JP5394119B2 - Method for producing polymer, method for producing resist composition, and method for producing substrate - Google Patents

Description

  The present invention relates to a method for producing a polymer, a resist polymer obtained by the production method, a resist composition using the resist polymer, and a substrate on which a pattern is formed using the resist composition. Regarding the 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 high-resolution resist composition used when forming a resist pattern using the 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 copolymer 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 Documents). 1, 2 etc.).

  By the way, a polymer of (meth) acrylic acid ester is generally polymerized by a radical polymerization method. In general, in a multi-component polymer having two or more types of monomers, the copolymerization reactivity ratio between the monomers is different, so the copolymer composition ratio of the polymer produced in the early stage of polymerization and the late stage of polymerization is different, and the resulting polymer is It has a composition distribution. Since a polymer having such a composition distribution tends to deteriorate the resist performance, studies have been made to control the composition distribution.

For example, in Patent Document 3, in order to obtain a resist having high substrate adhesion, the composition distribution is set such that the standard deviation of the copolymerization ratio of each copolymer component at any time during the polymerization reaction is 8 or less. The production of a narrow polymer is described. For this purpose, in the solution radical polymerization method or the emulsion radical polymerization method, the ratio of the low-reactivity monomer in the reaction solution is increased at the initial stage of polymerization, and a highly reactive monomer is added as the polymerization proceeds. A method is described.
Further, in Patent Document 4, in order to obtain a resist having a high resolution, the supply ratio of a relatively fast polymerization monomer and a slow monomer is changed in a pre-process and a post-process, and the copolymer composition distribution is changed. A method for obtaining narrow polymers is described.

JP 10-319595 A JP-A-10-274852 JP-A-57-120931 JP 2001-201856 A

  However, in these production methods, the control of the copolymer composition distribution may not be sufficient. If the composition ratio of the constituent units in the copolymer varies, the solubility in the solvent tends to be low, and it takes a long time to dissolve in the solvent when preparing the resist composition, or there is an insoluble content. Occurrence of this phenomenon may hinder the preparation of the resist composition, such as increasing the number of manufacturing steps. Further, the sensitivity of the resulting resist composition tends to be insufficient.

  The present invention has been made in view of the above circumstances, and has a small variation in composition ratio of structural units in a copolymer, good solubility in a solvent, and high sensitivity when used in a resist composition. , A method for producing a polymer, a resist polymer obtained by the production method, a resist composition using the resist polymer, and a method for producing a substrate on which a pattern is formed using the resist composition It aims to provide a method.

In order to solve the above-mentioned problems, the polymer production method of the present invention polymerizes two or more types of monomers α _{1 to} α _n (where n represents an integer of 2 or more) having a vinyl group . Then, a polymer (P) comprising the structural units α ′ _{1 to} α ′ _n (where α ′ _{1 to} α ′ _n represent structural units derived from the monomers α _{1 to} α _n , respectively) is produced. a method of, in advance in a reactor, wherein the step of charging a first solution containing the monomer alpha ₁ to? _n in the first composition, the in the reactor monomer alpha ₁ ~ a step of dropping a second solution containing α _n in a second composition; and a step of holding at the polymerization temperature after the step of dropping the second solution is completed. , The same as the design composition representing the target value of the content ratio of the structural units α ′ _{1 to} α ′ _n in the polymer (P) ,
When the design composition (unit: mol%) in the polymer (P) is α ′ ₁ : α ′ ₂ :...: Α ′ _n , the first composition (unit: mol%) is α ₁ : α. ₂ :...: Expressed by α _n and the factors obtained by the following methods (1) to (3) are expressed by F ₁ , F ₂ ,... F _n , α ₁ = α ′ ₁ / F ₁ , α ₂ = α ′ ₂ / F ₂ ,... α _n = α ′ _n / F _n .

(1) First, a monomer solution whose monomer composition is the same as the design composition α ′ ₁ : α ′ ₂ :...: Α ′ _n and a dropping solution containing a solvent are placed in a reactor containing only the solvent. The composition of the monomers α _{1 to} α _n remaining in the reactor when the elapsed time from the start of dropping is t ₁ , t ₂ , t ₃ . Mol%) M ₁ : M ₂ :...: M _n and constitutional units α ′ _{1 to} α ′ _n in the polymer produced between t ₁ and t ₂ , t ₂ to t ₃ , respectively. Ratio (unit: mol%) P ₁ : P ₂ :...: P _n is determined.
(2) the _{P 1: P 2: ...:} P n is, designed composition _{α '1: α' 2:} ...: α ' between the closest time zone _n from _{"t m} to _{t m + 1} (m is 1 or more Find an integer.)
(3) From the value of P ₁ : P ₂ :...: P _n in “between t _m and t _{m + 1} ” and the value of M ₁ : M ₂ :...: M _{n at} the elapsed time t _m , Factors F ₁ , F ₂ ,... F _n are obtained from the equations. F ₁ = P ₁ / M ₁ , F ₂ = P ₂ / M ₂ ,... F _n = P _n / M _n .

The ratio W ₀ (unit: total amount of monomers present in the reactor at the elapsed time t _m to the total amount of monomers initially contained in the dropping solution used in (1) above. Mass%), and a mass ratio of the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution (first solution: second solution). Is preferably W ₀ : (100−W ₀ ).

The present invention comprises a step of producing a resist polymer by the method for producing a polymer of the present invention, and a step of mixing the obtained resist polymer and a compound that generates an acid upon irradiation with actinic rays or radiation. A method for producing a resist composition is provided.
The present invention includes a step of producing a resist composition by the method for producing a resist composition of the present invention, a step of coating the obtained resist composition on a work surface of a substrate to form a resist film, Provided is a method for manufacturing a substrate on which a pattern is formed, which includes a step of exposing a resist film and a step of developing the exposed resist film using a developer.

  According to the method for producing a polymer of the present invention, the variation in the composition ratio of the structural units in the copolymer is small, the solubility in a solvent is good, and high sensitivity is obtained when used in a resist composition. A polymer is obtained.

The resist polymer of the present invention has a small variation in the composition ratio of the structural units in the copolymer, good solubility in a solvent, and high sensitivity when used in a resist composition. can get.
The resist composition of the present invention is a chemically amplified type and has excellent resolution, and since the solubility of the polymer is good, there are few insolubles in the composition and the sensitivity is excellent.
According to the substrate manufacturing method of the present invention, a substrate on which a pattern having few defects and excellent resolution can be stably manufactured with high productivity.

It is a graph which concerns on the calculation process of the factor in the Example of this invention. It is a graph which concerns on the Example which manufactures a polymer with the method of this invention. It is a graph which concerns on the calculation process of the factor in the Example of this invention. It is a graph which concerns on the Example which manufactures a polymer with the method of this invention. It is a graph which concerns on the calculation process of the factor in the Example of this invention. It is a graph which concerns on the Example which manufactures a polymer with the method of this invention. It is a graph concerning a comparative example. It is a graph concerning a comparative example.

