Dual additive composition for polishing memory hard disks exhibiting edge roll off

1. A chemical-mechanical polishing composition comprising:

(a) an abrasive comprising colloidal silica,

(b) about 0.001 wt. % to about 1 wt. % of a compound of formula (I):

wherein R is

CH 2 ═CHCONHC(CH 3 ) 2 CH 2 —,

wherein X is independently O or a covalent bond,

or an alkali metal salt thereof,

(c) a compound of formula (II):

wherein R 9 is H or a hydroxyalkyl, and

wherein m is an integer of from 2 to about 6,

(d) hydrogen peroxide, and

(e) water,

wherein the polishing composition has a pH of about 1 to about 5.

2. The polishing composition of claim 1 , wherein the colloidal silica has an average particle size of about 10 nm to about 200 nm.

3. The polishing composition of claim 1 , wherein the abrasive further comprises fused silica.

4. The polishing composition of claim 3 , wherein the fused silica has an average particle size of about 100 nm to about 800 nm.

5. The polishing composition of claim 1 , wherein the compound of formula (I) is 2 acrylamido-2-methyl-1-propanesulfonic acid.

6. The polishing composition of claim 1 , wherein the compound of formula (II) is selected from ethylenediamine, 1,3-diaminopropane, and combinations thereof.

7. The polishing composition of claim 1 , wherein the polishing composition comprises about 0.001 wt. % to about 1 wt. % of the compound of formula (II).

8. The polishing composition of claim 1 , wherein the polishing composition comprises about 0.1 wt. % to about 10 wt. % of a combination of colloidal silica and fused silica.

9. A method of chemically mechanically polishing a substrate comprising:

(i) providing a substrate,

(ii) providing a polishing pad,

(iii) providing a chemical-mechanical polishing composition comprising:

(a) an abrasive comprising colloidal silica,

(b) about 0.001 wt. % to about 1 wt. % of a compound of formula (I):

wherein R is

CH 2 ═CHCONHC(CH 3 ) 2 CH 2 —,

wherein X is independently O or a covalent bond,

or an alkali metal salt thereof,

(c) a compound of formula (II):

wherein R 9 is H or a hydroxyalkyl, and

wherein m is an integer of from 2 to about 6,

(d) hydrogen peroxide, and

(e) water,

wherein the polishing composition has a pH of about 1 to about 5,

(iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition, and

(v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of a surface of the substrate to thereby polish the substrate.

10. The method of claim 9 , wherein the colloidal silica has an average particle size of about 10 nm to about 200 nm.

11. The method of claim 9 , wherein the abrasive further comprises fused silica.

12. The method of claim 11 , wherein the fused silica has an average particle size of about 100 nm to about 800 nm.

13. The method of claim 9 , wherein the compound of formula (1) is 2 acrylamido-2-methyl-1-propanesulfonic acid.

14. The method of claim 9 , wherein the compound of formula (II) is selected from ethylenediamine, 1,3-diaminopropane, and combinations thereof.

15. The method of claim 9 , wherein the polishing composition comprises about 100 ppm to about 500 ppm of the compound of formula (I).

16. The method of claim 9 , wherein the polishing composition comprises about 100 ppm to about 2000 ppm of the compound of formula (II).

17. The method of claim 9 , wherein the polishing composition comprises about 0.1 wt. % to about 10 wt % of a combination of colloidal silica and fused silica.

18. The method of claim 9 , wherein the substrate is a nickel-phosphorous-coated aluminum memory disk, wherein the substrate comprises nickel-phosphorous on a surface of the substrate, and wherein at least a portion of the nickel-phosphorous on a surface of the substrate is abraded to polish the substrate.