JP4657836B2 - Magnetic thin film element using impedance element - Google Patents

Description

The present invention relates to a magnetic thin film element using an impedance element for detecting a weak magnetic field used in the fields of automobiles, home appliances, communication equipment, ships, aircraft, medical equipment and the like.

  A magnetic thin film element is formed by applying an external magnetic field to a magnetic thin film element having a magnetic domain structure, causing magnetization rotation, changing magnetic permeability due to domain wall movement, and applying a high-frequency current to a magnetic material. The magnetic sensor uses the property that the impedance of the material changes, and the magnetic sensor uses the property that the resistance value of the material changes due to the change of the magnetic domain by applying an external magnetic field.

  The present applicant has proposed an element in which impedance changes in the composition ratio of the Co-based material in the configuration of the magnetic layer and the conductor layer in Patent Document 1.

  Furthermore, Patent Document 2 proposes a magnetic bias means using a spiral coil, a thin film coil, and a magnetic film, with a resistance side made nonmagnetic and miniaturized.

  Patented is an element that is constructed by forming a high-permeability magnetic film on a non-magnetic substrate and has magnetic anisotropy so that the straight line is folded back several times in the middle to be perpendicular to the longitudinal direction. It is proposed in Document 3.

  In this way, the entire element can be shortened and miniaturized even if the total extension of the magnetic film is lengthened by turning back multiple times. Moreover, it becomes a high impedance and easy-to-use element.

  Patent Document 4 proposes a multilayer structure of a high permeability magnetic film.

  FIG. 10 is a plan view showing a conventional magnetic thin film element using the magneto-impedance effect. Referring to FIG. 10, the magnetic thin film element has five magnetic thin films 11, 12, 13, 14, 15 having a thickness of 2 μm and a length of 1 mm arranged in parallel, and ends of the magnetic thin films 11 and 12 are 0.6 μm. The conductor films 16 are connected, and the opposite ends of the magnetic thin films 12 and 13 are connected by the conductor film 16 as described above. Further, the opposite end is connected to the magnetic thin film 14 and connected in series up to the magnetic film 15, and the end of the magnetic film 11 corresponding to the series end and the end of the magnetic film 11 are connected to the electrode pad 17.

  In order to manufacture a magnetic thin film element utilizing the magneto-impedance effect shown in FIG. 10, a glass substrate 10 is exposed using a photoresist to create a resist mask of the element shape, and a magnetic film is formed by sputtering. . Thereafter, the magnetic film patterning is performed by a lift-off method to form a plurality of high-permeability magnetic thin films 11, 12, 13, 14, and 15 having an element shape. Further, resist masking of a conductor film that connects a plurality of magnetic films 11, 12, 13, 14, and 15 in series is created in the same process as described above, and the conductor films 16, 16, and 16 are patterned.

  Further, after patterning, heat treatment in a magnetic field is performed in a vacuum to remove the anisotropy during sputtering, and uniaxial anisotropy is applied in the width direction of the patterned magnetic films 11, 12, 13, 14, 15. It is a general manufacturing method.

  FIG. 11 is a perspective view showing the magnetic thin film of FIG. As shown in FIG. 11, the magnetic thin films 11, 12, 13, and 14 have a structure in which a nonmagnetic film 18 is sandwiched between a magnetic film 11a and a magnetic film 11b. In this conventional example, two magnetic films 11a are provided. A multilayer structure of four magnetic layers and three nonmagnetic layers, with two layers, two magnetic films 11b, and a nonmagnetic film 18 sandwiched between the layers.

  A high frequency probe is connected between the two electrode pads 17, a high frequency current of 10 MHz to 60 MHz is applied with a network analyzer, and an external magnetic field is applied in the longitudinal direction of the element to −1 KA / m to 1 KA / m to change the impedance. Observe.

  FIG. 12 is a diagram showing impedance characteristics of the conventional magnetic thin film element of FIG. As shown in FIG. 12, when the external magnetic field applied to the magnetic thin film element is applied from the negative side (-), the impedance change 101 is about the peak point on the positive side (+) of the external magnetic field, about 0.5 KA / m. Then, the change of impedance collapses. Conversely, when an external magnetic field is applied from the positive side (+), the impedance peak point (near -0.5 KA / m) on the negative side (−) of the external magnetic field is broken.

