JP2019059957A - Production method of copolymer for lithography, production method of resist composition, and method for manufacturing patterned substrate - Google Patents

Abstract

To provide a production method of a copolymer for lithography, having a small proportion of a high molecular weight component, uniform solubility in a developer and capable of improving sensitivity when used for a resist composition, a production method of a resist composition, and a method for manufacturing a patterned substrate.SOLUTION: The production method of a copolymer for lithography comprises supplying a monomer (a) having an acid leaving group, a monomer (b) having no acid leaving group, and a polymerization initiator (c) into a reaction chamber to produce a polymer. In the copolymer produced and obtained by supplying 5 to 30 mass% of the polymerization initiator (c) in the whole supply amount to the reaction chamber in an initial 5% polymerization reaction period of the polymerization reaction period from the start of the polymerization to the end of the polymerization, a ratio N(v1)/Nave defined in the specification ranges from 1.01 to 1.20.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a copolymer for lithography, a method for producing a resist composition, and a method for producing a substrate having a pattern formed thereon.

In recent years, in the process of manufacturing semiconductor elements, liquid crystal elements, etc., miniaturization of pattern formation by lithography has been rapidly advanced. As a method of miniaturization, for example, shortening of the wavelength of irradiation light can be mentioned. As a copolymer for a chemically amplified resist used in ArF excimer laser lithography, a copolymer of (meth) acrylic ester which is transparent to light with a wavelength of 193 nm has attracted attention.
By the way, the copolymer of (meth) acrylic acid ester is generally polymerized by a radical polymerization method. Generally, when two or more monomers are copolymerized, the composition ratio of the monomer units of the copolymer formed at the initial stage of polymerization and the final stage of polymerization because the copolymerization reactivity ratio between the respective monomers is different. Is different. As a result, the composition ratio of the resulting copolymer may vary.

If the composition ratio of the monomer units of the copolymer varies, the solubility in the solvent tends to be low, and it takes a long time to dissolve in the solvent or is insoluble when preparing the resist composition. The occurrence of the component may cause problems in the preparation of the resist composition, such as an increase in the number of manufacturing steps. In addition, the sensitivity of the obtained resist composition tends to be insufficient.
As a method for solving the above-mentioned problems, for example, in Patent Document 1, in order to obtain a highly sensitive resist, a monomer solution and a polymerization initiator solution are supplied into a polymerization reaction system, and a single amount is initiated from the polymerization reaction start The standard deviation of the unreacted monomer composition ratio in the polymerization reaction system until the end of the supply of the body solution is 2
A method for producing a copolymer within the range has been proposed.

On the other hand, even a small amount of high molecular weight components generated in the polymerization process tends to have low solubility in solvents,
The sensitivity of the resulting resist composition tends to be insufficient.
As a method for solving the above problems, for example, in Patent Document 2, in order to suppress the formation of high molecular weight components, the monomer solution and the polymerization initiator solution are held in independent storage tanks, respectively, and Also, there has been proposed a method for producing a copolymer in which a polymerization initiator solution is first supplied into a polymerization reaction system.

Unexamined-Japanese-Patent No. 2010-202699 JP 2004-269855 A

However, even in the methods proposed in Patent Document 1 and Patent Document 2, the solubility of the copolymer in the solvent may be insufficient, and the lithography performance may not be improved.
The present invention has been made in view of the above-mentioned circumstances, and the production of a copolymer for lithography having a small proportion of high molecular weight components, uniform solubility in a developer, and capable of improving sensitivity when used in a resist composition It is an object of the present invention to provide a method, a method of manufacturing a resist composition, and a method of manufacturing a substrate on which a pattern is formed.

In the present invention, a monomer (a) containing an acid-eliminating group, a monomer (b) not containing an acid-eliminating group and a polymerization initiator (c) are supplied into a reactor to obtain a polymer. The molecular weight distribution (Mw / Mn) produced is
It is a manufacturing method of the copolymer for lithography which is 1.1-1.7 ,
The monomer (a) containing an acid leaving group has an ethylenic double bond, and contains the acid leaving group.
(B) contains a polar group, and the polymerization initiator (c) has a half-life temperature of 50 hours.
A thermal polymerization initiator which is at a temperature of
The initial 5% of the polymerization reaction period of the polymerization reaction period from Polymerization initiation to completion of polymerization, the polymerization initiator (
The copolymer obtained by feeding 5 to 30% by mass of the total feed of c) into the reactor is obtained
The present invention relates to a method for producing a copolymer for lithography, which satisfies the following conditions. (conditions)
In the elution curve obtained by gel permeation chromatography (GPC), the elution solution showing a peak related to the copolymer for lithography is most among the five fractions divided in the order of elution so as to equalize the volume. The ratio of the monomer unit (A) containing an acid leaving group among all the monomer units constituting the copolymer contained in the first fraction eluted earlier is N (v1) mol% N represents the ratio of the monomer unit (A) containing an acid leaving group among all the monomer units constituting the copolymer contained in the total of the five fractions, Nave mol%, N (V1) / Nave is 1.01 to 1.20.

In addition, the present invention is a method for producing a resist composition, which comprises the step of mixing the copolymer obtained by the method for producing a copolymer for lithography and a compound capable of generating an acid upon irradiation with an active energy ray or radiation. On the way.

Furthermore, in the present invention, a step of applying the resist composition obtained by the above method for producing a resist composition on a substrate to be processed, a step of exposing with light of a wavelength of 250 nm or less, and development using a developer And a process for producing a patterned substrate.

According to the method for producing a copolymer for lithography of the present invention, the proportion of a high molecular weight component is small, the solubility in a developer is uniform, and a copolymer for lithography capable of improving the sensitivity when used in a resist composition , A method of manufacturing a resist composition, and a method of manufacturing a substrate on which a pattern is formed.

It is explanatory drawing of the elution curve obtained by gel permeation chromatography (GPC).

In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acryloyloxy” means acryloyloxy or methacryloyloxy.
In the present specification, weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of copolymer
Is a value determined in terms of polystyrene by gel permeation chromatography (GPC).

<A monomer containing an acid leaving group (a)>
The process for producing a copolymer for lithography of the present invention comprises a monomer (a) containing an acid-eliminating group,
It copolymerizes with the monomer (b) which does not contain an acid leaving group.

The monomer (a) containing an acid leaving group may be a compound having an acid leaving group and a polymerizable functional group, and examples thereof include known monomers.

The acid eliminable group is a group having a bond which is cleaved by acid, and is a group from which part or all of the acid eliminable group is released from the main chain of the copolymer by cleavage of the bond. A copolymer containing a monomer unit (A) containing an acid-eliminating group reacts with an acid component in the resist composition to become soluble in an alkaline solution (developing solution), enabling formation of a resist pattern Play an action.

The polymerizable functional group is a group that forms a copolymer chain by polymerization reaction, and is preferably an ethylenic double bond because of excellent polymerization efficiency.

As a monomer (a) containing an acid leaving group, the (meth) acrylic acid ester etc. which have a C6-C20 alicyclic hydrocarbon group and an acid leaving group are mentioned, for example. As the monomers (a) containing these acid leaving groups, one type may be used alone, or two or more types may be used in combination.

The (meth) acrylic acid ester having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and an acid leaving group includes, for example, an alicyclic hydrocarbon group having 6 to 20 carbon atoms, (meth) (Meth) acrylic acid ester having a tertiary carbon atom at a binding site to an oxygen atom constituting an ester bond of acrylic acid ester; alicyclic hydrocarbon group having a carbon number of 6 to 20, alicyclic carbonized -COOR group (R represents a tertiary hydrocarbon group which may have a substituent, a tetrahydrofuranyl group, a tetrahydropyranyl group or an oxepanyl group.) Bonded to a hydrogen group directly or via a linking group (Meth) acrylic acid ester etc. are mentioned.

The alicyclic hydrocarbon group of the (meth) acrylic acid ester having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and an acid leaving group is an oxygen atom constituting an ester bond of the (meth) acrylic acid ester It may be directly bonded or may be bonded via a linking group such as an alkylene group.

Among the monomers (a) containing such an acid-eliminating group, the following monomers (a1), the following monomers (a2), and the following monomers (a3) are excellent because the sensitivity and resolution of the resist are excellent. ), Following monomers (
a4) is preferable, and since it enables formation of a resist pattern to be exposed to light having a wavelength of 250 nm or less, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, isopropyl adamantyl Meta) acrylate, 1
-(1'-adamantyl) -1-methylethyl (meth) acrylate, 1-methylcyclohexyl (meth) acrylate, 1-ethylcyclohexyl (meth) acrylate, 1-
Methylcyclopentyl (meth) acrylate, 1-ethylcyclopentyl (meth) acrylate, 1-ethylcyclooctyl (meth) acrylate is more preferable, 2-methyl-
More preferable are 2-adamantyl methacrylate, isopropyl adamantyl methacrylate, 1-ethylcyclohexyl methacrylate and 1-ethylcyclopentyl methacrylate.

What each alphabet in a monomer (a1), a monomer (a2), a monomer (a3), and a monomer (a4) represents is shown below.
R ³¹ , R ³² , R ³³ and R ³⁴ each independently represent a hydrogen atom or a methyl group.
R ¹ , R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 5 carbon atoms. The alkyl group may be linear or branched.
R ² and R ³ each independently represent an alkyl group having 1 to 3 carbon atoms. The alkyl group may be linear or branched.
Each of R ³³¹ , R ³³² , R ³³³ and R ³³⁴ independently represents a hydrogen atom or C 1 -C 1
6 represents an alkyl group. The alkyl group may be linear or branched.
Each of X ¹ , X ² , X ³ and X ⁴ independently represents an alkyl group having 1 to 6 carbon atoms. The alkyl group may be linear or branched.
n1, n2, n3 and n4 each independently represent 0-4. n1, n2, n3 or n4
When is two or more, a plurality of X ¹ , X ² , X ³ or X ⁴ exist in one monomer. Plural X ¹ , X ² , X ³ or X ⁴ may be the same or different.
Z ¹ and Z ² each independently represent -O-, -S-, -NH- or-(CH ₂ ) _k- . k represents an integer of 1 to 6;
q represents 0 or 1;
r represents an integer of 0 to 3;

<Monomer (b) containing no acid leaving group>
The process for producing a copolymer for lithography according to the present invention comprises a monomer (b) containing no acid leaving group
Is copolymerized with the monomer (a) containing an acid-eliminating group.

