Method for producing refined chemical solution

Abstract

Provided is a method for producing a refined chemical liquid used in manufacturing a semiconductor element, the refined chemical liquid being produced by removing minute foreign matter through filtration using a porous membrane to refine a crude chemical liquid.　In the production of a refined chemical liquid used in manufacturing a semiconductor element, a crude chemical liquid is filtered by using, as a filter, a porous polyamide film which has a plurality of spherical holes therein and in which the plurality of spherical holes are connected to adjacent spherical holes to form communication holes.

Description

Method for producing purified chemical solution

[0001] The present invention relates to a method for purifying a crude chemical solution to produce a purified chemical solution used in the manufacture of semiconductor devices.

[0002] In recent years, advances in lithography technology have led to rapid miniaturization of patterns in the manufacturing of semiconductor devices and liquid crystal display elements.

[0003] As patterns become finer, resist materials are required to have improved lithography properties in various ways, as well as to suppress the occurrence of defects (surface defects). Here, "defect" refers to any defects that can be detected when observing a resist pattern from directly above after development using, for example, a surface defect observation device manufactured by KLA Tencor (product name "KLA"). These defects include, for example, defects caused by the adhesion of foreign matter or precipitates to the surface of the resist pattern after development, such as scum (resist residue), bubbles, and dust; defects related to the pattern shape, such as bridging between line patterns and filling of holes in contact hole patterns; and color unevenness of the pattern.

[0004] Conventionally, resist compositions used for manufacturing semiconductor elements and liquid crystal display elements are generally purified by passing them through a filter to remove foreign matter (for example, Patent Document 1).

[0005] Japanese Patent Publication No. 2017-226836

[0006] The polyamide resin film described in Patent Document 1 is manufactured by a phase separation method. The phase separation method is a method that utilizes external stimuli such as cooling, contact with a non-solvent, evaporation of the solvent, and chemical reactions such as polymerization. Therefore, it is difficult to control the shape of the pores in the porous film, and there is a problem in that it is difficult to remove minute foreign matter.

[0007] The present invention has been made in view of the above-mentioned problems, and aims to provide a method for producing a purified chemical solution used in the manufacture of semiconductor devices by purifying a crude chemical solution by removing minute foreign matter through filtration using a porous membrane.

[0008] The inventors of the present invention have found that the above problems can be solved in the production of purified chemical solutions used in the manufacture of semiconductor devices by filtering the crude chemical solution using a porous polyamide film as a filter, the film having multiple spherical pores inside, and the multiple spherical pores being connected to adjacent spherical pores to form communicating pores. This led to the completion of the present invention.

[0009] More specifically, the present invention relates to a method for purifying a crude chemical solution to produce a purified chemical solution used in the manufacture of semiconductor devices, comprising: filtering the crude chemical solution using a porous polyamide film as a filter; and recovering the liquid that has passed through the filter as a purified chemical solution, wherein the porous polyamide film has a plurality of spherical pores inside, and the plurality of spherical pores are connected to adjacent spherical pores to form communicating pores.

[0010] According to the present invention, a method is provided for producing a purified chemical solution used in the manufacture of semiconductor devices by purifying a crude chemical solution by removing minute foreign matter through filtration using a porous membrane.

[0011] ≪Method for producing purified chemical solution≫ The method for producing purified chemical solution is used to produce purified chemical solution for use in the manufacture of semiconductor devices.

[0012] A method for producing a purified drug solution includes filtering a crude drug solution using a porous polyamide film as a filter, and recovering the liquid that has passed through the filter as a purified drug solution.

[0013] Hereafter, the filtration of the crude chemical solution using a porous polyamide film as a filter will also be referred to as the "filtration process." The recovery of the liquid that has passed through the filter as the purified chemical solution will also be referred to as the "recovery process."

[0014] <Filtration Process> In the filtration process, the crude chemical solution is filtered using a porous polyamide film as a filter.

