piezoelectric device

Abstract

In a piezoelectric device (100), a connecting portion (130) connects a pair of beam portions (120) adjacent to each other among a plurality of beam portions (120) to each other. The connecting portion (130) is connected to one of the pair of beam portions (120) at a first end portion. The connecting portion (130) is connected to the other of the pair of beam portions (120) at a second end portion. The second end portion is opposite to the first end portion in a direction in which the pair of beam portions (120) are arranged. The second connecting portion is located at a position along the first connecting portion. The connecting portion (130) has only one first end portion. The connecting portion (130) has only one second end portion. The first end portion and the second end portion are located at positions closer to respective top end portions (122) of the pair of beam portions (120) than to fixed end portions (121), respectively.

Description

Technical Field

[0001] This invention relates to a piezoelectric device. Background Technology

[0002] As documents disclosing the structure of a piezoelectric device, there are U.S. Patent Application Publication No. 2019 / 0110132 (Patent Document 1) and Japanese Patent No. 5491080 (Patent Document 2). The piezoelectric device described in Patent Document 1 is a sound transducer comprising multiple plates and multiple springs. The sound transducer has gaps that control its geometry. The multiple springs are gap-reducing springs that connect two adjacent plates. Spring arms include portions surrounding etched portions of the plates. The adjacent plates can encompass a distance from the top of the plates to the center of the springs.

[0003] Patent Document 2 describes a piezoelectric device, which is a microphone, comprising a support frame, a first vibrating plate, a second vibrating plate, and a connecting body. One end of both the first and second vibrating plates is elastically supported by the support frame. The other end of the first vibrating plate is positioned opposite to the other end of the second vibrating plate. The other ends of the first and second vibrating plates are connected by the connecting body. The connecting body is designed to be displaceable relative to the other ends of the first and second vibrating plates, thus achieving parallel or tilted vibration in response to the vibration of either the first or second vibrating plate. The connecting body is a thin, flat plate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: U.S. Patent Application Publication No. 2019 / 0110132

[0007] Patent Document 2: Japanese Patent No. 5491080 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Patent Document 1 discloses a piezoelectric device that includes a connecting portion that connects adjacent beams of a plurality of beams, such as a vibrating plate or plate. This reduces the vibration deviation of each of the multiple beams. In the piezoelectric device disclosed in Patent Document 2, each vibrating plate, which is a beam, is connected to each other by a connecting body, which is a connecting portion. This allows each beam to vibrate with a phase difference. However, in these conventional piezoelectric devices, stress is generated in the direction in which the connecting portion pulls on the beam, sometimes causing the connection between the beams, achieved by the connecting portion, to become too rigid. If the connection becomes too rigid, each beam becomes stiff, and the resonant frequency of each beam's vibration increases.

[0010] The present invention was made in view of the above-mentioned problems, and its object is to provide a piezoelectric device that can reduce the vibration deviation of the multiple beams while suppressing the resonant frequency of each beam.

[0011] Solution for solving the problem

[0012] The piezoelectric device according to the present invention includes a base, a plurality of beams, and a connecting portion. Each of the plurality of beams has a fixed end and a top end. The fixed end is connected to the base. The top end is located on the side opposite to the fixed end. Each of the plurality of beams extends from the fixed end toward the top end. Each of the plurality of beams is a piezoelectric vibrating portion comprising multiple layers. The connecting portion connects a pair of adjacent beams to each other. A first slit and a second slit are provided between the pair of beams. The first slit is formed by a portion of a pair of adjacent end edges of the pair of beams. The second slit is formed at a different location from the first slit by another portion of a pair of adjacent end edges of the pair of beams. The connecting portion is located at least between the first slit and the second slit. The connecting portion has a first end, a second end, a bridging portion, a first connecting portion, and a second connecting portion. The connecting portion is connected to one of the pair of beams at the first end. The connecting portion is connected to the other of the pair of beams at the second end. The second end is opposite to the first end in the direction in which the pair of beams are arranged. The bridging section is folded back between a pair of beams and is provided for connection. A first connecting section connects to the portion of the bridging section located on one side of the pair of beams. A second connecting section connects to the portion of the bridging section located on the other side of the pair of beams. The second connecting section is located along the first connecting section. The connecting section has only one first end. The connecting section has only one second end. The first and second ends are located closer to the top ends of the respective pair of beams than to the fixed ends.

[0013] The effects of the invention

[0014] According to the present invention, it is possible to reduce the vibration deviation of multiple beams while increasing the resonant frequency when suppressing the vibration of each beam. Attached Figure Description

[0015] Figure 1 This is a top view of the piezoelectric device according to Embodiment 1 of the present invention.

[0016] Figure 2 Observe from the direction of the arrow on line II-II Figure 1 The cross-sectional view obtained from the piezoelectric device.

[0017] Figure 3 It is an enlarged representation Figure 1 A partial top view of part III.

[0018] Figure 4 This is a partial top view of the piezoelectric device of the first variation of Embodiment 1 of the present invention.

[0019] Figure 5 This is a top view of the piezoelectric device of the second variation of Embodiment 1 of the present invention.

[0020] Figure 6 Observe from the direction of the arrow on line VI-VI Figure 5 A partial cross-sectional view obtained from the piezoelectric device shown.

[0021] Figure 7 This is a top view of the piezoelectric device of the third variation of Embodiment 1 of the present invention.

[0022] Figure 8 Observe from the direction of the arrow on line VIII-VIII Figure 7 A partial cross-sectional view obtained from the piezoelectric device shown.

[0023] Figure 9 Observe from the direction of the arrow on line IX-IX Figure 7 A partial cross-sectional view obtained from the piezoelectric device shown.

[0024] Figure 10 This is a partial cross-sectional view schematically showing the beam portion of the piezoelectric device according to Embodiment 1 of the present invention.

[0025] Figure 11 This is a partial cross-sectional view schematically showing the beam portion of the piezoelectric device according to Embodiment 1 of the present invention during operation.

[0026] Figure 12 This is a three-dimensional diagram illustrating the state of vibration of the piezoelectric device according to Embodiment 1 of the present invention in a basic vibration mode.

[0027] Figure 13 This is a cross-sectional view showing the state in which a second electrode layer is provided on a piezoelectric single crystal substrate in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0028] Figure 14 This is a cross-sectional view showing the state in which the first support portion is provided during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0029] Figure 15 This is a cross-sectional view showing the state in which the laminate is joined to the first support portion during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0030] Figure 16 This is a cross-sectional view showing the state in which a piezoelectric single crystal substrate is cut to form a piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0031] Figure 17 This is a cross-sectional view showing the state in which the first electrode layer is provided in the piezoelectric body layer during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0032] Figure 18 This is a cross-sectional view showing the state in which the groove and recess are provided in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0033] Figure 19 This is a partial cross-sectional view showing the state in which the first connecting electrode layer and the second connecting electrode layer are provided in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0034] Figure 20 This is a top view of the piezoelectric device according to Embodiment 2 of the present invention.

[0035] Figure 21 This is a top view of the piezoelectric device of the first variation of Embodiment 2 of the present invention.

[0036] Figure 22 Observe from the direction of the arrow in line XII-XII Figure 21 A partial cross-sectional view obtained from the piezoelectric device shown.

[0037] Figure 23 This is a top view of the piezoelectric device of the first variation of Embodiment 3 of the present invention.

[0038] Figure 24 Observe from the direction of the arrow in line XXIV-XXIV. Figure 23 A partial cross-sectional view of the piezoelectric device shown.

[0039] Figure 25 This is a top view of the piezoelectric device according to Embodiment 3 of the present invention.

[0040] Figure 26 This is a top view of the piezoelectric device according to Embodiment 4 of the present invention.

[0041] Figure 27 Observe from the direction of the arrow in line XXVII-XXVII. Figure 26 The cross-sectional view obtained from the piezoelectric device.

[0042] Figure 28 This is a partial top view showing the structure of the connection portion of the piezoelectric device according to Embodiment 4 of the present invention.

[0043] Figure 29 It is a chart representing the results of the simulation analysis.

[0044] Figure 30 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the first modified example of Embodiment 4 of the present invention.

[0045] Figure 31 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the second variation of Embodiment 4 of the present invention.

[0046] Figure 32 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the third variation of Embodiment 4 of the present invention.

[0047] Figure 33 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the fourth variation of Embodiment 4 of the present invention.

[0048] Figure 34 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the fifth variation of Embodiment 4 of the present invention.

[0049] Figure 35 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the sixth variation of Embodiment 4 of the present invention.

[0050] Figure 36 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the seventh variation of Embodiment 4 of the present invention. Detailed Implementation

[0051] Hereinafter, piezoelectric devices according to various embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the embodiments, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0052] (Implementation Method 1)

[0053] Figure 1 This is a top view of the piezoelectric device according to Embodiment 1 of the present invention. Figure 2 Observe from the direction of the arrow on line II-II Figure 1 The cross-sectional view obtained from the piezoelectric device. Figure 3 It is an enlarged representation Figure 1 A partial top view of part III.

[0054] like Figures 1-3 As shown, the piezoelectric device 100 of Embodiment 1 of the present invention includes a base 110, a plurality of beam portions 120, and a connecting portion 130. In the piezoelectric device 100 of this embodiment, the plurality of beam portions 120 are each capable of bending and vibrating, and can be used as an ultrasonic transducer.

[0055] like Figure 1As shown, the base 110 is connected to the fixed ends 121 of each of the plurality of beam portions 120. The base 110 has an annular shape when viewed from the stacking direction of the plurality of layers (described later), specifically, a rectangular annular shape. Furthermore, the shape of the base 110 when viewed from the stacking direction is not particularly limited. The outer peripheral surface of the annular base 110, when viewed from the stacking direction, can also be polygonal or circular, and the inner peripheral surface can also be polygonal or circular.

[0056] like Figure 2 As shown, the multiple beams 120 are piezoelectric vibrating sections comprising multiple layers 10. Furthermore, in Figure 1 The individual layers of the multiple layers 10 are not shown in the diagram. Details regarding the structure of the multiple layers 10 will be described later.

[0057] like Figure 1 As shown, each of the plurality of beam portions 120 has a fixed end portion 121 and a top end portion 122. The fixed end portion 121 is connected to the base portion 110. The fixed ends portion 121 of each of the plurality of beam portions 120 are located in the same imaginary plane. When viewed from the stacking direction, the fixed ends portion 121 of each of the plurality of beam portions 120 are connected to the inner peripheral surface of the annular base portion 110. When viewed from the stacking direction, the fixed ends portion 121 of each of the plurality of beam portions 120 are located adjacent to each other on the inner peripheral surface. In this embodiment, when viewed from the stacking direction, the fixed ends portion 121 of each of the plurality of beam portions 120 are located at positions that correspond one-to-one with multiple sides of the rectangular annular inner peripheral surface of the base portion 110.

[0058] In this embodiment, the top end portion 122 of each of the plurality of beam portions 120 is located near the center of the annular base 110 when viewed from the aforementioned stacking direction. The plurality of beam portions 120 extend from the fixed end portion 121 toward the top end portion 122. That is, in the respective extending direction of the plurality of beam portions 120, the top end portion 122 is located at the end on the side opposite to the fixed end portion 121. In this embodiment, the plurality of beam portions 120 extend along the same imaginary plane when the piezoelectric device 100 is not driven.

[0059] like Figure 1As shown, each of the plurality of beam portions 120 has a pointed top portion 122 when viewed from the aforementioned stacking direction. Specifically, each of the plurality of beam portions 120 has a generally triangular shape when viewed from the aforementioned stacking direction. When the top portion 122 has a pointed shape, the extending direction of each of the plurality of beam portions 120 is the direction connecting the center of the fixed end portion 121 to the top portion 122. In this embodiment, the generally triangular shape is a generally isosceles triangle with the fixed end portion 121 as its base and the vertex located at the top portion 122. That is, in this embodiment, the extending direction of each of the plurality of beam portions 120 refers to the direction connecting the midpoint of the base of the generally isosceles triangle to the vertex of each of the plurality of beam portions 120. In this embodiment, from the viewpoint of facilitating bending vibration, it is preferable that the length of the extending direction of each of the plurality of beam portions 120 is at least 5 times the thickness of each of the plurality of beam portions 120 in the aforementioned stacking direction. Furthermore, in Figure 2 The diagram illustrates the thickness of each of the multiple beam sections 120.

[0060] like Figure 1 and Figure 3 As shown, the connecting portion 130 connects a pair of adjacent beam portions 120 of a plurality of beam portions 120 to each other. The connecting portion 130 has a first end portion 133A and a second end portion 133B. The connecting portion 130 is connected to one of the pair of beam portions 120 at the first end portion 133A. The connecting portion 130 is connected to the other of the pair of beam portions 120 at the second end portion 133B. The second end portion 133B is opposite to the first end portion 133A in the direction in which the pair of beam portions 120 are arranged. In this embodiment, the connecting portion 130 has only one first end portion 133A and only one second end portion 133B.

[0061] The connecting portion 130 includes a bridging portion 131, a first connecting portion 132A, and a second connecting portion 132B. In this embodiment, the bridging portion 131 is provided to connect the pair of beam portions 120 to each other by folding back between them at least via the first connecting portion 132A and the second connecting portion 132B. In this embodiment, the bridging portion 131 in the connecting portion 130 extends in a direction that is aligned with the adjacent first connecting portions 132A and second connecting portions 132B.

[0062] In the connecting portion 130, the first connecting portion 132A is connected to the portion of the bridging portion 131 located on one side of the pair of beam portions 120. In the connecting portion 130, the second connecting portion 132B is connected to the portion of the bridging portion 131 located on the other side of the pair of beam portions 120, and is located along the position of the first connecting portion 132A.

