Piezoelectric element, piezoelectric device, and method for manufacturing piezoelectric element

Abstract

The invention provides a piezoelectric element, a piezoelectric device, and a method for manufacturing the piezoelectric element. Wherein the plurality of vibration regions (22) are separated from each other by slits (41), and the slits (41) are formed in a state in which the vibration regions (22) constitute a tapered portion (42) in which the width becomes narrower from one surface (22a) of the vibration regions (22) on the opposite side to the support body (10) toward the other surface (22b) of the vibration regions (22) on the opposite side to the one surface (22a). The electrode film (60) is disposed further toward the inside than the slit (41) in the normal direction to the one surface (22a), and an angle ([theta] 1) formed by a side surface (22c) constituting the tapered portion (42) in the vibration region (22) and surfaces (22b, Sv) parallel to the one surface (22a) is 39-81 DEG.

Description

[0001] This application is a divisional application of the original application filed on October 29, 2021, with application number 202180069780.3 and invention title "Piezoelectric element, piezoelectric device and method for manufacturing piezoelectric element". Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2020-184022 filed on November 3, 2020 and Japanese Patent Application No. 2021-16149 filed on February 3, 2021, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a piezoelectric element, a piezoelectric device, and a method for manufacturing a piezoelectric element whose vibration region is cantilevered. Background Technology

[0004] Previously, piezoelectric elements in which the vibration region is cantilevered by a support body have been proposed (for example, see Patent Document 1). Specifically, the piezoelectric element includes a support body and a vibration section disposed on the support body. The vibration section is configured to have a piezoelectric film and an electrode film connected to the piezoelectric film. Furthermore, the piezoelectric film is made of aluminum nitride (hereinafter also simply referred to as AlN).

[0005] A recess is formed on the support body to float the inner edge of the vibrating part. Thus, a floating region is formed in the vibrating part, which floats on the recess. Furthermore, in this piezoelectric element, a vibration region is formed by dividing the floating region into slits. That is, a vibration region cantilevered by the support body is formed.

[0006] Such a piezoelectric element is manufactured as follows: A piezoelectric film and an electrode film are formed on a support. Next, a slit is formed on the piezoelectric film to form a vibration region component. Then, a recess is formed on the support, causing the vibration region component to float and become the vibration region, thereby manufacturing the aforementioned piezoelectric element.

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 5936154 Summary of the Invention

[0008] Furthermore, in the aforementioned piezoelectric elements, the use of scandium aluminum nitride (hereinafter, also referred to as ScAlN), which has high piezoelectric properties, is being explored as the piezoelectric film. However, ScAlN is a difficult-to-etch material. Therefore, if the piezoelectric element is manufactured using the same manufacturing method as when AlN is used as the piezoelectric film, the slit cannot be properly formed during the slit formation process, and the shape of the vibration region may deviate.

[0009] The purpose of this disclosure is to provide a piezoelectric element, a piezoelectric device, and a method for manufacturing a piezoelectric element that appropriately forms a slit.

[0010] According to one aspect of this disclosure, a piezoelectric element comprises: a support body; and a vibrating part, which is configured to include a piezoelectric film made of scandium aluminum nitride disposed on the support body and connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film, having a support region supported by the support body and multiple vibrating regions connected to the support region and floating from the support body, and outputting a charge-based pressure detection signal; the multiple vibrating regions are separated from each other by slits, the slits being formed in a state where the width narrows from one side of the vibrating region opposite to the support body side to the other side opposite to that side, the electrode film being disposed in a position closer to the inside of the slit in the normal direction with respect to one side, and the angle between the side of the vibrating region constituting the cone and the surface parallel to one side being set to 39° to 81°.

[0011] Accordingly, the angle formed by the vibration region is set to 39°–81°. This suppresses the decrease in processability during slit formation, ensuring proper slit formation. Consequently, it suppresses the decrease in detection sensitivity.

[0012] In addition, according to another aspect of this disclosure, a piezoelectric device having a piezoelectric element includes: the piezoelectric element as described in one aspect of this disclosure; and a housing having a mounting component that houses the piezoelectric element and a cover fixed to the mounting component in a state of accommodating the piezoelectric element, and having a through hole that communicates with the outside to introduce pressure.

[0013] Accordingly, the angle formed by the vibration region in the piezoelectric element is set to 39°–81°. This suppresses the decrease in processability during slit formation and also suppresses the decrease in detection sensitivity.

[0014] Furthermore, according to another aspect of this disclosure, in the method for manufacturing a piezoelectric element, the following steps are performed: forming a piezoelectric film and an electrode film on a support; disposing an etching mask material on the piezoelectric film and the electrode film, and forming an opening on the etching mask material that exposes the portion of the piezoelectric film to be slit; etching the etching mask material as a mask to form a slit that penetrates the piezoelectric film and reaches the support, forming a vibrating region component with a conical portion; and floating the vibrating region component by forming a recess from the side of the support opposite to the piezoelectric film side, forming a vibrating portion having multiple vibrating regions; in the step of forming the slit, a slit with an angle of 39° to 81° is formed.

[0015] Therefore, since the slit forming the vibration region has an angle of 39° to 81°, it is possible to manufacture a piezoelectric element that can suppress the reduction in processability when the slit is formed, thereby suppressing the reduction in detection sensitivity.

[0016] Furthermore, the bracketed reference numerals used to indicate each constituent element, etc., represent an example of the correspondence between that constituent element, etc., and the specific constituent elements, etc., described in the embodiments described later. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of the piezoelectric element according to the first embodiment.

[0018] Figure 2 yes Figure 1 The top view of the piezoelectric element shown.

[0019] Figure 3 yes Figure 1 A schematic diagram of the vibration region shown.

[0020] Figure 4A It means Figure 1 A cross-sectional view showing the manufacturing process of the piezoelectric element.

[0021] Figure 4B It means to continue Figure 4A A cross-sectional view of the manufacturing process of piezoelectric components.

[0022] Figure 4C It means to continue Figure 4B A cross-sectional view of the manufacturing process of piezoelectric components.

[0023] Figure 4D It means to continue Figure 4C A cross-sectional view of the manufacturing process of piezoelectric components.

[0024] Figure 4E It means to continue Figure 4D A cross-sectional view of the manufacturing process of piezoelectric components.

[0025] Figure 5 yes Figure 4D A schematic diagram of the part that forms the slit in the manufacturing process.

[0026] Figure 6 It is a graph showing the relationship between frequency, sensitivity, and effective bandwidth.

[0027] Figure 7 This is a graph showing the relationship between the thickness of the etching mask material and the angle formed relative to the thickness of the piezoelectric film.

[0028] Figure 8 This is a cross-sectional view of the piezoelectric device according to the first embodiment.

[0029] Figure 9A This is a top view of the vibration region in a modified example of the first embodiment.

[0030] Figure 9B This is a top view of the vibration region in a modified example of the first embodiment.

[0031] Figure 9C This is a top view of the vibration region in a modified example of the first embodiment.

[0032] Figure 9D This is a top view of the vibration region in a modified example of the first embodiment.

[0033] Figure 9E This is a top view of the vibration region in a modified example of the first embodiment.

[0034] Figure 9F This is a top view of the vibration region in a modified example of the first embodiment.

[0035] Figure 9G This is a top view of the vibration region in a modified example of the first embodiment.

[0036] Figure 10 This is a schematic diagram of the vibration region in the second embodiment.

[0037] Figure 11 This is a cross-sectional view of the piezoelectric element according to the third embodiment.

[0038] Figure 12 This is a cross-sectional view of the piezoelectric element according to the fourth embodiment.

[0039] Figure 13 This is a cross-sectional view of the piezoelectric element according to the fifth embodiment.

[0040] Figure 14 This is a top view of the piezoelectric element according to the sixth embodiment.

[0041] Figure 15A It is along Figure 14 A cross-sectional view of the XVA-XVA line.

[0042] Figure 15B It is along Figure 14 A cross-sectional view of the XVB-XVB line.

[0043] Figure 16 This is a top view of the electrode film formed in the first region according to the sixth embodiment.

[0044] Figure 17 This is a circuit diagram of the piezoelectric element according to the sixth embodiment.

[0045] Figure 18This is a top view of an electrode film formed in the first region, a modified example of the sixth embodiment.

[0046] Figure 19 This is a circuit diagram of a piezoelectric element according to a modified example of the sixth embodiment.

[0047] Figure 20 This is a top view of the piezoelectric element according to the seventh embodiment.

[0048] Figure 21 This is a top view of the piezoelectric element according to the eighth embodiment.

[0049] Figure 22 This is a top view of the electrode film formed in the first region according to the eighth embodiment.

[0050] Figure 23 This is a circuit diagram of the piezoelectric element according to the eighth embodiment.

[0051] Figure 24 This is a cross-sectional view of the piezoelectric element according to the eighth embodiment.

[0052] Figure 25 This is a top view of a piezoelectric element according to a modified example of the eighth embodiment.

[0053] Figure 26 This is a top view of the electrode film formed in the first region in a modified example of the eighth embodiment.

[0054] Figure 27 This is a circuit diagram of a piezoelectric element according to a modified example of the eighth embodiment.

[0055] Figure 28 This is a cross-sectional schematic diagram of the piezoelectric device according to the ninth embodiment.

[0056] Figure 29 This is a graph showing the relationship between the average slit width, slit length, and acoustic impedance when the thickness of the vibration region is set to constant.

[0057] Figure 30 It is a graph showing the relationship between the thickness of the vibration region, the slit length, and the acoustic impedance when the average slit width is set to constant.

[0058] Figure 31 It is a graph showing the relationship between slit length and acoustic impedance ratio.

[0059] Figure 32 This is a cross-sectional view of the slit of the piezoelectric element according to the tenth embodiment.

[0060] Figure 33 It is a graph showing the relationship between the slit width and acoustic resistance on one side.

[0061] Figure 34This is a top view showing the positional relationship between the piezoelectric element and the connecting member in the eleventh embodiment.

