Piezoelectric vibration element

Abstract

A piezoelectric vibration element (10) is provided with: a piezoelectric sheet (11); a first excitation electrode (14a) provided on the first main surface (11A) of the piezoelectric sheet (11); a second excitation electrode (14b) provided on a second main surface (11B) of the piezoelectric sheet (11); and a mass-added film (20) at least partially overlapping the first excitation electrode (14a), the mass-added film (20) including a first portion (21) and a second portion (22) provided so as to avoid a center portion of the first excitation electrode (14a), the first excitation electrode (14a) having a first outer edge portion (71) and a second outer edge portion (72) in plan view, the second excitation electrode (14b) having a third outer edge portion (81) and a fourth outer edge portion (82), and the third outer edge portion (81) and the fourth outer edge portion (82) being disposed so as to overlap the first outer edge portion (71) and the second outer edge portion (72) in plan view. The first portion (21) is provided along the first outer edge portion (71), the second portion (22) is provided along the second outer edge portion (72), and a region where the piezoelectric sheet (11), the first excitation electrode (14a), and the second excitation electrode (14b) overlap is defined as a high acoustic velocity region (17). When a first low-sound-velocity region (18A) and a second low-sound-velocity region (18B) are defined as regions in which the mass-added film (20) is further overlapped on the piezoelectric sheet (11), the first excitation electrode (14a), and the second excitation electrode (14b), the third outer edge portion (81) and the fourth outer edge portion (82) are farther from the central portion than the first low-sound-velocity region (18A) and the second low-sound-velocity region (18B), respectively, in plan view.

Description

Technical Field

[0001] The present invention relates to a piezoelectric vibration element. Background Art

[0002] In various electronic devices such as mobile communication terminals, communication base stations, and home appliances, piezoelectric vibration elements are used in timing devices, sensors, or oscillators. The piezoelectric vibration element includes a piezoelectric sheet having a pair of main surfaces and a pair of excitation electrodes provided on the pair of main surfaces of the piezoelectric sheet.

[0003] For example, Patent Document 1 discloses a crystal vibration element comprising: a crystal piece having a first principal surface and a second principal surface; a first excitation electrode arranged on the first principal surface; and a second excitation electrode arranged on the second principal surface, wherein the first excitation electrode and the second excitation electrode have a film thickness portion at the electrode end portion that is thicker than other portions.

[0004] Patent Document 1: International Publication No. 2022 / 080426

[0005] However, in the crystal resonator element described in Patent Document 1, there is a case where the electromechanical coupling coefficient deteriorates due to positional deviation of the film thickness portion caused by manufacturing variation. Summary of the invention

[0006] The present invention has been made in view of such circumstances, and provides a piezoelectric vibration element capable of suppressing deterioration of the electromechanical coupling coefficient.

[0007] A piezoelectric vibration element of a technical solution of the present invention comprises: a piezoelectric sheet having a first main surface extending in a first direction and a second direction intersecting the first direction, and a second main surface opposite to the first main surface; a first excitation electrode arranged on the first main surface of the piezoelectric sheet; a second excitation electrode arranged on the second main surface of the piezoelectric sheet; and a mass addition film, at least a portion of which overlaps with the first excitation electrode, the mass addition film including a first portion and a second portion arranged to avoid a central portion of the first excitation electrode, the first excitation electrode having, when viewed from above, a first outer edge portion located on one side of the first direction relative to the central portion; and a second outer edge portion located on the other side of the first direction relative to the central portion, the second excitation electrode having, when viewed from above, a first outer edge portion located on the other side of the first direction relative to the central portion A third outer edge portion on one side in the first direction; and a fourth outer edge portion on the other side in the first direction relative to the central portion, the first portion is arranged along the first outer edge portion, and the second portion is arranged along the second outer edge portion, when the area where the piezoelectric sheet, the first excitation electrode and the second excitation electrode overlap is set as a high acoustic velocity area, the area where the first part of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as a first low acoustic velocity area, and the area where the second part of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as a second low acoustic velocity area, when viewed from above, the third outer edge portion is farther away from the central portion than the first low acoustic velocity area, and when viewed from above, the fourth outer edge portion is farther away from the central portion than the second low acoustic velocity area.

[0008] A piezoelectric vibration element of a technical solution of the present invention comprises: a piezoelectric sheet having a first main surface extending in a first direction and a second direction intersecting the first direction, and a second main surface opposite to the first main surface; a first excitation electrode arranged on the first main surface of the piezoelectric sheet; a second excitation electrode arranged on the second main surface of the piezoelectric sheet; and a mass addition film, at least a portion of which overlaps with the first excitation electrode, the mass addition film including a first portion and a second portion arranged avoiding a central portion of the first excitation electrode, the first excitation electrode having, when viewed from above, a first outer edge portion located on one side in the first direction relative to the central portion; and a second outer edge portion located on the other side in the first direction relative to the central portion, the second excitation electrode having, when viewed from above, a third outer edge portion located on one side in the first direction relative to the central portion; and a fourth outer edge portion located on the other side in the first direction relative to the central portion, the first portion being arranged along the first outer edge portion, the second portion being arranged along the second outer edge portion, and the piezoelectric sheet, the first excitation electrode, and The region where the second excitation electrode overlaps is set as the high acoustic velocity region, the region where the first part of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as the first low acoustic velocity region, and the region where the second part of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as the second low acoustic velocity region. When the dimension along the first direction between the end of the first part on the side opposite to the second part and the end of the second part on the side opposite to the first part in the mass addition film is set as A, the dimension of the first excitation electrode along the first direction is set as B, and the dimension of the second excitation electrode along the first direction is set as C, the relationship A=C<B holds. When viewed from above, the outer edge of the first low acoustic velocity region on the side opposite to the second low acoustic velocity region and the outer edge of the second low acoustic velocity region on the side opposite to the first low acoustic velocity region overlap with the first excitation electrode, and when viewed from above, the third outer edge and the fourth outer edge of the second excitation electrode overlap with the first excitation electrode.

[0009] According to the present invention, it is possible to provide a piezoelectric vibration element capable of suppressing deterioration of the electromechanical coupling coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view of the crystal oscillator according to the first embodiment.

[0011] Figure 2 It is an exploded perspective view of the crystal oscillator according to the first embodiment.

[0012] Figure 3 It is a cross-sectional view of the crystal oscillator according to the first embodiment.

[0013] Figure 4 It is a cross-sectional view of the crystal resonator element according to the first embodiment.

[0014] Figure 5 It is a top view of the crystal resonator element according to the first embodiment.

[0015] Figure 6 This is a table showing the conditions of the simulation based on the first embodiment.

[0016] Figure 7 It is a graph showing the simulation results based on the first embodiment.

[0017] Figure 8 It is a graph showing the simulation results based on the first embodiment.

[0018] Fig. 9 It is a graph showing the simulation results based on the first embodiment.

[0019] Fig.10 It is a graph showing the simulation results based on the first embodiment.

[0020] Fig.11 It is a graph showing the simulation results based on the first embodiment.

[0021] Fig.12 It is a graph showing the simulation results based on the first embodiment.

[0022] Fig.13 It is a graph showing the simulation results based on the first embodiment.

[0023] Fig.14 It is a graph showing the simulation results based on the first embodiment.

[0024] Fig.15 It is a graph showing the simulation results based on the first embodiment.

[0025] Fig.16 It is a graph showing the simulation results based on the first embodiment.

[0026] Fig.17 This is a diagram for explaining the influence of positional deviation in the first embodiment.

[0027] Fig.18 This is a diagram for explaining the influence of positional deviation in the first embodiment.

[0028] Fig.19 It is a cross-sectional view of the crystal resonator element according to the second embodiment.

[0029] Fig. 20 It is a cross-sectional view of a crystal resonator element according to the third embodiment.

[0030] Fig.21 It is a cross-sectional view of a crystal resonator element according to a fourth embodiment.

[0031] Fig. 22 It is a diagram for explaining the influence of positional deviation in the fourth embodiment.

[0032] Fig.23 It is a diagram for explaining the influence of positional deviation in the fourth embodiment.

[0033] Fig.24 It is a cross-sectional view of the crystal resonator element according to the fifth embodiment.

[0034] Fig.25 It is a diagram for explaining the influence of positional deviation in the fifth embodiment.

[0035] Fig.26 It is a diagram for explaining the influence of positional deviation in the fifth embodiment.

[0036] Fig. 27 It is a cross-sectional view of the crystal resonator element according to the sixth embodiment.

[0037] Fig.28 It is a diagram for explaining the influence of positional deviation in the sixth embodiment.

[0038] Fig.29 It is a diagram for explaining the influence of positional deviation in the sixth embodiment.

[0039] Fig.30 It is a cross-sectional view of a crystal resonator element according to the seventh embodiment.

[0040] Fig.31 It is a cross-sectional view of a crystal resonator element according to the eighth embodiment.

[0041] Fig.32 : is a table showing simulation results of comparative examples and examples based on the first to eighth embodiments.

[0042] Fig.33 This is a table showing simulation conditions of comparative examples and examples based on the first to eighth embodiments.

[0043] Fig.34 It is a cross-sectional view of a crystal resonator element according to the ninth embodiment.

[0044] Fig.35 It is a top view of the crystal resonator element according to the tenth embodiment.

[0045] Fig.36 It is a top view of the crystal resonator element according to the eleventh embodiment. DETAILED DESCRIPTION

[0046] The following is a description of the embodiments of the present invention. In the following description of the accompanying drawings, the same or similar structural elements are represented by the same or similar reference numerals. The accompanying drawings are illustrative, and the size and shape of each part are schematic, and the technical scope of the present invention should not be limited to the embodiment for interpretation. In addition, in the following description, "size" refers to the length of an object, and "distance" refers to the length of the interval between two objects.

[0047] In each of the drawings, in order to clarify the relationship between the drawings and to help understand the positional relationship of the components, an orthogonal coordinate system consisting of an X-axis, a Y'axis, and a Z'axis is sometimes marked for convenience. The X-axis, the Y'axis, and the Z'axis correspond to each other in each of the drawings. The X-axis, the Y'axis, and the Z'axis correspond to the crystal axes (Crystallographic Axes) of the crystal sheet 11 described later, respectively. The X-axis is equivalent to the electrical axis (polar axis) of the crystal, the Y-axis is equivalent to the mechanical axis of the crystal, and the Z-axis is equivalent to the optical axis of the crystal. The Y'axis and the Z'axis are axes obtained by rotating the Y-axis and the Z-axis around the X-axis from the Y-axis to the Z-axis by 35 degrees 15 minutes ± 1 minute 30 seconds.

[0048] In the following description, the direction parallel to the X-axis is referred to as the "X-axis direction", the direction parallel to the Y'-axis is referred to as the "Y'-axis direction", and the direction parallel to the Z'-axis is referred to as the "Z'-axis direction". In addition, the tip directions of the arrows of the X-axis, Y'-axis, and Z'-axis are referred to as "positive" or "+(positive)", and the directions opposite to the arrows are referred to as "negative" or "-(negative)". In addition, for convenience, the +Y'-axis direction is set as the upward direction and the -Y'-axis direction is set as the downward direction for description, but the upper and lower directions of the crystal vibration element 10, the crystal resonator 1, and the crystal oscillator 100 are not limited. In addition, the plane determined by the X-axis and the Z'-axis is referred to as the Z'X plane, and the same applies to the planes determined by other axes.

[0049] <First embodiment>

[0050] First, refer to Figure 1 , a schematic structure of a crystal oscillator according to an embodiment is described. is a cross-sectional view of the crystal oscillator according to the first embodiment.

[0051] In the following description, a crystal oscillator (XO: Crystal Oscillator) having a crystal oscillator (Quartz Crystal Resonator Unit) is exemplified as a piezoelectric oscillator. In addition, a crystal oscillator (Quartz Crystal Resonator Unit) having a crystal resonator element (Quartz Crystal Resonator) is exemplified as a piezoelectric oscillator (Piezoelectric Resonator Unit). In addition, a crystal resonator element having a crystal piece (Quartz Crystal Element) is exemplified as a piezoelectric resonator element. A crystal piece is a type of piezoelectric body (piezoelectric piece) that vibrates in response to applied voltage. In addition, piezoelectric oscillators are not limited to crystal oscillators, and other piezoelectric bodies such as ceramics may also be used. Similarly, piezoelectric oscillators are not limited to crystal oscillators, and other piezoelectric bodies such as ceramics may also be used. In addition, similarly, piezoelectric resonators are not limited to crystal oscillators, and other piezoelectric bodies such as ceramics may also be used. In addition, similarly, piezoelectric resonator elements are not limited to crystal resonator elements, and other piezoelectric bodies such as ceramics may also be used.

[0052] like Figure 1 As shown, the crystal oscillator 100 includes a crystal unit 1 , a mounting substrate 130 , a cover 140 , and an electronic component 156 .

[0053] The crystal oscillator 1 and the electronic component 156 are accommodated in a space formed between the mounting substrate 130 and the cover 140. The space formed by the mounting substrate 130 and the cover 140 is, for example, hermetically sealed. In addition, the space may be hermetically sealed in a vacuum state or may be hermetically sealed in a state filled with a gas such as an inert gas.

[0054] The mounting substrate 130 is a flat circuit substrate and is configured to include, for example, a glass epoxy board and a wiring layer patterned on the glass epoxy board.

[0055] The crystal oscillator 1 is provided on one surface ( Figure 1 More specifically, the crystal oscillator 1 is electrically connected to the wiring layer of the mounting substrate 130 through the solder 153.

[0056] The cover 140 includes a side ( Figure 1 In other words, the cover 140 includes: a flat top wall, a side wall extending from the outer edge of the top wall toward the mounting substrate 130, and a flange extending from the front end of the side wall toward the outside. The flange is connected to one surface ( Figure 1Thus, the crystal oscillator 1 bonded to the mounting substrate 130 is housed inside the cover 140. The cover 140 is made of a metal material, for example, formed by drawing a metal plate.

[0057] The electronic component 156 is provided on one surface ( Figure 1 More specifically, the wiring layer of the mounting substrate 130 and the electronic component 156 are joined by the solder 153. Thus, the electronic component 156 is mounted on the mounting substrate 130.

[0058] The electronic component 156 is electrically connected to the crystal oscillator 1 through the wiring layer of the mounting substrate 130. The electronic component 156 is configured to include, for example, a capacitor, an IC chip, etc. The electronic component 156 is, for example, a part of an oscillation circuit that causes the crystal oscillator 1 to oscillate, or a part of a temperature compensation circuit that compensates for the temperature characteristics of the crystal oscillator 1. In the case where the electronic component 156 includes a temperature compensation circuit, the crystal oscillator 100 is equivalent to an example of a temperature compensated crystal oscillator (TCXO: Temperature Compensated Crystal Oscillator). The crystal oscillator 100 can also be equivalent to an example of a voltage controlled crystal oscillator (VCXO: Voltage Controlled Crystal Oscillator), and can also be equivalent to an example of a crystal oscillator with a constant temperature bath (OCXO: Oven Controlled Crystal Oscillator).

[0059] Next, refer to Figure 2 And 3, the structure of the crystal oscillator 1 of the first embodiment is described. Figure 2 It is an exploded perspective view of the crystal oscillator according to the first embodiment. Figure 3 It is a cross-sectional view of the crystal oscillator according to the first embodiment.

[0060] The Z'-axis direction is an example of a "first direction", the X-axis direction is an example of a "second direction", and the Y'-axis direction is an example of a "third direction". The Y'-axis direction is an example of a "thickness direction". The first direction, the second direction, and the third direction are not limited to the above. For example, the X-axis direction may be the first direction, and the Z'-axis direction may be the second direction.

[0061] The crystal oscillator 1 includes a crystal oscillating element 10 , a base member 30 , a cover member 40 , and a bonding portion 50 .

[0062] The crystal resonator element 10 is an electromechanical energy conversion element that converts electrical energy and mechanical energy into each other through the piezoelectric effect. The frequency of the main mode of the crystal resonator element 10 is, for example, about 0.8 GHz or more and about 2.0 GHz or less, for example, about 0.95 GHz. The frequency of the non-harmonic mode of the crystal resonator element 10 is, for example, in the range of about 1% of the frequency of the main mode. The crystal resonator element 10 comprises: a thin sheet-like crystal element (Quartz Crystal Element) 11, a first excitation electrode 14a and a second excitation electrode 14b constituting a pair of excitation electrodes, a first extraction electrode 15a and a second extraction electrode 15b constituting a pair of extraction electrodes, a first connection electrode 16a and a second connection electrode 16b constituting a pair of connection electrodes, and a mass addition film 20.

[0063] The crystal piece 11 has an upper surface 11A and a lower surface 11B facing each other. The upper surface 11A is located on the side facing the top wall portion 41 of the cover member 40. The lower surface 11B is located on the side facing the base member 30. The upper surface 11A and the lower surface 11B correspond to a pair of main surfaces of the crystal piece 11.

[0064] The crystal piece 11 is, for example, an AT-cut crystal crystal. The AT-cut crystal crystal is formed with the XZ' plane as the main surface and the direction parallel to the Y' axis as the thickness. As an example, when looking down at the upper surface 11A in the thickness direction (hereinafter referred to as "looking down"), the shape of the crystal piece 11 (hereinafter referred to as "planar shape") is a square having a pair of sides extending in the Z' axis direction and a pair of sides extending in the X-axis direction. In addition, the crystal piece 11 has a thickness in the Y' axis direction. As an example, the shape of the crystal piece 11 is a flat plate with uniform thickness.

