JP4245007B2 - Magnetic sensor - Google Patents

Description

  The present invention relates to a magnetic sensor including a giant magnetoresistive element and a coil for generating a magnetic field applied to the giant magnetoresistive element.

  Conventionally, a magnetic sensor employing a magnetoresistive effect element such as a giant magnetoresistive effect element (GMR element) or a magnetic tunnel effect element (TMR element) as a magnetic field detection element is known. Such a magnetic sensor may include a coil 110 for applying a bias magnetic field to the magnetoresistive element 100 as shown in FIG. In this case, the coil 110 is formed in a spiral shape, and the magnetoresistive effect element 100 is formed above the periphery of the spiral of the coil 110. A bias magnetic field for the magnetoresistive effect element 100 is generated by a current flowing through each conductor of the coil 110 located immediately below the magnetoresistive effect element 100.

  However, according to the above-described conventional technique, there are many portions of the coil 110 that do not directly contribute to the formation of the bias magnetic field, and the occupied area of the coil 110 is increased, so that the coil 110 is reduced in size of the magnetic sensor. There is a problem of becoming an obstacle. In addition, since the entire length of the coil 110 is increased and the resistance thereof is increased, the power consumption for generating the bias magnetic field is increased, or a desired current cannot be ensured depending on the power supply voltage. There is also a problem that it is difficult to form a bias magnetic field.

One aspect of the present invention has been made to address the above-described problems. According to the present invention,
A pinned layer including a pinned layer whose magnetization direction is fixed, a thin-film giant magnetoresistive element including a conductive spacer layer and a free layer;
A magnetic sensor including a coil that is formed in a plane parallel to the film plane of the giant magnetoresistive element and generates a magnetic field applied to the magnetoresistive element;
In order to stabilize the magnetization direction of the free layer in a state where an external magnetic field is not applied to the giant magnetoresistive effect element, the giant magnetoresistive effect element is disposed at both ends of the giant magnetoresistive effect element and is uniaxial to the free layer. A bias magnet film that generates a magnetic field in the same direction as the direction of magnetization due to anisotropy,
The coil is
A first conductor that forms a spiral in plan view and a second conductor that forms a spiral in plan view;
The giant magnetoresistive element is disposed between the vortex center of the first conductor and the vortex center of the second conductor in plan view,
The first conductive wire portion located in a portion overlapping the giant magnetoresistive effect element in plan view and the second lead wire portion located in a portion overlapping the giant magnetoresistive effect element in plan view are substantially in the same direction. The first conductor and the second conductor are connected so that the current flows, and the widths of the first and second conductors located in a portion overlapping the giant magnetoresistive element in plan view Is formed so as to be narrower than the respective widths of the first and second conducting wires located in other parts,
A magnetic sensor is provided that is a coil that generates a magnetic field in the same direction as the magnetization direction due to uniaxial anisotropy of the free layer to initialize the magnetization direction of the free layer.

  According to this, the giant magnetoresistive effect element is arranged between the vortex center of the spiral first conductor wire in plan view and the vortex center of the spiral second conductor wire in plan view, and A current in substantially the same direction is applied to the portion of the first conductor located in a portion overlapping the magnetoresistive element in plan view and the portion of the second conductor located in a portion overlapping the giant magnetoresistive element in plan view. Flows. As a result, since many portions of the conductive wire forming the coil can be used for generating a magnetic field applied to the giant magnetoresistive effect element, the area occupied by the coil can be reduced.

  In this case, the portion of the first conducting wire positioned in a portion overlapping the giant magnetoresistive effect element in plan view and the portion of the second conducting wire located in a portion overlapping the giant magnetoresistive effect element in plan view are: It is preferable that they are formed in straight lines parallel to each other.

  As a result, a current parallel to each of the conducting wires that pass directly under the giant magnetoresistive effect element (located in a portion overlapping with the giant magnetoresistive effect element in a plan view) flows, and is thus generated by the current flowing in each conducting wire. The magnetic fields do not cancel each other. Therefore, the magnetic field to be applied to the giant magnetoresistive element can be generated efficiently (without wasting power).

  Further, the first and second conductors located in a portion overlapping the giant magnetoresistive effect element in plan view have the same width, and the first and second conductors located in other portions. It is preferable that the width is different from each other.

  According to this, it is possible to reduce the resistance value of the entire coil while flowing a current of a magnitude necessary for generating a magnetic field of a predetermined magnitude to each of the conducting wires passing directly under the giant magnetoresistive element. Therefore, power consumption can be reduced.

  Further, the coil is employed as a coil that generates a magnetic field that initializes the magnetization direction of the free layer of the giant magnetoresistive effect element including the free layer and the pinned layer. The magnetic sensor is disposed at both ends of the giant magnetoresistive element and stabilizes the magnetization direction of the free layer when no external magnetic field is applied to the giant magnetoresistive element. And a bias magnet film for generating a magnetic field in the same direction as the magnetization direction due to the uniaxial anisotropy of the free layer.

  With the above configuration, the coil generates an initialization magnetic field for returning the magnetization direction of the free layer to the designed direction (the direction of the bias magnetic field by the bias magnet film) under a predetermined condition. Even if the magnetization direction of the free layer is disturbed due to some reason such as adding to the sensor (ie, even when the magnetic domain becomes unstable), this can be corrected and reliability is improved. A high magnetic sensor is provided.

  Embodiments of a magnetic sensor according to the present invention will be described below with reference to the drawings. The magnetic sensor 10 according to the first embodiment shown in FIG. 1 which is a schematic plan view is made of, for example, SiO 2 / Si, glass or quartz, and is substantially square having sides along the X axis and the Y axis perpendicular to each other. , A substrate 10a having a thickness in the direction of the Z-axis perpendicular to the X-axis and the Y-axis, two thin-film magnetic tunnel effect elements (groups) 11 and 12, and the magnetic tunnel effect elements 11 and 12 externally In order to apply a bias magnetic field for magnetic field detection (measurement), the film plane of the thin film is below each of the magnetic tunnel effect elements (groups) 11 and 12 (on the substrate 10a side, that is, the Z-axis negative direction side). And bias magnetic field coils 21 and 22 formed in a plane parallel to (i.e., the XY plane).

  The magnetic tunnel effect elements (groups) 11 and 12 and the bias magnetic field coils 21 and 22 have the same structure except for the position and the orientation with respect to the substrate 10a. Therefore, hereinafter, the magnetic tunnel effect element (group) 11 and the bias magnetic field coil 21 will be described as representative examples with reference to FIGS.

  FIG. 2 is a partially enlarged plan view showing the shapes and relative positions of the magnetic tunnel effect element (group) 11 and the bias magnetic field coil 21. In this figure, an upper electrode, an interlayer insulating layer and the like which will be described later of the magnetic tunnel effect element 11 are omitted. 3 and 4 are cross-sectional views of the magnetic tunnel effect element 11 and the bias magnetic field coil 21 cut along the plane along line 1-1 and the line 2-2 in FIG. is there.

  The magnetic tunnel effect element 11 includes a first insulating layer 10b formed on the substrate 10a and a second insulating layer 10c formed on the first insulating layer 10b. Lead wires 21a and 21b made of Al (aluminum) connected to both ends of the bias magnetic field coil 21 are buried in the first insulating layer 10b, and the bias magnetic field coil 21 made of Al is buried in the second insulating layer 10c. Is buried.

  On the second insulating layer 10c, a lower electrode 11a having a planar shape of a rectangle having sides along the X-axis and the Y-axis and having a thickness in the Z-axis direction is formed. The lower electrode 11a is formed to a thickness of about 30 nm from Ta (Cr, Ti may be used) which is a conductive nonmagnetic metal material. On the lower electrode 11a, an antiferromagnetic film 11b made of PtMn having the same planar shape as the lower electrode 11a and a film thickness of about 15 nm is formed.

  On the antiferromagnetic film 11b, as shown in FIG. 4, a pair of ferromagnetic films 11c and 11c made of NiFe having a thickness of about 20 nm are stacked with a gap in the X-axis direction. Each of the ferromagnetic films 11c and 11c is a thin film having a rectangular shape having a short side and a long side along the X-axis and the Y-axis, respectively, and having a thickness in the Z-axis direction. Are arranged so as to face each other in parallel. The ferromagnetic films 11c and 11c constitute a pinned layer in which the magnetization direction is weakly fixed (pinned) in the short side direction (X-axis positive direction) by the antiferromagnetic film 11b. That is, the ferromagnetic films 11c and 11c and the antiferromagnetic film 11b form a layer generally called a fixed layer, and are also called a sense layer in this embodiment.

  On each ferromagnetic film 11c, an insulating layer 11d having the same planar shape as that of the ferromagnetic film 11c is formed. The insulating layer 11d is made of Al2O3 (Al-O), which is an insulating material, and is formed to have a thickness of about 1 nm.

  On each insulating layer 11d, a ferromagnetic film 11e made of NiFe having the same planar shape as the insulating layer 11d and having a thickness of about 80 nm is formed. The ferromagnetic film 11e forms a free layer (free magnetization layer) whose magnetization direction changes according to the direction of the external magnetic field, and is magnetic together with the pinned layer made of the ferromagnetic film 11c and the insulating layer 11d. A tunnel junction structure is formed. That is, the antiferromagnetic film 11b, the ferromagnetic film 11c, the insulating layer 11d, and the ferromagnetic film 11e constitute one magnetic tunnel effect element (excluding electrodes and the like). In the present embodiment, the ferromagnetic film 11e is also referred to as a reference layer.

  On each ferromagnetic film 11e, a dummy film 11f having the same planar shape as each ferromagnetic film 11e is formed. The dummy film 11f is made of a conductive nonmagnetic metal material made of a Ta film having a thickness of about 40 nm.

