Patent ID: 7134943

Claim:
A wafer processing method for dividing a wafer having optical devices that are formed in a plurality of areas sectioned by dividing lines formed in a lattice pattern on a front surface, along the dividing lines, comprising: a laser beam application step of applying a laser beam of a wavelength capable of passing through the wafer from the front surface thereof to a back surface thereof along the dividing lines with its focusing point set inside of the wafer to form deteriorated layers having a predetermined depth from the back surface of the wafer; a protective sheet affixing step of affixing a protective sheet to the front surface of the wafer having the deteriorated layers formed therein; a dividing step of dividing the wafer having the protective sheet affixed to the front surface along the deteriorated layers; and a grinding step of grinding the back surface of the wafer divided along the deteriorated layers in a state of the protective sheet being affixed to the wafer, to remove the deteriorated layers.