JPH0213029B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a novel production method for obtaining highly pure quaternary ammonium hydroxide from quaternary ammonium salt. [Prior art and problems] Quaternary ammonium hydroxide aqueous solution is used as an organic alkaline agent that does not contain metal ions, such as IC,
Applications for cleaning agents for semiconductor substrates, resist removers, etc. in the manufacture of semiconductor devices such as LSIs are expanding. In these applications, as devices become more highly integrated, a highly purified quaternary ammonium hydroxide aqueous solution is required that contains very little ionic substances such as anions other than hydroxide ions and metal ions. On the other hand, as a method for producing quaternary ammonium hydroxide, an aqueous solution of quaternary ammonium salts such as quaternary ammonium chloride and quaternary ammonium sulfate is supplied to the anode chamber of an electrolytic cell using a cation exchange membrane as a diaphragm. A method of obtaining an aqueous solution of quaternary ammonium hydroxide from a cathode chamber is known. However, in the production method using such a diaphragm electrolytic cell, anions (hereinafter referred to as impure anions) of the quaternary ammonium salt, which is the raw material supplied to the anode chamber, permeate the diaphragm and diffuse into the cathode chamber. Therefore, there is a problem in that the amount of ionic substances in the quaternary ammonium hydroxide aqueous solution obtained from the cathode chamber is significantly increased. To solve this problem, a quaternary ammonium hydroxide aqueous solution obtained from the cathode chamber is used.
One possible method for purification is to bring it into contact with an OH type ion exchange resin and exchange the contained anions with hydroxide ions, but in order to increase the purity of the quaternary ammonium hydroxide aqueous solution obtained by purification,
It is necessary to suppress the amount of anions other than hydroxyl ions in the ion exchange resin used to an extremely small amount. Therefore, extremely pure regenerant and water must be used to purify the OH type ion exchange resin used, which is disadvantageous in industrial implementation. [Means for Solving the Problems] The present inventors have developed a method for obtaining highly pure quaternary ammonium hydroxide by refining quaternary ammonium hydroxide using an OH type ion exchange resin in the above electrolysis. Regarding methods that can be implemented economically,
I have done extensive research. As a result, two or more cation exchange membranes are arranged between the anode and the cathode to form a cathode chamber and an intermediate chamber adjacent to the cathode chamber, and a quaternary ammonium hydroxide aqueous solution is supplied to this intermediate chamber. At the same time, the quaternary ammonium salt aqueous solution in the intermediate chamber is brought into contact with the OH type ion exchange resin, and impure anions present in the intermediate chamber are removed while electrolysis is carried out. By doing this, extremely high purity hydroxide can be obtained without having to highly purify the ion exchange resin as in the case of purifying the quaternary ammonium hydroxide obtained from the cathode chamber with an OH type ion exchange resin. The inventors discovered that quaternary ammonium can be obtained from the cathode chamber and completed the present invention. The present invention provides an electrolytic cell in which at least two cation exchange membranes are arranged between an anode and a cathode to form an anode chamber, an intermediate chamber, and a cathode chamber. The quaternary ammonium salt aqueous solution is supplied while being in circulating contact with the ion exchange resin, and the quaternary ammonium salt aqueous solution is supplied to the chamber adjacent to the anode side with respect to the intermediate chamber to perform electrolysis, thereby producing the quaternary ammonium hydroxide aqueous solution from the cathode chamber. 1 is a method for producing a high-purity quaternary ammonium hydroxide aqueous solution. In the present invention, the raw material quaternary ammonium salt has the general formula

〔effect〕

As can be understood from the above explanation, according to the method of the present invention, even if an OH-type ion exchange resin purified with a low-purity regenerant such as general-purpose caustic soda is used, extremely high purity hydroxylated ion exchange resin can be obtained. It is possible to obtain tetraammonium and economically produce quaternary ammonium hydroxide. [Examples] Examples are shown below to specifically explain the present invention, but the present invention is not limited to these Examples. Example 1 Cation exchange membrane (manufactured by Tokuyama Soda Co., Ltd.), Neocepta
Using a three-chamber electrolytic cell as shown in Figure 1 using two sheets of C66-10F), a 5% aqueous solution of tetramethylammonium chloride is placed in the anode chamber of the electrolytic cell, and 1% water is placed in the cathode chamber and intermediate chamber. Tetramethylamnium oxide was supplied respectively, and the intermediate chamber solution was passed through an ion exchange resin column filled with a commercially available I-type OH-type anion exchange resin installed outside the electrolytic cell, and then circulated back to the intermediate chamber. While doing so, electrolysis was carried out. Electrolysis was carried out at a current density of 20 A/dm ² , and the electrolysis was terminated when the concentration of tetramethylammonium hydroxide in the cathode chamber reached approximately 5%. The Cl ^- concentration in 5% tetramethylammonium hydroxide obtained from the cathode chamber was 0.01 ppm. Incidentally, the type I ion exchange resin was obtained by ion exchange membrane method salt electrolysis upon use. After converting into OH type using 5% NaOH solution, it was produced using a hot bed type ion exchange resin column. Using pure material (specific resistance of 10 MΩ-cm or more), NaOH was extruded and washed with water until Na ⁺ ions became 0.01 ppm or less (by atomic absorption spectrometry). Comparative Example Using the same electrolytic cell as in Example 1,
Electrolysis was carried out under the same conditions as in Example 1 except that % tetramethylammonium hydroxide was not treated with an OH type ion exchange resin. As a result, the Cl ^- concentration in 5% tetramethylammonium hydroxide produced in the cathode chamber was 0.8 ppm.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a typical embodiment of an electrolytic cell used in the present invention. In the figure, 1 is an electrolytic tank;
2 is an anode, 3 is a cathode chamber, 4, 4' is a cation exchange membrane, 5 is an intermediate chamber, 6 is an anode chamber, 7 is a cathode chamber, 8 is a cathode chamber
OH type ion exchange resin layer, 9 indicates a circulation line, respectively.

Claims (1)

[Claims] 1. In an electrolytic cell in which at least two cation exchange membranes are arranged between an anode and a cathode to form an anode chamber, an intermediate chamber, and a cathode chamber, a quaternary ammonium hydroxide aqueous solution is added to an OH type ion exchange resin in the intermediate chamber. A quaternary ammonium hydroxide aqueous solution is obtained from the cathode chamber by supplying the aqueous solution of quaternary ammonium salt to a chamber adjacent to the anode side with respect to the intermediate chamber and performing electrolysis. A method for producing a high-purity quaternary ammonium hydroxide aqueous solution.