JPH0875570A - Dynamic quantity sensor - Google Patents

Abstract

PURPOSE: To provide a dynamic quantity sensor wherein a thin film process is used, a sensor for minutely and planarly using a stress magnetic effect is formed, and miniaturization, integration and high sensitivity are contrived. CONSTITUTION: A ferromagnetic body layer 13 having magnetostriction, a ferromagnetic body layer 15 having a magnetic resistance effect, a magnetic field generation means 12, 14 for magnetizing these ferromagnetic body layers and a substrate 11 integrally supporting these are equipped. The change of a magnetic flux desity passing through the ferromagnetic body layer caused by the change of magnetic characteristic due to stress is detected at input and output terminals as the change of a resistance value caused by the magnetic resistance effect, so that a miniature and thin dynamic quantity sensor of high sensitivity capable of integration is formed. As the result, the miniature and thin dynamic quantity sensor, which utilizes the stress magnetic effect, of the high sensitivity can be made. In addition, strength of stress along a direction can be selectively detected on the basis of the anisotropy of detection sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical quantity sensor, and more particularly to a mechanical quantity sensor capable of detecting stress or strain with high sensitivity.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and thinner, there has been a demand for further miniaturization of mechanical quantity sensors used in electronic devices. As a mechanical sensor utilizing the stress-magnetic effect, an amorphous magnetic alloy ribbon with a positive saturation magnetostriction constant is bonded on a cylinder, and the change in magnetic permeability of the ribbon due to applied stress is detected by a solenoid coil. Sensors have been put to practical use (eg SAE TECHNICAL PAPERSERIES 920700).

Such a conventional mechanical quantity sensor has a coil made by winding a wire (diameter: 20 to 30 μm or more) in a solenoid shape, and a ferromagnetic bulk (thickness: 20 to 30).
μm) and.

[0004]

However, in the above-mentioned conventional mechanical quantity sensor, a coil manufactured by winding a wire rod in a solenoid shape and a ferromagnetic bulk are used, so that miniaturization and integration of the sensor are difficult. There is a problem.
Further, it is necessary to convert the inductance change of the coil into a voltage, and there is a problem that the amplifier circuit becomes complicated as compared with the case where the resistance change is converted into a voltage.

As a planar mechanical quantity sensor more suitable for miniaturization, there is a strain gauge using a metal foil, but the sensitivity is less than one thousandth as compared with the one using the stress magnetic effect.
An object of the present invention is to provide a small and thin mechanical sensor of high sensitivity that can be integrated, in order to solve the conventional problems.

[0006]

In order to achieve the above object, a mechanical quantity sensor of the present invention comprises a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, and these ferromagnetic layers. A magnetic field generating means for exciting the magnetic field and a substrate integrally supporting the magnetic field generating means are provided, and a change in magnetic flux density passing through the ferromagnetic layer due to a change in magnetic characteristics due to stress is changed as a change in resistance value by a magnetoresistive effect. It is characterized by detecting.

In the above structure, it is preferable that the direction of the magnetic field that excites the ferromagnetic layer is substantially parallel to the direction of stress. In the above structure, it is preferable that an electric insulating layer is further provided between the substrate and the ferromagnetic layer having magnetostriction.

In the above structure, it is preferable that an electric insulating layer is further provided between the ferromagnetic layer having magnetostriction and the ferromagnetic layer having a magnetoresistive effect. Further, in the above structure, it is preferable that the ferromagnetic layer having a magnetoresistive effect is connected to the power input / output terminal.

Further, in the above structure, between the ferromagnetic layer having magnetostriction and the ferromagnetic layer having a magnetoresistive effect, a nonmagnetic layer for magnetically separating these is provided, and these ferromagnetic layers are provided. Is preferably excited by a current flowing in a ferromagnetic layer having a magnetoresistive effect.

In the above structure, it is preferable that the ferromagnetic layer and the non-magnetic layer are formed by a vapor phase film forming method or a liquid phase film forming method. Further, in the above structure, a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, and a nonmagnetic conductive layer formed at a position sandwiched between these ferromagnetic layers are electrically connected to each other. It is preferable to provide a non-magnetic insulating layer for insulation, and to excite these ferromagnetic layers by a current flowing through the conductor layer.

