A Novel Low Turn-Off Loss and Snapback-Free Reverse-Conducting SOI-LIGBT With Integrated Polysilicon Diodes

Abstract

A novel reverse-conducting (RC) lateral insulated gate bipolar transistor based on the silicon-on-insulator (SOI-LIGBT) with integrated parallel/antiparallel polysilicon diodes ( $\text{D}_{F}$ and $\text{D}_{R}$ ) on the top of the anode active region is proposed and investigated by simulation. During the turn-off transient, the major part of the excess electron current flows through the parallel diode $\text{D}_{F}$ which achieves a low turn-off loss ( $E_{ \mathrm{\scriptscriptstyle OFF}}$ ). While during the forward-conducting state, the voltage across the p+-anode/n-buffer junction can rapidly increase to the junction’s built-in potential ( ${V}_{\text {bi}}$ ) at low anode current, which results in snapback immunity. Moreover, the antiparallel diode $\text{D}_{R}$ enables the proposed device to realize RC capability. Simulation results reveal that the proposed RC-LIGBT can realize superior $E_{ \mathrm{\scriptscriptstyle OFF}}$ - $V_{ \mathrm{\scriptscriptstyle ON}}$ tradeoff relationship than both the conventional LIGBT and the separated shorted-anode LIGBT (SSA-LIGBT). When $E_{ \mathrm{\scriptscriptstyle OFF}}$ is 0.44 mJ/cm2, $V_{ \mathrm{\scriptscriptstyle ON}}$ of the proposed RC-LIGBT is 1.95 V, which is 0.47 V lower than that of the SSA-LIGBT. Under ${V}_{ \mathrm{\scriptscriptstyle ON}}$ of 1.95 V, $E_{ \mathrm{\scriptscriptstyle OFF}}$ of the proposed RC-LIGBT is 0.44 mJ/cm2, which is reduced by 44.3% than that of the conventional LIGBT. Furthermore, the reverse recovery charge ( ${Q}_{\text {rr}}$ ) of the proposed device is reduced by 25.8% compared with that of the conventional one. In addition, diodes $\text{D}_{F}$ and $\text{D}_{R}$ and the thin oxide layer below can be fabricated during the implementation of the polysilicon gate. Therefore, there is no extra difficulty in the fabrication process of the proposed RC-LIGBT.