JP6970591B2 - Magnetic sensor and current sensor - Google Patents

Description

The present invention relates to a magnetic sensor and a current sensor including the magnetic sensor.

In fields such as motor drive technology for electric vehicles and hybrid cars, and in infrastructure-related fields such as pole transformers, relatively large currents are handled, so there is a need for current sensors that can measure large currents in a non-contact manner. There is. As such a current sensor, one using a magnetic sensor that detects an induced magnetic field from a measured current is known. Examples of the magnetic detection element for a magnetic sensor include a magnetoresistive element such as a GMR (giant magnetoresistive effect) element.

Although the magnetoresistive sensor has high detection sensitivity, it is characterized by high linearity and a relatively narrow range of detectable magnetic field strength. Therefore, as in the current sensor shown in FIG. 3 of Patent Document 1, a magnetic shield is arranged between the measured current and the magnetoresistive sensor, and an induced magnetic field substantially applied to the magnetoresistive sensor. In some cases, a method of reducing the strength of the magnetic field to be measured so that the magnitude of the measured magnetic field is within the magnetic field strength range having good detection characteristics is used.

By using the magnetic shield in this way, it is possible to substantially reduce the strength of the magnetic field applied to the magnetoresistive sensor and expand the measurement range of the magnetic field strength, but the magnetic shield is magnetic. It may cause hysteresis. In Patent Document 2, it is realized that by providing a hard bias layer on the magnetic shield, this temporal hysteresis is suppressed and the linearity of the output of the magnetoresistive sensor is improved.

International Publication No. 2011/111493 International Publication No. 2011/155261

When the magnetic field applied to the magnetic shield is as strong as about several tens of mT, residual magnetization is likely to occur in the magnetic shield even if the magnetic shield is made of a soft magnetic material. When a magnetic field based on the residual magnetization of the magnetic shield generated in this way is applied to the magnetoresistive sensor, the zero magnetic field hysteresis of the magnetoresistive sensor increases to the negative side, which adversely affects the measurement accuracy of the magnetoresistive sensor. There is a risk that it will end up.

In view of the present situation, the present invention is a magnetic sensor including a magnetic shield and a magnetoresistive sensor, and the measurement accuracy of the magnetoresistive sensor is unlikely to decrease even when the magnetic field applied to the magnetic sensor is large. It is intended to provide a magnetic sensor. It is also an object of the present invention to provide a current sensor including such a magnetic sensor.

The present invention provided to solve the above-mentioned problems is, in one embodiment, a magnetoresistive effect element having a sensitivity axis in a first direction and a magnetoresistive effect element arranged above the magnetoresistive effect element. A magnetic sensor including a magnetic shield that attenuates the strength of a magnetic field to be measured applied to an element, wherein the magnetic shield has a main body portion and a protruding portion protruding in the first direction. The main body portion has a shape having a length in a second direction orthogonal to the first direction in a plan view, and the protruding portion has a portion thinner than the main body portion. It is a sensor. With such a configuration, since the magnetic field based on the residual magnetization of the magnetic shield is emitted from the tip of the protrusion, it is applied in the direction opposite to the direction emitted from the magnetic shield and emitted to the magnetoresistive sensor. The strength of the magnetic field (recirculation magnetic field) to be generated can be reduced, and the hysteresis of the magnetoresistive sensor can be reduced.

It is preferable that the protruding portion is located at the lower end of the magnetic shield from the viewpoint of efficiently reducing the hysteresis of the magnetoresistive sensor.

In a plan view, it is preferable that the entire magnetoresistive sensor overlaps with the main body of the magnetic shield from the viewpoint of efficiently reducing the hysteresis of the magnetoresistive sensor.

The magnetic sensor may further include a magnetic equilibrium coil and measure the strength of the magnetic field to be measured based on the current flowing through the magnetic equilibrium coil. In this case, the magnetic equilibrium coil is a spiral coil, and it may be preferable that the coil is located between the magnetoresistive sensor and the magnetic shield.

As another aspect of the present invention, the magnetic sensor is provided, and the magnetic sensor provides a current sensor in which the induced magnetic field of the measured current is the measured magnetic field.

