Spatial periodicities inside the Talbot effect: understanding, control and applications for lithography

Displacement Talbot Lithography (DTL) is a simple patterning technique for creating periodic sub-micron features on wafer areas up to 200 mm diameter for applications in, for example, plasmonic, photonic crystals, and metamaterials. It exploits the diffraction and interference generally avoided in classical lithography. The Talbot effect, on which DTL is based, is the periodic spatial repetition of a periodic mask illuminated by coherent light. The modelling of this phenomenon is essential to fully understand and predict the interference pattern obtained; for mask periods greater than twice the wavelength, new spatial periodicities are generally introduced that are smaller than the Talbot length. This study reports simulations of multiple 1D masks to explain the influence of these smaller spatial periodicities on the Talbot effect. By changing the mask configuration, one can tailor the spatial periodicity contributions and thus, control the feature size, uniformity, and contrast for Talbot-effect-based lithography.