  In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acryloyloxy” means acryloyloxy or methacryloyloxy.

In the present invention, two or more types of monomers α _{1 to} α _n (where n represents an integer of 2 or more) are polymerized to form structural units α ′ _{1 to} α ′ _n (where α ′ _i is This is a method for producing a polymer (P) comprising a structural unit derived from a monomer α _i , wherein i represents an integer of 2 or more and n or less, and n represents an integer of 2 or more.

<Polymer (P)>
The polymer (P) of the present invention comprises structural units α ′ _{1 to} α ′ _n . The upper limit of n is preferably 6 or less in that the effect of the present invention can be easily obtained. In particular, when the polymer (P) is a resist polymer, 5 or less is more preferable, and 4 or less is more preferable.
For example, when n = 3, the polymer (P) is a ternary polymer P (α ′ ₁ / α ′ ₂ / α ′ ₃ ) composed of structural units α ′ ₁ , α ′ ₂ and α ′ _3. When n = 4, the polymer (P) is a quaternary polymer P (α ′ ₁ / α ′ ₂ // consisting of structural units α ′ ₁ , α ′ ₂ , α ′ ₃ , α ′ _4. α ′ ₃ / α ′ ₄ ).

  The structural unit of the polymer (P) is not particularly limited, but when the polymer (P) is a resist polymer, it preferably has a structural unit having an acid leaving group. If necessary, it may have a known structural unit such as a structural unit having a lactone skeleton or a structural unit having a hydrophilic group.

<Constitutional unit / monomer>
As the monomer, monomers corresponding to the respective structural units α ′ _{1 to} α ′ _n of the polymer (P) to be obtained are used. The monomer is preferably a compound having a vinyl group, and is preferably a monomer that easily undergoes radical polymerization. In particular, (meth) acrylic acid ester is highly transparent to exposure light having a wavelength of 250 nm or less.
Hereinafter, when the polymer (P) is a resist polymer, a structural unit and a monomer corresponding to it will be described.

[Structural Unit / Monomer Having Acid Leaving Group]
The resist polymer preferably has 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.
When used as a resist composition, a polymer having a structural unit having an acid-eliminable group is soluble in an alkali by an acid, 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% by mole or more, more preferably 25% by mole or more among all the structural units 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.

Examples of the structural unit having an acid leaving group include a structural unit derived from a monomer having a known acid leaving group.
As the monomer having an acid leaving group, for example, a (meth) acryl having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and a group capable of leaving by the action of an acid. Acid ester etc. are mentioned. 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 the case of producing a resist composition applied to a pattern forming method in which exposure is performed with light having a wavelength of 250 nm or less, preferred examples of the monomer having an acid leaving group include, 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-ethylcyclohexyl (meth) Examples include acrylate, 1-methylcyclopentyl (meth) acrylate, 1-ethylcyclopentyl (meth) acrylate, and the like.
As the monomer having an acid leaving group, one type may be used alone, or two or more types may be used in combination.

[Constitutional unit / monomer having a lactone skeleton]
When applied to a pattern forming method in which exposure is performed with light having a wavelength of 250 nm or less, the resist polymer preferably further includes a structural unit having a lactone skeleton.
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.
The proportion of the structural unit having a lactone skeleton is preferably 20% by mole or more, more preferably 35% by mole or more, of all the structural units (100% by mole) from the viewpoint of adhesion to a substrate or the like. 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.

Examples of the structural unit having a lactone skeleton include structural units derived from a monomer having a lactone skeleton.
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-methacryloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decane-3 -One, 9-methacryloxy-4-oxatricyclo [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]
The resist polymer may further have a structural unit having a hydrophilic group. The “hydrophilic group” 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.
The proportion of the structural unit having a hydrophilic group is preferably from 5 to 30 mol%, more preferably from 10 to 25 mol%, out of all the structural units (100 mol%) from the viewpoint of the resist pattern rectangularity.

Examples of the structural unit having a hydrophilic group include a structural unit derived from a monomer having a hydrophilic group.
As the monomer having a hydrophilic group, for example, 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 (cyclohexyl (meth) acrylate, 1-isobornyl (meth) acrylate, adamantyl (meth) acrylate), tricyclodecanyl (meth) acrylate, dimethacrylate (meth) acrylate Cyclopentyl, 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.

<Polymerization method>
Examples of the polymerization method in the present invention include known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among these, the solution polymerization method is preferable in order not to reduce the light transmittance, in that the step of removing the monomer remaining after the completion of the polymerization reaction can be easily performed and the molecular weight of the polymer can be relatively lowered.
In the present invention, a dropping polymerization method is used in which the monomer and the polymerization initiator are supplied dropwise to the reactor.

In the present invention, a reactor is charged with a first solution containing monomers α _{1 to} α _n in a first composition in advance, and the reactor is heated to a predetermined polymerization temperature. A second solution containing the monomers α _{1 to} α _n in the second composition is dropped therein. The first solution and the second solution preferably contain a solvent.
The polymerization initiator may be contained in the second solution, or may be dropped into the reactor separately from the second solution.
The dropping speed may be constant until the dropping is completed, or may be changed in multiple stages according to the monomer consumption. The dripping may be performed continuously or intermittently.
The polymerization temperature is preferably 50 to 150 ° C.

Examples of the solvent include the following.
Ethers: linear ethers (eg, diethyl ether, propylene glycol monomethyl ether, etc.), cyclic ethers (eg, 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 solvent may be used individually by 1 type and may use 2 or more types together.

  As the polymerization initiator, those that generate radicals efficiently by heat are preferable. For example, an azo compound (2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] Etc.), organic peroxides (2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane, di (4-tert-butylcyclohexyl) peroxydicarbonate, etc.) and the like.

The content ratio (second composition) of the monomer in the second solution to be dropped is the same as the target value (design composition) of the content ratio of the structural units α ′ _{1 to} α ′ _n in the polymer (P). .
For example, the polymer (P) is a ternary polymer obtained by copolymerizing monomers x, y, and z, and the design composition (mol%, the same applies hereinafter) is x ′: y ′: When z ′, the second composition (mol%, the same shall apply hereinafter) x: y: z is the same as x ′: y ′: z ′.