  FIG. 13 is a diagram for explaining the reason why the impedance of the conventional thin film element of FIG. 10 is broken. As shown in FIG. 13, there is a magnetic domain formation structure and magnetization movement at the end of the magnetic thin film element. An end portion where the magnetic thin film 11 and the magnetic thin film 12 are connected by the conductor film 6 is observed by a magnetic domain by the bitter method. The magnetic domain 102 formed at the end of the magnetic material has a rounded structure like a turtle shell, and the magnetic domain 103 remains even when an external magnetic field is applied above the saturation magnetic field. Further, when the applied magnetic field is demagnetized, the magnetic domain generation point is different from that at the time of application.

  As described above, the rod-shaped elongated magnetic thin film element is a part where the demagnetizing field becomes very strong because the end of the element is exposed to the air gap in a magnetic circuit manner. Since the demagnetizing field is weaker in the center of the element than in the end, it is relatively easy to induce anisotropy when the anisotropy is induced, and the magnetic domain is formed uniformly. However, since the demagnetizing field is strong, it is difficult to provide a uniform magnetic domain even when trying to induce anisotropy, and the magnetic domain structure often becomes complicated.

  In addition, because the magnetic thin film element end has a complicated magnetic domain structure, when a magnetic field is applied from the outside, the magnetic domain disappears or reappears from the same location when the magnetic domain occurs due to domain wall movement or magnetic domain rotation. There is a problem that causes hysteresis in the element characteristics.

Japanese Patent Laid-Open No. 10-90380 Japanese Patent Laid-Open No. 2002-6015 JP 2000-206217 A JP 2000-206216 A

Therefore, a technical problem of the present invention is to provide a magnetic thin film element using an impedance element with good reproducibility that does not generate hysteresis even when a magnetic field is applied from either a positive or negative external magnetic field.

According to the present invention, there is provided a magnetic thin film element including a plate-shaped magnetic thin film using at least one of Co group and Fe group having uniaxial anisotropy, wherein the magnetic thin film is at least at one end. A magnetic permeability transition start or completion unit is provided, and a magnetic field is applied to the magnetic thin film from the outside, thereby causing domain wall movement or magnetization rotation, and disappearance of magnetic domains and generation of magnetic domains from the start or completion of the magnetic permeability transition. Thus, a magnetic thin film element using an impedance element characterized in that the magnetic permeability of the magnetic thin film changes is obtained.

According to the present invention, in the magnetic thin film element using the impedance element, the magnetic permeability transition starts or ends at both ends of the magnetic thin film in a shape in which a plurality of the plate-like magnetic thin films are lined up. A magnetic thin film element using an impedance element having a completion portion is obtained.

According to the present invention, in the magnetic thin film element using the impedance element , the plate-like magnetic thin film has a shape in which a plurality of magnetic thin films are arranged in parallel, and the plurality of magnetic thin films are electrically connected in series. A magnetic thin film element using an impedance element having a structure in which adjacent end portions of the plurality of magnetic thin films are alternately connected to each other by a conductor film in the aligned direction. Is obtained.

Further, according to the present invention, in the thin film magnetic element using any one of the impedance elements, the permeability transition start or completion portion is within 20% of the element length from both ends of the plate-like magnetic thin film. Thus, a magnetic thin film element using an impedance element characterized by being provided at the position is obtained.

Further, according to the present invention, the in the magnetic thin film element using any one of the impedance elements, magnetic permeability transition started or completed part, impedance, characterized in that the micro-holes or is provided with a fine unevenness A magnetic thin film element using the element is obtained.

According to the present invention, in the magnetic thin film element using the impedance element, the permeability transition start or completion part has a minute uneven shape at the end made of the plate shape, and is sufficiently smaller than the element width. The magnetic thin film element using the impedance element is characterized in that the minute concavo-convex shape has one or a plurality of wedge-shaped mountain-shaped or valley-shaped structures.

Further, according to the present invention, in the magnetic thin film element using the impedance element, the permeability transition start or completion part has a minute hole in the end portion made of the plate shape, and is a hole sufficiently smaller than the element width. Thus, a magnetic thin film element using an impedance element characterized by having a structure having one or a plurality of can be obtained.

According to the present invention, in the magnetic thin film element using the impedance element, the magnetic thin film has a multilayer structure in which a magnetic thin film base and a nonmagnetic thin film base are stacked . The magnetic thin film element can be obtained.

