Laser machining method and method for manufacturing compound semiconductor light-emitting element

摘要

Provided is a laser machining method in which, when modified regions are formed plural number of times by changing the depth in the thickness direction of a substrate, displacement of the formed modified regions from a planned cutting line is inhibited. Specifically provided is a laser machining method for cutting a substrate (10) into chips. Modified regions are formed at a deep distance (d1) inside the substrate from the entrance surface of a laser beam by first scanning (a) in which the substrate is scanned with the laser beam along a planned cutting line (21a) in the X direction of the substrate and second scanning (b) in which the substrate is scanned with the laser beam along a planned cutting line (21b) in the Y direction. Modified regions are again formed at a shallow distance (d2) (d1>d2) inside the substrate by third scanning (c) in which the substrate is scanned with the laser beam along the planned cutting line (21a) in the X direction and fourth scanning (d) in which the substrate is scanned with the laser beam along the planned cutting line (21b) in the Y direction. The third scanning is performed by scanning from a U end portion at the periphery to the center and scanning from a D end portion at the periphery to the center.

主权项

1. A laser machining method in which irradiation of a focused laser beam is applied to a plurality of distances from one surface of a substrate formed into a plate on the basis of a planned cutting line supposed to be set on the substrate so that modified regions at the plurality of distances are formed inside the substrate a plurality of times, comprising:
a first forming process in which, in the case where the modified regions are formed at a distance except the nearest distance with the one surface of the substrate, the modified regions are formed from one end portion of a periphery of the substrate toward an opposite end portion of the periphery of the substrate along the planned cutting line; and a second forming process that includes, in the case where the modified regions are formed at the nearest distance with the one surface of the substrate, a first machining method for forming the modified regions from the one end portion of the periphery of the substrate starting at a first end point towards a central portion of the substrate along the planned cutting line, and a second machining method for forming the modified regions from the opposite end portion of the periphery of the substrate starting at a second end point opposite the first end point toward the central portion of the substrate along the planned cutting line at least once in the plurality of times, wherein the second machining method is conducted after the first machining method.