JP2018006769A - Sensor, microphone, blood pressure sensor, and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor, a microphone, a blood pressure sensor, and a touch panel sensitivity of which can be improved.SOLUTION: A sensor includes a deformable substrate, and a strain detection element provided on the substrate. The strain detection element includes a first layer having first magnetization, a second layer having second magnetization which varies according to deformation of the substrate, an intermediate layer provided between the first layer and the second layer, and a third layer having third magnetization. The second layer is provided between the intermediate layer and the third layer. An angle between the third magnetization and the first magnetization is 30° to 60°, or 120° to 150°.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a sensor, a microphone, a blood pressure sensor, and a touch panel.

  Examples of pressure sensors using MEMS (Micro Electro Mechanical Systems) technology include a piezoresistance change type and a capacitance type. On the other hand, a pressure sensor using a spin technique has been proposed. In a pressure sensor using a spin technique, a resistance change corresponding to strain is detected. For example, in a strain sensing element used for a pressure sensor using a spin technique, an improvement in sensitivity is desired.

M. Lohndorf et al., "Highly sensitive strain sensors based on magnetic tunneling junctions" Appl. Phys. Lett., 81, 313, (2002). D. Meyners et al., "Pressure sensor based on magnetic tunnel junctions", J. Appl. Phys. 105, 07C914 (2009).

  Embodiments of the present invention provide a sensor, a microphone, a blood pressure sensor, and a touch panel that can improve sensitivity.

  According to the embodiment, the sensor includes a deformable substrate and a strain sensing element provided on the substrate. The strain sensing element includes a first layer having a first magnetization, a second layer having a second magnetization, and the second magnetization changing according to deformation of the substrate, the first layer, and the second layer. And an intermediate layer provided between and a third layer having a third magnetization. The second layer is provided between the intermediate layer and the third layer. The angle between the third magnetization and the first magnetization is 30 ° to 60 °, or 120 ° to 150 °.

FIG. 1A and FIG. 1B are schematic views showing a strain sensing element according to the first embodiment. FIG. 2A to FIG. 2C are schematic views showing the operation of the strain sensing element according to the first embodiment. 1 is a schematic perspective view showing a strain sensing element according to a first embodiment. FIG. 4A to FIG. 4E are schematic perspective views showing the bias layer of the first embodiment. FIG. 5A and FIG. 5B are schematic perspective views showing the difference in the bias direction of the embodiment. It is a typical perspective view which shows another distortion sensing element which concerns on 1st Embodiment. It is a typical perspective view which shows another distortion sensing element which concerns on 1st Embodiment. FIG. 8A to FIG. 8F are schematic cross-sectional views illustrating the magnetization pinned direction of the magnetization pinned layer, the magnetization pinned direction of the bias magnetic layer, and the bias direction applied to the magnetization free layer. FIG. 9A to FIG. 9D are graphs showing examples of results of magnetic characteristics before element processing of the laminates of the first example and the first comparative example. FIG. 10A to FIG. 10E are graphs showing examples of results of strain sensor characteristics of the strain sensing element 100 of the first embodiment. Fig.11 (a)-FIG.11 (e) are graphs which show the example of the strain sensor evaluation result of the strain sensing element of a 1st comparative example. It is a graph showing the example of the evaluation result of the gauge factor in various bias magnetic fields. FIG. 13A to FIG. 13F are schematic views showing the in-plane angle dependence of the free energy of the magnetization free layer of the embodiment. FIG. 14A to FIG. 14F are schematic views showing the in-plane angle dependence of the free energy of the magnetization free layer of the comparative example. FIG. 15A to FIG. 15D are graphs showing examples of results of magnetic characteristics before element processing of the laminated bodies of the second to fourth examples. FIG. 16A to FIG. 16D are schematic views for explaining another strain sensing element according to the embodiment. FIG. 17A to FIG. 17D are schematic views for explaining another strain sensing element according to the embodiment. It is a typical perspective view which shows another distortion sensing element used for embodiment. It is a typical perspective view which shows another distortion sensing element used for embodiment. It is a schematic plan view showing an example of a bias direction of a bias layer and a bias direction of a hard bias. FIG. 21A and FIG. 21B are schematic views showing a strain sensing element according to the second embodiment. FIG. 22A to FIG. 22C are schematic diagrams illustrating the operation of the strain sensing element according to the second embodiment. It is a typical perspective view which shows the distortion | strain detection element used for 2nd Embodiment. FIG. 24A and FIG. 24B are schematic perspective views showing the bias layer of the second embodiment. FIG. 25A to FIG. 25D are graphs showing examples of results of magnetic characteristics before element processing of the laminated body of the fifth example. FIG. 26A to FIG. 26D are graphs showing examples of results of strain sensor characteristics of the strain sensing element of the fifth example. FIGS. 27A to 27D are graphs showing examples of the results of the strain sensor characteristics of the strain sensing element of the sixth embodiment. FIG. 28A to FIG. 28D are graphs showing examples of results of strain sensor characteristics of the strain sensing element of the seventh example. FIG. 29A to FIG. 29D are schematic views for explaining another strain sensing element according to the embodiment. FIG. 9 is a schematic plan view illustrating an example of a bias direction of each bias layer and a bias direction of a hard bias in the second embodiment. FIG. 10 is a schematic perspective view illustrating a pressure sensor according to a third embodiment. FIGS. 32A to 32D are schematic plan views showing the relationship between the shape of the substrate and the direction of the bias layer of the first embodiment. FIG. 33A to FIG. 33D are schematic plan views showing the relationship between the shape of the substrate and the direction of the bias layer of the second embodiment. FIG. 34A and FIG. 34B are schematic views illustrating another pressure sensor according to the third embodiment. FIG. 35A to FIG. 35C are schematic perspective views illustrating a pressure sensor according to the third embodiment. FIG. 36A to FIG. 36E are schematic cross-sectional views in order of the processes, illustrating the manufacturing direction of the pressure sensor according to the embodiment. Fig.37 (a)-FIG.37 (c) are schematic diagrams which show the pressure sensor which concerns on embodiment. FIG. 38A and FIG. 38B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 39A and FIG. 39B are schematic views showing a method for manufacturing a pressure sensor according to the embodiment. FIG. 40A and FIG. 40B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 41A and FIG. 41B are schematic views showing a method for manufacturing a pressure sensor according to the embodiment. FIG. 42A and FIG. 42B are schematic views showing a method for manufacturing a pressure sensor according to the embodiment. FIG. 43A and FIG. 43B are schematic views showing a manufacturing method of the pressure sensor according to the embodiment. FIG. 44A and FIG. 44B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 45A and FIG. 45B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 46A and FIG. 46B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 47A and FIG. 47B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 48A and FIG. 48B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. FIG. 49A and FIG. 49B are schematic views showing the method for manufacturing the pressure sensor according to the embodiment. It is a schematic area top view which shows the microphone which concerns on 4th Embodiment. It is typical sectional drawing which shows the acoustic microphone which concerns on 5th Embodiment. FIG. 52A and FIG. 52B are schematic views showing a blood pressure sensor according to the sixth embodiment. It is a schematic plan view which shows the touchscreen which concerns on 7th Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
In the present specification and drawings, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

(First embodiment)
FIG. 1A and FIG. 1B are schematic views illustrating the strain sensing element according to the first embodiment.
FIG. 1A is a schematic cross-sectional view illustrating a pressure sensor using a strain sensing element. FIG. 1B is a schematic perspective view of the strain sensing element.

  As shown in FIG. 1A, the strain sensing element 100 is used for the pressure sensor 200. The pressure sensor 200 includes a substrate 210 and the strain sensing element 100. The substrate 210 has a flexible region. The substrate 210 can be deformed. The strain sensing element 100 is fixed to the substrate 210. In the present specification, the fixed state includes a directly fixed state and a state indirectly fixed by another element. For example, the state where the strain sensing element 100 is fixed to the substrate 210 includes a state where the relative position between the strain sensing element 100 and the substrate 210 is fixed. The strain sensing element 100 is provided on a part of the substrate 210, for example.

  In the specification of the application, the state of “provided on” includes not only the state of being provided in direct contact but also the state of being provided with another element inserted therebetween.

When a force 801 is applied to the substrate 210, the substrate 210 is deformed. As the substrate 210 is deformed, the strain sensing element 100 is distorted.
In the strain sensing element 100 according to the embodiment, for example, when the substrate 210 is deformed by an external force, the strain sensing element 100 is distorted. The strain sensing element 100 converts this change in strain into a change in electrical resistance.

As illustrated in FIG. 1B, the strain sensing element 100 according to the embodiment includes a first magnetic layer 10, a second magnetic layer 20, an intermediate layer 30, and a bias layer 40.
For example, the direction from the first magnetic layer 10 toward the second magnetic layer 20 is the Z-axis direction (stacking direction). One direction perpendicular to the Z-axis direction is taken as an X-axis direction. A direction perpendicular to the Z-axis direction and the X-axis direction is taken as a Y-axis direction.

  The bias layer 40 is provided separately from the first magnetic layer 10 in the stacking direction. The second magnetic layer 20 is provided between the first magnetic layer 10 and the bias layer 40. An intermediate layer 30 is provided between the first magnetic layer 10 and the second magnetic layer 20. The bias layer 40 is in contact with the second magnetic layer 20.

The first magnetic layer 10 is, for example, a reference layer. As the reference layer, a magnetization fixed layer or a magnetization free layer is used.
The second magnetic layer 20 is, for example, a magnetization free layer. When stress is applied to the strain sensing element 100 and strain occurs in the strain sensing element 100, the magnetization of the second magnetic layer 20 changes. For example, the change in magnetization of the second magnetic layer 20 is easier than the change in magnetization of the first magnetic layer 10. As a result, the relative angle between the magnetization of the first magnetic layer 10 and the magnetization of the second magnetic layer 10 changes.

Next, an example of the operation of the strain sensing element 100 will be described.
FIG. 2A to FIG. 2C are schematic views illustrating the operation of the strain sensing element according to the first embodiment.
FIG. 2A corresponds to a state (tensile state STt) when a tensile stress ts is applied to the strain sensing element 100. FIG. 2B corresponds to a state when the strain sensing element 100 has no strain (no strain state ST0). FIG. 2C corresponds to a state when the compressive stress cs is applied to the strain sensing element 100 (compressed state STc).

  In FIG. 2A to FIG. 2C, the first magnetic layer 10, the second magnetic layer 20, and the intermediate layer 30 are drawn and the bias layer 40 is omitted for easy understanding of the drawings. ing. In this example, the second magnetic layer 20 is a magnetization free layer, and the first magnetic layer 10 is a magnetization fixed layer.

  The operation in which the strain sensing element 100 functions as a strain sensor is based on the application of the “inverse magnetostriction effect” and the “magnetoresistance effect”. The “inverse magnetostriction effect” is obtained in the ferromagnetic layer used for the magnetization free layer. The “magnetoresistance effect” is manifested in a laminated film of a magnetization free layer, an intermediate layer, and a reference layer (for example, a magnetization fixed layer).

  The “inverse magnetostriction effect” is a phenomenon in which the magnetization of a ferromagnetic material changes due to the strain generated in the ferromagnetic material. That is, when an external strain is applied to the laminate of the strain sensing element 100, the magnetization direction of the magnetization free layer changes. As a result, the relative angle between the magnetization of the magnetization free layer and the magnetization of the reference layer (for example, the magnetization fixed layer) changes. At this time, a change in electrical resistance is caused by the “magnetoresistance effect (MR effect)”. The MR effect includes, for example, a GMR (Giant magnetoresistance) effect or a TMR (Tunneling magnetoresistance) effect. By passing a current through the stacked body, the MR effect appears by reading the change in the relative angle of the magnetization direction as the change in electrical resistance. For example, strain is generated in the stacked body (strain sensing element 100), and the magnetization direction of the magnetization free layer changes due to the strain, and the magnetization direction of the magnetization free layer and the magnetization direction of the reference layer (for example, the magnetization fixed layer) The relative angle of, changes. That is, the MR effect is manifested by the inverse magnetostrictive effect.

  When the ferromagnetic material used for the magnetization free layer has a positive magnetostriction constant, the angle between the direction of magnetization and the direction of tensile strain is reduced, and the angle between the direction of magnetization and the direction of compressive strain is increased. The direction of magnetization changes. When the ferromagnetic material used for the magnetization free layer has a negative magnetostriction constant, the angle between the magnetization direction and the tensile strain direction is increased, and the angle between the magnetization direction and the compression strain direction is decreased. The direction of magnetization changes.

  When the combination of materials of the stack of the magnetization free layer, the intermediate layer, and the reference layer (for example, the magnetization fixed layer) has a positive magnetoresistance effect, the electrical resistance is obtained when the relative angle between the magnetization free layer and the magnetization fixed layer is small. Decrease. When the combination of the materials of the laminate of the magnetization free layer, the intermediate layer, and the reference layer (for example, the magnetization fixed layer) has a negative magnetoresistance effect, the electrical resistance when the relative angle between the magnetization free layer and the magnetization fixed layer is small Will increase.

  Hereinafter, the ferromagnetic materials used for the magnetization free layer and the reference layer (for example, the magnetization fixed layer) have positive magnetostriction constants, respectively, and the magnetization free layer, the intermediate layer, and the reference layer (for example, the magnetization fixed layer) An example of a change in magnetization will be described with respect to an example in which a laminated body including a positive magnetoresistive effect.

  As shown in FIG. 2B, in the unstrained state ST0 (for example, the initial state) without strain, the magnetization 20m of the second magnetic layer 20 and the magnetization 10m of the first magnetic layer 10 (for example, the magnetization fixed layer). And the relative angle between them is set to a predetermined value. The magnetization direction of the magnetic layer in the initial state is set by, for example, a hard bias or the shape anisotropy of the magnetic layer. In this example, the magnetization 20m of the second magnetic layer 20 (magnetization free layer) and the magnetization 10m of the first magnetic layer 10 (for example, a magnetization fixed layer) intersect each other.

  As shown in FIG. 2A, when a tensile stress ts is applied in the tensile state STt, a strain corresponding to the tensile stress ts is generated in the strain sensing element 100. At this time, the magnetization 20m of the second magnetic layer 20 (magnetization free layer) changes from the unstrained state ST0 so that the angle between the magnetization 20m and the direction of the tensile stress ts becomes small. In the example shown in FIG. 2A, when a tensile stress ts is applied, the magnetization 20m of the second magnetic layer 20 (magnetization free layer) and the first magnetic layer 10 (for example, compared to the unstrained state ST0) The relative angle between the magnetization 10m of the magnetization fixed layer) becomes small. Thereby, the electrical resistance in the strain sensing element 100 is reduced as compared with the electrical resistance in the unstrained state ST0.

  As shown in FIG. 2C, when the compressive stress cs is applied in the compression state STc, the magnetization 20m of the second magnetic layer 20 (magnetization free layer) is changed between the magnetization 20m and the direction of the compression stress cs. It changes from the unstrained state ST0 so that the angle increases. In the example shown in FIG. 2C, when compressive stress cs is applied, the magnetization 20m of the second magnetic layer 20 (magnetization free layer) and the first magnetic layer 10 (for example, compared to the unstrained state ST0) The relative angle between the magnetization 10m of the magnetization fixed layer) is increased. Thereby, the electrical resistance in the strain sensing element 100 increases.

  As described above, in the strain sensing element 100, a change in strain generated in the strain sensing element 100 is converted into a change in electrical resistance. In the above operation, the amount of change (dR / R) in electrical resistance per unit strain (dε) is referred to as a gauge factor (GF). By using a strain sensing element having a high gauge factor, a highly sensitive strain sensor can be obtained.

  As shown in FIG. 1B, in the strain sensing element 100 including the bias layer 40 provided in contact with the second magnetic layer 20 (magnetization free layer), the bias layer 40 to the second magnetic layer 20 (magnetization free layer). ), The anisotropic magnetic field of the second magnetic layer 20 (magnetization free layer) can be improved to an appropriate value. By improving the anisotropic magnetic field of the second magnetic layer 20 (magnetization free layer), the reversibility of the change of the magnetization 20m of the second magnetic layer 20 (magnetization free layer) can be increased, and a high gauge factor is obtained. be able to. Details of the improvement in reversibility of the change in magnetization of the magnetization free layer with respect to strain will be described later.

  When the dimension of the strain sensing element 100 is reduced, a demagnetizing field is generated inside the second magnetic layer 20 (magnetization free layer) due to the influence of the magnetic pole at the element end of the second magnetic layer 20 (magnetization free layer). However, the magnetization 20m may be disturbed. When the magnetization 20m is disturbed, the relative angle change between the magnetization 10m of the first magnetic layer (for example, the magnetization fixed layer) and the magnetization 20m of the second magnetic layer (magnetization free layer) due to the strain of the strain sensing element 100 is changed. May be reduced. Reducing the demagnetizing field of the second magnetic layer 20 (magnetization free layer) is one of the important matters in providing a highly sensitive strain sensor in the strain sensing element 100 having a relatively small size. Improving the anisotropic magnetic field of the second magnetic layer 20 (magnetization free layer) is also effective in reducing the influence of such a demagnetizing field. Thereby, high strain detection sensitivity can be realized even in the strain detection element 100 having a relatively small size. As a result, the strain sensing element 100 having both high resolution and high sensitivity can be provided.

An example of the strain sensing element 100 according to the first embodiment will be described.
In the following, the description of “material A / material B” indicates a state in which a layer of material B is provided on a layer of material A.

FIG. 3 is a schematic perspective view illustrating the strain sensing element according to the first embodiment.
As illustrated in FIG. 3, the strain sensing element 100 a used in the embodiment includes the first electrode E <b> 1, the underlayer 50, the pinning layer 60, the second magnetization fixed layer 12, the magnetic coupling layer 13, The first magnetization fixed layer 11, the intermediate layer 30, the second magnetic layer 20, the bias layer 40, the cap layer 70, and the second electrode E <b> 2 are included. The first magnetization fixed layer 11 corresponds to the first magnetic layer 10. An underlayer 50 is provided between the first electrode E1 and the second electrode E2. A pinning layer 60 is provided between the foundation layer 50 and the second electrode E2. The second magnetization fixed layer 12 is provided between the pinning layer 60 and the second electrode E2. A magnetic coupling layer 13 is provided between the second magnetization fixed layer 12 and the second electrode E2. The first magnetization fixed layer 11 is provided between the magnetic coupling layer 13 and the second electrode E2. The intermediate layer 30 is provided between the first magnetization fixed layer 11 and the second electrode E2. The second magnetic layer 20 is provided between the intermediate layer 30 and the second electrode E2. A bias layer 40 is provided between the second magnetic layer 20 and the second electrode E2. A cap layer 70 is provided between the bias layer 40 and the second electrode E2.

For example, Ta / Ru is used for the underlayer 50. The thickness of the Ta layer (the length in the Z-axis direction) is, for example, 3 nanometers (nm). The thickness of this Ru layer is 2 nm, for example.
For the pinning layer 60, for example, an IrMn layer having a thickness of 7 nm is used.

For the second magnetization fixed layer 12, for example, a Co ₇₅ Fe ₂₅ layer having a thickness of 2.5 nm is used.
As the magnetic coupling layer 13, for example, a Ru layer having a thickness of 0.9 nm is used.
For the first magnetization fixed layer 11, for example, a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used. For the intermediate layer 30, for example, an MgO layer having a thickness of 2.0 nm is used.

For the second magnetic layer 20, for example, Co ₄₀ Fe ₄₀ B ₂₀ having a thickness of 4 nm is used.
For the bias layer 40, for example, Cu (5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm) is used.
For example, Ta / Ru is used for the cap layer 70. The thickness of this Ta layer is 1 nm, for example. The thickness of this Ru layer is 5 nm, for example.

  For example, at least one of aluminum (Al), aluminum copper alloy (Al-Cu), copper (Cu), silver (Ag), and gold (Au) is used for the first electrode E1 and the second electrode E2. It is done. By using such a material having a relatively small electric resistance as the first electrode E1 and the second electrode E2, a current can be efficiently passed through the strain sensing element 100a. A nonmagnetic material can be used for the first electrode E1.

  The first electrode E1 includes, for example, an underlayer (not shown) for the first electrode E1, a cap layer (not shown) for the first electrode E1, and Al, Al− provided therebetween. And at least one layer of Cu, Cu, Ag, and Au. For example, tantalum (Ta) / copper (Cu) / tantalum (Ta) is used for the first electrode E1. By using Ta as the base layer for the first electrode E1, for example, the adhesion between the substrate 210 and the first electrode E1 is improved. As the base layer for the first electrode E1, titanium (Ti), titanium nitride (TiN), or the like may be used.

  By using Ta as the cap layer of the first electrode E1, oxidation of copper (Cu) or the like under the cap layer can be prevented. As the cap layer for the first electrode E1, titanium (Ti), titanium nitride (TiN), or the like may be used.

  For the underlayer 50, for example, a stacked structure including a buffer layer (not shown) and a seed layer (not shown) can be used. This buffer layer, for example, reduces the roughness of the surface of the first electrode E1 or the substrate 210, and improves the crystallinity of the layer stacked on this buffer layer. As the buffer layer, for example, at least one selected from the group consisting of tantalum (Ta), titanium (Ti), vanadium (V), tungsten (W), zirconium (Zr), hafnium (Hf), and chromium (Cr) Is used. As the buffer layer, an alloy containing at least one material selected from these materials may be used.

  The thickness of the buffer layer in the underlayer 50 is preferably 1 nm or more and 10 nm or less. The thickness of the buffer layer is more preferably 1 nm or more and 5 nm or less. If the buffer layer is too thin, the buffer effect is lost. If the buffer layer is too thick, the strain sensing element 100a is excessively thick. A seed layer is formed on the buffer layer, and the seed layer may have a buffer effect. In this case, the buffer layer may be omitted. As the buffer layer, for example, a Ta layer having a thickness of 3 nm is used.

  The seed layer of the underlayer 50 controls the crystal orientation of the layer stacked on the seed layer. The seed layer controls the crystal grain size of the layer stacked on the seed layer. As the seed layer, an fcc structure (face-centered cubic structure), an hcp structure (hexagonal close-packed structure), or a bcc structure (body-centered cubic structure) Structure) metal or the like is used.

  By using ruthenium (Ru) having an hcp structure, NiFe having an fcc structure, or Cu having an fcc structure as a seed layer in the underlayer 50, for example, the crystal orientation of the spin valve film on the seed layer can be changed. The fcc (111) orientation can be obtained. For the seed layer, for example, a Cu layer having a thickness of 2 nm or a Ru layer having a thickness of 2 nm is used. In order to increase the crystal orientation of the layer formed on the seed layer, the thickness of the seed layer is preferably 1 nm or more and 5 nm or less. The thickness of the seed layer is more preferably 1 nm or more and 3 nm or less. Thereby, the function as a seed layer for improving the crystal orientation is sufficiently exhibited.

  On the other hand, for example, when it is not necessary to orient the layer formed on the seed layer (for example, when an amorphous magnetization free layer is formed), the seed layer may be omitted. As the seed layer, for example, a Cu layer having a thickness of 2 nm is used.

  For example, the pinning layer 60 imparts unidirectional anisotropy to the second magnetization fixed layer 12 (ferromagnetic layer) formed on the pinning layer 60, so that Fix the magnetization. For the pinning layer 60, for example, an antiferromagnetic layer is used. For the pinning layer 60, for example, at least one selected from the group consisting of IrMn, PtMn, PdPtMn, and RuRhMn is used. In order to impart sufficient strength of unidirectional anisotropy, the thickness of the pinning layer 60 is appropriately set.

When PtMn or PdPtMn is used as the pinning layer 60, the thickness of the pinning layer 60 is preferably 8 nm or more and 20 nm or less. The thickness of the pinning layer 60 is more preferably 10 nm or more and 15 nm or less. When IrMn is used as the pinning layer 60, unidirectional anisotropy can be imparted with a thinner thickness than when PtMn is used as the pinning layer 60. In this case, the thickness of the pinning layer 60 is preferably 4 nm or more and 18 nm or less. The thickness of the pinning layer 60 is more preferably 5 nm or more and 15 nm or less. For the pinning layer 60, for example, an Ir ₂₂ Mn ₇₈ layer having a thickness of 7 nm is used.

A hard magnetic layer may be used as the pinning layer 60. As a hard magnetic layer, for example, CoPt (ratio of Co is, 50at.% Or more 85 at.% Or _{less), (Co x Pt 100-} x) 100-y Cr y (x is, 50at.% Or more 85 at.% Or less Yes, y may be 0 at.% Or more and 40 at.% Or less), or FePt (the ratio of Pt is 40 at.% Or more and 60 at.% Or less).

The second magnetization fixed layer 12 includes, for example, a Co _x Fe _100-x alloy (x is 0 at.% Or more and 100 at.% Or less), a Ni _x Fe _100-x alloy (x is 0 at.% Or more and 100 at.% Or more). Or a material obtained by adding a nonmagnetic element thereto. As the second magnetization fixed layer 12, for example, at least one selected from the group consisting of Co, Fe, and Ni is used. An alloy containing at least one material selected from these materials may be used as the second magnetization fixed layer 12. The second magnetization pinned layer _12, a _{(Co x Fe 100-x)} 100-y B y alloys (x is, 0 atomic.% Or more 100at is at.% Or less, y is, 0 atomic.% Or more 30 at.% Or less) It can also be used. The second magnetization pinned layer _12, the variation of _{(Co x} Fe _100-x) By using the amorphous alloy _{100-y B y,} even when the size of the strain detecting elements 100a is small, the characteristics of the strain detecting elements 100a Can be suppressed.

