Magnetic sensor

Abstract

To provide a magnetic sensor capable of detecting a weak magnetic field.SOLUTION: A magnetic sensor according to the present invention comprises: a magneto-resistive element 10 that has a multilayer film in which a first magnetic layer 102, a non-magnetic layer 103 and a second magnetic layer 104 are sequentially laminated, and which includes a plurality of lateral vanes 10a, 10c provided on in-plane side edges in a direction (second direction) in-plane orthogonal to an energization pivot part 10b and the energization direction (first direction) of the energization pivot part 10b, and which are separated by an insulating or high-resistance region along the energization direction; and a pair of magnetic flux convergence magnetic substance layers 11a, 11b that are respectively arranged on both sides of the energization pivot part 10b along an in-plane orthogonal direction (second direction), the magnetic flux convergence magnetic substance layers 11a, 11b having regions that overlap the lateral vanes 10a, 10c in the film thickness direction of the magneto-resistive element 10 (third direction orthogonal to the first and second directions).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic sensor. [Background technology]

[0002] As highly sensitive magnetic sensors capable of detecting ultra-small magnetic fields of the picotesla (pT) order, TMR and GMR sensors that utilize MFCs (Magnetic Flux Concentrators) that converge and concentrate the detected magnetic field onto a magnetoresistive element have attracted attention. A configuration has been proposed in which a portion of a giant magnetoresistance (GMR) element is overlapped on an MFC to efficiently converge the magnetic flux of the MFC onto the GMR portion on both sides of the GMR element (see Patent Document 1). A magnetoencephalograph using such a magnetic sensor is proposed in Patent Document 2. Furthermore, an MFC is disclosed, for example, in Patent Document 3.

[0003] The overlapping portion of the GMR element and MFC has an insulating layer sandwiched between them, and sense current is passed only through the GMR portion. The GMR element is rectangular, and the current is distributed uniformly across the width of the GMR element. Therefore, a uniform resistance change occurs at any point across the width of the GMR. As a result, the sensitivity distribution is uniform within the GMR width. On the other hand, in the overlapping portion, the signal magnetic flux is concentrated in the MFC portion rather than the GMR, and the inflow of the signal magnetic flux into the overlapping portion GMR is small and does not contribute to magnetic field detection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2019 / 239933 paragraph 0009, claim 4 [Patent Document 2] Japanese Patent Application Publication No. 2018-48832 [Patent Document 3] U.S. Patent No. 7,358,724 Summary of the Invention [Problem to be solved by the invention]

[0005] In the magnetic sensor disclosed in Patent Document 1, the MFC gap (corresponding to the GMR region without the overlapping portion) can be made narrower than the GMR width, allowing the signal magnetic flux to be efficiently converged and increased in the GMR region of the MFC gap. However, GMR current also flows in the overlapping portion, where the signal magnetic field hardly passes. Therefore, if the overlapping portion is made wider than the gap portion to efficiently converge the magnetic flux in the GMR portion, the current in the GMR sensitive region in the MFC gap decreases due to the dispersion of the GMR current flowing in the overlapping portion, resulting in a problem of a decrease in the output voltage (resistance change x current) due to resistance change. This problem must be overcome in applications that require the detection of extremely weak magnetic fields, such as magnetoencephalography. An object of the present invention is to provide a magnetic sensor capable of detecting a very weak magnetic field, such as that used in a magnetoencephalograph. [Means for solving the problem]

[0006] [1] As shown in Figures 1 and 2, the magnetic sensor of the present invention includes a magnetoresistive element 10 having a multilayer film in which a first magnetic layer 102, a non-magnetic layer 103, and a second magnetic layer 104 are sequentially stacked, the magnetoresistive element 10 including a current-carrying pivot portion 10b and a plurality of side wing portions 10a, 10c provided on the inner edge of the current-carrying pivot portion 10b in a direction (second direction) perpendicular to the current-carrying direction (first direction) and separated by insulating or high-resistance regions along the current-carrying direction; A pair of flux convergence magnetic layers 11a, 11b are arranged on both sides of the current-carrying pivot portion 10b along a direction (second direction) perpendicular to the plane of the current-carrying pivot portion 10b, and the flux convergence magnetic layers 11a, 11b have portions that overlap with the lateral wing portions 10a, 10c in the film thickness direction of the magnetoresistive element 10 (third direction perpendicular to the first and second directions).