Further, in the above structure, it is preferable that the nonmagnetic conductive layer is connected to a power input / output terminal different from the power input / output terminal connected to the ferromagnetic layer having a magnetoresistive effect.

Further, in the above structure, it is preferable that the ferromagnetic layer, the nonmagnetic conductor layer and the nonmagnetic insulating layer are formed by a vapor phase film forming method or a liquid phase film forming method. Further, in the above structure, there are two ferromagnetic layers having magnetostriction substantially parallel to each other when viewed from the cross-sectional direction, and the ferromagnetic layer and the ferromagnetic layer are substantially provided in a gap portion between the two ferromagnetic layers. A ferromagnetic material layer having a magnetoresistive effect arranged in parallel,
It is preferable that a magnet layer for exciting these ferromagnetic layers be provided outside both of the two ferromagnetic layers having magnetostriction.

In the above structure, it is preferable that the ferromagnetic layer and the magnet layer are formed by a vapor phase film forming method or a liquid phase film forming method. Further, in the above structure, the ferromagnetic layer having magnetostriction is preferably an amorphous magnetostrictive alloy.

In the above structure, the amorphous magnetostrictive alloy is Fe-Cr-Si-B type, Fe-Nb-Si type.
-B system, Fe-V-Si-B system, Fe-Co-Si-B
System, Fe-W-Si-B system, Fe-Ni-Cr-Si-
B system, Fe-Ni-Nb-B system and Fe-Ni-Mo-
It is preferably at least one selected from the B series.

In the above structure, the amorphous magnet is used.
Strain alloy is Fe₇₅Cr_FourSi_12.5B _8.5Like to be
Good Further, in the above structure, it has a magnetoresistance effect.
The ferromagnetic layer is preferably a NiFe alloy film.
Yes.

In the above structure, the electrical insulating layer is S.
It is preferably iO ₂ . Further, in the above structure, the substrate is preferably selected from metal, glass or ceramics.

[0017]

According to the structure of the present invention, a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, a magnetic field generating means for exciting these ferromagnetic layers, and these are integrally formed. A compact, thin, integrated device is provided that includes a supporting substrate and detects a change in magnetic flux density passing through the ferromagnetic layer due to a change in magnetic characteristics due to stress as a change in resistance value due to a magnetoresistive effect. It is possible to realize a highly sensitive mechanical quantity sensor capable of That is, it is possible to form a mechanical quantity sensor using the stress magnetic effect in a minute and planar shape by a thin film process, and it is possible to easily cope with miniaturization, integration, and high sensitivity.

According to the preferable example in which the direction of the magnetic field for exciting the ferromagnetic layer is substantially parallel to the stress direction, the magnetic anisotropy is induced in the stress direction. Change the permeability of the ferromagnetic layer with magnetic flux,
It can be detected with the highest sensitivity.

Further, in the above description, a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, and a non-magnetic layer for magnetically separating these are provided, and the excitation of these ferromagnetic layers is magnetoresistive. According to a preferred example of being performed by a current flowing in the ferromagnetic layer having an effect, since the ferromagnetic layer having a magnetoresistive effect serves as a magnetic field generating means,
The structure is simple. Further, since the generated magnetic force forms a small loop in the vicinity thereof, it is possible to efficiently detect the strain of a minute portion.

According to the preferable example in which the ferromagnetic layer and the non-magnetic layer are formed by the vapor phase film forming method or the liquid phase film forming method, the shape of the magnetic circuit can be accurately formed. It enables miniaturization and solidification. The vapor phase film forming method is preferably performed by a vacuum vapor deposition method or a sputtering method.
The film formation by the vacuum evaporation method is performed by evaporating the target substance by electron beam heating or resistance heating in a high vacuum of 10 ⁻⁵ Torr or more. The film formation by the sputtering method has a vacuum degree of 10 ^-2 to 1
This is performed by sputter-evaporating a target substance with ionized argon in an atmosphere containing 0 ^-5 Torr of argon as a main component. The liquid phase film forming method is preferably performed by plating.

