Method for adjusting the frequency of a piezoelectric vibration device

Abstract

In the method for adjusting a frequency of a crystal vibrator (100), a frequency adjustment metal film (36), which is composed of a substrate metal layer (36a) and a metal layer (36b) laminated on the substrate metal layer, is formed on a first main surface (301) opposite to a second excitation electrode (112) of a second sealing member (30), and the second sealing member (30) is made of crystal. Frequency adjustment is performed by: irradiating the frequency adjustment metal film (36) with a laser beam from the outside of the second sealing member (30); transmitting the laser beam through the inside of the second sealing member (30), heating the substrate metal layer (36a), and evaporating at least a portion of the metal layer (36b) through melting thereof; and attaching the metal layer to the second excitation electrode (112).

Description

[Technical Field]

[0001] The present invention relates to a method for adjusting the frequency of a piezoelectric vibration device and a piezoelectric vibration device. [Background technology]

[0002] The present invention relates to a method for adjusting the frequency of a piezoelectric vibration device. By law Regarding.

[0003] When performing the frequency adjustment process after sealing the vibration part of the quartz crystal plate with a sealing material, a beam such as a laser is irradiated from outside the quartz crystal unit. In this case, if the beam output is too high, the excitation electrode of the vibration part may be damaged. In addition, debris or gas may be generated in the internal space of the quartz crystal unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5762811 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a method for adjusting the frequency of a piezoelectric vibration device that allows for easy frequency adjustment without degrading the characteristics of the piezoelectric vibration device even after the vibration portion of the piezoelectric vibration plate is sealed with a sealing member. 。 [Means for solving the problem]

[0006] The present invention provides a method for solving the above-mentioned problems as follows: That is, the present invention provides a method for adjusting the frequency of a piezoelectric vibration device in which at least a vibration portion of a piezoelectric vibration plate having a vibration portion on which an excitation electrode is formed is hermetically sealed by a sealing member, wherein a frequency-adjusting metal film made of a base metal layer and a metal layer laminated thereon is formed on a main surface of the sealing member facing the excitation electrode, and at least a portion of the sealing member on which the frequency-adjusting metal film is formed is made of a light-transmitting material, the frequency adjustment metal film is formed smaller than the excitation electrode, and an outer periphery of the frequency adjustment metal film is located inside an outer periphery of the excitation electrode in a plan view, The method is characterized in that a beam is irradiated onto the frequency adjustment metal film from outside the sealing member, and the beam is transmitted through the inside of the sealing member to heat the underlying metal layer, thereby melting and evaporating (vaporizing) at least a portion of the metal layer, and attaching it to the excitation electrode, thereby performing frequency adjustment.

[0007] According to the above-described frequency adjustment method for a piezoelectric vibration device, the metal layer above the underlying metal layer is melted and evaporated, and the evaporated metal adheres to the excitation electrode, thereby increasing the mass of the excitation electrode and shifting the frequency downward. In this case, the desired frequency adjustment amount can be obtained by controlling the beam output, irradiation time, etc. Furthermore, by preventing the beam from penetrating the frequency adjustment metal film, damage to the excitation electrode can be suppressed. This allows frequency adjustment to be performed without significantly degrading the characteristics of the piezoelectric vibration device, even after the vibration portion of the piezoelectric vibration plate is sealed with a sealing member.

[0008] In the above-described frequency adjustment method for a piezoelectric vibrating device, it is preferable to melt the metal layer by irradiating the beam without penetrating the underlying metal layer. In this way, the beam does not penetrate the frequency adjustment metal film, so that damage to the excitation electrode can be more reliably avoided. This allows easy frequency adjustment without degrading the characteristics of the piezoelectric vibrating device even after the vibration part of the piezoelectric diaphragm is sealed with a sealing member.

[0009] In the frequency adjustment method for a piezoelectric vibration device, the melting temperature (melting point) of the base metal layer of the frequency-adjusting metal film is preferably higher than the melting temperature of the metal layer. In this case, the difference between the melting temperature of the base metal layer and the melting temperature of the metal layer is preferably 350 K or more. Furthermore, if the metal layer is composed of multiple metal layers, the difference between the melting temperature of the base metal layer and the melting temperature of the uppermost metal layer is preferably 350 K or more. Because of this difference between the melting temperatures of the base metal layer and the metal layer, by irradiating the base metal layer with a beam to a temperature above the melting temperature of the metal layer but below the melting temperature of the base metal layer, the base metal layer does not melt, but only the metal layer melts, and some of the molten metal can be evaporated. The evaporated metal adheres to the excitation electrode, increasing the mass of the excitation electrode and shifting the frequency to a lower side. This allows easy frequency adjustment without degrading the characteristics of the piezoelectric vibration device, even after the vibration portion of the piezoelectric vibration plate is sealed with a sealing member.

[0010] In the above-described method for adjusting the frequency of a piezoelectric vibration device, it is preferable that the first main surface of the sealing member on which the frequency-adjusting metal film is formed and the second main surface opposite the first main surface are smooth surfaces. This makes it possible to suppress reflection and refraction of the beam when it enters the second main surface of the sealing member and when it exits the first main surface of the sealing member, thereby reducing energy loss of the beam. As a result, even after the vibration portion of the piezoelectric vibration plate is sealed with the sealing member, it is possible to perform high-precision frequency adjustment according to the beam output, irradiation time, etc.

[0011] In the above-described method for adjusting the frequency of a piezoelectric vibrating device, it is preferable that the metal layer is formed of the same material as the excitation electrodes. Since the metal layer is made of the same material as the excitation electrodes, the characteristics do not change before and after frequency adjustment, and therefore fluctuations in the characteristics of the piezoelectric vibrating device after sealing can be suppressed.

[0012] In the method for adjusting the frequency of a piezoelectric vibrating device, it is preferable that the base metal layer is formed of titanium, so that the base metal layer exposed to the internal space of the piezoelectric vibrating device functions as a getter material, thereby enabling the base metal layer to capture gas generated in the internal space of the piezoelectric vibrating device.

[0013] In the above-described frequency adjustment method for a piezoelectric vibrating device, the beam is preferably a visible light laser. By using a visible light laser that has low absorption and high transmittance with respect to a sealing material made of, for example, quartz or glass, power loss and damage to the sealing material can be reduced, making it suitable for frequency adjustment.

[0014] In the above-described frequency adjustment method for a piezoelectric vibrating device, it is preferable that the space in which the vibrating portion of the piezoelectric vibrating plate is sealed is a vacuum. This allows the evaporated metal to move in a substantially linear manner, thereby preventing it from scattering to the surroundings. Furthermore, the evaporated metal can be attached to the excitation electrode without lowering its temperature.

