Etchant for etching a cobalt-containing member in a semiconductor structure and method of etching a cobalt-containing member in a semiconductor structure

Patent metadata

Field	Value
Publication number	US-11476124-B2
Application number	US-202117141882-A
Country	US
Kind code	B2
Filing date	Jan 5, 2021
Priority date	Jan 5, 2021
Publication date	Oct 18, 2022
Grant date	Oct 18, 2022

Abstract

A method of etching a cobalt-containing member in a semiconductor structure includes providing an etchant including a fluorine-free acid and an alkaline solution having a pH value between 8.5 and 13, and etching the cobalt-containing member in the semiconductor structure using the etchant, wherein a rate of etching the cobalt-containing member by the etchant is substantially greater than a rate of etching a nitride-containing member by the etchant. An etchant for etching a cobalt-containing member in a semiconductor structure includes a fluorine-free acid, and an alkaline solution having a pH value between 8.5 and 13; wherein a rate of etching a cobalt-containing member by the etchant is substantially greater than a rate of etching a nitride-containing member by the etchant, and a level of dissolved oxygen of the etchant is substantially less than or equal to 100 ppb.

First claim

What is claimed is:

1. A method of etching a cobalt-containing member in a semiconductor structure, comprising:
providing an etchant including a fluorine-free acid and an alkaline solution, wherein the alkaline solution has a pH value between 8.5 and 13;
adjusting a level of dissolved oxygen of the etchant to less than or equal to 100 ppb; and
etching the cobalt-containing member in the semiconductor structure using the etchant,
wherein a rate of etching the cobalt-containing member by the etchant is greater than a rate of etching a nitride-containing member by the etchant.

2. The method of claim 1 ,
wherein a pH value of the fluorine-free acid ranges between 2 and 6.

3. The method of claim 1 , wherein the nitride-containing member at least partially surrounds the cobalt-containing member.

4. The method of claim 1 , wherein the fluorine-free acid is selected from a group consisting of: aliphatic monocarboxylic acids wherein the aliphatic group comprises 1 to 18 carbon atoms, aliphatic dicarboxylic acids having an aliphatic group with 1 to 2 carbon atoms, aromatic carboxylic acids, sulfonic acids having 1 to 20 carbon atoms, hydrochloric acid, hydrobromic acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, polyphosphoric acid, nitric acid and perchloric acid.

5. The method of claim 1 , wherein the fluorine-free acid is hydrochloric acid.

6. The method of claim 1 , wherein the alkaline solution includes an alkaline compound, wherein the alkaline compound is selected from a group consisting of: ammonia solution, ethylamine, diethylamine, dimethylethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, choline, pyrrole, piperidine, 1,8-diazabicyclo-[5,4,0]-7-undecene, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and sodium silicate.

7. The method of claim 1 , wherein the alkaline solution includes ammonia solution.

8. The method of claim 1 ,
wherein a pH value of the etchant ranges between 2 and 6.

9. The method of claim 1 , further comprising:
adjusting a concentration of the fluorine-free acid to a value between 0.1 vol % and 10 vol %, and adjusting a concentration of the alkaline solution to a value between 0.1 vol % and 10 vol %.

10. The method of claim 1 , wherein the rate of etching the cobalt-containing member by the etchant is greater than a rate of etching an oxide-containing member by the etchant.

11. The method of claim 1 , wherein the rate of etching a nitride-containing member by the etchant is equal to zero.

12. A method of etching a cobalt-containing member in a semiconductor structure, comprising:
providing the semiconductor structure including a substrate, a plurality of epitaxial structures over the substrate, a gate structure over the substrate and between two of the plurality of epitaxial structures;
disposing the cobalt-containing member over one of the plurality of epitaxial structures and adjacent to the gate structure; and
etching a portion of the conductive material using an etchant,
wherein the etchant includes a fluorine-free acid and an alkaline solution, wherein the alkaline solution has a pH value between 8.5 and 13.

13. The method of claim 12 , wherein the cobalt-containing member is etched to form a surface having a surface roughness between 5 and 15 nm.

14. The method of claim 13 , wherein the surface is free of residues disposed thereon.

15. The method of claim 12 , further comprising:
disposing a nitride-containing material over the substrate and surrounding the gate structure and the cobalt-containing member.

16. The method of claim 15 , wherein the nitride-containing material includes titanium nitride.

17. A method of etching a cobalt-containing member in a semiconductor structure, comprising:
providing the semiconductor structure including the cobalt-containing member disposed over an epitaxial structure and surrounded by a nitride-containing member; and
etching a portion of the cobalt-containing member using an etchant; and
exposing at least a portion of the nitride-containing member after the cobalt-containing member is etched,
wherein the etchant includes a fluorine-free acid and an alkaline solution, wherein the alkaline solution has a pH value between 8.5 and 13.

18. The method of claim 17 , wherein the etchant is free of benzene.

19. The method of claim 17 , wherein the etchant includes hydrochloric acid and ammonia solution.

20. The method of claim 17 , wherein the cobalt-containing members has a width between 10 and 50 nm.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Chen Ren-Kai
• Lee Li-Chen
• Lin Shun Wu
• Yeh Ming-Hsi
• Huang Kuo-Bin

Classifications

• H10W20/4437

  the principal metal being a transition metal · CPC title

• H10P50/667 Primary

  by liquid etching only · CPC title

• H10W20/4403

  based on metals, e.g. alloys, metal silicides (H10W20/4484 takes precedence) · CPC title

• H10W20/40

  Interconnections external to wafers or substrates, e.g. back-end-of-line [BEOL] metallisations or vias connecting to gate electrodes · CPC title

• H10W20/056

  by filling conductive material into holes, grooves or trenches · CPC title