JP5034540B2 - Piezoelectric vibrator, oscillator - Google Patents

Description

The present invention relates to a piezoelectric vibrator having a piezoelectric thin film and a temperature compensation 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 inner side and the outer side from 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 provided on each of these electrodes, and third and fourth electrodes provided on each of these piezoelectric films, 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).

There is also known a tuning fork vibrator in which a ZnO thin film is formed as a piezoelectric thin film on a constant elastic metal material having good frequency temperature characteristics (see, for example, Non-Patent Document 1).

JP 2003-227719 A (Page 9, FIGS. 1 and 2) (Akira Kawabata, Electronics, March 1979, pp. 297-301)

In Patent Document 1 and Non-Patent Document 1 described above, a tuning fork made of metal, silicon, or the like is excited by applying a voltage to the piezoelectric film. In such a structure, in order to obtain a driving force for driving the tuning fork, the thickness of the piezoelectric thin film must be about several μm, and the capacitor capacity increases.
In clock signal applications that always generate signals, there is a problem that power consumption increases.

Further, the piezoelectric thin films exemplified in Patent Document 1 and Non-Patent Document 1 are piezoelectric materials such as ZnO and zirconate titanate, and these piezoelectric materials have a large amount of frequency temperature change.
Therefore, a structure in which a piezoelectric thin film is added to metal, silicon, or quartz having a small frequency temperature change is conceivable. However, there is a problem that the amount of change in frequency temperature is increased due to the influence of the primary temperature coefficient of the piezoelectric thin film.

An object of the present invention is to provide a highly accurate piezoelectric vibrator that is small in size, consumes less power and has a small amount of frequency temperature change, and a method for manufacturing the piezoelectric vibrator.

The piezoelectric vibrator according to the present invention includes a base, at least a pair of vibrating arms extending in parallel from the base, and excitation electrodes having different polarities provided on opposing main surfaces or side surfaces of the pair of vibrating arms. And a piezoelectric thin film that is connected in series with the piezoelectric vibrating piece and provided on at least one surface of the opposing main surface or side surface, and an excitation electrode formed on the surface of the piezoelectric thin film And a temperature compensation film provided on the surface of the excitation electrode formed on the surface of the piezoelectric thin film and having a primary temperature coefficient opposite to the primary temperature coefficient of the piezoelectric thin film. It is characterized by being provided. 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 on at least one of the first surface and the second surface, a piezoelectric layer, a temperature compensation layer, a third electrode, The laminated 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 have polarities The sign of the primary temperature coefficient of the temperature compensation layer is opposite to the sign of the primary temperature coefficient of the piezoelectric layer. And wherein the door. Further, the temperature compensation layer is formed of any member of Ni-Fe alloy, silicon oxide, teryl oxide, and zirconium oxide. 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. Connecting the first electrode of the vibrating arm, the third electrode of the first vibrating arm, and the second electrode of the second vibrating arm, and 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. Further, the oscillator includes the piezoelectric vibrator and an amplifier circuit connected to the 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.

Further, a temperature compensation film having a primary temperature coefficient opposite to that of the piezoelectric thin film is provided on the surface of the piezoelectric thin film, and the primary temperature coefficient of the piezoelectric thin film is canceled out. Therefore, the piezoelectric vibrator by providing the piezoelectric thin film The primary frequency change in temperature can be reduced, and a highly accurate piezoelectric vibrator can be realized.

Further, the configuration in which the temperature compensation film is provided on the surface of the excitation electrode formed on the surface of the piezoelectric thin film will be described in detail in an embodiment described later, but the primary frequency temperature variation with respect to the thickness of the temperature compensation film is Since it is insensitive, there is an advantage that fine adjustment of the primary frequency temperature change amount can be easily performed. Further, it is easy to form a temperature compensation film, and the mass production stability is excellent.

Further, the piezoelectric vibrator of the present invention has a base portion, at least a pair of vibrating arms extending in parallel from the base portion, and different polarities provided on the opposing main surface or side surface of each of the pair of vibrating arms. A piezoelectric vibrating piece having an excitation electrode; a piezoelectric thin film connected in series with the piezoelectric vibrating piece; provided on at least one surface of the opposing main surface or side surface; and provided on a surface of the piezoelectric thin film; A piezoelectric thin film element having a temperature compensation film having a primary temperature coefficient opposite to a primary temperature coefficient of the piezoelectric thin film and an excitation electrode provided on the surface of the temperature compensation film is provided. And

According to the present invention, since the piezoelectric vibrating piece includes the piezoelectric thin film element having the temperature compensation film, the temperature compensation film is provided on the upper surface of the excitation electrode as described above in detail in an embodiment described later. Since the primary frequency temperature change with respect to the thickness of the temperature compensation film is more sensitive than the structure to be formed, it is possible to adjust the primary frequency temperature change over a wide range with thinner film formation, and the productivity of film formation There is an advantage that is high.

