PERPENDICULAR MAGNETIC TUNNEL JUNCTION (pMTJ) WITH IN-PLANE MAGNETO-STATIC SWITCHING-ENHANCING LAYER

• US 20120280339A1
• Filed: 06/15/2011
• Published: 11/08/2012
• Est. Priority Date: 02/16/2011
• Status: Active Grant

• Current Assignee: Avalanche Technology Incorporated
• Original Assignee: Avalanche Technology Incorporated
• Inventors: Zhang, Jing, Zhou, Yuchen, Ranjan, Rajiv Yadav, Huai, Yiming
• Granted Patent: US 9,196,332 B2
• Time in Patent Office: Days
• US Class Current: 257/421
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• 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: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A STTMRAM element includes a magnetic tunnel junction (MTJ) having a perpendicular magnetic orientation. The MTJ includes a barrier layer, a free layer formed on top of the barrier layer and having a magnetic orientation that is perpendicular and switchable relative to the magnetic orientation of the fixed layer. The magnetic orientation of the free layer switches when electrical current flows through the STTMRAM element. A switching-enhancing layer (SEL), separated from the free layer by a spacer layer, is formed on top of the free layer and has an in-plane magnetic orientation and generates magneto-static fields onto the free layer causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while minimally disturbing the magnetic moment at the center of the free layer to ease the switching of the free layer and to reduce the threshold voltage/current.

Claims

1. A spin transfer torque magnetic random access memory (STTMRAM) element having a perpendicular magnetic orientation and configured to store a state when electrical current is applied thereto comprising:

a seed layer;

a magnetic tunnel junction (MTJ) with a perpendicular magnetic orientation including,

a pinned layer formed on top of the seed layer and having a fixed perpendicular magnetic orientation;

a barrier layer formed on top of the pinned layer;

a free layer formed on top of the barrier layer and having a magnetic orientation that is perpendicular and switchable relative to the magnetic orientation of the fixed layer, the magnetic orientation of the free layer being operative to switch when electrical current flows through the STTMRAM element; and

a switching-enhancing layer (SEL) formed on top of the MTJ, the SEL having an in-plane magnetic orientation and being operative to generate magneto-static fields onto the free layer thereby causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while minimally disturbing the magnetic moment at the center of the free layer to ease the switching of the free layer when current flows through the STTMRAM element to switch the state thereof.

2. The STTMRAM element, as recited in claim 1, further including a spacer layer formed between the free layer and the SEL.

3. The STTMRAM element, as recited in claim 1, wherein an anti-ferromagnetic (AFM) layer is formed on top of the seed layer.

4. The STTMRAM element, as recited in claim 3, further including a bottom electrode on top of which is formed the seed layer.

5. The STTMRAM element, as recited in claim 4, further including a cap layer formed on top of the SEL.

6. The STTMRAM element, as recited in claim 1, wherein the free layer switches from anti-parallel magnetic orientation to a parallel magnetic orientation relative to that of the pinned layer.

7. The STTMRAM element, as recited in claim 1, wherein the free layer switches from a parallel magnetic orientation to anti-parallel magnetic orientation relative to that of the pinned layer.

8. The STTMRAM element, as recited in claim 1, wherein the SEL is made of a single layer.

9. The STTMRAM element, as recited in claim 1, wherein the SEL is made of multiple layers.

10. The STTMRAM element, as recited in claim 1, wherein the SEL is made of a ferromagnetic material.

11. The STTMRAM element, as recited in claim 1, wherein the SEL is made of a first ferromagnetic material formed on top of the seed layer, a second spacer layer formed on top of the first ferromagnetic layer and a second ferromagnetic layer formed on top of the spacer layer.

12. The STTMRAM element, as recited in claim 1, wherein the SEL is made of a first ferromagnetic layer and a second ferromagnetic layer that is formed on top of the first ferromagnetic layer where each of the first and second ferromagnetic layers have a unique saturation magnetization (Ms).

13. The STTMRAM element, as recited in claim 1, wherein the SEL is made of a first ferromagnetic layer and a second ferromagnetic layer that is formed on top of the first ferromagnetic layer where each of the first and second ferromagnetic layers have a unique magnetic isotropy (Hk).

14. The STTMRAM element, as recited in claim 1, wherein the SEL is made of an anti-ferromagnetic layer and a ferromagnetic layer.

15. The STTMRAM element, as recited in claim 1, wherein the SEL is made of an anti-ferromagnetic layer, a first ferromagnetic layer, a non-magnetic spacer layer, and a second ferromagnetic layer with the first ferromagnetic layer formed on top of the anti-ferromagnetic layer, the non-magnetic spacer layer formed on top of the first magnetic layer and the second ferromagnetic layer formed on top of the non-magnetic spacer layer.

16. The STTMRAM element, as recited in claim 2, wherein the spacer layer is a bilayer including a metal layer and an insulator layer.