According to the present invention, in the magnetic thin film element using the impedance element, the width of the magnetic thin film element is 5 μm to 1000 μm, and the sharp concavo-convex shape at the end of the element is a wedge having an angle of 100 ° or less. A magnetic thin film element using an impedance element characterized by being shaped can be obtained.

Further, according to the present invention, in the magnetic thin film element using the impedance element, the width of one element is 5 μm to 1000 μm, and the diameter of the minute hole at the end of the element is 50% or less of the element width. A magnetic thin film element using an impedance element having a certain characteristic can be obtained.

According to the present invention, the element end of the magnetic thin film element has a structure with a pointed or uneven shape or a minute hole shape, so that it can be applied from either a positive magnetic field or a negative magnetic field of an external magnetic field. It is possible to provide a magnetic thin film element using an impedance element having good reproducibility and no hysteresis in the permeability change.

The magnetic thin film element using the impedance element according to the embodiment of the present invention will be described below.

  The magnetic thin film element of the present invention applies a high-frequency current as a carrier to a magnetic material, and the skin depth of the skin effect generated in the magnetic material by the high-frequency carrier current changes with respect to an external magnetic field, thereby This is a magnetic thin film element using an impedance element utilizing an effect of changing impedance (MI effect).

  In addition, the magnetic thin film element of the present invention is a magnetic thin film element having an effect of changing the resistance value (MR effect) by applying a constant current to the magnetic material, and rotating the magnetization of the magnetic material by the magnetic field strength from the outside. In addition, an element having a structure having a transmission magnetic permeability transition start or completion portion having a sharp concavo-convex shape or a minute circular hole shape at both ends of a plate-like magnetic thin film including a cube is provided. Here, in the present invention, the part related to the effect (MR effect) in which the resistance value changes due to the magnetic field strength from the outside due to the magnetization rotation of the magnetic material is referred to as a permeability transition start or completion part.

  In the magnetic thin film element of the present invention, the width of the element 1 is 5 μm to 1000 μm, and the sharp concavo-convex shape at the end of the element has a wedge shape with an angle of 100 ° or less.

  In the magnetic thin film element according to the present invention, the width of one element is 5 μm to 1000 μm, and the minute hole diameter at the end of the element has minute holes of 50% or less of the width.

  In the magnetic thin film element of the present invention, the structure of the element may be a single plate-shaped magnetic thin film, or may have a multilayer structure including a laminated magnetic film and a nonmagnetic film. good.

  Now, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a magnetic thin film of a magnetic thin film element according to a first embodiment of the present invention. Referring to FIG. 1, wedge-shaped notched shapes 1a and 1b (opening angle 60 °) are provided at both ends in the longitudinal direction of a plate-like magnetic thin film element.

  In FIG. 2, five magnetic thin films 11, 12, 13, 14, and 15 are arranged in parallel in the same manner as in the embodiment by using a photomask and performing a series of operations such as exposure, development, and magnetic film sputtering. The magnetic films are connected in series at the conductor film 16. The thickness, length, and conductor film thickness of the magnetic thin film are the same as in the conventional example.

  FIG. 3 is an enlarged plan view of FIG. Sharp wedge-shaped notch shapes 1a, 1b, 1c, 1d, and 1e were provided at both ends of each element as the start or completion of permeability transition. The shape is created for the purpose of forming a nucleus for generating a magnetic domain, and the generation and disappearance of a magnetic domain when an external magnetic field is applied is always performed from the nucleus. In the present invention, the point having such a nucleus is called a permeability transition start or completion part. By providing this permeability transition start or completion part, the hysteresis is improved.

  FIG. 4 is a diagram showing impedance characteristics measured in the shape according to the first embodiment of the present invention. As shown in FIG. 4, the impedance change 26 when the external magnetic field applied to the element is applied from the negative side (-) and the impedance change 25 when the external magnetic field is applied from the positive side (+) have substantially the same locus. Tracing.

