JP2013245937A - Force detection element, force detection module, force detection unit, and robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force detection element, force detection module, and force detection unit that allows reduction in size; and a robot including them.SOLUTION: A force detection element includes: a crystal substrate 6; a force detection unit 10 which includes a first electrode 11 that is formed on one surface of the crystal substrate 6 and a second electrode 12 that is formed on another surface, and to which an external force is applied; a circuit unit 21 that is connected to the first electrode 11 or second electrode 12 and is on the crystal substrate 6 which is extended from the force detection unit 10; and a groove unit 27a which is arranged between the force detection unit 10 of the crystal substrate 6 and the circuit unit 21, and whose rigidity is adjusted so as to be different from the rigidity of the crystal substrate 6 from which the force detection unit 10 is formed. The circuit unit 21 includes a semiconductor element having a gate electrode.

Description

  The present invention relates to a force detection element, a force detection module, a force detection unit, and a robot.

2. Description of the Related Art A force sensor (force detection element) that captures an electric charge induced on the surface of a piezoelectric substrate by applying an external force and detects an external force applied from the change in electric charge is known (for example, see Patent Document 1).
In such a force detection element, a signal detected from the force detection element is connected to a separate detection circuit unit via a wiring to detect the magnitude of the force.

Japanese Unexamined Patent Publication No. Hei 4-231827

  In recent years, there is a demand for downsizing of the force detection element. In order to reduce the size of the force detection element including the wiring and the detection circuit, there is a proposal that a circuit unit is configured with a semiconductor element on a piezoelectric substrate in addition to a force detection unit that detects force. However, when the semiconductor element is configured on the piezoelectric substrate, the force applied to the force detection unit deforms the circuit unit and deforms the channel region of the semiconductor element. The threshold voltage of the semiconductor element may vary due to the deformation of the channel region. For this reason, it is difficult to reduce the size of the force detection element by forming the force detection unit and the semiconductor element on the piezoelectric substrate.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] A force detection element according to this application example includes a piezoelectric substrate, a first electrode formed on one surface of the piezoelectric substrate, and a second electrode formed on the other surface. An applied force detection unit; and a circuit unit in which the piezoelectric substrate extends from the force detection unit, and a semiconductor element connected to the first electrode or the second electrode is provided on the extended piezoelectric substrate; A rigidity adjusting unit adjusted to a stiffness different from the stiffness of the piezoelectric substrate on which the force detecting unit is formed, between the force detecting unit and the circuit unit of the piezoelectric substrate. And

According to this configuration, the rigidity adjusting unit adjusted to a rigidity different from the rigidity of the piezoelectric substrate of the force detecting unit is provided between the force detecting unit formed on the piezoelectric substrate and the circuit unit. As the rigidity adjusting section, a rigidity adjusting section having a lower rigidity than the piezoelectric substrate of the force detecting section or a rigidity adjusting section having a high rigidity is provided.
The external force applied to the force detection unit applies stress to the piezoelectric substrate, and this stress is also transmitted from the piezoelectric substrate of the force detection unit to the circuit unit. At this time, if the rigidity of the rigidity adjusting unit is lower than the piezoelectric substrate of the force detecting unit, the piezoelectric substrate is deformed by the rigidity adjusting unit to relieve the stress. For this reason, this stress is not transmitted to the circuit portion, the channel region of the semiconductor element formed in the circuit portion is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
Further, when the rigidity of the rigidity adjusting unit is higher than that of the piezoelectric substrate of the force detecting unit, it is possible to regulate the stress that causes the piezoelectric substrate to be deformed by the rigidity adjusting unit, thereby suppressing the deformation of the piezoelectric substrate of the circuit unit. For this reason, this stress is not transmitted to the circuit portion, the channel region of the semiconductor element formed in the circuit portion is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
As described above, since the force detection element of this application example can suppress the fluctuation of the threshold voltage of the semiconductor element, the force detection unit and the circuit unit are integrally formed on the piezoelectric substrate, which has been difficult to put into practical use. Thus, the force detection element can be reduced in size.

  Application Example 2 In the force detection element according to the application example described above, the length of the rigidity adjustment unit facing the force detection unit in a plan view in the thickness direction of the piezoelectric substrate is the length of the force detection unit of the circuit unit. It is preferable to form longer than the length facing.

According to this configuration, the rigidity adjusting unit faces the force detection unit and faces the circuit unit. And the circuit part is arrange | positioned so that the whole length which opposes the force detection part of a circuit part may oppose a rigidity adjustment part. In other words, the rigidity adjusting portion is formed between the force detecting portion and the length of the circuit portion facing the force detecting portion.
For this reason, the stress transmitted from the force detection unit is relaxed or regulated by the stiffness adjusting unit and is not transmitted to the circuit unit.

  Application Example 3 In the force detection element according to the application example described above, it is preferable that a recess is formed in the piezoelectric substrate as the rigidity adjusting unit.

  According to this configuration, the rigidity adjusting portion with low rigidity can be formed by forming the recess in the piezoelectric substrate. The concave portion can be easily formed by etching the piezoelectric substrate.

  Application Example 4 In the force detection element according to the application example described above, it is preferable that a hole penetrating the piezoelectric substrate is formed as the rigidity adjusting unit.

  According to this configuration, it is possible to form the rigidity adjusting portion with low rigidity by making the hole in the piezoelectric substrate. The hole can be easily formed by etching the piezoelectric substrate.

  Application Example 5 The force detection element according to the application example described above includes a recess formed in the piezoelectric substrate as the rigidity adjusting unit, and a soft member having a rigidity lower than that of the piezoelectric substrate embedded in the recess. It is preferable.

  According to this configuration, the concave portion is formed as the rigidity adjusting portion, and the soft member is embedded in the concave portion. In this way, the strength of the piezoelectric substrate is lowered while the rigidity is lowered by forming the concave portion, but the strength of the piezoelectric substrate is secured by adding a soft member to the concave portion, and the rigidity is adjusted. Can do.

  Application Example 6 In the force detection element according to the application example described above, a hole formed in the piezoelectric substrate as the rigidity adjusting unit, and a soft member having lower rigidity than the piezoelectric substrate embedded in the hole, It is preferable to have.

  According to this configuration, the hole is formed as the rigidity adjusting portion, and the soft member is embedded in the hole. Thus, while the rigidity is lowered by forming the hole portion, the strength of the piezoelectric substrate is lowered, but the strength of the piezoelectric substrate is secured by adding a soft member to the hole portion, and the rigidity is increased. Can be adjusted.

  Application Example 7 In the force detection element according to the application example described above, it is preferable that an additional member that adds thickness to the piezoelectric substrate is provided as the rigidity adjusting unit.

According to this configuration, the additional member that adds thickness to the piezoelectric substrate is provided as the rigidity adjusting portion. Thus, the rigidity of the rigidity adjusting portion is increased by making the thickness of the substrate thicker than that of the piezoelectric substrate.
For this reason, the stress that attempts to deform the piezoelectric substrate can be regulated by the rigidity adjusting unit, and deformation of the piezoelectric substrate in the circuit unit is suppressed.

  Application Example 8 In the force detection element according to the application example, it is preferable that the semiconductor element is a MOS type semiconductor element and includes a polysilicon TFT.

  According to this configuration, since the semiconductor element is a MOS type semiconductor element and has a polysilicon TFT, an analog circuit such as an amplifier and an AD converter and a digital circuit such as a signal processing circuit can be integrated on the piezoelectric substrate.

  Application Example 9 In the force detection element according to the application example, it is preferable that the semiconductor element is a MOS type semiconductor element, and the MOS type semiconductor element is made of an oxide-based semiconductor material.

  According to this configuration, since the MOS semiconductor element is made of an oxide semiconductor material, the process temperature in the manufacturing process can be lowered, and damage to the piezoelectric substrate can be suppressed.

  Application Example 10 In the force detection element according to the application example described above, the circuit unit includes a back gate electrode that is in direct contact with the surface of the piezoelectric substrate or via an insulating layer, an insulating film that covers the back gate electrode, The semiconductor element having a gate electrode formed on the insulating film, and in the plan view in the thickness direction of the piezoelectric substrate, the back gate electrode is provided at an overlapping position including the gate electrode, The back gate electrode is preferably connected to the ground.

According to this configuration, the back gate electrode that is in contact with the piezoelectric substrate directly or via the insulating layer is provided below the gate electrode of the semiconductor element of the circuit portion, and the back gate electrode includes the gate electrode in plan view. The back gate electrode is connected to the ground.
For this reason, even when an external force or the like is applied to the piezoelectric substrate and a charge is induced on the surface of the piezoelectric substrate, the electric field due to the induced charge can be shielded at the back gate electrode, and fluctuations in the threshold voltage of the semiconductor element can be suppressed.

  Application Example 11 In the force detection element according to the application example described above, the circuit unit is formed with a back gate electrode connected to the surface of the piezoelectric substrate, an insulating film covering the back gate electrode, and the insulating film formed on the insulating film. And the semiconductor element having the gate electrode formed, and in the plan view in the thickness direction of the piezoelectric substrate, the back gate electrode is provided at an overlapping position including the gate electrode, and the back gate electrode is fixed. It is preferable that the potential is fixed.

