Stress sensor

Abstract

Provided is a stress sensor having: a substrate (10); and an element (20) that is formed on the substrate (10) and that has a first magnetization layer (21), a second magnetization layer (22) in which a change in the magnetization direction when distortion is applied to the substrate (10) is larger than that of the first magnetization layer (21), and a spacer layer (23) disposed between the first magnetization layer (21) and the second magnetization layer (22). In a state in which distortion is not applied to the substrate (10), at least one of the magnetization direction (21m) of the first magnetization layer (21) and the magnetization direction (22m) of the second magnetization layer (22) has a component perpendicular to the in-plane direction (x) of the substrate (10).

Description

Stress Sensor

[0001] The present invention relates to a stress sensor.

[0002] In recent years, sensors capable of measuring stress using magnetic materials have been developed.

[0003] For example, Patent Document 1 describes a pressure sensor including a base and a first sensor unit provided on the base. The first sensor unit includes a flexible first transducer thin film having a first film surface, a first strain sensing element provided on the first film surface at a position different from the center of gravity of the first film surface and including a first magnetic layer, a second magnetic layer, and a non-magnetic first intermediate layer provided between the first and second magnetic layers, and a second strain sensing element provided on the first film surface at a position different from the center of gravity and spaced apart from the first strain sensing element and including a third magnetic layer, a fourth magnetic layer, and a non-magnetic second intermediate layer provided between the third and fourth magnetic layers, and it is described that a straight line passing through the first strain sensing element and the second strain sensing element passes through the center of gravity.

[0004] Japanese Patent Application Laid-Open No. 2013-205403

[0005] However, in the pressure sensor described in Patent Document 1, the magnetization direction rotates within the plane of the thin film, so if only one element is formed on the thin film, the direction of magnetization is not determined unless strain is applied in a predetermined direction, and stress cannot be detected, particularly when stress is applied isotropically within the plane of the thin film. For this reason, it was necessary to form multiple elements on the thin film.

[0006] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a stress sensor that can reduce dependency on the direction of applied strain even when only one element is formed on a substrate, and can easily detect stress even when stress that causes strain in various directions is applied.

[0007] One embodiment of the stress sensor of the present invention that can solve the above problems is as follows: [1] A stress sensor comprising: a substrate; and an element formed on the substrate, the element having a first magnetization layer, a second magnetization layer whose magnetization direction changes more than the first magnetization layer when strain is applied to the substrate, and a spacer layer disposed between the first and second magnetization layers, wherein at least one of the magnetization directions of the first and second magnetization layers has a component perpendicular to the in-plane direction of the substrate when no strain is applied to the substrate.

[0008] In the above-mentioned stress sensor, when no strain is applied to the substrate, at least one magnetization direction has a component perpendicular to the in-plane direction of the substrate, and the magnetization direction of the second magnetization layer can rotate. Therefore, by measuring the electrical resistance value associated with changes in the magnetization direction of the second magnetization layer, even if only one element is formed on the substrate, it is possible to reduce dependence on the direction of the applied strain, and it is possible to easily detect stress even when stress that causes strain in various directions is applied.

[0009] The aneurysm treatment device of the present invention is preferably one of the following [2] to [8]. [2] The stress sensor according to [1], wherein the change in the magnetization direction rotates the magnetization direction so that it approaches a direction parallel to the in-plane direction of the substrate, or rotates the magnetization direction so that it approaches a direction perpendicular to the in-plane direction of the substrate. [3] The stress sensor according to [1] or [2], wherein the magnetization direction, which has a component perpendicular to the in-plane direction of the substrate when no strain is applied to the substrate, intersects perpendicularly with the in-plane direction of the substrate. [4] The stress sensor according to any one of [1] to [3], wherein the magnetization direction of the first magnetization layer and the magnetization direction of the second magnetization layer both have a component perpendicular to the in-plane direction of the substrate when no strain is applied to the substrate. [5] The stress sensor according to any one of [1] to [4], wherein the magnetization direction of the first magnetization layer and the magnetization direction of the second magnetization layer are the same when no strain is applied to the substrate. [6] The stress sensor according to any one of [1] to [3], wherein, when no strain is applied to the substrate, the magnetization direction of the first magnetization layer has a component perpendicular to the in-plane direction of the substrate, and the magnetization direction of the second magnetization layer does not have a component perpendicular to the in-plane direction of the substrate. [7] The stress sensor according to any one of [1] to [6], wherein the second magnetization layer is disposed closer to the substrate than the first magnetization layer. [8] The stress sensor according to any one of [1] to [7], wherein, in a plan view, the element is formed at the centroid of the substrate.

