Experimental and numerical analysis of crack-free DPSS laser dicing of borosilicate glass
Résumé
We demonstrate the possibility of the crack-free laser dicing of borosilicate glass. The effect of a polymer layer is analyzed on the laser (diode-pumped solid-state, 355 nm, nanosecond) dicing capability of a commercial glass (Borofloat®33) for backend packaging. The main drawbacks concerned the brittleness of glass and photothermal ablation which induces thermal stresses responsible for chipping or cracks. It was assumed that a thick enough polymer would enhance the energy coupling between the beam and the target. The effect of pulse energy and speed on the scribing depth is provided in the present article. A numerical simulation using COMSOL® Multiphysics was performed in order to analyze the volume temperature distribution. It revealed that the temperature remained higher than the working point of glass (1,500 K) between two pulses. The viscosity is thus low between two pulses, and thermal stresses are diminished compared to the processing of raw glass samples.