JP2016014116A - Method and device of producing polymer for semiconductor lithography, and container for semiconductor lithography raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polymer for semiconductor lithography that is reduced in metal impurity concentration.SOLUTION: A method of producing a polymer for semiconductor lithography has the step of using a solvent stored in a container whose inner wall surface is a surface composed of stainless steel electrolytically polished or a surface having undergone glass lining treatment.

Description

  The present invention relates to a method for producing a polymer for semiconductor lithography, a container for semiconductor lithography raw material used in the production apparatus, and a production apparatus provided with the container for semiconductor lithography raw material.

Lithography in the semiconductor manufacturing technology (semiconductor lithography) means a step of forming a resist pattern on a substrate using light, an electron beam or the like.
2. Description of the Related Art In recent years, miniaturization has further progressed due to advances in lithography technology, and accordingly, there has been a demand for higher purity of a polymer for semiconductor lithography used in the lithography process or a composition containing the polymer.

Patent Document 1 discloses that impurity foreign matter is prevented from being mixed in the process of manufacturing a semiconductor manufacturing composition solution (resist polymer solution, resist composition solution, or immersion composition solution) used in a lithography process. Therefore, it is described that electrolytic polishing and lining treatment are performed on the inner surface of the pipe when the composition solution for semiconductor production is fed.
Further, in Patent Document 2, in an immersion exposure liquid filled between an exposure apparatus and a wafer at the time of exposure, deterioration of transmittance and generation of fine particles are caused by components eluted from a storage container. In order to prevent this, it is described that the inner surface of a storage container for immersion exposure liquid is subjected to electrolytic polishing.
Patent Document 3 describes a method of preventing the polymer from adhering to the polymerization tank by performing buffing on the inner wall surface of the polymerization tank in which emulsion polymerization is performed and then performing electrolytic polishing.

JP 2010-20014 A JP 2008-192641 A JP 2003-277405 A

However, in recent years, the development of microfabrication technologies such as lithography has made semiconductor devices more sophisticated, and it has often been observed that the performance and stability of semiconductor devices are reduced due to the presence of very low levels of metal impurities. Has been.
The main factors of such metal impurities are light metals such as sodium and heavy metals such as iron contained in a polymer or composition used in the semiconductor lithography process (for example, a polymer for semiconductor lithography or a solution thereof, or a resist composition). It has been confirmed that there is.
Conventionally, the metal impurity concentration in the polymer compound used in the semiconductor lithography process is selected from materials that meet strict impurity concentration standards, and thorough process management is performed so that metal impurities are not mixed in the polymer compound manufacturing stage. It is managed to a low level by doing.
However, the conventional level is not always sufficient, and it is required to further reduce the metal impurity concentration in the material used for semiconductor lithography.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a polymer for semiconductor lithography having a reduced metal impurity concentration, a container used in the production method, and a production apparatus.

  The inventors of the present invention have conducted intensive research, paying particular attention to containers that contain raw materials used in the production of polymers used in semiconductor lithography. As a result, the elution of metal impurities from the container containing the raw material is less than the elution of metal impurities from the reaction container in contact with the heated product, but in recent high-precision semiconductor devices. Found that it can affect its performance and stability. The inventors have found that reducing the elution of metal impurities from the container contributes to lowering the level of metal impurities required in a polymer for semiconductor lithography, and have reached the present invention.

The present invention includes the following [1] to [9].
[1] A method for producing a polymer for semiconductor lithography, which uses a solvent contained in a container whose inner wall surface is either an electropolished stainless steel surface or a glass-lined surface. The manufacturing method of the polymer for semiconductor lithography which has a process.
[2] A method for producing a polymer for semiconductor lithography, wherein the inner wall surface is one of a surface made of electropolished stainless steel, a surface treated with glass lining, or a surface coated with a fluorine-containing coating agent. The manufacturing method of the polymer for semiconductor lithography which has the process of using raw materials other than a solvent accommodated in the container which is.
[3] For semiconductor lithography according to [1] or [2], wherein the inner wall surface is a surface made of electropolished stainless steel, and the arithmetic average roughness Ra of the inner wall surface is 0.5 μm or less. A method for producing a polymer.

[4] A container for containing a raw material used for manufacturing a polymer for semiconductor lithography, wherein the raw material is a solvent, and an inner wall surface is a surface made of electrolytically-polished stainless steel or glass-lined. A container for semiconductor lithography raw material, which is one of the surfaces.
[5] A container for containing a raw material used for the production of a polymer for semiconductor lithography, wherein the raw material is a raw material other than a solvent, and an inner wall surface is made of electrolytically-polished stainless steel, glass lining A container for a raw material of semiconductor lithography, which is either a treated surface or a surface coated with a fluorine-containing coating agent.
[6] The semiconductor lithography raw material according to [4] or [5], wherein the inner wall surface is a surface made of electropolished stainless steel, and the arithmetic average roughness Ra of the inner wall surface is 0.5 μm or less. Container.

