JP6100986B2 - Method for producing polymer, method for producing resist composition, and method for producing substrate on which pattern is formed - Google Patents

Description

  The present invention relates to a polymer, a resist composition containing the polymer, and a method for producing a substrate on which a pattern is formed, and more particularly to a resist composition suitable for microfabrication using excimer laser and electron beam lithography.

In recent years, in the field of microfabrication in the manufacture of semiconductor elements and liquid crystal elements, miniaturization has rapidly progressed due to advances in lithography technology. As a method for miniaturization, generally, the wavelength of irradiation light is shortened. Specifically, from conventional ultraviolet rays typified by g-line (wavelength: 438 nm) and i-line (wavelength: 365 nm). The irradiation light is changing to a shorter wavelength DUV (Deep Ultra Violet).
At present, KrF excimer laser (wavelength: 248 nm) lithography technology has been introduced to the market, and ArF excimer laser (wavelength: 193 nm) lithography technology and F ₂ excimer laser (wavelength: 157 nm) lithography technology for further shortening of wavelength have been studied. Has been. Recently, these immersion lithography techniques have also been studied. Also, as a different type of lithography technology, electron beam lithography technology has been energetically studied.

As a high-resolution resist using such short-wavelength irradiation light or electron beam, a “chemically amplified resist” containing a photoacid generator has been proposed, and improvement and development of this chemically amplified resist are currently underway. It has been.
For example, as a chemically amplified resist resin used in ArF excimer laser lithography, an acrylic resin that is transparent with respect to light having a wavelength of 193 nm has attracted attention. As such an acrylic resin, for example, a polymer of a (meth) acrylic acid ester having an alicyclic skeleton such as an adamantane skeleton in an ester portion and a (meth) acrylic acid ester polymer having a lactone skeleton in an ester portion is disclosed in Patent Literature. 1 and Patent Document 2 and the like.

  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. Such a polymer in which the copolymer composition ratio is not controlled has been studied to control the composition distribution in order to reduce the resist performance.

For example, in Patent Document 3, in order to obtain a highly sensitive resist, a polymer having a standard deviation of the copolymerization ratio of each copolymer component at an arbitrary time during the polymerization reaction of 8 or less, that is, a narrow composition distribution. It is described that a polymer is used as a resist resin.
However, the resist described in Patent Document 3 is not sufficient in terms of solubility in a developer, resolution, and depth of focus (DOF).
JP 10-319595 A JP-A-10-274852 JP-A-57-120931

  An object of the present invention is to provide a resist composition having uniform solubility in a developer, high sensitivity, high resolution, and excellent depth of focus (DOF), and is suitable for such a resist composition. The purpose is to provide coalescence. It is another object of the present invention to provide a method for manufacturing a substrate on which a pattern is formed which is less likely to cause disconnection or a defect in a circuit and has a high yield.

The first gist of the present invention is a method for producing a resist polymer containing 5 to 60 mol% of a structural unit derived from a monomer having an acid leaving group, wherein the polymer is the polymer. When the polymer (P _H ) having a molecular weight higher than the mass average molecular weight (Mw (P)) is fractionated by gel permeation chromatography, the polymer (P) satisfying the following formula (1) So that the acid-eliminating group-containing monomer (F) corresponding to 3 to 10 mol% of the total amount of monomers having acid-eliminating groups (F + G) In the method for producing a polymer, a monomer (G) having a functional group and a mixture containing other monomers are dropped and polymerized.

P [α _A ] / P _H [α _A ] ≦ 0.990 (1)
(In the formula (1), P [α _A ] is the ratio of the number of structural units derived from monomers having acid-leaving groups to the number of structural units derived from all monomers in the polymer (P). P _H [α _A ] represents the ratio of the number of structural units derived from the monomer having an acid-eliminable group to the number of structural units derived from all monomers of the polymer (P _H ). )
According to a second aspect of the present invention, in the method for producing a polymer according to the first aspect, the solution containing the monomer (F) having an acid-eliminable group is a unit other than the monomer (F). It is in the manufacturing method of a polymer which does not contain a monomer.

The third aspect of the invention is a method of manufacture of the polymer of the steps of producing a polymer in the production process, a resist composition comprising the step of producing a resist composition using the resulting polymer.
The fourth gist of the present invention includes a step of producing a resist composition by the method for producing a resist composition, a step of applying the obtained resist composition onto a substrate to be processed, and light having a wavelength of 250 nm or less. It exists in the manufacturing method of the board | substrate with which the pattern containing the process to expose and the process developed using a developing solution was formed.

In the polymer of the present invention, the composition distribution is controlled so as to satisfy the above formula (1) and the constituent unit derived from the monomer having an acid leaving group is 5 to 60 mol% or less. When used in the composition, the solubility in the developer is uniform, the sensitivity is high, the resolution is high, and the depth of focus (DOF) is excellent. Therefore, the polymer of this invention is suitable as a polymer for resists, and is suitable as a polymer for fine processing used in manufacture of a semiconductor element and a liquid crystal element.

Moreover, the resist composition using the polymer of the present invention can be suitably used for DUV excimer laser lithography, these immersion lithography and electron beam lithography, particularly ArF excimer laser lithography, and this immersion lithography.
Moreover, the substrate on which a highly accurate fine pattern is formed can be manufactured with a high yield by the substrate manufacturing method of the present invention.

It is the chromatogram obtained by the polar analysis of polymer S1-S3. It is the chromatogram obtained by the polar analysis of the polymer P1. It is the chromatogram obtained by the polar analysis of polymer P'1.

The polymer of the present invention will be described.
The polymer of this invention contains 5-60 mol% of structural units derived from the monomer having an acid leaving group. Here, the “acid-leaving group” refers to a group that decomposes or leaves by the action of an acid. Therefore, the structural unit derived from the monomer having an acid-eliminable group is a component whose solubility in alkali is increased by an acid. When the polymer of the present invention is used for a resist composition, a resist pattern can be formed. Has the effect of.
When used in a resist composition, the structural unit derived from a monomer having an acid leaving group needs to be 5 mol% or more in the structural unit derived from all monomers of the polymer from the viewpoint of sensitivity and resolution. Yes, 20 mol% or more is preferable, and 25 mol% or more is more preferable. Further, from the viewpoint of adhesion to the substrate surface or the like, 60 mol% or less is necessary in the structural unit derived from all monomers of the polymer, preferably 55 mol% or less, and more preferably 50 mol% or less.
When the structural unit derived from the monomer having an acid leaving group exceeds 60 mol%, the performance is insufficient in terms of the rectangularity of the pattern and the depth of focus (DOF), and the unit having the acid leaving group is not sufficient. When the structural unit derived from the monomer is less than 5 mol%, the performance is insufficient in terms of sensitivity and resolution.

Furthermore, the polymer (P) of the present invention is obtained by fractionating a polymer (P _H ) having a molecular weight larger than the mass average molecular weight (Mw (P)) of the polymer by gel permeation chromatography. In addition, it is necessary to satisfy the following formula (1).
P [α _A ] / P _H [α _A ] ≦ 0.990 (1)
In the formula (1), P [α _A ] represents the ratio of the number of structural units derived from monomers having acid-leaving groups in the structural units derived from all monomers in the polymer (P), P _H [α _A ] represents the ratio of the number of structural units derived from the monomer having an acid-eliminable group in the structural units derived from all monomers of the polymer (P _H ).
As defined by the formula (1), the value obtained by dividing the P [α _A ] by the P _H [α _A ] is 0.990 or less. P) means that the polymer (P _H ) having a molecular weight larger than the mass average molecular weight (Mw (P)) contains a large number of structural units derived from the monomer having an acid-eliminable group. .

In general, since a polymer has a molecular weight distribution, when used in a resist composition, the solubility in a developer becomes non-uniform. This is because the solubility in the developer is (i) the molecular weight of the polymer and (ii) the structural unit derived from the monomer having an acid-eliminable group in the polymer chain (the solubility in alkali is increased by the acid. This is because it depends on the amount of the component.
As for (i), in the polymer chain having the same amount of the structural unit derived from the monomer having an acid-eliminable group, the higher the molecular weight, the slower the dissolution rate in the developer, and vice versa. The dissolution rate in the liquid increases.
As for (ii), in a polymer chain having the same molecular weight, if the amount of the structural unit derived from the monomer having an acid-eliminable group is large, the dissolution rate in the developer is increased, and conversely, the acid is eliminated. If the amount of the structural unit derived from the monomer having a functional group is small, the dissolution rate in the developer is slow.

The polymer (P) of the present invention contains a large number of acid-eliminable groups in the molecular chain having a molecular weight larger than its mass average molecular weight Mw (P). Therefore, the slow dissolution rate due to the large molecular weight (the effect of (i) above) is compensated by the high dissolution rate due to the large amount of the acid leaving group (the effect of (ii) above), As a result, the solubility of the entire polymer in the developer becomes uniform.
From the viewpoint of solubility in a resist solvent, a value obtained by dividing P [αA] by PH [αA], that is, P [αA] / PH [αA] is 0.2. The above is preferable.
The polymer (P) of the present invention contains 5 to 60 mol% of a structural unit derived from a monomer having an acid leaving group, and the relationship between the molecular weight distribution and the composition distribution is as shown in the formula (1). Therefore, when the polymer of the present invention is used in a chemically amplified resist composition, the difference in the dissolution rate in the developer due to the difference in molecular weight of each polymer chain is represented by the composition of the structural unit having an acid leaving group. This is compensated by the difference in distribution, and the solubility in the developer becomes uniform. As a result, a chemically amplified resist composition having uniform solubility in a developer, high sensitivity, high resolution, and excellent depth of focus (DOF) can be obtained.

In the present invention, the mass average molecular weight (Mw (P)) of the polymer (P) is a polystyrene conversion value determined by gel permeation chromatography under the following conditions (hereinafter referred to as GPC condition I). is there.
<GPC condition I>
Apparatus: Tosoh Corporation make, Tosoh high-speed GPC apparatus HLC-8220GPC (trade name).
Separation column: manufactured by Showa Denko, three Shodex GPC K-805L (trade name) connected in series.
Measurement temperature: 40 ° C.
Eluent: Tetrahydrofuran (hereinafter referred to as THF).
Sample: A solution obtained by dissolving 20 mg of the polymer (P) in 5 ml of THF and filtering through a 0.5 μm membrane filter.
Flow rate: 1 ml / min.
Injection volume: 0.1 ml.
Detector: differential refractometer.

Calibration curve I: Dissolve 20 mg of standard polystyrene in 5 ml of THF, and inject it into a separation column under the above conditions using a solution filtered through a 0.5 μm membrane filter, and determine the relationship between elution time and molecular weight. As standard polystyrene, the following standard polystyrenes manufactured by Tosoh (both are trade names) are 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).

In the present invention, the polymer (P _H ) having a molecular weight larger than the mass average molecular weight (Mw (P)) is separated from the polymer (P) by the following method (procedures (1) to (4)). It is taken.
(1) The mass average molecular weight (Mw (P)) of the polymer is determined according to the GPC condition I.
(2) The GPC condition is changed to the following GPC condition II, and a calibration curve II (relation between elution time and molecular weight) is determined using standard polystyrene.
(3) In the calibration curve II, the elution time T at which the molecular weight is Mw (P) determined in the above (1) is determined.
(4) In the following GPC conditions II, was injected a solution of the polymer in the preparative column, fractionated the components have been eluted before the elution time T obtained in (3) as P _H.

<GPC condition II>
Apparatus: Tosoh Corporation make, Tosoh high-speed GPC apparatus HLC-8220GPC (trade name).
Preparative column: Showa Denko, Shodex GPC K-2005 (trade name) connected in series.
Measurement temperature: 40 ° C.
Eluent: Tetrahydrofuran (hereinafter referred to as THF).
Sample: A solution obtained by dissolving 120 mg of the polymer (P) in 5 ml of THF and filtering through a 0.5 μm membrane filter.
Flow rate: 4 ml / min.
Injection volume: 1 ml.
Detector: differential refractometer.