[0010] In the stress sensor of the present invention, when no strain is applied to the substrate, at least one magnetization direction has a component perpendicular to the in-plane direction of the substrate, and the magnetization direction of the second magnetization layer can rotate.Therefore, by measuring the electrical resistance value associated with changes in the magnetization direction of the second magnetization layer, even if only one element is formed on the substrate, it is possible to reduce dependence on the direction of the applied strain, and it is possible to easily detect stress even when stress is applied that causes strain in various directions.

[0011] 1 shows a plan view of a stress sensor according to an embodiment of the present invention. 2 shows a cross-sectional view taken along line II-II of the stress sensor according to the embodiment of the present invention shown in FIG. 1. 3 shows a cross-sectional view taken along line IV-IV of the stress sensor according to the embodiment of the present invention shown in FIG. 3. 4 shows a side view illustrating an example of the magnetization direction of the first magnetization layer and the magnetization direction of the second magnetization layer in the stress sensor shown in FIG. 1. 5 shows an example of the magnetization direction of the first magnetization layer and the magnetization direction of the second magnetization layer when strain is applied to the stress sensor shown in FIG. 1. 6 shows a side view illustrating another example of the magnetization direction of the first magnetization layer and the magnetization direction of the second magnetization layer in the stress sensor shown in FIG. 1. 7 shows a side view illustrating an example of the magnetization direction of the first magnetization layer and the magnetization direction of the second magnetization layer when strain is applied to the stress sensor shown in FIG. 7. 8 shows a graph illustrating an example of the change in electrical resistance in an element when tensile strain is applied to the stress sensor shown in FIG. 5. 9 shows a plan view illustrating the direction of tensile strain applied to the stress sensor shown in FIG. 7. 10 shows a plan view illustrating the direction of tensile strain applied to the stress sensor shown in FIG. 7.

[0012] The present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the illustrated examples, and it is possible to carry out the invention by making appropriate modifications within the scope that can comply with the above-mentioned and below-mentioned purposes, and all of these modifications are included in the technical scope of the present invention.

[0013] In this specification, a change in the magnetization direction refers to the amount of rotation of the magnetization direction.

[0014] The overall configuration of the stress sensor will be described with reference to Figures 1 to 11. Figures 1 to 8, 10, and 11 show configuration examples of a stress sensor 1 having a substrate 10 and an element 20. In Figures 2, 4, and 5 to 8, the in-plane direction of the substrate 10 is indicated by x, and the direction perpendicular to the in-plane direction x of the substrate 10 is indicated by y. The in-plane direction x of the substrate 10 is a direction perpendicular to the direction y perpendicular to the in-plane direction x of the substrate 10, but Figures 2, 4, and 5 to 8 only show one direction perpendicular to the direction y.

[0015] 1 to 4, the stress sensor 1 has a substrate 10. The substrate 10 serves as a base on which an element 20 (described later) is formed, and also serves to transmit applied strain to the element 20.

[0016] 1 to 4, the stress sensor 1 has an element 20. The element 20 is formed on a substrate 10. The element 20 has a first magnetization layer 21, a second magnetization layer 22 whose magnetization direction changes more than that of the first magnetization layer 21 when a strain is applied to the substrate 10, and a spacer layer 23 disposed between the first magnetization layer 21 and the second magnetization layer 22.

[0017] 5 and 7 are diagrams showing, by arrows, configuration examples of the magnetization direction 21m of the first magnetization layer 21 and the magnetization direction 22m of the second magnetization layer 22 when no strain is applied to the substrate 10. As shown in Fig. 5 and 7, when no strain is applied to the substrate 10, at least one of the magnetization direction 21m of the first magnetization layer 21 and the magnetization direction 22m of the second magnetization layer 22 has a component perpendicular to the in-plane direction x of the substrate 10.

[0018] Figure 6 shows an example of the magnetization direction 22m of the second magnetization layer 22 when stress is applied in the direction of arrow A to the stress sensor 1 shown in Figure 5, and illustrates how the magnetization direction 22m of the second magnetization layer 22, which was oriented in a direction y perpendicular to the in-plane direction x of the substrate 10 before the stress was applied, rotates to approach a direction parallel to the in-plane direction x of the substrate 10 due to the application of stress.

