SILICA-BASED SLURRY COMPOSITIONS CONTAINING HIGH MOLECULAR WEIGHT POLYMERS FOR USE IN CMP OF DIELECTRICS

The invention provides a chemical-mechanical polishing composition comprising: (a) about 3.0 wt. % to about 10 wt. % silica abrasive; (b) an anionic polymer having a weight average molecular weight of about 400 kDa to about 7000 kDa; and (c) water, wherein the polishing composition has a viscosity of at least about 1 cPs, a ratio of viscosity (cPs) to wt. % of silica abrasive of about 0.2 cPs/wt. % to about 1.5 cPs/wt. %, and a pH of about 9 to about 12. The invention additional provides a chemical-mechanical polishing composition comprising: (a) about 3.0 wt. % to about 10 wt. % silica abrasive; (b) a nonionicpolymer having a weight average molecular weight of about 300 kDa to about 7000 kDa; and (c) water, wherein the polishing composition has a viscosity of at least about 2 cPs, and a pH of about 9 to about 12. The invention also provides a method of chemically-mechanically polishing a substrate, especially a substrate comprising silicon oxide, silicon nitride, polysilicon, or combinations thereof, using said compositions.