According to this configuration, the back gate electrode connected to the piezoelectric substrate is provided below the gate electrode of the semiconductor element of the circuit unit, and the back gate electrode is provided at a position overlapping the gate electrode in plan view. The back gate electrode is fixed at a constant potential.
For this reason, even when an external force or the like is applied to the piezoelectric substrate and a charge is induced on the surface of the piezoelectric substrate, the electric field due to the induced charge can be shielded at the back gate electrode, and fluctuations in the threshold voltage of the semiconductor element can be suppressed.

  Application Example 12 The force detection module according to this application example is a force detection module in which a plurality of piezoelectric substrates are stacked, and is orthogonal to the z-axis direction when the stacking direction of the piezoelectric substrates is the z-axis direction. When the direction is the x-axis direction, the z-axis direction, and the direction orthogonal to the x-axis direction is the y-axis direction, the first force detection element that detects the force in the x-axis direction and the force in the z-axis direction are detected. A second force detecting element and a third force detecting element for detecting a force in the y-axis direction, wherein the first force detecting element is provided on one surface of the first piezoelectric substrate and the first piezoelectric substrate. A first force detector having a formed first electrode and a second electrode formed on the other surface; and the first piezoelectric substrate is extended from the first force detector, and the first electrode is extended. A semiconductor element connected to the first electrode or the second electrode is provided on one piezoelectric substrate. A rigidity different from the rigidity of the first piezoelectric substrate in which the first force detection unit is formed between one circuit unit, the first force detection unit of the first piezoelectric substrate, and the first circuit unit. An adjusted first stiffness adjusting section, and the second force detecting element is formed on the second piezoelectric substrate, the third electrode formed on one surface of the second piezoelectric substrate, and the other surface. A second force detector having a fourth electrode formed thereon, and the second piezoelectric substrate is extended from the second force detector, and the third electrode or the second electrode is extended on the extended second piezoelectric substrate. The second force detection unit is formed between the second circuit unit provided with the semiconductor element connected to the four electrodes, and the second force detection unit and the second circuit unit of the second piezoelectric substrate. A second stiffness adjusting section adjusted to a stiffness different from the stiffness of the second piezoelectric substrate, and the third force detecting element is A third force detection unit having a third piezoelectric substrate, a fifth electrode formed on one surface of the third piezoelectric substrate, and a sixth electrode formed on the other surface; and from the third force detection unit A third circuit portion in which the third piezoelectric substrate is extended, and a semiconductor element connected to the fifth electrode or the sixth electrode is provided on the extended third piezoelectric substrate; A third stiffness adjusting unit adjusted to a stiffness different from the stiffness of the third piezoelectric substrate on which the third force sensing portion is formed between the third force sensing portion of the substrate and the third circuit portion; , Is provided.

According to this configuration, the force detection module includes the first force detection element, the second force detection element, and the third force detection element that detect forces in three orthogonal directions. In addition, a stiffness adjustment unit that is adjusted to a stiffness different from the stiffness of the piezoelectric substrate on which the force detection unit is formed is provided between the force detection unit and the circuit unit of the piezoelectric substrate of each force detection element. As the rigidity adjusting section, a rigidity adjusting section having a lower rigidity than the piezoelectric substrate of the force detecting section or a rigidity adjusting section having a high rigidity is provided.
The external force applied to the force detection unit applies stress to the piezoelectric substrate, and this stress is also transmitted from the piezoelectric substrate of the force detection unit to the circuit unit. At this time, when the rigidity of the rigidity adjusting unit is lower than that of the piezoelectric substrate, the piezoelectric substrate is deformed by the rigidity adjusting unit to relieve the stress. For this reason, this stress is not transmitted to the circuit portion, the channel region of the semiconductor element formed in the circuit portion is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
In addition, when the rigidity of the rigidity adjusting unit is higher than that of the piezoelectric substrate, the stress that attempts to deform the piezoelectric substrate by the rigidity adjusting unit can be restricted, and the deformation of the piezoelectric substrate of the circuit unit is suppressed. For this reason, this stress is not transmitted to the circuit portion, the channel region of the semiconductor element formed in the circuit portion is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
As described above, since the force detection module of this application example can suppress fluctuations in the threshold voltage of the semiconductor element, the force detection unit and the circuit unit are integrally formed on the piezoelectric substrate that has been difficult to put into practical use. Therefore, it is possible to reduce the size of the force detection module.

  Application Example 13 In the force detection module according to the application example, the first piezoelectric substrate, the second piezoelectric substrate, and the third piezoelectric substrate are formed of a quartz substrate, and the first piezoelectric substrate and the third piezoelectric substrate are formed. Is a Y-cut quartz substrate, and the second piezoelectric substrate is preferably an X-cut quartz substrate.

According to this configuration, crystal substrates are used as the first, second, and third piezoelectric substrates, and the first and third piezoelectric substrates are Y-cut crystal substrates, and are resistant to forces in the x-axis or y-axis direction. Can be detected. The second piezoelectric substrate is an X-cut quartz substrate and can be detected with respect to a force in the z-axis direction. Quartz is a long-term stable material and can constitute a force detection module with excellent accuracy and reliability.
Thus, by selecting the crystal cutting direction as the quartz substrate, it is possible to detect forces corresponding to three orthogonal axes.

  [Application Example 14] A force detection unit according to this application example is a force detection unit using four force detection modules described above, and includes four force detection units between a first pressurizing plate and a second pressurizing plate. The detection module is sandwiched by applying pressure, and the force detection module is disposed on a line passing through a center of the first pressurizing plate or the second pressurizing plate and orthogonal to each other.

  According to this configuration, it is possible to detect forces from all three-dimensional directions (forces in six axes). In particular, by using a quartz material having a characteristic of high rigidity for the detection unit, it is possible to provide a force detection unit capable of stably detecting a highly accurate force even with a small amount of displacement.

  Application Example 15 A robot according to this application example is a robot including a main body portion, an arm portion connected to the main body portion, and a hand portion connected to the arm portion, and the arm portion and the hand A force detection module in which the piezoelectric substrate is laminated, and the z-axis direction when the lamination direction of the piezoelectric substrates is the z-axis direction. A first force detection element for detecting a force in the x-axis direction and a force in the z-axis direction, where the direction orthogonal to the x-axis direction is the x-axis direction, and the direction orthogonal to the x-axis direction is the y-axis direction. A second force detecting element for detecting the force and a third force detecting element for detecting the force in the y-axis direction, wherein the first force detecting element is one of the first piezoelectric substrate and the first piezoelectric substrate. Formed on the surface of the first electrode and the other surface A first force detection unit having two electrodes, and the first piezoelectric substrate extends from the first force detection unit, and the first electrode or the second electrode is formed on the extended first piezoelectric substrate. A first circuit portion to be connected, and the first circuit portion is provided with a semiconductor element having a gate electrode, and the first force detection portion of the first piezoelectric substrate and the first circuit portion A first stiffness adjusting unit adjusted to a stiffness different from the stiffness of the first piezoelectric substrate on which the first force detecting unit is formed is provided, and the second force detecting element is connected to the second piezoelectric substrate. A second force detector having a third electrode formed on one surface of the second piezoelectric substrate and a fourth electrode formed on the other surface, and the second piezoelectric substrate from the second force detector And the second electrode connected to the third electrode or the fourth electrode on the extended second piezoelectric substrate. A semiconductor element having a gate electrode is provided in the second circuit unit, and the second circuit unit is provided between the second force detection unit and the second circuit unit of the second piezoelectric substrate. A second stiffness adjusting unit adjusted to a stiffness different from the stiffness of the second piezoelectric substrate on which a two-force detecting unit is formed is provided, and the third force sensing element includes a third piezoelectric substrate and the third piezoelectric substrate. A third force detector having a fifth electrode formed on one surface of the substrate and a sixth electrode formed on the other surface, and the third piezoelectric substrate extends from the third force detector, A third circuit portion connected to the fifth electrode or the sixth electrode on the extended third piezoelectric substrate, and a semiconductor element having a gate electrode is provided in the third circuit portion. The third force detection unit is formed between the third force detection unit and the third circuit unit of the third piezoelectric substrate. A third stiffness adjusting unit adjusted to a stiffness different from the stiffness of the third piezoelectric substrate is provided.

According to this configuration, the force detection module is provided at the connection portion between the arm portion and the hand portion. The force detection module includes a first force detection element, a second force detection element, and a third force detection element that detect forces in three orthogonal directions. Each force detection element is provided with a stiffness adjustment unit adjusted to a stiffness different from that of the piezoelectric substrate on which the force detection unit is formed, between the force detection unit and the circuit unit of the piezoelectric substrate of each force detection element. ing. As the rigidity adjusting section, a rigidity adjusting section having a lower rigidity than the piezoelectric substrate of the force detecting section or a rigidity adjusting section having a high rigidity is provided.
The external force applied to the force detection unit applies stress to the piezoelectric substrate, and this stress is also transmitted from the piezoelectric substrate of the force detection unit to the circuit unit. At this time, when the rigidity of the rigidity adjusting unit is lower than that of the piezoelectric substrate, the piezoelectric substrate is deformed by the rigidity adjusting unit to relieve the stress. For this reason, this stress is not transmitted to the circuit portion, the channel region of the semiconductor element formed in the circuit portion is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
In addition, when the rigidity of the rigidity adjusting unit is higher than that of the piezoelectric substrate, the stress that attempts to deform the piezoelectric substrate by the rigidity adjusting unit can be restricted, and the deformation of the piezoelectric substrate of the circuit unit is suppressed. For this reason, this stress is not transmitted to the circuit portion, the channel region of the semiconductor element formed in the circuit portion is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
Since the fluctuation of the threshold voltage of the semiconductor element can be suppressed, the force detection unit and the circuit unit can be integrally formed on a piezoelectric substrate that has been difficult to put into practical use, and the force detection module can be reduced in size. It becomes possible to plan.
In this way, the force detection module is miniaturized and can be easily mounted on the connecting portion between the arm portion and the hand portion. It is possible to detect the contact with the object and the contact force with the object with high accuracy. And the robot which performs a safe and detailed operation | work using this detection data can be provided.

