Transducer and manufacturing method of transducer

Abstract

To provide a transducer capable of appropriately securing a clearance between a vibration part including a piezoelectric element and a periphery, and a manufacturing method of a transducer.SOLUTION: A sonic wave generation device 1 which is a transducer comprises: a support substrate 4 including a first cavity 5; a vibration device 6; and a lid body 3 which includes a second cavity 3a and is bonded to the vibration device 6 with an adhesive agent 100. The vibration device 6 includes a first frame part 61 and a cantilever 62 which is a vibration part. A portion of the cantilever 62 is connected to the first frame part 61, the other than the connected portion is separated from the first frame part 61 by a slit 9. The first cavity 5 and the second cavity 3a are communicated by the slit 9. In the first frame part 61, a projection 8 is formed on a bonded plane with the kid body 3, and a first step S1 is formed on an inner surface 615 which faces the slit 9.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] The present disclosure relates to transducers and methods of manufacturing transducers. [Background technology]

[0002] Patent Document 1 describes a transducer including a membrane support part having a cavity, a cantilever-type diaphragm, and a piezoelectric element formed on the diaphragm. In the transducer of Patent Document 1, the membrane support part surrounds the periphery of the diaphragm and is connected to one side of the diaphragm. Gaps are formed between the remaining three sides of the diaphragm and the membrane support part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-52305

[0004] [overview] In the transducer of Patent Document 1, when a driving voltage is applied to the piezoelectric element, the vibration membrane alternately repeats upward and downward displacement. This vibration vibrates the air around the vibration membrane, and the vibration of the air is output as a sound wave. In this case, if the gap between the vibration membrane and the membrane support part surrounding it is not properly secured, the sound characteristics may be affected.

[0005] The present disclosure provides a transducer and a method for manufacturing the transducer that can appropriately ensure a gap between a vibration part having a piezoelectric element and the surrounding area.

[0006] A transducer according to one aspect of the present disclosure includes a support substrate having a first cavity, a vibration device supported by the support substrate, and a lid having a second cavity and bonded to the vibration device with an adhesive, the vibration device having a first frame portion surrounding the first cavity when viewed from the lid portion and having a first bonding surface bonded to the lid body with the adhesive, and a vibration portion facing the first cavity and having a piezoelectric element, a portion of the vibration portion being connected to the first frame portion, and the vibration portion having a first bonding surface bonded to the lid body with the adhesive, the first frame portion being connected to the first frame portion when viewed from a bonding direction of the vibration device and the lid body. A portion of the vibration part other than the connection part between the vibration part and the first frame part is separated from the first frame part by a slit penetrating the vibration device in the joining direction, the lid body has a second frame part that surrounds the second cavity and includes a second bonding surface that is bonded to the first bonding surface by the adhesive, the first cavity and the second cavity are connected by the slit, a convex part is formed on the first bonding surface that is convex toward the second bonding surface, and a first step is formed on the inner surface facing the slit in the first frame part, the first step being recessed from the first bonding surface toward the opposite side to the lid body.

[0007] Another example of a transducer according to one aspect of the present disclosure includes a support substrate having a first cavity, a vibration device supported by the support substrate, and a lid having a second cavity and bonded to the vibration device with an adhesive, the vibration device having a first frame portion surrounding the first cavity when viewed from the lid portion and having a first bonding surface bonded to the lid portion with the adhesive, and a vibration portion facing the first cavity and having a piezoelectric element, a portion of the vibration portion being connected to the first frame portion, and a first bonding surface being bonded to the lid portion with the adhesive, the first bonding surface being bonded to the lid portion with the adhesive, the first bonding surface being bonded to the lid portion with the adhesive, and the vibration portion having a piezoelectric element. In other words, a portion of the vibration part other than the connection portion between the vibration part and the first frame part is separated from the first frame part by a slit that penetrates the vibration device in the joining direction, the lid body has a second frame part that surrounds the second cavity and includes a second bonding surface that is bonded to the first bonding surface by the adhesive, the first cavity and the second cavity are connected by the slit, a convex portion that is convex toward the second bonding surface is formed on the first bonding surface, and a step that is concave toward the opposite side to the vibration device is formed on the inner surface of the second bonding surface that faces the second cavity.

[0008] Yet another example of a transducer according to one aspect of the present disclosure includes a support substrate having a first cavity, a vibration device supported by the support substrate, and a lid having a second cavity and bonded to the vibration device with an adhesive, the vibration device including a first frame portion surrounding the first cavity when viewed from the lid portion and having a first bonding surface bonded to the lid portion with the adhesive, and a vibration portion facing the first cavity and having a piezoelectric element, a portion of the vibration portion being connected to the first frame portion, When viewed from the joining direction of the vibration device and the lid body, a portion of the vibration part other than the connection part between the vibration part and the first frame part is separated from the first frame part by a slit that penetrates the vibration device in the joining direction, the lid body has a second frame part that surrounds the second cavity and includes a second bonding surface that is bonded to the first bonding surface by the adhesive, the first cavity and the second cavity are connected by the slit, a convex portion that is convex toward the second bonding surface is formed on the first bonding surface, and when viewed from the joining direction, the size of the second cavity is larger than the size of the first cavity.

[0009] A method for manufacturing a transducer according to another aspect of the present disclosure is a method for manufacturing a transducer including a support substrate having a first cavity, a vibration device stacked on the support substrate, and a lid having a second cavity and bonded to the vibration device with an adhesive, the method comprising: a laminate manufacturing step of forming a laminate of a first substrate to be the support substrate and the vibration device; a lid manufacturing step of manufacturing the lid; a bonding step of bonding the lid to the vibration device; and a cavity forming step of forming a first cavity in a region in the first substrate where a first cavity is to be formed. The laminate manufacturing step includes a step of forming an intermediate laminate having a vibration film forming layer stacked on the first substrate, a piezoelectric element provided in the vibration film forming layer above the region in which the first cavity is to be formed, and an insulating film covering the piezoelectric element and the vibration film forming layer, a step of forming a groove portion from the insulating film side along the outer periphery of the region in which the first cavity is to be formed in the intermediate laminate, except for a part of the outer periphery of the region in which the first cavity is to be formed, a step of forming a convex portion in the insulating film outside the region in which the first cavity is to be formed, and a step of forming a convex portion on a bottom surface of the groove portion. The method includes a process for obtaining the vibration device by forming a through hole that penetrates a portion of the intermediate laminate, thereby separating the intermediate laminate into a vibration portion including the piezoelectric element and a frame portion that is connected to the vibration portion at a portion and surrounds the vibration portion, and the lid body manufacturing process includes a process for obtaining a lid body by forming a second cavity in a second substrate to be the lid body, the second cavity being connected to the first cavity through the groove portion and the through hole, and the bonding process includes a process for bonding the lid body to the vibration device by applying an adhesive to the bonding surface of the lid body to the vibration device and attaching the lid body to the surface of the vibration device on which the convex portion is formed, thereby bonding the lid body and the vibration device, and the cavity forming process includes a process for forming the first cavity in the first substrate, thereby obtaining a support substrate in which the first cavity is formed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view of a sound wave generating device according to a first embodiment. [Diagram 2] FIG. 2 is a bottom view of the sound wave generating device according to the first embodiment. [Figure 3A] 3A is a cross-sectional view of the sound wave generating device taken along line IIIa-IIIa in FIG. [Figure 3B] 3B is a cross-sectional view of the sound wave generating device taken along line IIIb-IIIb in FIG. 1. FIG. [Figure 4] FIG. 4 is a cross-sectional view of the sound wave generating device taken along line VI-VI in FIG. [Diagram 5] FIG. 5 is an exploded cross-sectional view of the sound wave generating device according to the first embodiment. [Figure 6] FIG. 6 is a plan view of the substrate assembly in the acoustic wave generating device shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is an enlarged view of area A shown in FIG. 3A. [Figure 9] FIG. 9 is a diagram showing the cover of the sound wave generating device shown in FIG. 1 as viewed from the vibration device side. [Figure 10] FIG. 10 is a cross-sectional view showing one step of a manufacturing procedure of a substrate assembly workpiece (laminate) in one example of a manufacturing method for the sound wave generating device according to the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a step carried out following the step shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view showing a step performed following the step shown in FIG. [Figure 13] FIG. 13 is a cross-sectional view showing a step carried out following the step shown in FIG. [Figure 14A] FIG. 14A is a plan view showing a step performed following the step shown in FIG. [Figure 14B] FIG. 14B is a cross-sectional view taken along line XIVb-XIVb in FIG. 14A. [Figure 15A] FIG. 15A is a plan view showing a process carried out following the process shown in FIGS. 14A and 14B. [Figure 15B]FIG. 15B is a cross-sectional view taken along line XVb-XVb in FIG. 15A. [Figure 16] FIG. 16 is a cross-sectional view showing one step of a manufacturing procedure of the lid, in one example of a manufacturing method for the sound wave generating device according to the first embodiment. [Figure 17A] FIG. 17A is a plan view showing a step performed following the step shown in FIG. [Figure 17B] FIG. 17B is a cross-sectional view taken along line XVIIb--XVIIb in FIG. 17A. [Figure 18A] FIG. 18A is a plan view showing a process carried out following the process shown in FIGS. 17A and 17B. [Figure 18B] FIG. 18B is a cross-sectional view taken along line XVIIIb-XVIIIb in FIG. 18A. [Figure 19] FIG. 19 is a cross-sectional view showing a step performed following the step shown in FIGS. 18A and 18B. [Figure 20] FIG. 20 is a cross-sectional view showing a step performed following the step shown in FIG. [Figure 21] FIG. 21 is a cross-sectional view showing a step performed following the step shown in FIG. [Figure 22] FIG. 22 is a cross-sectional view of a lid obtained by carrying out a step subsequent to the step shown in FIG. [Figure 23] FIG. 23 is a diagram showing a step of joining the manufactured substrate assembly work-in-progress (laminate) and the lid body in one example of the method for manufacturing the sound wave generating device according to the first embodiment. [Figure 24] FIG. 24 is a diagram for explaining a reference example of a method for forming a hole in a silicon layer. [Diagram 25] FIG. 25 is a diagram illustrating a method for forming a hole in a silicon substrate when a silicon oxide film exists on a silicon layer. [Figure 26] FIG. 26 is a plan view of a sound wave generating device according to the second embodiment. [Figure 27] FIG. 27 is a cross-sectional view of the sound wave generating device taken along line XXVI-XXVI shown in FIG. [Figure 28] FIG. 28 is a diagram showing the cover of the sound wave generating device shown in FIG. 26 as viewed from the vibration device side. [Figure 29] FIG. 29 is a cross-sectional view showing a step of a manufacturing procedure for the lid of the sound wave generating device according to the second embodiment. [Diagram 30] FIG. 30 is a cross-sectional view showing a step performed following the step shown in FIG. [Diagram 31] FIG. 31 is a cross-sectional view showing a step performed following the step shown in FIG. [Diagram 32] FIG. 32 is a plan view of a sound wave generating device according to the third embodiment. [Diagram 33] 33 is a cross-sectional view of the sound wave generating device taken along line XXXIII-XXXIII in FIG. 32. FIG. [Diagram 34] FIG. 34 is a plan view of a sound wave generating device according to the fourth embodiment. [Diagram 35] 35 is a cross-sectional view of the acoustic wave generating device taken along line XXXV-XXXV in FIG. [Diagram 36] FIG. 36 is a plan view of a sound wave generating device according to the first modification. [Figure 37] FIG. 37 is a cross-sectional view of the sound wave generating device 1 taken along the line XXXVII-XXXVII in FIG. [Figure 38] FIG. 38 is a cross-sectional view of the sound wave generating device 1 taken along the line XXXIII-XXXIII in FIG. [Figure 39] FIG. 39 is a diagram for explaining the second modification.

[0011] [Detailed Description] Hereinafter, the embodiments will be described with reference to the drawings. In the description, the same elements or elements having the same functions are denoted by the same reference numerals, and duplicated description will be omitted.

[0012] (First embodiment) FIG. 1 is a plan view of a sound wave generating device (transducer) according to the first embodiment. FIG. 2 is a bottom view of the sound wave generating device according to the first embodiment. FIG. 3A is a cross-sectional view of the sound wave generating device taken along line IIIa-IIIa in FIG. 1. FIG. 3B is a cross-sectional view of the sound wave generating device taken along line IIIb-IIIb in FIG. 1. FIG. 4 is a cross-sectional view of the sound wave generating device taken along line VI-VI in FIG. 1. FIG. 5 is an exploded cross-sectional view of the sound wave generating device according to the first embodiment. FIG. 5 shows a state in which the cover and the substrate assembly are separated in the sound wave generating device shown in FIG. 3A. FIG. 6 is a plan view of the substrate assembly in the sound wave generating device shown in FIG. 1. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6.

[0013] The sound wave generating device 1 is a device that generates sound waves by vibrating the air through the vibration of a piezoelectric film. The sound wave generating device 1 can also be called a piezoelectric film device because it uses the vibration of the piezoelectric film. The sound wave generating device 1 may be, for example, a speaker, or an ultrasonic generating device that generates ultrasonic waves. In this case, the speaker and the ultrasonic generating device both vibrate the air and can operate with roughly the same structure, but the frequency ranges used are different between the audible range and the ultrasonic range. The sound wave generating device 1 is, for example, a MEMS (Micro Electro Mechanical Systems) device that utilizes piezoelectric properties. Below, an embodiment in which the sound wave generating device 1 is a speaker will be described.

[0014] 1, 2, 3A, 3B, 4 and 5, the sound wave generating device 1 includes a substrate assembly 2 and a cover 3. The cover 3 is bonded to the substrate assembly 2 with an adhesive 100. The substrate assembly 2 includes a support substrate 4 and a vibration device 6 provided on the support substrate 4.

[0015] The support substrate 4 has a quadrangular shape (approximately rectangular) in plan view. In the following description, the longitudinal direction of the approximately rectangular support substrate 4 in plan view is referred to as the X direction, the lateral direction is referred to as the Y direction, and the direction intersecting the X direction and Y direction (i.e., the thickness direction of the support substrate 4) is referred to as the Z direction. The Z direction is also the bonding direction between the vibration device 6 and the lid 3 of the substrate assembly 2. In the Z direction, the direction in which the vibration device 6 is located relative to the support substrate 4 is referred to as "upper", and the direction in which the support substrate 4 is located relative to the piezoelectric element 10 is referred to as "lower".

[0016] The support substrate 4 includes a silicon (Si) substrate 32 and an oxide film 33 formed on the surface of the silicon substrate 32. The support substrate 4 has a thickness of about 380 μm.

[0017] The support substrate 4 has a cavity (first hollow) 5 formed by a through hole penetrating in the Z direction. In a plan view, the cavity 5 has a rectangular parallelepiped shape with a rectangular opening 5a on the lower surface (bottom surface) side of the cavity 5 as the bottom surface.

[0018] The support substrate 4 is frame-shaped in a plan view. The support substrate 4 includes a first portion 41, a second portion 42, a third portion 43, and a fourth portion 44. The first portion 41 and the third portion 43 extend along the Y direction so as to sandwich the cavity 5 therebetween in the X direction. The second portion 42 and the fourth portion 44 extend along the X direction so as to sandwich the cavity 5 therebetween in the Y direction. That is, the first portion 41, the second portion 42, the third portion 43, and the fourth portion 44 surround the cavity 5.

[0019] The inner surface 411 of the first portion 41, the inner surface 421 of the second portion 42, the inner surface 431 of the third portion 43, and the inner surface 441 of the fourth portion 44 are also side surfaces of the cavity 5. Unless otherwise specified, the inner surfaces 411, 421, 431, and 441 are flat surfaces.

[0020] 3A, 3B, 4, 5, and 6, the vibration device 6 has a first frame portion 61 surrounding the cavity 5 when viewed from the lid body 3, and a cantilever (vibration portion) 62 facing the cavity 5 in a plan view. A part of the cantilever 62 is connected to the first frame portion 61. A part of the cantilever 62 other than the connection portion with the first frame portion 61 is separated from the first frame portion 61 by a slit 9 penetrating the vibration device 6 in the Z direction.

[0021] The shape of the first frame 61 in a plan view is the same as that of the support substrate 4. That is, the shape of the first frame 61 in a plan view is generally rectangular in a plan view. The first frame 61 includes a first portion 611, a second portion 612, a third portion 613, and a fourth portion 614.

[0022] The first portion 611 is supported by the first portion 41 of the support substrate 4. The first portion 611 is aligned on the first portion 41 in the Y direction. The second portion 612 is supported by the second portion of the support substrate 4. The second portion 612 is aligned on the second portion in the X direction. The third portion 613 is supported by the third portion 43 of the support substrate 4. The third portion 613 is aligned on the third portion 43 in the Y direction. The fourth portion 614 is supported by the fourth portion 44 of the support substrate 4. The fourth portion 614 is aligned on the fourth portion 44 in the X direction.

[0023] The first frame portion 61 is a portion of the vibration device 6 that is joined to the lid body 3. A surface of the first frame portion 61 is a joining surface (first joining surface) 61a with the lid body 3. As shown in Fig. 6, a plurality of protrusions 8 are discretely arranged on the joining surface 61a so as to surround the cavity 5 in a plan view.

[0024] 6, when viewed from the Z direction, a plurality of protrusions 8 arranged in an annular shape so as to surround the cavity 5 doubly surrounds the cavity 5. Specifically, in each of the first portion 41 and the third portion 43, two protrusion rows constituted by a plurality of protrusions 8 arranged discretely along the Y direction are arranged at a distance in the X direction. In each of the second portion 42 and the fourth portion 44, two protrusion rows constituted by a plurality of protrusions 8 arranged discretely along the X direction are arranged at a distance in the Y direction.

[0025] In the present disclosure, the bonding surface 61a refers to the surface of the first frame portion 61 in the case where the protrusion 8 is not formed. In other words, the plane including the bottom surface of the protrusion 8 is the bonding surface 61a.

[0026] The multiple protrusions 8 function as spacers between the vibration device 6 and the lid 3. As shown in Fig. 3A, Fig. 3B, and Fig. 4, the vibration device 6 and the lid 3 are bonded to each other by an adhesive 100 disposed in a gap formed by the multiple protrusions 8.

[0027] The number and arrangement of the protrusions 8 are not limited to the illustrated form. The multiple protrusions 8 do not have to surround the cavity 5 doubly, and may, for example, surround the cavity 5 in a single layer, or may surround the cavity 5 in three or more layers. The protrusions 8 arranged in the first portion 611, the second portion 612, the third portion 613, and the fourth portion 614 may extend along the extending direction of the first portion 611, the second portion 612, the third portion 613, and the fourth portion 614, respectively.

[0028] The cantilever 62 has a piezoelectric element 10. The cantilever 62 is configured to be vibrated in the Z direction by the piezoelectric element 10. A part of the cantilever 62 is connected to the first frame portion 61. When viewed from the Z direction, the cantilever 62 is separated from the first frame portion 61 by a slit 9 penetrating the vibration device 6 in the Z direction, except for the connection portion between the cantilever 62 and the first frame portion 61. In the following description, unless otherwise specified, a form in which the cantilever 62 is connected to the first portion 611 of the first frame portion 61 will be described.

[0029] The cantilever 62 has a rectangular shape in plan view that is approximately similar to the cavity 5. The cantilever 62 has a first edge 621, a second edge 622, a third edge 623, and a fourth edge 624. The first edge 621, the second edge 622, the third edge 623, and the fourth edge 624 form the outer periphery of the cantilever 62 in plan view.

[0030] The first edge 621 is aligned along the Y direction. The first edge 621 is a connection portion with the first portion 611 of the first frame portion 61. The second edge portion 622 is aligned along the X direction. In a plan view, the second edge portion 622 faces the second portion 612 of the first frame portion 61. The second edge portion 622 is separated from the second portion 612 by the slit 9. A portion of the slit 9 that separates the second edge portion 622 from the second portion 612 is referred to as a first portion 9a. The third edge portion 623 is aligned along the Y direction. In a plan view, the third edge portion 623 faces the third portion 613 of the first frame portion 61. A portion of the slit 9 that separates the third edge portion 623 from the third portion 613 is referred to as a second portion 9b. The fourth edge 624 is aligned along the X direction. In a plan view, the fourth edge 624 faces the fourth portion 614 of the first frame portion 61. A portion of the slit 9 that separates the third edge 623 from the third portion 613 is referred to as a third portion 9c.

[0031] The layer structure of the vibration device 6 will be described with reference to FIGS. 3A, 3B, 4, and 5. FIG.

[0032] The vibration device 6 has a vibration membrane forming layer 7. The vibration membrane forming layer 7 is formed on a support substrate 4. The vibration membrane forming layer 7 is a laminated film in which a silicon layer (active layer containing silicon) 34 and a silicon oxide film (silicon oxide layer) 35 are laminated in this order from the support substrate 4 side. The silicon layer 34 has a thickness of, for example, 20 μm. The silicon oxide film 35 has a thickness of, for example, 1.5 μm.

[0033] In the first embodiment, a first hydrogen barrier film 14A is formed on the vibration film formation layer 7. The first hydrogen barrier film 14A is made of, for example, alumina (Al 2 O 3 An example of the thickness of the first hydrogen barrier film 14A is 20 nm or more and 100 nm or less. The portion of the vibration film forming layer 7 that is included in the cantilever 62 is referred to as a vibration film 7a.

[0034] A piezoelectric element 10 is disposed on a portion of the first hydrogen barrier film 14A within the cantilever 62. The piezoelectric element 10 includes a lower electrode 11 formed on the first hydrogen barrier film 14A, a piezoelectric film 12 formed on the lower electrode 11, and an upper electrode 13 formed on the piezoelectric film 12.

[0035] The lower electrode 11 and the upper electrode 13 are formed of a thin film of a conductive metal such as platinum, molybdenum, iridium, titanium, etc. The thickness of the lower electrode 11 is, for example, 200 nm, and the thickness of the upper electrode 13 is, for example, 80 nm.

[0036] The piezoelectric film 12 is made of, for example, lead zirconate titanate (PZT). The piezoelectric film 12 may be a niobium-doped lead zirconate titanate (PNZT) film, a lanthanum-doped lead zirconate titanate (PLZT) film, a strontium barium titanate (BST) film, a strontium bismuth tantalate (SBT) film, a strontium barium niobate (SBN) film, or a lithium niobate (LiNbO 3 ) film, barium titanate (TiBaO 3 ) film, lanthanum strontium copper oxide (LSCO) film, potassium dihydrogen phosphate (KDP) film, potassium tantalum niobate (KTN) film, lead magnesium niobate titanate (PMN-PT) ceramic film, lead zinc niobate titanate (PZN-PT) ceramic film, aluminum nitride (AIN), zinc oxide (ZnO), lead titanate (PbTiO 3 ) The piezoelectric film 12 has a thickness of, for example, 2 μm.

[0037] A second hydrogen barrier film 14B is formed on the first hydrogen barrier film 14A. In the portion of the first hydrogen barrier film 14A where the piezoelectric element 10 is formed, the piezoelectric element 10 is covered with the second hydrogen barrier film 14B. The second hydrogen barrier film 14B includes, for example, an alumina film. An example of the thickness of the second hydrogen barrier film 14B is 20 nm or more and 100 nm or less. The second hydrogen barrier film 14B is provided to prevent the characteristics of the piezoelectric film 12 from deteriorating due to hydrogen reduction.

[0038] An interlayer insulating film 15 is laminated on the second hydrogen barrier film 14B. The interlayer insulating film 15 is made of, for example, a film (TEOS film) containing tetraethoxysilane (TEOS). The interlayer insulating film 15 may be made of silicon nitride (SiN) or the like. An example of the thickness of the interlayer insulating film 15 is 0.2 μm or more and 1.5 μm or less.

[0039] Hereinafter, the second hydrogen barrier film 14B and the interlayer insulating film 15 may be collectively referred to as the insulating film 20.

[0040] 6, an upper wiring 17 and a lower wiring 18 are formed on the interlayer insulating film 15. The lower wiring 18 and the upper wiring 17 are formed of, for example, a metal material including Al (aluminum). The thickness of the lower wiring 18 and the upper wiring 17 is, for example, 1 μm.

[0041] The upper wiring 17 has an upper pad portion 17a, a first wiring portion 17b, and a second wiring portion 17c. The upper pad portion 17a is disposed near a corner portion formed by a first portion 611 and a second portion 612 of the first frame portion 61 in a plan view. The upper pad portion 17a is formed to be wider than the first wiring portion 17b and the second wiring portion 17c. The first wiring portion 17b is disposed at an end portion of the interlayer insulating film 15 on the side of the first edge portion 621 of the cantilever 62. The first wiring portion 17b extends in the Y direction. The second wiring portion 17c is a portion of the upper wiring 17 that connects the upper pad portion 17a and the first wiring portion 17b.

[0042] A contact hole 19a (see FIGS. 3A, 3B, and 5) is formed between the first wiring portion 17b and the upper electrode 13, continuously penetrating the second hydrogen barrier film 14B and the interlayer insulating film 15. A part of the first wiring portion 17b enters the contact hole 19a and is connected to the upper electrode 13 within the contact hole 19a. A plurality of contact holes 19a may be formed discretely in the Y direction.

[0043] The lower wiring 18 has a lower pad portion 18a, a first wiring portion 18b, and a second wiring portion 18c. The lower pad portion 18a is disposed near a corner portion formed by the first portion 611 and the fourth portion 614 of the first frame portion 61 in a plan view. The lower pad portion 18a is formed wider than the first wiring portion 18b and the second wiring portion 18c. The first wiring portion 18b is disposed at an end portion (rear end portion) of the interlayer insulating film 15 on the connection portion side of the cantilever 62 and the first frame portion 61. The first wiring portion 18b extends in the Y direction. The first wiring portion 18b is spaced apart from the first wiring portion 17b in the X direction. The second wiring portion 18c is a portion of the lower wiring 18 that connects the lower pad portion 18a and the first wiring portion 18b.

[0044] A contact hole 19b (see FIGS. 3A, 3B, and 5) is formed between the first wiring portion 18b and the lower electrode 11, continuously penetrating the second hydrogen barrier film 14B and the interlayer insulating film 15. A part of the first wiring portion 18b enters the contact hole 19b and is connected to the lower electrode 11 within the contact hole 19b. A plurality of contact holes 19b may be formed discretely in the Y direction.

[0045] On the interlayer insulating film 15, core portions 8a included in the protrusions 8 are formed at positions corresponding to the plurality of protrusions 8. The shape of the core portions 8a is similar to that of the protrusions 8, but is smaller than the protrusions 8. The core portions 8a are made of a metal material containing aluminum (Al). The thickness of the core portions 8a is, for example, 1 μm.

[0046] A passivation film 16 is formed on the interlayer insulating film 15 so as to cover the upper wiring 17, the lower wiring 18, and the multiple core portions 8a. The passivation film 16 is made of, for example, a film (TEOS film) containing tetraethoxysilane (TEOS). The passivation film 16 may be made of silicon nitride (SiN) or the like. An example of the thickness of the passivation film 16 is 0.1 μm or more and 1.0 μm or less.

[0047] In the passivation film 16, an upper pad opening 16a that exposes a part of the upper pad portion 17a and a lower pad opening 16b (see FIG. 1) that exposes a part of the lower pad portion 18a are formed.

[0048] A plurality of core portions 8 a are covered with a passivation film 16 to form a plurality of protrusions 8 .

[0049] In the resonator device 6 having the above-mentioned layer configuration, the slit (gap) 9 is formed so as to communicate with the cavity 5 by continuously penetrating from the passivation film 16 to the silicon layer .

[0050] In the first frame portion 61, a step (first step) S1 recessed from the joint surface 61a toward the opposite side to the cover body 3 (downward in Figs. 3A, 3B, 4 and 5) is formed on the inner surface 615 facing the slit 9. Specifically, as shown in Figs. 3A and 3B, the step S1 is formed on the inner surface 613a of the third portion 613 of the first frame portion 61. As shown in Fig. 4, the step S1 is formed on the inner surface 612a of the second portion 612 of the first frame portion 61, and the step S1 is formed on the inner surface 614a of the fourth portion 614 of the first frame portion 61. The inner surface 612a faces the first portion 9a of the slit 9 and constitutes a part of the inner surface 615. The inner surface 613a faces the second portion 9b of the slit 9 and constitutes a part of the inner surface 615. The inner surface 614 a faces the third portion 9 c of the slit 9 and constitutes a part of the inner surface 615 .

[0051] In an inner surface 611a (see FIG. 6) of the first portion 611 of the first frame portion 61, a step S1 is also formed in regions on both sides of a connection portion with the cantilever 62 in a plan view. The region of the inner surface 611a of the first portion 611 where the step S1 is formed is a region facing the first portion 9a and the third portion 9c of the slit 9, and constitutes a part of the inner surface 615.

[0052] A step (second step) S2 is formed in a portion of the outer circumferential edge of the cantilever 62 facing the slit 9. Specifically, the step S2 is formed in the second edge portion 622, the third edge portion 623, and the fourth edge portion 624. The second edge 622 is an edge that faces the first portion 9a of the slit 9. The third edge 623 is an edge of the slit 9 facing the second portion 9b. The fourth edge 624 is an edge facing the third portion 9c of the slit 9.

[0053] A step S1 is formed on the inner surface 615 of the first frame portion 61 facing the slit 9, and a step S2 is formed on the outer peripheral edge of the cantilever 62 facing the slit 9. In the first embodiment, the slit 9 has an upper slit portion 91 and a lower slit portion 92 in this order from the passivation film 16 toward the silicon substrate 32. The width of the lower slit portion 92 is narrower than that of the upper slit portion 91. An example of the width of the lower slit portion 92 is 1 μm or more and 10 μm or less. The width of the lower slit portion 92 is the portion that contributes to the sound characteristics of the sound wave generating device 1.

[0054] An example of the step S1 and the step S2 will be specifically described with reference to FIG. 8. FIG. 8 is an enlarged view of the region A shown in FIG. 3A. The step S1 formed on the inner surfaces 611a, 612a, 613a, and 614a has the same configuration. The step S2 formed on the second edge portion 622, the third edge portion 623, and the fourth edge portion 624 has the same configuration. Therefore, the step S1 formed on the inner surface 613a (inner surface 615) and the step S2 formed on the third edge portion 623 will be described with reference to FIG. 8, and the description of the step S1 formed on the inner surfaces 611a, 612a, and 614a and the step S2 formed on the second edge portion 622 and the fourth edge portion 624 will be omitted.

[0055] As shown in FIG. 8, the step S1 is formed by a predetermined region of the inner surface 613a on the bonding surface 61a side being recessed toward the opposite side to the slit 9. Therefore, the corner portion formed by the inner surface 613a and the bonding surface 61a is also recessed toward the opposite side to the slit 9 compared to the case where the step S1 is not formed. The recession amount d1 is, for example, 1 μm or more and 5 μm or less. In the embodiment shown in FIG. 8, the inner surface 613a is recessed in a region of the inner surface 613a from the bonding surface 61a to the passivation film 16 formed on the silicon oxide film 35. In the first embodiment, the step S1 portion is covered with the passivation film 16.

[0056] The step S2 is formed by a predetermined region of the third edge portion 623 on the interlayer insulating film 15 side being recessed in the direction away from the slit 9. The recession amount d2 is, for example, 1 μm or more and 5 μm or less. In the embodiment shown in FIG. 8, the third edge portion 623 is recessed in a region of the third edge portion 623 from the surface of the interlayer insulating film 15 to the silicon oxide film 35.

[0057] Next, the lid body 3 will be described with reference to Figures 1, 3A, 3B, 4, 5, 8 and 9. Figure 9 is a diagram of the lid body 3 viewed from the substrate assembly 2 side. The lid body 3 is made of a silicon substrate. The lid body 3 is disposed on the substrate assembly 2 so as to cover the vibration device 6. The lid body 3 is bonded to the first frame portion 61 using an adhesive 100.

[0058] The lid body 3 has a cavity (second cavity) 3a formed by a through hole penetrating in the Z direction. The lid body 3 is frame-shaped when viewed from the Z direction. That is, the lid body 3 has a second frame portion 30. The second frame portion 30 includes a first portion 301, a second portion 302, a third portion 303, and a fourth portion 304. The first portion 301 and the third portion 303 extend along the Y direction so as to sandwich the cavity 3a between them in the X direction. The second portion 302 and the fourth portion 304 extend along the X direction so as to sandwich the cavity 3a between them in the Y direction. That is, the first portion 301, the second portion 302, the third portion 303, and the fourth portion 304 surround the cavity 3a.

[0059] The lid body 3 is configured to leave the tops of the upper pad portion 17a and the lower pad portion 18a open so that wiring can be connected to the upper pad portion 17a and the lower pad portion 18a when the lid body 3 is joined to the substrate assembly 2.

[0060] Specifically, the first portion 301 is disposed between the upper pad portion 17a and the lower pad portion 18a in a plan view. The ends of the second portion 302 and the fourth portion 304 on the first portion 301 side are located closer to the third portion 303 than the upper pad portion 17a and the lower pad portion 18a. In other words, in a plan view, the cover 3 has a shape in which two corners formed when the first portion 301 is extended to both sides of the first portion 301 in the X direction and the second portion 302 and the fourth portion 304 are extended toward the first portion 301 along the X direction have been removed.

[0061] For ease of explanation, in the following, in the lid 3, the portion that is open above the upper pad portion 17a will be referred to as an open portion 305a, and the portion that is open above the lower pad portion 18a will be referred to as an open portion 305b.

[0062] In the cover 3, a plurality of recesses 306a are formed on a joint surface (second joint surface) 306 to be joined to the first frame portion 61. In one example, as shown in FIG. 9, the plurality of recesses 306a are arranged so as to be adjacent to the protrusion 8 when viewed from the Z direction. In FIG. 9, the protrusion 8 is shown by a two-dot chain line to show the positional relationship between the recess 306a and the protrusion 8. A part of the recess 306a may overlap with the protrusion 8. In the embodiment shown in FIG. 9, in the first portion 301 of the cover 3, a plurality of recess rows are arranged in parallel in a direction perpendicular to the extension direction of the first portion 301 (X direction in FIG. 9) along the extension direction of the first portion 301. The recess row along the extension direction of the first portion 301 is a row formed by a plurality of recesses 306a arranged discretely along the extension direction of the first portion 301. 9, a plurality of recesses 306a are arranged in the second portion 302, the third portion 303, and the fourth portion 304 as in the first portion 301. The planar shape of the recesses 306a (shape viewed from the Z direction) is illustrated as a square in FIG. 9, but it may be a rectangle, another polygon, a circle, or the like.

[0063] 9, the second portion 302, the third portion 303, and the fourth portion 304 may be formed with linear recesses 306b so as to connect the recesses 306a constituting the recess row closest to the cavity 3a among the multiple recess rows. In the following, a description will be given of a configuration in which the recesses 306b are also formed. The recesses 306b may be formed in the first portion 301.

[0064] The recesses 306a and 306b are portions for allowing the adhesive 100 for bonding the lid body 3 to the first frame portion 61 to escape when bonding the lid body 3 to the first frame portion 61 as described below. The recesses 306a and 306b may be formed to have a volume that prevents the adhesive 100 from spilling out toward the slit 9 by allowing the adhesive 100 to get between them.

[0065] Next, an example of a manufacturing method of the sound wave generating device 1 according to the first embodiment will be described. The sound wave generating device 1 has a process of manufacturing a substrate assembly work-in-progress (laminate) 2A (substrate assembly work-in-progress manufacturing process), a process of manufacturing a lid 3 (lid body manufacturing process), a process of joining the substrate assembly work-in-progress 2A and the lid 3 (joining process), and a process of forming a cavity 5 in the substrate assembly work-in-progress 2A (cavity forming process). In the cavity forming process (hollow forming process), the substrate assembly work-in-progress 2A is a part for obtaining the substrate assembly 2.

[0066] <Circuit board assembly work-in-progress manufacturing process> First, the substrate assembly work-in-progress manufacturing process (laminate manufacturing process) will be described.

[0067] 10, a thermal oxidation process is performed on an SOI substrate (thermal oxidation process step). The SOI substrate includes a silicon substrate 32 as a support layer, an oxide film 33 as a BOX layer formed on the surface of the silicon substrate 32, and a silicon layer 34 as an active layer formed on the surface of the oxide film 33. By the thermal oxidation process, a silicon oxide film 35 is formed on the surface of the silicon layer 34 opposite to the oxide film 33, and a silicon oxide film 31 is formed on the surface of the silicon substrate 32 opposite to the oxide film 33.

[0068] 10 are portions that will become the support substrate 4 by being subjected to a predetermined processing in a later step, and the silicon layer 34 and the silicon oxide film 35 are portions that make up the vibration membrane forming layer 7. Therefore, if the laminated structure of the silicon oxide film 31, the silicon substrate 32, and the oxide film 33 is referred to as a substrate (first substrate) 401, an SOI substrate having the layered structure shown in FIG.

[0069] 11, a first hydrogen barrier film 14A is formed on the silicon oxide film 35 of the vibration film formation layer 7 (first hydrogen barrier film formation process). After that, a piezoelectric element 10 is formed on the first hydrogen barrier film 14A (piezoelectric element formation process). The piezoelectric element 10 is formed above a cavity formation planned region (first cavity formation planned region) 501 in a substrate 401 to become the support substrate 4.

[0070] The piezoelectric element 10 is formed, for example, as follows. A lower electrode film, which is a material film of the lower electrode 11, a piezoelectric material film, which is a material film of the piezoelectric film 12, and an upper electrode film, which is a material film of the upper electrode 13, are formed in that order on the first hydrogen barrier film 14A. Next, the upper electrode film, the piezoelectric material film, and the lower electrode film are patterned, for example, in that order, by photolithography and etching to form the upper electrode 13, the piezoelectric film 12, and the lower electrode 11. When the upper electrode 13, the piezoelectric film 12, and the lower electrode 11 are obtained from the upper electrode film, the piezoelectric material film, and the lower electrode film, the upper electrode film, the piezoelectric material film, and the lower electrode film are processed so that the upper electrode 13, the piezoelectric film 12, and the lower electrode 11 are located above the cavity formation region 501. As a result, the piezoelectric film 12 and electrodes (the lower electrode 11 and the upper electrode 13) are formed in the region above the cavity formation region 501 in the first hydrogen barrier film 14A, and the piezoelectric element 10 is formed.

[0071] 12, a second hydrogen barrier film 14B is formed on the silicon oxide film 35 to cover the exposed surface of the silicon oxide film 35 and the exposed surface of the piezoelectric element 10. The second hydrogen barrier film 14B is, for example, an alumina film. Then, the interlayer insulating film 15 is formed on the entire surface of the second hydrogen barrier film 14B. As described above, the second hydrogen barrier film 14B and the interlayer insulating film 15 may be collectively referred to as the insulating film 20. Therefore, the process of forming the second hydrogen barrier film 14B and the interlayer insulating film 15 can be referred to as an insulating film forming process.

[0072] Through the above thermal oxidation treatment process, first hydrogen barrier film formation process, piezoelectric element formation process and insulating film formation process, an intermediate laminate 101 is obtained in which a vibration film formation layer (silicon layer 34 and silicon oxide film 35), first hydrogen barrier film 14A, piezoelectric element 10 and insulating film 20 (second hydrogen barrier film 14B and interlayer insulating film 15) are stacked on a substrate 401 that is to become a support substrate 4 (intermediate laminate manufacturing process).

[0073] After the intermediate stack manufacturing process, the insulating film 20 (the second hydrogen barrier film 14B and the interlayer insulating film 15) is etched to form the contact holes 19a and 19b as shown in Fig. 13. When the contact holes 19a and 19b are formed, the insulating film 20 and the first hydrogen barrier film 14A are etched to form a groove portion 911 that is to become the upper slit portion 91 (groove forming process).

[0074] The groove portion 911 is a portion that is to become the upper slit portion 91 as described above. Therefore, the groove portion 911 is formed in the intermediate laminate 101 in the region where the slit is to be formed. Specifically, the groove portion 911 is formed along a portion other than a part of the outer periphery 501a of the region where the cavity is to be formed 501 as viewed from the Z direction. The portion of the outer periphery 501a of the region where the cavity is to be formed 501 where the groove portion 911 is not formed as viewed from the Z direction corresponds to the connection portion between the first frame portion 61 and the cantilever 62. The groove portion 911 is formed so that the outer periphery 501a of the region where the cavity is to be formed 501 is located inside the groove portion 911 as viewed from the Z direction. For example, the groove portion 911 is formed so that the outer periphery 501a is located at the center in the width direction of the groove portion 911 as viewed from the Z direction.

[0075] 14A and 14B, a wiring film, which is a material film for the upper wiring 17 and the lower wiring 18, is formed on the interlayer insulating film 15 including the contact holes 19a, 19b. The wiring film is patterned by photolithography and etching to form the upper wiring 17 and the lower wiring 18, and to form a plurality of core portions 8a outside the groove portion 911. The plurality of core portions 8a are formed at the positions where the plurality of protrusions 8 are arranged. As described above, the core portions 8a are formed from the wiring film, and therefore the core portions 8a can also be called dummy wiring portions.

[0076] Next, a passivation film 16 is formed on the interlayer insulating film 15 so as to cover the upper wiring 17, the lower wiring 18, and the multiple core portions 8a. The interlayer insulating film 15 and the passivation film 16 are, for example, a TEOS film containing tetraethoxysilane (TEOS).

[0077] As described above, the multiple core portions 8a are also covered with the passivation film 16, thereby obtaining the multiple protrusions 8. Therefore, the protrusions 8 are formed by the step of forming the core portions 8a and the step of forming the passivation film 16 (protrusion forming step).

[0078] As shown in Figures 15A and 15B, by photolithography and etching, an upper pad opening 16a that exposes a portion of the upper pad portion 17a and a lower pad opening 16b that exposes a portion of the lower pad portion 18a are formed in the passivation film 16.

[0079] Furthermore, by photolithography and etching, the passivation film 16 is removed from the region above the cavity formation region 501 except for the region covering the upper wiring 17 and the lower wiring 18, thereby exposing the interlayer insulating film 15. This process may be omitted.

[0080] Furthermore, a through hole 912 penetrating the intermediate stack 101 is formed in part of the bottom surface 911a of the groove 911 by photolithography and etching. The through hole 912 is formed so as to further penetrate the oxide film 33.

[0081] Specifically, a through hole 912 is formed that penetrates continuously from the bottom surface 911a through the vibration membrane forming layer 7 (silicon oxide film 35 and silicon layer 34) and the oxide film 33 to reach the silicon substrate 32. The through hole 912 is a portion that is to become the lower slit portion 92. Therefore, the through hole 912 is formed so that the width of the through hole 912 is the width of the lower slit portion 92.

[0082] By forming the through-holes 912 as described above, the slits 9 are formed. By forming the slits 9, the first frame 61 and the cantilever 62 are obtained. In other words, the vibration device 6 having the first frame 61 and the cantilever 62 is obtained. As a result, the substrate assembly work-in-progress 2A is obtained as a laminate in which the vibration device 6 is laminated on the substrate 401.

[0083] The through hole 912 is formed in a part of the bottom surface 911a of the groove portion 911. Therefore, the width of the groove portion 911 is wider than the width of the through hole 912. Thus, the slit 9 obtained by forming the through hole 912 as described above has an upper slit portion 91 and a lower slit portion 92. By forming the slit 9 using the groove portion 911 and the through hole 912 as described above, steps S1 and S2 are also formed in the substrate assembly work-in-progress 2A. Since the through hole 912 is formed after the formation of the passivation film 16, the surface of the step S1 is composed of the passivation film 16.

[0084] <Lid manufacturing process> Next, the lid manufacturing process will be described. The order of the lid manufacturing process and the substrate assembly work-in-progress manufacturing process is not limited.

[0085] As shown in FIG. 16, a substrate (second substrate) 70 to become the lid 3 having the cavity 3a is prepared. The substrate 70 has a silicon substrate 71, a first oxide film 72 formed on the front surface of the silicon substrate 71, and a second oxide film 73 formed on the back surface (the surface opposite to the front surface) of the silicon substrate 71. The substrate 70 is formed by subjecting the silicon substrate to a thermal oxidation treatment. Specifically, the silicon substrate is subjected to a thermal oxidation treatment, so that the first oxide film 72 and the second oxide film 73 are formed on the front surface and the back surface. In the thermally oxidized silicon substrate, the portion between the first oxide film 72 and the second oxide film 73 is the silicon substrate 71.

[0086] As shown in Figures 17A and 17B, openings 72a, 72b, and 72c are formed by removing the first oxide film 72 around island regions 721a, 721b, and 721c by photolithography and etching, so as to leave island regions 721a, 721b, and 721c in the first oxide film 72. Similarly, by photolithography and etching, the first oxide film 72 around the island regions 731a, 721b, and 721c is removed so as to leave the island regions 731a, 731b, and 731c in the second oxide film 73, thereby forming openings 72a, 72b, and 72c.

[0087] The outer peripheral edges of openings 72a and 73b coincide with outer peripheral edge 308a of planned cavity formation region 308 in substrate 70. The outer peripheral edges of openings 72b and 73b coincide with the outer peripheral edge of planned cavity formation region 308 in substrate 70. The outer peripheral edges of openings 72c and 73c coincide with the outer peripheral edge of planned cavity formation region 305b (see FIG. 1).

[0088] Next, as shown in FIGS. 18A and 18B, a through hole 73d1 to become the recess 306a and a through hole 73d2 to become the recess 306b are formed in the second oxide film 73 by photolithography and etching.

[0089] 19, a support substrate 82 is attached onto the first oxide film 72 via a release layer 81. A resist film 83 is formed on the second oxide film 73. At this time, a part of the resist film 83 is also filled into the through hole 73d.

[0090] 20, the silicon substrate 71 is etched using the resist film 83 as a mask to form a through hole 75 that penetrates the silicon substrate 71 from the opening 73a to the opening 72a. Similarly, a through hole (not shown) that penetrates the substrate 70 from the opening 73b to the opening 72b, and a through hole (not shown) that penetrates the silicon substrate 71 from the opening 73c to the opening 72c are formed.

[0091] 21, after removing the resist film 83, the silicon substrate 71 is etched using the second oxide film 73 as a mask. As a result, the through holes 73d1 and 73d2 are extended toward the silicon substrate 71, and the recesses 306a and 306b are formed.

[0092] Thereafter, the support substrate 82 and the release layer 81 are peeled off from the substrate 70. Since the island region 721a is separated from the surroundings by the through-hole 75, the region of the silicon substrate 71 corresponding to the island region 721a is removed together with the support substrate 82. As a result, a cavity 3a is formed in the substrate 70. By peeling the support substrate 82 off from the substrate 70, the regions of the silicon substrate 71 corresponding to the island regions 721b and 721c are removed together with the support substrate 82. As a result, the openings 305a and 305b are formed. Thereafter, the first oxide film 72 and the second oxide film 73 are removed, thereby obtaining the lid 3 shown in FIG. 22.

[0093] <Joining process> In the bonding process, as shown in FIG. 23, adhesive 100 is applied to the area of ​​the surface (bonding surface 306) of the lid body 3 on which the recesses 306a and 306b are formed, other than the recesses 306a and 306b, and the lid body 3 is fixed to the substrate assembly work-in-progress 2A.

[0094] (Cavity formation process) In the cavity forming step, the silicon oxide film 31 and the silicon substrate 32 of the substrate assembly work-in-progress 2A are polished to thin the silicon substrate 32. Then, a resist mask (not shown) corresponding to the region where the cavity is to be formed is formed on the lower surface of the silicon substrate 32, and the silicon substrate 32 is etched from the lower surface. This forms the cavity 5. As a result, a sound wave generating device 1 (see FIGS. 1, 2, 3A, 3B, 4, and 5) including a support substrate 4, a vibration device 6, and a cover 3 is obtained.

[0095] The cavity forming step may be performed by laminating a support substrate to the lid 3. In this case, after the cavity 5 is formed, the support substrate is peeled off, thereby obtaining the sound wave generating device 1.

[0096] The sound wave generating device 1 according to the first embodiment includes a support substrate 4 having a cavity 5, a vibration device 6 supported by the support substrate, and a lid body 3 having a hollow 3a and bonded to the vibration device 6 with an adhesive 100. The vibration device 6 includes a first frame portion 61 surrounding the cavity 5 as viewed from the lid body 3 and having a bonding surface 61a bonded to the lid body 3 with the adhesive 100, and a cantilever (vibration portion) 62 facing the cavity 5 and having a piezoelectric element 10. The cantilever 62 has a first edge portion 621, which is a part of the cantilever 62, connected to the first frame portion 61. When viewed from the bonding direction (corresponding to the Z direction) of the vibration device 6 and the lid body 3, a portion of the cantilever 62 other than the connection portion (the first edge portion 621) of the cantilever 62 and the first frame portion 61 is separated from the first frame portion 61 by a slit 9 penetrating the vibration device 6 in the bonding direction. The lid 3 has a second frame 30 that surrounds the cavity 3a and includes a bonding surface 306 that is bonded to the bonding surface 306 by an adhesive 100. The cavity 5 and the cavity 3a communicate with each other through a slit 9. A protrusion 8 that protrudes toward the bonding surface 306 is formed on the bonding surface 306. A step S1 that is recessed from the bonding surface 61a toward the opposite side to the lid 3 is formed on an inner surface 615 of the first frame 61 that faces the slit 9.

[0097] As described above, in the sound wave generating device 1, the cantilever 62 arranged opposite the cavity 5 is connected to the first frame 61 at the first edge 621. The second edge 622, the third edge 623, and the fourth edge 624 of the cantilever 62 are separated from the first frame 61 by the slits 9. That is, in the cantilever 62, the connection between the first edge 621 and the first frame 61 is a fixed end, and the end opposite to the fixed end in the X direction is a free end. Since the cantilever 62 has the piezoelectric element 10, the vibration device 6 vibrates in the Z direction by applying a driving voltage to the piezoelectric element 10. This vibration vibrates the air, generating sound waves.

[0098] In the sound wave generating device 1, a lid 3 is joined to a substrate assembly 2 including a vibration device 6. A cavity 3a is formed in the lid 3, which communicates with the cavity 5 via a slit 9. Due to the formation of the cavity 3a, the vibration of the cantilever 62 is not hindered even when the lid 3 is joined to the substrate assembly 2. As shown in FIG. 3A, when the cavity 3a is formed so as to penetrate the lid 3, the area of ​​the lid 3 corresponding to the cavity 3a on the surface (upper surface) opposite to the joining surface 306 is open.

[0099] Therefore, in the sound wave generating device 1 equipped with the lid 3, the sound generated by the vibration of the cantilever 62 is emitted to the outside through the opening 5a on the lower surface side of the cavity 5 and the hollow 3a.

[0100] In the sound wave generating device 1, the lid 3 is joined to the substrate assembly 2, thereby preventing air leakage and improving the sound characteristics of the sound wave generating device 1. The provision of the lid 3 protects the vibration device 6. Furthermore, the provision of the lid 3 improves the rigidity of the chip.

[0101] The lid 3 is bonded to the substrate assembly 2 (specifically, the vibration device 6) by the adhesive 100. As described in the example of the manufacturing method of the sound wave generating device 1, when the lid 3 and the substrate assembly 2 are bonded, the adhesive 100 is applied to the bonding surface 306 of the lid 3, and the lid 3 is attached to the vibration device 6. In this case, for example, the closer the distance between the bonding surface 306 and the bonding surface 61a, the more the adhesive 100 protrudes from the bonding portion between the bonding surface 306 and the bonding surface 61a. In the sound wave generating device 1 that generates sound by the vibration of the cantilever 62, it is desired that the width of the slit 9 is small from the viewpoints of preventing sound leakage and low-frequency characteristics. Therefore, if the amount of the adhesive 100 protruding toward the slit 9 is large, there is a risk that the adhesive 100 and the cantilever 62 will interfere with each other.

[0102] A protrusion 8 is formed on the joint surface 61a of the vibration device 6 according to the first embodiment. The protrusion 8 functions as a spacer that defines the distance between the joint surface 61a and the joint surface 306 of the lid 3, or as a stopper that prevents the joint surface 306 from approaching the joint surface 61a by a certain distance or more when the lid 3 is joined to the substrate assembly 2. In this case, the distance between the joint surface 61a and the joint surface 306 is longer than when the protrusion 8 is not formed. Therefore, more adhesive 100 can be present between the joint surface 61a and the joint surface 306, so that the amount of adhesive 100 that protrudes toward the slit 9 can be reduced.

[0103] Furthermore, in an area of ​​the inner surface 615 (specifically, the inner surfaces 611a, 612a, 613a, and 614a) of the first frame portion 61 of the vibration device 6 facing the slit 9, a step S1 recessed downward (toward the support substrate 4) from the bonding surface 61a is formed. At the corner portion (the inner edge portion of the bonding surface 61a) between the step S1 and the bonding surface 61a, the adhesive 100 is prevented from overflowing to the slit 9 side as shown in FIG. 8 due to the surface tension of the adhesive 100. In other words, by providing the step S1, the stopping position of the adhesive 100 toward the slit 9 side can be specified. Furthermore, even if a part of the adhesive 100 flows into the step S1, it is possible to stop the adhesive 100 at the bottom (or lower part) side of the step S1.

[0104] Therefore, in the sound wave generating device 1 including the vibration device 6 in which the convex portion 8 and the step S1 are formed, the adhesive 100 is less likely to protrude toward the slit 9. This makes it possible to properly secure a gap between the first frame portion 61 and the cantilever 62 separated by the slit 9. This makes it possible to prevent interference between the adhesive 100 and the cantilever 62 described above. Since the adhesive 100 is prevented from protruding toward the slit 9, it is also possible to narrow the width of the slit 9. As a result, sound leakage can be better prevented and the characteristics of the low-frequency range can also be improved.

[0105] An example of a manufacturing method for the sound wave generating device 1 of the first embodiment includes a substrate assembly work-in-progress manufacturing process (laminate manufacturing process) for manufacturing a substrate assembly work-in-progress 2A, which is a laminate of a substrate 401 to become the support substrate 4 and a vibration device 6, a lid body manufacturing process for manufacturing a lid body 3, a joining process for joining the lid body 3 to the vibration device 6, and a cavity formation process (hollow formation process) for forming a cavity 5 in a region 501 in the substrate 401 where the cavity is to be formed. The substrate assembly work-in-progress manufacturing process includes the steps of: forming an intermediate laminate 101 having a vibration membrane forming layer 7 stacked on a substrate 401, a piezoelectric element 10 provided above a region 501 in the vibration membrane forming layer 7 where a cavity is to be formed, and an insulating film 20 covering the piezoelectric element 10 and the vibration membrane forming layer 7; forming a groove portion 911 from the insulating film 20 side along the outer peripheral edge 501a of the region 501 in which a cavity is to be formed in the intermediate laminate 101 except for a portion of the outer peripheral edge 501a; forming a convex portion 8 in the insulating film 20 outside the region 501 in which a cavity is to be formed; and forming a through hole 912 that penetrates the intermediate laminate 101 in a portion of the bottom surface 911a of the groove portion 911, thereby separating the intermediate laminate 101 into a cantilever (vibration portion) 62 including the piezoelectric element 10 and a first frame portion 61 that is connected to a portion of the cantilever 62 and surrounds the cantilever 62, thereby obtaining a vibration device 6. The lid body manufacturing process includes a process of obtaining the lid body 3 by forming a cavity 3a in the substrate 70 to be the lid body 3, the cavity 3a being in communication with the cavity 5 through the groove 911 and the through hole 912. In the bonding process, an adhesive 100 is applied to a bonding surface 306 of the lid body 3 to be bonded to the vibration device 6, and the lid body 3 is bonded to the surface (bonding surface 61a) of the vibration device 6 on which the convex portion 8 is formed, thereby bonding the lid body 3 and the vibration device 6. In the cavity forming process, the cavity 5 is formed in the substrate 401, thereby obtaining a support substrate 4 in which the cavity 5 is formed.

[0106] In the above-described exemplary method for manufacturing the sound wave generating device 1, the sound wave generating device 1 having the above-described functions and effects is obtained.

[0107] In the sound wave generating device 1 according to an embodiment, the cover 3 may have a recess 306a as shown in FIG. 3A, FIG. 3B, FIG. 4, FIG. 5, and FIG. 9. In this case, a part of the adhesive 100 can enter the recess 306a. Therefore, when the cover 3 is joined to the substrate assembly 2 (specifically, the vibration device 6) with the adhesive 100 applied to the joining surface 306, the recess 306a functions as a part for letting off a part of the adhesive 100. As a result, the adhesive 100 is less likely to overflow toward the slit 9. In a form in which the recess 306b is formed in the vicinity of the slit 9 (or in the vicinity of the cavity 3a) of the joining surface 306 as viewed from the Z direction, the adhesive 100 pushed out toward the slit 9 by the joining surface 306 and the protrusion 8 approaching each other is more likely to be prevented from overflowing toward the slit 9.

[0108] In the sound wave generating device 1 and the manufacturing method thereof, a silicon oxide layer may be formed in the active layer containing silicon. When manufacturing the sound wave generating device 1 of such a form, a SOI substrate that has been thermally oxidized and has a silicon oxide film 35 on a silicon layer 34 as shown in FIG. 10 can be used. When the active layer containing silicon is the silicon layer 34 in the above embodiment and the silicon oxide layer is the silicon oxide film 35, the effect of forming a silicon oxide layer in the active layer containing silicon will be described.

[0109] In the sound wave generating device 1 having the silicon oxide film 35 on the silicon layer 34, as shown in Figs. 3A, 3B, 4 and 5, the slit 9 penetrates the silicon oxide film 35 and the silicon layer 34 and communicates with the cavity 5. In order to improve the sound characteristics (especially the characteristics in the low frequency range), it is better for the width of the slit 9 to be narrow. In the embodiment having the silicon oxide film 35 on the silicon layer 34, it is easier to control the width of the slit 9 (specifically the lower slit portion 92) than when the silicon oxide film 35 is not present on the silicon layer 34. This point will be explained with reference to Figs. 24 and 25. Fig. 24 is a diagram for explaining a reference example of a method for forming a hole in a silicon layer. Fig. 25 is a diagram for explaining a method for forming a hole in a silicon layer when a silicon oxide layer is present on the silicon layer. Figs. 24 and 25 show a state after the hole H1 is formed by the method explained with reference to Figs. 24 and 25.

[0110] First, as shown in FIG. 24, a method (reference example) for forming a hole H on a silicon layer 34 when there is no silicon oxide film 35 on the silicon layer 34 will be described. In this case, a resist film R is formed on the silicon layer 34 as shown by the dashed line so as to expose a hole formation region 34a in the silicon layer 34 corresponding to the hole H to be formed (hole H shown by the dashed line in FIG. 24). The silicon layer 34 is etched using the resist film R as a mask. In this case, during the etching process, the resist film R is also partially removed as a mask as shown by the solid line. As a result, a hole H (hole shown by the solid line) wider than the desired hole H shown by the dashed line is formed.

[0111] Next, as shown in Fig. 25, an example of a method for forming holes H in the silicon layer 34 and the silicon oxide film 35 will be described when the silicon oxide film 35 is stacked on the silicon layer 34. In Fig. 25 as well, the hole formation region is referred to as hole formation region 34a.

[0112] In this case, a resist film R is formed on the silicon oxide film 35 as shown by the dashed line so as to expose a hole formation region 34a corresponding to the hole H to be formed in the laminate of the silicon layer 34 and the silicon oxide film 35. The silicon oxide film 35 and the silicon layer 34 are successively etched using the resist film R as a mask. Even in this case, the resist film R is also partially removed as a mask during the etching process as shown by the solid line. However, since the silicon oxide film 35 has a higher selectivity than the resist film R, the desired hole H is formed in the silicon oxide film 35 before the resist film R is partially etched. In this way, when the desired hole H is formed in the silicon oxide film 35, the silicon oxide film 35 functions as a mask against the etching of the silicon layer 34. As a result, a hole H closer to the desired hole H is formed.

[0113] As described above, in the sound wave generating device 1, the adhesive 100 is prevented from spilling out, so the slit width can be narrowed. In the form of the sound wave generating device 1 including the silicon oxide film 35 laminated on the silicon layer 34, as explained with reference to FIG. 25, the slit 9 (specifically, the lower slit portion 92) can be formed in a shape close to the desired shape. In other words, even a narrower slit 9 can be formed with high precision, so that the sound characteristics can be improved.

[0114] Second embodiment Fig. 26 is a plan view of a sound wave generating device (transducer) according to a second embodiment. Fig. 27 is a cross-sectional view of the sound wave generating device taken along line XXVII-XXVII in Fig. 26. Fig. 28 is a view of a cover body 3A according to the second embodiment as viewed from the substrate assembly side.

[0115] The sound wave generating device 1A according to the second embodiment includes a board assembly 2 and a cover body 3A. The sound wave generating device 1A differs from the sound wave generating device 1A according to the first embodiment in that the sound wave generating device 1A includes a cover body 3A instead of the cover body 3. The configuration of the board assembly 2 included in the sound wave generating device 1A according to the second embodiment is the same as that of the board assembly 2 described in the first embodiment. Therefore, a description of the board assembly 2 will be omitted.

[0116] The cover 3A is different from the cover 3 in the first embodiment mainly in that a step (second step) S3 is formed on the inner surface of the cover 3A facing the cavity 3a. The cover 3A will be described focusing on this point. In the cover 3A according to the second embodiment, a mode in which the recess 306b (see FIG. 9) is not formed will be described, but the recess 306b may be formed in the cover 3A.

[0117] The lid body 3A has a cavity 3a. The lid body 3A has a first portion 301, a second portion 302, a third portion 303, and a fourth portion 304 surrounding the cavity 3a. The positional relationship between the first portion 301, the second portion 302, the third portion 303, and the fourth portion 304 is the same as in the first embodiment.

[0118] The inner surface 301a of the first portion 301, the inner surface 302a of the second portion 302, the inner surface 303a of the third portion 303, and the inner surface 304a of the fourth portion 304 are inner surfaces facing the cavity 3a and are also side surfaces of the cavity 3a. A step S3 is formed on the inner surfaces 301a, 302a, 303a, and 304a. The step S3 of the inner surfaces 301a, 302a, 303a, and 304a has the same configuration. Therefore, as shown in FIG. 27, the step S3 of the inner surface 303a will be taken as an example to explain the step S3.

[0119] 27, the step S3 is formed on the inner surface 303a so as to be recessed from the bonding surface 306 toward the opposite side to the substrate assembly 2. Therefore, a predetermined area of ​​the inner surface 303a from the bonding surface 306 (the area where the step S3 is formed) is recessed toward the opposite side to the cavity 3a (outside). The recession amount d3 (see FIG. 28) may be the same as the recession amount d1 of the inner surface 613a.

[0120] As shown in Fig. 28, a plurality of recesses 306a are formed on the joint surface 306 of the lid body 3A. Although Fig. 28 illustrates the case where there is one recess row as described with reference to Fig. 9, a plurality of recess rows may be formed.

[0121] An example of a method for manufacturing the sound wave generating device 1A including the lid 3A is the same as the method for manufacturing the sound wave generating device 1 described in the first embodiment, except for the lid manufacturing process. Therefore, the lid manufacturing process will be described and the description of the other processes will be omitted.

[0122] In the lid manufacturing process according to the second embodiment, similarly to the first embodiment, a substrate 70 to become the lid 3 having a cavity 3a is prepared as shown in Fig. 14B. The substrate 70 has a silicon substrate 71, a first oxide film 72 formed on the front surface of the silicon substrate 71, and a second oxide film 73 formed on the back surface (the surface opposite to the front surface) of the silicon substrate 71. In the processing of the substrate 70 described below, the points related to the formation of the openings 305a, 305b are the same as those in the first embodiment, and therefore the description will be omitted as appropriate.

[0123] Next, as shown in FIG. 29, the first oxide film 72 is removed around the island region 721a by photolithography and etching so as to leave the island region 721a in the first oxide film 72, thereby forming an opening 72a. The first oxide film 72 is removed around the island region 731a by photolithography and etching so as to leave the island region 731a in the second oxide film 73, thereby forming the opening 72a. In the second embodiment, the opening 72a is formed so that the outer periphery of the opening 72a coincides with the outer periphery 308a of the cavity formation region 308 in the substrate 70, while the opening 73a is formed so that the outer periphery of the opening 73b is located outside the outer periphery 308a. The opening 73a is formed so that the amount of deviation between the outer periphery of the opening 73a and the outer periphery 308a of the cavity formation region 308 is the above-mentioned recession amount d3 at the step S3.

[0124] Next, in the same manner as in the first embodiment, a through hole 73d1 that is to become the recess 306a is formed in the second oxide film 73 by photolithography and etching.

[0125] Thereafter, as shown in FIG. 30, a support substrate 82 is bonded onto the first oxide film 72 via a peeling layer 81. A resist film 83 is formed on the second oxide film 73. At this time, a part of the resist film 83 is also filled into the through hole 73d. In the second embodiment, the resist film 83 is formed so as to cover the outer periphery of the opening 73a. More specifically, the resist film 83 is formed so as to fill the gap between the outer periphery of the opening 73a and the outer periphery 308a. Next, the silicon substrate 71 is etched using the resist film 83 as a mask, thereby forming a through hole 75 that penetrates the silicon substrate 71 from the opening 73a to the opening 72b, as shown in FIG. 31.

[0126] Next, after removing the resist film 83, the silicon substrate 71 is etched using the second oxide film 73 as a mask, whereby the through hole 75 is extended toward the silicon substrate 71, and a recess 306a is formed.

[0127] Next, the support substrate 82 and the release layer 81 are peeled off from the substrate 70. Since the island region 721a is separated from the surroundings by the through-hole 75, the region of the silicon substrate 71 corresponding to the island region 721a is removed together with the support substrate 82. As a result, the cavity 3a is formed in the substrate 70, and the cavity 3a is also formed. At this stage, the openings 305a and 305b are also formed as in the first embodiment. As a result, the lid 3A shown in FIGS. 26 to 28 is obtained.

[0128] The bonding step and the cavity forming step described in the first embodiment are carried out using the lid body 3A manufactured as described above and the substrate assembly work-in-progress 2A described in the first embodiment, resulting in a sound wave generating device 1A equipped with the lid body 3A.

[0129] The configuration of the sound wave generating device 1A is the same as that of the sound wave generating device 1 except for having the step S3, and therefore the sound wave generating device 1A has the same effects as the sound wave generating device 1. The same also applies to the effects of the manufacturing method for the sound wave generating device 1A.

[0130] In the sound wave generating device 1A, the lid 3A has a step S3. Therefore, when the lid 3A coated with the adhesive 100 is bonded to the vibration device 6, the adhesive 100 flowing toward the slit 9 along the bonding surface 306 of the lid 3A can escape to the step S3. As a result, the adhesive 100 can be prevented from spilling out toward the slit 9.

[0131] In a configuration in which a vibration device 6 having a step S1 and a lid body 3A having a step S3 are joined with adhesive 100, measures are taken to prevent the adhesive 100 from overflowing from both the vibration device 6 and the lid body 3A, making it even less likely that the adhesive 100 will overflow toward the slit 9.

[0132] Third embodiment Fig. 32 is a plan view of a sound wave generating device (transducer) according to a third embodiment, Fig. 33 is a cross-sectional view of the sound wave generating device taken along line XXXIII-XXXIII in Fig. 32.

[0133] The sound wave generating device 1B according to the third embodiment includes a substrate assembly 2B and a lid body 3A. The lid body 3A is the same as the lid body 3A described in the second embodiment. Therefore, the description of the lid body 3A will be omitted.

[0134] The substrate assembly 2B differs from the substrate assembly 2 mainly in that it does not have the steps S1 and S2. That is, the substrate assembly 2B includes a support substrate 4 having a cavity 5, and a vibration device 6A. The configuration of the vibration device 6A is the same as that of the vibration device 6, except that the step S1 is not formed in the slit 9 of the inner surface (inner surfaces 611a, 612a, 613a, 614a) of the first frame portion 61, and the step S2 is not formed in the second edge portion 622, the third edge portion 623, and the fourth edge portion 624 of the outer periphery of the cantilever 62.

[0135] Since the steps S1 and S2 are not formed, the width of the slit 9 is uniform in the direction in which the slit 9 extends (Z direction).

[0136] The sound wave generating device 1B is manufactured, for example, as follows.

[0137] Among the laminate manufacturing steps described in the first embodiment, the step of forming the groove portion 911 described with reference to FIG. 13 is omitted, and in the step of forming the through hole 912 described with reference to FIG. 14B, the through hole 912 is formed so as to penetrate from the passivation film 16 to the silicon oxide film 35 to obtain the slit 9, thereby manufacturing a substrate assembly work-in-progress 2A for the sound wave generating device 1B. Furthermore, a lid body 3A is manufactured in the same manner as in the second embodiment. The bonding step and the cavity forming step described in the first embodiment are performed on the substrate assembly work-in-progress 2A and the lid body 3A manufactured in this manner, thereby manufacturing a sound wave generating device 1C.

[0138] In the sound wave generating device 1B, since the vibration device 6A has the convex portion 8, the adhesive 100 is unlikely to overflow toward the slit 9 as described in the first embodiment. Furthermore, the lid body 3A of the sound wave generating device 1C has a step S3. Therefore, as described in the second embodiment, the step S3 suppresses overflow of the adhesive 100 toward the slit 9. Therefore, in the sound wave generating device 1B including the vibration device 6A with the convex portion 8 and the lid body 3A with the step S3, overflow of the adhesive 100 toward the slit 9 is unlikely to occur. Therefore, it is possible to prevent the above-mentioned adhesive 100 from interfering with the cantilever 62. Since overflow of the adhesive toward the slit 9 is suppressed, it is also possible to narrow the width of the slit 9. As a result, sound leakage can be further prevented, and the characteristics of the low frequency range can also be improved.

[0139] In the sound wave generating device 1B, a recess 306a may be formed in the cover 3A. The effect of forming the recess 306a is the same as in the first embodiment.

[0140] (Fourth embodiment) Fig. 34 is a plan view of a sound wave generating device (transducer) according to a fourth embodiment, Fig. 35 is a cross-sectional view of the sound wave generating device taken along line XXXV-XXXV in Fig. 34.

[0141] The sound wave generating device 1C according to the fourth embodiment includes a board assembly 2B and a cover 3B. The board assembly 2B is the same as the board assembly 2B described in the third embodiment. Therefore, the description of the board assembly 2B will be omitted.

[0142] When viewed from the Z direction, the lid body 3B differs from the lid body 3A according to the second embodiment (or the third embodiment) in that the size of the hollow 3a is larger than the cavity 5. The lid body 3B will be described focusing on this difference.

[0143] The cover 3B has a first portion 301, a second portion 302, a third portion 303, and a fourth portion 304 which surround the cavity 3a. The positional relationship between the first portion 301, the second portion 302, the third portion 303, and the fourth portion 304 is the same as in the first embodiment.

[0144] An inner surface 301a of the first portion 301, an inner surface 302a of the second portion 302, an inner surface 303a of the third portion 303, and an inner surface 304a of the fourth portion 304 are inner surfaces facing the cavity 3a and are also side surfaces of the cavity 3a.

[0145] As described above, the size of hollow 3a is larger than cavity 5 when viewed from the Z direction. This point will be described from the viewpoint of the positional relationship between inner surfaces 301a, 302a, 303a, and 304a (corresponding to the side surfaces of hollow 3a) when viewed from the Z direction and inner surfaces 411, 421, 431, and 441 corresponding to the side surfaces of cavity 5 of support substrate 4. The description of the positional relationship is based on the state viewed from the Z direction.

[0146] The inner surface 301a is recessed outward from the inner surface 411. The inner surface 301b is recessed outward from the inner surface 421. The inner surface 301c is recessed outward from the inner surface 431. The inner surface 301d is recessed outward from the inner surface 441. An example of the recession amount d4 (see FIG. 34) of the inner surfaces 301a, 301b, 301c, and 301d from the corresponding inner surfaces 411, 421, 431, and 441 is 1 μm or more and 10 μm or less. The recession amounts of the inner surfaces 301a, 301b, 301c, and 301d from the corresponding inner surfaces 411, 421, 431, and 441 may be the same or different.

[0147] The lid 3B is manufactured in the lid manufacturing process in the second embodiment by forming the region in which the hollow is to be formed larger than the region in which the cavity is to be formed 501. The lid 3B manufactured in this manner and the substrate assembly work-in-progress 2A manufactured as described in the third embodiment are subjected to the bonding process and the cavity forming process described in the first embodiment to manufacture the sound wave generating device 1C.

[0148] In the sound wave generating device 1C, since the vibration device 6C has a convex portion 8, the adhesive 100 toward the slit 9 is unlikely to overflow as described in the first embodiment. Furthermore, the hollow 3a of the cover 3A included in the sound wave generating device 1C is larger than the cavity 5. In this case, as shown in FIG. 35, even if the adhesive 100 toward the hollow 3a escapes along the inner surface 303a toward the opposite side to the joining surface 306, the size of the hollow 3a considering the thickness of the adhesive 100 attached to the inner surface 303a approaches the size of the cavity 5. Therefore, it is possible to prevent the adhesive 100 attached to the inner surface 303a from interfering with the cantilever 62. Here, the adhesive 100 attached to the inner surface 303a has been described as an example, but the same applies to the inner surfaces 301a, 302a, and 304a. As a result, sound leakage can be prevented and at least the characteristics of the low frequency range can be maintained.

[0149] Although the embodiment and modified examples according to the present disclosure have been described above, the present invention is not limited to the exemplified embodiment. The present invention is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0150] (Variation 1) For example, in the above embodiment, the sound wave generating device 1 is described as including one vibration device 6, but the configuration of the sound wave generating device is not limited to this. The sound wave generating device may include multiple (for example, a pair of) vibration devices.

[0151] Fig. 36 is a plan view of a sound wave generating device 1D according to Modification 1. Fig. 37 is a cross-sectional view of the sound wave generating device 1D taken along line XXXVII-XXXVII in Fig. 36. Fig. 38 is a cross-sectional view of the sound wave generating device 1 taken along line XXXIII-XXXIII in Fig. 36.

[0152] As shown in Figs. 36 to 38, the sound wave generating device 1D includes two (a pair) vibration devices 6, 6. The sound wave generating device 1D corresponds to a form in which the vibration device 6 is connected to the third portion 613 of the first frame portion 61 in the first embodiment, similar to the vibration device 6 connected to the first portion 611 in the first embodiment. In Figs. 36 and 37, the portions corresponding to the first portion 611 and the third portion 613 in the first embodiment are referred to as a 1A portion 611A and a 1B portion 611B. The pair of vibration devices 6, 6 are arranged such that the free ends face each other. The portion between the free ends of the pair of vibration devices 6, 6 can be regarded as a part of the slit 9.

[0153] In particular, as shown in Fig. 38, the configurations of the second portion 612 and the fourth portion 614 are the same as those of the first embodiment. Therefore, the sound wave generating device 1D has the same effects as the sound wave generating device 1.

[0154] (Variation 2) Like the convex portion 8A shown in FIG. 39, the shape of the convex portion formed on the joining surface 61a may be hexagonal. FIG. 39 is a drawing for explaining the second modification, and is a drawing showing an enlarged portion of the third portion 613. The plurality of convex portions 8A may be arranged in a row along the extending direction of the third portion 613, and may be arranged in parallel along a direction perpendicular to the extending direction of the third portion 613. As shown in FIG. 39, one of two adjacent convex portion rows along a direction perpendicular to the extending direction of the third portion 613 may be shifted from the other row along the extending direction of the third portion 613. The above-mentioned convex portion row is formed by a plurality of convex portions 8A discretely arranged along the extending direction of the third portion 613.

[0155] 39 also illustrates a modified example of a recess formed on the joint surface 306 of the lid 3. The recess 306c illustrated in FIG. 39 is formed on the joint surface 306 of the lid 3 as described above, but in order to explain the positional relationship with the protrusion 8A, the recess 306c is indicated by a two-dot chain line in FIG. 39. As shown in FIG. 39, the shape of the recess 306c in plan view may also be hexagonal. When viewed from the Z direction, the multiple recesses 306c may be formed adjacent to the protrusion 8A, but some of the multiple recesses 306a may be formed to cover the protrusion 8A.

[0156] A protruding portion 8B extending along the extending direction of the third portion 613 may be formed near the inner surface 613a of the third portion 613. A recessed portion 306c partially overlapping with the protruding portion 8B when viewed from the Z direction may have a shape in which a part of a hexagon has been cut out.

[0157] Using Figure 39, we have explained modified examples of the convex portion formed on the third portion 613 and the concave portion formed on the third portion 303 of the lid body 3, but similar modifications of the convex portion can also be applied to the convex portions formed on the first portion 611, the second portion 612 and the fourth portion 614, and similar modifications of the concave portion can also be applied to the concave portions formed in the first portion 301, the second portion 302 and the fourth portion 304 of the lid body 3.

[0158] Modifications other than the above-mentioned modifications 1 and 2 are also possible. For example, the lid body does not need to have a recess for allowing the adhesive to escape.

[0159] For example, application examples of the transducer are not limited to sound wave generating devices (speakers or ultrasonic wave generating devices) and may be, for example, various other transducers, MEMS mirrors, inkjet heads, or the like.

[0160] One or more elements of one embodiment described above may be combined with one or more elements of another embodiment.

[0161] As described above, according to the above-described transducer and method for manufacturing the transducer, it is possible to appropriately secure a gap between the vibration part having the piezoelectric element and the surrounding area. Various embodiments of the present disclosure can be defined as the following supplementary notes. (Supplementary Note 1, First embodiment, Second embodiment, Figs. 3A, 3B, 8, and 27) a support substrate 4 having a first cavity 5; A vibration device 6 supported by the support substrate 4; a cover 3 having a second cavity 3a and bonded to the vibration device 6 with an adhesive; Equipped with The vibration device 6 is a first frame portion 61 surrounding the first cavity 5 as viewed from the lid body 3 and having a first bonding surface 61a bonded to the lid body 3 by the adhesive 100; a vibration section 62 facing the first cavity 5 and having a piezoelectric element 10; having The vibration portion 62 is connected to the first frame portion 61 at a portion thereof. When viewed from the joining direction of the vibration device 6 and the lid 3, a portion of the vibration section 62 other than a connection portion between the vibration section 62 and the first frame section 61 is separated from the first frame section 61 by a slit 9 penetrating the vibration device 6 in the joining direction, The lid 3 has a second frame portion 30 that surrounds the second cavity 3a and includes a second bonding surface 306 that is bonded to the first bonding surface 61a by the adhesive 100, The first cavity 5 and the second cavity 3a are in communication with each other through the slit 9, A protrusion 8 that protrudes toward the second bonding surface 306 is formed on the first bonding surface 61a, A first step S1 is formed on an inner surface 615 of the first frame portion 61 facing the slit 9, the first step S1 being recessed from the first joint surface 61a toward the opposite side to the lid body 3. Transducer.

[0162] (Appendix 2, Second embodiment, Figs. 27 and 28) A second step S3 recessed toward the opposite side to the vibration device 6 is formed on inner surfaces 301a, 302a, 303a, and 304a of the second bonding surface 306 facing the second cavity 3a. 2. The transducer of claim 1.

[0163] (Appendix 3, First to Third Embodiments, Figs. 3A, 3B, 27, and 35) A plurality of recesses 306a are formed on the second bonding surface 306. 3. The transducer of claim 1 or 2.

[0164] (Appendix 4, First to Third Embodiments, Figs. 3A, 3B, 27, and 35) The vibration device 6 is an active layer 32 that is laminated on the support substrate 4 and contains silicon; a silicon oxide layer 33 laminated on the active layer 32 on the opposite side to the support substrate; having 4. A transducer according to any one of claims 1 to 3.

[0165] (Appendix 5, Third embodiment, Figs. 32 and 33) a support substrate 4 having a first cavity 5; A vibration device 6A supported by the support substrate 4; a cover 3A having a second cavity 3a and bonded to the vibration device 6A with an adhesive 100; Equipped with The vibration device 6A is a first frame portion 61 surrounding the first cavity 5 as viewed from the lid body 3A and having a first bonding surface 61a bonded to the lid body 3A by the adhesive 100; a vibration section 62 facing the first cavity 5 and having a piezoelectric element 10; having The vibration portion 62 is connected to the first frame portion 61 at a portion thereof. When viewed from the joining direction of the vibration device 6A and the lid body 3A, a portion of the vibration section 62 other than a connection portion between the vibration section 62 and the first frame section 61 is separated from the first frame section 61 by a slit 9 penetrating the vibration device 6A in the joining direction, The lid body 3A has a second frame portion 30 that surrounds the second cavity 3a and includes a second bonding surface 306 that is bonded to the first bonding surface 61a by the adhesive 100, The first cavity 5 and the second cavity 3a are in communication with each other through the slit 9, A protrusion 8 that protrudes toward the second bonding surface 306 is formed on the first bonding surface 61a, The second bonding surface 306 has inner surfaces 301a, 302a, 303a, and 304a facing the second cavity 3a, each of which has a recess S3 facing away from the vibration device 6A. Transducer.

[0166] (Appendix 6, Fourth embodiment, Figs. 34 and 35) a support substrate 4 having a first cavity 5; A vibration device 6A supported by the support substrate; a cover 3B having a second cavity 3a and bonded to the vibration device 6A with an adhesive 100; Equipped with The vibration device 6A is a first frame portion 61 surrounding the first cavity 5 as viewed from the lid body 3B and having a first bonding surface 61a bonded to the lid body 3B with the adhesive 100; a vibration section 62 facing the first cavity 5 and having a piezoelectric element 10; having The vibration portion 62 is connected to the first frame portion 61 at a portion thereof. When viewed from the joining direction of the vibration device 6A and the lid body 3B, a portion of the vibration section 62 other than a connection portion between the vibration section 62 and the first frame section 61 is separated from the first frame section 61 by a slit 9 penetrating the vibration device 6A in the joining direction, The lid body 3B has a second frame portion 30 that surrounds the second cavity 3a and includes a second bonding surface 306 that is bonded to the first bonding surface 61a by the adhesive 100, The first cavity 5 and the second cavity 3a are in communication with each other through the slit 9, A protrusion 8 that protrudes toward the second bonding surface 306 is formed on the first bonding surface 61a, A transducer, wherein the size of the second cavity 3a is larger than the size of the first cavity 5 when viewed from the joining direction.

[0167] (Appendix 7, First embodiment, Figs. 10 to 23) A method for manufacturing a transducer including a support substrate 4 having a first cavity 5, a vibration device 6 laminated on the support substrate 4, and a lid body 3 having a second cavity 3a and bonded to the vibration device 6 with an adhesive, comprising: a laminate manufacturing process for forming a laminate 2A including a first substrate 401 to be the support substrate 4 and the vibration device 6; a lid manufacturing process for manufacturing the lid 3; a bonding step of bonding the lid body 3 to the vibration device 6; a cavity forming step of forming a first cavity 5 in a first cavity formation region 501 of the first substrate 401; Equipped with The laminate manufacturing process includes: forming an intermediate laminate 101 including a vibration film forming layer 7 laminated on the first substrate 401, a piezoelectric element 10 provided above the first cavity formation region 501 of the vibration film forming layer 7, and an insulating film 20 covering the piezoelectric element 10 and the vibration film forming layer 7; forming a groove portion 911 from the insulating film 20 side along an outer periphery 501a of the first cavity formation region 501 in the intermediate laminate 101 except for a part of the outer periphery 501a; forming a protrusion 8 on the insulating film 20 outside the first cavity formation region 501; a step of forming a through hole 912 penetrating the intermediate laminate 101 in a part of a bottom surface 911a of the groove portion 911, thereby separating the intermediate laminate 101 into a vibration portion 62 including the piezoelectric element 10 and a frame portion 61 connected in part to the vibration portion 62 and surrounding the vibration portion 62, thereby obtaining the vibration device 6; having The lid manufacturing step includes a step of obtaining a lid 3 by forming a second cavity 3 a in a second substrate 70 to be the lid 3, the second cavity 3 a being in communication with the first cavity 5 through the groove 911 and the through hole 912, In the bonding step, the adhesive 100 is applied to a bonding surface 306 of the lid 3 with the vibration device 6, and the lid 3 is bonded to a surface of the vibration device 6 on which the protrusion 8 is formed, thereby bonding the lid 3 and the vibration device 6 together; In the cavity forming step, the first cavity 5 is formed in the first substrate 401, thereby obtaining a support substrate 4 in which the first cavity 5 is formed. A method for manufacturing a transducer.

[0168] (Appendix 8, First embodiment, FIG. 10) The vibration membrane forming layer 7 is an active layer 32 including silicon laminated on the support substrate 4; a silicon oxide layer 33 formed in the active layer 32 opposite the support substrate 4; having A method for manufacturing the transducer described in Appendix 7. [Explanation of symbols]

[0169] 1, 1A, 1B, 1C, 1D...Sound wave generating device (transducer) 2,2B…Board assembly 2A: PCB assembly work in progress 3,3A,3B…Lid body 3a...Cavity (2nd cavity) 4…Support substrate 5…Cavity (first cavity) 5a...Opening 6, 6A, 6C…Vibration device 7…Vibration membrane forming layer 7a...Vibration membrane 8…Convex part 8a…Core section 9…Slit 9a…Part 1 9b…Second part 9c…3rd part 10...Piezoelectric element 11...Lower electrode 12...Piezoelectric film 13…Top electrode 14A…First hydrogen barrier film 14B…Second hydrogen barrier film 15...Interlayer insulating film 16...Perseveration membrane 16a…Upper pad opening 16b…Lower pad opening 17…Upper wiring 17a…Upper pad 17b...1st wiring section 17c…Second wiring section 18…Lower wiring 18a…Lower pad section 18b...1st wiring section 18c…Second wiring section 19a…Contact hole 19b...Contact hole 20...Insulating film 30a...Groove 31...Silicon oxide film 32...Silicon substrate 33...Oxide film (silicon oxide layer) 34…Silicon layer 34a...hole formation area 35...Silicon oxide film 41…Part 1 42…Second part 43...Third part 44...4th part 61…First frame section 62...Cantilever (vibration part) 70...Substrate (second substrate) 71...Silicon substrate 72…First oxide film 72a…Aperture 72b…Aperture 72c…Aperture 73a…Aperture 73...Second oxide film 73b…Aperture 73c…Aperture 73d...Through hole 75...Through hole 81...Peeling layer 82…Support board 83...Resist film 91…Upper slit 92…Lower slit 100…Glue 101... Intermediate laminate 301…Part 1 301a…Inside 301b…Inside 301c…Inside 301d…Inside 302…Second part 302a…Inside 303...Third part 303a…Inside 304…4th part 304a…Inside 305a...Open part 305b...Open part 306...joint surface 306a...Groove 306a1…First groove part 306a2…Second groove part 308…Cavity formation area 308a...Outer edge 401...Substrate (first substrate) 411…Inside 421…Inside 431…Inside 441…Inner 501: Cavity formation region (first cavity formation region) 501a...Outer edge 611...Part 1 611A…1st A part 611B…Part 1B 612…Second part 613...Third part 614...4th part 61a... Joint surface 621... First edge 622... Second edge 623... Third edge 624... Fourth edge 611a... Inner surface 612a... Inner surface 613a... Inner surface 614a... Inner surface 615... Inner surface 721a... Island region 721b... Island region 721c... Island region 731a... Island region 731b... Island region 731c... Island region 911... Groove part 911a... Bottom surface 912... Through hole A... Region S1... Step S2... Step S3... Step d1... Retraction amount d2... Retraction amount d3... Retraction amount d4... Retraction amount H... Hole part H1... Hole part R... Resist film W1... Width W2... Width

Claims

1. a support substrate having a first cavity; a vibration device supported by the support substrate; a cover having a second cavity and bonded to the vibration device by an adhesive; Equipped with The vibration device includes: a first frame portion surrounding the first cavity when viewed from the lid body and having a first bonding surface bonded to the lid body by the adhesive; a vibration section facing the first cavity and having a piezoelectric element; having The vibration portion has a portion connected to the first frame portion, When viewed from a joining direction of the vibration device and the lid, a portion of the vibration part other than a connection part between the vibration part and the first frame part is separated from the first frame part by a slit penetrating the vibration device in the joining direction, the lid body has a second frame portion surrounding the second cavity and including a second bonding surface bonded to the first bonding surface by the adhesive, the first cavity and the second cavity are in communication with each other through the slit, a convex portion that is convex toward the second bonding surface is formed on the first bonding surface, A first step is formed on an inner surface of the first frame portion facing the slit, the first step being recessed from the first joint surface toward the opposite side to the lid body. Transducer.

2. A second step recessed in a direction away from the vibration device is formed on an inner surface of the second joint surface facing the second cavity. The transducer of claim 1 .

3. A plurality of recesses are formed on the second bonding surface. The transducer of claim 1 .

4. The vibration device includes: an active layer that is laminated on the support substrate and contains silicon; a silicon oxide layer stacked on the active layer opposite the support substrate; having A transducer according to any one of claims 1 to 3.

5. a support substrate having a first cavity; a vibration device supported by the support substrate; a cover having a second cavity and bonded to the vibration device by an adhesive; Equipped with The vibration device includes: a first frame portion surrounding the first cavity when viewed from the lid body and having a first bonding surface bonded to the lid body by the adhesive; a vibration section facing the first cavity and having a piezoelectric element; having The vibration portion has a portion connected to the first frame portion, When viewed from a joining direction of the vibration device and the lid, a portion of the vibration part other than a connection part between the vibration part and the first frame part is separated from the first frame part by a slit penetrating the vibration device in the joining direction, the lid body has a second frame portion surrounding the second cavity and including a second bonding surface bonded to the first bonding surface by the adhesive, the first cavity and the second cavity are in communication with each other through the slit, a convex portion that is convex toward the second bonding surface is formed on the first bonding surface, A step is formed on an inner surface of the second joint surface facing the second cavity, the step being recessed in a direction away from the vibration device. Transducer.

6. a support substrate having a first cavity; a vibration device supported by the support substrate; a cover having a second cavity and bonded to the vibration device by an adhesive; Equipped with The vibration device includes: a first frame portion surrounding the first cavity when viewed from the lid body and having a first bonding surface bonded to the lid body by the adhesive; a vibration section facing the first cavity and having a piezoelectric element; having The vibration portion has a portion connected to the first frame portion, When viewed from a joining direction of the vibration device and the lid, a portion of the vibration part other than a connection part between the vibration part and the first frame part is separated from the first frame part by a slit penetrating the vibration device in the joining direction, the lid body has a second frame portion surrounding the second cavity and including a second bonding surface bonded to the first bonding surface by the adhesive, the first cavity and the second cavity are in communication with each other through the slit, a convex portion that is convex toward the second bonding surface is formed on the first bonding surface, A transducer, wherein the size of the second cavity is larger than the size of the first cavity when viewed from the joining direction.

7. A method for manufacturing a transducer including a support substrate having a first cavity, a vibration device stacked on the support substrate, and a lid having a second cavity and bonded to the vibration device with an adhesive, comprising: a laminate manufacturing process for forming a laminate of a first substrate to be the support substrate and the vibration device; a lid manufacturing process for manufacturing the lid; a joining step of joining the lid to the vibration device; a cavity forming step of forming a first cavity in a region in the first substrate where a first cavity is to be formed; Equipped with The laminate manufacturing process includes: forming an intermediate laminate including a vibration film forming layer laminated on the first substrate, a piezoelectric element provided above the region of the vibration film forming layer where the first cavity is to be formed, and an insulating film covering the piezoelectric element and the vibration film forming layer; forming a groove portion from the insulating film side along an outer periphery of the first cavity formation region in the intermediate laminate other than a part of the outer periphery; forming a protrusion on the insulating film outside a region where the first cavity is to be formed; a step of obtaining the vibration device by forming a through hole penetrating the intermediate laminate in a portion of a bottom surface of the groove portion, thereby separating the intermediate laminate into a vibration portion including the piezoelectric element and a frame portion connected in part to the vibration portion and surrounding the vibration portion; having the lid manufacturing step includes a step of obtaining a lid by forming a second cavity in a second substrate to be the lid, the second cavity being in communication with the first cavity through the groove portion and the through hole; In the bonding step, an adhesive is applied to a bonding surface of the lid body with respect to the vibration device, and the lid body is bonded to a surface of the vibration device on which the convex portion is formed, thereby bonding the lid body to the vibration device; In the cavity forming step, the first cavity is formed in the first substrate to obtain a support substrate in which the first cavity is formed. A method for manufacturing a transducer.

8. The vibration membrane forming layer is an active layer including silicon laminated on the support substrate; a silicon oxide layer formed in the active layer opposite the support substrate; having A method for manufacturing a transducer according to claim 7.

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