First Principle Study of the Adsorption Behavior of 1,2,4-Triazole on Defective Copper Surface

Chemical mechanical polishing (CMP) is widely used in chip manufacturing processes including metal interconnection, wafer-to-wafer hybrid bonding and throughsilicon-via technologies to planarize surfaces and remedy defects. Its planarization and defect-remedy abilities are highly associated with the inhibitors in the CMP slurry and their interaction with metal surface. Though density functional theory (DFT) calculation has been proven effective in unravelling the adsorption mechanism on the atomic scale, previous work mainly focused on the inhibitors' interaction with preface metal surface while defects are actually common in copper surfaces. In this contribution, the adsorption behaviors of the classic inhibitor 1,2,4-triazole (TAZ) on copper (1 1 1), (1 0 0), (1 1 0) faces and the defective (1 1 1) face were studies based on DFT. Results showed that the reactive centers of TAZ were N(3) and N(5) atoms. The most stable adsorption geometry for TAZ on the three perfect surfaces were all vertical configurations through N(5) and copper atoms. Comparatively, TAZ absorbed on defective copper (1 1 1) with a tilt configuration through both N(3) and N(5) atoms with a much higher adsorption energy. In addition, the charge transference and bonding characteristics were also studied. These results proved inhibitors' stronger protection in defective or concave places on copper surface, providing profound explanations for inhibitors' ability to reduce defects.