We have prepared Zr–Al thin-film capacitors by anodizing a sputter-deposited Zr–Al alloy film with 46 at. % Al, and examined their properties before and after heat treatment and their leakage current mechanism. In addition, anodized Zr–Al films were characterized by X-ray diffraction (XRD) analysis and Auger electron spectroscopy (AES). It is revealed that the reliability of an anodized pure-Zr capacitor is markedly improved by substituting the anodized Zr–Al film for anodized pure-Zr, because the crystallization of anodized Zr–Al amorphous films hardly occurs. In addition, it is clarified that the leakage current mechanism of the anodized Zr–Al capacitor is due to Schottky emission and that the thermal degradation observed after heat treatment above 350 °C is triggered by the diffusion of Zr atoms from the underlying unoxidized alloy layer into the anodized Zr–Al layer.

We have prepared an Al–Y anodized capacitor using sputter-deposited Al–Y alloy film with 5 at. % Y atoms, and evaluated the capacitor properties and the leakage current properties before and after heat treatment. In addition, the characterization of Al–Y anodized films was examined by X-ray diffraction, Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy analyses. As a result, it is revealed that the thermal stability of an Al–Y anodized capacitor is superior to that of a pure Al anodized capacitor because of its excellent passive nature, and the loss properties can be improved by increasing the heat treatment temperature in air because of the reduction of the equivalent series resistance. Furthermore, it is clarified that the cause of the short-circuited state observed at 550°C is the formation of a narrow capillary-like conduction path of metallic Al atoms as a result of the interdiffusion of Al.