JP5034541B2 - Piezoelectric vibrator, oscillator - Google Patents

Description

The present invention relates to a piezoelectric vibrator having a piezoelectric thin film element made of a piezoelectric thin film and a method for manufacturing the piezoelectric vibrator.

In general, a low-frequency piezoelectric vibrator is used as a time standard or sensor mounted on an electronic device or the like. In response to the downsizing of electronic equipment, downsizing of these piezoelectric vibrators is required.
When the piezoelectric vibrator is simply reduced in size, the CI value increases and the Q value decreases. As a structure that does not increase the CI value, there is a method in which a piezoelectric film is formed on a vibrating piece and this piezoelectric film is driven.
Specifically, the first, the inner side and the outer side of the center line on the main surface of the vibrating arm of a tuning fork made of silicon,
A second electrode, first and second piezoelectric films respectively provided on the electrodes, and third and fourth electrodes provided on the piezoelectric films, respectively, There has been proposed a thin film micromechanical resonator in which a tuning fork bends and vibrates by applying AC voltages having opposite phases to a fourth electrode (see, for example, Patent Document 1).

JP 2003-227719 A (Page 9, FIGS. 1 and 2)

In Patent Document 1 described above, a tuning fork is excited by applying a voltage to an electrode in a form in which a piezoelectric film is sandwiched between electrodes. In such a structure, in order to obtain the driving force for driving the tuning fork, the thickness of the piezoelectric film must be about several μm, the capacitor capacity becomes large, and the clock signal application that constantly generates a signal is consumed. There is a problem that electric power becomes large.

The vibration performance of a vibrator or resonator using a piezoelectric film is better as the crystallinity of the piezoelectric film is better, and better crystallinity is obtained as the film formation temperature is higher. However, the method of simply forming the piezoelectric film on the silicon surface does not provide uniform and good crystallinity of the piezoelectric film,
In the case of a high temperature, there is a problem that materials such as tuning forks and electrodes are restricted.

An object of the present invention is to provide a high-accuracy piezoelectric vibrator that is small in size, consumes less power and has a small amount of frequency temperature change, and a method of manufacturing a piezoelectric vibrator having a piezoelectric thin film having good crystallinity.

The piezoelectric vibrator of the present invention has a base, at least a pair of vibrating arms extending in parallel from the base, and excitation electrodes having different polarities on the main surface or side surfaces of each of the pair of vibrating arms. A piezoelectric thin film element comprising: a piezoelectric vibrating piece; a piezoelectric thin film provided on at least one surface of the opposing main surface or side surface of each of the pair of vibrating arms; and an electrode formed on the surface of the piezoelectric thin film; The piezoelectric vibrating piece and the piezoelectric thin film element are connected in series. Further, in one embodiment, a base includes a vibrating arm extending from the base, and the vibrating arm includes a first surface, a second surface facing the first surface, and the first surface. A first electrode is formed on the first surface and the second surface in the extending direction of the vibrating arm, and the side surface connecting the end portion and the end portion of the second surface. A second electrode is formed on a side surface in the extending direction of the vibrating arm, and is formed on at least one of the first surface and the second surface on the piezoelectric layer and the piezoelectric layer. A stacked portion including the third electrode, the stacked portion is disposed in parallel with the first electrode, the first electrode and the second electrode have different polarities, and the first electrode and the third electrode The electrode is characterized by the same polarity. The resonating arm includes a first resonating arm and a second resonating arm, the first resonating arm and the second resonating arm extending in parallel from the base, and having the same electrode arrangement, The first electrode of the first vibrating arm is connected to the first electrode of the first vibrating arm, the third electrode of the first vibrating arm, and the second electrode of the second vibrating arm. And the first electrode of the second vibrating arm and the third electrode of the second vibrating arm are connected to each other. Moreover, it is good also as an oscillator provided with the said piezoelectric vibrator and the amplifier circuit connected to the said piezoelectric vibrator.

According to the present invention, the piezoelectric vibrating piece and the piezoelectric thin film element made of the piezoelectric thin film are connected in series, and the piezoelectric vibrating piece and the piezoelectric thin film element are excited by the same excitation signal. The piezoelectric thin film element can be miniaturized in the low frequency region by mutually supplementing the body thin film element with vibration. If the piezoelectric vibrator is used, a small-sized and low power consumption oscillator can be configured.

In addition, since the piezoelectric vibrating piece and the piezoelectric thin film element are connected in series, the total capacitor capacity of the piezoelectric vibrating piece and the piezoelectric thin film element can be reduced, and this does not increase power consumption. In addition, the piezoelectric vibrator can be reduced in size.

Moreover, it is preferable that the capacitor capacity of the piezoelectric thin film is larger than the capacitor capacity of the piezoelectric vibrating piece.

In the present invention, the piezoelectric vibrating piece and the piezoelectric thin film element are connected in series. Here, when the capacitor capacity of the piezoelectric vibration side is represented by Cq and the capacitor capacity of the piezoelectric thin film is represented by Cz, the capacitor capacity C of the piezoelectric vibrator is represented by 1 / C = 1 / Cq + 1 / Cz. Here, if Cz> Cq and the difference is sufficiently large, it can be considered that C≈Cq. Therefore, the piezoelectric vibrator capacitor capacitance C can be reduced, and the quartz vibrator can be downsized without increasing the power consumption.

  The piezoelectric vibrating piece is preferably made of quartz.

Since the piezoelectric vibrating piece made of quartz is excellent in frequency temperature characteristics, the excellent frequency temperature characteristics inherent in quartz can be utilized even in a structure using a piezoelectric thin film complementarily.

Further, the pair of vibrating arms extends along the Y-axis direction of the crystal, one of the opposed main surfaces is divided into two in the X-axis direction of the crystal, and the piezoelectric thin film element is divided into two The main surface is preferably provided on the crystal axis direction side of the crystal.

As described above, by connecting the piezoelectric vibrating piece and the piezoelectric thin film element in series and disposing the piezoelectric thin film element on the crystal axis direction side of the crystal, the vibration mode of the piezoelectric vibrating piece and the piezoelectric thin film element can be changed. Accordingly, the piezoelectric vibrating piece and the piezoelectric thin film element can complement each other for vibration.

In addition, the pair of vibrating arms extends along the Y-axis direction of the crystal, both of the opposing main surfaces are divided into two in the X-axis direction of the crystal, and the piezoelectric thin film element is divided into two. It is preferable that the opposing main surfaces are provided on the crystal axis direction side of the crystal.

