Gas Phase Composition in the Low Pressure Chemical Vapor Deposition of Silicon Dioxide

Abstract

The gas phase composition during the low pressure chemical vapor deposition of silicon dioxide from silane and oxygen at 360°C has been studied as a function of oxygen to silane mole ratio. The total input flow was constant at 100 sccm. For each mole ratio, the system pressure, deposition rate, and exhaust gas composition were measured. Hydrogen was the major gaseous reaction product. A small amount of water was produced in a secondary reaction. Pressure variation with oxygen to silane ratio has been interpreted in terms of the variation of the exhaust gas viscosity with its composition. A theoretical calculation of the pressure in the system has shown good agreement with the experimental result. The dependence of total reaction efficiency and wafer reaction efficiency on was determined and used to deduce the efficiency of the reaction which occurs on other surfaces in the system or in the gas phase.