[7] An apparatus for producing a polymer for semiconductor lithography, the apparatus for producing a polymer for semiconductor lithography comprising the container for a raw material for semiconductor lithography according to any one of [4] to [6].
[8] Further, a container for storing a liquid other than the raw material, the inner wall surface of which is made of stainless steel, is subjected to electrolytic polishing treatment, is subjected to glass lining treatment, or is coated with a fluorine-containing coating agent. The manufacturing apparatus according to [7], comprising any one of the containers.
[9] Furthermore, the inner wall surface is provided with a pipe that is either a surface made of stainless steel and subjected to an electropolishing treatment, a surface subjected to a glass lining treatment, or a surface coated with a fluorine-containing coating agent, [7] or [8] The production apparatus according to [8].

According to the method for producing a polymer for semiconductor lithography of the present invention, a polymer for semiconductor lithography with reduced metal impurities can be obtained.
By producing a polymer for semiconductor lithography using the raw material accommodated in the container for semiconductor lithography raw material of the present invention, it is possible to realize a low level of metal impurities in the polymer for semiconductor lithography.
By producing a polymer for semiconductor lithography using the production apparatus of the present invention, a low level of metal impurities in the polymer for semiconductor lithography can be realized.

It is a schematic block diagram which shows an example of the manufacturing apparatus of the polymer for semiconductor lithography concerning this invention.

The polymer in the present invention means a dry powdery polymer or polymer solution obtained by polymerizing monomers. The polymer may contain a compound inevitable in the production process. The dry powder means a powder having a liquid content of 5% by mass or less.
The liquid content is determined by measuring the content of each of the residual monomer, residual moisture, and residual solvent contained in the polymer powder to be measured, and calculating the ratio of the total to the polymer powder. Is the value obtained.
The above components (residual monomer, residual moisture, residual solvent) are each at least one of liquid chromatography, gas chromatography and Karl Fischer moisture meter, if necessary, in combination of two or more methods, The content of the components can be measured, and the proportion of the total of them in the polymer powder can be calculated.

The “polymer solution” is a solution composed of a polymer and a solvent, or a solution composed of a polymer, a solvent, and a compound inevitable in the production process. The content of the polymer in the polymer solution can be appropriately set in consideration of the type and use of the polymer, but from the viewpoint of production, 5 to 70% by mass is preferable, and 8 to 60% by mass is more preferable. 10 to 50% by mass is particularly preferable.
The “polymer solution” includes, for example, a polymerization reaction solution obtained by polymerizing a monomer, a polymer solution obtained by purifying the polymerization reaction solution and dissolving a dried polymer powder in a solvent, A concentrated solution obtained by concentrating the polymer solution, a polymer solution or a filtrate obtained by filtering the concentrated solution, and the like are included.

In the present specification, a composition containing the “polymer solution” and an additive is referred to as a composition.
The composition is, for example, a resist composition. The resist composition contains the polymer solution and further contains additives necessary for functioning as a resist composition. A well-known thing can be used for an additive. As the polymer in the resist composition, a polymer known as a resist polymer can be used.

In the present invention, the “raw material” means each compound used in the step of carrying out the polymerization reaction and each compound newly used in the step after the polymerization reaction in the step of producing the polymer for semiconductor lithography.
The “raw material” is divided into “solvent” and “raw material other than solvent”. As the “solvent”, a polymerization solvent used in a step of performing a polymerization reaction, a poor solvent used in a step of performing reprecipitation or recycle, a diluted solvent used in a step of diluting, a wet powder or a polymer in a dry powder form. Good solvents used in the process of forming a solution, solvents used to dissolve the raw materials, solvents used in the process of washing the reaction vessel or piping, resist solvents used in the process of producing the resist composition, etc. It is done. Examples of the “raw material other than the solvent” include a monomer used in the step of performing the polymerization reaction, a polymerization initiator, and an additive for the polymerization reaction (for example, a radical scavenger, an acid scavenger, etc.). The “raw material other than the solvent” is preferably a liquid.

<Polymer for lithography>
The polymer for lithography in the present invention is not particularly limited as long as it is a polymer used in the lithography process. For example, a resist polymer used for forming a resist film, an antireflection film (TARC) formed on the upper layer of the resist film, or a reflection used for forming an antireflection film (BARC) formed on the lower layer of the resist film. Examples thereof include a polymer for prevention film, a gap fill film polymer used for forming a gap fill film, and a polymer for top coat film used for forming a top coat film.
Examples of the resist polymer include a copolymer containing one or more of the structural units having the acid-eliminable group and one or more of the structural units having the polar group.

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 high absorption performance with respect to light in a wavelength region where the photosensitive component in the resist composition is sensitive. Specific examples include an anthracene ring, naphthalene ring, benzene ring, quinoline ring. , A group having a ring structure (optionally substituted) such as a quinoxaline ring and a thiazole ring. In particular, when KrF laser light is used as irradiation light, an anthracene ring or an anthracene ring having an arbitrary substituent is preferable, and when ArF laser light is used, a benzene ring or a benzene having an arbitrary substituent A ring is preferred.
Examples of the optional substituent include a phenolic hydroxyl group, an alcoholic hydroxyl group, a carboxy group, a carbonyl group, an ester group, an amino group, and an amide group. Among these, those having a protected or unprotected phenolic hydroxyl group as the light absorbing group are preferable from the viewpoint of good developability and high resolution. Examples of the structural unit / monomer having the light-absorbing group include benzyl (meth) acrylate and p-hydroxyphenyl (meth) acrylate.

