2 June 2003 Lithography and metrology overlay troubleshooting by advanced query and multivariate analysis
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Abstract
Overlay specifications are getting tighter and lithographic processes come close to their limits. Minimal process changes can lead occasionally to overlay excursions. We explore the use of advanced query and multivariate analysis techniques to address overlay issues in an advanced production environment. We demonstrate the use of advanced query and multivariate analysis techniques in 4 case studies: identifying problem overlay recipes, comparing sources of variation in backend processing, identifying lithography tool issues, and overlay tool monitoring. Due to the large number of possible filter combinations several simple queries were used as starting points in order to explore the existing overlay database in a systematic way. The goal of the systematic evaluation of the available information was to find the most efficient methods to analyze and identify specific overlay problems. During this screening process, device, layer, and exposure tool specific metrics were found. For the most important findings the data filtering was refined in a second stage. Additional sources of information were incorporated for verification and to make correct conclusions. Standardized sets of queries can be used to monitor the lithographic process or to quickly pin point the root causes. It is shown that one can efficiently identify process, tool, and metrology sources of variation.
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Bernd Schulz, Bernd Schulz, Jens Krause, Jens Krause, John Charles Robinson, John Charles Robinson, Craig W. MacNaughton, Craig W. MacNaughton, } "Lithography and metrology overlay troubleshooting by advanced query and multivariate analysis", Proc. SPIE 5038, Metrology, Inspection, and Process Control for Microlithography XVII, (2 June 2003); doi: 10.1117/12.483470; https://doi.org/10.1117/12.483470
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