[0007] In the device configured in this manner, the area of ​​the magnetoresistive element overlapping with the flux convergence magnetic layers 11 a, 11 b is limited to the lateral wings 10 a, 10 c, and the current-carrying pivot 10 b is positioned within the gap g between the flux convergence magnetic layers 11 a, 11 b, thereby reducing current leakage to the overlapping area and concentrating current only in the current-carrying pivot 10 b. As a result, the adverse effect of the magnetoresistive effect being reduced by the area of ​​the magnetoresistive element overlapping with the flux convergence magnetic layers 11 a, 11 b is suppressed, and the magnetic signal detection sensitivity of the magnetic sensor is improved.

[0008] [2] In the magnetic sensor [1] of the present invention, it is preferable that the side wing portions 10a and 10c have an area that does not overlap with the current-carrying pivot portion 10b. [3] In the magnetic sensor [2] of the present invention, preferably, the shape of the side wing portions 10a, 10c is such that, when the connection width of the side wing portions 10a, 10c with the current-carrying pivot portion 10b is Lf and the interval between the adjacent side wing portions 10a, 10c is Lg, Lg <Lf It is preferable that the shape satisfies the following relation:

[0009] [4] In the magnetic sensors [1] to [3] of the present invention, preferably, the shape of the current-carrying pivot portion 10b and the side wing portions 10a, 10c is such that, when the width of the current-carrying pivot portion 10b is W, the connection width of the side wing portions 10a, 10c with the current-carrying pivot portion 10b is Lf, and the extension length of the side wing portions 10a, 10c is Wf, W>Lf and Wf>Lf It is preferable that the shape satisfies the following relation: [5] In any of the magnetic sensors [1] to [4] of the present invention, preferably, when the width of the current-carrying pivot portion 10b is W and the extension length of the side wing portions 10a and 10c is Wf, W <Wf It is preferable that the shape satisfies the following relation:

[0010] [6] In any of the magnetic sensors [1] to [5] of the present invention, the interface between the flux convergence magnetic layers 11a, 11b and the magnetoresistive element 10 is preferably separated by an insulating or high-resistance region. [7] In any of the magnetic sensors [1] to [5] of the present invention, as shown in FIG. 9, the flux convergence magnetic layers 911a and 911b and the magnetoresistive element 910 are preferably in contact with each other in the film thickness direction. [8] In the magnetic sensor [7] of the present invention, preferably, when the spacing between the pairs of magnetic flux convergence magnetic layers 911 a, 911 b provided on either side of the current-carrying direction of the current-carrying pivot portion 910 b is g, the width of the current-carrying pivot portion 910 b is W, and the connection width of the side wing portions 910 a, 910 c to the current-carrying pivot portion 910 b is Lf, W+2Lf≦g and Wf>Lf It is preferable that the shape satisfies the following relation: [9] In any of the magnetic sensors [1] to [8] of the present invention, it is preferable to further include a wiring layer 16 for AC current supply, which is arranged so as to overlap the current-carrying pivot portion 10b in the film thickness direction, as shown in, for example, FIG. 11. [Effects of the Invention]

