JPH08201190A - Force detection device - Google Patents

Abstract

PURPOSE: To provide a high sensitive detection device with a simple configuration wherein a strain-generating body being subjected to force action, and a resistance element changing electrical resistance according to the amount of strain are provided and the resistance element is provided, with a first part which is fixed to the surface of the strain-generating body and a second part separated from the surface. CONSTITUTION: A resistance element 1 consists of silicon, the lower portions of both edges of the first part are fixed to a semiconductor substrate 2 of a strain-generating body, and at the same time an edge part which is a second portion and the site of the edge part are constituted separately from the surface of the substrate 2. Then, constant current or constant voltage is fed from contact parts 4a and 4b to the element 1. Also, the voltmeter of Al wires 3a and 3b continuously measures the voltage value of passing current, where the electrical resistance of the element 1 varies according to the distortion of the substrate 2 when the substrate 2 is distorted. The value of variation is immediately detected, outputted to an operation circuit, and is calculated as the physical amount of force. In this manner, since the flexible part of the element 1 is away from the surface of the substrate 2, the amount of strain of the element 1 becomes larger than that of the substrate 2, thus improving detection sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force detecting device for detecting a force exerted on various devices and the like accompanied by movement, for example, a physical quantity such as acceleration, pressure or magnetism.

[0002]

2. Description of the Related Art In various kinds of equipment that accompanies exercise, it is necessary to detect physical quantities such as acceleration, force magnitude, pressure, magnetic strength, etc., that accompany movement of the equipment.
Conventionally, as a means for detecting a physical quantity generated by the action of such a force, a force detection apparatus using a resistance element having a piezoresistive effect in which an electric resistance changes in response to mechanical deformation has been proposed. .

For example, in the acceleration detecting device disclosed in Japanese Patent Laid-Open No. 63-266358, a minute resistance element is formed on the surface of a semiconductor substrate (hereinafter referred to as "strain element") which is partially bent by receiving a force. The weight is arranged and is provided with a weight that swings on the back side when a specific force is applied.

In this acceleration detecting device, when the weight is subjected to a force due to the acceleration caused by the movement of the device, the strain-generating body is bent, so that the resistance element provided on the surface of the strain-generating body is deformed to cause resistance. The electric resistance of the element changes. This change in the electric resistance value corresponds to the magnitude of the force acting on the weight due to the acceleration caused by the movement of the device. That is, in this acceleration detecting device, the force acting on the weight, that is, the acceleration caused by the movement of the device, is detected by measuring the change in the electric resistance value.

The force detecting device having such a configuration is not limited to the above-mentioned acceleration, but is configured such that, for example, the weight body portion is oscillated by the pressure to detect the pressure, or the weight body portion is magnetic. It is also possible to detect the magnetism by configuring so that the magnitude of the swing changes depending on the strength, and a detector for detecting such pressure or magnetism has also been proposed.

Here, as the shape of the resistance element used in such a force detecting device, the shape of a general resistance element which has been conventionally proposed is shown in FIGS.

FIG. 5A shows a resistance element 51 of the force detecting device.
FIG. 5B is a sectional view showing a part, and FIG. 5B is a perspective view showing a sectional structure when the resistance element 51 and the semiconductor substrate 52 are cut at the position W in FIG. 5A.

In FIG. 5, a rectangular parallelepiped resistance element 51 is embedded in a semiconductor substrate 52 which is a strain generating body to form a semiconductor substrate 5.
The resistance element 51 is bent together with the semiconductor substrate 52 by being integrated with the semiconductor substrate 52.

Further, Al (aluminum) wirings 53a and 53b are connected to both ends of the resistance element 51, and a constant current or voltage is supplied from a power source (not shown) to the resistance element 51.
Is supplied to The Al (aluminum) wiring 53
The insulating film 54 electrically separates a and 53b from the semiconductor substrate 52.

Further, in FIG. 6, the resistance element 61 to be embedded in the semiconductor substrate 62 has a U-shape to prevent the influence of dark current generated on the substrate surface and improve the S / N ratio.
It has a structure with improved sensitivity.

