| 摘要 |
A laser processing method is provided, which, even when a substrate formed with a laminate part including a plurality of functional devices is thick, can cut the substrate and laminate part with a high precision. This laser processing method irradiates a substrate 4 with laser light L while using a rear face 21 as a laser light entrance surface and locating a light-converging point P within the substrate 4, so as to form modified regions 71, 72, 73 within the substrate 4. Here, the HC modified region 73 is formed at a position between the segmented modified region 72 closest to the rear face 21 and the rear face 21, so as to generate a fracture 24 extending along a line to cut from the HC modified region 73 to the rear face 21. Therefore, when an expandable tape is bonded to the rear face 21 of the substrate 4 and expanded, fractures smoothly advance from the substrate 4 to a laminate part 16 by way of the segmented modified regions 72, whereby the substrate 4 and laminate part 16 can be cut along the line to cut with a high precision.
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