阅读说明：本技术 磁传感器及电流传感器 (Magnetic sensor and current sensor ) 是由 久保田将司 牛见义光 原铁三 于 2018-12-25 设计创作，主要内容包括：磁传感器(1)具备：基板；以及磁阻元件部,其在基板上被设置为具有规定的磁敏方向,在与磁敏方向正交的方向上被施加偏置磁场,磁阻元件部包括具有负的磁致伸缩常数的磁性层,在对基板沿与磁敏方向平行的方向作用了拉伸应力的情况下,在与偏置磁场的方向平行的方向上表现出磁性层的应力诱导各向异性。(A magnetic sensor (1) is provided with: a substrate; and a magnetoresistive element unit that is provided on the substrate so as to have a predetermined magnetosensitive direction and is applied with a bias magnetic field in a direction orthogonal to the magnetosensitive direction, the magnetoresistive element unit including a magnetic layer having a negative magnetostriction constant, and exhibiting stress-induced anisotropy of the magnetic layer in a direction parallel to the direction of the bias magnetic field when a tensile stress acts on the substrate in the direction parallel to the magnetosensitive direction.)

1. A magnetic sensor is provided with:

a substrate; and

a magnetoresistive element section provided on the substrate so as to have a predetermined magnetosensitive direction, and to which a bias magnetic field is applied in a direction orthogonal to the magnetosensitive direction,

the magnetoresistive element portion includes a magnetic film having a negative magnetostriction constant,

when a tensile stress acts on the substrate in a direction parallel to the magnetosensitive direction, the stress-induced anisotropy of the magnetic film is expressed in a direction parallel to the direction of the bias magnetic field.

2. A magnetic sensor is provided with:

a substrate; and

a magnetoresistive element section provided on the substrate so as to have a predetermined magnetosensitive direction, and to which a bias magnetic field is applied in a direction orthogonal to the magnetosensitive direction,

the magnetoresistive element portion includes a magnetic film having a positive magnetostriction constant,

when a compressive stress acts on the substrate in a direction parallel to the magnetosensitive direction, the stress-induced anisotropy of the magnetic film is expressed in a direction parallel to the direction of the bias magnetic field.

3. A magnetic sensor according to claim 1 or 2,

the substrate has a strip shape with a long side direction,

the magnetic sensitive direction is parallel to the long side direction.

4. A magnetic sensor according to any one of claims 1 to 3,

the magnetoresistive element section includes a first magnetoresistive element, a second magnetoresistive element, a third magnetoresistive element, and a fourth magnetoresistive element,

the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element are arranged in a row in the order of the third magnetoresistive element, the fourth magnetoresistive element, the second magnetoresistive element, and the first magnetoresistive element along a direction parallel to the direction of the bias magnetic field, and are electrically connected in series,

detecting a midpoint potential of the first magnetoresistive element and the second magnetoresistive element from a connection portion connecting the first magnetoresistive element and the second magnetoresistive element,

the midpoint potential of the third magnetoresistive element and the midpoint potential of the fourth magnetoresistive element are detected from a connection portion connecting the third magnetoresistive element and the fourth magnetoresistive element.

5. A magnetic sensor according to any one of claims 1 to 3,

the magnetoresistive element section includes first magnetoresistive elements, second magnetoresistive elements, third magnetoresistive elements, and fourth magnetoresistive elements arranged in a matrix,

the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element form a full bridge circuit.

6. A magnetic sensor according to claim 5,

the first magnetoresistive element and the second magnetoresistive element are arranged in a row along a direction parallel to the direction of the bias magnetic field and constitute a first half-bridge circuit,

the third magnetoresistive element and the fourth magnetoresistive element are arranged in a row along a direction parallel to the direction of the bias magnetic field and constitute a second half-bridge circuit,

the full bridge circuit is constituted by the first half bridge circuit and the second half bridge circuit,

detecting a midpoint potential of the first magnetoresistive element and the second magnetoresistive element from a connection portion connecting the first magnetoresistive element and the second magnetoresistive element,

the midpoint potential of the third magnetoresistive element and the midpoint potential of the fourth magnetoresistive element are detected from a connection portion connecting the third magnetoresistive element and the fourth magnetoresistive element.

7. A current sensor is provided with:

a bus bar through which a current to be measured flows; and

a magnetic sensor as claimed in any one of claims 1 to 6.

Technical Field

The present disclosure relates to a magnetic sensor and a current sensor.

Background

Conventionally, in a magnetic sensor using the magnetoresistance effect, various methods for controlling magnetic anisotropy have been proposed in order to improve sensor characteristics and reliability. For example, Japanese patent application laid-open No. 7-244142 (patent document 1) and Japanese patent application laid-open No. 2002-189067 (patent document 2) disclose methods for inducing anisotropy by utilizing stress based on the inverse magnetostriction effect.

In the magnetic sensor disclosed in patent document 1, in the case of a magnetic sensor including a sensor pattern using a ferromagnetic metal thin film, when the ferromagnetic metal thin film has a positive magnetostriction constant, a continuous tensile stress is applied to the hard magnetization direction of the sensor pattern, and the magnetization direction of the ferromagnetic metal thin film changes between the easy magnetization direction and the hard magnetization direction depending on the strength of a magnetic field. On the other hand, when the ferromagnetic metal thin film has a negative magnetostriction constant, a continuous compressive stress is applied to the hard magnetization direction of the sensor pattern. This can achieve high sensitivity in a minute magnetic field.

The magnetic sensor disclosed in patent document 2 is disposed on a piezoelectric substrate, and a voltage is applied to the piezoelectric substrate to apply a strain to the magnetic sensor. This changes the anisotropy inside the magnetic material constituting the magnetic sensor, and changes the sensor characteristics. As a result, the operating point can be determined at a point where the magnetic sensor has high sensitivity.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 7-244142

Patent document 2: japanese laid-open patent publication No. 2002-189067

Disclosure of Invention

Problems to be solved by the invention

However, in the magnetic sensor disclosed in patent document 1, when the stress is varied by an external input or the like even when a continuous stress is applied, stress-induced magnetic anisotropy is exhibited in a direction parallel to the magnetosensitive direction. This causes the resistance value of the magnetic sensor to fluctuate in the zero magnetic field.

The magnetic sensor disclosed in patent document 2 has a structure using a piezoelectric element, and therefore, the structure becomes large, and the manufacturing cost increases.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a magnetic sensor and a current sensor capable of improving reliability against stress fluctuations.

Means for solving the problems

A magnetic sensor according to a first aspect of the present disclosure includes: a substrate; and a magnetoresistive element portion provided on the substrate so as to have a predetermined magnetosensitive direction and to which a bias magnetic field is applied in a direction orthogonal to the magnetosensitive direction, wherein the magnetoresistive element portion includes a magnetic layer having a negative magnetostriction constant, and when a tensile stress acts on the substrate in a direction parallel to the magnetosensitive direction, a stress-induced anisotropy of the magnetic layer is exhibited in a direction parallel to the direction of the bias magnetic field.