By providing the piezoelectric thin film elements on both the front and back surfaces of the piezoelectric vibrating piece, the piezoelectric vibrating piece and the piezoelectric thin film element can complement each other more strongly with each other. In addition, vibration balance can be achieved as compared with a structure in which a piezoelectric thin film element is provided on one main surface (either one of the front and back surfaces).

In addition, the pair of vibrating arms extends along the Y-axis direction of the crystal, both of the opposing main surfaces are divided into two in the X-axis direction of the crystal, and the piezoelectric thin film element is divided into two. It is preferable that the opposing main surfaces are provided on the crystal axis direction side of the crystal in the crystal axis direction of the crystal and on the side surface opposite to the crystal axis direction of the crystal.

In this way, by providing the piezoelectric thin film element also in the thickness direction (Z-axis direction) of the crystal, it is possible to more strongly complement each other and to increase the vibration efficiency of the piezoelectric vibrator. it can.

  Further, it is preferable that a balance mass is added to the vibrating arm.

By providing the piezoelectric thin film element on the surface of the vibrating arm, it is expected that the balance of vibration is slightly broken. Therefore, by adding a balance mass corresponding to the piezoelectric thin film element, it is possible to balance the vibration of the vibrating arm and maintain highly accurate vibration characteristics.

  The balance mass is preferably formed of the same material as the piezoelectric thin film.

In this way, since the balance mass can be formed in the same process as the piezoelectric thin film, a highly accurate balance mass can be added. Moreover, it is possible to use a piezoelectric thin film forming facility.

The method for manufacturing a piezoelectric vibrator of the present invention includes a step of forming a first piezoelectric thin film on a surface of a piezoelectric substrate, a step of heat-treating the first piezoelectric thin film, and the heat-treated first piezoelectric thin film. Forming a piezoelectric thin film by laminating a second piezoelectric thin film of the same material as the first piezoelectric thin film on the surface of the first piezoelectric thin film.

The vibration performance of a vibrator or resonator using a piezoelectric thin film is better as the crystallinity of the piezoelectric thin film is better. Therefore, the first piezoelectric thin film is heat-treated, and the first piezoelectric thin film is formed on the surface of the first piezoelectric thin film.
By forming the second piezoelectric thin film of the same material as the piezoelectric thin film, good crystallinity is obtained,
Excellent vibration performance can be obtained.

The method for manufacturing a piezoelectric vibrator of the present invention includes a step of forming at least one metal thin film of Pt or Ti on the surface of the piezoelectric substrate, and a step of forming a piezoelectric thin film on the surface of the metal thin film. It is characterized by that.

By forming a metal film of Pt or Ti on the surface of the piezoelectric substrate, the crystallinity of the piezoelectric thin film can be improved. Here, the metal film may be a single layer of Pt or Ti, and Ti and P
It is good also as a laminated structure of t. Note that the metal film is electrically floating.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 5 show a piezoelectric vibrator and manufacturing method according to Embodiment 1 of the present invention, FIGS. 7 and 8 show Embodiment 2, FIGS. 9 and 10 show Embodiment 3, and FIG. 11 shows Embodiment 4. FIG. ing. Note that the drawings referred to in the following description are schematic views in which the vertical and horizontal scales of members or portions are different from actual ones for convenience of illustration.
(Embodiment 1)

FIG. 1 is a perspective view showing the structure of a piezoelectric vibrator according to Embodiment 1 of the present invention, and FIG.
It is sectional drawing which shows -A cut surface, and connection explanatory drawing of each electrode. The material of the piezoelectric vibrator of the present invention can be applied as long as it has piezoelectric performance, but in the following embodiments, a quartz crystal vibrator will be described as an example of the piezoelectric vibrator. 1 and 2, the crystal resonator 10 includes a plurality of electrodes and piezoelectric thin film elements 100 and 101 on the surface of a crystal resonator element 20.

The quartz crystal vibrating piece 20 has a pair of vibrating arms 3 extending from one side of the base portion 21 in parallel to the Y-axis direction.
It is a tuning fork type vibrator having 0 and 40. A support portion 22 is provided in a direction opposite to the extending direction of the vibrating arms 30 and 40 of the base portion 21. Vibrating arms 30 and 40 are symmetrical with respect to the center line C _0. Further, the crystal vibrating piece 20 is cut out with the crystal axis direction as the X-axis direction.

The vibrating arm 30 is divided into one main surface (first surface) 31 (hereinafter referred to as the surface 31) in two, and the crystal axis direction (inner direction of the vibrating arm, or the center line C1 of the vibrating arm 30) A piezoelectric thin film (piezoelectric layer) 71 is formed in the first region, and an electrode (first electrode) 51 is formed in the outer direction (or the second region) , and a main surface (second surface) 32 (facing the surface 31 ) Hereinafter, an electrode (first electrode) 53 is formed on the rear surface 32). The electrode 53 may be divided into two so as to face the piezoelectric thin film 71 and the electrode 51, and may be omitted. Further, an electrode (second electrode) 52 is formed on the outer side surface 33 of the vibrating arm 30, and an electrode (second electrode) 54 is formed on the inner side surface 34. Furthermore, an electrode (third electrode) 55 is formed on the surface of the piezoelectric thin film 71.

In the vibrating arm 40, one main surface (first surface) 41 (hereinafter referred to as the surface 41) is divided into two, and the crystal axis direction (the outer direction of the vibrating arm, or the center line C2 of the vibrating arm 40, or A piezoelectric thin film (piezoelectric layer) 72 is formed in the second region), and an electrode (first electrode) 56 is formed in the inner direction (or the first region) . The other main surface (second surface) 42 (hereinafter referred to as the back surface) Electrode (first electrode) 58 is formed. The electrode 58 may be divided into two so as to face the piezoelectric thin film 71 and the electrode 56, or may be omitted. Further, an electrode (second electrode) 59 is formed on the outer side surface 43 of the vibrating arm 40, and an electrode (second electrode) 57 is formed on the inner side surface 44. Furthermore, an electrode (third electrode) 60 is formed on the surface of the piezoelectric thin film 72.

As the material of the piezoelectric thin films 71 and 72, ZnO, AlN, GaN, PZT (registered trademark)
, KN, LN, LT, and the like. In this embodiment, a material having a larger dielectric constant than quartz, a material having a large difference, a material having a large Young's modulus, and a material having a large electromechanical coupling coefficient K ² are used. select.

