Magnetoresistive device comprising chromium
The disclosed technology generally relates to a magnetoresistive device and more particularly to a magnetoresistive device comprising chromium. According to an aspect, a method of forming a magnetoresistive device comprises forming a magnetic tunnel junction (MTJ) structure over a substrate. The MTJ structure includes, in a bottom-up direction away from the substrate, a free layer, a tunnel barrier layer and a reference layer. The method additionally includes forming a pinning layer over the MTJ structure, wherein the pinning layer pins a magnetization direction of the reference layer. The method additionally includes forming capping layer comprising chromium (Cr) over the pinning layer. The method further includes annealing the capping layer under a condition sufficient to cause diffusion of Cr from the capping layer into at least the pinning layer. According to another aspect, a magnetoresistive device is formed according to the method.
1. A magnetoresistive device, comprising:
a magnetic tunnel junction (MTJ) structure formed over a substrate, the MTJ structure comprising, in a bottom-up direction away from the substrate, a free layer, a tunnel barrier layer and a reference layer;
a pinning layer formed of a material comprising chromium (Cr) and formed above the reference layer, wherein the pinning layer pins a magnetization direction of the reference layer; and
a capping layer comprising Cr formed above the pinning layer, wherein a concentration profile of Cr in the pinning layer is a diffusion profile resulting from diffusion of Cr from the capping layer as a source of Cr into the pinning layer, wherein the diffusion profile extends from the capping layer.
2. The magnetoresistive device according to claim 1 , wherein a concentration of Cr in the pinning layer is lower than a concentration of Cr in the capping layer.
3. The magnetoresistive device according to claim 1 , wherein the capping layer comprises one or more monolayers of Cr.
4. The magnetoresistive device according to claim 1 , wherein the capping layer further comprises one or more monolayers of a second element different from Cr.
5. The magnetoresistive device according to claim 4 , wherein the one more monolayers of Cr and the one or more monolayers of the second element alternate in the bottom-up direction.
6. The magnetoresistive device according to claim 4 , wherein the second element is an element selected from the group consisting of Ni, Ta, Pt, Pd, Tb, Gd, W, Mo, Ru, Bi, Hf, Fe, Co, Ti, and V.
7. The magnetoresistive device according to claim 1 , wherein the pinning layer comprises a hard magnetic layer.
8. The magnetoresistive device according to claim 1 , wherein each of the free layer and the reference layer comprises a CoFeB layer.
9. The magnetoresistive device according to claim 1 , wherein the diffusion profile extends through the pinning layer and into the reference layer, such that an amount of Cr decreases in a downward direction towards the substrate that is characteristic of a diffusion profile.
10. The magnetoresistive device according to claim 1 , wherein the pinning layer comprise a plurality of layers each comprising a ferromagnetic material, and wherein the capping layer is formed as a topmost one of the plurality of layers contacting a top electrode.
11. A magnetoresistive device, comprising:
a magnetic tunnel junction (MTJ) structure comprising a tunnel barrier layer interposed between a free layer and a reference layer;
a pinning layer formed of a material comprising chromium (Cr) and formed over the reference layer, wherein the pinning layer and the reference layer have the same magnetization direction; and
a capping layer comprising Cr formed above the pinning layer, wherein a concentration profile of Cr in the pinning layer is a diffusion profile resulting from diffusion of Cr from the capping layer as a source of Cr into the pinning layer, wherein the diffusion profile extends from the capping layer.
12. The magnetoresistive device according to claim 11 , wherein the capping layer has a concentration of Cr that is higher than a concentration of Cr in the pinning layer.
13. The magnetoresistive device according to claim 11 , wherein the reference layer is formed of a material comprising Cr.
14. The magnetoresistive device according to claim 13 , wherein the capping layer has a concentration of Cr that is higher than a concentration of Cr in the reference layer.
15. The magnetoresistive device according to claim 11 , further comprising a spacer layer interposed between the reference layer and the pinning layer, the spacer layer comprising an element selected from the group consisting of W, Ta, Mo, Pt, Hf, V and Bi.
16. The magnetoresistive device according to claim 11 , wherein the capping layer comprises one or more monolayers of Cr.
17. The magnetoresistive device according to claim 16 , wherein the capping layer further comprises one or more monolayers of a second element different from Cr.
18. The magnetoresistive device according to claim 17 , wherein the one more monolayers of Cr alternate with the one or more monolayers of the second element.
19. The magnetoresistive device according to claim 17 , wherein the second element is a metal selected from the group consisting of Ni, Ta, Pt, Pd, Tb, Gd, W, Mo, Ru, Bi, Hf, Fe, Co, Ti, and V.
20. The magnetoresistive device according to claim 11 , wherein the diffusion profile extends from the capping layer, through the pinning layer and into the reference layer, such that an amount of Cr decreases in a downward direction towards the substrate that is characteristic of a diffusion profile.