Complete Recovery of Subsurface Structures of Machining-Damaged Single Crystalline Silicon by Nd:YAG Laser Irradiation

Ultraprecision diamond-cut silicon wafers were irradiated by a nanosecond pulsed Nd:YAG laser, and the resulting specimens were characterized using transmission electron microscopy and micro-Raman spectroscopy. The results indicate that at specific laser energy density levels, machining-induced amorphous layers and dislocated layers were both reconstructed to a complete single-crystal structure identical to the bulk region. Similar effects were confirmed for diamond-ground silicon wafers. Effects of overlapping irradiation were investigated and perfect crystallographic uniformity was achieved in the boundary region. The recovery process involved rapid melting of the near-surface amorphous layer, followed by epitaxial regrowth from the damage-free crystalline bulk.