Electrochemical aspects of copper chemical mechanical planarization (CMP) in peroxide based slurries containing BTA and glycine

The electrochemical behavior of copper was studied in Na2SO4 solutions (pH 4), containing peroxide, benzotriasol (BTA) and glycine. The effect of BTA was initially evaluated in sulfate solution without peroxide and it was established that once BTA is present, copper undergoes a strong passivation process in a potential range below 0.2 V (SCE). At potentials above 0.2 V the protective layer of BTA is destroyed and copper suffers from localized corrosion attacks. Positive potentiodynamic sweep of the potential resulted in increase of anodic currents at potentials above 0.2 V and hysteresis appearance resulting in the formation of wide and deep pits on the surface of the copper substrate. The addition of H2O2 to BTA containing solutions resulted in a rapid increase of OCP to values significantly higher than 0.2 V, leading to initiation of copper localized corrosion processes. (C) 2003 Elsevier Ltd. All rights reserved.