Patent ID: 8115900

Claim:
A lithographic apparatus arranged to project a pattern from a patterning device onto a substrate, the lithographic apparatus comprising: an illumination system configured to condition radiation from a radiation source, the illumination system having an inner wall facing away from the radiation source and an outer wall facing toward the radiation source, the inner and outer walls having an aperture to allow radiation from the radiation source to pass into the illumination system; a pumping system configured to pump away gas; an outlet connected to the pumping system, the outlet located at or near the aperture and located between the inner wall and the outer wall of the illumination system or, if the lithographic apparatus comprises a radiation source, between the inner wall of the illumination system and an inner wall of the radiation source facing toward the radiation source and adjacent the inner wall of the illumination system; a suppression flow system configured to provide a gas flow to help prevent contamination particles from passing through the aperture in the direction of the radiation, the suppression flow system comprising a flow distributing structure, in the aperture, comprising a plurality of gas flow inlets extending in a direction transverse to the direction of the radiation and to enhance flow homogeneity in the direction transverse to the direction of the radiation; and a support structure constructed to hold the patterning device, the patterning device being capable of imparting the radiation with a pattern in its cross-section to form a patterned radiation beam.