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Proceedings Paper

Subresolution assist feature and off-axis illumination optimization for 200- and 240-nm contact windows using 248-nm lithography
Author(s): Pat G. Watson; Raymond A. Cirelli; Allen G. Timko; Omkaram Nalamasu; Carl Lockstamphor; Steven D. Berger; Neil J. Bassom; Ganesh Sundaram
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Paper Abstract

Sub-resolution assist features, coupled with appropriate off- axis illumination conditions, have been studied with the goal of fabricating 200 and 240 nm contact windows with uniform critical dimensions over a range of pitches and with large depths of focus (DOF). Results show that 240 nm isolated contacts without assist features possessed a useful DOF of less than 0.4 microns. The same features with 140 nm assist slots on each window edge, located 190 nm away, possessed a DOF of over 0.8 microns, using quadrupole illumination. Soft quadrupole illumination, where a mixture of quadrupole and conventional illumination is employed, yielded nearly the same DOF as quadrupole and printed both semi-dense and isolated contact windows near their optimum size as well. Contact holes, 200 nm wide, have been printed with smaller sub- resolution features, soft quadrupole illumination, and higher performance resists with a DOF of over 0.6 microns using a stepper with a numerical aperture of 0.53.

Paper Details

Date Published: 29 June 1998
PDF: 9 pages
Proc. SPIE 3334, Optical Microlithography XI, (29 June 1998);
Show Author Affiliations
Pat G. Watson, Lucent Technologies/Bell Labs. (United States)
Raymond A. Cirelli, Lucent Technologies/Bell Labs. (United States)
Allen G. Timko, Lucent Technologies/Bell Labs. (United States)
Omkaram Nalamasu, Lucent Technologies/Bell Labs. (United States)
Carl Lockstamphor, Lucent Technologies/Bell Labs. (United States)
Steven D. Berger, Micrion Corp. (United States)
Neil J. Bassom, Micrion Corp. (United States)
Ganesh Sundaram, Micrion Corp. (United States)

Published in SPIE Proceedings Vol. 3334:
Optical Microlithography XI
Luc Van den Hove, Editor(s)

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