The monomer (b) not containing an acid leaving group may be appropriately selected according to the application and required performance,
Known monomers in the field of copolymers for lithography can be mentioned.

As a monomer (b) which does not contain an acid leaving group, the monomer containing a polar group etc. are mentioned, for example. These monomers (b) not containing an acid leaving group may be used alone or in combination of two or more.
Among the monomers (b) which do not contain these acid-eliminating groups, monomers having a polar group are preferable because they are excellent in the sensitivity and resolution of the resist.

<Monomer containing polar group (b ′)>
The monomer (b ′) containing a polar group may be a compound having a polar group and a polymerizable functional group, and includes known monomers.

The polar group is a functional group having polarity or a group having an atomic group having polarity, and includes, for example, a hydrophilic group such as a hydroxyl group, a cyano group, an alkoxy group, a carboxyl group, an amino group or a carbonyl group; A group containing a sulfur atom; a group containing a lactone skeleton; a group containing an acetal structure; a group containing an ether bond, and the like.

As the monomer (b ′) containing a polar group, for example, a monomer containing a lactone skeleton, a monomer containing an acetal structure, a monomer containing an ether bond, a monomer containing a hydrophilic group, etc. It can be mentioned. As the monomer (b ′) containing these polar groups, one type may be used alone, or two or more types may be used in combination.
Among the monomers (b ′) containing these polar groups, a monomer containing a lactone skeleton and a monomer containing a hydrophilic group can be formed because it enables resist pattern formation to be exposed to light with a wavelength of 250 nm or less. Is preferred.

<Monomer containing lactone skeleton (b1)>
The monomer (b1) containing a lactone skeleton may be a compound having a lactone skeleton and a polymerizable functional group, and examples thereof include known monomers.

Examples of the lactone skeleton include a 4- to 20-membered lactone skeleton and the like. The lactone skeleton may be a single ring of only a lactone ring, or an aliphatic or aromatic carbocyclic or heterocyclic ring may be fused to the lactone ring.

As the monomer (b1) containing a lactone skeleton, for example, (meth) acrylic acid ester having a substituted or unsubstituted δ-valerolactone ring, (meth) acrylic acid having a substituted or unsubstituted γ-butyrolactone ring Ester etc. are mentioned. One of these monomers (b1) containing a lactone skeleton may be used alone, or two or more thereof may be used in combination.
Among the monomers (b1) containing such a lactone skeleton, (meth) acrylic acid ester having a substituted or unsubstituted δ-valerolactone ring, substituted or unsubstituted, because of excellent adhesion to a substrate or the like (Meth) acrylic esters having a γ-butyrolactone ring are preferred,
More preferred are (meth) acrylic esters having an unsubstituted γ-butyrolactone ring.

Specific examples of the monomer (b1) containing a lactone skeleton include, for example, β- (meth) acryloyloxy-β-methyl-δ-valerolactone, 4,4-dimethyl-2-methylene-γ-
Butyrolactone, β- (meth) acryloyloxy-γ-butyrolactone, β- (meth)
Acryloyl oxy-β-methyl-γ-butyrolactone, α- (meth) acryloyloxy-γ-butyrolactone, 2- (1- (meth) acryloyloxy) ethyl-4-butanolide, (meth) acrylic acid pantoyl lactone, 5 -(Meth) acryloyloxy-2,
6-norbornane carbolactone, 8-methacryloxy-4-oxatricyclo [5.2
. 1.02,6] decane-3-one, 9-methacryloxy-4-oxatricyclo [5.
2.1.0 ^2,6 ] decane-3-one etc. are mentioned. Moreover, (meth) acryloyloxy succinic acid anhydride etc. are also mentioned as a monomer which has a similar structure. One of these monomers (b1) containing a lactone skeleton may be used alone, or two or more thereof may be used in combination.
Among the monomers (b1) containing such a lactone skeleton, α- (meth) acryloyloxy-γ-butyrolactone and 5-methacryloyloxy-2,6-norbornane carbolactone are excellent because of their excellent adhesion to substrates and the like. 8-methacryloxy-4-oxatricyclo [5.2.1.02,6] decane-3-one is preferable, and α- (meth) acryloyloxy-γ-butyrolactone is more preferable.

<Monomer containing a hydrophilic group (b2)>
The monomer (b2) containing a hydrophilic group may be a compound having a hydrophilic group and a polymerizable functional group, and examples thereof include known monomers.

In the present specification, the hydrophilic group is at least one of a hydroxyl group, a cyano group, an alkoxy group, an amino group and a carboxyl group. These hydrophilic groups are, for example, —C (CF)
₃ ) As in _2- OH, part or all of hydrogen atoms may be substituted by fluorine atoms.
Among these hydrophilic groups, a hydroxyl group and a cyano group are preferable in order to enable formation of a resist pattern to be exposed to light having a wavelength of 250 nm or less.

As a monomer (b2) containing a hydrophilic group, for example, it has a terminal hydroxy group (meth)
Acrylic acid ester; (meth) acrylic acid ester in which hydrogen of hydroxyl group is substituted with alkyl group; monomer having cyclic hydrocarbon group (eg, cyclohexyl (meth) acrylate,
(Meth) acrylic acid-1-isobornyl, (meth) acrylic acid adamantyl, (meth) acrylic acid tricyclodecanyl, (meth) acrylic acid dicyclopentyl, (meth) acrylic acid-2-methyl-2-adamantyl ( Meta) 2-ethyl-2-adamantyl acrylate etc. ) Has a hydrophilic group such as a hydroxyl group or a carboxyl group as a substituent (meth)
Acrylic acid ester etc. are mentioned. As the monomers (b2) containing these hydrophilic groups, one type may be used alone, or two or more types may be used in combination.

As a specific example of the monomer (b2) containing a hydrophilic group, for example, (meth) acrylic acid-2-
Hydroxyethyl, 3-hydroxypropyl (meth) acrylate, 2-hydroxy-n-propyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxyadamantyl (meth) acrylate, 2-Cyano-5-norbornyl (meth) acrylate, 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-
2-adamantyl (meth) acrylate, (meth) acrylic acid, etc. are mentioned. As the monomers (b2) containing these hydrophilic groups, one type may be used alone, or two or more types may be used in combination.
Among the monomers (b2) containing these hydrophilic groups, from the viewpoint of excellent adhesion to a substrate etc., (meth) acrylate 3-hydroxyadamantyl, 2-cyano-5-norbornyl (meth) acrylate
Meta) acrylate, 3-cyano-5-norbornyl (meth) acrylate and 2-cyanomethyl-2-adamantyl (meth) acrylate are preferable, and 3-hydroxyadamantyl methacrylate and 2-cyanomethyl-2-adamantyl methacrylate are more preferable.

<Polymerization initiator (c)>
In the method for producing a copolymer for lithography of the present invention, a polymerization initiator (c) is supplied, and a monomer (a) containing an acid leaving group and a monomer not containing an acid leaving group (b) And copolymerize.

The polymerization initiator (c) is a monomer (a) containing a leaving group and a monomer (b not containing an acid leaving group)
What is necessary is just to copolymerize with, and a well-known polymerization initiator is mentioned.

As a polymerization initiator (c), a thermal polymerization initiator, a photoinitiator, etc. are mentioned, for example. One of these polymerization initiators (c) may be used alone, or two or more thereof may be used in combination.
Among these polymerization initiators (c), a thermal polymerization initiator is preferable because it is suitable for solution polymerization.

The thermal polymerization initiator preferably has a 10-hour half-life temperature not higher than the polymerization temperature, and more preferably a 10-hour half-life temperature of 50 to 70 ° C., because radicals are efficiently generated. The polymerization temperature will be described later.

As a thermal polymerization initiator, for example, 2,2′-azobisisobutyronitrile, dimethyl-
Azo such as 2,2′-azobisisobutyrate, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) propane], etc. Compounds; organic peroxides such as 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane, di (4-tert-butylcyclohexyl) peroxydicarbonate, and the like can be mentioned. One of these thermal polymerization initiators may be used alone, or two or more thereof may be used in combination.
Among these thermal polymerization initiators, azo compounds are preferable because they are excellent in polymerization efficiency.

The polymerization initiator (c) is commercially available. As a commercial item of the polymerization initiator (c), for example, V601 (manufactured by Wako Pure Chemical Industries, Ltd., dimethyl-2,2'-azobisisobutyrate), V65 (manufactured by Wako Pure Chemical Industries, Ltd.), 2,2'-azobis (2,4-dimethyl valeronitrile)) etc. are mentioned.

<Polymerization conditions>
The polymerization temperature can be appropriately set depending on the kind of the monomer (a) containing a leaving group, the monomer (b) not containing an acid leaving group, the kind of the polymerization initiator (c), etc. In order to be excellent, a 10-hour half-life temperature or higher of the polymerization initiator (c) is preferable, and 50 to 150 ° C. is more preferable.

The polymerization method may be a known polymerization method as long as the monomer (a) containing a leaving group and the monomer (b) not containing an acid leaving group are copolymerized.

Examples of the polymerization method include solution polymerization, suspension polymerization, emulsion polymerization and the like.
Among these polymerization methods, solution polymerization is preferable because polymerization control is easy.

The solvent for solution polymerization may be any known solvent as long as the resulting copolymer for lithography is dissolved.

