Magnetostatically coupled magnetic elements utilizing spin transfer and an MRAM device using the magnetic element

• US 6,847,547 B2
• Filed: 02/28/2003
• Issued: 01/25/2005
• Est. Priority Date: 02/28/2003
• 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, Albert, Frank
• Primary Examiner(s): PHUNG, ANH K
• Application Number:
  US10/377,689
• Publication Number:
  US 20040170055A1
• Time in Patent Office: 697 Days
• Field of Search: 365/173, 365/171, 365/158
• US Class Current: 365/173
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect

Abstract

A method and system for providing a magnetic element and a corresponding memory are disclosed. In one aspect, the method and system include providing a dual spin tunnel/valve structure and at least one spin valve. The dual spin tunnel/valve structure includes a nonmagnetic spacer layer between a pinned layer and a free layer, another pinned layer and a barrier layer between the free layer and the other pinned layer. The free layers of the dual spin tunnel/valve structure and the spin valve are magnetostatically coupled. In one embodiment a separation layer resides between the dual spin tunnel/valve structure and the spin valve. In another aspect, the method and system include providing two dual spin valves, a spin tunneling junction there between and, in one embodiment, the separation layer. In both aspects, the magnetic element is configured to write to the free layers using spin transfer when a write current is passed through the magnetic element.

Claims

1. A magnetic element comprising:

a spin tunneling structure including a first pinned layer, a barrier layer, a first free layer, a first nonmagnetic spacer layer, and a second pinned layer, the first pinned layer being ferromagnetic and having a first pinned layer magnetization, the first pinned layer magnetization being pinned in a first direction, the barrier layer being an insulator and having a thickness that allows tunneling through the barrier layer, the barrier layer being disposed between the first pinned layer and the first free layer, the first free layer being ferromagnetic and having a first free layer magnetization, the first nonmagnetic spacer layer being conductive and disposed between the second pinned layer and the first free layer, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction;

a spin valve structure having a third pinned layer, a second nonmagnetic spacer layer and a second free layer, the third pinned layer being ferromagnetic and having a third pinned layer magnetization, the third pinned layer magnetization being pinned in a third direction, the second free layer being ferromagnetic and having a second free layer magnetization, the second nonmagnetic spacer layer being conductive and residing between the second free layer and the second pinned layer, the first free layer and the second free layer being disposed such that the first free layer and the second free layer are magnetostatically coupled;

wherein the magnetic element is configured to allow the first and/or second free layer magnetization to change direction due to spin transfer when a write current is passed through the magnetic element.

2. The magnetic element of claim 1 further comprising:

a separation layer residing between the first free layer of the spin tunneling structure and the second free layer of the spin valve, the separation layer being configured to allow the first free layer and the second free layer to be magnetostatically coupled.

3. The magnetic element of claim 2 further comprising:

an antiferromagnetic layer adjacent to the second pinned layer, the antiferromagnetic layer for pinning the second pinned layer magnetization; and

wherein the separation layer resides between and adjacent to the antiferromagnetic layer and the second free layer.

4. The magnetic element of claim 1 wherein the first free layer and the second free layer are magnetostatically coupled such that the first free layer magnetization is antiparallel to the second free layer magnetization.

5. The magnetic element of claim 1 wherein the first pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

6. The magnetic element of claim 1 wherein the third pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

7. The magnetic element of claim 1 wherein the spin valve is a dual spin valve and further includes a fourth pinned layer and a third nonmagnetic spacer layer disposed between the second free layer and the fourth pinned layer, the second free layer residing between the fourth pinned layer and the third pinned layer, the fourth pinned layer being magnetic and having a fourth pinned layer magnetization pinned in a fourth direction.

