Magnetic sensor and current sensor using magnetoresistive element

Abstract

The magnetic sensor (13) comprises: a magnetic field detection unit (122) composed of magnetoresistance effect elements (122a to 122d), a feedback coil (121) and a shield (124). The feedback coil (121) and the magnetic field detection unit (122) are arranged to overlap, and the shield (124) and the feedback coil (121) are arranged to overlap, so that it is difficult to be magnetically saturated due to the offset magnetic field of the feedback coil (121). The shield (124) is annular in shape when viewed from its normal direction, so that the magnetic field shielding effect of the shield (124) can be maintained, thereby improving the effect of shielding the magnetic field in the direction orthogonal to the sensitivity.

Description

Technical Field

[0001] The present invention relates to a magnetic sensor and a current sensor having a feedback coil and a shield and using a magnetoresistive effect element. Background Art

[0002] In the fields of motor drive technology such as electric vehicles, relatively large currents are used, so sensors that can measure large currents without contact are needed. And as such a sensor, a current sensor that detects the change in the magnetic field generated by the current being measured by a magnetic sensor has been put into practical use. In the current sensor of this type, in order to reduce the external magnetic field to which the magnetic sensor is subjected, a component that serves as a shield for the external magnetic field is sometimes provided. By providing such a shield, the orthogonal magnetic field resistance to the magnetic field in the direction orthogonal to the sensitivity is improved. In addition, the magnetic field strength to which the magnetic sensor is subjected becomes smaller, and the upper limit of the magnetic field strength that can actually be measured becomes higher, which can expand the measurable range (dynamic range) of the current sensor.

[0003] Patent document 1 describes a current sensor having a magnetoresistance effect element, a magnetic shield, and a feedback coil for the purpose of reducing an external magnetic field and suppressing the influence of hysteresis, wherein the magnetic shield is constructed to include a flat-plate-shaped first magnetic shield and a flat-plate-shaped second magnetic shield arranged separately from the first magnetic shield in the in-plane direction of a main surface of the first magnetic shield.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-53903 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In the current sensor of Patent Document 1, in order to suppress the influence of the closed magnetic field generated by the residual magnetization of the first magnetic shield on the magnetoresistive effect element, a second magnetic shield is arranged on both sides of the sensitivity direction of the first magnetic shield. However, since the second magnetic shield is arranged at a position that does not overlap with the feedback coil, it is impossible to suppress the magnetic saturation of the second magnetic shield using the magnetism from the feedback coil. If the second magnetic shield is magnetically saturated, it is impossible to reduce the interference magnetic field (interference magnetic field), so the shielding effect of the magnetic field in the orthogonal direction of the sensitivity and the effect of increasing the anisotropic magnetic field of the first magnetic shield are insufficient.

[0009] An object of the present invention is to provide a magnetic sensor and a current sensor which are effective in shielding a magnetic field in a direction orthogonal to the sensitivity and have excellent resistance to orthogonal magnetic fields.

[0010] Another object of the present invention is to provide a magnetic sensor and a current sensor having a large anisotropic magnetic field and a wide measurable range and a shield that weakens the intensity of a magnetic field to be measured applied to a magnetic field detection unit.

[0011] Solutions for solving problems

[0012] The magnetic sensor of the present invention is a magnetic sensor comprising a magnetic field detection unit formed by a magnetoresistive effect element, a feedback coil and a shielding member, and is characterized in that the feedback coil is arranged to overlap with the magnetic field detection unit, the shielding member is arranged to overlap with the feedback coil, and the shielding member has a ring-shaped shape when viewed from its normal direction.

[0013] Since the shield is arranged to overlap the feedback coil, the shield is less likely to be magnetically saturated by canceling the magnetic field. Therefore, the magnetic field shielding effect of the shield can be maintained, and the orthogonal magnetic field resistance of the magnetic sensor can be improved.

[0014] The magnetic sensor of the present invention is a magnetic sensor including a magnetic field detection unit formed of a magnetoresistive effect element, a feedback coil, and a shield, and is characterized in that the feedback coil is arranged to overlap with the magnetic field detection unit, the shield is arranged to overlap with the feedback coil, and the shield has: an inner shield arranged to weaken the intensity of the magnetic field to be measured applied to the magnetic field detection unit; and an outer shield arranged to weaken the intensity of the magnetic field to be measured applied to the inner shield.

[0015] The magnetic field to be measured from the sensitivity direction is shielded by the outer shield, so the magnetic field applied to the inner shield becomes smaller. By reducing the applied magnetic field, the saturation magnetic field becomes larger, so the anisotropic magnetic field (hereinafter appropriately referred to as "Hk") on the surface of the inner shield can be increased. That is, by providing the outer shield to reduce the effective magnetic field applied to the inner shield, the Hk of the inner shield on the surface can be increased without substantially changing the Hk of the inner shield. The Hk of the inner shield becomes larger when viewed from the surface, thereby widening the range in which the magnetic permeability (μ) of the inner shield is constant, and thus, a magnetic sensor with a wide measurable range can be provided.

[0016] Furthermore, since the outer shield overlaps the feedback coil, the outer shield is less likely to be magnetically saturated using a canceling magnetic field. This maintains the magnetic field shielding effect of the outer shield to reduce the magnetic field reaching the inner shield, thereby increasing Hk on the surface of the inner shield.

[0017] Preferably, in the inner shield, the direction of the measured magnetic field is the same as the direction of the cancelling magnetic field of the feedback coil, and in the outer shield, a portion is provided where the direction of the measured magnetic field is opposite to the direction of the cancelling magnetic field of the feedback coil.

[0018] With the above configuration, the inner shield functions as a yoke that strengthens the cancelling magnetic field, thereby reducing the current flowing to the feedback coil. In addition, since the effective magnetic field applied to the outer shield can be reduced by the cancelling magnetic field, the magnetic field shielding effect of the outer shield can be improved.

[0019] Preferably, the feedback coil includes a first coil portion and a second coil portion, and the first coil portion and the second coil portion are configured to be line symmetrical about an imaginary center line orthogonal to the sensitivity direction of the magnetoresistance effect element when viewed from the normal direction of the inner shield.

[0020] In this case, the magnetic field detection unit is a full-bridge circuit in which the four magnetoresistive effect elements are arranged, and the four magnetoresistive effect elements are preferably provided so as to overlap the virtual center line when viewed in a normal direction of the inner shield.

[0021] By forming the feedback coil with two coil parts arranged in line symmetry, when the external magnetic shield is arranged to overlap the feedback coil along the outer periphery of the feedback coil, the feedback coil and the shield can be arranged in line symmetry with respect to the imaginary center line. Therefore, by the full-bridge circuit arranged to overlap the imaginary center line, it is possible to obtain an output symmetrical with respect to the sensitivity direction on the positive magnetic field side and the negative magnetic field side.

