A Snapback-Free and Low-Loss Shorted-Anode SOI LIGBT With Self-Adaptive Resistance

Abstract

A novel 600-V snapback-free and low-loss shorted-anode (SA) silicon on insulator lateral insulated gate bipolar transistor (LIGBT) with self-adaptive resistance (SAR) in anode is proposed and investigated by simulation, named SAR LIGBT. The device is characterized by dual anode trenches which are filled with p-type polysilicon and surrounded by oxide, and the dual trenches are shorted with the anode electrode, separated by the low-doped N− region and N+ anode region. At low anode voltage ( $V_{A}$ ), the N− region is fully depleted by p-type polysilicon, serving as a large resistance to hinder electrons flowing into the N+ anode; at high VA, an electron accumulation layer is formed along the anode trenches to provide a low-resistance path for electron current. Consequently, N− region makes the distributed resistances at the anode side ( ${R}_{\text {SA}}$ ) act as a SAR. It not only eliminates the snapback effect but also reduces on-state voltage drop ( ${V}_{ \mathrm{\scriptscriptstyle ON}}$ ) and turn-off energy loss ( ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ ). Therefore, SAR LIGBT achieves a better tradeoff between $V_{ \mathrm{\scriptscriptstyle ON}}$ and ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ . At the same ${V}_{ \mathrm{\scriptscriptstyle ON}}$ , the SAR LIGBT reduces the ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ by 20.6%, 28.1%, and 30.5% compared with those of multisegment anode, segmented trenches in the anode, and SA-NPN LIGBTs, respectively. Moreover, the SAR LIGBT exhibits the lowest ${V}_{ \mathrm{\scriptscriptstyle ON}}$ of 1.71 V and the shortest switching time of 93 ns at $J_{A} = {100}$ A/cm2. In addition, the SAR LIGBT achieves snapback-free with smaller cell pitch than that of separated SA LIGBT.