Diffusion of boron and phosphorus in dry , wet Ar, and wet ambients was investigated to obtain a formula describing the oxidation enhanced diffusion. At low impurity concentration, the diffusion coefficient is expressed as a function of oxide growth rate, depth, and temperaturewhere is in μm/hr and is in μm. value is for boron and for phosphorus. This equation can be explained by a dual mechanism involving both vacancy and interstitial silicon atoms. A depth dependence of the diffusion coefficient is explained by a model that excess interstitial silicon atoms are captured by vacancies migration into bulk silicon. At high impurity concentration, less enhanced diffusion was observed.