WO2012120940A1 - Capteur de courant - Google Patents

Capteur de courant Download PDF

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Publication number
WO2012120940A1
WO2012120940A1 PCT/JP2012/051850 JP2012051850W WO2012120940A1 WO 2012120940 A1 WO2012120940 A1 WO 2012120940A1 JP 2012051850 W JP2012051850 W JP 2012051850W WO 2012120940 A1 WO2012120940 A1 WO 2012120940A1
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Prior art keywords
film
alloy film
layer
current sensor
magnetoresistive effect
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PCT/JP2012/051850
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English (en)
Japanese (ja)
Inventor
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 to JP2013503419A priority Critical patent/JP5597305B2/ja
Publication of WO2012120940A1 publication Critical patent/WO2012120940A1/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
    • G01R33/093—Magnetoresistive devices using multilayer structures, e.g. giant magnetoresistance sensors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • 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
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices

Definitions

  • the present invention relates to a current sensor using a magnetoresistive effect element.
  • a motor In an electric vehicle, a motor is driven using electricity generated by an engine or a regenerative brake.
  • the magnitude of the current used for driving the motor is detected by, for example, a non-contact current sensor.
  • a current sensor a sensor in which a magnetic core having a notch (core gap) is arranged around a conductor through which a current to be measured flows and a magnetic detection element is arranged in the core gap is known.
  • the magnetic sensor of the current sensor described above has a laminated structure of a fixed magnetic layer whose magnetization direction is fixed, a nonmagnetic layer, and a free magnetic layer (soft magnetic free layer) whose magnetization direction varies with respect to an external magnetic field.
  • a magnetoresistive element or the like is used.
  • the current sensor using a magnetoresistive effect element includes a bridge circuit including a magnetoresistive effect element and a fixed resistance element as a magnetic field detection circuit (see, for example, Patent Document 1).
  • various characteristics such as dynamic range (current measurement range) and linearity (output linearity) greatly depend on the characteristics of the magnetoresistive effect element constituting the current sensor.
  • GMR giant magnetoresistive effect
  • the dynamic range of the current sensor depends on the linearity of the magnetic field-resistance change rate curve of the GMR element. . That is, if the linear region of the magnetic field-resistance change rate curve of the GMR element becomes wider, the dynamic range of the current sensor becomes wider.
  • a thick free magnetic layer in the GMR element may be formed.
  • the slope of the magnetic field-resistance change rate curve is reduced, so that the resistance change rate can be made linear over a wide magnetic field range.
  • the method of canceling the AMR effect by setting the thickness of the free magnetic layer to 5 nm or less can obtain a GMR element suitable for the use of the magnetic head. Since the anisotropy is small, it is impossible to achieve both high linearity and low magnetic hysteresis. In particular, since the thickness of the free magnetic layer is as thin as 5 nm or less, it is difficult to keep the magnetic hysteresis low. For this reason, even if the GMR element is used as a current sensor, it is difficult to realize a current sensor having a wide dynamic range, low magnetic hysteresis, and high current detection accuracy.
  • the present invention has been made in view of such a point, and an object thereof is to provide a current sensor having a wide dynamic range, low magnetic hysteresis, and high current detection accuracy.
  • the current sensor of the present invention is a current sensor including a magnetoresistive effect element whose resistance value is changed by application of an induced magnetic field from a current to be measured, and the magnetoresistive effect element is inserted through an antiparallel coupling film.
  • a self-pinned ferromagnetic pinned layer formed by antiferromagnetically coupling the first ferromagnetic film and the second ferromagnetic film, a nonmagnetic intermediate layer on the ferromagnetic pinned layer, and the nonmagnetic intermediate layer
  • a soft magnetic free layer (free magnetic layer) on the layer, and the soft magnetic free layer includes a CoFe alloy film on the nonmagnetic intermediate layer, a NiFe alloy film on the CoFe alloy film, and the NiFe alloy.
  • NiFeM alloy film (M is an element selected from Ta, Cr, Nb, Rh, Zr, Mo, Al, Au, Pd, Pt, and Si), and the CoFe alloy film
  • the thickness is 0.5 nm to 1.5 nm
  • the thickness of the iFe alloy film is 0.5 nm ⁇ 2.0 nm
  • the thickness of NiFeM alloy film is 6 nm ⁇ 17 nm.
