Three axis magnetic sensor device and method

• US 8,486,723 B1
• Filed: 08/19/2010
• Issued: 07/16/2013
• Est. Priority Date: 08/19/2010
• Status: Active Grant

• Current Assignee: Movella Incorporated (Movella Holdings, Inc.)
• Original Assignee: mCube, Inc.
• Inventors: Wan, Hong, Yang, Xiao Charles
• Primary Examiner(s): Valentine, Jami M
• Application Number:
  US12/859,631
• Time in Patent Office: 1,062 Days
• Field of Search: 438/3, 257421-427
• US Class Current: 438/3
• CPC Class Codes: G01R 33/0206 Three-component magnetometers
• CPC Class Codes: G01R 33/0286 comprising microelectromechanical systems [MEMS] MEMS devices in general B81B
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 59/00 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

Abstract

A method and structure for a three-axis magnetic field sensing device is provided. The device includes a substrate, an IC layer, and preferably three magnetic field sensors coupled to the IC layer. A nickel-iron magnetic field concentrator is also provided.

Claims

1. A method for fabricating a device for sensor magnetic fields, the method comprising:

providing a substrate member having a surface region;

removing at least one portion of the substrate member;

forming an integrated circuit (IC) layer overlying the substrate member;

forming a first magnetic field sensor element comprising at least a first material and configured to detect at least an x-axis direction, the first magnetic field sensor element being operably coupled to the IC layer;

forming a second magnetic field sensor element comprising at least the first material and configured to detect at least a y-axis direction, the second magnetic field sensor element being operably coupled to the IC layer;

forming a third magnetic field sensor element comprising at least the first material and configured to detect at least a z-axis direction, the third magnetic field sensor element being operably coupled to the IC layer;

forming at least one magnetic field concentrator spatially disposed overlying at least one portion of the substrate member, the magnetic field concentrator being formed within a vicinity of the third magnetic field sensor element; and

forming at least one passivation material overlying the first, second, and third magnetic field sensor elements and the surface region;

wherein all of the x-axis, y-axis, and z-axis directions are configured in a mutually orthogonal manner.

2. The method of claim 1 wherein the substrate member comprises a silicon material, a dielectric material, or a polymer.

3. The method of claim 1 wherein the substrate member has at least one portion patterned through a wet etching, dry etching, deep reactive-ion etching (DRIE), or mechanical process.

4. The method of claim 1 wherein the IC layer comprises a silicon material, a dielectric material, or a metal material.

5. The method of claim 1 wherein the IC layer comprises at least one IC device.

6. The method of claim 1 wherein the first, second, and third magnetic field sensor elements comprise ordinary magneto-resistive (OMR) devices, anisotropic magneto-resistive (AMR) devices, giant magneto-resistive (GMR) devices, or tunnel junction magneto-resistive (TMR) devices.

7. The method of claim 1 wherein the first, second, and third magnetic field sensor elements comprise thin film device(s), the thin film device(s) being deposited overlying at least one portion of the surface region.

8. The method of claim 7 wherein the thin film device(s) are deposited by a sputtering process.

9. The method of claim 1 wherein the first, second, and third magnetic field sensor elements are formed as a Wheatstone bridges, half bridges, or single elements.

10. The method of claim 1 wherein the first magnetic field sensor element is configured to be 45 degrees away from a crystal easy axis direction.

11. The method of claim 1 wherein the first magnetic field sensor element is configured to detect magnetic fields in the x-axis direction.

12. The method of claim 1 wherein the second magnetic field sensor element is configured to be −

45 degrees away from a crystal easy axis direction.

13. The method of claim 1 wherein the second magnetic field sensor element is configured to detect magnetic fields in the y-axis direction.

14. The method of claim 1 wherein the first and second magnetic field sensor elements are configured to be symmetrical across a crystal hard axis.

15. The method of claim 1 wherein the third magnetic field sensor is configured to a direction on a crystal hard axis or a crystal easy axis.

16. The method of claim 1 wherein the third magnetic field sensor element is aligned to the first or second magnetic sensor element.

17. The method of claim 1 wherein the third magnetic field sensor element is configured to detect magnetic fields in the z-axis direction, the third magnetic field sensor element being able to detect vertical magnetic fields via the field concentrator(s).

18. The method of claim 1 further comprising a conductive strap disposed within a vicinity of the first, second, and third magnetic field sensor elements.

19. The method of claim 18 wherein the conductive strap comprises a metal or metal alloy.

20. The method of claim 1 wherein the field concentrator(s) comprise a nickel iron (NiFe) material or a nickel iron cobalt (NiFeCo) material.

21. The method of claim 1 wherein the field concentrator(s) comprise permalloy materials, the permalloy materials having high permeability.

22. The method of claim 1 wherein the field concentrator(s) are formed via an electricplating process or a sputtering process.