WO2015008718A1 - Magnetic sensor and method for manufacturing same - Google Patents

Magnetic sensor and method for manufacturing same Download PDF

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Publication number
WO2015008718A1
WO2015008718A1 PCT/JP2014/068656 JP2014068656W WO2015008718A1 WO 2015008718 A1 WO2015008718 A1 WO 2015008718A1 JP 2014068656 W JP2014068656 W JP 2014068656W WO 2015008718 A1 WO2015008718 A1 WO 2015008718A1
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layer
magnetization
ferromagnetic metal
ferromagnetic
free layer
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PCT/JP2014/068656
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French (fr)
Japanese (ja)
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卓男 西川
康夫 安藤
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コニカミノルタ株式会社
国立大学法人東北大学
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Priority to JP2015527287A priority Critical patent/JPWO2015008718A1/en
Publication of WO2015008718A1 publication Critical patent/WO2015008718A1/en

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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
    • G01R33/098—Magnetoresistive devices comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
    • 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 magnetic sensor suitable for sensing a weak magnetic field and a manufacturing method thereof.
  • TMR tunnel magnetoresistive element
  • the tunnel magnetoresistive element includes a ferromagnetic metal magnetization fixed layer whose magnetization direction is fixed, a ferromagnetic metal magnetization free layer whose magnetization direction changes under the influence of an external magnetic field, and a ferromagnetic metal magnetization fixed layer And an insulating layer disposed between the ferromagnetic metal magnetization free layer and insulating by a tunnel effect according to the angular difference between the magnetization direction of the ferromagnetic metal magnetization fixed layer and the magnetization direction of the ferromagnetic metal magnetization free layer Change the resistance of the layer.
  • the invention described in Patent Document 1 has an easy magnetization axis of the ferromagnetic metal magnetization free layer in the zero magnetic field in order to increase sensitivity. It is characterized by being in a twisted position with respect to the easy magnetization axis of the magnetization fixed layer. Furthermore, in the invention described in Patent Document 1, the ferromagnetic metal magnetization free layer and the ferromagnetic metal magnetization fixed layer are respectively the first ferromagnetic material, the second ferromagnetic material, and the first ferromagnetic material.
  • the present invention has been made in view of the problems in the prior art described above, and in a magnetic sensor using a tunnel magnetoresistive element, achieves high sensitivity of the tunnel magnetoresistive element and measures magnetism with high accuracy. It is an object of the present invention to provide a magnetic sensor capable of performing the above and a manufacturing method thereof.
  • the invention described in claim 1 for solving the above-mentioned problems is a ferromagnetic metal magnetization fixed layer in which the magnetization direction is fixed, and the ferromagnetic metal magnetization free in which the magnetization direction changes under the influence of an external magnetic field.
  • the ferromagnetic metal magnetization free layer is a magnetic sensor including an amorphous ferromagnet.
  • the “twisted position” refers to a positional relationship in which two straight lines in the space are not parallel and do not intersect, that is, a positional relationship between two straight lines that cannot exist on the same plane.
  • a straight line perpendicular to the two straight lines at the position of twist is called “twist axis”, and the relative angle of the other straight line to one straight line around the twist axis is called “twist angle”.
  • the invention according to claim 2 is characterized in that the easy magnetization axis of the ferromagnetic metal magnetization free layer in a zero magnetic field is in a twisted position with respect to the easy magnetization axis of the ferromagnetic metal magnetization fixed layer.
  • Item 2 The magnetic sensor according to Item 1.
  • the ferromagnetic metal magnetization free layer includes a first ferromagnetic material, a second ferromagnetic material joined to the insulating layer, the first ferromagnetic material, and the second ferromagnetic material.
  • An ultrathin nonmagnetic metal layer sandwiched between the first ferromagnetic material and the second ferromagnetic material, wherein the magnetization direction of the first ferromagnetic material and the magnetization direction of the second ferromagnetic material are: A parallel coupling membrane structure having an exchange coupling force to be parallel, or an antiparallel coupling membrane structure having an exchange coupling force to be antiparallel, 3.
  • the magnetic sensor according to claim 1 wherein the first ferromagnetic body of the ferromagnetic metal magnetization free layer is made of an amorphous ferromagnetic body.
  • the ferromagnetic metal magnetization free layer is an antiparallel coupling film structure in which the second ferromagnetic material is made of CoFeB and the ultrathin nonmagnetic metal layer is made of Ru.
  • the invention according to claim 5 is characterized in that the first ferromagnetic material of the ferromagnetic metal magnetization free layer made of the amorphous ferromagnetic material has a thickness of 10 nm to 100 nm. Magnetic sensor.
  • the invention according to claim 6 is the magnetic sensor according to claim 3, wherein the ultra-thin non-magnetic metal layer has a thickness of 0.4 nm to 1.5 nm.
  • the angle of twist between the easy magnetization axis of the ferromagnetic metal magnetization free layer and the easy magnetization axis of the ferromagnetic metal magnetization fixed layer in a zero magnetic field is 45 degrees to 135 degrees. It is a magnetic sensor as described in any one of Claim 2-6 characterized by the above-mentioned.
  • the invention according to claim 8 is a ferromagnetic metal magnetization fixed layer whose magnetization direction is fixed, a ferromagnetic metal magnetization free layer whose magnetization direction changes under the influence of an external magnetic field, and the ferromagnetic metal An angle between a magnetization direction of the ferromagnetic metal magnetization fixed layer and a magnetization direction of the ferromagnetic metal magnetization free layer having an insulating layer disposed between the magnetization fixed layer and the ferromagnetic metal magnetization free layer; A method of manufacturing a magnetic sensor including a tunnel magnetoresistive element that changes a resistance of the insulating layer by a tunnel effect according to a difference, A first heat treatment is performed at a first temperature while applying an external magnetic field to the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal magnetization free layer before the heat treatment.
  • the ferromagnetic metal magnetization free layer can be easily formed in a zero magnetic field after the heat treatment.
  • the ferromagnetic metal magnetization free layer includes an amorphous ferromagnet, wherein the first temperature is in a range of 300 ° C. to 500 ° C., and the second temperature is in a range of 200 ° C. to 350 ° C. It is a manufacturing method of a magnetic sensor.
  • Amorphous ferromagnets have small magnetic anisotropy and soft magnetism. When applied to a ferromagnetic metal magnetization free layer, the ferromagnetic metal magnetization free layer is affected by an external magnetic field and has a magnetization direction. The property that changes easily, that is, the sensitivity is improved. In addition, since the amorphous ferromagnet can maintain and withstand the amorphous state even in the heat treatment at a higher temperature, the first ferromagnetic magnetic anisotropy is added to the ferromagnetic metal magnetization free layer and the ferromagnetic metal magnetization fixed layer.
  • the first temperature of the heat treatment can be set to a sufficiently high temperature, and the ferromagnetic tunnel junction (MTJ) composed of both layers and the insulating layer therebetween is formed in a high quality state to increase the sensitivity.
  • MTJ ferromagnetic tunnel junction
  • FIG. 1 is a schematic perspective view of a tunnel magnetoresistive element according to an embodiment of the present invention, in which an insulating layer is omitted.
  • 1 is a schematic perspective view of a tunnel magnetoresistive element according to an embodiment of the present invention, in which an insulating layer is omitted.
  • It is a graph which shows transition of the temperature in a furnace in the heat treatment process in a magnetic field of the tunnel magnetoresistive element concerning one embodiment of the present invention.
  • It is a cross-sectional schematic diagram of a laminated structure including an amorphous ferromagnetic film in a preliminary experiment.
  • the present invention relates to a ferromagnetic metal magnetization free layer having a parallel coupling film structure.
  • the present invention relates to a ferromagnetic metal magnetization free layer having an antiparallel coupling film structure.
  • 4 is a graph showing a rate of change in resistance of a TMR element (TMR ratio (%), vertical axis) with respect to an external magnetic field (H (Oe), horizontal axis) according to an example of the present invention.
  • 4 is a graph showing a rate of change in resistance of a TMR element (TMR ratio (%), vertical axis) with respect to an external magnetic field (H (Oe), horizontal axis) according to an example of the present invention.
  • 4 is a graph showing a rate of change in resistance of a TMR element (TMR ratio (%), vertical axis) with respect to an external magnetic field (H (Oe), horizontal axis) according to an example of the present invention.
  • the magnetic sensor of the present embodiment is used for biomagnetic measurement in which a magnetoencephalogram is obtained by measuring a magnetic field emitted from a human skull, and a necessary number of magnetic sensors are incorporated.
  • Various biomagnetism measurement systems are configured to measure a magnetic field emitted from a living body.
  • the magnetism from various magnetic sources is not limited to biomagnetism. It can be used to measure automatically.
  • the magnetic sensor 1 includes a tunnel magnetoresistive element (hereinafter referred to as “TMR element”) 10.
  • TMR element tunnel magnetoresistive element
  • the magnetic sensor 1 includes a lower electrode layer 3, a ferromagnetic metal magnetization free layer 4, an insulating layer 5, a ferromagnetic metal magnetization fixed layer 6, an immobilization promoting layer 7, an upper electrode on a substrate 2. It has a laminated structure in which the layers 8 are sequentially laminated.
  • the TMR element 10 changes the resistance of the insulating layer 5 by the tunnel effect according to the angle difference between the magnetization direction of the ferromagnetic metal magnetization fixed layer 6 and the magnetization direction of the ferromagnetic metal magnetization free layer 4.
  • a power supply 11 for inputting current and a constant resistance 12 are connected in series between the upper electrode layer 8 and the lower electrode layer 3, and a change in resistance value of the insulating layer 5 is detected as a change in voltage value.
  • the magnetic sensor 1 is mounted by being connected to the voltmeter 13. Note that a change in the resistance value of the insulating layer 5 may be detected by applying a voltage to the TMR element 10 and detecting a current flowing through the insulating layer 5 of the TMR element 10.
  • the material of the substrate 2 is not particularly limited as long as it can withstand the formation of each layer, but a substrate having both heat resistance and insulation that can withstand film formation and heat treatment is preferable. Moreover, it is preferable that it is non-magnetic to prevent the magnetic flux from being sucked and the surface is formed relatively smoothly. From such a viewpoint, for example, Si, SiO 2 or the like can be used.
  • the lower electrode layer 3 is composed of three layers 31, 32 and 33.
  • the layer 31 is for adjusting the roughness of the substrate 2, and for example, Ta can be used.
  • the layer thickness of the layer 31 is preferably about 2 nm to 10 nm.
  • Ru can be used as the layer 32 and Ta can be used as the layer 33.
  • the lower electrode layer 3 may be formed of one layer such as Ta alone.
  • the ferromagnetic metal magnetization free layer 4 is a ferromagnetic metal magnetization layer whose magnetization direction changes under the influence of an external magnetic flux, and includes a first ferromagnetic layer 41, an ultrathin nonmagnetic metal layer 42, and the like. And the second ferromagnetic layer 43.
  • the first ferromagnetic layer 41 is made of an amorphous ferromagnetic material.
  • An amorphous ferromagnet has a small magnetic anisotropy and exhibits soft magnetism.
  • the amorphous ferromagnetic material applied to the first ferromagnetic material layer 41 for example, CoFeSiB, CoNbZr, CoZrTa, CoHfTa, or the like can be used.
  • the thickness of the first ferromagnetic layer 41 is preferably 10 nm to 100 nm.
  • the ultrathin nonmagnetic metal layer 42 is for magnetically coupling the first ferromagnetic layer 41 and the second ferromagnetic layer 43 and for separating the latter from the former structure. It is desirable to use a thin film layer having no structure. Specific examples of the material include Ru and Ta.
  • the thickness of the ultrathin nonmagnetic metal layer 42 is preferably 0.4 to 1.5 nm, and more preferably 0.8 nm to 1.3 nm.
  • the second ferromagnetic layer 43 various types can be used. As a typical example, a layer obtained by heat-treating Co40Fe40B20 from an amorphous structure to exhibit ferromagnetism can be used. The crystal structure of this layer is, for example, a body-centered cubic crystal. An Fe-rich material such as Co16Fe64B20 can also be used.
  • the thickness of the second ferromagnetic layer 43 is preferably about 1 to 10 nm. The second ferromagnetic layer 43 is bonded to the lower surface of the insulating layer 5.
  • the ferromagnetic metal magnetization free layer 4 includes the first ferromagnetic layer 41, the second ferromagnetic layer 43, and the ultrathin nonmagnetic metal layer 42 sandwiched between them.
  • the second ferromagnetic body 43 is made of CoFeB and the ultrathin nonmagnetic metal layer 42 is made of Ru
  • the ferromagnetic metal magnetization free layer 4 has a second direction of magnetization of the first ferromagnetic layer 41 and the second direction.
  • An antiparallel coupling film structure having an exchange coupling force in which the magnetization direction of the ferromagnetic layer 43 is antiparallel is formed.