A magnetic sensor according to a second aspect of the present disclosure includes: a substrate; and a magnetoresistive element portion provided on the substrate so as to have a predetermined magnetosensitive direction and to which a bias magnetic field is applied in a direction orthogonal to the magnetosensitive direction, wherein the magnetoresistive element includes a magnetic layer having a positive magnetostriction constant, and when a compressive stress acts on the substrate in a direction parallel to the magnetosensitive direction, a stress-induced anisotropy of the magnetic layer is expressed in a direction parallel to the direction of the bias magnetic field.

In the magnetic sensor according to the first or second aspect of the present disclosure, the substrate preferably has an elongated shape having a longitudinal direction. In this case, the magnetic sensing direction is preferably parallel to the longitudinal direction.

In the magnetic sensor according to the first and second aspects of the present disclosure, the magnetoresistive element section may include a first magnetoresistive element, a second magnetoresistive element, a third magnetoresistive element, and a fourth magnetoresistive element electrically connected in series, and the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element may be arranged in a row along a direction parallel to the direction of the bias magnetic field. In this case, it is preferable that a midpoint potential of the first magnetoresistive element and the second magnetoresistive element is detected from a connection portion connecting the first magnetoresistive element and the second magnetoresistive element, and a midpoint potential of the third magnetoresistive element and the fourth magnetoresistive element is detected from a connection portion connecting the third magnetoresistive element and the fourth magnetoresistive element.

In the magnetic sensor according to the first and second aspects of the present disclosure, the magnetoresistive element section may include first, second, third, and fourth magnetoresistive elements arranged in a matrix. In this case, it is preferable that the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element constitute a full bridge circuit.

In the magnetic sensor according to the first and second aspects of the present disclosure, the first magnetoresistive element and the second magnetoresistive element may be arranged in a row along a direction parallel to the direction of the bias magnetic field, and may form a first half-bridge circuit. The third magnetoresistive element and the fourth magnetoresistive element may be arranged in a row along a direction parallel to the direction of the bias magnetic field, and may form a second half-bridge circuit. In this case, it is preferable that the full-bridge circuit is configured by the first half-bridge circuit and the second half-bridge circuit. Preferably, a midpoint potential of the first magnetoresistive element and the second magnetoresistive element is detected from a connection portion connecting the first magnetoresistive element and the second magnetoresistive element, and a midpoint potential of the third magnetoresistive element and the fourth magnetoresistive element is detected from a connection portion connecting the third magnetoresistive element and the fourth magnetoresistive element.

The current sensor of the present disclosure includes a bus bar through which a current to be measured flows, and the magnetic sensor described above.

Effects of the invention

According to the present disclosure, a magnetic sensor and a current sensor capable of improving reliability against stress fluctuation can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view showing a magnetic sensor according to embodiment 1.

Fig. 2 is a schematic cross-sectional view showing a magnetic sensor element according to embodiment 1.

Fig. 3 is a diagram showing a relationship between the direction of the bias magnetic field applied to the magnetic sensor element and the magnetosensitive direction in the magnetic sensor of embodiment 1.

Fig. 4 is a diagram showing forces acting when the magnetic sensor element of embodiment 1 is stretched in the magnetosensitive direction.

Fig. 5 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element unit, a force acting on each magnetoresistive element when a magnetic sensor element is stretched, a magnetization direction of each magnetoresistive element, and the like in embodiment 1.

Fig. 6 is a diagram showing changes in the resistance of the plurality of magnetoresistive elements in the case where the magnetic sensor element of embodiment 1 is stretched in the magnetosensitive direction.

Fig. 7 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements, a midpoint potential between the first and second magnetoresistive elements, a midpoint potential between the third and fourth magnetoresistive elements, and a difference between the midpoint potentials, before the magnetic sensor element of embodiment 1 is stretched in the magnetic sensing direction.

Fig. 8 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements after the magnetic sensor element of embodiment 1 is pulled in the magnetosensitive direction, the midpoint potential of the first and second magnetoresistive elements, the midpoint potential of the third and fourth magnetoresistive elements, and the difference between the midpoint potentials.

Fig. 9 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element unit, a force acting on each magnetoresistive element when a magnetic sensor element is stretched, a magnetization direction of each magnetoresistive element, and the like in embodiment 2.

Fig. 10 is a diagram showing changes in the resistance of the plurality of magnetoresistive elements in the case where the magnetic sensor element of embodiment 2 is stretched in the magnetosensitive direction.

Fig. 11 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements, a midpoint potential between the first and second magnetoresistive elements, a midpoint potential between the third and fourth magnetoresistive elements, and a difference between the midpoint potentials, before the magnetic sensor element of embodiment 2 is stretched in the magnetic sensing direction.

Fig. 12 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements after the magnetic sensor element of embodiment 2 is pulled in the magnetic sensing direction, the midpoint potential of the first and second magnetoresistive elements, the midpoint potential of the third and fourth magnetoresistive elements, and the difference between the midpoint potentials.

Fig. 13 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element unit according to embodiment 3, forces acting on the respective magnetoresistive elements when the magnetoresistive elements are stretched, magnetization directions of the respective magnetoresistive elements, and the like.

Fig. 14 is a diagram showing changes in the resistance of the plurality of magnetoresistive elements in the case where the magnetic sensor element of embodiment 3 is stretched in the magnetosensitive direction.

Fig. 15 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements, a midpoint potential between the first and second magnetoresistive elements, a midpoint potential between the third and fourth magnetoresistive elements, and a difference between the midpoint potentials, before the magnetic sensor element of embodiment 3 is pulled in the magnetic sensing direction.

Fig. 16 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements after the magnetic sensor element of embodiment 3 is pulled in the magnetic sensing direction, the midpoint potential of the first and second magnetoresistive elements, the midpoint potential of the third and fourth magnetoresistive elements, and the difference between the midpoint potentials.

Fig. 17 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element section of a comparative example, and forces acting on the respective magnetoresistive elements and magnetization directions of the respective magnetoresistive elements when the magnetoresistive elements are stretched.

Fig. 18 is a diagram showing changes in the resistances of the plurality of magnetoresistive elements in the case where the magnetic sensor element of the comparative example is stretched in the magnetosensitive direction.

Fig. 19 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements, a midpoint potential between the first and second magnetoresistive elements, a midpoint potential between the third and fourth magnetoresistive elements, and a difference between the midpoint potentials, before the magnetic sensor element of the comparative example is stretched in the magnetic sensing direction.

Fig. 20 is a diagram showing a force acting on each of the first to fourth magnetoresistive elements after the magnetic sensor element of the comparative example is stretched in the magnetic sensing direction, the midpoint potential of the first and second magnetoresistive elements, the midpoint potential of the third and fourth magnetoresistive elements, and the difference between the midpoint potentials.

Fig. 21 is a diagram showing forces acting when the magnetic sensor element of the modification is compressed in the magnetism sensing direction.

Fig. 22 is a perspective view of a current sensor according to embodiment 4.

Fig. 23 is a plan view of a current sensor according to embodiment 4.

Fig. 24 is a front view of a current sensor according to embodiment 4.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, the same or common portions are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

(embodiment mode 1)

Fig. 1 is a schematic cross-sectional view showing a magnetic sensor according to embodiment 1. A magnetic sensor 100 according to embodiment 1 will be described with reference to fig. 1.

