Diffusion of Tin into Silicon

Abstract

Diffusion of a neutral impurity (tin) into silicon in the presence or absence of acceptor‐ or donor‐type impurities, such as boron or phosphorus, has been investigated through neutron‐activation analysis. The diffusivity of tin alone in near‐intrinsic silicon is found to be D⁰=32 exp(−98 000/RT)cm²·sec⁻¹. In the simultaneous diffusion of tin and phosphorus, the diffusivity of tin is enhanced. It is found to agree well with the calculated increase of diffusivity, based on the model of increase of total equilibrium lattice vacancy concentration with donor concentration. However, in the simultaneous diffusion of tin and boron, the diffusivity of tin (due to the presence of boron) is found to be approximately the same as that without the boron. Although the acceptor doping is expected to reduce the tin diffusivity slightly, this effect cannot be ascertained with experimental accuracy.