Magnetic structures, semiconductor structures, and semiconductor devices
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 structure comprising:
a magnetic structure 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, the free region having a horizontal surface defining a smaller surface area than a surface area defined by a horizontal surface of the fixed region,
at least one of the magnetic regions comprising an alternating structure of magnetic sub-regions and coupler sub-regions, wherein the magnetic sub-regions of the alternating structure exhibit oppositely directed vertical magnetic orientations; and
a non-magnetic region between the free region and the fixed region.
2. The semiconductor structure of claim 1 , wherein each coupler sub-region of the coupler sub-regions is antiferromagnetically coupled to at least one neighboring magnetic sub-region of the magnetic sub-regions.
3. The semiconductor structure of claim 1 , wherein each of the coupler sub-regions is directly between two magnetic sub-regions.
4. The semiconductor structure of claim 1 , wherein each of the coupler sub-regions effects anti-parallel coupling in at least one neighboring magnetic sub-region.
5. The semiconductor device of claim 1 , wherein the magnetic sub-regions each define a height less than a height defined by each of the coupler sub-regions.
6. The semiconductor structure of claim 1 , wherein the fixed region comprises the alternating structure of the magnetic sub-regions and the coupler sub-regions.
7. The semiconductor structure of claim 1 , wherein each of the free region and the fixed region comprises the alternating structure of the magnetic sub-regions and the coupler sub-regions.
8. A magnetic structure comprising:
a magnetic 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, wherein the fixed region comprises a superlattice structure of the magnetic sub-regions and the coupler sub-regions; and
a non-magnetic region between the free region and the fixed region, the non-magnetic region being electrically insulative.
9. The magnetic structure of claim 8 , wherein a lateral dimension of the free region is smaller than a lateral dimension of the fixed region.
10. The magnetic structure of claim 8 , wherein the magnetic cell core is configured to emit a stronger magnetic dipole field near sidewalls of the fixed region.
11. The magnetic structure of claim 8 , wherein the free region and the fixed region comprise alternating structures of magnetic sub-regions and coupler sub-regions and the number of magnetic sub-regions in the free region is less than the number of magnetic sub-regions in the fixed region.
12. The magnetic structure of claim 8 , wherein each of the coupler sub-regions comprises ruthenium (Ru), rhodium (Rh), or combinations thereof.
13. The magnetic structure of claim 8 , wherein the fixed region is free of palladium, platinum, or combinations thereof.
14. The magnetic structure of claim 8 , wherein each of the magnetic sub-regions and the coupler sub-regions has a thickness of less than about one nanometer.
15. The magnetic structure of claim 8 , wherein the magnetic sub-regions each define a height less than a height defined by each of the coupler sub-regions.
16. The magnetic structure of claim 8 , wherein the non-magnetic region comprises a magnetic tunnel junction.
17. The magnetic structure of claim 8 , wherein the non-magnetic region comprises a spin valve.
18. The magnetic structure of claim 8 , wherein each of the magnetic sub-regions consists of cobalt.
19. A semiconductor device, comprising:
magnetic structures, each magnetic structure of the magnetic structures comprising:
at least one magnetic region comprising an alternating structure of magnetic sub-regions and coupler 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, wherein each coupler sub-region of the coupler sub-regions comprises one or more of ruthenium and rhodium.
20. The semiconductor device of claim 19 , wherein the alternating structure of magnetic sub-regions and coupler sub-regions comprises the magnetic sub-regions spaced apart from one another by the coupler sub-regions.
21. The semiconductor device of claim 19 , wherein the coupler sub-regions are thicker than the magnetic sub-regions and each magnetic sub-region of the magnetic sub-regions consists of a monolayer of the magnetic material.