[0065] In addition, the planar shape of the crystal piece is not limited to the above. For example, the planar shape of the crystal piece may also be a rectangle having a long side extending in the Z'-axis direction and a short side extending in the X-axis direction, or a rectangle having a short side extending in the Z'-axis direction and a long side extending in the X-axis direction. The planar shape of the crystal piece may also be polygonal, circular, elliptical, or a combination thereof. In addition, the crystal piece is not limited to a flat plate. The crystal piece may also be a table-type structure or an inverted table-type structure having a concave and convex shape in at least one of the upper surface 11A and the lower surface 11B. The crystal piece may also be a convex structure in which the amount of change in thickness changes continuously, or it may be an inclined structure in which the amount of change in thickness changes discontinuously.

[0066] The AT-cut crystal piece 11 is a crystal piece cut out by rotating the crystal axes of an artificial crystal (Synthetic Quartz Crystal), i.e., the X-axis, Y-axis, and Z-axis, around the X-axis by 35 degrees and 15 minutes ± 1 minute and 30 seconds from the Y-axis to the Z-axis, and setting the axes obtained as the Y' axis and the Z' axis respectively, and using the XZ' plane as the main surface.

[0067] The crystal vibrating element 10 using the AT-cut crystal plate 11 has high frequency stability in a wide temperature range. In addition, the AT-cut crystal vibrating element is also excellent in time-varying characteristics and can be manufactured at low cost. In addition, the AT-cut crystal vibrating element uses the thickness shear vibration mode as the main vibration.

[0068] In addition, the cutting angle of the crystal piece is not limited to the above. The rotation angle of the Y' axis and the Z' axis in the AT-cut crystal piece 11 can also be tilted within the range of -5 degrees or more or +15 degrees or less from 35 degrees and 15 minutes. In addition, the cutting angle of the crystal piece can also be applied to different cuts other than AT cutting, such as BT cutting, GT cutting, SC cutting, etc. In addition, the main vibration mode of the crystal vibration element is not limited to the thickness sliding shear mode, for example, it can also be thickness longitudinal vibration, extension vibration, length vibration or bending vibration.

[0069] The first excitation electrode 14a and the second excitation electrode 14b apply an alternating voltage to the crystal piece 11 to excite the crystal piece 11. The first excitation electrode 14a and the second excitation electrode 14b are provided at the central portion of the crystal piece 11 when viewed from above. The first excitation electrode 14a is provided on the upper surface 11A, and the second excitation electrode 14b is provided on the lower surface 11B. The first excitation electrode 14a and the second excitation electrode 14b are opposed to each other in the Y'-axis direction with the crystal piece 11 sandwiched therebetween. The first excitation electrode 14a is equivalent to an example of an "excitation electrode".

[0070] The first excitation electrode 14 has a rectangular planar shape having short sides extending in the Z'-axis direction and long sides extending in the X-axis direction. The first excitation electrode 14a has a thickness in the Y'-axis direction. The second excitation electrode 14b has the same shape.

[0071] In addition, the planar shape of the first excitation electrode and the second excitation electrode is not limited to the above. The planar shape of the first excitation electrode and the second excitation electrode may also be a rectangle having a short side extending in the X-axis direction. In addition, the planar shape of the first excitation electrode and the second excitation electrode may also be a square, a polygon, a circle, an ellipse, or a combination thereof.

[0072] The first extraction electrode 15a electrically connects the first excitation electrode 14a and the first connection electrode 16a, and the second extraction electrode 15b electrically connects the second excitation electrode 14b and the second connection electrode 16b. The first extraction electrode 15a is provided from the upper surface 11A to the lower surface 11B of the crystal piece 11, and the second extraction electrode 15b is provided on the lower surface 11B of the crystal piece 11.

[0073] The first connection electrode 16 a and the second connection electrode 16 b electrically connect the crystal resonator element 10 and the base member 30 . The first connection electrode 16 a and the second connection electrode 16 b are provided on the lower surface 11B of the crystal piece 11 .

[0074] The first excitation electrode 14a, the first extraction electrode 15a and the first connection electrode 16a are integrally arranged. The second excitation electrode 14b, the second extraction electrode 15b and the second connection electrode 16b are the same. The electrodes of these crystal vibration elements 10 are, for example, a multilayer structure in which a base layer and a surface layer are stacked in sequence. For example, the base layer is a chromium (Cr) layer with good adhesion to the crystal plate 11, and the surface layer is a gold (Au) layer with good chemical stability. The electrodes of the crystal vibration element 10 may also include titanium (Ti), aluminum (Al), molybdenum (Mo), or an aluminum-copper alloy (AlCu) with aluminum (Al) as the main component. The electrodes of the crystal vibration element 10 may also be a single-layer structure.

[0075] The mass-added film 20 reduces the acoustic velocity in a portion of the region where the first excitation electrode 14a and the second excitation electrode 14b face each other by a mass-added effect. The mass-added film 20 is provided on the side of the first excitation electrode 14a opposite to the crystal piece 11. At least a portion of the mass-added film 20 overlaps with the first excitation electrode 14a. The material of the mass-added film 20 is a conductor, for example, the same material as the first excitation electrode 14a.

[0076] When the first excitation electrode 14 a and the mass added film 20 are made of the same material and the boundary is unclear, the high acoustic velocity region 17 (see Figure 4 ) in the XZ′ plane including the surface of the first excitation electrode 14 a , a portion located on the opposite side to the crystal piece 11 is provided as the mass addition film 20 .

[0077] Furthermore, the mass addition film may be provided not on the side of the first excitation electrode opposite to the crystal piece, but on the side of the second excitation electrode opposite to the crystal piece 11. The material of the mass addition film 20 may be a metal different from that of the first excitation electrode or an insulator.

[0078] The base member 30 holds the crystal resonator element 10 so as to be excitable. The base member 30 includes a base 31, connection electrodes 33a and 33b, extraction electrodes 34a and 34b, external electrodes 35a, 35b, 35c and 35d, and conductive holding members 36a and 36b.

[0079] The substrate 31 is a plate-shaped insulator having an upper surface 31A and a lower surface 31B that are opposite to each other in the thickness direction. The upper surface 31A and the lower surface 31B are equivalent to a pair of main surfaces of the substrate 31. The upper surface 31A is located on the side opposite to the crystal vibration element 10 and the cover member 40, and is equivalent to the mounting surface on which the crystal vibration element 10 is mounted. From the viewpoint of suppressing the thermal stress acting on the crystal vibration element 10 from the substrate 31 due to thermal processes such as reflow soldering, it is preferred that the substrate 31 is composed of a heat-resistant material. From the same viewpoint, the substrate 31 can also be provided by a material having a thermal expansion coefficient close to that of the crystal piece 11. The substrate 31 is provided, for example, by a ceramic substrate, a glass substrate, or a crystal substrate.

[0080] The corner of the base 31 has a cut side surface whose part is formed into a cylindrical curved surface shape (also called a castellated shape). In addition, the shape of the corner of the base 31 is not limited to this. The corner of the base may also have a cut side surface formed into a prism shape, or may be a substantially right-angled corner without a cut.

[0081] The connection electrodes 33a and 33b are electrically connected to the crystal resonator element 10. The connection electrode 33a is electrically connected to the connection electrode 16a of the crystal resonator element 10, and the connection electrode 33b is connected to the connection electrode 16b of the crystal resonator element 10.

[0082] The lead electrode 34a electrically connects the connection electrode 33a and the external electrode 35a, and the lead electrode 34b electrically connects the connection electrode 33b and the external electrode 35b. The lead electrodes 34a and 34b are provided on the upper surface 31A of the base 31.

[0083] The external electrodes 35a and 35b are external terminals for electrically connecting the crystal resonator element 10 to an external substrate. The external electrode 35a electrically connects the first excitation electrode 14a of the crystal resonator element 10 to the mounting substrate 130, and the external electrode 35b electrically connects the second excitation electrode 14b of the crystal resonator element 10 to the mounting substrate 130. One of the external electrodes 35c and 35d is a grounding electrode for grounding the cover part 40, and the other is a dummy electrode that is not electrically connected to the crystal resonator element 10 and the cover part 40. The external electrodes 35a, 35b, 35c, and 35d are respectively provided continuously from the side faces of the cutouts provided at the four corners of the base 31 to the lower surface 31B. Figure 2In the example shown, the external electrode 35a and the external electrode 35b are located at opposite corners in the upper surface 31A of the substrate 31, and the external electrode 35c and the external electrode 35d are located at other opposite corners in the upper surface 31A of the substrate 31. Among them, the external electrodes 35a, 35b, 35c, and 35d are not limited to the above. The external electrodes 35c and 35d can both be ground electrodes or both be dummy electrodes. The external electrodes 35c and 35d can also be omitted. The external electrode 35c can also be electrically connected to one of the external electrodes 35a and 35b, and the external electrode 35d can also be electrically connected to the other of the external electrodes 35a and 35b.

[0084] The conductive holding parts 36a and 36b electrically connect the base part 30 and the crystal vibrating element 10, and mechanically hold the crystal vibrating element 10. The conductive holding part 36a electrically connects the first connection electrode 16a of the crystal vibrating element 10 and the connection electrode 33a of the base part 30. The conductive holding part 36b electrically connects the second connection electrode 16b of the crystal vibrating element 10 and the connection electrode 33b of the base part 30. The conductive holding parts 36a and 36b are cured products of a conductive adhesive including a thermosetting resin, a photocurable resin, or the like. The main component of the conductive holding parts 36a and 36b is, for example, a silicone resin. The conductive holding parts 36a and 36b contain conductive particles, and as the conductive particles, for example, metal particles containing silver (Ag) are used.

[0085] The main component of the conductive holding members 36a and 36b is not limited to silicone resin, and may be, for example, epoxy resin, acrylic resin, etc. In addition, the conductive particles contained in the conductive holding members 36a and 36b are not limited to silver particles, and may be formed of other metals, conductive ceramics, conductive organic materials, etc. The conductive holding members 36a and 36b may also contain conductive polymers.

[0086] The cover part 40 forms an internal space 39 for accommodating the crystal vibrating element 10 between the cover part 40 and the base part 30. The cover part 40 has a top wall part 41, a side wall part 42 extending from the outer edge of the top wall part 41 toward the base part 30, and a flange part 43 extending from the front end of the mounting substrate 130 toward the outside. The top wall part 41 is opposite to the base part 30 with the crystal vibrating element 10 sandwiched therebetween in the Y'-axis direction. The side wall part 42 surrounds the crystal vibrating element 10 at intervals in the XZ'-plane direction. The flange part 43 is set in a frame shape when viewed from above, and is set at a position closest to the base part 30 in the cover part 40. The material of the cover part 40 is preferably a conductive material, and more preferably a metal material with high airtightness. By making the cover part 40 of a conductive material, the cover part 40 is given an electromagnetic shielding function that reduces the entry and exit of electromagnetic waves into the internal space 39. From the viewpoint of suppressing the generation of thermal stress, the material of the cover member 40 is preferably a material having a thermal expansion coefficient close to that of the base member 30, for example, an Fe-Ni-Co alloy having a thermal expansion coefficient near room temperature consistent with that of glass and ceramics in a wide temperature range. The cover member 40 is electrically connected to at least one of the external electrodes 35c and 35d via a grounding member (not shown).

[0087] The joint 50 joins the base member 30 and the cover member 40 to seal the internal space 39. The joint 50 is provided in a frame shape over the entire circumference of the flange 43 of the base member 30, and is sandwiched between the lower surface of the flange 43 of the cover member 40 and the upper surface 31A of the base member 30. The joint 50 is provided by an insulating material. The joint 50 is provided by, for example, an organic adhesive including epoxy, vinyl, acrylic, polyurethane or silicone resins. The material of the joint 50 is not limited to an organic adhesive, and may also be provided by an inorganic adhesive such as a silicon adhesive including water glass or a calcium adhesive including cement. The material of the joint 50 may also be a low melting point glass (for example, a lead boric acid system, a tin phosphate system, etc.).

[0088] Next, refer to Figure 4 as well as Figure 5 , the structure of the crystal resonator element 10 according to the first embodiment is described. Figure 4 It is a cross-sectional view of the crystal resonator element according to the first embodiment. Figure 5 FIG. 1 is a top view of the crystal vibrating element of the first embodiment. Figure 4 as well as Figure 5 In the figure, the first extraction electrode 15a, the second extraction electrode 15b, the first connection electrode 16a, and the second connection electrode 16b are omitted.

[0089] The crystal resonator element 10 has a high sound velocity region 17, a low sound velocity region 18, and an outer high sound velocity region 19 in an excitation region excited by applying a voltage. The low sound velocity region 18 is a region where the sound velocity is reduced by the mass addition effect by providing a mass addition film 20. The sound velocities of the high sound velocity region 17 and the outer high sound velocity region 19 are greater than the sound velocity of the low sound velocity region 18. The sound velocity of the high sound velocity region 17 is substantially equal to the sound velocity of the outer high sound velocity region 19.

[0090] like Figure 5 As shown, the high acoustic velocity region 17 is provided in a region overlapping the center portion of the first excitation electrode 14a in a plan view. The planar shape of the high acoustic velocity region 17 is a rectangle having long sides extending in the X-axis direction and short sides extending in the Z'-axis direction.

[0091] In addition, the planar shape of the high sound velocity region is not limited to the above. The planar shape of the high sound velocity region may also be a rectangle having a short side extending along the X-axis direction and a long side extending along the Z'-axis direction. In addition, the planar shape of the high sound velocity region may also be a square, a polygon, a circle, an ellipse, or a combination thereof.

[0092] like Figure 5 As shown in FIG. 1 , the low sound velocity region 18 is provided in a region inside the outer edge of the first excitation electrode 14a and along the outer edge of the first excitation electrode 14a in a plan view. The low sound velocity region 18 is provided in a frame shape surrounding the central portion of the first excitation electrode 14a. The low sound velocity region 18 includes a first low sound velocity region 18A, a second low sound velocity region 18B, a third low sound velocity region 18C, and a fourth low sound velocity region 18D.

[0093] The first low sound velocity region 18A is adjacent to the negative Z'-axis side of the high sound velocity region 17 and extends along the X-axis direction. The second low sound velocity region 18B is adjacent to the positive Z'-axis side of the high sound velocity region 17 and extends along the X-axis direction. The third low sound velocity region 18C is adjacent to the positive X-axis side of the high sound velocity region 17 and extends along the Z'-axis direction. The fourth low sound velocity region 18D is adjacent to the negative X-axis side of the high sound velocity region 17 and extends along the Z'-axis direction. The end of the first low sound velocity region 18A on the positive X-axis side is connected to the end of the third low sound velocity region 18C on the negative Z'-axis side, and the end of the first low sound velocity region 18A on the negative X-axis side is connected to the end of the fourth low sound velocity region 18D on the negative Z'-axis side. The end of the second low acoustic velocity region 18B on the positive X-axis side is connected to the end of the third low acoustic velocity region 18C on the positive Z'-axis side, and the end of the second low acoustic velocity region 18B on the negative X-axis side is connected to the end of the fourth low acoustic velocity region 18D on the positive Z'-axis side.

[0094] In a plan view, the end of the first low acoustic velocity region 18A on the positive X-axis direction side overlaps with the end of the third low acoustic velocity region 18C on the negative Z'-axis direction side, and the end of the first low acoustic velocity region 18A on the negative X-axis direction side overlaps with the end of the fourth low acoustic velocity region 18D on the negative Z'-axis direction side. The end of the second low acoustic velocity region 18B on the positive X-axis direction side overlaps with the end of the third low acoustic velocity region 18C on the positive Z'-axis direction side, and the end of the second low acoustic velocity region 18B on the negative X-axis direction side overlaps with the end of the fourth low acoustic velocity region 18D on the positive Z'-axis direction side.

[0095] In a plan view, the outer edge portion of the first low acoustic velocity region 18A located on the side opposite to the central portion of the first excitation electrode 14a overlaps with the outer edge portion (outer edge portion 21A described later) located on the side opposite to the central portion of the first excitation electrode 14a in a first portion 21 described later of the mass addition film 20. The outer edge portion of the second low acoustic velocity region 18B located on the side opposite to the central portion of the first excitation electrode 14a overlaps with the outer edge portion (outer edge portion 22A described later) located on the side opposite to the central portion of the first excitation electrode 14a in a second portion 22 described later of the mass addition film 20. The outer edge portion of the third low acoustic velocity region 18C located on the side opposite to the central portion of the first excitation electrode 14a overlaps with the outer edge portion (outer edge portion 23A described later) located on the side opposite to the central portion of the first excitation electrode 14a in a third portion 23 described later of the mass addition film 20. The outer edge portion of the fourth low acoustic velocity region 18D located opposite to the center portion of the first excitation electrode 14a overlaps with the outer edge portion (outer edge portion 24A described later) of a fourth portion 24 of the mass addition film 20 located opposite to the center portion of the first excitation electrode 14a.

[0096] In a plan view, the inner edge portion of the first low acoustic velocity region 18A located on the central portion side of the first excitation electrode 14a overlaps with the inner edge portion (inner edge portion 21B described later) located on the central portion side of the first excitation electrode 14a in a first portion 21 described later of the mass addition film 20. The inner edge portion of the second low acoustic velocity region 18B located on the central portion side of the first excitation electrode 14a overlaps with the inner edge portion (inner edge portion 22B described later) located on the central portion side of the first excitation electrode 14a in a second portion 22 described later of the mass addition film 20. The inner edge portion of the third low acoustic velocity region 18C located on the central portion side of the first excitation electrode 14a overlaps with the inner edge portion (inner edge portion 23B described later) located on the central portion side of the first excitation electrode 14a in a third portion 23 described later of the mass addition film 20. The inner edge portion of the fourth low acoustic velocity region 18D located at the center of the first excitation electrode 14 a overlaps with the inner edge portion (inner edge portion 24B described later) of a fourth portion 24 of the mass addition film 20 located at the center of the first excitation electrode 14 a .