The electrodes 55, 51, 53, 57, 59 and the connection terminal 93 are connected by a connection electrode 91. In addition, the electrodes 52, 54, 58, 60, 56 and the connection terminals 94, which are different from those of the electrodes, are connected by a connection electrode 92. Then, by applying alternating voltages having opposite phases to the connection terminals 93 and 94, the vibrating arms 30 and 40 bend and vibrate in the X-axis direction. Accordingly, the electrodes 51 to 60 are excitation electrodes of the crystal vibrating piece 20.

FIG. 3 is an equivalent circuit diagram showing a state in which the crystal resonator is connected to an oscillation circuit that excites in a specific vibration mode. In FIG. 3, the oscillation circuit 80 includes an amplifier circuit 81 and a feedback circuit 82.

The amplifier circuit 81 includes an amplifier 83 and a feedback resistor 84. Feedback circuit 82
Includes a drain resistor 85, capacitors 86 and 87, and a crystal resonator 10. In the crystal resonator 10, a crystal resonator element 20 and piezoelectric thin film elements 100 and 101 are connected in series (see also FIG. 2).

Here, the amplifier 83 can use a CMOS inverter. With such a configuration, it is possible to form an oscillator 80 in which the quartz crystal vibrating piece 20 and the piezoelectric thin film elements 100 and 101 vibrate in the same vibration mode.

Next, driving of the crystal resonator according to the present embodiment will be described with reference to the drawings.
4 and 5 are explanatory diagrams schematically showing driving of the crystal resonator. 4 and 5 show the AA cut plane of FIG.
The first state will be described with reference to FIG. A negative (−) potential is applied to the electrodes 51, 53, 55, 57 and 59, and a positive (+) potential is applied to the electrodes 52, 54, 56, 58 and 60. Here, the crystal axis direction of the crystal of the vibrating arms 30 and 40 is represented by an arrow D, and the polarization direction of the piezoelectric thin films 71 and 72 is represented by an arrow P ₀ .

First, the vibrating arm 30 will be described. The piezoelectric thin film 71 is in a state in which the piezoelectric thin film element 100 sandwiched between the electrode 55 and the electrode 54 is formed (a part of the crystal is interposed), and the electrode 55 has a negative potential. When a positive potential is applied to the electrode 54, the electrode 54 shrinks in the thickness (Z-axis) direction, and the width (
X-axis) direction and length (Y-axis) direction.

Therefore, the piezoelectric thin film 71 is provided at a position offset in the crystal axis direction of the quartz crystal.
An attempt is made to displace the vibrating arm 30 in the direction of arrow F ₁ . When a voltage is applied to each of the electrodes, the vibrating arm 30 generates an electric field in the direction of arrow E and tends to be displaced in the direction of arrow F _{1. The} vibrating arm 30 is displaced in the direction of arrow F ₁ together with the piezoelectric thin film element 100. To do.

Next, the vibrating arm 40 will be described. The piezoelectric thin film 72 is a state in which the piezoelectric thin film element 101 sandwiched between the electrode 60 and the electrode 59 is formed (partially interposing a crystal), and the electrode 6
When a positive potential is applied to 0 and a negative potential is applied to the electrode 59, it extends in the thickness (Z-axis) direction and the width (X
(Axis) direction and length (Y axis) direction.

Therefore, since the piezoelectric thin film 72 is provided at a position offset in the crystal axis direction of the crystal,
Attempts to displace the vibrating arm 40 in the arrow F ₂ direction. When a voltage is applied to each of the electrodes, the vibrating arm 40 generates an electric field in the direction of arrow E and tends to move in the direction of arrow F ₂ , so the vibrating arm 40 is displaced in the direction of arrow F ₂ together with the piezoelectric thin film element 101. To do.
In this way, the vibrating arms 30 and 40 are both displaced outward as shown in FIG.

Next, the second state will be described with reference to FIG. The 2nd state has shown the state which applied the voltage of the reverse phase to each electrode with respect to the 1st state mentioned above. That is, the electrodes 51 and 53
, 55, 57, 59 are applied with a positive (+) potential, and the electrodes 52, 54, 56, 58, 60 are applied.
A negative (-) potential is applied to.

First, the vibrating arm 30 will be described. When a negative potential is applied to the electrode 55 and a positive potential is applied to the electrode 54, the piezoelectric thin film 71 extends in the thickness (Z-axis) direction, and the width (X-axis) direction and length (Y
Shrink in the (axis) direction.

Accordingly, the piezoelectric thin film 71 tends to displace the vibrating arm 30 in the direction of the arrow F ₃ . Vibration arm 3
In the case of 0, when a voltage is applied to each electrode, an electric field is generated in the direction of arrow E, and also tends to be displaced in the direction of arrow F ₃ , so that the vibrating arm 30 is displaced in the direction of arrow F ₃ together with the piezoelectric thin film element 100.

Next, the vibrating arm 40 will be described. When a negative potential is applied to the electrode 60 and a positive potential is applied to the electrode 59, the piezoelectric thin film 72 contracts in the thickness (Z-axis) direction, and the width (X-axis) direction and length (Y
Axial) direction. Accordingly, the piezoelectric thin film 72 tends to be displaced in the direction of arrow F ₄ . The vibrating arm 40 generates an electric field in the direction of arrow E when a voltage is applied to each of the electrodes, and the arrow F ₄ again.
In order to be displaced in the direction, the vibrating arm 40 is displaced in the direction of the arrow F ₄ together with the piezoelectric thin film element 101.
In this way, the vibrating arms 30 and 40 are displaced inward as shown in FIG.

When the first state and the second state described above are repeated (that is, an alternating voltage is applied), the vibrating arms 30 and 40 repeat bending vibration in the X-axis direction.

In the first embodiment, the piezoelectric thin film elements 100 and 101 are formed on the surfaces 31 and 41 of the vibrating arms 30 and 40, respectively. However, the piezoelectric thin film elements 100 and 101 are exemplified.
It is good also as a structure formed in the back surfaces 32 and 42 side. At this time, the electrode 51 and the electrode 53, and the electrode 56 and the electrode 58 are replaced.

