Piezoelectric element, piezoelectric device, microphone

Abstract

To ensure a slit to be properly formed.SOLUTION: With a plurality of vibration regions 22, an interval of each vibration region is separated by a slit 41. The slit 41 is formed in such a state that a tapered unit 42 is constituted that becomes narrower from one surface 22a side opposite to a support 10 side in the vibration region 22 toward the other surface 22b side opposite to the one surface 22a. An electrode film 60 is arranged inside the slit 41 in a normal direction relative to the surface 22a. An angle θ1 defined by a side surface 22c constituting the tapered unit 42 in the vibration region 22 and the surfaces 22a, Sv in parallel to the surface 22a is set to be 39 to 81°.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a piezoelectric element and a piezoelectric device in which a vibration region is cantilever-supported. , Microphone It relates thereto.

Background Art

[0002] Conventionally, a piezoelectric element in which a vibration region is cantilever-supported by a support has been proposed (see, for example, Patent Document 1). Specifically, the piezoelectric element includes a support and a vibration portion disposed on the support. The vibration portion has a configuration including a piezoelectric film and an electrode film connected to the piezoelectric film. The piezoelectric film is made of aluminum nitride (hereinafter also simply referred to as AlN).

[0003] A recess is formed in the support for floating the inner edge side of the vibration portion. As a result, a floating region that floats on the recess is formed in the vibration portion. Further, in this piezoelectric element, a slit is formed in the floating region, and a vibration region in which the floating region is divided is formed. That is, a vibration region cantilever-supported by the support is formed.

[0004] Such a piezoelectric element is manufactured as follows. That is, a piezoelectric film and an electrode film are formed on a support. Next, a slit is formed in the piezoelectric film to form a vibration region constituent portion. Then, a recess is formed in the support, and the vibration region constituent portion is floated to form a vibration region, whereby the above piezoelectric element is manufactured.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the piezoelectric element as described above, it has been considered to use scandium aluminum nitride (hereinafter also simply referred to as ScAlN) having high piezoelectric characteristics as the piezoelectric film. However, ScAlN is a difficult-to-etch material. Therefore, when attempting to manufacture a piezoelectric element by the same manufacturing method as when using AlN as the piezoelectric film, when forming a slit, the formation of the slit cannot be appropriately performed, and the shape of the vibration region may vary.

[0007] In view of the above points, the present invention provides a piezoelectric element and a piezoelectric device in which a slit is appropriately formed. , Microphone The object is to provide.

Means for Solving the Problems

[0008] In claim 1 for achieving the above object , Branch A holding body (10), disposed on the support body, Composed of a material with a larger film stress than aluminum nitride A piezoelectric film (50), and an electrode film (60) connected to the piezoelectric film for extracting charges generated by the deformation of the piezoelectric film, having a support region (21a) supported by the support body, and being connected to the support region and floating from the support body A plurality of It has a vibration region (22), and outputs a pressure detection signal based on the charge Of vibration Moving part (20) and, and Comprising, The plurality of vibration regions are separated by a slit (41) between the vibration regions of each other, The slit has a tapered portion (42) whose width becomes narrower from one surface (22a) side opposite to the support body side in the vibration region toward the other surface (22b) side opposite to the one surface It is formed in a state where it is configured, and the electrode film is disposed inside the slit rather than the outside in the normal direction with respect to one surface, and the angle (θ1) formed by the side surface (22c) constituting the tapered portion in the vibration region and the surface (22b, Sv) parallel to one surface is 39° or more and 80° or less.

[0009] According to this, The angle formed by the vibration region is 39° or more and 80° or less. For this reason, it is possible to suppress a decrease in workability when the slit is formed, and the slit is appropriately formed. For this reason, it is possible to suppress a decrease in detection sensitivity.

[0010] Further, claim 12 is a piezoelectric device, comprising the piezoelectric element according to any one of claims 1 to 11, a mounted member (101) on which the piezoelectric element is mounted, and a casing (100) that houses the piezoelectric element. A through hole (101b) that communicates with the outside and into which pressure is introduced is formed at a position facing the other surface of the piezoelectric element in the casing. Claim 19is a microphone, comprising the piezoelectric element according to any one of claims 1 to 11, a mounted member (101) on which the piezoelectric element is mounted, and a casing (100) that houses the piezoelectric element. A through hole (101b) that communicates with the outside and into which pressure is introduced is formed in the casing at a position facing the other surface of the piezoelectric element.

[0011] According to this, Since it is provided with the piezoelectric element according to any one of claims 1 to 11, the same effects as those of the above piezoelectric element can be obtained.

