The inventive method of polishing a silicon-containing dielectric layer involves the use of a chemical-mechanical polishing system comprising (a) an inorganic abrasive, (b) a polishing additive, and (c) a liquid carrier, wherein the polishing composition has a pH of about 4 to about 6. The inventive chemical-mechanical polishing system comprises (a) ceria, (b) a polishing additive, and (c) a liquid carrier, wherein the polishing system has a pH of about 4 to about 6.