Magnetic element utilizing spin-transfer and half-metals and an MRAM device using the magnetic element

• US 7,227,773 B1
• Filed: 10/21/2005
• Issued: 06/05/2007
• Est. Priority Date: 10/09/2002
• Status: Expired due to Term

• Current Assignee: Samsung Semiconductor Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Grandis, Inc. (Samsung Electronics Co. Ltd.)
• Inventors: Nguyen, Paul P., Huai, Yiming
• Primary Examiner(s): Dinh; Son T.
• Application Number:
  US11/256,387
• Time in Patent Office: 592 Days
• Field of Search: 365/158, 365/171, 365/173, 257/295
• US Class Current: 365/158
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A magnetic element that can be used in a memory array having high density includes a pinned layer, a half-metallic material layer, a spacer (or a barrier) layer and a free layer. The half-metallic material layer is formed on the pinned layer and preferably has a thickness that is less than about 100 Å. The half-metallic material layer can be formed to be a continuous layer or a discontinuous on the pinned layer. The spacer (or barrier) layer is formed on the half-metallic material layer, such that the spacer (or barrier) layer is nonmagnetic and conductive (or insulating). The free layer is formed on the spacer (or barrier) layer and has a second magnetization that changes direction based on the spin-transfer effect when a write current passes through the magnetic element.

Claims

1. A magnetic memory device, comprising:

a plurality of magnetic cells including a plurality of magnetic elements, at least one magnetic element including,

a pinned layer and having a first magnetization that is pinned in a first direction,

a half-metallic material layer formed on the pinned layer,

a spacer layer formed on the half-metallic material layer, the spacer layer being nonmagnetic and conductive, and

a free layer formed on the spacer layer, the free layer having a second magnetization that changes direction based on the spin-transfer effect when a write current passes through the magnetic element;

a plurality of rows lines coupled to the plurality of magnetic cells; and

a plurality of column lines coupled to the plurality of magnetic cells, the plurality of row lines and the plurality of column lines selecting a portion of the plurality of magnetic cells for reading and writing;

wherein at least one magnetic element further includes;

a second spacer layer formed on the free layer, the second spacer layer being nonmagnetic and conductive;

a second half-metallic material layer formed on the second spacer layer; and

a second pinned layer formed on the second half-metallic layer, the second pinned layer having a third magnetization that is pinned in a direction that is different from the first direction,

wherein at least one second pinned layer of at least one magnetic element is formed from one of a ferromagnetic material and a ferrimagnetic material.

2. A magnetic memory device, comprising:

a plurality of magnetic cells including a plurality of magnetic elements, at least one magnetic element including,

a pinned layer and having a first magnetization that is pinned in a first direction,

a half-metallic material layer formed on the pinned layer,

a barrier layer formed on the half-metallic material layer, the barrier layer being an insulator and having a thickness that allows tunneling through the barrier layer, and

a free layer formed on the barrier layer, the free layer having a second magnetization that changes direction based on the spin-transfer effect when a write current passes through the magnetic element;

a plurality of rows lines coupled to the plurality of magnetic cells; and

a plurality of column lines coupled to the plurality of magnetic cells, the plurality of row lines and the plurality of column lines selecting a portion of the plurality of magnetic cells for reading and writing.

3. The magnetic memory device according to claim 2, wherein at least one pinned layer of at least one magnetic element is formed from one of a ferromagnetic material and a ferrimagnetic material.

4. The magnetic memory device according to claim 2, wherein at least one pinned layer of at least one magnetic element is formed from a half-metallic material;

wherein the pinned layer and the half-metallic layer form a single layer; and

wherein and the free layer is configured such that the second magnetization changes direction based on the spin-transfer effect when a write current passes through the magnetic element.

5. The magnetic memory device according to claim 2, wherein at least one half-metallic material layer forming at least one pinned layer of at least one magnetic element is one of Fe₃O₄, CrO₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

6. The magnetic memory device according to claim 2, wherein at least one half-metallic material layer of at least one magnetic element is formed from one of Fe₃O₄, Cro₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

7. The magnetic memory device according to claim 2, wherein at least one half-metallic material layer of at least one magnetic element has a thickness that is less than about 100 Å

.

8. The magnetic memory device according to claim 2, wherein at least one half-metallic material layer of at least one magnetic element is a continuous layer.

9. The magnetic memory device according to claim 2, wherein at least one half-metallic material layer of at least one magnetic element is a discontinuous layer.

