Healing defects in SiC wafers by liquid-phase epitaxy in Si melts

Silicon carbide epitaxial layers were grown by liquid-phase epitaxy on 6H-SiC-modified Lely crystals containing a high density of micropipes (MP) and other defects. The geometrical configuration of the seed crystals inside the crucible during LPE was such that the epitaxial layer growth occurred simultaneously on both the faces of the seed crystals. Layers in the range of 20-30μm thickness were deposited on both the faces of the crystals. X-ray diffraction, optical and scanning electron microscopy analyses were carried out to investigate these layers. It was found that dislocation and MP density in the substrate after LPE growth has been significantly reduced. Several MP were observed to decompose into non-hollow core dislocations. The growth centre associated with MP reduces in size in general and shifts to new centres due to the decomposition of the MP. As a result these new centres dominate the growing surfaces in LPE and make the healed MP completely invisible.