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Proceedings Paper

New spatial frequency doubling method for sub-0.15-um optical lithography
Author(s): Akihiro Otaka; Yoshio Kawai; Akinobu Tanaka; Tadahito Matsuda
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Paper Abstract

A new method for fabricating fine periodic patterns with a large depth of focus is proposed. It is based on flattening the 1st-order intensity distribution and extracting the 2nd-order intensity distribution which has a frequency twice that of the mask pattern. The resolution limit is improved up to the cutoff frequency of the projection system and the image can be created independently of the defocus and the pattern direction. This method is achieved by superposing the images at two focal planes under coherent illumination and it was demonstrated by KrF lithography with a conventional binary mask. A 0.14 micrometers lines-and- spaces pattern was fabricated with a large depth of focus of 2.0 micrometers . A contrast enhancement technique and pattern edge correction method needed for actual application of this method in device pattern fabrication are also discussed.

Paper Details

Date Published: 26 May 1995
PDF: 11 pages
Proc. SPIE 2440, Optical/Laser Microlithography VIII, (26 May 1995); doi: 10.1117/12.209307
Show Author Affiliations
Akihiro Otaka, NTT LSI Labs. (Japan)
Yoshio Kawai, NTT LSI Labs. (Japan)
Akinobu Tanaka, NTT LSI Labs. (Japan)
Tadahito Matsuda, NTT LSI Labs. (Japan)

Published in SPIE Proceedings Vol. 2440:
Optical/Laser Microlithography VIII
Timothy A. Brunner, Editor(s)

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