The reasons for inferior electrical properties of nitric oxide (NO) annealed gate oxides compared to gate oxides directly grown in NO are investigated in this paper. Interface roughness is identified as one of the main issues. A significant improvement of the annealed gate oxides is achieved by introducing an initial nitridation step, prior to oxidation and NO annealing. With this additional step, a sandwich (nitridation-oxidation-nitridation) process is developed to improve the SiC-SiO2 interface without the need for lengthy and expensive direct growth in NO.