Mixed-abrasive polishing composition and method for using the same
View Patent ↗The invention provides a polishing composition comprising (i) an abrasive comprising (a) about 5 to about 45 wt. % of first abrasive particles having a Mohs' hardness of about 8 or more, (b) about 1 to about 45 wt. % of second abrasive particles having a three-dimensional structure comprising aggregates of smaller primary particles, and (c) about 10 to about 90 wt. % of third abrasive particles comprising silica, and (ii) a liquid carrier. The invention also provides a method of polishing a substrate, which method comprises the steps of (i) providing the above-described polishing composition, (ii) providing a substrate having a surface, and (iii) abrading at least a portion of the substrate surface with the polishing composition to polish the substrate.
1. A polishing composition comprising:
(i) an abrasive comprising (a) about 5 to about 45 wt. % of first abrasive particles having a Mohs' hardness of about 8 or more, (b) about 1 to about 45 wt. % of second abrasive particles having a three-dimensional structure comprising aggregates of smaller primary particles, and (c) about 10 to about 90 wt. % of third abrasive particles comprising silica, and
(ii) a liquid carrier.
2. The polishing composition of claim 1 , wherein the first abrasive particles are α-alumina particles.
3. The polishing composition of claim 1 , wherein the second abrasive particles are fumed alumina particles.
4. The polishing composition of claim 1 , wherein the silica is colloidal silica.
5. The polishing composition of claim 1 , wherein the liquid carrier comprises water.
6. The polishing composition of claim 1 , wherein the abrasive is present in an amount of about 0.5 to about 20 wt. % based on the total weight of the polishing composition.
7. The polishing composition of claim 6 , wherein the abrasive is present in an amount of about 1 to about 6 wt. % based on the total weight of the polishing composition.
8. The polishing composition of claim 1 , wherein the abrasive comprises (a) about 15 to about 40 wt. % of the first abrasive particles, (b) about 15 to about 40 wt. % of the second abrasive particles, and (c) about 20 to about 70 wt. % of the third abrasive particles.
9. The polishing composition of claim 1 , wherein the abrasive comprises (a) about 15 to about 25 wt. % of the first abrasive particles, (b) about 1 to about 10 wt. % of the second abrasive particles, and (c) about 70 to about 80 wt. % of the third abrasive particles.
10. The polishing composition of claim 1 , wherein the first abrasive particles have a mean particle size of about 1 μm or less.
11. The polishing composition of claim 10 , wherein the first abrasive particles have a mean particle size of about 400 nm or less.
12. The polishing composition of claim 1 , wherein the second abrasive particles have a mean aggregate particle size of about 200 nm or less.
13. The polishing composition of claim 1 , wherein the third abrasive particles have a mean particle size of about 150 nm or less.
14. The polishing composition of claim 1 , wherein the polishing composition further comprises an oxidizing agent.
15. The polishing composition of claim 14 , wherein the oxidizing agent comprises hydrogen peroxide.
16. The polishing composition of claim 1 , wherein the polishing composition further comprises an acid.
17. The polishing composition of claim 16 , wherein the acid is an organic acid.
18. The polishing composition of claim 17 , wherein the organic acid is selected from the group consisting of oxalic acid, malonic acid, tartaric acid, acetic acid, lactic acid, propionic acid, phthalic acid, benzoic acid, citric acid, succinic acid, salts thereof, and combinations thereof.
19. The polishing composition of claim 1 , wherein the polishing composition has a pH of about 1 to about 4.
20. A method of polishing a substrate, which method comprises the steps of:
(i) providing a polishing composition comprising:
(a) an abrasive comprising (I) about 5 to about 45 wt. % of first abrasive particles having a Mohs' hardness of about 8 or more, (II) about 1 to about 45 wt. % of second abrasive particles having a three-dimensional structure comprising aggregates of smaller primary particles, and (III) about 10 to about 90 wt. % of third abrasive particles comprising silica, and
(b) a liquid carrier,
(ii) providing a substrate having a surface, and
(iii) abrading at least a portion of the substrate surface with the polishing composition to polish the substrate.
21. The method of claim 20 , wherein the first abrasive particles are α-alumina particles.
22. The method of claim 20 , wherein the second abrasive particles are fumed alumina particles.
23. The method of claim 20 , wherein the silica is colloidal silica.
24. The method of claim 20 , wherein the liquid carrier comprises water.
25. The method of claim 20 , wherein the abrasive is present in an amount of about 0.5 to about 20 wt. % based on the total weight of the polishing composition.
26. The method of claim 25 , wherein the abrasive is present in an amount of about 1 to about 6 wt. % based on the total weight of the polishing composition.
27. The method of claim 20 , wherein the abrasive comprises (a) about 15 to about 40 wt. % of the first abrasive particles, (b) about 15 to about 40 wt. % of the second abrasive particles, and (c) about 20 to about 70 wt. % of the third abrasive particles.
28. The method of claim 20 , wherein the abrasive comprises (a) about 15 to about 25 wt. % of the first abrasive particles, (b) about 1 to about 10 wt. % of the second abrasive particles, and (c) about 70 to about 80 wt. % of the third abrasive particles.
29. The method of claim 20 , wherein the first abrasive particles have a mean particle size of about 1 μm or less.
30. The method of claim 29 , wherein the first abrasive particles have a mean particle size of about 500 nm or less.
31. The method of claim 20 , wherein the second abrasive particles have a mean aggregate particle size of about 200 nm or less.
32. The method of claim 20 , wherein the third abrasive particles have a mean particle size of about 150 nm or less.
33. The method of claim 20 , wherein the polishing composition further comprises an oxidizing agent.
34. The method of claim 33 , wherein the oxidizing agent comprises hydrogen peroxide.
35. The method of claim 20 , wherein the polishing composition further comprises an acid.
36. The method of claim 35 , wherein the acid is an organic acid.
37. The method of claim 36 , wherein the organic acid is selected from the group consisting of oxalic acid, malonic acid, tartaric acid, acetic acid, lactic acid, propionic acid, phthalic acid, benzoic acid, citric acid, succinic acid, salts thereof, and combinations thereof.
38. The method of claim 20 , wherein the polishing composition has a pH of about 1 to about 4.
39. The method of claim 20 , wherein the substrate comprises a nickel-phosphorous layer.