JP2018160685A - Sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor capable of improving sensitivity, and a microphone.SOLUTION: According to an embodiment, a sensor includes a detection element. The detection element includes a first magnetic layer, a second magnetic layer containing FeB(0<y≤0.3), and an intermediate layer provided between the first magnetic layer and the second magnetic layer.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a sensor.

  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. The sensitivity of resistance change according to strain depends on, for example, the material of the spin valve film. For example, in a strain sensing element used for a pressure sensor using a spin technique, an improvement in sensitivity is desired.

“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 capable of improving sensitivity.

According to an embodiment, the sensor includes a sensing element. The sensing element is provided between the first magnetic layer, the second magnetic layer containing Fe _1-y B _y (0 <y ≦ 0.3), and the first magnetic layer and the second magnetic layer. And an intermediate layer.

FIG. 1A to FIG. 1C 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. FIG. 3A to FIG. 3C are graphs showing examples of experimental results of the strain sensing element according to the embodiment. FIG. 4A to FIG. 4C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment. FIG. 5A to FIG. 5C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment. FIG. 6A to FIG. 6C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment. FIG. 7A to FIG. 7C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment. FIG. 8A to FIG. 8C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment. Fig.9 (a)-FIG.9 (d) are graphs showing the example of another experimental result of a strain sensing element. It is a graph which shows the example of the result of the strain sensor characteristic of the strain sensing element concerning an embodiment. FIG. 11A and FIG. 11B are schematic views showing another strain sensing element according to the first embodiment. 12A and 12B are schematic perspective views illustrating the pressure sensor according to the second embodiment. FIG. 13A to FIG. 13E are schematic cross-sectional views in order of the processes, illustrating the manufacturing direction of the pressure sensor according to the embodiment. FIG. 6 is a schematic plan view illustrating a microphone according to a third embodiment. It is a typical sectional view which illustrates an acoustic microphone concerning a 4th embodiment. FIG. 16A and FIG. 16B are schematic views illustrating the blood pressure sensor according to the fifth embodiment. FIG. 10 is a schematic plan view illustrating a touch panel according to a sixth 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.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1A to FIG. 1C are schematic views illustrating the strain sensing element according to the first embodiment.
FIG. 1A is a schematic perspective view of a strain sensing element. FIG. 1B is a schematic cross-sectional view of the strain sensing element. FIG. 1C is a schematic cross-sectional view illustrating a pressure sensor in which a strain sensing element is used. In FIG. 1B, the first electrode and the second electrode are omitted for convenience of explanation.

  As illustrated in FIG. 1A, the strain sensing element 100 according to the embodiment includes a first magnetic layer 10, a second magnetic layer 20, and an intermediate layer 30. In this example, the strain sensing element 100 further includes a nonmagnetic layer 40, a first electrode E1, and a second electrode E2. The nonmagnetic layer 40 is not necessarily provided.

  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.

  In this example, the second electrode E2 is provided separately from the first electrode E1 in the stacking direction. The first magnetic layer 10 is provided between the first electrode E1 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 nonmagnetic layer 40 is provided between the second magnetic layer 20 and the second electrode E2.

  The first magnetic layer 10 and the second magnetic layer 20 may be interchanged with each other with the intermediate layer 30 interposed therebetween. In that case, the nonmagnetic layer 40 is provided between the second magnetic layer 20 and the first electrode E1.

  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. In the example shown in FIGS. 1A and 1B, the first magnetic layer 10 is a magnetization fixed layer. For example, the first magnetic layer 10 has a synthetic pin structure or a single pin structure. In this example, the first magnetic layer 10 has a synthetic pin structure. As will be described later, the first magnetic layer 10 may be a magnetization free layer.

  In the example shown in FIGS. 1A and 1B, the first magnetic layer 10 includes a first magnetization fixed layer 11, a second magnetization fixed layer 12, and a magnetic coupling layer 13. The magnetic coupling layer 13 is provided between the first magnetization fixed layer 11 and the second magnetization fixed layer 12.

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.
When a single pin structure is used for the first magnetic layer 10, 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. For example, Ru is used as the magnetic coupling layer 13. 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 first magnetization fixed layer 12 and the first magnetization fixed layer 11. 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 magnetoresistance effect (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.
For example, an Fe—Co alloy may be used as the first magnetization fixed layer 11 in addition to the Co—Fe—B alloy.

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. By using a FeCo alloy material having a bcc structure, a Co alloy containing a cobalt composition of 50% or more, or a material (Ni alloy) having a Ni composition of 50% or more as the first magnetization fixed layer 11, for example, a larger MR The rate of change is 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.

  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.

A ferromagnetic material is used for the second magnetic layer 20.
In the embodiment, the second magnetic layer 20 includes Fe _1-y B _y (0 <y ≦ 0.3). The entire second magnetic layer 20 may be formed of Fe _1-y B _y (0 <y ≦ 0.3). For example, Fe _1-y B _y (0 <y ≦ 0.3) is provided in a region of the second magnetic layer 20 that includes the boundary surface 20 s between the second magnetic layer 20 and the intermediate layer 30.