  • the soft magnetic free layer in the magnetoresistive effect element has a laminated structure of a relatively thin CoFe alloy film and NiFe alloy film and a relatively thick NiFeM alloy film, linearity is improved.
  • a magnetoresistive element with improved MR ratio and reduced coercive force is realized. This is because the MR ratio is increased by the NiFe alloy film having a predetermined thickness disposed on the CoFe alloy film, and the coercive force is maintained while maintaining the MR ratio by the NiFeM alloy film having the predetermined thickness disposed on the NiFe alloy film. This is because it can be suppressed.
  • the linearity can be improved by increasing the thickness of the NiFeM alloy film having a small AMR effect and reducing the thickness of the NiFe alloy film having a large AMR effect. Also, by setting the CoFe alloy film to the above thickness, while suppressing magnetostriction and magnetic hysteresis, the thermal diffusion of the film constituting the laminated structure of the magnetoresistive effect element is prevented, and the spin-dependent interface scattering effect is enhanced. This is because the ratio can be increased. As a result of realizing a magnetic sensor element suitable for the current sensor as described above, a current sensor having a wide dynamic range, low magnetic hysteresis, and high current detection accuracy is realized.
  • the CoFe alloy film may be made of a CoFe alloy containing 0 atomic% to 20 atomic% of Fe. That is, the CoFe alloy film may be a Co film. According to this configuration, since the CoFe alloy has a face-centered cubic structure (fcc) or a hexagonal close-packed structure (hcp), magnetic hysteresis can be further suppressed.
  • fcc face-centered cubic structure
  • hcp hexagonal close-packed structure
  • the NiFe alloy film may be composed of a NiFe alloy containing 16 atomic% to 22 atomic% of Fe. According to this configuration, since the linear magnetostriction constant of the NiFe alloy is close to zero, dispersion of magnetic anisotropy due to the magnetoelastic effect can be suppressed.
  • the NiFeM alloy film may be composed of a NiFeM alloy containing 10 atomic% to 15 atomic% Fe and 2 atomic% to 8 atomic% M. According to this configuration, since the linear magnetostriction constant of the NiFeM alloy is close to zero, dispersion of magnetic anisotropy due to the magnetoelastic effect can be suppressed.
  • a magnetic field detection bridge circuit including the magnetoresistive effect element and the fixed resistance element may be provided.
  • the magnetic field detection bridge circuit is configured using the magnetoresistive effect element and the fixed resistance element as described above, a current having a wide dynamic range, low magnetic hysteresis, and high current detection accuracy.
  • the sensor is realized.
  • a current sensor having a wide dynamic range, low magnetic hysteresis, and high current detection accuracy can be provided.
  • FIGS. 1 and 2 are schematic views showing an example of a current sensor according to an embodiment of the present invention.
  • the current sensor shown in FIGS. 1 and 2 is a magnetic proportional current sensor and is disposed in the vicinity of the conductor 11 through which the current I to be measured flows.
  • a magnetic proportional current sensor will be described, but the current sensor is not limited thereto.
  • a magnetic balance equation that generates a canceling magnetic field that cancels the induced magnetic field by the feedback coil and calculates the magnitude of the current to be measured from the current flowing through the feedback coil may be applied.
  • the current sensor shown in FIG. 1 and FIG. 2 has a magnetic field detection bridge circuit 12 that detects an induced magnetic field due to the current I to be measured flowing through the conductor 11.
  • the magnetic field detection bridge circuit 12 includes two magnetoresistive effect elements 12a and 12b whose resistance values are changed by applying an induction magnetic field from the current I to be measured, and two fixed resistance elements 12c and 12d whose resistance values are not changed by the induction magnetic field.
  • the magnetic field detection bridge circuit 12 is not limited to a full bridge circuit composed of four elements. A half-bridge circuit composed of two elements may be used.
  • the magnetic field detection bridge circuit 12 includes two output terminals Out1 and Out2 that generate a voltage difference corresponding to the induced magnetic field caused by the current I to be measured.
  • a power source Vdd is connected to one end of the magnetoresistive effect element 12a and one end of the fixed resistance element 12d, and one end of the magnetoresistive effect element 12b and one end of the fixed resistance element 12c. Is connected to the ground GND.
  • the other end of the magnetoresistive effect element 12a and the other end of the fixed resistance element 12c are connected to form an output end Out1, and the other end of the magnetoresistive effect element 12b and the other end of the fixed resistance element 12d Are connected to form an output terminal Out2.
