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Proceedings Paper

Proximity-effect correction for EPL by using multiple pattern-area-density maps and pattern classification
Author(s): Fumio Murai; Hiroshi Fukuda; Shigeki Mori; Akio Sato; Kyoji Nakajo
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Paper Abstract

In electron-beam projection lithography (EPL), the proximity effect is more complicated than in conventional direct electron-beam writing. The correction of this effect uses pattern-shape modification because dose adjustment is not possible. Moreover, large sub-field transcription produces non-uniform beam blur due to optical aberration and local and global Coulomb effects. This large beam blur requires sophisticated correction depending on pattern features and layout over a very short range as well as pattern density over a backscattering range. In response to these issues, the authors have developed a flexible and precise correction method for the proximity effect under various conditions of beam blur, LSI process, and pattern arrangement. It features (1) multiple pattern-area-density maps, (2) look-up tables classified by pattern features and layout, and (3) a fast calculation algorithm for the iteration process of optimal bias. The developed method (running on four PCs with 2.4-GHz CPUs) attains a processing time of 55 min by using a bias map for 12-GB LSI flat data in 2000 sub-fields. An example of pattern classification by this method showed the usefulness of pattern bias for each individual pattern edge over a short range. It is concluded that the developed correction method is useful not only for proximity effects, including the Coulomb effect, but also for various process effects in mask making with precise CD control.

Paper Details

Date Published: 28 August 2003
PDF: 10 pages
Proc. SPIE 5130, Photomask and Next-Generation Lithography Mask Technology X, (28 August 2003); doi: 10.1117/12.504235
Show Author Affiliations
Fumio Murai, Hitachi, Ltd. (Japan)
Hiroshi Fukuda, Hitachi, Ltd. (Japan)
Shigeki Mori, Hitachi ULSI Systems Co., Ltd. (Japan)
Akio Sato, Hitachi ULSI Systems Co., Ltd. (Japan)
Kyoji Nakajo, Hitachi ULSI Systems Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 5130:
Photomask and Next-Generation Lithography Mask Technology X
Hiroyoshi Tanabe, Editor(s)

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