A split-gate trench IGBT with low Miller capacitance and dV/dt noise

Abstract

A novel trench insulated gate bipolar transistor (IGBT) with a split-gate structure is proposed herein, where the polysilicon electrode in the trench is divided into two parts and insulated by the polysilicon oxide, thus decreasing the overlap between the gate electrode and n-drift region. Due to this split-gate structure, much lower Miller capacitance can be achieved. The performance of the proposed split-gate IGBT device, in particular the turn-on dV/dt controllability, is discussed. The simulation results show that the proposed split-gate IGBT can achieve a much better tradeoff between the maximum reverse-recovery dVKA/dt of the free-wheeling diode and the turn-on loss (Eon) of the IGBT compared with the conventional IGBT design. The reverse-recovery dVKA/dt can be decreased by 56% at the same Eon as in the IGBT. Moreover, a feasible manufacturing process for the split-gate structure is proposed.