The second magnetic layer 20 is made of a material in which a part of Fe in Fe _1−y B _y (0 <y ≦ 0.3) is replaced by Co or Ni, that is, (Fe _a X _1−a ) _{1 -Y} B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) may be included. In the above-described (Fe _a X _1-a ) _1-y B _y , X is Co or Ni. That is, the second magnetic layer 20 has (Fe _a Co _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) or (Fe _a Ni _1-a ) _{1− y} B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) may be included.

The entire second magnetic layer 20 may be formed of (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). That is, the entire second magnetic layer 20 may be formed of (Fe _a Co _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). Alternatively, the entire second magnetic layer 20 may be formed of (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). For example, (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) is provided in a region including the boundary surface 20s.

The second magnetic layer 20 includes Fe _1-y B _y (0 <y ≦ 0.3) and (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0). .3) may be included. When X is Co, (Fe _a Co _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) is provided in a region including the boundary surface 20s. Is more preferable.

The second magnetic layer 20 may contain Co ₄₀ Fe ₄₀ B ₂₀ . In this case, Co ₄₀ Fe ₄₀ B ₂₀ is provided in a region including the boundary surface 20s.
For example, the second magnetic layer 20 includes both Fe _1-y B _y (0 <y ≦ 0.3) and Co ₄₀ Fe ₄₀ B ₂₀ . Co ₄₀ Fe ₄₀ B ₂₀ is provided in a region including the boundary surface 20s. Alternatively, for example, the second magnetic layer 20 includes both (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) and Co ₄₀ Fe ₄₀ B ₂₀ . including. Co ₄₀ Fe ₄₀ B ₂₀ is provided in a region including the boundary surface 20s.

The second magnetic layer 20 includes an amorphous part. For example, Fe _1-y B _y (0 <y ≦ 0.3) includes an amorphous state. For example, (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) includes an amorphous state.
The second magnetic layer 20 may include an amorphous part and a crystal part. For example, a region including the boundary surface 20s includes a crystalline state, and a region not including the boundary surface 20s includes an amorphous state.

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. As this insulator or semiconductor, for example, magnesium oxide (Mg—O or the like), aluminum oxide (Al ₂ O ₃ or the like), titanium oxide (Ti—O or the like), zinc oxide (Zn—O or the like) Alternatively, 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 1.5 nm thick MgO layer is used as the intermediate layer 30.

  For the nonmagnetic layer 40, for example, at least one of oxide, nitride, and oxynitride is used. The nonmagnetic layer 40 includes, for example, magnesium (Mg), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mg), iron (Fe), cobalt ( Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver ( Ag), hafnium (Hf), tantalum (Ta), tungsten (W), tin (Sn), cadmium (Cd) and at least one oxide selected from gallium (Ga), and It includes at least one of at least one nitride selected from the first group.

  The nonmagnetic layer 40 may include, for example, at least one oxide selected from the second group consisting of magnesium, titanium, vanadium, zinc, tin, cadmium, and gallium. For the nonmagnetic layer 40, for example, magnesium oxide, which is easy to obtain low resistance, is used.

  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 100. 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.

  By applying a voltage between the first electrode E <b> 1 and the second electrode E <b> 2, a current can be passed through the stacked body including the first magnetic layer 10, the intermediate layer 30, and the second magnetic layer 20. The current is, for example, along the Z-axis direction between the first magnetic layer 10 and the second magnetic layer 20.

  A pinning layer (not shown) may be provided between the first electrode E and the first magnetic layer 10. The pinning layer, for example, imparts unidirectional anisotropy to the first magnetic layer 10 (ferromagnetic layer) formed on the pinning layer to fix the magnetization of the first magnetic layer 10. . For the pinning layer, for example, an antiferromagnetic layer is used. For the pinning layer, for example, at least one selected from the group consisting of IrMn, PtMn, PdPtMn, and RuRhMn is used. The thickness of the pinning layer is appropriately set in order to impart sufficient unidirectional anisotropy.

  As shown in FIG. 1C, 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 strain sensing element 100 is provided on a part of the substrate 210.

  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.

  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.

  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 the change in magnetization will be described with respect to an example in which the resistance decreases when the relative angle of the magnetization of is small.

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, the nonmagnetic layer 40, The first electrode E1 and the second electrode E2 are omitted. In this example, the second magnetic layer 20 is a magnetization free layer, and the first magnetic layer 10 is a magnetization fixed layer.

  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 direction of magnetization of the magnetic layer in the initial state is set by, for example, an external magnetic field, 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.

  Here, as described above, the change in the electrical resistance in the strain sensing element 100 is caused by the magnetization 20 m of the second magnetic layer 20 (magnetization free layer) and the first magnetic layer 10 ( For example, it is detected as a resistance change corresponding to a relative angle between the magnetization 10 m of the magnetization fixed layer). Therefore, increasing the change in magnetization due to strain and increasing the resistance change depending on the difference in relative angle between the magnetization of the first magnetic layer 10 and the magnetization of the second magnetic layer 20 are highly sensitive. Required for realization of a strain sensor.

