Design and fabrication of near-to far-field transformers by sub-100 nm two-photon polymerization

Abstract

In recent years, technological progress in nanotechnology has pushed struc-ture sizes to its limits. As an example, in the semiconductor industry, structures well below 100 nm are routinely produced. The characterization of such structures is a de-manding and very important task. Classical microscopy methods do not allow direct imaging in this regime because of the Abbe diffraction limit. Nevertheless, charac-terization of sub-wavelength structures in the far-field is possible using interferomet-ric Fourier transform scatterometry (IFTS) combined with numerical simulation in a feedback loop. Here, we show that the resolution of this method can be considerably enhanced by use of additional plasmonic nanoantennae structures which transform scattering near-field information into the optical far-field. These structures were real-ized using different photofabrication approaches.