A Novel Trench IGBT With N-P-N Polysilicon Gate Structure for Low EMI Noise and High Robustness

In this article, an innovative 1200 V insulated gate bipolar transistor (IGBT) is proposed with N-P-N three polysilicon layers staked gate (PG) structure. This novel gate structure can be feasibly manufactured, which is constituted by two polysilicon diodes (PDs) connected in common anode. Then, the inventive charging mechanism of the PG structure at blocking state provides higher breakdown voltage (BV) due to the lateral electrical field by the \text{N}^{-} polysilicon depleted region. While the PD2 depleted region contributes to reducing the Miller capacitance ( {C}_{\text {res}}{)} and charging up the trench bottom potential higher before turn on process, it weakens the hole carrier accumulation and further suppresses the displacement current to the gate during the turn on period. Investigated by the TCAD tools, the proposed IGBT shows 16.9% reduced {C}_{\text {res}} and better {E}_{\text {off}} - {V}_{\text {CEon}} tradeoff (17.3%) compared with the conventional IGBT. Besides that, the proposed IGBT also indicates 49.0% decline on the surge current and 63.4% decline on the \textit {dV}_{\text {KA}}/\textit {dt}_{\text {max}} of the free-wheeling diode (FWD) for 30 mJ turn on energy loss ( {E}_{\text {on}}{)} compared with the conventional IGBT, which demonstrates lower Electromagnetic interference (EMI) noise. Finally, the proposed IGBT features wider borders of the RBSOA and SCSOA, which guarantees the robustness of this novel gate structure.