JP2001194153A - Angular velocity sensor, acceleration sensor and method of manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for a step etching process and the influence of driving voltage. SOLUTION: This angular velocity sensor includes: a frame 106; a vibrating frame 104 disposed within the frame 106 and vibrated by a predetermined driving force; a weight part 101 disposed within the vibrating frame 104 for detecting angular velocity displaced in the direction of the Coriolis force, by Coriolis force perpendicular to the direction of the vibration, a composite beam 102 connecting the vibrating frame 104 and the weight part 101; and a vibrating beam 105 connecting the frame 106 to the vibrating frame 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor and an acceleration sensor used for, for example, controlling the attitude of a vehicle, calculating the direction of travel, and preventing hand shake of a hand camera.

[0002]

2. Description of the Related Art Various gyroscopes (hereinafter, referred to as gyroscopes) have been developed as sensors for detecting angular velocity. The types can be roughly classified into mechanical gyroscopes, optical fiber gyros, fluid gas rate gyros, and vibration gyros such as tuning forks.

In recent years, in response to demands for downsizing, power saving, and cost reduction of products, development of ultra-small angular velocity sensors formed by applying micromachining micromachining technology to materials such as single crystal silicon and quartz. Is also underway.

[0004] Most of angular velocity sensors using micromachines belong to vibrating gyroscopes. The principle of detection is as follows. When the vibrating weight rotates the weight about an axis perpendicular to the vibration direction, forces in the vibration direction and the rotation axis perpendicular to each other act on the weight. Detects the displacement of the weight in the force direction due to this force,
From that, the angular velocity is calculated.

This sensor has a driving force for exciting vibration,
A mechanism for detecting the displacement of the weight is required. When the material of the sensor is a piezoelectric body or a part provided with a piezoelectric body, a distortion generated by applying a voltage to the piezoelectric body is used for driving, and an electric charge generated by the distortion applied to the piezoelectric body is detected.
Other methods use magnetism or electrostatic force.

[0006] Among them, those using a piezoelectric body are difficult to perform fine processing when a bulk piezoelectric body is used. For example, when a piezoelectric body is formed on silicon, the formation itself requires a great deal of labor. . In the use of magnetism, the hurdles that must be overcome for practical use are high, such as the effect on peripheral circuits due to the use of magnets and the difficulty in forming highly efficient fine coils.

For these reasons, development of a vibrating micromachine gyro using a silicon wafer as a material and using electrostatic force for both driving and detection has reached a practical stage. Driving using an electrostatic force means applying a force of attracting parallel plate electrodes storing different charges to each other. Therefore, it is advantageous that the total area of the electrodes is larger.

On the other hand, in a parallel plate capacitor storing a fixed charge, a displacement is obtained by detecting a change in inter-electrode voltage due to a change in the inter-electrode distance.
Again, the larger the total area of the electrodes on the detection side, the more advantageous. In particular, since the displacement on the detection side is much smaller (two or three digits smaller) than the displacement of the drive vibration, higher precision processing and improved detection efficiency are required. In this type of micromachine angular velocity sensor, for example, a paper published by P. Greiff et al. (Silicon monolithic micromechanical g
yroscope, Transducers'99, P966-969) and a paper (MEMS'99) published by Murata Manufacturing in recent years. Also. An example is also described in Japanese Unexamined Patent Publication No. Hei 5-321576 “Angular velocity sensor”.

As described above, in the vibrating micromachine gyro, in order to increase the driving efficiency and the detection efficiency, it is necessary to increase the electrode area of each of the drive electrode for detection and the detection electrode for detection. Therefore, in order to use the entire surface of the weight as an electrode or to enhance space efficiency, a structure such as a comb shape, a ladder shape, or a fishbone is employed. In order to improve the efficiency, it is also important to reduce the distance between the electrodes as well as to increase the area of the electrodes and to carry out the processing of the configuration accuracy.

In order to meet these demands, reactive ion etching (hereinafter referred to as RIE), which is a semiconductor process and is a kind of plasma etching, is used recently. Ultra-fine processing by this technology makes it possible to produce a structure made of silicon with a pitch of several microns, and an angular velocity sensor having a main body of several mm square has been realized.

