted so that the molar ratio of the amount of polyvalent acrylate crosslinking agent supplied to the amount of radical polymerization initiator consumed during the time period when the amount of raw materials supplied is 40% or more of the total supply amount is 100%, is greater than 1.8 and less than or equal to 4.6. There are no particular restrictions on the method of estimation, but examples include (I) estimation by a preliminary test performed in advance of the supply step, and (II) estimation by calculation.

[0058] (I) Method of estimation by preliminary testing The method is performed by measuring the consumption of the radical polymerization initiator during the time period in which the supply amount of the raw materials of the present invention is between 40% and 100% of the total supply amount. If the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator during the time period is greater than 4.6, the supply time or the amount of the radical polymerization initiator used is set by extending the supply time of the raw materials or increasing the amount of the radical polymerization initiator used.

[0059] (II) Method of estimation by calculation This method can be carried out by following the procedure described in paragraphs

[0041] -

[0042] of Japanese Patent Publication No. 2013-103997. That is, the supply rate of the polymerization initiator is determined by simulating how the concentration of the polymerization initiator changes in the reaction system based on a general method for calculating the half-life, so that the range of change in the polymerization initiator concentration in the polymerization solution during the time period from when the monomer supply amount reaches 10% to when the supply ends is within ±25% of the average value during that period. Assuming a case where only the solvent is placed in the reaction vessel and heated to the polymerization temperature, a solution containing a portion of the polymerization initiator is supplied first, and then the solution containing the monomer and the solution containing the remaining polymerization initiator are supplied dropwise, the simulation is specifically carried out by the following procedure (1) to (3). (1) Calculate the change in the amount of polymerization initiator in the reaction system. If J0 (g) is the amount of polymerization initiator supplied before the start of monomer supply, T (min) is the half-life of the polymerization initiator at the polymerization temperature, and K (g / min) is the supply rate of the polymerization initiator, then the amount of polymerization initiator remaining in the reaction system after 1 minute of heating is expressed as J0 * exp(-ln2 / T). Furthermore, since the amount added later is heated for an average of 0.5 minutes while being supplied over 1 minute, the amount of polymerization initiator added per minute is expressed as K * exp(-ln2 * 0.5 / T). Therefore, the amount of polymerization initiator remaining J1 after 1 minute is J1 = J0 * exp(-ln2 / T) + K * exp(-ln2 * 0.5 / T) Similarly, the amount of polymerization initiator remaining J2 after 2 minutes is J2 = J1 * exp(-ln2 / T) + K * exp(-ln2 * 0.5 / T) By repeating the same calculation thereafter, the amount of polymerization initiator remaining in the reaction system after a predetermined time can be determined. The value of the half-life T of the polymerization initiator necessary for the calculation can be obtained by referring to materials such as the manufacturer's catalog. Also, since the decomposition rate of the polymerization initiator may change depending on the type of solvent, in order to obtain a more accurate value, it is preferable to conduct an experiment in which the polymerization initiator is dissolved in a predetermined solvent, heated at a predetermined temperature, and the change in concentration is measured to determine the half-life T. (2) Calculate the change in the liquid volume in the reaction vessel. The amount of solvent to initially fill the reaction vessel is L ０－１ (g) The amount of polymerization initiator solution supplied before supplying monomers is L ０－２(g) If the supply rate of polymerization initiator solution is M (g / min) and the supply rate of monomer solution is N (g / min), then the volume of liquid L1 in the reaction vessel after 1 minute is L1 = (L ０－１ ) + (L ０－２ ) + M + N. The liquid volume L2 in the reaction vessel after 2 minutes is L2 = L1 + M + N. The liquid volume after a predetermined time can be calculated in the same manner thereafter. (3) Calculate the concentration of polymerization initiator in the polymerization solution. Based on the calculation results of (1) and (2), the polymerization initiator concentration I1 in the polymerization solution after 1 minute is expressed as I1 = J1 / L1. The polymerization initiator concentration I2 in the polymerization solution after 2 minutes is expressed as I2 = J2 / L2. The polymerization initiator concentration in the polymerization solution after a predetermined time can be calculated in the same manner thereafter. Next, a graph is created with time on the horizontal axis and the polymerization initiator concentration in the polymerization solution on the vertical axis, and a supply rate is simulated such that the change in the concentration of polymerization initiator in the polymerization solution during the time period from when the monomer supply amount is 10 mol% of the total monomer supply amount to when the supply ends is within ±25% of the midpoint between the maximum and minimum concentrations during that period. By graphing, the changes in the polymerization initiator concentration can be visually confirmed. The above calculations can be easily performed using spreadsheet software on a personal computer.