[0015] In the above-described frequency adjustment method for a piezoelectric vibration device, the vertical distance between the excitation electrode and the frequency-adjustment metal film is preferably 2 to 200 μm. By minimizing the distance between the excitation electrode and the frequency-adjustment metal film, the metal evaporated from the frequency-adjustment metal film can be made to move in a substantially linear manner, preventing it from scattering to the surroundings. This ensures that the evaporated metal adheres to the excitation electrode, making it easy to perform high-precision frequency adjustment even after the vibration portion of the piezoelectric vibration plate is sealed with a sealing member.

[0016] In the above-described frequency adjustment method for a piezoelectric vibration device, the piezoelectric vibration device includes a first sealing member covering a first main surface side of the vibration portion of the piezoelectric vibration plate and a second sealing member covering a second main surface side of the vibration portion of the piezoelectric vibration plate, and the first sealing member is bonded to the piezoelectric vibration plate and the second sealing member is bonded to the piezoelectric vibration plate, thereby hermetically sealing the vibration portion of the piezoelectric vibration plate, and it is preferable that the first sealing member and the second sealing member are made of quartz. In this way, when a piezoelectric vibration device with a three-layer structure is used, it is possible to reduce the size and thickness of the piezoelectric vibration device, and in such a reduced size and thickness piezoelectric vibration device, high-precision frequency adjustment can be performed even after the vibration portion of the piezoelectric vibration plate is sealed with the first and second sealing members. [Effects of the Invention]

[0021] According to the frequency adjustment method for a piezoelectric vibration device of the present invention, the metal layer above the base metal layer is melted and evaporated, and the evaporated metal adheres to the excitation electrode, thereby increasing the mass of the excitation electrode and shifting the frequency to a lower side. Furthermore, by preventing the beam from penetrating the frequency-adjusting metal film, damage to the excitation electrode can be suppressed. This allows frequency adjustment without significantly degrading the characteristics of the piezoelectric vibration device, even after the vibration part of the piezoelectric vibration plate is sealed with a sealing member. 。 [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing each component of a quartz crystal resonator according to an embodiment of the present invention; [Figure 2] 3 is a schematic plan view of a first main surface side of a first sealing member of a quartz crystal resonator. FIG. [Figure 3] 3 is a schematic plan view of the second main surface side of the first sealing member of the quartz crystal resonator. FIG. [Figure 4] 1 is a schematic plan view of a first main surface side of a quartz crystal plate according to an embodiment of the present invention. [Figure 5]2 is a schematic plan view of the second main surface side of the quartz crystal plate according to the present embodiment. FIG. [Figure 6] 3 is a schematic plan view of the first main surface side of the second sealing member of the quartz crystal resonator. FIG. [Figure 7] 4 is a schematic plan view of the second main surface side of the second sealing member of the quartz crystal resonator. FIG. [Figure 8] 1A to 1C are schematic cross-sectional views illustrating a method for adjusting the frequency of a crystal resonator according to an embodiment of the present invention. [Figure 9] 1 is a schematic cross-sectional view showing a metal film for adjusting the frequency of a quartz crystal resonator according to an embodiment of the present invention; [Figure 10] 8 and illustrates a method for adjusting the frequency of a crystal resonator according to a first modified example. [Figure 11] 8 and illustrates a method for adjusting the frequency of a crystal resonator according to a second modified example. [Figure 12] 8 is a diagram corresponding to FIG. 7 and illustrating a method for adjusting the frequency of a crystal resonator according to a third modified example. [Figure 13] 8 and illustrates a method for adjusting the frequency of a crystal resonator according to a fourth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following preferred embodiments, a piezoelectric resonator device to which the present invention is applied is a quartz resonator.

[0024] First, the basic structure of a quartz crystal unit 100 according to this embodiment will be described. As shown in Fig. 1, the quartz crystal unit 100 is configured to include a quartz crystal vibrating plate (piezoelectric vibrating plate) 10, a first sealing member 20, and a second sealing member 30. In this quartz crystal unit 100, the quartz crystal vibrating plate 10 is bonded to the first sealing member 20, and the quartz crystal vibrating plate 10 is bonded to the second sealing member 30, thereby forming a package with a substantially rectangular parallelepiped sandwich structure. That is, in the quartz crystal unit 100, the first sealing member 20 and the second sealing member 30 are bonded to both main surfaces of the quartz crystal vibrating plate 10, respectively, to form an internal space (cavity) of the package, and the vibrating unit 11 (see Figs. 4 and 5) is hermetically sealed in this internal space.

[0025] The crystal unit 100 according to this embodiment has a package size of, for example, 1.0 × 0.8 mm, and is designed to be compact and low-profile. To accommodate this compact design, the package does not have castellations, but rather uses through-holes (described below) to ensure electrical continuity between electrodes. The crystal unit 100 is also designed to be electrically connected to an external circuit board (not shown) via solder.

[0026] Next, the quartz crystal plate 10, the first sealing member 20, and the second sealing member 30 of the quartz crystal unit 100 will be described with reference to Figures 1 to 7. Note that the description here focuses on the individual components that are not bonded together and are configured as individual components. Figures 2 to 7 merely show one example of the configuration of the quartz crystal plate 10, the first sealing member 20, and the second sealing member 30, and are not intended to limit the scope of the present invention.

[0027] As shown in FIGS. 4 and 5, the quartz crystal vibrating plate 10 according to this embodiment is a piezoelectric substrate made of quartz crystal, and both of its main surfaces (first main surface 101 and second main surface 102) are polished (mirror-finished) to form flat, smooth surfaces. In this embodiment, an AT-cut quartz crystal plate that vibrates in thickness-shear mode is used as the quartz crystal vibrating plate 10. In the quartz crystal vibrating plate 10 shown in FIGS. 4 and 5, both main surfaces 101 and 102 of the quartz crystal vibrating plate 10 are in the XZ' plane. In this XZ' plane, the direction parallel to the short side (short side) of the quartz crystal vibrating plate 10 is the X-axis direction, and the direction parallel to the long side (long side) of the quartz crystal vibrating plate 10 is the Z'-axis direction. Note that AT-cut is a processing technique in which artificial quartz crystal is cut at an angle of 35°15' around the X-axis with respect to the Z-axis, one of the three crystal axes of the artificial quartz crystal: the electrical axis (X-axis), the mechanical axis (Y-axis), and the optical axis (Z-axis). In an AT-cut quartz plate, the X-axis coincides with the crystal axis of the quartz. The Y'-axis and Z'-axis coincide with axes tilted approximately 35°15' from the Y-axis and Z-axis of the quartz crystal (this cutting angle can be changed slightly to adjust the frequency-temperature characteristics of the AT-cut quartz plate). The Y'-axis and Z'-axis directions correspond to the cutting direction when the AT-cut quartz plate is cut.