[0097] In a plan view, both the outer edge portion 71 of the first excitation electrode 14a, which will be described later, and the outer edge portion 81 of the second excitation electrode 14b, which will be described later, are farther from the center of the first excitation electrode 14a than the outer edge portion of the first low sound velocity region 18A. The outer edge portion 81 is farther from the center of the first excitation electrode 14a than the outer edge portion 71. Both the outer edge portion 72 of the first excitation electrode 14a, which will be described later, and the outer edge portion 82 of the second excitation electrode 14b, which will be described later, are farther from the center of the first excitation electrode 14a than the outer edge portion of the second low sound velocity region 18B. The outer edge portion 82 is farther from the center of the first excitation electrode 14a than the outer edge portion 72. Both the outer edge portion 73 of the first excitation electrode 14a, which will be described later, and the outer edge portion 83 of the second excitation electrode 14b, which will be described later, are farther from the center of the first excitation electrode 14a than the outer edge portion of the third low sound velocity region 18C. The outer edge portion 83 is farther from the center of the first excitation electrode 14a than the outer edge portion 73. The outer edge 74 of the first excitation electrode 14a and the outer edge 84 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the fourth low sound velocity region 18D. The outer edge 84 is farther from the center of the first excitation electrode 14a than the outer edge 74 is.

[0098] In addition, the shape of the low sound velocity region is not limited to the above. The third low sound velocity region and the fourth low sound velocity region may also be omitted. That is, the high sound velocity region, the first low sound velocity region and the second low sound velocity region may also be set as strips extending parallel to each other along the X-axis direction. In addition, the first low sound velocity region and the second low sound velocity region may also be omitted, and the high sound velocity region, the third low sound velocity region and the fourth low sound velocity region may be set as strips extending parallel to each other along the Z'-axis direction. In addition, the end of the first low sound velocity region on the positive direction side of the X-axis may also be separated from the third low sound velocity region, and the end of the first low sound velocity region on the negative direction side of the X-axis may also be separated from the fourth low sound velocity region. The end of the second low sound velocity region on the positive direction side of the X-axis may also be separated from the third low sound velocity region, and the end of the second low sound velocity region on the negative direction side of the X-axis may also be separated from the fourth low sound velocity region.

[0099] In addition, the positional relationship between the first low sound velocity region, the second low sound velocity region, the third low sound velocity region and the fourth low sound velocity region is not limited to the above. It is also possible that the first low sound velocity region is adjacent to the positive direction side of the Z' axis of the high sound velocity region, and the second low sound velocity region is adjacent to the negative direction side of the Z' axis of the high sound velocity region. It is also possible that the third low sound velocity region is adjacent to the negative direction side of the X axis of the high sound velocity region, and the fourth low sound velocity region is adjacent to the positive direction side of the X axis of the high sound velocity region. It is also possible that one of the first low sound velocity region and the second low sound velocity region is adjacent to the negative direction side of the X axis of the high sound velocity region, and the other is adjacent to the positive direction side of the X axis of the high sound velocity region. It is also possible that one of the third low sound velocity region and the fourth low sound velocity region is adjacent to the negative direction side of the Z' axis of the high sound velocity region, and the other is adjacent to the positive direction side of the Z' axis of the high sound velocity region.

[0100] like Figure 5 As shown in FIG. 1 , in a plan view, the outer high acoustic velocity region 19 is provided along the outer edge of the first excitation electrode 14a in a region between the outer edge of the mass added film 20 and the outer edge of the first excitation electrode 14a. The outer high acoustic velocity region 19 is provided in a frame shape surrounding the low acoustic velocity region 18. The outer high acoustic velocity region 19 includes a first outer high acoustic velocity region 19A, a second outer high acoustic velocity region 19B, a third outer high acoustic velocity region 19C, and a fourth outer high acoustic velocity region 19D.

[0101] The first outer high-acoustic velocity region 19A is adjacent to the negative Z'-axis side of the first low-acoustic velocity region 18A and extends along the X-axis direction. The second outer high-acoustic velocity region 19B is adjacent to the positive Z'-axis side of the second low-acoustic velocity region 18B and extends along the X-axis direction. The third outer high-acoustic velocity region 19C is adjacent to the positive X-axis side of the third low-acoustic velocity region 18C and extends along the Z'-axis direction. The fourth outer high-acoustic velocity region 19D is adjacent to the negative X-axis side of the fourth low-acoustic velocity region 18D and extends along the Z'-axis direction. The end of the first outer high-acoustic velocity region 19A on the positive X-axis side is connected to the end of the third outer high-acoustic velocity region 19C on the negative Z'-axis side, and the end of the first outer high-acoustic velocity region 19A on the negative X-axis side is connected to the end of the fourth outer high-acoustic velocity region 19D on the negative Z'-axis side. The end of the second outer high-acoustic velocity region 19B on the positive direction side of the X-axis is connected to the end of the third outer high-acoustic velocity region 19C on the positive direction side of the Z' axis, and the end of the second outer high-acoustic velocity region 19B on the negative direction side of the X-axis is connected to the end of the fourth outer high-acoustic velocity region 19D on the positive direction side of the Z' axis.

[0102] In a plan view, the end of the first outer high-acoustic velocity region 19A on the positive direction of the X axis overlaps with the end of the third outer high-acoustic velocity region 19C on the negative direction of the Z' axis, and the end of the first outer high-acoustic velocity region 19A on the negative direction of the X axis overlaps with the end of the fourth outer high-acoustic velocity region 19D on the negative direction of the Z' axis. The end of the second outer high-acoustic velocity region 19B on the positive direction of the X axis overlaps with the end of the third outer high-acoustic velocity region 19C on the positive direction of the Z' axis, and the end of the second outer high-acoustic velocity region 19B on the negative direction of the X axis overlaps with the end of the fourth outer high-acoustic velocity region 19D on the positive direction of the Z' axis.

[0103] In addition, the shape of the outer high-acoustic velocity region is not limited to the above. The third outer high-acoustic velocity region and the fourth outer high-acoustic velocity region may also be omitted. That is, the first outer high-acoustic velocity region and the second outer high-acoustic velocity region may also be set as a strip extending parallel to each other along the X-axis direction. At this time, the first outer high-acoustic velocity region and the second outer high-acoustic velocity region may also be set from the end of the first excitation electrode on the negative direction side of the X-axis to the end of the positive direction side of the X-axis when viewed from above. In addition, the first outer high-acoustic velocity region and the second outer high-acoustic velocity region may also be omitted, and the third outer high-acoustic velocity region and the fourth outer high-acoustic velocity region may be set as a strip extending parallel to each other along the Z'-axis direction. At this time, the third outer high-acoustic velocity region and the fourth outer high-acoustic velocity region may also be set from the end of the first excitation electrode on the negative direction side of the Z'-axis to the end of the positive direction side of the Z'-axis when viewed from above. In addition, the first outer high-acoustic velocity region may be separated from the third outer high-acoustic velocity region, or may be separated from the fourth outer high-acoustic velocity region. The second outer high-acoustic velocity region may be separated from the third outer high-acoustic velocity region, or may be separated from the fourth outer high-acoustic velocity region.

[0104] The crystal piece 11, the first excitation electrode 14a, and the second excitation electrode 14b are provided in the high acoustic velocity region 17, the low acoustic velocity region 18, and the outer high acoustic velocity region 19. A mass addition film 20 is further provided in the low acoustic velocity region 18. The mass addition film 20 is provided to avoid the high acoustic velocity region 17 and the outer high acoustic velocity region 19. That is, the planar shape of the mass addition film 20 is a frame shape overlapping the low acoustic velocity region 18.

[0105] The first excitation electrode 14a has outer edges 71, 72, 73, and 74. The outer edge 71 is an edge of one side extending along the X-axis on the negative Z'-axis side, among the four edges of the first excitation electrode 14a in a plan view. The outer edge 72 is an edge of one side extending along the X-axis on the positive Z'-axis side, the outer edge 73 is an edge of one side extending along the Z'-axis on the positive X-axis side, and the outer edge 74 is an edge of one side extending along the Z'-axis on the negative X-axis side.

[0106] The second excitation electrode 14b has outer edge portions 81, 82, 83, and 84. The outer edge portion 81 is an edge portion of one side extending along the X-axis on the negative Z'-axis direction side among the four edges of the second excitation electrode 14b in a plan view. The outer edge portion 82 is an edge portion of one side extending along the X-axis on the positive Z'-axis direction side, the outer edge portion 83 is an edge portion of one side extending along the Z'-axis on the positive X-axis direction side, and the outer edge portion 84 is an edge portion of one side extending along the Z'-axis on the negative X-axis direction side.

[0107] The mass added film 20 includes a first portion 21, a second portion 22, a third portion 23, and a fourth portion 24. The first portion 21 is provided on the first excitation electrode 14a in the first low acoustic velocity region 18A. The second portion 22 is provided on the first excitation electrode 14a in the second low acoustic velocity region 18B. The third portion 23 is provided on the first excitation electrode 14a in the third low acoustic velocity region 18C. The fourth portion 24 is provided on the first excitation electrode 14a in the fourth low acoustic velocity region 18D.

[0108] The first portion 21 avoids the high acoustic velocity region 17 and is provided along the outer edge 71 of the first excitation electrode 14a located on the negative side of the Z' axis in the high acoustic velocity region 17. The second portion 22 avoids the high acoustic velocity region 17 and is provided along the outer edge 72 of the first excitation electrode 14a located on the positive side of the Z' axis in the high acoustic velocity region 17. The third portion 23 avoids the high acoustic velocity region 17 and is provided along the outer edge 73 of the first excitation electrode 14a located on the positive side of the X axis in the high acoustic velocity region 17. The fourth portion 24 avoids the high acoustic velocity region 17 and is provided along the outer edge 74 of the first excitation electrode 14a located on the negative side of the X axis in the high acoustic velocity region 17. In a plan view, the first portion 21 is separated from the outer edge 71, the second portion 22 is separated from the outer edge 72, the third portion 23 is separated from the outer edge 73, and the fourth portion 24 is separated from the outer edge 74.

[0109] The first portion 21 includes an outer edge portion 21A located on the outer high-sonic velocity region 19 side, and an inner edge portion 21B located on the high-sonic velocity region 17 side. The second portion 22 includes an outer edge portion 22A located on the outer high-sonic velocity region 19 side, and an inner edge portion 22B located on the high-sonic velocity region 17 side. The third portion 23 includes an outer edge portion 23A located on the outer high-sonic velocity region 19 side, and an inner edge portion 23B located on the high-sonic velocity region 17 side. The fourth portion 24 includes an outer edge portion 24A located on the outer high-sonic velocity region 19 side, and an inner edge portion 24B located on the high-sonic velocity region 17 side.

[0110] The outer edge portions 21A, 22A, 23A, and 24A are located at the boundary between the low sound velocity region 18 and the outer high sound velocity region 19. The inner edge portions 21B, 22B, 23B, and 24B are located at the boundary between the high sound velocity region 17 and the low sound velocity region 18. The end portion of the outer edge portion 21A on the positive direction side of the X axis is connected to the end portion of the outer edge portion 23A on the negative direction side of the Z' axis, and the end portion of the outer edge portion 21A on the negative direction side of the X axis is connected to the end portion of the outer edge portion 24A on the negative direction side of the Z' axis. The end portion of the outer edge portion 22A on the positive direction side of the X axis is connected to the end portion of the outer edge portion 23A on the positive direction side of the Z' axis, and the end portion of the outer edge portion 22A on the negative direction side of the X axis is connected to the end portion of the outer edge portion 24A on the positive direction side of the Z' axis. The end of the inner edge portion 21B on the positive X-axis direction side is connected to the end of the inner edge portion 23B on the negative Z'-axis direction side, and the end of the inner edge portion 21B on the negative X-axis direction side is connected to the end of the inner edge portion 24B on the negative Z'-axis direction side. The end of the inner edge portion 22B on the positive X-axis direction side is connected to the end of the inner edge portion 23B on the positive Z'-axis direction side, and the end of the inner edge portion 22B on the negative X-axis direction side is connected to the end of the inner edge portion 24B on the positive Z'-axis direction side.

[0111] like Figure 5 As shown, in a plan view, the outer edges 71 and 72 of the first excitation electrode 14a overlap with the second excitation electrode 14b. The outer edges 71 and 72 of the first excitation electrode 14a are located between the outer edges 81 and 82 of the second excitation electrode 14b. The outer edge 71 of the first excitation electrode 14a is located between the outer edge 81 of the second excitation electrode 14b and the outer edge 21A of the first portion 21 of the mass addition film 20. The outer edge 72 of the first excitation electrode 14a is located between the outer edge 82 of the second excitation electrode 14b and the outer edge 22A of the second portion 22 of the mass addition film 20. Similarly, the outer edges 73 and 74 of the first excitation electrode 14a overlap with the second excitation electrode 14b. The outer edges 73 and 74 of the first excitation electrode 14a are located between the outer edges 83 and 84 of the second excitation electrode 14b. The outer edge 73 of the first excitation electrode 14a is located between the outer edge 83 of the second excitation electrode 14b and the outer edge 23A of the third portion 23 of the mass addition film 20. The outer edge 74 of the first excitation electrode 14a is located between the outer edge 84 of the second excitation electrode 14b and the outer edge 24A of the fourth portion 24 of the mass addition film 20.

[0112] like Figure 4As shown, the distance along the Z'-axis direction between the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 22A of the second portion 22 is set to length A. The distance along the Z'-axis direction between the inner edge 21B of the first portion 21 of the mass addition film 20 and the inner edge 22B of the second portion 22 is set to length A'. The distance along the Z'-axis direction between the outer edge 71 and the outer edge 72 of the first excitation electrode 14a is set to length B. The distance along the Z'-axis direction between the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 71 of the first excitation electrode 14a is set to length B1. The distance along the Z'-axis direction between the outer edge 22A of the second portion 22 of the mass addition film 20 and the outer edge 72 of the first excitation electrode 14a is set to length B2. The distance along the Z'-axis direction between the outer edge 81 and the outer edge 82 of the second excitation electrode 14b is set to length C. The distance along the Z'-axis direction between the outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b is defined as a length C1. The distance along the Z'-axis direction between the outer edge 72 of the first excitation electrode 14a and the outer edge 82 of the second excitation electrode 14b is defined as a length C2. The distance along the Z'-axis direction between the outer edge 21A and the inner edge 21B of the first portion 21 of the mass addition film 20 is defined as a length D1, and the distance along the Z'-axis direction between the outer edge 22A and the inner edge 22B of the second portion 22 of the mass addition film 20 is defined as a length D2. The distance along the Z'-axis direction between the outer edge of the first low acoustic velocity region 18A on the side opposite to the second low acoustic velocity region 18B and the outer edge of the second low acoustic velocity region 18B on the side opposite to the first low acoustic velocity region 18A is defined as a length E. The distance along the Z'-axis direction between the outer edge portion on the first low sound velocity region 18A side and the outer edge portion on the second low sound velocity region 18B side in the high sound velocity region 17 is set as the length E'. In other words, the length E' is the distance along the Z'-axis direction between the inner edge portion on the second low sound velocity region 18B side of the first low sound velocity region 18A and the inner edge portion on the first low sound velocity region 18A side of the second low sound velocity region 18B. The distance along the Z'-axis direction between the outer edge portion on the side opposite to the second low sound velocity region 18B in the first low sound velocity region 18A and the outer edge portion on the side of the second low sound velocity region 18B is set as the length E1. The distance along the Z'-axis direction between the outer edge portion on the side opposite to the first low sound velocity region 18A in the second low sound velocity region 18B and the outer edge portion on the side of the first low sound velocity region 18A is set as the length E2.

[0113] The length A corresponds to the dimension of the mass addition film 20 along the Z'-axis direction. The length A' corresponds to the dimension of the high acoustic velocity region 17 along the Z'-axis direction. The length B corresponds to the dimension of the first excitation electrode 14a along the Z'-axis direction, and corresponds to the sum of the dimensions of the high acoustic velocity region 17, the first low acoustic velocity region 18A, the second low acoustic velocity region 18B, the first outer high acoustic velocity region 19A, and the second outer high acoustic velocity region 19B along the Z'-axis direction. The length B1 corresponds to the dimension of the first outer high acoustic velocity region 19A along the Z'-axis direction, and the length B2 corresponds to the dimension of the second outer high acoustic velocity region 19B along the Z'-axis direction. The length C corresponds to the dimension of the second excitation electrode 14b along the Z'-axis direction. The length C1 corresponds to the dimension of the portion of the second excitation electrode 14b extending from the first excitation electrode 14a to the negative Z'-axis direction in a plan view along the Z'-axis direction. The length C2 corresponds to the dimension of the portion of the second excitation electrode 14b extending from the first excitation electrode 14a to the positive direction of the Z' axis in a plan view, along the Z' axis direction. The length D1 corresponds to the dimension of the first portion 21 of the mass addition film 20 along the Z' axis direction, and the length D2 corresponds to the dimension of the second portion 22 of the mass addition film 20 along the Z' axis direction. The length E corresponds to the sum of the dimensions of the high acoustic velocity region 17 and the low acoustic velocity region 18 along the Z' axis direction. The length E' corresponds to the dimension of the high acoustic velocity region 17 along the Z' axis direction. The length E1 corresponds to the dimension of the first low acoustic velocity region 18A along the Z' axis direction. The length E2 corresponds to the dimension of the second low acoustic velocity region 18B along the Z' axis direction.

[0114] like Figure 5 As shown, when the outer edges 21A and 22A of the mass adding membrane 20 are parallel to the X-axis direction in a plan view, the length A is determined by measuring the distance between the outer edges 21A and 22A in the Z'-axis direction. When the inner edges 21B and 22B of the mass adding membrane 20 are parallel to the X-axis direction in a plan view, the length A' is determined by measuring the distance between the inner edges 21B and 22B in the Z'-axis direction.