  • the ferromagnetic metal magnetization free layer 4 has the magnetization direction of the first ferromagnetic material layer 41 and A parallel coupling film structure having an exchange coupling force in which the magnetization direction of the second ferromagnetic layer 43 is parallel is configured.
  • parallel and anti-parallel mean that the directions of magnetization are substantially parallel and in the same direction in the former and in the opposite direction in the latter. Includes a case in which the direction of magnetization is in a range that can be regarded as parallel (for example, a range tilted 10 degrees forward and backward).
  • the insulating layer 5 is disposed between the ferromagnetic metal magnetization fixed layer 6 and the ferromagnetic metal magnetization free layer 4.
  • various insulating materials can be used.
  • MgO, AlOx, or the like can be used.
  • MgO is preferable from the viewpoint of improving the sensitivity of the element, and in particular, an MgO film is preferably used as the insulating layer 5 in order to detect a weak magnetic field such as a biomagnetic signal with a tunnel magnetoresistive element.
  • the thickness of the insulating layer 5 is desirably about 1 nm to 10 nm.
  • the ferromagnetic metal magnetization fixed layer 6 is a ferromagnetic metal magnetization layer whose magnetization direction is fixed.
  • the first ferromagnetic layer 61 the same material as the second ferromagnetic layer 43 of the free layer 4, for example, Co40Fe40B20 can be used.
  • the thickness of the first ferromagnetic layer 61 is preferably about 1 to 10 nm.
  • the first ferromagnetic layer 61 is bonded to the upper surface of the insulating layer 5.
  • the ultra-thin non-magnetic metal layer 62 is for magnetically coupling the first ferromagnetic layer 61 and the second ferromagnetic layer 63 and separating the latter from the former crystal structure. It is desirable to use a thin film layer having no crystal structure. Specific examples of the material include Ru.
  • the layer thickness of the ultrathin nonmagnetic metal layer 62 is preferably about 0.5 to 1 nm.
  • the second ferromagnetic layer 63 for example, CoFe can be used.
  • the crystal structure of the second ferromagnetic layer 63 is, for example, a face centered cubic crystal.
  • the layer thickness of the second ferromagnetic layer 63 is preferably about 0.5 nm to 5 nm.
  • the ferromagnetic metal magnetization fixed layer 6 includes the first ferromagnetic layer 61, the second ferromagnetic layer 63, and the ultrathin nonmagnetic metal layer 62 that is sandwiched therebetween. And an antiparallel coupling film structure having an exchange coupling force in which the magnetization direction of the first ferromagnetic layer 61 and the magnetization direction of the second ferromagnetic layer 63 are antiparallel.
  • the immobilization promoting layer 7 is for promoting the immobilization of the second ferromagnetic layer 63, and an antiferromagnetic film such as IrMn or platinum manganese is preferably used.
  • the thickness of the immobilization promoting layer 7 is preferably about 5 nm to 20 nm.
  • the upper electrode layer 8 is composed of two layers 81 and 82.
  • the layer 81 is a base layer of the layer 82 for adjusting the roughness of the immobilization promoting layer 7, and for example, Ta can be used.
  • the layer 81 preferably has a thickness of about 2 nm to 10 nm.
  • the layer 82 is an upper layer to which an electrode is connected, and for example, Au can be used.
  • the layer 82 preferably has a thickness of about 20 nm to 40 nm.
  • Each layer can be formed by, for example, a magnetron sputtering method.
  • heat treatment may be performed as necessary.
  • the easy magnetization axis 4 a of the ferromagnetic metal magnetization free layer 4 in the zero magnetic field is relative to the easy magnetization axis 6 a of the ferromagnetic metal magnetization fixed layer 6.
  • the substrate 2 on which the respective layers are stacked is placed in a furnace and placed in a magnetic field, and two heat treatments with different temperature conditions are performed as shown in FIG.
  • induced magnetic anisotropy is added to the ferromagnetic metal magnetization free layer 4 and the ferromagnetic metal magnetization fixed layer 6, and the easy magnetization axis 4a and strong magnetization of the ferromagnetic metal magnetization free layer 4 are increased.
  • the easy magnetization axis 6a of the magnetic metal magnetization fixed layer 6 is formed.
  • the easy magnetization axis 4a and the easy magnetization axis 6a are in the same direction.
  • the vertex temperature (second temperature) in the temperature transition graph A2 of the second heat treatment is lower than the vertex temperature (first temperature) in the temperature transition graph A1 of the first heat treatment (preferably lower by 10 ° C.
  • the second heat treatment is performed, whereby the easy magnetization axis 6a of the ferromagnetic metal magnetization fixed layer 6 is formed at a twisted position with respect to the easy magnetization axis 4a.
  • the easy magnetization axis 4a is formed along the magnetic field direction during the first heat treatment.
  • the easy magnetization axis 6a is formed along the magnetic field direction during the second heat treatment. Therefore, by changing the magnetic field direction during the second heat treatment with respect to the magnetic field direction during the first heat treatment, the easy magnetization axis 6a can be twisted with respect to the easy magnetization axis 4a.
  • the magnetic field direction during the first heat treatment and the magnetic field direction during the second heat treatment are parallel to the layers.
  • the heat treatment time there is no particular limitation on the heat treatment time, and it may be performed, for example, for about 10 minutes to 2 hours, and it is preferable to make the second heat treatment time shorter than the first heat treatment.
  • the magnetic field in the heat treatment and the magnetic field may be, for example, in the range of 0.01 to 2 [T].
  • the external magnetic field in the second heat treatment is preferably smaller than that in the first heat treatment.
  • the amorphous ferromagnet applied to the first ferromagnet layer 41 can maintain and withstand the amorphous state even during heat treatment at a higher temperature. Therefore, the first temperature of the first heat treatment for adding induced magnetic anisotropy to the ferromagnetic metal magnetization free layer 4 and the ferromagnetic metal magnetization fixed layer 6 can be set to a sufficiently high temperature.
  • a ferromagnetic tunnel junction (MTJ) composed of the layers 4 and 6 and the insulating layer 5 therebetween can be formed in a high quality state to achieve high sensitivity.
  • the first temperature is in the range of 300 ° C. to 500 ° C. and the second temperature is in the range of 200 ° C. to 350 ° C. More preferably, the first temperature is in the range of 350 ° C to 380 ° C.
  • the second temperature is in the range of 250 ° C to 350 ° C.
  • the twist angle ⁇ between the easy magnetization axis 4a and the easy magnetization axis 6a is 90 degrees.
  • FIG. 2B if the easy magnetization axis 4a and the easy magnetization axis 6a are not parallel, the effect of improving the sensitivity is obtained even if the twist angle ⁇ between them is not 90 degrees, but the twist angle ⁇ is 45 It is preferable that the angle is in the range of from 135 degrees to 135 degrees.
  • the area of the ferromagnetic metal magnetization fixed layer 6 is equal to the area of the ferromagnetic metal magnetization free layer 4 or smaller than the area of the ferromagnetic metal magnetization free layer 4 as shown in FIG. 2A or 2B. .
  • the ratio of the area of the ferromagnetic metal magnetization fixed layer 6 to the area of the ferromagnetic metal magnetization free layer 4 is not limited to this, but is preferably set in the range of 1: 1 to 1:10.
  • the ferromagnetic metal magnetization fixed layer 6 is strong when viewed from the substrate 2 supporting the laminated body including the ferromagnetic metal magnetization free layer 4 and the ferromagnetic metal magnetization fixed layer 6. It is formed above the magnetic metal magnetization free layer 4 (that is, on the side farther from the substrate 2). By having such a vertical relationship, the area of the ferromagnetic metal magnetization fixed layer 6 is reduced by the selective etching from the substrate surface on which the ferromagnetic metal magnetization fixed layer 6 and the like are laminated. It is easy to form small with respect to the area.
  • the easy magnetization axis 4a of the ferromagnetic metal magnetization free layer 4 and the easy magnetization axis 6a of the ferromagnetic metal magnetization fixed layer 6 are different from each other in a zero magnetic field.
  • adverse effects such as a leakage magnetic field generated from the ferromagnetic metal magnetization fixed layer 6 are suppressed to be small, and the magnetization of the ferromagnetic metal magnetization free layer 4 becomes an external magnetic field.
  • the sensitivity changes.
  • the area of the ferromagnetic metal magnetization fixed layer 6 is smaller than the area of the ferromagnetic metal magnetization free layer 4, so that also from the fixed layer 6 to the free layer 4.
  • the influence of the leakage magnetic field can be kept small.
  • the ferromagnetic metal magnetization fixed layer 6 is an antiparallel coupling film structure, the leakage magnetic field is reduced, and this also causes leakage from the fixed layer 6 to the free layer 4. The influence of the magnetic field can be kept small.
  • the ferromagnetic metal magnetization free layer 4 is an antiparallel coupling film structure, a stable magnetization film free from leakage magnetic flux can be similarly formed.
  • the first ferromagnet 41 of the ferromagnetic metal magnetization free layer 4 is made of an amorphous ferromagnet, higher sensitivity of the tunnel magnetoresistive element can be achieved at a higher level.
  • high sensitivity of the TMR element can be achieved, and biomagnetism can be measured with high accuracy.
  • a biomagnetic sensor suitable for highly sensitive biomagnetic measurement in the vicinity of zero magnetic field can be obtained.
  • CoFeSiB was adopted as the amorphous ferromagnetic material of the first ferromagnetic layer 41.
  • CoFeSiB was formed as an amorphous ferromagnetic film, heat treatment assuming the first heat treatment was performed, and X-ray crystal structure analysis (XRD) and magnetization characteristic analysis (VSM) were performed.
  • XRD X-ray crystal structure analysis
  • VSM magnetization characteristic analysis
  • a CoFeSiB film a2 having a film thickness d was formed on a silicon substrate a1 by a magnetron sputtering method.
  • argon gas pressure was set to 0.1 Pa
  • sputtering power was set to 30 W
  • four types of samples having a film thickness d of 10, 30, 70, and 100 nm were prepared.
  • FIG. 5A shows an MH curve showing the magnetic field H dependence of the magnetization M measured by the magnetization characteristic analysis (VSM) for the sample at this stage where the film thickness d is 30 nm. Thereafter, heat treatment assuming the first heat treatment is performed. As the heat treatment conditions, there were three heat treatment temperatures of 325 ° C., 350 ° C., and 375 ° C., and the applied magnetic field was 200 (Oe).
  • FIG. 5B shows an MH curve showing the magnetic field H dependence of the magnetization M measured by magnetization characteristic analysis (VSM) on a sample heat-treated at 325 ° C.
  • FIG. 6 shows X-ray diffraction spectra measured by X-ray crystal structure analysis (XRD) for the samples after film formation, before heat treatment (as depo.), And after heat treatment at 325 ° C., 350 ° C., and 375 ° C. Show. In each spectrum of FIG. 6, there was one peak and the diffraction angles coincided, indicating that only Si was detected. This confirmed that the CoFeSiB film was not crystallized at any heat treatment temperature, that is, was amorphous.
  • XRD X-ray crystal structure analysis
  • Ta is 5 nm as layer 31
  • Ru is 10 nm as layer 32
  • Ta is 5 nm as layer 33
  • CoFeSiB is 30 nm as layer 41
  • CoFeB is 3 nm as layer 43
  • MgO is 2.5 nm as layer 5
  • layer 61 CoFeB was 3 nm
  • Ru was 0.85 nm as the layer 62
  • CoFe was 5 nm as the layer 63
  • IrMn was 10 nm as the layer 7
  • Ta was 5 nm as the layer 81
  • Au was 30 nm as the layer 82.
  • Ta is 0.2 nm as the layer 42
  • Ru is Ru as the layer 42.
  • the film thickness was calculated from the film formation speed and the film formation time.
  • Ar ion milling is performed until the layer 43 is reached, whereby the area of the ferromagnetic metal magnetization fixed layer 6 and the area of the ferromagnetic metal magnetization free layer 4 are increased.
  • the resist film was removed by processing to a ratio of 1: 3.5.
  • the sample thus obtained was subjected to heat treatment for 60 minutes at a different temperature for each sample while applying an external magnetic field 1 [T] as the first heat treatment.
  • the second heat treatment is performed while applying an external magnetic field 0.1 [T] in the magnetic field direction that intersects the magnetic field direction of the first heat treatment by 90 degrees.
  • heat treatment was performed for 15 minutes at a different temperature for each sample.
  • a resistor, a power source, and a voltmeter were electrically connected to form a magnetic sensor.
  • the magnetic detection performance of the magnetic sensor thus obtained was measured. Specifically, a sensor to be measured is placed in a Helmholtz coil, and a constant current of several ⁇ A is passed through the sensor, and the magnetic field of the coil is changed from ⁇ 1800 [Oe] to +1800 [Oe] and then ⁇ 1800 [Oe.
