| 摘要 |
PURPOSE:To release a suction holding state by disposing and opening a leakage hole communicating slightly with an atmosphere at the suction port side from a first switching valve in a suction passage for supplying negative pressure to a suction port to supply the atmospheric air from the hole to the suction port when the suction holding is released to set the suction port at positive pressure. CONSTITUTION:When a wafer 1 is placed on the suction surface 3 of a suction head 2, a switching valve 9 is opened, negative pressure is supplied to a suction port 5 through a tube 8, the valve 9 and an attraction passage 7, thereby holding the wafer 1 at the head 2. Then, when releasing the suction holding of the wafer, the valve 9 is closed, the supply of negative pressure from a negative pressure source is stopped, the negative pressure of the passage 7 is continuously leaked from a leakage hole 12, and the atmospheric air is relatively fed. Thus, the attraction force of the port 6 is gradually weakened to release the suction. At this time, since the inner diameter of the hole 12 is small, an impact applied to the wafer 1 is weak due to the flow of the atmospheric air. As a result, the wafer 1 is not moved on the suction surface 3. |
