Some Tribological Aspects of Thin Film Copper During CMP

The effect of various process parameters like pressure, velocity and process consumable characteristics like pad properties and slurry chemistries on copper during Chemical Mechanical Planarization (CMP) process have been extensively researched. However, the thermal aspects of CMP have not been understood in detail. In this research, we present the effect of slurry temperature on the coefficient of friction and the resulting micro-structural changes in the copper material due to the polishing process. We also investigated the work hardening effect of polishing on copper thin film. From the results, it was found that temperature has an effect on the coefficient of friction but the effect of process parameters influences the effect of temperature. The effect of temperature on coefficient of friction is also dependent on the material of polishing pad. From XRD measurements more crystallinity was observed for the sample polished at 29°C as compared to other samples. The mechanical properties of copper investigated before and after CMP show improved mechanical properties with polishing. Significant change was observed among the mechanical properties of samples polished at different temperatures.Copyright © 2006 by ASME