JPH09166441A - Vibrating gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vibrating gyro in which the vibrating amplitude of a vibrating body is made large and which prevents the damage of a support part by making the thickness in the length direction and that in a direction at a right angle to the length direction of the support part equal to each other and making the thickness in the up-and-down direction of an intermediate part thin. SOLUTION: In a sensor chip 1, a semiconductor substrate is etched and worked anisotropically, a vibrating body 2, a frame part 3 and support parts 4 are constituted integrally, and a piezoelectric element 5 for drive is vapor-deposited and formed in the central part on the surface of the vibrating body 2. At this time, every support part 4 is constituted in such a way that its thickness in the length direction and in a direction at a right angle to the length direction is made equal to each other and that the thickness in the up-and-down direction of an intermediate part excluding a coupling part with reference to the vibrating body 2 and the frame part 3 is made extremely thin. Thereby, the vibrating amplitude in the Z-direction of the vibrating body 2 and that in the Y-axis direction in which the Coriolis force is generated can be made large. In addition, an upper lid and a lower lid in which recessed part is formed in a depth suppressing the displacement of support part 4 are bonded to the chip 1. Thereby, even when an excessive mechanical stress is applied to the vibrating body 2, it is possible to prevent the damage of support part 4 without disturbing its vibration largely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating gyro, and more particularly to a sensor chip including a vibrating body, a frame portion, and a supporting portion connecting the vibrating body and the frame portion by processing a semiconductor substrate by anisotropic etching. The present invention relates to a vibration gyro equipped with.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 4 is a diagram illustrating a sensor chip of a vibration gyro formed of a semiconductor, and FIG. 5 is a diagram showing a cross section taken along line AA of FIG. In FIG. 4, reference numeral 1 indicates a sensor chip of a vibration gyro configured by processing a semiconductor substrate. The sensor chip 1 includes a vibrating body 2, a frame portion 3, and a support portion 4 connecting the vibrating body 2 and the frame portion 3. In FIG. 4, the vibrating body 2 is supported by the supporting portion 4 at two positions in the middle thereof. The position where the support portion 4 is formed is near the node of vibration of the vibrating body 2. In this sensor chip 1, the vibration body 2, the frame portion 3 and the support portion 4 are integrally formed by anisotropically etching a semiconductor substrate. For example, a silicon wafer having a plane orientation (100) is used as the semiconductor substrate, and a (111) plane is used as the etching surface.

The cross-sectional shape of the vibrating body 2 in FIG. 5 is hexagonal, but this shape can also be triangular or pentagonal. A driving piezoelectric element 5 is formed at the center of the upper surface of the vibrating body 2. The driving piezoelectric element 5 is formed by sputtering or vapor-depositing lead zircon titanate (PZT), zinc oxide (ZnO) and other piezoelectric materials. Piezoelectric elements for detection 6a and 6b are formed in the central portions of the slopes on both sides of the vibrating body 2. This detecting piezoelectric element 6
Similarly to the driving piezoelectric element 5, a and 6b are also formed by sputtering or vapor depositing lead zirconate titanate (PZT), zinc oxide (ZnO) and other piezoelectric materials. After the driving piezoelectric element 5 and the detecting piezoelectric element 6 are formed on the surface of the vibrating body 2 by sputtering or vapor deposition, the driving piezoelectric element electrode 51 is formed on the entire surface of the driving piezoelectric element 5 by sputtering or vapor deposition. In addition, the detection piezoelectric element electrode 61 is formed on the entire surface of the detection piezoelectric element 6. The semiconductor substrate itself that constitutes the sensor chip 1 is used as the counter electrode of the driving piezoelectric element electrode 51 and the detecting piezoelectric element electrode 61.