FIG. 6A shows a resistance element 61 of the force detecting device.
6B is a cross-sectional view showing a portion, and FIG. 6B is a perspective view showing a cross-sectional structure when the resistance element 61 and the semiconductor substrate 62 are cut at the position W in FIG. 6A.

In this case as well, Al is formed on both ends of the resistance element 61.
(Aluminum) wirings 63a and 63b are connected to each other, and a constant current or voltage is supplied to the resistance element 61 from a power source (not shown). The Al (aluminum) wirings 63a and 63b and the semiconductor substrate 62 are electrically separated by the insulating film 64.

As described above, the force detecting device is for deforming the resistance element embedded in the substrate by bending the substrate connected to the weight such as the weight body according to the force acting on the weight. As this resistance element, an element whose electric resistance is changed by a piezoresistive effect according to mechanical deformation is used. That is, it is possible to measure the physical quantity (magnitude) of the force by continuously measuring the deformation of the strain element due to the force to be measured as a change in the electrical resistance of the resistance element.

[0014]

However, in order to increase the detection sensitivity in the force detecting device having such a structure, it is necessary to determine the physical quantity of the force to be detected, such as force, acceleration, pressure, magnetism, etc. Even such a thing is difficult for the following reasons.

For example, as a method of increasing the detection sensitivity, it is conceivable to reduce the thickness of the semiconductor substrate that is the strain generating element to increase flexibility and improve the detection sensitivity. If so, problems such as cracking occur in the manufacturing process and the yield is reduced. Therefore, when the strain generating element is formed of a semiconductor substrate, the thickness that can be configured by the current technology is 10
The limit is about μm, and there is a limit to reducing the thickness of the semiconductor substrate to improve the sensitivity.

As another method, it is possible to increase the electric resistance of the resistance element or increase the current flowing through the resistance element to increase the voltage ratio before and after the deformation of the resistance element. There is a restriction on the electric resistance of the resistance element that can be formed on the semiconductor substrate that is the body and the electric current that can flow through the resistance element, and the electric resistance value and the electric current value cannot be made too large.

To describe this restriction concretely, since the resistance element is formed by micromachining, Joule heat is generated when a large amount (excessive) current is applied, and this heat increases the possibility of deformation. In addition, if the resistance element is deformed by excessive heat, its accuracy deteriorates and accurate measurement cannot be performed.
Furthermore, Joule heat causes an error, which lowers the accuracy of the obtained measured value.

As another method for increasing the detection sensitivity,
It is also possible to increase the diameter of the semiconductor substrate, which is a strain generating body, to increase the mechanical deformation induced by the force to be detected to improve the detection sensitivity, but with this configuration, the entire device becomes larger. Therefore, when the flexure element is composed of a semiconductor substrate, there arises a problem that the chip size becomes large and the cost increases.

Further, as another method for increasing the detection sensitivity,
It is also possible to improve the detection sensitivity by making the weight placed on the back surface of the strain-flexing body a weight with a large mass so that the strain-generating body will be deformed significantly by a small force, but processing a weight with a large mass It is difficult to do so with the current technology, and trying to forcibly manufacture a weight having a large mass causes a decrease in yield, which is a problem.

Therefore, it is an object of the present invention to obtain a force detection device of such a force detection device whose detection sensitivity is improved regardless of the force to be detected. Another object is to obtain a highly sensitive force detection device with a simple structure.

[0021]

[Means for Solving the Problems] To achieve the above object,
In the invention according to claim 1 of the present invention, it is provided with a flexure element that is subjected to the action of force, and a resistance element that changes the electrical resistance value according to the amount of mechanical strain due to the action of force on this flexure element. In the force detection device, the resistance element has a micro-bridge structure having a first portion fixed to the surface of the strain-generating body and a second portion separated from the surface of the strain-generating body. Are proposing things.

