Patent ID: 8178425

Claim:
An optical device wafer processing method for dividing an optical device wafer into a plurality of individual optical devices, said optical device wafer being composed of a substrate and a semiconductor layer formed on the front side of said substrate, said optical devices being partitioned by a plurality of crossing division lines formed on said semiconductor layer, said optical device wafer processing method comprising: a division start point forming step of applying a laser beam having a transmission wavelength to said substrate to the intersections of said crossing division lines in the condition where the focal point of said laser beam is set inside said substrate in an area corresponding to the intersections of said crossing division lines, thereby forming a plurality of modified dots as division start points inside said substrate only at the intersections of said crossing division lines; and a crack growing step of applying a CO 2 laser beam along said division lines to grow cracks inside said substrate from said division start points.