8. The magnetic element of claim 7 wherein the first pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

9. The magnetic element of claim 7 wherein the fourth pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

10. The magnetic element of claim 7 further comprising:

a second dual spin valve including a fifth pinned layer, a fourth nonmagnetic spacer layer, a third free layer, a fifth nonmagnetic spacer layer, and a sixth pinned layer, the fourth nonmagnetic spacer layer residing between the fifth pinned layer and the third free layer, the third free layer residing between the fifth pinned layer and the sixth pinned layer, the fifth nonmagnetic spacer layer residing between the third free layer and the sixth pinned layer, the fifth pinned layer having a fifth pinned layer magnetization pinned in a fifth direction, the sixth pinned layer having a sixth pinned layer magnetization pinned in a sixth direction, the third free layer having a third free layer magnetization, the first free layer and the third free layer being disposed such that the first free layer and the third free layer are magnetostatically coupled.

11. The magnetic element of claim 10 wherein the first free layer and the third free layer are magnetostatically coupled such that the first free layer magnetization is antiparallel to the third free layer magnetization.

12. A magnetic element comprising:

a spin tunneling junction having a first pinned layer, a barrier layer, and a first free layer, the barrier layer residing between the first pinned layer and the first free layer, the first pinned layer being ferromagnetic and having a first pinned layer magnetization pinned in a first direction, the first free layer being ferromagnetic and having a first free layer magnetization, the barrier layer being an insulator and having a first thickness that allow tunneling through the barrier layer;

a first dual spin valve having a second pinned layer, a first nonmagnetic spacer layer, a second free layer, a second nonmagnetic spacer layer and a third pinned layer, the second pinned layer residing between the second free layer and the first free layer, the first nonmagnetic spacer residing between the second pinned layer and the second free layer, the second free layer residing between the second pinned layer and the third pinned layer, the second nonmagnetic spacer layer residing between the second free layer and the third pinned layer, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction, the third pinned layer being ferromagnetic and having a third pinned layer magnetization pinned in a third direction, the second free layer being ferromagnetic and having a second free layer magnetization, the first free layer and the second free layer being magnetostatically coupled, the first nonmagnetic spacer layer being conductive;

a second dual spin valve having a fourth pinned layer, a third nonmagnetic spacer layer, a third free layer, a fourth nonmagnetic spacer layer and a fifth pinned layer, the fourth pinned layer residing between the first free layer and the third free layer, the third nonmagnetic spacer residing between the fourth pinned layer and the third free layer, the fourth nonmagnetic spacer residing between the third free layer and the fifth pinned layer, the fourth pinned layer being ferromagnetic and having a fourth pinned layer magnetization pinned in a fourth direction, the fifth pinned layer being ferromagnetic and having a fifth pinned layer magnetization pinned in a fifth direction, the third free layer being ferromagnetic and having a third free layer magnetization, the first free layer and the third free layer being magnetostatically coupled;

wherein the magnetic element is configured to allow the second free layer magnetization and the third free layer magnetization to change direction due to spin transfer when a write current is passed through the magnetic element.

13. The magnetic element of claim 12 further comprising:

a separation layer residing between the first free layer of the spin tunneling junction and the second pinned layer of the first dual spin valve, the separation layer being configured to allow the first free layer and the second free layer to be magnetostatically coupled.

14. The magnetic element of claim 13 wherein the first free layer and the second free layer are magnetostatically coupled such that the first free layer magnetization is antiparallel to the second free layer magnetization.

15. The magnetic element of claim 14 wherein the first free layer and the third free layer are magnetostatically coupled such that the first free layer magnetization is antiparallel to the third free layer magnetization.

16. The magnetic element of claim 12 wherein the first pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

17. The magnetic element of claim 12 wherein the third pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

18. The magnetic element of claim 12 wherein the fourth pinned layer is a synthetic pinned layer including a first ferromagnetic layer and a second ferromagnetic layer separated by a nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically coupled.

