piezoelectric device

Abstract

A through groove (180) which penetrates in the up-down direction is provided in the diaphragm portion (Mb). The width of the through groove (180) in the single-crystal piezoelectric layer (130) becomes narrower as it goes downward. In the single-crystal piezoelectric layer (130) and the reinforcing layer (160), the maximum width of the through groove (180) in the layer on the lower side is smaller than the minimum width of the through groove (180) in the layer on the upper side.

Description

TECHNICAL FIELD

[0001] The present application relates to a piezoelectric device. BACKGROUND

[0002] As a document disclosing a structure of a piezoelectric device, there is International Publication No. 2017 / 218299 (Patent Literature 1). The piezoelectric device described in Patent Literature 1 has a substrate and a diaphragm portion. The substrate has an opening portion that penetrates the substrate. The diaphragm portion is formed of at least one elastic layer, and at least one piezoelectric layer sandwiched between an upper electrode layer and a lower electrode layer. The diaphragm portion is mounted to the substrate above the opening portion. In the diaphragm portion near an end portion of the opening portion, a through groove is formed by etching.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: International Publication No. 2017 / 218299 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] When the diaphragm portion is vibrated up and down, in a case where the viscous resistance between the diaphragm portion and the fluid passing through the through groove is large, the excitation efficiency of the piezoelectric device decreases.

[0008] The present application has been made in view of the above-described problems, and an object thereof is to provide a piezoelectric device with high excitation efficiency.

[0009] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0010] The piezoelectric device according to the present application has a base portion and a laminated portion. The base portion includes one main surface and another main surface on the side opposite to the one main surface, and has an opening portion that penetrates from the one main surface to the another main surface. The laminated portion is laminated on the one main surface side of the base portion, and covers the opening portion from above. The laminated portion includes, at least above the opening portion, a single-crystal piezoelectric body layer, an upper electrode layer disposed on the upper side of the single-crystal piezoelectric body layer, a lower electrode layer opposing at least a part of the upper electrode layer through the single-crystal piezoelectric body layer, a reinforcing layer sandwiching the upper electrode layer or the lower electrode layer between the single-crystal piezoelectric body layer, and has a diaphragm portion as a portion covering the opening portion. A through groove that penetrates in the up-and-down direction is provided in the diaphragm portion. The width of the through groove in the single-crystal piezoelectric body layer narrows downward. In the single-crystal piezoelectric body layer and the reinforcing layer, the maximum width of the through groove in the layer on the lower side is smaller than the minimum width of the through groove in the layer on the upper side.

[0011] EFFECTS OF THE INVENTION

[0012] According to the present application, it is possible to improve the excitation efficiency of the piezoelectric device. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a plan view of a piezoelectric device to which Embodiment 1 of the present application relates.

[0014] Figure 2 is a sectional view of the piezoelectric device of Figure 1 observed from the arrow direction of line II-II.

[0015] Figure 3 is a sectional view showing a state in which a close contact layer is provided to a lower surface of a single-crystal piezoelectric layer in a manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0016] Figure 4 is a sectional view showing a state in which a lower electrode layer is provided to respective lower surfaces of the close contact layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0017] Figure 5 is a sectional view showing a state in which a reinforcing layer is provided to respective lower surfaces of the lower electrode layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0018] Figure 6 is a sectional view showing a state in which a lower surface of the reinforcing layer is flattened in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0019] Figure 7 is a sectional view showing a state in which a base portion is to be joined to Figure 6 a plurality of layers shown in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0020] Figure 8 is a sectional view showing a state after the base portion is joined to a lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0021] Figure 9 is a sectional view showing a state after an upper surface of the single-crystal piezoelectric layer is shaved in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0022] Figure 10 is a sectional view showing a state in which an upper electrode layer is provided to an upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0023] Figure 11 is a sectional view showing a state in which a hole portion is provided to the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device to which Embodiment 1 of the present application relates.

[0024] Figure 12 is a sectional view showing a state in which a through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application.

[0025] Figure 13 is a sectional view showing a state in which a through groove is provided in a manner reaching the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application.

[0026] Figure 14 is a sectional view showing a state in which the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application.

[0027] Figure 15 is a sectional view showing the structure of the piezoelectric device according to the first modification of Embodiment 1 of the present application.

[0028] Figure 16 is a sectional view showing the structure of the piezoelectric device according to the second modification of Embodiment 1 of the present application.

[0029] Figure 17 is a schematic view of the longitudinal sectional shape of the through groove of the diaphragm portion in the piezoelectric device according to the second modification of Embodiment 1 of the present application.

[0030] Figure 18 is a sectional view showing the structure of the piezoelectric device according to the third modification of Embodiment 1 of the present application.

[0031] Figure 19 is a schematic view of the longitudinal sectional shape of the through groove of the diaphragm portion in the piezoelectric device according to the third modification of Embodiment 1 of the present application.

[0032] Figure 20 is a sectional view of the piezoelectric device according to Embodiment 2 of the present application.

[0033] Figure 21 is a sectional view showing a state in which reinforcing layers are provided on the respective lower surfaces of the lower electrode layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0034] Figure 22 is a sectional view showing a state in which the lower surface of the reinforcing layer is flattened in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0035] Figure 23 is a sectional view showing a state in which the base portion is to be joined tothe plurality of layers shown in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. Figure 22

[0036] Figure 24is a sectional view showing a state after the base portion is joined to the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0037] Figure 25 is a sectional view showing a state after the upper surface of the single-crystal piezoelectric layer is shaved in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0038] Figure 26 is a sectional view showing a state where the upper electrode layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0039] Figure 27 is a sectional view showing a state where the hole portion is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0040] Figure 28 is a sectional view showing a state where the through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0041] Figure 29 is a sectional view showing a state where the through groove is provided so as to reach the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0042] Figure 30 is a sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application.

[0043] Figure 31 is a sectional view showing the structure of the piezoelectric device according to the 1st modification of Embodiment 2 of the present application.

[0044] Figure 32 is a sectional view showing the structure of the piezoelectric device according to the 2nd modification of Embodiment 2 of the present application.

[0045] Figure 33 is a sectional view showing the structure of the piezoelectric device according to the 3rd modification of Embodiment 2 of the present application.

[0046] Figure 34 is a sectional view of the piezoelectric device according to Embodiment 3 of the present application.

[0047] Figure 35 is a sectional view showing a state where the plurality of layers shown in Figure 6 are joined to the base portion in which the additional reinforcing layer is laminated in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0048] Figure 36is a sectional view showing a state after the additional reinforcing layer is joined to the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0049] Figure 37 is a sectional view showing a state after the upper surface of the single-crystal piezoelectric layer is shaved in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0050] Figure 38 is a sectional view showing a state where the upper electrode layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0051] Figure 39 is a sectional view showing a state where the hole portion is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0052] Figure 40 is a sectional view showing a state where the through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0053] Figure 41 is a sectional view showing a state where the through groove is provided so as to reach the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0054] Figure 42 is a sectional view showing a state where the through groove is provided so as to reach the lower surface of the additional reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0055] Figure 43 is a sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0056] Figure 44 is a sectional view showing the structure of the piezoelectric device according to the first modification of Embodiment 3 of the present application.

[0057] Figure 45 is a sectional view showing the structure of the piezoelectric device according to the second modification of Embodiment 3 of the present application.

[0058] Figure 46 is a sectional view showing the structure of the piezoelectric device according to the third modification of Embodiment 3 of the present application.

[0059] Figure 47 is a sectional view of the piezoelectric device according to Embodiment 4 of the present application.

[0060] Figure 48is a sectional view showing a state in which a reinforcing layer is provided on each of the upper surfaces of the upper electrode layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application.

[0061] Figure 49 is a sectional view showing a state in which the upper surface of the reinforcing layer is flattened in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application.

[0062] Figure 50 is a sectional view showing a state in which a hole portion is provided in each of the single-crystal piezoelectric layer and the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application.

[0063] Figure 51 is a sectional view showing a state in which a through groove is provided in each of the reinforcing layer and the upper electrode layer in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application.

[0064] Figure 52 is a sectional view showing a state in which a through groove is provided in such a manner as to reach the lower surface of the lower electrode layer in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application.

[0065] Figure 53 is a sectional view showing a state in which an opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application.

[0066] Figure 54 is a sectional view showing a structure of the piezoelectric device according to the 1st modification of Embodiment 4 of the present application.

[0067] Figure 55 is a sectional view showing a structure of the piezoelectric device according to the 2nd modification of Embodiment 4 of the present application.

[0068] Figure 56 is a sectional view showing a structure of the piezoelectric device according to the 3rd modification of Embodiment 4 of the present application.

[0069] Figure 57 is a sectional view of the piezoelectric device according to Embodiment 5 of the present application.

[0070] Figure 58 is a sectional view showing a state in which the single-crystal piezoelectric layer is to be bonded to the SOI substrate in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0071] Figure 59 is a sectional view showing a state after the upper surface of the single-crystal piezoelectric layer is shaved in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0072] Figure 60is a sectional view showing a state where the upper electrode layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0073] Figure 61 is a sectional view showing a state where the hole portion is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0074] Figure 62 is a sectional view showing a state where the through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0075] Figure 63 is a sectional view showing a state where the through groove is provided in such a manner as to reach the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0076] Figure 64 is a sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present application.

[0077] Figure 65 is a sectional view of the piezoelectric device according to Embodiment 6 of the present application.

[0078] Figure 66 is a sectional view showing a state where the reinforcing layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present application.

[0079] Figure 67 is a sectional view showing a state where the hole portion is provided in the single-crystal piezoelectric layer and the reinforcing layer, respectively, in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present application.

[0080] Figure 68 is a sectional view showing a state where the through groove is provided in the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present application.

[0081] Figure 69 is a sectional view showing a state where the through groove is provided in such a manner as to reach the lower surface of the lower electrode layer in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present application.

[0082] Figure 70 is a sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present application.

[0083] Figure 71 is a sectional view of the piezoelectric device according to Embodiment 7 of the present application.

[0084] Figure 72is a cross-sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 7 of the present application.

[0085] Figure 73 is a cross-sectional view showing a state where the through groove is provided so as to reach the upper surface of the lower electrode layer from the opening portion side in the manufacturing method of the piezoelectric device according to Embodiment 7 of the present application.

[0086] Figure 74 is a schematic view of a longitudinal cross-sectional shape of the through groove of the diaphragm portion in the piezoelectric device according to Embodiment 7 of the present application. DETAILED DESCRIPTION

[0087] Hereinafter, the piezoelectric device according to each embodiment of the present application will be described with reference to the drawings. In the description of the following embodiments, the same reference numerals are assigned to the same or corresponding portions in the drawings, and the description thereof will not be repeated.

[0088] (Embodiment 1)

[0089] Figure 1 is a plan view of the piezoelectric device according to Embodiment 1 of the present application. Figure 2 is a cross-sectional view of the piezoelectric device according to Embodiment 1 of the present application, as viewed from the II-II line arrow direction. Figure 1 In Figure 1 , the structure of the inside of the piezoelectric device is indicated by a broken line. As shown in Figure 1 and Figure 2 , the piezoelectric device 100 according to Embodiment 1 of the present application includes a base portion 110 and a laminated portion 120.

[0090] The base portion 110 includes one main surface 111 and another main surface 112 located on the side opposite to the one main surface 111. The base portion 110 has an opening portion 113 that penetrates from the one main surface 111 to the another main surface 112. The opening portion 113 is covered from above by the laminated portion 120 laminated on the one main surface 111 side of the base portion 110.

[0091] In the present embodiment, the base portion 110 is composed of a bulk base portion 110a and a surface layer base portion 110b that covers the upper surface of the bulk base portion 110a. In the present embodiment, the bulk base portion 110a is composed of Si, and the surface layer base portion 110b is composed of SiO2. However, the material constituting the bulk base portion 110a is not limited to Si, and the material constituting the surface layer base portion 110b is not limited to SiO2.

[0092] The laminated portion 120 includes at least a single-crystal piezoelectric body layer 130, an upper electrode layer 140, a lower electrode layer 150, and a reinforcing layer 160 above the opening portion 113.

