Methods of manufacturing a magnetic field sensor

Patent metadata

Field	Value
Publication number	US-9893274-B2
Application number	US-201615388650-A
Country	US
Kind code	B2
Filing date	Dec 22, 2016
Priority date	Mar 31, 2010
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

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:
providing a substrate;
depositing a first etch stop layer on or over the substrate;
depositing a first insulating material on or over the first etch stop layer;
etching a first plurality of trenches through the first insulating material to the first etch stop layer;
forming a first plurality of flux guides, wherein forming the first plurality of flux guides comprises:
depositing a magnetically permeable material within each trench of the first plurality of trenches; and
back-sputtering the magnetically permeable material away from a bottom surface of each trench of the first plurality of trenches; and

forming a first plurality of magneto-resistive sensor elements on or over the first insulating material, wherein at least one magneto-resistive sensor element of the first plurality of magneto-resistive sensor elements is associated with at least one flux guide of the first plurality of flux guides, and wherein the at least one magneto-resistive sensor element is offset from the at least one flux guide of the first plurality of flux guides; and
forming first conductors to electrically connect the first plurality of magneto-resistive sensor elements.

2. The method of claim 1 , wherein:
forming first conductors to electrically connect the first plurality of magneto-resistive sensor elements includes forming a first circuit by electrically connecting the magneto-resistive sensor elements of the first plurality of magneto-resistive sensor elements.

3. The method of claim 2 , wherein the first circuit is a bridge circuit, and wherein the method further includes:
connecting the bridge circuit to a voltage source.

4. The method of claim 1 , wherein forming the first plurality of magneto-resistive sensor elements includes electrically connecting the first plurality of magneto-resistive sensor elements to form a first bridge circuit.

5. The method of claim 1 , wherein the formed first conductors electrically connect the first plurality of magneto-resistive sensor elements to form a first circuit.

6. The method of claim 5 , wherein the first circuit is a bridge circuit.

7. The method of claim 1 , wherein the at least one flux guide of the first plurality of flux guides includes at least one of nickel, a nickel alloy, iron, an iron alloy, cobalt, and a cobalt alloy.

8. The method of claim 1 , wherein the at least one magneto-resistive sensor element is formed above the at least one flux guide of the first plurality of flux guides.

9. The method of claim 1 , wherein the magneto-resistive sensor elements are magnetic tunnel junction sensor elements.

10. The method of claim 1 , further comprising:
forming a second plurality of magneto-resistive sensor elements; and
forming second conductors to electrically connect the second plurality of magneto-resistive sensor elements.

11. The method of claim 1 , further comprising:
connecting the first plurality of magneto-resistive sensor elements in a circuit such that, in operation, the circuit is configured to subtract a resistance of the least one magneto-resistive sensor element from a resistance of another magneto-resistive sensor element of the first plurality of magneto-resistive sensor elements.

12. The method of claim 1 , further comprising:
forming a first bridge circuit by electrically connecting the magneto-resistive sensor elements of the first plurality of magneto-resistive sensor elements;
forming a second plurality of magneto-resistive sensor elements; and
forming a second bridge circuit by electrically connecting the magneto-resistive sensor elements of the second plurality of magneto-resistive sensor elements.

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

14. The method of claim 1 , wherein forming the first plurality of magneto-resistive sensor elements includes:
forming a reference layer,
forming a sensing layer, and
forming an intermediate layer between the reference and sensing layers, wherein the intermediate layer includes an insulating material.

15. The method of claim 1 , wherein the sensing layer includes a magnetization direction configured to change when exposed to an external magnetic field.

16. The method of claim 1 , further comprising:
depositing a second insulating material on or over the first plurality of magneto-resistive sensor elements; and
forming a second plurality of flux guides on or over the second insulating material.

17. The method of claim 16 , wherein at least one flux guide of the second plurality of flux guides is disposed above the at least one magneto-resistive sensor element.

18. A method of manufacturing an integrated magneto-resistive sensor, the method comprising:
providing a substrate;
depositing a first etch stop layer on or over the substrate depositing a first insulating material on or over the first etch stop layer;
etching a first plurality of trenches through the first insulating material to the first etch stop layer;
forming a first plurality of flux guides, wherein the flux guides comprise a magnetic material, and wherein forming the first plurality of flux guides comprises:
depositing the magnetic material within each trench of the first plurality of trenches; and
back-sputtering the magnetic material away from a bottom surface of each trench of the first plurality of trenches;

forming a plurality of magneto-resistive sensor elements on or over the first insulating material, wherein forming the plurality of magneto-resistive sensor elements includes:
forming a reference layer,
forming a sensing layer, and
forming an intermediate layer between the reference layer and the sensing layer; and

forming conductors to (i) electrically interconnect a first subset of the magneto-resistive sensor elements into a first bridge circuit and (ii) electrically interconnect a second subset of the magneto-resistive sensor elements into a second bridge circuit,
wherein each magneto-resistive sensor element of the first subset of the magneto-resistive sensor elements is adjacent to and offset from an associated flux guide of the first plurality of flux guides.

19. The method of claim 18 , wherein forming conductors to electrically interconnect a first subset of the magneto-resistive sensor elements into a first bridge circuit further includes forming conductors to electrically interconnect the first subset of the magneto-resistive sensor elements into the first bridge circuit having (i) input conductors configured for connection to a voltage source and (ii) output conductors configured for connection to a detection circuit.

20. The method of claim 18 , wherein the magnetic material of the flux guides comprises one or more of nickel, a nickel alloy, iron, an iron alloy, cobalt, and a cobalt alloy.

21. The method of claim 18 , wherein the intermediate layer of each magneto-resistive sensor element is a dielectric material.

22. The method of claim 18 , further comprising:
depositing a second insulating material on or over the plurality of magneto-resistive sensor elements; and
forming a second plurality of flux guides on or over the second insulating material.

Assignees

• Everspin Technologies Inc

Inventors

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

Classifications

• G01R33/098

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

• H01L43/08

  Electricity · mapped topic

• 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

• H01L27/22

  Electricity · mapped topic

• H01L43/12 Primary

  Electricity · mapped topic