Correlation between oxide breakdown and defects in SiC wafers

A correlation between gate oxide breakdown in metal oxide semiconductor (MOS) capacitor structures and structural defects in SiC wafers is reported. The oxide breakdown under high applied fields, in the accumulation regime of the MOS capacitor structure, is observed to occur at locations corresponding to the edge of bulk structural defects in the SiC wafer such as polytype inclusions, regions of crystallographic misorientation, or different doping concentration. Breakdown measurements on more than 50 different MOS structures did not indicate any failure of the oxide exactly above a micropipe. The scatter in the oxide breakdown field across a 10 mm × 10 mm square area was about 50%, and the highest breakdown field obtained was close to 8 MV/cm.