A novel SiC superjunction MOSFET with three-level buffer and unipolar channel diode

A novel SiC trench superjunction MOSFET with an integrated unipolar channel diode and three-level buffer (DioSJ-MOS) is proposed, which features an additional planar channel and a three-level buffer (TLB). The planar channel brings the effect of dual-channel forward conduction and unipolar reverse conduction, reducing specific on-resistance and improving third quadrant performance. The TLB composed of P-pillar, P + body and thickened oxide layer optimizes the in-body and gate-oxide electric field, improving gate oxide reliability, enhancing device breakdown voltage and lessening the gate-drain coupling. Furthermore, an embedded channel diode with low potential barrier for electrons transport replaces internal parasitic diode successfully. Compared with conventional MOSFET (SF-MOS) and trench/planar MOSFET (TP-MOS), DioSJ-MOS exhibits a lower specific on-resistance (1.08 mΩ cm2), an improved gate oxide electric field (2.6 MV/cm) and a better third quadrant performance （1.56 V） due to TLB structure and unipolar channel diode. Meanwhile, the gate to drain charge (QGD) and capacitance (CGD) of DioSJ-MOS are significantly reduced by about 3 × and 4 × in comparison with TP-MOSFET. Therefore, the overall enhanced performance indicates that DioSJ-MOS is more attractive device in high-voltage, high-reliability and high-frequency applications.