MAGNETIC RANDOM ACCESS MEMORY HAVING PERPENDICULAR ENHANCEMENT LAYER

• US 20150270311A1
• Filed: 06/03/2015
• Published: 09/24/2015
• Est. Priority Date: 12/10/2010
• Status: Active Grant

• Current Assignee: Avalanche Technology Incorporated
• Original Assignee: Avalanche Technology Incorporated
• Inventors: Gan, Huadong, Huai, Yiming, Zhou, Yuchen, Wang, Zihui, Wang, Xiaobin, Yen, Bing K.
• Granted Patent: US 9,559,144 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H01F 10/3286 Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy
• CPC Class Codes: H01F 10/329 Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32
• CPC Class Codes: H01L 23/528 Geometry or layout of the interconnection structure H01L27/0207 takes precedence; algorithms G06F30/00
• CPC Class Codes: H01L 29/66984 Devices using spin polarized carriers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

The present invention is directed to a spin transfer torque (STT) MRAM device having a perpendicular magnetic tunnel junction (MTJ) memory element. The memory element includes a perpendicular MTJ structure in between a non-magnetic seed layer and a non-magnetic cap layer. The MTJ structure comprises a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween, an anti-ferromagnetic coupling layer formed adjacent to the magnetic reference layer structure, and a magnetic fixed layer formed adjacent to the anti-ferromagnetic coupling layer. At least one of the magnetic free and reference layer structures includes a non-magnetic perpendicular enhancement layer, which improves the perpendicular anisotropy of magnetic layers adjacent thereto.

Claims

1. A magnetic random access memory device comprising a plurality of memory elements, each of said memory elements including a magnetic tunnel junction (MTJ) structure in between a non-magnetic seed layer and a non-magnetic cap layer, said MTJ structure comprising a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween, 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 non-magnetic perpendicular enhancement layer with said first and second magnetic reference layers having a first fixed magnetization direction substantially perpendicular to layer planes thereof, said magnetic free layer structure includes one or more magnetic free layers having a variable magnetization direction substantially perpendicular to layer planes thereof.

2. The magnetic random access memory device according to claim 1, further comprising:

a plurality of selection transistors, each of said selection transistors being coupled to a respective one of said memory elements to collectively form a memory cell;

a plurality of parallel word lines, each of said word lines being coupled to gates of a respective row of said selection transistors in a first direction; and

a plurality of parallel bit lines, each of said bit lines being coupled to a respective row of said memory elements in a second direction perpendicular to said first direction.

3. The magnetic random access memory device according to claim 1, wherein said magnetic free layer structure includes a magnetic layer comprising cobalt, iron, and boron.

4. The magnetic random access memory device according to claim 3, wherein said magnetic free layer structure further includes another magnetic free layer that comprises cobalt and iron.

5. The magnetic random access memory device according to claim 3, wherein said magnetic free layer structure further includes another magnetic free layer that comprises cobalt, iron, and tantalum.

6. The magnetic random access memory device according to claim 1, wherein said magnetic free layer structure includes two magnetic free layers separated by a second non-magnetic perpendicular enhancement layer, one of said two magnetic free layers being formed adjacent to said insulating tunnel junction layer and comprising cobalt, iron, and boron, the other one of said two magnetic free layers comprising cobalt and iron.

7. The magnetic random access memory device according to claim 6, wherein said second non-magnetic perpendicular enhancement layer includes a metallic layer made of tungsten, hafnium, tantalum, molybdenum, zirconium, niobium, or any combination thereof.

8. The magnetic random access memory device according to claim 1, wherein said non-magnetic cap layer includes an insulating layer that comprises magnesium and oxygen.

9. The magnetic random access memory device according to claim 1, wherein said first magnetic reference layer comprises cobalt, iron, and boron.

10. The magnetic random access memory device according to claim 1, wherein said first non-magnetic perpendicular enhancement layer includes a metallic layer made of tungsten, hafnium, tantalum, molybdenum, zirconium, niobium, or any combination thereof.

11. The magnetic random access memory device according to claim 1, wherein said second magnetic reference layer has a multilayer structure formed by interleaving layers of a first material with layers of a second material, at least one of said first and second materials being magnetic.

12. The magnetic random access memory device according to claim 11, wherein said first material is Co or CoFe, said second material is Pt, Pd, Ni, or any combination thereof.

13. The magnetic random access memory device according to claim 1, wherein said MTJ structure further comprises:

a tuning layer formed adjacent to said magnetic free layer structure; and

a magnetic compensation layer formed adjacent to said tuning layer, said magnetic compensation layer having a second fixed magnetization direction substantially opposite to said first fixed magnetization direction.

14. The magnetic random access memory device according to claim 13, wherein said tuning layer includes an insulating layer that comprises magnesium and oxygen.

15. The magnetic random access memory device according to claim 13, wherein said magnetic compensation layer has a multilayer structure formed by interleaving layers of a first material with layers of a second material, at least one of said first and second materials being magnetic.

16. The magnetic random access memory device according to claim 15, wherein said first material is Co or CoFe, said second material is Pt, Pd, Ni, or any combination thereof.

17. The magnetic random access memory device according to claim 1, wherein said MTJ structure further comprises:

an anti-ferromagnetic coupling layer formed adjacent to said second magnetic reference layer; and

a magnetic fixed layer formed adjacent to said anti-ferromagnetic coupling layer, said magnetic fixed layer having a second fixed magnetization direction substantially opposite to said first fixed magnetization direction.

18. The magnetic random access memory device according to claim 17, wherein said magnetic fixed layer has a multilayer structure formed by interleaving layers of a first material with layers of a second material, at least one of said first and second materials being magnetic.

19. The magnetic random access memory device according to claim 17, wherein said first material is Co or CoFe, said second material is Pt, Pd, Ni, or any combination thereof.

20. The magnetic random access memory device according to claim 19, wherein said non-magnetic seed layer is formed adjacent to said magnetic fixed layer and includes a metallic layer made of NiCr, NiTa, or NiTi.