A Snapback Suppressed Reverse Conducting IGBT with Oxide Trench Collector

A novel reverse conducting insulated-gate bipolar transistor (RC-IGBT) is proposed and investigated by numerical simulations. This new device features an oxide trench inserted between the N-collector and the P-collector. The oxide trench increases the collector short resistance by cutting off the low resistance electron path which is formed by the N-buffer layer. The snapback effect is therefore suppressed. Furthermore, the collector short resistance can be adjusted by varying the depth of oxide trench without dramatically increasing the collector cell dimension. As simulation results show, the snapback can be completely eliminated with 240-μm-length collector cell and integrated free-wheeling diode (FWD) with about 0.8-V on-state voltage at collector current density of 100 A/cm². It is worth to point out that the new structure makes the P-collector/N-buffer junction current relatively uniform, which is favorable to the device reliability.