Polishing method

A method for chemically and mechanically polishing an object to form wiring for a semiconductor device, the object including an insulator layer having a trench, a barrier layer provided on the insulator layer, and a conductor layer provided on the barrier layer, wherein the barrier layer and the conductor layer each have an outside portion located outside the trench and an inside portion located inside the trench, the method comprising:

• removing part of the outside portion of the conductor layer through chemical and mechanical polishing to expose an upper surface of the barrier layer;
• and
• removing the remaining part of the outside portion of the conductor layer and the outside portion of the barrier layer through chemical and mechanical polishing to expose an upper surface of the insulator layer after removing part of the outside portion of the conductor layer,
• wherein said removing part of the outside portion of the conductor layer includes:
• chemically and mechanically polishing an upper surface of the object using a first polishing composition containing a film forming agent;
• washing the upper surface of the object that has been chemically and mechanically polished, thereby removing a protective film formed on the upper surface of the conductor layer by the film forming agent in the first polishing composition;
• and
• chemically and mechanically polishing the upper surface of the washed object using a second polishing composition containing a film forming agent.