On the other hand, micromachine technology has been introduced in the acceleration sensor one step ahead of the angular velocity sensor. In conventional acceleration sensors, there are many cantilever beams, both-end supporting beams, and the like. In these methods, when an acceleration is applied to the weight, the amount of displacement of the weight due to the spring property of the beam is detected by a capacitance type (change in the distance between the capacitor electrodes). Since an acceleration sensor has a simpler structure than an angular velocity sensor, an example of an angular velocity sensor using RIE is rarely seen.

[0012]

SUMMARY OF THE INVENTION In a small sensor,
RIE processing is required to realize high-efficiency driving and detection. This technique enables fine etching with an accuracy of several microns. However, the amount of displacement on the detection side is very small, and when a comb-shaped electrode or the like is used as the detection electrode, a portion having a structure size of 2 to 3 μm is formed, and RIE involves considerable difficulty.

When the detection electrode is in the weight direction, it is free from the super-precision machining accuracy of a comb-shaped electrode or the like, but the weight moves in the thickness direction. In order to make the detected displacement as large as possible, it is necessary to reduce (ie, weaken) the spring constant in the thickness direction of the beam supporting the weight. In order to reduce the spring property, it is necessary to make the cross section of the beam thin and wide.

Therefore, it is necessary to form a beam having a thickness different from the thickness of the wafer by RIE, and to control the thickness accuracy with high accuracy. RIE can basically only etch the workpiece in the thickness direction.

Further, from the viewpoint of processing accuracy, the processing accuracy in the wafer surface depends on the mask accuracy, so that high accuracy can be realized. However, the accuracy in the depth direction is inferior to the in-plane accuracy due to temperature and plasma non-uniformity. It is relatively bad when compared.

Therefore, in order to form the above-mentioned beam by RIE, it is necessary to perform the processing in the thickness direction separately from the processing of the planar shape of the beam, and the number of processing steps involved is greatly increased. In addition, the control in the thickness direction by RIE has a relatively large error, and it is difficult to realize high-accuracy detection due to unevenness of the spring property. Therefore, it is difficult to achieve both cost reduction and high accuracy. I was

The present invention has been made in view of the above problems, and
It is an object of the present invention to provide an inexpensive and high-precision angular velocity sensor by IE and a method of manufacturing the same.

In order to ensure the accuracy of the angular velocity sensor, there is a problem that the drive signal affects the detection electrode. The detection system must detect a small change in capacitance of the capacitor, but since the drive electrode and the detection electrode are on the same wafer,
Part of the leakage current from the drive electrode flows into the detection electrode,
The charge amount of the capacitor configured in the detection unit fluctuates,
There is a problem that the detection accuracy of the angular velocity decreases.

The present invention has been made in view of the above problems, and has as its object to provide a high-precision angular velocity sensor which is hardly affected by a drive signal.

In the micromachine acceleration sensor,
It is composed of a cantilever beam or a support beam at both ends. In the case of a cantilever, the weight itself is also tilted due to the displacement of the weight, so that the detection unit is not a parallel plate capacitor, which causes a detection error. In addition, a detection error also occurs in the beam supported at both ends due to the occurrence of a tilt in the rotation direction about the beam center.

If the number of beams is increased to three or more to suppress these inclinations, step etching is performed on the flat wafer, and etching and an accompanying mask generation step are accompanied. Even if it is not only RIE, the etching accuracy in the thickness direction is worse than the in-plane accuracy. Therefore, when the number of beams increases, it becomes very difficult to keep the spring characteristics of the beams uniform. Therefore, there is a problem that it is difficult to achieve both cost reduction and high accuracy.

The present invention has been made in consideration of such a problem, and
It is an object of the present invention to provide an inexpensive and high-accuracy acceleration sensor by IE and a method of manufacturing the same.

