Novel Low Turn-Off Loss Trench-Gate FS-IGBT with a Hybrid p⁺/n Collector Structure

A trench-gate field stop insulated gate bipolar transistor (TFS-IGBT) with a novel hybrid p⁺/n collector structure is proposed to enhance the trade-off relationship between the on-state voltage drop (V_on) and the turn-off energy loss (E_off). The proposed hybrid collector structure consists of a p+/n layer between the p⁺ collector and the field stop layer. During turn-on, the p⁺ regions in the hybrid p⁺/n layer provide high carrier injection efficiency. During turn-off transient, the n-regions in the hybrid p⁺/n collector provide fast carrier extraction paths for holes. 2-D numerical simulations comparing a conventional TFS-IGBT, an injection efficiency controlled IGBT with the proposed hybrid p⁺/n collector TFS-IGBT (HC-IGBT) having similar device structures show that for a 1.2 kV rating and with V_on at 1.5 V, the HC-IGBT has an advantage in E_off reduction by 69% and 22%, respectively. Finally, backside mask alignment is not needed for fabricating the proposed hybrid p⁺/n collector structure.