JP2009145074A - Flux gate sensor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve adjustment of sensitivity and a range during manufacturing a flux gate sensor without changing the form of a magnetic element. <P>SOLUTION: In a flux gate sensor comprising a thin film magnetic element 1 and a detection coil disposed around or neighboring the thin film magnetic element, and a wiring 2 for supplying current to the thin film magnetic element 1 in a predetermined direction, uniaxial magnetic anisotropy is induced to the thin film magnetic element 1 in a direction oblique to a direction perpendicular to an electrifying direction I of the element. The detection coil is preferably a thin film coil. Upon manufacturing a flux gate sensor, a step for adjusting sensitivity and a range is carried out by adjusting an angle θ of the uniaxial magnetic anisotropy with respect to the predetermined direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fluxgate sensor used as a high-sensitivity magnetic sensor in automobiles, mobile phones, and other various devices, and a method for manufacturing the same.

A fluxgate sensor is known as one of high-sensitivity magnetic sensors. Previous fluxgate sensors have a very large head length of 20 to 30 mm, and cannot be used in mobile phone devices that are strongly demanded for miniaturization. However, recently, a small flux gate sensor has been proposed (see Patent Documents 1 and 2).
Also, a flux gate sensor (see Non-Patent Document 1) in which a magnetic film and a thin film coil are laminated, and an orientation sensor and an electronic compass that apply the principle of an orthogonal flux gate sensor to a detection method of a magneto-impedance effect element (MI element) ( As shown in Non-Patent Documents 2 and 3, a fluxgate sensor that is very small is also sold.
Japanese Patent No. 2617498 JP 2006-201123 A “TMF-FG element [high-frequency driven fluxgate type]”, [online], Canon Electronics Inc., [November 2, 2007 search], Internet <URL: http: // www. canon-elec. co. jp / products / compo / tmf / feature / index-fg. html> “Direction Sensor Using MI Effect of Amorphous Material One-Chip Electronic Compass IC Overview and Usage”, [online], Aichi Micro Intelligent Co., Ltd., [searched November 2, 2007], Internet <URL: http // www. aichi-mi. com / 5_2_transistor_gijutu / transistor_gijutu. htm> “Development of electronic compass for mobile phone using MI sensor”, [online], Aichi Micro Intelligent Co., Ltd. [searched on November 2, 2007], Internet <URL: http: // www. aichi-mi. com / 5_4_MSJ / MSJ. HTM>

  A magnetic thin film or an amorphous wire serving as a magnetic core of a conventional fluxgate sensor has a domain wall 3 oriented substantially 90 ° with respect to the energization direction I as shown in FIG. The direction of the uniaxial magnetic anisotropy of the magnetic core was also oriented approximately 90 ° with respect to the energization direction (see FIG. 9 of Patent Document 2 and Non-Patent Documents 2 and 2). 3). In this case, if the sensor shape is determined, the sensitivity of the sensor and the magnetic field range (magnetic field range) are also determined. Therefore, if a sensor with a different magnetic characteristic specification is required, the sensor shape must be changed from the design. There was a problem.

  The present invention has been made in view of the above circumstances, and provides a fluxgate sensor that can be manufactured by adjusting sensitivity and range without changing the shape of a magnetic element, and a method for manufacturing the same. Is an issue.

In order to solve the above problems, the present invention provides a thin film magnetic element, a detection coil disposed around or in the vicinity of the thin film magnetic element, and a method for energizing the thin film magnetic element in a predetermined direction. A fluxgate sensor comprising a wiring, wherein the thin film magnetic element is provided with uniaxial magnetic anisotropy in a direction inclined from a direction perpendicular to the energizing direction of the element. To do.
In the fluxgate sensor of the present invention, it is preferable that the thin-film magnetic element is formed such that domain walls other than the domain wall generated by the reflux magnetic domain are inclined from a direction perpendicular to the energization direction of the element.
The detection coil is preferably a thin film coil.

