Magnetic random access memory (MRAM) having increased reference layer anisotropy through ion beam etch of magnetic layers
View Patent ↗A Magnetic Random Access Memory (MRAM) cell and array for storing data. The MRAM array includes a memory cell having a magnetic pinned layer, a magnetic free layer and a non-magnetic spacer or barrier layer sandwiched between the pinned and free layer. The pinned layer has magnetization that is pinned, and the free layer has a magnetization that is free to rotate but is stable in directions that are parallel or antiparallel with the magnetization of the pinned layer. The free layer has a magnetic anisotropy the maintains the stability of the free layer magnetization. The free layer anisotropy is induced by a surface roughness either in the surface of the free layer itself, or in the surface of the underling barrier/spacer layer. This anisotropic roughness is induced by an angled direct ion milling.
1. A magnetic memory cell for use in a Magnetic Random
Access Memory (MRAM) Array, comprising:
a first magnetic layer, the first magnetic layer being a pinned magnetic layer;
a second magnetic layer having a surface that has an anisotropic texture;
a non-magnetic layer sandwiched between the first and second magnetic layers;
a layer of antiferromagnetic material (AFM layer) exchange coupled with the first magnetic layer and wherein the surface of the AFM layer has an anisotropic surface texture that induces a magnetic anisotropy in the first magnetic layer.
2. A magnetic memory cell as in claim 1 , wherein the non-magnetic layer is an electrically insulating barrier layer.
3. A magnetic memory cell as in claim 1 , wherein the non-magnetic layer is an electrically conductive spacer layer.
4. A magnetic memory cell as in claim 1 wherein the first magnetic layer has a first magnetization that is pinned in a first direction, and the second magnetic layer has a magnetic anisotropy that is substantially parallel with the first direction.
5. A magnetic memory cell as in claim 1 wherein the first magnetic layer is a pinned magnetic layer structure comprising first and second magnetic sub-layers and a non-magnetic anti-parallel coupling layer sandwiched between the first and second magnetic sub-layers, and wherein a surface of the pinned layer structure has an anisotropic surface texture that induces a magnetic anisotropy in the pinned layer structure.
6. A magnetic memory cell as in claim 1 wherein the first magnetic layer is a pinned magnetic layer structure comprising first and second magnetic sub-layers and a non-magnetic anti-parallel coupling layer sandwiched between the first and second magnetic sub-layers, and wherein a surface of the first and second sub-layer has an anisotropic surface texture that induces a magnetic anisotropy in the pinned layer structure.
7. A Magnetic Random Access Memory (MRAM) array, comprising:
an electrically conductive word line;
an electrically conductive bit line;
a magnetic memory cell sandwiched between the word line and the bit line, the magnetic memory cell further comprising:
a first magnetic layer;
a second magnetic layer; and
a non-magnetic layer sandwiched between the first and second magnetic layers; and wherein
the non-magnetic layer has a surface configured with an anisotropic texture that induces a magnetic anisotropy in the second magnetic layer.
8. A magnetic memory cell as in claim 7 wherein the first magnetic layer is a pinned magnetic layer structure comprising first and second magnetic sub-layers and a non-magnetic anti-parallel coupling layer sandwiched between the first and second magnetic sub-layers.
9. A magnetic memory cell for use in a Magnetic Random Access Memory (MRAM) Array, comprising:
a first magnetic layer;
a second magnetic layer having a surface that has an anisotropic texture; and
a non-magnetic layer sandwiched between the first and second magnetic layers;
wherein the first magnetic layer is a pinned layer structure comprising first and second magnetic sub-layers separated by a non-magnetic antiparallel coupling layer, and wherein the pinned layer is formed on an underlayer that has a anisotropic surface texture that induces a magnetic anisotropy in the pinned layer.
10. A magnetic memory cell for use in a Magnetic Random Access Memory (MRAM) Array, comprising:
a first magnetic layer;
a second magnetic layer having a surface that has an anisotropic texture; and
a non-magnetic layer sandwiched between the first and second magnetic layers;
wherein the first magnetic layer has a magnetic coercivity that is larger than that of the second magnetic layer, and wherein the first magnetic layer is formed on an under-layer that has an anisotropic texture that induces a magnetic anisotropy in the first magnetic layer.