Snapback‐free and low‐loss SAG‐LIGBT with self‐driving auxiliary gate

Abstract

A novel snapback-free and low-loss shorted-anode lateral insulated bipolar transistor (SA-LIGBT) based on silicon on insulator with self-driving auxiliary gate (SAG) in the anode is proposed, named as SAG-LIGBT. The SAG is characterised by metal oxide semiconductor (MOS) structure in the anode, and the gate of the MOS is shorted with the anode electrode, thus self-driving without extra gate signal is achieved. At anode voltage V A = 0, the P-base serving as a barrier to hinder electrons flowing into the N + anode. At V A = V on of the forward conduction, the P-base is depleted to intrinsic, and the anode resistance R SA is increased from R P-base to R intrinsic. At V A = V bus of the turn-off state, the P-base is fully depleted and an electron accumulation layer is formed under the SiO2, thus the R SA is decreased from R intrinsic to R n-channel to provide a low-resistance path for electron current. Consequently, the device not only eliminates the snapback effect but also reduces the turn-off energy loss E off. Therefore, a better trade-off is obtained between V on and E off. At the same V on, the E off of SAG-LIGBT is decreased by 57 and 66% compared with separated shorted-anode LIGBT (SSA-LIGBT) and SA-LIGBT, respectively. Moreover, the SAG-LIGBT exhibits the shorter T off of 80 ns than the SSA-LIGBT and vertical P-collector and N-buffer LIGBT at J A = 100 A/cm2.