Magnetic tunnel junction having diffusion stop layer
View Patent ↗Magnetic or magnetoresistive tunnel junctions (MTJs) having diffusion stop layers to eliminate or reduce diffusion of oxygen, nitrogen or other particles from the barrier layer to the ferromagnetic layers during the film deposition process including the barrier oxidation or nitridation process and the post annealing process. Such MTJs may be used in various applications including magnetic memory (MRAM) devices and magnetic recording heads.
1. A device, comprising:
a substrate;
first and second magnetic layers formed over the substrate, wherein the first magnetic layer is located between the substrate and the second magnetic layer;
an insulator barrier layer formed between the first and second magnetic layers to effectuate tunneling of electrons between the first and second magnetic layers under a bias voltage applied between the first and second magnetic layers and across the insulator barrier layer;
a diffusion stop layer formed between the first magnetic layer and the insulator barrier layer to permit the tunneling and prevent diffusion of particles from the insulator barrier layer into the first magnetic layer,
wherein the first magnetic layer is a magnetically pinned ferromagnetic layer whose magnetization is fixed in a first direction, and the second magnetic layer is a free ferromagnetic layer whose magnetization is controllable to be either substantially parallel to or substantially opposite to the fixed magnetization of the first ferromagnetic layer;
a second insulator barrier layer formed above the second ferromagnetic layer;
a second diffusion stop layer formed between the second ferromagnetic layer and the second insulator barrier layer to prevent diffusion of particles from the second insulator barrier layer into the second ferromagnetic layer;
a third ferromagnetic layer formed above the second insulator barrier layer and magnetically pinned,
wherein the second insulator barrier layer and the second diffusion stop layer are structured to effectuate tunneling of electrons between the second and the third ferromagnetic layers under a second bias voltage applied between the second and the third ferromagnetic layers; and
a third diffusion stop layer formed between the second ferromagnetic layer and the first insulator barrier layer to permit the tunneling and to prevent diffusion of particles from the first insulator baffler layer into the second ferromagnetic layer.
2. The device as in claim 1 , further comprising:
a first antiferromagnetic (AFM) layer next to the first ferromagnetic layer to pin the magnetization of the first ferromagnetic layer; and
a second antiferromagnetic (AFM) layer next to the third ferromagnetic layer to pin the magnetization of the third ferromagnetic layer.
3. The device as in claim 2 , wherein the pinned magnetization direction of first ferromagnetic later and the pinned magnetization direction of third ferromagnetic layer are substantially anti parallel to each other.
4. The device as in claim 3 , further comprising a current control mechanism to supply and control a variable and polarized current perpendicularly flowing between the first and the third ferromagnetic layers to change the direction of the second magnetization, thus altering a first resistance between the first and the second ferromagnetic layers and a second resistance between the second and the third ferromagnetic layers.
5. The device as in claim 1 , further comprising a control mechanism to produce a variable control magnetic field to change the direction of the second magnetization, thus altering a first resistance between the first and the second ferromagnetic layers and a second resistance between the second and the third ferromagnetic layers.
6. The device as in claim 1 , further comprising a current control mechanism to supply and control a variable and polarized current perpendicularly flowing between the first and the third ferromagnetic layers to change the direction of the second magnetization, thus altering a first resistance between the first and the second ferromagnetic layers and a second resistance between the second and the third ferromagnetic layers.
7. A device, comprising:
a substrate;
first and second magnetic layers formed over the substrate, wherein the first magnetic layer is located between the substrate and the second magnetic layer;
an insulator barrier layer formed between the first and second magnetic layers to effectuate tunneling of electrons between the first and second magnetic layers under a bias voltage applied between the first and second magnetic layers and across the insulator barrier layer;
a diffusion stop layer formed between the first magnetic layer and the insulator barrier layer to permit the tunneling and prevent diffusion of particles from the insulator barrier layer into the first magnetic layer,
wherein the first magnetic layer is a magnetically pinned ferromagnetic layer whose magnetization is fixed in a first direction, and the second magnetic layer is a free ferromagnetic layer whose magnetization is controllable to be either substantially parallel to or substantially opposite to the fixed magnetization of the first ferromagnetic layer;
a second insulator barrier layer formed above the second ferromagnetic layer;
a second diffusion stop layer formed between the second ferromagnetic layer and the second insulator barrier layer to prevent diffusion of particles from the second insulator barrier layer into the second ferromagnetic layer;
a third ferromagnetic layer formed above the second insulator barrier layer and magnetically pinned,
wherein the second insulator barrier layer and the second diffusion stop layer are structured to effectuate tunneling of electrons between the second and the third ferromagnetic layers under a second bias voltage applied between the second and the third ferromagnetic layers; and
a third diffusion stop layer formed between the third ferromagnetic layer and the second insulator barrier layer to permit the tunneling and to prevent diffusion of particles from the second insulator barrier layer into the third ferromagnetic layer.
8. A device, comprising:
a substrate;
first and second magnetic layers formed over the substrate, wherein the first magnetic layer is located between the substrate and the second magnetic layer;
an insulator barrier layer formed between the first and second magnetic layers to effectuate tunneling of electrons between the first and second magnetic layers under a bias voltage applied between the first and second magnetic layers and across the insulator barrier layer; and
a diffusion stop layer formed between the first magnetic layer and the insulator barrier layer to permit the tunneling and prevent diffusion of particles from the insulator barrier layer into the first magnetic layer,
wherein the first magnetic layer is a magnetically pinned ferromagnetic layer whose magnetization is fixed in a first direction, and the second magnetic layer is a free ferromagnetic layer whose magnetization is controllable to be either substantially parallel to or substantially opposite to the fixed magnetization of the first ferromagnetic layer,
the device further comprising:
a non-magnetic metal spacer layer formed above the second ferromagnetic layer; and
a third ferromagnetic layer on the non-magnetic metal spacer layer and magnetically pinned to have a fixed third magnetization.
