Solution for the selective removal of metal from aluminum substrates
View Patent ↗The present disclosure relates to a solution for selectively removing metal, such as Ta or TaN, from a substrate, such as an aluminum containing substrate. The solution comprises an acid, such as HF or buffered HF, an ingredient comprising a fluorine ion, such as ammonium fluoride (NH 4 F), ethylene glycol, and water. A method of selectively removing metal from a substrate using this solution is also disclosed.
1. A method comprising:
contacting an aluminum-containing substrate with a solution to selectively remove a metal containing coating from the aluminum-containing substrate, the solution comprising in weight % of the solution:
1-20% of at least one acid selected from the group consisting of hydrofluoric acid (HF), hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and mixtures thereof,
1-10% of at least one ingredient comprising a fluorine ion, wherein the ingredient is selected from the group consisting of ammonium fluoride (NH 4 F), potassium fluoride, sodium fluoride, and mixtures thereof,
50-60% ethylene glycol, and
water,
forming an aluminum ethoxide layer on an exposed portion of the substrate that is not covered by the coating;
wherein said substrate is contacted with the solution for a time sufficient to remove the coating from the substrate with substantially no substrate erosion.
2. The method of claim 1 , wherein the substrate comprises a material selected form the group consisting of elemental aluminum, aluminum nitride, aluminum boride and mixtures thereof.
3. The method of claim 1 , wherein the at least one ingredient comprising a fluorine ion is ammonium fluoride (NH 4 F).
4. The method of claim 1 , wherein said solution further comprises at least one anionic, non ionic, cationic, or amphoteric surfactant.
5. The method of claim 4 , wherein the at least one surfactant is selected from the group consisting of primary amines of chain length C 2 to C 12 , secondary amines of chain length C 2 to C 12 tertiary amines of chain length C 2 to C 12 , amides, fluorocarbons and alkylethoxylates.
6. The method of claim 1 , wherein said solution has a pH of less than 6.
7. The method of claim 1 , wherein the metal containing coating comprises a metal or metal compound selected from the group consisting of copper, tungsten, titanium, tantalum, and oxides, borides, nitrides, carbides, alloys and mixtures thereof.
8. The method of claim 7 , wherein the metal containing coating comprises a material selected from the group consisting of metallic tantalum and tantalum nitride.
9. The method of claim 1 , wherein the at least one acid is HF.
10. The method of claim 9 , wherein the at least one ingredient comprising a fluorine ion is present in amount ranging from 1-5%, by weight, of the solution.
11. The method of claim 1 , wherein the solution is heated to a temperature up to 120° C.
12. The method of claim 11 , wherein the solution is heated to a temperature ranging from 85° C. to 95° C.
13. The method of claim 12 , wherein the solution is heated to a temperature ranging from room temperature up to 85° C.
14. A method for selectively removing metal from a substrate comprising aluminum and being at least partially covered with a metal selected from the group consisting of Ta and TaN, said method comprising:
contacting the substrate with a solution comprising, in % weight of the solution,
1-20% HF, buffered HF or mixtures thereof,
1-15% NH 4 F,
40-95% ethylene glycol, and
the balance of water,
forming an aluminum ethoxide layer on at least one portion of exposed aluminum substrate,
wherein the substrate is contacted with the solution for a time sufficient to remove Ta or TaN from the substrate with substantially no substrate erosion, wherein said solution is heated to a temperature ranging from 85 to 95° F. prior to or during contact with the substrate.
15. The method of claim 14 , wherein the solution comprises 1-10% of the NH 4 F, in wt % of the solution.
16. The method of claim 15 , wherein the solution comprises 50-60% of the ethylene glycol, in wt % of the solution.
17. The method of claim 15 , wherein the solution comprises 1-5% of the NH 4 F, in wt % of the solution.