Multilayered magnetic free layer structure containing an ordered magnetic alloy first magnetic free layer for spin-transfer torque (STT) MRAM

Patent metadata

Field	Value
Publication number	US-11557628-B2
Application number	US-202017135219-A
Country	US
Kind code	B2
Filing date	Dec 28, 2020
Priority date	Feb 4, 2019
Publication date	Jan 17, 2023
Grant date	Jan 17, 2023

Abstract

A multilayered magnetic free layer structure is provided that includes a first magnetic free layer and a second magnetic free layer separated by a non-magnetic layer in which the first magnetic free layer is composed of an ordered magnetic alloy. The ordered magnetic alloy provides a first magnetic free layer that has low moment, but is strongly magnetic. The use of such an ordered magnetic alloy first magnetic free layer in a multilayered magnetic free layer structure substantially reduces the switching current needed to reorient the magnetization of the two magnetic free layers.

First claim

What is claimed is:

1. A magnetic tunnel junction pillar comprising:
a multilayered magnetic free layer structure comprising a first magnetic free layer and a second magnetic free layer separated by a non-magnetic layer, wherein the first magnetic free layer has a magnetic moment from 100 emu/cm 3 to 500 emu/cm 3 and a perpendicular magnetic anisotropy from 2 kOe to 20 kOe and is composed of ordered magnetic alloy, and the second magnetic free layer has a perpendicular magnetic anisotropy from 1 kOe to 5 kOe and is composed of at least one magnetic material that differs from the ordered magnetic alloy;
a tunnel barrier layer located on a surface of the first magnetic free layer opposite a surface of the first magnetic free layer that forms an interface with the non-magnetic layer; and
a magnetic reference layer located on a surface of the tunnel barrier layer that is opposite the surface of the tunnel barrier that is located on the first magnetic free layer.

2. The magnetic tunnel junction pillar of claim 1 , wherein the ordered magnetic alloy is a Heusler alloy.

3. The magnetic tunnel junction pillar of claim 2 , wherein the Heusler alloy comprises Mn 3 Ge, Mn 3 Ga, Co 2 MnSi, Mn 3 Sn or Mn 3 Sb.

4. The magnetic tunnel junction pillar of claim 1 , wherein the ordered magnetic alloy is a L10 alloy.

5. The magnetic tunnel junction pillar of claim 4 , wherein the L10 alloy comprises MnAl or CoFe.

6. The magnetic tunnel junction pillar of claim 1 , further comprising an interfacial first magnetic free layer composed of CoFe alloy located between the first magnetic free layer and the tunnel barrier layer.

7. The magnetic tunnel junction pillar of claim 1 , wherein the non-magnetic layer is composed of a non-magnetic material that contains at least one element with an atomic number less than 74.

8. The magnetic tunnel junction pillar of claim 1 , wherein the non-magnetic layer has a thickness that allows the first and second magnetic free layers to couple together magnetically so that in equilibrium the first and second magnetic free layers are always parallel.

9. A memory device comprising:
a magnetic tunnel junction pillar located between a bottom electrode and a top electrode, the magnetic tunnel junction pillar comprising a multilayered magnetic free layer structure comprising a first magnetic free layer and a second magnetic free layer separated by a non-magnetic layer, wherein the first magnetic free layer has a magnetic moment from 100 emu/cm 3 to 500 emu/cm 3 and a perpendicular magnetic anisotropy from 2 kOe to 20 kOe and is composed of ordered magnetic alloy, and the second magnetic free layer has a perpendicular magnetic anisotropy from 1 kOe to 5 kOe and is composed of at least one magnetic material that differs from the ordered magnetic alloy, a tunnel barrier layer located on a surface of the first magnetic free layer opposite a surface of the first magnetic free layer that forms an interface with the non-magnetic layer, and a magnetic reference layer located on a surface of the tunnel barrier layer that is opposite the surface of the tunnel barrier that is located on the first magnetic free layer.

10. The memory device of claim 9 , wherein the ordered magnetic alloy is a Heusler alloy.

11. The memory device of claim 10 , wherein the Heusler alloy comprises Mn 3 Ge, Mn 3 Ga, Co 2 MnSi, Mn 3 Sn or Mn 3 Sb.

12. The memory device of claim 9 , wherein the ordered magnetic alloy is a L10 alloy.

13. The memory device of claim 12 , wherein the L10 alloy comprises MnAl or CoFe.

14. The memory device of claim 9 , further comprising an interfacial first magnetic free layer composed of CoFe alloy located between the first magnetic free layer and the tunnel barrier layer.

15. The memory device of claim 9 , wherein the non-magnetic layer is composed of a non-magnetic material that contains at least one element with an atomic number less than 74.

16. The memory device of claim 9 , wherein the non-magnetic layer has a thickness that allows the first and second magnetic free layers to couple together magnetically so that in equilibrium the first and second magnetic free layers are always parallel.

17. The memory device of claim 9 , wherein the memory device is a spin-transfer torque magnetic random access memory.

18. A method of improving the performance of spin-transfer torque magnetic random access memory, the method comprising:
providing a multilayered magnetic free layer structure on a surface of a tunnel barrier layer that is located on a magnetic reference layer, wherein the multilayered magnetic free layer structure comprises a first magnetic free layer and a second magnetic free layer separated by a non-magnetic layer, wherein the first magnetic free layer is located on the tunnel barrier layer and has a magnetic moment from 100 emu/cm 3 to 500 emu/cm 3 and a perpendicular magnetic anisotropy from 2 kOe to 20 kOe and is composed of ordered magnetic alloy, and the second magnetic has a perpendicular magnetic anisotropy from 1 kOe to 5 kOe and is composed of at least one magnetic material that differs from the ordered magnetic alloy.

19. The method of claim 18 , wherein the ordered magnetic alloy is a Heusler alloy or a L10 alloy.

20. The method of claim 18 , further comprising forming an interfacial first magnetic free layer composed of CoFe alloy between the first magnetic free layer and the tunnel barrier layer.

Assignees

• IBM

Inventors

• Worledge Daniel
• Hu Guohan

Classifications

• H01L27/222 Primary

  Electricity · mapped topic

• H01L43/10

  Electricity · mapped topic

• H01L43/12

  Electricity · mapped topic

• H01L43/08

  Electricity · mapped topic

• H10N50/85

  Materials of the active region · CPC title