Transient Performance of >10kV SiC IGBT with an Optimized Retrograde p-Well

Abstract

The impact of different p-well designs upon the transient performance, in particular, the turn-off losses and short-circuit capability, of a >10 kV SiC n-IGBT is assessed. We find that in addition to improved transient performance, a substantial reduction in the depth of p-well implants can be achieved, if an extensively optimized retrograde approach is utilized. A conventional p-well consisting of a uniformly doped deep implant (doping concentration of ~3×1017 cm-3 and depth of >1.5 µm) exhibits considerable turn-off switching losses without offering any short circuit capability. However, an optimized retrograde p-well consisting of a variable doping profile and depth as shallow as 0.7-0.8 µm results in much reduced turn-off losses with excellent short-circuit capability. Shallow implants are desirable to lower the development cost and processing challenges. The retrograde p-well is therefore highly promising for the development of >10 kV class of SiC IGBTs.