17. The STTMRAM element, as recited in claim 16, wherein the insulator layer is formed on top of the metal layer.

18. The STTMRAM element, as recited in claim 16, wherein the metal layer is formed on top of the insulator layer.

19. The STTMRAM element, as recited in claim 2, wherein the spacer layer is an insulating layer.

20. The STTMRAM element, as recited in claim 2, wherein the spacer layer is a metal layer.

21. The STTMRAM element, as recited in claim 20, wherein the metal layer is made of Ta, Ti, Ru, Pt, Cr, Cu, or Hf.

22. The STTMRAM element, as recited in claim 1, wherein the pinned layer is made of Co, iron or Ni or an alloy made from a combination thereof or from Co, Fe, Ni or X or any combination thereof and where “

X”

is Xis one or a combination of non-magnetic elements such as chromium (Cr), platinum (Pt), tantalum (Ta), titanium (Ti), tungsten (W), boron (B), or vanadium (V), niobium (Nb), nickel (Ni), molybdenum (Mo), tungsten (W), silicon (Si), copper(Cu), aluminum (Al), gallium (Ga), platimum (Pt), paladium (Pd), samarium (Sm), oxygen (O), and nitrogen (N).

23. The STTMRAM element, as recited in claim 1, wherein the SEL is made of cobolt (Co), iron or nitride (Ni) or an alloy made from a combination thereof or from Co, Fe, Ni or X or any combination thereof and where “

X”

is X is one or a combination of non-magnetic elements such as chromium (Cr), platinum (Pt), tantalum (Ta), titanium (Ti), tungsten (W), boron (B), or vanadium (V), niobium (Nb), nickel (Ni), molybdenum (Mo), tungsten (W), silicon (Si), copper (Cu), aluminum (Al), gallium (Ga), platimum (Pt), paladium (Pd), samarium (Sm), oxygen (O), and nitrogen (N).

24. A spin transfer torque magnetic random access memory (STTMRAM) element having a perpendicular magnetic orientation and configured to store a state when electrical current is applied thereto comprising:

a seed layer;

a magnetic tunnel junction (MTJ) with a perpendicular magnetic orientation including,

a free layer formed on top of the seed layer and having a switchable perpendicular magnetic orientation;

a barrier layer formed on top of the free layer;

a pinned layer formed on top of the barrier layer and having a fixed magnetic orientation that is perpendicular,

the magnetic orientation of the free layer being switchable relative to the magnetic orientation of the fixed layer and being operative to switch when electrical current flows through the STTMRAM element; and

a switching-enhancing layer (SEL) formed between the seed layer and the MTJ, the SEL having an in-plane magnetic orientation and being operative to generate magneto-static fields onto the free layer thereby causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while minimally disturbing the magnetic moment at the center of the free layer to ease the switching of the free layer when current flows through the STTMRAM element to switch the state thereof.

25. The STTMRAM element, as recited in claim 24, further including a spacer layer formed between the free layer and the SEL.

26. The STTMRAM element, as recited in claim 24, wherein an anti-ferromagnetic (AFM) layer is formed on top of the seed layer.

27. The STTMRAM element, as recited in claim 26, further including a bottom electrode on top of which is formed the seed layer.

28. The STTMRAM element, as recited in claim 27, further including a cap layer formed on top of the SEL.

29. The STTMRAM element, as recited in claim 24, wherein the free layer switches from anti-parallel magnetic orientation to a parallel magnetic orientation relative to that of the pinned layer.

30. The STTMRAM element, as recited in claim 24, wherein the free layer switches from a parallel magnetic orientation to anti-parallel magnetic orientation relative to that of the pinned layer.

31. The STTMRAM element, as recited in claim 24, wherein the SEL is made of a single layer.

32. The STTMRAM element, as recited in claim 24, wherein the SEL is made of multiple layers.

33. The STTMRAM element, as recited in claim 24, wherein the SEL is made of a ferromagnetic material.

34. The STTMRAM element, as recited in claim 24, wherein the SEL is made of a first ferromagnetic material formed on top of the seed layer, a second spacer layer formed on top of the first ferromagnetic layer and a second ferromagnetic layer formed on top of the spacer layer.

35. The STTMRAM element, as recited in claim 24, wherein the SEL is made of a first ferromagnetic layer and a second ferromagnetic layer that is formed on top of the first ferromagnetic layer where each of the first and second ferromagnetic layers have a unique saturation magnetization (Ms).

36. The STTMRAM element, as recited in claim 24, wherein the SEL is made of a first ferromagnetic layer and a second ferromagnetic layer that is formed on top of the first ferromagnetic layer where each of the first and second ferromagnetic layers have a unique magnetic isotropy (Hk).

37. The STTMRAM element, as recited in claim 24, wherein the SEL is made of an anti-ferromagnetic layer and a ferromagnetic layer.

38. The STTMRAM element, as recited in claim 24, wherein the SEL is made of an anti-ferromagnetic layer, a first ferromagnetic layer, a non-magnetic spacer layer, and a second ferromagnetic layer with the first ferromagnetic layer formed on top of the anti-ferromagnetic layer, the non-magnetic spacer layer formed on top of the first magnetic layer and the second ferromagnetic layer formed on top of the non-magnetic spacer layer.