[0093] The laminated portion 120 has a diaphragm portion Mb that is a portion covering the opening portion 113. The diaphragm portion Mb is a portion of the laminated portion 120 that is located inside the opening end portion of the opening portion 113, as viewed in a direction orthogonal to one major surface 111. A through groove 180 that penetrates the diaphragm portion Mb in the up-down direction is provided in the diaphragm portion Mb.

[0094] The single-crystal piezoelectric layer 130 is located on the upper side than the base portion 110. A portion of the single-crystal piezoelectric layer 130 is located above the opening portion 113. The upper surface and the lower surface of the single-crystal piezoelectric layer 130 are each flat.

[0095] The single-crystal piezoelectric layer 130 has a hole portion 131. The hole portion 131 penetrates the single-crystal piezoelectric layer 130 in the up-down direction. In the present embodiment, the hole portion 131 is located above the one major surface 111 of the base portion 110, and is not located above the opening portion 113.

[0096] The single-crystal piezoelectric layer 130 is composed of lithium tantalate or lithium niobate. The polarization state is the same with respect to the single-crystal piezoelectric layer 130 composed of lithium tantalate or lithium niobate.

[0097] The upper electrode layer 140 is disposed on the upper side of the single-crystal piezoelectric layer 130. A portion of the upper electrode layer 140 is located above the opening portion 113. In the present embodiment, the upper electrode layer 140 is disposed on the upper side of a portion of the single-crystal piezoelectric layer 130. The upper electrode layer 140 is composed of, for example, a metal such as Al or Pt. In addition, a close contact layer composed of Ti or the like can be disposed between the upper electrode layer 140 and the single-crystal piezoelectric layer 130.

[0098] The lower electrode layer 150 opposes at least a portion of the upper electrode layer 140 with the single-crystal piezoelectric layer 130 interposed therebetween. In the present embodiment, a portion of the lower electrode layer 150 opposes a portion of the upper electrode layer 140 with the single-crystal piezoelectric layer 130 interposed therebetween. A portion of the lower electrode layer 150 is located above the opening portion 113.

[0099] Another portion of the lower electrode layer 150 is located below the hole portion 131 formed in the single-crystal piezoelectric layer 130. In the present embodiment, the other portion of the lower electrode layer 150 is connected to the single-crystal piezoelectric layer 130 via a close contact layer 155. The close contact layer 155 covers the hole portion 131 of the single-crystal piezoelectric layer 130 from below. In addition, it is not necessarily required to provide the close contact layer 155. In the case where the close contact layer 155 is not provided, the other portion of the lower electrode layer 150 directly covers the hole portion 131 from below.

[0100] The lower electrode layer 150 is composed of, for example, a metal such as Al or Pt. With respect to the material of the close contact layer 155, there is no particular limitation as long as it is a material having conductivity and close contact properties. The close contact layer 155 is composed of, for example, Ti, Cr, Ni, or NiCr.

[0101] The reinforcing layer 160 is sandwiched between the single-crystal piezoelectric layer 130 and the upper electrode layer 140 or the lower electrode layer 150. In the present embodiment, the reinforcing layer 160 is disposed at a position lower than the single-crystal piezoelectric layer 130. The reinforcing layer 160 is sandwiched between the lower electrode layer 150 and the single-crystal piezoelectric layer 130. The reinforcing layer 160 is in contact with the lower surface of the lower electrode layer 150 and the portion of the lower surface of the single-crystal piezoelectric layer 130 which is not covered by the lower electrode layer 150, respectively.

[0102] A portion of the reinforcing layer 160 is positioned above the opening portion 113. A portion of the reinforcing layer 160 covers the opening portion 113. The reinforcing layer 160 which does not cover the opening portion 113 is directly connected to the base portion 110. Alternatively, the reinforcing layer 160 which does not cover the opening portion 113 can not be directly connected to the base portion 110. The reinforcing layer 160 which does not cover the opening portion 113 can be connected to the base portion 110 via a metal layer.

[0103] In the present embodiment, the reinforcing layer 160 is composed of Si3N4. Alternatively, the material of the reinforcing layer 160 is not limited to Si3N4, but can be another insulator. For example, the reinforcing layer 160 can be composed of an organic material having electrical insulation and thermal insulation.

[0104] As shown in Figs. 1 and 2, the piezoelectric device 100 further includes a first lead wire 171 and a second lead wire 172. The first lead wire 171 is laminated on the upper side of a portion of the upper electrode layer 140. The second lead wire 172 is laminated on the upper side of each of a portion of the single-crystal piezoelectric layer 130 and the airtight layer 155. The second lead wire 172 is laminated on the upper side of the lower electrode layer 150 via the airtight layer 155 inside the hole portion 131. Figure 1 Figure 2 As shown in Figs. 1 and 2, the piezoelectric device 100 further includes a first lead wire 171 and a second lead wire 172. The first lead wire 171 is laminated on the upper side of a portion of the upper electrode layer 140. The second lead wire 172 is laminated on the upper side of each of a portion of the single-crystal piezoelectric layer 130 and the airtight layer 155. The second lead wire 172 is laminated on the upper side of the lower electrode layer 150 via the airtight layer 155 inside the hole portion 131.

[0105] Thus, the laminated portion 120 includes the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, and the reinforcing layer 160 at least above the opening portion 113.

[0106] In the present embodiment, the shape of the opening portion 113 is rectangular when viewed from the direction orthogonal to the one main surface 111. However, the shape of the opening portion 113 is not limited to a rectangle when viewed from the direction orthogonal to the one main surface 111, but can be a polygon other than a rectangle or a circle.

[0107] According to the above-described structure, by applying a voltage between the upper electrode layer 140 and the lower electrode layer 150, the diaphragm portion Mb is bent and vibrates up and down in accordance with the expansion and contraction of the single-crystal piezoelectric layer 130.

[0108] ​As described above, the through groove 180 that penetrates the diaphragm portion Mb in the up-and-down direction is provided in the diaphragm portion Mb. The width of the through groove 180 is narrower in the respective layers of the single-crystal piezoelectric layer 130 and the reinforcing layer 160 as it goes downward.

[0109] In the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the maximum width of the through groove 180 in the layer on the lower side is smaller than the minimum width of the through groove 180 in the layer on the upper side. In the present embodiment, the reinforcing layer 160 is the layer on the lower side, and the single-crystal piezoelectric layer 130 is the layer on the upper side. The maximum width of the through groove 180 in the reinforcing layer 160 is smaller than the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130.

[0110] Specifically, the single-crystal piezoelectric layer 130 has an end surface 138 that is continuous with the through groove 180. The reinforcing layer 160 has an end surface 168 that is continuous with the through groove 180. The lower electrode layer 150 that is sandwiched between the single-crystal piezoelectric layer 130 and the reinforcing layer 160 has an end surface 158.

[0111] In the present embodiment, the end surface 138 is an upper side end surface, the end surface 168 is a lower side end surface, and the end surface 158 is an intermediate end surface. The inclination angle of the end surface 138 as the upper side end surface is smaller than the inclination angle of the end surface 168 as the lower side end surface. That is, the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130 is the width of the through groove 180 at the position of the lower end of the end surface 138 of the single-crystal piezoelectric layer 130. The maximum width of the through groove 180 in the reinforcing layer 160 is the width of the through groove 180 at the position of the upper end of the end surface 168 of the reinforcing layer 160.

[0112] The end surface 158 as the intermediate end surface is located on the extension of the end surface 168 as the lower side end surface, and is continuous with the end surface 168. A step is formed between the end surface 138 as the upper side end surface and the end surface 158 as the intermediate end surface. The lower end of the end surface 138 as the upper side end surface is located on the upper surface of the lower electrode layer 150. A part of the upper surface of the lower electrode layer 150 that is adjacent to the through groove 180 is exposed.

[0113] As Figure 2As shown, the width of the through groove 180 narrows from its upper end to its lower end. Alternatively, the width of the through groove 180 may narrow in a stepped manner from its upper end to its lower end. That is, it may include a portion where the width of the through groove 180 remains constant from its upper end to its lower end. In this embodiment, the width of the through groove 180 is approximately the same from the upper end to the lower end of the upper electrode layer 140 in the vertical direction. The width of the through groove 180 may also be approximately the same from the upper end to the lower end of the lower electrode layer 150 in the vertical direction. In this case, the inclination angle of the end face 158 of the lower electrode layer 150 is 90°.

[0114] The through groove 180 is narrowest at its end on the side of the opening 113. That is, the through groove 180 is narrowest at the lower end of the end face 168 of the vertical reinforcing layer 160.

[0115] The manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention will be described below.

[0116] Figure 3 This is a cross-sectional view showing a state in which a close-fitting layer is provided on the lower surface of a single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. The thickness of the single-crystal piezoelectric layer 130 during formation is thicker than the thickness of the single-crystal piezoelectric layer 130 ultimately included in the piezoelectric device 100 according to this embodiment.

[0117] like Figure 3 As shown, a close bonding layer 155 is formed on the lower surface of the single crystal piezoelectric layer 130 by means of lift-off, plating or etching.

[0118] Figure 4 This is a cross-sectional view showing a state in which a lower electrode layer is provided on the lower surface of both the close-fitting layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 4 As shown, the lower electrode layer 150 is provided on the entire surface of the lower surface of the bonding layer 155 and a portion of the lower surface of the single crystal piezoelectric layer 130 by means of peeling, plating or etching.

[0119] Figure 5 This is a cross-sectional view showing a state in which a reinforcement layer is provided on the lower surface of both the lower electrode layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 5As shown, reinforcement layers 160 are formed on the lower surfaces of the lower electrode layer 150 and the single crystal piezoelectric layer 130 by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0120] Figure 6 This is a cross-sectional view showing the state after the lower surface of the reinforcing layer is flattened in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 6 As shown, the lower surface of the reinforcing layer 160 is flattened by chemical mechanical polishing (CMP).

[0121] Figure 7 This illustrates that in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention, the base is to be bonded to... Figure 6 A cross-sectional view showing the state of multiple layers. Figure 8 This is a cross-sectional view showing the state after the base is bonded to the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention.

[0122] like Figure 7 and Figure 8 As shown, the base 110 is composed of a main body base 110a and a surface base 110b covering the upper surface of the main body base 110a. The surface base 110b is formed by thermal oxidation of the upper surface of the main body base 110a. The substrate 110, which is the base without the opening 113, is bonded to the lower surface of the reinforcement layer 160 by surface activation bonding or atomic diffusion bonding, etc.

[0123] Figure 9 This is a cross-sectional view showing the state after the upper surface of the single-crystal piezoelectric layer has been removed in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present invention. Figure 9 As shown, the upper surface of the single-crystal piezoelectric layer 130 is removed by CMP or similar methods to achieve the desired thickness. Alternatively, a release layer can be formed on the upper surface side of the single-crystal piezoelectric layer 130 beforehand by ion implantation. In this case, the release layer is removed before the upper surface of the single-crystal piezoelectric layer 130 is removed by cutting or CMP, thereby facilitating the adjustment of the thickness of the single-crystal piezoelectric layer 130. The thickness of the single-crystal piezoelectric layer 130 is adjusted to obtain the desired excitation of the single-crystal piezoelectric layer 130 caused by the application of voltage.

[0124] Figure 10is a sectional view showing a state in which the upper electrode layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application. As shown in Figure 10 the upper electrode layer 140 is provided on a part of the upper surface of the single-crystal piezoelectric layer 130 by a lift-off method, a plating method, or an etching method, or the like.

[0125] Figure 11 is a sectional view showing a state in which the hole portion is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application. As shown in Figure 11 the hole portion 131 is formed by etching a part of the single-crystal piezoelectric layer 130.

[0126] Figure 12 is a sectional view showing a state in which the through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application. As shown in Figure 12 the through groove 180 is formed in the single-crystal piezoelectric layer 130 by etching the single-crystal piezoelectric layer 130. Thus, the end surface 138 which is in contact with the through groove 180 is formed in the single-crystal piezoelectric layer 130.

