| 摘要 |
PURPOSE:To enable a wafer to be registered to a reference position with a required accuracy by means of a noncontacting method, by rotating the wafer introduced onto a stage so as to detect data of peripheral positions and angles of rotation from which the deviation of the center of the wafer from the center of rotation and the orientation of the wafer are obtained. CONSTITUTION:When a wafer 1 is transported to and disposed on a chuck 2, the center Ow of the wafer is not aligned with the origin of coordinate axes that is the center of rotation of a rotary stage 7. In this state, an orientation flat is also orientated randomly. The rotary stage 7 is rotated clockwise by a motor 8 so that outputs YAn and YBn outputted from two line sensors 12A and 12B at intervals of a certain angle of rotation are stored in memory together with those angles of rotation. Two pairs of data obtained with respect to the angles of rotation spaced apart by 180 deg. are utilized for calculating a radius of the wafer R and an amount of deviation of the center of the wafer Ow from the original O at the subject angles of rotation. After that, the stage is operated correctively based on the result of this calculation.
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