Methods for manufacturing organic solvents

Abstract

This invention provides a method for manufacturing an organic solvent that reduces metal impurities, which are a cause of minute defects on wafers, during the lithography process in semiconductor device manufacturing, or a method for reducing metal impurities in purified organic solvents. This invention is a method for manufacturing an organic solvent that includes a step of passing liquid through a filter element. The filter element is characterized by laminating or winding a plurality of different types of filter base fabrics into a hollow inner cylinder. The filter base fabric is a nonwoven fabric with chemically bonded metal adsorption groups to polyolefin fibers. The filter base fabric includes a nonwoven layer A and a nonwoven layer B. The nonwoven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The nonwoven layer B is composed of polyolefin fibers with at least one group selected from the group consisting of amino groups, N-methyl-D-glucosamine groups, iminodiacetic acid groups, iminodiethanol groups, acetobenzoic acid oxime groups, phosphate groups, carboxylic acid groups, and ethylenediaminetriacetic acid groups as metal adsorption groups.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an organic solvent that reduces metallic impurities that cause defects in the lithography process of semiconductor device manufacturing. Prior Technology

[0002] Organic solvents used in the lithography process of semiconductor device manufacturing aim to reduce metallic impurities that contribute to minute defects (e.g., around 1-100 nm, referred to as defects) on wafers. Patent Document 1 discloses a filter with high efficiency in adsorbing and removing metals. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-167223 Summary of the Invention

[0004] [The problem the invention aims to solve] The present invention provides a method for manufacturing an organic solvent that reduces metal impurities that cause minute defects on wafers during the lithography process in semiconductor device manufacturing, and a method for reducing the metal content of the organic solvent. [Methods used to solve problems]

[0005] The present invention includes the following. [1] A method for manufacturing an organic solvent, comprising the step of passing liquid through a filter element for metal removal, wherein the filter element for metal removal is characterized by laminating or winding a plurality of different types of filter base fabrics into a filter element with a hollow inner cylinder. The aforementioned filter base fabric is a nonwoven fabric composed of polyolefin fibers chemically bonded to metal adsorption groups. The aforementioned filter base fabric includes non-woven layer A and non-woven layer B. The aforementioned nonwoven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The aforementioned nonwoven layer B is composed of polyolefin fibers with at least one of the following groups as metal adsorption groups: amine, N-methyl-D-glucosamine, iminodiacetic acid, iminodiethanol, acetylaminooxime, phosphate, carboxylic acid and ethylenediaminetriacetic acid. [2] The method for manufacturing organic solvents as described in [1] further includes the step of passing liquid through a filter cartridge for microparticle removal. [3] The method for manufacturing organic solvents as described in [2], wherein the material of the filter for removing microparticles is selected from at least one of polyethylene and nylon. [4] The method for manufacturing an organic solvent as described in any of [1] to [3], wherein the organic solvent is an organic solvent used as an inhibitor underlayer film. [5] The method for manufacturing an organic solvent as described in [4], wherein the organic solvent is at least one selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, γ-butyrolactone, ethyl lactate, butyl lactate and cyclohexanone. [6] A method for reducing metals in a purified organic solvent, wherein the purified organic solvent is passed through a metal removal filter cartridge to reduce metals, wherein the filter cartridge is characterized by laminating or winding multiple types of filter base fabrics in a hollow inner cylinder. The aforementioned filter base fabric is a nonwoven fabric composed of polyolefin fibers chemically bonded to metal adsorption groups. The aforementioned filter base fabric includes non-woven layer A and non-woven layer B. The aforementioned nonwoven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The aforementioned nonwoven layer B is composed of polyolefin fibers with at least one of the following groups as metal adsorption groups: amine, N-methyl-D-glucosamine, iminodiacetic acid, iminodiethanol, acetylaminooxime, phosphate, carboxylic acid and ethylenediaminetriacetic acid. [Invention Effects]

[0006] By using the filter element described in this invention to manufacture organic solvents, it is possible to produce organic solvents with significantly reduced metallic impurities. By using this organic solvent, various minute defects (flaws) in the lithography step of semiconductor manufacturing can be reduced. Implementation

[0007] <Methods for manufacturing organic solvents> The method for manufacturing the organic solvent of the present invention includes the step of passing a purified organic solvent, which is in solution at room temperature, through a metal removal filter element as detailed below.

[0008] The above-described liquid-passing step can be performed using, for example, a commercially available organic solvent to be purified, via a metal removal filter cartridge directly connected (at both the inlet and outlet) to the manufacturing equipment (manufacturing container) using the organic solvent. The liquid-passing step can be performed once or more. Preferably, the liquid-passing step is a circulating filtration using a pump. More preferably, in addition to the metal removal filter cartridge of this invention, the organic solvent is circulated through both sides of a particle removal filter cartridge connected in a straight line. The circulation time is, for example, 3 to 144 hours. The filtration flow rate is, for example, 1 to 1000 L / hour.

