Key issues in CMP today include reduction of surface defectivity and enhancement of planarization efficiency. More specifically, the polished surface should be free of defects such as scratches, pits, corrosion spots, trench copper loss, and residue particles. For copper/low k CMP, one of the most promising strategies to accomplishing these goals is an Abrasive-Free Process (AFP). By eliminating abrasive particles from the process, either free or fixed to the pad, it has been anticipated and realized that defects such as severe scratching, particle contamination and slurry instability via particle aggregation or settling will be significantly reduced. In addition, with proper formulation, an abrasive free process can also yield an excellent over polishing window and desired step function of pressure for material removal rate. The potential advantage of this non-Prestonian behavior at low down force provides the abrasive free system an edge for copper low k integration. In this study, some designing principles for an abrasive free system will be first presented. The potential advantages of a supramolecular design for the low k integration will be illustrated. The CMP performance on a set of testing blanket and patterned wafers will be discussed.
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