  The piezoelectric vibrating piece is preferably a quartz vibrating piece.

The quartz crystal vibrating piece is more excellent in frequency temperature characteristics than piezoelectric vibrating pieces made of other piezoelectric materials.
Therefore, even in a structure using a piezoelectric thin film, the excellent frequency temperature characteristics inherent in quartz can be utilized by providing the temperature compensation film as described above.

  It is desirable that a balance mass is added to the vibrating arm.

By providing the piezoelectric thin film and the temperature compensation film 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 added mass of the piezoelectric thin film and the temperature compensation film, it is possible to balance the vibration of the vibrating arm and maintain highly accurate vibration characteristics.

The method for manufacturing a piezoelectric vibrator of the present invention includes a step of forming a piezoelectric thin film on a surface of a piezoelectric substrate, a step of forming a temperature compensation film on the surface of the piezoelectric thin film, and a film thickness of the temperature compensation film. And adjusting the primary temperature coefficient by adjusting the thickness.

The primary temperature coefficient of the piezoelectric vibrator having the piezoelectric thin film is affected by the thickness of the temperature compensation film. Therefore, the piezoelectric vibrator can be adjusted to an appropriate primary temperature coefficient by increasing or decreasing the thickness of the temperature compensation film.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 7 show the piezoelectric vibrator according to the first embodiment of the present invention, and FIGS. 8 to 10 show the second embodiment.
11 shows the third embodiment, FIG. 12 shows the fourth embodiment, and FIG. 13 shows the fifth embodiment.
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 is not limited as long as it has piezoelectric performance, but in the following embodiments, a quartz vibrator having excellent frequency temperature characteristics is exemplified as the piezoelectric vibrator. I will explain. FIG.
In FIG. 2, the crystal resonator 10 includes a plurality of electrodes on the surface of the crystal resonator element 20, piezoelectric thin film elements 100 and 101, and temperature compensation films 110 and 111 provided on the upper surfaces of the piezoelectric thin film elements 100 and 101, respectively. And is configured.

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 vibration 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 (inward direction of the vibration arm , or piezoelectric thin film in a first region) (piezoelectric layer) 71, an outer direction (second region) to the electrode (first electrode) 51 is formed, the main surface facing the surface 31 (second surface) 32 (hereinafter The 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, respectively, or 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. Further, an electrode (third electrode) 55 is formed on the surface of the piezoelectric thin film 71, and a temperature compensation film (temperature compensation layer) 110 is provided on the upper surface of the electrode 55.

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 with respect to the center line C2 of the vibrating arm 40 (the outer direction of the vibrating arm, or piezoelectric thin film in the second region) (piezoelectric layer) 72, the electrode (first electrode) 56 is formed on the inner side direction (first region), the other main surface (second surface) 42 (hereinafter, the back surface 42 The electrode (first electrode) 58 is formed. The electrode 58 may be divided into two so as to face the piezoelectric thin film 72 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. Further, an electrode (third electrode) 60 is formed on the surface of the piezoelectric thin film 72, and a temperature compensation film (temperature compensation layer) 111 is provided on the upper surface of the electrode 60.

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.

Further, as a material of the temperature compensation films 110 and 111, Ni-iron alloy, silicon oxide, teryl oxide, zirconium oxide or the like can be adopted, and the primary temperature coefficient opposite to the primary temperature coefficient of the piezoelectric thin films 71 and 72 is obtained. Choose from what you have. Specifically, when the piezoelectric thin films 71 and 72 have a negative primary temperature coefficient, the temperature compensation films 110 and 111 have a positive primary temperature coefficient.

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 oscillator 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.
FIG. 4 is an explanatory diagram schematically showing driving of the crystal resonator. FIG. 4 shows the AA cut surface 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 (illustration is omitted). 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, 53,
A positive (+) potential is applied to 55, 57 and 59, and a negative (−) potential is applied to the electrodes 52, 54, 56, 58 and 60.

First, the vibrating arm 30 will be described. When a positive potential is applied to the electrode 55 and a negative 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
0, for the application of a voltage to each electrode and the first state (FIG. 4 (a), reference) electric field is generated in the opposite direction to the attempts also displaced in the arrow F ₃ direction, the vibrating arm 30 is a piezoelectric with body thin film element 100, displaced in the arrow F ₃ direction.

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 . Vibrating arms 40, since the first state by applying a voltage to each electrode (FIG. 4 (a), reference) electric field is generated in the opposite direction to the still attempts to displace the arrow F ₄ direction, vibrating arms 40 Is displaced in the direction of arrow F ₄ together with the piezoelectric thin film element 101.

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.
May be formed on the back surfaces 32 and 42. At this time, the electrode 51, the electrode 53, and the electrode 5
6 and the electrode 58 are interchanged.