[0063] The first connecting portion 132A extends from one of the pair of beam portions 120 along the second slit 142, starting from the first end portion 133A. The second connecting portion 132B extends from the other of the pair of beam portions 120 along the second slit 142, starting from the second end portion 133B. In this embodiment, the extension lengths of the first connecting portion 132A and the second connecting portion 132B are approximately the same. In this embodiment, the first connecting portion 132A is directly connected to the bridging portion 131 on the side opposite to the side of the first end portion 133A. That is, in this embodiment, the first connecting portion 132A directly connects the bridging portion 131 to one of the pair of beam portions 120 at the first end portion 133A. The second connecting portion 132B is directly connected to the bridging portion 131 on the side opposite to the side of the second end portion 133B. That is, in this embodiment, the second connecting portion 132B directly connects the bridging portion 131 at its second end 133B to another of the pair of beam portions 120. For example... Figure 1 and Figure 3 As shown, the first end 133A and the second end 133B are located closer to the top end 122 of each of the pair of beams 120 than to the fixed end 121.

[0064] In addition, such as Figure 3 As shown, in this embodiment, when viewed from the stacking direction of the multiple layers 10, the lengths of the paths extending from the first connecting portion 132A and the second connecting portion 132B toward the connection portion with the bridging portion 131, i.e., the extension lengths L of each of the first connecting portion 132A and the second connecting portion 132B, are the same. Furthermore, when viewed from the stacking direction, the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B in a direction orthogonal to the direction along the paths extending from the first connecting portion 132A and the second connecting portion 132B toward the connection portion with the bridging portion 131, is the same. When viewed from the stacking direction, the extension length L of each of the first connecting portion 132A and the second connecting portion 132B is larger than the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B. When viewed from the aforementioned stacking direction, the extension length L of each of the first connecting portion 132A and the second connecting portion 132B is larger than the shortest length b from the connecting portion 130 to the top portion 122. When viewed from the stacking direction of the multiple layers 10, the extension length L of each of the first connecting portion 132A and the second connecting portion 132B is larger than the maximum width a of the bridging portion 131 in a direction orthogonal to the direction opposite to the pair of beam portions 120. When viewed from the stacking direction of the multiple layers 10, the maximum width a of the bridging portion 131 is larger than the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0065] Furthermore, the smaller the extension length L of each of the first connecting portion 132A and the second connecting portion 132B, the more firmly the pair of beam portions 120 are connected, and the smaller the vibration deviation of the pair of beam portions 120. Conversely, the larger the extension length L of each of the first connecting portion 132A and the second connecting portion 132B, the better it suppresses the increase in the resonant frequency of the vibration of the pair of beam portions. The larger the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B, the more firmly the pair of beam portions 120 are connected. The smaller the minimum length b from the connecting portion 130 to the top portion 122, the more firmly the pair of beam portions 120 are connected. The maximum width a of the bridging portion 131 affects the resonant frequency of the connecting portion 130 when the connecting portion 130 vibrates.

[0066] In this embodiment, the extension length L of each of the first connecting portion 132A and the second connecting portion 132B is, for example, 10 μm or more and 200 μm or less. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is, for example, 10 μm. The shortest length b from the connecting portion 130 to the top end portion 122 is, for example, 25 μm. The maximum width a of the bridging portion 131 is, for example, 15 μm.

[0067] Moreover, such as Figure 1 and Figure 3 As shown, a first slit 141, a second slit 142, and an outer peripheral slit 143 are provided between a pair of beam portions 120.

[0068] In this embodiment, the first slit 141 is partially formed by a pair of adjacent end edges of a pair of beam portions 120. The second slit 142 is formed at a different location by another portion of a pair of adjacent end edges of a pair of beam portions 120. Specifically, the first slit 141 and the second slit 142, when viewed from the aforementioned stacking direction, are located along an imaginary straight line extending from one of the two endpoints of the fixed end 121 of each pair of beam portions 120 toward the top end portion 122. The connecting portion 130 is located at least between the first slit 141 and the second slit 142.

[0069] In this embodiment, the first slit 141 is located on the fixed end 121 side of each of the pair of beams 120 relative to the bridging portion 131. The second slit 142 is located on the top end 122 side of each of the pair of beams 120 relative to the bridging portion 131. The first connecting portion 132A and the second connecting portion 132B both extend along the directions in which the first slit 141 and the second slit 142 extend, respectively. In this embodiment, the second slit 142 is located on the inner circumferential side of the folded-back portion of the connecting portion 130 at the bridging portion 131. Furthermore, the second slit 142 is located between the first connecting portion 132A and the second connecting portion 132B. The portion of the second slit 142 located between the first connecting portion 132A and the second connecting portion 132B is formed by the end edge of the first connecting portion 132A and the end edge of the second connecting portion 132B. That is, in this embodiment, in the direction in which a pair of beams 120 are arranged, the first end portion 133A and the second end portion 133B are opposite to each other across the second slit 142.

[0070] In this embodiment, the outer peripheral slit 143 is formed at least by the outer peripheral edge of the folded-back portion of the connecting portion 130 at the bridging portion 131 and the respective end edges of the pair of beam portions 120. The first slit 141 is connected to the outer peripheral slit 143. More specifically, the outer peripheral slit 143 extends continuously between the first connecting portion 132A and one of the pair of beam portions 120. The outer peripheral slit 143 extends continuously between the second connecting portion 132B and the other of the pair of beam portions 120.

[0071] More specifically, the peripheral slit 143 is formed such that it extends from the connection portion with the first slit 141 in an orthogonal direction orthogonal to the extension direction of the first slit 141, and wraps around both ends of the bridging portion 131 in its extension direction. Furthermore, the peripheral slit 143 extends parallel to the second slit 142 from one end of the bridging portion 131 in its extension direction toward a position adjacent to the first end portion 133A. The peripheral slit 143 extends parallel to the second slit 142 from the other end of the bridging portion 131 in its extension direction toward a position adjacent to the second end portion 133B. That is, the peripheral slit 143 has a generally U-shaped shape, such as the portion surrounding the second slit 142 located on the side of the first slit 141.

[0072] When viewed from the aforementioned stacking direction, the widths of the first slit 141, the second slit 142, and the peripheral slit 143 are preferably 10 μm or less, and more preferably 1 μm or less.

[0073] In this embodiment, when viewed from the stacking direction, the bridging portion 131, the first connecting portion 132A, and the second connecting portion 132B each have a rectangular shape, but the shape of each of the bridging portion 131, the first connecting portion 132A, and the second connecting portion 132B is not particularly limited. When viewed from the stacking direction, the shapes of the first connecting portion 132A and the second connecting portion 132B may be approximately elliptical or polygonal. Alternatively, the side surfaces of the bridging portion 131, the first connecting portion 132A, and the second connecting portion 132B extending in the stacking direction may be curved when viewed from the stacking direction.

[0074] Figure 4 This is a partial top view of the piezoelectric device according to the first modification of Embodiment 1 of the present invention. Figure 4 In the middle, it is shown that... Figure 1 The same parts as the piezoelectric device 100 of Embodiment 1 of the present invention are shown. For example... Figure 4 As shown, in the piezoelectric device 100a of the first variation of Embodiment 1 of the present invention, the side of the bridging portion 131 extending in the stacking direction on the outer periphery of the folded-back portion of the connecting portion 130 is bent when viewed from the stacking direction. Furthermore, in the first connecting portion 132A, the vicinity of the first end 133A of the side of the beam portion 120 directly connected to the first connecting portion 132A in the pair of beam portions 120 is bent when viewed from the stacking direction. In the second connecting portion 132B, the vicinity of the second end 133B of the side of the beam portion 120 directly connected to the second connecting portion 132B in the pair of beam portions 120 is bent when viewed from the stacking direction. Specifically, the side of the first connecting portion 132A is bent when viewed from the stacking direction in such a way that its width in an orthogonal direction orthogonal to the extending direction of the first connecting portion 132A increases as it approaches the first end 133A. The aforementioned side surface of the second connecting portion 132B bends when viewed from the aforementioned stacking direction, such that its width in an orthogonal direction orthogonal to the extending direction of the second connecting portion 132B increases as it approaches the second end portion 133B. In this way, the bending of the aforementioned side surface of the bridging portion 131 reduces the internal stress of the connecting portion 130.

[0075] like Figure 1 As shown, the piezoelectric device 100 of Embodiment 1 of the present invention includes four beam portions 120 as a plurality of beam portions 120 and four connecting portions 130 as connecting portions 130. The four beam portions 120 are respectively located along the same plane. The four beam portions 120 extend toward an imaginary center point and are adjacent to each other in the circumferential direction of the imaginary center point. The four connecting portions 130 are respectively located between adjacent beam portions 120 and connect adjacent pairs of beam portions 120 to each other.

[0076] In this embodiment, the four beam portions 120 are configured in a manner that is rotationally symmetrical about the imaginary center point when viewed from the stacking direction. The four connecting portions 130 are also configured in a manner that is rotationally symmetrical about the imaginary center point when viewed from the stacking direction.

[0077] Next, we will explain multiple layers 10. For example... Figure 2 As shown, in this embodiment, the plurality of layers 10 have a piezoelectric layer 11, a first electrode layer 12, and a second electrode layer 13.

[0078] The piezoelectric layer 11 is composed of a single-crystal piezoelectric material. The cutting orientation of the piezoelectric layer 11 is appropriately selected to achieve the desired device characteristics. In this embodiment, the piezoelectric layer 11 is formed by thinning a single-crystal substrate, specifically a rotary Y-cut substrate. Furthermore, the cutting orientation of this rotary Y-cut substrate is specifically 30°. Additionally, the thickness of the piezoelectric layer 11 is, for example, 0.3 μm or more and 5.0 μm or less. The aforementioned single-crystal piezoelectric material has a polarization axis. Details regarding the axial direction of the polarization axis will be described later.

[0079] The material constituting the piezoelectric layer 11 is appropriately selected to enable the piezoelectric device 100 to exhibit the desired device characteristics. In this embodiment, the piezoelectric layer 11 is composed of an inorganic material. Specifically, the piezoelectric layer 11 is composed of a basic niobate-based compound or a basic tantalate-based compound. In this embodiment, the alkali metal contained in the aforementioned basic niobate-based compound or the aforementioned basic tantalate-based compound is at least one of lithium, sodium, and potassium. In this embodiment, the piezoelectric layer 11 is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

[0080] like Figure 2 As shown, the first electrode layer 12 is disposed on one side of the piezoelectric layer 11 in the stacking direction of the plurality of layers 10. The second electrode layer 13 is disposed on the other side of the piezoelectric layer 11, at least partially opposite to the first electrode layer 12, separated from the piezoelectric layer 11. Furthermore, in this embodiment, a sealing layer (not shown) is disposed between the first electrode layer 12 and the piezoelectric layer 11, between the second electrode layer 13 and the piezoelectric layer 11, and between the second electrode layer 13 and the piezoelectric layer 11. Additionally, in each of the plurality of beam portions 120, the first electrode layer 12 and the second electrode layer 13 are respectively disposed such that they do not face each of the slits in the first slit 141, the second slit 142, and the peripheral slit 143.

[0081] In this embodiment, the first electrode layer 12 and the second electrode layer 13 are each made of Pt. The first electrode layer 12 and the second electrode layer 13 may also be made of other materials such as Al. The sealing layer is made of Ti. The sealing layer may also be made of other materials such as NiCr. The first electrode layer 12, the second electrode layer 13, and the sealing layer may each be an epitaxially grown film. When the piezoelectric layer 11 is made of lithium niobate (LiNbO3), from the viewpoint of suppressing the diffusion of the material constituting the sealing layer into the first electrode layer 12 or the second electrode layer 13, it is preferable that the sealing layer is made of NiCr. This improves the reliability of the piezoelectric device 100.

[0082] In this embodiment, the thickness of each of the first electrode layer 12 and the second electrode layer 13 is, for example, 0.05 μm or more and 0.2 μm or less. The thickness of the sealing layer is, for example, 0.005 μm or more and 0.05 μm or less.

[0083] The plurality of layers 10 further include a support layer 14. The support layer 14 is disposed on the side of the piezoelectric layer 11 opposite to the side of the first electrode layer 12 and on the side of the second electrode layer 13 opposite to the side of the piezoelectric layer 11. The support layer 14 has a first support portion 14a and a second support portion 14b stacked on the side of the first support portion 14a opposite to the side of the piezoelectric layer 11. In this embodiment, the first support portion 14a is made of SiO2 and the second support portion 14b is made of single crystal Si. In this embodiment, from the viewpoint of bending vibration of the plurality of beam portions 120, it is preferable that the thickness of the support layer 14 is thicker than the thickness of the piezoelectric layer 11. Furthermore, the mechanism of bending vibration of the plurality of beam portions 120 will be described later.

[0084] In addition, such as Figure 2 As shown, in this embodiment, the connecting portion 130 is formed by multiple layers 10 constituting each of the multiple beam portions 120 continuously in an orthogonal direction orthogonal to the stacking direction. However, in this embodiment, the multiple layers 10 of the connecting portion 130 do not include the first electrode layer 12 and the second electrode layer 13.

[0085] Furthermore, the components constituting the base 110 are described. For example... Figure 2 As shown, in this embodiment, the base 110 includes a plurality of layers 10, similar to the plurality of beam portions 120. The plurality of layers 10 of the base 110 are formed continuously through the plurality of layers 10 of the plurality of beam portions 120. Specifically, the piezoelectric layer 11, the first electrode layer 12, the second electrode layer 13, and the support layer 14 constituting the base 110 are formed continuously with the piezoelectric layer 11, the first electrode layer 12, the second electrode layer 13, and the support layer 14 constituting the plurality of beam portions 120, respectively. Furthermore, the base 110 also includes a substrate layer 15, a first connecting electrode layer 20, and a second connecting electrode layer 30.

[0086] The substrate layer 15 is axially connected to the support layer 14 on the side opposite to the piezoelectric layer 11 along the central axis. The substrate layer 15 includes a first substrate layer 15a and a second substrate layer 15b stacked on the side of the first substrate layer 15a opposite to the support layer 14 along the central axis. In this embodiment, the first substrate layer 15a is made of SiO2, and the second substrate layer 15b is made of single-crystal Si.

