Effect of Corrosion Inhibitor(BTA) in Cu Slurry on Cu Polishing

Abstract

In this study, the effect of benzotriazole (BTA) in Cu slurry on Cu polishing behavior was investigated as functions of H2O2 and slurry pH. The addition of BTA to slurry effectively prevented Cu from being etched by forming a passivation layer of Cu–BTA regardless of pH and H2O2 concentration in the slurry. The passivation layer on the Cu wafer exhibited a contact angle of 50° in solution with BTA and H2O2. The dynamic etching rate, i.e., the Cu polishing rate using abrasive-free slurry, also decreased when BTA was added to the slurry at pH 2, 4, and 6. The removal rate of Cu in slurry without BTA was strongly dependent on H2O2 concentration and pH. In slurry with BTA, Cu–BTA on the Cu surface prevented the etching of Cu. At pH 2 and 4, the removal rates were lower in slurry with BTA than in slurry without BTA. However, slurries of pH 6 or higher with BTA showed higher removal rates at higher concentrations of H2O2 than 10%, which was explained by the thick passivating oxide layer formed at higher pH and H2O2 concentrations.