Further, in the above description, a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, a non-magnetic conductor layer formed at a position surrounded by these ferromagnetic layers, and an electrically conductive layer formed of these layers. According to a preferable example in which a non-magnetic insulating layer for electrically insulating the ferromagnetic layers is provided, the excitation of the ferromagnetic layers is performed by the current flowing in the conductor layer. Can independently control the electric current, and the degree of freedom in designing the magnetic circuit and the electric circuit is increased. Further, since the generated magnetic flux forms a small loop in the vicinity thereof, it is possible to efficiently detect the distortion of a minute portion.

According to the preferable example in which the ferromagnetic layer, the non-magnetic conductor layer and the non-magnetic insulating layer are formed by a vapor phase film forming method or a liquid phase film forming method, the shape of the magnetic circuit is formed. Can be manufactured accurately, and miniaturization and solidification are possible.

Further, in the above description, a ferromagnetic layer having magnetostriction, and a ferromagnetic layer having a magnetoresistive effect, which is arranged in a gap portion of the ferromagnetic layer substantially in parallel with the ferromagnetic layer, According to the preferable example in which the ferromagnetic layers are composed of magnet layers for exciting the ferromagnetic layers, it is not necessary to supply a current for excitation, and power consumption can be reduced.

According to the preferable example in which the ferromagnetic layer and the magnet layer are formed by the vapor phase film formation method or the liquid phase film formation method, the shape of the magnetic circuit can be accurately formed, and It becomes possible to solidify and solidify.

According to the preferable example in which the magnetostrictive metal ribbon is an amorphous magnetostrictive alloy, the mechanical quantity can be accurately detected. In particular, amorphous magnetostrictive alloys are Fe-Cr-Si-B type, Fe-Nb-Si-B type.
System, Fe-V-Si-B system, Fe-Co-Si-B system,
Fe-W-Si-B system, Fe-Ni-Cr-Si-B
System, Fe-Ni-Nb-B system and Fe-Ni-Mo-B
It is preferably at least one selected from the systems.
Fe ₇₅ Cr ₄ Si _12.5 B _8.5 is particularly preferable. The composition of the amorphous magnetostrictive alloy ribbon is Fe ₇₅ Cr in atom%.
_In the case of ₄ Si _12.5 B _8.5 , the crystallization temperature was 460 ° C. and the saturation magnetostriction constant was 22 ppm.

According to the present invention, a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, a magnetic field generating means for exciting these ferromagnetic layers, and a substrate integrally supporting these layers. By detecting a change in magnetic flux density passing through the ferromagnetic layer due to a change in magnetic characteristics due to stress as a change in resistance value due to a magnetoresistive effect, the size is small and thin, and high integration is possible. A mechanical sensor with high sensitivity can be realized. As a result, it is possible to provide a small, thin, and highly sensitive mechanical quantity sensor that utilizes the stress magnetic effect. Further, the intensity of stress along a certain direction can be selectively detected based on the anisotropy of detection sensitivity.

[0027]

Embodiments of the present invention will be described below. In the following examples, the ferromagnetic layer having magnetostriction is abbreviated as a magnetostrictive layer, and the ferromagnetic layer having a magnetoresistive effect is abbreviated as a magnetoresistive element.

(Embodiment 1) FIG. 1 is a plan view showing the structure of a mechanical quantity sensor of this embodiment. FIG. 2 is a sectional view taken along line II of FIG. Hereinafter, the configuration of the mechanical quantity sensor of the present embodiment will be described with reference to these drawings.

Long side 10 mm, short side 5 mm, thickness 0.5 m
A magnetostrictive layer 13, which is a ferromagnetic layer having magnetostriction, has an area of 2 mm length × 2 mm width (area of 2 mm square) and a thickness of 1 μm is formed in the center of the substrate 11 of m. The material of the substrate 11 may be any material such as metal and ceramics as long as it is a non-magnetic material, and titanium is used in this embodiment. The substrate surface is covered with an insulating layer 12 of SiO _{2 having} a thickness of 0.3 μm. The shape of the substrate 11 is not limited to the flat plate shape shown in FIG. 2 or the rectangular shape existing on the back side of the insulating layer 12 of FIG. The magnetostrictive layer 13 in FIG. 2 is made of a Fe-based amorphous alloy film formed by a sputtering method and contains Fe, Cr, Si and B. Its composition is Fe ₇₅ Cr ₄ Si _12.5 B _8.5 . The relative permeability of the magnetostrictive layer 13 at 1 MHz is 100.
0, the saturation magnetostriction constant is +22 ppm.

