Magnetic sensor using giant magnetoresistive elements and method for manufacturing the same

• US 7,589,939 B2
• Filed: 09/28/2005
• Issued: 09/15/2009
• Est. Priority Date: 09/28/2004
• Status: Expired due to Fees

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Wakul, Yukio, Omura, Masayoshi
• Primary Examiner(s): KLIMOWICZ, WILLIAM JOSEPH
• Application Number:
  US11/236,645
• Publication Number:
  US 20060072249A1
• Time in Patent Office: 1,448 Days
• Field of Search: 324/207.21, 324/252, 324/38.R, 360/324.11, 360/324.1, 360/324.12, 338/32.R
• US Class Current: 360/324.1
• 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: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] 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 magnetic sensor includes a single substrate, a conventional GMR element formed of a spin-valve film including a single-layer-pinned fixed magnetization layer, and a SAF element formed of a synthetic spin-valve film including a plural-layer-pinned fixed magnetization layer. When the spin-valve film intended to act as the conventional GMR element and the synthetic spin-valve film intended to act as the SAF element are subjected to the application of a magnetic field oriented in a single direction at a high temperature, they become giant magnetoresistive elements whose magnetic-field-detecting directions are antiparallel to each other. Since films intended to act as the conventional GMR element and the SAF element can be disposed close to each other, the magnetic sensor which has giant magnetoresistive elements whose magnetic-field-detecting directions are antiparallel to each other can be small.

Claims

1. A magnetic sensor comprising:

a single substrate;

a first giant magnetoresistive element disposed on the substrate, the first giant magnetoresistive element being formed of a single-layer-pinned spin-valve film comprising

a single-layer-pinned fixed magnetization layer including a single ferromagnetic layer and a pinning layer,

a free layer whose magnetization direction changes in response to an external magnetic field, and

a spacer layer made of a nonmagnetic conductive material, disposed between the ferromagnetic layer and the free layer,

wherein the magnetization of the ferromagnetic layer is fixed in a first direction by the pinning layer, so that the ferromagnetic layer serves as a pinned layer; and

a second giant magnetoresistive element disposed on the substrate, the second giant magnetoresistive element being formed of a plural-layer-pinned spin-valve film comprising

a plural-layer-pinned fixed magnetization layer including a first ferromagnetic layer, an exchange coupling layer adjoining the first ferromagnetic layer, a second ferromagnetic layer adjoining the exchange coupling layer, and a pinning layer adjoining the second ferromagnetic layer,

a free layer whose magnetization direction changes in response to an external magnetic field, and

a spacer layer made of a nonmagnetic conductive material disposed between the first ferromagnetic layer and the free layer, wherein the magnetization direction of the second ferromagnetic layer is fixed by the pinning layer and the magnetization direction of the first ferromagnetic layer is fixed in a second direction antiparallel to the first direction by exchange coupling of the first ferromagnetic layer and the second ferromagnetic layer with the exchange coupling layer therebetween, so that the first ferromagnetic layer serves as a pinned layer.

2. The magnetic sensor according to claim 1, wherein the first giant magnetoresistive element and the second giant magnetoresistive element are connected in a bridge configuration to form a circuit generating an output in response to a potential at a predetermined point of the circuit, the output increasing or decreasing monotonically as the intensity of a component of a magnetic field in a first direction applied to the magnetic sensor increases.

3. The magnetic sensor according to claim 1, comprising two of the first giant magnetoresistive elements and two of the second giant magnetoresistive elements,

wherein an end of one of the two first giant magnetoresistive elements is connected to an end of one of the two second giant magnetoresistive element to form a first sub-circuit, and an end of the other first giant magnetoresistive element is connected to an end of the other second giant magnetoresistive element to form a second sub-circuit,

wherein a first potential is applied to the other end of the first giant magnetoresistive element in the first sub-circuit and the other end of the second giant magnetoresistive element in the second sub-circuit, and a second potential different from the first potential is applied to the other end of the second giant magnetoresistive element in the first sub-circuit and the other end of the first giant magnetoresistive element in the second sub-circuit, and

wherein the magnetic sensor outputs a difference in potential between the junction where the first giant magnetoresistive element is connected to the second giant magnetoresistive element in the first sub-circuit and the junction where the first giant magnetoresistive element is connected to the second giant magnetoresistive element in the second sub-circuit.