  In a region covering the second insulating layer 10c, the lower electrode 11a, the antiferromagnetic film 11b, the ferromagnetic film 11c, the insulating layer 11d, the ferromagnetic film 11e, and the dummy film 11f, an interlayer insulating layer 10d is provided. The interlayer insulating layer 10d is made of SiO2, and its film thickness is about 250 nm.

  In the interlayer insulating layer 10d, contact holes 10d1 and 10d1 are formed on the respective dummy films 11f. Upper electrodes 11g and 11g made of, for example, 300 nm-thickness Al are formed so as to bury this contact hole 10d1 and to electrically connect each of the pair of dummy films 11f and 11f to an IC circuit (not shown). . In this manner, the lower electrode 11a and the upper electrodes 11g and 11g electrically connect the ferromagnetic films 11e and 11e having a pair of magnetic tunnel junction structures and the ferromagnetic films 11c and 11c, respectively. A magnetic tunnel effect element (group) 11 is formed in which the magnetization directions of the layers are the same and a plurality of (a pair of) magnetic tunnel junction structures are connected in series. A protective film 10e made of SiO and SiN is formed on the upper electrodes 11g and 11g.

  The aforementioned bias magnetic field coil 21 is for applying an alternating bias magnetic field that varies along the Y-axis direction to the magnetic tunnel effect element (group) 11, as shown in FIG. In a plan view (in a plan view), the linear conductor wire is bent at a right angle in the XY plane (in a plane parallel to the plane formed by each thin film of the magnetic tunnel effect element 11). This means that the magnetic sensor is viewed along the Z-axis from the position, and the same applies hereinafter.) A pair of spirals having substantially the same shape is formed. That is, the bias magnetic field coil 21 is a first conductor (first wire) that forms a spiral whose diameter from the vortex center P1 gradually increases as it rotates counterclockwise (may be clockwise) in plan view. 1 coil portion) 21-1 and a second conductor (second coil portion) 21-2 forming a spiral whose diameter from the vortex center P2 gradually increases as it rotates counterclockwise in plan view. ing. Hereinafter, in order to distinguish this coil 21 from a conventional coil (single spiral type coil), it may be referred to as a double spiral type coil.

  The magnetic tunnel effect element 11 is disposed between the vortex center P1 of the first conducting wire 21-1 and the vortex center P2 of the second conducting wire 21-2 in plan view. Then, when a predetermined potential difference is applied to the lead portions 21a and 21b, the bias magnetic field coil 21 is positioned on each conductor wire that is at least overlapped with (passes through) the magnetic tunnel effect element 11 in plan view. The outermost peripheral portions of the first conducting wire 21-1 and the second conducting wire 21-2 are connected in an S shape so that currents in the same direction flow.

  Here, the operation (magnetic field detection principle) of the magnetic tunnel effect element 11 configured as described above will be described. As described above, the magnetization of the ferromagnetic film 11c of the sense layer is weakly pinned in the short side direction (X-axis positive direction). A magnetic field whose magnitude and direction change in the direction along the long side of the ferromagnetic film 11c (that is, the Y-axis direction and the direction perpendicular to the direction of pinned magnetization) with respect to the ferromagnetic film 11c. When applied, the magnetization direction of the sense layer (ferromagnetic film 11c) gradually changes (rotates), and the magnetization of the sense layer in the change direction of the same magnetic field changes as shown in FIG. That is, the magnetization (magnitude) of the sense layer is substantially constant when the magnitude of the magnetic field is larger than the saturation magnetic field H1 and smaller than the saturation magnetic field H2, and the same magnetic field is within the range of the saturation magnetic fields H2 to H1. In this case, the magnitude of the magnetic field changes approximately proportionally (substantially linearly).

  On the other hand, when the above-described magnetic field (a magnetic field whose magnitude and direction changes in the Y-axis direction) is applied to the ferromagnetic film 11e of the reference layer, the magnetization of the reference layer in the changing direction of the magnetic field is as shown in FIG. To change. That is, the magnetization of the reference layer becomes substantially constant when the magnitude of the magnetic field is larger than the saturation magnetic field H3 and smaller than the saturation magnetic field H4, and the magnitude of the magnetic field is equal to the saturation magnetic fields H3 and H4. When it agrees with, it changes to step shape. This magnetization characteristic of the reference layer is due to the shape anisotropy of the ferromagnetic film 11e whose magnetization direction is aligned in the longitudinal direction.

  As a result, the resistance R of the magnetic tunnel effect element 11 changes as shown in FIG. In FIG. 7, a solid line indicates a change in resistance value when the magnetic field changes from negative to positive, and a broken line indicates a change in resistance value when the magnetic field changes from positive to negative. As is clear from FIG. 7, the resistance value is an even function with respect to the magnetic field (when the magnetic field is taken on the x-axis and the resistance is taken on the y-axis orthogonal to the x-axis, the resistance is axisymmetric with respect to the y-axis).

  In the magnetic sensor 10, the coil 21 is used to form a triangular wave as shown in FIG. 8 in the Y-axis direction (long side direction of the ferromagnetic film 11e) with respect to the magnetic tunnel effect element 11. A changing AC bias magnetic field HAC is applied. This AC bias magnetic field HAC is linear between a maximum value Hmax (= Ha> 0) and a minimum value Hmin equal to a value obtained by inverting the sign of the absolute value of the maximum value Hmax (= −Ha) in a cycle 4T. It is a magnetic field that changes (sweep). The maximum value Hmax of the AC bias magnetic field HAC is greater than the saturation magnetic field H3 of the reference layer and smaller than the saturation magnetic field H1 of the sense layer. Similarly, the minimum value Hmin of the AC bias magnetic field is smaller than the saturation magnetic field H4 of the reference layer and larger than the saturation magnetic field H2 of the sense layer.

  When such an AC bias magnetic field HAC is applied to the magnetic tunnel effect element 11 and the external magnetic field h to be detected is changed in a direction parallel to the AC bias magnetic field HAC, the resistance R of the magnetic tunnel effect element 11 is changed. Changes as shown in FIG. In FIG. 9, an alternate long and short dash line A indicates that the external magnetic field h to be detected is “0”, a solid line B indicates that the external magnetic field h is a positive predetermined value, and a broken line C indicates that the external magnetic field h is a negative predetermined value. The resistance R in each case is shown.

On the other hand, in the magnetic sensor 10, from the first time point when the resistance R of the magnetic tunnel effect element 11 crosses the predetermined threshold value Th from the top to the bottom, the second time point when the resistance R crosses the threshold value Th from the top to the bottom. Time x (or x1, x2) and time y (or y1, y2) from the second time point to the third time point when the resistance R further crosses the threshold value Th from the top to the bottom. 1 includes an IC circuit (not shown) that outputs a detection value D indicated by 1.
D = y / (x + y) Equation 1

  As shown in FIG. 10, the detected value (duty) D is proportional to (the magnitude of) the external magnetic field h to be detected and changes depending on the maximum value Ha of the AC bias magnetic field HAC. On the other hand, the detected value D does not depend on the output characteristic change of the magnetic tunnel effect element 11. Therefore, the magnetic tunnel effect element 11 compensates for the change in output characteristics of the magnetic tunnel effect element (group) 11 due to a change in element temperature or a change with time, and a very small magnetic field in the Y-axis direction. Can be detected with high accuracy. The time x (or x1, x2) is from the first time point when the resistance R crosses the predetermined threshold Th from the bottom to the top until the second time point when the resistance R crosses the threshold Th from the bottom to the top. The time y (or y1, y2) may be the time from the second time point to the third time point when the resistance R further crosses the threshold value Th from the bottom to the top. The detection value D may be D = x / (x + y).

  Referring again to FIG. 1, the bias magnetic field coil 21 is connected to a control circuit (not shown) and applies the AC bias magnetic field HAC to the magnetic tunnel effect element 11. On the other hand, the magnetic tunnel effect element 12 is the same as that formed on the substrate 10a with the magnetic tunnel effect element 11 rotated counterclockwise by 90 °. The bias magnetic field coil 22 is connected to a control circuit (not shown) and applies the AC bias magnetic field HAC that changes in the X-axis direction to the magnetic tunnel effect element 12. As a result, the magnetic tunnel effect elements 11 and 12 constitute a Y-axis magnetic sensor that detects a magnetic field in the Y-axis direction and an X-axis magnetic sensor that detects a magnetic field in the X-axis direction, respectively.

  By the way, since each of the coils 21 and 22 is a double spiral type coil in which a pair of spirals is formed in a plan view, the occupied area is small and the power consumption is small. This point will be described below in comparison with the coil 21 shown in FIG. 2 and the conventional coil 110 shown in FIG. For easy comparison, in FIGS. 2 and 33, the width of the conductors forming each coil and the width of the space between adjacent conductors are made the same, and the magnetic tunnel effect element 11 is used. , 100 in which 9 conductors pass through immediately below (portions overlapping the magnetic tunnel effect elements 11, 100 in plan view).

  First, considering the occupied area, the coil 21 has a larger proportion of the entire conductive wire portion that directly contributes to the generation of the bias magnetic field (the portion of the conductive wire that passes directly below the magnetic tunnel effect element 11). It can be clearly seen that it is small. Actually, the conventional coil 110 shown in FIG. 33 has a width of 5.6 μm, a space between adjacent conductors of 0.7 μm, and the size of the magnetic tunnel effect elements 11 and 100 of 120 × 64 μm 2. The area of the coil 110 was 282 × 332 μm 2, whereas the area of the double spiral coil 21 shown in FIG. 2 was 191 × 286 μm 2.

