CONTROLLER FOR FORMATION OF STARTING POINT REGION FOR CUTTING

摘要

PROBLEM TO BE SOLVED: To provide a controller for formation of a starting point region for cutting that can thin and divide a substrate while preventing chipping and cracking from occurring.SOLUTION: The controller for formation of starting point region for cutting includes: a means of setting relative positions of a condensing position P of a laser light source 101 and a mounting table 107 for the substrate 1 in a substrate thickness direction so that the condensing point P of irradiating laser light is a predetermined position in the substrate 1; a means of relatively moving the laser light source 101 and mounting table 107 along lattice-shaped predetermined cutting lines 5 while keeping the set positions in the substrate thickness direction; and a means of irradiating the substrate 1 with the laser light with a peak power density of ≥1×10W/cmat the condensing point P so as to form a modified region at a substrate inside position shifting from the center position of the substrate in the thickness direction toward a laser light irradiated surface of the substrate 1, so that a crack including the modified region as a cutting starting point region reaches the laser light irradiated surface of the substrate, but does not reach the opposite-side surface of the substrate.