[0062] Figure 35A This is a top view showing the positional relationship between the piezoelectric element and the coupling member in a modified example of the eleventh embodiment.

[0063] Figure 35B This is a top view showing the positional relationship between the piezoelectric element and the coupling member in a modified example of the eleventh embodiment.

[0064] Figure 36A This is a top view showing the positional relationship between the piezoelectric element and the coupling member in a modified example of the eleventh embodiment.

[0065] Figure 36B This is a top view showing the positional relationship between the piezoelectric element and the coupling member in a modified example of the eleventh embodiment.

[0066] Figure 36C This is a top view showing the positional relationship between the piezoelectric element and the coupling member in a modified example of the eleventh embodiment.

[0067] Figure 37 This is a cross-sectional view of the piezoelectric device according to the twelfth embodiment.

[0068] Figure 38 This is a cross-sectional view of a piezoelectric device according to other embodiments. Detailed Implementation

[0069] Hereinafter, embodiments of the present disclosure will be described based on the figures. Furthermore, in the following embodiments, the same or equivalent parts will be labeled with the same reference numerals.

[0070] <First Implementation Method> Reference Figure 1 and Figure 2 The piezoelectric element 1 of the first embodiment will be described. Furthermore, the piezoelectric element 1 of this embodiment is preferably used, for example, as a microphone. Additionally, in Figure 2 In this text, the first electrode section 81 and the second electrode section 82, which will be described later, are omitted. Furthermore, in the following description... Figure 2 In the corresponding figures, the first electrode part 81 and the second electrode part 82 are also appropriately omitted from the representation.

[0071] The piezoelectric element 1 includes a support body 10 and a vibrating part 20, and its planar shape is rectangular. The support body 10 has a support substrate 11 and an insulating film 12. The support substrate 11 has one side 11a and another side 11b, and the insulating film 12 is formed on the support substrate 11. Furthermore, the support substrate 11 is made of, for example, a silicon substrate, and the insulating film 12 is made of, for example, an oxide film.

[0072] The vibrating section 20, which constitutes a sensing section 30 that outputs a pressure detection signal corresponding to sound pressure or other pressure, is disposed on the support body 10. Furthermore, a recess 10a is formed on the support body 10 for floating the inner edge side of the vibrating section 20. Therefore, the vibrating section 20 has a structure having a support region 21a disposed on the support body 10 and a floating region 21b connected to the support region 21a and floating on the recess 10a. In addition, regarding the recess 10a in this embodiment, the shape of its opening end on the vibrating section 20 side (hereinafter also referred to as the opening end of the recess 10a) is set to a planar rectangular shape. Therefore, the floating region 21b is generally set to a planar rectangular shape.

[0073] In this embodiment, the floating region 21b is divided by slits 41 to form four vibration regions 22. In this embodiment, two slits 41 are formed such that they pass through the center C of the floating region 21b and extend to the opposite corners of the floating region 21b. In other words, the slits 41 are formed to extend from each corner of the planar rectangular floating region 21b towards the center C, and the slits 41 intersect at the center C. Thus, the floating region 21b is divided into four vibration regions 22 that are approximately planar triangular in shape. Although there are no particular limitations, in this embodiment, the spacing between the vibration regions 22 (i.e., the average width of the slits 41) is set to about 1 μm. Furthermore, in this embodiment, the slits 41 are formed by anisotropic dry etching as described later.

[0074] Here, the shape of the slit 41 in this embodiment will be described in detail. First, as Figure 1 and Figure 3 As shown, the surface of the vibration region 22 opposite to the support 10 is designated as surface 22a, and the surface of the vibration region 22 on the support 10 side is designated as surface 22b. In this case, the slit 41 is formed as a tapered portion 42 that narrows from surface 22a to surface 22b. In other words, if the surface connecting surface 22a and surface 22b in the vibration region 22 is designated as side surface 22c, then the slit 41 is formed such that side surface 22c becomes a tapered portion 42. Furthermore, the slit 41 in this embodiment is designed such that the slit width g continuously narrows from surface 22a to surface 22b. That is, the slit 41 is formed such that side surface 22c of the vibration region 22 is approximately planar.

[0075] Furthermore, one side 22a and the other side 22b of the vibration region 22 are set to be parallel. Additionally, the slit width g of the slit 41 is, in other words, the spacing between the opposing sides 22c of the vibration region 22. The sides 22c of the vibration region 22 are the surfaces formed by the slit 41.

[0076] Furthermore, the slit 41 is formed such that the angle θ1 formed by the other side 22b and the side 22c in the vibration region 22 (hereinafter also simply referred to as the angle formed by the vibration region 22) is 39° to 81°. In this embodiment, the other side 22b is equivalent to a surface parallel to one side 22a. Additionally, the angle θ1 can also be described as the cone angle of the slit 41. The above describes the shape of the slit 41 in this embodiment.

[0077] Furthermore, regarding each vibration region 22, since the floating region 21b is constructed in a segmented manner as described above, one end 22d forms a fixed end supported by the support body 10 (i.e., the support region 21a), and the other end 22e forms a cantilever as a free end. That is, each vibration region 22 is connected to the support region 21a and is supported by a cantilever.

[0078] The vibrating section 20 is configured to have a piezoelectric film 50 and an electrode film 60 connected to the piezoelectric film 50. Specifically, the piezoelectric film 50 has a lower piezoelectric film 51 and an upper piezoelectric film 52 stacked on the lower piezoelectric film 51. In addition, the electrode film 60 has a lower electrode film 61 disposed below the lower piezoelectric film 51, an intermediate electrode film 62 disposed between the lower piezoelectric film 51 and the upper piezoelectric film 52, and an upper electrode film 63 disposed on the upper piezoelectric film 52. That is, the vibrating section 20 is configured as a dual piezoelectric wafer structure in which the lower piezoelectric film 51 is sandwiched between the lower electrode film 61 and the intermediate electrode film 62, and the upper piezoelectric film 52 is sandwiched between the intermediate electrode film 62 and the upper electrode film 63.

[0079] Furthermore, the vibration unit 20 in this embodiment has a base film 70 on which the lower piezoelectric film 51 and the lower electrode film 61 are disposed. That is, the piezoelectric film 50 and the electrode film 60 are disposed on the support 10 via the base film 70. The base film 70 is not necessarily required, but is provided to facilitate crystal growth when forming the lower piezoelectric film 51, etc.

[0080] The lower piezoelectric film 51 and the upper piezoelectric film 52 are made of ScAlN. The lower electrode film 61, the intermediate electrode film 62, etc., are made of molybdenum, copper, platinum, titanium, aluminum, etc. The base film 70 is made of AlN, etc. In addition, the thickness of the piezoelectric film 50 is set to about thousands of nm, and the thickness of the base film 70 is set to about tens of nm. That is, the base film 70 is extremely thin relative to the piezoelectric film 50.

[0081] Furthermore, regarding each vibration region 22 in this embodiment, its fixed end side is designated as the first region R1, and its free end side is designated as the second region R2. Moreover, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are formed in the first region R1 and the second region R2, respectively. However, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 and the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2 are separated and in an insulating state. Additionally, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 appropriately extend into the support region 21a.

[0082] Furthermore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are formed so as not to reach the slit 41. That is, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are formed to terminate at a position inside the side surface 22c of the vibration region 22. In other words, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are arranged at a position inside the slit 41 in the normal direction with respect to one side surface 22a of the vibration region 22. Therefore, the side surface 22c in the vibration region 22 is composed of the lower piezoelectric film 51, the upper piezoelectric film 52, and the base film 70. Hereinafter, the normal direction with respect to one side surface 22a of the vibration region 22 will be simply referred to as the normal direction. In addition, the so-called normal direction with respect to one side surface 22a of the vibration region 22 can also be referred to as the direction of observation when viewed from the normal direction with respect to one side surface 22a of the vibration region 22.

[0083] In the support region 21a of the vibration section 20, a first electrode portion 81 electrically connected to the lower electrode film 61 and the upper electrode film 63 formed in the first region R1, and a second electrode portion 82 electrically connected to the intermediate electrode film 62 formed in the first region R1 are formed. Furthermore, Figure 1 It is along Figure 2 The cross-sectional view along line II in the figure shows that the vibration region 22 on the left and right sides of the paper have different cross-sections. Additionally, in Figure 2 In the diagram, the first electrode section 81 and the second electrode section 82 are omitted.

[0084] The first electrode portion 81 has a through electrode 81b, which is formed in a hole 81a that penetrates the upper electrode film 63, the upper piezoelectric film 52, and the lower piezoelectric film 51, exposing the lower electrode film 61, and is electrically connected to both the lower electrode film 61 and the upper electrode film 63. Additionally, the first electrode portion 81 has a pad portion 81c formed on and electrically connected to the through electrode 81b. The second electrode portion 82 has a through electrode 82b, which is formed in a hole 82a that penetrates the upper piezoelectric film 52, exposing the intermediate electrode film 62, and is electrically connected to the intermediate electrode film 62. Additionally, the second electrode portion 82 has a pad portion 82c formed on and electrically connected to the through electrode 82b. The first electrode portion 81 and the second electrode portion 82, like the electrode film 60, are constructed using materials such as molybdenum, copper, platinum, titanium, and aluminum.

[0085] Furthermore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2 are not electrically connected to the respective electrode portions 81 and 82, and thus remain in a floating state. Therefore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2 are not necessarily required; in this embodiment, they are provided to protect the portions of the lower piezoelectric film 51 and the upper piezoelectric film 52 located in the second region R2.

[0086] Furthermore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 are separated by slits 41 in each vibration region 22. That is, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 of each vibration region 22 are not formed across each vibration region 22. Moreover, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 of each vibration region 22 are connected via wiring films (not shown).

[0087] Furthermore, in this embodiment, the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 are formed in a manner that is substantially the same as the shape of the vibration region 22, and are thus provided as planar rectangular shapes. However, as described above, the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 are separated by each vibration region 22. Therefore, the shape of the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 here refers to the shape formed by the outline of the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 and the extension lines of those outlines.