[0127] Figure 13 is a sectional view showing a state in which the through groove is provided so as to reach the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application. As shown in Figure 13 the through groove 180 is formed in the lower electrode layer 150 and the reinforcing layer 160 by etching the lower electrode layer 150 and the reinforcing layer 160, respectively. Thus, the end surface 158 which is in contact with the through groove 180 is formed in the lower electrode layer 150. The end surface 168 which is in contact with the through groove 180 is formed in the reinforcing layer 160.

[0128] Figure 14 is a sectional view showing a state in which the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 1 of the present application. As shown in Figure 14 the opening portion 113 is formed in the base portion 110 by deep reactive ion etching or the like from the other main surface 112 side of the base portion 110. Thus, the diaphragm portion Mb is formed in the piezoelectric device 100 according to the present embodiment.

[0129] Finally, the first lead wire 171 and the second lead wire 172 are provided by a lift-off method, a plating method, or an etching method, or the like, respectively. By the above procedures, the piezoelectric device 100 according to Embodiment 1 of the present application shown in Figure 2 is manufactured.

[0130] As described above, in the piezoelectric device 100 according to Embodiment 1 of the present application, the width of the through groove 180 is narrower as it goes downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 160. In the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side.

[0131] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb vibrates up and down can be reduced, and thus the excitation efficiency of the piezoelectric device 100 can be improved.

[0132] In the present embodiment, the width of the through groove 180 in the portion where the single-crystal piezoelectric layer 130 is located can be made wide, and the width of the through groove 180 in the portion where the reinforcing layer 160 is located can be made narrow. As a result, the stress acting on the single-crystal piezoelectric layer 130 when the diaphragm portion Mb vibrates in bending can be alleviated, and thus the occurrence of the interlayer peeling between the single-crystal piezoelectric layer 130 and the upper electrode layer 140 and between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be suppressed.

[0133] Further, the width of the through groove 180 in the portion where the reinforcing layer 160 is located can be made narrow, and thus the reduction in the characteristics of the piezoelectric device 100 due to the width of the through groove 180 becoming too wide can be suppressed. For example, in the case where the piezoelectric device 100 is used as an acoustic device, the reduction in the acoustic impedance due to the width of the through groove 180 becoming too wide can be suppressed.

[0134] In the piezoelectric device 100 according to the present embodiment, the inclination angle of the end surface 138 of the single-crystal piezoelectric layer 130 as the upper side end surface is smaller than the inclination angle of the end surface 168 of the reinforcing layer 160 as the lower side end surface. Thus, the viscous resistance at the end surface 138 of the single-crystal piezoelectric layer 130 can be effectively reduced.

[0135] In the piezoelectric device 100 according to the present embodiment, the single-crystal piezoelectric layer 130 is composed of lithium tantalate or lithium niobate. Thus, the piezoelectric characteristics of the piezoelectric device 100 can be improved.

[0136] Hereinafter, a modified example of the piezoelectric device 100 according to Embodiment 1 of the present application will be described.

[0137] Figure 15 is a cross-sectional view showing the structure of the piezoelectric device according to the first modified example of Embodiment 1 of the present application. In Figure 15 , the same cross-sectional view as Figure 2 is shown. As Figure 15As shown in FIG. 1, in the piezoelectric device 100a related to the first modification of Embodiment 1 of the present application, the inclination angle of the end surface 168a of the reinforcing layer 160 as the lower side end surface is smaller than the inclination angle of the end surface 138a of the single-crystal piezoelectric layer 130 as the upper side end surface. The end surface 158a of the lower electrode layer 150 as the intermediate end surface is located on the extension plane of the end surface 168a as the lower side end surface, and is continuous with the end surface 168a. Thus, the viscous resistance at the end surface 168a of the reinforcing layer 160 can be effectively reduced.

[0138] Figure 16 FIG. 1 is a cross-sectional view showing the structure of a piezoelectric device related to the second modification of Embodiment 1 of the present application. In Figure 16 , the same cross-sectional view as Figure 2 is illustrated. As Figure 16 shown in FIG. 1, in the piezoelectric device 100b related to the second modification of Embodiment 1 of the present application, in the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the lower side end surface in the layer located on the lower side, which is in contact with the through groove 180, and the upper side end surface in the layer located on the upper side, which is in contact with the through groove 180, are continuous via the intermediate end surface in the upper electrode layer 140 or the lower electrode layer 150, which is in contact with the through groove 180.

[0139] In the present modification, the end surface 168 of the reinforcing layer 160 as the lower side end surface and the end surface 138b of the single-crystal piezoelectric layer 130 as the upper side end surface are continuous via the end surface 158 of the lower electrode layer 150 as the intermediate end surface.

[0140] As Figure 16 shown in FIG. 1, in the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the maximum width of the through groove 180 in the layer located on the upper side is du, the minimum width of the through groove 180 in the layer located on the upper side is dm1, and the minimum width of the through groove 180 in the layer located on the lower side is db. The inclination angle of the upper side end surface is smaller than the inclination angle of the lower side end surface. The relationship of du > dm1 > db is satisfied.

[0141] Figure 17 FIG. 1 is a cross-sectional view showing the structure of a piezoelectric device related to the second modification of Embodiment 1 of the present application. In Figure 17 As shown in FIG. 1, by making the inclination angle of the upper side end surface smaller than the inclination angle of the lower side end surface, the viscous resistance of the fluid F1 which is immersed into the through groove 180 from the upper side can be reduced.

[0142] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb is vibrated up and down can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 100b can be improved. Further, stress concentration between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be alleviated, and thus occurrence of interlayer peeling between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be suppressed.

[0143] Figure 18 is a cross-sectional view illustrating a structure of a piezoelectric device according to a third modification of Embodiment 1 of the present application. In Figure 18 , the same cross-sectional view as Figure 2 is illustrated. As shown in Figure 18 , in the piezoelectric device 100c according to the third modification of Embodiment 1 of the present application, the inclination angle of the end surface 168a of the reinforcing layer 160 as the lower side end surface is smaller than the inclination angle of the end surface 138c of the single-crystal piezoelectric layer 130 as the upper side end surface. Thus, the viscous resistance at the end surface 168a of the reinforcing layer 160 can be effectively reduced.

[0144] Further, the end surface 168a of the reinforcing layer 160 as the lower side end surface and the end surface 138c of the single-crystal piezoelectric layer 130 as the upper side end surface are continuous via the end surface 158a of the lower electrode layer 150 as the intermediate end surface.

[0145] As shown in Figure 18 , in the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the maximum width of the through groove 180 in the layer on the upper side is du, the minimum width of the through groove 180 in the layer on the upper side is dm2, and the minimum width of the through groove 180 in the layer on the lower side is db. The inclination angle of the lower side end surface is smaller than the inclination angle of the upper side end surface. The relationship of du > dm2 > db is satisfied.

[0146] Figure 19 is a schematic view of the longitudinal cross-sectional shape of the through groove of the diaphragm portion in the piezoelectric device according to the third modification of Embodiment 1 of the present application. As shown in Figure 19 , by making the inclination angle of the lower side end surface smaller than the inclination angle of the upper side end surface, the viscous resistance to the fluid F2 immersed in the through groove 180 from the lower side can be reduced.

[0147] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb is vibrated up and down can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 100c can be improved. Further, stress concentration between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be alleviated, and thus occurrence of interlayer peeling between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be suppressed.

[0148] As shown in Figure 17 and Figure 19As shown, in a case where the maximum width du of the through groove 180 in the layer on the upper side and the minimum width db of the through groove 180 in the layer on the lower side are respectively fixed at certain dimensions, the relationship of dm1 < dm2 is satisfied. That is, by adjusting the inclination angle of the upper side end surface and the inclination angle of the lower side end surface, it is possible to control the profile of the longitudinal section of the through groove 180 while maintaining the dimensions of both ends in the vertical direction of the through groove 180. From the viewpoint of constraints on processing and suppression of the immersion of foreign matter into the through groove 180, the degree of freedom of the dimensions of both ends in the vertical direction of the through groove 180 is small. Therefore, by adjusting the inclination angle of the upper side end surface and the inclination angle of the lower side end surface respectively while maintaining the dimensions of both ends in the vertical direction of the through groove 180, it is possible to suppress the immersion of foreign matter into the through groove 180 while making the viscous resistance between the fluid in the through groove 180 have a desired distribution.

[0149] (Embodiment 2)

[0150] Hereinafter, a piezoelectric device related to Embodiment 2 of the present application will be described with reference to the drawings. The structure of the base portion and the reinforcing layer of the piezoelectric device related to Embodiment 2 of the present application is different from that of the piezoelectric device 100 related to Embodiment 1 of the present application, and therefore the same structure as that of the piezoelectric device 100 related to Embodiment 1 of the present application will not be described again.

[0151] Figure 20 is a cross-sectional view of the piezoelectric device related to Embodiment 2 of the present application. In Figure 20 , the same cross-sectional view as Figure 2 is illustrated. As shown in Figure 20 , the piezoelectric device 200 related to Embodiment 2 of the present application has a base portion 110 and a laminated portion 220.

[0152] In the present embodiment, the base portion 110 is composed of only a body base portion 110a. The opening portion 113 of the base portion 110 is covered from above by the laminated portion 220 laminated on one main surface 111 side of the base portion 110.

[0153] The body base portion 110a is composed of SiO2. However, the material constituting the body base portion 110a is not limited to SiO2.

[0154] The laminated portion 220 includes at least the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, and the reinforcing layer 260 above the opening portion 113.

[0155] The laminated portion 220 has a diaphragm portion Mb that is a portion covering the opening portion 113. The diaphragm portion Mb is a portion of the laminated portion 220 that is located inside the opening end portion of the opening portion 113, as viewed in a direction orthogonal to one main surface 111. A through groove 180 that penetrates the diaphragm portion Mb in the up-down direction is provided in the diaphragm portion Mb.

[0156] The reinforcing layer 260 is sandwiched between the single-crystal piezoelectric layer 130 and the lower electrode layer 150. A portion of the reinforcing layer 260 is located above the opening portion 113. An opening portion 263 that communicates with the opening portion 113 of the base portion 110 is formed in the lower surface of the reinforcing layer 260. The opening portion 263 is located above the opening portion 113 and has an upper bottom surface 261. The upper bottom surface 261 of the opening portion 263 constitutes the lower surface of the diaphragm portion Mb.

[0157] In the present embodiment, the reinforcing layer 260 is composed of SiO2. The material of the reinforcing layer 260 is not limited to SiO2, but can be any insulator. For example, the reinforcing layer 260 can also be composed of an organic material having electrical insulation and thermal insulation.

[0158] In this way, the laminated portion 220 includes the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, and the reinforcing layer 260 at least above the opening portion 113.

[0159] As described above, the through groove 180 that penetrates the diaphragm portion Mb in the up-down direction is provided in the diaphragm portion Mb. The width of the through groove 180 narrows downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 260.

[0160] In the single-crystal piezoelectric layer 130 and the reinforcing layer 260, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side. In the present embodiment, the reinforcing layer 260 is the layer located on the lower side, and the single-crystal piezoelectric layer 130 is the layer located on the upper side. The maximum width of the through groove 180 in the reinforcing layer 260 is smaller than the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130.

[0161] Specifically, the single-crystal piezoelectric layer 130 has an end surface 138 that is in contact with the through groove 180. The reinforcing layer 260 has an end surface 268 that is in contact with the through groove 180. The lower electrode layer 150 that is sandwiched between the single-crystal piezoelectric layer 130 and the reinforcing layer 260 has an end surface 158.

[0162] In the present embodiment, the end surface 138 is an upper side end surface, the end surface 268 is a lower side end surface, and the end surface 158 is an intermediate end surface. The inclination angle of the end surface 138 as the upper side end surface is smaller than the inclination angle of the end surface 268 as the lower side end surface. That is, the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130 is the width of the through groove 180 at the position of the lower end of the end surface 138 of the single-crystal piezoelectric layer 130. The maximum width of the through groove 180 in the reinforcing layer 260 is the width of the through groove 180 at the position of the upper end of the end surface 268 of the reinforcing layer 260. The end surface 158 as the intermediate end surface is located on the extension plane of the end surface 268 as the lower side end surface and is continuous with the end surface 268.

