JP2006030062A - Tuning fork piezoelectric oscillating gyroscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized tuning fork oscillating gyroscope superior in processing precision, mass productivity, and having less irregularity of characteristics. <P>SOLUTION: The tuning fork piezoelectric oscillating gyroscope is composed of: a tuning fork piezoelectric oscillator 15 comprising an SOI substrate providing an embedded oxide film layer 5 on a silicon support layer 6 and a silicon activated layer 13 in order, and a piezoelectric monocrystal 14 joined on the silicon activated layer 13, having two leg parts 2 and 3 formed by removing a part of the piezoelectric monocrystal 14, the silicon activated layer 13 and the embedded oxide film layer 5, supported on the silicon support layer 6 through the embedded oxide film layer 5 and comprising the piezoelectric monocrystal 14 and the silicon activated layer 13; drive electrodes 8 and 10, detection electrodes 7 and 11 and a reference potential electrode 9 formed on the piezoelectric monocrystal 14; and a signal processing circuit 12 formed on a part not joining the piezoelectric monocrystal 14 on the silicon activated layer 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gyro device mainly incorporated in a micro navigation system, an attitude control device, a camera-integrated VTR camera shake prevention device, etc. that can be mounted on a portable device, and more particularly to a tuning fork type piezoelectric vibration gyro device using Coriolis force. It is.

  Conventionally, a vibration gyro apparatus using a tuning fork vibrator is known. The principle of this type of vibrating gyroscope is as follows. When the vibrator is applied with vibration (drive mode) at a certain speed, if an angular velocity is detected, the Coriolis force is applied in the direction in which the applied speed and angular velocity of the drive mode are both orthogonal. The generated vibration (detection mode) is excited. Since the excitation speed in the detection mode is proportional to the application speed and the angular velocity in the drive mode, the angular velocity given to the transducer is determined by the magnitude of the excitation speed in the detection mode when the magnitude of the drive mode application speed is constant. Can be calculated. At this time, the piezoelectric vibration gyro apparatus uses a piezoelectric body as means for driving the vibrator and means for detecting the excitation speed in the detection mode proportional to the angular velocity.

  As a conventional piezoelectric vibration gyro device, there are a case where 1) a piezoelectric thin film is used and a case where 2) a piezoelectric single crystal or a piezoelectric ceramic is used.

For example, Patent Document 1 discloses a tuning fork type piezoelectric vibration gyro device using a piezoelectric thin film. FIG. 4 shows a tuning fork type piezoelectric vibrator used in a tuning fork type piezoelectric vibration gyro device using a piezoelectric thin film described in Patent Document 1. As shown in FIG. 4, the tuning fork type piezoelectric vibrator 41 disclosed in Patent Document 1 includes first and second leg portions 42 and 43 that are made of silicon (110) having a thickness of about 0.2 mm. On the main surface 45, a piezoelectric thin film 54 is formed between a Ti / Pt layer having a thickness of approximately 4000 mm as the lower electrodes 50, 51, 52 and 53 and a Ti / Au layer having a thickness of approximately 3000 mm which is the upper electrodes 58, 59, 60 and 61. 55, 56, and 57, a lead zirconate titanate (PZT) thin film having a thickness of approximately 2 to 3 μm is formed by a sputtering method. When a driving voltage is applied between the predetermined electrodes, a driving mode application speed is given to the vibrator by the piezoelectric effect of the PZT thin film. Under this state, when an angular velocity as a detection target is applied, a Coriolis force is generated in a direction perpendicular to the drive mode, and vibration in the detection mode is excited. The vibration in the detection mode is detected from the output voltage generated in the PZT thin film. As the piezoelectric thin film, besides PZT, zinc oxide (ZnO), lithium niobate (LiNbO ₃ ), or the like is also applied.

  As a method for forming the piezoelectric thin film, there are a vacuum vapor deposition method, a chemical vapor deposition (CVD) method, a sol-gel method and the like in addition to the above-described sputtering method. However, in general, a piezoelectric thin film formed by such a method is likely to cause a composition shift due to deficiency of oxygen or the like, and it is not easy to obtain a crystal orientation thin film, and is 500 ° C. in a reactive gas atmosphere such as oxygen. The above high temperature heating or heat treatment is required.