[0060] (Conversion Rate) The conversion rate of raw materials such as monomers and polyvalent acrylate crosslinking agents can be confirmed by measuring the concentration of the monomers in the raw materials. It is preferable to confirm the conversion rate and increase the raw material supply time to increase the conversion rate, thereby keeping the concentrations of unreacted monomers and unreacted crosslinking agents in the system low during the middle of the polymerization reaction when the crosslinking reaction occurs. For example, it is preferable to measure the consumption of monomers and crosslinking agents during the time when the supply amount of raw material monomers and crosslinking agents is between 40% and 100% of the total, and set the conversion rate of monomers and crosslinking agents to 65% or higher.

[0061] Furthermore, the "conversion rate" of the above monomers, etc., during the time until the supply reaches X% of the total, refers to the ratio of the monomers, etc., that have been converted to the supply amount up to that time, calculated by subtracting the amount of unreacted monomers, etc., from the supply amount. As an example, the formula for calculating the monomer conversion rate during the time until the supply reaches X% of the total is shown below: Conversion rate = (Amount of monomers supplied up to the time when the supply reaches X% of the total - Amount of unreacted monomers) / (Amount of monomers supplied up to that time)

[0062] For example, if the supply of a certain monomer is recorded at 20% intervals, the conversion rate of that monomer during the time period when the supply of that monomer is between 60% and 80% of the total refers to either the proportion of converted monomers out of the supply (60% of the total) or the proportion of converted monomers out of the supply (80% of the total). Similarly, for example, the conversion rate of that monomer during the time period when the supply of that monomer is between 40% and 100% of the total refers to either the proportion of converted monomers out of the supply (40% of the total), the proportion of converted monomers out of the supply (60% of the total), the proportion of converted monomers out of the supply (80% of the total), or the proportion of converted monomers out of the supply (100% of the total). Therefore, for example, if the monomer is supplied to a reaction system after a time has elapsed when the supply amount of the monomer is 60% of the total, but the monomer does not convert, the conversion rate of the monomer during the time period when the supply amount is 80% of the total may be lower than the conversion rate during the time period when the supply amount is 60%, because the unreacted monomer is included in the denominator of the conversion rate.

[0063] Furthermore, the "conversion rate" of the monomers, etc., after the completion of the supply process refers to the ratio of the converted monomers, etc., to the total amount supplied, calculated by subtracting the amount of unreacted monomers, etc., from the total amount supplied. As an example, the formula for calculating the monomer conversion rate after the completion of the supply process is shown below: Conversion rate = (Total amount supplied - Amount of unreacted monomers) / (Total amount supplied)

[0064] The formula for calculating the conversion rate after the above supply process is used, for example, when determining the monomer conversion rate in the acceleration process and subsequent processes described later.

[0065] Furthermore, when multiple types of monomers are used, the conversion rate is calculated based on the total amount of all types of monomers used.

[0066] The manufacturing method of the present invention may be carried out in the absence of a chain transfer agent. Normally, excessive crosslinking of the polymer is suppressed by using a chain transfer agent, but in the manufacturing method of the present invention, by adjusting the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator, excessive crosslinking of the polymer can be suppressed without using a chain transfer agent.

