The Effects of Trace Amounts of Water on the Thermal Oxidation of Silicon in Oxygen

Abstract

The significance of the addition of 25 ppm of H2O to O2 has been studied for the thermal oxidation of (100), (110), and (111) oriented silicon. With 25 ppm water addition to O2 a sharp increase in the over-all rate of oxidation was observed for each orientation and experimental temperature (800°, 927°, and 996°C). From data analysis in terms of a linear-parabolic oxidation law, orientation effects were found for both the linear and parabolic rate constants and for both dry O2 and H2O added oxidations. The major effect of trace H26 appears to be on the parabolic rate constants. The experimentally derived kinetic constants are interpreted in terms of surface geometry for the linear rate constants and in terms of the SiO2 structure for the parabolic rate constants. The large kinetic effects observed with trace amounts of H2O might be a cause for the disparity of literature results for dry thermal oxidation of silicon. © 1974, The Electrochemical Society, Inc. All rights reserved.