  The present invention is also a method for manufacturing the above-described fluxgate sensor, including a step of adjusting sensitivity and range by adjusting an angle of uniaxial magnetic anisotropy with respect to the predetermined direction. Provided is a method of manufacturing a fluxgate sensor.

  According to the present invention, when manufacturing a fluxgate sensor, it is possible to adjust the sensitivity and range without changing the shape of the magnetic element, so that the design change of the sensor shape can be omitted and the cost can be reduced. It becomes possible to do.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 2 is a diagram schematically showing a magnetic domain structure when the thin film magnetic element in the fluxgate sensor of the present invention is not energized.

  The fluxgate sensor of the present embodiment includes a thin film magnetic element 1, a detection coil disposed around or in the vicinity of the thin film magnetic element, and a predetermined direction with respect to the thin film magnetic element 1 (hereinafter referred to as “energization direction”). And the thin film magnetic element 1 is provided with uniaxial magnetic anisotropy in a direction inclined from a direction perpendicular to the energizing direction I of the element. It is what. In the present invention, the direction of uniaxial magnetic anisotropy is the direction of the easy axis of magnetization.

  As the magnetic element of the fluxgate sensor, a linear, strip-shaped or rod-shaped magnetic body having conductivity can be used. In this embodiment, for example, a thin-film magnetic element having a shape such as a strip shape or a meander shape. 1 is preferred.

  In the fluxgate sensor of this embodiment, the wiring 2 is provided at both ends in the longitudinal direction of the thin film magnetic element 1 and is a drive power supply (not shown) for energizing the thin film magnetic element 1 in a predetermined direction. Connected to. That is, the energizing direction I for the thin film magnetic element 1 is the direction between the wires 2 (here, the longitudinal direction of the thin film magnetic element 1).

The detection coil (not shown) is arranged around or in the vicinity of the thin film magnetic element 1 and is used for taking out the sensor output. The detection coil is not particularly limited, and the same detection coil as that used in a conventional fluxgate sensor can be used.
When the detection coil is arranged around the thin film magnetic element 1, a coil formed by winding a conductive wire around the thin film magnetic element 1 can be used. In addition, the first conductor layer disposed on the upper layer from the thin film magnetic element 1, the second conductor layer disposed on the lower layer, one end of the first conductor layer, and the second conductor layer Around the thin film magnetic element 1, a through wiring connecting one end of the conductor layer and a through wiring connecting the other end of the first conductor layer and the other end of the second conductor layer are provided. Arranged coils may be formed.
When the detection coil is disposed in the vicinity of the thin film magnetic element 1, a thin film coil such as a spiral coil may be formed in a layer above or below the thin film magnetic element 1.

  Application of uniaxial magnetic anisotropy to the thin-film magnetic element 1 can be applied in any direction, for example, by performing heat treatment in a magnetic field. Examples of the method for heat treatment in a magnetic field include a method in which heat treatment in a static magnetic field is performed after heat treatment in a rotating magnetic field. Here, for the heat treatment in the rotating magnetic field, a method of performing, for example, 400 ° C., 3 kG, and 1 hour under a condition in which the sensor element is rotated can be employed. In addition, the heat treatment in the static magnetic field employs a method of performing, for example, 400 ° C., 3 kG, for 1 hour under a condition in which the static magnetic field application angle to the sensor element is fixed according to the direction of the uniaxial magnetic anisotropy to be applied. be able to.

  In the fluxgate sensor of this embodiment, the uniaxial magnetic anisotropy of the thin-film magnetic element 1 is given in a direction (tilt angle θ) inclined from a direction perpendicular to the energizing direction I of the element. As a result, the domain walls 3 other than the domain walls generated by the return magnetic domains are formed in a direction inclined from the direction perpendicular to the energization direction I of the element.

