Novel optical metrology for inspection of nanostructures fabricated by substrate conformal imprint lithography

Substrate conformal imprint lithography (SCIL) technology enables the fabrication of complex and non-trivial 3D nanostructures such a slanted gratings and metasurfaces with sub-10 nm resolution over large areas for industrial-scale production, which can be fabricated in a single lithography step. This technology utilizes novel composite silicone rubber stamps that provide versatility in addition to high precision. To inspect the quality and reproducibility of the nanostructures that are fabricated using SCIL, a novel optical characterization method using Fourier microscopy is proposed. In this method, nanostructures are illuminated under a microscope objective using a collimated light beam at different incident angles and the properties of the reflected and/or diffracted beams are analysed to extract the critical dimensions of the nanostructures. This fast and non-destructive method has the potential for being used as an in-line inspection technology to extract the critical dimensions of the nanostructures over large areas and improve the overall properties of nanostructured surfaces.