  Application Example 16 In the robot according to the application example, the first piezoelectric substrate, the second piezoelectric substrate, and the third piezoelectric substrate are formed of a quartz substrate, and the first piezoelectric substrate and the third piezoelectric substrate are Y It is a cut quartz substrate, and the second piezoelectric substrate is preferably an X cut quartz substrate.

According to this configuration, crystal substrates are used as the first, second, and third piezoelectric substrates, and the first and third piezoelectric substrates are Y-cut crystal substrates, and are resistant to forces in the x-axis or y-axis direction. Can be detected. The second piezoelectric substrate is an X-cut quartz substrate and can be detected with respect to a force in the z-axis direction. Quartz is a long-term stable material and can constitute a force detection module with excellent accuracy and reliability.
From this, it is possible to accurately detect the detection of contact with obstacles, detection of contact force with the target, etc. that occur during a specified operation on the arm or hand unit that operates, and a highly reliable robot Can be provided.

  [Application Example 17] A force detection element according to this application example includes a piezoelectric substrate, a first electrode formed on one surface of the piezoelectric substrate, and a second electrode formed on the other surface. An applied force detector, the piezoelectric substrate extending from the force detector, a MOS semiconductor element connected to the first electrode or the second electrode on the extended piezoelectric substrate, and the piezoelectric substrate A stiffness adjusting unit adjusted to a stiffness different from the stiffness of the piezoelectric substrate on which the force sensing portion is formed, between the force sensing portion and the MOS type semiconductor element. .

According to this configuration, the rigidity adjusting unit adjusted to a rigidity different from the rigidity of the piezoelectric substrate of the force detecting unit is provided between the force detecting unit formed on the piezoelectric substrate and the MOS type semiconductor element. As the rigidity adjusting section, a rigidity adjusting section having a lower rigidity than the piezoelectric substrate of the force detecting section or a rigidity adjusting section having a high rigidity is provided.
The external force applied to the force detection unit applies stress to the piezoelectric substrate, and this stress is also transmitted from the piezoelectric substrate of the force detection unit to the circuit unit. At this time, if the rigidity of the rigidity adjusting unit is lower than the piezoelectric substrate of the force detecting unit, the piezoelectric substrate is deformed by the rigidity adjusting unit to relieve the stress. For this reason, this stress is not transmitted to the MOS type semiconductor element, and the channel region formed in the MOS type semiconductor element is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
Further, when the rigidity of the rigidity adjusting unit is higher than that of the piezoelectric substrate of the force detecting unit, the rigidity adjusting unit can regulate the stress for deforming the piezoelectric substrate, so that the piezoelectric substrate on which the MOS type semiconductor element is formed can be regulated. Suppress deformation. For this reason, this stress is not transmitted to the MOS type semiconductor element, and the channel region formed in the MOS type semiconductor element is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region can be suppressed.
As described above, since the force detection element of this application example can suppress fluctuations in the threshold voltage of the semiconductor element, the force detection unit and the MOS type semiconductor element are integrated on a piezoelectric substrate that has been difficult to put into practical use. It is possible to reduce the size of the force detection element.

The schematic perspective view which shows the structure of the force detection element of 1st Embodiment. The schematic perspective view which showed the structure of the force detection element of 1st Embodiment, and looked at FIG. 1 from the back surface. The schematic plan view which shows the structure of the signal extraction part in 1st Embodiment. FIG. 3 is a schematic partial cross-sectional view illustrating a configuration of a signal extraction unit according to the first embodiment. The schematic plan view explaining the positional relationship of the gate electrode and back gate electrode of the circuit part in 1st Embodiment. FIG. 6 is a schematic partial cross-sectional view showing another structure of the circuit unit in the first embodiment. FIG. 6 is a schematic partial cross-sectional view showing another structure of the circuit unit in the first embodiment. The schematic plan view which shows the modification in 1st Embodiment and shows arrangement | positioning of a rigidity adjustment part. The schematic plan view which shows the modification in 1st Embodiment and shows arrangement | positioning of a rigidity adjustment part. The schematic sectional drawing which shows the modification in 1st Embodiment, and shows the cross-sectional shape of a rigidity adjustment part. The schematic sectional drawing which shows the modification in 1st Embodiment, and shows the cross-sectional shape of a rigidity adjustment part. The schematic sectional drawing which shows the modification in 1st Embodiment, and shows the cross-sectional shape of a rigidity adjustment part. The schematic plan view which shows the modification in 1st Embodiment. The perspective view which shows schematic structure of the force detection module in 2nd Embodiment. The disassembled perspective view which shows the structure of the force detection module in 2nd Embodiment. The schematic fragmentary sectional view which shows the structure of the circuit part and rigidity adjustment part in 2nd Embodiment. Sectional drawing explaining the crystal orientation of each quartz substrate of the force detection module in 2nd Embodiment. The structure of the force detection module in 3rd Embodiment is shown, (a) is a conceptual perspective view, (b) is a schematic plan view. The perspective view which shows schematic structure of the robot in 4th Embodiment. The schematic diagram which shows schematic structure of the double-arm robot in 5th Embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In the drawings used for the following description, the ratio of dimensions of each member is appropriately changed so that each member has a recognizable size.
(First embodiment)

FIG. 1 is a schematic perspective view showing the configuration of the force detection element of this embodiment, and FIG. 2 is a schematic perspective view of the force detection element of FIG. FIG. 3 is a schematic plan view showing a signal extraction portion of the force detection element. FIG. 4 is a schematic partial sectional view taken along the line AA in FIG.
As shown in FIGS. 1 and 2, the force detection element 1 uses a quartz substrate 6 that is stable for a long time as a piezoelectric substrate, and includes a force detection unit 10, a signal extraction unit 20, and a ground connection unit 40.
The quartz substrate 6 includes projecting portions 6b and 6c extending from two of the square-shaped portion 6a and the four sides of the square, and these are integrally formed.
The force detection unit 10 includes a square-shaped portion 6a of the quartz substrate 6, a first electrode 11 formed on one surface of the square-shaped portion 6a, and a second electrode 12 formed on the other surface of the square-shaped portion 6a. And having. The first electrode 11 and the second electrode 12 are disposed to face each other with the crystal substrate 6 interposed therebetween.
In this embodiment, the quartz substrate 6 is an X-cut quartz substrate, and is configured so that a force in a direction perpendicular to the plane (surface) of the quartz substrate 6 can be detected.

As shown in FIG. 3 and FIG. 4, a groove portion 27 a as a stiffness adjusting portion and a circuit portion 21 are provided on one surface of the signal lead-out portion 20.
The groove part 27a is provided between the force detection part 10 and the circuit part 21 in a plan view in the thickness direction of the quartz substrate 6, and is arranged so as to be parallel to one side of the square part 6a. Then, the groove 27a is formed by etching from one surface of the quartz substrate 6, and the plate thickness t of the groove 27a is formed to be thinner than the thickness T of the quartz substrate. By forming the groove 27a in this way, it is possible to form a stiffness adjusting unit having a lower stiffness than that of the quartz crystal substrate 6 on which the force detecting unit is formed.

The input side of the circuit unit 21 is connected to the first electrode 11 of the force detection unit 10 by the connection wiring 23, and the output side is connected to a connection pad 22 that performs connection with the outside.
As shown in FIG. 4, the circuit unit 21 includes a MOS (Metal Oxide Semiconductor) type semiconductor element 30. A plurality of MOS semiconductor elements 30 are formed in the circuit unit 21 to constitute the circuit unit 21.
A back gate electrode 25 that is in contact with the surface of the crystal substrate 6 is formed at the protrusion 6 b of the crystal substrate 6 that constitutes the signal lead-out portion 20. An insulating film 26 is provided on the back gate electrode 25.
A polysilicon TFT (Thin Film Transistor) is formed on the insulating film 26 as the MOS semiconductor element 30. The MOS semiconductor element 30 has a gate electrode 34, a source electrode 35, and a drain electrode 36, and these electrodes are wired as desired in the insulating layer 37. As described above, since the MOS semiconductor element 30 includes the polysilicon TFT, an analog circuit such as an amplifier and an AD converter, and a digital circuit such as a signal processing circuit can be integrated in the circuit unit 21.
The MOS semiconductor element 30 may be formed of an oxide semiconductor material.