As shown in fig. 1, a magnetic sensor 100 according to embodiment 1 includes a magnetic sensor element 1, a lead frame 2, a bonding member 3, a bonding wire 4, and a mold member 5. The magnetic sensor element 1 is molded by the molding member 5 in a state of being bonded to the lead frame 2 by the bonding member 3. The magnetic sensor element 1 is electrically connected to the lead frame 2 by bonding wires 4.

When the direction parallel to the direction in which the lead frame 2, the bonding member 3, and the magnetic sensor element 1 are aligned is taken as the thickness direction, the thickness T1 of the molding member 5 on the side where the bonding member 3 and the magnetic sensor element 1 are located is thicker than the thickness of the molding member 5 on the side opposite to the side where the bonding member 3 and the magnetic sensor element 1 are located, with respect to the center line C L of the lead frame 2 passing through the center of the lead frame 2 in the thickness direction.

Fig. 2 is a schematic cross-sectional view showing a magnetic sensor element according to embodiment 1. The magnetic sensor element 1 of embodiment 1 will be described with reference to fig. 2.

As shown in fig. 2, the magnetic sensor element 1 of embodiment 1 is, for example, an AMR element. The magnetic sensor element 1 includes a substrate 10, a laminated body 11 as a magnetoresistive element portion, a pair of electrode portions 15, and a protective layer 16.

The substrate 10 is, for example, a Si substrate with a thermally oxidized film. The substrate 10 may be an insulating substrate such as a glass substrate, or may be a plate-like member formed with an insulating film.

The laminate 11 is provided on the main surface of the substrate 10. As described later, the laminated body 11 is formed into a desired pattern. The laminate 11 includes a base film 12, a magnetic film 13, and a protective film 14. These base film 12, magnetic film 13, and protective film 14 are stacked in this order from the substrate 10 side.

The base film 12 is formed on a thermally oxidized film having high insulation properties. As the base film 12, a metal film made of a metal such as Ta, W, Mo, Ti, or Ru, or a laminated film obtained by laminating these metal films is used. The base film 12 is provided to grow the magnetic film 13 appropriately. In the case where the magnetic film 13 can be grown appropriately without using the base film 12, the base film 12 may be omitted.

The magnetic film 13 is formed on the base film 12. The magnetic film 13 has a negative magnetostriction constant λ. The magnetic film 13 is formed so that the magnetostriction constant lambda becomes-1 ppm < lambda < 0 ppm. The magnetic film 13 is made of, for example, an alloy including Ni and Fe. In this case, the magnetostriction constant λ of the magnetic film 13 can be appropriately set by adjusting the composition of Ni.

The protective film 14 is formed on the magnetic film 13. As the protective film 14, a metal film made of a metal such as Ta, W, Mo, Ti, or Ru, or a laminated film obtained by laminating these metal films is used. The protective film 14 is provided to protect the magnetic film 13. Note that the protective film 14 may be omitted when the device characteristics are not affected.

The pair of electrode portions 15 is provided at both ends of the stacked body 11. The electrode portion 15 is made of a metal material having good conductivity such as Al, Cu, and Au. In order to improve the adhesion between the stacked body 11 and the electrode portion 15, an adhesion layer made of Ti, Cr, or the like may be provided between the stacked body 11 and the electrode portion 15.

The protective layer 16 is provided so as to cover the stacked body 11 and the pair of electrode portions 15. The protective layer 16 is provided with a contact hole 16a so that a part of the pair of electrode portions 15 is exposed. One end of the bonding wire 4 is inserted into the contact hole 16a, and one end of the bonding wire 4 is connected to the electrode portion 15. The other end side of the bonding wire 4 is connected to the lead frame 2.

As the protective layer 16, SiO can be used₂、TiO₂、ZrO₂、Al₂O₃、HfO₂And the like, which are highly insulating materials. The protective layer 16 is provided to prevent oxidation and corrosion of the laminate 11 and the like. The protective layer 16 may be omitted.

Fig. 3 is a diagram showing a relationship between the direction of the bias magnetic field applied to the magnetic sensor element and the magnetosensitive direction in the magnetic sensor of embodiment 1.

As shown in fig. 3, the magnetic sensor 100 has a strip shape having a long side direction (DR1 direction) and a short side direction (DR2 direction) in a plan view. Similarly, the magnetic sensor element 1 also has a strip shape having a long side direction (DR1 direction) and a short side direction (DR2 direction) in a plan view. The magnetic sensor element 1 has a magnetic sensitive direction in a direction parallel to the longitudinal direction.

The magnetic sensor 100 includes a magnetic field applying unit (not shown) for applying a bias magnetic field to the magnetic sensor element 1. The magnetic field applying unit is constituted by, for example, a permanent magnet (not shown). The permanent magnet is molded by the molding member 5 together with the magnetic sensor element 1. The magnetic field applying unit applies a bias magnetic field in a direction (direction DR 2) orthogonal to the magnetosensitive direction.

In manufacturing the magnetic sensor 100, first, the substrate 10 is prepared. Next, the stacked body 11 having a desired pattern is formed on the substrate 10 by photolithography, dry etching, or the like.

Next, the pair of electrode portions 15 is formed by photolithography, vapor deposition, sputtering, or the like. Next, the protective layer 16 is formed so as to cover the stacked body 11 and the pair of electrode portions 15 by sputtering, CVD, or the like.

Next, the contact hole 16a is formed by photolithography, dry etching, or the like. Next, the substrate 10 is singulated into pieces having a desired size using a dicing apparatus, thereby forming the magnetic sensor element 1.

Next, the magnetic sensor element 1 is fixed to the lead frame 2 using the bonding member 3. Next, the pair of electrode portions 15 is electrically connected to the lead frame 2 by the bonding wires 4. In this state, the lead frame 2 and the magnetic sensor element 1 are molded together with a permanent magnet for applying a bias magnetic field by the molding member 5. Thereby, the magnetic sensor 100 is manufactured.

The magnetic sensor element 1 is molded by applying a tensile stress (initial stress) to the magnetic sensor element 1 in the longitudinal direction parallel to the longitudinal direction (DR1 direction) by utilizing the difference in thermal expansion coefficient between the molding member 5 and the magnetic sensor element 1. By molding in this manner, the longitudinal direction, i.e., the direction parallel to the magnetosensitive direction, is dominant for the direction of the initial stress and the direction of the stress fluctuation due to the use condition in the state of being exposed to the ambient temperature.

Fig. 4 is a diagram showing forces acting when the magnetic sensor element of embodiment 1 is stretched in the magnetosensitive direction. Referring to fig. 4, a force acting when the magnetic sensor element of embodiment 1 is stretched in the magnetosensitive direction will be described.

As shown in fig. 4, when the magnetic sensor element 1 is stretched in a direction parallel to the magnetic sensing direction, that is, when a tensile stress acts on the magnetic sensor element 1 in a direction parallel to the magnetic sensing direction, both end sides of the magnetic sensor element 1 in the direction parallel to the magnetic sensing direction are stretched outward, and the center portion of the magnetic sensor element 1 parallel to the magnetic sensing direction is compressed in a direction orthogonal to the magnetic sensing direction. Therefore, when the magnetoresistive element portion is disposed in the center portion of the magnetic sensor element 1, the direction of the stress-induced anisotropy of the magnetic film 13, which is exhibited by the inverse magnetostrictive effect, is parallel to the direction of the bias magnetic field.

