JP2012001625A - Polymer manufacturing method, polymer for semiconductor lithography, resist composition, and method of manufacturing substrate with pattern formed thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer manufacturing method capable of reducing an unreacted monomer component remaining in a polymer, without decreasing the productivity.SOLUTION: The polymer manufacturing method includes: a polymerization process for subjecting a monomer to polymerization reaction in a polymerization solvent in the existence of the polymerization initiator to generate the polymer; and a purification process for supplying the reaction solution, obtained by the polymerization process, to a poor solvent for reprecipitation. In the polymerization process, part or all of the monomer is supplied by dropping, and the mass of the polymerization solvent supplied for the polymerization reaction is 2.0 times or less of the mass of the entire monomer.

Description

  The present invention relates to a method for producing a polymer, a polymer for semiconductor lithography obtained by the production method, a resist composition using the polymer for semiconductor lithography, and a substrate on which a pattern is formed using the resist composition. It relates to a manufacturing method.

  In recent years, a resist pattern formed in a manufacturing process of a semiconductor element, a liquid crystal element, or the like has been rapidly miniaturized due to progress in lithography technology. As a technique for miniaturization, there is a reduction in wavelength of irradiation light. Specifically, the irradiation light has become shorter from conventional ultraviolet rays typified by g-line (wavelength: 438 nm) and i-line (wavelength: 365 nm) to shorter wavelength DUV (Deep Ultra Violet). .

  Recently, KrF excimer laser (wavelength: 248 nm) lithography technology has been introduced, and ArF excimer laser (wavelength: 193 nm) lithography technology and EUV (wavelength: 13.5 nm) lithography technology for further shortening the wavelength have been studied. . Furthermore, these immersion lithography techniques are also being studied. Also, as a different type of lithography technology, electron beam lithography technology has been energetically studied.

As a highly sensitive resist composition used for forming a resist pattern using such short-wavelength irradiation light or electron beam, a “chemically amplified resist composition” containing a photoacid generator has been proposed, Improvement and development of the chemically amplified resist composition are underway.
For example, as a chemically amplified resist polymer used in ArF excimer laser lithography, an acrylic polymer that is transparent with respect to light having a wavelength of 193 nm has attracted attention. As the acrylic polymer, for example, a polymer of (meth) acrylic acid ester having an adamantane skeleton in an ester portion and (meth) acrylic acid ester having a lactone skeleton in an ester portion has been proposed (Patent Document 1). etc).
In the method for producing an acrylic polymer described in the Examples of Patent Document 1 below, all of the monomers and a polymerization initiator are collectively supplied to a reaction vessel and stirred at a predetermined temperature to cause a polymerization reaction. Is the method.

  With the miniaturization of resist patterns, demands for quality of polymers for semiconductor lithography have become stricter. For example, if a large amount of unreacted monomer components remain in the polymer for semiconductor lithography, when used as a resist composition, for example, the light transmittance at the exposure wavelength is lowered, and sensitivity and resolution are reduced. Resist performance is likely to deteriorate, such as worsening.

  In Patent Document 2 below, all of the monomers and the polymerization initiator are collectively supplied to a reaction vessel, and the polymerization reaction is performed by stirring at a predetermined temperature, and the resulting polymer solution is poorly supplied from a nozzle having a specific diameter. A method is described in which it is fed into a solvent for precipitation or reprecipitation. According to this method, a polymer in which the content of monomers contained as impurities in the polymer is reduced to 2% by mass or less can be obtained, and when this is used as a resist composition, a high resist is obtained. It is described that performance can be obtained.

JP 10-319595 A JP 2007-051299 A

  However, the method described in Patent Document 2 is a method in which the amount of monomer removed in the purification step is increased simply by changing the conditions for performing the purification step by precipitation or reprecipitation after the polymerization reaction. Therefore, if it is attempted to reduce the monomer remaining in the polymer by this method, the amount of monomer removed in the purification process increases, so that the final polymer (including impurities) is obtained. The yield of becomes worse. That is, the productivity of the polymer is lowered.

  The present invention has been made in view of the above circumstances, and a method for producing a polymer capable of reducing unreacted monomer components remaining in the polymer without reducing productivity, and a semiconductor obtained by the production method An object is to provide a polymer for lithography, a resist composition using the polymer for semiconductor lithography, and a method for producing a substrate on which a pattern is formed using the resist composition.

  In order to solve the above problems, a first aspect of the present invention is a polymerization step in which a monomer is polymerized in a polymerization solvent in the presence of a polymerization initiator to form a polymer, and the polymerization A method for producing a polymer, comprising a purification step in which the reaction solution obtained in the step is supplied into a poor solvent and reprecipitated, wherein in the polymerization step, part or all of the monomer is supplied dropwise. And the mass of the polymerization solvent used for the polymerization reaction is 2.0 times or less the mass of the whole monomer.

The second aspect of the present invention is the method for producing a polymer according to the first aspect, wherein at least one of the monomers is a monomer (a) having a polar group.
A third aspect of the present invention is the method for producing a polymer according to the first or second aspect, wherein at least one of the monomers is a monomer (b) having an acid leaving group. .
The fourth aspect of the present invention is the method for producing any one of the first to third polymers, wherein the monomer to be subjected to the polymerization reaction is a monomer selected from a methacrylate ester compound. .

A fifth aspect of the present invention is a polymer for semiconductor lithography obtained by any one of the first to fourth production methods.
A sixth aspect of the present invention is a resist composition containing the lithography polymer of the fifth aspect.
According to a seventh aspect of the present invention, there is provided a step of forming a resist film by applying the resist composition of the sixth aspect onto a work surface of a substrate, a step of exposing the resist film, and an exposed resist And a step of developing the film using a developing solution.

