| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent flatness of a wafer from deteriorating due to a foreign matter caught between a wafer and a wafer holder and suppress deformation of the wafer due to suction. SOLUTION: A protruding rim part 2 is formed on a base member 4 while being closed along the contour of a wafer and a large number of pins 1 are arranged in right triangular lattice within a region included in the rim part 2 to form a wafer holder WH. When a wafer is mounted on the wafer holder WH, the wafer is sucked at a high speed by opening a valve V2 communicating with a vacuum chamber 8a. Subsequently, a valve V1 communicating with a vacuum pump 7 is opened and the valve V2 is closed until the wafer is taken out from the wafer holder WH and the suction pressure (suction force) is lowered. When the wafer is taken out from the wafer holder WH, gas is blown to the bottom face of the wafer from an air supply unit 9 by opening a valve V3.</p> |
