Rate enhancement during thermal oxidation of Ge+-implanted silicon

The oxidation kinetics of Ge+-implanted Si(1 0 0) were determined over a temperature range of 900-1100 deg. C in both dry and wet O2 conditions. It will be shown that the implanted Ge substantially enhances the kinetics (compared to that in virgin Si) under certain conditions. Segregation of the Ge during oxidation produces a 'snow-plow' effect that forms a highly enriched Ge layer, Ge xSi1-x, at the Si/SiO2 interface. The interfacial concentration of Ge (developed by the competition between the oxidation rate and Ge diffusivity in Si) is shown to be a critical parameter in determining whether or not the oxidation kinetics are affected. High depth resolution Rutherford backscattering spectrometry (RBS) measurements were used to determine the Ge composition, as well as the oxide thickness. Since fast oxidation kinetics favors a high interfacial concentration of Ge, an enhanced oxidation rate was readily observed for wet conditions. The slower kinetics associated with dry oxidation made it difficult to observe any rate enhancement. However, enhanced oxidation under these conditions will be reported and shown to be consistent with a previous model proposed to account for this effect. Computer simulations of the processes will be presented and shown to be in qualitative agreement with the results