Formation mechanisms and structures of insulating compounds formed in silicon by ion beam synthesis

Abstract

To synthesise buried compound layers, reactive ions C⁺, N⁻ and O₂ ⁺ of energy 200 keV/atom were implanted into (100) single crystal silicon at approximately 500°C. Implanted specimens were annealed at high (≥ 1200°C) temperatures. Rutherford backscattering and channelling techniques were used to study the distributions of the implanted species and annealing of the radiation damage. SIMS provided complementary information on the distribution of light elements in silicon. Cross-sectional TEM was used to identify chemical compositions of buried layers and to assess the quality of silicon overlayer after annealing.

It is demonstrated that oxygen in silicon forms a well defined layer of SiO₂, with a good quality single crystal silicon overlay upon annealing at 1300°C. Nitrogen in silicon can be successfully annealed at 1200°C while no annealing procedure has yet been found for carbon in silicon. Differences and similarities in both the as-implanted and high temperature annealed materials are explained by the mobilities of the impurities in bulk silicon and in the impurity rich and/or compound layers.