Complete Restoration of the Subsurface Damages in Single-Crystalline Silicon by Laser Irradiation

Abstract

Ultraprecision diamond-machined silicon wafers have been irradiated by a nanosecond pulsed Nd:YAG laser. The results indicate that at specific laser energy intensity levels, the machining-induced subsurface damage layer of silicon has been reconstructed to a perfect single crystalline structure identical to the bulk. Laser irradiation causes two effects to silicon: one is the rapid melting and epitaxial regrowth of the near-surface amorphous layer; the other is the activation and complete removal of the dislocations from the crystalline layer. It is the dislocation-free crystalline bulk region that serves as the seed layer to recrystallize the amorphous layer, enabling excellent crystalline perfection. These findings may offer practical alternatives to current chemo-mechanical processing methods for silicon wafers.