Abstract
All pad conditioners used for CMP today are made by attaching discrete diamond grits on a flat substrate. Polycrystalline diamond (PCD) was wire-EDM cut to form blades with different designs of cutting tips. These blades were assembled to form the so-called ultimate diamond disk (UDD). The pad asperities formed with UDD were compared with conventional diamond disks. It was confirmed that UDD dressed pad asperities were more uniform than that for polishing IC wafers today. The UDD dressed pads were also used to polish tungsten (W) IC layer deposited on 300 mm wafers. As the surface of PCD contains only merged diamond grains that are corrosion immune, UDD was dressing in-situ, by immersing in the acid slurry. The wafer uniformity so polished was comparable to that of ex-situ CMP pad dressing with metallized diamond disks. The in-situ dressing can boost the CMP throughput by deglazing the pad in real time while the wafer is being polished. After 15 hours, the wafer profiles for this in-situ dressing were sustained without decay.
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