Piezoelectric vibration device and method for manufacturing piezoelectric vibration device

Abstract

This piezoelectric vibration device has a vibration unit and a package that seals the vibration unit. The vibration unit has an excitation electrode and a portion in a piezoelectric body overlapping the excitation electrode. The package has a first substrate, a second substrate, and one or more capacitive elements. The first substrate opposes the vibration unit across a space. The second substrate opposes the vibration unit across a space, from a side opposite to the side of the first substrate. The one or more capacitive elements are positioned on a first surface of the first substrate facing the side opposite from the vibration unit. In a planar perspective view through the first surface, the capacitive elements are all misaligned from the excitation electrode.

Description

Piezoelectric vibration device and method for manufacturing the same

[0001] The present disclosure relates to a piezoelectric vibration device and a method for manufacturing the same.

[0002] A known example of a piezoelectric vibration device is a quartz crystal unit (see, for example, Patent Documents 1 and 2 below). A quartz crystal unit has a vibration element and a package that seals the vibration element. The vibration element has a quartz crystal blank and an excitation electrode that overlaps the quartz crystal blank. The quartz crystal blank vibrates when an AC voltage is applied to the quartz crystal blank via the terminals of the package and the excitation electrode. This vibration is used to generate an oscillation signal.

[0003] Japanese Patent Application Laid-Open No. 2006-129999 proposes providing a plurality of capacitance elements on the underside of a package. The capacitance elements are connected in parallel to one another so as to electrically connect a signal terminal and a reference potential terminal. The capacitance elements are arranged in a central region of the package.

[0004] Patent Document 2 discloses a quartz crystal unit constructed by stacking three substrate layers. The central layer functions as a quartz crystal blank in a plan view, and the outer peripheral portion functions as part of the package.

[0005] JP 2007-28271 A International Publication No. 2023 / 054200

[0006] A piezoelectric vibration device according to one aspect of the present disclosure includes a vibration section and a package. The vibration section includes an excitation electrode and a portion of a piezoelectric body where the excitation electrode overlaps. The package seals the vibration section. The package includes a first base, a second base, and one or more capacitance elements. The first base faces the vibration section across a space. The second base faces the vibration section across a space from the side opposite the first base. The one or more capacitance elements are located on a first surface of the first base facing the side opposite the vibration section. In a planar perspective view of the first surface, all of the capacitance elements are offset from the excitation electrode.

[0007] A method for manufacturing a piezoelectric vibration device according to one aspect of the present disclosure includes laser processing of a conductor located on the first surface. The package before the laser processing has a signal terminal, a reference potential terminal, and the conductor. The signal terminal is located on the first surface and is electrically connected to the excitation electrode. The reference potential terminal is located on the first surface. The conductor electrically connects the signal terminal and the reference potential terminal and includes some or all of the electrodes of the one or more capacitive elements. The laser processing adjusts the capacitance between the signal terminal and the reference potential terminal by cutting the conductor. The laser processing is not performed on an area of ​​the first surface that overlaps with the excitation electrode in a planar perspective view.

[0008] 5. An exploded perspective view of a quartz crystal resonator according to an embodiment. An exploded perspective view of the quartz crystal resonator of FIG. 1, seen from a direction different from that of FIG. 1. A cross-sectional view taken along line III-III in FIG. 1. A circuit diagram of the quartz crystal resonator of FIG. 1. A plan perspective view of the quartz crystal resonator of FIG. 1, seen from the bottom side. An enlarged view of region VI in FIG. 5. A cross-sectional view taken along line VII-VII in FIG. 6. Cross-sectional views showing an example of a procedure for a manufacturing method of the quartz crystal resonator of FIG. 1. A cross-sectional view showing a continuation of FIG. 8.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic. Therefore, for example, the dimensional ratios in the drawings do not necessarily correspond to the actual ones. Furthermore, the dimensional ratios may not match between drawings. Certain shapes and / or dimensions may be exaggerated, and details may be omitted. However, the above does not deny that the actual shapes and / or dimensions may be as shown in the drawings, or that features of shapes and / or dimensions may be extracted from the drawings.

[0010] 1 and 2 are exploded perspective views showing the configuration of a quartz crystal resonator 1 (an example of a piezoelectric resonator device) according to an embodiment. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. In Fig. 1 and 2, hatching indicates the surface of a relatively thin layer (e.g., a metal layer (conductor layer)) (i.e., it does not indicate a cross section).

[0011] For convenience, the drawings are provided with a Cartesian coordinate system D1D2D3. In the following, unless otherwise specified, a plan view or a plan perspective view refers to a view in the D3 direction. Either direction of the vibrator 1 may be considered to be the upper side. However, for convenience, the +D3 side may be considered to be the upper side, and terms such as "upper surface" and "lower surface" may be used.

[0012] The quartz crystal resonator 1 (hereinafter sometimes simply referred to as "resonator 1") is an electronic component configured by stacking the three layers shown in FIGS. 1 and 2 on top of each other as shown in FIG. 3. When an AC voltage is applied to the resonator 1, a vibrating portion 9 inside the resonator 1 vibrates. This vibration is used, for example, to generate an oscillation signal. The oscillation signal is, for example, a signal whose signal level (e.g., voltage) oscillates at a constant frequency.

[0013] The vibrator 1 has the above three layers, which are, in order from the -D3 side, a first substrate 3 (an example of a first base, which can also be considered an example of a second base), an intermediate layer 7 (an example of a piezoelectric body), and a second substrate 5 (an example of a second base, which can also be considered an example of a first base). From another perspective, the vibrator 1 also has the above vibrating section 9 and a package 11 (reference number shown in FIG. 3) that seals the vibrating section 9.

[0014] The vibrating part 9 has an excited part 7a (reference numeral shown in FIG. 3) which is a part of the intermediate layer 7, and a first excitation electrode 13A and a second excitation electrode 13B (hereinafter, these may be referred to as "excitation electrodes 13" without distinction) located on the excited part 7a. The pair of excitation electrodes 13 are located on the front and back (the +D3 side and the -D3 side) of the plate-shaped excited part 7a. When an AC voltage is applied to the excited part 7a by the pair of excitation electrodes 13, the excited part 7a vibrates.

[0015] The package 11 is composed of a first substrate 3, a second substrate 5, and the outer periphery of the intermediate layer 7. The first substrate 3 faces the vibrating section 9 from the -D3 side via a space. The second substrate 5 faces the vibrating section 9 from the opposite side (+D3 side) to the first substrate 3 via a space.

[0016] The surface of the first substrate 3 on the -D3 side (the side opposite to the vibrating section 9) will be referred to as the first surface 3a. The surface of the second substrate 5 on the +D3 side (the side opposite to the vibrating section 9) will be referred to as the second surface 5a. At least one capacitive element 15 (multiple, more specifically, four in the example of FIG. 2) is located on at least one of the first surface 3a and the second surface 5a (only the first surface 3a in the illustrated example). The capacitive element 15 contributes to adjusting the electrical characteristics of the vibrator 1, for example, as will be described in detail later.

[0017] 6, the capacitance element 15 is shown in Fig. 2 as a schematic representation of the capacitance element 15 used in a circuit diagram, although the capacitance element 15 may actually be a parallel plate type capacitance element, as shown in the figure.

[0018] 5 is a planar perspective view of the first surface 3a, in which each capacitance element 15 is formed by a pair of comb-shaped electrodes 17, which are shown in schematic form.

[0019] As shown in this figure, in a planar perspective view, all of the capacitance elements 15 are offset from the excitation electrodes 13. That is, the overlap between the two is small, or they do not overlap at all. For example, none of the capacitance elements 15 overlaps with the excitation electrodes 13. Note that, for convenience, the following description may be given on the assumption that none of the capacitance elements 15 overlaps with the excitation electrodes 13, as in the illustrated example, unless otherwise specified.

[0020] In this way, various effects are achieved by displacing all the capacitance elements 15 from the excitation electrodes 13. Examples are shown below.

[0021] For example, the distance between the capacitance element 15 and the excitation electrode 13 is increased, thereby reducing the stray capacitance generated between them. As a result, for example, when the design of the capacitance element 15 is changed or the conduction state of the capacitance element 15 is adjusted as described below, the possibility of an unintended change in frequency occurring due to a change in the stray capacitance is reduced.

[0022] Furthermore, for example, when the frequency is adjusted by performing laser processing (described later) on the capacitance element 15, the probability that the laser light will also be irradiated onto the excitation electrode is reduced, thereby reducing the probability that an unintended change in frequency will occur.

[0023] Furthermore, for example, since the capacitance element 15 does not overlap the excitation electrode 13, it is easy to prevent the wiring 19 extending from the capacitance element 15 from overlapping the excitation electrode 13. As a result, for example, it is possible to reduce the stray capacitance between the wiring 19 and the excitation electrode 13, and to reduce the probability that the excitation electrode 13 will be irradiated with laser light when laser processing (described later) is performed on the wiring 19.

[0024] Note that the above-described examples of effects do not provide a basis for excluding from the vibrator 1 according to the embodiment, for example, a configuration in which a conductor (separate from the capacitive element 15 and the wiring 19) overlaps with the excitation electrode 13, or a configuration in which a conductor is located closer to the excitation electrode 13 than the capacitive element 15 and the wiring 19. Even if such a conductor is present, for example, the above-described effects can be achieved to some extent, and other effects can also be achieved.