[0019] Figure 8 shows an example of the magnetization direction 22m of the second magnetization layer 22 when stress is applied in the direction of arrow A to the stress sensor 1 shown in Figure 7, and illustrates how the magnetization direction 22m of the second magnetization layer 22, which was oriented parallel to the in-plane direction x of the substrate 10 before the stress was applied, rotates to approach the direction y perpendicular to the in-plane direction x of the substrate 10 as a result of the stress being applied.

[0020] 5 to 8 show a state in which only the magnetization direction 22m of the second magnetization layer 22 changes in response to strain applied to the substrate 10, while the magnetization direction 21m of the first magnetization layer 21 does not change. Although not shown, the magnetization direction of the first magnetization layer may also change in response to strain applied to the substrate. In this case, the magnetization direction of the second magnetization layer changes more greatly than the magnetization direction of the first magnetization layer.

[0021] As the magnetization direction changes as described above, the electrical resistance changes. By detecting this change in electrical resistance, stress can be detected. More specifically, first, a current is applied to the element 20. For example, the current can be applied via the electrode 40 described below. Then, the electrical resistance value in the element 20 is measured. The electrical resistance value can also be measured via the electrode 40. As shown in FIGS. 7 and 8, a graph is shown in FIG. 9 showing the change in electrical resistance in the element 20 when stress is applied to the stress sensor 1 in the direction of arrow A and the magnetization direction 22m of the second magnetization layer 22 changes. Note that R Ｐ 8, represents the electrical resistance value when the magnetization direction 21m of the first magnetization layer 21 and the magnetization direction 22m of the second magnetization layer 22 are the same and point in the direction y perpendicular to the in-plane direction x of the substrate 10. Ｐ 9 represents the ratio of the increase in electrical resistance when strain is applied to the substrate 10 to the stress applied to the substrate 10. As shown in Fig. 9, a change in electrical resistance appears in the element 20 due to the stress applied to the stress sensor 1. This makes it possible to measure the degree of strain and whether or not stress is occurring.

[0022] As described above, in the stress sensor 1 according to the embodiment of the present invention, when no strain is applied to the substrate 10, at least one magnetization direction has a component perpendicular to the in-plane direction x of the substrate 10, and the magnetization direction 22m of the second magnetization layer 22 can rotate. Therefore, by measuring the electrical resistance value accompanying the change in the magnetization direction 22m of the second magnetization layer 22, even if only one element 20 is formed on the substrate 10, it is possible to reduce dependence on the direction of the applied strain, and it is possible to easily detect the stress even when the stress is applied such that strain occurs in various directions.

[0023] 1 to 4, in the stress sensor 1, only one element 20 may be formed on the substrate 10. Although not shown, multiple elements may be formed on the substrate. By forming multiple elements on the substrate, it is possible to increase the number of points on the substrate where stress is detected, making it easier to improve the accuracy of stress detection.

[0024] The change in the magnetization direction of the magnetization direction 21m of the first magnetization layer 21 and the magnetization direction 22m of the second magnetization layer 22 is preferably such that the magnetization direction rotates so as to approach a direction parallel to the in-plane direction x of the substrate 10, or so as to approach a direction y perpendicular to the in-plane direction x of the substrate 10. A configuration in which only the magnetization direction 22m of the second magnetization layer 22 rotates so as to approach a direction parallel to the in-plane direction x of the substrate 10, or so as to approach a direction y perpendicular to the in-plane direction x of the substrate 10, may also be adopted. By configuring the rotation direction of the magnetization direction as described above, the magnetization direction 22m of the second magnetization layer 22 can be rotated so that it approaches a direction parallel to the in-plane direction x of the substrate 10, or so that the magnetization direction 22m of the second magnetization layer 22 approaches a direction y perpendicular to the in-plane direction x of the substrate 10.Therefore, by measuring the electrical resistance value accompanying the change in the magnetization direction 22m of the second magnetization layer 22, it is possible to reduce dependence on the direction of the applied strain, and it is possible to easily detect the stress even when stress that causes strain in various directions is applied.

