Magnetic tunnel junction device

• US 8,969,984 B2
• Filed: 10/08/2013
• Issued: 03/03/2015
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhu, Xiaochun, Kang, Seung Hyuk, Li, Xia, Lee, Kangho
• Primary Examiner(s): POTTER, ROY KARL
• Application Number:
  US14/048,704
• Publication Number:
  US 20140035075A1
• Time in Patent Office: 511 Days
• Field of Search: 257/421, 257/E27.006, 438/3
• US Class Current: 257/421
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A magnetic tunnel junction device includes a Synthetic Anti-Ferromagnetic (SAF) layer, a first free layer, and second free layer. The magnetic tunnel junction device further includes a spacer layer between the first and second free layers. The first free layer is magneto-statically coupled to the second free layer. A thickness of the spacer layer is at least 4 Angstroms.

Claims

1. A magnetic tunnel junction device, comprising:

a semiconductor device comprising;

a Synthetic Anti-Ferromagnetic (SAF) layer;

a first free layer;

a second free layer, and

a spacer layer between the first free layer and the second free layer, wherein the spacer layer is configured to substantially inhibit exchange coupling between the first free layer and the second free layer,

wherein the first free layer is magneto-statically coupled to the second free layer, and

wherein a thickness of the spacer layer is at least 4 Angstroms.

2. The magnetic tunnel junction device of claim 1, wherein the spacer layer comprises a material that substantially inhibits exchange coupling between the first free layer and the second free layer.

3. The magnetic tunnel junction device of claim 1, wherein the spacer layer has a thickness that substantially inhibits exchange coupling between the first free layer and the second free layer.

4. The magnetic tunnel junction device of claim 1, further comprising a spin torque enhancement layer.

5. The magnetic tunnel junction device of claim 4, further comprising a capping layer, adjacent to the spin torque enhancement layer, wherein the capping layer forms a spin barrier but is not a pinning layer.

6. The magnetic tunnel junction device of claim 4, further comprising a spin accumulation layer between the spin torque enhancement layer and the second free layer.

7. The magnetic tunnel junction device of claim 1, further comprising:

an Anti-Ferromagnetic (AFM) pinning layer configured to pin a direction of a magnetic field in the SAF layer.

8. The magnetic tunnel junction device of claim 1, wherein the thickness of the spacer layer is at least 10 Angstroms.

9. The magnetic tunnel junction device of claim 1, wherein a material of the spacer layer comprises one of Ta and MgO.

10. The magnetic tunnel junction device of claim 1, wherein a thickness of the second free layer is greater than a thickness of the first free layer.

11. The magnetic tunnel junction device of claim 1, wherein the magnetic tunnel junction device is in a memory cell and wherein a write current through the magnetic tunnel junction device changes a data value stored in the memory cell.

12. The magnetic tunnel junction device of claim 1, wherein the second free layer is configured to reduce magneto-striction in the first free layer.

13. The magnetic tunnel junction device of claim 1, wherein a first magnetic moment in the first free layer and a second magnetic moment in the second free layer are anti-parallel.

14. The magnetic tunnel junction device of claim 1, wherein a thickness of the first free layer is between 15 and 20 Angstroms and wherein a thickness of the second free layer is between 10 and 60 Angstroms.

15. The magnetic tunnel junction device of claim 1, wherein a thickness of the second free layer is between 15 and 40 Angstroms.

16. The magnetic tunnel junction device of claim 1, wherein the SAF layer comprises a first ferromagnetic layer that is exchange coupled to a second ferromagnetic layer through a second spacer layer.

17. The magnetic tunnel junction device of claim 1, integrated in at least one semiconductor die.

18. The magnetic tunnel junction device of claim 1, further comprising at least one of:

a set top box, a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), a fixed location data unit, or a computer, into which the semiconductor device is integrated.

19. An apparatus, comprising:

means for providing a fixed magnetic field, comprising;

a first ferromagnetic layer;

a second ferromagnetic layer, and

a spacer layer between the first ferromagnetic layer and the second ferromagnetic layer;

a first free layer;

a second free layer, and

means for spacing the first free layer from the second free layer,

wherein the means for spacing includes Ta,

wherein the first free layer is magneto-statically coupled to the second free layer, and

wherein a thickness of the means for spacing is at least 4 Angstroms.

20. The apparatus of claim 19, integrated in at least one semiconductor die.

21. The apparatus of claim 19, further comprising at least one of:

a set top box, a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), a fixed location data unit, or a computer, into which the means for providing a fixed magnetic field, the first free layer, the second free layer, and the means for spacing are integrated.

22. A method of manufacturing a magnetic tunnel junction device, the method comprising:

depositing a Synthetic Anti-Ferromagnetic (SAF) layer;

depositing a first free layer above the SAF layer;

depositing a spacer layer on the first free layer, the spacer layer being configured to substantially inhibit exchange coupling between the first free layer and a second free layer, and

depositing the second free layer on the spacer layer,

wherein the first free layer is configured to be magneto-statically coupled to the second free layer, and

wherein a thickness of the spacer layer is at least 4 Angstroms.

23. The method of claim 22, further comprising depositing an Anti-Ferromagnetic (AFM) pinning layer between a substrate and the SAF layer.

24. The method of claim 22, wherein at least one of the first free layer and the second free layer comprises a ferrous alloy.

25. The method of claim 22, wherein the first free layer, the second free layer, the spacer layer, or a combination thereof, is deposited by a vapor deposition process.

26. The method of claim 22, wherein the spacer layer comprises two layers, and wherein the two layers comprise Ta and MgO, Ta and Mg, or Ta and Ru.

27. The method of claim 22, wherein the spacer layer comprises one of AlCu, AlRu, and AlAg.

28. The method of claim 22, wherein depositing the SAF layer, depositing the first free layer, depositing the spacer layer, and depositing the second free layer are initiated by a processor integrated into an electronic device.

29. A non-transitory computer readable tangible medium storing instructions executable by a computer, the instructions comprising:

instructions that are executable by the computer to control depositing of a Synthetic Anti-Ferromagnetic (SAF) layer;

instructions that are executable by the computer to control depositing of a first free layer above the SAF layer;

instructions that are executable by the computer to control depositing of a spacer layer on the first free layer, the spacer layer being configured to substantially inhibit exchange coupling between the first free layer and a second free layer; and

instructions that are executable by the computer to control depositing of a second free layer on the spacer layer,

wherein the first free layer is configured to be magneto-statically coupled to the second free layer, and

wherein a thickness of the spacer layer is at least 4 Angstroms.

30. The non-transitory computer readable medium of claim 29, further comprising a device selected from a fixed location data unit and a computer, into which the non-transitory computer readable medium is integrated.