According to the present invention, even when the applied magnetic field is large and residual magnetization occurs in the magnetic shield, the influence of the recirculation magnetic field based on the residual magnetization on the magnetoresistive element is reduced. Therefore, a magnetic sensor is provided in which the measurement accuracy of the magnetoresistive effect element is unlikely to decrease. Further, a current sensor using such a magnetic sensor is also provided.

It is a top view which conceptually shows the structure of the magnetic sensor which concerns on one Embodiment of this invention. It is sectional drawing by V1-V1 line of FIG. It is a top view which conceptually shows the structure of the magnetic sensor which concerns on another Embodiment of this invention. FIG. 3 is a cross-sectional view taken along the line V2-V2 of FIG. It is a graph which shows the relationship between the distance D1 between a magnetic shield and a GMR element, and zero magnetic field hysteresis ZH.

FIG. 1 is a plan view conceptually showing the structure of a magnetic sensor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line V1-V1 of FIG.

As shown in FIGS. 1 and 2, the magnetic sensor 1 according to an embodiment of the present invention includes four magnetoresistive elements (magnetoresistive elements 11 to 14) and a magnetic shield 15.

Each of the four magnetoresistive elements of the magnetic sensor 1 according to the embodiment of the present invention has a meander shape (a shape formed by connecting a plurality of long patterns extending in the X1-X2 direction so as to be folded back). It is equipped with a giant magnetoresistive effect element (GMR element). The sensitivity axial direction P of each magnetoresistive effect element (magnetic resistance effect element 11 to 14) is represented by an arrow in FIG. 1, and the sensitivity axial direction P of the magnetoresistive effect element 11 and the magnetoresistive element 14 ( The first direction) is set to face the Y2 side in the Y1-Y2 direction, and the sensitivity axial direction P of the magnetoresistive effect element 12 and the magnetoresistive sensor 13 is set to face the Y1 side in the Y1-Y2 direction.

The wiring 5 connected to the input terminal 5a is connected to one end of the magnetoresistive element 11, and the other end of the magnetoresistive element 11 and one end of the magnetoresistive element 12 are connected in series to form the magnetoresistive element 12. The other end of the is connected to the ground terminal 6a via the wiring 6. The wiring 5 connected to the input terminal 5a branches in the middle and is also connected to one end of the magnetoresistive sensor 13, and the other end of the magnetoresistive element 13 and one end of the magnetoresistive element 14 are connected in series. The other end of the magnetoresistive sensor 14 is connected to the ground terminal 6a via the wiring 6. The first midpoint potential measuring terminal 7a is connected by a wiring 7 between the other end of the magnetoresistive effect element 11 and one end of the magnetoresistive effect element 12, and the second midpoint potential measuring terminal 8a is a magnetic resistance. It is connected by a wiring 8 between the other end of the effect element 13 and one end of the magnetoresistive effect element 14. By comparing the potential of the first midpoint potential measuring terminal 7a with the potential of the second midpoint potential measuring terminal 8a, the induced magnetic field (measured magnetic field) of the measured current Io flowing through the current line 40 The strength and orientation can be measured.

FIG. 2 is obtained by cutting the magnetic sensor 1 at a plane whose normal is the direction along the long axis direction (X1-X2 direction) of a plurality of long patterns constituting the meander shape of the magnetoresistive effect element 11. It is a cross-sectional view. The Y1-Y2 direction (first direction), which is one of the inward directions in the cross section, is the sensitivity axial direction P (direction toward Y2 in the Y1-Y2 direction) of the magnetoresistive effect element 11. The magnetoresistive element 11 is formed on the substrate 29 and is covered with an insulating layer IM made of an insulating material (alumina, silicon nitride or the like is a specific example).

The magnetic shield 15 is arranged on the magnetoresistive effect element 11 (Z1 side in the Z1-Z2 direction) at a distance from the magnetoresistive sensor 11. The separation distance between the magnetic shield 15 and the magnetoresistive sensor 11 is adjusted by the thickness of the insulating layer IM located between them.

