Turn-Off Transient of Superjunction SOI Lateral IGBTs: Mechanism and Optimization Strategy

Abstract

In this paper, five types of superjunction (SJ) configurations are investigated in the silicon-on-insulator lateral insulated-gate bipolar transistor (SOI-LIGBT). technology computer aided design simulations are carried out to give insight into the mechanism for improving turn-off loss ( ${E} _{ \mathrm{\scriptscriptstyle OFF}}$ ) by adopting SJ in the drift region of SOI-LIGBT. In mechanism revealing, collector–emitter voltage rising during the inductive load turn-off is divided into two phases: slow rising phase (SRP) and rapid rising phase (RRP). It is found that the depletion accompanying with carrier extraction in the drift region and at the collector is responsible for the SRP and RRP, respectively, and accordingly, the difference of turn-off transient among the five types of SJ configurations is clarified. Moreover, reduced ${E} _{ \mathrm{\scriptscriptstyle OFF}}$ can be realized by lowering the transition voltage from SRP to RRP ( ${V} _{\text {A}}$ ). Low electric potential from the emitter side can be delivered to the collector side through the undepleted regions in P-pillar, which largely determine ${V} _{\text {A}}$ . According to the above-mentioned mechanism, an optimization strategy and a novel SJ SOI-LIGBT with composite P-pillar are proposed for the first time. The proposed SJ SOI-LIGBT achieves an ${E} _{ \mathrm{\scriptscriptstyle OFF}}~76.3$ % lower than the conventional SOI-LIGBT at ON-state voltage drop of ~1.41 V.