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.
Examples of the polymer for the topcoat film used in immersion lithography include a copolymer containing a structural unit having a carboxyl group, a copolymer containing a structural unit having a fluorine-containing group substituted with a hydroxyl group, and the like.

<Method for producing polymer>
The method for producing a lithographic polymer of the present invention is not particularly limited as long as it is a method having a step of using a solvent contained in a semiconductor lithography raw material container described later or a raw material other than the solvent, and a known method is used. Can do.
In general, a polymerization step in which a monomer is polymerized in a polymerization vessel to obtain a polymerization reaction solution, a polymer is precipitated from the polymerization reaction solution in a reprecipitation vessel, and a precipitate (wet powder) is further removed using a filtration vessel. A recovery step to recover and a method of drying the precipitate to obtain a dry powder of the target polymer, or the precipitate (wet powder) or the dry powder as a good solvent in the redissolving container A method of obtaining a polymer solution in which a target polymer is dissolved in a solvent through a dissolving step of dissolving is preferable.

[Polymerization process]
A solution polymerization method is used as the polymerization method. That is, the polymerization reaction solution is obtained by radical polymerization of the monomer using a polymerization initiator in the presence of a polymerization solvent.
As the monomer, the liquid polymerization initiator, and the polymerization solvent, those individually contained in a container (container for semiconductor lithography raw material; hereinafter also simply referred to as raw material container) are used. The powdery polymerization initiator is used in the form of a solution in the raw material preparation container. Specifically, the powdery polymerization initiator may be directly dissolved in the monomer, may be dissolved in the monomer and the polymerization solvent, or may be dissolved only in the polymerization solvent.
In the solution polymerization method, the supply of the monomer and the polymerization initiator to the polymerization vessel may be a continuous supply or a drop supply. As a solution polymerization method, a monomer and a polymerization initiator are dropped into a polymerization vessel from the viewpoint that a variation in average molecular weight and molecular weight distribution due to differences in production lots is small and a reproducible polymer can be easily obtained. The dropping polymerization method is preferred.

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.
A monomer may be dripped only with a monomer, and may be dripped as a monomer solution which melt | dissolved the monomer in the polymerization solvent within the raw material preparation container.
A polymerization solvent and / or monomer may be charged into the polymerization vessel in advance.
The monomer and the polymerization initiator may be supplied to the raw material preparation container from the raw material container that accommodates them independently, mixed in the raw material preparation container, and then dropped into the polymerization container; They may be dropped from the raw material container into the polymerization container; they may be mixed in pipes supplied from the independent raw material containers to the polymerization container and dropped into the polymerization container.
One of the monomer and the polymerization initiator may be dropped first, and then the other may be dropped with a delay, or both may be dropped at the same timing.
The dropping rate may be constant until the end of dropping, or may be changed in multiple stages according to the consumption rate of the monomer or the polymerization initiator.
The dripping may be performed continuously or intermittently.
The polymerization temperature is preferably 50 to 150 ° C.
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. In the case of adding a radical scavenger, the radical scavenger is supplied from a raw material container independently containing the radical scavenger to the polymerization container.

Examples of the polymerization solvent include the following.
Ethers: chain ether (diethyl ether, propylene glycol monomethyl ether, etc.), cyclic ether (tetrahydrofuran (hereinafter referred to as “THF”), 1,4-dioxane, etc.) and the like.
Esters: methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, propylene glycol monomethyl ether acetate (hereinafter referred to as “PGMEA”), γ-butyrolactone, and the like.
Ketones: acetone, methyl ethyl ketone (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 initiator, those that generate radicals efficiently by heat are preferable. For example, azo compounds (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.

[Recovery process]
The polymerization reaction solution obtained in the polymerization step is mixed with a poor solvent to precipitate a polymer to obtain a precipitate. This technique is called a reprecipitation method, and is effective for removing unreacted monomers, polymerization initiators and the like remaining in the polymerization reaction solution. If the unreacted monomer remains as it is, the sensitivity decreases when used as a resist composition, so it is preferable to remove it as much as possible. The monomer content as an impurity in the polymer obtained by the production method of the present invention is more preferably 2.0% by mass or less, further preferably 1.0% by mass or less, and particularly preferably 0.29% by mass or less. 0.25% by mass or less is most preferable.
The poor solvent is a solvent that has a small ability to dissolve the target polymer and from which the polymer can precipitate. According to the composition of the polymer, known ones can be appropriately selected and used. Methanol, isopropyl alcohol, diisopropyl ether, heptane, or water is preferable because unreacted monomers, polymerization initiators, and the like used in the lithography polymer can be efficiently removed. A poor solvent may be used individually by 1 type, and may use 2 or more types together.

