Novel Low Turn-Off Loss Trench-Gate FS-IGBT With a Hybrid $p^{{+}}/{n}$ Collector Structure

Abstract

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 ( ${V} _{\mathrm{ on}}$ ) and the turn-off energy loss ( ${E} _{\mathrm{ off}}$ ). 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 ${V} _{\mathrm{ on}}$ at 1.5 V, the HC-IGBT has an advantage in ${E} _{\mathrm{ off}}$ reduction by 69% and 22%, respectively. Finally, backside mask alignment is not needed for fabricating the proposed hybrid ${p} ^{+}/{n}$ collector structure.