A Snapback-Free Fast-Switching SOI LIGBT With Polysilicon Regulative Resistance and Trench Cathode

A snapback-free fast-switching lateral insulated-gate bipolar transistor (LIGBT) with low power loss and high ruggedness is proposed and investigated by simulation. The proposed device features a polysilicon regulative resistance (PR) and a trench cathode (TC), named PRTC LIGBT. The PR is employed to not only suppress the snapback effect by regulating the voltage drop between P+ anode and N-buffer, but also improve the tradeoff between the on-state voltage drop ( $\text{V}_{ \mathrm{\scriptscriptstyle ON}})$ and turn-off loss ( $\text{E}_{ \mathrm{\scriptscriptstyle OFF}})$ . The TC widens the hole current path and decreases the distributed resistance under N+ cathode, and thus delivers a high latch-up ruggedness. Additionally, the PRTC LIGBT exhibits a blocking characteristic irrelevant to P+ anode concentration (N A ), like a p-i-n diode (P-well, N-drift, and N-buffer), owing to its undepleted N-buffer region. Simulation results show that the PRTC LIGBT eliminates the snapback and reduces the $\text{E}_{ \mathrm{\scriptscriptstyle OFF}}$ by 28% compared to the segmented trenches in the anode (STA) region LIGBT. Its short-circuit time is prolonged by 53% and 40% compared to those of the STA LIGBT and PR LIGBT (without TC), respectively.