Piezoelectric element, piezoelectric device and piezoelectric wafer

Abstract

This piezoelectric body has a first part, a second part and a third part. In a plan view, at least a portion of the second part is located on one side of a first direction relative to the first part. At least a portion of the third part is located between the first part and the second part in the first direction. The second part is thicker at least on a first side of the thickness direction relative to the first part. An excitation electrode is located on the first part. A lead electrode is led from the excitation electrode. A connection electrode is connected to the lead electrode and located on the second part. In a cross-section along the first direction and along the thickness direction, the first surface of the third part which faces the first side has a peak at a position that is remote from the first part and from the second part.

Description

[Technical field]

[0001] The present disclosure relates to a piezoelectric element, a piezoelectric device having the piezoelectric element, and a piezoelectric wafer from which a large number of the piezoelectric elements are obtained. [Background technology]

[0002] 2. Description of the Related Art Piezoelectric devices such as quartz crystal resonators and quartz crystal oscillators are known (see, for example, the following patent documents). Such piezoelectric devices include a piezoelectric element such as a quartz crystal element, and a package that holds the piezoelectric element.

[0003] A piezoelectric element, for example, has a piezoelectric plate (a plate-shaped piezoelectric body) and two excitation electrodes overlapping the front and back of the piezoelectric plate. The piezoelectric plate vibrates when a voltage is applied to the piezoelectric plate by the two excitation electrodes. This vibration is used, for example, to generate an oscillation signal (for example, a signal whose signal strength oscillates at a certain frequency).

[0004] The piezoelectric element also has two extraction electrodes drawn from the two excitation electrodes toward one end of the piezoelectric plate (e.g., one short side of a rectangular piezoelectric plate), and two connection electrodes located at one end of the piezoelectric plate and connected to the two extraction electrodes. The two connection electrodes are bonded to two pads on the package, for example, by a conductive bonding material. This electrically connects the piezoelectric element to the package and supports it.

[0005] Regarding the above-mentioned piezoelectric element, a piezoelectric plate having a plurality of portions (regions) with different thicknesses is known. For example, the piezoelectric plate of Patent Document 1 has a vibration portion, a fixed portion that is thicker than the vibration portion, and an intermediate portion that is located between the vibration portion and the fixed portion and that gradually becomes thicker from the vibration portion side to the fixed portion side. Two excitation electrodes are located on the front and back of the vibration portion. Two connection electrodes are located on the fixed portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-34061 A Summary of the Invention

[0007] A piezoelectric element according to an embodiment of the present disclosure includes a piezoelectric body, an excitation electrode, an extraction electrode, and a connection electrode. The piezoelectric body includes a first portion, a second portion, and a third portion in a plan view. In a plan view, at least a portion of the second portion is located on one side of the first portion in a first direction. At least a portion of the third portion is located between the first portion and the second portion in the first direction. The second portion is thicker than the first portion toward at least a first side in a thickness direction. The excitation electrode is located in the first portion. The extraction electrode is extracted from the excitation electrode. The connection electrode is connected to the extraction electrode and is located in the second portion. In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side has a peak at a position away from the first portion and the second portion.

[0008] A piezoelectric element according to an embodiment of the present disclosure includes a piezoelectric body, an excitation electrode, an extraction electrode, and a connection electrode. The piezoelectric body includes a first portion, a second portion, and a third portion in a plan view. In a plan view, at least a portion of the second portion is located on one side of the first direction with respect to the first portion. At least a portion of the third portion is located between the first portion and the second portion in the first direction. The first portion is thicker at least toward a first side in a thickness direction with respect to the second portion. The excitation electrode is located in the first portion. The extraction electrode is extracted from the excitation electrode. The connection electrode is connected to the extraction electrode and is located in the second portion. In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side has a peak and a recess. The peak is away from the first portion and the second portion. The recess is located on the first portion side of the peak and has a portion located on the opposite side from the first side relative to the peak in the thickness direction.

[0009] A piezoelectric device according to one aspect of the present disclosure includes any one of the piezoelectric elements described above and a package in which the piezoelectric element is mounted.

[0010] A piezoelectric wafer according to an embodiment of the present disclosure has an inner periphery, an outer periphery, and an intermediate portion. The inner periphery has a plurality of regions constituting a plurality of piezoelectric elements. The outer periphery has a portion located on one side of the inner periphery in a first direction in a plan view. The intermediate portion has a portion located between the outer periphery and the inner periphery in the first direction. The outer periphery is thicker at least toward a first side in a thickness direction than the inner periphery. In a first cross section along the first direction and the thickness direction, a first surface of the intermediate portion facing the first side has a peak at a position away from the outer periphery and the inner periphery. The peak is located between the position of the first side surface of the inner periphery and the position of the first side surface of the outer periphery in the thickness direction. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing a quartz crystal element according to a first embodiment. [Diagram 2] FIG. 2 is a plan view showing region II in FIG. [Diagram 3] 3 is a schematic diagram showing the surface shape of the quartz crystal plate in region III of FIG. 2. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a portion of FIG. 3. [Diagram 5] 2 is a cross-sectional view of a quartz crystal device having the quartz crystal element of FIG. 1. [Figure 6] 2A to 2C are schematic diagrams illustrating a method for manufacturing the quartz crystal element of FIG. 1. [Figure 7] 2A to 2C are cross-sectional views illustrating a method for manufacturing the quartz crystal element of FIG. [Figure 8] Schematic diagrams showing other examples of the surface shape of the third portion of the quartz crystal element. [Figure 9A] 11A to 11C are cross-sectional views showing other examples of the surface shape of the third portion. [Figure 9B] 11A to 11C are cross-sectional views showing other examples of the surface shape of the third portion. [Figure 9C] 10A to 10C are cross-sectional views showing other examples of the surface shape of the third portion. [Figure 10A] FIG. 11 is a plan view showing another example of the position of the third portion. [Figure 10B] FIG. 11 is a plan view showing another example of the position of the third portion. [Figure 11A] FIG. 11 is a plan view showing another example of the position of the third portion. [Figure 11B] FIG. 11 is a plan view showing another example of the position of the third portion. [Figure 12] 10A to 10C are cross-sectional views showing other examples of the thickness of the third portion. [Figure 13] FIG. 11 is a perspective view showing a quartz crystal element according to a second embodiment. [Figure 14] 14 is a schematic diagram showing the surface shape of the quartz crystal plate in region XIV of FIG. 13 . [Figure 15] FIG. 11 is a perspective view showing a wafer according to a third embodiment. [Figure 16] 16 is a schematic diagram showing the surface shape of the wafer in FIG. 15. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic. Therefore, for example, the dimensional ratios in the drawings do not necessarily match the actual ones. The dimensional ratios of the same members in the drawings do not necessarily match. In addition, illustration of details may be omitted, and some shapes may be illustrated in an exaggerated manner. However, the above does not deny that the actual dimensional ratios may be as shown in the drawings, and that features such as shapes and dimensional ratios may be extracted from the drawings.

[0013] For convenience, the drawings may include a Cartesian coordinate system D1-D2-D3. In the piezoelectric element and piezoelectric device according to the embodiment, any direction may be vertical or horizontal. However, for convenience, the +D3 side may be expressed as upward. Furthermore, a plan view or plan perspective view refers to a view parallel to the D3 direction unless otherwise specified. Furthermore, to facilitate understanding of the drawings, the surfaces (i.e., surfaces that are not cross-sectional) of relatively thin layers (e.g., conductor layers) may be hatched.

[0014] In the explanation of the aspects (embodiments and other examples) described relatively later, basically only the differences from the aspects described earlier will be described. Matters that are not specifically mentioned may be considered to be the same as the aspects described earlier or may be inferred from the aspects described earlier. The explanation of the aspects described earlier may be applied to the aspects described later, unless a contradiction or the like arises. In multiple aspects, corresponding components may be given the same symbols for convenience, even if there are differences.

[0015] The term "side" referring to an edge of a planar shape generally refers to an edge of a polygon (in other words, a straight line), but in the description of the embodiments, for convenience, it may be used for an edge of a shape that does not have to be a polygon (for example, an edge that may be curved). Similarly, "long side" and "short side" generally refer to a side of a rectangle, but in the description of the embodiments, for convenience, it may be used for an edge other than a rectangle. "Parallel" usually refers to a relationship in which the distance between straight lines is constant, but in the description of the embodiments, for convenience, it may be used for a relationship in which the distance between lines that do not have to be straight lines (for example, curved lines) is constant.

[0016] When we say "rectangle" or "rectangular shape," unless otherwise specified, it does not have to be a square or a rectangle in the strict sense, and the corners may be chamfered. The same applies to polygons other than rectangles. The chamfering referred to here is larger than the roundness of the corners caused by manufacturing errors (tolerances). It goes without saying that tolerances may exist, and are not limited to chamfering.

[0017] First Embodiment (Overview of quartz crystal elements) FIG. 1 is a perspective view of a crystal element 1 (an example of a piezoelectric element) according to the first embodiment.

[0018] The quartz crystal element 1 has, for example, a configuration with 180° rotational symmetry with respect to a center line (not shown) parallel to the D1 direction. Therefore, the perspective view seen from the -D3 side is the same as that of Fig. 1. However, the quartz crystal element 1 does not have to have a configuration with 180° rotational symmetry.

[0019] The crystal element 1 generates vibrations, for example, when an AC voltage is applied to it. This vibration is used, for example, to generate an oscillation signal whose signal strength (for example, voltage and / or current) oscillates at a certain frequency. In other words, the crystal element 1 is included, for example, in a crystal resonator or a crystal oscillator.

[0020] The quartz crystal element 1 has a quartz crystal plate 3, and a first conductor pattern 5A and a second conductor pattern 5B (hereinafter referred to as "conductor patterns 5" and there may be no distinction between the two) that overlap the quartz crystal plate 3. The two conductor patterns 5 are not short-circuited to each other.

[0021] In plan view, the quartz crystal plate 3 can be considered to have the following three portions: a plate-shaped first portion 13 located on the +D1 side; a second portion 15 located on the -D1 side and thicker than the first portion 13; and a third portion 17 located between the first portion 13 and the second portion 15. The third portion 17 is generally thicker as it approaches the second portion 15.

[0022] Each conductor pattern 5 has an excitation electrode 7, an extraction electrode 9 extracted from the excitation electrode 7, and a connection electrode 11 connected to the extraction electrode 9. That is, the crystal element 1 has a pair of excitation electrodes 7, a pair of extraction electrodes 9, and a pair of connection electrodes 11.

[0023] The pair of excitation electrodes 7 are located at the first portion 13 and contribute to applying a voltage (electric field) to the first portion 13. The pair of connection electrodes 11 are located at the second portion 15 and contribute to mounting the crystal element 1. Specifically, for example, as shown in FIG. 5 described later, the connection electrodes 11 and the package 103 are bonded by a conductive bonding material 105. This electrically connects and fixes the crystal element 1 to the package 103.

[0024] The crystal element 1 may be mounted on a member (for example, a circuit board) other than the package 103. However, for the sake of convenience, the description of the embodiment may be given on the assumption that it is mounted on the package 103.

[0025] When an AC voltage is applied to the pair of connection electrodes 11 via the package 103, the AC voltage is applied to the pair of excitation electrodes 7 via the pair of extraction electrodes 9. As a result, an AC voltage (electric field) is applied to the first portion 13 by the pair of excitation electrodes 7, causing the first portion 13 to vibrate.

[0026] 1, the upper surface 17a (the surface facing the +D3 side) and the lower surface 17b (the surface facing the -D3 side) of the third portion 17 are drawn as flat surfaces for the sake of convenience. However, at least one of the upper surface 17a and the lower surface 17b (hereinafter, the upper surface 17a will be taken as an example) has a shape having a convex portion, as described below.

[0027] Fig. 2 is a plan view showing region II in Fig. 1. Fig. 3 is a schematic diagram showing the surface shape of the quartz crystal plate 3 in region III in Fig. 2.

[0028] In Fig. 3, a plan view of the quartz crystal blank 3 is shown in the center. A cross-sectional view taken along line IIIa-IIIa in the plan view at the center of Fig. 3 is shown on the right side of Fig. 3. A cross-sectional view taken along line IIIb-IIIb in the plan view at the center of Fig. 3 is shown in the upper part of Fig. 3. A cross-sectional view taken along line IIIc-IIIc in the plan view at the center of Fig. 3 is shown in the lower part of the figure. In Fig. 3, the plan view and the cross-sectional view are connected at the same positions by dotted lines.

[0029] As can be seen from the cross-sectional view of Fig. 3, the upper surface 17a of the third region 17 has projections and recesses. In Fig. 2 (plan view) and the plan view of Fig. 3, the peaks PK of the projections 17p and 17s are indicated by solid lines, and the boundaries between the third region 17 and other regions (the first region 13 and the second region 15) are also indicated by solid lines. In the plan view of Fig. 3, the valley lines of the recesses 17r (more specifically, the first recesses 17ra and the second recesses 17rb in the illustrated example) are indicated by dotted lines.

[0030] Fig. 4 is an enlarged cross-sectional view (cross-section parallel to directions D1 and D3) on the right side of Fig. 3. However, in this cross-sectional view, the conductor pattern 5 (first conductor pattern 5A) is also shown.

[0031] The upper surface 17a of the third portion 17 has, for example, at least one convex portion 17p (a first convex portion 17pa and a second convex portion 17pb in the illustrated example), and further has at least one peak PK (a first peak PK1 and a second peak PK2 in the illustrated example). The peak PK is away from the first portion 13 and the second portion 15.

[0032] When at least one peak PK is located between the first portion 13 and the second portion 15 in this way, for example, vibration transmitted from the first portion 13 to the second portion 15 is reduced. The reasons for this include, for example, the following. On the second portion 15 side of the peak PK (the convex portion 17p in another perspective), a space (inside the concave portion 17r) is located, not a part of the crystal plate 3. Therefore, the vibration that has entered the convex portion 17p is not easily transmitted to the second portion 15 side. In addition, since the upper surface 17a of the third portion 17 is not flat, the direction and / or phase of the vibration reflected by the upper surface 17a is likely to differ depending on the position of the upper surface 17a. As a result, the vibration is easily dispersed, and large vibration is unlikely to occur. By reducing the vibration (unintended vibration) transmitted to the second portion 15, for example, the probability of noise occurring in the electrical signal flowing through the connection electrode 11 located at the second portion 15 is reduced. In other words, the characteristics of the crystal element 1 are improved.

