Low-temperature oxidation of SiC surfaces by supercritical water oxidation

The oxidation process on silicon carbide (SiC) surfaces is important for wide bandgap power semiconductor devices. We investigated SiC oxidation using supercritical water (SCW) at high pressure and temperature and found that a SiC surface can be easily oxidized at low temperature. The oxidation rate is 10 nm/min at 400 °C and 25 MPa, equal to that of conventional thermal dry oxidation at 1200 °C. Low-temperature oxidation should contribute to improved performance in future SiC devices. Moreover, we found that SCW oxidation at 400 °C forms a much smoother SiO₂/SiC interface than that obtained by conventional thermal dry oxidation. A higher oxidation rate and smaller microroughness are achieved at a lower oxidation temperature owing to the high density of oxidizers under SCW conditions.