Patent ID: 8735771
Filing Date: 2014-05-27
Classification: B23K,B28D,C03B,C03C,H01L

Abstract:
1. A laser processing method for forming a modified region inside a plate-like object along a cutting line, the modified region serving as a mechanically weakened area inside the plate-like object for cutting, the plate-like object including an effective part that is to be cut, and an outer peripheral part surrounding the effective part, the cutting line having a first end portion, an intermediate portion, and a second end portion, the intermediate portion covering the effective part, the method comprising: (i) continuously oscillating the laser light while moving a light-converging point of a laser light along the first end portion, thereby avoiding formation of the modified region at the first end portion of the cutting line; (ii) pulse oscillating the laser light while moving the light-converging point of the laser light along the intermediate portion so that the intensity of the light-converging point of the laser light is such that the modified region is formed continuously at the intermediate portion of the cutting line; and (iii) continuously oscillating the laser light while moving the light-converging point of the laser light along the second end portion, thereby avoiding formation of the modified region at the second end portion of the cutting line; wherein steps (i), (ii), and (iii) are performed such that while the light-converging point is moved along the first end portion, the intermediate portion, and the second end portion of the cutting line, the laser light is switched from continuous oscillation to pulse oscillation at a transition from the first end portion to the intermediate portion, and is switched from pulse oscillation to continuous oscillation at a transition from the intermediate portion to the second end portion.