Exposure apparatus, maintenance method therefor, semiconductor device manufacturing method using the apparatus, and semiconductor manufacturing factory

An exposure apparatus comprising:

• a reticle stage which holds a reticle;
• a reticle surface plate which supports said reticle stage, said reticle surface plate having an opening for transmitting exposure light;
• a projection optical system which projects a pattern of the reticle onto a substrate;
• and
• a sheet glass set on said reticle surface plate so as to separate a space inside the opening-of said reticle surface plate from a space above said reticle surface plate.

An exposure apparatus comprising:

• an optical system;
• a stage which moves with a flat object during exposure;
• and
• an enclosure which surrounds a space between said optical system and said stage through which exposure light passes,
• wherein said enclosure is arranged such that a gap is provided between a lower end thereof and said stage, and said stage has, around the flat object, a top plate with a surface flush with an upper surface of the flat object.