[0025] 5 and 7 , when no strain is applied to the substrate 10, the magnetization direction having a component perpendicular to the in-plane direction x of the substrate 10 preferably intersects perpendicularly to the in-plane direction x of the substrate 10. This configuration makes it possible to increase the amount of rotation when the magnetization direction 22m of the second magnetization layer 22 rotates so as to approach a direction parallel to the in-plane direction x of the substrate 10 or so as to approach the direction y perpendicular to the in-plane direction x of the substrate 10, thereby making it easier to increase the gauge factor of the element 20 and improve the sensitivity of the stress sensor 1.

[0026] FIG. 10 is a plan view of the stress sensor 1 shown in FIG. 5 , in which the arrow B indicates the direction of tensile strain applied along one in-plane axis. As shown in FIG. 5 , when no strain is applied to the substrate 10, the magnetization direction 21m of the first magnetization layer 21 and the magnetization direction 22m of the second magnetization layer 22 both have components perpendicular to the in-plane direction x of the substrate 10. When strain is applied to the substrate 10, the magnetization direction 22m of the second magnetization layer 22 can rotate to approach a direction parallel to the in-plane direction x of the substrate 10. Therefore, tensile strain along the in-plane axis as shown in FIG. 10 can be detected. With the above configuration, when no strain is applied to the substrate 10, the magnetization direction 21m of the first magnetization layer 21 and the magnetization direction 22m of the second magnetization layer 22 can be the same direction. In particular, from the viewpoint of making it easier to increase the gauge factor of element 20, it is preferable that when no strain is applied to substrate 10, the magnetization direction 21m of first magnetization layer 21 and the magnetization direction 22m of second magnetization layer 22 both intersect perpendicularly to the in-plane direction x of substrate 10.

[0027] 11 is a plan view of the stress sensor 1 shown in FIG. 7 , in which the direction of tensile strain applied isotropically in a plane is indicated by arrow C. As shown in FIG. 7 , when no strain is applied to the substrate 10, the magnetization direction 21 m of the first magnetization layer 21 has a component perpendicular to the in-plane direction x of the substrate 10, and the magnetization direction 22 m of the second magnetization layer 22 does not have a component perpendicular to the in-plane direction x of the substrate 10. When strain is applied to the substrate 10, the magnetization direction 22 m of the second magnetization layer 22 can rotate to approach the direction y perpendicular to the in-plane direction x of the substrate 10. Therefore, it is possible to detect tensile strain applied isotropically in a plane as shown in FIG. In particular, from the viewpoint of making it easier to increase the gauge factor of element 20, it is preferable that, when no strain is applied to substrate 10, magnetization direction 21m of first magnetization layer 21 is perpendicular to in-plane direction x of substrate 10, and magnetization direction 22m of second magnetization layer 22 is parallel to in-plane direction x of substrate 10.

[0028] The second magnetization layer 22 is preferably arranged closer to the substrate 10 than the first magnetization layer 21. In the element 20, the second magnetization layer 22, the spacer layer 23, and the first magnetization layer 21 are arranged in this order from the substrate 10 side, and more preferably, no other layers or members are arranged between the second magnetization layer 22, the spacer layer 23, and the first magnetization layer 21. By arranging the second magnetization layer 22 on the substrate 10 side, strain can be more efficiently transmitted to the second magnetization layer 22, which makes it easier to improve the accuracy of stress measurement. Although not shown, stress can be detected even if the first magnetization layer is arranged closer to the substrate than the second magnetization layer.

[0029] In a plan view, it is preferable that a portion of the element 20 is formed so as to overlap with the centroid of the substrate 10. Furthermore, it is more preferable that the element 20 is formed on the substrate 10 so that the centroid of the element 20 and the centroid of the substrate 10 overlap in a plan view. With this configuration, when a strain is applied to the stress sensor 1, the substrate 10 can be made to stretch isotropically, making it easier to detect the strain applied isotropically to the substrate 10.

[0030] The substrate 10 is preferably made of resin. When the stress sensor 1 is used for detecting minute stresses, it is preferably made of a flexible material. Examples of materials that can be used to make the substrate 10 include polyester, polycarbonate, and polyimide. These materials may be used alone or in combination.

[0031] The shape of the substrate 10 is not particularly limited, and can be a columnar, plate-like, rod-like, or other various shapes, but is preferably a plate-like or sheet-like shape, as shown in Figures 1 to 4. This makes it easier to detect even slight distortion. The shape of the substrate 10 in a plan view is also not particularly limited, and can be, for example, a triangle, a circle, or a square as shown in Figures 1 and 3.

