Ruthenium CMP compositions and methods

A chemical-mechanical polishing (CMP) method for selectively removing ruthenium from the surface of a substrate in preference to silicon dioxide, the method comprising the steps of

• (a) contacting a surface of a substrate comprising ruthenium and silicon dioxide with a polishing pad and an aqueous CMP composition in the presence of an oxidizing agent;
• and
• (b) causing relative motion between the substrate and the polishing pad while maintaining a portion of the CMP composition and oxidizing agent in contact with the surface between the pad and the substrate for a period of time sufficient to abrade at least a portion of the ruthenium present in the substrate from the surface;
• wherein the CMP composition contains a particulate abrasive selected from the group consisting of alumina, titania, and a combination thereof;
• the particulate abrasive being suspended in an aqueous carrier containing a ruthenium-coordinating oxidized nitrogen ligand (N—O ligand), the N—O ligand comprising a nitroxide compound;
• wherein, in the presence of the oxidizing agent, the N—O ligand is capable of preventing the deposition of ruthenium species having an oxidation state of IV or higher on the surface of the substrate, and concomitantly is capable of forming a soluble Ru(II) N—O coordination complex with oxidized ruthenium formed during CMP of the substrate.

A chemical-mechanical polishing (CMP) method for selectively removing dioxide from the surface of a substrate in preference to ruthenium, the method comprising the steps of:

• (a) contacting a surface of a substrate comprising ruthenium and silicon dioxide with a polishing pad and an aqueous CMP composition in the presence of an oxidizing agent;
• and
• (b) causing relative motion between the substrate and the polishing pad while maintaining a portion of the CMP composition and the oxidizing agent in contact with the surface between the pad and the substrate for a period of time sufficient to abrade at least a portion of the ruthenium present in the substrate from the surface;
• wherein the CMP composition contains a particulate abrasive comprising colloidal silica suspended in an aqueous carrier containing a ruthenium-coordinating oxidized nitrogen ligand (N—O ligand), the N—O ligand comprising a nitroxide compound;
• and, in the presence of the oxidizing agent, the N—O ligand is capable of preventing the deposition of ruthenium species having an oxidation state of IV or higher on the surface of the substrate, and concomitantly is capable of forthing a soluble Ru(II) N—O coordination complex with oxidized ruthenium formed during CMP of the substrate.