[0009] <Purified organic solvent> While the purified organic solvents used in this case are recommended, such as those commonly used in the lithography steps described below, they are not limited to these.

[0010] Examples of the aforementioned purified organic solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, 4-methyl-2-pentanol, and 2-hydroxyisocyanate. Methyl butyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxylate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents can be used alone or in combination of two or more.

[0011] Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, γ-butyrolactone, ethyl lactate, butyl lactate, and cyclohexanone are preferred. Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether are particularly preferred.

[0012] <Filter Cartridge> As for the filter element in this case, the one described in Japanese Patent Application Publication No. 2018-167223 is preferred.

[0013] The filter element of the present invention is a filter element in which multiple types of filter base fabrics are laminated or wound in a hollow inner cylinder. The filter base fabric is characterized in that the aforementioned filter base fabric is a non-woven fabric with chemically bonded metal adsorption groups to polyolefin fibers. The aforementioned filter base fabric includes a non-woven layer A and a non-woven layer B. The aforementioned non-woven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The aforementioned non-woven layer B is composed of polyolefin fibers with at least one of the following groups as metal adsorption groups: amino groups, N-methyl-D-glucosamine groups, iminodiacetic acid groups, iminodiethanol groups, acetaminophen groups, phosphate groups, carboxylic acid groups, and ethylenediaminetriacetic acid groups.

[0014] This invention relates to a filter cartridge in which multiple types of filter base fabrics are laminated or wound into a hollow inner cylinder. The filter base fabric is a nonwoven fabric with chemically bonded metal adsorption groups made of polyolefin fibers. The filter base fabric comprises nonwoven layer A and nonwoven layer B. Furthermore, nonwoven layer A is composed of polyolefin fibers with chemically bonded metal adsorption groups, and nonwoven layer B is composed of polyolefin fibers with metal adsorption groups selected from at least one group selected from the group consisting of amine, N-methyl-D-glucosamine, iminodiacetic acid, iminodiethanol, acetyl oxime, phosphate, carboxylic acid, and ethylenediaminetriacetic acid. This allows for efficient and effective removal of metals. Additionally, a filter base fabric combining different types of filter base fabrics to form a single filter base fabric is also included in the multiple types of filter base fabrics.

[0015] In this invention, the nonwoven layer B is preferably composed of polyolefin fibers with chemically bonded imino diethanol groups. This is because it has high metal removal efficiency. For adsorbable metals, the sulfonic acid groups mainly adsorb Na, Cu, and K, while the imino diethanol groups mainly adsorb Cr, Al, and Fe.

[0016] The polyolefin fibers constituting nonwoven fabrics A and B are preferably long fibers. This is because long-fiber nonwoven fabrics are less prone to fiber lint and have higher filter performance. More preferably, they are meltblown long-fiber nonwoven fabrics with a mass per unit area (weight per unit area) of 10~100 g / m².

[0017] The average diameter of the single polyolefin fibers constituting the aforementioned nonwoven fabrics A and B is preferably 0.2~10 μm. Within this range, high filter performance is expected. Furthermore, since the surface area (specific surface area) can be increased, the surface area of ​​the substrate for the grafting polymerization reaction is also increased, thus improving the grafting rate is also expected.

[0018] The polyolefin fiber is preferably selected from at least one of the group consisting of polypropylene, copolymers of propylene and ethylene, polyethylene, and copolymers of ethylene with other α-olefins having 4 or more carbon atoms, with high-density polyethylene being particularly preferred. These polymers are inert, stable to pharmaceutical solutions, and can be graft-polymerized.

[0019] The aforementioned filter element is preferably a filter element comprising a hollow inner cylinder and a filter base cloth. The aforementioned filter base cloth is a non-woven fabric with chemically bonded metal adsorption groups on polyolefin fibers. The aforementioned filter base cloth is formed by winding the aforementioned hollow inner cylinder to form a laminated structure of the filter element.

[0020] The filter of this invention is a filter in which the aforementioned filter element is assembled. For example, the filter element is a filter base cloth wound around an inner cylinder and housed in a container. When assembling the filter element into the filter container, for example, the filter element is assembled into the filter with the container housing it. Furthermore, in the case of a cartridge-type filter, the filter function can be regenerated by simply replacing the filter element. The case of a capsule-type filter, where the container for each filter is replaced, is also included in this invention. In the case of a capsule-type filter, the portion corresponding to the filter element becomes the filtration section.