  FIG. 5 is a photograph of the magnetic thin film according to the first embodiment of the present invention observed in the magnetic domain by the bitter method at the end of the element as in the prior art. Referring to FIG. 5, before applying an external magnetic field, a fine domain wall is not observed, and by applying an external magnetic field, the magnetization is generated in the nucleation site of the element according to the present invention. It has been observed to magnetize towards. On the other hand, when the external magnetic field is reversed, it is observed that the magnetization is magnetized toward the nucleation site of the element. In the present invention, a point having a nucleation site is called a permeability transition start or completion part. In the present invention, by providing this magnetic permeability transition start or completion portion, the hysteresis of the magnetic permeability of the element is improved, and a reproducible characteristic that is not affected by the application direction of the external magnetic field is obtained.

  FIG. 6 is a perspective view showing a magnetic thin film according to the second embodiment of the present invention. Referring to FIG. 6, a structure is provided in which round hole shapes 2 a and 2 b (hole diameter: 10 μm) are provided in the vicinity of the end of the thin film of the magnetic thin film element as magnetic permeability transition start or completion.

  Next, FIG. 7 shows that the magnetic thin films 11, 12, 13, 14, and 15 prepared by the photomask are arranged in parallel, and at the end of the magnetic film of the element in which the magnetic films are connected in series by the conductor film 16. This is a prototype with round hole-shaped structures 2a, 2b, 2c, 2d and 2e. FIG. 8 is a partially enlarged view of FIG.

  Similarly to the first embodiment, the thin film magnetic element according to the second embodiment of the present invention can improve the hysteresis of the magnetic permeability of the element and obtain reproducible characteristics that are not affected by the application direction of the external magnetic field. .

  FIG. 9 is a perspective view showing a magnetic thin film according to the third embodiment of the present invention. Referring to FIG. 9, photomasks having sharp pointed shapes 3 a and 3 b were formed at both end portions of the magnetic thin film as magnetic permeability transition start or completion portions. Similar to the first and second embodiments, the shape is produced for the purpose of forming a nucleation site for generating a magnetic domain, and the occurrence and disappearance of a magnetic domain when an external magnetic field is applied is always observed. By being performed from the nucleus, a point having such a portion is called a magnetic permeability transition start or completion portion, and the hysteresis is improved by providing the magnetic permeability transition start or completion portion.

  The thin film magnetic element according to the third embodiment of the present invention also improves the hysteresis of the magnetic permeability of the element by providing a magnetic permeability transition start or completion portion at the end as in the first and second embodiments. In addition, reproducible characteristics that are not affected by the direction in which the external magnetic field is applied can be obtained.

  As described above, the thin film magnetic element of the present invention is optimal for a magnetic thin film element for detecting a weak magnetic field used in the fields of automobiles, home appliances, communication equipment, ships, aircraft, medical equipment and the like.

It is explanatory drawing (the permeability start or completion part is a pointed concave shape) of the edge part shape of the magnetic thin film element by the 1st Embodiment of this invention. FIG. 3 is a partial plan view showing the end portion of the magnetic thin film element according to the first embodiment of the present invention (the magnetic permeability start or completion portion has a pointed concave shape). It is the elements on larger scale of the magnetic thin film element edge part of FIG. 2 (The permeability start or completion part is pointed concave shape). It is explanatory drawing of the impedance change with respect to the external magnetic field of the magnetic thin film element by the 1st Embodiment of this invention. It is a photograph for demonstrating the magnetic domain change in the external magnetic field application of the metal structure of the magnetic thin film element edge part of the 1st Embodiment of this invention. It is a perspective view which shows the edge part shape of the magnetic thin film element by the 2nd Embodiment of this invention (The permeability start or completion part is a microhole shape). FIG. 6 is a partial plan view of an end portion of a magnetic thin film element according to a second embodiment of the present invention (permeability start or completion portion is a minute hole shape). It is the elements on larger scale of the magnetic thin film element edge part of FIG. 7 (The permeability start or completion part is a microhole shape). It is explanatory drawing (the magnetic permeability start or completion part is a pointed convex shape) of the edge part shape of the magnetic thin film element by the 3rd Embodiment of this invention. It is explanatory drawing of the patterning shape of the magnetic thin film element by a prior art. It is explanatory drawing of the edge part of the conventional magnetic thin film element. It is explanatory drawing of the impedance change with respect to the external magnetic field of the conventional magnetic thin film element. It is a photograph for demonstrating the magnetic domain change in the external magnetic field application of the conventional magnetic thin film element edge part.