  In the recovery step, the poor solvent is supplied from the raw material container containing the poor solvent alone to the reprecipitation container, and the polymerization reaction solution is dropped into the poor solvent to precipitate the polymer in the polymerization reaction solution. The amount of the poor solvent when the polymerization reaction solution is dropped into the poor solvent is not particularly limited, but is preferably equal to or more than that of the diluted solution in terms of easier reduction of unreacted monomers, and is 3 on a mass basis. Is preferably 4 times or more, more preferably 4 times or more, still more preferably 5 times or more, and particularly preferably 6 times or more. The upper limit is not particularly limited, but if it is too much, the working efficiency in the subsequent filtration step is deteriorated. For example, 10 times or less is preferable on a mass basis.

Before mixing the polymerization reaction solution with the poor solvent, the polymerization reaction solution may be diluted to an appropriate solution viscosity with a diluent solvent, if necessary. Specifically, the dilution solvent is supplied from the raw material container containing the dilution solvent alone to the polymerization container after the completion of the polymerization reaction, and is mixed with the polymerization reaction solution in the polymerization container for dilution.
Examples of the dilution solvent include 1,4-dioxane, acetone, THF, MEK, MIBK, γ-butyrolactone, PGMEA, PGME, and ethyl lactate. These may use 1 type and may use 2 or more types together.

In the recovery step, the target polymer is obtained in the form of a wet powder by separating the precipitate deposited in the poor solvent using a filtration container.
Alternatively, after the filtered wet powder is dispersed again in a poor solvent in the reprecipitation container, the operation of filtering using the filtration container is repeated to obtain the target polymer precipitate. This process is referred to as “librarian” and is effective for further reducing impurities such as unreacted monomers and polymerization initiator remaining in the wet powder.
From the viewpoint that the polymer can be obtained while maintaining high productivity, it is preferable to recover the polymer precipitate only by the reprecipitation method without performing the rethrowing.

[Drying process]
By drying the deposit (wet powder) obtained in the recovery step, a dry powder of the target polymer can be obtained.
The drying method is not limited as long as the wet powder can be dried to a desired liquid content, and a known drying method can be used. From the viewpoint of drying in a shorter time, a vacuum drying method in which the pressure is reduced in a dry atmosphere, a heat drying method in which the heat is dried in a dry atmosphere, or a vacuum heat drying method in which pressure is reduced and heated in a dry atmosphere is preferable.
From the viewpoint of lithography performance, the dry powder obtained in the drying step preferably has a liquid content of 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 1% by mass or less.

[Dissolution process]
The precipitate (wet powder) obtained in the recovery step or the dry powder obtained in the drying step is dissolved in a good solvent. Thereby, a polymer solution in which the target polymer is dissolved in a good solvent is obtained.
Specifically, the good solvent is supplied to the re-dissolution container from the raw material container that contains the good solvent alone, and the wet powder or dry powder polymer is dissolved in the good solvent in the re-dissolution container. To obtain a polymer solution.
As the good solvent, a known solvent capable of dissolving the target polymer can be used, and the solvents mentioned above as the polymerization solvent can be used. When the target polymer is used for the production of a resist composition, the same solvent as the resist solvent in the resist composition is preferably used as a good solvent in the dissolution step.

[Concentration process]
The solution obtained in the dissolution step may be concentrated using a concentration container to obtain a concentrated solution in which the target polymer is dissolved in a good solvent. By performing the concentration, the remaining low-boiling compounds can be removed.
A known concentration method can be used. It is preferable to concentrate under reduced pressure because it can be concentrated in a short time. The degree of reduced pressure in the case of concentration under reduced pressure is preferably 50 kPa or less, more preferably 40 kPa or less, and further preferably 30 kPa or less. The lower limit value of the degree of decompression is not particularly limited, but is actually 0.05 kPa or more.
In addition, heating during vacuum concentration is also preferable because it can be concentrated in a short time. As heating temperature, 20 degreeC or more is preferable, 30 degreeC or more is more preferable, and 40 degreeC or more is further more preferable. In addition, the heating temperature is preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and further preferably 80 ° C. or lower in terms of preventing thermal degradation of the polymer.
During the concentration, it is preferable to carry out stirring while preventing bumping. Moreover, it is preferable to concentrate in a pressure-resistant metal container as a concentrating container from the viewpoint that pressure control can be performed and heat temperature is excellent and reaction temperature control becomes easy. As the metal, stainless steel (hereinafter also referred to as SUS) is preferable because it has high corrosion resistance and can reduce the mixing of metal impurities into the polymer.

[Filtering process]
The solution obtained in the dissolution step or the concentrate obtained in the concentration step may be filtered as necessary. Filtration can be performed using a known filtration container. As a result, a polymer solution with reduced polymer gel and foreign matter can be obtained.
In view of the fact that the pressure loss before and after the filtration filter can be kept low and the filtration can be performed in a short time, it is preferable to filter the solution obtained in the dissolution step before the concentration step.
In terms of efficiently reducing polymer gels and foreign substances that may be mixed into the final product, it is preferable to filter the obtained concentrated solution after the concentration step.
Both the solution obtained in the dissolving step and the concentrated solution may be filtered. That is, after filtering the solution obtained in the dissolution step, the obtained filtrate may be subjected to the concentration step and concentrated, and the resulting concentrated solution may be further filtered.