The invention of claim 2 proposes the force detecting device of claim 1 in which a flexible substance is filled between the second portion of the resistance element and the strain generating body. are doing.

[0023]

Function: A bending stress such as a tensile force or a compressive force acts on the resistance element provided in the flexure element depending on the flexure of the flexure element. At this time, the stress acting on the resistance element is The size of the strain body changes depending on the position, in other words, the distance from the neutral plane of the flexure element. This situation will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view showing a state in which the strain generating element 32 (semiconductor substrate) including the resistance element 31 receives bending stress and is deformed.

In FIG. 3, the longitudinal principal axis direction of the flexure element 32 is the X direction, the thickness direction of the flexure element 32 is the Y direction, and the neutral axis direction of the flexure element 32 is the Z direction. When such bending stress occurs, the direction of the stress acting in the X direction, out of the stress acting on the flexure element 32, is opposite to the neutral plane α. That is,
The stress is tensile stress above the neutral plane α and compressive stress below.

Therefore, the distance from the center of curvature O to the neutral surface α is R, the distance from the neutral surface α to the surface of the resistance element 31 on the neutral surface side is n, and the distance from the neutral surface α to the surface of the strain element 32 is. Is n1, the central angle with respect to the resistance element having the center of curvature O as its apex is dθ, the stress in the X direction is σx, the stress in the Y direction is σy, and the nominal strain in the Z direction is 0, the resistance element 31
The balance in the Y direction of the force acting on can be expressed by the following equation (1).

(Σy + dσy) (R + n + dn) dθdz-2σxdndzsin (dθ / 2) -σy (R + n) dθdz = 0 (1) Expression

Further, by rearranging the above (1), the following equation (2) can be derived.

(R + n) (dσy / dn) = σx−σy (2) Formula

Further, in the case of FIG. 3, it is assumed that the nominal strain in the Z direction is 0, so that the equivalent stress σ ₀ acting on the resistance element 31 is expressed by the following equation (3). be able to.

Σ ₀ = √3 | σx−σy | / 2 Equation (3)

By substituting the equation (2) into the equation (3), the following equation (4) can be derived.

Σ ₀ = √3 | (R + n) (dσy / dn) | / 2 (4)

From this equation, it is found that the stress acting on the resistance element 31 in a certain strain element 32 is proportional to the distance from the neutral plane α, in other words, the stress acting on the resistance element 31 is equal to the strain element 32. It can be seen that the distance increases from the neutral plane α. This is not limited to plane distortion where Z = 0, but Z
It goes without saying that it is also valid for vertical distortion that is not ≠ 0.

Therefore, according to the first aspect of the invention, there is provided a first portion for fixing the resistance element provided on the strain-generating body to the surface of the strain-generating body, and a second portion formed at a position distant from the surface of the strain-generating body. The force detection device has a micro-bridge structure.

The first portion may be of a structure that directly or indirectly contacts the strain-generating body and transmits the force due to the strain of the strain-generating body to the second portion. The second portion may be embedded or embedded. It does not have to be arranged on the surface of the strain-generating body by sticking or the like, but may be arranged so as to be present at a position spaced apart from the surface of the strain-generating body.

That is, according to the first aspect of the invention, when the weight is oscillated and the strain-generating body is deformed in accordance with the movement of the device in which the force detecting device is installed, the stress received by the strain-generating body passes through the first portion. Is transmitted to the second part. The second portion of the resistance element that is deformed accordingly is located farther from the surface of the strain-generating body, and thus is located farther from the neutral plane than in the past. for that reason,
The stress applied to the resistance element is larger than in the conventional case. In other words, the deformation amount of the resistance element of the present invention is larger than that of the resistance element provided on the surface of the flexure element or in the flexure element.

Therefore, the amount of change in the electric resistance of the resistance element when the strain element is deformed by the action of the force to be detected becomes large, and the voltage of the resistance element before and after the strain element is deformed. The increased ratio allows for more sensitive force measurements.