Next, the temperature compensation films 110 and 111 will be described.
FIG. 5 is a graph schematically showing the relationship between the temperature of the temperature compensation films 110 and 111 and the primary frequency temperature variation, that is, the primary temperature coefficient. Here, the primary temperature coefficient df / f of the piezoelectric thin films 71 and 72 has a negative slope (specifically −40 ppm / deg). Therefore, the primary temperature coefficient df / f of the temperature compensation films 110 and 111 is set to a positive slope (specifically +40 ppm /
deg), the primary temperature coefficient df / f of the piezoelectric thin film can be set to “0”.

Next, the influence of the primary temperature coefficient of the piezoelectric thin films 71 and 72 on the crystal resonator will be described.
FIG. 6 is a graph schematically showing a frequency change amount (frequency temperature characteristic) with respect to a temperature change of the crystal resonator. In FIG. 6, the frequency-temperature characteristic of the crystal unit 10 (represented by a solid line in the figure).
Is represented by a quadratic curve with apex temperature T ₀ . Here, the piezoelectric thin film 71 is applied to the crystal unit 10.
, 72 is added, the frequency temperature characteristic is represented by a quadratic curve (represented by a broken line in the figure) in which the vertex temperature T ₀ moves in the minus direction and has the vertex temperature T ₁ . Therefore, it is necessary to compensate for the original crystal resonator frequency temperature characteristic (secondary curve of the vertex temperature T ₁ ), and the temperature compensation film 110,
111 is provided. The primary temperature coefficient of the temperature compensation film varies depending on the material and the film thickness.

FIG. 7 is a graph showing the relationship between the thickness h of the temperature compensation film and the primary frequency temperature change amount df / f when the temperature compensation films 110 and 111 are provided on the crystal vibrating piece 20. Here, the material of the temperature compensation films 110 and 111 is silicon oxide (SiO ₂ ). In FIG. 7, the primary frequency temperature variation df / f increases as the film thickness h of the temperature compensation films 110 and 111 increases. Therefore, if the film thickness h (specifically around 550 nm) at which the primary frequency temperature change amount is “0”, the influence of the primary temperature coefficient of the piezoelectric thin films 71 and 72 can be eliminated. The frequency temperature characteristic of the apex temperature T ₀ shown in FIG. 6 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, so that the crystal vibrating piece 20 and the piezoelectric thin film elements 100 and 101 complement each other. Accordingly, the quartz resonator 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 if dielectric area S, thickness (distance between electrodes) d, and dielectric constant ε.
= 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 total capacitor capacity C of the crystal unit 10 is expressed by 1 / C = 1 / Cq + 1 / Cz. Here, since Cz >> Cq, C≈C
q can be considered. Thus, the total capacitor capacity C 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 this embodiment, a crystal resonator is used as the piezoelectric vibrating piece, and the piezoelectric thin films 71 and 72 are used.
Temperature compensation films 110, 11 having a primary temperature coefficient opposite to that of the piezoelectric thin films 71, 72 on the surface thereof.
1 is cancelled, the primary temperature coefficient of the piezoelectric thin films 71 and 72 is cancelled. Therefore, even if the piezoelectric thin film is used, the excellent frequency temperature characteristics inherent in the crystal unit 10 can be utilized.
(Embodiment 2)

Subsequently, Embodiment 2 of the present invention will be described with reference to the drawings. The second embodiment is characterized in that a temperature compensation film is provided between the piezoelectric thin film and the electrode (that is, the upper surface of the piezoelectric thin film element) as compared with the first embodiment described above. Therefore, the description will focus on the differences, and the first embodiment will be described.
The same reference numerals are used for explanation.
FIG. 8 is a cross-sectional view of the crystal resonator according to the second embodiment (corresponding to the AA cut surface of FIG. 1) and a connection explanatory diagram of each electrode. In FIG. 8, a piezoelectric thin film 71 on the surface 31 of the vibrating arm 30,
A temperature compensation film 110 is provided on the surface of the piezoelectric thin film 71, and an electrode 55 is provided on the surface of the temperature compensation film 110.

Accordingly, the piezoelectric thin film 71 and the temperature compensation film 110 constitute a piezoelectric thin film element 100 sandwiched between the electrode 55 and the electrode 54 with a part of the vibrating arm 30 interposed therebetween. .

A piezoelectric thin film 72 is provided on the surface 41 of the vibrating arm 40, a temperature compensation film 111 is provided on the surface of the piezoelectric thin film 72, and an electrode 60 is provided on the upper surface of the temperature compensation film 111.

Accordingly, the piezoelectric thin film 72 and the temperature compensation film 111 constitute a piezoelectric thin film element 101 sandwiched between the electrode 60 and the electrode 59 with a part of the vibrating arm 40 interposed therebetween. .

