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Proceedings Paper

Resolution of the inverse problem of optical grating testing by means of a neural network
Author(s): Stephane Robert; Alain Mure-Ravaud
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Paper Abstract

The characterization of sub-micrometer period gratings by resolution of the inverse problem has become a real need in the area of the microelectronic. We present an optical scatteromettric method based on the use of a Neural Network (NN). This one permits to learn the relationship linking the diffracted efficiencies to the geometrical parameters. The great advantage of this method is to reject the limitations in resolution that occur with classical microscopic characterization. Theoretical results are demonstrated in this paper. The characterization can be achieved with accuracy close to 5 nm. We also study the index influence on the results and the importance of the choice of the assumed profile shape. Experimental results concerning a silicon 1-μm-period grating are also demonstrated. Finally, a comparison with results obtained by a microscopic characterization permits the validation of the presented method.

Paper Details

Date Published: 26 February 2004
PDF: 10 pages
Proc. SPIE 5252, Optical Fabrication, Testing, and Metrology, (26 February 2004); doi: 10.1117/12.514126
Show Author Affiliations
Stephane Robert, LTSI-CNRS (France)
Alain Mure-Ravaud, LTSI-CNRS (France)


Published in SPIE Proceedings Vol. 5252:
Optical Fabrication, Testing, and Metrology
Roland Geyl; David Rimmer; Lingli Wang, Editor(s)

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