Study on P-Well Surface Doping on the Static Characteristics and Avalanche Robustness of Planar SiC-MOSFET

Ion implantation can achieve doping in the P-base region in the fabrication of planar gate silicon carbide (SiC) MOSFET. The doping concentration of the P-base surface region is primarily determined by the dose of the minimum implantation energy during the ion implantation process. Therefore, manipulating the dose of minimum implantation energy can regulate the doping concentration on the surface of the P-base. In this study, Sentaurus TCAD was used to investigate the influence of P-base surface doping concentration on the static characteristics and avalanche robustness of SiC MOSFET. The simulation results indicate that an increase in the doping concentration of the P-base surface region leads to a rise in both the threshold voltage and the on-resistance. There is no significant impact on the device's breakdown characteristics if the P-base surface doping exceeds 9.3e16 cm^-3. Furthermore, the result of the unclamped inductive switching (UIS) test simulation revealed that the increase of the surface doping can cause a decline in electron current during the avalanche event, accompanied by a reduction in the duration of the avalanche event, indicating an enhancement of the device's robustness.