WO1998041818A1

WO1998041818A1 - Gyro sensor and video camera using the same

Info

Publication number: WO1998041818A1
Application number: PCT/JP1997/000913
Authority: WO
Inventors: Teruhisa Akashi; Kazutaka Sato; Fumitaka Muranushi; Yoshiko Nishi; Mitsuo Ohtsu; Kanji Kakuta
Original assignee: Hitachi, Ltd.
Priority date: 1997-03-19
Filing date: 1997-03-19
Publication date: 1998-09-24
Also published as: JP3462880B2

Abstract

In a gyro sensor which includes a vibrator formed on the same substrate on which a support portion is formed so that it is supported by the support portion while one of the ends thereof can freely vibrate, and insulating substrate bonded to the back of the substrate and a piezoelectric device bonded to the lower surface of the insulating substrate for vibrating the vibrator in the direction of its thickness by the piezoelectric device, a groove having opposed slopes is disposed on the vibrator, and strain detection means is disposed on the inner side of the opposed slopes of the groove. In this way, the gyro sensor can be made more compact, has a high detection sensitivity and has small variance of sensitivity. A video camera using this gyro sensor is also provided.

Description

Specification

Gyro sensor and video camera using the same

The present invention relates to a gyro sensor for detecting an angular velocity and a device using the same, and in particular, to a vibratory gyro sensor for detecting a corioliser according to an angular velocity by vibrating a beam-shaped vibrator, and a camera shake prevention using the same. It is suitable for video cameras and camera equipment with functions.

Background art

As a vibration type gyro sensor which is miniaturized and reduced in price by applying a micromachining technology, for example, the one described in Japanese Patent Application Laid-Open No. 6-288774 is known.

This vibrating gyro sensor is configured to detect the amount of deflection of a vibrator disposed in the center by a change in capacitance between the vibrator and two detection electrodes. In the above prior art, the capacitance change between the vibrator and the two electrodes is read as a method of detecting the corridor, so the processing accuracy of the electrode part and the capacitance between the electrodes greatly affect the detection sensitivity. I do. Also, in order to increase the sensitivity of the sensor, it is necessary to make the narrow gap between the electrodes uniform and to process with high reproducibility and high processing accuracy. Furthermore, the capacitance of the electrode must be increased by increasing the area of the electrode so that the rate of change in capacitance does not decrease due to the effect of stray capacitance around the wiring.

In addition, silicon must be etched through to form the electrodes, but even if anisotropic silicon etching is used, a small gap of 5 m or less can be achieved. It is difficult to form them uniformly in a plane with good reproducibility.

-Furthermore, in order to increase the area of the electrode part, the vibrator must have a long and narrow structure, which lowers the resonance frequency of the vibrator and lowers the detection sensitivity. Will do.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a gyro sensor that is miniaturized, has high detection sensitivity, and has small variation in sensitivity, a video camera using the gyro sensor, and a method of manufacturing a gyro sensor. And Disclosure of the invention

According to the present invention, there is provided a vibrator formed on the same substrate as the supporting part such that one end is supported by the supporting part in a vibrating manner, an insulating substrate bonded to a back surface of the substrate, and a piezoelectric member bonded to a lower surface of the insulating substrate. A gyro sensor having an element and a vibrator vibrating in a thickness direction by a piezoelectric element, wherein a groove having a slope provided on the vibrator, and a strain detecting means provided on the slope of the groove.

As a result, the vibrator can easily form the substrate by anisotropic etching or the like, and the amount of deflection of the vibrator can be detected on the slope of the groove provided in the vibrator through the strain detecting means. However, a large output voltage can be obtained by taking the differential output voltage of each distortion detecting means. In addition, the thickness of the gyro sensor can be reduced to reduce the overall size.