Calibration curve II: Using a solution obtained by dissolving 120 mg of standard polystyrene in 5 ml of THF and filtering through a 0.5 μm membrane filter, the solution is injected into a preparative column under the above conditions, and the relationship between elution time and molecular weight is determined. As standard polystyrene, the following standard polystyrenes manufactured by Tosoh (both are trade names) are 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)

Here, for the formula (1), when the polymer (P) has structural units derived from three types of monomers, that is, the polymer (P) is a ternary polymer P (α ₁ / α ₂ / The case of α ₃ ) will be described as an example.
For example, when α ₁ is a structural unit derived from a monomer having an acid leaving group, and α ₂ and α ₃ are structural units derived from a monomer having no acid leaving group, the formula ( P [α _A ] in 1) represents the total number of structural units derived from monomers in the polymer (P) (<< α ₁ >> + << α ₂ >> + << α ₃ >>) in the polymer (P). This is the ratio of the number of constituent units α ₁ << α ₁ >>.
P [α _A ] = << α ₁ >> / (<< α ₁ >> + << α ₂ >> + << α ₃ >>) (2)
In formula (2), << α ₁ >> represents the number of structural units α _{1 in} the polymer (P), << α ₂ >> represents the number of structural units α ₂ in the polymer (P), and << α ₃ >> represents the number of structural units α ₃ in the polymer (P).

Further, for example, when α ₁ and α ₂ are structural units derived from a monomer having an acid leaving group, and α ₃ is a structural unit derived from a monomer having no acid leaving group, P [α _A ] in the formula (1) is the structural unit α in the polymer (P) with respect to the total number of structural units (<< α ₁ >> + << α ₂ >> + << α ₃ >>) in the polymer (P). _It is a fraction of the total amount of the number of ₁ << α ₁ >> and the number of structural units α ₂ << α ₂ >>.
P [α _A ] = (<< α ₁ >> + << α ₂ >>) / (<< α ₁ >> + << α ₂ >> + << α ₃ >>) (3)
In the formula (3), << α ₁ >> to << α ₃ >> have the same meaning as the formula (2).
The case where the polymer (P) is a ternary polymer P (α ₁ / α ₂ / α ₃ ) having structural units derived from three types of monomers has been described as an example, but the polymer (P) The same applies to the case where has a structural unit derived from two or four or more monomers.

When the ratio of the number of structural units derived from monomers having an acid-eliminable group in the structural units derived from all monomers in the polymer can be determined by ¹ H-NMR measurement, ¹ H- Obtained by NMR measurement, and if it cannot be obtained by ¹ H-NMR measurement due to proton peak overlap or the like, it is obtained by ¹³ C-NMR measurement.
In addition, the ratio of the number of the structural units derived from the monomer which can be calculated | required by NMR measurement is synonymous with the mol% of each structural unit.

The measurement of ¹ H-NMR was carried out by using a GSX-400 type FT-NMR (trade name) manufactured by JEOL Ltd. and a 5% by mass solution of the polymer (P) of the present invention (deuterated chloroform solution). Alternatively, a deuterated dimethyl sulfoxide solution) is put into a test tube having a diameter of 5 mmφ, and the measurement is carried out 64 times in an observation frequency of 400 MHz and a single pulse mode. The measurement temperature is 40 ° C. when deuterated chloroform is used as the solvent, and 60 ° C. when deuterated dimethyl sulfoxide is used as the solvent.
^In the case of ¹³ C-NMR measurement, 20% by mass of a deuterated dimethyl sulfoxide solution of the polymer (P) of the present invention using UNITY-INOVA FT-NMR (trade name) manufactured by Varian Technologies, Inc. The sample is put in a 5 mmφ test tube, and the integration is performed 50000 times by the proton complete decoupling method in which the measurement temperature is 60 ° C., the observation frequency is 125 MHz, and the nuclear overhauser effect (NOE) is removed.

  Next, a structural unit derived from a monomer having an acid leaving group will be described.

  When the structural unit (B) derived from the monomer having an acid leaving group has a lactone skeleton, the substrate adhesion tends to be good. Moreover, when the structural unit (B) derived from the monomer having an acid leaving group has a hydrophilic group, it tends to have more excellent sensitivity.

  The structural unit (B) derived from the monomer having an acid-eliminable group is not particularly limited. However, from the viewpoint of high dry etching resistance required for a resist, the following formulas (3-1-1) and ( It is preferably at least one selected from the group consisting of 3-2-1), (3-4-1), (3-8-1), and (3-12-1).

In formula (3-1-1), R ³¹ represents a hydrogen atom or a methyl group, R ¹ represents an alkyl group having 1 to 3 carbon atoms, and X ¹ represents a linear or branched alkyl group having 1 to 6 carbon atoms. N1 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as X ¹ in the case of n1 is 2 or more.
In formula (3-2-1), R ³² represents a hydrogen atom or a methyl group, R ² and R ³ each independently represents an alkyl group having 1 to 3 carbon atoms, and X ² represents 1 to 6 carbon atoms. N2 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as X ² in the case of n2 is 2 or more.

In formula (3-4-1), R ³⁴ represents a hydrogen atom or a methyl group, R ⁵ represents an alkyl group having 1 to 3 carbon atoms, and X ⁴ represents a linear or branched alkyl group having 1 to 6 carbon atoms. Represents a group, n4 represents an integer of 0 to 4, and r represents an integer of 0 to 2. Incidentally, also includes having a plurality of different groups as X ⁴ in the case of n4 is 2 or more.
Wherein ^{(3-8-1), R 38} represents a hydrogen atom or a methyl group. R ³⁸¹ , R ³⁸² and R ³⁸³ each independently represent a linear or branched alkyl group having 1 to 4 carbon atoms.

In formula (3-12-1), R ¹⁴ represents a hydrogen atom or a methyl group, and G ₅ represents a single bond, —O—C (═O) —, —C (═O) —O—, or —O. -Represents.
L ¹⁰ represents a single bond, a linear or branched alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group or a derivative thereof, or a cyclic divalent hydrocarbon group. The hydrocarbon group may have a substituent and / or a hetero atom.
L ¹¹ represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group or a derivative thereof, or a cyclic divalent hydrocarbon group. The hydrocarbon group may have a substituent and / or a hetero atom.
h5 represents an integer of 0 to 2.

X ⁵ is an ester of a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alcohol having 1 to 6 carbon atoms. Represents a carboxy group or an amino group. The linear or branched alkyl group having 1 to 6 carbon atoms of X ⁵ is a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms as a substituent. It may have at least one group selected from the group consisting of a carboxy group, a cyano group and an amino group esterified with an alcohol.
h51 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as X ⁵ in the case of h51 is 2 or more.
g17, g19, and g21 each independently represents an integer of 0 or 1. g18 and g20 each independently represents an integer of 0 to 20.

R ⁶¹⁵ and R ⁶¹⁶ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms. Alternatively, R ⁶¹⁵ and R ⁶¹⁶ together represent —O—, —S—, —NH— or a methylene chain having a chain length of 1-6.
R ⁶¹⁷ and R ⁶¹⁸ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms. Alternatively, R ⁶¹⁷ and R ⁶¹⁸ together represent —O—, —S—, —NH—, or a methylene chain having a chain length of 1-6.
R ⁶¹⁹ represents a linear alkyl group having 1 to 3 carbon atoms.
^R620 represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, or a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof together with the carbon atoms to which R620 is bonded. Or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof may be formed.

The structural unit (B) derived from the monomer having an acid leaving group can be used alone or in combination of two or more as required.
Although the monomer (b) having an acid leaving group is not particularly limited, for example, the following formulas (9-1), (9-2), (9-5), (9-19), (9 -20), (9-22), (9-23), (9-114), (9-116), (9-197), (9-209), (9-241) A monomer is mentioned. In the formula, R and R ′ each independently represents a hydrogen atom or a methyl group.

  Among these, from the points of sensitivity and resolution, the above formulas (9-1), (9-2), (9-5), (9-19), (9-20), (9-22), (9- 23), (9-114), monomers represented by (9-116), and geometrical isomers and optical isomers thereof are more preferable.

From the viewpoint of good pattern rectangularity, monomers represented by the above formulas (9-197) and (9-209), and geometrical isomers and optical isomers thereof are more preferable.
Further, from the viewpoint of the storage stability of the resist composition, the monomer represented by the above formula (9-241), and geometrical isomers and optical isomers thereof are more preferable.

The structural unit other than the structural unit derived from the monomer having an acid leaving group is not particularly limited. Examples thereof include a structural unit (C) derived from a body.

First, a structural unit derived from a monomer having a lactone skeleton will be described. The structural unit (A) derived from a monomer having a lactone skeleton is preferable from the viewpoint of good substrate adhesion.
The content of the structural unit (A) derived from the monomer having a lactone skeleton is not particularly limited, but is preferably 30 mol% or more in the total structural unit of the polymer (P) from the viewpoint of adhesion to the substrate. 35 mol% or more is more preferable. Further, the content of the structural unit (A) having a lactone skeleton is preferably 60 mol% or less, more preferably 55 mol% or less in the total structural units of the polymer (P) from the viewpoint of the sensitivity and resolution of the resist. 50 mol% or less is more preferable.
The structural unit (A) derived from the monomer having a lactone skeleton is not particularly limited, but is selected from the group consisting of the following formulas (4-1) to (4-3) from the viewpoint of sensitivity or dry etching resistance. It is preferable that there is at least one.

In formula (4-1), R ⁴¹ represents a hydrogen atom or a methyl group, and R ⁴⁰¹ and R ⁴⁰² each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, Or a carboxyl group esterified with an alcohol having 1 to 6 carbon atoms, or R ⁴⁰¹ and R ⁴⁰² together form —O—, —S—, —NH—, or a chain length of 1 to 6 methylene chains [— (CH ₂ ) _j — (j represents an integer of 1 to 6)].

i represents 0 or 1, X ⁵ represents a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, carbon A carboxy group esterified with an alcohol having a number of 1 to 6 or an amino group is represented. The linear or branched alkyl group having 1 to 6 carbon atoms is a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alcohol having 1 to 6 carbon atoms as a substituent. It may have at least one group selected from the group consisting of esterified carboxy group, cyano group, and amino group.
n5 represents an integer of 0 to 4, and m represents 1 or 2. Incidentally, also includes having a plurality of different groups as X ⁵ in the case of n5 is 2 or more.

Wherein ^{(4-2), R 42} represents a hydrogen atom or a methyl ^group, R ^{201, R 202} are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, hydroxy group, carboxy Group or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms.
A ¹ and A ² each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms. Alternatively, A ¹ and A ² are combined together to form —O—, —S—, —NH— or a methylene chain having a chain length of 1 to 6 [— (CH ₂ ) _k — (k is 1 to 6). Represents an integer)].

X ⁶ is an ester of a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alcohol having 1 to 6 carbon atoms. Represents a carboxy group, a cyano group or an amino group. The linear or branched alkyl group having 1 to 6 carbon atoms is a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, or a cyano group. And at least one group selected from the group consisting of amino groups.
n6 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as X ⁶ in the case of n6 is 2 or more.

In formula (4-3), R ⁴² represents a hydrogen atom or a methyl group, and R ²⁰³ and R ²⁰⁴ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, Group or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms.
A ³ and A ⁴ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, or a carboxy group esterified with an alcohol having 1 to 6 carbon atoms. Alternatively, A ³ and A ⁴ are combined together to form —O—, —S—, —NH—, or a methylene chain having a chain length of 1 to 6 [— (CH ₂ ) ₁ — (l is 1 to 6 Represents an integer)].