As a solvent for solution polymerization, for example, ethers such as chain ether (for example, diethyl ether, propylene glycol monomethyl ether and the like), cyclic ether (for example, tetrahydrofuran, 1,4-dioxane and the like); methyl acetate, acetic acid Esters such as ethyl, butyl acetate, ethyl lactate, butyl lactate, propylene glycol monomethyl ether acetate, γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; N, N-dimethylacetamide, N, N-dimethylformamide Amides such as: sulfoxides such as dimethyl sulfoxide; aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as hexane; and alicyclic hydrocarbons such as cyclohexane. One of these solvents for solution polymerization may be used alone, or two or more thereof may be used in combination.

The concentration of the solution polymerization is preferably 20 to 40% of the copolymer for lithography obtained in 100% by mass of the solution because the concentration of the solution polymerization is excellent.

<Supply of polymerization initiator (c)>
The method for producing a copolymer for lithography according to the present invention comprises 5 to 30% by mass of the total supply amount of the polymerization initiator (c) during the polymerization reaction period of the initial 5% of the polymerization reaction period from the polymerization start to the polymerization end. Feed into the reactor.

In the present specification, the polymerization reaction period represents the period from the start of polymerization to the end of polymerization.
In the present specification, the initiation of polymerization refers to the time when the supply of the polymerization initiator (c) to the reactor is started.
In the present specification, the end of polymerization represents the time when the execution of the termination operation to the polymerization reaction is started.
Examples of the operation for stopping the polymerization reaction include an operation for stopping heating to the reactor, an operation for cooling the reactor, an operation for adding oxygen or a radio scavenger to the reactor, and the like.

The supply amount of the polymerization initiator (c) in the polymerization reaction period of the initial 5% of the polymerization reaction period is 10 in total supply amount.
It is 5-30 mass% in 0 mass%, 10-25 mass% is preferable, and 15-20 mass% is more preferable.
When the supply amount of the polymerization initiator (c) during the polymerization reaction period of the initial 5% of the polymerization reaction period is 5% by mass or more, the formation of the high molecular weight component can be suppressed. The copolymer for lithography which has a desired molecular weight and molecular weight distribution as the supply amount of the polymerization initiator (c) in the polymerization reaction period of the initial stage 5% of a polymerization reaction period is 30 mass% or less can be obtained.

The total supply amount of the polymerization initiator (c) can be appropriately set according to the type of the polymerization initiator (c) and the weight average molecular weight of the lithography copolymer to be obtained, but it has a desired molecular weight and molecular weight distribution. Since a copolymer for lithography can be obtained, the total supply amount of monomers is 100.
1-25 mol% is preferable with respect to mol%, and 1.5-20 mol% is more preferable.

<Supply of chain transfer agent (d)>
In the method for producing a copolymer for lithography of the present invention, a chain transfer agent (d) may be supplied into the reactor, if necessary. By supplying the chain transfer agent (d), a copolymer for lithography having a desired molecular weight and molecular weight distribution can be obtained.

Examples of the chain transfer agent (d) include thiocarbonyl compounds such as the following chain transfer agents (d1) and (d9), and the like. One of these chain transfer agents (d) may be used alone, or two or more thereof may be used in combination.
Among these chain transfer agents (d), the following chain transfer agents (d1) to (d9) are preferred because they are easy to obtain and excellent in polymerization controllability and reactivity, and the following chain transfer agents (d3), The following chain transfer agent (d4) is more preferred.

What each alphabet in chain transfer agents (d1) to (d9) represents is shown below.
Ar represents an aromatic group or a substituted aromatic group. The substituent represents a halogen atom, a hydroxyl group, an alkoxy group, an amino group, a nitro group, a cyano group, a carbonyl-containing group represented by CORa, a sulfonyl group or a trifluoromethyl group. Ra is an alkyl group having 1 to 8 carbon atoms , An aryl group, an alkoxy group having 1 to 8 carbon atoms, or an aryloxy group.
When a plurality of Ar is present in one molecule, the plurality of Ar may be the same or different.

The total supply amount of the chain transfer agent (d) can be appropriately set according to the type of the chain transfer agent (d) and the weight average molecular weight of the copolymer for lithography to be obtained, but it has a desired molecular weight and molecular weight distribution Since a copolymer for lithography can be obtained, the total supply amount of monomers is 100.
0.001-20 mol% is preferable with respect to mol%, and 0.01-10 mol% is more preferable.

<Copolymer for lithography>
The copolymer for lithography obtained by the method for producing a copolymer for lithography of the present invention has N (v1) / Nave of 1.01 to 1.20.

In the present specification, N (v1) is an elution curve obtained by GPC, among the five fractions obtained by dividing the elution solution showing a peak related to the copolymer for lithography in the elution order so that the volumes become even, Ratio (mol%) of monomer units (A) containing an acid-eliminating group among all monomer units constituting the copolymer contained in the first fraction eluted most
Represents
In the present specification, Nave is obtained by dividing the elution solution showing a peak related to the copolymer for lithography in the elution order so as to equalize the volume in the elution curve obtained by GPC.
It represents the ratio (mol%) of the monomer units (A) containing an acid leaving group among all the monomer units constituting the copolymer contained in the sum of the individual fractions.

FIG. 1 is an explanatory view of the elution curve obtained by GPC.
The abscissa represents the elution volume V (the cumulative value of the eluent flowing out of the column and passing through the detector)
Elution rate x elution time) is shown.
The vertical axis represents the signal strength detected as it passes through the detector.
Generally, when measuring the molecular weight distribution of a copolymer using GPC, as the elution volume V increases, the logarithm of the molecular weight of the copolymer in the eluent passing through the detector monotonously decreases.
That is, the higher the molecular weight, the faster the elution from the column. Also, the signal strength is proportional to the amount of copolymer present in the eluent passing through the detector.

The peak of the elution curve represents from the peak start (point indicated by Ps in FIG. 1) to the peak end (point indicated by Pe in FIG. 1) of the signal intensity in the elution curve. A line connecting the peak start Ps and the peak end Pe is taken as a baseline B.

The fractions represent each of the eluate showing the peak of the elution curve divided into five pieces in the order of elution such that the volume of the eluate becomes uniform. That is, as shown by the broken line in FIG. 1, the volume of the eluent from the peak start Ps to the peak end Pe is divided equally into five volumes (V1 in FIG. 1).
Partition the first fraction in the order of elution of the eluent.
Between V1 and V2 in FIG. 1), the second fraction is fraction 2 (V2 to V in FIG. 1)
3), the third fraction is fraction 3 (between V3 and V4 in FIG. 1), the fourth fraction is fraction 4 (between V4 and V5 in FIG. 1), the fifth fraction is fraction 5 (Between V5 and V6 in FIG. 1).

The ratio N (v1) of the monomer units (A) containing an acid leaving group among all monomer units constituting the copolymer contained in the first fraction (fraction 1) It can be calculated by fractionating the corresponding eluent and measuring by ¹ H-NMR (nuclear magnetic resonance). N (v1) is the average value in fraction 1. When two or more types of monomer units (A) containing an acid leaving group are present, the total of their ratios in the copolymer composition is N (v (v)
1)
The ratio N (v2) to N (v5) of the monomer units (A) containing an acid leaving group out of all the monomer units constituting the copolymer contained in fraction 2 to fraction 5 is a fraction Similar to 1, it can be calculated respectively.
In GPC, the higher the molecular weight, the faster the elution from the column.
Among the above, the weight average molecular weight of the copolymer contained in fraction 1 is the highest.

The ratio Nave of the monomer units (A) containing an acid-eliminating group to all monomer units constituting the copolymer contained in the total of five fractions (fraction 1 to fraction 5) It is an average value in the whole polymerization. When two or more types of monomer units (A) containing an acid leaving group are present, the total of their ratio in the copolymerization composition is Nave.

N (v1) / Nave is 1.01 to 1.20, preferably 1.01 to 1.09.
The fact that N (v1) / Nave is 1.01 to 1.20 means that the ratio of monomer units (A) containing an acid leaving group in the copolymer composition is included in fraction 1 having a high molecular weight. In the copolymer, it means that it is slightly higher than the entire copolymerization.

In general, since the copolymer has a molecular weight distribution, the solubility in a solvent is not uniform, and when used in a resist composition, there is a component which tends to have insufficient solubility in a developer.
In the copolymer containing the monomer unit (A) containing an acid leaving group, the solubility in a solvent such as a developing solution is determined by the molecular weight of the copolymer and the acid leaving group in the copolymer chain. It depends on the amount of the monomer units (A) (components whose bond is cleaved by acid to increase the solubility).

Regarding the molecular weight of the copolymer, when the ratio of the monomer unit (A) containing an acid leaving group in the copolymer is the same, the higher the molecular weight of the copolymer, the slower the dissolution rate in the solvent becomes. The lower the molecular weight of the copolymer, the faster the dissolution rate in the solvent.

With regard to the amount of the monomer unit (A) containing an acid leaving group in the copolymer chain, the acid leaving group is a resist solvent of the copolymer chain or a negative type in a state where the bond is not cleaved by an acid. The dissolution rate in an organic solvent such as a developing solution is improved, and the bond is cleaved by an acid, whereby the dissolution rate in an alkaline aqueous solution such as a positive developing solution is improved. Therefore, when the molecular weight of the copolymer is the same, the higher the ratio of the monomer units (A) containing an acid leaving group, the higher the dissolution rate in the developer, and the monomer containing an acid leaving group The lower the proportion of units (A), the slower the dissolution rate in the developer.

The copolymer for lithography in which N (v1) / Nave is 1.01 or more is a single molecule containing an acid leaving group in the molecular chain of the copolymer contained in fraction 1 having a high molecular weight among fractions 1 to 5. A large amount of monomeric units (A) is contained.
Therefore, in the high molecular weight polymer among the copolymers, the slow dissolution rate due to the high molecular weight is the fast dissolution rate due to the high proportion of the monomer unit (A) containing the acid-eliminable group Thus, the solubility of the high molecular weight copolymer is selectively improved. As a result, the solubility of the copolymer as a whole in the solvent is improved.

