Preparation method of high-purity trihydroxyethyl methyl ammonium hydroxide and prepared high-purity quaternary ammonium base

Abstract

The invention discloses a preparation method of high-purity trihydroxyethyl methyl ammonium hydroxide and high-purity quaternary ammonium base prepared by the preparation method, and relates to the technical field of high-purity quaternary ammonium base production. The preparation method of the high-purity tris (2-hydroxyethyl) methyl ammonium hydroxide comprises the following steps: electrolysis: taking tris (2-hydroxyethyl) methyl quaternary ammonium salt, and preparing into an aqueous solution; the method comprises the following steps: adding trihydroxyethyl methylammonium chloride into a raw material chamber of an electrolytic bath, and electrolyzing, so that trihydroxyethyl methylammonium cations enter a cathode chamber through a cation membrane and are combined with hydroxyl ions generated by a cathode to form trihydroxyethyl methylammonium hydroxide, thereby obtaining the quaternary ammonium base. The preparation method of the high-purity trihydroxyethyl methyl ammonium hydroxide has the advantage of being beneficial to improving the quality of a quaternary ammonium base product.

Description

Technical Field

[0001] This application relates to the field of hydroxyalkyl-containing organic quaternary ammonium base production technology, and in particular to a method for preparing high-purity trihydroxyethylmethylammonium hydroxide and the high-purity quaternary ammonium base prepared therefrom. Background Technology

[0002] In the semiconductor manufacturing industry, chemical mechanical polishing (CMP) of semiconductor wafers often leaves contaminants on the wafer surface, requiring the use of cleaning agents to clean the wafer surface. Tetramethylammonium hydroxide (TMAH) is highly alkaline and can effectively remove contaminants without leaving any residue after cleaning. It performs excellently in the cleaning process of electronic products such as PCBs and is suitable for wafer cleaning in semiconductor manufacturing.

[0003] However, tetramethylammonium hydroxide is prone to decomposition during use, forming toxic trimethylamine, which poses a certain degree of environmental harm. There is a need to find a quaternary ammonium base semiconductor chip cleaning agent that can replace tetramethylammonium hydroxide. Among them, triethylmethylammonium hydroxide is gradually being used in the chip cleaning field due to its excellent cleaning effect and suitable etching rate for wafers. Triethylmethylammonium hydroxide is also used in the field of semiconductor developing solutions due to its excellent thermal stability.

[0004] Chinese patent application number 01822782.1 discloses a semiconductor developer solution using methyldiethanolamine, ethylene oxide, and water as raw materials to prepare tris(2-hydroxyethyl)methylammonium hydroxide. However, this patent uses flammable and explosive ethylene oxide, which has a wide explosion limit range, resulting in poor safety performance of the process. Furthermore, the reaction is incomplete, and ethylene oxide is easily hydrolyzed, leaving behind impurities such as methyldiethanolamine and ethylene glycol, which negatively impact the quality of the tris(2-hydroxyethyl)methylammonium hydroxide. Summary of the Invention

[0005] To improve the quality of trihydroxyethylmethylammonium hydroxide, this application provides a method for preparing high-purity trihydroxyethylmethylammonium hydroxide and the high-purity quaternary ammonium base prepared therefrom.

[0006] In a first aspect, this application provides a method for preparing high-purity trihydroxyethylmethylammonium hydroxide, employing the following technical solution: A method for preparing high-purity trihydroxyethylmethylammonium hydroxide includes the following steps: electrolysis: trihydroxyethylmethyl quaternary ammonium salt is prepared into an aqueous solution; it is added to the raw material chamber of an electrolytic cell; through electrolysis, the trihydroxyethylmethylammonium cation passes through the cation membrane into the cathode chamber, combines with the hydroxide ions generated at the cathode to form trihydroxyethylmethylammonium hydroxide, and thus a quaternary ammonium base is obtained.

[0007] The conventional method for preparing tri(2-hydroxyethyl)methylammonium hydroxide uses methyl diethanolamine, ethylene oxide, and water as raw materials. However, this method uses flammable and explosive ethylene oxide, which has a wide explosion limit, resulting in poor process safety. Furthermore, the reaction is incomplete, and ethylene oxide is easily hydrolyzed, leaving behind impurities such as methyl diethanolamine and ethylene glycol, which negatively impact the quality of the tri(2-hydroxyethyl)methylammonium hydroxide. By adopting the above-mentioned technical solution, using tri(2-hydroxyethyl)methyl quaternary ammonium salt as a raw material and preparing tri(2-hydroxyethyl)methylammonium hydroxide via electrolysis, the use of flammable and explosive ethylene oxide is avoided, improving the process safety. The absence of methyl diethanolamine as a raw material helps avoid residual methyl diethanolamine in the product, and the absence of ethylene oxide as a raw material helps avoid residual ethylene oxide hydrolysis products, thus contributing to improved product quality of tri(2-hydroxyethyl)methylammonium hydroxide.

