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Proceedings Paper

A new critical dimension metrology for chrome-on-glass substrates based on S-parameter measurements extracted from coplanar waveguide test structures
Author(s): Chidubem A. Nwokoye; Mona Zaghloul; Michael W. Cresswell; Richard A. Allen; Christine E. Murabito
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Paper Abstract

The technical objective of the work reported here is to assess whether radio-frequency (RF) measurements made on coplanar waveguide (CPW) test structures, which are replicated in conducting material on insulating substrates, could be employed to extract the critical dimension (CD) of the signal line using its center-to-center separation from the groundlines as a reference. The specific near-term objective is to assess whether this CPW-based CD-metrology has sensitivity and repeatability competitive with the other metrology techniques that are now used for chrome-on-glass (COG) photomasks. An affirmative answer is encouraging because advancing to a non-contact and non-vacuum implementation would then seem possible for this application. Our modeling of specific cases shows that, when the pitch of the replicated lines of the CPW is maintained constant, the sensitivity of its characteristic impedance to the CDs of the signal and ground lines is approximately 60 Ω/μm. This is a potentially useful result. For the same implementation, the quantity ∂C/∂w has a value of approximately 45 (pF/m)/μm, which appears to be large enough to provide acceptable accuracy.

Paper Details

Date Published: 20 October 2006
PDF: 11 pages
Proc. SPIE 6349, Photomask Technology 2006, 634946 (20 October 2006); doi: 10.1117/12.686706
Show Author Affiliations
Chidubem A. Nwokoye, George Washington Univ. (United States)
Mona Zaghloul, George Washington Univ. (United States)
Michael W. Cresswell, National Institute of Standards and Technology (United States)
Richard A. Allen, National Institute of Standards and Technology (United States)
Christine E. Murabito, National Institute of Standards and Technology (United States)

Published in SPIE Proceedings Vol. 6349:
Photomask Technology 2006
Patrick M. Martin; Robert J. Naber, Editor(s)

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