In the magnetic sensor 1 according to the embodiment of the present invention, the magnetic shield 15 attenuates the strength of the measured magnetic field applied to the magnetoresistive effect element (magnetoresistive element 11 to 14). As shown in FIG. 1, it has a rectangular shape having a second direction (X1-X2 direction) orthogonal to the first direction (Y1-Y2 direction) in a plan view (viewed from the Z1-Z2 direction). It has a main body portion 150 and a protruding portion 15P protruding from the main body portion 150 in at least a first direction (Y1-Y2 direction). As shown in FIG. 2, the protruding portion 15P has a portion thinner than the main body portion 150, and is located at the lower end of the magnetic shield 15 (the end portion on the Z2 side in the Z1-Z2 direction).

Specifically, such a structure is located at the lower end of the magnetic shield (Z1-Z2 direction Z2 side end) and is formed on the base layer 151 made of a soft magnetic material and above the base layer 151 (Z1-Z2 direction Z1). It is realized by a structure having a soft magnetic layer 152 formed on the side). The portion of the base layer 151 on which the soft magnetic layer 152 is not formed on the upper side (Z1 side in the Z1-Z2 direction) is the protruding portion 15P, and the protruding portion 15P is the magnetoresistive effect element 11 when viewed from the Z1-Z2 direction. It is located in a state of protruding outward in the Y1-Y2 direction. In the magnetic sensor 1, as shown in FIG. 2, the protrusions 15P are provided on both sides of the magnetic shield 15 in the Y1-Y2 direction.

Since the main body 150 has a second direction (X1-X2 direction) as a longitudinal direction, it is difficult to magnetize in the first direction (Y1-Y2 direction), which is short, due to the shape magnetic anisotropy effect, but it is external. When the magnetic field is strong, residual magnetization M0 may occur in the first direction (Y1-Y2 direction) as shown in FIG. Even in such a case, by providing the protruding portion 15P in this way, the magnetic field based on the residual magnetization M0 of the magnetic shield 15 is mainly emitted from the tip PE of the protruding portion 15P to the outside of the magnetic shield 15. NS. As a result, the strength of the magnetic field (refluxing magnetic field RM0) applied to the magnetoresistive sensor 11 in the direction opposite to the direction of the residual magnetization M0, which is the magnetic field based on the residual magnetization M0 of the magnetic shield 15, becomes relatively low. Therefore, the zero magnetic field hysteresis ZH of the magnetoresistive effect element 11 becomes small. Therefore, the measurement accuracy of the magnetic sensor 1 provided with the magnetoresistive effect element 11 is improved as compared with the case where the magnetic shield 15 does not have the protruding portion 15P.

As shown in FIG. 2, the protruding portion 15P is preferably located at the lower end (Z2 side end portion in the Z1-Z2 direction) of the magnetic shield 15. When such a configuration is provided, when the magnetic field based on the residual magnetization M0 of the magnetic shield 15 is emitted from the Y1 side in the Y1-Y2 direction of the magnetic shield 15, all the components circulating in the Y1 side in the Y1-Y2 direction are all. It is emitted from the tip 15PE of the protruding portion 15P located outside the end portion in the Y1-Y2 direction of the magnetoresistive effect element 11 when viewed from the Z1-Z2 direction. Therefore, the residual magnetization M0 emitted from the tip PE of the magnetic shield 15 is emitted from a position farther from the end of the magnetoresistive effect element 11 when the magnetic sensor 1 is viewed from the Z1-Z2 direction. The strength of application of the magnetic field (refluxing magnetic field RM0) based on the residual magnetization M0 of the shield 15 to the magnetoresistive sensor 11 can be made weaker.

In a plan view (viewed from the Z1-Z2 direction), it is preferable that the entire magnetoresistive element 11 overlaps the magnetic shield 15, and more preferably it overlaps the main body 150 of the magnetic shield 15. In this case, the distance between the tip 15PE of the protrusion 15P, which is the emission part of the magnetic field (recirculation magnetic field RM0) based on the residual magnetization M0 of the magnetic shield 15, and the X1-X2 direction (first direction) of the magnetoresistive element 11. The distance can be appropriately secured, and the strength of the recirculation magnetic field RM0 applied to the magnetoresistive effect element 11 can be stably reduced.