<Semiconductor lithography raw material container (raw material container)>
In the present invention, as a raw material container for containing a solvent alone, a container whose inner wall surface is either a surface made of stainless steel subjected to electropolishing treatment or a surface subjected to glass lining treatment (hereinafter referred to as container (X) Is used).
In the step of producing the target polymer for semiconductor lithography, when a plurality of types of solvents are used, the solvent contained in the container (X) is used as a part or all of them. It is preferable that all of the plural types of solvents are solvents contained in the container (X).

In the present invention, as a raw material container that independently contains raw materials other than the solvent, the inner wall surface is a surface made of stainless steel that has been subjected to an electropolishing treatment, a surface that has been glass-lined, or a surface that has been coated with a fluorine-containing coating agent Or a container (hereinafter referred to as container (Y)).
The raw materials contained in the container (Y) are used as part or all of the plural types of raw materials (excluding the solvent) used in the step of producing the target polymer for semiconductor lithography. It is preferable that all of the plural types of raw materials are the raw materials accommodated in the container (Y). In the case where a plurality of types of raw materials stored in the container (Y) are used, the material or processing method of each container (Y) may be the same or different.

It is preferable to use the raw materials contained in either the container (X) or the container (Y) as at least all of the raw materials used in the polymerization step.
For example, when the raw materials used in the polymerization step are a polymerization solvent, a monomer, and a liquid polymerization initiator, a polymerization solvent accommodated in the container (X) and a single amount accommodated in the container (Y) The polymerization initiator contained in the container and the container (Y) is preferably supplied directly to the polymerization reaction container or supplied to the polymerization reaction container via the raw material preparation container.

As the container (X) or the container (Y), the container whose inner wall surface is made of stainless steel subjected to electrolytic polishing is obtained by electrolytic polishing of at least the inner wall of a container made of stainless steel. It is preferable that the entire inner wall surface be subjected to electrolytic polishing treatment.
Stainless steel is not particularly limited, and a known steel type can be used. For example, SUS304 (Fe: about 70 mass%, Cr: 18-20 mass%, Ni: 8-10 mass%), SUS316 (Fe: about 70 mass%, Cr: 16-18 mass%, Ni: 10-14 mass) %, Mo: 2-3 mass%), SUS316L (Fe: about 70 mass%, Cr: 16-18 mass%, Ni: 10-14 mass%, Mo: 2-3 mass%) and the like.
The electrolytic polishing treatment can be performed by a known method. When electrolytic polishing is performed on stainless steel, metal ions are eluted from the surface of the stainless steel and the surface is smoothed.

The condition of the electrolytic polishing treatment is that the surface of the stainless steel that has been subjected to the electrolytic polishing treatment has an arithmetic average roughness Ra indicating surface smoothness of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.2 μm or less. It is preferable to set so that
The arithmetic average roughness value (Ra, unit: μm) in the present invention is a value measured in accordance with JIS B0601-2001.
By sufficiently smoothing the inner wall surface of the container so that the arithmetic average roughness Ra is 0.5 μm or less, metal elution from the inner wall surface can be sufficiently reduced. Specifically, when an elution test is performed by the following method, the elution amount of iron, the elution amount of chromium, and the elution amount of nickel can be suppressed to 0.5 ppb or less, preferably 0.1 ppb, respectively. The smaller the value of the arithmetic average roughness Ra, the more the metal elution can be reduced.
The lower limit value of the arithmetic average roughness Ra is not particularly limited. It is substantially 0.05 μm or more.

(Dissolution test)
A cylindrical test piece (length: 30 mm, diameter: 12 mm) having the same material and the same surface smoothness as the test object is used. After this test piece is stirred and washed with methanol, 70 mL of ethyl lactate and the test piece after washing are put into a polyethylene clean bottle, the liquid temperature is kept at 25 ° C., and the mixture is allowed to stand for 24 hours for storage. Before and after standing for 24 hours, the contents of metals (iron, chromium, nickel) in ethyl lactate were measured by the following methods, respectively, and the difference in values before and after standing was determined as the elution amount of each metal (unit: ppb ).

(Measurement method of iron, chromium and nickel content in dissolution test)
The metal is analyzed by a high frequency inductively coupled plasma mass spectrometer (ICP-MS-Inductively Coupled Mass Mass Spectrometer: 7500 cs manufactured by Agilent Technologies), and the elution amount of each metal is determined.

A container whose inner wall surface is a glass-lined surface as the container (X) or the container (Y) is obtained by forming a glass coating (lining) on the inner wall surface of a metal or non-metal container.
The material of the container is not particularly limited. Examples thereof include stainless steel and ceramics. Stainless steel is preferred.
Formation of the glass coating (glass lining treatment) can be performed by a known method.
The thickness of the glass coating is preferably 0.5 mm or more, more preferably 1.0 mm or more. The upper limit of the film thickness is preferably 3.0 mm or less, and more preferably 2.0 mm or less.
By subjecting the entire inner wall surface of the container to a glass lining treatment, the amount of metal elution from the inner wall surface can be made zero.

