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Proceedings Paper

Ion beam processing for critical EUV photomask process steps: mask blank deposition and photomask absorber etch
Author(s): Katrina Rook; Meng H. Lee; Narasimhan Srinivasan; Vincent Ip; Sandeep Kohli; Mathew S. Levoso; Frank Cerio; Adrian J. Devasahayam
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Paper Abstract

Development progress and roadmap, for high-reflective Mo/Si multilayers for EUV mask-blanks, are reviewed. We outline the state-of-the-art in low-defect-density secondary ion beam deposition (IBD), and ongoing hardware development for performance improvement and high-volume manufacturing. We further discuss extension of ion beam technology to later steps in the EUV mask manufacturing: deposition of highly-uniform 2.5 – 3nm Ru capping layers; and patterning of novel Ni absorber structures. IBD-deposited Ru films are demonstrated with uniformity of 0.7% 3σ over a 188mm diameter area. By x-ray reflection with Cu Kα radiation, we measure a film density of 12.4 g/cm3, and a roughness of less than 1.0nm. Deposition rates of ~ 1 – 7 nm/min are demonstrated, implying a capping layer deposition time of 20 seconds – 3 minutes. . For advanced absorber patterning, we discuss Argon ion beam etch (IBE) of Ni films. Ni and Ru IBE etch rates of ~ 8 – 80 nm/min are demonstrated, implying absorber etch times of ~ 30 seconds – 5 minutes. IBE Ni:Ru etch selectivity is 1:1 to 1.3:1, so Ru is not a ‘stopping layer’, etch depth must be controlled by time, and Ni uniformity is a requirement. IBE Ni:Photoresist etch selectivity is 0.8:1 to 1.6:1. We simulate the IBE absorber pattern definition for mask features of half-pitch 96nm (24nm at wafer level). Ion beam incidence angle can be optimized to maintain critical dimension within 6% of the pre-etch value.

Paper Details

Date Published: 3 October 2018
PDF: 7 pages
Proc. SPIE 10809, International Conference on Extreme Ultraviolet Lithography 2018, 108090F (3 October 2018); doi: 10.1117/12.2501832
Show Author Affiliations
Katrina Rook, Veeco Instruments Inc. (United States)
Meng H. Lee, Veeco Instruments Inc. (United States)
Narasimhan Srinivasan, Veeco Instruments Inc. (United States)
Vincent Ip, Veeco Instruments Inc. (United States)
Sandeep Kohli, Veeco Instruments Inc. (United States)
Mathew S. Levoso, Veeco Instruments Inc. (United States)
Frank Cerio, Veeco Instruments Inc. (United States)
Adrian J. Devasahayam, Veeco Instruments Inc. (United States)

Published in SPIE Proceedings Vol. 10809:
International Conference on Extreme Ultraviolet Lithography 2018
Kurt G. Ronse; Eric Hendrickx; Patrick P. Naulleau; Paolo A. Gargini; Toshiro Itani, Editor(s)

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