An insulating layer (thickness: 0.2 μm) made of SiO ₂ formed by the sputtering method is formed on the magnetostrictive layer 13.
m) 14 is formed. The substrate 1 is provided on the insulating layer 14.
A linear magnetoresistive element 15 (width 50 μm, length 3 mm, thickness 0.1 μm) is formed in the short side direction of 1 and is connected to the input / output terminals 16a and 16b. The insulating layer 14 is a nonmagnetic material, and also serves to magnetically separate the magnetostrictive layer 13 and the magnetoresistive element 15. In addition, the magnetoresistive element 15
Is composed of a NiFe alloy film formed by a vapor deposition method. During vapor deposition, a magnetic field is applied in the longitudinal direction of the magnetoresistive element 15 to give uniaxial magnetic anisotropy with the longitudinal direction as the easy axis of magnetization. That is, the magnetoresistive element 15 has an anisotropic magnetoresistive effect.

Next, the operation of the mechanical quantity sensor according to this embodiment will be described. Of the in-plane directions of the substrate 11, the substrate longitudinal direction is S
The longitudinal direction of the magnetoresistive element 15 (the direction of the easy axis of magnetization of the magnetoresistive element 15) is the E direction. In addition, stress was applied so as to occur in the S direction on the substrate surface, and the characteristic change was measured.

When no magnetic field is applied, the magnetization Ms of the magnetoresistive element 15 is aligned in the easy magnetization axis direction (E direction). When a current is applied to the magnetoresistive element 15, a magnetic field is generated,
A magnetic flux 17 as shown in FIG. 2 passing through the magnetoresistive element 15 and the magnetostrictive layer 13 is generated in the S direction. As a result, Ms rotates in the S direction and makes an angle θ with the E direction. As is well known, in a magnetoresistive element having an anisotropic magnetoresistive effect, a resistance change occurs due to rotation of magnetization, and the resistance change can be expressed by the following formula (Equation 1). Here, R is a resistance value, R ₀ is a resistance value when θ is 0, and ΔR is called an anisotropic magnetic resistance and is a constant indicating a resistance change amount.

[0033]

[Equation 1]

As is clear from the above equation (Equation 1), the resistance value decreases as the magnetic field becomes stronger, and the resistance change saturates when Ms points in the S direction (θ = 90 °). The magnetic field at saturation is called an anisotropic magnetic field (Hk), and Hk of the magnetoresistive element of this embodiment is 480 A / M. The magnetoresistive element made of a ferromagnetic material has the advantage that it has a higher sensitivity in a low magnetic field than a semiconductor magnetoresistive element or a Hall element and can be excited in a low magnetic field. In this embodiment, with no stress applied,
The current is adjusted so that the resistance becomes approximately R ₀ -1 / 2ΔR, and the sensor operates in the intermediate state of the resistance change.

