Piezoelectric vibration device

Abstract

To provide a piezoelectric vibration device that can contribute to miniaturization of a circuit board.SOLUTION: A piezoelectric vibration device includes: a crystal vibration plate 10 having a first excitation electrode 111 and a second excitation electrode 112 paired with the first excitation electrode 111; and a first sealing member 20 and a second sealing member 30 covering both main surfaces of the crystal vibration plate 10. The piezoelectric vibrating device includes: a first capacitor 501 electrically connected to the first excitation electrode 111, by tightly sealing a vibration part 11 containing the first excitation electrode 111 and the second excitation electrode 112 by bonding the first sealing member 20 with the crystal vibration plate 10, and bonding the second sealing member 30 with the crystal vibration plate 10; and a second capacitor 601 electrically connected to the second excitation electrode 112. The first capacitor 501 is provided on the main surface of the first sealing member 20 or the second sealing member 30, and the second capacitor 601 is provided on the main surface of the first sealing member 20 or the second sealing member 30 as the crystal resonator 100.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a piezoelectric vibration device such as a piezoelectric vibrator.

Background Art

[0002] In recent years, the operating frequencies of various electronic devices have been increasing, and the packages have been miniaturized (especially made thinner). Therefore, with the increase in frequency and miniaturization of the package, piezoelectric vibration devices (such as crystal resonators and crystal oscillators) are also required to cope with the increase in frequency and miniaturization of the package.

[0003] In this type of piezoelectric vibration device, its housing is composed of a package having a substantially rectangular parallelepiped shape. As such a configuration, for example, it is composed of a first sealing member and a second sealing member made of glass or crystal, and a piezoelectric vibration plate made of crystal with exciting electrodes formed on both main surfaces. The first sealing member and the second sealing member are laminated and joined via the piezoelectric vibration plate, and the vibration portion (exciting electrode) of the piezoelectric vibration plate arranged inside the package (internal space) is hermetically sealed. The configuration of a piezoelectric vibrator is disclosed (see Patent Document 1). Hereinafter, such a laminated form of the piezoelectric vibration device is referred to as a sandwich structure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when generally attempting to mount a piezoelectric vibrator as a piezoelectric vibration device on a circuit board, it is necessary to form an oscillation circuit as shown in FIG. 16. Such an oscillation circuit is composed of, for example, a piezoelectric vibrator 1, a feedback resistor 2, an inverter 3, an input-side capacitor 4, and an output-side capacitor 5. The oscillation circuit has a pattern in which each component is composed of discrete (individual) components and a pattern in which each component is monolithically integrated (integrated) into an integrated circuit (IC). However, each capacitor constituting the oscillation circuit requires an electrode area of a certain size in the mounting area. Therefore, when attempting to mount each capacitor individually on the circuit board, it will impede the miniaturization of the circuit board. Also, when attempting to monolithically integrate each capacitor into an IC, the miniaturization of the IC will be impeded, and as a result, the miniaturization of the circuit board will be impeded. That is, when attempting to mount a piezoelectric vibrator having a sandwich structure as in Patent Document 1 on a circuit board to form an oscillation circuit, there is a problem that it is necessary to separately mount two capacitors on an IC or the circuit board, which impedes the miniaturization of the circuit board.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a piezoelectric vibration device that can contribute to the miniaturization of a circuit board.

Means for Solving the Problems

[0007] The present invention relates to a piezoelectric vibration device including a piezoelectric diaphragm having a first excitation electrode formed on a main surface of a substrate and a second excitation electrode formed on the main surface of the substrate and paired with the first excitation electrode, and a first sealing member and a second sealing member covering both main surfaces of the piezoelectric diaphragm. The first sealing member is joined to the piezoelectric diaphragm, and the second sealing member is joined to the piezoelectric diaphragm, thereby providing an internal space in which a vibration portion of the piezoelectric diaphragm including the first excitation electrode and the second excitation electrode is hermetically sealed. In the piezoelectric vibration device, a first capacitor electrically connected to the first excitation electrode and a second capacitor electrically connected to the second excitation electrode are provided. The first capacitor is provided on a main surface of the first sealing member or the second sealing member, and the second capacitor is provided on a main surface of the first sealing member or the second sealing member.

[0008] That is, the piezoelectric vibration device of the present invention includes a first capacitor electrically connected to the first excitation electrode and a second capacitor electrically connected to the second excitation electrode. The first capacitor is provided on a main surface of the first sealing member or the second sealing member, and the second capacitor is provided on a main surface of the first sealing member or the second sealing member. With such a configuration, when attempting to mount the piezoelectric vibration device on a circuit board, it is not necessary to separately mount the two capacitors required for the oscillation circuit on the circuit board, and the occupied area of the circuit board for the piezoelectric vibration device can be reduced. That is, it can contribute to the miniaturization of the circuit board. Further, the characteristics of the two capacitors constituting the oscillation circuit are generally determined by the characteristics of the connected crystal oscillator. With the configuration as in the present invention, a piezoelectric vibration device with capacitors corresponding to the characteristics of the crystal oscillator can be provided in advance. When the piezoelectric vibration device of the present invention is mounted on a circuit board to form an oscillation circuit, the burden of characteristic adjustment can be reduced.

[0009] Further, the first capacitor and the second capacitor may be arranged in the internal space of the piezoelectric vibration device and provided on the main surface facing the piezoelectric vibration plate of the first sealing member or the second sealing member. With such a configuration, the first capacitor and the second capacitor can be arranged in a hermetically sealed internal space, and it is possible to prevent a change in capacitance over time due to moisture absorption or the like.

[0010] Further, the first capacitor and the second capacitor may each include a dielectric film, a lower electrode film, and an upper electrode film, and may have a stacked structure in which the dielectric film is sandwiched between the lower electrode film and the upper electrode film. With such a configuration, the first capacitor and the second capacitor can be mounted in the form of extremely thin films, and it is possible to achieve a reduction in the height of the piezoelectric vibration device.

[0011] Also, in a plan view, the area of the upper electrode film may be smaller than the areas of the lower electrode film and the dielectric film. With such a configuration, when the upper electrode film is formed by vapor deposition by sputtering, photolithography, or the like, even if the formation position is slightly deviated, there will be no short circuit or change in capacitance, and a piezoelectric vibration device with stable characteristics can be obtained.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a piezoelectric vibration device that can contribute to the miniaturization of a circuit board.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a case where the piezoelectric vibration device to which the present invention is applied is a crystal oscillator will be described.

[0015] First, the basic structure of the crystal oscillator 100 according to this embodiment (the first embodiment) will be described. As shown in FIG. 1, the crystal oscillator 100 includes a crystal vibrating plate (piezoelectric vibrating plate) 10, a first sealing member 20, and a second sealing member 30. In this crystal oscillator 100, the crystal vibrating plate 10 and the first sealing member 20 are joined at a sealing portion (seal path) 115, and the crystal vibrating plate 10 and the second sealing member 30 are joined at a sealing portion (seal path) 116, thereby forming a package having a substantially rectangular parallelepiped sandwich structure. That is, in the crystal oscillator 100, the first sealing member 20 and the second sealing member 30 are joined to each of the main surfaces of the crystal vibrating plate 10, so that an internal space (cavity) of the package is formed, and a vibrating portion 11 (see FIGS. 4 and 5) is hermetically sealed in this internal space.