  On the other hand, Patent Document 2 discloses a laser ablation method as another example of a method for forming a piezoelectric thin film. This is a method of forming a thin film by introducing atmospheric gas into a reaction chamber at a constant pressure, irradiating a desired target material with laser light, and depositing a desorbed / injected substance from the target material on a counter substrate. As a feature of this film forming method, it is possible to easily obtain a crystal orientation thin film having the same composition as the target material without introducing a reactive gas such as oxygen or heating the substrate at a high temperature. However, it is possible to achieve consistency with a semiconductor process.

  On the other hand, Patent Document 3 describes a tuning fork type piezoelectric vibrator using a piezoelectric single crystal as another example of a tuning fork type piezoelectric vibrator. FIG. 5 shows a tuning fork type piezoelectric vibrator using the piezoelectric single crystal described in Patent Document 3. As shown in FIG. 5, the tuning fork type piezoelectric vibrator 70 is made of a single piezoelectric material, and in particular, a rotating Y plate of lithium tantalate, lithium niobate, or langasite. Rotating Y plate is a single crystal of lithium tantalate, etc. In an orthogonal coordinate system in which the electrical axis is the X axis, the mechanical axis is the Y axis, and the optical axis is the Z axis, the XZ plane is formed around the Y axis as the main surface It is a thing. The drive electrode 72 including the first drive electrodes 72a and 72c and the second drive electrodes 72b and 72d is formed of, for example, a Cr / Ni thin film, a Ti / Au thin film, or an Al thin film by a sputtering method, a vacuum deposition method, or the like. ing. In general, a vibrator is processed by using a dicing saw, a wet etching method, or a dry etching method in order to cut a desired vibrator shape after forming an electrode. Further, for bonding the vibrator and the support, a flexible adhesive is mainly used in the case of ceramics, and direct bonding or the like is used in the case of a single crystal material. The basic operation of the piezoelectric vibration gyro device is the same as that of the tuning fork type piezoelectric vibration gyro device described in Patent Document 1, and uses a desired piezoelectric single crystal instead of the PZT thin film. Also, in the case of using piezoelectric ceramics, the same effect as that of a piezoelectric vibration gyro apparatus using a piezoelectric single crystal can be obtained.

JP 2003-227719 A JP 2002-324926 A JP 2001-185987 A

Like the tuning fork type piezoelectric vibration gyro device described in Patent Document 1, the piezoelectric thin film has a function of driving a vibrator and a means of detecting an excitation speed in a detection mode proportional to the angular velocity. Typical examples include lead zirconate titanate (PZT), zinc oxide (ZnO), and lithium niobate (LiNbO ₃ ). These piezoelectric thin films are generally formed by a sputtering method, a vacuum deposition method, a sol-gel method, or the like.

  However, as described above, it is necessary to heat the substrate at a high temperature during the film formation, and the reaction between the film formation material and the substrate material or between the film formation material and the lower electrode on the substrate surface becomes a problem. Furthermore, it is very difficult to introduce a reaction gas such as oxygen in the semiconductor process. In general, the film forming speed is about 1 μm / hour at the maximum in the case of sputtering, and about 10 spin coats in order to obtain a film thickness of about 1 to 2 μm in the case of the sol-gel method, Each layer requires a baking process, and it takes several tens of hours or more, so the production efficiency is very poor.

  As described above, formation of a piezoelectric thin film requires a low deposition rate and complicated procedures such as orientation treatment, crystal orientation treatment, and polarization treatment. A laser ablation method has also been proposed.

  According to the laser ablation method, there is little composition shift due to defects such as oxygen, a crystal orientation thin film can be easily obtained, and high temperature heating or heat treatment at 500 ° C. or higher in a reactive gas atmosphere such as oxygen is not required. However, as described in Patent Document 2, it is effective to perform substrate heating (500 ° C. or lower) in an oxygen atmosphere or a nitrogen atmosphere in order to improve crystallinity. In addition, it has been pointed out that the thin film immediately after formation has problems such as poor crystallinity and the presence of defects, and it is currently inferior to single crystal materials in terms of temperature characteristics, heat resistance, etc. .

  When a piezoelectric single crystal or piezoelectric ceramic is used, the piezoelectric material generally includes lithium tantalate, lithium niobate, or langasite. In the processing of the vibrator using these materials, a dicing saw, a wet etching method, or a dry etching method is used in order to cut into a desired vibrator shape after forming an electrode. Further, for bonding the vibrator and the support, a flexible adhesive is mainly used in the case of ceramics, and direct bonding or the like is used in the case of a single crystal material.

