An EUVL device includes a wafer chamber that is separated from the upstream optics by a barrier having an aperture that is permeable to the inert gas. Maintaining an inert gas curtain in the proximity of a wafer positioned in a chamber of an extreme ultraviolet lithography device can effectively prevent contaminants from reaching the optics in an extreme ultraviolet photolithography device even though solid window filters are not employed between the source of reflected radiation, e.g., the camera, and the wafer. The inert gas removes the contaminants by entrainment.
The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Contract No. DE-AC04-94AL85000 awarded by the Department of Energy.