On-state and short circuit behaviour of high voltage trench gate IGBTs in comparison with planar IGBTs

The impact of the cathode geometry on conduction and switching properties of high voltage trench gate IGBTs is analysed using mixed mode two-dimensional device and circuit simulation tools. The most effective means to minimize conduction losses by injection enhancement at the cathode is the reduction of the width of the mesa containing n ⁺ electron emitters and the MOS channel regions. As compared to planar IGBTs, the improvement is most pronounced at higher operating temperatures. If low short circuit current densities are of concern, optimized trench gate geometries also require wide trenches. Trading off conduction losses against turn-off losses, trench gate IGBTs generate approximately 30 to 40% less turn-off losses as planar IGBTs with identical on-state voltage