  • the current sensor Based on the voltage difference output from the output terminals Out1 and Out2, the current sensor calculates the current value of the current I to be measured.
  • FIG. 3 is a cross-sectional view showing the current sensor shown in FIG.
  • magnetoresistive elements 12 a and 12 b constituting the magnetic field detection bridge circuit 12 are formed on the substrate 21.
  • a magnetic shield that attenuates the induced magnetic field A caused by the current I to be measured may be disposed on the magnetoresistive effect elements 12a and 12b. By arranging the magnetic shield, the induced magnetic field A applied to the magnetoresistive effect elements 12a and 12b is weakened, so that the substantial current measurement range of the current sensor can be expanded.
  • the magnetic shield can be configured using a high magnetic permeability material such as an amorphous magnetic material, a permalloy magnetic material, or an iron microcrystalline material.
  • a thermal silicon oxide film 22 that is an insulating layer is formed on a substrate 21.
  • An aluminum oxide film 23 is formed on the thermal silicon oxide film 22.
  • the aluminum oxide film 23 can be formed by a method such as sputtering. Further, a silicon substrate or the like is used as the substrate 21.
  • magnetoresistive effect elements 12a and 12b and fixed resistance elements 12c and 12d are formed, and the magnetic field detection bridge circuit 12 described above is formed.
  • the magnetoresistive effect elements 12a and 12b are formed by folding back a plurality of strip-like long patterns (stripes) arranged so that their longitudinal directions are parallel to each other (meander shape). It is preferable that the GMR element has The film configuration of the magnetoresistive effect elements 12a and 12b will be described later.
  • the sensitivity axis direction (Pin direction) of the magnetoresistive effect elements 12a and 12b is a direction (stripe width direction) orthogonal to the longitudinal direction (stripe longitudinal direction) of the long pattern in the meander shape described above. That is, from the viewpoint of improving linearity, it is preferable that the meandering shape is configured such that the induced magnetic field A faces in the direction perpendicular to the stripe longitudinal direction (stripe width direction).
  • the width in the meander-shaped pin direction is preferably 1 ⁇ m to 10 ⁇ m.
  • An electrode 24 is formed on the aluminum oxide film 23.
  • the electrode 24 can be formed by photolithography and etching after forming an electrode material.
  • a polyimide layer 25 is formed as an insulating layer on the aluminum oxide film 23 on which the magnetoresistive effect elements 12a and 12b, the fixed resistance elements 12c and 12d, and the electrode 24 are formed.
  • the polyimide layer 25 can be formed by applying and curing a polyimide material.
  • a silicon oxide film 31 is formed on the polyimide layer 25.
  • the silicon oxide film 31 can be formed by a method such as sputtering.
  • a contact hole is formed in a predetermined region of the polyimide layer 25 and the silicon oxide film 31 (region where the electrode 24 exists), and an electrode pad 26 is formed in the contact hole. Photolithography, etching, and the like are used for forming the contact holes.
  • the electrode pad 26 can be formed by photolithography and plating after the electrode material is deposited.
  • FIG. 4 is a schematic cross-sectional view showing the film configuration of the magnetoresistive effect element 12a. That is, the magnetoresistive effect element 12a has a laminated structure provided on the substrate 21, as shown in FIG. In FIG. 4, the configuration other than the substrate 21 and the magnetoresistive effect element 12a is omitted for the sake of simplicity. Further, since the film configuration of the magnetoresistive effect element 12b is the same as that of the magnetoresistive effect element 12a except for the Pin direction, the film configuration of the magnetoresistive effect element 12a will be described here.
  • the magnetoresistive effect element 12a includes a seed layer 42, a first ferromagnetic film 43, an antiparallel coupling film 44, a second ferromagnetic film 45, a nonmagnetic intermediate layer 46, a soft magnetic free layer (free magnetic layer) 47, And a protective layer 48.
  • the first ferromagnetic film 43 and the second ferromagnetic film 45 are antiferromagnetically coupled via the antiparallel coupling film 44, so-called self-pinning type ferromagnetic.
  • a fixed layer (SFP layer: Synthetic Ferri Pinned layer) is configured.
  • the magnetoresistive effect element 12 a is a spin valve type element using the ferromagnetic pinned layer, the nonmagnetic intermediate layer 46 and the soft magnetic free layer 47.
  • the seed layer 42 is made of NiFeCr or Cr.
