Comparison of different approaches for modelling microscope images on the basis of rigorous diffraction calculation

Bernd Bodermann; Gerd Ehret

doi:10.1117/12.612632

29 August 2005 Comparison of different approaches for modelling microscope images on the basis of rigorous diffraction calculation

Bernd Bodermann, Gerd Ehret

Author Affiliations +

Proceedings Volume 5858, Nano- and Micro-Metrology; 585809 (2005) https://doi.org/10.1117/12.612632
Event: Optical Metrology, 2005, Munich, Germany

Abstract

High resolution optical microscopy is still an important instrument for dimensional characterisation of micro- und nanostructures. For precise measurements of dimensional quantities a highly accurate modelling of the optical imaging on the basis of rigorous diffraction calculation is essential, which accounts for both the polarisation effects and the 2D or 3D geometry of the structures. Some applications like for example the measurements of linewidths on photomasks demands for measurement uncertainties of few nm or less. For these requirements the numerical and the model induced uncertainty, respectively, may be limiting factors even for sophisticated modelling software. At PTB we use two different rigorous grating diffraction models for modelling of the intensity distribution in the image plane, the rigorous coupled wave analysis (RCWA) method and the finite elements (FEM) method. In order to evaluate the performance of both methods we performed comparative calculations on the basis of a test suite of binary chrome on glass gratings with different line widths reaching from 100nm to 10μm, and with different line/space ratios between 0.01 and 100. We present results of this comparison for TE, TM and unpolarised Koehler illumination of the grating. Residual deviations between both methods and the resulting measurement uncertainty and related to the corresponding time consumptions are considered.

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Bernd Bodermann and Gerd Ehret "Comparison of different approaches for modelling microscope images on the basis of rigorous diffraction calculation", Proc. SPIE 5858, Nano- and Micro-Metrology, 585809 (29 August 2005); https://doi.org/10.1117/12.612632

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