WO2015125699A1 - Capteur magnétique - Google Patents

Capteur magnétique Download PDF

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Publication number
WO2015125699A1
WO2015125699A1 PCT/JP2015/053922 JP2015053922W WO2015125699A1 WO 2015125699 A1 WO2015125699 A1 WO 2015125699A1 JP 2015053922 W JP2015053922 W JP 2015053922W WO 2015125699 A1 WO2015125699 A1 WO 2015125699A1
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Prior art keywords
magnetic field
magnetoresistive effect
bridge circuit
coil
magnetic
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PCT/JP2015/053922
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English (en)
Japanese (ja)
Inventor
高橋　彰
井出　洋介
斎藤　正路
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アルプス電気株式会社
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Priority claimed from JP2014137093A external-priority patent/JP2017072375A/ja
Application filed by アルプス電気株式会社 filed Critical アルプス電気株式会社
Publication of WO2015125699A1 publication Critical patent/WO2015125699A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates

Definitions

  • the present invention relates to a magnetic sensor having a magnetoresistive effect element, and more particularly to a magnetic sensor in which a bias magnetic field is applied to a free magnetic layer.
  • Patent Document 1 discloses a current sensor that detects a magnetic field generated from a current to be measured by a magnetic sensor and measures the magnitude of the current to be measured.
  • a magnetoresistive effect element such as a GMR element is used.
  • FIG. 13 is a plan view of a conventional magnetic sensor described in Patent Document 1.
  • the conventional magnetic sensor 101 includes a plurality of magnetoresistive elements 121a to 121d.
  • a pair of magnetoresistive effect elements 121a and 121b formed on the sensor chip 102a constitutes a half bridge circuit
  • a pair of magnetoresistive effect elements 121c and 121d formed on the sensor chip 102b constitutes a half bridge circuit.
  • a full bridge circuit 125 is constituted by two half bridge circuits.
  • Each of the magnetoresistive effect elements 121a to 121d has a free magnetic layer whose magnetization direction is changed by an external magnetic field and a fixed magnetic layer whose magnetization direction is fixed.
  • the magnetization direction 133 of the free magnetic layer changes, and thereby the electric resistance values of the magnetoresistive effect elements 121a to 121d vary.
  • the magnetic sensor 101 can detect an external magnetic field based on the electric resistance values of the magnetoresistive effect elements 121a to 121d.
  • a hard bias layer 122 is provided across the magnetoresistive elements 121a to 121d, and a bias magnetic field 132 generated from the hard bias layer 122 is applied to the free magnetic layer.
  • the magnetization direction 133 of the free magnetic layer is directed in the direction of the bias magnetic field 132 when the external magnetic field becomes no magnetic field.
  • the magnetization direction 133 of the free magnetic layer can be controlled in a predetermined direction, and an external magnetic field can be detected with good reproducibility.
  • the magnetization directions 131 of the pinned magnetic layers are directed in opposite directions, and the magnetization directions 133 of the free magnetic layers are directed in opposite directions. ing.
  • the sensitivities of the magnetoresistive effect elements 121a and 121b change in opposite directions. Deterioration can be suppressed.
  • the bias magnetic field 132 is directed in the magnetization direction of the hard bias layer 122. Therefore, when a strong external magnetic field is applied in a direction different from the magnetization direction of the hard bias layer 122, the magnetization direction of the hard bias layer 122 may be shifted, and the direction of the bias magnetic field 132 may be shifted.
  • the direction of the bias magnetic field 132 does not return even when the external magnetic field becomes no magnetic field.
  • the magnetization direction 133 of the layer is also shifted. If the magnetization direction 133 of the free magnetic layer is deviated, the characteristics of the magnetic sensor 101 are degraded, such as a change in sensitivity of the magnetic sensor 101 and the occurrence of an offset. Further, the change in the magnetization direction of the hard bias layer 122 is an irreversible change, and once the magnetization direction of the hard bias layer 122 changes, it is difficult to recover the characteristics of the magnetoresistive elements 121a to 121d. Challenges arise.
  • the present invention solves the above-described problem, suppresses a decrease in linearity of the sensor output due to a deviation in the direction of the magnetic field to be measured, and prevents a change in the direction of the bias magnetic field due to an external magnetic field, thereby free layer
  • An object of the present invention is to provide a magnetic sensor capable of controlling the magnetization direction of the magnetic field.
  • the magnetic sensor of the present invention includes a pair of magnetoresistive effect elements formed on a substrate, and a coil provided on the pair of magnetoresistive effect elements via an insulating layer.
  • Each magnetoresistive effect element includes a fixed magnetic layer whose magnetization direction is fixed and a free magnetic layer whose magnetization direction is changed by an external magnetic field, and the pair of magnetoresistive effect elements constitutes a half-bridge circuit.
  • the magnetization directions of the pinned magnetic layers of the pair of magnetoresistive elements are opposite to each other, and the magnetization directions of the free magnetic layers are opposite to each other.