Also, the present invention provides a vibrator formed on the same substrate as the supporting portion so that one end is supported by the supporting portion in a vibrating state, an insulating substrate joined to a back surface of the substrate, and a lower surface of the insulating substrate. A gyro sensor that has a piezoelectric element joined to the piezoelectric element, and the vibrator vibrates in the thickness direction with the piezoelectric element, wherein the substrate is a silicon substrate, and a through portion is provided in the substrate by etching. A groove provided in the vibrator having a slope formed by anisotropic etching on the surface of the silicon substrate; and a voltage on the slope of the groove. And a distortion detecting means formed by using a depositing resist.

Further, the present invention relates to a video camera equipped with a gyro sensor for vibrating a vibrator in a thickness direction by a piezoelectric element. A silicon substrate fixed to the lens portion, a vibrator formed by etching the silicon substrate to provide a penetrating portion, and a groove having an opposing slope formed on the vibrator by anisotropic etching. A strain detecting means formed by using an electrodeposition resist inside the opposed slope of the groove, and a thin film electrode provided on the silicon substrate and detecting a voltage generated in the strain detecting means. It is. As a result, the thickness of the gyro sensor can be reduced, so that the entire video camera can be reduced in size, and mounting of the gyro sensor on the video camera, such as wiring, can be facilitated.

Further, the present invention provides a vibrator formed on the same substrate as the supporting portion so as to be supported in a vibrating state, an insulating substrate bonded to the back surface of the substrate, and a piezoelectric device bonded to the lower surface of the insulating substrate. A method of manufacturing a gyro sensor, wherein the vibrator is vibrated in the thickness direction by the piezoelectric element. A step of etching the substrate to provide a penetrating portion to form the vibrator; Forming a groove having a facing slope on the formed vibrator by anisotropic etching, applying an electrodeposition resist inside the facing slope, and using the applied electrodeposition resist to form a groove. Forming the strain detecting means inside the opposed slope.

Thus, the method for manufacturing the gyro sensor can be simplified, and the gyro sensor can be made highly accurate and suitable for mass production.

Brief description of the drawings

FIG. 1 is a perspective view showing a gyro sensor according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance when the gyro sensor of FIG. 1 is separated for each substrate.

FIG. 3 is a cross-sectional view schematically showing an AA ′ cross section of FIG.

FIG. 4 is a cross-sectional view schematically showing a BB ′ cross section of FIG. FIG. 5 is a cross-sectional view for explaining a method for detecting koorioka according to one embodiment of the present invention.

FIG. 6 is a block diagram showing a circuit configuration of one embodiment of the present invention. FIG. 7 is a sectional view of a vibrator showing another embodiment of the present invention.

FIG. 8 is a plan view showing a substrate on which a vibrator according to one embodiment of the present invention is formed.

FIG. 9 is a plan view showing a substrate on which a vibrator according to another embodiment of the present invention is formed.

FIG. 10 is a cross-sectional view showing a manufacturing method according to one embodiment of the present invention.

FIG. 11 is a perspective view of a gyro sensor showing another embodiment of the present invention.

FIG. 12 is a perspective view showing a conventional gyro sensor.

FIG. 13 is a perspective view showing the appearance of a video camera on which the sensor according to one embodiment of the present invention is mounted.

FIG. 14 is a perspective view schematically showing an appearance of a lens unit according to one embodiment of the present invention.

FIG. 15 is a plan view showing a mounting board of a gyro sensor according to one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The vibration type gyro sensor used for a video camera or the like needs to reduce the height of the sensor itself and the area occupied by the sensor. In order to prevent camera shake, two axes of angular velocity must be detected, and two sensors are required.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the appearance of the gyro sensor according to the embodiment, FIG. 2 is a perspective view showing the appearance when the gyro sensor of FIG. 1 is separated for each substrate, and FIG. FIG. 4 is a cross-sectional view schematically showing a cross section taken along line AA ′ of FIG. 1, FIG. 4 is a cross-sectional view schematically showing a cross section taken along line BB ′ of FIG. 1, and FIG. FIG. 6 is a cross-sectional view for explaining a method for detecting a liolika, FIG. 6 is a block diagram showing a circuit configuration of one embodiment, FIG. 7 is a cross-sectional view of a vibrator showing another embodiment, and FIG. FIG. 9 is a plan view showing a substrate on which a vibrator of one embodiment is formed, FIG. 9 is a plan view showing a substrate on which a vibrator of another embodiment is formed, and FIG. 10 is a manufacturing method of one embodiment. Sectional view, FIG. 11 is a perspective view showing another embodiment, FIG. 12 is a perspective view showing a conventional example, and FIG. 13 is a video camera on which two sensors of one embodiment are mounted. FIG. 14 is a perspective view schematically showing the appearance of a lens unit according to one embodiment, and FIG. 15 is a perspective view schematically showing the appearance of a lens unit according to one embodiment. Mounting board It is a plan view.

