Nucleation of Dislocations from Scratches on the Surface of PVT-Grown 4H-SiC Wafers

Dislocation generation mechanisms from surface damage formed at post-substrate processing are investigated by synchrotron monochromatic beam x-ray topography (SMBXT) for physical vapor transport (PVT)-grown 4H-type silicon carbide (4H-SiC) commercial wafers. Three types of dislocation generation mechanisms are identified: type 1: basal plane dislocation (BPD) loop expansion; type 2: prismatic slip of threading edge dislocations (TEDs) nucleated around scratches; type 3: partial dislocation (PD) loop expansion. For the first time, two PDs dissociated from one BPD generated from scratches are observed to expand to the same side of scratches with a single Shockley stacking fault region between them. The relation between orientation of scratches and shape of PD loops is discussed. The results suggest that a proper surface preparation procedure is essential to minimize inadvertent defect nucleation in 4H-SiC substrates.