Thermal oxidation of Ge-implanted Si: Role of defects

Thermal oxidation of Ge-implanted Si (SiGe) was carried out in dry O-2 at 1073, 1173, and 1273 K for various times. Rutherford backscattering spectrometry in random and channeling geometry was used to characterize the SiO2 thickness and composition of the Si1-xGex layer to determine the oxidation kinetics and to monitor changes in the Ge distribution in the implanted layer. Oxide thicknesses obtained in this work were compared with published results for SiGe from the Deal and Grove (DG) model perspective with modified constants for SiGe oxidation. Reasonable agreement between the data and the "ideal" DG curve is achieved, namely, the residuals are randomly scattered around zero, but the results of a statistical test suggest that the DG model equation explains only 70% of the variation of the data. The possible influence of point defects in implanted samples on the oxidation rate was further tested by preannealing the implantation damage. It was found that oxide thicknesses measured for preannealed samples differ from those for as implanted samples by less than 10%, which cannot explain the observed discrepancies with the DG model. We thus suggest that the implantation damage is being annealed during the thermal oxidation itself. (C) 2011 Elsevier B.V. All rights reserved.