[0033] The above is an overview of the quartz crystal element 1 according to the first embodiment. The first embodiment will be described below in the following order: Note that in the following, the D1-D3 cross section refers to a cross section along the D1 direction and the D3 direction (basically parallel), and the D2-D3 cross section refers to a cross section along the D2 direction and the D3 direction (basically parallel). 1. Quartz element 1 (Figs. 1 to 4) 1.1.Crystal base plate 3 1.1.1.First part 13 1.1.2.Second part 15 1.1.3. Third section 17 (excluding surface details) 1.2. Conductor pattern 5 1.2.1.Excitation electrode 7 1.2.2. Connection electrode 11 1.2.3.Extraction electrode 9 1.3. Surface shape of the third part 17 1.3.1. Position, shape and dimensions of each part in plan view 1.3.2. Shape in cross section 1.3.3.Details of the shape in the D1-D3 cross section 1.3.4.Details of the shape in the D2-D3 cross section 2. Example of use of crystal element 1 (Figure 5) 3. Example of manufacturing method of crystal element 1 (FIGS. 6 and 7) 4. Other Examples 4.1. Other Examples of Surface Shape of Third Region (FIGS. 8 to 9(c)) 4.2. Other Examples of the Position of the Third Region (FIGS. 10(a) to 11(b)) 4.3. Other examples of thickness of the second portion (Figure 12) 5. Summary of the First Embodiment

[0034] (1. Quartz crystal element) The crystal element 1 shown in FIG. 1 is, for example, a so-called AT-cut crystal vibration element. That is, the crystal blank 3 is an AT-cut crystal piece. A pair of excitation electrodes 7 overlap both sides of the crystal blank 3 (more specifically, the first portion 13). When a voltage is applied in the thickness direction of the first portion 13 by the pair of excitation electrodes 7, the first portion 13 generates a so-called thickness-shear vibration. The resonance frequency of this vibration (in other words, the oscillation frequency) is basically determined by the thickness of the first portion 13. The crystal element 1 may use a fundamental mode or an overtone mode. In the description of this embodiment, an aspect using the fundamental mode may be taken as an example.

[0035] The crystal element 1 may use vibrations other than thickness shear vibration. Examples of vibrations other than thickness shear vibration include bending vibration mode, torsional vibration mode, length-extensional vibration mode, width-extensional vibration mode, width-length-extensional combined vibration mode, and contour shear vibration mode. In addition, the crystal element 1 using thickness shear vibration may have a cut angle other than AT cut. For example, the crystal element 1 may be of BT cut type. In the description of this embodiment, for convenience, the description and expression may be given on the assumption that the crystal element 1 is of AT cut type, unless otherwise specified.

[0036] The quartz crystal element 1 may be produced by various methods. For example, the quartz crystal blank 3 may be produced by etching (e.g., wet etching). The quartz crystal blank 3 produced by etching may have inclined surfaces (crystal planes from another perspective) on the side surfaces due to the anisotropy of quartz crystal with respect to etching. In the description of the embodiments, the presence of such inclined surfaces may be ignored.

[0037] In the description of dimensions, etc., the description may be applied ignoring the inclined surface as described above, or may be applied taking the inclined surface into consideration, as long as the description does not lack rationality or cause contradictions. For example, when referring to the length in the D1 direction of the quartz crystal plate 3, the length may be the length parallel to the D1 direction from the +D1 side edge of the upper surface (the surface on the +D3 side) of the first portion 13 to the -D1 side edge of the upper surface of the second portion 15, or may be the maximum length in planar perspective (the length including the bulge of the side surface on the -D1 side or the +D1 side).

[0038] (1.1. Crystal base plate) The quartz crystal blank 3 is generally plate-shaped as a whole. The plate-shaped shape is, for example, a shape in which the length (thickness) in a specific direction (D3 direction) is sufficiently shorter than the length in a direction along a plane perpendicular to the specific direction (direction along the D1-D2 plane). The determination of whether or not a part is plate-shaped may be made reasonably based on the thickness and other lengths. The terms front and back of a plate-shaped part basically refer to the widest surface of the plate (the surface on the -D3 side and the surface on the +D3 side), and may be referred to as the main surface in the description of this embodiment.

[0039] As described above, the quartz crystal blank 3 is, for example, an AT-cut quartz crystal piece. That is, when an orthogonal coordinate system XYZ consisting of an X axis (electrical axis), a Y axis (mechanical axis), and a Z axis (optical axis) in the quartz crystal is rotated around the X axis by 30° to 40° (for example, 35°15′) to define an orthogonal coordinate system XY'Z', the quartz crystal blank 3 is a plate having a pair of main surfaces that are basically parallel to the XZ' plane.

[0040] In addition, in the quartz crystal plate 3, for example, the X-axis is parallel to the D1 direction, the Y'-axis is parallel to the D3 direction, and the Z'-axis is parallel to the D2 direction. Thickness-shear vibration is a vibration that moves the +D3 side surface and the -D3 side surface relatively in the D1 direction. The positive side of the D1 direction and the positive side of the X-axis may be on the same side or on opposite sides. The same applies to the relationship between the positive and negative of other directions and the positive and negative of other axes.

[0041] The planar shape of the quartz crystal blank 3 may be set as appropriate. In the illustrated example, the planar shape of the quartz crystal blank 3 is a rectangle having sides parallel to the D1 and D2 directions. Other planar shapes of the quartz crystal blank 3 include, for example, a circle, an ellipse, and a polygon (excluding a rectangle). Also included is a shape in which one or more sides of a polygon (including a rectangle) (for example, one, two, three, or four sides of a rectangle) are curved outward (for example, a circular arc).

[0042] The planar shape of the quartz crystal plate 3 may have either the D1 direction or the D2 direction as its longitudinal direction (in other words, the maximum length in either direction may be longer than the maximum length in the other direction), or such a distinction may not be possible. In the illustrated example, the quartz crystal plate 3 has the D1 direction as its longitudinal direction.

[0043] Various dimensions of the quartz crystal plate 3 may be set appropriately. Examples of dimensional ranges are given below. The length (e.g., maximum length) of the quartz crystal plate 3 in the D1 direction may be 500 μm or more and 1500 μm or less. The length (e.g., maximum length) of the quartz crystal plate 3 in the D2 direction may be 300 μm or more and 800 μm or less. The length (e.g., maximum length) of the first portion 13 in the D1 direction may be 250 μm or more and 1150 μm or less. The thickness of the first portion 13 may be 16 μm or less. This corresponds to a frequency of approximately 100 MHz or more when using the fundamental vibration of thickness shear vibration in an AT-cut plate. The length (e.g., maximum length) of the second portion 15 in the D1 direction may be 100 μm or more and 500 μm or less. The thickness of the second portion 15 may be 50 μm or less.

[0044] (1.1.1. Part 1) The first portion 13 includes, for example, at least the inner region of the quartz crystal plate 3 in a planar view. The inner region here is a region that is away from the outer edge of the quartz crystal plate 3. The first portion 13 may also include, for example, the centroid (center) of the quartz crystal plate 3 in a planar view. To be clear, the centroid is a point at which the first moment of area with respect to any axis passing through that point is zero.

[0045] The shape of the first portion 13 is, for example, plate-like. More specifically, the shape of the first portion 13 is flat. That is, the main surfaces (front and back surfaces; the widest surface of the plate shape) of the first portion 13 are parallel to each other. From another perspective, the thickness of the first portion 13 is constant. The main surface of the first portion 13 is parallel to the D1-D2 plane.

[0046] The planar shape and dimensions of the first portion 13 may be set as appropriate. In the illustrated example, the planar shape of the first portion 13 is rectangular. Each side of the rectangle is parallel to the D1 direction or the D2 direction. Other planar shapes of the first portion 13 include, for example, a circular shape, an elliptical shape, and a polygonal shape (excluding a rectangular shape). Also, a shape in which one or more sides of a polygonal shape (including a rectangular shape) (for example, one, two, three, or four sides of a rectangular shape) are curved (for example, an arc) that bulges outward can be included. In the planar shape of the first portion 13, the D1 direction may be the longitudinal direction, or the D2 direction may be the longitudinal direction, or the length in the D1 direction may be equal to the length in the D2 direction.

[0047] For example, the first portion 13 occupies a relatively large portion of the area (area in plan view) of the quartz crystal plate 3. For example, the first portion 13 occupies more than half the area of ​​the quartz crystal plate 3. However, the first portion 13 may occupy less than half the area of ​​the quartz crystal plate 3.

[0048] (1.1.2.Second part) The second portion 15 includes, for example, at least a portion of the outer peripheral region of the quartz crystal plate 3 in plan view. Also, for example, at least a portion (all of it in the illustrated example) of the second portion 15 is located on one side of the first direction (-D1 side) with respect to the first portion 13 in plan view. In the illustrated example, the first direction is the D1 direction, and from another perspective, it is the direction of thickness shear vibration (X direction). However, the first direction may be a direction other than the direction of thickness shear vibration. Also, the first direction may be the longitudinal direction of the quartz crystal plate 3 (and / or the first portion 13) (in the illustrated example), or may not be.

[0049] The second portion 15 is, for example, flat like the first portion 13. However, the second portion 15 may have a shape that cannot be considered as a plate (a shape in which the thickness in the D3 direction is relatively large compared to the area in the D1-D2 plane). The second portion 15 has surfaces (main surfaces, upper and lower surfaces) parallel to the D1-D2 plane like the first portion 13.

[0050] The planar shape and dimensions of the second portion 15 are arbitrary. In the illustrated example, the planar shape of the second portion 15 is a rectangle having a side parallel to an edge (one side) of the first portion 13 on the second portion 15 side (-D1 side). From another perspective, three edges, namely, the edge of the first portion 13 on the second portion 15 side (-D1 side), the edge of the second portion 15 on the first portion 13 side (+D1 side), and the edge of the second portion 15 on the opposite side to the first portion 13 (-D1 side), are generally parallel. From yet another perspective, the distance between the above three edges in a direction perpendicular to the edge (a tangent in the case of a curved shape) and / or the distance between the above three edges in the D1 direction are constant in the direction in which the edges extend.

[0051] Unlike the illustrated example, the planar shape of the second portion 15 may be a shape other than a rectangle. For example, the four edges (sides) of the second portion 15 may not be straight. The planar shape of the second portion 15 may be a shape that does not include four edges. At least two of the three edges of the edge of the first portion 13 on the second portion 15 side (-D1 side), the edge of the second portion 15 on the first portion 13 side (+D1 side), and the edge of the second portion 15 on the opposite side to the first portion 13 (-D1 side) may have distances between them in a direction perpendicular to the edge (a tangent in the case of a curved shape) and in the D1 direction that change in the direction in which the edges extend.

[0052] The second portion 15 may have a longitudinal direction in the D1 direction or a longitudinal direction in the D2 direction (illustrated example), or the longitudinal direction and the lateral direction may not be distinguished. The length of the second portion 15 in the D1 direction may be shorter (illustrated example), equal to, or longer than the length of the first portion 13 in the D1 direction. The length of the second portion 15 in the D2 direction may be shorter, equal to, or longer than the length of the first portion 13 in the D2 direction (illustrated example).

[0053] As described above, the second portion 15 is thicker than the first portion 13. More specifically, in the illustrated example, the second portion 15 is thicker on both sides in the thickness direction (direction D3) than the first portion 13. The height from the upper surface of the first portion 13 to the upper surface of the second portion 15 (the difference in position in direction D3) and the height from the lower surface of the first portion 13 to the lower surface of the second portion 15 may be the same or different. Furthermore, the above height may be smaller, equal to, or larger than the thickness of the first portion 13.

[0054] (1.1.3. Third Part (excluding details of surface shape)) The third portion 17 extends, for example, over roughly the entire edge of the first portion 13 on the second portion 15 side (-D1 side) and / or the entire edge of the second portion 15 on the first portion 13 side (+D1 side). From another perspective, the length of the third portion 17 in the D2 direction is equal to the length of the first portion 13 in the D2 direction and the length of the second portion 15 in the D2 direction. However, the length of the third portion 17 in the D2 direction may be different from the length of the first portion 13 in the D2 direction and / or the length of the second portion 15 in the D2 direction.

[0055] The third portion 17 is a region connecting the first portion 13 and the second portion 15. Therefore, as can be understood from the above-mentioned explanations regarding the planar shapes of the first portion 13 and the second portion 15, the planar shape of the third portion 17 is arbitrary. In the illustrated example, the planar shape of the third portion 17 is rectangular. The edge of the first portion 13 on the second portion 15 side (-D1 side) and the edge of the second portion 15 on the first portion 13 side (+D1 side) correspond to the edge of the third portion 17 on the first portion 13 side (+D1 side) and the edge of the third portion 17 on the second portion 15 side (-D1 side). Therefore, the above-mentioned explanations regarding the front two edges may be applied to the rear two edges. The edge of the third portion 17 on the -D2 side or +D2 side may be straight (in the illustrated example) or may not be straight. Furthermore, the planar shape of the third portion 17 may be a shape that does not include four edges (sides).

[0056] The third portion 17 may have a longitudinal direction in the D1 direction or a longitudinal direction in the D2 direction (illustrated example), or the longitudinal direction and the lateral direction may not be distinguished. The length of the third portion 17 in the D1 direction may be shorter (illustrated example) than the length of the first portion 13 and / or the second portion 15 in the D1 direction, or may be equal to or longer than the length of the first portion 13 and / or the second portion 15 in the D1 direction.