  The thickness of the second magnetization fixed layer 12 is preferably 1.5 nm or more and 5 nm or less, for example. Thereby, for example, the intensity of the unidirectional anisotropic magnetic field by the pinning layer 60 can be further increased. For example, the strength of the antiferromagnetic coupling magnetic field between the second magnetization fixed layer 12 and the first magnetization fixed layer 11 is increased through the magnetic coupling layer 13 formed on the second magnetization fixed layer 12. be able to. For example, the magnetic film thickness of the second magnetization fixed layer 12 (the product of the saturation magnetization Bs and the thickness t (Bs · t)) is preferably substantially equal to the magnetic film thickness of the first magnetization fixed layer 11. .

The saturation magnetization of Co ₄₀ Fe ₄₀ B _{20 in} the thin film is about 1.9 T (Tesla). For example, when a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used as the first magnetization fixed layer 11, the magnetic film thickness of the first magnetization fixed layer 11 is 1.9 T × 3 nm, which is 5.7 Tnm. Become. On the other hand, the saturation magnetization of Co ₇₅ Fe ₂₅ is about 2.1T. The thickness of the second magnetization fixed layer 12 that can obtain a magnetic film thickness equal to the above is 5.7 Tnm / 2.1T, which is 2.7 nm. In this case, it is preferable to use a Co ₇₅ Fe ₂₅ layer having a thickness of about 2.7 nm as the second magnetization fixed layer 12. As the second magnetization fixed layer 12, for example, a Co ₇₅ Fe ₂₅ layer having a thickness of 2.5 nm is used.

In the strain sensing element 100a, a synthetic pin structure is used by the second magnetization fixed layer 12, the magnetic coupling layer 13, and the first magnetization fixed layer 11. Instead, a single pin structure composed of a single magnetization fixed layer may be used. When the single pin structure is used, for example, a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used as the magnetization fixed layer. The same material as the material of the second magnetization fixed layer 12 described above may be used as the ferromagnetic layer used for the single pin structure magnetization fixed layer.

  The magnetic coupling layer 13 generates antiferromagnetic coupling between the second magnetization fixed layer 12 and the first magnetization fixed layer 11. The magnetic coupling layer 13 forms a synthetic pin structure. For example, Ru is used as the magnetic coupling layer 13. The thickness of the magnetic coupling layer 13 is preferably 0.8 nm or more and 1 nm or less, for example. Any material other than Ru may be used for the magnetic coupling layer 13 as long as the material generates sufficient antiferromagnetic coupling between the second magnetization fixed layer 12 and the first magnetization fixed layer 11. The thickness of the magnetic coupling layer 13 can be set to a thickness of 0.8 nm or more and 1 nm or less corresponding to a second peak (2nd peak) of RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling. Furthermore, the thickness of the magnetic coupling layer 13 may be set to a thickness of 0.3 nm or more and 0.6 nm or less corresponding to the first peak (1st peak) of the RKKY coupling. For example, Ru having a thickness of 0.9 nm is used as the magnetic coupling layer 13. Thereby, highly reliable coupling can be obtained more stably.

The magnetic layer used for the first magnetization fixed layer 11 directly contributes to the MR effect. For example, a Co—Fe—B alloy is used as the first magnetization fixed layer 11. Specifically, as the first magnetization fixed layer 11, a (Co _x Fe _100-x ) _{100- y By} alloy (x is 0 at.% Or more and 100 at.% Or less, and y is 0 at.% Or more and 30 at. .% Or less) can also be used. The first magnetization fixed layer _11, in the case of using the _{(Co x Fe 100-x)} 100-y B y of the amorphous alloy, for example, in a case where the size of the strain detecting elements 100a is smaller, due to the grain Variations between elements can be suppressed.

A layer (for example, a tunnel insulating layer (not shown)) formed on the first magnetization fixed layer 11 can be planarized. By planarizing the tunnel insulating layer, the defect density of the tunnel insulating layer can be reduced. As a result, a higher MR ratio can be obtained with a lower sheet resistance. For example, in the case of using MgO as a material of the tunnel insulating layer, a first magnetization fixing layer _{11, (Co x Fe 100-} x) by using a _{100-y B y} of the amorphous alloy, on top of the tunnel insulating layer The (100) orientation of the formed MgO layer can be strengthened. By increasing the (100) orientation of the MgO layer, a higher MR ratio can be obtained. The (Co _x Fe _100-x ) _100-y B _y alloy crystallizes using the (100) plane of the MgO layer as a template during annealing. Therefore, good crystal matching between MgO and _{(Co x Fe 100-x)} 100-y B y alloys are obtained. By obtaining good crystal matching, a higher MR ratio can be obtained.

  As the first magnetization fixed layer 11, for example, an Fe—Co alloy may be used in addition to the Co—Fe—B alloy.

  If the first magnetization fixed layer 11 is thicker, a larger MR change rate can be obtained. In order to obtain a larger fixed magnetic field, the first magnetization fixed layer 11 is preferably thin. A trade-off relationship exists in the thickness of the first magnetization fixed layer 11 between the MR change rate and the fixed magnetic field. When a Co—Fe—B alloy is used as the first magnetization fixed layer 11, the thickness of the first magnetization fixed layer 11 is preferably 1.5 nm or more and 5 nm or less. The thickness of the first magnetization fixed layer 11 is more preferably 2.0 nm or more and 4 nm or less.

In addition to the materials described above, the first magnetization fixed layer 11 is made of a Co ₉₀ Fe ₁₀ alloy having an fcc structure, a Co having an hcp structure, or a Co alloy having an hcp structure. As the first magnetization fixed layer 11, for example, at least one selected from the group consisting of Co, Fe, and Ni is used. As the first magnetization fixed layer 11, an alloy containing at least one material selected from these materials is used. As the first magnetization fixed layer 11, an FeCo alloy material having a bcc structure, 50 at. % Co alloy containing cobalt composition of 50% or more, or 50 at. By using a material (Ni alloy) having a Ni composition of at least%, for example, a larger MR change rate can be obtained.

Examples of the first magnetization fixed layer 11 include Co ₂ MnGe, Co ₂ FeGe, Co ₂ MnSi, Co ₂ FeSi, Co ₂ MnAl, Co ₂ FeAl, Co ₂ MnGa _0.5 Ge _0.5 , and Co ₂ FeGa. A Heusler magnetic alloy layer such as _0.5 Ge _0.5 can also be used. For example, as the first magnetization fixed layer 11, for example, a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used.

For example, the intermediate layer 30 breaks the magnetic coupling between the first magnetic layer 10 and the second magnetic layer 20. For the intermediate layer 30, for example, a metal, an insulator, or a semiconductor is used. For example, Cu, Au, or Ag is used as this metal. When a metal is used as the intermediate layer 30, the thickness of the intermediate layer 30 is, for example, about 1 nm to 7 nm. Examples of the insulator or semiconductor include magnesium oxide (such as MgO), aluminum oxide (such as Al ₂ O ₃ ), titanium oxide (such as TiO), zinc oxide (such as ZnO), or gallium oxide. (Ga—O) or the like is used. When an insulator or a semiconductor is used as the intermediate layer 30, the thickness of the intermediate layer 30 is, for example, about 0.6 nm to 2.5 nm. For example, a CCP (Current-Confined-Path) spacer layer may be used as the intermediate layer 30. When a CCP spacer layer is used as the spacer layer, for example, a structure in which a copper (Cu) metal path is formed in an insulating layer of aluminum oxide (Al ₂ O ₃ ) is used. For example, a 1.6 nm thick MgO layer is used as the intermediate layer 30.

A ferromagnetic material is used for the second magnetic layer 20. For the second magnetic layer 20, for example, a ferromagnetic material containing Fe, Co, and Ni can be used. As the material of the second magnetic layer 20, for example, FeCo alloy, NiFe alloy or the like is used. Further, the second magnetic layer 20 includes a Co—Fe—B alloy, an Fe—Co—Si—B alloy, an Fe—Ga alloy having a large λs (magnetostriction constant), an Fe—Co—Ga alloy, and Tb—M—Fe. An alloy, Tb-M1-Fe-M2 alloy, Fe-M3-M4-B alloy, Ni, Fe-Al, ferrite, or the like is used. In the Tb-M-Fe alloy described above, M is at least one selected from the group consisting of Sm, Eu, Gd, Dy, Ho, and Er. In the Tb-M1-Fe-M2 alloy described above, M1 is at least one selected from the group consisting of Sm, Eu, Gd, Dy, Ho, and Er. M2 is at least one selected from the group consisting of Ti, Cr, Mn, Co, Cu, Nb, Mo, W, and Ta. In the Fe-M3-M4-B alloy described above, M3 is at least one selected from the group consisting of Ti, Cr, Mn, Co, Cu, Nb, Mo, W, and Ta. M4 is at least one selected from the group consisting of Ce, Pr, Nd, Sm, Tb, Dy, and Er. Examples of the ferrite include Fe ₃ O ₄ and (FeCo) ₃ O ₄ ). The thickness of the second magnetic layer 20 is, for example, 2 nm or more.

A magnetic material containing boron may be used for the second magnetic layer 20. For the second magnetic layer 20, for example, an alloy containing at least one element selected from the group consisting of Fe, Co, and Ni and boron (B) may be used. For example, a Co—Fe—B alloy or an Fe—B alloy can be used. For example, a Co ₄₀ Fe ₄₀ B ₂₀ alloy can be used. In the case where an alloy containing at least one element selected from the group consisting of Fe, Co, and Ni and boron (B) is used for the second magnetic layer 20, as elements that promote high magnetostriction, Ga, Al, Si or W may be added. For example, an Fe—Ga—B alloy, an Fe—Co—Ga—B alloy, or an Fe—Co—Si—B alloy may be used. By using such a magnetic material containing boron, the coercive force (H _c ) of the second magnetic layer 20 is lowered, and the change of the magnetization 20m with respect to strain is facilitated. Thereby, high distortion sensitivity can be obtained.

  The boron concentration (for example, the composition ratio of boron) in the second magnetic layer 20 is 5 at. % (Atomic percent) or more is preferable. This makes it easier to obtain an amorphous structure. The boron concentration in the second magnetic layer 20 is 35 at. % Or less is preferable. If the boron concentration is too high, for example, the magnetostriction constant decreases. The boron concentration in the second magnetic layer 20 is, for example, 5 at. % Or more and 35 at. % Or less, preferably 10 at. % Or more and 30 at. % Or less is more preferable.

Fe _1-y B _y (0 <y ≦ 0.3) or (Fe _a X _1-a ) _1-y B _y (X = Co or Ni, When 0.8 ≦ a <1, 0 <y ≦ 0.3), it is easy to achieve both a large magnetostriction constant λ and a low coercive force, which is particularly preferable from the viewpoint of obtaining a high gauge factor. For example, Fe ₈₀ B ₂₀ (4 nm) can be used as the second magnetic layer 20. As the second magnetic layer 20, Co ₄₀ Fe ₄₀ B ₂₀ (0.5 nm) / Fe ₈₀ B ₂₀ (4 nm) can be used.

  The second magnetic layer 20 may have a multilayer structure. When an MgO tunnel insulating layer is used as the intermediate layer 30, it is preferable to provide a Co—Fe—B alloy layer in the portion of the second magnetic layer 20 that is in contact with the intermediate layer 30. Thereby, a high magnetoresistance effect is obtained. In this case, a Co—Fe—B alloy layer is provided on the intermediate layer 30, and another magnetic material having a large magnetostriction constant is provided on the Co—Fe—B alloy layer. When the second magnetic layer 20 has a multilayer structure, for example, Co—Fe—B (2 nm) / Fe—Co—Si—B (4 nm) or the like is used for the second magnetic layer 20.

  In the embodiment, the bias layer 40 is provided on the second magnetic layer 20. Details of the bias layer 40 will be described later.

  The cap layer 70 protects a layer provided under the cap layer 70. For the cap layer 70, for example, a plurality of metal layers are used. For the cap layer 70, for example, a two-layer structure (Ta / Ru) of a Ta layer and a Ru layer is used. The thickness of the Ta layer is 1 nm, for example, and the thickness of the Ru layer is 5 nm, for example. As the cap layer 70, another metal layer may be provided instead of the Ta layer or the Ru layer. The configuration of the cap layer 70 is arbitrary. For example, a nonmagnetic material can be used for the cap layer 70. Other materials may be used for the cap layer 70 as long as the layer provided under the cap layer 70 can be protected.

FIG. 4A to FIG. 4E are schematic perspective views illustrating the bias layer of the first embodiment.
FIG. 4A to FIG. 4E show a bias layer 40 provided for the first magnetic layer 10 (reference layer) / intermediate layer 30 / second magnetic layer 20 (magnetization free layer) stack. An example of a variation of the structure of the bias layer 40 in which the second magnetic layer 20 is provided between the intermediate layer 30 and the bias layer 40 is shown. In these examples, the first magnetic layer 10 corresponds to the first magnetization fixed layer 11.

  The bias layer 40a shown in FIG. 4A includes a first bias magnetic layer 41a, a bias pinning layer 42, and a separation layer 43. A separation layer 43 is provided between the second magnetic layer 20 and the bias pinning layer 42. A first bias magnetic layer 41 a is provided between the separation layer 43 and the bias pinning layer 42.

  The first bias magnetic layer 41a is made of, for example, a magnetic material. The magnetization of the first bias magnetic layer 41a is fixed in one direction by the bias pinning layer. The first bias magnetic layer 41a whose magnetization is fixed in one direction applies a bias to the second magnetic layer 20 by magnetic coupling such as exchange coupling. The separation layer 43 is formed of, for example, a nonmagnetic material, and physically separates the first bias magnetic layer 41a and the second magnetic layer 20 so that the first bias magnetic layer 41a and the second magnetic layer 20 are separated from each other. Adjust the strength of magnetic coupling between. Note that the separation layer 43 is not necessarily provided depending on the material of the first bias magnetic layer 41a.

For the separation layer 43, for example, 5 nm of Cu is used. For the first bias magnetic layer 41a, for example, 3 nm of Fe ₅₀ Co ₅₀ is used. For the bias pinning layer 42, for example, IrMn of 7 nm is used.

For the first bias magnetic layer 41a, for example, at least one selected from the group consisting of Co, Fe, and Ni can be used. As the first bias magnetic layer 41a, an alloy containing at least one material selected from the group consisting of Co, Fe, and Ni may be used. For example, the first bias magnetic layer 41a includes a Co _x Fe _100-x alloy (x is 0 at.% Or more and 100 at.% Or less), a Ni _x Fe _100-x alloy (x is 0 at.% Or more and 100 at.% Or less). Or the material which added the nonmagnetic element to these is used. As the first bias magnetic layer _{41a, (Co x Fe 100-} x) 100-y B y alloys (x is 0 atomic.% Or more 100 atomic.% Or less, y is 0 atomic.% Or more 30 at.% Or less) even if used Good. As the first bias magnetic layer _41a, to suppress the variation between _{(Co x} Fe _100-x) By using the amorphous alloy _{100-y B} y, strain detecting elements 100a of sizes distortion when a small sensing element 100a Can do. The thickness of the first bias magnetic layer 41a is preferably not less than 1.5 nm and not more than 5 nm, for example. Thereby, for example, the intensity of the unidirectional anisotropic magnetic field by the bias pinning layer 42 can be sufficiently obtained. For example, 3 nm Fe ₅₀ Co ₅₀ is used as the first bias magnetic layer 41a.

  For the separation layer 43, for example, a nonmagnetic material is used. The separation layer 43 is, for example, selected from the group of Cu, Ru, Rh, Ir, V, Cr, Nb, Mo, Ta, W, Rr, Au, Ag, Pt, Pd, Ti, Zr, Hf, and Hf A layer containing at least one element formed can be used. For example, 5 nm of Cu is used as the separation layer 43.

  The bias pinning layer 42 imparts unidirectional anisotropy to the first bias magnetic layer 41a formed in contact with the bias pinning layer 42 to fix the magnetization of the first bias magnetic layer 41a. For the bias pinning layer 42, for example, an antiferromagnetic layer is used. For the bias pinning layer 42, for example, at least one selected from the group consisting of Ir—Mn, Pt—Mn, Pd—Pt—Mn, and Ru—Rh—Mn is used. In order to impart sufficient strength of unidirectional anisotropy, the thickness of the bias pinning layer 42 is appropriately set.

When PtMn or PdPtMn is used as the bias pinning layer 42, the thickness of the bias pinning layer 42 is preferably 8 nm or more and 20 nm or less. The thickness of the bias pinning layer 42 is more preferably 10 nm or more and 15 nm or less. When IrMn is used as the bias pinning layer 42, unidirectional anisotropy can be imparted to the first bias magnetic layer 41a with a bias pinning layer 42 thinner than when PtMn is used as the bias pinning layer 42. . In this case, the thickness of the bias pinning layer 42 is preferably 4 nm or more and 18 nm or less. The thickness of the bias pinning layer 42 is more preferably 5 nm or more and 15 nm or less. For the bias pinning layer 42, for example, an Ir ₂₂ Mn ₇₈ layer having a thickness of 7 nm is used.

A hard magnetic layer may be used as the bias pinning layer 42. As a hard magnetic layer, for example, CoPt (ratio of Co is, 50at.% Or more 85 at.% Or _{less), (Co x Pt 100-} x) is _{100-y Cr y (x 50at} .% Or more 85 at.% Or less, y May be 0 at.% Or more and 40 at.% Or less), or FePt (the ratio of Pt is 40 at.% Or more and 60 at.% Or less).

FIG. 4B is a schematic perspective view showing another bias layer of the first embodiment.
The bias layer 40b illustrated in FIG. 4B includes a first bias magnetic layer 41a, a second bias magnetic layer 41b, a bias pinning layer 42, a separation layer 43, and a first magnetic coupling layer 44a. . A separation layer 43 is provided between the second magnetic layer 20 and the bias pinning layer 42. A first bias magnetic layer 41 a is provided between the separation layer 43 and the bias pinning layer 42. A first magnetic coupling layer 44 a is provided between the first bias magnetic layer 41 a and the bias pinning layer 42. A second bias magnetic layer 41 b is provided between the first magnetic coupling layer 44 a and the bias pinning layer 42.

  In the bias layer 40a shown in FIG. 4A, a single bias magnetic layer (first bias magnetic layer 41a) is provided. On the other hand, in the bias layer 40b shown in FIG. 4B, the two bias magnetic layers (the first bias magnetic layer 41a and the second bias magnetic layer 41b) are interposed via the first magnetic coupling layer 44a. Is provided. In this respect, the bias layer 40b shown in FIG. 4B is different from the bias layer 40a shown in FIG.

  The magnetization of the first bias magnetic layer 41a is set to be opposite to the magnetization of the second bias magnetic layer 41b adjacent via the first magnetic coupling layer 44a. In this way, by setting the magnetizations of the plurality of bias magnetic layers to antiparallel (180 °), the leakage magnetic field from the bias magnetic layer to the outside is suppressed, and magnetics other than bias application by exchange coupling to the second magnetic layer 20 are suppressed. Interference can be suppressed. Note that the separation layer 43 is not necessarily provided.

  The first magnetic coupling layer 44a generates antiferromagnetic coupling between the first bias magnetic layer 41a and the second bias magnetic layer 41b. The first magnetic coupling layer 44a forms a synthetic pin structure. For example, Ru is used as the first magnetic coupling layer 44a. The thickness of the first magnetic coupling layer 44a is preferably 0.8 nm or more and 1 nm or less. Any material other than Ru may be used for the first magnetic coupling layer 44a as long as the material generates sufficient antiferromagnetic coupling between the first bias magnetic layer 41a and the second bias magnetic layer 41b. The thickness of the first magnetic coupling layer 44a can be set to a thickness of 0.8 nm to 1 nm corresponding to a second peak (2nd peak) of RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling. Further, the thickness of the first magnetic coupling layer 44a may be set to a thickness of 0.3 nm or more and 0.6 nm or less corresponding to the first peak (1st peak) of the RKKY coupling. For example, Ru having a thickness of 0.9 nm is used as the first magnetic coupling layer 44a. Thereby, highly reliable coupling can be obtained more stably.

  The thickness of the first bias magnetic layer 41a is preferably not less than 1.5 nm and not more than 5 nm, for example. The thickness of the second bias magnetic layer 41b is preferably 1.5 nm or more and 5 nm or less, for example. Thereby, for example, the intensity of the unidirectional anisotropic magnetic field by the bias pinning layer 42 can be further increased. The magnetic film thickness (the product of the saturation magnetization Bs and the thickness t (Bs · t)) of the first bias magnetic layer 41a is preferably substantially equal to the magnetic film thickness of the second bias magnetic layer 41b.

When the same magnetic material is used for the first bias magnetic layer 41a and the second bias magnetic layer 41b, the thickness of the first bias magnetic layer 41a is preferably made equal to the thickness of the second bias magnetic layer 41b. When different magnetic materials are used for the first bias magnetic layer 41a and the second bias magnetic layer 41b, for example, Co ₄₀ Fe ₄₀ B ₂₀ is used for the first bias magnetic layer 41a, and Co ₇₅ Fe ₂₅ is used for the second bias magnetic layer 41b. When used, the saturation magnetization of Co ₄₀ Fe ₄₀ B _{20 in} the thin film is about 1.9 T (Tesla), and the saturation magnetization of Co ₇₅ Fe ₂₅ is about 2.1 T. For example, when a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used as the first bias magnetic layer 41a, the magnetic film thickness of the first bias magnetic layer 41a is 1.9 T × 3 nm. 7 Tnm. The thickness of the second bias magnetic layer 41b that can obtain a magnetic film thickness equal to the above is 5.7 Tnm / 2.1T, which is 2.7 nm. In this case, it is preferable to use Co ₇₅ Fe ₂₅ having a thickness of about 2.7 nm for the second bias magnetic layer 41b.

As the material of each layer included in the bias layer 40b illustrated in FIG. 4B, the same material as the material of each layer included in the bias layer 40a illustrated in FIG.
For the separation layer 43, for example, 5 nm of Cu is used. For the first bias magnetic layer 41a, for example, 2 nm of Fe ₅₀ Co ₅₀ is used. For example, 0.9 nm of Ru is used for the first magnetic coupling layer 44a. For the second bias magnetic layer 41b, for example, 2 nm of Fe ₅₀ Co ₅₀ is used. For the bias pinning layer 42, for example, IrMn of 7 nm is used.

FIG. 4C is a schematic perspective view showing another bias layer of the first embodiment.
The bias layer 40c shown in FIG. 4C includes a first bias magnetic layer 41a, a second bias magnetic layer 41b, a third bias magnetic layer 41c, a bias pinning layer 42, a separation layer 43, and a first layer. A magnetic coupling layer 44a and a second magnetic coupling layer 44b are included. A separation layer 43 is provided between the second magnetic layer 20 and the bias pinning layer 42. A first bias magnetic layer 41 a is provided between the separation layer 43 and the bias pinning layer 42. A first magnetic coupling layer 44 a is provided between the first bias magnetic layer 41 a and the bias pinning layer 42. A second bias magnetic layer 41 b is provided between the first magnetic coupling layer 44 a and the bias pinning layer 42. A second magnetic coupling layer 44b is provided between the second bias magnetic layer 41b and the bias pinning layer. A third bias magnetic layer 41 c is provided between the second magnetic coupling layer 44 b and the bias pinning layer 42.

  In the bias layer 40a shown in FIG. 4A, a single bias magnetic layer (first bias magnetic layer 41a) is provided. In the bias layer 40c shown in FIG. 4C, three bias magnetic layers (first bias magnetic layer 41a and second bias magnetic layer 41b are interposed via the first magnetic coupling layer 44a and the second magnetic coupling layer 44b. And a third bias magnetic layer 41c). In this respect, the bias layer 40c shown in FIG. 4C is different from the bias layer 40a shown in FIG.

  The magnetization of the first bias magnetic layer 41a is set to be opposite to the magnetization of the second bias magnetic layer 41b adjacent via the first magnetic coupling layer 44a. The magnetization of the second bias magnetic layer 41b is set to be opposite to the magnetization of the third bias magnetic layer 41c adjacent via the second magnetic coupling layer 44b. Thus, by making the magnetization directions of the plurality of bias magnetic layers antiparallel, the leakage magnetic field from the bias magnetic layer to the outside is suppressed, and magnetic interference other than bias application by exchange coupling to the second magnetic layer 20 is prevented. Can be suppressed. As will be described later, the bias direction can be appropriately selected by appropriately setting the number of bias magnetic layers to either an odd number or an even number. Note that the separation layer 43 is not necessarily provided.

When using three bias magnetic layers as shown in FIG. 4C, the magnetization of the first bias magnetic layer 41a is the same as the magnetization of the third bias magnetic layer 41c. The magnetization of the second bias magnetic layer 41b is opposite to the magnetization of the first bias magnetic layer 41a and the magnetization of the third bias magnetic layer 41c. When using an odd number of bias magnetic layers, the sum of the magnetic film thicknesses of the bias magnetic layers facing in the same direction is preferably made equal to the sum of the magnetic film thicknesses of the bias magnetic layers facing in the opposite direction. According to this, the leakage magnetic field can be reduced. For example, when three bias magnetic layers are used as shown in FIG. 4C, the sum of the magnetic film thicknesses of the first bias magnetic layer 41a and the third bias magnetic layer 41c is set to the magnetic value of the second bias magnetic layer 41b. It is preferable to make it equal to the film thickness.
The bias layer may include four or more bias magnetic layers.

As the material of each layer included in the bias layer 40c illustrated in FIG. 4C, the same material as the material of each layer included in the bias layer 40a illustrated in FIG.
For the separation layer 43, for example, 5 nm of Cu is used. For the first bias magnetic layer 41a, for example, 2 nm of Fe ₅₀ Co ₅₀ is used. For example, 0.9 nm of Ru is used for the first magnetic coupling layer 44a. For the second bias magnetic layer 41b, for example, 4 nm of Fe ₅₀ Co ₅₀ is used. For example, Ru of 0.9 nm is used for the second magnetic coupling layer 44b. For the third bias magnetic layer 41c, for example, 2 nm of Fe ₅₀ Co ₅₀ is used. For the bias pinning layer 42, for example, IrMn of 7 nm is used.

