Modification of sol-gel-derived amorphous Al2O3 thin films by F-2 excimer laser irradiation at ambient temperature

F-2 excimer laser (157 nm) irradiation was applied to modify sol-gel-derive d amorphous Al2O3 thin films at ambient temperature. The surface morphology and density of the film were significantly altered by the laser irradiatio n (power: 2 mW/cm(2)/pulse). The surface properties of the film were also c hanged from hydrophilic to hydrophobic, These alterations were not observed when using ArF excimer laser (193 nm) irradiation at the same laser power as that of the F-2 laser. It was found that the changes induced by F-2 lase r irradiation mainly arose from the direct photoexcitation of C = O groups in ethylacetoacetate, which was added as a chelating agent of aluminum-alko xides. Consequently, photochemical reactions of the Norrish-type occur, res ulting in the formation of hydrocarbon or olefin and the elimination of car bon monoxide (CO) or decomposition products. The elimination of CO is consi dered to cause the marked change in structure and surface properties of the film. Patterning of the gel films was successfully performed by using thes e findings.