[0015] [Chemical Solution] A crude chemical solution is purified to produce a purified chemical solution used in the manufacture of semiconductor devices. The chemical solution used in the manufacture of semiconductor devices is not particularly limited. Examples of chemical solutions include chemical solutions for forming protective films to modify substrates, chemical solutions for cleaning silicon wafers, chemical solutions containing photosensitive materials such as resist compositions, anti-reflective film forming materials such as SiARC and BARC, and raw material chemical solutions for photosensitive materials such as resin solutions.

[0016] Examples of photosensitive materials include photosensitive resin compositions that become sparingly soluble in a developer upon exposure, or readily soluble in a developer upon exposure. A photosensitive resin composition that becomes sparingly soluble in a developer upon exposure is a so-called negative-type photosensitive resin composition. A photosensitive resin composition that becomes readily soluble in a developer upon exposure is a so-called positive-type photosensitive composition.

[0017] A preferred positive-type photosensitive resin composition is one which comprises an acid generator (A) that generates acid upon irradiation with active light or radiation, a resin (B) whose solubility in alkali increases due to the action of the acid, and an organic solvent (C).

[0018] By filtering these chemical solutions using the aforementioned porous polyamide film, metallic impurities, such as iron and zinc, and other minute foreign substances can be removed with a very high removal rate.

[0019] [Porous Polyamide Film] A porous polyamide film has multiple spherical pores inside. These multiple spherical pores are connected to adjacent spherical pores, forming interconnected pores.

[0020] In the porous polyamide film described above, the pore size and pore shape are controlled, resulting in a large specific surface area. As a result, when filtering crude chemical solutions using the porous polyamide film described above, minute impurities in the fluid can be effectively removed.

[0021] (Method for producing porous polyamide film) The method for producing porous polyamide film is not particularly limited as long as it can produce a porous polyamide film that satisfies the above-mentioned predetermined conditions.

[0022] A preferred method for producing a porous polyamide film includes: melt-kneading a thermoplastic polyamide resin and spherical inorganic fine particles to obtain a thermoplastic polyamide resin composition in which inorganic fine particles are dispersed in the thermoplastic polyamide resin; forming the thermoplastic polyamide resin composition into a film by melt processing to obtain a polyamide resin composition film; and removing the inorganic fine particles from the polyamide resin composition film.

[0023] The shape of the inorganic microparticles is spherical. The spherical pores in the porous polyamide film are formed when spherical inorganic microparticles are removed from the thermoplastic polyamide resin composition. Therefore, the spherical pores have the same shape and size as the inorganic microparticles. In other words, the shape of the pores in the porous polyamide film is controlled to be spherical by using spherical inorganic microparticles. Furthermore, the pore diameter in the porous polyamide film can be controlled by appropriately selecting the particle size of the spherical inorganic microparticles. Moreover, by using spherical inorganic microparticles with a narrow particle size distribution, a porous polyamide film with a narrow pore size distribution can be obtained.

[0024] Hereinafter, the process of melt-kneading a thermoplastic polyamide resin with inorganic fine particles to obtain a thermoplastic polyamide resin composition in which inorganic fine particles are dispersed within the thermoplastic polyamide resin will also be referred to as the melt-kneading process. The process of forming the thermoplastic polyamide resin composition into a film by melt processing to obtain a polyamide resin composition film will also be referred to as the melt-film formation process. The process of removing inorganic fine particles from the polyamide resin composition film will also be referred to as the inorganic fine particle removal process.

[0025] (Melting and kneading process) In the melting and kneading process, a thermoplastic polyamide resin and inorganic fine particles are melted and kneaded to obtain a thermoplastic polyamide resin composition in which inorganic fine particles are dispersed in the thermoplastic polyamide resin.

[0026] The temperature at which melt mixing is performed is not particularly limited, as long as it is the temperature at which the thermoplastic polyamide resin melts. For example, melt mixing is performed at a temperature 5°C to 100°C higher than the melting point of the thermoplastic polyamide resin. When multiple thermoplastic polyamide resins are used in a mixture, melt mixing is performed at a temperature 5°C to 100°C higher than the melting point of the thermoplastic polyamide resin with the highest melting point among the multiple types of thermoplastic polyamide resins. Here, the melting point of the polyamide resin is measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121.

