High voltage IGBT (HV-IGBT) having p/sup +//p/sup -/ collector region

For high voltage IGBTs (HV-IGBTs; rated collector voltage over 2.5 kV), it is very important that the thickness of the n/sup -/ layer (tn/sup -/) is thin to improve the trade-off relationship between collector-emitter saturation voltage (V/sub ce/(sat)) and turn-off switching loss (E/sub off/). A punch-through IGBT (PT-IGBT) with n/sup +/ buffer layer thus has a better trade-off than that of a nonpunch-through IGBT (NPT-IGBT) without the n/sup +/ buffer layer. However, the HV-IGBT with thin tn/sup -/ has much worse characteristics in that collector leakage current (I/sub CES/) is high and reverse bias safety operating area (RBSOA) is narrow. In order to solve these problems, we examined the collector region of a PT-IGBT. In this paper, we developed a HV-IGBT with a p/sup +//p/sup -/ collector region which has better characteristics in terms of the trade-off relationship between V/sub CE/(sat) and E/sub off/, and a wide RBSOA.