JP2010014906A - Method for producing photoresist resin solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a photoresist resin solution by which heat history for a photoresist resin can be reduced and the photoresist resin solution can be efficiently produced. <P>SOLUTION: The method for producing a photoresist resin solution includes: a step of preparing a resin solution containing a resist resin by polymerizing a polymerizable compound; a step of purifying the resin contained in the resin solution by reprecipitation to obtain a slurry; a step of obtaining wet powder by filtering the slurry and carrying out cleaning with a cleaning solvent; a step of drying the wet powder in a constant-rate drying area to obtain a dry product; and a step of redissolving the dry product to replace the cleaning solvent with a solvent for photoresist. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a resin solution for a photoresist. More specifically, the present invention relates to a method for producing a photoresist resin solution that can reduce the thermal history of the photoresist resin and that can efficiently produce a photoresist resin solution.

  In the field of microfabrication represented by the manufacture of integrated circuit elements, lithography technology capable of finer processing is required to obtain a higher degree of integration. However, in the conventional lithography process, near ultraviolet rays such as i rays are generally used as radiation, and it is said that fine processing at the subquarter micron level is extremely difficult with this near ultraviolet rays. Therefore, for example, in order to enable fine processing at a level of 0.10 μm or less, use of radiation having a shorter wavelength is being studied. Examples of such short-wavelength radiation include an emission line spectrum of a mercury lamp, far-ultraviolet rays typified by an excimer laser, X-rays, electron beams, and the like. ) Or ArF excimer laser (wavelength 193 nm) has been attracting attention.

  Used for photolithography such as a radiation-sensitive resin composition for resist formation suitable for irradiation with such radiation, and a resin composition for forming an upper layer film or a lower layer film (antireflection film, etc.) in a multilayer resist. Many resin compositions have been proposed.

  And as a manufacturing method of resin for photoresists used for such a resin composition, for example, (1) a step of polymerizing a monomer in the presence of a solvent to obtain a solution containing a target polymer And (2) a step of purifying the polymer by a precipitation operation, (3) a step of separating the polymer, and (4) a step of drying the moist powder containing the polymer, if necessary. It is known (see, for example, Patent Documents 1 and 2).

JP 2005-320451 A Japanese Patent No. 3818454

In the conventional method for producing a resin for resist, impurities such as a solvent used in the purification step are taken into the pores and the like in the polymer and are difficult to remove, and are removed by a drying step such as vacuum drying. Needs to be dried by giving a heat history as high as possible for a long time. Further, when the drying process is not performed, it is necessary to use a large amount of solvent at the time of solvent replacement, and it is necessary to give a long heat history when removing the solvent by heating and concentration.
However, the resist resin is easily decomposed by a heating operation, and if a high temperature and long-time heat history are given, there is a problem that a part of the structural unit is decomposed and deteriorates. It was.
Therefore, the present situation is that there is a demand for a method for producing a photoresist resin solution that has a low thermal history applied to the resin and can efficiently obtain a high-quality resin solution.

  It is an object of the present invention to provide a method for producing a photoresist resin solution that can reduce the thermal history of the photoresist resin compared to the prior art and that can efficiently produce a photoresist resin solution.

The present invention is as follows.
[1] A method for producing a resin solution for a photoresist,
(1) a resin solution preparation step of preparing a resin solution containing a photoresist resin by polymerizing a polymerizable compound;
(2) a reprecipitation step of refining the resin contained in the resin solution to obtain a slurry;
(3) a washing step of filtering the slurry and obtaining a wet powder by washing with a washing solvent;
(4) a drying step of drying the wet powder to obtain a dried product;
(5) a solvent replacement step of re-dissolving the dried product and replacing the cleaning solvent with a photoresist solvent,
In the drying step, the wet powder is dried in a constant rate drying region.
[2] The method for producing a resin solution for a photoresist according to the above [1], wherein the liquid content of the dried product obtained by the drying step is 10% or less.
[3] The method for producing a photoresist resin solution according to [1] or [2], wherein a drying temperature in the drying step is 70 ° C. or lower.

