JPH10132668A - Sensor utilizing change in capacitance, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sensor from receiving physical damage easily when an excessive outer force is applied. SOLUTION: A doughnut shaped groove is dug on the lower surface of a first substrate 100 and a flexible part is formed. An annular pedestal 220 is joined to the lower surface of a fixed part being located around the donut groove, and a weight body 210 is joined to an operation part that is located inside the donut groove. A second substrate 400 is joined to the upper part of the first substrate 100, electrodes El and E2 are formed at a surface that opposes both substrates 100 and 400, and a capacitance element is formed. A third substrate 300 is joined to the lower surface of the pedestal 220. The weight body 210 is suspended in the air and is displaced when being accelerated. The displacement causes the interval between the electrodes E1 and E2 to change, thus detecting acceleration as the change of capacitance. The first substrate 100, the pedestal 220, and the third substrate 300 exist in the upper direction of the weight body 210, in horizontal direction, and in the lower direction, respectively, thus controlling an excessive displacement and preventing the flexible part from being damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor utilizing a change in capacitance and a method of manufacturing the same, and more particularly, to a sensor using two sensors.
A sensor capable of detecting physical quantities such as force, acceleration, and magnetism based on a change in capacitance between a pair of electrodes formed on each of the substrates, and manufacturing suitable for mass-producing such a sensor About the method.

[0002]

2. Description of the Related Art In the automobile industry, the machine industry, and the like, there is an increasing demand for a detection device capable of accurately detecting physical quantities such as force, acceleration, and magnetism. In particular, a small device capable of detecting these physical quantities for each of two-dimensional or three-dimensional components is desired. To meet such demands, Japanese Patent Application Laid-Open
Japanese Patent Publication No. 148833 proposes a novel sensor utilizing a change in capacitance. This sensor is capable of detecting physical quantities such as force, acceleration, and magnetism for each two-dimensional or three-dimensional component, and has a feature of relatively low manufacturing cost.

The basic components of this sensor are a fixed portion fixed to the device housing, an operating portion to which an external force is transmitted, and a flexible portion formed between the fixed portion and the operating portion. A flexible substrate having three portions, a fixed substrate fixed to the device housing so as to face the flexible substrate, and a flexible substrate formed on a surface of the flexible substrate facing the fixed substrate. And a fixed electrode formed on the surface of the fixed substrate facing the flexible substrate. When an external force is applied to the action portion, the flexible substrate bends, and the distance between the displacement electrode and the fixed electrode changes. Therefore, the capacitance between both electrodes changes. This change in capacitance depends on an externally applied force, and the detection of the change in capacitance makes it possible to detect the force. If a weight is connected to the action part, it can be used as an acceleration sensor that detects acceleration acting on the weight, and if a magnetic substance is connected to the action part, it acts on this magnetic substance. It can be used as a magnetic sensor for detecting magnetism.

[0004]

In the above-mentioned sensor,
When an excessive acceleration or an excessive magnetic force acts, a weight body or a magnetic body connected to the acting portion is largely displaced, and an excessive force may be applied to the flexible substrate, which may cause physical damage. In particular, in order to realize a highly sensitive sensor, the flexible substrate must have a fragile structure in which bending is caused by the action of a slight force, and the flexible substrate is easily damaged when an excessive external force is applied. .

In order to supply the above-mentioned sensors at lower cost, it is essential to adopt an efficient mass production method. However, an efficient method for mass-producing the sensor having the above-described structure is not known at present, and mass production cannot be achieved. In particular, when used as an acceleration sensor or a magnetic sensor, it is necessary to join a weight body or a magnetic body to each unit, and a structure for supporting the weight body or the magnetic body with a predetermined degree of freedom is also necessary. Become. For this reason, there is a problem that the production cost is inevitably increased.

Accordingly, an object of the present invention is to provide a sensor utilizing a change in capacitance which is hardly damaged even when an excessive external force is applied, and to efficiently mass produce such a sensor. It is an object of the present invention to provide a manufacturing method capable of performing such a method.

