Oxygen diffusion kinetics during SiO2/SiC plasma oxidation

Abstract

SiO2 as the gate dielectric is important for SiC MOSFETs. For the process to obtain SiO2, plasma oxidation as an alternative to conventional thermal oxidation has made some progress. However, the oxygen diffusion kinetics in plasma oxidation have not been systematically studied yet. In this work, the oxygen diffusion behavior in plasma oxidation is investigated by 18O isotope tracing technique and compared with that in thermal oxidation. Two kinetic models are proposed, which consider oxygen exchange between ambient and SiO2, and direct oxygen diffusion in SiO2 in terms of atoms and/or molecules. Moreover, for plasma oxidation, two types of oxygen diffusion have been studied quantitatively. This work unveils the oxygen diffusion mechanism, which would be meaningful for further research of plasma oxidation, such as optimizing conditions, understanding reactions, etc.