[0016] Next, each of the members of the crystal vibrating plate 10, the first sealing member 20, and the second sealing member 30 in the above-described crystal oscillator 100 will be described with reference to FIGS. 1 to 7. Here, each member configured as a single unit that is not joined will be described. FIGS. 2 to 7 merely show one configuration example of each of the crystal vibrating plate 10, the first sealing member 20, and the second sealing member 30, and these do not limit the present invention.

[0017] As shown in FIGS. 4 and 5, the crystal diaphragm 10 is a substrate made of crystal, and both of its main surfaces (the first main surface 101 and the second main surface 102) are formed as flat and smooth surfaces (mirror-finished surfaces). In the present embodiment, an AT-cut crystal plate that performs thickness-shear vibration is used as the crystal diaphragm 10. In the crystal diaphragm 10 shown in FIGS. 4 and 5, both main surfaces 101 and 102 of the crystal diaphragm 10 are the XZ' planes. In this XZ' plane, the direction parallel to the short side direction (the short-side direction) of the crystal diaphragm 10 is defined as the X-axis direction, and the direction parallel to the long side direction (the long-side direction) of the crystal diaphragm 10 is defined as the Z'-axis direction. Note that the AT-cut is a processing method of cutting out at an angle inclined by 35° 15' around the X-axis with respect to the Z-axis among the three crystal axes of synthetic quartz, namely, the electrical axis (X-axis), the mechanical axis (Y-axis), and the optical axis (Z-axis). In the AT-cut crystal plate, the X-axis coincides with the crystal axis of the crystal. The Y'-axis and the Z'-axis coincide with the axes inclined by approximately 35° 15' from the Y-axis and the Z-axis of the crystal axis of the crystal, respectively (this cutting angle may be slightly changed within the range of adjusting the frequency-temperature characteristics of the AT-cut crystal diaphragm). The Y'-axis direction and the Z'-axis direction correspond to the cutting directions when cutting out the AT-cut crystal plate.

[0018] The crystal diaphragm 10 has a vibration portion 11 formed in a substantially rectangular shape, an outer frame portion 12 surrounding the outer periphery of the vibration portion 11, and a holding portion 13 that holds the vibration portion 11 by connecting the vibration portion 11 and the outer frame portion 12. That is, the crystal diaphragm 10 has a configuration in which the vibration portion 11, the outer frame portion 12, and the holding portion 13 are integrally provided. The holding portion 13 extends (projects) from only one corner portion located in the +X direction and -Z'-direction of the vibration portion 11 toward the outer frame portion 12 in the -Z'-direction. And a cutout portion 10a formed by cutting out the crystal diaphragm 10 is provided between the vibration portion 11 and the outer frame portion 12. In the present embodiment, only one holding portion 13 that connects the vibration portion 11 and the outer frame portion 12 is provided on the crystal diaphragm 10, and the cutout portion 10a is continuously formed so as to surround the outer periphery of the vibration portion 11.

[0019] On both main surfaces 101 and 102 of the crystal vibrating plate 10, a pair of exciting electrodes (the first exciting electrode 111 and the second exciting electrode 112) are formed. The first exciting electrode 111 is provided on the first main surface 101 side of the vibrating portion 11, and the second exciting electrode 112 is provided on the second main surface 102 side of the vibrating portion 11. Lead wirings (the first lead wiring 113 and the second lead wiring 114) for connecting these exciting electrodes to external electrode terminals are connected to the first exciting electrode 111 and the second exciting electrode 112. The first lead wiring 113 is drawn out from the first exciting electrode 111, passes through the holding portion 13, and is connected to a connection bonding pattern 14 formed on the outer frame portion 12. The second lead wiring 114 is drawn out from the second exciting electrode 112, passes through the holding portion 13, and is connected to a connection bonding pattern 15 formed on the outer frame portion 12.

[0020] On both main surfaces (the first main surface 101 and the second main surface 102) of the crystal vibrating plate 10, vibration plate side sealing portions for bonding the crystal vibrating plate 10 to the first sealing member 20 and the second sealing member 30 are respectively provided. As the vibration plate side sealing portion of the first main surface 101, a vibration plate side first bonding pattern 121 is formed, and as the vibration plate side sealing portion of the second main surface 102, a vibration plate side second bonding pattern 122 is formed. The vibration plate side first bonding pattern 121 and the vibration plate side second bonding pattern 122 are provided on the outer frame portion 12 and are formed in an annular shape in plan view. The outer peripheral edge of the vibration plate side first bonding pattern 121 is provided close to the outer peripheral edge of the first main surface 101 of the crystal vibrating plate 10 (outer frame portion 12). The outer peripheral edge of the vibration plate side second bonding pattern 122 is provided close to the outer peripheral edge of the second main surface 102 of the crystal vibrating plate 10 (outer frame portion 12).

[0021] On the first main surface 101 of the crystal vibrating plate 10, interlayer wiring bonding patterns 181 and 182 are formed on the outer peripheral side of the diaphragm-side first bonding pattern 121. The interlayer wiring bonding patterns 181 and 182 are not connected to the diaphragm-side first bonding pattern 121 and are provided at a predetermined interval from the diaphragm-side first bonding pattern 121. The interlayer wiring bonding pattern 181 is provided in a portion of the first main surface 101 of the crystal vibrating plate 10 on the -X direction side and the +Z' direction side, and is connected to a first side surface wiring 171 described later. The interlayer wiring bonding pattern 182 is provided in a portion of the first main surface 101 of the crystal vibrating plate 10 on the +X direction side and the -Z' direction side, and is connected to a second side surface wiring 172 described later.

[0022] Also, on the second main surface 102 of the crystal vibrating plate 10, interlayer wiring bonding patterns 183 and 184 are formed on the outer peripheral side of the diaphragm-side second bonding pattern 122. The interlayer wiring bonding patterns 183 and 184 are not connected to the diaphragm-side second bonding pattern 122 and are provided at a predetermined interval from the diaphragm-side second bonding pattern 122. The interlayer wiring bonding pattern 183 is provided in a portion of the second main surface 102 of the crystal vibrating plate 10 on the -X direction side and the +Z' direction side, and is connected to the first side surface wiring 171 described later. The interlayer wiring bonding pattern 184 is provided in a portion of the second main surface 102 of the crystal vibrating plate 10 on the +X direction side and the -Z' direction side, and is connected to the second side surface wiring 172 described later.