  Specifically, the minimum cutting dimension of the piezoelectric vibrator by the dicing saw is generally about 30 μm to 300 μm, and the cutting accuracy is about ± 0.3 μm to ± 5 μm. Actually, due to chipping at the time of cutting processing, the processing accuracy is further deteriorated, which is a big problem in manufacturing the vibrator. For example, in the case of a piezoelectric single crystal such as lithium niobate, chipping of about 10 μm exists on the outer periphery of the cut surface, and in the case of a ceramic material such as PZT, the degree of chipping is more remarkable.

  In contrast, when wet etching or dry etching, which is considered to have good processing accuracy, is applied, it takes a long time to penetrate a piezoelectric single crystal plate having a low etching rate of about 200 to 400 μm and is not suitable for mass production. It is an issue to be.

For example, in addition to wet etching using a mixed solution of hydrofluoric acid (HF) and nitric acid (HNO ₃ ), dry etching such as ion milling and reactive ion etching is used. In wet etching using a HF-based mixed solution, etching is performed. The rate is about 1250 Å / min. In the case of dry etching, ion milling is 400 Å / min, and reactive ion etching (RIE) is 600 Å / min (up to about 2000 Å / min). Therefore, when processing a piezoelectric single crystal such as lithium niobate itself as a vibrator, deep processing of about 200 to 400 μm is required, which requires 30 hours or more.

  However, piezoelectric vibrators using piezoelectric single crystals are mounted on portable devices because they do not require high-temperature heat treatment in a reactive gas atmosphere, which is required when using piezoelectric thin films, and are highly productive. It is often used for a gyro device incorporated in a possible miniature navigation system, attitude control device, camera shake prevention device of a camera-integrated VTR, and the like. However, the piezoelectric single crystal has low processing accuracy and is not suitable for downsizing by the above-described dicing saw cutting, and the etching rate is low for wet etching and dry etching with high processing accuracy, and is not suitable for mass production. Has become an issue.

  Accordingly, an object of the present invention is to solve the above-described problems, to provide a small tuning fork type piezoelectric vibration gyro device which has high processing accuracy, is excellent in mass productivity and has little variation in characteristics.

  According to the present invention, as means for solving the above-described problem, at least two or more of a silicon active layer of an SOI (Silicon-on-Insulator) substrate and a piezoelectric single crystal bonded on the silicon active layer are provided. A piezoelectric vibrator having a leg portion and a support portion for integrally connecting them, a support made of a buried oxide film layer and a silicon support substrate immediately below the support portion, and a drive electrode formed on the piezoelectric single crystal , A detection electrode and a reference potential electrode, and a signal processing circuit formed on the same SOI substrate, and the signal processing circuit has a function of supplying a driving signal for exciting the piezoelectric vibrator to the piezoelectric vibrator. And a tuning fork type piezoelectric vibration gyro device having a function of processing an output signal corresponding to the detected vibration of the piezoelectric vibrator caused by the Coriolis force generated when the angular velocity is given. Furthermore, in the above tuning fork type piezoelectric vibration gyro device, the tuning fork type can adjust the width and thickness of the piezoelectric single crystal and the silicon active layer so that the frequencies of the driving mode and the detection mode of the piezoelectric vibrator substantially coincide with each other. A piezoelectric vibration gyro device is obtained. Further, in the above-described tuning fork type piezoelectric vibration gyro device, a tuning fork type piezoelectric vibration gyro device in which the piezoelectric vibrator is made of only a piezoelectric single crystal is obtained. The piezoelectric single crystal is preferably one of quartz, lithium niobate, zinc oxide, langasite, lithium tantalate, lithium potassium niobate, and potassium niobate.

  That is, the present invention comprises an SOI substrate in which a buried oxide film layer and a silicon active layer are provided in this order on a silicon support layer, and a piezoelectric single crystal bonded on the silicon active layer, the piezoelectric single crystal and the silicon The piezoelectric single crystal has at least two or more legs formed by removing a part of the active layer and the buried oxide film layer and supported by the silicon support layer via the buried oxide film layer. And the tuning fork type piezoelectric vibrator comprising the silicon active layer, the drive electrode, the detection electrode and the reference potential electrode formed on the piezoelectric single crystal, and the piezoelectric single crystal on the silicon active layer are not joined A signal processing circuit formed in a portion, and the signal processing circuit is provided with a function of supplying a drive signal for exciting the piezoelectric vibrator to the piezoelectric vibrator and an angular velocity. Is a tuning fork type piezoelectric vibrating gyro apparatus characterized by and a function of signal processing an output signal responsive to detecting the vibration of the piezoelectric vibrator caused by the Coriolis force generated.

