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Proceedings Paper

Global CD uniformity improvement for CAR masks by adaptive post-exposure bake with CD measurement feedback
Author(s): Lothar Berger; Werner Saule; Peter Dress; Thomas M. Gairing; C.-J. Chen; Hsin-Chang Lee; Hung-Chang Hsieh
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Paper Abstract

Progress towards 65nm next-generation lithography requires unprecedented global CD uniformity, with the actual ITRS 2002 roadmap proposing 4.2nm 3σ (dense lines) for 65nm binary masks. Since resolution requirements are satisfied only by using chemically amplified resists (CARs), exposure and post-exposure bake (PEB) are key processes to successful mask making, both introducing global CD errors. Develop and etch processes potentially contribute further global CD errors. The global CD uniformity can be improved significantly by adaptive PEB, especially for CARs showing moderate to strong PEB sensitivity, like NEB22. With the 25-zone hotplate of the APB5500 bake system, facilitated through a novel calibration mask with 25 equidistant temperature sensors within the resist plane, an appropriate temperature profile can be applied during PEB. This temperature profile is automatically calculated by an adaptive optimization algorithm, based on 2-dimensional spline fitting of a CD measurement. A CD-uniformity improvement (dense lines) from 3.80nm 3σ to 3.06nm 3σ (~20%) is achieved on evaluation photomasks with an 11x11 CD measurement grid.

Paper Details

Date Published: 20 August 2004
PDF: 7 pages
Proc. SPIE 5446, Photomask and Next-Generation Lithography Mask Technology XI, (20 August 2004); doi: 10.1117/12.557714
Show Author Affiliations
Lothar Berger, STEAG HamaTech AG (Germany)
Werner Saule, STEAG HamaTech AG (Germany)
Peter Dress, STEAG HamaTech AG (Germany)
Thomas M. Gairing, STEAG HamaTech AG (Germany)
C.-J. Chen, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
Hsin-Chang Lee, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)
Hung-Chang Hsieh, Taiwan Semiconductor Manufacturing Co., Ltd. (Taiwan)

Published in SPIE Proceedings Vol. 5446:
Photomask and Next-Generation Lithography Mask Technology XI
Hiroyoshi Tanabe, Editor(s)

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