Anomalous Diffusion of Phosphorus into Silicon

Abstract

Lattice strains induced by diffusion of phosphorus, arsenic, antimony and tin into silicon are studied through an X-ray double crystal spectrometer. This quantitative experiment gives that the amount of lattice strain induced by diffusion of impurity depends both on the size of impurity atoms diffused into silicon and on the impurity concentration, which agrees with the equation by S. Prussin et al. It also leads to the result as follows; the lattice strain in the diffused layer is compensated in the case of the phosphorus content less than 4×10²⁰ atoms/cm³ by diffusing both tin, whose atomic radius is larger than that of silicon, and phosphorus with smaller radius. Anomaly in the diffraction pattern is also observed in the case of anomalous diffusion of phosphorus under high vapor pressure of phosphorus.