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Proceedings Paper

Spatial frequency analysis of optical lithography resolution enhancement techniques
Author(s): Steven R. J. Brueck; Xiaolan Chen
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Paper Abstract

A consistent frequency-space analysis of the effects of optical lithography resolution enhancement techniques including optical proximity correction, off-axis illumination, phase-shift masks and imaging interferometric lithography is presented. The improvements for each of these techniques are directly related to the enhanced frequency- space coverage afforded. Optical proximity correction extends the frequency coverage out to approximately 1.2-1.3 X NA/(lambda) where NA is the optical system numerical aperture and (lambda) the exposure wavelength enabling K1's of approximately 0.45 in the context of the Rayleigh resolution equation CD equals K2(lambda) /NA. There are many possible configurations for off-axis illumination. For a quadrupole oriented at 45 degrees to the (x,y) patterns axes, the maximum spatial frequency is extended to (root) 2NA/(lambda) or K1 approximately 0.43. Adding pupil plane filters to ensure a uniform MTF and orientating the quadrupole along the pattern axes allows extension to frequencies of 2NA/(lambda) or K1 approximately 0.3. Phase-shifts at the mask plane emphasize the high frequency image components by increasing the importance of the quadratic imaging terms and allow frequencies to 2NA/(lambda) and K1's out to approximately 0.35. Imaging interferometric lithography further extends the frequency coverage out to either (1 + NA)/(lambda) or 3NA/(lambda) depending on the details with corresponding K1 s of approximately 0.23-0.2.

Paper Details

Date Published: 26 July 1999
PDF: 11 pages
Proc. SPIE 3679, Optical Microlithography XII, (26 July 1999); doi: 10.1117/12.354388
Show Author Affiliations
Steven R. J. Brueck, Univ. of New Mexico (United States)
Xiaolan Chen, Univ. of New Mexico (United States)

Published in SPIE Proceedings Vol. 3679:
Optical Microlithography XII
Luc Van den Hove, Editor(s)

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