Preparation method of electronic grade hydrofluoric acid

Abstract

A preparation method for electron-grade hydrofluoric acid comprises the following steps: introducing an industrial waterless hydrogen fluoride liquid and pure water into a rectifying tower, so as to form hydrofluoric acid with a first concentration; then adding a hydrogen peroxide solution for obtaining arsenic and silicon impurities in hydrofluoric acid, and then performing rectification; condensing the hydrogen fluoride gas obtained through rectification to form a hydrofluoric acid liquid, performing first filtration, and performing absorbing by utilizing pure water to form hydrofluoric acid with a second concentration, and performing second filtration, so as to obtain the electron-grade hydrofluoric acid product; and absorbing tail gas with pure water, so as to prepare industrial-grade hydrofluoric acid. The preparation technology is simple, and no extra impurities are introduced; the prepared electron-grade hydrofluoric acid reaches international standard SEMI-C7 standard of semiconductor equipment and materials; the yield is high and the cost is low; and by employing one production process, the electron-grade hydrofluoric acid and analytically-pure-grade hydrofluoric acid can be both prepared.

Description

technical field

[0001] The invention belongs to the field of chemical production, and in particular relates to a method for preparing electronic-grade hydrofluoric acid. Background technique

[0002] Electronic grade hydrofluoric acid is a strong acid cleaning agent and corrosive agent, mainly used in the production of VLSI. At present, the main production method of electronic grade hydrofluoric acid is as follows: firstly, chemical pretreatment of industrial anhydrous hydrofluoric acid, followed by rectification, then cooling the obtained hydrogen fluoride gas, absorbing it with pure water, finally filtering and filling. Since the presence of impurity arsenic has a serious impact on the performance of electronic devices, the removal of arsenic is a key issue in the purification process of hydrofluoric acid. The usual method is to use an oxidant to convert trivalent arsenic impurities into pentavalent arsenic with a high boiling point. Compounds, commonly used oxidants are ...

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