[0025] The above is an overview of the embodiment. Below, the embodiment will be roughly described in the following order: 1. Overall structure of vibrator (Figs. 1 to 4) 1.1. General structure 1.2. Structure of the illustrated example 1.2.1. Outline and external terminals 1.2.2. Internal structure 1.2.3. Intermediate layer 1.2.4. First substrate and second substrate 1.3. Circuit configuration 2. Positional relationship between capacitance element and excitation electrode (Figs. 1 to 3 and 5) 2.1. General positional relationship 2.2. Positional relationship in the illustrated example 2.3. Other 3. Configuration of capacitance element 3.1. General configuration 3.2. Configuration in the illustrated example 3.2.1. Comb-tooth electrode (Fig. 6) 3.2.2. Cross-sectional structure (Fig. 7) 3.2.3. Processing area 4. Method of manufacturing vibrator (Figs. 8 and 9) 5. Summary of the embodiment

[0026] (1. Overall Structure of the Vibrator) (1.1. General Structure) The overall structure (structure) of the vibrator 1 (piezoelectric vibration device) may be any of a variety of known configurations, and is not limited to the configuration in which three layers of plate-like members are stacked, as illustrated in Figures 1 to 3. Furthermore, the piezoelectric vibration device may not simply be a vibrator, but may be a vibrator with a thermistor, or an oscillator having an IC (Integrated Circuit) that applies voltage to the vibrating portion 9 (from another perspective, having an oscillation circuit). Although not specifically illustrated, several examples are given below.

[0027] For example, the configuration of a piezoelectric vibration device may include a base (first base) having a recess on its top surface, a piezoelectric vibration element (an element including a vibration portion, the same applies below) mounted on the bottom surface of the recess by bumps (e.g., conductive resin), and a lid (second base) that covers the recess. Only the piezoelectric vibration element may be mounted in the recess, or other elements (e.g., a thermistor or IC, the same applies below) may also be mounted. In the latter case, one recess may be formed, or a further recess may be formed on the bottom surface of the recess. The lid may be an insulator or a conductor such as metal.

[0028] Furthermore, for example, the piezoelectric vibration device may be configured to include a substrate (first base), a piezoelectric vibration element mounted on the upper surface of the substrate by bumps, and a cap (second base) placed on the upper surface of the substrate to cover the piezoelectric vibration element. Only the piezoelectric vibration element may be mounted in the cap, or other elements may also be mounted. The cap may be an insulator or a conductor such as metal.

[0029] Furthermore, for example, the piezoelectric vibration device may be configured to include a base (first base) having recesses on both the top and bottom surfaces (or, from another perspective, an H-shaped cross section), a piezoelectric vibration element mounted on the bottom surface of the recess on the top surface, a cover (second base) that covers the recess on the top surface, and another element mounted in the recess on the bottom surface. The surface (first surface) on which the capacitive element is provided may be the bottom end surface of a wall surrounding the recess on the bottom surface, or the bottom surface of the recess on the bottom surface. The H-shaped base may be configured as an integral unit, or the base having the recess on its top surface may be mounted so as to cover an opening in the circuit board (which becomes the recess on the bottom surface).

[0030] Furthermore, the piezoelectric vibration device may have a thermostatic chamber surrounding the piezoelectric vibrator or piezoelectric oscillator. However, in the case of a piezoelectric vibration device having a thermostatic chamber, only a part of the piezoelectric vibration device may be regarded as a piezoelectric vibration device.

[0031] As will be described later, the illustrated piezoelectric vibrating device is a surface-mount type and has layered external terminals, although the external terminals may be pins for through-hole mounting or pins for surface mounting.

[0032] (1.2. Structure of the illustrated example) The structure illustrated in Figures 1 to 3 will be described below. Note that the explanation of the illustrated example (including explanations other than those in this section) may be applied to the other structures described above, provided that no contradictions arise. Furthermore, various specific configurations are possible for the vibrator 1 having a structure in which three layers of plate-like members are stacked, and the illustrated example is merely one example.

[0033] (1.2.1. External Shape and External Terminals) The external shape of the vibrator 1 is roughly a thin rectangular parallelepiped (the length in the D3 direction is shorter than the lengths in other directions). The shape in plan view is a rectangle with the D1 direction as the longitudinal direction. Note that when referring to a rectangular shape (or rectangle), the corners may be chamfered. The same applies to other members and other polygons.

[0034] The dimensions of the vibrator 1 are arbitrary. Examples of relatively small dimensions of the vibrator 1 are shown below. In a plan view, the maximum length in the longitudinal direction (e.g., the length of the long side) and the maximum length in the lateral direction (e.g., the length of the short side) are, for example, 0.5 mm or more and 2 mm or less. The thickness (D3 direction) is, for example, 0.1 mm or more and 0.3 mm or less.

[0035] As mentioned above, the vibrator 1 is a surface-mount type, and as shown in FIG. 2, has a plurality of (four in the illustrated example) pad-shaped (layer-shaped) external terminals 21 (21S1, 21S2, 21G1, and 21G2) overlapping the first surface 3a.

[0036] The four external terminals 21 include a first signal terminal 21S1 electrically connected to the first excitation electrode 13A and a second signal terminal 21S2 electrically connected to the second excitation electrode 13B (hereinafter, these terminals may be referred to as "signal terminals 21S" without distinction). A fluctuating potential having a waveform with the same amplitude but opposite phase is input to the two signal terminals 21S from, for example, an external source (e.g., a circuit board on which the vibrator 1 is mounted; the same applies hereinafter). This applies an AC voltage to the two excitation electrodes 13.

[0037] The four external terminals 21 include a first GND terminal 21G1 and a second GND terminal 21G2 (hereinafter, these may be referred to as "GND terminals 21G" without distinguishing between them) to which a reference potential is applied from the outside. At least one of the two GND terminals 21G (only the first GND terminal 21G1 in the illustrated example) is connected to the capacitive element 15. Note that the GND terminal 21G to which the capacitive element 15 is not connected (the second GND terminal 21G2 in the illustrated example) may be electrically floating without being applied with a reference potential.

[0038] The external terminals 21 may be positioned arbitrarily. For example, a pair of signal terminals 21S are located at a pair of diagonal corners of the rectangular first surface 3a. A pair of GND terminals 21G are located at another pair of diagonal corners of the first surface 3a. In other words, the multiple external terminals 21 are arranged along the outer edge of the first surface 3a. The signal terminals 21S and the GND terminals 21G are adjacent to each other in a direction along the outer edge of the first surface 3a (with no other terminals interposed therebetween). Note that, when referring to the positions of the external terminals 21 as described above, the edge of the external terminal 21 on the outer edge side of the first surface 3a may coincide with the outer edge of the first surface 3a or may be slightly spaced inward from the outer edge of the first surface 3a.

[0039] The shape, dimensions, and material of the external terminals 21 are also arbitrary. For example, the planar shape of the external terminals 21 is a rectangle having four sides parallel to the four sides of the first surface 3a and a longitudinal direction parallel to the longitudinal direction of the first surface 3a. Although not particularly shown, one external terminal 21 may have a large chamfered corner on the central side of the first surface 3a to specify the orientation of the vibrator 1. The length of each side of the external terminal 21 may be greater than (in the illustrated example), equal to, or smaller than one-third of the length of one side of the first surface 3a parallel to each side. The thickness of the external terminals 21 is also arbitrary. The material of the external terminals 21 may be metal, and may be composed of only one layer or two or more layers.

[0040] Unlike the illustrated example, the number of external terminals 21 may be less than or more than four. For example, only two external terminals 21, one signal terminal 21S and one GND terminal 21G, may be provided. A reference potential may be input to one excitation electrode 13, and a variable potential may be input to the other excitation electrode 13, thereby applying an AC voltage to the excited portion 7 a.

[0041] Furthermore, for example, the plurality of external terminals 21 (four or less or more than four) may include external terminals 21 for the aforementioned thermistors or ICs. The external terminals 21 may be provided on the second surface 5a instead of or in addition to the first surface 3a. The external terminals 21 may be located toward the center of the first surface 3a or the second surface 5a to the extent that they are not considered to be located in corners. The vibrator 1 may have castellations with metallized inner surfaces at corners and / or side surfaces.

[0042] (1.2.2. Internal Structure) The intermediate layer 7 is composed of a generally plate-shaped piezoelectric body, and has an element component 7e and a frame portion 7f surrounding the element component 7e in a planar view. The element component 7e has the excited portion 7a described above. A combination of the element component 7e and various conductors (including the excitation electrode 13) located on the element component 7e is sometimes referred to as a vibration element 23 (corresponding to the piezoelectric vibration element described above). The frame portion 7f is sandwiched between the first substrate 3 and the second substrate 5, and together with these substrates, forms a space in which the vibration element 23 is housed. The space is hermetically sealed. The space may be filled with, for example, an appropriate gas (e.g., an inert gas), or may be a vacuum.

[0043] The element component 7e is separated from the frame portion 7f along its entire periphery. The vibration element 23 is supported by the package 11 by being bonded to at least one of the +D3 side surface of the first substrate 3 and the −D3 side surface of the second substrate 5 (only the former in the illustrated example). Unlike the illustrated example, the vibration element 23 may be supported by connecting the element component 7e and the frame portion 7f at least along a part of the outer periphery of the element component 7e (see, for example, Patent Document 2).

[0044] The vibration element 23 is supported in a cantilevered manner by being joined at one end in a predetermined direction in a plan view to the first substrate 3 and / or the second substrate 5 (only the former in the illustrated example). Unlike the illustrated example, the vibration element 23 may be supported at both ends in the predetermined direction, or may be supported around the entire outer periphery.

[0045] The wiring path for electrically connecting the excitation electrode 13 and the signal terminal 21S is arbitrary. In the illustrated example, it is as follows.