[0088] Furthermore, the sensing unit 30 in this embodiment is configured to output a pressure detection signal as a change in charge in the four vibration regions 22. That is, the four vibration regions 22 are electrically connected in series. More specifically, each vibration region 22 is configured as a dual piezoelectric wafer structure, and the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in each vibration region 22 are connected in parallel, and the vibration regions 22 are connected in series.

[0089] The above describes the structure of the piezoelectric element 1 according to this embodiment. With this piezoelectric element 1, if sound pressure is applied to each vibration region 22 (i.e., the sensing section 30), each vibration region 22 vibrates. In this case, for example, if the other end 22e of the vibration region 22 is displaced upwards (i.e., the free end side), tensile stress is generated on the lower piezoelectric film 51, and compressive stress is generated on the upper piezoelectric film 52. Therefore, the sound pressure is detected by extracting this charge from the first electrode section 81 and the second electrode section 82.

[0090] At this time, regarding the stress generated in the vibration region 22 (i.e., the piezoelectric film 50), since the stress is released on the free end side (i.e., the other end 22e side), the stress on the fixed end side is greater than the stress on the free end side. That is, on the free end side, less charge is generated, and the signal-to-noise ratio (SN ratio) tends to decrease. Therefore, in the piezoelectric element 1 of this embodiment, as described above, each vibration region 22 is divided into a first region R1 where stress tends to increase and a second region R2 where stress tends to decrease. Furthermore, in the piezoelectric element 1, the lower electrode film 61, the upper electrode film 63, and the intermediate electrode film 62 disposed in the first region R1 are connected to the first and second electrode portions 81 and 82, and the charge generated on the lower piezoelectric film 51 and the upper piezoelectric film 52 located in the first region R1 is extracted. As a result, the influence of noise can be suppressed.

[0091] Next, refer to Figures 4A-4E , Figure 5 , Figure 6 The manufacturing method of the piezoelectric element 1 described above will be explained.

[0092] First, such as Figure 4A As shown, a structure is prepared to be formed on a support 10 having a support substrate 11 and an insulating film 12, comprising a base film 70, a piezoelectric film 50, an electrode film 60, a first electrode portion 81, and a second electrode portion 82. That is, a structure is prepared without forming... Figure 1 The structure of the recess 10a and slit 41 in the piezoelectric element 1 shown. Furthermore, in Figure 4A The piezoelectric film 50 and electrode film 60 formed in the process are components of the vibrating part 20. Therefore, in Figure 4AThe same reference numerals as those used on one side 22a and the other side 22b of the vibration region 22 are marked in the accompanying drawings. Additionally, the electrode film 60 is adjusted in position so that it does not protrude from the portion where the slit 41 is to be formed.

[0093] Here, the base film 70, piezoelectric film 50, and electrode film 60 are formed by appropriate general sputtering, etching, etc. In this case, when the base film 70 and the lower electrode film 61, which serves as the electrode film 60, are formed on the support 10, because the coefficients of linear expansion of the base film 70 and the lower electrode film 61 are greater than the coefficient of linear expansion of the support 10, the base film 70 and the lower electrode film 61 are formed with residual tensile stress. Therefore, when the piezoelectric film 50 is formed as is, it is easy to form the piezoelectric film 50 with residual tensile stress caused by the tensile stress of the base film 70 and the lower electrode film 61. Moreover, if tensile stress remains on the piezoelectric film 50, it is easy to cause changes in the characteristics of the piezoelectric element 1. Therefore, when forming the piezoelectric film 50, it is preferable to perform the following, for example.

[0094] For example, preferably, when forming the upper piezoelectric film 52, the voltage applied during sputtering is increased compared to when forming the lower piezoelectric film 51, thereby generating compressive stress in the upper piezoelectric film 52. This cancels out the tensile stress of the lower piezoelectric film 51 and the compressive stress of the upper piezoelectric film 52, reducing the residual stress within the piezoelectric film 50 as a whole. In this case, the upper piezoelectric film 52 can also be formed by multiple sputtering operations. Furthermore, tensile stress can be generated in the portion of the upper piezoelectric film 52 on the side of the lower piezoelectric film 51, and compressive stress can be generated in the uppermost portion of the upper piezoelectric film 52 that is opposite to the lower piezoelectric film 51, thereby reducing the residual stress within the piezoelectric film 50.

[0095] Next, as Figure 4B As shown, an etching mask material 200, made of photoresist or the like, is disposed to cover the upper electrode film 63, etc. An opening 201 is formed on the etching mask material 200, and the opening 201 is formed in the part where the slit 41 is to be formed. Hereinafter, the side of the etching mask material 200 that covers the upper electrode film 63 and the upper piezoelectric film 52 is designated as the other side 200b, the side of the etching mask material 200 opposite to the other side 200b is designated as the first side 200a, and the side of the opening 201 is designated as the side side 200c.

[0096] Next, as Figure 4CAs shown, the shape of the opening 201 of the etching mask material 200 is adjusted by heat treatment. Specifically, the etching mask material 200 is configured to cover the upper electrode film 63 and the upper piezoelectric film 52, and the portion on the other side 200b and the portion on the other side 200a, which are fixed to them, shrink differently in a different way. More specifically, during heat treatment, the portion on the other side 200b of the etching mask material 200 is difficult to shrink, while the portion on the other side 200a shrinks easily. Therefore, by heat treatment, the angle θ2 between the other side 200b and the other side 200c of the etching mask material 200 (hereinafter also simply referred to as the angle θ2 of the etching mask material 200) is adjusted according to the angle θ1 formed by the desired vibration region 22. In this case, because the piezoelectric film 50 and the etching mask material 200 are made of different materials, the etching rates during the anisotropic dry etching described later are usually different. Therefore, the angle θ2 formed by the etching mask material 200 is adjusted based on the etching rate, etc., so that the angle θ1 formed by the vibration region 22 becomes the desired value. In addition, since the angle θ2 formed by the etching mask material 200 is adjusted as described above, it may sometimes coincide with the angle θ1 formed by the vibration region 22, but it may sometimes not coincide with the angle θ1 formed by the vibration region 22.

[0097] Next, as Figure 4D As shown, anisotropic dry etching is performed using an etching mask material 200 as a mask to form a slit 41 that penetrates the piezoelectric film 50 and reaches the support body 10. In this embodiment, the slit 41 is formed in such a way that it constitutes four vibration region components 220 having a side surface 22c that forms a cone 42.

[0098] At this time, as described above, the angle θ2 formed by the etching mask material 200 is adjusted according to the angle θ1 formed by the vibration region 22, and the angle θ1 formed by the vibration region constituting portion 220 is set to 39° to 81°. Furthermore, the vibration region constituting portion 220 is a part of the vibration region 22 formed by forming the recess 10a described later. Therefore, the angle θ1 formed by the vibration region constituting portion 220 is the same as the angle θ1 formed by the vibration region 22. Moreover, in the figures, the same reference numerals are used to label one side, the other side, and the side surface of the vibration region constituting portion 220 as those used for one side 22a, the other side 22b, and the side surface 22c of the vibration region 22. Additionally, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are shaped to avoid reaching the slit 41. Therefore, in this process, anisotropic dry etching is performed on the piezoelectric film 50 and the substrate film 70.

[0099] After that, as Figure 4EAs shown, a mask (not shown) is used to etch through the insulating film 12 from the other side 11b of the support substrate 11 to the base film 70, forming a recess 10a. In this embodiment, after removing the support substrate 11 by anisotropic dry etching, the insulating film 12 is removed by isotropic wet etching, forming the recess 10a. Thus, the vibration region constituting portion 220 floats from the support body 10, constituting the vibration region 22, and a vibration region 22 is created. Figure 1 The piezoelectric element 1 shown.

[0100] Furthermore, although not specifically illustrated, in this process, a protective resist covering the upper piezoelectric film 52 and the upper electrode film 63 can be applied to form the recess 10a. This suppresses damage to the vibration region 22 during the formation of the recess 10a. However, the protective resist is removed after the recess 10a is formed.

[0101] Next, the angle θ1 formed by the vibration region constituting portion 220 (i.e., vibration region 22) in the manufacturing process of this embodiment will be explained.

[0102] First, according to the present invention, when performing anisotropic dry etching on a piezoelectric film 50 such as ScAlN, if the formed angle θ1 is 81° or more, the following phenomenon is observed: That is, if the formed angle θ1 is 81° or more, a tendency for reduced processability is observed due to the redeposition of etched atoms on the side surface 22c of the slit 41. Furthermore, according to the present invention, when performing anisotropic dry etching on a piezoelectric film 50 such as ScAlN, if the formed angle θ1 is 63° or more, the following phenomenon is observed: That is, if the formed angle θ1 is 63° or more, a tendency for reduced processability is observed due to the enclosure formed by the redeposition of etched atoms near the opening on the side surface 22a of the slit 41. Therefore, when forming the slit 41, it is preferable to set the formed angle θ1 to 63° or less. This can suppress the reduction in processability caused by enclosures, etc.

[0103] Furthermore, the ScAlN constituting the piezoelectric film 50 is a difficult-to-etch material. Moreover, based on the present inventors' investigation, it has been confirmed that when forming a slit 41 that penetrates the piezoelectric film 50, in order to leave the etching mask material 200 on the piezoelectric film 50, it is preferable to set the thickness of the etching mask material 200 to 3 to 5 times the thickness of the piezoelectric film 50. In other words, it has been confirmed that when forming a slit 41 that penetrates the piezoelectric film 50, in order to prevent the piezoelectric film 50 covered by the etching mask material 200 from being removed by anisotropic dry etching, it is preferable to set the thickness of the etching mask material 200 to 3 to 5 times the thickness of the piezoelectric film 50. That is, as... Figure 5As shown, if the thickness of the piezoelectric film 50 is set to A1 and the thickness of the etching mask material 200 is set to A2, then the thickness A2 of the etching mask material 200 is preferably set to 3A1 to 5A1. Furthermore, as described above, the base film 70 in this embodiment is formed to be extremely thin relative to the piezoelectric film 50. Therefore, the influence of the base film 70 is ignored.