The electrodes 51 to 60 and the connection terminals 93 and 94 are connected in the same manner as in the first embodiment. By applying an AC voltage to the connection terminals 93 and 94, the vibrating arms 30 and 40 are bent. Vibrate.

FIG. 9 is an explanatory diagram schematically showing driving of the crystal unit. 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. When a negative potential is applied to the electrode 55 and a positive potential is applied to the electrode 54, the vibrating arm 30 contracts in the thickness (Z-axis) direction and extends in the width (X-axis) direction and the length (Y-axis) direction.

Therefore, since the piezoelectric thin film element 100 is provided at a position deviated in the crystal axis direction of the crystal, the vibrating arm 30 tends to be displaced in the direction of the 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. When a positive potential is applied to the electrode 60 and a negative potential is applied to the electrode 59, the electrode 60 extends in the thickness (Z-axis) direction and contracts in the width (X-axis) direction and the length (Y-axis) direction.

Therefore, since the piezoelectric thin film element 101 is provided at a position deviated in the crystal axis direction of the crystal, the vibrating arm 40 tends to be displaced 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 outward (arrow F) as shown in FIG.
_1, displaced in the F ₂ direction).

Next, the second state will be described (illustration is omitted). 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, 53,
A positive (+) potential is applied to 55, 57 and 59, and a negative (−) potential is applied to the electrodes 52, 54, 56, 58 and 60.

First, the vibrating arm 30 will be described. When a positive potential is applied to the electrode 55 and a negative 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.

Therefore, the piezoelectric thin film element 100 tries to displace the vibrating arm 30 in the direction of the arrow F ₃ shown in FIG. When a voltage is applied to each of the electrodes, the vibrating arm 30 generates an electric field in the direction opposite to the arrow E in FIG. 9 and tends to be displaced in the direction of the arrow F _3.
With 00, is displaced in the arrow F ₃ direction.

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.

Therefore, the piezoelectric thin film element 101 tends to be displaced in the direction of arrow F ₄ . The vibrating arm 40 is
When a voltage is applied to each electrode, an electric field is generated in the direction opposite to the arrow E in FIG.
_In order to displace in _four directions, the vibrating arm 40 is displaced in the direction of arrow F ₄ together with the piezoelectric thin film element 101.

When an AC voltage is applied to the connection terminals 93 and 94 and the first state and the second state described above are repeated, the vibrating arms 30 and 40 repeat bending vibration in the X-axis direction as shown in FIG. 9B. .

Next, temperature compensation by the configuration of the second embodiment in which the temperature compensation films 110 and 111 are provided between the electrodes 55 and 60 and the piezoelectric thin films 71 and 72 will be described. Even in such a configuration, the primary temperature coefficient of the temperature compensation films 110 and 111 varies depending on the material and the film thickness.

FIG. 10 is a graph showing the relationship between the thickness h of the temperature compensation film and the primary frequency temperature variation df / f when the temperature compensation films 110 and 111 are provided on the crystal vibrating piece 20. Here, the material of the temperature compensation film 110 is silicon oxide (SiO ₂ ). In addition, the comparison with the structure of Embodiment 1 is represented. In FIG. 10, the primary frequency temperature variation increases as the film thickness h of the temperature compensation films 110 and 111 increases.

Here, in the configuration of the second embodiment (from the upper layer to the electrode-temperature compensation film-piezoelectric thin film), the film thickness is larger than that in the configuration of the first embodiment (from the upper layer to the temperature compensation film-electrode-piezoelectric thin film). The first-order frequency temperature variation (df / f) changes sensitively. Then, it is shown that the influence of the primary temperature coefficient of the piezoelectric thin film can be eliminated by setting the film thickness h (specifically around 50 nm) at which the primary frequency temperature change amount is “0”.

With reference to FIG. 10, the difference in characteristics according to the configurations of the first embodiment and the second embodiment is compared. According to the first embodiment, the primary frequency temperature change amount df / f is insensitive to the film thickness h, and even if the film thickness h changes, the primary frequency temperature change amount df / f is small. There is an effect of excellent mass production stability.

Further, according to the second embodiment, the primary frequency temperature change amount df / f is sensitive to the film thickness h, and the film thickness h may be as thin as 50 nm. Therefore, the film formation time can be shortened, and the film stress due to film formation can be reduced, so that there is an effect that deformation such as warpage of the piezoelectric vibrating reed hardly occurs.

Further, in the structures according to the first and second embodiments, by increasing or decreasing the film thickness h of the temperature compensation films 110 and 111, as shown in FIG. 10, the primary frequency temperature change amount df / f (that is, the primary temperature change amount) Temperature coefficient) can be adjusted. Here, a method for manufacturing a crystal resonator including a method for adjusting the film thickness h of the temperature compensation films 110 and 111 will be described. Illustration is omitted.

