JP6468339B2 - Method for producing polymer for semiconductor lithography - Google Patents

Description

  The present invention relates to a method for producing a polymer for semiconductor lithography.

In manufacturing processes of semiconductor elements, liquid crystal elements, etc., a resist film is formed on a substrate, and the resist film is exposed, developed, and patterned to form a resist pattern.
In recent years, resist patterns have been rapidly miniaturized due to advances in lithography technology.
Specifically, the irradiation light has been shortened from g-line (wavelength: 438 nm) or i-line (wavelength: 365 nm) to DUV (Deep Ultra Violet) having a wavelength of 300 nm or less. At present, the KrF excimer laser ( (Wavelength: 248 nm) Lithography technology and A
rF excimer laser (wavelength: 193 nm) lithography technology has been introduced.
Further, vigorous research has been conducted on EUV (wavelength: 13.5 nm) of shorter wavelength, electron beam lithography technology, and immersion lithography technology for performing exposure in a liquid such as water.
High sensitivity is required for a resist material used for forming a resist film by lithography using irradiation light or electron beams of the short wavelength.
In response to the above demand, a chemically amplified resist containing a photoacid generator has been proposed, and improvement and development of the chemically amplified resist are currently underway.

In the lithography process, in addition to the resist film, various films such as an antireflection film, a gap fill film, and a top coat film are used.
In order to form these films, those containing a polymer are generally used, and various characteristic groups are introduced into the polymer in order to exhibit functions according to applications.
For example, examples of the chemically amplified resist polymer include those having a polar group, an acid leaving group, and the like.
Moreover, as an example of the polymer for antireflection film, it reacts with a light absorbing group that absorbs exposure light, a curing agent, etc. (
Examples thereof include those having a reactive functional group capable of crosslinking reaction).
As a method for producing a polymer (lithographic polymer) used in these lithography processes, a method in which a monomer is dissolved in a polymerization solvent and polymerized in the presence of a polymerization initiator is generally used (for example, patent documents). 3).
The polymerization reaction liquid after polymerization is the target polymer as well as raw materials (monomer, polymerization solvent, polymerization initiator, etc.)
Is included. Therefore, after the polymerization, in order to separate and recover the polymer from the polymerization reaction solution, a reprecipitation step of adding a poor solvent to precipitate the polymer, filtering to recover the polymer by filtering the reaction solution from which the polymer has precipitated A process etc. are performed.
Moreover, rinse, washing | cleaning, drying, melt | dissolution, solvent substitution, etc. are performed as needed (for example, patent documents 1, 2).
The lithographic polymer thus obtained or a solution thereof is filled in a container for storage, transportation and the like.

JP 2005-132974 A JP 2009-029874 A JP 2011-127102 A

Monomers used for the production of the polymer are roughly classified into solution-type monomers and solid-state monomers.
When preparing the monomer, the solution-like monomer can be introduced by opening the lid of the preparation kettle or transferred to the preparation kettle through a pipe, but the solid monomer is There is no choice but to open the lid of the blender.
However, when the lid of the blender is opened, metal may be mixed due to contamination from the external environment, and this metal impurity lowers the purity of the polymer and adversely affects the lithography performance. give.
Therefore, there is a demand for means for transferring a solid monomer into a solution and transferring it to a preparation kettle through a pipe.
In general, the solution is formed by heating the monomer to the melting point or higher. However, in this method, the monomer may solidify in the pipe. Moreover, when it heats too much, an oligomer may produce | generate with heat.
The present invention has been made in view of the above circumstances, and is a heavy load capable of converting a solid monomer into a solution, transferring it, suppressing contamination of the amount of metal impurities, and suppressing oligomer formation due to thermal history. It aims at providing the manufacturing method of unification.

As a result of intensive studies, the inventors have dissolved a monomer having a melting point of 5 ° C. or higher in a polymerization solvent and / or another monomer (B), thereby suppressing caking and oligomer formation in the pipe, The inventors have found a method for stably producing a polymer for semiconductor lithography and completed the present invention.

