Minimal thickness synthetic antiferromagnetic (SAF) structure with perpendicular magnetic anisotropy for STT-MRAM

Patent metadata

Field	Value
Publication number	US-10868235-B2
Application number	US-201916258770-A
Country	US
Kind code	B2
Filing date	Jan 28, 2019
Priority date	Sep 11, 2012
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

A synthetic antiferromagnetic structure for a spintronic device is disclosed and has an FL2/Co or Co alloy/antiferromagnetic coupling/Co or Co alloy/CoFeB configuration where FL2 is a ferromagnetic free layer with intrinsic PMA. Antiferromagnetic coupling is improved by inserting a Co or Co alloy dusting layer on top and bottom surfaces of the antiferromagnetic coupling layer. The FL2 layer may be a L10 ordered alloy, a rare earth-transition metal alloy, or an (A1/A2)n laminate where A1 is one of Co, CoFe, or an alloy thereof, and A2 is one of Pt, Pd, Rh, Ru, Ir, Mg, Mo, Os, Si, V, Ni, NiCo, and NiFe, or A1 is Fe and A2 is V. A method is also provided for forming the synthetic antiferromagnetic structure.

First claim

We claim:

1. A synthetic antiferromagnetic structure, comprising:
a FL2 layer with intrinsic perpendicular magnetic anisotropy wherein a magnetization direction thereof is perpendicular-to-plane of the FL2 layer;
a CoFeB layer with perpendicular magnetic anisotropy in which a magnetization direction in said CoFeB layer is perpendicular-to-plane of the CoFeB layer and is established by antiferromagnetic coupling with the FL2 layer through an antiferromagnetic coupling layer formed between the FL2 layer and CoFeB layer;
the antiferromagnetic coupling layer that is made of a non-magnetic material;
a first Co or Co alloy dusting layer formed between the antiferromagnetic coupling layer and the FL2 layer, and a second Co or Co alloy dusting layer formed between the antiferromagnetic coupling layer and CoFeB layer; and
a seed layer interfacing with a bottom electrode, the seed layer including Ta, Mg, Ni and Cr.

2. The synthetic antiferromagnetic structure of claim 1 wherein the FL2 layer is comprised of an (A1/A2) n laminate where n is an integer less than 6, A1 is one of Co, CoFe, or an alloy thereof, and A2 is one of Pt, Pd, Rh, Ru, Ir, Mg, Mo, Os, Si, V, Ni, NiCo, and NiFe, or A1 is Fe and A2 is V.

3. The synthetic antiferromagnetic structure of claim 1 wherein the FL2 layer is a L10 ordered alloy of the form MT wherein M is Rh, Pd, Pt, Ir, or an alloy thereof, and T is Fe, Co, Ni or alloy thereof, or the FL2 layer is made of a rare earth-transition metal alloy that is TbCo, TbFeCo, or GdFeCo.

4. The synthetic antiferromagnetic structure of claim 1 wherein the FL2 layer is comprised of a (A1/A2) n laminate where n is a lamination number, A1 is one of Co, CoFe, or an alloy thereof, A2 is one of Rh, Ir, Ru, Os, Mo, or an alloy thereof and A2 provides ferromagnetic or antiferromagnetic coupling between neighboring A1 layers when n is between 2 and 10.

5. The synthetic antiferromagnetic structure of claim 1 wherein the antiferromagnetic coupling layer is Ru, Ir, Rh, Os, Mo, V, or an alloy thereof.

6. The synthetic antiferromagnetic structure of claim 1 , wherein the FL2 layer has a composition selected from a first composition and a second compositions,
wherein the first composition of the FL2 layer is an (A1/A2) n laminate where n is an integer less than 6, A1 is one of Co, CoFe, or an alloy thereof, and A2 is one of Mg, Si, V, NiCo, and NiFe, or A1 is Fe and A2 is V, and
wherein the second composition of the FL2 layer is a rare earth-transition metal alloy selected from the consisting of TbCo, TbFeCo and GdFeCo.

7. A synthetic antiferromagnetic structure comprising:
an AP2 reference layer with intrinsic perpendicular magnetic anisotropy wherein a magnetization direction thereof is perpendicular-to-plane of the AP2 reference layer;
a first CoFeB layer with perpendicular magnetic anisotropy in which a magnetization direction in the first CoFeB layer is perpendicular-to-plane of the first CoFeB layer;
a first antiferromagnetic coupling layer including a first non-magnetic material disposed between the AP2 reference layer and the first CoFeB layer;
a first dusting layer formed between the first antiferromagnetic coupling layer and the AP2 reference layer;
a second dusting layer formed between the first antiferromagnetic coupling layer and the first CoFeB layer; and
a seed layer interfacing with the AP2 reference layer, the seed layer including Ta, Mg, Ni and Cr.