4. The magnetic sensor according to claim 1, further comprising a third giant magnetoresistive element formed of the single-layer-pinned spin-valve film on the substrate, and a fourth giant magnetoresistive element formed of the plural-layer-pinned spin-valve film on the substrate, wherein the magnetization of the ferromagnetic layer in the third giant magnetoresistive element is fixed in a third direction perpendicular to the first direction, and the magnetization of the first ferromagnetic layer in the fourth giant magnetoresistive element is fixed in a fourth direction antiparallel to the third direction.

5. The magnetic sensor according to claim 4, wherein the first giant magnetoresistive element and the second giant magnetoresistive element are connected in a bridge configuration to form a circuit generating a first output in response to a potential at a predetermined point in the circuit that monotonically increases or decreases as the intensity of a component in the first direction of a magnetic field applied to the magnetic sensor increases, and wherein the third giant magnetoresistive element and the fourth giant magnetoresistive element are connected in a bridge configuration to form a circuit generating a second output in response to a potential at a predetermined point of the circuit that monotonically increases or decreases as the intensity of a component in the third direction of the magnetic field applied to the magnetic sensor increases.

6. The magnetic sensor according to claim 4, comprising two of the first giant magnetoresistive elements comprises, two of the second giant magnetoresistive elements, two of the third giant magnetoresistive elements, and two of the fourth giant magnetoresistive elements,

wherein an end of one of the two first giant magnetoresistive elements is connected to an end of one of the two second giant magnetoresistive elements to form a first sub-circuit;

an end of the other first giant magnetoresistive element is connected to an end of the other second giant magnetoresistive element to form a second sub-circuit;

a first potential is applied to the other end of the first giant magnetoresistive element in the first sub-circuit and the other end of the second giant magnetoresistive element in the second sub-circuit; and

a second potential different from the first potential is applied to the other end of the second giant magnetoresistive element in the first sub-circuit and the other end of the first giant magnetoresistive element in the second sub-circuit,

wherein an end of one of the two third giant magnetoresistive elements is connected to an end of one of the two fourth giant magnetoresistive elements to form a third sub-circuit;

an end of the other third giant magnetoresistive element is connected to an end of the other fourth giant magnetoresistive element to form a fourth sub-circuit;

a third potential is applied to the other end of the third giant magnetoresistive element in the third sub-circuit and the other end of the fourth giant magnetoresistive element in the fourth sub-circuit; and

a fourth potential different from the third potential is applied to the other end of the fourth giant magnetoresistive element in the third sub-circuit and the other end of the third giant magnetoresistive element in the fourth sub-circuit,

whereby the magnetic sensor is configured so as to generate a first output and a second output, the first output being a difference in potential between the junction where the first giant magnetoresistive element is connected to the second giant magnetoresistive element in the first sub-circuit and the junction where the first giant magnetoresistive element is connected to the second giant magnetoresistive element in the second sub-circuit, the second output being a difference in potential between the junction where the third giant magnetoresistive element is connected to the fourth giant magnetoresistive element in the third sub-circuit and the junction where the third giant magnetoresistive element is connected to the fourth giant magnetoresistive element in the fourth sub-circuit.