1a, 1b, 1c, 1d, 1e Concave-shaped structure with pointed end of element (permeability start or completion part)
2a, 2b, 2c, 2d, 2e Micro hole shape structure at element end (permeability start or completion part)
3a, 3b Convex-shaped structure with sharp element end (permeability start or completion)
DESCRIPTION OF SYMBOLS 10 Glass substrate 11, 12, 13, 14, 15 Magnetic thin film element 11a Magnetic thin film (upper layer)
11b Magnetic thin film (lower layer)
16 Conductor film (series connection, conductor film (terminal-pad)
18 Nonmagnetic interlayer 25 External magnetic field-impedance characteristics (positive magnetic field → negative magnetic field)
26 External magnetic field-impedance characteristics (negative magnetic field → positive magnetic field)
27 Magnetic domain structure of magnetic thin film element end before application of external magnetic field (present invention)
28 Magnetic domain structure of magnetic thin film element end after application of external magnetic field (present invention)
100 External magnetic field-impedance characteristics (positive magnetic field → negative magnetic field)
101 External magnetic field-impedance characteristics (negative magnetic field → positive magnetic field)
102 Magnetic domain structure of magnetic thin film element end before applying external magnetic field (conventional)
103 Magnetic domain structure of magnetic thin film element end after application of external magnetic field (conventional)

Claims (10)

A magnetic thin film element comprising a plate-shaped magnetic thin film using at least one of a Co-based alloy and a Fe-based alloy having uniaxial anisotropy, wherein the magnetic thin film has a magnetic permeability at least at one end. A transition start or completion part is provided, and by applying a magnetic field to the magnetic thin film from the outside, domain wall movement or magnetization rotation occurs, the disappearance of the magnetic domain, the generation of the magnetic domain occurs from the permeability transition start or completion part, A magnetic thin film element using an impedance element, wherein magnetic permeability of the magnetic thin film changes. The magnetic thin film element using the impedance element according to claim 1, wherein a plurality of the plate-like magnetic thin films are arranged so as to be folded back, and the permeability transition start or completion portion is provided at both ends of the magnetic thin film. A magnetic thin film element using an impedance element , characterized by comprising: The magnetic thin film element using the impedance element according to claim 1, wherein the plate-shaped magnetic thin film has a shape in which a plurality of magnetic thin films are arranged in parallel, and further electrically connects the plurality of magnetic thin films in series. Therefore, a magnetic thin film element using an impedance element having a structure in which adjacent end portions of the plurality of magnetic thin films are alternately connected in a lined direction by a conductor film. 4. The magnetic thin film element using the impedance element according to claim 1, wherein the magnetic permeability transition start or completion portion is 20 times the element length from both ends of the plate-like magnetic thin film. A magnetic thin film element using an impedance element, wherein the magnetic thin film element is provided at a position within%. The magnetic thin film element using the impedance element according to any one of claims 1 to 3, wherein the permeability transition start or completion portion has a minute hole or a minute uneven shape. Magnetic thin film element using impedance element . The magnetic thin film element using the impedance element according to claim 5, wherein the magnetic permeability transition start or completion part has a minute uneven shape at an end formed of the plate shape, and has a shape sufficiently smaller than the element width. 2. The magnetic thin film element using an impedance element, wherein the minute concavo-convex shape has one or a plurality of wedge-shaped mountain-shaped or valley-shaped structures. 6. The magnetic thin film element using the impedance element according to claim 5, wherein the permeability transition start or completion part has a minute hole at the end made of the plate shape, and one hole sufficiently smaller than the element width. Alternatively, a magnetic thin film element using an impedance element having a plurality of structures. In the magnetic thin film element using an impedance element according to claim 1, wherein the magnetic thin film, magnetic thin film and a magnetic thin film base and a non-magnetic thin film base using an impedance element characterized by having a multilayer structure that is laminated element. 7. The magnetic thin film element using the impedance element according to claim 6, wherein the width of the magnetic thin film element is 5 μm to 1000 μm, and the sharp concavo-convex shape at the end of the element has a wedge shape with an angle of 100 ° or less. A magnetic thin film element using an impedance element. The magnetic thin film element using the impedance element according to claim 7, wherein the width of one element is 5 μm to 1000 μm, and the diameter of the minute hole at the end of the element is 50% or less of the element width. A magnetic thin film element using a characteristic impedance element.