Patent ID: 7554648

Claim:
A lithography system, comprising: a vacuum chamber comprising a first chamber portion and a second chamber portion; a member situated between the first and second chambers and defining an exposure aperture; a reticle stage situated in the first chamber portion and configured to hold a reticle movably relative to the exposure aperture; a gas-discharge port situated and configured to deliver a gas with a temperature gradient into the first chamber portion so as to establish a thermophoretic condition with respect to at least a portion of the reticle; a fixed-blind-aperture assembly that is movable relative to the exposure aperture and the reticle to an exposure position and to a non-exposure position, the fixed-blind-aperture assembly defining an illumination aperture through which light from the second chamber portion and gas from the first chamber portion can pass through the exposure aperture when the fixed-blind-aperture is in the exposure position; and a gas-passage aperture displaced from the exposure aperture so as to conduct the gas, passing through the illumination aperture, from the first chamber portion to the second chamber portion when the fixed-blind-aperture assembly is in the non-exposure position.