JP2004012329A - Capacity-regulable physical quantity detector and manufacturing method of capacity-regulable physical quantity detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a physical quantity detector of high measuring precision, and a manufacturing method thereof. <P>SOLUTION: In this capacity-regulable detector (for example, detecting part 100) provided with a movable electrode plate 21 supported displaceably by an elastic part 22, and at least one fixed electrode plate 11, 31 in a position faced to the movable electrode plate, to detect one out of physical quantities comprising a displacement, a speed and an acceleration of a measured body, based on an electrostatic capacity of a capacitor formed with the movable electrode plate and the fixed electrode plate, the fixed electrode plate(s) is/are on glass substrates 1, 3, and the fixed electrode plate is provided with a main body part (for example, main body part electrode plate 111), and a regulation part (for example, electrode plate 12 for regulation) connected to the main body part to regulate the electrostatic capacity. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a physical quantity detector for detecting physical quantities such as acceleration, displacement, pressure, and the like, and more particularly to a physical quantity detector capable of detecting a physical quantity based on a capacitance difference and capable of adjusting a capacitance, and a method of manufacturing the same.
[0002]
[Prior art]
Conventionally, various types of capacitance type physical quantity detectors have been provided, and for example, an acceleration sensor described in Japanese Patent Application Laid-Open No. 9-243654 is known.
In the acceleration sensor 100, for example, as shown in FIG. 4, a first glass substrate 102 is bonded to a lower surface of a silicon substrate 101, and a second glass substrate 103 is bonded to an upper surface of the silicon substrate 101. The weight 101b of the silicon base 101 is supported by a cantilever via a beam 101c, and is connected to a support frame 101a having a flat square shape formed by etching. Further, a predetermined gap is formed between the upper and lower surfaces of the weight portion 101b and the opposing surfaces of the opposing glass substrates 102 and 103. Thereby, when receiving an acceleration, the beam portion 101c bends, the weight portion 101b is displaced, and the distance of the gap changes.
[0003]
Then, movable electrodes 104 are formed on both surfaces of the weight portion 101b, and first fixed electrodes 105 are respectively formed on inner surfaces of the first glass substrate 102 and the second glass substrate 103 so as to face the movable electrodes 104. And the second fixed electrode 106 are formed. Therefore, when the weight 101b is displaced and the distance of the gap changes, a first capacitor is formed between the movable electrode 104 and the first fixed electrode 105, and a second capacitor is formed between the movable electrode 104 and the second fixed electrode 106. Are formed, and the capacitance of the first capacitor and the second capacitor also changes as the movable electrode 104 moves. By detecting the change in the capacitance, the acceleration based on the displacement of the weight portion 101b can be detected.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional physical quantity detector, capacitors are formed above and below the weight portion 101b, but are detected by the upper and lower capacitors in a steady state due to distortion or the like in the process of forming the weight portion 101b. However, there is a problem that it is difficult to bring the capacitance value into an equilibrium state and a mechanical error occurs.
Moreover, since the error cannot be confirmed until after the physical quantity detector is assembled, it is difficult to mechanically correct the error.
[0005]
In view of the above, an object of the present invention is to provide a physical quantity detector with higher measurement accuracy and a method for manufacturing the same.
[0006]
[Means for Solving the Problems]
To solve the above problems, the following means are provided. The numbers in parentheses indicate the reference numerals of the corresponding components in the embodiment.
The invention according to claim 1 is characterized in that the movable electrode plate 21 movably supported by the elastic portion 22,
Fixed electrode plates 11 and 31 arranged at positions facing the movable electrode plate,
A capacitance-adjustable physical quantity detector (e.g., detection) that detects any physical quantity of displacement, velocity, or acceleration of the measured object based on the capacitance of a capacitor formed by the movable electrode plate and the fixed electrode plate. In part 100),
The fixed electrode plate is formed on a light-transmitting material (for example, glass substrates 1, 3),
The fixed electrode plate is provided with a main body (for example, main body electrode plate 111) and an adjustment unit (for example, an adjustment electrode plate 112) connected to the main body and for adjusting the capacitance. It is characterized by having.
[0007]
Here, the position, size, shape, and number of the adjustment units may be arbitrarily determined.
According to the first aspect of the present invention, since the fixed electrode plate is provided with the adjusting unit for adjusting the capacitance, when an error occurs in the capacitance value, the adjusting unit of the fixed electrode plate is adjusted. The capacitance value can be easily adjusted by separating it from other parts. Therefore, more accurate physical quantity measurement can be performed.