Driving piezoelectric element electrode 5 of driving piezoelectric element 5
When a drive signal is applied between 1 and the semiconductor substrate to drive the drive piezoelectric element 5, the drive piezoelectric element 5 vibrates and drives. When a drive signal is applied between the drive piezoelectric element electrode 51 and the semiconductor substrate, the drive piezoelectric element 5 is configured to bend and vibrate in the Z-axis direction. When the driving piezoelectric element 5 flexurally vibrates in the Z-axis direction, the vibrating body 2 receives a force in the Z-axis direction. Due to this, the vibrating body 2 flexurally vibrates in the Z-axis direction with the support portion 4 as a node. Arrive The drive signal is assumed to have a natural frequency in the drive direction of the vibrating body 2. A self-excited oscillation circuit can be adopted as the drive signal source.
When the vibrating body 2 is driven and vibrated, a strain corresponding to the driving vibration is generated in the vibrating body 2, and a voltage output corresponding to the magnitude and frequency of the strain is generated in the detection piezoelectric element 6.

Here, when the angular velocity about the X axis, which is the input axis, is input while the vibrating body 2 is vibrating in the Z axis direction,
A Coriolis force is generated in the Y-axis direction, and a force in the Y-axis direction acts on the vibrating body 2. The output voltage of the detecting piezoelectric element 6 changes from the position where the vibrating body 2 vibrates due to the Coriolis force. In this case, the output of one of the detection piezoelectric elements 6a and 6b increases, while the output of the other detection piezoelectric element decreases. By measuring the amount of change in the output of either one of the detecting piezoelectric elements 6 or the amount of change in the differential output of both outputs, the input angular velocity about the X axis, which is the input shaft, can be detected.

[0006]

In the vibrating gyroscope described above, the vibrating body 2 is located near the nodal point of the vibrating frame 3
It is supported by the support portion 4 as an attachment point for the, and does not suppress the vibration of the vibrating body 2. However, the vibration amplitude of the vibrating body 2 is not so large in general, and is also influenced by the cross-sectional shape and size of the support portion 4 that supports the vibrating body 2. In the conventional example of the vibration gyro, the cross-sectional shape of the support portion 4 is, for example, a hexagon, and the thickness thereof is about ½ of the thickness of the frame portion 3, which limits the vibration of the vibrating body 2. It was found that the vibration was suppressed.

According to the present invention, the supporting portion 4 for supporting the vibrating body 2 is provided.
The vibration gyro is provided in which the amplitude of the vibration of the vibrating body 2 is increased by appropriately setting the cross-sectional shape dimension thereof and the supporting portion 4 is not damaged.

[0008]

A vibration is provided with a sensor chip 1 including a vibrating body 2, a frame portion 3, and a supporting portion 4 connecting the vibrating body and the frame portion by processing a semiconductor substrate by anisotropic etching. Support part 4 in the gyro
Has the same thickness in the direction orthogonal to the longitudinal direction thereof, and the vertical thickness of the intermediate portion excluding the coupling portion 41 to the vibrating body 2 and the frame portion 3 is extremely thin.

Then, the frame portion 82 or 92 is formed by forming the concave portion 81 or 91 in the plate member having the same shape and size as the frame portion 3 of the sensor chip 1, and the concave portion 81 or 9 is formed.
The depth of 1 does not hinder the vibration of the vibrating body 2 and is set to a depth that suppresses the displacement of the support portion 4 when an excessive mechanical stress is applied to the vibrating body 2 and the upper lid 8 of the same type as this. A vibration gyro having the lower lid 9 joined to the frame portion 3 was constructed.