[0023]

In order to achieve the above object, a first aspect of the present invention (corresponding to claim 1) is to use a fixed frame and a predetermined driving force arranged in the fixed frame. A vibrating frame that vibrates, disposed in the vibrating frame, is displaced in the direction of the Coriolis force by a Coriolis force orthogonal to the direction of the vibration, a weight portion for detecting an angular velocity, the vibrating frame, and the vibrating frame, The weight portion is connected to the weight portion, the weight portion has elasticity enough to detect the displacement caused by the Coriolis force, and has rigidity enough to prevent the influence of the vibration caused by the driving force. 1 that connects the fixed frame and the vibrating frame to each other. The vibrating frame has elasticity enough to efficiently vibrate the vibrating frame, and the Coriolis An angular velocity sensor being characterized in that a second beam structure having a rigidity enough to prevent the affect of due displaced.

The second invention (corresponding to claim 2)
Is characterized in that the fixed frame, the vibrating frame, the weight, the first beam structure, and the second beam structure have substantially the same thickness in the direction of the Coriolis force. This is the present invention.

The third invention (corresponding to claim 3)
The first beam structure includes a first sub beam connected to the vibration frame, a second sub beam connected to the weight portion, the first sub beam, and the second sub beam. And a third sub-beam that connects the first and second sub-beams, wherein the first and second sub-beams have elasticity with respect to the Coriolis force, and the third sub-beam has rigidity with respect to the driving force. The present invention is characterized in that:

The fourth invention (corresponding to claim 4)
The present invention is characterized in that the first and second sub-beams are support beams at both ends.

The fifth invention (corresponding to claim 6)
The first beam structure is constituted by a pair of cantilevered sub beams, and a distance between two central portions of the pair of sub beams fixed to the same side is equal to the vibration frame. The present invention is characterized in that the distance is larger than the distance between the two central portions with the weight portion.

The sixth invention (corresponding to claim 8)
According to the present invention, the rigidity and elasticity of the first to fifth sub beams are set by the width of the angular velocity sensor in the surface direction of the sub beam.

A seventh aspect of the present invention (corresponding to claim 9)
Further includes a substrate having a first drive electrode, a first detection electrode, and a ground electrode facing at least the vibration frame and the weight portion, and the vibration frame partially includes a second drive electrode. And the driving force is obtained from the first driving electrode and the second driving electrode as an electrostatic force. The weight portion further includes a second detection electrode, and the weight portion further includes a second detection electrode. The Coriolis force is detected by a change in capacitance between two detection electrodes, and the ground electrode is provided between the first drive electrode and the first detection electrode. The present invention is characterized in that it is arranged so as to surround the periphery of the electrode.

An eighth aspect of the present invention (corresponding to claim 10)
A fixed frame, disposed in the fixed frame, displaced in the direction of the acceleration by a predetermined acceleration, a weight portion for detecting acceleration, and connecting the fixed frame and the weight portion, A third beam structure having an elasticity enough to detect a displacement caused by the force given by the acceleration with respect to the weight portion, wherein the third beam structure has a sixth sub-structure connected to the vibration frame; A beam, a seventh sub-beam connected to the weight portion, and an eighth sub-beam connecting the sixth sub-beam and the seventh sub-beam, wherein the fixed frame, the weight portion, The third beam structure is an acceleration sensor having substantially the same thickness in the direction of the acceleration.

The ninth invention (corresponding to claim 11)
The present invention is characterized in that the sixth and seventh sub-beams are support beams at both ends.

According to a tenth aspect of the present invention (corresponding to claim 13), a fixed frame and a predetermined acceleration disposed in the fixed frame displace in the direction of the acceleration.
A weight for detecting acceleration, a fourth beam connecting the fixed frame and the weight, and having a degree of elasticity with respect to the weight that can detect a displacement caused by a force given by the acceleration; And wherein the fourth beam structure comprises a pair of cantilevered sub-beams, and is fixed to the same side of the pair of sub-beams. The distance between the two central portions is greater than the distance between the two central portions between the vibration frame and the weight portion, and the fixed frame, the weight portion, and the fourth beam structure And an acceleration sensor having substantially the same thickness in the direction of the acceleration.

An eleventh aspect of the present invention (corresponding to claim 16) is the method of manufacturing an angular velocity sensor according to the present invention, wherein the silicon substrate is subjected to reactive ion etching (RI) once.
E), the fixed frame, the vibration frame,
A method of manufacturing an angular velocity sensor, comprising a step of forming the weight portion, the first beam structure, and the second beam structure.

