SEM Measurements In Lithographic Metrology

Kenneth S. Maher; Hans R. Rottmann

doi:10.1117/12.949746

2 January 1986 SEM Measurements In Lithographic Metrology

Kenneth S. Maher, Hans R. Rottmann

Proceedings Volume 0565, Micron and Submicron Integrated Circuit Metrology; (1986) https://doi.org/10.1117/12.949746
Event: 29th Annual Technical Symposium, 1985, San Diego, United States

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.

Citation Download Citation

Kenneth S. Maher and Hans R. Rottmann "SEM Measurements In Lithographic Metrology", Proc. SPIE 0565, Micron and Submicron Integrated Circuit Metrology, (2 January 1986); https://doi.org/10.1117/12.949746

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