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Proceedings Paper

Low leaching and low LWR photoresist development for 193 nm immersion lithography
Author(s): Nobuo Ando; Youngjoon Lee; Takayuki Miyagawa; Kunishige Edamatsu; Ichiki Takemoto; Satoshi Yamamoto; Yoshinobu Tsuchida; Keiko Yamamoto; Shinji Konishi; Katsushi Nakano; Fujiwara Tomoharu
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Paper Abstract

With no apparent showstopper in sight, the adoption of ArF immersion technology into device mass production is not a matter of 'if' but a matter of 'when'. As the technology matures at an unprecedented speed, many of initial technical difficulties have been cleared away and the use of a protective layer known as top coat, initially regarded as a must, now becomes optional, for example. Our focus of interest has also sifted to more practical and production related issues such as defect reducing and performance enhancement. Two major types of immersion specific defects, bubbles and a large number of microbridges, were observed and reported elsewhere. The bubble defects seem to decrease by improvement of exposure tool. But the other type defect - probably from residual water spots - is still a problem. We suspect that the acid leaching from resist film causes microbridges. When small water spots were remained on resist surface after exposure, acid catalyst in resist film is leaching into the water spots even though at room temperature. After water from the spot is dried up, acid molecules are condensed at resist film surface. As a result, in the bulk of resist film, acid depletion region is generated underneath the water spot. Acid catalyzed deprotection reaction is not completed at this acid shortage region later in the PEB process resulting in microbridge type defect formation. Similar mechanism was suggested by Kanna et al, they suggested the water evaporation on PEB plate. This hypothesis led us to focus on reducing acid leaching to decrease residual water spot-related defect. This paper reports our leaching measurement results and low leaching photoresist materials satisfying the current leaching requirements outlined by tool makers without topcoat layer. On the other hand, Nakano et al reported that the higher receding contact angle reduced defectivity. The higher receding contact angle is also a key item to increase scan speed. The effort to increase the receding contact angle become very important issue for not only defectivity but also scanner throughput. Some of our experimental results along this line of study are also included in the report. The last topic covered is LWR (Line Width Roughness) as an essential leverage for performance improvement, especially for the smaller CD that immersion lithography is aiming to define. Our recent effort to find effect and working concept to reduce LWR with low leaching materials is also described.

Paper Details

Date Published: 11 April 2006
PDF: 9 pages
Proc. SPIE 6153, Advances in Resist Technology and Processing XXIII, 615322 (11 April 2006); doi: 10.1117/12.655586
Show Author Affiliations
Nobuo Ando, Sumitomo Chemical Co., Ltd. (Japan)
Youngjoon Lee, Sumitomo Chemical Co., Ltd. (Japan)
Takayuki Miyagawa, Sumitomo Chemical Co., Ltd. (Japan)
Kunishige Edamatsu, Sumitomo Chemical Co., Ltd. (Japan)
Ichiki Takemoto, Sumitomo Chemical Co., Ltd. (Japan)
Satoshi Yamamoto, Sumitomo Chemical Co., Ltd. (Japan)
Yoshinobu Tsuchida, Sumitomo Chemical Co., Ltd. (Japan)
Keiko Yamamoto, Sumitomo Chemical Co., Ltd. (Japan)
Shinji Konishi, Sumitomo Chemical Co., Ltd. (Japan)
Katsushi Nakano, Nikon Co. (Japan)
Fujiwara Tomoharu, Nikon Co. (Japan)

Published in SPIE Proceedings Vol. 6153:
Advances in Resist Technology and Processing XXIII
Qinghuang Lin, Editor(s)

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