Magnetic memory element

Patent metadata

Field	Value
Publication number	US-8928055-B2
Application number	US-201213601343-A
Country	US
Kind code	B2
Filing date	Aug 31, 2012
Priority date	Mar 20, 2012
Publication date	Jan 6, 2015
Grant date	Jan 6, 2015

Abstract

According to one embodiment, a magnetic memory element includes a stacked body and a conductive shield. The stacked body includes first and second stacked units. The first stacked unit includes first and second ferromagnetic layers and a first nonmagnetic layer. The first ferromagnetic layer has a fixed magnetization in a first direction. A magnetization direction of the second ferromagnetic layer is variable in a second direction. The first nonmagnetic layer is provided between the first and second ferromagnetic layers. The second stacked unit includes a third ferromagnetic layer stacked with the first stacked unit in a stacking direction of the first stacked unit. A magnetization direction of the third ferromagnetic layer is variable in a third direction. The conductive shield is opposed to at least a part of a side surface of the second stacked unit. An electric potential of the conductive shield is controllable.

First claim

What is claimed is:

1. A magnetic memory element comprising:
a stacked body including:
a first stacked unit including:
a first ferromagnetic layer, a magnetization of the first ferromagnetic layer being fixed in a first direction;
a second ferromagnetic layer, a direction of a magnetization of the second ferromagnetic layer being variable in a second direction; and
a first nonmagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer, the first nonmagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer being stacked in a stacking direction; and

a second stacked unit including a third ferromagnetic layer stacked with the first stacked unit in the stacking direction, a direction of a magnetization of the third ferromagnetic layer being variable in a third direction; and
a conductive shield opposed to at least a part of a side surface of the second stacked unit, an electric potential of the conductive shield being controllable.

2. The element according to claim 1 , wherein the second stacked unit further includes a second nonmagnetic layer provided between the first stacked unit and the third ferromagnetic layer.

3. The element according to claim 1 , wherein the second stacked unit further includes:
a fourth ferromagnetic layer stacked with the third ferromagnetic layer in the stacking direction, a magnetization of the fourth ferromagnetic layer being fixed in a fourth direction; and
a second nonmagnetic layer provided between the third ferromagnetic layer and the fourth ferromagnetic layer.

4. The element according to claim 3 , further comprising
a first conductive layer; and
a second conductive layer,
the first stacked unit being disposed between the first conductive layer and the second conductive layer,
the second stacked unit being disposed between the first stacked unit and the second conductive layer,
the first conductive layer being electrically connected to one of the first ferromagnetic layer and the second ferromagnetic layer,
the second conductive layer being electrically connected to one of the third ferromagnetic layer and the fourth ferromagnetic layer, and
the conductive shield being electrically isolated from the first conductive layer and from the second conductive layer.

5. The element according to claim 3 , further comprising
a first conductive layer;
a second conductive layer; and
a shield interconnection electrically connected to the shield and being isolated from the first conductive layer and from the second conductive layer,
the first stacked unit being disposed between the first conductive layer and the second conductive layer,
the second stacked unit being disposed between the first stacked unit and the second conductive layer,
the first conductive layer being electrically connected to one of the first ferromagnetic layer and the second ferromagnetic layer, and
the second conductive layer being electrically connected to one of the third ferromagnetic layer and the fourth ferromagnetic layer.

6. The element according to claim 3 , wherein
the first direction has a first component parallel to the stacking direction,
the fourth direction has a second component parallel to the stacking direction, and
a direction of the first component is opposite to a direction of the second component.

7. The element according to claim 3 , wherein
the first ferromagnetic layer, the second ferromagnetic layer, and the fourth ferromagnetic layer are perpendicular magnetization films, and
the third ferromagnetic layer is an in-plane magnetization film.

8. The element according to claim 1 , wherein the shield includes a magnetic substance.

9. The element according to claim 1 , wherein
the stacked body further includes a third nonmagnetic layer provided between the first stacked unit and the second stacked unit, and
the third nonmagnetic layer includes one metal selected from the group consisting of ruthenium (Ru), tantalum (Ta), tungsten (W), platinum (Pt), palladium (Pd), molybdenum (Mo), niobium (Nb), zirconium (Zr), titanium (Ti), and vanadium (V) or an alloy including at least two metals selected from the group.

10. The element according to claim 9 , wherein a circle-equivalent diameter of a cross-sectional shape of the third ferromagnetic layer obtained by cutting along a plane perpendicular to the stacking direction is not more than 35 nanometers and a thickness of the third ferromagnetic layer is not less than 0.5 nanometers and not more than 3.5 nanometers.

11. The element according to claim 1 , wherein
the stacked body further includes a third nonmagnetic layer provided between the first stacked unit and the second stacked unit,
the third nonmagnetic layer includes one metal selected from the group consisting of ruthenium (Ru), osmium (Os), and iridium (Ir) or an alloy including at least two metals selected from the group, and
a thickness of the third nonmagnetic layer is not more than 3 nanometers.

12. The element according to claim 1 , further comprising a shield interconnection electrically connected to the shield.

13. The element according to claim 12 , wherein the shield interconnection is connected to a terminal at a ground potential or a power supply potential.

14. The element according to claim 12 , further comprising
a first conductive layer; and
a second conductive layer,
the first stacked unit being disposed between the first conductive layer and the second conductive layer,
the second stacked unit being disposed between the first stacked unit and the second conductive layer,
the first conductive layer being electrically connected to one of the first ferromagnetic layer and the second ferromagnetic layer,
the second conductive layer being electrically connected to the third ferromagnetic layer, and
the shield interconnection being electrically isolated from the first conductive layer and from the second conductive layer.

15. The element according to claim 1 , wherein the shield is further opposed to a side surface of the first stacked unit.

16. The element according to claim 1 , wherein the shield includes one selected from the group consisting of gold (Au), copper (Cu), chromium (Cr), zinc (Zn), gallium (Ga), niobium (Nb), molybdenum (Mo), ruthenium (Ru), palladium (Pd), silver (Ag), hafnium (Hf), tantalum (Ta), titanium (Ti), tungsten (W), platinum (Pt), bismuth (Bi), vanadium (V), zirconium (Zr), magnesium (Mg), silicon (Si), and aluminum (Al).

17. The element according to claim 1 , wherein the shield includes a metal selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium (Cr) or an alloy including two or more metals selected from the group.

18. The element according to claim 1 , wherein the shield includes an alloy including
at least one metal selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium (Cr) and
at least one metal selected from the group consisting of platinum (Pt), palladium (Pd), iridium (Ir), ruthenium (Ru), and rhodium (Rh).

19. The element according to claim 1 , wherein the shield includes at least one of a TbFeCo alloy, a GdFeCo alloy, a Co/Pt stacked film, a Co/Pd stacked film, and a Co/Ni stacked film.

20. The element according to claim 1 , further comprising an insulative protection layer provided between the side surface and the shield.

21. The element according to claim 20 , wherein the protection layer includes an oxide, a nit

Assignees

• Saida Daisuke
• Amano Minoru
• Ito Junichi
• Toshiba Kk

Inventors

• Saida Daisuke
• Amano Minoru
• Ito Junichi

Classifications

• G11C11/161

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• G11C11/1659 Primary

  Cell access · CPC title

• H10N50/10 Primary

  Magnetoresistive devices · CPC title

• H10N50/01

  Manufacture or treatment · CPC title

• H10B61/22

  of the field-effect transistor [FET] type · CPC title