[0087] like Figure 2 As shown, the first connecting electrode layer 20 is electrically connected to the first electrode layer 12 via a sealing layer (not shown) and is exposed to the outside. Specifically, the first connecting electrode layer 20 is disposed on the side of the second electrode layer 13 of the base 110 opposite to the side of the support layer 14.

[0088] The thickness of each of the first connecting electrode layer 20 and the second connecting electrode layer 30 is, for example, 0.1 μm or more and 1.0 μm or less. The thickness of the sealing layer connected to the first connecting electrode layer 20 and the sealing layer connected to the second connecting electrode layer 30 is, for example, 0.005 μm or more and 0.1 μm or less.

[0089] In this embodiment, the first connecting electrode layer 20 and the second connecting electrode layer 30 are both made of Au. The first connecting electrode layer 20 and the second connecting electrode layer 30 may also be made of other conductive materials such as Al. The sealing layer connected to the first connecting electrode layer 20 and the sealing layer connected to the second connecting electrode layer 30 are, for example, made of Ti. These sealing layers may also be made of NiCr.

[0090] like Figure 2 As shown, the piezoelectric device 100 of this embodiment has an opening 101 that opens toward the side opposite to the piezoelectric layer 11 in the aforementioned stacking direction. In this embodiment, the opening 101 is a space surrounded by a base 110, a plurality of beams 120, a plurality of connecting portions 130, a first slit 141, a second slit 142, and an outer peripheral slit 143.

[0091] Here, the axial direction of the polarization axis of the single-crystal piezoelectric material constituting the piezoelectric layer 11 will be explained. Preferably, when the polarization axis of the single-crystal piezoelectric material is projected from the stacking direction onto an imaginary plane orthogonal to the stacking direction, the axial direction of the imaginary axis extends in the same direction in any of the plurality of beam portions 120, and when viewed from the stacking direction, the angle formed with the respective extension directions of the first slit 141 and the second slit 142 is not 45 degrees or 135 degrees. More specifically, in this embodiment, it is more preferable that the angle formed by the axial direction of the imaginary axis with the respective extension directions of the first slit 141 and the second slit 142 when viewed from the stacking direction is 0 degrees or more and 5 degrees or less, 85 degrees or more and 95 degrees or less, or 175 degrees or more and less than 180 degrees. Furthermore, more preferably, when viewed from the aforementioned stacking direction, the angle formed by the extension direction of each of the plurality of beam portions 120 and the axial direction of the aforementioned imaginary axis when viewed from the stacking direction is either 40 degrees or more and 50 degrees or less, or 130 degrees or more and 140 degrees or less. Preferably, the axial direction of the aforementioned imaginary axis of the piezoelectric device 100 of this embodiment holds the aforementioned relationship with respect to any one of the first slit 141, the second slit 142, and the bridging portion 131. The reasons for the preferred range of each angle related to the aforementioned imaginary axis will be explained later.

[0092] In this embodiment, the axial direction of the aforementioned imaginary axis is oriented in a specific direction, but the axial direction of the aforementioned imaginary axis is not particularly limited.

[0093] Furthermore, in this embodiment, the single-crystal piezoelectric material has a polarization axis. Therefore, due to the thermal stress generated in the multiple beam portions 120, the multiple beam portions 120 sometimes warp when viewed from an orthogonal direction orthogonal to the aforementioned stacking direction. Examples of deformations in which the multiple beam portions 120 warp are described below.

[0094] Figure 5 This is a top view of the piezoelectric device of the second variation of Embodiment 1 of the present invention. Figure 6 Observe from the direction of the arrow on line VI-VI Figure 5 A partial cross-sectional view obtained from the piezoelectric device shown.

[0095] like Figure 5 As shown, in the piezoelectric device 100b of the second variation of Embodiment 1 of the present invention, when viewed from the stacking direction, the axial direction of the above-mentioned imaginary axis forms an angle of 45 degrees with the plurality of first slits 141 and the plurality of second slits 142 respectively.

[0096] Therefore, in this modified example, the length L1 of the imaginary shaft, viewed from the stacking direction, from the center of the connecting portion 130 to the opposite end of one of the beam portions 120, and the length L2 of the imaginary shaft, viewed from the center of the connecting portion 130 to the opposite end of the other beam portion 120, are different from each other. Furthermore, the end of one of the beam portions 120, viewed from the stacking direction, on the side opposite to the center of the connecting portion 130, is not a fixed end 121. On the other hand, the end of the other beam portion 120, viewed from the stacking direction, on the side opposite to the center of the connecting portion 130, is a fixed end 121. Therefore, when thermal stress is applied to the multiple beam portions 120, the pair of beam portions 120 warp in different ways near the connecting portion 130.

[0097] In this modified example of the piezoelectric device 100b, the aforementioned thermal stress is applied to the plurality of beams 120. As a result, as Figure 6 As shown, when the piezoelectric device 100b is not driven, the ends of the pair of beams 120 near the center of the connecting portion 130 are located at different positions relative to each other in the aforementioned stacking direction.

[0098] Figure 7 This is a top view of the piezoelectric device of the third variation of Embodiment 1 of the present invention. Figure 8 Observe from the direction of the arrow on line VIII-VIII Figure 7 A partial cross-sectional view obtained from the piezoelectric device shown. Figure 9 Observe from the direction of the arrow on line IX-IX Figure 7 A partial cross-sectional view obtained from the piezoelectric device shown.

[0099] like Figure 7 As shown, in the piezoelectric device 100c of the third variation of Embodiment 1 of the present invention, when viewed from the above-mentioned stacking direction, the axial direction of the imaginary axis of the single crystal piezoelectric body forms an angle of 0 degrees or 90 degrees with the plurality of first slits 141 and the plurality of second slits 142, respectively.

[0100] Therefore, in this modified example, the length L1 of the imaginary axis, viewed from the stacking direction, from the center of the connecting portion 130 to the opposite end of one of the beam portions 120, and the length L2 of the imaginary axis, viewed from the center of the connecting portion 130, to the opposite end of the other beam portion 120, are the same. Furthermore, in the axial direction of the imaginary axis, viewed from the stacking direction, the distance from the end of one beam portion 120 near the center of the connecting portion 130 to the fixed end 121, and the distance from the end of the other beam portion 120 near the center of the connecting portion 130 to the fixed end 121, are the same.

[0101] Furthermore, in the piezoelectric device 100c of this modified example, the multiple beams 120 warp individually by applying thermal stress to them. As a result, such as Figure 8 As shown, when the piezoelectric device 100c is not driven, the ends of the central side of the connection portion 130 of the pair of beam portions 120 near the center of the connection portion 130 are located at approximately the same position in the aforementioned stacking direction. Thus, in this modified example, even if the multiple beam portions 120 warp due to thermal stress, damage to the connection portion 130 can be suppressed, especially damage to the bridging portion 131.

[0102] As described above, by comparing the piezoelectric device 100b of the second variation of Embodiment 1 of the present invention with the piezoelectric device 100c of the third variation, it can be seen that in Embodiment 1 of the present invention, when viewed from the stacking direction, if the angle between the axial direction of the above-mentioned imaginary axis and the respective extension directions of the first slit 141 and the second slit 142 is 45 degrees or 135 degrees, the closer it is to 0 degrees or 90 degrees, the more effectively the difference in displacement caused by the thermal stress of the pair of beams 120 can be suppressed. Similarly, it can be seen that in Embodiment 2 of the present invention, when viewed from the stacking direction, if the angle between the axial direction of the above-mentioned imaginary axis and the respective extension directions of the plurality of beams 120 is 0 degrees or 90 degrees, the closer it is to 45 degrees or 135 degrees, the more effectively the difference in displacement caused by the thermal stress of the pair of beams 120 can be suppressed.

[0103] In addition, such as Figure 9 As shown, in the piezoelectric device 100c of the third variation of Embodiment 1 of the present invention, when each beam of a pair of beams 120 is viewed from the first slit 141 side and the second slit 142 side, the pair of beams 120 are tilted in either direction of the stacking direction.

[0104] The piezoelectric device 100 of Embodiment 1 of the present invention is configured such that a plurality of beams 120 are each capable of bending and vibrating. Here, the mechanism of bending and vibrating of the plurality of beams 120 will be explained.

[0105] Figure 10This is a partial cross-sectional view schematically showing the beam portion of the piezoelectric device according to Embodiment 1 of the present invention. Figure 11 This is a partial cross-sectional view schematically showing the beam portion of the piezoelectric device according to Embodiment 1 of the present invention during operation. Furthermore, in Figure 10 and Figure 11 The first and second electrode layers are not shown in the figure.

[0106] like Figure 10 and Figure 11 As shown, in this embodiment, among the plurality of beam portions 120, the piezoelectric layer 11 functions as a stretchable layer capable of stretching and contracting in an in-plane direction orthogonal to the aforementioned stacking direction, while the layers other than the piezoelectric layer 11 function as constraint layers. In this embodiment, the main support layer 14 functions as a constraint layer. Thus, the constraint layer is stacked on top of the stretchable layer in a direction orthogonal to the stretching direction of the stretchable layer. Furthermore, the plurality of beam portions 120 may also include a reverse stretchable layer instead of a constraint layer, which is capable of contracting in the in-plane direction when the stretchable layer extends in the in-plane direction, and extending in the in-plane direction when the stretchable layer contracts in the in-plane direction.

[0107] Furthermore, when the piezoelectric layer 11, which serves as a stretching layer, is to stretch or contract in the aforementioned in-plane direction, the support layer 14, which is the main part of the constraint layer, constrains the stretching or contraction of the piezoelectric layer 11 at the interface with the piezoelectric layer 11. Additionally, in this embodiment, in each of the plurality of beam portions 120, the piezoelectric layer 11, which serves as a stretching layer, is located only on one side of the stress neutral plane N of each of the plurality of beam portions 120. The center of gravity of the support layer 14, which mainly constitutes the constraint layer, is located on the other side of the stress neutral plane N. Thus, as... Figure 10 and Figure 11 As shown, when the piezoelectric layer 11, which serves as a stretching layer, stretches and contracts in the aforementioned in-plane direction, the plurality of beam portions 120 bend in an orthogonal direction to the aforementioned in-plane direction. Furthermore, the longer the separation distance between the stress-neutral surface N and the piezoelectric layer 11, the greater the displacement of each of the plurality of beam portions 120 when they bend. Additionally, the greater the stress on the piezoelectric layer 11 that is about to stretch and contract, the greater the displacement. Thus, the plurality of beam portions 120 bend and vibrate in an orthogonal direction to the aforementioned in-plane direction, starting from a fixed end 121.

[0108] Furthermore, in the piezoelectric device 100 of this embodiment, the connection portion 130 facilitates the generation of vibrations in the basic vibration mode and suppresses the generation of vibrations in the composite vibration mode. The basic vibration mode refers to a mode in which the phases of the multiple beams 120 bending and vibrating are consistent, and the multiple beams 120 as a whole are displaced in either the up or down direction. On the other hand, the composite vibration mode refers to a mode in which the phase of at least one of the multiple beams 120 is inconsistent with the phases of the other beams 120 when the multiple beams 120 bending and vibrating.

[0109] Figure 12 This is a perspective view illustrating the vibration state of the piezoelectric device according to Embodiment 1 of the present invention in a basic vibration mode, using simulation. Specifically, in Figure 12 The image shows a piezoelectric device 100 in which multiple beams 120 are displaced toward the first electrode layer 12. Additionally, in... Figure 12 In the process, the greater the displacement of the multiple beams 120 towards the first electrode layer 12, the lighter the color. Furthermore, in... Figure 12 The layers that make up the multiple layers 10 are not shown in the figure.

[0110] like Figure 12 As shown, for each of the multiple beam sections 120, adjacent pairs of beam sections 120 are connected to each other by a connecting part 130, thereby suppressing the generation of composite vibration modes.

[0111] Furthermore, in the connecting portion 130 of the piezoelectric device 100 of this embodiment, the first end portion 133A and the second end portion 133B are respectively located closer to the top end portion 122 of the pair of beam portions 120 than to the fixed end portion 121. As a result, the plurality of beam portions 120 are more firmly connected to each other, and the phase of the vibration of each of the plurality of beam portions 120 is more easily synchronized. In addition, the connecting portion 130 of the piezoelectric device 100 of this embodiment includes a bridging portion 131, which folds back and connects the pair of beam portions 120 to each other. Therefore, when the multiple beams 120 vibrate, the first connecting part 132A and the second connecting part 132B of the connecting part 130 function like leaf springs. The connecting part 130 connects a pair of beams 120 to each other, and the first connecting part 132A and the second connecting part 132B are connected in series via the bridging part 131. The length of the connecting part 130 as a leaf spring becomes longer, thereby preventing its connection force from becoming too strong.

[0112] The piezoelectric device 100 of this embodiment readily generates vibrations in the basic vibration mode and suppresses the generation of composite vibration modes, thus improving device characteristics, especially when used as an ultrasonic transducer. Hereinafter, the functional operation of the piezoelectric device 100 when used as an ultrasonic transducer will be explained.

[0113] First, such as Figure 2As shown, when ultrasonic waves are generated by the piezoelectric device 100, a voltage is applied between the first connecting electrode layer 20 and the second connecting electrode layer 30. Furthermore, a voltage is applied between the first electrode layer 12 connected to the first connecting electrode layer 20 and the second electrode layer 13 connected to the second connecting electrode layer 30. Moreover, in each of the plurality of beam portions 120, a voltage is applied between the opposing first electrode layer 12 and second electrode layer 13 via the piezoelectric body layer 11. Thus, the piezoelectric body layer 11 expands and contracts in an in-plane direction orthogonal to the aforementioned stacking direction, and therefore, according to the above mechanism, the plurality of beam portions 120 bend and vibrate along the aforementioned stacking direction. Therefore, by applying force to the medium surrounding the plurality of beam portions 120 of the piezoelectric device 100, the medium vibrates, thereby generating ultrasonic waves.