According to the method for producing a polymer of the present invention, a monomer can be converted to a polymer at a high reaction rate in the polymerization reaction without increasing the reaction time. The higher the monomer reaction rate, the lower the unreacted monomer component remaining in the polymer obtained in the polymerization step. Therefore, it is possible to obtain a polymer excellent in performance when used in a resist composition while maintaining productivity.
The polymer for semiconductor lithography of the present invention is obtained by converting a monomer into a polymer at a high reaction rate in a polymerization reaction, and when used in a resist composition because the monomer content remaining as an impurity is low. Excellent performance.
The resist composition of the present invention uses the polymer for semiconductor lithography of the present invention and is excellent in resist performance.
The method for producing a substrate of the present invention uses the resist composition of the present invention and is excellent in resist performance. Therefore, even a fine resist pattern can be stably formed with high accuracy. Accordingly, the substrate on which the pattern is formed can be manufactured with high accuracy and stability.

It is a graph which shows the result of an Example and a comparative example.

In this specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid. “(Meth) acrylate” means acrylate or methacrylate. “(Meth) acryloyloxy” means acryloyloxy or methacryloyloxy.
In the present specification, the “structural unit” of a polymer means a repeating unit derived from a monomer.

<Polymer>
The use of the polymer produced by the production method of the present invention is not particularly limited. For example, a polymer for semiconductor lithography used in the semiconductor lithography process (hereinafter sometimes simply referred to as a polymer for lithography) is preferable. As a polymer for lithography, a resist polymer used for forming a resist film, an antireflection film (TARC) formed on the upper layer of the resist film, or an antireflection film (BARC) formed on the lower layer of the resist film. Examples thereof include a polymer for antireflection film used for forming, a polymer for gap fill film used for forming a gap fill film, and a polymer for top coat film used for forming a top coat film.
Hereinafter, when the polymer is a resist polymer, a structural unit and a monomer corresponding to it will be described.

[Structural unit having polar group and monomer (a) corresponding thereto]
The polymer in the present invention preferably contains a structural unit (a) having a polar group. That is, at least one monomer used for polymer synthesis is preferably a monomer (a) having a polar group.
The “polar group” is a group having a polar functional group or a polar atomic group. Specific examples include a hydroxy group, a cyano group, an alkoxy group, a carboxy group, an amino group, a carbonyl group, and a fluorine atom. A group containing a sulfur atom, a group containing a lactone skeleton, a group containing an acetal structure, a group containing an ether bond, and the like.
Among these, the resist polymer applied to the pattern forming method that is exposed to light having a wavelength of 250 nm or less preferably has a structural unit having a lactone skeleton as the structural unit having a polar group, It is preferable to have a structural unit having a functional group.

(Constitutional unit having lactone skeleton and monomer corresponding thereto)
Examples of the lactone skeleton include a lactone skeleton having about 4 to 20 members. The lactone skeleton may be a monocycle having only a lactone ring, or an aliphatic or aromatic carbocyclic or heterocyclic ring may be condensed with the lactone ring.
In the case where the polymer contains a structural unit having a lactone skeleton, the content thereof is preferably 20 mol% or more, more preferably 25 mol% or more of all structural units (100 mol%) from the viewpoint of adhesion to a substrate or the like. Is more preferable. Moreover, from the point of a sensitivity and resolution, 60 mol% or less is preferable, 55 mol% or less is more preferable, and 50 mol% or less is further more preferable.

  As a monomer having a lactone skeleton, a (meth) acrylic acid ester having a substituted or unsubstituted δ-valerolactone ring, a substituted or unsubstituted γ-butyrolactone ring is used because of its excellent adhesion to a substrate or the like. Preferably, at least one selected from the group consisting of monomers having it is preferred, and monomers having an unsubstituted γ-butyrolactone ring are particularly preferred.

Specific examples of the monomer having a lactone skeleton include β- (meth) acryloyloxy-β-methyl-δ-valerolactone, 4,4-dimethyl-2-methylene-γ-butyrolactone, β- (meth) acryloyl. Oxy-γ-butyrolactone, β- (meth) acryloyloxy-β-methyl-γ-butyrolactone, α- (meth) acryloyloxy-γ-butyrolactone, 2- (1- (meth) acryloyloxy) ethyl-4-butanolide , (Meth) acrylic acid pantoyl lactone, 5- (meth) acryloyloxy-2,6-norbornanecarbolactone, 8-methacryloyloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decane- 3-one, 9-methacryloyloxy-4-oxa-tricyclo [5.2.1.0 ^{2, 6]} decan-3-one And the like. Examples of the monomer having a similar structure include methacryloyloxysuccinic anhydride.
Monomers having a lactone skeleton may be used alone or in combination of two or more.

[Structural unit having hydrophilic group and monomer corresponding thereto]
The “hydrophilic group” in the present specification is at least one of —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a methoxy group, a carboxy group, and an amino group.
Among these, it is preferable that the resist polymer applied to the pattern forming method exposed to light having a wavelength of 250 nm or less has a hydroxy group or a cyano group as a hydrophilic group.
The content of the structural unit having a hydrophilic group in the polymer is preferably from 5 to 30 mol%, more preferably from 10 to 25 mol%, of the total structural units (100 mol%) from the viewpoint of the resist pattern rectangularity. .

  Examples of the monomer having a hydrophilic group include a (meth) acrylic acid ester having a terminal hydroxy group; a derivative having a substituent such as an alkyl group, a hydroxy group, or a carboxy group on the hydrophilic group of the monomer; Monomers having a cyclic hydrocarbon group (for example, cyclohexyl (meth) acrylate, 1-isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, (meth) acrylic acid) Dicyclopentyl, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, etc.) having a hydrophilic group such as a hydroxy group or a carboxy group as a substituent; Can be mentioned.

Specific examples of the monomer having a hydrophilic group include (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy- (meth) acrylate. -Propyl, 4-hydroxybutyl (meth) acrylate, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate, etc. Is mentioned. From the viewpoint of adhesion to a substrate or the like, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate and the like are preferable.
The monomer which has a hydrophilic group may be used individually by 1 type, and may be used in combination of 2 or more type.

