Corrosion susceptibility of thin-film metallizations

Anodic DC polarization and AC electrochemical impedance-spectroscopy techniques were applied to obtain a better understanding of the corrosion process in Al and Al-Cu thin-film metallizations. The oxide-layer resistance, oxide-layer/double-layer capacitance, and anodic-polarization scans of Al and Al-Co thin-film metallizations which have been sputtered onto partially oxidized silicon substrates are correlated to oxide-layer thickness, Cu distribution, and oxide-layer integrity. Auger electron spectroscopy was employed to quantify oxide-layer thickness and its apparent influence on impedance-spectroscopy response, while scanning electron microscopy was used to observe the type of corrosion attack. The results discussed are compared with results previously obtained on bulk Al-Co alloys.<>