Analytical model for chemical vapor deposition of SiO2 films using tetraethoxysilane and ozone

Abstract

A theoretical model has been developed to analyze chemical vapor deposition (CVD) of SiO2 from tetraethoxysilane (TEOS) and ozone. The model incorporates both homogeneous gas phase reactions and heterogeneous surface reactions. Two new kinetic mechanisms which include parasitic gas phase reactions are proposed to explain the observed decrease in deposition rate of SiO2 films as the temperature is increased. The predicted values from the proposed model are found to agree well with all available experimental results over a wide range of experimental conditions. The effect of parasitic gas phase reactions becomes significantly more pronounced with increasing pressure and temperature. Correlations of experimental data on etch rate with surface concentrations predicted by the model at 60 Torr show that one can improve the film quality by increasing the ratio of O3 to TEOS at the wafer surface, (O3/TEOS)wafer, and the wafer temperature.