  • the free magnetic layer intersects with the extending direction.
  • the magnetization direction of the free magnetic layer of the pair of magnetoresistive effect elements is directed in the opposite direction. Therefore, even when the magnetic field to be measured is applied with an inclination to the bias magnetic field, the bias magnetic field acts in the positive direction with respect to the magnetic field to be measured in the free magnetic layer of one magnetoresistive element, and the other magnetic field. In the free magnetic layer of the resistance effect element, a bias magnetic field acts in the minus direction with respect to the magnetic field to be measured. Accordingly, since the sensitivity of the pair of magnetoresistive elements changes in opposite directions, the change in sensitivity of the pair of magnetoresistive elements is canceled out, and the decrease in linearity of the sensor output is suppressed.
  • a bias magnetic field can be generated by passing a current through the coil, and even when a strong magnetic field is applied from the outside, it is possible to suppress the irreversible change in the direction of the bias magnetic field. Therefore, when the external magnetic field is no magnetic field, the magnetization direction of the free magnetic layer can be controlled to be constant to the direction of the bias magnetic field. Furthermore, in contrast to the configuration in which the direction of the bias magnetic field is determined by magnetizing the hard bias layer provided in each magnetoresistive effect element, the direction of the bias magnetic field can be easily controlled by the shape of the coil and the direction of the current flowing through the coil.
  • the bias magnetic field can be applied to the free magnetic layers of the pair of magnetoresistive elements in opposite directions.
  • the magnetic sensor of the present invention it is possible to prevent a change in the direction of the bias magnetic field due to an external magnetic field while suppressing a decrease in linearity of the sensor output due to a deviation in the direction of the magnetic field to be measured. It is possible to control the magnetization direction.
  • the coil is a planar coil wound on the insulating layer, and the pair of magnetoresistive elements are provided at positions overlapping the coil with a planar center of the coil interposed therebetween. . According to this, since the currents flowing through the coils on the pair of magnetoresistive elements flow in opposite directions, the bias magnetic field generated by the coils is opposite to the free magnetic layer of the pair of magnetoresistive elements. Acts on direction. Therefore, the magnetization direction of the free magnetic layer can be reliably directed in the opposite direction by one coil.
  • the magnetoresistive effect element has a plurality of element portions extending in a band shape, the plurality of element portions are connected in a meander shape, and the magnetization direction of the free magnetic layer is in the extending direction of the element portion. It is preferable that the wiring constituting the coil is provided so as to intersect with the extending direction of the element portion in plan view. According to this, the magnetization direction of the free magnetic layer is directed to the extending direction of the element portion due to the shape anisotropy of the element portion, and the magnetization direction of the free magnetic layer is shifted by applying a strong magnetic field in a different direction. Even in this case, a bias magnetic field can be applied in the extending direction of the element portion to prevent the magnetization direction of the free magnetic layer from shifting.
  • a full bridge circuit having a first half bridge circuit and a second half bridge circuit is formed on the substrate. According to this, since the decrease in the linearity of the sensor output is suppressed in each of the two half-bridge circuits, the decrease in the linearity of the sensor output is also suppressed in the full-bridge circuit having the two half-bridge circuits. In addition, a bias magnetic field can be applied to each magnetoresistive element constituting the full bridge circuit by one coil, and the magnetization direction of the free magnetic layer can be easily controlled.
  • the one magnetoresistive effect element constituting the first half bridge circuit and the one magnetoresistive effect element constituting the second half bridge circuit have the same magnetization direction of the free magnetic layer. Preferably it is directed. According to this, the output fluctuation of the first half-bridge circuit and the output fluctuation of the second half-bridge circuit are canceled out by the full-bridge circuit, and the decrease in linearity of the sensor output can be reliably suppressed. .
  • a virtual line connecting the pair of magnetoresistive elements constituting the first half bridge circuit and a virtual line connecting the pair of magnetoresistive elements forming the second half bridge circuit It is preferable that the full bridge circuit is formed so as to intersect. According to this, when the variation of the magnetic field to be measured for each magnetoresistive element occurs, the error of the resistance value of each magnetoresistive element is absorbed by the full bridge circuit, and the error of the sensor output can be reduced. it can.
  • the decrease in linearity of the sensor output due to the deviation of the direction of the magnetic field to be measured is suppressed, and the change in the direction of the bias magnetic field due to the external magnetic field is prevented, so that the magnetization of the free magnetic layer It is possible to control the direction.
  • FIG. 3 is a cross-sectional view of the magnetic sensor as viewed from the direction of the arrow cut along the line III-III in FIGS. 1 and 2. It is a circuit diagram of the full bridge circuit comprised from four magnetoresistive effect elements. It is a top view of a magnetoresistive effect element.
  • FIG. 6 is a partial enlarged cross-sectional view of the magnetoresistive effect element as viewed from the direction of the arrow cut along line VI-VI in FIG. 5.
  • FIG. 1 is a plan view of the magnetic sensor according to the first embodiment.
