JP2009005023A - Tuning fork vibrator, and oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibrator which is less in property variation due to temperature variation. <P>SOLUTION: The tuning fork vibrator is provided with (a) a plurality of arm sections (11, 13) each of which having a first surface (11a, 13a) arranged so as to be directed in a first direction, and a second surface (11b, 13b) arranged oppositely to the first surface, arranged along a second direction crossing with the first direction, (b) piezoelectric elements (15, 17) disposed on the respective first surfaces of the plurality of arm sections, one by one, (c) a base section connecting respective one ends of the plurality of arm sections, and (d) inorganic films 31, 32 disposed on the respective second surface of the plurality of arm sections. The plurality of arm sections and the base section are made of crystal. Each of the piezoelectric elements is provided with a lower electrode film (15a, 17a) disposed on the first surface, a piezoelectric film (15b, 17b) disposed on the lower electrode film, and an upper electrode film (15c, 17c) disposed on the piezoelectric film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oscillator mainly used as a clock source of an integrated circuit (IC) and an oscillator including the oscillator.

  Japanese Patent Laid-Open No. 2003-227719 (Patent Document 1) discloses a tuning fork made of a non-piezoelectric material having at least two arms and an inner side and an outer side of a center line on the main surface of at least one arm of the tuning fork. First and second electrodes provided to be separated from each other; piezoelectric thin films provided on the first and second electrodes; and third and fourth electrodes provided on the piezoelectric thin films, respectively. , And a thin film micromechanical resonator in which the tuning fork resonates in the X direction by applying AC voltages having opposite phases to the third and fourth electrodes is disclosed. However, the conventional resonator typified by this known example is difficult to suppress the characteristic fluctuation due to the temperature change due to the temperature characteristics of the non-piezoelectric material and the piezoelectric thin film.

JP 2003-227719 A

  An object of some aspects of the present invention is to provide a vibrator with little characteristic fluctuation due to temperature change.

  A tuning fork vibrator according to an aspect of the present invention includes: (a) a first surface that is disposed toward the first direction; and a second surface that is disposed to face the first surface. A plurality of arm portions arranged along a second direction intersecting with one direction; (b) one piezoelectric element provided on the first surface of each of the arm portions; and (c) the above-mentioned A base for connecting one end of the plurality of arms, and (d) an inorganic film provided on the second surface of each of the arms. The arm part and the base part are made of quartz. Each of the piezoelectric elements includes a lower electrode film disposed on the first surface, a piezoelectric film disposed on the lower electrode film, an upper electrode film disposed on the piezoelectric film, including.

  According to the tuning fork vibrator according to the present invention, the temperature characteristic of the piezoelectric film on the first surface side is corrected by the inorganic film provided on the second surface of each arm portion, and vibration with less characteristic fluctuation due to temperature change is achieved. It becomes possible to provide a child. Further, since each arm part and the base part are made of quartz, an effect of suppressing characteristic fluctuation due to temperature change can be obtained.

  Preferably, the inorganic film is a silicon oxide film.

  Thereby, an inorganic film having a high effect of correcting the temperature characteristic can be provided relatively easily.

  Preferably, the crystal is an X-cut plate. An AT cut plate or a Z cut plate may be used.

  By using the X-cut plate, it is possible to further suppress the decrease in temperature characteristics accompanying downsizing and further enhance the effect of improving the temperature characteristics. Further, shape processing by etching of the arm portion and the base portion is facilitated.

As the piezoelectric film described above, for example, a film containing any of ZnO, AlN, PZT, LiNbO _3, or KNbO ₃ can be used.

  It is also preferable to further include an insulating film disposed between the piezoelectric film and the upper electrode film.

  This makes it possible to more reliably insulate between the lower electrode film and the upper electrode film even when a through-hole is formed in a part of the piezoelectric film by making the piezoelectric film thinner. Become.

  An oscillator according to the present invention includes the tuning fork vibrator according to the present invention described above and an inverter connected to the tuning fork vibrator.

  According to the present invention, an oscillator with less characteristic fluctuation due to temperature change is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view of a tuning fork vibrator according to an embodiment. FIG. 2 is a cross-sectional view of the tuning fork vibrator taken along line II-II shown in FIG. The tuning fork vibrator 1 according to the present embodiment shown in FIGS. 1 and 2 includes arm portions 11, 12, and 13, a base portion 14 that connects one end of each of the three arm portions, and piezoelectric elements 15 and 16. , 17 and inorganic films 31, 32, 33.