The operation when stress is applied will be described. When stress is applied to the substrate 11, S of the magnetostrictive layer 13 is applied.
Stress is generated in the direction. When stress is applied to the ferromagnetic layer having magnetostriction, magnetic anisotropy is induced in the stress direction by the magnetoelastic energy, and the magnetic permeability in the stress direction changes. Since the magnetic flux 17 and the direction of the stress coincide with each other, the magnetic flux density (magnetic field) of the magnetic flux 17 changes, and as a result, M _s rotates and the resistance value of the magnetoresistive element 15 changes. Since the magnetostrictive layer having a positive saturation magnetostriction constant is used in this embodiment, the magnetic permeability increases when the tensile stress is applied and decreases when the compressive stress is applied. Therefore, the resistance value of the magnetoresistive element 15 decreases when the tensile stress is applied and increases when the compressive stress is applied. The operating point when the stress is zero is brought to R ₀ −1 / 2ΔR in order to improve the linearity of the resistance change. Further, in this embodiment, the magnetoresistive element 15 is arranged so that the longitudinal direction of the magnetoresistive element having the anisotropic magnetoresistive effect (the direction of the easy axis of magnetization) is 90 ° with respect to the stress applying direction. This is because the direction of the generated magnetic flux and the direction of the stress are made to coincide with each other to maximize the sensitivity to the stress. When the direction of the magnetic flux is deviated from the direction of the stress, the magnetic flux density is changed by the magnetic flux direction component of the stress, and the obtained resistance change Δr is expressed by the following formula (Equation 2). Here, θ ′ is the angle formed by the magnetic flux direction and the stress direction, and Δr ₀ is the value of Δr when θ ′ is 0.

[0036]

[Equation 2]

From the above equation (Equation 2), when θ ′ = 90 °, the change due to stress becomes zero. Therefore, when temperature compensation is performed, a temperature-compensating magnetoresistive element may be formed in this direction.

Finally, the result of characteristic measurement will be described. When stress was applied to the surface of the substrate 11 so as to generate strain of −50 ppm to +50 ppm, a resistance change of 1.2% was obtained.

(Second Embodiment) FIG. 3 is a plan view showing the structure of a mechanical quantity sensor (second embodiment) according to the present invention. FIG.
FIG. 4 is a sectional view taken along line II-II in FIG. 3. Hereinafter, the mechanical quantity sensor of the present embodiment will be described with reference to these drawings.

The structure, material and manufacturing process of the mechanical quantity sensor of this embodiment are almost the same as those of the mechanical quantity sensor of the first embodiment. The difference is that the non-magnetic conductive wire 21 for exciting the magnetostrictive layer 13 and the magnetoresistive element 15 is arranged at a position sandwiched by the magnetostrictive layer 13 and the magnetoresistive element 15 via the insulating layers 14a and 14b. is there. The non-magnetic conductor 21 is the terminal 2
It is connected to 2a and 22b. The non-magnetic conducting wire 21 is made of an aluminum film formed by a sputtering method and has a thickness of 1
The μm and width are the same as those of the magnetoresistive element 15. With this configuration, the current for exciting the ferromagnetic layer and the current for sensing can be controlled independently, and the degree of freedom on the magnetic circuit or the electric circuit is increased. Further, since a current for excitation is passed through a conductor layer having a high conductivity and a large film thickness, a temperature change due to heat generation of the magnetoresistive element 15 is small.

The operation is similar to that of the first embodiment. When a current is passed through the non-magnetic conductor 21, a magnetic field is generated, and a magnetic flux 2 passing through the magnetoresistive element 15 and the magnetostrictive layer 13 in the S direction as shown in FIG.
3 occurs. When stress is applied in the S direction, the magnetic flux density of the magnetic flux 23 changes and the resistance value of the magnetoresistive element 15 changes. Also in the present embodiment, the non-magnetic conductor wire 21 forms 90 degrees with respect to the S direction in order to match the stress direction and the excitation direction.

The change in resistance value with respect to the stress was 1.2% when the stress was applied so that strain of −50 ppm to +50 ppm was generated on the surface of the substrate 11 as in Example 1. (Third Embodiment) FIG. 5 shows a mechanical quantity sensor (third embodiment) according to the present invention.
It is a top view which shows the structure of (Example). FIG. 6 shows II of FIG.
It is a sectional view taken along the line I-III. Hereinafter, the configuration of the mechanical quantity sensor of the present embodiment will be described with reference to these drawings.

