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Proceedings Paper

Study on surface integrity in photomask resist strip and final cleaning processes
Author(s): Sherjang Singh; Stefan Helbig; Peter Dress; Uwe Dietze
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Paper Abstract

In recent years, photomask resist strip and cleaning technology development was substantially driven by the industry's need to prevent surface haze formation through the elimination of sulfuric acid from these processes. As a result, ozone water was introduced to the resist strip and cleaning processes as a promising alternative to a Sulfuric - Peroxide Mixture (SPM). However, with the introduction of 193i double patterning, EUVL (Extreme Ultraviolet Lithography) and NanoImprint Lithography (NIL) the demand on CD-linewidth control and surface layer integrity is significantly expanded and the use of ozone water is questionable. Ozone water has been found to cause significant damage to metal based mask surface layers, leading to significant changes in optical properties and CD-linewidth shift. In this paper HamaTech APE demonstrates the use of an alternative acid-free resist strip and cleaning process, which not only overcomes the named drawbacks of conventional ozone water use, but reduces resist strip time by 50% to 75%. The surface materials investigated during this study are; chrome absorber layers on binary masks, MoSi based shifters, chrome hard mask layers on EPSM, and ruthenium capping layers on EUV masks. Surface material integrity and CD-stability results using this new, acid-free approach are presented in the following pages.

Paper Details

Date Published: 11 May 2009
PDF: 10 pages
Proc. SPIE 7379, Photomask and Next-Generation Lithography Mask Technology XVI, 73790D (11 May 2009); doi: 10.1117/12.824254
Show Author Affiliations
Sherjang Singh, Hamatech USA Inc. (United States)
Stefan Helbig, HamaTech APE (Germany)
Peter Dress, HamaTech APE (Germany)
Uwe Dietze, Hamatech USA Inc. (United States)

Published in SPIE Proceedings Vol. 7379:
Photomask and Next-Generation Lithography Mask Technology XVI
Kunihiro Hosono, Editor(s)

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