Magnetic memories utilizing a magnetic element having an engineered free layer

• US 7,663,848 B1
• Filed: 09/20/2006
• Issued: 02/16/2010
• Est. Priority Date: 07/14/2006
• Status: Active Grant

• Current Assignee: Samsung Semiconductor Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation), Grandis, Inc. (Samsung Electronics Co. Ltd.)
• Inventors: Chen, Eugene Youjun, Huai, Yiming, Diao, Zhitao
• Primary Examiner(s): Cao; Allen T
• Application Number:
  US11/523,872
• Time in Patent Office: 1,245 Days
• Field of Search: 360/324.2, 360/324.12, 360/324.1, 296/031.3, 296/031.4
• US Class Current: 360/324.2
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H01F 10/325 the spacer being noble metal
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3263 the exchange coupling being symmetric, e.g. for dual spin valve, e.g. NiO/Co/Cu/Co/Cu/Co/NiO
• CPC Class Codes: H01F 10/3272 by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A method and system for providing a magnetic memory are described. The method and system include providing a plurality of magnetic storage cells. Each of the magnetic storage cells includes at least one magnetic element. The magnetic element(s) includes a pinned layer, a barrier layer that is a crystalline insulator and has a first crystalline orientation, and a free layer. The free layer includes a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first and second ferromagnetic layer. The barrier layer resides between the pinned and free layers. The first ferromagnetic layer resides between the barrier layer and the intermediate layer and is ferromagnetically coupled with the second ferromagnetic layer. The intermediate layer is configured such that the first ferromagnetic layer has the first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer. The magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element.

Claims

1. A magnetic memory comprising:

a plurality of magnetic storage cells, each of the plurality of magnetic storage cells including at least one magnetic element, the at least one magnetic element including a pinned layer, a barrier layer, and a free layer, the free layer including a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer, the barrier layer being a crystalline insulator having a first crystalline orientation, the barrier layer residing between the pinned layer and the free layer, the first ferromagnetic layer residing between the barrier layer and the intermediate layer, the first ferromagnetic layer being ferromagnetically coupled with the second ferromagnetic layer, the intermediate layer being configured such that the first ferromagnetic layer has the first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer, and wherein the free layer has a total magnetostriction of substantially zero;

wherein the magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element.

2. The magnetic memory of claim 1 wherein the first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the group of Nb, Hf, Ta, and Ti.

3. A magnetic memory comprising:

a plurality of magnetic storage cells, each of the plurality of magnetic storage cells including at least one magnetic element, the at least one magnetic element including a pinned layer, a barrier layer including MgO, and a free layer, the free layer including a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer, the barrier layer residing between the pinned layer and the free layer, the first ferromagnetic layer residing between the barrier layer and the intermediate layer, the first ferromagnetic layer being ferromagnetically coupled with the second ferromagnetic layer, the first ferromagnetic layer including at least one of CoFe, and CoNiFe, the intermediate layer being configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer, and wherein the free layer has a total magnetostriction of substantially zero;

wherein the magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element.

4. The magnetic memory of claim 3 wherein the first ferromagnetic layer includes at least one of CoFe and CoNiFe.

5. The magnetic memory of claim 4 wherein the first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the group of Nb, Hf, Ta, and Ti, and being greater than zero atomic percent and not more than thirty atomic percent.

6. The magnetic memory of claim 5 wherein X is at least five atomic percent.

7. The magnetic memory of claim 5 wherein the barrier layer is composed of crystalline MgO.

8. The magnetic memory of claim 3 wherein the second ferromagnetic layer includes at least one of CoFeY, CoFeNiY, and an alloy containing at least one of Ni, Fe, and Co, with Y being selected from the group of Nb, Hf, Ta, and Ti, and being greater than zero atomic percent and not more than thirty atomic percent.

9. The magnetic memory of claim 5 wherein the intermediate layer includes at least one of Ru, Re, Cu, an oxide of a ferromagnet, Ir, Rh, Hf, Zr, Ta, and Ti.

10. The magnetic memory of claim 3

wherein the at least one magnetic element further includes:

an additional barrier layer; and

an additional pinned layer, the additional barrier layer residing between the free layer and the additional pinned layer.

11. The magnetic memory of claim 10 wherein the additional barrier layer includes at least one of crystalline MgO and aluminum oxide.

12. The magnetic memory of claim 3 wherein the magnetic element further includes:

a conductive spacer layer; and

an additional pinned layer, the conductive spacer layer residing between the free layer and the additional pinned layer.

13. The magnetic memory of claim 12 wherein the conductive spacer layer includes at least one of Cu and Ru.

14. The magnetic memory of claim 3 wherein the free layer has an easy axis in a first direction and wherein the pinned layer has a magnetization axis in a second direction at an angle from the first direction, the angle being greater than zero degrees and less than one hundred eighty degrees.

15. A magnetic memory comprising:

a plurality of magnetic storage cells, each of the plurality of magnetic storage cells including at least one magnetic element, the at least one magnetic element including a pinned layer, a barrier layer including MgO and a free layer, the free layer including a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer, the barrier layer residing between the pinned layer and the free layer, the first ferromagnetic layer residing between the barrier layer and the intermediate layer, the first ferromagnetic layer being ferromagnetically coupled with the second ferromagnetic layer, the first ferromagnetic layer including at least one of CoFe, and CoNiFe, the intermediate layer being configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer;

wherein the magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element;

wherein the first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the croup of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent; and

wherein the first crystalline orientation is (002).