X ⁷ is an ester of a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alcohol having 1 to 6 carbon atoms. Represents a carboxy group, a cyano group, or an amino group. The linear or branched alkyl group having 1 to 6 carbon atoms is a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, or a cyano group. And at least one group selected from the group consisting of amino groups.
n7 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as X ⁷ in the case of n7 is 2 or more.

The structural unit (A) derived from the monomer having a lactone skeleton can be used alone or in combination of two or more as required.
The monomer (a) having a lactone skeleton is not particularly limited. For example, the following formulas (10-1) to (10-5), (10-7), (10-8), (10-12) , (10-13), (10-17), and monomers represented by (10-23). In the formula, R represents a hydrogen atom or a methyl group.

  Among these, from the viewpoint of sensitivity, the monomers represented by the above formulas (10-1) to (10-3) and the above formula (10-5), and geometric isomers and optical isomers thereof are more preferable. From the viewpoint of dry etching resistance, monomers represented by the above formulas (10-7) and (10-12), and geometric isomers and optical isomers thereof are more preferable. From the viewpoint of solubility, the monomers represented by the above formulas (10-8), (10-13), (10-17), (10-23), geometric isomers, and optical isomerism thereof The body is more preferred.

Next, the structural unit (C) derived from the monomer having a hydrophilic group will be described. The structural unit (C) derived from the monomer having a hydrophilic group is preferable from the viewpoint of excellent pattern shape.
Here, the “hydrophilic group” is at least one selected from the group consisting of —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a methoxy group, a carboxy group, and an amino group.
The structural unit (C) having a hydrophilic group is effective in reducing the defect of the resist composition and improving the pattern rectangularity.
The content of the structural unit (C) derived from the monomer having a hydrophilic group is preferably 60% by mole or less, and preferably 5 to 30% by mole in the total structural unit of the polymer (P) from the viewpoint of pattern rectangularity. Is more preferable, and 10 to 25 mol% is still more preferable.

  The structural unit (C) derived from the monomer having a hydrophilic group is not particularly limited. However, from the viewpoint of high dry etching resistance required for the resist, the following formulas (5-1) to (5-3) and What is at least 1 sort (s) chosen from the group which consists of (5-8) is preferable.

In formula (5-1), R ⁵¹ represents a hydrogen atom or a methyl group, R ⁵⁰¹ represents a hydrogen atom, X ⁵¹ represents a linear or branched alkyl group having 1 to 6 carbon atoms, —C (CF ₃ ) _2- OH, a hydroxy group, a cyano group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, or an amino group. Represent.
The linear or branched alkyl group having 1 to 6 carbon atoms includes —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a carboxy group, an acyl group having 1 to 6 carbon atoms, It may have at least one group selected from the group consisting of a carboxy group esterified with 6 alcohols and an amino group. n51 represents an integer of 1 to 4. Incidentally, also includes having a plurality of different groups as X ⁵¹ in the case of n51 is 2 or more.

In formula (5-2), R ⁵² represents a hydrogen atom or a methyl group, and X ⁵² represents a linear or branched alkyl group having 1 to 6 carbon atoms, —C (CF ₃ ) ₂ —OH, a hydroxy group, cyano. A group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms, or an amino group. The linear or branched alkyl group having 1 to 6 carbon atoms includes —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a carboxy group, an acyl group having 1 to 6 carbon atoms, It may have at least one group selected from the group consisting of a carboxy group esterified with 6 alcohols and an amino group. n52 represents an integer of 1 to 4. Incidentally, also includes having a plurality of different groups as X ⁵² in the case of n52 is 2 or more.

In formula (5-3), R ⁵³ represents a hydrogen atom or a methyl group, R ⁵⁰² represents a hydrogen atom, and R ^{531 to} R ⁵³⁴ each independently represent a hydrogen atom, a straight chain or branched chain having 1 to 6 carbon atoms. Represents an alkyl group, and W ¹ and W ² are each independently —O—, —S—, —NH—, or a methylene chain having a chain length of 1 to 6 [— (CH ₂ ) _u2 — (u2 is 1 to 6). Represents an integer)].
X ⁵³ is a linear or branched alkyl group having 1 to 6 carbon atoms, —C (CF ₃ ) ₂ —OH, hydroxy group, cyano group, carboxy group, acyl group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms. An alkoxy group, a carboxy group esterified with an alcohol having 1 to 6 carbon atoms or an amino group, and n53 represents an integer of 1 to 4. The linear or branched alkyl group having 1 to 6 carbon atoms includes —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a carboxy group, an acyl group having 1 to 6 carbon atoms, It may have at least one group selected from the group consisting of a carboxy group esterified with 6 alcohols and an amino group. q1 represents 0 or 1. Incidentally, also includes having a plurality of different groups as X ⁵³ in the case of n53 is 2 or more.

In formula (5-8), R ¹⁰ represents a hydrogen atom or a methyl group, and G ₁ represents a single bond, —C (═O) —O—, —O—, or —O—C (═O) —. Represent. L ¹ and L ² each independently represent a single bond, a linear alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group or a derivative thereof, or a cyclic divalent hydrocarbon group. The cyclic divalent hydrocarbon group may have a substituent and / or a hetero atom. L ³ represents a single bond or a linear alkyl group having 1 to 3 carbon atoms. h1 represents an integer of 1 to 4. X ¹ is an ester of a linear or branched alkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alcohol having 1 to 6 carbon atoms. Represents a carboxy group or an amino group.

The linear or branched alkyl group having 1 to 6 carbon atoms of X ¹ is a hydroxy group, a carboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms. It may have at least one group selected from the group consisting of a carboxy group, a cyano group and an amino group esterified with an alcohol. h11 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as X ¹ in the case of h11 is 2 or more. h1 + h11 ≦ 7. Y ¹ represents —C (═O) —OH or —OH. g1 is 0 to 2, and g2 and g3 each independently represent an integer of 0 or 1. However, when L ¹ has ¹ carbon, both g 1 and g 2 are 0.

The structural unit (C) derived from the monomer having a hydrophilic group can be used alone or in combination of two or more as required.
The monomer (c) having a hydrophilic group is not particularly limited, and examples thereof include the following formulas (13-1), (13-4), (13-26), (13-27), and (13-30). ), (13-31), (13-33), (13-79), (13-80), (13-81), and monomers represented by (13-83). In the formula, R represents a hydrogen atom or a methyl group.

  Among these, from the viewpoint of good solubility in a resist solvent, the above formulas (13-1), (13-4), (13-26), (13-27), (13-30), (13-31) ), (13-79), and geometric isomers thereof, and optical isomers thereof are more preferable.

  From the viewpoint of high dry etching resistance, the monomers represented by the above formulas (13-26), (13-27), and (13-30), and geometric isomers and optical isomers thereof are More preferred.

  Further, from the viewpoint of defects and line edge roughness, the monomers represented by the above formulas (13-80), (13-81), and (13-83), and their geometric isomers and optical isomers are more Among these, monomers represented by the above formulas (13-80) and (13-83), and geometric isomers and optical isomers thereof are more preferable from the viewpoint of resist sensitivity.

  Examples of the structural unit (E) derived from other monomer include a structural unit (E1) having an alicyclic skeleton (nonpolar alicyclic skeleton) that does not have an acid-eliminable group and a hydrophilic group. be able to. Here, the alicyclic skeleton is a skeleton having one or more cyclic saturated hydrocarbon groups. The structural unit (E1) can be used alone or in combination of two or more as necessary.

The structural unit (E1) is preferable because it tends to exert an effect of developing the dry etching resistance of the resist composition.
The structural unit (E1) is not particularly limited, but structural units represented by the following formulas (11-1) to (11-4) are preferable from the viewpoint of high dry etching resistance required for the resist.

In formula (11-1), R ³⁰¹ represents a hydrogen atom or a methyl group, X ³⁰¹ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and n301 represents an integer of 0 to 4. Note that in the case where n301 is 2 or more, X ³⁰¹ includes a plurality of different groups.
In formula (11-2), R ³⁰² represents a hydrogen atom or a methyl group, X ³⁰² represents a linear or branched alkyl group having 1 to 6 carbon atoms, and n302 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as ^{X 302} in the case of n302 is 2 or more.

In formula (11-3), R ³⁰³ represents a hydrogen atom or a methyl group, X ³⁰³ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and n303 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as ^{X 303} in the case of n303 is 2 or more. Moreover, p represents the integer of 0-2.
In formula (11-4), R ³⁰⁴ represents a hydrogen atom or a methyl group, X ³⁰⁴ represents a linear or branched alkyl group having 1 to 6 carbon atoms, and n304 represents an integer of 0 to 4. Incidentally, also includes having a plurality of different groups as ^{X 304} in the case of n304 is 2 or more. Moreover, p1 represents the integer of 0-2.
In the formulas (11-1) to (11-4), the position where X ³⁰¹ , X ³⁰² , X ³⁰³ and X ³⁰⁴ are bonded may be anywhere in the cyclic structure.

  The polymer containing the structural unit (E1) can be produced by polymerizing a monomer containing the monomer (e1) having a nonpolar alicyclic skeleton. The monomer (e1) is not particularly limited, and examples thereof include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate, and (meth) acrylic acid. Tricyclodecanyl, dicyclopentadienyl (meth) acrylate, and derivatives having a linear or branched alkyl group having 1 to 6 carbon atoms on the alicyclic skeleton of these compounds are preferred.

Examples of the other structural unit (E) include the structural unit (E2) other than the structural unit (E1) having a nonpolar alicyclic skeleton. As the structural unit (E2), one type may be used, or two or more types may be used in combination as required.
The polymer containing the structural unit (E2) can be produced by polymerizing a monomer including the monomer (e2).

The monomer (e2) is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-propyl (meth) acrylate, (meth ) Isopropyl acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, methoxymethyl (meth) acrylate, n-propoxyethyl (meth) acrylate, iso-propoxyethyl (meth) acrylate, (meth) N-butoxyethyl acrylate, iso-butoxyethyl (meth) acrylate, tert-butoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) 2-hydroxy-n-propyl acrylate, 4-hydroxy (meth) acrylate n-butyl, 2-ethoxyethyl (meth) acrylate, 1-ethoxyethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3, (meth) acrylic acid 3-tetrafluoro-n-propyl, (meth) acrylic acid 2,2,3,3,3-pentafluoro-n-propyl, methyl α- (tri) fluoromethylacrylate, α- (tri) fluoromethylacrylic Ethyl acetate, 2-ethylhexyl α- (tri) fluoromethyl acrylate, n-propyl α- (tri) fluoromethyl acrylate, iso-propyl α- (tri) fluoromethyl acrylate, α- (tri) fluoromethyl acrylic N-butyl acid, iso-butyl α- (tri) fluoromethyl acrylate, tert-butyl α- (tri) fluoromethyl acrylate, α- (tri Methoxymethyl fluoromethyl acrylate, ethoxyethyl α- (tri) fluoromethyl acrylate, n-propoxyethyl α- (tri) fluoromethyl acrylate, iso-propoxyethyl α- (tri) fluoromethyl acrylate, α- ( (Meth) having a linear or branched structure such as n-butoxyethyl tri) fluoromethyl acrylate, iso-butoxyethyl α- (tri) fluoromethyl acrylate, tert-butoxyethyl α- (tri) fluoromethyl acrylate Acrylic ester;
2-methyl-2,4-butanediol di (meth) acrylate, 2,5-dimethyl-2,5-hexanediol di (meth) acrylate, 1,4-butanediol di (1- (meth) acryloyloxy) Ethyl ether, 1,4-butanediol di (1- (meth) acryloyloxy) methyl ether, (meth) acryloyloxyethylene glycol dimer (1- (meth) acryloyloxy) ethyl ether, (meth) acryloyloxyethylene glycol dimer Polyfunctional (meth) acrylic acid ester having an acid-decomposable group such as (1- (meth) acryloyloxy) methyl ether;
Styrene, α-methylstyrene, vinyltoluene, p-hydroxystyrene, p-tert-butoxycarbonylhydroxystyrene, 3,5-di-tert-butyl-4-hydroxystyrene, 3,5-dimethyl-4-hydroxystyrene, aromatic alkenyl compounds such as p-tert-perfluorobutylstyrene and p- (2-hydroxy-iso-propyl) styrene;
Unsaturated carboxylic acids and carboxylic anhydrides such as (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride;
Examples thereof include ethylene, propylene, norbornene, tetrafluoroethylene, acrylamide, N-methylacrylamide, N, N-dimethylacrylamide, vinyl chloride, vinyl fluoride, vinylidene fluoride, and vinylpyrrolidone.

