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Proceedings Paper

Measurement of a CD and sidewall angle artifact with two-dimensional CD AFM metrology
Author(s): Ronald G. Dixson; Neal T. Sullivan; Jason Schneir; Thomas H. McWaid; Vincent Wen-Chieh Tsai; Jerry Prochazka; Michael Young
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Paper Abstract

Despite the widespread acceptance of SEM metrology in semiconductor manufacturing, there is no SEM CD standard currently available. Producing such a standard is challenging because SEM CD measurements are not only a function of the linewidth, but also dependent on the line material, sidewall roughness, sidewall angle, line height, substrate material, and the proximity of other objects. As the presence of AFM metrology in semiconductor manufacturing increases, the history of SEM CD metrology raises a number of questions about the prospect of AFM CD artifacts. Is an AFM CD artifact possible? What role would it play in the manufacturing environment? Although AFM has some important advantages over SEM, such as relative insensitivity to material differences, the throughput and reliability of most AFM instruments is not yet at the level necessary to support in-line CD metrology requirements. What, then, is the most useful relationship between AFM and SEM metrology? As a means of addressing some of these questions, we have measured the CD and sidewall angle of 1.2 micrometer oxy-nitride line on Si using three different techniques: optical microscopy (with modeling), AFM, and cross sectional TEM. Systematic errors in the AFM angle measurements were reduced by using a rotational averaging technique that we describe. We found good agreement with uncertainties below 30 nm (2 sigma) for the CD measurement and 1.0 degrees (2 sigma) for the sidewall angles. Based upon these results we suggest a measurement procedure which will yield useful AFM CD artifacts. We consider the possibility that AFMs, especially when used with suitable CD artifacts, can effectively support SEM CD metrology. This synergistic relationship between the AFM and SEM represents an emerging paradigm that has also been suggested by a number of others.

Paper Details

Date Published: 21 May 1996
PDF: 17 pages
Proc. SPIE 2725, Metrology, Inspection, and Process Control for Microlithography X, (21 May 1996); doi: 10.1117/12.240113
Show Author Affiliations
Ronald G. Dixson, National Institute of Standards and Technology (United States)
Neal T. Sullivan, Digital Equipment Corp. (United States)
Jason Schneir, National Institute of Standards and Technology (United States)
Thomas H. McWaid, National Institute of Standards and Technology (United States)
Vincent Wen-Chieh Tsai, Univ. of Maryland/College Park (United States)
Jerry Prochazka, VLSI Standards, Inc. (United States)
Michael Young, Veeco/Sloan Technology (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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