CMP compositions and methods for polishing nickel phosphorous surfaces
View Patent ↗Chemical mechanical polishing (CMP) compositions and methods for planarizing a nickel phosphorus (NiP) substrate are described. A NiP CMP method comprises abrading a surface of the substrate with a CMP composition. The CMP composition comprises a colloidal silica abrasive suspended in an aqueous carrier having a pH of less than 2, and containing a primary oxidizing agent comprising hydrogen peroxide, a secondary oxidizing agent comprising a metal ion capable of reversible oxidation and reduction in the presence of NiP and hydrogen peroxide, a chelating agent, and glycine. The chelating agent comprises two or three carboxylic acid substituents capable of chelating to the metal ion of the secondary oxidizing agent.
1. A chemical mechanical polishing (CMP) method for planarizing a nickel phosphorus (NiP) substrate, the method comprising abrading a surface of the substrate with a CMP composition; the CMP composition comprising a particulate abrasive suspended in an aqueous carrier having a pH of less than 1.5, and containing an oxidizing agent comprising hydrogen peroxide, a metal ion catalyst capable of reversible oxidation and reduction in the presence of NiP and the oxidizer, a catalyst stabilizing agent, and a Ni complexing agent, wherein the Ni complexing agent is glycine; wherein the catalyst stabilizing agent is malonic acid, and wherein the catalyst stabilizing agent is present in the CMP composition at a concentration of about 0.04 to about 0.2 wt % and present in a molar concentration of 2 to 5 times the metal ion molar concentration.
2. The method of claim 1 wherein the metal ion catalyst comprises at least one ion selected from the group consisting of ions of iron, cobalt, copper, europium, manganese, rhenium, molybdenum, iridium and tungsten.
3. The method of claim 1 wherein the metal ion catalyst is an iron ion.
4. The method of claim 3 wherein the iron ion comprises Fe 3+ .
5. The method of claim 1 wherein the catalyst stabilizing agent is selected from the group consisting of oxalic acid, citric acid, malonic acid, and a combination of two or more thereof; and the metal ion catalyst comprises Fe +3 .
6. The method of claim 1 wherein the particulate abrasive is colloidal silica.
7. The method of claim 6 wherein the colloidal silica is present in the CMP composition at a concentration of about 1 to about 20 percent by weight (wt %).
8. The method of claim 1 wherein the metal ion catalyst is present in the CMP composition at a concentration of about 50 to about 150 parts-per-million (ppm).
9. The method of claim 1 wherein the oxidizing agent is present in the CMP composition at a concentration of about 0.3 to about 1.8 wt %.
10. The method of claim 1 wherein Ni complexing agent is present in the CMP composition at a concentration of about 0.3 to about 1 wt %.
11. The method of claim 1 wherein the abrading is accomplished in conjunction with a polishing pad in a CMP polishing apparatus.