Snapback-free reverse conducting IGBT with p-poly trench-collectors

A reverse conducting (RC) insulated-gate bipolar transistor (IGBT) with p-poly trench-collectors is proposed. A narrow n-drift region between two p-poly trench-collectors is formed as a self-controlled electron path to the collector contact. Owing to the built-in potential between the p-poly and n-drift regions, the narrow n-drift region is depleted to offer a high-resistance electron path at forward bias, which helps to suppress snapback. At reverse bias, holes accumulate at the n-drift/trench-collector interface and then the potential difference between the p-poly and n-drift regions mainly drops at the thin oxide layer. Thus, the narrow n-drift becomes undepleted to offer a low-resistance electron path, and the RC diode can be turned on. Simulation results show that the proposed RC-IGBT is able to suppress snapback with a much smaller cell width and obtain a 21% lower turn-off loss compared to the conventional RC-IGBT.