Debris-Free Laser-Assisted Low-Stress Dicing for Multi-Layered MEMS

—Separation Method of Glass Layer—

Abstract

We have investigated the novel debris-free in-air laser dicing technology for glass. The target wafer was a soda lime glass and a Pyrex glass with the thickness of 1 mm. Our technology combines two processes, which was a dicing guide fabrication and a wafer separation process. First process was the internal transformation using a fundamental wavelength of a Ti:Sapphire laser or a Nd:YAG laser. The pulse width of each laser was 100 fs and 10 ns. The threshold energy for the internal transformation (NA-0.7 focusing) was 3 μJ and 65 μJ, respectively. The second process was a thermally-induced crack propagation using CO₂ laser or a mechanical bending separation by pressing a blade. The internal transformation fabricated in first process worked sufficiently as the guide of separation, the dicing line completely followed the internal transformation. The diced cross-section was sharp and free from chipping. In addition, neither debris nor damages were found on the surface after laser dicing.