The monomer content ratio (first composition) in the first solution charged in the reactor in advance is set to a composition obtained in advance by taking into account the design composition and the reactivity of each monomer used for polymerization. .
At this time, when the design composition (unit: mol%) in the polymer (P) is α ′ ₁ : α ′ ₂ :...: Α ′ _n , the first composition (unit: mol%) is α ₁ : α. ₂ :...: Expressed by α _n and the factors obtained by the following methods (1) to (3) are expressed by F ₁ , F ₂ ,... F _n , α ₁ = α ′ ₁ / F ₁ , α ₂ = α ′ ₂ / F ₂ ,... α _n = α ′ _n / F _n is preferable.
(1) First monomer composition is designed composition _{α '1: α' 2:} ...: α 'n dropwise a solution containing the monomer mixture 100 parts by weight of a solvent is the same as the reaction containing the solvent only The composition of the monomers α _{1 to} α _n remaining in the reactor when dropping at a constant dropping rate into the reactor and the elapsed time from the start of dropping is t ₁ , t ₂ , t ₃ . (Unit: mol%) M ₁ : M ₂ :...: M _n and constitutional unit α ′ ₁ in the polymer formed between t ₁ and t ₂ , between t ₂ and t ₃ ,. The ratio of α ′ _n (unit: mol%) P ₁ : P ₂ :...: P _n is determined.
(2) the _{P 1: P 2: ...:} P n is, designed composition _{α '1: α' 2:} ...: α ' between the closest time zone _n from _{"t m} to _{t m + 1} (m is 1 or more Find an integer.)
(3) From the value of P ₁ : P ₂ :...: P _n in “between t _m and t _{m + 1} ” and the value of M ₁ : M ₂ :...: M _{n at} the elapsed time t _m , Factors F ₁ , F ₂ ,... F _n are obtained from the equations. F ₁ = P ₁ / M ₁ , F ₂ = P ₂ / M ₂ ,... F _n = P _n / M _n .

More specifically, for example, the polymer (P) is a ternary polymer obtained by copolymerizing the monomers x, y, and z, and the design composition is x ′: y ′: When z ′, the first composition (mol%, the same shall apply hereinafter) x ₀ : y ₀ : z ₀ is obtained by using the factors Fx, Fy and Fz obtained by the following method, and x ₀ = x ′ / It is assumed that Fx, y ₀ = y ′ / Fy, z ₀ = z ′ / Fz.

[How to find factors Fx, Fy, Fz]
Hereinafter, the case where the polymer (P) is a ternary polymer will be described as an example, but the factor can be obtained in the same manner for a binary system or a quaternary system or more.
(1) First, a dropping solution containing a monomer mixture and a solvent whose monomer composition is the same as the design composition x ′: y ′: z ′ is dropped into the reactor at a constant dropping rate v. Only the solvent is put in the reactor in advance.
When the elapsed time from the start of dropping is t ₁ , t ₂ , t ₃ ..., The composition (mol%) Mx: My: Mz of the monomers x, y, z remaining in the reactor, between t ₁ to _{t 2,} the ratio of the structural unit in the polymer produced respectively between ... to from _{t 2} to _{t 3} (mol%) Px: Py: Request Pz.
(2) Find the time zone “between t _m and t _{m + 1} (m is an integer equal to or greater than 1)” where Px: Py: Pz is closest to the design composition x ′: y ′: z ′.
(3) From the value of Px: Py: Pz in “between t _m and t _{m + 1} ” and the value of Mx: My: Mz at the elapsed time t _m , the factors Fx, Fy, and Fz are calculated by the following equation. Ask.
Fx = Px / Mx, Fy = Py / My, Fz = Pz / Mz.
Factors Fx, Fy, and Fz are values that reflect the relative reactivity of each monomer, and change when the combination of monomers used for polymerization or the design composition changes.

[How to find the monomer content in the first solution and the second solution]
The content of the monomer in the first solution and the second solution is not particularly limited. As shown in the examples described later, the design composition can be obtained by dropping the second solution into the first solution. About the same desired polymer is produced. Therefore, for example, even if the polymerization reaction is stopped before the entire second solution is dropped, a desired polymer can be obtained.
The amount of the monomer to be contained in the first solution can be set according to, for example, a desired solid content concentration in a polymer solution obtained by forming a polymer in the first solution. For example, when the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution is 100% by mass, the monomers contained in the first solution 60 mass% or less is preferable, 50 mass% or less is more preferable, and 40 mass% or less is more preferable. The lower limit is not particularly limited, and is preferably set so as to satisfy the first composition in the range of more than 0% by mass.
What is necessary is just to set the total amount of the monomer contained in a 1st solution, and the sum total of the total amount of the monomer contained in a 2nd solution according to the quantity of the polymer (P) to obtain. .

In particular, the ratio of the total amount of monomers contained in the first solution and the ratio of the monomers contained in the second solution is determined by the method of (4) below using the step for obtaining the factor. Is preferred.
(4) The proportion of the total mass of monomers present in the reactor in the elapsed time t _m out of 100 mass% of the monomer mixture contained in the first dropping solution (W ₀ mass%) Ask for.
The mass ratio of the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution (first solution: second solution) is W ₀ : (100 preferably in a -W _0).

  It is preferable that the dropping rate when producing the polymer (P) is the same as the dropping rate v in the step of obtaining the factor. The dropping speed v is not particularly limited, and can be approximately the same as the dropping speed used in a normal dropping polymerization method.

As shown in the examples described later, if the first solution prepared in such a specific monomer composition (first composition) is previously charged in the reactor, the design composition in the reactor When the second solution prepared to have the same monomer composition (second composition) is dropped and reacted, a polymer almost the same as the design composition is generated immediately after the start of dropping.
Since the dropped monomer composition (second composition) is the same as the composition of the structural unit (design composition) in the polymer produced immediately after dropping, the monomer composition remaining in the reactor is always Constant (first composition). Accordingly, when the second solution is continuously dropped into the reactor, a steady state in which the polymer (P) as designed is continuously generated can be obtained.
The existence of the first composition capable of obtaining such a steady state has not been known prior to the present invention, and is a knowledge obtained for the first time by the present inventors.

The polymer produced in this manner has almost the same composition of the structural unit as the design composition and little variation. Therefore, the solubility in a solvent is good, and high sensitivity is obtained when it is used in a resist composition.
Further, the method for producing a polymer of the present invention has good reproducibility and can stably produce a high-quality polymer.
The polymer obtained by the production method of the present invention is particularly suitable as a resist polymer that requires high accuracy in the composition of the polymer.
The polymer of the present invention can be applied to applications other than resist applications, and since there is little variation in composition of constituent units in the polymer, improvement in solubility can be obtained and various performances can be expected.

<Resist composition>
The resist composition of the present invention is prepared by dissolving the resist polymer of the present invention in a solvent. Examples of the solvent include the same solvents as used for the production of the polymer.
When the resist composition of the present invention is a chemically amplified resist composition, a compound that generates an acid upon irradiation with actinic rays or radiation (hereinafter referred to as a photoacid generator) is further contained.