[0022] Preferably, the outer shield is formed to surround the inner shield. Preferably, the inner shield has a substantially rectangular shape when viewed from its normal direction. Here, the so-called "substantially rectangular" includes a quadrangle and a rounded quadrangle with rounded corners. From a manufacturing point of view, a rounded quadrangle with R at the corner (the corner is not a right angle) is more preferred.

[0023] According to the above configuration, the shielding property of the magnetic field by the outer shield is improved, so that Hk on the surface of the inner shield can be increased and the measurable range of the magnetic sensor can be expanded.

[0024] Preferably, the outer shield is formed into a ring shape. By forming the ring shape, the outer shield is provided in a direction perpendicular to the sensitivity direction in addition to the sensitivity direction based on the inner shield, so that the orthogonal magnetic field resistance to the disturbance magnetic field from the direction perpendicular to the sensitivity direction can be enhanced.

[0025] The width of the outer shield may be less than or equal to the width of the inner shield.

[0026] By setting the width of the outer shield to be less than or equal to the width of the inner shield, the saturation magnetic field of the outer shield can be made larger than the saturation magnetic field of the inner shield.

[0027] A current sensor according to the present invention is characterized by including the magnetic sensor according to the present invention.

[0028] Effects of the Invention

[0029] The magnetic sensor of the present invention includes the annular shield arranged to overlap the feedback coil, and therefore the shield is less likely to be magnetically saturated by canceling the magnetic field, thereby improving the orthogonal magnetic field resistance of the magnetic sensor.

[0030] In the magnetic sensor of the present invention, the shield has an inner shield and an outer shield, and is configured so that the outer shield weakens the intensity of the magnetic field to be measured applied to the inner shield, so that Hk on the surface can be increased without weakening the magnetic field shielding effect of the inner shield. Therefore, it is possible to provide a magnetic sensor and a current sensor that are excellent in resistance to disturbance magnetic fields and have a wide measurable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram showing the structure of a current sensor including the magnetic sensor according to the first embodiment.

[0032] Figure 2 (a) A plan view of a magnetic field detection unit, (b) a plan view of a feedback coil, and (c) a plan view of a shield of the magnetic sensor according to the first embodiment.

[0033] Figure 3 It is a plan view showing the structure of the magnetic sensor according to the first embodiment.

[0034] Figure 4 This is a partially enlarged view of the magnetoresistive effect element according to the first embodiment.

[0035] Figure 5 for Figure 3 (a) Top view of the PP cross section, (b) Top view of the Q1Q1 cross section, and (c) Schematic diagram of the R1R1 cross section of the magnetic sensor.

[0036] Figure 6 (a) is a schematic diagram showing a magnetic field around an annular outer shield, and (b) is a schematic diagram showing a magnetic field detector, a feedback coil, and a shield according to the first embodiment.

[0037] Figure 7(a) is a graph schematically showing the relationship between the width of the inner shield and the anisotropic magnetic field (Hk), and (b) is a graph schematically showing the relationship between the thickness of the inner shield and the anisotropic magnetic field (Hk).

[0038] Figure 8 It is a plan view showing the structure of a magnetic sensor according to a modification example of the first embodiment.

[0039] Fig. 9 It is a top view showing the structure of the magnetic sensor of Comparative Example 1.

[0040] Fig.10 This is a graph schematically showing the linear calculation method of Examples 1 and 2.

[0041] Fig.11 This is a graph showing the results of evaluating the linearity of the magnetic sensors of Examples 1 and 2 and Comparative Example 1.

[0042] Fig.12 (a) A plan view of a magnetic field detection unit, (b) a plan view of a feedback coil, and (c) a plan view of a shield of the magnetic sensor according to the second embodiment.

[0043] Fig.13 It is a plan view showing the structure of the magnetic sensor according to the second embodiment.

[0044] Fig.14 for Fig.13 Schematic diagram of the (a) PP cross section, (b) Q1Q1 cross section, and (c) R1R1 cross section of the magnetic sensor.

[0045] Fig.15 (a) is a schematic diagram showing a magnetic field around a ring-shaped shield, and (b) is a schematic diagram showing a magnetic field detector, a feedback coil, and a shield according to the second embodiment.

[0046] Fig.16 It is a top view showing the structure of the magnetic sensor of Comparative Example 2.

[0047] Fig.17 This is a graph showing the external magnetic field resistance of the magnetic sensor of Example 3.

[0048] Fig.18 This is a graph showing the external magnetic field resistance of the magnetic sensor of Comparative Example 2.

[0049] Fig.19 It is a cross-sectional view schematically showing the stacked structure of the GMR element.

[0050] Fig. 20 It is a diagram for explaining the offset of the resistance of the free magnetic layer caused by magnetic hysteresis. DETAILED DESCRIPTION

[0051] The embodiments of the present invention are described below with reference to the drawings. In each of the drawings, the same reference numerals are given to the same components, and the description thereof will be appropriately omitted.

[0052] (First Embodiment)

[0053] Figure 1 FIG. 1 is a schematic diagram schematically showing the structure of a magnetic balance type current sensor including the magnetic sensor 12 of this embodiment. Figure 1 1, the connection relationship of the magnetoresistive effect elements 122a to 122d and the like constituting the magnetic field detection unit 122 of the magnetic sensor 12 is mainly shown, and the specific structure, configuration, positional relationship of the feedback coil and the shielding member are shown in FIG. Figure 2 It will be described later.

[0054] like Figure 1 As shown, the magnetic sensor 12 is arranged near the conductor (current line) 11 through which the current I to be measured flows. The magnetic sensor 12 includes a feedback circuit for generating a canceling magnetic field B that cancels the induced magnetic field A generated by the current I.

[0055] The feedback coil 121 is formed of a spiral planar wiring pattern, and can generate a canceling magnetic field B in the opposite direction to the induced magnetic field A by flowing a current through the wiring pattern.

[0056] The magnetoresistance effect elements 122a to 122d of the magnetic field detection unit 122 are elements whose resistance value changes when an external magnetic field is applied. As such elements, GMR (Giant Magneto Resistance) elements, TMR (Tunnel Magneto Resistance) elements, etc. can be used. In the magnetic sensor 12 of the present embodiment, the magnetoresistance effect elements 122a to 122d are connected in a prescribed relationship, thereby forming a magnetic field detection bridge circuit that detects changes in the external magnetic field. By using a magnetic field detection bridge circuit including the magnetoresistance effect elements 122a to 122d, it is possible to realize a magnetic sensor 12 that can detect the induced magnetic field A of the measurement object generated by the current I with high sensitivity. In addition, the magnetic field detection bridge circuit is not limited to Figure 1 The magnetic field detection bridge circuit can be configured to include a fixed resistor element whose resistance value does not change due to an external magnetic field. The magnetic sensor 12 can measure the current by measuring the induced magnetic field A, so the magnetic sensor 12 is also a current sensor that measures the current I.

