Patent ID: 8830446

Claim:
An extreme ultraviolet exposure apparatus comprising: a radiation system configured to supply a beam of extreme ultraviolet radiation; a support configured to support a patterning device, the patterning device configured to pattern the beam of extreme ultraviolet radiation according to a desired pattern; a substrate table having an area configured to support a substrate; a projection system configured to project the patterned beam of extreme ultraviolet radiation onto a target portion of the substrate, the projection system comprising a reflective optical system; wherein at least a part of the apparatus that during use of the apparatus is exposed to the beam of extreme ultraviolet radiation is coated with an outer coating, the outer coating comprising a metal oxide, or a photocatalyst, or a semiconductor selected from the group consisting of: TiO 2 , SrTiO 3 , Fe 2 O 3 , WO 3 , and CdS, or any combination thereof, and wherein the part of the apparatus is part of the projection system or includes a sensor on the substrate table.