| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect an obliquely entered wafer among wafers in a wafer carrier. SOLUTION: A wafer carrier 21 houses stacked wafers 10 in rack plates each supporting both ends of the wafer, and is mounted on a lift table 23 which is moved up and down to take out the wafer 10 at a take-out position by hand only when this wafer is detect by both photoelectric sensors 25a, 25b. When only one sensor 25a indicates with its output signal that the wafer exists, it is a wafer 11 obliquely entered into a rack plate offset by one stage. The table 23 is moved by one pitch to the next rack plate during detecting by both sensors 25a, 25b. If only one sensor 25a generates an output signal indicating the wafer exists, it is a wafer 12 obliquely entered by two stages.</p> |
