A structural and process solution is proposed that can markedly improve the dielectric breakdown strength of thermal oxide on n-type 4H-SiC. A polycrystalline silicon gate MOS capacitor fabricated using this new process had a breakdown strength of more than 13 MV/cm even after it underwent a power MOSFET fabrication process that included rapid-thermal contact annealing. The thermal budget of this new process can significantly improve some oxide properties.