  The arm part 11 has the 1st surface 11a arrange | positioned toward the 1st direction (Z direction in a figure). Similarly, the arm portion 12 has a first surface 12a arranged in the first direction, and the arm portion 13 has a first surface 13a arranged in the first direction. In the present embodiment, each of the first surfaces 11a, 12a, and 13a is a flat surface, but is not limited thereto, and may be a curved surface, an uneven surface, or the like. These arm portions 11, 12, and 13 are arranged along a second direction (X direction in the drawing) that intersects the first direction. Each arm part 11, 12, and 13 is arrange | positioned so that a longitudinal direction may each follow a 3rd direction (Y direction in a figure). For example, as shown in FIG. 2, the cross-sectional shapes of these arm portions 11, 12, and 13 are rectangular, but are not limited to this shape.

The inorganic film 31 is provided on the back side of the arm portion 11. Similarly, the inorganic film 32 is provided on the back surface side of the arm portion 12, and the inorganic film 33 is provided on the back surface side of the arm portion 13. The inorganic films 31, 32, and 33 are, for example, silicon oxide films (SiO films or SiO ₂ films).

  The base portion 14 is connected to one end (one end portion along the Y direction) of each of the three arm portions 11, 12, and 13, and connects these arm portions 11, 12, and 13. In this embodiment, each arm part 11, 12, 13 and this base part 14 are integrally formed. This is shown in a perspective view in FIG. Each arm part 11, 12, 13 and the base part 14 are formed by shape-processing a quartz plate. The quartz plate is preferably an X-cut plate from the viewpoint of the cut angle, but may be a Z-cut plate (rotation X) or an AT-cut plate. When an X-cut plate is used, the temperature characteristics are good. When a Z-cut plate is used, processing becomes easy.

  The piezoelectric element 15 is provided on the first surface 11 a of the arm portion 11. Similarly, the piezoelectric element 16 is provided on the first surface 12 a of the arm portion 12, and the piezoelectric element 17 is provided on the first surface 13 a of the arm portion 13.

FIG. 4 is an enlarged cross-sectional view showing the structure of the piezoelectric elements 15 and 17. The piezoelectric element 15 includes a lower electrode film 15a disposed on the first surface 11a, a piezoelectric film 15b disposed on the lower electrode film 15a, and an upper electrode film disposed on the piezoelectric film 15b. 15c. In the illustrated example, the piezoelectric film 15b covers the entire lower electrode film 15a. The piezoelectric film 15b is a film containing, for example, any one of ZnO, AlN, PZT, LiNbO ₃ or KNbO ₃ . The film thickness of the piezoelectric film 15b is, for example, about 2 μm.

As shown in FIG. 4, the inorganic film 31 is provided on the second surface 11 b of the arm portion 11. The 2nd surface 11b of the arm part 11 is opposingly arranged with the 1st surface 11a like illustration. That is, one surface of the arm portion 11 is the first surface 11a and the other surface is the second surface 11b. Similarly, the inorganic film 33 is provided on the second surface 13 b of the arm portion 13. The second surface 13b is disposed to face the first surface 13a. That is, one surface of the arm portion 13 is the first surface 13a, and the other surface is the second surface 13b. The inorganic films 31 and 33 are, for example, silicon oxide films (SiO films or SiO ₂ films).

  Here, the film thickness of each of the inorganic films 31 and 33 will be described in detail. The relationship (ratio) between the thickness of the inorganic films 31 and 33 and the thickness of the arm portions 11 and 13 made of quartz is desirably 1: 200 to 1:10. That is, the thickness of the inorganic films 31 and 33 is preferably set to 0.005 to 0.1 times the thickness of the arm portions 11 and 13. As a specific numerical example, when the thickness of the arm portions 11 and 13 is 100 μm, the thickness of the inorganic films 31 and 33 is about 0.5 μm to 10 μm. In addition, the relationship (ratio) between the thickness of the inorganic film 31 and the thickness of the piezoelectric film 15b at this time is desirably 1: 8 to 25: 1. That is, the thickness of the inorganic films 31 and 33 is desirably set to 0.125 to 25 times the thickness of the piezoelectric film 15b. For example, if the film thickness of the inorganic films 31 and 33 is set to 2 μm, the thickness of the piezoelectric films 15b and 17b is about 0.25 μm to 50 μm. Therefore, the film thicknesses of the inorganic films 31 and 33 are appropriately set in a range that satisfies both the relationship with the arm portion and the relationship with the piezoelectric film. The relationship between the inorganic film 32 described later, the arm portion 12, and the piezoelectric film 16b is the same.