[0046] The vibration element 23 has an extraction electrode 25 extending from the excitation electrode 13. The extraction electrode 25 extending from the first excitation electrode 13A located on the -D3 side surface of the element component 7e is located entirely on the -D3 side surface of the element component 7e. The extraction electrode 25 extending from the second excitation electrode 13B located on the +D3 side surface of the element component 7e is located on the +D3 side surface of the element component 7e and reaches the -D3 side surface of the element component 7e via a through hole 7h that penetrates the element component 7e in the D3 direction. Note that the extraction electrode 25 may extend to both the front and back of the element component 7e via the side surface of the element component 7e instead of or in addition to the through hole 7h. The vibration element 23 is electrically connected to the wiring of the package 11 by joining a pair of extraction electrodes 25 to wiring 27 (FIGS. 1 and 3) located on the +D3 side surface of the first substrate 3.

[0047] The wiring 27 extends from the position where it is joined to the extraction electrode 25 to directly above the signal terminal 21S. It is electrically connected to the signal terminal 21S via a through conductor 29 that penetrates the first substrate 3. For convenience, the upper or lower end of the through conductor 29 is shown by a solid line in Figures 1 and 2. In reality, the upper or lower end of the through conductor 29 may be covered by the wiring 27 or the signal terminal 21S (however, it may be as shown in the figures).

[0048] In FIG. 1 , the wiring 27 on the -D2 side (the wiring 27 connected to the second signal terminal 21S2) has a portion that extends toward the opposite side (the -D1 side) from the through conductor 29. This portion, together with, for example, the auxiliary wiring 31 described below, contributes to strengthening the bond between the frame portion 7f and the second substrate 5. As shown in FIGS. 2 and 3 , the auxiliary wiring 31 that is bonded opposite to the wiring 27 is provided on the -D3 side surface of the second substrate 5 (although it does not have to be provided). The auxiliary wiring 31 is, for example, bonded overlapping the wiring 27, and contributes to strengthening the bond between the frame portion 7f and the second substrate 5 and reducing the resistance value from the lead electrode 25 to the signal terminal 21S.

[0049] Unlike the illustrated example, for example, at least one of the extraction electrodes 25 may include a portion located on the +D3 side surface of the element component 7e and be connected to wiring located on the −D3 side surface of the second substrate 5. Then, for example, an electrical path from the wiring may reach the signal terminal 21S by way of a through conductor that penetrates the intermediate layer 7 and a through conductor that penetrates the first substrate 3. Alternatively, an electrical path from the wiring may reach the signal terminal 21S by way of a through conductor that penetrates the second substrate 5, a conductor layer located on the +D3 side surface of the second substrate 5, another through conductor that penetrates the second substrate 5, a through conductor that penetrates the intermediate layer 7, and a through conductor that penetrates the first substrate 3 (see, for example, Patent Document 2).

[0050] Furthermore, unlike the illustrated example, a solid electrode including the excitation electrode 13 and the extraction electrode 25 may be formed on the entire surface of the −D3 side of the element component 7e. The extraction electrode 25 on the +D3 side of the element component 7e may be connected to wiring located on the −D3 side surface of the second substrate 5, and the solid electrode may be connected to wiring located on the +D3 side surface of the first substrate 3. The subsequent path to the signal terminal 21S is easily inferable from the above explanation and will not be described here. In such an embodiment, the portion of the solid electrode facing the +D3 side excitation electrode 13 may be considered the −D3 side excitation electrode 13. The relationship between the solid electrode and the D3 direction (the side on which the external terminal 21 is located) may be reversed.

[0051] Conductors such as the excitation electrode 13, comb-tooth electrode 17, wiring 19, external terminal 21, extraction electrode 25, wiring 27, and through conductor 29 are made of, for example, metal. The specific type of metal is arbitrary. A conductor layer (e.g., 13, 17, 19, 21, 25, or 27) may be made of only one layer, or may be made of two or more layers. Conductor layers located on the same side of a single plate-like member (first substrate 3, second substrate 5, or intermediate layer 7) may be made of the same material and have the same thickness throughout, or may have different materials and / or thicknesses in some parts.

[0052] The bonding mode between the first substrate 3 and the intermediate layer 7, and the bonding mode between the intermediate layer 7 and the second substrate 5 may be various. In the illustrated example, the first substrate 3 and the intermediate layer 7 are bonded to each other by bonding metal layers (reference numerals omitted) provided along the peripheries of both substrates. Similarly, the intermediate layer 7 and the second substrate 5 are bonded to each other by bonding metal layers (reference numerals omitted) provided along the peripheries of both substrates. Unlike the illustrated example, the two members may be bonded to each other via an insulating layer or by direct bonding. Furthermore, bonding may be performed at any position and over any width, in addition to the periphery.

[0053] (1.2.3. Intermediate Layer) The intermediate layer 7 is, for example, entirely made of the same (single) material (piezoelectric body) and has a constant thickness over its entire surface. Unlike the description of the embodiment, for example, a portion of the intermediate layer 7 may have a different thickness than other portions. Furthermore, for example, the intermediate layer 7 may be made by stacking two or more layers made of different materials. In this case, for example, all or a portion of the multiple layers may be located on both the excited portion 7a (and / or the element component 7e) and the frame portion 7f.

[0054] The intermediate layer 7 is, for example, an AT-cut quartz crystal piece. The vibrating portion 9 utilizes, for example, thickness-shear vibration. In this case, the vibrating element 23 and the excitation electrode 13 may have any shape.

[0055] For example, the element component 7e may be flat and have a constant thickness throughout (as shown in the example), or may be a so-called mesa or inverted mesa shape. The planar shape of the element component 7e may be rectangular (as shown in the example), circular, or elliptical. The planar shape of the excitation electrode 13 may be rectangular, circular (as shown in the example), or elliptical. The planar shapes of the element component 7e and the excitation electrode 13 may be different (as shown in the example), or similar. The relative relationship between the longitudinal direction of the element component 7e, the longitudinal direction of the excitation electrode 13, and the longitudinal direction of the intermediate layer 7 may also be arbitrary.

[0056] Unlike the above, the vibration used by the vibrating portion 9 may be other than thickness-shear vibration (for example, thickness-extensional vibration, expansion vibration, length vibration, bending vibration, torsional vibration, contour-shear vibration, or elastic wave). As can be understood from this, the material of the piezoelectric body may be other than an AT-cut quartz crystal piece, and the shapes of the excited portion 7a (element component 7e) and the excitation electrode 13 may be various.

[0057] For example, the vibration element 23 may be of a tuning fork type. In this case, the excitation electrode 13 may be formed not only on the front and back surfaces of the excited portion 7a but also on the side surfaces. Also, for example, the excitation electrode 13 may be a comb-shaped electrode that generates elastic waves. The piezoelectric body may be a single crystal of lithium tantalate, a single crystal of lithium niobate, or a polycrystal containing appropriate components. The cut angles of various single crystals are arbitrary. The cut angle of quartz crystal that utilizes thickness-shear vibration may be SC cut or BT cut.

[0058] The position and dimensional ratio of the vibration unit 9 (or the vibration element 23) relative to the intermediate layer 7 (or, from another perspective, the package 11) are also arbitrary. For example, the length of the vibration element 23 in the D1 direction (the maximum length if the vibration element 23 is not rectangular; the same applies hereinafter in this paragraph) may be less than half (in the illustrated example) or more than half of the length of the intermediate layer 7 in the D1 direction. The length of the vibration element 23 in the D2 direction may be less than half (in the illustrated example) or more than half of the length of the intermediate layer 7 in the D2 direction. For example, the vibration unit 9 and / or the vibration element 23 may be positioned toward the end of the intermediate layer 7 in the D1 direction (in the illustrated example), or may be positioned at the center of the intermediate layer 7. For example, the vibration unit 9 and / or the vibration element 23 may be positioned toward the end of the intermediate layer 7 in the D2 direction, or may be positioned at the center of the intermediate layer 7 (in the illustrated example). In this paragraph, the D1 direction can be rephrased as, for example, the longitudinal direction of the intermediate layer 7.

[0059] The thickness of the excited portion 7a that utilizes thickness-shear vibration is set according to the intended frequency. Specifically, the thinner the excited portion 7a, the higher the resonant frequency. According to the manufacturing method described below, the excited portion 7a can be made relatively thin. Therefore, the vibrating portion 9 may be intended for use at relatively high frequencies. For example, the excited portion 7a, the element component 7e, and / or the intermediate layer 7 may be 1 μm or more and 100 μm or less. Note that such thicknesses may also be applied to modes that utilize vibrations other than thickness-shear vibration.

[0060] The planar shape of the outer edge of the frame portion 7f is basically the same as the planar shape of the package 11, for example. The planar shape of the inner edge of the frame portion 7f may be similar to the planar shape of the outer edge of the element component 7e (as in the illustrated example), or may be completely different. In the illustrated example, the inner edge of the frame portion 7f forms a slit of a certain width between it and the outer edge of the element component 7e. Unlike the illustrated example, the gap between the element component 7e and the frame portion 7f may have a shape and / or width that cannot be considered a slit.

[0061] (1.2.4. First Substrate and Second Substrate) The first substrate 3 is, for example, a flat plate-like member with a substantially constant thickness. The first substrate 3 may have a recess 3r (FIGS. 1 and 3) in a region facing the vibration section 9. In a planar perspective view, the recess 3r overlaps the entire vibration section 9. Furthermore, the recess 3r does not overlap the end (edge) of the vibration element 23 on the side where the extraction electrode 25 is extracted. This reduces the likelihood that the vibration section 9 will come into contact with the first substrate 3 in the vibration element 23 that is bonded to the upper surface of the first substrate 3 outside the recess 3r.