  Next, when the bias magnetic field coil is a single spiral type as in the conventional coil 110 and a double spiral type as in the coil 21, the sizes of the magnetic tunnel effect elements 11 and 100 are different. Were both 60 × 120 μm 2, and the electrical numerical values of the respective coils when a bias magnetic field of 15 Oe was generated in the region were examined. The results are shown in Table 1.

  In Table 1, patterns A to D are conventional single spiral coils, and patterns E and F are double spiral coils according to the present invention. Further, “a” in Table 1 represents the width of a conducting wire (conducting wire that directly contributes to the generation of a bias magnetic field) that passes directly under each of the magnetic tunnel effect elements 11 and 100, as shown in FIGS. , “B” is the width of the conductive wire extending in parallel with the long sides of the magnetic tunnel effect elements 11 and 100 (that is, the width of the conductive wire on both sides in the X-axis direction of the magnetic tunnel effect elements 11 and 100), and “c” is the magnetic tunnel. The width of the conducting wire that is not directly under the effect elements 11 and 100 and extends in parallel with the short sides of the magnetic tunnel effect elements 11 and 100, “N” is the number of vortex turns, “R” is the resistance of each coil, “ “I” is the current of each coil, “V” is the voltage across each coil, and “W” is the power consumption of each coil. In any part of each coil, the width of the space between the adjacent conductors was 0.7 μm.

The method for obtaining each numerical value shown in Table 1 will be briefly described. First, in order to generate a magnetic field of 1 Oe on the upper part of the coil, the current i (that is, the current required per unit width of the conducting wire constituting the coil). Density). Then, by taking into consideration the current i and the coil conductor width a and the sum of the space widths between adjacent conductors (a + 0.7) μm, a magnetic field of 15 Oe is generated in the upper part of the coil according to the following formula 2. Therefore, the current I necessary for this is obtained.
I = i · 15 · (a + 0.7) ... number 2

  On the other hand, the number of turns N of the coil is obtained by dividing the length of the long side of the element (120 μm) by the sum of the width of the coil and the space between adjacent conductors (a + 0.7) μm. As a result, the shape of the coil is determined, so that the total length of the coil, the sheet resistance value of the material used for the coil (in this case, Al), and the conductor wire widths “a”, “b”, “c” of each part of the coil Therefore, the resistance R is obtained from the current I and the voltage V and the power consumption W are obtained from the current I and the resistance R.

  As can be seen from Table 1, when the conductor widths a to c are all the same, the conventional single spiral coil shown in the patterns A to D has a larger current I as the conductor widths a to c are increased. Thus, the number of turns N and the voltage V are reduced. The power consumption W takes a minimum value when each of the conductor widths a to c is about 4 μm (see pattern C).

  On the other hand, the double spiral type coil according to the present invention shown in the pattern E can make the resistance R, the voltage V between both ends, and the power consumption W very small as compared with the conventional coil. For example, as can be understood from the comparison between the pattern D and the pattern E, the power consumption of the coil of the pattern E can be reduced to about half that of the conventional coil of the pattern D. Compared with the coil of the pattern C whose power consumption W is near the minimum value, the power consumption W of the coil of the pattern E can be considerably reduced.

  Further, as can be seen from Table 1, the voltage V across the coil according to the present invention can be reduced. Therefore, the coil according to the present invention can generate a magnetic field having a required magnitude even when the power supply voltage is low. In addition, as can be understood from the comparison between the pattern E and the pattern F, by adjusting the conductive wire widths b and c of the portion of the coil of the present invention that is not located immediately below the element, that is, the magnetoresistive effect. The widths a of the first and second conductors located in a portion overlapping the magnetic tunnel effect element 11 as an element in plan view are equal to each other, and the first and second second conductors located in other portions are the same. The power consumption W can be further reduced by forming it different from the widths b and c of the conducting wire.

  As described above, according to the first embodiment, since the TMR element having the sense layer and the reference layer is configured to apply the bias magnetic field to detect the external magnetic field, the magnetic field with small change in detection characteristics can be obtained. A sensor is obtained. In addition, according to the first embodiment, since the coil is of a double spiral type, a small and low power consumption magnetic sensor is provided. Each of the magnetic tunnel effect elements (groups) 11 and 21 of the magnetic sensor 10 has a pair of magnetic tunnel effect elements connected in series, but more magnetic tunnel effect elements are connected in series. It may be a thing.

  Next, a second embodiment of the magnetic sensor according to the present invention will be described. While the magnetic sensor of the first embodiment employs a TMR element, the magnetic sensor of the second embodiment includes a pinned layer. The difference is that a GMR element (giant magnetoresistive effect element) composed of a layer, a spacer layer, and a free layer is employed. The coils 21 and 22 of the first embodiment generate a bias magnetic field for detecting an external magnetic field, but the coil of the second embodiment initializes the magnetization direction of the free layer of the GMR element. The difference is that a magnetic field for initialization is generated.

  More specifically, as shown in FIG. 11, the magnetic sensor 30 according to the second embodiment has a rectangular shape (substantially square shape) having sides along the X axis and the Y axis orthogonal to each other. A substrate 30a made of quartz glass having a small thickness in the Z-axis direction orthogonal to the X-axis and the Y-axis, a total of eight GMR elements 31 to 38 formed on the substrate 30a, and a GMR element The coils 31 to 38 for applying an initialization magnetic field to the coils 31 to 38 are connected to the coils 41 to 48, respectively, and a predetermined potential difference is applied to both ends of the coils 41 to 48. The control circuit 51-58 to provide is provided.

  The first X-axis GMR element 31 is formed in the vicinity of the end of the X-axis negative direction below the central portion of the substrate 30a in the Y-axis direction, and the pinned magnetization direction of the pinned layer is the X-axis negative direction. . The second X-axis GMR element 32 is formed in the vicinity of the end of the X-axis negative direction above the center of the substrate 30a in the Y-axis direction, and the pinned magnetization direction of the pinned layer is the X-axis negative direction. . The third X-axis GMR element 33 is formed in the vicinity of the end of the X-axis positive direction above the central portion of the substrate 30a in the Y-axis direction, and the pinned magnetization direction of the pinned layer is the X-axis positive direction. . The fourth X-axis GMR element 34 is formed in the vicinity of the end of the X-axis positive direction under the substantially central portion of the substrate 30a in the Y-axis direction, and the pinned layer has a pinned magnetization direction in the X-axis positive direction. .

  The first Y-axis GMR element 35 is formed in the vicinity of the Y-axis positive direction end on the left side of the substantially central portion of the substrate 30a in the X-axis direction, and the pinned magnetization direction of the pinned layer is the Y-axis positive direction. Yes. The second Y-axis GMR element 36 is formed in the vicinity of the Y-axis positive direction end on the right side of the center portion of the substrate 30a in the X-axis direction, and the pinned magnetization direction of the pinned layer is the Y-axis positive direction. Yes. The third Y-axis GMR element 37 is formed in the vicinity of the Y-axis negative direction end on the right side of the central portion of the substrate 30a in the X-axis direction, and the pinned layer has a pinned magnetization direction in the Y-axis negative direction. Yes. The fourth Y-axis GMR element 38 is formed in the vicinity of the Y-axis negative direction end on the left side of the central portion of the substrate 30a in the X-axis direction, and the pinned layer has a pinned magnetization direction in the Y-axis negative direction. Yes.

  The GMR elements 31 to 38 and the coils 41 to 48 have the same structure except for the position and the direction with respect to the substrate 30a. Therefore, in the following, the first X-axis GMR element 31 and the coil 41 will be described as representative examples.

  The first X-axis GMR element 31 whose plan view is shown together with the coil 41 in FIG. 12 is an enlarged plan view of FIG. 13 and the first X-axis GMR element 31 and the coil along the plane 3-3 in FIG. As shown in FIG. 14, which is a schematic cross-sectional view taken along a line 41, a plurality of narrow strip portions 31a... 31a made of a spin valve film SV and having a longitudinal direction in the Y-axis direction, and Y of each narrow strip portion 31a. Bias magnet films (hard ferromagnetic thin film layers) 31b... 31b made of a material having a high coercive force and a high squareness ratio, which is a hard ferromagnetic material such as CoCrPt formed below both ends in the axial direction. Yes. Each narrow strip portion 31a extends in the X-axis direction on the upper surface of each bias magnet film 31b and is joined to the adjacent narrow strip portion 31a.

  As shown in FIG. 15, the spin valve film SV of the first X-axis GMR element 31 has a free layer (free layer, free magnetic layer) F sequentially stacked on the substrate 30 a and a film thickness of 2. Conductive spacer layer S made of 4 nm (24 Å) Cu, pinned layer (pinned layer, fixed magnetic layer) P, and capping made of 2.5 nm (25 Å) titanium (Ti) or tantalum (Ta) The layer C is configured to be included.

  The free layer F is a layer in which the direction of magnetization changes according to the direction of the external magnetic field. The NiFe magnetic layer 31-2 having a thickness of 3.3 nm (33 Å) formed on the layer 31-1 and the thickness of about 1 to 3 nm (10 to 30 Å) formed on the NiFe magnetic layer 31-2 The CoFe layer 31-3 has a thickness. The CoZrNb amorphous magnetic layer 31-1 and the NiFe magnetic layer 31-2 constitute a soft ferromagnetic thin film layer. The CoFe layer 31-3 prevents diffusion of Ni in the NiFe layer 31-2 and Cu31-4 in the spacer layer S. The above-described bias magnet films 31b to 31b maintain the uniaxial anisotropy of the free layer F in order to maintain the uniaxial anisotropy with respect to the free layer F (Y indicated by the wide arrows in FIGS. 12 and 13). A bias magnetic field is applied in the negative axis direction.