[0057] In the magnetic field detection bridge circuit of the magnetic field detection unit 122, a power supply for supplying power supply voltage Vdd is connected to the connection point between the magnetoresistance effect element 122b and the magnetoresistance effect element 122c. In addition, a ground line for supplying ground voltage GND is connected to one end of the magnetoresistance effect element 122a and one end of the magnetoresistance effect element 122d. A first output voltage Out1 is taken from the connection point between the magnetoresistance effect element 122a and the magnetoresistance effect element 122b, and a second output voltage Out2 is taken from the connection point between the magnetoresistance effect element 122c and the magnetoresistance effect element 122d. The voltage difference between the two outputs corresponds to the external magnetic field applied to the magnetoresistance effect elements 122a to 122d.

[0058] The voltage difference between the first output voltage Out1 and the second output voltage Out2 is amplified by the amplifier 123 and supplied to the feedback coil 121 as a current (feedback current). That is, the feedback current has a magnitude corresponding to the voltage difference between the first output voltage Out1 and the second output voltage Out2. When the feedback current flows through the feedback coil 121, a canceling magnetic field B is generated around the feedback coil 121 in a manner that cancels the induced magnetic field A detected by the magnetic field detection unit 122. When the magnetic field strength of the induced magnetic field A is strong, the voltage difference of the magnetic field detection bridge circuit becomes large, and the feedback current flowing through the feedback coil 121 becomes large, so the canceling magnetic field B also becomes large. When the magnetic field strength of the induced magnetic field A is weak, the voltage difference of the magnetic field detection bridge circuit becomes small, and the feedback current flowing through the feedback coil 121 becomes small, so the canceling magnetic field B also becomes small. In this way, the feedback coil 121 generates a canceling magnetic field B that cancels the induced magnetic field A. Then, based on the current value of the feedback current in the equilibrium state where the induced magnetic field A and the canceling magnetic field B cancel each other, the induced magnetic field A and the current I are calculated at the detection resistor R as the detection unit.

[0059] Figure 2 (a) Figure 2 (b) and Figure 2 (c) is a plan view of the magnetic field detection unit 122 , the feedback coil 121 , and the shield 124 of the magnetic sensor 12 according to the present embodiment.

[0060] Figure 3 This is a top view for explaining the structure of the magnetic sensor 12 according to the embodiment, schematically showing Figure 2 (a)~ Figure 2 (c) shows the positional relationship of the components in a stacked state.

[0061] As shown in these figures, the magnetic sensor 12 of the present embodiment includes a magnetic field detection unit 122 including magnetoresistance effect elements 122 a to 122 d , a feedback coil 121 , and a shield 124 .

[0062] like Figure 2As shown in (a), the magnetic field detection unit 122 includes a magnetic field detection bridge circuit composed of magnetoresistive effect elements 122a to 122d. Figure 2 In (a), the magnetization direction of the PIN layer when GMR is used as each of the magnetoresistance effect elements 122a to 122d is indicated by an arrow, and the magnetization direction of the free magnetic layer is indicated by a hollow arrow. Figure 2 The magnetic field detector 122 shown in (a) has a sensitivity direction for detecting magnetism in the Y1Y2 direction. In addition, four magnetoresistive effect elements 122a to 122d are arranged in a straight line in the X1X2 direction.

[0063] Figure 4 FIG. 1 is a partially enlarged view showing the magnetoresistance effect elements 122a to 122d according to the embodiment. Figure 4 As shown, the magnetoresistive effect elements 122a to 122d include a magnetic field detection pattern in which a plurality of long patterns 31 are arranged substantially parallel to the direction (Y1Y2 direction) perpendicular to the long dimension direction (X1X2 direction) of the long pattern 31. Figure 4 In FIG. 1 , the sensitivity direction (direction S) is a direction perpendicular to the longitudinal direction of the long pattern 31. Therefore, the magnetoresistive effect elements 122a to 122b are

[0064] 122d is arranged so that the directions of the induced magnetic field A and the canceling magnetic field B received by the magnetoresistance effect elements 122a to 122d coincide with the direction S. Figure 4 3 shows a magnetic field detection pattern including seven long strip patterns 31 a to 31 g , but the number of the long strip patterns 31 is not limited thereto.

[0065] In the arrangement direction of the long strip patterns 31, one end portion ( Figure 4 On the other hand, in the arrangement direction of the long strip pattern 31a, the other end ( Figure 4 The right end portion shown in the figure) is connected to the connection terminal 32b.

[0066] The other end of the strip pattern 31a is connected to the other end of the strip pattern 31b adjacent to the strip pattern 31a through a connecting portion 33a, and one end of the strip pattern 31b is connected to one end of the strip pattern 31c adjacent to the strip pattern 31b through a connecting portion 33b. Similarly, the other end of the strip pattern 31c is connected to the end of the adjacent strip pattern 31d through a connecting portion 33c, and one end of the strip pattern 31d is connected to one end of the adjacent strip pattern 31e through a connecting portion 33d. In this way, the ends of the strip pattern 31 are connected to the adjacent strip pattern 31 through connecting portions 33a to 33f, thereby forming a meander-shaped magnetic field detection pattern.

[0067] If a current flows between a power supply (power supply voltage Vdd) and a ground line (ground voltage GND) through the above-mentioned meander-shaped magnetic field detection pattern, a voltage drop occurs in the meander-shaped magnetic field detection pattern in accordance with its resistance value. The resistance value of the meander-shaped magnetic field detection pattern changes due to the external magnetic field, and therefore, the voltage drop in the magnetic field detection pattern changes in accordance with the induced magnetic field A and the offset magnetic field B. One of the connection terminals 32a and 32b of the magnetic field detection pattern is connected to one of the first output terminal or the second output terminal via wiring or the like. Thus, a voltage value corresponding to the voltage drop generated in the magnetic field detection pattern can be obtained as the first output voltage Out1 or the second output voltage Out2.