[0062] Unlike the illustrated example, for example, the recess 3r may not be provided, and the clearance between the vibrating section 9 and the first substrate 3 may be ensured only by a metal layer interposed between the intermediate layer 7 and the first substrate 3 and bonding them together. Also, in a plan view, the edge of the vibrating element 23 on the side different from the side from which the extraction electrode 25 is extracted (the +D1 side, the -D2 side, or the +D2 side) may be located inside, coincident with, or outside the edge of the recess 3r. The planar shape, cross-sectional shape, depth, etc. of the recess 3r are arbitrary.

[0063] The second substrate 5 is, for example, a flat member having a substantially uniform thickness. The second substrate 5 may have a recess 5r ( FIGS. 2 and 3 ) in a region facing the vibration section 9. In a planar perspective view, the recess 5r overlaps the entire vibration section 9. This reduces the likelihood that the vibration section 9 will come into contact with the second substrate 5. In the illustrated example, the extraction electrode 25 is not bonded to the second substrate 5, so the recess 5r may overlap the entire vibration element 23. However, in a mode in which the extraction electrode 25 is bonded to the second substrate 5, the recess 5r may not overlap the end (edge) of the vibration element 23 from which the extraction electrode 25 is extracted, as with the first substrate 3.

[0064] Unlike the illustrated example, for example, the recess 5r may not be provided, and the clearance between the vibrating section 9 and the second substrate 5 may be ensured only by a metal layer interposed between the intermediate layer 7 and the second substrate 5 and bonding them together. Also, in a plan view, the edges of the vibrating element 23 in various directions (-D1 side, +D1 side, -D2 side, or +D2 side) may be located inside, coincident with, or outside the edges of the recess 5r. The planar shape, cross-sectional shape, depth, etc. of the recess 5r are arbitrary.

[0065] The thickness of the first substrate 3 and the second substrate 5 is arbitrary. For example, the thickness of each substrate may be greater than the thickness of the intermediate layer 7. The thickness of the first substrate 3 and the second substrate 5 may be the same as or different from each other. The thickness of each substrate may be, for example, 50 μm or more and 200 μm or less, or 50 μm or more and 100 μm or less.

[0066] The materials of the first substrate 3 and the second substrate 5 are also arbitrary. For example, each substrate may be integrally formed of a single material, or may be formed by laminating different materials. In each substrate, the material of all or part of the layers may be, for example, an insulator or a semiconductor (e.g., an intrinsic semiconductor). The insulator may be an inorganic material (e.g., quartz or ceramic) or an organic material (e.g., resin). Examples of semiconductors include silicon (Si) and germanium (Ge).

[0067] (1.3. Circuit Configuration) FIG. 4 is a circuit diagram showing the electrical configuration of the vibrator 1.

[0068] The first signal terminal 21S1 and the first excitation electrode 13A are electrically connected. The second signal terminal 21S2 and the second excitation electrode 13B are electrically connected. One or more (four in the illustrated example) capacitance elements 15 electrically connect the first signal terminal 21S1 and the first GND terminal 21G1. The multiple capacitance elements 15 are connected in parallel, for example. However, some or all of the multiple capacitance elements 15 may be connected in series. Although not particularly illustrated, the second GND terminal 21G2 may be electrically connected to the first GND terminal 21G1 by a conductor within the package 11 or an external conductor (it does not have to be connected).

[0069] As shown in the illustrated example, one or more capacitance elements 15 connecting the excitation electrode 13 and the reference potential portion (GND terminal 21G) contribute to adjusting the frequency of the oscillation signal by adjusting their capacitance, as is well known. The capacitance adjustment may be performed, for example, by increasing or decreasing the number of capacitance elements 15 and / or by adjusting the capacitance of each capacitance element 15 (i.e., adjustment at the design stage). Furthermore, since the capacitance elements 15 (and wiring 19) are located outside the package 11, the capacitance can also be adjusted by laser processing after sealing the vibration element 23, as described below.

[0070] Unlike the illustrated example, instead of or in addition to the capacitance element 15 between the first signal terminal 21S1 and the first GND terminal 21G1, a capacitance element 15 may be provided between the second signal terminal 21S2 and the second GND terminal 21G2, between the first signal terminal 21S1 and the second GND terminal 21G2, and / or between the second signal terminal 21S2 and the first GND terminal 21G1.

[0071] From another perspective, the excitation electrode 13 to which the capacitance element 15 is electrically connected may be the first excitation electrode 13A on the side where the capacitance element 15 is located (the side of the first substrate 3), or the second excitation electrode 13B on the side opposite to the side where the capacitance element 15 is located (the side of the second substrate 5), or both. From yet another perspective, one signal terminal 21S and one GND terminal 21G connected to each other by one capacitance element 15 may be aligned along the short side of the first surface 3a (in the illustrated example), or may be aligned along the long side of the first surface 3a.

[0072] (2. Positional Relationship Between Capacitive Elements and Excitation Electrodes) (2.1. General Positional Relationship) As already mentioned with reference to Figure 5, in a planar perspective view of the first surface 3a, none of the capacitive elements 15 overlaps, for example, the excitation electrodes 13. Such a positional relationship can be realized in various ways. For example, as follows. In the following description, for convenience, expressions may be used assuming a planar perspective view of the first surface 3a unless otherwise specified.

[0073] First, consider a configuration in which the capacitance element 15 and the excitation electrode 13 overlap, which is the opposite of the embodiment. A typical example of this configuration is a configuration in which both the excitation electrode 13 and the capacitance element 15 are located at the center of the first surface 3a. The configuration in which the excitation electrode 13 is located at the center of the first surface 3a is a common configuration. Furthermore, since the external terminals 21 are generally located at at least four corners, it is easy to ensure an area for arranging the capacitance element 15 in the center of the first surface 3a. In other words, the configuration in which the capacitance element 15 and the excitation electrode 13 overlap is a natural configuration.

[0074] The change from the above-described embodiment to an embodiment in which the capacitance element 15 and the excitation electrode 13 do not overlap may be realized, for example, by bringing the capacitance element 15 closer to the outer edge of the first surface 3 a, by bringing the excitation electrode 13 closer to the outer edge of the first surface 3 a, or by bringing the both closer to edges (e.g., one side) in different directions (e.g., opposite directions) (example shown in the figure). From another perspective, either the capacitance element 15 or the excitation electrode 13 (or the vibration element 23 from another perspective) may be shifted from its typical position.

[0075] The direction in which the capacitance element 15 and / or the excitation electrode 13 are shifted from the center of the first surface 3 a may be either the longitudinal direction (D1 direction) of the first surface 3 a or the lateral direction (D2 direction) of the first surface 3 a, or may be inclined toward these directions. Furthermore, in an embodiment in which both the capacitance element 15 and the excitation electrode 13 are shifted in different directions from the center of the first surface 3 a, the different directions may be opposite to each other or may be directions intersecting (for example, perpendicular to) each other.

[0076] For example, all of the multiple capacitance elements 15 may be located on the same side (for example, the −D1 side, the +D1 side, the −D2 side, or the +D2 side) with respect to the excitation electrode 13. Furthermore, some of the multiple capacitance elements 15 may be located on different sides with respect to the excitation electrode 13. For example, some may be located on the +D1 side with respect to the excitation electrode 13, and the other may be located on the −D1 side, the −D2 side, or the +D2 side.

[0077] As already described, unlike the illustrated example, the capacitance element 15 may be provided on the second surface 5a instead of the first surface 3a. In this case, the positional relationship between the capacitance element 15 and the excitation electrode 13 described above (or described later) (hereinafter, sometimes referred to as the "first positional relationship") may naturally be established. Furthermore, the capacitance element 15 may be provided on both the first surface 3a and the second surface 5a. In this case, the first positional relationship may be established only with respect to the first surface 3a, only with respect to the second surface 5a, or with respect to both surfaces.

[0078] In the illustrated example, the outer edges of the two excitation electrodes 13 coincide with each other in a planar perspective view. Therefore, it is not necessary to distinguish between the two excitation electrodes 13 when determining whether the first positional relationship is established. Unlike the illustrated example, in a configuration in which the outlines of two or more excitation electrodes 13 do not coincide with each other in a planar perspective view, the first positional relationship may be established for only one excitation electrode. However, for example, the first positional relationship may be established for all excitation electrodes. Furthermore, for example, when the first surface 3a is the object of determination, the first positional relationship may be established for at least the first excitation electrode 13A. In other words, the first positional relationship may be established for the excitation electrode closest to the surface to be determined and / or the excitation electrode on the side of the excited portion 7a on the surface to be determined.

[0079] The above description has been based on the premise that none of the capacitance elements 15 (on the first surface 3 a and / or the second surface 3 b) overlaps with the excitation electrodes 13. However, it is clear that the effects described in the description of the embodiment are achieved even when the capacitance elements 15 and the excitation electrodes 13 overlap slightly. Therefore, as described in the description of the outline of the embodiment, all of the capacitance elements 15 may simply be shifted from the excitation electrodes 13.

[0080] Whether or not the capacitance element 15 is misaligned with respect to the excitation electrode 13 may be determined rationally. An example is shown below. When a large portion (e.g., 80% or more) of the area of ​​the capacitance element 15 does not overlap with the excitation electrode 13, and a large portion (e.g., 80% or more) of the area of ​​the excitation electrode 13 does not overlap with the capacitance element 15, the capacitance element 15 may be considered to be misaligned with the excitation electrode 13. Note that the area of ​​each capacitance element 15 may be determined based on the area of ​​the smallest possible convex polygon that encompasses all the electrodes of each capacitance element 15 (i.e., the gap between the electrodes may be included in the calculation). Note that even when the excitation electrode 13 has a gap, the area may be determined in the same manner as above.