  The pinned layer P is a CoFe magnetic layer 31-5 with a thickness of 2.2 nm (22 Å) and an antiferromagnetic film 31-6 with a thickness of 24 nm (240 Å) formed from a PtMn alloy containing 45 to 55 mol% of Pt. Are superimposed. The CoFe magnetic layer 31-5 is back-coupled to the magnetized (magnetized) antiferromagnetic film 31-6 in an exchange coupling manner, so that the magnetization direction is pinned (fixed) in the negative X-axis direction as described above. )

  The first X-axis GMR element 31 configured as described above is substantially resistant to the external magnetic field in the range of −Hc to + Hc with respect to the external magnetic field changing along the X-axis, as shown by the solid line in FIG. It exhibits a resistance value that varies in proportion, and exhibits a substantially constant resistance value for an external magnetic field that varies along the Y-axis, as indicated by the broken line in FIG.

  In this magnetic sensor 30, as shown in FIG. 17, an X-axis magnetic sensor that detects a magnetic field in the X-axis direction is configured by full-bridge connection of the first to fourth X-axis GMR elements 31 to 34. . In FIG. 17, arrows attached to the respective GMR elements 31 to 34 indicate the directions of pinned magnetization of the pinned layers (pinned layers) of the GMR elements 31 to 34. In such a configuration, there is a constant potential difference between the coupling point Va between the second X-axis GMR element 32 and the third X-axis GMR element 33 and the coupling point Vb between the first X-axis GMR element 31 and the fourth X-axis GMR element 34. And a potential difference (Vc−) between a coupling point Vc between the first X-axis GMR element 31 and the third X-axis GMR element 33 and a coupling point Vd between the second X-axis GMR element 32 and the fourth X-axis GMR element 34. Vd) is taken out as sensor output Vout.

  As a result, the X-axis magnetic sensor changes substantially in proportion to the external magnetic field in the range of −Hc to + Hc with respect to the external magnetic field changing along the X-axis, as shown by the solid line in FIG. The output voltage Vxout is shown, and as shown by the broken line in FIG. 18, the output voltage is substantially “0” for the external magnetic field changing along the Y axis.

  Similar to the X-axis magnetic sensor, the Y-axis magnetic sensor is formed by full-bridge connection of the first to fourth Y-axis GMR elements 35 to 39, and with respect to an external magnetic field that changes along the Y-axis, −Hc In the range of + Hc, an output voltage Vyout that changes substantially in proportion to the external magnetic field is shown, and an output voltage of substantially “0” is shown for an external magnetic field that changes along the X axis. As described above, the magnetic sensor 30 can detect the external magnetic field without the need for the AC bias magnetic field HAC or the like for detecting the external magnetic field unlike the magnetic sensor 10.

  On the other hand, as shown in FIGS. 12 and 13, a bias magnetic field in the direction indicated by the wide arrow is applied from the bias magnet films 31b... 31b to the free layer F of the narrow strip portion 31a. It is designed so that the magnetization direction of the free layer F is constant in a state where no magnetic field is applied. However, when a strong external magnetic field is applied, the magnetization direction of the free layer F may be reversed at a position away from the bias magnet films 31b... 31b (near the center in the Y-axis direction in FIGS. 12 and 13). The characteristics of the GMR element will change.

  Therefore, in the present embodiment, a bias magnetic field for initializing the magnetization direction of the free layer F is applied by the coils 41 to 48 described above. Hereinafter, the first X-axis GMR element 31 and the coil 41 will be described in detail as representative examples. As shown in FIG. 12, the coil 41 is a double spiral type coil having a configuration similar to that of the bias magnetic field coil 21 of the first embodiment, and is a conducting wire forming a pair of spirals (that is, the first coil). , The second conductive wire 41-1 and the second conductive wire 41-2). The first X-axis GMR element 31 is disposed between the pair of vortex centers P1 and P2 in a plan view (viewed from the positive direction of the Z-axis). Furthermore, the portions of the first conducting wire 41-1 and the second conducting wire 41-2 that overlap the first X-axis GMR element 31 in the same plan view (portions that pass directly below the first X-axis GMR element 31) It is a parallel straight line, and currents in the same direction flow through the conductors in this portion, and the longitudinal direction of each conductor in the portion is orthogonal to the longitudinal direction of the narrow strip portion 31a in plan view. Further, the control circuit 51 shown in FIG. 11 applies a potential difference to both ends of the coil 41 under a predetermined condition such as before the start of measurement of the external magnetic field, thereby causing a predetermined current to flow through the coil 41. Yes.

  That is, the magnetic sensor of this embodiment is a magnetic sensor including a magnetoresistive effect element including a free layer such as a GMR element and a TMR element and a pinned layer, and magnetization of the free layer in a state where no external magnetic field is applied. The bias magnet 31b is arranged at both ends of the free layer and generates a bias magnetic field in a predetermined direction (a direction perpendicular to the pinned magnetization direction of the pinned layer) in the free layer. 31b is provided below (in close proximity to) the free layer, and generates a magnetic field in the same direction as the bias magnetic field when energized under a predetermined condition (for example, before the start of magnetic detection). The magnetic sensor includes initialization coils 41 to 48 that apply a magnetic field to the free layer.

  With the above configuration, the coil 41 generates an initialization magnetic field for returning the magnetization direction of the free layer F to the designed direction (the direction of the bias magnetic field by the bias magnet films 31b... 31b) under a predetermined condition. Even when the magnetization direction of the free layer F is disturbed for some reason, such as when a strong magnetic field is applied to the magnetic sensor (that is, even when the magnetic domain becomes unstable), this is corrected. And a highly reliable magnetic sensor is provided.

  Thus, in the second embodiment, since the magnetization direction of the free layer F can be initialized, the characteristics of the GMR element can be maintained at the initial characteristics. In addition, since each of the coils 41 to 48 is a double spiral type coil, the magnetic sensor 30 can be miniaturized by reducing the area occupied by the coil, and power consumption for initialization can be reduced. It becomes possible. Further, in the second embodiment, control circuits 51 to 58 for supplying a current for generating an initialization magnetic field are provided for the coils 41 to 48, respectively. Therefore, compared with the case where the coils 41 to 48 are connected in series and the current is flowed by one control circuit, the total length of the electrical connection path can be shortened, so that the overall resistance value can be reduced. Power consumption can be suppressed.

  Next, a third embodiment of the magnetic sensor according to the present invention will be described. FIG. 19 is a plan view of the magnetic sensor 60 according to the third embodiment. The magnetic sensor 60 is directed to the magnetic sensor 30 according to the second embodiment, and the directions of the coils 71 to 78 and the coils 71 to 78 are the same. The connection method between is different. The coils 41 to 48 of the magnetic sensor 30 generate an initialization magnetic field, whereas the coils 71 to 78 of the magnetic sensor 60 function normally (each external magnetic field is detected normally). This is different in that a test magnetic field is generated to determine whether or not the

  Specifically, the magnetic sensor 60 includes eight GMR elements 61 to 68 on the substrate 60a, and in a plane below the GMR elements 61 to 68 and parallel to the film planes of the GMR elements 61 to 68. Eight coils 71 to 78 each formed and one control circuit 79 are provided.

  The GMR elements 61 to 68 are the same as the GMR elements 31 to 38 of the second embodiment in position and configuration with respect to the substrate. That is, the GMR elements 61 to 64 are bridge-connected to constitute an X-axis magnetic sensor that detects a magnetic field in the X-axis direction, and the GMR elements 65 to 68 are similarly bridge-connected to detect a magnetic field in the Y-axis direction. Configure a magnetic sensor. Further, each of the GMR elements 61 to 68 is connected to a detection circuit (control LSI for detecting a magnetic field) (not shown) so that the resistance value exhibited by the GMR elements 61 to 68 is detected.

  The coils 71 to 78 are double spiral type coils similar to the coils 21 and 22 of the first embodiment and the coils 41 to 48 of the second embodiment. As shown by the wide arrows in FIG. 19, the coils 71 to 74 are formed so as to generate a magnetic field in the positive direction of the X axis in the vicinity of the line segment connecting the vortex centers. A Y-axis negative magnetic field is generated in the vicinity of the line segment connecting the centers. In addition, one end of the control circuit 79 and one end of the coil 76 are connected, and the coils 76, 75, 72, 71, 78, 77, 74, 73 are connected in series in this order, and finally the coil 74 of the coil 73 is connected. The unconnected end is connected to the other end of the control circuit 79. Furthermore, the GMR elements 61 to 68 are arranged between each corresponding pair of vortex centers in a plan view of the coils 71 to 78, as in the first and second embodiments.

  In such a configuration, when a predetermined condition such as the start of detection of an external magnetic field by the magnetic sensor 60 is established, the control circuit 79 generates a potential difference between the both ends, whereby a current flows through each of the coils 71 to 78. Magnetic fields for testing are applied to the GMR elements 61 to 68 by the coils 71 to 78, respectively. The magnetic sensor 60 monitors the output of each of the GMR elements 61 to 68 in this state by the detection circuit (not shown), and whether or not there is an abnormality in each of the GMR elements 61 to 68 based on whether or not a planned output is detected. Determine. The determination of the presence / absence of abnormality is performed, for example, on the presence / absence of an open failure of each GMR element 61-68, the presence / absence of a short (short circuit) failure, whether the sensitivity is insufficient, the presence / absence of abnormality of the control transistor, and the like.

  As described above, in the third embodiment, a magnetic field for determining the presence / absence of abnormality of each of the GMR elements 61 to 68 can be generated, so that the self-diagnosis of the magnetic sensor 60 can be performed. In addition, since each of the coils 71 to 78 is a double spiral type coil, the magnetic sensor 60 can be miniaturized by reducing the area occupied by the coil, and the power consumption for generating the test magnetic field is reduced. It becomes possible to do. Further, since the coils 71 to 78 are connected in series, and a current is simultaneously supplied by one control circuit 79, a test magnetic field having the same magnitude is generated for each of the GMR elements 61 to 68. Therefore, it is possible to determine the presence / absence of abnormality of each of the GMR elements 61 to 68 with higher accuracy.

