Wafer processing method including formation of a deteriorated layer

A wafer processing method for dividing a wafer having function elements in areas sectioned by dividing lines formed on the front surface in a lattice pattern, into individual chips along the dividing lines, comprising:

• a frame supporting step for putting the front surface of the wafer on a support tape affixed to an annular frame;
• a deteriorated layer forming step for forming a deteriorated layer on the back surface of the wafer at a distance corresponding to the final thickness of the chip from the front surface of the wafer by applying a laser beam capable of passing through the wafer along the dividing lines from the back surface of the wafer supported by the annular frame through the support tape;
• a dividing step for dividing the wafer into individual chips along the dividing lines by applying external force to the wafer in which the deteriorated layer has been formed along the dividing lines;
• and
• a back surface grinding step for grinding the back surface of the wafer divided into individual chips to remove the entire deteriorated layer and to form the wafer to the final thickness of the chip;
• wherein, after the frame supporting step, a polish-processing step for polishing the back surface of the wafer is carried out before the deteriorated layer forming step.