Investigations of 4H-SiC trench MOSFET with integrated high-K deep trench and gate dielectric

Abstract

This paper proposes and investigates a novel 4H-SiC trench MOSFET (TMOS) with integrated high-K deep trench and gate dielectric (INHK-TMOS). The integrated high-K (INHK) consists of a high-K gate dielectric and an extended high-K deep trench dielectric in the drift region. Firstly, the high-K gate dielectric together with the metal-forming high-K metal gate structure, which increases the gate oxide capacitance (C_OX), reduces the threshold voltage (V_TH) and the specific on-resistance (R_on,sp). Secondly, the extended high-K deep trench dielectric not only modulates the electric field in the drift region by introducing a new electric field peak at the bottom of the high-K deep trench dielectric, thereby enhancing the breakdown voltage (BV), but also improves the doping concentration (N_D) of the drift region by the assist depletion effect of the high-K dielectric, further optimizing the forward conduction characteristics. Simulation results demonstrate that when compared to the conventional TMOS, the INHK-TMOS using HfO₂ exhibits a 52.6% reduction in V_TH, a 52.1% reduction in R_on,sp, a 20.3% increasement in BV and a 202.3% improvement in figure of merit.