Magnetic device and magnetic random access memory
A spin-orbit-torque (SOT) magnetic device includes a bottom metal layer, a first magnetic layer disposed over the bottom metal layer, a spacer layer disposed over the first magnetic layer, and a second magnetic layer disposed over the spacer layer. A diffusion barrier layer for suppressing metal elements of the first magnetic layer from diffusing into the bottom metal layer is disposed between the bottom metal layer and the first magnetic layer.
1. A magnetic random access memory (MRAM), comprising:
a bottom metal layer;
a first magnetic layer disposed over the bottom metal layer;
a spacer layer disposed over the first magnetic layer;
a second magnetic layer disposed over the spacer layer; and
a diffusion barrier layer disposed between the bottom metal layer and the first magnetic layer,
wherein the diffusion barrier layer and the first magnetic layer includes a same element, and
an atomic percentage of the same element in the diffusion barrier layer is higher than an atomic percentage of the same element in the first magnetic layer.
2. The MRAM of claim 1 , wherein the same element is at least one of iron, cobalt or boron.
3. The MRAM of claim 1 , wherein the same element is iron and boron.
4. The MRAM of claim 1 , wherein:
the first magnetic layer is Fe x Co y B 1-x-y , and
the diffusion barrier layer is Fe z B 1-z , where z>x.
5. The MRAM of claim 4 , wherein 0.50≤x≤0.70 and 0.65≤z≤0.90.
6. The MRAM of claim 1 , wherein a thickness of the diffusion barrier layer is in a range from 0.1 nm to 0.6 nm.
7. The MRAM of claim 1 , further comprising a top metal layer made of Ru and disposed over the second magnetic layer.
8. The MRAM of claim 1 , wherein the second magnetic layer includes iron, cobalt and boron.
9. A magnetic random access memory (MRAM), comprising:
a bottom metal layer;
a first magnetic layer disposed over the bottom metal layer;
a spacer layer disposed over the first magnetic layer;
a second magnetic layer disposed over the spacer layer;
an intermediate metal layer disposed between the spacer layer and the second magnetic layer; and
a diffusion barrier layer disposed between the bottom metal layer and the first magnetic layer,
wherein the intermediate metal layer is made of magnesium.
10. The MRAM of claim 9 , wherein the diffusion barrier layer is made of one of magnesium, tungsten oxide, tantalum or tantalum oxide.
11. The MRAM of claim 9 , wherein a thickness of the intermediate metal layer is in a range from 0.1 nm to 0.6 nm.
12. The MRAM of claim 9 , wherein the spacer layer is made of magnesium oxide.
13. The MRAM of claim 9 , wherein a thickness of the diffusion barrier layer is in a range from 0.1 nm to 0.6 nm.
14. The MRAM of claim 9 , wherein the bottom metal layer is made of one of α-W, β-W or β-Ta.
15. The MRAM of claim 9 , wherein a thickness of the bottom metal layer is in a range from 2 nm to 20 nm.
16. A method of manufacturing a spin-orbit-torque (SOT) magnetic device, the method comprising:
forming a first magnetic layer over a bottom metal layer;
forming a spacer layer over the first magnetic layer; and
forming a second magnetic layer over the spacer layer,
wherein the method further comprising forming a diffusion barrier layer between the first magnetic layer and the bottom metal layer,
wherein the diffusion barrier layer and the first magnetic layer includes a same element.
17. The method of claim 16 , wherein the diffusion barrier layer is formed by, after the first magnetic layer is formed, performing a thermal annealing.
18. The method of claim 17 , wherein a process temperature of the thermal annealing is in a range from 350° C. to 450° C.
19. The method of claim 17 , wherein a process time of the thermal annealing is in a range from 30 min to 240 min.
20. The method of claim 16 , wherein the diffusion barrier layer is formed by, after the first magnetic layer is formed, performing a plasm treatment on the first magnetic layer.