A snapback-free RC-IGBT with low reverse-conducting voltage drop

The reverse conducting insulated-gate bipolar transistor (RC-IGBT) suffers from snapback phenomenon that occurs in the initial stage of forward conduction. To avoid the such phenomenon, the RC-IGBT-thyristor (TRC-IGBT) structure is used. The TRC-IGBT utilizes a p-barrier layer above the n-collector to suppress the snapback. However, with the p-barrier layer, an anti-parallel thyristor is formed when the device reverse conducts, which can cause high reverse-conducting voltage V R . In this paper, a novel TRC-IGBT is proposed to suppress the snapback phenomenon while achieving a low V R . our structure features a highly-doped N-floating layer, which is partially embedded in the p-barrier layer. The N-floating layer injects electrons into the N-base and N-buffer layer, which forms a low-resistance path connecting the N-floating layer to the p-body/N-base junction. As a result, the gate voltage of the thyristor is pulled up, which turns on the anti-parallel thyristor and a low V R is achieved. By tuning the doping concentration and width of the n-floating layer, both the forward-conducting/reverse-conducting voltage trade-off and turnoff loss/forward-conducting voltage trade-off can be optimized. • Innovative Structure Design: A novel TRC-IGBT structure is proposed, featuring a highly-doped N-floating layer partially embedded within the P-barrier layer. • Snapback Elimination: The integrated P-barrier layer effectively suppresses the snapback phenomenon typically encountered during the initial stage of forward conduction in RC-IGBTs. • Reduced Reverse Voltage Drop: The N-floating layer facilitates electron injection and pulls up the thyristor gate voltage, significantly lowering the reverse-conducting voltage drop. • Optimized Performance Trade-offs: By tuning the N-floating layer parameters, the device achieves an improved trade-off between turn-off loss, forward voltage, and reverse voltage.