[0014] Note that the reference signs in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0015] [[FIG. 1]] It is a cross-sectional view of the piezoelectric element in the first embodiment. [[FIG. 2]] It is a plan view of the piezoelectric element shown in FIG. 1. [[FIG. 3]] It is a schematic diagram of the vibration region shown in FIG. 1. [[FIG. 4A]] It is a cross-sectional view showing the manufacturing process of the piezoelectric element shown in FIG. 1. [[FIG. 4B]] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4A. [[FIG. 4C]] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4B. [[FIG. 4D]] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4C. [[FIG. 4E]] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4D. [[FIG. 5]] It is a schematic diagram of the portion where the slit is formed in the manufacturing process of FIG. 4D. [[FIG. 6]] It is a diagram showing the relationship between frequency, sensitivity, and effective width. [[FIG. 7]] It is a diagram showing the relationship between the film thickness of the etching mask material and the angle formed with respect to the film thickness of the piezoelectric film. [[FIG. 8]] It is a cross-sectional view of the piezoelectric device in the first embodiment. [[FIG. 9A]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 9B]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 9C]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 9D]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 9E]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 9F]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 9G]] It is a plan view of a vibration region in a modification of the first embodiment. [[FIG. 10]] It is a schematic diagram of a vibration region in the second embodiment. [[FIG. 11]] It is a cross-sectional view of a piezoelectric element in the third embodiment. [[FIG. 12]] It is a cross-sectional view of a piezoelectric element in the fourth embodiment. [[FIG. 13]] It is a cross-sectional view of a piezoelectric element in the fifth embodiment. [[FIG. 14]] It is a plan view of a piezoelectric element in the sixth embodiment. [[FIG. 15A]] It is a cross-sectional view taken along line XIV-XVA in FIG. 14. [[FIG. 15B]] It is a cross-sectional view taken along line XIV-XVB in FIG. 14. [[FIG. 16]] It is a plan view of an electrode film formed in the first region in the sixth embodiment. [[FIG. 17]] It is a circuit schematic diagram of a piezoelectric element in the sixth embodiment. [[FIG. 18]] It is a plan view of an electrode film formed in the first region in a modification of the sixth embodiment. [[FIG. 19]] It is a circuit schematic diagram of a piezoelectric element in a modification of the sixth embodiment. [[FIG. 20]] It is a plan view of a piezoelectric element in the seventh embodiment. [[FIG. 21]]It is a plan view of a piezoelectric element in the eighth embodiment. [[FIG. 22]] It is a plan view of an electrode film formed in the first region in the eighth embodiment. [[FIG. 23]] It is a circuit schematic diagram of a piezoelectric element in the eighth embodiment. [[FIG. 24]] It is a cross-sectional view of a piezoelectric element in the eighth embodiment. [[FIG. 25]] It is a plan view of a piezoelectric element in a modified example of the eighth embodiment. [[FIG. 26]] It is a plan view of an electrode film formed in the first region in the eighth embodiment. [[FIG. 27]] It is a circuit schematic diagram of a piezoelectric element in a modified example of the eighth embodiment. [[FIG. 28]] It is a cross-sectional schematic diagram of a piezoelectric device in the ninth embodiment. [[FIG. 29]] It is a diagram showing the relationship between the average slit width, slit length, and acoustic resistance when the thickness of the vibration region is constant. [[FIG. 30]] It is a diagram showing the relationship between the thickness of the vibration region, slit length, and acoustic resistance when the average slit width is constant. [[FIG. 31]] It is a diagram showing the relationship between the slit length and the acoustic resistance ratio. [[FIG. 32]] It is a cross-sectional view of a slit of a piezoelectric element in the tenth embodiment. [[FIG. 33]] It is a diagram showing the relationship between the slit width on one side and the acoustic resistance. [[FIG. 34]] It is a plan view showing the positional relationship between a piezoelectric element and a joining member in the eleventh embodiment. [[FIG. 35A]] It is a plan view showing the positional relationship between a piezoelectric element and a joining member in a modified example of the eleventh embodiment. [[FIG. 35B]] It is a plan view showing the positional relationship between a piezoelectric element and a joining member in a modified example of the eleventh embodiment. [[FIG. 36A]] It is a plan view showing the positional relationship between a piezoelectric element and a joining member in a modified example of the eleventh embodiment. [[FIG. 36B]]It is a plan view showing the positional relationship between the piezoelectric element and the joining member in a modification of the 11th embodiment. [[FIG. 36C]] It is a plan view showing the positional relationship between the piezoelectric element and the joining member in a modification of the 11th embodiment. [[FIG. 37]] It is a cross-sectional view of the piezoelectric device in the 12th embodiment. [[FIG. 38]] It is a cross-sectional view of the piezoelectric device in other embodiments.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals and will be described.

[0017] (First Embodiment) The piezoelectric element 1 of the first embodiment will be described with reference to FIGS. 1 and 2. Note that the piezoelectric element 1 of this embodiment is preferably used as a microphone, for example. Also, in FIG. 2, the first electrode portion 81, the second electrode portion 82, etc. described later are omitted. And in each figure corresponding to FIG. 2 described later, the first electrode portion 81, the second electrode portion 82, etc. are also omitted as appropriate.

[0018] The piezoelectric element 1 includes a support 10 and a vibrating portion 20, and has a rectangular planar shape. The support 10 has a support substrate 11 having a first surface 11a and a second surface 11b, and an insulating film 12 formed on the support substrate 11. Note that the support substrate 11 is composed of, for example, a silicon substrate or the like, and the insulating film 12 is composed of an oxide film or the like.

[0019] The vibrating part 20 constitutes a sensing part 30 that outputs a pressure detection signal corresponding to sound pressure or the like as pressure, and is disposed on the support 10. And, a recess 10a for floating the inner edge side of the vibrating part 20 is formed in the support 10. For this reason, the vibrating part 20 has a configuration including a support region 21a disposed on the support 10 and a floating region 21b that is connected to the support region 21a and floats on the recess 10a. Note that, in the recess 10a of the present embodiment, the shape of the opening end on the vibrating part 20 side (hereinafter, also simply referred to as the opening end of the recess 10a) is a planar rectangular shape. Therefore, the entire floating region 21b is substantially planar rectangular.

[0020] The floating region 21b of the present embodiment is divided by slits 41 so that four vibrating regions 22 are formed. In the present embodiment, two slits 41 are formed so as to pass through the center part C of the floating region 21b and extend toward opposite corner parts of the floating region 21b. In other words, the slits 41 extend from each corner part of the floating region 21b having a planar rectangular shape toward the center part C, and are formed so that the respective slits 41 intersect at the center part C. Thereby, the floating region 21b is separated into four vibrating regions 22 having a substantially planar triangular shape. Although not particularly limited, in the present embodiment, the interval between the respective vibrating regions 22 (that is, the average width of the slits 41) is about 1 μm. Note that the slits 41 are formed by anisotropic dry etching as will be described later in the present embodiment.

[0021] Here, the shape of the slit 41 of this embodiment will be specifically described. First, as shown in FIGS. 1 and 3, the surface on the side opposite to the support 10 in the vibration region 22 is defined as one surface 22a, and the surface on the support 10 side in the vibration region 22 is defined as the other surface 22b. In this case, the slit 41 is formed such that a tapered portion 42 is formed in which the slit width g becomes narrower from the one surface 22a side toward the other surface 22b side. In other words, when the surface connecting the one surface 22a and the other surface 22b in the vibration region 22 is defined as the side surface 22c, the slit 41 is formed such that the side surface 22c becomes the tapered portion 42. Further, the slit 41 of this embodiment has a shape in which the slit width g continuously becomes narrower from the one surface 22a side toward the other surface 22b side. That is, the slit 41 is formed such that the side surface 22c of the vibration region 22 is substantially planar.

[0022] Note that the one surface 22a and the other surface 22b of the vibration region 22 are parallel. Also, the slit width g of the slit 41 is, in other words, the distance between the respective side surfaces 22c in the opposing vibration regions 22. The side surface 22c of the vibration region 22 is the surface formed by the slit 41.

[0023] Further, the slit 41 is formed such that the angle θ1 formed by the other surface 22b and the side surface 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 surface 22b corresponds to a surface parallel to the one surface 22a. Also, the formed angle θ1 can be said to be the taper angle of the slit 41. The above is the shape of the slit 41 in this embodiment.

[0024] And since each vibration region 22 is configured by dividing the floating region 21b as described above, one end portion 22d is a fixed end supported by the support 10 (that is, the support region 21a), and the other end portion 22e is a free end, and it is a cantilever. That is, each vibration region 22 is in a state of being connected to the support region 21a and is in a state of being supported at one end.

[0025] The vibrating part 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 laminated on the lower piezoelectric film 51. Further, 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 part 20 has a bimorph 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.