  • a base layer made of a nonmagnetic material containing at least one element of Ta, Hf, Nb, Zr, Ti, Mo, and W is provided between the substrate 21 and the seed layer 42, for example. Also good.
  • the first ferromagnetic film 43 is preferably made of a CoFe alloy containing 40 atomic% to 80 atomic% of Fe. This is because a CoFe alloy having this composition range has a large coercive force and can stably maintain magnetization with respect to an external magnetic field.
  • the first ferromagnetic film 43 is provided with induced magnetic anisotropy by applying a magnetic field in the meander-shaped stripe width direction during the film formation. The direction of the applied magnetic field is the direction from the back side to the near side.
  • the antiparallel coupling film 44 is made of Ru or the like.
  • the antiparallel coupling film 44 is desirably formed with a thickness of 0.3 nm to 0.45 nm or 0.75 nm to 0.95 nm. This is because by setting the antiparallel coupling film 44 to such a thickness, strong antiferromagnetic coupling can be provided between the first ferromagnetic film 43 and the second ferromagnetic film 45.
  • the second ferromagnetic film 45 is preferably made of a CoFe alloy containing 0 atomic% to 40 atomic% of Fe. This is because a CoFe alloy having this composition range has a small coercive force, and is easily magnetized in a direction antiparallel to the direction in which the first ferromagnetic film 43 is preferentially magnetized (direction different by 180 °). is there.
  • the second ferromagnetic film 45 has a magnetic field similar to that during the film formation of the first ferromagnetic film 43 (a magnetic field in the meander stripe width direction, a direction from the back side to the front side of the drawing). Is applied), induced magnetic anisotropy is imparted.
  • the first ferromagnetic film 43 is preferentially magnetized in the direction of the applied magnetic field, and the second ferromagnetic film 45 is magnetized by the first ferromagnetic film 43.
  • the direction is magnetized in an antiparallel direction (a direction different by 180 °).
  • the nonmagnetic intermediate layer 46 is made of Cu or the like.
  • the soft magnetic free layer (free magnetic layer) 47 is composed of a laminated structure of films made of a magnetic material. Specifically, it has a three-layer structure of a CoFe alloy film 471, a NiFe alloy film 472, and a NiFeM alloy film 473.
  • M represents an element selected from Ta, Cr, Nb, Rh, Zr, Mo, Al, Au, Pd, Pt, and Si.
  • the thickness of the CoFe alloy film 471 is 0.5 nm to 1.5 nm, more preferably 0.8 nm to 1.2 nm, and the thickness of the NiFe alloy film 472 is 0.5 nm to 2.0 nm, more preferably The thickness of the NiFeM alloy film 473 is 6 nm to 17 nm, more preferably 9 nm to 14 nm.
  • the MR ratio is increased by the NiFe alloy film 472 disposed on the CoFe alloy film 471, and the coercive force can be suppressed while maintaining the MR ratio by the NiFeM alloy film 473 disposed on the NiFe alloy film 472. is there.
  • the linearity can be improved by increasing the thickness of the NiFeM alloy film having a small AMR effect and reducing the thickness of the NiFe alloy film having a large AMR effect.
  • it is desirable that the ratio t1 / t2 between the thickness t1 of the NiFe alloy film and the thickness t2 of the NiFeM alloy film is 3 to 30.
  • the CoFe alloy film 471 is preferably composed of a CoFe alloy containing 0 atomic% to 20 atomic% of Fe. That is, the CoFe alloy film may be a Co film. With such a composition, since the CoFe alloy has a face-centered cubic structure (fcc) or a hexagonal close-packed structure (hcp), magnetic hysteresis can be further suppressed. Further, the NiFe alloy film 472 is preferably composed of a NiFe alloy containing 16 atomic% to 22 atomic% of Fe, and the NiFeM alloy film 473 is composed of 10 atomic% to 15 atomic% Fe and 2 atomic% to 8 atomic%.
  • NiFeM alloy containing atomic% M It is desirable to be composed of a NiFeM alloy containing atomic% M. In such a composition, since the linear magnetostriction constants of the NiFe alloy and the NiFeM alloy are close to zero, dispersion of magnetic anisotropy due to the magnetoelastic effect can be suppressed.
  • the soft magnetic free layer 47 is preferably provided with induced magnetic anisotropy by applying a magnetic field in the longitudinal direction of the meander-shaped stripe during film formation. Thereby, a resistance change linearly with respect to the external magnetic field in the stripe width direction and a magnetoresistive effect element 12a having a small magnetic hysteresis can be realized.
