New model of the rapid initial oxidation of silicon

Abstract

We propose a new model to explain the high initial oxidation rates observed during thermal oxidation of Si in dry O2. We show how the accumulation of fixed positive charge that develops in the SiO2 during thermal oxidation acts to reduce the concentration of holes at the Si-SiO2 interface and thereby reduces the density of broken Si–Si bonds there. It is believed that the density of broken Si bonds is a controlling factor in the oxide growth rate during the early phase of the oxidation process, when the rate is limited by the interfacial reaction mechanism. We also present experimental evidence that is consistent with the model, and is in good agreement with independent observations of the fixed oxide charge.