Mitsui Toatsu Chemicals, Incorporated

Toshihiko Nishitsuji

Isao Harada

Naruyuki Iwanaga

Akio Kikkawa

Hiroyuki Hyakutake

Yukihiro Yoda

Nobuhiko Koto

This invention relates to a process for obtaining a high purity nitrogen trifluoride gas which is used as a dry etching agent for semiconductors or a cleaning gas for CVD apparatus, etc., particularly to a process for removing oxygen difluoride. This is a process for purifying a nitrogen trifluoride gas by, after removing hydrogen fluoride from a nitrogen trifluoride crude gas, contacting with at least one aqueous solution containing one selected from the group consisting of sodium thiosulfate, hydrogen iodide and sodium sulfide.

Process for purifying nitrogen trifluoride gas

Method of liquefying and condensing nitrogen trifluoride and a method of

The method for preparing a gaseous metallic floride is here disclosed which comprises reacting a metal or its oxide with a fluorine gas or nitrogen trifluoride gas, the aforesaid method being characterized by comprising the steps of mixing the metal or its oxide with a molding auxiliary comprising a solid metallic fluoride which does not react with fluorine and nitrogen trifluoride; molding the resulting mixture under pressure; and contacting the molded pieces with the fluorine gas or nitrogen trifluoride gas, while the molded pieces are heated.

Method for preparing gaseous metallic fluoride

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Yamaguchi, Japan

Toshihiko Nishitsuji