[0115] like Figure 5 As shown, when the outer edges 71 and 72 of the first excitation electrode 14a are parallel to the X-axis direction in a plan view, the length B is determined by measuring the distance in the Z'-axis direction between the outer edges 71 and the outer edges 72. When the outer edges 21A and 22A of the mass addition film 20 and the outer edges 71 and 72 of the first excitation electrode 14a are parallel to the X-axis direction in a plan view, the length B1 is determined by measuring the distance in the Z'-axis direction between the outer edge 21A and the outer edge 71, and the length B2 is determined by measuring the distance in the Z'-axis direction between the outer edge 22A and the outer edge 72.

[0116] like Figure 5 As shown, when the outer edges 81 and 82 of the second excitation electrode 14b are parallel to the X-axis direction in a plan view, the length C is determined by measuring the distance between the outer edges 81 and 82 in the Z'-axis direction. When the outer edges 71 and 72 of the first excitation electrode 14a and the outer edges 81 and 82 of the second excitation electrode 14b are parallel to the X-axis direction in a plan view, the length C1 is determined by measuring the distance between the outer edges 71 and 81 in the Z'-axis direction, and the length C2 is determined by measuring the distance between the outer edges 72 and 82 in the Z'-axis direction.

[0117] like Figure 5 As shown, when the outer edge portions 21A, 22A and the inner edge portions 21B, 22B of the mass addition membrane 20 are parallel to the X-axis direction when viewed from above, the length D1 is determined by measuring the distance between the outer edge portion 21A and the inner edge portion 21B in the Z'-axis direction, and the length D2 is determined by measuring the distance between the outer edge portion 22A and the inner edge portion 22B in the Z'-axis direction.

[0118] like Figure 5 As shown, when the outer edges 21A, 22A and the inner edges 21B, 22B of the mass added film 20 are parallel to the X-axis direction when viewed from above, the length E is determined by measuring the distance between the outer edge 21A and the outer edge 22A in the Z'-axis direction. In addition, the length E' is determined by measuring the distance between the inner edge 21B and the inner edge 22B in the Z'-axis direction, the length E1 is determined by measuring the distance between the outer edge 21A and the inner edge 21B in the Z'-axis direction, and the length E2 is determined by measuring the distance between the outer edge 22A and the inner edge 22B in the Z'-axis direction.

[0119] In the case where the planar shape of the mass adding film 20 is a polygonal shape, a circular shape, an elliptical shape or a combination thereof, and the outer edges 21A and 22A of the mass adding film 20 are not parallel when viewed from above, the length A is determined by a method other than the above. For example, the length A may be determined as the maximum value of the distance between the outer edge 21A and the outer edge 22A. The length A may be determined as the average value or the minimum value of the distance between the outer edge 21A and the outer edge 22A. In addition, the length A may be determined by dividing the area of ​​the area enclosed by the outer edges 21A, 22A, 23A, and 24A of the mass adding film 20 by the distance in the X-axis direction between the outer edge 23A and the outer edge 24A. In addition, the length A may be determined by measuring the distance between the outer edge 21A and the outer edge 22A on a tangent extending in the Z'-axis direction tangent to the inner edge 23B or the inner edge 24B of the mass adding film 20 when viewed from above. The lengths A′, B, B1, B2, C, C1, C2, D1, D2, E, E′, E1, and E2 can also be determined in the same manner as the length A.

[0120] In the present embodiment, the length E is substantially equal to the length A (E=A), and the length E' is substantially equal to the length A' (E'=A'). The length E1 is substantially equal to the length D1 (E1=D1), and the length E2 is substantially equal to the length D2 (E2=D2). The length E1 is substantially equal to the length E2 (E1=E2). Specifically, the relationship E1=E2=(1±0.04)×(E-E') / 2 holds. The length E1 and the length E2 are greater than the length A' (A'<E1, and A'<E2). Among them, the length E1 and the length E2 may be substantially equal to the length A', or may be smaller than the length A'.

[0121] In the present embodiment, length A is smaller than length B, and length B is smaller than length C (A<B<C). Length B1 is approximately equal to length B2 (B1=B2). Specifically, the relationship B1=B2=(1±0.10)×(BA) / 2 holds. Length C1 is approximately equal to length C2 (C1=C2). Specifically, the relationship C1=C2=(1±0.10)×(CB) / 2 holds. As an example, length C1 is larger than length B1 (B1<C1), and length C2 is larger than length B2 (B2<C2). Length D1 is approximately equal to length D2 (D1=D2). Specifically, the relationship D1=D2=(1±0.04)×(A-A') / 2 holds. As an example, length D1 is greater than length A' (A'≤D1), and length D2 is greater than length A' (A'≤D2). The ratio A' / B of the length A' to the length B is, for example, 0.02 or more (0.02 ≤ A' / B). Preferably, the relationship of 0.05 ≤ A' / B ≤ 0.5 holds. More preferably, the relationship of 0.20 ≤ A' / B ≤ 0.47 holds.

[0122] In addition, if the relationship A<B<C holds, the size relationship of the lengths A, A', B, B1, B2, C, C1, C2, D1, and D2 is not limited to the above. For example, the relationship B1<B2 or B2<B1 may also hold, and the relationship C1<C2 or C2<C1 may also hold. The relationship C1≤B1 may also hold, and the relationship C2≤B2 may also hold. The relationship D1<D2 or D2<D1 may also hold. The relationship D1<A' may also hold, and the relationship D2<A' may also hold.

[0123] like Figure 4 As shown, the thickness of the crystal piece 11 is set to Tp, the thickness of the first excitation electrode 14a is set to Te1, the thickness of the second excitation electrode 14b is set to Te2, and the thickness of the mass addition film 20 is set to Tf. In the case where the first excitation electrode 14a and the mass addition film 20 are made of the same material and the boundary is not clear, the thickness Tf of the mass addition film 20 may be determined as the distance along the Y'-axis direction between the surface of the first excitation electrode 14a in the high acoustic velocity region 17 and the surface of the mass addition film 20 in the low acoustic velocity region 18. In addition, the thickness Tf of the mass addition film 20 may be determined as the height of the step difference in the outer edge portions 21A, 22A, 23A, and 24A of the mass addition film 20, or may be determined as the height of the step difference in the inner edge portions 21B, 22B, 23B, and 24B of the mass addition film 20. When the height of the step difference in the outer edge portions 21A, 22A, 23A, and 24A is different from the height of the step difference in the inner edge portions 21B, 22B, 23B, and 24B, the thickness Tf of the mass addition film 20 is determined to be the height of the step difference in the inner edge portions 21B, 22B, 23B, and 24B.

[0124] The thickness Tp is substantially constant throughout the high-acoustic velocity region 17, the low-acoustic velocity region 18, and the outer high-acoustic velocity region 19. Similarly, the thicknesses Te1 and Te2 are substantially constant throughout the high-acoustic velocity region 17, the low-acoustic velocity region 18, and the outer high-acoustic velocity region 19. The thickness Tf is substantially constant throughout the entire low-acoustic velocity region 18. That is, the thicknesses of the first portion 21, the second portion 22, the third portion 23, and the fourth portion 24 are substantially equal. The thickness Te1 is substantially equal to the thickness Te2 (Te1=Te2), and the thickness Tf is smaller than the thickness Te1 (Tf<Te1). For example, the thicknesses Te1 and Te2 are approximately 0.05 μm, and the thickness Tf is approximately 0.02 μm.

[0125] In addition, the relationship between the thicknesses is not limited to the above. For example, the thickness Tf may be equal to or greater than the thickness Te1 (Te1≤Tf). The thickness Te1 may be smaller than the thickness Te2 (Te1<Te2), or the thickness Te1 may be larger than the thickness Te2 (Te2<Te1).

[0126] like Figure 5As shown, the dimension of the crystal piece 11 along the X-axis direction is set to length Px, and the dimension of the crystal piece 11 along the Z'-axis direction is set to length Pz. The dimension of the first excitation electrode 14a along the X-axis direction is set to length Xe1, and the dimension of the first excitation electrode 14a along the Z'-axis direction is set to length Ze1. The dimension of the second excitation electrode 14b along the X-axis direction is set to length Xe2, and the dimension of the second excitation electrode 14b along the Z'-axis direction is set to length Ze2. The distance along the Z'-axis direction between the outer edge portion 21A of the first portion 21 of the mass addition film 20 and the outer edge portion 71 of the first excitation electrode 14a is set to length Wgz. The distance along the Z'-axis direction between the outer edge portion 22A of the second portion 22 of the mass addition film 20 and the outer edge portion 72 of the first excitation electrode 14a is set to length Wgz. The distance along the Z'-axis direction between the inner edge portion 21B of the first portion 21 of the mass addition film 20 and the outer edge portion 71 of the first excitation electrode 14a is set to length Wz. The distance along the Z'-axis direction between the inner edge 22B of the second portion 22 of the mass addition film 20 and the outer edge 72 of the first excitation electrode 14a is defined as a length Wz. The distance along the X-axis direction between the outer edge 23A of the third portion 23 of the mass addition film 20 and the outer edge 73 of the first excitation electrode 14a is defined as a length Wgx. The distance along the X-axis direction between the outer edge 24A of the fourth portion 24 of the mass addition film 20 and the outer edge 74 of the first excitation electrode 14a is defined as a length Wgx. The distance along the X-axis direction between the inner edge 23B of the third portion 23 of the mass addition film 20 and the outer edge 73 of the first excitation electrode 14a is defined as a length Wx. The distance along the X-axis direction between the inner edge 24B of the fourth portion 24 of the mass addition film 20 and the outer edge 74 of the first excitation electrode 14a is defined as a length Wx. The distance between the first portion 21 and the second portion 22 of the mass addition film 20 along the Z′ axis direction is defined as a length Zf, and the distance between the third portion 23 and the fourth portion 24 of the mass addition film 20 along the X axis direction is defined as a length Xf.

[0127] The length Ze2 corresponds to the length C (Ze2=C). The length Ze1 corresponds to the length B (Ze1=B). The length Wgz corresponds to the lengths B1 and B2 (Wgz=B1=B2). The length Wz corresponds to the sum of the length B1 and the length D1, and the sum of the length B2 and the length D2 (Wz=B1+D1=B2+D2). The length Zf corresponds to the length A' (Zf=A'). The dimension of the mass addition film 20 along the Z'-axis direction can be expressed as 2×Wz+Zf-2×Wgz, which is less than or equal to the dimension Ze2 of the second excitation electrode 14b along the Z'-axis direction (2×Wz+Zf-2×Wgz≤Ze2). In addition, the dimension of the mass addition film 20 along the X-axis direction can be expressed as 2×Wx+Xf-2×Wgx, which is less than or equal to the dimension Xe2 of the second excitation electrode 14b along the X-axis direction (2×Wx+Xf-2×Wgx≤Xe2). The length Wgz is, for example, substantially equal to the length Wgx (Wgz=Wgx). However, the length Wgz may be smaller than the length Wgx (Wgz<Wgx), or the length Wgz may be larger than the length Wgx (Wgx<Wgz).

[0128] Next, refer to Figures 6 to 16 , simulation results based on an example of the first embodiment are described. Figure 6 This is a table showing the conditions of the simulation based on the first embodiment. Figures 7 to 16 It is a graph showing the simulation results based on the first embodiment.

[0129] (First embodiment)

[0130] Tp=1.52μm

[0131] Tf=0.02μm

[0132] Te1=Te2=0.08μm

[0133] Px=Pz=120μm

[0134] Xf=Zf=20μm

[0135] Wx=40μm

[0136] Wz=30μm

[0137] Wgx: Variable

[0138] Wgz: Variable

[0139] Xe1=100μm

[0140] Ze1=80μm

[0141] Xe2=104μm Ze2=84μm

[0142] (First embodiment)

[0143] Wgx=Wgz=2μm Xe2:variable

[0144] Ze2: Variables other than the above are the same as those in the first embodiment.

[0145] (Second embodiment)

[0146] Tp=1.00μm

[0147] Tf=0.02μm

[0148] Te1=Te2=0.05μm

[0149] Px=Pz=100μm

[0150] Xf=12μm

[0151] Zf=28μm

[0152] Wx=24μm Wz=16μm Wgx:variable

[0153] Wgz: Variable

[0154] Xe1=Ze1=60μm Xe2=Ze2=64μm (Second Embodiment)

[0155] Wgx=Wgz=2μm Xe2:variable

[0156] Ze2: Variables other than the above are the same as those of the second embodiment.

[0157] (Third Embodiment)

[0158] Tp=1.00μm

[0159] Tf=0.02μm

[0160] Te1=Te2=0.05μm

[0161] Px=Pz=100μm

[0162] Xf=19μm

[0163] Zf=30μm

[0164] Wx=28μm

[0165] Wz=20μm

[0166] Wgx: Variable

[0167] Wgz: Variable

[0168] Xe1=75μm

[0169] Ze1=70μm

[0170] Xe2=79μm

[0171] Ze2=74μm

[0172] (Third Embodiment)

[0173] Wgx=Wgz=2μm

[0174] Xe2: Variable

[0175] Ze2: Variables

[0176] The other aspects are the same as those of the third embodiment.

[0177] Figure 7 Represents the simulation results based on the first embodiment. The vertical axis represents the electromechanical coupling coefficient k (hereinafter also referred to as "k_S0") of the S0 mode as the main mode, and the horizontal axis represents Wgx=Wgz. In the graph, the simulation results of k_S0 in the first embodiment (Wx=40μm, Wz=30μm), the simulation results of k_S0 in the structure based on the first embodiment and changed to Wx=30μm, Wz=25μm, and the simulation results of k_S0 in the structure based on the first embodiment and changed to Wx=25μm, Wz=20μm are depicted. In the case of Tf=0, that is, the structure without the mass addition film 20, k_S0 is about 6.8%. In addition, Xf and Zf are determined by the following formulas Xf=Xe1-Wx×2, Zf=Ze1-Wz×2, so Xf and Zf change in conjunction with Wx and Wz.

[0178] In the first embodiment, when B'=Wgx=Wgz≤8μm, k_S0 is improved from 6.8% in the case of Tf=0. According to the structure of the first embodiment, even if Wx and Wz are changed, the same trend is obtained. At least when the ratio of Wx to Xe1 is 25% or more and 40% or less, and the ratio of Wz to Ze1 is 25% or more and 37.5% or less, regardless of the size of Wx and Wz, when B'=Wgx=Wgz<8μm, 6.8%<k_S0 is achieved, and when B'=Wgx=Wgz≤7μm, 6.8%<k_S0 is achieved.

[0179] In addition, when the plane shape of the mass addition film is a rectangular frame shape that is continuous in the circumferential direction, the condition that 6.8% < k_S0 is achieved when B' = Wgx = Wgz < 8 μm regardless of the size of Wx and Wz is expressed by the area ratio of the mass addition film to the area of ​​the first excitation electrode, and the area ratio is 75% or more and 95% or less. In addition, when the plane shape of the mass addition film is two strips parallel to the X-axis direction, the condition that 6.8% < k_S0 is achieved when B' = Wgz < 8 μm regardless of the size of Wz means that the area ratio is 50% or more and 80% or less. Similarly, when the plane shape of the mass addition film is two strips parallel to the Z'-axis direction, the condition that 6.8% < k_S0 is achieved when B' = Wgx < 8 μm regardless of the size of Wx means that the area ratio is 50% or more and 80% or less.

[0180] Figure 8 The simulation results based on the first embodiment are shown. Fig. 9 The simulation results based on the second embodiment are shown in FIG. Figure 8 as well as Fig. 9 In FIG. 1 , the vertical axis represents the electromechanical coupling coefficient k (hereinafter also referred to as “k_A0”) of the A0 mode which is a parasitic mode, and the horizontal axis represents Wgx=Wgz. Figure 8 as well as Fig. 9 The graphs of show the simulation results of k_A0Z in the structure where the mass addition film 20 and the second excitation electrode 14b are not misaligned, and the simulation results of k_A0Z in the structure where the mass addition film 20 and the second excitation electrode 14b are misaligned. The simulation results of k_A0Z in the structure where the mass addition film 20 and the second excitation electrode 14b are misaligned by 0.5 μm in the positive direction of the X axis and the positive direction of the Z' axis, and the simulation is performed on the assumption that the mass addition film 20 is misaligned by 0.5 μm in the positive direction of the X axis and the positive direction of the Z' axis, and the second excitation electrode 14b is misaligned by 0.5 μm in the negative direction of the X axis and the negative direction of the Z' axis.

[0181] exist Figure 8 as well as Fig. 9 In the range of 2μm≤B'=Wgx=Wgz≤10μm, k_A0Z in the structure with positional displacement and k_A0Z in the structure without positional displacement are substantially equal. That is, in the range of 2μm≤B'=Wgx=Wgz≤10μm, the increase of k_A0Z is suppressed regardless of the size and positional displacement of the first excitation electrode 14a, the second excitation electrode 14b, and the mass addition film 20.

[0182] Fig.10The graph shows simulation results based on the first embodiment. The vertical axis shows Q value, and the horizontal axis shows Wgx=Wgz. The graph shows simulation results of Q value in a structure without positional misalignment of the mass addition film 20 and the second excitation electrode 14 b , and simulation results of Q value in a structure with positional misalignment. Fig.10 The direction and amount of the positional offset in the structure with positional offset are related to Figure 8 as well as Fig. 9 The direction and amount of the positional offset in the structure with positional offset are the same.

[0183] In the structure without positional shift, the Q value does not change substantially in the range of 0<B'=Wgx=Wgz≤10μm. In addition, the Q value in the structure with positional shift is substantially equal to the Q value in the structure without positional shift. That is, regardless of the size of B'=Wgx=Wgz and the presence or absence of positional shift, the Q value is substantially constant.

