Etching solution for tungsten and GST films

Patent metadata

Field	Value
Publication number	US-11035044-B2
Application number	US-201815872620-A
Country	US
Kind code	B2
Filing date	Jan 16, 2018
Priority date	Jan 23, 2017
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

Described herein is an etching solution suitable for both tungsten-containing metals and GST metals, which comprises: water; at least one phenolic derivative compound having at least two hydroxyl groups; at least one strong base selected from the group consisting of (i) a quaternary base; (ii) an organic amine; and (iii) a metal hydroxide; optionally an ammonium salt of an organic acid; and optionally a water-miscible solvent, wherein the pH of the etching solution is 10 or greater, and wherein the etching solution is substantially free of a peroxide oxidizer and a metal ion-containing oxidizer.

First claim

The invention claimed is:

1. An etching solution suitable for both tungsten-containing metals and GST metals, which comprises:
water;
from about 1.5% to about 5.0% by weight of gallic acid;
from about 1% to about 60% by weight of at least one strong base selected from the group consisting of (i) a quaternary base having the general formula NR 1 R 2 R 3 R 4 OH, wherein R 1 , R 2 , R 3 and R 4 may be the same as or different from one another and are selected from the group consisting of hydrogen, straight-chained or branched C 1 -C 6 alkyl, and substituted or unsubstituted C 6 -C 10 aryl, and (ii) an organic amine having the general formula NR 1 R 2 R 3 , wherein R 1 , R 2 and R 3 may be the same as or different from one another and are selected from the group consisting of hydrogen, straight-chained or branched C 1 -C 6 alkyl, and a straight-chained or branched C 1 -C 6 alcohol; and
from about 0.1% to about 20% by weight of an ammonium salt of an organic acid selected from triammonium citrate, ammonium acetate, ammonium lactate, diammonium citrate, diammonium succinate, or combinations thereof,
wherein the pH of the etching solution is 10 or greater, and wherein the etching solution is free of oxidizer, is free of fluoride, and is free of surfactant.

2. The etching solution of claim 1 wherein the at least one strong base is a tetraalkylammonium hydroxide.

3. The etching solution of claim 1 wherein the quaternary base is selected from the group consisting of tetraethylammonium hydroxide (TEAH), tetramethyammonium hydroxide (TMAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), tributylmethylammonium hydroxide (TBMAH), benzyltrimethylammonium hydroxide (BTMAH), and combinations thereof.

4. The etching solution of claim 1 wherein the at least one strong base is an organic amine.

5. The etching solution of claim 4 wherein the organic amine is at least one selected from the group consisting of aminoethylethanolamine, N-methylaminoethanol, aminoethoxyethanol, dimethylaminoethoxyethanol, diethanolamine, N-methyldiethanolamine, monoethanolamine, triethanolamine, 1-amino-2-propanol, 2-amino-1-butanol, isobutanolamine, triethylenediamine, and combinations thereof.

6. The etching solution of claim 1 wherein the strong base is tetraethylammonium hydroxide.

7. The etching solution of claim 6 wherein said ammonium salt of an organic acid is triammonium citrate.

8. The etching solution of claim 1 wherein the solution is substantially free of bromine-, chlorine- or iodine-containing compounds.

9. The etching solution of claim 1 wherein said ammonium salt of an organic acid is triammonium citrate.

10. The etching solution of claim 1 further comprising a corrosion inhibitor.

11. The etching solution of claim 1 wherein the solution is capable of etching both GST metal and tungsten metal at a rate of about 1 to about 40 Å/min at room temperature.

12. The etching solution of claim 1 wherein the solution comprises:
from about 10% to about 50% by weight of said at least one strong base.

13. The etching solution of claim 1 wherein the gallic acid is present from about 2.0% to about 3.0% by weight.

14. The etching solution of claim 1 wherein the pH of the etching solution is 12 or greater.

15. A method for etching both GST metal and tungsten metal from a microelectronic device comprising at least one of GST metal and tungsten metal during the manufacture of the microelectronic device, the method comprising the steps of:
contacting the microelectronic device with an aqueous etching solution for a time sufficient to at least partially remove the GST metal and the tungsten metal from the device at a rate of from about 1 to about 40 Å/min at room temperature, wherein the aqueous etching solution comprises:
water;
from about 1.5% to about 5.0% by weight of gallic acid;
from about 1% to about 60% by weight of at least one strong base selected from the group consisting of (i) a quaternary base having the general formula NR 1 R 2 R 3 R 4 OH, wherein R 1 , R 2 , R 3 and R 4 may be the same as or different from one another and are selected from the group consisting of hydrogen, straight-chained or branched C 1 -C 6 alkyl, and substituted or unsubstituted C 6 -C 10 aryl, and (ii) an organic amine having the general formula NR 1 R 2 R 3 , wherein R 1 , R 2 and R 3 may be the same as or different from one another and are selected from the group consisting of hydrogen, straight-chained or branched C 1 -C 6 alkyl, and a straight-chained or branched C 1 -C 6 alcohol; and
from about 0.1% to about 20% by weight of an ammonium salt of an organic acid selected from triammonium citrate, ammonium acetate, ammonium lactate, diammonium citrate, diammonium succinate, or combinations thereof,
wherein the pH of the etching solution is 10 or greater, and wherein the etching solution is free of oxidizer, is free of fluoride, and is free of surfactant.

16. The method of claim 15 wherein the at least one strong base is a tetraalkylammonium hydroxide.

17. The method of claim 15 wherein the quaternary base is selected from the group consisting of tetraethylammonium hydroxide (TEAH), tetramethyammonium hydroxide (TMAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), tributylmethylammonium hydroxide (TBMAH), benzyltrimethylammonium hydroxide (BTMAH), and combinations thereof.

18. The method of claim 15 wherein the etching solution further comprises the water-miscible solvent.

19. The method of claim 15 wherein the at least one strong base is an organic amine.

20. The method of claim 19 wherein the organic amine is at least one selected from the group consisting of aminoethylethanolamine, N-methylaminoethanol, aminoethoxyethanol, dimethylaminoethoxyethanol, diethanolamine, N-methyldiethanolamine, monoethanolamine, triethanolamine, 1-amino-2-propanol, 2-amino-1-butanol, isobutanolamine, triethylenediamine, and combinations thereof.

21. The method of claim 15 wherein the strong base is tetraethylammonium hydroxide.

22. The method of claim 21 wherein said ammonium salt of an organic acid is triammonium citrate.

23. The method of claim 15 wherein the etching solution further comprises a corrosion inhibitor.

24. The method of claim 15 wherein the etching solution is substantially free of bromine-, chlorine- or iodine-containing compounds.

25. The method of claim 15 wherein said ammonium salt of an organic acid is triammonium citrate.

Assignees

• Versum Mat Us Llc

Inventors

• Liu Wen Dar
• Sun Laisheng
• Lee Yi-Chia
• Chen Tianniu
• Han-Adebekun Gang Chris

Classifications

• C09K13/02

  containing an alkali metal hydroxide · CPC title

• C23F1/40

  for etching other metallic material · CPC title

• C23F1/38 Primary

  for etching refractory metals · CPC title

• C09K13/00

  Etching, surface-brightening or pickling compositions (for glass C03C15/00, {C03C25/66; for mortars, concrete, artificial or natural stone or ceramics C04B41/5338}; for metallic material C23F, C23G1/00, C25F1/00; {for semi-conductors H10P52/40}) · CPC title

• H01L45/06

  Electricity · mapped topic