A twelfth aspect of the present invention (corresponding to claim 17) is the method of manufacturing an acceleration sensor according to the present invention, wherein the silicon substrate is subjected to one-time reactive ion etching (RI).
E), the fixed frame, the vibration frame,
A method of manufacturing an acceleration sensor, comprising a step of forming the weight portion, the third beam structure, or the fourth beam structure.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) An angular velocity sensor composed of single crystal silicon and glass according to Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 1, a sensor body 100 processed by etching a silicon wafer
At the center is a weight portion 101 that is displaced by Coriolis force generated by rotational motion. The weight 101 is attached to the vibration frame 104 by four sets of composite beams 102.

The structure of the composite beam 102 is as shown in FIG.
Right-angle beams 202 and 203 are attached to both ends of the connecting beam 201, respectively.

A drive electrode 103 is mounted inside the vibration frame 104 of FIG. 1 to vibrate the entire vibration frame in the direction of the arrow. Weight part 101 and drive electrode 103
Between them, a groove 107 is dug all over the outer periphery of the weight portion 101. The fixed frame 10 is provided outside the vibration frame 104.
6, the vibration frame 104 is supported by a fixed frame 106 via a driving beam 105.

The glass substrate 1 faces the sensor body 100.
20 are placed. The glass substrate 120 is etched with hydrofluoric acid, and the sensor body 100 is provided with an etching surface 121 at a constant interval.
The drive electrode 1 made of a conductive thin film is provided on the etching surface 121.
23, 124, 125, detection electrode 122, ground electrode 12
8 are formed. The joint surface 129 between the fixed frame 106 of the sensor body 100 and the glass substrate is fixed by anodic bonding.

Next, the operation of the angular velocity sensor according to the first embodiment of the present invention will be described. The silicon wafer of the sensor body 100 is a conductor since impurities such as bromine are diffused in the silicon wafer, and its potential is GND. On the other hand, a bias voltage is applied to the drive electrodes 123, 124, and 125 formed on the glass substrate 120 from the external power supply circuit (not shown) via the bonding pads 135, so that an AC voltage having a positive potential is always provided. Is applied.

A drive electrode 103 on the sensor body 100 side;
The positional relationship between the drive electrodes 124 and 125 on the glass substrate side is as follows.
As shown in section A (section AA in FIG. 1) of FIG. 3, they are arranged at a constant pitch from each other, and the drive electrode 103 on the sensor body side and the drive electrodes 124 and 125 on the glass substrate side.
Are opposed by a １ ／ pitch.

Here, the same voltage signal is applied to the drive electrodes 123 and 125 (not shown in FIG. 3),
, A voltage signal whose phase is different from that of the drive electrodes 123 and 125 by 180 degrees is applied. Therefore, attractive forces 130 and 131 due to the electrostatic force are generated alternately between the sensor drive electrode 103 having the potential 0 and the vibration frame 104 including the weight portion 101.
The whole vibrates in the direction D of the coordinate axis 110.

At this time, if the entire sensor rotates in the Ω direction of the coordinate axis 110, Coriolis force acts in the S direction. The drive beam 105 supporting the vibration frame 106 has a degree of freedom in the direction D of the coordinate axis 110, but has high rigidity in the direction S, so that displacement in the direction S due to Coriolis force can be substantially ignored.

Next, the movement of the weight 101 will be described. The weight portion 101 is connected to the connecting beam 201 shown in FIG.
It is supported from four directions by a composite beam 102 having a structure in which 2, 203 are combined. As a whole, the four composite beams 102 have high rigidity in the direction parallel to the upper surface of the weight portion 101, and the relative displacement in the D direction to the vibration frame 104 due to the application of the vibration in the D direction is substantially negligible. Further, regarding the resonance frequency of the structure formed by the weight portion 101 and the composite beam 102, the resonance frequency in the D direction is higher than twice the S direction, so that the vibration in the S direction is not induced by the vibration in the D direction.

