Patent ID: 7059607

Claim:
A positioning apparatus comprising: a box body including a process chamber exposed to a decompression environment in the interior of the box body and an opening allowing said process chamber to communicate with an area outside of the box body; a moving member for shielding said opening of said box body with a slight clearance between said box body and the moving member and movable with respect to said opening of said box body; a differential pumping seal for sealing said slight clearance between said opening of said box body and said moving member, wherein a portion of said moving member to be moved into the interior of said process chamber, when said moving member moves, is formed as an adsorption preventive area; cover member for covering at least the portion of said moving member movable between an interior side and an exterior side of said process chamber on said process chamber exterior side; and an air supply device for supplying a dry air having lower humidity than the atmosphere of said process chamber exterior side into said cover member.