[0028] A pair of excitation electrodes (first excitation electrode 111 and second excitation electrode 112) are formed on both main surfaces 101, 102 of the quartz crystal vibration plate 10. The quartz crystal vibration plate 10 has a substantially rectangular vibrating portion 11, an outer frame portion 12 that surrounds the outer periphery of the vibrating portion 11, and a holding portion (connecting portion) 13 that holds the vibrating portion 11 by connecting the vibrating portion 11 and the outer frame portion 12. In other words, the quartz crystal vibration plate 10 is configured such that the vibrating portion 11, the outer frame portion 12, and the holding portion 13 are integrally formed. The holding portion 13 extends (protrudes) in the -Z' direction from only one corner of the vibrating portion 11 located in the +X direction and the -Z' direction to the outer frame portion 12. A through portion (slit) 10a that penetrates the thickness of the quartz crystal vibration plate 10 is provided between the vibrating portion 11 and the outer frame portion 12. In this embodiment, the quartz crystal vibration plate 10 is provided with only one holding portion 13 that connects the vibration portion 11 and the outer frame portion 12, and the through portion 10a is formed continuously so as to surround the outer periphery of the vibration portion 11.

[0029] The first excitation electrode 111 is provided on the first main surface 101 side of the vibrating section 11, and the second excitation electrode 112 is provided on the second main surface 102 side of the vibrating section 11. Input / output lead-out wiring (first lead-out wiring 113, second lead-out wiring 114) is connected to the first excitation electrode 111 and the second excitation electrode 112 to connect these excitation electrodes to external electrode terminals. The first lead-out wiring 113 on the input side is led out from the first excitation electrode 111 and connected to a connection bonding pattern 14 formed on the outer frame section 12 via a holding section 13. The second lead-out wiring 114 on the output side is led out from the second excitation electrode 112 and connected to a connection bonding pattern 15 formed on the outer frame section 12 via a holding section 13.

[0030] Both main surfaces (first main surface 101, second main surface 102) of the quartz crystal vibrating plate 10 are provided with diaphragm-side sealing portions for bonding the quartz crystal vibrating plate 10 to the first sealing member 20 and the second sealing member 30. A diaphragm-side first bonding pattern 121 is formed as the diaphragm-side sealing portion on the first main surface 101, and a diaphragm-side second bonding pattern 122 is formed as the diaphragm-side sealing portion on the second main surface 102. The diaphragm-side first bonding pattern 121 and the diaphragm-side second bonding pattern 122 are provided on the outer frame portion 12 and are formed in an annular shape in a plan view.

[0031] As shown in FIGS. 4 and 5, five through holes are formed in the quartz-crystal vibrating plate 10, penetrating between the first main surface 101 and the second main surface 102. Specifically, the four first through holes 161 are provided in the four corner regions of the outer frame portion 12. The second through hole 162 is provided in the outer frame portion 12 on one side of the vibrating portion 11 in the Z′-axis direction (the −Z′ direction side in FIGS. 4 and 5). A connection bonding pattern 123 is formed around each of the first through holes 161. A connection bonding pattern 124 is formed on the first main surface 101 side of the second through hole 162, and a connection bonding pattern 15 is formed on the second main surface 102 side of the second through hole 162.

[0032] The first through-holes 161 and the second through-holes 162 have through-hole electrodes formed along their inner walls to connect the electrodes formed on the first main surface 101 and the second main surface 102. The central portions of the first through-holes 161 and the second through-holes 162 form hollow through-holes that penetrate between the first main surface 101 and the second main surface 102. The outer peripheral edge of the diaphragm-side first bonding pattern 121 is located close to the outer peripheral edge of the first main surface 101 of the quartz-crystal vibrating plate 10 (outer frame 12). The outer peripheral edge of the diaphragm-side second bonding pattern 122 is located close to the outer peripheral edge of the second main surface 102 of the quartz-crystal vibrating plate 10 (outer frame 12). In this embodiment, an example has been given in which five through holes are formed between the first main surface 101 and the second main surface 102, but instead of forming through holes, it is also possible to cut out a portion of the side surface of the first sealing member 20 and form a castellation with an electrode coated on the inner wall surface of the cut-out area (the same applies to the second sealing member 30).

[0033] 2 and 3, the first sealing member 20 is a rectangular parallelepiped substrate formed from a single AT-cut quartz crystal plate, which is a translucent material. The second main surface 202 of this first sealing member 20 (the surface that bonds to the quartz crystal vibrating plate 10) is polished (mirror-finished) to a flat, smooth surface. Although the first sealing member 20 does not have a vibrating part, by using an AT-cut quartz crystal plate like the quartz crystal vibrating plate 10, the thermal expansion coefficients of the quartz crystal vibrating plate 10 and the first sealing member 20 can be made the same, thereby suppressing thermal deformation of the quartz crystal unit 100. The X-, Y-, and Z'-axes of the first sealing member 20 are also oriented in the same directions as those of the quartz crystal vibrating plate 10.

[0034] As shown in FIG. 2, first and second wiring terminals 22 and 23 and a metal film 28 for shielding (ground connection) are formed on the first main surface 201 of the first sealing member 20 (the outer main surface not facing the quartz-crystal vibrating plate 10). The first and second wiring terminals 22 and 23 are provided as wiring for electrically connecting the first and second excitation electrodes 111 and 112 of the quartz-crystal vibrating plate 10 to the external electrode terminal 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, with the first terminal 22 on the +Z′-direction side and the second terminal 23 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.

[0035] The metal film 28 is provided between the first and second terminals 22, 23 and is arranged at a predetermined distance from the first and second terminals 22, 23. The metal film 28 is provided in almost all of the regions of the first main surface 201 of the first sealing member 20 where the first and second terminals 22, 23 are not formed. The metal film 28 is provided from the end of the first main surface 201 of the first sealing member 20 in the +X direction to the end in the −X direction.

[0036] 2 and 3, six through holes are formed in the first sealing member 20, penetrating between the first main surface 201 and the second main surface 202. Specifically, four third through holes 211 are provided in the four corner (corner) regions of the first sealing member 20. Fourth and fifth through holes 212, 213 are provided in the +Z' direction and -Z' direction in FIGS. 2 and 3, respectively.

