トレンチゲートFS-IGBTのターンオン特性に与えるフローティングpベースの影響 Influence of Floating P-Base on Turn-On Characteristics of Trench-Gate FS-IGBT

During the turn-on period of IGBTs under inductive load switching, a collector voltage waveform characterized by medium-voltage hump followed by a long tail is usually observed. Further, this waveform indicates a large turn-on dissipation and is significant in the case of trench-gate FS-IGBTs designed on the basis of the wide-cell-pitch concept with floating p-base. In order to understand the lossy waveform, the transient behavior of the floating p-base in the wide-cell-pitch trench gate FS-IGBT is analyzed quantitatively. The transient behavior corresponding to the long tail has been interpreted well on the basis of the unintentional operations of a parasitic p-channel MOSFET and/or pnp transistor.