| 摘要 |
A balancing chuck is disclosed for semiconductor wafers having a flat region which typically causes wafer imbalance on spinning equipment. The wafer's flat region is determined by a proximity sensor mounted on a centering arm overlying the wafer. The chuck is constructed to include an annular race containing a spherical counterweight. As the chuck is rotated to determine the wafer's flat region, a magnet prevents movement of the spherical counterweight within the race and allows for its subsequent alignment with the mass imbalance. A plurality of circumferential pockets are provided within the race to retain the position of the counterweight which functions as a counterbalance maintained in proper angular alignment during spinning of the chuck.
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