[0026] Furthermore, the vibrating part 20 of the present embodiment has a base film 70 on which the lower piezoelectric film 51 and the lower electrode film 61 are disposed. That is, on the support 10, the piezoelectric film 50 and the electrode film 60 are disposed 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 and the like.

[0027] 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 or the like. Also, the piezoelectric film 50 has a thickness of about one thousand nm, and the base film 70 has a thickness of about several tens of nm. That is, the base film 70 is extremely thin compared to the piezoelectric film 50.

[0028] In addition, in each vibration region 22 of the present embodiment, the fixed end side is the first region R1, and the free end side is the second region R2. 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 are separated from and insulated from the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2. Further, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 are appropriately extended to the support region 21a.

[0029] Note that 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 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 disposed inside the slit 41 in the normal direction with respect to one surface 22a of the vibration region 22. For this reason, 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 surface 22a of the vibration region 22 is simply referred to as the normal direction. In addition, in the normal direction with respect to one surface 22a of the vibration region 22 can also be said to be when viewed from the normal direction with respect to one surface 22a of the vibration region 22.

[0030] In the support region 21a of the vibrating portion 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. Note that FIG. 1 is a cross-sectional view taken along line I-I in FIG. 2, showing different cross-sections of the vibration region 22 on the left side of the paper surface and the vibration region 22 on the right side of the paper surface. In FIG. 2, the first electrode portion 81 and the second electrode portion 82 are omitted.

[0031] The first electrode portion 81 is formed in a hole portion 81a that penetrates the upper electrode film 63, the upper piezoelectric film 52, and the lower piezoelectric film 51 to expose the lower electrode film 61, and has a through electrode 81b that is electrically connected to the lower electrode film 61 and the upper electrode film 63. Further, the first electrode portion 81 has a pad portion 81c that is formed on the through electrode 81b and is electrically connected to the through electrode 81b. The second electrode portion 82 is formed in a hole portion 82a that penetrates the upper piezoelectric film 52 to expose the intermediate electrode film 62, and has a through electrode 82b that is electrically connected to the intermediate electrode film 62. Further, the second electrode portion 82 has a pad portion 82c that is formed on the through electrode 82b and is electrically connected to the through electrode 82b. The first electrode portion 81 and the second electrode portion 82 are formed using molybdenum, copper, platinum, titanium, aluminum, etc., in the same manner as the electrode film 60.

[0032] Note that 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 are in a floating state. For this reason, 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, but in the present embodiment, they are provided to protect the portions of the lower piezoelectric film 51 and the upper piezoelectric film 52 that are located in the second region R2.

[0033] Further, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 are divided by the slit 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 so as to straddle each vibration region 22. Then, 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 a wiring film (not shown) or the like.

[0034] Note that the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 of the present embodiment are formed so that their outer shapes are substantially equal to the outer shape of the vibration region 22, and are formed in a planar rectangular shape in the present embodiment. However, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are divided by the respective vibration regions 22 as described above. Therefore, the outer shapes of the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 here refer to the shapes constituted by the outer shape lines and the extension lines of the outer shape lines in the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63.

[0035] And the sensing unit 30 of the present embodiment is configured to output the change in charge in the four vibration regions 22 as one pressure detection signal. That is, the four vibration regions 22 are electrically connected in series. More specifically, each vibration region 22 has a bimorph structure, and each lower electrode film 61, each intermediate electrode film 62, and each upper electrode film 63 formed in each vibration region 22 are connected in parallel, while the vibration regions 22 are connected in series.

[0036] The above is the configuration of the piezoelectric element 1 in the present embodiment. When a sound pressure is applied to each vibration region 22 (that is, the sensing unit 30), such a piezoelectric element 1 causes each vibration region 22 to vibrate. In this case, for example, when the other end 22e side (that is, the free end side) of the vibration region 22 is displaced upward, a tensile stress is generated in the lower piezoelectric film 51, and a compressive stress is generated in the upper piezoelectric film 52. Therefore, the sound pressure is detected by extracting the charge from the first electrode portion 81 and the second electrode portion 82.

[0037] At this time, the stress generated in the vibration region 22 (i.e., the piezoelectric film 50) is greater on the fixed end side than on the free end side because the stress is released on the free end side (i.e., the other end portion 22e side). That is, on the free end side, the generation of charges is reduced, and the signal-to-noise ratio (SN ratio) is likely to be small. Therefore, in the piezoelectric element 1 of the present embodiment, as described above, each vibration region 22 is divided into a first region R1 where the stress is likely to increase and a second region R2 where the stress is likely to decrease. 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 charges generated in the lower piezoelectric film 51 and the upper piezoelectric film 52 located in the first region R1 are extracted. Thereby, it is possible to suppress an increase in the influence of noise.

[0038] Next, a method for manufacturing the piezoelectric element 1 will be described with reference to FIGS. 4A to 4E, FIG. 5, and FIG. 6.

[0039] First, as shown in FIG. 4A, a structure in which a base film 70, a piezoelectric film 50, an electrode film 60, a first electrode portion 81, a second electrode portion 82, etc. are formed on a support 10 having a support substrate 11 and an insulating film 12 is prepared. That is, a structure in which the recess 10a and the slit 41 shown in FIG. 1 are not formed is prepared. Note that the piezoelectric film 50, the electrode film 60, etc. formed in the process of FIG. 4A are parts that constitute the vibrating portion 20. Therefore, in FIG. 4A, the same reference numerals are given to one surface 22a and the other surface 22b of the vibration region 22. Further, the arrangement position of the electrode film 60 is adjusted so as not to be exposed from the portion where the slit 41 is formed.

[0040] Here, the base film 70, the piezoelectric film 50, the electrode film 60, etc. are formed by appropriately performing general sputtering, etching, etc. In this case, when forming the base film 70 and the lower electrode film 61 as the electrode film 60 on the support 10, since the linear expansion coefficients of the base film 70 and the lower electrode film 61 are larger than the linear expansion coefficient of the support 10, they are formed in a state where tensile stress remains. Therefore, when the piezoelectric film 50 is formed as it is, the piezoelectric film 50 is likely to be formed in a state where tensile stress remains due to the tensile stress of the base film 70 and the lower electrode film 61. And when tensile stress remains in the piezoelectric film 50, characteristic variations of the piezoelectric element 1 are likely to occur. Therefore, when forming the piezoelectric film 50, for example, it is preferable to do as follows.

