| 摘要 |
PURPOSE:To permit the chucking operation free from strain by successively vacuum-absorbing semiconductor wafers, etc. from a flowing port on the center side of a chuck surface and flowing gas into a flowing port not yet vacuum- absorbed, in a vacuum chuck for semiconductor wafers, etc. CONSTITUTION:When a movable valve 26 is shifted in the direction of arrow, the gas inflow ports 23a-23c close to the center point of the surface of a vacuum chuck 2 are closed in succession, and the vacuum suction ports 21a-21c close to the center point of the chuck surface are opened in succession, and ring- shaped grooves 22a-22c are vacuum-absorbed successively to absorb a wafer. Therefore, the wafer is a little lifted by the gas inflow, and when vacuum absorption is performed, absorption is performed successively from the center to the peripheral edge of the wafer flatwise and without leaving a strain, and the surface of the wafer is chucked flatwise, and the accuracy in patterning is improved. |