[0032] The first magnetization layer 21 and the second magnetization layer 22 are made of a magnetic material. Examples of magnetic materials that make up the first magnetization layer 21 and the second magnetization layer 22 include iron, cobalt, and nickel. These materials may be used alone or in combination. The first magnetization layer 21 and the second magnetization layer 22 may be made of the same material or different materials.

[0033] The spacer layer 23 may be made of an insulator such as silicon oxide, silicon nitride, aluminum oxide, magnesium oxide, etc. These materials may be used alone or in combination.

[0034] The spacer layer 23 may be made of a non-magnetic metal such as platinum, copper, tantalum, gold, etc. These materials may be used alone or in combination.

[0035] The magnetization direction of first magnetization layer 21 when strain is applied to substrate 10 is preferably within ±10° of the magnetization direction of first magnetization layer 21 when no strain is applied to substrate 10, more preferably within ±8°, and even more preferably within ±5°, and it is particularly preferable that the magnetization direction does not change from the state when no strain is applied to substrate 10. This makes it easier to improve the accuracy of stress measurement.

[0036] The magnetoelastic coupling constant of the first magnetization layer 21 and the magnetoelastic coupling constant of the second magnetization layer 22 may be the same or different.

[0037] When the magnetoelastic coupling constant of the first magnetization layer 21 and the magnetoelastic coupling constant of the second magnetization layer 22 are different, for example, the absolute value of the magnetoelastic coupling constant of the first magnetization layer 21 is 0 J / m ３ The magnetoelastic coupling constant of the first magnetization layer 21 can be set to a value close to 0.5 MJ / m ３ or less, or 0 to 0.3 MJ / m ３ or less, or 0 to 0.1 MJ / m ３ It may be less than 0 J / m ３ The absolute value of the magnetoelastic coefficient of the second magnetization layer 22 may be 1 MJ / m ３Above, 3MJ / m ３ Above, 5MJ / m ３ The upper limit of the absolute value of the magnetoelastic coefficient of the second magnetization layer 22 is not particularly limited, but may be set to, for example, 20 MJ / m ３ It can be set to, etc.

[0038] The magnetization direction having a component perpendicular to the in-plane direction x of the substrate 10 may intersect with the in-plane direction x of the substrate 10 at an angle of, for example, 15°, 30°, 45°, 60°, or 75°.

[0039] When no strain is applied to the first magnetization layer 21 and the second magnetization layer 22, the magnetization direction can be made to tend to orient in a direction y perpendicular to the in-plane direction x of the substrate 10, or to orient in the in-plane direction x of the substrate 10, due to the interfacial magnetic anisotropy.

[0040] As an example, a stress sensor 1 will be described in which a magnetic tunnel junction element 20 is formed, in which the first magnetization layer 21 and the second magnetization layer 22 are made of CoFeB, and the spacer layer 23 is made of MgO. By thinning the CoFeB to a predetermined thickness, the perpendicular magnetic anisotropy of the CoFeB / MgO interface becomes dominant. As a result, the magnetization is oriented in the direction y perpendicular to the in-plane direction x of the substrate 10. Conversely, by increasing the CoFeB thickness to a predetermined thickness, the effect of the perpendicular magnetic anisotropy of the CoFeB / MgO interface weakens, and the magnetization is oriented in the in-plane direction x of the substrate 10.

[0041] Another example is a stress sensor 1 in which the first magnetization layer 21 and the second magnetization layer 22 are made of Co, and the spacer layer 23 is made of Pt. In this case, too, by thinning the Co to a predetermined thickness, the perpendicular magnetic anisotropy of the Co / Pt interface becomes dominant, so that the magnetization is oriented in the direction y perpendicular to the in-plane direction x of the substrate 10. Conversely, by increasing the Co thickness to a predetermined thickness, the effect of the perpendicular magnetic anisotropy of the Co / Pt interface weakens, so that the magnetization is oriented in the in-plane direction x of the substrate 10.

[0042] When the stress sensor 1 has a configuration such as CoFeB / MgO or Co / Pt as described above, the first magnetization layer 21 is formed thin to a predetermined thickness, and the second magnetization layer 22 is formed thick to a predetermined thickness, thereby forming the element 20 having the magnetization direction as shown in Fig. 7. Note that the thickness of each layer described above refers to the length of each layer in the direction y perpendicular to the in-plane direction x of the substrate 10.