[0067] In configurations using chain transfer agents, known chain transfer agents can be used as needed. Examples include thiol compounds, which can be selected from among known thiol compounds. 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 have the effect of suppressing roughness and defects in lithography patterns.

[0068] On the other hand, forms that do not use chain transfer agents have the advantage of not requiring the use of thiol compounds, which are the source of odor. 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.

[0069] (Step to further promote polymerization reaction after the completion of the supply step) After the completion of the supply step, it is preferable to promote the polymerization reaction by maintaining the temperature for a certain period of time or further increasing the temperature, and to react any remaining unreacted monomers (hereinafter, this step will also be referred to as "promotion"). This promotion step allows the monomers to react sufficiently and increases the conversion rate. This promotion step is carried out until the amount of monomers present is at least 25.0 mol% or less of the monomers present at the start of the promotion step.

[0070] In the acceleration step, polymerization initiators may be added to further react the raw materials such as monomers. For example, a radical polymerization initiator may be added at the start of the acceleration step.

[0071] If the acceleration process is performed for too long, the production efficiency per unit of time may decrease, or the polymer may be subjected to an unnecessary amount of heat history. Therefore, as an example, it is usually selected from within 12 hours, preferably within 8 hours, and particularly preferably within 1 to 6 hours.

[0072] The amount of monomer present in the acceleration step is at least 25.0 mol% or less of the monomer at the start of the acceleration step, preferably 20.0 mol% or less, more preferably 15.0 mol% or less, and even more preferably 10.0 mol% or less.

[0073] (Weight-average molecular weight Mw of the polymer after the acceleration step) The change in the weight-average molecular weight Mw of the polymer from the weight-average molecular weight Mw at the end of the acceleration step to the weight-average molecular weight Mw after the acceleration step, relative to the weight-average molecular weight Mw at the start of the acceleration step, is less than 5.0%. The manufacturing method of the present invention suppresses excessive crosslinking of the polymer and prevents an excessive increase in the weight-average molecular weight of the polymer before and after the acceleration step by adjusting the molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed during a specific time period in the supply step to be within a predetermined numerical range.

[0074] (Other steps) After the acceleration step is completed, the manufacturing method of the present invention may further carry out other steps as necessary.

[0075] (Step to decompose unreacted polymerization initiator) The manufacturing method of the present invention may also include a step to decompose unreacted polymerization initiator (hereinafter also referred to as the "decomposition step") after the acceleration step is completed. In embodiments in which additional polymerization initiator is added in the acceleration step, a larger amount of unreacted polymerization initiator may remain, so the decomposition step can suitably reduce the remaining amount of unreacted polymerization initiator.

[0076] In the decomposition step, the temperature of the reaction system may be raised. For example, the temperature may be raised further from the polymerization temperature by +5 to 50°C, preferably +10 to 30°C, and more preferably +15 to 25°C.

[0077] The end point of the decomposition process may be, for example, when unreacted polymerization initiators are no longer detectable in the evaluation system used to carry out the manufacturing method of the present invention.

[0078] If the decomposition process is performed for too long, the production efficiency per unit time may decrease, and the polymer may be subjected to more heat history than necessary. Therefore, as an example, it is usually selected from within 12 hours, preferably within 8 hours, and particularly preferably within 1 to 6 hours. Similarly, the rate at which the temperature is raised in the decomposition process may be set to, for example, 5°C to 50°C per hour, preferably 10°C to 40°C per hour, and more preferably 15°C to 30°C per hour, taking into consideration the production efficiency and heat history.

[0079] The monomer conversion rate is preferably 70% or more at the end of the supply step and 90% or more at the end of the acceleration step. More specifically, the monomer conversion rate is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more at the end of the supply step. Similarly, the monomer conversion rate is preferably 90% or more, more preferably 92% or more, and even more preferably 94% or more at the end of the acceleration step. Furthermore, if the manufacturing method of the present invention includes a step of decomposing the unreacted polymerization initiator, the monomer conversion rate is preferably 94% or more, more preferably 96% or more, and even more preferably 98% or more at the end of the decomposition step.

