| 摘要 |
An object to be processed is restrained from warping at the time of laser processing. A modified region M2 is formed within a wafer 11, and fractures a2, b2 extending in directions parallel to the thickness direction of the wafer 11 and tilted with respect to a plane including lines 5 are generated from the modified region M2. A modified region M3 is formed within the wafer 11, and a fracture a3 extending in a direction parallel to the thickness direction of the wafer 11 and tilted with respect to the plane including the lines 5 is generated from the modified region M3 so as to connect with the fracture b2. That is, the fractures a2, a3, b2 are generated so as to be connected together. Therefore, at the time of laser processing, the fractures cause both side parts holding the lines to cut 5 therebetween in the wafer 11 to mesh with each other, whereby internal stresses occurring in a direction parallel to the thickness direction of the wafer 11 and perpendicular to the surface including the lines 5 when the modified regions are formed can be reduced.
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