Impurities induced localized corrosion between copper and tantalum nitride during chemical mechanical planarization

Abstract

Using chemical mechanical planarization, the reaction which causes the formation of localized defects between the interface between the copper (Cu) deposit and the tantalum nitride (TaN) barrier layer were studied. The experimental results of potentiodynamic polarization and secondary ion mass spectroscopy demonstrate that galvanic corrosion was not the dominant factor for such localized defects in our system, most impurities, such as carbon (C) and chloride ion (Cl-), aggregated near the interface between Cu deposit and TaN barrier layer. As a result, the correlation between localized defects at the CuTaN interface and the distribution of impurities is proposed herein. © 2006 The Electrochemical Society.