As a container (Y), a container whose inner wall surface is coated with a fluorine-containing coating agent is a film (coating film) containing a fluorine-containing compound with a fluorine-containing coating agent on the inner wall surface of a metal or non-metal container. ) Is obtained.
The material of the container is not particularly limited. Examples thereof include stainless steel and ceramics. Stainless steel is preferred.
The coating treatment of the fluorine-containing coating agent can be performed by a known method.
A well-known thing can be used for a fluorine-containing coating agent. Specific examples include polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).
The thickness of the coating film is preferably less than 1 mm, more preferably 0.5 mm or less. The lower limit of the film thickness is preferably 0.1 mm or more, and more preferably 0.2 mm or more.
By performing the coating process on the entire inner wall surface of the container, the amount of metal elution from the inner wall surface can be made zero.

<Manufacturing equipment>
The apparatus for producing a polymer for semiconductor lithography of the present invention includes the container for semiconductor lithography raw material of the present invention as a container for containing the raw material alone.
That is, one or both of the container (X) that contains a solvent alone and the container (Y) that contains a raw material other than the solvent alone are provided.
When the apparatus for producing the target polymer for semiconductor lithography is provided with a plurality of raw material containers each containing a plurality of types of solvents, the container (X) is used as a part or all of them. It is preferable that all of the plurality of raw material containers is the container (X).
When the apparatus for producing the target polymer for semiconductor lithography is provided with a plurality of raw material containers each containing a plurality of types of raw materials (excluding a solvent), the container (Y) is used as a part or all of them. It is preferable that all of the plurality of raw material containers is the container (Y).

In the apparatus for producing a polymer for semiconductor lithography of the present invention, a known apparatus configuration can be used as the configuration other than the container (raw material container) for containing the raw material alone.
The apparatus configuration includes a container for storing a liquid other than the raw material. For example, a raw material preparation container, a polymerization container, a reprecipitation container, a remelting container, a filtration container, a concentration container, and the like.
At least some, preferably all, of these containers have an inner wall surface that is either a stainless steel surface that has been electropolished, a glass-lined surface, or a surface that has been coated with a fluorine-containing coating agent. It is preferable to provide a container. The inner wall surfaces of these containers are the same as those of the container (Y), including preferred embodiments.

Moreover, the said apparatus structure is equipped with piping which connects each container.
At least a part, preferably all, of these pipes, the inner wall surface is one of a surface made of stainless steel and subjected to an electropolishing treatment, a surface subjected to a glass lining treatment, or a surface coated with a fluorine-containing coating agent. It is preferable to provide piping. The inner wall surfaces of these pipes are the same as the container (Y), including the preferred embodiment.

In the apparatus for producing a polymer for semiconductor lithography of the present invention, the contents of iron, chromium, and nickel in the final product (polymer for semiconductor lithography) produced by the production apparatus are each 0.5 ppb or less. Thus, it is preferable that the container (X) or the container (Y) is used so that it is more preferably 0.1 ppb or less.
When the contents of iron, chromium, and nickel in the product are each in the above ranges, a polymer for semiconductor lithography in which metal impurities are sufficiently reduced can be obtained.

In this specification, each content of iron, chromium, and nickel in a product (polymer for semiconductor lithography) is a value obtained by measurement by the following method.
(Measurement method of iron, chromium, nickel content in products)
Metal analysis is performed using a high-frequency inductively coupled plasma mass spectrometer (ICP-MS-Inductively Coupled Plasma Mass Spectrometer: 7500 cs manufactured by Agilent Technologies) to determine the content of each metal.

<Method for producing composition for semiconductor lithography>
By producing a polymer for lithography by the above method and mixing the obtained polymer (dry powder or polymer solution) with a good solvent according to the application and an additive according to the application in a mixing container. A composition for semiconductor lithography is obtained. The good solvent is supplied to the mixing container from the raw material container that contains the good solvent alone.
As the good solvent, a good solvent contained in the container (X) is preferably used.
The mixing container has an inner wall surface similar to the inner wall surface of the container (Y), made of stainless steel, electropolished, glass-lined, or coated with a fluorine-containing coating agent. Either is preferable.