Further, as shown in FIG. 3, when the length of the groove portion 27a facing the force detection unit 10 is L1, and the length of the circuit unit 21 facing the force detection unit 10 is L2, the relationship is L1> L2. Is set. The entire length L2 of the circuit unit 21 facing the force detection unit 10 is opposed to the length L1 of the groove.
Further, the plate thickness t of the groove 27a is approximately t = T / 2, where T is the thickness of the quartz substrate. Further, the width W of the groove 27a is about W = L1 / 10.

Next, the positional relationship between the gate electrode 34 and the back gate electrode 25 will be described.
FIG. 5 schematically shows a state in plan view of the MOS semiconductor element 30 of the circuit unit 21 as viewed from the thickness direction of the quartz substrate 6.
The back gate electrode 25 is formed at an overlapping position including the gate electrode 34 in plan view. In the present embodiment, the back gate electrode 25 is formed at the overlapping position including the gate electrode 34, the source electrode 35, and the drain electrode 36, but it is sufficient that at least the gate electrode 34 is formed to overlap.
The back gate electrode 25 is connected to the ground by a wiring 38 (see FIG. 4).

In this embodiment, the quartz substrate 6 and the back gate electrode 25 are in direct contact with each other. However, as shown in FIG. 6, the insulating layer 27 is interposed between the quartz substrate 6 and the back gate electrode 25. There may be.
Further, in the present embodiment, the back gate electrode 25 is connected to the ground. However, as shown in FIG. 7, the back gate electrode 25 may be connected to the constant voltage power supply 28 to hold a constant voltage.

Returning to FIG. 2, on the other surface of the quartz substrate 6, a ground electrode 41 extending from the second electrode 12 is formed on the protruding portion 6 c of the quartz substrate 6, and the ground connection portion 40 is configured. The ground electrode 41 is connected to the ground.
In addition, as a material of the various electrodes from the above, simple substance, such as gold | metal | money, chromium, titanium, aluminum, copper, or the alloy which has these materials as a main component can be used.

When the force detection element 1 configured as described above is used to detect a force such as an external force, a pressure (about 10 kN) is applied to the force detection unit 10 in the thickness direction of the quartz substrate 6.
Due to this pressurization, a charge is induced in the crystal substrate 6 of the force detection unit 10. Further, when an external force is applied in the thickness direction of the quartz substrate 6, a charge is further induced. Therefore, it is possible to detect the external force by capturing the change.
Here, when an external force is applied to the force detection unit 10, a stress is applied to the quartz substrate 6, and the stress propagates to the protruding portion 6 b and a force that deforms the protruding portion 6 b acts. At this time, the stress propagating to the protruding portion 6b is deformed in the groove portion 27a having low rigidity and the propagated stress is relaxed, and this stress is not transmitted from the groove portion 27a to the distal end direction of the protruding portion 6b. For this reason, since the stress is not transmitted to the circuit unit 21 and the circuit unit 21 is not deformed, the channel region of the semiconductor element formed in the circuit unit 21 is not deformed, and the threshold value caused by the deformation of the channel region Voltage fluctuation can be suppressed.

  Further, when an external force is applied to the piezoelectric substrate of the force detection element unit, most of the stress caused by the external force is alleviated by the rigidity adjusting unit of the present invention, and a part of the stress is applied to the piezoelectric substrate of the circuit unit. is there. At that time, charges may be induced on the surface of the piezoelectric substrate, which is also a piezoelectric transducer that detects high-sensitivity and minute stress, but the electric field due to the induced charges can be shielded at the back gate electrode, and the threshold voltage of the semiconductor element Variations can be suppressed. In this case, the channel region of the semiconductor element may be slightly deformed together with the piezoelectric substrate, but the resulting change in threshold voltage is almost negligible. Therefore, the rigidity adjustment unit and the back gate electrode of the present invention allow the semiconductor element to be changed. The fluctuation of the threshold voltage can be suppressed.

As described above, in the force detection element 1 of the present embodiment, the groove 27a having a lower rigidity than the rigidity of the crystal substrate 6 on which the force detection unit 10 is formed between the force detection unit 10 of the crystal substrate 6 and the circuit unit 21. Is provided.
The external force applied to the force detector 10 propagates as stress to the protrusion 6b, but the quartz substrate 6 is deformed by the groove 27a to relieve the stress. For this reason, this stress is not transmitted to the circuit unit 21, and the channel region of the MOS semiconductor element 30 formed in the circuit unit 21 is not deformed, and the fluctuation of the threshold voltage due to the deformation of the channel region is suppressed. Can do.
And since the fluctuation | variation of the threshold voltage of MOS type | mold semiconductor element 30 can be suppressed, the force detection part 10 and the circuit part 21 can be integrally formed on the quartz substrate 6 conventionally difficult to put into practical use, The force detection element 1 can be downsized.
Further, the groove 27 a faces the force detection unit 10 and faces the circuit unit 21. And the circuit part 21 is arrange | positioned so that the whole length which opposes the force detection part 10 of the circuit part 21 may oppose the groove part 27a. That is, the groove portion 27 a is formed between the circuit portion 21 and the force detection portion 10 so as to cover the length facing the force detection portion 10.
For this reason, the stress transmitted from the force detection unit 10 can be relaxed or regulated by the groove 27 a, and the stress is not transmitted to the circuit unit 21.

In addition, since the force detection element of this embodiment can detect external force, it can also be utilized for a pressure sensor, an engine pressure gauge, a weight scale, etc.
(Modification)

Next, modified examples such as the shape and arrangement of the groove portion as the rigidity adjusting portion in the first embodiment will be described. Hereinafter, description will be mainly given of the groove portion, and detailed description of the same configuration as that of the first embodiment will be omitted.
8 and 9 are schematic plan views showing a modification of the first embodiment and showing the arrangement of the rigidity adjusting portion.
FIG. 8A shows a modification in which the groove portion in the first embodiment is divided into two at the center portion. In this way, the connection wiring 23 that connects the first electrode 11 of the force detection unit 10 and the circuit unit 21 can be wired between the two groove portions 27a, and can be connected at the shortest distance. For this reason, it is possible to reduce noise on the connection wiring 23. At this time, the length L1 of the groove 27a facing the force detection unit 10 is a length between the outer sides of the two grooves 27a.
8B includes three divided groove portions 27a, and the length L3 facing the force detection portion 10 in the central groove portion is longer than the length L2 where the circuit portion 21 faces the force detection portion 10. Has been. And the groove part 27a is formed in the both sides to the side end of the protrusion part 6b. At this time, the length L1 of the groove portion 27a facing the force detection unit 10 is the length between the outer sides of the three groove portions 27a, and is the same as the width of the protruding portion 6b. In this case, the length L2 of the circuit portion 21 is covered with the central groove portion, and the groove portions on both sides can be formed to further reduce the rigidity, and the stress from the force detection portion 10 can be relieved. it can.
8C, the arrangement of the groove 27a is the same as that in FIG. 8B, but the connection wiring 23 is connected to the first electrode of the force detection unit 10 at two locations through the groove 27a. In this way, the conduction resistance in the connection wiring can be lowered.

In FIG. 9A, the groove 27a is divided and formed by a plurality of square grooves. In this way, the connection wiring 23 can be drawn out from various places, and the degree of freedom in design is improved.
FIG. 9B shows a modification in which the groove portions 27a and 27b are doubled toward the end of the protruding portion 6b. In addition to the arrangement of the groove 27a in FIG. 8A, another groove 27b is provided at the center. In this way, the propagation of stress from the center for passing through the connection wiring 23 can be relaxed by the other groove 27b.

FIG. 10 is a schematic cross-sectional view showing another modification of the first embodiment and showing the cross-sectional shape of the stiffness adjusting portion.
In FIG. 10A, the groove 27 a is formed from both sides of the quartz substrate 6. In the first embodiment, the groove 27a is formed on one side of the quartz substrate, but the groove 27a may be formed from both sides in this way.
FIG. 10B shows a modification in which the groove portion 27a is formed from both surfaces of the quartz substrate 6, and the bottom surface of the groove portion 27a is stepped.
FIG. 10C shows a modified example in which the hole 27c is formed by processing such as etching of the groove 27a.

FIG. 11 is a schematic cross-sectional view showing another modification of the first embodiment and showing a cross-sectional shape of the stiffness adjusting portion. This modification is a modification corresponding to the conflicting problem that the rigidity is lowered by forming the groove and the hole in the quartz substrate and the strength is reduced on the other side.
In FIG. 11 (a), a soft member 27 d is embedded in a groove 27 a formed from one side of the quartz substrate 6, thereby constituting a stiffness adjusting unit 27. The soft member 27d is made of a material having rigidity lower than that of quartz such as silicone.
In FIG. 11 (b), the rigidity adjusting portion 27 is configured by embedding a soft member 27 d in the groove portion 27 a formed from both surfaces of the quartz substrate 6. The soft member 27d is made of a material having rigidity lower than that of quartz, such as silicone, as described above.
In FIG. 11 (c), the stiffness adjusting unit 27 is configured by embedding a soft member 27 d in a hole 27 c formed in the quartz substrate 6. The soft member 27d is made of a material having rigidity lower than that of quartz, such as silicone, as described above.

  As described above, the groove 27a and the hole 27c formed to reduce the rigidity are reinforced by the soft member 27d having a rigidity lower than that of the quartz crystal, thereby ensuring the strength and finely adjusting the rigidity. be able to. Since the material to be reinforced is a soft material, the rigidity is slowly increased with respect to the amount to be embedded, and the adjustment of the rigidity is easy.