[0080] [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.

[0081] The embodiments of the present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to these examples. Unless otherwise specified in the following examples, parts are measured by mass.

[0082] The analysis in this example was performed as follows: [Weight-average molecular weight and molecular weight distribution of polymer] The weight-average molecular weight and molecular weight distribution 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. Measuring instrument: Tosoh HLC-8320GPC Detector: Differential refractive index (RI) detector Column: Shodex GPC LF804 x 3 (Resonac) Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min Temperature: 40°C Calibration curve: Created using a polystyrene standard sample (Tosoh) [Analysis of residual amounts of monomers and polymerization initiators during polymerization reaction and calculation method of conversion rate] In the polymerization reaction experiment below, the quantitative analysis of low molecular weight components, including monomers and polymerization initiators during the polymerization reaction, was performed by LC (liquid chromatography). Measurement device: Waters e2695 (Waters Corporation) Detector: UV (210 nm) Detector column: Waters XBridge C18 x 1 Eluent: 0.16% acetonitrile phosphoric acid aqueous solution Flow rate: 1.0 mL / min Temperature: 40°C The sample used for analysis was prepared to be a tetrahydrofuran solution with a polymer solid content of 2% by mass. The sample volume injected into the instrument was 50 μL.

[0083] (Abbreviations for compounds) The abbreviations for the compounds used in the following experiment are as follows: THF: Tetrahydrofuran MBA: Methoxybutyl acetate MA: Methacrylic acid ECHA: 1-Ethyl-1-cyclohexyl acrylate TCDMA: Tricyclodecane methacrylate GBLMA: Gamma-butyrolactone methacrylate MDA25: 1,1,4,4-Tetramethyl-1,4-butanediol diacrylate

[0084] [Polymerization Procedure] Droplet polymerization and reaction analysis of the examples and comparative examples were performed as follows.

[0085] (A process in which raw materials are supplied into the system and polymerization reactions are carried out) N ２In a 500 mL flask reactor equipped with a supply line, stirrer, thermometer, condenser, and reflux solvent extraction line, 63 g of MBA solvent and 27 g of acetone were added, and the system was subjected to N2. ２ The flask reactor was purged with gas and heated in an oil bath to a liquid temperature of 78°C. In a separate container, four types of acrylic monomers, the crosslinking agent diacrylate MDA25, and the polymerization initiator V-601 were weighed to the weight and molar ratios listed in Table 1, and dissolved in 39 g of solvent MBA and 24 g of acetone to prepare the dropper solution for dropper polymerization. In terms of weight, the total amount of the four types of acrylic monomers was standardized at 85 g. The amount of the crosslinking agent MDA25 was 3.8 g in Example 1, and in experiments from Example 4 onwards, it was adjusted proportionally to the values ​​in Table 1. The amount of polymerization initiator V601 was 3.5 g in Example 1, and in other examples, it was increased or decreased proportionally to the values ​​in Table 1. The container of the dropper solution was N ２ The oxygen is removed by bubbling with gas, and the container for the dropper solution remains N afterwards. ２ The atmosphere was maintained. The dropping solution was supplied at a constant rate from a container to the reactor, which was heated to a temperature of 78°C, using a metering pump, and the supply of raw materials was adjusted so that it was completed within the time shown in Table 1. The dropping time for the raw materials was 2.5 hours in the shortest comparative example 1 and 8.75 hours in the longest example 3.

[0086]

[0087] The total weight of monomers other than the crosslinking agent is 85 g, and the monomer molar ratio is MA / TCDMA / ECHA / GBLMA = 18 / 31 / 27 / 21, totaling 97 moles. The monomer conditions are the same for all examples and comparative examples.

