Initial oxidation of silicon (100): a unified chemical model for thin and thick oxide growth rates and interfacial structure

A model for silicon oxidation that invokes dissociative chemisorption of molecular oxygen at the interface between silicon dioxide and silicon is described. The model accounts for a self-limiting oxide film thickness of 0.5-0.6 nm (for oxidations performed at temperatures sufficient to dissociate surface dimers and permit oxygen penetration of the substrate beyond a single monolayer of suboxide). Detailed examination of the model suggests a mechanism for an inherent oxide/silicon interface roughness of approximately one atomic diameter. Kinetic rate equations developed from the model successfully account for the observed power law dependence of rate on oxygen partial pressure. These relationships were used in the derivation of an expression for the variation of oxide film growth rate with overlying oxide thickness. The relationship is tested against experimental observations reported in the literature and found to give an excellent fit.