The detection sensitivity of the force detecting device is improved as the second portion of the resistance element provided inside the strain-generating body is further away from the neutral plane of the strain-generating body. It is structurally unfavorable for the two parts to separate from the neutral surface in the direction toward the back surface side of the strain body, and inevitably separate from the neutral surface in the direction toward the front surface side of the strain body. .

The placement of the second portion of the resistance element is basically better as it is farther from the surface of the strain generating element, but the placement of the second portion of the resistance element that can be actually configured is not the same as in the present technology. Since the limit is a position separated by about 0.5 μm to 3 μm from the surface of the strain generating element, the second portion of the resistance element may be arranged so as to stay within this range in the present invention. In view of this, a preferable arrangement is a position separated by about 1 μm from the surface of the flexure element.

Further, if the thickness of the resistance element is made as thin as possible, the amount of deformation of the resistance element increases, so that the amount of change in the electric resistance of the resistance element when deformed by the action of force increases, and the resistance element deforms. This is preferable because the voltage ratio before and after the deformation is further increased and the sensitivity is improved.

Of course, this is not limited to the thickness, and it goes without saying that the same applies when the width of the resistance element is reduced or the length of the resistance element in the longitudinal direction is increased.
Therefore, the thickness, width, and length in the longitudinal direction of the resistance element may be determined as necessary.

In general, a plurality of resistance elements are often provided on the strain generating body which is the substrate of the force detecting portion of the force detecting device, but in the present invention, all the resistance elements provided on the strain generating body are provided. May be formed into a microbridge shape, or, of course, a structure in which a microbridge resistance element is provided only at a predetermined location (for example, a specific location or a symmetrical location with respect to a specific direction) It is sufficient to determine the number of micro-bridge-shaped resistance elements as needed.

Examples of materials forming such a resistance element include P-type single crystal silicon, N-type single crystal silicon, P-type or N-type polycrystalline silicon, PZT (lead zirconate titanate; Pb (Zr, ti) O ₃ ), a group of (piezoelectric) substances such as perovskite-based substances and Rochelle salts. Among these, if a silicon-based material is used, it is possible to easily form the resistance element by using the silicon process technology that has been established conventionally.

According to a second aspect of the present invention, a force detecting device is provided which includes a resistance element having a structure in which a flexible substance is filled between the second portion of the resistance element and the strain generating element as described above. The device.

That is, when the strain generating element is deformed, the deformation state (force generated by the strain element) is transmitted to the second portion of the resistance element through the flexible substance, so that the deformation of the resistance element occurs. The deformation of the strain body is reflected, and the change amount of the detected electric resistance, that is, the accuracy of the measured value is improved.

Preferably, by using a material having a slightly higher degree of flexibility than the strain generating element or the resistance element, the amount of change in electric resistance detected by more reliably and accurately reflecting the deformation of the strain generating element, that is, , The accuracy of the measured value is further improved.

Further, with such a structure, since the flexible material holds the resistance element, a defect due to a physical load such as a breakage of a part of the resistance element during manufacturing is generated. The manufacturing yield is improved. Further, since it is possible to prevent the detection accuracy and the sensitivity from deteriorating due to the defect of the resistance element, the connection failure, and the like, it is possible to obtain the force detection device having good performance. Examples of such a flexible material include a SiN film, a PSG film, a BPSG film, and a polyimide film.

Further, the micro-bridge type resistance element is
It can be easily formed by the following three steps. That is, the three steps are a sacrificial layer patterning step of forming a sacrificial layer on the substrate and forming at least two holes which will be the mold of the first portion of the resistance element in this layer, and a piezoresistive effect on the patterned sacrificial layer. A resistive element forming step of forming a film having the same, leaving a region between the two holes as a second portion of the resistive element, and removing the other portion to form a microbridge-shaped resistive element; and a sacrificial layer. And a sacrifice layer removing step.

