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Proceedings Paper

Optimization of modified illumination for 0.25-um resist patterning
Author(s): Keiichiro Tounai; Shuichi Hashimoto; Seiichi Shiraki; Kunihiko Kasama
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Paper Abstract

In order to achieve wide focus latitude in various 0.25 micrometers patterns, the optimization of optical parameters in KrF excimer laser lithography has been investigated by means of optical intensity simulation. The accuracy of simulated DOF values was confirmed experimentally, using a chemically amplified negative resist and a KrF excimer laser stepper with NA equals 0.5 and sigma equals 0.7. The optical parameters, such as NA, sigma, and annular shield ratio in an annular illumination, were optimized for 1:1 L&S. Our results indicate that the DOF value in the conventional illumination is insufficient even under the optimum condition, but that in the annular illumination it is wide enough. To investigate the DOF value for sparse patterns the minimum contrast value, as well as the optimum optical parameters, was estimated for each defocal position. The optimum parameters set for sparse patterns was very different from that for 1:1 L&S. Moreover, the DOF value of sparse pattern was relatively small compared to that of 1:1 L&S.

Paper Details

Date Published: 17 May 1994
PDF: 11 pages
Proc. SPIE 2197, Optical/Laser Microlithography VII, (17 May 1994); doi: 10.1117/12.175436
Show Author Affiliations
Keiichiro Tounai, NEC Corp. (Japan)
Shuichi Hashimoto, NEC Corp. (Japan)
Seiichi Shiraki, NEC Corp. (Japan)
Kunihiko Kasama, NEC Corp. (Japan)

Published in SPIE Proceedings Vol. 2197:
Optical/Laser Microlithography VII
Timothy A. Brunner, Editor(s)

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