[0007]

[Means for Solving the Problems]

(1) According to a first aspect of the present invention, in a sensor using a change in capacitance, an action portion is defined substantially at the center, a flexible portion is defined around the action portion, and a fixed portion is further defined around the action portion. A first substrate configured such that the flexible portion has flexibility by a groove formed in the portion, and an opposing surface fixed at a predetermined distance to an upper surface of the first substrate A second substrate, a first electrode layer formed on an upper surface of the first substrate, and a second electrode layer formed on a facing surface of the second substrate so as to face the first electrode layer And a pedestal joined to a fixed portion on the lower surface of the first substrate, and a pedestal joined to a fixed portion on the lower surface of the first substrate. The working body is displaced by mechanical deformation, and the capacitance of the capacitor formed by the first electrode layer and the second electrode layer is changed. The external force can be detected as a change in capacitance, and the inner surface of the pedestal and the outer surface of the operating body are configured to face each other at a predetermined interval. Can be limited within a predetermined range.

(2) A second aspect of the present invention is the above-mentioned first aspect.
In the sensor using the change in capacitance according to the aspect, an inner portion and an outer portion surrounding the inner portion are defined on the lower surface of the fixed portion of the first substrate, and a pedestal is formed on the defined outer portion. It is configured so that the defined inner portion and a part of the upper surface of the working body are opposed to each other at a predetermined distance so that the upward displacement of the working body is limited to a predetermined range by the defined inner portion. It is made possible.

(3) A third aspect of the present invention is the above-described first aspect.
Alternatively, in the sensor using the change in capacitance according to the second aspect, a third substrate joined to the lower surface of the pedestal is further provided, and the upper surface of the third substrate and the lower surface of the operating body are separated by a predetermined distance. In this configuration, the downward displacement of the acting body can be limited within a predetermined range by the upper surface of the third substrate.

(4) The fourth aspect of the present invention is the above-mentioned first aspect.
In the method for manufacturing a sensor using the change in capacitance according to the third aspect, the pedestal and the operating body are formed by the step of cutting a single substrate, and the pedestal and the working body are formed by the cutting path in this cutting step. It is possible to limit the lateral displacement of the working body within the space.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. The embodiment described here is an example in which the present invention is applied to an acceleration sensor using a change in capacitance.

§1. Basic Principle of Sensor According to the Present Invention Before describing a specific embodiment of the sensor according to the present invention, the structure and principle of a sensor to which the present invention is applied will be briefly described. FIG. 1 is a side sectional view showing a basic structure of an acceleration sensor to which the present invention is applied. The main components of this sensor are a fixed substrate 10,
The flexible substrate 20, the working body 30, and the device housing 40. FIG. 2 shows a bottom view of the fixed substrate 10. FIG. 1 shows a cross section of the fixed substrate 10 of FIG. 2 cut along the X-axis. The fixed substrate 10 is a disk-shaped substrate as shown, and the periphery thereof is fixed to the device housing 40. On the lower surface, a disk-shaped fixed electrode 11 is also formed. On the other hand, FIG. 3 shows a top view of the flexible substrate 20. FIG. 1 shows a cross section of the flexible substrate 20 of FIG. 3 cut along the X-axis. The flexible substrate 20 is also a disk-shaped substrate as shown, and the periphery thereof is fixed to the device housing 40. On this upper surface, fan-shaped displacement electrodes 21 to 24 and a disk-shaped displacement electrode 25 are formed as shown in the figure. The action body 30 has a columnar shape as shown by a broken line in FIG. 3, and is coaxially joined to the lower surface of the flexible substrate 20. The device housing 40 has a cylindrical shape and fixedly supports the periphery of the fixed substrate 10 and the flexible substrate 20.