On the other hand, in the case where the molecular chain of the copolymer contained in fraction 1 having a high molecular weight contains a large amount of monomer units (A) containing an acid leaving group, a high molecular weight copolymer of copolymer Since the dissolution rate in the solvent is too fast, the overall solubility in the solvent of the copolymer tends to be nonuniform.
The copolymer for lithography having N (v1) / Nave of 1.20 or less has a monomer unit (A) containing an acid-eliminating group in the molecular chain of the copolymer contained in Ruction 1 having a high molecular weight. It is possible to suppress the heterogeneity of the solubility in the solvent due to being contained in excess, and the solubility in the solvent as a whole of the copolymer is improved.

The weight average molecular weight of the copolymer for lithography obtained by the production method of the present invention is 10
00-100,000 are preferable and 3000-30000 are more preferable. When the weight average molecular weight of the copolymer for lithography is 1,000 or more, the coating film performance is excellent. In addition, when the weight average molecular weight of the copolymer for lithography is 100,000 or less, the solubility in a solvent or alkaline developer used in forming a coating film is excellent.

Since the molecular weight distribution of the copolymer for lithography is excellent in lithography performance, 1
. 0-3.0 are preferable, 1.05-2.5 are more preferable, and 1.1-1.7 are further more preferable.

Since the content of the monomer unit (A) containing an acid-eliminating group in the copolymer for lithography is excellent in the sensitivity and resolution of the resist, all the monomer units 100 constituting the copolymer for lithography 20-60 mol% is preferable in mol%, 25-55 mol% is more preferable, 35
More preferably, it is 50 mol%.

Since the content of the monomer unit (B) not containing an acid leaving group in the copolymer for lithography is excellent in the sensitivity and resolution of the resist, all the monomer units constituting the copolymer for lithography 40-80 mol% is preferable in 100 mol%, 45-75 mol% is more preferable,
50 to 65 mol% is more preferable.

When the copolymer for lithography contains a monomer unit (B1) containing a lactone skeleton, the content of the monomer unit (B1) containing a lactone skeleton in the copolymer for lithography is the adhesion to the substrate etc. 20 to 60 mol% is preferable in 100 mol% of all the monomer units which comprise the copolymer for lithography, 25 to 55 mol% is more preferable, and 35 to 50 mol% is still more preferable.

When the copolymer for lithography contains a monomer unit (B2) containing a hydrophilic group, the content of the monomer unit (B2) containing a hydrophilic group in the copolymer for lithography is a rectangle of the resist pattern From the viewpoint of excellent properties, 5 to 30 mol% is preferable, 10 to 25 mol% is more preferable, and 15 to 20 mol% is still more preferable.

<Supply of solution>
In order to obtain the copolymer for lithography as described above, the composition of the copolymer for lithography can be controlled as desired, and therefore, as a supply port for the monomer etc. into the reactor, solution Sa, solution Tb It is preferable to have the supply port which can supply a polymerization initiator (c) solution etc. The supply port may be singular or plural.

The solution Sa is a solution containing a monomer and a solvent. In addition to monomers and solvents, the solution Sa
A polymerization initiator (c) and a chain transfer agent (d) may be included.
a represents 1 to d.
d represents an integer of 1 or more.

The solution Tb is a solution containing a monomer and a solvent. In addition to monomers and solvents, solution Tb
A polymerization initiator (c) and a chain transfer agent (d) may be included.
b represents 1 to e.
e represents an integer of 1 or more.

<Supply of solution Sa>
The solution Sa (hereinafter sometimes simply referred to as "Sa") is only one solution (only S1).
Or two or more solutions (S1, S2,..., Sd).
When two or more solutions are used as the solution Sa, the monomer composition ratio (mol%) of the solution Sa is
It becomes the monomer composition ratio (mol%) which totaled solution S1-solution Sd.
2-5 are preferable and 2-4 are more preferable. It can be controlled to a desired copolymer composition for lithography as d is 2 or more. Moreover, the complexity of a superposition | polymerization process can be suppressed as d is 5 or less.

Each monomer composition ratio of solution S1-solution Sd may mutually be the same, and may differ. Further, each monomer composition ratio of solution S1 to solution Sd may be the same as a monomer composition ratio (hereinafter referred to as “target composition ratio”) for constituting a copolymer for lithography to be obtained. , May be different.
The monomer composition ratio of the solution Sa is preferably designed in consideration of the target composition ratio and the reactivity of each monomer.

The solution Sa may be previously supplied into the reactor, may be gradually supplied into the reactor by dropping or the like, or these supply methods may be used in combination.
Since the solution Sa can contain a large amount of monomer units (A) containing an acid leaving group in the molecular chain of the copolymer contained in fraction 1 having a high molecular weight, the entire amount of the solution Sa is initially obtained in the polymerization step. Preferably, it is fed into the reactor. Specifically, the period during which the entire amount of the solution Sa is supplied into the reactor is preferably within the initial 20% of the monomer supply period, more preferably within the initial 15% of the monomer supply period, and the monomer supply An initial 10% or less of the period is more preferred.
In addition, the whole amount of the solution Sa may be supplied into the reactor at the initial 0% of the monomer supply period.
That is, the entire amount of the solution Sa may be supplied into the reactor before the start of polymerization.
The monomer supply period represents the period from the start of polymerization to the end of the monomer supply.

<Supply of solution Tb>
The solution Tb (hereinafter sometimes simply referred to as "Tb") is only one solution (only T1).
Or two or more solutions (T1, T2,..., Te).
When two or more solutions are used as the solution Tb, the monomer composition ratio (mol%) of the solution Tb is
It becomes the monomer composition ratio (mol%) which totaled solution T1-solution Te.
2-5 are preferable and 2-4 are more preferable. It can be controlled to a desired copolymer composition for lithography as e is 2 or more. Moreover, the complexity of a superposition | polymerization process can be suppressed as e is 5 or less.

The respective monomer composition ratios of the solution T1 to the solution Te may be identical to or different from each other, but are preferably identical to each other because they can be controlled to a desired copolymer composition for lithography. Further, each monomer composition ratio of the solution T1 to the solution Te may be the same as or different from the target composition ratio, but since it can be controlled to a desired copolymer composition for lithography, the target composition ratio and Preferably they are identical.

Since the monomer composition ratio of the solution Tb can approach the desired copolymer composition for lithography, it is preferable that the error be within 10% with respect to the target composition ratio, and 5% with respect to the target composition ratio It is more preferable that the error be within the range, and it is further preferable to design the same as the target composition ratio.

Since the solution Tb can be controlled to the desired copolymer composition for lithography,
It is preferable to gradually feed into the reactor by dropwise addition.

The quantitative ratio of the solution Sa to the solution Tb can be close to the desired copolymer composition for lithography, so that 0.1 to 50 mole% of the solution Sa in 100 mole% of the total amount of monomers, the solution Tb
Is preferably 50 to 99.9 mol%, the solution Sa is 0.3 to 40 mol%, and the solution Tb is 60 to 60
99.7 mol% is more preferable, 0.5 to 30 mol% of the solution Sa, and 70 to 99 of the solution Tb
. 5 mol% is more preferred.

<Supply of polymerization initiator (c)>
It is preferable that the polymerization initiator (c) be gradually supplied into the reactor by dropping, since the polymerization initiator (c) can suppress the formation of high molecular weight components.
The polymerization initiator (c) may be contained in the solution Sa or may be contained in the solution Tb, the solution S.
It may be contained in the polymerization initiator (c) solution prepared separately from a and solution Tb, and these may be used together.
When the polymerization initiator (c) is included in the polymerization initiator (c) solution which is prepared separately from the solution Sa and the solution Tb, the supply of the polymerization initiator (c) solution may be performed until the end of the supply of the solution Tb The process may be completed before the end of the supply of the solution Tb, but is preferably completed before the end of the supply of the solution Tb because generation of high molecular weight components can be suppressed.

In order to obtain the copolymer for lithography as described above, since it can be controlled to a desired copolymer composition for lithography, it is referred to as polymerization step (X), polymerization step (Y) or polymerization step (Z). Is preferred.

<Polymerization process>
The polymerization step (X) will be described below.
The entire amount of the solution Sa is previously fed into the reactor. Then, the inside of the reactor is heated to a predetermined polymerization temperature, and a solution Tb containing a polymerization initiator (c) is dropped and supplied into the reactor. At that time, the polymerization initiator (c) may not be contained in the solution Tb, and the solution Tb and the polymerization initiator solution may be supplied in parallel into the reactor. The solution Tb and the polymerization initiator solution are simultaneously started to be supplied, or the polymerization initiator solution is first supplied.

In the polymerization step (X), the period from the start of supply of the polymerization initiator solution to the start of supply of the solution Tb is preferably 0 to 10 minutes because generation of a high molecular weight component can be suppressed.
-3 minutes are more preferable, and 0 minutes are still more preferable.
In the polymerization step (X), the supply rate of the solution Tb and the polymerization initiator solution is preferably constant because a copolymer for lithography having a desired molecular weight and molecular weight distribution can be obtained.
In the polymerization step (X), the supply of the polymerization initiator solution is preferably completed prior to the supply of the solution Tb because generation of high molecular weight components can be suppressed.

The polymerization step (Y) will be described below.
Only the solvent is previously fed into the reactor. Next, the reactor is heated to a predetermined polymerization temperature,
The solution Sa and the solution Tb containing the polymerization initiator (c) are added dropwise into the reactor. that time,
The solution Sa may contain a polymerization initiator (c). The solution Sa and the solution Tb are simultaneously started to be supplied, or the solution Sa is first supplied.

In the polymerization step (Y), the period from the start of supply of the solution Sa to the start of supply of the solution Tb is
From the viewpoint of suppressing the formation of high molecular weight components, 0 to 10 minutes are preferable, 0 to 3 minutes are more preferable, and 0 minutes are even more preferable.
In the polymerization step (Y), the supply rate of the solution Sa and the solution Tb is preferably constant because a copolymer for lithography having a desired molecular weight and molecular weight distribution can be obtained.
In the polymerization step (Y), it is preferable to complete the supply of the solution Sa prior to the supply of the solution Tb because the supply of the solution Sa can be controlled to a desired copolymer composition for lithography.

