Electrochemical behavior of aluminum during chemical mechanical polishing in phosphoric acid base slurry

The electrochemical behavior of aluminum in chemical mechanical polishing ( CMP) slurry was investigated using potentiodynamic polarization measurement and electrochemical impedance spectroscopy. The slurry used was mainly com posed of phosphoric acid, citric acid, and 50 nm Al2O3 particles. The effec ts of slurry flow and contact pressure on the electrochemical behavior of A l went explored. The roles of chemical and mechanical interaction on the re moval rate of Al during CMP a ere also attempted. The results showed that t he corrosion potential decreased with increasing contact pressure and plate n rotating speed. The dissolution rate, which was in reversing proportion t o the polarization resistance, also increased with increasing the contact p ressure and platen rotating speed. The repeated passivation, film breakdown due to mechanical abrasion, and metal dissolution steps took place during the simulating CMP process. The passive Film formed in the testing slurry c onsisted of Al2O3, Al(OH)(3), and AlPO4. (C) 2000 The Electrochemical Socie ty. S0013-4651(99)03-073-6. All rights reserved.