FIG. 12 is a schematic cross-sectional view showing another modification of the first embodiment and showing a cross-sectional shape of the rigidity adjusting portion.
In the present modification, the rigidity is increased as the rigidity adjusting portion, and the stress for deforming the quartz substrate is regulated.
As shown in FIG. 12, an additional member 27e for adding thickness to the quartz substrate 6 is fixed on both sides to constitute the stiffness adjusting portion 27. The material of the additional member 27e is preferably higher than the rigidity of the quartz substrate 6, but is not limited to this, and may be a resin such as polyethylene resin or polyimide resin.
As described above, when the rigidity of the rigidity adjusting unit 27 is higher than that of the quartz substrate 6, the rigidity adjusting unit 27 can regulate the stress that causes the quartz substrate 6 to be deformed. Suppress. For this reason, this stress is not transmitted to the circuit portion, and the channel region of the MOS type semiconductor element formed in the circuit portion is not deformed, so that variation in threshold voltage due to deformation of the channel region can be suppressed. .

Moreover, the following modifications can be implemented.
FIG. 13 is a schematic plan view showing a modification of the force detection element.
In this modification, the shape of the quartz substrate is different from that of the force detection element of the first embodiment.
The force detection element 2 includes a quartz substrate 6 and includes a force detection unit 10 and a signal extraction unit 20. The quartz substrate 6 extends in the same width as the force detection unit 10 and is formed in a rectangular shape.
The force detection unit 10 includes a square-shaped first electrode 11 formed on one surface of the quartz substrate 6 and a second electrode 12 formed on the other surface. The first electrode 11 and the second electrode 12 are disposed to face each other with the crystal substrate 6 interposed therebetween.
The quartz substrate 6 is an X-cut quartz substrate, and is configured to detect a force in a direction perpendicular to the plane (surface) of the quartz substrate 6.

On one surface of the signal lead-out part 20, a groove part 27a as a rigidity adjusting part and a circuit part 21 are provided.
The groove 27 a is provided between the force detection unit 10 and the circuit unit 21 in a plan view in the thickness direction of the quartz substrate 6 and is arranged to be parallel to one side of the first electrode 11. The groove 27 a is formed by etching from one surface of the quartz substrate 6.

The input side of the circuit unit 21 is connected to the first electrode 11 of the force detection unit 10 by the connection wiring 23, and the output side is connected to a connection pad 22 that performs connection with the outside.
The circuit unit 21 includes a MOS type semiconductor element as in the first embodiment.
Thus, the shape of the quartz substrate 6 can be changed as appropriate depending on the required size of the force detection unit 10.
In this modification, the first electrode 11 and the second electrode 12 that detect the force of the force detection unit 10 are small in size, and the force detection element 2 can be downsized by such a structure.
(Second Embodiment)

Next, a force detection module that can detect forces in a plurality of directions using a plurality of force detection elements will be described.
The force detection module of this embodiment is a form in which the force detection elements described in the first embodiment are stacked.

  FIG. 14 is a perspective view showing a schematic configuration of the force detection module of the present embodiment. FIG. 15 is an exploded perspective view showing the configuration of the force detection module of the present embodiment. FIG. 16 is a schematic partial sectional view taken along the line BB in FIG. FIG. 17 is a cross-sectional view for explaining the crystal orientation of each quartz substrate of the force detection module in the present embodiment.

As shown in FIGS. 14 and 15, the force detection module 50 is formed by laminating a first force detection element 51, a second force detection element 52, and a third force detection element 53.
Here, for convenience of explanation, orthogonal coordinate axes (x, y, z axes) are defined. When the stacking direction of the detection elements is the z-axis direction, the direction orthogonal to the z-axis direction is the x-axis direction, and the direction orthogonal to the x-axis direction and the z-axis direction is the y-axis direction.
The first force detection element 51 detects a force in the x-axis direction, the second force detection element 52 detects a force in the z-axis direction, and the third force detection element 53 detects a force in the y-axis direction.

The first force detection element 51 includes a first ground electrode 57a, a first crystal substrate 61, a first detection electrode 54, a second crystal substrate 62, and a second ground electrode 57b in order from the stacked upper side to the lower side. doing.
The first crystal substrate 61 includes a first ground connection part 51d that protrudes from one side of the first force detection part 51a.
The second crystal substrate 62 includes a first ground connection part 51c protruding from one side of the first force detection part 51a and a first signal extraction part 51b protruding from the other side. The first signal lead-out part 51b is provided with a first circuit part 60a and a first groove part 78a as a rigidity adjusting part formed between the first force detection part 51a and the first circuit part 60a. Yes.

The second force detection element 52 includes, in order from the upper side to the lower side, the second ground electrode 57b, the third crystal substrate 63, the second detection electrode 55, and the fourth crystal that are shared with the first force detection element 51. A substrate 64 and a third ground electrode 57c are provided.
The third crystal substrate 63 includes a second ground connection portion 52d that protrudes from one side of the second force detection portion 52a, and a laminated support portion 52e that supports the first signal extraction portion 51b of the second crystal substrate 62.
The fourth crystal substrate 64 includes a second ground connection portion 52c that protrudes from one side of the second force detection portion 52a, a stacked support portion 52e that supports the first signal extraction portion 51b of the second crystal substrate 62, and a second ground. A second signal extraction portion 52b protruding from the side facing the connection portion 52c is provided. The second signal lead-out part 52b is provided with a second circuit part 60b and a second groove part 78b as a rigidity adjusting part formed between the second force detection part 52a and the second circuit part 60b. Yes.

The third force detection element 53 includes, in order from the upper side to the lower side, the third ground electrode 57c, the fifth crystal substrate 65, the third detection electrode 56, and the sixth crystal that are shared with the second force detection element 52. A substrate 66 and a fourth ground electrode 57d are provided.
The fifth crystal substrate 65 includes a third ground connection portion 53d that protrudes from one side of the third force detection portion 53a, a stacked support portion 53e that supports the first signal lead portion 51b of the second crystal substrate 62, and a fourth crystal. And a stacking support portion 53f that supports the second signal extraction portion 52b of the substrate 64.
The sixth crystal substrate 66 includes a third ground connection portion 53c that protrudes from one side of the third force detection portion 53a, a stacked support portion 53e that supports the first signal extraction portion 51b of the second crystal substrate 62, and a fourth crystal. A lamination support part 53f that supports the second signal extraction part 52b of the substrate 64 and a third signal extraction part 53b that protrudes from the side facing the lamination support part 53e are provided. The third signal lead-out part 53b is provided with a third circuit part 60c and a third groove part 78c as a rigidity adjusting part formed between the third force detection part 53a and the third circuit part 60c. Yes.

The first circuit unit 60a, the second circuit unit 60b, and the third circuit unit 60c have MOS type semiconductor elements as in the first embodiment, and directly below the crystal substrate under the gate electrode of the MOS type semiconductor element. Alternatively, a back gate electrode in contact with the insulating layer is provided, and the back gate electrode is connected to the ground.
About these structures, the 1st circuit part 60a, the 2nd circuit part 60b, and the 3rd circuit part 60c are the same structures, and here demonstrates the 1st circuit part 60a as an example.
As shown in FIG. 16, the first circuit section 60a has a MOS semiconductor element 73. A plurality of MOS type semiconductor elements 73 are formed in the first circuit portion 60a to constitute the first circuit portion 60a.
In the second crystal substrate 62 constituting the first signal lead-out portion 51b, a back gate electrode 70 that is in contact with the surface of the second crystal substrate 62 directly or through an insulating layer is formed. An insulating film 71 is provided on the back gate electrode 70.
On the insulating film 71, a polysilicon TFT is formed as the MOS type semiconductor element 73. The MOS semiconductor element 73 has a gate electrode 74, a source electrode 75, and a drain electrode 76, and these electrodes are wired as desired in the insulating layer 72. Thus, since the MOS type semiconductor element 73 has the polysilicon TFT, digital circuits such as analog circuits such as amplifiers and AD converters and signal processing circuits can be integrated in the first circuit section 60a.
Although not shown, the back gate electrode 70 is formed at an overlapping position including the gate electrode 74 in plan view as in the first embodiment, and is connected to the ground.

Thus, in the state where the respective components are stacked, the force detection module 50 exposes the first signal lead portion 51b, the second signal lead portion 52b, and the third signal lead portion 53b on the upper surface as shown in FIG. To be arranged. The first signal extraction unit 51b, the second signal extraction unit 52b, and the third signal extraction unit 53b include the first circuit unit 60a, the second circuit unit 60b, the third circuit unit 60c, and the first connection pads 59a, respectively. A second connection pad 59b and a third connection pad 59c are provided.
Further, the third crystal substrate 63 to the sixth crystal substrate 66 located below the first signal extraction portion 51b are formed with support portions for supporting the first signal extraction portion 51b, and are integrated to the bottom surface of the force detection module 50. It is formed to become. Similarly, on the fifth crystal substrate 65 and the sixth crystal substrate 66 located below the second signal lead-out portion 52b, support portions for supporting the second signal lead-out portion 52b are formed, and the bottom of the force detection module 50 is integrated. It is formed to become.