[0027] The method for melt-mixing thermoplastic polyamide resin and inorganic fine particles is not particularly limited. Melt-mixing is usually carried out using an extruder such as a single-screw extruder or a twin-screw extruder.

[0028] When thermoplastic polyamide resin and inorganic fine particles are melt-kneaded, plasticizers, release agents, and other additives may be used. However, when forming a film from a thermoplastic polyamide resin composition using the method described above, it is preferable not to use plasticizers, release agents, or other additives. The porous polyamide film obtained by removing inorganic fine particles from the polyamide resin composition film is used for filtering crude chemical solutions. Crude chemical solutions often contain organic solvents. When filtering a chemical solution containing an organic solvent using a porous polyamide film, if the porous polyamide film contains plasticizers, release agents, or other additives, there is a risk that the plasticizers, release agents, or other additives may leach into the filtered chemical solution.

[0029] The form of the thermoplastic polyamide resin composition obtained by melt-mixing, in which inorganic fine particles are dispersed in a thermoplastic polyamide, is not particularly limited. Examples of forms of thermoplastic polyamide resin compositions include flakes, powders, and pellets.

[0030] A thermoplastic polyamide resin composition, obtained by melt-mixing, in which inorganic fine particles are dispersed in thermoplastic polyamide, is typically extruded from an extruder in the form of strands. The stranded polyamide resin composition solidifies as it cools and is then cut into the desired size to form pellets.

[0031] • Thermoplastic polyamide resin Any known thermoplastic polyamide resin can be used without particular limitation. The thermoplastic polyamide resin may be a ring-opening polymer of lactam or a condensed polymer of hydroxycarboxylic acid. The ring-opening polymer of lactam and the condensed polymer of hydroxycarboxylic acid may be homopolymers or copolymers. Furthermore, the thermoplastic polyamide resin may be a condensed polymer obtained by the condensation polymerization of a diamine component and a dicarboxylic acid component. The condensed polymer obtained by the condensation polymerization of a diamine component and a dicarboxylic acid component may contain two or more constituent units derived from the diamine component, or two or more constituent units derived from the dicarboxylic acid component. The thermoplastic polyamide resin may be a polymer obtained by polymerization of lactam and / or hydroxycarboxylic acid, and a diamine component and a dicarboxylic acid component. Two or more lactams, hydroxycarboxylic acids, diamine components, and dicarboxylic acid components may each be used in combination.

[0032] Specific examples of thermoplastic polyamide resins include aliphatic polyamides such as nylon 6, nylon 7, nylon 9, nylon 11, nylon 12, nylon 26, nylon 46, nylon 66, nylon 610, nylon 612, nylon 86, nylon 108, nylon 6 / 12, nylon 6 / 9, nylon 6 / 66, nylon 12 / 66, nylon 26 / 66, nylon 66 / 610, and nylon 6 / 66 / 610). The names of these nylons are based on JIS K 6920-1. Furthermore, the raw materials for the above nylons are not particularly limited. For example, nylon 6 is generally produced by ring-opening polymerization of caprolactam. However, nylon 6 is not limited to ring-opening polymers of caprolactam, but may also be a condensation polymer of 6-aminohexanoic acid.

[0033] In addition, specific examples of the thermoplastic polyamide resin include polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymetaxylylene adipamide, hexamethylene isophthalamide / terephthalamide copolymer, poly-p-phenylene terephthalamide, and aromatic polyamides such as poly-p-phenylene·3,4'-oxydiphenylene terephthalamide, and various amorphous polyamides.

[0034] The thermoplastic polyamide resin described above may be subjected to various known modifications.

[0035] - Inorganic fine particles The material of the inorganic fine particles is not particularly limited as long as it can be removed from the polyamide resin composition film when producing the porous polyamide film using the polyamide resin composition film. Suitable examples of the material of the inorganic fine particles include, for example, metal oxides such as silica (silicon dioxide), titanium oxide, and alumina (Al ,

[0039] ,

[0038] ,

[0037] , ,

[0036] , , O ３ ) and metals such as iron and iron-nickel alloys. For spherical fine particles made of metal, they can be produced, for example, by the method described in Journal of Alloys and Compounds, Volume 480, Issue 2, 8 July 2009, Pages 529-533.

