On the formation of silicon oxynitride by ion implantation in fused silica

Abstract

The formation of silicon oxynitrides and nitrogen gaseous compounds as a consequence of implantation of nitrogen ions in silica glasses was investigated by XPS analysis. The presence of gaseous compounds is supported by the analysis of the effect of a double implantation: a nitrogen implantation followed by an argon irradiation. Moreover SEM analysis shows, for doses higher than 6 × 10 17 N cm −2, a surface morphology characterized by blisters, which can be also ascribed to NO or N 2 molecules. These structures are absent in the case of neon implantations. The distribution of nitrogen as a function of the implantation dose was measured by SIMS. With a dose >5 × 10 16 cm −2, the nitrogen distribution showed a flat profile limiting the maximum attainable nitrogen concentration and, consequently, the stoichiometry of the SiO x N y compounds. An increase of the nitrogen concentration was obtained for nitrogen implantations in 29Si-preimplanted silica glasses. The nitrogen profile followed the distribution of the preimplanted silicon.