Improving dynamic performance for split-gate trench power MOSFETs using variable vertical doping profile

In this paper, a split-gate trench power MOSFET (SGT) with a variable vertical doped (VVD) drift region is proposed. The VVD SGT MOSFET features ultra-low gate-drain charge ( Q GD ) and low switching losses. Due to the introduction of variable vertical doping, the concentration of the drift region near the source is relatively low. The depletion layer outside the trench of the new structure widens towards the drain during depletion spreading, effectively reducing the depletion layer capacitance and thus greatly reducing the gate-drain capacitance ( C GD ). The significant reduction of Q GD and total switching losses is confirmed by simulation. Compared with the conventional split-gate trench MOSFET, the dynamic figure of merit R ON × Q GD = 22.60 mΩ nC and turn-off loss of the proposed VVD SGT MOSFET are reduced by 42% and 37%, respectively. Moreover, the proposed structure also demonstrates an improvement in the reverse recovery performance. • A split-gate trench power MOSFET (SGT) with a variable vertical doped (VVD) drift region is proposed. • The proposed device structure achieves a significant improvement in the tradeoff relationship between R ON and Q GD. • The various performance indicators of the proposed device are proposed and studied by using TCAD tools.