[0008] Preferably, the trihydroxyethylmethyl quaternary ammonium salt is trihydroxyethylmethyl ammonium chloride, trihydroxyethylmethyl ammonium bromide, or trihydroxyethylmethyl ammonium bicarbonate.

[0009] By adopting the above technical solution, this application can prepare trihydroxyethylmethyl ammonium hydroxide using different trihydroxyethylmethyl quaternary ammonium salts as raw materials, which is beneficial to improving the applicability of the preparation method of trihydroxyethylmethyl ammonium hydroxide.

[0010] Preferably, the trihydroxyethylmethyl quaternary ammonium salt is trihydroxyethylmethyl ammonium chloride.

[0011] By adopting the above technical solution, using trihydroxyethylmethylammonium chloride as a raw material, the use of bromides is avoided, which helps to reduce production costs.

[0012] Preferably, the cathode of the electrolytic cell uses a platinum electrode plate.

[0013] Nickel cathodes are commonly used in electrolysis processes. Triethylmethylammonium hydroxide (TMA) molecules contain three hydroxyl groups, which readily complex with nickel ions, resulting in a high nickel ion content in the product. Using platinum cathodes helps prevent the hydroxyl groups in the TMA molecule from complexing with nickel and other metal ions, thus reducing the metal ion content and improving product quality. Furthermore, TMA is prone to oxidation and decomposition, tending to result in a darker color. Using platinum cathodes helps reduce the probability of oxidation and decomposition, lowering the color grade and further improving product quality.

[0014] Preferably, the electrolytic cell includes an anode chamber (1), a raw material chamber (2), and a cathode chamber (3) that are sequentially adjacent to each other; an anode plate (4) is installed in the anode chamber (1), and a cathode plate (5) is installed in the cathode chamber (3); the anode plate (4) and the cathode plate (5) are connected by a power source; the anode chamber (1) and the raw material chamber (2) are connected by an anion exchange membrane (6), and the raw material chamber (2) and the cathode chamber (3) are connected by a cation exchange membrane (7).

[0015] By adopting the above technical solution and using the three-chamber two-membrane method for electrolysis, the trihydroxyethylmethyl quaternary ammonium cation enters the cathode chamber through the cation membrane and combines with the hydroxide ions generated in the cathode chamber to form trihydroxyethylmethyl ammonium hydroxide. This helps to avoid impurities such as tertiary amines remaining in the trihydroxyethylmethyl quaternary ammonium salt from entering the product, thus helping to improve product quality.

[0016] Preferably, the mass concentration of trihydroxyethylmethyl quaternary ammonium salt in the raw material chamber is 12.5-15%.

[0017] By adopting the above technical solution, the concentration of trihydroxyethyl methyl quaternary ammonium salt in the raw material chamber needs to be moderate. Too high or too low concentrations will affect product quality. Controlling the concentration of trihydroxyethyl methyl quaternary ammonium salt in the raw material chamber helps to improve product quality.

[0018] A high-purity quaternary ammonium base is prepared by the above-described method for preparing high-purity trihydroxyethylmethylammonium hydroxide.

[0019] By adopting the above technical solution and using the method disclosed in this application to prepare trihydroxyethylmethylammonium hydroxide, the impurity content is low and the product purity is high.

[0020] In summary, this application includes at least one of the following beneficial technical effects: This application uses trihydroxyethylmethyl quaternary ammonium salt as raw material to prepare trihydroxyethylmethyl ammonium hydroxide by electrolysis, which avoids the use of flammable and explosive ethylene oxide, thus helping to improve the safety of the production process; it avoids the use of methyldiethanolamine, thus helping to avoid residual methyldiethanolamine in the product, thus helping to improve product quality; and it avoids the use of ethylene oxide, which is prone to hydrolysis, thus helping to reduce impurities and improve product quality. In the electrolysis process of trihydroxyethylmethyl quaternary ammonium salt, this application uses a platinum electrode as the cathode, which helps to reduce the content of metal ions such as nickel, improves the color of the product, and enhances the product quality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the electrolytic cell structure used in this application.

[0022] Reference numerals: 1. Anode chamber; 2. Raw material chamber; 3. Cathode chamber; 4. Anode plate; 5. Cathode plate; 6. Anion exchange membrane; 7. Cation exchange membrane. Detailed Implementation

[0023] In this application, trihydroxyethylmethylammonium hydroxide is tri(2-hydroxyethyl)methylammonium hydroxide; and trihydroxyethylmethyl quaternary ammonium salt is tri(2-hydroxyethyl)methyl quaternary ammonium salt.

