Accidental explosions of semiconductor manufacturing gases in Japan

Abstract
The first step to establish a reliable technology is to know hazards through case studies on accidents in the industries to which the technology would contribute. This paper presents the results of case studies on accidental gas explosions in the history of advanced technologies using highly reactive gases in Japan. Accidental explosions due to mono-germane decomposition made Japanese government investigate the decomposition characteristics of semiconductor manufacturing gases. Consequently, it was found that only mono-germane decomposed by adding a small amount of energy. Although pure mono-silane does not explode, its mixture with an oxidizer explodes in a wide range of mixture compositions. At its leakage into ambient air, however, mono-silane does not ignite when its velocity is high. In an explosion caused by a mono-silane leakage, damage became serious due to this characteristic. The unsuitable material in a mono-silane supply system causes it to mix with an oxidizer. A serious accidental explosion occurred when mono-silane unexpectedly mixed with nitrous oxide at a CVD system. Besides of the explosions, the causes of which were unknown before those, explosions by well-known causes have occurred. Based on knowledge accumulated through these accidental explosions, various technologies against explosions have been established for semiconductor tip industries.