US Patent 7767550 Wafer laser processing method and laser processing equipment

A wafer laser processing method for forming a groove in a wafer having a plurality of areas which are sectioned by streets formed in a lattice pattern on the front surface of a substrate, a device being formed in each of the plurality of areas, and an insulating film being formed on the surfaces of the devices, by applying a pulse laser beam along the streets, the method comprising a heating step for applying a first pulse laser beam set to an output for preheating the insulating film so as to soften it to the insulating film and a processing step for applying a second pulse laser beam set to an output for processing the insulating film and the substrate to the spot position of the first pulse laser beam applied in the heating step, the heating step and the processing step being carried out along the streets alternately.