(Photoacid generator)
The photoacid generator can be arbitrarily selected from known photoacid generators in the 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, quinone diazide compounds, diazomethane compounds, and the like.
0.1-20 mass parts is preferable with respect to 100 mass parts of polymers, and, as for content of the photo-acid generator in a resist composition, 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. In a mass production line for semiconductor elements, the resist film is irradiated with light, then baked (PEB), and then left for several hours before the next development process. Occurrence of deterioration of the cross-sectional shape of the resist pattern due to is further suppressed.

The nitrogen-containing compound is preferably an amine, more preferably a secondary lower aliphatic amine or a tertiary lower aliphatic amine.
As for content of the nitrogen-containing compound in a resist composition, 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 content of the acid compound in the resist composition 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 on a processed surface of a substrate such as a silicon wafer on which a desired fine pattern is to be formed. And the resist film is formed on a board | substrate by drying the board | substrate with which this resist composition was apply | coated by baking process (prebaking) etc.

Next, the resist film is exposed through a photomask to form a latent image. The exposure light is preferably light having a wavelength of 250 nm or less. For example, KrF excimer laser, ArF excimer laser, F ₂ excimer laser and EUV light are preferable, and 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.

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 fine pattern is formed.

The resist polymer obtained by the production method of the present invention is excellent in solubility in a solvent because there is little variation in composition of constituent units. Therefore, dissolution in a solvent can be easily and satisfactorily performed when preparing a resist composition.
The resist composition of the present invention can form a highly sensitive resist film because there is little variation in the composition of constituent units in the resist polymer constituting the resist composition. Moreover, since the solubility of the resist polymer is good and the insoluble content in the resist composition is small, defects due to the insoluble content are less likely to occur in pattern formation.
Therefore, according to the substrate manufacturing method of the present invention, by using the resist composition of the present invention, a highly accurate fine resist pattern with few defects can be stably formed on the substrate. In addition, pattern formation by photolithography using an exposure light having a wavelength of 250 nm or less or lithography using an electron beam lithography such as ArF excimer laser (193 nm), which requires the use of a resist composition with high sensitivity and high resolution, is also required. It can be used suitably.
In the case of producing a resist composition used for photolithography using exposure light having a wavelength of 250 nm or less, a monomer is appropriately selected and used so that the polymer is transparent at the wavelength of the exposure light. Is preferred.

  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: 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).

(Quantification of monomer)
The amount of monomer remaining in the polymerization solution was determined by the following method.
0.5 g of the polymerization reaction solution in the reactor was collected, diluted with acetonitrile, and the total volume was adjusted to 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. Asked.

  In this measurement, a separation column is manufactured by GL Sciences, and one Inertsil ODS-2 (trade name) is used. 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. Ultraviolet / visible absorptiometer UV-8020 (trade name), detection wavelength 220 nm, measurement temperature 40 ° C., injection amount 4 μL. The separation column Inertsil ODS-2 (trade name) used was a silica gel particle diameter of 5 μm, a column inner diameter of 4.6 mm × column length of 450 mm. The gradient conditions of the mobile phase were 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 were 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%.

(Evaluation of polymer solubility)
20 parts of the polymer and 80 parts of PGMEA were mixed and stirred while maintaining at 25 ° C., and complete dissolution was judged visually, and the time until complete dissolution was measured.

(Evaluation of resist composition sensitivity)
The resist composition was spin-coated on a 6-inch silicon wafer and pre-baked (PAB) at 120 ° C. for 60 seconds on a hot plate to form a resist film having a thickness of 300 nm. Using an ArF excimer laser exposure apparatus (product name: VUVES-4500, manufactured by RISOTEC JAPAN), 18 shots having an area of 10 mm × 10 mm were exposed while changing the exposure amount. Next, after post-baking (PEB) at 110 ° C. for 60 seconds, 2.38% tetrahydroxide at 23.5 ° C. using a resist development analyzer (product name: RDA-806, manufactured by RISOTEC JAPAN). Developed with aqueous methylammonium solution for 65 seconds. For each exposure amount of the resist film, the change with time in the resist film thickness during development was measured.

Based on the data of change in resist film thickness over time, the logarithm of the exposure amount (unit: mJ / cm ² ) and the ratio of the remaining film thickness at the time of development for 30 seconds with respect to the initial film thickness (unit:%). , Hereinafter referred to as the residual film ratio) was plotted, and an exposure amount-residual film ratio curve was prepared. Based on this curve, the value of the necessary exposure amount (Eth) for obtaining a remaining film rate of 0% was determined. That is, the exposure amount (mJ / cm ² ) at the point where the exposure amount-residual film rate curve intersects a straight line with a residual film rate of 0% was determined as Eth. The value of Eth represents sensitivity, and the smaller the value, the higher the sensitivity.

<Example 1>
[Calculation of factors Fx, Fy, Fz]
In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, 67.8 parts of ethyl lactate 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 flask.
Thereafter, a dropping solution (total amount: 205.725 g) containing the following monomer mixture, solvent, and polymerization initiator was prepared, and this was dropped into the flask at a constant dropping rate over 4 hours from the dropping funnel. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.
28.56 parts of monomer m-1 of the following formula (m-1),
32.93 parts of monomer m-2 of the following formula (m-2),
19.82 parts of monomer m-3 of the following formula (m-3),
122.0 parts ethyl lactate,
2.415 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).
Table 1 shows the charging ratio of each monomer in the dropping solution (second composition, unit: mol%). The design composition of the polymer produced in this example is m-1: m-2: m-3 = 40: 40: 20 (mol%).

  After 0.5, 1, 2, 3, 4, 5, 6, 7 hours from the start of dropping of the dropping solution, 0.5 g of the polymerization reaction solution in the flask was sampled, and monomers m-1 to m-3 were sampled. Quantification of each was performed. The results are shown in Table 2.

  The residual monomer mass in the reactor of Table 2 was converted into the molar fraction (corresponding to Mx: My: Mz), respectively, using the monomer molecular weight. The results are shown in Table 3.

  Further, by subtracting the mass of the monomer remaining in the reactor obtained in Table 2 from the mass of the monomer supplied to the reactor at a constant rate for 4 hours, the supplied monomer Of these, the mass of those converted into polymers was calculated. The results are shown in Table 4.

Based on the results in Table 4, the mass (difference data) of the polymer produced at each sampling interval was calculated. The mass of the produced (converted) polymer obtained here is the weight of the polymer produced during the time from the dropping (reaction time) from t ₁ to t ₂ , from t ₂ to t _3. Applicable. The results are shown in Table 5.

