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24 March 2006 Calibrating optical overlay measurements
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The National Institute of Standards and Technology (NIST) and The International Sematech Manufacturing Initiative (ISMI) have been involved in a project to evaluate the accuracy of optical overlay measurements in the presence of measurement target asymmetries created by typical wafer processing. The ultimate goal of this project is to produce a method of calibrating optical overlay measurements on typical logic and memory production stacks. A method of performing accurate CD-SEM and CD-AFM overlay measurements is first presented. These measurements are then compared to optical overlay measurements of the same structures to assess the accuracy of the optical measurements. Novel image rotation tests were also performed on these structures to develop a method to decouple errors from metrology target asymmetries and measurement system optical asymmetries.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
W. P. Lipscomb III, J. A. Allgair, B. D. Bunday, M. R. Bishop, R. M. Silver, R. Attota, and M. D. Stocker "Calibrating optical overlay measurements", Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 615211 (24 March 2006);

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