Piezoelectric vibration element and method for manufacturing same

Abstract

This piezoelectric vibration element comprises a piezoelectric substrate having a first main surface and a second main surface that oppose each other, a first excitation electrode that is provided on the first main surface of the piezoelectric substrate, and a second excitation electrode that is provided on the second main surface of the piezoelectric substrate, wherein: a plurality of first recesses and protrusions are provided in a region of the first main surface of the piezoelectric substrate that overlaps the first excitation electrode, and a plurality of second recesses and protrusions are provided in a region of the second main surface of the piezoelectric substrate that overlaps the second excitation electrode; and a first maximum dimension of the plurality of first recesses and protrusions in the thickness direction of the piezoelectric substrate is different from a second maximum dimension of the plurality of second recesses and protrusions in the thickness direction.

Description

Piezoelectric vibration element and method for manufacturing the same

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

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

[0003] For example, Patent Document 1 discloses a piezoelectric device including a piezoelectric vibration piece including a vibration portion, a frame portion surrounding the vibration portion, and a connecting portion connecting the vibration portion and the frame portion, and a lid and a base joined to the front and back surfaces of the frame portion of the piezoelectric vibration piece.

[0004] Japanese Unexamined Patent Application Publication No. 2015 - 33035

[0005] By the way, when manufacturing a piezoelectric vibration element, the frequency of the piezoelectric vibration element may be adjusted by cutting the excitation electrode by laser processing or ion beam processing. In such a case, an improvement in productivity due to an improvement in the processing efficiency and processing accuracy of the excitation electrode is required.

[0006] The present invention has been made in view of such circumstances, and aims to provide a piezoelectric vibration element and a method for manufacturing the same that can improve productivity.

[0007] The piezoelectric vibration element according to one aspect of the present invention includes a piezoelectric substrate having a first main surface and a second main surface facing each other, a first excitation electrode provided on the first main surface of the piezoelectric substrate, and a second excitation electrode provided on the second main surface of the piezoelectric substrate. In a region of the first main surface of the piezoelectric substrate that overlaps with the first excitation electrode, a plurality of first irregularities are provided. In a region of the second main surface of the piezoelectric substrate that overlaps with the second excitation electrode, a plurality of second irregularities are provided. A first maximum dimension in the thickness direction of the plurality of first irregularities is different from a second maximum dimension in the thickness direction of the plurality of second irregularities.

[0008] A method for manufacturing a piezoelectric vibration element according to one aspect of the present invention involves preparing a quartz crystal having X, Y, and Z axes as crystal axes; identifying the X' and Y' axes by rotating the X and Y axes by a rotation angle φ with the Z axis as the axis of rotation; cutting the quartz crystal with a plane perpendicular to the X' axis; identifying the Y'' and Z' axes by rotating the Y' and Z axes by a rotation angle θ with the X' axis as the axis of rotation; cutting the quartz crystal with a cutting plane perpendicular to the Y'' axis; polishing the cutting surface to form a polished surface; and etching the polished surface. The method includes forming a first main surface and a second main surface of a quartz substrate, providing a first excitation electrode on the first main surface of the quartz substrate, and providing a second excitation electrode on the second main surface of the quartz substrate, wherein a plurality of first irregularities are provided in the region of the first main surface of the quartz substrate that overlaps with the first excitation electrode, and a plurality of second irregularities are provided in the region of the second main surface of the quartz substrate that overlaps with the second excitation electrode, and the first maximum dimension of the plurality of first irregularities in the thickness direction of the quartz substrate is different from the second maximum dimension of the plurality of second irregularities in the thickness direction.

[0009] According to the present invention, it is possible to provide a piezoelectric vibration element and a method for manufacturing the same that can improve productivity.

[0010] This is an exploded perspective view of a quartz oscillator according to the first embodiment. This is a cross-sectional view of a quartz oscillator along the line II-II according to the first embodiment. This is a plan view of a quartz oscillator element according to the first embodiment. This is a cross-sectional view of the vibrating part according to the first embodiment. This is a diagram illustrating the angle of the quartz substrate according to the first embodiment. This is a flowchart illustrating a part of the manufacturing method of a quartz oscillator element according to the first embodiment. This is a flowchart illustrating a part of the manufacturing method of a quartz oscillator element according to the first embodiment. This is a diagram illustrating the manufacturing method of a quartz oscillator element according to the first embodiment. This is a diagram illustrating the manufacturing method of a quartz oscillator element according to the first embodiment. This is a cross-sectional view of the vibrating part according to the second embodiment. This is a cross-sectional view of a quartz oscillator according to the third embodiment. This is a cross-sectional view of a quartz oscillator according to the fourth embodiment. This is a plan view of a quartz oscillator element according to the fifth embodiment. This is a diagram illustrating the manufacturing method of a quartz oscillator element according to the fifth embodiment. This is a cross-sectional view of a quartz oscillator according to the sixth embodiment. This is an intensity map of secondary vibrations in a comparative example of the sixth embodiment. This is an intensity map of secondary vibrations in the first embodiment of the sixth embodiment. This is an intensity map of secondary vibrations in the second embodiment of the sixth embodiment.

[0011] Embodiments of the present invention are described below. In the following drawings, identical or similar components are denoted by identical or similar reference numerals. The drawings are illustrative, and the dimensions and shapes of each part are schematic; the technical scope of the present invention should not be limited to these embodiments.

[0012] Each drawing may, for convenience, include a Cartesian coordinate system consisting of the X', Y'', and Z' axes to clarify the relationships between the drawings and to help understand the positional relationships of each component. The X', Y', and Z' axes correspond to each other in each drawing. The X', Y', and Z' axes correspond to the crystal axes of the quartz substrate 11, which will be described later. The X axis is the electrical axis (polarity axis) of the quartz, the Y axis is the mechanical axis of the quartz, and the Z axis is the optical axis of the quartz. The relationship between the X' axis and the X axis, the relationship between the Y axis and the Y'' axis, and the relationship between the Z axis and the Z' axis will be described later.

[0013] In the following explanation, the direction parallel to the X' axis is referred to as the "X'-axis direction," the direction parallel to the Y'' axis as the "Y''-axis direction," and the direction parallel to the Z' axis as the "Z'-axis direction." Furthermore, the direction of the arrowheads for the X', Y'', and Z' axes is referred to as "positive" or "+ (plus)," and the direction opposite to the arrowhead is referred to as "negative" or "- (minus)." For convenience, the +Y''-axis direction will be described as upward and the -Y''-axis direction as downward, but the vertical orientation of the quartz oscillator 10 and the quartz resonator 1 is not limited. Also, the plane specified by the X' and Z' axes will be referred to as the Z'X' plane, and the same applies to the planes specified by the other axes.

[0014] <First Embodiment> First, the configuration of the crystal oscillator 1 according to the first embodiment will be described with reference to Figures 1 to 5. Figure 1 is an exploded perspective view of the crystal oscillator 1 according to the first embodiment. Figure 2 is a cross-sectional view of the crystal oscillator 1 according to the first embodiment along the line II-II. Figure 3 is a plan view of the crystal oscillating element 10 according to the first embodiment. Figure 4 is a cross-sectional view of the vibrating part 110 according to the first embodiment. Figure 5 is a diagram for explaining the angle of the crystal substrate 11 according to the first embodiment.

[0015] Figure 2 is a cross-sectional view of the quartz oscillator 1 along the X'Y'' plane, showing the cross-sectional structure passing through the center of the vibrating section 110, which will be described later. Figure 3 shows the quartz oscillator 10 viewed from the positive Y'' axis side in a plan view. Figure 4 is an enlarged cross-sectional view of the vibrating section 110 along the X'Y'' plane. Figure 5 shows the relationship between the X axis and the X' axis, the relationship between the Y axis and the Y'' axis, and the relationship between the Z axis and the Z' axis.

[0016] As shown in Figure 1, the quartz oscillator 1 comprises a quartz oscillator element 10, a lower cover 20, an upper cover 30, a lower joint 40, and an upper joint 50. The lower cover 20, the quartz oscillator element 10, and the upper cover 30 are arranged in this order with a gap in the Y'' axis direction. Hereinafter, the Y'' axis direction in which the lower cover 20, the quartz oscillator element 10, and the upper cover 30 are stacked will be referred to as the "thickness direction". Of the lower cover 20 and the upper cover 30, one corresponds to an example of a first substrate, and the other corresponds to an example of a second substrate. Of the lower joint 40 and the upper joint 50, one corresponds to an example of a first joint, and the other corresponds to an example of a second joint.

[0017] The crystal oscillator 1 is used, for example, as a component of a temperature-compensated crystal oscillator (TCXO), a voltage-controlled crystal oscillator (VCXO), or an oven-controlled crystal oscillator (OCXO).

[0018] The quartz oscillator 10 is an electromechanical energy conversion element that converts electrical energy and mechanical energy mutually through the piezoelectric effect. As shown in Figure 1, the quartz oscillator 10 has a vibrating part 110, a holding part 120, and a support arm 130.

[0019] The vibrating section 110 is excited at a predetermined frequency based on the applied alternating voltage. The vibrating section 110 is held in a vibrating space provided between the lower cover 20 and the upper cover 30 so as to be able to vibrate. The main vibration of the vibrating section 110 is the thickness-shear vibration mode.

[0020] As shown in Figure 3, the shape of the vibrating part 110 when viewed in plan (hereinafter simply referred to as "plan view") of the Z'X' plane is rectangular. The vibrating part 110 has a pair of short sides 111A and 111B and a pair of long sides 111C and 111D. The pair of short sides 111A and 111B extend along the Z' axis direction and face each other in the X' axis direction. The pair of long sides 111C and 111D extend along the X' axis direction and face each other in the Z' axis direction. The short side 111A is located at the end of the vibrating part 110 on the negative X' axis side. The short side 111B is located at the end of the vibrating part 110 on the positive X' axis side. The long side 111C is located at the end of the vibrating part 110 on the positive Z' axis side. The long side 111D is located at the end of the vibrating part 110 on the negative Z' axis side.

[0021] Furthermore, the primary vibration of the vibrating part is not limited to the thickness sliding vibration mode, but may also be, for example, the thickness longitudinal vibration mode, the spreading vibration mode, the length vibration mode, or the bending vibration mode. Also, the planar shape of the vibrating part is not limited to a rectangular shape, but may be, for example, a square, polygonal, circular, elliptical, or a combination thereof.

[0022] The holding portion 120 is the part that holds the vibrating portion 110. As shown in Figures 1 and 2, the holding portion 120, together with the lower cover 20, the upper cover 30, the lower joint portion 40, and the upper joint portion 50, forms the vibration space of the vibrating portion 110. As shown in Figure 3, when viewed from above, the holding portion 120 is provided at a distance from the vibrating portion 110 and in a rectangular frame-shaped area surrounding the vibrating portion 110.

[0023] As shown in Figure 3, the holding portion 120 has frame portions 121A, 121B, 121C, and 121D. Each of the frame portions 121A to 121D is a part of a rectangular frame surrounding the vibrating portion 110. Frame portion 121A is provided on the negative X' axis side of the vibrating portion 110, frame portion 121B is provided on the positive X' axis side of the vibrating portion 110, frame portion 121C is provided on the positive Z' axis side of the vibrating portion 110, and frame portion 121D is provided on the negative Z' axis side of the vibrating portion 110. Frame portion 121A is provided at a distance from the short side 111A of the vibrating portion 110 in the X' axis direction and extends parallel to the short side 111A along the Z' axis direction. The frame portion 121B is provided at a distance from the short side 111B of the vibrating portion 110 in the X' axis direction and extends parallel to the short side 111B along the Z' axis direction. The frame portion 121C is provided at a distance from the long side 111C of the vibrating portion 110 in the Z' axis direction and extends parallel to the long side 111C along the X' axis direction. The frame portion 121D is provided at a distance from the long side 111D of the vibrating portion 110 in the Z' axis direction and extends parallel to the long side 111D along the X' axis direction.

[0024] The holding portion 120 is a frame that is continuous in the circumferential direction. The end of frame portion 121A on the positive Z' axis side is connected to the end of frame portion 121C on the negative X' axis side. The end of frame portion 121A on the negative Z' axis side is connected to the end of frame portion 121D on the negative X' axis side. The end of frame portion 121B on the positive Z' axis side is connected to the end of frame portion 121C on the positive X' axis side. The end of frame portion 121B on the negative Z' axis side is connected to the end of frame portion 121D on the positive X' axis side. Frame portions 121A and 121B face each other in the X' axis direction with the vibrating portion 110 in between. Frame portions 121C and 121D face each other in the Z' axis direction with the vibrating portion 110 in between.

[0025] Furthermore, the holding portion is not limited to a rectangular frame that is continuous in the circumferential direction, but may be provided in at least a part of the rectangular frame-shaped area surrounding the vibrating portion. The holding portion may be provided, for example, in a rail-like manner having two parallel frame portions.