The vibration characteristics of the piezoelectric thin films 71 and 72 are affected by the crystallinity. there,
A manufacturing method for obtaining good crystallinity will be described.
FIG. 6 is a cross-sectional view showing a part of the first manufacturing method of the crystal resonator according to the present embodiment. Although illustration is omitted, first, a plurality of crystal vibrating pieces 20 are formed on a quartz substrate 11 (sometimes referred to as a quartz wafer) as a large piezoelectric substrate by a photolithography technique. At this time, the base portion 21 or the support portion 22 of the crystal vibrating piece is connected to the crystal substrate 11.

Subsequently, a piezoelectric thin film is formed. Since the piezoelectric thin film 71 and the piezoelectric thin film 72 have the same configuration, the piezoelectric thin film 71 will be described as a representative. As shown in FIG. 6A, a first piezoelectric thin film 71 a is formed at a predetermined position on each surface 31 of the vibrating arm 30. First piezoelectric thin film 71
The formation method of a is PVD (Physical Vapor D) such as RF sputtering.
(eposition) method or CVD (Chemical Vapor De)
position) method. The thickness of the first piezoelectric thin film 71a is 5 nm to
100 nm is preferred.

Subsequently, as shown in FIG. 6B, the first piezoelectric thin film 71a is heat-treated to form a heat-treated first piezoelectric thin film 71b. The heat treatment may be lamp heating or laser light heating, but the heat treatment at 400 ° C. or lower is preferably a heat treatment method in which the temperature can be controlled and the temperature can be raised from a low temperature. Specifically, heat treatment in a heat treatment furnace, hot plate, or vacuum chamber capable of more stable temperature management is preferable. The first piezoelectric thin film 71b after the heat treatment is in a state where crystallization has progressed.

Subsequently, as shown in FIG. 6C, a second piezoelectric thin film 71c is formed on the heat-treated first piezoelectric thin film 71b. The second piezoelectric thin film 71c may be any piezoelectric thin film as long as it is a material that grows crystals on the first piezoelectric thin film 71b after the heat treatment that has been crystallized. In the present embodiment, the first piezoelectric thin film The same material as the thin film 71a is used.

The second piezoelectric thin film 71c can also be formed by a PVD method, a CVD method, or the like, and has a thickness of several μm. The second piezoelectric thin film 71c becomes the piezoelectric thin film 71 including the first piezoelectric thin film 71b after the heat treatment.

After the piezoelectric thin films 71 and 72 are thus formed, the electrodes 51 to 60 are formed. The electrodes 55 and 60 formed on the upper surfaces of the piezoelectric thin films 71 and 72 may be formed simultaneously with other electrodes, or may be formed in a separate process.

After the electrodes 51 to 60 are formed, the crystal substrate 11 is cut by dicing or the like, and the crystal resonator 1
Separate 0 and separate it.

Subsequently, a second manufacturing method of the crystal resonator according to the present embodiment will be described. Since the second manufacturing method is different only in the manufacturing method of the piezoelectric thin film, the manufacturing method of the piezoelectric thin film will be described. Although not shown, reference is made to FIGS.
First, a plurality of crystal vibrating pieces 20 are formed on a large crystal substrate 11 (crystal wafer) by photolithography. At this time, the base 21 or the support 22 of the crystal vibrating piece is attached to the crystal substrate 1.
Connect to 1.

A Pt or Ti metal thin film is formed at predetermined positions on the surfaces 31 and 41 of the vibrating arms 30 and 40 of the quartz substrate 11. These metal films are formed by a sputtering method, a vapor deposition method, or the like.
These metal thin films have a function of promoting crystallization of the piezoelectric thin film.

Subsequently, piezoelectric thin films 71 and 72 are formed on the surface of the metal thin film made of Pt or Ti.
The piezoelectric thin films 71 and 72 have good crystallinity due to the presence of the metal thin film.

The material of the piezoelectric thin films 71 and 72 is compatible with the metal thin film in crystallinity. Specifically, in the structure in which the metal thin film is formed, the material for the piezoelectric thin films 71 and 72 is ZnO.
AlN and GaN are more preferable. However, in the first manufacturing method described above, the material of the piezoelectric thin film 71 is not particularly limited in terms of crystallinity.

Further, the metal thin film may have a structure in which Pt is further laminated on the surface of Ti. In this way, the adhesion at the interface between the piezoelectric thin films 71 and 72 and the quartz crystal vibrating piece 20 is improved and good. Crystallinity can be obtained.

Therefore, according to the first embodiment described above, the quartz crystal vibrating piece 20 and the piezoelectric thin film elements 100 and 10.
1 are connected in series, and the crystal vibrating piece 20 and the piezoelectric thin film elements 100 and 101 are excited by the same excitation signal, and the crystal vibrating piece 20 and the piezoelectric thin film elements 100 and 101 complement each other. As a result, the crystal unit 10 can be downsized in the low frequency region.

Here, the capacitor capacity of the crystal unit 10 that affects the power consumption will be considered.
Capacitor capacity C is expressed as C == dielectric area S, thickness (distance between electrodes) d, and dielectric constant.
It is expressed by ε · S / d. The relationship between the dielectric constant εz of the piezoelectric thin films 71 and 72 and the dielectric constant εq of the quartz is εz >> εq for each material, and the relationship between the thickness dz of the piezoelectric thin films 71 and 72 and the thickness dq of the quartz crystal vibrating piece 20. , Dq >> dz. Therefore, the relationship between the capacitor capacitance Cq of the crystal vibrating piece 20 and the capacitor capacitance Cz of the piezoelectric thin films 71 and 72 is Cz >> Cq.

In the present embodiment, in the equivalent circuit of the oscillator 80, the crystal vibrating piece 20 and the piezoelectric thin film element 1 are used.
00 and 101 are connected in series. Therefore, the capacitor capacity C of the crystal unit 10 is
1 / C = 1 / Cq + 1 / Cz. Here, since Cz >> Cq, C≈Cq
Can be considered. Therefore, the capacitor capacity of the crystal unit 10 can be reduced, and the size of the crystal unit can be reduced without increasing the power consumption.

Further, the electromechanical coupling coefficient K ² of the piezoelectric thin film elements 100 and 101 is larger than the electromechanical coupling coefficient of the quartz crystal vibrating piece 20. The figure of merit M can be expressed by M≈K ² · Q, and the piezoelectric thin film element 100 can be expressed by making the electromechanical coupling coefficient (represented by K ² ) of the piezoelectric thin film elements 100 and 101 larger than that of quartz. , 101 has a high figure of merit M. Accordingly, the larger the electromechanical coupling coefficient is, the easier the vibration is, so that the vibration of the quartz crystal vibrating piece 20 can be made highly efficient by the thin piezoelectric thin films 71 and 72.

