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Proceedings Paper

Using multiple focal planes to enhance depth of focus
Author(s): Chris A. Spence; Daniel C. Cole; Barbara Peck
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Paper Abstract

The technique of exposing chips several times, changing the focal plane of the stepper between exposures, has been proposed by others as a way of improving the depth of focus when printing contact holes. We have investigated this technique with aerial image simulation, using criteria based on exposure and defocus latitudes. In addition, we have performed experiments using an i-line stepper to establish the correlation between simulation and what is achievable when printing images in resist. In this paper we investigate the following questions: (i) what is the optimum number of focal planes; (ii) what is the best separation of these planes; (iii) what is the effect on exposure dose; and (iv) what is the net process improvement?

Paper Details

Date Published: 1 June 1992
PDF: 11 pages
Proc. SPIE 1674, Optical/Laser Microlithography V, (1 June 1992); doi: 10.1117/12.130328
Show Author Affiliations
Chris A. Spence, IBM/General Technology Div. (United States)
Daniel C. Cole, IBM/General Technology Div. (United States)
Barbara Peck, IBM/General Technology Div. (United States)

Published in SPIE Proceedings Vol. 1674:
Optical/Laser Microlithography V
John D. Cuthbert, Editor(s)

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