In FIG. 13, reference numeral 131 denotes a video tape mounting section, which is composed of a power camera section 132, an audio input section 133, and a part of a finder 134. In the figure, the camera part 132 is partially cut, and the lens part 135 and the gyro sensor mounting board 136 are arranged.

In FIG. 14, on a gyro sensor mounting board 1 36, a gyro sensor 14 1 for detecting horizontal shake and a gyro sensor 14 2 for detecting vertical shake are mounted. The mounting substrate 135 is fixed to the lens portion 135 by screwing or the like to be integrated.

When the lens section 135 moves in the horizontal and vertical directions, the mounting board 135 also moves at the same time, and the angular acceleration in each direction is detected by the sensors 141 and 142.

In FIG. 15, it is desirable from the viewpoints of sensitivity, accuracy, and the like, that the sensors 14 1 and 14 2 be arranged as close as possible to the lens optical axis 15 2 at the lens outer diameter position 15 1. However, since the sensors 14 1 and 14 2 are both vibratory gyro sensors, the resonance frequencies of the sensors should not be resonated with each other. It is shifted about 0 0 Hz.

In FIG. 1, the package section and the amplifier circuit section are omitted. The gyro sensor is composed of three types of substrates, a bulk piezoelectric substrate 1 that is a piezoelectric element, an insulating glass substrate 2 that is an insulating substrate, and a silicon substrate 3 that forms a vibrator. I have. The size of the gyro sensor is about 4 x 14 mm and the thickness is about 2 mm.

The plane orientation of the silicon substrate 3 is {100}, and anisotropic etching of the silicon forms nine or more silicon openings to form a penetrating part, forming a cantilever. The vibrator 4 is provided with a groove 5 having a facing slope formed by anisotropic etching.

The anisotropic etching of silicon is performed using an alcohol-based etchant such as an aqueous solution of hydroxylated water (K0H) or tetramethylaminoammonium hydroxide (TMAH).

Also, a piezoelectric thin film 6 made of Zn 0 for detection and a piezoelectric thin film 7 for feedback are formed as strain detecting means on the inner side surface and the bottom surface of the groove 5 facing the slope. In order to detect the voltage generated on these piezoelectric thin films, a GND electrode 10 is laminated as a common electrode with the thin film electrode 8 so as to sandwich both piezoelectric thin films.

On the piezoelectric substrate 1, thin film electrodes 12 for driving a piezoelectric substrate for extending and contracting vibration in the X direction are formed on both sides. When a voltage of a certain frequency is applied to this electrode, the piezoelectric substrate 1 vibrates at that frequency, and the vibrator 4 formed on the silicon substrate 3 is excited in the X direction.

The glass substrate 2 is for preventing the silicon substrate 3 and the electrode 12 of the piezoelectric substrate 1 from being short-circuited, and further has a glass recess 11 formed thereon.

The glass recess 1 1 prevents the vibrator 4 from contacting the glass substrate 2 Is formed. Since the vibrator is formed using silicon anisotropic etching, the cross-sectional shape of the opening 9 is a reverse tapered shape, and the cross-sectional shape of the vibrator 4 is bilaterally symmetrical and reverse-tapered U-shaped. It has become.

