A 1.2 kV SiC MOSFET with Integrated Heterojunction Diode and P-shield Region

A 1.2 kV SiC MOSFET with an integrated heterojunction diode and p-shield region (IHP-MOSFET) was proposed and compared to a conventional SiC MOSFET (C-MOSFET) using numerical TCAD simulation. Due to the heterojunction diode (HJD) located at the mesa region, the reverse recovery time and reverse recovery charge of the IHP-MOSFET decreased by 62.5% and 85.7%, respectively. In addition, a high breakdown voltage (BV) and low maximum oxide electric field (EMOX) could be achieved in the IHP-MOSFET by introducing a p-shield region (PSR) that effectively disperses the electric field in the off-state. The proposed device also exhibited 3.9 times lower gate-to-drain capacitance (CGD) than the C-MOSFET due to the split-gate structure and grounded PSR. As a result, the IHP-MOSFET had electrically excellent static and dynamic characteristics, and the Baliga’s figure of merit (BFOM) and high frequency figure of merit (HFFOM) were increased by 37.1% and 72.3%, respectively. Finally, the switching energy loss was decreased by 59.5% compared to the C-MOSFET.

A Novel MOS-Channel Diode Embedded in a SiC Superjunction MOSFET for Enhanced Switching Performance and Superior Short Circuit Ruggedness

In this study, a novel MOS-channel diode embedded in a SiC superjunction MOSFET (MCD SJ-MOSFET) is proposed and analyzed by means of numerical TCAD simulations. Owing to the electric field shielding effect of the P+ body and the P-pillar, the channel diode oxide thickness (tco) of MCD can be set to very thin while achieving a low maximum oxide electric field (EMOX) under 3 MV/cm. Therefore, the turn-on voltage (VF) of the proposed structure was 1.43 V, deactivating the parasitic PIN body diode. Compared with the SJ-MOSFET, the reverse recovery time (trr) and the reverse recovery charge (Qrr) were improved by 43% and 59%, respectively. Although there is a slight increase in specific on-resistance (RON), the MCD SJ-MOSFET shows very low input capacitance (CISS) and gate to drain capacitance (CGD) due to the reduced active gate. Therefore, significantly improved figures of merit RON × CGD by a factor of 4.3 are achieved compared to SJ-MOSFET. As a result, the proposed structure reduced the switching time as well as the switching energy loss (ESW). Moreover, electro-thermal simulation results show that the MCD SJ-MOSFET has a short circuit withstand time (tSC) more than twice that of the SJ-MOSFET at various DC bus voltages (400 and 600 V).