  • FIG. 2 is a plan view of the magnetic sensor in a state where the coil of FIG. 1 is removed, and is a plan view showing the configuration of each magnetoresistive element.
  • FIG. 3 is a cross-sectional view of the magnetic sensor taken along the line III-III in FIGS. 1 and 2 and viewed from the direction of the arrows.
  • FIG. 4 is a circuit diagram of a full bridge circuit composed of four magnetoresistive elements.
  • the magnetic sensor of the present embodiment can be used for a magnetic proportional current sensor, for example, and is disposed in the vicinity of the current line to detect a measured magnetic field generated by a current flowing through the current line and measure a current value. can do.
  • the magnetic sensor 10 of this embodiment includes four magnetoresistive elements 21a to 21d formed on a substrate 15. Further, as shown in FIGS. 1 and 3, a coil 27 is provided on the magnetoresistive effect elements 21a to 21d with an insulating layer 16 interposed therebetween. A protective layer 17 is provided so as to cover the coil 27.
  • the magnetoresistive effect element 21a and the magnetoresistive effect element 21b, and the magnetoresistive effect element 21c and the magnetoresistive effect element 21d are located diagonally to each other and connected by wirings 22.
  • each of the magnetoresistive effect elements 21 a to 21 d is electrically connected to the connection terminal 23.
  • the magnetoresistive effect element 21a and the magnetoresistive effect element 21b connected together constitute a first half-bridge circuit 51, and the magnetoresistive effect element 21c and the magnetoresistive effect element 21d form the second half bridge circuit 51.
  • a half-bridge circuit 52 is configured. As shown in FIG. 4, a first half-bridge circuit 51 and a second half-bridge circuit 52 are connected in parallel between an input terminal (Vdd) and a ground terminal (GND), so that a full-bridge circuit is obtained. 53.
  • FIG. 5 is a plan view of the magnetoresistive effect element.
  • FIG. 5 shows the configuration of the magnetoresistive effect element 21a, but the other magnetoresistive effect elements 21b to 21d have the same configuration.
  • the magnetoresistive effect element 21a includes a plurality of element portions 31 extending in a strip shape in the X1-X2 direction.
  • the plurality of element portions 31 are arranged at intervals in the Y1-Y2 direction, and the plurality of element portions 31 are connected to each other in a meander shape by a connecting portion 32.
  • each element portion 31 of the magnetoresistive effect element 21a uses a GMR (Giant Magneto Resistance) element, and a free magnetic field whose magnetization direction is changed by an external magnetic field and a fixed magnetic layer whose magnetization direction is fixed.
  • GMR Gate Magneto Resistance
  • a magnetic layer In FIG. 5, the pinned magnetic layer and the free magnetic layer are not shown, and the magnetization direction 45a of the pinned magnetic layer and the magnetization direction 47a of the free magnetic layer are indicated by arrows.
  • the magnetization direction 45 a of the pinned magnetic layer is oriented in a direction orthogonal to the extending direction of the element portion 31, and the magnetization direction 47 a of the free magnetic layer is anisotropic in shape of the element portion 31. Depending on the nature, it is directed in the extending direction of the element portion 31.
  • the magnetization direction 45a of the fixed magnetic layer and the magnetization direction 47a of the free magnetic layer are directed in the in-plane direction of the magnetoresistive effect element 21a, and are directed in directions orthogonal to each other when no external magnetic field is applied.
  • the magnetization directions 45a of the pinned magnetic layers of the magnetoresistive effect element 21a and the magnetoresistive effect element 21b constituting the first half bridge circuit 51 are directed in opposite directions. .
  • the magnetization directions 47a of the free magnetic layers of the magnetoresistive effect element 21a and the magnetoresistive effect element 21b are also directed in opposite directions.
  • the magnetoresistive effect element 21c and the magnetoresistive effect element 21d constituting the second half bridge circuit 52 are also configured with the same magnetization direction.
  • the magnetoresistive effect elements 21a and 21c the magnetization direction of the fixed layer and the magnetization direction of the free magnetic layer are opposite to each other.
  • the magnetoresistive effect elements 21b and 21d the magnetization direction of the fixed layer and the magnetization direction of the free magnetic layer are opposite to each other.
  • the angle between the magnetization direction 47a of the free magnetic layer and the magnetization direction 45a of the pinned magnetic layer is defined as ⁇ .
  • ⁇ the angle between the magnetization direction 47a of the free magnetic layer and the magnetization direction 45a of the pinned magnetic layer.
  • the magnetization direction 47a of the free magnetic layer of the magnetoresistive effect element 21a changes in the Y1 direction and the electrical resistance value increases, thereby increasing the magnetoresistive effect element.
  • the magnetization direction 47a of the free magnetic layer 21b changes in the Y1 direction and the electric resistance value decreases.
  • the midpoint potential (V 1 ) of the first half bridge circuit 51 shown in FIG. 4 decreases.
  • the midpoint potential (V 2 ) of the second half bridge circuit 52 increases.