[0008]
According to a second aspect of the present invention, in the physical quantity detector capable of adjusting the capacity according to the first aspect,
The adjustment section is configured by a plurality of adjustment electrode plates having a known capacitance.
[0009]
According to the second aspect of the present invention, it is needless to say that the same effect as that of the first aspect of the invention can be obtained. In particular, the adjusting section is constituted by a plurality of adjusting electrode plates having a known capacitance. Therefore, the adjustment electrode plate can be selected according to the error, and more accurate physical quantity measurement can be performed.
[0010]
According to a third aspect of the present invention, there is provided a method for manufacturing a physical quantity detector capable of adjusting a capacity according to the first or second aspect,
Forming a movable electrode plate on a base (for example, a silicon base 2);
Forming the fixed electrode plate on the translucent material;
Coupling the base and the translucent material such that the movable electrode plate and the fixed electrode plate face each other with a predetermined distance therebetween;
Next, the capacitance of the capacitor formed by the movable electrode plate and the fixed electrode plate is measured, and based on the measurement result, at least a part of the adjustment unit of the fixed electrode plate and the main body portion Disconnecting the connection with a laser;
It is characterized by having.
[0011]
According to the third aspect of the present invention, the base and the light-transmitting material are coupled to each other so that the movable electrode plate and the fixed electrode plate face each other with a predetermined distance therebetween, and are formed by the movable electrode plate and the fixed electrode plate. The capacitance of the capacitor to be measured is measured, based on the measurement result, since the connection between at least a part of the adjustment electrode plate and the main body is cut off by the laser, after assembling and manufacturing the physical quantity detector, It is possible to easily perform mechanical correction of an error generated in a manufacturing process.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a capacitive acceleration sensor according to an embodiment of the present invention will be described with reference to FIGS.
The capacitance-type acceleration sensor includes a detection unit 100, a control unit (not shown), and a lead L connecting these components. Among these, as shown in FIGS. 1 and 2, the detection unit 100 includes a silicon substrate 2 disposed at the center, and two glass substrates 1 and 2 as two translucent members sandwiching the silicon substrate 2 from above and below. The base 3 is formed by anodic bonding. Most of the silicon substrate 2 is constituted by a silicon main body 20. The main body 20 has an elastic portion 22 and a circular shape in a plan view supported by the elastic portion 22 so as to be displaceable in the thickness direction. The movable electrode plate 21 is provided integrally by etching.
[0013]
In the upper glass substrate 1, a gap (gap) of several microns is secured at a position facing the movable electrode plate 21, and the first fixed electrode plate 11 is formed by a method such as vapor deposition or sputtering. Is filmed.
The first fixed electrode plate 11 includes a main body electrode plate 111 (main body portion) that corresponds to an area occupied by the fixed electrode plate 21 and the elastic portion 22 in a projection view, and is electrically connected to the main body electrode plate 111. It is composed of connected adjustment electrode plates 112 (adjustment unit).
From the first fixed electrode plate 11, a first L-shaped detection electrode 113 composed of a thin film layer of titanium and platinum extends toward the projection region of the island 4 of the silicon substrate 2.
[0014]
The adjustment electrode plates 112 are provided at the four corners of the main body electrode plate 111 and each have a triangular shape. A connection portion having a slight width is provided between the main body electrode plate 111 and the adjustment electrode plate 112. 11a are electrically connected. Accordingly, by cutting the connection portion 11a with a laser or the like, the electrical connection between the main body portion electrode plate 111 and the adjustment electrode plate 112 can be cut off.
Each of the adjusting plates 112 has a known capacitance and is set to be different.
[0015]
Further, on the upper glass substrate 1, around the first fixed electrode plate 11, lead wire mounting portions 13, 14, 15 as through holes are provided at predetermined positions. The lead wire attaching portions 13 and 14 are arranged so as to communicate with the islands 4 and 5, respectively.
[0016]
On the other hand, on the lower glass substrate 3, a gap of several microns is secured at a position facing the movable electrode plate 21, and the second fixed electrode plate 31 is formed by a method such as evaporation or sputtering. Is filmed.
The second fixed electrode plate 31 is electrically connected to a main body electrode plate 311 (main body portion) corresponding to an area occupied by the fixed electrode plate 21 and the elastic portion 22 in a projection view. (Adjusting unit) to be connected.
