Patent ID: 8054444

Claim:
A lithography system having an exposure apparatus including an objective lens, the lithography system comprising: a lens cleaning module for providing a cleaning fluid; an immersion fluid module different from the lens cleaning module for providing an immersion fluid, the immersion fluid being different than the cleaning fluid; a scanning stage for supporting a wafer beneath the objective lens, the scanning stage defining an exposure field; and a liquid retainer associated with the scanning stage, the liquid retainer including a fluid retaining wall carried by the scanning stage such that one of the cleaning fluid and immersion fluid is provided directly on the scanning stage and is retained by the fluid retaining wall for contacting the objective lens during exposure of the wafer, wherein the fluid retaining wall moves relative to the objective lens with movement of the scanning stage, wherein the lens cleaning module provides the cleaning fluid directly on the scanning stage such that only the cleaning fluid contacts the objective lens during cleaning of the objective lens.