[0041] For example, when forming the upper piezoelectric film 52, it is preferable to increase the voltage applied during sputtering compared to when forming the lower piezoelectric film 51 so that compressive stress is generated in the upper piezoelectric film 52. Thereby, the tensile stress of the lower piezoelectric film 51 and the compressive stress of the upper piezoelectric film 52 are offset, and the stress remaining inside the piezoelectric film 50 as a whole can be reduced. In this case, the upper piezoelectric film 52 may be formed by multiple sputterings. And by generating tensile stress in the portion of the upper piezoelectric film 52 on the side of the lower piezoelectric film 51 and generating compressive stress in the uppermost layer side portion opposite to the lower piezoelectric film 51, the stress remaining inside the piezoelectric film 50 may be reduced.

[0042] Subsequently, as shown in FIG. 4B, an etching mask material 200 made of a photoresist or the like is disposed so as to cover the upper electrode film 63 and the like, and an opening 201 is formed in the etching mask material 200 where the portion where the slit 41 is formed is open. Hereinafter, the surface of the etching mask material 200 that covers the upper electrode film 63 and the upper piezoelectric film 52 is referred to as the other surface 200b, the surface of the etching mask material 200 opposite to the other surface 200b is referred to as the one surface 200a, and the side surface of the opening 201 is referred to as the side surface 200c.

[0043] Next, as shown in FIG. 4C, by performing a heat treatment, the shape of the opening 201 of the etching mask material 200 is adjusted. Specifically, the etching mask material 200 is disposed so as to cover the upper electrode film 63 and the upper piezoelectric film 52, and the way of thermal contraction is different between the portion on the other surface 200b side fixed to these and the portion on the one surface 200a side. More specifically, when the heat treatment is performed, in the etching mask material 200, the portion on the other surface 200b side becomes difficult to thermally contract, and the portion on the one surface 200a side becomes easy to thermally contract. Therefore, by performing the heat treatment, the angle θ2 formed by the other surface 200b and the side surface 200c of the etching mask material 200 (hereinafter, also simply referred to as the angle θ2 formed by the etching mask material 200) is adjusted to match the angle θ1 formed by the desired vibration region 22. In this case, since the piezoelectric film 50 and the etching mask material 200 are made of different materials, usually the etching rates are different when anisotropic dry etching described later is performed. Therefore, based on the etching rate and the like, the angle θ2 formed by the etching mask material 200 is adjusted so that the angle θ1 formed by the vibration region 22 becomes a desired value. Note that the angle θ2 formed by the etching mask material 200 here may match the angle θ1 formed by the vibration region 22 as adjusted above, or may not match the angle θ1 formed by the vibration region 22.

[0044] Next, as shown in FIG. 4D, anisotropic dry etching is performed using the etching mask material 200 as a mask to form a slit 41 that penetrates the piezoelectric film 50 and reaches the support 10. In the present embodiment, the slit 41 is formed so as to form four vibration region components 220 each having a side surface 22c that becomes a tapered portion 42.

[0045] 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 component 220 is set to 39 to 81°. Note that the vibration region component 220 is a portion that becomes the vibration region 22 by forming a concave portion 10a described later. Therefore, the angle θ1 formed by the vibration region component 220 and the angle θ1 formed by the vibration region 22 are the same. In the figure, the same reference numerals are given to one surface, the other surface, and the side surface of the vibration region 22 as those of one surface 22a, the other surface 22b, and the side surface 22c of the vibration region component 220. Also, the shapes of the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are adjusted so as not to reach the slit 41. Therefore, in this step, the piezoelectric film 50 and the base film 70 are anisotropically dry-etched.

[0046] Thereafter, as shown in FIG. 4E, using a mask (not shown), etching is performed from the other surface 11b of the support substrate 11 so as to penetrate the insulating film 12 and reach the base film 70 to form the concave portion 10a. In the present embodiment, after removing the support substrate 11 by anisotropic dry etching, the insulating film 12 is removed by isotropic wet etching to form the concave portion 10a. As a result, the vibration region component 220 floats from the support 10 to form the vibration region 22, and the piezoelectric element 1 shown in FIG. 1 is manufactured.

[0047] Note that, in this step, although not particularly shown, a protective resist or the like covering the upper piezoelectric film 52 and the upper electrode film 63 may be disposed to form the concave portion 10a. Thereby, it is possible to suppress the vibration region 22 from being destroyed when the concave portion 10a is formed. However, the protective resist is removed after the concave portion 10a is formed.

[0048] Next, the angle θ1 formed by the vibration region component 220 (that is, the vibration region 22) in the manufacturing process of the present embodiment will be described.

[0049] First, according to the study by the present inventors, when anisotropically dry-etching a piezoelectric film 50 such as ScAlN, the following phenomenon was confirmed when the formed angle θ1 is 81° or more. That is, when the formed angle θ1 is 81° or more, it was confirmed that the workability tends to decrease due to the influence of redeposition where the etched atoms redeposit on the side surface 22c of the slit 41. Furthermore, according to the study by the present inventors, when anisotropically dry-etching a piezoelectric film 50 such as ScAlN, the following phenomenon was confirmed when the formed angle θ1 is 63° or more. That is, when the formed angle θ1 is 63° or more, it was confirmed that the workability tends to decrease due to the influence of a fence formed by the redeposition of the etched atoms near the opening on the one surface 22a side in the slit 41. Therefore, when forming the slit 41, it is preferable that the formed angle θ1 is 63° or less. Thereby, it is possible to suppress the decrease in workability due to a fence or the like.

[0050] Also, ScAlN constituting the piezoelectric film 50 is a material difficult to etch. And according to the study by the present inventors, when forming the slit 41 penetrating the piezoelectric film 50, in order to leave the etching mask material 200 on the piezoelectric film 50, it was confirmed that it is preferable to make the film thickness of the etching mask material 200 3 to 5 times the film thickness of the piezoelectric film 50. In other words, when forming the slit 41 penetrating the piezoelectric film 50, in order to prevent the piezoelectric film 50 covered with the etching mask material 200 from being removed by anisotropic dry etching, it was confirmed that it is preferable to make the film thickness of the etching mask material 200 3 to 5 times the film thickness of the piezoelectric film 50. That is, as shown in FIG. 5, when the film thickness of the piezoelectric film 50 is A1 and the film thickness of the etching mask material 200 is A2, the film thickness A2 of the etching mask material 200 is preferably 3A1 to 5A1. Note that the underlayer film 70 of the present embodiment is formed extremely thin with respect to the piezoelectric film 50 as described above. Therefore, the influence of the underlayer film 70 is ignored.

[0051] In addition, when forming the slit 41, it is also affected by the exposure constraints of the processing apparatus. According to the study by the present inventors, in a current general processing apparatus, as shown in FIG. 5, when the width on the one surface 22a side in the slit 41 is defined as the slit width g, the resolution of the slit width g with respect to the film thickness A2 of the etching mask material 200 was confirmed to have a limit of 1 / 2 to 1 / 3 of the film thickness A2 of the etching mask material 200. Therefore, since the film thickness A2 of the etching mask material 200 is represented by 3A1 to 5A1, the range of the slit width g is limited to 3A1 / 3 to 5A1 / 2.

