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Proceedings Paper

Assessment of synchronous filtering as an alternative to phase-shifting masks at k1=0.4
Author(s): Andrew R. Neureuther; Meng Li
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Paper Abstract

This paper examines the extent to which off-axis illumination and pupil filtering can be combined as an interactive system to compensate the fundamental problem of the low diffraction efficiency of binary masks to improve working lithographic resolution. A sequential partial exposure and synchronous filtering technique is utilized which is a form of synthetic-aperture lithography (SAL) described by T. Sanstrom. An optimum off-axis illumination and filter transmission of 0.5 for an 0.35 (lambda) /NA equal line and space grating is shown to produce a lithographically useful contrast of 70 percent in best focus that only deteriorates to 63 percent at a full Rayleigh unit defocus. The feature type and size dependencies of this method are explored. Most improvement was observed for small dark feature in large bright fields which are suitable for printing small islands or logic gates in negative resists.

Paper Details

Date Published: 26 July 1999
PDF: 7 pages
Proc. SPIE 3679, Optical Microlithography XII, (26 July 1999); doi: 10.1117/12.354353
Show Author Affiliations
Andrew R. Neureuther, Univ. of California/Berkeley (United States)
Meng Li, Univ. of California/Berkeley (United States)

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

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