[0011] According to the magnetic sensor of the present invention, a magnetic flux convergence magnetic layer is provided in the film thickness direction of the magnetoresistive element, overlapping with the side wing portion but not overlapping with the current-carrying pivot portion. Therefore, the GMR current flowing through the current-carrying pivot portion is not dispersed in the area where the magnetoresistive element and the side wing portion overlap, and weak magnetic fields can be detected. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a plan view of the magnetic sensor according to the first embodiment of the present invention, showing the case where the left and right lateral extensions have elliptical shapes at their tip portions. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA shown in FIG. [Figure 3] FIG. 10 is a plan view of a magnetic sensor showing a first modified embodiment of the present invention, showing a case where the phases of repetition along the first direction of the left and right lateral extension portions are different. [Figure 4] FIG. 10 is a plan view of a magnetic sensor showing a second modified embodiment of the present invention, showing a case where the left and right lateral extension portions have a rectangular shape. [Figure 5]This is a plan view of a magnetic sensor showing a third modified embodiment of the present invention, in which the shape of the left and right lateral extension portions is elliptical at the tip, and the width is wider in the region between the tip and the connection end with the central shaft portion than at the connection end with the central shaft portion. [Figure 6] 10 is a diagram showing an example of calculation of the current distribution in the magnetoresistance element, and also shows the relationship between the distance in the second direction from the center of the magnetic sensing element current-carrying pivot 10b and the current. [Figure 7] 10 is a diagram showing the relationship between the distance in the second direction from the center of the magnetic sensing element current-carrying pivot portion 10b and the current, with Lf as a parameter. FIG. [Figure 8] 6A is a diagram showing the relationship between the ratio Iwf / Iw of the current Iw in the side wing portion 10a region of the magnetic sensing element to the leakage current Iwf and Lf / W, and FIG. 6B is a diagram showing the relationship between Iwf / Iw, which is the ratio of the leakage current Iwf to the side wing region current Iw of the magnetic sensing element obtained from FIG. 6, and Lg / Lf. [Figure 9] 10A shows a second embodiment of the present invention, in which (A) is a plan view in the first and second directions, and (B) is a cross-sectional view of a portion BB in the third and second directions. [Figure 10] 10A and 10B are plan views showing a third embodiment of the present invention, taken along a first direction and a second direction. [Figure 11] 10A and 10B are cross-sectional views of the portion AA in the third direction and the second direction, showing the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment will be described with reference to the drawings. [Example]

[0014] (First Example) A magnetic sensor according to a first embodiment will be described with reference to Figs. 1 and 2. Fig. 1 is a plan view of a magnetic sensor unit according to a first embodiment of the present invention, showing a case in which the left and right lateral extensions have elliptical shapes at their tips. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Note that Fig. 1 is a plan view looking upward from the cross section taken along line BB in Fig. 2. In the figure, the magnetic sensor according to the first embodiment includes a magnetoresistive element film 10, a magnetic layer 11, a substrate 12, and an insulating layer, to which a constant current source 20 and a signal voltage detection unit 22 are connected. Note that the insulating layers are not shown in Fig. 1, but are shown as insulating layers 15a and 15b in Fig. 2.

[0015] The magnetoresistive element film 10 is composed of a magnetic sensing element current-carrying pivot part 10b and magnetic sensing element side wing parts 10a and 10c in the planar direction, and a base layer 101, a pinned layer 102, an intermediate layer 103, a free layer 104, and a cap layer 105 stacked in the film thickness direction on a substrate 12. The substrate 12 may be a silicon substrate, a GaAs substrate, an alumina substrate, a glass substrate, or the like. Regarding the coordinate system, the first direction is the longitudinal direction of the magnetic sensing element current-carrying pivot part 10b, which is the GMR current-carrying direction. The second direction is the width direction of the magnetic sensing element current-carrying pivot part 10b, which is also the longitudinal direction of the magnetic sensing element side wing parts 10a, 10c. The third direction is the film thickness direction of the magnetoresistive element film 10.

[0016] The magnetic sensing element current-carrying pivot 10b is the functional center of the magnetic sensor, and has electrodes connected to a constant current source 20 at both ends in the first direction. By making the longitudinal length of the magnetic sensing element current-carrying pivot 10b sufficiently longer (for example, 10 times longer) than the width of the magnetic sensing element current-carrying pivot 10b, the magnetization of the free layer 104 is also stabilized in the longitudinal direction in the absence of a detection magnetic field. When the pinned layer magnetization is fixed in width and direction, the resistance of the magnetic sensor changes linearly when a detection magnetic field is applied. A voltage change corresponding to this resistance change can be detected. The magnetic sensing element side wings 10a, 10c are portions of the magnetoresistance element 10 that extend from the second direction end of the magnetic sensing element current-carrying pivot part 10b, with the magnetic sensing element side wing part 10a extending in the + direction of the second direction (upward in Fig. 1) and the magnetic sensing element side wing part 10c extending in the - direction of the second direction (downward in Fig. 1). A plurality of the magnetic sensing element side wings 10a, 10c are provided along the first direction, sandwiching an insulating region 15 therebetween.