[0163] The through groove 180 is narrowest at the end portion on the opening portion 113 side. That is, the through groove 180 is narrowest at the position of the lower end of the end surface 268 of the reinforcing layer 260 in the vertical direction.

[0164] Next, a manufacturing method of a piezoelectric device related to Embodiment 2 of the present application will be described.

[0165] Figure 21 is a cross-sectional view showing a state in which the reinforcing layer is provided to the respective lower surfaces of the lower electrode layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device related to Embodiment 2 of the present application. First, similarly to the manufacturing method of the piezoelectric device 100 related to Embodiment 1 of the present application, the adhesion layer 155 and the lower electrode layer 150 are provided to the lower side of the single-crystal piezoelectric layer 130, respectively. Next, as shown in Figure 21 the reinforcing layer 260 is provided to the respective lower surfaces of the lower electrode layer 150 and the single-crystal piezoelectric layer 130 by a CVD method or a PVD method or the like.

[0166] Figure 22 is a cross-sectional view showing a state in which the lower surface of the reinforcing layer is made flat after the manufacturing method of the piezoelectric device related to Embodiment 2 of the present application. As shown in Figure 22 the lower surface of the reinforcing layer 260 is made flat by CMP or the like.

[0167] Figure 23 is a cross-sectional view showing a state in which the base portion is to be joined to the plurality of layers shown in Figure 22 after the manufacturing method of the piezoelectric device related to Embodiment 2 of the present application. Figure 24 is a cross-sectional view showing a state in which the base portion is joined to the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device related to Embodiment 2 of the present application.

[0168] As shown in Figure 23 and Figure 24 the substrate which is not formed with the opening portion 113 as the base portion 110 is joined to the lower surface of the reinforcing layer 260 by surface activation joining or atomic diffusion joining or the like.

[0169] Figure 25 is a sectional view showing a state after the upper surface of the single-crystal piezoelectric layer is shaved in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. As shown in the drawing, the upper surface of the single-crystal piezoelectric layer 130 is shaved by CMP or the like, so that the single-crystal piezoelectric layer 130 is made to have a desired thickness. Figure 25

[0170] Figure 26 is a sectional view showing a state where the upper electrode layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. As shown in the drawing, the upper electrode layer 140 is provided on a part of the upper surface of the single-crystal piezoelectric layer 130 by a lift-off method, a plating method, or an etching method or the like. Figure 26

[0171] Figure 27 is a sectional view showing a state where the hole portion is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. As shown in the drawing, the hole portion 131 is formed by etching a part of the single-crystal piezoelectric layer 130. Figure 27

[0172] Figure 28 is a sectional view showing a state where the through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. As shown in the drawing, the through groove 180 is formed in the single-crystal piezoelectric layer 130 by etching the single-crystal piezoelectric layer 130. Thus, the end surface 138 which is in contact with the through groove 180 is formed in the single-crystal piezoelectric layer 130. Figure 28

[0173] Figure 29 is a sectional view showing a state where the through groove is provided so as to reach the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. As shown in the drawing, the through groove 180 is formed in the lower electrode layer 150 and the reinforcing layer 260 by etching the lower electrode layer 150 and the reinforcing layer 260, respectively. Thus, the end surface 158 which is in contact with the through groove 180 is formed in the lower electrode layer 150. The end surface 268 which is in contact with the through groove 180 is formed in the reinforcing layer 260. Figure 29

[0174] Figure 30 is a sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 2 of the present application. As shown in the drawing, the opening portion 190 is formed by etching the single-crystal piezoelectric layer 130 and the lower electrode layer 150. Figure 30 ​​​​​As shown, the opening portion 113 is formed in the base 110 and the opening portion 263 is formed in the reinforcing layer 260 by performing deep reactive ion etching or the like from the other main face 112 side of the base 110. Thereby, the diaphragm portion Mb is formed in the piezoelectric device 200 according to the present embodiment.

[0175] Finally, the first lead wire 171 and the second lead wire 172 are respectively provided by a peeling method, a plating method, or an etching method. By the above procedures, the piezoelectric device 200 according to the present embodiment can be manufactured as shown. Figure 20 The piezoelectric device 200 according to the second embodiment of the present application shown in FIG. 2 is different from the piezoelectric device 200 according to the first embodiment of the present application shown in FIG. 1 in that the reinforcing layer 260 is provided in the piezoelectric device 200 according to the second embodiment of the present application.

[0176] As described above, in the piezoelectric device 200 according to the second embodiment of the present application, the width of the through groove 180 is narrowed downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 260. In the single-crystal piezoelectric layer 130 and the reinforcing layer 260, the maximum width of the through groove 180 in the layer on the lower side is smaller than the minimum width of the through groove 180 in the layer on the upper side.

[0177] Thereby, the viscous resistance between the fluid passing through the through groove 180 and the diaphragm portion Mb can be reduced when the diaphragm portion Mb vibrates up and down, and thus the excitation efficiency of the piezoelectric device 200 can be improved.

[0178] In the piezoelectric device 200 according to the second embodiment of the present application, the inclination angle of the end face 138 of the single-crystal piezoelectric layer 130 as the upper side end face is smaller than the inclination angle of the end face 268 of the reinforcing layer 260 as the lower side end face. Thereby, the viscous resistance at the end face 138 of the single-crystal piezoelectric layer 130 can be effectively reduced.

[0179] Hereinafter, a modification of the piezoelectric device 200 according to the second embodiment of the present application will be described.

[0180] Figure 31 is a cross-sectional view showing the structure of the piezoelectric device according to the first modification of the second embodiment of the present application. In Figure 31 , the same cross-sectional view as Figure 20 is shown. As shown in Figure 31 , in the piezoelectric device 200a according to the first modification of the second embodiment of the present application, the inclination angle of the end face 268a of the reinforcing layer 260 as the lower side end face is smaller than the inclination angle of the end face 138a of the single-crystal piezoelectric layer 130 as the upper side end face. The end face 158a of the lower electrode layer 150 as the intermediate end face is located on the extension plane of the end face 268a as the lower side end face and is continuous with the end face 268a. Thereby, the viscous resistance at the end face 268a of the reinforcing layer 260 can be effectively reduced.

[0181] Figure 32is a sectional view showing the structure of a piezoelectric device to which the second modification of Embodiment 2 of the present application relates. In Figure 32 , the same sectional view as Figure 20 is illustrated. As shown in Figure 32 , in the piezoelectric device 200b to which the second modification of Embodiment 2 of the present application relates, in the single-crystal piezoelectric layer 130 and the reinforcing layer 260, the lower side end surface of the layer located on the lower side, which is in contact with the through groove 180, and the upper side end surface of the layer located on the upper side, which is in contact with the through groove 180, are continuous via the intermediate end surface of the upper electrode layer 140 or the lower electrode layer 150, which is in contact with the through groove 180.

[0182] In the present modification, the end surface 268a of the reinforcing layer 260 as the lower side end surface and the end surface 138c of the single-crystal piezoelectric layer 130 as the upper side end surface are continuous via the end surface 158a of the lower electrode layer 150 as the intermediate end surface.

[0183] Thus, the viscous resistance between the fluid passing through the through groove 180 at the time of the up-and-down vibration of the diaphragm portion Mb can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 200b can be improved. Further, the stress concentration to the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be moderated, and thus the occurrence of the interlayer peeling between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be suppressed.

[0184] Figure 33 is a sectional view showing the structure of a piezoelectric device to which the third modification of Embodiment 2 of the present application relates. In Figure 33 , the same sectional view as Figure 20 is illustrated. As shown in Figure 33 , in the piezoelectric device 200c to which the third modification of Embodiment 2 of the present application relates, the inclination angle of the end surface 268a of the reinforcing layer 260 as the lower side end surface is smaller than the inclination angle of the end surface 138c of the single-crystal piezoelectric layer 130 as the upper side end surface. Thus, the viscous resistance at the end surface 268a of the reinforcing layer 260 can be effectively reduced.

[0185] Further, the end surface 268a of the reinforcing layer 260 as the lower side end surface and the end surface 138c of the single-crystal piezoelectric layer 130 as the upper side end surface are continuous via the end surface 158a of the lower electrode layer 150 as the intermediate end surface.

[0186] Thus, the viscous resistance between the fluid passing through the through groove 180 at the time of the up-and-down vibration of the diaphragm portion Mb can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 200c can be improved. Further, the stress concentration to the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be moderated, and thus the occurrence of the interlayer peeling between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be suppressed.

[0187] (Embodiment 3)

[0188] Hereinafter, a piezoelectric device according to Embodiment 3 of the present application will be described with reference to the drawings. The piezoelectric device according to Embodiment 3 of the present application is different from the piezoelectric device 100 according to Embodiment 1 of the present application in that a plurality of reinforcing layers are provided, and thus the same structures as those of the piezoelectric device 100 according to Embodiment 1 of the present application will not be described.

[0189] Figure 34 is a cross-sectional view of the piezoelectric device according to Embodiment 3 of the present application. In Figure 34 , the same cross-sectional view as Figure 2 is illustrated. As shown in Figure 34 , the piezoelectric device 300 according to Embodiment 3 of the present application includes the base 110 and a stacked portion 320.

[0190] The stacked portion 320 includes the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, the reinforcing layer 160, and an additional reinforcing layer 390 at least above the opening portion 113. In the present embodiment, the reinforcing layer is composed of the two layers of the reinforcing layer 160 and the additional reinforcing layer 390.

[0191] The stacked portion 320 has a diaphragm portion Mb that is a portion covering the opening portion 113. The diaphragm portion Mb is a portion of the stacked portion 320 that is located inside the opening end portion of the opening portion 113, as viewed in a direction orthogonal to one major surface 111. The through groove 180 that penetrates the diaphragm portion Mb in the up-down direction is provided in the diaphragm portion Mb.

[0192] The additional reinforcing layer 390 is stacked so as to cover the reinforcing layer 160 from below. In the present embodiment, the additional reinforcing layer 390 is provided so as to be in contact with the lower surface of the reinforcing layer 160. A portion of the lower surface of the additional reinforcing layer 390 is in contact with one major surface 111 of the base 110.

[0193] A portion of the additional reinforcing layer 390 is located above the opening portion 113. A portion of the additional reinforcing layer 390 covers the opening portion 113. The additional reinforcing layer 390 of the portion that does not cover the opening portion 113 is directly connected to the base 110. Alternatively, the additional reinforcing layer 390 of the portion that does not cover the opening portion 113 can not be directly connected to the base 110. The additional reinforcing layer 390 of the portion that does not cover the opening portion 113 can be connected to the base 110 via a metal layer.

[0194] In the present embodiment, the additional reinforcing layer 390 is composed of Si. The base 110 and the additional reinforcing layer 390 are SOI (Silicon on Insulator) substrates. In addition, the material of the additional reinforcing layer 390 is not limited to Si, and can be an insulator. For example, the additional reinforcing layer 390 can also be composed of an organic material having electrical insulation and thermal insulation.

[0195] In this way, the laminated portion 320 includes the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, the reinforcing layer 160, and the additional reinforcing layer 390 at least above the opening portion 113.

[0196] As described above, the diaphragm portion Mb is provided with the through groove 180 that penetrates the diaphragm portion Mb in the up-and-down direction. The width of the through groove 180 narrows as it goes downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer.

[0197] In the single-crystal piezoelectric layer 130 and the reinforcing layer, the maximum width of the through groove 180 in the layer on the lower side is smaller than the minimum width of the through groove 180 in the layer on the upper side. In the present embodiment, the reinforcing layer is the layer on the lower side, and the single-crystal piezoelectric layer 130 is the layer on the upper side. The maximum width of the through groove 180 in the reinforcing layer is smaller than the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130.

