| 摘要 |
<p>PURPOSE:To realize a lightweight and thin apparatus while a strain to be caused by a pressure difference between a vacuum pressure and an outside-air pressure is prevented by providing the following: protrusions arranged at nearly equal intervals on the rear surface of a suction plate; a soft sheet-Iike separation means used to separate a vacuum part inside the suction plate and an outsideair chamber while it comes into contact with tip parts of the protrusions; an outside-air layer formed between the suction plate and a base. CONSTITUTION:Protrusions 9 arranged in a vacuum chamber 6 disperse a force generated by a pressure difference between the vacuum chamber 6 and an outside-air layer 7 separated from the chamber by a plate 8; they are installed in such a way that the plate 8 does not close small holes when air in the vacuum chamber 6 is sucked. When the air inside the vacuum chamber 6 is sucked through a suction port 4, a pressure inside a plurality of small holes 5 arranged at nearly equal intervals so as to be interlinked with the vacuum chamber becomes lower than an outside-air pressure; a wafer 1 is sucked to a suction face of a suction plate 2 after its plane has been corrected. During this process, both the surface and the rear of the suction plate 2 are under the outside-air pressure; a deformation force by a pressure difference between the surface and the rear does not act on the suction plate 2. In addition, a force generated by a pressure difference between the vacuum chamber 6 installed at the lower part of the suction plate 2 and the outside-air layer 7 separated from the vacuum chamber by the plate 6 deforms only the plate 8; a deformation of the suction plate 2 whose rigidity is sufficiently higher than that of the plate is not caused.</p> |
