Silicon Defect Structure Induced by Arsenic Diffusion and Subsequent Steam Oxidation

Abstract

Misfit dislocation nets are known to occur when very high amounts of phosphorus and boron are diffused into silicon single-crystal wafers. Diffusion of arsenic in silicon is not known to produce such dislocations. Through transmission electron microscopy it is shown in this paper that diffusion of high amounts (up to 1.6 × 1021 atoms/cm3) of arsenic creates Frank hexagonal loops on (111) planes parallel to the diffusion surface, and stacking faults on the inclined {111} planes, instead of misfit dislocation nets (the latter are still not observed). These faults and loops are found to be extrinsic, and are thought to be due to insertion of extra silicon layers in the matrix where the stacking fault energy is decreased by arsenic atoms. The driving force for the generation of loops and faults is shown to be the concentration gradient rather than fast cooling.