  According to the method for producing a resin solution for photoresists of the present invention, the drying of the wet powder in the drying process is performed only in the constant rate drying region, so the time required for the drying process can be shortened, and the target resin can be reduced. Thermal history can be reduced. Furthermore, this drying step sufficiently removes the solvent on the surface of the wet powder containing the target resin, and the resulting dried product can be redissolved with a small amount of solvent. Therefore, also in the solvent replacement step, the heat history for the resin can be reduced. Thus, in the present invention, since the heat history for the resin can be reduced comprehensively, the occurrence of defects due to the heat history for the resin can be sufficiently suppressed, and a high-quality photoresist resin A solution can be produced efficiently.

Hereinafter, the present invention will be described in detail.
The method for producing a photoresist resin solution of the present invention includes (1) a resin solution preparation step of preparing a resin solution containing a photoresist resin by polymerizing a polymerizable compound, and (2) the resin solution. A reprecipitation step of refining the resin contained therein to obtain a slurry; (3) a washing step of filtering the slurry and obtaining a wet powder by washing with a washing solvent; and (4) the wet powder. And (5) a solvent replacement step of re-dissolving the dry product and replacing the cleaning solvent with a photoresist solvent. In the drying step, The wet powder is dried in a constant rate drying region.

[1] Resin Solution Preparation Step In the resin solution preparation step, a resin solution containing a photoresist resin is prepared by polymerizing a polymerizable compound in the presence of a solvent (polymerization solvent).
The polymerizable compound is usually used for photolithography such as a radiation-sensitive resin composition for resist formation, a resin composition for forming an upper layer film or a lower layer film (antireflection film, etc.) in a multilayer resist. The polymeric compound (monomer) which has an ethylenically unsaturated bond used for manufacture of the resin for photoresists contained in a resin composition can be mentioned.

  Here, for example, the resin contained in the positive-type radiation-sensitive resin composition for resist formation is at least a repeating unit having a chemical structure that is decomposed by an acid and becomes soluble in an alkali developer, more specifically, And a repeating unit (1) having a chemical structure in which a non-polar substituent is dissociated by an acid and a polar group soluble in an alkali developer is expressed, and a polar group for enhancing adhesion to a substrate such as a semiconductor substrate The repeating unit (2) is an essential component, and includes a repeating unit (3) having a non-polar substituent for adjusting the solubility in a solvent or an alkali developer as necessary. .

  The repeating unit (1) that is decomposed by an acid and becomes alkali-soluble means a chemical structure generally used as a conventional resist, and a monomer having a chemical structure that is decomposed by an acid and becomes alkali-soluble. After polymerizing or polymerizing a monomer having an alkali-soluble chemical structure, the substituent having an alkali-soluble group (alkali-soluble group) in the alkali-soluble chemical structure is dissociated by an acid without being dissolved in the alkali. It can be obtained by protecting with a group (acid-dissociable protecting group).

Examples of the monomer having a chemical structure that becomes alkali-soluble when decomposed by an acid include compounds in which an acid-dissociable protecting group is bonded to a polymerizable compound containing an alkali-soluble substituent. And compounds having a phenolic hydroxyl group, a carboxyl group or a hydroxyfluoroalkyl group protected with an acid dissociable protecting group. Specifically, for example, hydroxystyrenes such as p-hydroxystyrene, m-hydroxystyrene, p-hydroxy-α-methylstyrene; acrylic acid, methacrylic acid, maleic acid, fumaric acid, α-trifluoromethylacrylic acid , 5-norbornene-2-carboxylic acid, 2-trifluoromethyl-5-norbornene-2-carboxylic acid, carboxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] carboxylic acids having an ethylenic double bond such as dodecyl methacrylate; p- (2-hydroxy-1,1,1,3,3,3-hexafluoro-2-propyl) styrene, 2- ( 4- (2-hydroxy-1,1,1,3,3,3-hexafluoro-2-propyl) cyclohexyl) -1,1,1,3,3,3-hexafluoropropyl acrylate, 2- (4 -(2-hydroxy-1,1,1,3,3,3-hexafluoro-2-propyl) cyclohexyl) -1,1,1,3,3,3-hexafluoropropyltrifluoromethyl acrylate, 5- Polymerizable compounds having a hydroxyfluoroalkyl group such as (2-hydroxy-1,1,1,3,3,3-hexafluoro-2-propyl) methyl-2-norbornene That.