That is, this invention has the following aspect.
[1] A method for producing a polymer for semiconductor lithography, comprising the following steps (1) and (2).
(1) A step of supplying a raw material for polymerization in which a monomer (A) having a melting point of 5 ° C. or higher is dissolved in a polymerization solvent and / or another monomer (B) to a preparation kettle through a pipe ;
(2) supplying the polymerization raw material from a preparation kettle to a polymerization kettle and polymerizing it to obtain a polymer;
[2] The method for producing a polymer for semiconductor lithography according to the aspect [1], wherein the step (2) is dropping polymerization.
[3] The method for producing a polymer for semiconductor lithography according to the aspect [1] or [2], wherein the monomer (A) has a melting point of 10 ° C. or higher.

According to the production method of the present invention, the monomer can be stably supplied to the preparation kettle without deteriorating the quality of the monomer.
Therefore, the obtained polymer has a small amount of metal impurities and high reproducibility of molecular weight.

The production method of the present invention is a method for producing a polymer, comprising a step of supplying a monomer to a preparation kettle (hereinafter referred to as a preparation step) and a step of dropping a prepared monomer solution to polymerize (hereinafter referred to as a polymerization step). There,
A solid monomer raw material is dissolved in a solvent and / or another monomer and supplied in a solution state,
It is characterized by stably producing a polymer.

[First embodiment]
The first embodiment of the present invention includes the following steps (1) and (2).
Step (1);
Supplying a raw material for polymerization in which a monomer (A) having a melting point of 5 ° C. or higher is dissolved in a polymerization solvent and / or another monomer (B) to a preparation kettle through a pipe ;
Step (2);
Supplying the polymerization raw material from a preparation kettle to a polymerization kettle and polymerizing it to obtain a polymer;
[Second Embodiment]
The second embodiment of the present invention is an embodiment in which the supply from the preparation kettle to the polymerization kettle is performed by dropping.

Here, examples of the monomer polymerization method include known polymerization methods such as a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. In particular, in the case of a polymer for lithography, a solution polymerization method is preferably used from the viewpoint of molecular weight control and reproducibility.
In the solution polymerization method, a monomer is polymerized using a polymerization initiator in the presence of a polymerization solvent to obtain a polymerization reaction solution. At this time, a chain transfer agent may be used in combination. By using a chain transfer agent, a polymer having a low molecular weight and a small molecular weight distribution can be produced.
Examples of the solution polymerization method include a batch polymerization method and a dropping polymerization method. Of these, the drop polymerization method is preferred from the viewpoints of easily obtaining a reproducible polymer with small variations in average molecular weight and molecular weight distribution due to differences in production lots.

In the dropping polymerization method, the inside of the polymerization vessel is heated to a predetermined polymerization temperature, and then the monomer and the polymerization initiator are dropped into the polymerization vessel independently or in any combination.
The polymerization vessel is not particularly limited as long as it is provided in a normal production facility used for production of a polymer.
A monomer may be dripped only with a monomer, and may be dripped as a monomer solution which dissolved the monomer in the polymerization solvent.
The polymerization solvent and / or monomer may be charged into the polymerization vessel in advance.
The polymerization initiator may be dissolved directly in the monomer, may be dissolved in the monomer solution, or may be dissolved only in the polymerization solvent.
The monomer and the polymerization initiator may be dropped in the polymerization kettle after they are mixed in advance in the preparation kettle; they may be dropped into the polymerization kettle from independent tanks; They may be mixed immediately before the addition and dropped into the polymerization kettle.
Specific examples of the case where the mixture is preliminarily mixed in the mixing kettle and then dropped into the polymerization kettle are as follows. First, raw materials (monomer, polymerization initiator, polymerization solvent, etc.) are poured into the mixing kettle having a stirrer,
A monomer solution is prepared by stirring with a stirrer.
Separately, a polymerization solvent is poured into a polymerization kettle having a stirrer, a jacket and a condenser, and kept at a constant temperature. Thereafter, the monomer solution in the preparation kettle is supplied to the polymerization kettle and dropped into a polymerization solvent maintained at a constant temperature to polymerize the monomer. Thereby, the polymerization reaction solution containing the target polymer is obtained.
When dropping into the polymerization kettle from each independent storage tank, after dropping one of the monomers and the polymerization initiator first, the other may be dropped with a delay, or both may be dropped at the same timing.