  Further, when the detection circuit has a function of independently selecting one of the GMR elements 61 to 68, it is possible to easily detect whether or not the selection function is abnormal. This is because the test magnetic field is applied to all the GMR elements 61 to 68 at the same time. Therefore, if the selection function of the detection circuit is abnormal, for example, the GMR element that detects the magnetic field in the X-axis direction is selected. This is because an output corresponding to the magnetic field in the Y-axis direction can be obtained.

  Next, a fourth embodiment of the magnetic sensor according to the present invention will be described. FIG. 20 is a plan view of a magnetic sensor 80 according to the fourth embodiment. This magnetic sensor 80 includes two TMR elements 81 and 82 formed on a substrate 80a, and below each TMR element 81 and 82. And two test (test) coils 91 and 92 formed in a plane parallel to the film planes of the TMR elements 81 and 82, respectively. The magnetic sensor 80 includes a detection circuit 93, a current supply circuit 94, and a control circuit 95, which are formed on the substrate 80a.

  The TMR element 81 constituting the first magnetic detection unit (X-axis magnetic detection unit) has the same film structure as that of the TMR element described in the first embodiment (see FIGS. 3 and 4). However, the magnetization direction of the pinned layer of the TMR element 81 is strongly fixed (pinned) in the negative X-axis direction so that the magnetization direction does not change with respect to the external magnetic field to be detected. Further, the direction and magnitude of magnetization of the free layer of the TMR element 81 change linearly according to the direction and magnitude of the X-axis direction component of the magnetic field to be detected.

  As a result, the TMR element 81 has a detection direction indicated by a white arrow in FIG. That is, in the TMR element 81, as shown in FIG. 21, the magnitude of the magnetic field in the first direction (that is, the X-axis positive direction) in the first direction (that is, the X-axis direction) becomes a predetermined value. The resistance value, which is a physical quantity that increases as the value increases in the range up to 1, is shown, and the magnitude of the magnetic field in the direction opposite to the first direction in the first direction (that is, the negative direction of the X axis) is a predetermined value. The resistance value, which is a smaller physical quantity, is shown as it becomes larger within the range up to.

  If the characteristics of the TMR element 81 are normal, the magnetic field having a predetermined magnitude Hb from the first inspection coil 91 in the first direction (that is, the X-axis positive direction) in the first direction. Is applied, the resistance value Sx1 of the first magnitude is shown, the resistance value Sx2 is shown when no magnetic field is applied from the first inspection coil 91, and the first inspection coil 91 supplies the first value. When the magnetic field having the predetermined magnitude Hb is applied in the direction opposite to the first direction in the direction (that is, the negative direction of the X axis), the resistance value Sx3 having the second magnitude is shown.

  The TMR element 82 constituting the second magnetic detection unit (Y-axis magnetic detection unit) has a film structure similar to that of the TMR element 81, and the pinned layer of the TMR element 82 is strongly fixed in the negative direction of the Y-axis ( The direction of the same magnetization does not change with respect to the external magnetic field to be detected. The free layer of the TMR element 82 linearly changes the magnetization direction and magnitude according to the direction and magnitude of the Y-axis direction component of the magnetic field to be detected.

  As a result, the TMR element 82 has a detection direction indicated by a white arrow in FIG. That is, as shown in FIG. 22, the TMR element 82 is in the second direction (that is, the Y-axis direction) that intersects (is orthogonal to in this case) the first direction (that is, the X-axis direction). As the magnitude of the magnetic field in the second direction (i.e., the positive direction of the Y-axis) increases within a range until it reaches a predetermined value, the resistance value is a larger physical quantity and the second value in the second direction. The resistance value, which is a smaller physical quantity, is shown as the magnitude of the magnetic field in the direction opposite to the direction (that is, the negative Y-axis direction) becomes a predetermined value.

  If the characteristics of the TMR element 82 are normal, the magnetic field having a predetermined magnitude Hb from the second inspection coil 92 in the second direction (that is, the Y-axis positive direction) in the second direction. Is applied, the resistance value Sy1 is the same as the resistance value Sx1 as the physical quantity of the first magnitude, and when the magnetic field is not applied from the second inspection coil 92, the resistance value Sx1 is the same magnitude. The magnetic field having the predetermined magnitude Hb is applied from the second inspection coil 92 in a direction opposite to the second direction in the second direction (that is, in the negative Y-axis direction). When this is done, the resistance value Sy3 having the same magnitude as the resistance value Sx3, which is the physical quantity of the second magnitude, is shown.

  The first inspection coil 91 is a double spiral type coil formed in the same manner as the coil 22 of the magnetic sensor 10, and one end of the first inspection coil 91 is connected to one terminal P1 of the current supply circuit 94 via the connection conductor 96a. In addition, the other end is connected to one terminal of the second inspection coil 92 via the connection conductor 96b so that a magnetic field whose direction and magnitude change in the X-axis direction is applied to the TMR element 81. It has become. The second inspection coil 92 is a double spiral type coil formed in the same manner as the coil 22 of the magnetic sensor 10, and the other end is connected to the other terminal P2 of the current supply circuit 94 via the connection conductor 96c. In addition, a magnetic field whose direction and magnitude change in the Y-axis direction is applied to the TMR element 82.

  As described above, the first inspection coil 91 and the second inspection coil 92 are connected in series to the current supply circuit 94 via the connecting conductors 96a to 96c. 91 and the second inspection coil 92 are configured to have the same current. In addition, as shown by the black arrows in FIG. 20, when a current of a predetermined magnitude flows in the first inspection coil 91 in a predetermined direction, the first inspection coil 91 is X A magnetic field having a predetermined magnitude Hb in the positive axial direction is applied to the TMR element 81, and the second inspection coil 92 applies a magnetic field having the same predetermined magnitude Hb to the TMR element 82 in the negative Y-axis direction. When a current of the same predetermined magnitude is passed through the inspection coil 91 in a direction opposite to the predetermined direction, the first inspection coil 91 has a magnetic field of the same predetermined magnitude Hb in the negative X-axis direction. Is added to the TMR element 81, and the second inspection coil 92 is configured to apply a magnetic field of the same predetermined magnitude Hb to the TMR element 82 in the positive Y-axis direction.

  The detection circuit 93 selects either the TMR element 81 or the TMR element 82, detects the resistance value of the selected TMR element as a digital value, and outputs the detected digital value to the control circuit 95. 1 channel analog-digital converter 93a (hereinafter referred to as "ADC 93a") and actually a switching element 93b made of a transistor.

  One input terminal of the ADC 93a is connected to one end of each of the TMR element 81 and the TMR element 82, and the other input terminal is connected to a fixed terminal of the switching element 93b. The switching element 93b receives an instruction signal from the control circuit 95 and connects the fixed terminal to the other end of the TMR element 81 or the other end of the TMR element 82 in accordance with the instruction signal. An element for AD conversion of the resistance value is selected.

  The current supply circuit 94 includes a switching element MS, switching elements S1 to S4 constituting a current direction switching circuit (the switching element MS and switching elements S1 to S4 constitute an energization control circuit), and a constant current for supplying a constant current. A source (current supply source) IS is provided. The switching elements MS, S1 to S4 are actually transistors, and are switched to an “on” state (conducting state) or an “off” state (non-conducting state) in accordance with an instruction signal from the control circuit 95. It has become.

  The switching element MS functions as a so-called main switch, and one end is connected to the output side of the constant current source IS and the other end is connected to one end of each of the switching elements S1 and S3 of the current direction switching circuit. The other end of the switching element S1 is connected to one end of the switching element S2, and the other end of the switching element S2 is connected to the other end of the constant current source IS. Similarly, the other end of the switching element S3 is connected to one end of the switching element S4, and the other end of the switching element S4 is connected to the other end of the constant current source IS. The terminal P1 of the current supply circuit 94 to which the first inspection coil 91 is connected is connected between the switching elements S3 and S4, and the terminal of the current supply circuit 94 to which the second inspection coil 92 is connected. P2 is connected between switching elements S1 and S2.

  The control circuit 95 normally sends an instruction signal for turning off the switching element MS and the switching elements S1 to S4 of the current direction switching circuit to the switching elements MS and S1 to S4, and elapse of a predetermined time. Each time an instruction signal is supplied to the switching element 93b, a TMR element whose resistance value is AD converted by the ADC 93a is selected, and the resistance value of one of the TMR elements 81 and 82 subjected to AD conversion is acquired as a digital value. It is like that.

  Further, the control circuit 95 supplies an instruction signal for turning on the switching element MS to the main switch MS when a predetermined condition (inspection condition) such as turning on a switch (not shown) is satisfied, An instruction signal for setting the switching elements S1 and S4 of the current direction switching circuit to the "on" state and the switching elements S3 and S2 to the "off" state, or switching the switching elements S3 and S2 of the current direction switching circuit to the "on" state and switching An instruction signal for turning off the elements S1 and S4 is supplied to the switching elements S1 to S4.

  Next, the operation of the magnetic sensor 80 configured as described above will be described. As described above, since the switching element MS and the switching elements S1 to S4 of the current direction switching circuit are normally in the “off” state, the first and second inspection coils 91 and 92 have any magnetic field. Does not occur. In addition, since the switching element 93b is switched every elapse of a predetermined time, the resistance value indicated by the TMR element 81 or the resistance value indicated by the TMR element 82 is alternately converted (detected) into a digital value by the ADC 93a and converted. The value is used for detection of geomagnetism by the control circuit.

