The invention provides a chemical-mechanical polishing composition comprising a) surface-modified colloidal silica particles, comprising a negatively-charged group on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about −5 mV to about −35 mV at a pH of about 3, b) an iron compound, c) a stabilizing agent, d) a corrosion inhibitor, and e) an aqueous carrier. The invention also provides a method suitable for polishing a substrate.