[0088] While raw materials are being supplied, N is present inside the reactor. ２ The atmosphere was maintained, and the temperature was kept at 78-81°C. During the supply of raw materials, a portion of the contents was sampled at predetermined intervals as shown in Table 2, and the remaining amounts of unreacted monomers, crosslinking agents, and polymerization initiators were measured. The GPC molecular weight of the polymer formed up to that time was also measured. Sampling and analysis were also performed when all the raw materials had been supplied.

[0089] (Step to further accelerate the polymerization reaction) Next, to increase the monomer conversion rate, an initiator was added to accelerate the polymerization reaction. Two solutions were prepared by dissolving a predetermined amount of polymerization initiator V601 (0.1 times the amount used when preparing the dropwise solution as described in Table 1, which is 0.35 g in Example 1) in 2.7 g of solvent MBA and 1.4 g of acetone. These solutions were added dropwise at 30 minutes and 60 minutes after the completion of raw material supply, respectively. The temperature inside the reactor was maintained at 79°C ± 1°C for 2 hours after the completion of raw material supply. Sampling was performed at the timings shown in Table 2.

[0090] (Step to decompose unreacted polymerization initiator) Next, for Example 1 and Comparative Example 1, a step to decompose the unreacted polymerization initiator was carried out. The temperature of the oil bath was increased, and the temperature inside the reactor was raised to 97°C over 1 hour. At this time, a portion of the solvent was discharged from the system through the reflux outlet of the condenser. After the temperature was raised, the solution temperature was maintained at 97°C ± 2°C for 1.5 hours to completely decompose the unreacted polymerization initiator. After that, the solution was cooled and a portion of the contents was sampled. The remaining amounts of unreacted monomers, crosslinking agent and polymerization initiator were measured, and the GPC molecular weight of the polymer was measured.

[0091]

[0092] In all of Examples 1 to 6, the monomer conversion rate was 70% or higher at the end of the supply process and 90% or higher at the end of the acceleration process. Furthermore, in Example 1, where a decomposition process was carried out, the monomer conversion rate at the end of the decomposition process was 98% or higher. In addition, the conversion rate of the crosslinking agent was 70% or higher at the end of the supply process and 90% or higher at the end of the acceleration process in all of Examples 1 to 6. Furthermore, in Example 1, where a decomposition process was carried out, the conversion rate of the crosslinking agent at the end of the decomposition process was 98% or higher. These conversion rate results will be described later for each example. The copolymer obtained in this experiment is a solution of a mixed solvent of MBA and acetone. After this, by removing the low-boiling point solvent under reduced pressure and adding MBA to adjust the concentration, a high-viscosity polymer solution diluted with a photoresist coating solvent can be obtained.

[0093] [Comparison of Example 1 and Comparative Example 1] An example of the results of analyzing the relationship between polymerization time and molecular weight is shown. Comparative Example 1 and Example 1 are exactly the same in terms of raw material usage and polymerization acceleration procedure, except that the dropping time for dropwise polymerization differs between 2.5 hours and 3.5 hours. In Comparative Example 1, excessive crosslinking occurs in the latter half of the polymerization reaction, leading to increased molecular weight, but this phenomenon is not observed in Example 1, and the change in molecular weight during the polymerization acceleration procedure remains at a slight increase.

[0094]

[0095] Figure 1 shows the change in molecular weight over time from the start of the supply process to the end of the acceleration process for Comparative Example 1 and Example 1. Here, the horizontal axis represents time, and the time taken for dropping is set to 1. The horizontal axis also coincides with the supply ratio of monomer raw materials, and it can be seen that there is little difference between the comparative example and the example when the raw material supply ratio is around 0.3 to 0.4, and that a difference in molecular weight becomes apparent in the time period when the raw material supply ratio is 0.5 or higher.

