Formation of Complexes of Phosphorus and Boron Impurity Atoms in Silicon

Abstract— We have studied the effect of high phosphorus concentration on the diffusion of boron impurity atoms in silicon and, vice versa, the effect of boron on phosphorus diffusion in the silicon lattice. The results demonstrate that boron diffusion in silicon predoped with a high phosphorus concentration is accompanied by an appreciable increase in the concentration of electrically active boron. In addition, phosphorus diffusion in silicon predoped with a high boron concentration is accompanied by a redistribution of boron atoms. The results obtained in this study can be rationalized in terms of the interaction between boron and phosphorus ions during diffusion, which changes the impurity concentration profile and leads to the formation of [P+B–] quasi-neutral complexes in the silicon lattice. The data obtained in this study have been used to calculate the concentration of [P+B–] neutral complexes (~1020 cm–3) and the energy of formation of such complexes (~0.59 eV). The formation of complexes has been shown to be accompanied by an increase in carrier mobility.