Effect of Dissolved Oxygen on Removal of Benzotriazole from Co during a Post-Co CMP Cleaning

Abstract

A systematic study of the adsorption of benzotriazole on Co surface and its removal in aqueous solutions was carried out for post-CMP cleaning application. Static etch rate (SER) measurements and electrochemical impedance spectroscopy (EIS) were employed. The experimental results show that BTA adsorbed well on Co surface when it exposed to BTA solution at neutral and alkaline pH. BTA did not adsorb due to active Co dissolution at acidic pH. The effect of dissolved oxygen (DO) concentration in de-ionized (DI) water on the removal of Co-BTA complex layer was investigated. At the DI water rinse process after BTA treatment, Co-BTA layer was maintained on Co surface when DO concentration of DI water was low. Interestingly, BTA was removed by DI water with high DO concentration.