[0017] Lf is the length of the portion where the magnetic sensing element lateral wing portion 10a contacts the magnetic sensing element current-carrying pivot portion 10b. Lg is the distance between adjacent magnetic sensing element lateral wing portions 10a, 10c of the magnetic sensing element lateral wing portions 10a, 10c. Wf is the extension length from the connection portion of the magnetic sensing element lateral wing portions 10a, 10c with the magnetic sensing element current-carrying pivot portion 10b to the extension end point. W is the width of the magnetic sensing element current-carrying pivot portion. In the embodiment shown in Figure 1, the length of the portion where the magnetic sensing element lateral wing portion 10c contacts the magnetic sensing element lateral wing portion 10c is also Lf, but the Lf of the magnetic sensing element lateral wing portion 10a and the magnetic sensing element lateral wing portion 10c may be different.

[0018] 2, the magnetoresistive element 10 is made up of a plurality of laminated bodies arranged along a third direction, which is orthogonal to the first and second directions and corresponds to the film thickness direction. The underlayer 101 is a layer formed on the substrate 12 and is used to improve the crystallinity of the pinned layer 102 (increasing the crystal grain size and aligning the crystals perpendicular to the film surface), and is made of, for example, Ta, Ru, Cu, Ni, Fe, or Cr. The pinned layer 102 is a layer with fixed magnetization, and is, for example, a laminate of an antiferromagnetic film such as IrMn, CoFe, Ru, and CoFe. It is known that sufficient magnetization fixation of the pinned layer 102 can be achieved by laminating an antiferromagnetic film such as IrMn on the side opposite the intermediate layer 103, and further sandwiching a Ru layer or the like that generates antiferromagnetic interlayer coupling between the two layers. It is preferable to use a CoFe alloy or the like for the pinned layer 102, which is suitable for exhibiting the magnetoresistance effect. The intermediate layer 103 is a non-magnetic intermediate layer provided between the pinned layer 102 and the free layer 104, and is made of Cu or the like that is suitable for producing the magnetoresistance effect. The free layer 104 is a layer whose magnetization rotates in response to a signal magnetic field, and uses a CoFe alloy, a NiFe alloy, a CoFeNi alloy, a laminated structure of CoFe and NiFe, or the like. The cap layer 105 is deposited so as to cover the free layer 104, and is made of, for example, Ta or Ru.

[0019] A pair of MFC magnetic layers 11a and 11b are disposed on the magnetoresistive element 10 along the third direction, sandwiching an insulating layer 15b. The pair of MFC magnetic layers 11a and 11b are soft magnetic films made of NiFe, NiFeMoCu, an amorphous alloy, or the like, and form part of a magnetic flux concentrator (MFC). g is the gap between the pair of MFC magnetic layers 11a and 11b along the second direction, and is preferably greater than the width W of the magnetic sensing element current-carrying pivot portion. The pair of MFC magnetic layers 11a and 11b overlap with the magnetic sensing element side wing portions 10a and 10c of the magnetoresistive element 10 along the film thickness direction, sandwiching the insulating layer 15b. In the magnetic flux concentrator magnetic circuit, a magnetic circuit (not shown), as disclosed in Patent Document 3, is provided near the pair of MFC magnetic layers 11a and 11b. In the magnetic sensing element side wing portions 10a, 10c, there is provided an overlapping region with the MFC magnetic layers 11a, 11b and the insulating layer 15b sandwiched therebetween. The provision of this overlapping region increases the convergence efficiency of the signal magnetic field from the MFC magnetic layers 11a, 11b to the magnetic sensing element current-carrying pivot portion 10b, thereby increasing detection sensitivity.