In the present embodiment, quartz is used as the piezoelectric vibrating piece. Since quartz is excellent in frequency temperature characteristics, even if the piezoelectric thin films 71 and 72 are supplementarily provided, the satisfactory frequency temperature characteristics of quartz can be utilized.

The vibrating arms 30 and 40 extend along the Y-axis (mechanical axis) direction of the crystal, and the piezoelectric thin films 71 and 72 are formed on the front surfaces 31 and 41 or the rear surfaces 32 and 42 of the vibrating arms 30 and 40, respectively. It is provided on the crystal axis direction side that is divided into two in one or both X-axis (electric axis) directions. Therefore, the vibration modes of the vibrating arms 30 and 40 and the piezoelectric thin film elements 100 and 101 coincide with each other, and the crystal vibrating piece 20 and the piezoelectric thin film elements 100 and 101 can complement each other.

The vibration performance of a vibrator or resonator using a piezoelectric thin film is better as the crystallinity of the piezoelectric thin film is better. The manufacturing method of the crystal unit 10 according to the present embodiment provides the first on the surface of the crystal substrate 11.
After the piezoelectric thin film 71a is formed and the first piezoelectric thin film 71a is heat treated, the second piezoelectric thin film 7 made of the same material as the first piezoelectric thin film 71a is formed on the surface of the heat treated first piezoelectric thin film 71b.
The crystallinity is improved by forming 1c. The second piezoelectric thin film 71c corresponds to the piezoelectric thin film 71 of the present embodiment. Therefore, excellent vibration performance can be obtained by the piezoelectric thin films 71 and 72 having good crystallinity.

As another method for manufacturing the crystal resonator 10 of the present invention, there is a method in which at least one metal thin film of Pt or Ti is formed on the surface of the crystal substrate 11 and the piezoelectric thin film 71 is formed on the surface of the metal thin film. is there. By forming such a metal thin film, the crystallinity of the piezoelectric thin films 71 and 72 can be enhanced.
(Embodiment 2)

Subsequently, Embodiment 2 of the present invention will be described with reference to the drawings. The second embodiment is characterized in that piezoelectric thin films are provided on both the front and back surfaces of the vibrating arm as compared with the first embodiment. Therefore, it demonstrates centering on a different part from Embodiment 1, and attaches | subjects the same code | symbol to the same component.
7 and 8 are cross-sectional views (corresponding to the AA cut plane in FIG. 1) showing the crystal resonator according to the second embodiment. 7 and 8, the surface 31 of the vibrating arm 30 is divided into two in the width direction (X-axis direction), and the crystal axis direction (inner side surface of the vibrating arm 30) with respect to the center line C _{1 of the} vibrating arm 30. The piezoelectric thin film 71 is formed in the (34 direction), and the electrode 51 is formed in the outer direction.

Further, a piezoelectric thin film 73 is formed on the back surface 32 of the vibrating arm 30 so as to face the piezoelectric thin film 71, and an electrode 53 is formed so as to face the electrode 51. In addition, the outer side surface 33 of the vibrating arm 30.
The electrode 52 is formed on the inner side surface 34, the electrode 55 is formed on the surface of the piezoelectric thin film 71, and the electrode 61 is formed on the surface of the piezoelectric thin film 73. Therefore, the piezoelectric thin film 73
Constitutes the piezoelectric thin film element 102 sandwiched between the electrodes 61 and 54.

On the other hand, on the surface 41 of the vibrating arm 40, the width direction (X-axis direction) is divided into _two , and the piezoelectric layer is piezoelectric in the crystal axis direction (the direction of the outer side surface 43 of the vibrating arm 40) relative to the center line C _{2 of the} vibrating arm 40. The body thin film 72 and the electrode 56 are formed in the inner direction.

Further, on the back surface 42 of the vibrating arm 40, a piezoelectric thin film 74 is formed to face the piezoelectric thin film 72, and an electrode 58 is formed to face the electrode 56. Further, the outer side surface 43 of the vibrating arm 40
The electrode 59 is formed on the inner side surface 44, the electrode 60 is formed on the surface of the piezoelectric thin film 72, and the electrode 62 is formed on the surface of the piezoelectric thin film 74. Therefore, the piezoelectric thin film 74
Constitutes the piezoelectric thin film element 103 sandwiched between the electrodes 62 and 59.
The piezoelectric thin films 71 to 74 satisfy the same material conditions as in the first embodiment, and the thickness,
The planar shape is the same.

The electrodes 55, 51, 53, 61, 57, 59 and the connection terminal 93 are connected by a connection electrode 91. Further, the electrodes 52, 54, 58, 62, 60, 56 and the connection terminal 94 are connected by a connection electrode 92. Then, by applying reverse-phase AC voltages to the connection terminals 93 and 94, the vibrating arms 30 and 40 bend and vibrate. Therefore, the electrodes 51 to 62 are excitation electrodes of the crystal vibrating piece 20.

In the crystal resonator 10 configured as described above, in the equivalent circuit of the oscillator, the crystal resonator element 20 and the piezoelectric thin film elements 100 to 103 are connected in series as in the case shown in FIG. .

Next, driving of the crystal resonator according to the present embodiment will be described with reference to the drawings.
FIG. 8 is an explanatory diagram schematically showing a first state of driving of the crystal unit. Electrode 51
, 53, 55, 57, 59, 61 are applied with a negative (−) potential, and the electrodes 52, 54, 5 are applied.
A positive (+) potential is applied to 8, 62, 60, and 56. Here, the crystal axis direction of the quartz crystal of the vibrating arms 30 and 40 is represented by an arrow D, and the polarization direction of the piezoelectric thin films 71 to 74 is represented by an arrow P ₀ .

First, the vibrating arm 30 will be described. The piezoelectric thin films 71 and 73 are contracted in the thickness (Z-axis) direction when the negative potential is applied to the electrodes 55 and 61 and the positive potential is applied to the electrode 54, and the width (X-axis) direction and Extends in the length (Y-axis) direction.

The piezoelectric thin film 73 contracts in the thickness (Z-axis) direction and extends in the width (X-axis) direction and length (Y-axis) direction when a negative potential is applied to the electrode 61 and a positive potential is applied to the electrode 54.