The fixed substrate 10 and the flexible substrate 20 are arranged at predetermined positions at positions parallel to each other. Both are disc-shaped substrates, whereas the fixed substrate 10 has high rigidity and is unlikely to be bent, whereas the flexible substrate 20 has flexibility and becomes a substrate that bends when a force is applied. I have. Now, as shown in FIG. 1, an action point P is defined at the center of gravity of the action body 30, and an XYZ three-dimensional coordinate system having the action point P as an origin is defined as shown in the figure. That is, the X-axis is defined in the right direction in FIG. 1, the Z-axis is defined in the upward direction, and the Y-axis is defined in the direction perpendicular to the paper surface toward the back side of the paper surface. Here, assuming that the entire sensor is mounted on, for example, an automobile, acceleration is applied to the action body 30 based on the traveling of the automobile. Due to this acceleration, an external force acts on the action point P.
In a state where no force acts on the action point P, as shown in FIG. 1, the fixed electrode 11 and the displacement electrodes 21 to 25 maintain a parallel state at a predetermined interval. However, for example, when a force Fx in the X-axis direction acts on the action point P, the force Fx generates a moment force on the flexible substrate 20,
As shown in FIG. 4, the flexible substrate 20 is bent. Due to this bending, the distance between the displacement electrode 21 and the fixed electrode 11 increases, but the distance between the displacement electrode 23 and the fixed electrode 11 decreases. Assuming that the force applied to the point of action P is -Fx in the opposite direction, the bending in the opposite relationship to this occurs. When the force Fx or −Fx acts in this manner, a change appears in the capacitance of the displacement electrodes 21 and 23, and by detecting this, the force Fx is detected.
x or -Fx can be detected. At this time, the distance between each of the displacement electrodes 22, 24, and 25 and the fixed electrode 11 partially increases or decreases, but it may be considered that the distance does not change as a whole. On the other hand, when a force Fy or −Fy in the Y direction acts, the displacement electrode 2
Similar changes occur only in the interval between the fixed electrode 11 and the displacement electrode 24 and the interval between the displacement electrode 24 and the fixed electrode 11.
When the force Fz in the Z-axis direction acts, as shown in FIG. 5, the distance between the displacement electrode 25 and the fixed electrode 11 decreases, and when the force −Fz in the opposite direction acts, this distance becomes growing. At this time, the distance between the displacement electrodes 21 to 24 and the fixed electrode 11 also becomes smaller or larger, but the change relating to the displacement electrode 25 is the most remarkable. Therefore, the force Fz or -Fz can be detected by detecting a change in the capacitance of the displacement electrode 25.

In general, the capacitance C of a capacitance element is determined by C = εS / d, where S is an electrode area, d is an electrode interval, and ε is a dielectric constant. Therefore, the capacitance C increases as the distance between the opposing electrodes decreases, and decreases as the distance increases. This sensor uses this principle to measure the change in capacitance between the electrodes, and based on the measured value, the point of action P
Is to detect the external force that acts on the vehicle, in other words, the acceleration that acts. That is, the acceleration in the X-axis direction is
Based on the capacitance change between the fixed electrodes 11 and 23, Y
The axial acceleration is detected based on the capacitance change between the displacement electrodes 22 and 24 and the fixed electrode 11, and the Z-axis acceleration is detected based on the capacitance change between the displacement electrode 25 and the fixed electrode 11, respectively. . The present invention proposes a more specific structure for a sensor based on such a principle.

§2. Manufacturing Process I of Sensor According to the Present Invention Here, in order to show the structure of the sensor according to the present invention, a manufacturing method thereof will be described. The feature of the manufacturing method shown here is that a plurality of sensor units are formed on one substrate, and this is cut (diced) for each unit later. First, as a manufacturing process I, a process until dicing for each unit will be described. First, a plurality of unit areas are defined on the main substrate.
The main substrate is separately cut for each unit region in a later dicing step, and each functions independently as a displacement substrate. FIG. 6 shows a plurality of unit regions formed on the main substrate 100. The hatched portion is one unit area, and each unit area is square. When a wafer such as a semiconductor is used as the main substrate 100, it is common to form a large number of unit regions on a disk-shaped substrate as described above, but here, for convenience of description, as shown in FIG. The following description will be continued with an example in which four unit regions are formed on a square main substrate 100.