[0020] The insulating layer 15b is provided between the MFC magnetic layers 11a and 11b and the magnetic sensing element side wing portions 10a and 10c and magnetic sensing element current-carrying pivot portion 10b, and is made of SiO2, Al2O3, etc. Its thickness is the minimum necessary to ensure stable insulation. The insulating layer 15a is provided to cover the MFC magnetic layers 11a and 11b. The constant current source 20 is connected to the electrodes provided on both ends of the magnetic sensing element current-carrying pivot 10b, and causes a current to flow in a first direction through the magnetic sensing element current-carrying pivot 10b. The signal voltage detection unit 22 is connected to the electrode portions provided at both ends of the magnetic sensing element current-carrying pivot portion 10b, and by detecting the voltage generated in the magnetoresistance element 10, detects that the resistance of the magnetoresistance element 10 changes in response to the signal magnetic field applied in the second direction of the magnetoresistance element 10.

[0021] In the device configured in this manner, current flows in a first direction through the magnetic sensing element current-carrying pivot 10b when power is supplied from the constant current source 20. When the resistance of the magnetoresistive element 10 changes in response to a signal magnetic field applied in a second direction perpendicular to the first direction, the voltage of the magnetoresistive element 10 changes. The signal magnetic field is measured by detecting this change with the signal voltage detection unit 22. It is preferable to use the four magnetic sensor units shown in FIG. 1 to configure a Wheatstone bridge as described in Patent Documents 1 and 2 to form a magnetic sensor.

[0022] 3 is a plan view of a magnetic sensor showing a first modified embodiment of the present invention, showing a case where the repetition phases of the left and right lateral extension portions along the first direction are different. In the first modified embodiment, the magnetoresistive element film is composed of a magnetic sensing element current-carrying pivot portion 310b and magnetic sensing element side wing portions 310a and 310c. The magnetic sensing element side wing portion 310a and the magnetic sensing element side wing portion 310c have different repetition phases along the first direction.

[0023] 4 is a plan view of a magnetic sensor according to a second modified embodiment of the present invention, showing a case in which the left and right lateral extensions are rectangular. In this second modified embodiment, the magnetoresistive element film is made up of a magnetic sensing element current-carrying pivot portion 410b and magnetic sensing element side wing portions 410a and 410c. In the embodiment shown in FIG. 1, the tip of the magnetic sensing element side wing portion 10a is roughly elliptical, but the tip of the magnetic sensing element side wing portions 410a and 410c may also be rectangular, as shown in FIG.

[0024] 5 is a plan view of a magnetic sensor showing a third modified embodiment of the present invention, in which the left and right lateral extensions are elliptical at their tips and wider in the region between the tips and the connection end with the central shaft than at the connection end with the central shaft. In the third modified embodiment, the magnetoresistive element film is composed of a magnetic sensing element current-carrying pivot 510b and magnetic sensing element side wing portions 510a and 510c. As shown in FIG. 5, the magnetic sensing element side wing portions 510a and 510c may have a thickened region at a position away from the boundary with the magnetic sensing element current-carrying pivot 510b that is slightly wider than the connection width Lf of the magnetic sensing element side wing portions with the magnetic sensing element current-carrying pivot portion.

[0025] Figure 6 shows an example of the calculated current distribution in the magnetic resistance element 10, and also shows the relationship between the distance in the second direction from the center of the magnetic sensing element current-carrying pivot 10b and the current. The current distribution in the magnetic sensing element current-carrying pivot 10b and the magnetic sensing element side wing portions 10a and 10c was calculated assuming the current in the magnetic resistance element 10 is uniform in the thickness direction. As shown in Figure 1, the magnetic sensing element side wing portions 10a and 10c have the same shape. The width of the magnetic sensing element current-carrying pivot 10b was W = 5 μm, the connection width of the magnetic sensing element side wing portion with the magnetic sensing element current-carrying pivot Lf = 0.5 μm, and the spacing between adjacent magnetic sensing element side wing portions Lg = 0.05 μm. The extension length Wf of the magnetic sensing element side wing portions was set to three conditions: 1, 3, and 10 μm. In the figure, the - direction indicates the side of the magnetic sensing element's lateral wing portion 10c, and the + direction indicates the side of the magnetic sensing element's lateral wing portion 10a. Even if the extension length Wf of the magnetic sensing element's lateral wing portion is changed to 1, 3, or 10 μm, the leakage current distribution to the magnetic sensing element's lateral wing portions 10a and 10c remains the same (all overlap), and is limited to an area approximately 0.5 μm away from the boundary of the magnetic sensing element's lateral wing portion 10a. This limited area roughly coincides with the connection width Lf of the magnetic sensing element's lateral wing portion with the magnetic sensing element's current-carrying pivot portion. No current flows in areas more than 0.5 μm away.