[0198] Specifically, the additional reinforcing layer 390 has an end surface 398 that is in contact with the through groove 180. In the present embodiment, the end surface 138 is an upper side end surface, the end surfaces 168 and 398 are lower side end surfaces, and the end surface 158 is an intermediate end surface. The inclination angle of the end surface 138 as the upper side end surface is smaller than the inclination angles of the end surfaces 168 and 398 as the lower side end surfaces. The inclination angles decrease in the order of the end surface 398, the end surface 168, and the end surface 138. That is, the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130 is the width of the through groove 180 at the position of the lower end of the end surface 138 of the single-crystal piezoelectric layer 130. The maximum width of the through groove 180 in the reinforcing layer is the width of the through groove 180 at the position of the upper end of the end surface 168 of the reinforcing layer 160.

[0199] The inclination angle of the end surface 168 of the reinforcing layer 160 is smaller than the inclination angle of the end surface 398 of the additional reinforcing layer 390. A step is formed between the end surface 168 of the reinforcing layer 160 and the end surface 398 of the additional reinforcing layer 390. The lower end of the end surface 168 of the reinforcing layer 160 is located on the upper surface of the additional reinforcing layer 390. A part of the upper surface of the additional reinforcing layer 390 adjacent to the through groove 180 is exposed.

[0200] The through groove 180 is narrowest at the end on the opening portion 113 side. That is, the through groove 180 is narrowest at the position of the lower end of the end surface 398 of the additional reinforcing layer 390 in the up-down direction.

[0201] Next, the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application will be described.

[0202] Figure 35 is a cross-sectional view showing a state in which the plurality of layers are joined to the base portion to which the additional reinforcing layer is laminated in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. Figure 6 is a cross-sectional view showing a state in which the plurality of layers are joined to the base portion to which the additional reinforcing layer is laminated in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. Figure 36 is a cross-sectional view showing a state after the additional reinforcing layer is joined to the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application.

[0203] First, similarly to the manufacturing method of the piezoelectric device 100 according to Embodiment 1 of the present application, the close contact layer 155 and the lower electrode layer 150 are respectively provided on the lower side of the single-crystal piezoelectric layer 130. Further, the reinforcing layer 160 is provided on the respective lower surfaces of the lower electrode layer 150 and the single-crystal piezoelectric layer 130, and the lower surface of the reinforcing layer 160 is made flat.

[0204] Next, as shown in Figure 35 , the additional reinforcing layer 390 is joined to one main surface 111 of the base portion 110 by surface activation joining or atomic diffusion joining or the like.

[0205] As shown in Figure 35 and Figure 36 , the substrate which is the base portion 110 to which the additional reinforcing layer 390 is joined is joined to the lower surface of the reinforcing layer 160 by surface activation joining or atomic diffusion joining or the like.

[0206] Figure 37 is a cross-sectional view showing a state after the upper surface of the single-crystal piezoelectric layer is shaved in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 37 , the upper surface of the single-crystal piezoelectric layer 130 is shaved by CMP or the like, and the single-crystal piezoelectric layer 130 is made to have a desired thickness.

[0207] Figure 38 is a cross-sectional view showing a state in which the upper electrode layer is provided on the upper surface of the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 38 , the upper electrode layer 140 is provided on a part of the upper surface of the single-crystal piezoelectric layer 130 by a lift-off method, a plating method, or an etching method or the like.

[0208] Figure 39is a cross-sectional view showing a state where a hole portion is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 39 , the hole portion 131 is formed by etching a part of the single-crystal piezoelectric layer 130.

[0209] Figure 40 is a cross-sectional view showing a state where a through groove is provided in the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 40 , the through groove 180 is formed in the single-crystal piezoelectric layer 130 by etching the single-crystal piezoelectric layer 130. Thus, the end surface 138 which is in contact with the through groove 180 is formed in the single-crystal piezoelectric layer 130.

[0210] Figure 41 is a cross-sectional view showing a state where the through groove is provided so as to reach the lower surface of the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 41 , the through groove 180 is formed in the lower electrode layer 150 and the reinforcing layer 160 by etching the lower electrode layer 150 and the reinforcing layer 160, respectively. Thus, the end surface 158 which is in contact with the through groove 180 is formed in the lower electrode layer 150. The end surface 168 which is in contact with the through groove 180 is formed in the reinforcing layer 160.

[0211] Figure 42 is a cross-sectional view showing a state where the through groove is provided so as to reach the lower surface of the additional reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 42 , the through groove 180 is formed in the additional reinforcing layer 390 by etching the additional reinforcing layer 390. Thus, the end surface 398 which is in contact with the through groove 180 is formed in the additional reinforcing layer 390.

[0212] Figure 43 is a cross-sectional view showing a state where the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 3 of the present application. As shown in Figure 43 , the opening portion 113 is formed in the base portion 110 by performing deep reactive ion etching or the like from the other main surface 112 side of the base portion 110. Thus, the diaphragm portion Mb is formed in the piezoelectric device 300 according to the present embodiment.

[0213] Finally, the first lead wire 171 and the second lead wire 172 are provided by a peeling method, a plating method, or an etching method, respectively. By the above procedures, the piezoelectric device 300 according to Embodiment 3 of the present application shown in Figure 34 can be manufactured.

[0214] As described above, in the piezoelectric device 300 to which Embodiment 3 of the present application relates, the width of the through groove 180 is narrowed downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer. In the single-crystal piezoelectric layer 130 and the reinforcing layer, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side.

[0215] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb vibrates up and down can be reduced, and thus the excitation efficiency of the piezoelectric device 300 can be improved.

[0216] In the piezoelectric device 300 to which the present embodiment relates, the inclination angle of the end face 138 of the single-crystal piezoelectric layer 130 as the upper side end face is smaller than the inclination angle of each of the end face 168 of the reinforcing layer 160 and the end face 398 of the additional reinforcing layer 390 as the lower side end face. Thus, the viscous resistance at the end face 138 of the single-crystal piezoelectric layer 130 can be effectively reduced.

[0217] Hereinafter, a modification of the piezoelectric device 300 to which Embodiment 3 of the present application relates will be described.

[0218] Figure 44 is a cross-sectional view showing the structure of the piezoelectric device to which the first modification of Embodiment 3 of the present application relates. In Figure 44 , the same cross-sectional view as Figure 34 is shown. As shown in Figure 44 , in the piezoelectric device 300a to which the first modification of Embodiment 3 of the present application relates, the inclination angle of each of the end face 168a of the reinforcing layer 160 and the end face 398a of the additional reinforcing layer 390 as the lower side end face is smaller than the inclination angle of the end face 138a of the single-crystal piezoelectric layer 130 as the upper side end face. The inclination angle decreases in the order of the end face 138a, the end face 168a, and the end face 398a. The end face 158a of the lower electrode layer 150 as the intermediate end face is located on the extension plane of the end face 168a as the lower side end face and is continuous with the end face 168a. Thus, the viscous resistance at each of the end face 168a of the reinforcing layer 160 and the end face 398a of the additional reinforcing layer 390 can be effectively reduced.

[0219] Figure 45 is a cross-sectional view showing the structure of the piezoelectric device to which the second modification of Embodiment 3 of the present application relates. In Figure 45 , the same cross-sectional view as Figure 34 is shown. As shown in Figure 45As shown, in the piezoelectric device 300b according to the second variation of Embodiment 3 of the present invention, the tilt angle of the end face 138b of the single crystal piezoelectric layer 130, which is the upper end face, is smaller than the tilt angle of the end face 168b of the reinforcement layer 160, which is the lower end face, and the tilt angle of the end face 398 of the additional reinforcement layer 390, which are both lower end faces. The tilt angle decreases in the order of end face 398, end face 168b, and end face 138b. In the single crystal piezoelectric layer 130 and the reinforcement layer, the lower end face in the lower layer that is connected to the through groove 180 and the upper end face in the upper layer that is connected to the through groove 180 are continuous via the intermediate end face in the upper electrode layer 140 or the lower electrode layer 150 that is connected to the through groove 180.

[0220] In this modified example, the end face 168b of the reinforcement layer 160, which is the lower end face, and the end face 138b of the single crystal piezoelectric layer 130, which is the upper end face, are continuous via the end face 158b of the lower electrode layer 150, which is the middle end face.

[0221] This effectively reduces the viscous resistance between the diaphragm portion Mb during vertical vibration and the fluid passing through the through groove 180, thereby improving the excitation efficiency of the piezoelectric device 300b. Furthermore, it mitigates stress concentration between the single-crystal piezoelectric layer 130 and the lower electrode layer 150, thereby suppressing interlayer delamination between the single-crystal piezoelectric layer 130 and the lower electrode layer 150.

[0222] Figure 46 This is a cross-sectional view showing the structure of a piezoelectric device according to a third modification of Embodiment 3 of the present invention. Figure 46 In, with Figure 34 The same cross-sectional view is used for illustration. For example... Figure 46 As shown, in the piezoelectric device 300c according to the third modification of Embodiment 3 of the present invention, the tilt angles of the end face 168c of the reinforcement layer 160 (which serves as the lower end face) and the end face 398a of the additional reinforcement layer 390 are smaller than the tilt angle of the end face 138c of the single-crystal piezoelectric layer 130 (which serves as the upper end face). The tilt angles decrease in the order of end face 138c, end face 168c, and end face 398a. As a result, the viscous resistance at the end face 168c of the reinforcement layer 160 and the end face 398a of the additional reinforcement layer 390 can be effectively reduced.

[0223] Furthermore, the end face 168c of the reinforcement layer 160, which is the lower end face, and the end face 138c of the single crystal piezoelectric layer 130, which is the upper end face, are continuous via the end face 158c of the lower electrode layer 150, which is the middle end face.

[0224] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb is vibrating up and down can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 300c can be improved. Further, stress concentration between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be alleviated, and thus occurrence of delamination between the single-crystal piezoelectric layer 130 and the lower electrode layer 150 can be suppressed.

[0225] (Embodiment 4)

[0226] Hereinafter, a piezoelectric device according to Embodiment 4 of the present application will be described with reference to the drawings. The piezoelectric device according to Embodiment 4 of the present application differs from the piezoelectric device 100 according to Embodiment 1 of the present application mainly in the structure of the base portion and the reinforcing layer, and thus the same structures as those of the piezoelectric device 100 according to Embodiment 1 of the present application will not be described again.

[0227] Figure 47 is a cross-sectional view of a piezoelectric device according to Embodiment 4 of the present application. In Figure 47 , the same cross-sectional view as Figure 2 is illustrated. As Figure 47 indicated, the piezoelectric device 400 according to Embodiment 4 of the present application includes a base portion 110 and a laminated portion 420.

[0228] In the present embodiment, the base portion 110 is composed of only the body base portion 110a. The opening portion 113 of the base portion 110 is covered from above by the laminated portion 420 laminated on one main surface 111 side of the base portion 110.

[0229] The laminated portion 420 includes at least the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, and the reinforcing layer 460 above the opening portion 113. The laminated portion 420 further includes an intermediate layer 490.

[0230] The laminated portion 420 has a diaphragm portion Mb that covers a portion of the opening portion 113. The diaphragm portion Mb is a portion of the laminated portion 420 that is located inside the opening end portion of the opening portion 113, as viewed in a direction orthogonal to the one main surface 111. The through groove 180 that passes through the diaphragm portion Mb in the up-and-down direction is provided in the diaphragm portion Mb.

[0231] The reinforcing layer 460 is sandwiched between the single-crystal piezoelectric layer 130 and the upper electrode layer 140. A portion of the reinforcing layer 460 is located above the opening portion 113.

[0232] In the present embodiment, the reinforcing layer 460 is composed of Si3N4. The material of the reinforcing layer 460 is not limited to Si3N4, but can be another insulator. For example, the reinforcing layer 460 can also be composed of an organic material having electrical insulation and thermal insulation. In the case where the reinforcing layer 460 is composed of Si having a low electrical resistivity, the upper electrode layer 140 can not be provided and the reinforcing layer 460 can function as the upper electrode layer.

[0233] In this way, the laminated portion 420 includes the single-crystal piezoelectric layer 130, the upper electrode layer 140, the lower electrode layer 150, and the reinforcing layer 460 at least above the opening portion 113.

