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Proceedings Paper

Cost-effective overlay and CD metrology on phase-shifting masks
Author(s): Martin McCallum; Stewart Smith; Andrew Hourd; Anthony J. Walton; J. Tom M. Stevenson
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Paper Abstract

This paper presents the use of specially designed electrically testable structures to measure characteristics of alternating aperture phase-shifting masks (altPSM). The linewidths of chrome features on the mask are measured using modified cross-bridge structures, the technique behind this is explained together with the specific designs used to characterise both dense and isolated features. A practical, manufacturable solution to overcoming the problem of the non-conductive anti-reflective chromium oxy-nitride is given and results shown to prove its success. Correlation to more conventional CD measurements reinforce this result. A new technique, to measure the overlay of the second laye, used in the mask manufacture as the mask for the quartz etch establishing the phase shifted areas, is discussed. This entails using capacitive test structures in a progressional offset array to establish the minimum capacitance, indicating the overlay achieved. This technique has the added advantage of removing the errors created by mask sag in overlay metrology tools where the mask is held only at the edge. Results are presented indicating the success of this technique.

Paper Details

Date Published: 6 December 2004
PDF: 8 pages
Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); doi: 10.1117/12.568529
Show Author Affiliations
Martin McCallum, Nikon Precision Europe GmbH (United Kingdom)
Stewart Smith, Univ. of Edinburgh (United Kingdom)
Andrew Hourd, Compugraphics International Ltd. (United Kingdom)
Anthony J. Walton, The Univ. of Edinburgh (United Kingdom)
J. Tom M. Stevenson, The Univ. of Edinburgh (United Kingdom)


Published in SPIE Proceedings Vol. 5567:
24th Annual BACUS Symposium on Photomask Technology
Wolfgang Staud; J. Tracy Weed, Editor(s)

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