  • the magnetic field to be measured can be detected from this difference (V 1 ⁇ V 2 ).
  • a coil 27 is provided on each of the magnetoresistive effect elements 21a to 21d.
  • the coil 27 is a planar coil in which a coil wiring 27 a is wound on the insulating layer 16.
  • the coil 27 forms a spiral coil in which a coil wire 27a is continuously wound in an oval shape, and includes a plurality of straight portions 27b extending in the Y1-Y2 direction, a plurality of straight portions 27c, It has the curved parts 27d and 27e which connect the parts 27b and 27c.
  • terminal portions 28a and 28b are connected to the coil wiring 27a.
  • an opening is formed in a part of the protective layer 17 covering the coil 27, and the terminal portions 28a and 28b are provided exposed from the protective layer 17 in the opening.
  • a power source (not shown) is connected to the terminal portions 28a and 28b, a current is passed through the coil 27, and currents are passed through the straight portion 27b and the straight portion 27c in opposite directions.
  • a pair of magnetoresistive elements 21a and 21b are provided at positions overlapping the coil 27 with the plane center O of the coil 27 interposed therebetween.
  • one magnetoresistive element 21 a constituting the first half-bridge circuit 51 is disposed at a position overlapping the linear portion 27 b of the coil 27, and the other constituting the first half-bridge circuit 51.
  • the magnetoresistive effect element 21b is disposed at a position overlapping the linear portion 27c.
  • the element portions 31 (not shown in FIG. 3) of the magnetoresistive effect element 21a and the magnetoresistive effect element 21b extend in the X1-X2 direction, and the coil wiring 27a constituting the coil 27 is free of the element portion 31. They are arranged so as to intersect with the extending direction of the magnetic layer in plan view.
  • a bias magnetic field 29 is generated by passing a current through the coil 27, and the bias magnetic field 29 generated in the linear portion 27b is applied to the magnetoresistive effect element 21a.
  • the bias magnetic field 29 generated in the linear portion 27c is applied to the magnetoresistive effect element 21b.
  • the magnetization direction 47a of the free magnetic layer is directed to the direction of the bias magnetic field 29. As shown in FIG. 3, the magnetization direction 47a of the free magnetic layer of the magnetoresistive effect element 21a is in the X2 direction, and the free direction of the magnetoresistive effect element 21b.
  • the magnetization direction 47a of the magnetic layer is directed in the opposite direction to the X1 direction.
  • a bias magnetic field 29 is generated by passing a current through the coil 27, a strong magnetic field is applied from the outside in a direction different from the bias magnetic field 29, and the magnetocrystalline anisotropy of the free magnetic layer. Even when a shift occurs in the direction of the magnetic field, the direction of magnetocrystalline anisotropy can be redirected to the direction of the bias magnetic field 29.
  • the magnetocrystalline anisotropy refers to the magnetic anisotropy of the magnetic material itself regardless of the shape. Both the shape magnetic anisotropy and the magnetocrystalline anisotropy act on the free magnetic layer. Therefore, when the external magnetic field is no magnetic field, the magnetization direction 47a of the free magnetic layer can be controlled to be constant in the direction of the bias magnetic field 29.
  • the bias magnetic field 29 is determined by the shape of the coil 27 and the direction of the current flowing through the coil 27. The direction can be controlled. Therefore, it is easy to cause the bias magnetic field 29 to act on the pair of magnetoresistive elements 21 a and 21 b provided on one substrate 15 in different directions, and the magnetization direction of the free magnetic layer by the bias magnetic field 29. 47a can be directed in opposite directions.
  • the bias magnetic field 29 can be generated by always passing a current through the coil 27.
  • the magnetization direction 47a of the free magnetic layer is kept constant in the direction of the bias magnetic field 29. be able to.
  • the method of applying the bias magnetic field 29 is not limited to this, and a current is passed through the coil 27 at regular intervals to generate the bias magnetic field 29 to periodically correct the magnetization direction 47a of the free magnetic layer.
  • a method of generating a bias magnetic field 29 when a deviation in the magnetization direction 47a of the free magnetic layer is detected and resetting the magnetization direction 47a of the free magnetic layer may be used.
  • FIG. 3 shows the pair of magnetoresistive elements 21a and 21b constituting the first half-bridge circuit 51, the pair of magnetoresistive elements 21c constituting the second half-bridge circuit 52. , 21d, the bias magnetic field 29 is similarly applied.
  • the magnetoresistive effect element 21c is disposed at a position overlapping the straight line portion 27c
  • the magnetoresistive effect element 21d is disposed at a position overlapping the straight line portion 27b. Therefore, the bias magnetic field 29 acts on the magnetoresistive effect element 21c and the magnetoresistive effect element 21d in opposite directions.
  • FIG. 1 shows the magnetoresistive effect element 21c and the magnetoresistive effect element 21d in opposite directions.