[0023] As shown in FIGS. 4 and 5, one through hole penetrating between the first main surface 101 and the second main surface 102 is formed in the crystal vibrating plate 10. Specifically, the first through hole 162 is an outer frame portion 12 and is provided on the inner peripheral side of the diaphragm-side first bonding pattern 121 and the diaphragm-side second bonding pattern 122. Further, the first through hole 162 is provided on one side in the Z' axis direction of the vibrating portion 11 (in FIGS. 4 and 5, the -Z' direction side). Around the first through hole 162, a connection bonding pattern 124 is formed on the first main surface 101 side, and a connection bonding pattern 15 is formed on the second main surface 102 side.

[0024] In the first through-hole 162, a through electrode for achieving electrical connection between the electrodes formed on the first main surface 101 and the second main surface 102 is formed along the inner wall surface of the first through-hole 162. Also, the central portion of the first through-hole 162 becomes a hollow through portion that penetrates between the first main surface 101 and the second main surface 102. Note that the electrical connection between the electrodes on the first main surface 101 and the second main surface 102 may be achieved by means other than the through electrodes of the through-holes (for example, wiring formed on the inner wall surface of the outer frame portion 12 or the like).

[0025] As shown in FIGS. 4 and 5, two side wirings are formed on the side surface of the crystal vibrating plate 10. Specifically, a first side wiring 171 is formed on the side surface 103 on the -X direction side of the crystal vibrating plate 10. A second side wiring 172 is formed on the side surface 104 on the +X direction side of the crystal vibrating plate 10.

[0026] The first side wiring 171 is formed on the portion on the +Z' direction side of the side surface 103 on the -X direction side of the crystal vibrating plate 10. The first side wiring 171 is connected to the interlayer wiring bonding pattern 181 provided on the first main surface 101 of the crystal vibrating plate 10. The first side wiring 171 is connected to the interlayer wiring bonding pattern 183 provided on the second main surface 202 of the crystal vibrating plate 10.

[0027] The second side wiring 172 is formed on the portion on the -Z' direction side of the side surface 104 on the +X direction side of the crystal vibrating plate 10. The second side wiring 172 is connected to the interlayer wiring bonding pattern 182 provided on the first main surface 101 of the crystal vibrating plate 10. The second side wiring 172 is connected to the interlayer wiring bonding pattern 184 provided on the second main surface 202 of the crystal vibrating plate 10.

[0028] Also, as shown in FIGS. 4 and 5, two internal wirings are formed on the inner wall surface of the outer frame portion 12 of the crystal vibrating plate 10. Specifically, a first internal wiring 173 is formed on the inner wall surface 105 on the -X direction side of the outer frame portion 12 of the crystal vibrating plate 10. A second internal wiring 174 is formed on the inner wall surface 106 on the +X direction side of the outer frame portion 12 of the crystal vibrating plate 10.

[0029] The first internal wiring 173 is provided with a predetermined width at the center of the inner wall surface 105 on the -X direction side of the outer frame portion 12. The first internal wiring 173 is connected to the diaphragm-side first bonding pattern 121 provided on the first main surface 101 of the crystal diaphragm 10. The first internal wiring 173 is connected to the diaphragm-side second bonding pattern 122 provided on the second main surface 102 of the crystal diaphragm 10.

[0030] The second internal wiring 174 is provided with a predetermined width at the center of the inner wall surface 106 on the +X direction side of the outer frame portion 12. The second internal wiring 174 is connected to the diaphragm-side first bonding pattern 121 provided on the first main surface 101 of the crystal diaphragm 10. The second internal wiring 174 is connected to the diaphragm-side second bonding pattern 122 provided on the second main surface 102 of the crystal diaphragm 10. The first internal wiring 173 and the second internal wiring 174 are arranged to face each other with the vibrating portion 11 interposed therebetween.

[0031] As shown in FIGS. 2 and 3, the first sealing member 20 is a rectangular parallelepiped substrate formed from a single AT-cut crystal plate. The second main surface 202 (the surface to be joined to the crystal diaphragm 10) of the first sealing member 20 is formed as a flat and smooth surface (mirror finish). Although the first sealing member 20 does not have a vibrating portion, by using an AT-cut crystal plate similar to the crystal diaphragm 10, the thermal expansion coefficients of the crystal diaphragm 10 and the first sealing member 20 can be made the same, and thermal deformation in the crystal unit 100 can be suppressed. Also, the directions of the X-axis, Y-axis, and Z'-axis in the first sealing member 20 are the same as those in the crystal diaphragm 10.

[0032] On the first main surface 201 of the first sealing member 20 (the outer main surface not facing the crystal vibrating plate 10), as shown in FIG. 2, first and second terminals 22 and 23 for wiring and a metal film 28 for shielding (for ground connection) are formed. The first and second terminals 22 and 23 for wiring are provided as wirings for electrically connecting the first and second excitation electrodes 111 and 112 of the crystal vibrating plate 10 and the external electrode terminals 32 of the second sealing member 30. The first and second terminals 22 and 23 are provided at both ends in the Z' axis direction, the first terminal 22 is provided on the +Z' direction side, and the second terminal 23 is provided on the -Z' direction side. The first and second terminals 22 and 23 are formed to extend in the X axis direction. The first terminal 22 and the second terminal 23 are formed in a substantially rectangular shape. The first terminal 22 extends to the end on the -X direction side of the first main surface 201 and is connected to a third side surface wiring 271 described later. The second terminal 23 extends to the end on the +X direction side of the first main surface 201 and is connected to a fourth side surface wiring 272 described later.

[0033] The metal film 28 is provided between the first and second terminals 22 and 23 and is arranged at a predetermined interval from the first and second terminals 22 and 23. The metal film 28 is provided in almost all regions of the region where the first and second terminals 22 and 23 are not formed on the first main surface 201 of the first sealing member 20. The metal film 28 is provided from the end on the +X direction side to the end on the -X direction side of the first main surface 201 of the first sealing member 20. The metal film 28 extends to the end on the -X direction side of the first main surface 201 and is connected to a fifth side surface wiring 273 described later. Also, the metal film 28 extends to the end on the +X direction side of the first main surface 201 and is connected to a sixth side surface wiring 274 described later.

[0034] In the first sealing member 20, as shown in FIGS. 2 and 3, four through holes penetrating between the first main surface 201 and the second main surface 202 are formed. Specifically, second, third, fourth, and fifth through holes 212, 213, 214, and 215 are provided in the +Z' direction and the -Z' direction of FIGS. 2 and 3, respectively.

[0035] In the second, third, fourth, and fifth through-holes 212, 213, 214, and 215, through electrodes for establishing electrical connection between the electrodes formed on the first main surface 201 and the second main surface 202 are formed along the inner wall surfaces of the second, third, fourth, and fifth through-holes 212, 213, 214, and 215, respectively. Also, the central portions of the second, third, fourth, and fifth through-holes 212, 213, 214, and 215 are through portions in a hollow state that penetrate between the first main surface 201 and the second main surface 202. And the through electrode of the second through-hole 212 is electrically connected to the first terminal 22. The through electrode of the third through-hole 213 is electrically connected to the second terminal 23. The through electrodes of the fourth and fifth through-holes 214 and 215 are electrically connected to the metal film 28.