[0026] Figure 7 shows the relationship between the second direction distance from the center of the magnetic sensing element current-carrying pivot 10b and the current, with the connection width Lf of the magnetic sensing element side wing portion and the magnetic sensing element current-carrying pivot portion as a parameter. The width W of the magnetic sensing element current-carrying pivot 10b is 5 μm, the extension length Wf of the magnetic sensing element side wing portion is 5 μm, and the spacing Lg between adjacent magnetic sensing element side wing portions is 0.05 μm. As the connection width Lf increases, the leakage current into the magnetic sensing element side wing portions 10a and 10c increases.

[0027] FIG. 8(A) shows the relationship between Iwf / Iw, which is the ratio of the current Iw to the leakage current Iwf in the magnetic sensing element side wing portion 10a, and Lf / W, which is the ratio of the connection width Lf to the width W of the magnetic sensing element current-carrying pivot portion. The amount of leakage current increases in proportion to Lf / W. Making the connection width Lf sufficiently small relative to the width W of the magnetic sensing element current-carrying pivot portion is effective in confining the current to the magnetic sensing element current-carrying pivot portion 10b. Setting Lf / W to 0.1 suppresses the leakage current to about 5%.

[0028] 8(B) shows the relationship between Iwf / Iw, which is the ratio of the leakage current Iwf to the current Iw in the side wing region of the magnetic sensing element obtained from FIG. 6, and Lg / Lf, which is the ratio of the spacing Lg between adjacent side wing regions of the magnetic sensing element to the connection width Lf. Increasing Lg / Lf from 0.1 to 1 results in a slight decrease in Iwf / Iw, but the change is smaller than the relationship shown in FIG. 7. A large Lg / Lf is desirable to ensure the area of ​​the region where the MFC magnetic layers 11a, 11b and the insulating layer 15b overlap, thereby increasing the efficiency of magnetic field convergence from the MFC magnetic layers 11a, 11b to the magnetoresistance element 10.

[0029] (Second Example) 9 shows a second embodiment of the present invention, where (A) is a plan view in the first and second directions, and (B) is a cross-sectional view of the portion BB in the third and second directions. In the second embodiment, the magnetoresistive element film is composed of a magnetic sensing element current-carrying pivot portion 910b and magnetic sensing element side wing portions 910a and 910c, and also has a pair of MFC magnetic layers 911a and 911b. The gap along the second direction between the magnetic sensing element current-carrying pivot 910b of the magnetoresistive element 910 and the MFC magnetic layer 911a is defined as g1, and the gap along the second direction between the magnetic sensing element current-carrying pivot 910b of the magnetoresistive element 910 and the MFC magnetic layer 911b is defined as g2, where g1 and g2 are larger than Lf. From the descriptions of Figures 7 and 8, when g1 and g2 are larger than Lf, the leakage current to the magnetic sensing element current-carrying pivots 910b and 910c is limited to the range between g1 and g2, and no leakage current occurs in the overlapping region of the pair of MFC magnetic layers 911a and 911b. The gap g along the second direction between the MFC magnetic layers 911a and 911b is defined as g≧2Lf+W. Therefore, as shown in the figure, leakage current can be suppressed even if the MFC magnetic layers 911a, 911b and the insulating layer 15b are directly stacked in the overlapping area with the insulating layer 15b sandwiched between them, without the insulating layer. Alternatively, the insulating layer 15 can be made thinner without worrying about insulation defects such as pinholes. Narrowing the gap in the overlapping area with the MFC magnetic layers 911a, 911b and the insulating layer 15b sandwiched between them can improve the magnetic flux convergence efficiency of the magnetoresistive element 910.

