Surface treated abrasive particles for tungsten buff applications

A chemical-mechanical polishing composition comprising:

• (a) an alumina abrasive, wherein the abrasive is positively charged at the pH of the polishing composition prior to surface coating, wherein the alumina is surface-coated with a copolymer comprising a combination of sulfonic acid monomeric units and carboxylic acid monomeric units, or wherein the abrasive is surface-coated with a copolymer comprising a combination of sulfonic acid monomeric units and phosphonic acid monomeric units,
• (b) an oxidizing agent, wherein the oxidizing agent comprises hydrogen peroxide and about 5 ppm to about 500 ppm ferric nitrate,
• (c) an organic phosphonic acid, wherein the organic phosphonic acid is selected from 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methyl phosphonosuccinic acid, and combinations thereof, and
• (d) water,
• wherein the polishing composition has a pH of about 2 to about 5.

A method of chemically mechanically polishing a substrate comprising:

• (i) providing a substrate, wherein the substrate comprises at least one layer of tungsten or cobalt and at least one layer of silicon oxide, and wherein at least a portion of the tungsten or cobalt and at least a portion of the silicon oxide is abraded to polish the substrate,
• (ii) providing a polishing pad,
• (iii) providing a chemical-mechanical polishing composition comprising:
• (a) an abrasive selected from the group consisting of alumina, ceria, titania, zirconia, and combinations thereof, wherein the abrasive is positively charged at the pH of the polishing composition prior to surface coating, wherein the abrasive is surface-coated with a copolymer comprising a combination of sulfonic acid monomeric units and carboxylic acid monomeric units, or wherein the abrasive is surface-coated with a copolymer comprising a combination of sulfonic acid monomeric units and phosphonic acid monomeric units,
• (b) an oxidizing agent, wherein the oxidizing agent comprises hydrogen peroxide and about 5 ppm to about 500 ppm ferric nitrate,
• and
• (c) water,
• wherein the polishing composition has a pH of about 2 to about 5,
• (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition, and
• (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.