FIG. 8 is a sectional view showing each step of the manufacturing method. Hereinafter, this step will be described in detail. First, the main substrate 100 is processed as shown in FIG. In this embodiment, a single crystal silicon substrate is used as the main substrate 100.
A substrate of another material such as a glass substrate may be used. As described above, the main substrate 100 has a square shape for convenience of description, and is divided into four unit regions. Therefore, the same processing is performed on each of the four unit regions. FIG. 9B is a bottom view of the main substrate 100 after processing, and FIG.
FIG. 4 is a side sectional view showing a state of cutting this along a cutting line aa. On the upper surface of the main substrate 100, a first electrode layer E1 is formed at a predetermined position. The first electrode layer E1 corresponds to the five displacement electrodes 21 to 25 shown in FIG. 3 (three cross sections are shown in FIG. 9 for two units), and FIG. It is formed at the position as shown. In this embodiment, a main substrate 10 made of a single crystal silicon substrate is used.
The first electrode layer E1 is formed on the surface of the first electrode layer by diffusing impurities. In addition, the first electrode layer E1 may be formed on the main substrate 100 by a method of attaching an aluminum layer. In short, the first electrode layer E1 may be formed by any method as long as it can form a layer having conductivity. However, the method of forming the impurity diffusion layer or the method of forming the aluminum layer is preferable in that the technique of the conventional semiconductor planar process can be used as it is. On the other hand, a groove 101 is formed on the lower surface of the main substrate 100 by a method such as etching.
The thickness of the portion is reduced to provide flexibility. In this embodiment, the groove 101 has a circular shape as shown in FIG. The inside of the groove 101 is the action part 110, the outside is the fixing part 130, and the groove part is the flexible part 120. Of the first electrode layer E1, the displacement electrode 21 shown in FIG.
Those corresponding to .about.24 are formed in the flexible part 120 just above the groove, and those corresponding to the displacement electrode 25 are formed in the action part 110 surrounded by the groove.
FIG. 8A shows a state in which the processing of the main substrate 100 has been completed.

Next, an auxiliary substrate 200 as shown in FIG. 10 is prepared. Since a part of the auxiliary substrate 200 eventually constitutes the weight body and the remaining part thereof constitutes the pedestal, a material suitable for the weight body and the pedestal is used. Further, since the main substrate 100 is bonded to the main substrate 100, it is preferable to use a material having a thermal expansion coefficient substantially equal to that of the main substrate 100. For example, it is preferable to use the same silicon substrate or glass substrate as the main substrate 100. FIG. 10B is a top view of the auxiliary substrate 200 after processing,
(a) is a side sectional view showing a state of cutting this along a cutting line aa. Thus, the grooves 201 and 202 are formed on the upper surface of the auxiliary substrate 200 vertically and horizontally. The groove 201 is a deep groove having a width L1, and the groove 202 is a shallow groove having a width L2. The groove 201 is for facilitating the dicing of the substrate later. The position where the groove 201 is formed is, in short, a portion 210 (four portions in the drawing) corresponding to the action portion 110 of the main substrate 100 and the fixing portion 13.
The portion 220 (the other portion) corresponding to 0 may be located at a position where it can be separated. In other words, the auxiliary substrate 200 is overlapped on the main substrate 100 and joined,
When only the auxiliary substrate 200 is cut along the auxiliary substrate 200, the auxiliary substrate 200 is divided into a weight (part 210) and a pedestal (part 220).
What is necessary is just to separate it. The groove 202 is for giving a degree of freedom regarding upward displacement of the weight body after cutting. When such an auxiliary substrate 200 is prepared, it is attached to the main substrate 100 as shown in FIG.
To join. This bonding may be performed by bonding with an adhesive, but it is preferable to use anodic bonding that can directly bond materials to each other in order to perform reliable bonding. That is, a voltage is applied between the two, the temperature of the two is raised, and bonding is performed while applying pressure.

Subsequently, as shown in FIG. 8C, the auxiliary substrate 200 is cut along the groove 201 with a dicing blade. The cutting path 203 is on the opposite side of the groove 201 (below the figure).
Formed. As a result, the portion 210 (which becomes a weight body) and the portion 220 (which becomes a pedestal) are completely separated. As shown in FIG.
0 (weight body) is located at four places, which is shown in FIG.
Are joined only to the action portion 110 shown in FIG. Further, the other part 220 (pedestal) is in a state of being joined only to the fixing part 130 shown in FIG. 9B. Since the flexible portion 120 is in a state of being floated from the auxiliary substrate 200, it is not joined to any portion. In this manner, by dicing the auxiliary substrate 200, the weight body 210 and the pedestal 220 can be simultaneously formed. Here, the pedestal 220 not only functions as a pedestal that supports the fixing unit 130, but also functions as a control member that controls the lateral displacement of the weight body 210 so as not to exceed an allowable range. This allowable range is determined by the width of the cutting path 203 (when the width of the groove 201 is smaller than the width of the cutting path 203, it is determined by the width of the groove 201). Note that the dicing step performed here is a dicing step for only the auxiliary substrate 200, and the main substrate 100 is still in a single state.