First, a plurality of crystal vibrating pieces 20 are formed on a quartz substrate (sometimes called a quartz wafer) as a large piezoelectric substrate by photolithography. At this time, the base portion 21 or the support portion 22 (see FIG. 1) of the crystal vibrating piece is connected to the crystal substrate.

Subsequently, piezoelectric thin films 71 and 72 are formed. In the structure of the first embodiment, the vibrating arms 30 and 40 are provided.
A first piezoelectric thin film is formed at a predetermined position on each of the surfaces 31 and 41. The first piezoelectric thin film is formed by PVD (Physical Vapor Dep) such as RF sputtering.
oxidization) method, or CVD (Chemical Vapor Depo)
(situation) method. The thickness of the first piezoelectric thin film is 5 nm to 100 nm.
Is preferred.

Subsequently, the first piezoelectric thin film is heat treated to form a heat treated first piezoelectric thin film. 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 after the heat treatment is in a state where crystallization has progressed.

Subsequently, a second piezoelectric thin film is formed on the first piezoelectric thin film after the heat treatment. The second piezoelectric thin film may be any piezoelectric thin film as long as it is a material that grows crystals on the first piezoelectric thin film after the heat treatment that has been crystallized. In the present embodiment, The same material is used.

The second piezoelectric thin film can also be formed by a film forming method such as a PVD method or a CVD method, and the thickness thereof is several μm. The second piezoelectric thin film becomes the piezoelectric thin films 71 and 72 including the first piezoelectric thin film 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 separate steps.

After forming the electrodes 51 to 60, the temperature compensation films 110 and 111 are formed. Temperature compensation film 11
0 and 111 are formed in the chamber by a film forming method such as a PVD method or a CVD method. During this film formation process, a frequency measurement monitor is provided in the chamber, and the film thickness h at which the primary frequency temperature change amount is “0” is adjusted while monitoring the primary temperature coefficient.

Alternatively, as a method of obtaining a film thickness h in which the primary frequency temperature change amount df / f is “0” by forming the film thickness in a thick direction in advance and grinding the surface of the temperature compensation film by etching or the like. Also good.

Then, after the temperature compensation films 110 and 111 are formed, the crystal substrate 11 is cut by dicing or the like, and the crystal resonator 10 is separated and separated into individual pieces.

In the structure of the second embodiment, the temperature compensation films 110 and 1 are formed after the piezoelectric thin films 71 and 72 are formed.
11 and electrodes 55 and 60 are formed on the upper surfaces of the temperature compensation films 110 and 111. The formation method of the piezoelectric thin films 71 and 72 and the temperature compensation films 110 and 111 is the same as the method of the first embodiment described above. Further, in the film forming process of the temperature compensation films 110 and 111, the primary temperature coefficient is monitored.

As a method for improving the crystallinity of the piezoelectric thin film, a method of forming the piezoelectric thin film on the surface of the metal thin film can be employed. In this method, 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, and piezoelectric thin films 71 and 72 are formed on the surface of the metal thin film. The piezoelectric thin films 71 and 72 have good crystallinity due to the presence of the metal thin film.

The vibration characteristics of the piezoelectric thin film are better as the crystallinity of the piezoelectric thin film is better. Therefore, after forming the first piezoelectric thin film on the surface of the quartz substrate, heat-treating the first piezoelectric thin film, the first piezoelectric thin film is made of the same material as the first piezoelectric thin film on the surface of the heat-treated first piezoelectric thin film. (2) A piezoelectric thin film is formed to improve crystallinity. As a result, excellent vibration performance can be obtained.

Further, by forming at least one metal thin film of Pt or Ti on the surface of the quartz substrate and forming the piezoelectric thin films 71 and 72 on the surface of the metal thin film, the crystallinity of the piezoelectric thin films 71 and 72 is enhanced. In addition, there is an effect that the adhesion between the piezoelectric thin films 71 and 72 and the crystal vibrating piece 20 can be enhanced.

Further, during the film forming process of the temperature compensation films 110 and 111, a frequency measurement monitor is provided in the chamber, and the film thickness at which the primary frequency temperature change amount is “0” while monitoring the primary temperature coefficient in the chamber. A crystal oscillator with high productivity can be realized by the method of obtaining the length h.
(Embodiment 3)

Subsequently, a crystal resonator according to a third embodiment of the present invention will be described with reference to the drawings. The third embodiment is characterized in that piezoelectric thin film elements are formed on both front and back surfaces of the vibrating arms 30 and 40, respectively. Therefore, it demonstrates centering on a different part from Embodiment 1, and attaches | subjects the same code | symbol to the same site | part.
FIG. 11 is a cross-sectional view schematically showing the configuration and driving of the crystal resonator according to the third embodiment. 11 illustrates the configuration of the piezoelectric thin film-electrode-temperature compensation film described in the first embodiment.
In FIG. 11, a piezoelectric thin film element 102 is formed on the back surface 32 of the vibrating arm 30 so as to face the piezoelectric thin film element 100.

