The behavior of B in degenerately doped Czochralski material was studied after extended annealing at temperatures ranging from 750 to 900C in a N ambient. The results of secondary ion mass analyses revealed an accumulation of B atoms near to the Si surface. On the basis of the defect morphology, as observed using high-resolution electron microscopy, it was concluded that degenerate Si was saturated with interstitial defect species during extended annealing. Point defect reaction and dynamic clustering models suggested that an accumulation of B near to the Si surface was due to a B out-diffusion which was driven by the difference in the chemical potential of B saturation between the bulk and surface regions.

W.Wijaranakula: Applied Physics Letters, 1993, 62[23], 2974-6