  The piezoelectric element 15 shown in FIG. 4 further includes an insulating film 15d. The insulating film 15d is disposed between the piezoelectric film 15b and the upper electrode film 15c. In the illustrated example, the insulating film 15d covers the entire piezoelectric film 15b. The insulating film 15d is, for example, a silicon oxide film. The insulating film 15d functions to protect the piezoelectric film 15b and prevent a short circuit between the lower electrode film 15a and the upper electrode film 15c. The film thickness of the insulating film 15d is desirably 50 nm or more from the viewpoint of preventing a short circuit, and is desirably 500 nm or less from the viewpoint of suppressing deterioration in characteristics of the piezoelectric element 15. Note that the insulating film 15d may be omitted.

The piezoelectric element 17 includes a lower electrode film 17a disposed on the first surface 13a, a piezoelectric film 17b disposed on the lower electrode film 17a, and an upper electrode film disposed on the piezoelectric film 17b. 17c. In the illustrated example, the piezoelectric film 17b covers the entire lower electrode film 17a. The piezoelectric film 17b is a film containing, for example, any one of ZnO, AlN, PZT, LiNbO ₃ or KNbO ₃ . The film thickness of the piezoelectric film 17b is, for example, about 2 μm.

  The illustrated piezoelectric element 17 further includes an insulating film 17d. The insulating film 17d is, for example, a silicon oxide film, and is disposed between the piezoelectric film 17b and the upper electrode film 17c. In the illustrated example, the insulating film 17d covers the entire piezoelectric film 17b. The insulating film 17d is, for example, a silicon oxide film. The insulating film 17d functions to protect the piezoelectric film 17b and to prevent a short circuit between the lower electrode film 17a and the upper electrode film 17c. The film thickness of the insulating film 17d is desirably 50 nm or more from the viewpoint of preventing a short circuit, and is desirably 500 nm or less from the viewpoint of suppressing deterioration in characteristics of the piezoelectric element 17. Note that the insulating film 17d may be omitted.

FIG. 5 is an enlarged cross-sectional view showing the structure of the piezoelectric element 16. The piezoelectric element 16 includes a lower electrode film 16a disposed on the first surface 12a, a piezoelectric film 16b disposed on the lower electrode film 16a, and an upper electrode film disposed on the piezoelectric film 16b. 16c. In the illustrated example, the piezoelectric film 16b covers the entire lower electrode film 16a. The piezoelectric film 16b is a film containing, for example, any one of ZnO, AlN, PZT, LiNbO ₃ or KNbO ₃ . The film thickness of the piezoelectric film 16b is, for example, about 2 μm. The film thickness of the piezoelectric film 16b is desirably set to about 1/40 to 1/4 with respect to the thickness of the arm portion 12. In the present embodiment, the piezoelectric films 15b, 16b, and 17b are integrally formed.

As shown in FIG. 5, the inorganic film 32 is provided on the second surface 12 b of the arm portion 12. The second surface 12b is disposed opposite to the first surface 12a. That is, one surface of the arm portion 12 is the first surface 12a, and the other surface is the second surface 12b. The inorganic film 32 is, for example, a silicon oxide film (SiO film or SiO ₂ film). The film thickness of the inorganic film 32 is set within the same range as the inorganic films 31 and 33 described above.

  The illustrated piezoelectric element 16 further includes an insulating film 16d. The insulating film 16d is, for example, a silicon oxide film, and is disposed between the piezoelectric film 16b and the upper electrode film 16c. In the illustrated example, the insulating film 16d covers the entire piezoelectric film 16b. The insulating film 16d is, for example, a silicon oxide film. The insulating film 16d functions to protect the piezoelectric film 16b and prevent a short circuit between the lower electrode film 16a and the upper electrode film 16c. The film thickness of the insulating film 16d is desirably 50 nm or more from the viewpoint of preventing a short circuit, and is desirably 500 nm or less from the viewpoint of suppressing deterioration in characteristics of the piezoelectric element 16. Note that the insulating film 16d may be omitted.