The weight (difference data) of the polymer produced | generated at each obtained sampling interval was converted into the mole fraction, respectively, and it was set as the polymer composition ratio (mol%). This polymer composition ratio represents the composition ratio of structural units in the polymer, and corresponds to Px: Py: Pz. The results are shown in Table 6.
FIG. 1 is a graph showing the results of Table 6. The horizontal axis in FIG. 1 indicates the reaction time on the end side of the reaction time zone. That is, in FIG. 1, the data when the reaction time on the horizontal axis is 3 hours corresponds to the data when the reaction time zone is 2 to 3 hours in Table 6 (the same applies hereinafter).

From the results of Table 6 and FIG. 1, the time zone “between t _m and t _{m + 1} ” where Px: Py: Pz (polymer composition ratio) is closest to the design composition 40:40:20 is 2 to 2. The reaction time zone is 3 hours.
Therefore, from the value of Px: Py: Pz when the reaction time is 2 to 3 hours (Table 6) and the value of Mx: My: Mz when the elapsed time is 2 hours (Table 3), Fx = Px / Mx, Factors Fx, Fy, and Fz were obtained from Fy = Py / My and Fz = Pz / Mz.
As a result, Fx = 1.27, Fy = 0.76, and Fz = 1.22.
Table 7 below shows the results of determining factors for other reaction time zones for reference.

The first composition x ₀ : y ₀ : z ₀ is obtained using 40:40:20 of the design composition (x ′: y ′: z ′) and the values of the factors Fx, Fy, and Fz obtained above. It was.
x ₀ = 40 / 1.27 = 31.3 mole%.
y ₀ = 40 / 0.76 = 52.4 mole%.
z ₀ = 20 / 1.22 = 16.3 mole%.

[Calculation of monomer content in first solution and second solution]
Assuming that the monomer mixture (total 81.31 parts) contained in the first dropping solution is 100% by mass, the total mass of monomers present in the reactor at 2 hours elapsed (from Table 2, 14.4). 13 parts) occupies 17.4% (W ₀ ).
Accordingly, the mass ratio (first solution: second solution) between the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution is 17.4. : 82.6.

[Production of polymer]
A polymer is produced using the first composition (x ₀ : y ₀ : z ₀ ) obtained above and the value (mass ratio) of the monomer content in the first solution and the second solution. did.
In the process in which the factors Fx, Fy, and Fz were calculated, the monomers m-1 to m-3 were charged into the flask with the first composition (x ₀ : y ₀ : z ₀ ) before the start of dropping. Others were performed in the same procedure as the factor calculation step.
Mass ratio of the total amount of monomers present in the flask (first solution) before the start of dropping and the total amount of monomers contained in the dropping solution (second solution) (first solution: second solution) The solution was 17.4: 82.6.

That is, in a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, 67.8 parts of ethyl lactate, 3.87 parts of monomer m-1 and a single amount under a nitrogen atmosphere 7.46 parts of body m-2 and 2.80 parts of monomer m-3 were added. 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 flask.
Thereafter, a dropping solution (total amount: 191.605 g) containing the following monomer mixture, solvent, and polymerization initiator was prepared, and this was dropped into the flask at a constant dropping rate over 4 hours from the dropping funnel. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.
23.60 parts (40 mol%) of monomer m-1
27.21 parts (40 mol%) of monomer m-2,
16.38 parts (20 mol%) of monomer m-3,
122.0 parts ethyl lactate,
2.415 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)).
Table 8 shows the charging ratio of each monomer. The design composition of the polymer produced in this example is m-1: m-2: m-3 = 40: 40: 20 (mol%).

The polymer composition ratio (mol%) in the polymer produced at each sampling interval was determined in the same procedure as in the factor calculation step. The results are shown in Table 9.
FIG. 2 is a graph showing the results of Table 9.

Comparing the results of FIG. 1 and FIG. 2, when only the solvent was put in the flask before dropping (FIG. 1), the composition ratio of the polymer produced immediately after the start of dropping was greatly deviated from the design composition. In addition, the polymer composition varies greatly depending on the elapsed time (reaction time).
On the other hand, when a predetermined amount of monomer with a predetermined composition is added to the solvent in the flask before the dropping (FIG. 2), the composition of the structural unit is almost the same as the design composition immediately after the dropping. A coalescence was obtained, the dispersion of the composition ratio was improved, and a polymer having an overall composition ratio closer to the design composition was obtained. In particular, the composition ratio of the polymer obtained by the reaction time of 4 hours in which the dropping was continued is small from the design composition.

[Purification of polymer]
After the reaction time of 7 hours had elapsed, the polymerization reaction solution in the flask was dropped into the white solution while stirring about 10 times the amount of methanol and water mixed solvent (methanol / water = 80/20 volume ratio). A precipitate (Polymer P1) was obtained. The precipitate was filtered off and again poured into a mixed solvent of methanol and water in the same amount as above (methanol / water = 90/10 volume ratio), and the precipitate was washed with stirring. And the precipitate after washing | cleaning was separated by filtration, and polymer wet powder (160g) was obtained. 10 g of the polymer wet powder was dried at 40 ° C. under reduced pressure for about 40 hours. About the obtained polymer P1, Mw and Mw / Mn were calculated | required and solubility evaluation was performed by said method. The results are shown in Table 23.

[Production of resist composition]
The remainder of the polymer wet powder was put into 88000 g of PGMEA and completely dissolved, and then passed through a nylon filter having a pore size of 0.04 μm (P-NYLON N66FILTER 0.04M (trade name) manufactured by Nippon Pole Co., Ltd.). And filtered.
The obtained filtrate was heated under reduced pressure to distill off methanol and water, and further, PGMEA was distilled off to obtain a polymer P1 solution having a polymer concentration of 25% by mass. During the distillation, the maximum degree of vacuum was 0.7 kPa, the maximum solution temperature was 65 ° C., and the distillation time was 8 hours.

  400 parts of the obtained polymer P1 solution, 2 parts of triphenylsulfonium triflate as a photoacid generator, and PGMEA as a solvent were mixed so that the polymer concentration was 12.5% by mass. After preparing a uniform solution, the solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain a resist composition. The sensitivity of the obtained resist composition was evaluated by the above method. The results are shown in Table 23.

<Example 2>
[Calculation of factors Fx, Fy, Fz]
The factors Fx, Fy, and Fz were calculated in the same manner as in Example 1 except that the monomer and solvent were changed in Example 1. The composition of the dropping solution is as follows. In the flask, 70.6 parts of PGMEA was put before dropping.
26.83 parts of monomer m-4 of the following formula (m-4),
40.25 parts of monomer m-5 of the following formula (m-5),
17.63 parts of monomer m-6 of the following formula (m-6),
127.1 parts of PGMEA,
8.802 parts of dimethyl-2,2′-azobisisobutyrate (the above V601 (trade name)). The design composition of the polymer produced in this example and the monomer composition (second composition) in the dropping solution are m-4: m-5: m-6 = 40: 40: 20 (mol%). .

