Chemical characteristics via quantitative photoelectron analysis of chemical-solution-deposited yttrium oxide thin films for metal-insulator-metal capacitor applications

A cost-effective chemical bath deposition coupled with an annealing methodology is presented for obtaining yttrium oxide (Y₂O₃) thin films. The resultant thin films are homogeneous, free of pinholes, and show a relatively low surface roughness. The detailed characterization of the as-deposited thin film and the determination of optical, structural, and chemical characteristics of the films upon thermal transformation at 500 °C for 2 h was done with thermogravimetric analysis, X-ray diffraction, UV–Vis spectroscopy, surface topology analysis, and X-ray photoelectron spectroscopy. The results reveal that the as-deposited thin film is composed of an amorphous YOOH compound intrinsic to the synthesis process. However, with annealing, it is crystallized and transformed into a Y₂O₃ thin film showing a high optical transparency. The characteristics of the film are found to be influenced by the Y‒OH and Y‒O content with direct influence on the shape of the photoelectron spectra of the thin films showing a binding energy downshift of 1.6 eV from the 158.84 eV peak position found for the YOOH sample after annealing. The estimated surface roughness for the as-deposited YOOH and annealed Y₂O₃ samples resulted in 2.7 and 3.8 nm, respectively. The electrical characteristics and potential performance as a dielectric layer have been assessed in a Metal-Insulator-Metal configuration, where the acceptable values for leakage current in the 6 × 10⁻⁴ − 3 × 10⁻⁶ A/cm² range and a capacitance of 218 and 80 nF/cm² were measured for the YOOH and Y₂O₃ thin films, respectively. The latter indicates that these films are suitable candidates for gate dielectric transistor applications with the advantage of them being films produced via an economical and technically simple scalable process.