[0057] The length of the third portion 17 in the direction D1 may be relatively long. For example, the height from the upper surface of the first portion 13 to the upper surface of the second portion 15 is defined as t1 (see FIG. 3). In this case, the length of the third portion 17 in the direction D1 is, for example, t1×tan -1 For example, the length of the third portion 17 in the D1 direction may be 1.5 times or more, 2 times or more, or 3 times or more as long as t1.

[0058] (1.2. Conductive Pattern) The material of the conductive pattern 5 may be, for example, a metal. Examples of the metal include nickel (Ni), chromium (Cr), titanium (Ti), gold (Au), or silver (Ag), or an alloy containing at least one of these as a main component. The conductive pattern 5 may be configured with one metal layer made of a single material, or may be configured by laminating a plurality of metal layers made of different materials. The conductive pattern 5 may have the same material composition over its entire area, or may have different material composition depending on the region. The thickness of the conductive pattern 5 may be, for example, approximately constant over its entire area, or may not be constant.

[0059] (1.2.1. Excitation electrode) As described above, the pair of excitation electrodes 7 are located on both main surfaces of the first portion 13 to apply a voltage to the first portion 13. For example, the pair of excitation electrodes 7 overlap each other almost exactly in a plan view. However, there may be portions that do not overlap each other. The position, shape, size, etc. of each excitation electrode 7 in a plan view are arbitrary.

[0060] For example, in a plan view, the excitation electrode 7 is located in a region on the central side of the first portion 13. From another perspective, the excitation electrode 7 is located away from the outer edge of the first portion 13. The geometric center of the excitation electrode 7, for example, approximately coincides with the geometric center of the first portion 13 in the D2 direction. In addition, the geometric center of the excitation electrode 7 may be located on the +D1 side, may coincide with the geometric center of the first portion 13, or may be located on the -D1 side in the D1 direction. Each excitation electrode 7 may occupy, for example, ⅓ or more of the area of ​​the upper surface or lower surface of the first portion 13.

[0061] Also, for example, the shape of the excitation electrode 7 may be similar to the shape of the first portion 13 (as in the illustrated example), or may be different. An example of the former is a mode in which the shape of the first portion 13 is rectangular, while the shape of the excitation electrode 7 is rectangular having a long side parallel to the long side of the first portion 13 (at least one of the long sides may be square), as in the illustrated example. An example of the latter is a mode in which the shape of the first portion 13 is rectangular, while the shape of the excitation electrode 7 is circular, elliptical, or polygonal (excluding rectangular).

[0062] Regardless of whether the shape of the excitation electrode 7 and the shape of the first portion 13 are similar in plan view or not, the description of the planar shape of the first portion 13 may be applied to the planar shape of the excitation electrode 7, as long as no contradiction occurs. In addition, in a mode in which the excitation electrode 7 and the first portion 13 have shapes that allow the longitudinal direction and the lateral direction to be specified, the longitudinal direction may or may not coincide with the longitudinal direction of the first portion 13.

[0063] (1.2.2. Connection electrodes) Each connection electrode 11 has a portion overlapping at least the lower surface (the surface on the -D3 side) of the second portion 15. Then, as shown in Fig. 5 described later, the portion of the connection electrode 11 overlapping the lower surface of the second portion 15 faces a pad 111 of the package 103 and is bonded to the pad 111 by a bonding material 105.

[0064] In the illustrated example, each connection electrode 11 also has a portion overlapping the upper surface of the second portion 15. This allows, for example, the crystal element 1 to have either of the pair of principal surfaces as the lower surface. Each connection electrode 11 also has a portion that connects the portion overlapping the upper surface of the second portion 15 with the portion overlapping the lower surface of the second portion 15. For example, this portion overlaps the side surface on the -D1 side of the second portion 15, or the portion located on the -D2 side or +D2 side.

[0065] In the illustrated example, the connection electrode 11 extends not only to the second portion 15 but also to the third portion 17 and the first portion 13. Unlike the illustrated example, the connection electrode 11 may be located only at the second portion 15, or only at the second portion 15 and the third portion 17. Also, unlike the description of this embodiment, in the conductor pattern 5 shaped as in the illustrated example, only the portion located at the second portion 15 may be regarded as a connection electrode (the portions located at the first portion 13 and the third portion 17 may be regarded as an extraction electrode).

[0066] The two connection electrodes 11 (at least the portions located on the underside of the second portion 15; the same applies below) are aligned in the D2 direction. More specifically, for example, the two connection electrodes 11 may be provided in positions, shapes, and sizes that are approximately line-symmetrical with respect to a center line (not shown) parallel to the D1 direction of the quartz crystal plate 3. The specific positions, shapes, sizes, etc. of the connection electrodes 11 are arbitrary. In the example shown, the portion of the connection electrode 11 located on the underside (or upper surface) of the second portion 15 has a rectangular shape. The shape of that portion may be a shape other than rectangular.

[0067] (1.2.3. Extraction electrode) The position, shape and dimensions of each extraction electrode 9 may vary as long as it can connect the corresponding excitation electrode 7 and connection electrode 11 to each other. In the illustrated example, the extraction electrode 9 located on the upper surface (+D3 side surface) of the quartz crystal plate 3 connects the excitation electrode 7 located on the upper surface of the quartz crystal plate 3 to the portion of the corresponding connection electrode 11 located on the upper surface of the quartz crystal plate 3. Similarly, the extraction electrode 9 located on the lower surface (-D3 side surface) of the quartz crystal plate 3 connects the excitation electrode 7 located on the lower surface of the quartz crystal plate 3 to the portion of the other corresponding connection electrode 11 located on the lower surface of the quartz crystal plate 3.

[0068] In the illustrated example, the connection electrode 11 extends not only to the second portion 15 but also to the third portion 17 and the first portion 13, so that each extraction electrode 9 overlaps only one of the main surfaces (the surface on the -D3 side or the +D3 side) of the first portion 13. However, as can be understood from the above description of the connection electrode 11, the extraction electrode 9 may overlap the surface on the +D3 side or the -D3 side of the third portion 17, and may further overlap the surface on the +D3 side or the -D3 side of the second portion 15. The extraction electrode 9 may also have a portion overlapping the side surface on the -D2 side or the +D2 side of the quartz crystal plate 3.

[0069] More specifically, the position, shape, size, etc., of the extraction electrode 9 are arbitrary. In the illustrated example, the extraction electrode 9 extends parallel to the direction D1 with a constant width from the end of the edge portion on the second portion 15 side of the excitation electrode 7. Unlike the illustrated example, the extraction electrode 9 may extend from a corner of the excitation electrode 7, extend obliquely in the direction D1, or have a variable width. To be clear, the width of the extraction electrode 9 (the length in the direction perpendicular to the direction in which the extraction electrode 9 extends; in the illustrated example, the length in the direction D2) is narrower than the width of the connection electrode 11 (for example, the length in the direction D2).

[0070] (1.3. Surface shape of the third part) In the description here, of the upper surface 17a (surface on the +D3 side) and the lower surface 17b (surface on the -D3 side) of the third portion 17, the cross-sectional shape of the upper surface 17a will be described. The cross-sectional shape of the lower surface 17b may be the same as that of the upper surface 17a, or may be a different shape (e.g., planar) from that of the upper surface 17a. While the lower surface 17b has the shape of the upper surface 17a described here, the upper surface 17a may have a different shape (e.g., planar) from that described here.

[0071] As shown in Figs. 2 to 4, the top surface 17a of the third portion 17 generally forms an inclined surface that gradually becomes higher from the first portion 13 side to the second portion 15 side. However, when viewed in more detail, the top surface 17a has projections and recesses. For example, as indicated by the reference numerals in the plan view in the center of Fig. 3 and Fig. 4, the top surface 17a has one or more (multiple in the illustrated example) recesses 17r (first recess 17ra and second recess 17rb). The multiple recesses 17r are distributed, for example, in the D1 direction and / or the D2 direction (both in the illustrated example).

[0072] As shown in the right cross-sectional view of FIG. 3 and FIG. 4, and as indicated by the reference numerals in FIG. 4, the portion of each recess 17r on the first region 13 side (+D1 side) can be regarded as a convex portion 17p (first convex portion 17pa and second convex portion 17pb). Examples of the convex portion 17p include a convex portion 17p (in the illustrated example, the first convex portion 17pa) between adjacent recesses 17r (in the illustrated example, the first concave portion 17ra and the second concave portion 17rb) in the D1 direction, and a convex portion 17p (in the illustrated example, the second convex portion 17pb) located on the first region 13 side (+D1 side) of the recess 17r (in the illustrated example, the second concave portion 17rb) located closest to the +D1 side. In addition, as shown in the upper cross-sectional view of FIG. 3 and the lower cross-sectional view of FIG. 3, a portion between adjacent recesses 17r in the D2 direction can also be regarded as a convex portion 17s.

[0073] Furthermore, the +D2 side portion of the recess 17r located closest to the +D2 side and the -D2 side portion of the recess 17r (not shown) located closest to the -D2 side can also be regarded as the protrusion 17s. However, these two protrusions 17s are unique among the multiple protrusions 17s in the illustrated example. Therefore, in the following description of the protrusions 17s, the -D2 side and +D2 side protrusions 17s may be ignored for convenience. The following description of the protrusions 17s may or may not be applied to the -D2 side or +D2 side protrusions 17s (or may not be applied).

[0074] (1.3.1. Position, shape and dimensions of each part in plan view) In a plan view, the position, shape, and dimensions of the recess 17r are arbitrary. In the description of the recess 17r in a plan view, the area surrounded by the edge of the recess such as the peak PK is mainly regarded as the recess 17r. Therefore, the description of the position, shape, and dimensions of the recess 17r in a plan view here is substantially the same as the description of the position, shape, and dimensions of the peak PK, etc. in a plan view. In the description of the cross-sectional view, the position away from the protrusion 17p or 17s (near the bottom of the recess) may be expressed as the recess 17r.

[0075] In the illustrated example, as described above, the upper surface 17a of the third portion 17 has a plurality of recesses 17r, and the plurality of recesses 17r are distributed in the D1 direction and the D2 direction. Unlike the illustrated example, for example, the upper surface 17a may have only one recess 17r, may have only a plurality of recesses 17r whose positions in the D2 direction are different (only one row of recesses 17r aligned in the D1 direction), or may have only a plurality of recesses 17r whose positions in the D1 direction are different (only one row of recesses 17r aligned in the D2 direction).

[0076] In the illustrated example, the recesses 17r are arranged in a plurality of rows in the D2 direction. The number of rows is arbitrary and may be, for example, 1, 2 (illustrated example) or 3 or more. In the illustrated example, the number of rows is two, and a first row consisting of a plurality of first recesses 17ra and a second row consisting of a plurality of second recesses 17rb located on the first portion 13 side (+D1 side) with respect to the first row are illustrated. In each row, the positions (e.g., the positions of the geometric centers) of the recesses 17r in the D1 direction are, for example, the same as each other. The pitches (e.g., the distance in the D2 direction between the geometric centers of the recesses 17r adjacent to each other in the D2 direction) of the different rows may be different from each other (illustrated example) or may be the same as each other. Unlike the illustrated example, the recesses 17r may be arranged in a staggered pattern, for example.

[0077] In the description of the embodiment, for convenience, the description and expression may be made on the assumption that the first recess 17ra and the second recess 17rb are arranged in the D1 direction as in the illustrated example. In this case, the terms "first recess 17ra" and "second recess 17rb" may be replaced with the terms "multiple recesses 17r arranged in the D1 direction" and / or "recesses 17r adjacent to each other in the D1 direction" unless a contradiction occurs. The term "first recess 17ra" may be replaced with the term "recess 17r closest to the second region 15 (-D1 side)" and / or "recess 17r relatively located on the second region 15 side among the recesses 17r adjacent to each other in the D1 direction" unless a contradiction occurs. The term "second recess 17rb" may be replaced with the term "recess 17r closest to the first region 13 (+D1 side)" and / or "recess 17r relatively located on the first region 13 side among the recesses 17r adjacent to each other in the D1 direction" unless a contradiction occurs.

[0078] Similarly, the terms "first convex portion 17pa" and "second convex portion 17pb" may be replaced with the terms "multiple convex portions 17p arranged in the D1 direction" and / or "convex portions 17p adjacent to each other in the D1 direction" unless a contradiction occurs. The term "first convex portion 17pa" may be replaced with the terms "convex portion 17p closest to the second region 15 (-D1 side)" and / or "convex portion 17p" relatively located on the second region 15 side among the convex portions 17p adjacent to each other in the D1 direction unless a contradiction occurs. The term "second convex portion 17pb" may be replaced with the terms "convex portion 17p closest to the first region 13 (+D1 side)" and / or "recess 17r" relatively located on the first region 13 side among the convex portions 17p adjacent to each other in the D1 direction unless a contradiction occurs.

[0079] Similarly, the terms first peak PK1 and second peak PK2 may be replaced with the terms of multiple peaks PK lined up in the D1 direction and / or peaks PK adjacent to each other in the D1 direction, unless a contradiction occurs. The term first peak PK1 may be replaced with the term peak PK closest to the second region 15 (-D1 side) and / or the peak PK relatively closer to the second region 15 among the peaks PK adjacent to each other in the D1 direction, unless a contradiction occurs. The term second peak PK2 may be replaced with the term peak PK closest to the first region 13 (+D1 side) and / or the peak PK relatively closer to the first region 13 among the peaks PK adjacent to each other in the D1 direction, unless a contradiction occurs.

[0080] In the illustrated example, the multiple recesses 17r (multiple first recesses 17ra or multiple second recesses 17rb) aligned in the D2 direction (from another perspective, at the same position in the D1 direction) have the same shape and dimensions. Unlike the illustrated example, the multiple recesses 17r aligned in the D2 direction may have different shapes and / or dimensions. For example, the multiple recesses 17r may have a larger (or smaller) length in the D2 direction and / or the D1 direction as they approach the edge of the third portion 17 in the D2 direction. Note that in the description of the embodiment, the description and expression may be made on the assumption that the multiple recesses 17r aligned in the D2 direction have the same shape and dimensions.