  • the sensor resistance change rate (TMR ratio (%)) with respect to the external magnetic field was measured by detecting the output voltage of the sensor. Changes in the TMR ratio depending on the difference in the heat treatment temperature (first temperature Tf) of the first heat treatment are shown in FIGS. 7 relates to the ferromagnetic metal magnetization free layer 4 having a parallel coupling film structure, and FIG.
  • the ferromagnetic metal magnetization free layer 4 having an antiparallel coupling film structure For the ferromagnetic metal magnetization free layer 4 having a parallel coupling film structure, a maximum TMR ratio of 199% was obtained when the first temperature Tf was 350 ° C. as shown in FIG. In the case where the ferromagnetic metal magnetization free layer 4 is an antiparallel coupling film structure, a maximum TMR ratio of 234% was obtained when the first temperature Tf was 375 ° C. as shown in FIG.
  • the linear portion including the zero magnetic field has a steep slope, and the sensitivity is increased as the TMR element resistance changes greatly with respect to the change in the external magnetic field.
  • the slope of the straight line portion can be calculated and evaluated as sensitivity (% / Oe). The higher this value, the higher the sensitivity.
  • the sensitivity of 32.1 (% / Oe) could be achieved, and an unprecedented high sensitivity could be achieved.
  • sensitivity 228%
  • 2Hk 5.7 (Oe)
  • sensitivity 40.0 % / Oe
  • the antiparallel coupling film structure when the antiparallel coupling film structure is applied to the ferromagnetic metal magnetization layer, only one of the ferromagnetic metal magnetization free layer and the ferromagnetic metal magnetization fixed layer is used.
  • An anti-parallel coupling film structure may be applied to the structure, and the effect of making the ferromagnetic metal magnetization free layer an anti-parallel coupling film structure and the effect of making the ferromagnetic metal magnetization fixed layer an anti-parallel coupling film structure are obtained. It is done.
  • the vertical relationship in the lamination of these layers is also arbitrary. As described above, it is advantageous to make the fixed layer an upper layer and to have a small area.
  • the present invention can be used for magnetic field measurement.

Abstract

A magnetic sensor incorporating a tunnel magnetoresistive element, wherein high sensitivity of the tunnel magnetoresistive element is achieved and magnetism is measured with high accuracy. A magnetic sensor having: a ferromagnetic metal magnetization-fixed layer (6) having a fixed magnetization orientation; a ferromagnetic metal magnetization-unrestricted layer (4) in which the orientation of magnetization changes due to the effect of external magnetic fields; and an insulating layer (5) disposed between the ferromagnetic metal magnetization-fixed layer (6) and the ferromagnetic metal magnetization-unrestricted layer (4). The magnetic sensor includes a tunnel magnetoresistive element for allowing the resistance of the insulating layer (5) to be varied by the tunnel effect in accordance with the difference in angle between the orientation of magnetization of the ferromagnetic metal magnetization-fixed layer (6) and the orientation of magnetization of the ferromagnetic metal magnetization-unrestricted layer (4), the ferromagnetic metal magnetization-unrestricted layer (4) including an amorphous ferromagnetic material.

Description

磁気センサー及びその製造方法Magnetic sensor and manufacturing method thereof
　本発明は、微弱な磁界を感知することに適した磁気センサー及びその製造方法に関する。 The present invention relates to a magnetic sensor suitable for sensing a weak magnetic field and a manufacturing method thereof.
　特許文献１にも記載されるように、常温で使用可能で、小型軽薄化、高密度化等が可能なセンサーデバイスとして、トンネル磁気抵抗素子（ＴＭＲ（Tunnel Magneto Resistive）素子）を生体磁気の計測に適用することが提案されている。
　トンネル磁気抵抗素子は、磁化の向きが固定された強磁性金属磁化固定層、外部からの磁界の影響を受けて磁化の向きが変化する強磁性金属磁化自由層、及び、強磁性金属磁化固定層と強磁性金属磁化自由層との間に配置された絶縁層を有し、強磁性金属磁化固定層の磁化の向きと強磁性金属磁化自由層の磁化の向きとの角度差に従ってトンネル効果により絶縁層の抵抗を変化させる。
　特許文献１に記載の発明は、このようなトンネル磁気抵抗素子を含む生体磁気センサーにおいて、高感度化を図るために、ゼロ磁界での強磁性金属磁化自由層の容易磁化軸は、強磁性金属磁化固定層の容易磁化軸に対してねじれの位置にあることを特徴とする。
　さらに特許文献１に記載の発明にあっては、強磁性金属磁化自由層及び強磁性金属磁化固定層はそれぞれ、第１の強磁性体と、第２の強磁性体と、第１の強磁性体と第２の強磁性体との間に挟まれて存在する極薄非磁性体金属層とを備え、第１の強磁性体の磁化の向きと第２の強磁性体の磁化の向きとが反平行になる交換結合力を有する反平行結合膜構造体が採用されている。かかる構造を有する強磁性金属磁化自由層を構成する第１の強磁性体（同文献中符号４１）としては、Ｎｉ７９Ｆｅ２１の適用が例示されている。 As described in Patent Document 1, a tunnel magnetoresistive element (TMR (Tunnel Magneto Resistive) element) is used as a sensor device that can be used at room temperature and can be reduced in size, weight, thickness, and density. It has been proposed to apply to.
The tunnel magnetoresistive element includes a ferromagnetic metal magnetization fixed layer whose magnetization direction is fixed, a ferromagnetic metal magnetization free layer whose magnetization direction changes under the influence of an external magnetic field, and a ferromagnetic metal magnetization fixed layer And an insulating layer disposed between the ferromagnetic metal magnetization free layer and insulating by a tunnel effect according to the angular difference between the magnetization direction of the ferromagnetic metal magnetization fixed layer and the magnetization direction of the ferromagnetic metal magnetization free layer Change the resistance of the layer.
In the biomagnetic sensor including such a tunneling magnetoresistive element, the invention described in Patent Document 1 has an easy magnetization axis of the ferromagnetic metal magnetization free layer in the zero magnetic field in order to increase sensitivity. It is characterized by being in a twisted position with respect to the easy magnetization axis of the magnetization fixed layer.
Furthermore, in the invention described in Patent Document 1, the ferromagnetic metal magnetization free layer and the ferromagnetic metal magnetization fixed layer are respectively the first ferromagnetic material, the second ferromagnetic material, and the first ferromagnetic material. An ultrathin nonmagnetic metal layer sandwiched between the body and the second ferromagnetic body, and the magnetization direction of the first ferromagnetic body and the magnetization direction of the second ferromagnetic body An anti-parallel coupling film structure having an exchange coupling force that becomes anti-parallel is adopted. Application of Ni79Fe21 is exemplified as the first ferromagnetic body (reference numeral 41 in the same document) constituting the ferromagnetic metal magnetization free layer having such a structure.
特開２０１３－１０５８２５号公報JP 2013-105825 A
　しかし、生体磁気信号は非常に微弱であるため、生体磁気信号をトンネル磁気抵抗素子で検出するためには、トンネル磁気抵抗素子の強磁性金属磁化自由層の感度を極限まで高める研究が依然として求められる。 However, since the biomagnetic signal is very weak, in order to detect the biomagnetic signal with the tunnel magnetoresistive element, research for increasing the sensitivity of the ferromagnetic metal magnetization free layer of the tunnel magnetoresistive element is still required. .
　本発明は以上の従来技術における問題に鑑みてなされたものであって、トンネル磁気抵抗素子を利用した磁気センサーにおいて、トンネル磁気抵抗素子の高感度化を達成し、高精度に磁気を計測することができる磁気センサー及びその製造方法を提供することを課題とする。 The present invention has been made in view of the problems in the prior art described above, and in a magnetic sensor using a tunnel magnetoresistive element, achieves high sensitivity of the tunnel magnetoresistive element and measures magnetism with high accuracy. It is an object of the present invention to provide a magnetic sensor capable of performing the above and a manufacturing method thereof.
　以上の課題を解決するための請求項１記載の発明は、磁化の向きが固定された強磁性金属磁化固定層、外部からの磁界の影響を受けて磁化の向きが変化する強磁性金属磁化自由層、及び、前記強磁性金属磁化固定層と前記強磁性金属磁化自由層との間に配置された絶縁層を有し、前記強磁性金属磁化固定層の磁化の向きと前記強磁性金属磁化自由層の磁化の向きとの角度差に従ってトンネル効果により前記絶縁層の抵抗を変化させるトンネル磁気抵抗素子を含む磁気センサーにおいて、
　前記強磁性金属磁化自由層は、アモルファス強磁性体を含むことを特徴とする磁気センサーである。
　ここで、「ねじれの位置」とは、空間内の２直線が平行でなく、かつ、交わっていない位置関係、すなわち、同一平面に存在できない２直線の位置関係をいう。ねじれの位置にある２直線に直交する直線を「ねじれの軸」といい、ねじれの軸まわりの一方の直線に対する他方の直線の相対角を「ねじれの角」という。 The invention described in claim 1 for solving the above-mentioned problems is a ferromagnetic metal magnetization fixed layer in which the magnetization direction is fixed, and the ferromagnetic metal magnetization free in which the magnetization direction changes under the influence of an external magnetic field. And an insulating layer disposed between the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal magnetization free layer, the magnetization direction of the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal magnetization free In a magnetic sensor including a tunnel magnetoresistive element that changes a resistance of the insulating layer by a tunnel effect according to an angle difference with a magnetization direction of the layer,
The ferromagnetic metal magnetization free layer is a magnetic sensor including an amorphous ferromagnet.
Here, the “twisted position” refers to a positional relationship in which two straight lines in the space are not parallel and do not intersect, that is, a positional relationship between two straight lines that cannot exist on the same plane. A straight line perpendicular to the two straight lines at the position of twist is called “twist axis”, and the relative angle of the other straight line to one straight line around the twist axis is called “twist angle”.
　請求項２記載の発明は、ゼロ磁界での前記強磁性金属磁化自由層の容易磁化軸は、前記強磁性金属磁化固定層の容易磁化軸に対してねじれの位置にあることを特徴とする請求項１に記載の磁気センサーである。 The invention according to claim 2 is characterized in that the easy magnetization axis of the ferromagnetic metal magnetization free layer in a zero magnetic field is in a twisted position with respect to the easy magnetization axis of the ferromagnetic metal magnetization fixed layer. Item 2. The magnetic sensor according to Item 1.
　請求項３記載の発明は、前記強磁性金属磁化自由層は、第１の強磁性体と、前記絶縁層に接合する第２の強磁性体と、前記第１の強磁性体と前記第２の強磁性体との間に挟まれて存在する極薄非磁性体金属層とを備え、前記第１の強磁性体の磁化の向きと前記第２の強磁性体の磁化の向きとが、平行になる交換結合力を有する平行結合膜構造体、又は反平行になる交換結合力を有する反平行結合膜構造体であり、
　前記強磁性金属磁化自由層の前記第１の強磁性体は、アモルファス強磁性体からなることを特徴とする請求項１または請求項２に記載の磁気センサーである。 According to a third aspect of the present invention, the ferromagnetic metal magnetization free layer includes a first ferromagnetic material, a second ferromagnetic material joined to the insulating layer, the first ferromagnetic material, and the second ferromagnetic material. An ultrathin nonmagnetic metal layer sandwiched between the first ferromagnetic material and the second ferromagnetic material, wherein the magnetization direction of the first ferromagnetic material and the magnetization direction of the second ferromagnetic material are: A parallel coupling membrane structure having an exchange coupling force to be parallel, or an antiparallel coupling membrane structure having an exchange coupling force to be antiparallel,
3. The magnetic sensor according to claim 1, wherein the first ferromagnetic body of the ferromagnetic metal magnetization free layer is made of an amorphous ferromagnetic body.
　請求項４記載の発明は、前記強磁性金属磁化自由層は、前記第２の強磁性体がＣｏＦｅＢからなり、前記極薄非磁性体金属層がＲｕからなる反平行結合膜構造体であることを特徴とする請求項３に記載の磁気センサーである。 According to a fourth aspect of the present invention, the ferromagnetic metal magnetization free layer is an antiparallel coupling film structure in which the second ferromagnetic material is made of CoFeB and the ultrathin nonmagnetic metal layer is made of Ru. The magnetic sensor according to claim 3.
　請求項５記載の発明は、前記アモルファス強磁性体からなる前記強磁性金属磁化自由層の前記第１の強磁性体は、１０ｎｍから１００ｎｍの膜厚であることを特徴とする請求項３に記載の磁気センサーである。 The invention according to claim 5 is characterized in that the first ferromagnetic material of the ferromagnetic metal magnetization free layer made of the amorphous ferromagnetic material has a thickness of 10 nm to 100 nm. Magnetic sensor.
　請求項６記載の発明は、前記極薄非磁性体金属層は、０．４ｎｍから１．５ｎｍの膜厚であることを特徴とする請求項３に記載の磁気センサーである。 The invention according to claim 6 is the magnetic sensor according to claim 3, wherein the ultra-thin non-magnetic metal layer has a thickness of 0.4 nm to 1.5 nm.
