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Proceedings Paper

High sensitivity tracking of CD-SEM performance: QSEM
Author(s): S. Babin; Jaffee Huang; P. Yushmanov
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Paper Abstract

The performance of CD-SEMs directly affects the measured values of critical dimensions (CDs) at the time of their measurement. Tracking the performance of CD-SEMs is necessary to establish trust in their results and provide guidance for preventive maintenance and tune-ups. When the measured CDs are out of specification in manufacturing, it is crucial to determine whether this is due to process variation or the metrology tool itself. Multiple methods that use linewidth measurements have been employed thus far; however, they suffer from linewidth variations on the wafer, as well as from variations of line edge and linewidth roughness. Here, we report a method that is capable of providing a quantitative extraction of the SEM performance based on advanced algorithms. The method is independent of linewidth, line edge roughness and linewidth roughness, and has high sensitivity. This software, QSEM, was developed to automatically evaluate image quality and assign a value to that quality. The image quality value is based on multiple factors such as noise, sharpness, analysis of histograms, and contrast. The sensitivity of the software was evaluated; a good correlation between image quality results and linewidth variation due to SEM performance was established. Using QSEM to analyze SEM images allows the performance of CDSEMs to be tracked for proper calibration and preventive maintenance, as well as to resolve the dispute between failure in the process or the metrology.

Paper Details

Date Published: 19 March 2015
PDF: 8 pages
Proc. SPIE 9424, Metrology, Inspection, and Process Control for Microlithography XXIX, 942427 (19 March 2015); doi: 10.1117/12.2086069
Show Author Affiliations
S. Babin, aBeam Technologies, Inc. (United States)
Jaffee Huang, SCH Electronics (Taiwan)
P. Yushmanov, aBeam Technologies, Inc. (United States)


Published in SPIE Proceedings Vol. 9424:
Metrology, Inspection, and Process Control for Microlithography XXIX
Jason P. Cain; Martha I. Sanchez, Editor(s)

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