Lab-Based X-Ray Topography Characterization of Axial Samples from 4H-SiC Boules Grown by PVT Method

Axial sliced samples from 4H-SiC boules grown by PVT method were characterized by lab-based X-ray topography systems. Valuable information about dislocation behaviors during crystal growth was revealed. TSD/TMD propagation during PVT growth was studied. The different TSD/TMD propagation directions inside and outside the facet region were identified as the direct cause of the reduced TSD/TMD density at the facet boundary on some c-plane wafers. A defect reduction mechanism was proposed based on this discovery. It was observed that TSDs/TMDs were emitted by a void structure formed during crystal growth, which explained the elevated TSD/TMD density in the center regions of some wafers. The formation mechanism of such defect is different from the previous studies and remains under investigation.