Workpiece cutting method

摘要

Fractures (17a, 17b) are generated from modified regions (7a, 7b) to front and rear faces (12a, 12b) of a object to be processed (1), respectively, while an unmodified region (2) is interposed between the modified regions (7a, 7b). This can prevent fractures from continuously advancing in the thickness direction of a silicon substrate (12) when forming a plurality of rows of modified regions (7). By generating a stress in the object (1), the fractures (17a, 17b) are connected to each other in the unmodified region (2), so as to cut the object (1). This can prevent fractures from meandering in the rear face (12b) of the object (1) and so forth, whereby the object (1) can be cut accurately along a line to cut the object (5).

主权项

1. A method of cutting an object to be processed, the method of irradiating a sheet-like object to be processed equipped with a silicon substrate with a laser light so as to form a modified region in the silicon substrate along a line to cut the object and cutting the object along the line from the modified region acting as a cutting start point, the method comprising the steps of:
forming a first modified region as the modified region so as to generate a first fracture from the first modified region to one main face of the object along the line, and a second modified region as the modified region on the other main face side of the first modified region such that an unmodified region is interposed between the first and second modified regions so as to generate a second fracture from the second modified region to the other main face along the line without connecting the second fracture to the first fracture in the unmodified region; and generating a stress in the object so as to connect the first and second fractures to each other and cut the object along the line, wherein the first and second modified regions are formed such that, in a pair of cut surfaces of the object cut along the line, the unmodified region in one cut surface is formed with a projection extending in a direction intersecting the thickness direction of the silicon substrate, while the unmodified region in the other cut surface is formed with a depression corresponding to the projection; and wherein the projection has a height of 2 μm to 6 μm and a width of 6 μm to 17 μm in the thickness direction of the silicon substrate.