Table 10 shows the residual monomers m-4 to m-6 present in the flask after 0.5, 1, 2, 3, 4, 5, 6, 7 hours from the start of dropping of the dropping solution. It is a quantity (unit: part), and Table 11 is the result of converting this into a molar fraction (corresponding to Mx: My: Mz).
Also, during the mass but was converted into a polymer of the monomers fed in the same manner as in Example 1 to calculate the elapsed time from dropping on the basis of this (reaction time) from t ₁ to t ₂ The polymer composition ratio Px: Py: Pz in the polymer produced between t ₂ and t ₃ was calculated. The results are shown in Table 12 and FIG.

From the results of Table 12 and FIG. 3, a reaction time zone of 1 to 2 hours was adopted as a time zone in which Px: Py: Pz (polymer composition ratio) was closest to the design composition of 40:40:20.
From the value of Px: Py: Pz when the reaction time zone is 1 to 2 hours (Table 12) and the value of Mx: My: Mz when the elapsed time is 1 hour (Table 11), Fx = Px / Mx, Fy = Factors Fx, Fy, and Fz were obtained from Py / My and Fz = Pz / Mz.
As a result, Fx = 0.80, Fy = 1.10, and Fz = 1.42.

The first composition x ₀ : y ₀ : z ₀ was determined using 40:40:20 of the design composition (x ′: y ′: z ′) and the values of the factors Fx, Fy, and Fz.
x ₀ = 40 / 0.80 = 49.8 mol%.
y ₀ = 40 / 1.10 = 36.2 mole%.
z ₀ = 20 / 1.42 = 14.0 mole%.

[Calculation of monomer content in first solution and second solution]
Assuming that the monomer mixture (total 84.71 parts) contained in the first dropping solution is 100% by mass, the total mass of monomers present in the reactor at an elapsed time of 1 hour (from Table 10, 6. 40 parts) (W ₀ ) is 7.6%.
Accordingly, the mass ratio of the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution (first solution: second solution) is 7.6. : 92.4.

[Production of polymer]
Using the first composition (x ₀ : y ₀ : z ₀ ) obtained above and the value (mass ratio) of the monomer content in the first solution and the second solution, Example 1 A polymer was produced in the same manner.
In the flask, 70.6 parts of PGMEA and a monomer mixture having the following composition (total of 6.4 parts) were placed before dropping.
2.60 parts (49.8 mol%) of monomer m-4,
2.84 parts (36.2 mol%) of monomer m-5,
0.96 part (14.0 mol%) of monomer m-6.
The composition of the dropping solution is as follows.
Monomer m-4 24.80 parts (40 mol%),
37.21 parts (40 mol%) of monomer m-5,
16.30 parts (20 mol%) of monomer m-6,
122.0 parts PGMEA,
8.802 parts of dimethyl-2,2′-azobisisobutyrate (the above V601 (trade name)).

The polymer composition ratio (mol%) in the polymer produced at each sampling interval was determined in the same procedure as the factor calculation step. The results are shown in Table 13.
FIG. 4 is a graph showing the results of Table 13.

  Comparing the results of FIG. 3 and FIG. 4, FIG. 3 shows that the composition ratio of the polymer produced immediately after the start of dripping greatly deviates from the design composition, whereas in FIG. A polymer having a composition almost the same as the design composition was obtained, and variation in the composition ratio was improved, and a polymer having an overall composition ratio closer to the design composition was obtained. In particular, the composition ratio of the polymer obtained by the reaction time of 4 hours in which the dropping was continued is small from the design composition.

[Purification of polymer]
A mixed solvent of methanol and water (methanol / water = 80/20 volume ratio) and (methanol / water = 90/10 volume ratio) used in the purification process of the polymer of Example 1 were mixed with methanol and water, respectively. Polymerization reaction in the flask after a reaction time of 7 hours in the same manner as in Example 1 except that the solvent (methanol / water = 90/10 volume ratio) and (methanol / water = 95/5 volume ratio) were changed. From the solution, a polymer P2 was obtained. Table 23 shows the results of Mw, Mw / Mn, and solubility evaluation of the polymer P2.
[Production of resist composition]
In the same manner as in Example 1, a resist composition containing the polymer P2 was prepared, and the sensitivity was evaluated. The results are shown in Table 23.

<Example 3>
[Calculation of factors Fx, Fy, Fz]
The factors Fx, Fy, and Fz were calculated in the same manner as in Example 1 except that the monomer and solvent were changed in Example 1. The composition of the dropping solution is as follows. In the flask, 70.3 parts of PGMEA was put before dropping.
34.00 parts of monomer m-1 of the following formula (m-1),
31.44 parts of monomer m-7 of the following formula (m-7),
18.88 parts of monomer m-3 of the following formula (m-3),
126.5 parts PGMEA,
9.108 parts of dimethyl-2,2′-azobisisobutyrate (the above V601 (trade name)). The design composition of the polymer produced in this example and the monomer composition (second composition) in the dropping solution are m-1: m-7: m-3 = 50: 30: 20 (mol%). .

Table 14 shows the remaining monomer m-1, 7, 3 present in the flask after 0.5, 1, 2, 3, 4, 5, 6, 7 hours from the start of dropping of the dropping solution. The amount (unit: part) is shown in Table 15. Table 15 shows the result of conversion into a molar fraction (corresponding to Mx: My: Mz).
Also, during the mass but was converted into a polymer of the monomers fed in the same manner as in Example 1 to calculate the elapsed time from dropping on the basis of this (reaction time) from t ₁ to t ₂ The polymer composition ratio Px: Py: Pz in the polymer produced between t ₂ and t ₃ was calculated. The results are shown in Table 16 and FIG.

From the results of Table 16 and FIG. 5, a reaction time zone of 1 to 2 hours was adopted as a time zone in which Px: Py: Pz (polymer composition ratio) was closest to the design composition 50:30:20.
From the value of Px: Py: Pz when the reaction time zone is 1-2 hours (Table 16) and the value of Mx: My: Mz when the elapsed time is 1 hour (Table 15), Fx = Px / Mx, Fy = Factors Fx, Fy, and Fz were obtained from Py / My and Fz = Pz / Mz.
As a result, Fx = 1.17, Fy = 0.78, and Fz = 1.08.

Using the design composition (x ′: y ′: z ′) of 50:30:20 and the values of the factors Fx, Fy, and Fz, the first composition x ₀ : y ₀ : z ₀ was obtained.
x ₀ = 50 / 1.17 = 42.9 mole%.
y ₀ = 30 / 0.78 = 38.6 mole%.
z ₀ = 20 / 1.08 = 18.6 mol%.

