On the role of self-interstitials in impurity diffusion in silicon

The question of whether the monovacancy or the self-interstitial is the point defect responsible for impurity diffusion is reviewed in the light of buried marker diffusion experiments and irradiation-enhanced diffusion data. It is concluded that coupled vacancy-impurity diffusion is the preferred interpretation, but no definite conclusions can be drawn. However, the role of the self-interstitial in diffusion is proposed through a model which assumes that during oxidation, exchanges can take place between vacancies, self-interstitials, impurity interstitials, and substitutional impurities. By assuming a partial interstitialcy diffusion model it is shown that ?10-20% of the impurity flux during nonoxidizing diffusion conditions is due to impurity interstitials displaced by self-interstitials in equilibrium in the silicon. Calculations of impurity interstitial formation energies are consistent with the degree of oxidation enhanced diffusion measured for boron, phosphorus, and arsenic.

Duke Scholars

Author Richard B. Fair Electrical and Computer Engineering