[0081] In the illustrated example, the multiple recesses 17r (first recesses 17ra and second recesses 17rb) arranged in the D1 direction (or, from another point of view, different positions in the D1 direction) are different from each other in at least the length in the D1 direction (for example, average length when the length in the D1 direction differs depending on the position in the D2 direction) as described later in detail. The multiple recesses 17r arranged in the D1 direction may have the same shape (illustrated example) or different shapes. In addition, the multiple recesses 17r arranged in the D1 direction may have the same length in the D2 direction (for example, average length when the length in the D2 direction differs depending on the position in the D1 direction for each recess 17r) or may have different lengths in the D2 direction (illustrated example). Unlike the description at the beginning of this paragraph, the multiple recesses 17r arranged in the D1 direction may have the same length in the D1 direction.

[0082] In the illustrated example, the recess 17r is square-shaped (rectangular in a higher-level concept). However, the shape of the recess 17r may be, for example, rectangular (except for a square). The rectangle may have either the D1 direction or the D2 direction as its longitudinal direction. The shape of the recess 17r may be other than rectangular (for example, circular, elliptical, or polygonal (except for rectangular)). Note that in the description of the embodiment, the description and expression may be given on the assumption that the shape of the recess 17r is rectangular.

[0083] The length of the recess 17r in the D1 direction is arbitrary. As can be understood from the above description that the number of recesses 17r in the D1 direction may be one, the length of the recess 17r in the D1 direction may be any value less than the length of the third portion 17 in the D1 direction. The reason why "less than" is used instead of "less than" is that at least one peak PK is positioned away from the first portion 13 and the second portion 15 in the D1-D3 cross section. The length of the recess 17r in the D1 direction may be, for example, 1 / 2 or more of the length of the third portion 17 in the D1 direction, or less than 1 / 2. In addition, the length of the recess 17r in the D1 direction may be shorter, equal to, or longer than the length of the third portion 17 in the D1 direction of the non-arrangement region of the recess 17r (the portion on the +D1 side of the second peak PK2).

[0084] The length of the recess 17r in the D2 direction is also arbitrary. As can be understood from the above description that the number of recesses 17r in the D2 direction may be one, the length of the recess 17r in the D2 direction may be any value equal to or less than the length of the third portion 17 in the D2 direction.

[0085] In the illustrated example, the recesses 17r are arranged closer to the first region 13 (+D1), and the length in the D1 direction (for example, the average length when the length in the D1 direction varies depending on the position in the D2 direction) is larger. That is, the length in the D1 direction of the second recess 17rb is smaller than the length in the D1 direction of the first recess 17ra. In such an embodiment, the ratio or difference between the lengths in the D1 direction of the different sizes is arbitrary. For example, in two recesses 17r adjacent to each other in the D1 direction, the length in the D1 direction of the recess 17r (for example, the second recess 17rb) located relatively closer to the first region 13 (+D1 side) may be 1.2 times or more, 1.5 times or more, or 2 times or more than the length in the D1 direction of the recess 17r (for example, the first recess 17ra) located relatively closer to the second region 15 (-D1 side). Unlike the above description, between two recesses 17r adjacent to each other in the D1 direction, the length in the D1 direction of the recess 17r relatively on the +D1 side may be the same as the length in the D1 direction of the recess 17r relatively on the -D1 side, or the former may be shorter than the latter.

[0086] As described above, in the illustrated example, the recess 17r on the +D1 side has a greater length in the D1 direction. Also, in the illustrated example, the recess 17r is a square. Therefore, the recess 17r on the +D1 side has a greater length in the D2 direction. However, as can be understood from the above description, in an embodiment in which the recess 17r on the +D1 side has a greater length in the D1 direction, the recesses 17r aligned in the D1 direction (at different positions in the D1 direction) may have the same length in the D2 direction. Also, contrary to the illustrated example, the recess 17r on the +D1 side may have a greater length in the D1 direction but a smaller length in the D2 direction.

[0087] (1.3.2. Shape in Cross Section) 4, in the D1-D3 cross section, peaks PK (first peak PK1 and second peak PK2) of convex portion 17p are located between the upper surface of first portion 13 and the upper surface of second portion 15 in the D3 direction. As a result, upper surface 17a of third portion 17 forms an inclined surface that is positioned closer to +D3 as it approaches second portion 15.

[0088] In the D1-D3 cross section, the portion of recess 17r closest to the -D3 side (hereinafter sometimes referred to as the bottom) is located, in terms of the position in the D3 direction, between the upper surface of first portion 13 and the upper surface of second portion 15. From this perspective as well, upper surface 17a is an inclined surface as a whole.

[0089] In the D1-D3 cross section, the multiple peaks PK are located closer to the +D3 side as they are closer to the second portion 15. Specifically, in the illustrated example, the first peak PK1, which is relatively closer to the second portion 15, is located closer to the +D3 side than the second peak PK2, which is relatively closer to the first portion 13. From this perspective, the upper surface 17a as a whole is an inclined surface.

[0090] Furthermore, in the D1-D3 cross section, with respect to the position in the D3 direction, the lowermost parts of the multiple recesses 17r are located on the +D3 side as they are closer to the second portion 15. In the illustrated example, the lowermost part of the first recess 17ra, which is relatively closer to the second portion 15, is located on the +D3 side of the lowermost part of the second recess 17rb, which is relatively closer to the first portion 13. From this perspective as well, the upper surface 17a as a whole is an inclined surface.

[0091] As shown in the upper and lower cross-sectional views of FIG. 3, in the D2-D3 cross section, the positions, shapes and sizes of the multiple convex portions 17s (and the multiple concave portions 17r) are the same as each other (excluding unique portions such as ends). Therefore, in the D2-D3 cross section, the top surface 17a of the third portion 17 has a constant height in the D3 direction as a whole. However, unlike the illustrated example, the positions, shapes and / or sizes of the multiple convex portions 17s (and / or the multiple concave portions 17r) may be different from each other in the D2-D3 cross section.

[0092] Although not shown, the position of the peak PK of one convex portion 17p in the D3 direction may or may not be constant in the D2 direction. An example of the latter mode is a mode in which the position of the peak PK is located on the +D3 side closer to the intersection with the convex portion 17s.

[0093] In an embodiment in which the position of the peak PK of one convex portion 17p in the D3 direction is not constant in the D2 direction, for example, the position in the D2 direction where the first peak PK1 takes a representative value (for example, the lowest value, the highest value, or the average value) with respect to the position in the D3 direction may differ from the position in the D2 direction where the second peak PK2 takes a representative value with respect to the position in the D3 direction. For example, when the position and / or length of the first recess 17ra in the D2 direction and the position and / or length of the second recess 17rb in the D2 direction are different, the first peak PK1 and the second peak PK2 have different positions in the D2 direction where the representative value of the position in the D3 direction is taken (period in another perspective). In this case, for example, the representative values ​​of the positions in the D3 direction of the first peak PK1 and the second peak PK2 may be compared.

[0094] As can be understood from the above, it may not be reasonable to consider the description of the D1-D3 cross section (sometimes referred to as the "first cross section") in the present disclosure as focusing on one cross section. Therefore, with respect to the description of the D1-D3 cross section in the present disclosure, the position in the D3 direction referred to does not necessarily have to be the same as the position in the D2 direction. From another perspective, each cross section such as FIG. 4 may basically be considered to show one cross section (one plane), but may also be considered to show multiple cross sections (multiple planes) with different positions in the D2 direction and ranges in the D1 direction in the corresponding ranges in the D1 direction.

[0095] For example, a representative value of the position of the first peak PK1 in the D3 direction and a representative value of the position of the second peak PK2 in the D3 direction may appear together in one cross section, and cross-sectional views such as Fig. 4 may be considered to show such a cross section. Also, for example, when comparing an arbitrary position of the first peak PK1 in the D2 direction with an arbitrary position of the second peak PK2 in the D2 direction, if the requirements described in this disclosure regarding the relative positions in the D3 direction of the first peak PK1 and the second peak PK2 are met, the above discussion regarding the success or failure of the requirements is not necessary.

[0096] Regardless of whether the position of the peak PK of one convex portion 17p in the D3 direction is constant in the D2 direction or not, when the description of the first cross section (D1-D3 cross section) is taken to be for one cross section, the requirements related to the surface shape described in the description of the embodiment may be satisfied for a cross section at an arbitrary position in the D2 direction and / or an arbitrary number of cross sections. For example, the requirements related to the surface shape may be satisfied only for a D1-D3 cross section at a specific position in the D2 direction, or may be satisfied for 30% or more, 50% or more, 60% or more, 80% or more, or all of an infinite number of D1-D3 cross sections at different positions in the D2 direction.

[0097] Although the peak PK is taken as an example, the same applies to the convex portion 17p and the concave portion 17r. Furthermore, although the comparison of the position in the D3 direction is taken as an example, the same applies to the comparison of the position in the D1 direction. Furthermore, although the D1-D3 cross section is taken as an example, the same applies to the D2-D3 cross section.

[0098] Although not particularly shown, the position of the peak PK of one convex portion 17s in the D3 direction may or may not be constant in the D1 direction. Examples of the latter mode include a mode in which the position of the peak PK is located on the +D3 side closer to the second portion 15 (-D1 side) and / or a mode in which the peak PK is located on the +D3 side closer to the intersection with the convex portion 17p. In this case, the change in the position of the peak PK in the D3 direction may or may not be similar to the change in the position of the peak PK in the D3 direction at a position other than the position of the peak PK of the convex portion 17s (for example, the change in the right side in FIG. 3 and the upper surface 17a in FIG. 4).

[0099] In the D1-D3 cross section, the specific positions of the multiple peaks PK in the D1 and D3 directions are arbitrary. For example, the line connecting the boundary between the second region 15 and the third region 17, the multiple peaks PK, and the boundary between the third region 17 and the first region 13 in this order may be linear, may have an upwardly bulging shape, or may have a downwardly dented shape. The angle of the line is arbitrary. For example, the inclination angle of the line with respect to the D1 direction may be 35° or less or 30° or less at any position or at any position on the +D1 side from the first peak PK1. Also, for example, the inclination angle of the line connecting the adjacent peaks PK with respect to the D1 direction may be 30° or less or 20° or less.

[0100] (1.3.3. Details of the shape in the D1-D3 cross section) 4, in the D1-D3 cross section, the upper surface 17a of the third portion 17 (convex portion 17p in another respect) may have a convex curve Lp including a peak PK (first peak PK1 or second peak PK2). The curve Lp may extend over an appropriate range in the D1-D3 cross section.

[0101] In the illustrated example, the curve Lp including the first peak PK1 extends to the bottom of the first recess 17ra on the first recess 17ra side (-D1 side). Note that in the illustrated example, the portion of the first recess 17ra on the -D1 side of the bottom is linear. Therefore, at the position of intersection, a corner formed by the intersection of a straight line and a curve is located.

[0102] In the illustrated example, the curve Lp including the first peak PK1 extends to an inflection point (reference symbol omitted) located between the first peak PK1 and the bottom of the second recess 17rb on the second recess 17rb side (+D1 side). Note that in the illustrated example, the curve Lp from the inflection point to the bottom of the second recess 17rb and the vicinity of the bottom of the second recess 17rb are concavely curved.

[0103] In the illustrated example, the curve Lp including the second peak PK2 extends to an inflection point located between the bottom of the second recess 17rb and the second peak PK2 on the second recess 17rb side (-D1 side). In the illustrated example, the curve from the inflection point to the bottom of the second recess 17rb and the vicinity of the bottom of the second recess 17rb are concave curved.

[0104] In the illustrated example, the curve Lp including the second peak PK2 extends on the first portion 13 side (+D1 side) to a position where it intersects with the upper surface of the first portion 13. In the illustrated example, the upper surface of the first portion 13 is linear. Therefore, at the above-mentioned intersecting position, a corner formed by the intersection of a straight line and a curved line is located.

[0105] Unlike the illustrated example, in an embodiment in which three or more peaks PK are located, the -D1 side portion of the curve Lp including the peak PK sandwiched between two peaks PK in the D1 direction may be referred to in the above and below explanations regarding the -D1 side portion of the curve Lp including the second peak PK2. The +D1 side portion of the curve Lp including the peak PK sandwiched between two peaks PK in the D1 direction may be referred to in the above and below explanations regarding the +D1 side portion of the curve Lp including the first peak PK1.

[0106] Unlike the illustrated example, the convex curve Lp including the peak PK may change to a straight line midway. For example, the portion of the first convex portion 17pa on the first concave portion 17ra side (-D1 side) may change from the curve Lp to a straight line and intersect with the straight line of the portion of the first concave portion 17ra on the -D1 side. Also, for example, the portion of the first convex portion 17pa on the second concave portion 17rb side (+D1 side) and / or the portion of the second convex portion 17pb on the second concave portion 17rb side (-D1 side) may change from the curve Lp to a straight line and connect with the concave curve near the bottom of the second concave portion 17rb. Also, for example, the portion of the first portion 13 (+D1 side) of the second convex portion 17pb may change from the curve Lp to a straight line and intersect with the upper surface of the first portion 13. Note that the portion changing from the curve Lp to a straight line may or may not be smoothly connected to the curve so that no corner is formed.

[0107] As can be understood from the explanation in the previous paragraph, unlike the illustrated example, a corner where two straight lines intersect may be located at the bottom of first recess 17ra (recess 17r closest to second region 15). Also, a corner where two straight lines intersect may be located at the boundary between second protrusion 17pb (protrusion 17p closest to first region 13) and first region 13.

[0108] Unlike the illustrated example, a corner may be located near the bottom of the second recess 17rb (in other words, the recess 17r between the two protrusions 17p) without a concave curved shape. For example, as described above, the portion on the +D1 side of the first protrusion 17pa and the portion on the -D1 side of the second protrusion 17pb may change from a curved shape to a straight line, and the straight line-shaped portions may intersect with each other to form a corner located at the bottom of the second recess 17rb. Also, a corner may be located near the bottom of the second recess 17rb by intersecting a straight line with a convex curve, or by intersecting curves with different curvatures (for example, convex curves).