Therefore, the piezoelectric thin film 71 and 73, since it is provided at a position offset in the crystal axis direction of the quartz crystal vibrating arm 30 attempts to displace the vibrating arm 30 in the same way, respectively in direction of arrow F _1. When a voltage is applied to each of the electrodes, the vibrating arm 30 generates an electric field in the direction of arrow E and tends to be displaced in the direction of arrow F ₁ , so that the vibrating arm 30 together with the piezoelectric thin film elements 100 and 102 is in the direction of arrow F _1. It is displaced to.

Next, the vibrating arm 40 will be described. When a positive potential is applied to the electrode 60 and a negative potential is applied to the electrode 59, the piezoelectric thin film 72 extends in the thickness (Z-axis) direction, and the width (X-axis) direction and length (Y
Shrink in the (axis) direction.

Further, when a negative potential is applied to the electrode 59 and a positive potential is applied to the electrode 62, the piezoelectric thin film 74 extends in the thickness (Z-axis) direction and contracts in the width (X-axis) direction and the length (Y-axis) direction.

Accordingly, since the piezoelectric thin films 72 and 74 are provided at positions deviated in the crystal axis direction of the quartz crystal of the vibrating arm 40, the piezoelectric thin films 72 and 74 try to displace the vibrating arm 40 in the direction of the arrow F _{2 in the} same manner. When a voltage is applied to each of the electrodes, the vibrating arm 40 generates an electric field in the direction of arrow E and tends to be displaced in the direction of arrow F ₂ , so that the vibrating arm 40 together with the piezoelectric thin film elements 101 and 103 is in the direction of arrow F _2. It is displaced to.
In this way, the vibrating arms 30 and 40 are displaced in the outer direction (the arrow direction indicated by the solid line in the figure) as shown in FIG.

Next, a second state in which a reverse-phase potential is applied to each electrode with respect to the first state described above will be described. Although illustration is omitted, in the second state, the electrodes 52, 54, 58, 62, 60, 5
A negative potential is applied to 6 and a positive potential is applied to the electrodes 51, 53, 61, 55, 57 and 59. By doing so, the expansion and contraction directions of the piezoelectric thin films 71 to 74 are in the first state (FIG. 8A).
The vibrating arms 30 and 40 are displaced in the direction indicated by the broken line in FIG. 8B.
Therefore, by applying an alternating voltage to the connection terminals 93 and 94, the vibrating arms 30 and 40 continue bending vibration.

Therefore, as described above, by providing the piezoelectric thin films 71 and 73 and the piezoelectric thin films 72 and 74 at the same position in the crystal axis direction of the crystal on both the front and back surfaces of the vibrating arms 30 and 40, the crystal vibrating piece 2
0 and the piezoelectric thin film elements 100 to 103 can complement each other more strongly with each other. In addition, the vibration balance can be achieved as compared with the case where the piezoelectric thin film is formed on one main surface (either one of the front and back surfaces), and unnecessary vibration such as torsion can be reduced.
(Embodiment 3)

Subsequently, Embodiment 3 of the present invention will be described with reference to the drawings. The third embodiment is characterized in that a piezoelectric thin film is provided on the side surface of the vibrating arm as compared with the second embodiment. Therefore, it demonstrates centering on a different part from Embodiment 2, and attaches | subjects the same code | symbol to the same component.
9 and 10 are cross-sectional views (corresponding to the AA cut plane in FIG. 1) showing the crystal resonator according to the third embodiment. 9 and 10, the vibrating arm 30 is formed with piezoelectric thin films 71 and 73 on both the front surface 31 and the back surface 32 and electrodes 55 and 61 on the respective surfaces.

A piezoelectric thin film 75 is provided on the outer side surface 33 of the vibrating arm 30, and an electrode 63 is provided on the surface thereof.
Is formed.
Further, the surface 51 of the vibrating arm 30 has an electrode 51, and the back surface 32 has an electrode 53 facing the electrode 51.
The electrode 54 is formed on the inner side surface 34. Therefore, the piezoelectric thin film 75 is
A piezoelectric thin film element 104 sandwiched between the electrode 63 and the electrodes 51 and 53 is configured.

On the other hand, the vibrating arm 40 has piezoelectric thin films 72 and 74 on both the front surface 41 and the back surface 42, respectively.
Electrodes 60 and 62 are provided on the respective surfaces. A piezoelectric thin film 76 is provided on the inner side surface 44 of the vibrating arm 40, and an electrode 64 is formed on the surface thereof.
Further, the electrode 56 is provided on the front surface 41 of the vibrating arm 40 and the electrode 58 is provided on the back surface 42 so as to face the electrode 56.
The electrode 59 is formed on the outer side surface 43. Therefore, the piezoelectric thin film 76 is
A piezoelectric thin film element 105 sandwiched between the electrode 64 and the electrodes 56 and 58 is configured.
The piezoelectric thin films 75 and 76 are preferably made of the same material as in the first and second embodiments.
The direction of polarization is indicated by an arrow P ₀ in the inner direction of 40.

The electrodes 55, 51, 53, 61, 64, 59 and the connection terminal 93 are connected by a connection electrode 91. Further, the electrodes 63, 54, 58, 62, 60, 56 and the connection terminal 94 are connected by a connection electrode 92. Then, by applying reverse-phase AC voltages to the connection terminals 93 and 94, the vibrating arms 30 and 40 bend and vibrate. Therefore, the electrodes 51 to 64 are excitation electrodes of the crystal vibrating piece 20.

In the crystal resonator 10 configured as described above, in the equivalent circuit of the oscillator, the crystal vibrating piece 20 and the piezoelectric thin film elements 100 to 105 are connected in series as in the case shown in FIG. .

Next, driving of the crystal resonator according to the present embodiment will be described with reference to the drawings.
FIG. 10A is an explanatory diagram schematically showing a first state for driving the crystal resonator.
A negative (−) potential is applied to the electrodes 55, 51, 53, 61, 64 and 59, and the electrodes 63,
A positive (+) potential is applied to 54, 58, 62, 60 and 56. Here, the vibrating arm 30,
The crystal axis direction of 40 quartz is represented by an arrow D, and the polarization direction of the piezoelectric thin films 71 to 76 is represented by an arrow P ₀ .