[0036] On the second main surface 202 of the first sealing member 20, a sealing member side first bonding pattern 24 as a first sealing portion on the sealing member side for bonding to the crystal vibrating plate 10 is formed. The sealing member side first bonding pattern 24 is formed in an annular shape in plan view. The outer peripheral edge of the sealing member side first bonding pattern 24 is provided close to the outer peripheral edge of the second main surface 202 of the first sealing member 20. Also, on the second main surface 202 of the first sealing member 20, a connection bonding pattern 261 is formed around the second through-hole 212, and a connection bonding pattern 262 is formed around the third through-hole 213. Further, a connection bonding pattern 263 is formed on the opposite side (-Z' direction side) of the long axis direction of the first sealing member 20 with respect to the connection bonding pattern 261, and the connection bonding pattern 261 and the connection bonding pattern 263 are connected by a wiring pattern 27.

[0037] Also, a first capacitor 501 and a second capacitor 601 are provided on the second main surface 202 of the first sealing member 20. The first capacitor 501 is connected to the wiring pattern 27 by a first capacitor connection electrode 502 and is connected to the fourth through-hole 214 by a first capacitor connection electrode 503. Also, the second capacitor 601 is connected to the connection bonding pattern 262 by a second capacitor connection electrode 602 and is connected to the fifth through-hole 215 by a second capacitor connection electrode 603.

[0038] FIG. 8 is an enlarged view of the vicinity of the first and second capacitors 501 and 601 in FIG. 3, and FIG. 9 is a cross-sectional view taken along line A-A of the first and second capacitors 501 and 601 in FIG. 8. The first capacitor 501 is composed of an upper electrode film 504, a lower electrode film 505, and a dielectric film 506. The first capacitor 501 is a thin-film capacitor in which the lower electrode film 505, the dielectric film 506, and the upper electrode film 504 are laminated in this order.

[0039] The lower electrode film 505 is formed in a substantially rectangular shape in the present embodiment, and one end thereof is connected to the first capacitor connection electrode 503. The dielectric film 506 is a thin film formed of an insulating material, and is formed in a substantially rectangular shape in the present embodiment. As the insulating material for forming the dielectric film 506, for example, silicon dioxide or titanium oxide can be used. Further, the dielectric film 506 is disposed so as to overlap the lower electrode film 505 and protrude toward the first capacitor connection electrode 502 side.

[0040] The upper electrode film 504 is disposed so as to overlap the dielectric film 506, and is formed to have a smaller area than the lower electrode film 505 and the dielectric film 506. The upper electrode film 504 in the present embodiment has a central electrode 504a formed in a circular shape and an upper connection electrode 504b connecting the central electrode 504a and the first capacitor connection electrode 502.

[0041] The second capacitor 601 is composed of an upper electrode film 604, a lower electrode film 605, and a dielectric film 606. The second capacitor 601 is a thin-film capacitor in which the lower electrode film 605, the dielectric film 606, and the upper electrode film 604 are laminated in this order.

[0042] The lower electrode film 605 is formed in a substantially rectangular shape in the present embodiment, and one end thereof is connected to the second capacitor connection electrode 603. The dielectric film 606 is a thin film formed of an insulating material, and is formed in a substantially rectangular shape in this embodiment. As the insulating material for forming the dielectric film 606, for example, silicon dioxide or titanium oxide can be used. Further, the dielectric film 606 is disposed so as to overlap the lower electrode film 605 and protrude toward the second capacitor connection electrode 602 side.

[0043] The upper electrode film 604 is disposed so as to overlap the dielectric film 606, and is formed to have a smaller area than the lower electrode film 605 and the dielectric film 606. The upper electrode film 604 in this embodiment has a central electrode 604a formed in a circular shape and an upper connection electrode 604b that connects the central electrode 604a and the second capacitor connection electrode 602.

[0044] The characteristics such as the capacitance of the first and second capacitors 501 and 601 are determined by the areas, thicknesses, shapes, etc. of the upper electrode films 504 and 604, the lower electrode films 505 and 605, and the dielectric films 506 and 606 that constitute them. The characteristics of the first and second capacitors 501 and 601 are determined by the characteristics of the crystal oscillator 100. Therefore, the areas, thicknesses, and shapes of the upper electrode films 504 and 604, the lower electrode films 505 and 605, and the dielectric films 506 and 606 are appropriately changed according to the characteristics of the crystal oscillator 100.

[0045] Further, on the second main surface 202 of the first sealing member 20, interlayer wiring bonding patterns 281 and 282 are formed on the outer peripheral side of the sealing member side first bonding pattern 24. The interlayer wiring bonding patterns 281 and 282 are not connected to the sealing member side first bonding pattern 24, and are provided at a predetermined interval from the sealing member side first bonding pattern 24. The interlayer wiring bonding pattern 281 is provided in a portion on the -X direction side and +Z' direction side of the second main surface 202 of the first sealing member 20, and is connected to the third side surface wiring 271 described later. The interlayer wiring bonding pattern 282 is provided in a portion on the +X direction side and -Z' direction side of the second main surface 202 of the first sealing member 20, and is connected to the fourth side surface wiring 272 described later.

[0046] On the side surface of the first sealing member 20, as shown in FIGS. 2 and 3, four side surface wirings are formed. Specifically, on the side surface 203 of the first sealing member 20 on the -X direction side, the third side surface wiring 271 and the fifth side surface wiring 273 are formed. On the side surface 204 of the first sealing member 20 on the +X direction side, the fourth side surface wiring 272 and the sixth side surface wiring 274 are formed.

[0047] The third side surface wiring 271 is formed on the portion on the +Z' direction side of the side surface 203 of the first sealing member 20 on the -X direction side. The third side surface wiring 271 is connected to the first terminal 22 provided on the first main surface 201 of the first sealing member 20. The third side surface wiring 271 is connected to the interlayer wiring bonding pattern 281 provided on the second main surface 202 of the first sealing member 20.

[0048] The fourth side surface wiring 272 is formed on the portion on the -Z' direction side of the side surface 204 of the first sealing member 20 on the +X direction side. The fourth side surface wiring 272 is connected to the second terminal 23 provided on the first main surface 201 of the first sealing member 20. The fourth side surface wiring 272 is connected to the interlayer wiring bonding pattern 282 provided on the second main surface 202 of the first sealing member 20.

[0049] The fifth side surface wiring 273 is formed on the portion on the -Z' direction side of the side surface 203 of the first sealing member 20 on the -X direction side. The fifth side surface wiring 273 is connected to the metal film 28 provided on the first main surface 201 of the first sealing member 20. The fifth side surface wiring 273 is connected to the first bonding pattern 24 on the sealing member side provided on the second main surface 202 of the first sealing member 20.

