Study of oxidation process of Cr/Cu/Cr thin film electrodes

Understanding the oxidation process of Cr/Cu/Cr laminated thin film electrode is important for developing new oxidation-resistant electrodes. By studying the evolution of crystal structure, morphology and electric resistivity of Cr/Cu/Cr thin films and electrodes that were post-annealed at different temperatures, the oxidation mechanism and process of Cr/Cu/Cr electrode were proposed. Copper is first oxidized into Cu2O at low temperatures (<310 °C), and converts to CuO phase at higher temperatures. Two pathways for oxygen diffusion were identified: diffusion from the protective Cr layer, and diffusion from the sidewall of electrode, of which the latter one leads to total oxidation of copper interlayer at high temperatures (>310 °C). As a result, the passivation of Cu metal at electrode sidewalls is crucial in reducing oxidation of Cr/Cu/Cr electrodes or designing new copper-containing oxidation-resistant electrodes.