FIG. 4D is a schematic perspective view showing another bias layer of the first embodiment.
The bias layer 40d shown in FIG. 4D includes a first bias magnetic layer 41a and a separation layer 43. A separation layer 43 is provided between the second magnetic layer 20 and the first bias magnetic layer 41a.

  In the bias layer 40a shown in FIG. 4A, a bias pinning layer 42 is provided in contact with the first bias magnetic layer 41a. In the bias layer 40d shown in FIG. 4D, the bias pinning layer 42 is not provided. In this respect, the bias layer 40d shown in FIG. 4D is different from the bias layer 40a shown in FIG. Note that the separation layer 43 is not necessarily provided.

When the bias pinning layer 42 is not provided as shown in FIG. 4D, for example, a hard magnetic layer is used as the first bias magnetic layer 41a. As a hard magnetic layer, for example, CoPt (ratio of Co is, 50at.% Or more 85 at.% Or _{less), (Co x Pt 100-} x) is _{100-y Cr y (x 50at} .% Or more 85 at.% Or less, y May be 0 at.% Or more and 40 at.% Or less), or FePt (the ratio of Pt is 40 at.% Or more and 60 at.% Or less).

FIG. 4E is a schematic perspective view showing another bias layer of the first embodiment.
The bias layer 40e shown in FIG. 4E includes a first bias magnetic layer 41a, a second bias magnetic layer 41b, a separation layer 43, and a first magnetic coupling layer 44a. A separation layer 43 is provided between the second magnetic layer 20 and the second bias magnetic layer 41b. A first bias magnetic layer 41a is provided between the separation layer 43 and the second bias magnetic layer 41b. A first magnetic coupling layer 44a is provided between the first bias magnetic layer 41a and the second bias magnetic layer 41b.

  As shown in FIG. 4E, even when the bias pinning layer 42 is not provided, a plurality of bias magnetic layers may be provided via the magnetic coupling layer. By providing a plurality of bias magnetic layers through the magnetic coupling layer and coupling the magnetizations of the plurality of bias magnetic layers in antiparallel, the leakage magnetic field can be suppressed to the outside.

FIG. 5A and FIG. 5B are schematic perspective views showing the difference in the bias direction of the embodiment.
FIG. 5A shows a state in which the magnetization of the first bias magnetic layer 41 a is parallel (0 °) to the bias direction applied from the first bias magnetic layer to the second magnetic layer 20. FIG. 5B shows a state in which the magnetization of the first bias magnetic layer 41 a is in a direction antiparallel to the bias direction applied from the first bias magnetic layer to the second magnetic layer 20.

  The strain sensing element shown in FIGS. 5A and 5B includes the bias layer 40b described above with reference to FIG. 4B. An arrow 41am shown in FIGS. 5A and 5B represents the magnetization of the first bias magnetic layer 41a. An arrow 41bm shown in FIGS. 5A and 5B represents the magnetization of the second bias magnetic layer 41b. An arrow 20p shown in FIGS. 5A and 5B represents the direction of the bias applied to the second magnetic layer 20.

  As shown in FIG. 5A, when the separation layer 43 uses a configuration that provides positive magnetic coupling, the magnetization 41am of the first bias magnetic layer 41a adjacent to the second magnetic layer 20 via the separation layer 43. The bias 20p is applied to the second magnetic layer 20 in a direction parallel to the second magnetic layer 20. As shown in FIG. 5B, when the separation layer 43 has a negative magnetic coupling, the magnetization 41 am of the first bias magnetic layer 41 a adjacent to the second magnetic layer 20 through the separation layer 43. A bias 20p is applied to the second magnetic layer 20 in the antiparallel direction.

  Whether the magnetic coupling is positive magnetic coupling or negative magnetic coupling is determined by the material included in the separation layer 43 and the thickness of the material. When the RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling is positive at the thickness of each material, a positive magnetic coupling occurs. When the RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling is negative at the thickness of each material, a negative magnetic coupling occurs.

  As a material used for the separation layer 43, for example, Cu, Ru, Rh, Ir, V, Cr, Nb, Mo, Ta, W, Rr, or the like exhibiting RKKY bonding is used. With respect to these elements, positive magnetic coupling and negative magnetic coupling can be selectively used according to the thickness of the separation layer 43. In addition to these elements, Au, Ag, Pt, Pd, Ti, Zr, Hf, and the like may be used. When these elements are used as the separation layer 43, a positive magnetic coupling is mainly obtained. When negative magnetic coupling is used, Ru, Rh, and Ir can be used.

  If the strength of the bias 20p by the bias layer 40b is too strong, the anisotropic magnetic field of the second magnetic layer 20 (magnetization free layer) becomes too high, and the rotation of the magnetization 20m with respect to strain becomes slow. In order to obtain the effect of improving reversibility and not to reduce the sensitivity of rotation of the magnetization 20m to strain, it is preferable to set the strength of the bias 20p from the bias layer 40b appropriately. In order to moderately control the strength of the bias 20p from the bias layer 40b, it is preferable to use Cu whose exchange coupling constant of RKKY is not extremely high. Cu is preferable because the change in the magnetic coupling with respect to the thickness is gentle and easy to control.

FIG. 6 is a schematic perspective view illustrating another strain sensing element according to the first embodiment.
As shown in FIG. 6, the strain sensing element 100b used in the embodiment includes the first electrode E1, the underlayer 50, the bias layer 40, the second magnetic layer 20, the intermediate layer 30, and the first magnetization. The pinned layer 11, the magnetic coupling layer 13, the second magnetization pinned layer 12, the pinning layer 60, the cap layer 70, and the second electrode E2 are included. The first magnetization fixed layer 11 corresponds to the first magnetic layer 10.

An underlayer 50 is provided between the first electrode E1 and the second electrode E2. A bias layer 40 is provided between the base layer 50 and the second electrode E2. The second magnetic layer 20 is provided between the bias layer 40 and the second electrode E2. An intermediate layer 30 is provided between the second magnetic layer 20 and the second electrode E2. The first magnetization fixed layer 11 is provided between the intermediate layer 30 and the second electrode E2. A magnetic coupling layer 13 is provided between the first magnetization fixed layer 11 and the second electrode E2. The second magnetization fixed layer 12 is provided between the magnetic coupling layer 13 and the second electrode E2. A pinning layer 60 is provided between the second magnetization fixed layer 12 and the second electrode E2. A cap layer 70 is provided between the pinning layer 60 and the second electrode E2.
In this example, the strain sensing element 100b has a top spin valve type structure.

For example, Ta / Ru is used for the underlayer 50. The thickness of this Ta layer is 3 nm, for example. The thickness of this Ru layer is 2 nm, for example.
For example, IrMn (7 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Cu (5 nm) is used for the bias layer 40.
For the second magnetic layer 20 (magnetization free layer), for example, Co ₄₀ Fe ₄₀ B ₂₀ (4 nm) is used.
For the intermediate layer 30, for example, an MgO layer having a thickness of 2.0 nm is used.
For the first magnetization fixed layer 11, for example, Co ₄₀ Fe ₄₀ B ₂₀ / Fe ₅₀ Co ₅₀ is used. The thickness of this Co ₄₀ Fe ₄₀ B ₂₀ layer is, for example, 2 nm. The thickness of this Fe ₅₀ Co ₅₀ layer is, for example, 1 nm.
As the magnetic coupling layer 13, for example, a Ru layer having a thickness of 0.9 nm is used.
For the second magnetization fixed layer 12, for example, a Co ₇₅ Fe ₂₅ layer having a thickness of 2.5 nm is used. For the pinning layer 60, for example, an IrMn layer having a thickness of 7 nm is used.
Ta / Ru is used for the cap layer. The thickness of this Ta layer is 1 nm, for example. The thickness of this Ru layer is 5 nm, for example.

  In the example described above, the structure of the bias layer 40 has the structure of the bias layer 40b shown in FIG. When the bias layer 40 is formed below the second magnetic layer 20 (magnetization free layer) (−Z-axis direction) by the top spin valve, the structure of the bias layer 40b shown in FIG. An inverted structure can be used. For each of the layers included in the strain sensing element 100b, for example, the materials described with respect to the strain sensing element 100a illustrated in FIG. 3 can be used.

FIG. 7 is a schematic perspective view illustrating another strain sensing element according to the first embodiment.
As shown in FIG. 7, the strain sensing element 100c used in the embodiment includes the first electrode E1, the underlayer 50, the pinning layer 60, the first magnetic layer 10, the intermediate layer 30, and the second magnetic material. The layer 20, the bias layer 40, the cap layer 70, and the second electrode E2 are included. An underlayer 50 is provided between the first electrode E1 and the second electrode E2. A pinning layer 60 is provided between the foundation layer 50 and the second electrode E2. The first magnetic layer 10 (reference layer) is provided between the pinning layer 60 and the second electrode E2. An intermediate layer 30 is provided between the first magnetic layer 10 and the second electrode E2. The second magnetic layer 20 is provided between the intermediate layer 30 and the second electrode E2. A bias layer 40 is provided between the second magnetic layer 20 and the second electrode E2. A cap layer 70 is provided between the bias layer 40 and the second electrode E2.

  In the strain sensing elements 100a and 100b already described, a structure using the first magnetization fixed layer 11, the magnetic coupling layer 13, and the second magnetization fixed layer 12 is applied. In the strain sensing element 100c shown in FIG. 7, a single pin structure using a single magnetization fixed layer is applied.

For example, Ta / Ru is used for the underlayer 50. The thickness of this Ta layer is 3 nm, for example. The thickness of this Ru layer is 2 nm, for example.
For the pinning layer 60, for example, an IrMn layer having a thickness of 7 nm is used.
For the first magnetic layer (reference layer), for example, a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used.
For the intermediate layer 30, for example, an MgO layer having a thickness of 2.0 nm is used.
For the second magnetic layer 20 (magnetization free layer), for example, Co ₄₀ Fe ₄₀ B ₂₀ (4 nm) is used.
For the bias layer 40, Cu (5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm) is used.
Ta / Ru is used for the cap layer 70. The thickness of this Ta layer is 1 nm, for example. The thickness of this Ru layer is 5 nm, for example.

  In the example described above, the structure of the bias layer 40 has the structure of the bias layer 40b shown in FIG. For each of the layers included in the strain sensing element 100c, for example, the materials described with respect to the strain sensing element 100a illustrated in FIG. 3 can be used.

FIG. 8A to FIG. 8F are schematic cross-sectional views showing the magnetization fixed direction of the magnetization fixed layer, the magnetization fixed direction of the bias magnetic layer, and the bias direction applied to the magnetization free layer.
FIG. 8A to FIG. 8C illustrate the strain sensing element 100a illustrated in FIG.
8D to 8E illustrate the strain sensing element 100c illustrated in FIG.
In FIG. 8A to FIG. 8F, the case where the magnetic coupling through the separation layer 43 is positive will be described as an example.

FIG. 8A shows an example in which the bias layer 40a shown in FIG. 4A is provided.
The bias layer 40a shown in FIG. 8A includes a single bias magnetic layer (first bias magnetic layer 41a). In FIG. 8A, the laminated body in which the magnetization 12m of the second magnetization fixed layer 12, the magnetization 11m of the first magnetization fixed layer 11, and the magnetization 41am of the first bias magnetic layer 41a becomes the strain sensing element 100d. An example is shown in which a single heat treatment in a magnetic field is performed after molding. FIG. 8A shows an example in which the heat treatment in a magnetic field is performed by applying a magnetic field in the right direction on the paper (X-axis direction).

  By performing the heat treatment in the magnetic field rightward on the paper surface, the magnetization 12m of the second magnetization fixed layer 12 in contact with the pinning layer 60 is fixed rightward (X-axis direction). At the same time, the magnetization 41am of the first bias magnetic layer 41a in contact with the bias pinning layer 42 is fixed to the right. The first magnetization fixed layer 11 adjacent to the second magnetization fixed layer 12 via the magnetic coupling layer 13 is magnetically coupled antiparallel to the second magnetization fixed layer 12 via the magnetic coupling layer 13. Therefore, the magnetization 11m of the first magnetization fixed layer 11 is fixed to the left. As a result, in the strain sensing element 100d shown in FIG. 8A, the direction of the bias 20p applied from the first bias magnetic layer 41a to the second magnetic layer 20 (magnetization free layer) is rightward, and the first magnetization fixed layer 11 is a direction antiparallel to the fixing direction of the magnetization 11m.

FIG. 8B shows an example in which the bias layer 40b shown in FIG. 4B is provided.
The bias layer 40b shown in FIG. 8B includes two bias magnetic layers (a first bias magnetic layer 41a and a second bias magnetic layer 41b). The strain sensing element 100d shown in FIG. 8A includes a single bias magnetic layer (first bias magnetic layer 41a), whereas the strain sensing element 100e shown in FIG. A bias magnetic layer (first bias magnetic layer 41a and second bias magnetic layer 41b). Therefore, the magnetization 41am of the first bias magnetic layer 41a adjacent to the second magnetic layer 20 (magnetization free layer) via the separation layer 43 is fixed to the left (−X axis direction). Thus, a leftward bias 20p is applied to the second magnetic layer 20 (magnetization free layer). Therefore, the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is parallel to the pinning direction of the magnetization 11m of the first magnetization fixed layer 11.

FIG. 8C shows an example in which the bias layer 40c shown in FIG. 4C is provided.
The bias layer 40c shown in FIG. 8C includes three bias magnetic layers (a first bias magnetic layer 41a, a second bias magnetic layer 41b, and a third bias magnetic layer 41c). The strain sensing element 100d illustrated in FIG. 8A includes a single bias magnetic layer (first bias magnetic layer 41a), whereas the strain sensing element 100f illustrated in FIG. A bias magnetic layer (first bias magnetic layer 41a, second bias magnetic layer 41b, and third bias magnetic layer 41c). The odd number of bias magnetic layers of the strain sensing element 100f shown in FIG. 8C is the same as the odd number of bias magnetic layers of the strain sensing element 100d shown in FIG. 8A. It is. Therefore, the magnetization 41am of the first bias magnetic layer 41a adjacent to the second magnetic layer 20 (magnetization free layer) via the separation layer 43 is fixed to the right. A rightward bias 20p is applied to the second magnetic layer 20 (magnetization free layer). Therefore, the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is antiparallel to the pinning direction of the magnetization 11m of the first magnetization fixed layer 11.

  In the example described above with reference to FIGS. 8A to 8C, the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is set to the first magnetization fixed according to the number of bias magnetic layers. It is selected to be either parallel or anti-parallel to the magnetization 11m of the layer 11. Here, the improvement of the anisotropic magnetic field of the second magnetic layer 20 (magnetization free layer) by the bias layer 40 is performed regardless of whether the direction of the bias 20p is parallel to the magnetization 11m of the first magnetization fixed layer 11 or antiparallel. Either can be obtained. And a gauge factor can be improved.

  In the case of the tunnel-type strain sensing element 100 in which an insulating layer is used for the intermediate layer 30, the direction of the bias 20 p is more preferably antiparallel to the direction of the magnetization 11 m of the first magnetization fixed layer 11. The reason will be described later. That is, when the bias layer 40 is provided in the synthetic pin type strain sensing elements 100a and 100b including the two magnetization fixed layers (the second magnetization fixed layer 12 and the first magnetization fixed layer 11), the bias layer 40 includes the bias layer 40. More preferably, the number of bias magnetic layers is an odd number.

FIG. 8D shows an example in which the bias layer 40a shown in FIG.
The bias layer 40a shown in FIG. 8D includes a single bias magnetic layer (first bias magnetic layer 41a). In FIG. 8D, an example in which the magnetization 10m of the first magnetic layer 10 and the magnetization 41am of the first bias magnetic layer 41a are fixed by a single heat treatment in a magnetic field after forming the laminated body that becomes the strain sensing element 100g. Indicates. FIG. 8D shows an example in which the heat treatment in a magnetic field is performed by applying a magnetic field in the right direction (X-axis direction) on the paper surface.

  By performing heat treatment in the magnetic field rightward on the paper, the magnetization 10m of the first magnetic layer 10 in contact with the pinning layer 60 is fixed rightward (X-axis direction). At the same time, the magnetization 41am of the first bias magnetic layer 41a in contact with the bias pinning layer 42 is fixed to the right. As a result, in the strain sensing element 100g shown in FIG. 8D, the direction of the bias 20p applied from the first bias magnetic layer 41a to the second magnetic layer 20 (magnetization free layer) is rightward, and the first magnetic layer 10 The direction is parallel to the fixing direction of the magnetization of 10 m.

FIG. 8E shows an example in which the bias layer 40b shown in FIG. 4B is provided.
The bias layer 40b shown in FIG. 8E includes two bias magnetic layers (a first bias magnetic layer 41a and a second bias magnetic layer 41b). The strain sensing element 100g shown in FIG. 8D includes a single bias magnetic layer (first bias magnetic layer 41a), whereas the strain sensing element 100h shown in FIG. A bias magnetic layer (first bias magnetic layer 41a and second bias magnetic layer 41b). Therefore, the magnetization 41am of the first bias magnetic layer 41a adjacent to the second magnetic layer 20 (magnetization free layer) via the separation layer 43 is fixed to the left (−X axis direction). Thus, a leftward bias 20p is applied to the second magnetic layer 20 (magnetization free layer). Accordingly, the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is antiparallel to the fixing direction of the magnetization 10m of the first magnetic layer 10.

FIG. 8F shows an example in which the bias layer 40c shown in FIG. 4C is provided.
The bias layer 40c shown in FIG. 8F includes three bias magnetic layers (a first bias magnetic layer 41a, a second bias magnetic layer 41b, and a third bias magnetic layer 41c). The strain sensing element 100g shown in FIG. 8D includes a single bias magnetic layer (first bias magnetic layer 41a), whereas the strain sensing element 100i shown in FIG. A bias magnetic layer (first bias magnetic layer 41a, second bias magnetic layer 41b, and third bias magnetic layer 41c). The odd number of bias magnetic layers of the strain sensing element 100i shown in FIG. 8F is the same as the odd number of bias magnetic layers of the strain sensing element 100g shown in FIG. 8D. It is. Therefore, the magnetization 41am of the first bias magnetic layer 41a adjacent to the second magnetic layer 20 (magnetization free layer) via the separation layer 43 is fixed to the right. A rightward bias 20p is applied to the second magnetic layer 20 (magnetization free layer). Therefore, the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is parallel to the fixing direction of the magnetization 10m of the first magnetic layer 10.

  As shown in FIGS. 8D to 8F, in the case of using a single pinned pinned layer, when the number of bias magnetic layers included in the bias layer 40 is an even number, the direction of the bias 20p is The first magnetic layer 10 in contact with the intermediate layer 30 is antiparallel to the direction of the magnetization 10 m.

  Thus, when the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is anti-parallel to the magnetization fixed layer in contact with the intermediate layer 30 of the first magnetic layer 10, the first magnetic When the number of magnetization fixed layers of the layer 10 is an even number, the number of bias magnetic layers included in the bias layer 40 is an odd number. On the other hand, when the number of magnetization fixed layers of the first magnetic layer 10 is an odd number, the number of bias magnetic layers included in the bias layer 40 is an even number.

When the direction of the bias 20p applied to the second magnetic layer 20 (magnetization free layer) is parallel to the magnetization fixed layer in contact with the intermediate layer 30 of the first magnetic layer 10, the magnetization of the first magnetic layer 10 is fixed. When the number of layers is an even number, the number of bias magnetic layers included in the bias layer 40 is an even number. On the other hand, when the number of magnetization fixed layers of the first magnetic layer 10 is an odd number, the number of bias magnetic layers included in the bias layer 40 is an odd number.
The bias layer may include four or more bias magnetic layers.

As a first example according to the embodiment, a strain sensing element 100 having the following structure is manufactured.
(First embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Pinning layer 60: Ir ₂₂ Mn ₇₈ (7 nm)
Second magnetization fixed layer 12: Co ₇₅ Fe ₂₅ (2.5 nm)
Magnetic coupling layer 13: Ru (0.9 nm)
First magnetization fixed layer 11: Co ₄₀ Fe ₄₀ B ₂₀ (3 nm)
Intermediate layer 30: MgO (2 nm)
Second magnetic layer 20 (magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Bias layer 40: Cu (5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm)
Cap layer 70: Cu (1 nm) / Ta (2 nm) / Ru (5 nm)
The structure of the strain sensing element 100 of the first embodiment is the same as the structure of the strain sensing element 100a shown in FIG. The structure of the bias layer 40 is the same as the structure of the bias layer 40b shown in FIG. That is, the bias layer 40 of the first embodiment has a structure of separation layer 43 / first bias magnetic layer 41a / first magnetic coupling layer 44a / second bias magnetic layer 41b / bias pinning layer.

As a first comparative example, a strain sensing element having the following structure is manufactured.
(Comparative Example 1)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Pinning layer 60: Ir ₂₂ Mn ₇₈ (7 nm)
Second magnetization fixed layer 12: Co ₇₅ Fe ₂₅ (2.5 nm)
Magnetic coupling layer 13: Ru (0.9 nm)
First magnetization fixed layer 11: Co ₄₀ Fe ₄₀ B ₂₀ (3 nm)
Intermediate layer 30: MgO (2 nm)
Second magnetic layer 20 (magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Cap layer 70: Cu (10 nm) / Ta (2 nm) / Ru (5 nm)
In the first comparative example, the bias layer 40 is not provided.
The laminated body of the first example and the laminated body of the first comparative example are annealed after molding in a magnetic field of 6500 oersted (Oe) at 320 ° C. and 1 H. Thereby, the magnetization 12m of the second magnetization fixed layer 11 and the magnetization 11m of the first magnetization fixed layer 11 are fixed. In the first embodiment, the magnetization 41am of the first bias magnetic layer 41a and the magnetization 41bm of the second bias magnetic layer 41b are fixed.

FIG. 9A to FIG. 9D are graphs showing examples of results of magnetic characteristics before element processing of the laminates of the first example and the first comparative example.
FIG. 9A shows an example of a BH loop in which the case where a magnetic field is applied in the direction in which the heat treatment in a magnetic field is performed is evaluated as a positive magnetic field in the first embodiment. FIG. 9B shows an example of a BH loop evaluated in the first embodiment by applying a magnetic field in the direction perpendicular to the heat treatment direction in the magnetic field and in the plane. FIG. 9C illustrates an example of a BH loop in which a case where a magnetic field is applied in a direction in which heat treatment in a magnetic field is performed is evaluated as a positive magnetic field in the first comparative example. FIG. 9D shows an example of a BH loop evaluated in the first comparative example by applying a magnetic field in the direction perpendicular to the heat treatment direction in the magnetic field and in the plane.

In the BH loop shown in FIG. 9A, a loop shape of an easy magnetization axis with good squareness is obtained. In the BH loop shown in FIG. 9B, a loop shape with a typical hard axis is obtained. From this result, it is understood that in-plane induced magnetic anisotropy is obtained in the second magnetic layer 20 (magnetization free layer) with the heat treatment direction in the magnetic field as the easy axis. From the BH loop shown in FIG. 9A, the hysteresis loop of the second magnetic layer 20 (magnetization free layer) confirms H _shift of 4.7 Oe in the positive magnetic field direction. This is because a bias 20p is applied to the negative magnetic field side by the bias layer 40, so that a positive magnetic field of 4.7 Oe is required to reverse the second magnetic layer 20 (magnetization free layer). Means. The anisotropic magnetic field H _k calculated from the BH loop shown in FIG. 9B, which is related to the strength of the induced magnetic anisotropy, is estimated to be 22.5 Oe. Thereby, it is confirmed that the anisotropic magnetic field is improved by providing the bias layer 40 with respect to the first comparative example. Coercivity _{H c} estimated from BH loop shown in FIG. 9 (a) is a 3.7Oe. The magnetostriction constant is 20 ppm. About a magnetostriction constant, the value equivalent to a 1st comparative example is estimated.

In the BH loop shown in FIG. 9C, a loop shape of an easy magnetization axis with good squareness is obtained. In the BH loop shown in FIG. 9D, a typical loop shape of a hard axis is obtained. From this result, it is understood that in-plane induced magnetic anisotropy is obtained in the second magnetic layer 20 (magnetization free layer) with the heat treatment direction in the magnetic field as the easy axis. The anisotropy magnetic field H _k calculated from the BH loop shown in FIG. 9D, which is related to the strength of the induced magnetic anisotropy, is estimated to be 18.3 Oe. From BH loop shown in FIG. 9 (c), the coercive force _{H c} of the second magnetic layer 20 (free magnetic layer) of the first comparative example is estimated to 3.7Oe. The coercive force _Hc is a characteristic index indicating the ease of magnetization rotation. Coercivity H _c of 3.7Oe, the magnetization rotation by the reverse magnetostrictive effect can be said to likely value sufficiently. As a result of evaluating the magnetostriction constant of the first comparative example, the magnetostriction constant is 20 ppm. This value can be said to be a sufficiently high value to cause magnetization rotation with respect to strain.

From the results of FIGS. 9A to 9D, the configuration of the second magnetic layer 20 (magnetization free layer) of the first example is the same as that of the second magnetic layer 20 (magnetization free layer) of the first comparative example. ). Coercivity H _c of the first embodiment is substantially the same as the coercive force H _c of the first comparative example. The magnetostriction constant of the first example is substantially the same as the magnetostriction constant of the first comparative example. On the other hand, in the first example, it can be seen that by providing the bias layer 40, the anisotropic magnetic field _Hk is improved as compared with the first comparative example.

