Improved grating reconstruction by determination of line roughness in extreme ultraviolet scatterometry

The accurate determination of critical dimensions and roughness is necessary to ensure the quality of photoresist masks that are crucial for the operational reliability of electronic components. Scatterometry provides a fast indirect optical nondestructive method for the determination of profile par...

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Bibliographic Details
Published in:Optics letters 2012-12, Vol.37 (24), p.5229-5231
Main Authors: Henn, Mark-Alexander, Heidenreich, Sebastian, Gross, Hermann, Rathsfeld, Andreas, Scholze, Frank, Bär, Markus
Format: Article
Language:English
Subjects:
Diffraction gratings
Gratings (spectra)
Inverse method
Mathematical analysis
Mathematical models
Reconstruction
Roughness
Ultraviolet
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Summary:The accurate determination of critical dimensions and roughness is necessary to ensure the quality of photoresist masks that are crucial for the operational reliability of electronic components. Scatterometry provides a fast indirect optical nondestructive method for the determination of profile parameters that are obtained from scattered light intensities using inverse methods. We illustrate the effect of line roughness on the reconstruction of grating parameters employing a maximum likelihood scheme. Neglecting line roughness introduces a strong bias in the parameter estimations. Therefore, such roughness has to be included in the mathematical model of the measurement in order to obtain accurate reconstruction results. In addition, the method allows to determine line roughness from scatterometry. The approach is demonstrated for simulated scattering intensities as well as for experimental data of extreme ultraviolet light scatterometry measurements. The results obtained from the experimental data are in agreement with independent atomic force microscopy measurements.
ISSN:0146-9592
1539-4794
DOI:10.1364/OL.37.005229