Composition and method for polishing bulk silicon
View Patent ↗The invention provides a polishing composition comprising (a) silica, (b) one or more compounds that increase the removal rate of silicon, (c) one or more tetraalkylammonium salts, and (d) water, wherein the polishing composition has a pH of about 7 to about 11. The invention further provides a method of polishing a substrate with the polishing composition.
1. A method for polishing an edge of a silicon wafer, wherein the edge consists essentially of silicon, which method comprises:
(i) contacting a substrate with a polishing pad and a chemical-mechanical polishing composition consisting essentially of:
(a) about 0.5 wt. % to about 20 wt. % of wet-process silica,
(b) about 0.01 wt. % to about 5 wt. % of an organic carboxylic acid,
(c) about 0.0005 wt. % to about 2 wt. % of an aminophosphonic acid,
(d) about 0.01 wt. % to about 5 wt. % of a tetraalkylammonium salt, wherein the tetraalkylammonium salt comprises a anion selected from the group consisting of hydroxide, chloride, bromide, sulfate, and hydrogensulfate,
(e) potassium hydroxide,
(f) optionally a bicarbonate salt, and
(g) water,
wherein the polishing composition has a pH of about 8 to about 11,
(ii) moving the polishing pad relative to the edge of the silicon wafer with the chemical-mechanical polishing composition therebetween, and
(iii) abrading at least a portion of the edge to polish the edge of the silicon wafer.
2. The method of claim 1 , wherein the organic carboxylic acid is present in the polishing composition in an amount of from about 0.02 wt. % to about 5 wt. %, the aminophosphonic acid is present in the polishing composition in an amount of from about 0.02 wt. % to about 2 wt. %, and the tetraalkylammonium salt is present in the polishing composition in an amount of from about 0.1 wt. % to about 5 wt. %.
3. The method of claim 2 , wherein the wet-process silica is present in the polishing composition in an amount of from about 5 wt. % to about 20 wt. %.
4. The method of claim 3 , wherein the wet-process silica is present in the polishing composition in an amount of from about 10 wt. % to about 15 wt. %.
5. The method of claim 2 , wherein the wet-process silica has an average particle size of about 4 nm to about 180 nm.
6. The method of claim 5 , wherein the wet-process silica has an average particle size of about 20 nm to about 50 nm.
7. The method of claim 2 , wherein the organic carboxylic acid is present in the polishing composition in an amount of from about 0.1 wt. % to about 2 wt. %.
8. The method of claim 7 , wherein the organic carboxylic acid is a hydroxycarboxylic acid.
9. The method of claim 8 , wherein the organic carboxylic acid is selected from the group consisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilic acid, and combinations thereof.
10. The method of claim 2 , wherein the aminophosphonic acid is present in the polishing composition in an amount of from about 0.1 wt. % to about 1 wt. %.
11. The method of claim 10 , wherein the aminophosphonic acid is selected from the group consisting of ethylenediaminetetra(methylene phosphonic acid), amino trimethylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof.
12. The method of claim 11 , wherein the aminophosphonic acid is amino trimethylene phosphonic acid).
13. The method of claim 2 , wherein the polishing composition contains a bicarbonate salt, and the bicarbonate salt is potassium bicarbonate.
14. The method of claim 2 , wherein the polishing composition has a pH of about 8 to about 10.
15. The method of claim 1 , wherein the polishing composition consists essentially of:
(a) about 0.5 wt. % to about 20 wt. % of wet-process silica,
(b) about 0.01 wt. % to about 5 wt. % of an organic carboxylic acid selected from the group consisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilic acid, and combinations thereof,
(c) about 0.0005 wt. % to about 2 wt. % of an aminophosphonic acid selected from the group consisting of ethylenediaminetetra(methylene phosphonic acid), amino trimethylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof,
(d) about 0.01 wt. % to about 5 wt. % of a tetraalkylammonium hydroxide,
(e) about 0.05 wt. % to about 2 wt. % of potassium hydroxide,
(f) about 0.05 wt. % to about 5 wt. % of potassium bicarbonate, and
(g) water.