[0109] Unlike the illustrated example, a concave curve may be located near the bottom of the first concave portion 17ra (the concave portion 17r closest to the second region 15) instead of a corner. From another perspective, a portion of the curve Lp including the first peak PK1 on the first concave portion 17ra side (-D1 side) may extend to an inflection point between that portion and the concave curve. Also, the second convex portion 17pb (the convex portion 17p closest to the first region 13) and the upper surface of the first region 13 may be smoothly connected without a corner by, for example, the second convex portion 17pb presenting a concave curve near the boundary with the upper surface of the first region 13. From another perspective, a portion of the convex curve Lp including the second peak PK2 on the +D1 side may extend to an inflection point between that portion and the concave curve.

[0110] Unlike the illustrated example, a convex curve may be located at the boundary between the upper surface of the second portion 15 and the first recess 17ra, instead of a corner. Alternatively, the upper surface of the second portion 15 may be straight, while the intersection of the first recess 17ra with the second portion 15 may be a convex curve, and a corner where the straight line and the curve intersect may be located at the boundary between the two. As can be understood from the above description, the portion of the first recess 17ra connected to the second portion 15 may have a convex curve extending from the second portion 15, and this curve may extend to the lowest portion of the first recess 17ra, or may extend to an inflection point or a straight line midway.

[0111] In the above description, the portion expressed as a corner in comparison with the curve Lp including the peak PK (for example, the boundary between the upper surface of the second portion 15 and the upper surface 17a of the third portion 17) may have a curve or a step when viewed microscopically. In this case, the length of the curve or the height of the step is, for example, less than 1 μm or less than 0.1 μm. In other words, depending on the overall size of the quartz crystal element 1, if a curve is confirmed over a length of, for example, 0.5 μm or more or 1 μm or more, it may be said that the upper surface 17a of the third portion 17 has a curve. For example, if a curve can be confirmed over a length of 0.1 μm or more, 0.5 μm or more, or 1 μm or more (for example, the length along the upper surface 17a or the length of a straight line connecting the ends of the curve) from the -D1 side of the peak PK to the +D1 side of the peak PK, it may be said that the upper surface 17a has a curve Lp including the peak PK. When viewed extremely microscopically, the curve Lp may include a corner or a straight line (for example, a length of less than 0.1 μm).

[0112] Moreover, the radius of curvature (or, from another point of view, the curvature) of various curves (such as the curve Lp) is arbitrary. Moreover, the radius of curvature may be constant over a predetermined range, or may vary. For example, the radius of curvature of the curve Lp including the peak PK may increase with increasing distance from the peak PK. Moreover, the curve Lp may smoothly connect to an inflection point or a straight line. Moreover, in the vicinity of the peak PK (a relatively narrow range), the radius of curvature of the curve Lp may be constant, or may increase with increasing distance from the peak PK. The absolute value (μm) of the radius of curvature is also arbitrary.

[0113] (1.3.4. Details of shape in D2-D3 cross section) The above detailed description of the shape in the D1-D3 cross section may be appropriately applied to the shape in the D2-D3 cross section. For example, in the D2-D3 cross section, the convex portion 17s may have a curve including a peak PK, and in this case, the length of the curve is arbitrary. Furthermore, in the D2-D3 cross section, a concave curve or a corner may be located near the bottom of the concave portion 17r. In the D2-D3 cross section, the convex portion 17s (or the concave portion 17r) may or may not include a straight line.

[0114] (2. Examples of using quartz crystal elements) 5 is a cross-sectional view of a quartz crystal device 101 as an example of the use of the quartz crystal element 1. This figure shows a cross section at a position corresponding to line VV in FIG.

[0115] The crystal device 101 is, for example, an electronic component that has a generally rectangular parallelepiped shape. The dimensions of the crystal device may be any appropriate size. For example, the length of the long or short side in a plan view is 0.6 mm or more and 2.0 mm or less, and the thickness (D3 direction) is 0.2 mm or more and 1.5 mm or less. The crystal device 101 is, for example, surface-mounted with its bottom surface facing the top surface of a mounting base (e.g., a circuit board) not shown.

[0116] The crystal device 101 is configured as, for example, an oscillator that contributes to the generation of an oscillation signal in which the signal strength (for example, voltage and / or current) oscillates at a certain frequency. The crystal device 101 includes, for example, a crystal element 1 that generates the vibration used to generate the oscillation signal, and a package 103 that packages the crystal element 1.

[0117] The package 103 has, for example, a base 107 that supports the crystal element 1, and a lid 109 that is bonded to the base 107 and seals the crystal element 1. The crystal element 1 is supported by being bonded to the base 107 by, for example, a conductive bonding material 105. The internal space of the package 103 is, for example, a vacuum or filled with an appropriate gas (for example, nitrogen).

[0118] The base 107 has, for example, a recess for accommodating the crystal element 1. From another perspective, the base 107 has a flat substrate portion 107a and a frame portion 107b that runs along the edge of the upper surface of the substrate portion 107a. The base 107 having the substrate portion 107a and the frame portion 107b is mainly made of an insulating material such as a ceramic material. The lid 109 is mainly made of, for example, a metal, and is joined to the upper surface of the frame portion 107b by seam welding or the like.

[0119] The package 103 has conductors for electrically connecting the crystal element 1 and a mounting base (not shown) on which the crystal device 101 is mounted. For example, the package 103 has pads 111 for mounting the crystal element 1, external terminals 113 for mounting the crystal device 101 on a mounting base, and wiring conductors (not shown) for connecting the two.

[0120] The pads 111 are formed of a conductive layer located on the upper surface of the substrate portion 107a. The external terminals 113 are formed of a conductive layer located on the lower surface of the substrate portion 107a. The wiring conductors (not shown) are formed to include through conductors that vertically penetrate the substrate portion 107a. The material of these conductors is, for example, a metal.

[0121] The crystal element 1 is bonded to the pad 111 by the bonding material 105. As a result, the crystal element 1 is supported by the base 107 and electrically connected to the package 103. More specifically, the crystal element 1 is bonded to the pad 111 at one end thereof and supported in a cantilever shape. The bonding material 105 is mainly composed of, for example, a conductive adhesive. The conductive adhesive is composed of a thermosetting resin mixed with a metal filler.

[0122] In the illustrated example, the bonding material 105 is bonded only to the lower surface side (-D3 side) of the connection electrode 11. However, the bonding material 105 may be bonded to the side surface side (-D1 side and / or -D2 side or +D2 side) in addition to the lower surface side, or may be bonded to the upper surface side.

[0123] The external terminals 113 are joined to pads of a mounting substrate (not shown) by soldering, for example, so that the crystal device 101 is supported and electrically connected to the mounting substrate.

[0124] The quartz crystal element 1 may be used in various other ways in addition to the above-mentioned examples of use.

[0125] For example, the resonator may have other electronic elements such as a thermistor in addition to the crystal element 1. The crystal device (piezoelectric device) may be an oscillator having an integrated circuit element (IC) that applies a voltage to the crystal element 1 to generate an oscillation signal, in addition to the crystal element 1. The piezoelectric device may be equipped with a thermostatic oven.

[0126] In the piezoelectric device, the structure of the package that packages the crystal element 1 may be appropriately configured. For example, the package may have an H-shaped cross section with recesses on the upper and lower surfaces. The package may also be configured with a substrate-like base body (a base body without a recess) and a cap-like lid body that covers the base body.

[0127] (3. Manufacturing method of quartz crystal element) The quartz crystal element 1 may be manufactured by various methods. For example, the manufacturing method of the quartz crystal element 1 may be the same as a conventional manufacturing method, except for the process of forming the surface shape of the third portion 17. Although not particularly illustrated, an example will be described below.

[0128] First, a quartz crystal wafer is prepared. The wafer is used to produce a large number of quartz crystal blanks 3. Such a wafer is cut at an angle related to the above-mentioned AT cut, and is processed to a thickness equal to that of the second portion 15.

[0129] Next, a mask for etching (hereinafter sometimes referred to as the "first mask") is formed on both main surfaces of the wafer. The first mask has, for example, a slit (opening) that extends along most of the outer edge of the area that will become each quartz crystal plate 3. In other words, the first mask overlaps the area that will become the quartz crystal plate 3 (first portion 13, second portion 15, and third portion 17) and the area that will become the frame-shaped portion (waste space) for supporting the quartz crystal plate 3. Then, the wafer is etched from both main surfaces through the first mask. The etching is, for example, wet etching in which the wafer is immersed in a chemical solution. As a result, the periphery of the area that will become the quartz crystal plate 3 is etched, and the outer shape of the quartz crystal plate 3 is formed.

[0130] Next, the first mask is removed, and a new mask for etching (hereinafter sometimes referred to as a "second mask") is formed on both main surfaces of the wafer. The second mask overlaps the upper and lower surfaces of the region that will become the second portion 15 (it does not overlap the region that will become the first portion 13). The second mask may be formed by removing a part of the first mask. Then, the wafer is etched from both main surfaces through the second mask. As a result, the region that will become the first portion 13 becomes thinner than the region that will become the second portion 15.

[0131] The second mask is then removed, and the conductor pattern 5 is formed. The conductor pattern 5 may be formed, for example, by depositing a metal film through a mask formed on the surface of the quartz crystal plate 3. Alternatively, the conductor pattern 5 may be formed by depositing a metal film over the entire surface or most of the quartz crystal plate 3, and then etching the metal film through a mask. The film may be formed by an appropriate method such as sputtering.

[0132] After the conductive pattern 5 is formed, the quartz crystal plate 3 is singulated by, for example, bending or cutting the connection between the quartz crystal plate 3 and the frame-shaped portion of the wafer that supports the quartz crystal plate 3. During and / or after singulation, the second portion 15 may be used to hold the quartz crystal element 1. For example, the quartz crystal element 1 may be held by a jig by adsorbing and holding the second portion 15.

[0133] The surface shape of the third portion 17 may be realized by various methods, one example of which will be described below.

[0134] 6 is a schematic diagram showing a wafer 51 on which the above-mentioned second mask 53 (a mask for etching to thin the first portion 13) is formed. This figure corresponds to the plan view on the central side of FIG. 3 and the cross-sectional view on the right side of FIG. 3.

[0135] 6 and 3, the second mask 53 overlaps not only the region that will become the second portion 15 but also part of the region that will become the third portion 17. Specifically, the second mask 53 has a frame-shaped portion 53f that overlaps the region that will become the peaks PK of the protrusions 17p and 17s. From another perspective, the second mask 53 has openings 53a (first opening 53aa and second opening 53ab) in a region that corresponds to the region that will become the recess 17r (first recess 17ra and second recess 17rb).

[0136] 7 is a diagram showing a state where etching has been performed through the second mask 53. This figure corresponds to FIG.

[0137] When etching is performed through the second mask 53, an inclined surface (a crystal plane from another point of view) appears in the etched region due to the anisotropy of the quartz crystal with respect to etching. As a result, a triangular recess is formed in a cross-sectional view below the opening 53a, as shown by the solid line on the -D1 side of the first recess 17ra, the line Lv2 (dotted line) located on the +D1 side of the solid line, and the line Lv1 (dashed line) located on the +D1 side of the solid line. The larger the diameter (in the D1 direction and / or the D2 direction) of the opening 53a, the deeper the triangular recess becomes.

[0138] Here, by appropriately setting the etching conditions, etching can be allowed to proceed even directly below the frame portion 53f by so-called side etching. For example, the width of the frame portion 53f is made sufficiently narrow, or the etching time is made sufficiently long. By such etching, the position in the D3 direction of the portion of the wafer 51 directly below the frame portion 53f (i.e., the portion that becomes the peak PK) becomes lower.

[0139] The effect of side etching to lower the peak PK becomes stronger as the diameter (D1 direction and / or D2 direction) of the opening 53a becomes larger. The reason for this is that, for example, the larger the diameter, the easier it is for the chemical solution to enter the recess. Also, the larger the diameter of the opening 53a, the deeper the normal etching is performed, so the side etching is performed from a deeper position. And, since the diameter of the opening 53a is larger on the first portion 13 side (+D1 side), the peak PK becomes lower on the first portion 13 side.

[0140] Since etching that cuts the surface of the wafer 51 downward starts from above, side etching, which is based on the premise that the surface is cut down to form the inner circumferential surface of the recess, also tends to occur earlier at the top. Also, once side etching starts, the surface area in contact with the chemical solution increases at the top, so the side etching tends to progress faster at the top. Due to this effect, the surface of the wafer 51 becomes curved near the peak PK. Also, by lengthening the etching time, the surface of the wafer 51 becomes curved even at the recess 17r.

[0141] The line Lv1 corresponds to an inclined surface (crystal surface) in an embodiment in which the second mask 53 does not have an opening 53a and extends to the position of the second peak PK2 in the D1 direction. The inclination of the third portion 17 as a whole is gentler than the inclination of the line Lv1. The inclination of the third portion 17 as a whole may be evaluated, for example, by the inclination angle with respect to the D1 direction at any position of a line connecting the boundary between the upper surface of the second portion 15 and the upper surface 17a of the third portion 17, the multiple peaks PK, and the boundary between the upper surface 17a and the upper surface of the first portion 13 in this order, or the average value of the inclination angle with respect to the D1 direction over the entire line. The line Lv1 is inclined at an angle of more than 35° with respect to the D1 direction, for example.

[0142] The surface shape of the third portion 17 may be realized by other methods instead of or in addition to the above-mentioned methods. For example, although not particularly shown, the number of etchings (the number of masks) may be further increased. Specifically, for example, after etching using the first mask (etching the outer edge of the quartz crystal plate 3), etching is performed through a third mask having an area equivalent to that of the second mask. The third mask may have the same configuration as the second mask 53, or may have a different configuration from the second mask 53 (for example, a configuration without the first opening 53aa). Next, etching is performed through a fourth mask that covers at least the second portion 15 and the position of the first peak PK1 and does not cover the position of the second peak PK2. As a result, the second peak PK2 is etched to be lower than the first peak PK1, and is curved by etching from various directions. The fourth mask may be configured by removing a portion of the second mask 53 on the +D1 side from the position of the first peak PK1 in the D1 direction, or may have a different configuration from such a configuration. Regarding the latter, for example, in an embodiment in which the third mask has the first opening 53aa, the fourth mask does not have to have an opening corresponding to the first opening 53aa.