9. The device as in claim 8 , wherein the diffusion stop layer is between 0.5 to 50 angstroms.
10. The device as in claim 8 , wherein the diffusion stop layer is between 0.5 to 3 angstroms.
11. The device as in claim 8 , wherein the diffusion stop layer comprises an oxide.
12. The device as in claim 11 , wherein the oxide comprises a chromium oxide.
13. The device as in claim 11 , wherein the oxide comprises a hafnium oxide.
14. The device as in claim 11 , wherein the oxide comprises a zirconium oxide.
15. The device as in claim 11 , wherein the oxide comprises a tantalum oxide.
16. The device as in claim 11 , wherein the oxide comprises a molybdenum oxide.
17. The device as in claim 11 , wherein the oxide comprises a titanium oxide.
18. The device as in claim 8 , wherein the insulator barrier layer comprises a first nitride and the diffusion stop layer comprises a second nitride.
19. The device as in claim 8 , wherein the insulator barrier layer comprises an aluminum oxide.
20. The device as in claim 8 , wherein the insulator barrier layer comprises a magnesium oxide.
21. The device as in claim 8 , wherein the first magnetic layer is ferromagnetic and is a magnetically pinned layer whose magnetization is fixed in a first direction and the second magnetic layer is ferromagnetic and is a free layer whose magnetization is controllable to be either substantially parallel to or substantially opposite to the fixed first magnetization.
22. The device as in claim 21 , further comprising a control mechanism to produce a variable control magnetic field to change the direction of the second magnetization, thus altering a resistance between the first and the second ferromagnetic layers.
23. The device as in claim 21 , further comprising a current control mechanism to supply and control a variable and polarized current perpendicularly flowing between the first and second ferromagnetic layers to change the direction of the second magnetization, thus altering a resistance between the first and the second ferromagnetic layers.
24. The device as in claim 8 , wherein the second magnetic layer is ferromagnetic and is a magnetically pinned layer whose magnetization is fixed in a second direction and the first magnetic layer is a free ferromagnetic layer whose magnetization is controllable to be either substantially parallel to or substantially opposite to the fixed second magnetization.
25. The device as in claim 24 , further comprising a control mechanism to produce a variable control magnetic field to change the direction of the first magnetization, thus altering a resistance between the first and the second ferromagnetic layers.
26. The device as in claim 24 , further comprising a current control mechanism to supply and control a variable and polarized current perpendicularly flowing between the first and second ferromagnetic layers to change the direction of the first magnetization, thus altering a resistance between the first and the second ferromagnetic layers.
27. The device as in claim 8 , further comprising a second diffusion stop layer formed between the second magnetic layer and the insulator baffler layer to permit the tunneling and to prevent diffusion of particles from the insulator barrier layer into the second magnetic layer.
28. The device as in claim 8 , further comprising:
a first antiferromagnetic (AFM) layer next to the first ferromagnetic layer to pin the magnetization of the first ferromagnetic layer; and
a second antiferromagnetic (AFM) layer next to the third ferromagnetic layer to pin the magnetization of the third ferromagnetic layer.
29. The device as in claim 8 , further comprising a second diffusion stop layer formed between the second ferromagnetic layer and the insulator barrier layer to permit the tunneling and to prevent diffusion of particles from the insulator baffler layer into the second ferromagnetic layer.
30. The device as in claim 8 , further comprising a current control mechanism to supply and control a variable and polarized current perpendicularly flowing between the first and the third ferromagnetic layers to change the direction of the second magnetization, thus altering a resistance between the first and the second ferromagnetic layers.
31. The device as in claim 8 , further comprising a second diffusion stop layer formed between the second ferromagnetic layer and the insulator barrier layer.
32. The device as in claim 8 , wherein at least one of the first and second magnetic layers comprises at least two sublayers.
33. The device as in claim 8 , wherein the first and second magnetic layers are ferrimagnetic layers.
34. The device as in claim 8 , wherein the first and second magnetic layers are half-metal magnetic layers.
35. The device as in claim 8 , wherein each magnetic layer includes a combined layer of a ferromagnetic and a ferrimagnetic layer.
36. The device as in claim 8 , wherein each magnetic layer includes a combined layer of a ferromagnetic and a half-metal layer.
37. The device as in claim 8 , wherein each magnetic layer includes two sublayers of ferromagnetic or ferrimagnetic or half-metal magnetic materials and a spacer between the two sublayers.
38. The devices as in claim 37 , wherein the spacer comprises Ru.
39. The devices as in claim 37 , wherein two sublayers are different in thickness.
40. The device as in claim 8 , wherein the diffusion stop layer comprises a nitride.
41. The device as in claim 40 , wherein the nitride comprises a titanium nitride.
42. The device as in claim 40 , wherein the insulator barrier layer comprises an aluminum nitride.
43. The device as in claim 40 , wherein the insulator barrier layer comprises an aluminum nitride.
44. A device, comprising:
a substrate;
first and second magnetic layers formed over the substrate, wherein the first magnetic layer is located between the substrate and the second magnetic layer;
an insulator barrier layer formed between the first and second magnetic layers to effectuate tunneling of electrons between the first and second magnetic layers under a bias voltage applied between the first and second magnetic layers and across the insulator barrier layer; and
a diffusion stop layer formed between the first magnetic layer and the insulator barrier layer to permit the tunneling and prevent diffusion of particles from the insulator barrier layer into the first magnetic layer
wherein the diffusion stop layer comprises a chromium nitride, a vanadium nitride, an iron nitride or a magnesium nitride.