In the case of a structure in which a flexible material is filled between the second portion of the microbridge-shaped resistance element and the strain generating element disclosed in the invention of claim 2, this sacrificial layer can be used as a sacrificial layer in advance. By using the flexible material, it is not necessary to perform the sacrifice layer removing step of removing the sacrifice layer, which is the third step, so that the manufacturing labor can be saved and the cost can be reduced, so that the manufacturing efficiency can be improved. Can be improved.

Further, with such a method, it is easy to reduce the film thickness of the second portion, so that it is possible to efficiently obtain a resistance element with improved detection sensitivity.

In addition to the lift-off method, as a method for manufacturing an element, a method of etching a substrate, a method of applying a technique such as micromachining, and a method of laminating a first portion and a second portion, which are separately formed, can be cited. However, the present invention is not limited to these.

[0052]

The present invention will be described in more detail based on the following examples. FIG. 4 shows an acceleration detecting device that detects acceleration by detecting the intensity of force generated by acceleration, as an example of a force intensity detecting device that uses a resistance element.

FIG. 4A shows a plan view of an acceleration detecting device in which an acceleration detecting circuit is formed on the semiconductor substrate 42. In FIG. 4A, a portion 41 indicated by a thick line is a resistance element, and in this example, the acceleration detection circuit has a structure including 12 resistance elements 41. A shaded portion 43 is an Al (aluminum) wiring, and a constant voltage or constant current is supplied from a power source (not shown). The voltage of each resistance element is measured by a voltmeter (not shown).

The front surface of the semiconductor substrate 42, which is a strain generating element, is formed flat, but the back surface thereof is thin in a donut shape (hereinafter referred to as a flexible portion 46) with the center of the semiconductor substrate 42 as a central region. Has been formed. The flexible portion 46 is provided to facilitate the bending of the semiconductor substrate 42, whereby the weight body 4 described later of the semiconductor substrate 42 is provided.
It flexes in response to the swing of 7.

The resistance element 41 is disposed above the flexible portion 46, and when the semiconductor substrate 42 bends as the weight body 47 provided at the center on the back surface side of the semiconductor substrate 42 swings, the resistance element 41 is bent. 41 is also configured to be deformed together.

FIG. 4B is a schematic view showing a cross section taken along the dotted line M. In FIG. 4B, a weight body 47 that swings when acceleration is applied is provided at the center position of the back surface of the semiconductor substrate 42.
A flexible portion 46 for increasing the amount of deformation by the weight body 47 is formed in the area around the arrangement portion of 7. The semiconductor substrate 42 is fixed on a pedestal 48.
Are arranged so as not to come into contact with the weight body 47 even if the weight body 47 swings strongly.

Therefore, when the entire apparatus moves along with the movement of the equipment provided with the acceleration detecting device, the weight body 47 is accelerated, and this acceleration is in the movement direction of the equipment in accordance with the magnitude thereof. In order to swing 47, the semiconductor substrate 42 connected to the weight body 47 bends with the swing of the weight body 47, and the resistance element 41 provided on the semiconductor substrate 42 also swings the weight body 47. It will be transformed accordingly.

As shown in FIG. 4A, the resistance elements 41 are arranged radially around the weight body 47. Therefore, the resistance element 41 is deformed as the weight body 47 swings. The change state of the electric resistance of each resistance element 41 also differs depending on the place where the element 41 is arranged. Therefore,
By continuously measuring the voltage of each resistance element 41, the acceleration direction and the magnitude of the acceleration of the device can be known.

FIG. 1 is a schematic view showing an embodiment of the resistance element portion of the present invention. FIG. 1A is a cross-sectional view of the resistance element portion, and FIG. 1B is W in FIG.
FIG. 6 is a perspective view showing a cross-sectional structure when the resistance element 1 and the semiconductor substrate 2 are cut at the position.

The resistance element 1 is made of P-type single crystal silicon whose electric resistance is changed by the piezoresistive effect, and the lower ends of both ends which are the first parts thereof are fixed to the semiconductor substrate 2 which is a strain element, and A portion between the two end portions (hereinafter, referred to as a flexible portion of the resistance element) has a micro-bridge shape separated from the surface of the semiconductor substrate 2.

