The role of complexing agents in the chemical-mechanical planarization of copper

The present dissertation study investigates the effect of complexing agents on the electrochemical dissolution and chemical mechanical planarization of copper, with the aim of improving our understanding of the mechanisms responsible for planarization and material removal in copper chemical mechanical planarization (CMP).; In the first stage of the study, the electrochemistry of copper was examined in aqueous solutions of several complexing agents, including glycine, ethylenediamine and EDTA. The effect of the complexing agents on copper dissolution was delineated by comparing the electrochemical behavior of copper in solutions with and without complexing agents.; The effects of glycine and EDTA on copper CMP were examined using the polishing behavior of copper in the absence of complexing agents as the baseline. Regardless of the nature of the chemical environment, in-situ electrochemical studies during polishing revealed no significant changes in the polarization behavior in regions of active dissolution, other than modest increases in current density that probably reflected enhanced mass transport.; It was found that under conditions that give passivity, glycine would enhance the planarization efficiency as it promotes higher material removal from protruding regions. The copper dissolution and polishing behavior was also examined in glycine solutions or slurries containing H₂O ₂. Passivation behavior was observed at pH4 and 9 (neither of these is neutral) in 10−2 M glycine above certain H₂O ₂ concentrations, suggesting the formation of higher copper oxides such as Cu₂O₃ and CuO₂.; The effect of electrochemical polarization on the copper removal rates during polishing was also investigated in EDTA slurries. The experimental results demonstrated synergistic interactions between the electrochemical and mechanical forces in the copper CMP process, indicating that enhanced material removal and planarization could only be achieved when the electrochemical and mechanical components act together in a favorable manner. (Abstract shortened by UMI.)...