[0143] (4. Other Examples) (4.1. Other Examples of Surface Shape of the Third Region) 8 is a schematic diagram showing another example of the surface shape of the third portion 17. This diagram corresponds to the plan view on the central side of FIG. 3 and the cross-sectional view on the right side of FIG.

[0144] As shown in this figure, and as already mentioned, the number of peaks PK on the D1-D3 cross section may be one. In other examples described below, for ease of illustration, an example in which the number of peaks PK on the D1-D3 cross section is one may be taken as an example. Just to be clear, in other examples described below, the number of peaks PK on the D1-D3 cross section may be multiple (2 or more).

[0145] 9(a) to 9(c) are diagrams showing other examples of the surface shape of the third portion 17. These diagrams correspond to the cross-sectional view on the right side of FIG.

[0146] As shown in Fig. 9(a), the position of the peak PK in the D3 direction may be the same as the position of the upper surface of the second portion 15 in the D3 direction. Although not particularly shown, in an embodiment in which two or more peaks PK are present, the positions of the two or more peaks PK in the D3 direction may be the same as each other. This position may be the same as the position of the upper surface of the second portion 15 in the D3 direction as in Fig. 9(a), or may be different. The position of the bottom of the recess 17r in these embodiments is also arbitrary.

[0147] 9(a), the upper surface 17a of the third portion 17 may not include curves and may be composed of straight lines only in the D1-D3 cross section. Although not shown in particular, the upper surface 17a of the third portion 17 may not include curves and may be composed of straight lines only in the D2-D3 cross section.

[0148] The surface shape shown in FIG. 9(a) may be realized by any suitable method. For example, in the manufacturing method described with reference to FIG. 7, the peak PK is lowered or a curve Lp including the peak PK is realized by side etching below the frame-shaped portion 53f of the second mask 53. The other examples shown in FIG. 9(a) may be realized by reducing the side etching. In this case, strictly speaking, the peak PK may not be a corner, but may be a flat surface having an area corresponding to the frame-shaped portion 53f.

[0149] As shown in FIG. 9(b), the peak PK does not have to be located on the +D3 side of the portion on the second portion 15 side (-D1 side) of the peak PK. In other words, the recess 17r does not have to have a portion located on the -D3 side of the peak PK in the D3 direction. From another perspective, the protrusion 17p does not have to be a portion that bulges outward from the quartz crystal plate 3 with respect to a line parallel to the D1 direction. It is sufficient to be able to conceptualize the protrusion 17p in a rational manner.

[0150] For example, a portion of the quartz crystal plate 3 that is located outside a straight line (e.g., line LS1 or LS2) connecting any two positions (including the boundary between the first portion 13 and the second portion 15) on the upper surface 17a can be regarded as the convex portion 17p. The portion with the maximum height (distance in the direction perpendicular to line LS1) from the straight line (line LS1 or LS2) can be regarded as the peak PK.

[0151] The line LS1 illustrated in FIG. 9(b) is a straight line selected so as to obtain the peak PK with the maximum height. For example, such a straight line is a line that is tangent to one recess 17r and also tangent to an end of the upper surface 17a (the boundary with the first region 13 or the second region 15) or another recess 17r. The line LS2 illustrated in FIG. 9(b) is a straight line that connects the boundary between the first region 13 and the third region 17 and the boundary between the second region 15 and the third region 17.

[0152] 9(b), as an example of a surface shape in which the peak PK cannot be defined based on a line parallel to the D1 direction but can be defined based on the line LS1 or LS2, a shape in which the -D1 side portion of the peak PK is parallel to the D1 direction is shown. Other shapes include, for example, a shape in which the -D1 side portion of the peak PK is inclined so as to be positioned lower toward the +D1 side (however, does not reach the inclination of the line LS1 or LS2).

[0153] The surface shape shown in Fig. 9(b) may be realized by any suitable method. For example, in the manufacturing method described with reference to Fig. 7, the peak PK is lowered by side etching below the frame portion 53f of the second mask 53. By further advancing such side etching, the surface shape shown in Fig. 9(b) may be realized.

[0154] Also, the surface shape shown in FIG. 9(b) may be realized by increasing the number of etchings (the number of masks). Specifically, for example, after etching using the first mask, etching is performed using a fifth mask that extends from the edge on the -D1 side of the region that will become the second portion 15 to the position of the peak PK in the D1 direction. The fifth mask does not have an opening 53a (frame-shaped portion 53f). Next, etching is performed using a sixth mask that overlaps only the region that will become the second portion 15.

[0155] 9(c), the top surface 17a of the third portion 17 may have a shape in which a peak PK (convex portion 17p) can be identified based on a straight line such as line LS2, but a concave portion 17r located on the second portion 15 side (-D1 side) of the peak PK cannot be identified. Such a shape can be realized, for example, by performing etching through a sixth mask that overlaps only the region that becomes the second portion 15 after etching using a first mask, and by allowing side etching directly below the edge of the sixth mask on the +D1 side to proceed sufficiently.

[0156] (4.2. Other examples of the location of the third portion) 10(a) to 11(b) are schematic plan views showing other examples of the position of the third portion 17 (the second portion 15 from another perspective). In these figures, for ease of illustration, the extraction electrode 9 is omitted.

[0157] 10(a) has a second portion 15 and a third portion 17 along two sides of a first portion 13. In other words, the second portion 15 and the third portion 17 are formed in an L-shape. One or more (multiple in the illustrated example) recesses 17r (or, from another perspective, peaks PK of protrusions 17p or protrusions 17s) are located along each side (two sides) of the L-shape third portion 17.

[0158] In this way, the second portion 15 and the third portion 17 do not have to be entirely located on one side (-D1 side) of the first direction (D1 direction) with respect to the first portion 13. That is, the second portion 15 and the third portion 17 only need to have a portion located on the -D1 side with respect to the first portion 13. Note that, unlike the description here, only the portions located on the -D1 side with respect to the first portion 13 may be regarded as the second portion and the third portion.

[0159] Although not particularly shown, the two sides of the first portion 13 on which the third portion 17 is located may be different from the example shown in the figure. For example, the two sides may be one side on the -D1 side and one side on the +D2 side, or one side on the -D1 side and one side on the +D1 side.

[0160] 10(b) has a second portion 15 and a third portion 17 along three sides of a first portion 13. In other words, the second portion 15 and the third portion 17 are formed in a U-shape. One or more (multiple in the illustrated example) recesses 17r (or, from another perspective, peaks PK of protrusions 17p or protrusions 17s) are located along each side (three sides) of the third portion 17 of the U-shape.

[0161] Although not particularly shown, the three sides of the first portion 13 on which the third portion 17 is located may be different from the example shown in the drawing. For example, the three sides may be one side on the -D1 side, one side on the -D2 side, and one side on the +D2 side, or one side on the -D1 side, one side on the +D2 side, and one side on the +D1 side.

[0162] The quartz crystal plate 3G shown in FIG. 11(a) has a second portion 15 and a third portion 17 along the four sides of the first portion 13. In other words, the second portion 15 and the third portion 17 are formed in a rectangular ring shape. From another perspective, the quartz crystal plate 3G is an inverted mesa type in which the area where the excitation electrode 7 overlaps is thinner than the outer periphery. And, one or more (multiple in the illustrated example) recesses 17r (from another perspective, peaks PK of protrusions 17p or protrusions 17s) are located along each side (four sides) of the ring-shaped third portion 17.

[0163] 10(a), the quartz crystal blank 3H shown in Fig. 11(b) has a second portion 15 and a third portion 17 along two sides of the first portion 13. However, one or more (multiple in the illustrated example) recesses 17r (or, from another perspective, peaks PK of protrusions 17p or protrusions 17s) are not located over the entire third portion 17 (two sides), but are located on only a portion of the third portion 17 (for example, only one side).

[0164] Unlike the description here, only a portion where one or more concave portions 17r (or, from another point of view, peaks PK of convex portions 17p or convex portions 17s) are located may be regarded as the third portion among the portions located between first portion 13 and second portion 15. For example, in the example of Fig. 11(b), only one side on the -D1 side of L-shaped third portion 17 may be regarded as the third portion, and one side on the -D2 side may be regarded as a portion different from the third portion.

[0165] The portion (for example, one side) where the recess 17r is located may be any portion of the third portion 17. For example, the portion where the recess 17r is located may be a portion of the third portion 17 on the side (-D1 side) where the connection electrode 11 is located with respect to the first portion 13 as in the illustrated example, or may be another portion. Although the drawing electrode 9 is not illustrated here, the portion where the recess 17r is located may be a portion of the third portion 17 where the drawing electrode 9 (the conductor pattern 5 from another point of view) is located, or may be a portion where the conductor pattern 5 is not located. Note that instead of or in addition to the drawing electrode 9, a part of the connection electrode 11 may be located on the recess 17r.

[0166] Although not specifically shown, even in an embodiment in which the third portion 17 is located over three or four sides of the first portion 13 (FIGS. 10(b) and 11(c)), one or more recesses 17r (peaks PK) may be located only on some of the sides. The positions of the some of the sides relative to the first portion 13 are also arbitrary. For example, the some of the sides may or may not include one side on the side where the connection electrode 11 is located (-D1 side).

[0167] Although not particularly shown, the one or more recesses 17r may be located only in a portion of the third portion 17 that corresponds to one side of the first portion 13. For example, the two or more recesses 17r may be located only in both end portions of one side on the -D1 side (portions that overlap with two connection electrodes 11 in the range in the D2 direction), and may not be located in any portion therebetween.

[0168] 10(a) to 11(b), two connection electrodes 11 are located on one side of the second portion 15 that spans two or more sides of the first portion 13. However, the two connection electrodes 11 may be located on different sides of the second portion 15. Also, similar to the embodiment, the connection electrode 11 may have a portion located in the third portion 17 (and further in the first portion 13).

[0169] In the examples of Fig. 10(a) to Fig. 11(b), the drawing electrode 9 is omitted. As described in the explanation of the first embodiment, the position, shape, and size of the drawing electrode 9 are arbitrary as long as the excitation electrode 7 and the connection electrode 11 can be connected. For example, in another example of Fig. 10(a), the drawing electrode 9 connected to the connection electrode 11 on the -D2 side may extend from the excitation electrode 7 generally toward the -D1 side to reach the third portion 17 and the second portion 15 on the -D1 side, or may extend from the excitation electrode 7 toward the -D2 side to reach the third portion 17 and the second portion 15 on the -D2 side, then change direction on the second portion 15 to extend toward the -D1 side, and reach the third portion 17 and the second portion 15 on the -D1 side.

[0170] (4.3. Other examples of thickness of the third portion) 12 is a cross-sectional view showing another example (quartz crystal element 1I according to another example) relating to the thickness of the third portion. This figure corresponds to a part of FIG.

[0171] As mentioned in the description of the first embodiment, and as shown in Fig. 12, the second portion 15I may be thicker on only one side in the thickness direction (e.g., the -D3 side) than the first portion 13. The quartz crystal plate 3I shown in Fig. 12 is an example of such an embodiment. Just to be clear, although not shown in Fig. 12, the third portion 17I has one or more peaks PK on the inclined surface (the surface on the -D3 side) as in the embodiment.

[0172] (5. Summary of the First Embodiment) As described above, in this embodiment, the piezoelectric element (quartz crystal element 1) has a piezoelectric body (quartz crystal blank 3), an excitation electrode 7, an extraction electrode 9, and a connection electrode 11. The quartz crystal blank 3 has a first portion 13, a second portion 15, and a third portion 17. In a plan view, at least a portion of the second portion 15 is located on one side (-D1 side) of the first portion 13 in the first direction (D1 direction). At least a portion of the third portion 17 is located between the first portion 13 and the second portion 15 in the D1 direction. The second portion 15 is thicker than the first portion 13 at least on the first side (both sides in this embodiment. In the description of this embodiment, the +D3 side is taken as an example of the first side) in the thickness direction (D3 direction). The excitation electrode 7 is located in the first portion 13. The extraction electrode 9 is extracted from the excitation electrode 7. The connection electrode 11 is connected to the extraction electrode 9, and is located at the second portion 15. In a first cross section (D1-D3 cross section) parallel to the D1 and D3 directions, a first surface (upper surface 17a) of the third portion 17 facing the +D3 side has (at least one) peak PK at a position away from the first portion 13 and the second portion 15.

[0173] From another perspective, the piezoelectric device (crystal device 101) according to this embodiment includes the crystal element 1 as described above, and a package 103 in which the crystal element 1 is mounted.

[0174] Therefore, for example, as described above, vibration transmitted from first portion 13 to second portion 15 is reduced, and ultimately, the likelihood of noise occurring in the electrical signal flowing through connection electrode 11 located at second portion 15 is reduced.

[0175] In the D1-D3 cross section, the upper surface 17a of the third portion 17 may have a curve that includes a peak PK.

[0176] In this case, for example, the orientation of the upper surface 17a changes at multiple positions on the curve. As a result, for example, compared to the aspect in which the peak PK is formed by a corner where two straight lines intersect (FIG. 9(a)), the vibration transmitted from the first portion 13 to the second portion 15 is reflected in various directions by the upper surface 17a and dispersed. As a result, the probability that a large vibration is transmitted to the second portion 15 is reduced. Also, for example, compared to the aspect in which the peak PK is formed by a corner, the probability that the conductor pattern 5 (the connection electrode 11 and / or the extraction electrode 9 in this embodiment) overlapping the third portion 17 becomes thin at the peak PK is reduced. That is, the reliability of the electrical connection is improved.