[0114] Furthermore, in the piezoelectric device 100 of this embodiment, each of the plurality of beams 120 has an inherent mechanical resonant frequency. Therefore, when the applied voltage is a sinusoidal voltage and the frequency of the sinusoidal voltage is close to the aforementioned resonant frequency, the displacement of each of the plurality of beams 120 when bending increases.

[0115] When detecting ultrasonic waves using the piezoelectric device 100, the medium surrounding each of the plurality of beams 120 vibrates due to the ultrasonic waves, applying force to each beam 120 from the surrounding medium, causing each beam 120 to bend and vibrate. When the plurality of beams 120 bend and vibrate, stress is applied to the piezoelectric layer 11. This stress induces charges in the piezoelectric layer 11. Using the charges induced in the piezoelectric layer 11, a potential difference is generated between the first electrode layer 12 and the second electrode layer 13, which are separated by the piezoelectric layer 11. This potential difference is detected in the first connecting electrode layer 20 connected to the first electrode layer 12 and the second connecting electrode layer 30 connected to the second electrode layer 13. Therefore, ultrasonic waves can be detected in the piezoelectric device 100.

[0116] Furthermore, when the ultrasonic wave being tested contains a large number of specific frequency components and these frequency components are close to the aforementioned resonant frequency, the displacement of the multiple beams 120 during bending vibration increases. This increase in displacement leads to a larger potential difference.

[0117] Thus, when the piezoelectric device 100 of this embodiment is used as an ultrasonic transducer, the design of the resonant frequencies of the plurality of beams 120 becomes important. These resonant frequencies vary depending on the length of each beam 120 in its extending direction, the axial thickness of the central axis, the length of the fixed end 121 when viewed from that axial direction, and the density and elastic modulus of the materials constituting the plurality of beams 120. Furthermore, it is preferable that the plurality of beams each have the same resonant frequency. For example, when the thicknesses of the plurality of beams 120 are different, by adjusting the length of each beam 120 in its extending direction, the plurality of beams 120 can each have the same resonant frequency.

[0118] For example, in Figures 1-3 In the piezoelectric device 100 of Embodiment 1 of the present invention shown, when the resonant frequency of each of the plurality of beam portions 120 is designed to be around 40kHz, for each of the plurality of beam portions 120, the structural material of the piezoelectric layer 11 is lithium niobate, the thickness of the piezoelectric layer 11 is 1μm, the thickness of the first electrode layer 12 and the second electrode layer 13 is 0.1μm, the thickness of the first support portion 14a is 0.8μm, the thickness of the second support portion 14b is 1.4μm, the shortest distance from the fixed end 121 to the top end 122 of each of the plurality of beam portions 120 is 400μm, and the length of the fixed end 121 when viewed from the above-mentioned stacking direction is 800μm.

[0119] Furthermore, the piezoelectric device 100 of this embodiment, by providing the connecting portion 130 with the above-described structure, easily generates vibration in the basic vibration mode and suppresses the generation of composite vibration modes. Therefore, when the piezoelectric device 100 is used as an ultrasonic transducer, even when detecting ultrasonic waves with the same frequency component as the resonant frequency, the phase difference of the vibrations of the multiple beam portions 120 can be suppressed. Furthermore, it is possible to suppress the situation where the charges generated in the piezoelectric layer 11 of each of the multiple beam portions 120 cancel each other out in the first electrode layer 12 or the second electrode layer 13 due to the phase difference of the vibrations of the multiple beam portions 120.

[0120] In this way, the device characteristics of the piezoelectric device 100 as an ultrasonic transducer are improved.

[0121] The following describes a method for manufacturing the piezoelectric device 100 according to Embodiment 1 of the present invention. Figure 13 This is a cross-sectional view showing the state in which a second electrode layer is provided on a piezoelectric single-crystal substrate in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 13 and the following Figures 14-19 In, with Figure 2 The same sectional view is illustrated.

[0122] like Figure 13 As shown, firstly, an adhesive layer (not shown) is formed on the lower surface of the piezoelectric single-crystal substrate 11a, and then a second electrode layer 13 is formed on the side of the adhesive layer opposite to the piezoelectric single-crystal substrate 11a. The second electrode layer 13 is formed into a desired pattern by a vapor deposition and lift-off method. Alternatively, the second electrode layer 13 can be formed by sputtering the entire lower surface of the piezoelectric single-crystal substrate 11a and then etching to form the desired pattern. The second electrode layer 13 and the adhesive layer can also be epitaxially grown.

[0123] Figure 14 This is a cross-sectional view showing the state in which the first support portion is provided during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 14 As shown, a first support portion 14a is formed on the lower surface of both the piezoelectric single crystal substrate 11a and the second electrode layer 13 using methods such as CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). Immediately after the first support portion 14a is formed, a portion of the lower surface of the first support portion 14a located on the side opposite to the second electrode layer 13 protrudes. Therefore, the lower surface of the first support portion 14a is planarized by cutting it using methods such as Chemical Mechanical Polishing (CMP).

[0124] Figure 15 This is a cross-sectional view showing the state in which the laminate is joined to the first support portion during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 15 As shown, the laminate 16, consisting of the second support portion 14b and the substrate layer 15, is bonded to the lower surface of the first support portion 14a by surface activation bonding or atomic diffusion bonding. In this embodiment, the laminate 16 is an SOI (Silicon on Insulator) substrate. Furthermore, by pre-planarizing the upper surface of the second support portion 14b using CMP or the like, the yield of the piezoelectric device 100 is improved.

[0125] Figure 16 This is a cross-sectional view showing the state in which a piezoelectric layer is formed by cutting a piezoelectric single-crystal substrate in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 15 and Figure 16 As shown, the upper surface of the piezoelectric single crystal substrate 11a is thinned by grinding with a grinding machine. The thinned upper surface of the piezoelectric single crystal substrate 11a is further polished by CMP or the like, so that the piezoelectric single crystal substrate 11a is formed into a piezoelectric layer 11.

[0126] Alternatively, a release layer can be formed by pre-implanting ions onto the upper surface of the piezoelectric single crystal substrate 11a, and the piezoelectric single crystal substrate 11a can be formed into a piezoelectric layer 11 by peeling off the release layer. Alternatively, the piezoelectric single crystal substrate 11a can be further polished using CMP or the like to form a piezoelectric layer 11.

[0127] Figure 17 This is a cross-sectional view showing the state in which a first electrode layer is provided in the piezoelectric body layer during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 17 As shown, an adhesive layer (not shown) is formed on the upper surface of the piezoelectric layer 11, and then a first electrode layer 12 is formed on the side of the adhesive layer opposite to the piezoelectric layer 11. The first electrode layer 12 is formed with a desired pattern by vapor deposition and lift-off. Alternatively, the first electrode layer 12 can be formed by sputtering over the entire upper surface of the piezoelectric layer 11 and then etching to form the desired pattern. The first electrode layer 12 and the adhesive layer can also be epitaxially grown.

[0128] Figure 18 This is a cross-sectional view showing the state in which the groove and recess are provided during the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 18 As shown, when viewed from the aforementioned stacking direction, in a region corresponding to the area inside the base 110 of the piezoelectric device 100, a slit is formed in the piezoelectric layer 11 and the first support portion 14a by dry etching using RIE (Reactive Ion Etching) or the like. This slit can also be formed by wet etching using fluorinated nitric acid or the like. Furthermore, the second support portion 14b exposed to the slit is etched using DRIE (Deep Reactive Ion Etching) so that the slit reaches the upper surface of the substrate layer 15. Thus, a slit corresponding to the base 110 of the piezoelectric device 100 is formed. Figure 1 and Figure 2 The first slit 141, the second slit 142, and the outer peripheral slit 143 of the piezoelectric device 100 shown Figure 18 The groove 17 shown.

[0129] Moreover, such as Figure 18 As shown, in the portion corresponding to the base 110 of the piezoelectric device 100, the piezoelectric layer 11 is etched by the aforementioned dry etching or wet etching to partially expose the second electrode layer 13. This forms a recess 18.

[0130] Figure 19 This is a partial cross-sectional view showing the state in which the first connecting electrode layer and the second electrode connecting layer are provided in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Furthermore, as... Figure 19As shown, in the portion corresponding to the base 110, adhesive layers (not shown) are respectively provided on the first electrode layer 12 and the second electrode layer 13. Then, the first connecting electrode layer 20 and the second connecting electrode layer 30 are formed on the upper surface of each adhesive layer by a vapor deposition stripping method. Alternatively, the first connecting electrode layer 20 and the second connecting electrode layer 30 can be formed by sputtering the entire surface of the piezoelectric layer 11, the first electrode layer 12, and the exposed second electrode layer 13, and then forming a desired pattern by etching.

[0131] And, as Figure 19 and Figure 2 As shown, finally, a portion of the second substrate layer 15b in the substrate layer 15 is removed using DRIE, and then a portion of the first substrate layer 15a is removed using RIE. This creates an opening 101 and forms a plurality of beam portions 120 and connecting portions 130.

[0132] Through the above-described processes, manufacturing Figures 1-3 The piezoelectric device 100 of Embodiment 1 of the present invention is shown as shown.

[0133] As described above, the piezoelectric device 100 of Embodiment 1 of the present invention includes a base 110, a plurality of beam portions 120, and a connecting portion 130. Each of the plurality of beam portions 120 has a fixed end portion 121 and a top end portion 122. The fixed end portion 121 is connected to the base 110. The top end portion 122 is located on the side opposite to the fixed end portion 121. Each of the plurality of beam portions 120 extends from the fixed end portion 121 toward the top end portion 122. Each of the plurality of beam portions 120 is a piezoelectric vibrating portion comprising a plurality of layers 10. The connecting portion 130 connects a pair of adjacent beam portions 120 to each other. A first slit 141 and a second slit 142 are provided between each pair of beam portions 120. The first slit 141 is formed by a portion of the adjacent end edges of each pair of beam portions 120. The second slit 142 is formed at a different location from the first slit 141 by another portion of the adjacent end edges of each pair of beam portions 120. The connecting portion 130 is located at least between the first slit 141 and the second slit 142. The connecting portion 130 has a first end portion 133A, a second end portion 133B, a bridging portion 131, a first connecting portion 132A, and a second connecting portion 132B. The connecting portion 130 is connected at the first end portion 133A to one of the pair of beam portions 120. The connecting portion 130 is connected at the second end portion 133B to the other of the pair of beam portions 120. The second end portion 133B is opposite to the first end portion 133A in the direction in which the pair of beam portions 120 are arranged. The bridging portion 131 is folded back between the pair of beam portions 120 and is provided for connecting the pair of beam portions 120 to each other. The first connecting portion 132A is connected to the portion of the bridging portion 131 located on one side of the pair of beam portions 120. The second connecting portion 132B is connected to the portion of the bridging portion 131 located on the other side of the pair of beam portions 120. The second connecting portion 132B is located along the first connecting portion 132A. The connecting portion 130 has only one first end portion 133A. The connecting portion 130 has only one second end portion 133B. The first end portion 133A and the second end portion 133B are respectively located closer to the top end portion 122 of the pair of beam portions 120 than to the fixed end portion 121.

[0134] Therefore, it is possible to increase the resonant frequency while suppressing the vibration of each of the multiple beams 120, and reduce the vibration deviation.

[0135] In this embodiment, an outer peripheral slit 143 is formed between the pair of beam portions 120 by the outer peripheral edge of the folded-back portion of the connecting portion 130 at the bridging portion 131 and the respective end edge of the pair of beam portions 120. A first slit 141 connects to the outer peripheral slit 143. A second slit 142 is located on the inner peripheral side of the folded-back portion of the connecting portion 130 at the bridging portion 131.

[0136] As a result, the formation of the bridging portion 131 becomes easier, and the movement of the connecting portion 130, especially the bridging portion 131, is suppressed by a pair of beams 120 when multiple beams 120 vibrate.

[0137] In this embodiment, the first connecting portion 132A extends along the second slit 142 starting from the first end portion 133A, and the second connecting portion 132B extends along the second slit 142 starting from the second end portion 133B.

[0138] Therefore, by forming the second slit 142, the first connecting portion 132A and the second connecting portion 132B can be easily formed.

[0139] In this embodiment, the first connecting portion 132A is directly connected to the bridging portion 131 on the side opposite to the first end portion 133A. The second connecting portion 132B is directly connected to the bridging portion 131 on the side opposite to the second end portion 133B.

[0140] Therefore, the number of times the connecting part 130 is folded back is reduced to one, and the connecting part 130 can be constructed from the necessary minimum constituent parts.

[0141] In this embodiment, when viewed from the stacking direction of the plurality of layers 10, the dimension of the extension length L of the first connecting portion 132A and the second connecting portion 132B is larger than the dimension of the minimum width W of the first connecting portion 132A and the second connecting portion 132B in a direction orthogonal to the path extending toward the connection portion of the bridging portion 131.

[0142] Therefore, the connecting force generated by the connecting part 130 becomes too strong when the vibration of multiple beams 120 is suppressed.

[0143] In this embodiment, when viewed from the stacking direction of the multiple layers 10, the lengths of the paths extending from the first connecting portion 132A and the second connecting portion 132B toward the connection portion with the bridging portion 131, i.e., the extension lengths L of the first connecting portion 132A and the second connecting portion 132B, are larger than the shortest length b from the connecting portion 130 to the top portion 122.

[0144] Therefore, by relatively reducing the aforementioned shortest length b, the connection force between the pair of beams 120 generated by the connecting portion 130 is enhanced, and by increasing the size of the aforementioned extension length L, it is possible to prevent the connection force generated by the connecting portion 130 from becoming too strong.

[0145] In this embodiment, when viewed from the stacking direction of the multiple layers 10, the lengths of the paths extending from the first connecting portion 132A and the second connecting portion 132B toward the connection portion with the bridging portion 131, i.e., the extension lengths L of the first connecting portion 132A and the second connecting portion 132B respectively, are larger than the maximum width a of the bridging portion 131 in the direction orthogonal to the direction of the pair of beam portions 120 facing each other.

