Preparation method of ultra-high purity hydrofluoric acid

Abstract

The invention discloses a preparation method of ultra-high purity hydrofluoric acid. The method comprises the following steps: (1) vaporizing anhydrous hydrogen fluoride, doping fluorine-containing gas containing one or more of fluorine gas, nitrogen trifluoride and oxygen difluoride to obtain first mixed gas; (2) introducing the first mixed gas into a plasma generating device to convert the impurity arsenic trifluoride, contained in the first mixed gas, into arsenic pentafluoride to obtain second mixed gas; (3) washing the second mixed gas with an aqueous solution containing metal fluoride toobtain purified hydrogen fluoride, and controlling the temperature of the aqueous solution, wherein the arsenic pentafluoride in the second mixed gas is converted into arsenate and retained in waterin the washing process; (4) selectively repeating the step (2) and the step (3); (5) dissolving the ultra-high purity hydrogen fluoride in the water and filtering to obtain purified hydrofluoric acid.The method provided by the invention is simple, efficient and low in cost, can realize continuous production, and does not bright an adverse effect to the subsequent application; furthermore, the method does not produce hazardous chemical wastes, thus being less in harm to the environment.

Description

Technical field [0001] The invention belongs to the field of purification of hydrofluoric acid, and specifically relates to a preparation method of ultra-high purity hydrofluoric acid. The ultra-high purity hydrofluoric acid is mainly used in the integrated circuit industry and the analysis industry. Background technique [0002] With the development of China's electronics industry, the integrated circuit industry has also developed rapidly with the support of the state. TSMC, Samsung Electronics, Texas Instruments, Intel, SMIC, Unigroup, UMC and other domestic and foreign companies have invested in China to set up factories. In the next 10 years, more than 60% of the world’s 12-inch or more semiconductor production lines will be invested in China. Following this, the corresponding semiconductor industry chain will be transferred to China as a whole, such as polishing wafers, photoresists, ultra-high purity wet Electronic chemicals, ultra-high purity special gas and ultra-high p...

AI Technical Summary

Problems solved by technology

The main difficult-to-remove impurity in ultra-high-purity electronic-grade hydrofluoric acid is arsenic, and its main form is arsenic trifluoride, and arsenic trifluoride can form an azeotrope with anhydrous hydrogen fluoride, so it cannot pass the general Methods such as rectification, gas absorption and other processes to remove it

Based on this, a chemical oxidation method has been proposed in the art to remove impurity arsenic for the above phenomenon. Specifically, the chemical oxidation method mainly uses hydrogen peroxide or potassium permanganate as an oxidant to oxidize arsenic trifluoride to arsenic pentafluoride, and further form However, due to the low oxidation potential of hydrogen peroxide or potassium permanganate, longer reaction time and higher reaction temperature are required, and the addition of hydrogen peroxide or potassium permanganate will bring other disadvantages Influence, for example, for hydrogen peroxide, it needs to be added to a higher content to effectively remove arsenic, and a certain amount of hydrogen peroxide is contained in the final hydrofluoric acid, so that the silicon etching solution composed of hydrofluoric acid and nitric acid will be It leads to slow corrosion of silicon wafers, and even the phenomenon that it cannot be corroded; for potassium permanganate, it will bring pollution to the purification of potassium and manganese in hydrofluoric acid, and increase the cost of purification. At the same time, the addition of high-concentration potassium permanganate It will also bring other problems, such as the difficult disposal of the kettle liquid and the formation of chemical hazardous waste. Therefore, the use of potassium permanganate to remove arsenic is a non-green and environmentally friendly production process