Effect of the Field Oxidation Process on the Electrical Characteristics of 6500V 4H-SiC JBS Diodes

The effect of the field oxidation process on the electrical characteristics of 6500V 4H-SiC JBS diodes is studied. The oxide thickness and field plate length have an effect on the reverse breakdown voltage of the SiC JBS diode. According the simulation results, we choose the optimal thickness of the oxide layer and field plate length of the SiC JBS diode. Two different field oxide deposition processes, which are plasma enhanced chemical vapor deposition (PECVD) and low pressure chemical vapor deposition (LPCVD), are compared in our paper. When the reverse voltage is 6600V, the reverse leakage current of SiC JBS diodes with the field oxide layer obtained by LPCVD process is 0.7 μA, which is 60% lower than that of PECVD process. When the forward current is 25 A, the forward voltage of SiC JBS diodes with the field oxide layer obtained by LPCVD process is 3.75 V, which is 10% higher than that of PECVD process. There should be a trade-off between the forward and reverse characteristics in the actual high power and high temperature applications.