  • the protective layer 48 is made of Ta or the like.
  • the linearity is improved, the MR ratio is improved, and the coercive force is suppressed.
  • the resistance effect element 12a is realized.
  • the improvement of the linearity of the magnetoresistive effect element 12a contributes to the expansion of the dynamic range and the current detection accuracy in the current sensor, and the improvement of the MR ratio of the magnetoresistive effect element 12a improves the current detection accuracy in the current sensor.
  • the suppression of the coercive force of the magnetoresistive effect element 12a contributes to the reduction of magnetic hysteresis in the current sensor. For this reason, the magnetoresistive effect element 12a is suitable for a current sensor.
  • the magnetization amount (Ms ⁇ t) of the first ferromagnetic film 43 and the magnetization amount (Ms ⁇ t) of the second ferromagnetic film 45 are substantially the same.
  • the difference in magnetization between the first ferromagnetic film 43 and the second ferromagnetic film 45 is substantially zero, the effective anisotropic magnetic field of the ferromagnetic fixed layer is increased. This is because the magnetization stability of the ferromagnetic pinned layer can be sufficiently secured without using an antiferromagnetic material.
  • the Curie temperature (Tc) of the first ferromagnetic film 43 and the Curie temperature (Tc) of the second ferromagnetic film 45 are substantially the same. Thereby, even in a high temperature environment, the difference in magnetization (Ms ⁇ t) between the first ferromagnetic film 43 and the second ferromagnetic film 45 becomes substantially zero, and high magnetization stability can be maintained. It is.
  • FIG. 5 is a graph showing an RH waveform (magnetic field-resistance change rate curve) of the magnetoresistive effect element.
  • the solid line shows the RH waveform of the magnetoresistive effect element (implementing element) in the present embodiment
  • the broken line shows the RH waveform of the conventional magnetoresistive effect element (comparative element).
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 (Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: 1 nm) / Ni 82
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: 7 nm) / Ta (protection)
  • a magnetoresistive element having a film configuration of (layer: 10 nm) was used. That is, only the configuration of the soft magnetic free layer is different between the implementation element and the comparison element. Note that the RH waveform shown in FIG. 5 was obtained under conditions that are normally measured.
  • FIG. 5 confirms that the linearity of the graph of the implementation element in the present embodiment is higher than that of the comparison element, and the linearity is enhanced.
  • the improvement of the linearity brings about the effect of increasing the dynamic range and improving the current detection accuracy in the current sensor.
  • FIG. 6 is a graph showing the relationship between the film thickness of the NiFe alloy film 472 and the MR ratio ( ⁇ R / R) in the magnetoresistive effect element (implementing element).
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 second Ferromagnetic film: 2.4 nm) / Cu
  • Co 90 Fe 10 soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: X 1 nm) / Ni 82 Fe 13
  • a NiFe alloy film having a film thickness X 1 different between 0 nm and 3 nm can be used as a magnetoresistive effect element having a film configuration of Nb 5 (soft magnetic free layer: 9 nm) / Ta (protective layer: 10 nm).
  • FIG. 7 is a graph showing the relationship between the amount of magnetization (Ms ⁇ t) of the soft magnetic free layer and the coercive force (Hc) in the magnetoresistive effect element.
  • the solid line indicates the relationship in the magnetoresistive effect element (implementing element) of the present embodiment, and the broken line indicates the relationship in the conventional magnetoresistive effect element (comparative element).
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 (Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: 2 nm) / Ni 82
  • a magnetoresistive element having a film structure of Fe 13 Nb 5 (soft magnetic free layer: X 2 nm) / Ta (protective layer: 10 nm) and changing the film thickness X 2 of the NiFeNb alloy film, the amount of magnetization is changed. And the relationship with the coercive force was obtained.
  • the film thickness X 2 values at the measurement points (unit n) the film thickness X 2 values at the measurement points (unit n
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: Y 2 nm) / Ta (protective layer: 10 nm) using a magnetoresistive element of a membrane structure that, similarly changing the magnetization by varying the thickness Y 2 of the NiFe alloy film, obtained relation between the coercive force. That is, only the configuration of the soft magnetic free layer is different between the implementation element and the comparison element. In the characteristic shown by the broken line in FIG. 7, the thickness Y 2 of the values at the measurement points (unit nm) are also shown.
  • the coercive force hardly changes even when the value of the magnetization amount changes, but in the comparison element, the coercive force increases as the magnetization amount increases. I can confirm that.
