Polishing compositions containing charged abrasive
View Patent ↗Polishing compositions that can selectively and preferentially polish certain dielectric films over other dielectric films are provided herein. These polishing compositions include either cationic or anionic abrasives based on the target dielectric film to be removed and preserved. The polishing compositions utilize a novel electrostatic charge based design, where based on the charge of the abrasives and their electrostatic interaction (forces of attraction or repulsion) with the charge on the dielectric film, various material removal rates and polishing selectivities can be achieved.
1. A polishing composition, comprising:
a) a cationic abrasive comprising alumina, silica, titania, zirconia, a co-formed product thereof, or a mixture thereof, wherein the cationic abrasive comprises terminal groups of formula (I):
—O m —X—(CH 2 ) n —Y (I),
in which m is an integer from 1 to 3; n is an integer from 1 to 10; X is Al, Si, Ti, or Zr; and Y is a cationic amino or a cationic thiol group;
b) an acid, a base, or a mixture thereof; and
c) water;
wherein the polishing composition has a pH of about 2 to about 7; the polishing composition is free of a cationic polymer, and the polishing composition has a zeta potential of from about +0.01 mV to about +100 mV; and
wherein the composition has a first rate of removal of polysilicon, a second rate of removal of silicon nitride, and a ratio of the first rate to the second rate is at least about 10:1.
2. The composition of claim 1 , wherein the composition has a first rate of removal of silicon oxide, a second rate of removal of silicon nitride, and a ratio of the first rate to the second rate is at least about 2:1.
3. The composition of claim 1 , wherein the cationic abrasive is present in the composition in an amount of from about 1 wt% to about 5 wt% based on the total weight of the composition.
4. The composition of claim 1 , wherein the cationic abrasive comprises colloidal alumina, colloidal silica, or colloidal titania.
5. The composition of claim 1 , wherein the cationic abrasive comprises cationic colloidal silica, or base immobilized non-ionic silica.
6. The composition of claim 5 , wherein the silica is prepared by a sol-gel reaction from tetramethyl orthosilicate or tetraethyl orthosilicate.
7. The composition of claim 1 , wherein the cationic abrasive is present in the composition in an amount of from about 0.01 wt % to about 50 wt % based on the total weight of the composition.
8. The composition of claim 1 , wherein the acid is selected from the group consisting of formic acid, acetic acid, malonic acid, citric acid, propionic acid, malic acid, adipic acid, succinic acid, lactic acid, oxalic acid, hydroxyethylidene diphosphonic acid, 2-phosphono-1,2,4-butane tricarboxylic acid, aminotrimethylene phosphonic acid, hexamethylenediamine tetra(methylenephosphonic acid), bis(hexamethylene)triamine phosphonic acid, amino acetic acid, peracetic acid, potassium acetate, phenoxyacetic acid, glycine, bicine, diglycolic acid, glyceric acid, tricine, alanine, histidine, valine, phenylalanine, proline, glutamine, aspartic acid, glutamic acid, arginine, lysine, tyrosine, benzoic acid, nitric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphonic acid, hydrochloric acid, periodic acid, and mixtures thereof.
9. The composition of claim 1 , wherein the base is selected from the group consisting of potassium hydroxide, sodium hydroxide, cesium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, monoethanolamine, tetrabutyl ammonium hydroxide, tetramethylammonium hydroxide, lithium hydroxide, imidazole, triazole, aminotriazole, tetrazole, benzotriazole, tolytriazole, pyrazole, isothiazole, and mixtures thereof.
10. The composition of claim 1 , wherein the acid or base is present in the composition in an amount of from about 0.0001 wt % to about 30 wt % based on the total weight of the composition.
11. The composition of claim 1 , wherein the cationic abrasive has a mean particle size of from about 1 nm to about 5000 nm.
12. The composition of claim 1 , wherein the composition has a zeta potential of from about +5 mV to about +80 mV.
13. The composition of claim 1 , wherein the composition has a conductivity of from about 0.01 mS/cm to about 100 mS/cm.
14. A method, comprising:
applying the polishing composition of claim 1 to a substrate having silicon nitride and at least one of silicon oxide and polysilicon on a surface of the substrate; and
bringing a pad into contact with the substrate and moving the pad in relation to the substrate;
wherein the method removes at least a portion of at least one of silicon oxide and polysilicon at a first rate, the method removes at least a portion of silicon nitride at a second rate, and a ratio of the first rate to the second rate is at least about 2:1.
15. The method of claim 14 , wherein the ratio of the first rate to the second rate is at least about 10:1.
16. The method of claim 14 , wherein the zeta potential difference between the polishing composition and silicon oxide or polysilicon is at least about 20 mV and the zeta potential difference between the polishing composition and silicon nitride is at most about 20 mV.
17. The method of claim 14 , wherein the method removes substantially all of the at least one of silicon oxide and polysilicon on the substrate.
18. The method of claim 17 , further comprises removing at least some of silicon nitride on the substrate.
19. The method of claim 14 , wherein the substrate further comprises an additional material selected from the group consisting of metals, metal oxides, metal nitrides and dielectric materials.
20. The method of claim 14 , further comprising producing a semiconductor device from the substrate treated by the polishing composition.