Three axis magnetic field sensor

Patent metadata

Field	Value
Publication number	US-RE49404-E
Application number	US-201715470997-A
Country	US
Kind code	E1
Filing date	Mar 28, 2017
Priority date	Sep 25, 2009
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

Three bridge circuits (101, 111, 121), each include magnetoresistive sensors coupled as a Wheatstone bridge (100) to sense a magnetic field (160) in three orthogonal directions (110, 120, 130) that are set with a single pinning material deposition and bulk wafer setting procedure. One of the three bridge circuits (121) includes a first magnetoresistive sensor (141) comprising a first sensing element (122) disposed on a pinned layer (126), the first sensing element (122) having first and second edges and first and second sides, and a first flux guide (132) disposed non-parallel to the first side of the substrate and having an end that is proximate to the first edge and on the first side of the first sensing element (122). An optional second flux guide (136) may be disposed non-parallel to the first side of the substrate and having an end that is proximate to the second edge and the second side of the first sensing element (122).

First claim

The invention claimed is:

1. A ferromagnetic thin-film based magnetic field sensor comprising:
a substrate having a planar surface; and a first magnetoresistive sensor comprising:
a first sensing element having a first side lying parallel to the planar surface of the substrate, the first sensing element having a second side opposed to the first side and having first and second opposed edges; and
a first flux guide comprising a soft ferromagnetic material disposed non-parallel to the first side of the first sensing element and having an end that is proximate to the first edge and the first side of the first sensing element.

2. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein the first magnetoresistive sensor further comprises:
a second flux guide comprising a soft ferromagnetic material disposed non-parallel to the first side of the first sensing element and having an end that is proximate to the second edge and the second side of the first sensing element.

3. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein the first magnetoresistive sensor comprises one of an array of ferromagnetic thin-film based magnetic field sensors.

4. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein the first flux guide comprises a high aspect ratio structure non-parallel to the first sense element.

5. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein the first flux guide comprises a U shaped element.

6. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein the first flux guide includes a flared end.

7. The ferromagnetic thin-film based magnetic field sensor of claim 1 further comprising a material disposed adjacent the first flux guide and comprising one of the group consisting of a high conductivity metal and a dielectric material.

8. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein the first flux guide comprises a box shaped structure.

9. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein at least one of the first and second flux guides is disposed substantially orthogonal to the plane of the substrate.

10. The ferromagnetic thin-film based magnetic field sensor of claim 1 wherein at least one of the first and second flux guides is disposed at an angle of between 45 degrees and 90 degrees to the plane of the substrate.

11. The ferromagnetic thin-film based magnetic field sensor of claim 1 further comprising:
a second magnetoresistive sensor having a second sensing element for detecting a magnetic field in a second direction orthogonal to the first direction; and
a third magnetoresistive sensor having a third sensing element orthogonal to the second sensing element for detecting a magnetic field in a third direction orthogonal to the first and second directions,
wherein the third sensing element is in a plane with the first and second sensing elements.

12. The ferromagnetic thin-film based magnetic field sensor of claim 11 , wherein the first, second, and third sensor elements each comprise an imbalanced synthetic antiferromagnet formed with first and second ferromagnetic layers separated by a spacer layer, where the first and second ferromagnetic layers have different magnetic moments.

13. The ferromagnetic thin-film based magnetic field sensor of claim 1 further comprising:
the first magnetoresistive sensor comprising:
a first pinned layer;

a second magnetoresistive sensor comprising:
a second pinned layer; and
a second sensing element formed on the second pinned layer;

a third magnetoresistive sensor comprising:
a third pinned layer; and
a third sensing element formed on the third pinned layer and orthogonal to the second sensing element;
wherein the second and third pinned layers are oriented about 45 degrees to the first pinned layer.

14. The ferromagnetic thin-film based magnetic field sensor of claim 13 wherein the first magnetic tunnel junction further comprises:
a second flux guide disposed non-parallel to the first side of the first sensing element and having an end that is proximate to the second edge and the second side of the first sensing element.

15. The ferromagnetic thin-film based magnetic field sensor of claim 14 wherein the first and second flux guides each comprise an aspect ratio greater than 10.

16. A ferromagnetic thin-film magnetic field sensor comprising:
a first bridge circuit comprising first, second, third, and fourth magnetic tunnel junction sensors coupled as a Wheatstone bridge for sensing a magnetic field orthogonal to the plane of the sensors; the first magnetic tunnel junction sensor comprising:
a first reference layer; and
a first sensing element formed on the first reference layer, the first sensing element having first and second edges and first and second sides; and
a first flux guide comprising a soft ferromagnetic material disposed orthogonal to and spaced from the first edge and the first side of the first sensing element;
the second magnetic tunnel junction sensor comprising:
a second reference layer; and
a second sensing element formed on the second reference layer, the second sensing element having first and second edges and first and second sides; and
a second flux guide comprising a soft ferromagnetic material disposed orthogonal to and spaced from the first edge and the first side of the second sensing element;
the third magnetic tunnel junction sensor comprising:
a third reference layer; and
a third sensing element formed on the third reference layer, the third sensing element having first and second edges and first and second sides; and
a third flux guide comprising a soft ferromagnetic material disposed orthogonal to and spaced from the first edge and the first side of the third sensing element;
the fourth magnetic tunnel junction sensor comprising:
a fourth reference layer; and
a fourth sensing element formed on the fourth reference layer, the fourth sensing element having first and second edges and first and second sides; and
a fourth flux guide disposed orthogonal to and spaced from the first edge and the first side of the fourth sensing element.

17. The ferromagnetic thin-film based magnetic field sensor of claim 16 wherein the first, second, third, and fourth magnetic tunnel junction sensors further comprise fifth, sixth, seventh, and eighth flux guides disposed orthogonal to and spaced from the second edge and the second side of the first, second, third, and fourth sensing elements, respectively.

18. The ferromagnetic thin-film based magnetic field sensor of claim 16 further comprising:
a second bridge circuit comprising fifth, sixth, seventh, and eighth magnetic tunnel junction sensors coupled as a second Wheatstone bridge for sensing a magnetic field in a second direction orthogonal to the first direction; and
a third bridge circuit comprising, ninth, tenth, eleventh, and twelfth magnetic tunnel junction sensors coupled as a third Wheatstone bridge for sensing a magnetic field in a third direction orthogonal to the first and second directions.

19. The ferromagnetic thin-film based magnetic field sensor of claim 16 wherein each of the first, second, third, and fourth sensors comprises an array of sense elements.

20. A method of testing the functionality and sensitivity of a response of the Z axis of a ferromagnetic thin-film magnetic field sensor including a substrate having a planar surface, and a first magnetoresistive sensor comprising

Assignees

• Everspin Technologies Inc

Inventors

• Mather Phillip
• Slaughter Jon
• Rizzo Nicholas

Classifications

• H01L27/22 Primary

  Electricity · mapped topic

• G01R33/093 Primary

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• H01L43/08

  Electricity · mapped topic

• B82Y25/00 Primary

  Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance · CPC title

• H10N59/00

  Integrated devices, or assemblies of multiple devices, comprising at least one galvanomagnetic or Hall-effect element covered by groups H10N50/00 - H10N52/00 (MRAM devices H10B61/00) · CPC title