[0104] Furthermore, the formation of slit 41 is also affected by the exposure constraints of the processing apparatus. Based on the inventors' investigation, it has been confirmed that in current general processing apparatuses, such as... Figure 5 As shown, when the width of one side 22a of the slit 41 is defined as the slit width g, the resolution of the slit width g relative to the film thickness A2 of the etching mask material 200 is limited to 1 / 2 to 1 / 3 of the film thickness A2. Therefore, since the film thickness A2 of the etching mask material 200 is expressed as 3A1 to 5A1, the range of 3A1 / 3 to 5A1 / 2 is the limit for the slit width g.

[0105] Furthermore, in the piezoelectric element 1 described above, sound pressure is transmitted from the slit 41. In this case, as... Figure 6 As shown, the longer the effective width of the slit 41, the lower the sensitivity at low frequencies. Therefore, the slit 41 is preferably formed with a narrower effective width. Furthermore, the effective width of the slit 41 refers to the average width of the slit 41. For example, in the case where the slit 41 is set as a cone shape with its width continuously narrowing from one side 22a to the other side 22b, as in this embodiment, the effective width of the slit 41 is the average of the width on the side of one side 22a and the width on the other side 22b.

[0106] Furthermore, since the slit 41 in this embodiment is formed by anisotropic dry etching, the side surface 22c is substantially planar. Therefore, if the width of the other side 22b of the slit 41 is assumed to be approximately 0 in order to suppress sensitivity reduction, the film pressure of the piezoelectric film 50 is set to A1, and the slit width on the side 22a is set to g, then tanθ1 = A1 / (g / 2). Furthermore, g / 2 can also be considered the effective slit width. Therefore, since the slit width g is 3A1 / 3 to 5A1 / 2 as described above, tanθ1 = 2 to 0.8, preferably θ1 = 39° to 63°.

[0107] Furthermore, through further investigation, the inventors confirmed that the film thickness A2 of the etching mask material 200 can also be 1 to 5 times the film thickness A1 of the piezoelectric film 50. That is, it was confirmed that the film thickness A2 of the etching mask material 200 can also be A1 to 5A1. Therefore, in terms of the slit width g, A1 / 3 to 5A1 / 2 is its limit. Therefore, according to the inventors' further investigation, tanθ1 = 6 to 0.8, preferably θ1 = 39° to 81°. Therefore, when forming the slit 41, the angle θ1 formed by the vibration region constituting portion 220 is preferably 39° to 81°. As a result, the reduction in the processability of the slit 41 due to the film thickness A2 of the etching mask material 200 can be suppressed.

[0108] Furthermore, if we summarize the relationship between the ratio of the film thickness A2 of the etching mask material 200 to the film thickness A1 of the piezoelectric film 50 (hereinafter also referred to as the film thickness ratio) and the angle formed, then as follows: Figure 7 As shown. Moreover, as mentioned above, the resolution of the slit width g relative to the film thickness A2 of the etching mask material 200 is limited to 1 / 2 to 1 / 3 of the film thickness A2. Therefore, the lower limit of the angle θ1, i.e., 39°, is the case where the resolution is 1 / 2 times that of the etching mask material 200, and the upper limit is the case where the resolution is 1 / 3 times that of the etching mask material.

[0109] Here, as a comparative example of piezoelectric element 1, an example can be a piezoelectric element in which an easily etchable material such as AlN is used for the piezoelectric film 50 and the side 22c of the vibration region 22 is approximately perpendicular to the other side 22b. Furthermore, the effective width of the slit 41 in the comparative example piezoelectric element 1 is set to g. In this case, if the effective width in the piezoelectric element 1 of this embodiment is g or more, the width of the slit 41 becomes wider, and therefore, the sensitivity may be reduced compared to the comparative example piezoelectric element 1.

[0110] Therefore, the slit 41 is preferably formed in a manner that is less than or equal to the effective width of the slit 41 in the piezoelectric element 1, which is a comparative example of effective width. That is, it is preferably configured such that tanθ1 is 1 or more. Therefore, θ1 is preferably set to 45° or more, and more preferably to 45° to 81°. This also helps to suppress the reduction in sensitivity. In this case, by setting θ1 to 63° or less, it is also possible to suppress the reduction in the processability of the slit 41 due to barriers, etc.

[0111] Next, the piezoelectric device S10 using the piezoelectric element 1 described above will be explained.

[0112] like Figure 8As shown, the piezoelectric device S10 of this embodiment is configured to house the piezoelectric element 1 within a housing 100. The housing 100 has a printed circuit board 101 and a cover 102. The printed circuit board 101 mounts the piezoelectric element 1 and a circuit board 110 for performing predetermined signal processing, etc. The cover 102 is fixed to the printed circuit board 101 to accommodate the piezoelectric element 1 and the circuit board 110. Furthermore, in this embodiment, the printed circuit board 101 corresponds to the mounted component.

[0113] Although not specifically illustrated, the printed circuit board 101 is configured to have wiring portions, through-hole electrodes, etc., and may also be equipped with electronic devices such as capacitors (not shown) as needed. Regarding the piezoelectric element 1, the other side 11b of the support substrate 11 is mounted on one side 101a of the printed circuit board 101 via bonding members 2 such as adhesives. The circuit board 110 is mounted on one side 101a of the printed circuit board 101 via bonding members 111 made of conductive components. Furthermore, the pad portion 82c of the piezoelectric element 1 and the circuit board 110 are electrically connected via bonding wires 120. Additionally, the pad portion 81c of the piezoelectric element 1 is connected to... Figure 8 Different cross sections are electrically connected to the circuit board 110 via bonding lines 120. The cover 102 is made of metal, plastic or resin, etc., and is fixed to the printed circuit board 101 by bonding members such as adhesives (not shown) in a manner that accommodates the piezoelectric element 1 and the circuit board 110.

[0114] Furthermore, in this embodiment, a through hole 101b is formed in the portion of the printed circuit board 101 opposite to the sensing unit 30. Specifically, the through hole 101b is configured to be approximately cylindrical, and its central axis is aligned with the center portion C in the vibration region 22 in the normal direction.

[0115] The above describes the structure of the piezoelectric device S10 according to this embodiment. Hereinafter, within the housing 100, the space between the portion forming the through hole 101b and the vibration region 22 is designated as the pressure-bearing surface space S1. Furthermore, the space that is continuous with the pressure-bearing surface space S1 without passing through the slit 41, including the space located on the side opposite to the pressure-bearing surface space S1 across the vibration region 22, is designated as the rear space S2. In addition, the rear space S2 can be considered a space different from the pressure-bearing surface space S1 within the housing 100, or it can be considered a space other than the pressure-bearing surface space S1. In other words, the pressure-bearing surface space S1 can also be considered a space that influences the surface of the vibration region 22 formed on the side of the through hole 101b of the housing 100 (i.e., the other surface 22b in this embodiment). The rear space S2 can also be considered a space that influences the surface of the vibration region 22 formed on the side opposite to the side of the through hole 101b of the housing 100 (i.e., one surface 22a in this embodiment).

[0116] Furthermore, in such a piezoelectric device S10, sound pressure is applied to the vibration region 22 (i.e., the sensing unit 30) by introducing sound pressure as pressure into the pressure surface space S1, and the sound pressure is detected as described above.

[0117] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39° to 81°. Therefore, the reduction in processability of the slit 41 due to the film thickness A2 of the etching mask material 200 can be suppressed, and the slit 41 can be appropriately formed. In addition, since the angle θ1 is 81° or less, the effect of redeposition can be reduced, and the reduction in processability can be suppressed.

[0118] (1) In this embodiment, by setting the angle θ formed by the vibration zone 22 to 63° or less, it is possible to suppress the reduction in processability due to the influence of the fence.

[0119] (2) In this embodiment, by setting the angle θ1 formed by the vibration region 22 to 45° or more, the decrease in sensitivity can be suppressed.

[0120] <Modifications of the first embodiment described above> A variation of the first embodiment described above will be explained. In the first embodiment, when the slit 41 is formed, dry etching can also be performed after wet etching. Accordingly, the etching mask material 200 is not removed during wet etching. Therefore, the film thickness A2 of the etching mask material 200, which is defined by the film thickness A1 of the piezoelectric film 50, can be reduced, and the slit width g, which is defined by the film thickness A2 of the etching mask material 200, can be narrowed. Therefore, the effective width g / 2 can be narrowed, and the sensitivity can be improved.

[0121] Furthermore, in the first embodiment described above, the planar shape of the vibration region 22 can be appropriately modified. For example, as... Figures 9A to 9G As shown, the planar shape of the vibration region 22 is set to a hexagonal, octagonal, decagonal, dodecagonal, fourteen-sided, sixteen-sided, or circular shape. Additionally, although not specifically illustrated, the vibration region 22 can also be set to other polygonal shapes. Furthermore, in Figures 9A to 9G In the original text, the slit 41 formed in the vibration region 22 is omitted, but slits 41 are formed in the vibration region 22. For example, in... Figure 9A When the planar shape of the vibration region 22 is hexagonal, the slits 41 are formed from the corners of the outer shape of the vibration region 22, intersecting at the center C. Furthermore, in the case where... Figure 9G In the case where the planar shape of the vibration region 22 is circular, the slits 41 are formed in a manner that intersects at the center and are evenly distributed circumferentially as desired.

[0122] <Second Implementation Method> The second embodiment will be described. This embodiment differs from the first embodiment in that the shape of the slit 41 is changed. Other aspects are the same as in the first embodiment, and therefore will not be described here.