The polymerization step (Z) will be described below.
A portion of the solution Sa is previously fed into the reactor. Next, the inside of the reactor is heated to a predetermined polymerization temperature, and a solution Tb containing the remainder of the solution Sa and the polymerization initiator (c) is dropped and supplied into the reactor. At that time, the polymerization initiator (c) may be contained in the balance of the solution Sa. The remaining portion of the solution Sa and the solution Tb are simultaneously supplied, or the remaining portion of the solution Sa is first supplied.

In the polymerization step (Z), the period from the start of supply of the remaining portion of the solution Sa to the start of supply of the solution Tb is preferably 0 to 10 minutes because generation of high molecular weight components can be suppressed.
-3 minutes are more preferable, and 0 minutes are still more preferable.
In the polymerization step (Z), the supply rate of the remainder of the solution Sa and the solution Tb is preferably constant since a copolymer for lithography having a desired molecular weight and molecular weight distribution can be obtained.
In the polymerization step (Z), it is preferable to complete the supply of the solution Sa prior to the supply of the solution Tb because the supply of the remainder of the solution Sa can be controlled to a desired copolymer composition for lithography.

After completion of the polymerization step (X), the polymerization step (Y), and the polymerization step (Z), if necessary, the holding step for holding the inside of the reactor at the polymerization temperature, the cooling step for lowering the temperature in the reactor, the purification step Etc. may be implemented.

Among these polymerization processes, a copolymer for lithography having more desirable molecular weight and molecular weight distribution can be obtained, and the polymerization composition (Z) can be controlled because it can be controlled to a more desirable copolymer composition for lithography. preferable.

<Preparation of Solution Sa>
Hereinafter, a method of setting the monomer composition ratio (mol%) of the solution Sa will be described.

First, the reactor containing only the solvent is heated to a predetermined polymerization temperature, and the target composition ratio α'1: α
A solution containing a monomer mixture having the same composition as that of '2:... Α' n (mol%), a solvent and a polymerization initiator is fed dropwise into the reactor at a constant feed rate. The elapsed time from the start of dripping t1
The composition ratio P1: P2:...: Pn (mol%) of the monomer units generated at tm is calculated.
At this time, P1: P2:...: Pn is an unreacted monomer composition ratio α1 at t1 to tm.
It can be calculated by subtracting from: α 2:... Α n (mol%).
n represents an integer of 2 or more.
m represents an integer of 2 or more.

Then, a time period from tk-1 to tk in which P1: P2:...: Pn is in a constant or nearly constant state (hereinafter, referred to as "stable state") is found. P'1: P'2: ..: P'n (mol%) is calculated for the conversion of monomers from tk-1 to tk.
Usually, when examining the relationship between the elapsed time and the composition ratio of unreacted monomers in the solution, the composition ratio of unreacted monomers fluctuates at the beginning of the polymerization reaction period, and then gradually changes. It becomes smaller and becomes constant or nearly constant. In addition, the composition ratio of unreacted monomers fluctuates again after all of the supplied solution is supplied.
k represents an integer of 2 or more.

Next, the monomer conversion rate P'1: P'2: ... at the elapsed time tk from the start of dropwise addition
: A factor F1 for obtaining a target composition ratio α'1: α'2:...: Α'n from P'n
, F2, ..., Fn are calculated. The factors are F1 = P1 / P'1 and F2, respectively.
= P2 / P'2, ..., Fn = Pn / P'n.

Then, using functions G1, G2, ..., Gn, which are functions of F1, F2, ..., Fn, and target composition ratios α'1: α'2: ...: α 'n The composition ratio (mol%) of the solution S'a is calculated. The target composition ratio α′1: α′2:...: The composition ratio of S′a at α′n
When a1, S'a2, ..., S'an are used, they are calculated by the following equation.
S'a1 = (α'1 / G1) / (α'1 / G1 + α'2 / G2 +... + Α'n / G
n) x 100
S'a2 = (α'2 / G2) / (α'1 / G1 + α'2 / G2 +... + Α'n / G
n) x 100
S'an = (α'n / Gn) / (α'1 / G1 + α'2 / G2 +... + Α'n / G
n) x 100
At this time, the value of the function Gi of the factor Fi can be expressed by N (v1) / N
ave is 1.01 to 1.20.
In the case of the monomer (a) containing an acid leaving group: Gi = Fi / 3
In the case of monomers (a) containing an acid leaving group: Gi = Fi
i represents an integer of 1 or more and n or less.

Each value of the monomer composition ratio (mol%) of the solution Sa can be controlled to a desired copolymer composition for lithography, and thus the composition ratio (mol%) of the ideal solution S'a calculated above 0.75 to 1.25 times of each value is preferable, 0.8 to 1.2 times is more preferable, and 0.9 to 1.
1 × is more preferable.

The copolymer for lithography obtained by the method for producing a copolymer for lithography of the present invention is a copolymer because a monomer unit (A) containing an acid-eliminable group is present in an appropriately large amount on the high molecular weight side. The decrease in the dissolution rate in the solvent due to the high molecular weight of the monomer unit is a monomer unit containing an acid leaving group (A
The increase in the dissolution rate due to the high distribution of the composition in (4) compensates for the solubility in a solvent and improves the uniformity of the dissolution rate.
Therefore, when the copolymer for lithography obtained by the method for manufacturing a copolymer for lithography of the present invention is used for a chemically amplified resist composition, the uniformity of the solubility and dissolution rate in a developer is improved, and high A sensitive chemically amplified resist composition can be obtained.
Further, in the copolymer for lithography obtained by the method for manufacturing a copolymer for lithography of the present invention, the formation of a high molecular weight component is suppressed, and the formation of microgel and the like can be suppressed. When used in the above, it is possible to form a resist film which is excellent in solubility in a resist solvent and excellent in sensitivity.

The copolymer for lithography obtained by the method for manufacturing a copolymer for lithography of the present invention has a small proportion of high molecular weight components, is uniform in solubility in a developer, and improves sensitivity when used in a resist composition. In addition to the resist copolymer used to form a resist film, for example, an antireflective film (TARC) formed on the upper layer of the resist film or an antireflective film (BARC) formed on the lower layer of the resist film. Copolymers for antireflective coatings used in the formation of
It can be suitably used as a copolymer for a gap fill film used for forming a gap fill film, a copolymer for a top coat film used for forming a top coat film, and the like.

The antireflective film copolymer reacts with a curing agent or the like to be cured together with a monomer unit containing a light absorbing group to avoid mixing with the resist film, thereby curing an amino group, an amide group, a hydroxyl group, an epoxy group It is preferable to include a monomer unit containing a reactive functional group such as

The light absorbing group is a group having high absorption performance to light in a wavelength range where the photosensitive component in the resist composition has sensitivity, and examples thereof include phenolic hydroxyl group, anthracene ring, naphthalene ring, benzene ring, quinoline ring, A group having a ring structure (which may have an optional substituent) such as a quinoxaline ring and a thiazole ring, and the like can be mentioned. Among these light absorbing groups, when KrF laser light is used as the irradiation light, an anthracene ring or an anthracene ring having an arbitrary substituent is preferable, and when ArF laser light is used as the irradiation light, the benzene ring is optionally substituted A benzene ring having a group is preferred.

As the optional substituent, for example, alcoholic hydroxyl group, carboxy group, carbonyl group,
An ester group, an amino group, an amido group etc. are mentioned.

As a monomer containing a light absorbable group, a benzyl (meth) acrylate, p-hydroxyphenyl (meth) acrylate etc. are mentioned, for example.

In particular, a polymer for an antireflective film having a protected or non-protected phenolic hydroxyl group as a light absorbing group is preferable from the viewpoint of good developability and high resolution.

<Method of Producing Resist Composition>
The method for producing a resist composition according to the present invention comprises the copolymer obtained by the method for producing a copolymer for lithography according to the present invention, and a compound capable of generating an acid upon irradiation with active energy rays or radiation (
Hereinafter, it is referred to as "photoacid generator". It is preferable to include the step of mixing

The method for producing a resist composition according to the present invention comprises a copolymer for lithography and a photoacid generator,
It is preferable to dissolve in a resist solvent and mix.
As a resist solvent, the solvent of the solution polymerization mentioned above etc. are mentioned, for example.
The resist composition may be a solution in which a copolymer for lithography and a photoacid generator are dissolved in a resist solvent, or may be a filtrate after filtration, and the copolymer for lithography and a photoacid generator are dissolved in a resist solvent The concentrated solution may be concentrated, and the filtrate may be filtered thereafter. Such a resist composition is a chemically amplified resist composition.

<Photo acid generator>
The photoacid generator may be any compound that can be used as a chemically amplified resist composition, and examples thereof include known photoacid generators.

As a photo-acid generator, an onium salt compound, a sulfone imide compound, a sulfone compound, a sulfonate ester compound, a quinone diazide compound, a diazomethane compound etc. are mentioned, for example. One of these photoacid generators may be used alone, or two or more thereof may be used in combination.

The content of the photoacid generator is 0.1 to 2 with respect to 100 parts by mass of the copolymer for lithography
0 mass part is preferable and 0.5-10 mass parts is more preferable.

<Nitrogen compounds>
The resist composition may further contain a nitrogen compound, if necessary, in addition to the copolymer for lithography, the photoacid generator, and the resist solvent. By including a nitrogen compound in the resist composition, the resist pattern shape, the stability over time of placement, etc. are improved. That is, the cross-sectional shape of the resist pattern becomes closer to a rectangle. In addition, in a mass production line of semiconductor devices, the resist film may be irradiated with light and then baked (PEB) and then left for several hours until the next development processing, but such standing (over time Generation of deterioration of the cross-sectional shape of the resist pattern due to

As a nitrogen compound, amine compounds, such as a secondary amine compound and a tertiary amine compound, etc. are mentioned, for example. One of these nitrogen compounds may be used, or two or more thereof may be used in combination. Among these nitrogen compounds, amine compounds are preferable, and secondary lower aliphatic amines and tertiary lower aliphatic amines are more preferable.

