Method of refining silicon tetrafluoride gas

摘要

SiF4 gas containing oxygen-containing silicofluoride(s) typified by (SiF3)2O as impurity can be refined to extremely high purity by making the SiF4 gas contact with HF in the presence of a liquid medium having strong affinity for water such as sulfuric acid or phosphoric acid. By reaction with HF, the impurity such as (SiF3)2O is converted to SiF4, while the liquid medium absorbs water formed by the reaction to thereby prevent a reverse reaction between SiF4 and H2O to form (SiF3)2O.