Buried field rings - a novel edge termination method for 4H-SiC high voltage devices

This paper is concerned with a numerical study of a novel edge breakdown termination technique for 4H-SiC high voltage devices. Buried field rings (BFRs) are proposed to be used, for the first time, in SiC devices as an effective termination method and the concept is numerically demonstrated for 4H-SiC MESA JFET structures. By using 4 BFRs for a MESA JFET, a breakdown voltage of 1,590 V has been achieved, representing more than 90% of the ideal bulk breakdown value (1,750 V). The influence of the buried rings doping on the blocking mode behaviour and the effect of the SiC/SiO₂ interface charge on the breakdown voltage are studied. It is evidenced that the BFR termination offers a very stable blocking mode behaviour and the influence of processing conditions on its over-all performance is negligible. For comparison, some results for guard rings and junction termination extension are also presented.