3-D holographic lithography of organic-inorganic hybrids

Fabrications of ordered three-dimensional structures with submicron lattice constants were performed on organic-inorganic hybrids using a holographic lithography technique recently reported in the literature. The possibility of such a patterning has previously been demonstrated from single nanosecond laser pulse irradiation of thin films of epoxy photoresist and mixtures of methacrylate-alkoxy-silane with Zr or Ti alkoxides. In the present work, UV irradiation of similar hybrid resins were carried out through repeated laser pulses of low energy with a twofold objective: (i) to study the interference stability for future chemical gas phase decomposition experiments and (ii) to obtain patterning through large film thickness (e.g. 1 mm). The influence of several parameters on the structuration was examined from observations by scanning electron microscopy and optical diffraction. Many interdependent parameters were considered in different steps of the process, namely (i) hybrid resin preparations with required properties of stability, transparency and viscosity, (ii) film coating on different substrates, (iii) UV irradiation (energy and number of laser pulses), (iv) ultrasonic dissolution of monomer, and (v) sample drying. As results, different structuration resolutions were observed as a function of these parameters. But if the influence of a few parameters was easily understood and controlled, it has also appeared that it was not the case of all of them.