CHEMICAL-MECHANICAL POLISHING SLURRY FORMULATION AND METHOD FOR TUNGSTEN AND TITANIUM THIN FILMS

摘要

A polishing slurry composition and its method of making for planarization of silicon semiconductor wafers by chemical mechanical polishing of the wafer. A slurry formulation utilizing a ferric salt tungsten oxidizer, an ammonium persulfate titanium oxidizer, a fatty acid suspension agent, alumina particles with a small diameter and tight diameter range, coated with a solubility coating, and a chemical stabilizer, provides high tungsten and titanium polish rates with high selectivity to silicon dioxide, and good oxide defectivity for use in tungsten local interconnect applications. A method for making a tungsten slurry includes first thoroughly blending small diameter alumina particles with a tight diameter range in an aqueous concentrate with a suspension agent, then mixing with water and oxidizers. Ferric salt tungsten slurries made by this method provide excellent tungsten polish characteristics for via plug and local interconnect applications.