[0026] The support arm 130 supports the vibrating part 110, and the holding part 120 holds the vibrating part 110. The support arm 130 connects the vibrating part 110 and the holding part 120. As shown in Figure 3, the planar shape of the support arm 130 is rectangular, with a long side extending along the X' axis and a short side extending along the Z' axis. The end of the support arm 130 on the negative X' axis side is connected to the center of the end of the short side 111B of the vibrating part 110 in the Z' axis direction. The end of the support arm 130 on the positive X' axis side is connected to the center of the frame part 121B of the holding part 120 in the Z' axis direction. The dimension of the support arm 130 along the Z' axis direction (hereinafter referred to as "width") is smaller than the width of the vibrating part 110.

[0027] The planar shape of the support arm, the manner of connection to the vibrating part and the holding part, the dimensions, and the number are not limited to those described above. The planar shape of the support arm may be rectangular with a short side extending along the X' axis and a long side extending along the Z' axis, or it may be polygonal, circular, elliptical, or a combination thereof. The planar shape of the support arm may be I-shaped, L-shaped, U-shaped, or a combination thereof. The support arm may be connected to a part of the short side of the vibrating part that is away from the center, to the center or a part of the long side of the vibrating part that is away from the center, or to a corner of the vibrating part. The support arm may be connected to the frame on the negative X' axis side, the frame on the positive Z' axis side, or the frame on the negative Z' axis side of the holding part. The width of the support arm may be approximately equal to the width of the vibrating part, or it may be greater than the width of the vibrating part. Multiple support arms may be provided for the piezoelectric vibrating element.

[0028] As shown in Figure 2, the lower cover 20 is positioned opposite the vibrating portion 110, holding portion 120, and support arm 130 of the quartz oscillator 10 at a distance in the Y'' axis direction. The lower cover 20 is provided in a flat plate shape. As shown in Figure 1, the planar shape of the lower cover 20 is substantially rectangular, having a pair of long sides extending along the X' axis direction and facing each other in the Z' axis direction, and a pair of short sides extending along the Z' axis direction and facing each other in the X' axis direction. More specifically, the planar shape of the lower cover 20 is octagonal, with the long sides and short sides connected at the corners by intersecting sides that extend in a direction that intersects both the long and short sides. The length of these intersecting sides is sufficiently smaller than the length of the short sides. In other words, diagonal cutouts are formed at the four corners of the lower cover 20 in plan view.

[0029] As shown in Figure 2, the top cover 30 is positioned opposite the bottom cover 20, with a gap in the Y'' axis direction relative to the vibrating portion 110, holding portion 120, and support arm 130 of the quartz oscillator 10. The top cover 30 is provided in a flat plate shape. As shown in Figure 1, when viewed from above, the top cover 30 has a pair of long sides extending along the X' axis direction and facing each other in the Z' axis direction, and a pair of short sides extending along the Z' axis direction and facing each other in the X' axis direction. The planar shape of the top cover 30 is rectangular.

[0030] The shape of the lower and upper covers is not limited to a flat plate shape. A cavity may be provided on at least one side of the lower and upper covers facing the quartz crystal oscillator 10 to secure the vibration space for the quartz crystal oscillator 10.

[0031] The lower joint 40 and the upper joint 50 are provided in a rectangular frame shape along the holding portion 120 of the quartz crystal oscillator 10. The lower joint 40 connects the holding portion 120 of the quartz crystal oscillator 10 to the end of the lower cover 20. The upper joint 50 connects the holding portion 120 of the quartz crystal oscillator 10 to the end of the upper cover 30. The lower joint 40 and the upper joint 50 are provided by an organic adhesive containing, for example, epoxy, vinyl, acrylic, urethane, or silicone resins.

[0032] The materials of the lower and upper joints are not limited to organic adhesives, but may also be inorganic adhesives such as silicon-based adhesives containing water glass, or calcium-based adhesives containing cement. The materials of the lower and upper joints may also be low-melting-point glass (e.g., lead borate-based or tin phosphate-based glass). The materials of the lower and upper joints may also be gold (Au), tin (Sn), copper (Cu), titanium (Ti), aluminum (Al), germanium (Ge), silicon (Si), or eutectic alloys containing at least one of these.

[0033] Next, the detailed configurations of the quartz oscillator 10, the lower cover 20, and the upper cover 30 will be described.

[0034] As shown in Figure 1, the quartz oscillator 10 comprises a quartz substrate 11, a first excitation electrode 14a, a second excitation electrode 14b, a first extraction electrode 15a, a second extraction electrode 15b, a first connecting electrode 16a, and a second connecting electrode 16b.

[0035] The quartz substrate 11 is a type of piezoelectric substrate made of a piezoelectric material that vibrates in response to an applied voltage. The quartz substrate 11 is continuously provided across the vibrating portion 110, the holding portion 120, and the support arm 130. In the Z'X' plane direction, the quartz substrate 11 extends over substantially the entire area of ​​the vibrating portion 110, the holding portion 120, and the support arm 130. The quartz substrate 11 is a thin quartz crystal with the Z'X' plane as its main surface. Of the lower surface of the quartz substrate 11 facing the lower cover 20 and the upper surface facing the upper cover 30, one surface is the first main surface of the quartz substrate 11, and the other surface is the second main surface of the quartz substrate 11. Of the first and second main surfaces, one main surface includes the upper surface 11A, upper surface 12A, and upper surface 13A, which will be described later, and the other main surface includes the lower surface 11B, lower surface 12B, and lower surface 13B, which will be described later.

[0036] As shown in Figure 5, the first and second main surfaces of the quartz substrate 11 are Z'X' planes perpendicular to the Y'' axis. The quartz substrate 11 is formed by cutting a synthetic quartz crystal, planarizing the cut surface by polishing, and then further planarizing the polished surface by etching to obtain a quartz plate (for example, a quartz wafer), which is then processed into individual pieces.

[0037] As shown in Figure 1, the planar shapes of the upper surface 11A and lower surface 11B of the quartz substrate 11 are, for example, rectangular in shape, having a long side parallel to the X' axis and a short side parallel to the Z' axis. The quartz substrate 11 is also plate-shaped with a thickness parallel to the Y'' axis. As shown in Figure 5, the X' axis, Y'' axis, and Z' axis are defined based on the crystal axes of the quartz. Specifically, the X' axis and Y' axis are axes obtained by rotating the X and Y axes, which are the crystal axes of the quartz, by a rotation angle φ, with the Z axis, which is the crystal axis of the quartz, as the axis of rotation. The Y'' axis and Z' axis are axes obtained by rotating the Y' axis and Z axis, which are the crystal axes of the quartz, by a rotation angle θ, with the X' axis as the axis of rotation.

[0038] When viewed from the positive direction of the Z-axis and considering counterclockwise as positive, it is desirable that the relationship 1 degree ≤ φ ≤ 14 degrees holds for the rotation angle φ. When 1 degree ≤ φ ≤ 14 degrees, the frequency-temperature curve shifts to the higher temperature side compared to the case where φ = 0 degrees, thus suppressing frequency changes in the high-temperature range. This allows the guaranteed temperature range of the quartz oscillator 10 to be extended to higher temperatures. Furthermore, the relationship 1 degree ≤ φ ≤ 14 degrees suppresses the decrease in the electromechanical coupling coefficient k, and the ESR value is kept low by suppressing secondary vibrations.

[0039] When viewed from the positive direction of the X' axis and counterclockwise rotation is considered positive, it is desirable that the relationship 30° ≤ θ ≤ 40° holds for the rotation angle θ. In the case of 30° ≤ θ ≤ 40°, the frequency-temperature curve rotates clockwise around the inflection point compared to the case where θ = 0°, thus suppressing frequency changes in the low and high temperature ranges. This allows the guaranteed temperature range of the quartz oscillator 10 to be extended to both the low and high temperature ranges. By setting 1° ≤ φ ≤ 14° and 30° ≤ θ ≤ 40°, the guaranteed temperature range of the quartz oscillator 10 can be further extended to the high temperature range.

[0040] The cut angle of the quartz substrate is not limited to the above. The cut angle of the quartz substrate may be, for example, AT cut, BT cut, CT cut, DT cut, ST cut, GT cut, or SC cut.

[0041] As shown in Figure 3, the planar shape of the quartz substrate 11 in the vibrating section 110 is rectangular, having a long side extending along the X' axis and a short side extending along the Z' axis. As shown in Figure 2, in the vibrating section 110, the quartz substrate 11 has an upper surface 11A provided on the upper cover 30 side and a lower surface 11B provided on the lower cover 20 side. The upper surface 11A and the lower surface 11B are a pair of main surfaces of the quartz substrate 11 in the vibrating section 110.

[0042] As shown in Figure 3, in plan view, the vibrating section 110 has a central section 117 and a peripheral section 118. The central section 117 is located in the center of the vibrating section 110, and the peripheral section 118 is located around the central section 117. In plan view, the peripheral section 118 surrounds the central section 117. The planar shape of the central section 117 is rectangular, with a long side extending along the X' axis and a short side extending along the Z' axis. The planar shape of the peripheral section 118 is a rectangular frame adjacent to all sides of the central section 117. The thickness of the quartz substrate 11 in the central section 117 is approximately equal to the thickness of the quartz substrate 11 in the peripheral section 118. In other words, in the vibrating section 110, the quartz substrate 11 is a flat plate of uniform thickness.

[0043] The planar shapes of the central and peripheral parts of the vibrating section are not limited to those described above. For example, the planar shape of the central part of the vibrating section may be polygonal, circular, elliptical, or a combination thereof. The planar shape of the peripheral part may be polygonal, circular, elliptical, or a combination thereof, and may be I-shaped adjacent to one side of the central part, L-shaped adjacent to two sides of the central part, or U-shaped adjacent to three sides of the central part. Furthermore, the relationship between the thickness of the central part and the thickness of the peripheral part of the vibrating section is not limited to those described above; the thickness of the central part may be greater than the thickness of the peripheral part, or the thickness of the central part may be less than the thickness of the peripheral part. For example, the vibrating section of the quartz substrate may be a mesa-type structure in which at least one of the upper and lower surfaces is convex in the central part, or an inverted mesa-type structure in which at least one of the upper and lower surfaces is concave in the central part. When the vibrating part has a mesa-type structure or an inverted mesa-type structure, the shape of the vibrating part may be a stepped shape in which the thickness of the quartz substrate changes discontinuously at the boundary between the central part and the peripheral part, a convex shape in which the amount of change in thickness changes continuously, or a bevel shape in which the amount of change in thickness changes discontinuously.

[0044] As shown in FIG. 3, the planar shape of the crystal substrate 11 in the holding portion 120 is a rectangular frame shape having a long side along the X'-axis direction and a short side along the Z'-axis direction. In the holding portion 120, the crystal substrate 11 has an upper surface 12A provided on the upper lid 30 side and a lower surface 12B provided on the lower lid 20 side. The upper surface 12A and the lower surface 12B are a pair of main surfaces of the crystal substrate 11 in the holding portion 120.

[0045] As shown in FIG. 2, the thickness of the crystal substrate 11 in the holding portion 120 is substantially equal to the thickness of the crystal substrate 11 in the vibrating portion 110. The thicknesses of the crystal substrate 11 in the frame portions 121A to 121D are substantially equal to each other. However, the thickness of the crystal substrate in the holding portion may be larger or smaller than the thickness of the crystal substrate in the vibrating portion.

[0046] As shown in FIG. 3, the planar shape of the crystal substrate 11 in the support arm 130 is a rectangular shape having a long side extending along the X'-axis direction and a short side extending along the Z'-axis direction. As shown in FIG. 2, in the support arm 130, the crystal substrate 11 has an upper surface 13A provided on the upper lid 30 side and a lower surface 13B provided on the lower lid 20 side. The upper surface 13A and the lower surface 13B are a pair of main surfaces of the crystal substrate 11 in the support arm 130.

[0047] As shown in FIG. 2, the thickness of the crystal substrate 11 in the support arm 130 is substantially equal to the thickness of the crystal substrate 11 in the vibrating portion 110 and is substantially equal to the thickness of the crystal substrate 11 in the holding portion 120. However, the thickness of the crystal substrate in the support arm may be larger or smaller than the thickness of the crystal substrate in the vibrating portion. Also, the thickness of the crystal substrate in the support arm may be larger or smaller than the thickness of the crystal substrate in the holding portion.

[0048] A plurality of concavo-convex portions are provided on the first main surface of the crystal substrate 11, and a plurality of concavo-convex portions are also provided on the second main surface of the crystal substrate 11. Here, the "plurality of concavo-convex portions" includes a plurality of concave portions, a plurality of convex portions, or both. Therefore, only a plurality of concave portions may be provided on the first main surface of the crystal substrate 11, or only a plurality of convex portions may be provided. The same applies to the second main surface of the crystal substrate 11.

[0049] The maximum dimension in the thickness direction of the quartz substrate 11 is 0.01 μm or more and 1 μm or less for the multiple irregularities provided on the first and second main surfaces of the quartz substrate 11. Here, "maximum dimension in the thickness direction" refers to the maximum height of the convex portion if all of the multiple irregularities are convex portions, and to the maximum depth of the concave portion if all of the multiple irregularities are concave portions. However, the "maximum value" here refers to the maximum value within a range excluding outliers, for example, the maximum value within the range of mean ± 2σ (σ is the standard deviation). If the multiple irregularities include both concave and convex portions, the larger of the maximum height of the convex portion and the maximum depth of the concave portion is the "maximum dimension in the thickness direction". Furthermore, as a method for measuring the height of these concave and convex portions, an atomic force microscope (AFM) may be used, which measures the surface shape by bringing a needle close to the sample surface and detecting the interatomic force acting between the needle and the sample. Alternatively, the optical height and surface accuracy of the cross-sectional structure may be measured after cross-sectional polishing.