Fig. 5 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element, a force acting on each magnetoresistive element when the magnetic sensor element is stretched, a magnetization direction of each magnetoresistive element, and the like in embodiment 1.

As shown in fig. 5, the magnetic sensor element 1 includes a first magnetoresistive element E1, a second magnetoresistive element E2, a third magnetoresistive element E3, and a fourth magnetoresistive element E4 arranged in a matrix. The first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are composed of a stacked body 11 patterned into a desired shape. The first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are arranged in two rows and two columns to form a full bridge circuit.

The first magnetoresistive element E1 and the third magnetoresistive element E3 are arranged in a line along a direction orthogonal to the direction of the bias magnetic field. The second magnetoresistive element E2 and the fourth magnetoresistive element E4 are arranged in a line along a direction orthogonal to the direction of the bias magnetic field.

The first magnetoresistive element E1 and the second magnetoresistive element E2 are arranged in a row along a direction parallel to the direction of the bias magnetic field. The third magnetoresistive element E3 and the fourth magnetoresistive element E4 are arranged in a row along a direction parallel to the direction of the bias magnetic field.

The first magnetoresistive element E1 and the second magnetoresistive element E2 constitute a first half-bridge circuit. The third magnetoresistive element E3 and the fourth magnetoresistive element E4 constitute a second half-bridge circuit. The first half-bridge circuit and the second half-bridge circuit constitute a full-bridge circuit.

One end side of the first magnetoresistive element E1 is electrically connected to an electrode pad Vdd for applying a voltage through a wiring pattern. The other end side of the first magnetoresistive element E1 is connected to one end side of the second magnetoresistive element E2 via a wiring pattern, and is electrically connected to an electrode pad S1 for detecting the midpoint potential Vout1 of the first magnetoresistive element E1 and the second magnetoresistive element E2.

One end side of the second magnetoresistive element E2 is connected to the other end side of the first magnetoresistive element E1 via a wiring pattern, and is electrically connected to the electrode pad S1. The other end side of the second magnetoresistive element E2 is electrically connected to an electrode pad G connected to a ground line through a wiring pattern.

One end side of the third magnetoresistive element E3 is electrically connected to the electrode pad Vdd via a power distribution pattern. The other end side of the third magnetoresistive element E3 is connected to one end side of the fourth magnetoresistive element E4 by a wiring pattern, and is electrically connected to an electrode pad S2 for detecting a midpoint potential Vout2 of the third magnetoresistive element E3 and the fourth magnetoresistive element E4.

One end side of the fourth magnetoresistive element E4 is connected to the other end side of the third magnetoresistive element E3 via a wiring pattern, and is electrically connected to the electrode pad S2. The other end side of the fourth magnetoresistive element E4 is electrically connected to the electrode pad G via a wiring pattern.

When a voltage is applied between the electrode pad Vdd and the electrode pad G, the midpoint potential Vout1 and the midpoint potential Vout2 are extracted from the electrode pad S1 and the electrode pad S2 in accordance with the magnetic field strength.

Here, when the resistance of the first magnetoresistive element E1 is R1, the resistance of the second magnetoresistive element E2 is R2, the resistance of the third magnetoresistive element E3 is R3, and the resistance of the fourth magnetoresistive element E4 is R4, the midpoint potential Vout1 and the midpoint potential Vout2 are expressed by the following expressions (1) and (2). The values of R1, R2, R3, and R4 vary depending on the tensile stress applied to the magnetic sensor element 1.

The midpoint potential Vout1 is Vdd × R2/(R1+ R2) · (formula 1)

The midpoint potential Vout2 is Vdd × R4/(R3+ R4) · (formula 2)

When the magnetic sensor element 1 is stretched in the magnetosensitive direction, as shown in fig. 5, a stress Bstress acts on each of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 in a direction parallel to the direction of the bias magnetic field. Thereby, the direction of the magnetization M of the magnetic body moves from the direction parallel to the bias magnetic field Bbias to the direction in which the bias magnetic field Bbias and the stress Bstress are combined. As a result, the resistances of the magnetoresistive elements of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 also change.

Fig. 6 is a diagram showing changes in the resistance of the plurality of magnetoresistive elements in the case where the magnetic sensor element of embodiment 1 is stretched in the magnetosensitive direction. In fig. 6, the force acting on the magnetic sensor element before stretching is shown by a broken line, the force acting on the magnetic sensor element after stretching is shown by a solid line, and the resistances of the magnetoresistive elements before and after stretching are shown by numerical values (relative ratios).

As shown in fig. 6, before the magnetic sensor element 1 is stretched in the magnetosensitive direction, the stress distribution in the direction parallel to the magnetosensitive direction (the short-side direction) is formed into a convex shape in which the central portion in the short-side direction is increased by the initial stress. In this case, the first magnetoresistive element E1 and the second magnetoresistive element E2, and the third magnetoresistive element E3 and the fourth magnetoresistive element E4 are disposed at equal distances in the short direction from the center in the short direction. Accordingly, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are substantially equal to each other. In this case, the resistance R1 of the first magnetoresistive element E1, the resistance R2 of the second magnetoresistive element E2, the resistance R3 of the third magnetoresistive element E3, and the resistance R4 of the fourth magnetoresistive element E4 are set to 3.

On the other hand, after the magnetic sensor element 1 is stretched in the magnetosensitive direction from the initial state, that is, when a tensile stress acts on the substrate 10 in a direction parallel to the magnetosensitive direction, a stress Bstress acts on each magnetoresistive element. Thus, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 change before the magnetic sensor element 1 is stretched in the magnetic sensing direction.

Specifically, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 change from 3 to 2. The resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 change from 3 to 4.

On the other hand, when the magnetic sensor element 1 is stretched in the magnetosensitive direction, the central portion of the magnetic sensor element 1 parallel to the magnetosensitive direction is compressed in the direction orthogonal to the magnetosensitive direction. Therefore, when the magnetoresistive element portion is disposed in the center portion of the magnetic sensor element 1, the direction of the stress-induced anisotropy of the magnetic film 13, which is expressed by the inverse magnetostrictive effect, is parallel to the direction of the bias magnetic field as described above. This can suppress variations in resistance of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 due to stress-induced anisotropy.

Fig. 7 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element, the midpoint potential between the first magnetoresistive element and the second magnetoresistive element, the midpoint potential between the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the midpoint potentials before the magnetic sensor element of embodiment 1 is pulled in the magnetic sensing direction.

As shown in fig. 7, before the magnetic sensor element 1 is stretched in the magnetic sensing direction, as described above, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 have the same value, and the resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 have the same value. Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have the same value. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.5. As a result, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, becomes 0.

Fig. 8 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element after the magnetic sensor element of embodiment 1 is stretched in the magnetosensitive direction, the midpoint potential of the first magnetoresistive element and the second magnetoresistive element, the midpoint potential of the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the midpoint potentials.

