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Proceedings Paper

The development of dioptric projection lenses for DUV lithography
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Paper Abstract

Advanced dioptric projection lenses from Carl Zeiss are used in some of the world's most advanced deep ultraviolet projection lithography systems. These lenses provide a resolution of better than 100 nm across the entire field of view with a level of aberration control that maximizes critical dimension uniformity and lithographic process latitude. These dioptric projection lenses are currently being used for critical layer device patterning for a wide array of complex logic, memory, and application specific integrated circuits. Zeiss' involvement in the develop of ultraviolet lenses goes back to the year 1902, exactly 100 years ago, when Moritz von Rohr calculated the first monochromatic ultraviolet micro-objectives for ultra-high resolution microphotography using a line-narrowed source. The modern dioptric projection lenses for lithography are influenced by the collective experience in the field of microscopy, and the more recent experience with early step-and-repeat lenses. This paper discusses some of the foundations of modern dioptric designs in the context of this history, demonstrating that rapid synthesis of designs is possbile using combinations of monochromatic microscope objectives and early step-and-repeat lenses from the 1970's. The problems associated with ultra high numerical aperture objectives are discussed. Specifically, it is demonstrated that aspheres can be used effective to reduce the volume of full field projection lenses, making the mechanical implementation of a 0.90 NA lens feasible in production. Several contemporary dioptric projection lens designs are reviewed in detail. The extension of these designs to numerical apertures greater than 1.0 using immersion techniques is demonstrated. These immersion lenses give the potential for 40 nm resolution.

Paper Details

Date Published: 23 December 2002
PDF: 12 pages
Proc. SPIE 4832, International Optical Design Conference 2002, (23 December 2002); doi: 10.1117/12.486477
Show Author Affiliations
Wilhelm Ulrich, Carl Zeiss SMT AG (Germany)
Hans-Juergen Rostalski, Carl Zeiss SMT AG (Germany)
Russell M. Hudyma, Paragon Optics, Inc. (United States)

Published in SPIE Proceedings Vol. 4832:
International Optical Design Conference 2002
Paul K. Manhart; Jose M. Sasian, Editor(s)

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