[0050] As shown in Figure 2, the upper surface 11A of the quartz substrate 11 in the vibrating section 110 is provided with a plurality of irregularities 11Ar, and the lower surface 11B of the quartz substrate 11 in the vibrating section 110 is provided with a plurality of irregularities 11Br. The plurality of irregularities 11Ar includes a plurality of irregularities 17Ar provided in the central portion 117 of the upper surface 11A, which is the region overlapping with the first excitation electrode 14a, and a plurality of irregularities 18Ar provided in the peripheral portion 118 of the upper surface 11A, which is outside the region overlapping with the first excitation electrode 14a. The plurality of irregularities 11Br includes a plurality of irregularities 17Br provided in the central portion 117 of the lower surface 11B, which is the region overlapping with the second excitation electrode 14b, and a plurality of irregularities 18Br provided in the peripheral portion 118 of the lower surface 11B, which is outside the region overlapping with the second excitation electrode 14b. Multiple bumps 12Ar are provided on the upper surface 12A of the crystal substrate 11 in the holding portion 120, that is, the region that overlaps with the upper joint portion 50. Multiple bumps 12Br are provided on the lower surface 12B of the crystal substrate 11 in the holding portion 120, that is, the region that overlaps with the lower joint portion 40. Multiple bumps 13Ar are provided on the upper surface 13A of the crystal substrate 11 in the support arm 130, and multiple bumps 13Br are provided on the lower surface 13B of the crystal substrate 11 in the support arm 130.

[0051] The uneven surface 17Ar is an example of the first uneven surface, the uneven surface 17Br is an example of the second uneven surface, the uneven surface 18Ar or 13Ar is an example of the third uneven surface, and the uneven surface 12Ar is an example of the fourth or fifth uneven surface. However, the first to fifth uneven surfaces are not limited to those described above. For example, the uneven surface 17Ar may be the second uneven surface and the uneven surface 17Br may be the first uneven surface. Also, the uneven surface 18Br or 13Br may be the third uneven surface and the uneven surface 12Br may be the fourth or fifth uneven surface.

[0052] As shown in Figure 4, the maximum dimension Ta in the thickness direction of the plurality of bumps 11Ar provided on the upper surface 11A of the quartz substrate 11 in the vibrating unit 110 is greater than the maximum dimension Tb in the thickness direction of the plurality of bumps 11Br provided on the lower surface 11B of the quartz substrate 11 in the vibrating unit 110 (Tb < Ta). The maximum dimension of the plurality of bumps 11Ar in the thickness direction is preferably at least twice the maximum dimension of the plurality of bumps 11Br in the thickness direction (2 × Tb ≤ Ta), and more preferably at least three times (3 × Tb ≤ Ta). When the direction parallel to the upper surface 11A is defined as the in-plane direction, the maximum dimension Wa of the plurality of bumps 11Ar in the in-plane direction is greater than the maximum dimension Wb of the plurality of bumps 11Br in the in-plane direction (Wb < Wa). The maximum dimension Wa of the multiple irregularities 11Ar in the in-plane direction is preferably at least twice (2 × Wb ≤ Wa) and more preferably at least three times (3 × Wb ≤ Wa) the maximum dimension Wb of the multiple irregularities 11Br in the in-plane direction. Here, "maximum dimension in the in-plane direction" is the maximum length of the multiple irregularities in the direction parallel to the X'Z' plane. However, "maximum value" here is the maximum value within the range excluding outliers, similar to "maximum dimension in the thickness direction".

[0053] It is desirable that the average value of the dimensions of the multiple irregularities 11Ar in the thickness direction (hereinafter referred to as the "average dimension") be greater than the average dimension of the multiple irregularities 11Br in the thickness direction, and the same applies to the mode (hereinafter referred to as the "mode dimension") and the median (hereinafter referred to as the "median dimension") of the dimensions in the thickness direction. It is also desirable that the average dimension, mode dimension, and median dimension in the in-plane direction be greater for the multiple irregularities 11Ar than for the multiple irregularities 11Br. Hereafter, if a relationship of magnitude and equality regarding the maximum dimension holds between multiple irregularities of multiple types, it is desirable that the same relationship of magnitude and equality also holds for the average dimension, mode dimension, and median dimension.

[0054] Hereinafter, the maximum dimensions in the thickness direction of each of the multiple protrusions 11Ar, 17Ar, 18Ar, 13Ar, 12Ar, 11Br, 17Br, 18Br, 13Br, and 12Br will be denoted as T11Ar (=Ta), T17Ar, T18Ar, T13Ar, T12Ar, T11Br (=Tb), T17Br, T18Br, T13Br, and T12Br. Let W11Ar (=Wa), W17Ar, W18Ar, W13Ar, W12Ar, W11Br (=Wb), W17Br, W18Br, W13Br, and W12Br be the maximum dimensions in the in-plane direction of each of the multiple protrusions 11Ar, 17Ar, 18Ar, 13Ar, 12Ar, 11Br (=Wb), W17Br, W18Br, W13Br, and W12Br. The number of each of the multiple bumps and depressions 11Ar, 17Ar, 18Ar, 13Ar, 12Ar, 11Br, 17Br, 18Br, 13Br, and 12Br per unit area (hereinafter referred to as "number density") is denoted as N11Ar, N17Ar, N18Ar, N13Ar, N12Ar, N11Br, N17Br, N18Br, N13Br, and N12Br.

[0055] The maximum dimension T17Ar in the thickness direction of the multiple recesses 17Ar provided on the upper surface 11A in the central portion 117 is approximately equal to the maximum dimension T18Ar in the thickness direction of the multiple recesses 18Ar provided on the upper surface 11A in the peripheral portion 118 (T17Ar ≈ T18Ar). The maximum dimension T11Ar of the multiple recesses 11Ar consisting of multiple recesses 17Ar, 18Ar is equal to the larger of the maximum dimension T17Ar and the maximum dimension T18Ar, so the relationship T17Ar ≈ T18Ar ≈ T11Ar holds. The maximum dimension W17Ar in the in-plane direction of the multiple bumps 17Ar provided on the upper surface 11A in the central part 117 is approximately equal to the maximum dimension W18Ar in the in-plane direction of the multiple bumps 18Ar provided on the upper surface 11A in the peripheral part 118 (W17Ar ≈ W18Ar). The maximum dimension W11Ar of the multiple bumps 11Ar consisting of multiple bumps 17Ar, 18Ar is equal to the larger of the maximum dimension W17Ar and the maximum dimension W18Ar, so the relationship W17Ar ≈ W18Ar ≈ W11Ar holds. Similarly, the maximum dimension T17Br in the thickness direction of the multiple irregularities 17Br is approximately equal to the maximum dimension T18Br in the thickness direction of the multiple irregularities 18Br (T17Br ≈ T18Br ≈ T11Br), and the maximum dimension W17Br in the in-plane direction of the multiple irregularities 17Br is approximately equal to the maximum dimension W18Br of the multiple irregularities 18Br (W17Br ≈ W18Br ≈ W11Br).

[0056] For example, the number density N11Ar of the multiple bumps 11Ar provided on the upper surface 11A is approximately equal to the number density N11Br of the multiple bumps 11Br provided on the lower surface 11B (N11Ar ≈ N11Br). The number density N17Ar of the multiple bumps 17Ar provided on the upper surface 11A in the central part 117 is approximately equal to the number density N18Ar of the multiple bumps 18Ar provided on the upper surface 11A in the peripheral part 118 (N17Ar ≈ N18Ar). The number density N11Ar of the multiple bumps 11Ar consisting of multiple bumps 17Ar and 18Ar is the average of the number densities N17Ar and N18Ar, so the relationship N17Ar ≈ N18Ar ≈ N11Ar holds. The number density N17Br of the multiple bumps 17Br provided on the lower surface 11B in the central part 117 is approximately equal to the number density N18Br of the multiple bumps 18Br provided on the lower surface 11B in the peripheral part 118 (N17Br ≈ N18Br). The number density N11Br of the multiple bumps 11Br consisting of multiple bumps 17Br and 18Br is the average of the number densities N17Br and N18Br, so the relationship N17Br ≈ N18Br ≈ N11Br holds true. In the central portion 117, the number density N17Ar of the multiple irregularities 17Ar provided on the upper surface 11A is approximately equal to the number density N17Br of the multiple irregularities 17Br provided on the lower surface 11B in the central portion 117 (N17Ar ≈ N17Br), and in the peripheral portion 118, the number density N18Ar of the multiple irregularities 18Ar provided on the upper surface 11A is approximately equal to the number density N18Br of the multiple irregularities 18Br provided on the lower surface 11B in the peripheral portion 118 (N18Ar ≈ N18Br).

[0057] Furthermore, the number density N11Ar of multiple bumps 11Ar may be different from the number density N11Br of multiple bumps 11Br (N11Ar ≠ N11Br). Also, the number density N17Ar of multiple bumps 17Ar may be different from the number density N18Ar of multiple bumps 18Ar (N17Ar ≠ N18Ar), and the number density N17Br of multiple bumps 17Br may be different from the number density N18Br of multiple bumps 18Br (N17Br ≠ N18Br). The number density N17Ar of multiple irregularities 17Ar may be different from the number density N17Br of multiple irregularities 17Br (N17Ar ≠ N17Br), and the number density N18Ar of multiple irregularities 18Ar may be different from the number density N18Br of multiple irregularities 18Br (N18Ar ≠ N18Br).

[0058] The maximum dimension T13Ar in the thickness direction of the multiple bumps 13Ar provided on the upper surface 13A of the crystal substrate 11 in the support arm 130 is approximately equal to the maximum dimension T11Ar in the thickness direction of the multiple bumps 11Ar provided on the upper surface 11A of the crystal substrate 11 in the vibrating part 110 (T13Ar ≈ T11Ar ≈ T17Ar ≈ T18Ar). The maximum dimension T13Br in the thickness direction of the multiple bumps 13Br provided on the lower surface 13B of the crystal substrate 11 in the support arm 130 is approximately equal to the maximum dimension T11Br in the thickness direction of the multiple bumps 11Br provided on the lower surface 11B of the crystal substrate 11 in the vibrating part 110 (T13Br ≈ T11Br ≈ T17Br ≈ T18Br). The maximum dimension W13Ar of multiple irregularities 13Ar in the in-plane direction is approximately equal to the maximum dimension W11Ar of multiple irregularities 11Ar in the in-plane direction (W13Ar ≈ W11Ar ≈ W17Ar ≈ W18Ar). The maximum dimension W13Br of multiple irregularities 13Br in the in-plane direction is approximately equal to the maximum dimension W11Br of multiple irregularities 11Br in the in-plane direction (W13Br ≈ W11Br ≈ W17Br ≈ W18Br). The number density N13Ar of multiple irregularities 13Ar is approximately equal to the number density N11Ar of multiple irregularities 11Ar (N13Ar ≈ N11Ar ≈ N17Ar ≈ N18Ar). The number density N13Br of multiple irregularities 13Br is approximately equal to the number density N11Br of multiple irregularities 11Br (N13Br ≈ N11Br ≈ N17Br ≈ N18Br). The number density N13Ar of multiple irregularities 13Ar is approximately equal to the number density N13Br of multiple irregularities 13Br (N13Ar ≈ N13Br).

[0059] The maximum dimension T13Ar in the thickness direction of the multiple protrusions 13Ar may differ from the maximum dimension T11Ar in the thickness direction of the multiple protrusions 11Ar (T13Ar ≠ T11Ar). In this case, since the multiple protrusions 11Ar are composed of multiple protrusions 17Ar, 18Ar, the maximum dimension T13Ar will differ from the maximum dimensions T17Ar, T18Ar (T13Ar ≠ T17Ar, T13Ar ≠ T18Ar). The maximum dimension T13Br in the thickness direction of the multiple protrusions 13Br may differ from the maximum dimension T11Br in the thickness direction of the multiple protrusions 11Br (T13Br ≠ T11Br). In this case, since the multiple bumps 11Br are composed of multiple bumps 17Br and 18Br, the maximum dimension T13Br is different from the maximum dimensions T17Br and T18Br (T13Br ≠ T17Br, T13Br ≠ T18Br). Similarly, the maximum dimension W13Ar in the in-plane direction of the multiple bumps 13Ar may be different from the maximum dimension W11Ar in the in-plane direction of the multiple bumps 11Ar (W13Ar ≠ W11Ar, W13Ar ≠ W17Ar, W13Ar ≠ W18Ar). The maximum dimension W13Br of the multiple irregularities 13Br in the in-plane direction may differ from the maximum dimension W11Br of the multiple irregularities 11Br in the in-plane direction (W13Br ≠ W11Br, W13Br ≠ W17Br, W13Br ≠ W18Br). The number density N13Ar of the multiple irregularities 13Ar may differ from the number density N11Ar of the multiple irregularities 11Ar (N13Ar ≠ N11Ar). The number density N13Br of the multiple irregularities 13Br may differ from the number density N11Br of the multiple irregularities 11Br (N13Br ≠ N11Br).