[0184] Fig.11 The figure shows the simulation results based on the first embodiment. The vertical axis represents k_S0 and the horizontal axis represents x=CB=Ze2-Ze1. The figure shows the simulation results of k_S0 in the structure where the mass addition film 20 and the second excitation electrode 14b are not misaligned and the simulation results of k_S0 in the structure where the mass addition film 20 and the second excitation electrode 14b are misaligned. Fig.11 The direction and amount of the positional offset in the structure with positional offset are related to Figure 8 as well as Fig. 9 The direction and amount of the positional offset in the structure with positional offset are the same.

[0185] In the structure without positional shift, k_S0 does not change substantially in the range of 0<x≤10μm. In addition, in the range of 0<x≤10μm, k_S0 in the structure with positional shift is substantially equal to k_S0 in the structure without positional shift. That is, k_S0 is substantially constant regardless of the size of x and the presence or absence of positional shift.

[0186] Fig.12 represents the simulation results based on the first embodiment, Fig.13 represents the simulation results based on the second embodiment, Fig.14 Figure 2 shows the simulation results based on the third embodiment. Figure 12 to Figure 14 In the figure, the vertical axis represents k_A0 and the horizontal axis represents x=CB=Ze2-Ze1. Figure 12 to Figure 14 The graph of shows the simulation results of k_A0X and k_A0Z in the structure where the mass addition film 20 and the second excitation electrode 14 b are not misaligned and the simulation results of k_A0X and k_A0Z in the structure where the mass addition film 20 and the second excitation electrode 14 b are misaligned. Figure 12 to Figure 14 The direction and amount of the positional offset in the structure with positional offset are related to Figure 8 as well as Fig. 9 The direction and amount of the positional offset in the structure with positional offset are the same.

[0187] exist Fig.12 In the range of 3μm≤x≤10μm, k_A0X and k_A0Z are sufficiently reduced and roughly constant. That is, in the range of 3μm≤x≤10μm, the excitation suppression effect of the A0 mode is stable. In addition, in the range of 3μm≤x≤10μm, k_A0X and k_A0Z in the structure with positional offset are roughly equal to k_A0X and k_A0Z in the structure without positional offset. That is, in the range of 3μm≤x≤10μm, regardless of the size of x and the presence or absence of positional offset, k_A0X and k_A0Z are roughly constant. Fig.13 as well as Fig.14 In , k_A0X and k_A0Z show the same tendency. That is, regardless of the size and positional deviation of the first excitation electrode 14a, the second excitation electrode 14b, and the mass addition film 20, the increase of k_A0 is suppressed.

[0188] Fig.15 as well as Fig.16 Shows the simulation results based on the first embodiment. Fig.15 as well as Fig.16 In the figure, the vertical axis represents the Q value, and the horizontal axis represents x=CB=Ze2-Ze1. Fig.15 The graph of shows the simulation results of the Q value in a structure where there is no positional misalignment between the mass adding film 20 and the second excitation electrode 14 b and the simulation results of the Q value in a structure where there is a positional misalignment between the mass adding film 20 and the second excitation electrode 14 b. Fig.15 The direction and amount of the positional offset in the structure with positional offset are related to Figure 8 as well as Fig. 9 The direction and amount of the positional offset in the structure with positional offset are the same. Fig.16 The chart depicts the simulation results of the Q value in the first embodiment (Wx=40μm, Wz=30μm), the simulation results of the Q value in the structure changed to Wx=30μm, Wz=25μm based on the first embodiment, and the simulation results of the Q value in the structure changed to Wx=45μm, Wz=30μm based on the first embodiment.

[0189] like Fig.15 As shown, the Q value in the structure without positional shift is 80% or more of the Q value in the case of x = 0 μm in the range of 0<x≤8μm. The Q value in the structure with positional shift shows the same trend as the Q value in the structure without positional shift and is substantially equal to the Q value in the structure without positional shift. That is, in the range of 0<x≤8μm, the decrease in Q value is suppressed regardless of the presence or absence of positional shift.

[0190] like Fig.16 As shown, when Wx and Wz are changed based on the first embodiment, the Q value shows the same tendency. That is, in the range of 0<x≤8 μm, the decrease in the Q value is suppressed regardless of the sizes of the first excitation electrode 14 a , the second excitation electrode 14 b , and the mass adding film 20 .

[0191] Next, refer to Fig.17 as well as Fig.18 , the influence of position offset is explained. Fig.17 This is a diagram for explaining the influence of positional deviation in the first embodiment. Fig.18 This is a diagram for explaining the influence of positional deviation in the first embodiment. Fig.17 1 is a cross-sectional view of the crystal resonator element 10 when the mass addition film 20 is shifted by dz in the positive direction of the Z′ axis. Fig.18 1 is a cross-sectional view of the crystal resonator element 10 when the second excitation electrode 14 b is offset by dz in the negative direction of the Z′ axis.

[0192] like Fig.17 As shown in FIG. 1 , when the length of the first outer high-acoustic-velocity region 19A along the Z'-axis direction when the mass addition film 20 is offset by dz in the positive direction of the Z'-axis is set to B1d1, the length B1d1 is greater than the length B1 by an amount corresponding to the offset dz. That is, it is expressed as B1d1=B1+dz. When the length of the second outer high-acoustic-velocity region 19B along the Z'-axis direction when the mass addition film 20 is offset by dz in the positive direction of the Z'-axis is set to B2d1, the length B2d1 is smaller than the length B2 by an amount corresponding to the offset dz. That is, it is expressed as B2d1=B2-dz.

[0193] like Fig.17 As shown, when the length of the first low acoustic velocity region 18A along the Z'-axis direction when the mass addition film 20 is offset by dz in the positive direction of the Z'-axis is set to E1d1, the length E1d1 does not change from the length E1. That is, it is expressed as E1d1=E1=D1. When the length of the second low acoustic velocity region 18B along the Z'-axis direction when the mass addition film 20 is offset by dz in the positive direction of the Z'-axis is set to E2d1, the length E2d1 does not change from the length E2. That is, it is expressed as E2d1=E2=D2. Therefore, in the present embodiment, when the mass addition film 20 is offset by dz in the positive direction of the Z'-axis, the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z'-axis direction does not change, and the relationship of E1d1=E2d1 holds. Therefore, even if the mass addition film 20 is offset by dz in the positive direction of the Z'-axis, the increase of k_A0 is suppressed and the decrease of k_S0 is suppressed.

[0194] In addition, when B2<dz, the second portion 22 of the mass addition film 20 extends from the first excitation electrode 14a to the positive direction of the Z' axis when viewed from above. Therefore, a portion of the second portion 22 of the mass addition film 20 that does not overlap with the first excitation electrode 14a appears, and the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis direction changes. In order to maintain the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis direction, it is preferable to satisfy the relationship dz≤B'=B1=B2. The positional offset in the same plane is, for example, about 0.3 μm at most, so it is preferably 0.5 μm≤B', more preferably 1 μm≤B', and even more preferably 2 μm≤B'.

[0195] like Fig.18 As shown, when the length of the first low acoustic velocity region 18A along the Z' axis direction when the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis is set to E1d2, the length E1d2 does not change from the length E1. That is, it is expressed as E1d2=E1=D1. When the length of the second low acoustic velocity region 18B along the Z' axis direction when the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis is set to E2d2, the length E2d2 does not change from the length E2. That is, it is expressed as E2d2=E2=D2. Therefore, in this embodiment, when the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis, the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis direction does not change, and the relationship of E1d2=E2d2 holds. Therefore, even if the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis, the increase of k_A0 is suppressed and the decrease of k_S0 is suppressed.

[0196] In addition, when C2<dz, the second excitation electrode 14b extends from the first excitation electrode 14a to the positive direction of the Z' axis when viewed from above. Therefore, in the first excitation electrode 14a, a portion that does not overlap with the second excitation electrode 14b appears, and the balance of the lengths of the first outer high-acoustic velocity region 19A and the second outer high-acoustic velocity region 19B along the Z' axis direction changes. In order to maintain the balance of the lengths of the first outer high-acoustic velocity region 19A and the second outer high-acoustic velocity region 19B along the Z' axis direction, it is preferred to satisfy the relationship dz≤C'=C1=C2. The positional offset in different planes is, for example, up to about 0.7μm, so it is preferably 1μm≤C', more preferably 2μm≤C', and even more preferably 4μm≤C'.

[0197] As described above, according to the present embodiment, the mass adding film 20 is provided on the first excitation electrode 14a. The mass adding film 20 is provided along the outer edge of the first excitation electrode 14a, and when the dimension of the mass adding film 20 along the Z'-axis direction is A and the dimension of the second excitation electrode 14b along the Z'-axis direction is C, the relationship A≤C holds. In addition, the outer edge 21A of the first portion 21 and the outer edge 22A of the second portion 22 of the mass adding film 20 overlap with the second excitation electrode 14b.

[0198] Thus, even when the mass added film 20 and the second excitation electrode 14b are misaligned, the deterioration of the balance of the dimensions of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B can be suppressed. Therefore, the increase of the electromechanical coupling coefficient k_A0 of the parasitic mode can be suppressed, and the decrease of the electromechanical coupling coefficient k_S0 of the main mode can be suppressed.

[0199] In addition, in the present embodiment, when the dimension of the first portion 21 of the mass addition film 20 along the Z'-axis direction is set to D1, the dimension of the second portion 22 of the mass addition film 20 along the Z'-axis direction is set to D2, and the distance between the first portion 21 and the second portion 22 of the mass addition film 20 along the Z'-axis direction is set to A, D1 and D2 are approximately equal, for example, D1 = (1±0.04) × (A-A') / 2μm, D2 = (1±0.04) × (A-A') / 2μm.

[0200] Thereby, parasitic oscillation in the A0 mode can be suppressed.

[0201] In the present embodiment, when A′ is the distance between the first portion 21 and the second portion 22 of the mass addition film 20 along the Z′ axis direction and B is the dimension of the first excitation electrode 14 a along the Z′ axis direction, the relationship A′ / B≦0.5 holds.

[0202] This can prevent the effect of reducing the parasitic oscillation by the mass addition film 20 from being reduced due to the area of ​​the first portion 21 or the second portion 22 of the mass addition film 20 being too large.

[0203] In addition, in the present embodiment, the relationship of 0.05≤A′ / B holds.

[0204] Thus, when the mass adding film 20 is displaced relative to the first excitation electrode 14a, most of the first portion 21 or the second portion 22 of the mass adding film 20 is prevented from extending outward from the first excitation electrode 14a in a plan view. That is, it is possible to prevent the deterioration of the balance of the dimensions of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B. Therefore, it is possible to sufficiently prevent an increase in k_A0 and a decrease in k_S0.

[0205] In addition, in this embodiment, when the distance along the Z'-axis direction between the outer edge portion 21A of the first portion 21 of the mass addition film 20 and the outer edge portion 71 of the first excitation electrode 14a, and the distance along the Z'-axis direction between the outer edge portion 22A of the second portion 22 of the mass addition film 20 and the outer edge portion 72 of the first excitation electrode 14a are set to B', the relationship of 2μm≤B' holds.

[0206] This can suppress the increase in k_A0.

[0207] In addition, in the present embodiment, the relationship of B'≤8 μm holds.

[0208] This can suppress a decrease in k_S0.

[0209] In the present embodiment, when the dimension of the second excitation electrode 14 b along the Z′-axis direction is represented by C, a relationship of 3 μm≦CB holds.

[0210] This can suppress an increase in k_A0.

[0211] In addition, in the present embodiment, the relationship of CB ≤ 10 μm holds.

[0212] This can suppress a decrease in the Q value.

[0213] Other embodiments are described below. In addition, the same or similar reference numerals are used for structures that are the same or similar to those shown in the first embodiment, and their description is appropriately omitted. In addition, the same effects based on the same structure are not mentioned in sequence.

[0214] <Second embodiment>

[0215] Next, refer to Fig.19 , the structure of the crystal resonator element 210 according to the second embodiment is described. Fig.19 It is a cross-sectional view of the crystal resonator element according to the second embodiment.

[0216] In a plan view, the outer edge 71 of the first excitation electrode 14a overlaps with the outer edge 81 of the second excitation electrode 14b, and the outer edge 72 of the first excitation electrode 14a overlaps with the outer edge 82 of the second excitation electrode 14b. The outer edge 21A of the first portion 21 and the outer edge 22A of the second portion 22 of the mass addition film 20 are located between the outer edge 71 and the outer edge 72 of the first excitation electrode 14a. The length B is substantially equal to the length C and is greater than the length A (A<B=C). The length E1 is substantially equal to the length D1 (E1=D1), the length E1 is substantially equal to the length D1 (E2=D2), and the length E1 is substantially equal to the length E2 (E1=E2).

[0217] In a plan view, the outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the first low sound velocity region 18A. The outer edge 71 and the outer edge 81 are equally spaced from the center of the first excitation electrode 14a. The outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the second low sound velocity region 18B. The outer edge 72 and the outer edge 82 are equally spaced from the center of the first excitation electrode 14a.

[0218] <Third embodiment>

[0219] Next, refer to Fig. 20 , the structure of the crystal resonator element 310 according to the third embodiment is described. Fig. 20 It is a cross-sectional view of a crystal resonator element according to the third embodiment.

[0220] In a plan view, the outer edge 81 of the second excitation electrode 14b is located between the outer edge 71 of the first excitation electrode 14a and the outer edge 21A of the first portion 21 of the mass addition film 20. The outer edge 82 of the second excitation electrode 14b is located between the outer edge 72 of the first excitation electrode 14a and the outer edge 22A of the second portion 22 of the mass addition film 20. The outer edge 21A of the first portion 21 and the outer edge 22A of the second portion 22 of the mass addition film 20 are located between the outer edge 81 and the outer edge 82 of the second excitation electrode 14b. The outer edge 81 and the outer edge 82 of the second excitation electrode 14b are located between the outer edge 71 and the outer edge 72 of the first excitation electrode 14a. The length B is greater than the length C, and the length C is greater than the length A (A<C<B). The length E1 is substantially equal to the length D1 (E1=D1), the length E1 is substantially equal to the length D1 (E2=D2), and the length E1 is substantially equal to the length E2 (E1=E2).

[0221] In a plan view, both the outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b are farther from the center of the first excitation electrode 14a than the outer edge of the first low sound velocity region 18A. The outer edge 71 is farther from the center of the first excitation electrode 14a than the outer edge 81. Both the outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b are farther from the center of the first excitation electrode 14a than the outer edge of the second low sound velocity region 18B. The outer edge 72 is farther from the center of the first excitation electrode 14a than the outer edge 82.

[0222] <Fourth embodiment>

[0223] Next, refer to Fig.21 , the structure of the crystal resonator element 410 according to the fourth embodiment is described. Fig.21 It is a cross-sectional view of a crystal resonator element according to a fourth embodiment.

[0224] In a plan view, the outer edge 21A of the first portion 21 and the outer edge 22A of the second portion 22 of the mass adding film 20 overlap with the outer edge 81 of the second excitation electrode 14b. The outer edge 21A of the first portion 21 and the outer edge 22A of the second portion 22 of the mass adding film 20 are located between the outer edge 71 and the outer edge 72 of the first excitation electrode 14a. The length A is substantially equal to the length C and is smaller than the length B (A=C<B). The length E1 is substantially equal to the length D1 (E1=D1), the length E1 is substantially equal to the length D1 (E2=D2), and the length E1 is substantially equal to the length E2 (E1=E2).

[0225] In a plan view, the outer edge of the first low acoustic velocity region 18A overlaps not only the outer edge 21A of the first portion 21 of the mass adding film 20 but also the outer edge 81 of the second excitation electrode 14 b. The outer edge of the second low acoustic velocity region 18B overlaps not only the outer edge 22A of the second portion 22 of the mass adding film 20 but also the outer edge 82 of the second excitation electrode 14 b.

[0226] In a plan view, one of the outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b is farther from the center of the first excitation electrode 14a than the outer edge of the first low sound velocity region 18A. One of the outer edge 72 of the first excitation electrode 14a and the outer edge 82 of the second excitation electrode 14b is farther from the center of the first excitation electrode 14a than the outer edge of the second low sound velocity region 18B.

[0227] Next, refer to Fig. 22 as well as Fig.23 , the influence of positional deviation in the fourth embodiment is explained. Fig. 22 as well as Fig.23 It is a diagram for explaining the influence of positional deviation in the fourth embodiment. Fig. 22 4 is a cross-sectional view of the quartz-crystal resonator element 410 when the mass addition film 20 is offset by dz in the positive direction of the Z′ axis. Fig.23 4 is a cross-sectional view of the crystal resonator element 410 when the second excitation electrode 14 b is offset by dz in the negative direction of the Z′ axis.

[0228] In such Fig. 22 As shown in the figure, the mass-added film 20 is offset dz in the positive direction of the Z' axis and Fig.23As shown, when the second excitation electrode 14b is offset dz in the negative direction of the Z' axis, the second portion 22 of the mass addition film 20 extends from the second excitation electrode 14b to the positive direction of the Z' axis by an amount corresponding to the offset dz in a plan view. Therefore, the overlapping area of ​​the first excitation electrode 14a, the second excitation electrode 14b, and the second portion 22 of the mass addition film 20 is reduced by an amount corresponding to the offset dz. That is, the length E2d1 and the length E2d2 are expressed as E2d1=E2d2=E2-dz=D2-dz. The length E1d1 and the length E2d2 do not change from the length E1. That is, they are expressed as E1d1=E1d2=E1=D1. Therefore, in the present embodiment, when the mass addition film 20 is offset dz in the positive direction of the Z' axis, the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis change in a balanced manner, and the relationship of E2d1<E1d1 is established. In addition, when the second excitation electrode 14b is offset by dz in the positive direction of the Z' axis, the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis direction also changes, and the relationship E2d2<E1d2 holds. However, the outer edge 22A of the second portion 22 of the mass addition film 20 is located on the positive Z' direction side of the second low acoustic velocity region 18B, and the outer edge 72 of the first excitation electrode 14a is located on the positive Z' direction side. That is, as the second low acoustic velocity region 18B is used as a starting point to move toward the positive Z' direction side, the total thickness of the crystal vibration element 410 changes from Tp+Te1+Te2+Tf to Tp+Te1+Tf, to Tp+Te1, and to Tp. On the positive Z' direction side of the second low acoustic velocity region 18B, the total thickness of the crystal vibration element 410 decreases in stages, so the phase change is advanced. This alleviates the problem caused by the change in balance between the lengths of the first low-acoustic-speed region 18A and the second low-acoustic-speed region 18B along the Z′-axis direction.

