Integrated magnetoresistive sensor, in particular three-axis magnetoresistive sensor and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-9442168-B2
Application number	US-201113996922-A
Country	US
Kind code	B2
Filing date	Dec 23, 2011
Priority date	Dec 23, 2010
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

An integrated magnetoresistive device, where a substrate of semiconductor material is covered, on a first surface, by an insulating layer. A magnetoresistor of ferromagnetic material extends in the insulating layer and defines a sensitivity plane of the sensor. A concentrator of ferromagnetic material including at least one arm, extending in a transversal direction to the sensitivity plane and vertically offset to the magnetoresistor. In this way, magnetic flux lines directed perpendicularly to the sensitivity plane are concentrated and deflected so as to generate magnetic-field components directed in a parallel direction to the sensitivity plane.

First claim

What is claimed is:

1. An integrated magnetoresistive device, comprising:
a substrate having first and second surfaces,
an insulating layer extending on the first surface,
a first magnetoresistor of a first ferromagnetic material extending in the insulating layer and having a sensitivity plane parallel to the first and second surfaces,
a second magnetoresistor of the first ferromagnetic material connected in series with the first magnetoresistor and extending in the insulating layer and having a sensitivity plane parallel to the first and second surfaces,
wherein each of the first and second magnetoresistors comprise:
a ferromagnetic material strip extending longitudinally parallel to a first axis parallel to the sensitivity plane, and
a plurality of conductive transversal strips overlaid to the respective ferromagnetic material strip, the conductive transversal strips extending transversally to the first axis, parallel to the sensitivity plane, and wherein the conductive transversal strips of the first and second magnetoresistors extend parallel to each other, and

a concentrator of a second ferromagnetic material including a first arm extending longitudinally parallel to the first axis and in a transversal direction to the sensitivity plane and vertically offset to the first and second magnetoresistors so that magnetic flux lines in the concentrator that are directed perpendicularly to the sensitivity plane are deflected into magnetic field components extending through the first and second magnetoresistors and directed in a parallel direction to the sensitivity plane, the first arm positioned between the first and second magnetoresistors.

2. An integrated magnetoresistive device according to claim 1 , wherein the substrate is a semiconductor substrate and the concentrator is formed in the substrate.

3. An integrated magnetoresistive device according to claim 1 , wherein the substrate is a semiconductor substrate and has a trench extending from the second surface toward the first surface and the first arm of the concentrator is adjacent to and covers a lateral wall of the trench.

4. An integrated magnetoresistive device according to claim 1 , wherein the substrate has a trench extending from the first surface toward the second surface and the first arm of the concentrator is adjacent to and covers a lateral wall of the trench.

5. An integrated magnetoresistive device according to claim 1 , comprising a ferromagnetic concentrator in the insulating material arranged offset with respect to the first magnetoresistor on an opposite side thereof with respect to the first arm.

6. An integrated magnetoresistive device according to claim 1 , wherein the concentrator is formed in a trench in a body bonded to the insulating layer with the trench facing the insulating layer.

7. An integrated magnetoresistive device according to claim 1 , wherein the concentrator is formed in a trench in the insulating layer.

8. An integrated magnetoresistive device according to claim 1 , wherein the concentrator includes a pair of distinct arms including the first arm, each longitudinally extending transversely to the sensitivity plane.

9. An integrated magnetoresistive device according to claim 1 , wherein the concentrator has a U shape in a cross-section, and comprises a pair of distinct arms, including the first arm, connected by a base portion substantially parallel to the first surface.

10. An integrated magnetoresistive device according to claim 1 , wherein the first arm of the concentrator has a thickness comprised between 0.5 and 10 μm and a length equal or greater than ten times the thickness, and the distance between the arm and the first magnetoresistor in a perpendicular direction to the sensitivity plane is smaller than 30 μm.

11. An integrated magnetoresistive device according to claim 1 , wherein the second ferromagnetic material is selected between a cobalt alloy and a Fe—Ni alloy.

12. An integrated magnetoresistive device according to claim 1 , comprising a second magnetoresistor extending in the insulating layer and coplanar to the first magnetoresistor, wherein the concentrator is equidistant from the first and the second magnetoresistors.

13. An integrated magnetoresistive device according to claim 1 , wherein the first and second magnetoresistors connected in series form a first branch of a first Wheatstone bridge including a second branch, the first and second branches mutually connected in parallel between a pair of input terminals and defining a pair of taps forming output terminals, wherein:
the magnetoresistors of the first branch are arranged symmetrically to magnetoresistors of the second branch with respect to a second axis parallel to the sensitivity plane and perpendicular to the first axis;
wherein the conductive transversal strips extend transversally to the first and to the second axes; and
wherein the ferromagnetic material strips are arranged symmetrically with respect to the concentrator.

14. An integrated magnetoresistive device according to claim 13 , comprising a second plurality of magnetoresistors connected to form a second Wheatstone bridge, wherein the magnetoresistors of the second plurality each include a ferromagnetic material strip, the ferromagnetic material strips of said magnetoresistors of said second plurality are arranged perpendicularly to the ferromagnetic material strips of the magnetoresistors forming the first Wheatstone bridge.

15. An integrated magnetoresistive device according to claim 13 , wherein the first Wheatstone bridge comprises a first and a second switches arranged respectively on the first and second branches and configured to, in a first operative condition, respectively connect one magnetoresistor in the first branch to the first output terminal and another magnetoresistor in the second branch to the second output terminal and, in a second operative condition, respectively connect said one magnetoresistor in the first branch to the second output terminal and said another magnetoresistor in the second branch to the first output terminal.

16. An integrated electronic compass, comprising a magnetoresistive device according to claim 13 , and an angle calculation unit, coupled to the magnetoresistive sensors and configured to calculate an angle of a component of magnetic field parallel to said sensitivity plane.

17. An integrated magnetoresistive device, comprising:
a plurality of magnetoresistors connected to form a Wheatstone bridge including a first and a second branch mutually connected in parallel between a pair of input terminals and defining a pair of taps forming output terminals;
the magnetoresistors extending in an insulating layer and having a sensitivity plane parallel to a surface of the insulating layer;
wherein the magnetoresistors of the first branch are arranged symmetrically to the magnetoresistors of the second branch with respect to a first axis parallel to the sensitivity plane;
wherein the magnetoresistors each comprise:
a ferromagnetic material strip extending longitudinally parallel to a second axis substantially perpendicular to the first axis and parallel to the sensitivity plane; and
a plurality of conductive transversal strips overlaid to the respective ferromagnetic material strip, the conductive transversal strips extending transversally to the first and to the second axes, parallel to the sensitivity plane; and

a concentrator of a ferromagnetic material including a first arm extending longitudinally in a transversal direction to the sensitivity plane and vertically offset to the magnetoresistors so

Assignees

• Paci Dario
• Morelli Marco
• Riva Caterina
• St Microelectronics Srl

Inventors

• Paci Dario
• Morelli Marco
• Riva Caterina

Classifications

• G01R33/093

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

• G01R33/0011 Primary

  comprising means, e.g. flux concentrators, flux guides, for guiding or concentrating the magnetic flux, e.g. to the magnetic sensor · CPC title

• B82Y25/00 Primary

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

• H01L43/12

  Electricity · mapped topic

• 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