[0060] The maximum dimension T12Ar in the thickness direction of the multiple bumps 12Ar provided on the upper surface 12A of the crystal substrate 11 in the holding part 120 is greater than the maximum dimension T11Ar in the thickness direction of the multiple bumps 11Ar provided on the upper surface 11A of the crystal substrate 11 in the vibrating part 110 (T11Ar < T12Ar). Since the multiple bumps 11Ar consist of multiple bumps 17Ar and 18Ar, and the relationship T17Ar ≈ T18Ar ≈ T11Ar holds, the maximum dimension T12Ar in the thickness direction of the multiple bumps 12Ar is greater than the maximum dimensions T17Ar and T18Ar of the multiple bumps 17Ar and 18Ar in the thickness direction, respectively (T17Ar < T12Ar, T18Ar < T12Ar). The maximum dimension T12Br in the thickness direction of the multiple bumps 12Br provided on the lower surface 12B of the crystal substrate 11 in the holding part 120 is greater than the maximum dimension T11Br in the thickness direction of the multiple bumps 11Br provided on the lower surface 11B of the crystal substrate 11 in the vibrating part 110 (T11Br < T12Br). The multiple bumps 11Br consist of multiple bumps 17Br and 18Br, and the relationship T17Br ≈ T18Br ≈ T11Br holds true, so the maximum dimension T12Br in the thickness direction of the multiple bumps 12Br is greater than the maximum dimensions T17Br and T18Br of the multiple bumps 17Br and 18Br in the thickness direction, respectively (T17Br < T12Br, T18Br < T12Br).

[0061] The maximum dimension T12Ar in the thickness direction of the multiple protrusions 12Ar is greater than both the maximum dimension T17Ar in the thickness direction of the multiple protrusions 17Ar and the maximum dimension T17Br in the thickness direction of the multiple protrusions 17Br (T17Br < T17Ar < T12Ar). Similarly, the maximum dimension T12Ar in the thickness direction of the multiple protrusions 12Ar is greater than both the maximum dimension T18Ar in the thickness direction of the multiple protrusions 18Ar and the maximum dimension T18Br in the thickness direction of the multiple protrusions 18Br (T18Br < T18Ar < T12Ar). The same relationships T17Br < T17Ar < T12Br and T18Br < T18Ar < T12Br hold for the maximum dimension T12Br in the thickness direction of the multiple protrusions 12Br.

[0062] The maximum dimension T12Ar of the multiple recesses 12Ar only needs to be greater than at least one of the maximum dimension T17Ar of the multiple recesses 17Ar and the maximum dimension T17Br of the multiple recesses 17Br. For example, the relationship T17Br < T12Ar ≤ T17Ar may hold. Similarly, the maximum dimension T12Br of the multiple recesses 12Br only needs to be greater than at least one of the maximum dimension T17Ar of the multiple recesses 17Ar and the maximum dimension T17Br of the multiple recesses 17Br, for example, the relationship T17Br < T12Br ≤ T17Ar may hold. The maximum dimension T12Ar of the multiple recesses 12Ar is, for example, approximately equal to the maximum dimension T12Br of the multiple recesses 12Br (T12Ar ≈ T12Br), but the relationships T12Ar < T12Br or T12Br < T12Ar may also hold.

[0063] Furthermore, the maximum dimension T12Ar of the multiple protrusions 12Ar may be approximately equal to the maximum dimension T17Ar of the multiple protrusions 17Ar (T12Ar ≈ T17Ar), and may be approximately equal to the maximum dimension T18Ar of the multiple protrusions 18Ar (T12Ar ≈ T18Ar). Also, the maximum dimension T12Br of the multiple protrusions 12Br may be approximately equal to the maximum dimension T17Br of the multiple protrusions 17Br (T12Br ≈ T17Br), and may be approximately equal to the maximum dimension T18Br of the multiple protrusions 18Br (T12Br ≈ T18Br).

[0064] The maximum dimension W12Ar in the in-plane direction of multiple irregularities 12Ar is greater than the maximum dimension W11Ar in the in-plane direction of multiple irregularities 11Ar (W11Ar < W12Ar). The maximum dimension W12Br in the in-plane direction of multiple irregularities 12Br is greater than the maximum dimension W11Br in the in-plane direction of multiple irregularities 11Br (W11Br < W12Br). The number density N12Ar of multiple irregularities 12Ar is approximately equal to the number density N11Ar of multiple irregularities 11Ar (N11Ar ≈ N12Ar). The number density N12Br of multiple irregularities 12Br is approximately equal to the number density N11Br of multiple irregularities 11Br (N12Br ≈ N11Br). The number density N12Ar of multiple irregularities 12Ar is approximately equal to the number density N12Br of multiple irregularities 12Br (N12Ar ≈ N12Br).

[0065] Furthermore, the maximum dimension T12Ar in the thickness direction of the multiple protrusions 12Ar may be less than or equal to the maximum dimension T11Ar in the thickness direction of the multiple protrusions 11Ar (T12Ar ≤ T11Ar). The maximum dimension T12Br in the thickness direction of the multiple protrusions 12Br may be less than or equal to the maximum dimension T11Br in the thickness direction of the multiple protrusions 11Br (T12Br ≤ T11Br). The maximum dimension W12Ar in the in-plane direction of the multiple protrusions 12Ar may be less than or equal to the maximum dimension W11Ar in the in-plane direction of the multiple protrusions 11Ar (W12Ar ≤ W11Ar). The maximum dimension W12Br in the in-plane direction of the multiple protrusions 12Br may be less than or equal to the maximum dimension W11Br in the in-plane direction of the multiple protrusions 11Br (W12Br ≤ W11Br). The number density N12Ar of multiple irregularities 12Ar may be different from the number density N11Ar of multiple irregularities 11Ar (N12Ar ≠ N11Ar). The number density N12Br of multiple irregularities 12Br may be different from the number density N11Br of multiple irregularities 11Br (N12Br ≠ N11Br).

[0066] The first excitation electrode 14a and the second excitation electrode 14b apply an alternating voltage to the crystal substrate 11 of the vibrating section 110 to excite the vibrating section 110. As shown in Figures 2 and 3, the first excitation electrode 14a and the second excitation electrode 14b are located in the central part 117 of the vibrating section 110. The first excitation electrode 14a is located on the upper surface 11A of the crystal substrate 11 in the vibrating section 110, and the second excitation electrode 14b is located on the lower surface 11B of the crystal substrate 11 in the vibrating section 110. The first excitation electrode 14a and the second excitation electrode 14b face each other in the Y'' axis direction with the crystal substrate 11 in between. As shown in Figure 3, the planar shape of the first excitation electrode 14a and the second excitation electrode 14b is rectangular, and they are arranged so that their entire halves overlap each other.

[0067] The first excitation electrode may be provided on the lower surface of the quartz substrate, and the second excitation electrode may be provided on the upper surface of the quartz substrate. The planar shapes of the first and second excitation electrodes are not limited to rectangular. The planar shapes of the first and second excitation electrodes may be polygonal, circular, elliptical, or a combination thereof. Furthermore, the planar shape of the first excitation electrode is not limited to being the same as that of the second excitation electrode, and the planar shapes of the first and second excitation electrodes may be different from each other. When viewed from above, the area of ​​the first excitation electrode is, for example, approximately equal to the area of ​​the second excitation electrode, but may be different from the area of ​​the second excitation electrode.

[0068] The first lead electrode 15a electrically connects the first excitation electrode 14a and the first connecting electrode 16a. As shown in Figure 1, the first lead electrode 15a, which is led out from the first excitation electrode 14a, extends over the peripheral portion 118 of the vibrating part 110, the support arm 130, and the frame portion 121B of the holding part 120, and is electrically connected to the first connecting electrode 16a. The second lead electrode 15b, which is led out from the second excitation electrode 14b, extends over the peripheral portion 118 of the vibrating part 110, the support arm 130, and the frame portions 121B and 121D of the holding part 120, and is electrically connected to the second connecting electrode 16b.

[0069] As shown in Figure 3, in the peripheral portion 118 of the vibrating section 110, the first lead electrode 15a is provided on the upper surface 11A. In the support arm 130, the first lead electrode 15a is provided on the upper surface 13A, the lower surface 13B, and the left side facing the frame portion 121C. In the frame portion 121B of the holding section 120, the first lead electrode 15a is provided on the upper surface 12A, the lower surface 12B, and the inner surface facing the vibrating section 110. As shown in Figure 3, in the peripheral portion 118 of the vibrating section 110, the second lead electrode 15b is provided on the lower surface 11B. In the support arm 130, the second lead electrode 15b is provided on the upper surface 13A, the lower surface 13B, and the right side facing the frame portion 121D. In the frame portions 121B and 121D of the holding portion 120, the second lead electrode 15b is provided on the upper surface 12A, the lower surface 12B, and the inner surface facing the vibrating portion 110. As shown in Figure 3, in a plan view, the first lead electrode 15a and the second lead electrode 15b do not overlap with each other and are separated.

[0070] The first connecting electrode 16a electrically connects the first excitation electrode 14a to an external terminal, and the second connecting electrode 16b electrically connects the second excitation electrode 14b to an external terminal. As shown in Figure 1, the first connecting electrode 16a is located at the corner of the holding portion 120 where the frame portion 121B and the frame portion 121C are connected, and is provided on the lower surface 12B of the crystal substrate 11. The second connecting electrode 16b is located at the corner of the holding portion 120 where the frame portion 121A and the frame portion 121D are connected, and is provided on the lower surface 12B of the crystal substrate 11.

[0071] The first excitation electrode 14a, the first extraction electrode 15a, and the first connecting electrode 16a are integrally provided. The same applies to the second excitation electrode 14b, the second extraction electrode 15b, and the second connecting electrode 16b. These electrodes of the quartz oscillator 10 are, for example, single-layer structures made of aluminum (Al) layers, but are not limited thereto. The electrodes of the quartz oscillator may also be multilayer structures in which a base layer and a surface layer are stacked in that order. For example, the base layer is a chromium (Cr) layer with good adhesion to the quartz substrate, and the surface layer is a gold (Au) layer with good chemical stability. The electrodes of the quartz oscillator may also include silver (Ag), copper (Cu), titanium (Ti), tantalum (Ta), molybdenum (Mo), titanium-tungsten alloy (TiW), or aluminum-copper alloy (AlCu).

[0072] The lower cover 20 has a crystal substrate 21, power terminals ST1 and ST2, and dummy terminals DT1 and DT2. The crystal substrate 21 is a flat substrate that overlaps substantially the entire crystal oscillator 10 in a plan view. The crystal substrate 21 is formed of a crystal crystal with the same cut angle as the crystal substrate 11 of the crystal oscillator 10. This reduces thermal stress caused by differences in the coefficient of thermal expansion and the direction of thermal expansion between the crystal oscillator 10 and the lower cover 20, thereby suppressing fluctuations in the frequency of the crystal oscillator 10. The crystal substrate 21 has an upper surface 21A provided on the side of the crystal oscillator 10 and a lower surface 21B provided on the opposite side of the upper surface 21A. When viewed from above, the crystal substrate 21 has a long side extending along the X' axis and a short side extending along the Z' axis. A notch is formed at the corner where the short side and the long side of the crystal substrate 21 connect. The area of ​​the crystal substrate 21 in a plan view is smaller than the area of ​​the crystal substrate 31 in a plan view, as described later, by the amount of this notch. The shape of the side surface formed by the notch at the corner of the crystal substrate 21 is, for example, planar. However, the shape of the side surface at the corner of the crystal substrate 21 is not limited to this, and may be a cylindrical, elliptical, sphere, or curved surface that is part of an ellipsoid, a prism, or a bent surface that is part of a polyhedron, or a combination thereof.

[0073] Power terminals ST1, ST2 and dummy terminals DT1, DT2 are provided on the lower surface 21B of the crystal substrate 21. Power terminals ST1, ST2 and dummy terminals DT1, DT2 correspond to examples of external terminals of the crystal oscillator 1. Power terminals ST1 and ST2 are for supplying a drive signal (drive voltage) to the crystal oscillator 1. Power terminal ST1 is electrically connected to the first connecting electrode 16a via a side electrode provided in a notch at the corner on the positive X' axis and positive Z' axis side of the crystal substrate 21. Power terminal ST2 is electrically connected to the second connecting electrode 16b via a side electrode provided in a notch at the corner on the negative X' axis and negative Z' axis side of the crystal substrate 21. Dummy terminals DT1 and DT2 are provided to balance electrical characteristics such as capacitance and mechanical strength between them and power terminals ST1 and ST2. The dummy terminals DT1 and DT2 are so-called floating electrodes that are not electrically connected to the crystal oscillator element 10.

[0074] At least one of the dummy terminals DT1 and DT2 may be a grounding electrode that electrically grounds a portion of the crystal oscillator 1.