[0081] Here, the positional relationship of the capacitance element 15 with respect to the excitation electrode 13 has been described. The description of the positional relationship of the capacitance element 15 with respect to the excitation electrode 13 may be applied to the wiring 19, or may be applied to both the capacitance element 15 and the wiring 19, unless a contradiction or the like occurs. Therefore, for example, in the description of the embodiments, the term "capacitance element 15" may be replaced with the term "capacitance element 15 and / or wiring 19" unless a contradiction or the like occurs.

[0082] (2.2. Positional Relationship in the Example Shown) In the example shown in FIG. 5, the capacitive element 15 and the excitation electrode 13 are positioned on opposite sides in the direction D1 and do not overlap each other.

[0083] More specifically, all (four) capacitive elements 15 are contained in an area (hereinafter sometimes referred to as an “inter-terminal area”) sandwiched between the first signal terminal 21S1 and the first GND terminal 21G1 to which the capacitive elements 15 are connected. The arrangement direction of the multiple capacitive elements 15 is a direction intersecting (orthogonal to) the arrangement direction of the first signal terminal 21S1 and the first GND terminal 21G1.

[0084] Furthermore, the excitation electrode 13 is contained in an area (inter-terminal area) sandwiched between the second signal terminal 21S2 and the second GND terminal 21G2 to which the capacitive element 15 is not connected. From another perspective, the excitation electrode 13 does not overlap any of the external terminals 21. However, even in this case, there may be an overlap of an error level (for example, 2% or less of the area of ​​the excitation electrode 13).

[0085] Unlike the illustrated example, only a portion of the multiple capacitance elements 15 may be located in the inter-terminal region. In other words, at least one capacitance element 15 may be located in the inter-terminal region. Furthermore, the portion may be, for example, 80% or more of the total area of ​​the multiple capacitance elements 15 (the area of ​​each capacitance element 15 is as described above). Furthermore, only a portion of the excitation electrode 13 may be located in the inter-terminal region. The portion may be, for example, 80% or more of the area of ​​the excitation electrode 13. Just to be clear, not all of the multiple capacitance elements 15 and / or all of the excitation electrodes 13 need to be located in the inter-terminal region.

[0086] From a different perspective from the inter-terminal region, in the illustrated example, all of the capacitance elements 15 are located in a region on one side of the center (geometric center) of the first surface 3a in a predetermined direction (direction D1). Furthermore, the excitation electrode 13 is located in a region on the other side of the center of the first surface 3a in the predetermined direction. That is, the two are located in different regions when the first surface 3a is divided into two equal parts. Although not specifically illustrated, the two may be located in regions on both sides when the first surface 3a is divided into three equal parts.

[0087] The distance between the capacitance element 15 (closest to the excitation electrode 13) and the excitation electrode 13 (the shortest distance in this paragraph) is arbitrary. For example, the distance may be 1 / 10 or more, 1 / 5 or more, or 1 / 3 or more of the length of the first surface 3a in the D1 direction (the direction in which the capacitance element 15 and the excitation electrode 13 are arranged), or may be less than 1 / 10, 1 / 5, or 1 / 3. The above lower and upper limits may be combined so as not to cause a contradiction. Furthermore, as can be understood from the above description, the distance between the capacitance element 15 and the excitation electrode 13 may be longer (in the illustrated example), equal to, or shorter than the distance between the external terminals 21 in the D1 direction.

[0088] (2.3. Others) The specific value of the total area of ​​the multiple capacitance elements 15 (the area of ​​each capacitance element 15 has already been described) or the area of ​​the smallest convex polygon that encompasses the multiple capacitance elements 15 is arbitrary. For example, these areas may be less than 1 / 10 of the area of ​​the first surface 3a, or may be 1 / 10 or more. Furthermore, these areas may be larger than (in the illustrated example), equal to, or smaller than the area of ​​the excitation electrode 13. Furthermore, the area of ​​the excitation electrode 13 is arbitrary. For example, the area of ​​the excitation electrode 13 may be less than 1 / 20 of the area of ​​the first surface 3a, or may be 1 / 20 or more of the area of ​​the first surface 3a.

[0089] As described above, the capacitance element 15 is located on the first surface 3a. In this regard, the capacitance element 15 may be directly overlapped with the first surface 3a, or may be overlapped with the first surface 3a via a thin film (for example, a thin film that is sufficiently thinner than the thickness of the first substrate 3 (for example, 1 / 20 or less) and / or a thin film that is thinner than the thickness of the capacitance element 15). However, the surface of the thin film may be considered as part or all of the first surface 3a.

[0090] (3. Configuration of Capacitive Element) (3.1. General Configuration) The configuration of the capacitive element 15 is arbitrary. For example, the capacitive element 15 may be a parallel plate type, or may have comb-tooth electrodes 17 as described below. Although not particularly shown, the parallel plate type capacitive elements 15 may face each other in a direction along the first surface 3a, or may face each other in a normal direction of the first surface 3a with a dielectric layer interposed therebetween. The capacitance of the capacitive element 15 may be set appropriately depending on the amount of frequency adjustment.

[0091] (3.2. Configuration of the illustrated example) (3.2.1. Comb-tooth electrode) FIG. 6 is a plan view showing an example of the configuration of the capacitance element 15. This figure corresponds to an enlarged view of region VI in FIG. 5. FIG. 6 is a figure that is closer to the actual configuration than FIG. 5. In FIG. 6, the protective film 35, which will be described later, is not shown. Also, in FIG. 6, for convenience, the surface (i.e., the surface that is not a cross section) of the dielectric layer 33, which will be described later, is hatched with diagonal lines.

[0092] The capacitance element 15 has a pair of interdigitated comb electrodes 17. Each interdigitated comb electrode 17 has a bus bar 17a and a plurality of electrode fingers 17b extending in parallel from the bus bar 17a. The capacitance of the capacitance element 15 is determined by, for example, the number, length, thickness, and spacing of the plurality of electrode fingers 17b, as well as the dielectric constant of the surroundings. In other words, these design parameters may be set as appropriate.

[0093] In the illustrated example, the capacitance element 15 is arranged so that the opposing direction of the pair of bus bars 17a coincides with the opposing direction of the first signal terminal 21S1 and the first GND terminal 21G1 (direction D2). Unlike the illustrated example, for example, the capacitance element 15 may be arranged so that the opposing direction of the pair of bus bars 17a coincides with direction D1.

[0094] The capacitances of the multiple capacitive elements 15 may be the same or different from each other. From another perspective, the configurations (including dimensions, etc.) of the multiple capacitive elements 15 may be the same or different from each other. In the latter embodiment, the difference and / or ratio of capacitances is arbitrary, and the design items (as described above) that are set differently from each other are also arbitrary. Furthermore, the electrode fingers 17 b adjacent to each other between adjacent capacitive elements 15 may or may not function as capacitive elements. In other words, the distance between them is arbitrary.

[0095] The connection position of the wiring 19 to the bus bar 17a is arbitrary. For example, the wiring 19 may be connected to the end of the bus bar 17a (the end of the long side and / or the short side) (as in the illustrated example), the center of the bus bar 17a, or the entire bus bar 17a with a width equal to the length of the bus bar 17a. When the connection position is the end, as will be understood from the explanation below, the capacitance can be easily adjusted by separating (cutting) the line L2 (separating at one location allows many electrode fingers 17b to be electrically disconnected from the wiring 19).

[0096] (3.2.2. Cross-sectional structure) Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6. The vibrator 1 may have a dielectric layer 33 interposed between the first substrate 3 and the comb-tooth electrode 17, and a protective film 35 covering the comb-tooth electrode 17. The dielectric layer 33 contributes to increasing the capacitance of the capacitive element 15, for example. The protective film 35 contributes to protecting the comb-tooth electrode 17 and / or the dielectric layer 33 from corrosive substances (for example, air or flux), etc.

[0097] The dielectric layer 33 and / or the protective film 35 may not be provided. All or part of the dielectric layer 33 may be regarded as a component of the capacitive element 15. However, as described above, when referring to the area of ​​the capacitive element 15, the area may be specified based on the electrodes of the capacitive element 15. From another perspective, in specifying the area, only the area of ​​the dielectric layer 33 that overlaps with the arrangement area of ​​the electrodes (including the gaps between the electrodes) may be regarded as constituting the capacitive element 15.

[0098] As shown in FIG. 6 , the dielectric layer 33 extends over all of the capacitance elements 15 (all of the electrodes). From another perspective, the dielectric layer 33 extends at least over the region between the first signal terminal 21S1 and the first GND terminal 21G1 (the inter-terminal region). More specifically, in the illustrated example, the dielectric layer 33 extends just enough over the inter-terminal region. Unlike the illustrated example, the dielectric layer 33 may overlap only some of the capacitance elements 15, or only a portion of each capacitance element 15. The dielectric layer 33 may overlap only a portion of the inter-terminal region and / or extend outward from the inter-terminal region. The dielectric layer 33 may not overlap below or above the external terminal 21. For example, the dielectric layer 33 may be adjacent to the external terminal 21 (as in the illustrated example) or may be spaced apart from the external terminal 21. However, the dielectric layer 33 may overlap a part of the external terminal 21 (for example, the edge on the side of the capacitance element 15).

[0099] The above description of the arrangement area of ​​the dielectric layer 33 may be applied to the arrangement area of ​​the protective film 35. That is, in the above description, the term "dielectric layer 33" may be replaced with the term "protective film 35." Furthermore, the protective film 35 may (or may not) cover not only all of the capacitance elements 15 but also all of the wirings 19. Furthermore, the protective film 35 may or may not cover the entire dielectric layer 33.

