Magnetic memory cells, semiconductor devices, and methods of formation
A magnetic cell includes magnetic, secondary oxide, and getter seed regions. During formation, a diffusive species is transferred from a precursor magnetic material to the getter seed region, due to a chemical affinity elicited by a getter species. The depletion of the magnetic material enables crystallization of the depleted magnetic material through crystal structure propagation from a neighboring crystalline material, without interference from the now-enriched getter seed region. This promotes high tunnel magnetoresistance and high magnetic anisotropy strength. Also during formation, another diffusive species is transferred from a precursor oxide material to the getter seed region, due to a chemical affinity elicited by another getter species. The depletion of the oxide material enables lower electrical resistance and low damping in the cell structure. Methods of fabrication and semiconductor devices are also disclosed.
1. A magnetic memory cell, comprising:
a magnetic tunnel junction sub-structure comprising a nonmagnetic intermediate region between at least two magnetic regions;
an oxide region proximate to the magnetic tunnel junction sub-structure and thinner than the nonmagnetic intermediate region of the magnetic tunnel junction sub-structure; and
a getter region proximate to the oxide region and comprising boron and oxygen, wherein the getter region is physically isolated from the magnetic tunnel junction sub-structure.
2. The magnetic memory cell of claim 1 , wherein the oxide region is directly adjacent a free region of the magnetic tunnel junction sub-structure.
3. The magnetic memory cell of claim 1 , wherein magnetic regions of the magnetic tunnel junction sub-structure exhibit out-of-plane magnetic orientations.
4. The magnetic memory cell of claim 1 , wherein the getter region further comprises nitrogen.
5. The magnetic memory cell of claim 1 , wherein the oxide region has a maximum oxygen concentration along an interface with the magnetic tunnel junction sub-structure.
6. The magnetic memory cell of claim 1 , wherein the oxide region comprises boron.
7. The magnetic memory cell of claim 1 , wherein the oxide region is nonmagnetic.
8. The magnetic memory cell of claim 1 , wherein the getter region further comprises at least one boron-getter species bonded to the boron and selected from the group consisting of tantalum (Ta), ruthenium (Ru), tungsten (W), aluminum (Al), titanium (Ti), zirconium (Zr), nitrogen (N), hafnium (Hf), and nickel (Ni).
9. The magnetic memory cell of claim 1 , wherein the getter region further comprises at least one oxygen-getter species bonded to the oxygen and selected from the group consisting of calcium (Ca), strontium (Sr), beryllium (Be), lanthanum (La), barium (Ba), aluminum (Al), and magnesium (Mg).
10. A semiconductor device, comprising:
an array of magnetic memory cells, at least one magnetic memory cell of the array comprising a magnetic cell core comprising:
a magnetic tunnel junction sub-structure comprising a magnetic region exhibiting a switchable magnetic orientation, the magnetic region comprising cobalt and iron;
an amorphous getter region comprising boron, a boron-getter species, oxygen, and an oxygen-getter species; and
a nonmagnetic region directly between the magnetic region and the amorphous getter region, the nonmagnetic region comprising a maximum concentration of oxygen along an interface with the magnetic region.
11. The semiconductor device of claim 10 , wherein the magnetic tunnel junction sub-structure further comprises:
another magnetic region exhibiting a substantially fixed magnetic orientation; and
an intermediate oxide region vertically between the another magnetic region above and the magnetic region below.
12. The semiconductor device of claim 10 , wherein the boron-getter species is a conductive metal.
13. The semiconductor device of claim 10 , wherein the magnetic tunnel junction sub-structure further comprises an intermediate oxide region of a greater thickness than a thickness of the nonmagnetic region.
14. The semiconductor device of claim 10 , wherein the nonmagnetic region further comprises boron and another boron-getter species.
15. The semiconductor device of claim 14 , wherein the another boron-getter species is a different element than the boron-getter species of the amorphous getter region.
16. A method for forming a magnetic memory cell, comprising:
forming a precursor structure comprising:
forming a precursor getter seed material over a substrate, the precursor getter seed material comprising an oxygen-getter species and another getter species;
forming a precursor oxide material directly on the precursor getter seed material; and
forming a precursor magnetic material directly on the precursor oxide material;
annealing the precursor structure to transfer oxygen from the precursor oxide material, to bond the oxygen to the oxygen-getter species, to transfer a diffusive species from the precursor magnetic material, and to bond the diffusive species to the another getter species; and
patterning the precursor structure, after the anneal, to form at least a portion of a magnetic cell core of a magnetic memory cell, the portion of the magnetic cell core comprising:
a magnetic region of a magnetic tunnel junction sub-structure and comprising the precursor magnetic material at least partially depleted of the diffusive species;
an amorphous getter region comprising the oxygen-getter species, the oxygen transferred from the precursor oxide material, the another getter species, and the diffusive species transferred from the precursor magnetic material; and
a secondary oxide region directly between the magnetic region and the amorphous getter region, the secondary oxide region comprising the precursor oxide material at least partially depleted of the oxygen.
17. The method of claim 16 , wherein:
forming a precursor oxide material comprises forming a precursor oxide material comprising an additional getter species; and
further comprising, during the annealing, transferring an additional amount of the diffusive species from the precursor magnetic material to bond the diffusive species to the additional getter species.
18. The method of claim 16 , wherein:
forming a precursor oxide material directly on the precursor getter seed material comprises forming the precursor oxide material directly above the precursor getter seed material; and
forming a precursor magnetic material directly on the precursor oxide material comprises forming the precursor magnetic material directly above the precursor oxide material.
19. The method of claim 16 , further comprising, after the annealing and before the patterning, forming another magnetic material over the precursor magnetic material at least partially depleted of the diffusive species.
20. A magnetic memory cell, comprising:
a magnetic tunnel junction sub-structure comprising a nonmagnetic intermediate region between at least two magnetic regions;
an oxide region proximate to the magnetic tunnel junction sub-structure and thinner than the nonmagnetic intermediate region of the magnetic tunnel junction sub-structure; and
a getter region proximate to the oxide region and comprising boron and oxygen, wherein the magnetic regions of the magnetic tunnel junction sub-structure exhibit out-of-plane magnetic orientations.
21. A magnetic memory cell, comprising:
a magnetic tunnel junction sub-structure comprising a nonmagnetic intermediate region between at least two magnetic regions;
an oxide region proximate to the magnetic tunnel junction sub-structure and thinner than the nonmagnetic intermediate region of the magnetic tunnel junction sub-structure; and
a getter region proximate to the oxide region and comprising boron, oxygen, and nitrogen.
22. A magnetic memory cell, comprising:
a magnetic tunnel junction sub-structure comprising a nonmagnetic intermediate region between at least two magnetic regions;
an oxide region proximate to the magnetic tunnel junction sub-structure and thinner than the nonmagnetic intermediate region of the magnetic tunnel junction sub-structure; and
a getter region proximate to the oxide region and comprising boron and oxygen, wherein the oxide region comprises boron.
23. A magnetic memory cell, comprising:
a magnetic tunnel junction sub-structure comprising a nonmagnetic intermediate region between at least two magnetic regions;
an oxide region proximate to the magnetic tunnel junction sub-structure and thinner than the nonmagnetic intermediate region of the magnetic tunnel junction sub-structure; and
a getter region proximate to the oxide region and comprising boron and oxygen, wherein the getter region further comprises at least one oxygen-getter species bonded to the oxygen and selected from the group consisting of calcium (Ca), strontium (Sr), beryllium (Be), lanthanum (La), barium (Ba), aluminum (Al), and magnesium (Mg).