[0021] Next, methods for chemically bonding various functional groups to polyolefin fibers are explained. Examples of such methods include irradiating polyolefin fibers with electron beams, gamma rays, or similar radiation, followed by contacting the fibers with a latex solution containing reactive monomers such as GMA; and irradiating polyolefin fibers with a latex solution containing reactive monomers, followed by irradiation with electron beams, gamma rays, or similar radiation, and then grafting and polymerizing the reactive monomers onto the polyolefin fibers. When irradiating with an electron beam, an irradiation dose of 1-200 kGy is typically achieved, preferably 5-100 kGy, and more preferably 10-50 kGy. Irradiation is preferably performed in a nitrogen environment. Commercially available electron beam irradiation devices can be used, such as the EC250 / 15 / 180L (manufactured by Iwasaki Electric Co., Ltd.), EC300 / 165 / 800 (manufactured by Iwasaki Electric Co., Ltd.), and EPS300 (manufactured by NHC Corporation), etc., as area beam type electron beam irradiation devices.

[0022] Specifically, as an example of the aforementioned graft polymerization method, liquid-phase graft polymerization can be used. This involves activating the nonwoven fabric by irradiation with gamma rays or electron beams, then impregnating it with a latex containing water, surfactants, and reactive monomers, and completing graft polymerization on the aforementioned nonwoven fabric substrate. Next, functional groups such as sulfonic acid groups, amino groups, N-methyl-D-glucosamine groups, or iminodiacetic acid groups (iminodiacetic acid groups), iminodiethanol groups, acetaminophen groups, phosphate groups, carboxylic acid groups, and ethylenediaminetriacetic acid groups, i.e., ion exchange groups and / or chelating groups, are introduced into the graft chains formed on the aforementioned substrate. In this invention, the method is not limited to liquid-phase graft polymerization; gas-phase graft polymerization, where monomer vapor contacts the substrate for polymerization, and impregnation gas-phase graft polymerization, where the substrate is impregnated in a monomer solution, removed from the monomer solution, and reacted in the gas phase, are also applicable. The chemical formulas of the representative functional groups are as follows: (Chemical 1) represents sulfonic acid group (SC group), (Chemical 2) represents iminodiethanol group (IDE group), (Chemical 3) represents iminodiacetic acid group (IDA group), and (Chemical 4) represents N-methyl-D-glucosamine group (NMDG group).

[0023]

[0024]

[0025]

[0026]

[0027] However, in (Chemical 1) to (Chemical 3), R is either polyethylene (PE) + GMA (Chemical 5) or polypropylene (PP) + GMA (Chemical 6). In (Chemical 4), R is methyl.

[0028]

[0029]

[0030] However, in the aforementioned (Transformation 5) to (Transformation 6), n and m are integers greater than or equal to 1.

[0031] <Filter for microparticle removal> The preferred method for manufacturing the organic solvent of the present invention involves passing the purified organic solvent through the filter element and then through a microparticle removal filter. The microparticle removal filter may be any material known herein. The material of the microparticle removal filter is preferably selected from at least one material formed of polyethylene and nylon.

[0032] The pore size of filters for removing microparticles is typically below 30 nm, preferably, for example, 0.1 nm to 30 nm, for example, 0.1 nm to 20 nm, or for example, 1 nm to 10 nm.

[0033] <Metal Reduction Methods> The metal reduction method in this case is a method for reducing the metal content of a purified organic solvent. It involves passing the purified organic solvent through a metal removal filter cartridge to reduce the metal content. The filter cartridge is characterized by having multiple types of filter base fabric laminated or wound into a hollow inner cylinder. The aforementioned filter base fabric is a nonwoven fabric composed of polyolefin fibers chemically bonded to metal adsorption groups. The aforementioned filter base fabric includes non-woven layer A and non-woven layer B. The aforementioned nonwoven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The aforementioned nonwoven layer B is composed of polyolefin fibers with at least one of the following groups as metal adsorption groups: amine, N-methyl-D-glucosamine, iminodiacetic acid, iminodiethanol, acetylaminooxime, phosphate, carboxylic acid and ethylenediaminetriacetic acid.

[0034] This step reduces metallic impurities originating from the raw materials or solvents contained in the purified organic solvent, and also reduces defects in the lithography process. Various metallic impurities (such as Na, Cu, Cr, Al, Fe, etc.) can be reduced to, for example, below 0.5 ppb or below 0.4 ppb using the aforementioned metal reduction methods. The above-mentioned metal impurity content was determined by, for example, the method described in the embodiments. [Example]

[0035] Although the present invention will be described in more detail below with reference to embodiments and the like, the present invention is not limited by the embodiments and the like.