The content of the nitrogen compound is 0.01 to 100 parts by mass of the copolymer for lithography.
2 parts by mass is preferred.

<Acid compound>
As the resist composition, in addition to a copolymer for lithography, a photoacid generator, a nitrogen compound, and a resist solvent, if necessary, an organic carboxylic acid, an oxo acid of phosphorus or a derivative thereof (hereinafter referred to as
It is called an "acid compound". May be included. By including the acid compound in the resist composition, it is possible to suppress the sensitivity deterioration due to the compounding of the nitrogen compound, and the resist pattern shape, the stability over time of placing, etc. are improved.

Examples of the organic carboxylic acid include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like. One of these organic carboxylic acids may be used alone, or two or more thereof may be used in combination.

Examples of phosphorus oxo acids or derivatives thereof include phosphoric acid or derivatives thereof, phosphonic acid or derivatives thereof, phosphinic acid or derivatives thereof, and the like. One of these phosphorus oxo acids or their derivatives may be used alone, or two or more of them may be used in combination.

The content of the acid compound is 0.01 to 5 with respect to 100 parts by mass of the copolymer for lithography
Parts by weight are preferred.

<Various additives>
The resist composition may further contain a copolymer for lithography, a photoacid generator, a nitrogen compound, an acid compound, a surfactant, other quenchers, a sensitizer, as needed, in addition to the resist solvent.
Various additives such as antihalation agents, storage stabilizers, antifoaming agents and the like may be included.

As various additives, known additives in the field of copolymers for lithography can be used.
The content of various additives may be determined appropriately according to the characteristics.

<Application of Resist Composition>
The resist composition obtained by the method for producing a resist composition according to the present invention has excellent solubility in a resist solvent and can form a resist film excellent in sensitivity, so it should be suitably used for a substrate on which a pattern is formed. it can.

<Method of Manufacturing Substrate Having Pattern Formed>
The method for producing a substrate provided with the pattern of the present invention comprises the steps of: applying a resist composition obtained by the method of producing a resist composition of the present invention on a substrate to be processed; It is preferable to include the process and the process developed using a developing solution.

As a method of applying a resist composition on a substrate to be processed, for example, a resist composition is applied by spin coating or the like on a surface to be processed of a substrate such as a silicon wafer to form a desired pattern. Baking treatment (pre-baking) of the substrate coated with the object
The method of forming a resist film on a board | substrate etc. are mentioned by drying by etc., etc. are mentioned.

In the exposure with light of a wavelength of 250 nm or less, the resist film on the substrate is preferably exposed through a photomask to form a latent image.
The exposure light may be light having a wavelength of 250 nm or less, and examples thereof include KrF excimer laser, ArF excimer laser, F2 excimer laser, EUV light, electron beam and the like. Among these exposure light, KrF excimer laser, ArF excimer laser, F
2 Excimer laser and EUV light are preferable, and ArF excimer laser is more preferable.

Immersion exposure in which light is irradiated in a state in which a high refractive index liquid such as pure water, perfluoro-2-butyltetrahydrofuran or perfluorotrialkylamine is interposed between the resist film and the final lens of the exposure apparatus You may go.

<Development>
After exposure, a development process is performed to form a pattern.
As a developing method, for example, a method of dissolving a part of a resist film on a substrate and appropriately washing (rinsing) the substrate with pure water or the like can be mentioned.

The development system may be either positive or negative.
In the case of the positive type, the resist film in the exposed area is dissolved.
In the case of the negative type, the resist film other than the exposed area is dissolved.

As a developing method, for example, a method of immersing a substrate in a bath filled with a developer for a predetermined time (
Dipping method), developing method by raising developer on the substrate surface by surface tension and standing still for a fixed time (paddle method), method of spraying developer on substrate surface (spray method), rotating at a constant speed The method (dynamic dispensing method) etc. which continue a developing solution while scanning a developing solution application | coating nozzle on a board | substrate at fixed speed are mentioned.

<Developer>
When positive development is performed, it is preferable to use an alkaline developing solution as a developing solution, and it is more preferable to use an alkaline aqueous solution.

Examples of the alkaline aqueous solution used for positive development include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia and the like; primary ones such as ethylamine and n-propylamine Amines; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; tetramethylammonium hydroxide and tetraethylamine Examples thereof include quaternary ammonium salts such as ammonium hydroxide; and aqueous solutions of alkaline compounds such as cyclic amines such as pyrrole and piheridine. The alkaline aqueous solution used for these positive developments is 1
The species may be used alone, or two or more species may be used in combination.

The cleaning liquid after the positive development may be pure water, or may be pure water to which an appropriate amount of surfactant is added.

  When negative development is performed, it is preferable to use an organic solvent as a developer.

Examples of the organic solvent used for negative development include ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as methyl acetate, butyl acetate, ethyl acetate and propylene glycol monomethyl ether acetate; methyl alcohol, ethyl alcohol, isopropyl alcohol, Alcohol solvents such as 1-methoxy-2-propanol; hydrocarbon solvents such as toluene, xylene, pentane, hexane, heptane and the like can be mentioned. The organic solvents used for these negative developments may be used alone or in combination of two or more.

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

The copolymer for lithography obtained by the method for manufacturing a copolymer for lithography according to the present invention has a small proportion of high molecular weight components, uniform solubility in a developer, and sensitivity when used in a resist composition. It can improve. Therefore, dissolution of the copolymer for lithography in a resist solvent at the time of preparation of a resist composition can be carried out easily and favorably.

The resist composition obtained by the method for producing a resist composition according to the present invention has excellent solubility in an alkaline developer, so that the sensitivity is improved and the amount of insoluble matter in the resist composition is small. In the formation, defects due to insolubles are less likely to occur. In addition, the resist composition obtained by the method for producing a resist composition of the present invention is required to use an exposure light having a wavelength of 250 nm or less (for example, a wavelength 193
It can use suitably for pattern formation in the photolithography or electron beam lithography using the irradiation light by ArF excimer laser of nm.
In addition, when manufacturing the resist composition used for photolithography using wavelength 250 nm or less exposure light, a monomer is suitably selected so that the copolymer for lithography may be transparent in the wavelength of exposure light. It is preferred to use.

In the case of a positive resist composition, since the excellent solubility in an alkaline developing solution is obtained, the sensitivity is improved, and since the insoluble content in the resist composition is small, a defect caused by the insoluble content in pattern formation Is less likely to occur.
In the case of a negative resist composition, the sensitivity is improved since excellent solubility in an organic solvent is obtained, and the amount of insoluble matter in the resist composition is small. It is hard to occur.

From the above, the substrate on which the pattern obtained by the method for producing a substrate on which the pattern of the present invention is formed has a defect is small and has a fine pattern with high accuracy.

A substrate having such a fine pattern with few defects and having high accuracy can be suitably used for a semiconductor manufacturing process such as IC; integrated circuit such as personal computer and tablet; liquid crystal display etc.

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. The values of various manufacturing conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and the preferable range is the value of the upper limit or the lower limit described above It may be a range defined by the values of the following examples or a combination of the values of the examples.

(Measurement of weight average molecular weight and molecular weight distribution)
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the copolymer were determined in terms of polystyrene by gel permeation chromatography (GPC) under the following GPC conditions 1.

[GPC condition 1]
Device: High-speed GPC device "HLC-8220GPC" (manufactured by Tosoh Corporation)
Separation column: Three “Shodex GPC K-805L” (Showa Denko KK) connected in series Measurement temperature: 40 ° C.
Eluent: Tetrahydrofuran (THF)
Flow rate: 1 mL / min Injection volume: 0.1 mL
Detector: Differential refractometer “ATAGO RX-5000α” (manufactured by Atago Co., Ltd.)
Sample: In the case of the copolymer itself, about 20 mg of the copolymer is dissolved in 5 mL of THF and filtered with a 0.5 μm membrane filter; in the case of the polymerization reaction solution, about 30 mg of the sampled polymerization reaction solution is 5 mL of THF Dissolved in water and filtered through a 0.5 μm membrane filter

The standard curve was prepared by dissolving about 20 mg of standard polystyrene in 5 mL of THF and
The solution filtered through a membrane filter was used to inject into the separation column under the above-mentioned GPC condition 1 and prepared from the relationship between elution time and molecular weight. As the standard polystyrene, the following standard polystyrene (all manufactured by Tosoh Corporation) was used.
"F-80" (Mw = 706000)
"F-20" (Mw = 190000)
"F-4" (Mw = 37900)
"F-1" (Mw = 10,200)
"A-2500" (Mw = 2630)
"A-500" (mixture of Mw = 682, 578, 474, 370, 260)

(Quantification of monomer)
The amount of unreacted monomer remaining in the polymerization reaction solution was determined by the following method.
0.5 g of a polymerization reaction solution in a reactor was collected, and this was diluted with acetonitrile to make the total volume 50 mL using a measuring flask. The diluted solution is filtered through a 0.2 μm membrane filter, and high performance liquid chromatograph "HPLC-8020" (manufactured by Tosoh Corp.) is used.
The amount of unreacted monomer in the diluted solution was determined for each monomer.

In this measurement, one separation column is “Inertsil ODS-2” (manufactured by GL Sciences Inc.), and the mobile phase is a water / acetonitrile gradient system, flow rate 0.8
mL / min, UV-visible absorptiometer "UV-8020" (made by Tosoh Corp.), detector
The detection wavelength was 220 nm, the measurement temperature was 40 ° C., and the injection amount was 4 μL.
The separation column "Inertsil ODS-2" has a silica gel particle size of 5 μm,
A column having an inner diameter of 4.6 mm and a column length of 450 mm was used.
In addition, the gradient conditions of the mobile phase were as follows, with the solution A being water and the solution B being acetonitrile. In order to quantify the amount of unreacted monomers, three types of monomer solutions having different concentrations were used as standard solutions.
Measurement time 0 to 3 minutes: A liquid / B liquid = 90% by volume / 10% by volume
Measurement time 3 to 24 minutes: A liquid / B liquid = 90% by volume / 10% by volume to 50% by volume /
Up to 50% by volume Measuring time 24 to 36.5 minutes: A liquid / B liquid = 50% by volume / 50% by volume to 0% by volume / 1
00 volume% Measurement time 36.5 to 44 minutes: A liquid / B liquid = 0 volume% / 100 volume%

(Decomposition of copolymer by GPC)
The division of the copolymer was carried out by GPC under the following GPC condition 2. By evaporating the solvent from the solution of each fraction to obtain a solid, a copolymer contained in each fraction was obtained.