[0229] <Fifth Embodiment>

[0230] Next, refer to Fig.24 , the structure of the crystal resonator element 510 according to the fifth embodiment is described. Fig.24 It is a cross-sectional view of the crystal resonator element according to the fifth embodiment.

[0231] In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 overlaps with the outer edge 71 of the first excitation electrode 14a, and the outer edge 22A of the second portion 22 of the mass addition film 20 overlaps with the outer edge 72 of the first excitation electrode 14a. The outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 22A of the second portion 22 are located between the outer edge 81 and the outer edge 82 of the second excitation electrode 14b. The length A is substantially equal to the length B and is smaller than the length C (A=B<C). The length E1 is substantially equal to the length D1 (E1=D1), the length E1 is substantially equal to the length D1 (E2=D2), and the length E1 is substantially equal to the length E2 (E1=E2).

[0232] In a plan view, the outer edge of the first low acoustic velocity region 18A overlaps not only the outer edge 21A of the first portion 21 of the mass adding film 20 but also the outer edge 71 of the first excitation electrode 14a. The outer edge of the second low acoustic velocity region 18B overlaps not only the outer edge 22A of the second portion 22 of the mass adding film 20 but also the outer edge 72 of the first excitation electrode 14a.

[0233] In a plan view, one of the outer edge 71 of the first excitation electrode 14a and the outer edge 81 of the second excitation electrode 14b is farther from the center of the first excitation electrode 14a than the outer edge of the first low sound velocity region 18A. One of the outer edge 72 of the first excitation electrode 14a and the outer edge 82 of the second excitation electrode 14b is farther from the center of the first excitation electrode 14a than the outer edge of the second low sound velocity region 18B.

[0234] Next, refer to Fig.25 as well as Fig.26 , the influence of positional deviation in the fifth embodiment is explained. Fig.25 as well as Fig.26 It is a diagram for explaining the influence of positional deviation in the fifth embodiment. Fig.25 4 is a cross-sectional view of the quartz-crystal resonator element 510 when the mass addition film 20 is offset by dz in the positive direction of the Z′ axis. Fig.26 4 is a cross-sectional view of the crystal resonator element 510 when the second excitation electrode 14 b is offset by dz in the negative direction of the Z′ axis.

[0235] like Fig.25As shown in FIG. 1 , when the mass addition film 20 is offset by dz in the positive direction of the Z' axis, the outer edge 22A of the second portion 22 of the mass addition film 20 is located between the outer edge 72 of the first excitation electrode 14a and the outer edge 82 of the second excitation electrode 14b in a plan view. The outer edge 71 of the first excitation electrode 14a is located between the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 81 of the second excitation electrode 14b. The second portion 22 of the mass addition film 20 extends from the first excitation electrode 14a to the positive direction of the Z' axis by the offset dz. Therefore, the area where the first excitation electrode 14a, the second excitation electrode 14b and the second portion 22 of the mass addition film 20 overlap is reduced by an amount corresponding to the offset dz. That is, the length E2d1 is expressed as E2d1=E2-dz=D2-dz. In addition, the area where the first excitation electrode 14a, the second excitation electrode 14b and the first portion 21 of the mass addition film 20 overlap does not change. That is, the length E1d1 is expressed as E1d1=E1=D1. Therefore, in the present embodiment, when the mass addition film 20 is offset by dz in the positive direction of the Z' axis, the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis are balanced and the relationship E2d1<E1d1 holds. In the present embodiment, when D1=D2, the difference in lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis when the mass addition film 20 is offset by dz in the positive direction of the Z' axis is dz. On the other hand, in the case of a structure in which the outer edge of the mass addition film, the outer edge of the first excitation electrode, and the outer edge of the second excitation electrode overlap as a comparative example, in the comparative example, the difference in lengths of the first low acoustic velocity region and the second low acoustic velocity region along the Z' axis when the mass addition film is offset by dz in the positive direction of the Z' axis is dz. Therefore, the deterioration of the electromechanical coupling coefficient k when the mass adding film 20 is positionally misaligned in the present embodiment is equivalent to the deterioration of the electromechanical coupling coefficient k when the mass adding film is positionally misaligned in the comparative example.

[0236] like Fig.26As shown, when the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis, the length E1d2 does not change from the length E1. That is, it is expressed as E1d2=E1=D1. In addition, the length E2d2 does not change from the length E2. That is, the length E2d2 is expressed as E2d2=E2=D2. Therefore, the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis direction does not change, and the relationship E1d2=E2d2 holds. On the other hand, in the comparative example, the difference in the lengths of the first low acoustic velocity region and the second low acoustic velocity region along the Z' axis direction when the second excitation electrode is offset by dz in the negative direction of the Z' axis is dz. Therefore, in this embodiment, the deterioration of the electromechanical coupling coefficient k when the second excitation electrode is offset is suppressed compared to the deterioration of the electromechanical coupling coefficient k when the second excitation electrode is offset in the comparative example. That is, even if the second excitation electrode 14 b is offset by dz in the negative direction of the Z′ axis, an increase in k_A0 is suppressed and a decrease in k_S0 is suppressed.

[0237] <Sixth embodiment>

[0238] Next, refer to Fig. 27 , the structure of the crystal resonator element 610 according to the sixth embodiment is described. Fig. 27 It is a cross-sectional view of the crystal resonator element according to the sixth embodiment.

[0239] The material of the mass addition film 20 is an insulator, such as silicon oxide or silicon nitride. In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 overlaps with the outer edge 81 of the second excitation electrode 14b, and the outer edge 22A of the second portion 22 of the mass addition film 20 overlaps with the outer edge 82 of the second excitation electrode 14b. The outer edges 71 and 72 of the first excitation electrode 14a are located between the outer edge 21A and the outer edge 22A of the first portion 21 of the mass addition film 20. The length A is substantially equal to the length C and is greater than the length B (B<A=C). The length E1 is smaller than the length D1 (D1<E1), the length E2 is smaller than the length D2 (D2<E2), and the length E1 is substantially equal to the length E2 (E1=E2).

[0240] In a plan view, the outer edge of the first low acoustic velocity region 18A overlaps with the outer edge 71 of the first excitation electrode 14 a . The outer edge of the second low acoustic velocity region 18B overlaps with the outer edge 72 of the first excitation electrode 14 a .

[0241] In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 81 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the first low acoustic velocity region 18A. The outer edge 21A and the outer edge 81 are equally spaced from the center of the first excitation electrode 14a. The outer edge 22A of the second portion 22 of the mass addition film 20 and the outer edge 82 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the second low acoustic velocity region 18B. The outer edge 22A and the outer edge 82 are equally spaced from the center of the first excitation electrode 14a.

[0242] When the dimension of the portion of the first portion 21 of the mass addition film 20 extending from the first excitation electrode 14a to the negative Z'-axis direction is D'1, the length E1 is expressed as E1=D1-D'1. When the dimension of the portion of the second portion 22 of the mass addition film 20 extending from the first excitation electrode 14a to the positive Z'-axis direction is D'2, the length E2 is expressed as E2=D2-D'2.

[0243] Next, refer to Fig.28 as well as Fig.29 , the influence of positional deviation in the sixth embodiment is explained. Fig.28 as well as Fig.29 It is a diagram for explaining the influence of positional deviation in the sixth embodiment. Fig.28 4 is a cross-sectional view of the crystal resonator element 610 when the mass addition film 20 is offset by dz in the positive direction of the Z′ axis. Fig.29 4 is a cross-sectional view of the crystal resonator element 610 when the second excitation electrode 14 b is offset by dz in the negative direction of the Z′ axis.

[0244] like Fig.28 As shown, when the mass addition film 20 is offset by dz in the positive direction of the Z' axis, the first low acoustic velocity region 18A is enlarged by an amount corresponding to the offset dz. That is, the length E1d1 is expressed as E1d1=E1+dz=(D1-D'1)+dz. In addition, the second low acoustic velocity region 18B is reduced by an amount corresponding to the offset dz. That is, the length E2d1 is expressed as E2d1=E2-dz=(D2-D'2)-dz. Therefore, the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis change in a balanced manner, and the relationship of E2d1<E1d1 holds. In the present embodiment, when D1=D2 and D'1=D'2, that is, E1=E2, the difference in the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis when the mass addition film 20 is offset by dz in the positive direction of the Z' axis is 2dz.

[0245] like Fig.29 As shown, when the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis, the length E1d2 does not change from the length E1. That is, it is expressed as E1d2=E1=D1-D'1. In addition, the length E2d2 does not change from the length E2. That is, it is expressed as E2d2=E2=D2-D'2. In this embodiment, when D1=D2 and D'1=D'2, that is, E1=E2, even if the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis, the balance of the lengths of the first low acoustic velocity region 18A and the second low acoustic velocity region 18B along the Z' axis direction does not change, and the relationship E1d2=E2d2 holds. Therefore, even if the second excitation electrode 14b is offset by dz in the negative direction of the Z' axis, the increase of k_A0 is suppressed and the decrease of k_S0 is suppressed.

[0246] <Seventh embodiment>

[0247] Next, refer to Fig.30 , the structure of the crystal resonator element 710 of the seventh embodiment is described. Fig.30 It is a cross-sectional view of a crystal resonator element according to the seventh embodiment.

[0248] The material of the mass addition film 20 is a conductor, for example, the same material as the first excitation electrode 14a. In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 overlaps with the outer edge 81 of the second excitation electrode 14b, and the outer edge 22A of the second portion 22 of the mass addition film 20 overlaps with the outer edge 82 of the second excitation electrode 14b. The outer edges 71 and 72 of the first excitation electrode 14a are located between the outer edge 21A and the outer edge 22A of the first portion 21 of the mass addition film 20. The length A is substantially equal to the length C and is greater than the length B (B<A=C). The length E1 is smaller than the length D1 (D1<E1), the length E2 is smaller than the length D2 (D2<E2), and the length E1 is substantially equal to the length E2 (E1=E2). The length E1 is expressed as E1=D1-D'1, and the length E2 is expressed as E2=D2-D'2.

[0249] In a plan view, the outer edge of the first low acoustic velocity region 18A overlaps with the outer edge 71 of the first excitation electrode 14 a . The outer edge of the second low acoustic velocity region 18B overlaps with the outer edge 72 of the first excitation electrode 14 a .

[0250] In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 81 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the first low acoustic velocity region 18A. The outer edge 21A and the outer edge 81 are equally spaced from the center of the first excitation electrode 14a. The outer edge 22A of the second portion 22 of the mass addition film 20 and the outer edge 82 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the second low acoustic velocity region 18B. The outer edge 22A and the outer edge 82 are equally spaced from the center of the first excitation electrode 14a.

[0251] The first portion 21 of the mass addition film 20 extends from the first excitation electrode 14a to the negative Z' direction side. The second portion 22 of the mass addition film 20 extends from the first excitation electrode 14a to the positive Z' direction side. The mass addition film 20 and the first excitation electrode 14a have the same potential, so the portion of the mass addition film 20 extending from the first excitation electrode 14a functions as an excitation electrode. Therefore, in a plan view, the region outside the first excitation electrode 14a where the first portion 21 of the mass addition film 20 overlaps with the second excitation electrode 14b is the first outer high acoustic velocity region 191A, and the region outside the first excitation electrode 14a where the second portion 22 of the mass addition film 20 overlaps with the second excitation electrode 14b is the second outer high acoustic velocity region 191B. The sum of the thicknesses in the high acoustic velocity region 17 is Tp+Te1+Te2, and the sum of the thicknesses of the first outer high acoustic velocity region 191A and the second outer high acoustic velocity region 191B is Tp+Tf+Te2. Therefore, when the material of the mass addition film 20 is the same as that of the first excitation electrode 14a and the relationship of Tf<Te1 holds, the sound speed in the first outer high acoustic velocity region 191A and the second outer high acoustic velocity region 191B is greater than the sound speed in the high acoustic velocity region 17. That is, the sound speed in the high acoustic velocity region 17 is smaller than that in the outer high acoustic velocity region 191, and the sound speed in the low acoustic velocity region 18 is smaller than that in the high acoustic velocity region 17. When the material of the mass addition film 20 is the same as that of the first excitation electrode 14a and the relationship of Tf=Te1 holds, the sound speed in the first outer high acoustic velocity region 191A and the second outer high acoustic velocity region 191B is substantially equal to the sound speed in the high acoustic velocity region 17. That is, the sound speed in the outer high acoustic velocity region 191 is substantially equal to the sound speed in the high acoustic velocity region 17 and is greater than the sound speed in the low acoustic velocity region 18. When the material of the mass added film 20 is the same as that of the first excitation electrode 14a and Te1<Tf, the sound speed in the first outer high sound speed region 191A and the second outer high sound speed region 191B is lower than the sound speed in the high sound speed region 17. That is, the sound speed in the outer high sound speed region 191 is lower than the sound speed in the high sound speed region 17, and the sound speed in the low sound speed region 18 is lower than the sound speed in the outer high sound speed region 191.

[0252] Furthermore, when the material of the mass addition film 20 is different from the material of the first excitation electrode 14a, the sound velocity of the outer high acoustic velocity region 191 is also smaller than the sound velocity of the high acoustic velocity region 17 when the relationship of Tf<Te1 holds. For example, when the mass per unit area of ​​the mass addition film 20 is larger than the mass per unit area of ​​the first excitation electrode 14a, the sound velocity of the outer high acoustic velocity region 191 is smaller than the sound velocity of the high acoustic velocity region 17. When the mass per unit area of ​​the mass addition film 20 is equal to the mass per unit area of ​​the first excitation electrode 14a, the sound velocity of the outer high acoustic velocity region 191 is equal to the sound velocity of the high acoustic velocity region 17. When the mass per unit area of ​​the mass addition film 20 is smaller than the mass per unit area of ​​the first excitation electrode 14a, the sound velocity of the outer high acoustic velocity region 191 is larger than the sound velocity of the high acoustic velocity region 17.

[0253] In the crystal resonator element 610 of the sixth embodiment and the crystal resonator element 710 of the seventh embodiment, the relationship B<A=C holds, but as long as the relationship B<C holds, the relationship C<A may also hold. That is, the relationship B<C<A may also hold.

[0254] <Eighth Embodiment>

[0255] Next, refer to Fig.31 , the structure of the crystal resonator element 810 of the eighth embodiment is described. Fig.31 It is a cross-sectional view of a crystal resonator element according to the eighth embodiment.

[0256] In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 22A of the second portion 22 are located between the outer edge 81 and the outer edge 82 of the second excitation electrode 14b. The outer edge 71 of the first excitation electrode 14a is located between the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 81 of the second excitation electrode 14b. The outer edge 72 of the first excitation electrode 14a is located between the outer edge 22A of the second portion 22 of the mass addition film 20 and the outer edge 82 of the second excitation electrode 14b. The length A is larger than the length B and smaller than the length C (B<A<C). The length E1 is smaller than the length D1 (D1<E1), the length E2 is smaller than the length D2 (D2<E2), and the length E1 and the length E2 are substantially equal (E1=E2). The length E1 is expressed as E1=D1-D'1, and the length E2 is expressed as E2=D2-D'2.

[0257] In a plan view, the outer edge of the first low acoustic velocity region 18A overlaps with the outer edge 71 of the first excitation electrode 14 a . The outer edge of the second low acoustic velocity region 18B overlaps with the outer edge 72 of the first excitation electrode 14 a .

[0258] In a plan view, the outer edge 21A of the first portion 21 of the mass addition film 20 and the outer edge 81 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the first low acoustic velocity region 18A. The outer edge 81 is farther from the center of the first excitation electrode 14a than the outer edge 21A. The outer edge 22A of the second portion 22 of the mass addition film 20 and the outer edge 82 of the second excitation electrode 14b are both farther from the center of the first excitation electrode 14a than the outer edge of the second low acoustic velocity region 18B. The outer edge 82 is separated from the center of the first excitation electrode 14a by the same degree as the outer edge 22A.

[0259] Reference Fig.32 as well as Fig.33 , changes in the electromechanical coupling coefficient k in the comparative example and the examples based on the first to eighth embodiments are described. Fig.32 : is a table showing simulation results of comparative examples and examples based on the first to eighth embodiments. Fig.33 This is a table showing simulation conditions of comparative examples and examples based on the first to eighth embodiments.

