Sub-Wavelength Features in Spectroscopic Mueller Matrix Ellipsometry

Spectroscopic Mueller matrix ellipsometry is a promising tool for the characterization of nanostructured surfaces. Direct optical measurements of samples with geometrical dimensions smaller than the incident wavelength are inherently limited by the classical resolution limit. However, as an indirect measurement technique, this limit does not apply to ellipsometry. In this contribution, we investigated the influence of manipulations of the near-field on the off-diagonal Mueller matrix elements. We designed and fabricated individual resist nanostructures on a silicon wafer. The structures possess distinct geometrical features in the range from several nanometers to a few micrometers and were produced by electron beam lithography. We performed spectroscopic measurements with a commercial ellipsometer to determine the Mueller matrices of the samples. In addition, nanosized silicon carbide grating structures were examined. Using a Finite Element software, we compared the measurements to simulations of the Mueller matrices to identify geometrical features.