Methods of removing metal-containing materials
Various methods for selectively etching metal-containing materials (such as, for example, metal nitrides, which can include, for example, titanium nitride) relative to one or more of silicon, silicon dioxide, silicon nitride, and doped silicon oxides in high aspect ratio structures with high etch rates. The etching can utilize hydrogen peroxide in combination with ozone, ammonium hydroxide, tetra-methyl ammonium hydroxide, hydrochloric acid and/or a persulfate. The invention can also utilize ozone in combination with hydrogen peroxide, and/or in combination with one or more of ammonium hydroxide, tetra-methyl ammonium hydroxide and a persulfate. The invention can also utilize ozone, hydrogen peroxide and HCl, with or without persulfate. The invention can also utilize hydrogen peroxide and a phosphate, either alone, or in combination with a persulfate.
1. A method of removing metal-containing material comprising exposing the metal-containing material to a solution comprising H 2 O 2 and a persulfate; wherein the metal-containing material is received between polycrystalline silicon and borophosphosilicate glass, and wherein the solution has a selectivity for removing the metal-containing material relative to the polycrystalline silicon and the borophosphosilicate glass of at least 600:1.
2. The method of claim 1 wherein the persulfate in the solution is provided in the solution as ammonium persulfate.
3. The method of claim 1 wherein the solution further comprises a phosphate.
4. The method of claim 3 wherein the persulfate in the solution is provided in the solution as ammonium persulfate, and wherein the phosphate in the solution is provided as an ammonium phosphate.
5. The method of claim 1 wherein the solution further comprises EDTA.
6. The method of claim 1 wherein the solution further comprises NH 4 OH.
7. The method of claim 1 wherein the solution further comprises tetra-methyl ammonium hydroxide.
8. The method of claim 1 wherein the selectivity for removing the metal-containing material relative to the polycrystalline silicon and the borophosphosilicate glass is at least 10,000:1.
9. The method of claim 1 wherein the metal-containing material comprises a metal nitride.
10. The method of claim 1 wherein the metal-containing material consists essentially of a metal nitride.
11. The method of claim 1 wherein the metal-containing material consists of a metal nitride.
12. The method of claim 1 wherein the metal-containing material comprises titanium nitride.
13. The method of claim 1 wherein the metal-containing material consists essentially of titanium nitride.
14. The method of claim 1 wherein the metal-containing material consists of titanium nitride.
15. The method of claim 1 wherein a temperature of the solution is maintained at from about 65° C. to about 95° C. during the exposing.
16. The method of claim 15 wherein the temperature of the solution is maintained at from about 85° C. to about 95° C. during the exposing.