Patent ID: 7230673

Claim:
A lithographic apparatus comprising: an illumination system for conditioning a beam of radiation; a support for supporting a reticle, the reticle serving to impart the beam of radiation with a pattern in its cross-section, a surface of the reticle being protected by a pellicle attached thereto by a gas permeable pellicle frame; a reticle exchange unit comprising a reticle preparation chamber comprising a flow reducer, the flow reducer being constructed and arranged to obstruct gas flow to and from a space in the reticle preparation chamber that adjoins an exposed surface of the pellicle that faces away from the reticle; a reticle transport unit arranged to cause a plurality of exposed gas permeable parts of the pellicle frame to face an interior of the reticle preparation chamber before moving the reticle to the support; and a purge gas pressure and evacuating pressure supply arrangement arranged to provide, alternately, a purge gas pressure and an evacuating pressure that is lower than the purge gas pressure to the reticle preparation chamber when the exposed gas permeable parts of the pellicle frame are facing the interior of the reticle preparation chamber, so that gas flows through the pellicle frame, alternately, into and out of a pellicle space between the pellicle and the reticle.