| 摘要 |
<p>PURPOSE:To prevent the damage of wafer and the generation of dust, by rotating the wafer to detect edge position variation in the non-contacting manner, calculating the eccentricity quantity and direction of wafer according to the detected results, and performing positioning. CONSTITUTION:A wafer 1 is mounted on a turn table by a conveying equipment (not shown in figure). A table 2 is rotated by a motor 4. The edge position lx of the wafer 1 is detected every specified rotation angle of the table 2, by a detector 5 constituted of a light projector 5a and a photo sensor 5b. The position lx is stored in a memory circuit 7 together with a table rotation angle gammax from an encoder 6. An operating circuit 8 calculates eccentricity quantity (x, y) and eccentric direction theta of the wafer 1 according to thetax, lx in the memory circuit 7. A control circuit 9 drives the motor 4 according to theta, and a control circuit 11 drives an XY table 10 according to (x, y). Centering of wafer 1 is enabled without contacting of edge and siliding of wafer, so that the damage of wafer and the generation of dust can be prevented.</p> |