[0036] <Example 1> As the purified organic solvent, 20L of propylene glycol monomethyl ether (PM-P: manufactured by KH Neochem Co., Ltd.) was filtered for 100 minutes using a 10-inch cartridge filter (manufactured by Kurashiki Fiber Processing Co., Ltd.) as described in Japanese Patent Application Publication No. 2018-167223 at a flow rate of 3L per minute. The metal content of the filtered organic solvent was determined by ICP-MS (Agilent 8800: manufactured by Agilent Technologies Co., Ltd.).

[0037] <Comparative Example 1> The purified organic solvent used in Example 1 was not filtered; instead, the metal content was determined using the same method.

[0038] <Comparative Example 2> Except for changing the filter cartridge of Example 1 to a filter cartridge filter (Nylon filter ABD1ANM3EH1 (20nm Nylon filter): manufactured by Pall Co., Ltd., Japan), the filtration was carried out in the same way as in Example 1, and the metal content was determined in the same way.

[0039] <Comparative Example 3> Except for replacing the filter cartridge of Example 1 with 20 kg of strong acid ion exchange resin (XSC-1115-H: manufactured by Muromachi Chemicals Co., Ltd.) and performing ion exchange for 4 hours, the filtration was carried out in the same manner as in Example 1, and the metal content was determined in the same manner.

[0040] <Metal Concentration in Organic Solvents> The results of measuring the metal concentration after implementing the treatment method of Example 1 are shown in Table 1.

[0041]

[0042] As shown in Table 1, Example 1 effectively reduced the metal concentration.

[0043] <Example 2> As the purified organic solvent, 20L of propylene glycol monomethyl ether acetate (EL-PGMEA: manufactured by Toyo Gosei Kogyo Co., Ltd.) was filtered for 50 minutes using a 10-inch cartridge filter (manufactured by Kurashiki Fiber Processing Co., Ltd.) as described in Japanese Patent Application Publication No. 2018-167223 at a flow rate of 2L per minute. The metal content of the filtered organic solvent was determined by ICP-MS (Agilent 8800: manufactured by Agilent Technologies Co., Ltd.).

[0044] <Comparative Example 4> The purified organic solvent used in Example 1 was not filtered; instead, the metal content was determined using the same method.

[0045]

[0046] As shown in Table 2, Example 2 effectively reduced the metal concentration. [Industrial Applicability]

[0047] According to the present invention, an organic solvent can be provided that particularly reduces the amount of metal impurities.

Claims

1. A method for manufacturing an organic solvent, comprising the step of passing a liquid through a metal removal filter cartridge, wherein the organic solvent is an organic solvent used as an inhibitor in the formation of a lower membrane, and the organic solvent is at least one selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, γ-butyrolactone, ethyl lactate, butyl lactate, and cyclohexanone; the metal removal filter cartridge is characterized by having a plurality of filter base fabrics laminated or wound in a hollow inner cylinder; the filter base fabric is a nonwoven fabric of polyolefin fibers with chemically bonded metal adsorption groups; the filter base fabric comprises a nonwoven layer A and a nonwoven layer B; the nonwoven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The aforementioned nonwoven layer B is composed of polyolefin fibers with at least one of the following groups as metal adsorption groups: amine, N-methyl-D-glucosamine, iminodiacetic acid, iminodiethanol, acetylaminooxime, phosphate, carboxylic acid and ethylenediaminetriacetic acid.

2. The method for manufacturing an organic solvent as described in claim 1, which further includes the step of passing liquid through a filter element for microparticle removal.

3. The method for manufacturing the organic solvent as described in claim 2, wherein, The material of the above-mentioned microparticle removal filter is selected from at least one of polyethylene and nylon.

4. A method for reducing metals in a purified organic solvent, comprising passing the purified organic solvent through a metal removal filter cartridge to reduce metals, wherein the organic solvent is an organic solvent used as an inhibitor in the formation of a lower membrane, and the organic solvent is at least one selected from the group consisting of propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, γ-butyrolactone, ethyl lactate, butyl lactate, and cyclohexanone; the filter cartridge is characterized by laminating or winding a plurality of filter base fabrics into a hollow inner cylinder; the filter base fabric is a nonwoven fabric of polyolefin fibers with chemically bonded metal adsorption groups; the filter base fabric comprises a nonwoven layer A and a nonwoven layer B; the nonwoven layer A is composed of polyolefin fibers with chemically bonded sulfonic acid groups as metal adsorption groups. The aforementioned nonwoven layer B is composed of polyolefin fibers with at least one of the following groups as metal adsorption groups: amine, N-methyl-D-glucosamine, iminodiacetic acid, iminodiethanol, acetylaminooxime, phosphate, carboxylic acid and ethylenediaminetriacetic acid.