[0096] This report shows the results of sampling during dropwise polymerization to measure the remaining amounts of unreacted monomers, crosslinking agents, and polymerization initiators. The results are expressed in the form of raw material supply ratio and raw material conversion rate. The formula for calculating the conversion rate is as follows: The monomer conversion rate is expressed as the total for the four types of acrylic monomers. Conversion Rate = (Raw materials supplied up to that time - Unreacted raw materials) / (Raw materials supplied up to that time)

[0097]

[0098] Figure 2 shows a table illustrating the conversion rates of monomers and crosslinking agents for comparison. Comparative Example 1 had a lower conversion rate of monomers and crosslinking agents than Example 1. In particular, the conversion rate was somewhat low during the period when the raw material supply amount was between 40% and 75%, where a significant difference in molecular weight began to be observed. It is conceivable that the concentration of unreacted monomers and crosslinking agents in the system was high during the middle of the dropwise polymerization, which was the source of excessive crosslinking polymerization. Since excessive crosslinking did not occur in Example 1, it is suggested that a monomer conversion rate of 65% or higher is preferable at the point when the raw material supply amount is 3 / 7 (43%) during the middle of the dropwise polymerization.

[0099] Next, we consider the role of radical polymerization initiators in regulating the molecular weight of polymers. Since the radical generation rate of radical polymerization initiators also depends on the temperature in the system, stoichiometry is considered based on the amount consumed in the system rather than the amount supplied. The parameter for preventing excessive crosslinking is expressed as the "molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed" during the time period corresponding to the raw material supply ratio. (Hereafter, the "molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed" will also be referred to as the "parameter.")

[0100] The amount of crosslinking agent supplied = the total number of moles of crosslinking agent supplied into the reaction system up to that time. From Table 1, in Comparative Example 1 and Example 1, it can be calculated as 3 × raw material supply ratio. That is, when the raw material supply ratio is 0.20, the number of moles of raw material monomer is 97 mol × 0.20 = 19.4 mol, so the number of moles of crosslinking agent used for 97 mol of monomer is 0.20 × 97 mol (monomer) × 3 mol (crosslinking agent) / 97 mol (monomer) = 0.20 × 3 mol (crosslinking agent). The same applies to other raw material supply ratios. The amount of initiator consumed = moles of initiator supplied into the reaction system up to that time × conversion rate of the initiator. Note that in the very early stages of dropwise polymerization, the amount of crosslinking agent and initiator consumed is analyzed from a dilute solution and the conversion rate is low, so the error is large, but from the middle of dropwise polymerization onwards, sufficient quantitative analysis was possible.

[0101]

[0102] The larger the parameter value, the larger the molecular weight of the polymer; the smaller the parameter value, the less likely crosslinking is to occur. In Comparative Example 1, the parameter value exceeds the threshold of 4.6 at the midpoint, when the raw material supply is at 40%, with a parameter value of 5.0. However, in Example 1, the parameter value is 4.6 or less during the period from the midpoint, when the raw material supply is at 40%, to 100%.

[0103] [Comparison of Examples 2 and 3, and Comparative Example 2] Examples 2 and 3, and Comparative Example 2, were charged with the same molar amounts of monomer and crosslinking agent as Example 1, but the dropping time was extended to more than twice the original time, aiming for monomer consumption rate > dropping rate. The monomer conversion rate was increased up to the middle stage to keep the monomer concentration in the system low, and in exchange, the polymerization initiator was reduced to adjust the parameters to appropriate values, resulting in the highest possible molecular weight, a narrow molecular weight distribution, and a design to prevent excessive crosslinking. In Examples 2 and 3, the final molecular weight distribution Mw / Mn value was smaller than in Example 1, but in Comparative Example 2, where the balance between initiator amount and dropping rate was not good, polymerization due to excessive crosslinking progressed.

[0104]

[0105]

[0106] The relationship between time and conversion rate for Examples 2 and 3 and Comparative Example 2 is shown in the table. There were no particularly significant differences, and as pointed out in Example 1, the monomer conversion rate exceeded 70% at a time of 40% or more raw material supply. The molecular weight parameter was calculated as moles of crosslinking agent supply / moles of initiator consumption. In Examples 2 and 3, the parameter value was generally less than 4.0 to around 3.0 from the middle of the polymerization reaction onward, after the raw material supply amount was 0.43, but in Comparative Example 2, the parameter reached 4.8 in the middle (when the raw material supply amount was 0.43), exceeding the threshold of 4.6. This is thought to be the cause of excessive crosslinking.