Here, consider the case where Coriolis force in the S direction acts on the weight portion 101. The composite beam 102 has low rigidity in the S direction, and deforms as shown in FIG. 4 when Coriolis force acts. At this time, since the four sets of composite beams 102 are deformed by the same amount in the same direction, the weight portion 101 moves in parallel in the direction in which Coriolis force acts. Since the sensor main body 101 is connected to GND by a conductive silicon wafer, as shown in a cross section B (BB cross section in FIG. 1) of the weight portion 101 and the detection electrode 1
22 forms a plate capacitor.

When the weight 101 moves in parallel due to Coriolis force, the distance between the detection electrode 122 and the weight 101 changes, and the capacitance of the capacitor changes. The capacitance of this capacitor is C-
The voltage is converted into a voltage by a V conversion circuit (not shown), and the Coriolis force is detected. The principle of detecting the capacitance of a capacitor is V = Q
The relationship between the voltage / charge amount / capacity of the capacitor of / C is used. That is, when the amount of charge stored in the capacitor is considered to be constant, the voltage across the capacitor is inversely proportional to the capacitance.

Therefore, it is very important that the amount of charge stored in the capacitor is constant, and it is necessary to eliminate as much as possible noise from the adjacent drive electrodes 123, 124, and 125. As a configuration for that,
Detection electrode 123 and detection electrode extraction pad 1 on substrate side
27, the periphery of the lead portion 126 connecting them is the ground electrode 12
8 are arranged. By being surrounded by the ground electrode 128, the leakage current from the drive electrodes 123, 124, and 125 is absorbed by the low impedance ground electrode 128,
Direct mixing into the detection electrode 122 can be prevented.

The path of the next largest leakage current is mixing through the sensor body 100. Since the sensor body 100 is made of a conductive silicon wafer, the input impedance is not as low as metal. Therefore, a groove 107 is provided around the detection electrode 101 on the sensor body side to isolate the drive electrode 102 from the detection electrode 101. Further, the contact between the vibration frame 104 and the detection electrode 101 was limited to only the cross-sectional area of the composite beam portion 102. The cross-sectional dimensions of the composite beam 102 of this embodiment are as follows:
Since the width is as small as 10 μm and the thickness is 50 μm, the electric resistance of the composite beam portion 102 is extremely high. Therefore, the signal flowing from the glass substrate-side drive electrodes 123, 124, and 125 to the sensor body-side drive electrode 103 flows to the ground source having low impedance, and hardly flows into the detection electrode 101, thus affecting the detection vibration. Is virtually negligible.

As described above, the substrate-side detection electrode 122, the lead wire portion 126 connected to the detection electrode 122, and the terminal extraction pad 127
Is surrounded by a ground electrode 128, and a groove 107 is further provided around the detection electrode 101 on the sensor body side to form a drive electrode 10.
3 and the connection with the vibration frame 104 is made only by the composite beam 102 having a small active section, it is possible to configure a high-precision angular velocity sensor having substantially no influence of the driving voltage.

Next, a manufacturing process of the angular velocity sensor according to the present embodiment will be described. One side of the glass substrate 120 is etched with hydrogen fluoride to form an etched surface 121.
A metal thin film is formed on the etching surface 121. In this embodiment, Cr / Au is used. A resist is applied on the metal thin film, and photolithography is performed to form electrode patterns (drive electrodes 123, 124, 125, detection electrodes 122, lead wires 126, etc.) using the metal thin film. Next, processing of the sensor main body 100 is performed. SOI on the sensor body
(Silicon On Insulator) is used. In this embodiment, an active layer having a thickness of 50 μm, an insulating layer having a thickness of 2 μm, and a supporting layer having a thickness of 400 μm was used.

First, anodic bonding is performed on the bonding surface 129 between the active layer and the glass substrate 120. This is at high temperatures (350-40
0 ° C) and high voltage (500-1000) on silicon and glass.
V) is applied to connect the silicon surface and the glass surface firmly. Second, the support layer of the SOI is entirely peeled off to expose the SiO2 surface as an insulating layer. For the support layer peeling, wet etching with a strong alkali or RIE (reactive ion etching) is used.

