KR-20260065847-A - Method for preparing an aqueous solution of a purified quaternary ammonium compound

KR20260065847AKR 20260065847 AKR20260065847 AKR 20260065847AKR-20260065847-A

Abstract

A method for preparing an aqueous solution of a quaternary ammonium compound is provided, wherein the aqueous solution of the quaternary ammonium compound has a molecular weight of 1000 g/mol or more, contains organic impurities of 1000 ppm or less, contains specific quaternary ammonium ions, and also contains metal impurities, wherein a crude aqueous solution of the quaternary ammonium compound containing metal impurities is brought into contact with a cation exchange resin having a degree of crosslinking of 6 or more and counter ions of a non-metallic ion type.

Inventors

이노우에 히로시
가와바타 유이치로

Assignees

가부시끼가이샤 도꾸야마

Dates

Publication Date: 20260511
Application Date: 20240830
Priority Date: 20230904

Claims (8)

As a method for preparing an aqueous solution of a quaternary ammonium compound, The aqueous solution of the quaternary ammonium compound contains organic impurities with a molecular weight of 1000 g/mol or more at a concentration of 1000 ppm or less, and contains quaternary ammonium ions represented by the following formula (1), and also contains a crude aqueous solution of the quaternary ammonium compound containing metal impurities. A method for preparing an aqueous solution of a purified quaternary ammonium compound, characterized by contacting it with a cation exchange resin having a crosslinking degree of 6 or higher and counter ions of the non-metallic ion type. (In the formula, R1 , R2 , R3 , and R4 are each independently an alkyl group having 1 to 16 carbon atoms, provided that among R1 , R2 , R3 , and R4 , one or more alkyl groups have 2 to 16 carbon atoms.)
In Article 1, A method for preparing a purified aqueous solution of a quaternary ammonium compound in which R1 , R2 , R3 , and R4 of the above formula (1) are not all the same alkyl group.
In Article 1, A method for preparing an aqueous solution of a purified quaternary ammonium compound, wherein among R1 , R2 , R3 , and R4 of the above formula (1), three are the same group and the remaining one is an alkyl group having 2 to 16 carbon atoms that is different from the group.
In any one of paragraphs 1 to 3, A method for preparing an aqueous solution of a purified quaternary ammonium compound, wherein the degree of crosslinking of the above cation exchange resin is 8 to 30.
In any one of paragraphs 1 to 4, A method for preparing an aqueous solution of a purified quaternary ammonium compound, wherein the above-mentioned cation exchange resin is composed of a strong acidic cation exchange resin.
In any one of paragraphs 1 to 5, A method for preparing a purified aqueous solution of a quaternary ammonium compound, wherein the contact of the cation exchange resin with the aqueous solution of the quaternary ammonium compound is carried out in a through-flow manner, and the cation exchange resin is applied to the aqueous solution of the quaternary ammonium compound at a through-flow rate of 2000 (L/L-resin) or more under conditions of a space velocity SV = 1 to 20 (1/hr).
In any one of paragraphs 1 to 6, A method for preparing a purified aqueous solution of a quaternary ammonium compound, wherein the above-mentioned cation exchange resin is obtained by contacting a cation exchange resin, in which the counter ion is of the hydrogen ion type, with an aqueous solution of a quaternary ammonium compound having the same quaternary ammonium ion as the above-mentioned crude aqueous solution of a quaternary ammonium compound.
In any one of paragraphs 1 to 7, A method for preparing a purified aqueous solution of a quaternary ammonium compound, wherein the crude aqueous solution of a quaternary ammonium compound is a crude aqueous solution of a quaternary ammonium hydroxide, a crude aqueous solution of a quaternary ammonium halogenated compound, or a crude aqueous solution of a quaternary ammonium carbonate.

