Characterization of aluminum oxide thin films obtained by chemical solution deposition and annealing for metal–insulator–metal dielectric capacitor applications

A novel chemical formulation is presented that enables the chemical solution deposition of aluminum hydroxide thin films, which transforms into aluminum oxide through subsequent annealing. The proposed method represents a faster and more economical alternative for aluminum oxide thin film deposition that can be used in metal-insulator-metal (MIM) dielectric capacitor applications. The film properties were studied in detail via X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and optical spectroscopy. It is demonstrated that the obtained thin films present high optical quality, low-crystalline domains, and oxygen vacancies. The films that were obtained for a 30 min deposition time show a suitable surface morphology and thickness, determined by atomic force microscopy and a cross-section from scanning electron microscopy, of a dielectric layer which was used to fabricate a MIM device. Using capacitance-voltage and current-voltage characterizations on that device, a low leakage current in the 10⁻⁴ A/cm² range and a capacitance of 98 and 48 nF/cm² were measured. These results indicate that, both aluminum hydroxide and aluminum oxide thin films have dielectric properties that are comparable to those of silicon oxide. Thus, the proposed method allows the deposition of gate dielectric films at low temperatures through a technically simple and scalable process.