  Next, the operation when the predetermined condition is established and the magnetic sensor 80 is inspected will be described. In the magnetic sensor 80, in addition to the inspection of the TMR elements 81 and 82 for characteristic failure (whether the sensitivity is poor or whether the hysteresis is excessive), the first and second test coils 91, 92 are used. It is also determined whether or not the expected test magnetic field is generated (whether the detection circuit 93 and the current supply circuit 94 function normally). Hereinafter, the inspection procedure will be described by taking as an example a case where all of the TMR elements 81 and 82, the detection circuit 93, and the current supply circuit 94 of the magnetic sensor 80 operate normally.

(First procedure)
First, the control circuit 95 instructs the main switch MS to be in an “on” state, and instructs the switching devices S1 and S4 of the current direction switching circuit to be in an “on” state and the switching elements S3 and S2 to be in an “off” state. In addition, an instruction signal for selecting the TMR element 81 for the switching element 93b is supplied to each corresponding switching element.

  In this case, since all of them operate normally, the switching element MS is switched to the “on” state, and the switching elements S1 and S4 of the current direction switching circuit are switched to the “on” state, so that the switching element S3 , S2 are switched to the “off” state. Thereby, the current of the constant current source IS flows in the order of the switching element MS, the switching element S1, the second inspection coil 92, the first inspection coil 91, the switching element S4, and the identification current source IS. In the present specification, this state is also referred to as a state in which the instruction current for the first and second inspection coils is a positive current of a predetermined magnitude.

  In this case, the second inspection coil 92 applies a magnetic field having a magnitude of Hb in the Y-axis negative direction to the TMR element 82, and the first inspection coil 91 is in the X-axis positive direction and has a magnitude of Hb. Is applied to the TMR element 81. At this time, the TMR element 81 indicates a resistance having a resistance value Sx1, and the ADC 93a converts the resistance value of the TMR element 81 into a digital value. Therefore, as shown in FIG. 23A, the control circuit 95 acquires the resistance value Sx1 as the value X1 from the ADC 93a.

(Second procedure)
Next, the control circuit 95 supplies an instruction signal for turning the switching element MS to the “off” state to the switching element MS. As a result, since the switching element MS is switched from the “on” state to the “off” state, the first inspection coil 91 and the second inspection coil 92 are blocked from the current from the constant current source IS. De-energized. Therefore, the first and second inspection coils 91 and 92 do not generate any magnetic field.

  At this time, the TMR element 81 exhibits a resistance having a resistance value Sx2, and the ADC 93a converts the resistance value of the TMR element 81 into a digital value. Therefore, as shown in FIG. To obtain a resistance value Sx2 smaller than the resistance value Sx1 as a value X2.

(Third procedure)
Next, the control circuit 95 sets the main switch MS to the “ON” state again, sets the switching elements S1 and S4 of the current direction switching circuit to the “OFF” state, and sets the switching elements S3 and S2 to the “ON” state. The instruction signal to be supplied is supplied to each corresponding switching element.

  As a result, the switching element MS is switched to the “on” state, the switching elements S1 and S4 of the current direction switching circuit are switched to the “off” state, and the switching elements S3 and S2 are switched to the “on” state. It is done. Thereby, the current of the constant current source IS flows in the order of the switching element MS, the switching element S3, the first inspection coil 91, the second inspection coil 92, the switching element S2, and the identification current source IS. In this specification, this state is also referred to as a state in which the instruction current for the first and second inspection coils is a negative current having a predetermined magnitude.

  As a result, the first inspection coil 91 applies a magnetic field having a magnitude of Hb in the X-axis negative direction to the TMR element 81, and the second inspection coil 92 is in the Y-axis positive direction and has a magnitude of Hb. Is applied to the TMR element 82. At this time, the TMR element 81 indicates a resistance having a resistance value Sx3, and the ADC 93a converts the resistance value of the TMR element 81 into a digital value. Therefore, as shown in FIG. Obtains the resistance value Sx3 as the value X3 from the ADC 93a.

(4th procedure)
Next, the control circuit 95 supplies an instruction signal for turning the switching element MS to the “off” state to the switching element MS. As a result, since the switching element MS is switched from the “on” state to the “off” state, the first inspection coil 91 and the second inspection coil 92 are blocked from the current from the constant current source IS. De-energized. Therefore, the first and second inspection coils 91 and 92 do not generate any magnetic field.

  At this time, the TMR element 81 indicates a resistance having a magnitude Sx4 in the vicinity of the resistance value Sx2, and the ADC 93a converts the resistance value of the TMR element 81 into a digital value. Therefore, as shown in FIG. Acquires the resistance value Sx4 as the value X4 from the ADC 93a.

(5th procedure)
Next, the control circuit 95 instructs the main switch MS to be in the “on” state, instructs the switching elements S1 and S4 of the current direction switching circuit to be in the “on” state, and instructs signals to switch the switching elements S3 and S2 in the “off” state. In addition, an instruction signal for selecting the TMR element 82 for the switching element 93b is supplied to each corresponding switching element.

  Thereby, the current of the constant current source IS flows in the order of the switching element MS, the switching element S1, the second inspection coil 92, the first inspection coil 91, the switching element S4, and the identification current source IS. As a result, since the second inspection coil 92 applies a magnetic field having a magnitude of Hb in the negative Y-axis direction to the TMR element 82, the TMR element 82 exhibits a resistance having a resistance value Sy3, and the ADC 93a is a TMR element. The resistance value 82 is converted into a digital value. Therefore, as shown in FIG. 23B, the control circuit 95 acquires the resistance value Sy3 as the value Y1 from the ADC 93a.

(Sixth procedure)
Next, the control circuit 95 supplies an instruction signal for turning the switching element MS to the “off” state to the switching element MS. As a result, since the switching element MS is switched from the “on” state to the “off” state, the first inspection coil 91 and the second inspection coil 92 are blocked from the current from the constant current source IS. De-energized. Therefore, the first and second inspection coils 91 and 92 do not generate any magnetic field.

  At this time, since the ADC 93a converts the resistance value of the TMR element 82 into a digital value, as shown in FIG. 23B, the control circuit 95 obtains a resistance value Sy2 larger than the resistance value Sy3 from the ADC 93a as a value Y2. .

(Seventh procedure)
Next, the control circuit 95 sets the main switch MS to the “ON” state again, sets the switching elements S1 and S4 of the current direction switching circuit to the “OFF” state, and sets the switching elements S3 and S2 to the “ON” state. The instruction signal to be supplied is supplied to each corresponding switching element.

  As a result, the switching element MS is switched to the “on” state, the switching elements S1 and S4 of the current direction switching circuit are switched to the “off” state, and the switching elements S3 and S2 are switched to the “on” state. It is done. Accordingly, the second inspection coil 92 applies a magnetic field having a magnitude of Hb in the positive direction of the Y axis to the TMR element 82. At this time, the TMR element 82 shows a resistance having a resistance value Sy1, and the ADC 93a converts the resistance value of the TMR element 82 into a digital value. Therefore, as shown in FIG. Obtains the resistance value Sy1 as the value Y3 from the ADC 93a.

(8th procedure)
Next, the control circuit 95 supplies an instruction signal for turning the switching element MS to the “off” state to the switching element MS. As a result, since the switching element MS is switched from the “on” state to the “off” state, the first inspection coil 91 and the second inspection coil 92 are blocked from the current from the constant current source IS. De-energized. As a result, the first and second inspection coils 91 and 92 do not generate any magnetic field.

  At this time, the TMR element 82 indicates a resistance having a magnitude Sy4 in the vicinity of the resistance value Sy2, and the ADC 93a converts the resistance value of the TMR element 82 into a digital value. Therefore, as shown in FIG. The circuit 95 acquires the resistance value Sy4 as the value Y4 from the ADC 93a.

(Ninth procedure: Abnormal judgment step)
When the control circuit 95 obtains the values X1 to X4 and the values Y1 to Y4 by the above first to eighth procedures, it determines whether or not the following equations 3 to 6 are satisfied.
X1-X3 ≧ C1 (Equation 3)
| X2-X4 | <C2 ... Equation 4
Y3−Y1 ≧ C1 (Equation 5)
| Y2-Y4 | <C2.

  The value C1 in the above equations 3 and 5 is the maximum value (X1-X3) when the sensitivity of the TMR element 81 is insufficient and the value (Y3-Y1) when the sensitivity of the TMR element 82 is insufficient. ) Is selected to be larger than each of the maximum values. The value C2 in the above equations 4 and 6 is the minimum value of the value | X2-X4 | when the hysteresis of the TMR element 81 is excessive and the value | Y2-Y4 | when the hysteresis of the TMR element 82 is excessive. Is also chosen to be small. The values C1 and C2 are both positive values.

  At the present time, all of the TMR elements 81 and 82, the detection circuit 93, and the current supply circuit 94 of the magnetic sensor 80 are operating normally, and X1-X3 = Sx1-Sx3 ≧ C1, | X2-X4 | = | Sx2-Sx4 | <C2, Y3-Y1 = Sy3-Sy1 ≧ C1, and | Y2-Y4 | = | Sy2-Sy4 | <C2. That is, the above equations 3 to 6 are all established. Therefore, the control circuit 95 determines that all of the TMR elements 81 and 82, the detection circuit 93, and the current supply circuit 94 of the magnetic sensor 80 are normal.