The dropping speed may be constant until the dropping is completed, or may be changed in multiple stages according to the consumption speed of the monomer or the polymerization initiator.
The dripping may be performed continuously or intermittently.
The polymerization temperature is preferably 50 to 150 ° C.
After a polymerization reaction at a predetermined polymerization temperature for a predetermined time, the polymerization reaction is stopped to obtain a polymerization reaction solution. As a method for stopping the polymerization reaction, a process of cooling the reaction solution is generally used, but it can also be stopped by adding a radical scavenger.

<Polymerization solvent>
Examples of the polymerization solvent include the following.
Ethers: chain ethers (diethyl ether, propylene glycol monomethyl ether, etc.), cyclic ethers (tetrahydrofuran (hereinafter referred to as “THF”), 1,4-dioxane, etc.) and the like.
Esters: methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, propylene glycol monomethyl ether acetate (hereinafter referred to as “PGMEA”), γ-
Butyrolactone and the like.
Ketones: acetone, methyl ethyl ketone (hereinafter referred to as “MEK”), methyl isobutyl ketone (hereinafter referred to as “MIBK”), cyclohexanone, and the like.
Amides: N, N-dimethylacetamide, N, N-dimethylformamide and the like.
Sulfoxides: dimethyl sulfoxide and the like.
Aromatic hydrocarbons: benzene, toluene, xylene and the like.
Aliphatic hydrocarbon: hexane and the like.
Alicyclic hydrocarbons: cyclohexane and the like.
A polymerization solvent may be used individually by 1 type, and may use 2 or more types together.
As the polymerization solvent, a solvent capable of dissolving any of the monomer, the polymerization initiator, the resulting polymer, and the chain transfer agent when used in combination is preferable.

<Polymerization initiator>
As the polymerization initiator, those that generate radicals efficiently by heat are preferable.
For example, an azo compound (2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] Etc.), organic peroxides (2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane, di (4-tert-butylcyclohexyl) peroxydicarbonate, etc.) and the like.
Examples of the chain transfer agent include 1-butanethiol, 2-butanethiol, 1-octanethiol, 1-decanethiol, 1-tetradecanethiol, cyclohexanethiol, 2-methyl-1-propanethiol, 2-mercaptoethanol, Mercaptoacetic acid, 1
-Thioglycerol and the like.

<Polymer>
Since the production method of the present invention dissolves the solid monomer in the production process in the polymerization solvent and / or other monomer, it can be applied to various polymer production processes. Therefore, the polymer synthesized in the production method of the present invention and filled in the container is not particularly limited, and any known polymer may be used.
Specifically, as the polymer, by structure, acrylic polymer, styrene polymer (polystyrene, etc.), vinyl chloride polymer, polyester polymer, cycloolefin polymer,
Examples thereof include vinyl ether polymers, fluorine polymers, etc., and according to use, lithography polymers, paint polymers, toner polymers, molding polymers, and the like.
Among these, a polymer for lithography is preferable in that reduction of the amount of metal impurities is strictly required.
As a polymer for lithography, if it is a polymer used in the lithography process,
There is no particular limitation. For example, resist polymer used for resist film formation, antireflection film polymer used for antireflection film formation, gap fill film polymer used for gap fill film formation, topcoat film formation The polymer for topcoat films | membranes used is mentioned.
The antireflection film may be an antireflection film (TARC) formed on the upper layer of the resist film or an antireflection film (BARC) formed on the lower layer of the resist film.