The cross-sectional dimensions of the vibrator are approximately a: 350 βm. B: 200 m, c: 900 m, d: 130 m. Piezoelectric is applied to the opposing slope facing the groove 5 of the vibrator 4. A thin film 6 is formed, and a piezoelectric thin film 7 for feedback is provided on the bottom of the groove 5, and the piezoelectric thin films 6, 7 are patterned without being connected to each other.

Next, the method of sensing the angular velocity of the vibrating gyro sensor will be described with reference to Figs. When the vibrator 4 with mass m vibrates at a velocity V in the X direction due to the piezoelectric substrate 1 and an angular velocity ω is applied around the Z axis, a corerica F (= 2 mVω) corresponding to the angular velocity is generated. I do. Since the coriolis is applied in the Υ direction, the vibrator 4 bends in the Υ direction, resulting in a combined vibration in the X and Υ directions.

The amount of deflection can be detected as a voltage change between the piezoelectric thin film 6 and the piezoelectric thin film 7 formed in the groove 5 at Ζη 0.

Fig. 5 is an explanatory diagram of the operation at the time of non-rotation with no angular velocity applied and at the time of rotation with angular velocity applied.When the vibrator 4 is vibrating in the X direction at speed ν and force f, It bends and vibrates in the direction. Therefore, distortion due to f occurs in the two piezoelectric thin films 6 in the same direction as the excitation direction.

The output voltage value generated in the piezoelectric thin film when a decomposition component of the force f is applied in the thickness direction of the piezoelectric thin film 6 is defined as A 1. Next, when angular velocity F is applied in the direction shown in the figure by applying angular velocity about the Z axis (during rotation), the vibrator 4 vibrates in the direction of the resultant force of f and F. The voltage value generated by the core F is assumed to be A 2. Therefore, when a decomposition component of the resultant force is added in the thickness direction of the piezoelectric thin film 6, the output voltage values generated in each of the detecting piezoelectric thin films 6 are A 1 -A 2 and A 1 + A 2, respectively. The absolute value of these differential output voltage values is 2 A 2 is obtained, and the output voltage value twice as high as the voltage generated in each piezoelectric thin film by the corerica F can be obtained.

The output from the piezoelectric thin film 6 obtained by the combined vibration of the force f and the coriolis F is input to the filter built-in differential amplifier circuit 14 as shown in Fig. 6, and the disturbance component of the sensor Press to extract the voltage value of the Coriolis F. At the same time, the piezoelectric substrate 1 is vibrated by the oscillation circuit 13, and the oscillation frequency is monitored by the piezoelectric thin film 7 formed on the oscillator 4, and the oscillation frequency is fed back to the oscillation circuit 13 to adjust the frequency. The signal obtained through the differential amplifier circuit 14 with this frequency as a reference is detected by the synchronous detection circuit 15. Further, the detected voltage value is amplified by the DC amplifier circuit 16 and is extracted as a signal by the corerica. As described above, the angular velocity is detected.

Next, another embodiment of the cross-sectional structure of the vibrator 4 will be described with reference to FIG. If silicon anisotropic etching is used for (a) described in one embodiment, (b), (c) and (d) can be obtained.

In the case of (a), the grooves 5 are formed by performing anisotropic etching from the front side of the silicon substrate 3, and then the openings 9 are formed by performing anisotropic etching from the back side, whereby the U Make a character structure.

In the case of (b), when forming the groove 5 by performing anisotropic etching from the front side, a portion to be penetrated is etched to some extent in advance, and then anisotropic etching is performed from the back surface to penetrate, thereby obtaining vibration. A child 4 can be formed. At this time, the amount of etching from the back surface can be made smaller than in the case of (a).

In (a) and (b), the piezoelectric thin film 7 is not always necessary. However, as described in FIG. 6, the provision of the piezoelectric thin film 7 allows the oscillation circuit 13 to feed back the signal from the piezoelectric thin film 7, so that The frequency can be adjusted, and higher sensitivity and higher sensitivity can be achieved.