From the first fixed electrode plate 11, a first L-shaped detection electrode 113 made of an alloy of titanium and platinum extends toward the projection area of the island 4 of the silicon substrate 2.
[0017]
Are provided at the four corners of the main body electrode plate 311 and each have a triangular shape, and a connection portion having a slight width is provided between the main body electrode plate 311 and the adjustment electrode plate 312. 31a are electrically connected. Accordingly, by cutting the connection portion 31a with a laser or the like, the electrical connection between the main body portion electrode plate 311 and the adjustment electrode plate 312 can be cut off.
Each of the adjusting electrode plates 312 has a known capacitance and is set to be different.
[0018]
In the main body portion 20 of the silicon substrate 2 sandwiched between the glass substrate 1 and the glass substrate 2 configured as described above, the movable electrode plate 21 is formed in a circular shape in plan view as shown in FIG. A plurality of elastic support members are regularly and uniformly arranged at equal intervals on the periphery of the electrode plate 21 in the direction of the fold line. The elastic part 22 is constituted by these elastic supporting members.
By configuring the elastic portion 22 in this manner, the stress generated when manufacturing the elastic portion 22 can be released, and the elastic portion 22 having no residual stress is realized.
[0019]
FIG. 3 is a schematic cross-sectional view of the detection unit 100. As shown, each of the elastic supporting members is vertically positioned on the upper surface and the lower surface of the periphery of the movable electrode plate 21. It consists of two beams.
Further, as is clear from FIG. 2, the elastic portion 22 is disposed at a position depressed inward from each surface of the movable electrode plate 21.
[0020]
After the movable electrode plate 21 and the elastic portion 22 are subjected to masking corresponding to the movable electrode plate 21 and the respective elastic support members on the plate-shaped silicon substrate 2 constituting the body portion 20, the silicon substrate 2 Is formed integrally by etching the substrate.
At this time, in order to secure a gap between the movable electrode plate 21 and each of the fixed electrode plates 11 and 31, the surface of the portion where the movable electrode plate 21 is to be formed on the silicon substrate 2 is left. It is etched away so as to be several microns lower than the surface of the part. Further, the etching is performed so that the elastic portion 22 is arranged at a position depressed lower than the surface of the movable electrode plate 21.
[0021]
As described above, since the movable electrode plate 21, the elastic portion 22, and the main body portion 20 are integrally formed, the movable electrode plate 21 and the main body portion 20 are electrically connected through the elastic portion 22. Become.
[0022]
Further, silicon islands 4 and 5 for taking out electrodes are provided at predetermined positions around the movable electrode plate 21 in the silicon substrate 2. The respective islands 4 and 5 are arranged so as to be separated from each other so as not to contact the other islands and the main body 20, and are therefore electrically insulated from the other islands and the main body 20.
Of these, the island 4 is arranged at a position overlapping with the lead wire attaching portion 13 in a projection view from the plane direction, and the island 5 is similarly arranged at a position overlapping with the lead wire attaching portion 14 in a projection view. Have been.
[0023]
Further, a housing 27 for receiving a getter G as a gas adsorbent is provided at a predetermined position of the silicon substrate 2.
[0024]
In the process of manufacturing the capacitance type acceleration sensor, first, the getter G is housed in the housing part 27, and then the glass substrate 1, the silicon substrate 2, and the glass substrate 3 are anodically bonded. Thereby, the movable electrode plate 21, the fixed electrode plates 11, 31, and the getter G are sealed.
At this time, the first detection electrode 113 and the island 4 are in contact with each other, and the second detection electrode 313 and the island 5 are in contact with each other.
[0025]
Next, the getter G is irradiated with a YAG laser via the glass substrate 1 or the glass substrate 3 as a light transmitting material. Thereby, the getter G is heated and activated, and the getter G absorbs the gas (atmosphere) surrounding the movable electrode plate 21, the fixed electrode plates 11, 31 and the like. Thus, the movable electrode plate 21, the fixed electrode plates 11, 31 and the like are arranged in a vacuum.
[0026]
The lead wires L are bonded to the respective lead wire mounting portions 13, 14, 15 provided on the glass substrate 101 by the conductive epoxy E.
Therefore, the lead wire L bonded to the lead wire attaching portion 13 is electrically connected to the first fixed electrode plate 11, and the lead wire L bonded to the lead wire attaching portion 14 is electrically connected to the second fixed electrode plate 31. The lead wire L that is electrically connected and bonded to the lead wire attaching portion 15 is electrically connected to the movable electrode plate 21 via the main body portion 20.
