The limitation of the Split-Gate MOSFET(SG-MOSFET) at 3.3kV

Abstract

Split Gate MOSFET (SG-MOSFET) is one of the effective way to lower the gate-drain capacitance (CGD). However, the applicability of 3.3 kV SiC MOSFET has not been studied yet. In this paper, comparative study of 3.3 kV 4H-SiC SG-MOSFET was confirmed by TCAD simulation compared with conventional MOSFET (C-MOSFET). As a result, the DC figure of merit (DC-FOM) of the two structures are 747.33 MW/cm2 and 605.39 MW/cm2, respectively, and the high frequency figure of merit (HF-FOM) are 754.66 mΩ·pF and 574.5 mΩ·pF., respectively. Although HF-FOM improved by 24% due to the split gate structure, DC-FOM decreased by 19%. In addition, it does not satisfy the gate oxide reliability and suffered from severe DIBL effect. Therefore, the SG-MOSFET is less effective in improving HF-FOM compared to DC-FOM and causes reliability problems in the 3.3 kV.