[0052] And in the piezoelectric element 1 as described above, sound pressure leaks out from the slit 41. In this case, as shown in FIG. 6, the longer the effective width of the slit 41, the lower the sensitivity at low frequencies. For this reason, it is preferable that the slit 41 is formed so that the effective width becomes narrow. The effective width of the slit 41 is the average width of the slit 41. For example, when the slit 41 is tapered so that the width continuously narrows from the one surface 22a toward the other surface 22b as in the present embodiment, it is the average of the width on the one surface 22a side and the width on the other surface 22b side.

[0053] In addition, since the slit 41 of the present embodiment is formed by anisotropic dry etching, the side surface 22c becomes substantially flat. For this reason, assuming that the width on the other surface 22b side in the slit 41 is substantially 0 so as to suppress a decrease in sensitivity, the film pressure of the piezoelectric film 50 is A1, and the slit width on the one surface 22a side is g, then tanθ1 = A1 / (g / 2). Note that g / 2 can also be said to be the slit effective width. Therefore, since the slit width g is 3A1 / 3 to 5A1 / 2 as described above, tanθ1 = 2 to 0.8, and θ1 = 39 to 63° is preferable.

[0054] Then, upon further examination by the present inventors, it was confirmed that the film thickness A2 of the etching mask material 200 may 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 may be A1 to 5A1. Therefore, the slit width g is limited to A1 / 3 to 5A1 / 2. For this reason, according to further examination by the present inventors, tanθ1 = 6 to 0.8, and θ1 = 39 to 81° is preferable. Therefore, when forming the slit 41, it is preferable that the angle θ1 formed by the vibration region component 220 is 39 to 81°. Thereby, it is possible to suppress a decrease in the workability of the slit 41 due to the film thickness A2 of the etching mask material 200.

[0055] In addition, summarizing 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 formed angle, it becomes as shown in FIG. 7. And, as described above, the resolution of the slit width g with respect to the film thickness A2 of the etching mask material 200 is limited to 1 / 2 to 1 / 3 of the film thickness A2 of the etching mask material 200. For this reason, the lower limit of the formed angle θ1, 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.

[0056] Here, as the piezoelectric element 1 of the comparative example, there is an example in which a piezoelectric film 50 made of a material that is easy to etch, such as AlN, is used, and the side surface 22c of the vibration region 22 is substantially perpendicular to the other surface 22b. And, let the effective width of the slit 41 in the piezoelectric element 1 of the comparative example be g. In this case, when the effective width in the piezoelectric element 1 of the present embodiment is g or more, the width of the slit 41 widens, so there is a possibility that the sensitivity is lower than that of the piezoelectric element 1 of the comparative example.

[0057] Therefore, it is preferable that the slit 41 is formed such that the effective width is equal to or less than the execution width of the slit 41 in the piezoelectric element 1 of the comparative example. That is, it is preferably configured such that tanθ1 is 1 or more. For this reason, θ1 is preferably 45° or more, and preferably 45 to 81°. Thereby, it is possible to suppress a decrease in sensitivity. In this case, by setting θ1 to 63° or less, it is also possible to suppress a decrease in the workability of the slit 41 due to a fence or the like.

[0058] Next, a piezoelectric device S10 using the piezoelectric element 1 will be described.

[0059] As shown in FIG. 8, the piezoelectric device of the present embodiment is configured such that the piezoelectric element 1 is housed in a casing 100. The casing 100 includes a printed circuit board 101 on which the piezoelectric element 1 and a circuit board 110 that performs predetermined signal processing and the like are mounted, and a lid portion 102 that is fixed to the printed circuit board 101 so as to house the piezoelectric element 1 and the circuit board 110. In the present embodiment, the printed circuit board 101 corresponds to the member to be mounted.

[0060] Although not particularly shown, the printed circuit board 101 is configured such that wiring portions, through-hole electrodes, and the like are appropriately formed, and electronic components such as capacitors (not shown) are also mounted as necessary. The piezoelectric element 1 is mounted on one surface 101a of the printed circuit board 101 via a bonding member 2 such as an adhesive on the other surface 11b of the support substrate 11. The circuit board 110 is mounted on one surface 101a of the printed circuit board 101 via a bonding member 111 made of a conductive member. The pad portion 82c of the piezoelectric element 1 and the circuit board 110 are electrically connected via a bonding wire 120. The pad portion 81c of the piezoelectric element 1 is electrically connected to the circuit board 110 via a bonding wire 120 in a cross-section different from that of FIG. 8. The lid portion 102 is made of metal, plastic, resin, or the like, and is fixed to the printed circuit board 101 via a bonding member such as an adhesive (not shown) so as to house the piezoelectric element 1 and the circuit board 110.

[0061] In this embodiment, a through-hole 101b is formed in a portion of the printed circuit board 101 that faces the sensing unit 30. Specifically, the through-hole 101b has a substantially cylindrical shape and is formed such that its central axis coincides with the central portion C of the vibration region 22 in the normal direction.

[0062] The above is the configuration of the piezoelectric device S10 in this embodiment. Hereinafter, in the casing 100, the space between the portion where the through-hole 101b is formed and the vibration region 22 is defined as the pressure-receiving surface space S1. Also, the space that includes the space located on the side opposite to the pressure-receiving surface space S1 with the vibration region 22 interposed therebetween and that is continuous without passing through the slit 41 is defined as the back space S2. Note that the back space S2 can also be said to be a space different from the pressure-receiving surface space S1 in the space within the casing 100, or can be said to be the space excluding the pressure-receiving surface space S1. More specifically, the pressure-receiving surface space S1 can also be said to be a space that affects the pressing of the surface of the vibration region 22 on the side of the through-hole 101b formed in the casing 100 (that is, the other surface 22b in this embodiment). The back space S2 can also be said to be a space that affects the pressing of the surface of the vibration region 22 on the side opposite to the side where the through-hole 101b is formed in the casing 100 (that is, the one surface 22a in this embodiment).

[0063] In such a piezoelectric device S10, sound pressure as pressure is introduced into the pressure-receiving surface space S1, whereby sound pressure is applied to the vibration region 22 (that is, the sensing unit 30), and the sound pressure is detected as described above.

[0064] According to the embodiment described above, the angle θ1 formed by the vibration region 22 is set to 39 to 81°. Therefore, it is possible to suppress a decrease in the workability of the slit 41 due to the film thickness A2 of the etching mask material 200, and the slit 41 can be preferably formed. Also, since the angle θ1 is 81° or less, the influence of re-deposition can be reduced, and a decrease in workability can be suppressed.