Further, each of the lead wires L is connected to a control unit (not shown).
[0027]
The correction process of the capacitor of the capacitance type acceleration sensor configured as described above is as follows.
First, in the capacitance type acceleration sensor, a control unit (not shown) controls the potential of the first fixed electrode plate 11 detected via the lead wire L bonded to the lead wire mounting unit 13 and the lead wire. On the basis of the potential of the movable electrode plate 21 detected via the lead wire L bonded to the mounting portion 15, a variable capacitor (hereinafter, referred to as a capacitor) formed by the first fixed electrode plate 11 and the movable electrode plate 21. , "First capacitor").
[0028]
The control unit (not shown) determines the potential of the second fixed electrode plate 31 detected via the lead wire L bonded to the lead wire mounting unit 14 and the lead L bonded to the lead wire mounting unit 15. Of the variable capacitor formed by the second fixed electrode plate 31 and the movable electrode plate 21 (hereinafter, referred to as a “second capacitor”) based on the potential of the movable electrode plate 21 detected via the second fixed electrode plate 31. The capacitance C2 is detected.
[0029]
Here, the control unit (not shown) determines whether or not the capacitance difference ΔC between the capacitance C1 of the first capacitor and the capacitance C2 of the second capacitor is at a predetermined equilibrium position (neutral position). I do. When the capacitance difference ΔC is equal to or larger than a predetermined value, the connection between the adjustment electrode plate 112 of the capacitor having the larger capacitance (for example, the first capacitor) and the main body electrode plate 111 is cut off. Therefore, a laser is irradiated from above the glass substrate 1 to cut the connecting portion 11a. Thereby, the capacitance C1 of the first capacitor is reduced, and 2 to 4 adjustment electrode plates 112 are cut in accordance with the capacitance difference.
[0030]
The operation of the capacitor of the capacitance type acceleration sensor configured as described above is as follows.
When acceleration is externally applied to the detection unit 100 in a state where the capacitance-type acceleration sensor is attached to the object to be measured, the acceleration unit is supported at an equilibrium position by the elastic unit 22 due to the acceleration. The movable electrode plate 21 is displaced in the plate thickness direction while being restrained by the elastic portion 22. As a result, the capacitance C1 of the first capacitor and the capacitance C2 of the second capacitor increase and decrease with each other, and accordingly, ΔC, which is the difference between the two capacitances, changes. The acceleration of the object to be measured is calculated based on the capacitance difference.
[0031]
Although the configuration of the control unit is not shown, the control unit that operates as described above can be realized by a microcomputer or other hardware, or a DSP (Digital Signal Processor) or other software.
Various modifications are conceivable for the shape of the fixed electrode in the present invention.
For example, the capacitance of the capacitor may be reduced by forming the fixed electrode plates 11 and 31 in a mesh shape and cutting a part (adjustment portion) of the mesh.
[0032]
According to the capacitive acceleration sensor configured and operated as described above, the following excellent effects can be obtained.
[0033]
Since the first fixed electrode plate 11 and the second fixed electrode plate 31 are provided with the adjusting electrode plates 112 and 312 for adjusting the capacitance, when an error occurs in the value of the capacitance, The capacitance value can be easily adjusted by separating the adjusting electrode plates 112 and 312 of the fixed electrode plates 11 and 31 from the main body electrode plates 111 and 311. Therefore, more accurate physical quantity measurement can be performed.
[0034]
In addition, since the adjustment electrode plates 112 and 312 are configured by a plurality of adjustment electrode plates having known capacitances, the adjustment electrode plates can be selected according to the error, and a more accurate physical quantity can be obtained. A measurement can be made.
[0035]
Further, the silicon substrate 2 and the glass substrates 1 and 3 are anodically coupled such that the movable electrode plate 22 and the fixed electrode plates 11 and 31 face each other with a predetermined distance therebetween, and the movable electrode plate 22 and the fixed electrode plates 11 and 31 are joined together. , 31 are measured, and based on the measurement result, the connection between at least a part of the adjustment electrode plates 112, 312 and the main body electrode plates 111, 311 is cut by a laser. Since the physical quantity detector is assembled and manufactured, mechanical errors in the manufacturing process can be easily corrected mechanically after the physical quantity detector is assembled.
[0036]
As described above, the capacitive acceleration sensor to which the present invention is applied has been described, but the technical idea of the present invention is not limited to this. For example, the following can be said to be equivalent to the present invention.