The base layer 151 and the soft magnetic layer 152 are made of a soft magnetic material containing iron group elements such as Fe, Co, and Ni. The thickness of the base layer 151 is arbitrarily set within a range in which the protrusion 15P functions as a magnetic field emitting portion based on the residual magnetization M0 of the magnetic shield 15. An example in which the thickness of the base layer 151 is not limited is 10 nm or more and 1 μm or less. The thickness of the base layer 151 may be preferably 20 nm or more and 500 nm or less, and more preferably 50 nm or more and 200 nm or less. The thickness of the soft magnetic layer 152 is arbitrarily set within a range in which the magnetic shield 15 has a predetermined magnetic shielding function. An example in which the thickness of the soft magnetic layer 152 is not limited is 1 μm or more and 50 μm or less, and the thickness of the soft magnetic layer 152 may be preferably 5 μm or more and 30 μm or less, and more preferably 10 μm or more and 25 μm or less. .. The thickness (Z1-Z2 direction length) of the base layer 151 constituting the projecting portion 15P is determined from the viewpoint of increasing the substantial aspect ratio of the magnetic shield 15 as described below, and from the projecting portion 15P to the magnetic shield 15. From the viewpoint that the magnetic field based on the residual magnetization M0 is efficiently emitted, the thickness is preferably 3% or less, more preferably 1% or less of the thickness of the soft magnetic layer 152.

When the thickness of the base layer 151 is sufficiently thinner than that of the soft magnetic layer 152 as described above, the portion of the magnetic shield 15 that generates the anisotropic magnetic field Hk is substantially only the main body portion 150. Therefore, the substantial aspect ratio of the magnetic shield 15 that affects the degree of the anisotropic magnetic field Hk is the lateral direction (Y1-Y2 direction) of the length in the longitudinal direction (X1-X2 direction) of the main body 150. It is the ratio to the length of. By increasing the substantial aspect ratio of the magnetic shield 15, the anisotropic magnetic field Hk of the magnetic shield 15 can be increased, and the linear region of the magnetization curve can be made larger in the sensitivity axis direction of the magnetic sensor 1 of the magnetic shield 15. .. As a result, the linear region of the output of the magnetic sensor 1 becomes large, and the dynamic range of the magnetic sensor 1 can be further expanded.

As described above, when the magnetic sensor 1 is viewed from the Z1-Z2 direction, it is preferable that the end portion of the magnetic shield 15 is far from the end portion of the magnetoresistive effect element 11. If the length in the −Y2 direction is extended, the substantial aspect ratio of the magnetic shield 15 is lowered, and the anisotropic magnetic field Hk of the magnetic shield is reduced. Therefore, as described above, by reducing the thickness of the protruding portion 15P extending from the main body portion 150 in the Y1-Y2 direction, the end portion of the magnetic shield 15 is not lowered in the substantial aspect ratio of the magnetic shield 15. (The tip 15PE of the protruding portion 15P) can be positioned far from the end portion of the magnetoresistive effect element 11. In this way, by reducing the thickness of the protruding portion 15P in the magnetic shield 15, the anisotropic magnetic field Hk of the magnetic shield 15 is increased, and the strength of the recirculation magnetic field RM0 applied to the magnetoresistive element 11 is increased. It is possible to achieve both reduction and reduction. As a result, even if a strong magnetic field is applied to the magnetic sensor 1 from the outside and a residual magnetic field is generated in the magnetic shield 15, the influence of the recirculation magnetic field generated by the residual magnetic field is reduced, and the hysteresis of the output of the magnetic sensor 1 is also reduced. At the same time, the dynamic range can be maintained large. As a result, it can be expected that the magnetic shield 15 is brought close to the magnetoresistive effect element 11 to increase the shielding effect of the magnetic field to be measured, and the dynamic range of the magnetic sensor 1 is further increased without increasing the hysteresis of the magnetic sensor 1. ..