Third, the exposed SiO 2 surface is removed by etching with hydrogen fluoride. Fourth, a resist is applied and photolithography is performed, and patterning of the drive electrode 103, the composite beam 102, the weight 101, and the like is performed with the resist.

Fifth, Si is etched by RIE along the patterning of the resist. What is RIE?
This is a technique in which a plasma for etching a silicon is alternately generated with a plasma for forming a deposition layer on Si, and a voltage is applied perpendicularly to a processing surface, so that an exposed Si portion is dug vertically. Since the RIE basically digs uniformly all over in the vertical direction, the etching depth cannot be changed obliquely or partially. When the etching depth is partially changed (step etching), the shallowly etched portion is protected by a resist, and the deep portion is first etched by the thickness of the shallow portion. Therefore, the wafer is once taken out, the resist in the shallow portion is removed, and both the deep portion and the shallow portion are etched to a predetermined depth.

As described above, when the step etching is performed, two RIE steps and the removal of the resist, recoating, and photolithography between the two steps are required, which greatly increases the number of steps. But,
Normally, to form a soft spring that is soft in the direction perpendicular to the wafer surface and hard in parallel to the wafer surface, a leaf spring that is thin in the wafer thickness direction and wide in the surface direction is required.

However, the thickness of the composite spring of this embodiment is the same as the thickness of the wafer, does not require multi-stage etching, and can be formed by one RIE. That is, by using three or more sets of composite beams as in the present embodiment (four sets in this example), a spring that is soft in the direction perpendicular to the wafer surface and hard in parallel with the wafer surface can be formed by one RIE. And a highly accurate sensor can be provided at low cost.

(Embodiment 2) An acceleration sensor made of single-crystal silicon and glass, which is Embodiment 2 of the present invention, will be described with reference to FIG. In FIG. 7, a sensor body 300 is made of a conductive single crystal silicon wafer, and has a weight 301 for detecting acceleration in the S direction in the center.
There is. The weight 301 is supported by the frame 302 via the four sets of composite beams 102 similar to those described in the first embodiment.

The glass substrate 3 facing the sensor body 300
06 is provided, and anodically bonded to the frame 302 and the bonding surface 303. Etched surface 3 on glass substrate 306
A detection electrode 305 is attached to a position of the surface facing the weight portion 301, and a signal is extracted from a terminal extraction pad 307 via a lead wire 308.

Next, the operation of the acceleration sensor according to the present embodiment will be described. The basic configuration of the acceleration sensor according to the present embodiment is the same as the detection system structure inside the vibration frame of the angular velocity sensor according to the first embodiment.

When an acceleration is applied in the S direction in FIG. 7, the weight 301 is displaced in the acceleration direction. At this time, the weight 30
1 and the detection electrode 305, the distance between the electrodes of the flat plate capacitor changes, so that the capacitance of the capacitor changes.
As described in Embodiment 1, the charge is kept constant,
From the relationship of V = Q / C, the displacement amount of the weight portion 301 is converted into a voltage.

The acceleration sensor according to the present embodiment is different from a conventional configuration using a normal cantilever beam or two ends supporting beams.
Since the inclination is substantially negligible because of the displacement of the weight, the linearity between the displacement of the weight 301 and the output voltage is excellent.

Further, the weight 301 is provided by a cantilever beam or a support beam at both ends.
In order to soften the beam in the displacement direction, multi-stage etching is required, and a large number of steps are required as described in the first embodiment. However, the composite beam 102 in the present embodiment
Since the beam thickness is equal to the wafer thickness, it can be formed by one etching such as RIE. Therefore, a high-precision angular velocity sensor can be provided at low cost.

(Embodiment 3) A composite beam shape according to Embodiment 3 of the present invention will be described with reference to FIG. In Embodiments 1 and 2, a composite beam as shown in FIG. 2 is used.

On the other hand, in this embodiment, as shown in FIG.
The beams 205 and 206 are provided at both ends of the connecting beam 201, and the slits 207 and 208 are provided next to each other. Even in such a composite beam, deformation similar to that of the beams 202 and 203 in FIG. 4 occurs, so that the same effect can be obtained even if the composite beam of the angular velocity sensor and the acceleration sensor of the first and second embodiments is used instead.