　請求項７記載の発明は、ゼロ磁界での前記強磁性金属磁化自由層の容易磁化軸と、前記強磁性金属磁化固定層の容易磁化軸とのねじれの角は、４５度から１３５度であることを特徴とする請求項２から請求項６のうちいずれか一に記載の磁気センサーである。 According to a seventh aspect of the present invention, the angle of twist between the easy magnetization axis of the ferromagnetic metal magnetization free layer and the easy magnetization axis of the ferromagnetic metal magnetization fixed layer in a zero magnetic field is 45 degrees to 135 degrees. It is a magnetic sensor as described in any one of Claim 2-6 characterized by the above-mentioned.
　請求項８記載の発明は、磁化の向きが固定された強磁性金属磁化固定層、外部からの磁界の影響を受けて磁化の向きが変化する強磁性金属磁化自由層、及び、前記強磁性金属磁化固定層と前記強磁性金属磁化自由層との間に配置された絶縁層を有し、前記強磁性金属磁化固定層の磁化の向きと前記強磁性金属磁化自由層の磁化の向きとの角度差に従ってトンネル効果により前記絶縁層の抵抗を変化させるトンネル磁気抵抗素子を含む磁気センサーを製造する方法であって、
　熱処理を行う前の、前記強磁性金属磁化固定層および前記強磁性金属磁化自由層に対して、外部磁界を印加しながら第１の温度で第１の熱処理を行い、該第１の温度よりも低い第２の温度でかつ前記第１の熱処理とは向きを異ならせて外部磁界を印加しながら第２の熱処理を行うことで、熱処理後のゼロ磁界での前記強磁性金属磁化自由層の容易磁化軸を、前記強磁性金属磁化固定層の容易磁化軸に対してねじれの位置にするにあたり、
　前記強磁性金属磁化自由層がアモルファス強磁性体を含み、前記第１の温度を３００℃から５００℃の範囲とし、前記第２の温度を２００℃から３５０℃の範囲とすることを特徴とする磁気センサーの製造方法である。 The invention according to claim 8 is a ferromagnetic metal magnetization fixed layer whose magnetization direction is fixed, a ferromagnetic metal magnetization free layer whose magnetization direction changes under the influence of an external magnetic field, and the ferromagnetic metal An angle between a magnetization direction of the ferromagnetic metal magnetization fixed layer and a magnetization direction of the ferromagnetic metal magnetization free layer having an insulating layer disposed between the magnetization fixed layer and the ferromagnetic metal magnetization free layer; A method of manufacturing a magnetic sensor including a tunnel magnetoresistive element that changes a resistance of the insulating layer by a tunnel effect according to a difference,
A first heat treatment is performed at a first temperature while applying an external magnetic field to the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal magnetization free layer before the heat treatment. By performing the second heat treatment while applying an external magnetic field at a low second temperature and in a different direction from the first heat treatment, the ferromagnetic metal magnetization free layer can be easily formed in a zero magnetic field after the heat treatment. In setting the magnetization axis to a position twisted with respect to the easy magnetization axis of the ferromagnetic metal magnetization fixed layer,
The ferromagnetic metal magnetization free layer includes an amorphous ferromagnet, wherein the first temperature is in a range of 300 ° C. to 500 ° C., and the second temperature is in a range of 200 ° C. to 350 ° C. It is a manufacturing method of a magnetic sensor.
　アモルファス強磁性体は、磁気異方性が小さく軟磁性を示し、強磁性金属磁化自由層に適用されることによって、強磁性金属磁化自由層は外部からの磁界の影響を受けて磁化の向きが容易に変化する性質、すなわち、感度が向上する。
　また、アモルファス強磁性体は、より高温での熱処理においてもアモルファス状態を維持し耐えることができるから、強磁性金属磁化自由層及び強磁性金属磁化固定層に誘導磁気異方性を付加する第１の熱処理の第１の温度を、十分に高い温度に設定することができ、これら両層とその間の絶縁層からなる強磁性トンネル接合（ＭＴＪ）を、良質な状態に形成して高感度化を図ることができる。
　したがって、本発明によれば、強磁性金属磁化自由層がアモルファス強磁性体を含むため、トンネル磁気抵抗素子の高感度化を達成し、高精度に磁気を計測することができる。 Amorphous ferromagnets have small magnetic anisotropy and soft magnetism. When applied to a ferromagnetic metal magnetization free layer, the ferromagnetic metal magnetization free layer is affected by an external magnetic field and has a magnetization direction. The property that changes easily, that is, the sensitivity is improved.
In addition, since the amorphous ferromagnet can maintain and withstand the amorphous state even in the heat treatment at a higher temperature, the first ferromagnetic magnetic anisotropy is added to the ferromagnetic metal magnetization free layer and the ferromagnetic metal magnetization fixed layer. The first temperature of the heat treatment can be set to a sufficiently high temperature, and the ferromagnetic tunnel junction (MTJ) composed of both layers and the insulating layer therebetween is formed in a high quality state to increase the sensitivity. Can be planned.
Therefore, according to the present invention, since the ferromagnetic metal magnetization free layer includes the amorphous ferromagnet, it is possible to achieve high sensitivity of the tunnel magnetoresistive element and to measure magnetism with high accuracy.
本発明の一実施形態に係る磁気センサーの構成図である。It is a block diagram of the magnetic sensor which concerns on one Embodiment of this invention. 本発明の一実施形態に係るトンネル磁気抵抗素子の模式的斜視図であり、絶縁層を省略して描いている。1 is a schematic perspective view of a tunnel magnetoresistive element according to an embodiment of the present invention, in which an insulating layer is omitted. 本発明の一実施形態に係るトンネル磁気抵抗素子の模式的斜視図であり、絶縁層を省略して描いている。1 is a schematic perspective view of a tunnel magnetoresistive element according to an embodiment of the present invention, in which an insulating layer is omitted. 本発明の一実施形態に係るトンネル磁気抵抗素子の磁場中熱処理工程における炉中温度の変遷を示すグラフである。It is a graph which shows transition of the temperature in a furnace in the heat treatment process in a magnetic field of the tunnel magnetoresistive element concerning one embodiment of the present invention. 予備実験におけるアモルファス強磁性体膜を含む積層構造の断面模式図である。It is a cross-sectional schematic diagram of a laminated structure including an amorphous ferromagnetic film in a preliminary experiment. 予備実験に係り、アモルファス強磁性体膜の熱処理前における磁化Ｍ－磁場Ｈ曲線である。It is a magnetization M-magnetic field H curve before the heat treatment of the amorphous ferromagnetic film in connection with the preliminary experiment. 予備実験に係り、アモルファス強磁性体膜の熱処理後における磁化Ｍ－磁場Ｈ曲線である。It is a magnetization M-magnetic field H curve after the heat treatment of the amorphous ferromagnetic film in connection with the preliminary experiment. 予備実験に係り、Ｘ線結晶構造解析（ＸＲＤ）により測定したＸ線回折スペクトルである。It is an X-ray diffraction spectrum measured by X-ray crystal structure analysis (XRD) in connection with a preliminary experiment. 本発明の実施例に係り、第１の熱処理の熱処理温度（第１の温度Ｔｆ）の違いによるＴＭＲ比の変化を示すグラフである。強磁性金属磁化自由層が平行結合膜構造体であるものに関する。It is a graph which shows the change of TMR ratio by the difference in the heat processing temperature (1st temperature Tf) of 1st heat processing concerning the Example of this invention. The present invention relates to a ferromagnetic metal magnetization free layer having a parallel coupling film structure. 本発明の実施例に係り、第１の熱処理の熱処理温度（第１の温度Ｔｆ）の違いによるＴＭＲ比の変化を示すグラフである。強磁性金属磁化自由層が反平行結合膜構造体であるものに関する。It is a graph which shows the change of TMR ratio by the difference in the heat processing temperature (1st temperature Tf) of 1st heat processing concerning the Example of this invention. The present invention relates to a ferromagnetic metal magnetization free layer having an antiparallel coupling film structure. 本発明の実施例に係り、外部磁界（Ｈ（Ｏｅ）、横軸）に対するＴＭＲ素子の抵抗の変化率（ＴＭＲ比（％）、縦軸）を示したグラフである。4 is a graph showing a rate of change in resistance of a TMR element (TMR ratio (%), vertical axis) with respect to an external magnetic field (H (Oe), horizontal axis) according to an example of the present invention. 本発明の実施例に係り、外部磁界（Ｈ（Ｏｅ）、横軸）に対するＴＭＲ素子の抵抗の変化率（ＴＭＲ比（％）、縦軸）を示したグラフである。4 is a graph showing a rate of change in resistance of a TMR element (TMR ratio (%), vertical axis) with respect to an external magnetic field (H (Oe), horizontal axis) according to an example of the present invention. 本発明の実施例に係り、外部磁界（Ｈ（Ｏｅ）、横軸）に対するＴＭＲ素子の抵抗の変化率（ＴＭＲ比（％）、縦軸）を示したグラフである。4 is a graph showing a rate of change in resistance of a TMR element (TMR ratio (%), vertical axis) with respect to an external magnetic field (H (Oe), horizontal axis) according to an example of the present invention.
　以下に本発明の一実施形態につき図面を参照して説明する。以下は本発明の一実施形態であって本発明を限定するものではない。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.
　本実施形態の磁気センサーは、代表的な例としては、人の頭蓋から発せられる磁界を計測して脳磁図を得る生体磁気計測に利用されるものであり、必要な本数の磁気センサーが組み込まれ各種の生体磁気計測システムが構成され、生体から発せられる磁界の計測が実施される。また、常温で使用可能で、小型軽薄化、高密度化等が可能なトンネル磁気抵抗素子の特性を活かして、生体磁気に限らず、様々な磁気発生源からの磁気を２次元的又は３次元的に計測することに利用できる。 As a typical example, the magnetic sensor of the present embodiment is used for biomagnetic measurement in which a magnetoencephalogram is obtained by measuring a magnetic field emitted from a human skull, and a necessary number of magnetic sensors are incorporated. Various biomagnetism measurement systems are configured to measure a magnetic field emitted from a living body. In addition, by utilizing the characteristics of tunneling magnetoresistive elements that can be used at room temperature and can be reduced in size, weight, thickness, density, etc., the magnetism from various magnetic sources is not limited to biomagnetism. It can be used to measure automatically.
　図１に示すように本磁気センサー１は、トンネル磁気抵抗素子（以下「ＴＭＲ素子」という。）１０を含んで構成される。
　図１に示すように本磁気センサー１は、基板２上に、下部電極層３、強磁性金属磁化自由層４、絶縁層５、強磁性金属磁化固定層６、固定化促進層７、上部電極層８が順次積層された積層構造を有する。
　ＴＭＲ素子１０は、強磁性金属磁化固定層６の磁化の向きと強磁性金属磁化自由層４の磁化の向きとの角度差に従ってトンネル効果により絶縁層５の抵抗を変化させる。
　上部電極層８と下部電極層３との間には、電流を入力するための電源１１と定抵抗１２とが直列に接続され、さらに絶縁層５の抵抗値の変化を電圧値の変化として検知する電圧計１３に接続されて本磁気センサー１は実装される。なお、ＴＭＲ素子１０に対して電圧を印加し、ＴＭＲ素子１０の絶縁層５に流れる電流を検出することで絶縁層５の抵抗値の変化を検出するようにしても構わない。 As shown in FIG. 1, the magnetic sensor 1 includes a tunnel magnetoresistive element (hereinafter referred to as “TMR element”) 10.
As shown in FIG. 1, the magnetic sensor 1 includes a lower electrode layer 3, a ferromagnetic metal magnetization free layer 4, an insulating layer 5, a ferromagnetic metal magnetization fixed layer 6, an immobilization promoting layer 7, an upper electrode on a substrate 2. It has a laminated structure in which the layers 8 are sequentially laminated.
The TMR element 10 changes the resistance of the insulating layer 5 by the tunnel effect according to the angle difference between the magnetization direction of the ferromagnetic metal magnetization fixed layer 6 and the magnetization direction of the ferromagnetic metal magnetization free layer 4.
A power supply 11 for inputting current and a constant resistance 12 are connected in series between the upper electrode layer 8 and the lower electrode layer 3, and a change in resistance value of the insulating layer 5 is detected as a change in voltage value. The magnetic sensor 1 is mounted by being connected to the voltmeter 13. Note that a change in the resistance value of the insulating layer 5 may be detected by applying a voltage to the TMR element 10 and detecting a current flowing through the insulating layer 5 of the TMR element 10.
