| 摘要 |
A device for centering an object and rotating it to a desired angular position relative to a discerning feature. The centration device is particularly adapted for use as a station in a semiconductor wafer handling apparatus, and includes a rotatably driven chuck on which a wafer may be placed by a robot manipulator arm. The perimeter of the wafer is rotated between a light source and a linear array of charge coupled device elements, casting a shadow on the light sensitive elements as the wafer is rotated. A processor connected to the charge couple devices and to an angular position encoder on a shaft of the chuck rotating the wafer is operative to collect data relating the displacement of the perimeter from a reference point to the angular position of the wafer. The processor determines from the data a distance over which the wafer should be shifted on the chuck to center it relative to the reference point. Once the robot manipulator arm has centered the wafer, a minimum displacement of a point on the perimeter corresponding to a flat or notch on the wafer is located and positioned at the desired angular orientation.
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