Mask-edge defects in hybrid orientation direct-Si-bonded substrates recrystallized by solid phase epitaxy after patterned amorphization

Solid phase epitaxy (SPE) of patterned amorphized Si regions in direct-Si-bonded (DSB) hybrid orientation substrates is complicated by the fact that the amorphized Si regions being recrystallized have sides and bases formed from different Si crystals. In DSB wafers with a Si (011) DSB layer on a Si (001) handle wafer, the competition between lateral and vertical SPE produces distinctively angled mask-edge defects and recrystallization fronts. Some mask edges exhibit triangular bands of defective Si bounded by DSB and handle wafer {111} planes meeting at 90° angles, while other mask edges are relatively defect free, but can have downward-pointing facets of Si (011) growing below the DSB interface. A simple model recently developed to explain trench-edge defect formation and faceted recrystallization in bulk single-orientation Si appears to explain all of these observations.