[0123] In the piezoelectric element 1 of this embodiment, such as Figure 10 As shown, the slit 41 is formed with a conical cone 42 on one side 22a and a constant width portion 43 on the other side 22b. That is, the slit 41 is formed with a constant width portion 43 on the other side 22b, where the side surface 22c is perpendicular to the other side 22b. Furthermore, the slit 41 is configured as a structure where the cone 42 and the constant width portion 43 are connected. In this embodiment, the angle θ1 between the cone 42 and the imaginary surface Sv parallel to one side 22a is set to 39° to 81°.

[0124] Furthermore, such a slit 41 can be formed, for example, by removing the etching mask material 200 after forming the cone portion 42, configuring another etching mask material, and performing anisotropic dry etching to form the constant portion 43. In addition, regarding the opening formed in the other etching mask material when forming the constant portion 43, the angle between the side of the opening and the other side of the etching mask material is set to approximately 90°.

[0125] According to the above-described embodiment, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0126] (1) In this embodiment, the slit 41 is formed with a cone-shaped cone portion 42 and a constant portion 43 with a constant width. Therefore, for example, compared with a piezoelectric element 1 having the same width on both the side 22a and the side 22b of the slit 41, the piezoelectric element 1 of this embodiment can narrow its effective width. Therefore, sound pressure is difficult to transmit, and the sensitivity can be improved.

[0127] <Third Implementation Method> The third embodiment will be described. In this embodiment, the shape of the boundary portion between the recess 10a and the vibrating portion 20 is changed compared to the first embodiment. Other aspects are the same as in the first embodiment, and therefore will not be described here.

[0128] The piezoelectric element 1 in this embodiment is as follows: Figure 11As shown, the opening end of the recess 10a and the boundary portion B of the vibrating portion 20 are configured as curved shapes. In this embodiment, the recess 10a is formed such that its opening end reaches the base film 70, and the boundary portion B of the base film 70 with the recess 10a is configured as curved. Furthermore, such a curved shape is formed, for example, by removing a portion of the base film 70 using isotropic wet etching during the removal of the insulating film 12.

[0129] According to the above-described embodiment, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0130] (1) In this embodiment, the boundary portion B of the recess 10a and the vibrating portion 20 is set to a curved shape. Therefore, it is possible to suppress stress concentration in the boundary portion B of the recess 10a and the vibrating portion 20 when sound pressure is applied to the vibrating region 22, and it is possible to suppress the damage to the vibrating region 22.

[0131] <Fourth Implementation Method> The fourth embodiment will be described. In this embodiment, a high-strength material is disposed within the base membrane 70, compared to the third embodiment. Other aspects are the same as in the third embodiment and therefore will not be described here.

[0132] like Figure 12 As shown, in this embodiment, the piezoelectric element 1 has a protective member 71 made of a material with higher strength than the base film 70 at the boundary portion B between the base film 70 and the recess 10a. The protective member 71 is made of, for example, a nitride film.

[0133] According to the above-described embodiment, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0134] (1) In this embodiment, a protective member 71 is provided at the boundary portion B of the basement membrane 70 with the recess 10a. That is, the protective member 71 is provided at the portion where stress is easily concentrated when sound pressure is applied to the vibration region 22. Therefore, it is possible to suppress the vibration region 22 from being damaged when sound pressure is applied to the vibration region 22.

[0135] <Fifth Implementation Method> The fifth embodiment will be described. This embodiment combines the third and fourth embodiments. Other aspects are the same as in the third embodiment, and therefore will not be described here.

[0136] like Figure 13As shown, in this embodiment, the piezoelectric element 1 has a protective member 71 disposed at the boundary portion B of the base film 70 with the recess 10a. Furthermore, the boundary portion B of the protective member 71 with the recess 10a is designed to be curved.

[0137] According to the above-described embodiment, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0138] (1) In this embodiment, a protective member 71 is disposed at the boundary portion B of the basement membrane 70 with the recess 10a. Furthermore, the boundary portion B of the protective member 71 with the recess 10a is made into a curved shape. Therefore, it is possible to further suppress the damage to the vibration region 22.

[0139] <Sixth Implementation Method> The sixth embodiment will be described. This embodiment differs from the first embodiment in that the arrangement of the first electrode portion 81 and the second electrode portion 82 is changed. Other aspects are the same as in the first embodiment and will therefore be omitted here.

[0140] Regarding the piezoelectric element 1 in this embodiment, as follows: Figure 14 As shown, its planar structure is the same as that of the first embodiment described above. Furthermore, in this embodiment, as... Figure 14 As shown, regarding the four vibration regions 22, one vibration region 22 is designated as the first vibration region 221, and the second to fourth vibration regions 222 to 224 are designated along the circumferential direction starting from the first vibration region 221.

[0141] Moreover, such as Figure 15A As shown, the first electrode portion 81 is connected to the lower electrode film 61 and the upper electrode film 63 formed in the first vibration region 221. Figure 15B As shown, the second electrode portion 82 is connected to the intermediate electrode film 62 formed in the fourth vibration region 224.

[0142] In addition, such as Figure 16 As shown, the electrode film 60 of this embodiment is formed such that the shape of the portion formed in the first region R1 is approximately the same as the shape of the vibration region 22, and is set to a planar rectangular shape in this embodiment. However, the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 are separated by the first to fourth vibration regions 221 to 224 as described above. Therefore, the shape of the portion of the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 formed in the first region R1 refers to the shape formed by the outline of the portion of the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63 located in the first region R1 and the extension line of that outline. In addition, although in Figure 17The middle layer is shown as electrode film 60, and the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63, which are electrode films 60, are respectively set in the first region R1 to be the same as the electrode film 60. Figure 17 The electrode film 60 has the same shape.

[0143] Moreover, in this embodiment, such as Figure 17 As shown, this becomes a circuit structure that connects each vibration region 221 to 224 in series.

[0144] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0145] (1) In this embodiment, the first to fourth vibration regions 221 to 224 are connected in series. Therefore, it is easy to wind the wiring portion of the electrode film 60 that connects each vibration region 221 to 224.

[0146] <Modifications of the Sixth Embodiment> A variation of the sixth embodiment will be described. In the piezoelectric element 1 of this embodiment, as shown... Figure 18 As shown, the electrode film 60 can also be divided into multiple charge regions 60a in the first region R1. For example, the electrode film 60 can also be divided into three charge regions 60a in the first region R1 of each vibration region 221 to 224. Furthermore, the lower electrode film 61, the middle electrode film 62, and the upper electrode film 63, which are the electrode film 60, are respectively divided into three charge regions 60a in the first region R1. Figure 18 That is, it is divided into charge regions 60a. In this case, as... Figure 19 As shown, the piezoelectric element 1 is configured such that the capacitors formed by the divided charge regions 60a are connected in series. This reduces the capacitance within each vibration region 221-224, thereby increasing the output. In other words, it improves the detection sensitivity.

[0147] <Seventh Implementation Method> The seventh embodiment will be described. This embodiment differs from the first embodiment in that the shape of the slit 41 is changed. Other aspects are the same as in the first embodiment, and therefore will not be described here.

[0148] Regarding the piezoelectric element 1 in this embodiment, as follows: Figure 20 As shown, the slit 41 is configured in the normal direction as a cone shape with a slit width g that narrows from the support region 21a side toward the center C of the floating region 21b. In other words, the slit 41 is configured in the normal direction as a cone shape with a slit width g that narrows from the support region 21a side toward the other end 22e side of the vibration region 22.

[0149] According to the above-described embodiment, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0150] (1) In this embodiment, the slit 41 is configured as a cone shape in which the slit width g narrows toward the center C of the floating region 21b. Therefore, when sound pressure is applied to the vibration region 22 and the vibration region 22 flexes, the slit width g of each slit 41 in the flexed state is easily uniformized. In other words, when the vibration region 22 flexes, for each slit 41, the portion of the slit width g on the support region 21a side and the portion on the center C side in the normal direction are easily uniformized. Therefore, the ease of sound pressure transmission in each slit 41 is less likely to vary, and noise can be reduced. Therefore, the detection accuracy can be further improved.

[0151] <Eighth Implementation Method> In this embodiment, the shapes of the vibration region 22 and the intermediate electrode film 62 are adjusted compared to the first embodiment. Other aspects are the same as in the first embodiment and therefore are omitted here.

[0152] Reference Figure 21 and Figure 22 The piezoelectric element 1 of this embodiment will be described. Furthermore, in Figure 21 In this text, slit 41 is omitted. However, slit 41 is actually provided in the same way as in the first embodiment described above, extending from each corner of the planar shape of the vibration region 22 toward the center C.

[0153] Regarding vibration region 22, such as Figure 21 As shown, its shape is set to a regular octagon in the normal direction. That is, the shape of the opening of the recess 10a of the support 10 is set to a regular octagon. Hereinafter, the reason for setting the vibration region 22 to a regular octagon shape will be explained. As described above, in this embodiment, the support substrate 11 is made of silicon. Therefore, by setting the shape of the opening of the recess 10a (i.e., the shape of the vibration region 22) to a regular octagon, it is possible to suppress the localized deformation concentration at the opening end of the recess 10a in the support substrate 11 (i.e., the outer end of the vibration region 22). Therefore, it is possible to suppress the localized deformation concentration at the boundary between the vibration region 22 and the support region 21a.

[0154] Furthermore, regarding the electrode film 60 of this embodiment, as... Figure 22As shown, in the normal direction, the portion of the electrode film 60 formed in the first region R1 has an octagonal shape. That is, the outer edge of the electrode film 60 in the first region is formed in a manner that is approximately aligned with the opening end of the recess 10a. Furthermore, the portion of the electrode film 60 formed in the first region R1 is separated from the electrode film slit 60b by a slit 60b, which is different from the slit 41. Specifically, six electrode film slits 60b are formed, and the electrode film slits 60b are formed in a hexagonal shape, forming an imaginary shape (hereinafter also simply referred to as the imaginary shape) KS that connects a predetermined portion within each electrode film slit 60b. More specifically, the electrode film slits 60b are formed in a hexagonal shape, forming an imaginary shape that connects the portion where the outer shapes of each electrode film slit 60b and the electrode film 60 intersect.