[0234] The intermediate layer 490 sandwiches the lower electrode layer 150 between the single-crystal piezoelectric layer 130. An opening portion 493 that communicates with the opening portion 113 of the base portion 110 is formed in a lower surface of the intermediate layer 490. The opening portion 493 is located above the opening portion 113. A portion of a lower surface of the lower electrode layer 150 is exposed through the opening portion 493. The portion of the lower surface of the lower electrode layer 150 exposed through the opening portion 493 constitutes a lower surface of the diaphragm portion Mb.

[0235] The intermediate layer 490 is composed of SiO2. The material of the intermediate layer 490 is not limited to SiO2, but can be another insulator. For example, the intermediate layer 490 can also be composed of an organic material having electrical insulation and thermal insulation.

[0236] As described above, the diaphragm portion Mb is provided with the through groove 180 that penetrates the diaphragm portion Mb in the up-and-down direction. The width of the through groove 180 narrows downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 460.

[0237] In the single-crystal piezoelectric layer 130 and the reinforcing layer 460, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side. In the present embodiment, the single-crystal piezoelectric layer 130 is the layer located on the lower side, and the reinforcing layer 460 is the layer located on the upper side. The maximum width of the through groove 180 in the single-crystal piezoelectric layer 130 is smaller than the minimum width of the through groove 180 in the reinforcing layer 460.

[0238] Specifically, the single-crystal piezoelectric layer 130 has an end surface 138 that interfaces with the through groove 180. The reinforcing layer 460 has an end surface 468 that interfaces with the through groove 180. The upper electrode layer 140 sandwiched between the single-crystal piezoelectric layer 130 and the reinforcing layer 460 has an end surface 148.

[0239] In the present embodiment, the end surface 468 is an upper side end surface, the end surface 138 is a lower side end surface, and the end surface 148 is an intermediate end surface. The inclination angle of the end surface 468 as the upper side end surface is smaller than the inclination angle of the end surface 138 as the lower side end surface. That is, the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130 is the width of the through groove 180 at the position of the lower end of the end surface 138 of the single-crystal piezoelectric layer 130. The maximum width of the through groove 180 in the reinforcing layer 460 is the width of the through groove 180 at the position of the upper end of the end surface 468 of the reinforcing layer 460. The end surface 148 as the intermediate end surface is located on the extension plane of the end surface 468 as the upper side end surface and is continuous with the end surface 468.

[0240] The through groove 180 is narrowest at the end portion on the opening portion 113 side. That is, the through groove 180 is narrowest at the position of the lower end of the end surface 158 of the lower electrode layer 150 in the vertical direction.

[0241] Next, the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application will be described.

[0242] Figure 48 is a cross-sectional view showing a state in which the reinforcing layer is provided on the respective upper surfaces of the upper electrode layer and the single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application. First, in the process shown in Figure 26 The manufacturing method of the piezoelectric device according to Embodiment 4 of the present application is the same as the manufacturing method of the piezoelectric device 200 according to Embodiment 2 of the present application except that the intermediate layer 490 is formed instead of the reinforcing layer 260.

[0243] Next, as shown in Figure 48 the reinforcing layer 460 is provided on the respective upper surfaces of the upper electrode layer 140 and the single-crystal piezoelectric layer 130 by a CVD method or a PVD method or the like.

[0244] Figure 49 is a cross-sectional view showing a state in which the upper surface of the reinforcing layer is made flat in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application. As shown in Figure 49 the upper surface of the reinforcing layer 460 is made flat by CMP or the like.

[0245] Figure 50 is a cross-sectional view showing a state in which the hole portions are respectively provided in the single-crystal piezoelectric layer and the reinforcing layer in the manufacturing method of the piezoelectric device according to Embodiment 4 of the present application. As shown in Figure 50 the hole portion 131 is formed in the single-crystal piezoelectric layer 130 and the hole portions 461 and 462 are respectively formed in the reinforcing layer 460 by etching a part of each of the single-crystal piezoelectric layer 130 and the reinforcing layer 460.

[0246] Figure 51 is a sectional view showing a state in which the through-holes are provided in the reinforcing layer and the upper electrode layer, respectively, in the manufacturing method of the piezoelectric device to which Embodiment 4 of the present application is applied. As shown in Figure 51 by etching the reinforcing layer 460 and the upper electrode layer 140, the through-holes 180 are formed in the reinforcing layer 460 and the upper electrode layer 140, respectively. Thereby, the end surface 468 which is in contact with the through-hole 180 is formed in the reinforcing layer 460. The end surface 148 which is in contact with the through-hole 180 is formed in the upper electrode layer 140.

[0247] Figure 52 is a sectional view showing a state in which the through-holes are provided in a manner reaching the lower surface of the lower electrode layer in the manufacturing method of the piezoelectric device to which Embodiment 4 of the present application is applied. As shown in Figure 52 by etching the single-crystal piezoelectric layer 130 and the lower electrode layer 150, the through-holes 180 are formed in the single-crystal piezoelectric layer 130 and the lower electrode layer 150, respectively. Thereby, the end surface 138 which is in contact with the through-hole 180 is formed in the single-crystal piezoelectric layer 130. The end surface 158 which is in contact with the through-hole 180 is formed in the lower electrode layer 150.

[0248] Figure 53 is a sectional view showing a state in which the opening portions are formed in the manufacturing method of the piezoelectric device to which Embodiment 4 of the present application is applied. As shown in Figure 53 by performing deep reactive ion etching or the like from the other main surface 112 side of the base 110, the opening portion 113 is formed in the base 110, and the opening portion 493 is formed in the intermediate layer 490. Thereby, the diaphragm portion Mb is formed in the piezoelectric device 400 to which the present embodiment is applied.

[0249] Finally, the first lead wire 171 and the second lead wire 172 are provided by a peeling method, a plating method, or an etching method, respectively. By the above procedures, the piezoelectric device 400 to which Embodiment 4 of the present application is applied as shown in Figure 47 is manufactured.

[0250] As described above, in the piezoelectric device 400 to which Embodiment 4 of the present application is applied, the width of the through-hole 180 is narrowed in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 460 as it goes downward. In the single-crystal piezoelectric layer 130 and the reinforcing layer 460, the maximum width of the through-hole 180 in the layer located on the lower side is smaller than the minimum width of the through-hole 180 in the layer located on the upper side.

[0251] Thereby, the viscous resistance between the fluid passing through the through-hole 180 and the diaphragm portion Mb at the time of the up-and-down vibration can be reduced, and thus the excitation efficiency of the piezoelectric device 400 can be improved.

[0252] In the piezoelectric device 400 according to the embodiment 4, the inclination angle of the end surface 468 of the reinforcing layer 460 as the upper side end surface is smaller than the inclination angle of the end surface 138 of the single-crystal piezoelectric layer 130 as the lower side end surface. Thus, the viscous resistance at the end surface 468 of the reinforcing layer 460 can be effectively reduced.

[0253] Next, a modification of the piezoelectric device 400 according to the embodiment 4 of the present application will be described.

[0254] Figure 54 is a cross-sectional view showing the structure of a piezoelectric device according to a first modification of the embodiment 4 of the present application. In Figure 54 , the same cross-sectional view as Figure 47 is shown.

[0255] As shown in Figure 54 , in the piezoelectric device 400a according to the first modification of the embodiment 4 of the present application, the inclination angle of the end surface 138a of the single-crystal piezoelectric layer 130 as the lower side end surface is smaller than the inclination angle of the end surface 468a of the reinforcing layer 460 as the upper side end surface. The end surface 148a of the upper electrode layer 140 as the intermediate end surface is located on the extension plane of the end surface 468a as the upper side end surface, and is continuous with the end surface 468a. The end surface 158a of the lower electrode layer 150 is located on the extension plane of the end surface 138a as the lower side end surface, and is continuous with the end surface 138a. Thus, the viscous resistance at the end surface 138a of the single-crystal piezoelectric layer 130 can be effectively reduced.

[0256] Figure 55 is a cross-sectional view showing the structure of a piezoelectric device according to a second modification of the embodiment 4 of the present application. In Figure 55 , the same cross-sectional view as Figure 47 is shown. As shown in Figure 55 , in the piezoelectric device 400b according to the second modification of the embodiment 4 of the present application, in the single-crystal piezoelectric layer 130 and the reinforcing layer 460, the lower side end surface in the layer located on the lower side, which is in contact with the through groove 180, and the upper side end surface in the layer located on the upper side, which is in contact with the through groove 180, are continuous via the intermediate end surface in the upper electrode layer 140 or the lower electrode layer 150, which is in contact with the through groove 180.

[0257] In the present modification, the end surface 138 of the single-crystal piezoelectric layer 130 as the lower side end surface and the end surface 468b of the reinforcing layer 460 as the upper side end surface are continuous via the end surface 148b of the upper electrode layer 140 as the intermediate end surface.

[0258] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb is vibrated up and down can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 400b can be improved. Further, stress concentration between the single-crystal piezoelectric layer 130 and the upper electrode layer 140 can be alleviated, and thus occurrence of interlayer peeling between the single-crystal piezoelectric layer 130 and the upper electrode layer 140 can be suppressed.

[0259] Figure 56 is a cross-sectional view illustrating a structure of a piezoelectric device according to a third modification of Embodiment 4 of the present application. In Figure 56 , the same cross-sectional view as Figure 47 is illustrated. As Figure 56 illustrated, in the piezoelectric device 400c according to the third modification of Embodiment 4 of the present application, the inclination angle of the end surface 138c of the single-crystal piezoelectric layer 130 as the lower side end surface is smaller than the inclination angle of the end surface 468c of the reinforcing layer 460 as the upper side end surface. Thus, the viscous resistance at the end surface 138c of the single-crystal piezoelectric layer 130 can be effectively reduced.

[0260] Further, the end surface 138c of the single-crystal piezoelectric layer 130 as the lower side end surface and the end surface 468c of the reinforcing layer 460 as the upper side end surface are continuous via the end surface 148c of the upper electrode layer 140 as the intermediate end surface. The end surface 158c of the lower electrode layer 150 is located on an extension plane of the end surface 138c as the lower side end surface and is continuous with the end surface 138c.

[0261] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb is vibrated up and down can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 400c can be improved. Further, stress concentration between the single-crystal piezoelectric layer 130 and the upper electrode layer 140 can be alleviated, and thus occurrence of interlayer peeling between the single-crystal piezoelectric layer 130 and the upper electrode layer 140 can be suppressed.

[0262] (Embodiment 5)

[0263] Hereinafter, a piezoelectric device according to Embodiment 5 of the present application will be described with reference to the drawings. The piezoelectric device according to Embodiment 5 of the present application is different from the piezoelectric device 100 according to Embodiment 1 of the present application in that the reinforcing layer functions as the lower electrode layer, and thus the same structure as the piezoelectric device 100 according to Embodiment 1 of the present application will not be described again.

[0264] Figure 57 is a cross-sectional view of a piezoelectric device according to Embodiment 5 of the present application. In Figure 57 , the same cross-sectional view as Figure 2 is illustrated. As Figure 57As shown, the piezoelectric device 500 according to Embodiment 5 of the present application includes the base 110 and the stacked portion 520.

[0265] The stacked portion 520 includes the single-crystal piezoelectric layer 130, the upper electrode layer 140, and the reinforcing layer 560 at least above the opening portion 113.

[0266] The stacked portion 520 has a diaphragm portion Mb that covers a portion of the opening portion 113. The diaphragm portion Mb is a portion of the stacked portion 520 that is located inside the opening end portion of the opening portion 113, as viewed in a direction orthogonal to the one main surface 111. The through groove 180 that penetrates the diaphragm portion Mb in the up-down direction is provided in the diaphragm portion Mb.

[0267] The upper electrode layer 140 is disposed adjacent to the single-crystal piezoelectric layer 130. The upper electrode layer 140 is disposed on the upper side of the single-crystal piezoelectric layer 130.

[0268] The reinforcing layer 560 opposes at least a portion of the upper electrode layer 140 with the single-crystal piezoelectric layer 130 interposed therebetween. The reinforcing layer 560 is adjacent to the lower surface of the single-crystal piezoelectric layer 130.