[0050] The sixth side surface wiring 274 is formed on the portion on the +Z' direction side of the side surface 204 of the first sealing member 20 on the +X direction side. The sixth side surface wiring 274 is connected to the metal film 28 provided on the first main surface 201 of the first sealing member 20. The sixth side surface wiring 274 is connected to the first bonding pattern 24 on the sealing member side provided on the second main surface 202 of the first sealing member 20.

[0051] As shown in FIGS. 6 and 7, the second sealing member 30 is a rectangular parallelepiped substrate formed from a single AT-cut crystal plate. The first main surface 301 (the surface to be joined to the crystal vibrator 10) of the second sealing member 30 is formed as a flat and smooth surface (mirror finish). In the second sealing member 30 as well, it is desirable to use an AT-cut crystal plate in the same manner as the crystal vibrator 10 and to set the directions of the X-axis, Y-axis, and Z'-axis to be the same as those of the crystal vibrator 10.

[0052] On the first main surface 301 of the second sealing member 30, a second joining pattern 31 on the sealing member side, which serves as a second sealing portion for joining to the crystal vibrator 10, is formed. The second joining pattern 31 on the sealing member side is formed in an annular shape in a plan view. The outer peripheral edge of the second joining pattern 31 on the sealing member side is provided close to the outer peripheral edge of the first main surface 301 of the second sealing member 30.

[0053] Also, on the first main surface 301 of the second sealing member 30, interlayer wiring joining patterns 381 and 382 are formed on the outer peripheral side of the second joining pattern 31 on the sealing member side. The interlayer wiring joining patterns 381 and 382 are not connected to the second joining pattern 31 on the sealing member side and are provided at a predetermined interval from the second joining pattern 31 on the sealing member side. The interlayer wiring joining pattern 381 is provided in a portion on the -X direction side and +Z'-direction side of the first main surface 301 of the second sealing member 30 and is connected to a seventh side surface wiring 371 described later. The interlayer wiring joining pattern 382 is provided in a portion on the +X direction side and -Z'-direction side of the first main surface 301 of the second sealing member 30 and is connected to an eighth side surface wiring 372 described later.

[0054] On the second main surface 302 of the second sealing member 30 (the outer main surface not facing the crystal vibrating plate 10), four external electrode terminals 32 for electrically connecting to an external circuit board provided outside the crystal unit 100 are provided. The external electrode terminals 32 are respectively located at the four corners (corner portions) of the second main surface 302 of the second sealing member 30. The external electrode terminals 32 are respectively provided along the internal space of the package of the crystal unit 100 in a plan view and are formed in a substantially L shape. The external electrode terminals 32 are provided at positions overlapping with the outer frame portion 12 of the crystal vibrating plate 10 described above in a plan view.

[0055] On the side surface of the second sealing member 30, as shown in FIGS. 6 and 7, four side surface wirings are formed. Specifically, on the side surface 303 on the -X direction side of the second sealing member 30, a seventh side surface wiring 371 and a ninth side surface wiring 373 are formed. On the side surface 304 on the +X direction side of the second sealing member 30, an eighth side surface wiring 372 and a tenth side surface wiring 374 are formed.

[0056] The seventh side surface wiring 371 is formed in a portion on the +Z' direction side of the side surface 303 on the -X direction side of the second sealing member 30. The seventh side surface wiring 371 is connected to an interlayer wiring bonding pattern 381 provided on the first main surface 301 of the second sealing member 30. The seventh side surface wiring 371 is connected to an external electrode terminal 32 provided on the second main surface 302 of the second sealing member 30.

[0057] The eighth side surface wiring 372 is formed in a portion on the -Z' direction side of the side surface 304 on the +X direction side of the second sealing member 30. The eighth side surface wiring 372 is connected to an interlayer wiring bonding pattern 382 provided on the first main surface 301 of the second sealing member 30. The eighth side surface wiring 372 is connected to an external electrode terminal 32 provided on the second main surface 302 of the second sealing member 30.

[0058] The ninth side wiring 373 is formed in a portion on the -Z' direction side of the side surface 303 on the -X direction side of the second sealing member 30. The ninth side wiring 373 is connected to the sealing member side second bonding pattern 31 provided on the first main surface 301 of the second sealing member 30. The ninth side wiring 373 is connected to the external electrode terminal 32 provided on the second main surface 302 of the second sealing member 30.

[0059] The tenth side wiring 374 is formed in a portion on the +Z' direction side of the side surface 304 on the +X direction side of the second sealing member 30. The tenth side wiring 374 is connected to the sealing member side second bonding pattern 31 provided on the first main surface 301 of the second sealing member 30. The tenth side wiring 374 is connected to the external electrode terminal 32 provided on the second main surface 302 of the second sealing member 30.

[0060] In the crystal oscillator 100 including the crystal resonator 10, the first sealing member 20, and the second sealing member 30 configured as described above, the crystal resonator 10 and the first sealing member 20 are diffusion bonded in a state where the diaphragm side first bonding pattern 121 and the sealing member side first bonding pattern 24 are overlapped, and the crystal resonator 10 and the second sealing member 30 are diffusion bonded in a state where the diaphragm side second bonding pattern 122 and the sealing member side second bonding pattern 31 are overlapped, thereby manufacturing the package having the sandwich structure shown in FIGS. 1, 8, and 9. As a result, the first main surface 101 of the crystal resonator 10 is covered by the first sealing member 20, and further, the second main surface 102 of the crystal resonator 10 is covered by the second sealing member 30, and the internal space of the package, that is, the accommodation space of the vibrating portion 11 is hermetically sealed.

[0061] In the crystal oscillator 100, the sealing portions (seal paths) 115 and 116 that hermetically seal the vibrating portion 11 of the crystal vibrating plate 10 are formed in an annular shape in plan view. The seal path 115 is formed by diffusion bonding (Au-Au bonding) of the above-described first bonding pattern 121 on the vibrating plate side and the first bonding pattern 24 on the sealing member side, and the inner edge shape of the seal path 115 is formed in a substantially octagonal shape. The outer edge shape of the seal path 115 is formed in a substantially rectangular shape, and the outer peripheral edge of the seal path 115 is arranged close to the outer peripheral edge of the package. Similarly, the seal path 116 is formed by diffusion bonding (Au-Au bonding) of the above-described second bonding pattern 122 on the vibrating plate side and the second bonding pattern 31 on the sealing member side, and the inner edge shape of the seal path 116 is formed in a substantially octagonal shape. The outer edge shape of the seal path 116 is formed in a substantially rectangular shape, and the outer peripheral edge of the seal path 116 is arranged close to the outer peripheral edge of the package.

[0062] Also, the above-described connection bonding patterns and the interlayer wiring bonding patterns are also diffusion bonded in a superposed state. And by the bonding of the connection bonding patterns and the interlayer wiring bonding patterns, in the crystal oscillator 100, electrical conductivity is obtained between the first excitation electrode 111, the second excitation electrode 112, and the external electrode terminal 32. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32 via the first lead wiring 113, the wiring pattern 27, the second through hole 212, the first terminal 22, the third side surface wiring 271, the interlayer wiring bonding pattern 281, the interlayer wiring bonding pattern 181, the first side surface wiring 171, the interlayer wiring bonding pattern 183, the interlayer wiring bonding pattern 381, and the seventh side surface wiring 371 in this order.

