Abstract: Capacitor structure capable of achieving increased energy storage density is disclosed together with a fabrication sequence for the capacitor and its anodic oxide dielectric material. Soft porous aluminum oxide which has been formed in a first anodization step and has been densified or transformed to hard barrier oxide in a second anodization step is preferred for the capacitor dielectric material. The first anodization may be performed in a sulfuric acid electrolyte while the second anodization may be performed in a boric acid electrolyte. The boric acid may be diluted with ethylene glycol. The disclosed capacitor is fabricated on a silicon wafer substrate.

Abstract: A metallic oxide such as aluminum oxide of significantly improved electrical properties is disclosed. The method of oxide formation includes a combination of soft porous anodization followed by transformation to a hard barrier form of oxide using inter alia low temperature electrolytes, constant voltage anodizing, and timely rate of current change responsive termination of the anodizing process. Use of the resulting oxide in electrical insulation, optic and other environments is contemplated.