As the substance forming the resistance element 1,
Not limited to the P-type single crystal silicon shown in the first embodiment, for example, N-type single crystal silicon, P-type or N-type polycrystalline silicon, PZT (lead zirconate titanate; Pb (Zr, ti) O ₃ ), A perovskite-based substance, a group of (piezoelectric) substances such as Rochelle salt, and the like, whose electrical resistance changes due to the piezoresistive effect.

Contact portions 4a and 4b made of a P type diffusion layer are provided at positions where the resistance element 1 and the semiconductor substrate 2 are in contact with each other, and the contact portions 4a and 4b are made of Al.
It is configured to be connected to the (aluminum) wirings 3a and 3b. Furthermore, this Al (aluminum) wiring 3a, 3
b is electrically insulated from the semiconductor substrate by the silicon oxide film 5 which is an insulating film.

The type of the contact portion may be the same as the type of the resistance element. In the first embodiment, since the resistance element 1 is made of P type silicon, the contact portion 4 is formed.
A and 4b are also P-type diffusion layers similar to the resistance element 1.
Of course, the present invention is not limited to this, and when the resistance element is made of N-type silicon, the contact portion may have another structure such as an N-type diffusion layer.

A constant current or a constant voltage from a power source (not shown) is supplied to the contact portions 4a and 4b through Al (aluminum) wirings 3a and 3b.
Therefore, a constant current or a constant voltage is always supplied to the resistance element 1 from the contact portions 4a and 4b. Also, Al (aluminum) wiring 3a, 3b
Is connected to a voltmeter (not shown) to continuously measure the voltage value of the current passing through the Al (aluminum) wirings 3a and 3b.

Here, when the semiconductor substrate 2 is distorted by the influence of the force (acceleration or the like) to be measured, the flexible portion of the resistance element is also distorted according to this distortion, so that the electric resistance value of the resistance element 1 is a semiconductor. It will change according to the distortion of the substrate 2.

As described above, the resistance element 1 is always supplied with a constant current or a constant voltage, and the voltage value is continuously detected by a voltmeter (not shown). When the electric resistance value changes according to the strain of, the amount of change is immediately detected. The detected amount of change is output to an arithmetic circuit (not shown), where it is calculated as a physical amount of force to be measured.

As described above, in the first embodiment, since the flexible portion of the resistance element has a micro-bridge shape separated from the surface of the semiconductor substrate 2, the resistance element 1 has a larger strain than the semiconductor substrate 2. The amount of distortion increases and the sensitivity of the detected value improves.

Further, if the thickness of the flexible portion of the resistance element is reduced, the sensitivity of the detected value is improved accordingly. Therefore, the preferable range of the thickness of the flexible portion of the resistance element is 0.1 μm.
It is preferable to set the thickness to about 10 μm. In the first embodiment, as a preferable example, the thickness of the flexible portion of the resistance element is 1 μm.

Further, the further the flexible portion of the resistance element is from the surface of the semiconductor substrate 2, the more the sensitivity of the detected value is improved. However, in consideration of the strength of the resistance element 1, the manufacturing conditions, etc., the semiconductor substrate 2 It is preferable to have a structure separated from the surface of the substrate by about 0.5 μm to 3 μm.
The structure is separated by about m.

The length of the resistance element 1 with respect to the longitudinal direction is 10 μ in consideration of the strength of the resistance element 1, the manufacturing conditions, and the like.
The thickness is preferably about m to 500 μm, and in the present embodiment, about 100 μm is a preferable example. Needless to say, these numbers (thickness of the flexible portion of the resistance element, and the distance from the surface of the semiconductor substrate and the length in the longitudinal direction) are examples and are not limited to these.

FIG. 2 is a schematic view of a resistance element portion according to another embodiment of the force detecting device of the present invention. Figure 2 (a)
2B is a cross-sectional view of the resistance element portion, and FIG.
It is a perspective view which shows the structure of a cross section when the resistance element 21 and the semiconductor substrate 22 are cut | disconnected in the position of W in (a).