Examples of the acid dissociable protecting group include a tert-butyl group, a tert-amyl group, a 1-methyl-1-cyclopentyl group, a 1-ethyl-1-cyclopentyl group, and a 1-methyl-1-cyclohexyl group. 1-ethyl-1-cyclohexyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 2-propyl-2-adamantyl group, 2- (1-adamantyl) -2-propyl group, 8-methyl-8-tricyclo [5.2.1.0 ^2,6 ] decanyl group, 8-ethyl-8-tricyclo [5.2.1.0 ^2,6 ] decanyl group, 8-methyl-8- Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecanyl group, 8-ethyl-8-tetracyclo [4.4.0.1 ^2,5 . 1 ^{7, 10} ] saturated hydrocarbon group such as dodecanyl group; 1-methoxyethyl group, 2-ethoxyethyl group, 1-iso-propoxyethyl group, 1-n-butoxyethyl group, 1-tert-butoxyethyl group, 1-cyclopentyloxyethyl group, 1-cyclohexyloxyethyl group, 1-tricyclo [5.2.1.0 ^2,6 ] decanyloxyethyl group, methoxymethyl group, ethoxymethyl group, iso-propoxymethyl group, n Oxygenated carbon such as -butoxymethyl group, tert-butoxymethyl group, cyclopentyloxymethyl group, cyclohexyloxymethyl group, tricyclo [5.2.1.0 ^2,6 ] decanyloxymethyl group, tert-butoxycarbonyl group A hydrogen group etc. are mentioned.

  After polymerizing a monomer having an alkali-soluble chemical structure and then protecting the alkali-soluble group in the alkali-soluble chemical structure with an acid-dissociable protecting group, the compound having the alkali-soluble group is directly polymerized. Then, an acid-dissociable protecting group can be introduced by reacting with a compound that gives a substituent that does not dissolve in an alkali such as vinyl ether or halogenated alkyl ether under an acid catalyst. Examples of the acid catalyst used in the reaction include p-toluenesulfonic acid, trifluoroacetic acid, and strongly acidic ion exchange resin.

  Examples of the monomer that gives the repeating unit (2) having a polar group for improving adhesion to the substrate include compounds having a phenolic hydroxyl group, a carboxyl group, or a hydroxyfluoroalkyl group as the polar group. Specifically, for example, as a polymerizable compound containing an alkali-soluble group, hydroxystyrenes described above, carboxylic acids having an ethylenic double bond, polymerizable compounds having a hydroxyfluoroalkyl group, and these In addition to the monomer further substituted with a polar group, a monomer having a polar group bonded to an alicyclic structure such as a norbornene ring or a tetracyclododecene ring can be used.

The polar group introduced into the repeating unit (2) as a substituent is particularly preferably one containing a lactone structure, such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, 1,3-cyclohexanecarbolactone. , 2,6-norbornanecarbolactone, 4-oxatricyclo [5.2.1.0 ^2,6 ] decan-3-one, and a substituent containing a lactone structure such as mevalonic acid δ-lactone.
Examples of polar groups other than the lactone structure include hydroxyalkyl groups such as a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, and a 3-hydroxy-1-adamantyl group.

Furthermore, as a monomer which gives the repeating unit (3) having a nonpolar substituent for adjusting the solubility in a resist solvent or an alkali developer, which is contained as necessary, styrene, α-methyl Aromatic compounds having an ethylenic double bond such as styrene, p-methylstyrene, and indene; acrylic acid, methacrylic acid, trifluoromethyl acrylic acid, norbornene carboxylic acid, 2-trifluoromethyl norbornene carboxylic acid, carboxytetracyclo [ 4.4.0.1 ^2,5 . 1 ^7,10 ] ester compound in which acid-stable nonpolar group is substituted for carboxylic acid having ethylenic double bond such as dodecyl methacrylate; alicyclic carbonization having ethylenic double bond such as norbornene and tetracyclododecene A hydrogen compound etc. are mentioned.
Examples of acid-stable nonpolar substituents that are ester-substituted for the carboxylic acid include methyl, ethyl, cyclopentyl, cyclohexyl, isobornyl, and tricyclo [5.2.1.0 ^2,6 ] decanyl. Group, 2-adamantyl group, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecyl group and the like.

