Patent ID: 6724460
Filing Date: 2004-04-20
Classification: G03F

Abstract:
A lithographic projection apparatus comprising:a radiation system to supply a projection beam of electromagnetic radiation having a wavelength of 250 nm or less; a support structure adapted to support patterning structure which can be used to pattern the projection beam according to a desired pattern; a substrate table to hold a substrate; a projection system to project the patterned beam onto a target portion of the substrate; and a gas supply constructed and arranged to supply a purge gas to a space in said apparatus, said space containing an optical component, wherein said purge gas comprises an oxygen-containing species selected from water, nitrogen oxide and oxygen-containing hydrocarbons; wherein said purge gas comprises an inert gas, and wherein the total amount of oxygen-containing species present in said purge gas is from 1 ppb to 10 ppm by volume.