Authors : Alias Mohd Saman, Tatsuaki Furumoto, Akira Hosokawa and Takashi Ueda
Abstract: This study investigates thermal-stress behavior during cleaving process of sapphire wafer by CO2 laser irradiation. Thermal-stress cleaving process is used to separate the sapphire wafer by extending the fracture via thermal stress generated by a laser heat. The process capable to produce an excellent separated surface condition. The finite-element method was used to evaluate a steady-state thermal stress by considering the temperature transient during irradiation process. Fracture initiation has been determined by analysing the stress intensity factor, K1. The result shows that energy from the CO2 laser was absorbed mostly on the surface area of the sapphire material. Thermal stress was generated and tensile stress developed at the bottom surface of the sapphire wafer. Fracture starts from the bottom surface of the material, instead of from the pre-prepared micro-groove on the irradiation surface if higher power laser is used. The fracture cannot be controlled and may lead to a poor cleaving surface. Therefore, laser absorption characteristics perform an important factor on fracture initiation in thermal-stress cleaving technique.
Alias Mohd Saman, Tatsuaki Furumoto, Akira Hosokawa and Takashi Ueda, 2017. Thermal Stress Analysis on Cleaving Sapphire Material by CO2 Laser. Journal of Engineering and Applied Sciences, 12: 3077-3082.