In order to make the magnetization of the magnetization free layer easy to move, it is desirable that the magnetization free layer has a soft magnetic characteristic without strong anisotropy. In order to make the magnetization of the magnetization free layer easy to move, it is desirable that the magnetization free layer includes a structure having no magnetocrystalline anisotropy.
On the other hand, in order to exhibit a high magnetoresistive effect above a certain level, it is desirable that the magnetization free layer has a certain crystal structure.
Such a trade-off in characteristics may hinder the improvement in sensitivity of the strain sensing element 100 and the pressure sensor 200.

  The sensitivity of the strain sensing element 100 depends on, for example, the materials of the first magnetic layer 10 and the second magnetic layer 20. For this reason, a magnetic material that produces a larger resistance change even with a slight strain is required. However, while there are relatively many magnetic materials that exhibit excellent properties in terms of magnetostriction, soft magnetic properties, and magnetoresistive effects, there is little knowledge of magnetic materials that exhibit excellent properties in terms of magnetostriction, soft magnetic properties, and magnetoresistive effects. It is not done. Therefore, it may be difficult to improve the sensitivity of the strain sensing element.

On the other hand, in the strain sensing element 100 according to the embodiment, the second magnetic layer 20 includes Fe _1-y B _y (0 <y ≦ 0.3). Alternatively, the second magnetic layer 20 includes (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). Alternatively, the second magnetic layer 20 includes Fe _1-y B _y (0 <y ≦ 0.3) and (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). In (Fe _a X _1-a ) _1-y B _y , X is Co or Ni.

  According to this, magnetostriction, soft magnetic characteristics, and magnetoresistance effect can be arranged side by side, and the sensitivity of the strain sensing element 100 can be improved. Details of this will be described later.

  The amorphous state ideally has no magnetocrystalline anisotropy and exhibits excellent soft magnetic properties. It is known that Fe-based amorphous exhibits a relatively large magnetostriction. On the other hand, in order to show a magnetoresistive effect, crystallinity is calculated | required in the interface 20s between the 2nd magnetic layer 20 and the intermediate | middle layer 30. FIG. When the region including the boundary surface 20s in the second magnetic layer 20 has crystallinity, a higher magnetoresistance effect can be obtained.

Therefore, when the region including the boundary surface 20s in the second magnetic layer 20 has crystallinity, and the region not including the boundary surface 20s in the second magnetic layer 20 is in an amorphous state, magnetostriction, Soft magnetic properties and magnetoresistance effects can be combined. The second magnetic layer 20 has Fe _1−y B _y (0 <y ≦ 0.3) and (Fe _a X _1−a ) _1−y B _y (0.8 ≦ a <1, 0 <y ≦ 0. 3) in the case where X is Co, (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) is When provided in a region including the boundary surface 20s, soft magnetic characteristics and magnetostriction can be arranged side by side while exhibiting a certain magnetoresistance effect. According to this, the sensitivity of the strain sensing element 100 can be further improved.

  Information regarding the distribution of the boron (B) concentration in the second magnetic layer 20 is obtained by secondary ion mass spectrometry. This information is obtained by the combination of the cross-section TEM and EDX. This information is obtained by EELS analysis. This information can also be obtained by three-dimensional atom probe analysis.

In the strain sensing element 100 according to the embodiment, the second magnetic layer 20 is provided between the intermediate layer 30 and the nonmagnetic layer 40. The material used for the nonmagnetic layer 40 is, for example, as described above. According to this, diffusion of boron (B) is suppressed, and the boron concentration in the second magnetic layer 20 is maintained. Therefore, deterioration of the characteristics of the second magnetic layer 20 can be suppressed. For example, the strain detecting elements 100, it is possible to obtain a smaller coercive force H _c, and a higher gauge factor by magnetization change by larger magnetostriction, the.

Next, an example of an experimental result of the strain sensing element 100 according to the embodiment will be described with reference to the drawings.
FIG. 3A to FIG. 3C are graphs showing examples of experimental results of the strain sensing element according to the embodiment.
Figure 3 (a) ~ FIG. 3 the second magnetic layer 20 of the strain detecting elements 100 in the example of the experimental results of (c) _{includes Fe 1-y B} y. The example of the experimental result regarding the atomic weight ratio y of boron (B) at this time is as having represented to Fig.3 (a)-FIG.3 (c).

FIG. 3A shows an example of the relationship between the MR ratio and the atomic weight ratio y of boron in the strain sensing element according to the embodiment. FIG. 3B shows an example of the relationship between the coercive force _Hc and the atomic weight ratio y of boron in the strain sensing element according to the embodiment. FIG. 3C shows an example of the relationship between the gauge factor B (GFB) and the atomic weight ratio y of boron.

  The inventor evaluates the strain sensing element 100 according to the embodiment using an index called a gauge factor B (GFB). GFB is expressed as a multiplier of the rate of change of magnetization due to MR and strain, and is proportional to the gauge factor (GF). That is, if the GFB is relatively large, a relatively high GF can be obtained. If the GFB is relatively small, a relatively low GF is obtained. As described above with reference to FIGS. 2A to 2C, a strain sensor with high sensitivity can be obtained by using a strain sensing element having a high gauge factor. In order to obtain a highly sensitive strain sensor, a higher GF (larger GFB) is desired.