[0030] (Third Example) A third embodiment is shown in Figures 10 and 11. As with Figures 1 and 2, Figure 10 is a plan view taken along the first and second directions, and Figure 11 is a cross-sectional view of the AA section taken along the third and second directions. In Figures 10 and 11, parts that have the same functions as those in Figures 1 and 2 are designated by the same reference numerals, and their explanation will be omitted. The wiring layer 16 is formed on the surface of the substrate 12 on which the pair of MFC magnetic layers 11a, 11b are formed, and is arranged so as to overlap the magnetic sensing element current-carrying pivot part 10b in the film thickness direction, and the longitudinal direction of the wiring layer 16 coincides with the current-carrying direction of the magnetic sensing element current-carrying pivot part 10b. The wiring 16 is connected to an AC power source 24, and passes an AC current along the current-carrying direction of the magnetic sensing element current-carrying pivot part 10b. As shown in Patent Document 2, a signal modulated by an AC current flowing through wiring 16 is detected by a signal voltage detection unit 22. AC modulation reduces noise, which is expected to increase the signal-to-noise ratio and enable the detection of weaker magnetic fields.

[0031] The magnetic sensor of the present invention can detect extremely weak magnetic fields of the picotesla (pT) order, which are required for magnetoencephalography and magnetocardiography, for example. Engineers in fields that handle such extremely weak magnetic fields had predicted that if side wing portions of the magnetic sensing element were further provided on the current-carrying pivot portion of the magnetic sensing element, the side wing portions would act as antennas and increase magnetic noise, but surprisingly, in a demonstration experiment of a magnetic sensor in which side wing portions of the magnetic sensing element were further provided on the current-carrying pivot portion of the magnetic sensing element, it was discovered that magnetic noise did not increase. It was also confirmed that the steep gradient of the magnetic resistance characteristics and high sensitivity can be maintained even when a magnetic sensor with a narrower width W of the magnetic sensing element current-carrying pivot part is used. For example, by providing magnetic sensing element side wing parts on both sides of the magnetic sensing element current-carrying pivot part in the width direction, the second direction length (W f +W+W f ) is 10 μm or more, the resistance of the GMR at the current-carrying pivot of the magnetic sensing element becomes constant, and it was confirmed that the current leakage at the side wing of the magnetic sensing element does not increase.

[0032] The above describes embodiments of the present invention with reference to specific examples. However, the embodiments of the present invention are not limited to these specific examples. For example, in the example shown in FIGS. 1 and 2, the side wing portions 10a and 10c are overlapped with the insulating layer 15b in the thickness direction of the magnetoresistive element 10. However, the embodiments of the present invention are not limited to this. The side wing portions 10a and 10c may be overlapped with the insulating layer 15b in the thickness direction of the magnetoresistive element 10, or may be overlapped with the side wing portions 10a and 10c directly in the thickness direction of the magnetoresistive element 10 without an insulating layer or a high resistance layer. Furthermore, for example, the specific configurations of the magnetic sensing element current-carrying pivot portion, the magnetic sensing element side wing portions, and the pair of MFC magnetic layers can be appropriately selected from known ranges by those skilled in the art. Furthermore, as long as the present invention can be implemented in a similar manner and similar effects can be obtained, it is included in the scope of the present invention.

[0033] Furthermore, any combination of two or more elements of each specific example within the scope of technical feasibility is also included within the scope of the present invention as long as it includes the gist of the present invention. In addition, all magnetic sensor devices and diagnostic devices that can be implemented by a person skilled in the art by appropriately modifying the design based on the magnetic sensor described above as an embodiment of the present invention also fall within the scope of the present invention, as long as they include the gist of the present invention.

