Magnetic tunneling junction device and memory device including the same

1 . A magnetic tunneling junction device comprising:

a free layer having a first surface and a second surface opposite the first surface;

a pinned layer facing the first surface of the free layer;

a first oxide layer between the pinned layer and the free layer; and

a second oxide layer on the second surface of the free layer,

wherein the free layer comprises a first free layer adjacent to the first oxide layer and a second free layer adjacent to the second oxide layer, and

the first free layer comprises a first magnetic material not having a non-magnetic metal incorporated into the first magnetic material of the first free layer,

the second free layer comprises a second magnetic material including the non-magnetic metal incorporated into the second magnetic material of the second free layer,

wherein the non-magnetic metal of the second free layer comprises at least one of Ru, Ir, Ti, Zn, Al, Sn, W, Sb, V, Cr, Si, Tb, Sc, Y, Rh, In, Ca, Sr, Ba, Mn, Cd, Pb, and Ga,

wherein the first oxide layer comprises a first region adjacent to the pinned layer and a second region adjacent to the free layer, and

wherein a first proportion of oxygen or nitrogen in the second region is greater than a second proportion of a respective one of oxygen or nitrogen in the first region.

2 . The magnetic tunneling junction device of claim 1 ,

wherein the first magnetic material of the first free layer and the second free layer comprises at least one of Fe, Co, Ni, Mn, a Fe-containing alloy, a Co-containing alloy, a Ni-containing alloy, a Mn-containing alloy and a Heusler alloy.

3 . The magnetic tunneling junction device of claim 2 ,

wherein the first free layer further comprises boron (B).

4 . The magnetic tunneling junction device of claim 3 ,

wherein the second free layer does not comprise boron.

5 . The magnetic tunneling junction device of claim 3 ,

wherein the second free layer comprises boron at a second concentration less than a first concentration of the first free layer.

6 . The magnetic tunneling junction device of claim 5 ,

wherein a first boron concentration of the first free layer is in a first range of about 5 at % to about 50 at %, and

a second boron concentration of the second free layer is within a second range of 0 at % to about 25 at %.

7 . The magnetic tunneling junction device of claim 5 ,

wherein the second oxide layer comprises an oxide material configured to absorb boron in the second free layer.

8 . The magnetic tunneling junction device of claim 7 ,

wherein the first concentration of boron in the first free layer is at a first peak at a first interface with the first oxide layer and gradually decreases toward the second free layer, and the second concentration of boron in the second free layer is at a second peak at a second interface with the first free layer and gradually decreases toward the second oxide layer.

9 . The magnetic tunneling junction device of claim 7 ,

wherein the second oxide layer comprises at least one selected from HfOx, NbOx, TaOx, and WOx.

10 . The magnetic tunneling junction device of claim 9 ,

wherein the second oxide layer further comprises boron absorbed from the second free layer.

11 . The magnetic tunneling junction device of claim 9 ,

wherein the first oxide layer comprises MgO and the second oxide layer does not comprise MgO.

12 . The magnetic tunneling junction device of claim 1 ,

wherein a concentration of the non-magnetic metal in the second free layer is in a range of about 5 at % to about 50 at %.

13 . The magnetic tunneling junction device of claim 1 ,

wherein the free layer further comprises a third free layer between the first free layer and the second free layer, the third free layer comprising a third magnetic material doped with a third non-magnetic metal.

14 . The magnetic tunneling junction device of claim 13 ,

wherein a second concentration of the non-magnetic metal in the second free layer is greater than a first concentration of the non-magnetic metal in the third free layer.

15 . The magnetic tunneling junction device of claim 13 ,

wherein the second free layer and the third free layer comprise different non-magnetic metals.

16 . The magnetic tunneling junction device of claim 13 ,

wherein the first free layer further comprises boron, the third free layer comprises boron at a third concentration less than a first concentration of the first free layer, and the second free layer comprises boron at a second concentration less than the third concentration of the third free layer or does not comprise boron.

17 . The magnetic tunneling junction device of claim 1 ,

wherein the first oxide layer comprises a metal oxide having a stoichiometrically oxygen-deficient composition.

18 . The magnetic tunneling junction device of claim 17 ,

wherein the first oxide layer comprises MgO, and a first proportion of Mg in the MgO of the first oxide layer is greater than 50 at % and a second proportion of O in the MgO is less than 50 at %.