[0177] In the D1-D3 cross section, the upper surface 17a of the third portion 17 may have a recess 17r on the side of the second portion 15 of the peak PK (-D1 side).

[0178] In this case, for example, compared to an embodiment (FIG. 9(c)) in which the recess 17r is not located on the second portion 15 side of the peak PK, the proportion of the space (area where no crystal is arranged) between the peak PK (or from another point of view, the protrusion 17p) and the second portion 15 is increased. As a result, the effect of the vibration transmitted from the first portion 13 to the protrusion 17p being trapped without being transmitted to the second portion 15 is improved.

[0179] The recess 17r may have a portion located on the -D3 side of the peak PK in the D3 direction (the side opposite to the side where the second portion 15 is thicker than the first portion 13).

[0180] In this case, for example, compared to an embodiment in which the recess 17r does not have a portion located on the -D3 side of the peak PK in the D3 direction (FIG. 9(b)), the ratio of the space between the peak PK and the second portion 15 becomes larger. As a result, the effect of confining the vibration transmitted from the first portion 13 to the protrusion 17p is further improved.

[0181] The peak PK may be located in the D3 direction between the position of the surface (upper surface) of the first portion 13 facing the +D3 side and the position of the surface (upper surface) of the second portion 15 facing the +D3 side.

[0182] In this case, the peak PK is less likely to come into contact with other members than in a case where the peak PK is located at the same height as the upper surface of the second portion 15 (FIG. 9(a)). As a result, the likelihood of the peak PK being chipped is reduced. Also, for example, when the quartz crystal plate 3 is viewed from the +D3 side and the -D1 side, an invisible area (hereinafter, such an area may be referred to as a "shadow") is less likely to occur in the portion of the upper surface of the first portion 13 on the third portion 17 side and / or the portion of the protrusion 17p on the first portion 13 side. As a result, for example, in the manufacturing process, when a material to become the conductor pattern 5 is deposited from the +D3 side and the -D1 side, the likelihood of a problem occurring in which a non-conductor arrangement area (unintended) is formed in the shadow area is reduced. In other words, the reliability of conduction is improved.

[0183] In the D1-D3 cross section, the upper surface 17a of the third portion 17 may have a plurality of peaks PK at positions away from the first portion 13 and the second portion 15.

[0184] In this case, for example, at least some of the various effects described above are improved. For example, the effect of reducing vibration transmitted from the first portion 13 to the second portion 15 is improved.

[0185] The multiple peaks PK may be located on the +D3 side as they are closer to the second site 15 in the D1 direction.

[0186] In this case, since the peak PK on the first portion 13 side is lower than in the case where the multiple peaks PK are located at the same height (see lines Lv1 and Lv2 in FIG. 7), the above-mentioned effect that a shadow area is less likely to occur in the manufacturing process is achieved. On the other hand, since the multiple peaks PK are not equally low but the peak PK on the second portion 15 side is relatively high, for example, the strength of the second portion 15 side is improved.

[0187] At least one of the extraction electrode 9 and the connection electrode 11 (the connection electrode 11 in the illustrated example) may have a portion that overlaps with the peak PK in the D1-D3 cross section.

[0188] In this case, for example, in an embodiment in which the upper surface 17a has a curve Lp including the peak PK, the likelihood that the conductor pattern 5 will be thin at the peak PK is reduced, as described above. Also, for example, in an embodiment in which the peak PK is lower than the upper surface of the second portion 15 and / or in which the multiple peaks PK are higher toward the second portion 15, as described above, a shaded region is unlikely to be generated in the manufacturing process, and the likelihood that a non-placement region (unintended region) of the conductor pattern 5 will be configured is reduced.

[0189] The piezoelectric body (quartz crystal plate 3) may be an AT-cut quartz crystal plate 3. The D1 direction (the direction in which the second portion 15 and the third portion 17 (peak PK) are located relative to the first portion 13) may be parallel to the X-axis.

[0190] In this case, for example, compared to an embodiment in which the D1 direction is parallel to the Z' axis (this embodiment is also included in the technology according to the present disclosure), the slope of the protrusion 17p generated by etching is more likely to be inclined with respect to the D3 direction. As a result, for example, the effect of preventing a shadow from being generated in the first portion 13 during the manufacturing process is improved. Note that, from the viewpoint of the effect of reducing unintended vibrations by the protrusion 17p, the embodiment in which the D1 direction is parallel to the Z' axis may be selected.

[0191] In the first embodiment, the quartz crystal elements 1 and 1I are each an example of a piezoelectric element. The quartz crystal device 101 is an example of a piezoelectric device. The quartz crystal blanks 3, 3E, 3F, 3G, 3H and 3I are each an example of a piezoelectric body. The D1 direction is an example of the first direction. The -D1 side is an example of one side of the first direction. The D3 direction is an example of the thickness direction. The +D3 side is an example of the first side in the thickness direction. The D1-D3 cross section is an example of the first cross section. The upper surface 17a of the third portion 17 is an example of the first surface.

[0192] <Second embodiment> FIG. 13 is a perspective view showing a crystal element 201 according to the second embodiment.

[0193] The crystal element 201 has, for example, a configuration that is 180° rotationally symmetric with respect to a center line (not shown) parallel to the D1 direction. Therefore, the perspective view seen from the -D3 side is the same as that of FIG. 13. However, the crystal element 201 does not have to have a configuration that is 180° rotationally symmetric. In the following description, as in the description of the first embodiment, only the portion of the crystal element 201 on the +D3 side may be mentioned. In that case, the description may be applied to the portion on the -D3 side unless a contradiction occurs.

[0194] In this embodiment, as in the first embodiment, the portion where the excitation electrode 7 is located is referred to as the first portion, the portion where the connection electrode is located is referred to as the second portion, and the portion therebetween is referred to as the third portion. In the crystal plate 203 of this embodiment, the peak PK is located on the upper surface 217a of the third portion 217, as shown in Fig. 14, which will be described later. This provides, for example, the same effects as those described in the first embodiment.

[0195] However, while in the first embodiment, the second portion 15 is thicker than the first portion 13, in this embodiment, the first portion 213 is thicker than the second portion 215. That is, the positional relationship between the thick and thin portions of the quartz crystal plate and the excitation electrodes 7 and connection electrodes 11 is reversed between the first and second embodiments. Specifically, it is as follows.

[0196] The quartz crystal element 201 is of a so-called mesa type. That is, the quartz crystal plate 203 has a mesa portion where the excitation electrode 7 is located, and an outer periphery portion that surrounds the mesa portion in a plan view and is thinner than the mesa portion. The mesa portion is the first portion 213 (or the first portion 213 and the third portion 217), and the outer periphery portion is the second portion 215.

[0197] The configuration of the quartz crystal element 201 may be basically the same as that of a known mesa-type quartz crystal element, except that the third portion 217 is located between the first portion 213 and the second portion 215. From another perspective, the present embodiment may be applied to various mesa-type quartz crystal elements.

[0198] For example, the planar shape of the first portion 213 (mesa portion), the planar shape of the second portion 215 (periphery), and the planar shape of the excitation electrode 7 may be various shapes such as rectangular (as shown in the example), circular, elliptical, etc., and the relationship (similar or not) between the planar shapes of these three portions (members) is also arbitrary. In addition, various dimensions of the first portion 213, the second portion 215, and the excitation electrode 7 are also arbitrary.

[0199] Also, for example, the outer edge of the excitation electrode 7 (taking the +D3 side as an example as described above) may be located on the upper surface of the first portion 213 (including the boundary with the third portion 17) (in the illustrated example), or may be located on the upper surface 217a of the third portion 217 (excluding the boundaries with the first portion 213 and the second portion 215), or may be located on the upper surface of the second portion 215 (including the boundary with the third portion 217). Also, such a positional relationship may be different between the edge portions on both sides in the D1 direction and the edge portions on both sides in the D2 direction.

[0200] This is the opposite of the explanation above, but the extraction electrode 9 (+D3 side) may extend across the upper surface of the first portion 213, the upper surface of the third portion 217, and the upper surface of the second portion 215, or it may not be located on the upper surface of the first portion 213 but extend across the upper surface of the third portion 217 and the upper surface of the second portion 215, or it may be located only on the upper surface of the second portion 215.

[0201] Fig. 14 is a schematic diagram showing the surface shape of the quartz crystal plate 203 in region XIV of Fig. 13. The left side of Fig. 14 is a plan view. The right side of Fig. 14 is a cross-sectional view taken along line XIVa-XIVa in the plan view on the left side of Fig. 14.

[0202] 14, the upper surface 217a of the third portion 217 has at least one (one in the illustrated example) peak PK (convex portion 217p from another point of view) in the D1-D3 cross section. In the illustrated example, a concave portion 217r is located on the first portion 213 side of the peak PK.

[0203] As described above, the explanations of the first embodiment and other examples may be incorporated into this embodiment as long as no contradictions or the like arise. Therefore, for example, the number of peaks PK is arbitrary, and the shape of the line including the peaks PK (whether it is curved or not, etc.) is also arbitrary. When incorporating, in terms of thick and thin parts, the term "first region 13" is replaced with the term "second region 215," and the term "second region 15" is replaced with the term "first region 213." In addition, the terms "+D1 side" and "-D1 side" are also replaced appropriately.

[0204] FIG. 14 illustrates the shape of a portion of the upper surface 17a of the third portion 217 located on the -D1 side with respect to the first portion 213. As can be understood from the explanation of the other examples in FIG. 11(b), the range in which the peak PK is located in the direction along the outer edge of the first portion 213 is arbitrary. For example, in a mode in which the outer edge of the first portion 213 has a shape (e.g., rectangular) that can be conceptualized as four edges (four sides) that intersect with each other and the third portion 217 is located along the four edges, the peak PK may be located on one side, two sides, three sides, or four sides of the third portion 217. In addition, the side of the third portion 217 on which the peak PK is located may be the side on the side (-D1 side) on which the connection electrode 11 is located with respect to the excitation electrode 7, or may be another side, and may also be the side on which the conductor pattern 5 (the extraction electrode 9 and / or the excitation electrode 7) is located, or may be another side.

[0205] As described above, in this embodiment, the piezoelectric element (quartz crystal element 201) has a piezoelectric body (quartz crystal blank 203), an excitation electrode 7, an extraction electrode 9, and a connection electrode 11. The quartz crystal blank 203 has a first portion 213, a second portion 215, and a third portion 217. In a plan view, at least a portion of the second portion 215 is located on one side (-D1 side) of the first direction (D1 direction) relative to the first portion 213. At least a portion of the third portion 217 is located between the first portion 213 and the second portion 215 in the D1 direction. The first portion 213 is thicker than the second portion 215 on at least a first side (both sides in this embodiment. In the description of this embodiment, the +D3 side is taken as an example of the first side) in the thickness direction (D3 direction). The excitation electrode 7 is located in the first portion 213. The extraction electrode 9 is extracted from the excitation electrode 7. The connection electrode 11 is connected to the extraction electrode 9 and is located at the second portion 215. In a first cross section (D1-D3 cross section) parallel to the D1 and D3 directions, the first surface (upper surface 217a) of the third portion 17 facing the +D3 side has (at least one) peak PK and a recess 17r. The peak PK is away from the first portion 213 and the second portion 215. The recess 17r is located on the first portion 213 side of the peak PK, and has a portion located on the -D3 side of the peak PK in the D3 direction (opposite the side where the first portion 213 is thicker than the second portion 215).

[0206] Therefore, for example, the same effects as those of the first embodiment are achieved. For example, vibration transmitted from the first portion 213 to the second portion 215 is reduced. This is expected to improve the effect of trapping vibration energy in the mesa portion (first portion 213). In addition, for example, the probability of a shadowed region occurring during the manufacturing process is reduced, improving the reliability of conduction of the conductor pattern 5 (for example, the extraction electrode 9).

[0207] In the second embodiment, the quartz crystal element 201 is an example of a piezoelectric element, and the quartz crystal plate 203 is an example of a piezoelectric body.

[0208] <Third embodiment> FIG. 15 is a perspective view showing a wafer 351 (an example of a piezoelectric wafer) according to the third embodiment.

[0209] The wafer 351, like the wafer 51 in the first embodiment, has a plurality of element regions 303 that become a plurality of quartz crystal plates 3 by etching. Note that, for convenience, the symbols in the first embodiment may be used here, but the wafer 351 may be used for producing quartz crystal elements of other aspects according to the present disclosure. Furthermore, the wafer 351 may be used for producing quartz crystal elements other than the quartz crystal elements according to the present disclosure.

[0210] The term wafer 351 may refer to a wafer at any stage before the crystal elements 1 are diced into individual crystal elements. FIG. 15 may be taken as a schematic diagram of the wafer 351 at any stage described above. The surface shape of the wafer 351 described later (surface shape shown in FIG. 15 and FIG. 16) may be realized at any stage. However, in the following description, the description and expression may be made on the assumption that the surface shape of the wafer 351 is realized before etching through the first mask and the second mask described in the first embodiment. Note that, in a state where etching through the first mask and the second mask is not performed, each element region 303 is connected to other parts of the wafer 351 (for example, the adjacent element region 303) over its entire circumference.

[0211] In plan view, the wafer 351 has an inner periphery 313, an outer periphery 315 surrounding the inner periphery 313, and an intermediate portion 317 located therebetween. The inner periphery 313 is a portion having a plurality of element regions 303. The outer periphery 315 is thicker on the +D3 side than the inner periphery 313. Unlike the illustrated example, the outer periphery 315 may be thicker on both sides in the D3 direction than the inner periphery 313. The intermediate portion 317 has an upper surface 317a facing the side (+D3 side) where the outer periphery 315 is thicker than the inner periphery 313. The upper surface 317a is inclined so that, for example, the outer periphery 315 is positioned closer to the +D3 side as a whole.

[0212] Fig. 16 is a schematic diagram showing the surface shape of the wafer 351 in region XVI in Fig. 15. The left side of Fig. 16 is a plan view. The right side of Fig. 16 is a cross-sectional view taken along line XVIa-XVIa in the plan view on the left side of Fig. 16.

