Method of polishing a tungsten-containing substrate
View Patent ↗The invention provides a method of chemically-mechanically polishing a substrate comprising tungsten through use of a composition comprising a tungsten etchant, an inhibitor of tungsten etching, and water, wherein the inhibitor of tungsten polishing is a polymer, copolymer, or polymer blend comprising at least one repeating group comprising at least one nitrogen-containing heterocyclic ring or a tertiary or quaternary nitrogen atom. The invention further provides a chemical-mechanical polishing composition particularly useful in polishing tungsten-containing substrates.
1. A method of chemically-mechanically polishing a substrate comprising tungstcn, which method comprises:
(i) contacting a substrate with a polishing pad and a chemical-mechanical polishing composition comprising:
(a) a tungsten etchant,
(b) an inhibitor of tungsten etching, wherein the inhibitor of tungsten etching is a polymer, copolymer, or polymer blend comprising at least one repeating group comprising at least one nitrogen-containing heterocyclic ring or a tertiary or quaternary nitrogen atom,
wherein the inhibitor of tungsten etching is present in an amount of about 1 ppm to about 1000 ppm, and
(c) water,
(ii) moving the polishing pad relative to the substrate with the polishing composition therebetween, and
(iii) abrading at least a portion of the substrate to polish the substrate.
2. The method of claim 1 , wherein the tungsten etchant is ferric ion.
3. The method of claim 2 , wherein ferric nitrate is the source of the ferric ion.
4. The method of claim 2 , wherein ferric ion is present in a concentration of about 0.0002 M to about 0.4 M.
5. The method of claim 1 , wherein the inhibitor of tungsten etching is a polyvinylimidazole.
6. The method of claim 5 , wherein the inhibitor of tungsten etching is a poly(1-vinylimidazole).
7. The method of claim 1 , wherein the inhibitor of tungsten etching is a dialkylamine-epichlorohydrin copolymer.
8. The method of claim 1 , wherein the inhibitor of tungsten etching is a copolymer of 2,2′-dichlorodiethyl ether and a bis[Ω-(N,N-dialkyl)alkyl]urea.
9. The method of claim 1 , wherein the polishing composition further comprises a metal oxide abrasive selected from the group consisting of alumina, ceria, silica, titania, zirconia, and mixtures thereof.
10. The method of claim 9 , wherein the metal oxide abrasive is silica.
11. The method of claim 1 , wherein the polishing composition further comprises a per-compound.
12. The method of claim 11 , wherein the per-compound is hydrogen peroxide.
13. The method of claim 12 , wherein hydrogen peroxide is present in the polishing composition in an amount of about 0.1 wt. % to about 10 wt. %.
14. The method of claim 1 , wherein the pH of the polishing composition is about 1 to about 9.
15. The method of claim 14 , wherein the pH of the polishing composition is about 1 to about 6.
16. The method of claim 15 , wherein the pH of the polishing composition is about 1 to about 4.
17. The method of claim 1 , wherein the polishing composition further comprises a stabilizer.
18. The method of claim 17 , wherein the stabilizer comprises an organic acid.
19. The method of claim 18 , wherein the organic acid is selected from the group consisting of malonic acid, citric acid, adipic acid, oxalic acid, and mixtures thereof.
20. The method of claim 1 , wherein the chemical-mechanical polishing composition comprises:
(a) about 0.0002 M to about 0.4 M of ferric nitrate,
(b) about 1 ppm to about 1000 ppm of a polymer selected from the group consisting of polyvinylimidazole, dimethylamine-epichlorohydrin copolymer, and poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea],
(c) hydrogen peroxide,
(d) silica, and
(e) water,
wherein the pH is about 1 to about 6.