[Resist composition]
When the lithography polymer is a resist copolymer, a compound that generates an acid upon irradiation with actinic rays or radiation (photoacid generator), a resist solvent (good solvent), and an additive that is blended as necessary The chemical amplification resist composition can be prepared by mixing the agent in a mixing container. The resist solvent, the photoacid generator, and the additive are supplied to the mixing container from the raw material container that contains them individually.
As the resist solvent, the solvents listed above as the polymerization solvent can be used.
The photoacid generator can be arbitrarily selected from those that can be used as the photoacid generator of the chemically amplified resist composition. A photo-acid generator may be used individually by 1 type, and may use 2 or more types together. Examples of the photoacid generator include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinone diazide compounds, diazomethane compounds, and the like. 0.1-20 mass parts is preferable with respect to 100 mass parts of polymers, and, as for the usage-amount of a photo-acid generator, 0.5-10 mass parts is more preferable.
The chemically amplified resist composition may contain a nitrogen-containing compound, and may further contain an acid compound such as an organic carboxylic acid, an oxo acid of phosphorus, or a derivative thereof. If necessary, it may contain various additives such as surfactants, other quenchers, sensitizers, antihalation agents, storage stabilizers and antifoaming agents. As these additives, those known in the resist composition can be appropriately used.

  Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

(Test Example 1)
As a raw material container containing PGMEA (polymerization solvent) alone, a raw material container made of stainless steel (SUS304) with a capacity of 1000 L is prepared, and the arithmetic average roughness Ra of the inner wall surface is 0.5 μm or less. An electrolytic polishing treatment was performed.
(Comparative Test Example 1)
The same container for raw materials as in Test Example 1 was prepared. The electrolytic polishing treatment was not performed, and the arithmetic average roughness Ra of the inner wall surface was 0.6 μm.

(Dissolution test)
Two cylindrical specimens (length: 30 mm, diameter: 12 mm) made of the same stainless steel (SUS304) as the material of the raw material container are prepared, and one has an arithmetic average roughness Ra of 0.5 μm or less on the surface. The electrolytic polishing treatment was performed so that the other was not subjected to the electrolytic polishing treatment, and the arithmetic average roughness Ra of the surface was 0.6 μm. The above elution test was performed on each test piece, and the elution amount was determined for iron and chromium.
(Test results)
The elution amount of each metal in the same specimen as the material of the raw material container subjected to the electrolytic polishing treatment was iron: 2.2 ppb and chromium: 1.4 ppb.
On the other hand, the elution amount of each metal in the test piece not subjected to the electrolytic polishing treatment was iron: 10.6 ppb and chromium: 9.9 ppb.

[Example 1]
FIG. 1 is a schematic configuration diagram showing an example of an apparatus for producing a polymer for semiconductor lithography according to the present invention.
In this example, a resist polymer was produced using the production apparatus shown in FIG. 1, and a polymer solution was produced using the resist polymer. Each container (reference numerals 1 to 5 and 11 to 17 in the figure) and piping (reference numerals 21 to 31 in the figure) constituting the manufacturing apparatus are as follows.
Raw material mixing container 1: made of stainless steel. The inner wall surface is subjected to electrolytic polishing, and the arithmetic average roughness Ra of the inner wall surface is 0.11 μm.
Polymerization vessel (polymerization kettle) 2: A nitrogen inlet, a stirrer, a condenser, a temperature-adjustable jacket, and a thermometer are provided. Made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra is 0.12 μm.
Reprecipitation container 3: A stirrer, a condenser, a temperature-adjustable jacket, and a thermometer are provided. Made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra of the inner wall surface is 0.08 μm.
Filtration container 4: Filtration container used in the step of obtaining polymer wet powder. Made of stainless steel. The inner wall surface is subjected to electrolytic polishing, and the arithmetic average roughness Ra of the inner wall surface is 0.11 μm.
Remelting container 5: made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra of the inner wall surface is 0.13 μm.
Raw material container 11 containing a polymerization solvent: made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra of the inner wall surface is 0.10 μm.
Containers for raw materials 12, 13, 14 each containing three kinds of monomers: made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra of the inner wall surface is 0.12 μm.
Container 15 for raw materials containing a poor solvent: Made of stainless steel. The inner wall surface is subjected to electrolytic polishing, and the arithmetic average roughness Ra of the inner wall surface is 0.09 μm.
Raw material container 16 containing good solvent: made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra of the inner wall surface is 0.12 μm.
Raw material container 17 for containing resist solvent alone: Made of stainless steel. The inner wall surface is subjected to electrolytic polishing, and the arithmetic average roughness Ra of the inner wall surface is 0.11 μm.
Piping 21-31: Made of stainless steel. The inner wall surface is electrolytically polished, and the arithmetic average roughness Ra of the inner wall surface is 0.10 μm.

Under a nitrogen atmosphere, 72.6 parts of PGMEA (propylene glycol monomethyl ether acetate) is supplied as a polymerization solvent from the raw material container 11 to the polymerization container 2 through the pipe 21, and the internal temperature of the polymerization container 2 is raised to 80 ° C. It was.
Thereafter, the monomers m-1, m-2, and m-3 were supplied from the raw material containers 12 to 14 to the raw material preparation container 1 through the pipes 22 to 24, respectively. Further, the polymerization solvent PGMEA was supplied from the raw material container 11 to the raw material preparation container 1 through the pipe 25. Furthermore, the polymerization initiator (powder) is supplied to the raw material preparation container 1, and the monomers m-1, m-2, m-3, the polymerization solvent, and the polymerization initiator are mixed in the raw material preparation container 1. A dropping solution was obtained.
The dropping solution in the raw material preparation vessel 1 is dropped into the polymerization vessel 2 through the pipe 26 at a constant dropping rate over 4 hours, and the internal temperature of the polymerization vessel 2 is maintained at 80 ° C. for 3 hours. A polymerization reaction was performed.
Seven hours after the start of dropping of the dropping solution, the reaction was stopped by cooling the internal temperature of the polymerization vessel 2 to room temperature to obtain a polymerization reaction solution.
Monomer m-1 (Formula m-1 below): 30.6 parts.
Monomer m-2 (Formula m-2 below): 35.3 parts.
Monomer m-3 (formula m-3 below): 21.2 parts.
PGMEA: 130.7 parts.
Dimethyl-2,2'-azobisisobutyrate: 2.6 parts.

