Tribological behavior of copper chemical-mechanical polishing

This work represents the findings using tribological investigation into the mechanism of the contact-polishing process during chemical-mechanical polishing (CMP) of copper. In order to understand the mechanical impact in CMP, this work simulates the Cu CMP using a laboratory model system. By comparing experimentally determined values, the friction coefficient with a series designed conditions was evaluated. We also at the first time estimated the lubricating behavior of Cu CMP. Experimental evidence proves that the Cu CMP performs as a lubricating system. In the conditions investigated, the boundary lubrication and elasto-hydrodynamic lubrication regimes were reached. Results indicate that measured friction is sensitive to chemical additives and surface chemistry. This is visible when polishing with DI water, hydroperoxide, acidic and basic slurries. Polishing mechanisms is further discussed here with the SEM analysis.