Process integration of a single chip three axis magnetic field sensor

Patent metadata

Field	Value
Publication number	US-9269891-B2
Application number	US-201313972637-A
Country	US
Kind code	B2
Filing date	Aug 21, 2013
Priority date	Mar 31, 2010
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

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 three axis magneto-resistive sensor, the method comprising:
etching a plurality of first trenches in a first insulating material disposed on a substrate, wherein each first trench includes a plurality of side walls;
forming first flux guides in the plurality of first trenches by depositing a magnetically permeable material on at least two side walls of each of the plurality of first trenches;
depositing a second insulating material in each of the first plurality of trenches, wherein the second insulating material is deposited on the first insulating material and adjacent to the first flux guides;
forming a first plurality of magneto-resistive sensor elements on the second insulating material, wherein each sensor element of the first plurality of magneto-resistive sensor elements is juxtaposed to and laterally offset from an associated first flux guide;
forming a first bridge circuit by electrically interconnecting the magneto-resistive sensor elements of the first plurality of magneto-resistive sensor elements;
forming a second plurality of magneto-resistive sensor elements on the second insulating material;
forming a second bridge circuit by electrically interconnecting the magneto-resistive sensor elements of the second plurality of magneto-resistive sensor elements;
forming a third plurality of magneto-resistive sensor elements on the second insulating material;
forming a third bridge circuit by electrically interconnecting the magneto-resistive sensor elements of the third plurality of magneto-resistive sensor elements; and
depositing a third insulating material on or over the first, second, and third pluralities of magneto-resistive sensor elements,
wherein the first second, and third pluralities of magneto-resistive sensor elements are formed in a plane.

2. The method of claim 1 , wherein forming each of the first plurality of magneto-resistive sensor elements on the second insulating material includes forming a first reference layer having a first pinning direction,
wherein forming each of the second plurality of magneto-resistive sensor elements on the second insulating material includes forming a second reference layer having a second pinning direction, and
wherein forming each of the third plurality of magneto-resistive sensor elements on the second insulating material includes forming a third reference layer having a third pinning direction.

3. The method of claim 1 , wherein forming each magneto-resistive sensor element of the first, second, and third pluralities of magneto-resistive sensor elements includes:
forming a reference layer;
forming an intermediate layer on the reference layer; and
forming a sensing layer on the intermediate layer,
wherein forming the reference layer of each magneto-resistive sensor element of the first plurality of magneto-resistive sensor elements includes forming a first reference layer having a first pinning direction,
wherein forming the reference layer of each magneto-resistive sensor element of the second plurality of magneto-resistive sensor elements includes forming a second reference layer having a second pinning direction which is different from the first pinning direction, and
wherein forming the reference layer of each magneto-resistive sensor element of the third plurality of magneto-resistive sensor elements includes forming a third reference layer having a third pinning direction which is different from the first and second pinning directions.

4. The method of claim 3 , wherein the intermediate layer is an insulating layer.

5. The method of claim 3 , wherein forming the reference layer of each magneto-resistive sensor element of the first, second, and third pluralities of magneto-resistive sensor elements includes:
forming an antiferromagnetic pinning layer; and
forming a ferromagnetic layer on the antiferromagnetic pinning layer.

6. The method of claim 3 , wherein forming the reference layer of each magneto-resistive sensor element of the first, second, and third pluralities of magneto-resistive sensor elements includes:
forming a synthetic antiferromagnetic stack.

7. The method of claim 1 , wherein the magnetically permeable material includes at least one of nickel, iron, and cobalt.

8. The method of claim 1 , wherein forming each magneto-resistive sensor element of the first, second, and third pluralities of magneto-resistive sensor elements includes:
forming a reference layer;
forming a third insulating material on the reference layer; and
forming a sensing layer on the third insulating material.

9. The method of claim 1 , wherein forming the first flux guides in the plurality of first trenches includes:
depositing the magnetically permeable material into each first trench of the plurality of first trenches; and
back sputtering at least a portion of the magnetically permeable material from a bottom of each first trench of the plurality of first trenches, and leaving the magnetically permeable material on the at least two side walls of each first trench of the plurality of first trenches.

10. The method of claim 1 , wherein forming the first flux guides in the plurality of first trenches includes:
depositing one or more layers of at least one of nickel, iron, cobalt, and alloys thereof into each first trench of the plurality of first trenches.

11. The method of claim 1 , wherein forming the first flux guides in the plurality of first trenches includes:
providing one or more layers of at least one of nickel, iron, cobalt, and alloys thereof on the at least two side walls of each first trench of the plurality of first trenches.

12. The method of claim 1 , further including:
depositing a conductive material in the plurality of first trenches, on the second insulating material, and adjacent to the first flux guides.

13. The method of claim 1 , further including:
etching a plurality of second trenches in the third insulating material, wherein each second trench of the plurality of second trenches includes at least two side walls, wherein each second trench is juxtaposed to and laterally offset from an associated sensor element of the first plurality of magneto-resistive sensor elements;
forming second flux guides in the plurality of second trenches, wherein each second flux guide includes a second magnetically permeable material disposed on the at least two side walls of an associated second trench; and
depositing a fourth insulating material on the third insulating material and the second flux guides.

14. The method of claim 13 , wherein the second magnetically permeable material includes at least one of nickel, iron, cobalt, and alloys thereof.

15. The method of claim 13 , wherein forming the second flux guides in the plurality of second trenches includes:
depositing the second magnetically permeable material into each second trench of the plurality of second trenches; and
back sputtering at least a portion of the second magnetically permeable material from the bottom of each second trench of the plurality of second trenches, and leaving the second magnetically permeable material on the at least two side walls of each second trench of the plurality of second trenches.

16. The method of claim 13 , wherein forming the second flux guides in the plurality of second trenches includes:
depositing one or more layers of at least one of nickel, iron, cobalt, and alloys thereof into each second trench of the plurality of second trenches.

17. The method of claim 13 , wherein forming the second flux guides in t

Assignees

• Everspin Technologies Inc

Inventors

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

Classifications

• H01L43/12 Primary

  Electricity · mapped topic

• H01L27/22

  Electricity · mapped topic

• 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

• G01R33/093

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