Next, in the case (c), the cross-sectional structure of the vibrator 4 is V-shaped, and the piezoelectric thin film 7 is not formed to simplify the structure.

(d) is an extension of the type of (a), where two grooves 5 are formed,

It is possible to increase the detection sensitivity as compared with (a).

8 and 9 show another embodiment of the vibrator 4. FIG. In the case where the cross-sectional shape of the vibrator 4 is (a) in FIG. 7, the shapes of the front and back surfaces of the silicon substrate 3 are shown in FIG. 8 (a) shows the front surface shape of the silicon substrate 3, and FIG. 8 (b) shows the rear surface shape of the silicon substrate 3.

Since the silicon substrate 3 has a plane orientation of {100}, when anisotropic etching is performed, as shown in (b), the face of the {111} silicon crystal plane 17 is reduced as shown in (b). A par slope is formed. Also, the larger the vibrating body mass and the faster the vibrating body speed, the larger Coriolis F is. For this purpose, a weight portion 18 may be formed at the tip of the oscillator 4 as shown in FIG. As a result, the tip of the vibrator 4 becomes heavier, the excitation amplitude becomes larger, and the deflection of the vibrator by the corioliser F increases, so that the voltage generated in the piezoelectric thin film 6 increases and the sensitivity improves.

Next, the manufacturing process of the vibrator 4 on which the piezoelectric thin film 6 and the piezoelectric thin film 7 are formed will be described in order of (a) to (g) with reference to FIG.

(a): A groove 5 is formed on the surface of a silicon substrate 3 having a plane orientation of {100} by anisotropic etching. The anisotropic etching is performed using an alkaline etchant, for example, an aqueous solution of potassium hydroxide (K 0 H) / tetramethylammonium hydroxide (TMAH). Next, thermal oxidation is performed to form a SiO ₂ film 19 on the silicon substrate 3. The front side of the S i 0 ₂ film pattern training to form the S i 0 ₂ pattern 2 0 is found. (b): A lower electrode 21 formed of a two-layer thin film of chromium and gold is formed on the front side of the silicon substrate 3 by vapor deposition or sputtering.

(c): Next, a resist is applied to the substrate using an electro-deposited photosensitive resist coated by electrophoresis. Further, the lower electrode 21 is patterned through a photolithography process to obtain a lower electrode pattern 22.

(d): A piezoelectric thin film 23 of ZnO and an upper electrode 24 are sequentially formed by sputtering so as to cover the lower electrode pattern 22. The upper electrode 24 here is formed of the same chromium and gold two-layer thin film as the lower electrode 21. In addition, a conductive thin film such as an anode thin film can be used.

(e): Using an electrodeposition (photosensitive) resist, apply the resist on the substrate surface. Thereafter, the upper electrode thin film 24 and the ZnO thin film 23 are similarly patterned through a photolithography process to obtain an upper electrode pattern 26 and a Zn0 thin film pattern 25. The Zn 0 thin film pattern 25 and the upper electrode pattern 26 are formed on the slope of the anisotropic etching groove 5.

In the processes (c) and (e), the electrodeposition resist is used. Even when the groove depth is more than 100 // m, the side and bottom of the groove 5 can be covered with the resist. Because.

(f): Patterning the SίO ₂ film 19 on the back surface to form a back Si opening 27.

(g): The front surface of the substrate 3 is covered with a jig so that the etchant does not penetrate, and anisotropic etching by K0H is performed from the back surface to form a penetrating portion. At this time, first, a SiO ₂ thin film is formed on the surface and etching is performed.

Next, as another embodiment, a vibratory gyro sensor capable of detecting angular velocity of two axes with one element will be described with reference to FIG. In this embodiment, two gyroscopes are integrated to detect the angular velocity of two axes. This is advantageous for further miniaturization.

11 has the same basic configuration as that of FIG. 1, except that two vibrating beams are formed on a piezoelectric substrate 1 via an insulating glass substrate 2 so as to cross each other at right angles. One is a vibrator 28 for detecting angular acceleration around the Z-axis, and the other is a vibrator 29 for detecting angular acceleration around the Y-axis. The dimensions and position of each part are determined so that the resonance frequencies of these vibrators are shifted in advance so as not to interfere with each other.