  • the magnetization direction 47a of the free magnetic layer of the magnetoresistive effect element 21c is oriented in the X1 direction
  • the magnetization direction 47a of the free magnetic layer of the magnetoresistive effect element 21d is oriented in the X2 direction, opposite to each other.
  • one coil 27 biases one magnetoresistive effect element 21 a constituting the first half-bridge circuit 51 and one magnetoresistive effect element 21 d constituting the second half-bridge circuit 52.
  • the magnetic field 29 is applied, and the magnetization direction 47a of the free magnetic layer is directed in the same direction.
  • a pair of magnetoresistive elements 21 a and 21 b constituting the first half-bridge circuit 51 are connected by a virtual line 24, and a pair of magnetoresistives constituting the second half-bridge circuit 52.
  • the effect elements 21 c and 21 d are connected by a virtual line 25.
  • the full bridge circuit 53 is configured by arranging the magnetoresistive elements 21a to 21d so that the virtual line 24 and the virtual line 25 intersect each other.
  • FIG. 6 is a partial enlarged cross-sectional view of the magnetoresistive element when viewed from the direction of the arrow cut along the line VI-VI in FIG.
  • FIG. 6 shows the configuration of the magnetoresistive effect element 21a, but the other magnetoresistive effect elements 21b to 21d have the same configuration.
  • the magnetoresistive effect element 21a includes a magnetoresistive effect film 43 that can detect a magnetic field to be measured applied in the film surface.
  • the magnetoresistive film 43 is formed on the upper surface of the silicon substrate 41 with the insulating film 42 and the seed layer 49 interposed therebetween.
  • the magnetoresistive film 43 is laminated in the order of the pinned magnetic layer 45, the nonmagnetic layer 46, and the free magnetic layer 47, and the surface of the free magnetic layer 47 is covered with the protective film 48. It is configured.
  • the pinned magnetic layer 45 has a so-called self-pinned laminated structure including the first ferromagnetic layer 45c / nonmagnetic coupling layer 45e / second ferromagnetic layer 45d.
  • the first ferromagnetic layer 45 c is in direct contact with the seed layer 49.
  • the second ferromagnetic layer 45 d is in direct contact with the nonmagnetic layer 46.
  • the magnetizations of the first ferromagnetic layer 45c and the second ferromagnetic layer 45d are directed in directions different by 180 ° due to indirect exchange interaction (RKKY interaction) due to conductive electrons.
  • the magnetization direction of the second ferromagnetic layer 45d is the magnetization direction of the pinned magnetic layer shown in FIGS.
  • the reason why it contributes to the magnetoresistive effect is the relationship between the relative magnetization directions of the free magnetic layer 47 and the second ferromagnetic layer 45d sandwiching the nonmagnetic layer 46 of FIG.
  • the insulating film 42 may be a silicon oxide film obtained by thermally oxidizing the silicon substrate 41, an alumina film formed by sputtering or the like, an oxide film, or the like.
  • the first ferromagnetic layer 45c and the second ferromagnetic layer 45d of the pinned magnetic layer 45 are made of a soft magnetic material such as a Co—Fe alloy (cobalt-iron alloy).
  • the nonmagnetic coupling layer 45e uses conductive Ru or the like.
  • the nonmagnetic layer 46 is made of Cu (copper) or the like.
  • the free magnetic layer 47 is made of a soft magnetic material such as a Ni—Fe alloy (nickel-iron alloy) having a small coercive force and a high magnetic permeability.
  • the protective film 48 is Ta (tantalum) or the like.
  • the magnetization direction 45a of the pinned magnetic layer 45 is fixed in the Y1 direction or the Y2 direction in a state parallel to the silicon substrate 41, and the magnetization direction 45a of the pinned magnetic layer 45 is set by applying an external magnetic field. Does not fluctuate. Further, the magnetization direction 47a of the free magnetic layer 47 changes depending on the magnetic field applied from the outside. In the state where no external magnetic field is applied, the magnetization direction 47a of the free magnetic layer 47 is directed in the X1-X2 direction due to the shape anisotropy of the element portion 31, and the magnetization direction 45a of the fixed magnetic layer 45 and the magnetization of the free magnetic layer 47 It is orthogonal to the direction 47a.
  • each of the magnetoresistive effect elements 21a to 21d has a so-called self-pin type laminated structure, it is easy to form the magnetoresistive effect elements 21a to 21d on the same substrate 15. This is because the magnetization direction is aligned with the magnetic field direction when the first magnetic layer (or the second magnetic layer) is formed.
  • the second magnetic layer (or the first magnetic layer), which is another magnetic layer, faces in the opposite direction to the first magnetic layer. This is because RKKY-like interaction works between the first and second magnetic layers.
  • the magnetoresistive effect elements 21a to 21d are formed separately for a plurality of sensor chips, it is possible to prevent the sensor chip from being attached and the fixed magnetism between the magnetoresistive effect elements 21a to 21d. Variations in the magnetization direction 45a of the layer 45 and variations in the magnetization direction 47a of the free magnetic layer 47 can be suppressed. Further, since the full bridge circuit 53 having the first half bridge circuit 51 and the second half bridge circuit 52 shown in FIG. 4 is formed on the same substrate 15, the manufacturing process is simplified.