[0024] The conventional synthesis process for tri(2-hydroxyethyl)methylammonium hydroxide uses methyldiethanolamine, ethylene oxide, and water as raw materials. This conventional method uses flammable and explosive ethylene oxide, which has a wide explosion limit range and poor safety performance. Furthermore, the reaction is incomplete, and ethylene oxide is easily hydrolyzed, leaving behind impurities such as methyldiethanolamine and ethylene glycol, which negatively impact the quality of the tri(2-hydroxyethyl)methylammonium hydroxide.

[0025] During the preparation of trihydroxyethylmethylammonium hydroxide by electrolysis, nickel metal ions in the nickel electrode plate easily complex with the hydroxyl groups in the trihydroxyethylmethylammonium hydroxide molecule, resulting in a higher metal ion concentration; and trihydroxyethylmethylammonium hydroxide is prone to oxidation and decomposition reactions, resulting in a higher color number.

[0026] Based on the aforementioned technical background, this application proposes a technical solution to prepare trihydroxyethylmethyl ammonium hydroxide by electrolysis using trihydroxyethylmethyl quaternary ammonium salt as a raw material. This helps reduce the content of impurities such as methyldiethanolamine and ethylene glycol in the product, thereby improving product quality and enhancing the safety of the production process. The inventors discovered through extensive experimentation that using a platinum electrode as the cathode can reduce the metal ion content and color grade of the product, thus contributing to improved product quality.

[0027] The specific implementation method is described below.

[0028] The water used in the following examples is deionized water with a conductivity not exceeding 20 μS / cm. The power supply for the electrolysis process is a DC power supply. During electrolysis, the mass concentration of triethylmethylammonium chloride in the feed chamber is not greater than 15%, preferably 12.5-15%. During electrolysis, the chloride ion concentration in the feed chamber is titrated with silver nitrate, and the triethylmethylammonium chloride concentration is calculated and monitored. Based on the changes in the triethylmethylammonium chloride concentration in the feed chamber, an aqueous solution of triethylmethylammonium chloride is added to the feed chamber during electrolysis to maintain the mass concentration of triethylmethylammonium chloride in the feed chamber at 12.5-15%. Metal ions are detected using ICP-MS, and color numbers are detected using a colorimetric method.

[0029] The following examples use the same electrolysis equipment. Before starting electrolysis, the electrolyzer is filled with water.

[0030] The present application will be further described in detail below with reference to the accompanying drawings. Example

[0031] Example 1: A method for preparing high-purity trihydroxyethylmethylammonium hydroxide, comprising the following steps: Electrolysis: Take 15 kg of triethylmethylammonium chloride and add pure water to prepare a 40% (w / w) aqueous solution of triethylmethylammonium chloride. Add the triethylmethylammonium chloride aqueous solution to the raw material chamber 2 of the electrolytic cell, and dilute with water until the mass concentration of triethylmethylammonium chloride in the raw material chamber 2 is 14%. The electrolytic cell includes an anode chamber 1, a raw material chamber 2, and a cathode chamber 3, which are connected in sequence. An anode plate 4 is installed in the anode chamber 1, and a cathode plate 5 is installed in the cathode chamber 3. The cathode plate 5 is a nickel electrode plate, and the anode plate 4 and the cathode plate 5 are connected by a power source. The anode chamber 1 and the raw material chamber 2 are connected by an anion exchange membrane 6, and the raw material chamber 2 and the cathode chamber 3 are connected by a cation exchange membrane 7. Water is added to the anode chamber 1 and the cathode chamber 3 during electrolysis. First, the triethylmethylammonium chloride aqueous solution is added to the raw material chamber 2. Through electrolysis, the triethylmethylammonium cations pass through the cation exchange membrane 7 into the cathode chamber 3 and combine with the hydroxide ions generated at the cathode to form triethylmethylammonium hydroxide.

[0032] During electrolysis, the materials in anode chamber 1, raw material chamber 2, and cathode chamber 3 are circulated using separate circulation pumps. The circulation flow rate in anode chamber 1 and cathode chamber 3 is 80 ml / min, while the circulation flow rate in raw material chamber 2 is 150 ml / min. Based on the concentration changes of triethylmethylammonium chloride in raw material chamber 2, an aqueous solution of triethylmethylammonium chloride is added to raw material chamber 2 during electrolysis to maintain its concentration at 12.5-15%. After 36 hours of electrolysis, the concentration of triethylmethylammonium hydroxide in cathode chamber 3 increases to approximately 35%. Water is then added to cathode chamber 3 to maintain the concentration at approximately 35%. Product is discharged from cathode chamber 3 every 12 hours to maintain the liquid level at a suitable position. Electrolysis is continued for 120 hours, and the metal ion content, color number, and other indicators of the product generated after 120 hours of electrolysis are measured. Example

[0033] The difference between Example 2 and Example 1 is that in Example 2, trihydroxyethylmethylammonium bromide is used instead of trihydroxyethylmethylammonium chloride as the electrolytic raw material, while all other aspects are the same as in Example 1. Example

[0034] The difference between Example 3 and Example 1 is that the cathode plate in Example 3 is a platinum cathode plate, while all other aspects are the same as in Example 1.

