Alternated Trench-Gate IGBT for Low Loss and Suppressing Negative Gate Capacitance
Wataru Saito, Shin–ichi Nishizawa
Abstract
A new gate structure in the trench-gate insulated-gate bipolar transistor (IGBT) design is proposed and analyzed for power-loss reduction and the suppression of electromagnetic-interference (EMI) noise. Although the turn-off loss and the ON-state voltage drop Vce(sat) are improved by the injection-enhancement (IE) effect, the IE effect caused dynamic avalanche that limits the turn-off loss reduction. In addition, EMI noise is induced by high dI/dt and large surge current due to the negative gate capacitance. This article shows that the dynamic avalanche and the negative gate capacitance can be suppressed by the management of the electric field concentration and hole current flow around the trench gate by the proposed alternated trench-gate (AT) IGBT structure, and both low power loss and good switching controllability can be obtained. The device simulation results show that the AT-IGBT improves the turn-on surge current Isurge - Vce(sat) tradeoff compared with the conventional IGBTs.