  • a large coercive force means that the magnetic hysteresis is large. Therefore, the magnetoresistive effect element in which the coercive force is suppressed brings about an effect of reducing the magnetic hysteresis in the current sensor.
  • FIG. 8 is a graph showing the relationship between the magnetization amount (Ms ⁇ t) of the soft magnetic free layer and the MR ratio ( ⁇ R / R) in the magnetoresistive effect element.
  • the solid line indicates the relationship in the magnetoresistive effect element (implementing element) of the present embodiment
  • the broken line indicates the relationship in the conventional magnetoresistive effect element (comparative element)
  • the alternate long and short dash line is for reference. The relationship in the magnetoresistive element (reference element) is shown.
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 (Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: 2 nm) / Ni 82
  • a magnetoresistive element having a film structure of Fe 13 Nb 5 (soft magnetic free layer: X 3 nm) / Ta (protective layer: 10 nm) and changing the film thickness X 3 of the NiFeNb alloy film, the amount of magnetization is changed.
  • the relationship with the MR ratio was obtained.
  • the thickness X 3 of NiFeNb alloy film was varied between 3 nm ⁇ 15 nm. In the characteristic shown by the solid line in FIG. 8, the film thickness X 3 value at the measurement point (in nm) shown together.
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / NiFe (soft magnetic free layer: Y 3 nm) / Ta (protective layer: 10 nm) using a magnetoresistive element of a membrane structure that, similarly changing the magnetization by varying the thickness Y 3 of the NiFe alloy film, obtained relation between MR ratio.
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / Ni 82 Fe 13 Nb 5 (soft magnetic free layer: Z 3 nm) / Ta (protective layer: 10 nm) using a magnetoresistive effect element, and similarly changing the film thickness Z 3 of the NiFeNb alloy film to change the amount of magnetization and obtaining the relationship with the MR ratio.
  • FIG. 8 confirms that the magnetoresistive effect element (implementing element) according to the present embodiment has a relatively large MR ratio even when the amount of magnetization increases.
  • the amount of magnetization in order to ensure the same MR ratio in the comparison element and the reference element, the amount of magnetization must be sufficiently reduced.
  • the shape anisotropy is reduced and the slope of the RH waveform is increased, so that the range in which linearity can be ensured is narrowed.
  • the thickness of the NiFeNb alloy film in the magnetoresistive effect element 12a is preferably 6 nm to 17 nm.
  • FIG. 9 is a graph showing the relationship between the thickness of the CoFe alloy film 471 and the magnetostriction constant ( ⁇ s) in the magnetoresistive effect element.
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 second Ferromagnetic film: 2.4 nm) / Cu
  • Co 90 Fe 10 soft magnetic free layer: X 4 nm) / Ni 81.5 Fe 18.5 (soft magnetic free layer: 2 nm) / Ni 82 Fe 13 Nb 5 (soft magnetic free layer: 9 nm) / Ta (protective layer: 10 nm)
  • the magnetoresistive effect element has a film thickness X 4 of 0.4 nm to 2 nm.
  • the magnetoresistive effect element (implementing element) in the present embodiment
  • the magnetostriction constant ⁇ s becomes ⁇ s ⁇ ⁇ 1 ppm.
  • the absolute value of the magnetostriction constant ⁇ s is greater than 1, the magnetic anisotropy of the soft magnetic free layer is dispersed due to the magnetoelastic effect, and magnetic hysteresis is likely to occur. It is desirable to be 5 nm to 1.5 nm.
  • FIG. 10 is a graph showing an output waveform (magnetic field-output voltage) of a half bridge circuit composed of a magnetoresistive effect element and a fixed resistance element.
  • the solid line shows the output waveform of the half bridge circuit using the magnetoresistive effect element (implementing element) in the present embodiment, and the broken line shows the half bridge using the conventional magnetoresistive effect element (comparative element). The output waveform of the circuit is shown.
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 (Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / Ni 81.5 Fe 18.5 (soft magnetic free Layer: 1 nm) / Ni 82 Fe 13 Nb 5 (soft magnetic free layer: 10 nm) / Ta (protective layer: 10 nm).