First, the vibrating arm 30 will be described. The piezoelectric thin film 71 is a state in which the piezoelectric thin film element 100 sandwiched between the electrode 55 and the electrode 54 is formed, and a negative potential is applied to the electrode 55 and a positive potential is applied to the electrode 54. Then, it shrinks in the thickness (Z-axis) direction, and the width (X-axis) direction and length (Y
Axial) direction.

In addition, the piezoelectric thin film 73 is composed of the piezoelectric thin film element 102 sandwiched between the electrode 61 and the electrode 54.
When a negative potential is applied to the electrode 61 and a positive potential is applied to the electrode 54, the electrode 61 contracts in the thickness (Z-axis) direction and extends in the width (X-axis) direction and the length (Y-axis) direction.

The piezoelectric thin film 75 is composed of the piezoelectric thin film element 10 sandwiched between the electrode 63 and the electrodes 51 and 53.
4 is formed, and when a positive potential is applied to the electrode 63 and a negative potential is applied to the electrodes 51 and 53, it extends in the width direction (Z-axis direction), and the thickness direction (X-axis direction) and the length direction (Y-axis) (Direction).

Therefore, the piezoelectric thin film 71, 73, 75 attempts to displace the vibrating arm 30 in the same way, respectively in direction of arrow F _1. When a voltage is applied to each of the electrodes, the vibrating arm 30 generates an electric field in the direction of arrow E and tends to be displaced in the direction of arrow F ₁ , so that the vibrating arm 30 together with the piezoelectric thin film elements 100, 102, 104 is arrow F Displaces in _one direction.

Next, the vibrating arm 40 will be described. The piezoelectric thin film 72 is a state in which the piezoelectric thin film element 101 sandwiched between the electrode 60 and the electrode 59 is formed.
When a negative potential is applied to 9, the film expands in the thickness (Z-axis) direction and contracts in the width (X-axis) direction and length (Y-axis) direction.

The piezoelectric thin film 74 is composed of the piezoelectric thin film element 103 sandwiched between the electrode 62 and the electrode 59.
When a negative potential is applied to the electrode 59 and a positive potential is applied to the electrode 62, it extends in the thickness (Z-axis) direction and contracts in the width (X-axis) direction and length (Y-axis) direction.

The piezoelectric thin film 76 is in a state in which the piezoelectric thin film element 105 sandwiched between the electrode 64 and the electrodes 56 and 58 is formed. When a negative potential is applied to the electrode 64 and a positive potential is applied to the electrodes 56 and 58, the width is reduced. It shrinks in the direction (Z-axis direction) and extends in the thickness direction (X-axis direction) and the length direction (Y-axis direction).

Therefore, the piezoelectric thin-film element 101, 103, 105 attempts to displace the vibrating arm 40 in the arrow F ₂ direction. When a voltage is applied to each of the electrodes, the vibrating arm 40 generates an electric field in the direction of arrow E, and again tends to be displaced in the direction of arrow F ₂ .
With 103 and 105, is displaced in the arrow F ₂ direction.
In this way, the vibrating arms 30 and 40 are displaced in the outer direction (the arrow direction indicated by the solid line in the figure) as shown in FIG.

Next, a description will be given of a second state in which a potential opposite in phase to the first state is applied to each electrode. Although illustration is omitted, in the second state, a positive potential is applied to the electrodes 55, 51, 53, 61, 64, 59, and a negative potential is applied to the electrodes 63, 54, 58, 62, 60, 56. . By doing so, the expansion and contraction direction of the piezoelectric thin films 71 to 76 is in the first state (see FIG. 10A).
The vibrating arms 30 and 40 are displaced in the direction indicated by the broken line in FIG.
Therefore, by applying an alternating voltage to the connection terminals 93 and 94, the vibrating arms 30 and 40 continue bending vibration.

Therefore, according to Embodiment 3 described above, the piezoelectric thin film elements 104 and 105 are also formed on the side surface of the crystal.
By providing this, the vibrations can be complemented more strongly and the vibration efficiency of the crystal unit 10 can be improved.
(Embodiment 4)

Next, Embodiment 4 of the present invention will be described with reference to the drawings. The first embodiment includes the piezoelectric thin film elements 100 and 101, the second embodiment includes the piezoelectric thin film elements 100 to 103, and the third embodiment includes the piezoelectric thin film elements 100 to 105, respectively.

However, by providing the piezoelectric thin film element, the mass balance between the vibrating arm 30 and the vibrating arm 40 with respect to the center line C ₀ of the crystal vibrating piece 20, or the center lines C ₁ and C of the vibrating arms 30 and 40, respectively. _The mass balance for ₂ may be lost. As a result, it is considered that the vibration balance is slightly lost. The fourth embodiment is characterized in that a balance mass is added to solve such a problem.
In addition, the same code | symbol is attached | subjected to the site | part same as Embodiment 1-3.

Fig.11 (a) has shown the example which added balance mass with respect to Embodiment 1 (refer FIG. 2). In FIG. 11 (a), the vibrating arms 30, the piezoelectric thin film 77a as a balance mass serving as the piezoelectric film 71 and the symmetry is provided with respect to the center line C _1. Accordingly, the laminated body of the added piezoelectric thin film 77 a and the electrode 51 is symmetric with respect to the center line C ₁ with respect to the laminated body of the piezoelectric thin film 71 and the electrode 55, and the mass balance is achieved in the vibrating arm 30.

Similarly, in the vibrating arm 40, the piezoelectric thin film 77 b serving as the balance mass is provided, so that the laminated body of the added piezoelectric thin film 77 b and the electrode 56 has the piezoelectric thin film 72 and the electrode 60.
Are symmetrical with respect to the center line C ₂ and the mass line in the vibrating arm 40.

Thus, the piezoelectric thin film 77a as a balance weight, the provision of the 77b, the vibrating arms 30 and 40, take a mass balance with respect to the center line C _0, therefore, can take the vibration balance.

FIG.11 (b) has shown the example which added balance mass with respect to Embodiment 2 (refer FIG. 7). In the second embodiment, piezoelectric thin films 71 and 73 are provided on both front and back surfaces of the vibrating arms 30 and 40, respectively.
Since a structure in which the piezoelectric thin film 72, 74 is provided, the piezoelectric thin film 77a as a symmetrical balance mass to the piezoelectric thin film 71 and 73, the 78a provided to the center line C ₁ in the resonating arm 30 , piezoelectric thin film 77b as a symmetrical balance mass to the piezoelectric thin film 72, 74 with respect to the center line C ₂ on the vibrating arm 40 is provided with 78b.