  The content of the structural unit (E1) and the structural unit (E2) is preferably in the range of 20 mol% or less from the viewpoint of resist sensitivity and resolution and pattern rectangularity.

Moreover, each structural unit of the polymer (P) of this invention can take arbitrary sequences. Accordingly, this polymer may be, for example, a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer.
Furthermore, the structure of the polymer (P) of the present invention can take any structure. Therefore, this polymer may have a linear structure, a branched structure called a dendrimer, a hyper-branched polymer or a star polymer, or a network structure.

Next, the manufacturing method of the polymer (P) of this invention is demonstrated.
Examples of the method for producing the polymer (P) satisfying the formula (1) include the following two methods.
(A) a method of producing by one polymerization,
(B) A method of mixing separately polymerized polymers.

First, the method (A) will be described. The method (A) is not particularly limited, and a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, or the like can be used.
Among these, the solution polymerization method is preferable from the viewpoint that the monomer remaining after the completion of the polymerization reaction needs to be removed and the molecular weight of the polymer needs to be relatively low in order not to reduce the light transmittance. Among the solution polymerization methods, the monomer component was heated to a predetermined polymerization temperature from the standpoint of easily obtaining a reproducible polymer with small variations in average molecular weight and molecular weight distribution due to differences in production lots. A polymerization method called a dropping polymerization method in which the polymerization vessel is dropped into a polymerization vessel is preferable.

The monomer component may be dropped only with the monomer component, or the monomer component may be dropped after being dissolved in an organic solvent (hereinafter also referred to as “dropping solvent”). Further, a part of the monomer component may be previously charged in the polymerization container, or a part of the monomer component may be dissolved in an organic solvent and then charged in the polymerization container in advance.
An organic 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 charging solvent is not previously charged in the polymerization vessel, the monomer component or the polymerization initiator is dropped into the polymerization vessel in the absence of the charging solvent.

The polymerization initiator may be dissolved in the monomer component or may be dissolved in the dropping solvent.
The monomer component and the polymerization initiator may be mixed in the same storage tank and then dropped into the polymerization container; they may be dropped into the polymerization container from independent storage tanks; They may be mixed immediately before being supplied to and dropped into the polymerization vessel.
One of the monomer component 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.

In this dropping polymerization method, a high molecular weight polymer is produced at the initial stage of the polymerization reaction, and then a low molecular weight polymer is produced as the polymerization reaction proceeds. Accordingly, the polymer (P) satisfying the formula (1) can be produced by supplying the structural unit (B) having an acid-eliminable group into the reaction system at the initial stage of the polymerization reaction.
Therefore, it is preferable that at least a part of the monomer (b) that gives the structural unit (B) having an acid-eliminable group is previously charged in the polymerization vessel.

As an example of a specific polymerization method, a mixture containing a monomer (G) having an acid leaving group and another monomer is added to a solution containing the monomer (F) having an acid leaving group. A method for producing a polymer to be supplied and polymerized, wherein the monomer (F) having an acid-eliminable group in a solution containing the monomer (F) having an acid-eliminable group is acid-eliminated. The manufacturing method which is 3-40 mol% of the monomer whole quantity (F + G) which has a sex group is mentioned. More specifically, in the production method, a solution containing the monomer (F) having 3 to 40 mol% of the acid leaving group in the total amount of the monomer (F + G) having an acid leaving group is polymerized. After being supplied to the vessel, a mixture containing the remaining monomer (G) having an acid leaving group and other monomers is supplied to the polymerization vessel.
If the monomer (F) having an acid leaving group is less than 3 mol%, the polymer composition becomes uniform and does not satisfy the formula (1). If it exceeds 40 mol%, the dissolution uniformity decreases, and the resist composition When used as an object, pattern defects called defects are likely to occur.
The monomer (F) having an acid leaving group in a solution containing the monomer (F) having an acid leaving group suppresses the occurrence of a pattern defect called a defect when used as a resist composition. From this point, 4 to 30 mol% is preferable, and 5 to 20 mol% is more preferable based on the total amount of the monomer having an acid leaving group (F + G).
In addition, the solution containing the monomer (F) having an acid leaving group may contain a solvent. The monomer (G) having an acid leaving group and a mixture containing other monomers can also contain a solvent. Further, the monomer (F) having an acid leaving group and the monomer (G) having an acid leaving group may be different types of monomers or the same type of monomers.

  Further, in this polymerization method, at least two types of monomer solutions having different monomer mole fractions are sequentially added according to the polymerization rate, monomer consumption rate and copolymerization reactivity ratio of each monomer. It is preferable to supply. When supplied in this manner, a resist composition in which the polymer (P) tends to satisfy the formula (1), the solubility in the developer is uniform, and the sensitivity, resolution, and depth of focus (DOF) are excellent. It tends to be obtained. Therefore, two or more types of feed solutions are prepared, and the mole fraction of monomer (b) in the first feed solution is the mole fraction of monomer (b) in the total amount of all feed solutions used in the polymerization reaction. It is preferable to make it larger.

Next, the method (b) will be described. With respect to the method (b), for example, the structural unit having a mass average molecular weight Mw and an acid-eliminable group rather than the designed value (Mw (P), P [α _A ]) of the target polymer (P). Polymer (V) having a large average molar fraction [α _A ] (that is, Mw (V)> Mw (P), V [α _A ]> P [α _A ]) and target polymer (P) Polymer (W) having a mass average molecular weight Mw and an average molar fraction [α _A ] of the structural unit having an acid-eliminable group smaller than the designed value (Mw (P), P [α _A ]) (that is, , Mw (W) <Mw (P), W [α _A ] <P [α _A ]), respectively, and mixing the resulting polymer (V) and polymer (W) is there.
Here, the mixing of the polymer (V) and the polymer (W) may be performed in the state of a reaction solution after the polymerization reaction, or in a powder state after undergoing a purification step called reprecipitation described later. You may mix, and you may mix in the state of the solution which melt | dissolved the refined polymer in the organic solvent.

  The mass average molecular weight Mw (P) of the polymer (P) of the present invention is not particularly limited, but when used as a resist polymer, it is 2,000 or more from the viewpoint of dry etching resistance and resist pattern shape. It is preferably 3,000 or more, more preferably 4,000 or more, and particularly preferably 5,000 or more. Further, when used as a resist polymer, the mass average molecular weight Mw (P) of the polymer (P) of the present invention is preferably 100,000 or less from the viewpoint of solubility in a resist solution and resolution. 50,000 or less, more preferably 30,000 or less, and particularly preferably 20,000 or less.

The molecular weight distribution (Mw / Mn) of the polymer (P) of the present invention is not particularly limited except that it is larger than 1, but when used as a resist polymer, it is 2 from the viewpoint of solubility in a resist solution and resolution. Is preferably 0.5 or less, more preferably 2.0 or less, and particularly preferably 1.8 or less.
Although the polymerization temperature in the dropping polymerization method is not particularly limited, it is usually preferably in the range of 50 to 150 ° C.

The organic solvent used in the dropping polymerization method is not particularly limited, and a known solvent can be used as a polymerization solvent. For example, a chain such as ether (diethyl ether, propylene glycol monomethyl ether (hereinafter also referred to as “PGME”) is used. Ether, tetrahydrofuran (hereinafter also referred to as “THF”), cyclic ethers such as 1,4-dioxane, and the like, esters (methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, propylene glycol monomethyl ether acetate (hereinafter “ PGMEA ”), γ-butyrolactone, etc., ketone (acetone, methyl ethyl ketone (hereinafter also referred to as“ MEK ”), methyl isobutyl ketone (hereinafter also referred to as“ MIBK ”), amide (N, N-dimethyl). Acetamide, N, N-dimethyl Formamide), sulfoxide (dimethylsulfoxide, etc.), hydrocarbons (aromatic hydrocarbons such as benzene, toluene, xylene, aliphatic hydrocarbons such as hexane, alicyclic hydrocarbons such as cyclohexane), mixed solvents thereof, etc. Is mentioned.
These solvents may be used alone or in combination of two or more.

The amount of the polymerization solvent used is not particularly limited and may be determined as appropriate. Usually, it is preferable to use within the range of 30-700 mass parts with respect to 100 mass parts of monomer whole quantity used for copolymerization.
In the dropping polymerization method, when two or more polymerization solvents are used, the mixing ratio of the polymerization solvent in the dropping solvent and the charged solvent can be set at an arbitrary ratio.
The monomer concentration of the monomer solution dropped into the organic solvent is not particularly limited, but is preferably in the range of 5 to 50% by mass.
In addition, the amount of the charged solvent is not particularly limited and may be determined as appropriate. Usually, it is preferable to use within the range of 30-700 mass parts with respect to 100 mass parts of monomer whole quantity used for copolymerization.

  Although it does not restrict | limit especially as a polymerization initiator, What generate | occur | produces a radical efficiently with a heat | fever is preferable. Examples of such polymerization initiators include 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis [2- (2-imidazoline- Azo compounds such as 2-yl) propane]; organic peroxides such as 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane and di (4-tert-butylcyclohexyl) peroxydicarbonate Etc.

In addition, when the polymer (P) of the present invention is used for an ArF excimer laser (wavelength: 193 nm) lithography application, the polymerization initiator is used because the light transmittance (transmittance with respect to light having a wavelength of 193 nm) is not reduced as much as possible. It is preferable to use those having no aromatic ring in the molecular structure. Furthermore, in consideration of safety during polymerization, the polymerization initiator preferably has a 10-hour half-life temperature of 60 ° C. or higher.
The amount of the polymerization initiator used is not particularly limited, but from the viewpoint of increasing the yield of the polymer (P), 0.3 mol part or more is preferable with respect to 100 mol parts of the total amount of monomers used for copolymerization. 1 mol part or more is more preferable. Moreover, from the point which narrows molecular weight distribution of a polymer (P), 30 mol part or less is preferable with respect to 100 mol part of monomer whole quantity used for copolymerization.

  Moreover, when using the polymer (P) of this invention for a lithography use, you may use a chain transfer agent (henceforth a chain transfer agent) in the range which does not inhibit the storage stability of a resist composition. Examples of such chain transfer agents include 1-butanethiol, 2-butanethiol, 1-octanethiol, 1-decanethiol, 1-tetradecanethiol, cyclohexanethiol, 2-methyl-1-propanethiol, 2- Examples include hydroxyethyl mercaptan. In this case, the chain transfer agent preferably does not have an aromatic ring from the viewpoint of reducing the light transmittance (transmittance with respect to light having a wavelength of 193 nm) as much as possible.

  The polymer solution produced by solution polymerization is adjusted to a suitable solution viscosity with a good solvent such as 1,4-dioxane, acetone, THF, MEK, MIBK, γ-butyrolactone, PGMEA, PGME, and ethyl lactate, if necessary. After dilution, the polymer (P) is precipitated by dropping into a large amount of poor solvent such as methanol, water, hexane, heptane or the like. This process is generally called reprecipitation and is very effective for removing unreacted monomers, polymerization initiators, and the like remaining in the polymerization solution. If these unreacted substances remain as they are, there is a possibility that the resist performance may be adversely affected. Therefore, when the polymer (P) of the present invention is used for lithography, it is preferable to remove it as much as possible. The reprecipitation process may be unnecessary depending on circumstances. Thereafter, the precipitate is filtered off and sufficiently dried to obtain a polymer.