　基板２としては、各層の形成に耐え得るものであれば特に材質に限定はないが、成膜時や熱処理等に耐え得る耐熱性と絶縁性とを兼ね備えたものが好ましい。また、磁束の吸い込みを防止するために非磁性であり、表面が比較的滑らかに形成されるものであることが好ましい。このような観点からは、例えば、Ｓｉ、ＳｉＯ２等が使用できる。 The material of the substrate 2 is not particularly limited as long as it can withstand the formation of each layer, but a substrate having both heat resistance and insulation that can withstand film formation and heat treatment is preferable. Moreover, it is preferable that it is non-magnetic to prevent the magnetic flux from being sucked and the surface is formed relatively smoothly. From such a viewpoint, for example, Si, SiO 2 or the like can be used.
　下部電極層３は、３つの層３１，３２，３３からなる。層３１は、基板２の粗さを整えるためのものであり、例えば、Ｔａが使用できる。層３１の層厚は２ｎｍ～１０ｎｍ程度とすることが好ましい。層３２としてはＲｕ、層３３としてはＴａが使用できる。下部電極層３を例えばＴａのみなど１つの層で構成して実施することもできる。 The lower electrode layer 3 is composed of three layers 31, 32 and 33. The layer 31 is for adjusting the roughness of the substrate 2, and for example, Ta can be used. The layer thickness of the layer 31 is preferably about 2 nm to 10 nm. Ru can be used as the layer 32 and Ta can be used as the layer 33. For example, the lower electrode layer 3 may be formed of one layer such as Ta alone.
　強磁性金属磁化自由層４は、外部からの磁束の影響を受けて磁化の向きが変化する強磁性金属磁化層で、第１の強磁性体層４１と、極薄非磁性体金属層４２と、第２の強磁性体層４３とからなる。
　第１の強磁性体層４１は、アモルファス強磁性体からなる。アモルファス強磁性体は、磁気異方性が小さく軟磁性を示し、強磁性金属磁化自由層４に適用されることによって、強磁性金属磁化自由層４は外部からの磁界の影響を受けて磁化の向きが容易に変化する性質、すなわち、感度が向上する。第１の強磁性体層４１に適用されるアモルファス強磁性体としては、例えば、ＣｏＦｅＳｉＢや、ＣｏＮｂＺｒ、ＣｏＺｒＴａ、ＣｏＨｆＴａ等が使用できる。第１の強磁性体層４１の層厚は１０ｎｍから１００ｎｍであることが好ましい。
　極薄非磁性体金属層４２は、第１の強磁性体層４１と第２の強磁性体層４３とを磁気的に結合させるとともに、後者を前者の構造から切り離すためのものであり、結晶構造を有さない薄膜層を用いるのが望ましい。具体的な材料の例としてはＲｕや、Ｔａが挙げられる。Ｒｕとするとき極薄非磁性体金属層４２の層厚は０．４から１．５ｎｍであることが好ましく、より好ましくは、０．８ｎｍから１．３ｎｍである。
　第２の強磁性体層４３としては、各種のものが使用可能であるが、代表的なものとして、Ｃｏ４０Ｆｅ４０Ｂ２０をアモルファス構造から熱処理して強磁性を発現させたものが使用できる。この層の結晶構造は例えば体心立方晶である。Ｆｅリッチの材料、例えば、Ｃｏ１６Ｆｅ６４Ｂ２０を用いることもできる。第２の強磁性体層４３の層厚は１～１０ｎｍ程度が好ましい。第２の強磁性体層４３が絶縁層５の下面に接合する。
　強磁性金属磁化自由層４は、以上のように第１の強磁性体層４１と、第２の強磁性体層４３と、これらの間に挟まれて存在する極薄非磁性体金属層４２とを備える。第２の強磁性体４３がＣｏＦｅＢからなり、極薄非磁性体金属層４２がＲｕからなるとき、強磁性金属磁化自由層４は、第１の強磁性体層４１の磁化の向きと第２の強磁性体層４３の磁化の向きとが反平行になる交換結合力を有する反平行結合膜構造体を構成する。また、第２の強磁性体４３がＣｏＦｅＢからなり、極薄非磁性体金属層４２がＴａからなるとき、強磁性金属磁化自由層４は、第１の強磁性体層４１の磁化の向きと第２の強磁性体層４３の磁化の向きとが平行になる交換結合力を有する平行結合膜構造体を構成する。ここで「平行」「反平行」とは、磁化の向きが実質的に平行で、かつ、前者にあっては同方向、後者にあっては逆方向を向いていることを意味し、実質的に磁化の向きが平行とみなせる範囲（例えば、前後へ１０度傾いた範囲）にある場合も含む。 The ferromagnetic metal magnetization free layer 4 is a ferromagnetic metal magnetization layer whose magnetization direction changes under the influence of an external magnetic flux, and includes a first ferromagnetic layer 41, an ultrathin nonmagnetic metal layer 42, and the like. And the second ferromagnetic layer 43.
The first ferromagnetic layer 41 is made of an amorphous ferromagnetic material. An amorphous ferromagnet has a small magnetic anisotropy and exhibits soft magnetism. By being applied to the ferromagnetic metal magnetization free layer 4, the ferromagnetic metal magnetization free layer 4 is affected by an external magnetic field and is magnetized. The property of easily changing the orientation, that is, the sensitivity is improved. As the amorphous ferromagnetic material applied to the first ferromagnetic material layer 41, for example, CoFeSiB, CoNbZr, CoZrTa, CoHfTa, or the like can be used. The thickness of the first ferromagnetic layer 41 is preferably 10 nm to 100 nm.
The ultrathin nonmagnetic metal layer 42 is for magnetically coupling the first ferromagnetic layer 41 and the second ferromagnetic layer 43 and for separating the latter from the former structure. It is desirable to use a thin film layer having no structure. Specific examples of the material include Ru and Ta. When Ru is used, the thickness of the ultrathin nonmagnetic metal layer 42 is preferably 0.4 to 1.5 nm, and more preferably 0.8 nm to 1.3 nm.
As the second ferromagnetic layer 43, various types can be used. As a typical example, a layer obtained by heat-treating Co40Fe40B20 from an amorphous structure to exhibit ferromagnetism can be used. The crystal structure of this layer is, for example, a body-centered cubic crystal. An Fe-rich material such as Co16Fe64B20 can also be used. The thickness of the second ferromagnetic layer 43 is preferably about 1 to 10 nm. The second ferromagnetic layer 43 is bonded to the lower surface of the insulating layer 5.
As described above, the ferromagnetic metal magnetization free layer 4 includes the first ferromagnetic layer 41, the second ferromagnetic layer 43, and the ultrathin nonmagnetic metal layer 42 sandwiched between them. With. When the second ferromagnetic body 43 is made of CoFeB and the ultrathin nonmagnetic metal layer 42 is made of Ru, the ferromagnetic metal magnetization free layer 4 has a second direction of magnetization of the first ferromagnetic layer 41 and the second direction. An antiparallel coupling film structure having an exchange coupling force in which the magnetization direction of the ferromagnetic layer 43 is antiparallel is formed. When the second ferromagnetic material 43 is made of CoFeB and the ultrathin nonmagnetic metal layer 42 is made of Ta, the ferromagnetic metal magnetization free layer 4 has the magnetization direction of the first ferromagnetic material layer 41 and A parallel coupling film structure having an exchange coupling force in which the magnetization direction of the second ferromagnetic layer 43 is parallel is configured. Here, “parallel” and “anti-parallel” mean that the directions of magnetization are substantially parallel and in the same direction in the former and in the opposite direction in the latter. Includes a case in which the direction of magnetization is in a range that can be regarded as parallel (for example, a range tilted 10 degrees forward and backward).
　絶縁層５は、強磁性金属磁化固定層６と強磁性金属磁化自由層４との間に配置される。絶縁層５としては、各種の絶縁材料を用いることができ、例えば、ＭｇＯ、ＡｌＯｘ等が使用できる。素子の感度を向上させるという観点からはＭｇＯが好ましく、特に、生体磁気信号のような微弱磁界をトンネル磁気抵抗素子で検出するためには、絶縁層５としてＭｇＯ膜を用いることが好ましい。絶縁層５の層厚は、１ｎｍ～１０ｎｍ程度にすることが望ましい。 The insulating layer 5 is disposed between the ferromagnetic metal magnetization fixed layer 6 and the ferromagnetic metal magnetization free layer 4. As the insulating layer 5, various insulating materials can be used. For example, MgO, AlOx, or the like can be used. MgO is preferable from the viewpoint of improving the sensitivity of the element, and in particular, an MgO film is preferably used as the insulating layer 5 in order to detect a weak magnetic field such as a biomagnetic signal with a tunnel magnetoresistive element. The thickness of the insulating layer 5 is desirably about 1 nm to 10 nm.
　強磁性金属磁化固定層６は、磁化の向きが固定された強磁性金属磁化層で、第１の強磁性体層６１と、極薄非磁性体金属層６２と、第２の強磁性体層６３とからなる。
　第１の強磁性体層６１としては、自由層４の第２の強磁性体層４３と同様のもの、例えば、Ｃｏ４０Ｆｅ４０Ｂ２０が使用できる。第１の強磁性体層６１の層厚は１～１０ｎｍ程度が好ましい。第１の強磁性体層６１は絶縁層５の上面に接合する。
　極薄非磁性体金属層６２は、第１の強磁性体層６１と第２の強磁性体層６３とを磁気的に結合させるとともに、後者を前者の結晶構造から切り離すためのものであり、結晶構造を有さない薄膜層を用いるのが望ましい。具体的な材料の例としてはＲｕが挙げられる。極薄非磁性体金属層６２の層厚は０．５～１ｎｍ程度とすることが好ましい。
　第２の強磁性体層６３としては、例えば、ＣｏＦｅが使用できる。ＣｏとＦｅの組成比は任意に設定できるが、典型的には、Ｃｏ：Ｆｅ＝７５：２５又はＣｏ：Ｆｅ＝５０：５０とすることができる。第２の強磁性体層６３の結晶構造は例えば面心立方晶である。第２の強磁性体層６３の層厚としては、０．５ｎｍ～５ｎｍ程度とすることが好ましい。
　強磁性金属磁化固定層６は、以上のように第１の強磁性体層６１と、第２の強磁性体層６３と、これらの間に挟まれて存在する極薄非磁性体金属層６２とを備え、第１の強磁性体層６１の磁化の向きと第２の強磁性体層６３の磁化の向きとが反平行になる交換結合力を有する反平行結合膜構造体を構成する。 The ferromagnetic metal magnetization fixed layer 6 is a ferromagnetic metal magnetization layer whose magnetization direction is fixed. The first ferromagnetic layer 61, the ultrathin nonmagnetic metal layer 62, and the second ferromagnetic layer. 63.
As the first ferromagnetic layer 61, the same material as the second ferromagnetic layer 43 of the free layer 4, for example, Co40Fe40B20 can be used. The thickness of the first ferromagnetic layer 61 is preferably about 1 to 10 nm. The first ferromagnetic layer 61 is bonded to the upper surface of the insulating layer 5.
The ultra-thin non-magnetic metal layer 62 is for magnetically coupling the first ferromagnetic layer 61 and the second ferromagnetic layer 63 and separating the latter from the former crystal structure. It is desirable to use a thin film layer having no crystal structure. Specific examples of the material include Ru. The layer thickness of the ultrathin nonmagnetic metal layer 62 is preferably about 0.5 to 1 nm.
As the second ferromagnetic layer 63, for example, CoFe can be used. The composition ratio of Co and Fe can be arbitrarily set, but typically, Co: Fe = 75: 25 or Co: Fe = 50: 50 can be set. The crystal structure of the second ferromagnetic layer 63 is, for example, a face centered cubic crystal. The layer thickness of the second ferromagnetic layer 63 is preferably about 0.5 nm to 5 nm.
As described above, the ferromagnetic metal magnetization fixed layer 6 includes the first ferromagnetic layer 61, the second ferromagnetic layer 63, and the ultrathin nonmagnetic metal layer 62 that is sandwiched therebetween. And an antiparallel coupling film structure having an exchange coupling force in which the magnetization direction of the first ferromagnetic layer 61 and the magnetization direction of the second ferromagnetic layer 63 are antiparallel.
　固定化促進層７は、第２の強磁性体層６３の固定化を促進するためのものであり、ＩｒＭｎ、プラチナマンガンなどの反強磁性膜が好適に用いられる。固定化促進層７の層厚は５ｎｍ～２０ｎｍ程度とすることが好ましい。 The immobilization promoting layer 7 is for promoting the immobilization of the second ferromagnetic layer 63, and an antiferromagnetic film such as IrMn or platinum manganese is preferably used. The thickness of the immobilization promoting layer 7 is preferably about 5 nm to 20 nm.