The coercive force _Hc is a characteristic index indicating the ease of magnetization rotation. In order to obtain a highly sensitive strain sensor, a smaller coercive force _Hc is desired.
As described above with reference to FIGS. 1A to 1C, the MR effect is an effect obtained by reading a change in the relative angle of the magnetization direction as a change in electrical resistance. In order to obtain a highly sensitive strain sensor, that is, to increase the resistance change depending on the relative angle difference between the magnetization of the first magnetic layer 10 and the magnetization of the second magnetic layer 20, a higher MR change Rate is desired.

As shown in FIG. 3A, it can be seen that when the atomic weight ratio y of boron is larger than 0.3, the MR becomes relatively small. As shown in FIG. 3B, it can be seen that when the atomic weight ratio y of boron is 0.3, a relatively small coercive force _Hc is obtained. As shown in FIG. 3C, it can be seen that when the atomic weight ratio y of boron is 0.3, the magnetization change due to strain is sufficiently generated, and a GFB of 4000 or more can be obtained. Thereby, the atomic weight ratio y of boron in the second magnetic layer 20 is preferably 0.3 or less.

  On the other hand, as shown in FIG. 3A, when the second magnetic layer 20 does not contain boron (when y = 0), it can be seen that the MR is relatively small. As shown in FIG. 3B, it can be seen that the coercive force Hc is relatively large when the second magnetic layer 20 does not contain boron (when y = 0). As shown in FIG. 3C, when the second magnetic layer 20 does not contain boron (when y = 0), there is almost no change in magnetization due to strain, and the GFB is about 0. . Thereby, it is preferable that the atomic weight ratio y of boron of the second magnetic layer 20 is larger than zero.

  As shown in FIGS. 3A to 3C, the atomic weight ratio y of boron in the second magnetic layer 20 is preferably larger than 0 and not larger than 0.3. As shown in FIGS. 3A to 3C, the atomic weight ratio y of boron in the second magnetic layer 20 is more preferably 0.1 or more and 0.3 or less.

FIG. 4A to FIG. 4C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment.
Figure 4 (a) ~ 4 second magnetic layer 20 of the strain detecting elements 100 in the example of the experimental results of (c) _{comprises (Fe a Co 1-a)} 1-y B y. Examples of the experimental results regarding the atomic weight ratio a of iron (Fe) at this time, in other words, the atomic weight ratio 1-a of cobalt (Co) at this time are as shown in FIGS. 4 (a) to 4 (c). It is.

FIG. 4A shows an example of the relationship between the MR change rate and the atomic weight ratio a of iron in the strain sensing element according to the embodiment. FIG. 4B shows an example of the relationship between the coercive force _Hc and the atomic weight ratio a of iron in the strain sensing element according to the embodiment. FIG. 4C shows an example of the relationship between the gauge factor B (GFB) and the atomic weight ratio a of iron.
In the present study, the atomic weight ratio y of boron is 0.1 ≦ y <0.3.

As shown in FIG. 4C, it can be seen that 4000 or more GFB is obtained when the atomic weight ratio a of iron is about 0.8 or more. In other words, it can be understood that 4000 or more GFB is obtained when the atomic weight ratio 1-a of cobalt is about 0.2 or less. At this time, it can be seen that a relatively large MR can be obtained as shown in FIG. As shown in FIG. 4 (b), it can be seen that a relatively small coercive force H _c is obtained. Thereby, the atomic weight ratio a of iron of the second magnetic layer 20 is preferably 0.8 or more. In other words, the cobalt atomic weight ratio 1-a of the second magnetic layer 20 is preferably 0.2 or less.

FIG. 5A to FIG. 5C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment.
The second magnetic layer 20 of the strain sensing element 100 in the example of the experimental results of FIGS. 5A to 5C includes (Fe _a Ni _1-a ) _1-y B _y . Examples of the experimental results regarding the atomic weight ratio a of iron (Fe) at this time, in other words, the atomic weight ratio 1-a of nickel (Ni) at this time are as shown in FIGS. 5 (a) to 5 (c). It is.

FIG. 5A shows an example of the relationship between the MR change rate and the atomic weight ratio a of iron in the strain sensing element according to the embodiment. FIG. 5B illustrates an example of a relationship between the coercive force _Hc and the atomic weight ratio a of iron in the strain sensing element according to the embodiment. FIG. 4C shows an example of the relationship between the gauge factor B (GFB) and the atomic weight ratio a of iron.
In the present study, the atomic weight ratio y of boron is 0.1 ≦ y <0.3.

As shown in FIG. 5C, it can be seen that 4000 or more GFB is obtained when the atomic weight ratio a of iron is about 0.8 or more. In other words, it is understood that 4000 or more GFB is obtained when the atomic weight ratio 1-a of nickel is about 0.2 or less. At this time, it can be seen that a relatively large MR can be obtained as shown in FIG. As shown in FIG. 5 (b), it can be seen that a relatively small coercive force H _c is obtained. Thereby, the atomic weight ratio a of iron of the second magnetic layer 20 is preferably 0.8 or more. In other words, the nickel atomic weight ratio 1-a of the second magnetic layer 20 is preferably 0.2 or less.

