Dangers Created in Epitaxial Exhaust Lines by Partially Reacted Process Gases
(Applied Technology Specialists, Inc., Bixby, Oklahoma)
Epitaxial depositions involving materials such as Silane and Phosphine are thermally cracked to produce Silicon or Phosphorus atoms and ions as part of the deposition process. Most of the gases injected into reactors during these operations remain unused and are expelled in the reactor exhaust lines. Cracked and partially cracked fractions, as well as partially reformed compounds, can be deposited on the exhaust line inner walls and are stable only under certain conditions and can unexpectedly react violently when these conditions change. These materials are often referred to as meta stable compounds and have been the cause of hundreds of millions of dollars in property and product losses. This paper will review one or more cases where these compounds have been the source of property loss and to present several solutions to minimize or eliminate the dangers they produce.