[0100] The dielectric layer 33 is formed, for example, with a substantially constant thickness throughout its entirety. From another perspective, the surface on the -D3 side of the dielectric layer 33 is substantially planar. Similarly, the comb-tooth electrode 17 and the wiring 19 are formed, for example, with a substantially constant thickness throughout their entirety, and their -D3 side surfaces are substantially planar. The -D3 side surface of the protective film 35 is, for example, substantially planar. From another perspective, the thickness of the protective film 35 varies depending on the presence or absence of the comb-tooth electrode 17, etc. However, the thickness of the protective film 35 may be substantially constant. From another perspective, the -D3 side surface of the protective film 35 may have irregularities depending on the presence or absence of the comb-tooth electrode 17, etc. Note that the dielectric layer 33 and / or the comb-tooth electrode 17 may also have portions where the thickness or surface height varies.

[0101] The comb-tooth electrodes 17, the wiring 19, the dielectric layer 33, and the protective film 35 may have any thickness. For example, the thickness of the comb-tooth electrodes 17 and / or the wiring 19 may be thinner (in the illustrated example), equal to, or thicker than the thickness of the external terminals 21. The thickness of the dielectric layer 33 may be thinner, equal to, or thicker than the thickness of the external terminals 21 and / or the comb-tooth electrodes 17. The thickness of the protective film 35 (for example, the region covering the comb-tooth electrodes 17) may be thinner, equal to, or thicker than the thickness of the external terminals 21, the comb-tooth electrodes 17, and / or the dielectric layer 33.

[0102] Furthermore, the surface on the -D3 side of the comb-tooth electrode 17 may be lower (or may be on the +D3 side), may be the same height as (in the illustrated example), or may be higher than (in the illustrated example) the surface on the -D3 side of the external terminal 21. The surface on the -D3 side of the protective film 35 (for example, the region covering the comb-tooth electrode 17) may be lower (or may be on the +D3 side), may be the same height as, or may be higher than (in the illustrated example) the surface on the -D3 side of the external terminal 21.

[0103] The material of the comb-tooth electrode 17 is arbitrary. As already mentioned, the comb-tooth electrode 17, the wiring 19, and the external terminal 21 may have one or more layers in common in terms of their materials. For example, the material of the entire thickness of the comb-tooth electrode 17 and the wiring 19 may be the same as the material of part or all of the thickness of the external terminal 21. In this case, the layers of the common material may be located at the same height between different portions (17, 19, and 21) or may be located at different heights. Of course, the comb-tooth electrode 17, the wiring 19, and the external terminal 21 may be made of different materials throughout their entire thicknesses.

[0104] The material of the dielectric layer 33 may be any material as long as its dielectric constant is higher than that of the first substrate 3 (more specifically, the material constituting the first surface 3a). For example, when the material of the first substrate 3 is silicon, the material of the dielectric layer 33 may be tantalum pentoxide (TaO). ２ O ５ The specific value of the dielectric constant of the dielectric layer 33 may also be arbitrary. For example, the relative dielectric constant may be 3 or more, 10 or more, or 20 or more. There is no particular upper limit.

[0105] The material of the protective film 35 is an insulator or a semiconductor (for example, an intrinsic semiconductor). The insulator may be an inorganic material or an organic material (for example, a resin). The material of the protective film 35 may or may not be light-transmitting. In the former case, for example, as shown in FIG. 7 , after the protective film 35 is formed, the comb-tooth electrodes 17 and / or the wiring 19 can be irradiated with laser light LT through the protective film 35 to process these conductors. Specific examples of transparent insulating materials include silicon dioxide (SiO ２ ), alumina (Al ２ O ３ ) and inorganic materials such as silicon nitride (SiN).

[0106] (3.2.3. Processing Area) In Fig. 6, lines L1 to L3 indicate examples of areas processed by laser light. From another perspective, laser processing is, for example, ablation.

[0107] As shown by line L1, the plurality of wirings 19 may be selectively cut by laser processing. As a result, some or all of the plurality of capacitance elements 15 no longer function (or become less likely to function) as capacitance elements 15 electrically interposed between the first signal terminal 21S1 and the first GND terminal 21G1. The same applies below. As a result, the frequency of the oscillation signal generated using the vibrator 1 is adjusted. Note that it is not necessary that all of the wirings 19 are cut as a result.

[0108] 6, the line L1 is shown assuming that the wiring 19 connecting the first signal terminal 21S1 and the capacitance element 15 is cut. However, contrary to the illustrated example, the wiring 19 connecting the capacitance element 15 and the first GND terminal 21G1 may be cut. Also, both of the wirings 19 on both sides of the capacitance element 15 may be cut. As a result of laser processing of the wiring 19, it does not matter if the existence of the wiring 19 before the laser processing cannot be confirmed in the finished vibrator 1.

[0109] As shown by line L2, the busbar 17a of at least one capacitive element 15 may be cut at an appropriate position by laser processing. As a result, the portion of the busbar 17a that is electrically isolated from the wiring 19 and one or more electrode fingers 17b extending from that portion no longer function as part of the capacitive element 15 electrically interposed between the first signal terminal 21S1 and the first GND terminal 21G1. As a result, the frequency of the oscillation signal generated using the vibrator 1 is adjusted. Note that it is not necessary that all of the busbars 17a are cut as a result.

[0110] 6, the line L2 is shown assuming that the bus bar 17a connected to the first signal terminal 21S1 is cut. However, contrary to the illustrated example, the bus bar 17a connected to the first GND terminal 21G1 may be cut. Also, both bus bars 17a may be cut.

[0111] As shown by line L3, an appropriate number of electrode fingers 17b of at least one capacitive element 15 may be cut at appropriate positions by laser processing. As a result, the portion of the electrode finger 17b electrically separated from the bus bar 17a (the portion toward the tip from the cut position) no longer functions as part of the capacitive element 15 electrically interposed between the first signal terminal 21S1 and the first GND terminal 21G1. As a result, the frequency of the oscillation signal generated using the vibrator 1 is adjusted. Note that it is not necessary that all of the electrode fingers 17b are cut off.

[0112] Two or more of the cutting modes indicated by lines L1 to L3 may be combined. For example, the frequency may be adjusted significantly by cutting the wiring 19 (line L1), and the frequency may be adjusted finely by cutting the bus bar 17a and / or electrode fingers 17b (lines L2 and / or L3). It is also possible to adjust the thickness of the electrodes by processing them to finely adjust the frequency.

[0113] Although not particularly shown, in an aspect in which the capacitance element 15 is a parallel plate type that faces each other in a direction along the first surface 3a, for example, the wiring 19 may be cut. Also, for example, at least one of the pair of electrodes may be cut so as to separate the electrode into a portion that is electrically connected to the wiring 19 and a portion that is not electrically connected to the wiring 19. The above two aspects may be combined.

[0114] Furthermore, although not particularly shown, in an aspect in which the capacitance elements 15 are parallel plate-type elements facing each other in the direction facing the first surface 3a, for example, the wiring 19 may be cut. Furthermore, for example, the outer electrode (-D3 side) of the pair of electrodes may be cut so as to separate the outer electrode into a portion that is electrically connected to the wiring 19 and a portion that is not electrically connected to the wiring 19. The above two aspects may be combined.

[0115] In the above, laser processing has been used as an example of a method for cutting (separating) the conductor. However, other methods may be used for cutting the conductor. For example, the conductor may be mechanically cut with a tool blade (cutting in the narrow sense), or may be cut by contacting a heated tool with the conductor.

[0116] (4. Method of Manufacturing Vibrator) The vibrator 1 having the above configuration may be manufactured by various manufacturing methods. An example is shown below. In the following description, even if the shape of a component changes as the manufacturing process progresses, for convenience, the same reference numeral will be assigned to the component before and after the change.

[0117] 8 and 9 are schematic cross-sectional views illustrating an example of a method for manufacturing the vibrator 1. The manufacturing process proceeds in the order of the upper part of FIG. 8, the lower part of FIG. 8, the upper part of FIG. 9, and the lower part of FIG. 9. Each figure corresponds to FIG. 3. For some of the reference numerals described below, please refer to other drawings for convenience.

[0118] 8 and 9 show, for example, processing steps for a wafer including a plurality of first substrates 3, a wafer including a plurality of second substrates 5, and a wafer including a plurality of intermediate layers 7. However, for convenience, these figures only show one first substrate 3, one second substrate 5, and one intermediate layer 7. Note that the wafer referred to in this disclosure is not limited to a substrate made of a semiconductor, but refers to a substrate from which a large number of components are cut out.

[0119] 8, first, a wafer including a plurality of first substrates 3 is prepared. Next, the top surface (the surface on the +D3 side) of this wafer is subjected to appropriate processing to form recesses 3r, conductors (e.g., wiring 27, etc.) on the top surface, and through conductors 29. Note that the through conductors 29 may be formed in this process or in a later process by processing the bottom surface of the wafer.

[0120] Next, as shown in the lower part of Fig. 8, the intermediate layer 7 is bonded to the first substrate 3. At this time, the intermediate layer 7 is not separated into an element component portion 7e and a frame portion 7f. Furthermore, for example, the through-hole 7h is not formed. On the other hand, a conductor layer (for example, the first excitation electrode 13A, the portions of the pair of extraction electrodes 25 on the -D3 side, the auxiliary wiring 31, etc.) located on the lower surface (-D3 side) of the intermediate layer 7 is formed.

[0121] Before bonding the intermediate layer 7 to the first substrate 3, a sacrificial layer may be formed on the upper surface of the first substrate 3. The sacrificial layer is formed on the upper surface of the first substrate 3 on top of the conductor layer on the upper surface of the first substrate 3, and then polished or the like to form the sacrificial layer in the non-conductor layer area at the same height as the conductor layer. This sacrificial layer contributes to supporting the intermediate layer 7 together with the conductor layer. The sacrificial layer is removed at an appropriate time (for example, before bonding the second substrate 5 described below).