The configuration of the piezoelectric thin film element 102 is the same as that of the piezoelectric thin film element 101, and the piezoelectric thin film 73, the electrode 61, and the temperature compensation film 112 are laminated in this order from the back surface 32 of the vibrating arm 30.
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 back surface 42 of the vibrating arm 40, the piezoelectric thin film element 1 faces the piezoelectric thin film element 101.
03, and an electrode 58 is formed to face the electrode 56. 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.

Next, driving of the crystal vibrating piece 20 will be described. Electrodes 51, 53, 55, 57, 59,
A negative (−) potential is applied to 61, and a positive (+) potential is applied to the electrodes 52, 54, 58, 62, 60 and 56.

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

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 axial 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 expands in the thickness (Z-axis) direction and contracts in the width (X-axis) direction and 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 moved outward (arrows F ₁ ,
Displaced in the F ₂ direction).

Next, a case where a reverse phase potential is applied to each electrode in the state shown in FIG. 11 will be described. Illustration is omitted. A negative potential is applied to the electrodes 52, 54, 58, 62, 60 and 56, and a positive potential is applied to the electrodes 51, 53, 61, 55, 57 and 59. By doing so, the expansion and contraction direction of the piezoelectric thin films 71 to 74 is opposite to the state shown in FIG.
The vibrating arms 30 and 40 are displaced in the directions of arrows F ₃ and F _{4 shown} in FIG.
Accordingly, by applying an AC voltage to the connection terminals 93 and 94, the resonating arms 30 and 40 can be connected to each other as shown in FIG.
As shown in (b), the bending vibration is continued in the X-axis direction.

Therefore, as described above, the piezoelectric thin films 71 and 7 on both the front and back surfaces of the vibrating arms 30 and 40, respectively.
3 and the piezoelectric thin films 72 and 74, the crystal vibrating piece 20 and the piezoelectric thin film element 1 are provided.
00 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.

Also in the structure of the third embodiment, since the temperature compensation films 110 to 113 are provided, the influence of the primary frequency temperature change amount df / f due to the provision of the piezoelectric thin films 71 to 74 can be eliminated.
(Embodiment 4)

Next, a fourth embodiment of the present invention will be described with reference to the drawings. The fourth embodiment is characterized in that a piezoelectric thin film element is also provided on the side surface of the vibrating arm as compared with the third embodiment. Therefore, it demonstrates centering on a different part from Embodiment 3, and the same code | symbol as Embodiment 3 is attached | subjected to the common part.
FIG. 12 is a cross-sectional view schematically illustrating the configuration and driving of the crystal resonator according to the fourth embodiment. FIG. 12 illustrates the configuration of the piezoelectric thin film-electrode-temperature compensation film described in the first embodiment.
In FIG. 12, a piezoelectric thin film element 104 is formed on the outer side surface 33 of the vibrating arm 30.

The configuration of the piezoelectric thin film element 104 is the same as that of the piezoelectric thin film elements 100 to 103, and the piezoelectric thin film 75, the electrode 63, and the temperature compensation film 114 are laminated in this order from the outer side surface 33 of the vibrating arm 30.
Therefore, the piezoelectric thin film 75 constitutes the piezoelectric thin film element 104 sandwiched between the electrode 63 and the electrodes 51 and 53.

On the other hand, a piezoelectric thin film element 105 is formed on the inner side surface 44 of the vibrating arm 40. The configuration of the piezoelectric thin film element 105 is the same as that of the piezoelectric thin film element 104, and the piezoelectric thin film 76, the electrode 64, and the temperature compensation film 115 are laminated in this order from the inner side surface 44 of the vibrating arm 40. Accordingly, the piezoelectric thin film 76 has the piezoelectric thin film element 10 sandwiched between the electrode 64 and the electrodes 56 and 58.
5 is configured.
The piezoelectric thin films 71 to 76 satisfy the same conditions as the material as in the first embodiment, and have a thickness,
The planar shape is the same.

Next, driving of the crystal vibrating piece 20 will be described. Electrodes 51, 53, 55, 61, 59,
A negative (−) potential is applied to 64, and a positive (+) potential is applied to the electrodes 54, 63, 58, 62, 60 and 56.

First, the vibrating arm 30 will be described. The expansion and contraction of the piezoelectric thin films 71 and 73 is the same as that of the third embodiment described above, and contracts in the thickness (Z-axis) direction, and the width (X-axis) direction and length (Y Axial) direction.

The piezoelectric thin film 75 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 electrodes 51 and 53 and a positive potential is applied to the electrode 63. .

