Selective deposition and co-deposition processes for ferromagnetic thin films

Patent metadata

Field	Value
Publication number	US-9476124-B2
Application number	US-201514589487-A
Country	US
Kind code	B2
Filing date	Jan 5, 2015
Priority date	Jan 5, 2015
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

A method for selectively depositing a ferromagnetic layer on a conducting layer, includes providing a substrate including a conducting layer; preparing a solution including a metal salt; adding a complexing agent to the solution; adding a reducing agent to the solution; while a temperature of the solution is less than 75° C., immersing the substrate in the solution for a predetermined period to deposit a ferromagnetic layer on the conducting layer by electroless deposition, wherein the ferromagnetic layer comprises one of cobalt (Co), iron (Fe) or CoFe; and after the predetermined period, removing the substrate from the solution.

First claim

What is claimed is:

1. A method for selectively depositing a ferromagnetic layer on a conducting layer, comprising:
providing a substrate including a conducting layer;
preparing a solution including a metal salt;
adding a complexing agent to the solution;
adding a reducing agent to the solution, wherein the reducing agent comprises titanium trichloride and does not include any one of hypophosphite, borohydride, and dimethylamine borane;
while a temperature of the solution is less than 50° C., immersing the substrate in the solution for a predetermined period to deposit a ferromagnetic layer on the conducting layer by electroless deposition, wherein the ferromagnetic layer comprises one of cobalt (Co), iron (Fe) or CoFe; and
after the predetermined period, removing the substrate from the solution.

2. The method of claim 1 , wherein the conducting layer comprises one of copper, ruthenium and cobalt.

3. The method of claim 1 , wherein the metal salt includes at least one of ammonium iron(II) sulfate, cobalt(II) sulfate, iron(II) sulfate, iron(II) chloride, or cobalt(II) chloride.

4. The method of claim 1 , wherein the metal salt includes at least one of cobalt acetate, cobalt chloride, cobalt nitrate, or cobalt(II) sulfate.

5. The method of claim 1 , wherein the complexing agent comprises at least one of tartaric acid, citric acid, gluconic acid or N-(hydroxyethyl)-ethylenediaminetriacetic acid (HEDTA).

6. The method of claim 1 , further comprising adding a buffer to the solution prior to the immersing.

7. The method of claim 6 , wherein the buffer includes boric acid.

8. The method of claim 1 , further comprising adding a pH balancer to the solution prior to the immersing.

9. The method of claim 8 , wherein the pH balancer includes ammonium hydroxide.

10. The method of claim 1 , wherein the solution includes deionized, oxygen-free water, and wherein the metal salt is added to the deionized oxygen-free water.

11. The method of claim 1 , further comprising adding 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt to the solution prior to the immersing.

12. The method of claim 1 , wherein the substrate forms part of a spin-transfer torque random access memory stack.

13. The method of claim 1 , wherein the immersing is performed at a solution temperature between room temperature and 50° C.

14. A method for selectively depositing a ferromagnetic layer on a conducting layer, comprising:
providing a substrate including a conducting layer, wherein the conducting layer includes at least one of copper, ruthenium and cobalt;
preparing a solution including deionized, oxygen-free water and a metal salt, wherein the metal salt includes at least one of ammonium iron(II) sulfate and cobalt(II) sulfate;
adding a reducing agent including titanium trichloride to the solution, wherein the reducing agent does not include any one of hypophosphite, borohydride, and dimethylamine borane;
immersing the substrate in the solution for a predetermined period to deposit a ferromagnetic layer on the conducting layer by electroless deposition, wherein the ferromagnetic layer comprises one of cobalt (Co), iron (Fe) or CoFe, and wherein a temperature of the solution is less than or equal to 50° C. during the immersing; and
after the predetermined period, removing the substrate from the solution.

15. The method of claim 14 , further comprising adding a complexing agent to the solution before the immersing, wherein the complexing agent comprises at least one of tartaric acid, citric acid, gluconic acid or N-(hydroxyethyl)-ethylenediaminetriacetic acid (HEDTA).

16. The method of claim 14 , further comprising adding a buffer to the solution prior to the immersing, wherein the buffer includes boric acid.

17. The method of claim 14 , further comprising adding a pH balancer to the solution prior to the immersing.

18. The method of claim 14 , further comprising adding 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt to the solution prior to the immersing.

19. The method of claim 14 , wherein the substrate forms part of a spin-transfer torque random access memory stack.

Assignees

• Lam Res Corp

Inventors

• Joi Aniruddha
• Chen Ernest
• Dordi Yezdi

Classifications

• C23C18/166

  with two steps starting with addition of reducing agent followed by metal deposition · CPC title

• C23C18/50

  with alloys based on iron, cobalt or nickel · CPC title

• C23C18/1824

  by chemical pretreatment · CPC title

• C23C18/34

  using reducing agents · CPC title

• C23C18/1646

  Characteristics of the product obtained · CPC title