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Pulsed Nd:YAG laser cutting of silicon wafer by controlled fracture technique

During the laser cutting of brittle material using controlled fracture technique, thermal stress is used to induce the crack and the material is separated along the moving direction of the laser beam. In order to investigated the process of pulsed Nd:YAG laser thermal stress cutting brittle silicon wafer, a three-dimensional mathematical thermoelastic calculational model which contains a pre-existing crack was established. The temperature field and thermal stress field in the silicon wafer were obtained by using the finite element method. During the pulse duration, the changes of stress intensity factor around crack tip were analyzed. Meanwhile the mechanism of crack propagation was investigated by analyzing the development of the thermal stress field during the cleaving process, and the calculational results in this paper are in agreement with the reported experiment results.