Profile characterization of diffraction gratings using angle-resolved polarimetric measurements

Abstract

Development of the characterization tools and techniques used by semi-conductor industry directs not only towards increasing of the instrumental precision, to push limits of the optical characterization methods to the smallest lines, but also towards a decreased dependency of the used tools on the tool-to-tool calibration procedures. The challenge approached in this work is to use multiple independent optical configurations to determine overall accuracy of the results with minimal or no assistance of the other non-optical methods. The approach presented here is based on a well-known change of sensitivity of the optical model parameters at the different azimuthal measurement configurations. The full potential of this method can only be unlocked using complete Mueller matrix measurements providing complete information on the anisotropic nature of the gratings. The measurements at multiple azimuth configurations, used in this work, illustrate the potential of the method on the experimental data provided by the angle-resolved and spectrally resolved Mueller matrix polarimetric tools. The results are consistent with the single-line AFM measurements used as an independent reference.