Papers by Author: Harald Bosse

Abstract: Key comparison (KC) measurements are the backbone of validating the calibration and measurement capability (CMC) of national metrology institutes (NMIs) against each other. Recommendations providing procedures for the preparation and execution of KCs as well as supplementary comparisons are given. They are justified by mathematical reasoning and by aspects of practical use. Arguments and a formal description of calculating the key comparison reference value (KCRV) by its weighted mean based on the expanded measurement uncertainty expressed by a confidence level of 95 % will be presented. Moreover, it will be explained why the calculation of the normalized error relates to the weighted mean only and why its absolute value for the expanded measurement uncertainty shall be below 1 to pass the equivalence criterion (E_n) of comparability. A deeper discussion is given on how reference values and measurement results shall be treated if few individual measurement results differ significantly from the others. Finally, it will be explained how the proposed style of the graphical presentation of measurement results allows a clear visual interpretation of the comparison. Besides the formal description, numerical examples and diagrams are presented.

Abstract: To assure the metrological traceability of a measurement, it is required to perform an analysis of the measurement uncertainty specific to the measurement task. An approach to estimate the measurement uncertainty for complex systems is the so-called virtual measuring instrument: The measuring process is simulated taking into account its influencing parameters and a statistical analysis is performed by means of Monte-Carlo calculations. We present the development of such a virtual measuring instrument for scanning electron microscopy (SEM) which allows to estimate the measurement uncertainty in compliance with GUM for dimensional measuring tasks in nano- and microsystems technology. By application of this virtual instrument, model based corrections of systematic errors are made possible and the cognition of the strength of different perturbing influences can lead to recommendations to optimize measurement instruments and methods. The virtual model programmed in MATLAB is called ‘vREM’, it includes all essential components of the measuring chain of an SEM as modules: The electron source, the electron-optical lens-system, the scan-generator, the interaction of the electrons within the object, electron detectors, simple analysis procedures and consideration of external disturbances. By adjusting parameters uncertainty contributions can be assigned to the virtual probe, the virtual specimen and the virtual detector signals.

Abstract: A new Monte-Carlo program for simulation image formation in scanning electron microscopy for real three-dimensional use is presented; factors of image distortions are realized in the program, in respect of future photogrammetric evaluation. A first attempt for generating a 3D-analysis of simulated images is shown.