These monomers may be used individually by 1 type in each of repeating unit (1), (2), and (3), and may be used in combination of 2 or more type.
The composition ratio of each repeating unit in the resin contained in the positive-type radiation-sensitive resin composition for resist formation can be selected within a range that does not impair the basic performance as a resist. That is, in general, the repeating unit (1) is preferably 10 to 70 mol%, more preferably 10 to 60 mol%. The composition ratio of the repeating unit (2) is preferably 30 to 90 mol%, more preferably 40 to 90 mol%, but for the monomer unit having the same polar group, 70 mol% The following is preferable. Furthermore, the composition ratio of the repeating unit (3) is preferably 50 mol% or less, more preferably 40 mol% or less.

  On the other hand, the resin contained in the resin composition for forming the upper layer film and the lower layer film (antireflection film, etc.) in the multilayer resist is the same as the chemistry of the resin contained in the positive type radiation sensitive resin composition for resist formation described above. A polymer having a chemical structure in which the repeating unit (1) which is decomposed with an acid and becomes alkali-soluble is removed from the structure. The composition ratio of each repeating unit in the resin is not particularly limited, and is appropriately adjusted depending on the intended use of the coating film. Generally, the composition ratio of the repeating unit (2) is selected from the range of 10 to 100 mol%, and the composition ratio of the repeating unit (3) is selected from the range of 0 to 90 mol%.

  Further, when the upper layer film or the lower layer film in the multilayer resist is used as an antireflection film, the resin needs to include a crosslinking point and a chemical structure that absorbs radiation irradiated in photolithography. The point includes reactive substituents that can be cross-linked by an ester bond, a urethane bond, or the like, such as a hydroxyl group, an amino group, a carboxyl group, or an epoxy group. Examples of the monomer containing a reactive substituent serving as a crosslinking point include hydroxystyrenes such as p-hydroxystyrene and m-hydroxystyrene, and the above-described polymerizable compounds such as the hydroxyl group, amino group, and carboxyl. A monomer substituted with a reactive substituent such as a group or an epoxy group can be appropriately used.

  The chemical structure that absorbs radiation varies depending on the wavelength of the radiation used. For example, for ArF excimer laser light, a chemical structure containing a benzene ring and its analogs is preferably used. Examples of the monomer having such a chemical structure include styrenes such as styrene, α-methylstyrene, p-methylstyrene, p-hydroxystyrene, m-hydroxystyrene, and derivatives thereof; substituted or unsubstituted phenyl (meta And aromatic-containing esters having an ethylenic double bond such as acrylate, substituted or unsubstituted naphthalene (meth) acrylate, substituted or unsubstituted anthracenemethyl (meth) acrylate, and the like. The monomer having a chemical structure that absorbs radiation may be introduced as either the repeating unit (2) or (3) depending on the presence or absence of a polar group, but the monomer having a chemical structure that absorbs radiation. Is preferably selected from the range of 10 to 100 mol%. In the present specification, “(meth) acrylate” means acrylate and methacrylate.

Moreover, the polymerization method of the said polymeric compound is not specifically limited, Well-known methods, such as solution polymerization, can be used.
The resin solution containing the photoresist resin uses, for example, a polymerization initiator, and further uses a chain transfer agent as necessary, and the above-described polymerizable compound (that is, polymerizable unsaturated monomer). Can be obtained by polymerizing in a suitable solvent.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), dimethyl 2,2′-azobisisobutyrate, 1,1′- Azo compounds such as azobis (cyclohexane-1-carbonitrile), 4,4′-azobis (4-cyanovaleric acid), decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, bis (3,5,5-trimethyl) Hexanoyl) peroxide, succinic acid peroxide, radical polymerization initiators such as organic peroxides such as tert-butylperoxy-2-ethylhexanoate. These polymerization initiators may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the chain transfer agent include thiol compounds such as dodecyl mercaptan, mercaptoethanol, mercaptopropanol, mercaptoacetic acid, mercaptopropionic acid, and 4,4-bis (trifluoromethyl) -4-hydroxy-1-mercaptobutane. be able to. These chain transfer agents may be used individually by 1 type, and may be used in combination of 2 or more type.

