Patent ID: 8278592
Filing Date: 2012-10-02
Classification: B23K,B28D,C03B,H01L

Abstract:
1. A laser processing method of irradiating a planar object to be processed including a semiconductor substrate with laser light while using one face of the planar object as a laser light entrance surface, so as to form a plurality of rows of modified regions to become a cutting start point along a line to cut the planar object within the semiconductor substrate such that the modified regions align in a thickness direction of the planar object; the method comprising the steps of: irradiating the planar object with the laser light via the laser light entrance surface of the planar object; locating a converging point at a position within the semiconductor substrate; forming a weakened region having a predetermined depth along the line to cut simultaneously with a modified region closest to an opposite face of the planar object that is opposite to the one face of the planar object in the plurality of rows of modified regions; and forming a modified region other than the modified region closest to the opposite face in the plurality of rows of modified regions, wherein a portion of the light beams of the laser light that is pulse-oscillated while the converging point is located shifts to the optical axis direction of the laser light and converges, whereby the weakened region is formed as part of a dotted line along the line to cut, wherein the opposite face is a surface of a metal film in the object.