Improved oxidation procedures for reduced SiO2/SiC defects

A significant reduction in the effective oxide charge and interface state densities in oxides grown on p-type 6H-SiC has been obtained by lowering the oxidation temperature of SiC to 1050°C. Further improvements are obtained by following the oxidation with an even lower temperature re-oxidation anneal. This anneal dramatically improves the electrical properties of the Si/SiC interface, and substantially lowers the interface state density. The net oxide charge density on p-type 6H-SiC is also lowered significantly, but remains quite high, at 1.0 × 10¹² cm^-2. The interface state densities of 1.0 × 10¹¹ cnr⁻²/eV are approaching acceptable MOS device levels. The breakdown fields of the oxides are also substantially improved by both the lower oxidation temperature and re-oxidation anneal. Using a low temperature oxidation followed by a re-oxidation anneal for MOSFETs results in a room temperature mobility of 72 cm²/V-s, the highest channel mobility reported for SiC MOSFETs to date.