The resistance element 21 is made of N-type polycrystalline silicon whose electric resistance changes by the piezoresistive effect, and both ends which are the first parts thereof are fixed to the semiconductor substrate 22 which is a strain element, and A portion between the two end portions (hereinafter, referred to as a flexible portion of the resistance element) has a microbridge shape separated from the surface of the semiconductor substrate 22.

The material forming the resistance element 21 is not limited to the N-type polycrystalline silicon shown in the second embodiment, but may be, for example, P-type polycrystalline silicon, P-type or N-type single crystal silicon, PZT. (Lead zirconate titanate; Pb (Zr, ti)
O ₃ ), perovskite-based substances, a group of (piezoelectric) substances such as Rochelle salts, and the like, whose electrical resistance changes due to the piezoresistance effect may be used.

Further, in the second embodiment, the semiconductor substrate 22
Of the highly flexible substance 25 (hereinafter, referred to as a SiN film or a PSG film) between the surface of the element and the flexible portion of the resistance element.
It is referred to as a filling member 25. ) Is filled. The substance that can be filled in here is a flexible substance, but if the substance is more flexible than the semiconductor substrate 22 and the resistance element 21, the action due to the stress acting on the strain generating element is more reliably transmitted to the resistance element. It is possible to do so, which is preferable.

Further, at the position where the resistance element 21 and the semiconductor substrate 22 are in contact with each other, the contact portion 2 made of an N type diffusion layer is formed.
4a and 24b are provided, and the contact portion 24
a and 24b are Al (aluminum) wirings 23a and 23b
It is configured to connect with. Further, the Al (aluminum) wirings 23a and 23b are electrically insulated from the semiconductor substrate by the silicon oxide film 26 which is an insulating film.

In the second embodiment, since the resistance element 21 is made of N type silicon, the contact portion 2
4a and 24b are the same N-type diffusion layers as the resistance element 21, but, for example, when the resistance element is made of P-type silicon, the contact portion is also a P-type diffusion layer.
The type of the contact portion may be the same as the type of the resistance element.

A constant current or a constant voltage from a power source (not shown) is applied to the contact portions 24a and 24b by Al.
It is supplied via (aluminum) wirings 23a and 23b. Therefore, a constant current or a constant voltage is always supplied to the resistance element 21 from the contact portions 24a and 24b. Also, Al (aluminum)
A voltmeter (not shown) is connected to the wirings 23a and 23b, and the voltage value of the current passing through the Al (aluminum) wirings 23a and 23b is continuously measured.

Here, when the semiconductor substrate 22 is distorted by the influence of the force (acceleration or the like) to be measured, the state of this distortion is transmitted to the flexible portion of the resistance element through the filling member 25. The flexible portion of the element is distorted according to the distorted state of the semiconductor substrate 22, and the electric resistance value of the resistance element 21 is changed according to the strain of the semiconductor substrate 22.

As described above, the resistance element 21 is always supplied with a constant current or a constant voltage, and the voltage value is continuously detected by a voltmeter (not shown). When the electric resistance value changes according to the strain of, the amount of change is immediately detected. The detected amount of change is output to an arithmetic circuit (not shown), where it is calculated as a physical amount of force to be measured.

Here, in the second embodiment, the filling member 25
Is configured to hold the resistance element 21, the thickness of the flexible portion of the resistance element can be reduced as compared with the case where the filling member 25 is not provided. That is, if the thickness of the flexible portion of the resistance element is reduced, the sensitivity of the detected value is improved, and thus a highly sensitive force detection device can be obtained.

A preferable range of the thickness of the flexible portion of the resistance element is about 0.1 μm to 10 μm. In the second embodiment, as a preferable example, the thickness of the flexible portion of the resistance element is 0. It is set to 5 μm.