7. The magnetic sensor according to claim 1, comprising:

two of the first giant magnetoresistive elements;

two of the second giant magnetoresistive elements;

two of a third giant magnetoresistive elements each formed of the single-layer-pinned spin-valve film on the substrate, the magnetization of the ferromagnetic layer in each third giant magnetoresistive element being fixed in the second direction; and

two of a fourth giant magnetoresistive elements each formed of the plural-layer-pinned spin-valve film on the substrate, the magnetization of the first ferromagnetic layer in each fourth giant magnetoresistive element being fixed in the first direction,

wherein the two of the first giant magnetoresistive elements and the two of the second giant magnetoresistive elements are disposed close to each other in a first region; and

the two of the third giant magnetoresistive elements and the two of the fourth giant magnetoresistive elements are disposed close to each other in a second region apart from the first region;

wherein an end of one of the two of the first giant magnetoresistive elements is connected to an end of one of the two of the third giant magnetoresistive elements to form a first sub-circuit;

an end of the other first giant magnetoresistive element is connected to an end of the other third giant magnetoresistive element to form a second sub-circuit;

a first potential is applied to the other end of the first giant magnetoresistive element of the first sub-circuit and the other end of the third giant magnetoresistive element of the second sub-circuit;

a second potential different from the first potential is applied to the other end of the third giant magnetoresistive element of the first sub-circuit and the other end of the first giant magnetoresistive element of the second sub-circuit; and

wherein an end of one of the two of the second giant magnetoresistive elements is connected to an end of one of the two of the fourth giant magnetoresistive element to form a third sub-circuit;

an end of the other second giant magnetoresistive element is connected to an end of the other fourth giant magnetoresistive element to form an fourth sub-circuit;

a third potential is applied to the other end of the second giant magnetoresistive element of the third sub-circuit and the other end of the fourth giant magnetoresistive element of the fourth sub-circuit; and

a fourth potential different from the third potential is applied to the other end of the fourth giant magnetoresistive element of the third sub-circuit and the other end of the second giant magnetoresistive element of the fourth sub-circuit,

whereby the magnetic sensor is configured so as to generate an output in response to a GMR element output and a SAF element output, the GMR element output being a difference in potential between the junction where the first giant magnetoresistive element is connected to the third giant magnetoresistive element in the first sub-circuit and the junction where the first giant magnetoresistive element is connected to the third giant magnetoresistive element in the second sub-circuit, the SAF element output being the difference in potential between the junction where the second giant magnetoresistive element is connected to the fourth giant magnetoresistive element in the third sub-circuit and the junction where the second giant magnetoresistive element is connected to the fourth giant magnetoresistive element in the fourth sub-circuit.

8. The magnetic sensor according to claim 1, comprising a plurality of the first giant magnetoresistive elements and the same number of second giant magnetoresistive elements as the number of the first giant magnetoresistive elements;

wherein

the first giant magnetoresistive elements and the second giant magnetoresistive elements are disposed in parallel to each other and are alternately arranged with each other in a predetermined direction of the substrate;

the first giant magnetoresistive elements are connected in series to form a giant magnetoresistive element; and

the second giant magnetoresistive elements are connected in series to form another giant magnetoresistive element.

9. The magnetic sensor according to claim 1, comprising four of the first giant magnetoresistive elements and four of the second giant magnetoresistive elements;

wherein

two of the first giant magnetoresistive elements lie adjacent to each other to form a first group and the other two of the first giant magnetoresistive elements lie adjacent to each other to form a second group;

two of second giant magnetoresistive elements lie adjacent to each other to form a third group and the other two of the second giant magnetoresistive elements lie adjacent to each other to form a fourth group;

the first to fourth groups are arranged in parallel in a predetermined direction on the substrate in the order of;

the first group, the third group, the second group, and the fourth group, or the third group, the first group, the fourth group, and the second group, and wherein one of the first giant magnetoresistive elements of the first group is connected to one of the first giant magnetoresistive elements of the second group in series to form an element composed of first giant magnetoresistive elements, and the other first giant magnetoresistive element of the first group is connected to the other first giant magnetoresistive element of the second group in series to form an element composed of first giant magnetoresistive elements;

one of the second giant magnetoresistive elements of the third group is connected to one of the second giant magnetoresistive elements of the fourth group in series to form an element composed of second giant magnetoresistive elements, and the other second giant magnetoresistive element of the third group is connected to the other second giant magnetoresistive element of the fourth group in series to form an element composed of second giant magnetoresistive elements.