  Next, a case where the sensitivity of the TMR element 81 is insufficient and the others are operating normally will be described. In this case, the TMR element 81 exhibits a value smaller than the resistance value Sx1 and larger than the resistance value Sx2 when a magnetic field having a magnitude of Hb is applied in the X-axis positive direction, and has a magnitude of Hb in the X-axis negative direction. When a magnetic field is applied, the value is larger than the resistance value Sx3 and smaller than the resistance value Sx2. For this reason, the control circuit 95 acquires the values X1 to X4 shown in FIG. 24A and the values Y1 to Y4 shown in FIG.

  In this case, the above formulas 4 to 6 hold, but the sensitivity of the TMR element 81 is insufficient, so the value (X1−X3) becomes small, and thus the above formula 3 does not hold. Based on this result, the control circuit 95 determines that an abnormality in which the sensitivity of the TMR element 81 is insufficient has occurred.

  Next, a case where the sensitivity of the TMR element 82 is insufficient and the others are operating normally will be described. In this case, the TMR element 82 exhibits a value smaller than the resistance value Sy1 and larger than the resistance value Sy2 when a magnetic field having a magnitude of Hb is applied in the Y-axis positive direction, and has a magnitude of Hb in the Y-axis negative direction. When a magnetic field is applied, the value is larger than the resistance value Sy3 and smaller than the resistance value Sy2. For this reason, the control circuit 95 acquires the values X1 to X4 shown in FIG. 25A and the values Y1 to Y4 shown in FIG.

  In this case, Equation 3, Equation 4, and Equation 6 hold, but since the sensitivity of the TMR element 82 is insufficient, the value (Y3-Y1) becomes small and Equation 5 does not hold. Based on this result, the control circuit 95 determines that an abnormality in which the sensitivity of the TMR element 82 is insufficient has occurred.

  Next, the case where the hysteresis of the TMR element 81 is excessive and the others are operating normally will be described. Such a TMR element 81 exhibits a value considerably larger than the resistance value Sx2 and smaller than the resistance value Sx1 when the magnetic field is extinguished after a magnetic field having a magnitude of Hb is applied in the positive direction of the X axis. When the magnetic field having a magnitude of Hb is applied in the negative direction and then disappears, the value is much smaller than the resistance value Sx2 and larger than the resistance value Sx3. For this reason, the control circuit 95 acquires the values X1 to X4 shown in FIG. 26A and the values Y1 to Y4 shown in FIG.

  In this case, Equation 3, Equation 5, and Equation 6 hold, but since the hysteresis of the TMR element 81 is excessive, the value | X2−X4 | increases and Equation 4 does not hold. Based on this result, the control circuit 95 determines that an abnormality in which the hysteresis of the TMR element 81 is excessive has occurred.

  Next, the case where the hysteresis of the TMR element 82 is excessive and the others are operating normally will be described. Such a TMR element 82 exhibits a value that is considerably smaller than the resistance value Sy2 and larger than the resistance value Sy3 when the magnetic field of magnitude Hb is applied in the negative direction of the Y-axis and then extinguished. When the magnetic field having a magnitude of Hb is applied in the positive direction and then disappears, the value is much larger than the resistance value Sy2 and smaller than the resistance value Sy1. For this reason, the control circuit 95 acquires the values X1 to X4 shown in FIG. 27A and the values Y1 to Y4 shown in FIG.

  In this case, Equations 3 to 5 are satisfied, but since the hysteresis of the TMR element 82 is excessive, the value | Y2−Y4 | becomes large and Equation 6 is not satisfied. Based on this result, the control circuit 95 determines that an abnormality in which the hysteresis of the TMR element 82 is excessive has occurred.

  Next, when the switching element MS functioning as a main switch is always in the “on” state and does not change to the “off” state, current flows in the first and second inspection coils 91 and 92. A description will be given of a case where an abnormality that continues to flow (however, the direction of the current flowing in the first and second inspection coils 91 and 92 can be switched) has occurred, but otherwise operates normally.

  Also in this case, the control circuit performs the above procedure 1 to procedure 8. When such an abnormal state occurs, in Step 1 and Step 2, a magnetic field having a constant magnitude Hb in the positive direction of the X axis is applied to the TMR element 81 by the first inspection coil 91. The value Sx1 is indicated. In steps 3 and 4, the TMR element 81 has a resistance value Sx3 because a magnetic field having a constant magnitude Hb in the negative direction of the X-axis is applied to the TMR element 81 by the first inspection coil 91. Similarly, in procedure 5 and procedure 6, since the magnetic field having a constant magnitude Hb in the negative Y-axis direction is applied to the TMR element 82 by the second inspection coil 92, the TMR element 82 exhibits a resistance value Sy3. In steps 7 and 8, a magnetic field having a constant magnitude Hb in the positive Y-axis direction is applied to the TMR element 82 by the second inspection coil 92, so that the TMR element 82 exhibits a resistance value Sy1. For this reason, the control circuit 95 acquires the values X1 to X4 shown in FIG. 28A and the values Y1 to Y4 shown in FIG.

  As a result, Equation 3 and Equation 5 hold, but since the value X2 has the same resistance value Sx1 as the value X1 and the value X4 has the same resistance value Sx3 as the value X3, the above Equation 4 does not hold. . Similarly, since the value Y2 becomes the same resistance value Sy3 as the value Y1 and the value Y4 becomes the same resistance value Sy1 as the value Y3, the above equation 6 is not satisfied. The control circuit 95 determines that an abnormality has occurred in the magnetic sensor 80 when such a result is obtained.

  Next, when the switching element MS functioning as the main switch is always in the “off” state and does not change to the “on” state, the first and second inspection coils 91 and 92 are disconnected, or the connection conductor A case will be described where 96a to 96c are disconnected, etc., and an abnormality in which current cannot flow through the first and second inspection coils 91 and 92 has occurred.

  Also in this case, the control circuit performs the procedure 1 to procedure 8 described above. When such an abnormal state occurs, the first and second inspection coils 91 and 92 do not generate any magnetic field in all of the procedures 1 to 8. Therefore, as shown in FIG. 29A, the values X1 to X4 are all the same resistance value Sx2, and as shown in FIG. 29B, the values Y1 to Y4 are all the same. The resistance value Sy2 is the same value. Therefore, the above equations 4 and 6 hold, but the above equations 3 and 5 do not hold. The control circuit 95 determines that an abnormality has occurred in the magnetic sensor 80 when such a result is obtained.

  Next, the switching elements S1 and S4 of the current direction switching circuit are always in the “on” state and do not change to the “off” state, and the switching elements S2 and S3 are always in the “off” state and change to the “on” state. A case will be described in which there is an abnormality in which the direction of the current flowing through the first and second inspection coils 91 and 92 cannot be changed.

  Also in this case, the control circuit performs the procedure 1 to procedure 8 described above. In such an abnormal state, in procedure 1 and procedure 3, currents having the same direction and the same magnitude flow in the first inspection coil 91, so that the TMR element 81 has a magnetic field of magnitude Hb in the positive direction of the X axis. Will be added. Therefore, as shown by the solid line in FIG. 30A, since the value X1 and the value X3 acquired by the control circuit 95 are the same resistance value Sx1, the above equation 4 is satisfied, but the above equation 3 is not satisfied. It becomes.

  Similarly, in steps 5 and 7, currents of the same magnitude in the same direction flow through the second inspection coil 92, so that a magnetic field of magnitude Hb is applied to the TMR element 82 in the negative Y-axis direction. Therefore, as indicated by the solid line in FIG. 30B, since the value Y1 and the value Y3 are the same value Sy3, the above equation 6 is satisfied, but the above equation 5 is not satisfied. The control circuit 95 determines that an abnormality has occurred in the magnetic sensor 80 when such a result is obtained.

  The switching elements S3 and S2 of the current direction switching circuit are always in the “on” state and do not change to the “off” state, and the switching elements S1 and S4 are always in the “off” state and do not change to the “on” state. In such a case, since the value X1 and the value X3 become the same resistance value Sx3, and the value Y1 and the value Y3 become the same resistance value Sy1, as shown by the broken lines in FIGS. Again, Equation 3 and Equation 5 are not established. Therefore, the control circuit 95 determines that an abnormality has occurred in the magnetic sensor 80 even when such a result is obtained.

  Next, the case where the switching element 93b of the detection circuit 93 always selects the TMR element 81 and an abnormality in which the TMR element 82 cannot be selected has occurred will be described.

  In such an abnormal state, the resistance value of the TMR element 81 is always detected, and the results of the procedure 5 to the procedure 8 are substantially the same as the results of the procedure 1 to the procedure 4. Therefore, FIGS. As shown in FIG. 5, the values X1 to X4 and the values Y1 to Y4 are substantially the same. That is, since the value Y1 is the same resistance value Sx1 as the value X1, and the value Y3 is the same resistance value Sx3 as the value X3, the value (Y3-Y1) is the same negative value as the value (X3-X1). Therefore, Equation 3, Equation 4, and Equation 6 hold, but Equation 5 does not hold. When such a result is obtained, the control circuit 95 determines that an abnormality has occurred in the magnetic sensor 80 (detection circuit 93).

  Similarly, a case will be described in which the switching element 93b of the detection circuit 93 always selects the TMR element 82, and an abnormality has occurred in which the TMR element 81 cannot be selected.

  In such an abnormal state, the resistance value of the TMR element 82 is always detected, and the results of Procedure 1 to Procedure 4 are substantially the same as the results of Procedure 5 to Procedure 8, so FIGS. 32 (A) and 32 (B) As shown in FIG. 5, the values X1 to X4 and the values Y1 to Y4 are substantially the same. That is, since the value X1 is the same resistance value Sy3 as the value Y1, and the value X3 is the same resistance value Sy1 as the value Y3, the value (X1-X3) is the same negative value as the value (Y1-Y3). Therefore, Equation 4 to Equation 6 are satisfied, but Equation 3 is not satisfied. When such a result is obtained, the control circuit 95 determines that an abnormality has occurred in the magnetic sensor 80 (detection circuit 93).

