Accidental explosions of semiconductor manufacturing gases in Japan

Abstract

This paper presents the results of case studies on accidental gas explosions in the history of advanced technologies using highly reactive gases in Japan. In November 1984, a reservoir cylinder containing mono-germane imported from the United States exploded. This was the first serious explosion due to mono-germane decomposition in Japan. Five years later another explosion due to mono-germane decomposition occurred. These two accidental explosions forced the Japanese government to investigate the decomposition characteristics of semiconductor manufacturing gases. Consequently, it was found that mono-germane decomposed by adding a small amount of energy. Although pure mono-silane does not explode, its mixture with oxidizer explodes in a wide range of mixture compositions. The most serious such accidental explosion occurred at a laboratory of a university in October 1991. The gas which exploded in this case was a mixture of mono-silane and nitrous oxide. One of the major causes was a lack of knowledge on sealing in the check-valve. Besides the explosions, the causes of which were unknown before, explosions of well-known causes have occurred. Based on knowledge accumulated through these accidental explosions, the technologies against explosions have been established for semiconductor tip industries.