Next, a control board 300 as shown in FIG.
Prepare The control board 300 is for controlling the downward displacement of the weight body 210 within an allowable range. As a material, a silicon substrate or a glass substrate may be used as in the case of the auxiliary substrate 200. This control board 300
Exactly the same processing is performed on each of the four unit regions on the upper surface of the. FIG. 11B is a top view of the control board 300 after processing, and FIG. 11A is a side sectional view showing a state where the control board 300 is cut along a cutting line aa. Square grooves 301 are formed in four places on the upper surface. The groove 301 is for controlling the degree of freedom in the downward direction of the displacement of the weight body 210, and the degree of freedom is determined by the depth of the groove 301. The control board 300 is bonded to the auxiliary board 200 as shown in FIG. It is preferable to use anodic bonding also for this bonding.

Next, a sub-board 400 as shown in FIG. 12 is prepared. This sub-substrate 400 is for supporting the second electrode layer E2. As a material, the main board 100
Similarly, a silicon substrate or a glass substrate may be used. Exactly the same processing is performed on the lower surface of the sub-substrate 400 for each of the four unit regions. In FIG.
(b) is a bottom view of the sub-substrate 400 after processing, and (a) is a side cross-sectional view showing a state of cutting the same along a cutting line aa. On the lower surface, square grooves 401 are formed at four places, and second electrode layers E2 are formed on the bottom surfaces of the grooves 401, respectively. The second electrode layer E2 corresponds to the fixed electrode 11 shown in FIG. 3, and is formed at a position shown in FIG. 3, that is, a position facing the displacement electrodes 21 to 25. In this embodiment, after a groove 401 is formed on the surface of a sub-substrate 400 made of a single crystal silicon substrate by etching or the like, the second electrode layer E2 is formed by a method of attaching an aluminum layer to the bottom surface of the groove 401. Has formed. Of course, like the first electrode layer E1, the second electrode layer E2 may be formed by an impurity diffusion method. In short, the second electrode layer E2 can be formed by any method that can form a layer having conductivity.
May be formed. However, the method of forming the impurity diffusion layer or the method of forming the aluminum layer is preferable in that the technique of the conventional semiconductor planar process can be used as it is. The formation of the groove 401 and the formation of the second electrode layer E2 can be performed with extremely high precision by utilizing micromachining technology used in a semiconductor process. Another feature of the sub-substrate 400 is that the lateral width is slightly shorter than other substrates, and a vertically long groove 402 is formed at the center. This is a contrivance for the convenience of wire bonding, as will be described later. This sub-substrate 400 is
As shown in (a) of FIG. It is preferable to use anodic bonding also for this bonding. In this way, the first electrode layer E1 and the second electrode layer E2 face each other in the upper and lower parts of the figure. It is preferable to make the distance between the two electrodes as narrow as possible in order to increase the capacitance and perform highly sensitive measurement. If the above-mentioned micromachining technology is used, the distance between both electrodes can be reduced to about several μm.

Thereafter, as shown in FIG.
02 is cut off by a cutting path 403. Further, as shown in FIG. 13C, when each unit area is cut along the cutting path 510, the four unit areas shown in FIG. 7 are respectively separated, and the sensor center part 500 is completed. FIG. 14 shows a perspective view of the completed sensor center part 500. Sub-board 4
The reason why the width of 00 is shortened and the vertically long groove 402 is formed is that the bonding pad 501 is exposed as shown in FIG.

§3. Manufacturing process II of the sensor according to the present invention Next, the process after dicing each substrate will be described. When the sensor center 500 as shown in FIG. 14 is obtained, it is housed inside the package 600 as shown in the side sectional view of FIG. That is, the sensor center 5
The bottom of 00 may be adhered to the inside of the package 600. Mounting leads 610 are attached to the package 600, and the bonding pads 501 and the inner ends of the leads 610 are bonded by bonding wires 620. Thereafter, if the package 600 is covered with a lid 630 and sealed, the acceleration sensor is completed.

