An Optimized Structure of 4H-SiC U-Shaped Trench Gate MOSFET

In this paper, an optimized structure of 4H-SiC U-shaped trench gate MOSFET (UMOSFET) with low resistance is proposed. The optimized structure adds an n-type region, wrapping the p+ shielding region incorporated at the bottom of the trench gate. The depletion region formed by the p+ shielding region reduces greatly for the high dopant concentration of the added region. This added region also conducts electrons downward and expands the electrons to the bottom of the p+ shielding region. We discussed the influence of dopant concentration and the width of the added region on the breakdown voltage (BV) and the ON-resistance in this paper. A reasonable size and an optimized concentration were chosen for the added region in our simulation. The channel inversion layer mobility was set to 50 cm²/Vs, and the specific ON-resistance and the BVwere 1.64 mΩ·cm² (VGS = 15 V, VDS = 1 V, and no substrate resistance was included) and 891 V, respectively, using the numerical simulation.