<Monomer (A)>
The monomer (A) is a monomer having a melting point of 5 ° C. or higher and crystallizing at room temperature (15 to 25 ° C.).
For example, methacrylic acid having a melting point of 15 ° C., α-methacryloxy-γ-butyrolactone (GBLMA) having a melting point of 22 ° C., 2-methacryloyloxy-2-isopropyladamantane (IPAdMA) having a melting point of 38 ° C., 3 having a melting point of 88 ° C. -Methacryloyloxy-1-hydroxyadamantane (HAdMA), and the like.

<Monomer (B)>
The monomer (B) has a melting point of less than 5 ° C. and is in a solution state at room temperature (15 to 25 ° C.)
It is a monomer that can dissolve the monomer (A).
For example, ethyl methacrylate (EMA) having a melting point of −61 ° C., tertiary butyl methacrylate (TBMA) having a melting point of −60 ° C., methyl methacrylate (MMA) having a melting point of −48 ° C.
), Normal butyl methacrylate having a melting point of −25 ° C., and the like.

Examples of the resist polymer include those containing a structural unit having a polar group.
The “polar group” is a group having a polar functional group or a polar atomic group. Specific examples include a hydroxy group, a cyano group, an alkoxy group, a carboxy group, an amino group, a carbonyl group, and a fluorine atom. A group containing a sulfur atom, a group containing a lactone skeleton, a group containing an acetal structure, a group containing an ether bond, and the like.
Among these, the resist polymer applied to the pattern forming method that is exposed to light having a wavelength of 250 nm or less preferably has a structural unit having a lactone skeleton as the structural unit having a polar group, and further has a hydrophilic group. It is preferable to have a structural unit having

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

A polymer containing a structural unit having a lactone skeleton can be obtained by polymerizing a monomer having a lactone skeleton.
The monomer having a lactone skeleton may be a compound having a lactone skeleton and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.
The monomer having a lactone skeleton has a (meth) acrylic acid ester having a substituted or unsubstituted δ-valerolactone ring and a substituted or unsubstituted γ-butyrolactone ring from the viewpoint of excellent adhesion to a substrate or the like ( At least one selected from the group consisting of (meth) acrylic acid esters is preferable, and (meth) acrylic acid esters having an unsubstituted γ-butyrolactone ring are particularly preferable.
In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acryloyloxy” means acryloyloxy or methacryloyloxy.
Specific examples of the monomer having a lactone skeleton include β- (meth) acryloyloxy-
β-methyl-δ-valerolactone, 4,4-dimethyl-2-methylene-γ-butyrolactone, β- (meth) acryloyloxy-γ-butyrolactone, β- (meth) acryloyloxy-β-methyl-γ-butyrolactone , Α- (meth) acryloyloxy-γ-butyrolactone, 2- (1- (meth) acryloyloxy) ethyl-4-butanolide, (meth) acrylic acid pantoyllactone, 5- (meth) acryloyloxy-2,6 -Norbornanecarbolactone, 8-methacryloxy-4-oxatricyclo [5.2.1.02,
6] decan-3-one, 9-methacryloxy-4-oxatricyclo [5.2.1.0
2,6] decan-3-one and the like. Examples of the monomer having a similar structure include methacryloyloxysuccinic anhydride.
Monomers having a lactone skeleton may be used singly or in combination of two or more.

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

A polymer containing a structural unit having a hydrophilic group can be obtained by polymerizing a monomer having a hydrophilic group.
The monomer having a hydrophilic group may be a compound having a hydrophilic group and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.
Examples of the monomer having a hydrophilic group include (meth) acrylic acid ester having a terminal hydroxy group; a derivative having a substituent such as an alkyl group, a hydroxy group, or a carboxy group on the hydrophilic group of the monomer; Monomers having a hydrocarbon group (for example, cyclohexyl (meth) acrylate, 1-isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentyl (meth) acrylate) , 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, etc.) having a hydrophilic group such as a hydroxy group or a carboxy group as a substituent. .
Specific examples of the monomer having a hydrophilic group include (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy-n-propyl (meth) acrylate. , 4-hydroxybutyl (meth) acrylate, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (
And (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate, and the like. From the viewpoint of adhesion to a substrate or the like, 3-hydroxyadamantyl (meth) acrylate, 3,5-dihydroxyadamantyl (meth) acrylate, 2- or 3-cyano-
5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth)
Acrylate and the like are preferable.
The monomer which has a hydrophilic group may be used individually by 1 type, and may be used in combination of 2 or more type.