[0034] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Industrial Applicability]

[0035] The magnetic sensor of the present invention is suitable for use in magnetic sensor devices, imaging diagnostic devices such as magnetoencephalographs and magnetocardiographs, and non-destructive testing devices. [Explanation of symbols]

[0036] 10, 310, 410, 510, 910 Magnetic sensing element (MR element) 10a, 310a, 410a, 510a, 910a Magnetic sensing element lateral wing part (+) 10c, 310c, 410c, 510c, 910c Magnetic sensing element lateral wing (-) 10b, 310b, 410b, 510b, 910b Magnetic sensing element current-carrying pivot 11a, 311a, 411a, 511a, 911a Magnetic flux convergence layer (MFC) 11b, 311b, 411b, 511b, 911b Magnetic flux convergence layer (MFC) 12 PCB 15a, 15b Insulator layers 16 wiring layer 20 constant current source 22 Signal voltage detection section 24 AC power supply 101 Base layer 102 pinned layer (first magnetic layer) 103 Intermediate layer (non-magnetic layer) 104 Free layer (second magnetic layer) 105 Cap Layer g The distance between a pair of MFC magnetic layers along the second direction Lf: Connection width of the side wing of the magnetic sensing element with the magnetic sensing element current-carrying pivot part Lg: Distance between adjacent lateral wings of the magnetic sensing element W Width of the magnetic sensing element current-carrying pivot Wf: Extension length of the lateral wings of the magnetic sensing element 1st direction: Current flow direction of the current-carrying pivot Second direction: In-plane direction of the current-carrying pivot, perpendicular to the first direction Third direction: the film thickness direction of the magnetoresistive element

Claims

1. A magnetoresistance element having a multilayer film in which a first magnetic layer, a non-magnetic layer and a second magnetic layer are sequentially laminated, the magnetoresistance element comprising: a current-carrying pivot part; and a plurality of side wing parts provided on an inner edge of a plane in a direction perpendicular to a current-carrying direction of the current-carrying pivot part and separated by insulating or high-resistance regions along the current-carrying direction; a pair of flux convergence magnetic layers disposed on both sides of the current-carrying pivot portion along an in-plane orthogonal direction, the flux convergence magnetic layers having portions overlapping the side wing portions in a film thickness direction of the magnetoresistive element; Magnetic sensor.

2. 2. The magnetic sensor according to claim 1, further comprising a region in which the flux concentrating magnetic layer does not overlap with the current-carrying pivot portion.

3. Regarding the shape of the side wing portion, when the length in the current-carrying direction at the connection portion between the side wing portion and the current-carrying pivot portion is Lf, and the interval in the current-carrying direction at the connection portion between the adjacent side wing portion and the current-carrying pivot portion is Lg, Lg<Lf The shape satisfies the following relation: The magnetic sensor according to claim 2 .

4. Regarding the shape of the current-carrying pivot portion and the side wing portion, when the length of the current-carrying pivot portion in the in-plane orthogonal direction is W, the connection width of the side wing portion with the current-carrying pivot portion is Lf, and the length of the side wing portion along the in-plane orthogonal direction is Wf, Lf<W and Lf<Wf The shape satisfies the following relation:

4. The magnetic sensor according to claim 1.

5. When the width of the current-carrying pivot portion is W and the extension length of the side wing portion is Wf, W<Wf The shape satisfies the following relation: The magnetic sensor according to claim 1 .

6. the interface between the flux concentrator magnetic layer and the magnetoresistive element is separated by an insulating or highly resistive region; The magnetic sensor according to claim 1 .

7. 2. The magnetic sensor according to claim 1, wherein the flux convergence magnetic layer and the magnetoresistive element are in contact with each other in a film thickness direction.

8. Let g be the distance between the pair of magnetic flux convergence magnetic layers provided on either side of the current-carrying direction of the current-carrying pivot part, W be the width of the current-carrying pivot part, and Lf be the connection width of the side wing part and the current-carrying pivot part. W+2Lf≦g and Wf>Lf The shape satisfies the following relation: The magnetic sensor according to claim 7.

9. Further, the film has an AC current-carrying wiring provided so as to overlap the current-carrying pivot portion in the film thickness direction. The magnetic sensor according to claim 1 .

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