[0269] A portion of the reinforcing layer 560 is located above the opening portion 113. A portion of the reinforcing layer 560 covers the opening portion 113. The reinforcing layer 560 that does not cover the portion of the opening portion 113 is directly connected to the base 110. Alternatively, the reinforcing layer 560 that does not cover the portion of the opening portion 113 can not be directly connected to the base 110. The reinforcing layer 560 that does not cover the portion of the opening portion 113 can be connected to the base 110 via a metal layer.

[0270] The reinforcing layer 560 is composed of Si. The base 110 and the reinforcing layer 560 are SOI substrates. The material of the reinforcing layer 560 is not limited to Si, and can be any material that has electrical conductivity.

[0271] The width of the through groove 180 narrows downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 560. In the single-crystal piezoelectric layer 130 and the reinforcing layer 560, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side. In this embodiment, the reinforcing layer 560 is the layer located on the lower side, and the single-crystal piezoelectric layer 130 is the layer located on the upper side. The maximum width of the through groove 180 in the reinforcing layer 560 is smaller than the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130.

[0272] The reinforcing layer 560 has an end face 568 that connects to the through groove 180. In this embodiment, end face 138 is the upper end face, and end face 568 is the lower end face. The inclination angle of the end face 138, which is the upper end face, is smaller than the inclination angle of the end face 568, which is the lower end face. Alternatively, the inclination angle of the end face 568, which is the lower end face, may be smaller than the inclination angle of the end face 138, which is the upper end face.

[0273] The minimum width of the through-groove 180 in the single-crystal piezoelectric layer 130 is the width of the through-groove 180 located at the lower end of the end face 138 of the single-crystal piezoelectric layer 130. The maximum width of the through-groove 180 in the reinforcement layer 560 is the width of the through-groove 180 located at the upper end of the end face 568 of the reinforcement layer 560. For example... Figure 57 As shown, the width of the through groove 180 narrows from the upper end to the lower end of the through groove 180.

[0274] The through groove 180 is narrowest at its end on the side of the opening 113. That is, the through groove 180 is narrowest at the lower end of the end face 568 of the vertical reinforcing layer 560.

[0275] The manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention will be described below. Figure 58 This is a cross-sectional view showing the state in which a single-crystal piezoelectric layer is bonded to an SOI substrate in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention. Figure 58 As shown, the SOI substrate is bonded to the lower surface of the single crystal piezoelectric layer 130 by surface activation bonding or atomic diffusion bonding.

[0276] Figure 59 This is a cross-sectional view showing the state after the upper surface of the single-crystal piezoelectric layer has been removed in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention. Figure 59 As shown, the upper surface of the single-crystal piezoelectric layer 130 is removed by CMP or similar methods to achieve the desired thickness. Alternatively, a release layer can be formed on the upper surface side of the single-crystal piezoelectric layer 130 beforehand by ion implantation. In this case, the release layer is removed before the upper surface of the single-crystal piezoelectric layer 130 is removed by cutting or CMP, thereby facilitating the adjustment of the thickness of the single-crystal piezoelectric layer 130. The thickness of the single-crystal piezoelectric layer 130 is adjusted to obtain the desired excitation of the single-crystal piezoelectric layer 130 caused by the application of voltage.

[0277] Figure 60 This is a cross-sectional view showing a state in which an upper electrode layer is provided on the upper surface of a single-crystal piezoelectric layer in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention. Figure 60As shown, an upper electrode layer 140 is formed on a portion of the upper surface of the single crystal piezoelectric layer 130 by means of peeling, plating or etching.

[0278] Figure 61 This is a cross-sectional view showing a state in which holes are provided in the single-crystal piezoelectric layer during the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention. Figure 61 As shown, a hole 131 is formed by etching a portion of the single-crystal piezoelectric layer 130.

[0279] Figure 62 This is a cross-sectional view showing a state in which a through-groove is provided in the single-crystal piezoelectric layer during the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention. Figure 62 As shown, a through-groove 180 is formed in the single-crystal piezoelectric layer 130 by etching. As a result, an end face 138 is formed in the single-crystal piezoelectric layer 130 that connects with the through-groove 180.

[0280] Figure 63 This is a cross-sectional view showing a state in which a through-groove is provided in the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention, so as to reach the lower surface of the reinforcing layer. Figure 63 As shown, a through-groove 180 is formed in the reinforcement layer 560 by etching. As a result, an end face 568 is formed in the reinforcement layer 560 that connects with the through-groove 180.

[0281] Figure 64 This is a cross-sectional view showing the state in which an opening is formed during the manufacturing method of the piezoelectric device according to Embodiment 5 of the present invention. Figure 64 As shown, an opening 113 is formed in the base 110 from the other main surface 112 side of the base 110 by deep reactive ion etching or the like. Thus, a diaphragm portion Mb is formed in the piezoelectric device 500 according to this embodiment.

[0282] Finally, the first lead wire 171 and the second lead wire 172 are respectively formed by methods such as stripping, plating, or etching. Through the above processes, a product is manufactured as follows. Figure 57 The piezoelectric device 500 shown is related to Embodiment 5 of the present invention.

[0283] As described above, in the piezoelectric device 500 according to Embodiment 5 of the present invention, the width of the through-groove 180 narrows downwards in each of the single-crystal piezoelectric layer 130 and the reinforcement layer 560. In the single-crystal piezoelectric layer 130 and the reinforcement layer 560, the maximum width of the through-groove 180 in the lower layer is smaller than the minimum width of the through-groove 180 in the upper layer.

[0284] Thus, the viscous resistance between the diaphragm portion Mb and the fluid passing through the through groove 180 when the diaphragm portion Mb is vibrating up and down can be reduced, and thus the excitation efficiency of the piezoelectric device 500 can be improved.

[0285] In the piezoelectric device 500 according to the present embodiment, the inclination angle of the end surface 138 of the single-crystal piezoelectric layer 130 as the upper side end surface is smaller than the inclination angle of the end surface 568 of the reinforcing layer 560 as the lower side end surface. Thus, the viscous resistance at the end surface 138 of the single-crystal piezoelectric layer 130 can be effectively reduced. Further, by causing the reinforcing layer 560 to function as the lower electrode layer, the structure of the piezoelectric device 500 can be simplified.

[0286] (Embodiment 6)

[0287] Hereinafter, a piezoelectric device according to Embodiment 6 of the present application will be described with reference to the drawings. The piezoelectric device according to Embodiment 6 of the present application is different from the piezoelectric device 400 according to Embodiment 4 of the present application in that the reinforcing layer functions as the upper electrode layer, and thus the same structure as the piezoelectric device 400 according to Embodiment 4 of the present application will not be described.

[0288] Figure 65 is a cross-sectional view of the piezoelectric device according to Embodiment 6 of the present application. In Figure 65 , the same cross-sectional view as Figure 2 is illustrated. As shown in Figure 65 , the piezoelectric device 600 according to Embodiment 6 of the present application includes a base portion 110 and a laminated portion 620.

[0289] In the present embodiment, the base portion 110 is composed of only the body base portion 110a. The opening portion 113 of the base portion 110 is covered from above by the laminated portion 620 laminated on one main surface 111 side of the base portion 110.

[0290] The laminated portion 620 includes at least the single-crystal piezoelectric layer 130, the lower electrode layer 150, and the reinforcing layer 660 above the opening portion 113. The laminated portion 620 further includes the intermediate layer 490.

[0291] The laminated portion 620 has a diaphragm portion Mb as a portion covering the opening portion 113. The diaphragm portion Mb is a portion of the laminated portion 620 located inside the opening end portion of the opening portion 113, as viewed in a direction orthogonal to the one main surface 111. The through groove 180 passing through the diaphragm portion Mb in the up-and-down direction is provided in the diaphragm portion Mb.

[0292] The lower electrode layer 150 is disposed adjacent to the single-crystal piezoelectric layer 130. The lower electrode layer 150 is disposed on the lower side of the single-crystal piezoelectric layer 130.

[0293] The reinforcing layer 660 opposes at least a portion of the lower electrode layer 150 across the single-crystal piezoelectric layer 130. The reinforcing layer 660 is adjacent to the upper surface of the single-crystal piezoelectric layer 130. A portion of the reinforcing layer 660 is positioned above the opening portion 113. A portion of the reinforcing layer 660 covers the opening portion 113.

[0294] The reinforcing layer 660 is composed of Si. The material of the reinforcing layer 660 is not limited to Si, as long as it is a material having electrical conductivity.

[0295] The width of the through groove 180 narrows in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 660 as it goes downward. In the single-crystal piezoelectric layer 130 and the reinforcing layer 660, the maximum width of the through groove 180 in the layer positioned on the lower side is smaller than the minimum width of the through groove 180 in the layer positioned on the upper side. In the present embodiment, the single-crystal piezoelectric layer 130 is the layer positioned on the lower side, and the reinforcing layer 660 is the layer positioned on the upper side. The maximum width of the through groove 180 in the single-crystal piezoelectric layer 130 is smaller than the minimum width of the through groove 180 in the reinforcing layer 660.

[0296] The reinforcing layer 660 has an end surface 668 that is in contact with the through groove 180. In the present embodiment, the end surface 668 is an upper side end surface, and the end surface 138 is a lower side end surface. The inclination angle of the end surface 668 as the upper side end surface is smaller than the inclination angle of the end surface 138 as the lower side end surface. Alternatively, the inclination angle of the end surface 138 as the lower side end surface can be smaller than the inclination angle of the end surface 668 as the upper side end surface.

[0297] The minimum width of the through groove 180 in the single-crystal piezoelectric layer 130 is the width of the through groove 180 at the position of the lower end of the end surface 138 of the single-crystal piezoelectric layer 130. The maximum width of the through groove 180 in the reinforcing layer 660 is the width of the through groove 180 at the position of the upper end of the end surface 668 of the reinforcing layer 660. As shown in FIG. 6B, the width of the through groove 180 narrows as it goes from the upper end to the lower end of the through groove 180. Figure 65

[0298] The through groove 180 is narrowest at the end portion on the side of the opening portion 113. That is, the through groove 180 is narrowest at the position of the lower end of the end surface 158 of the lower electrode layer 150 in the vertical direction.

[0299] Next, a manufacturing method of a piezoelectric device according to Embodiment 6 of the present application will be described.

[0300] Figure 66 is a cross-sectional view showing a state in which a reinforcing layer is provided on the upper surface of a single-crystal piezoelectric layer in the manufacturing method of a piezoelectric device according to Embodiment 6 of the present application. First, in the manufacturing method of the piezoelectric device 200 according to Embodiment 2 of the present application, the single-crystal piezoelectric layer 130 is provided on the lower electrode layer 150. Next, the reinforcing layer 660 is provided on the upper surface of the single-crystal piezoelectric layer 130. The reinforcing layer 660 is composed of Si. The reinforcing layer 660 is provided so as to cover the opening portion 113. Figure 25 ​In the process shown, except that an intermediate layer 490 is formed to replace the reinforcing layer 260, the manufacturing method of the piezoelectric device according to Embodiment 6 of the present invention is the same as the manufacturing method of the piezoelectric device 200 according to Embodiment 2 of the present invention.

[0301] Next, as Figure 66 As shown, an enhancement layer 660 is formed on the upper surface of the single-crystal piezoelectric layer 130 by means of CVD or PVD.

[0302] Figure 67 This is a cross-sectional view showing a state in which holes are provided in both the single-crystal piezoelectric layer and the reinforcement layer in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present invention. Figure 67 As shown, by etching a portion of the single-crystal piezoelectric layer 130 and a portion of the reinforcement layer 660, a hole 131 is formed in the single-crystal piezoelectric layer 130 and a hole 661 is formed in the reinforcement layer 660.

[0303] Figure 68 This is a cross-sectional view showing the state in which a through-groove is provided in the reinforcing layer during the manufacturing method of the piezoelectric device according to Embodiment 6 of the present invention. Figure 68 As shown, a through-groove 180 is formed in the reinforcement layer 660 by etching. As a result, an end face 668 is formed in the reinforcement layer 660 that connects with the through-groove 180.