[0260] (Comparative Example)

[0261] A=B=C

[0262] Tp=1.00μm

[0263] Tf=0.02μm

[0264] Te1=Te2=0.05μm

[0265] Px=Pz=100μm

[0266] Xf=19μm

[0267] Zf=30μm

[0268] Wx=28μm

[0269] Wz=20μm

[0270] Wgx=Wgz=0μm

[0271] Xe1=75μm

[0272] Ze1=70μm

[0273] Xe2=75μm

[0274] Ze2=70μm

[0275] (Example based on the first embodiment)

[0276] A<B<C

[0277] Tp=1.00μm

[0278] Tf=0.02μm

[0279] Te1=Te2=0.05μm

[0280] Px=Pz=100μm

[0281] Xf=27μm

[0282] Zf=38μm

[0283] Wx=24μm

[0284] Wz=16μm

[0285] Wgx=Wgz=4μm

[0286] Xe1=75μm

[0287] Ze1=70μm

[0288] Xe2=79μm

[0289] Ze2=74μm

[0290] (Example based on the second embodiment)

[0291] A<B=C

[0292] Tp=1.00μm

[0293] Tf=0.02μm

[0294] Te1=Te2=0.05μm

[0295] Px=Pz=100μm

[0296] Xf=27μm

[0297] Zf=38μm

[0298] Wx=24μm

[0299] Wz=16μm

[0300] Wgx=Wgz=4μm

[0301] Xe1=75μm

[0302] Ze1=70μm

[0303] Xe2=75μm

[0304] Ze2=70μm

[0305] (Example based on the third embodiment)

[0306] A<C<B

[0307] Tp=1.00μm

[0308] Tf=0.02μm

[0309] Te1=Te2=0.05μm

[0310] Px=Pz=100μm

[0311] Xf=27μm

[0312] Zf=38μm

[0313] Wx=26μm

[0314] Wz=18μm

[0315] Wgx=Wgz=4μm

[0316] Xe1=79μm

[0317] Ze2=74μm

[0318] Xe2=75μm

[0319] Ze2=70μm

[0320] (Example based on the fourth embodiment)

[0321] A=C<B

[0322] Tp=1.00μm

[0323] Tf=0.02μm

[0324] Te1=Te2=0.05μm

[0325] Px=Pz=100μm

[0326] Xf=27μm

[0327] Zf=38μm

[0328] Wx=26μm

[0329] Wz=18μm

[0330] Wgx=Wgz=2μm

[0331] Xe1=79μm

[0332] Ze2=74μm

[0333] Xe2=75μm

[0334] Ze2=70μm

[0335] (Example based on the fifth embodiment)

[0336] A=B<C

[0337] Tp=1.00μm

[0338] Tf=0.02μm

[0339] Te1=Te2=0.05μm

[0340] Px=Pz=100μm

[0341] Xf=19μm

[0342] Zf=30μm

[0343] Wx=28μm

[0344] Wz=20μm

[0345] Wgx=Wgz=0μm

[0346] Xe1=75μm

[0347] Ze2=70μm

[0348] Xe2=79μm

[0349] Ze2=74μm

[0350] (Example based on the sixth embodiment)

[0351] B<A=C

[0352] Tp=1.00μm

[0353] Tf=0.02μm

[0354] Te1=Te2=0.05μm

[0355] Px=Pz=100μm

[0356] Xf=11μm

[0357] Zf=22μm

[0358] Wx=32μm

[0359] Wz=24μm

[0360] Wgx=Wgz=-4μm

[0361] Xe1=75μm

[0362] Ze2=70μm

[0363] Xe2=79μm

[0364] Ze2=74μm

[0365] (Example based on the seventh embodiment)

[0366] B<A=C

[0367] Tp=1.00μm

[0368] Tf=0.02μm

[0369] Te1=Te2=0.05μm

[0370] Px=Pz=100μm

[0371] Xf=11μm

[0372] Zf=22μm

[0373] Wx=32μm

[0374] Wz=24μm

[0375] Wgx=Wgz=-4μm

[0376] Xe1=75μm

[0377] Ze2=70μm

[0378] Xe2=79μm

[0379] Ze2=74μm

[0380] (Example based on the eighth embodiment)

[0381] B<A<C

[0382] Tp=1.00μm

[0383] Tf=0.02μm

[0384] Te1=Te2=0.05μm

[0385] Px=Pz=100μm

[0386] Xf=11μm

[0387] Zf=22μm

[0388] Wx=32μm

[0389] Wz=24μm

[0390] Wgx=Wgz=-4μm

[0391] Xe1=75μm

[0392] Ze2=70μm

[0393] Xe2=87μm

[0394] Ze2=82μm

[0395] Fig.32 The "frame offset" in the table means a state where the position of the mass addition film 20 is offset relative to the positions of the first excitation electrode 14a and the second excitation electrode 14b. The "back offset" means a state where the position of the second excitation electrode 14b is offset relative to the positions of the mass addition film 20 and the first excitation electrode 14a. The "both offsets" means a state where the position of the mass addition film 20 is offset relative to the position of the first excitation electrode 14a, and the position of the second excitation electrode 14b is offset relative to the position of the first excitation electrode 14a in a direction opposite to the offset of the mass addition film 20.

[0396] In the comparative example, the change amount Δk of k in the frame offset of the S0 mode is -0.15%, the change amount Δk of k in the back offset of the S0 mode is -0.04%, and the change amount Δk of k in the both-side offset of the S0 mode is -0.28%. In the comparative example, the change amount Δk of k in the frame offset of the A0Z mode is 1.07%, the change amount Δk of k in the back offset of the A0Z mode is 0.69%, and the change amount Δk of k in the both-side offset of the A0Z mode is 1.43%.

[0397] In the example based on the first embodiment, the change amount Δk of k in the frame offset of the S0 mode is 0.00%, the change amount Δk of k in the back offset of the S0 mode is 0.00%, and the change amount Δk of k in the both-side offset of the S0 mode is 0.00%. The Δk of the S0 mode in the example based on the first embodiment is smaller than the Δk of the S0 mode in the comparative example. That is, in the example based on the first embodiment, the decrease of k in the S0 mode caused by the position offset is suppressed.

[0398] In the example based on the first embodiment, the change amount Δk of k in the frame offset of the A0Z mode is 0.02%, the change amount Δk of k in the back offset of the A0Z mode is 0.05%, and the change amount Δk of k in the both-side offset of the A0Z mode is 0.02%. The Δk of the A0Z mode in the example based on the first embodiment is smaller than the Δk of the A0Z mode in the comparative example. That is, in the example based on the first embodiment, the increase of k in the A0Z mode caused by the position offset is suppressed.

[0399] In the example based on the second embodiment, the change amount Δk of k in the frame offset of the S0 mode is 0.00%, the change amount Δk of k in the back offset of the S0 mode is 0.01%, and the change amount Δk of k in the both offsets of the S0 mode is 0.01%. The change amount Δk of k in the frame offset of the A0Z mode is 0.03%, the change amount Δk of k in the back offset of the A0Z mode is 0.06%, and the change amount Δk of k in the both offsets of the A0Z mode is 0.05%.

[0400] In the example based on the third embodiment, the change amount Δk of k in the frame offset of the S0 mode is -0.01%, the change amount Δk of k in the back offset of the S0 mode is -0.02%, and the change amount Δk of k in the both offsets of the S0 mode is -0.06%. The change amount Δk of k in the frame offset of the A0Z mode is 0.17%, the change amount Δk of k in the back offset of the A0Z mode is 0.19%, and the change amount Δk of k in the both offsets of the A0Z mode is 0.35%.

[0401] In the example based on the fourth embodiment, the change amount Δk of k in the frame offset of the S0 mode is -0.01%, the change amount Δk of k in the back offset of the S0 mode is -0.02%, and the change amount Δk of k in the both offsets of the S0 mode is -0.06%. The change amount Δk of k in the frame offset of the A0Z mode is 0.34%, the change amount Δk of k in the back offset of the A0Z mode is 0.36%, and the change amount Δk of k in the both offsets of the A0Z mode is 0.51%.

[0402] In the examples based on the second to fourth embodiments, the decrease of k in the S0 mode due to positional shift is suppressed, as in the example based on the first embodiment. In the example based on the second embodiment, the increase of k in the A0Z mode due to positional shift is suppressed, as in the example based on the first embodiment.

[0403] In the example based on the fifth embodiment, the change amount Δk of k in the frame offset of the S0 mode is -0.13%, the change amount Δk of k in the back offset of the S0 mode is 0.00%, and the change amount Δk of k in the both offsets of the S0 mode is -0.14%. The change amount Δk of k in the frame offset of the A0Z mode is 0.89%, the change amount Δk of k in the back offset of the A0Z mode is 0.02%, and the change amount Δk of k in the both offsets of the A0Z mode is 0.96%.

[0404] In the example based on the sixth embodiment, the change amount Δk of k in the frame offset of the S0 mode is -0.13%, the change amount Δk of k in the back offset of the S0 mode is 0.00%, and the change amount Δk of k in the both offsets of the S0 mode is -0.15%. The change amount Δk of k in the frame offset of the A0Z mode is 1.01%, the change amount Δk of k in the back offset of the A0Z mode is 0.03%, and the change amount Δk of k in the both offsets of the A0Z mode is 1.06%.

[0405] In the examples based on the fifth and sixth embodiments, the Δk of the S0 mode and the Δk of the A0Z mode in the frame offset are substantially equal to the Δk of the S0 mode and the Δk of the A0Z mode in the comparative example. In the examples based on the fifth and sixth embodiments, the decrease of the Δk of the S0 mode in the back offset and the both offset is suppressed, and the increase of the Δk of the A0Z mode in the back offset and the both offset is suppressed.

[0406] In the example based on the seventh embodiment, the change amount Δk of k in the frame offset of the S0 mode is -0.20%, the change amount Δk of k in the back offset of the S0 mode is 0.00%, and the change amount Δk of k in the both offsets of the S0 mode is -0.22%. The change amount Δk of k in the frame offset of the A0Z mode is 1.27%, the change amount Δk of k in the back offset of the A0Z mode is 0.11%, and the change amount Δk of k in the both offsets of the A0Z mode is 1.31%.

[0407] In the example based on the eighth embodiment, the change amount Δk of k in the frame offset of the S0 mode is -0.18%, the change amount Δk of k in the back offset of the S0 mode is 0.00%, and the change amount Δk of k in the both offsets of the S0 mode is -0.19%. The change amount Δk of k in the frame offset of the A0Z mode is 1.29%, the change amount Δk of k in the back offset of the A0Z mode is 0.07%, and the change amount Δk of k in the both offsets of the A0Z mode is 1.31%.

[0408] In the examples based on the seventh and eighth embodiments, the Δk of the S0 mode and the Δk of the A0Z mode in the frame offset are worse than the Δk of the S0 mode and the Δk of the A0Z mode in the comparative example. However, in the examples based on the seventh and eighth embodiments, the decrease of the Δk of the S0 mode in the back offset and the both offset is suppressed, and the increase of the Δk of the A0Z mode in the back offset and the both offset is suppressed.

[0409] Next, refer to Fig.34 , the structure of the crystal resonator element 910 of the ninth embodiment is described. Fig.34 It is a cross-sectional view of a crystal resonator element according to the ninth embodiment.

[0410] In the present embodiment, the mass adding film 20 is provided with a metal of a material different from that of the first excitation electrode 14a. From the viewpoint of efficiently adding mass and reducing the sound velocity in the low sound velocity region 18, it is preferable that the specific gravity of the mass adding film 20 is greater than that of the first excitation electrode 14a. Thus, the film forming process of the mass adding film 20 can be shortened, and manufacturing efficiency can be improved.

[0411] Next, refer to Fig.35 , the structure of the crystal resonator element 1010 according to the tenth embodiment is described. Fig.35 It is a top view of the crystal resonator element according to the tenth embodiment.

[0412] The third portion 23 and the fourth portion 24 of the mass adding film 20 are omitted. The first portion 21 and the second portion 22 of the mass adding film 20 are provided in a strip shape that is separated from each other and extends in the X-axis direction.

[0413] Next, refer to Fig.36 , the structure of the crystal resonator element 1110 according to the eleventh embodiment is described. Fig.36 It is a top view of the crystal resonator element according to the eleventh embodiment.

[0414] The first portion 21 and the second portion 22 of the mass adding film 20 are omitted. The third portion 23 and the fourth portion 24 of the mass adding film 20 are provided in a strip shape that is separated from each other and extends in the Z′ axis direction.

[0415] The following supplementary notes describe part or all of the embodiments of the present invention. The present invention is not limited to the following supplementary notes.

[0416] <1>

[0417] A piezoelectric vibration element comprises: a piezoelectric sheet having a first main surface extending in a first direction and a second direction intersecting the first direction, and a second main surface opposite to the first main surface; a first excitation electrode arranged on the first main surface of the piezoelectric sheet; a second excitation electrode arranged on the second main surface of the piezoelectric sheet; and a mass addition film, at least a portion of which overlaps with the first excitation electrode, the mass addition film including a first portion and a second portion arranged to avoid a central portion of the first excitation electrode, the first excitation electrode having, when viewed from above, a first outer edge portion located on one side of the first direction relative to the central portion; and a second outer edge portion located on the other side of the first direction relative to the central portion, the second excitation electrode having, when viewed from above, a first outer edge portion located on the first direction relative to the central portion a third outer edge portion on one side; and a fourth outer edge portion on the other side in the first direction relative to the central portion, the first portion is arranged along the first outer edge portion, and the second portion is arranged along the second outer edge portion, when the area where the piezoelectric sheet, the first excitation electrode and the second excitation electrode overlap is set as a high acoustic velocity area, the area where the first part of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as a first low acoustic velocity area, and the area where the second part of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as a second low acoustic velocity area, when viewed from above, the third outer edge portion is farther away from the central portion than the first low acoustic velocity area, and when viewed from above, the fourth outer edge portion is farther away from the central portion than the second low acoustic velocity area.

[0418] <2>

[0419] A piezoelectric vibration element comprises: a piezoelectric sheet having a first main surface extending in a first direction and a second direction intersecting the first direction, and a second main surface opposite to the first main surface; a first excitation electrode arranged on the first main surface of the piezoelectric sheet; a second excitation electrode arranged on the second main surface of the piezoelectric sheet; and a mass addition film, at least a portion of which overlaps with the first excitation electrode, the mass addition film including a first portion and a second portion arranged avoiding a central portion of the first excitation electrode, the first excitation electrode having, when viewed from above, a first outer edge portion located on one side in the first direction relative to the central portion; and a second outer edge portion located on the other side in the first direction relative to the central portion, the second excitation electrode having, when viewed from above, a third outer edge portion located on one side in the first direction relative to the central portion; and a fourth outer edge portion located on the other side in the first direction relative to the central portion, the first portion being arranged along the first outer edge portion, the second portion being arranged along the second outer edge portion, and the piezoelectric sheet, the first excitation electrode, and the second excitation electrode being arranged The region where the electrodes overlap is set as a high acoustic velocity region, the region where the first portion of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a first low acoustic velocity region, and the region where the second portion of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a second low acoustic velocity region. When the dimension along the first direction between the end portion of the first portion on the side opposite to the second portion and the end portion of the second portion on the side opposite to the first portion in the mass addition film is set as A, the dimension along the first direction of the first excitation electrode is set as B, and the dimension along the first direction of the second excitation electrode is set as C, the relationship A=C<B holds. When viewed from above, the outer edge portion of the first low acoustic velocity region on the side opposite to the second low acoustic velocity region and the outer edge of the second low acoustic velocity region on the side opposite to the first low acoustic velocity region overlap with the first excitation electrode, and when viewed from above, the third outer edge portion and the fourth outer edge portion of the second excitation electrode overlap with the first excitation electrode.

[0420] <3>

[0421] According to the piezoelectric vibration element described in <1>, the first outer edge portion and the second outer edge portion overlap with the second excitation electrode in a plan view.

[0422] <4>

[0423] According to the piezoelectric vibration element described in any one of <1> to <3>, when the dimension along the first direction between the outer edge portion on the side opposite to the central portion of the first low sound velocity region and the outer edge portion on the side opposite to the central portion of the second low sound velocity region is set to E, and the distance along the first direction between the outer edge portion on the first low sound velocity region side in the high sound velocity region and the outer edge portion on the second low sound velocity region side is set to E', the dimension along the first direction of the first low sound velocity region and the dimension along the first direction of the second low sound velocity region are (1±0.04)×(E-E') / 2.

[0424] <5>

[0425] According to the piezoelectric vibration element described in <1>, when the dimension along the first direction between the end of the first part on the opposite side to the second part in the mass addition film and the end of the second part on the opposite side to the first part is set to A, and the dimension along the first direction of the first excitation electrode is set to B, the relationship A<B holds.

[0426] <6>

[0427] According to the piezoelectric vibration element described in <5>, when the dimension of the second excitation electrode along the first direction is represented by C, the relationship of A<B<C holds.

[0428] <7>

[0429] According to the piezoelectric vibration element described in <5>, when the dimension of the second excitation electrode along the first direction is represented by C, the relationship of A<B=C holds.

[0430] <8>

[0431] According to the piezoelectric vibration element described in <5>, when the dimension of the second excitation electrode along the first direction is represented by C, the relationship of A=C<B holds.

[0432] <9>

[0433] According to the piezoelectric vibration element described in <5>, when the dimension of the second excitation electrode along the first direction is represented by C, the relationship of A<C<B holds.

[0434] <10>

[0435] According to the piezoelectric vibration element described in <1>, when the dimension along the first direction between the end of the first part on the opposite side to the second part in the mass addition film and the end of the second part on the opposite side to the first part is set to A, the dimension along the first direction of the first excitation electrode is set to B, and the dimension along the first direction of the second excitation electrode is set to C, the relationship A=B<C holds.

[0436] <11>

[0437] According to the piezoelectric vibration element described in <1>, when the dimension along the first direction between the end of the first part on the opposite side to the second part in the mass addition film and the end of the second part on the opposite side to the first part is set to A, the dimension along the first direction of the first excitation electrode is set to B, and the dimension along the first direction of the second excitation electrode is set to C, the relationship B<A=C holds.

[0438] <12>

[0439] According to the piezoelectric vibration element described in <1>, when the dimension along the first direction between the end of the first part on the opposite side to the second part in the mass addition film and the end of the second part on the opposite side to the first part is set to A, the dimension along the first direction of the first excitation electrode is set to B, and the dimension along the first direction of the second excitation electrode is set to C, the relationship B<A<C holds.

[0440] <13>

[0441] The piezoelectric vibration element according to any one of <1> to <12>, wherein the material of the mass adding film is a conductor.

[0442] <14>

[0443] In the piezoelectric vibration element according to any one of <1> to <12>, the material of the mass added film is an insulator.

