| 摘要 |
PURPOSE:To align and compensate the position of the mask or the wafer with high accuracy by previously releasing internal stress due to a temperature change between chucks corresponding to the mask, etc. through previous vacuum sticking before original vacuum sticking is executed when the mask or the wafer is stuck to the chucks. CONSTITUTION:The silicon wafer to be stuck under vacuum is placed on the wafer chuck 2 in which a large number of vacuum holes are formed toward the surface, and luminous flux 5 for exposure is irradiated on the surface of the wafer 1. In the constitution, a pipe is drawn out of a cavity connected to a large number of the vacuum holes, and a vacuum source 4a for minute vacuum pressure generating vacuum weaker than a normal vacuum source on exposure is connected to the pipe through a valve 3a. A branching pipe is set up on its midway of the pipe , and a vacuum source 4b for normal vacuum pressure is connected similarly through a valve 3b. Accordingly, frictional force between the wafer 1 and the chuck 2 is reduced first to expand or contract the wafer 1 freely, and the wafer is stuck by normal vacuum pressure. |