[GPC condition 2]
Device: Preparative liquid chromatograph “LC-9105” (Nippon Analytical Industry Co., Ltd.)
Separation column: “JAIGEL-2H” (Nippon Analytical Industry Co., Ltd.) and “JAIGEL-
3 H "(Nippon Analytical Industry Co., Ltd.) connected in series Measurement temperature: 40 ° C
Eluent: THF
Flow rate: 3.5 mL / min Injection volume: 10 mL
Detector: Differential refractometer “ATAGO RX-5000α” (manufactured by Atago Co., Ltd.)
Sample: A solution obtained by dissolving about 1 g of the copolymer in 10 mL of THF and filtering it through a 0.5 μm membrane filter. Separation method: Make the volume of the eluent showing a peak related to the copolymer uniform in the elution curve. 5 fractions in order of elution, and 5 fractions were separated.

(Measurement of copolymer composition)
Each copolymerization composition in five fractions fractionated by the resolution by GPC of the said copolymer was measured by the following method.
The solvent was distilled off from each of the five fractions, and about 5 parts by mass of the obtained solid was dissolved in about 95 parts by mass of heavy dimethyl sulfoxide to prepare a sample solution. This sample solution was placed in an NMR tube, and analyzed using ¹ H-NMR (manufactured by Nippon Denshi Co., Ltd., resonance frequency: 270 MHz). The copolymerization composition of the copolymer was calculated from the integrated intensity ratio of the signal derived from each monomer unit.

(Evaluation of solubility of copolymer)
20 parts by mass of the copolymer and 80 parts by mass of propylene glycol-1-monomethyl ether-2-acetate are mixed and stirred while maintaining at 25 ° C., and after completely judging dissolution by visual observation, the obtained solution is The solution was divided, 55.5 parts by mass of heptane was added to one solution, and 6.96 parts by mass of methanol was added to the other solution, followed by stirring for 15 minutes, and the turbidity at room temperature was measured. The turbidity meter is “Orbeco-Hellige TB200” (Orbeco Hellig
e) was used.
The smaller the turbidity when adding heptane, the better the solubility in low polar solvents such as hydrocarbons, and the smaller the turbidity when adding methanol, the better solubility in high polar solvents such as alcohols. Also, in general, when the turbidity exceeds 10 NTU, it is judged to be cloudy visually.

(Evaluation of sensitivity of resist composition)
The resist composition was spin-coated on a 6-inch silicon wafer and prebaked (PAB) at 120 ° C. for 60 seconds on a hot plate to form a 300 nm-thick resist film. Subsequently, 18 shots of an area of 10 mm × 10 mm were exposed using an ArF excimer laser exposure apparatus “VUVES-4500” (manufactured by Litho Tech Japan Co., Ltd.) while changing the exposure amount. Next, post bake (PEB) is performed at 110 ° C. for 60 seconds, and then using a resist development analyzer “RDA-806” (manufactured by Litho Tech Japan Co., Ltd.) 23
. It developed for 5 seconds in 5 degreeC, 2.38 mass% tetramethylammonium hydroxide aqueous solution. With respect to the resist film of each exposure dose, the temporal change of the resist film thickness during development was measured.
Based on the data of the time-dependent change in resist film thickness obtained, the logarithm of the exposure amount (mJ / cm ² ),
The relationship between the ratio (%) of the remaining film thickness at the time of development for 30 seconds to the initial film thickness (%) (hereinafter referred to as the residual film ratio) was plotted to create an exposure amount-residual film ratio curve. Based on this curve, the value of the required exposure (Eth) for achieving a residual film rate of 0% was determined. That is, the exposure amount (mJ / cm ² ) at the point where the exposure amount-remaining film rate curve intersects with the straight line of the residual film rate 0% was determined as Eth.
The value of Eth represents the sensitivity, and the smaller the value is, the higher the sensitivity is.

Reference Example: Preparation of Solution Sa
As the monomer (a) containing an acid leaving group, 1-ethylcyclohexyl methacrylate (hereinafter referred to as “monomer (1)”) is used as the monomer (b1) containing a lactone skeleton. As α) methacryloyloxy-γ-butyrolactone (hereinafter referred to as “monomer (2)”).
As a monomer (b2) containing a hydrophilic group, 3-hydroxyadamantyl methacrylate (hereinafter, referred to as "monomer (3)") was used.
The target composition ratio is α′1 (monomer (1)): α′2 (monomer (2)): α′3 (monomer
3)) = 40: 40: 20 (mol%).
The polymerization initiator (c) is dimethyl-2,2′-azobisisobutyrate (trade name “V60
1 ", Wako Pure Chemical Industries, Ltd.) was used.
The target value of the weight average molecular weight was 10000.
The polymerization temperature was 80.degree.

Flask equipped with nitrogen inlet, stirrer, condenser, dropping funnel and thermometer (reactor)
The inside was under a nitrogen atmosphere, and 67.8 parts by mass of ethyl lactate was supplied. Put the flask in a water bath,
The temperature in the flask was heated to 80 ° C. while stirring in the flask.
Then, a solution obtained by mixing the following compounds was dropped into the flask at a constant dropping rate over 4 hours by a dropping funnel, and the temperature in the flask was further kept at 80 ° C. for 3 hours.
Monomer (1) 32.93 parts by mass (40 mol%)
Monomer (2) 28.56 parts by mass (40 mol%)
Monomer (3) 19.82 parts by mass (20 mol%)
2.415 parts by mass of dimethyl-2,2'-azobisisobutyrate (2.5 mol% with respect to the total supply of monomers)
Subsequently, 122.0 parts by mass of ethyl lactate was cooled to 25 ° C. to stop the reaction.

0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours from the start of dropwise addition of the above mixed solution
After 6 hours and 7 hours, 0.5 g of the solution in the flask was sampled, and the unreacted monomer composition ratio α1: α2: α3 (mol%) remaining in the flask was calculated. In Table 1, the unreacted monomer composition ratio α1: α2 remaining in the flask after 2 hours and 3 hours from the start of dropwise addition
: Α3 (mol%) is shown.

From the unreacted monomer composition ratio α1: α2: α3 (mol%) remaining in the flask shown in Table 1, the composition ratio P1: P2: P3 (mol%) of the produced monomer units was calculated. In Table 2, the composition ratio P1: P2: P3 (mol%) of the produced monomer units after 2 hours and 3 hours after the start of dropwise addition
).

Composition ratio P1: P2 of the monomer units formed 2 hours to 3 hours after the start of dropwise addition:
P3 has become stable. Monomer conversion P'1: P'2: P 'after 3 hours from the start of dropwise addition
It was 38.47: 41.05: 20.48 when 3 (mol%) was computed.

Conversion of monomers 3 hours after the start of dropwise addition P'1: P'2: P'3 = 38.47: 41.
The factors F1, F2, and F3 for obtaining the target composition ratio α′1: α′2: α′3 = 40: 40: 20 were calculated from 05: 20.48.
F1 = P1 / P'1 = 1.27
F2 = P2 / P'2 = 0.76
F3 = P3 / P'3 = 1.22

G1, G2, G3 which is a function of F1, F2, F3, and target composition ratio α'1: α'2: α '
3 = 40: 40: 20, and the composition ratio S'a1: S'a2: S 'of the ideal solution S'a
a3 (mol%) was calculated.
S'a1 = (α'1 / G1) / (α'1 / G1 + α'2 / G2 + α'3 / G3) × 1
00 = 76.7
S'a2 = (α'2 / G2) / (α'1 / G1 + α'2 / G2 + α'3 / G3) × 1
00 = 15.3
S'an = (α'n / Gn) / (α'1 / G1 + α'2 / G2 + α'3 / G3) × 1
00 = 8.0

The following values were used for the functions G1, G2, and G3 of the factors F1, F2, and F3.
G1 = F1 / 3 = 0.25
G2 = F2 = 1.27
G3 = F3 = 1.22

Example 1
The type of monomer, the target composition ratio, the type of polymerization initiator, the target value of the weight average molecular weight, and the polymerization temperature were the same as in the reference example.
Solution S1 was solution Sa calculated in the reference example, solution T1 was the same as the target composition ratio, and a copolymer for lithography was obtained by the polymerization step (Z).

The flask (reactor) equipped with a nitrogen inlet, a stirrer, a condenser, two dropping funnels, and a thermometer was placed under a nitrogen atmosphere, and a solution S1 was supplied. The flask was placed in a water bath and the temperature in the flask was heated to 80 ° C. while stirring in the flask.
Subsequently, supply of the following solution T1 and a polymerization initiator (c) solution is simultaneously started from separate dropping funnels, and constant addition of solution T1 over 4 hours and polymerization initiator (c) solution over 20 minutes is continued. The solution was dropped into the flask at a speed, and after the completion of the supply of the solution T1, the temperature in the flask was maintained at 80 ° C. for 3 hours.
Thereafter, 7 hours after the start of dropwise addition of the solution T1, the reaction was cooled to 25 ° C. to stop the reaction.
The polymerization initiator (c) supplied during the initial 5% polymerization reaction period was 27% by mass of the total supply amount of the polymerization initiator (c).