(Embodiment 4) A composite beam shape according to Embodiment 4 of the present invention will be described with reference to FIG. In Embodiments 1 and 2, a composite beam as shown in FIG. 2 is used.

On the other hand, in this embodiment, as shown in FIG.
1 and 402, beams 4 at both ends of the connecting beams 401 and 402.
03,405,404,406. This is exactly the structure in which the composite beam of FIG.

Even with such a composite beam, the beam 202, FIG.
A deformation similar to 203 occurs. Furthermore, since the interval between the two beams on the left and right can be freely set, the stability with respect to the inclination of the weight portion 101 can be improved. Therefore, even if it is used in place of the composite beam of the angular velocity sensor and the acceleration sensor of the first and second embodiments, it works in exactly the same way, and an angular velocity sensor and an acceleration sensor with more stable output signals can be realized.

Note that the first and third beam structures of the present invention correspond to the composite beam of the embodiment, and the second beam structure of the present invention corresponds to the vibrating beam and the like of the embodiment. The first, second, sixth and seventh sub beams of the present invention correspond to the beams of the embodiment, and the third and eighth sub beams of the present invention It corresponds to the connecting beam of the form.

[0068]

As described above, according to the present invention, it is possible to form an angular velocity sensor having high noise resistance and high accuracy and an acceleration sensor having excellent output linearity without using step etching. There is an effect that sensors and acceleration sensors can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view of an angular velocity sensor according to a first embodiment.

FIG. 2 is an enlarged view of a composite beam of the angular velocity sensor according to the first embodiment.

FIG. 3 is a cross-sectional view of the angular velocity sensor according to the first embodiment.

FIG. 4 is an enlarged view of a composite beam of the angular velocity sensor according to the first embodiment (when deformed).

FIG. 5 is an enlarged view of a composite beam of the angular velocity sensor according to the third embodiment.

FIG. 6 is an enlarged view of a composite beam of the angular velocity sensor according to the fourth embodiment.

FIG. 7 is a perspective view of an acceleration sensor according to a second embodiment.

[Explanation of symbols]

100, 300 Sensor body 101, 301 Weight section 102 Composite beam 103 Drive electrode (sensor body side) 104 Vibration frame 105 Drive beam 106, 302 Frame 107 Groove section 110 Coordinate axis 120, 306 Glass substrate 121, 304 Etched surface 122, 205 Detection electrode 123, 124, 125 Drive electrode (glass substrate side) 126, 308 Lead wire part 127, 307 Terminal extraction pad 128 Ground electrode 129, 303 Joining surface 201, 401, 402 Connecting beam 202, 203, 205, 206, 403, 304 , 4
05, 406 beams

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F105 AA01 AA08 BB01 BB03 BB14 BB15 CC04 CD03 CD05 CD13 4M112 AA02 BA07 CA24 CA26 CA36 DA03 DA18 EA03 EA13

Claims (17)