19. The magnetic element of claim 12 wherein the spin tunneling junction is a dual spin tunneling junction further including a second barrier layer and a sixth pinned layer, the first free layer residing between the first pinned layer and the sixth pinned layer, the second barrier layer residing between the first free layer and the sixth pinned layer, the sixth pinned layer being ferromagnetic and having a sixth pinned layer magnetization pinned in a sixth direction, the barrier layer being an insulator and having a first thickness that allow tunneling through the barrier layer.

20. A magnetic memory device comprising:

a plurality of magnetic cells including a plurality of magnetic elements, each of the plurality of magnetic elements including a spin tunneling structure and a spin valve structure, the spin tunneling structure including a first pinned layer, a barrier layer, a first free layer, a first nonmagnetic spacer layer, and a second pinned layer, the first pinned layer being ferromagnetic and having a first pinned layer magnetization, the first pinned layer magnetization being pinned in a first direction, the barrier layer being an insulator and having a thickness that allows tunneling through the barrier layer, the barrier layer being disposed between the first pinned layer and the first free layer, the first free layer being ferromagnetic and having a first free layer magnetization, the first nonmagnetic spacer layer being conductive and disposed between the second pinned layer and the first free layer, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction, the spin valve structure having a third pinned layer, a second nonmagnetic spacer layer and a second free layer, the third pinned layer being ferromagnetic and having a third pinned layer magnetization, the third pinned layer magnetization being pinned in a third direction, the second free layer being ferromagnetic and having a second free layer magnetization, the second nonmagnetic spacer layer being conductive and residing between the second free layer and the second pinned layer) the first free layer and the second free layer being disposed such that the first free layer and the second free layer are magnetostatically coupled, the magnetic element is configured to allow the first and/or second free layer magnetization to change direction due to spin transfer when a write current is passed through the magnetic element;

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

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

21. The magnetic memory device of claim 20 wherein each of the plurality of magnetic elements further includes a separation layer residing between the first free layer of the spin tunneling structure and the second free layer of the spin valve, the separation layer being configured to allow the first free layer and the second free layer to be magnetostatically coupled.

22. The magnetic memory device of claim 20 wherein the spin valve is a dual spin valve and further includes a fourth pinned layer and a third nonmagnetic spacer layer disposed between the second free layer and the fourth pinned layer, the second free layer being disposed between the third pinned layer and the fourth pinned layer the fourth pinned layer being magnetic and having a fourth pinned layer magnetization pinned in a fourth direction.

23. The magnetic memory device of claim 22 wherein each of the plurality of magnetic elements further includes:

a second dual spin valve including a fifth pinned layer, a fourth nonmagnetic spacer layer, a third free layer, a fifth nonmagnetic spacer layer, and a sixth pinned layer, the fourth nonmagnetic spacer residing between the fifth pinned layer and the third free layer, the third free layer residing between the fifth pinned layer and the sixth pinned layer, the fifth nonmagnetic spacer layer residing between the third free layer and the sixth pinned layer, the fifth pinned layer having a fifth pinned layer magnetization pinned in a fifth direction, the sixth pinned layer having a sixth pinned layer magnetization pinned in a sixth direction, the third free layer having a third free layer magnetization, the first free layer and the third free layer being disposed such that the first free layer and the third free layer are magnetostatically coupled.