  The laminated bodies of the first example 1 and the first comparative example are processed into vertical energization elements by photolithography and milling. The element size of the vertical energization element is 20 μm × 20 μm.

FIG. 10A to FIG. 10E are graphs showing examples of results of strain sensor characteristics of the strain sensing element 100 of the first embodiment.
The evaluation of the strain sensor characteristics shown in FIGS. 10A to 10E is performed by the substrate bending method. Strain is applied to a wafer (strip wafer) obtained by cutting the wafer of the strain sensing element 100 to be prototyped into a strip shape by a four-point bending method using a knife edge. A load cell is incorporated in a knife edge that bends the strip wafer, and a strain applied to the strain sensing element 100 on the wafer surface is calculated by a load measured by the load cell. For the calculation of strain, a general theoretical formula of a two-side support beam represented by the following formula is used.

In formula 1, e _s represents the Young's modulus of the wafer. L ₁ represents the edge-to-edge length of the outer knife edge. L ₂ represents an edge length between the inner knife edge. W represents the width of the strip wafer. t represents the thickness of the strip wafer. G represents the load applied to the knife edge. The load applied to the knife edge can be continuously changed by motor control.

  The direction of strain application is applied in a direction perpendicular to the direction of the magnetization 11m of the first magnetization fixed layer 11 in the same plane. In the present specification, a positive value strain is a tensile strain, and a negative value strain is a compressive strain.

  In the example shown in FIG. 10A, with respect to the strain sensing element 100 of the first embodiment having an element size of 20 μm × 20 μm, the strain applied to the strain sensing element 100 is −0.8 (% 0) or more and 0.8. Between (% 0) and below, it is set as a fixed value in increments of 0.2 (% 0). FIG. 10A shows an example of the result of measuring the magnetic field dependence of electrical resistance at each strain. The external magnetic field direction at the time of measurement is applied in a direction parallel to the second magnetization fixed layer 12 in a plane. The positive external magnetic field is a case where a magnetic field is applied to the opposite side to the magnetization 12 m of the second magnetization fixed layer 12. FIG. 10A shows that the RH loop shape changes depending on the value of applied strain. This indicates that the in-plane magnetic anisotropy of the second magnetic layer 20 (magnetization free layer) is changed by the inverse magnetostriction effect.

  FIG. 10B to FIG. 10E show the strain sensing element 100 of the first embodiment with an external magnetic field fixed and a strain of −0.8 (% 0) to 0.8 (% 0). The change of the electrical resistance when sweeping continuously between is shown. The distortion is swept from −0.8 (% 0) to 0.8 (% 0), and then from 0.8 (% 0) to −0.8 (% 0). These results show the strain sensor characteristics. In FIG. 10B, evaluation is performed by applying an external magnetic field of 15 Oe. In FIG. 10C, the evaluation is performed by applying an external magnetic field of 10 Oe. In FIG. 10D, the evaluation is performed by applying an external magnetic field of 7.5 Oe. In FIG. 10E, an evaluation is performed by applying an external magnetic field of 5 Oe.

  In the strain sensing element 100 of the embodiment, a high gauge factor can be obtained by applying an appropriate bias magnetic field. The external magnetic field can also be applied by providing a hard bias described later on the side wall of the strain sensing element 100. In the strain sensing element 100 of the first embodiment, an external magnetic field is simply applied by a coil for evaluation. From FIG. 10B to FIG. 10E, the gauge factor in each bias magnetic field of the first embodiment is estimated from the change in electrical resistance with respect to strain.

The gauge factor is expressed by the following equation.

GF = (dR / R) / dε Equation (2)

As shown in FIG. 10B, in the first embodiment, the gauge factor when the external magnetic field is 15 Oe is 1642. From FIG. 10C, in the first example, the gauge factor when the external magnetic field is 10 Oe is 2147. From FIG. 10D, in the first embodiment, the gauge factor when the external magnetic field is 7.5 Oe is 3063.

  On the other hand, as shown in FIG. 10E, when the external magnetic field is 6 Oe, the strain is swept from −0.8 (% 0) to 0.8 (% 0). The change in electrical resistance when sweeping from 8 (% 0) to -0.8 (% 0) is irreversible. From this result, in the first example, the maximum gauge factor (3063) is obtained when the bias magnetic field is 7.5 Oe.

Fig.11 (a)-FIG.11 (e) are graphs which show the example of the strain sensor evaluation result of the strain sensing element of a 1st comparative example.
In the example shown in FIG. 11A, the strain applied to the strain sensing element is −0.8 (% 0) or more and 0.8 (%) for the strain sensing element of the first comparative example having an element size of 20 μm × 20 μm. 0) is set as a fixed value in increments of 0.2 (% 0) between the following. FIG. 11A shows examples of results obtained by measuring the magnetic field dependence of electrical resistance at each strain. 11A also shows that the RH loop shape changes depending on the value of applied strain, as in FIG. 10A. This indicates that the in-plane magnetic anisotropy of the second magnetic layer 20 (magnetization free layer) is changed by the inverse magnetostriction effect.

  FIG. 11B to FIG. 11E show the detection element of the first comparative example with an external magnetic field fixed and a strain between −0.8 (% 0) and 0.8 (% 0). Shows the change in electrical resistance when sweeping continuously. In FIG. 11B, evaluation is performed by applying an external magnetic field of 15 Oe. In FIG. 11C, evaluation is performed by applying an external magnetic field of 10 Oe. In FIG. 11D, the evaluation is performed by applying an external magnetic field of 7.5 Oe. In FIG. 11E, the evaluation is performed by applying an external magnetic field of 5 Oe.

  From FIG. 11B, in the first comparative example, the gauge factor when the external magnetic field is 15 Oe is 1357. From FIG. 11C, in the first comparative example, the gauge factor when the external magnetic field is 10 Oe is 1580. As shown in FIG. 11D, the gauge factor when the external magnetic field is 7.5 Oe is 2087.

  On the other hand, as shown in FIG. 11 (e), when the external magnetic field is 5 Oe, sweeping is performed from −0.8 (% 0) to 0.8 (% 0), and then 0.8 (% 0). ) To −0.8 (% 0), the change in electrical resistance is irreversible. From this result, in the first example, the maximum gauge factor (2087) is obtained when the bias magnetic field is 7.5 Oe.

  From the results of FIGS. 10A to 10E and FIGS. 11A to 11E, the first example in which the bias layer 40 is provided is compared with the first comparative example. A high gauge factor is confirmed.

FIG. 12 is a graph showing examples of evaluation results of gauge factors in various bias magnetic fields.
In order to consider the results described above with respect to FIGS. 10 (a) -10 (e) and 11 (a) -11 (e), various bias magnetic fields are used for the first example and the first comparative example. Use to evaluate the gauge factor. The horizontal axis of the graph of FIG. 12 represents the difference between the bias magnetic field used for evaluation and the H _shift of the RH loop at zero strain in FIGS. 10 (a) and 11 (a).

In the strain sensing element 100 according to the embodiment, a relatively high gauge factor can be obtained in a magnetic field that is relatively close to the center position (H _shift position) of the hysteresis loop of the RH loop at zero strain. This can be seen from the shape of the RH loop evaluated by applying different strains, as shown in FIGS. 10 (a) and 11 (a). That is, a higher gauge factor can be obtained by applying a bias magnetic field that reduces H-H _shift .

As can be seen from the curve CL2 shown in FIG. 12, in the first comparative example, the maximum value (2087) of the gauge factor is obtained when H-H _shift is around 5.5 Oe. With a bias magnetic field of 5.5 Oe or less, the magnetization movement of the second magnetic layer with respect to strain becomes irreversible. On the other hand, as can be seen from the curve CL1 shown in FIG. 12, in the first embodiment, reversible strain sensor characteristics are obtained when H-H _shift is around 1.5 Oe. As a result, the maximum gauge factor (3063) is obtained when H-H _shift is around 1.5 Oe. The maximum value (3063) of the gauge factor of the first example is larger than the maximum value (2087) of the gauge factor of the first comparative example. Thus, by providing the bias layer 40, it is confirmed that the bias magnetic field that can provide reversible strain sensor characteristics can be reduced, and the gauge factor is improved.

The principle that the reversibility of the strain sensor characteristics can be improved by providing the bias layer 40 will be described with reference to the drawings.
FIG. 13A to FIG. 13F are schematic views showing the in-plane angle dependence of the free energy of the magnetization free layer of the embodiment.
FIG. 14A to FIG. 14F are schematic views showing the in-plane angle dependence of the free energy of the magnetization free layer of the comparative example.

  13 (a), 13 (c), 13 (e), 14 (a), 14 (c) and 14 (e) show the in-plane angle dependence of the free energy of the magnetization free layer. FIG. FIG. 13B, FIG. 13D, FIG. 13F, FIG. 14B, FIG. 14D, and FIG. 14F show the magnetization of the magnetization free layer and the strain generated in the magnetization free layer. Illustrate.

  In the examples shown in FIGS. 13A to 13F and FIGS. 14A to 14F, the direction parallel to the magnetization 10m of the first magnetic layer 10 (magnetization fixed layer) is defined as 0 °. The antiparallel direction is defined as 180 °. As described with reference to FIGS. 9A to 9D, the second magnetic layer 20 (magnetization free layer) has an easy magnetization axis in the directions of 0 ° and 180 ° due to induced magnetic anisotropy by heat treatment in a magnetic field. It has an in-plane magnetic anisotropy with MA1 and 90 ° and 270 ° as the hard axis MA2. This is because, as shown in FIG. 13A, when the relative angle between the magnetization 10m of the first magnetic layer 10 and the magnetization 20m of the second magnetic layer 20 is 90 ° (or 270 °), 2 means that the free energy of the magnetic layer 20 (magnetization free layer) has a maximum distribution.

  As shown in FIGS. 13A and 13B, the initial magnetization 20mf of the second magnetic layer 20 (magnetization free layer) is set to 180 °. With reference to FIGS. 13C to 13F, the state of rotation of the magnetization 20m due to a change in free energy when stress is applied to the second magnetic layer 20 will be described. When a tensile stress ts is applied in the 90 ° (or 270 °) direction so that the curve CL3 shown in FIG. 13C changes to the curve CL4, the free energy increases due to magnetostrictive energy in the 0 ° and 180 ° directions. Occur. Then, the magnetization 20m of the second magnetic layer 20 changes from 180 ° to 90 ° (or 270 °).

FIGS. 13 (a) and 13 (b) in the peak of the energy distribution of the induced magnetic anisotropy indicated by curve CL3 height PH1 is proportional to the anisotropy field _{H k} as described above. As shown in FIGS. 13A, 13C, and 13E, when the anisotropic magnetic field H _k is large to some extent, the peak of the energy distribution of induced magnetic anisotropy near 90 °. The height PH1 is sufficiently large. Therefore, the magnetization 20m of the second magnetic layer 20 that has changed from 180 ° to around 90 ° due to the tensile stress ts tends to return to 180 ° when the tensile stress ts is removed. That is, the reversibility of the electrical resistance change with respect to strain is increased.

On the other hand, as shown in FIG. 14C, when the anisotropic magnetic field _Hk is low, the magnetization 20m of the second magnetic layer 20 has a high peak of the energy distribution of induced magnetic anisotropy near 90 °. It has a component that passes through PH2 and goes to 0 ° without returning to 180 ° after removing the tensile stress ts. This corresponds to the situation described with reference to FIGS. 10 (e), 11 (e) and 12 where the change in electrical resistance is irreversible with respect to strain.

Compare, magnetostriction constant of the first embodiment with an improved anisotropy field H _k is provided a bias layer 40, the coercivity H _c and MR change between the first embodiment and the first comparative example rate magnetostriction constant of the first comparative example, in spite of the respective coercivity H _c and MR ratio equal, the gauge factor of the first embodiment has a high value is 13 ( a) to based on the principle described in FIG. That is, the gauge factor of the first embodiment has a high value, depending on the improvement of the anisotropy field H _k, presumably because reversible strain sensor characteristics can be obtained even without extra bias magnetic field .

As the second to fourth examples according to the embodiment, a strain sensing element 100 having the following structure is manufactured.
(Second embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Pinning layer 60: Ir ₂₂ Mn ₇₈ (7 nm)
Second magnetization fixed layer 12: Co ₇₅ Fe ₂₅ (2.5 nm)
Magnetic coupling layer 13: Ru (0.9 nm)
First magnetization fixed layer 11: Co ₄₀ Fe ₄₀ B ₂₀ (3 nm)
Intermediate layer 30: MgO (2 nm)
Second magnetic layer 20 (magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Bias layer 40: Cu (2.4 nm to ₅ nm) / Fe ₅₀ Co ₅₀ (3 nm) / IrMn (7 nm)
Cap layer 70: Cu (1 nm) / Ta (2 nm) / Ru (5 nm)
(Third embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Pinning layer 60: Ir ₂₂ Mn ₇₈ (7 nm)
Second magnetization fixed layer 12: Co ₇₅ Fe ₂₅ (2.5 nm)
Magnetic coupling layer 13: Ru (0.9 nm)
First magnetization fixed layer 11: Co ₄₀ Fe ₄₀ B ₂₀ (3 nm)
Intermediate layer 30: MgO (2 nm)
Second magnetic layer 20 (magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Bias layer 40: Cu (2.4 nm to ₅ nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm)
Cap layer 70: Cu (1 nm) / Ta (2 nm) / Ru (5 nm)
(Fourth embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Pinning layer 60: Ir ₂₂ Mn ₇₈ (7 nm)
Second magnetization fixed layer 12: Co ₇₅ Fe ₂₅ (2.5 nm)
Magnetic coupling layer 13: Ru (0.9 nm)
First magnetization fixed layer 11: Co ₄₀ Fe ₄₀ B ₂₀ (3 nm)
Intermediate layer 30: MgO (2 nm)
Second magnetic layer 20 (magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Bias layer 40: Cu (2.4 nm to ₅ nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (4 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm)
Cap layer 70: Cu (1 nm) / Ta (2 nm) / Ru (5 nm)
The structure of the strain sensing element 100 of the third embodiment is the same as the structure of the strain sensing element 100a shown in FIG. 3 as in the first embodiment. The structure of the bias layer 40 is the same as the structure of the bias layer 40b shown in FIG. That is, the bias layer 40 of the third embodiment has a structure of separation layer 43 / first bias magnetic layer 41a / first magnetic coupling layer 44a / second bias magnetic layer 41b / bias pinning layer.

  The structure of the strain sensing element 100 of the second embodiment is the same as the structure of the strain sensing element 100a shown in FIG. The structure of the bias layer 40 is the same as the structure of the bias layer 40a shown in FIG. In other words, the bias layer 40 of the second embodiment has a structure of separation layer 43 / first bias magnetic layer 41a / bias pinning layer.

  The structure of the strain sensing element 100 of the fourth embodiment is the same as the structure of the strain sensing element 100a shown in FIG. The structure of the bias layer 40 is the same as the structure of the bias layer 40c shown in FIG. That is, the bias layer 40 of the fourth embodiment includes the separation layer 43 / first bias magnetic layer 41a / first magnetic coupling layer 44a / second bias magnetic layer 41b / second magnetic coupling layer 44b / third bias magnetic layer. 41c / bias pinning layer 42.

  About the laminated body of the strain sensing element 100 of the 2nd-4th Example, the thickness of Cu of the separation layer 43 is changed, and a several laminated body is created in each of the 2nd-4th Example. Thereafter, similarly to the results shown in FIGS. 9A to 9D, the magnetic characteristics before element processing are evaluated.

FIG. 15A to FIG. 15D are graphs showing examples of results of magnetic characteristics before element processing of the laminated bodies of the second to fourth examples.
FIG. 15A shows a similar analysis by the method shown in FIGS. 9A to 9D, estimates H _shift and H _k , uses H _shift as the horizontal axis, and H _k as the vertical axis. Shows an example of the results plotted.

  In FIG. 15A, the results of the first comparative example in which the bias layer 40 is not provided are plotted together. In FIG. 15A, the result of the third example is represented by “■”. In FIG. 15A, the result of the second example is represented by “♦”. In FIG. 15A, the result of the fourth embodiment is represented by “「 ”. In FIG. 15A, the result of the first comparative example is represented by “◯”.

As can be seen from FIG. 15A, in the second and fourth embodiments having an odd number of bias magnetic layers, H _shift is negative. It can be seen that in the third embodiment having an even number of bias magnetic layers, H _shift is positive. In the second to fourth embodiments, a stacked body having H _shift having different absolute values is realized by changing the Cu thickness of the separation layer 43. In each of the second to fourth embodiments, H _shift having a larger absolute value is confirmed as the Cu thickness of the separation layer 43 is smaller.

FIG. 15A shows that the anisotropic magnetic field is improved as the absolute value of H _shift is increased. This result, by adjusting the thickness of the Cu of the separation layer 43, it is understood that it is possible to control the increase of the anisotropy field H _k. Here, when improving the anisotropy field H _k, while the reversible magnetization 20m of the second magnetic layer 20 with respect to strain is improved, when imparting unnecessarily high anisotropy field H _k, the relative strain 2 The change of the magnetization 20m of the magnetic layer 20 hardly occurs. Therefore, for the improvement of the anisotropy field H _k, and more preferably in the appropriate amount. The anisotropic magnetic field H _k is preferably set to about 20 Oe or more and 30 Oe or less, for example.

FIG. 15B shows an example of a BH loop in which the case where a magnetic field is applied in the direction in which the heat treatment in the magnetic field is applied to Example 2A in which the H _shift of the second embodiment is about −19 Oe is evaluated as a positive magnetic field. Represent.
FIG. 15C illustrates an example of a BH loop in which a case where a magnetic field is applied in the direction in which the heat treatment in a magnetic field is performed is evaluated as a positive magnetic field in the first comparative example.
FIG. 15D shows an example of a BH loop in which the case where a magnetic field is applied in the direction of performing the heat treatment in the magnetic field is evaluated as a positive magnetic field in Example 3A in which the H _shift of the third embodiment is about 18 Oe. .

  First, referring to FIG. 15C of Comparative Example 1, it can be seen that the hysteresis loop of the second magnetic layer 20 (magnetization free layer) is vertically symmetrical and has good squareness. On the other hand, in Example 2A shown in FIG. 15B, the squareness is good on the upper side of the hysteresis loop of the second magnetic layer 20 (magnetization free layer), but the squareness is slightly deviated on the lower side. I understand. This means that the magnetization stability on the side antiparallel to the bias direction applied from the bias layer 40 to the second magnetic layer 20 (magnetization free layer) is slightly reduced. The squareness is broken in Example 2A because, as can be seen from FIG. 8A, when the second magnetic layer 20 (magnetization free layer) is parallel to the first magnetization fixed layer 11, the stability of magnetization is It can be said that it has fallen slightly.

  On the other hand, in Example 3A shown in FIG. 15C, the squareness is good on the lower side of the hysteresis loop of the second magnetic layer 20 (magnetization free layer), while the squareness is slightly deviated on the upper side. I understand. This also means that the magnetization stability on the antiparallel side to the bias direction applied from the bias layer 40 to the second magnetic layer 20 (magnetization free layer) is slightly lowered. The squareness is broken in Example 3A because, as can be seen from FIG. 8B, when the second magnetic layer 20 (magnetization free layer) is antiparallel to the first magnetization pinned layer 11, the stability of magnetization. Can be said to have fallen slightly.

  Here, in the case of a tunnel-type strain sensing element using an insulating layer as the intermediate layer 30, it is more preferable that the direction of the bias 20 p be antiparallel to the magnetization 11 m of the first magnetization fixed layer 11. This is because, in a tunnel type strain sensing element, the relative angle between the pinned layer and the free layer changes between 90 ° and 180 °, rather than between 0 ° and 90 °. This is because the change in electric resistance can be greater in this case, and it is easier to obtain a higher gauge factor when driven as a strain sensor between 90 ° and 180 °.

  Therefore, when the bias layer 40 is provided in the synthetic pin type strain sensing element including the two magnetization fixed layers as in the second to fourth embodiments, the number of the bias magnetic layers included in the bias layer 40 is set as follows. An odd number is more preferable. This is because, as described with reference to FIGS. 15A to 15D, the odd bias magnetic layer has better magnetization stability in the antiparallel direction to the first magnetization fixed layer 11. .

However, even when an even number of bias magnetic layers are used, the thickness of Cu in the separation layer 43 is made appropriate, and the absolute value of H _shift is not too large so that the magnetization stability in the antiparallel direction is stabilized. It is possible to keep without breaking the nature.
The direction of the bias applied from the bias layer 40 to the second magnetic layer (magnetization free layer) is preferably 180 ° with respect to the direction of fixation of the magnetization 11 m of the first magnetization fixed layer 11.

FIG. 16A to FIG. 16D are schematic views for explaining another strain sensing element according to the embodiment.
In the embodiment described above, the case where the bias direction applied from the bias layer 40c to the second magnetic layer 20 (magnetization free layer) is parallel or anti-parallel to the first magnetization fixed layer 11 has been described. However, the bias direction is not limited to being parallel / antiparallel to the first magnetization fixed layer 11. It is possible to apply a bias in any direction.

  For example, as shown in FIG. 16A, the direction of the bias 20p can be set to 135 ° (or 225 °) with respect to the direction of the magnetization 11m of the first magnetization fixed layer 11. The direction of the bias 20p is set by two-step annealing in a magnetic field as shown in FIGS. 16B and 16C, selection of a material used for the pinning layer 60, and bias biasing layer 42. This is possible depending on the selection of the materials used.

  About the antiferromagnetic material used for the pinning layer 60 or the bias pinning layer 42, the temperature at which magnetization fixation occurs depends on the composition. For example, an ordered alloy-based material such as PtMn has a higher temperature at which magnetization fixation is performed compared to a material that causes magnetization fixation even with irregularities such as IrMn. For example, when PtMn is used for the pinning layer 60 of the strain sensing element 100j shown in FIG. 16A and IrMn is used for the bias pinning layer 42, two stages as shown in FIG. 16B and FIG. Perform heat treatment in a magnetic field. Then, in the 320 ° C.-10H annealing shown in FIG. 16B, the second magnetization fixed layer 12 in contact with the pinning layer 60 is fixed to the right. The third bias magnetic layer 41c in contact with the bias pinning layer 42 is once fixed to the right.

  Thereafter, for example, when the direction of the magnetic field MF is changed by 250 ° C.-1H annealing as shown in FIG. 16C, the magnetization 12m of the second magnetization fixed layer 12 in contact with the pinning layer 60 remains rightward. The magnetization 41 cm of the third bias magnetic layer 41 c in contact with the bias pinning layer 42 can be set to face the upper right. As shown in FIG. 16D, this magnetization direction is maintained even after returning to room temperature.

  Thus, the bias to the first magnetization fixed layer 11 and the second magnetic layer 20 (magnetization free layer) is determined by the method of annealing in a magnetic field, the material selection of the pinning layer 60, and the material selection of the bias pinning layer 42. It is possible to arbitrarily set the direction of 20p. Here, as described above, when a tunnel-type strain sensing element using an insulating layer is used for the intermediate layer 30, it is more preferable that the direction of the bias 20p be on the side antiparallel to the magnetization 11m of the first magnetization fixed layer 11. . Specifically, the relative angle between the magnetization 11m of the first magnetization fixed layer 11 and the direction of the bias 20p is preferably 90 ° or more and 270 ° or less, and more preferably 135 ° or more and 225 ° or less. preferable.

FIG. 17A to FIG. 17D are schematic views for explaining another strain sensing element according to the embodiment.
As shown in FIGS. 4D and 4E, in the strain sensing element including the bias layers 40d and 40e that do not use the pinning layer 60, the directions of the first magnetization fixed layer 11 and the bias 20p are arbitrarily set. Is possible. For example, as shown in FIG. 17A, the direction of the bias 20p can be set to 135 ° (or 225 °) with respect to the direction of the magnetization 11m of the first magnetization fixed layer 11. Such a direction of the bias 20p can be set by magnetizing in different directions at a low temperature near room temperature after annealing in a magnetic field as shown in FIGS. 17 (b) and 17 (c).

  In the configuration shown in FIGS. 17A to 17D, the first magnetization fixed layer 11 is fixed by the pinning layer 60. On the other hand, since the first bias magnetic layer 41a is not accompanied by a bias pinning layer, a material such as a permanent magnet having hard magnetic characteristics is used. In the case of such a strain sensing element 100k, no heat treatment is required for setting the magnetization 41am of the first bias magnetic layer 41a. Therefore, the magnetization 11m of the first magnetization fixed layer 11 is fixed by a heat treatment in a magnetic field, and then the first bias magnetic layer 41a made of a hard magnetic material is magnetized by applying a magnetic field after the heat treatment. Here, when a tunnel-type strain sensing element using an insulating layer is used for the intermediate layer 30, for example, the direction of the bias 20 p is more preferably on the side antiparallel to the magnetization 11 m of the first magnetization fixed layer 11. Specifically, the relative angle between the first magnetization fixed layer 11 and the direction of the bias 20p is preferably 90 ° or more and 270 ° or less, and more preferably 135 ° or more and 225 ° or less.

  On the other hand, for the purpose of widening the dynamic range of strain changing resistance, the relative angle between the first magnetization fixed layer 11 and the direction of the bias 20p is 30 ° to 60 °, or 120 ° to 150 °. It is desirable to do.

FIG. 18 is a schematic perspective view illustrating another strain sensing element used in the embodiment.
As illustrated in FIG. 18, in the strain sensing element 100l, an insulating layer is provided. That is, two insulating layers 81 (insulating portions) that are separated from each other are provided between the first electrode E1 and the second electrode E2. Between the first electrode E1 and the second electrode E2, the underlayer 50 / pinning layer 60 / second magnetization fixed layer 12 / magnetic coupling layer 13 / first magnetization fixed layer 11 (first magnetic layer 10) / intermediate layer A laminate of 30 / second magnetic layer 20 / bias layer 40 / cap layer 70 is disposed. This stacked body is disposed between the first electrode E1 and the second electrode E2.