[0068] like Figure 3 As shown in FIG. 1 , a feedback coil 121 having a spiral wiring pattern is formed above the magnetoresistive effect elements 122a to 122d (near the paper, in the Z1 direction) via an insulating film or the like. The wiring pattern of the feedback coil 121 is arranged so that a portion of the wiring pattern of the feedback coil 121 is connected to a portion of the wiring pattern of the feedback coil 121 when viewed from above in the Z2 direction (in the back of the paper, in the Z2 direction, see FIG. 1 ). Figure 5 (a)) overlaps with the magnetoresistance effect elements 122a~122d. In the area overlapping with the magnetoresistance effect elements 122a~122d, the wiring pattern of the feedback coil 121 is set to extend approximately parallel to the extension direction of the long pattern (X1X2 direction). As a result, the feedback coil 121 can generate a canceling magnetic field B in a direction (Y1Y2 direction) approximately perpendicular to the extension direction of the long pattern. That is, in the area overlapping with the magnetoresistance effect elements 122a~122d, the direction of the canceling magnetic field B received by the magnetoresistance effect elements 122a~122d is consistent with the sensitivity direction of the magnetoresistance effect elements 122a~122d. In addition, in the magnetic sensor 12, the specific structure of the feedback coil 121 is not limited to Figure 2 (b) Figure 3 The composition shown.

[0069] like Figure 3 As shown, the feedback coil 121 is arranged to overlap with the magnetic field detector 122. Here, "overlappingly arranged" means that when viewed from the normal direction of the inner shield 124a, that is, when viewed from the Z1 direction to the Z2 direction, a part of the feedback coil 121 is arranged to overlap with the magnetic field detector 122.

[0070] In addition, if Figure 2As shown in (b), the feedback coil 121 includes a first coil portion 121a and a second coil portion 121b. The first coil portion 121a and the second coil portion 121b are configured so that their shapes when viewed from the normal direction of the inner shield 124a are line-symmetrical across an imaginary center line CL orthogonal to the Y1Y2 direction, which is the sensitivity direction of the magnetoresistance effect elements 122a to 122d. In addition, near the region overlapping the magnetoresistance effect elements 122a to 122d, the currents flowing through the first coil portion 121a and the second coil portion 121b are in the same direction, so the directions of the canceling magnetic fields B generated by the first coil portion 121a and the second coil portion 121b are in the same direction.

[0071] like Figure 2 As shown in (c), the shield 124 includes an inner shield 124a having a substantially rectangular shape when viewed from the normal direction (Z1 direction) thereof, and an outer shield 124b having a ring shape surrounding the inner shield 124a.

[0072] like Figure 3 As shown, the flat plate-shaped inner shield 124a formed in the XY plane is arranged to cover the magnetoresistance effect elements 122a to 122d of the magnetic field detection unit 122 when viewed from the normal direction (Z1 direction) of the inner shield 124a toward the Z2 direction. Therefore, the intensity of the induced magnetic field A from the current I applied to the magnetic field detection unit 122 can be weakened by the inner shield 124a.

[0073] The outer shield 124b is arranged to overlap the feedback coil 121 along the outer circumference of the feedback coil 121 so as to surround the inner shield 124a when viewed from the normal direction of the inner shield 124a. In addition, the inner shield 124a and the outer shield 124b are arranged on the same plane. The inner shield 124a and the outer shield 124b can be formed by the same process using a high magnetic permeability material or the like. In this case, the inner shield 124a and the outer shield 124b can also be set to the same thickness.

[0074] The outer shield 124b is provided on the feedback coil 121 in an overlapping manner, so that the saturation magnetic field can be increased by canceling the magnetic field as described later. In addition, for the shield 124, the width W2 of the outer shield 124b is made smaller than the width W1 of the inner shield 124a, thereby making the saturation magnetic field of the outer shield 124b larger than the saturation magnetic field of the inner shield 124a. As a result, the anisotropic magnetic field on the surface of the inner shield 124a becomes larger. In addition, the width W1 of the inner shield 124a refers to the distance in the short dimension direction of the rectangle, and the width W2 of the outer shield 124b refers to the width of the ring. In the present embodiment, the width W1 and the width W2 are both the lengths in the sensitivity direction (Y1Y2 direction) of the magnetic field detection unit 122.

[0075] The feedback coil 121 is arranged so that the first coil portion 121a and the second coil portion 121b are line-symmetrical with respect to the imaginary center line CL. Thus, it is easy to arrange the outer shield 124b along the outer periphery of the feedback coil 121 when viewed from the normal direction of the inner shield 124a, that is, it is easy to arrange so that the outer shield 124b overlaps the outer periphery (outer contour) of the feedback coil 121 when viewed from the stacking direction (Z1Z2 direction).

[0076] The configuration in which the outer shield 124b of the shield 124 is arranged to overlap the feedback coil 121 can increase the saturation magnetic field of the outer shield 124b using the canceling magnetic field. Therefore, the magnetic field applied to the inner shield 124a can be effectively reduced by the outer shield 124b, so that Hk on the surface of the inner shield 124a can be increased.

[0077] In the region overlapping the magnetoresistance effect elements 122a to 122d, an inner shield 124a is provided above the feedback coil 121 (toward the front of the drawing, in the Z1 direction). Also, an outer shield 124b is provided around the inner shield 124a and is disposed separately from the inner shield 124a.

[0078] The outer shield 124b is disposed in an annular shape around the inner shield 124a. That is, the outer shield 124b and the inner shield 124a are in the direction of the induced magnetic field A and the canceling magnetic field B (see Figure 1 , Y1Y2 direction) that is, the sensitivity direction of the magnetoresistance effect elements 122a to 122d and the direction orthogonal thereto (X1X2 direction) are separated and seamlessly continuously arranged. Therefore, the interference magnetic field in the sensitivity direction and the direction orthogonal thereto can be reduced, thereby increasing Hk on the surface of the inner shield 124a.

[0079] Figure 5 (a) Figure 5 (b) and Figure 5 (c) Figure 3 1 and 1 are schematic diagrams of the PP cross section, the Q1Q1 cross section, and the R1R1 cross section of the magnetic sensor 12. These diagrams schematically show the stacked structure of the magnetic sensor 12 of the magnetic balance type.

[0080] Figure 5 (a) shows a cross section including the first coil portion 121a, the second coil portion 121b, the magnetoresistance effect element 122a, and the inner shield 124a. Figure 5 (b) and Figure 5(c) shows a cross section including the first coil portion 121a and the outer shield 124b. In addition, in these figures, in order to show the entire stacked structure, the structure is simplified and part of the structure is omitted.

[0081] like Figure 5 As shown in (a), a magnetoresistance effect element 122a is provided on an insulating film 22 formed on a substrate 21 composed of silicon. Above the magnetoresistance effect element 122a (in the Z1 direction), a first coil portion 121a and a second coil portion 121b (appropriately referred to as feedback coil 121) are provided via a polyimide film and a silicon oxide film (not shown). The feedback coil 121 can be formed by patterning using photolithography and etching after forming a film containing a conductive material such as a metal, for example.

