| 摘要 |
PURPOSE:To obtain easily high-purity hydrofluoric acid suitable as a detergent for semiconductors, by adding fluorine to hydrofluoric acid containing arsenic compounds as an impurities, reacting fluorine with arsenic compounds and distilling hydrofluoric acid. CONSTITUTION:Fluorine is added to hydrofluoric acid containing arsenic compounds (e.g., AsF3, HAsF6) as impurities, so fluorine is reacted with the arsenic compound. An amount of fluorine added is properly about 50-100ppm when a content of the impurities is <=about 100ppm on the whole. Then, hydrofluoric acid is distilled, to give purified hydrofluoric acid having 10<-4> arsenic concentration level. Water is added to distilled hydrofluoric acid depending upon the use of hydrofluoric acid, so fluorine remaining in hydrofluoric acid is preferably hydrolyzed and removed.
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