In the case of the strain sensing element 100l, this stacked body includes the underlayer 50, the first magnetic layer 10 (first magnetization free layer), the intermediate layer 30, and the second magnetic layer 20 (second magnetization free layer). And a cap layer 70. That is, the insulating layer 81 is provided to face the side wall of the stacked body.
For the insulating layer 81, for example, aluminum oxide (for example, Al ₂ O ₃ ), silicon oxide (for example, SiO ₂ ), or the like can be used. The insulating layer 81 can suppress leakage current around the stacked body.

FIG. 19 is a schematic perspective view illustrating another strain sensing element used in the embodiment.
As illustrated in FIG. 19, in the strain sensing element 100m, a hard bias layer 83 is further provided. That is, two hard bias layers 83 (hard bias portions) that are separated from each other are provided between the first electrode E1 and the second electrode E2. Between the first electrode E1 and the second electrode E2, the underlayer 50 / pinning layer 60 / second magnetization fixed layer 12 / magnetic coupling layer 13 / first magnetization fixed layer 11 (first magnetic layer 10) / intermediate layer A laminate of 30 / second magnetic layer 20 / bias layer 40 / cap layer 70 is disposed. An insulating layer 81 is disposed between the hard bias layer 83 and this stacked body. In this example, the insulating layer 81 extends between the hard bias layer 83 and the first electrode E1.

  Due to the magnetization of the hard bias layer 83, at least one of the magnetization 10m of the first magnetic layer 10 and the magnetization 20m of the second magnetic layer 20 is set in a desired direction. The hard bias layer 83 can set at least one of the magnetization 10m of the first magnetic layer 10 and the magnetization 20m of the second magnetic layer 20 in a desired direction in a state where no force is applied to the substrate.

For the hard bias layer 83, for example, a hard ferromagnetic material having a relatively high magnetic anisotropy such as CoPt, CoCrPt, or FePt is used. The hard bias layer 83 may have a structure in which a layer of a soft magnetic material such as FeCo or Fe and an antiferromagnetic layer are stacked. In this case, the magnetization follows a predetermined direction by exchange coupling. The thickness of the hard bias layer 83 (for example, the length along the direction from the first electrode E1 to the second electrode E2) is, for example, not less than 5 nm and not more than 50 nm.
The hard bias layer 83 and the insulating layer 81 can be applied to any of the strain sensing elements described later.

FIG. 20 is a schematic plan view illustrating an example of the bias direction of the bias layer and the bias direction of the hard bias.
In the example shown in FIG. 20, the direction of the bias 20 pb of the first bias magnetic layer 41 a is set antiparallel to the first magnetization fixed layer 11. The direction of the magnetic field bias 20ph of the hard bias layer 83 relative to the first magnetization fixed layer 11 is set to 135 ° (or 225 °).

  The initial magnetization 20mf (the direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) is 135 from the competition between the bias 20pb from the first bias magnetic layer 41a and the magnetic field bias 20ph from the hard bias layer 83. Between 180 ° and 180 ° (or between 180 ° and 225 °). Thus, when the hard bias layer 83 is provided in the strain sensing element of the embodiment including the bias layer 40, the initial magnetization 20mf (direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) is the first magnetization fixed layer. 11 is preferably set to 90 ° or more and 270 ° or less, and more preferably set to 135 ° or more and 225 ° or less. Here, when the direction of the strain applied to the strain sensing element of the embodiment is parallel or perpendicular to the direction of the magnetization 11m of the first magnetization fixed layer 11 as indicated by arrows A101 and A102 shown in FIG. In the range of 90 °, which is the dynamic range of magnetization in which the second magnetic layer 20 (magnetization free layer) rotates due to strain, a monotonically increasing or monotonically decreasing electrical resistance change can be obtained. Therefore, it is preferable.

(Second Embodiment)
FIG. 21A and FIG. 21B are schematic views illustrating the strain sensing element according to the second embodiment.
FIG. 21A is a schematic cross-sectional view illustrating a pressure sensor in which a strain sensing element is used. FIG. 21B is a schematic perspective view of the strain sensing element.

  As shown in FIG. 21A, the strain sensing element 300 is used for the pressure sensor 200a. The pressure sensor 200a includes a substrate 210 and a strain sensing element 300. The substrate 210 has a flexible region. The strain sensing element 300 is provided on a part of the substrate 210. The pressure sensor 200a is the same as the pressure sensor 200 described above with reference to FIG.

  As shown in FIG. 21B, the strain sensing element 300 according to the embodiment includes a lower bias layer 110, a lower magnetic layer 10, an intermediate layer 30, an upper magnetic layer 20, an upper bias layer 120, including.

  The upper bias layer 120 is provided separately from the lower bias layer 110 in the stacking direction. The lower magnetic layer 10 is provided between the lower bias layer 110 and the upper bias layer 120. An intermediate layer 30 is provided between the lower magnetic layer 10 and the upper bias layer 120. The upper magnetic layer 20 is provided between the intermediate layer 30 and the upper bias layer 120.

  The lower magnetic layer 10 is, for example, a first magnetization free layer whose magnetization changes according to the bending of the substrate 210. The upper magnetic layer 20 is, for example, a second magnetization free layer whose magnetization changes according to the bending of the substrate 210. As will be described later, when a force is applied to the substrate 210 and the substrate 210 is bent, the magnetization of the lower magnetic layer 10 (first magnetization free layer) and the magnetization of the upper magnetic layer 20 (second magnetization free layer) are relative to each other. Changes can be made to the angle.

Next, the operation of the strain sensing element 300 will be illustrated.
FIG. 22A to FIG. 22C are schematic views illustrating the operation of the strain sensing element according to the second embodiment.
22A to 22C exemplify a case where the first magnetization free layer is used as the lower magnetic layer 10 and the second magnetization free layer is used as the upper magnetic layer 20. In FIG. 22A to FIG. 22C, the lower magnetic layer 10 (first magnetization free layer), the intermediate layer 30, and the upper magnetic layer 20 among the layers of the strain sensing element 300 for ease of viewing. (Second magnetization free layer) is shown.

  The operation in which the strain sensing element 300 functions as a strain sensor is based on the application of the “inverse magnetostriction effect” and the “magnetoresistance effect”. The “inverse magnetostriction effect” is obtained in the ferromagnetic layer used for the magnetization free layer. The “magnetoresistance effect” is manifested in a laminated film of the first magnetization free layer, the intermediate layer, and the second magnetization free layer.

  The “inverse magnetostriction effect” is as described above with reference to FIGS. 2 (a) to 2 (c). That is, due to the strain, the magnetization direction of the first magnetization free layer and the magnetization direction of the second magnetization free layer change, the magnetization direction of the first magnetization free layer, the magnetization direction of the second magnetization free layer, The relative angle of changes. That is, the MR effect is manifested by the inverse magnetostrictive effect.

  When the ferromagnetic material used for the first magnetization free layer and the second magnetization free layer has a positive magnetostriction constant, the angle between the direction of magnetization and the direction of tensile strain becomes small, and the direction of magnetization and the direction of compression strain The direction of magnetization changes so that the angle between and increases. When the ferromagnetic material used for the first magnetization free layer and the second magnetization free layer has a negative magnetostriction constant, the angle between the direction of magnetization and the direction of tensile strain increases, and the direction of magnetization and the direction of compression strain The direction of magnetization changes so that the angle between and becomes smaller.

  When the combination of the material of the laminated film of the first magnetization free layer, the intermediate layer, and the second magnetization free layer has a positive magnetoresistance effect, the relative angle between the first magnetization free layer and the second magnetization free layer is small. In some cases, the electrical resistance decreases. When the combination of the materials of the laminated film of the first magnetization free layer, the intermediate layer, and the second magnetization free layer has a negative magnetoresistance effect, the relative angle between the first magnetization free layer and the second magnetization free layer is small. In some cases, the electrical resistance increases.

  Hereinafter, the ferromagnetic materials used for the first magnetization free layer and the second magnetization free layer each have a positive magnetostriction constant, and the first magnetization free layer, the intermediate layer, and the second magnetization free layer are stacked. An example of the change in magnetization will be described with respect to an example where the film has a positive magnetoresistance effect.

  As shown in FIG. 22B, the relative relationship between the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) included in the magnetization free layer in the initial state without distortion. The angle can be arbitrarily set by a bias direction from the lower bias layer 110 and the upper bias layer 120, or a bias magnetic field from a hard bias.

  In the example shown in FIGS. 22A to 22C, the bias direction applied from the lower bias layer 110 to the lower magnetic layer 10 (first magnetization free layer), and the upper bias layer 120 to the upper magnetic layer 20 (first magnetic layer 20). The bias direction applied to the two magnetization free layers) is antiparallel, and a hard bias is applied in a direction perpendicular to the bias directions from the lower bias layer 110 and the upper bias layer 120 in the plane, so that the lower magnetic layer 10 in the initial state A state in which the relative angle between the (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) in the initial state is greater than 0 ° and less than 180 ° is illustrated. Details of the method of setting the initial magnetization direction will be described later.

  In FIG. 22A, when a tensile strain corresponding to the tensile stress ts in the direction of the arrow occurs, the magnetization 10m of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer). Is changed from the initial magnetization direction without strain so that the angle with the direction in which the tensile stress ts is applied becomes small. In the example shown in FIG. 22A, when a tensile stress ts is applied, the magnetization 10 m of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (the first magnetization free layer) are compared with the initial magnetization direction without strain. The relative angle of the second magnetization free layer) to the magnetization 20m is reduced, and the electrical resistance of the strain sensing element 300 is reduced.

  On the other hand, in FIG. 22C, when a compressive strain corresponding to the compressive stress cs occurs in the direction of the arrow, the magnetization 10m of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization) The magnetization 20m of the free layer changes from the initial magnetization direction without strain so that the angle with the direction in which the compressive stress cs is applied becomes large. In the example shown in FIG. 22C, when compressive stress cs is applied, the magnetization 10m of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 ( The relative angle of the second magnetization free layer) to the magnetization 20m increases, and the electrical resistance of the strain sensing element 300 increases.

  As shown in FIG. 21B, the lower bias layer 110 provided in contact with the lower magnetic layer 10 (first magnetization free layer) and the upper bias provided in contact with the upper magnetic layer 20 (second magnetization free layer). In the strain sensing element 300 including the layer 120, magnetic coupling from the lower bias layer 110 to the lower magnetic layer 10 (first magnetization free layer) and from the upper bias layer 120 to the upper magnetic layer 20 (second magnetization free layer). By magnetic coupling, the anisotropic magnetic field of the lower magnetic layer 10 (first magnetization free layer) and the anisotropic magnetic field of the upper magnetic layer 20 (second magnetization free layer) can be increased to appropriate values. By increasing the anisotropic magnetic field of the lower magnetic layer 10 (first magnetization free layer) and the anisotropic magnetic field of the upper magnetic layer 20 (second magnetization free layer), the lower magnetic layer 10 (first magnetization free layer) The reversibility of the change of the magnetization 10m and the magnetization 20m of the upper magnetic layer 20 (second magnetization free layer) can be increased, and a high gauge factor can be obtained. The principle of improving the reversibility of changes in the magnetizations 10m and 20m with respect to the strain of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) is the same as described in the first embodiment. Is the same.

  When the dimension of the strain sensing element 300 is reduced, the lower magnetic layer 10 is affected by the magnetic poles at the end portions of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer). A demagnetizing field is generated inside the (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer), so that the magnetization 10 m of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization layer) The magnetization 20m of the magnetization free layer may be disturbed. When the magnetization 10m of the lower magnetic layer 10 (first magnetization free layer) and the magnetization 20m of the upper magnetic layer 20 (second magnetization free layer) are disturbed, the lower magnetic layer 10 (first magnetization free layer) due to the strain of the strain sensing element 300 is disturbed. Change in the relative angle between the magnetization 10 m of the layer) and the magnetization 20 m of the upper magnetic layer 20 (second magnetization free layer) may be reduced. Reducing the demagnetizing field of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) is to provide a highly sensitive strain sensor in the strain sensing element 300 having a small size. It is one of the important matters. Increasing the anisotropic magnetic field of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) is also effective in reducing the influence of such a demagnetizing field. Accordingly, high strain detection sensitivity can be realized even in the strain detection element 300 having a relatively small size. As a result, the strain sensing element 300 having both high resolution and high sensitivity can be provided.

  As shown in FIG. 21B, the lower magnetic layer 10 and the upper magnetic layer 20 are provided with an independent lower bias layer 110 and upper bias layer 120, respectively. There is an advantage that the initial magnetization direction with 20 can be arbitrarily set.

An example of the strain sensing element 300 according to the second embodiment will be described.
FIG. 23 is a schematic perspective view illustrating a strain sensing element used in the second embodiment.
As shown in FIG. 23, the strain sensing element 300a used in the embodiment includes the first electrode E1, the underlayer 50, the lower bias layer 110, the lower magnetic layer 10, the intermediate layer 30, and the upper magnetic layer. 20, an upper bias layer 120, a cap layer 70, and a second electrode E2. An underlayer 50 is provided between the first electrode E1 and the second electrode E2. A lower bias layer 110 is provided between the base layer 50 and the second electrode E2. The lower magnetic layer 10 is provided between the lower bias layer 110 and the second electrode E2. An intermediate layer 30 is provided between the lower magnetic layer 10 and the second electrode E2. The upper magnetic layer 20 is provided between the intermediate layer 30 and the second electrode E2. An upper bias layer 120 is provided between the upper magnetic layer 20 and the second electrode E2. A cap layer 70 is provided between the upper bias layer 120 and the second electrode E2.

For example, Ta / Ru is used for the underlayer 50. The thickness of this Ta layer (the length in the Z-axis direction) is, for example, 3 nm. The thickness of this Ru layer is 2 nm, for example.
For example, IrMn (7 nm) / Fe ₅₀ Co ₅₀ (3 nm) / Cu (2.5 nm) is used for the lower bias layer 110.

For the lower magnetic layer 10 (first magnetization free layer), for example, Co ₄₀ Fe ₄₀ B ₂₀ (4 nm) is used.
For example, MgO (2 nm) is used for the intermediate layer 30.
For example, Co ₄₀ Fe ₄₀ B ₂₀ (4 nm) is used for the upper magnetic layer 20 (second magnetization free layer). For the upper bias layer 120, for example, Cu (2.5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm) is used.
For example, Ta (2 nm) / Ru (5 nm) is used for the cap layer 70.

  As the material of each layer in the second embodiment, the same material as the layer having the same name in the first embodiment can be used. That is, the same material as the magnetization free layer of the first embodiment can be used for the lower magnetic layer (first magnetization free layer) and the upper magnetic layer (second magnetization free layer) of the second embodiment. The same material as the bias layer of the first embodiment can be used for the lower bias layer and the upper bias layer of the second embodiment.

(Details of Bias Layer of Second Embodiment)
FIG. 24A and FIG. 24B are schematic perspective views illustrating the bias layer of the second embodiment.
FIG. 24A and FIG. 24B show the lower bias provided for the lower magnetic layer 10 (first magnetization free layer) / intermediate layer 30 / upper magnetic layer 20 (second magnetization free layer) stack. A lower bias layer 110 in which the lower magnetic layer 10 is provided between the intermediate layer 30 and the lower bias layer 110, and an upper portion between the intermediate layer 30 and the upper bias layer 120. The example of the variation of the structure of the upper bias layer 120 in which the magnetic layer 20 is provided is represented.

The lower bias layer 110a shown in FIG. 24A includes a lower bias pinning layer 42a, a lower first bias magnetic layer 111a (first bias magnetic layer), and a lower isolation layer 43a. A lower first bias magnetic layer 111a is provided between the lower bias pinning layer 42a and the lower isolation layer 43a.
The upper bias layer 120a shown in FIG. 24A includes an upper isolation layer 43b, an upper first bias magnetic layer 121a (second bias magnetic layer), and an upper first magnetic coupling layer 124a (first magnetic coupling layer). And an upper second bias magnetic layer 121b (third bias magnetic layer) and an upper bias pinning layer 42b. An upper first bias magnetic layer 121a is provided between the upper isolation layer 43b and the upper bias pinning layer 42b. An upper first magnetic coupling layer 124a is provided between the upper first bias magnetic layer 121a and the upper bias pinning layer 42b. An upper second bias magnetic layer 121b is provided between the upper first magnetic coupling layer 124a and the upper bias pinning layer 42b.

  The lower first bias magnetic layer 111a is formed of, for example, a magnetic material, and the direction of the magnetization 111am is fixed in one direction by the lower bias pinning layer 42a. A bias 10p is applied to the lower magnetic layer 10 (first magnetization free layer) from the lower bias layer 110a whose magnetization is fixed in one direction by magnetic coupling such as exchange coupling to the lower magnetic layer 10 (first magnetization free layer). Added.

  The upper second bias magnetic layer 121b is formed of, for example, a magnetic material, and the direction of the magnetization 121bm is fixed in one direction by the upper bias pinning layer 42b. The upper second bias magnetic layer 121b and the upper first bias magnetic layer 121a, whose magnetization is fixed in one direction, are magnetically coupled in antiparallel via the upper magnetic coupling layer 124a, and the upper magnetic field is separated from the upper first bias magnetic layer 121a. A bias 20p is applied to the upper magnetic layer 10 (second magnetization free layer) by magnetic coupling such as exchange coupling to the layer 20 (second magnetization free layer).

  The lower separation layer 43a is made of, for example, a nonmagnetic material, and physically separates the lower first bias magnetic layer 111a and the lower magnetic layer 10 (first magnetization free layer), thereby lowering the lower first bias magnetic layer. Arranged to adjust the strength of magnetic coupling between 111a and the lower magnetic layer 10 (first magnetization free layer). Here, depending on the material of the lower first bias magnetic layer 111a, the lower isolation layer 43a is not necessarily provided.

For the lower separation layer 43a, for example, Cu (2.5 nm) can be used. For example, Cu (2.5 nm) can be used for the upper separation layer 43b. For example, 3 nm Fe ₅₀ Co ₅₀ can be used for the lower first bias magnetic layer 111a. For the upper first bias magnetic layer 121a, for example, 2 nm of Fe ₅₀ Co ₅₀ can be used. For example, 0.9 nm of Ru can be used for the upper first magnetic coupling layer 124a. For the upper second bias magnetic layer 121b, for example, 2 nm of Fe ₅₀ Co ₅₀ can be used. For example, IrMn of 7 nm can be used for the lower bias pinning layer 42a. For the upper bias pinning layer 42b, for example, IrMn of 7 nm can be used.

For example, at least one selected from the group consisting of Co, Fe, and Ni is used for each of the lower first bias magnetic layer 111a, the upper first bias magnetic layer 121a, and the upper second bias magnetic layer 121b. As each of the lower first bias magnetic layer 111a, the upper first bias magnetic layer 121a, and the upper second bias magnetic layer 121b, an alloy containing at least one material selected from these materials may be used. For example, a Co _x Fe _100-x alloy, a Ni _x Fe _100-x alloy, or a material obtained by adding a nonmagnetic element to these is used. In the Co _x Fe _100-x alloy, x is 0 at. % Or more and 100 at. % Or less. In the Ni _x Fe _100-x alloy, x is 0 at. % Or more and 100 at. % Or less.

As each of the lower first bias magnetic layer 111a, the upper first bias magnetic layer 121a, and the upper second bias magnetic layer 121b, a (Co _x Fe _100-x ) _{100- y By} alloy can also be used. In the (Co _x Fe _100-x ) _{100- y By} alloy, x is 0 at. % Or more and 100 at. % And y is 0 at. % Or more and 30 at. % Or less. Lower first bias magnetic layer 111a, as each of the upper first bias magnetic layer 121a and the upper second bias magnetic layer _121b, by using a _{(Co x Fe 100-x)} 100-y B y of the amorphous alloy, the detection element Even when the size is small, the variation among the strain sensing elements 300 can be suppressed.

The thickness of each of the lower first bias magnetic layer 111a, the upper first bias magnetic layer 121a, and the upper second bias magnetic layer 121b is preferably, for example, 1.5 nm or more and 5 nm or less. Thereby, for example, the strength of the unidirectional anisotropic magnetic field by the lower bias pinning layer 42a and the upper bias pinning layer 42b can be sufficiently obtained. As each of the lower first bias magnetic layer 111a, the upper first bias magnetic layer 121a, and the upper second bias magnetic layer 121b, for example, Fe ₅₀ Co _{50 of} 3 nm can be used.

  For example, a nonmagnetic material can be used for each of the lower separation layer 43a and the upper separation layer 43b. As each of the lower separation layer 43a and the upper separation layer 43b, Cu, Ru, Rh, Ir, V, Cr, Nb, Mo, Ta, W, Rr, Au, Ag, Pt, Pd, Ti, Zr, Hf, and A layer containing at least one element selected from the group of Hf can be used. For example, 5 nm of Cu can be used as each of the lower separation layer 43a and the upper separation layer 43b.

  The lower bias pinning layer 42a imparts unidirectional anisotropy to the lower first bias magnetic layer 111a formed in contact with the lower bias pinning layer 42a to fix the magnetization 111am. For the lower bias pinning layer 42a, for example, an antiferromagnetic layer is used. For the lower bias pinning layer 42a, for example, at least one selected from the group consisting of IrMn, PtMn, PdPtMn, and RuRhMn is used. In order to impart sufficient strength of unidirectional anisotropy, the thickness of the lower bias pinning layer 42a is appropriately set.

  The upper bias pinning layer 42b imparts unidirectional anisotropy to the upper second bias magnetic layer 121b formed in contact with the upper bias pinning layer 42b to fix the magnetization 121bm. For example, an antiferromagnetic layer is used for the upper bias pinning layer 42b. For the upper bias pinning layer 42b, for example, at least one selected from the group consisting of IrMn, PtMn, PdPtMn, and RuRhMn is used. In order to impart sufficient strength of unidirectional anisotropy, the thickness of the upper bias pinning layer 42b is appropriately set.

When PtMn or PdPtMn is used as each of the lower bias pinning layer 42a and the upper bias pinning layer 42b, the thickness of each of the lower bias pinning layer 42a and the upper bias pinning layer 42b is preferably 8 nm or more and 20 nm or less. The thicknesses of the lower bias pinning layer 42a and the upper bias pinning layer 42b are more preferably 10 nm or more and 15 nm or less. When IrMn is used as each of the lower bias pinning layer 42a and the upper bias pinning layer 42b, the pinning layer is thinner than the case where PtMn is used as each of the lower bias pinning layer 42a and the upper bias pinning layer 42b. Sex can be imparted. In this case, the thickness of each of the lower bias pinning layer 42a and the upper bias pinning layer 42b is preferably 4 nm or more and 18 nm or less. The thicknesses of the lower bias pinning layer 42a and the upper bias pinning layer 42b are more preferably 5 nm or more and 15 nm or less. For example, an Ir ₂₂ Mn ₇₈ layer having a thickness of 7 nm is used for each of the lower bias pinning layer 42a and the upper bias pinning layer 42b.

A hard magnetic layer may be used as each of the lower bias pinning layer 42a and the upper bias pinning layer 42b. As a hard magnetic layer, for _{example, CoPt, (Co x Pt 100} -x) 100-y Cr y , or the like may be used FePt. In CoPt, the Co ratio is 50 at. % Or more and 85 at. % Or less. In _{(Co x Pt 100-x)} 100-y Cr y, x is 50at. % Or more and 85 at. % And y is 0 at. % Or more and 40 at. % Or less. In FePt, the Pt ratio is 40 at. % Or more and 60 at. % Or less.

  The upper first magnetic coupling layer 124a generates antiferromagnetic coupling between the upper first bias magnetic layer 121a and the upper second bias magnetic layer 121b. The upper first magnetic coupling layer 124a forms a synthetic pin structure. For example, Ru is used as the upper first magnetic coupling layer 124a. The thickness of the upper first magnetic coupling layer 124a is preferably 0.8 nm or more and 1 nm or less. Any material other than Ru may be used for the upper first magnetic coupling layer 124a as long as it is a material that causes sufficient antiferromagnetic coupling between the upper first bias magnetic layer 121a and the upper second bias magnetic layer 121b. . The thickness of the upper first magnetic coupling layer 124a can be set to a thickness of 0.8 nm or more and 1 nm or less corresponding to a second peak (2nd peak) of RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling. Furthermore, the thickness of the upper first magnetic coupling layer 124a may be set to a thickness of 0.3 nm or more and 0.6 nm or less corresponding to the first peak (1st peak) of the RKKY coupling. As the upper first magnetic coupling layer 124a, for example, Ru having a thickness of 0.9 nm is used. Thereby, highly reliable coupling can be obtained more stably.

  The thicknesses of the upper first bias magnetic layer 121a and the upper second bias magnetic layer 121b are preferably, for example, 1.5 nm or more and 5 nm or less, respectively. Thereby, for example, the strength of the unidirectional anisotropic magnetic field by the upper bias pinning layer 42b can be further increased. The magnetic film thickness (the product of the saturation magnetization Bs and the thickness t (Bs · t)) of the upper first bias magnetic layer 121a is preferably substantially equal to the magnetic film thickness of the upper second bias magnetic layer 121b.