  The lower electrode films 15a, 16a, and 17a and the upper electrode films 15c, 16c, and 17c are conductor films such as a chromium film and a gold film, respectively. Of these, the lower electrode films 15a and 17a of the piezoelectric elements 15 and 17 provided on the two arm portions 11 and 13 arranged on the outside in the X direction, and one piece arranged on the inside in the X direction. The upper electrode film 16c of the piezoelectric element 16 provided on the arm portion 12 is electrically connected to each other. Further, the upper electrode films 15c and 17c of the piezoelectric elements 15 and 17 provided on the two arm portions 11 and 13 disposed on the outer side in the X direction, and one arm portion disposed on the inner side in the X direction. 12 are electrically connected to the lower electrode film 16a of the piezoelectric element 16 provided on the substrate 12.

The connection structure of each electrode film will be further described mainly with reference to FIGS.
The upper electrode film 15c and the upper electrode film 17c are electrically connected to each other through the connection portion 21c. In the present embodiment, the upper electrode films 15c and 17c and the connection portion 21c are integrally formed. The lower electrode film 16 a is electrically connected to the connection portion 21 c through the connection portion 22 a and the plug (connection piece) 23. Thus, the upper electrode films 15c and 17c and the lower electrode film 16a are electrically connected to each other. Further, the connection portion 21 c is electrically connected to the electrode pad 24. Electrical signals can be supplied to the upper electrode films 15c and 17c and the lower electrode film 16a through the electrode pad 24.

  The lower electrode film 15a and the lower electrode film 17a are electrically connected to each other through the connection portion 21a. In the present embodiment, the lower electrode films 15a and 17a and the connection portion 21a are integrally formed. The upper electrode film 16 c is electrically connected to the connection portion 21 a through a plug (connection piece) 25. Thus, the lower electrode films 15a and 17a and the upper electrode film 16c are electrically connected to each other. Further, the connecting portion 21a is electrically connected to the electrode pad 26. Electric signals can be supplied to the lower electrode films 15a and 17a and the upper electrode film 16c through the electrode pad 26.

  By supplying an electric signal to the electrode pad 24 and the electrode pad 26, the arm portions 11 and 13 and the arm portion 12 can be alternately vibrated up and down. Specifically, when a voltage is applied between each upper electrode film and lower electrode film, the direction of the electric field applied to each of the outer piezoelectric elements 15 and 17 and the direction of the electric field applied to the inner piezoelectric element 16 And reverse. Therefore, as shown by arrows in FIG. 3, the vibration directions of the arm portions 15 and 17 and the vibration direction of the arm portion 16 are opposite to each other, and the arm portions 15 and 17 and the arm portion 16 are alternately moved up and down by electric field application. Do exercise. As described above, by using a tripod structure, the Q value can be increased even in a vibration mode using vertical vibration (vibration along the Z direction in the figure).

  FIG. 6 is a plan view showing another configuration example of the tuning fork vibrator. FIG. 7 is a cross-sectional view of the tuning fork vibrator in the direction of the line VII-VII shown in FIG. In the above-described embodiment, the configuration example of the tuning fork vibrator having three arm portions has been described. However, as shown in FIGS. 6 and 7, the arm portions may be an odd number of five or more. Specifically, the tuning fork vibrator 100 shown in FIGS. 6 and 7 includes five arm portions 111, 112, 113, 114, 115, piezoelectric elements 116, 117, 118, 119, 120, and arms. The base part 121 which connects each one end of each part, and the inorganic film 131, 132, 133, 134, 135 are comprised.

  Each arm part 111, 112, 113, 114, 115 has the 1st surface 111a, 112a, 113a, 114a, 115a each arranged toward the 1st direction (Z direction), and intersects the 1st direction. Are arranged along the second direction (X direction).

  The piezoelectric element 116 is provided on the first surface 111 a of the arm portion 111. Similarly, the piezoelectric element 117 is provided on the first surface 112a of the arm part 112, the piezoelectric element 118 is provided on the first surface 113a of the arm part 113, and the piezoelectric element 119 is provided on the arm part 114. The piezoelectric element 120 is provided on the first surface 115 a of the arm portion 115.