  • NiFeCr seed layer: 4.2 nm
  • Fe 60 Co 40 first ferromagnetic film: 1.8 nm
  • Ru anti-parallel coupling film: 0.36 nm
  • Co 90 Fe 10 Second ferromagnetic film: 2.4 nm) / Cu (nonmagnetic intermediate layer: 2.2 nm) / Co 90 Fe 10 (soft magnetic free layer: 1 nm) / Ni 81.5 Fe 18.5 (soft magnetic free layer) : 7 nm) / Ta (protective layer: 10 nm) was used. That is, only the configuration of the soft magnetic free layer is different between the implementation element and the comparison element.
  • the linear region of the output waveform of the half-bridge circuit using the comparison element is about ⁇ 20 Oe, whereas the linear region of the output waveform of the half-bridge circuit using the implementation element in the present embodiment is ⁇ It can be confirmed that it is about 70 Oe.
  • the output of the half bridge circuit corresponds to the output of the current sensor, and it can be seen that the linearity of the output of the current sensor can be enhanced by using the implementation element.
  • FIGS. 11A to 11C and FIGS. 12A to 12C are views for explaining a method of manufacturing the magnetoresistive effect elements 12a and 12b according to the present embodiment.
  • a seed layer 42a, a first ferromagnetic film 43a, an antiparallel coupling film 44a, a second ferromagnetic film 45a, a nonmagnetic intermediate layer 46a, a soft magnetic free layer are formed on a substrate 21.
  • a layer (free magnetic layer) 47a and a protective layer 48a are sequentially formed.
  • both the direction of the magnetic field applied during the formation of the first ferromagnetic film 43a and the direction of the magnetic field applied during the formation of the second ferromagnetic film 45a are from the front side of the drawing. It is a direction toward the side.
  • the first ferromagnetic film 43a is preferentially magnetized in the applied magnetic field direction
  • the second ferromagnetic film 45a is antiparallel to the magnetization direction of the first ferromagnetic film 43a (a direction different by 180 °). ) Is magnetized.
  • the soft magnetic free layer (free magnetic layer) 47a is formed with a three-layer structure of a CoFe alloy film 471a, a NiFe alloy film 472a, and a NiFeM alloy film 473a. Further, during the formation of the soft magnetic free layer (free magnetic layer) 47a, a magnetic field is applied in the longitudinal direction of the meander stripe.
  • a resist layer is formed on the protective layer 48a, and the resist layer 50a is left on the region where the magnetoresistive effect element 12a is formed by photolithography and etching.
  • the exposed laminated film is removed by ion milling or the like to expose the surface on which the magnetoresistive effect element 12b is formed.
  • a free layer (free magnetic layer) 47b and a protective layer 48b are sequentially formed.
  • a magnetic field is applied in the meander-shaped stripe width direction during the formation of the first ferromagnetic film 43b and the second ferromagnetic film 45b.
  • the direction of the applied magnetic field is the direction from the front side to the back side in FIG. Accordingly, the first ferromagnetic film 43a and the second ferromagnetic film 45a are magnetized in the antiparallel direction (direction different by 180 °).
  • the soft magnetic free layer (free magnetic layer) 47b is formed of a three-layered structure of a CoFe alloy film, a NiFe alloy film, and a NiFeM alloy film. During the formation of the soft magnetic free layer (free magnetic layer) 47b, a magnetic field is applied in the longitudinal direction of the meander stripe.
  • a resist is formed on the protective layers 48a and 48b, and the resist layers 51a and 51b are left on the formation regions of the magnetoresistive elements 12a and 12b by photolithography and etching.
  • the exposed laminated film is removed by ion milling or the like to obtain magnetoresistance effect elements 12a and 12b.
  • the soft magnetic free layer of the magnetoresistive effect element is composed of a laminated structure of a relatively thin CoFe alloy film and NiFe alloy film and a relatively thick NiFeM alloy film.
  • a magnetoresistive element with enhanced MR ratio and reduced coercive force is realized. This is because the MR ratio is increased by the NiFe alloy film having a predetermined thickness disposed on the CoFe alloy film, and the coercive force is maintained while maintaining the MR ratio by the NiFeM alloy film having the predetermined thickness disposed on the NiFe alloy film. This is because it can be suppressed.
  • the linearity can be improved by increasing the thickness of the NiFeM alloy film having a small AMR effect and reducing the thickness of the NiFe alloy film having a large AMR effect.
  • the thickness of the CoFe alloy film is set to the above-mentioned thickness, it is possible to prevent thermal diffusion of the film constituting the laminated structure of the magnetoresistive effect element (for example, Cu layer, NiFe layer, etc.) while suppressing magnetostriction and magnetic hysteresis. This is because the spin-dependent interface scattering effect can be enhanced and the MR ratio can be increased.