In the magnetic shield 15 shown in FIG. 1, an oxidation protection layer PL made of tantalum (Ta) or the like is further formed on the soft magnetic layer 152 (Z1-Z2 direction Z1 side).

The method of manufacturing the magnetic shield 15 is arbitrary. As an example without limitation, the base layer 151 is formed by a dry process such as sputtering or a wet process such as electroplating, and a resist layer patterned in a predetermined shape is formed on the base layer 151 and then exposed. The soft magnetic layer 152 may be formed by electroplating with the stratum 151 as a conductive layer. In this case, when the base layer 151 is formed as the conductive layer, no special patterning is performed, and after the soft magnetic layer 152 is formed by electroplating, the base layer 151 is appropriately removed by etching or the like for efficiency. The magnetic shield 15 can be manufactured. In such a manufacturing method, the underlying layer 151 is not etched into the same shape as the soft magnetic layer 152 in a plan view (viewed from the Z1-Z2 direction), but is removed so as to have a protruding portion 15P. The magnetic shield 15 of the magnetic sensor 1 according to the embodiment can be formed particularly efficiently.

FIG. 3 is a plan view conceptually showing the structure of the magnetic sensor according to another embodiment of the present invention. FIG. 4 is a cross-sectional view taken along the line V2-V2 of FIG. The magnetic sensor 1A shown in FIGS. 3 and 4 includes a magnetoresistive effect element 11 and a magnetic shield 15 similar to the magnetic sensor 1 shown in FIG. 1, and further, between the magnetoresistive effect element 11 and the magnetic shield 15. A magnetic equilibrium coil (spiral coil) 16 having a spiral shape is provided. In FIG. 3, the outer shape of the magnetic equilibrium coil 16 is shown by a thick broken line. The coil wiring is arranged so as to orbit in the XY plane of the region indicated by the broken line. In FIG. 4, the cross sections of the plurality of rotating coil wirings in the magnetic equilibrium coil 16 are shown side by side in the Y1-Y2 directions. The magnetic equilibrium coil 16 is located between the magnetoresistive effect element 11 and the magnetic shield 15, so that an induced magnetic field that cancels an external magnetic field applied in a state of being attenuated by the magnetic shield 15 is generated with a relatively small current. Can be caused by. Therefore, it is possible to operate the magnetically balanced magnetic sensor with low power consumption.

In the above embodiment, the case where the magnetoresistive effect element 14 to the magnetic resistance effect element 11 included in the magnetic sensors 1 and 1A is composed of a GMR element is taken as a specific example, but the present invention is not limited to this. In one example without limitation, the magnetoresistive element is one selected from the group consisting of an anisotropic magnetoresistive element (AMR element), a giant magnetoresistive element (GMR element), and a tunnel magnetoresistive element (TMR element). It consists of the above elements.

When the fixed layer of each GMR element constituting the magnetic resistance effect element 11 to the magnetic resistance effect element 14 included in the magnetic sensor 1 has a self-pin structure, the fixation of the fixed layer may be performed by film formation in a magnetic field. It can be formed and does not require heat treatment in a magnetic field after film formation. Therefore, GMR elements having different magnetization directions of the fixed layer can be arranged on the same substrate, and a full bridge circuit can be configured on one substrate.

The magnetic sensors 1, 1A provided with the magnetoresistive element according to the embodiment of the present invention can be suitably used as a current sensor.

Specific examples of the current sensor according to the embodiment of the present invention include a magnetically proportional current sensor and a magnetically balanced current sensor.

A specific example of the magnetic proportional current sensor is the case where the magnetic sensor 1 shown in FIGS. 1 and 2 is used. In such a current sensor, the measured current Io is located above FIG. 2 (Z1 side in the Z1-Z2 direction). The current line 40 through which the current flows is located so as to extend in the X1-X2 direction (see FIG. 1). The induced magnetic field of the measured current Io, which is the measured magnetic field, is applied to the magnetoresistive element 11 in the direction along the sensitivity axial direction P (Y1-Y2 direction). Since a part of the magnetic field to be measured passes through the magnetic shield 15 having a higher magnetic permeability, the strength of the magnetic field to be measured substantially applied to the magnetoresistive sensor 11 can be reduced. Therefore, it is possible to expand the measurement range of the magnetic sensor 1. Moreover, since the magnetic shield 15 has the protruding portion 15P, the influence of the recirculation magnetic field RM0 based on the residual magnetization M0 of the magnetic shield 15 on the magnetoresistive effect element 11 is suppressed.