By providing the balance mass in this way, the mass balance can be achieved in the vibrating arm 30 and the vibrating arm 40, and the mass balance between the vibrating arm 30 and the vibrating arm 40 can be achieved, whereby the vibration balance can be achieved.

FIG.11 (c) has shown the example which added balance mass with respect to Embodiment 3 (refer FIG. 9). Embodiment 3, since a structure in which the piezoelectric thin film 71, 73, 75 are provided on both sides with side surfaces of the vibrating arms 30, the piezoelectric thin film with respect to the center line C ₁ in the resonating arms 30 71 and 73
, 75 are provided with piezoelectric thin films 77a, 78a, 79a as balanced masses symmetrical to each other. Further, since a structure in which the piezoelectric thin film 72, 74, 76 are provided on both sides and the side of the vibrating arm 40, the piezoelectric thin film 72, 74, 76 respectively with respect to the center line C ₂ on the vibrating arm 40 Are provided with piezoelectric thin films 77b, 78b and 79b as symmetrical balance mass.

By providing the balance mass in this way, the mass balance can be achieved in the vibrating arm 30 and the vibrating arm 40, and the mass balance between the vibrating arm 30 and the vibrating arm 40 can be achieved, whereby the vibration balance can be achieved.

In the present embodiment, each of the piezoelectric thin films 77a, 77b, 78a, 78b, 79a, 79b as the balance mass added in FIGS. 11A to 11C described above is replaced with another piezoelectric thin film 71. The same material as ~ 76.

Therefore, according to Embodiment 4 described above, by adding a balance mass corresponding to the piezoelectric thin films 71 to 76, the vibration balance of the vibrating arms 30 and 40 can be balanced, and highly accurate vibration characteristics can be obtained.
Further, by forming the balance mass with the same material as that of the piezoelectric thin film, the balance mass can be configured in the same process as the piezoelectric thin film, so that a highly accurate balance mass can be added. Furthermore, it can be formed using a piezoelectric thin film forming facility.

It should be noted that the present invention is not limited to the above-described embodiment, but includes modifications and improvements as long as the object of the present invention can be achieved.
For example, in the first embodiment described above, the piezoelectric thin films 71 and 72 are formed on the front surfaces 31 and 41 of the vibrating arms 30 and 40, and the piezoelectric thin films 71 and 72 are formed on the back surfaces 32 and 42, respectively. The piezoelectric thin film 71 is formed on the surface 31 of the vibrating arm 30, and the vibrating arm 40 is
The piezoelectric thin film 72 may be formed on the back surface 42 of the substrate, or vice versa.

In the fourth embodiment described above, the balance mass to be added is the same material as that of the piezoelectric thin film, but the balance mass is a mass balance (ie, vibration balance) with respect to the center lines C ₀ , C ₁ , C ₂ . If it can be removed, the material may not be the same, and the material may not be a piezoelectric body.

Therefore, according to the first to fourth embodiments described above, it is possible to provide a highly accurate piezoelectric vibrator that is small in size, low in power consumption.

1 is a perspective view showing a structure of a crystal resonator according to Embodiment 1 of the present invention. Sectional drawing which shows the AA cut surface of FIG. 1, and connection explanatory drawing of each electrode. FIG. 3 is an equivalent circuit diagram illustrating a state in which the crystal resonator according to the first embodiment of the present invention is connected to an oscillation circuit that excites in a specific vibration mode. (A), (b) is explanatory drawing which shows typically a 1st state about the drive of the crystal oscillator based on Embodiment 1 of this invention. (A), (b) is explanatory drawing which shows typically a 2nd state about the drive of the crystal oscillator based on Embodiment 1 of this invention. Sectional drawing which shows a part of 1st manufacturing method which concerns on Embodiment 1 of this invention. Sectional drawing which shows the crystal oscillator which concerns on Embodiment 2 of this invention, and connection explanatory drawing of each electrode. (A), (b) is explanatory drawing which shows typically the drive of the crystal oscillator based on Embodiment 2 of this invention. Sectional drawing which shows the crystal resonator based on Embodiment 3 of this invention, and connection explanatory drawing of each electrode. (A), (b) is explanatory drawing which shows typically the drive of the crystal oscillator based on Embodiment 3 of this invention. (A), (b), (c) is sectional drawing which shows the crystal oscillator based on Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Crystal oscillator, 20 ... Crystal vibrating piece, 21 ... Base, 30, 40 ... Vibrating arm, 31 ... Surface of vibrating arm 30, 32 ... Back surface of vibrating arm 30, 33 ... Outer side surface of vibrating arm 30, 34 ... Vibration arm 3
0 inside surface, 41 ... surface of the vibrating arm 40, 42 ... back surface of the vibrating arm 40, 43 ... outer side surface of the vibrating arm 40, 44 ... inner side surface of the vibrating arm 40, 55, 60 ... electrodes, 71, 72 ... piezoelectric Body thin film,
100, 101... Piezoelectric thin film element.

Claims (3)

The base,
A vibrating arm extending from the base,
The resonating arm has a first surface, a second surface facing the first surface, and a side surface connecting the end portion of the first surface and the end portion of the second surface,
A first electrode is formed on the first surface and the second surface in the extending direction of the vibrating arm,
A second electrode is formed on the side surface in the extending direction of the vibrating arm,
A laminated portion including a piezoelectric layer and a third electrode formed on the piezoelectric layer is formed on at least one of the first surface and the second surface,
The stacked portion is arranged in parallel with the first electrode,
The piezoelectric vibrator according to claim 1, wherein the first electrode and the second electrode have different polarities, and the first electrode and the third electrode have the same polarity .   The piezoelectric vibrator according to claim 1,
  The vibrating arm includes a first vibrating arm and a second vibrating arm,
  The first vibrating arm and the second vibrating arm extend in parallel from the base and have the same electrode arrangement.
  Connecting the first electrode of the first vibrating arm, the third electrode of the first vibrating arm, and the second electrode of the second vibrating arm;
  The piezoelectric vibrator, wherein the second electrode of the first vibrating arm, the first electrode of the second vibrating arm, and the third electrode of the second vibrating arm are connected to each other.   An oscillator comprising: the piezoelectric vibrator according to claim 1; and an amplifier circuit connected to the piezoelectric vibrator.

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