Theoretical validation of inhibition mechanisms of benzotriazole with copper and cobalt for CMP and post-CMP cleaning applications

Abstract

Corrosion inhibitors are essential additives for metal CMP (chemical mechanical planarization) slurries and post-metal CMP cleaning solutions. They effectively address corrosion issues by forming complexes with the metal surfaces, but they sometimes cause organic defects. Hence understanding the interactions between the corrosion inhibitor and metal surface is important. In this study, the formation and stability of the Cu/Co-benzotriazole (BTA) complex on Cu and Co surfaces were experimentally investigated, and the experimental results were theoretically explained through computational calculations. The characteristics of the Cu/Co-BTA complex layer on Cu and Co surfaces were analyzed using sequential EIS, AFM, and contact angle measurements. A Cu/Co-BTA complex layer was formed when the Cu and Co surfaces were exposed to the BTA solution. After a de-ionized (DI) water rinse, the Cu-BTA complex on the Cu surface remained a stable film, whereas the Co-BTA complex layer on the Co surface was removed. Computational calculations provided BTA binding energies, d-band center, and electron charge transfer between BTA and metal surfaces. The BTA binding energy and electron charge transfer to the Co(001) surface were lower than that of Cu(111), which supports the removal of the Co-BTA complex by a DI water rinse in the experimental results.