6.5 kV SiC Power Devices with Improved Blocking Characteristics against Process Deviations

Edge termination structures that are insensitive to process deviations were investigated to obtain 6.5 kV SIC power devices with stable blocking characteristics. Edge terminations were designed and verified by a TCAD simulation in consideration of undesirable surface charge states and variation of the implantation window in the termination region. A constant-space floating guard ring (CS-FGR) was sensitive to the variation of the implantation window. A gradually increasing space (GIS) FGR was less sensitive to process deviations than the CS-FGR. We concluded that the GIS-FGR is sufficiently stable for use in high-voltage SiC devices at surface charge densities (Q(surf)/q) of 0 to -1 x 10(12) cm(-2) and implantation window variations of -0.3 to +0.3 mu m. The optimized GIS-FGR exhibited a high breakdown voltage of over 8 kV at all the Q(surf)/q valnes and in the implantation window variation range considered in this paper.