Patent ID: 8138450
Filing Date: 2012-03-20
Classification: B23K,B28D,H01L

Abstract:
1. A method of cutting an object to be processed, the object comprising a substrate and a multilayer part provided on a front face of the substrate including a plurality of functional devices, the method comprising cutting the object along a each of a plurality of cutting lines arranged in a grid pattern including cutting lines extending in an x-axis direction and cutting lines extending in a y-axis direction, the method including the steps of: irradiating the substrate with laser light from a side of the substrate on which the multilayer part is provided while locating a converging point within the substrate, the side of the substrate on which the multilayer part is provided being a multilayer part side, so as to form a first modified region shifted from a center position in a thickness direction of the substrate toward a rear face side of the substrate opposing the multilayer part side and located within the substrate along each of the cutting lines; irradiating the substrate with the laser light from the multilayer part side while locating the converging point within the substrate, so as to form a second modified region shifted from the center position in the thickness direction of the substrate toward the multilayer part side of the substrate and located within the substrate along each of the cutting lines, and generating a fracture from the second modified region to the front face of the substrate; expanding an expandable member attached to the rear face of the substrate after forming the first and the second modified regions; during a state in which the expandable member is expanded, cutting the object into strips along the cutting lines extending in the x-axis direction by generating a stress in the object so as to open the fracture by pressing a pressing member against the rear face of the substrate with the expandable member interposed therebetween in orderly fashion along the cutting lines extending in the x-axis direction; and after cutting the object into strips, and during the state in which the expandable member is expanded, cutting the object into chips along the cutting lines extending in the y-axis direction by generating a stress in the object so as to open a fracture by pressing a pressing member against the rear face of the substrate with the expandable member interposed therebetween in orderly fashion along the cutting lines extending in the y-axis direction.