[0155] Furthermore, the shape of the portion of the electrode film 60 located in the first region R1, as described above, refers to the shape formed by the outline of the portion of the electrode film 60 located in the first region R1 and the extension of that outline.

[0156] The reason for setting the imaginary shape KS of the electrode film 60 to a hexagonal shape will be explained below. As described above, the electrode film 60 and the piezoelectric film 50 are stacked in the order of lower electrode film 61, lower piezoelectric film 51, intermediate electrode film 62, upper piezoelectric film 52, and upper electrode film 63. Moreover, when forming the lower electrode film 61, intermediate electrode film 62, and upper electrode film 63, after the metal film is formed, the metal film is patterned according to the desired shape by using dry etching or the like with a mask. At this time, although a mask is used, the lower piezoelectric film 51 and the upper piezoelectric film 52, which serve as the substrate, may be etched. In this case, since the piezoelectric film 50 is formed using ScAlN and has a hexagonal crystal structure, by setting the imaginary shape KS of the electrode film 60 to a hexagonal shape, it is possible to suppress the deterioration of the crystallinity of the piezoelectric film 50 when etching the surface of the piezoelectric film 50. That is, by matching the portion of the slit 60b used to form the electrode film with the crystal structure of the piezoelectric film 50, it is possible to suppress the characteristic variation of the piezoelectric film 50.

[0157] Moreover, such as Figure 23 As shown, the piezoelectric element 1 of this embodiment connects the capacitances between the electrode films 61 to 63. In this embodiment, as described above, the electrode film 60 is divided into six parts by a slit 60b, which is different from the electrode film 41. Therefore, the piezoelectric element 1 of this embodiment has six regions 226 divided into six parts, and outputs a pressure detection signal based on the capacitance of each region 226.

[0158] Furthermore, in this embodiment, the electrode film 60 is separated from the electrode film by the slit 60b as described above, but not by the slit 41. Therefore, as... Figure 24The electrode films 60 are connected at the portion forming the slit 41. Such a piezoelectric element 1 is, for example, used in... Figure 4A and Figure 4B The process involves forming slits 41 or electrode film slits 60b during the formation of each film. For example, after forming the base film 70, a metal film is formed on the base film 70. Then, the electrode film slits 60b are formed when the metal film is patterned to form the lower electrode film 61. Next, a lower piezoelectric film 51 is formed on the lower electrode film 61. Before forming the intermediate electrode film 62, a slit 41 penetrating only the lower piezoelectric film 51 can be formed on the lower piezoelectric film 51. Then, the piezoelectric element 1 of this embodiment is manufactured by similarly forming the intermediate electrode film 62, the upper piezoelectric film 52, and the upper electrode film 63.

[0159] Furthermore, regarding the electrode film 60 of this embodiment, the outer edge end on the side opposite to the center portion C is actually formed to the outside of the first region R1, and the inner edge end is formed to the inside of the second region R2. Therefore, when the metal film is patterned according to the desired shape after the metal film is formed to form the intermediate electrode film 62 and the upper electrode film 63, even if the piezoelectric film 50 is removed in the portion different from the electrode film slit 60b, the piezoelectric film 50 outside the first region R1 will not be removed. Therefore, by setting the imaginary shape KS to a hexagonal shape, it is possible to suppress the reduction in detection accuracy.

[0160] Furthermore, the imaginary shape KS of the vibration region 22 and the electrode film 60 is configured to be point-symmetric with respect to the center portion C. In this embodiment, the imaginary shape KS of the electrode film 60 is hexagonal in the normal direction, and the outer shape of the vibration region 22 is regular octagonal. Moreover, the vibration region 22 and the electrode film 60 are arranged such that two opposite vertices in the imaginary shape KS of the electrode film 60 coincide with two opposite vertices in the outer shape of the vibration region 22. In other words, two opposite vertices in the imaginary shape KS of the electrode film 60 are arranged on the imaginary line K1 connecting the two opposite vertices in the vibration region 22.

[0161] Furthermore, the piezoelectric element 1 (i.e., the vibrating part 20) in this embodiment is set to a planar rectangular shape as described above. Moreover, the imaginary shape KS of the vibrating region 22 and the electrode film 60 is formed such that each corner is located on a different part of the imaginary line K2 that connects the opposite corners in the shape of the piezoelectric element 1.

[0162] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0163] (1) In this embodiment, the vibration region 22 and the electrode film 60 are configured to be symmetrical about the center C in the normal direction. Therefore, when sound pressure is applied to the vibration region 22, charge can be easily and evenly extracted from the electrode film 60. Therefore, the decrease in detection sensitivity can be suppressed, and the decrease in detection accuracy can be suppressed.

[0164] (2) In this embodiment, the imaginary shape KS of the vibration region 22 and the electrode film 60 is formed such that each corner is located on a different part of the imaginary line K2 that connects the opposite corners in the shape of the piezoelectric element 1. Therefore, it is possible to suppress the decrease in detection accuracy. That is, in the piezoelectric element 1, the part located on the imaginary line K2 that connects the opposite corners is prone to deformation due to thermal stress, etc. In this case, if the corner of the vibration region 22 or the corner of the imaginary shape KS of the electrode film 60 is located on the imaginary line K2, it is easy to apply large thermal stress to the easily deformable corner, and the noise is likely to increase. Therefore, by making the corners of the vibration region 22 and the electrode film 60 located on a different part from the imaginary line K2 as in this embodiment, it is possible to suppress the decrease in detection accuracy.

[0165] (3) In this embodiment, the imaginary shape KS of the electrode film 60 is set to a hexagonal shape. Therefore, it is possible to suppress the deterioration of the crystallinity of the piezoelectric film 50 when the electrode film 60 is patterned and constructed. Therefore, it is possible to suppress the variation of the characteristics of the piezoelectric element 1.

[0166] (4) In this embodiment, the shape of the vibration region 22 is set to a regular octagon. Therefore, it is possible to suppress the concentration of deformation in local parts of the vibration region 22.

[0167] <Modifications of the Eighth Embodiment> A variation of the eighth embodiment described above will be described. In the eighth embodiment, if the vibration region 22 and the electrode film 60 are configured to be symmetrical about the center portion C, then, as in the eighth embodiment, it is easy to extract charge evenly from the electrode film 60. Therefore, for example, as... Figure 25 As shown, the vibration region 22 and the electrode film 60 can also be arranged such that a pair of opposite vertices in the electrode film 60 are located on an imaginary line K3 connecting the centers of a pair of opposite sides and the center portion C in the vibration region 22. Furthermore, in this configuration, the vibration region 22 and the electrode film 60 are preferably formed such that each corner is located at a different point from the imaginary line K2. Additionally, in Figure 25 In, with Figure 21 Similarly, the illustration of slit 41 is omitted.

[0168] Furthermore, in the eighth embodiment described above, similar to the variation of the sixth embodiment, the electrode film 60 can also be as follows: Figure 26As shown, the first region R1 is divided into multiple charge regions 60a. Furthermore, as... Figure 27 As shown, the segmented charge regions 60a can also be connected in series. Furthermore, in the case of the electrode film 60 being configured in this way, the electrode film 60 can also be segmented using the slit 41 formed in the piezoelectric film 50.

[0169] <Ninth Implementation Method> The ninth embodiment will be described. This embodiment specifies the slit length, etc., compared to the first embodiment. Other aspects are the same as in the first embodiment, so descriptions are omitted here.

[0170] The piezoelectric device S10 in this embodiment is basically the same as that in the first embodiment, such as... Figure 28 It is constructed as shown. Furthermore... Figure 28 The acoustic impedance Rg, etc., described later, are schematically shown. In this case, if the acoustic compliance of the piezoelectric element 1 is set as Cm and the acoustic compliance of the rear space S2 is set as Cb, then the sensitivity of the piezoelectric device S10 is represented by 1 / {(1 / Cm) + (1 / Cb)}. Furthermore, the acoustic compliance Cb is represented by the following formula 1.

[0171] [Equation 1] In Equation 1 above, Vb is the volume of the rear space S2, ρ0 is the air density, and c is the speed of sound. Furthermore, the acoustic compliance Cb is proportional to the volume Vb of the rear space S2. Therefore, the smaller the rear space S2, the smaller the influence of the acoustic compliance Cb on the sensitivity. Moreover, currently, miniaturization of the piezoelectric device S10 is desired; by achieving miniaturization of the piezoelectric device S10, the rear space S2 also becomes smaller. Therefore, in terms of the sensitivity of the piezoelectric device S10, the acoustic compliance Cm of the piezoelectric element 1 has a significant impact.

[0172] Here, in the piezoelectric element 1 described above, it is desirable to broaden the frequency range that can maintain sensitivity. Therefore, in this embodiment, the low-frequency attenuation frequency is reduced.

[0173] First, if the acoustic resistance (i.e., air resistance) based on slit 41 is set as Rg, then the low-frequency attenuation frequency fr is represented by the following formula 2.

[0174] [Equation 2] Therefore, to reduce the low-frequency attenuation frequency fr, it is only necessary to increase the acoustic impedance Rg or the acoustic compliance Cb of the rear space S2. However, as shown in Equation 1 above, the acoustic compliance Cb is proportional to the volume Vb of the rear space S2. Moreover, miniaturization of the piezoelectric device S10 is currently desired. Therefore, to reduce the low-frequency attenuation frequency fr, it is preferable to increase the acoustic impedance Rg. Furthermore, the acoustic impedance Rg is expressed by Equation 3 below.

[0175] [Equation 3] In the above formula 3, μ is the air frictional resistance, h is the thickness of the vibration region 22, ga is the average slit width ga of the slit 41, and L is the slit length L of the slit 41 in each vibration region 22. Furthermore, the average slit width ga refers to the average width of the slit 41 along the thickness direction. Additionally, as... Figure 2 As shown, the slit length L refers to the length of the slit 41 along the extending direction, which is the length from the corner of the vibration region 22 to the center C. In other words, the slit length L refers to the length of the slit 41 along the side 22c of the vibration region 22 in a direction orthogonal to the thickness direction, which is the length of the slit 41 along the side 22c of the vibration region 22.