In a preferred example, the magnetic proportional current sensor 1 includes four magnetoresistive effect elements (magnetoresistive element 11 to 14), and has a potential difference according to a measured magnetic field composed of an induced magnetic field of the measured current Io. Has a magnetic field detection bridge circuit with two outputs to produce (see FIG. 1). In the magnetic proportional current sensor 1 having this bridge circuit, the measured current Io is measured by the potential difference output from the magnetic field detection bridge circuit according to the measured magnetic field.

A specific example of the magnetically balanced current sensor is the case where the magnetic sensor 1A shown in FIGS. 3 and 4 is used. In such a current sensor, the measured current Io is located above FIG. 4 (Z1 side in the Z1-Z2 direction). The current line 40 through which the current flows is located so as to extend in the X1-X2 direction. The induced magnetic field of the measured current Io, which is the measured magnetic field, is applied to the magnetoresistive effect element 11 in the direction along the sensitivity axial direction P (Y1-Y2 direction). Since a part of the magnetic field to be measured passes through the magnetic shield 15 having a higher magnetic permeability, the strength of the magnetic field to be measured substantially applied to the magnetoresistive sensor 11 can be reduced. Therefore, the amount of current flowing through the magnetic equilibrium coil 16 can be reduced in order to generate an induced magnetic field that cancels the magnetic field due to the measured current Io substantially applied to the magnetoresistive effect element 11, and the current can be reduced. Power saving of the sensor is realized. Moreover, since the magnetic shield 15 has the protruding portion 15P, the influence of the recirculation magnetic field RM0 based on the residual magnetization M0 of the magnetic shield 15 on the magnetoresistive effect element 11 is suppressed.

In a preferred example, the magnetically balanced current sensor comprises four magnetic resistance effect elements (magnetic resistance effect element 11 to 14), and is a measured magnetic field composed of an induced magnetic field from the measured current Io and the measured magnetic field. It has a magnetic field detection bridge circuit with two outputs that produce a potential difference depending on the induced magnetic field from the magnetic equilibrium coil 16 applied to cancel the magnetic field (see FIG. 3). In the magnetic balance type current sensor having this bridge circuit, the measured current Io is measured based on the current flowing through the magnetic balance coil 16 when the potential difference output from the magnetic field detection bridge circuit becomes zero.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention. For example, the protruding portion 15P does not have to be composed of only the base layer 151. It has a tapered structure in which the length of the soft magnetic layer 152 in the first direction (Y1-Y2 direction) becomes longer as it becomes proximal to the magnetoresistive element 11 (Z1-Z2 direction Z2 side). May be good.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

(Example 1)
A magnetic balance type magnetic sensor having a structure similar to the cross-sectional structure shown in FIG. 2 was manufactured. The magnetoresistive element was a GMR element. The magnetic shield has a planar shape of 800 μm × 200 μm and is made of NiFe, and a base layer having a thickness of 100 nm is formed by sputtering. It was laminated by electroplating, and an oxidation protective layer made of Ta and having a thickness of 10 nm was formed by sputtering. As a result, a magnetic shield having a shape in which protrusions of 30 μm are located from both sides of the main body in the Y1-Y2 direction (when viewed from the Z1-Z2 direction) in a plan view was obtained. By changing the distance between the magnetic seal and the coil (distance in the Y1-Y2 direction) in the process of manufacturing the magnetic sensor, the distance D1 between the magnetic shield and the GMR element (distance in the Y1-Y2 direction) can be increased. Multiple different magnetic sensors in the range of about 8 μm to about 11.5 μm were made.