[0146] Therefore, the maximum width 'a' of the bridging portion 131 in the connecting portion 130 is relatively smaller. That is, the weight of the bridging portion 131 in the connecting portion 130 is relatively smaller. Furthermore, it is possible to suppress the degradation of the piezoelectric device 100's device characteristics due to undesirable vibrations of the bridging portion 131.

[0147] In this embodiment, when viewed from the stacking direction of the multiple layers 10, the maximum width a of the bridging portion 131 in the direction orthogonal to the direction opposite to the pair of beam portions 120 is larger than the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B in the direction orthogonal to the path extending toward the connection portion of the bridging portion 131.

[0148] Thus, the first connecting part 132A and the second connecting part 132B are integrated with the bridge-building part 131. When the multiple beam parts 120 vibrate, the connecting part 130 functions like a leaf spring, which can further suppress the connection force generated by the connecting part 130 from becoming too strong.

[0149] In this embodiment, the first slit 141 is located on the fixed end 121 side of each of the pair of beams 120 relative to the bridging portion 131. The second slit 142 is located on the top end 122 side of each of the pair of beams 120 relative to the bridging portion 131.

[0150] Therefore, since the connecting portion 130 does not directly connect the top ends 122 of each of the pair of beam portions 120 to each other, the connection force generated by the connecting portion 130 on each of the pair of beam portions 120 can be further suppressed from becoming too strong. Moreover, since the first slit 141 is connected to the outer peripheral slit 143 and the second slit 142 is located on the inner peripheral side of the folded-back portion of the connecting portion 130 at the bridging portion 131, the first end 133A and the second end 133B are located closer to the top ends 122, thus further reducing the vibration deviation of the pair of beam portions 120.

[0151] The piezoelectric device 100 according to Embodiment 1 of the present invention includes four beam portions 120 as a plurality of beam portions 120 and four connecting portions 130 as connecting portions 130. The four beam portions 120 are respectively located along the same plane. The four beam portions 120 extend toward an imaginary center point and are adjacent to each other in the circumferential direction of the imaginary center point. The four connecting portions 130 are respectively located between adjacent beam portions 120 and connect adjacent pairs of beam portions 120 to each other.

[0152] Therefore, in the piezoelectric device 100 including four beams 120, the connecting part 130 can be used to reduce the vibration deviation of the four beams 120 while suppressing the resonant frequency of each of the four beams 120 from increasing.

[0153] In this embodiment, the plurality of layers 10 have a piezoelectric layer 11, a first electrode layer 12, and a second electrode layer 13. The piezoelectric layer 11 is made of a single-crystal piezoelectric. The first electrode layer 12 is disposed on one side of the piezoelectric layer 11 in the stacking direction of the plurality of layers 10. The second electrode layer 13 is disposed on the other side of the piezoelectric layer 11 in a manner that is at least partially opposite to the first electrode layer 12, separated from the piezoelectric layer 11. When the polarization axis of the single-crystal piezoelectric is projected from the stacking direction onto an imaginary plane orthogonal to the stacking direction, the axial direction of the imaginary axis extends in the same direction in any of the plurality of beam portions 120, and when viewed from the stacking direction, the angle formed with the respective extension directions of the first slit 141 and the second slit 142 is not 45 degrees.

[0154] Therefore, in a piezoelectric device 100 in which the piezoelectric layer 11 is composed of a single-crystal piezoelectric material with a polarization axis, even if thermal stress is generated in each of the pair of beams 120, the deviation in stress distribution generated in the connection 130 can be reduced and the breakage of the connection 130 can be suppressed.

[0155] In this embodiment, the angle between the axial direction of the above-mentioned imaginary axis and the respective extension directions of the first slit 141 and the second slit 142 when viewed from the stacking direction is 0 degrees or more and 5 degrees or less, 85 degrees or more and 95 degrees or less, or 175 degrees or more and less than 180 degrees.

[0156] Therefore, the deviation in stress distribution generated in the connection 130 can be further reduced, thereby suppressing the breakage of the connection 130.

[0157] In the piezoelectric device 100a of the first variation of Embodiment 1 of the present invention, when each of the beam portions 120 in a pair of beam portions 120 is viewed from the first slit 141 side and the second slit 142 side, the pair of beam portions 120 are tilted in either direction of the stacking direction.

[0158] In the case of such a structure, the piezoelectric device 100a of the first modification of Embodiment 1 of the present invention reduces the deviation of stress distribution generated in the connection portion 130, and thus can suppress the occurrence of damage to the connection portion 130.

[0159] In the piezoelectric device 100 of Embodiment 1 of the present invention, when viewed from the above-mentioned stacking direction, the angle between the extension direction of each of the plurality of beam portions 120 and the axial direction of the above-mentioned imaginary axis is 40 degrees or more and 50 degrees or less, or 130 degrees or more and 140 degrees or less.

[0160] Therefore, even assuming thermal stress is generated in the multiple beams 120, the multiple beams 120 each have approximately the same stress distribution in the extension direction, and thus the warping mode of each of the multiple beams 120 is also approximately the same. Furthermore, it is possible to suppress the degradation of the device characteristics of the piezoelectric device 100.

[0161] In this embodiment, the piezoelectric layer 11 is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

[0162] This improves the piezoelectric properties of the piezoelectric layer 11, thereby improving the device characteristics of the piezoelectric device 100.

[0163] (Implementation Method 2)

[0164] The piezoelectric device according to Embodiment 2 of the present invention will now be described. In the piezoelectric device of Embodiment 2 of the present invention, the number of main beams differs from that of the piezoelectric device 100 of Embodiment 1 of the present invention. Therefore, the same structure as that of the piezoelectric device 100 of Embodiment 1 of the present invention will not be described again.

[0165] Figure 20 This is a top view of the piezoelectric device according to Embodiment 2 of the present invention. Figure 20As shown, in the piezoelectric device 200 of Embodiment 2 of the present invention, the connecting portion 130 connects a pair of adjacent beam portions 220 of a plurality of beam portions 220 to each other. A first slit 141 and a second slit 142 are provided between the pair of beam portions 220. The first slit 141 is formed by a portion of a pair of adjacent end edges of the pair of beam portions 220. The second slit 142 is formed at a different location from the first slit 141 by another portion of a pair of adjacent end edges of the pair of beam portions 220. The connecting portion 130 is located at least between the first slit 141 and the second slit 142. The connecting portion 130 has a first end portion 133A, a second end portion 133B, a bridging portion 131, a first connecting portion 132A, and a second connecting portion 132B. The connecting portion 130 is connected to one of the pair of beam portions 120 at the first end portion 133A. The connecting portion 130 is connected to another of the pair of beam portions 120 at its second end 133B. The second end 133B is opposite to the first end 133A in the direction in which the pair of beam portions 220 are arranged. The bridging portion 131 is folded back between the pair of beam portions 220 and is provided for connecting the pair of beam portions 120 to each other. The first connecting portion 132A is connected to the portion of the bridging portion 131 located on one side of the pair of beam portions 220. The second connecting portion 132B is connected to the portion of the bridging portion 131 located on the other side of the pair of beam portions 220. The second connecting portion 132B is located along the first connecting portion 132A. The connecting portion 130 has only one first end 133A. The connecting portion 130 has only one second end 133B. The first end 133A and the second end 133B are respectively located closer to the respective top ends 122 of the pair of beam portions 220 than to the fixed ends 121. Therefore, it is possible to increase the resonant frequency while suppressing the vibration of each of the multiple beams 220, and reduce the vibration deviation.

[0166] Furthermore, the piezoelectric device 200 of Embodiment 2 of the present invention includes two beam portions 220, which are multiple beam portions 220. The two beam portions 220 are located at positions opposite each other at their respective top ends 122. The first slit 141 and the second slit 142 are respectively located between the respective top ends 122 of the two beam portions 220. Thus, in the piezoelectric device 200 including the two beam portions 220, the connecting portion 130 can also reduce the vibration deviation of the two beam portions 220 while suppressing the increase of the resonant frequency when each of the two beam portions 220 vibrates.

[0167] Furthermore, in this embodiment, more specifically, the first slit 141 is formed in a manner that is partially adjacent to the top end portion 122 of each of the two beam portions 220. The second slit 142 is formed at a different location from the first slit 141 in a manner that is partially adjacent to the top end portion 122 of each of the two beam portions 220.

[0168] In this embodiment, the two beam portions 220 extend in the same direction as each other. Specifically, the first slit 141 and the second slit 142 extend in directions intersecting the respective extending directions of the two beam portions 220, and more specifically, in directions orthogonal to the respective extending directions of the two beam portions 220. Thus, in this embodiment, the connecting portion 130 can also be provided with a simple structure.

[0169] In this embodiment, the fixed end portion 121 and the top end portion 122 are respectively located in an orthogonal direction to the aforementioned extending direction of each of the two beam portions 220. This simplifies the external shape of the two beam portions 220. Furthermore, specifically, each of the two beam portions 220 has a generally rectangular shape when viewed from the aforementioned stacking direction. Each of the two beam portions 220 has a pair of side ends 223. The pair of side ends 223 respectively connect the end of the fixed end portion 121 to the end of the top end portion 122. The pair of side ends 223 are respectively located at a position separate from the base portion 110.

[0170] The piezoelectric device 200 of this embodiment also includes an added connecting portion 230. The added connecting portion 230 is arranged in a manner symmetrical about the imaginary center point between the top ends 122 of each of the two beam portions 220 and the connecting portion 130. The added connecting portion 230 has the same structure as the connecting portion 130. Each component constituting the added connecting portion 230 is arranged in a manner symmetrical about the aforementioned imaginary center point between the top ends 122 and the components constituting the connecting portion 130.

[0171] Moreover, such as Figure 20 As shown, an additional first slit 241 and an additional peripheral slit 243 are provided between the two beam portions 220. The additional first slit 241 is arranged symmetrically with respect to the aforementioned imaginary center point between the top portions 122 and the first slit 141. The additional first slit 241 extends in the same direction as the first slit 141 and the second slit 142. Specifically, when viewed from the aforementioned stacking direction, the additional first slit 241, the first slit 141, and the second slit 142 are located on the same imaginary straight line. The additional peripheral slit 243 is arranged symmetrically with respect to the aforementioned imaginary center point between the top portions 122 and the peripheral slit 143.

[0172] In this embodiment, the relative positions of the added first slit 241, second slit 142, and added peripheral slit 243 relative to the added connecting portion 230 are the same as the relative positions of the first slit 141, second slit 142, and peripheral slit 143 relative to the connecting portion 130.

[0173] Furthermore, in this embodiment, the axial direction of the polarization axis of the single-crystal piezoelectric material constituting the piezoelectric layer is oriented in a specific direction. That is, the axial direction of the imaginary axis when the polarization axis of the single-crystal piezoelectric material is projected from the aforementioned stacking direction onto an imaginary plane orthogonal to the aforementioned stacking direction is also oriented in a specific direction. In this embodiment, the angles formed by the extension directions of each of the two beam portions 220 and the axial direction of the aforementioned imaginary axis when viewed from the aforementioned stacking direction are both 0 degrees or more and 5 degrees or less, 85 degrees or more and 95 degrees or less, or 175 degrees or more and less than 180 degrees. However, in this embodiment, the axial directions of the polarization axis of the single-crystal piezoelectric material and the aforementioned imaginary axis are not limited to the aforementioned specific directions.

[0174] Furthermore, in this embodiment, the single-crystal piezoelectric material has a polarization axis, thus generating thermal stress in the two beam portions 220. Consequently, the two beam portions 220 may warp when viewed from an orthogonal direction orthogonal to the aforementioned stacking direction. Hereinafter, examples of deformations in which the multiple beam portions 220 warp respectively will be described.

[0175] Figure 21 This is a top view of the piezoelectric device of the first variation of Embodiment 2 of the present invention. Figure 22 Observe from the direction of the arrow in line XII-XII Figure 21 A partial cross-sectional view obtained from the piezoelectric device shown.

[0176] like Figure 21 As shown, in the piezoelectric device 200a of the first modified embodiment 2 of the present invention, when viewed from the stacking direction, the axial direction of the imaginary axis of the single crystal piezoelectric body forms an angle of 45 degrees with the first slit 141, the second slit 142 and the added first slit 241, respectively.

[0177] Therefore, in this modified example, the length L1 of the imaginary shaft along its axial direction, from the center of the connecting portion 130 to the opposite end of one of the two beam portions 220 when viewed from the stacking direction, is different from the length L2 of the imaginary shaft along its axial direction to the opposite end of the other beam portion 220. Furthermore, the end of one of the beam portions 220 along its axial direction, located opposite to the center of the connecting portion 130, is not a fixed end 121. On the other hand, the end of the other beam portion 220 along its axial direction, located opposite to the center of the connecting portion 130, is a fixed end 121. Therefore, when thermal stress is applied to the multiple beam portions 220, the two beam portions 220 warp in different ways near the connecting portion 130.

[0178] Furthermore, in the piezoelectric device 200a of this modified example, thermal stress is applied to the multiple beams 220. As a result, such as Figure 22 As shown, when the piezoelectric device 200a is not driven, the ends of the two beam portions 220 near the center of the connecting portion 130 are located at different positions relative to each other in the aforementioned stacking direction.

[0179] Figure 23 This is a top view of the piezoelectric device of the first variation of Embodiment 3 of the present invention. Figure 24 Observe from the direction of the arrow in line XXIV-XXIV. Figure 23 A partial cross-sectional view obtained from the piezoelectric device shown.

[0180] like Figure 23 As shown, in the piezoelectric device 200b of the second variation of Embodiment 2 of the present invention, when viewed from the above-mentioned stacking direction, the axial direction of the imaginary axis of the single crystal piezoelectric body forms an angle of 0 degrees or 90 degrees with the first slit 141, the second slit 142 and the added first slit 241, respectively.

