Atmospheric Corrosion of Electroplated Cu Thin Film in Moist Oxygen Environment

Abstract

Atmospheric corrosion of electrodeposited Cu thin film in water vapour with oxygen was studied using a quartz crystal microbalance. The adsorption of water with N2 carrier gas without oxygen was reversible and roughly proportional to the relative humidity. The corrosion weight gain exhibited an initial linear rate law region followed by a parabolic rate law one. The rate for both regions was influenced by both relative humidity and O2 partial pressure. The electrochemical oxidation process of Cu might occur under an adsorbed water layer. It is considered that the water adsorbed as clusters and corrosion progressed under the water cluster, the thickness and surface coverage of which varied with relative humidity. The rough estimation revealed that the kinetic constants for both first linear rate and parabolic rate laws is proportional to the ratio of surface coverage by water cluster. However, the rate constant is independent of R.H., if normalized by the area of water clusters.