FIG. 6A to FIG. 6C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment.
FIG 6 (a) ~ 6 second magnetic layer 20 of the strain detecting elements 100 in the example of the experimental results of (c) _{includes Fe 1-y B} y. Examples of _{Fe 1-y B} Experiment on the thickness t _y result at this time is as shown in FIG. 6 (a) ~ FIG 6 (c).

6 (a) is in the strain detecting element according to the embodiment represents an example of the relationship between the thickness t of the MR ratio and the _{Fe 1-y B} y. 6 (b) is in the strain detecting element according to the embodiment represents an example of the relationship between the thickness t of the coercive force _{H c} and _{Fe 1-y B} y. FIG. 6 (c) represents an example of the relationship between the gauge factor B (GFB) and the thickness t of _{Fe 1-y B} y.

As shown in FIG. 6A, it can be seen that a relatively large MR is obtained when the thickness t of Fe _1-y B _y is 2 nanometers (nm) or more. When the thickness t of Fe _1-y B _y is smaller than 2 nm, MR decreases. As a result, sufficient magnetic properties may not be obtained. As shown in FIG. 6B, it can be seen that a relatively small coercive force _Hc is obtained when the thickness t of Fe _1-y B _y is 2 nm or more. As shown in FIG. 6C, it can be seen that when the thickness t of Fe _1-y B _y is 2 nm or more, GFB of 4000 or more can be obtained. Thereby, the thickness t of Fe _1-y B _y is preferably 2 nm or more.

If Fe _1-y B _y having a thickness of t is 2nm or more, a region including a boundary surface 20s of the second magnetic layer 20 is maintained to have a crystallinity, of the second magnetic layer 20 It can be maintained that the region not including the boundary surface 20s is in an amorphous state.

On the other hand, as shown in FIG. 6C, it can be seen that when the thickness t of Fe _1-y B _y is greater than 12 nm, the GFB is smaller than 4000, which is a relatively small value. Thereby, the thickness t of Fe _1-y B _y is more preferably 12 nm or less.

As shown in FIG. 6 (a) ~ FIG 6 _(c), the thickness t of _{Fe 1-y B} y is preferably 2nm or more. As shown in FIGS. 6A to 6C, the thickness t of Fe _1-y B _y is more preferably 2 nm or more and 12 nm or less.

FIG. 7A to FIG. 7C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment.
The second magnetic layer 20 of the strain sensing element 100 in the example of the experimental results of FIGS. 7A to 7C includes both Fe _{1- y By} and Co ₄₀ Fe ₄₀ B ₂₀ . Co ₄₀ Fe ₄₀ B ₂₀ is provided in a region including the boundary surface 20s. Examples of _{Fe 1-y B} Experiment on the thickness t _y result at this time is as shown in FIG. 7 (a) ~ FIG 7 (c). In this experiment, the thickness l of Co ₄₀ Fe ₂₀ B ₂₀ is set to 0 nm, 0.5 nm, and 1 nm, respectively.

7 (a) is in the strain detecting element according to the embodiment represents an example of the relationship between the thickness t of the MR ratio and the _{Fe 1-y B} y. FIG. 7 (b), the strain detecting element according to the embodiment represents an example of the relationship between the thickness t of the coercive force _{H c} and _{Fe 1-y B} y. FIG. 7 (c) represents an example of the relationship between the gauge factor B (GFB) and the thickness t of _{Fe 1-y B} y.

As shown in FIG. 7C, it can be seen that even when Co ₄₀ Fe ₄₀ B ₂₀ of several nm is provided on the boundary surface 20s, 4000 or more GFB can be obtained. This is because, as shown in FIG. 7A, a larger MR is obtained than in the case of FeB alone, and a relatively small coercive force Hc is obtained as shown in FIG. 7B. Than _this, if both _{Fe 1-y B} y and _Co 40 _Fe 40 _{B 20} is included in the 20 magnetic _layer, Co _{40 Fe} 40 _{B 20} is desirably provided in a region including a boundary surface 20s. By providing Co ₄₀ Fe ₄₀ B ₂₀ that is easily crystallized at the interface, MR can be increased, and a strain sensor that is sensitive to changes in the direction of spin can be realized.

FIG. 8A to FIG. 8C are graphs showing examples of other experimental results of the strain sensing element according to the embodiment.
8A to 8C, the second magnetic layer 20 of the strain sensing element 100 has (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1). , 0 <y ≦ 0.3) and Co ₄₀ Fe ₄₀ B ₂₀ . Co ₄₀ Fe ₄₀ B ₂₀ is provided in a region including the boundary surface 20s. Examples of the experimental results regarding the thickness t of (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) at this time are shown in FIGS. This is as shown in FIG. In this experiment, the thickness l of Co ₄₀ Fe ₂₀ B ₂₀ is set to 0 nm, 0.5 nm, and 1 nm, respectively.

