Oxygen precipitation in silicon: The role of strain and self-interstitials

Formation of SiO2 precipitates in silicon is associated with a large volume expansion. This leads to the generation of strain and a self-interstitial (I) supersaturation in the Si matrix, which in turn influence both the precipitate nucleation and growth processes. We have obtained an explicit expression correlating the strain to the self-interstitial supersaturation. For nucleation, we obtained an expression of the critical nucleus size containing the contribution of both factors. For growing precipitates, we have found a high I supersaturation at the SiO2-Si interface. This leads to a precipitate growth rate lower than that of the oxygen diffusion limited case. However, the extent of this growth rate lowering is not large, and the precipitate growth can still be regarded as being limited by oxygen diffusion within the accuracy range of most experiments.