As shown in fig. 8, after the magnetic sensor element 1 is stretched in the magnetosensitive direction, as described above, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 have the same value, and the resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 have the same value. Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have the same value. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.5. As a result, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, becomes 0.

As a result, in the magnetic sensor according to embodiment 1, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, can be suppressed from changing before and after stretching.

As described above, the magnetic sensor 100 according to embodiment 1 includes a magnetoresistive element that is provided on a substrate so as to have a predetermined magnetosensitive direction and is applied with a bias magnetic field in a direction orthogonal to the magnetosensitive direction, and includes a magnetic film having a negative magnetostriction constant, and when a tensile stress acts on the substrate in a direction parallel to the magnetosensitive direction, the magnetic sensor exhibits stress-induced anisotropy of the magnetic film in the direction parallel to the direction of the bias magnetic field.

As a result, as described above, it is possible to suppress variations in resistance of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 due to stress-induced anisotropy. This allows the magnetic sensor 100 to have improved reliability against stress fluctuations.

In particular, as described above, in the case where the laminated body 11 as a magnetoresistive element portion includes the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 arranged in a matrix, and the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 form a full bridge circuit, it is possible to more effectively suppress Voff from changing before and after stretching.

In the magnetic sensor 100, the first magnetoresistive element E1 and the second magnetoresistive element E2 are arranged in a row in a direction parallel to the direction of the bias magnetic field, and constitute a first half-bridge circuit, the third magnetoresistive element E3 and the fourth magnetoresistive element E4 are arranged in a row in a direction parallel to the direction of the bias magnetic field, and constitute a second half-bridge circuit, the first half-bridge circuit and the second half-bridge circuit constitute the full-bridge circuit, the midpoint potential of the first magnetoresistive element E1 and the second magnetoresistive element E2 is detected from a connection portion connecting the first magnetoresistive element E1 and the second magnetoresistive element, and the midpoint potential of the third magnetoresistive element E3 and the fourth magnetoresistive element E4 is detected from a connection portion connecting the third magnetoresistive element E3 and the fourth magnetoresistive element E4.

Thus, as described above, before and after stretching, the fluctuation of the midpoint potential Vout1 can be suppressed, and the fluctuation of the midpoint potential Vout2 can also be suppressed.

(embodiment mode 2)

Fig. 9 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element, a force acting on each magnetoresistive element when the magnetic sensor element is stretched, a magnetization direction of each magnetoresistive element, and the like in embodiment 2. A magnetic sensor according to embodiment 2 will be described with reference to fig. 9.

As shown in fig. 9, in the magnetic sensor according to embodiment 2, the arrangement pattern of the plurality of magnetoresistive elements constituting the magnetoresistive element portion is different from that of the magnetic sensor 100 according to embodiment 1. The other structures are substantially the same.

The magnetic sensor element 1A includes a first magnetoresistive element E1, a second magnetoresistive element E2, a third magnetoresistive element E3, and a fourth magnetoresistive element E4 arranged in a matrix. The first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are arranged in two rows and two columns to form a full bridge circuit.

The first magnetoresistive element E1 and the third magnetoresistive element E3 are arranged in a row along a direction parallel to the direction of the bias magnetic field. The second magnetoresistive element E2 and the fourth magnetoresistive element E4 are arranged in a row along a direction parallel to the direction of the bias magnetic field.

The first magnetoresistive element E1 and the second magnetoresistive element E2 are arranged in a line along a direction orthogonal to the direction of the bias magnetic field. The third magnetoresistive element E3 and the fourth magnetoresistive element E4 are arranged in a line along a direction orthogonal to the direction of the bias magnetic field.

The first magnetoresistive element E1 and the second magnetoresistive element E2 constitute a first half-bridge circuit. The third magnetoresistive element E3 and the fourth magnetoresistive element E4 constitute a second half-bridge circuit. The first half-bridge circuit and the second half-bridge circuit constitute a full-bridge circuit.

When a voltage is applied between the electrode pad Vdd and the electrode pad G, the midpoint potential Vout1 and the midpoint potential Vout2 are extracted from the electrode pad S1 and the electrode pad S2 in accordance with the magnetic field strength.

In this case, the midpoint potential Vout1 and the midpoint potential Vout2 are also expressed by the above-described equations (1) and (2) as in embodiment 1.

Fig. 10 is a diagram showing changes in the resistance of the plurality of magnetoresistive elements in the case where the magnetic sensor element of embodiment 2 is stretched in the magnetosensitive direction. In fig. 10, the force acting on the magnetic sensor element before stretching is shown by a broken line, the force acting on the magnetic sensor element after stretching is shown by a solid line, and the resistances of the magnetoresistive elements before and after stretching are shown by numerical values (relative ratios).

As shown in fig. 10, before the magnetic sensor element 1A is stretched in the magnetosensitive direction, the stress distribution in the direction parallel to the magnetosensitive direction (the short-side direction) becomes convex in such a manner that the central portion in the short-side direction becomes larger due to the initial stress. In this case, the first magnetoresistive element E1 and the second magnetoresistive element E2, and the third magnetoresistive element E3 and the fourth magnetoresistive element E4 are disposed equidistantly in the lateral direction from the center in the lateral direction. Accordingly, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are substantially equal to each other. In this case, the resistance R1 of the first magnetoresistive element E1, the resistance R2 of the second magnetoresistive element E2, the resistance R3 of the third magnetoresistive element E3, and the resistance R4 of the fourth magnetoresistive element E4 are set to 3.

On the other hand, after the magnetic sensor element 1A is stretched in the magnetic sensing direction, that is, when a tensile stress acts on the substrate 10 in a direction parallel to the magnetic sensing direction, a stress Bstress acts on each magnetoresistive element. Thus, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 change before the magnetic sensor element 1A is stretched in the magnetic sensing direction.

Specifically, the resistance R1 of the first magnetoresistive element E1 changes from 3 to 2. The resistance R2 of the second magnetoresistive element E2 changes from 3 to 4. The resistance R3 of the third magnetoresistive element E3 changes from 3 to 4. The resistance R4 of the fourth magnetoresistive element E4 changes from 3 to 2.

On the other hand, when the magnetic sensor element 1A is stretched in the magnetosensitive direction, the central portion of the magnetic sensor element 1 parallel to the magnetosensitive direction is compressed in the direction orthogonal to the magnetosensitive direction. Therefore, when the magnetoresistive element portion is disposed in the center portion of the magnetic sensor element 1A, the direction of the stress-induced anisotropy of the magnetic film 13, which is expressed by the inverse magnetostrictive effect, is parallel to the direction of the bias magnetic field as described above. This can suppress variations in resistance of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 due to stress-induced anisotropy.

Fig. 11 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element, the midpoint potential between the first magnetoresistive element and the second magnetoresistive element, the midpoint potential between the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the midpoint potentials before the magnetic sensor element of embodiment 2 is pulled in the magnetic sensing direction.

As shown in fig. 11, before the magnetic sensor element 1A is stretched in the magnetosensitive direction, as described above, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 have the same value, and the resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 have the same value. Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have the same value. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.5. Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, is 0.

