Patent ID: 7939430

Claim:
A laser processing method of cutting an object to be processed along a cutting line, the object comprising a substrate and a multilayer part formed on a front face of the substrate, the multilayer part including a functional device positioned adjacent to and along the cutting line, the method comprising the steps of: attaching a protective member to a front face of the multilayer part; irradiating the substrate with laser light through a rear face of the substrate comprising a laser light entrance surface and locating a converging point of the laser light within the substrate in order to form a modified region within the substrate which serves as a starting point region for cutting the substrate along the cutting line, thereby generating a fracture reaching at least the front face of the substrate from an end part of the modified region located closest to the front face of the substrate, without generating any fracture reaching the rear face of the substrate from the modified region; attaching an expandable member to the rear face of the substrate that no fracture has reached after generating the fracture; and cutting the object along the cutting line by expanding the expandable member after attaching the expandable member to the rear face of the substrate.