Patent ID: 8247734
Filing Date: 2012-08-21
Classification: A61M,B23K,B28D

Abstract:
1. A laser processing method comprising the steps of: irradiating a wafer-like object to be processed which has a front surface and a rear surface and which is secured to a surface of an expandable holding member with pulsed laser light from a laser light source while focusing a light-converging point within the object, so as to form a modified region only within the object, wherein the modified region forms a cutting start region inside of a laser light entrance surface of the object by a predetermined distance along a line along which the object is to be cut, and wherein any fractures generated from the modified region formed in the step of irradiating the wafer-like object with pulsed laser light do not reach either the front surface or the rear surface of the wafer-like object; irradiating the modified region with pulsed laser light from the laser light source transmittable through an unmodified region of the object and more absorbable by the modified region than by the unmodified region after the step of forming the cutting start region, so as to change the cutting start region into one from which it is easier to generate a fracture compared to the cutting start region as configured prior to the step of irradiating the modified region, and cutting the object along the line along which the object is to be cut by causing fractures generated from the modified region to extend from the modified region to the front surface and the rear surface of the wafer-like object; and expanding the holding member after the step of cutting the object, so as to separate cut portions of the object from each other.