Effects of defects in a 4H-SiC material on the breakdown behavior of a Schottky barrier diode

Abstract

This study investigated the relationship between the failure of a silicon carbide (SiC) Schottky barrier diode (SBD) and the corresponding defects on its 4H-SiC substrate and epitaxial layer. The dislocations enlarged by KOH etching and other surface defects of SiC materials were characterized by SICA88, and the linking function of which was used to track the same locations on the 6 inches wafer. This paper statistically showed the type of defect that leads to dead dies that are featured with breakdown points. Results show that 88% of breakdown points on the device were strongly related to single threading screw dislocations (TSDs), or TSD related defects in the substrate. In addition, 77% of the breakdown points would correspond to small pits on the epitaxial layer, that originate from substrate TSDs. In conclusion, substrate TSDs, which inherit and produce pits on the epitaxial surface, have a higher probability to cause SiC SBD breakdowns. Possible reasons for how a TSD can extend and develop into a pit on the epitaxial layer were proposed.