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Proceedings Paper

Challenges with hyper-NA (NA>1.0) polarized light lithography for sub lambda/4 resolution
Author(s): Donis G. Flagello; Steven Hansen; Bernd Geh; Michael Totzeck
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Paper Abstract

The use of immersion technology will extend the lifetime of 193nm and 157nm lithography by enabling numerical apertures (NA) much greater than 1.0. This paper explores the effects that will occur when the high NA systems are augmented with polarization.. Specifically we show that there are strong interactions between the polarization induced by the reticle and polarization in the optics. This has a direct impact on the across-field specification of the polarization of the optical system as it causes a large variation in the imaging impact in photoresist. The impact of lens and reticle birefringence on the imaging is also analyzed. We show that reticle birefringence should not be a major concern when the birefringence is maintained to 2nm/cm - 4nm/cm levels. The lens can be modeled by a Jones matrix approach, where multiple pupils must be defined for each polarization state. We show the impact of the optical components by using a rigorous photoresist simulation on the process window of sub-50nm features using NA>1.3. The simulator uses a full Maxwell equation solver for the mask, polarized illumination, a Jones matrix approach for the pupil, and a photoresist simulation with calibrated model. The photoresist process is also shown to interact with polarization. Different photoresist will show varying degrees of sensitivity to polarization variation.

Paper Details

Date Published: 12 May 2004
PDF: 16 pages
Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2004); doi: 10.1117/12.599913
Show Author Affiliations
Donis G. Flagello, ASML US, Inc. (United States)
Steven Hansen, ASML US, Inc. (United States)
Bernd Geh, ASML US, Inc. (United States)
Michael Totzeck, Carl Zeiss (Germany)

Published in SPIE Proceedings Vol. 5754:
Optical Microlithography XVIII
Bruce W. Smith, Editor(s)

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