Magnetic memory cells, methods of fabrication, semiconductor devices, memory systems, and electronic systems
A magnetic cell includes a free region between an intermediate oxide region (e.g., a tunnel barrier) and a secondary oxide region. Both oxide regions may be configured to induce magnetic anisotropy (“MA”) with the free region, enhancing the MA strength of the free region. A getter material proximate to the secondary oxide region is formulated and configured to remove oxygen from the secondary oxide region, reducing an oxygen concentration and an electrical resistance of the secondary oxide region. Thus, the secondary oxide region contributes only minimally to the electrical resistance of the cell core. Embodiments of the present disclosure therefore enable a high effective magnetoresistance, low resistance area product, and low programming voltage along with the enhanced MA strength. Methods of fabrication, memory arrays, memory systems, and electronic systems are also disclosed.
1. A memory cell, comprising:
a magnetic cell core comprising:
a magnetic region exhibiting a switchable magnetic orientation;
another magnetic region exhibiting a fixed magnetic orientation;
an intermediate oxide region between the magnetic region and the another magnetic region;
another oxide region directly adjacent the magnetic region and spaced from the intermediate oxide region by the magnetic region, the another oxide region consisting of magnesium oxide and having lower electrical resistance than the intermediate oxide region; and
a getter region proximate to the another oxide region and spaced from the magnetic region, the getter region consisting of oxygen and a getter material consisting of at least one of calcium, strontium, aluminum, barium, or zirconium.
2. The memory cell of claim 1 , wherein the intermediate oxide region is formed from magnesium oxide.
3. The memory cell of claim 2 , wherein the another oxide region has a lower oxygen concentration than the intermediate oxide region.
4. The memory cell of claim 1 , wherein the getter region is directly adjacent to the another oxide region.
5. The memory cell of claim 1 , wherein the getter region is internal to the another oxide region.
6. The memory cell of claim 5 , wherein the another oxide region comprises an upper oxide sub-region and a lower oxide sub-region, the getter region disposed between the upper oxide sub-region and the lower oxide sub-region.
7. The memory cell of claim 1 , wherein the getter material is calcium.
8. The memory cell of claim 1 , wherein at least one of the magnetic region and the another magnetic region comprises sub-regions of magnetic material.
9. A method of forming a magnetic memory cell, comprising:
forming a magnetic cell core, comprising:
forming a magnetic region between an intermediate oxide region and another oxide material, the another oxide material consisting of magnesium oxide, the magnetic region exhibiting a switchable magnetic orientation;
forming another magnetic region adjacent the intermediate oxide region, the another magnetic region exhibiting a fixed magnetic orientation, the intermediate oxide region disposed between the magnetic region and the another magnetic region;
forming a getter material proximate to the another oxide material, the getter material consisting of at least one of calcium, strontium, aluminum, barium, or zirconium; and
transferring oxygen from the another oxide material to the getter material to decrease an electrical resistance of the another oxide material, to form another oxide region from the another oxide material, and to form a getter region from the getter material, the another oxide region directly adjacent the magnetic region and spaced from the intermediate oxide region by the magnetic region, the another oxide region having lower electrical resistance than the intermediate oxide region, the getter region proximate to the another oxide region and spaced from the magnetic region, the getter region consisting of the oxygen and the getter material.
10. The method of claim 9 , wherein forming a magnetic region and forming a getter material comprise:
forming a getter material over a substrate;
forming the another oxide material over the getter material;
forming the magnetic region over the another oxide material; and
forming the intermediate oxide region over the magnetic region.
11. The method of claim 9 , wherein forming a getter material proximate to the another oxide material comprises:
forming a lower oxide sub-region of the another oxide region;
forming the getter material over the lower oxide sub-region; and
forming an upper oxide sub-region of the another oxide region over the getter material.
12. The method of claim 9 , wherein forming a magnetic region and forming a getter material comprise:
forming the intermediate oxide region over a substrate;
forming the magnetic region over the intermediate oxide region;
forming the another oxide material over the magnetic region; and
forming the getter material over the another oxide material.
13. The method of claim 9 , wherein transferring oxygen from the another oxide material to the getter material comprises annealing the another oxide material and the getter material.
14. The method of claim 9 , wherein transferring oxygen from the another oxide material to the getter material comprises transferring a portion of the oxygen from the another oxide material to the getter material.
15. The method of claim 9 , wherein forming a getter material proximate the another oxide material comprises sputtering the getter material.
16. A spin torque transfer magnetic random access memory (STT-MRAM) system, comprising:
STT-MRAM cells, at least one STT-MRAM cell of the STT-MRAM cells comprising:
a pair of magnetic regions, comprising:
a magnetic region exhibiting a switchable magnetic orientation; and
another magnetic region exhibiting a fixed magnetic orientation; and
a pair of oxide regions, comprising:
an intermediate oxide region between the magnetic region and the another magnetic region; and
another oxide region directly adjacent a surface of the magnetic region opposite an interface between the intermediate oxide region and the magnetic region, the another oxide region having lower electrical resistance than the intermediate oxide region and consisting of magnesium oxide; and
a getter region proximate to the another oxide region and spaced from the magnetic region, the getter region consisting of oxygen and a metal selected from the group consisting of calcium, strontium, aluminum, barium, and zirconium;
at least one peripheral device in operable communication with the at least one STT-MRAM cell; and
at least one of an access transistor, a bit line, a word line, and a source line in operable communication with at least one STT-MRAM cell.
17. The STT-MRAM system of claim 16 , wherein an electrical resistance of the another oxide region is less than 50% an electrical resistance of the intermediate oxide region.
18. A semiconductor device, comprising:
a spin torque transfer magnetic random access memory (STT-MRAM) array comprising:
STT-MRAM cells, at least one STT-MRAM cell of the SIT-MRAM cells comprising:
an intermediate oxide region between a free region and a fixed region;
another oxide region consisting of magnesium oxide and directly adjacent the free region and spaced from the intermediate oxide region, the another oxide region having a lower electrical resistance than the intermediate oxide region; and
a getter region proximate the another oxide region and consisting of oxygen and a metal selected from the group consisting of calcium, strontium, aluminum, barium, and zirconium.
19. The semiconductor device of claim 18 , wherein the at least one STT-MRAM cell is configured as an out-of-plane STT-MRAM cell.
20. An electronic system, comprising:
at least one processor coupled to system memory, the system memory comprising:
at least one magnetic memory cell comprising:
a fixed region exhibiting a fixed magnetic orientation;
an intermediate oxide region adjacent to the fixed region;
a free region adjacent to the intermediate oxide region, the free region exhibiting a switchable magnetic orientation;
another oxide region directly adjacent to the free region and spaced from the intermediate oxide region by the free region, the another oxide region consisting of magnesium oxide; and
a getter material proximate to the another oxide region and spaced from the free region, the getter material consisting of oxygen and a metal selected from the group consisting of calcium, strontium, aluminum, barium, and zirconium; and
a power supply in operable communication with the at least one processor.
21. The memory cell of claim 1 . wherein the another oxide region is directly between the magnetic region and the getter region.