Defects in 4H-SiC epilayers affecting device yield and reliability.

Forty nine silicon carbide 150 mm wafers from three commercial vendors to be used for fabricating MOSFETs were examined by UVPL imaging to count their concentration of basal plane dislocations, inclusions, micropipes and trapezoids. The wafers were from three vendors, and wafers with 10 um, 30 um and 60 um epitaxial layers were evaluated. The wafers with 10 um and 30 um epilayers were virtually free of BPDs, while BPD concentrations of the wafers with 60 um were too high for commercial use. Concentrations of inclusions, micropipes and trapezoids were also evaluated. Most of the wafers had acceptable levels of these defects, but device yield would be improved by more consistently having low concentrations.