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;
a diffusion barrier layer disposed between the bottom metal layer and the first magnetic layer; and
a magnetic dead layer disposed between the diffusion barrier layer and the bottom metal layer and in direct contact with the diffusion barrier layer.
2. The MRAM of claim 1 , 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.
3. The MRAM of claim 2 , wherein the same element is at least one of iron, cobalt or boron.
4. The MRAM of claim 2 , wherein the same element is iron and boron.
5. 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.
6. The MRAM of claim 5 , wherein 0.50≤x≤0.70 and 0.65≤z≤0.90.
7. 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.
8. The MRAM of claim 1 , further comprising a top metal layer made of Ru and disposed over the second magnetic layer.
9. A magnetic random access memory (MRAM), comprising:
a support layer;
a bottom metal layer disposed over the support 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;
a layer made of one of magnesium, tungsten oxide, tantalum or tantalum oxide disposed between and in direct contact with the bottom metal layer and the first magnetic layer.
10. The MRAM of claim 9 , wherein the layer includes an oxide of tungsten or tantalum.
11. The MRAM of claim 9 , wherein a thickness of the layer is in a range from 0.1 nm to 0.6 nm.
12. The MRAM of claim 9 , wherein the bottom metal layer is made of one of α-W, β-W or β-Ta.
13. The MRAM of claim 9 , wherein a thickness of the bottom metal layer is in a range from 2 nm to 20 nm.
14. The MRAM of claim 9 , wherein the first magnetic layer is Fe x Co y B 1-x-y , where 0.50≤x≤0.70 and 0.65≤z≤0.90.
15. The MRAM of claim 9 , wherein the support layer includes silicon oxide.
16. A method of manufacturing a spin-orbit-torque (SOT) magnetic device, the method comprising:
forming a diffusion barrier layer over a bottom metal layer;
forming a first magnetic layer over the diffusion barrier layer;
forming a spacer layer over the first magnetic layer; and
forming a second magnetic layer over the spacer layer,
wherein the diffusion barrier layer includes an oxide by directly oxidizing the bottom metal layer.
17. The method of claim 16 , wherein a thickness of the diffusion barrier layer is in a range from 0.1 nm to 0.6 nm.
18. The method of claim 16 , wherein the diffusion barrier layer is formed by thermal oxidation, plasma oxidation or chemical oxidation.
19. The method of claim 16 , wherein the diffusion barrier layer is formed by a deposition method.
20. The method of claim 16 , wherein the diffusion barrier layer includes an oxide of tungsten or tantalum.