As described above, the manufacturing process of each unit after dicing (the above-described manufacturing process II) is much simpler than the manufacturing process of each substrate (the above-described manufacturing process I). That is, according to the above-described method, most of the manufacturing steps can be performed for each substrate, and efficient manufacturing suitable for mass production becomes possible.

§4. Features of the Sensor According to the Present Invention In the sensor shown in FIG.
It is joined to the action part in the center part of, and is suspended. When acceleration acts on this sensor, the main board 100
Since the flexible portion, which is a thin portion of the weight, is bent, the weight 2
10 is displaced in a suspended state. Due to such displacement, the first electrode layer E1 and the second electrode layer E2
Is changed as described above, and the acceleration acting as a change in the capacitance of the capacitive element formed by both electrode layers can be detected as described in §1.

In the sensor having such a structure, as described in each part of the manufacturing process in §2, the weight 210
A control member for controlling the displacement of is provided. First, the pedestal 220 functions as a control member that controls the lateral displacement of the weight body 210 so as not to exceed an allowable range. The pedestal 220 is joined to the bottom surface of the outer part of the fixing part that forms the peripheral part of the main substrate 100. On the other hand, the bottom surface of the inner portion of the fixed portion functions as a control member that controls the upward displacement of the weight body 210 so as not to exceed an allowable range. Further, the control board 300
Functions as a control member for controlling the downward displacement of the weight body 210 within an allowable range. Therefore, even if an excessive acceleration acts on this sensor, the upward, lateral, and downward displacements of the weight body 210 are limited by these control members, and the flexible portion of the main board 100 is restricted. No excessive stress is applied. In this embodiment, a single crystal silicon substrate is used as the main substrate 100. However, even when an excessive acceleration is applied, mechanical damage to the main substrate 100 is caused by the functions of the control members described above. Will not occur.

§5. While the other embodiments have been described with reference to one embodiment illustrating the invention,
The present invention is not limited to only this embodiment,
It can be implemented in various ways. Hereinafter, embodiments according to other aspects will be exemplified.

(1) In the above embodiment, the control board 30
However, the first basic idea of the present invention is that the weight and the pedestal are formed by the auxiliary substrate 200, and the lateral displacement of the weight is limited by the pedestal. Therefore, the step of bonding the control substrate 300 is not always necessary. Also, the thickness of the weight body 210 is made slightly smaller than the thickness of the pedestal 220 by shaving the bottom surface of the weight body 210, and the bottom surface of the pedestal 220 is directly packaged.
It may be joined to the inner bottom surface of 00. Weight 210
Is slightly small, so that the weight 210 can be kept floating from the inner bottom surface of the package 600 when no acceleration is applied.

(2) In the above embodiment, an example in which the present invention is applied to an acceleration sensor has been described. However, the present invention can be similarly applied to a magnetic sensor. However, in the case of the acceleration sensor, the weight acting on the acting portion is the weight 210, whereas in the case of the magnetic sensor, the weight must be a magnetic body. Therefore, the auxiliary substrate 2
As the material of 00, a magnetic material is used.

(3) In the auxiliary substrate 200 shown in FIG.
The groove 201 is formed in advance. The groove 201 is for facilitating the operation of cutting the auxiliary substrate 200 in a later step, and is not always necessary. If the auxiliary substrate 200 can be cut well later, the groove 201 is unnecessary.

(4) In the control board 300 shown in FIG.
Although the square groove 301 is formed for each unit region, a control substrate 300 ′ having an elongated groove 302 formed over the unit region as shown in FIG. 17 may be used instead.

(5) In the above embodiment, as shown in FIG. 14, the electrical connection between the bonding pad 501 and each electrode layer (not shown in FIG. 14) is made by a diffusion layer inside the main substrate. Is being done. However, in the case of a type in which a wiring layer 502 made of aluminum or the like is formed on a substrate and an electrical connection between them is made, as in a sensor center portion 500 'shown in FIG. 16, a gap 503 for the wiring layer 502 is formed. Need to be secured. In this case, instead of the sub-substrate 400 shown in FIG. 12, the groove 40 shown in FIG.
4 may be used.