　上部電極層８は、２つの層８１，８２からなる。層８１は、層８２の下地層で固定化促進層７の粗さを整えるためのものであり、例えば、Ｔａが使用できる。層８１の層厚は２ｎｍ～１０ｎｍ程度とすることが好ましい。層８２は電極が接続される上層であり、例えば、Ａｕが使用できる。層８２の層厚は２０ｎｍ～４０ｎｍ程度とすることが好ましい。 The upper electrode layer 8 is composed of two layers 81 and 82. The layer 81 is a base layer of the layer 82 for adjusting the roughness of the immobilization promoting layer 7, and for example, Ta can be used. The layer 81 preferably has a thickness of about 2 nm to 10 nm. The layer 82 is an upper layer to which an electrode is connected, and for example, Au can be used. The layer 82 preferably has a thickness of about 20 nm to 40 nm.
　各層は、例えば、マグネトロンスパッタリング法により形成することができる。また、所望の結晶構造を得る等の目的のために、必要に応じて熱処理を施すとよい。本実施形態にあっては、図２Ａ及び図２Ｂに示すように、ゼロ磁界での強磁性金属磁化自由層４の容易磁化軸４ａは、強磁性金属磁化固定層６の容易磁化軸６ａに対してねじれの位置にある。このような関係の容易磁化軸４ａ，６ａを得るために、各層を積層した基板２を炉に納めるとともに磁界中に置き、図３に示すように温度条件の異なる２回の熱処理を行う。
　まず、第１の熱処理を行うことで、強磁性金属磁化自由層４及び強磁性金属磁化固定層６に誘導磁気異方性が付加され、強磁性金属磁化自由層４の容易磁化軸４ａ及び強磁性金属磁化固定層６の容易磁化軸６ａが形成される。但し、容易磁化軸４ａと容易磁化軸６ａとが同方向を向いている。第２の熱処理の温度変遷グラフＡ２における頂点温度（第２の温度）は、第１の熱処理の温度変遷グラフＡ１における頂点温度（第１の温度）より低く（好適には１０℃以上低く）、第１の熱処理の後、好ましくは室温付近まで冷却した後、第２の熱処理を行うことで強磁性金属磁化固定層６の容易磁化軸６ａが容易磁化軸４ａに対してねじれの位置に形成される。容易磁化軸４ａは、第１の熱処理時の磁界方向に沿って形成される。容易磁化軸６ａは、第２の熱処理時の磁界方向に沿って形成される。したがって、第１の熱処理時の磁界方向に対し第２の熱処理時の磁界方向を変えることで容易磁化軸６ａを容易磁化軸４ａに対してねじれの位置にすることができる。第１の熱処理時の磁界方向及び第２の熱処理時の磁界方向は層に平行である。したがって、基板２上の積層方向の軸（＝基板２に垂直な軸）まわりに磁界方向を回転させることで、容易磁化軸６ａを容易磁化軸４ａに対してねじれの位置にすることができる。熱処理時間に特に制限はなく、例えば１０分～２時間程度行えばよく、また、第１の熱処理よりも第２の熱処理の時間を短くすることが好ましい。熱処理の際の磁界にも特に制限はなく、例えば０．０１～２［Ｔ］の範囲で行えばよく、また、第１の熱処理よりも第２の熱処理における外部磁界を小さくすることが好ましい。
　第１の強磁性体層４１に適用されるアモルファス強磁性体は、より高温での熱処理においてもアモルファス状態を維持し耐えることができる。そのため、強磁性金属磁化自由層４及び強磁性金属磁化固定層６に誘導磁気異方性を付加する第１の熱処理の第１の温度を、十分に高い温度に設定することができ、これら両層４，６とその間の絶縁層５からなる強磁性トンネル接合（ＭＴＪ）を、良質な状態に形成して高感度化を図ることができる。
　以上を踏まえ、第１の温度を３００℃から５００℃の範囲とし、第２の温度を２００℃から３５０℃の範囲とすることが好ましい。より好ましくは、第１の温度を３５０℃から３８０℃の範囲とする。第２の温度を２５０℃から３５０℃の範囲とする。 Each layer can be formed by, for example, a magnetron sputtering method. In addition, for the purpose of obtaining a desired crystal structure, heat treatment may be performed as necessary. In the present embodiment, as shown in FIGS. 2A and 2B, the easy magnetization axis 4 a of the ferromagnetic metal magnetization free layer 4 in the zero magnetic field is relative to the easy magnetization axis 6 a of the ferromagnetic metal magnetization fixed layer 6. In the twisted position. In order to obtain the easy magnetization axes 4a and 6a having such a relationship, the substrate 2 on which the respective layers are stacked is placed in a furnace and placed in a magnetic field, and two heat treatments with different temperature conditions are performed as shown in FIG.
First, by performing the first heat treatment, induced magnetic anisotropy is added to the ferromagnetic metal magnetization free layer 4 and the ferromagnetic metal magnetization fixed layer 6, and the easy magnetization axis 4a and strong magnetization of the ferromagnetic metal magnetization free layer 4 are increased. The easy magnetization axis 6a of the magnetic metal magnetization fixed layer 6 is formed. However, the easy magnetization axis 4a and the easy magnetization axis 6a are in the same direction. The vertex temperature (second temperature) in the temperature transition graph A2 of the second heat treatment is lower than the vertex temperature (first temperature) in the temperature transition graph A1 of the first heat treatment (preferably lower by 10 ° C. or more), After the first heat treatment, preferably after cooling to near room temperature, the second heat treatment is performed, whereby the easy magnetization axis 6a of the ferromagnetic metal magnetization fixed layer 6 is formed at a twisted position with respect to the easy magnetization axis 4a. The The easy magnetization axis 4a is formed along the magnetic field direction during the first heat treatment. The easy magnetization axis 6a is formed along the magnetic field direction during the second heat treatment. Therefore, by changing the magnetic field direction during the second heat treatment with respect to the magnetic field direction during the first heat treatment, the easy magnetization axis 6a can be twisted with respect to the easy magnetization axis 4a. The magnetic field direction during the first heat treatment and the magnetic field direction during the second heat treatment are parallel to the layers. Therefore, the easy magnetization axis 6a can be in a twisted position with respect to the easy magnetization axis 4a by rotating the magnetic field direction around an axis in the stacking direction on the substrate 2 (= an axis perpendicular to the substrate 2). There is no particular limitation on the heat treatment time, and it may be performed, for example, for about 10 minutes to 2 hours, and it is preferable to make the second heat treatment time shorter than the first heat treatment. There is no particular limitation on the magnetic field in the heat treatment, and the magnetic field may be, for example, in the range of 0.01 to 2 [T]. The external magnetic field in the second heat treatment is preferably smaller than that in the first heat treatment.
The amorphous ferromagnet applied to the first ferromagnet layer 41 can maintain and withstand the amorphous state even during heat treatment at a higher temperature. Therefore, the first temperature of the first heat treatment for adding induced magnetic anisotropy to the ferromagnetic metal magnetization free layer 4 and the ferromagnetic metal magnetization fixed layer 6 can be set to a sufficiently high temperature. A ferromagnetic tunnel junction (MTJ) composed of the layers 4 and 6 and the insulating layer 5 therebetween can be formed in a high quality state to achieve high sensitivity.
Based on the above, it is preferable that the first temperature is in the range of 300 ° C. to 500 ° C. and the second temperature is in the range of 200 ° C. to 350 ° C. More preferably, the first temperature is in the range of 350 ° C to 380 ° C. The second temperature is in the range of 250 ° C to 350 ° C.
　図２Ａに示すように容易磁化軸４ａと容易磁化軸６ａとのねじれの角φは９０度を目標として作製すれば足りる。図２Ｂに示すように容易磁化軸４ａと容易磁化軸６ａが平行でなければ、両者の成すねじれの角φが９０度でなくても感度向上の効果はあるが、ねじれの角φは、４５度から１３５度の範囲とすることが好ましい。 As shown in FIG. 2A, it is sufficient that the twist angle φ between the easy magnetization axis 4a and the easy magnetization axis 6a is 90 degrees. As shown in FIG. 2B, if the easy magnetization axis 4a and the easy magnetization axis 6a are not parallel, the effect of improving the sensitivity is obtained even if the twist angle φ between them is not 90 degrees, but the twist angle φ is 45 It is preferable that the angle is in the range of from 135 degrees to 135 degrees.
　また、強磁性金属磁化固定層６の面積は、強磁性金属磁化自由層４の面積と等しいか、図２Ａ又は図２Ｂに示すように、強磁性金属磁化自由層４の面積に対して小さくする。強磁性金属磁化固定層６の面積を相対的に小さくすることで、固定層６から自由層４への漏れ磁界の影響が小さくなり、磁気検出の感度をさらに向上させることができる。強磁性金属磁化固定層６の面積と、強磁性金属磁化自由層４の面積との比率は、これに限るものではないが、１：１～１：１０の範囲に設定することが好ましい。 Further, the area of the ferromagnetic metal magnetization fixed layer 6 is equal to the area of the ferromagnetic metal magnetization free layer 4 or smaller than the area of the ferromagnetic metal magnetization free layer 4 as shown in FIG. 2A or 2B. . By making the area of the ferromagnetic metal magnetization fixed layer 6 relatively small, the influence of the leakage magnetic field from the fixed layer 6 to the free layer 4 is reduced, and the sensitivity of magnetic detection can be further improved. The ratio of the area of the ferromagnetic metal magnetization fixed layer 6 to the area of the ferromagnetic metal magnetization free layer 4 is not limited to this, but is preferably set in the range of 1: 1 to 1:10.
　また、図１を参照して説明したように、強磁性金属磁化自由層４及び強磁性金属磁化固定層６を含む積層体を支持する基板２から見て、強磁性金属磁化固定層６が強磁性金属磁化自由層４より上層に（すなわち、基板２からより遠い側に）形成されている。このような上下関係とすることにより、強磁性金属磁化固定層６等が積層された基板表面からの選択的エッチングにより、強磁性金属磁化固定層６の面積を、強磁性金属磁化自由層４の面積に対して小さく形成することが容易である。 Further, as described with reference to FIG. 1, the ferromagnetic metal magnetization fixed layer 6 is strong when viewed from the substrate 2 supporting the laminated body including the ferromagnetic metal magnetization free layer 4 and the ferromagnetic metal magnetization fixed layer 6. It is formed above the magnetic metal magnetization free layer 4 (that is, on the side farther from the substrate 2). By having such a vertical relationship, the area of the ferromagnetic metal magnetization fixed layer 6 is reduced by the selective etching from the substrate surface on which the ferromagnetic metal magnetization fixed layer 6 and the like are laminated. It is easy to form small with respect to the area.
　以上説明した本実施形態の磁気センサー１によれば、強磁性金属磁化自由層４の容易磁化軸４ａと強磁性体金属磁化固定層６の容易磁化軸６ａとが、ゼロ磁界で既に異なった方向に向いている状態であり、この状態から外部磁界が発生すると、強磁性金属磁化固定層６から発生する漏れ磁界などの悪影響が小さく抑えられて強磁性金属磁化自由層４の磁化が外部磁界に対して高感度に変化する。
　また本実施形態の磁気センサー１によれば、強磁性金属磁化固定層６の面積は、強磁性金属磁化自由層４の面積に対して小さいため、これによっても、固定層６から自由層４への漏れ磁界の影響が小さく抑えられる。
　さらに本実施形態の磁気センサー１によれば、強磁性金属磁化固定層６は反平行結合膜構造体であるために漏れ磁界が少なくなり、これによっても、固定層６から自由層４への漏れ磁界の影響が小さく抑えられる。
　また、強磁性金属磁化自由層４を反平行結合膜構造体とする場合、同様に漏れ磁束のない安定した磁化膜を構成することができる。
　また、強磁性金属磁化自由層４の第１の強磁性体４１がアモルファス強磁性体からなることから、トンネル磁気抵抗素子の高感度化がさらに高水準に達成される。
　以上の各技術要素の複合によって、ＴＭＲ素子の高感度を達成することができ、高精度に生体磁気を計測することができる。
　特に、ゼロ磁界近傍で高感度な生体磁気計測に好適な生体磁気センサーとすることができる。 According to the magnetic sensor 1 of the present embodiment described above, the easy magnetization axis 4a of the ferromagnetic metal magnetization free layer 4 and the easy magnetization axis 6a of the ferromagnetic metal magnetization fixed layer 6 are different from each other in a zero magnetic field. When an external magnetic field is generated from this state, adverse effects such as a leakage magnetic field generated from the ferromagnetic metal magnetization fixed layer 6 are suppressed to be small, and the magnetization of the ferromagnetic metal magnetization free layer 4 becomes an external magnetic field. On the other hand, the sensitivity changes.
In addition, according to the magnetic sensor 1 of the present embodiment, the area of the ferromagnetic metal magnetization fixed layer 6 is smaller than the area of the ferromagnetic metal magnetization free layer 4, so that also from the fixed layer 6 to the free layer 4. The influence of the leakage magnetic field can be kept small.
