A snapback suppressed reverse-conducting IGBT with soft reverse recovery characteristic

A reverse-conducting insulated-gate bipolar transistor (RC-IGBT) featuring floating P-region (P-float) embedded in the n-buffer layer is proposed. The P-float plays three roles at different working conditions. Firstly, it introduces a barrier in the n-buffer to obstruct the electron current from flowing directly to the n-collector at small current density, which achieved the hole emission from p-collector and suppressed the snapback effectively at forward conduction of IGBT mode. Secondly, the P-float will act as the base of the N-buffer/P-float/n-drift transistor which can be activated to extract the excessive carriers in turn-off process of IGBT mode. Finally, the P-float makes the proposed RC-IGBT work as the Controlled Injection of Backside Holes (CIBH) concept at reverse recovery of DIODE mode, which brings in soft factor S high up to 7.1. As the simulation results show, it achieves snapback-free output characteristics at small collector size (75 μm) and fast turn-off process of IGBT mode. On the other hand, the properties of DIODE mode are also superior to other structures.