[0075] The top cover 30 has a quartz substrate 31. The quartz substrate 31 is a flat substrate that overlaps substantially the entire quartz oscillator 10 in a plan view. The quartz substrate 31 is formed of quartz crystals with the same cut angle as the quartz substrate 11 of the quartz oscillator 10. This reduces thermal stress caused by differences in thermal expansion coefficients and directions of thermal expansion between the quartz oscillator 10 and the top cover 30, thereby suppressing fluctuations in the frequency of the quartz oscillator 10. The quartz substrate 31 has a lower surface 31B provided on the side of the quartz oscillator 10 and an upper surface 31A provided on the opposite side from the lower surface 31B. The planar shape of the quartz substrate 31 is rectangular, with a long side extending along the X' axis and a short side extending along the Z' axis.

[0076] Furthermore, the cut angles of the crystal substrates in the lower and upper covers are not particularly limited and may differ from those of the crystal substrate of the crystal oscillator. In addition, the lower and upper covers may have glass substrates, silicon substrates, ceramic substrates, metal substrates, or composite substrates combining these instead of crystal substrates.

[0077] Next, a method for manufacturing a quartz oscillator 10 according to one embodiment of the present invention will be described with reference to Figures 6 to 10. Figures 6 and 7 are flowcharts showing a part of the method for manufacturing a quartz oscillator according to one embodiment of the present invention. Figures 8 to 10 are diagrams illustrating the method for manufacturing a quartz oscillator according to the first embodiment.

[0078] First, prepare the quartz crystal XT0 (S10). The quartz crystal XT0 is a quartz crystal cut in the XY plane perpendicular to the Z axis.

[0079] Next, the X' and Y' axes of the crystal XT0 are identified (S20), and the crystal XT0 is cut using the ZX' and Y'Z planes (S30).

[0080] Specifically, first, the quartz crystal XT0 is placed on the rotating stage so that one XY plane is in contact with the mounting surface of the rotating stage and the other XY plane is facing upward. Next, using the other XY plane as the measurement plane, the crystal orientation of the quartz crystal XT0 is measured by an X-ray orientation measuring device, while the rotating stage is rotated around a rotation axis perpendicular to the mounting surface as the center of rotation. This determines the X' axis direction and Y' axis direction of the quartz crystal XT0. Next, the quartz crystal XT0 on the rotating stage is cut along the X' axis and Y' axis by the blade of a quartz cutting device provided perpendicular to the mounting surface of the rotating stage. This results in the cutting of quartz crystal XT1 from quartz crystal XT0, as shown in Figure 8. Note that in step S30, it is sufficient that the quartz crystal XT0 is cut on the Y'Z plane, which will be the measurement surface of the X-ray orientation measuring device in the subsequent step S40; it is not necessary to cut the quartz crystal XT0 on the ZX' plane. For details on this quartz crystal orientation measurement and cutting process, see W. L. Bond and J. A. You can refer to the paper "MAKING DOUBLY ROTATED QUARTZ PLATES" (added to IEEE Xploe on December 5, 2005), published by Kusters at the 31st Annual Symposium on Frequency Control (June 1-3, 1977), and the numerical values ​​of the rotation angle in this embodiment were measured in accordance with that paper.

[0081] Next, the Y'' and Z' axes of the crystal XT1 are identified (S40), and the crystal XT1 is cut using the X'Y'' and Z'X' planes (S50).

[0082] Specifically, similar to step S20, the crystal XT1 is placed on the rotating stage so that one Y'Z plane is in contact with the mounting surface of the rotating stage, and the crystal orientation of the crystal XT1 is measured using an X-ray orientation measuring device with the other Y'Z plane as the measuring plane, thereby determining the Y'' axis direction and Z' axis direction of the crystal XT1. Then, the crystal XT1 on the rotating stage is cut along the Y'' axis and Z' axis. Multiple cut surfaces along the Z' axis are provided at equal intervals in the Y'' axis direction, with intervals slightly larger than the thickness of the crystal substrate 11 that will be ultimately manufactured. As a result, multiple crystals XT2 are cut out from the crystal XT1, as shown in Figure 9. Note that in step S50, it is sufficient that the crystal XT1 is cut along the Z'X' plane, which is the main surface of the crystal substrate 11, and it is not necessary to cut the crystal XT0 along the X'Y'' plane.

[0083] Next, the cut surface is polished (S60). Specifically, the entire Z'X' face of the quartz XT2 cut in step S50 is subjected to chemical mechanical polishing to form a polished surface. This improves the flatness of the Z'X' face of the quartz XT2.

[0084] Next, the polished surface is etched (S70). Specifically, the entire Z'X' surface of the quartz XT2 polished in step S60 is wet-etched using BHF (Buffered Hydrogen Fluoride) as the etching solution. This further improves the flatness of the Z'X' surface of the quartz XT2. The first main surface and the second main surface of the quartz substrate 11 are formed by the etching process.

[0085] At this time, based on the crystal orientation of the quartz XT2, a plurality of irregularities 11Ar, 11Br, 12Ar, 12Br, 13Ar, 13Br are formed on the Z'X' surface of the quartz XT2, which are smaller than the irregularities of the polished surface. The dimensions of these irregularities can be adjusted to a desired size by adjusting conditions such as the composition of the etching solution, the processing time, and the number of processing cycles. For example, by making the time during which the etching solution is in contact with the Z'X' surface on the upper surfaces 11A, 12A, 13A of the quartz substrate 11 longer than the time during which the etching solution is in contact with the Z'X' surface on the lower surfaces 11B, 12B, 13B of the quartz substrate 11, the plurality of irregularities provided on the upper surfaces 11A, 12A, 13A can be made larger than the plurality of irregularities provided on the lower surfaces 11B, 12B, 13B. Furthermore, for example, the multiple irregularities on the upper surface 13A may be made larger than those on the upper surfaces 11A and 12A by wet etching the upper surfaces 11A, 12A, and 13A once, and then wet etching the upper surface 13A one or more times.

[0086] Next, the outer shape of the crystal substrate 11 is formed (S80). Specifically, first, as shown in Figure 10, dicing lines DL1 and DL2 are set. Dicing line DL1 is the short side of the crystal substrate 11, and dicing line DL2 is the long side of the crystal substrate 11. The crystal XT2 is positioned such that dicing line DL1 is parallel to the Z' axis and dicing line DL2 is parallel to the X' axis. Next, the crystal between the part where the vibrating part 110 is provided and the part where the support arm 130 is provided is removed by etching, and the crystal between the part where the holding part 120 is provided and the part where the support arm 130 is provided is removed. The outer shape of multiple crystal substrates 11 arranged in a matrix is ​​formed inside the crystal XT2.

[0087] Next, electrodes are provided (S90). First, a metal film is deposited on the entire surface of the quartz XT2. A photoresist is placed on this metal film, the photoresist is patterned, and the portion of the metal film exposed from the photoresist is removed by etching. As a result, a first excitation electrode 14a, a second excitation electrode 14b, a first extraction electrode 15a, a second extraction electrode 15b, a first connecting electrode 16a, and a second connecting electrode 16b are provided on each portion of the quartz XT2 that will become the quartz substrate 11.

[0088] Finally, the crystal XT2 is cut (S100). The crystal XT2 is cut along the dicing line DL1, which extends parallel to the Z' axis and is aligned in the X' axis direction, and the dicing line DL2, which extends parallel to the X' axis and is aligned in the Z' axis direction, thereby dividing it into multiple crystal oscillators 10.

[0089] As described above, in one embodiment of this invention, a plurality of irregularities 17Ar are provided in the region of the upper surface 11A that overlaps with the first excitation electrode 14a, and a plurality of irregularities 17Br are provided in the region of the lower surface 11B that overlaps with the second excitation electrode 14b. The maximum dimension T17Ar (=Ta) of the plurality of irregularities 17Ar in the thickness direction is greater than the maximum dimension T17Br (=Tb) of the plurality of irregularities 17Br in the thickness direction.

[0090] According to this, the surface structure of the upper surface 11A in the central portion 117 becomes more complex and the surface area of ​​the upper surface 11A increases due to the provision of multiple irregularities 17Ar, thereby improving the adhesion strength of the first excitation electrode 14a to the quartz substrate 11. Similarly, the adhesion strength of the second excitation electrode 14b to the quartz substrate 11 is improved by the provision of multiple irregularities 17Br. Therefore, damage due to electrode peeling of the quartz oscillator 10 can be suppressed and the reliability of the quartz oscillator 1 can be improved.

[0091] Furthermore, because the maximum dimension T17Ar (=Ta) is larger than the maximum dimension T17Br (=Tb), the suitability of laser processing on the second excitation electrode 14b can be improved compared to the suitability of laser processing on the first excitation electrode 14a. Specifically, when a laser is incident on the second excitation electrode 14b, which has small irregularities, the diffuse reflection of the laser can be suppressed compared to when a laser is incident on the first excitation electrode 14a, which has large irregularities. Therefore, when adjusting the frequency by trimming the second excitation electrode 14b with laser processing, the occurrence of defective products due to unwanted processing of areas caused by laser reflection is suppressed.

[0092] Furthermore, because the maximum dimension T17Ar (=Ta) is larger than the maximum dimension T17Br (=Tb), the processing rate and processing accuracy of ion beam processing can be appropriately adjusted. Specifically, by irradiating the first excitation electrode 14a, which has large irregularities, the processing rate can be improved compared to when the ion beam is irradiated onto the second excitation electrode 14b, which has small irregularities. Also, by irradiating the second excitation electrode 14b, which has small irregularities, the processing accuracy can be improved compared to when the ion beam is irradiated onto the first excitation electrode 14a, which has large irregularities. Therefore, the target to which the ion beam is irradiated can be selected from the first excitation electrode 14a and the second excitation electrode 14b according to the purpose. Specifically, when adjusting the frequency by trimming processing using ion beam processing, the first excitation electrode 14a can be ion beam processed when a high frequency adjustment speed is desired, and the second excitation electrode 14b can be ion beam processed when a high frequency adjustment accuracy is desired.

[0093] Based on the above, this embodiment provides a quartz oscillator 1 that can improve productivity.

[0094] In one embodiment described above, the maximum dimension T17Ar (=Ta) in the thickness direction of the multiple irregularities 17Ar is at least twice the maximum dimension T17Br (=Tb) in the thickness direction of the multiple irregularities 17Br.

[0095] According to this, the suitability of laser processing for the second excitation electrode 14b can be further improved. In addition, the adjustment of the processing rate and processing accuracy of ion beam processing can be made even easier.

[0096] In one embodiment described above, the lower joint 40 and the upper joint 50 are made of resin. The maximum dimension T12Ar in the thickness direction of the plurality of protrusions 12Ar provided on the upper lid 30 side of the holding part 120 is greater than the maximum dimension T11Ar in the thickness direction of the plurality of protrusions 11Ar provided on the upper lid 30 side of the vibrating part 110. In other words, the maximum dimension T12Ar is greater than the maximum dimension T17Ar in the thickness direction of the plurality of protrusions 17Ar. The maximum dimension T12Br in the thickness direction of the plurality of protrusions 12Br provided on the lower lid 20 side of the holding part 120 is greater than the maximum dimension T11Br in the thickness direction of the plurality of protrusions 11Br provided on the lower lid 20 side of the vibrating part 110. In other words, the maximum dimension T12Br is greater than the maximum dimension T17Br in the thickness direction of the plurality of protrusions 17Br. The maximum dimension T12Ar is greater than at least one of the maximum dimension T17Ar and the maximum dimension T17Br. The maximum dimension T12Br is greater than at least one of the maximum dimensions T17Ar and T17Br.

[0097] According to this, the surface structure of the upper surface 12A of the holding portion 120 is made more complex by the provision of multiple protrusions 12Ar, and the surface area of ​​the upper surface 12A is increased, thereby improving the adhesion strength of the upper joint portion 50 to the holding portion 120. This improves the adhesion strength between the quartz oscillator 10 and the upper cover 30. Similarly, the adhesion strength of the lower joint portion 40 to the holding portion 120 is improved by the provision of multiple protrusions 12Br, thereby improving the adhesion strength between the quartz oscillator 10 and the lower cover 20. The maximum dimension T12Ar of the multiple protrusions 12Ar is larger than the maximum dimension T11Ar of the multiple protrusions 11Ar, which further improves the adhesion strength of the upper joint portion 50 to the holding portion 120. Similarly, the maximum dimension T12Br is larger than the maximum dimension T11Ar, which further improves the adhesion strength of the lower joint portion 40 to the holding portion 120.

[0098] In one embodiment described above, the maximum dimension T17Ar (=Ta) in the thickness direction of the multiple irregularities 17Ar, and the maximum dimension T17Br (=Tb) in the thickness direction of the multiple irregularities 17Br are 0.01 μm or more and 1 μm or less.

[0099] According to this, by setting the maximum dimensions T17Ar (=Ta) and T17Br (=Tb) to 0.01 μm or more, the adhesion strength of the first excitation electrode 14a and the second excitation electrode 14b to the quartz substrate 11 can be sufficiently improved. Furthermore, by setting the maximum dimensions T17Ar (=Ta) and T17Br (=Tb) to 1 μm or less, step breaks at multiple irregularities 17Ar of the first excitation electrode 14a and step breaks at multiple irregularities 17Br of the second excitation electrode 14b can be suppressed.