[0122] After bonding the intermediate layer 7 to the first substrate 3, as can be seen from a comparison between the lower part of FIG. 8 and the upper part of FIG. 9, the intermediate layer 7 is thinned from the upper surface side. This process may include, for example, a process of significantly thinning the intermediate layer 7 by polishing or wet etching, and a process of thinning the intermediate layer 7 with high precision by plasma CVM (Chemical Vaporization Machining). This thinning process makes the resonant frequency of the excited portion 7a closer to the frequency intended for use, for example. Since the intermediate layer 7 is etched while still in the state of a wafer supported by the wafer of the first substrate 3, it can be processed to be extremely thin.

[0123] 9, the intermediate layer 7 is etched (e.g., wet etching) to separate the element component 7e and the frame 7f and form the through-hole 7h. Next, a conductor layer (e.g., the second excitation electrode 13B and the +D3 side portion of the extraction electrode 25) on the upper surface (+D3 side) of the intermediate layer 7 and the portion of the extraction electrode 25 inside the through-hole 7h are formed.

[0124] 9, the second substrate 5 is bonded to the intermediate layer 7. At this time, a recess 5r is formed in the second substrate 5. A conductor layer (e.g., a metal layer for bonding) is also formed on the lower surface (-D3 side) of the second substrate 5.

[0125] Next, as can be seen from a comparison of the lower part of FIG. 9 with FIG. 3 , the first substrate 3 is thinned from the side of the first surface 3 a, and the second substrate 5 is thinned from the side of the second surface 5 a. This process may be achieved by polishing and / or etching (e.g., wet etching). Thereafter, a conductor layer (e.g., external terminals 21) is formed on the first surface 3 a of the first substrate 3. In an embodiment different from the illustrated example, a conductor layer may be formed on the upper surface of the second substrate 5, similar to the first substrate 3.

[0126] 7 is formed before or after the formation of the external terminals 21. After the formation of the dielectric layer 33, the comb-tooth electrodes 17 and the wiring 19 are formed before, during, and / or after the formation of the external terminals 21. After the formation of the comb-tooth electrodes 17 and the wiring 19 (before or after the formation of the external terminals 21), a protective film 35 is formed.

[0127] 7, laser processing is performed on the wiring 19 and / or the comb-tooth electrode 17 via the protective film 35. At this time, for example, an AC voltage may be applied to the two signal terminals 21S, and the frequency characteristics of the vibrator 1 may be detected appropriately.

[0128] Thereafter, the wafer is divided into a plurality of vibrators 1. The division into individual pieces may be performed before the above-mentioned laser processing (frequency adjustment).

[0129] (5. Summary of the embodiment) As described above, the piezoelectric vibration device (vibrator 1) according to the embodiment has a vibration portion 9 and a package 11 that seals the vibration portion 9. The vibration portion 9 has an excitation electrode 13 and a portion (excited portion 7a) of the piezoelectric body (intermediate layer 7) that overlaps with the excitation electrode 13. The package 11 has a first base (first substrate 3), a second base (second substrate 5), and one or more capacitance elements 15. The first substrate 3 faces the vibration portion 9 across a space. The second substrate 5 faces the vibration portion 9 from the side opposite the first substrate 3 across a space. The one or more capacitance elements 15 are located on a first surface 3a of the first substrate 3 that faces the side opposite the vibration portion 9. In a planar perspective view of the first surface 3a, all of the capacitance elements 15 are offset from the excitation electrode 13.

[0130] Therefore, for example, as described in the overview of the embodiment, it is possible to reduce unintended changes in stray capacitance and reduce the probability of unintended processing of the excitation electrode 13.

[0131] In a planar perspective view of the first surface 3a, none of the capacitance elements 15 may overlap the excitation electrodes 13. In this case, for example, the above-described effects are improved.

[0132] The package 11 may have a plurality of external terminals 21 arranged on the first surface 3a along the outer edge of the first surface 3a. The plurality of external terminals 21 may include a signal terminal (first signal terminal 21S1) electrically connected to one of the excitation electrodes 13 and a reference potential terminal (first GND terminal 21G1) adjacent to the first signal terminal 21S1 along the outer edge of the first surface 3a. The one or more capacitive elements 15 located on the first surface 3a may include at least one capacitive element 15 located in an inter-terminal region between the first signal terminal 21S1 and the first GND terminal 21G1 on the first surface 3a (see the arrangement range of the dielectric layer 33 in FIG. 6 ).

[0133] In this case, for example, by ensuring that an area for arranging at least one capacitance element 15 is located in the inter-terminal area, it becomes easy to arrange all capacitance elements 15 so as to avoid the excitation electrodes 13. In addition, it becomes easy to simplify or shorten the path of the wiring 19 that connects the capacitance element 15 and the external terminal 21 (or that was connected before the laser processing).

[0134] The at least one capacitance element 15 located in the inter-terminal region may be a plurality of capacitance elements 15 (for example, all capacitance elements 15). In this case, for example, the above-described effects are improved.

[0135] The plurality of capacitive elements 15 located in the inter-terminal region may be aligned in a direction (direction D1) that intersects with the alignment direction of the first signal terminal 21S1 and the first GND terminal 21G1.

[0136] In this case, for example, it becomes easier to simplify and / or shorten the path of the wiring 19 of multiple capacitance elements 15 that are connected in parallel to the first signal terminal 21S1 and the first GND terminal 21G1 (or were connected in parallel before laser processing).

[0137] The at least one capacitive element 15 contained in the inter-terminal region may include a capacitive element 15 that electrically connects the first signal terminal 21S1 and the first GND terminal 21G1.

[0138] The above may refer to the vibrator 1 before laser processing or may refer to the vibrator 1 after laser processing. In either case, the capacitive element 15 contributes to frequency adjustment. By displacing such capacitive element 15 from the excitation electrode 13, the accuracy of frequency adjustment is improved.

[0139] In a planar perspective view of the first surface 3 a, the excitation electrode 13 may be located on one side (+D1 side) in a predetermined direction (D1 direction) with respect to the center of the first surface 3 a, and the one or more capacitance elements 15 located on the first surface 3 a may be located on the other side (-D1 side) in the D1 direction with respect to the center of the first surface 3 a.

[0140] In this case, the capacitance elements 15 and the excitation electrodes 13 are arranged on the first surface 3a so as to be biased toward opposite sides to each other, which makes it easier to prevent them from overlapping. From another perspective, it is easier to secure a congregate arrangement area for the capacitance elements 15 compared to, for example, an embodiment in which the excitation electrodes 13 are arranged in the center of the first surface 3a. As a result, for example, it is possible to increase the size of each capacitance element 15 and shorten the path of the wiring 19 connected to the plurality of capacitance elements 15.

[0141] The first surface 3a may be rectangular. The package 11 may have four external terminals 21 located at four corners of the first surface 3a. The four external terminals 21 may include two external terminals 21 (a first signal terminal 21S1 and a first GND terminal 21G1) adjacent to each other along one side of the first surface 3a. In a planar perspective view of the first surface 3a, the excitation electrode 13 may be located between the two external terminals 21.

[0142] In this case, it is easier to increase the area of ​​the inter-terminal region between two external terminals compared to, for example, a configuration in which three or more external terminals 21 are located along one side, which in turn makes it easier to secure an area for arranging the capacitive element 15.

[0143] At least one of the one or more capacitance elements 15 located on the first surface 3a may have a pair of interdigitated comb electrodes 17.

[0144] In this case, for example, it is easy to ensure the capacitance. Also, for example, as shown by line L2 in Fig. 6 , the capacitance can be adjusted in units of the capacitance associated with one electrode finger 17b, or as shown by line L3, the capacitance can be adjusted in units of less than the capacitance associated with one electrode finger (line L3).

[0145] The vibrator 1 may have a dielectric layer 33 interposed between the first surface 3a and the comb-tooth electrode 17 and having a higher dielectric constant than the material that constitutes the first surface 3a.

[0146] In this case, for example, it is possible to increase the capacitance of the capacitive element 15. From the opposite perspective, the need to consider the capacitance of the capacitive element 15 when setting the material of the first surface 3 a is reduced, and the degree of freedom in designing the first substrate 3 is improved.

[0147] The package 11 may have a protective film 35 made of a transparent inorganic material that covers at least a portion of one or more capacitive elements 15 located on the first surface 3a.

[0148] In this case, for example, as described above, the electrodes (comb-tooth electrodes 17) of the capacitance element 15 are protected from corrosion and the like, and laser processing of the electrodes (or wiring 19) can be performed from above the protective film 35.

[0149] The package 11 may include the outer periphery (frame portion 7f or its outer periphery) of the piezoelectric body (intermediate layer 7) in a planar perspective view of the first surface 3a. The frame portion 7f may be sandwiched between the first substrate 3 and the second substrate 5, thereby sealing the vibrating portion 9 surrounded by the frame portion 7f in a planar perspective view of the first surface 3a.

[0150] That is, the package 11 may be a three-layer structure and / or a WLP (Wafer Level Packaging) type. In such a configuration, the vibrator 1 is often thin. Consequently, the distance between the excitation electrode 13 and the capacitive element 15 located on the first surface 3a tends to be short. Therefore, the effects related to the stray capacitance and / or laser processing described above are effectively utilized.