The amount of the polymerization initiator and chain transfer agent used is appropriately adjusted according to the production conditions such as the raw material monomer (polymerizable compound) used in the polymerization reaction, the polymerization initiator, the type of chain transfer agent, the polymerization temperature, the polymerization solvent, and the purification conditions. can do.
In general, if the weight average molecular weight of the resin is too high, the solubility in a solvent or an alkali developer used for forming a coating film tends to be low. On the other hand, when the weight average molecular weight is too low, the coating film performance tends to deteriorate. Therefore, the polystyrene-reduced weight average molecular weight (hereinafter also referred to as “Mw”) by gel permeation chromatography (GPC) is preferably adjusted to be in the range of 2000 to 40000, more preferably 3000 to 30000.

  The polymerization solvent used in the polymerization reaction is not particularly limited. For example, water, acetone, methyl ethyl ketone, methyl amyl ketone, cyclohexanone, methyl isobutyl ketone, tetrohydrofuran, dioxane, propylene glycol monomethyl ether, ethyl lactate, propylene glycol monomethyl It is preferable to use at least one of ether acetate, benzene and toluene. When these polymerization solvents are used, a photoresist resin with a high yield and fewer impurities can be obtained. Furthermore, the molecular weight distribution of the obtained photoresist resin can be narrowed, and the physical properties such as optical properties, chemical properties, coating properties and adhesion to the substrate or lower layer film required for resist films and antireflection films. Can be improved.

  Although the usage-amount of the said polymerization solvent is not specifically limited, Usually, it is 0.5-20 mass parts with respect to 1 mass part of monomers, Preferably it is 1-10 mass parts. If the amount of the solvent used is too small, the monomer may precipitate or become too viscous to keep the polymerization system uniform. On the other hand, when the amount of the solvent used is too large, the conversion rate of the raw material monomer may be insufficient, or the molecular weight of the polymer (resin) obtained may not be increased to a desired value.

Moreover, the reaction conditions in the said polymerization are not specifically limited, However, Reaction temperature is 40-120 degreeC normally, Preferably it is 50-100 degreeC. The reaction time is usually 1 to 48 hours, preferably 1 to 24 hours.
It is preferable that the density | concentration (solid content density | concentration) of the resin solution obtained in this resin solution preparation process is 1-80 mass%, More preferably, it is 5-50 mass%, More preferably, it is 10-50 mass%.

[2] Reprecipitation step In the reprecipitation step, impurities (especially low molecular components such as residual monomers, dimers, trimers, oligomers, etc.) are removed from the resin solution by a reprecipitation method. The resin is purified, and a slurry containing a photoresist resin is obtained. The analysis of the low molecular component can be performed by high performance liquid chromatography (HPLC).
This reprecipitation operation is not particularly limited, and can be performed according to a conventional method. Specifically, it can be performed by, for example, dropping the resin solution whose concentration is adjusted as necessary in a poor solvent (precipitation solvent).
In addition, the resin may be purified by repeating the precipitation operation twice or more using a good solvent as necessary.

  The poor solvent is not particularly limited as long as it precipitates a predetermined resin. For example, water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, pentane, hexane, heptane, cyclohexane, methylcyclohexane, It is preferable to use at least one of benzene and toluene. When precipitation purification is performed using these poor solvents, impurities remaining in the resin solution can be efficiently removed, and the yield of the resulting photoresist resin slurry can be improved.

  Moreover, the usage-amount of the said poor solvent is not specifically limited, It adjusts suitably with the kind of poor solvent, the kind of solvent in a resin solution, and its content. Specifically, for example, it is preferably 0.5 to 50 times, more preferably 1 to 30 times, still more preferably 2 to 20 times in terms of mass with respect to the total amount of the resin solution to be contacted with the poor solvent. Is double.