[0063] Also, the second excitation electrode 112 is connected to the external electrode terminal 32 via the second lead wiring 114, the first through hole 162, the third through hole 213, the second terminal 23, the fourth side surface wiring 272, the interlayer wiring bonding pattern 282, the interlayer wiring bonding pattern 182, the second side surface wiring 172, the interlayer wiring bonding pattern 184, the interlayer wiring bonding pattern 382, and the eighth side surface wiring 372 in this order.

[0064] Furthermore, the metal film 28 is connected to earth (ground connection, using a part of the external electrode terminal 32) via the fifth side surface wiring 273, the seal path 115, the first internal wiring 173, the seal path 116, and the ninth side surface wiring 373 in this order. Similarly, the metal film 28 is connected to earth (ground connection, using a part of the external electrode terminal 32) via the sixth side surface wiring 274, the seal path 115, the second internal wiring 174, the seal path 116, and the tenth side surface wiring 374 in this order.

[0065] The first capacitor 501 is also connected to the wiring pattern 27 by a first capacitor connection electrode 502. Therefore, the first capacitor 501 is electrically connected to the first excitation electrode 111. Furthermore, the first capacitor 501 is connected to the metal film 28 by a first capacitor connection electrode 503 and a fourth through-hole 214. Therefore, the first capacitor 501 is connected to ground.

[0066] Moreover, the second capacitor 601 is connected to the connection bonding pattern 262 by the second capacitor connection electrode 602. Therefore, the second capacitor 601 is electrically connected to the second excitation electrode 112. Furthermore, the second capacitor 601 is connected to the metal film 28 by the second capacitor connection electrode 603 and the fifth through-hole 215. Therefore, the second capacitor 601 is connected to ground.

[0067] Furthermore, the first and second capacitors 501, 601 are preferably arranged so as not to overlap the first excitation electrode 111 and the second excitation electrode 112 when the quartz crystal resonator 100 is viewed from above (as viewed from the Y' direction).

[0068] In the crystal oscillator 100, each of the various bonding patterns described above may be formed such that a plurality of layers are laminated on the crystal plate, and a Ti (titanium) layer and an Au (gold) layer are formed by vapor deposition or sputtering from the lowermost layer side. Further, if other wirings and electrodes formed on the crystal oscillator 100 have the same configuration as the bonding pattern, the bonding pattern, the wiring, and the electrodes can be patterned simultaneously. Note that the lower electrode films 505 and 605 and the upper electrode films 504 and 604 constituting the first and second capacitors 501 and 601 may be formed by photolithography.

[0069] With the above configuration, a piezoelectric vibration device that can contribute to miniaturization of the circuit board can be provided. The crystal oscillator 100 includes a first capacitor 501 that is electrically connected to the first excitation electrode 111 and grounded, and a second capacitor 601 that is electrically connected to the second excitation electrode 112 and grounded. The first capacitor 501 and the second capacitor 601 are provided on the second main surface 202 of the first sealing member 20. With such a configuration, two capacitors that are essential when operating the crystal oscillator 100 as an oscillator can be mounted on the crystal oscillator 100. That is, it is no longer necessary to mount two capacitors that would originally need to be separately mounted on the circuit board from the crystal oscillator 100, reducing the occupied area of the circuit board and enabling further miniaturization of the circuit board. Further, the characteristics of the two capacitors constituting the oscillation circuit are generally determined by the characteristics of the crystal oscillator (the crystal oscillator 100 excluding the capacitors 501 and 601). However, with the configuration of the present invention, the crystal oscillator 100 can be provided with capacitors 501 and 601 corresponding to the characteristics of the crystal oscillator, and the burden of characteristic adjustment can be reduced when mounting on the circuit board to form an oscillation circuit.

[0070] Further, the first capacitor 501 and the second capacitor 601 are provided on the second main surface 202 of the first sealing member 20. That is, the first capacitor 501 and the second capacitor 601 are provided on the surface of the first sealing member 20 that faces the crystal vibrating plate 10. Therefore, the first capacitor 501 and the second capacitor 601 are arranged inside the internal space of the hermetically sealed crystal resonator 100 (package). With such a configuration, the first capacitor 501 and the second capacitor 601 can be arranged inside the hermetically sealed internal space. At this time, originally, since the silicon dioxide or titanium oxide forming the dielectric film 506 is microscopically porous, a change in capacitance over time due to moisture absorption or the like occurs. However, since the first capacitor 501 and the second capacitor 601 are arranged inside the hermetically sealed internal space, a change in capacitance over time due to moisture absorption or the like can be prevented.

[0071] Further, the first and second capacitors 501 and 601 include dielectric films 506 and 606, lower electrode films 505 and 605, and upper electrode films 504 and 604, and are thin film capacitors in which the lower electrode films 505 and 605, the dielectric films 506 and 606, and the upper electrode films 504 and 604 are laminated in this order. In other words, the first and second capacitors 501 and 601 are thin film capacitors having a laminated structure in which the dielectric films 506 and 606 are sandwiched between the lower electrode films 505 and 605 and the upper electrode films 504 and 604. With such a configuration, the first capacitor 501 and the second capacitor 601 can be mounted in the form of extremely thin films, and while realizing the low profile, which is an advantage of the crystal resonator 100 having a sandwich structure, the occupied area of the circuit board can be reduced, and the circuit board can be made smaller.

[0072] Further, when viewed in plan (from the Y' direction), the areas of the upper electrode films 504 and 604 of the first and second capacitors 501 and 601 are smaller than the areas of the lower electrode films 505 and 605 and the dielectric films 506 and 606. With such a configuration, when the upper electrode films 504 and 604 are formed (deposited) by sputtering, photolithography, or the like, even if the formation position is slightly deviated, it will not contact the lower electrode films 505 and 605 to cause a short circuit, nor will it deviate from the range of the lower electrode films 505 and 605 to change the capacitance, and a crystal oscillator 100 with stable characteristics can be obtained.

[0073] Also, the first and second capacitors 501 and 601 are arranged so as not to overlap with the first excitation electrode 111 and the second excitation electrode 112 when the crystal oscillator 100 is viewed in plan (from the Y' direction). With such a configuration, it is possible to prevent the first and second capacitors 501 and 601 from having an electrical influence on the first excitation electrode 111 and the second excitation electrode 112 and changing the characteristics of the crystal oscillator 100.

