Chemical mechanical polishing method for cobalt with high cobalt removal rates and reduced cobalt corrosion

A method of chemical mechanical polishing cobalt, comprising:

• providing a substrate comprising cobalt;
• providing a chemical mechanical polishing composition, consisting of, as initial components:
• water;
• an oxidizing agent;
• 0.3 wt % to 1 wt % aspartic acid or salts thereof;
• colloidal silica abrasive particles;
• and
• a phosphonic acid or salt thereof having a formula:
• wherein R is a linear alkyl group of twelve to eighteen carbon atoms, and wherein the phosphonic acid or salt thereof is in amounts of 0.0001 wt % to 0.001 wt %;
• and
• optionally a biocide;
• optionally, a pH adjusting agent selected from the group consisting of potassium hydroxide and nitric acid;
• optionally, a surfactant;
• and
• wherein a pH of the chemical mechanical polishing composition is from 7-11;
• providing a chemical mechanical polishing pad, having a polishing surface;
• creating dynamic contact at an interface between the chemical mechanical polishing pad and the substrate;
• and
• dispensing the chemical mechanical polishing composition onto the polishing surface of the chemical mechanical polishing pad at or near the interface between the chemical mechanical polishing pad and the substrate to remove at least some of the cobalt.