[0100] Furthermore, a method for manufacturing a quartz oscillator 10 according to one aspect of this embodiment includes: preparing a quartz crystal XT0; identifying the X' axis and Y' axis by rotating the X and Y axes of the quartz crystal XT0 by a rotation angle φ with the Z axis as the axis of rotation; cutting the quartz crystal XT0 with a plane perpendicular to the X' axis; identifying the Y'' axis and Z' axis by rotating the Y' axis and Z axis of the quartz crystal XT1 by a rotation angle θ with the X' axis as the axis of rotation; cutting the quartz crystal XT1 with a cut surface perpendicular to the Y'' axis; polishing the cut surface of the quartz crystal XT2; and etching the polished surface to form the first main surface and the second main surface of the quartz substrate 11. A plurality of irregularities 17Ar are provided in the region of the upper surface 11A that overlaps with the first excitation electrode 14a, and a plurality of irregularities 17Br are provided in the region of the lower surface 11B that overlaps with the second excitation electrode 14b. The maximum dimension T17Ar (=Ta) in the thickness direction of the multiple irregularities 17Ar is greater than the maximum dimension T17Br (=Tb) in the thickness direction of the multiple irregularities 17Br.

[0101] According to this, the surface structure of the upper surface 11A in the central portion 117 becomes more complex and the surface area of ​​the upper surface 11A increases due to the provision of multiple irregularities 17Ar, thereby improving the adhesion strength of the first excitation electrode 14a to the quartz substrate 11. Similarly, the adhesion strength of the second excitation electrode 14b to the quartz substrate 11 is improved by the provision of multiple irregularities 17Br. Therefore, damage due to electrode peeling of the quartz oscillator 10 can be suppressed and the reliability of the quartz oscillator 1 can be improved.

[0102] Furthermore, because the maximum dimension T17Ar (=Ta) is larger than the maximum dimension T17Br (=Tb), the suitability of laser processing for the second excitation electrode 14b can be further improved than that for the first excitation electrode 14a. Specifically, when a laser is incident on the second excitation electrode 14b, which has small irregularities, the diffuse reflection of the laser can be suppressed compared to when a laser is incident on the first excitation electrode 14a, which has large irregularities. Therefore, when adjusting the frequency by trimming the second excitation electrode 14b with laser processing, the occurrence of defective products due to unwanted processing of areas caused by laser reflection is suppressed.

[0103] Furthermore, because the maximum dimension T17Ar (=Ta) is larger than the maximum dimension T17Br (=Tb), the processing rate and processing accuracy of ion beam processing can be appropriately adjusted. Specifically, by irradiating the first excitation electrode 14a, which has large irregularities, the processing rate can be improved compared to when the ion beam is irradiated onto the second excitation electrode 14b, which has small irregularities. Also, by irradiating the second excitation electrode 14b, which has small irregularities, the processing accuracy can be improved compared to when the ion beam is irradiated onto the first excitation electrode 14a, which has large irregularities. Therefore, the target to which the ion beam is irradiated can be selected from the first excitation electrode 14a and the second excitation electrode 14b according to the purpose. Specifically, when adjusting the frequency by trimming processing using ion beam processing, the first excitation electrode 14a can be ion beam processed when a high frequency adjustment speed is desired, and the second excitation electrode 14b can be ion beam processed when a high frequency adjustment accuracy is desired.

[0104] Based on the above, this embodiment provides a quartz oscillator 1 that can improve productivity.

[0105] In one embodiment described above, etching the polished surface involves wet etching the entire surface of the region where the first excitation electrode 14a is provided and the region where the second excitation electrode 14b is provided, and the multiple irregularities 17Ar and multiple irregularities 17Br are formed by etching.

[0106] According to this method, multiple recesses 17Ar and multiple recesses 17Br, each having a different maximum dimension in the thickness direction, can be created simultaneously without adding any manufacturing steps. Furthermore, the size of the multiple recesses 17Ar and multiple recesses 17Br can be easily adjusted by appropriately setting the etching conditions.

[0107] Furthermore, the process of providing multiple irregularities 17Ar and multiple irregularities 17Br on the quartz substrate 11 is not limited to a method of wet etching the upper surface 11A and the lower surface 11B under the same conditions. For example, in order to provide multiple irregularities of different sizes on the upper surface 11A and the lower surface 11B, the concentration of the etching solution in contact with the upper surface 11A and the lower surface 11B, and the etching processing time for the upper surface 11A and the lower surface 11B may be different. Also, the etching process may be performed with impurities deliberately attached to at least one of the upper surface 11A and the lower surface 11B. In addition, a roughening treatment such as patterning or sandblasting may be performed on at least one of the upper surface 11A and the lower surface 11B.

[0108] In one embodiment described above, the first lead electrode 15a is provided across the upper surface 11A of the peripheral portion 118 which is provided with a plurality of irregularities 18Ar, the upper surface 13A of the support arm 130 which is provided with a plurality of irregularities 13Ar, the lower surface 13B of the support arm 130 which is provided with a plurality of irregularities 13Br, the upper surface 12A of the holding portion 120 which is provided with a plurality of irregularities 12Ar, and the lower surface 12B of the holding portion 120 which is provided with a plurality of irregularities 12Br. The second lead electrode 15b is provided across the lower surface 11B of the peripheral portion 118 which has a plurality of bumps 18Br, the upper surface 13A of the support arm 130 which has a plurality of bumps 13Ar, the lower surface 13B of the support arm 130 which has a plurality of bumps 13Br, the upper surface 12A of the holding portion 120 which has a plurality of bumps 12Ar, and the lower surface 12B of the holding portion 120 which has a plurality of bumps 12Br. The first connecting electrode 16a and the second connecting electrode 16b are provided on the lower surface 12B of the holding portion 120 which has a plurality of bumps 12Br.

[0109] According to this, by providing multiple irregularities 13Ar, 13Br, 12Ar, and 12Br, the surface structure of the upper surface 11A and lower surface 11B of the peripheral portion 118, the upper surface 13A and lower surface 13B of the support arm 130, and the upper surface 12A and lower surface 12B of the holding portion 120 becomes more complex and the surface area increases, thereby improving the adhesion strength of the first extraction electrode 15a, the second extraction electrode 15b, the first connecting electrode 16a, and the second connecting electrode 16b to the quartz substrate 11. Therefore, damage due to electrode peeling of the quartz oscillator 10 can be suppressed and the reliability of the quartz oscillator 1 can be improved.

[0110] Other embodiments are described below. Components identical or similar to those shown in the first embodiment are denoted by the same or similar reference numerals, and their descriptions are omitted as appropriate. Furthermore, similar effects and benefits from similar components are not mentioned sequentially.

[0111] <Second Embodiment> Next, the configuration of the vibrating section 210 according to the second embodiment will be described with reference to Figure 11. Figure 11 is a cross-sectional view of the vibrating section 210 according to the second embodiment.

[0112] A functional member 260 is attached to the upper surface 11A of the peripheral portion 218. The functional member 260 is, for example, a thermistor or an IC. The multiple irregularities 28Ar provided on the upper surface 11A of the peripheral portion 218 of the vibrating portion 210 are larger than the multiple irregularities 17Ar provided on the upper surface 11A of the central portion 117.

[0113] The maximum dimension T28Ar in the thickness direction of the multiple irregularities 28Ar is greater than both the maximum dimension T17Ar in the thickness direction of the multiple irregularities 17Ar and the maximum dimension T17Br in the thickness direction of the multiple irregularities 17Br (T17Ar < T28Ar, T17Br < T28Ar). Since T17Br < T17Ar, the relationship T17Br < T17Ar < T28Ar holds. Also, since T17Br ≈ T18Br, the relationship T18Br < T28Ar holds.

[0114] The maximum dimension W28Ar in the in-plane direction of the multiple bumps 28Ar is greater than both the maximum dimension W17Ar in the in-plane direction of the multiple bumps 17Ar and the maximum dimension W17Br in the in-plane direction of the multiple bumps 17Br (W17Ar < W28Ar, W17Br < W28Ar). Since W17Br < W17Ar, the relationship W17Br < W17Ar < W28Ar holds. Also, since W17Br ≈ W18Br, the relationship W18Br < W28Ar holds.

[0115] The number density N28Ar of multiple bumps 28Ar is approximately equal to the number density N17Ar of multiple bumps 17Ar (N28Ar ≈ N17Ar). The number density N28Ar of multiple bumps 28Ar is approximately equal to the number density N17Br of multiple bumps 17Br (N28Ar ≈ N17Br), and the number density N18Br of multiple bumps 18Br is approximately equal to N28Ar ≈ N18Br.

[0116] According to this embodiment, the surface structure of the upper surface of the peripheral portion 218 on which the functional member 260 is provided becomes more complex and the surface area increases due to the provision of multiple irregularities 28Ar. Therefore, the adhesion strength of the functional member 260 to the crystal substrate 211 can be improved compared to the case where the functional member is provided on a flat surface. Furthermore, since the multiple irregularities 28Ar are larger than the multiple irregularities 17Ar, the adhesion strength of the functional member 260 to the crystal substrate 211 can be further improved.

[0117] The maximum dimension T28Ar of the multiple protrusions 28Ar only needs to be larger than at least one of the maximum dimension T17Ar of the multiple protrusions 17Ar and the maximum dimension T17Br of the multiple protrusions 17Br. For example, the relationship T17Br < T28Ar ≤ T17Ar may hold. Similarly, the maximum dimension W28Ar only needs to be larger than at least one of the maximum dimensions W17Ar and W17Br, for example, the relationship W17Br < W28Ar ≤ W17Ar may hold. Also, the maximum dimension T28Ar only needs to be equal to or larger than the larger of the maximum dimensions T17Br and T17Ar. If the relationship T17Br < T17Ar ≤ T28Ar, or T17Ar < T17Br ≤ T28Ar holds, the effect of this embodiment, which further improves the adhesion strength of the functional member 260 to the crystal substrate 211, can be obtained.

[0118] <Third Embodiment> Next, the configuration of the quartz crystal oscillator 3 according to the third embodiment will be described with reference to Figure 12. Figure 12 is a cross-sectional view of the quartz crystal oscillator 3 according to the third embodiment.

[0119] The quartz crystal oscillator 300 and the lower cover 20 are metal-bonded, and the quartz crystal oscillator 300 and the upper cover 30 are metal-bonded. The lower joint 340 and the upper joint 350 are made of a metal material containing gold (Au). The plurality of protrusions 32Ar provided on the upper surface 32A of the holding portion 320 are smaller than the plurality of protrusions 17Ar provided on the upper surface 11A of the central portion 117 of the vibrating portion 110, and are smaller than the plurality of protrusions 17Br provided on the lower surface 11B of the central portion 117 of the vibrating portion 110.

[0120] The maximum dimension T32Ar in the thickness direction of the multiple irregularities 32Ar is smaller than both the maximum dimension T17Ar in the thickness direction of the multiple irregularities 17Ar and the maximum dimension T17Br in the thickness direction of the multiple irregularities 17Br (T32Ar < T17Ar, T32Ar < T17Br). The maximum dimension W32Ar in the in-plane direction of the multiple irregularities 32Ar is smaller than both the maximum dimension W17Ar in the in-plane direction of the multiple irregularities 17Ar and the maximum dimension W17Br in the in-plane direction of the multiple irregularities 17Br (W32Ar < W17Ar, W32Ar < W17Br).

[0121] Similarly, the multiple bumps 32Br provided on the lower surface 32B of the holding portion 320 are smaller than the multiple bumps 11Ar provided on the upper surface 11A of the vibrating portion 110, and are also smaller than the multiple bumps 11Br provided on the lower surface 11B of the vibrating portion 110.

[0122] According to this embodiment, the surface structure of the upper surface 32A is made more complex by the multiple irregularities 32Ar, and the surface area of ​​the upper surface 32A is increased, thereby improving the adhesion strength between the holding portion 320 and the upper joint portion 350. Furthermore, since the multiple irregularities 32Ar are smaller than the multiple irregularities 17Ar, 17Br, even the upper joint portion 350 of the metal joint, which is thinner than that of the resin joint, is less likely to be penetrated by the multiple irregularities 32Ar. Therefore, it is possible to suppress the decrease in adhesion strength between the holding portion 320 and the upper lid 30 caused by the multiple irregularities 32Ar contacting the upper lid 30 without going through the upper joint portion 350. Similarly, it is possible to improve the adhesion strength between the holding portion 320 and the lower joint portion 340, and to suppress the decrease in adhesion strength between the holding portion 320 and the lower lid 20.

[0123] Preferably, the multiple irregularities 32Ar are smaller than both the multiple irregularities 17Ar on the upper surface 11A of the peripheral portion 118 and the multiple irregularities 17Br on the lower surface 11B of the peripheral portion 118, and preferably, the multiple irregularities 32Br are smaller than both the multiple irregularities 17Ar and the multiple irregularities 17Br. Preferably, the multiple irregularities 32Ar are smaller than both the multiple irregularities 13Ar on the upper surface 13A of the support arm 130 and the multiple irregularities 13Br on the lower surface 13B of the support arm 130, and preferably, the multiple irregularities 32Br are smaller than both the multiple irregularities 13Ar and the multiple irregularities 13Br. Preferably, the multiple irregularities 32Ar are the smallest among all the irregularities provided on the upper cover 30 side of the quartz oscillator 300, and preferably, the multiple irregularities 32Br are the smallest among all the irregularities provided on the lower cover 20 side of the quartz oscillator 300. Multiple protrusions 32Ar, 32Br may be omitted, and the upper surface 12A and lower surface 12B may be provided in a flat shape. When the upper surface 12A of the holding portion 320 is flat, the decrease in the adhesion strength between the holding portion and the top lid can be further suppressed. The same applies when the lower surface 12B of the holding portion 320 is flat.

