Defect reduction with CMP pad dressing optimization

CMP is regarded as a process to remove material from wafer surface. And lots of mixture will be created from polishing interface. Consumables, such like pad, retainer ring, dresser and membrane will be consumed during polishing. Furthermore, abrasive, slurry chemicals and wafer surface material will have some specific interaction through well designed chemistry, which produced lots of by-products. These un-expected pollutants from consumable consumed and chemical reactions during polishing will generate defects on wafer surface, such like scratch, pits or others. This study introduces an advanced opinion to ease defect generated. We found pad dressing parameter is a highly correlation factor to post CMP defects. Over dressing condition will shorten pad life time and also create more particles in the polishing interface to cause defects on the wafer. Under dressing condition will get an unstable removal rate and uniformity through pad life time. We had found out a sweet spot for defects reductions with BSL (baseline) RR (removal rate) and uniformity retained with dressing recipe optimized.