| 摘要 |
PROBLEM TO BE SOLVED: To avoid dispersion of wafer thickness posed by an axial inclination of chuck tables when the thickness of wafers being chucked is measured with two-point in-process gauges. SOLUTION: One pair of contacts 17a and 17b of a two-point in-process gauge 17 is first put in contact with the surface of a chuck 9 carrying no wafers W to measure levels Tc0 and Tw0, and the identification number of the contact 17a or 17b that provides the greater level, and the level difference (t) as a correction value given by |Tc0-Tw0| are stored in a controller. For the computations of the thickness of the ground wafer W from the difference between new levels Tci and Twi that, during or after a grinding operation, the pair of contacts 17a and 17b of the two-point in-process gauge 17 measures again when put in contact with the surfaces of the chuck 9 and wafer W, the level Tci or Twi the number-stored contact 17a or 17b that has shown the greater initial level measures is subjected to correction, which subtracts the correction value (t) from it, before used in the difference calculation. |