The first ground connection portions 51c and 51d, the second ground connection portions 52c and 52d, and the third ground connection portions 53c and 53d are formed so as to be integrated from the top surface to the bottom surface of the force detection module 50, and grounded on the side surface thereof. A connection electrode 58 is formed, and conduction between the ground electrodes is achieved.
In FIG. 13, for convenience of explanation, the first detection electrode 54, the second detection electrode 55, the third detection electrode 56, the first ground electrode 57a, the second ground electrode 57b, the third ground electrode 57c, and the fourth ground electrode. 57d is expressed separately for each quartz substrate, but in actuality, it is formed on one of the quartz substrates in contact with each quartz substrate by a technique such as vapor deposition or sputtering. For this reason, it is only necessary to form electrodes on one of the quartz substrates, and it is not necessary to form electrodes on both substrates.

Next, combinations of crystal orientations in each quartz substrate will be described.
FIG. 15 is a cross-sectional view for explaining the crystal orientation of each quartz substrate of the force detection module of this embodiment.
In the first force detection element 51, the first crystal substrate 61 and the second crystal substrate 62 are formed of a Y-cut crystal substrate, and the X direction, which is a crystal orientation for generating a piezoelectric phenomenon, is the first crystal substrate 61 and the second crystal substrate. The crystal orientation is perpendicular to the normal of 62. The first crystal substrate 61 and the second crystal substrate 62 are arranged so that the X directions are opposite to each other.

  In the second force detection element 52, the third crystal substrate 63 and the fourth crystal substrate 64 are formed of an X-cut crystal substrate, and the X direction is parallel to the normal line of the third crystal substrate 63 and the fourth crystal substrate 64. The crystal orientation is as follows. The third crystal substrate 63 and the fourth crystal substrate 64 are arranged so that the X directions are opposite to each other.

  In the third force detection element 53, the fifth crystal substrate 65 and the sixth crystal substrate 66 are formed of a Y-cut crystal substrate, and the crystal whose X direction is perpendicular to the normal line of the fifth crystal substrate 65 and the sixth crystal substrate 66. Has an orientation. The fifth crystal substrate 65 and the sixth crystal substrate 66 are arranged so that the X directions are opposite to each other. Further, the first crystal substrate 61 and the second crystal substrate 62 in the first force detection element 51 are arranged in a direction orthogonal to the X direction.

When the force detection module 50 is used to detect a force such as an external force, a pressure (about 10 kN) is applied using the pressing member 68 in the stacking direction of each force detection element of the force detection module 50.
When a compressive force or a tensile force is applied in a direction parallel to the z-axis, the third crystal substrate 63 and the fourth crystal substrate 64 of the second force detection element 52 receive a compressive force or a tensile force from the z direction of the crystal. As a result, charge is induced as a difference from the pressurized application state, and charge (Fz signal) is output to the second detection electrode 55.
In addition, when a force deviating in a direction parallel to the x-axis is applied, the first crystal substrate 61 and the second crystal substrate 62 of the first force detection element 51 receive a force (shearing force) from the X direction of the crystal due to the piezoelectric phenomenon. Charge is induced, and charge (Fx signal) is output to the first detection electrode 54.
When a force deviating in a direction parallel to the y-axis is applied, the fifth crystal substrate 65 and the sixth crystal substrate 66 of the third force detection element 53 receive a force (shearing force) from the X direction of the crystal, and electric charges are generated by the piezoelectric phenomenon. The charge (Fy signal) is output to the third detection electrode 56 by being induced.
Further, when a force deviating in a direction parallel to the z axis is applied, the third crystal substrate 63 and the fourth crystal substrate 64 of the second force detection element 52 receive a compressive force from the X direction of the crystal, so that the charge changes due to the piezoelectric phenomenon. As a result, the magnitude of the charge (Fz signal) output to the second detection electrode 55 changes.
The induced charge is integrated by the first circuit unit 60a, the second circuit unit 60b, and the third circuit unit 60c (see FIG. 13), converted into a voltage, and then desired by an AD converter, an arithmetic circuit, or the like. Output as a signal.

  Here, when a force is applied to each of the force detection elements 51, 52, and 53, a stress is generated in each of the quartz substrates 61 to 66, and the stress is also propagated to each of the signal extraction portions 51b, 52b, and 53b that do not receive a direct force. . Due to this stress, a force for deforming each of the signal lead portions 51b, 52b, and 53b works. At this time, the stress propagating to each of the signal lead portions 51b, 52b, 53b is relieved of the stress propagating by being deformed in each of the groove portions 78a, 78b, 78c having low rigidity. For this reason, the stress is not transmitted from the groove portions 78a, 78b, 78c to the leading ends of the signal lead portions 51b, 52b, 53b. For this reason, stress is not transmitted to each circuit part 60a, 60b, 60c, and each circuit part 60a, 60b, 60c is not deformed. And the channel region of the semiconductor element formed in each circuit part 60a, 60b, 60c is not deformed, and the variation of the threshold voltage due to the deformation of the channel region can be suppressed.

Further, when an external force or the like is applied to the piezoelectric substrate of the force detection element unit, most of the stress caused by the external force is alleviated by the rigidity adjusting unit of the present invention, but a part of the stress is applied to the piezoelectric substrate of the first circuit unit 60a. There is also a case to join. At that time, charges may be induced on the surface of the piezoelectric substrate, which is also a piezoelectric transducer that detects high-sensitivity and minute stresses. However, the electric field due to the induced charges can be shielded at the back gate electrode, and the threshold voltage of the semiconductor element is reduced. Variations can be suppressed. In this case, the channel region of the semiconductor element may be slightly deformed together with the piezoelectric substrate, but the resulting change in threshold voltage is almost negligible. Therefore, the rigidity adjustment unit and the back gate electrode of the present invention allow the semiconductor element to be changed. The threshold voltage fluctuation can be suppressed more completely.
Similarly, in the second circuit portion 60b and the third circuit portion 60c, the back gate electrode is connected to the ground, so that the electric field of the induced charge can be shielded. For this reason, since the electric field is not affected by the gate electrode of the MOS type semiconductor device formed above the back gate electrode, the fluctuation of the threshold voltage of the MOS type semiconductor device due to the charge induced in the quartz substrate is suppressed. can do.
Therefore, in the force detection module 50 of this embodiment, the charges (detection signals) from the first detection electrode 54, the second detection electrode 55, and the third detection electrode 56 are the first circuit unit 60a, the second circuit unit 60b, It is output to the third circuit unit 60c, and the detection signal is appropriately processed in each circuit, so that the magnitude of the force in each direction can be accurately detected.
In addition, since the fluctuation of the threshold voltage of the MOS type semiconductor element can be suppressed, the force detection unit and the circuit unit can be integrally formed on a quartz substrate that has been difficult to put into practical use. It becomes possible to reduce the size.

In addition, although the quartz substrate was used as the piezoelectric substrate in the force detection element of the first embodiment and the force detection module of the second embodiment, in addition, lead zirconate titanate (PZT) and barium titanate, which are titanate ceramics. (BaTiO ₃ ), lithium niobate (LiNbO ₃ ), zinc oxide (ZnO), lithium tantalate (LiTaO ₃ ), and other piezoelectric substrates can be used. The same effect as the form can be obtained.
(Third embodiment)

Next, a 6-axis force detection module using a plurality of force detection modules will be described.
FIG. 18 shows a configuration of the force detection module of the present embodiment, where (a) is a conceptual perspective view and (b) is a plan view.
The force detection module 80 of the present embodiment has a configuration in which four force detection modules 50 described in the second embodiment are used and sandwiched between the first pressurizing plate 81 and the second pressurizing plate 82. Each force detection module 50 adjusts the tightening amount by fastening means (not shown) for fastening the first pressurizing plate 81 and the second pressurizing plate 82, and applies a predetermined pressurizing force (for example, to the force detecting module 50). About 10 kN).
Each of the first pressurizing plate 81 and the second pressurizing plate 82 is formed in a disk shape in plan view, and four force detection modules 50 are arranged on lines that pass through the center O and are orthogonal to each other.

  The force detection module 80 having such a configuration is sandwiched between the first pressurizing plate 81 and the second pressurizing plate 82 in a state where all of the four force detecting modules 50 face in the same direction, and pressurization is applied. . For example, in the force detection module 50, the detection axis of the first force detection element 51 (see FIG. 15) is oriented in a direction parallel to Fx, and the detection axis of the second force detection element 52 (see FIG. 15) is parallel to Fz. In the direction, the detection axis of the third force detection element 53 (see FIG. 15) is in a direction parallel to Fy.

  Here, when the relative position of the first pressurizing plate 81 and the second pressurizing plate 82 receives a force that deviates in the Fx direction, the force detection module 50 detects the forces of Fx1, Fx2, Fx3, and Fx4, respectively. Moreover, when the relative position of the 1st pressurization plate 81 and the 2nd pressurization plate 82 receives the force which mutually shifts to Fy direction, the force detection module 50 detects the force of Fy1, Fy2, Fy3, and Fy4, respectively. Furthermore, when the relative position of the first pressurizing plate 81 and the second pressurizing plate 82 receives a force that shifts in the Fz direction, the force detection module 50 detects the forces of Fz1, Fz2, Fz3, and Fz4, respectively.