[0082] The inner shield 124a is formed in a region overlapping with the magnetoresistance effect element 122a when viewed from above in the Z2 direction, via a polyimide film (not shown) formed to cover the feedback coil 121. The inner shield 124a can be formed using a high magnetic permeability material such as an amorphous magnetic material, a Permalloy-based magnetic material, or an iron-based microcrystalline material. A silicon oxide film (not shown) is formed on the inner shield 124a.

[0083] exist Figure 5 (a) and Figure 5 In (b), the induced magnetic field A from the conductor 11 is indicated by a solid arrow, and the canceling magnetic field B from the first coil portion 121a is indicated by a dotted arrow.

[0084] like Figure 5 As shown in (a), in the inner shield 124a, the direction of the induced magnetic field A is the same as the direction of the canceling magnetic field B of the feedback coil 121. Therefore, in the magnetic sensor 12, the inner shield 124a has a function of enhancing the canceling magnetic field B of the feedback coil 121 in addition to the magnetic attenuation function. Since the inner shield 124a functions as a magnetic yoke, it is possible to reduce the current flowing in the feedback coil 121, thereby saving power.

[0085] like Figure 5 As shown in (b), in the outer shield 124b, the direction of the induced magnetic field A is opposite to the direction of the canceling magnetic field B of the first coil part 121a. In this way, in the outer shield 124b, the canceling magnetic field B cancels the induced magnetic field A, so it is difficult for the outer shield 124b to be magnetically saturated. Therefore, the saturation magnetic field of the outer shield 124b can be increased, thereby effectively shielding and reducing the magnetic field in the sensing direction (Y1Y2 direction). As a result, the anisotropic magnetic field (Hk) on the surface of the inner shield 124a can be increased and the measurable range of the magnetic sensor 12 can be expanded.

[0086] Figure 5 (b) shows the Q1Q1 section, but in the Q2Q2 section, the relationship between the induced magnetic field A and the offset magnetic field B is Figure 5 (b) is the same as that of the induced magnetic field A, and the direction of the induced magnetic field A is the same as that of the second coil portion 121b (refer to Figure 3 Therefore, regardless of the direction (Y1 direction or Y2 direction) of the magnetic field in the sensing direction (Y1Y2 direction), the magnetic field applied to the inner shield 124a can be reduced by the outer shield 124b in the same manner.

[0087] like Figure 5 As shown in (c), at a portion of the outer shield 124b located in a direction (X1X2 direction) perpendicular to the sensing direction with respect to the inner shield 124a, the induced magnetic field A is perpendicular to the canceling magnetic field B of the first coil portion 121a. Figure 5 (c) shows the R1R1 cross section, and in the R2R2 cross section, the induced magnetic field A is also orthogonal to the canceling magnetic field B of the second coil portion 121b. Therefore, regardless of the direction of the magnetic field in the direction orthogonal to the sensing direction (X1X2 direction), the interference magnetic field applied to the inner shield 124a can be reduced by the outer shield 124b. In addition, in the R2R2 cross section, the direction of the canceling magnetic field B is Figure 5 The opposite is true in (c).

[0088] Figure 6 (a) is a schematic diagram showing the magnetic field around the outer shield 124b formed in an annular shape. Figure 6 (b) is a schematic diagram showing the arrangement of the magnetic field detection unit 122 , the feedback coil 121 , and the shield 124 of the magnetic sensor 12 .

[0089] like Figure 6 As shown in FIG. 1 , by forming the outer shield 124b into a ring shape, the orthogonal magnetic field orthogonal to the detection direction reaching the magnetic field detection unit 122 can be attenuated and reduced. In addition, the magnetic field from the outside reaching the inner shield 124a located inside the outer shield 124b can be attenuated and reduced. As a result, the anisotropic magnetic field (Hk) on the surface of the inner shield 124a can be increased.

[0090] In addition, if Figure 6As shown in (b), the four magnetoresistive effect elements 122a to 122d constituting the full bridge circuit in the magnetic field detection unit 122 overlap with the imaginary center line CL when viewed from the normal direction of the inner shield 124a, and are arranged in a straight line along the imaginary center line CL. The feedback coil 121 and the shield 124 are respectively arranged in line symmetry with respect to the imaginary center line CL. Therefore, in the Y1 direction and the Y2 direction in the sensitivity direction for sensing the induced magnetic field A, the positional relationship between the feedback coil 121 and the shield 124 and the magnetic field detection unit 122 is the same. Therefore, the induced magnetic field A can be sensed with the same accuracy regardless of whether the direction of the magnetic field is the Y1 direction or the Y2 direction. That is, the current I can be sensed with high accuracy regardless of the direction of the current flowing in the conductor 11.

[0091] Figure 7 (a) is a graph schematically showing the relationship between the width (W1) of the inner shield 124a and the anisotropic magnetic field (Hk). Figure 7 (b) is a graph schematically showing the relationship between the thickness of the inner shield 124a and the anisotropic magnetic field (Hk).

[0092] Enlarged magnetic sensor 12 (refer to Figure 3 ) requires increasing the anisotropic magnetic field (Hk) of the inner shield 124a. Figure 7 As shown in (a), it is effective to increase the aspect ratio (aspect) of the shape (rectangle) of the inner shield 124a viewed from the normal direction, or Figure 7 As shown in (b), the shield film thickness of the inner shield 124a is increased.

[0093] However, when the aspect ratio of the inner shield 124a is increased, the inner shield 124a is not as good as the inner shield 124a. Figure 3 , Figure 6 ) is particularly limited in the short dimension direction (width direction, sensitivity direction, Y1Y2 direction) in order to balance the position of the induced magnetic field. In addition, if the aspect ratio is increased, the magnetic permeability (μ) of the inner shield 124a will decrease as a contradictory or incompatible property, and there is a problem that the effect of shielding the induced magnetic field A is weakened.

[0094] In addition, if the film thickness of the inner shield 124a is increased, the manufacturing becomes very difficult. As problems that are likely to occur when the film thickness is increased, for example, it is difficult to evenly apply a thick resist to the inside of a wafer, and cracks and film peeling are likely to occur due to increased stress in the shield 124.

[0095] Therefore, in the magnetic sensor 12 of the present embodiment, the outer shield 124b is arranged on the same plane as the inner shield 124a in such a manner as to surround the inner shield 124a along the outer periphery of the feedback coil 121 when viewed from the normal direction (Z1 direction) of the inner shield 124a, thereby achieving a high shielding effect against the induced magnetic field A without increasing the film thickness of the shield 124.