19 . The magnetic tunneling junction device of claim 1 ,

wherein the first oxide layer further comprises a metal layer between the first region and the second region.

20 . The magnetic tunneling junction device of claim 1 ,

wherein the second oxide layer comprises a metal oxide having a stoichiometrically oxygen-deficient composition.

21 . The magnetic tunneling junction device of claim 1 ,

wherein a first oxygen affinity of the non-magnetic metal of the free layer is greater than a second oxygen affinity of the first magnetic material of the free layer.

22 . A magnetic tunneling junction device comprising:

a free layer having a first surface and a second surface opposite the first surface;

a pinned layer facing the first surface of the free layer;

a first oxide layer between the pinned layer and the free layer; and

a second oxide layer on the second surface of the free layer,

wherein the free layer comprises a magnetic material with a non-magnetic metal incorporated into the magnetic material, and

a concentration of the non-magnetic metal in the free layer is low at the first surface and continuously varies from the first surface along the second surface,

wherein the non-magnetic metal of the free layer comprises at least one of Ru, Ir, Ti, Zn, Al, Sn, W, Sb, V, Cr, Si, Tb, Sc, Y, Rh, In, Ca, Sr, Ba, Mn, Cd, Pb, and Ga, and

wherein the concentration of the non-magnetic metal in the free layer is peaked at a distance from the first surface between ⅔ and ⅘ of a total thickness of the free layer, and continuously and gradually decreases from a peak point in a first direction of the first surface and in a second direction of the second surface.

23 . The magnetic tunneling junction device of claim 22 ,

wherein the concentration of the non-magnetic metal in the free layer is peaked at the second surface and continuously and gradually increases from the first surface to the second surface.

24 . The magnetic tunneling junction device of claim 22 ,

wherein the free layer further comprises boron, wherein a second concentration of boron in the free layer continuously and gradually decreases from the first surface toward the second surface.

25 . A memory device comprising:

a plurality of memory cells each comprising a switching device and a magnetic tunneling junction device connected to the switching device,

wherein the magnetic tunneling junction device comprises,

a free layer having a first surface and a second surface opposite the first surface,

a pinned layer facing the first surface of the free layer,

a first oxide layer disposed between the pinned layer and the free layer, and

a second oxide layer disposed on the second surface of the free layer,

wherein the free layer comprises a first free layer adjacent to the first oxide layer and a second free layer adjacent to the second oxide layer,

the first free layer comprises a first magnetic material not having a non-magnetic metal incorporated into the first magnetic material of the first free layer, and the second free layer comprises a second magnetic material including the non-magnetic metal incorporated into the second magnetic material of the second free layer,

the non-magnetic metal of the second free layer comprises at least one of Ru, Ir, Ti, Zn, Al, Sn, W, Sb, V, Cr, Si, Tb, Sc, Y, Rh, In, Ca, Sr, Ba, Mn, Cd, Pb, and Ga,

wherein the first oxide layer comprises a first region adjacent to the pinned layer and a second region adjacent to the free layer, and

wherein a first proportion of oxygen or nitrogen in the second region is greater than a second proportion of a respective one of oxygen or nitrogen in the first region.

26 . A memory device comprising:

a plurality of memory cells each comprising a switching device and a magnetic tunneling junction device connected to the switching device,

wherein the magnetic tunneling junction device comprises,

a free layer having a first surface and a second surface opposite the first surface,

a pinned layer facing the first surface of the free layer,

a first oxide layer disposed between the pinned layer and the free layer, and

a second oxide layer disposed on the second surface of the free layer,

wherein the free layer comprises a magnetic material doped with a non-magnetic metal,

a concentration of the non-magnetic metal in the free layer is low at the first surface and continuously varies from the first surface along the second surface,

the non-magnetic metal of the free layer comprises at least one of Ru, Ir, Ti, Zn, Al, Sn, W, Sb, V, Cr, Si, Tb, Sc, Y, Rh, In, Ca, Sr, Ba, Mn, Cd, Pb, and Ga, and

wherein the concentration of the non-magnetic metal in the free layer is peaked at a distance from the first surface between ⅔ and ⅘ of a total thickness of the free layer, and continuously and gradually decreases from a peak point in a first direction of the first surface and in a second direction of the second surface.