High voltage IGBT (HV-IGBT) having p+/p- 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^- layer (tn^-) is thin to improve the trade-off relationship between collector-emitter saturation voltage (V_ce(sat)) and turn-off switching loss (E_off). A punch-through IGBT (PT-IGBT) with n ⁺ buffer layer thus has a better trade-off than that of a nonpunch-through IGBT (NPT-IGBT) without the n⁺ buffer layer. However, the HV-IGBT with thin tn^- has much worse characteristics in that collector leakage current (I_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⁺/p^- collector region which has better characteristics in terms of the trade-off relationship between V_CE(sat) and E_off, and a wide RBSOA