[0065] (1) In this embodiment, by setting the angle θ formed by the vibration region 22 to 63° or less, it is possible to suppress a decrease in workability due to the influence of the fence.

[0066] (2) In this embodiment, by setting the angle θ1 formed by the vibration region 22 to 45° or more, it is possible to suppress a decrease in sensitivity.

[0067] (Modification of the First Embodiment) A modification of the first embodiment will be described. In the first embodiment, when forming the slit 41, dry etching may be performed after wet etching. According to this, since the etching mask material 200 is not removed during wet etching, the thickness A2 of the etching mask material 200 defined based on the thickness A1 of the piezoelectric film 50 can be made thinner, and the slit width g defined by the thickness A2 of the etching mask material 200 can be made narrower. Therefore, the effective width g / 2 can be made narrower, and the sensitivity can be improved.

[0068] Also, in the first embodiment, the planar shape in the vibration region 22 can be appropriately changed. For example, as shown in FIGS. 9A to 9G, the planar shape of the vibration region 22 may be hexagonal, octagonal, decagonal, dodecagonal, tetradecagonal, hexadecagonal, or circular. Also, although not particularly shown, the vibration region 22 may have other polygonal shapes. In FIGS. 9A to 9G, the slit 41 formed in the vibration region 22 is omitted, but the slit 41 is formed in each of the vibration regions 22. For example, when the planar shape of the vibration region 22 is hexagonal as shown in FIG. 9A, the slit 41 is formed so as to intersect at the center C from each corner of the outer shape of the vibration region 22. Also, when the planar shape of the vibration region 22 is circular as shown in FIG. 9G, a plurality of desired slits 41 are formed evenly in the circumferential direction so as to intersect at the center.

[0069] (Second Embodiment) The second embodiment will be described. This embodiment is the same as the first embodiment except that the shape of the slit 41 is changed. Since the other aspects are the same as those of the first embodiment, the description thereof will be omitted here.

[0070] In the piezoelectric element 1 of this embodiment, as shown in FIG. 10, the slit 41 is formed such that a tapered portion 42 tapered on the one surface 22a side and a constant portion 43 having a constant width are formed on the other surface 22b side. That is, the slit 41 is formed on the other surface 22b side such that a constant portion 43 in which the side surface 22c is perpendicular to the other surface 22b is formed. The slit 41 has a configuration in which the tapered portion 42 and the constant portion 43 are connected. In this embodiment, the angle θ1 formed by the tapered portion 42 and the virtual plane Sv parallel to the one surface 22a is set to 39 to 81°.

[0071] Such a slit 41 can be formed, for example, by removing the etching mask material 200 after forming the tapered portion 42, arranging another etching mask material, and performing anisotropic dry etching so that the constant portion 43 is formed. Note that the opening formed in the other etching mask material when forming the constant portion 43 is formed such that the angle formed by the side surface of the opening and the other surface of the etching mask material is approximately 90°.

[0072] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is set to 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0073] (1) In this embodiment, the slit 41 is formed such that a tapered portion 42 having a tapered shape and a constant portion 43 having a constant width are formed. Therefore, for example, when compared with the piezoelectric element 1 in which the width on the one surface 22a side of the slit 41 and the width on the other surface 22b side of the slit 41 are the same, the effective width of the piezoelectric element 1 of this embodiment can be made narrower. Therefore, it is difficult for sound pressure to escape, and the sensitivity can be improved.

[0074] (Third Embodiment) A description will be given of the third embodiment. This embodiment is obtained by changing the shape of the boundary portion between the recess 10a and the vibrating portion 20 with respect to the first embodiment. Since other aspects are the same as those of the first embodiment, the description thereof will be omitted here.

[0075] As shown in FIG. 11, in the piezoelectric element 1 of this embodiment, the boundary portion B between the open end of the recess 10a and the vibrating portion 20 has a curved shape. In this embodiment, the recess 10a is formed such that its open end reaches the underlying film 70, and the boundary portion B between the recess 10a and the underlying film 70 has a curved shape. Such a curved shape is formed, for example, by performing isotropic wet etching when removing the insulating film 12 so as to also remove a part of the underlying film 70.

[0076] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0077] (1) In this embodiment, the boundary portion B between the recess 10a and the vibrating portion 20 has a curved shape. Therefore, when sound pressure is applied to the vibration region 22, it is possible to suppress stress from concentrating on the boundary portion B between the recess 10a and the vibrating portion 20, and it is possible to suppress the vibration region 22 from being destroyed.

[0078] (Fourth Embodiment) A description will be given of the fourth embodiment. This embodiment is obtained by arranging a high-strength material in the underlying film 70 with respect to the third embodiment. Since other aspects are the same as those of the third embodiment, the description thereof will be omitted here.

[0079] As shown in FIG. 12, in the piezoelectric element 1 of this embodiment, a protective member 71 made of a material having a higher strength than the underlying film 70 is arranged at the boundary portion B between the recess 10a and the underlying film 70 of the underlying film 70. The protective member 71 is made of, for example, a nitride film or the like.

[0080] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0081] (1) In the present embodiment, the protection member 71 is disposed at the boundary portion B with the concave portion 10a in the base film 70. That is, the protection member 71 is disposed at a portion where stress is likely to concentrate when sound pressure is applied to the vibration region 22. Therefore, it is possible to suppress the vibration region 22 from being destroyed when sound pressure is applied to the vibration region 22.

[0082] (Fifth Embodiment) The fifth embodiment will be described. This embodiment is a combination of the third embodiment and the fourth embodiment. Since other aspects are the same as those of the third embodiment, the description thereof will be omitted here.

[0083] As shown in FIG. 13, in the piezoelectric element 1 of the present embodiment, the protection member 71 is disposed at the boundary portion B with the concave portion 10a in the base film 70. And the boundary portion B of the protection member 71 with the concave portion 10a is formed in a curved shape.

[0084] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0085] (1) In the present embodiment, the protection member 71 is disposed at the boundary portion B with the concave portion 10a in the base film 70. And the boundary portion B of the protection member 71 with the concave portion 10a is formed in a curved shape. Therefore, it is possible to further suppress the vibration region 22 from being destroyed.

[0086] (Sixth Embodiment) The sixth embodiment will be described. In this embodiment, the arrangement of the first electrode portion 81 and the second electrode portion 82 is changed with respect to the first embodiment. Since other aspects are the same as those of the first embodiment, the description thereof will be omitted here.

[0087] As shown in Fig. 14, the piezoelectric element 1 of this embodiment has the same planar configuration as that of the first embodiment. In this embodiment, as shown in Fig. 14, for the four vibration regions 22, one vibration region 22 is defined as the first vibration region 221, and the second to fourth vibration regions 222 to 224 are defined in the circumferential direction starting from the first vibration region 221.