The following mixed solution was used for solution S1, solution T1, and a polymerization initiator (c) solution.
(Solution S1)
Monomer (1) 9.42 parts by mass (76.7 mol%)
Monomer (2) 1.69 parts by mass (15.3 mol%)
Monomer (3) 1.21 parts by mass (8.0 mol%)
Ethyl lactate 99.3 parts by mass (solution T1)
Monomer (1) 34.30 parts by mass (40 mol%)
29.75 parts by mass (40 mol%) of monomer (2)
Monomer (3) 20.65 parts by mass (20 mol%)
2.119 parts by mass of dimethyl-2,2'-azobisisobutyrate (1.84 mol% based on the total supply of monomers in solution S1 and solution T1)
Ethyl lactate 118.8 parts by mass (polymerization initiator (c) solution)
0.530 parts by mass of dimethyl-2,2'-azobisisobutyrate (0.48 mol% relative to the total supply of monomers in solution S1 and solution T1)
8.3 parts by mass of ethyl lactate

The polymerization reaction solution in the obtained flask was added dropwise with stirring to a mixed solvent of methanol and water (methanol: water = 80: 20 (volume ratio)) of about 10 volumes, and a white solid precipitated.
The white solid was separated by filtration and dropped again into a mixed solvent of about 10 volumes of methanol and water (methanol: water = 80: 20 (volume ratio)) with stirring to wash the white solid. The washed white solid was separated by filtration to obtain 160 parts by mass of wet powder of copolymer (1) for lithography. Ten parts by mass of the wet powder of the obtained copolymer (1) for lithography was dried at 40 ° C. under reduced pressure for about 40 hours to obtain a copolymer (1) for lithography.
Mw, Mw / Mn, N (v1) to N (v5) of the obtained copolymer (1) for lithography
Table 3 shows Nave). Also, the solubility of the obtained copolymer for lithography (1) is shown in Table 4.

The remainder of the wet powder of the copolymer (1) for lithography is dissolved in 880 parts by mass of propylene glycol-1-monomethyl ether-2-acetate, and a nylon filter with a pore diameter of 0.04 μm (trade name “P-NYLON N66 FILTER 0” The solution was filtered through a solution of “04 M”, manufactured by Nippon Pall Co., Ltd. The resulting solution is heated under reduced pressure to distill off methanol and water, partially distilling out propylene glycol-1-monomethyl ether-2-acetate, and the concentration of copolymer (1) for lithography There was obtained a 25% by weight solution. The conditions for evaporation of the solvent were a maximum ultimate vacuum of 0.7 kPa, a maximum solution temperature of 65 ° C., and an evaporation time of 8 hours.
200 parts by mass of a solution containing 25% by mass of the obtained copolymer (1) for lithography, 1 part by mass of triphenylsulfonium triflate as a photoacid generator, and propylene glycol-1-monomethylether-2-acetate 199 The parts by mass were mixed, passed through a membrane filter with a pore size of 0.1 μm, and filtered to obtain a resist composition (1).
The sensitivity of the obtained resist composition (1) is shown in Table 3.

Comparative Example 1
Similar to the reference example, the compositional ratio S′a1: S′a2: S′a3 of the factor ideal solution S′a (
The molar% was calculated. However, it was set as factor F1 = G1 so that a supply rate of monomer (a) containing an acid leaving group becomes fixed.
S'a1 = (α'1 / G1) / (α'1 / G1 + α'2 / G2 + α'3 / G3) × 1
00 = 52.4
S'a2 = (α'2 / G2) / (α'1 / G1 + α'2 / G2 + α'3 / G3) × 1
00 = 31.3
S'an = (α'n / Gn) / (α'1 / G1 + α'2 / G2 + α'3 / G3) × 1
00 = 16.3

The following mixed solution was used for solution S1, solution T1, and a polymerization initiator (c) solution.
(Solution S1)
7.68 mass parts (52.4 mol%) of monomers (1)
Monomer (2) 3.99 parts by mass (31.3 mol%)
2.88 mass parts (16.3 mol%) of monomers (3)
Ethyl lactate 99.3 parts by mass (solution T1)
Monomer (1) 27.71 parts by mass (40 mol%)
Monomer (2) 24.03 parts by mass (40 mol%)
16.68 parts by mass (20 mol%) of monomer (3)
0.690 parts by mass of dimethyl-2,2′-azobisisobutyrate (0.70 mol% based on the total supply of monomers in solution S1 and solution T1)
Ethyl lactate 101.8 parts by mass (polymerization initiator (c) solution)
1.280 parts by mass of dimethyl-2,2'-azobisisobutyrate (1.30 mol% relative to the total supply of monomers in solution S1 and solution T1)
2.0 parts by mass of ethyl lactate

The procedure of Example 1 was repeated except that the solution used was changed, to obtain a copolymer (2) and a resist composition (2).
The polymerization initiator (c) supplied during the initial 5% polymerization reaction period was 68% by mass of the total supply amount of the polymerization initiator (c).
The Mw, Mw / Mn, N (v1) to N (v5), and Nave of the obtained copolymer (2) are shown in Table 3. Further, the solubility of the obtained copolymer (2) and the sensitivity of the obtained resist composition (2) are shown in Table 4.

Comparative Example 2
The following mixed solution was used for solution S1, solution T1, and a polymerization initiator (c) solution.
(Solution S1)
12.89 parts by mass (100 mol%) of monomer (1)
0 parts by mass (0 mol%) of the monomer (2)
0 parts by mass (0 mol%) of monomer (3)
Ethyl lactate 100.7 parts by mass (solution T1)
Monomer (1) 34.30 parts by mass (40 mol%)
29.75 parts by mass (40 mol%) of monomer (2)
Monomer (3) 20.65 parts by mass (20 mol%)
1.97 parts by mass of dimethyl-2,2'-azobisisobutyrate (1.73 mol% relative to the total supply of monomers in solution S1 and solution T1)
Ethyl lactate 116.5 parts by mass (polymerization initiator (c) solution)
0.666 parts by mass of dimethyl-2,2'-azobisisobutyrate (0.58 mol% relative to the total supply of monomers in solution S1 and solution T1)
10.4 parts by mass of ethyl lactate

The procedure of Example 1 was repeated except that the solution used was changed, to obtain a copolymer (3) and a resist composition (3).
The polymerization initiator (c) supplied during the initial 5% polymerization reaction period was 32% by mass of the total supply amount of the polymerization initiator (c).
The Mw, Mw / Mn, N (v1) to N (v5), and Nave of the obtained copolymer (3) are shown in Table 3. Further, the solubility of the obtained copolymer (3) and the sensitivity of the obtained resist composition (3) are shown in Table 4.

As can be seen from Tables 3 and 4, the copolymer for lithography (1) obtained in Example 1 is excellent in the solubility of heptane which is a low polar solvent and methanol which is a high polar solvent, The resist composition (1) using the combination (1) was excellent in sensitivity.
On the other hand, the copolymer (2) obtained in Comparative Example 1 in which the value of N (v1) / Nave is small is inferior to the solubility of heptane which is a low polar solvent, and the resist composition using the copolymer (2) Object (2) was inferior in sensitivity. Further, the copolymer (3) obtained in Comparative Example 2 having a large amount of the polymerization initiator (c) supplied in the initial 5% polymerization reaction period was inferior in the solubility of methanol, which is a highly polar solvent.

The substrate on which the pattern obtained by the method for producing a substrate on which the pattern according to the present invention is formed has a defect, and has a fine pattern with high accuracy. A substrate having such a fine pattern with few defects and having high accuracy can be suitably used for a semiconductor manufacturing process such as IC; integrated circuit such as personal computer and tablet; liquid crystal display etc.

Claims (8)

A monomer (a) containing an acid leaving group, a monomer (b) not containing an acid leaving group, and a polymerization initiator (
c) is fed into the reactor to form a polymer, and the molecular weight distribution (Mw / Mn) is 1.1 to 1
. 7. A method for producing a copolymer for lithography, which is 7.
The monomer (a) containing the acid leaving group has an ethylenic double bond, and the monomer (b) not containing the acid leaving group contains a polar group, and the polymerization initiator ( c) has a 10 hour half-life temperature of 50
A thermal polymerization initiator which is at a temperature of
The initial 5% of the polymerization reaction period of the polymerization reaction period from Polymerization initiation to completion of polymerization, the polymerization initiator (
The copolymer obtained by feeding 5 to 30% by mass of the total feed of c) into the reactor is obtained
A method for producing a copolymer for lithography, which satisfies the following conditions.
(Conditions) In the elution curve obtained by gel permeation chromatography (GPC), the eluate showing the peak related to the copolymer for lithography was divided into five fractions in the order of elution so as to equalize the volume. Among the all monomer units constituting the copolymer contained in the first fraction eluted first, a monomer unit containing an acid-eliminating group (
A monomer unit (A) containing an acid-eliminating group among all monomer units constituting the copolymer contained in the total of the five fractions, wherein the ratio of A) is N (v1) mol% N (v1) / Nave is 1.01 to 1.20, assuming that the ratio of Nave) is Nave mol%. The method for producing a copolymer for lithography according to claim 1, wherein the N (v1) / Nave is 1.01 to 1.09. The monomer (a) containing the acid leaving group, and the monomer (b) not containing the acid leaving group are
The copolymer for lithography according to claim 1 or 2, which is (meth) acrylic acid ester
Manufacturing method. The monomer (a) containing an acid-eliminable group is a (meth) acrylic acid ester having a C6-C20 alicyclic hydrocarbon group and an acid-eliminable group. The manufacturing method of the copolymer for lithography as described in any one of these. The preparation of the copolymer for lithography according to any one of claims 1 to 4, wherein the monomer (b) not containing an acid leaving group contains a monomer (b1) containing a lactone skeleton. Method. The lithography copolymer according to any one of claims 1 to 5, wherein the monomer (b) not containing an acid leaving group contains a monomer (b2) containing a hydrophilic group. Production method. A resist comprising the step of mixing the copolymer obtained by the method for producing a copolymer for lithography according to any one of claims 1 to 6 and a compound capable of generating an acid upon irradiation with an active energy ray or radiation. Method of making the composition. A step of applying a resist composition obtained by the method for producing a resist composition according to claim 7 on a substrate to be processed, a step of exposing with light of a wavelength of 250 nm or less, and a step of developing using a developer. And a method of manufacturing a patterned substrate.

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