Long side 10 mm, short side 5 mm, thickness 0.5 m
m in the central part on the glass substrate 31 in a straight line in the short side direction of the substrate 31 (width 50 μm, length 3 mm, thickness 0.1 μm)
The magnetoresistive element 32 is formed, and the input / output terminals 33a and 3a
It is connected to 3b. Then, the magnetoresistive element 32
An insulating layer 34 is formed so as to cover the. Insulating layer 34
A magnetostrictive layer 35 having a linear slit so as to partially overlap with the magnetoresistive element 32 is formed on the upper portion. The shapes, materials, and manufacturing processes of the magnetoresistive element 32 and the insulating layer 34 are the same as those in the first embodiment. The magnetostrictive layer 35 has the same thickness and the same manufacturing process. □ 2m on both sides of these
Magnet layers 36a and 36b having an area of m and a thickness of 2 μm are formed. The magnet layers 36a and 36b are magnets made of a CoPt alloy prepared by a sputtering method, and are magnetized so that the magnetization is oriented in the longitudinal direction of the substrate.

Next, the operation of the mechanical quantity sensor of this embodiment will be described. Of the in-plane directions of the substrate 31, the substrate longitudinal direction is the S direction, and the longitudinal direction of the magnetoresistive element 32 (the magnetoresistive element 32
The direction of the easy axis of magnetization is defined as E direction. In addition, stress was applied so as to occur in the S direction on the substrate surface, and the characteristic change was measured.

Since the magnet layers 36a and 36b are magnetized in the S direction, the magnetic flux 37 generated therefrom passes through the magnetostrictive layer 35 and the magnetoresistive element 32 along the S direction as shown in FIG. The magnet layers 36a and 36b have a resistance value R ₀ −1/2 of the magnetoresistive element 32 when no stress is applied.
The shape and arrangement are such that ΔR is achieved.

When stress is applied in the S direction, the magnetic flux density of the magnetic flux 37 changes and the resistance value of the magnetoresistive element 32 changes for the same reason as in the first embodiment. Also in this embodiment, it is designed so that the direction of excitation matches the direction of stress. The output when the stress and the excitation direction are deviated is the same as that in the first embodiment.

The change in resistance value with respect to the stress was 1.4% when the stress was applied so that strain of −50 ppm to +50 ppm was generated on the surface of the substrate 31. Above Examples 1-3
In the case of Fe, the magnetostrictive layer was formed by the sputtering method.
Although the base amorphous alloy is used, it goes without saying that a similar sensor can be constructed with other ferromagnetic layers having magnetostriction.

Although the NiFe alloy film having an anisotropic magnetoresistive effect prepared by the vapor deposition method was used as the magnetoresistive element in the above Examples 1 to 3, another ferromagnetic layer whose resistance value changes with a magnetic field is used. It is clear from the configuration of the magnetic circuit of the sensor of the present invention that a similar sensor can be constructed (for example, giant magnetoresistive effect; Journal of Japan Applied Magnetics 16, pp 614-635).

[0049]

As described above, according to the present invention, a ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, a magnetic field generating means for exciting these ferromagnetic layers, and these are provided. By providing a substrate that is integrally supported and detecting a change in magnetic flux density passing through the ferromagnetic layer due to a change in magnetic characteristics due to stress as a change in resistance value due to a magnetoresistive effect, a small and thin device can be obtained. A highly sensitive mechanical quantity sensor that can be integrated can be realized. That is, it is possible to form a mechanical quantity sensor using the stress magnetic effect in a minute and planar shape by a thin film process, and it is possible to easily cope with miniaturization, integration, and high sensitivity.

[Brief description of drawings]

FIG. 1A is a plan view of a mechanical quantity sensor according to a first embodiment of the present invention, and FIG. 1B is an explanatory view showing a detected magnetic direction of the sensor.

FIG. 2 is a sectional view taken along line I-I of FIG.

FIG. 3A is a plan view of a mechanical quantity sensor according to a second embodiment of the present invention, and FIG. 3B is an explanatory view showing a detected magnetic direction of the sensor.

4 is a sectional view taken along line II-II of FIG.

5A is a plan view of a mechanical quantity sensor according to a third embodiment of the present invention, and FIG. 5B is an explanatory view showing a detected magnetic direction of the sensor.