[0043] 7, the direction of change in magnetic anisotropy caused by the application of isotropic in-plane tensile strain to the stress sensor 1 may be such that the magnetization tends to orient in the direction y perpendicular to the in-plane direction x of the substrate 10. In this case, the magnetization direction 21m of the first magnetization layer 21 does not change even when isotropic in-plane tensile strain is applied. On the other hand, the magnetization direction 22m of the second magnetization layer 22 rotates to orient in the direction y perpendicular to the in-plane direction x of the substrate 10.

[0044] 5, the direction of change in magnetic anisotropy caused by the application of isotropic in-plane tensile strain to the stress sensor 1 may be a direction that acts to make it easier for the magnetization to orient in the in-plane direction x of the substrate 10. The magnetization direction 21m of the first magnetization layer 21 does not change even when isotropic in-plane tensile strain is applied. On the other hand, the magnetization direction 22m of the second magnetization layer 22 rotates to orient in the in-plane direction x of the substrate 10.

[0045] 3 and 4, the surface of the substrate 10 may have an underlayer 50 for improving adhesion to the element 20. The underlayer may be made of, for example, a non-magnetic metal such as platinum, copper, tantalum, or gold, or an insulator such as silicon oxide, silicon nitride, aluminum oxide, or magnesium oxide. These materials may be used alone or in combination.

[0046] 4, the element 20 may have a protective layer 60 for protecting the element 20 on the surface of the element 20 opposite the substrate 10. The protective layer may be made of a non-magnetic metal such as platinum, copper, tantalum, or gold. These materials may be used alone or in combination.

[0047] The stress sensor 1 preferably has electrodes 40 for passing a current through the element 20. As shown in Figures 1, 2, and 5 to 8, the electrodes 40 may be disposed on the side of the element 20. As shown in Figures 3 and 4, the electrodes 40 may be disposed on the surface of the element 20 opposite the substrate 10 side, and on the underlayer 50.

[0048] This application claims the benefit of priority based on Japanese Patent Application No. 2022-018696, filed on February 9, 2022. The entire contents of the specification of Japanese Patent Application No. 2022-018696, filed on February 9, 2022, are incorporated herein by reference.

[0049] 1: Stress sensor 10: Substrate 20: Element 21: First magnetization layer 21m: Magnetization direction of first magnetization layer 22: Second magnetization layer 22m: Magnetization direction of second magnetization layer 23: Spacer layer 40: Electrode 50: Underlayer 60: Protective layer

Claims

1. A substrate; an element formed on the substrate, the element having a first magnetization layer, a second magnetization layer whose magnetization direction changes more than the first magnetization layer when a strain is applied to the substrate, and a spacer layer disposed between the first magnetization layer and the second magnetization layer; A stress sensor in which the magnetization direction of the first magnetization layer has a component perpendicular to the in-plane direction of the substrate when no strain is applied to the substrate, and the magnetization direction of the second magnetization layer is parallel to the in-plane direction of the substrate when no strain is applied to the substrate.

2. 2. The stress sensor according to claim 1, wherein the change in the magnetization direction is a rotation such that the magnetization direction approaches a direction parallel to an in-plane direction of the substrate, or a rotation such that the magnetization direction approaches a direction perpendicular to the in-plane direction of the substrate.

3. 3. The stress sensor according to claim 1, wherein a magnetization direction having a component perpendicular to an in-plane direction of the substrate when no strain is applied to the substrate intersects perpendicularly with the in-plane direction of the substrate.

4. 3. The stress sensor according to claim 1, wherein, when no strain is applied to the substrate, the magnetization direction of the first magnetization layer has a component perpendicular to the in-plane direction of the substrate, and the magnetization direction of the second magnetization layer does not have a component perpendicular to the in-plane direction of the substrate.

5. 3. The stress sensor according to claim 1, wherein the second magnetization layer is disposed closer to the substrate than the first magnetization layer.

6. 3. The stress sensor according to claim 1, wherein the element is formed at the centroid of the substrate in a plan view.

7. A stress sensor as described in claim 1 or 2, wherein a base layer composed of a material containing either silicon oxide, aluminum oxide, or magnesium oxide is provided between the substrate and the element.