[0036] The shape of the inorganic fine particles is spherical. Here, the spherical shape is not limited to a geometrically perfect spherical shape, but any shape that can be recognized as being close to a spherical shape when visually observing a microscopic image is acceptable.

[0037] As the spherical inorganic fine particles, for example, colloidal silica fine particles are preferred. As the colloidal silica, monodisperse spherical silica particles are preferred because they can form uniform pores in the porous polyamide film.

[0038] In the porous polyamide film, the average pore diameter of the spherical pores is 10 nm or more and 200 nm or less. The average pore diameter of the spherical pores can be adjusted by adjusting the volume average particle diameter of the inorganic fine particles.

[0039] The average pore diameter of the spherical pores is preferably 10 nm or more and 200 nm or less, more preferably 15 nm or more and 100 nm or less, and particularly preferably 15 nm or more and 50 nm. The average pore diameter is the average pore diameter measured by a porosimeter.

[0040] The pore size distribution is the pore size distribution measured by a porosimeter. The upper limit of the difference between the maximum value of the pore size range of the fraction with the largest pore diameter where pores are distributed and the minimum value of the pore size range of the fraction with the smallest pore diameter where pores are distributed is not particularly limited, and may be 30 nm or less, or may be 20 nm or less.

[0041] The volume average particle diameter of the inorganic fine particles is, for example, preferably 0.03 μm or more and 1.0 μm or less, more preferably 0.05 μm or more and 0.5 μm or less, and still more preferably 0.1 μm or more and 0.5 μm or less. The volume average particle diameter of the inorganic fine particles is the so-called D50. D50 means the particle diameter at the integrated value of 50% in the volume-based particle size distribution determined by the laser diffraction / scattering method.

[0042] The inorganic fine particles may be used alone or in combination of two or more.

[0043] The surface area of a region of 1 m ２ on the main surface of the porous polyamide film is preferably 1000 m ２ or more and 6000 m ２ or less. The surface area of a region of 1 m ２ on the main surface of the porous polyamide film can be increased by increasing the ratio of the mass of the inorganic fine particles to the mass in the polyamide resin composition or by reducing the volume average particle diameter of the inorganic fine particles. Therefore, the amount of the inorganic fine particles used is appropriately determined in consideration of the volume average particle diameter of the inorganic fine particles and the surface area of a region of 1 m[[ID=z19]] ２ on the main surface of the obtained porous polyamide film.

[0044] The amount of inorganic fine particles used is preferably, for example, 50% to 70% by mass, more preferably 55% to 70% by mass, and even more preferably 60% to 70% by mass, relative to the mass of the thermoplastic polyamide resin composition. Accordingly, in the polyamide resin composition film, the inorganic fine particle content is preferably 50% to 70% by mass, more preferably 55% to 70% by mass, and even more preferably 60% to 70% by mass, relative to the mass of the thermoplastic polyamide resin composition. By using an amount of inorganic fine particles within the above range, it is easy to obtain a non-brittle and uniform polyamide resin composition, and when obtaining a porous polyamide film by the method described later, it is easy to obtain a porous polyamide film having the desired porous structure.

[0045] Other components: The thermoplastic polyamide resin composition may, if necessary, contain other thermoplastic resins other than the thermoplastic polyamide resin and various additives, along with the thermoplastic polyamide resin and inorganic fine particles. When the thermoplastic polyamide resin composition contains other thermoplastic polyamide resins along with the thermoplastic polyamide resin, the ratio of the mass of the other thermoplastic resins to the mass of the resin components contained in the thermoplastic polyamide resin composition is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. Examples of additives include colorants, antioxidants, ultraviolet absorbers, surfactants, and silane coupling agents.

