Isotopic substitution of N, O, and Si in the thermal oxidation of nitrogen-deposited silicon

Nitrogen was deposited on the surface of Si(100) wafers by ion implantation at a very low energy (approximately 20 eV), at fluences between 1 and 10x1 0(14) cm(-2). The samples were thermally oxidized in dry O-2 at temperature s between 800 and 1050 degrees C. Atomic transport of the chemical species involved in the process was investigated by isotopic tracing of N, O, and S i, using depth profiling with nanometric resolution. The obtained results i ndicate that: (i) the nitrogen atoms deposited on the Si surface are redist ributed during thermal oxidation in O-2 within the silicon oxide (oxynitrid e) film, with maxima at the near-surface and near-interface regions; (ii) d uring growth, O is fixed not only in the near-interface and near-surface re gions like in the thermal growth of SiO2 films on Si, but also in the bulk of the growing oxide (oxynitride) film; and (iii) Si is immobile during the thermal oxidation process. The observed modifications in the mechanisms of thermal growth of SiO2 (SiOxNy) films on Si due to the presence of N are d iscussed. (C) 1999 American Institute of Physics.