  The base 121 is connected to one end (one end along the Y direction) of each of the five arms 111, 112, 113, 114, 115, and these arms 111, 112, 113, 114 are connected. , 115 are connected. In this embodiment, each arm part 111,112,113,114,115 and this base part 121 are integrally formed. Each arm part 111,112,113,114,115 and the base 121 are formed by shape-processing a quartz plate.

The inorganic film 131 is provided on the back side of the arm portion 111. Similarly, the inorganic film 132 is provided on the back surface side of the arm portion 12, the inorganic film 133 is provided on the back surface side of the arm portion 113, and the inorganic film 134 is provided on the back surface side of the arm portion 114. 135 is provided on the back side of the arm 115. The inorganic films 131 to 135 are, for example, silicon oxide films (SiO films or SiO ₂ films).

  The piezoelectric element 116 includes a lower electrode film 116a disposed on the first surface 111a, a piezoelectric film 116b disposed on the lower electrode 116a, and an upper electrode film 116c disposed on the piezoelectric film 116b. And comprising. Similarly, the piezoelectric element 117 includes a lower electrode film 117a disposed on the first surface 112a, a piezoelectric film 117b disposed on the lower electrode 117a, and an upper section disposed on the piezoelectric film 117b. And an electrode film 117c. The piezoelectric element 118 includes a lower electrode film 118a disposed on the first surface 113a, a piezoelectric film 118b disposed on the lower electrode 118a, and an upper electrode film 118c disposed on the piezoelectric film 118b. And comprising. The piezoelectric element 119 includes a lower electrode film 119a disposed on the first surface 114a, a piezoelectric film 119b disposed on the lower electrode 119a, and an upper electrode film 119c disposed on the piezoelectric film 119b. And comprising. The piezoelectric element 120 includes a lower electrode film 120a disposed on the first surface 115a, a piezoelectric film 120b disposed on the lower electrode 120a, and an upper electrode film 120c disposed on the piezoelectric film 120b. And comprising.

  Of the piezoelectric elements 116 to 120 described above, lower electrode films 116a, 118a, 120a of the piezoelectric elements 116, 118, 120 provided on the odd-numbered arm portions 111, 113, 115, The upper electrode films 112c and 114c of the respective piezoelectric elements provided in the respective arm portions 112 and 114 arranged in the even number are electrically connected to each other. These electrode films are electrically connected to the electrode pads 126. Further, the upper electrode films 116c, 118c, 120c of the piezoelectric elements 116, 118, 120 provided in the arm parts 111, 113, 115 arranged at odd numbers and the arm parts 112 arranged at even numbers. , 114 are electrically connected to lower electrode films 112a, 114a of the respective piezoelectric elements. These electrode films are electrically connected to the electrode pad 124. The specific connection mode is the same as that of the tuning fork type vibrator 1 described above, and the description thereof is omitted here.

  By supplying electric signals to the electrode pad 124 and the electrode pad 126, the arms 111, 113, and 115 (odd-numbered arms) and the arms 112 and 114 (even-numbered arms) are alternately moved up and down. Can be vibrated. As described above, the structure having an odd number of arms can increase the Q value even in a vibration mode using vertical vibration (vibration along the Z direction in the drawing).

  Note that suitable examples of the constituent material, shape, film thickness, and the like of each element of the tuning fork vibrator 100 are the same as those in the above embodiment, and a description thereof will be omitted here.

  FIG. 8 is a graph showing an example of temperature characteristics of the tuning fork vibrator according to the present embodiment. The horizontal axis of the graph shown in FIG. 8 corresponds to temperature (° C.), and the vertical axis corresponds to the frequency temperature characteristic F (ppm). A graph indicated by a thick solid line is a characteristic of the tuning fork vibrator according to the present embodiment. A graph indicated by a dotted line and a graph indicated by a thin solid line are respectively temperature characteristics in a tuning-fork vibrator of a comparative example having no inorganic film. By providing an inorganic film for temperature correction, this tuning fork vibrator can obtain good temperature characteristics in which a parabola having a vertex temperature near 20 ° C. is drawn.

