The P diffusion profiles in Si-on-insulator structures were compared with those in bulk Si. The P diffusion was carried out at 900 and 10000C, using a spin-on-glass source. This permitted the obtention of a surface concentration that was near to the solid solubility. The diffusion methods consisted of pre-deposition diffusion in an N2 ambient, and drive-in diffusion in N2 or O2 ambients following short-term pre-deposition. The results showed that pre-deposition diffusion in Si-on-insulator structures was retarded at 900C, as compared with its behavior in bulk Si, while it is not retarded at 1000C. The retardation of diffusion was clearer for Si-on-insulator structures with a thinner active layer and longer diffusion time. After drive-in diffusion at 900C, retardation occurred in an O2 ambient but not in a N2 ambient. The results were explained in terms of the annihilation of excess interstitial Si at Si/SiO2 interfaces in the Si-on-insulator structures.

Retarded Diffusion of Phosphorus in Silicon-on-Insulator Structures H.Uchida, Y.Ieki, M.Ichimura, E.Arai: Japanese Journal of Applied Physics - 2, 2000, 39[2B], L137-40