[0444] <15>

[0445] According to the piezoelectric vibration element described in any one of <1> to <14>, when the distance along the first direction between the end of the first part on the side opposite to the second part side in the mass addition film and the end of the second part on the side opposite to the first part side is set to A', and the dimension of the first excitation electrode along the first direction is set to B, the relationship A' / B≤0.5 holds.

[0446] <16>

[0447] According to the piezoelectric vibration element described in <15>, the relationship of 0.05≤A′ / B holds.

[0448] <17>

[0449] According to the piezoelectric vibration element described in <1>, the distance along the first direction between the outer edge portion of the first part of the mass addition film located on one side and the first outer edge portion of the first excitation electrode, and the distance along the first direction between the outer edge portion of the second part of the mass addition film located on the other side and the second outer edge portion of the first excitation electrode are greater than 0.5 μm.

[0450] <18>

[0451] According to the piezoelectric vibration element described in <17>, the distance along the first direction between the outer edge portion of the first part of the mass addition film located on one side and the first outer edge portion of the first excitation electrode, and the distance along the first direction between the outer edge portion of the second part of the mass addition film located on the other side and the second outer edge portion of the first excitation electrode are less than 8 μm.

[0452] <19>

[0453] According to the piezoelectric vibration element described in <1>, when the dimension of the first excitation electrode along the first direction is B and the dimension of the second excitation electrode along the first direction is C, the relationship of 3 μm ≤ CB holds.

[0454] <20>

[0455] According to the piezoelectric vibration element described in <19>, when the dimension of the first excitation electrode along the first direction is B and the dimension of the second excitation electrode along the first direction is C, the relationship of CB≤8 μm holds.

[0456] <21>

[0457] According to the piezoelectric vibration element described in any one of <1> to <20>, the mass-added film includes a third portion and a fourth portion provided avoiding a central portion of the first excitation electrode, the first excitation electrode having, in a plan view, a fifth outer edge portion located on one side in the second direction relative to the central portion; and a sixth outer edge portion located on the other side in the second direction relative to the central portion, the second excitation electrode having, in a plan view, a seventh outer edge portion located on one side in the second direction relative to the central portion; and an eighth outer edge portion located on the other side in the second direction relative to the central portion, the third portion being provided along the fifth outer edge portion, and the fourth portion being provided along the sixth outer edge portion, and when a region where the third portion of the mass-added film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is defined as a third low acoustic velocity region, and a region where the fourth portion of the mass-added film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is defined as a fourth low acoustic velocity region, the seventh outer edge portion is further away from the central portion than the third low acoustic velocity region in a plan view, and the eighth outer edge portion is further away from the central portion than the fourth low acoustic velocity region in a plan view.

[0458] <22>

[0459] According to the piezoelectric vibration element described in any one of <1> to <21>, the mass-added film includes a third portion and a fourth portion which are arranged to avoid the central portion of the first excitation electrode, and the first excitation electrode has, when viewed from above: a fifth outer edge portion located on one side in the second direction relative to the central portion; and a sixth outer edge portion located on the other side in the second direction relative to the central portion, and the second excitation electrode has, when viewed from above: a seventh outer edge portion located on one side in the second direction relative to the central portion; and an eighth outer edge portion located on the other side in the second direction relative to the central portion, the third portion is arranged along the fifth outer edge portion, and the fourth portion is arranged along the sixth outer edge portion, and an area where the third portion of the mass-added film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as The third low acoustic velocity region, a region where the fourth portion of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode and the second excitation electrode is set as the fourth low acoustic velocity region, the dimension along the second direction between the end of the third portion on the side opposite to the fourth portion in the mass addition film and the end of the fourth portion on the side opposite to the third portion is equal to the dimension of the second excitation electrode along the second direction and is smaller than the dimension of the first excitation electrode along the second direction, when viewed from above, the outer edge portion of the third low acoustic velocity region on the side opposite to the fourth low acoustic velocity region and the outer edge portion of the fourth low acoustic velocity region on the side opposite to the third low acoustic velocity region overlap with the first excitation electrode, and when viewed from above, the seventh outer edge portion and the eighth outer edge portion of the second excitation electrode overlap with the first excitation electrode.

[0460] <23>

[0461] According to the piezoelectric vibration element described in any one of <1> to <22>, the first excitation electrode has, when viewed from above: a fifth outer edge portion located on one side in the second direction relative to the central portion; and a sixth outer edge portion located on the other side in the second direction relative to the central portion, and when viewed from above, the fifth outer edge portion and the sixth outer edge portion overlap with the second excitation electrode.

[0462] <24>

[0463] The piezoelectric vibration element according to any one of <1> to <23>, wherein the piezoelectric sheet is a quartz-crystal sheet.

[0464] <25>

[0465] According to the piezoelectric vibration element described in <24>, the cut angle of the crystal piece is AT cut, BT cut or ST cut.

[0466] <26>

[0467] The piezoelectric vibration element according to any one of <1> to <25>, wherein a main vibration mode is thickness shear vibration.

[0468] In addition, the embodiment of the present invention is not limited to crystal oscillators, and can also be applied to other piezoelectric oscillators (Piezoelectric Resonator Unit). As piezoelectric sheets suitable for the piezoelectric oscillator of this embodiment, for example, piezoelectric ceramics such as lead zirconate titanate (PZT) and aluminum nitride, and piezoelectric single crystals such as lithium niobate and lithium tantalate can be listed, but it is not limited to these and can be appropriately selected.

[0469] The embodiments of the present invention are not particularly limited and can be appropriately applied to any device that performs electromechanical energy conversion by piezoelectric effect, such as a timing device, a sound generator, an oscillator, and a load sensor.

[0470] As described above, according to one embodiment of the present invention, it is possible to provide a piezoelectric vibration element capable of suppressing deterioration of the electromechanical coupling coefficient.

[0471] In addition, the above-described embodiments are used to make the understanding of the present invention easy, and are not used to limit the interpretation of the present invention. The present invention can be changed / improved without departing from its main purpose, and its equivalent is also included in the present invention. That is, the technical solution obtained by appropriately applying design changes to the embodiments and / or variations by those skilled in the art is included in the scope of the present invention as long as it has the characteristics of the present invention. For example, the various elements and their configurations, materials, conditions, shapes, sizes, etc. possessed by the embodiments and / or variations are not limited to the contents of the examples, and can be appropriately changed. In addition, the embodiments and variations are examples, and of course, the partial replacement or combination of the structures shown in different embodiments and / or variations can be performed, as long as they include the characteristics of the present invention, they are included in the scope of the present invention.

[0472] Description of Reference Numerals

[0473] 100...crystal oscillator; 1...crystal oscillator; 10...crystal vibration element; 11...crystal plate; 11A...upper surface; 11B...lower surface; 14a...first excitation electrode; 14b...second excitation electrode; 17...high sound velocity region; 18...low sound velocity region; 18A...first low sound velocity region; 18B...second low sound velocity region; 18C...third low sound velocity region; 18D...fourth low sound velocity region; 19...outer high sound velocity region; 19A...first outer high sound velocity region; 19B. ..the second outer high sound velocity region; 19C...the third outer high sound velocity region; 19D...the fourth outer high sound velocity region; 20...the mass addition membrane; 21...the first part; 21A...the outer edge; 21B...the inner edge; 22...the second part; 22A...the outer edge; 22B...the inner edge; 23...the third part; 23A...the outer edge; 23B...the inner edge; 24...the fourth part; 24A...the outer edge; 24B...the inner edge; 71, 72...the outer edge; 81, 82...the outer edge.

Claims

1. A piezoelectric vibration element, wherein: have: A piezoelectric sheet having a first main surface extending in a first direction and a second direction intersecting the first direction, and a second main surface opposite to the first main surface; A first excitation electrode is arranged on the first main surface of the piezoelectric sheet; A second excitation electrode is arranged on the second main surface of the piezoelectric sheet; as well as a mass additional film, at least a portion of which overlaps with the first excitation electrode, The mass added film includes a first portion and a second portion which are arranged away from a central portion of the first excitation electrode. The first excitation electrode has, in a plan view, a first outer edge portion located on one side of the central portion in the first direction, and a second outer edge portion located on the other side of the central portion in the first direction. The second excitation electrode has, in a plan view, a third outer edge portion located on one side of the central portion in the first direction, and a fourth outer edge portion located on the other side of the central portion in the first direction. The first portion is arranged along the first outer edge portion, The second portion is arranged along the second outer edge portion, When the region where the piezoelectric sheet, the first excitation electrode, and the second excitation electrode overlap is set as a high acoustic velocity region, the region where the first portion of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a first low acoustic velocity region, and the region where the second portion of the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a second low acoustic velocity region, In a plan view, the third outer edge portion is farther from the central portion than the first low sound velocity region. In a plan view, the fourth outer edge portion is farther away from the central portion than the second low sound velocity region.

2. A piezoelectric vibration element, wherein: have: A piezoelectric sheet having a first main surface extending in a first direction and a second direction intersecting the first direction, and a second main surface opposite to the first main surface; A first excitation electrode is arranged on the first main surface of the piezoelectric sheet; A second excitation electrode is arranged on the second main surface of the piezoelectric sheet; as well as a mass additional film, at least a portion of which overlaps with the first excitation electrode, The mass added film includes a first portion and a second portion which are arranged away from a central portion of the first excitation electrode. The first excitation electrode has, in a plan view, a first outer edge portion located on one side of the central portion in the first direction, and a second outer edge portion located on the other side of the central portion in the first direction. The second excitation electrode has, in a plan view, a third outer edge portion located on one side of the central portion in the first direction, and a fourth outer edge portion located on the other side of the central portion in the first direction. The first portion is arranged along the first outer edge portion, The second portion is arranged along the second outer edge portion, The region where the piezoelectric sheet, the first excitation electrode, and the second excitation electrode overlap is set as a high acoustic velocity region, the region where the first portion of the mass addition film further overlaps the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a first low acoustic velocity region, and the region where the second portion of the mass addition film further overlaps the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a second low acoustic velocity region, When the dimension along the first direction between the end of the first portion on the side opposite to the second portion and the end of the second portion on the side opposite to the first portion in the mass addition film is set to A, the dimension along the first direction of the first excitation electrode is set to B, and the dimension along the first direction of the second excitation electrode is set to C, The relationship A=C<B holds true. In a plan view, an outer edge of the first low acoustic velocity region on the side opposite to the second low acoustic velocity region and an outer edge of the second low acoustic velocity region on the side opposite to the first low acoustic velocity region overlap with the first excitation electrode. The third outer edge portion and the fourth outer edge portion of the second excitation electrode overlap with the first excitation electrode in a plan view.

3. The piezoelectric vibration element according to claim 1, wherein The first outer edge portion and the second outer edge portion overlap with the second excitation electrode in a plan view.

4. The piezoelectric vibration element according to any one of claims 1 to 3, wherein: When the dimension along the first direction between the outer edge of the first low sound velocity region on the side opposite to the central portion and the outer edge of the second low sound velocity region on the side opposite to the central portion is set as E, and the distance along the first direction between the outer edge of the first low sound velocity region side and the outer edge of the second low sound velocity region side in the high sound velocity region is set as E', A size of the first low sound velocity region along the first direction and a size of the second low sound velocity region along the first direction are (1±0.04)×(E−E′) / 2.

5. The piezoelectric vibration element according to claim 1, wherein When a dimension along the first direction between an end of the first portion of the mass addition film on the side opposite to the second portion and an end of the second portion on the side opposite to the first portion is defined as A, and a dimension of the first excitation electrode along the first direction is defined as B, The relationship A<B holds.

6. The piezoelectric vibration element according to claim 5, wherein: When the dimension of the second excitation electrode along the first direction is set to C, The relationship A<B<C holds true.

7. The piezoelectric vibration element according to claim 5, wherein: When the dimension of the second excitation electrode along the first direction is set to C, The relationship A<B=C holds.

8. The piezoelectric vibration element according to claim 5, wherein: When the dimension of the second excitation electrode along the first direction is set to C, The relationship A=C<B holds.

9. The piezoelectric vibration element according to claim 5, wherein: When the dimension of the second excitation electrode along the first direction is set to C, The relationship A<C<B holds true.

10. The piezoelectric vibration element according to claim 1, wherein When a dimension along the first direction between an end of the first portion on the side opposite to the second portion and an end of the second portion on the side opposite to the first portion in the mass addition film is set to A, a dimension along the first direction of the first excitation electrode is set to B, and a dimension along the first direction of the second excitation electrode is set to C, The relationship A=B<C holds.

11. The piezoelectric vibration element according to claim 1, wherein When a dimension along the first direction between an end of the first portion on the side opposite to the second portion and an end of the second portion on the side opposite to the first portion in the mass addition film is set to A, a dimension along the first direction of the first excitation electrode is set to B, and a dimension along the first direction of the second excitation electrode is set to C, The relationship B<A=C holds.

12. The piezoelectric vibration element according to claim 1, wherein When a dimension along the first direction between an end of the first portion on the side opposite to the second portion and an end of the second portion on the side opposite to the first portion in the mass addition film is set to A, a dimension along the first direction of the first excitation electrode is set to B, and a dimension along the first direction of the second excitation electrode is set to C, The relationship B<A<C holds.

13. The piezoelectric vibration element according to any one of claims 1 to 12, wherein: The material of the mass-added film is a conductor.

14. The piezoelectric vibration element according to any one of claims 1 to 12, wherein: The material of the mass additional film is an insulator.

15. The piezoelectric vibration element according to any one of claims 1 to 14, wherein: When a distance along the first direction between an end of the first portion of the mass addition film on the side opposite to the second portion and an end of the second portion on the side opposite to the first portion is defined as A', and a dimension of the first excitation electrode along the first direction is defined as B, The relationship A' / B≤0.5 holds.

16. The piezoelectric vibration element according to claim 15, wherein: The relationship of 0.05≤A' / B holds.

17. The piezoelectric vibration element according to claim 1, wherein A distance along the first direction between an outer edge portion of the first portion of the mass adding film located on the one side and the first outer edge portion of the first excitation electrode, and a distance along the first direction between an outer edge portion of the second portion of the mass adding film located on the other side and the second outer edge portion of the first excitation electrode are greater than or equal to 0.5 μm.

18. The piezoelectric vibration element according to claim 17, wherein: A distance along the first direction between an outer edge portion of the first portion of the mass adding film located on the one side and the first outer edge portion of the first excitation electrode, and a distance along the first direction between an outer edge portion of the second portion of the mass adding film located on the other side and the second outer edge portion of the first excitation electrode are 8 μm or less.

19. The piezoelectric vibration element according to claim 1, wherein When the dimension of the first excitation electrode along the first direction is set to B and the dimension of the second excitation electrode along the first direction is set to C, The relationship of 3μm≤CB holds true.

20. The piezoelectric vibration element according to claim 19, wherein When the dimension of the first excitation electrode along the first direction is set to B and the dimension of the second excitation electrode along the first direction is set to C, The relationship of CB≤8μm holds true.

21. The piezoelectric vibration element according to any one of claims 1 to 20, wherein: The mass added film includes a third portion and a fourth portion which are provided away from the central portion of the first excitation electrode. The first excitation electrode has, in a plan view, a fifth outer edge portion located on one side of the central portion in the second direction, and a sixth outer edge portion located on the other side of the central portion in the second direction. The second excitation electrode has, in a plan view, a seventh outer edge portion located on one side of the central portion in the second direction, and an eighth outer edge portion located on the other side of the central portion in the second direction. The third portion is arranged along the fifth outer edge portion, The fourth portion is arranged along the sixth outer edge portion, When the third portion of the area where the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as the third low sound velocity area, and the fourth portion of the area where the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as the fourth low sound velocity area, In a plan view, the seventh outer edge portion is farther from the central portion than the third low sound velocity region. In a plan view, the eighth outer edge portion is farther away from the central portion than the fourth low sound velocity region.

22. The piezoelectric vibration element according to any one of claims 1 to 21, wherein: The mass added film includes a third portion and a fourth portion which are provided away from the central portion of the first excitation electrode. The first excitation electrode has, in a plan view, a fifth outer edge portion located on one side of the central portion in the second direction, and a sixth outer edge portion located on the other side of the central portion in the second direction. The second excitation electrode has, in a plan view, a seventh outer edge portion located on one side of the central portion in the second direction, and an eighth outer edge portion located on the other side of the central portion in the second direction. The third portion is arranged along the fifth outer edge portion, The fourth portion is arranged along the sixth outer edge portion, The third portion of the area where the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a third low sound velocity area, and the fourth portion of the area where the mass addition film is further overlapped on the piezoelectric sheet, the first excitation electrode, and the second excitation electrode is set as a fourth low sound velocity area, A dimension along the second direction between an end of the third portion of the mass addition film on the side opposite to the fourth portion and an end of the fourth portion on the side opposite to the third portion is equal to a dimension of the second excitation electrode along the second direction and is smaller than a dimension of the first excitation electrode along the second direction. In a plan view, an outer edge of the third low sound velocity region on the side opposite to the fourth low sound velocity region and an outer edge of the fourth low sound velocity region on the side opposite to the third low sound velocity region overlap with the first excitation electrode. The seventh outer edge portion and the eighth outer edge portion of the second excitation electrode overlap with the first excitation electrode in a plan view.

23. The piezoelectric vibration element according to any one of claims 1 to 22, wherein: The first excitation electrode has, in a plan view, a fifth outer edge portion located on one side of the central portion in the second direction, and a sixth outer edge portion located on the other side of the central portion in the second direction. The fifth outer edge portion and the sixth outer edge portion overlap with the second excitation electrode in a plan view.

24. The piezoelectric vibration element according to any one of claims 1 to 23, wherein: The piezoelectric plate is a crystal plate.

25. The piezoelectric vibration element according to claim 24, wherein: The cutting angle of the crystal sheet is AT cutting, BT cutting or ST cutting.

26. The piezoelectric vibration element according to any one of claims 1 to 25, wherein: The main vibration mode is thickness shear vibration.

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