FIG. 8A shows an MR change rate and (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) in the strain sensing element according to the embodiment. Represents an example of the relationship with the thickness t. FIG. 8B shows the coercive force H _c and (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3) in the strain sensing element according to the embodiment. ) Represents an example of the relationship with the thickness t. FIG. 8C shows the gauge factor B (GFB) and the thickness t of (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). Represents an example relationship.

As shown in FIG. 8C, even when Co ₄₀ Fe ₄₀ B ₂₀ of several nm is provided on the boundary surface 20s, 4000 or more GFB is obtained, and (Fe _a Ni _1-a ) _1-y B It can be seen that it is possible to exceed the _y- only configuration. This is because, as shown in FIG. 8A, a larger MR is obtained than in the case of (Fe _a Ni _1-a ) _1-y B _y alone, and as shown in FIG. A small coercive force Hc can be maintained. In other words, it is because it is possible to purchase a small increment of the coercive force Hc with an increase in MR. For longer, contained in _{(Fe a Ni 1-a)} 1-y B y and _Co 40 _Fe 40 both _{B 20} and the second magnetic layer _20, Co _{40 Fe 40 B} 20, a region including a boundary surface 20s It is desirable to be provided. By providing Co ₄₀ Fe ₄₀ B ₂₀ that is easily crystallized at the interface, MR can be increased, and a strain sensor that is sensitive to changes in the direction of spin can be realized.

Fig.9 (a)-FIG.9 (d) are graphs showing the example of another experimental result of a strain sensing element.
FIG. 9A and FIG. 9B are graphs showing examples of other experimental results of the strain sensing element according to the embodiment.
FIG. 9C and FIG. 9D are graphs showing examples of other experimental results of the strain sensing element according to the comparative example.

The vertical axis in FIGS. 9A and 9C represents the magnetic film thickness (the product of the saturation magnetization Bs and the thickness t (Bs · t)). The horizontal axis of Fig.9 (a) and FIG.9 (c) represents a magnetic field. That is, FIG. 9A and FIG. 9C represent so-called BH curves (BH loops).
The vertical axis in FIGS. 9B and 9D represents a constant magnetic field (in this example, 0 magnetic field). The horizontal axis in FIG. 9B and FIG. 9D represents strain.

The second magnetic layer 20 of the strain sensing element 100 according to the embodiment in the example of the experimental results of FIGS. 9A and 9B includes Fe _1-y B _y .
The second magnetic layer 20 of the strain sensing element according to the comparative example in the experimental result examples of FIGS. 9C and 9C includes Co ₄₀ Fe ₄₀ B ₂₀ .

And graph of FIG. 9 (a), the graph of FIG. 9 (c), when comparing the second magnetic layer 20 is in the case of containing a _{Fe 1-y B y, B} -H when strain is applied Changes significantly. Accordingly, when the graph of FIG. 9B and the graph of FIG. 9D are compared, when the second magnetic layer 20 includes Fe _1-y B _y , B in a constant magnetic field is It can be greatly changed by strain. Therefore, according to the magnetic material (Fe _1-y B material containing _y), under conditions including a constant amount of boron, it is possible to realize a strain sensor with high sensitivity.
Note that the GFB of Co ₄₀ Fe ₄₀ B ₂₀ of the strain sensing element according to the comparative example is about 1500.

FIG. 10A to FIG. 10D are graphs showing examples of results of strain sensor characteristics of the strain sensing element of the embodiment.
In the example shown in FIG. 10A, for the strain sensing element 100 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 (% 0) or less. In between, it is set as a fixed value in steps of 0.2 (% 0). FIG. 10A shows an example of the result of measuring the magnetic field dependence of electrical resistance at each strain. 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 magnetization free layer is changed by the inverse magnetostriction effect.

  10 (b) to 10 (d) show that the external magnetic field of the strain sensing element 100 is fixed and the strain is continuously between −0.8 (% 0) and 0.8 (% 0). It shows the change in electrical resistance when sweeping. 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, the evaluation is performed by applying an external magnetic field of 5 Oe. In FIG. 10C, the evaluation is performed by applying an external magnetic field of 2 Oe. In FIG. 10D, the evaluation is performed at 0 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 be applied by providing a hard bias on the side wall of the strain sensing element or by providing an in-stack bias on the upper part of the magnetization free layer. In the strain sensing element 100 of the embodiment, an external magnetic field is simply applied by a coil for evaluation. 10 (b) to 10 (d), the gauge factor 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

From FIG. 10B, the gauge factor when the external magnetic field is 5 Oe is 3086. From FIG. 10C, the gauge factor when the external magnetic field is 2 Oe is 4418. From FIG. 10D, the gauge factor when the external magnetic field is 0 Oe is 5290. From this result, the maximum gauge factor (5290) is obtained when the bias magnetic field is 0 Oe.

FIG. 11A and FIG. 11B are schematic views illustrating another strain sensing element according to the first embodiment.
FIG. 11A is a schematic perspective view of a strain sensing element. FIG. 11B is a schematic cross-sectional view of the strain sensing element. In FIG. 11B, the first electrode and the second electrode are omitted for convenience of explanation.

