Segregation and desorption kinetics for evaporation of arsenic from silicon

A significant role of surface segregation in arsenic out-diffusion from silicon is described. After heat treatment of uniformly arsenic-doped silicon in a H2 ambient, the amount of arsenic atoms segregating at the surface is measured using Auger electron spectroscopy. The experimental results are explained by a new model including the segregation effect in the boundary condition in the diffusion equation. Comparing the new model with previous treatments for out-diffusion phenomena, it is indicated that K which has been defined as an evaporation velocity from the solid to the gas phase should be replaced by k1, the rate of the first-order reaction from the solid to the segregation layer at the surface.