[0176] Furthermore, in order to set the low-frequency attenuation frequency fr to be below 20Hz outside the hearing range, it is sufficient to satisfy the following formula 4.

[0177] [Equation 4] In this case, if equation 4 is changed, it becomes equation 5 as follows. Moreover, if equation 5 is changed based on equation 3, it becomes equation 6 as follows.

[0178] [Equation 5] [Equation 6] Therefore, in order to set the low-frequency attenuation frequency fr to below 20Hz, it is sufficient to form the structure such that the slit length L, the average slit width ga, the thickness h of the vibration region 22, and the acoustic compliance Cb of the rear space S2 satisfy the above formula 6. Moreover, in this embodiment, the slit length L, etc., are adjusted to satisfy the above formula 6.

[0179] Here, for example, if the thickness h of the vibration region 22 is set to 1 μm, such as Figure 29 As shown, it can be confirmed that the acoustic impedance Rg decreases with increasing average slit width ga and also with increasing slit length L. Furthermore, when the average slit width ga is set to 1 μm, as... Figure 30 As shown, it can be confirmed that the acoustic impedance Rg decreases with increasing thickness h of the vibrating region 22, and also decreases with increasing slit length L. Furthermore, as... Figure 31 As shown, for example, if we take the case where the slit length L is 700 μm and the acoustic impedance is around 100 Hz as a reference, we can confirm that if the slit length L is around 150 μm, the acoustic impedance can be reduced to below 20 Hz.

[0180] In addition, Figure 31 In this case, since the slit length L is 700 μm as the baseline, the acoustic impedance ratio is 1 when the slit length L is 700 μm. Additionally, Figure 31 In this context, the volume of the rear space S2, which affects the acoustic compliance Cb, is set to 4 × 10⁻⁶. －9 m 3 .

[0181] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0182] (1) In this embodiment, the slit length L, the average slit width ga, the thickness h of the vibration region 22, and the acoustic compliance Cb of the rear space S2 are formed to satisfy the above formula 6. Therefore, the low-frequency attenuation frequency fr can be set to 20Hz or less, and the range of maintainable sensitivity can be widened.

[0183] <Tenth Implementation Method> The tenth embodiment will be described. This embodiment differs from the ninth embodiment in that the shape of the slit 41 is changed. Other aspects are the same as in the ninth embodiment, and therefore will not be described here.

[0184] In the ninth embodiment described above, a conical structure in which the slit width g gradually narrows along the thickness direction of the vibration region 22 was described. However, regarding the slit 41, the slit width g can also vary stepwise along the thickness direction of the vibration region 22, for example, as shown below. Figure 32 As shown, the slit width g can also be configured to vary in three steps. Specifically, in this embodiment, the slit 41 is formed such that the slit width g widens in the order of g1, g2, and g3 from the other side 22b of the vibration region 22 towards the other side 22a. Furthermore, in this structure, the angle between the line connecting the opening end of the slit 41 on the other side 22b and the opening end of the slit 41 on the other side 22a and the other side 22b is the angle θ1 formed.

[0185] In this case, the slit length L can be calculated using the average slit width ga, but it can also be calculated using the following formula 7. Furthermore, in the following formula 7, in the vibration region 22, the thickness of the portion with slit width g1 is set as the thickness h1 of the vibration region 22, the thickness of the portion with slit width g2 is set as the thickness h2 of the vibration region 22, and the thickness of the portion with slit width g3 is set as the thickness h3 of the vibration region 22.

[0186] [Equation 7] Furthermore, regarding slit 41, if the width of the other side 22b is set to g1 and the width of the side 22a is set to g3, then if the order of change between the other side 22b and the side 22a is changed, the acoustic impedance Rg will be as follows: Figure 33 As shown. Specifically, it can be confirmed that when the slit width g1 on the other side 22b and the slit width g3 on the other side 22a are the same, the acoustic impedance Rg tends to increase when the change order is smaller. Moreover, according to the above formula 2, the low-frequency attenuation frequency fr decreases when the acoustic impedance Rg is larger. Therefore, when the slit width g of the slit 41 is varied along the thickness direction of the vibration region 22, it is preferable to consider the acoustic compliance Cb of the rear space S2 when adjusting the order. Furthermore, Figure 33 The figure shows the case where the slit width g1 on the other side 22b is set to 0.8μm and the overall thickness h of the vibration region 22 is set to 1μm, while the slit width g3 on the other side 22a is changed.

[0187] According to the above-described embodiment, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0188] (1) In this embodiment, the slit length L, the average slit width ga, the thickness h of the vibration region 22, and the acoustic compliance Cb of the rear space S2 are formed to satisfy the above formula 7. Therefore, the low-frequency attenuation frequency fr can be set to 20Hz or less, and the range of maintainable sensitivity can be widened.

[0189] <Eleventh Implementation Method> The eleventh embodiment will be described. This embodiment specifies the shape of the joining member 2 relative to the first embodiment. Other aspects are the same as in the first embodiment, and therefore will be omitted here.

[0190] In the piezoelectric device S10 of this embodiment, such as Figure 34 As shown, the joining member 2 is configured in a rectangular shape with corners in the normal direction. Furthermore, the joining member 2 is joined to a portion on the other side 11b of the support substrate 11 in the piezoelectric element 1 that is different from the portion forming the corner of the piezoelectric element 1. In this embodiment, the joining member 2 is arranged in the normal direction such that each corner of the joining member 2 protrudes from the respective opposite edges of the piezoelectric element 1. Additionally, the joining member 2 is arranged such that the corners of the joining member 2 are located at portions different from those on the imaginary line K2 connecting the opposite corners in the shape of the piezoelectric element 1. Furthermore, the joining member 2 in this embodiment is constructed using a joining piece with a predefined shape.

[0191] Furthermore, the electrode film 60 and vibration region 22 in this embodiment are the same as those in the eighth embodiment described above, with the electrode film 60 being hexagonal and the vibration region 22 being octagonal. Moreover, the electrode film 60 and vibration region 22 are arranged symmetrically about the center C. In addition, in Figure 34 In the text, slit 41 is omitted from the representation.

[0192] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0193] (1) In this embodiment, the bonding member 2 is disposed in a portion of the piezoelectric element 1 that differs from the corner of its outer shape. Therefore, the propagation of thermal stress from the printed circuit board 101 to the corner of the piezoelectric element 1, where deformation is prone to increase, can be suppressed. As a result, the piezoelectric element 1 is less likely to deform due to the propagated thermal stress, and the vibration region 22 is less likely to deform. Thus, the decrease in detection sensitivity can be suppressed, and the detection accuracy can be improved.

[0194] (2) In this embodiment, the joining member 2 is provided with a rectangular shape having corners. Moreover, the joining member 2 is arranged in the normal direction such that the corners are located at a different part from the imaginary line K2. Therefore, it is possible to suppress the concentration of stress at the corners of the joining member 2 due to the deformation of the piezoelectric element 1, and to suppress defects such as peeling of the joining member 2.

[0195] <Variations on the Eleventh Embodiment> A variation of the eleventh embodiment described above will be described. The joining member 2 can be as follows: Figure 35A As shown, it is set to an equilateral triangle shape in the normal direction, or it can be like... Figure 35B The shape shown is a regular octagon in the normal direction. However, although not specifically illustrated, the connecting member 2 can also be a regular hexagon, a regular decagon, or the like in the normal direction. Furthermore, the connecting member 2 can be configured to protrude from the piezoelectric element 1 in the normal direction, or it can be configured only inside the piezoelectric element 1.

[0196] Alternatively, the bonding member 2 can also be based on the through hole 101b formed on the printed circuit board 101, such as... Figures 36A-36C Configured as shown. Furthermore... Figures 36A-36C This is a top view of the piezoelectric element 1 and the connecting member 2, viewed from the other side 11b of the support substrate 11. Additionally, in Figures 36A-36C In the diagram, the vibration region 22 is omitted, and the portion opposite to the through hole 101b is represented by a dashed line. Furthermore, in... Figures 36A-36C In the support substrate 11, the recess 10a is formed in a shape that is consistent with the through hole 101b in the normal direction.

[0197] For example, such as Figure 36A As shown, the joining member 2 can also be configured as an annular shape surrounding the through hole 101b in the normal direction. Additionally, as... Figure 36B As shown, the joining member 2 can also be configured in a "+" shape in the normal direction, extending out a portion extending in one direction and a portion orthogonal to that direction. Furthermore, as... Figure 36C As shown, the joining component 2 can also be set to a rhombus shape in the normal direction. Furthermore, in Figure 36B In this configuration, the corner of the joining member 2 is located on the imaginary line K2. However, even with such a configuration, by joining the joining member 2 only to a portion of the piezoelectric element 1 that is different from the corner, thermal stress is less likely to propagate to the corner of the piezoelectric element 1, thus achieving the same effect as the eleventh embodiment described above.

[0198] <Twelfth Implementation Method> The twelfth embodiment will be described. In this embodiment, a protrusion is formed on the printed circuit board 101, which is different from the first embodiment. As for other aspects, they are the same as those in the first embodiment, so the description is omitted here.

[0199] In the piezoelectric device S10 of this embodiment, such as Figure 37 As shown, a protrusion 101c is formed on the printed circuit board 101. Specifically, the protrusion 101c is shaped to match the shape of the bonding member 2 and is formed using a portion of the printed circuit board 101. For example, in this embodiment, the protrusion 101c is formed in a portion of the printed circuit board 101 that faces the piezoelectric element 1, and is different from the portion that faces the corner of the piezoelectric element 1.

[0200] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39° to 81°, thus achieving the same effect as the first embodiment described above.