[0151] A manufacturing method for a piezoelectric vibration device (vibrator 1) according to the embodiment may include laser processing of a conductor located on the first surface 3a. The package 11 before the laser processing may have a signal terminal (first signal terminal 21S1), a reference potential terminal (first GND terminal 21G1), and the conductor. The first signal terminal 21S1 may be located on the first surface 3a and electrically connected to the excitation electrode 13. The first GND terminal 21G1 may be located on the first surface 3a. The conductor may electrically connect the first signal terminal 21S1 and the first GND terminal 21G1 and may include some or all of the electrodes (comb-tooth electrodes 17) of one or more capacitance elements 15 located on the first surface 3a. The laser processing may adjust the capacitance between the first signal terminal 21S1 and the first GND terminal 21G1 by cutting the conductor. The laser processing may be prevented from being performed on the area of ​​the first surface 3a that overlaps with the excitation electrode 13 in a planar perspective view.

[0152] In this case, for example, as already described, the probability that unintended processing is performed on the excitation electrode 13 is reduced.

[0153] The manufacturing method according to the embodiment may include polishing the first surface 3a after fixing the first substrate 3 and the second substrate 5 to each other (see the bottom of Figure 9 and Figure 3), and forming one or more capacitive elements 15 after polishing (see Figure 7).

[0154] In this case, for example, since the first surface 3a is polished after bonding, it is easy to make the first substrate 3 thin. In other words, it is easy to make the vibrator 1 small in size.

[0155] The technology according to the present disclosure is not limited to the above-described embodiment and may be implemented in various forms. For example, the piezoelectric vibration device is not limited to a vibrator. For example, as already mentioned, the piezoelectric vibration device may be an oscillator having an oscillation circuit. Furthermore, for example, the piezoelectric vibration device may be used for purposes other than generating an oscillation signal, such as filtering.

[0156] The following concepts may be extracted from the present disclosure. (Concept 1) A piezoelectric vibration device comprising: a vibration section having an excitation electrode and a portion of a piezoelectric body overlapping with the excitation electrode; and a package sealing the vibration section, wherein the package comprises: a first base facing the vibration section across a space; a second base facing the vibration section across a space from the opposite side to the first base; and one or more capacitance elements located on a first surface of the first base facing the side opposite to the vibration section, wherein all of the capacitance elements are offset from the excitation electrode in a planar perspective view of the first surface. (Concept 2) The piezoelectric vibration device according to Concept 1, wherein none of the capacitance elements overlap with the excitation electrode in a planar perspective view of the first surface. (Concept 3) The piezoelectric vibration device according to Concept 1 or 2, wherein the package has a plurality of external terminals arranged on the first surface along an outer edge of the first surface, the plurality of external terminals including a signal terminal electrically connected to one of the excitation electrodes and a reference potential terminal adjacent to the signal terminal along the outer edge, and the one or more capacitive elements include at least one capacitive element located in an inter-terminal area on the first surface between the signal terminal and the reference potential terminal. (Concept 4) The piezoelectric vibration device according to Concept 3, wherein the at least one capacitive element located in the inter-terminal area is a plurality of capacitive elements. (Concept 5) The piezoelectric vibration device according to Concept 4, wherein the plurality of capacitive elements located in the inter-terminal area are aligned in a direction intersecting an alignment direction of the signal terminal and the reference potential terminal. (Concept 6) The piezoelectric vibration device according to any one of Concepts 3 to 5, wherein the at least one capacitive element located in the inter-terminal area includes a capacitive element electrically connecting the signal terminal and the reference potential terminal. (Concept 7) A piezoelectric vibration device described in any one of Concepts 1 to 6, wherein, in a planar perspective view of the first surface, the excitation electrode is located on one side of the center of the first surface in a predetermined direction, and all of the capacitance elements are located on the other side of the center of the first surface in the predetermined direction.(Concept 8) The piezoelectric vibration device according to Concept 7, wherein the first surface is rectangular, the package has four external terminals located at four corners of the first surface, the four external terminals including two external terminals adjacent to each other along one side of the first surface, and the excitation electrode is located between the two external terminals in a planar perspective view of the first surface. (Concept 9) The piezoelectric vibration device according to any one of Concepts 1 to 8, wherein at least one of the one or more capacitive elements has a pair of interdigital electrodes that are interdigitated with each other. (Concept 10) The piezoelectric vibration device according to Concept 9, wherein a dielectric layer is interposed between the first surface and the comb-tooth electrodes and has a dielectric constant higher than that of a material constituting the first surface. (Concept 11) The piezoelectric vibration device according to any one of Concepts 1 to 10, wherein the package has a protective film containing a transparent insulating material and covering at least a portion of the one or more capacitive elements. (Concept 12) The piezoelectric vibration device according to any one of Concepts 1 to 11, wherein the package includes an outer periphery of the piezoelectric body in a planar perspective of the first surface, and the outer periphery is sandwiched between the first base and the second base, thereby sealing the vibration portion surrounded by the outer periphery in the planar perspective of the first surface. (Concept 13) A method for manufacturing a piezoelectric vibration device according to any one of Concepts 1 to 12, comprising laser processing of a conductor located on the first surface, wherein the package before the laser processing has: a signal terminal located on the first surface and electrically connected to the excitation electrode, a reference potential terminal located on the first surface, and the conductor electrically connecting the signal terminal and the reference potential terminal, and including some or all of the electrodes of the one or more capacitive elements, wherein the laser processing adjusts a capacitance between the signal terminal and the reference potential terminal by cutting the conductor, and wherein the laser processing is not performed on an area that overlaps with the excitation electrode in the planar perspective of the first surface.(Concept 14) A method for manufacturing a piezoelectric vibration device according to Concept 13, comprising: polishing the first surface after fixing the first substrate and the second substrate to each other; and forming the one or more capacitive elements after the polishing.

[0157] Concepts different from those described above may be extracted from the present disclosure. For example, concepts such as arranging one or more capacitance elements in the region between the external terminals, using comb-tooth electrodes, or providing a transparent protective film to cover the capacitance elements may be extracted. In such concepts, it is not essential that the capacitance elements are offset from the excitation electrodes.

[0158] 1...quartz crystal oscillator (piezoelectric oscillator device), 3...first substrate (first base), 3a...first surface, 5...second substrate (second base), 7...intermediate layer (piezoelectric body), 9...vibration portion, 11...package, 13...excitation electrode, 15...capacitive element.

Claims

1. A piezoelectric vibration device comprising: a vibration section having an excitation electrode and a portion of a piezoelectric body where the excitation electrode overlaps; and a package sealing the vibration section, wherein the package comprises: a first base facing the vibration section across a space; a second base facing the vibration section across a space from the opposite side of the first base; and one or more capacitance elements located on a first surface of the first base facing the opposite side to the vibration section, wherein all of the capacitance elements are offset from the excitation electrode when viewed from above in perspective of the first surface.

2. The piezoelectric vibration device according to claim 1, wherein none of the capacitance elements overlaps with the excitation electrodes in a planar perspective view of the first surface.

3. A piezoelectric vibration device as described in claim 1 or 2, wherein the package has a plurality of external terminals arranged on the first surface along the outer edge of the first surface, the plurality of external terminals including a signal terminal electrically connected to one of the excitation electrodes and a reference potential terminal adjacent to the signal terminal along the outer edge, and the one or more capacitive elements include at least one capacitive element located in an inter-terminal area on the first surface between the signal terminal and the reference potential terminal.

4. The piezoelectric vibrating device according to claim 3, wherein the at least one capacitive element contained in the inter-terminal region is a plurality of capacitive elements.

5. The piezoelectric vibration device according to claim 4, wherein the plurality of capacitance elements contained in the inter-terminal region are arranged in a direction intersecting the arrangement direction of the signal terminal and the reference potential terminal.

6. A piezoelectric vibration device according to any one of claims 3 to 5, wherein the at least one capacitive element contained in the inter-terminal region includes a capacitive element electrically connecting the signal terminal and the reference potential terminal.

7. A piezoelectric vibration device as described in any one of claims 1 to 6, wherein, in a planar perspective view of the first surface, the excitation electrode is located on one side of the center of the first surface in a predetermined direction, and all of the capacitance elements are located on the other side of the center of the first surface in the predetermined direction.

8. A piezoelectric vibration device as described in claim 7, wherein the first surface is rectangular, the package has four external terminals located at four corners of the first surface, the four external terminals include two external terminals adjacent to each other along one side of the first surface, and in a planar perspective view of the first surface, the excitation electrode is located between the two external terminals.

9. A piezoelectric vibration device according to any one of claims 1 to 8, wherein at least one of the one or more capacitive elements has a pair of interdigitated comb electrodes.

10. The piezoelectric vibration device according to claim 9, further comprising a dielectric layer interposed between the first surface and the comb-tooth electrode and having a higher dielectric constant than the material constituting the first surface.

11. A piezoelectric vibrating device according to any one of claims 1 to 10, wherein the package has a protective film containing a transparent insulating material that covers at least a portion of the one or more capacitive elements.

12. A piezoelectric vibration device as described in any one of claims 1 to 11, wherein the package includes the outer periphery of the piezoelectric body in a planar perspective of the first surface, and the outer periphery is sandwiched between the first base and the second base, thereby sealing the vibration part surrounded by the outer periphery in a planar perspective of the first surface.

13. A method for manufacturing a piezoelectric vibration device according to any one of claims 1 to 12, comprising laser processing of a conductor located on the first surface, wherein the package before the laser processing has: a signal terminal located on the first surface and electrically connected to the excitation electrode; a reference potential terminal located on the first surface; and the conductor electrically connecting the signal terminal and the reference potential terminal and including some or all of the electrodes of the one or more capacitive elements, wherein the laser processing adjusts the capacitance between the signal terminal and the reference potential terminal by cutting the conductor, and wherein the laser processing is not performed on an area of ​​the first surface that overlaps with the excitation electrode in a planar perspective view.

14. A method for manufacturing a piezoelectric vibration device as described in claim 13, comprising: polishing the first surface after fixing the first substrate and the second substrate to each other; and forming the one or more capacitive elements after the polishing.

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