Study of oxygen transport processes during plasma anodization of Si between room temperature and 600 °C

Abstract

Studies of oxygen transport mechanisms during plasma anodization of Si have been carried out using a combination of 18O tracing techniques and nuclear microanalysis. A thin 18O-enriched ZrO2 overlay film has been used as a source of oxygen tracers during subsequent plasma anodization of Si. The enhancement effect of the zirconia layer on the kinetics of Si anodization allows one to study the mechanisms of Si anodization between room temperature and 600 °C. Results of the 18O depth distributions show that the order of oxygen atoms is largely preserved in the SiO2 and that oxygen ions migrate during film growth. For the temperature range (25–600 °C) studied the microscopic mechanism of oxygen transport during plasma anodization of Si involves a short-range oxygen ion migration, in contrast to the case of high-temperature thermal oxidation. The contribution of a pure thermal process via the diffusion of neutral oxygen species is negligible compared to the high-field-assisted oxygen ion migration in these plasma anodization experiments.