[0074] Note that the present invention is not limited to the configurations of the above-described embodiments, and many embodiments can be obtained. For example, in the present embodiment, the first and second capacitors 501 and 601 are provided on the second main surface 202 of the first sealing member 20, but they may be provided at any location on each main surface of the first sealing member 20 or the second sealing member 30. For example, the first and second capacitors 501 and 601 may be provided on the first main surface 201 of the first sealing member 20, or may be provided on the first main surface 301 of the second sealing member 30. Further, one of the first capacitor 501 and the second capacitor 601 may be provided on any main surface of the first sealing member 20, and the other may be provided on the first main surface 301 of the second sealing member 30.

[0075] Next, as another embodiment (second embodiment), an example in the case where the first and second capacitors are provided on the first main surface of the second sealing member will be described with reference to FIGS. 10 to 15. Note that the second embodiment has the same configuration as the first embodiment except that the first and second capacitors are provided on the first main surface of the second encapsulation member and the wiring pattern is changed accordingly. Therefore, in the description of the second embodiment, descriptions other than the description of the first and second capacitors provided on the first main surface of the second encapsulation member and the description of the wiring pattern associated therewith are omitted.

[0076] In the crystal diaphragm 110, the first excitation electrode 1111 is provided on the first main surface 1101 side of the vibrating portion 1011, and the second excitation electrode 1112 is provided on the second main surface 1102 side of the vibrating portion 1011. Lead wires (lead electrodes) for connecting these excitation electrodes to the external electrode terminals are connected to the first excitation electrode 1111 and the second excitation electrode 1112. The first lead wire 1113 is drawn from the first excitation electrode 1111, passes through the holding portion 1013, and is connected to a connection bonding pattern 1012a formed on the first main surface 1101 side of the outer frame portion 1012. Further, the connection bonding pattern 1012a is connected to a connection bonding pattern 1012e formed on the second main surface 1102 side of the outer frame portion 1012 via an internal wiring formed on the inner wall surface of the outer frame portion 1012. Also, the second lead wire 1114 is drawn from the second excitation electrode 1112, passes through the holding portion 1013, and is connected to a connection bonding pattern 1012d formed on the second main surface 1102 side of the outer frame portion 1012.

[0077] As shown in FIGS. 12 and 13, on both main surfaces (the first main surface 1101 and the second main surface 1102) of the crystal diaphragm 110, diaphragm-side sealing portions for joining the crystal diaphragm 110 to the first sealing member 1020 and the second sealing member 1030 are respectively provided. As the diaphragm-side sealing portion on the first main surface 1101, a diaphragm-side first bonding pattern 1121 is formed, and as the diaphragm-side sealing portion on the second main surface 1102, a diaphragm-side second bonding pattern 1122 is formed. The diaphragm-side first bonding pattern 1121 and the diaphragm-side second bonding pattern 1122 are provided on the outer frame portion 1012 and are formed in an annular shape in plan view. The outer peripheral edge of the diaphragm-side first bonding pattern 1121 is provided close to the outer peripheral edge of the first main surface 1101 of the crystal diaphragm 110 (outer frame portion 1012). The outer peripheral edge of the diaphragm-side second bonding pattern 1122 is provided close to the outer peripheral edge of the second main surface 1102 of the crystal diaphragm 110 (outer frame portion 1012). In the present embodiment, the diaphragm-side first bonding pattern 1121 and the diaphragm-side second bonding pattern 1122 are connected via the internal wiring 1017 formed on the inner wall surface of the outer frame portion 1012. The internal wiring 1017 is provided on the inner wall surface of the outer frame portion 1012 along the Z'-axis direction and on the inner wall surface on the -X direction side. Note that connection bonding patterns 1012b and 1012c are formed on the first main surface 1101 side of the outer frame portion 1012, and a connection bonding pattern 1012f is formed on the second main surface 1102 side of the outer frame portion 1012.

[0078] As shown in FIG. 11, on the second main surface 1202 of the first sealing member 120, a sealing member-side first bonding pattern 1024 as a sealing member-side first sealing portion for joining to the crystal diaphragm 110 is formed. The sealing member-side first bonding pattern 1024 is formed in an annular shape in plan view. The outer peripheral edge of the sealing member-side first bonding pattern 1024 is provided close to the outer peripheral edge of the second main surface 1202 of the first sealing member 120. Further, on the second main surface 1202 of the first sealing member 120, connection bonding patterns 1022a, 1022b, and 1022c for joining to the connection bonding patterns 1012a, 1012b, and 1012c formed on the first main surface 1101 of the outer frame portion 1012 of the crystal diaphragm 110 are formed.

[0079] As shown in FIG. 14, on the first main surface 1301 of the second sealing member 130, a sealing member side second bonding pattern 1031 as a sealing member side second sealing portion for bonding to the crystal vibrating plate 110 is formed. The sealing member side second bonding pattern 1031 is formed in an annular shape in plan view. The outer peripheral edge of the sealing member side second bonding pattern 1031 is provided close to the outer peripheral edge of the first main surface 1301 of the second sealing member 130. Also, on the first main surface 1301 of the second sealing member 130, connection bonding patterns 1034a, 1034b, 1034c for bonding to the connection bonding patterns 1012d, 1012e, 1012f formed on the second main surface 1102 of the outer frame portion 1012 of the crystal vibrating plate 110 are formed. The connection bonding patterns 1034a and 1034c are connected by a wiring pattern 1035 extending in the Z' - axis direction.

[0080] Also, on the first main surface 1301 of the second sealing member 130, a first capacitor 1501 and a second capacitor 1601 are provided. The first capacitor 1501 is connected to the connection bonding pattern 1034b by a first capacitor connection electrode 1502 and is connected to the sealing member side second bonding pattern 1031 by a first capacitor connection electrode 1503. Also, the second capacitor 1601 is connected to the wiring pattern 1035 by a second capacitor connection electrode 1602 and is connected to the sealing member side second bonding pattern 1031 by a second capacitor connection electrode 1603.

[0081] As shown in FIG. 15, on the second main surface 1302 (the outer main surface not facing the crystal vibrating plate 110) of the second sealing member 130, four external electrode terminals 1032 for electrically connecting to an external circuit board provided outside the crystal unit are provided. The external electrode terminals 1032 are formed in a substantially rectangular shape and are respectively located at the four corners (corner portions) of the second main surface 1302 of the second sealing member 130. The external electrode terminals 1032 are provided at positions overlapping the outer frame portion 1012 of the crystal vibrating plate 110 described above in plan view.

[0082] In the second sealing member 130, as shown in FIGS. 14 and 15, three through holes 1033a, 1033b, and 1033c are formed penetrating between the first main surface 1301 and the second main surface 1302. The through holes 1033a, 1033b, and 1033c are provided in the regions at the four corners (corners) of the second sealing member 130. Through electrodes for achieving electrical connection between the electrodes formed on the first main surface 1301 and the second main surface 1302 are formed along the inner wall surfaces of the respective through holes 1033a, 1033b, and 1033c. The through electrodes formed on the inner wall surfaces of the through holes 1033a, 1033b, and 1033c electrically connect the electrodes (connection bonding patterns) formed on the first main surface 1301 and the external electrode terminals 1032 formed on the second main surface 1302. Also, the central portion of each of the through holes 1033a, 1033b, and 1033c is a hollow through portion penetrating between the first main surface 1301 and the second main surface 1302.

