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Proceedings Paper

High-index optical materials for 193nm immersion lithography
Author(s): John H. Burnett; Simon G. Kaplan; Eric L. Shirley; Deane Horowitz; Wilfried Clauss; Andrew Grenville; Chris Van Peski
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Paper Abstract

We report on our comprehensive survey of high-index UV optical materials that may enable extension of immersion lithography beyond a numerical aperture of 1.45. Band edge, refractive index, and intrinsic birefringence (IBR) at 193 nm determine basic viability. Our measurements of these properties have reduced the list of potential candidates to: ceramic spinel, lutetium aluminum garnet, and a class of germanium garnets. We discuss our measurements of the intrinsic properties of these materials and assess the present status of their material quality relative to requirements. Ceramic spinel has no significant IBR, but transmission and scatter for the best samples remain at least two orders of magnitude from specifications. Improving these would require a major development effort. Presently available lutetium aluminum garnet has material quality much closer to the specifications. However, the IBR is about three times the required value. The germanium garnets offer the possibility of a lower IBR, but a suitable candidate material has yet to be established.

Paper Details

Date Published: 15 March 2006
PDF: 12 pages
Proc. SPIE 6154, Optical Microlithography XIX, 615418 (15 March 2006); doi: 10.1117/12.656901
Show Author Affiliations
John H. Burnett, National Institute of Standards and Technology (United States)
Simon G. Kaplan, National Institute of Standards and Technology (United States)
Eric L. Shirley, National Institute of Standards and Technology (United States)
Deane Horowitz, National Institute of Standards and Technology (United States)
Wilfried Clauss, Carl-Zeiss SMT AG (Germany)
Andrew Grenville, SEMATECH (United States)
Intel Corp. (United States)
Chris Van Peski, SEMATECH (United States)

Published in SPIE Proceedings Vol. 6154:
Optical Microlithography XIX
Donis G. Flagello, Editor(s)

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