[Calculation of monomer content in first solution and second solution]
Assuming that the monomer mixture (total 84.32 parts) contained in the first dropping solution is 100% by mass, the total mass of monomers present in the reactor at an elapsed time of 1 hour (from Table 14, 7. 83 parts) (W ₀ ) is 9.3%.
Thus, the mass ratio (first solution: second solution) of the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution is 9.3. : 90.7.

[Production of polymer]
Using the first composition (x ₀ : y ₀ : z ₀ ) obtained above and the value (mass ratio) of the monomer content in the first solution and the second solution, Example 1 A polymer was produced in the same manner.
Before dropping, 70.3 parts of PGMEA and a monomer mixture having the following composition (total 7.83 parts) were placed in the flask.
2.62 parts (42.9 mol%) of monomer m-1;
3.63 parts (38.6 mol%) of monomer m-7,
1.58 parts (18.6 mol%) of monomer m-3.
The composition of the dropping solution is as follows.
30.84 parts (50 mol%) of monomer m-1;
28.52 parts (30 mol%) of monomer m-7,
17.13 parts (20 mol%) of monomer m-3,
126.5 parts PGMEA,
9.108 parts of dimethyl-2,2′-azobisisobutyrate (the above V601 (trade name)).

The polymer composition ratio (mol%) in the polymer produced at each sampling interval was determined in the same procedure as the factor calculation step. The results are shown in Table 17.
FIG. 6 is a graph showing the results of Table 17.

  Comparing the results of FIG. 5 and FIG. 6, FIG. 5 shows that the composition ratio of the polymer produced immediately after the start of dripping is significantly different from the design composition, whereas in FIG. A polymer having a composition almost the same as the design composition was obtained, and variation in the composition ratio was improved, and a polymer having an overall composition ratio closer to the design composition was obtained. In particular, the composition ratio of the polymer obtained by the reaction time of 4 hours in which the dropping was continued is small from the design composition.

[Purification of polymer]
In the same manner as in Example 2, a polymer P3 was obtained from the polymerization reaction solution in the flask after 7 hours of reaction time. Table 23 shows the results of Mw, Mw / Mn, and solubility evaluation of the polymer P3.
[Production of resist composition]
In the same manner as in Example 1, a resist composition containing the polymer P3 was prepared, and the sensitivity was evaluated. The results are shown in Table 23.

<Comparative Example 1>
In the calculation process of factors Fx, Fy, and Fz of Example 1, the comparative polymer 1 was prepared in the same manner as in the purification process of the polymer of Example 1, using the polymerization reaction solution in the flask obtained with a reaction time of 7 hours. Obtained. About the obtained comparative polymer 1, Mw and Mw / Mn were calculated | required similarly to Example 1, and solubility evaluation was performed.
Moreover, using the comparative polymer 1, a resist composition was prepared in the same manner as in Example 1, and the sensitivity was evaluated. The results are shown in Table 23.

<Comparative example 2>
In the calculation process of the factors Fx, Fy, and Fz in Example 2, the comparative polymer 2 was prepared in the same manner as in the polymer purification process in Example 2, using the polymerization reaction solution in the flask obtained with a reaction time of 7 hours. Obtained. About the obtained comparative polymer 2, it carried out similarly to Example 2, calculated | required Mw and Mw / Mn, and performed solubility evaluation.
Further, using the comparative polymer 2, a resist composition was prepared in the same manner as in Example 2, and the sensitivity was evaluated. The results are shown in Table 23.

<Comparative Example 3>
In the calculation process of the factors Fx, Fy, and Fz in Example 3, using the polymerization reaction solution in the flask obtained with a reaction time of 7 hours, the comparative polymer 3 was prepared in the same manner as in the polymer purification process in Example 3. Obtained. About the obtained comparative polymer 3, it carried out similarly to Example 3, calculated | required Mw and Mw / Mn, and performed solubility evaluation.
Further, using the comparative polymer 3, a resist composition was prepared in the same manner as in Example 3, and the sensitivity was evaluated. The results are shown in Table 23.

<Comparative Example 4>
In the following Comparative Examples 4 to 6, without using the above factor values, a part of the monomer mixture according to the designed composition was charged into a reactor, and the rest was used as a dropping solution to produce a polymer. Therefore, the composition of the monomer mixture in the dropping solution is different from the designed composition. In the monomer mixture charged into the reactor, the content ratio of the monomer having a relatively low reaction rate was set higher than the design composition, and the content ratio of the monomer having a relatively high reaction rate was set lower than the design composition.

In this example, the same monomers m-1, m-2, and m-3 as in Example 1 were used as the monomers.
First, in a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, 105.2 parts of ethyl lactate, 1.56 parts of monomer m-1 and a single amount in a nitrogen atmosphere 18.03 parts of body m-2 and 1.09 parts of monomer m-3 were added. 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 flask.
Thereafter, a dropping solution (total amount: 173.625 g) containing the following monomer mixture, solvent, and polymerization initiator was prepared, and this was dropped into the flask at a constant dropping rate over 4 hours from the dropping funnel. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.
29.72 parts (49.4 mol%) of monomer m-1;
18.03 parts (26.0 mol%) of monomer m-2,
20.63 parts (24.7 mol%) of monomer m-3,
102.6 parts of ethyl lactate,
2.645 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)).
The charge ratio of each monomer is shown in Table 18. The design composition of the polymer produced in this example is m-1: m-2: m-3 = 40: 40: 20 (mol%). Moreover, the ratio of the monomer in the total of the monomer charged in the reactor and the monomer contained in the dropping solution was also m-1: m-2: m-3 = 40: 40: 20 (mol %).

The polymer composition ratio (mol%) in the polymer produced at each sampling interval was determined in the same procedure as the factor calculation step of Example 1. The results are shown in Table 19.
FIG. 7 is a graph showing the results of Table 19.

  Comparing the result of FIG. 7 of this example with the result of FIG. 2 of Example 1, in this example, the composition ratio of the polymer produced immediately after the start of dripping was significantly different from the design composition, and the elapsed time (reaction time) The composition of the polymer produced by

In this example, a comparative polymer 4 was obtained in the same manner as in the polymer purification step of Example 1 using the polymerization reaction solution in the flask obtained after the reaction time of 7 hours had elapsed. About the obtained comparative polymer 4, it carried out similarly to Example 1, calculated | required Mw and Mw / Mn, and performed solubility evaluation.
Further, using the comparative polymer 4, a resist composition was prepared in the same manner as in Example 1, and the sensitivity was evaluated. The results are shown in Table 23.

