Anodic Oxidation in Aluminum Electrode by Using Hydrated Amorphous Aluminum Oxide Film as Solid Electrolyte under High Electric Field

Dense and nonporous amorphous aluminum oxide (AmAO) film was deposited onto platinized silicon substrate by sol–gel and spin coating technology. The evaporated aluminum film was deposited onto the AmAO film as top electrode. The hydrated AmAO film was utilized as a solid electrolyte for anodic oxidation of the aluminum electrode (Al) film under high electric field. The hydrated AmAO film was a high efficiency electrolyte, where a 45 nm thick Al film was anodized completely on a 210 nm thick hydrated AmAO film. The current–voltage (I–V) characteristics and breakdown phenomena of a dry and hydrated 210 nm thick AmAO film with a 150 nm thick Al electrode pad were studied in this work. Breakdown voltage of the dry and hydrated 210 nm thick AmAO film were 85 ± 3 V (405 ± 14 MV m^–1) and 160 ± 5 V (762 ± 24 MV m^–1), respectively. The breakdown voltage of the hydrated AmAO film increased about twice, owing to the self-healing behavior (anodic oxidation reaction). As an intuitive phenomenon of the self-healing behavior, priority anodic oxidation phenomena was observed in a 210 nm thick hydrated AmAO film with a 65 nm thick Al electrode pad. The results suggested that self-healing behavior (anodic oxidation reaction) was occurring nearby the defect regions of the films during I–V test. It was an effective electrical self-healing method, which would be able to extend to many other simple and complex oxide dielectrics and various composite structures.