[0037]
For example, a control unit (not shown) is realized by a chip-type microcomputer, and the realized microcomputer is incorporated in the detection unit 100, and acceleration and other physical quantities detected by the microcomputer are externally output by infrared rays or other radio. It may be configured as follows. In this case, it is preferable that the energy for driving the microcomputer and the energy necessary for outputting the detection result to the outside be supplied from outside by a microwave. With such a configuration, the capacitance type physical quantity sensor can be installed not only in the necessity of the lead wire L but also in a narrow place or a place in a bad environment.
[0038]
In addition to the acceleration, the design can be changed so as to detect the pressure and other physical quantities. This can be easily realized by configuring the movable electrode plate 21 to be displaced due to an external pressure or other physical quantity.
[0039]
Further, the capacitance type physical quantity sensor according to the present invention is applicable to an inclinometer. In this case, no getter is required because vacuum sealing is not performed.
[0040]
【The invention's effect】
According to the first aspect of the present invention, the fixed electrode plate is provided with the adjustment unit for adjusting the capacitance. Therefore, when an error occurs in the value of the capacitance, the adjustment unit of the fixed electrode plate is adjusted. The capacitance value can be easily adjusted by separating it from other parts. Therefore, more accurate physical quantity measurement can be performed.
[0041]
According to the second aspect of the present invention, it is needless to say that the same effect as that of the first aspect of the invention can be obtained. In particular, the adjusting section is constituted by a plurality of adjusting electrode plates having a known capacitance. Therefore, the adjustment electrode plate can be selected according to the error, and more accurate physical quantity measurement can be performed.
[0042]
According to the third aspect of the present invention, the base and the light-transmitting material are coupled to each other so that the movable electrode plate and the fixed electrode plate face each other with a predetermined distance therebetween, and are formed by the movable electrode plate and the fixed electrode plate. The capacitance of the capacitor to be measured is measured, based on the measurement result, since the connection between at least a part of the adjustment electrode plate and the main body is cut off by the laser, after assembling and manufacturing the physical quantity detector, It is possible to easily perform mechanical correction of an error generated in a manufacturing process.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view schematically showing a configuration of a detection unit of a capacitance type acceleration sensor.
FIG. 2 is a partial plan view showing a movable electrode plate and an elastic portion provided in a detection unit of the capacitance type acceleration sensor.
FIG. 3 is a schematic sectional view showing a detection unit of the capacitance type acceleration sensor.
FIG. 4 is a cross-sectional view showing a capacitance type acceleration sensor according to the related art.
[Explanation of symbols]
Reference Signs List 1 glass base 2 silicon base 3 glass base 11 first fixed electrode plate (fixed electrode plate)
20 body part 21 movable electrode plate (movable electrode plate)
22 elastic part 31 second fixed electrode plate (fixed electrode plate)
100 detection unit (physical quantity detector)
111, 311 Main unit electrode (main unit)
112, 312 Adjusting electrode plate (adjusting unit)
221 Elastic support member

Claims (3)

A movable electrode plate displaceably supported by an elastic portion,
A fixed electrode plate disposed at a position facing the movable electrode plate,
A displacement-adjustable physical quantity detector for detecting any physical quantity of the displacement, velocity, or acceleration of the measured object based on the capacitance of a capacitor formed by the movable electrode plate and the fixed electrode plate,
The fixed electrode plate is formed of a translucent material,
A physical quantity detector capable of adjusting a capacitance, wherein the fixed electrode plate is provided with a main body and an adjusting unit connected to the main body and adjusting an electrostatic capacity. 2. The physical quantity detector according to claim 1, wherein the physical quantity is adjustable.
The physical quantity detector capable of adjusting a capacitance, wherein the adjusting unit is configured by a plurality of adjusting electrodes having known capacitances. A method for manufacturing a physical quantity detector capable of adjusting a capacity according to claim 1 or 2,
Forming a movable electrode plate on the base;
Forming the fixed electrode plate on the translucent material;
Coupling the base and the translucent material such that the movable electrode plate and the fixed electrode plate face each other with a predetermined distance therebetween;
The capacitance of the capacitor formed by the movable electrode plate and the fixed electrode plate is measured, and based on the measurement result, at least a part of the adjustment unit of the fixed electrode plate is connected to the main body. Laser cutting process,
A method for manufacturing a physical quantity detector capable of adjusting a capacity, comprising:

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