Therefore, the piezoelectric thin film 71, 73, 75 attempts to displace the vibrating arms 30 to 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 also tends to be displaced in the direction of arrow F ₁ , so that the vibrating arm 30 has the piezoelectric thin film elements 100, 102, 1.
With 04 displaced in direction of arrow F _1.

Next, the vibrating arm 40 will be described. The expansion and contraction of the piezoelectric thin films 72 and 74 is the same as in Embodiment 3 described above, and 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 extends in the thickness (Z-axis) direction and contracts in the width (X-axis) direction and length (Y-axis direction) when a negative potential is applied to the electrode 64 and a positive potential is applied to the electrodes 56 and 58. .

Therefore, the piezoelectric thin film 72, 74, tries 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 also tends to be displaced in the direction of arrow F ₂ , so that the vibrating arm 40 has the piezoelectric thin film elements 101, 103, 1.
With 05, is displaced in the arrow F ₂ direction.
In this way, the vibrating arms 30 and 40 are displaced outward as shown in FIG.

Next, a reverse-phase potential is applied to each electrode with respect to the state shown in FIG. Although not shown, the electrodes 51, 53, 61, 55, 59, and 64 have a positive potential, and the electrodes 54, 63, and 5
A negative potential voltage is applied to 6,58,62,60. By doing so, the expansion and contraction direction of the piezoelectric thin films 71 to 76 is opposite to the direction shown in FIG. 12A, and the vibrating arms 30 and 40 are displaced in the directions of arrows F ₃ and F ₄ .
Therefore, by applying an AC voltage to the connection terminals 93 and 94, the resonating arms 30 and 40 are connected to each other as shown in FIG.
As shown in (b), the bending vibration is continued in the X-axis direction.

Therefore, according to the fourth embodiment described above, by providing the piezoelectric thin films 75 and 76 also in the thickness direction of the crystal (Z-axis direction, side surface of the vibrating arm), it is possible to complement the vibrations more strongly and mutually. This can increase the vibration efficiency of the crystal resonator.

Also in the structure of the fourth embodiment, since the temperature compensation films 110 to 115 are provided, the influence of the primary frequency temperature change amount due to the provision of the piezoelectric thin films 71 to 76 can be eliminated.
(Embodiment 5)

Next, Embodiment 5 of the present invention will be described with reference to the drawings. Embodiment 1 described above
2, piezoelectric thin film elements 100 and 101, and in the third embodiment, piezoelectric thin film elements 100 to 103,
In the fourth embodiment, the piezoelectric thin film elements 100 to 105 are provided.

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 fifth 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 1-4. The balance mass is the same material as the piezoelectric thin film.

13A to 13C are cross-sectional views illustrating the crystal resonator according to the fifth embodiment. Note that the structures illustrated in FIGS. 13A to 13C illustrate the configuration of the temperature compensation film described in the first embodiment.
FIG. 13A shows an example in which a balance mass is added to the structure described in the first embodiment (see FIG. 2). In FIG. 13 (a), the vibrating arms 30, balance weight 77a as a piezoelectric thin film element 100 and symmetry are provided with respect to the center line C _1. That is, the balance mass 77a is such that the total mass of the temperature compensation film 110, the electrode 55, and the piezoelectric thin film 71 is equal to the total mass of the balance mass 77a and the electrode 51. Therefore, a mass balance can be achieved in the vibrating arm 30.

Similarly, in the vibrating arm 40, by providing the balance mass 77b, the total mass of the laminated body of the added balance mass 77b and the electrode 56 is the same as that of the laminated body of the piezoelectric thin film 72, the electrode 60, and the temperature compensation film 111. The mass sum is equal to the center line C ₂ and is symmetric with respect to the center line C ₂ .

Thus, by providing the balance masses 77a and 77b, the vibrating arms 30 and 40 are
The mass balance is also achieved with respect to the center line C ₀ , and the vibration balance can be achieved.

FIG.13 (b) has shown the example which added balance mass with respect to Embodiment 3 (refer FIG. 11). In the third embodiment, the piezoelectric thin film element 10 is provided on each of the front and back surfaces of the vibrating arms 30 and 40.
0, 102, and piezoelectric thin film elements 101, 103 are provided. Symmetrical balance mass 77a in the piezoelectric thin film element 100, 102 with respect to the center line C ₁ in the resonating arm 30, 78
provided a, the vibrating arm 40 is provided balance mass 77b is symmetrical to the piezoelectric thin-film element 101, 103 relative to the center line C _2, and 78b.

Thus, by providing the balance masses 77a and 77b and the balance masses 78a and 78b, the mass balance can be achieved in the vibrating arm 30 and the vibrating arm 40, and the vibrating arm 30 can be balanced.
And the vibrating arm 40 are balanced in mass, and thereby balanced in vibration.

