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 (VA), 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SA</sub> ) act as a SAR. It not only eliminates the snapback effect but also reduces on-state voltage drop (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ) and turn-off energy loss (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ). Therefore, SAR LIGBT achieves a better tradeoff between VON and EOFF. At the same VON, the SAR LIGBT reduces the E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> of 1.71 V and the shortest switching time of 93 ns at J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</sub> = 100 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In addition, the SAR LIGBT achieves snapback-free with smaller cell pitch than that of separated SA LIGBT.