KINETICS AND MECHANISM OF LOW-TEMPERATURE ATOMIC OXYGEN-ASSISTED OXIDATION OF SIGE LAYERS

The rates of low temperature atomic oxygen-assisted oxidation of strai ned epitaxial Si1-xGex (x = 0.05, 0.1, and 0.2) layers have been measu red and compared with the rate of oxidation of pure Si. We show that i n the linear regime, the oxidation rate of the SiGe layer increases wi th the Ge concentration in the alloy. On the other hand, Ge/Si (100) s tructures have been oxidized. We show that this oxidation leads to the formation of pure SiO2 oxide and that the nonoxidized Ge layer is sti ll present at the SiO2/Si interface. The oxidation rate of Si is not a ffected by the presence of the pure Ge interface layer. This, together with the results of SiGe oxidation, allows us to conclude that the Si Ge oxidation rate is enhanced by the presence of Ge in the SiGe alloy. This can be explained by the fact that Si-Ge bonds are weaker than th e Si-Si bonds. For longer oxidation times, the oxidation kinetics of S iGe layers follow a parabolic regime. We show that the parabolic const ant strongly depends of the composition of the oxide layer. (C) 1998 A merican Institute of Physics.