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Proceedings Paper

DOF enhancement effect of attenuated assist feature
Author(s): Shinji Ishida; Shuichi Hashimoto; Tadao Yasuzato; Kunihiko Kasama
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Paper Abstract

To improve the depth of focus (DOF) of isolated lines, attenuated assist feature (AAF) technique has been proposed; AAFs having more than 20 % transmittance were located around an isolated line. In this mask, the transmittance & phase shift angle of AAF as well as its position & width have effects on lithographic performance. In particular, the phase shift angle has strong effect on focus latitude. The performances of two AAF masks (65 % transmittance/ 28° phase shift and 40 % transmittance/ 54° phase shift) were evaluated by using an NA=0.6, σinout = 0.42/0.7, i-line stepper. The focus latitude of 0.3 μm isolated line became flat around the best focus position with 28(degree) phase shift AAFs. In conclusion, we can obtain wide DOF for isolated lines by selecting optimum phase shift angle of AAF.

Paper Details

Date Published: 24 July 1996
PDF: 9 pages
Proc. SPIE 2793, Photomask and X-Ray Mask Technology III, (24 July 1996); doi: 10.1117/12.245202
Show Author Affiliations
Shinji Ishida, NEC Corp. (Japan)
Shuichi Hashimoto, NEC Corp. (Japan)
Tadao Yasuzato, NEC Corp. (Japan)
Kunihiko Kasama, NEC Corp. (Japan)


Published in SPIE Proceedings Vol. 2793:
Photomask and X-Ray Mask Technology III
Hideo Yoshihara, Editor(s)

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