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Proceedings Paper

SEM Measurements In Lithographic Metrology
Author(s): Kenneth S. Maher; Hans R. Rottmann
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Paper Abstract

As the dimensions of semiconductor devices on wafers approach the micron range, it is readily apparent that measurement of these types of geometries on the fab line will not be obtained using optical methods (1-4). In addition, non-destructive scanning electron microscopy methods must be found to make more representative measurements than those provided by fracturing of the specimen or use of conductive coatings. Further, measurements of semiconductor geometries on wafers must be made in-process. That is, the measurements must be made on uncoated specimens so that the specimen can be returned to the process quickly and intact to add layers for both product and monitoring wafers. The primary objective of this paper is to demonstrate procedures for using Scanning Electron Microscopes for small feature measurements in Lithography. To this purpose, test wafers were generated containing resist valleys with varying widths and slope angles (resist features present the most challenging measurement objects). A selected number of these features were measured on Scanning Electron Microscopes. Recorded were SEM micrographs, backscattered electron profiles and numerical data. In addition, the same features were also measured on optical measurement microscopes and the discrepancies between different systems were analyzed. A second objective of this study was to assess the usefulness of continued optical measurements in lithography because they are faster and considerably less expensive and, therefore, should continue to play an important part in lithography. It was also found that (uncontrollable) resist slope and adhesion variations are responsible for a major portion of optical measurement errors. Finally, a method will be proposed for the application of SEM systems to advanced lithographic process and equipment characterization and monitoring.

Paper Details

Date Published: 2 January 1986
PDF: 9 pages
Proc. SPIE 0565, Micron and Submicron Integrated Circuit Metrology, (2 January 1986); doi: 10.1117/12.949746
Show Author Affiliations
Kenneth S. Maher, IBM Corporation (United States)
Hans R. Rottmann, IBM Corporation (United States)

Published in SPIE Proceedings Vol. 0565:
Micron and Submicron Integrated Circuit Metrology
Kevin M. Monahan, Editor(s)

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