Patent ID: 7563716

Claim:
A polishing method for removing at least part of a metal film on an insulating film, comprising: providing a semiconductor substrate with the insulating film having an opening for a plug and being formed over the semiconductor substrate, the metal film being provided in the opening; and chemically mechanically polishing the metal film on the insulating film using a polishing solution which additionally has included therein less than 1 wt % of a polishing abrasive, and includes an oxidizer, a substance which renders an oxide water-soluble, and a surfactant, said solution having a pH and oxidation-reduction potential in the domain of corrosion of said metal film, said chemical mechanical polishing leaving a plug of said metal film in said opening; wherein the surfactant is mechanically rubbed out from a surface of the metal film and a metal oxide is made soluble to a substance for polishing the metal film, and wherein said metal film is one selected from the group consisting of a tungsten film, a tungsten alloy film, and a tungsten compound film having tungsten as its principal component.