MRAM DEVICE WITH IMPROVED STACK STRUCTURE AND OFFSET FIELD FOR LOW-POWER TOGGLE MODE WRITING

• US 20060152969A1
• Filed: 01/10/2005
• Published: 07/13/2006
• Est. Priority Date: 01/10/2005
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Trouilloud, Philip L.
• Granted Patent: US 7,622,784 B2
• Time in Patent Office: Days
• US Class Current: 365/171
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect

Abstract

A magnetic random access memory (MRAM) device includes a reference magnetic region having a resultant magnetic moment vector generally maintained in a desired orientation without the use of exchange coupling thereto. A storage magnetic region has an anisotropy easy axis and a resultant magnetic moment vector oriented in a position parallel or antiparallel to that of the reference magnetic region. A tunnel barrier is disposed between the reference magnetic region and the storage magnetic region, with the reference magnetic region, storage magnetic region and tunnel barrier defining a storage cell configured for a toggle mode write operation. The storage cell has an offset field applied thereto so as to generally maintain the resultant magnetic moment vector of the reference magnetic region in the desired orientation.

Claims

1. A magnetic random access memory (MRAM) device, comprising:

a reference magnetic region having a resultant magnetic moment vector generally maintained in a desired orientation without the use of exchange coupling thereto;

a storage magnetic region having an anisotropy easy axis and a resultant magnetic moment vector oriented in a position parallel or antiparallel to that of said reference magnetic region;

a tunnel barrier disposed between said reference magnetic region and said storage magnetic region;

said reference magnetic region, said storage magnetic region and said tunnel barrier defining a storage cell configured for a write operation thereto by a toggle mode; and

said storage cell having an offset field applied thereto so as to generally maintain said resultant magnetic moment vector of said reference magnetic region in said desired orientation.

2. The MRAM device of claim 1, wherein said offset field further alters the magnitude of switching field used to perform said toggle mode write operation of said storage magnetic region.

3. The MRAM device of claim 1, further comprising a bias element configured to generate said offset field, said bias element disposed outside a vertical stack of said storage cell.

4. The MRAM device of claim 3, wherein said bias element is configured within an array of MRAM storage elements, said array of MRAM storage elements including said storage cell.

5. The MRAM device of claim 4, wherein said bias element is configured between said storage cell and an adjacent storage cell within said array.

6. The MRAM device of claim 5, wherein said bias element is oriented at about 45 degrees with respect to a wordline and a bitline axis of said array.

7. The MRAM device of claim 6, wherein said bias element is disposed proximate corresponding tunnel barriers of said storage cell and said adjacent storage cell.

8. The MRAM device of claim 1, wherein said reference magnetic region has a coercivity of less than about 100 Oersteds (Oe).

9. A method for forming a magnetic random access memory (MRAM) device, the method comprising:

forming a reference magnetic region having a resultant magnetic moment vector generally maintained in a desired orientation without the use of exchange coupling thereto;

forming a storage magnetic region having an anisotropy easy axis and a resultant magnetic moment vector oriented in a position parallel or antiparallel to that of said reference magnetic region;

disposing a tunnel barrier between said reference magnetic region and said storage magnetic region;

said reference magnetic region, said storage magnetic region and said tunnel barrier defining a storage cell configured for a write operation thereto by a toggle mode; and

applying an offset field to said storage cell so as to generally maintain said resultant magnetic moment vector of said reference magnetic region in said desired orientation.

10. The method of claim 9, wherein said offset field further alters the magnitude of switching field used to perform said toggle mode write operation of said storage magnetic region.

11. The method of claim 9, further comprising configuring a bias element to generate said offset field, said bias element disposed outside a vertical stack of said storage cell.

12. The method of claim 9, wherein said bias element is configured within an array of MRAM storage elements, said array of MRAM storage elements including said storage cell.

13. The method of claim 11, wherein said bias element is configured between said storage cell and an adjacent storage cell within said array.

14. The method of claim 13, wherein said bias element is oriented at about 45 degrees with respect to a wordline and a bitline axis of said array.

15. The method of claim 14, wherein said bias element is disposed proximate corresponding tunnel barriers of said storage cell and said adjacent storage cell.

16. The method of claim 9, wherein said reference magnetic region has a coercivity of less than about 100 Oersteds (Oe).

17. The method of claim 11, further comprising at least one of:

thermally setting, patterning and planarizing said bias element prior to material deposition of said reference magnetic region, said storage magnetic region and said tunnel barrier.

18. A magnetic random access memory (MRAM) device, comprising:

a reference magnetic region having a resultant magnetic moment vector generally maintained in a desired orientation by a bias element physically separated from said reference magnetic region by a spacer layer;

a storage magnetic region having an anisotropy easy axis and a resultant magnetic moment vector oriented in a position parallel or antiparallel to that of said reference magnetic region;

a tunnel barrier disposed between said reference magnetic region and said storage magnetic region;

said reference magnetic region, said storage magnetic region and said tunnel barrier defining a storage cell configured for a write operation thereto by a toggle mode;

said bias element and said spacer layer further configured within a vertical stack of said storage cell; and

said bias element configured to generate an offset field applied to said storage cell so as to generally maintain said resultant magnetic moment vector of said reference magnetic region in said desired orientation.

19. The MRAM device of claim 18, wherein said offset field further alters the magnitude of switching field used to perform said toggle mode write operation of said storage magnetic region.

20. The MRAM device of claim 18, wherein said spacer layer is configured as a diffusion barrier between said bias element and said tunnel barrier.

21. The MRAM device of claim 18, wherein said spacer layer has a thickness of at least about 50 angstroms.

22. The MRAM device of claim 18, wherein said bias element comprises a pinned ferromagnetic material and a pinning antiferromagnetic material.

23. The MRAM device of claim 18, wherein said reference magnetic region has a coercivity of less than about 100 Oersteds (Oe).

30. The MRAM device of claim 23, wherein said reference magnetic region has a coercivity of less than about 100 Oersteds (Oe).

24. A method for forming a magnetic random access memory (MRAM) device, the method comprising:

forming a reference magnetic region having a resultant magnetic moment vector generally maintained in a desired orientation by a bias element physically separated from said reference magnetic region by a spacer layer;

forming a storage magnetic region having an anisotropy easy axis and a resultant magnetic moment vector oriented in a position parallel or antiparallel to that of said reference magnetic region;

disposing a tunnel barrier between said reference magnetic region and said storage magnetic region;

said reference magnetic region, said storage magnetic region and said tunnel barrier defining a storage cell configured for a write operation thereto by a toggle mode;

said bias element and said spacer layer further configured within a vertical stack of said storage cell; and

using said bias element to generate an offset field applied to said storage cell so as to generally maintain said resultant magnetic moment vector of said reference magnetic region in said desired orientation.

25. The method of claim 24, wherein said offset field further alters the magnitude of switching field used to perform said toggle mode write operation of said storage magnetic region.

26. The method of claim 24, wherein said spacer layer is configured as a diffusion barrier between said bias element and said tunnel barrier.

27. The method of claim 26, wherein said spacer layer has a thickness of at least about 50 angstroms.

28. The method of claim 26, wherein said bias element comprises a pinned ferromagnetic material and a pinning antiferromagnetic material.

29. The method of claim 24, further comprising at least one of:

thermally setting, patterning and planarizing said bias layer prior to material deposition of said reference magnetic region, said storage magnetic region and said tunnel barrier.