Laser machining apparatus for workpiece division, workpiece machining method, and workpiece division method

摘要

PROBLEM TO BE SOLVED: To provide a method for machining an object to be divided, by which the division of a workpiece is made more reliable.SOLUTION: An optical path from a light source, from which the pulsed laser beam having a pulse width of an order of psec is emitted, to a stage is partially branched into first and second optical paths in the midst. Then, as for individual unit pulsed beam, the optical path length of a second optical path is set so that a second half pulse beam which advances on the latter is delayed to a first half pulse beam which advances on the former, just by the delay time of not less than 1/3 times of a half-value width of a unit pulsed beam and not more than 10 nsec. Thereby, the regions to be irradiated of the first half pulse beam and the second half pulse beam are equal and, by emitting the pulsed laser beam so that the region to be irradiated for every individual unit pulsed beam is formed discretely on a surface to be machined, the cleavage or the dehiscence of the workpiece is generated between regions to be irradiated, and thereby, a starting point for division is formed on the workpiece.