Lithographic apparatus and device manufacturing method

A lithographic apparatus includes a support constructed to support a patterning device that is capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, a projection system configured to project th...

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Bibliographic Details
Main Authors Van Der Net, Antonius Johannes, Van Empel, Tjarko Adriaan Rudolf, Van Der Ham, Ronald
Format Patent
LanguageEnglish
Published 05.06.2007
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Summary:A lithographic apparatus includes a support constructed to support a patterning device that is capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, a projection system configured to project the patterned radiation beam onto a target portion of the substrate, an interior space through which an interferometer beam propagates, and a first gas supply for supplying a purge gas to inhibit contamination of the projection system. The purge gas has a predetermined refractive index. The apparatus also includes a second gas supply for supplying a conditioning gas to the interior space for conditioning the interior space, and a refractive index matching system arranged to match the refractive index of the conditioning gas to the predetermined refractive index of the purge gas.