Magnetic memory cells, semiconductor devices, and methods of operation
A magnetic cell core includes at least one stressor structure proximate to a magnetic region (e.g., a free region or a fixed region). The magnetic region may be formed of a magnetic material exhibiting magnetostriction. During switching, the stressor structure may be subjected to a programming current passing through the magnetic cell core. In response to the current, the stressor structure may alter in size. Due to the size change, the stressor structure may exert a stress upon the magnetic region and, thereby, alter its magnetic anisotropy. In some embodiments, the MA strength of the magnetic region may be lowered during switching so that a lower programming current may be used to switch the magnetic orientation of the free region. In some embodiments, multiple stressor structures may be included in the magnetic cell core. Methods of fabrication and operation and related device structures and systems are also disclosed.
1. A magnetic memory cell, comprising:
a cell core comprising:
a free region to one side of a nonmagnetic region;
a fixed region to another side of the nonmagnetic region;
a stressor structure adjacent the free region and configured to expand or to contract, in response to a programming current, to exert a stress upon the free region; and
another stressor structure adjacent the fixed region and configured to expand or to contract, in response to the programming current, to exert another stress upon the fixed region.
2. The magnetic memory cell of claim 1 , wherein both of the free region and the fixed region comprise a magnetic material exhibiting positive magnetostriction.
3. The magnetic memory cell of claim 1 , wherein:
one of the free region and the fixed region comprises a magnetic material exhibiting positive magnetostriction; and
another of the free region and the fixed region comprises another magnetic material exhibiting negative magnetostriction.
4. The magnetic memory cell of claim 3 , wherein:
the free region comprises the magnetic material exhibiting the positive magnetostriction; and
the fixed region comprises the another magnetic material exhibiting the negative magnetostriction.
5. The magnetic memory cell of claim 3 , wherein:
the fixed region comprises the magnetic material exhibiting the positive magnetostriction; and
the free region comprises the another magnetic material exhibiting the negative magnetostriction.
6. The magnetic memory cell of claim 1 , wherein the stressor structure and the another stressor structure are both configured to expand in response to the programming current.
7. The magnetic memory cell of claim 1 , wherein:
one of the stressor structure and the another stressor structure is configured to expand in response to the programming current; and
another of the stressor structure and the another stressor structure is configured to contract in response to the programming current.
8. The magnetic memory cell of claim 1 :
wherein the nonmagnetic region comprises an electrically insulative oxide material; and
further comprising another oxide region adjacent to the free region.
9. The magnetic memory cell of claim 8 , wherein the stressor structure separates the another oxide region from the free region.
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 disposed between a lower electrode below and an upper electrode above, the magnetic cell core comprising:
a nonmagnetic region directly between a free region and a fixed region, the free region exhibiting a switchable magnetic orientation, the fixed region exhibiting a fixed magnetic orientation;
a stressor structure adjacent the free region and configured to, during programming of the at least one magnetic memory cell, alter in size to exert a stress upon the free region; and
another stressor structure adjacent the fixed region and configured to, during programming of the at least one magnetic memory cell, alter in size to exert a stress upon the fixed region.
11. The semiconductor device of claim 10 , wherein at least one of the stressor structure or the another stressor structure comprises a piezoelectric material.
12. The semiconductor device of claim 10 , wherein:
the free region exhibits a vertical switchable magnetic orientation and comprises a magnetic material exhibiting positive magnetostriction; and
the stressor structure is configured to, during programming of the at least one magnetic memory cell, vertically expand to exert a vertical compressive stress upon the free region.
13. The semiconductor device of claim 12 , wherein:
the fixed region exhibits a vertical fixed magnetic orientation and comprises another magnetic material exhibiting positive magnetostriction; and
the another stressor structure is configured to, during programming of the at least one magnetic memory cell, vertically contract to exert a vertical tensile stress upon the fixed region.
14. The semiconductor device of claim 12 , wherein:
the fixed region exhibits a vertical fixed magnetic orientation and comprises another magnetic material exhibiting negative magnetostriction; and
the another stressor structure is configured to, during programming of the at least one magnetic memory cell, vertically expand to exert a vertical compressive stress upon the fixed region.
15. The semiconductor device of claim 10 , wherein:
the fixed region exhibits a horizontal fixed magnetic orientation and comprises a magnetic material exhibiting positive magnetostriction; and
the another stressor structure is configured to, during programming of the at least one magnetic memory cell, vertically expand to exert a vertical compressive stress upon the fixed region.
16. The semiconductor device of claim 15 , wherein:
the free region exhibits a horizontal switchable magnetic orientation and comprises another magnetic material exhibiting negative magnetostriction; and
the stressor structure is configured to, during programming of the at least one magnetic memory cell, vertically expand to exert a vertical compressive stress upon the free region.
17. The semiconductor device of claim 15 , wherein:
the free region exhibits a horizontal switchable magnetic orientation and comprises another magnetic material exhibiting positive magnetostriction; and
the stressor structure is configured to, during programming of the at least one magnetic memory cell, vertically contract to exert a vertical tensile stress upon the free region.
18. A method of operating a semiconductor device comprising a magnetic cell core comprising a stressor structure adjacent a free region and comprising another stressor structure adjacent a fixed region, the method comprising:
passing a programming current between an upper electrode and a lower electrode, the magnetic cell core extending between the lower electrode below and the upper electrode above, the programming current altering a size of the stressor structure to exert a stress upon the free region, and the programming current altering a size of the another stressor structure to exert a stress upon the fixed region; and
halting the passage of the programming current, the stressor structure and the another stressor structure reverting in size in the absence of the programming current.
19. The method of claim 18 , wherein passing a programming current between an upper electrode and a lower electrode comprises passing the programming current to increase the size of the stressor structure and to decrease the size of the another stressor structure.
20. The method of claim 18 , wherein passing a programming current between an upper electrode and a lower electrode comprises passing the programming current to increase the size of the stressor structure and to increase the size of the another stressor structure.