Modeling of the Surface Annihilation of Excess Self-Interstitials Generated by Gold Diffusion into Silicon

Abstract

Based on the kick-out mechanism, we have modeled the time evolution of the Si selfinterstitial supersaturation during gold diffusion from evaporated surface layers into silicon substrates. The model comprises a limited annihilation velocity v, of self-interstitials at the Si surface, which accounts for the gradual increase of the Au boundary concentration observed during rapid thermal annealing at higher temperatures and furnace annealing at lower temperatures. Experimental data were fitted by computer simulation of the Au diffusion process. An approximate analytical expression describing the increase of the Au boundary concentration with time is also given. We obtain v 1 = 1.35 x 1011 exp(-3.91 eV/kBT) ms-1 for gold-covered {100}-oriented Si surfaces between 845°C and 1119'C.