GRINDER AND METHOD OF GRINDING

PROBLEM TO BE SOLVED: To provide a grinder in which the thickness of a wafer under grinding is measured without damaging the wafer. SOLUTION: This grinder comprises a chuck table for holding the wafer 11 and a grinding means having a grinding wheel for grinding the wafer 11 held on the chuck table. The grinder further comprises an actual thickness measuring means for measuring the actual thickness of the wafer 11, and a non-contact thickness measuring means 57 for emitting ultrasonic wave toward one surface of the wafer 11 and measuring at non-contact the thickness of the wafer 11 due to a time difference between the ultrasonic wave reflected on the one surface and the ultrasonic wave passing through the wafer 11 and reflected on the other surface of the wafer. The thickness of the wafer 11 before grinding is measured by the actual thickness measuring means to provide the initial thickness. A measurement reference value used in the calculation part of the non-contact thickness measuring means 57 is set according to the initial thickness. COPYRIGHT: (C)2009,JPO&INPIT