(6) As described above, in the above-described embodiment, for convenience of explanation, an example in which four sets of sensor centers are manufactured using the square substrate shown in FIG. 7 has been described.
A larger number of sensor centers can be manufactured using a disk-shaped wafer as shown in FIG. Of course, one substrate (wafer)
, Only one set of sensor cores may be manufactured.

(7) In the above embodiment, the weight 210
The space around is filled with air, but if silicone oil or the like is sealed in this space, the effect of absorbing shock and vibration is obtained, and the shock resistance and vibration resistance are improved.

(8) In order to extract a change in capacitance as a signal, generally, an oscillation circuit connected to a capacitance element, an amplification circuit for amplifying the output of the oscillation circuit, and counting the frequency of the amplified signal are performed. A counting circuit is required,
If the main substrate 100 is formed of a semiconductor substrate, these circuits can also be formed on the main substrate 100.

(9) As shown in FIGS. 2 and 3, in the embodiment described here, one fixed electrode 11 is provided on the fixed substrate 10 side, and five displacement electrodes 21 to 25 are provided on the displacement substrate 20 side.
However, conversely, five fixed electrodes may be formed on the fixed substrate 10 side, and one displacement electrode may be formed on the displacement substrate 20 side.

(10) In the above embodiment, one of the opposing electrodes is formed of one electrode layer, and the other is formed of five electrode layers. In this case, one electrode layer is used as a common electrode due to the configuration of the detection circuit. On the other hand, both may form five electrode layers. In this case, five sets of completely independent capacitance elements are configured, and detection processing with more flexibility can be performed.

(11) In the above-described embodiment, five displacement electrodes 21 to 25 are arranged in the form shown in FIG. 3 to detect three-dimensional acceleration, but the displacement electrode 25 is not used. It is also possible to detect the acceleration component in the Z-axis direction. That is,
It is also possible to detect acceleration in a three-dimensional direction by using only four displacement electrodes 21 to 24 (for details, see Japanese Patent Application Laid-Open No.
No. 8833). However, when performing accurate measurement while suppressing interference of other axis components, an arrangement of five electrodes as shown in FIG. 3 is ideal. In other words, it is preferable that the detection of the component in the Z-axis direction is performed by the electrode 25 disposed at the center, and the detection of the component in the X-axis or Y-axis direction is performed by the electrodes 21 to 24 disposed therearound. It can be understood from FIG. 4 that the displacement of the electrodes 21 to 24 is more remarkable than the displacement of the electrode 25 when a force in the X-axis or Y-axis direction component is applied (because the electrode 25 is disposed at the center). It can be considered that there is no displacement as a whole). Therefore, to detect the X-axis or Y-axis direction component, the electrode 2
Suitably, 1 to 24 is used. Also, it can be understood from FIG. 5 that when the force in the Z-axis direction component acts, the displacement of the electrode 25 is more remarkable than the displacement of the electrodes 21 to 24. Therefore, it is applicable to use the electrode 25 to detect the Z-axis direction component.

[0038]

As described above, according to the present invention, in a sensor utilizing a change in capacitance, a control member is provided around an operating body in a suspended state, so that even when an excessive external force acts. It is possible to provide a sensor using a change in capacitance that is not easily damaged. Further, since the acting body and the pedestal are formed by cutting one substrate, such a sensor can be efficiently mass-produced.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a basic structure of an acceleration sensor to which the present invention is applied.

FIG. 2 is a bottom view of a fixed substrate 10 of the sensor shown in FIG. FIG. 1 shows a cross section of the fixed substrate 10 of FIG. 2 cut along the X-axis.

FIG. 3 is a top view of a flexible substrate 20 of the sensor shown in FIG. FIG. 1 shows a cross section of the flexible substrate 20 of FIG. 3 cut along the X-axis.

FIG. 4 shows a force F in the X-axis direction applied to an action point P of the sensor shown in FIG.
It is a sectional side view which shows the bending state of a sensor when x acts.

FIG. 5 shows a force F in the Z-axis direction at an action point P of the sensor shown in FIG.
It is a sectional side view which shows the bending state of a sensor when z acts.

