Magnetoresistive memory device including a high dielectric constant capping layer and methods of making the same
Magnetoelectric or magnetoresistive memory cells include at least one of a high dielectric constant dielectric capping layer and/or a nonmagnetic metal dust layer located between the free layer and the dielectric capping layer.
1. A method of operating a magnetoresistive memory device comprising:
providing a memory device, comprising:
a first electrode;
a second electrode;
a magnetic tunnel junction located between the first electrode and the second electrode, the magnetic tunnel junction comprising a reference layer, a free layer, and a nonmagnetic tunnel barrier layer located between the reference layer and the free layer;
a dielectric capping layer located between the second electrode and the free layer; and
a nonmagnetic metal dust layer contacting the dielectric capping layer and the free layer,
wherein the memory device comprises a spin-transfer torque (STT) magnetoresistive random access memory (MRAM) cell;
programming the MRAM cell into a first programmed state by applying a programming voltage of a first polarity such that a spin orientation in the free layer is parallel to a spin orientation of the reference layer;
programming the MRAM cell into a second programmed state by applying a programming voltage of a second polarity such that the spin orientation in the free layer is antiparallel to the spin orientation of the reference layer; and
applying a sensing voltage to the first electrode relative to the second electrode, and determining a magnitude of electrical current that tunnels through the magnetic tunnel junction,
wherein each of the positive programming voltage and the negative programming voltage has a magnitude in a range from 100 mV to 1000 mV.
2. The method of claim 1 , wherein the sensing voltage is in a range from 50 mV to 300 mV.
3. The method of claim 1 , wherein the nonmagnetic metal dust layer increases perpendicular magnetic anisotropy of the free layer.
4. The method of claim 1 , wherein the nonmagnetic metal dust layer consists essentially of at least one elemental metal.
5. The method of claim 4 , wherein the at least one elemental metal is selected from Ir, Pd, Mg, Pt, W, Ta, Hf, Pd, Ru, or Rh.
6. The method of claim 4 , wherein the at least one elemental metal is selected from Ir, Pd, Pt, W, Ta, Hf, Pd, Ru, or Rh.
7. The method of claim 4 , wherein the at least one elemental metal consists essentially of iridium.
8. The method of claim 4 , wherein the nonmagnetic metal dust layer has a thickness less than 5 monolayers of the at least one elemental metal.
9. The method of claim 1 , wherein the nonmagnetic metal dust layer is discontinuous and has sub-monolayer thickness.
10. The method of claim 1 , wherein the dielectric capping layer comprises a dielectric material selected from magnesium oxide, hafnium oxide or a ternary dielectric oxide material including at least two metal elements.
11. The method of claim 10 , wherein the dielectric capping layer consists essentially of magnesium oxide.
12. The method of claim 1 , wherein:
the dielectric capping layer has a thickness in a range from 0.2 nm to 1 nm; and
the nonmagnetic tunnel barrier layer comprises magnesium oxide and has a thickness in a range from 0.5 nm to 1.5 nm.