  The present invention is also a tuning fork-type piezoelectric vibration gyroscope comprising a silicon substrate and a piezoelectric single crystal bonded on the silicon substrate, wherein the piezoelectric single crystal and a part of the silicon substrate are removed. A tuning fork type piezoelectric vibrator having at least two legs supported by the silicon substrate and made of the piezoelectric single crystal, a drive electrode, a detection electrode, and a reference formed on the piezoelectric single crystal. A potential electrode, and a signal processing circuit formed on a portion of the silicon substrate where the piezoelectric single crystal is not bonded. The signal processing circuit outputs a drive signal for exciting the piezoelectric vibrator. It has a function of supplying to a piezoelectric vibrator and a function of signal processing an output signal corresponding to the detected vibration of the piezoelectric vibrator caused by a Coriolis force generated when an angular velocity is given. That is a tuning fork type piezoelectric vibrating gyro device.

  In addition, the present invention is the tuning fork type piezoelectric vibration gyro device according to the above tuning fork type piezoelectric vibration gyro device, characterized in that the resonance frequency of the drive mode and the detection mode of the piezoelectric vibrator substantially coincide.

  Further, the present invention provides the above tuning fork type piezoelectric vibration gyro apparatus, wherein the piezoelectric single crystal is any one of quartz crystal, lithium niobate, zinc oxide, langasite, lithium tantalate, lithium potassium niobate, and potassium niobate. There is a tuning fork type piezoelectric vibration gyro device.

  By adopting the above configuration, according to the present invention, the sensitivity is good enough to be incorporated in an ultra-compact navigation system, attitude control device, camera shake prevention device of a camera-integrated VTR, etc. mainly mounted on a portable device. Thus, a tuning fork type piezoelectric vibration gyro device having a small size, little variation in characteristics, and excellent in mass productivity can be provided.

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

  FIG. 1 is a perspective view of a tuning-fork type piezoelectric vibration gyro device according to the present invention. As shown in FIG. 1, a tuning-fork type piezoelectric vibration gyro device 1 according to the present invention includes a first leg 2 and a second leg 3, and a support 4 that connects the legs 2 and 3 together. A tuning fork-type piezoelectric vibrator 15, a buried oxide film layer 5 immediately below the support 4, a support 16 comprising a silicon support layer 6, and a drive electrode 8 formed on the main surface of the first leg 2. , Detection electrode 7, reference potential electrode 9, drive electrode 10, detection electrode 11, reference potential electrode 9 formed on the main surface of second leg 3, and signal processing circuit formed on the same SOI substrate 12 is comprised. The legs 2 and 3 are formed of a silicon active layer 13 and a piezoelectric single crystal 14 of an SOI substrate.

  In this embodiment, a piezoelectric vibration gyro apparatus using lithium niobate as a piezoelectric single crystal will be described. Lithium niobate is particularly suitable for piezoelectric vibratory gyros because the electromechanical coupling coefficient k (hereinafter referred to as coupling coefficient) has an excellent value of, for example, a coupling coefficient k of about 60% in the case of a 140 ° Y-cut plate. It is.

  Specifically, a lithium niobate crystal X plate is used in which the longitudinal direction of the piezoelectric vibrator is parallel to an axis obtained by rotating the Y axis of the crystal by 50 ° with respect to the X axis. As another example, a lithium tantalate crystal X plate in which the longitudinal direction of the vibrator is parallel to an axis obtained by rotating the crystal Y axis by 40 ° with respect to the X axis can be applied. By using such a cut surface, the piezoelectric lateral effect due to the electric field in the width direction of the vibrator is large, and as described below, the electrode can be configured with only one side surface of the piezoelectric vibrator.

