Laboratory for Manufacturing and Sustainability

Acoustic emission (AE) is used as a technique to monitor and characterize surface interactions between wafer and pad in a chemical-mechanical planarization (CMP) process for copper. A significant variation in in-situ AE signal was observed during controlled variation of the slurry composition, demonstrating the sensitivity of AE to the unique surface reactions taking place. Two different levels of AE were observed; a high root-mean-square (RMS) signal when polishing H2O2 treated copper, and a low RMS signal when polishing bare copper. The rate of change in the AE signal was also tied to variations in species concentration and pH in slurry.