[0181] Therefore, in this modified example, the length L1 of the imaginary axis, viewed from the stacking direction, from the center of the connecting portion 130 to the opposite end of one of the two beam portions 220, and the length L2 of the imaginary axis, viewed from the center of the connecting portion 130 to the opposite end of the other beam portion 220, are the same. Furthermore, the distance from the end near the center of the connecting portion 130 to the fixed end 121 of one of the beam portions 220, viewed from the stacking direction, and the distance from the end near the center of the connecting portion 130 to the fixed end 121 of the other beam portion 220, are the same.

[0182] Furthermore, in the piezoelectric device 200b of this modified example, by applying thermal stress to the two beams 220, the two beams 220 warp respectively. As a result, as Figure 24 As shown, when the piezoelectric device 200b is not driven, the ends of the two beam portions 220 near the center of the connecting portion 130 are located at approximately the same position in the aforementioned stacking direction. Thus, in this modified example, even if multiple beam portions 220 warp due to thermal stress, since a pair of beam portions 220 deform in the same way in the aforementioned stacking direction, damage to the connecting portion 130, and in particular, damage to the bridging portion 131, can be suppressed.

[0183] As described above, by comparing the piezoelectric device 200a of the first modification of Embodiment 2 of the present invention with the piezoelectric device 200b of the second modification, it can be seen that in Embodiment 2 of the present invention, when viewed from the stacking direction, if the angle between the axial direction of the imaginary axis and the respective extension directions of the first slit 141 and the second slit 142 is 45 degrees or 135 degrees, the closer the angle is to 0 degrees or 90 degrees, the more effectively the difference in displacement of the two beam portions 220 caused by thermal stress can be suppressed. Similarly, in Embodiment 2 of the present invention, it can be seen that when viewed from the stacking direction, if the angle between the axial direction of the imaginary axis and the respective extension directions of the two beam portions 220 is 45 degrees or 135 degrees, the closer the angle is to 0 degrees or 90 degrees, the more effectively the difference in displacement of the two beam portions in the stacking direction caused by thermal stress can be suppressed.

[0184] (Implementation Method 3)

[0185] The piezoelectric device according to Embodiment 3 of the present invention will be described below. In the piezoelectric device of Embodiment 3 of the present invention, the structure of each slit differs from that of the piezoelectric device 200 of Embodiment 2 of the present invention. Therefore, the same structure as that of the piezoelectric device 200 of Embodiment 2 of the present invention will not be described again.

[0186] Figure 25 This is a top view of the piezoelectric device according to Embodiment 3 of the present invention. Figure 25 As shown, the piezoelectric device 300 of Embodiment 3 of the present invention includes only one connecting portion 330. That is, in the piezoelectric device 300 of Embodiment 3 of the present invention, the added first slit and the added peripheral slit provided in the piezoelectric device 200 of Embodiment 2 of the present invention are not provided.

[0187] In the piezoelectric device 300 of Embodiment 3 of the present invention, the connecting portion 330 connects a pair of adjacent beam portions 220 of a plurality of beam portions 220 to each other. A first slit 141 and a second slit 142 are provided between the pair of beam portions 220. The first slit 141 is formed by a portion of a pair of adjacent end edges of the pair of beam portions 220. The second slit 142 is formed at a different location from the first slit 141 by another portion of a pair of adjacent end edges of the pair of beam portions 220. The connecting portion 330 is located at least between the first slit 141 and the second slit 142. The connecting portion 330 has a first end portion 133A, a second end portion 133B, a bridging portion 131, a first connecting portion 132A, and a second connecting portion 132B. The connecting portion 330 is connected to one of the pair of beam portions 220 at the first end portion 133A. The connecting portion 330 is connected to another of the pair of beam portions 220 at its second end 133B. The second end 133B is opposite to the first end 133A in the direction in which the pair of beam portions 220 are arranged. The bridging portion 131 is folded back between the pair of beam portions 220 and is provided for connecting the pair of beam portions 220 to each other. The first connecting portion 132A is connected to the portion of the bridging portion 131 located on one side of the pair of beam portions 220. The second connecting portion 132B is connected to the portion of the bridging portion 131 located on the other side of the pair of beam portions 220. The second connecting portion 132B is located along the first connecting portion 132A. The connecting portion 330 has only one first end 133A. The connecting portion 330 has only one second end 133B. The first end 133A and the second end 133B are respectively located closer to the top end 122 of the pair of beam portions 220 than to the fixed end 121. Therefore, it is possible to increase the resonant frequency when suppressing the vibration of each of the multiple beams 220, while reducing the vibration deviation of the multiple beams 220.

[0188] (Implementation Method 4)

[0189] The piezoelectric device according to Embodiment 4 of the present invention will now be described. The piezoelectric device of Embodiment 4 differs from the piezoelectric device 100 of Embodiment 1 of the present invention in that it specifies the dimensional relationship between the extension length, minimum width, and thickness of the first connecting portion and the second connecting portion. Therefore, the same structure as the piezoelectric device 100 of Embodiment 1 of the present invention will not be described again.

[0190] Figure 26 This is a top view of the piezoelectric device according to Embodiment 4 of the present invention. Figure 27 Observe from the direction of the arrow in line XXVII-XXVII. Figure 26 The cross-sectional view obtained from the piezoelectric device. Figure 28 This is a partial top view showing the structure of the connection portion of the piezoelectric device according to Embodiment 4 of the present invention. Figure 27 In the middle, for easier observation, the layers are shown in a thicker diagram.

[0191] like Figures 26-28 As shown, the piezoelectric device 400 of Embodiment 4 of the present invention includes a base 110, four beam portions 120, and four connecting portions 430. The fixed ends 121 of the four beam portions 120 are located in a square shape when viewed from the above-mentioned stacking direction. Figure 26 The dimension M of the shortest distance M between the opposing fixed ends 121 of the four beam portions 120 when viewed from the above-mentioned stacking direction is the dimension measured along a straight line passing through the fixed end 121 of the beam portion 120 with one of the opposing fixed ends 121 between them and the top end portion 122 in the shortest manner.

[0192] The connecting part 430 connects a pair of adjacent beams 120 among the four beams 120. The connecting part 430 has a bridging part 131, a first connecting part 132A and a second connecting part 132B.

[0193] In this embodiment, the first connecting portion 132A, the second connecting portion 132B, and the bridging portion 131 each have a constant width and extend in a straight line. The minimum width W of the first connecting portion 132A and the second connecting portion 132B is the same as the maximum width a of the bridging portion 131.

[0194] In the piezoelectric device 400, if the force generated by the connecting part 430 connecting the beams 120 to each other becomes too weak, a complex vibration mode is easily generated. This ease of generation can be quantified by the resonant frequency of the complex vibration mode and the resonant frequency of the basic vibration mode. The more separated these resonant frequencies are, the more difficult it is to generate a complex vibration mode.

[0195] Here, the resonant frequency of the composite vibration mode varies according to the ratio of the out-of-plane bending stiffness of the four beams 120 and the connecting part 430. In each of the beams 120 and the connecting part 430, the bending stiffness mainly depends on parameters such as thickness, length, and the hardness and density of the structural material.

[0196] The four beam portions 120 and the connecting portion 430 differ from each other in that the beam portions 120 include the first electrode layer 12 while the connecting portion 430 does not. However, since they have approximately the same stacked structure, their thickness, hardness, and density are approximately the same. The aforementioned bending stiffness varies significantly depending on the difference in their lengths. That is, by adjusting the ratio of the extension length L of the first connecting portion 132A and the second connecting portion 132B to the shortest distance M between the fixed ends 121, the resonant frequency of the composite vibration mode can be changed.

[0197] Typically, in a sound device utilizing the bending vibration of a relatively thin beam portion 120 as described in this embodiment, the Q value at resonance is suppressed to around 10 due to the load generated by air resistance. Therefore, for example, even when the piezoelectric device 400 is used at a frequency offset by ±5% from the resonant frequency, more than half the energy at resonance can be input to the piezoelectric device 400, thus expanding the usable frequency range. In particular, when the piezoelectric device 400 is mass-produced using MEMS (Micro Electro Mechanical Systems) processing, a deviation of approximately ±5% in the resonant frequency sometimes occurs depending on the processing accuracy of the MEMS. However, in a piezoelectric device 400 with a wide usable frequency range as described above, significant deviations in the characteristics of the piezoelectric device 400 can be suppressed.

[0198] However, when a resonant frequency of a composite vibration mode exists within the aforementioned usable frequency band, the energy input to the piezoelectric device 400 is absorbed as the vibration energy of the composite vibration mode, not as the vibration energy of the fundamental vibration mode. In this case, the conversion efficiency of the piezoelectric device 400 decreases, and the Q value of the composite vibration mode is higher, thus the reverberation after the piezoelectric device 400 stops operating becomes longer.

[0199] In view of this problem, it is preferable that the resonant frequency of the composite vibration mode is at least 5% higher than the resonant frequency of the basic vibration mode. Therefore, simulation analysis is performed by changing the minimum width W of each of the first connecting parts 132A and the second connecting parts 132B in relation to the ratio of the dimension of the extension length L of each of the first connecting parts 132A and the second connecting parts 132B to the dimension of the shortest distance M between the fixed ends 121, and the ratio of the difference between the secondary and primary resonant frequencies of each of the four beam parts 120 to the primary resonant frequency. The aforementioned primary resonant frequency corresponds to the resonant frequency of the basic vibration mode, and the aforementioned secondary resonant frequency corresponds to the resonant frequency of the composite vibration mode.

[0200] As simulation analysis conditions, in the piezoelectric device 400 of this embodiment, the shortest distance M between the fixed ends 121 is set to 800 μm, the thickness of the piezoelectric layer 11 is set to 1 μm, and the thickness of the support layer 14 is set to 2 μm. That is, the minimum distance M between the fixed ends 121 is set to 800 μm, the thickness of the piezoelectric layer 11 is set to 1 μm, and the thickness of the support layer 14 is set to 2 μm. Figure 27 The thickness T shown is set to 3 μm. This thickness T corresponds to the thickness of the first connecting part 132A and the second connecting part 132B in the aforementioned stacking direction. The minimum width W of the first connecting part 132A and the second connecting part 132B is set to three values: 10 μm, 15 μm, and 20 μm.

[0201] Figure 29 These are graphs representing the results of simulation analysis. Figure 29In the diagram, the vertical axis represents the percentage (%) of the difference between the secondary resonance frequency fr2 and the primary resonance frequency fr1 of each of the four beam sections 120 relative to the primary resonance frequency fr1. The horizontal axis represents the percentage (%) of the extension length L of each of the first connecting section 132A and the second connecting section 132B relative to the shortest distance M between the fixed ends 121. Furthermore, solid lines represent data where the minimum width W of each of the first connecting section 132A and the second connecting section 132B is 10 μm; dashed lines represent data where the minimum width W of each of the first connecting section 132A and the second connecting section 132B is 15 μm; and dashed lines represent data where the minimum width W of each of the first connecting section 132A and the second connecting section 132B is 20 μm. Moreover, dashed lines represent a baseline where the percentage of the difference between the secondary resonance frequency fr2 and the primary resonance frequency fr1 of each of the four beam sections is 5%.

[0202] like Figure 29 As shown, it is confirmed that as the ratio of the extension length L of the first connecting part 132A and the second connecting part 132B to the shortest distance M between the fixed ends 121 [(L / M)×100(%)] increases, the ratio of the difference between the secondary resonance frequency fr2 and the primary resonance frequency fr1 of the four beam parts 120 to the primary resonance frequency fr1 [(fr2-fr1) / fr1)×100(%)] tends to decrease.

[0203] When the minimum width W of each of the first connecting part 132A and the second connecting part 132B is any one of 10μm, 15μm and 20μm, and the ratio of the dimension of the extension length L of each of the first connecting part 132A and the second connecting part 132B to the dimension of the shortest distance M between the fixed ends 121 [(L / M)×100(%)] is less than 30%, the ratio of the difference between the secondary resonance frequency fr2 and the primary resonance frequency fr1 of each of the four beam parts 120 to the primary resonance frequency fr1 [(fr2-fr1) / fr1)×100(%)] is more than 5%.

[0204] Therefore, in this embodiment, when viewed from the aforementioned stacking direction, the dimensions of the extension length L of each of the first connecting portion 132A and the second connecting portion 132B are in proportion to the dimensions of the shortest distance M between the opposing fixed ends 121 of the four beam portions 120, which is less than 30%. As a result, it is difficult to generate complex vibration modes, and the reduction in the conversion efficiency of the piezoelectric device 400 and the increase in reverberation after the piezoelectric device 400 stops driving are suppressed.

[0205] As described above, the resonant frequency of the composite vibration mode varies according to the ratio of the out-of-plane bending stiffness of the four beam portions 120 and the connecting portion 430. Assuming that the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is smaller than the thickness T of each of the first connecting portion 132A and the second connecting portion 132B in the aforementioned stacking direction, the in-plane bending stiffness of the four beam portions 120 and the connecting portion 430 will be lower than the out-of-plane bending stiffness. In this case, the resonant frequency of the composite vibration mode is close to the resonant frequency of the basic vibration mode, and it is sometimes difficult to ensure that [(fr2-fr1) / fr1]×100(%) is above 5%.

[0206] Therefore, in this embodiment, the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is larger than the thickness T of each of the first connecting portion 132A and the second connecting portion 132B in the aforementioned stacking direction. As a result, it is difficult to generate composite vibration modes, and the reduction in the conversion efficiency of the piezoelectric device 400 and the lengthening of the reverberation after the piezoelectric device 400 stops driving can be suppressed.

[0207] Furthermore, the shape of the connection portion 430, which can be defined by the parameters described above, is not limited to the shape described above. Here, the shape of the connection portion in a modified example, in which the parameters described above can be applied, will be described. In the following description of the modified examples, the same structure as the connection portion 430 of the piezoelectric device 400 of Embodiment 4 of the present invention will not be described again.