[0124] <Fourth Embodiment> Next, the configuration of the quartz crystal oscillator 4 according to the fourth embodiment will be described with reference to Figure 13. Figure 13 is a cross-sectional view of the quartz crystal oscillator 4 according to the fourth embodiment.

[0125] Multiple bumps 42Ar are provided on the upper surface 421A of the crystal substrate 421 in the lower cover 420. These bumps 42Ar are provided over substantially the entire surface of the upper surface 421A, that is, over the region facing the vibrating part 110 of the crystal oscillator 10, the region facing the holding part 120, and the region facing the support arm 130. Of the multiple bumps 42Ar, the size of the bumps in the region facing the vibrating part 110, the size of the bumps in the region facing the holding part 120, and the size of the bumps in the region facing the support arm 130 are substantially equal to each other. In other words, the maximum dimensions in the thickness direction and the maximum dimensions in the in-plane direction are substantially equal to each other. Similarly, multiple bumps 43Br are provided on the lower surface 431B of the crystal substrate 431 in the upper cover 430.

[0126] According to this, the surface structure of the upper surface 421A of the lower cover 420 becomes more complex and the surface area increases as a result of the multiple protrusions 42Ar being provided, thereby improving the adhesion strength of the lower joint 40 to the lower cover 420. Therefore, the adhesion strength between the quartz oscillator 10 and the lower cover 420 can be improved. Similarly, the adhesion strength of the upper joint 50 to the upper cover 430 is improved as a result of the multiple protrusions 43Br being provided, thereby improving the adhesion strength between the quartz oscillator 10 and the upper cover 430.

[0127] When the lower joint is made of resin, it is desirable that the size of the multiple protrusions 42Ar on the lower cover 420 be larger than at least one of the multiple protrusions provided on the upper surface of the central part of the vibrating section of the quartz crystal oscillator, and the multiple protrusions provided on the lower surface of the central part of the vibrating section of the quartz crystal oscillator, and it is desirable that it be larger than both of them. When the lower joint is made of metal, it is desirable that the size of the multiple protrusions 42Ar on the lower cover 420 be smaller than at least one of the multiple protrusions provided on the upper surface of the central part of the vibrating section of the quartz crystal oscillator, and it is desirable that it be smaller than both of them. The same applies to the size of the multiple protrusions 43Br on the upper cover 430.

[0128] Furthermore, the multiple protrusions 42Ar on the lower cover 420 only need to be provided in the region facing the holding portion of the quartz crystal oscillator, and may be omitted in the region facing the vibrating portion and support arm of the quartz crystal oscillator. Also, among the multiple protrusions 42Ar on the lower cover 420, the multiple protrusions provided in the region facing the holding portion of the quartz crystal oscillator may be larger than the multiple protrusions provided in the region facing the vibrating portion of the quartz crystal oscillator. The same applies to the multiple protrusions 43Br on the upper cover 430.

[0129] <Fifth Embodiment> Next, the configuration of the quartz oscillator 500 according to the fifth embodiment will be described with reference to Figures 14 and 15. Figure 14 is a plan view of the quartz oscillator 500 according to the fifth embodiment. Figure 15 is a diagram illustrating the manufacturing method of the quartz oscillator 500 according to the fifth embodiment.

[0130] As shown in Figure 14, when viewed from the positive Y'' axis, the longer side of the quartz oscillator 500 extends in the direction of the X'' axis, which is tilted counterclockwise from the X' axis by an angle ω, and the shorter side of the quartz oscillator 500 extends in the direction of the Z'' axis, which is tilted counterclockwise from the Z' axis by an angle ω. This is because, as shown in Figure 15, when the quartz oscillator 500 is separated from the quartz XT2, the dicing line DL1 is set so that the angle between the dicing line DL1 and the Z' axis is ω, and the dicing line DL2 is set so that the angle between the dicing line DL2 and the X' axis is ω. Specifically, when setting the dicing line DL1 on the quartz XT2, the dicing line DL1 is set in a direction parallel to the Z'' axis, which is the axis obtained by rotating the Z' axis by an angle ω with the Y'' axis as the axis of rotation. Furthermore, when setting the dicing line DL2 on the crystal XT2, the dicing line DL2 is set in a direction parallel to the X'' axis, which is the axis obtained by rotating the X' axis by a rotation angle ω with the Y'' axis as the axis of rotation. Note that when ω = 0, the X'' axis and Z'' axis coincide with the X' axis and Z' axis, and the crystal substrate with ω = 0 is the crystal substrate according to the first embodiment.

[0131] When ψ is the angle between the axis obtained by projecting the X-axis along the Y'' axis onto the first principal surface of the quartz substrate and the long side (X'' axis) of the first principal surface of the quartz substrate, the following relationships hold: ψ = α × φ × θ, and α = -0.0165 ± 0.016 (-0.0325 ≤ α ≤ -0.0005) or +0.0165 ± 0.016 (0.0005 ≤ α ≤ 0.0325). Furthermore, it is desirable that at least one of the following relationships holds: 1 degree ≤ φ ≤ 14 degrees, and 30 degrees ≤ θ ≤ 40 degrees, and it is even more desirable that both of these relationships hold.

[0132] According to this, the relationship α = -0.0165 ± 0.016 or α = +0.0165 ± 0.016 holds, making it possible to provide a quartz oscillator 500 that has good frequency-temperature characteristics and can suppress the generation of sub-vibrations.

[0133] <Sixth Embodiment> Next, the configuration of the crystal oscillator 6 according to the sixth embodiment will be described with reference to Figure 16. Figure 16 is a cross-sectional view of the crystal oscillator 6 according to the sixth embodiment.

[0134] The quartz oscillator 6 comprises a quartz oscillator 602, a lid member 640, a base member 650, and a joint 690. The quartz oscillator 602 is provided between the base member 650 and the lid member 640. The base member 650 and the lid member 640 constitute a retainer for housing the quartz oscillator 602. The base member 650 is flat, and the lid member 640 is concave, having a cavity that opens on the side facing the base member 650. The quartz oscillator 602 is housed in the cavity of the lid member 640. However, the shapes of the base member 650 and the lid member 640 are not limited to the above, as long as at least the excited portion of the quartz oscillator 602 is housed in the retainer. For example, the lid member may be flat, and the base member 650 may be concave, having a cavity that opens on the side facing the lid member 640. Both the base member 650 and the lid member 640 may be provided in a concave shape with cavities that open to each other.

[0135] The quartz oscillator 602 comprises a quartz substrate 610, a first excitation electrode 620, a second excitation electrode 630 facing the first excitation electrode 620, and a first connecting electrode 624 that electrically connects the first excitation electrode 620 to the base member 650. The quartz substrate 610 is a flat quartz crystal with a uniform thickness and has a rectangular upper surface 612 and a lower surface 614 facing each other. The long sides of the upper surface 612 and the lower surface 614 extend in the X'' axis direction, and the short sides of the upper surface 612 and the lower surface 614 extend in the ZX'' axis direction.

[0136] The first excitation electrode 620 is provided on the upper surface 612 of the quartz substrate 610, and the second excitation electrode 630 is provided on the lower surface 614 of the quartz substrate 610. The first connecting electrode 624 is provided at the corner of the lower surface 614 of the quartz substrate 610. The first excitation electrode 620 and the first connecting electrode 624 are electrically connected by a first extraction electrode provided from the upper surface 612 to the lower surface 614 of the quartz substrate 610.

[0137] Although not shown in the figures, the quartz oscillator 602 further includes a second connecting electrode that electrically connects the second excitation electrode 630 to the base member 650, and a second extraction electrode that electrically connects the second excitation electrode 630 and the second connecting electrode. The second extraction electrode is provided on the lower surface 614 of the quartz substrate 610. The second connecting electrode is provided at the corner of the lower surface 614 of the quartz substrate 610. The first connecting electrode 624 and the second connecting electrode are provided side by side along the Z'' axis.

[0138] The base member 650 is equipped with a quartz crystal oscillator 602. The base member 650 comprises a substrate 651, a first electrode pad 660, and a first conductive holding member 680.

[0139] The substrate 651 is a plate-shaped insulator having an upper surface 652 and a lower surface 654 that face each other in the thickness direction. The upper surface 652 is located on the side facing the quartz oscillator 602 and the lid member 640, and corresponds to the mounting surface on which the quartz oscillator 602 is mounted. From the viewpoint of suppressing thermal stress acting from the substrate 651 to the quartz oscillator 602 due to thermal history such as reflow soldering, it is preferable that the substrate 651 be made of a heat-resistant material. From a similar viewpoint, the substrate 651 may be made of a material having a coefficient of thermal expansion close to that of the quartz substrate 610. The substrate 651 may be made of, for example, a ceramic substrate, a glass substrate, or a quartz substrate.

[0140] The first electrode pad 660 is electrically connected to the first connecting electrode 624 of the quartz crystal oscillator 602. The first conductive holding member 680 electrically connects the base member 650 and the quartz crystal oscillator 602, and also holds the quartz crystal oscillator 602 in an excitable manner. The first conductive holding member 180 electrically connects the first connecting electrode 624 of the quartz crystal oscillator 602 and the first electrode pad 660 of the base member 650. The first conductive holding member 680 is a cured product of a conductive adhesive containing a thermosetting resin or a photocurable resin. The main component of the first conductive holding member 680 is, for example, silicone resin. The first conductive holding member 680 contains conductive particles, and for example, metal particles containing silver (Ag) are used as the conductive particles.

[0141] The main component of the first conductive retaining member 680 is not limited to silicone resin, but may be epoxy resin, acrylic resin, or the like. Furthermore, the conductive particles contained in the first conductive retaining member 680 are not limited to silver particles, but may be formed from other metals, conductive ceramics, conductive organic materials, etc. The first conductive retaining member 680 may also contain a conductive polymer.

[0142] Although not shown in the figures, the base member 650 further includes a second electrode pad electrically connected to the second connecting electrode of the quartz crystal oscillator 602, and a second conductive retaining member electrically connecting the second connecting electrode of the quartz crystal oscillator 602 and the second electrode pad of the base member 650. The first electrode pad 660 and the second electrode pad are arranged side by side along the Z'' axis, and the same applies to the first conductive retaining member 680 and the second conductive retaining member.

[0143] The lid member 640 has a top wall portion 641 and a side wall portion 642 extending from the outer edge of the top wall portion 641 toward the base member 650. The top wall portion 641 faces the base member 650 with the quartz crystal oscillator 602 in between, and the side wall portion 642 surrounds the quartz crystal oscillator 602 with a gap between them. The material of the lid member 640 is preferably a conductive material, and more preferably a highly airtight metallic material. By making the lid member 640 out of a conductive material, an electromagnetic shielding function is provided to the lid member 640 that reduces the inflow and outflow of electromagnetic waves into and out of the internal space 601. From the viewpoint of suppressing the generation of thermal stress, the material of the lid member 640 is preferably a material that has a coefficient of thermal expansion close to that of the base member 650, for example, an Fe-Ni-Co alloy whose coefficient of thermal expansion near room temperature matches that of glass or ceramic over a wide temperature range. The lid member 640 is grounded by an external electrode (not shown).

[0144] The joint 690 joins the base member 650 and the lid member 640, sealing the internal space 601 in which the quartz oscillator 602 is housed. The joint 690 is provided in a frame shape around the entire circumference of the outer edge of the base member 650 and is sandwiched between the tip of the side wall portion 642 of the lid member 640 and the upper surface 652 of the base member 650. The joint 690 is provided by an insulating material. The joint 690 is provided by an organic adhesive, for example, an epoxy, vinyl, acrylic, urethane, or silicone resin. The material of the joint 690 is not limited to organic adhesives, and may also be an inorganic adhesive, such as a silicon-based adhesive containing water glass or a calcium-based adhesive containing cement. The material of the joint 690 may also be low-melting-point glass (for example, lead borate or tin phosphate). The material of the joint 690 may also be a metal material.

[0145] In the quartz oscillator 602, a plurality of irregularities 67Ar are provided on the upper surface 612 of the quartz substrate 610 in the region overlapping with the first excitation electrode 620, and a plurality of irregularities 67Br are provided on the lower surface 614 of the quartz substrate 610 in the region overlapping with the second excitation electrode 630. On the lower surface 614 of the quartz substrate 610, a plurality of irregularities 68Br are provided in the region outside the region overlapping with the second excitation electrode 630 and overlapping with the first connecting electrode 624 and the first conductive holding member 680. Although not shown in the figure, a plurality of irregularities 68Br are also provided on the lower surface 614 of the quartz substrate 610, outside the region overlapping with the second excitation electrode 630 and overlapping with the second connecting electrode and the second conductive holding member.