FIG.13 (c) has shown the example which added balance mass with respect to Embodiment 4 (refer FIG. 12). In the fourth embodiment, the piezoelectric thin film element 100 is provided on each of the front and back surfaces and side surfaces of the vibrating arm 30.
Since in structures 102, 104 are provided, symmetrical balance mass 77a to each piezoelectric thin-film element 100, 102, 104 with respect to the center line C ₁ in the resonating arm 30, 78a,
79a is provided.

Further, the piezoelectric thin film elements 101, 103, 1 are provided on both the front and back surfaces and the side surfaces of the vibrating arm 40.
Since a structure in which 05 is provided, the piezoelectric thin-film element with respect to the center line C ₂ 101,10
3 and 105 are provided with symmetrical balance masses 77b, 78b, 79b, respectively.

Thus, by providing the balance masses 77a and 77b, the balance masses 78a and 78b, and the balance masses 79a and 79b, the mass balance can be achieved in the vibrating arm 30 and the vibrating arm 40, and the mass of the vibrating arm 30 and the vibrating arm 40 can be maintained. There is a balance, which allows a vibration balance.

The above-described second embodiment has a structure in which the temperature compensation films 110 and 111 are provided between the electrodes 55 and 60 and the piezoelectric thin films 71 and 72, respectively. By adding balance masses 77a and 77b, balance masses 78a and 78b, and balance masses 79a and 79b shown in FIG. 13C, mass balance can be achieved.

Therefore, according to the fifth embodiment described above, by adding a balance mass corresponding to the piezoelectric thin film elements 100 to 105, the vibration arms 30 and 40 are balanced in vibration, and highly accurate vibration characteristics can be obtained. it can.
Further, if the balance mass is formed of the same material as the piezoelectric thin film, the balance mass can be configured with the same device as the piezoelectric thin film, so that a highly accurate balance mass can be added.

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 rear surfaces 32 and 42, respectively. As described above, the piezoelectric thin film 71 may be formed on the front surface 31 of the vibrating arm 30, and the piezoelectric thin film 72 may be formed on the back surface 42 of the vibrating arm 40, or vice versa.

In the fifth 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 fifth embodiments described above, by providing a piezoelectric thin film element on the crystal vibrating piece, it is possible to reduce the size and power consumption of the crystal resonator, and further by providing a temperature compensation film. In addition, it is possible to provide a high-accuracy crystal resonator with a small amount of frequency temperature change.

1 is a perspective view showing a structure of a piezoelectric vibrator 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. FIG. 3 is an explanatory diagram schematically illustrating driving of the crystal resonator according to the first embodiment of the invention. The graph which shows the relationship between the temperature of the temperature compensation film which concerns on Embodiment 1 of this invention, and a primary frequency variation | change_quantity. 3 is a graph schematically showing a frequency change amount with respect to a temperature change of the crystal resonator according to the first embodiment of the invention. 6 is a graph showing the relationship between the thickness h of the temperature compensation film of the crystal resonator according to the first embodiment of the present invention and the primary frequency temperature change amount. Sectional drawing of the crystal oscillator which concerns on Embodiment 2 of this invention, and connection explanatory drawing of each electrode. Explanatory drawing which shows typically about the drive of the crystal oscillator which concerns on Embodiment 2 of this invention. The graph showing the relationship between the film thickness h of the temperature compensation film | membrane of the crystal oscillator which concerns on Embodiment 2 of this invention, and the primary frequency temperature variation | change_quantity. Sectional drawing which shows typically the structure and drive of a crystal resonator which concern on Embodiment 3 of this invention. Sectional drawing which shows typically the structure and drive of a crystal oscillator which concern on Embodiment 4 of this invention. Sectional drawing which shows the crystal resonator which concerns on Embodiment 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Crystal oscillator, 20 ... Crystal vibrating piece, 21 ... Base, 30, 40 ... Vibrating arm, 31, 41
... the surface of the quartz crystal vibrating piece, 32, 42 ... the back surface of the quartz crystal vibrating piece, 51-60 ... the electrodes, 71, 72 ...
Piezoelectric thin film, 110, 111... Temperature compensation film.

Claims (4)

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, a temperature compensation layer, and a third electrode 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 first electrode and the second electrode have different polarities, and the first electrode and the third electrode have the same polarity,
The piezoelectric vibrator, wherein the sign of the primary temperature coefficient of the temperature compensation layer and the sign of the primary temperature coefficient of the piezoelectric layer are set in reverse .   The piezoelectric vibrator according to claim 1,
  The temperature compensation layer is formed of a member of any one of Ni-Fe alloy, silicon oxide, teryl oxide, and zirconium oxide.   The piezoelectric vibrator according to claim 1 or 2,
  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 any one of claims 1 to 3 and an amplifier circuit connected to the piezoelectric vibrator.

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