Studies of the diffusion behavior of dopants and neutral impurities have revealed that vacancies and self-interstitials coexist in Si at high temperatures. On the basis of this conclusion, the effect of these point defects upon SiO2 precipitate growth was investigated at temperatures ranging from 400 to 1200C. It was assumed that these point defects played an essential role in providing strain relief during SiO2 precipitate growth. The manner in which the point defect concentrations changed in the vicinity of the precipitate was modelled, and it was shown that these local variations affected the flux of the O atoms via an O/point-defect reaction at the precipitate surface. In the 2 extreme cases which were studied (vacancies only and interstitials only), the model predicted an O flux which was lower than that limited by O diffusion alone. For the vacancy-only case, this difference amounted to some orders of magnitude, indicating that a V-only model was not capable of fitting experimental data. However, the interstitials-only model predicted a flux which was only 30% lower than that limited by O diffusion at temperatures as low as 400C. It was concluded that, while vacancies could contribute to some extent, self-interstitials played the predominant role in providing strain relief during the precipitate growth.

W.J.Taylor, T.Y.Tan, U.M.Gösele: Materials Science Forum, 1992, 83-87, 1451-6