[0096] [Variation]

[0097] Figure 8 For Figure 3 FIG. 1 is a top view for explaining the structure of a magnetic sensor 52 of a magnetic balance type according to a modified example of the embodiment shown in FIG. Figure 1 ) is provided with an annular outer shield 124b of the inner shield 124a, and is provided with outer shields 124c and 124d surrounding the inner shield 124a on both sides in the magnetic field detection direction of the magnetic sensor 52. This point is different from the magnetic sensor 12, and the other structures are the same.

[0098] The outer shields 124c and 124d are arranged outside the inner shield 124a in the magnetic field detection direction (Y1Y2 direction) of the magnetoresistive effect elements 122a to 122d. That is, the outer shields 124c and 124d are arranged outside the inner shield 124a in the directions of the induction magnetic field A and the cancellation magnetic field B.

[0099] The outer shields 124c and 124d are arranged outside the magnetic field detection direction of the magnetoresistive effect elements 122a to 122d so as to overlap the feedback coil 121, so that the outer shield 124b is also difficult to be magnetically saturated. Therefore, the outer shields 124c and 124d can reduce the magnetic field from the outside to the inner shield 124a, increase the anisotropic magnetic field (Hk) on the surface of the inner shield 124a, and expand the measurable range of the magnetic sensor 52.

[0100] (Second embodiment)

[0101] Fig.12 (a) Fig.12 (b) and Fig.12 (c) is a plan view of the magnetic field detection unit 122 , the feedback coil 121 , and the shield 124 of the magnetic sensor 13 according to the present embodiment.

[0102] Fig.13 1 is a plan view for explaining the structure of the magnetic sensor 13 according to the embodiment. Fig.13 Schematically shows Fig.12 (a)~ Fig.12(c) shows the positional relationship of the components in a stacked state.

[0103] like Fig.12 (a)~ Fig.12 (c) and Fig.13 As shown, the magnetic sensor 13 of this embodiment has the same structure as the magnetic sensor 12 of the first embodiment except that the shield 124 is composed of an annular outer shield 124b. Therefore, in this embodiment, the description of the structure common to the magnetic sensor 12 is omitted, and the different structures are described.

[0104] The shield 124 (outer shield 124b) improves the perpendicular magnetic field resistance of the magnetic sensor 13 by shielding the magnetic field in the perpendicular direction of sensitivity. First, the shift in the resistance of the magnetic field detection unit 122 when the perpendicular magnetic field is applied to the magnetic sensor 13 will be described below.

[0105] Fig.19 The cross-sectional view schematically shows the stacked structure of the magnetoresistive effect element 122a~d composed of GMR elements. The magnetoresistive effect element 122a~d has a stacked structure of a fixed magnetic layer 111, a non-magnetic material layer 112, and a free magnetic layer 113. Its resistance value changes according to the relative relationship between the magnetization direction of the fixed magnetic layer 111 whose magnetization direction is fixed and the magnetization direction of the free magnetic layer 113 whose magnetization direction changes according to the external magnetic field. Magnetic sensor 13 (refer to Fig.13 ) can sense the direction and strength of the external magnetic field based on the change in the resistance value.

[0106] If the internal magnetic wall of the free magnetic layer 113 moves, Barkhausen noise will be generated. Therefore, as a bias magnetic field for stabilizing the output of the magnetic sensor 13 having the GMR element 110, an exchange bias magnetic field using an exchange coupling magnetic field with the antiferromagnetic layer 114 is applied in a direction orthogonal to the sensitivity axis. By applying the bias magnetic field, the magnetization direction of the soft magnetic material forming the free magnetic layer 113 can be made consistent. In addition, the bias magnetic field is not limited to the exchange bias magnetic field, and can also be a hard magnetic bias magnetic field using a permanent magnet.

[0107] When a weak external magnetic field in which the magnetization direction is not reversed is applied, the free magnetic layer 113 returns to the initial state before the external magnetic field is applied by returning to the zero magnetic field. However, when a strong external magnetic field in which the magnetization direction is reversed is applied, the free magnetic layer 113 does not return to the initial state even if it returns to the zero magnetic field. That is, if the magnetization direction of the free magnetic layer 113 is reversed due to a strong external magnetic field, even if it returns to the zero magnetic field in addition to the external magnetic field, a deviation (offset) from the initial state occurs due to the hysteresis of the free magnetic layer 113.

[0108] Fig. 20 1 is an explanatory diagram for explaining the shift in resistance due to the hysteresis of the free magnetic layer 113 of the magnetoresistance effect elements 122a to 122d. Fig. 20 As shown in FIG. 1 , when the external magnetic field (orthogonal magnetic field) applied to the free magnetic layer 113 in a direction orthogonal to the sensitivity axis is smaller than the reversal magnetic field (Q), if the external magnetic field returns to zero, the free magnetic layer 113 changes along the solid line in the direction of arrow (1) and returns to the initial state. Therefore, when the magnitude of the external magnetic field changes from 0 to less than the reversal magnetic field, if the external magnetic field becomes zero, the resistance of the free magnetic layer 113 becomes the initial value (P).

[0109] However, when an external magnetic field greater than the reversal magnetic field is applied, the free magnetic layer 113 will not return to its initial state even if the external magnetic field returns to zero. For example, when a saturation magnetic field (R) is applied to the free magnetic layer 113, the resistance changes as shown by the dotted line due to the hysteresis of the free magnetic layer 113. Therefore, if the external magnetic field becomes zero, the resistance of the free magnetic layer 113 changes in the direction of the arrow (2) along the dotted line, and becomes (S). In this way, when the magnitude of the external magnetic field is greater than the reversal magnetic field, the resistance of the free magnetic layer 113 deviates from the initial value due to the hysteresis of the free magnetic layer 113.

[0110] As described above, when an external magnetic field larger than the reversal magnetic field is applied and the free magnetic layer 113 is reversed from its initial magnetization direction, the resistance of the free magnetic layer 113 shifts after the magnetic field becomes zero. The shift in resistance generated in the free magnetic layer 113 varies depending on the magnitude of the external magnetic field. Fig. 20 If the resistance of the free magnetic layer 113 changes, the sensing accuracy decreases, so it is preferable that the magnetic sensor 13 has a high resistance to an external magnetic field orthogonal to the sensitivity axis.

[0111] In order to attenuate the external magnetic field and improve the sensing accuracy, the magnetic sensor 13 includes a shield 124. The external magnetic field is applied to the magnetic field detection unit 122 while being attenuated by the shield 124. Therefore, the reverse magnetic field is biased toward the high magnetic field side, and the range in which the sensing accuracy of the magnetic sensor can be well maintained is widened.

[0112] like Fig.13As shown in FIG. 1 , the shielding member 124 is configured to overlap the feedback coil 121 along the outer periphery of the feedback coil 121 when viewed from the normal direction thereof, that is, when viewed from the Z1 direction toward the Z2 direction. The shielding member 124 preferably completely covers the outer periphery of the feedback coil 121, but may cover a portion instead of the entire outer periphery. In addition, the shielding member 124 may cover a portion of the outer periphery of the feedback coil 121 when viewed from the normal direction thereof, and a portion may extend from the feedback coil 121.

