Abstract
The effects of β-diketones on the stability and photosensitivity of Al2O3 gel films derived from Al (O-sec-Bu) 3 chemically modified with ethyl acetoacetate (EAcAcH), acetylacetone (AcAcH), or benzoylacetone (BzAcH) have been studied to develop a photolitic fine-patterning process for Al2O3 films. These gel films showed optical absorption bands, at around 270 nm (Al2O3/EAcAc), 290nm (Al2O3/AcAc), and 325nm (Al2O3/BzAc), characteristic of the π-π* transition of the chelate rings. Among the gel films investigated, the Al2O3/BzAc gel film was the most stable in an ambient atmosphere, as shown by the optical absorption spectra. Irradiation on the gel films with UV-light from a high-pressure mercury lamp dissociated the chelate rings, with increasing dissociation rate in the order EAcAc < AcAc < BzAc, and simultaneously decreased the solubility of the gel films in acetone containing HNO3. These results showed that the Al2O3/BzAc gel film was the most suitable for fine-patterning. This finding was successfully applied to the fine-patterning of Al2O3 films; the Al2O3/BzAc gel films were irradiated with UV-light through a mask, leached in HNO3-acetone solutions, and then heat-treated at 400°C to form finely patterned amorphous Al2O3 films on a variety of substrates.
