| 摘要 |
A polishing method and apparatus for reducing wafer taper in single-wafer polishing are disclosed, by which the whole processes from measurement of thickness profile of wafers and polishing thereof are fully automated and the working efficiency is not only improved, but also the polished wafers are produced with high accuracy in reduction of the taper thereof. The present invention is executed as follows: Thickness profiles of a wafer is measured with a measurement instrument of thickness in X,Y direction mutually perpendicular, and the taper T and stock removal S0 are determined from the thickness profiles with the method of least squares by a CPU and further the eccentricity delta , which is the distance between the center of the wafer and that of pressing force, is determined with the help of an equation delta =T.R/8.S0, where R is the radius of the wafer, by the CPU. The wafer is then transferred onto a positioning plate placed on an X,Y stage and the wafer is positioned at the position corresponding to the eccentricity delta supplied from the CPU by means of operation of the X,Y stage to finally be fixed on the positioning plate. The wafer, which is fixed thereon, is pressed on a polishing pad and polished, while the wafer is rotated about its center, the polishing table of a means for rotation and reciprocation thereof is rotated and reciprocated relative to its original position to give the wafer the relative revolutional motion and polishing slurry is constantly supplied. Thereafter, the thickness profiles of the as-polished wafer are again measured and at that point, if the taper is not reduced within the specification therefor, the second eccentricity delta is determined to obtain modified polishing conditions for a corrective single-wafer polishing.
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