8. The synthetic antiferromagnetic structure of claim 7 , wherein at least one of the first and second dusting layers includes Co.

9. The synthetic antiferromagnetic structure of claim 7 , further comprising:
a free layer with intrinsic perpendicular magnetic anisotropy wherein a magnetization direction thereof is perpendicular-to-plane of the free layer;
a second antiferromagnetic coupling layer including a second non-magnetic material; and
a second CoFeB layer with perpendicular magnetic anisotropy in which a magnetization direction in the second CoFeB layer is perpendicular-to-plane of the second CoFeB layer.

10. The synthetic antiferromagnetic structure of claim 9 , further comprising:
a third dusting layer formed between the second antiferromagnetic coupling layer and the free layer; and
a fourth dusting layer formed between the second antiferromagnetic coupling layer and the second CoFeB layer.

11. The synthetic antiferromagnetic structure of claim 9 , further comprising a tunnel barrier layer extending from the first CoFeB layer to the second CoFeB layer.

12. The synthetic antiferromagnetic structure of claim 7 , wherein the AP2 reference layer is comprised of an (A1/A2) n laminate where n is an integer less than 6, A1 is one of Co, CoFe, or an alloy thereof, and A2 is one of Pt, Pd, Rh, Ru, Ir, Mg, Mo, Os, Si, V, Ni, NiCo, and NiFe.

13. The synthetic antiferromagnetic structure of claim 7 , wherein the first antiferromagnetic coupling layer includes a material selected from the group consisting of Ru, 1 r , Rh, Os, Mo, V, and an alloy thereof.

14. A synthetic antiferromagnetic structure, comprising:
a synthetic antiferromagnetic structure including:
a FL2 layer with intrinsic perpendicular magnetic anisotropy wherein a magnetization direction thereof is perpendicular-to-plane of the FL2 layer;
a first antiferromagnetic coupling layer including a first non-magnetic material; and
a first CoFeB layer with perpendicular magnetic anisotropy in which a magnetization direction in the first CoFeB layer is perpendicular-to-plane of the first CoFeB layer; and

a synthetic antiferromagnetic reference layer structure including:
an AP2 reference layer with intrinsic perpendicular magnetic anisotropy wherein a magnetization direction thereof is perpendicular-to-plane of the AP2 reference layer;
a second antiferromagnetic coupling layer including a second non-magnetic material; and
a second CoFeB layer with perpendicular magnetic anisotropy in which a magnetization direction in the second CoFeB layer is perpendicular-to-plane of the second CoFeB layer; and

a seed layer interfacing with the AP2 reference layer, the seed layer including Ta, Mg, Ni and Cr.

15. The synthetic antiferromagnetic structure of claim 14 , further comprising:
a first dusting layer disposed between the first antiferromagnetic coupling layer and the FL2 layer, the first dusting layer formed of a material selected from the group consisting of Co and Co alloy;
a second dusting layer disposed between the first antiferromagnetic coupling layer and first CoFeB layer, the second dusting layer formed of a material selected from the group consisting of Co and Co alloy.

16. The synthetic antiferromagnetic structure of claim 15 further comprising:
a third dusting layer disposed between the second antiferromagnetic coupling layer and the AP2 reference layer, the third dusting layer formed of a material selected from the group consisting of Co and Co alloy; and
a fourth dusting layer disposed between the second antiferromagnetic coupling layer and second CoFeB layer, the fourth dusting layer formed of a material selected from the group consisting of Co and Co alloy.

17. The synthetic antiferromagnetic structure of claim 14 , further comprising a tunnel barrier layer extending from the first CoFeB layer to the second CoFeB layer.

18. The synthetic antiferromagnetic structure of claim 14 further comprising a capping layer physically contacting a top surface of the FL2 layer.

19. The synthetic antiferromagnetic structure of claim 14 , wherein the second antiferromagnetic coupling layer

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Beach Robert
• Jan Guenole
• Wang Yu-Jen
• Tong Ru-Ying

Classifications

• H01F10/3272 Primary

  by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets · CPC title

• H10D48/40

  Devices controlled by magnetic fields · CPC title

• H10N50/85

  Materials of the active region · CPC title

• H01F10/3286

  Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy · CPC title

• G11C11/161

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