16. A magnetic memory comprising:

a plurality of magnetic storage cells, each of the plurality of magnetic storage cells including at least one magnetic element, the at least one magnetic element including a pinned layer, a barrier layer including MgO, and a free layer, the free layer including a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer, the barrier layer residing between the pinned layer and the free layer, the first ferromagnetic layer residing between the barrier layer and the intermediate layer, the first ferromagnetic layer being ferromagnetically coupled with the second ferromagnetic layer, the first ferromagnetic layer including at least one of CoFe, and CoNiFe, the intermediate layer being configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer;

wherein the magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element

wherein the free layer further includes an additional intermediate layer and a third ferromagnetic layer, the additional intermediate layer residing between the third ferromagnetic layer and the second ferromagnetic layer the third ferromagnetic layer including at least one of CoFeY and CoNiFeY, with Y being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent, and wherein the magnetic element further includes

an additional barrier layer, the third ferromagnetic layer residing between the additional intermediate layer and the additional barrier layer; and

an additional pinned layer, the additional barrier layer residing between the third ferromagnetic layer and the additional pinned layer.

17. The magnetic memory of claim 16 wherein the additional barrier layer includes at least one of crystalline MgO and aluminum oxide.

18. The magnetic memory of claim 17 wherein the second ferromagnetic layer includes at least one of Ni, Fe, and Co.

19. A magnetic memory comprising:

a plurality of magnetic storage cells, each of the magnetic storage cells including at least one magnetic element, each of the at least one magnetic element including a pinned layer, a barrier layer including crystalline MgO, and a free layer including a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer, the barrier layer residing between the pinned layer and the free layer, the first ferromagnetic layer residing between the barrier layer and the intermediate layer, the first ferromagnetic layer being ferromagnetically coupled with the second ferromagnetic layer, the first ferromagnetic layer including at least one of CoFeX and CoFeNiX with X being selected from the group of Nb, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent, the second ferromagnetic layer including at least one of CoFeY, CoFeNiY, and an alloy containing at least one of Ni, Fe, and Co, with Y being selected from the group of Nb, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent, the intermediate layer being configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer, the intermediate layer including Ru and having a thickness of at least one Angstrom and not more than five Angstroms, the free layer having an easy axis in a first direction and the pinned layer having a magnetization axis in a second direction at an angle from the first direction, the angle being greater than zero degrees and less than one hundred eighty degrees;

wherein the magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element.

20. The magnetic memory of claim 19 wherein the at least one magnetic element further includes:

a conductive spacer layer; and

an additional pinned layer, the conductive spacer layer residing between the free layer and the additional pinned layer.

21. The magnetic memory of claim 19 wherein the at least one magnetic element further includes:

an additional barrier layer; and

an additional pinned layer, the additional barrier layer residing between the free layer and the additional pinned layer.

23. The magnetic memory of claim 19 wherein the free layer has an easy axis in a first direction and wherein the pinned layer has a magnetization axis in a second direction at an angle from the first direction, the angle being greater than zero degrees and less than one hundred eighty degrees.

24. The magnetic memory of claim 19 wherein the intermediate layer includes at least one of Ru, Re, Cu, an oxide of a ferromagnet, Ir, Rh, Hf, Zr, Ta, and Ti.

22. A magnetic memory comprising:

a plurality of magnetic storage cells, each of the magnetic storage cells including at least one magnetic element, each of the at least one magnetic element including a pinned layer, a barrier layer including crystalline MgO, and a free layer including a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer, the barrier layer residing between the pinned layer and the free layer, the first ferromagnetic layer residing between the barrier layer and the intermediate layer, the first ferromagnetic layer being ferromagnetically coupled with the second ferromagnetic layer, the first ferromagnetic layer including at least one of CoFeX and CoFeNiX with X being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent, the second ferromagnetic layer including at least one of CoFeY, CoFeNiY, and an alloy containing at least one of Ni, Fe, and Co, with Y being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent, the intermediate layer being configured such that the first ferromagnetic layer has a first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer, the intermediate layer including Ru and having a thickness of at least one Angstrom and not more than five Angstroms, the free layer having an easy axis in a first direction and the pinned layer having a magnetization axis in a second direction at an angle from the first direction, the angle being greater than zero decrees and less than one hundred eighty decrees;

wherein the magnetic element is configured to allow the free layer to be switched utilizing spin transfer when a write current is passed through the magnetic element; and

wherein the free layer further includes an additional intermediate layer and a third ferromagnetic layer, the additional intermediate layer residing between the third ferromagnetic layer and the second ferromagnetic layer the third ferromagnetic layer including at least one of CoFeZ and CoNiFeZ, with Z being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent, and wherein the magnetic element further includes;

an additional barrier layer, the third ferromagnetic layer residing between the additional intermediate layer and the additional barrier layer; and

an additional pinned layer, the additional barrier layer residing between the third ferromagnetic layer and the additional pinned layer.