Particle innovations in copper CMP slurry development - impact of hydrophilicity, hardness, and functionality

Surface planarity is of paramount importance in fabricating advanced semiconductor devices at wafer level with minimum feature size smaller than 0.25 μm. Chemical mechanical polishing (CMP) is the most viable approach and has become an enabling technology to address the planarity issues. With the integration of copper as interconnect and low k materials as dielectric, the CMP community is facing an ever increasing demand on reducing detectivity without scarifying production throughput (Kawahashi and Hattori, 2001). Key issues in CMP today include reduction of surface detectivity and enhancement of planarization efficiency. More specifically, the polished surface should be free of defects such as scratches, pits, corrosion spots, and residue particles (Kondo et al., 2000). To accomplish these goals, we have investigated a wide range of pathways including the use of unique abrasives with varying degree of hardness, hydrophilicity, and functionality such as nano diamond, plate like boron nitride, functionalized silica, encapsulating vesicles, and micelles. In this presentation, some fundamental aspects of the CMP process were given first. Several academic and industrial examples were used to illustrate the issues and challenges during the implementation of various slurry designs into the CMP processes.