An apparatus for reducing contamination in immersion lithography includes
a wafer chuck assembly having a wafer chuck configured to hold a
semiconductor wafer on a support surface thereof. The wafer chuck has a
gap therein, the gap located adjacent an outer edge of the wafer, and the
gap containing a volume of immersion lithography fluid therein. A fluid
circulation path is configured within the wafer chuck so as to facilitate
the radial outward movement of the immersion lithography fluid in the
gap, thereby maintaining a meniscus of the immersion lithography fluid at
a selected height with respect to a top surface of the semiconductor
wafer.