[0046] When forming a thermoplastic polyamide resin composition into a film using the method described above, it is preferable that the above-mentioned additives are not used. The porous polyamide film obtained by removing inorganic fine particles from the polyamide resin composition film is used for filtering crude chemical solutions. Crude chemical solutions often contain organic solvents. When filtering a chemical solution containing an organic solvent using a porous polyamide film, if the porous polyamide film contains the above-mentioned additives, there is a risk that the additives may leach into the filtered chemical solution.

[0047] (Melting film formation process) In the melting film formation process, the thermoplastic polyamide resin composition is formed into a film by melting to obtain a polyamide resin composition film.

[0048] Melting methods for obtaining film include the T-die method, the inflation method, and the calendering method. Among these methods, the T-die method is preferred because it allows for easy adjustment of the film thickness and offers excellent film productivity.

[0049] The melting temperature for film formation is determined appropriately, taking into account the type of melting method, the melting point and glass transition temperature of the thermoplastic polyamide, and the thickness of the film.

[0050] The thickness of the polyamide resin composition film is preferably 20 μm or more and 200 μm or less, more preferably 40 μm or more and 150 μm or less, and even more preferably 50 μm or more and 100 μm or less.

[0051] By the above method, a polyamide composition film is obtained, which consists of a thermoplastic polyamide resin composition in which inorganic particles are dispersed in a thermoplastic polyamide resin.

[0052] (Inorganic Fine Particle Removal Process) A porous polyamide film is obtained by removing inorganic fine particles from the polyamide resin composition film obtained by the above method. The thickness of the porous polyamide film obtained through the inorganic fine particle removal process is preferably 20 μm to 200 μm, more preferably 40 μm to 150 μm, and even more preferably 50 μm to 100 μm, similar to the thickness of the polyamide resin composition film.

[0053] The method for removing inorganic fine particles from a polyamide resin composition film is not particularly limited. A preferred method for removing inorganic fine particles from a polyamide resin composition film is to bring the polyamide resin composition film into contact with a liquid capable of dissolving inorganic fine particles. While the method for bringing the polyamide resin composition film into contact with a liquid capable of dissolving inorganic fine particles is not particularly limited, a preferred method is to immerse the polyamide resin composition film in a liquid capable of dissolving inorganic fine particles.

[0054] For example, if the inorganic fine particles are silica fine particles, the silica fine particles can be removed from the polyamide resin composition film by contacting the film with an aqueous solution of hydrogen fluoride (hydrofluoric acid). Furthermore, if the inorganic fine particles are metal fine particles such as iron fine particles or iron-nickel alloy fine particles, the metal fine particles can be removed from the polyamide resin composition film by contacting the film with hydrochloric acid solution.

[0055] A porous polyamide film is obtained by removing inorganic fine particles from a polyamide resin composition film using the method described above, and then washing and drying the resulting film as needed. The washing method is not particularly limited. Typically, washing is performed using water or organic solvents such as methanol and ethanol. The drying method is not particularly limited. Drying can be performed by methods such as heating, vacuum drying, or standing in the air.

[0056] A filter made of porous polyamide film is used to purify crude drug solutions containing the aforementioned impurities. This filter is particularly suitable for filtering crude drug solutions containing fine particles. Fine particles are defined as particles with a diameter of 0.135 μm or more in 1 mL of sample, as measured using a light scattering particle size counter.

[0057] <Recovery Process> In the recovery process, the liquid that has passed through the filter is recovered as a purified chemical solution. It is preferable that the amount of metal impurities in the recovered purified chemical solution is less than the amount of metal impurities in the crude chemical solution. It is also preferable that the number of fine particles in the recovered purified chemical solution is less than the number of fine particles in the crude chemical solution. The number of fine particles is the number of particles with a diameter of 0.135 μm or more in 1 mL of sample, measured using a light scattering type liquid particle size counter.

