Surface modified colloidal abrasives, including stable bimetallic surface coated silica sols for chemical mechanical planarization
View Patent ↗A composition and an associated method for chemical mechanical planarization (or other polishing) are described. The composition includes a surface-modified abrasive modified with at least one stabilizer and at least one catalyst differing from the at least one stabilizer. The composition can further include a medium containing the abrasive and an oxidizing agent (e.g., hydrogen peroxide), wherein the at least one catalyst is adapted to catalyze oxidation of a substrate by the oxidizing agent. Preferably, the abrasive is alumina, titania, zirconia, germania, silica, ceria and/or mixtures thereof, the stabilizer is B, W and/or Al, and the catalyst is Cu, Fe, Mn, Ti, W and/or V. Both the stabilizer and the catalyst are immobilized on the abrasive surface. The method includes applying the composition to a substrate to be polished, such as substrates containing W, Cu and/or dielectrics.
1. A method for polishing a surface of a substrate, said method comprising applying to a surface of a substrate a polishing composition, said polishing composition comprising an abrasive having a surface on which at least one stabilizer and at least one catalyst are bonded,
wherein the stabilizer comprises Al, B, or tungstate,
wherein the catalyst is a metal salt comprising Fe or Cu, and
wherein the substrate comprises at least one member selected from the group consisting of W, Ti, TiN, Cu, Ta, TaN and SiO2.
2. The method of claim 1 , wherein the substrate further comprises a material having a dielectric constant of less than 2.8.
3. The method of claim 1 , wherein the composition further comprises:
an oxidizing agent; and
a medium in which the abrasive and the oxidizing agent are contained.
4. The method of claim 3 , wherein the abrasive is a member selected from the group consisting of alumina, titania, zirconia, germania, silica, ceria and mixtures thereof, and the substrate comprises at least one member selected from the group consisting of W, Ti, TiN, Cu, Ta, TaN and SiO2.
5. The method of claim 4 , further comprising:
applying the composition to a polishing pad; and applying the polishing pad to the surface of the substrate to planarize the substrate.
6. The method of claim 5 , wherein the substrate comprises W and a dielectric material, and a selectivity for removal of W relative to removal of the dielectric material from said substrate is at least 10:1.
7. The method of claim 5 , wherein the abrasive is silica, the at least one stabilizer comprises B, the at least one catalyst comprises Fe and the oxidizing agent is hydrogen peroxide.
8. The method of claim 5 , wherein the abrasive is silica, the at least one stabilizer B, the at least one catalyst comprises Cu and the oxidizing agent is hydrogen. peroxide.
9. The method of claim 5 , wherein the abrasive is silica, the at least one stabilizer comprises tungstate, the at least one catalyst comprises Fe and the oxidizing agent is hydrogen peroxide.
10. The method of claim 5 , wherein the composition is free of soluble metal catalysts.
11. A method for chemical mechanical polishing of a surface of a semiconductor substrate, said method comprising applying to a surface of a substrate a polishing composition,
wherein the substrate comprises at least one member selected from the group consisting of W, Ti, TiN, Cu, Ta, TaN and SiO 2 , the polishing composition comprises an oxidizing agent admixed into a precursor composition comprising an abrasive, water, and boric acid,
wherein the abrasive is a member selected from the group consisting of alumina, titania, zirconia, germania, silica, ceria and mixtures thereof; and
wherein at least a portion of the boric acid is bound to the abrasive.
12. The method of claim 11 wherein the polishing composition comprises about 2.27% by weight silica, about 0.05% by weight boric acid, about 2.6% by weight periodic acid, about 0.11% by weight nonionic surfactant, ammonium hydroxide in an amount sufficient to adjust the pH to between 3.5 and 4, and a balance water.
13. The method of claim 11 wherein the polishing composition further comprises ferric ions.