Thermal Oxidation of Silicon in Nitrous Oxide at High Pressures

Abstract

Thermal oxidation of silicon in nitrous oxide ambient at pressures from 1 to 4 atm has been studied. We show that the oxidation rate is different from the one predicted by the Deal-Grove model for normal oxidation in dry oxygen. In our case, the dependence observed for the oxide thickness as a function of the oxidation time is of the form where is a native oxide thickness. For the temperature range between 900 and 1200°C, and 2 atm of pressure, the activation energy for γ is around 1.18 eV. In addition, the exponential factor β (at 1000°C) varies as the square root of the pressure. These results indicate that thermal oxidation in behaves in a completely different way than normal oxidation, very likely due to the influence of chemical reactions in the gas phase, to the catalytic influence of the interface, and to the incorporation of nitrogen into the oxide film itself. The results presented here establish the basis for the development of a more complete model for thermal oxidation of silicon in a ambient. © 2001 The Electrochemical Society. All rights reserved.