6 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

 11, 31 Substrate 12, 14, 34 Insulating layer 13, 35 Magnetostrictive layer 15, 32 Magnetoresistive element 16a, 16b, 33a, 33b Input / output terminal 17, 23, 37 Magnetic flux 21 Non-magnetic lead wire 22a, 22b Terminal 36a, 36b Magnet layer

Claims (18)

[Claims] 1. A method comprising: a ferromagnetic layer having magnetostriction; a ferromagnetic layer having a magnetoresistive effect; magnetic field generating means for exciting these ferromagnetic layers; A mechanical quantity sensor, which detects a change in magnetic flux density passing through the ferromagnetic layer due to a change in magnetic characteristics due to the change in resistance value due to a magnetoresistive effect. 2. The mechanical quantity sensor according to claim 1, wherein the direction of the magnetic field that excites the ferromagnetic layer is substantially parallel to the direction of the stress. 3. The mechanical quantity sensor according to claim 1, further comprising an electrical insulating layer between the substrate and the ferromagnetic layer having magnetostriction. 4. The mechanical quantity sensor according to claim 1, further comprising an electrically insulating layer between the ferromagnetic layer having magnetostriction and the ferromagnetic layer having a magnetoresistive effect. 5. The mechanical sensor according to claim 1, wherein the ferromagnetic layer having a magnetoresistive effect is connected to the power input / output terminal. 6. A non-magnetic layer that magnetically separates a ferromagnetic layer having magnetostriction and a ferromagnetic layer having a magnetoresistive effect, and the excitation of these ferromagnetic layers is magnetic. The mechanical sensor according to claim 1, which is made by a current flowing through a ferromagnetic layer having a resistance effect. 7. The mechanical quantity sensor according to claim 6, wherein the ferromagnetic layer and the non-magnetic layer are formed by a vapor phase film formation method or a liquid phase film formation method. 8. A ferromagnetic layer having magnetostriction, a ferromagnetic layer having a magnetoresistive effect, a nonmagnetic conductive layer formed at a position sandwiched between these ferromagnetic layers, and these electrically A non-magnetic insulating layer for insulation is provided, and excitation of these ferromagnetic layers is performed by a current flowing through the conductor layer.
The mechanical quantity sensor described in. 9. The mechanical quantity according to claim 8, wherein the non-magnetic conductive layer is connected to a power input / output terminal different from the power input / output terminal to which the ferromagnetic layer having a magnetoresistive effect is connected. Sensor. 10. The mechanical quantity sensor according to claim 8, wherein the ferromagnetic layer, the non-magnetic conductor layer and the non-magnetic insulating layer are formed by a vapor phase film forming method or a liquid phase film forming method. 11. Two ferromagnetic layers having magnetostriction are present substantially parallel to each other when viewed from the cross-sectional direction, and the ferromagnetic layer and the ferromagnetic layer are substantially provided in a gap portion between the two ferromagnetic layers. A ferromagnetic layer having a magnetoresistive effect arranged in parallel with the magnetic layer, and a magnet layer for exciting these ferromagnetic layers outside both of the two magnetostrictive ferromagnetic layers. 1. The mechanical quantity sensor according to 1. 12. The mechanical quantity sensor according to claim 11, wherein the ferromagnetic layer and the magnet layer are formed by a vapor phase film formation method or a liquid phase film formation method. 13. The mechanical quantity sensor according to claim 1, wherein the ferromagnetic layer having magnetostriction is an amorphous magnetostrictive alloy. 14. The amorphous magnetostrictive alloy is Fe—Cr.
-Si-B system, Fe-Nb-Si-B system, Fe-VS
i-B system, Fe-Co-Si-B system, Fe-W-Si-
B system, Fe-Ni-Cr-Si-B system, Fe-Ni-N
The mechanical quantity sensor according to claim 13, wherein the mechanical quantity sensor is at least one selected from b-B type and Fe-Ni-Mo-B type. 15. The amorphous magnetostrictive alloy is Fe ₇₅ Cr.
The mechanical quantity sensor according to claim 14, which is ₄ Si _12.5 B _8.5 . 16. A ferromagnetic layer having a magnetoresistive effect,
The mechanical quantity sensor according to claim 1, which is a NiFe alloy film. 17. The electrically insulating layer is SiO _2.
Alternatively, the mechanical quantity sensor described in 7. 18. The mechanical sensor according to claim 1, wherein the substrate is selected from metal, glass or ceramics.