Further, although there is a concave portion for suppressing the displacement of the support portion 4 in the area corresponding to the vibration node of the vibrating body 2 which is the area where the support portion 4 is located, it corresponds to the antinode of the vibration of the vibrating body 2. The area to be cut is the vibrating body 2 as the punching through portion 83 or 93.
A vibration gyro with minimal vibration suppression was constructed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of a sensor chip of a vibrating gyroscope according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. Reference numeral 1 denotes a sensor chip of a vibration gyro configured by processing a semiconductor substrate. The sensor chip 1 includes a vibrating body 2, a frame portion 3, and a support portion 4 connecting the vibrating body 2 and the frame portion 3. The vibrating body 2 is supported by the supporting portion 4 at two places in the middle thereof. The position where the support portion 4 is formed is near the node of vibration of the vibrating body 2. The sensor chip 1 includes a vibrating body 2, which is obtained by anisotropically etching a semiconductor substrate.
The frame portion 3 and the support portion 4 are integrally configured. The cross-sectional shape of the vibrator 2 is hexagonal, but this shape is 3
It may be a polygon or a pentagon. A driving piezoelectric element 5 is formed at the center of the upper surface of the vibrating body 2. Piezoelectric elements for detection 6a and 6b are provided at the center of the slopes on both sides of the vibrating body 2.
Is formed. After the driving piezoelectric element 5 and the detecting piezoelectric element 6 are formed on the surface of the vibrating body 2 by sputtering or vapor deposition, the driving piezoelectric element electrode 51 is formed on the entire surface of the driving piezoelectric element 5 by sputtering or vapor deposition. In addition, the detection piezoelectric element electrode 61 is formed on the entire surface of the detection piezoelectric element 6. The semiconductor substrate itself that constitutes the sensor chip 1 is used as the counter electrode of the driving piezoelectric element electrode 51 and the detecting piezoelectric element electrode 61. Here, the support portion 4 of the sensor chip 1 has the same thickness in the direction orthogonal to its longitudinal direction, and the vertical thickness of the intermediate portion excluding the coupling portion 41 with respect to the vibrating body 2 and the frame portion 3 is extremely small. I made it thin.

Driving piezoelectric element 5 of driving piezoelectric element 5
When a drive signal is applied between 1 and the semiconductor substrate to drive the drive piezoelectric element 5, the drive piezoelectric element 5 vibrates and drives. When a drive signal is applied between the drive piezoelectric element electrode 51 and the semiconductor substrate, the drive piezoelectric element 5 is configured to bend and vibrate in the Z-axis direction. When the driving piezoelectric element 5 flexurally vibrates in the Z-axis direction, the vibrating body 2 receives a force in the Z-axis direction. Due to this, the vibrating body 2 flexurally vibrates in the Z-axis direction with the support portion 4 as a node. Arrive A self-excited oscillation circuit can be adopted as the drive signal source. When the vibrating body 2 is driven and vibrated, a strain corresponding to the driving vibration is generated in the vibrating body 2, and a voltage output corresponding to the magnitude and frequency of the strain is generated in the detection piezoelectric element 6. As described above, the support portion 4 of the sensor chip 1 has the same thickness in the direction orthogonal to the length direction, and the vertical thickness of the intermediate portion excluding the coupling portion to the vibrating body 2 and the frame portion 3 is maximized. With a thin structure, the vibration amplitude of the vibrating body 2 in the Z-axis direction and the vibration amplitude of the Y-axis direction in which the Coriolis force is generated can be increased.

When the angular velocity about the X axis, which is the input axis, is input while the vibrating body 2 is vibrating in the Z axis direction,
A Coriolis force is generated in the Y-axis direction, and a force in the Y-axis direction acts on the vibrating body 2. The output voltage of the detecting piezoelectric element 6 changes from the position where the vibrating body 2 vibrates due to the Coriolis force. In this case, the output of one of the detection piezoelectric elements 6a and 6b increases, while the output of the other detection piezoelectric element decreases. By measuring the amount of change in the output of either one of the detecting piezoelectric elements 6 or the amount of change in the differential output of both outputs, the input angular velocity about the X axis, which is the input shaft, can be detected.

As described above, the thickness of the supporting portion 4 is made equal in the direction orthogonal to the length direction as described above, and the vibrating body 2 is provided.
By making the vertical thickness of the intermediate portion excluding the joint portion with respect to the frame portion 3 extremely thin, the vibration amplitude of the vibrating body 2 in the Z-axis direction and the vibration amplitude of the Y-axis direction in which the Coriolis force is generated can be reduced. It is possible to increase the accuracy and improve the accuracy of detecting the input angular velocity. However, this means that the mechanical strength of the supporting portion 4 is weakened to some extent as compared with the conventional example, and the mechanical stress applied to the supporting portion 4 increases conversely as compared with the conventional example. 4 means there is an increased risk of damage. That is, when an excessive acceleration is applied to the vibration gyro, the supporting portion 4 is largely deformed, which causes damage.

