Patent ID: 8178423

Claim:
A laser beam machining method for machining a transparent substrate of a wafer through ablation by irradiation with a laser beam, the wafer having a functional layer formed on a surface of the transparent substrate and having devices formed respectively in a plurality of regions demarcated by a plurality of streets arranged in a grid pattern on the surface, the method comprising: a holding step of holding the wafer; a setting step of alternately setting in each of the streets machining areas in which to form machined grooves and machining start point areas in which to form shallow grooves shallower than the machined grooves, and storing the setting information in a storage section; and a machining step of continuously forming the machined grooves and the shallow grooves by scanning an irradiation point of the laser beam from one end toward the other end of each of the streets, based on the setting information stored in the storage section.