Patent ID: 7435607

Claim:
A wafer laser processing method for forming a deteriorated layer, which has been once molten and then re-solidified, in the inside of a wafer by applying a pulse laser beam capable of passing through the wafer, to the wafer along a dividing line formed on the wafer, comprising: a protective tape affixing step for affixing a protective tape having gas permeability to one side of the wafer; a wafer holding step for holding the wafer having the protective tape affixed thereto on a chuck table of a laser beam machine in such a manner that the one side of the wafer onto which the protective tape has been affixed comes into contact with the chuck table; and a laser beam application step for applying a pulse laser beam capable of passing through the wafer from the other side of the wafer held on the chuck table with its focusing point within the wafer at a position near the one side of the wafer to form the deteriorated layer exposed to the one side of the wafer along the dividing line in the inside of the wafer.