10. The magnetic memory device according to claim 2, wherein at least one free layer of at least one magnetic element is formed from one of a ferromagnetic material and a ferrimagnetic material.

11. The magnetic memory device according to claim 10, wherein at least one free layer of at least one magnetic element is formed from a half-metallic material.

12. The magnetic memory device according to claim 2, wherein at least one half-metallic material layer of at least one magnetic element is formed from one of Fe₃O₄, CrO₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

13. The magnetic memory device according to claim 2, wherein at least one magnetic element further includes:

a second barrier layer formed on the free layer, the second barrier layer being an insulator and having a thickness that allows tunneling through the second barrier layer;

a second half-metallic material layer formed on the second barrier layer; and

a second pinned layer formed on the second half-metallic layer, the second pinned layer having a third magnetization that is pinned in a direction that is different from the first direction.

14. The magnetic memory device according to claim 13, wherein the second pinned layer is formed from one of a ferromagnetic material and a ferrimagnetic material.

15. The magnetic memory device according to claim 13, wherein the second pinned layer is formed from a half-metallic material, and

wherein the second pinned layer and the second half-metallic layer form a single layer.

16. The magnetic memory device according to claim 15, wherein the half-metallic material layer forming the second pinned layer is one of Fe₃O₄, CrO₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

17. The magnetic memory device according to claim 13, wherein at least one half-metallic material layer of at least one magnetic element is formed from one of Fe₃O₄, CrO₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

18. The magnetic memory device according to claim 13, wherein at least one half-metallic material layer of at least one magnetic element has a thickness that is less than about 100 Å

.

19. The magnetic memory device according to claim 13, wherein at least one half-metallic material layer of at least one magnetic element is formed as a continuous layer.

20. The magnetic memory device according to claim 19, wherein at least one half-metallic material layer of at least one magnetic element is formed as a discontinuous layer.

21. The magnetic memory device according to claim 2, wherein the at least one magnetic element further includes:

a spacer layer formed on the free layer, the spacer layer being nonmagnetic and conductive;

a second half-metallic material layer formed on the spacer layer; and

a second pinned layer formed on the second half-metallic layer, the second pinned layer having a third magnetization that is pinned in a direction that is different from the first direction.

22. The magnetic memory device according to claim 21, wherein the second pinned layer is formed from one of a ferromagnetic material and a ferrimagnetic material.

23. The magnetic memory device according to claim 21, wherein the second pinned layer is formed from a half-metallic material, and

wherein the second pinned layer and the second half-metallic layer form a single layer.

24. The magnetic memory device according to claim 23, wherein the half-metallic material layer forming the second pinned layer is one of Fe₃O₄, CrO₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

25. The magnetic memory device according to claim 21, wherein at least one half-metallic material layer of at least one magnetic element is formed from one of Fe₃O₄, CrO₂, Sr₂FeMoO₆, (La0.7Sr0.3)MnO₃, and NiMnSb.

26. The magnetic memory device according to claim 21, wherein at least one half-metallic material layer of at least one magnetic element has a thickness that is less than about 100 Å

.

27. The magnetic memory device according to claim 21, wherein at least one half-metallic material layer of at least one magnetic element is formed as a continuous layer.

28. The magnetic memory device according to claim 21, wherein at least one half-metallic material layer of at least one magnetic element is formed as a discontinuous layer.

30. The magnetic memory device of claim 2 wherein and the free layer of the at least one magnetic element is configured such that the second magnetization changes direction based on the spin-transfer effect when a write current passes through the at least one magnetic element.

29. A magnetic memory device, comprising:

a plurality of magnetic cells including a plurality of magnetic elements, at least one magnetic element including,

a pinned layer and having a first magnetization that is pinned in a first direction,

a half-metallic material layer formed on the pinned layer,

a barrier layer formed on the half-metallic material layer, the barrier layer being an insulator and having a thickness that allows tunneling through the barrier layer, and

a free layer formed on the barrier layer, the free layer having a second magnetization that changes direction based on the spin-transfer effect when a write current passes through the magnetic element, wherein the free layer has a lateral dimension less than or equal to five hundred nanometer;

a plurality of rows lines coupled to the plurality of magnetic cells, and

a plurality of column lines coupled to the plurality of magnetic cells, the plurality of row lines and the plurality of column lines selecting a portion of the plurality of magnetic cells for reading and writing;

wherein and the free layer of the at least one magnetic element is configured such that the second magnetization changes direction based on the spin-transfer effect when a write current passes through the at least one magnetic element.