Onium-containing CMP compositions and methods of use thereof

1. A chemical-mechanical polishing (CMP) composition consisting essentially of:

(a) colloidal silica;

(b) at least one onium compound selected from the group consisting of a phosphonium salt, a sulfonium salt, and a combination thereof, wherein the phosphomium salt is selected from the group consisting of tetraphenylphosphonium bromide, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, hexyltriphenylphosphonium bromide, benzyltriphenylphosphonium bromide, tetrabutylphosphonium bromide, tetraphenylphosphonium chloride, and tetrabutylphosphonium hydroxide; and the sulfonium salt is selected from a group consisting of trimethylsulfonium bromide, methyldiphenylsulfonium bromide, triphenylsulfonium bromide, dibutyl-2,3-dihydroxypropylsulfonium lactate, and bis-(2-hydroxyethyl)-2,3-dihydroxypropylsulfonium lactate;

(c) an aqueous carrier therefore; the composition having a pH of about 5 or less; wherein the colloidal silica is present in the composition in an amount in the range of about 0.05 to about 35 percent by weight and at least one onium salt is present in the composition in an amount in the range of about 0.04 to about 200 micromoles per gram of composition.

2. The CMP composition of claim 1 wherein the pH is in the range of about 2 to about 5.

3. A chemical-mechanical polishing (CMP) composition comprising:

(a) about 0.1 to about 10 percent by weight of colloidal silica;

(b) about 0.4 to about 20 micromoles per gram of at least one phosphonium salt, wherein the at least one phosphonium salt is selected from the group consisting of tetraphenylphosphonium bromide, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, hexyltriphenylphosphonium bromide, benzyltriphenylphosphonium bromide, tetrabutylphosphonium bromide, tetraphenylphosphonium chloride, and tetrabutylphosphonium hydroxide;

(c) an aqueous carrier therefor;

the composition having a pH of about 5 or less.

4. The CMP composition of claim 3 wherein the colloidal silica is present in the composition in an amount in the range of about 1 to about 6 percent by weight.

5. The CMP composition of claim 3 wherein at least one phosphonium salt is present in the composition in an amount in the range of about 1 to about 10 micromoles per gram of composition.

6. The CMP composition of claim 3 wherein the pH is in the range of about 2 to about 5.

7. A chemical-mechanical polishing (CMP) method for polishing a substrate, the method comprising abrading a surface of the substrate with a CMP composition of claim 1 .

8. The CMP method of claim 7 wherein the at least one onium compound comprises at least one phosphonium salt.

9. A chemical-mechanical polishing (CMP) method for polishing a substrate, the method comprising abrading a surface of the substrate with a CMP composition of claim 3 .

10. A chemical-mechanical polishing (CMP) method for polishing a semiconductor substrate, the method comprising the steps of:

(a) contacting a surface of a semiconductor substrate with a polishing pad and an aqueous CMP composition according to claim 1 ; and

(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the semiconductor surface.

11. The CMP method of claim 10 wherein the colloidal silica is present in the composition in an amount in the range of about 0.05 to about 35 percent by weight.

12. The CMP method of claim 10 wherein at least one phosphonium salt is present in the composition in an amount in the range of about 0.04 to about 200 micromoles per gram of composition.

13. The CMP method of claim 10 wherein the pH of the CMP composition is in the range of about 2 to about 5.

14. The CMP method of claim 10 wherein the substrate comprises silicon dioxide.