[0083] In the crystal oscillator including the crystal vibrating plate 110, the first sealing member 120, and the second sealing member 130 having the above-described configuration, the crystal vibrating plate 110 and the first sealing member 120 are diffusion bonded in a state where the vibrating plate side first bonding pattern 1121 and the sealing member side first bonding pattern 1024 are overlapped, and the crystal vibrating plate 110 and the second sealing member 130 are diffusion bonded in a state where the vibrating plate side second bonding pattern 1122 and the sealing member side second bonding pattern 1031 are overlapped, thereby manufacturing a package having a sandwich structure. As a result, the internal space of the package, that is, the accommodation space for the vibrating portion 1011 is hermetically sealed.

[0084] At this time, the above-described connection bonding patterns are also diffusion-bonded in a superposed state. Then, by bonding the connection bonding patterns to each other, electrical continuity is obtained between the first excitation electrode 1111, the second excitation electrode 1112, and the external electrode terminals 1032, 1032 in the crystal oscillator. Specifically, the first excitation electrode 1111 is connected to the external electrode terminal 1032 via the first lead wiring 1113 and the through electrode of the through hole 1033a in sequence. The second excitation electrode 1112 is connected to the external electrode terminal 1032 via the second lead wiring 1114, the wiring pattern 1035, and the through electrode of the through hole 1033b in sequence.

[0085] Also, in the crystal oscillator according to the second embodiment, a sealing portion (seal path) for hermetically sealing the vibrating portion 1011 of the crystal vibrating plate 110 is formed. The seal path is composed of a first seal path formed by diffusion bonding (Au-Au bonding) of the above-described first bonding pattern 1121 on the vibrating plate side and the first bonding pattern 1024 on the sealing member side, and a second seal path formed by diffusion bonding (Au-Au bonding) of the above-described second bonding pattern 1122 on the vibrating plate side and the second bonding pattern 1031 on the sealing member side. The first and second seal paths are not electrically connected to the electrical conduction path between the first and second excitation electrodes 1111, 1112 and the external electrode terminals 1032, 1032. Specifically, the first seal path is connected to the second seal path via the internal wiring 1017, and further, the second seal path is grounded (ground connection, using a part of the external electrode terminal 1032) via the through electrode of the through hole 1033c.

[0086] Also, the first capacitor 1501 is connected to the connection bonding pattern 1034b by the first capacitor connection electrode 1502. Therefore, the first capacitor 1501 is electrically connected to the first excitation electrode 1111. Further, the first capacitor 1501 is connected to the second bonding pattern 1031 on the sealing member side by the first capacitor connection electrode 1503. Therefore, the first capacitor 1501 is grounded.

[0087] Further, the second capacitor 1601 is connected to the wiring pattern 1035 by the second capacitor connection electrode 1602. Therefore, the second capacitor 1601 is electrically connected to the second excitation electrode 1112. Further, the second capacitor 1601 is connected to the second bonding pattern 1031 on the sealing member side by the second capacitor connection electrode 1603. Therefore, the second capacitor 1601 is grounded.

[0088] Even with the configuration as in the above-described second embodiment, the same effects as those of the first embodiment can be obtained.

[0089] Also, in each of the embodiments in this specification, as an example of the vibrating portion 11, it has a substantially rectangular shape, has the first excitation electrode 111 on the first main surface 101, and has the second excitation electrode 112 on the second main surface 102. However, for example, the vibrating portion 11 may have a tuning fork shape, and may have the first excitation electrode 111 and the second excitation electrode 112 on each main surface of a pair of protruding vibrating arm portions (corresponding to the vibrating portion in each embodiment).

[0090] Also, in the first embodiment, four external electrode terminals 32 are provided, and a four-terminal configuration in which two of them are used as grounded terminals is exemplified. In the second embodiment, four external electrode terminals 1032 are provided, and a three-terminal configuration in which one of them is used as a grounded terminal is exemplified. However, the configuration of the external electrode terminals is not limited to these. That is, the number of external electrode terminals provided in the crystal oscillator (piezoelectric vibration device) of the present invention and the number of terminal configurations may be appropriately changed depending on the structure of the mounting substrate, the use of the piezoelectric vibration device, the function of the piezoelectric vibration device, and the like.

[0091] Also, in the first and second embodiments, the crystal vibration plate, the first sealing member, and the second sealing member are joined by diffusion bonding (Au-Au bonding). However, for example, a configuration joined by a brazing material such as AuSn solder may be used.

[0092] The embodiments disclosed this time are illustrative in all respects and do not serve as a basis for a limiting interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description in the claims. Also, all changes within the meaning and scope equivalent to the claims are included.

Industrial Applicability

[0093] The piezoelectric vibration device of the present invention can be used in the industries of manufacturing and selling piezoelectric vibration devices having a sandwich structure.

Explanation of Signs

[0094] 10…Quartz vibration plate (piezoelectric vibration plate) 20…First sealing member 22…First terminal 23…Second terminal 28…Metal film 30…Second sealing member 32…External electrode terminal 100…Quartz resonator (piezoelectric vibration device) 111…First excitation electrode 112…Second excitation electrode 201…First main surface 202…Second main surface 501…First capacitor 601…Second capacitor 504, 604…Upper electrode film 505, 605…Lower electrode film 506, 606…Dielectric film

Claims

1. A piezoelectric vibrating plate having a first excitation electrode formed on a main surface of a substrate and a second excitation electrode formed on the main surface of the substrate and paired with the first excitation electrode, and a first sealing member and a second sealing member covering both main surfaces of the piezoelectric vibrating plate, wherein, by joining the first sealing member and the piezoelectric vibrating plate and joining the second sealing member and the piezoelectric vibrating plate, an internal space in which a vibrating portion of the piezoelectric vibrating plate including the first excitation electrode and the second excitation electrode is hermetically sealed is provided. In the piezoelectric vibration device, a first capacitor electrically connected to the first excitation electrode, and a second capacitor electrically connected to the second excitation electrode are provided, the first capacitor is provided on a main surface of the first sealing member or the second sealing member, and the second capacitor is provided on a main surface of the first sealing member or the second sealing member Piezoelectric vibration device.

2. The first capacitor and the second capacitor are arranged in the internal space, and are provided on a main surface of the first sealing member or the second sealing member facing the piezoelectric vibrating plate The piezoelectric vibration device according to Claim 1.

3. The first capacitor and the second capacitor each include a dielectric film, a lower electrode film, and an upper electrode film, and have a laminated structure in which the dielectric film is sandwiched between the lower electrode film and the upper electrode film The piezoelectric vibration device according to Claim 1 or 2.

4. In a plan view, the area of the upper electrode film is smaller than the areas of the lower electrode film and the dielectric film The piezoelectric vibration device according to Claim 3.

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