(Comparative Example 1)
A magnetic sensor having the same structure as that of the first embodiment but having a shape in which the magnetic shield does not have a protruding portion was manufactured.

(Measurement Example 1) Measurement of zero magnetic field hysteresis The external magnetic field is changed by setting the maximum strength (maximum applied magnetic field) of the applied external magnetic field to ± 18 mT for each of the magnetic sensor manufactured by the example and the magnetic sensor manufactured by the comparative example. While measuring the hysteresis loop. From this hysteresis loop, zero magnetic field hysteresis ZH (unit:% / FS) was measured. Zero magnetic field hysteresis ZH is the magnitude of the output at zero magnetic field (positive maximum) with respect to the maximum value of the output in the full bridge output curve (value when positive maximum magnetic field is applied-value when negative maximum magnetic field is applied). It is the ratio (unit:%) of the value when the magnetic field is applied to the applied magnetic field of zero-the value when the negative maximum magnetic field is applied to the applied magnetic field of zero. The measurement results are shown in FIG.

As shown in FIG. 5, in the magnetic sensor according to the comparative example, the zero magnetic field hysteresis ZH was in the range of + 0.05% to −0.2%. When the distance D1 was small, that is, the closer it was to 8 μm, the zero magnetic field hysteresis ZH tended to be a negative value. This is because the recirculation magnetic field based on the residual magnetization of the magnetic shield is applied to the GMR element in antiparallel to the direction of the remanent magnetization even when the applied strength of the external magnetic field is zero, and the intensity of this recirculation magnetic field is the GMR element. This is because the closer to the magnetic shield, the higher the value.

On the other hand, in the magnetic sensor according to the embodiment, the zero magnetic field hysteresis ZH was in the range of + 0.05% to −0.05%, and the absolute value of the zero magnetic field hysteresis ZH tended to be smaller on the minus side. This is because the magnetic shield has a shape having a protruding portion, so that the influence of the reflux magnetic field is relatively reduced.

The magnetic sensor provided with the magnetoresistive effect element according to the embodiment of the present invention is suitably used as a component of a current sensor of infrastructure equipment such as a columnar transformer and a component of a current sensor of an electric vehicle, a hybrid car, or the like. sell.

1,1A Magnetic sensor 11, 12, 13, 14 Magnetic resistance effect element 5, 6, 7, 8 Wiring 5a Input terminal 6a Ground terminal 7a First midpoint potential measurement terminal 8a Second midpoint potential measurement terminal 40 Current line Io Measured current IM Insulation layer 15 Magnetic shield 150 Main body 15P Protruding part 15PE Protruding tip 151 Underlayer layer 152 Soft magnetic layer 16 Magnetic equilibrium coil (spiral coil)
PL Oxidation protection layer 29 Substrate M0 Remaining magnetization RM0 Reflux magnetic field

Claims (6)

It includes a magnetoresistive sensor having a sensitivity axis in the first direction, and a magnetic shield that is spaced above the magnetoresistive sensor and attenuates the strength of the magnetic field to be measured applied to the magnetoresistive sensor. It is a magnetic sensor
The magnetic shield has a main body portion and a protruding portion protruding from the main body portion in the first direction, and the main body portion is longitudinally oriented in a second direction orthogonal to the first direction in a plan view. A magnetic sensor characterized in that the protruding portion has a portion thinner than the main body portion. The magnetic sensor according to claim 1, wherein the protruding portion is located at the lower end of the magnetic shield. The magnetic sensor according to claim 1 or 2, wherein the entire magnetoresistive sensor overlaps the main body portion of the magnetic shield in a plan view. The magnetic sensor according to any one of claims 1 to 3 , further comprising a magnetic equilibrium coil and measuring the strength of the measured magnetic field based on a current flowing through the magnetic equilibrium coil. The magnetic sensor according to claim 4, wherein the magnetic balancing coil is a spiral coil and is located between the magnetoresistive sensor and the magnetic shield. The magnetic sensor according to any one of claims 1 to 5, wherein the magnetic sensor is a current sensor whose measured magnetic field is an induced magnetic field of a measured current.

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