[0058] As described above, the present inventors provide the following [1] to [7]. [1] A method for purifying a crude chemical solution to produce a purified chemical solution used in the manufacture of semiconductor devices, comprising: filtering the crude chemical solution using a porous polyamide film as a filter; and recovering the liquid that has passed through the filter as the purified chemical solution, wherein the porous polyamide film has a plurality of spherical pores inside, and the plurality of spherical pores are connected to adjacent spherical pores to form a communication pore. [2] The method according to [1], wherein the amount of metal impurities contained in the purified chemical solution is less than the amount of metal impurities contained in the crude chemical solution. [3] The number of fine particles contained in the purified chemical solution is less than the number of fine particles contained in the crude chemical solution, and the number of fine particles is the number of particles having a diameter of 0.135 μm or more in 1 mL of the sample, measured using a light scattering type liquid particle size counter. The method according to [1] or [2]. [4] The method according to [3], wherein the purified chemical solution is a photosensitive resin composition that becomes less soluble or more soluble in a developer upon exposure. [5] The method according to [4], wherein the photosensitive resin composition contains an acid generator (A) that generates an acid upon irradiation with actinic rays or radiation, a resin (B) whose solubility in an alkali increases by the action of the acid, and an organic solvent (C). [6] The method according to any one of [1] to [5], wherein the average pore diameter of the spherical pores is 10 nm or more and 200 nm or less. [7] The surface area of an area of 1 m ２ on the main surface of the porous polyamide film is 1000 m ２ or more and 6000 m ２ or less. The method according to any one of [1] to [6].

[0059] Hereinafter, the present invention will be described in detail by way of examples, but the scope of the present invention is not limited to these examples.

[0060] [Examples 1-4] The amounts of nylon 6 and spherical silica fine particles listed in Table 1 were melt-kneaded using a twin-screw extruder (HK-25D, Parker Corporation) at a cylinder temperature of 270°C and a rotation speed of 200 rpm. The volume-average particle size of the spherical silica fine particles is as shown in Table 1. The polyamide resin composition discharged from the extruder in strand form was cut while being cooled and solidified to obtain the polyamide resin composition of each example as pellets.

[0061] The polyamide resin compositions of each example obtained as described above were extruded using a T-die extruder (Laboplastmill, Toyo Seiki Seisakusho Co., Ltd.) with the polyamide resin composition temperature set to 270°C and the die lip temperature to 280°C, and extruded at a rotation speed of 50 rpm to form films, thereby obtaining polyamide resin composition films of each example. The film thickness of the polyamide resin composition films was 100 μm.

[0062] The polyamide resin composition film obtained as described above was immersed in 10% by mass hydrofluoric acid at 25°C (room temperature) for 5 minutes to remove silica particles from the polyamide resin composition film. After the removal of the silica particles, the film was removed from the hydrofluoric acid, washed with pure water, and then dried to obtain the porous polyamide film of each example. The thickness of the porous polyamide film was 100 μm. When the cross-sections of the porous polyamide films of each example obtained were observed with a scanning electron microscope (SEM), it was found that interconnected pores, in which spherical pores are connected to each other, were formed inside all of the porous polyamide films.

[0063] [Comparative Example 1] A formic acid solution of nylon 6 containing nylon 6 at a concentration of 10% by mass was applied to a PET (polyethylene terephthalate) substrate using an applicator to form a coating film. The PET substrate with the coating film was immersed in pure water at 25°C for 5 minutes to induce phase separation in the nylon 6. After immersion for a predetermined time, the PET substrate with the porous polyamide film formed by the phase separation was removed from the pure water. The porous polyamide film on the PET substrate removed from the pure water was washed with pure water, dried, and then peeled off from the PET substrate to obtain the porous polyamide film of Comparative Example 1. The thickness of the porous polyamide film was 100 μm. When the cross-section of the obtained porous polyamide film was observed with a scanning electron microscope (SEM), a structure in which irregularly shaped pores were interconnected was observed inside the porous polyamide film.

[0064] [Comparative Example 2] A porous polyamide film was obtained in the same manner as in Comparative Example 1, except that the resin concentration of nylon 6 was changed to 20% by mass. The thickness of the porous polyamide film was 100 μm. When the cross-section of the obtained porous polyamide film was observed with a scanning electron microscope (SEM), a structure in which irregularly shaped pores were interconnected was observed inside the porous polyamide film.

