| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase the speed and accuracy for wafer positioning when finding the eccentricity of a wafer by rotating it. SOLUTION: In positioning a wafer by moving the center of the wafer to a prescribed position and directing the notch of the wafer to a prescribed direction, a spindle driving means positions the rotation axis line of the spindle on a straight line extended through the center of a line sensor, and then rotates the spindle mounted with the wafer about the rotation axis line thereof. Then, based on the angle of rotation of the spindle and the detection results of the outer edges of the wafer mounted on the spindle obtained from the line sensor, a calculation means finds out the position of the notch of the wafer and the maximum eccentric radius or the minimum eccentric radius of the wafer. From the obtained results, the position of the rotation axis line of the spindle and the angle of rotation when the center of the wafer is located at the prescribed position and the notch of the wafer is directed to the prescribed direction are geometrically calculated. Then, the spindle driving means moves and rotates the spindle so that the position of the rotary axis line and the angle of rotation of the spindle coincide with the calculated position of the rotation axis line and the angle of rotation of the spindle respectively, and then stops the spindle.</p> |
