The mechanism of impurity diffusion in silicon

Abstract

Abstract The diffusion of doping impurities in silicon is influenced by the oxidation which usually occurs during the diffusion process. In order to accommodate the inward growing oxide excess material flows away from the oxidizing interface which results in an additional component to the impurity flux and in a perturbation of the point defect concentrations in the surface regions. The sense of the perturbation is such that the interstitial concentration is increased or the vacancy concentration is decreased and this results in a change in the value of the diffusion coefficient. From a comparison of the diffusion coefficient obtained under oxidizing and non-oxidizing conditions it is concluded that impurity diffusion in silicon occurs by the interstitially mechanism.