[0208] Figure 30 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the first modified example of Embodiment 4 of the present invention. Figure 30 As shown, in the first variation of Embodiment 4 of the present invention, the bridging portion 131 of the connecting portion 430a has a semi-circular shape with a radius of a centered on the top end of the second slit 142. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is the same as the maximum width a of the bridging portion 131.

[0209] Figure 31 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the second modification of Embodiment 4 of the present invention. Figure 31As shown, in the second variation of Embodiment 4 of the present invention, the first connecting portion 132A, the second connecting portion 132B, and the bridging portion 131 of the connecting portion 430b each have a constant width and extend in a straight line. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is smaller than the maximum width a of the bridging portion 131. Furthermore, the maximum width a of the bridging portion 131 is less than twice the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0210] Figure 32 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the third variation of Embodiment 4 of the present invention. Figure 32 As shown, in the third variation of Embodiment 4 of the present invention, the bridging portion 131 of the connecting portion 430c has a semi-circular shape with a radius of a centered on the top end of the second slit 142. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is smaller than the maximum width a of the bridging portion 131. Furthermore, the maximum width a of the bridging portion 131 is less than twice the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0211] Figure 33 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the fourth variation of Embodiment 4 of the present invention. Figure 33 As shown, in the fourth variation of Embodiment 4 of the present invention, the bridging portions of the first connecting portion 132A and the second connecting portion 132B of the connecting portion 430d, as well as the bridging portion 131, each have an imaginary square shape with a length of 2a along one side centered on the top end of the second slit 142. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is smaller than the maximum width a of the bridging portion 131. Furthermore, the maximum width a of the bridging portion 131 is less than twice the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0212] Figure 34 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the fifth modification of Embodiment 4 of the present invention. Figure 34As shown, in the fifth variation of Embodiment 4 of the present invention, the bridging portions of the first connecting portion 132A and the second connecting portion 132B of the connecting portion 430e, as well as the bridging portion 131, each have the shape of an imaginary circle with radius a centered at the top end of the second slit 142. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is smaller than the maximum width a of the bridging portion 131. Furthermore, the maximum width a of the bridging portion 131 is less than twice the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0213] Figure 35 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the sixth variation of Embodiment 4 of the present invention. Figure 35 As shown, in the sixth variation of Embodiment 4 of the present invention, a circular opening 142r with a diameter r is formed at the top of the second slit 142. The diameter r is larger than the width of the second slit 142, and is less than or equal to the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B. The bridging portions of the first connecting portion 132A and the second connecting portion 132B of the connecting portion 430f, as well as the bridging portion 131, each have an imaginary square shape with a length of (2a+r) along one side centered on the center of the opening 142r. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is less than or equal to the maximum width a of the bridging portion 131. Furthermore, the maximum width a of the bridging portion 131 is less than or equal to twice the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0214] Figure 36 This is a partial top view showing the shape of the connection portion of the piezoelectric device in the seventh modification of Embodiment 4 of the present invention. Figure 36 As shown, in the sixth variation of Embodiment 4 of the present invention, a circular opening 142r with a diameter r is formed at the top of the second slit 142. The diameter r is larger than the width of the second slit 142, and is less than or equal to the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B. The bridging portions of the first connecting portion 132A and the second connecting portion 132B of the connecting portion 430g, as well as the bridging portion 131, each have a shape with a radius of (a+r / 2) centered on the center of the opening 142r. The minimum width W of each of the first connecting portion 132A and the second connecting portion 132B is less than or equal to the maximum width a of the bridging portion 131. Furthermore, the maximum width a of the bridging portion 131 is less than or equal to twice the minimum width W of each of the first connecting portion 132A and the second connecting portion 132B.

[0215] In the above description of the embodiments, the combinable structures can also be combined with each other.

[0216] The embodiments disclosed herein should be considered illustrative in all respects and not limiting. The scope of the invention is defined by the claims rather than by the foregoing description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0217] Explanation of reference numerals in the attached figures

[0218] 10. Multiple layers; 11. Piezoelectric layer; 11a. Piezoelectric single crystal substrate; 12. First electrode layer; 13. Second electrode layer; 14. Support layer; 14a. First support portion; 14b. Second support portion; 15. Substrate layer; 15a. First substrate layer; 15b. Second substrate layer; 16. Laminated structure; 17. Groove portion; 18. Recessed portion; 20. First connecting electrode layer; 30. Second connecting electrode layer; 100, 100a, 100b, 100c, 200, 200a, 200b, 300, 400. Piezoelectric device; 101. Opening portion; 110. Base portion; 120, 2 20, 320, Beam section; 121, Fixed end; 122, Top end; 130, 330, 430, 430a, 430b, 430c, 430d, 430e, 430f, 430g, Connecting part; 131, Bridging part; 132A, First connecting part; 132B, Second connecting part; 133A, First end; 133B, Second end; 141, First slit; 142, Second slit; 142r, Opening; 143, Outer peripheral slit; 223, Side end; 230, Added connecting part; 241, Added first slit; 243, Added outer peripheral slit.

Claims

1. A piezoelectric device, wherein, The piezoelectric device includes: Base; Multiple beam portions, each having a fixed end connected to the base and a top end located on the side opposite to the fixed end, extending from the fixed end toward the top end; and A connecting portion that connects a pair of adjacent beams among the plurality of beam portions. The multiple beams are piezoelectric vibrating parts comprising multiple layers. A first slit is provided between the pair of beams by a portion of a pair of adjacent end edges of the pair of beams, and a second slit is provided at a different location by another portion of a pair of adjacent end edges of the pair of beams. The connecting portion is located at least between the first slit and the second slit. The connecting portion has: a first end portion connected to one of the pair of beam portions; a second end portion connected to the other of the pair of beam portions, and opposite to the first end portion in the direction in which the pair of beam portions are arranged; a bridging portion folded back between the pair of beam portions and provided for connecting the pair of beam portions to each other; a first connecting portion connected to the portion of the bridging portion located on one side of the pair of beam portions; and a second connecting portion connected to the portion of the bridging portion located on the other side of the pair of beam portions, and located along the position of the first connecting portion. The connecting portion has only one first end and only one second end. The first end and the second end are respectively located at a distance from the top end of the pair of beams that is closer than the distance from the fixed end. An outer peripheral slit is formed between the pair of beams by the outer peripheral edge of the folded-back portion of the connecting part at the bridging part and the respective end edge of the pair of beams. The first slit is connected to the outer peripheral slit. The second slit is located on the inner circumference of the folded-back portion of the connecting part at the bridging section.

2. The piezoelectric device according to claim 1, wherein, The first connecting portion extends along the second slit, starting from the first end. The second connecting portion extends along the second slit, starting from the second end portion.

3. The piezoelectric device according to claim 2, wherein, The first connecting part is directly connected to the bridging part on the side opposite to the first end side. The second connecting part is directly connected to the bridging part on the side opposite to the second end side.

4. The piezoelectric device according to claim 2 or 3, wherein, When viewed from the stacking direction of the plurality of layers, the extension length of each of the first connecting portion and the second connecting portion is larger than the minimum width of each of the first connecting portion and the second connecting portion in a direction orthogonal to the path extending from the first connecting portion and the second connecting portion toward the connection portion of the bridging portion.

5. The piezoelectric device according to claim 2 or 3, wherein, When viewed from the stacking direction of the multiple layers, the length of the path extending from the first connecting portion and the second connecting portion toward the connection portion with the bridging portion, i.e., the extension length of each of the first connecting portion and the second connecting portion, is larger than the shortest length from the connecting portion to the top portion.

6. The piezoelectric device according to claim 2 or 3, wherein, When viewed from the stacking direction of the multiple layers, the length of the path extending from the first connecting part and the second connecting part toward the connection part with the bridging part, i.e., the extension length of each of the first connecting part and the second connecting part, is larger than the maximum width of the bridging part in the direction orthogonal to the direction opposite to the pair of beams.

7. The piezoelectric device according to claim 2 or 3, wherein, When viewed from the stacking direction of the multiple layers, the maximum width of the bridging portion in a direction orthogonal to the direction in which the pair of beams are opposite to each other is larger than the minimum width of each of the first and second connecting portions in a direction orthogonal to the path extending from the first connecting portion and the second connecting portion toward the connection portion of the bridging portion.

8. The piezoelectric device according to claim 1, wherein, The first slit is located on the fixed end side of each of the pair of beams relative to the bridging portion. The second slit is located on the top end side of each of the pair of beams relative to the bridging portion.

9. The piezoelectric device according to any one of claims 1 to 3, wherein, The piezoelectric device includes four beam sections as the plurality of beam sections and four connecting sections as the connecting sections. The four beams are located along the same plane. The four beams extend toward an imaginary center point and are adjacent to each other circumferentially around the imaginary center point. The four connecting parts are located between adjacent beams in the four beam sections and connect adjacent pairs of beam sections to each other.

10. The piezoelectric device according to any one of claims 1 to 3, wherein, The piezoelectric device includes two beams that serve as the plurality of beams. The two beam sections are located at their respective top ends facing each other. The first slit and the second slit are respectively located between the top ends of the two beams.

11. The piezoelectric device according to claim 10, wherein, The two beams extend in the same direction as each other. The first slit and the second slit extend in directions orthogonal to the respective extension directions of the two beams.

12. The piezoelectric device according to claim 11, wherein, The fixed end and the top end are respectively located in a direction orthogonal to the respective extension directions of the two beams.

13. The piezoelectric device according to any one of claims 1 to 3, wherein, The plurality of layers have: The piezoelectric layer is composed of single-crystal piezoelectric material; A first electrode layer, disposed on one side of the piezoelectric layer in the stacking direction of the plurality of layers; and A second electrode layer is disposed on the other side of the piezoelectric layer, at least partially opposite to the first electrode layer, separated by the piezoelectric layer. When the polarization axis of the single-crystal piezoelectric is projected from the stacking direction onto an imaginary plane orthogonal to the stacking direction, the axial direction of the imaginary axis extends in the same direction in any of the plurality of beams, and when viewed from the stacking direction, the angle formed with the respective extension directions of the first slit and the second slit is not 45 degrees.

14. The piezoelectric device according to claim 13, wherein, The axial direction of the imaginary axis, when viewed from the stacking direction, forms an angle of 0 degrees or more and less than 5 degrees with the respective extension directions of the first slit and the second slit, 85 degrees or more and less than 95 degrees, or 175 degrees or more and less than 180 degrees.

15. The piezoelectric device according to claim 13, wherein, When each beam portion of the pair of beam portions is viewed from the first slit side and the second slit side, the pair of beam portions are tilted in either direction of the stacking direction.

16. The piezoelectric device according to claim 13, wherein, When viewed from the stacking direction, the angle between the extension direction of each of the plurality of beams and the axial direction of the imaginary axis when viewed from the stacking direction is either 40 degrees or more and less than 50 degrees or 130 degrees or more and less than 140 degrees.

17. The piezoelectric device according to claim 13, wherein, The piezoelectric layer is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

18. The piezoelectric device according to claim 9, wherein, The fixed ends of the four beams are located in a square shape when viewed from the stacking direction of the multiple layers. When viewed from the stacking direction, the dimensions of the extension lengths of the first connecting portion and the second connecting portion are in proportion to the dimensions of the shortest distance between the opposing fixed ends of the four beam portions.

19. The piezoelectric device according to any one of claims 1 to 3, wherein, The minimum width of each of the first connecting portion and the second connecting portion is larger than the thickness of each of the plurality of layers in the stacking direction.

20. A piezoelectric device, wherein, The piezoelectric device includes: Base; Multiple beam portions, each having a fixed end connected to the base and a top end located on the side opposite to the fixed end, extending from the fixed end toward the top end; and A connecting portion that connects a pair of adjacent beams among the plurality of beam portions. The multiple beams are piezoelectric vibrating parts comprising multiple layers. A first slit is provided between the pair of beams by a portion of a pair of adjacent end edges of the pair of beams, and a second slit is provided at a different location by another portion of a pair of adjacent end edges of the pair of beams. The connecting portion is located at least between the first slit and the second slit. The connecting portion has: a first end portion connected to one of the pair of beam portions; a second end portion connected to the other of the pair of beam portions, and opposite to the first end portion in the direction in which the pair of beam portions are arranged; a bridging portion folded back between the pair of beam portions and provided for connecting the pair of beam portions to each other; a first connecting portion connected to the portion of the bridging portion located on one side of the pair of beam portions; and a second connecting portion connected to the portion of the bridging portion located on the other side of the pair of beam portions, and located along the position of the first connecting portion. The connecting portion has only one first end and only one second end. The first end and the second end are respectively located at a distance from the top end of the pair of beams that is closer than the distance from the fixed end. The first connecting portion extends along the second slit, starting from the first end. The second connecting portion extends along the second slit, starting from the second end portion.

21. The piezoelectric device according to claim 20, wherein, The first connecting part is directly connected to the bridging part on the side opposite to the first end side. The second connecting part is directly connected to the bridging part on the side opposite to the second end side.

22. The piezoelectric device according to claim 20 or 21, wherein, When viewed from the stacking direction of the plurality of layers, the extension length of each of the first connecting portion and the second connecting portion is larger than the minimum width of each of the first connecting portion and the second connecting portion in a direction orthogonal to the path extending from the first connecting portion and the second connecting portion toward the connection portion of the bridging portion.

23. The piezoelectric device according to claim 20 or 21, wherein, When viewed from the stacking direction of the multiple layers, the length of the path extending from the first connecting portion and the second connecting portion toward the connection portion with the bridging portion, i.e., the extension length of each of the first connecting portion and the second connecting portion, is larger than the shortest length from the connecting portion to the top portion.

24. The piezoelectric device according to claim 20 or 21, wherein, When viewed from the stacking direction of the multiple layers, the length of the path extending from the first connecting part and the second connecting part toward the connection part with the bridging part, i.e., the extension length of each of the first connecting part and the second connecting part, is larger than the maximum width of the bridging part in the direction orthogonal to the direction opposite to the pair of beams.