[0035] Comparative Example 1 Comparative Example 1, referring to the technical solution in Example 2 of Chinese Patent 01822782.1, used methyl diethylene glycol, ethylene oxide, and water as raw materials, reacting them for 24 hours in a molar ratio of methyl diethylene glycol: ethylene oxide: water of 1:1:10 to prepare trihydroxyethylmethylammonium hydroxide. The mass content of trihydroxyethylmethylammonium hydroxide in the product was determined to be 50.14%, and the mass content of methyl diethylene glycol was 2.37%.

[0036] Table 1 Comparison of Metal Ion Content in Products After 120h of Electrolysis Table of Comparison of Metal Ion Content in Products Comparative Example 1 used methyl diethylene glycol, ethylene oxide, and water as raw materials to prepare trihydroxyethylmethylammonium hydroxide. The product contained a high residual amount of methyl diethanolamine and also contained ethylene oxide hydrolysis byproducts, resulting in numerous impurities and low product quality. Furthermore, the use of flammable and explosive ethylene oxide raised concerns about the safety of this preparation method.

[0037] Comparing the experimental results of Example 1 and Comparative Example 1, Example 1 uses trihydroxyethylmethylammonium chloride as raw material to prepare trihydroxyethylmethylammonium hydroxide by electrolysis. It does not use methyldiethanolamine and ethylene oxide, which has better safety, helps to reduce the impurity content in the product, and helps to improve the product quality.

[0038] Comparing the experimental results of Example 1 and Example 2, Example 2 used trihydroxyethylmethylammonium bromide as raw material to prepare trihydroxyethylmethylammonium hydroxide by electrolysis. The metal ion content and color number were not much different from those of Example 1, and the product quality was similar.

[0039] Comparing the experimental results of Example 1 and Example 3, Example 3 used a platinum electrode plate instead of a nickel electrode plate as the cathode plate, which significantly reduced the nickel ion content and platinum ion content of the product, and also significantly reduced the color number, which is beneficial to improving product quality.

[0040] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing high-purity trihydroxyethylmethylammonium hydroxide, characterized in that, Includes the following steps: Electrolysis: Trihydroxyethyl methyl quaternary ammonium salt is prepared into an aqueous solution and added to the raw material chamber of the electrolytic cell. Through electrolysis, the trihydroxyethyl methyl ammonium cations pass through the cation membrane into the cathode chamber and combine with the hydroxide ions generated at the cathode to form trihydroxyethyl methyl ammonium hydroxide, thus producing a quaternary ammonium base.

2. The method for preparing high-purity trihydroxyethylmethylammonium hydroxide according to claim 1, characterized in that: The trihydroxyethylmethyl quaternary ammonium salt is trihydroxyethylmethyl ammonium chloride, trihydroxyethylmethyl ammonium bromide, or trihydroxyethylmethyl ammonium bicarbonate.

3. The method for preparing high-purity trihydroxyethylmethylammonium hydroxide according to claim 2, characterized in that: The trihydroxyethylmethyl quaternary ammonium salt is trihydroxyethylmethyl ammonium chloride.

4. The method for preparing high-purity trihydroxyethylmethylammonium hydroxide according to claim 1, characterized in that: The cathode of the electrolytic cell uses a platinum electrode plate.

5. The method for preparing high-purity trihydroxyethylmethylammonium hydroxide according to claim 1, characterized in that: The electrolytic cell includes an anode chamber (1), a raw material chamber (2), and a cathode chamber (3) that are adjacent to each other in sequence; an anode plate (4) is installed in the anode chamber (1), and a cathode plate (5) is installed in the cathode chamber (3). The anode plate (4) and the cathode plate (5) are connected by a power source; the anode chamber (1) and the raw material chamber (2) are connected by an anion exchange membrane (6), and the raw material chamber (2) and the cathode chamber (3) are connected by a cation exchange membrane (7).

6. The method for preparing high-purity trihydroxyethylmethylammonium hydroxide according to claim 1, characterized in that: The mass concentration of trihydroxyethyl methyl quaternary ammonium salt in the raw material chamber is 12.5-15%.

7. A high-purity quaternary ammonium base, characterized in that: It is prepared by the method for preparing a high-purity trihydroxyethylmethylammonium hydroxide according to any one of claims 1-6.

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