[0113] Fig.14 (a) Fig.14 (b) and Fig.14 (c) Fig.13 Schematic diagram of the PP section, the Q1Q1 section and the R1R1 section of the magnetic sensor 13. These figures schematically show the stacked structure of the magnetic sensor 12 of the magnetic balance type, with the induced magnetic field A from the conductor 11 indicated by the solid arrow and the canceling magnetic field B from the first coil portion 121a indicated by the dotted arrow.

[0114] like Fig.14 As shown in (a), the magnetic sensor 13 does not include the inner shield 124a between the conductor 11 and the feedback coil 121 (see Figure 2 (c) Figure 3 The inner shield 124a is necessary when detecting a wide magnetic field range, but is not necessary when detecting a relatively small magnetic field range.

[0115] For example, if the inner shield 124a is provided when the magnetic field detection unit 122 is a GMR element, the magnetic field detection unit 122 is easily affected by the hysteresis of the inner shield 124a. Therefore, if the desired detection range can be ensured, it is preferable not to have the inner shield 124a like the magnetic sensor 13. Therefore, a balanced magnetic sensor (current sensor) for weak magnetic field detection is sometimes composed only of a full bridge circuit composed of GMR elements and a feedback coil.

[0116] However, the magnetic sensor composed only of a full-bridge circuit and a balanced coil is susceptible to interference magnetic fields. The magnetic sensor element (chip) alone does not have the function of attenuating interference magnetic fields, and a shielding member may be provided in the package or module. However, in this case, the structure tends to become complicated, and there is a problem that it is difficult to miniaturize due to the increased size.

[0117] On the other hand, the shield 124 also has the effect of attenuating the interference magnetic field as a component other than the detection magnetic field. Therefore, the magnetic sensor 13 has an outer shield 124b as a shield 124 that mitigates the influence of the interference magnetic field. The magnetic sensor 13 is provided with a shield for attenuating the interference magnetic field in its chip, which is beneficial for miniaturization. In addition, the outer shield 124b is not provided directly above the magnetic field detection unit 122 constituting the full bridge circuit, but is provided to surround it at a slightly deviated position. Therefore, the influence of the hysteresis of the shield 124 on the magnetic sensor 13 can be reduced.

[0118] Fig.15 (a) is a schematic diagram showing the magnetic field around the outer shield 124b formed in an annular shape. Fig.15 (b) is a schematic diagram showing the arrangement of the magnetic field detection unit 122 , the feedback coil 121 , and the shield 124 of the magnetic sensor 13 .

[0119] like Fig.15 As shown in (a), by forming the outer shield 124b into a ring shape, the area inside it is less likely to be affected by the surrounding magnetic field. That is, by arranging the magnetic field detection unit 122 inside the outer shield 124b formed into a ring shape, the magnetic field from the outside that reaches the magnetic field detection unit 122 can be attenuated and reduced. As a result, the resistance of the magnetic sensor 13 to the external magnetic field is improved.

[0120] In addition, if Fig.15 As shown in FIG. 1( b ), the magnetic field detection unit 122 and the feedback coil 121 are arranged to be line symmetrical with respect to the imaginary center line CL, and a shield 124 composed of an annular outer shield 124 b is provided on the feedback coil 121 (on the Z2 side of the Z1Z2 axis) to surround the magnetic field detection unit 122 and the feedback coil 121. Therefore, the induced magnetic field A and the current I can be sensed with high accuracy regardless of the direction of the current flowing in the conductor 11.

[0121] [Example]

[0122] <Examples 1 and 2, Comparative Example 1>

[0123] As Example 1, a magnetic sensor 12 having the configuration of the embodiment is used (see Figure 3 ), as Example 2, a magnetic sensor 52 having a modified structure is used (refer to Figure 8 ), the magnetic force is measured to evaluate the linearity.

[0124] Fig. 9 This is a top view for explaining the structure of the magnetic sensor of Comparative Example 1. Fig. 9As Comparative Example 1, a current sensor in which one coil portion and one shield were overlapped with a magnetic field detection bridge circuit having four magnetoresistive effect elements was used to measure magnetic force and evaluate linearity.

[0125] The common conditions in the current sensors of Examples 1 and 2 and Comparative Example 1 are as follows.

[0126] Shield material: NiFe alloy (19.5 wt% Fe)

[0127] Dimensions of the inner shield (Example) and shield (Comparative Example) directly above the magnetic field detection unit: 800 μm × 150 μm

[0128] Film thickness of inner shield (Examples 1 and 2) and shield (Comparative Example 1): 17 μm

[0129] Distance between magnetic field detection unit and shield (Z1Z2 direction): 10μm

[0130] Number of turns of the feedback coil in the area above the magnetic field detection unit, i.e., overlapping the magnetic field detection unit: 24

[0131] Fig.10 This is a diagram schematically showing the calculation method of the output linearity of the magnetic sensor. Linearity is defined by the ratio (% / FS) of the difference (maximum value) between the output measured value and the approximate straight line to the full scale. According to this definition, the smaller the linearity (% / FS) value is, the closer it is to the ideal straight line, indicating that it is a magnetic sensor with high accuracy.

[0132] Fig.10 In the graph of , the horizontal axis represents the magnetic field, and the vertical axis represents the feedback current. Fig.10 As shown by the solid line in the middle, the actual measured value of the feedback current is different due to hysteresis in the case of increasing magnetic field and decreasing magnetic field. Therefore, based on the measured value, the approximate straight line is obtained by least square approximation, and the difference between the measured value and the value of the approximate curve is obtained, that is, the maximum value of the absolute value of the value obtained by subtracting the value obtained by the approximate curve under the same magnetic field as the measured value from the measured value, and the ratio of the maximum value to the full scale is calculated to set the linearity of the magnetic sensor. In addition, the full scale (FS) refers to the difference between the feedback current of the minimum magnetic field and the maximum magnetic field within the range of the magnetic field where the linearity is calculated.

[0133] The results of evaluating the linearity of the magnetic sensors of the examples and comparative examples are shown in FIG. Fig.11 Figures and Table 1.

[0134] [Table 1]

[0135]

[0136] The results of evaluating the linearity of the magnetic sensors of Examples 1 and 2 and Comparative Example 1 show that the induced magnetic field A can be detected with high accuracy by forming a shield arranged to overlap the feedback coil with an inner shield and an outer shield, wherein the inner shield is arranged to weaken the intensity of the magnetic field to be measured applied to the magnetic field detection unit, and the outer shield is arranged to weaken the intensity of the magnetic field to be measured applied to the inner shield. In addition, from the viewpoint of improving the linearity, it is more preferable to form an outer shield in a seamless annular shape than to surround the inner shield on both sides of the magnetic field detection direction.

