MAGNETIC SENSOR AND PRODUCTION METHOD THEREOF

• US 20090015251A1
• Filed: 06/12/2008
• Published: 01/15/2009
• Est. Priority Date: 06/13/2007
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: AZUMI, Junichi, Fuse, Akihiro, Kou, Futoyoshi
• Granted Patent: US 8,134,361 B2
• Time in Patent Office: Days
• US Class Current: 324/247
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A magnetic sensor is disclosed that has plural axes at the same time, able to be fabricated in a small number of steps. The magnetic sensor includes a substrate; and plural sensor bridge circuits each including a pair of magnetic field detectors and a pair of fixed resistors on the substrate, the pair of the magnetic field detectors and the pair of the fixed resistors being connected to form a bridge circuit, each of the magnetic field detectors being formed of a magneto-resistance effect element, and magnetization directions of the magnetic field detectors intersect with each other in a three-dimensional manner. The substrate has plural inclined surfaces, normal directions of the inclined surfaces intersect with each other in a three-dimensional manner, and the pair of the magnetic field detectors in each of the sensor bridge circuits is arranged on the same inclined surface.

Claims

1. A magnetic sensor, comprising:

a substrate; and

a plurality of sensor bridge circuits each including a pair of magnetic field detectors and a pair of fixed resistors arranged on the substrate, the pair of the magnetic field detectors and the pair of the fixed resistors being connected to form a bridge circuit, each of the magnetic field detectors being formed of a magneto-resistance effect element, and magnetization directions of the magnetic field detectors intersect with each other in a three-dimensional manner,

wherein

the substrate has a plurality of inclined surfaces, and normal directions of the inclined surfaces intersect with each other in a three-dimensional manner, and

the pair of the magnetic field detectors in each of the sensor bridge circuits is arranged on the same inclined surface.

3. The magnetic sensor as claimed in claim 1, wherein

the substrate is formed of a (100) single crystal silicon wafer, and has a plurality of inclined surfaces of normal directions intersecting with each other in a three-dimensional manner, each of the inclined surfaces being a (111) orientation crystal plane forming an angle of 55 degrees relative to a surface of the substrate, and

the pair of the magnetic field detectors in each of the sensor bridge circuits is arranged on the same inclined surface.

5. The magnetic sensor as claimed in claim 1, wherein each of the fixed resistors includes a magneto-resistance effect element formed of the same layer configuration as the magnetic field detectors, and is covered by a magnetic shielding member with an insulating member of electrical insulation in between.

7. The magnetic sensor as claimed in claim 1, wherein the fixed resistors are arranged on the inclined surfaces formed on the substrate.

9. The magnetic sensor as claimed in claim 1, wherein the magneto-resistance effect element includes a tunnel magneto-resistance effect element.

2. A magnetic sensor, comprising:

a substrate; and

a first sensor bridge circuit, a second sensor bridge circuit, and a third sensor bridge circuit, each of the first sensor bridge circuit, the second sensor bridge circuit, and the third sensor bridge circuit including a pair of magnetic field detectors and a pair of reference resistors arranged on the substrate and connected to form a bridge circuit, each of the magnetic field detectors being formed of a magneto-resistance effect element, each of the reference resistors having a constant resistance value not influenced by an external magnetic field, and magnetization directions of the magnetic field detectors intersect with each other in a three-dimensional manner,

wherein

the substrate has a plurality of inclined surfaces, and normal directions of the inclined surfaces intersect with each other in a three-dimensional manner, and

the magnetic field detectors in each of the first sensor bridge circuit, the second sensor bridge circuit, and the third sensor bridge circuit are arranged on the inclined surfaces having normal directions intersecting with each other in a three-dimensional manner, and

the pair of the magnetic field detectors in the same one of the first sensor bridge circuit, the second sensor bridge circuit, and the third sensor bridge circuit is arranged on the inclined surface having the same normal direction.

4. The magnetic sensor as claimed in claim 2, wherein

the substrate is formed of a (100) single crystal silicon wafer, and has a plurality of inclined surfaces of normal directions intersecting with each other in a three-dimensional manner, each of the inclined surfaces being a (111) orientation crystal plane forming an angle of 55 degrees relative to a surface of the substrate,

the magnetic field detectors in each of the first sensor bridge circuit, the second sensor bridge circuit, and the third sensor bridge circuit are arranged on the inclined surfaces having normal directions intersecting with each other in a three-dimensional manner, and

the pair of the magnetic field detectors in the same one of the first sensor bridge circuit, the second sensor bridge circuit, and the third sensor bridge circuit is arranged on the inclined surface having the same normal direction.

6. The magnetic sensor as claimed in claim 2, wherein each of the fixed resistors includes a magneto-resistance effect element formed of the same layer configuration as the magnetic field detectors, and is covered by a magnetic shielding member with an insulating member of electrical insulation in between.

8. The magnetic sensor as claimed in claim 2, wherein the fixed resistors are arranged on the inclined surfaces formed on the substrate.

10. The magnetic sensor as claimed in claim 2, wherein the magneto-resistance effect element includes a tunnel magneto-resistance effect element.

11. A method of producing a magnetic sensor, comprising the steps of:

preparing a substrate;

forming a plurality of inclined surfaces on the substrate, and normal directions of the inclined surfaces intersect with each other in a three-dimensional manner,

arranging a pair of magnetic field detectors in each of a plurality of sensor bridge circuits in the same inclined surface, each of the sensor bridge circuits including the pair of magnetic field detectors and a pair of fixed resistors arranged on the substrate, the pair of the magnetic field detectors and the pair of the fixed resistors being connected to form a bridge circuit, each of the magnetic field detectors being formed of a magneto-resistance effect element, and

magnetizing a pinned layer of each of the magnetic field detectors by applying, while heating the substrate, a magnetic field in a direction perpendicular to a surface of the substrate.

12. The method as claimed in claim 11, further comprising the step of:

covering each of the fixed resistors by a magnetic shielding member with an insulating member of electrical insulation in between,

wherein

each of the fixed resistors includes a magneto-resistance effect element formed of the same layer configuration as the magnetic field detectors.

13. The method as claimed in claim 11, wherein the magneto-resistance effect element includes a tunnel magneto-resistance effect element.