[0213] As shown in this figure, the top surface 317a of the intermediate portion 317 of the wafer 351 has a shape having a peak PK (or, from another point of view, a convex portion 317p), similar to the top surface 17a of the third portion 17 of the quartz crystal plate 3. This provides, for example, effects that are the same as or similar to at least some of the various effects described in the first embodiment, and / or other effects.

[0214] As described above, the explanations of the first embodiment, the other examples, and the second embodiment may be incorporated into this embodiment, unless there is a contradiction, etc. When incorporating, for example, the terms first portion 13, second portion 15, and third portion 17 may be replaced with the terms inner peripheral portion 313, outer peripheral portion 315, and middle portion 317. In other words, the incorporation may be performed by associating one quartz crystal plate 3 with one wafer 351.

[0215] Therefore, for example, the number of peaks PK is arbitrary, and the shape of the line including the peaks PK (whether it is curved or not, etc.) is also arbitrary. Also, as can be seen from other examples in Fig. 10(a) to Fig. 11(b), the range of the outer circumferential portion 315 and the range in which the peaks PK are located in the direction along the edge of the inner circumferential portion 313 are arbitrary.

[0216] In the illustrated example, the peak PK is located between the position of the upper surface of the inner circumference portion 313 and the position of the upper surface of the outer circumference portion 315 in the D3 direction. Furthermore, the upper surface 317a of the intermediate portion 317 has a recess 317r on the outer circumference portion 315 side of the peak PK. The recess 317r is lower than the peak PK in the D3 direction (located on the -D3 side). In the example of FIG. 15, the wafer 351 is rectangular. However, the wafer 351 may have another shape (for example, a circular shape). The same applies to the shape of the inner circumference portion 313, etc.

[0217] The method for producing the wafer 351 may be roughly the same as a known production method. However, before etching the outer shape of the quartz crystal plate 3 through the first mask (see the description of the first embodiment), the inner periphery 313 is made thinner than the outer periphery 315, and a peak PK is formed in the middle portion 317. This method may be the same as the method in the first embodiment in which the first portion 13 is made thinner than the second portion 15 and a peak PK is formed in the third portion 17. For example, etching may be performed through a mask that overlaps the regions that will become the outer periphery 315 and the middle portion 317 and has an opening in a portion that overlaps the region that will become the middle portion 317.

[0218] As described above, in this embodiment, the piezoelectric wafer (wafer 351) has an inner circumference portion 313, an outer circumference portion 315, and an intermediate portion 317. The inner circumference portion 313 has a plurality of regions (element regions 303) constituting a plurality of piezoelectric elements (crystal elements 1). The outer circumference portion 315 has a portion located on one side (-D1 side) of the first direction (D1 direction) with respect to the inner circumference portion 313 in a plan view. The intermediate portion 317 has a portion located between the inner circumference portion 313 and the outer circumference portion 315 in the D1 direction. The outer circumference portion 315 is thicker at least toward the first side (+D3 side) in the thickness direction (D3 direction) with respect to the inner circumference portion 313. In a first cross section (D1-D3 cross section) parallel to the D1 direction and the D3 direction, the first surface (upper surface 317a) of the intermediate portion 317 facing the +D3 side has a peak PK at a position away from the inner circumference portion 313 and the outer circumference portion 315. The peak PK is located between the position of the upper surface of the inner circumferential portion 313 and the position of the upper surface of the outer circumferential portion 315 in the D3 direction.

[0219] Therefore, first, since the outer peripheral portion 315 is relatively thick, the strength of the wafer 351 is ensured, and the handleability of the wafer 351 is improved. The thickness of the inner peripheral portion 313 must ultimately match the thickness of the quartz crystal plate 3, and cannot be kept relatively thick. Secondly, since the middle portion 317 has a peak PK lower than the upper surface of the outer peripheral portion 315, as can be understood from the description of the first embodiment, the possibility of a shadow being generated on the outer peripheral portion 315 side of the inner peripheral portion 313 and / or the middle portion 317 is reduced. As a result, for example, the possibility of a non-disposition region (unintended) of the film being generated is reduced. Examples of the film include the above-mentioned first mask, second mask, other masks (for example, masks for forming the conductor pattern 5), and the conductor pattern 5. When the non-disposition regions (unintended) of the first mask and the second mask are configured, there is a possibility that an unintended hole is formed in the non-disposition region, but the possibility of such an inconvenience is reduced.

[0220] The technology according to the present disclosure is not limited to the above embodiments and other examples, and may be implemented in various forms.

[0221] The piezoelectric body is not limited to quartz. For example, the piezoelectric body may be another single crystal or may be made of polycrystal (for example, ceramic). Note that quartz to which an appropriate dopant is added may be considered as a type of quartz.

[0222] The piezoelectric element is not limited to one that generates an oscillation signal. For example, the piezoelectric element may be a piezoelectric vibration type gyro sensor. The piezoelectric body is not limited to a plate-shaped one (piezoelectric plate). For example, the piezoelectric body may be a shape having a base and one or more arms extending from the base (for example, a tuning fork type). For example, the arms may be a first portion, the base may be a second portion that is thicker than the first portion, and a third portion may be located therebetween. As can be seen from this example of the shape of the piezoelectric body, the arrangement of the excitation electrodes, extraction electrodes (wiring), and connection electrodes may also be arbitrary.

[0223] In the embodiment, the piezoelectric element is exemplified as being supported in a cantilever shape by two conductive bonding materials. From another point of view, the two connection electrodes are arranged side by side along one end (one side) of the underside of the piezoelectric body. However, the mounting form of the piezoelectric element may be other than that, and the position and shape of the connection electrodes may be different from that of the embodiment. For example, the piezoelectric element may be supported at both ends, and the connection electrodes may be located at different ends of the piezoelectric plate (in different directions from another point of view). In addition, at least one of the two connection electrodes may be electrically connected by a bonding wire. The two connection electrodes may face each other in the thickness direction of the piezoelectric body.

[0224] The third portion may have a convex portion, a concave portion, and / or a through hole in addition to the peak PK, the convex portion 17p having the peak, and the concave portion 17r appearing with the convex portion 17p described in the embodiment. For example, in the first embodiment, a concave portion having a bottom surface flush with the upper surface of the first portion 13 may be formed across the first portion 13 and the second portion 15. Such a concave portion contributes to, for example, reducing a shadowed area. In addition, the through hole may contribute to, for example, the arrangement of a conductor (a part of the conductor pattern 5) that conducts electricity between the front and back of the crystal element, and / or contribute to reducing mechanical interference between the first portion 13 and the second portion 15.

[0225] In the description of the embodiments, for convenience, the reduction of unintended vibration transmission is exemplified as a problem (or an effect in another respect). However, the technology according to the present disclosure may be used in a manner in which such a problem is not necessarily solved.

[0226] From the present disclosure, technical ideas that do not require the configurations described as the main features in the description of the embodiments may be extracted. For example, the curve including the peak may be applied to the outer edge of the quartz crystal plate, instead of the third portion between the first and second portions.

[0227] The following concepts can be extracted from this disclosure. (Concept 1) a piezoelectric body having, in a plan view, a first portion, a second portion at least a portion of which is located on one side of the first portion in a first direction, and a third portion at least a portion of which is located between the first portion and the second portion in the first direction, the second portion being thicker than the first portion at least toward the first side in a thickness direction; an excitation electrode located at the first portion; an extraction electrode that is extracted from the excitation electrode; a connection electrode connected to the extraction electrode and located at the second portion; It has In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side has a peak at a position away from the first portion and the second portion. Piezoelectric element. (Concept 2) In the first cross section, the first surface has a curve including the peak. 2. A piezoelectric element as described in concept 1. (Concept 3) In the first cross section, the first surface has a recess on the second portion side of the peak. 3. The piezoelectric element according to claim 1 or 2. (Concept 4) The recess has a portion located on the opposite side to the first side relative to the peak in the thickness direction. 4. The piezoelectric element of claim 3. (Concept 5) The peak is located between a position of a surface of the first portion facing the first side and a position of a surface of the second portion facing the first side in the thickness direction. A piezoelectric element according to any one of Concepts 1 to 4. (Concept 6) In the first cross section, the first surface has a plurality of the peaks at positions away from the first portion and the second portion. A piezoelectric element according to any one of concepts 1 to 5. (Concept 7) The plurality of peaks are located closer to the second portion in the first direction to the first side in the thickness direction. 7. The piezoelectric element of claim 6. (Concept 8) At least one of the extraction electrode and the connection electrode has a portion that overlaps with the peak in the first cross section. 8. The piezoelectric element according to claim 2, 5 or 7. (Concept 9) The piezoelectric body is an AT-cut quartz crystal plate, The first direction is parallel to the X-axis. A piezoelectric element according to any one of concepts 1 to 8. (Concept 10) a piezoelectric body including, in a plan view, a first portion, a second portion at least a portion of which is located on one side of the first portion in a first direction, and a third portion at least a portion of which is located between the first portion and the second portion in the first direction, the first portion being thicker than the second portion at least toward the first side in a thickness direction; an excitation electrode located at the first portion; an extraction electrode that is extracted from the excitation electrode; a connection electrode connected to the extraction electrode and located at the second portion; Equipped with In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side is a peak that is distant from the first site and the second site; a recess having a portion located on the first portion side of the peak and located on the opposite side to the first side relative to the peak in the thickness direction; Piezoelectric element. (Concept 11) A piezoelectric element according to any one of concepts 1 to 10; a package in which the piezoelectric element is mounted; A piezoelectric device having a (Concept 12) an inner periphery having a plurality of regions each forming a plurality of piezoelectric elements; an outer circumferential portion having a portion located on one side in a first direction with respect to the inner circumferential portion in a plan view; an intermediate portion having a portion located between the outer circumferential portion and the inner circumferential portion in the first direction; The outer circumferential portion is thicker than the inner circumferential portion at least toward a first side in a thickness direction, In a first cross section along the first direction and the thickness direction, a first surface of the intermediate portion facing the first side has a peak at a position away from the outer circumferential portion and the inner circumferential portion, The peak is located between the position of the first side surface of the inner circumferential portion and the position of the first side surface of the outer circumferential portion in the thickness direction. Piezoelectric wafer. [Explanation of symbols]

[0228] 1...quartz element (piezoelectric element), 3...quartz crystal plate (piezoelectric body), 7...excitation electrode, 9...extraction electrode, 11...connection electrode, 13...first part (of the quartz crystal plate), 15...second part (of the quartz crystal plate), 17...third part, 17a...top surface (first face) of third part, 101...quartz crystal device (piezoelectric device), PK...peak (of the top surface of the third part).

Claims

1. a piezoelectric body having, in a plan view, a first portion, a second portion at least a portion of which is located on one side of the first portion in a first direction, and a third portion at least a portion of which is located between the first portion and the second portion in the first direction, the second portion being thicker than the first portion at least toward the first side in a thickness direction; an excitation electrode located at the first portion; an extraction electrode that is extracted from the excitation electrode; a connection electrode connected to the extraction electrode and located at the second portion; It has In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side is having a peak at a position away from the first portion and the second portion; and A curve including the peak Piezoelectric element.

2. In the first cross section, the first surface has a recess on the second portion side of the peak. The piezoelectric element according to claim 1 .

3. The recess has a portion located on the opposite side to the first side relative to the peak in the thickness direction. The piezoelectric element according to claim 2 .

4. The peak is located between a position of a surface of the first portion facing the first side and a position of a surface of the second portion facing the first side in the thickness direction. The piezoelectric element according to claim 1 .

5. In the first cross section, the first surface has a plurality of the peaks at positions away from the first portion and the second portion. The piezoelectric element according to claim 1 .

6. A piezoelectric body having, in a plan view, a first portion, a second portion at least a portion of which is located on one side of the first portion in a first direction, and a third portion at least a portion of which is located between the first portion and the second portion in the first direction, and the second portion is thicker than the first portion toward at least the first side in the thickness direction; an excitation electrode located at the first portion; an extraction electrode that is extracted from the excitation electrode; a connection electrode connected to the extraction electrode and located at the second portion; It has In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side has a plurality of peaks at positions away from the first portion and the second portion, The plurality of peaks are located closer to the second portion in the first direction to the first side in the thickness direction. Piezoelectric element.

7. At least one of the extraction electrode and the connection electrode has a portion that overlaps the peak in the first cross section. The piezoelectric element according to claim 1 .

8. The piezoelectric body is an AT-cut quartz crystal plate, The first direction is parallel to the X-axis. The piezoelectric element according to claim 1 .

9. a piezoelectric body including, in a plan view, a first portion, a second portion at least a portion of which is located on one side of the first portion in a first direction, and a third portion at least a portion of which is located between the first portion and the second portion in the first direction, the first portion being thicker than the second portion at least toward the first side in a thickness direction; an excitation electrode located at the first portion; an extraction electrode that is extracted from the excitation electrode; a connection electrode connected to the extraction electrode and located at the second portion; Equipped with In a first cross section along the first direction and the thickness direction, a first surface of the third portion facing the first side is a peak spaced apart from the first and second regions; A curve including the peak; a recess having a portion located on the first portion side of the peak and located on an opposite side to the first side relative to the peak in the thickness direction; Piezoelectric element.

10. A piezoelectric element according to any one of claims 1 to 9, a package in which the piezoelectric element is mounted; A piezoelectric device having a

11. an inner periphery having a plurality of regions each forming a plurality of piezoelectric elements; an outer circumferential portion having a portion located on one side in a first direction with respect to the inner circumferential portion in a plan view; an intermediate portion having a portion located between the outer circumferential portion and the inner circumferential portion in the first direction, The outer circumferential portion is thicker than the inner circumferential portion at least toward a first side in a thickness direction, In a first cross section along the first direction and the thickness direction, a first surface of the intermediate portion facing the first side has a peak at a position away from the outer circumferential portion and the inner circumferential portion, The peak is located between the position of the first side surface of the inner circumferential portion and the position of the first side surface of the outer circumferential portion in the thickness direction. Piezoelectric wafer.

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