IEEE Journal of the Electron Devices Society (Jan 2021)
A Novel SiC Asymmetric Cell Trench MOSFET With Split Gate and Integrated JBS Diode
Abstract
A novel high performance SiC asymmetric cell trench MOSFET with split gate (SG) and integrated junction barrier schottky (JBS) diode (SGS-ATMOS) is proposed for the first time. The shielding effect provided by the SG structure not only reduces the gate-drain capacitance ( ${C}_{\mathrm{gd}}$ ) but also alleviates the electric field crowding in the dielectric layer at trench corner. The integrated trench JBS diode bypasses the PiN body diode while obtaining good double protection from the SG and p-type shielding region. Therefore, not only the MOSFET but also diode performance is significantly improved for the proposed structure. Numerical analysis results show that compared with the conventional asymmetric cell trench MOSFET (Con-ATMOS), the high frequency figure of merit (HFFOM1, ${R}_{\mathrm{on}} {\cdot } {C}_{\mathrm{gd}}$ ) is reduced by 92.5% and the Baliga figure of merit (BFOM, ${BV}^{2}/R_{\mathrm{on,sp}}$ ) is increased by 57.2%, respectively. In addition, the forward conduction voltage drop ( ${V}_{\mathrm{F}}$ ), reverse recovery charge ( ${Q}_{\mathrm{rr}}$ ) and peak reverse recovery current ( ${I}_{\mathrm{rrm}}$ ) of the diode are reduced from 3.10V, $1.95\mu \text{C}$ /cm2 and 68.0A for the Con-ATMOS to 1.56V, $0.97\mu \text{C}$ /cm2 and 35.9A for the proposed SGS-ATMOS, respectively. Compared with the Con-ATMOS, the turn-on loss ( ${E}_{\mathrm{on}}$ ) and turn-off loss ( ${E}_{\mathrm{off}}$ ) of the proposed device are reduced by 33.3% and 33.0%, respectively. The ${E}_{\mathrm{on}}$ and ${E}_{\mathrm{off}}$ of the proposed device are also 33.6% and 30.0% off compared with the Con-ATMOS with external JBS diode, respectively. The temperature characteristics of the SGS-ATMOS are also discussed and it is found that the proposed device exhibits good performance at high temperature.
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