39. The STTMRAM element, as recited in claim 25, wherein the spacer layer is a bilayer including a metal layer and an insulator layer.

40. The STTMRAM element, as recited in claim 39, wherein the insulator layer is formed on top of the metal layer.

41. The STTMRAM element, as recited in claim 39, wherein the metal layer is formed on top of the insulator layer.

42. The STTMRAM element, as recited in claim 25, wherein the spacer layer is an insulating layer.

43. The STTMRAM element, as recited in claim 25, wherein the spacer layer is a metal layer.

44. The STTMRAM element, as recited in claim 43, wherein the metal layer is made of Ta, Ti, Ru, Pt, Cr, Cu, or Hf.

45. The STTMRAM element, as recited in claim 24, wherein the pinned layer is made of Co, iron or Ni or an alloy made from a combination thereof or from Co, Fe, Ni or X or any combination thereof and where “

X”

is Xis one or a combination of non-magnetic elements such as chromium (Cr), platinum (Pt), tantalum (Ta), titanium (Ti), tungsten (W), boron (B), or vanadium (V), niobium (Nb), nickel (Ni), molybdenum (Mo), tungsten (W), silicon (Si), copper(Cu), aluminum (Al), gallium(Ga), platimum (Pt), Paladium(Pd), samarium (Sm), oxygen (O), and nitrogen (N).

46. The STTMRAM element, as recited in claim 24, wherein the SEL is made of cobolt (Co), iron or nitride (Ni) or an alloy made from a combination thereof or from Co, Fe, Ni or X or any combination thereof and where “

X”

is X is one or a combination of non-magnetic elements such as chromium (Cr), platinum (Pt), tantalum (Ta), titanium (Ti), tungsten (W), boron (B), or vanadium (V), niobium (Nb), nickel (Ni), molybdenum (Mo), tungsten (W), silicon (Si), copper (Cu), aluminum (Al), gallium (Ga), platimum (Pt), paladium (Pd), samarium (Sm), oxygen (O), and nitrogen (N).

47. A spin torque transfer magnetic random access memory (STTMRAM) element having a perpendicular magnetic orientation and configured to store a state when electrical current is applied thereto comprising:

a seed layer;

a magnetic tunnel junction (MTJ) with a perpendicular magnetic orientation including,

a free layer formed on top of the seed layer;

a barrier layer formed on top of the free layer;

a pinned layer formed on top of the barrier layer,

the free layer having a magnetic orientation that is perpendicular relative to the film plane and switchable relative to the magnetic orientation of the fixed layer, the magnetic orientation of the free layer being operative to switch when electrical current flows through the STTMRAM element; and

a first switching-enhancing layer (SEL) formed on a side of the MTJ;

a first spacer layer on top of which the first SEL is formed;

a second SEL formed on an opposite side of the MTJ;

a second spacer layer on top of which the second SEL is formed, each of the first spacer layer, second spacer layer, first SEL and second SEL being separated from the MTJ by an insulating layer, where each of the first and second SELs having an in-plane magnetic orientation and operative to generate magneto-static fields onto the free layer thereby causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while maintaining the magnetic moment at the center of the free layer to ease the switching of the free layer when current flows through the STTMRAM element to switch the state thereof.

48. The STTMRAM element, as recited in claim 47, further including an anti-ferromagnetic layer formed on top of the pinned layer.

49. The STTMRAM element, as recited in claim 47, further including a cap layer formed on top of the AFM layer.

50. A spin torque transfer magnetic random access memory (STTMRAM) element having a perpendicular magnetic orientation and configured to store a state when electrical current is applied thereto comprising:

a seed layer;

a magnetic tunnel junction (MTJ) with a perpendicular magnetic orientation including,

a pinned layer formed on top of the seed layer;

a barrier layer formed on top of the pinned layer;

a free layer formed on top of the barrier layer,

the free layer having a magnetic orientation that is perpendicular relative to the film plane and switchable relative to the magnetic orientation of the fixed layer, the magnetic orientation of the free layer being operative to switch when electrical current flows through the STTMRAM element; and

a first switching-enhancing layer (SEL) formed on a side of the MTJ;

a first spacer layer on top of which the first SEL is formed;

a second SEL formed on an opposite side of the MTJ;

a second spacer layer on top of which the second SEL is formed, each of the first spacer layer, second spacer layer, first SEL and second SEL being separated from the MTJ by an insulating layer, where each of the first and second SELs having an in-plane magnetic orientation and operative to generate magneto-static fields onto the free layer thereby causing the magnetic moments of the outer edges of the free layer to tilt with an in-plane component while maintaining the magnetic moment at the center of the free layer to ease the switching of the free layer when current flows through the STTMRAM element to switch the state thereof.

51. The STTMRAM element, as recited in claim 50, further including an anti-ferromagnetic layer formed on top of the pinned layer.

52. The STTMRAM element, as recited in claim 50, further including a cap layer formed on top of the AFM layer.