  FIG. 9 is a circuit diagram illustrating a configuration example of an oscillator including the tuning fork vibrator 1 (or the tuning fork vibrator 100). The oscillator shown in FIG. 8 includes a tuning fork vibrator 1 and an inverter 2 connected in parallel with the tuning fork vibrator 1. One end of the inverter 2 is connected to the electrode pad 24 and the other end is connected to the electrode pad 26. Further, as shown in the figure, a capacitive element (capacitor) 3 connected between one connection point between the tuning fork vibrator 1 and the inverter 2 and the ground terminal, and the other of the tuning fork vibrator 1 and the inverter 2. And a capacitive element (capacitor) 4 connected between the connection point and the ground terminal.

  According to the present embodiment described above, the temperature characteristics of the piezoelectric film and the like on the first surface side are corrected by the inorganic film provided on the second surface of each arm portion, and the tuning fork type in which the characteristic variation due to the temperature change is small. A vibrator can be provided. Further, since each arm part and the base part are made of quartz, an effect of suppressing characteristic fluctuation due to temperature change can be obtained. Further, by providing the inorganic film on the second surface of each arm part, an effect of relieving the stress generated in the piezoelectric film on the first surface side can be obtained. Further, according to the present embodiment, it is possible to provide an oscillator with little characteristic change due to temperature change.

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously. For example, in the above-described embodiment, a tuning fork vibrator having an odd number of arm portions is illustrated, but the number of arm portions is not necessarily an odd number, and may be at least two or more. . Further, in the case of having an odd number of arm portions, in addition to the case of having the three or five arm portions described above, a tuning fork having a larger number of odd number (7, 9,...) Arm portions. It is also possible to configure a type resonator. Further, in the above-described embodiment, the quartz is exemplified as the constituent material of the arm portions and the base portion connecting them, but other piezoelectric materials can also be used.

It is a top view of the tuning fork type vibrator of one embodiment. It is sectional drawing in the II-II line | wire shown in FIG. 1 of a tuning fork type vibrator. It is a perspective view which shows an arm part and a base. It is the expanded sectional view which showed the structure of the piezoelectric element. It is the expanded sectional view which showed the structure of the piezoelectric element. It is sectional drawing of the VII-VII line direction shown in FIG. 6 of this tuning fork type vibrator. It is a top view which shows the other structural example of a tuning fork type vibrator. It is a graph which shows an example of the temperature characteristic of a tuning fork type vibrator. It is a circuit diagram which shows the structural example of an oscillator.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tuning fork type vibrator, 2 ... Inverter, 3, 4 ... Capacitance element, 11, 12, 13 ... Arm part, 11a, 12a, 13a ... First surface, 14 ... Base part, 15, 16, 17 ... Piezoelectric element 15a, 16a, 17a ... lower electrode film, 15b, 16b, 17b ... piezoelectric film, 15c, 16c, 17c ... upper electrode film, 15d, 16d, 17d ... insulating film, 21a, 21c, 22a ... connection part, 24 , 26 ... electrode pads, 31, 32, 33 ... inorganic films

Claims (6)

Each having a first surface arranged in the first direction and a second surface arranged to face the first surface, and arranged in a second direction intersecting the first direction Arms,
One piezoelectric element provided on the first surface of each of the arm parts;
A base connecting one end of the arm,
An inorganic film provided on the second surface of each of the arms;
Including
The arm portion and the base portion are made of quartz,
Each of the piezoelectric elements includes a lower electrode film disposed on the first surface, a piezoelectric film disposed on the lower electrode film, an upper electrode film disposed on the piezoelectric film, including,
Tuning fork type vibrator. The inorganic film is a silicon oxide film;
The tuning fork vibrator according to claim 1. The crystal is an X-cut plate;
The tuning fork vibrator according to claim 1 or 2. The piezoelectric film is a film containing any of ZnO, AlN, PZT, LiNbO ₃ or KNbO ₃ .
The tuning fork vibrator according to any one of claims 1 to 3. An insulating film disposed between the piezoelectric film and the upper electrode film;
The tuning fork vibrator according to any one of claims 1 to 4, further comprising: A tuning fork vibrator according to any one of claims 1 to 5,
An inverter connected to the tuning fork vibrator,
Including an oscillator.

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