Ultrafast laser processing and metrology for consumer applications

High-intensity, blue LEDs have attracted interest because of their wide applications. Dicing method using tightly focused ultra-fast laser beam inside the sapphire substrate is one of the remarkable processing method in terms of high yield and LED performance. In this paper, we would like to introduce the polarization controlled laser processing technique in which laser beam is focused tightly inside the sapphire substrate. The morphology of a cut line can be controlled by changing the direction of laser polarization to an orientation flat of the substrate. We, moreover, found that the crack inside the sapphire substrate can be elongated by using the double pulse train for 20 % larger than the single pulse when the pulse interval was 20 nsec. The crack was fabricated effectively by shorter pulse interval.