Methods of manufacturing a magnetic field sensor

Patent metadata

Field	Value
Publication number	US-11024799-B2
Application number	US-201916360099-A
Country	US
Kind code	B2
Filing date	Mar 21, 2019
Priority date	Mar 31, 2010
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A semiconductor process integrates three bridge circuits, each include magnetoresistive sensors coupled as a Wheatstone bridge on a single chip to sense a magnetic field in three orthogonal directions. The process includes various deposition and etch steps forming the magnetoresistive sensors and a plurality of flux guides on one of the three bridge circuits for transferring a “Z” axis magnetic field onto sensors orientated in the XY plane.

First claim

The invention claimed is:

1. A method of manufacturing an integrated magneto-resistive sensor, the method comprising:
forming a plurality of magneto-resistive sensor elements on or over a substrate, wherein each magneto-resistive sensor element comprises a reference layer and a sensing layer,
forming conductors to electrically connect the plurality of magneto-resistive sensor elements into a single circuit;
depositing a first insulating material over each of the plurality of magneto-resistive sensor elements; and
forming a plurality of flux guides on or in the first insulating material or on or in the substrate, wherein (i) each flux guide of the plurality of flux guides comprises a magnetic material; (ii) an entirety of a first flux guide of the plurality of flux guides is adjacent to and laterally offset from a first side of at least one magneto-resistive sensor element of the plurality of magneto-resistive sensor elements; and (iii) an entirety of a second flux guide of the plurality of flux guides is adjacent to an laterally offset from a second side of at least one magneto-resistive sensor element of the plurality of magneto-resistive sensor elements.

2. The method of claim 1 , wherein the magnetic material of the plurality of flux guides comprises one or more of nickel, iron, cobalt, and/or an alloy including one or more of nickel, iron, and cobalt.

3. The method of claim 1 , wherein forming the plurality of magneto-resistive sensor elements includes:
forming an intermediate dielectric layer between the reference layer and the sensing layer.

4. The method of claim 1 , wherein forming the plurality of magneto-resistive sensor elements includes:
forming an intermediate dielectric layer between the reference layer and the sensing layer;
wherein the reference layer of each magneto-resistive sensor element includes a pinning direction; and
wherein forming the sensing layer of each magneto-resistive sensor element includes:
depositing a magnetic material over the intermediate dielectric layer, and thereafter, patterning the magnetic material into the sensing layer, wherein the magnetic material includes an easy axis of a magnetization direction that is orthogonal to the pinning direction of the reference layer.

5. The method of claim 1 , wherein each magneto-resistive sensor element is a magnetic tunnel junction sensor element.

6. The method of claim 1 , wherein forming conductors to electrically connect the magneto-resistive sensor elements includes forming conductors to electrically connect the magneto-resistive sensor elements into a bridge circuit including input conductors and output conductors.

7. The method of claim 1 , wherein forming conductors to electrically connect the magneto-resistive sensor elements includes forming conductors to electrically connect the magneto-resistive sensor elements into a bridge circuit including input conductors and output conductors, and wherein the method further include:
providing a voltage meter; and
electrically connecting the output conductors of the bridge circuit to the voltage meter.

8. The method of claim 1 , wherein forming conductors to electrically connect the magneto-resistive sensor elements includes forming conductors to electrically connect the magneto-resistive sensor elements into a bridge circuit including input conductors and output conductors, and wherein the method further includes:
providing a voltage meter;
electrically connecting the output conductors of the bridge circuit to the voltage meter; and
electrically connecting the input conductors of the bridge circuit to electrical power terminals.

9. The method of claim 1 , wherein forming the plurality of flux guides on or in the first insulating material or on or in the substrate includes forming one or more bars, comprising a magnetic material, adjacent to and entirely offset from one or more magneto-resistive sensor elements.

10. The method of claim 1 , wherein forming the plurality of flux guides on or in the first insulating material or on or in the substrate includes forming one or more bars, comprising a magnetic material, adjacent to and entirely offset from one or more edges of one or more magneto-resistive sensor elements.

11. The method of claim 1 , wherein forming the plurality of flux guides on or in the first insulating material or on or in the substrate includes forming one or more bars, comprising a nickel-iron alloy, wherein each bar of the one or more bars is adjacent to and entirely offset from a side of at least one magneto-resistive sensor element.

12. The method of claim 1 , wherein:
forming conductors to electrically connect the plurality of magneto-resistive sensor elements further includes forming conductors to electrically interconnect (i) a first subset of the magneto-resistive sensor elements into a first bridge circuit and (ii) a second subset of magneto-resistive sensor elements into a second bridge circuit, and
forming the plurality of flux guides on or in the first insulating material or on or in the substrate further includes forming flux guides on or in the first insulating material or on or in the substrate adjacent to and entirely offset from one or more magneto-resistive sensor elements of the first subset of the magneto-resistive sensor elements.

13. The method of claim 1 , wherein the single circuit includes four sensors arranged in a first plane, wherein each of the four sensors is configured to sense a magnetic field in a direction orthogonal to the first plane, and wherein at least two magneto-resistive sensor elements of the plurality of magneto-resistive sensor elements are connected for differential measurement.

14. The method of claim 1 , wherein the single circuit includes four sensors connected by one wire to form the single circuit, wherein the four sensors are arranged in a first plane, and wherein each of the four sensors is configured to sense a magnetic field in a direction orthogonal to the first plane.

15. A method of manufacturing an integrated magneto-resistive sensor, the method comprising:
forming a plurality of magneto-resistive sensor elements on or over a substrate, wherein each magneto-resistive sensor element comprises a reference layer and a sensing layer,
forming conductors to electrically connect the plurality of magneto-resistive sensor elements into a single circuit;
depositing a first insulating material over each of the plurality of magneto-resistive sensor elements; and
forming one or more flux guides on or in the first insulating material or on or in the substrate, wherein (i) the one or more flux guides comprise a magnetic material; and (ii) an entirety of each flux guide of the one or more flux guides is adjacent to and laterally offset from at least one associated magneto-resistive sensor element of the plurality of magneto-resistive sensor elements.

16. The method of claim 15 , wherein the magnetic material of the plurality of flux guides comprises one or more of nickel, iron, cobalt, and/or an alloy including one or more of nickel, iron, and cobalt.

17. The method of claim 15 , wherein forming the plurality of magneto-resistive sensor elements includes:
forming an intermediate dielectric layer between the reference layer and the sensing layer;
wherein the reference layer of each magneto-resistive sensor element includes a pinning direction; and
wherein forming the sensing layer of each magneto-resistive sensor element includes:
depositing a magnetic material over the intermediate dielectric layer, and thereafter, patterning the magnetic material into the sensing la

Assignees

• Everspin Technologies Inc

Inventors

• Whig Renu
• Mather Phillip
• Smith Kenneth
• Aggarwal Sanjeev
• Slaughter Jon
• Rizzo Nicholas

Classifications

• 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

• G01R33/093

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

• G01R33/098

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

• G01R33/0052

  Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips (devices based on galvano-magnetic effect or the like H10N50/85) · CPC title

• B82Y25/00 Primary

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