24. A magnetic memory device comprising:

a plurality of magnetic cells including a plurality of magnetic elements, each of the plurality of magnetic elements including a spin tunneling junction, a first dual spin valve and a second dual spin valve, the spin tunneling junction having a first pinned layer, a barrier layer, and a first free layer, the barrier layer residing between the first pinned layer and the first free layer, the first pinned layer being ferromagnetic and having a first pinned layer magnetization pinned in a first direction, the first free layer being ferromagnetic and having a first free layer magnetization, the barrier layer being an insulator and having a first thickness that allow tunneling through the barrier layer, the first dual spin valve having a second pinned layer, a first nonmagnetic spacer layer, a second free layer, a second nonmagnetic spacer layer and a third pinned layer, the second pinned layer residing between the second free layer and the first free layer, the first nonmagnetic spacer residing between the second pinned layer and the second free layer, the second free layer residing between the second pinned layer and the third pinned layer, the second nonmagnetic spacer residing between the second free layer and the third pinned layer, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction, the third pinned layer being ferromagnetic and having a third pinned layer magnetization pinned in a third direction, the second free layer being ferromagnetic and having a second free layer magnetization, the first free layer and the second free layer being magnetostatically coupled, the first nonmagnetic spacer layer being conductive, the second dual spin valve having a fourth pinned layer, a third nonmagnetic spacer layer, a third free layer, a fourth nonmagnetic spacer layer and a fifth pinned layer, the fourth pinned layer residing between the first free layer and the third free layer, the third nonmagnetic spacer residing between the fourth pinned layer and the third free layer, the fourth nonmagnetic spacer residing between the third free layer and the fifth pinned layer, the fourth pinned layer being ferromagnetic and having a fourth pinned layer magnetization pinned in a fourth direction, the fifth pinned layer being ferromagnetic and having a fifth pinned layer magnetization pinned in a fifth direction, the third free layer being ferromagnetic and having a third free layer magnetization, the first free layer and the third free layer being magnetostatically coupled, wherein the magnetic element is configured to allow the second free layer magnetization and the third free layer magnetization to change direction due to spin transfer when a write current is passed through the magnetic element;

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

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

25. The magnetic memory device of claim 24 wherein each of the plurality of elements further includes a separation layer residing between the first free layer of the spin tunneling junction and the second pinned layer of the first dual spin valve, the separation layer being configured to allow the first free layer and the second free layer to be magnetostatically coupled.

26. The magnetic element of claim 24 wherein the spin tunneling junction is a dual spin tunneling junction further including a second barrier layer and a sixth pinned layer, the first free layer residing between the first pinned layer and the sixth pinned layer, the second barrier layer residing between the first free layer and the sixth pinned layer, the sixth pinned layer being ferromagnetic and having a sixth pinned layer magnetization pinned in a sixth direction, the barrier layer being an insulator and having a first thickness that allow tunneling through the barrier layer.

27. A method for providing magnetic element comprising the steps of:

(a) providing a spin tunneling structure including a first pinned layer, a barrier layer, a first free layer, a first nonmagnetic spacer layer and a second pinned layer, the first pinned layer being ferromagnetic and having a first pinned layer magnetization, the first pinned layer magnetization being pinned in a first direction, the barrier layer being an insulator and having a thickness that allows tunneling through the barrier layer, the barrier layer being disposed between the first pinned layer and the first free layer, the first free layer being ferromagnetic and having a first free layer magnetization, the first nonmagnetic spacer layer being conductive and disposed between the second pinned layer and the first free layer, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction; and

(b) providing a spin valve structure having a third pinned layer, a second nonmagnetic spacer layer and a second free layer, the third pinned layer being ferromagnetic and having a third pinned layer magnetization, the third pinned layer magnetization being pinned in a third direction, the second free layer being ferromagnetic and having a second free layer magnetization, the second nonmagnetic spacer layer being conductive and residing between the second free layer and the second pinned layer, the first free layer and the second free layer being disposed such that the first free layer and the second free layer are magnetostatically coupled;

wherein the magnetic element is configured to allow the first and/or second free layer magnetization to change direction due to spin transfer when a write current is passed through the magnetic element.

28. A The method of claim 27 further comprising the step of:

(c) providing a separation layer residing between the first free layer of the spin tunneling structure and the second free layer of the spin valve, the separation layer being configured to allow the first free layer and the second free layer to be magnetostatically coupled.

29. The method of claim 27 wherein the spin valve is a dual spin valve and wherein the spin valve providing step (b) further includes the steps of:

(b1) providing a fourth pinned layer; and

(b2) providing a third nonmagnetic spacer layer disposed between the second free layer and the fourth pinned layer, the second free layer being disposed between the third pinned layer and the fourth pinned layer, the fourth pinned layer being magnetic and having a fourth pinned layer magnetization pinned in a fourth direction.

