Magnetic MEMS sensors

• US 20080052932A1
• Filed: 09/01/2006
• Published: 03/06/2008
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Xue, Song Sheng, Amin, Nurul, Ryan, Patrick Joseph
• Granted Patent: US 7,509,748 B2
• Time in Patent Office: Days
• US Class Current: 33/356
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26

Abstract

The disclosure relates to micro-electromechanical systems (MEMS) and magnetic MEMS sensors. The sensors include a substrate having a surface, a first magnetic field detector positioned on the surface, a second magnetic field detector positioned on the surface proximate to the first magnetic field detector, and a third magnetic field detector positioned on the surface proximate to the first and second magnetic field detectors. Each of the first, second and third magnetic field detector is capable of detecting external magnetic fields that are mutually orthogonal along three directions. In certain embodiments, the magnetic MEMS sensors may be useful as electronic compasses. The disclosure also relates to fabricating a magnetic MEMS device, such as an electronic compass, from or on a single wafer, which includes multiple MEMS sensors.

Claims

1. A magnetic field sensor comprising:

a substrate having a surface;

a first magneto-impedance magnetic field detector positioned on the surface;

a second magneto-impedance magnetic field detector positioned on the surface proximate to the first magneto-impedance magnetic field detector; and

a third magnetic field detector positioned on the surface proximate to the first and second magneto-impedance magnetic field detectors,

wherein each of the first, second and third magnetic field detector is capable of detecting external magnetic fields that are mutually orthogonal along three directions.

2. The magnetic field sensor according to claim 1, wherein the third magnetic field detector is selected from the group consisting of a magneto-electric detector, a magneto-resistive detector, a magneto-impedance magnetic field detector, a magneto-strictive detector, a flux guided magneto-resistive detector, a giant magneto-resistive detector, a giant magneto-electric detector, a giant magneto-impedance magnetic field detector or a tunneling giant magneto-resistive detector.

3. The magnetic field sensor according to claim 1, wherein the first and second magneto-impedance magnetic field detectors are oriented substantially orthogonal to each other.

4. The magnetic field sensor according to claim 3, wherein the third magnetic field detector is oriented substantially orthogonal to each of the first and second magneto-impedance magnetic field detectors.

5. The magnetic field sensor according to claim 1, further comprising at least one electronic circuit formed on or within the substrate, wherein the electronic circuit is communicably connected to at least one of the first and second magneto-impedance magnetic field detectors and the third magnetic field detector.

6. The magnetic field sensor according to claim 5, wherein the electronic circuit includes at least one electronic circuit element selected from the group consisting of a via, an electrode, a power source, a pre-amplifier, a modulator, a demodulator, an oscillator, a filter, an analog to digital converter, a digital to analog converter, or a digital signal processor.

7. The magnetic field sensor according to claim 1, wherein the substrate comprises one or more of the group consisting of polysilicon, single crystalline silicon, silicon-germanium, silicon carbide, silicon oxide, silicon dioxide, silicon nitride, silicon oxynitrite, metals, metal alloys, ceramics, or polymers.

8. The magnetic field sensor according to claim 1, wherein the external magnetic field is the earth'"'"'s magnetic field.

9. A compass comprising:

a substrate having a first, second, third and fourth surface, wherein the first and second surface are substantially parallel and the third and fourth surface are each sloped relative to the first and second surface;

a first magnetic field detector positioned on the second surface;

a second magnetic field detector positioned on the third surface; and

a third magnetic field detector positioned on the fourth surface proximate to and substantially orthogonal to both the first and second magnetic field detectors,

wherein each of the first, second and third magnetic field detector is capable of detecting external magnetic fields that are mutually orthogonal along three directions.

10. The compass according to claim 9, wherein the third magnetic field detector is selected from the group consisting of a magneto-electric detector, a magneto-resistive detector, a magneto-impedance magnetic field detector, a magneto-strictive detector, a flux guided magneto-resistive detector, a giant magneto-resistive detector, a giant magneto-electric detector, a giant magneto-impedance magnetic field detector or a tunneling giant magneto-resistive detector.

11. The compass according to claim 9, wherein first, second and third magnetic field detectors are each a magneto-impedance magnetic field detector.

12. The compass according to claim 9, wherein first, second and third magnetic field element are each a magneto-electric field element.