Also, piezoelectric thin films 30 and 32 and Zn0 thin films 31 and 33 for detection are formed respectively, and the angular velocity detection of the Y axis and the Z axis is performed in the same manner as in the case of FIG.

In the above embodiment, the piezoelectric thin film is formed as the strain detecting means on the slope of the groove. However, the strain detecting means is not limited to the piezoelectric thin film.For example, a bulk piezoelectric body is stuck on the slope of the groove. The same effect can be expected even if the material is used.

According to the present invention, it is possible to obtain a gyro sensor that is miniaturized, has high detection sensitivity, and has small variation in sensitivity, and a video camera and a gyro sensor manufacturing method using the gyro sensor. In addition, the following can be specifically stated.

(1) It can be manufactured by micromachining technology, has a simple configuration, and is highly productive.

(2) Since it is composed of a bonding substrate consisting of three layers of a piezoelectric element, an insulating substrate, and a vibrator, the thickness is small, the area occupied by the sensor is small, and miniaturization and integration are possible. There is no need to take up much space even if multiple units are installed on the rack.

(3) Grooves are provided in the vibrator, and the piezoelectric thin film, which is the strain detection means, is provided on the inner surface opposite to the grooves, so that cost can be reduced and variation in shape between elements can be suppressed. Variation in sensor output sensitivity Can be suppressed.

(4) Since the output variation between sensors can be suppressed, if this sensor is mounted on a video camera, etc., a correction circuit and control software for adjusting the sensor sensitivity in the post-process after mounting will be added. Is unnecessary.

Claims

Scope of request

1. A vibrator formed on the same substrate as the supporting portion such that one end is supported by the supporting portion in a freely oscillating state, an insulating substrate bonded to the back surface of the substrate, and a piezoelectric device bonded to the lower surface of the insulating substrate. A gyro sensor that includes an element and vibrates the vibrator in the thickness direction by the condensing element.

A groove having a slope provided in the vibrator,

A gyro sensor, wherein a piezoelectric thin film is provided on a slope of the groove.

2. A vibrator formed on the same substrate as the supporting portion such that one end is supported by the supporting portion in a freely oscillating state, an insulating substrate bonded to the back surface of the substrate, and a piezoelectric device bonded to the lower surface of the insulating substrate. A gyro sensor having the element and vibrating the vibrator in the thickness direction with the piezoelectric element.

The vibrator formed by providing a through-hole in the substrate by etching, wherein the substrate is a silicon substrate;

A groove provided in the vibrator having a slope formed by anisotropic etching on a surface of the silicon substrate;

A gyro sensor comprising: strain detecting means formed on the slope of the groove using an electrodeposition resist.

3. In a video camera equipped with a gyro sensor that vibrates the vibrator in the thickness direction with a piezoelectric element,

A substrate fixed to a lens portion of the video camera;

The vibrator formed by etching the substrate to provide a through portion;

A groove having an opposing slope formed on the vibrator by anisotropic etching, and a strain detecting means formed using an electrodeposition resist inside the opposing slope of the groove;

A thin-film electrode provided on the substrate for detecting a voltage generated in the strain detecting means; When

A video camera comprising:

4. A vibrator formed on the same substrate as the supporting portion so as to be supported in a vibrable state, an insulating substrate bonded to the back surface of the substrate, and a piezoelectric element bonded to the lower surface of the insulating substrate. A method for manufacturing a gyro sensor, in which the vibrator is vibrated in the thickness direction by the piezoelectric element,

Forming the vibrator by providing a penetrating portion by etching the substrate; and forming a groove having a facing slope by anisotropic etching in the formed vibrator;

Applying an electrodeposition resist to the inside of the opposed slope,

Forming strain detecting means inside the opposite slope using the applied electrodeposition resist;

A method for manufacturing a jay mouth sensor, comprising: