transducer

Abstract

A transducer (100) includes a base (110), a plurality of beam portions (120), and a bonding material portion (130). The plurality of beam portions (120) respectively include a piezoelectric layer (10), a first electrode layer (20), and a second electrode layer (30). The bonding material portion (130) connects the plurality of beam portions (120) to each other in a gap (123) formed between adjacent beam portions (120). The bonding material portion (130) is provided continuously from an upper portion of the base (110) to the gap (123). The bonding material portion (130) is made of a material having a Young's modulus lower than that of a material constituting the piezoelectric layer (10). In an axial direction of a central axis of the base (110), a maximum thickness of the bonding material portion (130) at an upper portion of the base (110) is thicker than a thickness of each of the plurality of beam portions (120).

Description

Technical Field

[0001] This invention relates to transducers, and in particular, to sound transducers capable of being used as transmitters of sound waves and receivers of sound waves (microphones). Specifically, it relates to an ultrasonic transceiver capable of transmitting and receiving ultrasonic waves. Background Technology

[0002] Japanese Patent Application Publication No. 61-150499 (Patent Document 1) discloses the structure of a transducer. The transducer described in Patent Document 1 is a segmented piezoelectric vibrating plate. The segmented piezoelectric vibrating plate includes a piezoelectric vibrating plate. An electrode surface is covered on the surface of the piezoelectric vibrating plate. The piezoelectric vibrating plate includes a thin piezoelectric ceramic plate and a thin metal plate. The piezoelectric ceramic plate is attached to one or both sides of the thin metal plate. A retaining portion is provided on the outer periphery of the piezoelectric vibrating plate. Multiple radial slits are provided on the piezoelectric ceramic plate in the portion other than the retaining portion. Each slit is filled with an insulating viscoelastic resin.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 61-150499 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the transducer described in Patent Document 1, the insulating viscoelastic resin located in the slit groove is sometimes peeled off due to the vibration of the vibrating plate. As a result, the device characteristics of the transducer are reduced.

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide a transducer that improves device characteristics by stably holding the bonding material portion located in the slit formed between a plurality of adjacent beams.

[0009] Solution for solving the problem

[0010] The transducer based on the present invention includes a base, a plurality of beam portions, and a bonding material portion. The base is annular. The plurality of beam portions each have a fixed end and a top end. The fixed end is connected to the inner periphery of the base. The top end is located on the side opposite to the fixed end. The plurality of beam portions extend from the fixed end toward the top end away from the inner periphery. The plurality of beam portions each include a piezoelectric layer, a first electrode layer, and a second electrode layer. The first electrode layer is disposed on one side of the piezoelectric layer along the axial direction of the central axis of the base. The second electrode layer is disposed at least partially opposite to the first electrode layer, separated by the piezoelectric layer. The bonding material portion connects the plurality of beam portions to each other in a slit formed between adjacent beam portions. The bonding material portion is provided continuously from the upper part of the base into the slit. The bonding material portion is made of a material with a Young's modulus lower than that of the material constituting the piezoelectric layer. Along the axial direction of the central axis of the base, the maximum thickness of the bonding material portion located at the upper part of the base is thicker than the thickness of each of the plurality of beam portions.

[0011] The effects of the invention

[0012] Therefore, the bonding material portion located in the slit formed between multiple adjacent beams can be stably maintained, thus improving the device characteristics. Attached Figure Description

[0013] Figure 1 This is a top view of the transducer according to Embodiment 1 of the present invention.

[0014] Figure 2 Observe from the direction of the arrow on line II-II Figure 1 The cross-sectional view obtained from the transducer.

[0015] Figure 3 Observe from the direction of the arrow on line III-III Figure 1 The cross-sectional view obtained from the transducer.

[0016] Figure 4 Observe from the direction of the arrow on line IV-IV Figure 1 The cross-sectional view obtained from the transducer.

[0017] Figure 5 Observe from the direction of the arrow on line V-V Figure 1 The cross-sectional view obtained from the transducer.

[0018] Figure 6 This is a top view of the transducer of the first modified embodiment 1 of the present invention.

[0019] Figure 7 This is a cross-sectional view of the transducer in the second modified example of Embodiment 1 of the present invention.

[0020] Figure 8This is a top view showing the transducer of the third modified example of Embodiment 1 of the present invention.

[0021] Figure 9 Observe from the direction of the arrow on line IX-IX Figure 8 The cross-sectional view obtained from the transducer.

[0022] Figure 10 This is a partial cross-sectional view schematically showing the beam portion of the transducer according to Embodiment 1 of the present invention.

[0023] Figure 11 This is a partial cross-sectional view schematically showing the beam portion of the transducer in Embodiment 1 of the present invention during operation.

[0024] Figure 12 This is a perspective view that simulates the state of the transducer of Embodiment 1 of the present invention vibrating in a basic vibration mode.

[0025] 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 transducer according to Embodiment 1 of the present invention.

[0026] Figure 14 This is a cross-sectional view showing the state in which the first support portion is provided in the manufacturing method of the transducer according to Embodiment 1 of the present invention.

[0027] 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 transducer according to Embodiment 1 of the present invention.

[0028] 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 transducer according to Embodiment 1 of the present invention.

[0029] Figure 17 This is a cross-sectional view showing the state in which the first electrode layer is provided in the piezoelectric layer during the manufacturing method of the transducer according to Embodiment 1 of the present invention.

[0030] Figure 18 This is a cross-sectional view showing the state in which a slit is formed from the side of the piezoelectric layer opposite to the support layer side to the upper surface of the substrate layer in the manufacturing method of the transducer according to Embodiment 1 of the present invention.

[0031] Figure 19 This is a cross-sectional view showing the state in which a through hole is formed from the side of the piezoelectric layer opposite to the support layer side to the upper surface of the second electrode layer in the manufacturing method of the transducer according to Embodiment 1 of the present invention.

[0032] Figure 20This is a cross-sectional view showing the state in which the opening is formed during the manufacturing method of the transducer according to Embodiment 1 of the present invention.

[0033] Figure 21 This is a cross-sectional view showing the state before the bonding material section is installed in the manufacturing method of the transducer according to Embodiment 1 of the present invention.

[0034] Figure 22 This is a cross-sectional view showing the state at a certain moment after the liquid bonding material portion is applied in the transducer manufacturing method of Embodiment 1 of the present invention.

[0035] Figure 23 This is a cross-sectional view of the transducer of the fourth variation of Embodiment 1 of the present invention.

[0036] Figure 24 This is a top view showing the transducer according to Embodiment 2 of the present invention. Detailed Implementation

[0037] Hereinafter, transducers 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.

[0038] (Implementation Method 1)

[0039] Figure 1 This is a top view of the transducer 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 transducer. Figure 3 Observe from the direction of the arrow on line III-III Figure 1 The cross-sectional view obtained from the transducer. Figure 4 Observe from the direction of the arrow on line IV-IV Figure 1 The cross-sectional view obtained from the transducer. Figure 5 Observe from the direction of the arrow on line V-V Figure 1 The cross-sectional view obtained from the transducer.

[0040] like Figures 1-5 As shown, the transducer 100 of Embodiment 1 of the present invention includes a base 110, a plurality of beam portions 120, and a bonding material portion 130. In the transducer 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.

[0041] like Figures 1-5As shown, the base 110 is annular. A plurality of recesses 112 are formed on the upper part of the base 110. Details regarding the components constituting the base 110 and the plurality of recesses 112 will be described later. Furthermore, the upper part of the base 110 is the portion of the base 110 facing one side axially along the central axis of the annular base 110, and is not limited to the portion of the base 110 located at the outermost position along the aforementioned axial direction. Additionally, the upper part of the base 110 is not limited to the upper part of any specific component constituting the base 110.

[0042] like Figure 3 As shown, in this embodiment, along the axial direction of the central axis of the annular base 110, the base 110 includes an upper base 110A located on one side and a lower base 110B located on the other side. The inner periphery 111 of the base 110, except for... Figure 1 and Figure 2 The portion showing the recess 112 is formed such that the inner periphery 111A of the upper base 110A and the inner periphery 111B of the lower base 110B are continuously connected. More specifically, in this embodiment, when viewed from the axial direction, the inner periphery 111A of the upper base 110A and the inner periphery 111B of the lower base 110B, except for the portion where the recess 112 is formed, are located in an overlapping position. Alternatively, when viewed from the axial direction, at least a portion of the inner periphery 111B of the lower base 110B may be located on the inner periphery side (the central axis side) of the upper base 110A. For example, the portion of the inner periphery 111B of the lower base 110B located on the side of the upper base 110A may, when viewed from the axial direction, be located at a position overlapping with the inner periphery 111A of the upper base 110A, except for the portion where the recess 112 is formed. Furthermore, the portion of the inner periphery 111B of the lower base 110B located on the side opposite to the upper base 110A may, when viewed from the axial direction, be located on the inner periphery side (the central axis side) of the upper base 110A.

[0043] like Figure 1 and Figure 3As shown, each of the multiple beam portions 120 has a fixed end portion 121 and a top end portion 122. The fixed end portion 121 is connected to the inner periphery 111 of the base portion 110. Specifically, the fixed end portion 121 is connected only to the inner periphery 111A of the upper base portion 110A, and not to the inner periphery of the lower base portion 110B. In this embodiment, the fixed end portion 121 is located in the same plane along a direction orthogonal to the central axis of the base portion 110. The top end portion 122 is located on the side opposite to the fixed end portion 121. The multiple beam portions 120 extend from the fixed end portion 121 toward the top end portion 122 away from the inner periphery 111. In this embodiment, the multiple beam portions 120 extend along the aforementioned plane when the transducer 100 is not driven.

[0044] like Figure 1 As shown, in this embodiment, each of the plurality of beam portions 120 has a tapered shape in its extending direction when viewed axially from the central axis. Specifically, each of the plurality of beam portions 120 has a triangular shape when viewed axially from the central axis. In this embodiment, the triangular shape is an isosceles triangle with the fixed end 121 as its base and the vertex located at the apex 122. That is, the extending direction of each of the plurality of beam portions 120 is the direction connecting the midpoint of the base of the isosceles triangle that forms the shape of each beam portion 120 and the vertex. In this embodiment, from the viewpoint of facilitating bending vibration, it is preferable that the length of each of the plurality of beam portions 120 in its extending direction is at least 5 times the axial thickness of each of the plurality of beam portions 120 along the central axis.

[0045] like Figure 1 As shown, the transducer 100 of this embodiment includes four beam portions 120. Furthermore, when viewed axially from the central axis of the base 110, the top ends 122 of each of the beam portions 120 are positioned towards the central axis. More specifically, the beam portions 120 are arranged in a manner that is point-symmetrical about an imaginary center point of the transducer 100 when viewed axially from the central axis. In this embodiment, the four beam portions 120 are arranged such that, when viewed axially from the central axis, they extend in different directions in a plane orthogonal to the central axis, and the extension directions of adjacent beam portions 120 differ from each other by 90°.

[0046] A slit 123 is formed between adjacent beam portions 120. In this embodiment, the slit 123 is formed as a slit 123. The slits 123 are interconnected on the top end portion 122 side of the beam portions 120.

[0047] Preferably, the width of the slit 123 is as narrow as possible. The slit width of the slit 123 is preferably 10 μm or less, and more preferably 1 μm or less.

[0048] like Figures 1-5 As shown, the multiple beams 120 each include a piezoelectric layer 10, a first electrode layer 20, and a second electrode layer 30.

[0049] The piezoelectric layer 10 is made of a single crystal. The cutting orientation of the piezoelectric layer 10 is appropriately selected to exhibit desired device characteristics. In this embodiment, the piezoelectric layer 10 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 10 is, for example, 0.3 μm or more and 5.0 μm or less.

[0050] The material constituting the piezoelectric layer 10 is appropriately selected to enable the transducer 100 to exhibit the desired device characteristics. In this embodiment, the piezoelectric layer 10 is composed of an inorganic material. Specifically, the piezoelectric layer 10 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 10 is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

[0051] like Figure 3 As shown, the first electrode layer 20 is disposed on one side of the piezoelectric layer 10 along the axial direction of the central axis of the base 110. The second electrode layer 30 is disposed on the other side of the piezoelectric layer 10 along the aforementioned axial direction. The second electrode layer 30 is disposed in each of the plurality of beam portions 120 in such a manner that it is at least partially opposite to the first electrode layer 20 in the aforementioned axial direction, separated by the piezoelectric layer 10. In addition, in this embodiment, an adhesive layer (not shown) is disposed between the first electrode layer 20 and the piezoelectric layer 10 and between the second electrode layer 30 and the piezoelectric layer 10.

[0052] In this embodiment, the first electrode layer 20 and the second electrode layer 30 are each made of Pt. The first electrode layer 20 and the second electrode layer 30 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 20, the second electrode layer 30, and the sealing layer may each be an epitaxially grown film. When the piezoelectric layer 10 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 20 or the second electrode layer 30, it is preferable that the sealing layer is made of NiCr. This improves the reliability of the transducer 100.

[0053] In this embodiment, the thickness of each of the first electrode layer 20 and the second electrode layer 30 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.

[0054] Each of the multiple beam portions 120 further includes a support layer 40. The support layer 40 is disposed on the side of the piezoelectric layer 10 opposite to the side of the first electrode layer 20 and on the side of the second electrode layer 30 opposite to the side of the piezoelectric layer 10. The support layer 40 has a first support portion 41 and a second support portion 42 stacked on the side of the first support portion 41 opposite to the side of the piezoelectric layer 10. In this embodiment, the first support portion 41 is made of SiO2, and the second support portion 42 is made of single-crystal Si. In this embodiment, from the viewpoint of bending vibration of the multiple beam portions 120, it is preferable that the thickness of the support layer 40 is thicker than the thickness of the piezoelectric layer 10. Furthermore, the mechanism of bending vibration of the multiple beam portions 120 will be described later.

[0055] Furthermore, the components constituting the base 110 will be explained. For example... Figure 4 As shown, the base 110 and the plurality of beam portions 120 similarly include a piezoelectric layer 10, a first electrode layer 20, a second electrode layer 30, and a support layer 40. Furthermore, the base 110 also includes a substrate layer 50, a first connecting electrode layer 60, and a second connecting electrode layer 70. Specifically, in this embodiment, the upper base 110A includes a piezoelectric layer 10, a first electrode layer 20, a second electrode layer 30, a support layer 40, a first connecting electrode layer 60, and a second connecting electrode layer 70, while the lower base 110B includes a substrate layer 50.

[0056] The substrate layer 50 is connected axially along the central axis to the side of the support layer 40 opposite to the piezoelectric layer 10 side. The substrate layer 50 includes a first substrate layer 51 and a second substrate layer 52 stacked axially along the central axis on the side of the first substrate layer 51 opposite to the support layer 40 side. That is, in this embodiment, the portion of the lower base 110B located on the side of the upper base 110A is formed by the first substrate layer 51, and the portion of the lower base 110B located on the side opposite to the upper base 110A side is formed by the second substrate layer 52. In this embodiment, the first substrate layer 51 is made of SiO2, and the second substrate layer 52 is made of single-crystal Si.

[0057] like Figure 4 As shown, the first connecting electrode layer 60 is electrically connected to the first electrode layer 20 via a sealing layer (not shown) and exposed to the outside. Specifically, the first connecting electrode layer 60 is disposed on the side of the first electrode layer 20 of the base 110 opposite to the piezoelectric layer 10 side.

[0058] The second connecting electrode layer 70 is electrically connected to the second electrode layer 30 via a sealing layer (not shown) and exposed to the outside. Specifically, the second connecting electrode layer 70 is disposed on the side of the second electrode layer 30 of the base 110 opposite to the side of the support layer 40.

[0059] The thickness of each of the first connecting electrode layer 60 and the second connecting electrode layer 70 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 60 and the sealing layer connected to the second connecting electrode layer 70 is, for example, 0.005 μm or more and 0.1 μm or less.

[0060] In this embodiment, the first connecting electrode layer 60 and the second connecting electrode layer 70 are both made of Au. The first connecting electrode layer 60 and the second connecting electrode layer 70 may also be made of other conductive materials such as Al. The sealing layer connected to the first connecting electrode layer 60 and the sealing layer connected to the second connecting electrode layer 70 are, for example, made of Ti. These sealing layers may also be made of NiCr.

[0061] In this embodiment, the piezoelectric layer 10, the first electrode layer 20, the second electrode layer 30, and the support layer 40 constituting the base 110 are configured to be continuous with the piezoelectric layer 10, the first electrode layer 20, the second electrode layer 30, and the support layer 40 constituting the plurality of beam portions 120 in a direction along an imaginary plane orthogonal to the central axis of the base 110. More specifically, the piezoelectric layer 10, the first electrode layer 20, the second electrode layer 30, and the support layer 40 constituting the upper base 110A are configured to be continuous with the piezoelectric layer 10, the first electrode layer 20, the second electrode layer 30, and the support layer 40 constituting the plurality of beam portions 120 in the aforementioned direction.

[0062] In the transducer 100 of this embodiment, an opening 101 is formed that opens axially along the central axis to the side opposite to the piezoelectric layer 10. The opening 101 is a space surrounded by a base 110, a plurality of beams 120, and a slit 123. Specifically, in this embodiment, the opening 101 is a space surrounded by a lower base 110B, a plurality of beams 120, and a slit 123. That is, in this embodiment, as... Figure 3 As shown, the upper base 110A is divided from the lower base 110B by forming an opening 101. Furthermore, as... Figure 1 and Figure 3 As shown, by forming a slit 123, a plurality of beam portions 120 are divided from the upper base 110A, and a fixed end portion 121 is formed. As a result, the portion with the fixed end portion 121 becomes the inner periphery 111A of the upper base 110A.

[0063] Here, details of the plurality of recesses 112 formed on the upper part of the base 110 are described. For example... Figures 1-3 as well as Figure 5 As shown, multiple recesses 112 are continuous with slits 123. When viewed axially from the central axis of the base 110, the maximum width of the recess 112, which is orthogonal to the extending direction of the slit 123, is larger than the width of the slit 123. When viewed axially as described above, the maximum width of the recess 112 is, for example, 50 μm or more and 200 μm or less.

[0064] More specifically, in this embodiment, each of the plurality of recesses 112 has an inner recess 112A located on the side of the slit 123 and an outer recess 112B located on the side opposite to the slit side and connected to the inner recess 112A. When viewed axially from the central axis, the width of the inner recess 112A, orthogonal to the extension direction of the slit 123, is approximately the same as the width of the slit 123. When viewed axially from the central axis, the maximum width of the outer recess 112B, orthogonal to the extension direction of the slit 123, is larger than the width of the slit 123.

[0065] When viewed axially from the aforementioned central axis, the outer recess 112B has a generally circular shape. The inner diameter of the outer recess 112B when viewed axially is, for example, 50 μm or more and 200 μm or less.

[0066] In addition, such as Figure 5 As shown, in this embodiment, a recess 112 is formed by forming a notch in a portion of the piezoelectric layer 10 and the support layer 40 from the inner periphery 111 of the base 110 toward the outer periphery of the base 110. That is, in this embodiment, the recess 112 is formed on the piezoelectric layer 10 side of the base 110, and the bottom surface 112a of the recess 112 is the surface on the support layer 40 side of the substrate layer 50.

[0067] Furthermore, the recess 112 can also be formed by forming a notch from the inner periphery 111 of the base 110 toward the outer periphery of the base 110 on a portion of the piezoelectric layer 10, the first support portion 41, and the side of the first support portion 41 of the second support portion 42. In this case, the bottom surface 112a of the recess 112 can also be the surface of the stepped portion of the second support portion 42 formed by forming a notch as described above. Alternatively, the recess 112 can also be formed by forming a notch from the inner periphery 111 of the base 110 toward the outer periphery of the base 110 on the piezoelectric layer 10 and the first support portion 41. In this case, the bottom surface 112a of the recess 112 is the surface of the second support portion 42 on the side of the first support portion 41. Moreover, the recess 112 can also be formed by forming a notch from the inner periphery 111 of the base 110 toward the outer periphery of the base 110 on a portion of the piezoelectric layer 10 and the side of the piezoelectric layer 10 of the first support portion 41. In this case, the bottom surface 112a of the recess 112 can also be the surface of the stepped portion of the first support portion 41 formed by forming a notch as described above.

[0068] The recess 112 can also be formed by forming a notch in the piezoelectric layer 10, the support layer 40, and the support layer 40 side of the substrate layer 50 from the inner periphery 111 of the base 110 toward the outer periphery of the base 110. In this case, the bottom surface 112a of the recess 112 can also be the surface of the stepped portion of the substrate layer 50 formed by forming a notch as described above.

[0069] like Figure 1 and Figure 3 As shown, the material section 130 connects the multiple beam sections 120 to each other in a slit 123 formed between adjacent multiple beam sections 120 in such a way that each of the multiple beam sections 120 can be displaced axially along the central axis from the fixed end 121.

[0070] Therefore, as described above, it is preferable to form the slits 123 between the plurality of beam portions 120 as narrow as possible. This prevents the bonding material portions 130 from partially detaching towards the opening 101 when they are formed within the slits 123. Furthermore, the bonding material portions 130 can be easily used to connect the plurality of beam portions 120 to each other.

[0071] Alternatively, the bonding material portion 130 located within the slit 123 may be positioned continuously within the slit 123, overlapping with each of the adjacent beam portions 120 when viewed axially from the central axis. However, from the viewpoint of reducing the weight difference among the beam portions 120, it is preferable that the area of ​​the bonding material portion 130 overlapping with each beam portion 120 is as small as possible when viewed axially from the central axis. For example, it is preferable that the bonding material portion 130 does not contact the first electrode layer 20 of each of the beam portions 120 when viewed axially from the central axis.

[0072] like Figure 1 As shown, in this embodiment, there is a portion within the slit 123 where, when viewed axially from the central axis, there is no bonding material portion 130. Specifically, in this embodiment, there is no bonding material portion 130 in the central gap portion 124 where the plurality of slits 123 are interconnected. Therefore, in this embodiment, the top ends 122 of each of the plurality of beam portions 120 are not connected to each other by bonding material portions 130 but are separated from each other. Figure 5 As shown, the central gap 124 is connected to the opening 101.

[0073] Furthermore, in this embodiment, it is preferable that the minimum width dimension of the central gap portion 124 is larger than the slit width dimension of the slit 123 when viewed axially from the aforementioned central axis. Therefore, in the central gap portion 124, it is possible to easily form portions of multiple beam portions 120 that are separated from each other by the connecting material portions 130.

[0074] Furthermore, in this embodiment, the central gap 124 can be further increased by forming notches at the top ends 122 of each of the plurality of beams 120. Figure 6 This is a top view of the transducer of the first modified embodiment 1 of the present invention. Figure 6 As shown, in the transducer 100a of the first modification of Embodiment 1 of the present invention, the plurality of beam portions 120 each have a generally trapezoidal shape. In this modification, when viewed axially from the central axis, the minimum width dimension of the central gap portion 124 is, for example, 10 μm or more and 30 μm or less.

[0075] like Figure 3As shown, in this embodiment, when viewed axially from the central axis, the axial thickness of the bonding material portion 130 located within the slit 123 is approximately the same as the axial thickness of each of the plurality of beam portions 120. The axial thickness of the bonding material portion 130 located within the slit 123 can also be larger than the thickness of each of the plurality of beam portions 120. However, from the viewpoint of making the plurality of beam portions 120 easily vibrate, it is preferable that the axial thickness of the bonding material portion 130 located within the slit 123 is as small as possible when viewed axially from the central axis. On the other hand, from the viewpoint of suppressing vibration in the combined vibration mode of the plurality of beam portions 120, it is preferable that the axial thickness of the bonding material portion 130 is specifically more than twice the axial depth of the slit 123, that is, more than twice the thickness of each of the plurality of beam portions 120.

[0076] like Figure 1 and Figure 5 As shown, the bonding material portion 130 is provided continuously from the upper part of the base 110 to the slit 123. Specifically, the bonding material portion 130 is provided continuously from the recess 112 to the slit 123. More specifically, the bonding material portion 130 is provided continuously from the outer recess 112B through the inner recess 112A to the slit 123 in a direction along an imaginary plane orthogonal to the aforementioned axis.

[0077] The maximum thickness of the bonding material portion 130 located on the bottom surface 112a of the recess 112 along the axial direction of the central axis of the base 110 is greater than the height of the side wall portion 114 of the recess 112. Furthermore, along the axial direction of the central axis of the base 110, the maximum thickness of the bonding material portion 130 located at the upper part of the base 110 is greater than the thickness of each of the plurality of beam portions 120. The thickest portion of the bonding material portion 130 along the aforementioned central axis is located on the bottom surface 112a of the outer recess 112B. The side of the bonding material portion 130 located on the bottom surface 112a of the outer recess 112B opposite to the bottom surface 112a side is convexly curved.

[0078] The bonding material portion 130 is made of a material whose Young's modulus is lower than that of the material constituting the piezoelectric layer 10. The Young's modulus of the material constituting the bonding material portion 130 is preferably 1 GPa or less. More preferably, the Young's modulus of the material constituting the bonding material portion 130 is 100 MPa or less. The Young's modulus of the material constituting the bonding material portion 130 is preferably 0.1 MPa or more. The Young's modulus of the materials constituting the piezoelectric layer 10 and the bonding material portion 130 can be determined by using physical property values ​​recorded in a known material database for each material. Furthermore, the Young's modulus of the materials constituting the piezoelectric layer 10 and the bonding material portion 130 can also be calculated by measuring the deformation rate when pressure is applied to measurement samples extracted from the piezoelectric layer 10 and the bonding material portion 130 of the transducer 100 using nanoindentation. In this embodiment, it is preferable that the bonding material portion 130 is made of a material with high heat resistance and reflow resistance.

[0079] The bonding material portion 130 is made of an organic material. In embodiments of the present invention, from the viewpoint of Young's modulus, silicone resin or fluoroelastomer are examples of materials constituting the bonding material portion 130. Furthermore, silicone resin has a lower Young's modulus at low temperatures compared to fluoroelastomers. Therefore, it is preferable that the bonding material portion 130 is made of silicone resin. If the bonding material portion 130 is made of silicone resin, the transducer 100 can be used over a wider temperature range. In addition, for example, polyimide resin and parylene (parylene-based polymers) are resins with relatively high and hard Young's moduli, exceeding 1 GPa. Therefore, depending on the Young's modulus of the materials constituting the piezoelectric layer 10, polyimide resin and parylene are sometimes not suitable as materials constituting the bonding material portion 130.

[0080] Furthermore, in this embodiment, the sidewall portion 114 of the recess 112 is located in the axial direction along the central axis, but the sidewall portion 114 of the recess 112 may also be located in the axial direction intersecting the central axis. Figure 7 This is a cross-sectional view showing a transducer of a second modification of Embodiment 1 of the present invention. Figure 7 In, with Figure 5 The same sectional view is illustrated. For example... Figure 7As shown, in the second modification of Embodiment 1 of the present invention, a portion of the sidewall portion 114b of the recess 112 of the transducer 100b is inclined toward the inner periphery 111 of the base 110 as it moves from the upper part of the base 110 toward the bottom surface 112a. In this modification, the maximum thickness of the bonding material portion 130 located at the upper part of the base 110 is also greater than the thickness of each of the plurality of beam portions 120 in the axial direction of the central axis of the base 110. Furthermore, in this modification, the bonding material portion 130 is provided continuously from the recess 112 to the slit 123.

[0081] In addition, in this embodiment, if the maximum thickness of the bonding material portion 130 located at the upper part of the base 110 is greater than the thickness of each of the plurality of beam portions 120, the recess 112 may not be provided in the base 110. Figure 8 This is a top view showing the transducer of the third modified example of Embodiment 1 of the present invention. Figure 9 Observe from the direction of the arrow on line IX-IX Figure 8 A cross-sectional view obtained from the transducer. For example... Figure 8 and Figure 9 As shown, the transducer 100c of the third variation of Embodiment 1 of the present invention may not have a recess formed by forming a notch from the inner periphery 111 side of the base 110 toward the outer periphery side. Instead, a plurality of wall portions 114c are provided on the piezoelectric layer 10 side of the base 110 in the axial direction of the central axis.

[0082] Multiple wall portions 114c are provided such that they extend toward the piezoelectric layer 10 side of the base 110 in the aforementioned axial direction. Furthermore, each of the multiple wall portions 114c is located in contact with the bonding material portion 130 on the base 110 when viewed from the aforementioned axial direction. Each of the multiple wall portions 114c is not located in the portion facing the slit 123 when viewed from the aforementioned axial direction. In this modified example, the bonding material portion 130 is also provided continuously from the upper part of the base 110 into the slit 123.

[0083] The transducer 100 of this embodiment is configured such that multiple beams 120 are each capable of bending and vibrating. Here, the mechanism of bending and vibrating of the multiple beams 120 will be explained.

[0084] Figure 10 This is a schematic partial cross-sectional view of the beam portion of the transducer according to Embodiment 1 of the present invention. Figure 11 This is a partial cross-sectional view schematically showing a portion of the beam during the operation of the transducer according to Embodiment 1 of the present invention. Furthermore, in Figure 10 and Figure 11 The first and second electrode layers are not shown in the figure.

[0085] like Figure 10 and Figure 11As shown, in this embodiment, among the plurality of beam portions 120, the piezoelectric layer 10 functions as a stretchable layer capable of extending and contracting in an in-plane direction orthogonal to the axial direction of the central axis, while the layers other than the piezoelectric layer 10 function as constraint layers. In this embodiment, the support layer 40 primarily functions as the constraint layer. Thus, the constraint layer and the stretchable layer are stacked in an orthogonal direction 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.

[0086] Furthermore, when the piezoelectric layer 10, which serves as a stretching layer, is to stretch or contract in the aforementioned in-plane direction, the support layer 40, which is the main part of the constraint layer, constrains the stretching or contraction of the piezoelectric layer 10 at the interface with the piezoelectric layer 10. Additionally, in this embodiment, in each of the plurality of beam portions 120, the piezoelectric layer 10, 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 40, 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 10, which serves as the expansion and contraction layer, expands and contracts in the aforementioned in-plane direction, the plurality of beam portions 120 bend in an orthogonal direction orthogonal to the aforementioned in-plane direction. Furthermore, the longer the separation distance between the stress-neutral surface N and the piezoelectric layer 10, 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 10 that is about to expand and contract, the greater the displacement. Thus, the plurality of beam portions 120 bend and vibrate in an orthogonal direction orthogonal to the aforementioned in-plane direction, starting from the fixed end 121.

[0087] Furthermore, in the transducer 100 of this embodiment, by providing a bonding material portion 130, it is easy to generate vibration in the basic vibration mode and suppress the generation of vibration in the composite vibration mode. Figure 12 This is a perspective view simulating the state of the transducer of Embodiment 1 of the present invention vibrating in a basic vibration mode. Specifically, in Figure 12 The image shows a transducer 100 in which multiple beam sections 120 are displaced toward the first electrode layer 20. Additionally, in... Figure 12 In the middle, the greater the displacement of the multiple beams 120 towards the first electrode layer 20, the lighter the color. Furthermore, in... Figure 12 The first electrode layer 20 is not shown in the figure.

[0088] like Figure 12 As shown, the basic vibration mode refers to the mode in which the phases of the multiple beams 120 bending vibrations are consistent, and the multiple beams 120 as a whole are displaced in either the up or down direction.

[0089] On the other hand, a composite vibration mode refers to a mode in which the phase of at least one of the multiple beams 120 is inconsistent with the phase of the other beams 120 when the multiple beams 120 bend and vibrate separately. In this embodiment, such as Figure 12 As shown, by utilizing the bonding material section 130, multiple beam sections 120 are interconnected within the slit 123, thereby suppressing the generation of composite vibration modes. Furthermore, the bonding material section 130 is made of a material with a lower Young's modulus than the material constituting the piezoelectric layer 10, allowing for easy deformation while simultaneously suppressing composite vibrations by interconnecting the multiple beam sections 120. Therefore, the bending vibrations of the multiple beam sections 120 under their fundamental vibration modes, which are hindered by the bonding material section 130, can be suppressed, resulting in the fundamental vibration mode dominating over the composite vibration mode in the transducer 100.

[0090] Furthermore, in this embodiment, the maximum thickness of the bonding material portion 130 located at the upper part of the base 110 is relatively thick. Therefore, the bonding material portion 130 and the base 110 are firmly connected by the frictional force between the bonding material portion 130 and the base 110. Thus, even if the multiple beam portions 120 vibrate individually, the bonding material portion 130 within the slit 123 is stably held in place by the base 110. Additionally, in this embodiment, the bonding material portion 130 is arranged continuously from the recess 112 to the slit 123. Therefore, the bonding material portion 130 and the base 110 are firmly connected by the frictional force between the bonding material portion 130 within the recess 112 and the inner surface of the recess 112. Thus, even if the multiple beam portions 120 vibrate individually, the bonding material portion 130 within the slit 123 is stably held in place by the base 110.

[0091] Furthermore, the transducer 100 of this embodiment readily generates vibrations in the basic vibration mode and suppresses the generation of composite vibration modes, thus improving the device characteristics, especially when used as an ultrasonic transducer. The following describes the function of the transducer 100 when used as an ultrasonic transducer.

[0092] First, such as Figure 1 As shown, when ultrasonic waves are generated using the transducer 100, a voltage is applied between the first connecting electrode layer 60 and the second connecting electrode layer 70. Furthermore, as... Figure 4 As shown, a voltage is applied between the first electrode layer 20, which is connected to the first connecting electrode layer 60, and the second electrode layer 30, which is connected to the second connecting electrode layer 70. Furthermore, as... Figure 3As shown, in each of the plurality of beam sections 120, a voltage is applied between the first electrode layer 20 and the second electrode layer 30, which are opposite to each other and separated by the piezoelectric layer 10. This causes the piezoelectric layer 10 to expand and contract in a plane orthogonal to the central axis, and thus, according to the mechanism described above, the plurality of beam sections 120 respectively bend and vibrate axially along the central axis. Therefore, by applying force to the medium surrounding the plurality of beam sections 120 of the transducer 100, the medium vibrates, thereby generating ultrasonic waves.

[0093] Furthermore, in the transducer 100 of this embodiment, each of the plurality of beam portions 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 beam portions 120 when bending increases.

[0094] When detecting ultrasound using transducer 100, the medium surrounding each of the plurality of beams 120 vibrates due to the ultrasound, 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 10. This stress induces charges in the piezoelectric layer 10. Using the charges induced in the piezoelectric layer 10, a potential difference is generated between the first electrode layer 20 and the second electrode layer 30, which are separated by the piezoelectric layer 10. This potential difference is detected in the first connecting electrode layer 60 connected to the first electrode layer 20 and the second connecting electrode layer 70 connected to the second electrode layer 30. Therefore, ultrasound can be detected in transducer 100.

[0095] 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.

[0096] Thus, when the transducer 100 of this embodiment is used as an ultrasonic transducer, the design of the resonant frequencies of the plurality of beam portions 120 becomes important. These resonant frequencies vary depending on the length of each beam portion 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 beam portions 120. Furthermore, it is preferable that the plurality of beam portions each have the same resonant frequency. For example, when the thicknesses of the plurality of beam portions 120 are different, by adjusting the length of each beam portion 120 in its extending direction, the plurality of beam portions 120 can each have the same resonant frequency.

[0097] For example, in Figures 1-5In the transducer 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 constituent material of the piezoelectric layer 10 is set to lithium niobate, the thickness of the piezoelectric layer 10 is set to 1μm, the thickness of the first electrode layer 20 and the second electrode layer 30 is set to 0.1μm, the thickness of the first support portion 41 is set to 0.8μm, the thickness of the second support portion 42 is set to 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 set to 400μm, and the length of the fixed end 121 when viewed axially from the central axis is set to 800μm.

[0098] Furthermore, in the transducer 100 of this embodiment, by providing a bonding material portion 130 stably held by the base 110 within the slit 123, vibrations in the basic vibration mode are easily generated, as described above, suppressing the generation of composite vibration modes. Therefore, when the transducer 100 is used as an ultrasonic transducer, even when detecting ultrasonic waves with the same frequency component as the resonant frequency, it is possible to suppress the situation where the phases of the vibrations of the multiple beam portions 120 are different. Furthermore, it is possible to suppress the situation where the charges generated in the piezoelectric layer 10 of each of the multiple beam portions 120 cancel each other out in the first electrode layer 20 or the second electrode layer 30 due to the phase differences of the vibrations of the multiple beam portions 120.

[0099] In this way, the device characteristics of the transducer 100 as an ultrasonic transducer are improved.

[0100] The following describes a method for manufacturing the transducer 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 during the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 13 and the following Figures 14-18 as well as Figure 20 In, with Figure 3 The same sectional view is illustrated.

[0101] like Figure 13 As shown, firstly, an adhesive layer (not shown) is formed on the lower surface of the piezoelectric single-crystal substrate 10a, and then a second electrode layer 30 is formed on the side of the adhesive layer opposite to the piezoelectric single-crystal substrate 10a. The second electrode layer 30 is formed into a desired pattern by vapor deposition and lift-off. Alternatively, the second electrode layer 30 can be formed by sputtering over the entire lower surface of the piezoelectric single-crystal substrate 10a and then etching to form the desired pattern. The second electrode layer 30 and the adhesive layer can also be epitaxially grown.

[0102] Figure 14This is a cross-sectional view showing the state in which the first support portion is provided during the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 14 As shown, a first support portion 41 is formed on the lower surface of both the piezoelectric single crystal substrate 10a and the second electrode layer 30 using methods such as CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). Immediately after the first support portion 41 is formed, a portion of the lower surface of the first support portion 41 located on the side opposite to the second electrode layer 30 protrudes. Therefore, the lower surface of the first support portion 41 is planarized by cutting it using methods such as Chemical Mechanical Polishing (CMP).

[0103] 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 transducer according to Embodiment 1 of the present invention. Figure 15 As shown, the laminate 50a, consisting of the second support portion 42 and the substrate layer 50, is bonded to the lower surface of the first support portion 41 by surface activation bonding or atomic diffusion bonding. In this embodiment, the laminate 50a is an SOI (Silicon on Insulator) substrate. Furthermore, by pre-planarizing the upper surface of the second support portion 42 using CMP or the like, the yield of the transducer 100 is improved.

[0104] 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 transducer according to Embodiment 1 of the present invention. Figure 15 and Figure 16 As shown, the upper surface of the piezoelectric single crystal substrate 10a is thinned by grinding with a grinding machine. The thinned upper surface of the piezoelectric single crystal substrate 10a is further polished by CMP or the like, so that the piezoelectric single crystal substrate 10a is formed into a piezoelectric layer 10.

[0105] Alternatively, a release layer can be formed by pre-implanting ions onto the upper surface of the piezoelectric single crystal substrate 10a, and the piezoelectric single crystal substrate 10a can be formed into a piezoelectric layer 10 by peeling off the release layer. Alternatively, the piezoelectric single crystal substrate 10a can be further polished using CMP or the like to form a piezoelectric layer 10.

[0106] Figure 17 This is a cross-sectional view showing the state in which a first electrode layer is provided in the piezoelectric layer during the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 17As shown, an adhesive layer (not shown) is formed on the upper surface of the piezoelectric layer 10, and then a first electrode layer 20 is formed on the side of the adhesive layer opposite to the piezoelectric layer 10. The first electrode layer 20 is formed with a desired pattern by vapor deposition and lift-off. Alternatively, the first electrode layer 20 can be formed by sputtering over the entire upper surface of the piezoelectric layer 10 and then etching to form the desired pattern. The first electrode layer 20 and the adhesive layer can also be epitaxially grown.

[0107] Figure 18 This is a cross-sectional view showing the state in which a slit is formed from the side of the piezoelectric layer opposite to the support layer side to the upper surface of the substrate layer in the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 19 This is a cross-sectional view showing the state in which a through hole is formed from the side of the piezoelectric layer opposite to the support layer side to the upper surface of the second electrode layer in the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 19 In, with Figure 4 The same sectional view is illustrated.

[0108] like Figure 18 As shown, a slit is formed in the piezoelectric layer 10 and the first support portion 41 by dry etching using RIE (Reactive Ion Etching). The slit can also be formed by wet etching using fluorinated nitric acid or the like. Furthermore, the second support portion 42 exposed to the slit is etched using DRIE (Deep Reactive Ion Etching) so that the slit reaches the upper surface of the substrate layer 50. Thus, slit 123 is formed. Additionally, Figure 1 , Figure 2 as well as Figure 5 The recess 112 shown is also formed by removing it using DRIE after performing the aforementioned dry etching or wet etching on a portion of the base 110 simultaneously with the formation of the slit 123. Furthermore, as... Figure 19 As shown, in the portion corresponding to the base 110, the piezoelectric layer 10 is etched using the aforementioned dry etching or wet etching to partially expose the second electrode layer 30.

[0109] And, as Figure 4 As shown, in the portion corresponding to the base 110, adhesive layers (not shown) are respectively provided on the first electrode layer 20 and the second electrode layer 30, and then the first connecting electrode layer 60 and the second connecting electrode layer 70 are formed on the upper surface of each adhesive layer by vapor deposition and stripping. Alternatively, the first connecting electrode layer 60 and the second connecting electrode layer 70 can be formed by sputtering the entire surface of the piezoelectric layer 10, the first electrode layer 20, and the exposed second electrode layer 30, and then forming a desired pattern by etching.

[0110] Figure 20 This is a cross-sectional view showing the state in which the opening is formed during the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 20 As shown, a portion of the second substrate layer 52 in the substrate layer 50 is removed using DRIE, and then a portion of the first substrate layer 51 is removed using RIE. This forms a base 110, a plurality of beam portions 120, and an opening 101.

[0111] Finally, a material bonding section 130 is installed. Figure 21 This is a cross-sectional view showing the state before the bonding material section is installed in the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 22 This is a cross-sectional view showing the state at a certain moment after the liquid bonding material is applied in the manufacturing method of the transducer according to Embodiment 1 of the present invention. Figure 21 and Figure 22 In, with Figure 5 The same sectional view is illustrated.

[0112] like Figure 21 and Figure 22 As shown, for the bonding material portion 130, firstly, a liquid bonding material portion 130 is applied to the bottom surface 112a of each of the plurality of recesses 112 formed on the base 110 in a manner that fills the recesses 112, by means of a dispensing method or a transfer method. In this embodiment, specifically, it is applied to the bottom surface 112a of the outer recesses 112B formed on the base 110 in a manner that fills the outer recesses 112B.

[0113] Thus, as Figure 22 As shown, through capillary action within the narrow slit 123, liquid bonding material portion 130, disposed in a manner filling multiple recesses 112, wets and diffuses from the multiple recesses 112 toward the slit 123, which is connected to the multiple recesses 112, without external force. Specifically, in this embodiment, the liquid bonding material portion 130 is wetted and spreads from the multiple outer recesses 112B of the base 110, via the inner recesses 112A connected to the multiple outer recesses 112B, toward the slit 123 connected to the inner recesses 112A, without external force. Thus, the liquid bonding material portion 130 is disposed within the slit 123. After the liquid bonding material portion 130 is disposed within the slit, it solidifies.

[0114] By using the above-described method to configure the bonding material portion 130, the generation of undesirable liquid accumulation in the bonding material portion 130 disposed within the slit 123 can be suppressed. Furthermore, the weight difference between the multiple beam portions 120 can be reduced, and the symmetry of the vibration of the multiple beam portions 120 can be improved. As a result, the device characteristics of the transducer 100 are improved.

[0115] Based on the above procedures, manufacture as follows: Figures 1-5 The transducer 100 of Embodiment 1 of the present invention is shown as described.

[0116] Furthermore, the material section 130 can also be provided before the opening 101 is formed. For example... Figure 18 As shown, before the opening 101 is formed, the substrate layer 50 is located below the axial direction of the central axis of the slit 123. Therefore, even if the width in the direction orthogonal to the extension direction of the slit 123 when viewed from the axial direction is relatively large, the bonding material portion 130 can be provided in the slit 123 located between the plurality of beam portions 120 without the bonding material portion 130 falling off.

[0117] Figure 23 This is a cross-sectional view of the transducer in the fourth modification of Embodiment 1 of the present invention. Figure 23 In, with Figure 3 The same sectional view is illustrated. For example... Figure 23 As shown, in the fourth modification of Embodiment 1 of the present invention, the slit 123 of the transducer 100d and Figure 3 The slit 123 of the transducer 100 of Embodiment 1 of the present invention shown is relatively large. When the transducer 100d of the fourth variation of Embodiment 1 of the present invention is manufactured in this way, as described above, by providing the bonding material portion 130 before forming the opening portion 101, it is possible to suppress the detachment of the bonding material portion 130.

[0118] As described above, the transducer 100 of Embodiment 1 of the present invention includes a base 110, a plurality of beam portions 120, and a bonding material portion 130. The base 110 is annular. The plurality of beam portions 120 each have a fixed end portion 121 and a top end portion 122. The fixed end portion 121 is connected to the inner periphery 111 of the base 110. The top end portion 122 is located on the side opposite to the fixed end portion 121. The plurality of beam portions 120 each extend away from the inner periphery 111 from the fixed end portion 121 toward the top end portion 122. The plurality of beam portions 120 each include a piezoelectric layer 10, a first electrode layer 20, and a second electrode layer 30. The first electrode layer 20 is disposed on one side of the piezoelectric layer 10 in the axial direction of the central axis of the base 110. The second electrode layer 30 is disposed at least partially opposite to the first electrode layer 20 through the piezoelectric layer 10. A bonding material section 130 connects the multiple beam sections 120 to each other within a slit 123 formed between adjacent beam sections 120. The bonding material section 130 is arranged continuously from the upper part of the base 110 to the slit 123. The bonding material section 130 is made of a material with a lower Young's modulus than the material constituting the piezoelectric layer 10. In the axial direction along the central axis of the base 110, the maximum thickness of the bonding material section 130 located at the upper part of the base 110 is greater than the thickness of each of the multiple beam sections 120.

[0119] Therefore, the bonding material portion 130 located within the slit 123 formed between the multiple adjacent beam portions 120 can be stably held in place by the frictional force acting on the upper part of the base 110, which is continuously disposed therewith, and the upper part of the base 110. This suppresses the possibility of the bonding material portion 130 detaching from the slit 123 due to the vibration of the multiple beam portions 120. Furthermore, the bonding material portion 130 can be used to continuously and stably suppress the generation of at least one of the multiple beam portions 120 in a mode of vibration with a different phase than the other beam portions, i.e., a so-called composite vibration mode, thereby improving the device characteristics of the transducer 100.

[0120] In an embodiment of the present invention, a recess 112 continuous with the slit 123 is formed on the upper part of the base 110. The bonding material portion 130 is provided in a manner that extends continuously from the recess 112 to the slit 123.

[0121] Therefore, the bonding material portion 130 located within the slit 123 formed between the multiple adjacent beam portions 120 can be stably held by the frictional force with the inner surface of the recess 112, thus suppressing the possibility of the bonding material portion 130 falling off from the slit 123 due to vibration of the multiple beam portions 120. This improves the device characteristics of the transducer 100.

[0122] In an embodiment of the present invention, the maximum thickness of the bonding material portion 130 located on the bottom surface 112a of the recess 112 in the axial direction of the central axis of the base 110 is larger than the height of the side wall portion 114 of the recess 112.

[0123] As a result, the friction between the bonding material portion 130 located in the recess 112 and the inner surface of the recess 112 is further increased, which can more stably hold the bonding material portion 130 located in the slit 123, thereby further improving the device characteristics of the transducer 100.

[0124] In an embodiment of the invention, when viewed axially from the central axis of the base 110, the maximum width of the recess 112, which is orthogonal to the extension direction of the slit 123, is larger than the width of the slit 123.

[0125] Therefore, in embodiments of the present invention, the volume of the bonding material portion 130 located on the base 110 can be made sufficiently large compared to the volume of the bonding material portion 130 located within the slit 123. Furthermore, the frictional force between the bonding material portion 130 located within the recess 112 and the inner surface of the recess 112 is further increased, which can further stably hold the bonding material portion 130 located within the slit 123, thereby further improving the device characteristics of the transducer 100.

[0126] In embodiments of the present invention, the Young's modulus of the material constituting the bonding material portion 130 is 1 GPa or less. If the Young's modulus is 1 GPa or less, it is possible to suppress the situation where the multiple beam portions 120 are excessively and firmly connected by the bonding material portion 130, thus facilitating the control of the resonant frequencies of the multiple beam portions 120 for improving device characteristics. Furthermore, when external stresses such as thermal stress are generated in the multiple beam portions 120, the influence of these external stresses on the device characteristics of the transducer 100 can be reduced.

[0127] In an embodiment of the present invention, the piezoelectric layer 10 is made of an inorganic material, while the bonding material portion 130 is made of an organic material. As a result, the Young's modulus of most organic materials is lower than that of inorganic materials, thus facilitating the selection of materials for the piezoelectric layer 10 and the bonding material portion 130, and simplifying the design of the transducer 100.

[0128] In embodiments of the present invention, the material constituting the bonding material portion 130 is a silicone resin or a fluoroelastomer. Therefore, it is easy to design the bonding material portion 130 to be composed of a material with a Young's modulus lower than that of the material constituting the piezoelectric layer 10.

[0129] In embodiments of the present invention, the piezoelectric layer 10 is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3). This improves the piezoelectric properties of the piezoelectric layer 10, thereby enhancing the device characteristics of the transducer 100.

[0130] In an embodiment of the present invention, the slit 123 has a portion in which the bonding material portion 130 is absent. This prevents the pressure difference between the upper and lower sides of each of the multiple beam portions 120 from increasing due to vibration.

[0131] In an embodiment of the present invention, the top ends 122 of each of the plurality of beams 120 are separated from each other instead of being connected by the connecting material 130. Therefore, the plurality of beams 120 can be connected to each other using the connecting material 130, and the top ends 122 can be easily displaced, thereby improving the device characteristics of the transducer 100. Furthermore, ventilation holes can be easily provided using a simple process to suppress the increase in the pressure difference between the upper and lower sides of the plurality of beams 120.

[0132] (Implementation Method 2)

[0133] The transducer according to Embodiment 2 of the present invention will now be described. The main differences between the transducer of Embodiment 2 and the transducer of Embodiment 1 of the present invention are that the integral material portion is disposed within the slit and that through holes are provided in the plurality of beam portions. Therefore, the same structure as the transducer of Embodiment 1 of the present invention will not be described again.

[0134] Figure 24 This is a top view showing the transducer according to Embodiment 2 of the present invention. Figure 24 As shown, in the transducer 200 of Embodiment 2 of the present invention, at least one of the plurality of beam portions 220 has a through hole 225. The through hole 225 extends through at least one of the plurality of beam portions 220 along the central axis of the base 110. The through hole 225 is separated from the slit 123. Therefore, in the transducer 200 of Embodiment 2 of the present invention, by utilizing the through hole 225, it is possible to suppress the situation where the pressure difference between the upper and lower sides of the aforementioned central axis of each of the plurality of beam portions 220 increases when the plurality of beam portions 220 vibrate. Furthermore, it is possible to suppress the deterioration of the device characteristics of the transducer 200.

[0135] Furthermore, in Embodiment 2 of the present invention, each of the plurality of beam portions 220 has a through hole 225 extending axially along the central axis of the base 110. The plurality of through holes 225 are arranged symmetrically with respect to the central axis point. As a result, the plurality of through holes 225 function as ventilation holes, and the symmetry of the plurality of beam portions 220 when viewed axially from the aforementioned central axis is improved. Therefore, the vibration of the plurality of beam portions 220 is easily synchronized, and the device characteristics of the transducer 200 are improved.

[0136] In this embodiment, when viewed axially from the central axis, the bonding material portion 230 located within the slit 123 is disposed as a whole within the plurality of slits 123. That is, in this embodiment, no central gap portion is provided. In this embodiment, even if the bonding material portion 230 is disposed as described above, since the through hole 225 functions as a ventilation hole as described above, the reduction in the device characteristics of the transducer 200 can be suppressed. Furthermore, in this embodiment, it is also possible, similar to the transducer 100 of Embodiment 1 of the present invention, to provide a portion in which the bonding material portion 230 is absent when viewed axially from the central axis.

[0137] Furthermore, in the transducer 200 of Embodiment 2 of the present invention, the maximum thickness of the bonding material portion 230 located at the upper part of the base 110 along the axial direction of the central axis of the base 110 is also greater than the thickness of each of the plurality of beam portions 220. The bonding material portion 230 is provided continuously from the recess 112 to the slit 123. As a result, the bonding material portion 230 is stably maintained, and the device characteristics of the transducer 200 are improved.

[0138] In the above description of the embodiments, the combinable structures can also be combined with each other.

[0139] 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.

[0140] Explanation of reference numerals in the attached figures

[0141] 10. Piezoelectric layer; 10a. Piezoelectric single crystal substrate; 20. First electrode layer; 30. Second electrode layer; 40. Support layer; 41. First support portion; 42. Second support portion; 50. Substrate layer; 50a. Laminate; 51. First substrate layer; 52. Second substrate layer; 60. First connecting electrode layer; 70. Second connecting electrode layer; 100, 100a, 100b, 100c, 100d, 200. Transducer; 101. Opening; 110. Base Part; 110A, upper base; 110B, lower base; 111, 111A, 111B, inner periphery; 112, recess; 112A, inner recess; 112B, outer recess; 112a, bottom surface; 114, 114b, sidewall; 114c, wall; 120, 220, beam; 121, fixed end; 122, top end; 123, slit; 124, central gap; 130, 230, bonding material; 225, through hole.

Claims

1. A transducer, wherein, The transducer includes: A ring-shaped base; A plurality of beam portions having a fixed end connected to the inner periphery of 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 away from the inner periphery; and The material section connects the plurality of beams to each other within a slit formed between adjacent beams, and is arranged continuously from the upper part of the base to the slit. The plurality of beam portions each include: a piezoelectric layer; a first electrode layer disposed on one side of the piezoelectric layer along the axial direction of the central axis of the base; and a second electrode layer disposed in such a manner that it is at least partially opposite the first electrode layer in the axial direction, separated by the piezoelectric layer. The bonding material portion is made of a material with a lower Young's modulus than the material constituting the piezoelectric layer. Along the axial direction of the central axis of the base, the maximum thickness of the bonding material portion located at the upper part of the base is greater than the thickness of each of the plurality of beam portions.

2. The transducer according to claim 1, wherein, A recess that is continuous with the slit is formed in the upper part of the base. The bonding material portion is provided continuously from the recess to the slit.

3. The transducer according to claim 2, wherein, The maximum thickness of the bonding material portion located on the bottom surface of the recess along the axial direction of the central axis of the base is greater than the height of the sidewall portion of the recess.

4. A transducer, wherein, The transducer includes: A ring-shaped base; A plurality of beam portions having a fixed end connected to the inner periphery of 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 away from the inner periphery; and The material section connects the plurality of beams to each other within a slit formed between adjacent beams, and is arranged continuously from the upper part of the base to the slit. The plurality of beams each include: a piezoelectric layer; a first electrode layer disposed on one side of the piezoelectric layer; and a second electrode layer disposed such that it is at least partially opposite to the first electrode layer, separated by the piezoelectric layer. The bonding material portion is made of a material with a lower Young's modulus than the material constituting the piezoelectric layer. A recess that is continuous with the slit is formed in the upper part of the base. The bonding material portion is provided continuously from the recess to the slit.

5. The transducer according to claim 4, wherein, The maximum thickness of the bonding material portion located on the bottom surface of the recess along the axial direction of the central axis of the base is greater than the height of the sidewall portion of the recess.

6. The transducer according to any one of claims 2 to 5, wherein, When viewed axially from the central axis of the base, the maximum width of the recess, which is orthogonal to the extension direction of the slit, is larger than the width of the slit.

7. The transducer according to any one of claims 1 to 5, wherein, The Young's modulus of the material constituting the bonding material portion is less than 1 GPa.

8. The transducer according to any one of claims 1 to 5, wherein, The piezoelectric layer is composed of inorganic materials. The bonding material is composed of organic materials.

9. The transducer according to claim 8, wherein, The material constituting the bonding material portion is silicone resin or fluoroelastomer.

10. The transducer according to claim 8, wherein, The piezoelectric layer is composed of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

11. The transducer according to any one of claims 1 to 5, wherein, The slit contains a portion where the bonding material is absent.

12. The transducer according to claim 11, wherein, The top ends of each of the plurality of beams are not connected to each other by the bonding material but are separate from each other.

13. The transducer according to any one of claims 1 to 5, wherein, At least one of the plurality of beam portions has a through hole that axially extends through at least one of the plurality of beam portions along the central axis of the base. The through hole is separate from the slit.

14. The transducer according to claim 13, wherein, When viewed axially from the central axis of the base, the top ends of each of the plurality of beams are positioned toward the central axis. The plurality of beams each have a through hole extending axially along the central axis. The plurality of through holes are arranged symmetrically with respect to the central axis point.

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