  Next, the operation principle of the tuning fork type piezoelectric vibration gyro device in the present embodiment will be described. As shown in FIG. 1, as described above, the tuning fork type piezoelectric vibrator 15 is connected to the driving electrodes 8, 10 coupled to the tuning fork vibration mode as the drive mode and the out-of-plane vibration mode as the detection mode, the detection electrodes 7, 11, A tuning-fork type piezoelectric vibration gyro device is provided in which the reference potential electrode 9 is arranged and capable of detecting the output signal proportional to the excitation and the angular velocity of the piezoelectric vibrator by the drive signal.

  A drive signal having a frequency close to the resonance frequency of the tuning fork vibration mode of the tuning fork type piezoelectric vibrator 15 is applied to the drive electrode 8, the detection electrode 7, the reference potential electrode 9, and the drive electrode of the second leg 3. 10, the tuning fork vibration mode is excited by being applied to the detection electrode 11 and the reference potential electrode 9. Under this state, when an angular velocity is applied with respect to the longitudinal axis of the tuning fork type piezoelectric vibrator 15, a Coriolis force proportional to the angular velocity acts on the first leg 2 and the second leg 3 to cause out-of-plane vibration. Create a mode. If the output signal generated by this out-of-plane vibration mode is detected from the detection electrode 7 of the first leg 2 and the detection electrode 11 of the second leg 3, an output signal proportional to the angular velocity is obtained, and a tuning fork type piezoelectric device is obtained. It can function as a vibration gyro device. In the embodiment of the present invention, the tuning fork vibration mode is used as the drive mode and the out-of-plane vibration mode is used as the detection mode. It can also be used.

  The signal processing circuit 12 has a function of supplying a drive signal for exciting the tuning fork type piezoelectric vibrator 15 to the legs 2 and 3, and a leg caused by Coriolis force generated when an angular velocity is given. It has a function of processing an output signal corresponding to a few detected vibrations.

  Details of the signal processing circuit in this embodiment will be described below. FIG. 2 is a block diagram showing a configuration of the signal processing circuit 12 of the tuning-fork type piezoelectric vibration gyro apparatus according to the present embodiment. A signal output from the self-excited oscillation circuit 102 is applied to the drive electrode 8 of the first leg 2, and a signal obtained by inverting the phase of the signal output from the self-excited oscillation circuit 102 by the phase shift circuit 100 at the same time is used as the second signal. Is applied to the drive electrode 10 of the leg 3 of the fork to excite the tuning fork vibration mode. The detection electrode 7 on the first leg 2 and the detection electrode 11 on the second leg 3 are connected to a current detection circuit including an operational amplifier 111 and a resistor 113, and an operational amplifier 112 and a resistor 114. Thereby, the potentials of the detection electrodes 7 and 11 are fixed to the reference potential by the virtual ground of the operational amplifier. As a result, the detection electrodes 7 and 11 can create a reference potential for applying a drive voltage simultaneously with the detection of the out-of-plane vibration mode. The outputs of the two current detection circuits are input to the addition circuit 101 and the self-excited oscillation circuit 102. The tuning fork vibration mode components of the two signals input to the adder circuit 101 are in opposite phases, and the out-of-plane vibration mode components are in phase. Therefore, the signal input from the addition circuit 101 to the synchronous detection circuit 103 is only an out-of-plane vibration mode component generated by Coriolis force proportional to the angular velocity, and the DC voltage output from the low-pass filter 104 is a voltage proportional to the angular velocity. Become. Further, the signal output from the self-excited oscillation circuit 102 is fed back to the drive electrodes 8 and 10 and the phase shift circuit 100, and at the same time, used as a reference signal for the synchronous detection circuit 103.