Fig. 12 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element, the midpoint potential between the first magnetoresistive element and the second magnetoresistive element, the midpoint potential between the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the two midpoint potentials after the magnetic sensor element of embodiment 2 is stretched in the magnetic sensing direction.

As shown in fig. 12, after the magnetic sensor element 1A of embodiment 2 is stretched in the magnetosensitive direction, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 have different values as described above. The resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 have different values. Therefore, the midpoint potential Vout1 calculated by the above equation (1) has a different value before and after stretching. Similarly, the midpoint potential Vout2 calculated by the above equation (2) has a different value before and after stretching. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.667.

On the other hand, the change in the resistance R1 of the first magnetoresistive element E1 before and after stretching is substantially the same as the change in the resistance R3 of the third magnetoresistive element E3, and the change in the resistance R2 of the second magnetoresistive element E2 before and after stretching is substantially the same as the change in the resistance R4 of the fourth magnetoresistive element E4. Therefore, the value of the midpoint potential Vout1 after stretching is substantially the same as the value of the midpoint potential Vout 2. As a result, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, becomes 0. As a result, in the magnetic sensor according to embodiment 2, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, can be suppressed from changing before and after stretching.

In the magnetic sensor according to embodiment 2, when a tensile stress acts on the substrate 10 in a direction parallel to the magnetosensitive direction, the stress-induced anisotropy of the magnetic film 13 is exhibited in a direction parallel to the direction of the bias magnetic field, and thus the reliability against stress fluctuations can be improved.

(embodiment mode 3)

Fig. 13 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element unit according to embodiment 3, forces acting on the respective magnetoresistive elements when the magnetoresistive elements are stretched, magnetization directions of the respective magnetoresistive elements, and the like. A magnetoresistive element according to embodiment 3 will be described with reference to fig. 13.

As shown in fig. 13, in the magnetic sensor according to embodiment 3, the arrangement pattern of the plurality of magnetoresistive elements constituting the magnetoresistive element portion is different from that of the magnetic sensor 100 according to embodiment 1. The other structures are substantially the same.

The magnetic sensor element 1B includes a first magnetoresistive element E1, a second magnetoresistive element E2, a third magnetoresistive element E3, and a fourth magnetoresistive element E4 arranged in a row. The first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are arranged in parallel with the direction of the bias magnetic field in the order of the third magnetoresistive element E3, the fourth magnetoresistive element E4, the second magnetoresistive element E2, and the first magnetoresistive element E1, and are electrically connected in series in this order.

One end side of the third magnetoresistive element E3 is electrically connected to the electrode pad Vdd through a wiring pattern. The other end side of the third magnetoresistive element E3 is electrically connected to one end side of the fourth magnetoresistive element E4 by a wiring pattern, and is electrically connected to the electrode pad S2.

One end side of the fourth magnetoresistive element E4 is connected to the other end side of the third magnetoresistive element E3 by a wiring pattern, and is electrically connected to the electrode pad S2. The other end side of the fourth magnetoresistive element E4 is electrically connected to one end side of the second magnetoresistive element E2 via a wiring pattern.

One end side of the second magnetoresistive element E2 is electrically connected to the other end side of the fourth magnetoresistive element E4 via a wiring pattern. The other end side of the second magnetoresistive element E2 is electrically connected to one end side of the first magnetoresistive element E1 by a wiring pattern, and is electrically connected to the electrode pad S1.

One end side of the first magnetoresistive element E1 is electrically connected to the other end side of the second magnetoresistive element E2 by a wiring pattern, and is electrically connected to the electrode pad S1. The other end side of the first magnetoresistive element E1 is electrically connected to the electrode pad G.

When a voltage is applied between the electrode pad Vdd and the electrode pad G, the midpoint potential Vout1 and the midpoint potential Vout2 are extracted from the electrode pad S1 and the electrode pad S2 in accordance with the magnetic field strength.

In this case, the midpoint potential Vout1 and the midpoint potential Vout2 are also expressed by the above-described equations (1) and (2) as in embodiment 1.

Fig. 14 is a diagram showing changes in the resistance of the plurality of magnetoresistive elements in the case where the magnetic sensor element of embodiment 3 is stretched in the magnetosensitive direction. In fig. 14, the force acting on the magnetoresistive element before stretching is shown by a broken line, the force acting on the magnetoresistive element after stretching is shown by a solid line, and the resistances of the magnetoresistive elements before and after stretching are shown by numerical values (relative ratios).

As shown in fig. 14, before the magnetic sensor element 1B is stretched in the magnetosensitive direction, the stress distribution in the direction parallel to the magnetosensitive direction (the short-side direction) becomes convex in such a manner that the central portion in the short-side direction becomes larger due to the initial stress. In this case, the first magnetoresistive element E1 and the second magnetoresistive element E2, and the third magnetoresistive element E3 and the fourth magnetoresistive element E4 are located at the center in the short direction. Accordingly, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are substantially equal to each other. In this case, the resistance R1 of the first magnetoresistive element E1, the resistance R2 of the second magnetoresistive element E2, the resistance R3 of the third magnetoresistive element E3, and the resistance R4 of the fourth magnetoresistive element E4 are set to 5.

On the other hand, after the magnetic sensor element 1B is stretched in the magnetic sensing direction, that is, when a tensile stress acts on the substrate 10 in a direction parallel to the magnetic sensing direction, a stress Bstress acts on each magnetoresistive element. Thus, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 change before the magnetic sensor element 1 is stretched in the magnetic sensing direction.

Specifically, the resistance R1 of the first magnetoresistive element E1, the resistance R2 of the second magnetoresistive element E2, the resistance R3 of the third magnetoresistive element E3, and the resistance R4 of the fourth magnetoresistive element E4 change from 5 to 4.

On the other hand, when the magnetic sensor element 1B is stretched in the magnetosensitive direction, the center portion of the magnetic sensor element 1B parallel to the magnetosensitive direction is compressed in the direction orthogonal to the magnetosensitive direction. Therefore, when the magnetoresistive element portion is disposed in the center portion of the magnetic sensor element 1B, the direction of the stress-induced anisotropy of the magnetic film 13, which is expressed by the inverse magnetostrictive effect, is parallel to the direction of the bias magnetic field as described above. This can suppress variations in resistance of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 due to stress-induced anisotropy.

Fig. 15 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element, the midpoint potential between the first magnetoresistive element and the second magnetoresistive element, the midpoint potential between the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the midpoint potentials before the magnetic sensor element of embodiment 3 is pulled in the magnetic sensing direction.

As shown in fig. 15, before the magnetic sensor element 1B is stretched in the magnetosensitive direction, as described above, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 have the same value, and the resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 have the same value. Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have the same value. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.5. As a result, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, becomes 0.

Fig. 16 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element after the magnetic sensor element of embodiment 3 is stretched in the magnetosensitive direction, the midpoint potential between the first magnetoresistive element and the second magnetoresistive element, the midpoint potential between the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the two midpoint potentials.