Next, a total of 2069.2 parts was supplied from the raw material containers 15 (methanol) and 16 (water) to the reprecipitation container 3 through the pipes 27 and 28 so that the volume ratio was methanol / water = 80/20. The internal temperature was adjusted to 40 ° C. while stirring the reprecipitation vessel 3. The polymerization reaction solution was dropped from the polymerization vessel 2 through the pipe 29 at a constant dropping rate over 2 hours to cause reprecipitation.
After the completion of the dropping of the polymerization reaction solution, the reprecipitation solution in the reprecipitation vessel 3 was supplied to the filtration vessel 4 via the pipe 30 and filtered to obtain a reprecipitation wet powder separated by filtration.
Return the obtained re-precipitation wet powder to the re-precipitation vessel 3, and supply 2069.2 parts of a mixed solvent of methanol / water = 85/15 (volume ratio) in the same manner, and adjust the internal temperature to 40 ° C. Stir for 2 hours.
After stirring for 2 hours, the slurry solution in the reprecipitation container 3 was supplied to the filtration container 4 through the pipe 30 and filtered to obtain a filtered slurry powder (polymer powder), which was dried.
The obtained polymer dry powder was supplied to the redissolving container 5. PGMEA was supplied from the raw material container 17 to the re-dissolution container 5 through the pipe 31 so that the solid content concentration of the polymer was 20% by mass. In the redissolving vessel 5, the polymer was dissolved in PGMEA to obtain a polymer solution having a solid content concentration of 25% by mass.
The metal content of the obtained polymer solution (solid content: 25% by mass, solvent: PGMEA) was less than 0.1 ppb iron and less than 0.1 ppb chromium.

1 Raw material mixing container 2 Polymerization container (polymerization kettle)
3 Reprecipitation container 4 Filtration container 5 Remelting container 11 Raw material container 12 to 14 containing polymerization solvent Raw material container 15 containing monomer 15 Raw material container 16 containing poor solvent Raw material container containing good solvent 17 Raw material containers 21-31 for containing resist solvent

Claims (9)

A method for producing a polymer for semiconductor lithography,
The manufacturing method of the polymer for semiconductor lithography which has the process of using the solvent accommodated in the container whose inner wall surface is either the surface which consists of stainless steel by which the electropolishing process was carried out, or the surface which carried out the glass lining process. A method for producing a polymer for semiconductor lithography,
A process using a raw material other than a solvent contained in a container whose inner wall surface is one of a surface made of electropolished stainless steel, a surface subjected to glass lining treatment, or a surface coated with a fluorine-containing coating agent. A method for producing a polymer for semiconductor lithography, comprising:   The method for producing a polymer for semiconductor lithography according to claim 1 or 2, wherein the inner wall surface is a surface made of electrolytically polished stainless steel, and the arithmetic average roughness Ra of the inner wall surface is 0.5 µm or less. . A container for containing raw materials used in the production of a polymer for semiconductor lithography,
The raw material is a solvent;
A container for a semiconductor lithography raw material, wherein the inner wall surface is either a surface made of stainless steel subjected to electrolytic polishing or a surface subjected to glass lining. A container for containing raw materials used in the production of a polymer for semiconductor lithography,
The raw material is a raw material other than the solvent;
A container for semiconductor lithography raw material, wherein the inner wall surface is one of a surface made of electropolished stainless steel, a glass-lined surface, or a surface coated with a fluorine-containing coating agent.   The container for a semiconductor lithography material according to claim 4 or 5, wherein the inner wall surface is a surface made of electropolished stainless steel, and the arithmetic average roughness Ra of the inner wall surface is 0.5 µm or less. An apparatus for producing a polymer for semiconductor lithography,
The manufacturing apparatus of the polymer for semiconductor lithography provided with the container for semiconductor lithography raw materials as described in any one of Claims 4-6.   Furthermore, the container contains a liquid other than the raw material, and the inner wall surface is made of either stainless steel, electropolished, glass-lined, or coated with a fluorine-containing coating agent. The manufacturing apparatus of Claim 7 provided with a certain container.   Furthermore, the inner wall surface is provided with a pipe made of any one of a stainless steel surface, an electropolished surface, a glass-lined surface, or a surface coated with a fluorine-containing coating agent. Manufacturing equipment.

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