[0088] As shown in Fig. 15A, 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. As shown in Fig. 15B, the second electrode portion 82 is connected to the intermediate electrode film 62 formed in the fourth vibration region 224.

[0089] As shown in Fig. 16, the electrode film 60 of this embodiment is formed such that the outer shape of the portion formed in the first region R1 is substantially equal to the outer shape of the vibration region 22, and is rectangular in plan view in this embodiment. However, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are divided by the first to fourth vibration regions 221 to 224 as described above. Therefore, the outer shape of the portions of the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 here refers to the outer shape line of the portions located in the first region R1 in the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 and the shape formed by the extension lines of the outer shape line. Also, although shown as the electrode film 60 in Fig. 17, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 that form the electrode film 60 have the same shape as the electrode film 60 in Fig. 17 in the first region R1, respectively.

[0090] In this embodiment, as shown in Fig. 17, the circuit configuration is such that the vibration regions 221 to 224 are connected in series in order.

[0091] According to the present embodiment described above, since the angle θ1 formed by the vibration regions 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0092] (1) In this embodiment, the first to fourth vibration regions 221 to 224 are connected in series in order. Therefore, the routing of the wiring portion connecting the electrode films 60 of the respective vibration regions 221 to 224 can be facilitated.

[0093] (Modification of the Sixth Embodiment) A modification of the sixth embodiment will be described. In the piezoelectric element 1 of this embodiment, as shown in FIG. 18, the electrode film 60 may be divided into a plurality of charge regions 60a in the first region R1. For example, the electrode film 60 may be divided into three charge regions 60a in the first region R1 of each of the vibration regions 221 to 224. Note that the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 that form the electrode film 60 are each divided into charge regions 60a as shown in FIG. 18 in the first region R1. In this case, as shown in FIG. 19, the piezoelectric element 1 is in a state where the capacitances formed by the divided charge regions 60a are connected in series. According to this, the capacitance within each of the vibration regions 221 to 224 can be reduced, and the output can be improved. That is, the detection sensitivity can be improved.

[0094] (Seventh Embodiment) The seventh embodiment will be described. This embodiment is the same as the first embodiment except that the shape of the slit 41 is changed. Therefore, the description thereof will be omitted here.

[0095] In the piezoelectric element 1 of this embodiment, as shown in FIG. 20, the slit 41 has a tapered shape in which the slit width g is narrowed from the support region 21a side toward the center C of the floating region 21b in the normal direction. In other words, the slit 41 has a tapered shape in which the slit width g is narrowed from the support region 21a side toward the other end 21e side of the vibration region 22 in the normal direction.

[0096] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained. °

[0097] (1) In this embodiment, the slit 41 is tapered such that the slit width g decreases toward the center C of the floating region 21b. Therefore, when a sound pressure is applied to the vibration region 22 and the vibration region 22 bends, the slit width g of each slit 41 in the bent state is likely to be uniform. In other words, when the vibration region 22 bends, each slit 41 is likely to have a uniform slit width g between the portion on the support region 21a side and the portion on the center c side in the normal direction. Therefore, it is difficult for a difference to occur in the ease of leakage of local sound pressure within each slit 41, and noise can be reduced. For this reason, the detection accuracy can be further improved.

[0098] (Eighth Embodiment) In this embodiment, the shapes of the vibration region 22 and the intermediate electrode film 62 are adjusted with respect to the first embodiment. Since other aspects are the same as those of the first embodiment, the description thereof is omitted here.

[0099] The piezoelectric element 1 of this embodiment will be described with reference to FIGS. 21 and 22. Note that in FIG. 21, the slit 41 is shown omitted. However, the slit 41 actually extends from each corner portion in the planar shape of the vibration region 22 toward the center C in the same manner as in the first embodiment described above.

[0100] As shown in FIG. 21, the outer shape of the vibration region 22 is a regular octagon in the normal direction. That is, the shape of the opening of the recess 10a of the support 10 is a regular octagon. Hereinafter, the reason why the vibration region 22 is a regular octagon will be described. As described above, in this embodiment, the support substrate 11 is made of silicon. Therefore, by making the shape of the opening of the recess 10a (that is, the outer shape of the vibration region 22) a regular octagon, it is possible to suppress the concentration of strain at local portions of the open end of the recess 10a in the support substrate 11 (that is, the outer end portion of the vibration region 22). For this reason, it is possible to suppress the concentration of strain at local portions of the boundary portion between the support region 21a and the vibration region 22.

[0101] Further, as shown in FIG. 22, in the electrode film 60 of the present embodiment, in the normal direction, the outer shape of the portion formed in the first region R1 is a regular octagon. That is, the electrode film 60 is formed such that the outer edge portion substantially coincides with the opening end of the concave portion 10a in the first region. And the portion of the electrode film 60 formed in the first region R1 is separated by an electrode film slit 60b different from the slit 41. Specifically, six electrode film slits 60b are formed, and a virtual shape (hereinafter, also simply referred to as a virtual shape) KS formed by connecting predetermined positions in each electrode film slit 60b is formed to be hexagonal. More specifically, the electrode film slit 60b is formed such that a virtual shape formed by connecting the portions where each electrode film slit 60b intersects the outer shape of the electrode film 60 is hexagonal.

[0102] Note that the outer shape of the portion of the electrode film 60 located in the first region R1 here is, as described above, the shape formed by the outer shape line of the portion of the electrode film 60 located in the first region R1 and the extension line of the outer shape line.

[0103] Hereinafter, the reason why the virtual shape KS of the electrode film 60 is hexagonal will be described. As described above, the electrode film 60 and the piezoelectric film 50 are laminated and arranged in the order of the lower electrode film 61, the lower piezoelectric film 51, the intermediate electrode film 62, the upper piezoelectric film 52, and the upper electrode film 63. When forming the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63, after forming a metal film, the metal film is patterned into a desired shape by dry etching or the like using a mask. At this time, although a mask is used, the underlying lower piezoelectric film 51 and upper piezoelectric film 52 may be etched. In this case, when the piezoelectric film 50 is made of ScAlN, it has a hexagonal crystal structure. Therefore, by making the virtual shape KS of the electrode film 60 hexagonal, it is possible to suppress the crystal structure of the piezoelectric film 50 from collapsing when the surface of the piezoelectric film 50 is etched. That is, by matching the portion where the electrode film slit 60b is formed to the crystal structure of the piezoelectric film 50, it is possible to suppress fluctuations in the characteristics of the piezoelectric film 50.

