RC-IGBT snapback suppression using silicon germanium collector regions

Abstract

In this study, two new structures are proposed for reverse-conducting insulated gate bipolar transistors (RC-IGBT) that effectively prevent snapback by relocating the N-collectors and utilizing silicon–germanium in the collector region of each device. The forward mode of the proposed structures shows I_C− V_C characteristics without snapback, since the position of the N-collector is changed to prevent electron extraction. In the reverse mode, the silicon–germanium induces currents through tunneling and impacts the ionization mechanisms. Importantly, the proposed structures generate a stable current value even if there are errors in the length of the N-collector during ion implantation, which enhances the reliability of the device. In addition, the proposed structures exhibit similar values for the breakdown voltage at around 700 V and the turn-on and turn-off losses when compared to the conventional RC-IGBT. Thus, this paper improves the reliability of RC-IGBTs by mitigating the snapback effect while maintaining their unique electrical properties.