13. The compass according to claim 9, further comprising at least one electronic circuit formed on or within the substrate, wherein the electronic circuit is communicably connected to at least one of the first and second magneto-impedance magnetic field detectors and the third magnetic field detector.

14. The compass according to claim 13, wherein the electronic circuit includes at least one electronic circuit element selected from the group consisting of a via, an electrode, a power source, a pre-amplifier, a modulator, a demodulator, an oscillator, a filter, an analog to digital converter, a digital to analog converter, or a digital signal processor.

15. The compass according to claim 9, wherein the substrate comprises one or more of the group consisting of polysilicon, single crystalline silicon, silicon-germanium, silicon carbide, silicon oxide, silicon dioxide, silicon nitride, silicon oxynitrite, metals, metal alloys, ceramics, or polymers.

16. The compass according to claim 9, wherein the external magnetic field is the earth'"'"'s magnetic field.

17. A three-dimensional compass comprising:

a base having a surface oriented relative to an external magnetic field;

a structure formed on the surface, wherein the structure comprises a plurality of side faces, wherein each side face defines an acute angle relative to line drawn normal to the surface, and wherein each side face converges to an apex defining a generally substantially planar plateau substantially parallel to the surface;

a first magneto-impedance magnetic field detector positioned on the plateau;

a second magneto-impedance magnetic field detector positioned on one of the side faces, wherein the second magneto-impedance magnetic field detector is positioned substantially orthogonal to the first magneto-impedance magnetic field detector; and

a third magnetic field detector positioned on one of the side faces, wherein the third magnetic field detector is positioned substantially orthogonal to both the first and second magneto-impedance magnetic field detectors,

wherein each of the first, second and third magnetic field detector are capable of detecting external magnetic fields that are mutually orthogonal along three directions.

18. The three-dimensional compass according to claim 17, wherein the third magnetic field detector is selected from the group consisting of a magneto-electric detector, a magneto-resistive detector, a magneto-impedance magnetic field detector, a magneto-strictive detector, a flux guided magneto-resistive detector, a giant magneto-resistive detector, a giant magneto-electric detector, a giant magneto-impedance magnetic field detector or a tunneling giant magneto-resistive detector.

19. The three-dimensional compass according to claim 17, further comprising at least one electronic circuit formed on or within the substrate, wherein the electronic circuit is communicably connected to at least one of the first and second magneto-impedance magnetic field detectors and the third magnetic field detector.

20. The three-dimensional compass according to claim 19, wherein the electronic circuit includes at least one electronic circuit element selected from the group consisting of a via, an electrode, a power source, a pre-amplifier, a modulator, a demodulator, an oscillator, a filter, an analog to digital converter, a digital to analog converter, or a digital signal processor.

21. The three-dimensional compass according to claim 17, wherein the external magnetic field is the earth'"'"'s magnetic field.

22. A method of making a compass, the method comprising:

providing a substrate;

fabricating a first, second and third magnetic field detector that adjoin the substrate, wherein each of the first, second and third magnetic field detector is capable of detecting external magnetic fields that are mutually orthogonal along three directions.

23. The method of making a compass according to claim 22, the method further comprising fabricating the substrate to have a first, second, third and fourth surface, wherein the first and second surface are substantially parallel, and the third and fourth surface are sloped relative to the first and second surface.

24. The method of making a compass according to claim 23, the fabricating a first, second, and third magnetic field detector step further comprising fabricating the first magnetic field detector on the second surface, fabricating the second magnetic field detector on the third surface, and fabricating the third magnetic field detector on the fourth surface.

25. The method of making a compass according to claim 22, the fabricating a first, second, and third magnetic field detector step further comprising fabricating the first, second and third magnetic field detector so that each is substantially orthogonal to each other.

26. The method of making a compass according to claim 22, wherein the substrate has a surface, and the first and second magnetic field detector are each fabricated on the surface substantially orthogonal to each other.

27. The method of making a compass according to claim 26, wherein the third magnetic field detector is fabricated to be generally orthogonal to the first and second magnetic field detector.

28. The method of making a compass according to claim 27, wherein the first and second magnetic field detectors are magneto-impedance sensors having helical coils.

29. The method of making a compass according to claim 28, wherein the third magnetic field detector is a magneto-impedance sensor having pancake coils.