In the case where the same magnetic material is used for the upper first bias magnetic layer 121a and the upper second bias magnetic layer 121b, it is preferable that their film thicknesses are made uniform. When different magnetic materials are used for the upper first bias magnetic layer 121a and the upper second bias magnetic layer 121b, for example, Co ₄₀ Fe ₄₀ B ₂₀ is used for the upper first bias magnetic layer 121a and the upper second bias magnetic layer 121b is used. When Co ₇₅ Fe ₂₅ is used, the saturation magnetization of Co ₄₀ Fe ₄₀ B _{20 in} the thin film is about 1.9 T (Tesla), and the saturation magnetization of Co ₇₅ Fe ₂₅ is about 2.1 T. For example, when a Co ₄₀ Fe ₄₀ B ₂₀ layer having a thickness of 3 nm is used as the upper first bias magnetic layer 121a, the magnetic film thickness of the upper first bias magnetic layer 121a is 1.9 T × 3 nm, It becomes 5.7 Tnm. The thickness of the upper second bias magnetic layer 121b that can obtain a magnetic film thickness equal to the above is 5.7 Tnm / 2.1T, which is 2.7 nm. In this case, it is preferable to use Co ₇₅ Fe ₂₅ having a thickness of about 2.7 nm for the upper second bias magnetic layer 121b.

FIG. 24B is a schematic perspective view showing another bias layer of the second embodiment.
The lower bias layer 110b shown in FIG. 24B includes a lower bias pinning layer 42a, a lower third bias magnetic layer 111c, a lower second magnetic coupling layer 114b (second magnetic coupling layer), and a lower second bias. It includes a magnetic layer 111b (fourth bias magnetic layer), a lower first magnetic coupling layer 114a, a lower first bias magnetic layer 111a, and a lower isolation layer 43a. A lower third bias magnetic layer 111c is provided between the lower bias pinning layer 42a and the lower isolation layer 43a. A lower second magnetic coupling layer 114b is provided between the lower third bias magnetic layer 111c and the lower isolation layer 43a. A lower second bias magnetic layer 111b is provided between the lower second magnetic coupling layer 114b and the lower isolation layer 43a. A lower first magnetic coupling layer 1114a is provided between the lower second bias magnetic layer 111b and the lower isolation layer 43a. A lower first bias magnetic layer 111a is provided between the lower first magnetic coupling layer 114a and the lower isolation layer 43a.

  The upper bias layer 120b shown in FIG. 24B includes an upper separation layer 43b, an upper first bias magnetic layer 121a, an upper first magnetic coupling layer 124a, an upper second bias magnetic layer 121b, and an upper bias pinning. Layer 42b. An upper first bias magnetic layer 121a is provided between the upper isolation layer 43b and the upper bias pinning layer 42b. An upper first magnetic coupling layer 124a is provided between the upper first bias magnetic layer 121a and the upper bias pinning layer 42b. An upper second bias magnetic layer 121b is provided between the upper first magnetic coupling layer 124a and the upper bias pinning layer 42b.

  In FIG. 24A, the bias magnetic layer in the lower bias layer 110a is a single layer, whereas in FIG. 24B, in the lower bias layer 110b, the lower first magnetic coupling layer 114a and the lower second magnetic layer The difference is that three bias magnetic layers are provided via the magnetic coupling layer 114b. The plurality of bias magnetic layers can be set so that the magnetization directions of adjacent bias magnetic layers are opposite to each other via the magnetic coupling layer. In this way, by using a plurality of bias magnetic layers and making their magnetization directions anti-parallel, the leakage magnetic field from the bias magnetic layer to the outside is suppressed, and a magnetic other than bias application by exchange coupling to the magnetization free layer is performed. Interference can be suppressed.

  In FIG. 24B, since a plurality of bias magnetic layers are used for both the lower bias layer 110b and the upper bias layer 120b, the leakage magnetic field from the bias magnetic layer to the outside is reduced. The bias layer 110b and the upper bias layer 120b) can be suppressed.

  As shown in the lower bias layer 110b in FIG. 24B, when three bias magnetic layers are used, the magnetization 111am of the lower first bias magnetic layer 111a and the magnetization 111cm of the lower third bias magnetic layer 111c are in the same direction. Only the magnetization 111bm of the lower second bias magnetic layer 111b is reversed. In the case of using a plurality of bias magnetic layers in such an odd number, from the viewpoint of reducing the leakage magnetic field, the magnetic film of the bias magnetic layer in which the sum of the magnetic film thicknesses of the bias magnetic layers facing in the same direction is directed in the opposite direction It is preferable to make it equal to the sum of the thicknesses. For example, when using three bias magnetic layers as shown in FIG. 24B, the sum of the magnetic film thickness of the lower first bias magnetic layer 111a and the magnetic film thickness of the lower third bias magnetic layer 111c is It is preferably set to be equal to the magnetic film thickness of the lower second bias magnetic layer 111b.

The material of each layer included in FIG. 24B can be the same as that shown in FIG.
For the lower bias pinning layer 42a, for example, IrMn of 7 nm can be used. For the lower third bias magnetic layer 111c, for example, 2 nm of Fe ₅₀ Co ₅₀ can be used. For example, Ru of 0.9 nm can be used for the lower second magnetic coupling layer 114b. For the lower first bias magnetic layer 111a, for example, Fe ₅₀ Co _{50 of} 4 nm can be used. For example, 0.9 nm of Ru can be used for the lower first magnetic coupling layer 114a. For the lower first bias magnetic layer 111a, for example, 2 nm of Fe ₅₀ Co ₅₀ can be used. For the lower separation layer 43a, for example, 2.5 nm of Cu can be used.

For the upper isolation layer 43b, for example, 2.5 nm of Cu can be used. As the upper first bias magnetic layer 121a, 2 nm of Fe ₅₀ Co ₅₀ can be used. For example, 0.9 nm of Ru can be used for the upper first magnetic coupling layer 124a. For the upper second bias magnetic layer 121b, 2 nm of Fe ₅₀ Co ₅₀ can be used. For the upper bias pinning layer 42b, for example, IrMn of 7 nm can be used.

FIG. 24A illustrates a case where a single bias magnetic layer is used for the lower bias layer 110a and two bias magnetic layers are used for the upper bias layer 120a. FIG. 24B illustrates a case where three bias magnetic layers are used for the lower bias layer 110b and two bias magnetic layers are used for the upper bias layer 120b. The number of bias magnetic layers included in the lower bias layers 110a and 110b and the upper bias layers 120a and 120b can be appropriately adjusted.
The bias layer may include four or more bias magnetic layers.

  When the number of bias magnetic layers included in each of the lower bias layer 110 and the upper bias layer 120 is odd-even and even-odd, the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 are used. The bias direction applied to each of the (second magnetization free layer) is antiparallel. When the number of bias magnetic layers included in each of the lower bias layer 110 and the upper bias layer 120 is odd-odd and even-even, the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 are used. The bias direction applied to each of the (second magnetization free layer) is parallel. In either case, it can function as a strain sensor. When the bias directions applied to the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) are antiparallel to each other, the antiparallel magnetization alignment is more likely to be trapped due to strain. It is more preferable because a close operation can be obtained and a high gauge factor can be realized.

  Here, when a tunnel type strain sensing element using an insulating layer is used for the intermediate layer 30, the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetic layer 20) are used from the viewpoint of obtaining a large change in electrical resistance. The bias directions applied to the magnetization free layer are more preferably antiparallel to each other. This is because, in a tunnel type strain sensing element, the relative angle between the pinned layer and the free layer changes between 90 ° and 180 °, rather than between 0 ° and 90 °. This is because the change in electric resistance can be greater in this case, and it is easier to obtain a higher gauge factor when driven as a strain sensor between 90 ° and 180 °. The closer the relative angle between the pinned layer and the free layer is to 180 °, the greater the electrical resistance change with respect to the relative angle change per unit. Therefore, the number of bias magnetic layers included in each of the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) is preferably odd-even and even-odd.

As a fifth example according to the embodiment, a strain sensing element 300 having the following structure is manufactured.
(Fifth embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Lower bias layer 110: Ir ₂₂ Mn ₇₈ (7 nm) / Fe ₅₀ Co ₅₀ (3 nm) / Cu (2.5 nm)
Lower magnetic layer 10 (first magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Intermediate layer 30: MgO (2 nm)
Upper magnetic layer 20 (second magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Upper bias layer 120: Cu (2.5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm)
Cap layer 70: Ta (2 nm) / Ru (5 nm)
The structure of the strain sensing element 300 of the fifth embodiment is the same as that of the strain sensing element 300a shown in FIG. The structure of the lower bias layer 110 is the same as that of the lower bias layer 110a shown in FIG. The lower bias layer 110 includes a lower bias pinning layer 42a / a lower first bias magnetic layer 111a / a lower isolation layer 43a. The structure of the upper bias layer 120 is the same as that of the upper bias layer 120a shown in FIG. The upper bias layer 120 is an upper separation layer 43b / upper first bias magnetic layer 121a / upper first magnetic coupling layer 124a / upper second bias magnetic layer 121b / upper bias pinning layer 42b.

As a second comparative example, a strain sensing element having the following structure is manufactured.
(Comparative Example 2)
Underlayer 50: Ta (1 nm) / Cu (15 nm)
Lower magnetic layer 10 (first magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Intermediate layer 30: MgO (2 nm)
Upper magnetic layer 20 (second magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Cap layer 70: Cu (15 nm) / Ta (2 nm) / Ru (5 nm)
In the second comparative example, no bias layer is provided.
The laminated body of the fifth example is annealed while applying a magnetic field of 6500 Oe at 320 ° C. and 1 H after molding to fix the magnetization of the lower bias layer 110 and the upper bias layer 120.

FIG. 25A to FIG. 25D are graphs showing examples of results of magnetic characteristics before element processing of the laminated body of the fifth example.
FIG. 25A shows an example of a BH loop in which the case where a magnetic field is applied in the direction in which the heat treatment in a magnetic field is performed is evaluated as a positive magnetic field in the fifth example. FIG. 25B shows an example of a BH loop evaluated by applying a magnetic field in the direction perpendicular to the heat treatment direction in the magnetic field and in the plane in the fifth example. FIG. 25C illustrates an example of a BH loop in which a case where a magnetic field is applied in a direction in which heat treatment in a magnetic field is performed is evaluated as a positive magnetic field in the second comparative example. FIG. 25D shows an example of a BH loop evaluated in the second comparative example by applying a magnetic field in the direction perpendicular to the heat treatment direction in the magnetic field and in the plane.

  In the BH loop shown in FIG. 25A, one easy-axis loop shape with good squareness is obtained in the negative magnetic field and one in the positive magnetic field, and anti-parallel in the zero magnetic field. It turns out that it is. In the BH loop shown in FIG. 25B, a loop shape with a typical hard axis is obtained. From this result, it is understood that in-plane induced magnetic anisotropy with the easy axis in the direction of heat treatment in the magnetic field is obtained in each magnetization free layer of the fifth embodiment.

In the BH loop shown in FIG. 25C, a loop shape of an easy magnetization axis with good squareness is obtained. In the BH loop shown in FIG. 25B, a loop shape with a typical hard axis is obtained. From this result, it can be seen that in-plane induced magnetic anisotropy is obtained in the magnetization free layer with the direction of heat treatment in a magnetic field as the easy axis. As can be seen from FIG. 25 (c), in the second comparative example in which no bias layer is provided, the lower magnetic layer 10 and the upper magnetic layer 20 are simultaneously reversed and are parallel with zero magnetic field. An anisotropy magnetic field H _k indicating the strength of in-plane induced magnetic anisotropy is estimated to be 16.9 Oe as an average value of the lower magnetic layer 10 and the upper magnetic layer 20.

From the BH loop of FIG. 25A, the lower magnetic layer 10 (first magnetization free layer) is biased to the negative magnetic field side. H _shift is estimated to be -8.8 Oe. Coercivity _{H c} is estimated to 3.4Oe. From the BH loop of FIG. 25A, the upper magnetic layer 20 (second magnetization free layer) is biased to the positive magnetic field side. H _shift is estimated at 10.5 Oe. Coercivity _{H c} is estimated to 3.1Oe.

The coercive force is a characteristic index indicating the ease of magnetization rotation. It can be said that the coercive force of about 3 Oe is a value at which magnetization rotation due to the inverse magnetostriction effect easily occurs. As a result of evaluating the magnetostriction constant of the fifth example, the average value of the magnetostriction constants of the two magnetization free layers is calculated to be 20 ppm. This value is high enough to cause magnetization rotation for high strain. The anisotropic magnetic field H _k calculated from the BH loop of FIG. 25B related to the strength of the induced magnetic anisotropy is estimated to be 18.7 Oe, and a bias layer is provided for the second comparative example. This confirms that the anisotropic magnetic field is improved.

From the results of FIGS. 25A to 25D, the configuration of the magnetization free layer of the fifth example is the same as the configuration of the magnetization free layer of the second comparative example. The coercive force of the fifth example is equivalent to the coercive force of the second comparative example. The magnetostriction constant of the fifth example is equivalent to the magnetostriction constant of the second comparative example. In the fifth example, it can be seen that the anisotropic magnetic field is improved as compared with the second comparative example 2 by providing the bias layer. In the fifth embodiment, a bias is applied from the lower bias layer 110 to the lower magnetic layer 10. A bias is applied from the upper bias layer 120 to the upper magnetic layer 20. The direction of the bias applied from the lower bias layer 110 to the lower magnetic layer 10 is antiparallel to the direction of the bias applied from the upper bias layer 120 to the upper magnetic layer 20. Thereby, it can be seen that the magnetization 10m of the lower magnetic layer 10 (first magnetization free layer) is antiparallel to the magnetization 20m of the upper magnetic layer 20 (second magnetization free layer) at zero magnetic field.
The laminated body of the fifth embodiment is processed into a vertical conduction element by photolithography and milling. The element size of the vertical energization element is 20 μm × 20 μm.

FIG. 26A to FIG. 26D are graphs showing examples of results of strain sensor characteristics of the strain sensing element of the fifth example.
The evaluation of the strain sensor characteristics shown in FIGS. 26A to 26D is performed by the substrate bending method. Strain is applied to a wafer obtained by cutting a wafer of the strain sensing element 300 to be prototyped into a strip shape by a four-point bending method using a knife edge. A load cell is incorporated in a knife edge that bends the strip wafer, and the strain applied to the strain sensing element 300 on the wafer surface is calculated by the load measured by the load cell. For the calculation of the strain, a general theoretical formula of a two-sided support beam represented by the formula (1) described above with reference to FIGS. 10 (a) to 10 (e) is used. The direction of strain application is as described above with reference to FIGS. 10 (a) to 10 (e).

  In the example shown in FIG. 26A, with respect to the strain sensing element 300 of the fifth embodiment having an element size of 20 μm × 20 μm, the strain applied to the strain sensing element 300 is −0.8 (% 0) or more and 0.8. Between (% 0) and below, it is set as a fixed value in increments of 0.2 (% 0). FIG. 26A shows an example of the result of measuring the magnetic field dependence of electrical resistance at each strain. The direction of the external magnetic field at the time of measurement is added to the direction perpendicular to the magnetization direction of each bias layer in the plane. FIG. 26A shows that the RH loop shape changes depending on the applied strain value. This indicates that the in-plane magnetic anisotropy of the magnetization free layer is changed by the inverse magnetostriction effect.

  26 (b) to 26 (d) show a strain sensing element 300 of the fifth embodiment with an external magnetic field fixed and a strain of −0.8 (% 0) or more and 0.8 (% 0) or less. The change of the electrical resistance when sweeping continuously between is shown. The distortion is swept from −0.8 (% 0) to 0.8 (% 0), and then from 0.8 (% 0) to −0.8 (% 0). These results show the strain sensor characteristics. In FIG. 26B, the evaluation is performed by applying an external magnetic field of 5 Oe. In FIG. 26C, evaluation is performed by applying an external magnetic field of 2 Oe. In FIG. 26D, evaluation is performed by applying an external magnetic field of 0 Oe.

  In the strain sensing element 300 of the embodiment, a high gauge factor can be obtained by applying an appropriate bias magnetic field. The external magnetic field can also be applied by providing a hard bias on the side wall of the strain sensing element. In the strain sensing element 300 of the fifth embodiment, an external magnetic field is simply applied by a coil for evaluation. 26 (b) to 26 (d), the gauge factor of the fifth embodiment is estimated from the change in electrical resistance with respect to strain.

  The gauge factor is expressed by Equation (2) described above with reference to FIGS. 10 (a) to 10 (e). From FIG. 26B, in the fifth example, the gauge factor when the external magnetic field is 5 Oe is 1713. From FIG. 26C, in the fifth embodiment, the gauge factor when the external magnetic field is 2 Oe is 2587. From FIG. 26D, in the fifth example, the gauge factor when the external magnetic field is 0 Oe is 3570. From this result, in the fifth example, when the bias magnetic field is 0 Oe, the maximum gauge factor (3570) is obtained.

  From the results shown in FIGS. 26A to 26D, in the fifth example in which the bias layer is provided, a high gauge factor is confirmed with zero external magnetic field. By providing a bias layer, an appropriate antiparallel bias is applied to the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) with zero magnetic field, and the strain sensor. It is considered that the reversibility of characteristics can be improved. The improvement in reversibility by providing the bias layer is considered to be based on the same principle as that described with reference to FIGS. This is probably because the improvement of the anisotropy magnetic field can provide reversible strain sensor characteristics without an extra bias magnetic field.

As a sixth example according to the embodiment, a strain sensing element 300 having the following structure is manufactured.
(Sixth embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Lower bias layer 110: Ir ₂₂ Mn ₇₈ (7 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (4 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Cu (2.5nm)
Lower magnetic layer 10 (first magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Intermediate layer 30: MgO (2 nm)
Upper magnetic layer 20 (second magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (4 nm)
Upper bias layer 120: Cu (2.5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm)
Cap layer 70: Ta (2 nm) / Ru (5 nm)
The structure of the strain sensing element 300 of the sixth embodiment is the same as that of the strain sensing element 300a shown in FIG. The structure of the lower bias layer 110 is the same as that of the lower bias layer 110b shown in FIG. The lower bias layer 110 includes a lower bias pinning layer 42a / a lower third bias magnetic layer 111c / a lower second magnetic coupling layer 114b / a lower second bias magnetic layer 111b / a lower first magnetic coupling layer 114a / a lower first bias magnetic layer. 111a / lower separation layer 43a. The structure of the upper bias layer 120 is the same as that of the upper bias layer 120b shown in FIG. The upper bias layer 120 is an upper separation layer 43b / upper first bias magnetic layer 121a / upper first magnetic coupling layer 124a / upper second bias magnetic layer 121b / upper bias pinning layer 42b. The difference from the fifth embodiment is that the lower bias layer 110 of the fifth embodiment includes a single bias magnetic layer, whereas the lower bias layer 110 of the sixth embodiment has three layers. The bias magnetic layer is included.

FIGS. 27A to 27D are graphs showing examples of the results of the strain sensor characteristics of the strain sensing element of the sixth embodiment.
Similar to the fifth embodiment, the strain sensor characteristics are evaluated.
In the example shown in FIG. 27A, with respect to the strain sensing element 300 of the sixth embodiment having an element size of 20 μm × 20 μm, the strain applied to the strain sensing element 300 is −0.8 (% 0) or more and 0.8. Between (% 0) and below, it is set as a fixed value in increments of 0.2 (% 0). FIG. 27A shows an example of the result of measuring the magnetic field dependence of electrical resistance at each strain. The direction of the external magnetic field at the time of measurement is added to the direction perpendicular to the magnetization direction of each bias layer in the plane. FIG. 27A shows that the RH loop shape changes depending on the value of applied strain. This indicates that the in-plane magnetic anisotropy of the magnetization free layer is changed by the inverse magnetostriction effect.

  27 (b) to 27 (d) show a strain sensing element 300 of the sixth embodiment with an external magnetic field fixed and a strain of −0.8 (% 0) or more and 0.8 (% 0) or less. The change of the electrical resistance when sweeping continuously between is shown. The distortion is swept from −0.8 (% 0) to 0.8 (% 0), and then from 0.8 (% 0) to −0.8 (% 0). These results show the strain sensor characteristics. In FIG. 27D, the evaluation is performed by applying an external magnetic field of 0 Oe.

  In the strain sensing element 300 of the embodiment, a high gauge factor can be obtained by applying an appropriate bias magnetic field. The external magnetic field can also be applied by providing a hard bias on the side wall of the strain sensing element. In the strain sensing element 300 of the sixth embodiment, evaluation is performed by simply applying an external magnetic field by a coil. From FIG. 27 (b) to FIG. 27 (d), the gauge factor of the sixth embodiment is estimated from the change in electrical resistance with respect to strain.

  The gauge factor is expressed by Equation (2) described above with reference to FIGS. 10 (a) to 10 (e). From FIG. 27B, in the sixth example, the gauge factor when the external magnetic field is 5 Oe is 2276. From FIG. 27C, in the sixth example, the gauge factor when the external magnetic field is 2 Oe is 4270. From FIG. 27D, in the sixth example, the gauge factor when the external magnetic field is 0 Oe is 4980. From this result, in the sixth example, when the bias magnetic field is 0 Oe, the maximum gauge factor (4980) is obtained.

  The gauge factor of the sixth embodiment is higher than the gauge factor of the fifth embodiment. In the sixth embodiment, since both the lower bias layer 110 and the upper bias layer 120 include a plurality of bias magnetic layers, the influence of the leakage magnetic field from the bias magnetic layer can be reduced. Can be confirmed. Thus, the number of bias layers is preferably a plurality of layers.

As a seventh example according to the embodiment, a strain sensing element 300 having the following structure is manufactured.
(Seventh embodiment)
Underlayer 50: Ta (1 nm) / Ru (2 nm)
Lower bias layer 110: Ir ₂₂ Mn ₇₈ (7 nm) / Fe ₅₀ Co ₅₀ (3 nm) / Cu (2.5 nm)
Lower magnetic layer 10 (first magnetization free layer): Fe ₈₀ B ₂₀ (4 nm) / Co ₄₀ Fe ₄₀ B ₂₀ (0.5 nm)
Intermediate layer 30: MgO (2 nm)
Upper magnetic layer 20 (second magnetization free layer): Co ₄₀ Fe ₄₀ B ₂₀ (0.5 nm) / Fe ₈₀ B ₂₀ (4 nm)
Upper bias layer 120: Cu (2.5 nm) / Fe ₅₀ Co ₅₀ (2 nm) / Ru (0.9 nm) / Fe ₅₀ Co ₅₀ (2 nm) / IrMn (7 nm)
Cap layer 70: Ta (2 nm) / Ru (5 nm)
The structure of the strain sensing element 300 of the seventh embodiment is the same as that of the strain sensing element 300a shown in FIG. The structure of the lower bias layer 110 is the same as that of the lower bias layer 110a shown in FIG. The lower bias layer 110 includes a lower bias pinning layer 42a / a lower first bias magnetic layer 111a / a lower isolation layer 43a. The structure of the upper bias layer 120 is the same as that of the upper bias layer 120a shown in FIG. The upper bias layer 120a is upper separation layer 43b / upper first bias magnetic layer 121a / upper first magnetic coupling layer 124a / upper second bias magnetic layer 121b / upper bias pinning layer 42b. The difference from the fifth embodiment is that Co ₄₀ Fe ₄₀ B ₂₀ (4 nm) is used for the lower magnetic layer 10 and the upper magnetic layer 20 in the fifth embodiment, whereas in the seventh embodiment, The lower magnetic layer 10 and the upper magnetic layer 20 are made of Co ₄₀ Fe ₄₀ B ₂₀ (0.5 nm) / Fe ₈₀ B ₂₀ (4 nm) which are turned upside down.

When the magnetic characteristics of the magnetization free layer of the seventh example including Fe ₄₀ B ₂₀ (0.5 nm) / Fe ₈₀ B ₂₀ (4 nm) were evaluated, the coercive force H _c was 3 Oe, and the magnetostriction constant was 26 ppm. is there. The coercive force of the seventh example is smaller than that of Co ₄₀ Fe ₄₀ B ₂₀ (4 nm) of the fifth example. The magnetostriction constant of the seventh embodiment is larger than the magnetostriction constant of the fifth embodiment. Thus, by using an amorphous magnetic layer containing an alloy containing Fe and B for the magnetization free layer, both low _Hc and high magnetostriction constant can be achieved.

FIG. 28A to FIG. 28D are graphs showing examples of results of strain sensor characteristics of the strain sensing element of the seventh example.
Similar to the fifth embodiment, the strain sensor characteristics are evaluated.
In the example shown in FIG. 28A, with respect to the strain sensing element 300 of the seventh embodiment having an element size of 20 μm × 20 μm, the strain applied to the strain sensing element 300 is −0.8 (% 0) or more and 0.8. Between (% 0) and below, it is set as a fixed value in increments of 0.2 (% 0). FIG. 28A shows an example of the result of measuring the magnetic field dependence of electrical resistance at each strain. The direction of the external magnetic field at the time of measurement is added to the direction perpendicular to the magnetization direction of each bias layer in the plane. FIG. 28A shows that the RH loop shape changes depending on the value of applied strain. This indicates that the in-plane magnetic anisotropy of the magnetization free layer is changed by the inverse magnetostriction effect.

  28 (b) to 28 (d) show a strain sensing element 300 of the seventh embodiment, in which the external magnetic field is fixed and the strain is −0.8 (% 0) or more and 0.8 (% 0) or less. The change of the electrical resistance when sweeping continuously between is shown. The distortion is swept from −0.8 (% 0) to 0.8 (% 0), and then from 0.8 (% 0) to −0.8 (% 0). These results show the strain sensor characteristics. In FIG. 28B, the evaluation is performed by applying an external magnetic field of 5 Oe. In FIG. 28C, evaluation is performed by applying an external magnetic field of 2 Oe. In FIG. 28D, evaluation is performed by applying an external magnetic field of 0 Oe.