Next, a method for manufacturing the piezoelectric gyro vibrator according to the present embodiment will be specifically described with reference to FIG. First, an SOI substrate 31 in which the thickness of the silicon active layer 37 is about 5 μm, the thickness of the buried oxide film 38 is about 2 μm, and the total thickness of the substrate is about 350 μm is used as a start substrate [FIG. A lithium niobate substrate 33 of about 200 μm is bonded at the wafer level by direct bonding [FIG. 3B], and mechanical polishing and CMP (Chemical Mechanical Polishing) are used together to form a lithium niobate substrate. Polishing is performed to about 10 μm [FIG. 3 (c)]. A silicon nitride film 32 having a thickness of about 2000 mm is deposited on the back surface of the SOI substrate 31 by a known CVD (chemical vapor deposition method). Next, a Cr / Au electrode 34 is deposited by a sputtering method or a vacuum deposition method used in a known semiconductor process, and a desired patterning is performed by a photoresist technique and an etching technique [FIG. 3 (d)]. . Further, the lithium niobate, the silicon active layer of the SOI substrate, and the buried oxide film layer are removed by etching using a photolithography technique and a wet etching technique or a dry etching technique to form a void 35 [FIG. 3 (e)]. Regarding the etching of lithium niobate, a mixture of hydrofluoric acid and nitric acid can be used as an etchant in the case of wet etching, and in the case of dry etching, a reactive ion etching (RIE) apparatus is used for fluorine and argon. The reaction gas of the system can be applied. The silicon active layer and the buried oxide film are etched with CF ₄ gas, SF ₆ gas, or the like from a known RIE or Inductively-Coupled Plasma Reactive Ion Etching (ICP-RIE) apparatus. Here, the desired etching of lithium niobate has already been polished by the process of FIG. 3C and has been thinned to about 10 μm, and therefore can be completed in a few tens of minutes to about 1 hour even by a known etching technique. . Finally, the buried oxide film 36 immediately below the first leg 2 and the second leg 3 in FIG. 1 is removed by 48% HF [FIG. 3 (f)]. As described above, the tuning fork type piezoelectric vibration that is small in size, has little variation in shape and characteristics, and has excellent mass productivity by applying the wafer-level bonding technique of piezoelectric single crystal and SOI substrate and batch transfer technology by photolithography technology. A gyro device can be provided.

  In the present embodiment, the size of the tuning fork type piezoelectric vibration gyro device shown is as follows. The first leg 2 and the second leg 3 of the piezoelectric vibrator have a length of about 150 μm and a width of about 15 μm. The thickness of the silicon active layer of the first leg 2 and the second leg 3 of the piezoelectric vibrator is about 5 μm, and the thickness of the lithium niobate that is a piezoelectric single crystal is about 10 μm. Here, the width of the piezoelectric vibrator and the thickness of the silicon active layer and the piezoelectric single crystal may be made substantially equal so that the resonance frequencies of the tuning fork vibration mode as the driving mode and the out-of-plane vibration mode as the detection mode substantially coincide. It is important in improving detection sensitivity. The resonance frequency of the tuning fork type piezoelectric vibrator 15 in this case is approximately equal to about 660 kHz in both the tuning fork vibration mode and the out-of-plane vibration mode.

  Further, by completely etching away the silicon active layer, it is possible to form a piezoelectric vibrator made of lithium niobate alone. In this case, the tuning fork vibration mode and the out-of-plane vibration mode are approximately equal. It is about 590 kHz. In this case, the width of the piezoelectric vibrator made of lithium niobate alone is about 15 μm and the thickness is about 15 μm. Here, the resonance frequency of the piezoelectric vibrator made of lithium niobate alone is reduced by about 70 kHz as compared with the piezoelectric vibrator made of the bonded structure of the silicon active layer and lithium niobate. This is because the mass effect of the piezoelectric vibrator is substantially based on the specific gravity difference between lithium acid and silicon.

  Regardless of the bonded structure of the silicon active layer and lithium niobate, or the structure of lithium niobate alone, the tuning fork vibration mode and the out-of-plane vibration mode resonance frequency can be adjusted by adjusting the width and thickness of the piezoelectric vibrator. Can be controlled. Furthermore, when the drive electrode and the detection electrode are formed only on one main surface of the piezoelectric vibrator as in the tuning fork type piezoelectric vibration gai device shown in the present embodiment, the electric field contributing to the piezoelectric lateral effect is generated at the interface. Even when the thickness of the piezoelectric single crystal is reduced in order to concentrate in the vicinity, there is no significant deterioration in characteristics as a piezoelectric vibration gyro device compared to the piezoelectric single crystal alone. Therefore, it is not necessary to process a piezoelectric single crystal, which is generally difficult to etch, from the wafer level. As shown in this embodiment, the silicon active layer of an SOI substrate with good workability is made to have a tuning fork vibration mode and an out-of-plane vibration. It can be used as frequency adjustment of the mode. In this embodiment, the bonding structure of the piezoelectric single crystal and the silicon active layer of the SOI substrate is described. However, the same effect can be expected even when a normal silicon substrate is used instead of the SOI substrate. Needless to say.