  Therefore, in the force detection module 80, the forces Fx, Fy, Fz orthogonal to each other, and the rotational force Mx having the direction parallel to Fx as the rotational axis, parallel to the rotational force My, Fz having the direction parallel to Fy as the rotational axis. The rotational force Mz having the rotation direction as the rotation axis can be obtained as follows.

Here, a and b are constants. Therefore, the force detection module 80 of the present embodiment can detect forces from all three-dimensional directions (forces in six axes). In particular, by using a quartz material having a characteristic of high rigidity for the detection unit, the force detection module 80 capable of stably detecting a highly accurate force even with a small amount of displacement is obtained.
(Fourth embodiment)

Next, a robot equipped with a force detection module will be described.
FIG. 19 is a perspective view showing a schematic configuration of the robot in the fourth embodiment.
The robot 100 according to the fourth embodiment is equipped with the force detection module 50 or the force detection module 80 described above.
A robot 100 shown in FIG. 19 includes a main body unit 101, an arithmetic control unit 102, an arm unit 110, a robot hand unit 120, and the like. The main body 101 is fixed on, for example, a floor, a wall, a ceiling, or a movable carriage. The arm part 110 is provided so as to be rotatable with respect to the main body part 101, and an actuator (not shown) that generates power for rotating the arm part 110 is provided on the main body part 101. An arithmetic control unit 102 for controlling is provided.

  The arm unit 110 includes a first frame 111, a second frame 112, a third frame 113, a fourth frame 114, and a fifth frame 115. The first frame 111 is connected to the main body 101 via a rotary bending shaft so as to be rotatable or bendable. The second frame 112 is connected to the first frame 111 and the third frame 113 via a rotating and bending shaft. The third frame 113 is connected to the second frame 112 and the fourth frame 114 via a rotating and bending shaft. The fourth frame 114 is connected to the third frame 113 and the fifth frame 115 via a rotating and bending shaft. The fifth frame 115 is connected to the fourth frame 114 via a rotating and bending shaft. The arm unit 110 is driven by each frame being rotated or bent in a compound manner around each rotation / bending axis under the control of the control unit.

  A robot hand unit 120 is attached to the tip of the fifth frame 115, and the robot hand 121 capable of grasping an object to be processed by the robot 100 incorporates a motor (not shown) that rotates. It is connected to the fifth frame 115 via the robot hand connection unit 122.

  In addition to the motor, the robot hand connection unit 122 incorporates force detection modules 50 and 80 (not shown) detailed in the second and third embodiments. When the robot hand unit 120 moves to a predetermined operation position under the control of the control unit, the robot 100 detects a contact with an obstacle or a contact with an object by an operation command beyond the predetermined position. 50, 80 can be detected as a force, fed back to the arithmetic control unit 102 of the robot 100, and an avoidance operation can be executed.

By mounting the above-described downsized force detection module on such a robot 100, even when a small force is applied to the robot 100, the force can be detected with high accuracy. The robot 100 can detect a small force with high accuracy, thereby quickly detecting contact with an obstacle and the like, which has been difficult to deal with with conventional position control, such as an obstacle avoidance operation and an object damage avoidance operation. Can be performed easily, and safe and detailed work can be realized.
Note that the present invention is not limited to the robot 100 described above, and can be applied to a robot having a plurality of arm units 110 (double-arm robot).
(Fifth embodiment)

Next, a double-arm robot equipped with a force detection module will be described as a fifth embodiment.
FIG. 20 is a schematic diagram showing a schematic configuration of a double-arm robot.
A robot 200 shown in FIG. 20 includes a main body unit 201, a calculation control unit 202, a body unit 203, a head unit 204, arm units 210a and 210b, robot hand units 220a and 220b, and the like. The main body 201 incorporates a traveling unit 206 and an arithmetic control unit 202 that controls an actuator in order to freely travel the robot 200. The arm portions 210a and 210b are provided so as to be rotatable with respect to the body portion 203, and the body portion 203 is an actuator (not shown) that generates power for rotating the arm portions 210a and 210b. Is built-in.

Since the arm portions 210a and 210b and the robot hand portions 220a and 220b have the same configuration, the arm portion 210a and the robot hand portion 220a on one side will be described as a representative.
The arm part 210a includes a first frame 211a and a second frame 212a. The first frame 211a is connected to the body portion 203 via a rotating and bending shaft so as to be rotatable or bendable. The second frame 212a is connected to the first frame 211a and the robot hand unit 220a via a rotating / bending axis. The arm unit 210a is driven by each frame being rotated or bent in a compound manner around each rotation / bending axis under the control of the control unit.

  The second frame 212a has a robot hand portion 220a attached to the opposite end connected to the first frame 211a. A robot hand 221a capable of grasping an object to be processed by the robot 200 is connected to the second frame 212a via a robot hand connecting part 222a containing a motor (not shown) that rotates.

In addition to the motor, the robot hand connector 222a incorporates the force detection modules 50 and 80 (not shown) detailed in the second and third embodiments. When the robot hand unit 220a moves to a predetermined operation position under the control of the control unit, the robot 200 detects a force on an obstacle or contact with an object by an operation command exceeding the predetermined position. It can be detected as a force by the modules 50 and 80, and can be fed back to the arithmetic control unit 202 of the robot 200 to execute an avoidance operation. In addition, the robot 200 includes a camera 205 on the head 204. For example, the robot 200 processes the obstacle imaged by the camera 205 and the force received when the obstacle detected by the force detection modules 50 and 80 is contacted by the arithmetic control unit 202, so that the obstacle is detected. It is possible to estimate the size, hardness, position, etc., and perform an operation to avoid a collision in advance.
The configuration of the arm unit 210b and the robot hand unit 220b is the same as that of the arm unit 210a and the robot hand unit 220a described above.

  By mounting the above-described downsized force detection module on such a robot 200, even when a small force is applied to the robot 200, the force can be detected with high accuracy. The robot 200 can detect a small force with high accuracy, thereby quickly detecting contact with an obstacle and the like, which has been difficult to deal with by conventional position control, such as an obstacle avoidance operation and an object damage avoidance operation. Can be performed easily, and safe and detailed work can be realized. In addition, the robot 200 can be provided with a plurality of arms (an arm unit and a robot hand unit) to handle a large object that is difficult with one arm.

  The present invention is not limited to the embodiment described above, and the specific structure and procedure for carrying out the present invention can be appropriately changed to other structures and the like as long as the object of the present invention can be achieved. it can. Many modifications can be made by those skilled in the art within the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 1, 2 ... Force detection element, 6 ... Quartz substrate, 6a ... Square-shaped part, 6b ... Projection part, 6c ... Projection part, 10 ... Force detection part, 11 ... 1st electrode, 12 ... 2nd electrode, 20 ... Signal Lead-out part, 21 ... Circuit part, 22 ... Connection pad, 23 ... Connection wiring, 25 ... Back gate electrode, 26 ... Insulating film, 27 ... Rigidity adjustment part, 27a, 27b ... Groove part as rigidity adjustment part, 27c ... Rigidity adjustment 27d ... soft member, 27e ... additional member as rigidity adjusting part, 30 ... MOS type semiconductor element, 34 ... gate electrode, 35 ... source electrode, 36 ... drain electrode, 37 ... insulating layer, 38 ... Wiring, 40 ... ground connection part, 41 ... ground electrode, 50 ... force detection module, 51 ... first force detection element, 51a ... first force detection part, 51b ... first signal extraction part, 51c ... first ground connection part 51d 1st Land connection part 52 ... second force detection element 52a ... second force detection part 52b ... second signal extraction part 52c ... second ground connection part 52d ... second ground connection part 52e ... multilayer support part 53 ... 3rd force detection element, 53a ... 3rd force detection part, 53b ... 3rd signal extraction part, 53c ... 3rd ground connection part, 53d ... 3rd ground connection part, 53e ... Lamination support part, 53f ... Lamination support 54, first detection electrode, 55, second detection electrode, 56, third detection electrode, 57a, first ground electrode, 57b, second ground electrode, 57c, third ground electrode, 57d, fourth ground electrode. 58 ... ground connection electrode, 59a ... first connection pad, 59b ... second connection pad, 59c ... third connection pad, 60a ... first circuit part, 60b ... second circuit part, 60c ... third circuit part, 61 ... first crystal Plate 62 ... Second crystal substrate 63 ... Third crystal substrate 64 ... Fourth crystal substrate 65 ... Fifth crystal substrate 66 ... Sixth crystal substrate 68 ... Pressing member 70 ... Back gate electrode 71 ... Insulating film, 72 ... insulating layer, 73 ... MOS type semiconductor element, 74 ... gate electrode, 75 ... source electrode, 76 ... drain electrode, 78a ... first groove as stiffness adjusting portion, 78b ... second as stiffness adjusting portion Groove part, 78c ... third groove part as rigidity adjusting part, 80 ... force detection module, 81 ... first pressurizing plate, 82 ... second pressurizing plate, 100 ... robot, 101 ... main body part, 102 ... calculation control part, DESCRIPTION OF SYMBOLS 110 ... Arm part, 120 ... Robot hand part, 121 ... Robot hand, 122 ... Robot hand connection part, 200 ... Robot, 201 ... Main part, 202 ... Arithmetic control part, 210a, 210b ... Arm Part, 220a, 220b ... Robot hand part, 221a, 221b ... Robot hand, 222a, 222b ... Robot hand connection part, L1, L3 ... Groove part length, L2 ... Circuit part length, W ... Groove width, T ... Quartz substrate thickness , T: groove thickness.

