Determination of structural deviations in wire grid polarizers for DUV application wavelengths by transmission spectroscopy in the visible spectral range

Abstract

The optical performance of wire grid polarizers crucially depends on the fabrication accuracy. Reducing the application wavelengths to the ultraviolet spectral range sets the challenge that structural deviations in the range of typically a few nanometers become comparable to the feature sizes of the structure. In this contribution we present a concept to determine structural parameters and structural deviations of DUV wire grid polarizers fabricated with self-aligned double patterning. To this end, we evaluate the properties (i.e the spectral positions, the angular dependence of the spectral positions and widths) of asymmetry induced resonances in the transmittance spectra which occur at wavelengths larger than 380 nm. We derive requirements for measurement setup for nanoscale determination of the structural properties. Our results indicate that the investigation of the angular dependent transmittance at only two different wavelengths and one polarization state is sufficient to determine structural deviations with uncertainties of ±1:7nm for the effective shift of the ridge and ±0:34° for the effective tilt. Thus, the proposed method allows us to retrieve deep subwavelength structural information at the nanoscale with easily accessible transmittance measurements in the visible spectral range.