Furthermore, according to the magnetic sensor 1 of the present embodiment, since the ferromagnetic metal magnetization fixed layer 6 is an antiparallel coupling film structure, the leakage magnetic field is reduced, and this also causes leakage from the fixed layer 6 to the free layer 4. The influence of the magnetic field can be kept small.
When the ferromagnetic metal magnetization free layer 4 is an antiparallel coupling film structure, a stable magnetization film free from leakage magnetic flux can be similarly formed.
In addition, since the first ferromagnet 41 of the ferromagnetic metal magnetization free layer 4 is made of an amorphous ferromagnet, higher sensitivity of the tunnel magnetoresistive element can be achieved at a higher level.
By combining the above technical elements, high sensitivity of the TMR element can be achieved, and biomagnetism can be measured with high accuracy.
In particular, a biomagnetic sensor suitable for highly sensitive biomagnetic measurement in the vicinity of zero magnetic field can be obtained.
　本発明の磁気センサーに関し以下の実験を行った。第１の強磁性体層４１のアモルファス強磁性体としてＣｏＦｅＳｉＢを採用した。 The following experiment was conducted on the magnetic sensor of the present invention. CoFeSiB was adopted as the amorphous ferromagnetic material of the first ferromagnetic layer 41.
〔予備実験〕
　予備実験では、アモルファス強磁性体膜としてＣｏＦｅＳｉＢを成膜し、上記第１の熱処理を想定した熱処理を行って、Ｘ線結晶構造解析（ＸＲＤ）及び磁化特性解析（ＶＳＭ）を行った。
　図４に示すように、シリコン基板ａ１上に膜厚ｄのＣｏＦｅＳｉＢ膜ａ２をマグネトロンスパッタリング法により成膜した。成膜条件としてアルゴンガス圧を０．１Ｐａ、スパッタ電力を３０Ｗとし、膜厚ｄが１０、３０、７０、１００ｎｍの４種の試料を作製した。さらにＣｏＦｅＳｉＢ膜ａ２上に、Ｔａ層ａ３を５ｎｍ積層した。膜厚ｄを３０ｎｍとしたこの段階の試料に対し磁化特性解析（ＶＳＭ）により測定した磁化Ｍの磁場Ｈ依存性を示すＭ－Ｈ曲線を図５Ａに示す。その後、上記第１の熱処理を想定した熱処理を行う。その熱処理条件として熱処理温度を３２５℃、３５０℃、３７５℃の３通りとし、印加磁場を２００（Ｏｅ）とした。膜厚ｄを３０ｎｍとし３２５℃で熱処理した試料に対し磁化特性解析（ＶＳＭ）により測定した磁化Ｍの磁場Ｈ依存性を示すＭ－Ｈ曲線を図５Ｂに示す。図５Ｂに示されるように２Ｈｋ＝１０．４（Ｏｅ）という低い値を得た。なお、２Ｈｋは困難軸方向に磁化の向きを反転させるのに必要な磁場に相当しており、この値が低いことによって小さな外部磁場に対して大きく反応する高感度が期待できる。膜厚ｄを１０、７０、１００ｎｍとした試料についてもＨｋ＝１０（Ｏｅ）以下であった。
　成膜後熱処理前（as depo.）、及び熱処理温度３２５℃、３５０℃、３７５℃での各熱処理後の試料について、Ｘ線結晶構造解析（ＸＲＤ）により測定したＸ線回折スペクトルを図６に示す。図６の各スペクトルでピークは１つで回折角度が一致しており、Ｓｉのみの検出が示された。これにより、いずれの熱処理温度によってもＣｏＦｅＳｉＢ膜が結晶化していないこと、すなわち、アモルファスであることを確認した。 〔Preliminary experiment〕
In the preliminary experiment, CoFeSiB was formed as an amorphous ferromagnetic film, heat treatment assuming the first heat treatment was performed, and X-ray crystal structure analysis (XRD) and magnetization characteristic analysis (VSM) were performed.
As shown in FIG. 4, a CoFeSiB film a2 having a film thickness d was formed on a silicon substrate a1 by a magnetron sputtering method. As the film forming conditions, argon gas pressure was set to 0.1 Pa, sputtering power was set to 30 W, and four types of samples having a film thickness d of 10, 30, 70, and 100 nm were prepared. Further, a 5 nm Ta layer a3 was laminated on the CoFeSiB film a2. FIG. 5A shows an MH curve showing the magnetic field H dependence of the magnetization M measured by the magnetization characteristic analysis (VSM) for the sample at this stage where the film thickness d is 30 nm. Thereafter, heat treatment assuming the first heat treatment is performed. As the heat treatment conditions, there were three heat treatment temperatures of 325 ° C., 350 ° C., and 375 ° C., and the applied magnetic field was 200 (Oe). FIG. 5B shows an MH curve showing the magnetic field H dependence of the magnetization M measured by magnetization characteristic analysis (VSM) on a sample heat-treated at 325 ° C. with a film thickness d of 30 nm. As shown in FIG. 5B, a low value of 2Hk = 10.4 (Oe) was obtained. Note that 2Hk corresponds to a magnetic field necessary for reversing the magnetization direction in the direction of the hard axis, and high sensitivity can be expected to react greatly to a small external magnetic field due to the low value. Hk = 10 (Oe) or less was also obtained for samples having a film thickness d of 10, 70, and 100 nm.
FIG. 6 shows X-ray diffraction spectra measured by X-ray crystal structure analysis (XRD) for the samples after film formation, before heat treatment (as depo.), And after heat treatment at 325 ° C., 350 ° C., and 375 ° C. Show. In each spectrum of FIG. 6, there was one peak and the diffraction angles coincided, indicating that only Si was detected. This confirmed that the CoFeSiB film was not crystallized at any heat treatment temperature, that is, was amorphous.
〔本実験〕
　本実験では、上述した実施形態の磁気センサー１に従う試料を複数作製し、第１の熱処理及び第２の熱処理の熱処理温度に対する磁気抵抗特性の依存性を調べた。試料は強磁性金属磁化自由層４が平行結合膜構造体であるものと、反平行結合膜構造体であるものの２種をそれぞれ複数作製した。
　まず、試料の共通条件として、マクネトロンスパッタリング装置を用いて、シリコン基板２上に図１に示した層３１から層８２までを順次積層した。具体的には層３１としてＴａを５ｎｍ、層３２としてＲｕを１０ｎｍ、層３３としてＴａを５ｎｍ、層４１としてＣｏＦｅＳｉＢを３０ｎｍ、層４３としてＣｏＦｅＢを３ｎｍ、層５としてＭｇＯを２．５ｎｍ、層６１としてＣｏＦｅＢを３ｎｍ、層６２としてＲｕを０．８５ｎｍ、層６３としてＣｏＦｅを５ｎｍ、層７としてＩｒＭｎを１０ｎｍ、層８１としてＴａを５ｎｍ、層８２としてＡｕを３０ｎｍ積層した。強磁性金属磁化自由層４を平行結合膜構造体とするものについては層４２としてＴａを０．２ｎｍ、強磁性金属磁化自由層４を反平行結合膜構造体とするものについては層４２としてＲｕを０．８５ｎｍ積層した。膜厚は成膜速度と成膜時間から換算して求めた。
　次に、層８２の上にフォトリソプロセスでレジストパターニングをした後、層４３に達するまでＡｒイオンミリングを行うことで、強磁性金属磁化固定層６の面積と強磁性金属磁化自由層４の面積が１：３．５の比率になるように加工し、レジスト膜を除去した。
　こうして得られた試料を、第１の熱処理として外部磁場１［Ｔ］を印加しながら試料ごとに異なる温度で６０分間熱処理を行った。室温に冷却後、この試料の配置方向を変えることにより、第１の熱処理時の磁場の磁界方向とは９０度交差する磁界方向の外部磁場０．１［Ｔ］を印加しながら、第２熱処理として試料ごとに異なる温度で１５分間熱処理を行った。室温まで冷却した後、抵抗、電源、電圧計を電気的に接続し、磁気センサーとした。 [This experiment]
In this experiment, a plurality of samples according to the magnetic sensor 1 of the above-described embodiment were manufactured, and the dependence of the magnetoresistance characteristics on the heat treatment temperatures of the first heat treatment and the second heat treatment was examined. Two types of samples, one in which the ferromagnetic metal magnetization free layer 4 is a parallel coupling film structure and the other in which the ferromagnetic metal magnetization free layer 4 is an antiparallel coupling film structure, were prepared.
First, as a common condition for the samples, layers 31 to 82 shown in FIG. 1 were sequentially laminated on the silicon substrate 2 using a magnetron sputtering apparatus. Specifically, Ta is 5 nm as layer 31, Ru is 10 nm as layer 32, Ta is 5 nm as layer 33, CoFeSiB is 30 nm as layer 41, CoFeB is 3 nm as layer 43, MgO is 2.5 nm as layer 5, layer 61 CoFeB was 3 nm, Ru was 0.85 nm as the layer 62, CoFe was 5 nm as the layer 63, IrMn was 10 nm as the layer 7, Ta was 5 nm as the layer 81, and Au was 30 nm as the layer 82. For the layer having the ferromagnetic metal magnetization free layer 4 having a parallel coupling film structure, Ta is 0.2 nm as the layer 42, and for the layer having the ferromagnetic metal magnetization free layer 4 having the antiparallel coupling film structure is Ru as the layer 42. Was stacked at 0.85 nm. The film thickness was calculated from the film formation speed and the film formation time.
Next, after resist patterning is performed on the layer 82 by a photolithography process, Ar ion milling is performed until the layer 43 is reached, whereby the area of the ferromagnetic metal magnetization fixed layer 6 and the area of the ferromagnetic metal magnetization free layer 4 are increased. The resist film was removed by processing to a ratio of 1: 3.5.
The sample thus obtained was subjected to heat treatment for 60 minutes at a different temperature for each sample while applying an external magnetic field 1 [T] as the first heat treatment. After cooling to room temperature, by changing the arrangement direction of the sample, the second heat treatment is performed while applying an external magnetic field 0.1 [T] in the magnetic field direction that intersects the magnetic field direction of the first heat treatment by 90 degrees. As a result, heat treatment was performed for 15 minutes at a different temperature for each sample. After cooling to room temperature, a resistor, a power source, and a voltmeter were electrically connected to form a magnetic sensor.
　こうして得られた磁気センサーについて磁気検出性能を測定した。具体的には、ヘルムホルツコイル内に測定対象のセンサーを配置し、センサーに数μＡの定電流を流しながら、コイルの磁界を－１８００［Ｏｅ］から、＋１８００［Ｏｅ］へ、次いで－１８００［Ｏｅ］へと変化させ、センサーの出力電圧を検出することで、外部磁場に対するセンサーの抵抗変化率（ＴＭＲ比（％））を測定した。
　第１の熱処理の熱処理温度（第１の温度Ｔｆ）の違いによるＴＭＲ比の変化を図７、図８に示した。図７は、強磁性金属磁化自由層４が平行結合膜構造体であるものに関し、図８は、強磁性金属磁化自由層４が反平行結合膜構造体であるものに関する。
　強磁性金属磁化自由層４が平行結合膜構造体であるものについては、図７に示すように第１の温度Ｔｆが３５０℃のときに最大のＴＭＲ比１９９％を得た。強磁性金属磁化自由層４が反平行結合膜構造体であるものについては、図８に示すように第１の温度Ｔｆが３７５℃のときに最大のＴＭＲ比２３４％を得た。 The magnetic detection performance of the magnetic sensor thus obtained was measured. Specifically, a sensor to be measured is placed in a Helmholtz coil, and a constant current of several μA is passed through the sensor, and the magnetic field of the coil is changed from −1800 [Oe] to +1800 [Oe] and then −1800 [Oe. The sensor resistance change rate (TMR ratio (%)) with respect to the external magnetic field was measured by detecting the output voltage of the sensor.
Changes in the TMR ratio depending on the difference in the heat treatment temperature (first temperature Tf) of the first heat treatment are shown in FIGS. 7 relates to the ferromagnetic metal magnetization free layer 4 having a parallel coupling film structure, and FIG. 8 relates to the ferromagnetic metal magnetization free layer 4 having an antiparallel coupling film structure.
For the ferromagnetic metal magnetization free layer 4 having a parallel coupling film structure, a maximum TMR ratio of 199% was obtained when the first temperature Tf was 350 ° C. as shown in FIG. In the case where the ferromagnetic metal magnetization free layer 4 is an antiparallel coupling film structure, a maximum TMR ratio of 234% was obtained when the first temperature Tf was 375 ° C. as shown in FIG.