  The thin film magnetic element 1 has a higher sensitivity and a narrower range as the angle θ inclined from the direction perpendicular to the energizing direction is larger (approaching 90 °). Conversely, the smaller the angle θ (closer to 0 °), the lower the sensitivity but the wider the range. Here, the range is a magnetic field range in which the magnetic field-voltage characteristic is substantially a straight line, and this is a magnetic field range in which the fluxgate sensor can be used.

  Therefore, according to the fluxgate sensor of the present embodiment, the sensitivity and range can be adjusted by adjusting the angle θ inclined from the direction perpendicular to the energization direction at the time of manufacture. Thereby, it is possible to adjust the sensitivity and the range without changing the shape of the magnetic element, so that the design change of the sensor shape can be omitted, and the cost can be reduced.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited only to these Examples.

  A magnetic thin film as a thin film magnetic element, wiring connected to both ends of the magnetic thin film, and a detection coil comprising a thin film coil are formed to produce a fluxgate sensor, and the magnetic thin film is uniaxially magnetically anisotropic. When the magnetic property is imparted, the direction of uniaxial magnetic anisotropy (magnetization easy axis) is inclined from the direction perpendicular to the energizing direction to the thin film magnetic element (the angle θ is 70 °, 45 °, or 0 °). ) Heat treatment was performed in a magnetic field. Application of uniaxial magnetic anisotropy to a thin film magnetic element is performed after heat treatment in a rotating magnetic field at 400 ° C., 3 kG, 1 hour, for example, under the condition that the sensor element is rotated. Depending on the direction, the heat treatment was performed in a static magnetic field at 400 ° C., 3 kG for 1 hour under the condition that the static magnetic field application angle to the sensor element was fixed.

  In each case, while changing the magnitude of the external magnetic field, the magnitude of the induction output generated in the detection coil when the thin film magnetic element of the fluxgate sensor was energized was measured to obtain the magnetic field-voltage characteristics. As a result, the magnetic field-voltage characteristics shown in FIG. 3 and the sensitivity and range shown in Table 1 were obtained.

  As can be seen from these results, the thin film magnetic element 1 has a higher sensitivity and a narrower range as the angle θ inclined from the direction perpendicular to the energizing direction is larger. Conversely, the smaller the angle θ (closer to 0 °), the lower the sensitivity but the wider the range. By utilizing this characteristic, various sensors having different sensitivities and ranges can be manufactured by adjusting the angle θ using the same shape sensor, and the cost can be suppressed.

  The fluxgate sensor of the present invention can be used as a high-sensitivity magnetic sensor in automobiles, mobile phones, and other various devices.

It is a figure which shows typically the magnetic domain structure at the time of the no-energization of the thin film magnetic body element in the conventional fluxgate sensor. It is a figure which shows typically the magnetic domain structure at the time of the no-energization of the thin film magnetic body element in the fluxgate sensor of this invention. It is a graph explaining the Example of the fluxgate sensor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thin film magnetic body element, 2 ... Wiring, 3 ... Domain wall other than the domain wall which a return magnetic domain touches, I ... Current supply direction, M ... Spin direction, (theta) ... The angle of the direction inclined from the right angle with respect to the current supply direction.

Claims (4)

In a fluxgate sensor comprising a thin film magnetic element, a detection coil disposed around or in the vicinity of the thin film magnetic element, and a wiring for energizing the thin film magnetic element in a predetermined direction,
The thin film magnetic element is provided with a uniaxial magnetic anisotropy in a direction inclined from a direction perpendicular to the energizing direction of the element.   2. The fluxgate sensor according to claim 1, wherein the thin film magnetic element has a domain wall other than a domain wall generated by a reflux magnetic domain formed in a direction inclined from a direction perpendicular to the energization direction of the element.   The fluxgate sensor according to claim 1 or 2, wherein the detection coil is a thin film coil. A method for manufacturing the fluxgate sensor according to any one of claims 1 to 3,
A method of manufacturing a fluxgate sensor, comprising adjusting sensitivity and range by adjusting an angle of uniaxial magnetic anisotropy with respect to the predetermined direction.

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