  In the strain sensing element 300 of the embodiment, a high gauge factor can be obtained by applying an appropriate bias magnetic field. The external magnetic field can also be applied by providing a hard bias on the side wall of the strain sensing element. In the strain sensing element 300 of the seventh embodiment, an external magnetic field is simply applied by a coil for evaluation. From FIG. 28 (b) to FIG. 28 (d), the gauge factor of the seventh embodiment is estimated from the change in electrical resistance with respect to strain.

  The gauge factor is expressed by Equation (2) described above with reference to FIGS. 10 (a) to 10 (e). From FIG. 28B, in the seventh embodiment, the gauge factor when the external magnetic field is 5 Oe is 3086. From FIG. 28C, in the seventh example, the gauge factor when the external magnetic field is 2 Oe is 4418. From FIG. 28D, in the seventh embodiment, the gauge factor when the external magnetic field is 0 Oe is 5290. From this result, in the seventh example, the maximum gauge factor (5290) is obtained when the bias magnetic field is 0 Oe.

The gauge factor of the seventh embodiment is higher than the gauge factor of the fifth embodiment. This is because, in the seventh embodiment, the lower magnetic layer 10 and the upper magnetic layer 20 use a magnetization free layer containing an Fe—B alloy having both a low coercive force _Hc and a high magnetostriction constant.

FIG. 29A to FIG. 29D are schematic views for explaining another strain sensing element according to the embodiment.
In the embodiment described above, the bias direction applied from the lower bias layer 110 to the lower magnetic layer 10 (first magnetization free layer) is the bias applied from the upper bias layer 120 to the upper magnetic layer 20 (second magnetization free layer). The case where the direction is parallel or anti-parallel has been described. However, the direction is not limited to parallel / antiparallel. It is possible to apply a bias in any direction.

  For example, as shown in FIG. 29A, the relative angle between the bias direction of the lower bias layer 110b and the bias direction of the upper bias layer 120b can be set to 90 °. The bias direction is set in accordance with the two-stage annealing in the magnetic field as shown in FIGS. 29B and 29C and the materials used for the lower bias pinning layer 42a and the upper bias pinning layer 42b. It becomes possible by selection.

  About the antiferromagnetic material used for the lower bias pinning layer 42a and the upper bias pinning layer 42b, the temperature at which magnetization fixation occurs differs depending on the composition. For example, in the case of an ordered alloy material such as PtMn, the temperature at which magnetization fixation is performed is higher than that of a material that causes magnetization fixation even with irregularities such as IrMn. For example, as shown in FIGS. 29B and 29C, PtMn is used for the lower bias pinning layer 42a of the strain sensing element 300b shown in FIG. 29A and IrMn is used for the upper bias pinning layer 42b. A two-stage heat treatment in a magnetic field is performed. Then, in the 320 ° C.-10H annealing shown in FIG. 29B, the lower third bias magnetic layer 111c in contact with the lower bias pinning layer 42a is fixed to the lower right. The upper second bias magnetic layer 125b in contact with the upper bias pinning layer 42b is once fixed to the lower right.

  Thereafter, for example, when the direction of the magnetic field MF is changed by 250 ° C.-1H annealing shown in FIG. 29C, the magnetization 111 cm of the lower first bias magnetic layer 111c in contact with the lower bias pinning layer 42a remains to the lower right. Thus, it is possible to set such that the direction of the magnetization 125bm of the upper second bias magnetic layer 125b in contact with the upper bias pinning layer 42b faces the upper right. The orientations of the magnetizations 111 cm and 125 bm are maintained even after returning to room temperature as shown in FIG.

  Thus, the lower magnetic layer 10 (first magnetization free layer) and the upper magnetic layer 20 (second magnetization free layer) are selected depending on the annealing method in the magnetic field and the material selection of the lower bias pinning layer 42a and the upper bias pinning layer 42b. The direction of the bias to can be set arbitrarily. Here, as described above, when a tunnel type strain sensing element using an insulating layer is used for the intermediate layer 30, the bias direction to the lower magnetic layer 10 (first magnetization free layer) is set to the upper magnetic layer 20 (first magnetic layer). (2 magnetization free layer) is more preferably anti-parallel to the bias direction. Specifically, the relative angle between the bias direction toward the lower magnetic layer 10 (first magnetization free layer) and the bias direction toward the upper magnetic layer 20 (second magnetization free layer) is 90 ° or more and 270. It is preferable to set it to ° or less, and more preferable to set it to 135 ° or more and 225 ° or less.

  On the other hand, for the purpose of widening the dynamic range of strain changing resistance, the bias direction to the lower magnetic layer 10 (first magnetization free layer), the bias direction to the upper magnetic layer 20 (second magnetization free layer), The relative angle between is preferably 45 ° or more and 135 ° or less.

Although not shown in the figure, the setting of an arbitrary bias direction as shown in FIGS. 29 (a) to 29 (d) is shown in FIGS. 16 (a) to 16 (d) and FIGS. Similarly to the relationship between 17 (d) and FIG. 17, a bias layer that does not use a bias pinning layer is also possible.
Also in the second embodiment, a buried insulating layer and a hard bias around the strain sensing element can be used as in FIG. 18 of the first embodiment and FIG. 19 of the first embodiment.

  FIG. 30 is a schematic plan view showing an example of the bias direction of each bias layer and the bias direction of the hard bias in the second embodiment.

  In the example shown in FIG. 30, the bias direction of the upper bias layer 120 is set antiparallel to the bias direction of the lower bias layer 110. The magnetic field bias direction of the hard bias layer 83 with respect to the upper first bias magnetic layer 125a is set to 90 ° (or 270 °). The magnetic field bias direction of the hard bias layer 83 with respect to the lower first bias magnetic layer 111a is set to 90 ° (or 270 °).

  The initial magnetization 10mf (the direction of the bias 10p) of the lower magnetic layer 10 (first magnetization free layer) is due to the competition between the bias 10pb from the lower first bias magnetic layer 111a and the magnetic field bias 10ph from the hard bias layer 83. , Between 0 ° and 90 °, for example, 45 °. The initial magnetization 20mf (the direction of the bias 20p) of the upper magnetic layer 20 (second magnetization free layer) is due to the competition between the bias 20pb from the upper first bias magnetic layer 125a and the magnetic field bias 20ph from the hard bias layer 83. , Between 90 ° and 180 °, for example, 135 °. Relative relationship between the initial magnetization 10 mf (the direction of bias 10 p) of the lower magnetic layer 10 (first magnetization free layer) and the initial magnetization 20 mf (the direction of bias 20 p) of the upper magnetic layer 20 (second magnetization free layer) The angle is set to 90 °, for example.

  Thus, when the hard bias layer 83 is provided in the strain sensing element of the embodiment including the lower bias layer 110 and the upper bias layer 120, the initial magnetization 10mf (the direction of the bias 10p) of the lower magnetic layer 10 (first magnetization free layer). ) And the initial magnetization 20mf (direction of the bias 20p) of the upper magnetic layer 20 (second magnetization free layer) is preferably set to 90 ° or more and 270 ° or less, and 135 ° or more and 225 It is more preferable to set the angle below. Here, as indicated by arrows A103 and A104 in FIG. 30, the direction of strain applied to the strain sensing element of the embodiment is parallel or perpendicular to the direction of magnetization of the bias magnetic layers of both bias layers. Furthermore, a monotonically increasing or monotonically decreasing electrical resistance change can be obtained in the 90 ° range, which is the dynamic range of magnetization in which the magnetization free layer rotates due to strain. Therefore, it is preferable.

(Third embodiment)
FIG. 31 is a schematic perspective view illustrating a pressure sensor according to the third embodiment.
As illustrated in FIG. 31, the pressure sensor 200 according to the embodiment includes a support unit 201, a substrate 210, and a strain sensing element 100. The pressure sensor 200 according to the embodiment may include a strain sensing element 300 according to the second embodiment instead of the strain sensing element 100 according to the first embodiment.

  The substrate 210 is supported by the support unit 201. The substrate 210 has, for example, a flexible region. The substrate 210 is, for example, a diaphragm. The substrate 210 may be integrated with the support portion 201 or may be a separate body. The substrate 210 may be made of the same material as that of the support portion 201, or may be made of a material different from that of the support portion 201. A part of the support part 201 may be removed, and the thin part of the support part 201 may be the substrate 210.

  The thickness of the substrate 210 is thinner than the thickness of the support portion 201. In the case where the same material is used for the substrate 210 and the support portion 201 and they are integrated, the thin portion becomes the substrate 210 and the thick portion becomes the support portion 201.

  The support part 201 may have a through hole 201h that penetrates the support part 201 in the thickness direction, and the substrate 210 may be provided so as to cover the through hole 201h. At this time, for example, the film of the material to be the substrate 210 may also extend on a portion other than the through hole 201h of the support portion 201. At this time, the portion of the material film that becomes the substrate 210 that overlaps the through-hole 201 h becomes the substrate 210.

  The substrate 210 has an outer edge 210r. In the case where the same material is used for the substrate 210 and the support portion 201 and they are integrated, the outer edge of the thin portion becomes the outer edge 210r of the substrate 210. When the support part 201 has the through-hole 201h which penetrates the support part 201 in thickness direction, and the board | substrate 210 is provided so that the through-hole 201h may be covered, out of the film | membrane of the material used as the board | substrate 210 Thus, the outer edge of the portion overlapping with the through hole 201 h becomes the outer edge 210 r of the substrate 210.

  The support unit 201 may continuously support the outer edge 210r of the substrate 210, or may support a part of the outer edge 210r of the substrate 210.

  The strain sensing element 100 is provided on the substrate 210. For example, the strain sensing element 100 is provided on a part of the substrate 210. In this example, a plurality of strain sensing elements 100 are provided on the substrate 210. The number of strain sensing elements provided on the film part may be one.

  In the pressure sensor 200 illustrated in FIG. 31, a first wiring 221 and a second wiring 222 are provided. The first wiring 221 is connected to the strain sensing element 100. The second wiring 222 is connected to the strain sensing element 100. For example, an interlayer insulating film is provided between the first wiring 221 and the second wiring 222, and the first wiring 221 and the second wiring 222 are electrically insulated. A voltage is applied between the first wiring 221 and the second wiring 222, and this voltage is applied to the strain sensing element 100 via the first wiring 221 and the second wiring 222. When pressure is applied to the pressure sensor 200, the substrate 210 is deformed. In the strain sensing element 100, the electrical resistance R changes with the deformation of the substrate 210. By detecting the change in the electric resistance R through the first wiring 221 and the second wiring 222, the pressure can be detected.

  For the support part 201, for example, a plate-like substrate can be used. For example, a cavity (through hole 201h) is provided inside the substrate.

  For the support portion 201, for example, a semiconductor material such as silicon, a conductive material such as metal, or an insulating material can be used. The support unit 201 may include, for example, silicon oxide or silicon nitride. The inside of the cavity (through hole 201h) is, for example, in a reduced pressure state (vacuum state). The cavity (through hole 201h) may be filled with a gas such as air or a liquid. The interior of the cavity (through hole 201h) is designed so that the substrate 210 can be bent. The inside of the hollow portion (through hole 201h) may be connected to the outside atmosphere.

  A substrate 210 is provided on the cavity (through hole 201h). For the substrate 210, for example, a part of the support portion 201 is thinly processed and used. The thickness of the substrate 210 (length in the Z-axis direction) is thinner than the thickness of the support portion 201 (length in the Z-axis direction).

  When pressure is applied to the substrate 210, the substrate 210 is deformed. This pressure corresponds to the pressure that the pressure sensor 200 should detect. The applied pressure includes pressure by sound waves or ultrasonic waves. In the case where pressure due to sound waves or ultrasonic waves is detected, the pressure sensor 200 functions as a microphone.

  For example, an insulating material is used for the substrate 210. The substrate 210 includes, for example, at least one of silicon oxide, silicon nitride, and silicon oxynitride. For the substrate 210, for example, a semiconductor material such as silicon may be used. For example, a metal material may be used for the substrate 210.

  The thickness of the substrate 210 is, for example, not less than 0.1 micrometer (μm) and not more than 3 μm. This thickness is preferably 0.2 μm or more and 1.5 μm or less. For the substrate 210, for example, a stacked body of a silicon oxide film having a thickness of 0.2 μm and a silicon film having a thickness of 0.4 μm may be used.

32A to 32D are schematic plan views showing the relationship between the shape of the substrate and the direction of the bias layer of the first embodiment.
FIG. 32A is a schematic plan view showing the substrate 210. FIG. 32B and FIG. 32C are schematic enlarged views of the area A201 shown in FIG. FIG. 32D is a schematic enlarged view in which a portion where the strain sensing element 100 is provided is enlarged.

  When the substrate 210 is a circular diaphragm, the strain ε is applied in the radiation direction from the center of gravity. As shown in FIGS. 32A and 32B, for example, the magnetization 11m of the first magnetization fixed layer 11 and the magnetization 41am of the first bias magnetic layer 41a are perpendicular to the direction of the strain ε. can do. In other words, as shown in FIGS. 32 (b) and 32 (d), the magnetization 11m of the first magnetization fixed layer 11 and the magnetization 41am of the first bias magnetic layer 41a are represented by the outer edge 210r and the strain sensing element 100. The angle formed by the first straight line 181 that connects the center of gravity 100gc of the two at the shortest distance can be vertical (90 °). For example, if this angle is not less than 75 ° and not more than 105 °, the same characteristics as in the case of 0 ° can be obtained. Alternatively, as shown in FIGS. 32A and 32B, the magnetization 11m of the first magnetization fixed layer 11 and the magnetization 41am of the first bias magnetic layer 41a are set to the center of gravity 210gc of the substrate 210 and the strain detection. The angle between the center of gravity 100gc of the element 100 and the second straight line 182 connecting the shortest distance can be vertical (90 °). For example, if this angle is not less than 75 ° and not more than 105 °, the same characteristics as in the case of 0 ° can be obtained. The direction of the hard bias 83m can be set so as to be shifted from the parallel direction and the vertical direction with respect to the direction of the strain ε. For example, it can be 45 ° or 135 °. By setting in this way, the initial magnetization 20mf (the direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) can be shifted from the direction parallel to and perpendicular to the direction of the strain ε. In contrast, a change in electrical resistance R can be obtained. Preferably, the initial magnetization 20mf (direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) is adjusted by the bias 20pb from the first bias magnetic layer 41a and the magnetic field bias 20ph from the hard bias layer 83. Thus, it is preferable that the initial magnetization 20mf (the direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) is about 45 ° or 135 ° with respect to the direction of the strain ε.

  As shown in FIGS. 32A and 32C, for example, the magnetization 11m of the first magnetization fixed layer 11 and the magnetization 41am of the first bias magnetic layer 41a are made parallel to the direction of the strain ε. Can do. In other words, as shown in FIGS. 32 (c) and 32 (d), the magnetization 11m of the first magnetization fixed layer 11 and the magnetization 41am of the first bias magnetic layer 41a are composed of the outer edge 210r and the strain sensing element 100. The angle formed by the first straight line 181 that connects the center of gravity 100gc of the two at the shortest distance can be parallel (0 °). For example, if this angle is 0 ° or more and 15 ° or less, the same characteristics as in the case of 0 ° can be obtained. Alternatively, as shown in FIGS. 32A and 32C, the magnetization 11am of the first magnetization fixed layer 11, the magnetization 41am of the first bias magnetic layer 41a, and the center of gravity 210gc of the substrate 210 and strain detection The angle formed by the second straight line 182 connecting the center of gravity 100gc of the element 100 with the shortest distance can be parallel (0 °). For example, if this angle is 0 ° or more and 15 ° or less, the same characteristics as in the case of 0 ° can be obtained. The direction of the hard bias 83m can be shifted from the parallel direction and the vertical direction with respect to the direction of the strain ε. For example, it can be 45 ° or 135 °. By setting in this way, the initial magnetization 20mf (the direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) can be shifted from the direction parallel to and perpendicular to the direction of the strain ε. In contrast, a change in electrical resistance R can be obtained. Preferably, the initial magnetization 20mf (direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) is adjusted by the bias 20pb from the first bias magnetic layer 41a and the magnetic field bias 20ph from the hard bias layer 83. Thus, the initial magnetization 20mf (the direction of the bias 20p) of the second magnetic layer 20 (magnetization free layer) is set to about 45 ° or about 135 ° with respect to the direction of the strain ε.

  In FIGS. 32A to 32D, an example in which the substrate 210 is a circular diaphragm is shown. However, it is considered that a strain ε is generated in the vertical direction with respect to the outer edge 210r even in other shapes of diaphragms. The above magnetization direction can be designed. In the case where the outer edge 210r is not a straight line but a curve, the direction perpendicular to the outer edge 210r, which can be regarded as a straight line in a minute range, can be considered as a direction in which distortion occurs.

FIG. 33A to FIG. 33D are schematic plan views showing the relationship between the shape of the substrate and the direction of the bias layer of the second embodiment.
FIG. 33A is a schematic plan view showing the substrate 210. FIG. 33B and FIG. 33C are schematic enlarged views of the region A202 shown in FIG. FIG. 33 (d) is a schematic enlarged view in which a portion where the strain sensing element 100 is provided is enlarged.

  When the substrate 210 is a circular diaphragm, the strain ε is applied in the radiation direction from the center of gravity. As shown in FIGS. 33A and 33B, for example, the magnetization 111am of the lower first bias magnetic layer 111a and the magnetization 121am of the upper first bias magnetic layer 121a with respect to the direction of the strain ε. It can be vertical. In other words, as shown in FIGS. 33 (b) and 33 (d), the magnetization 111am of the lower first bias magnetic layer 111a and the magnetization 121am of the upper first bias magnetic layer 121a are converted into the outer edge 210r and the strain detection. The angle formed by the first straight line 181 connecting the center of gravity 100gc of the element 100 with the shortest distance can be vertical (90 °). For example, if this angle is not less than 75 ° and not more than 105 °, the same characteristics as in the case of 90 ° can be obtained. Alternatively, as shown in FIGS. 33A and 33B, the magnetization 111am of the lower first bias magnetic layer 111a and the magnetization 121am of the upper first bias magnetic layer 121a are distorted with the center of gravity 210gc of the substrate 210. The angle formed by the second straight line 182 connecting the center of gravity 100gc of the sensing element 100 with the shortest distance can be vertical (90 °). For example, if this angle is not less than 75 ° and not more than 105 °, the same characteristics as in the case of 90 ° can be obtained. The direction of the hard bias 83m can be made parallel to the direction of the strain ε, for example. By setting in this way, the initial magnetization 10mf (the direction of the bias 10p) of the lower magnetic layer 10 (first magnetization free layer) and the initial magnetization 20mf (the direction of the bias 20p) of the upper magnetic layer 20 (second magnetization free layer). ) Can be shifted from the direction parallel to and perpendicular to the direction of strain ε, and a change in electrical resistance R can be obtained for positive and negative pressures. Preferably, the lower magnetic layer 10 (the first magnetic layer bias 10pb from the lower first bias magnetic layer 111a, the bias 20pb from the upper first bias magnetic layer 121a, and the magnetic field biases 10ph and 20ph from the hard bias layer 83 are preferably formed. The lower magnetic layer 10 (first magnetization free layer) is adjusted by adjusting the initial magnetization 10 mf (bias 10 p direction) of the magnetization free layer and the initial magnetization 20 mf (bias 20 p direction) of the upper magnetic layer 20 (second magnetization free layer). Layer) initial magnetization 10 mf (direction of bias 10 p) and upper magnetic layer 20 (second magnetization free layer) 20 mf (direction of bias 20 p) and the relative angle between the direction of strain ε, for example, , Larger than 0 ° and smaller than 90 °. For example, it can be around 45 °.

  As shown in FIGS. 33A and 33C, for example, the magnetization 111am of the lower first bias magnetic layer 111a and the magnetization 121am of the upper first bias magnetic layer 121a with respect to the direction of the strain ε. Can be parallel. In other words, as shown in FIGS. 33 (c) and 33 (d), the magnetization 111am of the lower first bias magnetic layer 111a and the magnetization 121am of the upper first bias magnetic layer 121a are converted into the outer edge 210r and the strain detection. The angle formed by the first straight line 181 connecting the center of gravity 100gc of the element 100 with the shortest distance can be parallel (0 °). For example, if this angle is 0 ° or more and 15 ° or less, the same characteristics as in the case of 0 ° can be obtained. Alternatively, as shown in FIGS. 33A and 33C, the magnetization 111am of the lower first bias magnetic layer 111a, the magnetization 121am of the upper first bias magnetic layer 121a, and the center of gravity 210gc of the substrate 210, The angle formed by the second straight line 182 connecting the center of gravity 100gc of the strain sensing element 100 with the shortest distance can be made parallel (0 °). For example, if this angle is 0 ° or more and 15 ° or less, the same characteristics as in the case of 0 ° can be obtained. The direction of the hard bias 83m can be perpendicular to the direction of the strain ε. By setting in this way, the initial magnetization 10mf (the direction of the bias 10p) of the lower magnetic layer 10 (first magnetization free layer) and the initial magnetization 20mf (the direction of the bias 20p) of the upper magnetic layer 20 (second magnetization free layer). ) Can be shifted from the direction parallel to and perpendicular to the direction of strain ε, and a change in electrical resistance R can be obtained for positive and negative pressures. Preferably, the lower magnetic layer 10 (the first magnetic layer bias 10pb from the lower first bias magnetic layer 111a, the bias 20pb from the upper first bias magnetic layer 121a, and the magnetic field biases 10ph and 20ph from the hard bias layer 83 are preferably formed. The lower magnetic layer 10 (first magnetization free layer) is adjusted by adjusting the initial magnetization 10 mf (bias 10 p direction) of the magnetization free layer and the initial magnetization 20 mf (bias 20 p direction) of the upper magnetic layer 20 (second magnetization free layer). Layer) initial magnetization 10 mf (direction of bias 10 p) and upper magnetic layer 20 (second magnetization free layer) 20 mf (direction of bias 20 p) and the relative angle between the direction of strain ε, for example, , Larger than 0 ° and smaller than 90 °. For example, it can be around 45 °.

  33 (a) to 33 (d) show examples in which the substrate 210 is a circular diaphragm, but it is considered that a strain ε is generated in the vertical direction with respect to the outer edge 210r even in other shapes of diaphragms. The above magnetization direction can be designed. In the case where the outer edge 210r is not a straight line but a curved line, the direction perpendicular to the outer edge 210r, which can be regarded as a straight line in a minute range, can be considered as a direction in which distortion occurs.

FIG. 34A and FIG. 34B are schematic views illustrating another pressure sensor according to the third embodiment.
As shown in FIGS. 34A and 34B, a plurality of strain sensing elements 100 may be arranged on the substrate 210. That is, the pressure sensor 200b shown in FIGS. 34A and 34B includes a first strain sensing element unit 101, a second strain sensing element unit 102, a third strain sensing element unit 103, and a fourth strain sensing element unit 103. Strain detection element unit 104. The first strain sensing element unit 101, the second strain sensing element unit 102, the third strain sensing element unit 103, and the fourth strain sensing element unit 104 include a plurality of strain sensing elements 100. Obtaining the same change in electrical resistance R with respect to pressure by the plurality of strain sensing elements 100 can increase the SN ratio by connecting the plurality of strain sensing elements 100 in series and parallel, as will be described later. .

  In the example of FIGS. 34 (a) and 34 (b), a plurality of strain sensing elements 100 are arranged, but one may be used. In the example of FIG. 34A and FIG. 34B, variations of the arrangement on the circular substrate 210 are shown.

It is sufficient that the strain sensing element 100 has an extremely small size.
Therefore, the area of the strain sensing element 100 can be made sufficiently smaller than the area of the substrate 210 that is deformed by pressure. For example, the area of the strain sensing element 100 can be 1/5 or less of the area of the substrate 210.

  For example, when the diameter of the substrate 210 is about 60 μm, the dimension of the strain sensing element 100 can be 12 μm or less. For example, when the diameter of the substrate 210 is about 600 μm, the dimension of the strain sensing element 100 can be 120 μm or less.

  In this case, considering the processing accuracy of the strain sensing element 100, the dimensions of the strain sensing element 100 do not need to be excessively small. Therefore, the dimension of the strain sensing element 100 can be set to, for example, 0.05 μm or more and 30 μm or less.

  FIG. 34A illustrates the case where the planar shape of the substrate 210 is a circle, but the planar shape of the substrate 210 is not limited to a circle. The planar shape of the substrate 210 can be, for example, an oval, a regular polygon such as a square or a rectangle.

  The plurality of strain sensing elements 100 provided on the substrate 210 can be connected in series. When the number of strain sensing elements 100 in which a plurality of strain sensing elements 100 are connected in series is N, the obtained electrical signal is N times that when the number of strain sensing elements 100 is one. On the other hand, thermal noise and Schottky noise become N1 / 2 times. That is, the SN ratio (signal-noise ratio: SNR) is N1 / 2 times. By increasing the number N of strain sensing elements 100 connected in series, the SN ratio can be improved without increasing the size of the substrate 210.

The bias voltage applied to one strain sensing element 100 is, for example, 50 millivolts (mV) or more and 150 mV or less. When N strain sensing elements 100 are connected in series, the bias voltage is 50 mV × N or more and 150 mV × N or less. For example, when the number N of strain sensing elements 100 connected in series is 25, the bias voltage is 1 V or more and 3.75 V or less.
When the value of the bias voltage is 1 V or more, it is easy to design an electric circuit for processing an electric signal obtained from the strain sensing element 100, which is practically preferable.

  When the bias voltage (inter-terminal voltage) exceeds 10 V, it is not desirable in an electric circuit that processes an electric signal obtained from the strain sensing element 100. In the embodiment, the number N of strain sensing elements 100 connected in series and the bias voltage are set so as to be in an appropriate voltage range.