16. A method for polishing an edge of a wafer, wherein the edge has a surface consisting essentially of silicon and silicon oxide, which method comprises:
(i) contacting a substrate with a polishing pad and a chemical-mechanical polishing composition consisting essentially of:
(a) about 0.5 wt. % to about 20 wt % of silica,
(b) about 0.01 wt. % to about 5 wt. % of an organic carboxylic acid,
(c) about 0.0005 wt. % to about 1 wt. % of an aminophosphonic acid,
(d) about 0.01 wt. % to about 5 wt. % of a tetraalkylammonium salt,
(e) optionally a bicarbonate salt,
(f) optionally potassium hydroxide, and
(g) water,
wherein the polishing composition has a pH of about 7 to about 11,
(ii) moving the polishing pad relative to the edge of the wafer with the chemical-mechanical polishing composition therebetween, and
(iii) abrading at least a portion of the edge to polish the edge of the wafer.
17. The method of claim 16 , wherein the organic carboxylic acid is present in the polishing composition in an amount of from about 0.02 wt. % to about 5 wt. %, the aminophosphonic acid is present in the polishing composition in an amount of from about 0.02 wt. % to about 2 wt. %, and the tetraalkylammonium salt is present in the polishing composition in an amount of from about 0.1 wt. % to about 5 wt. %.
18. The method of claim 17 , wherein the silica is fumed silica.
19. The method of claim 17 , wherein the silica is present in the polishing composition in an amount of from about 5 wt. % to about 20 wt. %.
20. The method of claim 19 , wherein the silica is present in the polishing composition in an amount of from about 10 wt % to about 15 wt. %.
21. The method of claim 17 , wherein the silica has an average particle size of about 4 nm to about 180 nm.
22. The method of claim 21 , wherein the silica has an average particle size of about 20 nm to about 50 nm.
23. The method of claim 17 , wherein the organic carboxylic acid is present in the polishing composition in an amount of from about 0.1 wt. % to about 2 wt. %.
24. The method of claim 23 , wherein the organic carboxylic acid is a hydroxycarboxylic acid.
25. The method of claim 24 , wherein the organic carboxylic acid is selected from the group consisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilic acid, and combinations thereof.
26. The method of claim 17 , wherein the aminophosphonic acid is present in the polishing composition in an amount of from about 0.1 wt. % to about 1 wt. %.
27. The method of claim 26 , wherein the aminophosphonic acid is selected from the group consisting of ethylenediaminetetra(methylene phosphonic acid), amino tri(methylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof.
28. The method of claim 27 , wherein the aminophosphonic acid is amino tri(methylene phosphonic acid).
29. The method of claim 17 , wherein the polishing composition contains a bicarbonate salt, and the bicarbonate salt is potassium bicarbonate.
30. The method of claim 17 , wherein the polishing composition contains potassium hydroxide.
31. The method of claim 17 , wherein the polishing composition has a pH of about 8 to about 10.
32. The method of claim 16 , wherein the polishing composition consists essentially of:
(a) about 0.5 wt. % to about 20 wt. % of wet-process silica,
(b) about 0.01 wt. % to about 5 wt. % of an organic carboxylic acid selected from the group consisting of lactic acid, oxalic acid, 2-hydroxybutyric acid, benzilic acid, and combinations thereof,
(c) about 0.0005 wt. % to about 2 wt. % of an aminophosphonic acid selected from the group consisting of ethylenediaminetetra(methylene phosphonic acid), amino trimethylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof,
(d) about 0.01 wt. % to about 5 wt. % of a tetraalkylammonium hydroxide,
(e) about 0.05 wt. % to about 2 wt. % of potassium hydroxide,
(f) about 0.05 wt. % to about 5 wt. % of potassium bicarbonate, and
(g) water.