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Proceedings Paper

Accelerating EUV learning with synchrotron light: mask roughness challenges ahead
Author(s): Patrick P. Naulleau; Kenneth A. Goldberg; Eric Gullikson; Iacopo Mochi; Brittany McClinton; Abbas Rastegar
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Paper Abstract

Despite significant progress in the commercialization of extreme ultraviolet (EUV) lithography, many important challenges remain, including in the area of masks. The issue of EUV phase roughness that can arise from either multilayer or capping layer roughness has recently garnered increasing concern. The problem with mask phase roughness is that it couples line-edge roughness (LER) through the formation of image plane speckle. The coupling from phase roughness to LER depends on many factors including roughness magnitude, roughness correlation length, illumination partial coherence, aberrations, defocus, and numerical aperture. Analysis shows that only on the order of 50 pm multilayer roughness may be tolerable at the 22-nm half-pitch node. Results also show that Atomic Force Microscopy (AFM) may not be a suitable method for measuring mask phase roughness due to its sensitivity to the surface only. Capping layer roughness is another significant concern especially given that it has been shown to increase with cleaning cycles. In this case, however, AFM does provide a reasonable metric.

Paper Details

Date Published: 13 October 2011
PDF: 7 pages
Proc. SPIE 8166, Photomask Technology 2011, 81660F (13 October 2011); doi: 10.1117/12.900488
Show Author Affiliations
Patrick P. Naulleau, Lawrence Berkeley National Lab. (United States)
Kenneth A. Goldberg, Lawrence Berkeley National Lab. (United States)
Eric Gullikson, Lawrence Berkeley National Lab. (United States)
Iacopo Mochi, Lawrence Berkeley National Lab. (United States)
Brittany McClinton, Univ, of California, Berkeley (United States)
Abbas Rastegar, SEMATECH (United States)

Published in SPIE Proceedings Vol. 8166:
Photomask Technology 2011
Wilhelm Maurer; Frank E. Abboud, Editor(s)

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