US Patent 7218377 Exposure apparatus and device manufacturing method

Disclosed is an exposure apparatus including a projection optical system for projecting a pattern of an original onto a substrate, a stage for holding the substrate, a cover for substantially surrounding an exposure light path, from an end portion of the projection optical system, at a side facing the stage, to the stage, a first supply port provided inside the cover, for supplying a purge gas into a space surrounded by the cover, and a first exhaust port provided in an end portion of said cover at a side facing the stage, for exhausting the gas.