[0037] In the third through hole 211 and the fourth and fifth through holes 212, 213, through electrodes for establishing electrical continuity 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 respective through holes. The central portions of the third through hole 211 and the fourth and fifth through holes 212, 213 form hollow through portions that penetrate between the first main surface 201 and the second main surface 202. The through electrodes of two third through holes 211, 211 located diagonally on the first main surface 201 of the first sealing member 20 (the third through hole 211 located at the corner in the +X direction and the +Z′ direction in FIGS. 2 and 3 , and the third through hole 211 located at the corner in the −X direction and the −Z′ direction) are electrically connected to each other by the metal film 28. Furthermore, the through electrode of the third through hole 211 located at the corner in the −X direction and the +Z′ direction and the through electrode of the fourth through hole 212 are electrically connected by the first terminal 22. The through electrode of the third through hole 211 located at the corner in the +X direction and the −Z′ direction and the through electrode of the fifth through hole 213 are electrically connected by the second terminal 23.

[0038] A sealing member-side first bonding pattern 24 is formed on the second main surface 202 of the first sealing member 20 as a sealing member-side first sealing portion for bonding to the quartz-crystal vibrating plate 10. The sealing member-side first bonding pattern 24 is formed in an annular shape in a plan view. Furthermore, on the second main surface 202 of the first sealing member 20, connection bonding patterns 25 are formed around the third through holes 211. A connection bonding pattern 261 is formed around the fourth through hole 212, and a connection bonding pattern 262 is formed around the fifth through hole 213. Furthermore, a connection bonding pattern 263 is formed on the opposite side of the connection bonding pattern 261 in the longitudinal direction of the first sealing member 20 (the -Z' direction side), and the connection bonding pattern 261 and the connection bonding pattern 263 are connected by a wiring pattern 27. The outer periphery of the sealing member-side first bonding pattern 24 is provided close to the outer periphery of the second main surface 202 of the first sealing member 20.

[0039] 6 and 7, the second sealing member 30 is a rectangular parallelepiped substrate formed from a single AT-cut quartz crystal plate, which is a light-transmitting material, and the first main surface 301 (the surface that bonds to the quartz crystal plate 10) and the second main surface 302 (the outer main surface that does not face the quartz crystal plate 10) of this second sealing member 30 are polished to a flat, smooth surface. Note that the second sealing member 30 also uses an AT-cut quartz crystal plate like the quartz crystal plate 10, and it is desirable that the orientations of the X-axis, Y-axis, and Z'-axis are the same as those of the quartz crystal plate 10.

[0040] A sealing member-side second bonding pattern 31 is formed on the first main surface 301 of the second sealing member 30 as a sealing member-side second sealing portion for bonding to the quartz-crystal vibrating plate 10. The sealing member-side second bonding pattern 31 is formed in an annular shape in a plan view. The outer periphery of the sealing member-side second bonding pattern 31 is provided close to the outer periphery of the first main surface 301 of the second sealing member 30.

[0041] Furthermore, a frequency-adjusting metal film 36 used to adjust the frequency of the quartz crystal resonator 100 is formed on the first main surface 301 of the second sealing member 30. The frequency-adjusting metal film 36 has a two-layer structure made of two types of metal with different melting temperatures (melting points). As shown in FIG. 8 , the frequency-adjusting metal film 36 includes a base metal layer 36a and a metal layer 36b laminated on the base metal layer 36a. The base metal layer 36a is preferably 50 nm thick, and the metal layer 36b is preferably 100 nm thick. The base metal layer 36a is preferably 50 to 500 nm thick, and the metal layer 36b is preferably 100 to 500 nm thick. A thickness of less than 50 nm for the base metal layer 36a is not preferable because it cannot withstand laser irradiation. A thickness of more than 500 nm for the base metal layer 36a is not preferable because it causes wafer warping and reduces production efficiency due to the thick film. Furthermore, if the thickness of the metal layer 36b is less than 100 nm, it is not preferable because it cannot withstand laser irradiation, and if the thickness of the metal layer 36b is more than 500 nm, it is not preferable because the wafer warps and the thick film reduces production efficiency.

[0042] The base metal layer 36a is made of, for example, Ti (titanium), and the metal layer 36b is made of the same material (for example, Au) as the second excitation electrode 112. The melting temperature of the base metal layer 36a is higher than that of the metal layer 36b. The difference between the melting temperatures of the base metal layer 36a and the metal layer 36b is preferably 350 K or more. When the base metal layer 36a is made of Ti (titanium), the melting temperature is approximately 1941 K. When the metal layer 36b is made of Au (gold), the melting temperature is approximately 1337 K. The difference between the melting temperatures of the base metal layer 36a and the metal layer 36b is approximately 604 K. Note that the base metal layer 36a may be made of, for example, Ni (nickel). The metal layer 36b may have a multilayer structure made of multiple metal layers, in which case the uppermost metal layer may be made of the same material (for example, Au) as the second excitation electrode 112.

[0043] The frequency adjustment metal film 36 is provided at a position facing the second excitation electrode 112 at a predetermined interval. The distance L1 in the vertical direction (Y-axis direction) between the second excitation electrode 112 and the frequency adjustment metal film 36 is 2 to 200 μm.

[0044] The frequency adjustment metal film 36 is formed in a substantially rectangular shape in a plan view. The frequency adjustment metal film 36 is formed slightly smaller than the second excitation electrode 112, and the outer periphery of the frequency adjustment metal film 36 is located inside the outer periphery of the second excitation electrode 112 in a plan view. Furthermore, at least a part of the base metal layer 36a is not covered by the metal layer 36b and is exposed, and a step portion 36c (FIG. 9) is formed inside the frequency adjustment metal film 36. With this configuration, even if the exposed part of the base metal layer 36a of the frequency adjustment metal film 36 comes into contact with the second excitation electrode 112 when the vibrating unit 11 is bent due to an external impact, adhesion (sticking) between the base metal layer 36a and the second excitation electrode 112 can be prevented.

[0045] The first and second main surfaces 301, 302 of the second sealing member 30 are polished to form smooth surfaces, and the arithmetic mean roughness Ra of the first and second main surfaces 301, 302 is 1 nm or less. In addition, the arithmetic mean roughness Ra of the surface of the metal layer 36b of the frequency-adjusting metal film 36 is 3 nm or less.

[0046] Four external electrode terminals 32 are provided on the second main surface 302 of the second sealing member 30. The external electrode terminals 32 are electrically connected to an external circuit board provided outside the quartz crystal unit 100. The external electrode terminals 32 are located at the four corners (corner portions) of the second main surface 302 of the second sealing member 30.

