Impact of Threading Dislocations Detected by KOH Etching on 4H-SiC 650 V MOSFET Device Failure after Reliability Test

Abstract

In this study, the correlation between the Emission Microscopy (Em.Mi.) related to the failure site of the 4H-SiC 650V MOSFET devices after reliability test and epitaxial dislocation defects is presented. Devices failed at the High-Temperature Reverse Bias (HTRB) test were considered. Device layers have been stripped out by chemical wet etching and etched in a high temperature KOH solution to characterize defects emerging at the SiC surface. This approach was used to correlate failure emission spots with underlying structure of the material. KOH etching process on delayered devices was performed at 500°C for 10 minutes and then analysis by optical microscopy and SEM was carried out for defect classification and correlation with failure location.