[Structural Unit Having Acid Leaving Group and Monomer (b) Corresponding to It]
In the case of a resist polymer, it is preferable to have a structural unit (b) having an acid-eliminable group in addition to the structural unit (a) having a polar group as described above. You may have. That is, it is preferable that at least one monomer used for the synthesis of the polymer is a monomer (b) having an acid leaving group.
The “acid leaving group” is a group having a bond that is cleaved by an acid, and a part or all of the acid leaving group is removed from the main chain of the polymer by cleavage of the bond.
In the resist composition, the polymer having the structural unit (b) having an acid-eliminable group reacts with the acid component to become soluble in an alkaline solution, and has an effect of enabling formation of a resist pattern.
The proportion of the structural unit having an acid leaving group is preferably 20 mol% or more, more preferably 25 mol% or more, out of all the structural units (100 mol%) constituting the polymer from the viewpoint of sensitivity and resolution. . Moreover, 60 mol% or less is preferable from the point of the adhesiveness to a board | substrate etc., 55 mol% or less is more preferable, and 50 mol% or less is further more preferable.

The monomer (b) having an acid leaving group may be a compound having an acid leaving group and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.
As a specific example of the monomer (b) having an acid leaving group, (meth) acrylic acid having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and having an acid leaving group Examples include esters. The alicyclic hydrocarbon group may be directly bonded to an oxygen atom constituting an ester bond of (meth) acrylic acid ester, or may be bonded via a linking group such as an alkylene group.
The (meth) acrylic acid ester has an alicyclic hydrocarbon group having 6 to 20 carbon atoms, and a tertiary carbon atom at the bonding site with the oxygen atom constituting the ester bond of the (meth) acrylic acid ester. A (meth) acrylic acid ester having an alicyclic group or an alicyclic hydrocarbon group having 6 to 20 carbon atoms and a -COOR group (R may have a substituent) on the alicyclic hydrocarbon group. (Meth) acrylic acid ester in which a tertiary hydrocarbon group, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group is bonded directly or via a linking group is included.

In particular, in the case of producing a resist composition that is applied to a pattern forming method that is exposed to light having a wavelength of 250 nm or less, as a preferred example of the monomer (b) having an acid leaving group, for example, 2-methyl 2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, 1- (1′-adamantyl) -1-methylethyl (meth) acrylate, 1-methylcyclohexyl (meth) acrylate, 1- Examples include ethylcyclohexyl (meth) acrylate, 1-methylcyclopentyl (meth) acrylate, 1-ethylcyclopentyl (meth) acrylate, isopropyl adamantyl (meth) acrylate, 1-ethylcyclooctyl (meth) acrylate, and the like.
As the monomer (b) having an acid leaving group, one type may be used alone, or two or more types may be used in combination.

Further, when the polymer is a polymer for an antireflection film, for example, it has a structural unit having a light-absorbing group, and in order to avoid mixing with a resist film, it can be cured by reacting with a curing agent or the like. It preferably contains a structural unit having a reactive functional group such as a group, an amide group, a hydroxyl group, or an epoxy group. That is, the monomer used for the synthesis of the polymer for an antireflection film contains at least one monomer having a light-absorbing group and at least one monomer having a reactive functional group. Is preferred.
The light-absorbing group is a group having high absorption performance with respect to light in a wavelength region where the photosensitive component in the resist composition is sensitive. Specific examples include an anthracene ring, naphthalene ring, benzene ring, quinoline ring. , A group having a ring structure (optionally substituted) such as a quinoxaline ring and a thiazole ring. In particular, when KrF laser light is used as irradiation light, an anthracene ring or an anthracene ring having an arbitrary substituent is preferable, and when ArF laser light is used, a benzene ring or a benzene having an arbitrary substituent A ring is preferred.
Examples of the optional substituent include a phenolic hydroxyl group, an alcoholic hydroxyl group, a carboxy group, a carbonyl group, an ester group, an amino group, and an amide group.
In particular, a polymer for an antireflection film having a protected or unprotected phenolic hydroxyl group as a light-absorbing group is preferable from the viewpoint of good developability and high resolution.
Examples of the monomer corresponding to the structural unit having the light absorbing group include benzyl (meth) acrylate and p-hydroxyphenyl (meth) acrylate.

The polymer for gap fill film has, for example, a reactive functional group that has an appropriate viscosity for flowing into a narrow gap and can be cured by reacting with a curing agent to avoid mixing with a resist film or an antireflection film. It is preferable to include a structural unit having
That is, it is preferable that the monomer used for the synthesis of the gap fill film polymer includes one or more monomers having a reactive functional group that can be cured by reacting with a curing agent or the like.
Specific examples of the gap fill film polymer include copolymers of hydroxystyrene and monomers such as styrene, alkyl (meth) acrylate, and hydroxyalkyl (meth) acrylate.

  Examples of the polymer for the topcoat film used in immersion lithography include a copolymer containing a structural unit having a carboxyl group, and a copolymer containing a structural unit having a fluorine-containing group substituted with a hydroxyl group. That is, it is preferable that the monomer used for the synthesis of the polymer for the topcoat film contains one or more monomers having a carboxyl group. Or it is preferable that 1 or more types of the monomer which has the fluorine-containing group which the hydroxyl group substituted is included.

<Method for producing polymer>
[Polymerization process]
The method for producing a polymer of the present invention includes a polymerization step in which a monomer is polymerized in a polymerization solvent in the presence of a polymerization initiator to form a polymer. That is, it is a solution polymerization method in which a monomer is radically polymerized using a polymerization initiator in the presence of a polymerization solvent.
In the method for producing a polymer of the present invention, the monomer used for the polymerization reaction is a methacrylic acid ester compound in that it can be suitably used as a lithography polymer without lowering the glass transition temperature of the polymer. It is preferable to use a monomer selected from A methacrylic acid ester compound is a compound represented by CH ₂ C (CH ₃ ) COOR (R is an optional substituent). Specifically, among the monomers listed above, it is preferable to select and use a methacrylic ester compound.
Dropping supply is used to supply the monomer and the polymerization initiator to the polymerization vessel. A polymerization method using a dropping supply (a dropping polymerization method) is preferable in that variations in average molecular weight and molecular weight distribution due to differences in production lots are small, and a reproducible polymer can be easily obtained.