[0047] As shown in FIGS. 6 and 7 , the second sealing member 30 has four through holes formed therein that penetrate between the first main surface 301 and the second main surface 302. Specifically, the four sixth through holes 33 are provided in the four corner regions (corner portions) of the second sealing member 30. In the sixth through holes 33, through electrodes are formed along the inner wall surfaces of the sixth through holes 33 to ensure electrical continuity between the electrodes formed on the first main surface 301 and the second main surface 302. The through electrodes formed on the inner wall surfaces of the sixth through holes 33 in this manner provide electrical continuity between the electrodes formed on the first main surface 301 and the external electrode terminals 32 formed on the second main surface 302. The central portions of the sixth through holes 33 form hollow through portions that penetrate between the first main surface 301 and the second main surface 302. Furthermore, on the first main surface 301 of the second sealing member 30, connection bonding patterns 34 are formed around the sixth through holes 33, respectively.

[0048] In the quartz crystal unit 100 including the quartz crystal vibrating plate 10, first sealing member 20, and second sealing member 30 configured as described above, the quartz crystal vibrating plate 10 and the first sealing member 20 are diffusion bonded together with the first vibration plate bonding pattern 121 and the first sealing member bonding pattern 24 overlapping each other, and the quartz crystal vibrating plate 10 and the second sealing member 30 are diffusion bonded together with the second vibration plate bonding pattern 122 and the second sealing member bonding pattern 31 overlapping each other, thereby producing a sandwich-structured package as shown in Fig. 1. This hermetically seals the internal space of the package, i.e., the space housing the vibrating unit 11.

[0049] At this time, the connection bonding patterns are also diffusion bonded while overlapping each other. By bonding the connection bonding patterns together, electrical continuity is achieved among the first excitation electrode 111, the second excitation electrode 112, and the external electrode terminal 32 in the quartz crystal unit 100. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32 via the first extension wiring 113, the wiring pattern 27, the fourth through-hole 212, the first terminal 22, the third through-hole 211, the first through-hole 161, and the sixth through-hole 33, in that order. The second excitation electrode 112 is connected to the external electrode terminal 32 via the second extension wiring 114, the second through-hole 162, the fifth through-hole 213, the second terminal 23, the third through-hole 211, the first through-hole 161, and the sixth through-hole 33, in that order. Furthermore, the metal film 28 is connected to earth (ground connection, using part of the external electrode terminal 32) via the third through-hole 211, the first through-hole 161, and the sixth through-hole 33 in this order.

[0050] In the quartz crystal unit 100, the various bonding patterns are preferably formed by stacking multiple layers on the quartz crystal plate, with a Ti (titanium) layer and an Au (gold) layer formed from the bottom layer onwards by vapor deposition or sputtering. Furthermore, if the other wiring and electrodes formed on the quartz crystal unit 100 have the same configuration as the bonding patterns, the bonding patterns, wiring and electrodes can be patterned simultaneously, which is also preferable.

[0051] In the quartz crystal resonator 100 configured as described above, the sealing portions (seal paths) 115, 116 that hermetically seal the vibrating portion 11 of the quartz crystal vibrating plate 10 are formed in an annular shape in a plan view. The seal path 115 is formed by diffusion bonding (Au-Au bonding) the above-mentioned diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24, and the outer and inner edge shapes of the seal path 115 are formed in a substantially octagonal shape. Similarly, the seal path 116 is formed by diffusion bonding (Au-Au bonding) the above-mentioned diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31, and the outer and inner edge shapes of the seal path 116 are formed in a substantially octagonal shape.

[0052] Next, a frequency adjustment method for the quartz crystal resonator 100 according to this embodiment will be described with reference to Fig. 8. The frequency adjustment in this embodiment is a process of adjusting the mass of the second excitation electrode 112 of the vibration portion 11 of the quartz crystal vibrating plate 10 to adjust the oscillation frequency to a desired value. The frequency adjustment is performed on each of the quartz crystal resonators 100 in a wafer state during the manufacturing process of the quartz crystal resonators 100, but it may also be performed on each of the quartz crystal resonators 100 that have been singulated from the wafer state.

[0053] 8, the frequency is adjusted by irradiating the frequency-adjusting metal film 36 with a laser from outside the second sealing member 30, transmitting the laser through the inside of the second sealing member 30 to heat the base metal layer 36a, thereby melting and evaporating (vaporizing) at least a part of the metal layer 36b, and attaching the evaporated metal to the second excitation electrode 112. In other words, the laser melts and evaporates the metal layer 36b above the base metal layer 36a, and the evaporated metal attaches to the second excitation electrode 112, thereby increasing the mass of the second excitation electrode 112 and shifting the frequency to a lower side.

[0054] The laser is irradiated perpendicularly onto the second sealing member 30. A visible light laser capable of transmitting through the second sealing member 30 made of quartz crystal is used as the laser. Specifically, a green laser with a wavelength of approximately 532 nm can be used. The laser output is adjusted to a value that does not penetrate the base metal layer 36a of the frequency adjustment metal film 36. The laser heats the base metal layer 36a, which in turn heats the metal layer 36b above the base metal layer 36a. As described above, the melting temperature of the base metal layer 36a is higher than the melting temperature of the metal layer 36b. Therefore, when the base metal layer 36a is heated to a temperature higher than the melting temperature of the metal layer 36b, the metal layer 36b melts, and a portion of the melted metal layer 36b evaporates. Since the inside of the quartz crystal unit 100 is a vacuum, the evaporated metal moves upward in a substantially straight line, and when it reaches the surface 112a of the second excitation electrode 112, it is cooled and solidified on the surface 112a of the second excitation electrode 112. As a result, the metal evaporated from the frequency-adjusting metal film 36 adheres to the surface 112a of the second excitation electrode 112.

[0055] By controlling the number of laser pulses irradiated onto the metal base layer 36a, the sweep distance, the number of sweeps, etc., it is possible to control the mass of metal adhering to the second excitation electrode 112, and therefore the amount of frequency adjustment. For example, by continuously irradiating the laser with a low laser output and a narrow pulse interval, it is possible to efficiently heat the metal base layer 36a and evaporate only the metal layer 36b. In this case, it is possible to obtain the amount of frequency adjustment according to the laser sweep distance, enabling highly accurate frequency adjustment.

[0056] According to the frequency adjustment method for the quartz crystal unit 100 of this embodiment, the metal layer 36b above the base metal layer 36a is melted and evaporated, and the evaporated metal adheres to the second excitation electrode 112, thereby increasing the mass of the second excitation electrode 112 and shifting the frequency to a lower value. In this case, the desired frequency adjustment amount can be obtained by controlling the number of laser pulses, sweep distance, etc. Furthermore, by preventing the laser from penetrating the frequency adjustment metal film 36, damage to the second excitation electrode 112 can be suppressed. As a result, frequency adjustment can be performed without significantly degrading the characteristics of the quartz crystal unit 100, even after the vibration portion 11 of the quartz crystal vibrating plate 10 is sealed with the first and second sealing members 20 and 30.

