Method and system for providing a low moment free layer magnetic junction usable in spin transfer torque applications

Patent metadata

Field	Value
Publication number	US-9876164-B1
Application number	US-201615367014-A
Country	US
Kind code	B1
Filing date	Dec 1, 2016
Priority date	Oct 1, 2016
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A magnetic junction and method for providing the magnetic junction are described. The magnetic junction resides on a substrate and is usable in a magnetic device. The magnetic junction includes free and pinned layers separated by a nonmagnetic spacer layer. The free layer is switchable between stable magnetic states when a write current is passed through the magnetic junction. The free layer has a free layer perpendicular magnetic anisotropy energy greater than a free layer out-of-plane demagnetization energy. The free layer includes an alloy. The alloy includes [Co x Fe y B z ] u Mg t , where u+t=1 and x+y+z=1.

First claim

We claim:

1. A magnetic junction residing on a substrate and usable in a magnetic device comprising:
a pinned layer;
a nonmagnetic spacer layer; and
a free layer, the free layer being switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction, the nonmagnetic spacer layer residing between the pinned layer and the free layer, the free layer having a free layer perpendicular magnetic anisotropy energy greater than a free layer out-of-plane demagnetization energy, the free layer including an alloy, the alloy including [Co x Fe y B z ] u Mg t , where u+t=1 and x+y+z=1 and wherein u, t, x, y and z are each nonzero.

2. The magnetic junction of claim 1 wherein the free layer includes at least one of a CoFeB/[Co x Fe y B z ] u Mg t /Fe trilayer, a [Co x Fe y B z ] u Mg t /Fe bilayer; and a CoFeB/[Co x Fe y B z ] u Mg t bilayer.

3. The magnetic junction of claim 1 where t is not more than 0.35 and at least 0.15.

4. The magnetic junction of claim 1 wherein the alloy is a [Co x Fe y B z ] u Mg t layer, the [Co x Fe y B z ] u Mg t layer having a thickness of at least three Angstroms and not more than twenty Angstroms.

5. The magnetic junction of claim 4 wherein the thickness is not more than fifteen Angstroms.

6. The magnetic junction of claim 1 wherein the nonmagnetic spacer layer includes MgO and adjoins the free layer.

7. The magnetic junction of claim 1 further comprising:
a seed layer adjoining the free layer, the seed layer including at least one of a magnesium oxide layer, a tantalum oxide layer and a titanium oxide layer.

8. The magnetic junction of claim 1 wherein the nonmagnetic spacer layer is between the free layer and the substrate and wherein the magnetic junction further includes a capping layer, the capping layer including at least one of a magnesium oxide layer, a tantalum oxide layer, a magnesium oxide/tantalum oxide bilayer and a titanium oxide layer.

9. The magnetic junction of claim 1 further comprising:
an additional nonmagnetic spacer layer, the free layer being between the additional nonmagnetic spacer layer and the nonmagnetic spacer layer; and
an additional pinned layer, the additional nonmagnetic spacer layer being between the additional pinned layer and the free layer.

10. A magnetic memory residing on a substrate and comprising:
a plurality of magnetic storage cells, each of the plurality of magnetic storage cells including at least one magnetic junction including a pinned layer, a nonmagnetic spacer layer and a free layer, the free layer being switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction, the nonmagnetic spacer layer residing between the pinned layer and the free layer, the free layer having a free layer perpendicular magnetic anisotropy energy greater than a free layer out-of-plane demagnetization energy, the free layer including an alloy, the alloy including [Co x Fe y B z ] u Mg t , where u+t=1 and x+y+z=1, and wherein u, t, x, y and z are each nonzero, the free layer including at least one of a CoFeB/[Co x Fe y B z ] u Mg t /Fe trilayer, a [Co x Fe y B z ] u Mg t /Fe bilayer; and a CoFeB/[Co x Fe y B z ] u Mg t bilayer;
a plurality of bit lines coupled with the plurality of magnetic storage cells.

11. A method for providing magnetic junction residing on a substrate and usable in a magnetic device, the method comprising:
providing a pinned layer;
providing a nonmagnetic spacer layer, and
providing a free layer, the free layer being switchable between a plurality of stable magnetic states when a write current is passed through the magnetic junction, the nonmagnetic spacer layer residing between the pinned layer and the free layer, the free layer having a free layer perpendicular magnetic anisotropy energy greater than a free layer out-of-plane demagnetization energy, the free layer including a [Co x Fe y B z ] u Mg t layer, where u+t=1 and x+y+z=1 and wherein u, t, x, y and z are each nonzero.

12. The method of claim 11 wherein the step of providing the free layer includes:
providing at least one of a CoFeB/[Co x Fe y B z ] u Mg t /Fe trilayer, a [Co x Fe y B z ] u Mg t /Fe bilayer; and a CoFeB/[Co x Fe y B z ] u Mg t bilayer.

13. The method of claim 11 wherein t is not more than 0.35 and at least 0.15.

14. The method of claim 11 wherein the [Co x Fe y B z ] u Mg t layer has a thickness of at least three Angstroms and not more than twenty Angstroms.

15. The method of claim 11 further comprising:
providing a seed layer adjoining the free layer, the seed layer including at least one of a magnesium oxide layer, a tantalum oxide layer and a titanium oxide layer; and
cooling the MgO layer to below twenty three degrees Celsius before providing the free layer.

16. The method of claim 11 wherein the nonmagnetic spacer layer is between the free layer and the substrate and wherein the method further includes:
providing a capping layer, the capping layer including at least one of a magnesium oxide layer, a tantalum oxide layer, a magnesium oxide/tantalum oxide bilayer and a titanium oxide layer.

17. The method of claim 11 further comprising:
providing an additional nonmagnetic spacer layer, the free layer being between the additional nonmagnetic spacer layer and the nonmagnetic spacer layer; and
providing an additional pinned layer, the additional nonmagnetic spacer layer being between the additional pinned layer and the free layer.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Tang Xueti
• Krounbi Mohamad Towfik
• Erickson Dustin
• Lee Donkoun
• Feng Gen

Classifications

• H01L27/226

  Electricity · mapped topic

• G11C11/161 Primary

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

• H01L43/10 Primary

  Electricity · mapped topic

• G11C11/165

  Auxiliary circuits · CPC title

• H01L43/12

  Electricity · mapped topic