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Proceedings Paper

Scatterometry for CD measurements of etched structures
Author(s): Christopher J. Raymond; S. Sohail H. Naqvi; John Robert McNeil
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Paper Abstract

Scatterometry, the characterization of periodic structures via diffracted light analysis, has been shown to be a versatile technique for measuring critical dimensions in photoresist as small as 0.160 micrometer. Rapid, non-destructive and inexpensive, scatterometry has the potential to be applied to other microlithographic features as well. This paper discusses applications of scatterometry in the measurement of etched sub-um poly-Si line/space patterns. Since etched features represent the final dimensions of a finished product, the characterization of such features is important. Initial attempts at measuring the etched linewidth and height using scatterometry assumed the sidewalls were perfectly vertical. Although results from these two parameter predictions were good, our measurement algorithms suggested that the etch profiles were not square. Thus, sidewall angle was left as an unknown in our model and three parameter predictions were made. These improved results from measuring the linewidth, height and sidewall angle are presented, and comparisons to SEM measurements of the same samples are made. Finally, experiments to determine the repeatability of the scatterometer for measuring etched features were performed. Results show that the repeatability of the instrument, for both static and dynamic measurements of nominal 0.25 micrometer structures, is sub-nanometer for all parameters measured; the 3(sigma) repeatability for static CD measurements is 0.63 nm, and for dynamic measurements is 0.78 nm.

Paper Details

Date Published: 21 May 1996
PDF: 9 pages
Proc. SPIE 2725, Metrology, Inspection, and Process Control for Microlithography X, (21 May 1996); doi: 10.1117/12.240133
Show Author Affiliations
Christopher J. Raymond, Univ. of New Mexico (United States)
S. Sohail H. Naqvi, GIK Institute of Engineering Sciences and Technology (Pakistan)
John Robert McNeil, Univ. of New Mexico (United States)


Published in SPIE Proceedings Vol. 2725:
Metrology, Inspection, and Process Control for Microlithography X
Susan K. Jones, Editor(s)

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