[0057] In this embodiment, the laser is irradiated so as not to penetrate the base metal layer 36a, and the laser does not penetrate the frequency adjustment metal film 36, which more reliably avoids damaging the second excitation electrode 112. This makes it possible to easily adjust the frequency without degrading the characteristics of the quartz crystal unit 100, even after the vibrating portion 11 of the quartz crystal vibrating plate 10 is sealed with the first and second sealing members 20 and 30.

[0058] In this embodiment, the difference between the melting temperature of the metal base layer 36a and the melting temperature of the metal layer 36b is 350 K or more. By irradiating the metal base layer 36a with a laser to a temperature equal to or higher than the melting temperature of the metal layer 36b but lower than the melting temperature of the metal base layer 36a, the metal base layer 36a does not melt, but only the metal layer 36b melts, and some of the molten metal can be evaporated. The evaporated metal adheres to the second excitation electrode 112, increasing the mass of the second excitation electrode 112 and shifting the frequency to a lower level. This allows for easy frequency adjustment without degrading the characteristics of the crystal unit 100, even after the vibration portion 11 of the crystal vibrating plate 10 is sealed with the first and second sealing members 20 and 30.

[0059] In this embodiment, the first main surface 301 of the second sealing member 30 and the second main surface 302 opposite to the first main surface 301 are smooth surfaces, which can suppress reflection and refraction of the laser when the laser is incident on the second main surface 302 of the second sealing member 30 and when the laser is emitted from the first main surface 301 of the second sealing member 30, thereby reducing laser energy loss. As a result, even after the vibrating portion 11 of the quartz crystal vibrating plate 10 is sealed with the first and second sealing members 20 and 30, high-precision frequency adjustment can be performed according to the number of laser pulses, sweep distance, number of sweeps, etc.

[0060] Furthermore, the metal layer 36b is formed from the same Au (gold) as the second excitation electrode 112, and since the metal layer 36b is made of the same material as the second excitation electrode 112, the characteristics do not change before and after frequency adjustment, and therefore fluctuations in the characteristics of the quartz crystal resonator 100 after sealing can be suppressed.

[0061] Furthermore, the metal underlayer 36a is formed of Ti (titanium), and the metal underlayer 36a exposed to the internal space of the quartz crystal unit 100 functions as a getter material, thereby enabling the metal underlayer 36a to capture gas generated in the internal space of the quartz crystal unit 100. The metal underlayer 36a may also be formed of W (tungsten), in which case the difference in melting temperature between the metal underlayer 36a (W) and the metal layer 36b (Au) thereover can be made even larger, for example, 1500K or higher.

[0062] Furthermore, by using a visible light laser that has low absorption and high transmittance for the second sealing member 30 made of, for example, quartz or glass, as the laser, it is possible to reduce power loss and damage to the second sealing member 30, making it suitable for frequency adjustment.

[0063] Furthermore, the space sealing the vibration part 11 of the quartz crystal vibration plate 10 is a vacuum, allowing the evaporated metal to move in a substantially linear manner, thereby preventing it from scattering to the surroundings. Furthermore, the evaporated metal can be attached to the second excitation electrode 112 without lowering its temperature.

[0064] In this embodiment, the vertical distance L1 between the second excitation electrode 112 and the frequency adjustment metal film 36 is 2 to 200 μm. By minimizing the distance L1 between the second excitation electrode 112 and the frequency adjustment metal film 36, the metal evaporated from the frequency adjustment metal film 36 moves in a substantially linear manner, preventing it from scattering to the surroundings. This ensures that the evaporated metal adheres to the second excitation electrode 112, and makes it easy to perform high-precision frequency adjustment even after the vibration portion 11 of the quartz crystal vibration plate 10 is sealed with the first and second sealing members 20 and 30.

[0065] Furthermore, since the outer peripheral edge of the frequency-adjusting metal film 36 is located inside the outer peripheral edge of the second excitation electrode 112 in plan view, even if an exposed portion of the base metal layer 36a of the frequency-adjusting metal film 36 comes into contact with the second excitation electrode 112 when the vibrating portion 11 is bent due to an external impact, adhesion between the base metal layer 36a and the second excitation electrode 112 can be prevented. Furthermore, metal evaporated from the frequency-adjusting metal film 36 can be prevented from scattering outside the second excitation electrode 112, and the evaporated metal can be reliably adhered to the second excitation electrode 112. This makes it easy to perform high-precision frequency adjustment even after the vibrating portion 11 of the quartz crystal vibrating plate 10 is sealed with the first and second sealing members 20 and 30.

[0066] In this embodiment, the quartz crystal unit 100 includes a first sealing member 20 that covers the first main surface of the vibrating portion 11 of the quartz crystal vibrating plate 10, and a second sealing member 30 that covers the second main surface of the vibrating portion 11 of the quartz crystal vibrating plate 10. The first sealing member 20 and the quartz crystal vibrating plate 10 are bonded together, and the second sealing member 30 is bonded together, thereby hermetically sealing the vibrating portion 11 of the quartz crystal vibrating plate 10. The first sealing member 20 and the second sealing member 30 are made of quartz crystal. Using a three-layer structure like this makes it possible to reduce the size and thickness of the quartz crystal unit 100. Even after sealing the vibrating portion 11 of the quartz crystal vibrating plate 10 with the first and second sealing members 20 and 30, the size and thickness of the reduced-size and reduced-thickness quartz crystal unit 100 can be adjusted with high precision.

[0067] Furthermore, in the quartz crystal resonator 100 of the present embodiment described above, the frequency-adjusting metal film 36 is formed on the first main surface 301 of the second sealing member 30, facing the second excitation electrode 112, and at least a portion of the base metal layer 36a of the frequency-adjusting metal film 36 is exposed and not covered by the metal layer 36b. This allows the exposed base metal layer 36a to function as a getter material, thereby capturing gas generated in the internal space of the quartz crystal resonator 100. Titanium, for example, is a preferred material for such base metal layer 36a. This makes it possible to suppress changes in the frequency of the quartz crystal resonator 100 over time due to gas generation.

[0068] Furthermore, since the quartz crystal vibration plate 10 is configured to include a vibration portion 11 and an outer frame portion 12 that surrounds the vibration portion 11, the distance L1 between the second excitation electrode 112 and the frequency adjustment metal film 36 can be made very small compared to a configuration in which a sealing member is bonded to a base using adhesive, and as described above, high-precision frequency adjustment can be performed.

