Patent ID: 7314823

Claim:
A method of chemically mechanically polishing comprising: A) providing a semiconductor wafer substrate having a surface to be polished comprising tungsten and a dielectric material; B) providing an aqueous composition comprising: 1) a first oxidizer selected from the group consisting of ammonium persulfate, hydroxylamine or salt thereof, periodic acid, hydrogen peroxide, an indirect source of hydrogen peroxide, or a urea hydrogen peroxide complex; and 2) a second oxidizer different than the first oxidizer, wherein the second oxidizer is not a product of a reaction of the first oxidizer with the composition, and the second oxidizer is not nitric acid; and C) contacting the surface with an abrasive and with said aqueous composition comprising said first and second oxidizers, thereby polishing tungsten from the surface of the semiconductor wafer substrate, wherein the polishing rate exhibits a synergistically increased tungsten removal rate compared with the removal rates achieved by polishing with a slurry having only the first oxidizer and polishing with a slurry having only the second oxidizer, and wherein the pH of the aqueous composition is in the range of 5.5 to 9.