30 December 1999 Traceability, reproducibility, and comparability of grid calibrations
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The national metrology institute of Germany, PTB, offers traceable, two-dimensional pattern placement calibrations of microstructures on masks. Whereas the measurement uncertainty for the calibrated pattern positions in terms of traceable coordinate values is only comparable to the position tolerances actually required for mask patterning, i.e. about 35 nm, the deviations from the design grid can be determined with smaller uncertainties. In calibration certificates offered by PTB, these differences are taken into account and the uncertainties for the length of the grid and the uncertainties for the position deviations from the design grid are quoted separately as 30 nm and 10 nm respectively. Developments to further reduce the uncertainties are under way. An analysis of photomask recalibration results shows the long-term reproducibility of PTB length calibrations to be better than 15 nm or 1*10-7, including substrate stability effects. Details of the recalibration results will be given. Leica Microsystems Lithography runs a laboratory for two-dimensional pattern placement calibrations, formally accredited by PTB within DKD, the German calibration service. Results of recent comparison measurements between the DKD laboratory and PTB on masks of different size will be given and discussed as an example of the process of dissemination of the length unit to industry.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Harald Bosse, Harald Bosse, Wolfgang Haessler-Grohne, Wolfgang Haessler-Grohne, Bernd Brendel, Bernd Brendel, } "Traceability, reproducibility, and comparability of grid calibrations", Proc. SPIE 3873, 19th Annual Symposium on Photomask Technology, (30 December 1999); doi: 10.1117/12.373342; https://doi.org/10.1117/12.373342

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