In the dropping polymerization method, the inside of the polymerization vessel is heated to a predetermined polymerization temperature, and then the monomer and the polymerization initiator are dropped into the polymerization vessel independently or in any combination.
The monomer may be dropped only with the monomer, or may be dropped as a monomer solution in which the monomer is dissolved in a part of the polymerization solvent (hereinafter also referred to as “dropping solvent”). .
A polymerization solvent (hereinafter also referred to as “charged solvent”) may be charged into the polymerization vessel in advance, or the charged solvent may not be charged into the polymerization vessel in advance. When the charged solvent is not charged in the polymerization vessel in advance, the monomer or the polymerization initiator is dropped into the polymerization vessel in the absence of the charged solvent.

The polymerization initiator may be dissolved directly in the monomer, may be dissolved in the monomer solution, or may be dissolved only in the dropping solvent.
The monomer and the polymerization initiator may be dropped into the polymerization vessel after mixing in the same storage tank; they may be dropped into the polymerization container from each independent storage tank; They may be mixed immediately before the supply and dropped into the polymerization vessel.
One of the monomer and the polymerization initiator may be dropped first, and then the other may be dropped with a delay, or both may be dropped at the same timing.
The dropping rate may be constant until the end of dropping, or may be changed in multiple stages according to the consumption rate of the monomer or the polymerization initiator.
The dripping may be performed continuously or intermittently.
The polymerization temperature is preferably 50 to 150 ° C.

(Polymerization solvent)
Examples of the polymerization solvent include the following.
Ethers: chain ether (diethyl ether, propylene glycol monomethyl ether, etc.), cyclic ether (tetrahydrofuran (hereinafter referred to as “THF”), 1,4-dioxane, etc.) and the like.
Esters: methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, propylene glycol monomethyl ether acetate (hereinafter referred to as “PGMEA”), γ-butyrolactone, and the like.
Ketones: acetone, methyl ethyl ketone, methyl isobutyl ketone and the like.
Amides: N, N-dimethylacetamide, N, N-dimethylformamide and the like.
Sulfoxides: dimethyl sulfoxide and the like.
Aromatic hydrocarbons: benzene, toluene, xylene and the like.
Aliphatic hydrocarbon: hexane and the like.
Alicyclic hydrocarbons: cyclohexane and the like.
A polymerization solvent may be used individually by 1 type, and may use 2 or more types together.

(Polymerization initiator)
As the polymerization initiator, those that generate radicals efficiently by heat are preferable. Examples of the polymerization initiator include azo compounds (2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis [2- (2-imidazoline). -2-yl) propane], etc.), organic peroxides (2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane, di (4-tert-butylcyclohexyl) peroxydicarbonate, etc. Etc.).

In the method for producing a polymer of the present invention, the mass of the polymerization solvent used for the polymerization reaction is made 2.0 times or less of the mass of the whole monomer. In the case of the dropping polymerization method, the mass of the polymerization solvent provided for the polymerization reaction is the total mass of the dropping solvent and the charged solvent.
When the ratio of the mass of the polymerization solvent to the mass of the whole monomer (hereinafter sometimes referred to as “polymerization solvent / mass ratio of the whole monomer”) is 2.0 or less, the reaction temperature and reaction time are reduced. Even if it is not changed, the reaction rate of the monomer is effectively improved. That is, the unreacted monomer component remaining in the polymer can be effectively reduced while ensuring high productivity. When the mass ratio exceeds 2.0, the solid content concentration of the reaction solution is lowered, so that the polymerization reaction rate is slowed down, and the productivity is easily lowered.
Further, in order to more effectively improve the reaction rate of the whole monomer subjected to the polymerization reaction while ensuring productivity, the mass ratio of the polymerization solvent / the whole monomer is preferably 1.9 or less. .8 or less is more preferable, and 1.7 times or less is more preferable. Especially preferably, it is 1.6 or less, Most preferably, it is 1.5 or less.
The lower limit of the mass ratio of the polymerization solvent / whole monomer is not particularly limited, but is preferably 0.2 or more from the viewpoint of preventing the viscosity of the reaction solution from becoming too high and deteriorating handling properties. 4 or more is more preferable, and 0.6 or more is more preferable.

According to the method for producing a polymer of the present invention, a monomer subjected to a polymerization reaction can be converted into a polymer at a high reaction rate. Therefore, for example, even if a certain amount of monomer is removed in the purification step after the polymerization step and the yield of the polymer (including impurities) as a final product is made constant, the monomer reaction rate A higher polymer yields a polymer with a smaller amount of impurities (monomer). That is, it is possible to obtain a polymer that is superior in performance when used in a resist composition without reducing productivity.
In addition, as shown in the examples described later, the higher the monomer reaction rate and the smaller the amount of monomer remaining after the polymerization step, the smaller the amount of monomer remaining after the purification step.

<Method for quantifying monomer in reaction solution>
In the present invention, the reaction rate of the whole monomer is determined by quantifying the amount of monomer remaining in the reaction solution using the HPLC method, and the remaining monomer out of the total number of moles of monomers used for the reaction. The value is obtained by subtracting the number of moles, that is, the ratio of the number of moles of monomer consumed by the polymerization reaction.
The monomer is quantified under the following conditions.

(Monomer determination conditions)
0.5 g of the reaction solution is collected, diluted with acetonitrile, and made up to a total volume of 50 mL using a volumetric flask. The diluted solution was filtered through a 0.2 μm membrane filter, and the amount of unreacted monomer in the diluted solution was determined for each monomer using a high performance liquid chromatograph HPLC-8020 (product name) manufactured by Tosoh Corporation. Ask for.

  In this measurement, the separation column is manufactured by GL Sciences, using one Inertsil ODS-2 (trade name), the mobile phase is a water / acetonitrile gradient system, the flow rate is 0.8 mL / min, and the detector is manufactured by Tosoh Corporation. Measurement is performed with an ultraviolet / visible absorptiometer UV-8020 (trade name), a detection wavelength of 220 nm, a measurement temperature of 40 ° C., and an injection amount of 4 μL. As the separation column, Inertsil ODS-2 (trade name) having a silica gel particle diameter of 5 μm, a column inner diameter of 4.6 mm × column length of 450 mm is used. The gradient conditions of the mobile phase are as follows, with the liquid A being water and the liquid B being acetonitrile. In order to quantify the amount of unreacted monomer, three types of monomer solutions having different concentrations are used as standard solutions.

