Frictional characterization of chemical-mechanical polishing pad surface and diamond conditioner wear

We evaluated a contact metrology instrument used in chemical-mechanical polishing (CMP) systems for high-volume manufacture and examined in situ coefficient of friction (COF) monitoring to identify the tribology of CMP, and subsequently to determine the useful lifespan of consumables. The results showed that the direct measurement of the wear of the pad allowed for an accurate determination of both pad thickness and the ideal time to replace the pad and conditioner disk based on pad wear rate. We also presented a clear correlation between the working grid area of the conditioner disk and the tribological behavior of the pad break-in procedure, leading to the result showing that the variation in tungsten film removal rate decreased as the working grid density of the conditioner disk increased. This study has proven the effectiveness of measuring friction force for better CMP control.