  In the polymer of the present invention thus obtained, the copolymer composition ratio varies depending on the molecular weight of the polymer chain, and the composition distribution is controlled by the formula (1). When compensated by the difference in copolymer composition ratio and used in resist compositions, the solubility in the developer is uniform, high sensitivity, high resolution, and excellent depth of focus (DOF). It is suitable as a coalescence, and is suitable as a polymer for fine processing used in the production of semiconductor elements and liquid crystal elements.

The polarity distribution of the polymer can be measured by LC analysis of the polymer of the present invention under the critical adsorption conditions described later.
If the elution curve obtained by LC analysis of the polymer under critical adsorption conditions is wider than that of the random copolymer (Pr) described later, this means that the polarity distribution of the polymer is wide. If the width is narrower than that of the random copolymer (Pr), it means that the polarity distribution of the polymer is narrow.
A narrow polarity distribution indicates that the ratio of the number of each structural unit in the polymer is uniform, and a wide polarity distribution indicates that the ratio of the number of each structural unit in the polymer is non-uniform. It shows that there is.

Next, a method for obtaining critical adsorption conditions for LC analysis will be described.
Using a production method described later, at least three random copolymers (Pr) having different mass average molecular weights are prepared. From the viewpoint of improving the measurement accuracy of the polar distribution of the polymer, it is preferable that the polymer having the smallest mass average molecular weight is in the range of 1,000 to 5,000. For example, when preparing three random copolymers (Pr) having different mass average molecular weights, the mass average molecular weights are 1,000 to 5,000, 5,000 to 8,000, and 8,000, respectively. It is preferable to be in the range of ˜20,000.

  After separating these random copolymers (Pr) having different mass average molecular weights in a solvent (S) described later, a separation column filled with an appropriate separation gel (SG), separation column temperature, eluent type, detector LC analysis is performed to obtain elution curves of random copolymers (Pr) having different mass average molecular weights. Here, the separation column temperature is preferably 100 ° C. or lower because the eluent does not decompose or volatilize, and preferably 0 ° C. or higher because the viscosity of the eluent is low.

Then, the type of separation gel (SG), the separation column temperature, and the type of eluent are appropriately changed until the peak tops of the obtained elution curves all match.
For example, when the peak top of the elution curve appears from a large mass average molecular weight to a small one as the elution time becomes longer, since the size exclusion mode is set, the random copolymer (Pr) is poor. By adding a solvent to the eluent, lowering the separation column temperature, or changing the type of separation gel (SG) to one that easily interacts with the random copolymer (Pr), all the peak tops of the elution curve Can be matched.
On the other hand, if the peak top of the elution curve appears from a small mass average molecular weight to a large one as the elution time becomes longer, it is in the adsorption mode, so that the good solvent for the random copolymer (Pr) All the peak tops of the elution curve are matched by adding to the eluent, increasing the temperature of the separation column, or changing the type of separation gel (SG) to one that does not interact with the random copolymer (Pr). Can be made.

  In this way, the measurement conditions (separation gel (SG) type, separation column temperature, eluent type) in which the peak tops of the elution curves of the random copolymers (Pr) having different mass average molecular weights all coincide can be obtained. it can. This measurement condition becomes the critical adsorption condition for the random copolymer (Pr).

Next, the manufacturing method of the random copolymer (Pr) which consists of the same component as a polymer is demonstrated.
The method for producing the random copolymer (Pr) is preferably produced by the polymerization method referred to as dropping polymerization.

In addition, when copolymerizing using a monomer having a low polymerization rate, a part or all of the monomer having a low polymerization rate is previously charged in the polymerization vessel, and the remaining monomer is put into the polymerization vessel. It may be dropped, or the dropping rate of the monomer having a low polymerization rate may be faster than that of other monomers.
Furthermore, after determining the amount and type of the monomer charged into the polymerization vessel in advance according to the polymerization rate and copolymerization reactivity ratio, the remaining monomer may be dropped into the polymerization vessel.
And you may combine the preparation method of said monomer.

As described above, in order to determine the charging method of various monomers in order to obtain a random copolymer (Pr), the polymerization is first performed by dropping all of the monomers to be used into the polymerization vessel over a certain period of time. Simultaneously with the reaction, the reaction solution is sampled at regular intervals to obtain time change data of the consumption ratio of each monomer. In this method, if the time change of the consumption ratio of each monomer is constant, the random copolymer (Pr) is obtained by this method, and therefore it is not necessary to perform the following operation. Here, “the time change of the consumption ratio of each monomer is constant” means that the consumption ratio of each monomer obtained by sampling is within ± 5% of these average values. Suppose that
If the time change of the consumption ratio of each monomer is not constant in the above method, based on this data, select the above-mentioned method as appropriate, and sample the reaction solution at regular intervals again. Thus, the time change data of the consumption ratio of each monomer is obtained. This operation is repeated several times, and the monomer charging method is determined so that the change over time in the consumption ratio of each monomer obtained by sampling at regular intervals is constant.
In addition, the above-mentioned operation can be substituted by computer simulation using a polymerization rate constant, a collision frequency factor, a copolymerization reactivity ratio, and the like. In this case, it is preferable in that the working time can be greatly shortened.

  Furthermore, in order to narrow the molecular weight distribution of the obtained random copolymer (Pr), living anionic polymerization, living cationic polymerization, reversible addition-fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP), nitroxyl Controlled radical polymerization such as radical polymerization (NMP) and continuous polymerization of a flow tube type may be used in combination with the above-described production method, or may be used alone.

  The polymer solution produced by a method such as solution polymerization is subjected to the above-described reprecipitation step, if necessary, and then the precipitate is filtered and sufficiently dried to obtain a random copolymer (Pr). obtain. The reprecipitation process may be unnecessary depending on circumstances.

The mass average molecular weight of the random copolymer (Pr) is not particularly limited, but is preferably in the range of 1,000 to 30,000 from the viewpoint of improving the measurement accuracy of the polarity distribution of the resist polymer.
Further, the molecular weight distribution of the random copolymer (Pr) is not particularly limited, but is preferably 2.0 or less, and preferably 1.8 or less from the viewpoint that the measurement accuracy of the polarity distribution of the resist polymer is good. Is more preferably 1.6 or less, and particularly preferably 1.4 or less.

The method for measuring the polarity distribution of the polymer of the present invention is based on the critical adsorption chromatography method using a liquid chromatograph (LC) apparatus, and a commercially available LC apparatus can be used.
In the critical adsorption chromatography method, a mixture of a good solvent and a poor solvent (eluent) of a copolymer as a sample is used as a moving layer, inorganic and organic gels are used as a fixed layer, a sample, a gel, a sample, and an eluent In this method, the components are separated and detected by the polar distribution of one polymer chain of the copolymer as a sample, that is, the copolymer composition distribution, utilizing the interaction generated between the two. The eluent serving as the moving layer is pressure-fed at a constant flow rate by a constant-rate liquid feed pump. Inorganic and organic gels, which are fixed layers, are packed in a (analytical) column and used. A typical LC system consists of an eluent tank, a pump, a switching valve, a sampling loop, a switching valve, a guard column, an analytical column, a detector, and a waste liquid tank in the order in which the eluent flows. ing.

A polymer whose polarity distribution is to be measured is dissolved in a solvent in which the copolymer is completely dissolved to prepare a sample. The solvent (S) used is not particularly limited as long as it is a good solvent for the polymer or a mixed solvent in which the polymer is completely dissolved in a mixture of the good solvent and the poor solvent. For example, water, methanol, ethanol, isopropanol, etc. Alcohol solvents such as carbon tetrachloride, chloroform, methylene chloride, chlorobenzene and dichlorobenzene, nitrile solvents such as acetonitrile, hydrocarbon solvents such as hexane, heptane and cyclohexane, benzene, toluene and xylene. Aromatic solvents, acetate solvents such as ethyl acetate and butyl acetate, ketone solvents such as acetone and methyl ethyl ketone, ether solvents such as diethyl ether, diisopropyl ether, 1,4-dioxane and tetrahydrofuran, N, N-dimethyl Formamide (DM ), Can be used N, N-dimethylacetamide (DMAc) amide solvent such as, sulfo solvents such as dimethyl sulfoxide (DMSO), nitrogen-containing aromatic solvents such as pyridine, a weakly acidic solvent such as acetic acid. These solvents may be deuterated.
Among them, the solvent (S) is preferably an aromatic solvent / amide solvent, an aromatic solvent / sulfo solvent, a chlorine solvent / nitrile solvent from the viewpoint that the measurement accuracy of the polarity distribution of the polymer is good. A combination is preferred. Although it does not specifically limit as said combination, For example, benzene / DMF, toluene / DMAc, chloroform / acetonitrile, etc. are mentioned.

  Further, when preparing the sample, the polymer may be dissolved after being dried in a solid state, or the polymer solution after polymerization may be diluted with the above solvent to prepare a sample. The density | concentration of a sample is 0.05-10 mg / mL normally, Preferably it is 0.1-5 mg / mL. If the sample concentration is too low, the detection sensitivity will decrease and the molecular weight measurement accuracy will decrease, or the sample will be difficult to prepare.If the sample concentration is too high, it will exceed the measurement limit of the detector. Since the signal is too strong, there is a problem that the molecular weight measurement accuracy is lowered, which is not preferable. The amount of the sample injected into the LC device is usually 5 to 200 μL, preferably 10 to 100 μL. If the amount of sample is too small, there will be a problem that the detection sensitivity will decrease or the sample injection accuracy will decrease and the molecular weight measurement accuracy will decrease.If the amount of sample is too large, it will exceed the measurement limit of the detector. Since the signal is too strong, there is a problem that the molecular weight measurement accuracy is lowered, which is not preferable. The amount of the sample can be set to a desired amount by the LC apparatus.

  The eluent used as the moving layer needs to use two or more kinds of solvents having different solubility of the polymer in order to separate the copolymer composed of two or more kinds of structural units having different polarities according to the polarity. It becomes. Therefore, a good solvent for the polymer whose polar distribution is to be measured, or a solvent (S) in which the polymer is completely dissolved in a mixture of the good solvent and the poor solvent, as described above, is used. The same solvent (S) as that used for the preparation is used, but the mixing composition ratio in the case of the mixed solvent is not particularly limited. The eluent is usually sent by a metering pump at a flow rate of 0.1 to 2.0 mL / min, preferably 0.2 to 1.0 mL / min. If the flow rate is small, the analysis time becomes long, and if the flow rate is large, the analysis accuracy decreases, which is not preferable. The liquid feeding accuracy of the metering liquid pump is usually within ± 1.0% to ± 0.5%. In addition, since the eluent used is a mixture of two or more types of solvents, a quantitative liquid feeding pump capable of mixing two or more types of solvents at an arbitrary ratio or changing the mixing ratio with time. Two or more units are preferably provided. Moreover, in order to mix two or more types of solvents uniformly, it is preferable to provide a mixing column between the metering liquid pump and the switching valve. Furthermore, it is preferable to provide a deaeration device between the eluent tank and the metered liquid feed pump because minute bubbles present in the eluent are removed and the liquid feed speed is stabilized.

