Challenges and Methodology of Fab-to-fab CD-SEM Matching

This paper describes the results of experiments performed to proof the tool-to-tool matching status of two CD SEM systems located in different wafer fabs in Asia, Europe, Israel and the United States. The methodology for setting up tools within one fab to ensure the matching of the signal generation between the tools has been extended to set up tools located in different fabs. In a second step a new methodology was developed to proof the matching, defined as getting the same measurement result on all tools, in different fabs. The main problem was the change of the structures on the wafers used for matching proof caused by the shipment. After verifying that the change to be the same no matter where the two tools under test are located, the change could be treated as an additional systematic effect not affecting the matching proof any longer. It is shown that by extension of the existing methodologies and by including the correction for systematic effects due to wafer shipment a matching level of all tools around the world similar to the matching level of tools within one fab can be achieved