Patent ID: 7696069

Claim:
A method of dividing a wafer having a plurality of streets which are formed in a lattice pattern on the front surface and devices which are formed in a plurality of areas sectioned by the plurality of streets into individual devices along the streets, the method comprising: a deteriorated layer forming step for applying a laser beam of a wavelength having permeability for the wafer, said laser beam being applied from the rear surface of the wafer along the streets to form a deteriorated layer, along the streets, in the inside of the wafer; a groove forming step for forming a groove in areas corresponding to the streets from the rear side of the wafer so that the deteriorated layer is exposed to the bottom of the groove; and a wafer dividing step for exerting external force to the wafer where the deteriorated layer and the groove have been formed to divide the wafer into individual devices along the streets where the deteriorated layer and the groove have been formed.