Basal Plane Dislocations from Inclusions in 4H-SiC Epitaxy

Suppression of basal plane dislocations (BPDs) from critical epitaxial drift layer has occurred mainly by converting BPDs in the substrate into threading edge dislocations before the BPDs enter the drift layer. As optimized epitaxial growth has produced drift layers free of BPDs originating from the substrate over a large fraction of the wafer, other sources of BPDs have become important. One source of BPDs introduced during epitaxial growth is from inclusions, which mainly consist of misoriented 4H-SiC. Inclusions are surrounded by a local cluster of BPDs and in thick, low-BPD epitaxy the outermost BPDs glide centimeters from the inclusion forming a much larger damaged area. The details of BPD migration from inclusions are discussed.