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Proceedings Paper

Effects of aberration and flare on lithographic performance of SFET
Author(s): Yuusuke Tanaka; Hajime Aoyama; Kazuo Tawarayama; Shunko Magoshi; Seiichiro Shirai; Hiroyuki Tanaka
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Paper Abstract

The effects of aberration and flare on the lithographic performance of the EUV small-field exposure tool (SFET) were evaluated. Simulation results indicated that the effect of aberration on the image contrast of line-and-space (L&S) patterns should be small. In exposure experiments, 26-45-nm L&S patterns were successfully fabricated under annular illumination (σ=0.3/0.7). A key factor limiting resolution should be resist performance. Simulation results also indicated that the astigmatic aberration could produce a focal shift of about 60 nm between horizontal and vertical L&S patterns. The experimentally obtained focus shift agreed well with the simulation results. Dense 32-45-nm contact-hole (C/H) patterns were also successfully fabricated under annular illumination (σ=0.3/0.5). Due to astigmatic aberration, the C/H patterns were deformed at defocused positions, but they were almost circular at the best focus position. The flare of the projection optics measured by the Kirk method was 11% over a flare range of 1-100 μm. The effects of the 11% flare were evaluated using dark- and bright-field 32-nm L&S patterns. It was found that the top loss and line-width roughness (LWR) of the resist were larger for bright-field than for dark-field patterns. To reduce the impact of flare, we need EUV resists that are more robust with regard to flare. A comparison of the measured point spread function (PSF) of the flare and the calculated PSF revealed good agreement for long-range flare but some difference for short-range flare.

Paper Details

Date Published: 21 March 2008
PDF: 11 pages
Proc. SPIE 6921, Emerging Lithographic Technologies XII, 69211D (21 March 2008); doi: 10.1117/12.771626
Show Author Affiliations
Yuusuke Tanaka, MIRAI-Semiconductor Leading Edge Technologies, Inc. (Japan)
Hajime Aoyama, MIRAI-Semiconductor Leading Edge Technologies, Inc. (Japan)
Kazuo Tawarayama, MIRAI-Semiconductor Leading Edge Technologies, Inc. (Japan)
Shunko Magoshi, MIRAI-Semiconductor Leading Edge Technologies, Inc. (Japan)
Seiichiro Shirai, MIRAI-Semiconductor Leading Edge Technologies, Inc. (Japan)
Hiroyuki Tanaka, MIRAI-Semiconductor Leading Edge Technologies, Inc. (Japan)


Published in SPIE Proceedings Vol. 6921:
Emerging Lithographic Technologies XII
Frank M. Schellenberg, Editor(s)

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