The perspective view of the tuning fork type piezoelectric vibration gyro apparatus in this invention. The block diagram of the signal processing circuit of the tuning fork type piezoelectric vibration gyro apparatus in this invention. The process drawing of the tuning fork type piezoelectric vibration gyro device in the present invention. The perspective view of the tuning fork type piezoelectric vibrator used for the tuning fork type piezoelectric vibration gyro apparatus using the conventional piezoelectric thin film. Explanatory drawing of the tuning fork type piezoelectric vibrator using the conventional piezoelectric single crystal. FIG. 5A is a plan view. FIG. 5B is a bottom view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tuning fork type piezoelectric vibration gyro apparatus 2 (1st) leg part 3 (2nd) leg part 4 Support part 5 Embedded oxide film layer 6 Silicon support layer 7, 11 Detection electrode 8, 10 Drive electrode 9 Reference potential electrode 12 Signal Processing Circuit 13 Silicon Active Layer 14 Piezoelectric Single Crystal 15 Tuning Fork Type Piezoelectric Vibrator 16 Support 31 SOI Substrate 32 Silicon Nitride Film 33 Lithium Niobate Substrate 34 Cr / Au Electrode 35 Gaps 36 and 38 Embedded Oxide Film 37 Silicon Active Layer 41 tuning fork type piezoelectric vibrator 42, 43 leg 44 support part 45 main surface 50, 51, 52, 53 lower electrode 54, 55, 56, 57 piezoelectric thin film 58, 59, 60, 61 upper electrode 70 tuning fork type piezoelectric vibrator 71 Support part 72 Drive electrode 72a, 72c 1st drive electrode 72b, 72d 2nd drive electrode 73A, 73B Leg part 73a One surface side 73b Other surface side 74 Groove 100 Phase shift circuit 101 Addition circuit 102 Self-excited oscillation circuit 103 Synchronous detection circuit 104 Low-pass filter 111, 112 Operational amplifier 113, 114 Resistance

Claims (4)

  A tuning fork type piezoelectric vibration gyro apparatus comprising an SOI substrate in which a buried oxide film layer and a silicon active layer are sequentially provided on a silicon support layer, and a piezoelectric single crystal bonded on the silicon active layer, wherein the piezoelectric single crystal A part of the silicon active layer and the buried oxide film layer is removed, and has at least two legs supported by the silicon support layer through the buried oxide film layer, A tuning fork type piezoelectric vibrator composed of a piezoelectric single crystal and the silicon active layer, a drive electrode, a detection electrode and a reference potential electrode formed on the piezoelectric single crystal, and the piezoelectric single crystal on the silicon active layer are joined. A signal processing circuit formed in a portion not formed, the signal processing circuit having a function of supplying a driving signal for exciting the piezoelectric vibrator to the piezoelectric vibrator, and an angular velocity Tuning fork type piezoelectric vibrating gyro apparatus characterized by and a function of the signal processing output signals responsive to the detection vibration of the piezoelectric vibrator caused by the Coriolis force generated when a given.   A tuning fork-type piezoelectric vibration gyro apparatus comprising a silicon substrate and a piezoelectric single crystal bonded on the silicon substrate, wherein the piezoelectric single crystal and a part of the silicon substrate are removed and formed on the silicon substrate. A tuning fork-type piezoelectric vibrator having at least two or more legs supported and made of the piezoelectric single crystal, a drive electrode, a detection electrode and a reference potential electrode formed on the piezoelectric single crystal, and the silicon A signal processing circuit formed on a portion of the substrate where the piezoelectric single crystal is not bonded, and the signal processing circuit supplies a driving signal for exciting the piezoelectric vibrator to the piezoelectric vibrator. A tuning fork-type piezoelectric vibration having a function and a signal processing of an output signal corresponding to the detected vibration of the piezoelectric vibrator caused by a Coriolis force generated when an angular velocity is given Gyro apparatus.   3. The tuning fork type piezoelectric vibration gyro device according to claim 1, wherein the frequency of the drive mode and the detection mode of the piezoelectric vibrator is substantially the same.   4. The tuning fork type piezoelectric vibration gyro device according to claim 1, wherein the piezoelectric single crystal is made of quartz, lithium niobate, zinc oxide, langasite, lithium tantalate, lithium potassium niobate, or potassium niobate. A tuning fork-type piezoelectric vibration gyro apparatus characterized by being either.

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