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Proceedings Paper

Low-defect EUVL multilayers on standard-format mask blanks
Author(s): James A. Folta; Patrick A. Kearney; Cindy C. Larson; Michael K. Crosley; Emily Fisch; Kenneth C. Racette
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Paper Abstract

Fabrication of low defect density mask blanks remains as one of the key challenges to commercialization of Extreme Ultraviolet Lithography (EUVL). A low defect deposition process for EUV-reflective Mo/Si multilayers has been developed on 200mm silicon substrates because of the availability of sensitive, fast defect inspection tools for wafers. A defect level of 0.05 defects/cm2 at 90 nm defect size detection threshold can now be achieved repeatedly on wafers. We upgraded the low defect multilayer deposition (LDD) system to allow coating of standard format 152mm square mask blanks. Mask blank defect inspection was performed at IBM with a typical sensitivity of 100 nm PSL equivalent. We used the single reticle SMIF pod (RSP) standard both for clean, automated handling and for shipping of the mask substrates and blanks. The added defect level during shipping was improved to 0.02 defects/cm2. We achieved a process-added defect density of 0.38 defects/cm2 on a lot of 5 blanks, which was the same defect level as on wafers coated before and after the blanks. We also improved the reflectance and thickness control on blanks to achieve 66.5% EUV reflectance, and a thickness uniformity of 0.07% P-V or 0.04% rms. The improved reflectance and uniformity meet the SEMI P38 specifications for EUVL mask blanks. We have discovered no differences in defect levels or film quality in the coating of standard square format as compared to silicon wafers.

Paper Details

Date Published: 27 December 2002
PDF: 8 pages
Proc. SPIE 4889, 22nd Annual BACUS Symposium on Photomask Technology, (27 December 2002); doi: 10.1117/12.467478
Show Author Affiliations
James A. Folta, Lawrence Livermore National Lab. (United States)
Patrick A. Kearney, Lawrence Livermore National Lab. (United States)
Cindy C. Larson, Lawrence Livermore National Lab. (United States)
Michael K. Crosley, Lawrence Livermore National Lab. (United States)
Emily Fisch, IBM Microelectronics Div. (United States)
Kenneth C. Racette, IBM Microelectronics Div. (United States)

Published in SPIE Proceedings Vol. 4889:
22nd Annual BACUS Symposium on Photomask Technology
Brian J. Grenon; Kurt R. Kimmel, Editor(s)

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