Laser interference and nanospheres UV lithography to produce micro and nanostructured TiO2 and TiN based sol-gel layers

Abstract

In this paper, a direct and cost-effective sol-gel method to produce stable titanium dioxide and titanium oxynitride photoresists is described. This approach is compatible with many photolithographic techniques. We show that laser interference lithography and nanosphere lithography can be used, respectively, to obtain homogeneous TiO2 diffraction gratings and periodic nanopillars over large areas. Further developments permit to transform TiO2 microstructured based sol-gel to TiN metallic microstructured layer, with good optical properties, by using an innovative rapid thermal nitridation process, which opens the way towards plasmonics and NIR filters based on periodic metallic microstructured layers. Further technological processes were conducted to produce micro and nanostructured TiO2 and TiN layers from a NanoImprint approach. This work demonstrates the versatility of this complete process of soft chemistry new process of patterning TiO2 and TiN thin films avoiding expensive processes (etching, lift-off…) while preserving their diffractive properties and a high thermal stability, up to 1000°C. It is thus compatible to various types of substrates (of different shape and size). These results open up the opportunity to develop a cost-effective and low time-consuming approach to address different fields of cutting-edge applications (metasurfaces, sensors, luxury and decorative industry…).