Magnetic field sensor

Patent metadata

Field	Value
Publication number	US-9640753-B2
Application number	US-201414168095-A
Country	US
Kind code	B2
Filing date	Jan 30, 2014
Priority date	Aug 30, 2010
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A sensor and fabrication process are provided for forming reference layers with substantially orthogonal magnetization directions having zero offset with a small compensation angle. An exemplary embodiment includes a sensor layer stack of a magnetoresistive thin-film based magnetic field sensor, the sensor layer stack comprising a pinning layer; a pinned layer including a layer of amorphous material over the pinning layer, and a first layer of crystalline material over the layer of amorphous material; a nonmagnetic coupling layer over the pinned layer; a fixed layer over the nonmagnetic coupling layer; a tunnel barrier over the fixed layer; and a sense layer over the nonmagnetic intermediate layer. Another embodiment includes a sensor layer stack where a pinned layer including two crystalline layers separated by a amorphous layer.

First claim

What is claimed is:

1. A magnetoresistive thin-film magnetic field sensor, comprising:
a pinning layer;
a pinned layer comprising:
an amorphous ferromagnetic layer disposed on or adjacent the pinning layer; and
a first crystalline ferromagnetic layer disposed on or adjacent the amorphous ferromagnetic layer;

a nonmagnetic coupling layer disposed on or adjacent the pinned layer;
a ferromagnetic fixed layer disposed on or adjacent the nonmagnetic coupling layer;
a dielectric tunnel barrier layer disposed on or adjacent the ferromagnetic fixed layer; and
a ferromagnetic sense layer disposed on or adjacent the dielectric tunnel barrier layer.

2. The magnetoresistive thin-film magnetic field sensor of claim 1 , wherein the pinned layer further includes:
a second crystalline ferromagnetic layer disposed between the amorphous ferromagnetic layer and the pinning layer.

3. The magnetoresistive thin-film magnetic field sensor of claim 2 , wherein the second crystalline ferromagnetic layer comprises cobalt and iron.

4. The magnetoresistive thin-film magnetic field sensor of claim 1 , wherein the first crystalline ferromagnetic layer comprises (i) cobalt and iron or (ii) cobalt, iron, and boron.

5. The magnetoresistive thin-film magnetic field sensor of claim 1 , wherein the ferromagnetic sense layer comprises nickel and iron, and wherein the first crystalline ferromagnetic layer comprises (i) cobalt and iron or (ii) cobalt, iron, and boron.

6. The magnetoresistive thin-film magnetic field sensor of claim 1 , wherein the amorphous ferromagnetic layer comprises cobalt, iron, and boron, and wherein the amorphous ferromagnetic layer includes a thickness in the range of 2 to 15 Angstroms.

7. The magnetoresistive thin-film magnetic field sensor of claim 1 , wherein the pinned layer and the ferromagnetic fixed layer have different magnetic moments.

8. The magnetoresistive thin-film magnetic field sensor of claim 1 , wherein the ferromagnetic fixed layer has a magnetization that is aligned along a short axis.

9. The magnetoresistive thin-film magnetic field sensor of claim 1 , further comprising:
a diffusion barrier layer disposed on or adjacent the ferromagnetic sense layer.

10. A magnetoresistive thin-film magnetic field sensor, comprising:
a pinning layer;
a pinned layer comprising:
a first layer including cobalt and iron, wherein the first layer is disposed on or adjacent the pinning layer;
a second layer including cobalt and iron, wherein the second layer is disposed on or adjacent the first layer; and
a third layer including cobalt and iron, wherein the third layer is disposed on or adjacent the second layer;

a nonmagnetic coupling layer disposed on or adjacent the pinned layer;
a ferromagnetic fixed layer disposed on or adjacent the nonmagnetic coupling layer;
a dielectric tunnel barrier layer disposed on or adjacent the ferromagnetic fixed layer; and
a ferromagnetic sense layer disposed on or adjacent the dielectric tunnel barrier layer.

11. The magnetoresistive thin-film magnetic field sensor of claim 10 , wherein the second layer further includes boron.

12. The magnetoresistive thin-film magnetic field sensor of claim 10 , wherein the ferromagnetic sense layer comprises nickel and iron.

13. The magnetoresistive thin-film magnetic field sensor of claim 10 , wherein the second layer includes a thickness in the range of 2 to 15 Angstroms.

14. The magnetoresistive thin-film magnetic field sensor of claim 10 , wherein the pinned layer and the ferromagnetic fixed layer have different magnetic moments.

15. The magnetoresistive thin-film magnetic field sensor of claim 10 , wherein the pinning layer includes platinum or manganese.

16. The magnetoresistive thin-film magnetic field sensor of claim 10 , wherein the ferromagnetic fixed layer has a magnetization that is aligned along a short axis.

17. The magnetoresistive thin-film magnetic field sensor of claim 10 , further comprising:
a diffusion barrier layer disposed on or adjacent the ferromagnetic sense layer, wherein the diffusion barrier layer includes aluminum.

18. A magnetoresistive thin-film magnetic field sensor, comprising:
a pinning layer comprising platinum and manganese;
a pinned layer disposed on or adjacent the pinning layer, wherein the pinned layer comprises:
a first layer comprising cobalt and iron; and
a second layer comprising cobalt and iron;

a coupling layer comprising ruthenium disposed on or adjacent the pinned layer;
a ferromagnetic fixed layer disposed on or adjacent the coupling layer;
a dielectric layer disposed on or adjacent the ferromagnetic fixed layer; and
a free layer disposed on or adjacent the dielectric layer, wherein the free layer comprises nickel, iron, or an alloy thereof.

19. The magnetoresistive thin-film magnetic field sensor of claim 18 , further comprising:
a diffusion barrier layer disposed on or adjacent the free layer, wherein the diffusion barrier layer comprises aluminum.

20. The magnetoresistive thin-film magnetic field sensor of claim 18 , further comprising:
a diffusion barrier layer disposed on or adjacent the free layer; and
a capping layer disposed on or adjacent the diffusion barrier layer.

21. The magnetoresistive thin-film magnetic field sensor of claim 18 , wherein at least one of the first and second layers of the pinned layer includes boron.

22. The magnetoresistive thin-film magnetic field sensor of claim 18 , further comprising an intermediate layer in between the first and second layers of the pinned layer.

23. The magnetoresistive thin-film magnetic field sensor of claim 18 , further comprising an intermediate layer in between the first and second layers of the pinned layer, wherein the intermediate layer includes boron.

Assignees

• Everspin Technologies Inc

Inventors

• Sun Jijun
• Mather Phillip
• Pietambaram Srinivas
• Slaughter Jon
• Whig Renu
• Rizzo Nicholas

Classifications

• G01R33/098

  comprising tunnel junctions, e.g. tunnel magnetoresistance sensors · CPC title

• H01L43/12

  Electricity · mapped topic

• Y10T29/49117

  Conductor or circuit manufacturing · CPC title

• H01L43/10 Primary

  Electricity · mapped topic

• H10N50/85 Primary

  Materials of the active region · CPC title