Time dependence of the oxygen exchange O-2 <-> SiO2 at the SiO2-Si interface during dry thermal oxidation of silicon

During dry thermal oxidation of silicon oxygen exchange reactions may occur between oxygen molecules (O-2<->O-2, catalyzed by the SiO2) or between oxy gen from the gas phase and the oxygen in SiO2 (O-2<->SiO2), both at the sur face and at the Si-SiO2 interface. We found that the oxygen exchange rate a t the Si-SiO2 interface is at least 25% of the oxygen uptake rate, requirin g the movement of oxygen both from the surface to the interface, and from t he interface to the surface. The oxygen exchange at the interface is furthe r evidence in favor of the presence of a reactive interfacial layer between the growing oxide and the silicon substrate. (C) 1999 American Institute o f Physics. [S0021-8979(99)08514-X].