[0201] (1) In this embodiment, a protrusion 101c is formed on the printed circuit board 101. Therefore, when the liquid bonding member 2 is coated, by coating the bonding member 2 on the protrusion 101c, the shape of the bonding member 2 that bonds to the piezoelectric element 1 can be easily adjusted. Therefore, a liquid bonding member can also be used as the bonding member 2, which can improve the selectivity of the bonding member 2. In particular, when the shape of the bonding member 2 is adjusted as in the eleventh embodiment described above, the shape of the bonding member 2 can be easily adjusted.

[0202] <Modifications of the Twelfth Embodiment> A variation of the twelfth embodiment described above will be described. In the twelfth embodiment described above, the protrusion 101c may also be constructed using a component different from the printed circuit board 101.

[0203] <Other Implementation Methods> This disclosure has been described in accordance with embodiments, but it should be understood that this disclosure is not limited to that embodiment or structure. This disclosure also includes various modifications and equivalent variations. Moreover, various combinations or methods, as well as other combinations or methods that include only one element, more elements, or fewer elements, also fall within the scope or spirit of this disclosure.

[0204] For example, in the above embodiments, the vibrating part 20 only needs to be configured to have at least one piezoelectric film 50 and one electrode film 60. In addition, the planar shape of the piezoelectric element 1 may not be rectangular, but a polygonal shape such as a pentagon or a hexagon.

[0205] Furthermore, in the above embodiments, the floating region 21b in the vibration unit 20 may not be divided into four vibration regions 22, but may be divided into three or fewer vibration regions 22, or may be divided into five or more vibration regions 22.

[0206] Moreover, in the above embodiments, such as Figure 38 As shown, the piezoelectric device S10 can also be configured such that a through hole 102a is formed in the cover portion 102. In this case, as... Figure 38 As shown, the pressure surface space S1 becomes the space on one side 22a of the vibration region 22 in the outer shell 100, and the rear space S2 becomes the space on the other side 22b of the vibration region 22 in the outer shell 100.

[0207] Furthermore, in the above embodiments, the slit 41 may not be formed to intersect at the center C, and the vibration region 22 may be configured to be supported on both sides by the supported region 21a. Accordingly, the resonant frequency of the piezoelectric element 1 can be increased, the frequency range that can maintain detection sensitivity can be broadened, and the detection accuracy can be further improved.

[0208] The above embodiments can also be appropriately combined. For example, the second embodiment can be combined with the third to twelfth embodiments to make the slit 41 have a cone portion 42 and a constant portion 43. The fourth and fifth embodiments can be combined with the sixth to twelfth embodiments to change the shape of the boundary portion B of the recess 10a and the vibration portion 20. The sixth embodiment can be combined with the seventh to twelfth embodiments to change the arrangement position of the first electrode portion 81 and the second electrode portion 82. The seventh embodiment can be combined with the eighth to twelfth embodiments to make the slit 41 cone-shaped with the slit width g narrowing towards the center portion C. The eighth embodiment can be combined with the ninth to twelfth embodiments to define the shape and arrangement of the vibration region 22 and the electrode film 60. The ninth embodiment can be combined with the tenth to twelfth embodiments to define the slit length L, etc. The tenth embodiment can be combined with the eleventh and twelfth embodiments to make the slit width g of the slit 41 vary along the thickness direction of the vibration region 22. The eleventh embodiment described above can also be combined with the twelfth embodiment described above to specify the placement position of the joining member 2. Furthermore, embodiments combining the above embodiments can be further combined with each other.

Claims

1. A piezoelectric element, characterized in that, have: The vibrating element outputs a pressure detection signal corresponding to the pressure; and Support body; The vibrating part has a support region supported by the support body and multiple vibration regions connected to the support region and floating from the support body. The vibrating part includes a piezoelectric membrane disposed on the support and an electrode membrane connected to the piezoelectric membrane. The vibration unit outputs the pressure detection signal based on the charge extracted through the electrode film generated by the deformation of the piezoelectric film. The plurality of vibration regions are separated from each other by slits. The slit is formed in a conical shape such that its width narrows from one side of the vibration region opposite to the support body side to the other side opposite to that side. The electrode film is positioned inside the slit in the normal direction with respect to the said side. The angle between the side surface constituting the cone and the surface parallel to the cone in the vibration region is set to 39° to 81°.

2. The piezoelectric element according to claim 1, characterized in that, The angle between the side surface constituting the cone and the surface parallel to the cone is set to 63° or less.

3. The piezoelectric element according to claim 1, characterized in that, The angle between the side surface constituting the cone and the surface parallel to the cone is set to 45° or more.

4. The piezoelectric element according to any one of claims 1 to 3, characterized in that, The slit is configured to connect the cone formed on one side of the vibration region and the constant portion formed on the other side with a constant width.

5. The piezoelectric element according to any one of claims 1 to 3, characterized in that, The slit is designed to be tapered, with its width narrowing from the support region side toward the end side of the vibration region opposite to the support region side.

6. The piezoelectric element according to any one of claims 1 to 3, characterized in that, In the normal direction relative to the side of the vibration region opposite to the support body side, the vibration region and the electrode film are arranged in a point-symmetrical manner with respect to the center of the vibration region.

7. The piezoelectric element according to claim 6, characterized in that, In the vibration region, the area on the support region side is designated as the first region, and the area different from the first region is designated as the second region. The piezoelectric film is made of a material with a hexagonal crystal structure. The electrode film is divided by six electrode film slits, and in the normal direction, the imaginary shape of the designated parts of each of the electrode film slits in the first region is set as hexagonal.

8. The piezoelectric element according to claim 6, characterized in that, The support body has a support base plate and an insulating film disposed on the support base plate and on which the vibration part is disposed. Recesses are formed on the support base plate and the insulating film to float the vibration region. The support substrate is made of silicon substrate. In the normal direction, the shape of the vibration region is set to a regular octagon.

9. The piezoelectric element according to any one of claims 1 to 3, characterized in that, In the normal direction relative to the side opposite to the support body side in the vibration region, the shape of the vibrating part is set as a polygon. In the normal direction, at least one of the electrode film and the vibration region is configured as a polygonal shape with a corner located at a different portion from the imaginary line connecting the opposite corners in the shape of the vibration part.

10. The piezoelectric element according to claim 1, characterized in that, The piezoelectric film is made of a material with a higher film stress than aluminum nitride.

11. The piezoelectric element according to claim 1, characterized in that, The piezoelectric film is made of scandium aluminum nitride.

12. A piezoelectric device comprising a piezoelectric element having a vibrating portion that outputs a pressure detection signal corresponding to pressure, characterized in that, have: The piezoelectric element according to any one of claims 1 to 3; as well as The housing has a mounting component that houses the piezoelectric element and a cover fixed to the mounting component in a manner that accommodates the piezoelectric element, and has a through hole that communicates with the outside to introduce the pressure.

13. The piezoelectric device according to claim 12, characterized in that, If we define the space within the outer casing that differs from the pressure-bearing surface space between the through-hole and the vibrating part as the rear space, define the acoustic compliance of the rear space as Cb, define the thickness of the vibration region as h, define the average width of the slit along the thickness direction as ga, define the air resistance as μ, and define the slit length along the side of the vibration region as L, then the slit length satisfies the following formula: [Equation 1] 。 14. The piezoelectric device according to claim 13, characterized in that, The support is mounted on the mounted component via a connecting member. The piezoelectric element is shaped as a polygon with corners, in the normal direction relative to the side opposite to the support in the vibration region. The joining component is positioned in the normal direction at a location different from the corner.

15. The piezoelectric device according to claim 14, characterized in that, In the normal direction, the shape of the joining member is set as a polygonal shape with corners located at a different part from the imaginary line connecting the opposite corners in the shape of the piezoelectric element.

16. The piezoelectric device according to claim 14, characterized in that, The mounted component has a protrusion formed in the portion where the engaging component is configured. The engaging component is disposed on the protrusion.

17. A method for manufacturing a piezoelectric element, characterized in that, The piezoelectric element comprises: The vibrating element outputs a pressure detection signal corresponding to the pressure; and Support body; The vibrating part has a support region supported by the support body and multiple vibration regions connected to the support region and floating from the support body. The vibrating part includes a piezoelectric membrane disposed on the support and an electrode membrane connected to the piezoelectric membrane. The vibration unit outputs the pressure detection signal based on the charge extracted through the electrode film generated by the deformation of the piezoelectric film. The plurality of vibration regions are separated from each other by slits. The slit is formed in a conical shape such that its width narrows from one side of the vibration region opposite to the support body side to the other side opposite to that side. The electrode film is positioned inside the slit in the normal direction with respect to the said side. The angle between the side surface constituting the cone and the surface parallel to the cone is set to 39° to 81°. The manufacturing method of the piezoelectric element includes the following steps: The step of forming the piezoelectric film and the electrode film on the support body; The step of disposing an etching mask material on the piezoelectric film and the electrode film, and forming an opening on the etching mask material that exposes the portion of the piezoelectric film to which the slit is to be formed; The steps of etching using the etching mask material as a mask to form a slit penetrating the piezoelectric film and reaching the support, forming a vibration region component having the cone portion; and The step of forming the vibrating part having the plurality of vibrating regions is to partially float the vibrating region by forming a recess from the side opposite to the piezoelectric film side of the support body; In the step of forming the slit, the slit is formed at an angle of 39° to 81°.

18. The method for manufacturing a piezoelectric element according to claim 17, characterized in that, In the step of forming the slit, the slit is formed at an angle of 63° or less.

19. The method for manufacturing a piezoelectric element according to claim 17 or 18, characterized in that, In the step of forming the slit, the slit is formed at an angle of 45° or more.

20. The method for manufacturing a piezoelectric element according to claim 17, characterized in that, The piezoelectric film is made of a material with a higher film stress than aluminum nitride.

21. The method for manufacturing a piezoelectric element according to claim 17, characterized in that, The piezoelectric film is made of scandium aluminum nitride.

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