<Comparative Example 5>
In this example, the same monomers m-4, m-5, and m-6 as in Example 2 were used as the monomers.
In Comparative Example 4, the solvent and the monomer charged into the flask were 95.1 parts of PGMEA, 13.42 parts of monomer m-4, 2.01 parts of monomer m-5, monomer m The value was changed to 0.88 part of -6. Moreover, the composition of the dropping solution was changed to the following. The others were dropped in the same manner as in Comparative Example 4.
13.42 parts (26.0 mol%) of monomer m-4,
38.24 parts (49.4 mol%) of monomer m-5,
16.75 parts (24.7 mol%) of monomer m-6,
102.6 parts of PGMEA,
8.802 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)).
The charge ratio of each monomer is shown in Table 20. The design composition of the polymer produced in this example is m-4: m-5: m-6 = 40: 40: 20 (mol%). Moreover, the ratio of the monomer in the total of the monomer charged in the reactor and the monomer contained in the dropping solution was m-4: m-5: m-6 = 40: 40: 20 (moles). %).

In this example, when 5 minutes had elapsed after the start of dropping, the solution in the flask became cloudy and a polymer was deposited. That is, a uniform polymerization reaction field could not be maintained. Further, the precipitated polymer adhered to the stirrer and the polymerization reaction could not be continued.
Only the solubility evaluation for the polymer attached to the stirrer was performed. The results are shown in Table 23.

<Comparative Example 6>
In this example, the same monomers m-1, m-7, and m-3 as in Example 3 were used as the monomers.
In Comparative Example 4, the solvent and monomer charged into the flask were PGMEA 111.9 parts, monomer m-1 1.56 parts, monomer m-7 18.08 parts, monomer m -3 to 1.09 parts. Moreover, the composition of the dropping solution was changed to the following. The others were dropped in the same manner as in Comparative Example 4.
37.54 parts (58.5 mol%) of monomer m-1;
Monomer m-7, 18.08 parts (18.3 mol%),
20.63 parts (23.2 mol%) of monomer m-3,
114.4 parts PGMEA,
10.474 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)).
Table 21 shows the charging ratio of each monomer. The design composition of the polymer produced in this example is m-1: m-7: m-3 = 50: 30: 20 (mol%). Moreover, the ratio of the monomer in the total of the monomer charged into the reactor and the monomer contained in the dropping solution was also m−1: m−7: m−3 = 50: 30: 20 (mol %).

In the same manner as in Comparative Example 4, the polymer composition ratio (mol%) in the polymer produced at each sampling interval was determined. The results are shown in Table 22.
FIG. 8 is a graph showing the results of Table 22.

  Comparing the results of FIG. 8 of this example with those of FIG. 6 of Example 3, in this example, the composition ratio of the polymer produced immediately after the start of dripping was significantly different from the design composition, and the elapsed time (reaction time) The composition of the polymer produced by

  In this example, using the polymerization reaction solution in the flask obtained after the reaction time of 7 hours had passed, a comparative polymer 6 and a resist composition using the same were obtained in the same manner as in Comparative Example 4, and Mw, Mw / Mn was determined and solubility evaluation and sensitivity evaluation were performed. The results are shown in Table 23.

From the results shown in Table 23, the polymers obtained in Examples 1, 2, and 3 have significantly improved solubility as compared with the polymers obtained in Comparative Examples 1, 2, and 3, respectively, and a resist composition was obtained. Improved sensitivity.
In Comparative Examples 4 to 6, the monomer mixture was previously charged in the reactor in consideration of the reactivity of the monomer, but the above factor was not used, and the monomer mixture in the dropping solution was used. The composition of is not the same as the design composition. The polymers obtained in Comparative Examples 4, 5, and 6 were much less soluble than the polymers obtained in Examples 1, 2, and 3, respectively.

Claims (4)

Two or more kinds of monomers α _{1 to} α _n having vinyl groups (where n represents an integer of 2 or more) are polymerized to form structural units α ′ _{1 to} α ′ _n (where α ′ ₁ ˜α ′ _n represents a structural unit derived from each of the monomers α _{1 to} α _n ), and a method for producing a polymer (P) comprising:
Advance in the reactor, said a step of charging a first solution containing the monomer alpha ₁ to? _N in the first composition, the reactor in the monomer alpha ₁ to? _N of the second A step of dropping the second solution contained in the composition, and a step of holding at the polymerization temperature after the step of dropping the second solution is completed;
The second composition is the same as the design composition representing the target value of the content ratio of the structural units α ′ _{1 to} α ′ _n in the polymer (P),
When the design composition (unit: mol%) in the polymer (P) is α ′ ₁ : α ′ ₂ :...: Α ′ _n , the first composition (unit: mol%) is α ₁ : α. ₂ :...: Expressed by α _n and the factors obtained by the following methods (1) to (3) are expressed by F ₁ , F ₂ ,... F _n , α ₁ = α ′ ₁ / F ₁ , α ₂ = _{α '2 / F 2, ...} α n = α' is a n / _{F n,} the production method of the polymer.
(1) First , a monomer solution whose monomer composition is the same as the design composition α ′ ₁ : α ′ ₂ :...: Α ′ _n and a dropping solution containing a solvent are placed in a reactor containing only the solvent. The composition of the monomers α _{1 to} α _n remaining in the reactor when the elapsed time from the start of dropping is t ₁ , t ₂ , t ₃ . Mol%) M ₁ : M ₂ :...: M _n and constitutional units α ′ _{1 to} α ′ _n in the polymer produced between t ₁ and t ₂ , t ₂ to t ₃ , respectively. Ratio (unit: mol%) P ₁ : P ₂ :...: P _n is determined.
(2) the _{P 1: P 2: ...:} P n is, designed composition _{α '1: α' 2:} ...: α ' between the closest time zone _n from _{"t m} to _{t m + 1} (m is 1 or more Find an integer.)
(3) From the value of P ₁ : P ₂ :...: P _n in “between t _m and t _{m + 1} ” and the value of M ₁ : M ₂ :...: M _{n at} the elapsed time t _m , Factors F ₁ , F ₂ ,... F _n are obtained from the equations . F ₁ = P ₁ / M ₁ , F ₂ = P ₂ / M ₂ ,... F _n = P _n / M _n . The ratio W ₀ (unit: total amount of monomers present in the reactor at the elapsed time t _m to the total amount of monomers initially contained in the dropping solution used in (1) above. Mass%), and a mass ratio of the total amount of monomers contained in the first solution and the total amount of monomers contained in the second solution (first solution: second solution). the _{W 0: (100-W 0} ) to method for producing a polymer according to claim 1, wherein. A step of producing a resist polymer by the method for producing a polymer according to claim 1 or 2,
The manufacturing method of a resist composition which has the process of mixing the obtained polymer for resists, and the compound which generate | occur | produces an acid by irradiation of actinic light or a radiation. A step of producing a resist composition by the method for producing a resist composition according to claim 3;
A step of applying the obtained resist composition onto 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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