[0107]

[0108] [Comparison of Examples 4 and 5 and Comparative Example 3] Examples 4 and 5 and Comparative Example 3 were charged with the same monomer molar amount as Example 1, but with the amount of crosslinking agent doubled to 6 moles. In Example 4, when the amount of crosslinking agent and initiator was doubled, a polymer similar to that of Example 1 was obtained. In Comparative Example 3, where the amount of polymerization initiator used was reduced to 0.75 times, excessive crosslinking occurred. In Example 5, when the dropping time was increased by 1.5 times instead of using the same raw materials as Comparative Example 3, the molecular weight decreased and excessive crosslinking did not occur.

[0109]

[0110] When the relationship between raw material supply amount and conversion rate was examined for Examples 4 and 5 and Comparative Example 3, it was found that, as pointed out in Example 1, the conversion rate between monomers and crosslinking agents exceeded 70% during the time when the raw material supply was 40% or more.

[0111]

[0112] In Examples 4 and 5, the parameter values ​​were generally less than 4.0 to around 3.0 from the middle of the polymerization reaction onward, after the raw material supply rate reached 0.43. However, in Comparative Example 3, the parameter reached 5.3 in the middle of the reaction (when the raw material supply rate was 0.43), exceeding the threshold of 4.6. This is thought to have caused excessive crosslinking.

[0113]

[0114] [Comparison of Example 6 and Comparative Examples 4 and 5] In Example 6, Comparative Examples 4 and 5, the same amount of monomer molars as in Example 1 was used, but the amount of crosslinking agent molars was doubled to 6 moles. In Example 6, the amount of polymerization initiator relative to the crosslinking agent was reduced, and instead the dropping time was increased. In Comparative Example 4, the dropping time was shorter than in Example 6, and in Comparative Example 5, the amount of polymerization initiator was reduced even further than in Example 6. Example 6 yielded a polymer comparable to that of Example 2. In Comparative Examples 4 and 5, excessive crosslinking occurred. In all three experiments, the conversion rate between monomer and crosslinking agent was approximately 80% or higher from the middle of the reaction onward, achieving the target conversion rate. The balance between the amount of initiator, the rate of initiator consumption, and the dropping time resulted in different outcomes depending on the parameter thresholds.

[0115]

[0116]

[0117]

[0118] Table 15 lists the endpoint of the acceleration process and the analytical properties of the obtained polymer. A "×" is marked for polymers with excessive crosslinking in the GPC form, and a "○" is marked for those without. "*1" represents the molar ratio of the amount of polyvalent acrylate crosslinking agent supplied to the amount of radical polymerization initiator consumed during the time period of the raw material supply ratio. Similarly, "*2" in Tables 16-17 represents the conversion rates of monomers (left column) and polyvalent acrylate crosslinking agents (right column) during the time period of the raw material supply ratio, as well as at the end of the acceleration process and the end of the decomposition process.

[0119]

[0120]

[0121] Based on the above, in a method for producing a polymer with a weight-average molecular weight Mw of 20,000 or more, in a step of supplying raw materials containing an acrylic monomer, a radical polymerization initiator, and a polyvalent acrylate crosslinking agent into a system and carrying out a polymerization reaction, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is adjusted to satisfy a value of more than 1.0 and 4.6 or less during the time period when the supply amount of the raw materials is 40% or more of the total supply amount and 100% or less. After the end of the supply step, a step to further accelerate the polymerization reaction is carried out until the amount of monomer present in the acceleration step is at least 25.0 mol% or less of the amount of monomer present at the start of the acceleration step. By doing so, the change in the weight-average molecular weight Mw of the obtained polymer from the weight-average molecular weight Mw at the end of the acceleration step to the weight-average molecular weight Mw after the acceleration step, relative to the weight-average molecular weight Mw at the start of the acceleration step, can be made to less than 5.0%.

