Chemistry of silicon oxide annealed in ammonia

This paper presents some qualitative correlations among the chemical contents in thermal oxynitride and re-oxidized oxynitride films. By performing Auger electron spectroscopy, infrared absorption measurements and analyses of the chemical composition of the thin films, mechanisms of the chemical reactions during the thermal nitridation are proposed. For the thermal nitridation of silicon oxide in ammonia four different mechanisms exist: (a) an oxidizing reaction at the Si/SiO₂ interface at an early stage of nitridation; (2) a replacement reaction at the interface for prolonged nitridation; (3) a replacement reaction in the bulk oxide; (4) cross-linking reactions for heavy nitridation or post-nitridation in inert ambient. © 1993.