Effect of Complexing Agent Choices on Dishing Control Level and the Shelf Life in Copper CMP Slurry

There has been lot of work going on reducing dishing without benzotriazole (BTA) because it can lead to organic debris and other defects during the chemical mechanical planarization (CMP) although being an effective dissolution inhibitor on dishing elimination. Slurry destabilization problems also have to be closely monitored because it can cause surface defects and changes in the material removal due to particle agglomeration and the chemical degradation. In this study, FA/O chelating agent, a unique alkaline organic macromolecule, yielded a lower dishing level under the condition of no BTA compared with glycine, which allows for a substantial reduction in the use of BTA. The dissolution rate, polish rate and changes in the in-situ open circuit potential (OCP) were performed to elucidate the planarization mechanism and how the use of carcinogenic BTA can be reduced. It was also observed that the FA/O based slurry had a shelf life of no more than 7 days and the root cause was the oxidation reduction reaction between FA/O chelating agent and H2O2 rather than the self-decomposition of the hydrogen peroxide.