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

For high voltage IGBTs(HV-IGBTs; Rated collector voltage over 2.5kV), it is very important that thickness of n(-) layer (tn(-) is thin to improve the trade-off relation between collector-emitter saturation voltage(V-CE(sat)) and turn-off switching loss(Eoff). So, Punch through IGBT(PT-IGBT) with n(+) buffer layer has better trade-off than that of Non punch through IGBT(TPT-IGBT) without n(+) buffer layer.[l][2] However, HV-IGBT of thin tn(-) has such worse characteristics that collector leakage current (I,) is high and reverse bias safety operating area(RBSOA) is narrow. To solve these problems, we took notice of a collector region of PT-IGBT. In this paper, we developed HV-IGBT having p(+)p(-) collector region which has better characteristics of the trade-off relation between V-CE(sat) and Eoff, and wide RBSOA.