Measurement time 0 to 3 minutes: A liquid / B liquid = 90 vol% / 10 vol%.
Measurement time: 3 to 24 minutes: A liquid / B liquid = 90 volume% / 10 volume% to 50 volume% / 50 volume%.
Measurement time: 24 to 36.5 minutes: A liquid / B liquid = 50 volume% / 50 volume% to 0 volume% / 100 volume%.
Measurement time: 36.5 to 44 minutes: Liquid A / liquid B = 0 volume% / 100 volume%.

[Purification process]
The production method of the present invention includes a purification step in which the reaction solution obtained in the polymerization step is supplied into a poor solvent and reprecipitated.
Specifically, the polymer solution (reaction solution) obtained by the solution polymerization method is changed to 1,4-dioxane, acetone, THF, MEK, MIBK, γ-butyrolactone, PGMEA, PGME, ethyl lactate as necessary. After diluting to an appropriate solution viscosity with a diluting solvent, etc., the solution is dropped into a poor solvent to precipitate a polymer. This process is called reprecipitation and is very effective for removing unreacted monomers, polymerization initiators and the like remaining in the polymer solution. If the unreacted monomer remains as it is, the sensitivity decreases when used as a resist composition, so it is preferable to remove it as much as possible. The content of the unreacted monomer contained as an impurity in the polymer is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, further preferably 0.29% by mass or less, and 0.25 The mass% or less is most preferable.
As a poor solvent, what is necessary is just a solvent which the polymer to manufacture precipitates without melt | dissolving, A well-known thing can be used. For example, methanol, ethanol, isopropyl alcohol, water, hexane, heptane, diisopropyl ether, or a mixed solvent thereof can be used. In particular, methanol, isopropyl alcohol, diisopropyl ether, heptane, water, or a mixed solvent thereof is more preferable in that unreacted monomers, polymerization initiators, and the like used in polymers for semiconductor lithography can be efficiently removed. preferable.
Further, the amount of the poor solvent used is the same mass or more as the polymer solution (reaction solution) in order to further reduce the remaining unreacted monomer, preferably 3 times or more, more preferably 4 times or more, 5 More preferably double or more, and particularly preferably 6 times or more.

Thereafter, the precipitate is preferably filtered off to obtain a wet powder.
Further, after the wet powder is dispersed again in a poor solvent to obtain a polymer dispersion, an operation of filtering the polymer can be repeated. This process is called a restructuring process and is very effective for further reducing unreacted monomers, polymerization initiators and the like remaining in the polymer powder.
In terms of being able to obtain the polymer while maintaining high productivity, it is preferable to obtain the polymer only by the reprecipitation step without including the restructuring step.

The wet powder can be sufficiently dried to obtain a polymer.
In addition, after filtration, it may be used as a composition for semiconductor lithography by dissolving it in a suitable solvent without drying and as a composition for semiconductor lithography. After concentration to remove low-boiling compounds, the composition for semiconductor lithography is used. It may be used. At that time, additives such as a storage stabilizer may be appropriately added.

<Resist composition>
The resist composition of the present invention is obtained by dissolving a polymer for semiconductor lithography obtained by the production method of the present invention, preferably a resist polymer in a solvent. When the resist composition of the present invention is used as a chemically amplified resist composition, a photoacid generator is further dissolved.
(solvent)
Examples of the solvent for the resist composition include the same solvents as those used for the production of the polymer.

(Compound that generates acid upon irradiation with actinic rays or radiation)
The compound that generates an acid upon irradiation with actinic rays or radiation can be arbitrarily selected from those that can be used as a photoacid generator for a chemically amplified resist composition. A photo-acid generator may be used individually by 1 type, and may use 2 or more types together.
Examples of the photoacid generator include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinonediazide compounds, diazomethane compounds, and the like.
0.1-20 mass parts is preferable with respect to 100 mass parts of polymers, and, as for the quantity of a photo-acid generator, 0.5-10 mass parts is more preferable.

(Nitrogen-containing compounds)
The chemically amplified resist composition may contain a nitrogen-containing compound. By including the nitrogen-containing compound, the resist pattern shape, the stability over time, and the like are further improved. That is, the cross-sectional shape of the resist pattern becomes closer to a rectangle, and the resist film is irradiated with light, then baked (PEB), and then left for several hours before the next development process. Although it is a line, the occurrence of the deterioration of the cross-sectional shape of the resist pattern is further suppressed when left as such (timed).
The nitrogen-containing compound is preferably an amine, more preferably a secondary lower aliphatic amine or a tertiary lower aliphatic amine.
As for the quantity of a nitrogen-containing compound, 0.01-2 mass parts is preferable with respect to 100 mass parts of polymers.

(Organic carboxylic acid, phosphorus oxo acid or its derivative)
The chemically amplified resist composition may contain an organic carboxylic acid, an oxo acid of phosphorus, or a derivative thereof (hereinafter collectively referred to as an acid compound). By including an acid compound, it is possible to suppress deterioration in sensitivity due to the blending of the nitrogen-containing compound, and further improve the resist pattern shape, stability with time of leaving, and the like.
Examples of the organic carboxylic acid include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid.
Examples of phosphorus oxo acids or derivatives thereof include phosphoric acid or derivatives thereof, phosphonic acid or derivatives thereof, phosphinic acid or derivatives thereof, and the like.
The amount of the acid compound is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the polymer.

(Additive)
The resist composition of the present invention may contain various additives such as surfactants, other quenchers, sensitizers, antihalation agents, storage stabilizers, and antifoaming agents as necessary. Any additive can be used as long as it is known in the art. Further, the amount of these additives is not particularly limited, and may be determined as appropriate.

<Manufacturing method of substrate on which pattern is formed>
An example of the manufacturing method of the board | substrate with which the pattern was formed of this invention is demonstrated.
First, the resist composition of the present invention is applied by spin coating or the like to the surface of a substrate to be processed such as a silicon wafer on which a desired pattern is to be formed. And the resist film is formed on a board | substrate by drying the to-be-processed board | substrate with which this resist composition was apply | coated by baking process (prebaking) etc.