[0069] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the scope of the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

[0070] In the above embodiment, the frequency adjustment metal film 36 is provided on the first main surface 301 of the second sealing member 30 facing the second excitation electrode 112. However, as shown in Modification 1 of FIG. 10 , the second sealing member 30 may not be provided with a frequency adjustment metal film, but may be provided on the second main surface 202 of the first sealing member 20 facing the first excitation electrode 111. Alternatively, as shown in Modification 2 of FIG. 11 , the frequency adjustment metal film 26 may be provided on the second main surface 202 of the first sealing member 20, and the frequency adjustment metal film 36 may be provided on the first main surface 301 of the second sealing member 30. The frequency adjustment metal film 26 of the first sealing member 20 has a configuration similar to that of the frequency adjustment metal film 36 of the second sealing member 30 of the above embodiment. The frequency adjustment metal film 26 has a laminated configuration including a base metal layer 26a made of, for example, Ti (titanium) and a metal layer 26b made of the same material as the first excitation electrode 111 (for example, Au).

[0071] 10 and 11, an opening that is rectangular in plan view is formed in the shielding metal film 28 formed on the first main surface 201 of the first sealing member 20, thereby enabling frequency adjustment by the frequency-adjusting metal film 26. The opening is preferably formed to be slightly larger than the frequency-adjusting metal film 26, and is positioned so that the frequency-adjusting metal film 26 fits within the opening in plan view.

[0072] According to the second modification of Fig. 11, frequency adjustment can be performed using both the frequency-adjustment metal films 26, 36. By irradiating the frequency-adjustment metal film 26 on the first sealing member 20 side of the quartz crystal resonator 100 with a laser, frequency adjustment can be performed at two locations, on the first sealing member 20 side and the second sealing member 30 side. In this case, frequency adjustment can be performed simultaneously at two locations, on the first sealing member 20 side and the second sealing member 30 side, or frequency adjustment can be performed at each location in turn. Alternatively, frequency adjustment can be performed first using the frequency-adjustment metal film 36, and if the amount of frequency adjustment is insufficient compared to the desired amount of frequency adjustment, frequency adjustment can be performed using the frequency-adjustment metal film 26 by an amount that compensates for the shortfall.

[0073] In the above embodiment, the external electrode terminal 32 provided on the second main surface 302 of the second sealing member 30 is rectangular (see FIG. 7 ). However, as shown in Modification 3 of FIG. 12 , the external electrode terminal 32 may be formed in an L-shape. In this case, it is preferable to arrange the external electrode terminal 32 so that it does not overlap with the internal space of the package in a plan view. By forming the external electrode terminal 32 in an L-shape in this way, even if the frequency-adjusting metal film 36 is made larger, the external electrode terminal 32 and the frequency-adjusting metal film 36 do not overlap with each other in a plan view. This makes it possible to ensure a larger amount of frequency adjustment.

[0074] In the above embodiment, the frequency adjustment is performed using a visible light laser, but the frequency adjustment may also be performed using a beam such as an electron beam, etc. In this case, the desired frequency adjustment amount can be obtained by controlling the beam output, irradiation time, etc.

[0075] In the above embodiment, the step portion 36c (FIG. 9) is provided on the central side of the frequency-adjusting metal film 36 to expose the underlying metal layer 36a, but the step portion 36c may be provided on at least a part of the frequency-adjusting metal film 36. Furthermore, the underlying metal layer 36a may be exposed at a location other than the outer periphery as long as it is a location that is not irradiated with a laser.

[0076] In the above embodiment, the internal space of the quartz crystal unit 100 is evacuated, but the internal space of the quartz crystal unit 100 may be filled with low-pressure nitrogen, argon, or the like.

[0077] In the above embodiment, the quartz crystal vibrating plate 10 is an AT-cut quartz crystal plate, but other materials may be used. Also, while the vibrating portion 11 of the quartz crystal vibrating plate 10 is rectangular, the vibrating portion may be shaped like a tuning fork.

[0078] In the above embodiment, the first sealing member 20 and the second sealing member 30 are formed from quartz plates, but the first sealing member 20 and the second sealing member 30 may be formed from, for example, glass. In this case, an infrared laser that can transmit through the first sealing member 20 and the second sealing member 30 may be used. As the infrared laser, for example, a YAG laser with a wavelength of approximately 1064 nm may be used. Note that only a portion of the first sealing member 20 and the second sealing member 30 may be formed from a light-transmitting material such as quartz or glass.

[0079] In the above embodiment, the quartz crystal vibration plate 10 is provided with only one holding portion 13 connecting the vibrating portion 11 and the outer frame portion 12, but two or more holding portions 13 may be provided. Also, a through portion 10a that penetrates the quartz crystal vibration plate 10 in the thickness direction is provided between the vibrating portion 11 and the outer frame portion 12, but a quartz crystal vibration plate configured without a through portion may also be used. Also, in the above embodiment, a framed quartz crystal vibration plate 10 is used that includes the vibrating portion 11 and the outer frame portion 12 that surrounds the vibrating portion 11, but a quartz crystal vibration plate configured without an outer frame portion may also be used.

[0080] In the above embodiment, the number of external electrode terminals 32 on the second main surface 302 of the second sealing member 30 is four, but this is not limited thereto and the number of external electrode terminals 32 may be, for example, two, six, or eight. Furthermore, while the present invention has been described as being applied to the quartz crystal resonator 100, this is not limited thereto and the present invention may also be applied to, for example, a quartz crystal oscillator. When the present invention is applied to a quartz crystal oscillator, a beam may be irradiated onto the frequency-adjusting metal film from outside the sealing member side on which the IC is not mounted. Specifically, the following configuration may be used.

[0081] First, we will explain the case of a crystal oscillator configured such that other electronic component elements (such as integrated circuit elements including oscillation circuits, capacitors, resistors, etc.) are mounted on the top surface of the above-mentioned triple-layered crystal resonator. In this case, before mounting the electronic component elements on the top surface of the crystal resonator, a beam is irradiated from above the crystal resonator onto a frequency-adjusting metal film formed on the main surface of the first sealing member facing the first excitation electrode, to perform frequency adjustment. Then, after mounting the electronic component elements on the top surface of the crystal resonator, a beam is irradiated from below the crystal resonator onto a frequency-adjusting metal film formed on the main surface of the second sealing member facing the second excitation electrode, to perform frequency adjustment.

[0082] Next, we will explain a crystal oscillator with a structure (single package structure) in which a crystal plate and electronic component elements are housed inside a base made of an insulating material such as ceramic, glass, or quartz and a lid is bonded to the base. In this case, after an electronic component element (e.g., an integrated circuit element) is mounted on the inner bottom surface of the base's recess, the crystal plate is bonded to a step in the recess so that it is positioned above the integrated circuit element. Then, a lid with a frequency-adjusting metal film formed on its main surface facing the crystal plate is bonded to the base so as to close the recess, and a beam is irradiated from the outside (above) of the lid to adjust the frequency.