(10th procedure: balance determination step)
Finally, when the control circuit 95 determines that no abnormality has occurred in the procedure so far, the control circuit 95 determines whether or not the characteristics of the TMR element 81 and the TMR element 82 are balanced. 7. It is determined whether Equation 8 is satisfied. The value C3 is a positive predetermined value.
| X1-Y3 | <C3 ... Equation 7
| X3-Y1 | <C3 ... Equation 8

  When either of the above formulas 7 and 8 does not hold, the control circuit 95 determines that an abnormality has occurred in which the outputs of the TMR element 81 and the TMR element 82 are not balanced.

  As described above, according to the magnetic sensor 80 according to the fourth embodiment, the first inspection coil 91 and the second inspection coil 92 are provided in the chip (substrate 80a), and the TMR element 81 is provided. , 82 can be provided with a magnetic field for inspection, so that the inspection device of the magnetic sensor 80 does not need to have a magnetic field generating function.

  Further, according to the magnetic sensor 80, the first inspection coil 91 and the second inspection coil 92 are connected in series to the constant current source IS that is a current supply source, and function as an energization control circuit. Since the element MS and the switching elements S1 to S4 are interposed in the closed circuit, even if characteristics such as resistance values of the switching elements MS and S1 to S4 vary, the first and second inspection coils 91 are provided. , 92 can be supplied with the same current. Therefore, it is possible to apply a magnetic field of the same magnitude to the TMR elements 81 and 82. For example, by making the determinations of the above formulas 7 and 8, that is, based on the resistance values exhibited by the TMR elements 81 and 82. Thus, it is possible to determine whether or not the output of both elements is balanced.

  Furthermore, according to the magnetic sensor 80 according to the fourth embodiment, since the detection circuit 93 selects one of the TMR elements 81 and 82 and performs AD conversion, the ADC 93a is an inexpensive and small one channel. Since it is possible to employ an ADC and to determine whether or not the selection function of the detection circuit 93 (the switching element 93b) is normal, it is possible to provide a highly reliable magnetic sensor 80. .

  Further, as described above, since the magnetic sensor according to each embodiment of the present invention employs a double spiral coil, it can generate a necessary magnetic field for each while being small in size and low in power consumption. Can do.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, the magnetic sensor 60 of the third embodiment employs a GMR element, but a TMR element may be employed instead of the GMR element. The magnetic sensor 80 according to the fourth embodiment employs the TMR elements 81 and 82. However, instead of the TMR elements 81 and 82, other magnetoresistive elements such as a GMR element may be employed. Or you may employ | adopt the magnetic detection part comprised by these magnetoresistive effect elements being distributed and arrange | positioned on a board | substrate, and being connected by a connection conducting wire in the shape of a bridge circuit. Furthermore, any two or more of the initialization coil, the bias magnetic field coil, and the inspection coil may be stacked and incorporated in the substrate of each magnetic sensor.

  In each of the above embodiments, the initialization coil, the bias magnetic field coil, and the inspection coil are formed in the same substrate (in the same chip) as the substrate on which the TMR element and the GMR element are formed. The coils may be formed in a substrate separate from the substrate on which these elements are formed, and the substrate on which the elements are formed and the substrate on which the coils are formed may be in close contact with each other.

1 is a schematic plan view of a magnetic sensor according to a first embodiment of the present invention. FIG. 2 is a partially enlarged plan view of a magnetic tunnel effect element (group) and a bias magnetic field coil of the magnetic sensor shown in FIG. 1. It is sectional drawing which cut | disconnected the magnetic tunnel effect element and the coil for bias magnetic fields in the plane along the 1-1 line | wire of FIG. It is sectional drawing which cut | disconnected the magnetic tunnel effect element and the coil for bias magnetic fields in the plane in alignment with line 2-2 of FIG. 2 is a graph showing a magnetization curve of a sense layer of the magnetic tunnel effect element shown in FIG. 1. 2 is a graph showing a magnetization curve of a reference layer of the magnetic tunnel effect element shown in FIG. 1. It is a graph which shows MR curve (change of resistance with respect to a magnetic field) of the magnetic tunnel effect element shown in FIG. 2 is a graph showing an AC bias magnetic field applied to the magnetic tunnel effect element shown in FIG. 1. It is a graph which shows the change of the resistance of the element at the time of applying the alternating current bias magnetic field shown in FIG. 8 to the magnetic tunnel effect element shown in FIG. 1, and changing the external magnetic field which should be detected. It is a graph which shows the change of the detected value with respect to the external magnetic field which should detect the magnetic tunnel effect element shown in FIG. It is a schematic plan view of the magnetic sensor which concerns on 2nd Embodiment of this invention. FIG. 12 is a partially enlarged plan view of the GMR element and coil of the magnetic sensor shown in FIG. 11. It is a top view of the GMR element shown in FIG. It is the schematic sectional drawing which cut | disconnected the GMR element and the coil in the plane in alignment with the 3-3 line of FIG. It is a figure which shows the spin valve film | membrane structure of the GMR element shown in FIG. 13 is a graph showing changes in resistance value with respect to an external magnetic field of the GMR element shown in FIG. 12. FIG. 13 is an equivalent circuit diagram of an X-axis magnetic sensor included in the magnetic sensor shown in FIG. 12. 18 is a graph showing changes in an output voltage (solid line) with respect to an external magnetic field changing in the X-axis direction and an output voltage (broken line) with respect to a magnetic field changing in the Y-axis direction of the X-axis magnetic sensor shown in FIG. It is a schematic plan view of the magnetic sensor which concerns on 3rd Embodiment by this invention. It is a schematic plan view of the magnetic sensor which concerns on 4th Embodiment by this invention. It is the graph which showed the resistance value characteristic of the TMR element of the 1st magnetic detection part shown in FIG. It is the graph which showed the resistance value characteristic of the TMR element of the 2nd magnetic detection part shown in FIG. It is the graph which showed the detected value which a control circuit acquires when the magnetic sensor shown in Drawing 20 is normal. It is the graph which showed the detected value which a control circuit acquires when the sensitivity of the 1st magnetic detection part of the magnetic sensor shown in Drawing 20 is insufficient. It is the graph which showed the detection value which a control circuit acquires when the sensitivity of the 2nd magnetic detection part of the magnetic sensor shown in FIG. 20 is insufficient. It is the graph which showed the detected value which a control circuit acquires when the hysteresis of the 1st magnetic detection part of the magnetic sensor shown in FIG. 20 is excessive. It is the graph which showed the detected value which a control circuit acquires when the hysteresis of the 2nd magnetic detection part of the magnetic sensor shown in FIG. 20 is excessive. FIG. 21 is a graph showing detection values acquired by the control circuit when there is an abnormality in which the magnitude of the current flowing through the test coil of the magnetic sensor shown in FIG. 20 cannot be changed (the current for inspection cannot be interrupted). It is the graph which showed the detected value which a control circuit acquires when abnormality which cannot flow an electric current has arisen in the coil for a test of the magnetic sensor shown in FIG. It is the graph which showed the detected value which a control circuit acquires when abnormality which the direction of the electric current which flows into the coil for a test of the magnetic sensor shown in Drawing 20 cannot change is generated. FIG. 21 is a graph showing detection values acquired by the control circuit when there is an abnormality in which the detection circuit always selects the first magnetic detection unit in the magnetic sensor shown in FIG. 20. FIG. 21 is a graph showing detection values acquired by the control circuit when there is an abnormality in which the detection circuit always selects the second magnetic detection unit in the magnetic sensor shown in FIG. 20. It is the elements on larger scale of the magnetic tunnel effect element (group) of the conventional magnetic sensor, and the coil for bias magnetic fields.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Magnetic sensor, 10a ... Board | substrate, 11, 12 ... Magnetic tunnel effect element 21, 21-1 ... 1st conducting wire part, 21-2 ... 2nd conducting wire part, P1, P2 ... Vortex center.

Claims (2)

A pinned layer including a pinned layer whose magnetization direction is fixed, a thin-film giant magnetoresistive element including a conductive spacer layer and a free layer;
A magnetic sensor including a coil that is formed in a plane parallel to the film plane of the giant magnetoresistive element and generates a magnetic field applied to the magnetoresistive element;
In order to stabilize the magnetization direction of the free layer in a state where an external magnetic field is not applied to the giant magnetoresistive effect element, the giant magnetoresistive effect element is disposed at both ends of the giant magnetoresistive effect element and is uniaxial to the free layer. A bias magnet film that generates a magnetic field in the same direction as the direction of magnetization due to anisotropy,
The coil is
A first conductor that forms a spiral in plan view and a second conductor that forms a spiral in plan view;
The giant magnetoresistive element is disposed between the vortex center of the first conductor and the vortex center of the second conductor in plan view,
The first conductive wire portion located in a portion overlapping the giant magnetoresistive effect element in plan view and the second lead wire portion located in a portion overlapping the giant magnetoresistive effect element in plan view are substantially in the same direction. The first conductor and the second conductor are connected so that the current flows, and the widths of the first and second conductors located in a portion overlapping the giant magnetoresistive element in plan view Is formed so as to be narrower than the respective widths of the first and second conducting wires located in other parts,
A magnetic sensor which is a coil that initializes the magnetization direction of the free layer by generating a magnetic field in the same direction as the magnetization direction due to uniaxial anisotropy of the free layer. The magnetic sensor according to claim 1,
The portion of the first conducting wire positioned in a portion overlapping the giant magnetoresistive effect element in plan view and the portion of the second conducting wire located in a portion overlapping the giant magnetoresistive effect element in plan view are parallel to each other. A magnetic sensor formed in a straight line.

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