FIG. 6 is a diagram showing a state in which a unit area is defined on a substrate in order to manufacture a sensor according to a specific embodiment of the present invention.

FIG. 7 is a diagram showing a state in which a simpler unit area is defined for convenience of explanation.

FIG. 8 is a process diagram showing a previous stage of the method of manufacturing the central part of the acceleration sensor according to one embodiment of the present invention.

9 is a diagram showing a side cross section and a lower surface of a main substrate used in the method shown in FIG.

FIG. 10 is a side sectional view and a bottom view of an auxiliary substrate used in the method shown in FIG. 8;

11 is a side sectional view and a bottom view of a control board used in the method shown in FIG. 8;

FIG. 12 is a side sectional view and a bottom view showing a sub-substrate used in the method shown in FIG. 8;

FIG. 13 is a process diagram showing a later stage of the method of manufacturing the central part of the acceleration sensor according to the embodiment of the present invention.

FIG. 14 is a perspective view showing a central portion of the acceleration sensor manufactured by the method shown in FIG.

FIG. 15 is a side sectional view showing a state where the central part of the acceleration sensor shown in FIG. 14 is accommodated in a package.

FIG. 16 is a perspective view showing a central portion of an acceleration sensor according to another embodiment of the present invention.

FIG. 17 is a side sectional view and a top view of a control board used in a sensor according to another embodiment of the present invention.

FIG. 18 is a side sectional view and a bottom view showing a sub-substrate used for a sensor according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Fixed board 11 ... Fixed electrode 20 ... Flexible board 21-25 ... Displacement electrode 30 ... Working body 100 ... Main board 101 ... Groove 110 ... Working part 120 ... Flexible part 130 ... Fixed part 200 ... Auxiliary board 201, 202 ... Groove 203. Cutting path 210... Weight body 220... Pedestal 300, 300 ′... Sensor central portion 501 Bonding pad 502 Wiring layer 503 Wiring layer gap 510 Cutting path 600 Package 610 Lead 620 Bonding wire 630 Cover E1 First electrode layer E2 Second electrode layer

Claims (4)

[Claims] An action portion substantially at the center, a flexible portion around the action portion,
A first substrate having a fixed portion defined around the first substrate, the first substrate being configured such that the flexible portion has flexibility by a groove formed in the lower portion of the flexible portion; A second substrate having an opposing surface fixed at a predetermined distance from an upper surface of the first substrate, a first electrode layer formed on the upper surface of the first substrate, and an opposing surface of the second substrate. A second electrode layer formed on the surface so as to face the first electrode layer; an operating body joined to the operating portion on a lower surface of the first substrate; and a lower surface of the first substrate And a pedestal joined to the fixed portion of (a). When an external force acts on the working body, the working body is displaced by mechanical deformation of the flexible part, and the first electrode layer and the second The capacitance of the capacitance element formed by the electrode layer is configured to change, and the external force is applied to the capacitance. It has a function of detecting as a change in the amount, the inner surface of the pedestal, the outer surface of the operating body is configured to oppose at a predetermined interval, the inner surface of the pedestal of the operating body A sensor using a change in capacitance, wherein a displacement in a lateral direction can be limited within a predetermined range. 2. The sensor according to claim 1, wherein an inner portion and an outer portion surrounding the inner portion are defined on a lower surface of the fixed portion of the first substrate, and a pedestal is joined to the outer portion. The inner part and a part of the upper surface of the working body are configured to face each other at a predetermined interval, and the upward displacement of the working body can be limited to a predetermined range by the inner part. A sensor utilizing a change in capacitance, characterized in that: 3. The sensor according to claim 1, further comprising a third substrate bonded to a lower surface of the pedestal, wherein an upper surface of the third substrate and a lower surface of the operating body are spaced at a predetermined distance. A sensor using a change in capacitance, wherein a downward displacement of the operating body can be limited to a predetermined range by an upper surface of the third substrate. 4. A method for manufacturing a sensor according to claim 1, wherein a pedestal and an operating body are formed by a step of cutting a single substrate, and formed by a cutting path in the cutting step. A method for manufacturing a sensor using a change in capacitance, wherein a lateral displacement of the operating body can be limited within a range of a closed space.