Next, the resist film is irradiated with light through a photomask to form a latent image (exposure). The irradiation light is preferably light having a wavelength of 250 nm or less, specifically, a KrF excimer laser, ArF excimer laser, F ₂ excimer laser, or EUV excimer laser is preferable, and an ArF excimer laser is particularly preferable. Moreover, you may irradiate an electron beam.
In addition, immersion in which light is irradiated with a high refractive index liquid such as pure water, perfluoro-2-butyltetrahydrofuran, or perfluorotrialkylamine interposed between the resist film and the final lens of the exposure apparatus. Exposure may be performed.

After the exposure, heat treatment is appropriately performed (post-exposure baking, PEB), an alkali developer is brought into contact with the resist film, and the exposed portion is dissolved in the developer and removed (development). Examples of the alkaline developer include known ones.
After development, the substrate is appropriately rinsed with pure water or the like. In this way, a resist pattern is formed on the substrate to be processed.

The substrate on which the resist pattern is formed is appropriately heat-treated (post-baked) to strengthen the resist and selectively etch the portion without the resist.
After the etching, the resist is removed with a release agent to obtain a substrate on which a pattern is formed.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. In addition, “part” in each example and comparative example means “part by mass” unless otherwise specified. The measurement method and evaluation method used the following methods.

[Measurement of weight average molecular weight]
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the polymer were determined in terms of polystyrene by gel permeation chromatography under the following conditions (GPC conditions).
(GPC conditions)
Equipment: Tosoh Corporation, Tosoh High Speed GPC Equipment HLC-8220GPC (trade name),
Separation column: manufactured by Showa Denko, Shodex GPC K-805L (trade name) connected in series,
Measurement temperature: 40 ° C.
Eluent: Tetrahydrofuran (THF)
Sample: A solution in which about 20 mg of a polymer is dissolved in 5 mL of THF and filtered through a 0.5 μm membrane filter.
Flow rate: 1 mL / min,
Injection volume: 0.1 mL,
Detector: differential refractometer.

Calibration curve I: About 20 mg of standard polystyrene was dissolved in 5 mL of THF, and the solution was filtered through a 0.5 μm membrane filter and injected into a separation column under the above conditions, and the relationship between elution time and molecular weight was determined. As the standard polystyrene, the following standard polystyrene manufactured by Tosoh Corporation (both trade names) were used.
F-80 (Mw = 706,000),
F-20 (Mw = 190,000),
F-4 (Mw = 37,900),
F-1 (Mw = 10,200),
A-2500 (Mw = 2,630),
A-500 (mixture of Mw = 682, 578, 474, 370, 260).

[Monomer determination]
(1) The amount of monomer remaining in the polymerization reaction solution was determined by the above-described <Method for quantifying monomers in reaction solution>.
(2) The monomer amount (monomer content as an impurity) contained in the polymer obtained after the purification step was determined by the following method.
0.1 g of a dry powder polymer obtained through the purification step and 4.0 g of acetonitrile were stirred and mixed for 1 hour. The obtained mixture was filtered through a 0.2 μm membrane filter, and the above <Method for quantifying monomer in reaction solution> was used using Tosoh Corporation high performance liquid chromatograph HPLC-8020 (product name). Similarly, the monomer content in the polymer was determined for each monomer.

[Evaluation of resist composition]
(Sensitivity and development contrast measurement)
The resist composition was spin-coated on a 6-inch silicon wafer and prebaked (PAB) at 120 ° C. for 60 seconds on a hot plate to form a thin film having a thickness of 300 nm. Using an ArF excimer laser exposure apparatus (VUVES-4500 manufactured by RISOTEC Japan), 18 shots of 10 mm × 10 mm ² were exposed while changing the exposure amount. Next, after post-baking (PEB) at 110 ° C. for 60 seconds, using a resist development analyzer (RDA-800 manufactured by RISOTEC Japan), development is performed with an aqueous 2.38 mass% tetramethylammonium hydroxide solution at 23 ° C. for 65 seconds. The change with time of the resist film thickness during development at each exposure amount was measured.

(analysis)
A curve plotting the logarithm of the exposure amount (mJ / cm ² ) and the residual film thickness ratio (hereinafter referred to as the residual film ratio) (%) when developed for 60 seconds with respect to the initial film thickness, based on the obtained data (Hereinafter, exposure dose-residual film rate curve) is prepared, and Eth sensitivity (required exposure amount for setting the remaining film rate to 0%, which represents sensitivity) and γ value (exposure dose-residual film rate curve). (Denoting the development contrast).
Eth sensitivity: exposure amount (mJ / cm ² ) at which the exposure amount-residual film rate curve intersects with a residual film rate of 0%
γ value: exposure - when the exposure amount of the residual film ratio of 50% residual film curve and ^{_{E 50 (mJ / cm 2)}} , the exposure amount - tangents at _{E 50} of residual film curve, residual film ratio 100 % of lines and Residual Film Ratio 0% line and intersects the exposure amount as E ₁₀₀ and E _0, respectively, were determined by the following equation.
γ = 1 / {log (E ₀ / E ₁₀₀ )}

  Of the monomers m1 to m6 used in the following examples and comparative examples, m1 and m6 are monomers having a lactone skeleton, m2 and m4 are monomers having an acid leaving group, and m3 and m5 are hydrophilic. It is a monomer having a group.

[Example 1]
In a flask equipped with a nitrogen inlet, a stirrer, a condenser, one dropping funnel, and a thermometer, 132.4 parts of PGMEA was placed under a nitrogen atmosphere. The flask was placed in a hot water bath, and the temperature of the hot water bath was raised to 80 ° C. while stirring the inside of the flask.
Thereafter, the following mixture 1 was dropped into the flask over 4 hours from the dropping funnel, and the temperature of 80 ° C. was further maintained for 3 hours.
Thereafter, the reaction solution was cooled to 25 ° C. to stop the polymerization reaction.
(Mixture 1)
68.00 parts of a monomer of the following formula (m1),
117.00 parts of a monomer of the following formula (m2),
23.60 parts of a monomer of the following formula (m3),
255.0 parts of PGMEA,
25.300 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, V601 (trade name), the same applies hereinafter).
The charge ratio (mol%) of each monomer is shown in Table 1.
In addition, the mass of the polymerization solvent when the mass of the whole monomer (in this example, the total mass of the monomers contained in the mixture 1) to be subjected to the polymerization reaction is 1 (in this example, in the flask in advance) Table 1 shows the ratio of PGMEA put into the total mass of PGMEA contained in the above mixture 1 (described in the table as “mass ratio of polymerization solvent / whole monomer”) (hereinafter the same). .