The eluent sent out by the fixed liquid feed pump is sent to the analytical column, but there is a sample injection mechanism in front of the analytical column. The sample injection mechanism has a configuration of switching valve + sampling loop + switching valve. The sampling loop is a part for temporarily storing the sample. In a state where the eluent constantly flows, the eluent is sent to the analytical column without passing through the sampling loop. At the time of sample injection, a switching valve provided on both sides of the sampling loop is switched to the sample side, so that the sample in the sampling loop is sent to the analytical column.
In the method for measuring the polarity distribution of the present invention, the capacity of the sampling loop is usually 10 to 200 μL, preferably 10 to 50 μL. The sampling loop capacity is set by replacing the sampling loop with a desired capacity. For example, 10, 20, 50, 100 and 200 μL sampling loops are commercially available from Tosoh Corporation. The volume of the sampling loop to be used is determined by a ratio to the amount of sample (here, sampling loop volume / sample amount = sampling loop volume ratio). The sampling loop capacity ratio is usually 1 to 10, preferably 1 to 5, and particularly preferably 1 to 3. When the amount of sample, the volume of the sampling loop, and the volume ratio of the sampling loop are in the above ranges, the volume balance is excellent and the measurement accuracy of the polymer polarity distribution is good.

  A guard column is disposed between the analysis column and the sample injection mechanism as necessary. The guard column is, for example, for removing unnecessary components and foreign matters in the eluent in the sample and preventing the analysis column from deteriorating.

  As the fixed layer, an inorganic or organic gel (hereinafter referred to as “separation gel (SG)”) is packed in a separation column and used. The total length of the separation column is 50 cm or less, preferably 10 cm or more, particularly preferably 10 cm or more and 40 cm or less. For example, when one 15 cm column is used, it is preferably 1 to 3 in series, particularly preferably one. The inner diameter of the column is not particularly limited, but is usually 7 mm or less, preferably 5 mm or less. The separation gel (SG) can be selected according to the polarity of the sample to be measured, such as silica gel, polyvinyl alcohol gel, polyhydroxyacrylate gel, polyacrylate gel, polystyrene-divinylbenzene gel, alumina, carbon, and the like. Moreover, you may use what gave the chemical modification with a C4-C18 alkyl chain, a phenyl group, a cyano group, an amino group, a sulfo group, diol, a glyceropropyl group, etc. with respect to said stationary phase. . Among these, unmodified silica gel and silica gel chemically modified with an alkyl chain having 4 to 18 carbon atoms are preferable from the viewpoint of good measurement accuracy of the polarity distribution of the resist polymer.

The separation gel (SG) is generally in the form of particles, and the particle size is usually 1 μm to 100 μm. Especially, the thing of the range of 2 micrometers-20 micrometers is preferable, and the thing of the range of 3 micrometers-10 micrometers is more preferable from the point from which the measurement precision of the polar distribution of a resist polymer becomes favorable. The particle size is a value in a tetrahydrofuran (hereinafter sometimes referred to as THF) solvent because the degree of swelling varies depending on the type of eluent.
The pore size of the separation gel (SG) is usually 1 nm to 200 nm. Especially, the thing of the range of 10 nm-150 nm is preferable from the point from which the measurement precision of the polar distribution of a polymer becomes favorable, and the thing of the range of 20 nm-100 nm is further more preferable.
Such a separation gel (SG) having a particle size is commercially available from a liquid chromatography apparatus company or the like. For example, a separation column having a particle size of 5 μm, a pore size of 30 nm, and packed with silica gel as a separation gel (SG) is commercially available from GL Science as Inertsil Wp-300 Sil.

Moreover, as a separation gel (SG), the thing which is a continuous structure from the point from which the measurement precision of the polar distribution of a polymer becomes favorable is preferable. This continuous structure has mesh-like macropores and mesopores in the continuous structure itself. The sizes of macropores and mesopores are usually in the range of 1 μm to 5 μm and 5 to 20 nm, respectively. Such a continuous structure separation gel (SG) is commercially available from a liquid chromatography equipment company or the like. For example, a separation column filled with a columnar silica continuous material having an average size of macropores and mesopores of 2 μm and 13 nm and modified with an alkyl group having 18 carbon atoms as a separation gel (SG) is available from Merck. It is marketed as RP-18e.
By using the separation gel (SG) as described above as the column filler with the full length of the analytical column as described above, the balance of the interaction between the separation gel (SG) and the resist polymer is improved, and the analysis is performed. The accuracy is good and the molecular weight can be measured in a short time.

  Since the sample flowing out from the separation column is separated by the polarity of one polymer chain of the copolymer, the proportion of the polar fraction component of the copolymer is detected by detecting this with an appropriate detector. it can. As detectors, UV / Vis absorbance (UV-Vis) detector, fluorescence detector, differential refractive index (RI) detector, multi-wavelength detector, conductivity detector, electrochemical detector, evaporative light scattering detection (ELSD), charged particle detector, viscometer, mass analyzer (MSD), nuclear magnetic resonance (NMR) apparatus, infrared (IR) spectrophotometer. Among them, ELSD and charged particle detector are preferable because they can be used even when the light transmittance in the ultraviolet light and visible light regions of the eluent is low. Further, NMR is preferable because the copolymer composition ratio governing the polarity of the copolymer can be directly determined. A data processor is connected to the detector, and usually the polarity of the polymer is quantified by a method described later using a computer or the like.

  The separation column and preferably the detector are placed in a thermostat and maintained at a constant temperature. This is to eliminate disturbance of measurement accuracy during polarity measurement as much as possible and improve analysis accuracy. The column is usually maintained at a temperature slightly higher than room temperature to room temperature, and the temperature control accuracy is preferably ± 0.2 ° C. or less, particularly preferably ± 0.1 ° C. or less.

In order to quantify the polarity of the polymer, it is necessary to capture the signal intensity of the detector corresponding to the elution time (= the polarity of the polymer) by a signal processing device such as the computer described above.
The polarity corresponding to each elution time can be roughly grasped by the type of separation gel (SG) packed in the separation column used, and several types of compounds with known polarities such as solubility parameters are prepared, A calibration curve can also be prepared from the results of LC analysis.
For example, when the separation gel (SG) to be used is a high-polarity gel such as silica gel, polyvinyl alcohol gel, polyhydroxyacrylate gel, silica gel chemically modified with cyano group, amino group, sulfo group, diol, glyceropropyl group, etc. Since it becomes a normal phase system, it elutes in order from a low polarity substance. Conversely, in the case of a low-polarity gel such as silica gel chemically modified with an alkyl chain having 4 to 18 carbon atoms, a reverse phase system is used, so that the substances with higher polarity are eluted in order.
On the other hand, since the signal intensity of the detector is the concentration of the substance detected at that time, the part with high signal intensity has a high substance concentration, and conversely, the part with low signal intensity has a low substance concentration.
Since the elution curve generally has a peak of the signal intensity of the detector, the elution time for the peak position can be quantified as the average polarity of the polymer, and the signal intensity of the detector starts to rise. The time range from the elution time to the elution time converged to the baseline can also be quantified as the polarity distribution of the polymer.

The polymer of the present invention can measure the polarity distribution of the polymer by comparing the solubility parameter δ, which can be determined by the method for measuring the solubility parameter of the polymer described later.
The solubility parameter δ indicates that the larger the value, the greater the hydrophilicity or polarity, while the smaller the value, the smaller the hydrophilicity or polarity.
Further, the solubility parameter δ obtained by the method described later is a value reflecting the hydrophilicity or polarity of the high molecular weight component because the influence of the high molecular weight component appears greatly.

The polymer solubility parameter is measured by adding 0.10 g of polymer and 10.00 mL (= Vt) of tetrahydrofuran to a 50 mL glass bottle to prepare a polymer solution. Pure water is added until the polymer solution becomes slightly cloudy. Similarly, using hexane and acetonitrile instead of pure water, these solvents are added until the polymer solution becomes slightly cloudy.
The above operation is repeated three times for each solvent combination, and the average usage volumes of pure water, hexane, and acetonitrile three times are defined as Vw (mL), Vh (mL), and Va (mL), respectively.
And the solubility parameter (delta) of a polymer is calculated | required using following formula (I)-(IV). In addition, δd, δp, and δh are solubility parameters reflecting the molar attractive force, dipole moment, and hydrogen bond in δ of the polymer, respectively. The values of δd, δp, and δh of each solvent were referred to Polymer Handbook 4th edition (J. Brandrup, EH Immergut, EA Grulke, Ed., John Wiley & Sons, NY, 1999).

Next, the resist composition of the present invention will be described.
The resist composition of the present invention is obtained by dissolving the polymer (P) of the present invention in a solvent. In addition, without separating the polymer from the polymer solution obtained by solution polymerization or the like, the polymer solution is used as it is for the resist composition, or the polymer solution is diluted with an appropriate solvent, or It can also be concentrated and used in a resist composition. In addition, after filtering the polymer obtained in the reprecipitation step, it is used in the resist composition as a wet powder without being dried, or the polymer wet powder is dissolved in an appropriate solvent and then concentrated. A polymer solution can also be used in the resist composition.

Examples of the solvent include linear or branched ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), 2-pentanone and 2-hexanone; cyclic ketones such as cyclopentanone and cyclohexanone; propylene glycol monomethyl ether Propylene glycol monoalkyl acetates such as acetate (PGMEA) and propylene glycol monoethyl ether acetate; Ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate; Propylene glycol monomethyl ether (PGME), Propylene glycol monoalkyl ethers such as propylene glycol monoethyl ether; ethylene glycol Ethylene glycol monoalkyl ethers such as dimethyl glycol ether and ethylene glycol monoethyl ether; diethylene glycol alkyl ethers such as diethylene glycol dimethyl ether and diethylene glycol monomethyl ether; esters such as ethyl acetate and ethyl lactate; n-propyl alcohol, isopropyl alcohol, n Alcohols such as butyl alcohol, cyclohexanol, 1-octanol; 1,4-dioxane, ethylene carbonate, γ-butyrolactone; pentane, 2-methylbutane, n-hexane, 2-methylpentane, 2,2-dibutylbutane, 2,3-dibutylbutane, n-heptane, n-octane, isooctane, 2,2,3-trimethylpentane, n-nonane, 2,2,5-trimethylhexane n- decane, and aliphatic hydrocarbon solvents having a carbon number of 5 to 11 of n- dodecane and the like. These solvents may be used alone or in combination of two or more.
Among these, PGMEA, ethyl lactate, cyclohexanone, and γ-butyrolactone are preferable because they are widely used in terms of safety.

  The solution concentration of the polymer (P) is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less from the viewpoint of the viscosity of the polymer solution. The concentration of the polymer solution is preferably 2% by mass or more, more preferably 5% by mass or more, and further preferably 8% by mass or more from the viewpoint of the productivity of the polymer (P).

When the polymer (P) of the present invention is used for a chemically amplified resist composition, it is necessary to use a photoacid generator.
The photoacid generator contained in the chemically amplified resist composition can be arbitrarily selected from those that can be used as the acid generator of the chemically amplified resist composition. A photo-acid generator may use 1 type or may use 2 or more types together.

  Examples of such a photoacid generator include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinonediazide compounds, diazomethane compounds, and the like. As the photoacid generator, among them, onium salt compounds such as sulfonium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts are preferable, specifically, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, Triphenylsulfonium naphthalenesulfonate, (hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate, diphenyliodonium hexafluoroantimonate, p-methylphenyldiphenylsulfonium nonafluorobutanesulfonate, Tri (tert-butylphenyl) sulfonium trifluor B methanesulfonate, and the like.

  The content of the photoacid generator is appropriately determined depending on the type of the photoacid generator selected, but is usually 0.1 parts by mass or more and 0.5 parts by mass with respect to 100 parts by mass of the resist polymer. More preferably. By setting the content of the photoacid generator within this range, a chemical reaction due to the catalytic action of the acid generated by exposure can be sufficiently caused. Moreover, content of a photo-acid generator is 20 mass parts or less normally with respect to 100 mass parts of resist polymers, and it is more preferable that it is 10 mass parts or less. By setting the content of the photoacid generator within this range, the stability of the resist composition is improved, and the occurrence of uneven coating during application of the composition and scum during development is sufficiently reduced.

