Magnetic tunnel junction (MTJ) with a magnesium oxide tunnel barrier

Patent metadata

Field	Value
Publication number	US-9287494-B1
Application number	US-201313954766-A
Country	US
Kind code	B1
Filing date	Jul 30, 2013
Priority date	Jun 28, 2013
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A method for fabricating a magnetic tunnel junction (MTJ) is disclosed. The process involves annealing a stack that includes a tunnel barrier layer and cooling the stack under vacuum immediately after annealing. At least one overlayer is deposited on the tunnel barrier layer to form the MTJ.

First claim

What is claimed is:

1. A method for fabricating a magnetic tunnel junction (MTJ) comprising:
forming a stack that includes a tunnel barrier layer;
annealing the stack immediately after the tunnel barrier layer is deposited;
cooling the stack under vacuum; and
then depositing at least one overlayer on the tunnel barrier layer to form the MTJ after the step of cooling the stack under vacuum.

2. The method of claim 1 , further comprising depositing a free layer on the tunnel barrier followed by a capping layer on the free layer.

3. The method of claim 1 , wherein the tunnel barrier layer has an approximate thickness of between four and seven angstroms.

4. The method of claim 1 , wherein the stack is annealed at a temperature between 155° C. and 200° C.

5. The method of claim 1 , wherein annealing occurs in the absence of a magnetic field in a pre-heated chamber.

6. The method of claim 1 , wherein the stack is cooled for approximately 5-35 minutes in a holding chamber that is maintained at room temperature.

7. The method of claim 1 , wherein the MTJ has an MR ratio that increases as the cooling period increases.

8. The product formed by the process of claim 1 .

9. A method for fabricating a magnetic tunnel junction (MTJ) comprising:
providing a stack of layers;
depositing a tunnel barrier layer on the stack of layers to form an intermediate structure;
annealing the intermediate structure after the tunnel barrier layer is deposited and in the absence of a magnetic field; and
cooling the tunnel barrier layer under vacuum prior to depositing at least one overlayer to form the MTJ.

10. The method of claim 9 , further comprising providing a free layer on the tunnel barrier layer, and a capping layer on the free layer.

11. The method of claim 9 , wherein the tunnel barrier layer has an approximate thickness of between four and seven angstroms.

12. The method of claim 9 , wherein the intermediate structure is annealed at a temperature between 155° C. to 200° C. prior to deposition of the at least one overlayer.

13. The method of claim 9 , wherein annealing occurs in a pre-heated chamber.

14. The method of claim 9 , wherein the intermediate structure is placed in a holding chamber for a period of 5-35 minutes to cool to a temperature between 24° C.-190° C.

15. The method of claim 14 , wherein the holding chamber is maintained at a temperature of between 24° C.-30° C.

16. The method of claim 9 , wherein the MTJ has an MR ratio that increases as the cooling period increases.

17. The method of claim 9 , wherein the MTJ has an MR ratio between 60% and 90% at resistance-area product values between 0.55 and 0.85 Ωμm 2 .

18. A method for fabricating a magnetic tunnel junction (MTJ) comprising:
forming a stack of layers;
depositing a tunnel barrier layer on the stack of layers to form an intermediate structure
annealing the intermediate structure after the tunnel barrier layer is deposited; and
cooling the tunnel barrier layer under vacuum prior to depositing at least one overlayer to form an MTJ, wherein the MTJ has an MR ration between 60% and 90% at resistance-area product values between 0.55 and 085 Ωμm 2 .

Assignees

• Western Digital Fremont Llc

Inventors

• Yan Minglang
• Huang Xiaobo
• Shen Jian X

Classifications

• G01R33/09

  Magnetoresistive devices · CPC title

• H01L27/222

  Electricity · mapped topic

• H01L43/00

  Electricity · mapped topic

• H01L27/22

  Electricity · mapped topic

• H01L43/12 Primary

  Electricity · mapped topic