[0065] [Comparative Example 3] Pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA) were polymerized in N,N-dimethylacetamide in a molar ratio of 1:1 according to a conventional method to obtain a polyamic acid solution with a solid content of 20% by mass. To the obtained polyamic acid solution, a silica dispersion (containing 0.5% by mass of dispersant relative to silica) was added so that the ratio of the mass of polyamic acid to the mass of silica (fine particles (B)) was 42:58 as polyamic acid:silica fine particles (mass ratio). Furthermore, organic solvent (1) and organic solvent (2) were added to the slurry containing the polyamic acid and silica fine particles, respectively, so that the solvent composition in the varnish for forming porous polyimide film was 45:55 as organic solvent (1):organic solvent (2) (mass ratio). The obtained mixture was dispersed in a 1000 mL container by stirring with a stirring blade at 4000 rpm for 30 minutes. Subsequently, a 60 μm diameter (cross-sectional area 2826 μm) manufactured by Yoshida Machinery Industry Co., Ltd. ２ Using a dispersion apparatus equipped with a channel, the mixed liquid was passed through the channel at a pressure of 200 MPa for 10 dispersion treatments to prepare a polyimide porous film forming varnish with a solid content of 20% by mass. The following organic solvent, dispersant, and silica microparticles were used: Organic solvent (1): N-methyl-2-pyrrolidone Organic solvent (2): N,N-dimethylacetamide (DMAc) Dispersant: Polyoxyethylene secondary alkyl ether-based dispersant Silica microparticles: Silica microparticles with a volume-average particle size of 100 nm

[0066] The obtained polyimide film porous film forming varnish was applied to a polyethylene terephthalate (PET) film substrate using an applicator and dried at 90°C for 5 minutes to form a composite film on the substrate (composite film formation step). After peeling this composite film (unfired composite film) from the substrate, it was placed in an oven and fired at 380°C for 15 minutes to complete the imidization and obtain a resin-microparticle composite film (firing step). The peeled resin-microparticle composite film was immersed in hydrogen fluoride (HF) for 10 minutes to remove silica microparticles contained in the film (microparticle removal step). After that, it was washed with water and dried to obtain a porous polyimide film with a film thickness of 40 μm.

[0067] The average pore size of the porous polyamide films or porous polyimide films obtained in Examples 1 to 4 and Comparative Examples 1 to 3 was measured using a liquid porometer (manufactured by Porometer) according to the method described above. Furthermore, the N ２ Based on the specific surface area measured by the BET method using gas, the area of ​​the main surface of the porous film is 1 m². ２ The surface area of ​​the region was calculated. These measurement results are shown in Table 1.

[0068] Furthermore, the porous polyamide film or porous polyimide film obtained in Examples 1 to 4 and Comparative Examples 1 to 3 was used to filter the chemical solution, and the following evaluations were performed.

[0069] In the evaluation of the drug history by filtration, the following resist composition was used as the crude drug solution. The resist composition used as the crude drug solution had the following formula as its resin component: 100 parts by mass of a copolymer represented by the following formula, and the following formula as an acid generator: 19 parts by mass of a compound represented by the following formula, and an acid diffusion control agent with the following formula: The solution consists of 6 parts by mass of the compound represented by [formula] and 2,500 parts by mass of a mixed solvent of propylene glycol monomethyl ether acetate / propylene glycol monomethyl ether = 60 / 40 (mass ratio).

[0070] The above resin contained in the crude chemical solution has a weight-average molecular weight (Mw) of 5100, a molecular weight dispersion (Mw / Mn) of 1.65, and a copolymerization composition ratio l / m of 40 / 60. Mn is the number-average molecular weight.

[0071] The porous polyamide films or porous polyimide films obtained in Examples 1-4 and Comparative Examples 1-3 were each cut into circles with a diameter of 47 mm and used as filters. After setting the filters in a perfluoroalkoxyalkane (PFA) filtration holder, 1000 mL of OK73 thinner was passed through the filters to wash them. The crude chemical solution described above was passed through the washed filters while pressurizing with nitrogen to a pressure of 0.08 MPa (G), and the purified chemical solution obtained by filtration was obtained as the filtrate.