  Furthermore, a nitrogen-containing compound can also be mix | blended with a chemically amplified resist composition. By containing a nitrogen-containing compound, the resist pattern shape, the stability over time, and the like are further improved. In other words, the cross-sectional shape of the resist pattern is closer to a rectangle, and the resist film is exposed, post-exposure baked (PEB), and left for several hours before the next development process. However, the deterioration of the cross-sectional shape of the resist pattern is further suppressed when such leaving (aging) is performed.

Any known compound can be used as the nitrogen-containing compound, but an amine is preferable, and among them, a secondary lower aliphatic amine and a tertiary lower aliphatic amine are more preferable.
Here, the “lower aliphatic amine” refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms.
Examples of the secondary lower aliphatic amine and tertiary lower aliphatic amine include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, and triethanolamine. Is mentioned. Among these nitrogen-containing compounds, tertiary alkanolamines such as triethanolamine are more preferable.

The nitrogen-containing compound may be used alone or in combination of two or more.
The content of the nitrogen-containing compound is appropriately determined depending on the type of the selected nitrogen-containing compound, but is usually preferably 0.01 parts by mass or more with respect to 100 parts by mass of the resist polymer. By setting the content of the nitrogen-containing compound within this range, the resist pattern shape can be made more rectangular. Moreover, it is preferable that content of a nitrogen-containing compound is 2 mass parts or less normally with respect to 100 mass parts of resist polymers. By setting the content of the nitrogen-containing compound within this range, it is possible to reduce the sensitivity deterioration.

The chemically amplified resist composition may also contain an organic carboxylic acid, a phosphorus oxo acid, or a derivative thereof. By containing these compounds, it is possible to prevent sensitivity deterioration due to the compounding of the nitrogen-containing compound, and further improve the resist pattern shape, the stability with time of standing, and the like.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are preferable.

Phosphorus oxoacids or derivatives thereof include, for example, phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid and derivatives thereof; phosphonic acid, phosphonic acid dimethyl ester Phosphonic acids such as phosphonic acid di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester, etc. and derivatives thereof; phosphinic acids such as phosphinic acid, phenylphosphinic acid and their Examples thereof include derivatives such as esters, and among them, phosphonic acid is preferable.
These compounds (organic carboxylic acid, phosphorus oxo acid, or derivatives thereof) may be used alone or in combination of two or more.

The content of these compounds (organic carboxylic acid, phosphorus oxo acid, or derivative thereof) is appropriately determined depending on the type of the selected compound and the like. It is preferably 01 parts by mass or more. By setting the content of these compounds within this range, the resist pattern shape can be made more rectangular. Further, the content of these compounds (organic carboxylic acid, phosphorus oxo acid, or a derivative thereof) is usually preferably 5 parts by mass or less with respect to 100 parts by mass of the resist polymer. By reducing the content of these compounds within this range, the film loss of the resist pattern can be reduced.
Note that both the nitrogen-containing compound and the organic carboxylic acid, phosphorus oxoacid, or a derivative thereof can be contained in the chemically amplified resist composition of the present invention, or only one of them can be contained. .

Furthermore, 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. it can. Any of these additives can be used as long as it is known in the art. Moreover, the compounding quantity of these additives is not specifically limited, What is necessary is just to determine suitably.
The polymer (P) of the present invention can also be suitably used as a resist composition for metal etching, photofabrication, plate making, hologram, color filter, retardation film and the like.

  An example of evaluating the uniform solubility of the resist composition of the present invention in a developing solution will be described. Resist Development Analyzer MODEL-RDA790 (trade name) manufactured by Risotech Japan Co., Ltd. and photoresist dissolution rate / measurement analysis software LEAP SET (trade name) are used. Specifically, the resist composition was evaluated according to the photoresist dissolution rate / measurement analysis software LEAP SET operation manual, and the "Dissolution Rate v / s Thickness" graph was drawn to calculate the dissolution rate in the developer. The uniform solubility of the resist composition in the developer can be evaluated based on whether or not the acceleration of the dissolution rate is always constant.

Next, an example of the manufacturing method of the board | substrate with which the pattern of this invention was formed is demonstrated.
First, the resist composition of the present invention is applied to the surface of a substrate to be processed such as a silicon wafer on which a pattern is formed by spin coating or the like. And the to-be-processed board | substrate with which this resist composition was apply | coated is dried by baking processing (prebaking) etc., and a resist film is manufactured on a board | substrate.
Next, the resist film thus obtained is irradiated with light having a wavelength of 250 nm or less through a photomask (exposure). The light used for exposure is preferably a KrF excimer laser, an ArF excimer laser or an F ₂ excimer laser, and particularly preferably an ArF excimer laser. It is also preferable to expose with an electron beam.

On the other hand, immersion exposure in which exposure is performed 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. May be performed.
After the exposure, heat treatment is appropriately performed (post-exposure baking, PEB), the substrate is immersed in an alkaline developer, and the exposed portion is dissolved and removed in the developer (development). Any known alkaline developer may be used. Then, after development, the substrate is appropriately rinsed with pure water or the like. In this way, a resist pattern is manufactured on the substrate to be processed.
Then, the processed substrate on which the resist pattern has been manufactured 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.
Moreover, the copolymerizability of the polymer, the polymer and the resist composition were evaluated as follows.

1. Measurement of mass average molecular weight Mw of polymer The mass average molecular weight (Mw (P)) of the polymer (P) was determined in terms of polystyrene by gel permeation chromatography under the following conditions (GPC condition I).
<GPC condition I>
Apparatus: Tosoh Corporation make, Tosoh high-speed GPC apparatus HLC-8220GPC (trade name).
Separation column: manufactured by Showa Denko, three Shodex GPC K-805L (trade name) connected in series.

Measurement temperature: 40 ° C.
Eluent: THF.
Sample: A solution obtained by dissolving 20 mg of the polymer (P) in 5 ml of THF and filtering through a 0.5 μm membrane filter.
Flow rate: 1 ml / min.
Injection volume: 0.1 ml.
Detector: differential refractometer.

Calibration curve I: 20 mg of standard polystyrene was dissolved in 5 ml of THF, and the solution was filtered through a 0.5 μm membrane filter. As the standard polystyrene, the following standard polystyrenes manufactured by Tosoh (both are 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).

2. Polymer preparative Polymer (P _H ) having a molecular weight greater than the weight average molecular weight (Mw (P)) of the polymer (P) and molecular weight equal to or less than the mass average molecular weight (Mw (P)) of the polymer (P) The polymer (P _L ) was _{separated from} the polymer (P) by the following method (procedures (1) to (4)).
(1) The mass average molecular weight (Mw (P)) of the polymer (P) was determined according to the GPC condition I.
(2) The GPC condition was changed to the following GPC condition II, and a standard curve II (relation between elution time and molecular weight) was determined using standard polystyrene.
(3) In the calibration curve II, the elution time T at which the molecular weight is Mw (P) determined in (1) above was determined.
(4) In the following GPC conditions II, the solution was injected in the polymer preparative column (P), aliquoted above components have been eluted before the elution time T obtained in (3) as P _H, the the has been eluted later elution time T components were fractionated as P _L.

<GPC condition II>
Apparatus: Tosoh Corporation make, Tosoh high-speed GPC apparatus HLC-8220GPC (trade name).
Preparative column: Showa Denko, Shodex GPC K-2005 (trade name) connected in series.
Measurement temperature: 40 ° C.
Eluent: THF.
Sample: A solution obtained by dissolving 120 mg of the polymer (P) in 5 ml of THF and filtering through a 0.5 μm membrane filter.
Flow rate: 4 ml / min.
Injection volume: 1 ml.
Detector: differential refractometer.

Calibration curve II: 120 mg of standard polystyrene dissolved in 5 ml of THF and injected into a preparative column under the above conditions using a solution filtered through a 0.5 μm membrane filter, and the relationship between elution time and molecular weight was determined. As the standard polystyrene, the following standard polystyrenes manufactured by Tosoh (both are 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).

3. Mole fraction of analysis each of the structural units of the composition of the polymer (the content of each structural unit) is determined by ^{1 H-NMR} measurement in the case where it can be determined by ^{the 1 H-NMR} measurement, by such overlapping proton peak ^When it could not be determined by ¹ H-NMR measurement, it was determined by ¹³ C-NMR measurement.
The measurement of ¹ H-NMR was carried out using JSX Corporation GSX-400 type FT-NMR (trade name) and a polymer solution of about 5% by mass (deuterated chloroform solution or deuterated dimethyl). The sulfoxide solution was put in a test tube having a diameter of 5 mmφ, and the measurement was performed 64 times in an observation frequency of 400 MHz and a single pulse mode. The measurement temperature was 40 ° C. when deuterated chloroform was used as the solvent, and 60 ° C. when deuterated dimethyl sulfoxide was used as the solvent.
^In the case of ¹³ C-NMR measurement, using a UNITY-INOVA type FT-NMR (trade name) manufactured by Varian Technologies, an approximately 20% by mass polymer deuterated dimethyl sulfoxide solution is a test tube having a diameter of 5 mmφ. Then, integration was performed 50000 times by the proton complete decoupling method in which the measurement temperature was 60 ° C., the observation frequency was 125 MHz, and the nuclear overhauser effect (NOE) was removed.

4). Analysis of Polarity Distribution of Polymer One eluent tank filled with chloroform / acetonitrile = 37% by volume / 63% by volume ultrasonically degassed in advance, one metered liquid feed pump PU-980 manufactured by JASCO Corporation, GL Sciences column jacket LCJ-250 equipped with 100 μL sample loop and switching valve, column jacket temperature controller NESLAB RTE-111, GL Sciences Inertsil Wp-300 C18 (stationary phase: 18 carbon atoms) 10 μm diameter silica gel chemically modified with an alkyl chain, column: 250 μm long × 4.6 mm inner diameter) connected separation column part, composed of an evaporative light scattering detector (ELSD) ELS-2100 manufactured by Polymer Laboratories Liquid chromatography (LC) equipment A sample solution in which 100 μg of the polymer was dissolved in 50 μL of the eluent was introduced, and LC measurement was performed. The eluent flow rate was 0.5 mL / min, the column oven temperature was 32 ° C., the ELSD gas flow rate and the detection temperature were 7.2 L / min and 65 ° C., respectively.

5). Measurement of Polymer Solubility Parameter 0.10 g of polymer and 10.00 mL (= Vt) of tetrahydrofuran are added to a 50 mL glass bottle to prepare a polymer solution. Pure water is added until the polymer solution becomes slightly cloudy. Similarly, using hexane and acetonitrile instead of pure water, these solvents were added until the polymer solution became slightly cloudy.
The above operation is repeated three times for each solvent combination, and the average usage volumes of pure water, hexane, and acetonitrile three times are defined as Vw (mL), Vh (mL), and Va (mL), respectively.
And the solubility parameter (delta) of the polymer was calculated | required using Formula (I)-(IV). In addition, δd, δp, and δh are solubility parameters reflecting the molar attractive force, dipole moment, and hydrogen bond in δ of the polymer, respectively. The values of δd, δp, and δh of each solvent were referred to Polymer Handbook 4th edition (J. Brandrup, EH Immergut, EA Grulke, Ed., John Wiley & Sons, NY, 1999).

<Synthesis Example 1>
In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, 7.8 parts of ethyl lactate was added in a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring.
Thereafter, the following mixture was dropped from the dropping funnel into the flask over 4 hours for polymerization, and further polymerized at that temperature for 3 hours.
α-methacryloyloxy-γ-butyrolactone (a monomer having no acid leaving group, hereinafter referred to as GBLMA) 3.1 parts,
4.2 parts of 2-methyl-2-adamantyl methacrylate (monomer having an acid leaving group, hereinafter referred to as MAdMA),
2.1 parts of 3-hydroxyadamantyl methacrylate (a monomer having no acid leaving group, hereinafter referred to as HAdMA),
14.1 parts ethyl lactate,
1.55 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).