  • One coil 27 is provided at a position overlapping all of the magnetoresistive effect elements 21a to 21d formed on the same substrate 15, and the coil wiring 27a constituting the coil 27 is free of the magnetoresistive effect elements 21a to 21d. It intersects with the extending direction of the magnetic layer 47.
  • the strength and direction of each bias magnetic field 29 applied to the magnetoresistive effect elements 21a to 21d is compared with a case where a hard bias layer is provided on each of the magnetoresistive effect elements 21a to 21d and the bias magnetic field 29 is applied. Variation in the magnetization direction 47a of the free magnetic layer 47 between the magnetoresistive effect elements 21a to 21d can be suppressed.
  • FIG. 7 shows a detection method when the magnetic field to be measured acts on the magnetic sensor of the present embodiment
  • FIG. 7A shows the magnetic field acting on the first magnetoresistive element of the present embodiment
  • FIG. 7B is a schematic plan view for explaining the magnetic field acting on the second magnetoresistance effect element of the present embodiment
  • FIG. 7C is a schematic plan view for explaining the magnetic field acting on the first magnetoresistive element in the magnetic sensor of the comparative example
  • FIG. 7D is the magnetic sensor of the comparative example. It is a schematic plan view for demonstrating the magnetic field which acts on a 2nd magnetoresistive effect element.
  • FIG. 7A to 7D show a case where the external magnetic field 30 to be measured is applied with an inclination with respect to the magnetization direction 45a of the pinned magnetic layer 45.
  • FIG. The magnetic sensor of the comparative example is different in that the magnetization directions (not shown in FIG. 7) of the free magnetic layers of the magnetoresistive effect element 221a and the magnetoresistive effect element 221b are directed in the same direction.
  • a bias magnetic field 229 is applied to the magnetoresistive element 221a and the magnetoresistive element 221b in the same direction.
  • the magnetic field 230 to be measured is applied with an inclination, and the bias magnetic field 229 includes a first component 229a of a bias magnetic field parallel to the magnetic field 230 to be measured.
  • the first component 229a of the bias magnetic field acts in the positive direction with respect to the bias magnetic field 229.
  • both the magnetoresistive effect element 221a and the magnetoresistive effect element 221b have reduced sensitivity.
  • the magnetic field 230 to be measured is reversed 180 °
  • the first component 229a of the bias magnetic field acts in the minus direction with respect to the bias magnetic field 229.
  • the sensitivity of both the magnetoresistive effect element 221a and the magnetoresistive effect element 221b increases. Therefore, when the magnetoresistive effect elements 221a and 221b are configured in the same manner as the first half bridge circuit 51 shown in FIG. Change, linearity deteriorates and measurement error increases.
  • the magnetization direction 45a of the pinned magnetic layer 45 is directed in the reverse direction and the magnetization direction 47a of the free magnetic layer 47 is directed in the reverse direction. Therefore, the bias magnetic field 29 is applied to the magnetoresistive effect element 21a and the magnetoresistive effect element 21b in opposite directions. As shown in FIG. 7A, in the magnetoresistive effect element 21a, the first component 29a of the bias magnetic field acts in the plus direction with respect to the bias magnetic field 29, so that the sensitivity of the magnetoresistive effect element 21a decreases. Further, as shown in FIG.
  • the first component 29a of the bias magnetic field acts in the negative direction with respect to the bias magnetic field 29, so that the sensitivity of the magnetoresistive effect element 21b increases. . Therefore, in the first half-bridge circuit 51 shown in FIG. 4, the sensitivity of the magnetoresistive effect element 21a decreases and the sensitivity of the magnetoresistive effect element 21b increases. Therefore, the first half bridge circuit 51 cancels out the change in output sensitivity of the magnetoresistive effect elements 21a and 21b, and suppresses the decrease in linearity of the sensor output. Even when the measured magnetic field 30 is reversed 180 °, the change in the output sensitivity of the magnetoresistive elements 21a and 21b is canceled out, and the decrease in the linearity of the sensor output is suppressed.
  • FIG. 7 shows the magnetoresistive effect elements 21a and 21b constituting the first half bridge circuit 51
  • the full bridge circuit 53 having the first half bridge circuit 51 and the second half bridge circuit 52 is Even when it is formed on the substrate 15, the same effect is obtained. Since the decrease in the linearity of the sensor output is suppressed in each of the two half bridge circuits 51 and 52, the decrease in the linearity of the sensor output is also suppressed in the full bridge circuit 53 having the two half bridge circuits 51 and 52.
  • FIG. 8A is a graph showing the relationship between the gradient of the measured magnetic field in the magnetic sensor of the example and the linearity of the sensor output
  • FIG. 8B shows the gradient of the measured magnetic field in the magnetic sensor of the comparative example. It is a graph which shows the relationship with the linearity of a sensor output.