30. The method of claim 29 further comprising:

(c) providing a second dual spin valve including a fifth pinned layer, a fourth nonmagnetic spacer layer, a third free layer, a fifth nonmagnetic spacer layer, and a sixth pinned layer, the fourth nonmagnetic spacer residing between the fifth pinned layer and the third free layer, the third free layer residing between the fifth pinned layer and the sixth pinned layer, the fifth nonmagnetic spacer layer residing between the third free layer and the sixth pinned layer, the fifth pinned layer having a fifth pinned layer magnetization pinned in a fifth direction, the sixth pinned layer having a sixth pinned layer magnetization pinned in a sixth direction, the third free layer having a third free layer magnetization, the first free layer and the third free layer being disposed such that the first free layer and the third free layer are magnetostatically coupled.

31. A method for providing a magnetic element comprising the steps of:

(a) providing a spin tunneling junction having a first pinned layer, a barrier layer, and a first free layer, the barrier layer residing between the first pinned layer and the first free layer, the first pinned layer being ferromagnetic and having a first pinned layer magnetization pinned in a first direction, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction, the first free layer being ferromagnetic and having a first free layer magnetization, the barrier layer being an insulator and having a first thickness that allow tunneling through the barrier layer;

(b) providing a first dual spin valve having a second pinned layer, a first nonmagnetic spacer layer, a second free layer, a second nonmagnetic spacer layer and a third pinned layer, the second pinned layer residing between the second free layer and the first free layer, the first nonmagnetic spacer residing between the second pinned layer and the second free layer, the second free layer residing between the second pinned layer and the third pinned layer, the second nonmagnetic spacer residing between the second free layer and the third pinned layer, the second pinned layer being ferromagnetic and having a second pinned layer magnetization pinned in a second direction, the third pinned layer being ferromagnetic and having a third pinned layer magnetization pinned in a third direction, the second free layer being ferromagnetic and having a second free layer magnetization, the first free layer and the second free layer being magnetostatically coupled, the first nonmagnetic spacer layer being conductive;

(c) providing a second dual spin valve having a fourth pinned layer, a third nonmagnetic spacer layer, a third free layer, a fourth nonmagnetic spacer layer and a fifth pinned layer, the fourth pinned layer residing between the first free layer and the third free layer, the third nonmagnetic spacer residing between the fourth pinned layer and the third free layer, the fourth nonmagnetic spacer residing between the third free layer and the fifth pinned layer, the fourth pinned layer being ferromagnetic and having a fourth pinned layer magnetization pinned in a fourth direction, the fifth pinned layer being ferromagnetic and having a fifth pinned layer magnetization pinned in a fifth direction, the third free layer being ferromagnetic and having a third free layer magnetization, the first free layer and the third free layer being magnetostatically coupled, wherein the magnetic element is configured to allow the second free layer magnetization to change direction due to spin transfer when a write current is passed through the magnetic element.

32. The method of claim 31 further comprising the step of:

(d) providing a separation layer residing between the first free layer of the spin tunneling junction and the second pinned layer of the first dual spin valve, the separation layer being configured to allow the first free layer and the second free layer to be magnetostatically coupled.

33. The method of claim 32 wherein the spin tunneling junction is a dual spin tunneling junction and wherein the spin tunneling junction providing step (a) further includes the step of:

(a1) providing a second barrier layer;

(a2) providing a sixth pinned layer, the second barrier layer residing between the first free layer and the sixth pinned layer, the first free layer residing between the first pinned layer and the sixth pinned layer, the sixth pinned layer being ferromagnetic and having a sixth pinned layer magnetization pinned in a sixth direction, the barrier layer being an insulator and having a first thickness that allow tunneling through the barrier layer.