Perpendicular magnetic memory element having magnesium oxide cap layer

Patent metadata

Field	Value
Publication number	US-9748471-B2
Application number	US-201715440948-A
Country	US
Kind code	B2
Filing date	Feb 23, 2017
Priority date	Dec 10, 2010
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

The present invention is directed to an STT-MRAM device comprising a plurality of memory elements. Each of the memory elements includes an MTJ structure that comprises a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween; a first perpendicular enhancement layer (PEL) formed adjacent to the magnetic free layer structure; a magnetic dead layer formed adjacent to the first PEL; and a magnetic fixed layer exchange coupled to the magnetic reference layer structure through an anti-ferromagnetic coupling layer. The magnetic reference layer structure includes a first magnetic reference layer formed adjacent to the insulating tunnel junction layer and a second magnetic reference layer separated from the first magnetic reference layer by a second PEL. The first and second magnetic reference layers have a first invariable magnetization direction substantially perpendicular to layer planes thereof.

First claim

What is claimed is:

1. A spin transfer torque magnetic random access memory (STT-MRAM) device comprising a plurality of memory elements, each of said memory elements including a magnetic tunnel junction (MTJ) structure, said MTJ structure comprising:
a magnetic free layer and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween;
a magnetic fixed layer exchange coupled to said magnetic reference layer structure through an anti-ferromagnetic coupling layer;
a first perpendicular enhancement layer (PEL) formed adjacent to said magnetic free layer opposite said insulating tunnel junction layer; and
a magnetic dead layer formed adjacent to said first PEL opposite said magnetic free layer,
wherein said magnetic reference layer structure includes a first magnetic reference layer formed adjacent to said insulating tunnel junction layer and a second magnetic reference layer separated from said first magnetic reference layer by a second PEL, said first and second magnetic reference layers having a first invariable magnetization direction substantially perpendicular to layer planes thereof, said magnetic fixed layer has a second invariable magnetization direction that is substantially perpendicular to a layer plane thereof and is opposite to said first invariable magnetization direction, said magnetic free layer has a variable magnetization direction substantially perpendicular to a layer plane thereof.

2. The STT-MRAM device according to claim 1 , wherein said magnetic free layer comprises cobalt, iron, and boron.

3. The STT-MRAM device according to claim 1 , wherein said first PEL is made of magnesium oxide.

4. The STT-MRAM device according to claim 1 , wherein said magnetic dead layer comprises cobalt and iron.

5. The STT-MRAM device according to claim 1 , wherein said magnetic dead layer comprises cobalt, iron, and boron.

6. The STT-MRAM device according to claim 1 , wherein said magnetic dead layer has a thickness less than about 0.7 nm.

7. The STT-MRAM device according to claim 1 , wherein said second PEL is made of tungsten, molybdenum, tantalum, hafnium, zirconium, niobium, or any combination thereof.

8. The STT-MRAM device according to claim 1 , wherein said first magnetic reference layer comprises cobalt, iron, and boron.

9. A spin transfer torque magnetic random access memory (STT-MRAM) device comprising a plurality of memory elements, each of said memory elements including a magnetic tunnel junction (MTJ) structure, said MTJ structure comprising:
a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween;
a magnetic fixed layer exchange coupled to said magnetic reference layer structure through an anti-ferromagnetic coupling layer;
a magnesium oxide layer formed adjacent to said magnetic free layer structure opposite said insulating tunnel junction layer; and
a metal layer comprising cobalt and iron formed adjacent to said magnesium oxide layer opposite said magnetic free layer structure,
wherein said magnetic reference layer structure includes a first magnetic reference layer formed adjacent to said insulating tunnel junction layer and a second magnetic reference layer separated from said first magnetic reference layer by a first perpendicular enhancement layer (PEL), said first and second magnetic reference layers having a first invariable magnetization direction substantially perpendicular to layer planes thereof, said magnetic fixed layer has a second invariable magnetization direction that is substantially perpendicular to a layer plane thereof and is opposite to said first invariable magnetization direction, said magnetic free layer structure includes one or more magnetic free layers having a variable magnetization direction substantially perpendicular to layer planes thereof.

10. The STT-MRAM device according to claim 9 , wherein said magnetic free layer structure includes a magnetic free layer that comprises cobalt, iron, and boron.

11. The STT-MRAM device according to claim 9 , wherein said metal layer further comprises boron.

12. The STT-MRAM device according to claim 9 , wherein said metal layer has a thickness less than about 0.7 nm.

13. The STT-MRAM device according to claim 9 , wherein said metal layer is non-magnetic.

14. The STT-MRAM device according to claim 9 , wherein said magnetic free layer structure includes a first magnetic free layer formed adjacent to said insulating tunnel junction layer and a second magnetic free layer separated from said first magnetic free layer by a second PEL, said first and said second magnetic free layers having respectively a first and a second variable magnetization directions that are substantially perpendicular to layer planes thereof and are parallel to each other.

15. The STT-MRAM device according to claim 14 , wherein said first magnetic free layer comprise cobalt, iron, and boron.

16. The STT-MRAM device according to claim 14 , wherein said second PEL is made of tungsten, molybdenum, tantalum, hafnium, zirconium, niobium, or any combination thereof.

17. The STT-MRAM device according to claim 9 , wherein said first magnetic reference layer comprises cobalt, iron, and boron.

18. The STT-MRAM device according to claim 9 , wherein said magnetic fixed layer has a multilayer structure formed by interleaving one or more layers of a first material with one or more layers of a second material, at least one of said first and second materials being magnetic.

19. The STT-MRAM device according to claim 18 , wherein said first material is cobalt or a material comprising cobalt and iron.

20. The STT-MRAM device according to claim 18 , wherein said second material is nickel, or platinum, or palladium.

Assignees

• Avalanche Technology Inc

Inventors

• Zhou Yuchen
• Wang Zihui
• Gan Huadong
• Huai Yiming

Classifications

• H01L43/10

  Electricity · mapped topic

• H01F10/14

  containing iron or nickel ({H01F10/126} , H01F10/13, H01F10/16 take precedence) · CPC title

• H01F10/3222

  Exchange coupled hard/soft multilayers, e.g. CoPt/Co or NiFe/CoSm (nanocomposite spring magnets H01F1/0579) · CPC title

• H01F10/16

  containing cobalt ({H01F10/126} , H01F10/13 take precedence) · CPC title

• H01L27/228

  Electricity · mapped topic