The amount of monomer remaining in the obtained reaction solution was quantified by the above method, and the reaction rate of the whole monomer was determined. The results are shown in Table 1 (hereinafter the same).
Furthermore, the purification process was performed by a method of reprecipitation by dropping the obtained reaction solution into a poor solvent. Specifically, 7.0 times the amount of the reaction solution as a poor solvent, a mixed solvent of methanol and water (methanol / water = 95/5 volume ratio) was used, and the reaction solution was added dropwise thereto while stirring the poor solvent. A white precipitate (polymer P1) was obtained. The precipitate was filtered off to obtain a polymer wet powder. The polymer powder was dried at 40 ° C. under reduced pressure for about 40 hours. The weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) of the polymer P1 thus obtained, and the monomer content in the polymer P1 (in the table, “monomer content after purification step” and Are described in Table 1 (hereinafter the same).

  100 parts of the polymer P1, 2 parts of triphenylsulfonium triflate as a photoacid generator, and PGMEA as a solvent are mixed so that the polymer concentration becomes 12.5% by mass to obtain a uniform solution. And filtered through a membrane filter having a pore size of 0.1 μm to obtain a resist composition. The obtained resist composition was evaluated by the above method. The results of Eth sensitivity and γ value are shown in Table 1 (hereinafter the same).

[Example 2]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 120.4 parts, and the mixture 1 was changed to the following mixture 2. The other processes were carried out in the same manner as in Example 1.
(Mixture 2)
68.00 parts of a monomer of the following formula (m1),
23.60 parts of a monomer of the following formula (m3),
98.00 parts of a monomer of the following formula (m4),
PGMEA 231.7 parts,
25.300 parts of dimethyl-2,2′-azobisisobutyrate.
The charge ratio (mol%) of each monomer is shown in Table 1.

  In the purification step of Example 1, re-precipitation was performed by changing the poor solvent to a mixed solvent of methanol and water (methanol / water = 90/10 volume ratio) in an amount 7.0 times that of the reaction solution. Otherwise, the polymer P2 was obtained in the same manner as in Example 1, and each evaluation was performed in the same manner as in Example 1.

[Example 3]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 130.5 parts, and the mixture 1 was changed to the following mixture 3. The other processes were carried out in the same manner as in Example 1.
(Mixture 3)
68.00 parts of a monomer of the following formula (m1),
117.00 parts of a monomer of the following formula (m2),
20.50 parts of a monomer of the following formula (m5),
251.2 parts of PGMEA,
Dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V601 (trade name)) 25.300 parts.
The charge ratio (mol%) of each monomer is shown in Table 1.

  The same operation as in the purification step of Example 1 was performed to obtain a polymer P3, and each evaluation was performed in the same manner as in Example 1.

[Example 4]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 108.0 parts, and the mixture 1 was changed to the following mixture 4. The other processes were carried out in the same manner as in Example 1.
(Mixture 4)
23.60 parts of a monomer of the following formula (m3),
98.00 parts of a monomer of the following formula (m4),
94.40 parts of a monomer of the following formula (m6),
PGMEA 216.0 parts,
11.500 parts of dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V601 (trade name)).
The charge ratio (mol%) of each monomer is shown in Table 1.

  180.0 parts of PGMEA was added to the resulting reaction solution, and the mixture was diluted by stirring until complete mixing. Thereafter, in the purification step of Example 1, a polymer P4 was obtained in the same manner as in Example 1 except that the poor solvent was changed to 6.0 times the amount of methanol in the diluted solution. Evaluation was performed.

[Example 5]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 104.3 parts, and the mixture 1 was changed to the following mixture 5. The other processes were carried out in the same manner as in Example 1. The monomer composition (monomer charge ratio, unit: mol%) and the mass of the entire monomer are the same as in Example 1.
(Mixture 5)
68.00 parts of a monomer of the following formula (m1),
117.00 parts of a monomer of the following formula (m2),
23.60 parts of a monomer of the following formula (m3),
208.6 parts of PGMEA,
11.500 parts of dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V601 (trade name)).

  To the obtained reaction solution, 173.8 parts of PGMEA was added, and the mixture was diluted by stirring until complete mixing. Thereafter, in the purification step of Example 1, a polymer P5 was obtained in the same manner as in Example 1 except that the poor solvent was changed to 6.0 times the amount of methanol in the diluted solution. Evaluation was performed.

[Example 6]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 94.8 parts, and the mixture 1 was changed to the following mixture 6. The other processes were carried out in the same manner as in Example 1. The monomer composition (mol%) and the mass of the whole monomer are the same as in Example 2.
(Mixture 6)
68.00 parts of a monomer of the following formula (m1),
23.60 parts of a monomer of the following formula (m3),
98.00 parts of a monomer of the following formula (m4),
189.6 parts of PGMEA,
11.500 parts of dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V601 (trade name)).

  To the obtained reaction solution, 158.0 parts of PGMEA was added, and the mixture was diluted by stirring until complete mixing. Thereafter, in the purification step of Example 1, except that the poor solvent was changed to a mixed solvent of methanol and water (methanol / water = 95/5 volume ratio) of 6.0 times the diluted solution. Similarly, a polymer P5 was obtained and evaluated in the same manner as in Example 1.