As shown in fig. 16, after the magnetic sensor element 1B is stretched in the magnetic sensing direction, as described above, the resistance R1 of the first magnetoresistive element E1 and the resistance R2 of the second magnetoresistive element E2 have the same value, and the resistance R3 of the third magnetoresistive element E3 and the resistance R4 of the fourth magnetoresistive element E4 have the same value. Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have the same value. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.5. As a result, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, becomes 0. As a result, in the magnetic sensor according to embodiment 3, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, can be suppressed from changing before and after stretching.

In the magnetic sensor according to embodiment 3, when a tensile stress acts on the substrate 10 in a direction parallel to the magnetosensitive direction, the stress-induced anisotropy of the magnetic film 13 is exhibited in a direction parallel to the direction of the bias magnetic field, and thus the reliability against stress fluctuation can be improved.

In the magnetic sensor according to embodiment 3, the laminated body 11 as the magnetoresistive element unit includes the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4, and the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are arranged in a row in the order of the third magnetoresistive element E3, the fourth magnetoresistive element E4, the second magnetoresistive element E2, and the first magnetoresistive element E1 along the direction parallel to the direction of the bias magnetic field, and are electrically connected in series, and the midpoint potential of the first magnetoresistive element E1 and the second magnetoresistive element E588 is detected from a connection portion connecting the first magnetoresistive element E1 and the second magnetoresistive element E2, and the midpoint potential of the third magnetoresistive element E3 and the fourth magnetoresistive element E4 is detected from a connection portion 3 and the fourth magnetoresistive element E4.

Thus, as described above, before and after stretching, the fluctuation of the midpoint potential Vout1 can be suppressed, and the fluctuation of the midpoint potential Vout2 can also be suppressed.

Comparative example

Fig. 17 is a schematic diagram showing a pattern of a plurality of magnetoresistive elements constituting a magnetoresistive element unit of a comparative example, and forces acting on the respective magnetoresistive elements and magnetization directions of the respective magnetoresistive elements when the magnetic sensor element is stretched.

As shown in fig. 17, the magnetic sensor of the comparative example is different from the magnetic sensor 100 of embodiment 1 mainly in the arrangement pattern of the plurality of magnetoresistive elements constituting the magnetoresistive element section and in that the magnetic film 13 has a positive magnetostriction constant. The other structures are substantially the same.

The magnetic sensor element 1X includes a first magnetoresistive element E1, a second magnetoresistive element E2, a third magnetoresistive element E3, and a fourth magnetoresistive element E4 arranged in a row direction. The first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 are arranged in the order of the third magnetoresistive element E3, the fourth magnetoresistive element E4, the second magnetoresistive element E2, and the first magnetoresistive element E1 along the magnetic sensitive direction orthogonal to the direction of the bias magnetic field.

One end side of the third magnetoresistive element E3 is electrically connected to the electrode pad Vdd through a wiring pattern. The other end side of the third magnetoresistive element E3 is electrically connected to one end side of the fourth magnetoresistive element E4 by a wiring pattern, and is electrically connected to the electrode pad S2.

One end side of the fourth magnetoresistive element E4 is connected to the other end side of the third magnetoresistive element E3 by a wiring pattern, and is electrically connected to the electrode pad S2. The other end side of the fourth magnetoresistive element E4 is electrically connected to one end side of the second magnetoresistive element E2 via a wiring pattern, and is electrically connected to the electrode pad G.

One end side of the second magnetoresistive element E2 is electrically connected to the other end side of the fourth magnetoresistive element E4 via a wiring pattern, and is also electrically connected to the electrode pad G. The other end side of the second magnetoresistive element E2 is electrically connected to one end side of the first magnetoresistive element E1 by a wiring pattern, and is electrically connected to the electrode pad S1.

One end side of the first magnetoresistive element E1 is electrically connected to the other end side of the second magnetoresistive element E2 by a wiring pattern, and is electrically connected to the electrode pad S1. The other end side of the second magnetoresistive element E2 is electrically connected to the electrode pad Vdd.

When a voltage is applied between the electrode pad Vdd and the electrode pad G, the midpoint potential Vout1 and the midpoint potential Vout2 are extracted from the electrode pad S1 and the electrode pad S2 in accordance with the magnetic field strength.

In this case, the midpoint potential Vout1 and the midpoint potential Vout2 are also expressed by the above-described equations (1) and (2) as in embodiment 1.

Fig. 18 is a diagram showing changes in the resistances of the plurality of magnetoresistive elements in the case where the magnetic sensor element of the comparative example is stretched in the magnetosensitive direction. In fig. 18, the force acting on the magnetoresistive element before stretching is shown by a broken line, the force acting on the magnetoresistive element after stretching is shown by a solid line, and the resistances of the magnetoresistive elements before and after stretching are shown by numerical values (relative ratios).

As shown in fig. 18, before the magnetic sensor element 1X is stretched in the magnetosensitive direction, the stress distribution in the direction parallel to the magnetosensitive direction (the short-side direction) becomes convex in such a manner that the central portion in the short-side direction becomes larger due to the initial stress. In this case, the second magnetoresistive element E2 and the fourth magnetoresistive element E4 are located near the center in the lateral direction, and the first magnetoresistive element E1 and the third magnetoresistive element E3 are disposed apart from the center in the lateral direction.

Therefore, the resistance R2 of the second magnetoresistive element E2 and the resistance R4 of the fourth magnetoresistive element E4 are substantially equal to each other. The resistance R1 of the first magnetoresistive element E1 and the resistance R3 of the third magnetoresistive element E3 are substantially equal to each other. In this case, the resistance R2 of the second magnetoresistive element E2 and the resistance R4 of the fourth magnetoresistive element E4 are set to 4, and the resistance R1 of the first magnetoresistive element E1 and the resistance R3 of the third magnetoresistive element E3 are set to 2.

On the other hand, after the magnetic sensor element 1 is stretched in the magnetosensitive direction, that is, when a tensile stress acts on the substrate 10 in a direction parallel to the magnetosensitive direction, a stress Bstress acts on each magnetoresistive element, and stress-induced anisotropy of the magnetic film 13 is expressed in a direction parallel to the magnetosensitive direction. Accordingly, the resistances of the first magnetoresistive element E1, the second magnetoresistive element E2, the third magnetoresistive element E3, and the fourth magnetoresistive element E4 change greatly from before the magnetic sensor element 1 is stretched in the magnetic sensing direction.

Specifically, the resistance R1 of the first magnetoresistive element E1 changes from 3 to 2. The resistance R2 of the second magnetoresistive element E2 changes from 4 to 5. The resistance R3 of the third magnetoresistive element E3 changes from 2 to 1. The resistance R4 of the fourth magnetoresistive element E4 changes from 4 to 3.

Fig. 19 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element, the midpoint potential between the first magnetoresistive element and the second magnetoresistive element, the midpoint potential between the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the midpoint potentials before the magnetic sensor element of the comparative example is stretched in the magnetic sensing direction.

As shown in fig. 19, before the magnetic sensor element 1X is pulled, as described above, the resistance R1 of the first magnetoresistive element E1 and the resistance R3 of the third magnetoresistive element E3 have the same value, and the resistance R2 of the second magnetoresistive element E2 and the resistance R4 of the fourth magnetoresistive element E4 have the same value. Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have the same value. Specifically, the midpoint potential Vout1 and the midpoint potential Vout2 are 0.667. As a result, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, becomes 0.