Further, the further the flexible portion of the resistance element is from the surface of the semiconductor substrate 2, the more the sensitivity of the detected value is improved, but the semiconductor substrate 22 is considered in consideration of the strength of the resistance element 21, the manufacturing conditions, and the like. It is preferable to have a structure separated from the surface of the substrate by about 0.5 μm to 3 μm.
The structure is separated by about 1 μm.

Further, the length of the resistance element 21 in the longitudinal direction is set to 1 in consideration of the strength of the resistance element 21, the manufacturing conditions, and the like.
The thickness is preferably about 0 μm to 500 μm, and in this embodiment, a preferable example is about 100 μm. Of course,
Needless to say, these numbers (thickness of the flexible portion of the resistance element, and the distance from the surface of the semiconductor substrate and the length with respect to the longitudinal direction) are not limited to these.

As described above, in the second embodiment, the flexible portion of the resistance element is not only in the shape of a microbridge formed apart from the surface of the semiconductor substrate 22, but also the surface of the semiconductor substrate 22 and the resistance element are flexible. Flexible filling member 25 between the flexible portion
Therefore, the strained state of the surface of the semiconductor substrate 22 can be reliably transmitted to the resistance element 21.

Further, since the filling member 25 is configured to hold the resistance element 21, the resistance element 21 can be made thinner than in the case where the filling member 25 is not provided, so that a force detecting device with improved sensitivity is obtained. As a matter of course, the rate of occurrence of defects such as breakage of a part of the resistance element 21 due to a physical load during manufacturing is reduced, and the manufacturing yield can be improved.

[0086]

As described above, according to the present invention, it is possible to easily detect a physical quantity to be detected with higher sensitivity than conventional ones, regardless of the force to be detected. Become.

Further, since the strain generating element and the resistance element are separated from each other, it is not only easy to reduce the thickness of the resistance element to improve the sensitivity of force detection, but also the manufacturing yield accompanying this. Does not cause a drop in

Furthermore, in the case of the structure in which the filling member is provided between the strain generating element and the resistance element, the stress acting on the strain generating element can be transmitted to the resistance element more reliably, and the certainty of the detected value is improved. The force detection device can be obtained.

Further, since the filling member is configured to hold the resistance element, it is not necessary to consider the strength of the resistance element, and the thickness of the resistance element can be made thinner than the case where the filling member is not provided. It is possible to obtain a force detection device having improved characteristics.

In addition, since the filling member is configured to hold the resistance element, it is possible to suppress a defect occurrence rate such as breakage of a part of the resistance element due to a physical load during manufacture. The retention can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a resistance element portion according to an embodiment of a force detection device of the present invention.

FIG. 2 is a schematic view of a resistance element portion according to another embodiment of the force detection device of the present invention.

FIG. 3 is a schematic cross-sectional view showing a state in which a strain generating element including a resistance element is deformed by bending stress.

FIG. 4 is an explanatory diagram showing a configuration example of an acceleration detection device.

FIG. 5 is an explanatory diagram showing the shape of a conventionally proposed resistance element.

FIG. 6 is an explanatory diagram showing another shape of a conventionally proposed resistance element.

[Explanation of symbols]

1, 21, 31, 41, 51, 61: Resistance elements 2, 22, 32, 42, 52, 62: Semiconductor substrates 3a, 3b, 23a, 23b, 43: Al (aluminum) wiring 53a, 53b, 63a, 63b : Al (aluminum) wiring 4a, 4b, 24a, 24b: Contact part 25: Filling member 54, 64: Insulating film 5, 26: Silicon oxide film 46: Flexible part 47: Weight body 48: Pedestal

Claims (2)

[Claims] 1. A force detection device comprising: a strain-generating body that receives a force action; and a resistance element that changes an electric resistance value according to a mechanical strain amount due to a force action on the strain-generating body. The resistance element has a micro-bridge-like structure having a first portion fixed to the surface of the strain-generating body and a second portion separated from the surface of the strain-generating body. Force detection device. 2. The force detecting device according to claim 1, wherein a flexible substance is filled between the second portion of the resistance element and the strain-generating body.