Effect of applied potential on the chemical mechanical polishing of aluminum in phosphoric acid base slurry

The electrochemical behavior of Al in phosphoric acid base slurry was inves tigated under chemical mechanical polishing (CMP) condition. The effect of applied potential on the CMP metal removal rate was also evaluated. The res ults from potentiodynamic polarization curve measurements indicated that a contact pressure in the range of 3 to 9 psi greatly modified the passivatio n behavior of Al in 5 vol % H3PO4 + 0.5 M citric acid + 5 wt % Al2O3 slurry by a decrease in corrosion potential and an increase in passive current de nsity. The experimental results also showed that CMP removal rate strongly depended on the contact pressure and potential applied. The potential depen dence behavior of the removal rate could be divided into three regions depe nding on the direction of polarization and the magnitude of potential appli ed. The results of electrochemical impedance spectroscopy and Auger electro n spectroscopy examinations showed that passive film formation on Al in the resting slurry was affected by the applied potential, which in term caused a change in the relative contribution of the corrosion and mechanical abra sion to the total removal rate of Al. (C) 2000 The Electrochemical Society. S0013-4651(99)07-090-1. All rights reserved.