A microscopic TEM study of the defect layers in cast-mono crystalline silicon wafers induced by diamond-wire sawing

Slicing silicon ingots into wafers by diamond-wire sawing (DWS) is an important step in the material production chain in the semiconductor industry. It will induce defect layers that are highly related to the stress release process and further influence wafers’ mechanical properties. This work aims to investigate the stress release in brittle crystalline silicon via the behaviors of defect layers comprising a surface phase transformed layer and a subsurface crystalline defect layer in DWS silicon wafers from the microscopic perspective. The micro-characteristics of defect layers were mainly obtained by transmission electron microscopy (TEM). The grooves’ surface contains amorphous silicon (a-Si) and diamond-cubic silicon (dc-Si), whereas indentations also contain additional Si-III and Si-XII phases, which were confirmed by both characteristic Raman peaks and the diffraction spots in the TEM image. The subsurface crystalline defect layers were characterized with a similar depth distribution of ∼0.6 µm and possess high-density planar-like defects, which were confirmed as novel defects with a large number (typically 200–400) of compactly strung-together nano-stacking faults inside and believed to be more favorable for stress release. Results show that the stress in crystal silicon can be well relaxed via plastic ways. These findings provide in-depth insights for revealing the essential characteristics of the defect layers in DWS wafers and will be beneficial for the understanding of the plastically deformed mechanisms of brittle silicon crystals.