Subsequently, the obtained reaction solution was added dropwise with stirring to about 10 times the amount of methanol / water = 80/20 (volume ratio) to obtain a white precipitate (polymer S1). The obtained precipitate was separated by filtration, and again poured into methanol / water = 90/10 (volume ratio) of about 10 times the amount of the reaction solution, and the precipitate was washed with stirring.
The washed precipitate was filtered off and dried at 40 ° C. under reduced pressure for about 40 hours. The obtained polymer S1 had a mass average molecular weight of 3,800 and an average copolymer composition ratio of GBLMA / MAdMA / HAdMA = 40.1 / 41.2 / 18.7 (mol%).

<Synthesis Example 2>
Synthesis Example 1 except that the amount of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)) was changed to 1.04 parts in the dropping solution In the same manner as above, a polymer S2 was obtained. The obtained polymer S1 had a mass average molecular weight of 7,400 and an average copolymer composition ratio of GBLMA / MAdMA / HAdMA = 40.4 / 41.1 / 18.5 (mol%).

<Synthesis Example 3>
Synthesis Example 1 except that the amount of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)) was changed to 0.52 parts in the dropping solution. In the same manner as above, a polymer S3 was obtained. The obtained polymer S3 had a mass average molecular weight of 17,900 and an average copolymer composition ratio of GBLMA / MAdMA / HAdMA = 39.9 / 41.3 / 18.8 (mol%).

<Measurement Example 1>
The polar distributions of the polymers S1 to S3 produced in Synthesis Examples 1 to 3 were analyzed. The obtained chromatogram is shown in FIG. Under the measurement conditions described above, the peak tops of the elution curves of the polymers S1 to S3 having substantially the same copolymer composition ratio and different mass average molecular weights coincided. That is, under the measurement conditions described above, the polymer having an average copolymer composition ratio of about GBLMA / MAdMA / HAdMA = 40/40/20 (mol%) is not affected by the molecular weight and is not affected by the molecular weight. It can be seen that they are separated by the composition distribution.

<Example 1>
A flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer was charged with 393.0 parts of MAdMA and 7900 parts of ethyl lactate under a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring. It was.
Thereafter, the following mixture (hereinafter also referred to as a dropping solution) was dropped from the dropping funnel into the flask over 4 hours for polymerization, and further polymerized at that temperature for 3 hours.
GBLMA2856 parts,
MAdMA3538 parts,
HAdMA 1982,
12560 parts ethyl lactate,
1020 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V-601 (trade name)).

The following operations were performed in the same manner as in Synthesis Example 1 to obtain a washed precipitate of the polymer P1.
The precipitate was filtered off, and 10 parts of the precipitate was dried at 40 ° C. under reduced pressure for about 40 hours. Table 2 shows each physical property and solubility parameter of the obtained polymer P1.
Moreover, the chromatogram obtained by the polar distribution analysis of the polymer P1 is shown in FIG.
From this polymer P1, the polymer P1 _H was fractionated, and the molar fraction of the structural unit (MAdMA unit) having an acid leaving group was measured. The obtained results are shown in Table 1.

On the other hand, the remaining precipitate separated by filtration was added to 88,000 parts of PGMEA, and after the polymer wet powder was completely dissolved, a nylon filter having a pore size of 0.04 μm (trade name: P-NYLON N66FILTER 0.04M, manufactured by Nippon Pole) And the copolymer solution was filtered.
Subsequently, methanol and water used for precipitation were distilled off by heating under reduced pressure, and PGMEA used for redissolving was further distilled off to obtain a polymer P1 solution having a polymer solution concentration of 25% by mass. It was. The maximum ultimate vacuum was 0.7 kPa, the maximum solution temperature was 65 ° C., and the distillation time was 8 hours.

<Example 2>
The same as Synthesis Example 1 except that the amount of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)) in the dropping solution was changed to 250 parts In this manner, a polymer P2 was obtained.
Table 2 shows physical properties and solubility parameters of the obtained polymer P2.
From this polymer P2, a sample was collected polymer P2 _H, it was measured molar fraction of the structural unit having an acid leaving group (MAdMA units). The obtained results are shown in Table 1.
Moreover, the polymer P2 solution was obtained by the same operation as Example 1 using the polymer P2 after precipitation washing.

<Comparative Example 1>
In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, a total amount of 7310 parts of ethyl lactate was placed in a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring.
Thereafter, the following mixture was dropped from the dropping funnel into the flask over 4 hours for polymerization, and further polymerized at that temperature for 3 hours.
GBLMA2856 parts,
MAdMA3931 parts,
HAdMA 1982,
13150 parts of ethyl lactate,
1062 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).

Subsequently, using the obtained reaction liquid, operation similar to Example 1 was performed and polymer P'1 was obtained. Table 2 shows the physical properties and solubility parameters of the polymer P′1.
Moreover, the chromatogram obtained by the polar distribution analysis of polymer P'1 is shown in FIG.
The polymer P′1 _H was fractionated from the polymer P′1, and the molar fraction of the structural unit having an acid leaving group (MAdMA unit) was measured. The obtained results are shown in Table 1.
Further, using this polymer P′1, the same operation as in Example 1 was performed to obtain a polymer P′1 solution.

<Comparative example 2>
Comparative Example 1 except that the amount of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)) was changed to 261 parts in the dropping solution. In this way, a polymer P′2 was obtained.
Table 2 shows physical properties and solubility parameters of the obtained polymer P′2.
This polymer P'2, a sample was collected polymer P'2 _H, it was measured molar fraction of the structural unit having an acid leaving group (MAdMA units). The obtained results are shown in Table 1.
Further, in the same manner as in Example 1, a polymer P′2 solution was obtained using the polymer P′2 after precipitation washing.

<Comparative Example 3>
In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, 7640 parts of ethyl lactate was put in a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring.
Thereafter, the following mixture was dropped from the dropping funnel into the flask over 4 hours for polymerization, and further polymerized at that temperature for 3 hours.
GBLMA 1785 parts,
MAdMA6388 parts,
HAdMA991 parts,
13750 parts of ethyl lactate,
380 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).

Subsequently, using the obtained reaction liquid, operation similar to the comparative example 1 was performed, and polymer P'3 was obtained. Table 2 shows the physical properties and solubility parameters of the polymer P′3.
This polymer P'3, a sample was collected polymer P'3 _H, it was measured molar fraction of the structural unit having an acid leaving group (MAdMA units). The obtained results are shown in Table 1.
Further, in the same manner as in Example 1, a polymer P′3 solution was obtained using the polymer P′3 after precipitation washing.

<Comparative example 4>
In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, 6750 parts of ethyl lactate was put in a nitrogen atmosphere, and the temperature of the hot water bath was raised to 80 ° C. while stirring.
Thereafter, the following mixture was dropped from the dropping funnel into the flask over 4 hours for polymerization, and further polymerized at that temperature for 3 hours.
GBLMA 4641 parts,
MAdMA 1474 parts,
HAdMA 1982,
12150 parts of ethyl lactate,
400 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)).

Subsequently, using the obtained reaction liquid, operation similar to the comparative example 1 was performed, and polymer P'4 was obtained. Table 2 shows the physical properties and solubility parameters of the polymer P′4.
The polymer P′4 _H was fractionated from the polymer P′4, and the molar fraction of the structural unit having an acid leaving group (MAdMA unit) was measured. The obtained results are shown in Table 1.
Moreover, polymer P'4 solution was obtained by operation similar to Example 1 using polymer P'4 after precipitation washing.

<Evaluation test>
From the results of the solubility parameter δ obtained in the above Examples and Comparative Examples, the polymer of Example 1 has a lower average polarity than the polymer of Comparative Example 1 having the same average molecular weight and ratio of the number of structural units. Was showing. This indicates that in the polymer of Example 1, the structural unit (MAdMA unit) having an acid-eliminable group, which is a low-polar structural unit among the structural units, is biased on the high molecular weight side. When the polymers of Example 2 and Comparative Example 2 are compared in the same manner, the polymer of Example 2 has a biased constituent unit (MAdMA unit) having an acid-eliminable group on the higher molecular weight side than the polymer of Comparative Example 2. Indicates that
2 and 3 obtained by the polarity distribution analysis, the polymer of Example 1 has a wider chromatogram distribution than the polymer of Comparative Example 1, and the polar distribution in the polymer is wider. Indicated. This indicates that the ratio of the number of each structural unit in the polymer of Example 1 is uneven and biased.

<Examples 3 and 4 and Comparative Examples 5 to 8>
About each polymer solution obtained by the said Example and comparative example, 400 parts of polymer solutions, 2 parts of triphenylsulfonium triflate which is a photo-acid generator, and a solvent so that a polymer concentration may be 12.5 mass%. PGMEA was mixed to make a uniform solution, and then filtered through a membrane filter having a pore size of 0.1 μm to prepare a resist composition solution. The obtained composition was spin-coated on a silicon wafer and prebaked at 120 ° C. for 60 seconds using a hot plate to produce a resist film having a thickness of 0.3 μm. Then, it was exposed with an ArF excimer laser having a wavelength of 193 nm through a mask, and then subjected to post-exposure baking at 120 ° C. for 60 seconds using a hot plate. Subsequently, it developed at room temperature using the 2.38 mass% tetramethylammonium hydroxide aqueous solution, wash | cleaned with the pure water, and dried and manufactured the resist pattern.
As a result, each of the polymers of Examples was excellent in sensitivity, resolution, and depth of focus (DOF), and a 0.16 μm line-and-space pattern was clearly and accurately obtained. However, when the polymer of the comparative example was used, the sensitivity, resolution, and depth of focus (DOF) were poor, and the pattern was not clear.

The polymer of the present invention contains 5 to 60 mol% of a structural unit derived from a monomer having an acid leaving group, and the composition distribution is controlled as shown in formula (1). The solubility in the developer is uniform, the sensitivity is high, the resolution is high, and the depth of focus (DOF) is excellent.
Therefore, the resist composition using the polymer of the present invention can be suitably used for DUV excimer laser lithography, these immersion lithography and electron beam lithography, particularly ArF excimer laser lithography, and this immersion lithography.

Claims (4)

A method for producing a resist polymer comprising 5 to 60 mol% of a structural unit derived from a monomer having an acid leaving group,
When the polymer was separated from the polymer (P _H ) having a molecular weight greater than the mass average molecular weight (Mw (P)) by gel permeation chromatography, the following formula (1) So that the polymer (P) satisfies
In a solution containing the acid-eliminable group-containing monomer (F) corresponding to 3 to 10 mol% of the total amount of the monomer having an acid-eliminable group (F + G), A method for producing a polymer, wherein a mixture containing a monomer (G) and other monomers is dropped and polymerized.
P [α _A ] / P _H [α _A ] ≦ 0.990 (1)
(In the formula (1), P [α _A ] is the ratio of the number of structural units derived from monomers having acid-leaving groups to the number of structural units derived from all monomers in the polymer (P). P _H [α _A ] represents the ratio of the number of structural units derived from the monomer having an acid-eliminable group to the number of structural units derived from all monomers of the polymer (P _H ). )   The method for producing a polymer according to claim 1, wherein the solution containing the monomer (F) having an acid leaving group does not contain a monomer other than the monomer (F). A step of producing a polymer by the production method according to claim 1 or 2,
A method for producing a resist composition, comprising a step of producing a resist composition using the obtained polymer. A step of producing a resist composition by the production method according to claim 3;
The manufacturing method of the board | substrate with which the pattern formed including the process of apply | coating the obtained resist composition on a to-be-processed substrate, the process of exposing with the light of a wavelength of 250 nm or less, and the process of developing using a developing solution is formed.