  • FIG. 9 is a schematic graph for explaining the linearity of the sensor output.
  • the magnetic sensor of the example has the same configuration as the magnetic sensor 10 shown in the first embodiment, and the magnetic sensor of the comparative example includes a magnetoresistive effect element 221a and a magnetoresistive effect element 221b (not shown in FIG. 10). The configuration in which the magnetization directions of the free magnetic layers are directed in the same direction is different.
  • the sensor output 56 in the ideal state changes linearly in proportion to the magnitude of the magnetic field to be measured.
  • the actual sensor output 58 shows a value deviated from the sensor output 56 in the ideal state due to the inclination of the magnetic field to be measured, and is not completely a straight line.
  • the sensor output range in the measurement range is “FS”
  • the difference between the ideal sensor output 56 and the actual sensor output 58 in the maximum measured magnetic field in the measurement range is “ ⁇ V f ”.
  • the linearity value increases as the gradient of the measured magnetic field increases, and ⁇ 20 ° When tilted, it exhibits a linearity of about 4% to 4.5%. That is, the linearity of the sensor output is reduced.
  • the linearity of the magnetic sensor 10 of this example is suppressed to 0.3% or less in the range where the gradient of the magnetic field to be measured is ⁇ 20 °. Therefore, the magnetic sensor 10 of the present embodiment can suppress a decrease in linearity of the sensor output.
  • the magnetic sensor 10 suppresses a decrease in linearity of the sensor output due to a deviation in the direction of the magnetic field 30 to be measured and prevents a change in the direction of the bias magnetic field 29 due to an external magnetic field.
  • the magnetization direction 47a of the free magnetic layer 47 can be controlled.
  • FIG. 10A is a graph showing the relationship between the coil magnetic field and hysteresis in the magnetic sensor of the example
  • FIG. 10B is a graph for explaining the hysteresis of the output of the magnetic sensor.
  • hysteresis of the free magnetic layer 47 due to the hysteresis of the free magnetic layer 47, hysteresis of the sensor output occurs as shown in FIG. Further, when a strong magnetic field is applied from the outside, there arises a problem that the free magnetic layer 47 becomes multi-domain and the hysteresis increases.
  • the bias magnetic field 29 applied to the free magnetic layer increases and the hysteresis tends to decrease.
  • the hysteresis can be made almost zero in the range where the coil magnetic field is 2.7 mT or more.
  • the sensor sensitivity tends to decrease.
  • the magnetic domain of the free magnetic layer 47 is initialized (reset). )can do. Thereby, the hysteresis of the magnetic sensor 10 can be reduced.
  • the initialization (reset) of the free magnetic layer 47 by applying a pulsed coil magnetic field can be used in combination with the sensor detection described above. For example, at the time of detecting a normal external magnetic field, a coil magnetic field of about 0.5 mT to 2.0 mT as shown in FIG.
  • the free magnetic layer 47 can be initialized by applying a strong coil magnetic field.
  • FIG. 11 shows the magnetic sensor 11 of the second embodiment.
  • FIG. 11 shows a state in which the coils formed on the magnetoresistive effect elements 21a to 21d are removed, and in this embodiment as well as FIG. 1, the magnetoresistive effect elements 21a to 21d are placed on the magnetoresistive effect elements 21a to 21d.
  • a coil 27 is provided.
  • a pair of magnetoresistive effect elements 21a and 21b constituting the first half-bridge circuit 51 are arranged adjacent to each other on the Y1 side
  • the second A pair of magnetoresistive elements 21c and 21d constituting the half bridge circuit 52 are arranged adjacent to each other on the Y2 side.
  • the magnetization directions 45a of the pinned magnetic layers 45 of the pair of magnetoresistive elements 21a and 21b are directed in opposite directions, and the magnetization directions 47a of the free magnetic layers are directed in opposite directions. It has been. Therefore, as in FIGS. 7A and 7B, the change in sensitivity of the magnetoresistive effect element 21a and the change in sensitivity of the magnetoresistive effect element 21b are offset to suppress a decrease in linearity of the sensor output. it can.
  • a bias magnetic field 29 is generated by passing a current through the coil 27, so that the free magnetic layers 47 of the pair of magnetoresistive elements 21a and 21b are opposite to each other.
  • a bias magnetic field 29 can be applied in the direction.
  • the sensor output linearity caused by the deviation of the direction of the magnetic field to be measured 30 is suppressed, and the change in the direction of the bias magnetic field 29 due to the external magnetic field is prevented, thereby allowing free movement. It is possible to control the magnetization direction 47 a of the magnetic layer 47.
  • FIG. 12 shows the magnetic sensor of the third embodiment and is a circuit diagram of a half bridge circuit composed of two magnetoresistive elements.
  • the magnetic sensor 10 of the first embodiment and the magnetic sensor 11 of the second embodiment form a full bridge circuit 53 by four magnetoresistive effect elements 21a to 21d, but the magnetic sensor 12 of the present embodiment The difference is that it is composed of one half-bridge circuit 51 having two magnetoresistive elements 21a and 21b.
