Laser processing method

A laser processing method comprising a laser light emitting step of emitting a pulsed laser light along a line from a back surface of a target comprising a substrate, wherein

• the laser light emitting step includes:
• a first step of irradiating a functional element layer of the substrate that is made of a different material from the rest of the substrate and defines a front surface of the substrate with a first pulsed laser light along the line in a first focusing position located proximal to the front surface, to form a weakened material region in the functional element layer along the line by embrittling the material without removing the material;
• and
• a second step of emitting a second pulsed laser light into the substrate of the target to follow the first pulsed laser light along the line in a second focusing position located between the first focusing position and the back surface, wherein
• (i) the emitted second pulsed laser light causes formation of a crack that begins in a first intermediate portion of the substrate located at a depth between the front surface and the back surface of the substrate as defined by the second focusing position,
• (ii) the crack extends in a first direction to reach the front surface and also extends in a second direction different from the first direction to reach a second intermediate portion of the substrate located between the first intermediate portion and the back surface along the line in the target, and
• (iii) the crack only extends between the front surface and the second intermediate portion of the substrate leaving the substrate intact from the second intermediate portion to the back surface as a result of the second step of emitting the second pulsed laser light into the substrate, and
• the first pulsed laser light has a pulse width that is shorter than a pulse width of the second pulsed laser light.