[0137] <Example 3, Comparative Example 2>

[0138] The common conditions in the current sensors of Example 3 and Comparative Example 2 are as follows.

[0139] Number of turns of the feedback coil in the area above the magnetic field detection unit, i.e., overlapping the magnetic field detection unit: 24

[0140] Film structure of a GMR element used as a magnetoresistive element. The numbers in parentheses indicate the thickness of the layer.

[0141] Base layer: NiFeCr(42) / Fixed magnetic layer: Fe 60at％ Co 40at％ (19) / Non-magnetic material layer: Ru(3.6) / Fixed magnetic layer: Co 90at％ Fe 10at％ (24) / non-magnetic material layer: Cu(20) / free magnetic layer: [Co 90at％ Fe 10at％ (10) / Ni 82.5at％ Fe 17.5at％ (70)] / Antiferromagnetic layer: IrMn(80) / Protective layer: Ta(100)

[0142] (Example 3)

[0143] use Fig.13 The magnetic sensor shown includes a shield 124 formed of an outer shield 124b.

[0144] Shield material: NiFe alloy (19.5 wt% Fe)

[0145] Shield shape: 1000μm×1500μm, width 220μm

[0146] Shielding film thickness: 17μm

[0147] Distance between magnetic field detection unit and shield (Z1Z2 direction): 10μm

[0148] (Comparative Example 2)

[0149] In the configuration without the shield 124, a magnetic sensor 13 different from that of the third embodiment is used. Fig.16 The magnetic sensor 53 is shown.

[0150] (Measurement of offset variation)

[0151] For each of the magnetic sensors of Example 3 and Comparative Example 2, the external magnetic field (stress magnetic field, orthogonal magnetic field) applied in a direction orthogonal to the sensitivity axis is set to ±XmT (X is 5 to 22, each 1 mT), and the external magnetic field is changed in a manner such that the absolute value of the alternatingly applied positive external magnetic field and negative external magnetic field gradually increases, while the offset change in the output of the magnetic sensor is measured.

[0152] Fig.17 This is a graph showing the results of measuring the external magnetic field resistance of the magnetic sensors of Example 3 (10 each).

[0153] Fig.18 : This is a graph showing the measurement results of the external magnetic field resistance of the magnetic sensors of Comparative Example 2 (10 sensors each).

[0154] like Fig.17 As shown, the offset of the magnetic sensor of Example 3 occurs up to an external magnetic field of ±15 mT, and the amount of offset variation is suppressed to be small.

[0155] In contrast, Fig.18 As shown, in the magnetic sensor of Comparative Example 2, the external magnetic field produces an offset of ±10 mT, and the offset fluctuation amount is also large.

[0156] according to Fig.17 as well as Fig.18 The results shown show that the orthogonal magnetic field resistance of the magnetic sensor is improved by providing an annular shield disposed in an overlapping manner at a position where the direction of the induced magnetic field is opposite to the direction of the canceling magnetic field B from the feedback coil. In particular, by combining with a feedback coil for magnetic balance in an 8-shaped configuration having a first coil and a second coil disposed in a linearly symmetrical manner when viewed in the thickness direction, a magnetic sensor having excellent orthogonal magnetic field resistance can be realized.

[0157] Industrial Applicability

[0158] The present invention can be used as a sensor for sensing the magnitude of a current for driving a motor, for example.

[0159] Description of Reference Numerals

[0160] 11: Conductor

[0161] 12, 13, 52, 53: Magnetic sensor (current sensor)

[0162] 21: Substrate

[0163] 22: Insulation film

[0164] 31, 31a, 31b, 31c, 31d, 31e, 31f, 31g: long stripe pattern

[0165] 32a, 32b: Connection terminals

[0166] 33a, 33b, 33c, 33d, 33e, 33f: connection part

[0167] 111: Fixed magnetic layer

[0168] 112: Non-magnetic material layer

[0169] 113: Free magnetic layer

[0170] 114: Antiferromagnetic layer

[0171] 121: Feedback coil

[0172] 121a: First coil portion

[0173] 121b: Second coil portion

[0174] 122: Magnetic field detection unit

[0175] 122a, 122b, 122c, 122d: magnetoresistance effect elements

[0176] 123: Amplifier

[0177] 124: Shielding

[0178] 124a: Inner shield

[0179] 124b, 124c, 124d: Outer shielding member

[0180] A: Induced magnetic field (magnetic field to be measured)

[0181] B: Offset magnetic field

[0182] I: Current

[0183] Out1: first output voltage

[0184] Out2: Second output voltage

[0185] Vdd: power supply voltage

[0186] GND: Ground voltage

[0187] CL: Imaginary center line

Claims

1. A magnetic sensor comprising a magnetic field detection unit composed of a magnetoresistive element, a feedback coil and a shield, wherein: The feedback coil is arranged to overlap with the magnetic field detection unit. The shielding member is arranged to overlap with the feedback coil. The shielding member has: an inner shield configured to weaken the intensity of the magnetic field to be measured applied to the magnetic field detection unit; and an outer shield configured to weaken the intensity of the magnetic field to be measured applied to the inner shield, The feedback coil includes a first coil portion and a second coil portion. The first coil portion and the second coil portion are arranged so that their shapes when viewed from the normal direction of the inner shield are line-symmetrical with respect to an imaginary center line orthogonal to the sensitivity direction of the magnetoresistive effect element. The magnetic field detection unit is a full-bridge circuit configured with four magnetoresistive effect elements. The four magnetoresistive effect elements are provided so as to overlap with the imaginary center line when viewed in the normal direction of the inner shield.

2. The magnetic sensor according to claim 1, wherein: In the inner shield, the direction of the magnetic field to be measured is the same as the direction of the canceling magnetic field of the feedback coil. The outer shield has a portion in which a direction of the magnetic field to be measured is opposite to a direction of the canceling magnetic field of the feedback coil.

3. The magnetic sensor according to claim 1, wherein: The outer shield is formed to surround the inner shield.

4. The magnetic sensor according to claim 1, wherein: The outer shield is formed in a ring shape.

5. The magnetic sensor according to claim 1, wherein: The shape of the inner shield as viewed from the normal direction thereof is a quadrangle or a rounded quadrangle with rounded corners.

6. The magnetic sensor according to claim 1, wherein: The width of the outer shield is less than or equal to the width of the inner shield.

7. A current sensor, characterized in that: A magnetic sensor according to claim 1 is provided.

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