  For example, the voltage when a plurality of strain sensing elements 100 are electrically connected in series is preferably 1 V or more and 10 V or less. For example, the voltage applied between the terminals of the plurality of strain sensing elements 100 electrically connected in series (between one terminal and the other terminal) is 1 V or more and 10 V or less. .

In order to generate this voltage, when the bias voltage applied to one strain sensing element 100 is 50 mV, the number N of strain sensing elements 100 connected in series is preferably 20 mV or more and 200 mV or less. When the bias voltage applied to one strain sensing element 100 is 150 mV, the number N of strain sensing elements 100 connected in series is preferably 6 or more and 200 or less, and more preferably 7 or more and 66 or less. More preferred.
At least some of the plurality of strain sensing elements 100 may be electrically connected in parallel.

  As shown in FIG. 34B, a plurality of strain sensing elements 100 may be connected such that the plurality of strain sensing elements 100 form a Wheatstone bridge circuit. Thereby, for example, temperature compensation of detection characteristics can be performed.

FIG. 35A to FIG. 35C are schematic perspective views illustrating the pressure sensor according to the third embodiment.
FIG. 35A to FIG. 35C show examples of connection of a plurality of strain sensing elements 100.
As shown in FIG. 35A, when the plurality of strain sensing elements 100 are electrically connected in series, the first electrode E1 (for example, the second wiring 222) and the second electrode E2 (for example, the first electrode) The strain sensing element 100 and the via contact 230 are provided between the wiring 221). Thereby, the energization direction becomes one direction. The current passed through the plurality of strain sensing elements 100 is downward or upward. In this connection, the signal / noise characteristics of the plurality of strain sensing elements 100 can be made close to each other.

  As illustrated in FIG. 35B, the strain sensing element 100 is disposed between the first electrode E1 and the second electrode E2 without the via contact 230 being provided. In this example, the directions of currents passed through the two adjacent strain sensing elements 100 are opposite to each other. In this connection, the density of the arrangement of the plurality of strain sensing elements 100 is high.

  As shown in FIG. 35C, a plurality of strain sensing elements 100 are provided between one first electrode E1 and one second electrode E2. The plurality of strain sensing elements 100 are connected in parallel.

Hereinafter, an example of the manufacturing method of the pressure sensor according to the embodiment will be described. The following is an example of a method for manufacturing a pressure sensor.
FIG. 36A to FIG. 36E are schematic cross-sectional views in order of the processes, illustrating the manufacturing direction of the pressure sensor according to the embodiment.

As shown in FIG. 36A, a thin film 242 is formed on a base 241 (for example, a Si substrate). The base 241 serves as the support unit 201. The thin film 242 becomes the substrate 210.
For example, a thin film 242 of SiO _x / Si is formed on a Si substrate by sputtering. As the thin film 242, a SiO _x single layer, a SiN single layer, or a metal layer such as Al may be used. As the thin film 242, a flexible plastic material such as polyimide or paraxylylene-based polymer may be used. An SOI (Silicon On Insulator) substrate may be used as the base 241 and the thin film 242. In SOI, for example, a laminated film of SiO ₂ / Si is formed on a Si substrate by bonding the substrates.

  As shown in FIG. 36B, the second wiring 222 is formed. In this step, a conductive film to be the second wiring 222 is formed, and the conductive film is processed by photolithography and etching. When the periphery of the second wiring 222 is embedded with an insulating film, a lift-off process may be applied. In the lift-off process, for example, after the pattern of the second wiring 222 is etched, before the resist is peeled off, an insulating film is formed on the entire surface, and then the resist is removed.

  As shown in FIG. 36C, the strain sensing element 100 is formed. In this step, a laminated body that becomes the strain sensing element 100 is formed, and the laminated body is processed by photolithography and etching. When embedding the sidewall of the laminate of the strain sensing element 100 with the insulating layer 81, a lift-off process may be applied. In the lift-off process, for example, after processing the laminated body, before the resist is peeled off, the insulating layer 81 is formed over the entire surface, and then the resist is removed.

  As shown in FIG. 36D, the first wiring 221 is formed. In this step, a conductive film to be the first wiring 221 is formed, and the conductive film is processed by photolithography and etching. When the periphery of the first wiring 221 is embedded with an insulating film, a lift-off process may be applied. In the lift-off process, an insulating film is formed over the entire surface after the first wiring 221 is processed and before the resist is removed, and then the resist is removed.

As shown in FIG. 36E, etching is performed from the back surface of the base 241 to form the cavity 201a. Thereby, the board | substrate 210 and the support part 201 are formed. For example, when a SiO _x / Si laminated film is used as the thin film 242 to be the substrate 210, the base 241 is deeply drilled from the back surface (lower surface) to the front surface (upper surface) of the thin film 242. Thereby, the cavity part 201a is formed. In forming the cavity 201a, for example, a double-sided aligner exposure apparatus can be used. Thus, the hole pattern of the resist can be patterned on the back surface according to the position of the strain detection element 100 on the front surface.

In etching the Si substrate, for example, a Bosch process using RIE can be used. In the Bosch process, for example, an etching process using SF ₆ gas and a deposition process using C ₄ F ₈ gas are repeated. Thereby, etching is selectively performed in the depth direction (Z-axis direction) of the base 241 while suppressing the etching of the side wall of the base 241. For example, a SiO _x layer is used as an etching end point. That is, the etching is terminated using an SiO _x layer having a different etching selectivity than Si. The SiO _x layer that functions as an etching stopper layer may be used as a part of the substrate 210. The SiO _x layer may be removed after the etching, for example, by treatment with anhydrous hydrogen fluoride and alcohol.

  In this way, the pressure sensor 200 according to the embodiment is formed. Other pressure sensors according to the embodiment can be manufactured by the same method.

(Fourth embodiment)
FIG. 37A to FIG. 37C are schematic views illustrating the pressure sensor according to the embodiment. FIG. 37A is a schematic perspective view, and FIGS. 37B and 37C are block diagrams illustrating the pressure sensor 640.

  As shown in FIGS. 37A and 37B, the pressure sensor 640 includes a base 671, a detection unit 650, a semiconductor circuit unit 630, an antenna 615, an electrical wiring 616, a transmission circuit 617, and a reception circuit 617r. Is provided.

The antenna 615 is electrically connected to the semiconductor circuit portion 630 through the electric wiring 616.
The transmission circuit 617 wirelessly transmits data based on the electrical signal flowing through the detection unit 650. At least part of the transmission circuit 617 can be provided in the semiconductor circuit portion 630.

  The receiving circuit 617r receives a control signal from the electronic device 618d. At least a part of the reception circuit 617r can be provided in the semiconductor circuit portion 430. If the receiving circuit 617r is provided, for example, the operation of the pressure sensor 640 can be controlled by operating the electronic device 618d.

  As shown in FIG. 37B, the transmission circuit 617 can include, for example, an AD converter 617a connected to the detection unit 650 and a Manchester encoding unit 617b. A switching unit 617c can be provided to switch between transmission and reception. In this case, a timing controller 617d is provided, and switching in the switching unit 617c can be controlled by the timing controller 617d. Furthermore, a data correction unit 617e, a synchronization unit 617f, a determination unit 617g, and a voltage controlled oscillator 617h (VCO; Voltage Controlled Oscillator) can be provided.

As shown in FIG. 37C, an electronic device 618d used in combination with the pressure sensor 640 is provided with a receiving unit 618. As the electronic device 618d, for example, an electronic device such as a portable terminal can be exemplified.
In this case, the pressure sensor 640 including the transmission circuit 617 and the electronic device 618d including the reception unit 618 can be used in combination.

  The electronic device 618d includes a Manchester encoding unit 617b, a switching unit 617c, a timing controller 617d, a data correction unit 617e, a synchronization unit 617f, a determination unit 617g, a voltage controlled oscillator 617h, a storage unit 618a, a central processing unit 618b (CPU; Central). Processing Unit) can be provided.

In this example, the pressure sensor 640 further includes a fixing portion 667. The fixing part 667 fixes the film part 664 to the base part 671. The fixing part 667 can be thicker than the film part 664 so that the fixing part 667 is not easily bent even when an external pressure is applied.
For example, the fixing portions 667 can be provided at equal intervals on the periphery of the film portion 664.
The fixing portion 667 may be provided so as to continuously surround the entire periphery of the film portion 664.
The fixing portion 667 can be formed from the same material as that of the base portion 671, for example. In this case, the fixing portion 667 can be formed from, for example, silicon.
For example, the fixing portion 667 can be formed of the same material as the material of the film portion 664.

The example of the manufacturing method of the pressure sensor which concerns on embodiment is demonstrated.
38 (a), 38 (b), 39 (a), 39 (b), 40 (a), 40 (b), 41 (a), 41 (b), and 42. (A), 42 (b), 43 (a), 43 (b), 44 (a), 44 (b), 45 (a), 45 (b), 46 (a). 46 (b), FIG. 47 (a), FIG. 47 (b), FIG. 48 (a), FIG. 48 (b), FIG. 49 (a), and FIG. 49 (b) are pressures according to the embodiment. It is a schematic diagram which illustrates the manufacturing method of a sensor.

  FIGS. 38 (a) to 49 (a) are schematic plan views, and FIGS. 38 (b) to 49 (b) are schematic cross-sectional views.

  As shown in FIGS. 38A and 38B, a semiconductor layer 512 </ b> M is formed on the surface portion of the semiconductor substrate 531. Subsequently, an element isolation insulating layer 512I is formed on the upper surface of the semiconductor layer 512M. Subsequently, a gate 512G is formed over the semiconductor layer 512M via an insulating layer (not shown). Subsequently, the source 512S and the drain 512D are formed on both sides of the gate 512G, whereby the transistor 532 is formed. Subsequently, an interlayer insulating film 514a is formed thereon, and further an interlayer insulating film 514b is formed.

  Subsequently, a trench and a hole are formed in part of the interlayer insulating films 514a and 514b in a region to be a non-cavity. Subsequently, a conductive material is embedded in the holes to form connection pillars 514c to 514e. In this case, for example, the connection pillar 514c is electrically connected to the source 512S of one transistor 532, and the connection pillar 514d is electrically connected to the drain 512D. For example, the connection pillar 514e is electrically connected to the source 512S of another transistor 532. Subsequently, a conductive material is embedded in the trench to form wiring portions 514f and 514g. The wiring portion 514f is electrically connected to the connection pillar 514c and the connection pillar 514d. The wiring portion 514g is electrically connected to the connection pillar 514e. Subsequently, an interlayer insulating film 514h is formed over the interlayer insulating film 514b.

  As shown in FIGS. 39A and 39B, an interlayer insulating film 514i made of silicon oxide (SiO 2) is formed on the interlayer insulating film 514h by using, for example, a CVD (Chemical Vapor Deposition) method. To do. Subsequently, a hole is formed in a predetermined position of the interlayer insulating film 514i, a conductive material (for example, a metal material) is embedded, and the upper surface is planarized using a CMP (Chemical Mechanical Polishing) method. Thereby, the connection pillar 514j connected to the wiring part 514f and the connection pillar 514k connected to the wiring part 514g are formed.

  As shown in FIGS. 40A and 40B, a recess is formed in a region to be the cavity 570 of the interlayer insulating film 514i, and a sacrificial layer 514l is embedded in the recess. The sacrificial layer 514l can be formed using, for example, a material that can be formed at a low temperature. A material that can be formed at a low temperature is, for example, silicon germanium (SiGe).

As shown in FIGS. 41A and 41B, an insulating film 561bf to be a film portion 564 is formed on the interlayer insulating film 514i and the sacrificial layer 514l. The insulating film 561bf can be formed using, for example, silicon oxide (SiO ₂ ). A plurality of holes are provided in the insulating film 561bf, and a conductive material (for example, a metal material) is embedded in the plurality of holes to form connection pillars 561fa and connection pillars 562fa. The connection pillar 561fa is electrically connected to the connection pillar 514k, and the connection pillar 562fa is electrically connected to the connection pillar 514j.

  As shown in FIGS. 42A and 42B, a conductive layer 561f to be the wiring 557 is formed over the insulating film 561bf, the connection pillar 561fa, and the connection pillar 562fa.

  As shown in FIGS. 43A and 43B, a laminated film 550f is formed on the conductive layer 561f.

As shown in FIGS. 44A and 44B, the laminated film 550f is processed into a predetermined shape, and an insulating film 565f to be the insulating layer 565 is formed thereon. The insulating film 565f can be formed using, for example, silicon oxide (SiO ₂ ) or the like.

  As shown in FIGS. 45A and 45B, part of the insulating film 565f is removed, and the conductive layer 561f is processed into a predetermined shape. Thereby, the wiring 557 is formed. At this time, part of the conductive layer 561f becomes a connection pillar 562fb electrically connected to the connection pillar 562fa. Further, an insulating film 566f to be the insulating layer 566 is formed thereon.

  As shown in FIGS. 46A and 46B, an opening 566p is formed in the insulating film 566f. As a result, the connection pillar 562fb is exposed.

  As shown in FIGS. 47A and 47B, a conductive layer 562f to be the wiring 558 is formed on the upper surface. A part of the conductive layer 562f is electrically connected to the connection pillar 562fb. As shown in FIGS. 48A and 48B, the conductive layer 562f is processed into a predetermined shape. Thereby, the wiring 558 is formed. The wiring 558 is electrically connected to the connection pillar 562fb.

  As shown in FIGS. 49A and 49B, an opening 566o having a predetermined shape is formed in the insulating film 566f. The insulating film 561bf is processed through the opening 566o, and the sacrificial layer 514l is removed through the opening 566o. Thereby, the cavity 570 is formed. The removal of the sacrificial layer 514l can be performed using, for example, a wet etching method.

In the case where the fixing portion 567 is ring-shaped, for example, the space between the edge of the non-cavity portion above the cavity portion 570 and the film portion 564 is filled with an insulating film.
A pressure sensor is formed as described above.

(Fifth embodiment)
FIG. 50 is a schematic plan view illustrating a microphone according to the fourth embodiment.
As shown in FIG. 50, the microphone 410 includes an arbitrary pressure sensor (for example, the pressure sensor 200) according to each of the above-described embodiments and a pressure sensor according to a modification thereof. In the following, a microphone 410 having the pressure sensor 200 is illustrated as an example.

Microphone 410 is incorporated at the end of portable information terminal 420. For example, the substrate 210 of the pressure sensor 200 provided in the microphone 410 can be substantially parallel to the surface of the portable information terminal 420 on which the display unit 421 is provided. Note that the arrangement of the substrate 210 is not limited to that illustrated, but can be changed as appropriate.
Since the microphone 410 includes the pressure sensor 200 and the like, the microphone 410 can be highly sensitive to a wide range of frequencies.

  In addition, although the case where the microphone 410 was incorporated in the portable information terminal 420 was illustrated, it is not necessarily limited to this. The microphone 410 can be incorporated into, for example, an IC recorder or a pin microphone.

(Sixth embodiment)
The embodiment relates to an acoustic microphone using the pressure sensor of each of the above embodiments.
FIG. 51 is a schematic cross-sectional view illustrating an acoustic microphone according to the fifth embodiment.
The acoustic microphone 430 according to the embodiment includes a printed circuit board 431, a cover 433, and the pressure sensor 200. The printed circuit board 431 includes a circuit such as an amplifier. The cover 433 is provided with an acoustic hole 435. The sound 439 enters the cover 433 through the acoustic hole 435.

  As the pressure sensor 200, any of the pressure sensors described in relation to the above embodiments and modifications thereof are used.

The acoustic microphone 430 is sensitive to sound pressure. By using the highly sensitive pressure sensor 200, a highly sensitive acoustic microphone 430 can be obtained. For example, the pressure sensor 200 is mounted on the printed board 431 and an electric signal line is provided. A cover 433 is provided on the printed circuit board 431 so as to cover the pressure sensor 200.
According to the embodiment, a highly sensitive acoustic microphone can be provided.

(Seventh embodiment)
The embodiment relates to a blood pressure sensor using the pressure sensor of each of the above embodiments.
FIG. 52A and FIG. 52B are schematic views illustrating the blood pressure sensor according to the sixth embodiment.
FIG. 52A is a schematic plan view illustrating the skin over a human arterial blood vessel. FIG. 52B is a cross-sectional view taken along line H1-H2 in FIG.

  In the embodiment, the pressure sensor 200 is applied as the blood pressure sensor 440. For the pressure sensor 200, any one of the pressure sensors described in relation to the above embodiments and modifications thereof are used.

Thereby, highly sensitive pressure detection is possible with a small size pressure sensor. By pressing the pressure sensor 200 against the skin 443 above the arterial blood vessel 441, the blood pressure sensor 440 can continuously measure blood pressure.
According to this embodiment, a highly sensitive blood pressure sensor can be provided.

(Eighth embodiment)
The embodiment relates to a touch panel using the pressure sensor of each of the above embodiments.
FIG. 53 is a schematic plan view illustrating the touch panel according to the seventh embodiment.
In the embodiment, the pressure sensor 200 is used as the touch panel 450. For the pressure sensor 200, any one of the pressure sensors described in relation to the above embodiments and modifications thereof are used. In the touch panel 450, the pressure sensor 200 is mounted on at least one of the inside of the display and the outside of the display.

  For example, the touch panel 450 includes a plurality of first wires 451, a plurality of second wires 452, a plurality of pressure sensors 200, and a control unit 453.

  In this example, the plurality of first wirings 451 are arranged along the Y-axis direction. Each of the plurality of first wirings 451 extends along the X-axis direction. The plurality of second wirings 452 are arranged along the X-axis direction. Each of the plurality of second wirings 452 extends along the Y-axis direction.

  Each of the plurality of pressure sensors 200 is provided at each intersection of the plurality of first wirings 451 and the plurality of second wirings 452. One of the pressure sensors 200 is one of detection elements 200e for detection. Here, the intersection includes a position where the first wiring 451 and the second wiring 452 intersect and a region around the position.

  One end 251 of each of the plurality of pressure sensors 200 is connected to each of the plurality of first wirings 451. The other end 252 of each of the plurality of pressure sensors 200 is connected to each of the plurality of second wirings 452.

The control unit 453 is connected to the plurality of first wirings 451 and the plurality of second wirings 452.
For example, the control unit 453 includes a first wiring circuit 453a connected to the plurality of first wirings 451, a second wiring circuit 453b connected to the plurality of second wirings 452, and a first wiring circuit 453a. And a control circuit 455 connected to the second wiring circuit 453b.

  The pressure sensor 200 is capable of pressure sensing with a small size and high sensitivity. Therefore, a high-definition touch panel can be realized.

  The pressure sensor according to each of the above embodiments can be applied to various pressure sensor devices such as an air pressure sensor or a tire air pressure sensor in addition to the above applications.

  According to the embodiment, a highly sensitive strain sensing element, pressure sensor, microphone, blood pressure sensor, and touch panel can be provided.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding a specific configuration of each element such as a strain sensing element, a pressure sensor, a microphone, a blood pressure sensor, a substrate included in a touch panel, a strain sensing element, a first magnetic layer, a second magnetic layer, an intermediate layer, and a bias layer As long as a person skilled in the art can carry out the present invention by appropriately selecting from the well-known ranges and obtain the same effect, it is included in the scope of the present invention.

  Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, all strain detection elements, pressure sensors, and microphones that can be appropriately modified and implemented by those skilled in the art based on the strain detection elements, pressure sensors, microphones, blood pressure sensors, and touch panels described above as embodiments of the present invention. The blood pressure sensor and the touch panel also belong to the scope of the present invention as long as they include the gist of the present invention.

  In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... 1st magnetic layer (lower magnetic layer), 10m ... Magnetization, 10mf ... Initial magnetization, 10p, 10pb ... Bias, 10ph ... Magnetic field bias, 11 ... 1st magnetization fixed layer, 11m ... Magnetization, 12 ... 2nd magnetization fixed Layer, 12m ... magnetization, 13 ... magnetic coupling layer, 20 ... second magnetic layer (upper magnetic layer), 20m ... magnetization, 20mf ... initial magnetization, 20p, 20pb ... bias, 20ph ... magnetic field bias, 30 ... intermediate layer, 40 40a, 40b, 40c, 40d, 40e ... bias layer, 41a ... first bias magnetic layer, 41am ... magnetization, 41b ... second bias magnetic layer, 41bm ... magnetization, 41c ... third bias magnetic layer, 41cm ... magnetization, 42 ... Bias pinning layer, 42a ... Lower bias pinning layer, 42b ... Upper bias pinning layer, 43 ... Separation layer, 43a ... Lower part Layer, 43b ... upper separation layer, 44a ... first magnetic coupling layer, 44b ... second magnetic coupling layer, 50 ... underlayer, 60 ... pinning layer, 70 ... cap layer, 81 ... insulating layer, 83 ... hard bias layer, 83m ... hard bias, 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h, 100i, 100j, 100k, 100l, 100m ... strain detecting element, 100gc ... center of gravity, 101,102,103,104 ... strain 110a, 110a, 110b ... lower bias layer, 111a ... lower first bias magnetic layer, 111am ... magnetization, 111b ... lower second bias magnetic layer, 111bm ... magnetization, 111c ... lower third bias magnetic layer, 111cm ... Magnetization, 114a ... Lower first magnetic coupling layer, 114b ... Lower second magnetic Composite layer, 120, 120a, 120b ... Upper bias layer, 121a ... Upper first bias magnetic layer, 121am ... Magnetization, 121b ... Upper second bias magnetic layer, 121bm ... Magnetization, 124a ... Upper first magnetic coupling layer, 125bm ... Magnetization, 181 ... first straight line, 182 ... second straight line, 200, 200a, 200b ... pressure sensor, 200e ... detecting element, 201 ... supporting part, 201a ... hollow part, 201h ... through hole, 210 ... substrate, 210r ... outer edge 210gc: center of gravity, 221 ... first wiring, 222 ... second wiring, 230 ... via contact, 241 ... substrate, 242 ... thin film, 251 ... one end, 252 ... other end, 300 ... strain detecting element, 300a, 300b ... strain Detecting element, 410 ... microphone, 420 ... portable information terminal, 421 ... display unit, 430 ... acoustic microphone 431 ... Printed circuit board, 433 ... Cover, 435 ... Acoustic hole, 439 ... Sound, 440 ... Blood pressure sensor, 441 ... Arterial blood vessel, 443 ... Skin, 450 ... Touch panel, 451 ... First wiring, 452 ... Second wiring, 453 ... Control unit 453a ... First wiring circuit 453b ... Second wiring circuit 455 ... Control circuit 512D ... Drain, 512G ... Gate, 512I ... Element isolation insulating layer, 512M ... Semiconductor layer, 512S ... Source, 514a ... interlayer insulating film, 514b ... interlayer insulating film, 514c, 514d, 514e ... connection pillar, 514f, 514g ... wiring part, 514h, 514i ... interlayer insulating film, 514j, 514k ... connection pillar, 514l ... sacrificial layer, 531 ... semiconductor Substrate, 532 ... transistor, 550f ... laminated film, 557 ... Wire, 558 ... Wiring, 561bf ... Insulating film, 561f ... Conductive layer, 561fa ... Connection pillar, 562f ... Conductive layer, 562fa, 562fb ... Connection pillar, 564 ... Film part, 565 ... Insulating layer, 565f ... Insulating film, 566 ... Insulating layer, 566f ... insulating film, 566o, 566p ... opening, 567 ... fixed part, 570 ... cavity, 615 ... antenna, 616 ... electrical wiring, 617 ... transmission circuit, 617a ... converter, 617b ... Manchester encoding part, 617c ... Switching unit, 617d ... Timing controller, 617e ... Data correction unit, 617f ... Synchronization unit, 617g ... Determination unit, 617h ... Voltage controlled oscillator, 617r ... Reception circuit, 618 ... Reception unit, 618a ... Storage unit, 618b ... Center Calculation unit, 618d ... electronic device, 630 ... semiconductor circuit unit, 6 40 ... Pressure sensor, 650 ... Detection part, 664 ... Film part, 667 ... Fixed part, 671 ... Base part, 801 ... Force, E1 ... First electrode, E2 ... Second electrode, _Hc ... Coercive force, _Hk ... Different Isotropic magnetic field, MA1 ... easy magnetization axis, MA2 ... hard magnetization axis, MF ... magnetic field, R ... electric resistance, ST0 ... unstrained state, STc ... compressed state, STt ... tensile state, cs ... compressive stress, t ... thickness , Ts ... tensile stress

Claims (8)

A deformable substrate;
A strain sensing element provided on the substrate;
With
The strain sensing element is
A first layer having a first magnetization;
A second layer having a second magnetization, the second magnetization changing in response to deformation of the substrate;
An intermediate layer provided between the first layer and the second layer;
A third layer having a third magnetization;
Including
The second layer is provided between the intermediate layer and the third layer;
An angle between the third magnetization and the first magnetization is 30 ° or more and 60 ° or less, or 120 ° or more and 150 ° or less.   The sensor according to claim 1, wherein the first magnetization is fixed. A fourth layer,
The third layer is located between the fourth layer and the second layer;
The fourth layer is
At least one first material selected from the group consisting of Ir-Mn, Pt-Mn, Pd-Pt-Mn and Ru-Rh-Mn, and
CoPt (ratio of Co is, 50at.% Least 85 at.% Or _{less), (Co x Pt 100-} x) 100-y Cr y (x is 50at.% Or more 85 at.% Or less, y is 0 atomic.% Or more 40 at. % Or less) and at least one second material of FePt (the ratio of Pt is 40 at.% Or more and 60 at.% Or less),
The sensor according to claim 1 or 2, comprising at least one of the following.   The sensor according to claim 1, wherein at least a part of at least one of the first layer and the second layer is amorphous.   The sensor according to claim 1, further comprising a support portion that supports the substrate.   A microphone comprising the sensor according to claim 5.   A blood pressure sensor comprising the sensor according to claim 5.   A touch panel comprising the sensor according to claim 5.

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