The resist polymer is a chemically amplified resist polymer, and is used for a positive resist composition in which a positive resist pattern is formed by dissolving and removing an exposed portion when developed with an alkali developer. In this case, the resist polymer preferably has a structural unit having an acid leaving group in addition to the structural unit having a polar group.
The “acid leaving group” is a group having a bond that is cleaved by an acid, and a part or all of the acid leaving group is removed from the main chain of the polymer by cleavage of the bond. In a chemically amplified resist, a polymer containing a structural unit having an acid-leaving group reacts with an acid generated by exposure from a photoacid generator component to increase the polarity. Therefore, when the resist film containing the polymer is selectively exposed, the resist film becomes soluble in an alkaline developer in the exposed portion of the resist film, and a resist pattern can be formed.
The proportion of the structural unit having an acid leaving group is preferably 20 mol% or more, more preferably 25 mol% or more, out of all the structural units (100 mol%) constituting the polymer from the viewpoint of sensitivity and resolution. . Moreover, 60 mol% or less is preferable from the point of the adhesiveness to a board | substrate etc., 55 mol% or less is more preferable, and 50 mol% or less is further more preferable.

A polymer containing a structural unit having an acid leaving group is obtained by polymerizing a monomer having an acid leaving group or after polymerizing a monomer having a hydrophilic group. It is obtained by protecting with a sex group.
The monomer having an acid leaving group may be any compound having an acid leaving group and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.
Specific examples of the monomer having an acid leaving group include (meth) acrylic acid esters having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and an acid leaving group. The alicyclic hydrocarbon group may be directly bonded to an oxygen atom constituting an ester bond of (meth) acrylic acid ester, or may be bonded via a linking group such as an alkylene group.
The (meth) acrylic acid ester has an alicyclic hydrocarbon group having 6 to 20 carbon atoms, and a tertiary carbon atom at the bonding site with the oxygen atom constituting the ester bond of the (meth) acrylic acid ester. A (meth) acrylic acid ester having an alicyclic group or an alicyclic hydrocarbon group having 6 to 20 carbon atoms and a -COOR group (R may have a substituent) on the alicyclic hydrocarbon group. (Meth) acrylic acid ester in which a tertiary hydrocarbon group, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group is bonded directly or via a linking group is included.
In particular, in the case of producing a resist composition applied to a pattern forming method in which exposure is performed with light having a wavelength of 250 nm or less, preferred examples of the monomer having an acid leaving group include, for example, 2-
Methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, 1- (1′-adamantyl) -1-methylethyl (meth) acrylate, 1-methylcyclohexyl (meth) acrylate, 1 -Ethylcyclohexyl (meth)
Examples include acrylate, 1-methylcyclopentyl (meth) acrylate, 1-ethylcyclopentyl (meth) acrylate, isopropyl adamantyl (meth) acrylate, and 1-ethylcyclooctyl (meth) acrylate.
As the monomer having an acid leaving group, one type may be used alone, or two or more types may be used in combination.

The resist polymer may further include a known structural unit as necessary in addition to the above-described structural unit having a polar group and the structural unit having an acid leaving group.

As the resist polymer, a copolymer containing at least one type of structural unit having the polar group and at least one type of structural unit having the acid-eliminable group is preferable, and the structural unit having the lactone skeleton. More preferably, the copolymer includes at least one of the structural units having an acid-eliminable group, and at least one of the structural units having the lactone skeleton and the acid-leaving group. A copolymer containing at least one of the structural units having one and at least one of the structural units having the hydrophilic group is preferable.