  Examples of the good solvent include ketones such as acetone, methyl ethyl ketone, methyl amyl ketone, and cyclohexanone; ethers such as tetrahydrofuran, dioxane, glyme, and propylene glycol monomethyl ether; esters such as ethyl acetate and ethyl lactate; propylene glycol methyl Examples include ether esters such as ether acetate, and lactones such as γ-butyrolactone. These good solvents may be used alone or in combination of two or more. The good solvent may be the same as or different from the polymerization solvent used in the resin solution preparation step described above.

  Moreover, it is preferable that the temperature of the slurry containing the resin for photoresists obtained by this reprecipitation process is 10-35 degreeC, More preferably, it is 15-35 degreeC, More preferably, it is 20-35 degreeC. The temperature of the slurry can be controlled by a temperature control device provided in the refining device, the temperature of the poor solvent used, and the like.

[3] Cleaning Step In the cleaning step, after the slurry obtained in the reprecipitation step is filtered, cleaning is performed using a cleaning solvent to obtain a wet powder containing a photoresist resin.
The method for filtering the slurry is not particularly limited, and in a conventional resin production method, the slurry can be filtered by a filtration device or the like used for solid-liquid separation of the resin-containing slurry. This filtration step may be performed under atmospheric pressure, or may be performed under pressure or reduced pressure using nitrogen gas or the like.

  Examples of the cleaning solvent used for the cleaning include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, and the like. . These cleaning solvents may be used alone or in combination of two or more. The cleaning solvent may be the same as or different from the poor solvent used in the reprecipitation step described above.

  The amount of the cleaning solvent used is not particularly limited, and is appropriately adjusted according to the type of cleaning solvent, the type of solvent contained in the slurry, and the content thereof. Specifically, for example, it is preferably 0.1 to 5 times, more preferably 0.5 to 3 times, and still more preferably 0.1 to 5 times in terms of mass with respect to the total amount of slurry to be brought into contact with the cleaning solvent. 5 to 1.5 times.

[4] Drying step In the drying step, a dry product containing a photoresist resin is obtained by drying the wet powder obtained in the above-described washing step.
This drying step is performed in the constant rate drying region. By performing drying in the constant rate drying region, only the solvent on the surface of the target resin contained in the wet powder is evaporated. That is, all of the amount of heat that flows in the drying process acts only on the evaporation of the solvent on the surface of the wet powder, and the wet powder changes at the wet bulb temperature.
Thus, by ending the drying process in the constant rate drying region, it is possible to save the heat history for the target resin without applying the heat history to the target resin after the transition to the decreasing rate drying region. .

Further, in the present invention, in order to reliably perform this drying step in the constant rate drying region, the wet powder actually prepared in advance is dried over a long period of time, and the liquid content of the dried product is determined every predetermined time. It is preferable to determine the range of the drying time that is the constant rate drying region by measuring the ratio of the liquid component contained when the entire dried product is 100% in terms of mass. Furthermore, the inflection point between the constant rate drying region and the reduced rate drying region can be obtained by measuring the liquid content at predetermined intervals in more detail.
In addition, the liquid content in a dried product or a wet powder can be measured by gas chromatography, a weight difference ratio before and after drying, or the like.

  The liquid content of the dried product obtained by this drying step is preferably 10% or less (usually the lower limit is 0.5% or more, particularly 0.8% or more), more preferably 8%. % Or less, more preferably 5% or less.

  Further, when the inflection point between the constant rate drying region and the reduction rate drying region is obtained, the liquid content of the dried product is x (%) when the liquid content at the inflection point is x (%). %), And it is preferable to dry until it becomes x + 10 (%) or less [especially x + 8 (%) or less, more preferably x + 5 (%) or less].

  Moreover, it is preferable that the said drying temperature (wet bulb temperature of the wet powder at the time of making it dry) is 70 degrees C or less, More preferably, it is 30-70 degreeC, More preferably, it is 40-60 degreeC. A temperature of 70 ° C. or lower is preferable because the cleaning solvent can be distilled off efficiently and with little heat history.