[Comparative Example 1]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 173.8 parts, and the mixture 1 was changed to the following mixture 7. The other processes were carried out in the same manner as in Example 1. The monomer composition (mol%) and the mass of the whole monomer are the same as in Example 1.
(Mixture 7)
68.00 parts of a monomer of the following formula (m1),
117.00 parts of a monomer of the following formula (m2),
23.60 parts of a monomer of the following formula (m3),
255.0 parts of PGMEA,
17.250 parts of dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V601 (trade name)).
The charge ratio (mol%) of each monomer is shown in Table 1.

  In the purification step of Example 1, re-precipitation was performed by changing the poor solvent to a mixed solvent of methanol and water (methanol / water = 80/20 volume ratio) 5.0 times the amount of the reaction solution. Other than that, a polymer P′1 was obtained in the same manner as in Example 1, and each evaluation was performed in the same manner as in Example 1.

[Comparative Example 2]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 143.5 parts, and the mixture 1 was changed to the following mixture 8. The other processes were carried out in the same manner as in Example 1. The monomer composition (mol%) and the mass of the whole monomer are the same as in Example 2.
(Mixture 8)
68.00 parts of a monomer of the following formula (m1),
23.60 parts of a monomer of the following formula (m3),
98.00 parts of a monomer of the following formula (m4),
PGMEA 352.1 parts,
13.800 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).

  In the purification step of Example 1, re-precipitation was carried out by changing the poor solvent to a mixed solvent of methanol and water (methanol / water = 70/30 volume ratio) of 5.0 times the amount of the reaction solution. Other than that, a polymer P′2 was obtained in the same manner as in Example 1, and each evaluation was performed in the same manner as in Example 1.

[Comparative Example 3]
In Example 1, the amount of PGMEA previously placed in the flask was changed to 360.0 parts, and the mixture 1 was changed to the following mixture 9. The other processes were carried out in the same manner as in Example 1. The monomer composition (mol%) and the mass of the whole monomer are the same as in Example 4.
(Mixture 9)
23.60 parts of a monomer of the following formula (m3),
98.00 parts of a monomer of the following formula (m4),
94.40 parts of a monomer of the following formula (m6),
PGMEA 504.0 parts,
10.350 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).

  In the purification step of Example 1, re-precipitation was carried out by changing the poor solvent to a mixed solvent of methanol and water (methanol / water = 70/30 volume ratio) of 5.0 times the amount of the reaction solution. Other than that, a polymer P′3 was obtained in the same manner as in Example 1, and each evaluation was performed in the same manner as in Example 1.

[Comparative Example 4]
In Comparative Example 3, the dropping time of the mixture 9 was changed from 4 hours to 6 hours. Other than that, a polymer P′4 was obtained in the same manner as in Comparative Example 3, and each evaluation was performed in the same manner as in Example 1.

As shown in the results of Table 1, Examples 1 to 6 and Comparative Examples 1 to 3 have the same polymerization temperature and polymerization time, but the polymerization solvent / total monomer mass ratio in the polymerization reaction is the same. In Examples 1-3 which are 1.86, the reaction rate of the whole monomer is as high as 96% or more. Moreover, in Examples 4-5 which made this mass ratio 1.50, the reaction rate of the whole monomer improved further with 97% or more.
On the other hand, in Comparative Examples 1 to 3 where the mass ratio is 2.30 to 4.00, the reaction rate of the entire monomer is as low as 86.5 to 91.2%.
In addition, Examples 1, 5 and Comparative Example 1, Examples 2, 6 and Comparative Example 2, Example 4 and Comparative Example 3 in which the monomer composition (mol%) and the mass of the whole monomer are the same are used. Even if each compares, the reaction rate of the whole monomer improves, so that the quantity of the polymerization solvent used for the polymerization reaction is small.

In Comparative Example 4, the mass ratio of the polymerization solvent / whole monomer in the polymerization reaction was 4.00. Therefore, the reaction rate of the whole monomer was significantly higher than that in Example 4 even though the dropping time was increased. Only low values could be reached.
Thus, in Example 4, compared with Comparative Examples 3 and 4, by setting the mass ratio of the polymerization solvent / total monomer to 2.0 or less, not only the reaction rate increased, but finally It can be seen that the reaction rate that can be reached has improved.

  Moreover, as Table 1 shows, compared with Comparative Examples 1-4, Examples 1-5 are remarkably small quantity of the monomer contained as an impurity in the polymer obtained after the refinement | purification process by reprecipitation. The sensitivity (Eth sensitivity) and development contrast (γ value) of the resist composition were remarkably improved.

FIG. 1 is a graph showing the results of Table 1. The horizontal axis represents the polymerization solvent / total monomer mass ratio in the polymerization reaction, and the left vertical axis represents the reaction rate of the entire monomer (unit:%). The right vertical axis represents the monomer content (unit: mass%) after the purification step.
As shown in this graph, when the mass ratio of the polymerization solvent / whole monomer in the polymerization reaction is 2.0 or less, the reaction rate of the whole monomer is remarkably increased, and the monomer content after the purification process is increased. The amount is significantly reduced.

Claims (7)

In a polymerization solvent, in the presence of a polymerization initiator, a polymerization process in which a monomer is polymerized to produce a polymer, and the reaction solution obtained in the polymerization process is supplied into a poor solvent for reprecipitation A method for producing a polymer, comprising a purification step,
In the polymerization step, a part or all of the monomer is supplied dropwise, and is used for the polymerization reaction. The weight of the polymerization solvent is 2.0 times or less the weight of the whole monomer, Manufacturing method of coalescence.   The method for producing a polymer according to claim 1, wherein at least one of the monomers is a monomer (a) having a polar group.   The method for producing a polymer according to claim 1 or 2, wherein at least one of the monomers is a monomer (b) having an acid leaving group.   The manufacturing method of the polymer as described in any one of Claims 1-3 whose monomer with which the said polymerization reaction is chosen is a monomer chosen from a methacrylic acid ester compound.   The polymer for semiconductor lithography obtained by the manufacturing method as described in any one of Claims 1-4.   A resist composition comprising the lithography polymer according to claim 5.   A step of applying the resist composition according to claim 6 on a work surface of a substrate to form a resist film, a step of exposing the resist film, and developing the exposed resist film using a developer. The manufacturing method of the board | substrate with which the pattern was formed including the process to perform.

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