Examples of the polymer for antireflection film include a structural unit having a light-absorbing group and an amino group, an amide group, a hydroxyl group, an epoxy group, etc. that can be cured by reacting with a curing agent to avoid mixing with the resist film. And a copolymer containing a structural unit having a reactive functional group.
The light-absorbing group is a group having a high absorption performance with respect to light in a wavelength region in which the photosensitive component in the resist composition is sensitive. , A group having a ring structure (optionally substituted) such as a quinoxaline ring and a thiazole ring. In particular, when KrF laser light is used as irradiation light, an anthracene ring or an anthracene ring having an arbitrary substituent is preferable, and Ar
When F laser light is used, a benzene ring or a benzene ring having an arbitrary substituent is preferable.
Examples of the optional substituent include a phenolic hydroxyl group, an alcoholic hydroxyl group, a carboxy group, a carbonyl group, an ester group, an amino group, and an amide group. Of these,
As a light absorbing group, those having a protected or unprotected phenolic hydroxyl group,
It is preferable from the viewpoint of good developability and high resolution.
A polymer containing a structural unit having a light absorbing group can be obtained by polymerizing a monomer having a light absorbing group. The monomer having a light-absorbing group may be a compound having a light-absorbing group and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.
Examples of the monomer having a light absorbing group include benzyl (meth) acrylate, p
-Hydroxyphenyl (meth) acrylate etc. are mentioned.

A polymer containing a structural unit having a reactive functional group can be obtained by polymerizing a monomer having a reactive functional group. The monomer having a reactive functional group may be a compound having a reactive functional group and a polymerizable multiple bond, and known ones can be used. The polymerizable multiple bond is a multiple bond that is cleaved during the polymerization reaction to form a copolymer chain, and an ethylenic double bond is preferable.
As a monomer which has a reactive functional group, what substituted the hydrophilic group of the monomer which has the hydrophilic group mentioned above with the reactive functional group etc. are mentioned, for example.
The polymer for an antireflection film may further have a known constituent unit as necessary in addition to the constituent unit having a light-absorbing group and the constituent unit having a reactive functional group. For example,
Among the structural units having a polar group described above, a structural unit having a polar group that does not correspond to a reactive functional group may be included.

Examples of polymers for gap fill films are reactive functionalities that have a suitable viscosity for flowing into narrow gaps and can be cured by reacting with curing agents to avoid mixing with resist films and antireflection films. Examples thereof include a copolymer containing a structural unit having a group, specifically, a copolymer of hydroxystyrene and a monomer such as styrene, alkyl (meth) acrylate, or hydroxyalkyl (meth) acrylate.
The topcoat film is mainly formed on the resist film by immersion lithography. Examples of the polymer for the top coat film include a copolymer containing a structural unit having a carboxyl group,
And a copolymer containing a structural unit having a fluorine-containing group substituted with a hydroxyl group.

Hereinafter, the present invention will be described by way of examples. However, these examples are not intended to limit or reduce the scope of the invention in any way, but teach conditions, parameters or values that must be used exclusively to practice the invention. It should not be interpreted as a thing. Also, unless otherwise specified, all parts and percentages are values based on weight.
The oligomer component of the monomer is GPC (Gel Permeation Chroma).
(Togography: Tosoh HLC8320GPC) was calculated in terms of polystyrene (measurement conditions: dry powder 20 mg / eluent 5 mL, eluent: THF). “Room temperature” was 25 ° C.
The monomer composition of the polymer is 1H-NMR (manufactured by JEOL, resonance frequency: 270 MHz).
Was calculated from the integrated intensity ratio of the signals derived from each constituent unit.

