Surface Silicon Crystallinity and Anomalous Composition Profiles of Buried SiO₂ and Si₃N₄ Layers Fabricated by Oxygen and Nitrogen Implantation in Silicon

Abstract

Buried SiO 2 and Si 3 N 4 with residual crystalline surface silicon were fabricated by implantation of O + , O 2 + , N + and N 2 + into single-crystal silicon with 0.6–3.0×10 18 atom/cm 2 dose at an energy of 70–150 keV/atom. The implanted silicon wafers were annealed at 1150°C to recover the surface silicon crystallinity and to ensure good Si–O and Si–N bonds. After this, high-quality crystalline silicon layers were grown epitaxially on the implanted surface. The surface silicon damage and the buried layer composition profiles were measured reliably by the Rutherford backscattering method together with the channeling technique. In the buried layers, the O/Si ratio did not exceed the stoichiometric ratio of 2.0 for SiO 2 even before annealing. However, the N/Si ratio exceeded the stoichiometric ratio of 4/3 for Si 3 N 4 .