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Proceedings Paper

Source modeling and calculation of mask illumination during extreme-ultraviolet lithography condenser design
Author(s): Lenny Laughlin; Jose M. Sasian
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Paper Abstract

Lithography condensers must create very uniform illumination at the mask plane. The non-uniformity in the illumination is required to be less than 1%. To meet this requirement a designer must use a method for determining the illumination created on the mask plane during the design of the condenser system. This paper describes a method for calculating the illumination at a plane in a lithography condenser system. This method is a general one that is applicable to many systems besides those for extreme ultraviolet lithography (EUVL). Our methodology uses reverse ray tracing to accurately and efficiently determine illumination in a system during the design phase. The technique is used with a standard optical design software package. This enables the system designer to test the illuminaton uniformity of the design with the same software that is used for the design work itself. Therefore, the user is not required to use illumination specific software to model the illumination properties for the design. Implementation of this new methodology necessitates accurate modeling of a source in the optical design software. The technique for modeling sources using apodization files is described. Results are shown for point sources, multiple point source configurations, and finite sources that have non-trivial surface radiance distributions. In some cases, the results of our method are compared to those found using a traditional technique of calculating illumination.

Paper Details

Date Published: 23 December 2002
PDF: 10 pages
Proc. SPIE 4832, International Optical Design Conference 2002, (23 December 2002); doi: 10.1117/12.486464
Show Author Affiliations
Lenny Laughlin, Optical Sciences Ctr./Univ. of Arizona (United States)
Jose M. Sasian, Optical Sciences Ctr./Univ. of Arizona (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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