[0304] Figure 69 This is a cross-sectional view showing a state in which a through-groove is provided in the manufacturing method of the piezoelectric device according to Embodiment 6 of the present invention, so as to reach the lower surface of the lower electrode layer. Figure 69 As shown, through-grooves 180 are formed in the single-crystal piezoelectric layer 130 and the lower electrode layer 150 by etching. This creates an end face 138 in the single-crystal piezoelectric layer 130 that connects to the through-grooves 180. The lower electrode layer 150 also forms an end face 158 that connects to the through-grooves 180.

[0305] Figure 70 This is a cross-sectional view showing the state in which an opening is formed during the manufacturing method of the piezoelectric device according to Embodiment 6 of the present invention. Figure 70 As shown, an opening 113 is formed in the base 110 by performing deep reactive ion etching or the like from the other main surface 112 side of the base 110, and an opening 493 is formed in the intermediate layer 490. Thus, a diaphragm portion Mb is formed in the piezoelectric device 600 according to this embodiment.

[0306] Finally, the first lead wire 171 and the second lead wire 172 are respectively formed by methods such as stripping, plating, or etching. Through the above processes, a device such as... Figure 65Embodiment 6 of the present application shown relates to a piezoelectric device 600.

[0307] As described above, in the piezoelectric device 600 to which Embodiment 6 of the present application relates, the width of the through groove 180 is narrowed as it goes downward in each of the single-crystal piezoelectric layer 130 and the reinforcing layer 660. In the single-crystal piezoelectric layer 130 and the reinforcing layer 660, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side.

[0308] Thus, the viscous resistance between the fluid passing through the through groove 180 and the diaphragm portion Mb can be reduced when the diaphragm portion Mb vibrates up and down, and thus the excitation efficiency of the piezoelectric device 600 can be improved.

[0309] In the piezoelectric device 600 to which the present embodiment relates, the inclination angle of the end surface 668 of the reinforcing layer 660 as the upper side end surface is smaller than the inclination angle of the end surface 138 of the single-crystal piezoelectric layer 130 as the lower side end surface. Thus, the viscous resistance at the end surface 668 of the reinforcing layer 660 can be effectively reduced. Further, by causing the reinforcing layer 660 to function as the upper electrode layer, the structure of the piezoelectric device 600 can be simplified.

[0310] (Embodiment 7)

[0311] Hereinafter, a piezoelectric device to which Embodiment 7 of the present application relates will be described with reference to the drawings. The piezoelectric device to which Embodiment 7 of the present application relates is different from the piezoelectric device 100 to which Embodiment 1 of the present application relates in that the width of the through groove in the reinforcing layer is widened as it goes downward, and thus the same structure as the piezoelectric device 100 to which Embodiment 1 of the present application relates will not be described again.

[0312] Figure 71 is a cross-sectional view of the piezoelectric device to which Embodiment 7 of the present application relates. In Figure 71 , the same cross-sectional view as Figure 2 is illustrated. As Figure 71 shown, the piezoelectric device 700 to which Embodiment 7 of the present application relates has the base portion 110 and the laminated portion 120.

[0313] In the present embodiment, the width of the through groove 180 in the single-crystal piezoelectric layer 130 is narrowed as it goes downward. The width of the through groove 180 in the reinforcing layer 160 is widened as it goes downward.

[0314] In the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the maximum width of the through groove 180 in the layer located on the lower side is smaller than the minimum width of the through groove 180 in the layer located on the upper side. In the present embodiment, the reinforcing layer 160 is the layer located on the lower side, and the single-crystal piezoelectric layer 130 is the layer located on the upper side. The maximum width of the through groove 180 in the reinforcing layer 160 is smaller than the minimum width of the through groove 180 in the single-crystal piezoelectric layer 130.

[0315] The through groove 180 is narrowest at the lower electrode layer 150. Specifically, the through groove 180 is narrowest at a position of the upper end of the end surface 158 of the lower electrode layer 150 in the vertical direction.

[0316] Next, a manufacturing method of a piezoelectric device according to Embodiment 7 of the present application will be described.

[0317] Figure 72 is a cross-sectional view showing a state in which the opening portion is formed in the manufacturing method of the piezoelectric device according to Embodiment 7 of the present application. First, in the process shown in Figure 12 In the process shown in

[0318] As shown in Figure 72 The opening portion 113 is formed in the base 110 by deep reactive ion etching or the like from the other main surface 112 side of the base 110. Thus, the diaphragm portion Mb is formed in the piezoelectric device 700 according to the present embodiment.

[0319] Figure 73 is a cross-sectional view showing a state in which the through groove is provided so as to reach the upper surface of the lower electrode layer from the opening portion side in the manufacturing method of the piezoelectric device according to Embodiment 7 of the present application. As shown in Figure 73 The through groove 180 is formed in the lower electrode layer 150 and the reinforcing layer 160 by etching the lower electrode layer 150 and the reinforcing layer 160 from the opening portion 113 side. Thus, the end surface 158 that is in contact with the through groove 180 is formed in the lower electrode layer 150. The end surface 168 that is in contact with the through groove 180 is formed in the reinforcing layer 160.

[0320] As shown in Figure 73In the single-crystal piezoelectric layer 130 and the reinforcing layer 160, the maximum width of the through groove 180 in the layer on the upper side is du, the minimum width of the through groove 180 in the layer on the upper side is dm3, and the maximum width of the through groove 180 in the layer on the lower side is db. The relationship du > dm3 > db is satisfied. The minimum width of the through groove 180 in the lower electrode layer 150 is dm4. The relationship db > dm4 is satisfied.

[0321] Finally, the first lead wire 171 and the second lead wire 172 are respectively provided by a peeling method, a plating method, or an etching method. Through the above procedures, a piezoelectric device 700 as shown in FIG. 7 can be manufactured. Figure 73 Embodiment 7 of the present application as shown relates to a piezoelectric device 700.

[0322] Figure 74 is a schematic view of the longitudinal sectional shape of the through groove of the diaphragm portion in the piezoelectric device to which Embodiment 7 of the present application relates. As shown in Figure 74 By satisfying the relationship du > dm3 > db > dm4, the viscous resistance of the fluid F1 immersed in the through groove 180 from the upper side and the viscous resistance of the fluid F2 immersed in the through groove 180 from the lower side can be respectively reduced.

[0323] Thus, the viscous resistance between the fluid passing through the through groove 180 and the diaphragm portion Mb when the diaphragm portion Mb vibrates up and down can be effectively reduced, and thus the excitation efficiency of the piezoelectric device 700 can be improved.

[0324] In the above description of the embodiments, structures that can be combined can be combined with each other.

[0325] It should be considered that the embodiments disclosed herein are illustrative and not restrictive in all aspects. The scope of the present application is not shown by the above description, but is shown by the claims, and the intention is to include all modifications within the meaning and scope of the claims and equivalent thereof.

[0326] Explanation of Reference Numerals

[0327] 100, 100a, 100b, 100c, 200, 200a, 200b, 200c, 300, 300a, 300b, 300c, 400, 400a, 400b, 400c, 500, 600, 700: piezoelectric device, 110: base, 110a: body base, 110b: surface layer base, 111: one main surface, 112: the other main surface, 113, 263, 493: opening portion, 120, 220, 320, 420, 520, 620: laminated portion, 130: single-crystal piezoelectric layer, 131, 461, 462, 661: hole portion, 138, 138a, 138b, 138c, 148, 148a, 148b, 148c, 158, 158a, 158b, 158c, 168, 168a, 168b, 168c, 268, 268a, 398, 398a, 468, 468a, 468b, 468c, 568, 668: end surface, 140: upper electrode layer, 150: lower electrode layer, 155: adhesion layer, 160, 260, 460, 560, 660: reinforcing layer, 171: first lead wire, 172: second lead wire, 180: through groove, 261: upper bottom surface, 390: additional reinforcing layer, 490: intermediate layer, Mb: diaphragm portion.

Claims

1. A piezoelectric device comprising: A base comprising a main surface and another main surface located on the opposite side of the first main surface, and having an opening extending from the first main surface to the other main surface; and The laminated portion, which is stacked on one of the main surfaces of the base, covers the opening from above. The laminated portion includes, at least above the opening, a single-crystal piezoelectric layer, an upper electrode layer disposed above the single-crystal piezoelectric layer, a lower electrode layer opposite to at least a portion of the upper electrode layer via the single-crystal piezoelectric layer, and a reinforcement layer sandwiching the upper electrode layer or the lower electrode layer between itself and the single-crystal piezoelectric layer, and has a film portion covering the opening. A through groove extending vertically is provided in the diaphragm portion. The width of the through-groove in the single-crystal piezoelectric layer narrows as it moves downwards. In the single-crystal piezoelectric layer and the reinforcement layer, the maximum width of the through-groove in the lower layer is smaller than the minimum width of the through-groove in the upper layer. in, In the single-crystal piezoelectric layer and the reinforcement layer, the lower end face of the lower layer that connects to the through-groove and the upper end face of the upper layer that connects to the through-groove are continuous via the middle end face of the upper electrode layer or the lower electrode layer that connects to the through-groove. The tilt angle of the lower end face is smaller than that of the upper end face.

2. A piezoelectric device, comprising: A base comprising a main surface and another main surface located on the opposite side of the first main surface, and having an opening extending from the first main surface to the other main surface; and The laminated portion, which is stacked on one of the main surfaces of the base, covers the opening from above. The laminated portion includes, at least above the opening, a single-crystal piezoelectric layer, an upper electrode layer disposed above the single-crystal piezoelectric layer, a lower electrode layer opposite to at least a portion of the upper electrode layer via the single-crystal piezoelectric layer, and a reinforcement layer sandwiching the upper electrode layer or the lower electrode layer between itself and the single-crystal piezoelectric layer, and has a film portion covering the opening. A through groove extending vertically is provided in the diaphragm portion. The width of the through-groove in the single-crystal piezoelectric layer narrows as it moves downwards. In the single-crystal piezoelectric layer and the reinforcement layer, the maximum width of the through-groove in the lower layer is smaller than the minimum width of the through-groove in the upper layer. in, In the single-crystal piezoelectric layer and the reinforcement layer, the lower end face of the lower layer that connects to the through-groove and the upper end face of the upper layer that connects to the through-groove are continuous via the middle end face of the upper electrode layer or the lower electrode layer that connects to the through-groove. The inclination angle of the upper end face is smaller than that of the lower end face.

3. The piezoelectric device according to claim 1 or 2, wherein, The width of the through-slot in the reinforcing layer narrows as it moves downwards.

4. The piezoelectric device according to claim 1 or 2, wherein, The single-crystal piezoelectric layer is composed of lithium tantalate or lithium niobate.

5. A piezoelectric device, comprising: A base comprising a main surface and another main surface located on the opposite side of the first main surface, and having an opening extending from the first main surface to the other main surface; and The laminated portion, which is stacked on one of the main surfaces of the base, covers the opening from above. The laminated portion includes, at least above the opening, a single-crystal piezoelectric layer, an electrode layer disposed adjacent to the single-crystal piezoelectric layer, and a conductive reinforcement layer that is separated from at least a portion of the electrode layer by the single-crystal piezoelectric layer, and has a film portion covering the opening. A through groove extending vertically is provided in the diaphragm portion. The width of the through-groove continuously narrows downwards in both the single-crystal piezoelectric layer and the reinforcing layer. In the single-crystal piezoelectric layer and the reinforcement layer, the maximum width of the through-groove in the lower layer is smaller than the minimum width of the through-groove in the upper layer.

6. The piezoelectric device according to claim 5, wherein, In the single-crystal piezoelectric layer and the reinforcing layer, the inclination angle of the lower end face of the lower layer that connects to the through groove is smaller than the inclination angle of the upper end face of the upper layer that connects to the through groove.

7. The piezoelectric device according to claim 5, wherein, In the single-crystal piezoelectric layer and the reinforcing layer, the inclination angle of the upper end face of the upper layer that connects to the through groove is smaller than the inclination angle of the lower end face of the lower layer that connects to the through groove.

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