  • the present invention is not limited to the above embodiment, and can be implemented with various modifications.
  • the materials, connection relations, thicknesses, sizes, manufacturing methods, and the like in the above embodiments can be changed as appropriate.
  • the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.
  • the present invention can be applied to, for example, a current sensor that detects the magnitude of a current for driving a motor of an electric vehicle.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • General Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Hall/Mr Elements (AREA)
  • Measuring Magnetic Variables (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
  • Thin Magnetic Films (AREA)

Abstract

L'invention concerne un capteur de courant ayant une large plage dynamique, une faible hystérésis magnétique, et une haute précision de détection du courant. Le capteur de courant comporte des éléments à effet de résistance magnétique (12a, 12b), et est caractérisé en ce que chacun des éléments à effet de résistance magnétique (12a, 12b) comprend une couche fixe ferromagnétique de type auto-orienté, une couche intermédiaire non magnétique sur la couche fixe ferromagnétique, et une couche libre à aimantation temporaire sur la couche intermédiaire non magnétique, en ce que la couche libre à aimantation temporaire est composée d'une structure stratifiée d'une pellicule d'alliage CoFe sur la couche intermédiaire non magnétique, d'une pellicule d'alliage NiFe sur la pellicule d'alliage CoFe, et d'une pellicule d'alliage NiFeM (M étant un élément sélectionné parmi Ta, Cr, Nb, Rh, Zr, Mo, Al, Au, Pd, Pt, et Si) sur la pellicule d'alliage NiFe, et en ce que l'épaisseur de la pellicule d'alliage CoFe est comprise entre 0,5 nm et 1,5 nm, l'épaisseur de la pellicule d'alliage NiFe est comprise entre 0,5 nm et 2,0 nm, et l'épaisseur de la pellicule d'alliage NiFeM est comprise entre 6 nm et 17 nm.
PCT/JP2012/051850 2011-03-07 2012-01-27 Capteur de courant WO2012120940A1 (fr)

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WO2016098511A1 (fr) * 2014-12-15 2016-06-23 株式会社村田製作所 Capteur de courant
JP2017502298A (ja) * 2013-12-24 2017-01-19 江▲蘇▼多▲維▼科技有限公司Ｍｕｌｔｉｄｉｍｅｎｓｉｏｎ Ｔｅｃｈｎｏｌｏｇｙ Ｃｏ．， Ｌｔｄ． 強磁場用のシングルチップ基準ブリッジ磁気センサ
WO2018037634A1 (fr) * 2016-08-23 2018-03-01 アルプス電気株式会社 Capteur magnétique et capteur de courant
JP2020042038A (ja) * 2019-11-26 2020-03-19 株式会社東芝 磁気センサ、生体細胞検出装置及び診断装置
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JP2017502298A (ja) * 2013-12-24 2017-01-19 江▲蘇▼多▲維▼科技有限公司Ｍｕｌｔｉｄｉｍｅｎｓｉｏｎ Ｔｅｃｈｎｏｌｏｇｙ Ｃｏ．， Ｌｔｄ． 強磁場用のシングルチップ基準ブリッジ磁気センサ
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WO2016098511A1 (fr) * 2014-12-15 2016-06-23 株式会社村田製作所 Capteur de courant
JPWO2018037634A1 (ja) * 2016-08-23 2019-04-11 アルプスアルパイン株式会社 磁気センサおよび電流センサ
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WO2018037634A1 (fr) * 2016-08-23 2018-03-01 アルプス電気株式会社 Capteur magnétique et capteur de courant
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KR102183263B1 (ko) * 2016-08-23 2020-11-26 알프스 알파인 가부시키가이샤 자기 센서 및 전류 센서
CN109643755B (zh) * 2016-08-23 2023-05-19 阿尔卑斯阿尔派株式会社 磁传感器及电流传感器
US11350840B2 (en) 2017-03-21 2022-06-07 Kabushiki Kaisha Toshiba Magnetic sensor, biological cell sensing device, and diagnostic device
JP2020042038A (ja) * 2019-11-26 2020-03-19 株式会社東芝 磁気センサ、生体細胞検出装置及び診断装置
JP2022031282A (ja) * 2019-11-26 2022-02-18 株式会社東芝 磁気センサ、生体細胞検出装置及び診断装置

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