| 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 quality modified region 71 is formed at a position where the distance between the front face 3 of the substrate 4 and the end part of the quality modified region 71 on the front face side is 5 mum to 15 mum. When the quality modified region 71 is formed at such a position, a laminate part 16 (constituted by interlayer insulating films 17 a , 17 b here) formed on the front face 3 of the substrate 4 is also cut along a line to cut with a high precision together with the substrate 4.
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