A fundamental study was undertaken to evaluate the usefulness of a sulfonic acid-based chemical system for the removal of tantalum under electrochemical mechanical planarization conditions. Tantalum as well as copper samples were polished at low pressures (similar to 0.5 psi) under galvanostatic conditions in dihydroxy benzene sulfonic acid (DBSA) solutions maintained at different pH values. At a current density of 0.5 mA/cm(2) and pH 10, tantalum removal rate of similar to 200 angstrom/min with a 1: 1 selectivity to copper has been obtained in 0.3 M DBSA solutions containing 1.2 M H2O2. The presence of a small amount (similar to 0.1%) of colloidal silica particles is required to obtain good removal rates. (c) 2008 The Electrochemical Society.