[0122] The manufacturing method of the present invention can be suitably used to produce acrylic copolymers for photoresists having a molecular weight Mw of 20,000 or more.

Claims

1. A method for producing a polymer having a weight-average molecular weight Mw of 20,000 or more, comprising the steps of: supplying raw materials containing an acrylic monomer, a radical polymerization initiator, and a polyvalent acrylate crosslinking agent into a system and carrying out a polymerization reaction, wherein in the supply step, during the time period when the supply amount of the raw materials is 40% or more of the total supply amount until it reaches 100%, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 1.0 and less than or equal to 4.6; and after the end of the supply step, a step of further promoting the polymerization reaction, wherein the promotion step is carried out until the amount of monomer present in the promotion step is at least 25.0 mol% or less of the amount of monomer present at the start of the promotion step, and the change in the weight-average molecular weight Mw of the polymer from the weight-average molecular weight Mw at the end of the promotion step to the weight-average molecular weight Mw after the promotion step is less than 5.0% of the weight-average molecular weight Mw at the start of the promotion step.

2. The manufacturing method according to claim 1, wherein the total amount supplied of the polyvalent acrylate crosslinking agent is 2.0 moles or more and 10.0 moles or less per 100 moles of the total amount supplied of the acrylic monomer.

3. The manufacturing method according to claim 1 or 2, wherein in the supply step, the amount of raw materials supplied is further adjusted so that the conversion rate of the monomer and the polyvalent acrylate crosslinking agent is 65% or more during the time period when the amount of raw materials supplied is 40% or more of the total amount supplied.

4. The manufacturing method according to any one of claims 1 to 3, carried out in the absence of a chain transfer agent.

5. The manufacturing method according to any one of claims 1 to 4, wherein the monomer conversion rate is 70% or more at the end of the supply process and 90% or more at the end of the acceleration process.

6. The manufacturing method according to any one of claims 1 to 5, wherein, during the time period when the supply amount of the raw materials is 40% to 50% of the total supply amount, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 3.0 and less than or equal to 4.

6.

7. The manufacturing method according to any one of claims 1 to 6, wherein, at the point when the supply amount of the raw materials is 100% of the total supply amount, the molar ratio of the supply amount of the polyvalent acrylate crosslinking agent to the consumption amount of the radical polymerization initiator is greater than 1.8 and less than 3.

3.

8. The manufacturing method according to any one of claims 1 to 7, wherein the radical polymerization initiator is added at the start of the acceleration step.

9. The manufacturing method according to any one of claims 1 to 8, wherein the weight-average molecular weight Mw of the polymer is 50,000 or less.

10. The manufacturing method according to any one of claims 1 to 9, wherein the time of the supply process is 3 hours or more.

11. The manufacturing method according to any one of claims 1 to 10, wherein the duration of the acceleration step is 1 hour or more and 6 hours or less.

12. The manufacturing method according to any one of claims 1 to 11, wherein, before carrying out the polymer manufacturing method, the amount of raw materials supplied per unit time and the amount of radical polymerization initiator used are adjusted by the following preliminary test so that, during the time period when the amount of raw materials supplied is 40% or more of the total supply, the molar ratio of the amount of polyvalent acrylate crosslinking agent supplied to the amount of radical polymerization initiator consumed is greater than 1.8 and less than or equal to 4.

6. (Preliminary Test) In the supply process, the amount of the radical polymerization initiator consumed is measured during the time period when the amount of the raw material supplied is between 40% and 100% of the total supply amount. If the molar ratio of the amount of the polyvalent acrylate crosslinking agent supplied to the amount of the radical polymerization initiator consumed is greater than 4.6, the supply time or the amount of the radical polymerization initiator used is set by extending the supply time of the raw material or increasing the amount of the radical polymerization initiator used.

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