[5] Solvent replacement step In the solvent replacement step, after the redissolved product obtained in the drying step is redissolved, solvent replacement is performed using a photoresist solvent. Specifically, for example, after the dried product is dissolved in a re-dissolving solvent (hereinafter also referred to as “re-dissolving solvent”), a photoresist solvent is further added, and the residue is left by heating and concentrating. The washing solvent and the redissolving solvent are distilled off to perform solvent replacement.

Examples of the redissolving solvent include methyl ethyl ketone, methyl amyl ketone, cyclohexanone, methyl isobutyl ketone, tetrohydrofuran, and dioxane. These may be used alone or in combination of two or more.
As the redissolving solvent, a solvent having a boiling point lower than that of a photoresist solvent described later is selected and used.

  The temperature during the re-dissolution is preferably 15 to 50 ° C, more preferably 20 to 40 ° C, and still more preferably 25 to 35 ° C.

  Moreover, the usage-amount of the said solvent for re-dissolution is not specifically limited, It adjusts suitably with the kind of solvent for re-dissolution, the kind of solvent contained in a dried material, and its content. Specifically, for example, it is preferably 1 to 10 times, more preferably 1.5 to 5 times, more preferably 2 with respect to the total amount of the dried product to be brought into contact with the redissolving solvent. ~ 3 times.

  Examples of the photoresist solvent include ketones such as acetone, methyl ethyl ketone, methyl amyl ketone, and cyclohexanone; ethers such as tetrahydrofuran, dioxane, glyme, and propylene glycol monomethyl ether; esters such as ethyl acetate and ethyl lactate; Examples include ether esters such as glycol methyl ether acetate, and lactones such as γ-butyrolactone. These solvents may be used alone or in combination of two or more.

Moreover, it is preferable that the heating temperature at the time of performing the said heat concentration is 30-80 degreeC, More preferably, it is 40-70 degreeC, More preferably, it is 50-60 degreeC.
In addition, this heating concentration process may be performed under atmospheric pressure, and may be performed under reduced pressure. In particular, it is preferable to carry out under reduced pressure from the viewpoint that the solvent replacement can be carried out efficiently and with little heat history.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

[1] Production of photoresist resin solution (Example 1)
(1) Resin Solution Preparation Step In a three-necked flask with a 3000 mL Dimroth tube, 415 g of methyl ethyl ketone (MEK) as a polymerization solvent was sufficiently substituted with nitrogen, and then heated to 80 ° C. while stirring with a three-one motor. Then, 171 g of 5-methacryloyloxy-2,6-norbornanecarbolactone (NLM) and 226 g of 2-methyl-2-adamantyl methacrylate (MAdMA) were dissolved in 808 g of MEK, and 7.1 g of azobisisobutyronitrile. The solution dissolved in 36 g of MEK was added dropwise over 3 hours using a dropping funnel. After completion of the dropwise addition, the mixture was further aged for 3 hours, and then cooled to room temperature to prepare a resin solution containing a photoresist resin (crude resin). As a result of measurement using high performance liquid chromatography, the conversion rate of the monomer was 85%.

(2) Reprecipitation step While stirring 1656 g of the obtained resin solution (solid content concentration: about 25% by mass) in 8280 g of methanol (poor solvent), the solution was added dropwise at a dropping rate of 27.6 g / min for about 1 hour. By carrying out purification by precipitation, a slurry containing a photoresist resin was obtained.

(3) Washing Step After the obtained slurry was filtered, it was washed twice with 1656 g of methanol (washing solvent) to obtain a wet powder containing the target resin.

(3-1) Measurement of liquid content Result of measurement by gas chromatography after dissolving 0.1 g of the obtained wet powder (wet polymer) in 3 g of propylene glycol monomethyl ether acetate (hereinafter referred to as “PEGMEA”) The wet powder liquid content was 50%.
Next, 40 g of wet powder having a liquid content of 40% was dried at a temperature of 60 ° C. in a vacuum dryer. And the liquid content of the wet powder was measured every 5 minutes, and the results are shown in Table 1.
From this result, it can be inferred that there is an inflection point between the constant rate drying region and the decreasing rate drying region in the vicinity of 30 minutes, and the drying time exceeds 0 minutes, and it is surely constant until about 20 minutes. It was confirmed that it was a rate drying region.

