Reduced basis method for real-time inverse scatterometry
Cell Transformation, Viral
Receptors, Cell Surface
Optical metrology by scatterometry usually bases on the comparison of experimental and modeled light field data. When solving inverse scatterometric problems, often not only a single simulation has to be carried out, but multiple electromagnetic field solutions have to be computed for varying material and geometrical parameters of the system under consideration. Then, high computational times for a single forward solution can make the complete simulation task infeasible. Table based parameter reconstruction on the other hand has the disadvantage of long offline computational times for creation of the library. Also an increasing number of variable parameters can not be handled efficiently. In this contribution we introduce the reduced basis method for creation of highly accurate reduced order models of parametrized electromagnetic scattering problems. We apply our method to a real-world EUV metrology application and show speed up factors of about 3000 in reconstruction time. Instead of several minutes or hours EUV mask parameters can now be obtained in seconds, i.e., in real-time. Comparison to direct microscopical measurements of the reconstructed geometry demonstrate the good performance and maturity of our method. © 2011 SPIE.
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