Photosensitive gel films prepared by the chemical modification and their application to surface-relief gratings

Abstract

A novel technique has been developed to fabricate surface-relief gratings using photosensitive gel films. Gel films which were derived from metal-alkoxides chemically modified with β-diketones were photosensitive owing to remaining chelate rings; the UV-irradiation of these gel films substantially decreased their solubility in acidic aqueous solutions or organic solvents. Leaching of the gel films after UV-irradiation through a mask and subsequent heat-treatment gave negative patterns of the mask used. Fine-patterns of PLZT films, as well as Al2O3, ZrO2, and TiO2 films, were successfully formed by the above process. Utilizing this process, surface-relief gratings were fabricated on silica glass and Si substrates by the irradiation of the modified gel films with a XeF excimer laser through a phase mask. Very uniform diffraction gratings with a pitch of about 1.0 μm were produced for Al2O3, ZrO2, and TiO2 films, along with PLZT films. The morphology and diffraction efficiency of the gratings obtained were examined in terms of fabrication conditions.