(4) Drying step 40 g of wet polymer with a liquid content of 50% obtained by the washing step is dried at 60 ° C. for 15 minutes (ie, dried in a constant rate drying region), and a certain amount of solvent on the wet polymer surface is obtained. Removal of 22 g of a dried product having a liquid content of 8% was obtained.

(5) Solvent replacement step 22 g of the obtained dried product and 60 g of methyl ethyl ketone were mixed and stirred at 30 ° C. for 12 minutes to completely dissolve the dried product.
Next, the obtained solution was dissolved in 65 g of PEGMEA, and heated and concentrated under reduced pressure at 60 ° C. for 15 minutes to obtain 66 g of a photoresist resin solution (solid content concentration: about 30% by mass).
And when the amount of methanol in the obtained resin solution for photoresists and the amount of methyl ketone were measured with the gas chromatography, respectively, neither methanol nor methyl ketone was detected.
Further, in the production of the resin of Example 1, the drying time in the drying step, the drying region, the liquid content after drying, the amount of the solvent for redissolving in the solvent replacement step, the time required for dissolution, the resist solvent Table 2 shows the amount of the used, solvent replacement time, total heating time in the drying step and solvent replacement step.

[2] Manufacture of photoresist resin (Comparative Example 1)
40 g of wet polymer having a liquid content of 50% obtained in the same manner as in Example 1 was mixed with 200 g of methyl ethyl ketone without drying at all and stirred at 30 ° C. for 15 minutes to completely dissolve the wet polymer. .
Next, the obtained solution was dissolved in 100 g of PEGMEA, and heated and concentrated under reduced pressure at 60 ° C. for 60 minutes to obtain 66 g of a photoresist resin solution (solid content concentration: about 30% by mass).
And when the amount of methanol in the obtained resin solution for photoresists and the amount of methyl ketone were measured with the gas chromatography, respectively, neither methanol nor methyl ketone was detected.
Further, in the production of the resin of Comparative Example 1, the drying time in the drying step, the drying region, the liquid content after drying, the amount of solvent used for redissolving in the solvent replacement step, the time required for dissolution, the resist solvent Table 2 also shows the total heating time in the use amount, solvent replacement time, drying step and solvent replacement step.

[3] Manufacture of photoresist resin (Comparative Example 2)
40 g of a wet polymer with a liquid content of 50% obtained in the same manner as in Example 1 was dried at 60 ° C. for 1440 minutes (that is, dried in a constant rate drying region and a decreasing rate drying region), and 20 g of photoresist resin. (Liquid content; 0.4%) was obtained. Thereafter, the obtained resin was dissolved in 46 g of PEGMEA to obtain a resin solution for photoresist.
And when the amount of methanol in the obtained photoresist resin solution was measured by gas chromatography, 0.5 mass% methanol was detected when the photoresist resin was 100 mass%.
Table 2 also shows the drying time in the drying process, the drying region, the liquid content after drying, and the total heating time in the production of the resin of Comparative Example 2.

  According to Table 2, in Example 1 where the drying of the wet powder in the drying process was performed only in the constant rate drying region, the heat history for the target resin can be reduced comprehensively, and the photoresist resin solution It was found that can be manufactured efficiently.

Claims (3)

A method for producing a photoresist resin solution, comprising:
(1) a resin solution preparation step of preparing a resin solution containing a photoresist resin by polymerizing a polymerizable compound;
(2) a reprecipitation step of refining the resin contained in the resin solution to obtain a slurry;
(3) a washing step of filtering the slurry and obtaining a wet powder by washing with a washing solvent;
(4) a drying step of drying the wet powder to obtain a dried product;
(5) a solvent replacement step of re-dissolving the dried product and replacing the cleaning solvent with a photoresist solvent,
In the drying step, the wet powder is dried in a constant rate drying region.   The method for producing a photoresist resin solution according to claim 1, wherein the liquid content of the dried product obtained by the drying step is 10% or less.   The method for producing a photoresist resin solution according to claim 1, wherein a drying temperature in the drying step is 70 ° C. or lower.