[0072] [Measurement of Metal Atom Content] The metal compounds contained in the chemical solution samples filtered through the porous polyamide film or porous polyimide film obtained in Examples 1-4 and Comparative Examples 1-3 were heated at 600°C. After heating, the content of the metal compounds was determined from the mass of the remaining metal oxides. From the content of the metal compounds in the chemical solution samples, the content of metal atoms (mass ppb) relative to the total mass of the chemical solution purified by filtration was calculated. The metal atom content is shown in Table 1.

[0073] [Evaluation of Particle Quantity] For the purified chemical solutions filtered through the porous polyamide film or porous polyimide film obtained in Examples 1-4 and Comparative Examples 1-3, the number of particles larger than 0.135 μm was counted using a light scattering type liquid particle counter [manufactured by Rion Co., Ltd., model number: KS-41, light source: semiconductor laser-pumped solid-state laser (wavelength 830 nm, rated output 0.2 W), flow rate: 10 mL / min] based on the dynamic light scattering method. The counting was performed three times, and the average value was taken as the measured value. The above light scattering type liquid particle counter was calibrated with PSL (PolystyreneLatex) standard particle solution before use. The results are shown in Table 1 as "Particle Quantity".

[0074] [Evaluation of Defect Count] On a 12-inch silicon substrate treated with hexamethyldisilazane (HMDS), the chemical solution filtered through the porous polyamide film or porous polyimide film obtained in Examples 1-4 and Comparative Examples 1-3 was applied using a spinner. The silicon substrate with the formed coating film was pre-baked (PAB) on a hot plate at 80°C for 60 seconds to form a resin film with a thickness of 40 nm. The number of defects greater than 40 nm was measured on the obtained resin film using a surface defect observation device (KLA-Tencor, SurfScanSP5 instrument). The number of defects in the resin film formed using the chemical solution filtered through the porous polyamide film obtained in Examples 2, 3, 4 and Comparative Examples 1-3 was determined as a relative value, with the number of defects in the resin film formed using the chemical solution filtered through the porous polyamide film obtained in Example 1 set to 1. The number of defects is shown in Table 1.

[0075]

[0076] From the results shown in Table 1 above, it can be seen that when crude chemical solutions are filtered using the porous polyimide films of Examples 1 to 4, which have multiple spherical pores inside and in which multiple spherical pores are connected to adjacent spherical pores to form communicating pores, metal impurities and fine particles can be effectively removed.

Claims

1. A method for producing a purified chemical solution for use in the manufacture of semiconductor devices by purifying a crude chemical solution, comprising: filtering the crude chemical solution using a porous polyamide film as a filter; and recovering the liquid that has passed through the filter as the purified chemical solution, wherein the porous polyamide film has a plurality of spherical pores inside, and the plurality of spherical pores are connected to adjacent spherical pores to form communicating pores.

2. The method according to claim 1, wherein the amount of metal impurities contained in the purified chemical solution is less than the amount of metal impurities contained in the crude chemical solution.

3. The method according to claim 1, wherein the number of fine particles contained in the purified drug solution is less than the number of fine particles contained in the crude drug solution, and the number of fine particles is the number of particles with a diameter of 0.135 μm or more in 1 mL of sample, as measured using a light scattering type liquid particle size counter.

4. The method according to claim 1, wherein the purified chemical solution is a photosensitive resin composition that becomes poorly soluble in a developer upon exposure, or readily soluble in a developer upon exposure.

5. The method according to claim 4, wherein the photosensitive resin composition comprises an acid generator (A) that generates acid upon irradiation with active light or radiation, a resin (B) whose solubility in alkali increases due to the action of the acid, and an organic solvent (C).

6. The method according to claim 1, wherein the average pore diameter of the spherical pores is 10 nm or more and 200 nm or less.

7. Area of ​​the main surface of the porous polyamide film, 1 m² ２ The surface area of ​​the region is 1000 m ２ Over 6000m ２ The method according to claim 1, which is as follows.

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