We achieved the preparation of nanostructures based on negative tone inorganic resists by DUV lithography (193 nm). This entails the preparation of a complex of a transition metal by reaction between the metal alkoxide and a suitable ligand. The reaction was carried out in a solvent. Then, a partial hydrolysis of the complex allowed forming metal-oxides inorganic chains by condensation with good film-forming and photopatterning properties. This step corresponds to the synthesis of multifunctional oligomers that can be crosslinked by DUV irradiation.
We obtained well-defined patterns exhibiting low rugosity with width down to 75 nm. An achromatic interferometer based on an ArF excimer laser was used to write the nanostructures. The sensitivity of the resin at 193 nm is in the order of magnitude of organic photoresists used in the microelectronics industry.
The photoinduced processes were studied with care in order to state the physico-chemical phenomena occurring upon DUV-irradiation. FTIR, XPS and XRD were used for characterizing the material structure after irradiation and thermal treatment. Nanostructures were studied by AFM.
The main interest of this resist is that after irradiation, the material is mainly inorganic. It can even be totally mineralized through a subsequent pyrolysis procedure. The process is compatible with a wide range of chemicals (ZrO2, TiO2…). Using lithographic route, it is possible to obtain such nanostructures on relatively wide surfaces. With this new process, we are targeting applications in microelectronics, optics, photonics, photocatalysis, photovoltaic…