[0146] The multiple irregularities 68Br are larger than at least one of the multiple irregularities 67Ar and the multiple irregularities 67Br, and preferably larger than both of the multiple irregularities 67Ar and the multiple irregularities 67Br. Specifically, when the maximum dimensions of the multiple irregularities 68Br, 67Ar, and 67Br in the thickness direction are T68Br, T67Ar, and T67Br, the relationship T67Ar < T68Br or T67Br < T68Br holds, and preferably T67Ar < T68Br and T67Br < T68Br holds. The same relationship holds for the maximum dimensions in the in-plane direction.

[0147] According to this, the adhesion strength of the quartz oscillator 602 to the first conductive retaining member 680 and the second conductive retaining member can be improved.

[0148] Furthermore, the multiple irregularities 68Br may be equal in size to or smaller than at least one of the multiple irregularities 67Ar and the multiple irregularities 67Br. For example, the relationship between the maximum dimensions in the thickness direction may be T67Br < T68Br ≤ T67Ar, or T67Ar < T68Br ≤ T67Br. The same applies to the relationship between the maximum dimensions in the in-plane direction.

[0149] In this embodiment as well, when ψ = α × φ × θ, the relationship α = -0.0165 ± 0.016 (-0.0325 ≤ α ≤ -0.0005) or +0.0165 ± 0.016 (0.0005 ≤ α ≤ 0.0325) holds, and the relationship 1 degree ≤ φ ≤ 14 degrees holds, and the relationship 30 degrees ≤ θ ≤ 40 degrees holds.

[0150] Next, the effect of rotation angles φ, θ, and coefficient α on suppressing secondary vibrations will be explained with reference to Figures 17 to 19. Figure 17 is a secondary vibration intensity map in a comparative example of the sixth embodiment. Figure 18 is a secondary vibration intensity map in the first embodiment of the sixth embodiment. Figure 19 is a secondary vibration intensity map in the second embodiment of the sixth embodiment.

[0151] The secondary vibration intensity map of the comparative example shown in Figure 17 is a mapping of the secondary vibration of a quartz crystal oscillator simulated under the conditions φ = 8 degrees, θ = 35.25 degrees, ψ = 0 degrees, and α = 0 onto the main surface of the quartz crystal oscillator. The secondary vibration intensity map of the first embodiment shown in Figure 18 is a mapping of the secondary vibration of a quartz crystal oscillator simulated under the conditions φ = 8 degrees, θ = 35.25 degrees, ψ = 4.637 degrees, and α = 0.0164 onto the main surface of the quartz crystal oscillator. The secondary vibration intensity map of the second embodiment shown in Figure 19 is a mapping of the secondary vibration of a quartz crystal oscillator simulated under the conditions φ = 9 degrees, θ = 35.25 degrees, ψ = 5.223 degrees, and α = 0.0165 onto the main surface of the quartz crystal oscillator. In the secondary vibration maps of Figures 17 to 19, the horizontal axis represents the long side of the quartz crystal oscillator, and the vertical axis represents the short side of the quartz crystal oscillator.

[0152] In the comparative example, φ and θ are within the numerical range of this embodiment, but α is outside the numerical range of this embodiment. The comparative example and the first embodiment share φ and θ, but differ in α. The first embodiment and the second embodiment share θ and α substantially, but differ in φ.

[0153] As shown in Figure 17, in the comparative example of the quartz crystal oscillator, strong secondary vibrations are generated in the central part that excites the main vibration. The region where these secondary vibrations are strong extends in a band shape along the short side of the quartz crystal oscillator, traversing the central part. In contrast, as shown in Figures 18 and 19, in the quartz crystal oscillators of the first and second embodiments, the generation of secondary vibrations in the central part that excites the main vibration is suppressed. Thus, in this embodiment, the generation of secondary vibrations can be suppressed.

[0154] Furthermore, comparing the first and second embodiments, the generation of secondary vibrations in the central region is further suppressed in the first embodiment with φ = 8 degrees than in the second embodiment with φ = 9 degrees. From this, it is desirable that the relationship 1 degree ≤ φ ≤ 8 degrees also holds true in order to suppress secondary vibrations.

[0155] In this specification, a quartz crystal resonator comprising a quartz crystal element is used as an example of a piezoelectric element, but the piezoelectric element is not limited to this. Suitable piezoelectric elements for use in the piezoelectric resonator according to this embodiment include, for example, piezoelectric ceramics such as lead zirconate titanate (PZT) and aluminum nitride, and piezoelectric single crystals such as lithium niobate and lithium tantalate, but are not limited to these and can be appropriately selected.

[0156] The embodiments of the present invention are not particularly limited and can be applied as appropriate to any device that performs electromechanical energy conversion by the piezoelectric effect, such as timing devices, sound generators, oscillators, and load sensors.

[0157] As described above, according to one aspect of the present invention, it is possible to provide a piezoelectric vibration element and a method for manufacturing the same that can improve productivity.

[0158] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified or improved without departing from its spirit, and equivalents thereof are also included. That is, embodiments and / or modifications made by those skilled in the art are also included in the scope of the present invention, as long as they retain the features of the present invention. For example, the elements and their arrangement, materials, conditions, shapes, sizes, etc., of the embodiments and / or modifications are not limited to those exemplified and can be modified as appropriate. Furthermore, the embodiments and modifications are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments and / or modifications is possible, and these are also included in the scope of the present invention as long as they retain the features of the present invention.

[0159] 1...Crystal oscillator 10...Crystal oscillating element 11...Crystal substrate 110...Vibrating part 117...Central part 118...Peripheral part 120...Holding part 130...Support arm 11A...Upper surface of the crystal substrate in the vibrating part 12A...Upper surface of the crystal substrate in the holding part 13A...Upper surface of the crystal substrate in the support arm 11B...Lower surface of the crystal substrate in the vibrating part 12B...Lower surface of the crystal substrate in the holding part 13B...Lower surface of the crystal substrate in the support arm 11Ar, 17Ar, 18Ar...Multiple bumps and grooves provided on the upper surface of the vibrating part 12Ar...Multiple bumps and grooves provided on the upper surface of the holding part 13Ar...Multiple bumps and grooves provided on the upper surface of the support arm 11Br, 17Br, 18Br...Multiple bumps and grooves provided on the lower surface of the vibrating part 12Br...Multiple bumps and grooves provided on the lower surface of the holding part 13Br...Multiple bumps and grooves provided on the lower surface of the support arm 20...Bottom cover 21A... Top surface of the lower cover 21B... Bottom surface of the lower cover 30... Top cover 31A... Top surface of the upper cover 31B... Bottom surface of the upper cover 40... Lower joint 50... Upper joint 14a... First excitation electrode 14b... Second excitation electrode 15a... First extraction electrode 15b... Second extraction electrode 16a... First connecting electrode 16b... Second connecting electrode

Claims

1. A piezoelectric vibrating element comprising: a piezoelectric substrate having a first main surface and a second main surface facing each other; a first excitation electrode provided on the first main surface of the piezoelectric substrate; and a second excitation electrode provided on the second main surface of the piezoelectric substrate, wherein a plurality of first irregularities are provided in the region of the first main surface of the piezoelectric substrate that overlaps with the first excitation electrode; and a plurality of second irregularities are provided in the region of the second main surface of the piezoelectric substrate that overlaps with the second excitation electrode; and the first maximum dimension of the plurality of first irregularities in the thickness direction of the piezoelectric substrate is different from the second maximum dimension of the plurality of second irregularities in the thickness direction.

2. The piezoelectric vibration element according to claim 1, wherein the first maximum dimension is at least twice the second maximum dimension.

3. A plurality of third irregularities are provided on the outer side of the region of the first main surface of the piezoelectric substrate that overlaps with the first excitation electrode, a functional member is bonded to the region where the plurality of third irregularities are provided, the third maximum dimension of the plurality of third irregularities in the thickness direction is equal to or greater than the first maximum dimension, and the first maximum dimension is greater than the second maximum dimension, the piezoelectric vibration element according to claim 1 or 2.

4. The piezoelectric vibrating element according to any one of claims 1 to 3, wherein the piezoelectric substrate is a quartz substrate.

5. With respect to the X, Y, and Z axes which are the crystal axes of a quartz crystal, the axes obtained by rotating the X and Y axes with a rotation angle φ around the Z axis are defined as the X' axis and Y' axis, respectively, and the axes obtained by rotating the Y' axis and Z axis with a rotation angle θ around the X' axis are defined as the Y'' axis and Z' axis, respectively, the first principal surface and the second principal surface are perpendicular to the Y'' axis, the piezoelectric vibration element according to claim 4.

6. The piezoelectric vibrating element according to any one of claims 1 to 5, wherein the first maximum dimension and the second maximum dimension are 0.01 μm or more and 1 μm or less.

7. A piezoelectric vibrator comprising: a piezoelectric vibrator according to any one of claims 1 to 6; a first substrate provided facing the piezoelectric vibrator; a second substrate provided on the opposite side from the first substrate and facing the piezoelectric vibrator; a first joint for joining the piezoelectric vibrator and the first substrate; and a second joint for joining the piezoelectric vibrator and the second substrate, wherein the first joint is made of resin or low-melting-point glass; a plurality of fourth irregularities are provided in the region of the first main surface of the piezoelectric substrate that overlaps with the first joint; the fourth maximum dimension of the plurality of fourth irregularities in the thickness direction is greater than the second maximum dimension; and the first maximum dimension is greater than the second maximum dimension.

8. A piezoelectric vibrator comprising: a piezoelectric vibrating element according to any one of claims 1 to 6; a first substrate provided facing the piezoelectric vibrating element; a second substrate provided on the opposite side from the first substrate and facing the piezoelectric vibrating element; a first joint for joining the piezoelectric vibrating element and the first substrate; and a second joint for joining the piezoelectric vibrating element and the second substrate, wherein the first joint is made of metal; a plurality of fifth irregularities are provided in the region of the first main surface of the piezoelectric substrate that overlaps with the first joint; and the fifth maximum dimension of the plurality of fifth irregularities in the thickness direction is smaller than both the first maximum dimension and the second maximum dimension.

9. A piezoelectric vibrator comprising: a piezoelectric vibrator according to any one of claims 1 to 6; a base member on which the piezoelectric vibrator is mounted; a lid member for housing the piezoelectric vibrator between itself and the base member; a joint for joining the base member and the lid member; and a conductive holding member for electrically connecting and holding the piezoelectric vibrator to the base member, wherein the conductive holding member is made of a resin material, a plurality of sixth irregularities are provided in the region of the second main surface of the piezoelectric substrate that overlaps with the conductive holding member, and the sixth maximum dimension of the plurality of sixth irregularities in the thickness direction is greater than at least one of the first maximum dimension and the second maximum dimension.

10. The piezoelectric substrate is a quartz substrate, and with respect to the X, Y, and Z axes which are the crystal axes of the quartz, the axes obtained by rotating the X and Y axes with a rotation angle φ around the Z axis are defined as the X' axis and Y' axis, respectively, and the axes obtained by rotating the Y' axis and Z axis with a rotation angle θ around the X' axis are defined as the Y'' axis and Z' axis, respectively, the first principal surface and the second principal surface are perpendicular to the Y'' axis, the first principal surface is rectangular, and the angle between the axis obtained by projecting the X axis along the Y'' axis onto the first principal surface and the long side of the first principal surface is ψ, and when ψ = α × φ × θ, the following holds: -0.0325 ≤ α ≤ -0.0005 or 0.0005 ≤ α ≤ 0.0325, the piezoelectric vibrator according to claim 9.

11. The piezoelectric vibrator according to claim 10, wherein, when viewed from the positive direction side of the Z-axis and counterclockwise is considered positive, the relationship 1 degree ≤ φ ≤ 14 degrees holds.

12. The piezoelectric vibrator according to claim 10 or 11, wherein, when viewed from the positive direction side of the X' axis and counterclockwise is considered positive, the relationship 30° ≤ θ ≤ 40° holds.

13. The method includes: preparing a quartz crystal having X, Y, and Z axes as crystal axes; identifying the X' and Y' axes by rotating the X and Y axes by a rotation angle φ with the Z axis as the axis of rotation; cutting the quartz crystal with a plane perpendicular to the X' axis; identifying the Y'' and Z' axes by rotating the Y' and Z axes by a rotation angle θ with the X' axis as the axis of rotation; cutting the quartz crystal with a cutting plane perpendicular to the Y'' axis; polishing the cutting plane to form a polished surface; etching the polished surface to form a first main surface and a second main surface of a quartz substrate; providing a first excitation electrode on the first main surface of the quartz substrate; and providing a second excitation electrode on the second main surface of the quartz substrate, wherein a plurality of first irregularities are provided in the region of the first main surface of the quartz substrate that overlaps with the first excitation electrode. A method for manufacturing a piezoelectric vibration element, wherein a plurality of second irregularities are provided in the region of the second main surface of the quartz substrate that overlaps with the second excitation electrode, and the first maximum dimension of the plurality of first irregularities in the thickness direction of the quartz substrate is different from the second maximum dimension of the plurality of second irregularities in the thickness direction.

14. The method for manufacturing a piezoelectric vibration element according to claim 13, wherein the etching process involves wet etching the entire surface of the region where the first excitation electrode is provided and the region where the second excitation electrode is provided, and the plurality of first and second irregularities are formed by the etching process.

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