Oxidation-enhanced diffusion of arsenic and phosphorus in near-intrinsic 〈100〉 silicon

Abstract

Oxidation‐enhanced diffusion (OED) of phosphorus and arsenic in 〈100〉‐oriented silicon has been characterized under low‐concentration doping conditions. The first indisputable evidence of arsenic OED in silicon has been obtained. The impurities were introduced by ion implantation, and thermally diffused profiles under oxidized and nonoxidized silicon surfaces were obtained simultaneously. Samples were beveled and the doping profiles were characterized by means of spreading resistance. Because of the close proximity of intrinsically diffused and OED profiles, the relative change in diffusivity could be accurately obtained. Both for phosphorus and arsenic the enhancement decreases as temperature increases, a behavior that is in agreement with previously reported data for boron. On the basis of the present data, it can be concluded that (a) the diffusion mechanisms are basically the same for all three elements and (b) the impurity diffusion mechanism involves two types of point defects in silicon, and the oxidation process increases the concentration of only one of these defects.