Preparation of Tantalum‐Tantalum Oxide‐Manganese Oxide Structures by Photoexcited Anodic Deposition of Manganese Oxide

A novel preparation method for the tantalum‐tantalum oxide‐manganese oxide structure has been found that can be applied to fabrication of solid electrolytic capacitors. In the method, a uniform manganese oxide layer was electrolytically deposited from a bath of an aqueous Mn²⁺ salt solution on the anodically polarized tantalum oxide dielectric film. During the electrolysis, the dielectric film was irradiated with UV rays, the energy of which is enough to allow the valence electrons to enter the conduction band, so that the manganese oxide can be anodically deposited on the photoexcited tantalum oxide film. The photoexcited anodic oxidation for 15–30 min in the aqueous manganese(II) sulfate solution or manganese(II) acetate solution of pH 3–4 was the preferable condition to obtain a uniform manganese oxide layer. The several capacitor characteristics such as capacitance, tan δ, and leakage current of the formed structure were estimated.