[Example 1]
Copolymer A was synthesized by the following synthesis procedure.
In a polymerization kettle equipped with a nitrogen inlet, a stirrer, a condenser, a temperature-adjustable jacket and a thermometer, in a nitrogen atmosphere, PGME (Propylene Glycol Monom
56.5 parts of ethyl ether) were supplied. While stirring the polymerization kettle, the internal temperature of the polymerization kettle was raised to 80 ° C.
Then, 18.7 parts (24.4 mol%) of the following monomer (m-1) was added to PGME18.
7 parts of solution, monomer m-2 18.7 parts (23.5 mol%), monomer m-3
30.5 parts (52.1 mol%), 83.0 parts of PGME as a solvent, 3.7 parts of dimethyl-2,2'-azoisobutyrate as a polymerization initiator as a dropping solution Supplied to the kettle.
This was dropped inline into the polymerization kettle at a constant dropping rate over 4 hours, and the internal temperature was 80
The temperature of 0 ° C. was held for 3 hours. Seven hours after the start of dropping of the dropping solution, the reaction was stopped by cooling to room temperature.
Thereafter, the polymerization solution was filled into a container.

[Example 2]
Copolymer B was synthesized by the following synthesis procedure.
In a polymerization kettle equipped with a nitrogen inlet, a stirrer, a condenser, a temperature-adjustable jacket, and a thermometer, under a nitrogen atmosphere, PGME (Propylene Glycol Mon)
122.5 parts of ethyl ether) was supplied. While stirring the polymerization kettle, the internal temperature of the polymerization kettle was raised to 85 ° C. Thereafter, 51.0 parts (30.0 mol%) of the following monomer m-1 was dissolved in 70.1 parts (50.0 mol%) of monomer m-4, monomer m
-3 as 26.0 parts (20.0 mol%), 220.7 parts of PGME as a solvent, and 8.0 parts of dimethyl-2,2'-azoisobutyrate as a polymerization initiator as a dropping solution And supplied to the compounding pot.
This was dropped inline into the polymerization kettle at a constant dropping rate over 4 hours, and the internal temperature was 80
The temperature of 0 ° C. was held for 3 hours. Seven hours after the start of dropping of the dropping solution, the reaction was stopped by cooling to room temperature.
Thereafter, the polymerization solution was filled into a container.

[Comparative Example 1]
When the monomer (m-1) was melted at 30 ° C. with the same raw material as in Example 1 and supplied without dissolving in the solvent, it solidified in the supply pipe and could not be supplied to the preparation kettle.
The temperature under the atmosphere around the supply pipe at this time was 5 ° C.

[Comparative Example 2]
The monomer (m-1) was melted at 80 ° C. with the same raw material as in Example 1 and was supplied without dissolving in the solvent, but an oligomer component (0.40%) was formed during dissolution. .

[Comparative Example 3]
The monomer (m-1) was melted at 50 ° C. with the same raw material as in Example 2 and was supplied without dissolving in the solvent, but an oligomer component (0.37%) was formed during dissolution. .

As described above, in Examples 1 and 2 using the production method of the present invention, an oligomer component was not generated, and the polymer was not consolidated in the supply pipe, so that a desired polymer could be obtained.
On the other hand, Comparative Examples 1 to 3 in which the monomer was supplied by being dissolved by heating could not obtain a desired polymer due to solidification in the supply pipe and generation of oligomer components.

Claims (3)

Following steps (1) and (2), and the charge of the composition ratio of two or more monomers, the difference in the composition ratio of the monomer of the obtained <br/> in the polymer, ± all monomers 0.5 The manufacturing method of the polymer for semiconductor lithography which is the mol % or less.
(1) A polymerization raw material in which a monomer (A) having a melting point of 5 ° C. or higher is dissolved in a polymerization solvent and / or a monomer (B) having a melting point of less than 5 ° C. and capable of dissolving the monomer (A), Supplying the preparation kettle through piping;
(2) supplying the polymerization raw material from a preparation kettle to a polymerization kettle and polymerizing it to obtain a polymer; The manufacturing method of the polymer for semiconductor lithography of Claim 1 whose said process (2) is dripping polymerization. The manufacturing method of the polymer for semiconductor lithography of Claim 1 or 2 whose melting | fusing point of the said monomer (A) is 10 degreeC or more.