Claims (17)

A piezoelectric substrate;
A first electrode formed on one surface of the piezoelectric substrate, and a second electrode formed on the other surface, and a force detection unit to which an external force is applied;
A circuit unit in which the piezoelectric substrate is extended from the force detection unit, and a semiconductor element connected to the first electrode or the second electrode is provided on the extended piezoelectric substrate;
A rigidity adjusting unit that is adjusted to a stiffness different from the stiffness of the piezoelectric substrate on which the force detecting unit is formed is provided between the force detecting unit and the circuit unit of the piezoelectric substrate. Force detecting element. The force detection element according to claim 1,
In plan view in the thickness direction of the piezoelectric substrate, the length of the rigidity adjusting unit facing the force detecting unit is longer than the length of the circuit unit facing the force detecting unit. Force detection element. The force detection element according to claim 1 or 2,
A force detecting element, wherein the piezoelectric substrate has a recess as the rigidity adjusting portion. The force detection element according to claim 1 or 2,
A force detecting element, wherein a hole penetrating the piezoelectric substrate is formed as the rigidity adjusting portion. The force detection element according to claim 1 or 2,
A force detection element comprising: a concave portion formed in the piezoelectric substrate as the rigidity adjusting portion; and a soft member having lower rigidity than the piezoelectric substrate embedded in the concave portion. The force detection element according to claim 1 or 2,
A force detection element comprising: a hole formed in the piezoelectric substrate as the rigidity adjusting unit; and a soft member having a rigidity lower than that of the piezoelectric substrate embedded in the hole. The force detection element according to claim 1 or 2,
An additional member that adds thickness to the piezoelectric substrate is provided on the piezoelectric substrate as the rigidity adjusting unit. In the force detection element according to any one of claims 1 to 7,
The semiconductor device is a MOS type semiconductor device and has a polysilicon TFT. In the force detection element according to any one of claims 1 to 7,
The semiconductor element is a MOS type semiconductor element;
The MOS type semiconductor element is made of an oxide-based semiconductor material. The force detection element according to any one of claims 1 to 9,
In the circuit part,
A back gate electrode in contact with the surface of the piezoelectric substrate directly or through an insulating layer;
An insulating film covering the back gate electrode;
The semiconductor element having a gate electrode formed on the insulating film,
In the plan view in the thickness direction of the piezoelectric substrate, the back gate electrode is provided at an overlapping position including the gate electrode,
The force detection element, wherein the back gate electrode is connected to ground. The force detection element according to any one of claims 1 to 9,
In the circuit part,
A back gate electrode in contact with the surface of the piezoelectric substrate directly or through an insulating layer;
An insulating film covering the back gate electrode;
The semiconductor element having a gate electrode formed on the insulating film,
In the plan view in the thickness direction of the piezoelectric substrate, the back gate electrode is provided at an overlapping position including the gate electrode,
The force detection element, wherein the back gate electrode is fixed at a constant potential. A force detection module in which a plurality of piezoelectric substrates are stacked,
When the stacking direction of the piezoelectric substrates is the z-axis direction, when the direction orthogonal to the z-axis direction is the x-axis direction, the z-axis direction and the direction orthogonal to the x-axis direction are the y-axis direction,
A first force detection element for detecting the force in the x-axis direction;
A second force detection element for detecting the force in the z-axis direction;
A third force detection element that detects the force in the y-axis direction,
The first force detection element is
A first piezoelectric substrate;
A first force detector having a first electrode formed on one surface of the first piezoelectric substrate and a second electrode formed on the other surface;
A first circuit in which the first piezoelectric substrate is extended from the first force detection unit, and a semiconductor element connected to the first electrode or the second electrode is provided on the extended first piezoelectric substrate. And
The first piezoelectric substrate is adjusted to have a stiffness different from the stiffness of the first piezoelectric substrate on which the first force detector is formed between the first force detector and the first circuit portion of the first piezoelectric substrate. A rigidity adjusting portion, and
The second force detection element is
A second piezoelectric substrate;
A second force detector having a third electrode formed on one surface of the second piezoelectric substrate and a fourth electrode formed on the other surface;
A second circuit in which the second piezoelectric substrate is extended from the second force detector, and a semiconductor element connected to the third electrode or the fourth electrode is provided on the extended second piezoelectric substrate; And
Second stiffness adjusted to a stiffness different from the stiffness of the second piezoelectric substrate on which the second force detection portion is formed between the second force detection portion and the second circuit portion of the second piezoelectric substrate. A rigidity adjusting portion, and
The third force detection element is
A third piezoelectric substrate;
A third force detector having a fifth electrode formed on one surface of the third piezoelectric substrate and a sixth electrode formed on the other surface;
A third circuit in which the third piezoelectric substrate is extended from the third force detector, and a semiconductor element connected to the fifth electrode or the sixth electrode is provided on the extended third piezoelectric substrate; And
Third stiffness adjusted to a stiffness different from the stiffness of the third piezoelectric substrate on which the third force detection portion is formed between the third force detection portion and the third circuit portion of the third piezoelectric substrate. And a rigidity adjusting section. The force detection module according to claim 12,
The first piezoelectric substrate, the second piezoelectric substrate and the third piezoelectric substrate are formed of a quartz substrate,
The first piezoelectric substrate and the third piezoelectric substrate are Y-cut quartz substrates, and the second piezoelectric substrate is an X-cut quartz substrate. A force detection unit using four force detection modules according to claim 12 or 13,
Four force detection modules are sandwiched between the first pressurizing plate and the second pressurizing plate by applying pressure.
The force detection module is arranged on a line passing through the center of the first pressurizing plate or the second pressurizing plate and orthogonal to each other. The main body,
An arm portion connected to the main body portion;
A hand unit connected to the arm unit,
Having a force detection module at the connecting portion between the arm portion and the hand portion;
The force detection module is a force detection module in which piezoelectric substrates are stacked,
When the stacking direction of the piezoelectric substrates is the z-axis direction, when the direction orthogonal to the z-axis direction is the x-axis direction, the z-axis direction and the direction orthogonal to the x-axis direction are the y-axis direction,
A first force detection element for detecting the force in the x-axis direction;
A second force detection element for detecting the force in the z-axis direction;
A third force detection element that detects the force in the y-axis direction,
The first force detection element is
A first piezoelectric substrate;
A first force detector having a first electrode formed on one surface of the first piezoelectric substrate and a second electrode formed on the other surface;
The first piezoelectric substrate is extended from the first force detection unit, and the first circuit unit connected to the first electrode or the second electrode is provided on the extended first piezoelectric substrate,
The first circuit portion is provided with a semiconductor element having a gate electrode,
The first piezoelectric substrate is adjusted to have a stiffness different from the stiffness of the first piezoelectric substrate on which the first force detector is formed between the first force detector and the first circuit portion of the first piezoelectric substrate. A rigidity adjustment part is provided,
The second force detection element is
A second piezoelectric substrate;
A second force detector having a third electrode formed on one surface of the second piezoelectric substrate and a fourth electrode formed on the other surface;
The second piezoelectric substrate extends from the second force detection unit, and the second circuit unit is connected to the third electrode or the fourth electrode on the extended second piezoelectric substrate,
The second circuit portion is provided with a semiconductor element having a gate electrode,
Second stiffness adjusted to a stiffness different from the stiffness of the second piezoelectric substrate on which the second force detection portion is formed between the second force detection portion and the second circuit portion of the second piezoelectric substrate. A rigidity adjustment part is provided,
The third force detection element is
A third piezoelectric substrate;
A third force detector having a fifth electrode formed on one surface of the third piezoelectric substrate and a sixth electrode formed on the other surface;
The third piezoelectric substrate extends from the third force detection unit, and the third circuit unit is connected to the fifth electrode or the sixth electrode on the extended third piezoelectric substrate,
The third circuit portion is provided with a semiconductor element having a gate electrode,
Third stiffness adjusted to a stiffness different from the stiffness of the third piezoelectric substrate on which the third force detection portion is formed between the third force detection portion and the third circuit portion of the third piezoelectric substrate. A robot characterized by a rigidity adjustment unit. The robot according to claim 15, wherein
The first piezoelectric substrate, the second piezoelectric substrate and the third piezoelectric substrate are formed of a quartz substrate,
The first piezoelectric substrate and the third piezoelectric substrate are Y-cut quartz substrates, and the second piezoelectric substrate is an X-cut quartz substrate. A piezoelectric substrate;
A first electrode formed on one surface of the piezoelectric substrate, and a second electrode formed on the other surface, and a force detection unit to which an external force is applied;
The piezoelectric substrate is extended from the force detection unit, and the MOS type semiconductor element connected to the first electrode or the second electrode on the extended piezoelectric substrate;
A stiffness adjusting unit that is adjusted to a stiffness different from the stiffness of the piezoelectric substrate on which the force sensing portion is formed, between the force sensing portion of the piezoelectric substrate and the MOS type semiconductor element. A characteristic force detection element.

Images