Patent ID: 7242843

Claim:
An optical element suitable for photolithographic systems operating below 250 nm, including immersion photolithographic methods, said element comprising: a substrate that transmits electromagnetic radiation having wavelengths below 250 nm, said substrate having a first or top face and a second or bottom face, said electromagnetic radiation entering said second face, passing through said element and exiting said first face; optionally, one or a plurality of coating layers deposited on at least one of said first and second faces selected from the group consisting of anti-reflective coating, reflective or partially reflective mirror coatings, polarization coating, beam-splitter coating and other coating known in the art deposited on said substrate; a dense, durable coating of a hermetic sealing material deposited on at least one of said first and second faces, said layer being deposited over said optional layers when they are present; and optionally a sealing agent applied to the perimeter area of said hermetic sealing material and said substrate such that said sealing agent is in contact with both said substrate and said hermetic sealing material; wherein the hermetic material is fluorinated silicon dioxide having a fluorine content in the range of 0.5 wt. % to 4.5 wt. %.