Here, an upper lid and a lower lid that suppress the displacement of the support portion 4 are joined to the sensor chip 1 without greatly disturbing the vibration of the vibrating body 2 when an excessive mechanical stress is applied to the vibrating body 2. Adopt a configuration. This will be described with reference to FIG. FIG. 3A is a plan view showing the inside of the upper lid 8 and the lower lid 9. The upper lid 8 and the lower lid 9 have the same shape. In these lids, a frame portion 82 or 92 is formed by forming a recess 81 or 91 in a plate-shaped member having the same shape and size as the frame portion 3 of the sensor chip 1. The depth of the concave portion 81 or 91 is set to a depth that does not hinder the vibration of the vibrating body 2 and suppresses the displacement of the support portion 4 when an excessive mechanical stress is applied to the vibrating body 2.

FIG. 3B is a plan view showing the inside of another example of the upper lid 8 and the lower lid 9. In this example as well, the upper lid 8 and the lower lid 9 have the same shape. In the case of this example, the concave portion 81 or 9
An area other than the area corresponding to the support portion 4 in 1 is used as the punching through portion 83 or 93. That is, although there is a concave portion that suppresses the displacement of the support portion 4 in the area corresponding to the vibration node of the vibrating body 2 that is the area where the support portion 4 is located, the area corresponding to the antinode of the vibration of the vibrating body 2 is The punching through portion 83 or 93 suppresses the vibration of the vibrating body 2 as much as possible.

FIG. 3C is a view showing a cross section of the sensor chip 1 to which the upper lid 8 and the lower lid 9 are joined.

[0018]

As described above, the present invention comprises a vibrating body formed by anisotropic etching of a semiconductor substrate, a frame portion, and a supporting portion connecting the vibrating body and the frame portion. Of the vibrating body by making the thickness of the supporting part of the same in the direction orthogonal to the length direction of the vibrating body and the middle part of the vibrating body excluding the coupling part 41 to the frame part to be extremely thin in the vertical direction. It is possible to increase the vibration amplitude in the Z-axis direction and the vibration amplitude in the Y-axis direction in which the Coriolis force is generated. Therefore, the change in the output voltage becomes large, the sensitivity of the vibration gyro becomes large, and the applied angular velocity can be accurately detected.

Further, without disturbing the vibration of the vibrating body 2,
In addition, by adopting a configuration in which the upper and lower lids having the recesses set to a depth that suppresses the displacement of the support portion 4 when excessive mechanical stress is applied to the vibrating body 2 are joined to the sensor chip, There is no longer any fear that the body will vibrate greatly and the supporting part will be greatly deformed and damaged.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram illustrating a lid of the embodiment.

FIG. 4 is a perspective view of the embodiment.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor chip 2 Vibrating body 3 Frame part 4 Support part 8 Upper lid 81 Recessed part 82 Frame part 9 Lower lid 91 Recessed part 92 Frame part

Claims (3)

[Claims] 1. A vibrating gyroscope comprising a sensor chip including a vibrating body, a frame portion, and a supporting portion connecting the vibrating body and the frame portion by processing a semiconductor substrate by anisotropic etching. A vibrating gyroscope characterized in that the thickness in the direction orthogonal to the vertical direction is made equal, and the thickness in the vertical direction of the intermediate part excluding the connecting part to the vibrating body and the frame part is extremely thin. 2. The vibrating gyroscope according to claim 1, wherein the frame portion is formed by forming a concave portion in a plate-shaped member having the same shape and size as the frame portion of the sensor chip, and the depth of the concave portion is equal to that of the vibrating body. Vibration that is characterized by joining an upper lid and a lower lid of the same type to the frame, which is set to a depth that does not hinder vibration and that suppresses displacement of the support when excessive mechanical stress is applied to the vibrating body. gyro. 3. The vibrating gyroscope according to claim 2, wherein a region for supporting the displacement of the vibrating body, which is a region where the supporting unit is located, has a recess for suppressing displacement of the supporting unit. The vibration gyro is characterized in that the region corresponding to the antinode of the vibration of the body is a punch-through portion to suppress the vibration of the vibration body as much as possible.