Laser recovery of machining damage under curved silicon surface

Nano-second pulsed laser irradiation was used to recover machining-induced damage under curved surfaces of single-crystal silicon. Microstructural changes of silicon due to laser irradiation were characterized by cross-sectional transmission electron microscopy and laser micro-Raman spectroscopy. The recoverable damage depth was predicted by finite element modeling of laser-induced temperature change in the workpiece material. Slanted irradiation experiments were performed and the critical surface inclination angle for complete recovery was experimentally obtained. The results demonstrate that atomic-level subsurface integrity and nanometric surface roughness can be achieved on large-curvature silicon surfaces, such as the surfaces of toroidally shaped wafer edges.