[Claims] A fixed frame, a vibration frame disposed in the fixed frame, which vibrates with a predetermined driving force, and a Coriolis force disposed in the vibration frame, the Coriolis force being orthogonal to a direction of the vibration. Displaced in the direction of the Coriolis force, a weight for detecting angular velocity, and connecting the vibrating frame and the weight, the elasticity of the weight is such that the displacement caused by the Coriolis force can be detected. A first beam structure having such a rigidity as to prevent the influence of vibration caused by the driving force from being exerted, and connecting the fixed frame and the vibration frame to the vibration frame. A second beam structure having an elasticity enough to efficiently vibrate and a rigidity enough to prevent the influence of the displacement caused by the Coriolis force. An angular velocity sensor, characterized in that the. 2. The fixed frame, the vibration frame, the weight portion, the first beam structure, and the second beam structure,
The angular velocity sensor according to claim 1, wherein the sensor has substantially the same thickness in the direction of the Coriolis force. 3. The first beam structure includes: a first sub beam connected to the vibration frame; a second sub beam connected to the weight portion; a first sub beam connected to the weight portion; A third sub-beam for connecting to the sub-beam, wherein the first and second sub-beams have elasticity with respect to the Coriolis force, and the third sub-beam is rigid with respect to the driving force. The angular velocity sensor according to claim 1, further comprising: 4. The angular velocity sensor according to claim 3, wherein the first and second sub beams are both-end supporting beams. 5. The third sub beam includes the first and second beams.
The angular velocity sensor according to claim 4, wherein the centers of the sub beams are connected to each other. 6. The first beam structure is constituted by a pair of cantilevered sub-beams, and a distance between two central portions of the pair of sub-beams fixed to the same side is the same. The angular velocity sensor according to claim 1, wherein the distance is larger than a distance between two central portions between the vibration frame and the weight portion. 7. The second beam structure, wherein a fourth sub-beam having a configuration extending in a direction perpendicular to the driving force direction, and a fifth sub-beam connected to a central portion of the fourth sub-beam. The angular velocity sensor according to any one of claims 1 to 6, comprising a sub beam. 8. The method according to claim 3, wherein the rigidity and elasticity of the first to fifth sub-beams are set by the width of the angular velocity sensor in the surface direction of the sub-beams. An angular velocity sensor according to any one of the above. 9. A substrate having a first drive electrode, a first detection electrode, and a ground electrode facing at least the vibrating frame and the weight portion, wherein the vibrating frame has a second part on a part thereof. A driving electrode, wherein the driving force is obtained as an electrostatic force from the first driving electrode and the second driving electrode, the weight portion further includes a second detection electrode, and the first detection Detecting the Coriolis force by a change in capacitance between an electrode and a second detection electrode, wherein the ground electrode is disposed between the first drive electrode and the first detection electrode. 9. The device according to claim 1, wherein said first detection electrode is arranged so as to surround said first detection electrode.
The angular velocity sensor according to any one of the above. 10. A fixed frame, a weight portion arranged in the fixed frame, which is displaced in a direction of the acceleration by a predetermined acceleration, for detecting an acceleration, and the fixed frame and the weight portion are connected to each other. A third beam structure having an elasticity enough to detect a displacement caused by the force given by the acceleration with respect to the weight portion, wherein the third beam structure is connected to the vibration frame. 6; a seventh sub-beam connected to the weight portion; and an eighth sub-beam connecting the sixth sub-beam and the seventh sub-beam. The weight portion and the third beam structure,
An acceleration sensor having substantially the same thickness in the direction of the acceleration. 11. The acceleration sensor according to claim 10, wherein the sixth and seventh sub beams are both-end supporting beams. 12. The acceleration sensor according to claim 11, wherein the eighth sub-beam connects the centers of the sixth and seventh sub-beams, respectively. 13. A fixed frame, a weight portion arranged in the fixed frame, which is displaced in a direction of the acceleration by a predetermined acceleration, for detecting an acceleration, and connects the fixed frame and the weight portion. And a fourth beam structure having an elasticity enough to detect a displacement caused by the force given by the acceleration with respect to the weight portion, wherein the fourth The beam structure is constituted by a pair of cantilevered sub beams, and a distance between two central portions of the pair of sub beams fixed to the same side is a distance between the vibration frame and the weight portion. The fixed frame, the weight portion, and the fourth beam structure,
An acceleration sensor having substantially the same thickness in the direction of the acceleration. 14. The angular velocity sensor according to claim 1, wherein the material is silicon. 15. The acceleration sensor according to claim 10, wherein the material is silicon. 16. The method of manufacturing an angular velocity sensor according to claim 1, wherein the silicon substrate is subjected to a single reactive ion etching (RI).
E), the fixed frame, the vibration frame,
A method of manufacturing an angular velocity sensor, comprising a step of forming the weight portion, the first beam structure, and the second beam structure. 17. The method for manufacturing an acceleration sensor according to claim 10, wherein the silicon substrate is subjected to one-time reactive ion etching (RI).
E), the fixed frame, the vibration frame,
A method of manufacturing an acceleration sensor, comprising a step of forming the weight portion, the third beam structure, or the fourth beam structure.