Patent ID: 7145641

Claim:
A lithographic projection apparatus comprising: a first radiation system that provides a beam of radiation; a support structure that supports a patterning structure, the patterning structure configured to pattern the projection beam according to a desired pattern; a substrate support that supports a substrate; a projection system that projects the patterned beam onto a target portion of the substrate, said projection system including an optical element that has a beam entry area and an optical element that has a beam exit area through each of which said patterned beam passes; a fluid cleaning system that cleans a fluid to be introduced into a region in which said optical element is disposed, said fluid cleaning system comprising a fluid inlet that receives fluid to be cleaned and a fluid outlet that supplies cleaned fluid to said region of said apparatus, a cleaning zone that cleans said received fluid, said cleaning zone being disposed between said inlet and said outlet, and a second radiation system that provides radiation to said cleaning zone to cause dissociation of a contaminant present in said fluid in said cleaning zone; and a nucleated surface provided with a plurality of nucleation sites, wherein said nucleated surface is disposed in said cleaning zone.