Electrochemical Investigation of Alumina Thin Films for Electronic Packaging

Thin films of alumina processed by atomic layer deposition (ALD) were electrochemically investigated by impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) as well as material analysis (SEM, FTIR). The resulting films are almost free of water and organic residues originated from the ALD process. Nevertheless, the electrochemical results show significant deviation from the expected properties and behavior. The ALD films show a significant reactivity in aqueous electrolytes, indicating electron conductivity under cathodic and corrosion under anodic polarization. The thinner the film thickness the higher the electrochemical activity. In the thicker layers, no defects were detected microscopically; however, the incorporation of copper into the alumina oxide layer was confirmed.