Semiconductor devices comprising magnetic memory cells
Memory cells are disclosed. Magnetic regions within the memory cells include an alternating structure of magnetic sub-regions and coupler sub-regions. The coupler material of the coupler sub-regions antiferromagnetically couples neighboring magnetic sub-regions and effects or encourages a vertical magnetic orientation exhibited by the neighboring magnetic sub-regions. Neighboring magnetic sub-regions, spaced from one another by a coupler sub-region, exhibit oppositely directed magnetic orientations. The magnetic and coupler sub-regions may each be of a thickness tailored to form the magnetic region in a compact structure. Interference between magnetic dipole fields emitted from the magnetic region on switching of a free region in the memory cell may be reduced or eliminated. Also disclosed are semiconductor device structures, spin torque transfer magnetic random access memory (STT-MRAM) systems, and methods of fabrication.
1. A semiconductor device comprising at least one magnetic memory cell, the at least one magnetic memory cell comprising:
a magnetic cell core comprising:
magnetic regions, the magnetic regions comprising:
a free region exhibiting a switchable vertical magnetic orientation; and
a fixed region exhibiting a fixed vertical magnetic orientation,
at least one of the magnetic regions comprising an alternating structure of magnetic sub-regions and coupler sub-regions, the magnetic sub-regions each defining a height less than a height defined by each of the coupler sub-regions, neighboring magnetic sub-regions of the alternating structure exhibiting oppositely directed magnetic orientations; and
a non-magnetic region between the free region and the fixed region.
2. The semiconductor device of claim 1 , wherein the non-magnetic region is electrically insulative.
3. The semiconductor device of claim 1 , wherein each of the coupler sub-regions is directly between a pair of the magnetic sub-regions.
4. The semiconductor device of claim 1 , wherein the fixed region comprises the alternating structure of the magnetic sub-regions and the coupler sub-regions.
5. The semiconductor device of claim 4 , the magnetic regions further comprising another fixed region exhibiting a fixed vertical magnetic orientation and comprising the alternating structure of the magnetic sub-regions and the coupler sub-regions.
6. The semiconductor device of claim 5 , wherein the fixed region and the another fixed region are symmetrically disposed above and below, respectively, the free region.
7. The semiconductor device of claim 1 , wherein the free region does not comprise the alternating structure of the magnetic sub-regions and the coupler sub-regions.
8. The semiconductor device of claim 1 , wherein all of the magnetic regions of the magnetic cell core comprise the alternating structure of the magnetic sub-regions and the coupler sub-regions.
9. The semiconductor device of claim 1 , wherein the free region has a horizontal surface defining a smaller surface area than a surface area defined by a horizontal surface of the fixed region.
10. A semiconductor device, comprising:
an array of magnetic memory cells, at least one magnetic memory cell of the array comprising:
at least one magnetic region comprising an alternating structure of magnetic sub-regions and coupler sub-regions thicker than the magnetic sub-regions, magnetic material of the at least one magnetic region exhibiting a vertical magnetic orientation, neighboring magnetic sub-regions of the alternating structure being antiferromagnetically coupled with one another.
11. The semiconductor device of claim 10 , wherein each of the magnetic sub-regions consists of a monolayer of the magnetic material.
12. The semiconductor device of claim 10 , wherein:
one of the magnetic sub-regions is an uppermost sub-region of the alternating structure; and
another of the magnetic sub-regions is a lowermost sub-region of the alternating structure.
13. The semiconductor device of claim 10 , wherein the magnetic sub-regions of the alternating structure comprise:
magnetic sub-regions exhibiting a vertical magnetic orientation directed in a first vertical direction; and
magnetic sub-regions exhibiting a vertical magnetic orientation directed in a second vertical direction opposite the first vertical direction,
the magnetic sub-regions exhibiting the vertical magnetic orientation directed in the first vertical direction being thicker than the magnetic sub-regions exhibiting the vertical magnetic orientation directed in the second vertical direction.
14. The semiconductor device of claim 13 , wherein the at least one magnetic memory cell of the array further comprises a reference region exhibiting a vertical magnetic orientation in the second vertical direction.
15. The semiconductor device of claim 10 , wherein the magnetic sub-regions consist essentially of cobalt.
16. A semiconductor device, comprising:
an array of spin torque transfer magnetic random access memory (STT-MRAM) cells, at least one STT-MRAM cell thereof comprising:
a magnetic region exhibiting a fixed vertical magnetic orientation, the magnetic region comprising magnetic sub-regions interleaved with coupler sub-regions in an alternating structure, each of the coupler sub-regions having a greater height than a height of each of the magnetic sub-regions, neighboring magnetic sub-regions of the alternating structure exhibiting oppositely directed magnetic orientations;
another magnetic region exhibiting a switchable vertical magnetic orientation; and
an oxide region between the magnetic region and the another magnetic region,
a bit line and a word line in operable communication with the at least one STT-MRAM cell.
17. The semiconductor device of claim 16 , wherein the magnetic sub-regions comprise up to five monolayers of cobalt.
18. The semiconductor device of claim 16 , wherein the coupler sub-regions comprise at least one of ruthenium or rhodium.
19. The semiconductor device of claim 16 , wherein the magnetic region is free of palladium and platinum.