Fig. 20 is a diagram showing a force acting from the first magnetoresistive element to each magnetoresistive element of the fourth magnetoresistive element after the magnetic sensor element of the comparative example is stretched in the magnetosensitive direction, the midpoint potential of the first magnetoresistive element and the second magnetoresistive element, the midpoint potential of the third magnetoresistive element and the fourth magnetoresistive element, and the difference between the midpoint potentials.

As shown in fig. 20, after the magnetic sensor element 1X is stretched in the magnetosensitive direction, the resistance R1 of the first magnetoresistive element E1 and the resistance R4 of the fourth magnetoresistive element E4 are the same value, but the resistance R2 of the second magnetoresistive element E2 and the resistance R4 of the fourth magnetoresistive element E4 are different values.

Therefore, the midpoint potential Vout1 and the midpoint potential Vout2 calculated from the above equations (1) and (2) have different values from each other. Specifically, the midpoint potential Vout1 is 0.625, and the midpoint potential Vout2 is 0.75. Thus, Voff, which is the difference between the midpoint potential Vout1 and the midpoint potential Vout2, is-0.125.

As described above, in the magnetic sensor of the comparative example, since the stress-induced anisotropy of the magnetic film 13 is exhibited in the direction parallel to the magnetosensitive direction, not only the midpoint potential Vout1 and the midpoint potential Vout2 but also Voff fluctuates before and after the stretching. As a result, the magnetic sensor of the comparative example has a reduced reliability against stress fluctuations.

(modification example)

Fig. 21 is a diagram showing forces acting when the magnetic sensor element of the modification is compressed in the magnetism sensing direction. A magnetic sensor according to a modification will be described with reference to fig. 21.

As shown in fig. 21, in the magnetic sensor according to the modification, the magnetic film 13 of the magnetic sensor element 1 is different from the magnetic sensor 100 according to embodiment 1. The other structures are substantially the same.

In the modification, the magnetic film 13 has a positive magnetostriction constant. The magnetic film 13 is formed so that the magnetostriction constant lambda becomes-1 ppm < lambda < 0 ppm. In the modification, when a compressive stress acts on the substrate 10 in a direction parallel to the magnetosensitive direction, the stress-induced anisotropy of the magnetic film is exhibited in a direction parallel to the direction of the bias magnetic field.

Even in the case of such a configuration, the magnetic sensor according to the modification provides substantially the same effects as the magnetic sensor according to embodiment 1.

In the modification, the case where the pattern of the plurality of magnetoresistive elements in the stacked body as the magnetoresistive element portion is the same as that of embodiment 1 is described as an example, but the present invention is not limited thereto, and the pattern may be the same as that of embodiment 2 or embodiment 3.

(other modification example)

In embodiments 1 to 3 and the modifications, the case where the first magnetoresistive element E1 to the fourth magnetoresistive element E4 have a linear shape was described as an example, but the present invention is not limited to this, and a meandering shape may be formed by alternately connecting a long short stripe pattern and a short stripe pattern in an orthogonal manner.

In embodiments 1 to 3 and the modification, the case where one wheatstone bridge circuit including four resistance regions is formed in the magnetic sensor element 1 has been described as an example, but the present invention is not limited thereto. For example, the magnetoresistive element portion may be formed by only one resistor without forming a bridge circuit in the magnetic sensor 1, or a plurality of bridge circuits may be formed in one magnetic sensor element 1.

(embodiment mode 4)

(Current sensor)

Fig. 22 is a perspective view of a current sensor according to embodiment 4. Fig. 23 is a plan view of a current sensor according to embodiment 4. Fig. 24 is a front view of a current sensor according to embodiment 4.

As shown in fig. 22 to 24, the current sensor 200 includes a support substrate 150 and two magnetic sensors 100. The current sensor 200 detects a current flowing through the object based on magnetic detection by the magnetic sensor 100.

The two magnetic sensors 100 have substantially the same configuration as the magnetic sensor 100 of embodiment 1.

The support substrate 150 is formed of, for example, an integrated chip. Two magnetic sensors 100 are mounted on the support substrate 150. The support substrate 150 is provided with a circuit (not shown) for performing predetermined signal processing (differential amplification or the like) on the signals output from the two magnetic sensors 100.

The current sensor 200 is arranged such that one end side in the left-right direction in fig. 24 is located above the bus bar 210, and the other end side in the left-right direction in fig. 24 is located below the bus bar 220. The current sensor 200 is shown by a two-dot chain line shown in fig. 24, and is arranged in a stepped space S formed between the bus bar 210 and the bus bar 220.

The current to be measured flows through the bus bars 210 and 220. The bus bars 210 and 220 are arranged in line when viewed from the normal direction thereof. The bus bars 210 and 220 are arranged offset in the vertical direction. The bus bars 210 and 220 are configured by, for example, rod-shaped conductor branches for power supply connected to the in-vehicle battery.

The current sensor 200 detects magnetism (magnetic field) applied from the bus bars 210 and 220 by the two magnetic sensors 100. In this case, the direction of the bias magnetic field applied from the magnet (not shown) to the magnetoresistive element is the front-rear direction in fig. 24. The magnetic detection direction (magnetosensitive direction) of the current sensor 200 is the left-right direction in fig. 24.

When the bus bar 210 is positioned on the back side of the support substrate 150 and the bus bar 220 is positioned on the front side of the support substrate 150, magnetic vectors (see the one-dot chain line arrows in fig. 24) in directions parallel to the surface of the support substrate 150 (the left and right directions in fig. 24) and different (opposite) directions are given to the two magnetic sensors 100 when a current flows through the bus bars 210 and 220 in the directions of the arrows shown in fig. 23.

By detecting the magnetic vectors as voltage values (hall voltages) by the two magnetic sensors 100, it is possible to detect (differentially detect) currents flowing through the bus bars 210 and 220 based on the differential amplification values of the magnetic vectors (voltage values) detected.

By taking the difference value (subtraction) of the magnetic vectors in this manner, the influence of external disturbance (external disturbance magnetic field) is cancelled (canceled) and removed, and only the signal component corresponding to the magnetism (magnetic field) caused by the current flowing through the subject (bus bar) is extracted and detected.

The current sensor 200 according to embodiment 4 includes the two magnetic sensors 100 according to embodiment 1, and thereby substantially the same effects as those of embodiment 1 are obtained.

In embodiment 4, a case where the current sensor 200 includes the magnetic sensor 100 of embodiment 1 is described as an example, but the present invention is not limited to this. The current sensor 200 may include any of the magnetic sensors according to embodiments 2 and 3, and the modifications and other modifications.

The embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Description of reference numerals:

1. 1A, 1X magnetic sensor element, 2 lead frame, 3 bonding member, 4 bonding wire, 5 molding member, 10 substrate, 11 laminate, 12 base film, 13 magnetic film, 14 protective film, 15 electrode portion, 16 protective layer, 16a contact hole, 100 magnetic sensor, 150 support substrate, 200 current sensor, 210, 220 bus bar, E1 first magnetoresistive element, E2 second magnetoresistive element, E3 third magnetoresistive element, Ed fourth magnetoresistive element.