　図９Ａ、図９Ｂ及び図９Ｃは、強磁性金属磁化自由層４が反平行結合膜構造体であるものであって、第１の温度Ｔｆ）が３７５℃とされ、第２の熱処理の熱処理温度（第２の温度Ｔｓ）がそれぞれ２８０、３００、３２０℃とされたものについて、外部磁界（Ｈ（Ｏｅ）、横軸）に対するＴＭＲ素子の抵抗の変化率（ＴＭＲ（％）、縦軸）を示したグラフである。
　これらのグラフのうち第２の温度Ｔｓを２８０、３００℃としたグラフにおいて、ゼロ磁界を含む直線的部分が現われた。この直線的部分での変化によって磁気の検出を行う。ゼロ磁界を含む直線的部分が急峻な傾きを持っていて、外部磁界の変化に対してＴＭＲ素子抵抗が大きく変化するほど高感度であるといえる。
　図９Ａに示すように第２の温度Ｔｓを２８０℃とした試料では、ＴＭＲ比＝２２８％、２Ｈｋ＝１０．４（Ｏｅ）が達成できた。ＴＭＲ比を２Ｈｋで割ることで上記の直線部分の傾きを算出し、これを感度（％／Ｏｅ）として評価することができ、この値が高い程感度が高いといえる。第２の温度Ｔｓを２８０℃とした試料では、感度３２．１（％／Ｏｅ）が達成でき、従来に例を見ない高感度が達成できた。
　図９Ｂに示すように第２の温度Ｔｓを３００℃とした試料では、ＴＭＲ比＝２２８％、２Ｈｋ＝５．７（Ｏｅ）、感度４０．０（％／Ｏｅ）が達成でき、さらに高感度が達成できた。 9A, 9B, and 9C show that the ferromagnetic metal magnetization free layer 4 is an antiparallel coupling film structure, the first temperature Tf) is 375 ° C., and the heat treatment temperature of the second heat treatment. The rate of change (TMR (%), vertical axis) of the resistance of the TMR element with respect to the external magnetic field (H (Oe), horizontal axis) for the (second temperature Ts) set to 280, 300, and 320 ° C., respectively. It is the shown graph.
Among these graphs, a linear portion including a zero magnetic field appeared in a graph in which the second temperature Ts was 280 and 300 ° C. Magnetism is detected by the change in the linear portion. It can be said that the linear portion including the zero magnetic field has a steep slope, and the sensitivity is increased as the TMR element resistance changes greatly with respect to the change in the external magnetic field.
As shown in FIG. 9A, in the sample in which the second temperature Ts was 280 ° C., the TMR ratio = 228% and 2Hk = 10.4 (Oe) could be achieved. By dividing the TMR ratio by 2Hk, the slope of the straight line portion can be calculated and evaluated as sensitivity (% / Oe). The higher this value, the higher the sensitivity. In the sample in which the second temperature Ts was 280 ° C., the sensitivity of 32.1 (% / Oe) could be achieved, and an unprecedented high sensitivity could be achieved.
As shown in FIG. 9B, the sample with the second temperature Ts of 300 ° C. can achieve TMR ratio = 228%, 2Hk = 5.7 (Oe), sensitivity 40.0 (% / Oe), and higher sensitivity. Was achieved.
　なお、以上の実施形態に拘わらず、強磁性金属磁化層に反平行結合膜構造体を適用する場合にあっては、強磁性金属磁化自由層及び強磁性金属磁化固定層のうちいずれか一方のみに反平行結合膜構造体を適用してもよく、強磁性金属磁化自由層を反平行結合膜構造体とする効果、強磁性金属磁化固定層を反平行結合膜構造体とする効果がそれぞれ得られる。
　また、強磁性金属磁化固定層の面積と、強磁性金属磁化自由層の面積との間の大小関係に条件を設けない場合にあっては、これらの層の積層における上下関係も任意であるが、固定層を上層として小面積とした方が有利であることは上述のとおりである。 Regardless of the above embodiment, when the antiparallel coupling film structure is applied to the ferromagnetic metal magnetization layer, only one of the ferromagnetic metal magnetization free layer and the ferromagnetic metal magnetization fixed layer is used. An anti-parallel coupling film structure may be applied to the structure, and the effect of making the ferromagnetic metal magnetization free layer an anti-parallel coupling film structure and the effect of making the ferromagnetic metal magnetization fixed layer an anti-parallel coupling film structure are obtained. It is done.
In addition, in the case where no condition is set for the size relationship between the area of the ferromagnetic metal magnetization fixed layer and the area of the ferromagnetic metal magnetization free layer, the vertical relationship in the lamination of these layers is also arbitrary. As described above, it is advantageous to make the fixed layer an upper layer and to have a small area.
　本発明は、磁界の測定に利用することができる。 The present invention can be used for magnetic field measurement.
１ 磁気センサー
２ 基板
３ 下部電極層
４ 強磁性金属磁化自由層
４ａ 容易磁化軸
５ 絶縁層
６ 強磁性金属磁化固定層
６ａ 容易磁化軸
７ 固定化促進層
８ 上部電極層
１０ トンネル磁気抵抗素子
１３ 電圧計
４１ 第１の強磁性体層（アモルファス強磁性体）
４２ 極薄非磁性体金属層
４３ 第２の強磁性体層
６１ 第１の強磁性体層
６２ 極薄非磁性体金属層
６３ 第２の強磁性体層
φ ねじれの角 DESCRIPTION OF SYMBOLS 1 Magnetic sensor 2 Substrate 3 Lower electrode layer 4 Ferromagnetic metal magnetization free layer 4a Easy magnetization axis 5 Insulating layer 6 Ferromagnetic metal magnetization fixed layer 6a Easy magnetization axis 7 Immobilization promoting layer 8 Upper electrode layer 10 Tunnel magnetoresistive element 13 Voltage Total 41 First ferromagnetic layer (amorphous ferromagnetic)
42 Ultrathin nonmagnetic metal layer 43 Second ferromagnetic layer 61 First ferromagnetic layer 62 Ultrathin nonmagnetic metal layer 63 Second ferromagnetic layer φ Twist angle

Claims (8)

  1. 　磁化の向きが固定された強磁性金属磁化固定層、外部からの磁界の影響を受けて磁化の向きが変化する強磁性金属磁化自由層、及び、前記強磁性金属磁化固定層と前記強磁性金属磁化自由層との間に配置された絶縁層を有し、前記強磁性金属磁化固定層の磁化の向きと前記強磁性金属磁化自由層の磁化の向きとの角度差に従ってトンネル効果により前記絶縁層の抵抗を変化させるトンネル磁気抵抗素子を含む磁気センサーにおいて、
    　前記強磁性金属磁化自由層は、アモルファス強磁性体を含むことを特徴とする磁気センサー。     A ferromagnetic metal magnetization fixed layer whose magnetization direction is fixed, a ferromagnetic metal magnetization free layer whose magnetization direction changes under the influence of an external magnetic field, and the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal An insulating layer disposed between the magnetization free layer and the tunneling effect according to an angular difference between a magnetization direction of the ferromagnetic metal magnetization fixed layer and a magnetization direction of the ferromagnetic metal magnetization free layer; In a magnetic sensor including a tunnel magnetoresistive element that changes the resistance of
    The magnetic sensor, wherein the ferromagnetic metal magnetization free layer includes an amorphous ferromagnet.
  2. 　ゼロ磁界での前記強磁性金属磁化自由層の容易磁化軸は、前記強磁性金属磁化固定層の容易磁化軸に対してねじれの位置にあることを特徴とする請求項１に記載の磁気センサー。 2. The magnetic sensor according to claim 1, wherein an easy magnetization axis of the ferromagnetic metal magnetization free layer in a zero magnetic field is in a twisted position with respect to an easy magnetization axis of the ferromagnetic metal magnetization fixed layer.
  3. 　前記強磁性金属磁化自由層は、第１の強磁性体と、前記絶縁層に接合する第２の強磁性体と、前記第１の強磁性体と前記第２の強磁性体との間に挟まれて存在する極薄非磁性体金属層とを備え、前記第１の強磁性体の磁化の向きと前記第２の強磁性体の磁化の向きとが、平行になる交換結合力を有する平行結合膜構造体、又は反平行になる交換結合力を有する反平行結合膜構造体であり、
    　前記強磁性金属磁化自由層の前記第１の強磁性体は、アモルファス強磁性体からなることを特徴とする請求項１または請求項２に記載の磁気センサー。     The ferromagnetic metal magnetization free layer includes a first ferromagnet, a second ferromagnet joined to the insulating layer, and between the first ferromagnet and the second ferromagnet. An ultra-thin non-magnetic metal layer sandwiched between them, and has an exchange coupling force in which the magnetization direction of the first ferromagnetic material and the magnetization direction of the second ferromagnetic material are parallel to each other A parallel coupling membrane structure, or an antiparallel coupling membrane structure having an exchange coupling force to be antiparallel,
    3. The magnetic sensor according to claim 1, wherein the first ferromagnet of the ferromagnetic metal magnetization free layer is made of an amorphous ferromagnet.
  4. 　前記強磁性金属磁化自由層は、前記第２の強磁性体がＣｏＦｅＢからなり、前記極薄非磁性体金属層がＲｕからなる反平行結合膜構造体であることを特徴とする請求項３に記載の磁気センサー。 4. The ferromagnetic metal magnetization free layer is an antiparallel coupling film structure in which the second ferromagnetic material is made of CoFeB and the ultrathin nonmagnetic metal layer is made of Ru. The described magnetic sensor.
  5. 　前記アモルファス強磁性体からなる前記強磁性金属磁化自由層の前記第１の強磁性体は、１０ｎｍから１００ｎｍの膜厚であることを特徴とする請求項３に記載の磁気センサー。 The magnetic sensor according to claim 3, wherein the first ferromagnetic body of the ferromagnetic metal magnetization free layer made of the amorphous ferromagnetic body has a thickness of 10 nm to 100 nm.
  6. 　前記極薄非磁性体金属層は、０．４ｎｍから１．５ｎｍの膜厚であることを特徴とする請求項３に記載の磁気センサー。 The magnetic sensor according to claim 3, wherein the ultrathin nonmagnetic metal layer has a thickness of 0.4 nm to 1.5 nm.
  7. 　ゼロ磁界での前記強磁性金属磁化自由層の容易磁化軸と、前記強磁性金属磁化固定層の容易磁化軸とのねじれの角は、４５度から１３５度であることを特徴とする請求項２から請求項６のうちいずれか一に記載の磁気センサー。 The twist angle between the easy magnetization axis of the ferromagnetic metal magnetization free layer and the easy magnetization axis of the ferromagnetic metal magnetization fixed layer in a zero magnetic field is 45 degrees to 135 degrees. The magnetic sensor according to claim 6.
  8. 　磁化の向きが固定された強磁性金属磁化固定層、外部からの磁界の影響を受けて磁化の向きが変化する強磁性金属磁化自由層、及び、前記強磁性金属磁化固定層と前記強磁性金属磁化自由層との間に配置された絶縁層を有し、前記強磁性金属磁化固定層の磁化の向きと前記強磁性金属磁化自由層の磁化の向きとの角度差に従ってトンネル効果により前記絶縁層の抵抗を変化させるトンネル磁気抵抗素子を含む磁気センサーを製造する方法であって、
    　熱処理を行う前の、前記強磁性金属磁化固定層および前記強磁性金属磁化自由層に対して、外部磁界を印加しながら第１の温度で第１の熱処理を行い、該第１の温度よりも低い第２の温度でかつ前記第１の熱処理とは向きを異ならせて外部磁界を印加しながら第２の熱処理を行うことで、熱処理後のゼロ磁界での前記強磁性金属磁化自由層の容易磁化軸を、前記強磁性金属磁化固定層の容易磁化軸に対してねじれの位置にするにあたり、
    　前記強磁性金属磁化自由層がアモルファス強磁性体を含み、前記第１の温度を３００℃から５００℃の範囲とし、前記第２の温度を２００℃から３５０℃の範囲とすることを特徴とする磁気センサーの製造方法。     A ferromagnetic metal magnetization fixed layer whose magnetization direction is fixed, a ferromagnetic metal magnetization free layer whose magnetization direction changes under the influence of an external magnetic field, and the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal An insulating layer disposed between the magnetization free layer and the tunneling effect according to an angular difference between a magnetization direction of the ferromagnetic metal magnetization fixed layer and a magnetization direction of the ferromagnetic metal magnetization free layer; A method of manufacturing a magnetic sensor including a tunnel magnetoresistive element that changes the resistance of
    A first heat treatment is performed at a first temperature while applying an external magnetic field to the ferromagnetic metal magnetization fixed layer and the ferromagnetic metal magnetization free layer before the heat treatment. By performing the second heat treatment while applying an external magnetic field at a low second temperature and in a different direction from the first heat treatment, the ferromagnetic metal magnetization free layer can be easily formed in a zero magnetic field after the heat treatment. In setting the magnetization axis to a position twisted with respect to the easy magnetization axis of the ferromagnetic metal magnetization fixed layer,
    The ferromagnetic metal magnetization free layer includes an amorphous ferromagnet, wherein the first temperature is in a range of 300 ° C. to 500 ° C., and the second temperature is in a range of 200 ° C. to 350 ° C. Manufacturing method of magnetic sensor.
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