  As illustrated in FIG. 11A, the strain sensing element 100 a according to the embodiment includes a first magnetic layer 10, a second magnetic layer 20, and an intermediate layer 30. In this example, the strain sensing element 100a further includes a first nonmagnetic layer 51, a second nonmagnetic layer 52, a first electrode E1, and a second electrode E2. The first nonmagnetic layer 51 and the second nonmagnetic layer 52 are not necessarily provided.

In the strain sensing element 100 described above with reference to FIGS. 1A and 1B, the first magnetic layer 10 is a magnetization fixed layer.
In contrast, in the strain sensing element 100a illustrated in FIGS. 11A and 11B, the first magnetic layer 10 is a magnetization free layer.

  In this example, the second electrode E2 is provided separately from the first electrode E1 in the stacking direction. A first nonmagnetic layer 51 is provided between the first electrode E1 and the second electrode E2. The first magnetic layer 10 is provided between the first nonmagnetic layer 51 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 second nonmagnetic layer 52 is provided between the second magnetic layer 20 and the second electrode E2.

In the strain sensing element 100a shown in FIGS. 11A and 11B, the first magnetic layer 10 is made of a ferromagnetic material. The first magnetic layer 10 includes the same material as the second magnetic layer 20 described above with reference to FIGS. 1 (a) and 1 (b).
That is, in this example, the first magnetic layer 10 includes Fe _1-y B _y (0 <y ≦ 0.3). Alternatively, the first magnetic layer 10 includes (Fe _a X _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). Alternatively, the first magnetic layer 10 includes Fe _1−y B _y (0 <y ≦ 0.3) and (Fe _a X _1−a ) _1−y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3). In (Fe _a X _1-a ) _1-y B _y , X is Co or Ni.

The first nonmagnetic layer 51 includes the same material as the nonmagnetic layer 40 described above with reference to FIGS. 1 (a) and 1 (b). The second nonmagnetic layer 52 includes the same material as the nonmagnetic layer 40 described above with reference to FIGS. 1A and 1B.
The second magnetic layer 20 is as described above with reference to FIGS. 1 (a) and 1 (b). The intermediate layer 30 is as described above with reference to FIGS. 1 (a) and 1 (b). The first electrode E1 is as described above with reference to FIGS. 1 (a) and 1 (b). The electrode E2 in FIG. 2 is as described above with reference to FIGS. 1 (a) and 1 (b).

Also in the strain sensing element 100a according to the embodiment, similarly to the strain sensing element 100 according to the embodiment, magnetostriction, soft magnetic characteristics, and magnetoresistance effect can be arranged side by side, and the sensitivity of the strain sensing element 100a can be improved.
Note that the magnetization pinned layer and pinning (not shown) described above with reference to FIG. 1 are provided at least between the first nonmagnetic layer 51 and the first electrode E1 and between the second nonmagnetic layer 52 and the second electrode E2. A layer may be provided.
(Second Embodiment)
The embodiment relates to a pressure sensor. In the pressure sensor, at least one of the strain sensing elements 100 and 100a of the first embodiment and the deformation strain sensing element thereof are used. Hereinafter, a case where the strain sensing element 100 is used as the strain sensing element will be described.

12A and 12B are schematic perspective views illustrating the pressure sensor according to the second embodiment.
FIG. 12A is a schematic perspective view. FIG. 12B is a cross-sectional view taken along line A1-A2 of FIG.
As illustrated in FIG. 12A and FIG. 12B, the pressure sensor 200 according to the embodiment includes a substrate 210 and a strain sensing element 100.

  As illustrated in FIGS. 12A and 12B, the pressure sensor 200 according to the embodiment includes a support unit 201, a substrate 210, and a strain sensing element 100.

  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. 12, 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.

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. 13A to FIG. 13E 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. 13A, 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. 13B, 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. 13C, 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. In the case where the sidewall of the laminate of the strain sensing element 100 is embedded with an insulating layer, a lift-off process may be applied. In the lift-off process, for example, after processing the laminated body, before peeling off the resist, an insulating layer is formed over the entire surface, and then the resist is removed.

  As shown in FIG. 13D, 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. 13E, 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.

(Third embodiment)
FIG. 14 is a schematic plan view illustrating a microphone according to the third embodiment.
As illustrated in FIG. 14, 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.

(Fourth embodiment)
The embodiment relates to an acoustic microphone using the pressure sensor of each of the above embodiments.
FIG. 15 is a schematic cross-sectional view illustrating an acoustic microphone according to the fourth 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.

(Fifth embodiment)
The embodiment relates to a blood pressure sensor using the pressure sensor of each of the above embodiments.
FIG. 16A and FIG. 16B are schematic views illustrating the blood pressure sensor according to the fifth embodiment.
FIG. 16A is a schematic plan view illustrating the skin over a human arterial blood vessel. FIG. 16B is a cross-sectional view taken along the line H1-H2 of 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.

