| 摘要 |
PURPOSE:To prevent a wafer from dropping due to inertia when suction is stopped by disposing a stop member for stopping dropping of the wafer by operating according to the initial dropping operation of the wafer on a state on the outer periphery of the stage for placing the wafer. CONSTITUTION:When a wafer suction is stopped due to certain cause of suction strength is decreased during the moving of the stage device so that the wafer 5 moves in a dropping direction due to an inertia, the wafer 5 contacts a detector 32 corresponding to the movement side to turn its lever 34 against the tension of a spring 35, and a pawl 33 releases a connection rockable lever 40. The lever 40 released from the pawl 33 immediately turns by the tension of a spring 41 to oppose an end stopper 38 to a wafer dropping passage to prevent the wafer 5 from dropping. When the wafer 5 is moved to the intermediate direction between two preventing mechanisms 3, 3, the detecting members 32 of the both mechanisms operate to oppose the stoppers 38, 38 to prevent the wafer 5 from dropping.
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