25. The piezoelectric device according to claim 20 or 21, wherein, When viewed from the stacking direction of the multiple layers, the maximum width of the bridging portion in a direction orthogonal to the direction in which the pair of beams are opposite to each other is larger than the minimum width of each of the first and second connecting portions in a direction orthogonal to the path extending from the first connecting portion and the second connecting portion toward the connection portion of the bridging portion.

26. The piezoelectric device according to claim 20, wherein, The first slit is located on the fixed end side of each of the pair of beams relative to the bridging portion. The second slit is located on the top end side of each of the pair of beams relative to the bridging portion.

27. The piezoelectric device according to claim 20 or 21, wherein, The piezoelectric device includes four beam sections as the plurality of beam sections and four connecting sections as the connecting sections. The four beams are located along the same plane. The four beams extend toward an imaginary center point and are adjacent to each other circumferentially around the imaginary center point. The four connecting parts are located between adjacent beams in the four beam sections and connect adjacent pairs of beam sections to each other.

28. The piezoelectric device according to claim 20 or 21, wherein, The piezoelectric device includes two beams that serve as the plurality of beams. The two beam sections are located at their respective top ends facing each other. The first slit and the second slit are respectively located between the top ends of the two beams.

29. The piezoelectric device according to claim 28, wherein, The two beams extend in the same direction as each other. The first slit and the second slit extend in directions orthogonal to the respective extension directions of the two beams.

30. The piezoelectric device according to claim 29, wherein, The fixed end and the top end are respectively located in a direction orthogonal to the respective extension directions of the two beams.

31. The piezoelectric device according to claim 20 or 21, wherein, The plurality of layers have: The piezoelectric layer is composed of single-crystal piezoelectric material; A first electrode layer, disposed on one side of the piezoelectric layer in the stacking direction of the plurality of layers; and A second electrode layer is disposed on the other side of the piezoelectric layer, at least partially opposite to the first electrode layer, separated by the piezoelectric layer. When the polarization axis of the single-crystal piezoelectric is projected from the stacking direction onto an imaginary plane orthogonal to the stacking direction, the axial direction of the imaginary axis extends in the same direction in any of the plurality of beams, and when viewed from the stacking direction, the angle formed with the respective extension directions of the first slit and the second slit is not 45 degrees.

32. The piezoelectric device according to claim 31, wherein, The axial direction of the imaginary axis, when viewed from the stacking direction, forms an angle of 0 degrees or more and less than 5 degrees with the respective extension directions of the first slit and the second slit, 85 degrees or more and less than 95 degrees, or 175 degrees or more and less than 180 degrees.

33. The piezoelectric device according to claim 31, wherein, When each beam portion of the pair of beam portions is viewed from the first slit side and the second slit side, the pair of beam portions are tilted in either direction of the stacking direction.

34. The piezoelectric device according to claim 31, wherein, When viewed from the stacking direction, the angle between the extension direction of each of the plurality of beams and the axial direction of the imaginary axis when viewed from the stacking direction is either 40 degrees or more and less than 50 degrees or 130 degrees or more and less than 140 degrees.

35. The piezoelectric device according to claim 31, wherein, The piezoelectric layer is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

36. The piezoelectric device according to claim 27, wherein, The fixed ends of the four beams are located in a square shape when viewed from the stacking direction of the multiple layers. When viewed from the stacking direction, the dimensions of the extension lengths of the first connecting portion and the second connecting portion are in proportion to the dimensions of the shortest distance between the opposing fixed ends of the four beam portions.

37. The piezoelectric device according to claim 20 or 21, wherein, The minimum width of each of the first connecting portion and the second connecting portion is larger than the thickness of each of the plurality of layers in the stacking direction.

38. A piezoelectric device, wherein, The piezoelectric device includes: Base; Multiple beam portions, each having a fixed end connected to the base and a top end located on the side opposite to the fixed end, extending from the fixed end toward the top end; and A connecting portion that connects a pair of adjacent beams among the plurality of beam portions. The multiple beams are piezoelectric vibrating parts comprising multiple layers. A first slit is provided between the pair of beams by a portion of a pair of adjacent end edges of the pair of beams, and a second slit is provided at a different location by another portion of a pair of adjacent end edges of the pair of beams. The connecting portion is located at least between the first slit and the second slit. The connecting portion has: a first end portion connected to one of the pair of beam portions; a second end portion connected to the other of the pair of beam portions, and opposite to the first end portion in the direction in which the pair of beam portions are arranged; a bridging portion folded back between the pair of beam portions and provided for connecting the pair of beam portions to each other; a first connecting portion connected to the portion of the bridging portion located on one side of the pair of beam portions; and a second connecting portion connected to the portion of the bridging portion located on the other side of the pair of beam portions, and located along the position of the first connecting portion. The connecting portion has only one first end and only one second end. The first end and the second end are respectively located at a distance from the top end of the pair of beams that is closer than the distance from the fixed end. The piezoelectric device includes four beam sections as the plurality of beam sections and four connecting sections as the connecting sections. The four beams are located along the same plane. The four beams extend toward an imaginary center point and are adjacent to each other circumferentially around the imaginary center point. The four connecting parts are located between adjacent beams in the four beam sections and connect adjacent pairs of beam sections to each other.

39. The piezoelectric device according to claim 38, wherein, The first slit is located on the fixed end side of each of the pair of beams relative to the bridging portion. The second slit is located on the top end side of each of the pair of beams relative to the bridging portion.

40. The piezoelectric device according to claim 38, wherein, The piezoelectric device includes two beams that serve as the plurality of beams. The two beam sections are located at their respective top ends facing each other. The first slit and the second slit are respectively located between the top ends of the two beams.

41. The piezoelectric device according to claim 40, wherein, The two beams extend in the same direction as each other. The first slit and the second slit extend in directions orthogonal to the respective extension directions of the two beams.

42. The piezoelectric device according to claim 41, wherein, The fixed end and the top end are respectively located in a direction orthogonal to the respective extension directions of the two beams.

43. The piezoelectric device according to any one of claims 38 to 42, wherein, The plurality of layers have: The piezoelectric layer is composed of single-crystal piezoelectric material; A first electrode layer, disposed on one side of the piezoelectric layer in the stacking direction of the plurality of layers; and A second electrode layer is disposed on the other side of the piezoelectric layer, at least partially opposite to the first electrode layer, separated by the piezoelectric layer. When the polarization axis of the single-crystal piezoelectric is projected from the stacking direction onto an imaginary plane orthogonal to the stacking direction, the axial direction of the imaginary axis extends in the same direction in any of the plurality of beams, and when viewed from the stacking direction, the angle formed with the respective extension directions of the first slit and the second slit is not 45 degrees.

44. The piezoelectric device according to claim 43, wherein, The axial direction of the imaginary axis, when viewed from the stacking direction, forms an angle of 0 degrees or more and less than 5 degrees with the respective extension directions of the first slit and the second slit, 85 degrees or more and less than 95 degrees, or 175 degrees or more and less than 180 degrees.

45. The piezoelectric device according to claim 43, wherein, When each beam portion of the pair of beam portions is viewed from the first slit side and the second slit side, the pair of beam portions are tilted in either direction of the stacking direction.

46. ​​The piezoelectric device according to claim 43, wherein, When viewed from the stacking direction, the angle between the extension direction of each of the plurality of beams and the axial direction of the imaginary axis when viewed from the stacking direction is either 40 degrees or more and less than 50 degrees or 130 degrees or more and less than 140 degrees.

47. The piezoelectric device according to claim 43, wherein, The piezoelectric layer is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

48. The piezoelectric device according to claim 38 or 39, wherein, The fixed ends of the four beams are located in a square shape when viewed from the stacking direction of the multiple layers. When viewed from the stacking direction, the dimensions of the extension lengths of the first connecting portion and the second connecting portion are in proportion to the dimensions of the shortest distance between the opposing fixed ends of the four beam portions.

49. The piezoelectric device according to any one of claims 38 to 42, wherein, The minimum width of each of the first connecting portion and the second connecting portion is larger than the thickness of each of the plurality of layers in the stacking direction.

50. A piezoelectric device, wherein, The piezoelectric device includes: Base; Multiple beam portions, each having a fixed end connected to the base and a top end located on the side opposite to the fixed end, extending from the fixed end toward the top end; and A connecting portion that connects a pair of adjacent beams among the plurality of beam portions. The multiple beams are piezoelectric vibrating parts comprising multiple layers. A first slit is provided between the pair of beams by a portion of a pair of adjacent end edges of the pair of beams, and a second slit is provided at a different location by another portion of a pair of adjacent end edges of the pair of beams. The connecting portion is located at least between the first slit and the second slit. The connecting portion has: a first end portion connected to one of the pair of beam portions; a second end portion connected to the other of the pair of beam portions, and opposite to the first end portion in the direction in which the pair of beam portions are arranged; a bridging portion folded back between the pair of beam portions and provided for connecting the pair of beam portions to each other; a first connecting portion connected to the portion of the bridging portion located on one side of the pair of beam portions; and a second connecting portion connected to the portion of the bridging portion located on the other side of the pair of beam portions, and located along the position of the first connecting portion. The connecting portion has only one first end and only one second end. The first end and the second end are respectively located at a distance from the top end of the pair of beams that is closer than the distance from the fixed end. The plurality of layers have: The piezoelectric layer is composed of single-crystal piezoelectric material; A first electrode layer, disposed on one side of the piezoelectric layer in the stacking direction of the plurality of layers; and A second electrode layer is disposed on the other side of the piezoelectric layer, at least partially opposite to the first electrode layer, separated by the piezoelectric layer. When the polarization axis of the single-crystal piezoelectric is projected from the stacking direction onto an imaginary plane orthogonal to the stacking direction, the axial direction of the imaginary axis extends in the same direction in any of the plurality of beams, and when viewed from the stacking direction, the angle formed with the respective extension directions of the first slit and the second slit is not 45 degrees.

51. The piezoelectric device according to claim 50, wherein, The first slit is located on the fixed end side of each of the pair of beams relative to the bridging portion. The second slit is located on the top end side of each of the pair of beams relative to the bridging portion.

52. The piezoelectric device according to claim 50, wherein, The piezoelectric device includes two beams that serve as the plurality of beams. The two beam sections are located at their respective top ends facing each other. The first slit and the second slit are respectively located between the top ends of the two beams.

53. The piezoelectric device according to claim 52, wherein, The two beams extend in the same direction as each other. The first slit and the second slit extend in directions orthogonal to the respective extension directions of the two beams.

54. The piezoelectric device according to claim 53, wherein, The fixed end and the top end are respectively located in a direction orthogonal to the respective extension directions of the two beams.

55. The piezoelectric device according to any one of claims 50 to 54, wherein, The axial direction of the imaginary axis, when viewed from the stacking direction, forms an angle of 0 degrees or more and less than 5 degrees with the respective extension directions of the first slit and the second slit, 85 degrees or more and less than 95 degrees, or 175 degrees or more and less than 180 degrees.

56. The piezoelectric device according to any one of claims 50 to 54, wherein, When each beam portion of the pair of beam portions is viewed from the first slit side and the second slit side, the pair of beam portions are tilted in either direction of the stacking direction.

57. The piezoelectric device according to any one of claims 50 to 54, wherein, When viewed from the stacking direction, the angle between the extension direction of each of the plurality of beams and the axial direction of the imaginary axis when viewed from the stacking direction is either 40 degrees or more and less than 50 degrees or 130 degrees or more and less than 140 degrees.

58. The piezoelectric device according to any one of claims 50 to 54, wherein, The piezoelectric layer is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

59. The piezoelectric device according to any one of claims 50 to 54, wherein, The minimum width of each of the first connecting portion and the second connecting portion is larger than the thickness of each of the plurality of layers in the stacking direction.

60. A piezoelectric device, wherein, The piezoelectric device includes: Base; Multiple beam portions, each having a fixed end connected to the base and a top end located on the side opposite to the fixed end, extending from the fixed end toward the top end; and A connecting portion that connects a pair of adjacent beams among the plurality of beam portions. The multiple beams are piezoelectric vibrating parts comprising multiple layers. A first slit is provided between the pair of beams by a portion of a pair of adjacent end edges of the pair of beams, and a second slit is provided at a different location by another portion of a pair of adjacent end edges of the pair of beams. The connecting portion is located at least between the first slit and the second slit. The connecting portion has: a first end portion connected to one of the pair of beam portions; a second end portion connected to the other of the pair of beam portions, and opposite to the first end portion in the direction in which the pair of beam portions are arranged; a bridging portion folded back between the pair of beam portions and provided for connecting the pair of beam portions to each other; a first connecting portion connected to the portion of the bridging portion located on one side of the pair of beam portions; and a second connecting portion connected to the portion of the bridging portion located on the other side of the pair of beam portions, and located along the position of the first connecting portion. The connecting portion has only one first end and only one second end. The first end and the second end are respectively located at a distance from the top end of the pair of beams that is closer than the distance from the fixed end. The minimum width of each of the first connecting portion and the second connecting portion is larger than the thickness of each of the plurality of layers in the stacking direction.

61. The piezoelectric device according to claim 60, wherein, The first slit is located on the fixed end side of each of the pair of beams relative to the bridging portion. The second slit is located on the top end side of each of the pair of beams relative to the bridging portion.

62. The piezoelectric device according to claim 60, wherein, The piezoelectric device includes two beams that serve as the plurality of beams. The two beam sections are located at their respective top ends facing each other. The first slit and the second slit are respectively located between the top ends of the two beams.

63. The piezoelectric device according to claim 62, wherein, The two beams extend in the same direction as each other. The first slit and the second slit extend in directions orthogonal to the respective extension directions of the two beams.

64. The piezoelectric device according to claim 63, wherein, The fixed end and the top end are respectively located in a direction orthogonal to the respective extension directions of the two beams.

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