(Sixth embodiment)
The embodiment relates to a touch panel using the pressure sensor of each of the above embodiments.
FIG. 17 is a schematic plan view illustrating the touch panel according to the sixth 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 261 of each of the plurality of pressure sensors 200 is connected to each of the plurality of first wirings 451. The other end 262 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 the touch panel, a strain sensing element, a first magnetic layer, a second magnetic layer, an intermediate layer, and a nonmagnetic layer Are included in the scope of the present invention as long as those skilled in the art can implement the present invention in the same manner by appropriately selecting from the well-known ranges and obtain similar effects.

  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 designed 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, 10m ... Magnetization, 11 ... 1st magnetization fixed layer, 12 ... 2nd magnetization fixed layer, 13 ... Magnetic coupling layer, 20 ... 2nd magnetic layer, 20m ... Magnetization, 20s ... Interface, 30 DESCRIPTION OF SYMBOLS ... Intermediate layer, 40 ... Nonmagnetic layer, 51 ... 1st nonmagnetic layer, 52 ... 2nd nonmagnetic layer, 100, 100a ... Strain sensing element, 200 ... Pressure sensor, 200e ... Detection element, 201 ... Support part, 201a ... hollow portion, 201h ... through hole, 210 ... substrate, 210r ... outer edge, 221 ... first wiring, 222 ... second wiring, 241 ... base, 242 ... thin film, 261 ... one end, 262 ... other end, 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 4 DESCRIPTION OF SYMBOLS 1 ... Arterial blood vessel, 443 ... Skin, 450 ... Touch panel, 451 ... 1st wiring, 452 ... 2nd wiring, 453 ... Control part, 453a ... Circuit for 1st wiring, 453b ... Circuit for 2nd wiring, 455 ... Control circuit , 801 ... power, E1 ... first electrode, E2 ... second electrode, H c _... coercivity, R ... resistance, ST0 ... no strain state, STc ... compressed state, STt ... tension, a ... atomic weight ratio, cs ... compressive stress, t ... thickness, ts ... tensile stress, y ... atomic weight ratio

The magnetic coupling layer 13 generates antiferromagnetic coupling between the second magnetization fixed layer 12 and the first magnetization fixed layer 11. For example, Ru is used as the magnetic coupling layer 13. As long as the material cause sufficient antiferromagnetic coupling between the first magnetization pinned layer 1 1 and the second magnetization pinned layer 1 2, it may be a material other than Ru as the magnetic coupling layer 13. 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.

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. As this insulator or semiconductor, for example, magnesium oxide (Mg—O or the like), aluminum oxide (Al ₂ O ₃ or the like), titanium oxide (Ti—O or the like), zinc oxide (Zn—O or the like) Alternatively, 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 the CCP spacer layer is used as the intermediate layer 30 , for example, in an insulating layer of aluminum oxide (Al ₂ O ₃ ). A structure in which a copper (Cu) metal path is formed is used. For example, a 1.5 nm thick MgO layer is used as the intermediate layer 30.

For the nonmagnetic layer 40, for example, at least one of oxide, nitride, and oxynitride is used. The nonmagnetic layer 40 includes, for example, magnesium (Mg), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), manganese (M n ), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), hafnium (Hf), tantalum (Ta), tungsten (W), tin (Sn), at least one oxide selected from the first group consisting of cadmium (Cd) and gallium (Ga), and , At least one of at least one nitride selected from the first group.

FIG. 5A shows an example of the relationship between the MR change rate and the atomic weight ratio a of iron in the strain sensing element according to the embodiment. FIG. 5B illustrates an example of a relationship between the coercive force _Hc and the atomic weight ratio a of iron in the strain sensing element according to the embodiment. FIG. 5 (c) represents an example of the relationship between the gauge factor B and (GFB) and atomic weight ratio a of iron.
In the present study, the atomic weight ratio y of boron is 0.1 ≦ y <0.3.

The second magnetic layer 20 of the strain sensing element 100 according to the embodiment in the example of the experimental results of FIGS. 9A and 9B includes Fe _1-y B _y .
Figure 9 (c) and 9 strain detecting second magnetic layer 20 of the device according to the comparative example in the example of the experimental results of (d) _includes Co _{40 Fe 40 B 20.}

Claims (5)

A first magnetic layer;
A second magnetic layer containing Fe _1-y B _y (0 <y ≦ 0.3);
An intermediate layer provided between the first magnetic layer and the second magnetic layer;
A sensor having a sensing element including: A first magnetic layer;
A second magnetic layer comprising (Fe _a Ni _1-a ) _1-y B _y (0.8 ≦ a <1, 0 <y ≦ 0.3);
An intermediate layer provided between the first magnetic layer and the second magnetic layer;
A sensor having a sensing element including:   The sensor according to claim 1, wherein the detection element is provided on a deformable substrate. A printed circuit board,
A cover,
A support provided between the printed circuit board and the cover;
Further comprising
The sensor according to claim 3, wherein the substrate is supported by the support portion between the printed circuit board and the cover.   5. The sensor according to claim 1, wherein an electric resistance of the detection element changes according to a sound wave or an ultrasonic wave applied to the sensor.