[0083] In the above embodiment, a three-layer structure crystal unit 100 is used in which the crystal vibrating plate 10 is sandwiched between the first sealing member 20 and the second sealing member 30, but crystal units with other structures may also be used. Crystal units with structures other than the three-layer structure may, for example, be of the single package structure described above, or may be of a structure in which a frame is provided on each of the outer periphery edges of both main surfaces of the substrate (H-shaped package structure).

[0084] A single-package crystal unit 400 shown in Variation 4 of FIG. 13 includes, for example, a ceramic base 401, a silicon (Si) lid 402, a crystal vibration plate 410, and a frequency-adjusting metal film 420. The base 401 is formed in a generally rectangular parallelepiped shape with an opening at the top, and the lid 402 is bonded to the base 401 with a bonding material (e.g., AuSn) 403, thereby closing the opening of the base 401. The crystal vibration plate 410 is housed inside the base 401, and is connected to an electrode 404 formed on an inner bottom surface 401a of the base 401 by a conductive adhesive 405. First and second excitation electrodes 411 and 412 are formed on both main surfaces of the crystal vibration plate 410.

[0085] In such a crystal unit 400 having a single package structure, a frequency-adjusting metal film 420 is provided on an inner surface (a main surface facing the first excitation electrode 411) 402a of a lid 402 serving as a sealing member. The frequency-adjusting metal film 420 has a configuration similar to that of the frequency-adjusting metal films 26 and 36 of the above-described embodiments, and is configured to include a base metal layer and a metal layer thereon. A beam (e.g., a YAG laser) is irradiated onto the frequency-adjusting metal film 420 from the outside of the lid 402, and the beam passes through the inside of the lid 402 to heat the base metal layer of the frequency-adjusting metal film 420, thereby melting and vaporizing at least a portion of the metal layer of the frequency-adjusting metal film 420 and attaching it to the first excitation electrode 411, thereby enabling frequency adjustment similar to that of the above-described embodiment. Here, a doping layer made of, for example, B (boron) or P (phosphorus) may be formed on the inner surface 402a (the main surface facing the first excitation electrode 411) of the lid 402, in which case it is possible to provide a quartz crystal unit 400 with EMI countermeasures.

[0086] This application claims priority from Japanese Patent Application No. 2021-161534, filed on September 30, 2021, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0087] 10 Quartz crystal diaphragm (piezoelectric diaphragm) 20 First sealing member (sealing member) 30 Second sealing member (sealing member) 36 Frequency adjustment metal film 36a Undercoat metal layer 36b metal layer 100 Quartz crystal unit (piezoelectric vibration device) 111 1st excitation electrode 112 2nd excitation electrode 301 First main surface

Claims

1. A method for adjusting the frequency of a piezoelectric vibration device in which at least a vibration portion of a piezoelectric vibration plate having a vibration portion on which an excitation electrode is formed is airtightly sealed with a sealing member, comprising: a frequency-adjusting metal film made of a base metal layer and a metal layer laminated thereon is formed on a main surface of the sealing member facing the excitation electrode, the sealing member on which the frequency-adjusting metal film is formed is at least partially made of a light-transmitting material, the frequency adjustment metal film is formed smaller than the excitation electrode, and an outer periphery of the frequency adjustment metal film is located inside an outer periphery of the excitation electrode in a plan view, A method for adjusting the frequency of a piezoelectric vibration device, characterized in that a beam is irradiated onto the frequency adjustment metal film from outside the sealing member, the beam is transmitted through the inside of the sealing member to heat the underlying metal layer, thereby melting and evaporating at least a portion of the metal layer, and attaching it to the excitation electrode, thereby adjusting the frequency.

2. 2. The method for adjusting the frequency of a piezoelectric vibration device according to claim 1, A method for adjusting the frequency of a piezoelectric vibrating device, characterized in that the metal layer is melted by irradiating the beam without penetrating the underlying metal layer.

3. 3. The method for adjusting the frequency of a piezoelectric vibration device according to claim 1, A method for adjusting the frequency of a piezoelectric vibrating device, wherein the melting temperature of the underlying metal layer of the frequency adjusting metal film is higher than the melting temperature of the metal layer.

4. 4. The method for adjusting the frequency of a piezoelectric vibration device according to claim 3, A method for adjusting the frequency of a piezoelectric vibration device, wherein the difference between the melting temperature of the base metal layer and the melting temperature of the metal layer is 350 K or more.

5. 3. The method for adjusting the frequency of a piezoelectric vibration device according to claim 1, A method for adjusting the frequency of a piezoelectric vibration device, characterized in that the metal layer is composed of multiple metal layers, and the difference between the melting temperature of the underlying metal layer and the melting temperature of the uppermost metal layer is 350 K or more.

6. The method for adjusting the frequency of a piezoelectric vibration device according to any one of claims 1 to 5, A method for adjusting the frequency of a piezoelectric vibration device, characterized in that a first main surface of the sealing member on which the frequency-adjusting metal film is formed and a second main surface opposite to the first main surface are smooth surfaces.

7. 7. The method for adjusting the frequency of a piezoelectric vibration device according to claim 1, A method for adjusting the frequency of a piezoelectric vibration device, wherein the metal layer is formed from the same material as the excitation electrode.

8. The method for adjusting the frequency of a piezoelectric vibration device according to any one of claims 1 to 7, A method for adjusting the frequency of a piezoelectric vibration device, wherein the underlying metal layer is formed of titanium.

9. The method for adjusting the frequency of a piezoelectric vibration device according to any one of claims 1 to 8, A method for adjusting the frequency of a piezoelectric vibration device, wherein the beam is a visible light laser.

10. 10. The method for adjusting the frequency of a piezoelectric vibration device according to claim 1, A method for adjusting the frequency of a piezoelectric vibration device, wherein the space in which the vibration portion of the piezoelectric vibration plate is sealed is a vacuum.

11. The method for adjusting the frequency of a piezoelectric vibration device according to any one of claims 1 to 10, A method for adjusting the frequency of a piezoelectric vibration device, characterized in that the vertical distance between the excitation electrode and the frequency adjustment metal film is 2 to 200 μm.

12. The method for adjusting the frequency of a piezoelectric vibration device according to any one of claims 1 to 11, The piezoelectric vibration device is a first sealing member that covers a first main surface side of the vibration portion of the piezoelectric diaphragm, and a second sealing member that covers a second main surface side of the vibration portion of the piezoelectric diaphragm, the first sealing member and the piezoelectric diaphragm are joined together, and the second sealing member and the piezoelectric diaphragm are joined together, thereby hermetically sealing the vibration portion of the piezoelectric diaphragm; A method for adjusting the frequency of a piezoelectric vibration device, wherein the first sealing member and the second sealing member are made of quartz crystal.

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