Immersion lithography micro-objectives

The optical lithography community is quickly gaining confidence that immersion technology can further reduce critical dimensions based on theoretical models and high angle interference lithography techniques. The optical industry has responded by developing a new class of immersion lenses so that researchers can demonstrate practical imagery with lenses and immersion fluids with improved resolution. Corning Tropel has previously developed families of (dry) catadioptric objectives for industry researchers to help in the development phases of high resolution and inspection at wavelengths below 200 nm. They were designed for use with free running EXCIMER lasers for reduced cost and reduced sensitivity to environmental changes compared to monochromatic designs. New objectives based on the same design forms were developed for use with immersion fluids to extend the numerical aperture to values greater than 1.0 to help researchers extend the technology of small image formation. These objective designs will be described along with modeled performance and measured results.