Laser Bending of Silicon Sheet: Absorption Factor and Mechanisms

摘要

Laser bending of silicon sheet is a process to form three-dimensional microstructural silicon elements in an ambient environment. This study aims to investigate the process mechanism with the aid of both experimental and numerical analyses. To this end, a thin-film thermocouple was prepared to capture the temperature field within the heating zone of the laser beam. A new method was then developed to precisely determine the absorption factor by coupling numerical simulation of the laser bending results with the experimental results. It was found that each laser pulse causes a cycle of sharp temperature rise-drop in a silicon sheet. When the temperature in the heating zone is low, the sheet deforms elastically. When it is beyond the brittle-ductile transition temperature of silicon, however, plastic deformation in the sheet takes place and bending occurs. The bending angle becomes larger with increasing the number of laser beam scanning, once the temperature gradient in the scanning area is large enough.