Description

Method for preparing an aqueous solution of a purified quaternary ammonium compound The present invention relates to a method for preparing a purified aqueous solution of a quaternary ammonium compound, and more specifically, to a method for reducing the content of metal impurities from a crude aqueous solution of a quaternary ammonium compound containing metal impurities as impurities. Quaternary ammonium compounds are used as interphase transfer catalysts, surfactants, disinfectants, etc. In particular, quaternary ammonium hydroxide compounds, represented by tetramethylammonium hydroxide, are a type of organic alkali exhibiting strong basicity and are used as pH adjusters or in the form of aqueous solutions for cleaning, etching, and developing during semiconductor manufacturing. In these applications as semiconductor-related processing agents, as integration progresses, metal impurities can cause defects if they remain on the surface of electronic devices, so it is required to reduce them as much as possible. To be more specific, it is desired to reduce the content of metal impurities such as Na, K, Li, Ca, Mg, and Sr to 100 ppt or less when expressed as their total content. Generally, aqueous solutions of quaternary ammonium compounds are produced by synthesis methods using tertiary amines and alkyl salts, or by electrolytic decomposition methods using an electrolytic cell with an ion exchange membrane. For example, an aqueous solution of quaternary ammonium hydroxide is synthesized by using an aqueous solution of quaternary ammonium salt as a raw material and subjecting it to electrolysis, etc. In the aqueous solution of quaternary ammonium hydroxide synthesized in this way (or the aqueous solution of quaternary ammonium salt that is the raw material for obtaining it), the metal impurities are at a high content level of several hundred ppt or more, which is unsatisfactory from the perspective of the defect prevention effect in the semiconductor application. Filter treatment is a common method for purifying such crude aqueous ammonium compound solutions. However, while filter treatment provides an excellent reduction effect for particulate metal impurities, there was a problem in that, on the other hand, for dissociated ions, the removal effect was hardly exerted due to the limitations of the pore diameter. It is believed that adsorption treatment using a cation exchange resin is effective for the removal of metal ions from aqueous solutions of quaternary ammonium compounds. For example, Patent Document 1 describes that such treatment was performed on an aqueous solution of a quaternary ammonium hydroxide synthesized by the above electrolysis method, and that metal ions such as Na ions and Ca ions were each reduced to 1 ppb or less (see [0016] Reference Example 1, etc.). In addition, it is known that the adsorption treatment of a crude aqueous solution of a quaternary ammonium hydroxide compound (in the present invention, a crude aqueous solution of a quaternary ammonium hydroxide compound refers to an aqueous solution of a quaternary ammonium compound containing metal impurities and organic impurities with a molecular weight of 1000 g/mol or more and 1000 ppm or less) by a cation exchange resin is also applied for the purpose of recovering the quaternary ammonium hydroxide compound component from the waste liquid when the aqueous solution of the quaternary ammonium hydroxide compound is used as a photoresist developer for semiconductor manufacturing (e.g., Patent Document 2, etc.). Here, the strong acidic cation exchange resin product used in Example 1, which is presented as a representative example of a cation exchange resin in the above Patent Document 2, is described as having a degree of crosslinking of 2 to 10% by referring to Patent Document 3 (bottom right column of page 3). Figure 1 is a schematic diagram of an electrolytic cell used for the production of quaternary ammonium compounds. In the present invention, the crude aqueous solution of a quaternary ammonium compound, which is the liquid to be treated and contacted with a cation exchange resin, has a purity level of 1,000 ppm or less of organic impurities with a molecular weight of 1,000 g/mol or more. The above impurities are introduced from the raw materials used in the synthesis of the quaternary ammonium compound, as well as from reaction vessels, piping, and contact members of the vessels. By using high-purity raw materials and appropriately selecting contact members, it is possible to obtain an aqueous solution of a quaternary ammonium compound that satisfies the requirements for the purity of the above organic impurities. On the other hand, even with the same aqueous solution of a quaternary ammonium compound, if it becomes waste liquid of photoresist developer discharged during semiconductor manufacturing, the requirements regarding the purity of the above organic impurities are not satisfied because it contains various organic impu