A quantitative model for near-surface redistribution of doping impurity in Si in the course of proton-stimulated diffusion was developed for the first time. According to the model, the near-surface peak of the impurity concentration was caused by the migration of neutral impurity plus self-interstitial pairs to the surface with subsequent decomposition of these pairs and accumulation of the impurity at the Si surface within a thin layer (referred to as a δ-doped layer). The depletion and enhancement regions that were found deeper than the near-surface concentration peak were caused by the expulsion of ionized impurity by an electric field from the near-surface region of the field penetration. The field appeared due to the charge formed in the natural-oxide film at the Si surface as a result of irradiation with protons. The diffusion-kinetic equations for the impurity, self-interstitials, vacancies, and impurity plus self-interstitial pairs were solved numerically simultaneously with the Poisson equation. It was shown that the results of the calculations were in quantitative agreement with experimental data on the proton-stimulated diffusion of B impurity in the near-surface region of Si.

Simulation of Near-Surface Proton-Stimulated Diffusion of Boron in Silicon. O.V.Aleksandrov, V.V.Kozlovski: Semiconductors, 2008, 42[3], 257-62