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Proceedings Paper

The impact of attenuated phase shift mask topography on hyper-NA lithography
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Paper Abstract

Thin mask approximations and Kirchhoff boundary conditions for imaging calculations are justified when patterns on masks are large compared to the imaging wavelength and the thickness of absorber films were relatively small compared with the wavelength. For the future technology nodes, these assumptions will not be sufficiently accurate for simulation of attenuated phase shift masks. At very high numerical apertures and extreme off-axis illumination angles, changes in the optical path length and shadowing by the mask topography can lead to phase and amplitude deviations between the thin mask approximation and the more rigorous, full Maxwell equations approach. We have found a systematic, non-constant transmission and phase variation through pitch for low k1 imaging that is not found with the thin-mask approach. In this paper, the major impacts of attenuated phase shift mask topography in the presence of extreme off-axis illumination with numerical apertures greater than one is investigated and the contribution of mask topography to CD errors on the wafer is explored. Consideration of this new mask component to CD error budgets is needed when debating the advantages and disadvantages in a reticle magnification change.

Paper Details

Date Published: 4 November 2005
PDF: 11 pages
Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59920Z (4 November 2005); doi: 10.1117/12.632510
Show Author Affiliations
Chris A. Mack, KLA-Tencor Corp. (United States)
Mark D. Smith, KLA-Tencor Corp. (United States)
Trey Graves, KLA-Tencor Corp. (United States)

Published in SPIE Proceedings Vol. 5992:
25th Annual BACUS Symposium on Photomask Technology
J. Tracy Weed; Patrick M. Martin, Editor(s)

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