  • the ( ⁇ ) terminal that is different from the terminal ((+) terminal) connected to the midpoint of the magnetoresistive effect elements 21a and 21b at the input terminal of the amplifier is connected to GND (ground) or a constant voltage via a resistor. Yes.
  • the single half-bridge circuit 51 can detect the magnetic field to be measured.
  • a pair of magnetoresistive elements 21a and 21b constituting one half-bridge circuit 51 are formed, the magnetization directions 45a of the pinned magnetic layer 45 are opposite to each other, and the magnetization directions 47a of the free magnetic layer are opposite to each other.
  • the magnetic field to be measured can be detected by disposing it so as to face the screen. As shown in FIG. 12, the fluctuation of the midpoint potential (V1) when the magnetic field to be measured is applied is amplified by the differential amplifier 54 and output as a sensor output.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Magnetic Variables (AREA)
  • Hall/Mr Elements (AREA)

Abstract

Le problème décrit par la présente invention est de proposer un capteur magnétique qui permet de réduire au minimum la dégradation de la linéarité de la sortie dudit capteur due aux déviations dans la direction du champ magnétique mesuré, d'empêcher les changements de direction d'un champ magnétique de polarisation dus à un champ magnétique externe et d'ajuster la direction de magnétisation d'une couche libre. La solution selon l'invention porte sur l'inclusion d'une paire d'éléments magnétorésistifs (21a, 21b) et d'une bobine (27) disposée au-dessus desdits éléments magnétorésistifs (21a, 21b). L'invention est également caractérisé en ce que : chacun des éléments magnétorésistifs (21a, 21b) comprend une couche piégée qui a une direction fixe de magnétisation et une couche libre dont la direction de magnétisation varie du fait des champs magnétiques externes ; les directions de magnétisation (45a) des couches piégées des éléments magnétorésistifs respectifs (21a, 21b) sont opposée les unes par rapport aux autres ; les directions de magnétisation (47a) des couches libres sont également opposées les unes par rapport aux autres ; et les fils constituant la bobine (27) croisent la direction dans laquelle les couches libres s'étendent.
PCT/JP2015/053922 2014-02-19 2015-02-13 Capteur magnétique WO2015125699A1 (fr)

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JP2014-029778 2014-02-19
JP2014029778 2014-02-19
JP2014137093A JP2017072375A (ja) 2014-02-19 2014-07-02 磁気センサ
JP2014-137093 2014-07-02

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Publication number Priority date Publication date Assignee Title
CN113574694A (zh) * 2019-04-09 2021-10-29 株式会社村田制作所 磁阻元件及磁传感器
US11686788B2 (en) 2021-07-08 2023-06-27 Tdk Corporation Magnetic sensor device and magnetic sensor system

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JP2000035471A (ja) * 1998-07-17 2000-02-02 Alps Electric Co Ltd 巨大磁気抵抗効果素子を備えたポテンショメータ
JP2005291728A (ja) * 2004-03-31 2005-10-20 Hitachi Metals Ltd 巨大磁気抵抗素子を持った方位計
JP2007218700A (ja) * 2006-02-15 2007-08-30 Tdk Corp 磁気センサおよび電流センサ
JP2011154032A (ja) * 2011-03-11 2011-08-11 Yamaha Corp 磁気センサの製法
WO2012172946A1 (fr) * 2011-06-13 2012-12-20 アルプス・グリーンデバイス株式会社 Capteur de courant électrique
JP2013200303A (ja) * 2012-02-20 2013-10-03 Hitachi Metals Ltd 磁気センサ装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000035471A (ja) * 1998-07-17 2000-02-02 Alps Electric Co Ltd 巨大磁気抵抗効果素子を備えたポテンショメータ
JP2005291728A (ja) * 2004-03-31 2005-10-20 Hitachi Metals Ltd 巨大磁気抵抗素子を持った方位計
JP2007218700A (ja) * 2006-02-15 2007-08-30 Tdk Corp 磁気センサおよび電流センサ
JP2011154032A (ja) * 2011-03-11 2011-08-11 Yamaha Corp 磁気センサの製法
WO2012172946A1 (fr) * 2011-06-13 2012-12-20 アルプス・グリーンデバイス株式会社 Capteur de courant électrique
JP2013200303A (ja) * 2012-02-20 2013-10-03 Hitachi Metals Ltd 磁気センサ装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113574694A (zh) * 2019-04-09 2021-10-29 株式会社村田制作所 磁阻元件及磁传感器
CN113574694B (zh) * 2019-04-09 2024-01-05 株式会社村田制作所 磁阻元件及磁传感器
US11686788B2 (en) 2021-07-08 2023-06-27 Tdk Corporation Magnetic sensor device and magnetic sensor system
US11946989B2 (en) 2021-07-08 2024-04-02 Tdk Corporation Magnetic sensor device and magnetic sensor system

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