[0104] Then, as shown in FIG. 23, the piezoelectric element 1 of the present embodiment has the capacitances between the electrode films 61 to 63 connected. In the present embodiment, as described above, the electrode film 60 is divided into six parts by the electrode film slit 60b different from the slit 41. Therefore, the piezoelectric element 1 of the present embodiment has six divided regions 226 and outputs a pressure detection signal based on the capacitance of each region 226.

[0105] Note that the electrode film 60 of the present embodiment is separated by the electrode film slit 60b as described above and is not separated by the slit 41. Therefore, as shown in FIG. 24, the electrode film 60 is in a connected state at the portion where the slit 41 is formed. Such a piezoelectric element 1 is manufactured, for example, by forming the slit 41 or the electrode film slit 60b every time each film is formed when performing the steps of FIGS. 4A and 4B. For example, after forming the base film 70, a metal film is formed on the base film 70. Then, when patterning the metal film to form the lower electrode film 61, the electrode film slit 60b is formed. Thereafter, the lower piezoelectric film 51 is formed on the lower electrode film 61, and before forming the intermediate electrode film 62, a slit 41 that penetrates only the lower piezoelectric film 51 may be formed in the lower piezoelectric film 51. Thereafter, the intermediate electrode film 62, the upper piezoelectric film 52, and the upper electrode film 63 are also formed in the same manner, whereby the piezoelectric element 1 of the present embodiment is manufactured.

[0106] Also, in the present embodiment, actually, the outer edge end portion on the side opposite to the central portion C is formed up to the outside of the first region R1, and the inner edge end portion is formed up to the inside of the second region R2. Therefore, when patterning the metal film into a desired shape to form the intermediate electrode film 62 and the upper electrode film 63 after forming the metal film, even if the piezoelectric film 50 is removed in a portion different from the electrode film slit 60b, the piezoelectric film 50 outside the first region R1 is removed. Therefore, by setting the virtual shape KS to a hexagonal shape, it is possible to suppress a decrease in detection accuracy.

[0107] Further, the virtual shapes KS of the vibration region 22 and the electrode film 60 are arranged to be point-symmetrical with respect to the central portion C. In the present embodiment, in the normal direction, the virtual shape KS of the electrode film 60 is hexagonal, and the outer shape of the vibration region 22 is octagonal. Then, the vibration region 22 and the electrode film 60 are arranged such that two opposite vertices in the virtual 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 virtual shape KS of the electrode film 60 are arranged on a virtual line K3 connecting two opposite vertices in the vibration region 22.

[0108] Furthermore, the piezoelectric element 1 (that is, the vibrating portion 20) of the present embodiment is rectangular in plan view as described above. Then, the virtual shapes KS of the vibration region 22 and the electrode film 60 are formed such that each corner is located at a portion different from the virtual line K2 connecting the opposite corners in the outer shape of the piezoelectric element 1.

[0109] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0110] (1) In the present embodiment, in the normal direction, the vibration region 22 and the electrode film 60 are arranged to be point-symmetrical with respect to the central portion C. Therefore, when sound pressure is applied to the vibration region 22, charges can be easily extracted evenly from the electrode film 60. Accordingly, it is possible to suppress a decrease in detection sensitivity and to suppress a decrease in detection accuracy.

[0111] (2) In this embodiment, the virtual shape KS of the vibration region 22 and the electrode film 60 is formed such that each corner is located at a portion different from the virtual line K2 connecting the opposing corner portions on the outer shape of the piezoelectric element 1. For this reason, it is possible to suppress a decrease in detection accuracy. That is, in the piezoelectric element 1, the portion that becomes the virtual line K2 connecting the opposing corner portions is likely to be distorted by thermal stress or the like. In this case, if the corner of the vibration region 22 or the corner of the virtual shape KS of the electrode film 60 is located on the virtual line K2, a large thermal stress is likely to be applied to the easily deformable corner, and the noise is likely to increase. Therefore, as in this embodiment, by positioning the corners of the vibration region 22 and the electrode film 60 at portions different from the virtual line K2, it is possible to suppress a decrease in detection accuracy.

[0112] (3) In this embodiment, the virtual shape KS of the electrode film 60 is hexagonal. For this reason, it is possible to suppress the crystallization of the piezoelectric film 50 from being disrupted when the electrode film 60 is patterned and configured. Therefore, it is possible to suppress fluctuations in the characteristics of the piezoelectric element 1.

[0113] (4) In this embodiment, the outer shape of the vibration region 22 is octagonal. For this reason, it is possible to suppress the concentration of strain at local portions of the vibration region 22.

[0114] (Modification of the Eighth Embodiment) A modification of the above-described seventh embodiment will be described. In the above-described seventh embodiment, if the vibration region 22 and the electrode film 60 are arranged to be point-symmetrical with respect to the central portion C, it is possible to easily extract charges evenly from the electrode film 60, similar to the above-described seventh embodiment. For this reason, for example, as shown in FIG. 25, the vibration region 22 and the electrode film 60 may be arranged such that a pair of opposing vertices of the electrode film 60 are located on the virtual line K1 connecting the center of a pair of opposing sides in the vibration region 22 and the central portion C. Note that even in such a configuration, it is preferable that the vibration region 22 and the electrode film 60 are formed such that each corner is located at a portion different from the virtual line K2. Also, in FIG. 25, as in FIG. 21, the illustration of the slit 41 is omitted.

[0115] Furthermore, in the sixth embodiment, similar to the modification of the first embodiment, the electrode film 60 may be divided into a plurality of charge regions 60a in the first region R1 as shown in FIG. 26. Then, as shown in FIG. 27, each of the divided charge regions 60a may be connected in series. When the electrode film 60 is configured in this way, the electrode film 60 may be formed by the slit 41 formed in the piezoelectric film 50.

[0116] (Ninth Embodiment) The ninth embodiment will be described. This embodiment defines the slit length and the like with respect to the first embodiment. Since the other aspects are the same as those of the first embodiment, the description is omitted here.

[0117] The piezoelectric device S10 of this embodiment is basically the same as that of the first embodiment and is configured as shown in FIG. 28. Note that FIG. 28 schematically shows the acoustic resistance Rg and the like, which will be described later. In this case, the sensitivity of the piezoelectric device S10 is expressed as 1 / {(1 / Cm)+(1 / Cb)}, where Cm is the acoustic compliance of the piezoelectric element 1 and Cb is the acoustic compliance of the back space S2. The acoustic compliance Cb is expressed by the following Equation 1.

[0118] [Equation] In Equation 1 above, Vb is the volume of the back space S2, ρ0 is the air density, and c is the speed of sound. The acoustic compliance Cb is proportional to the volume Vb of the back space S2. Therefore, the influence of the acoustic compliance Cb on the sensitivity becomes smaller as the back space S2 becomes smaller. Currently, miniaturization of the piezoelectric device S10 is desired, and the back space S2 also becomes smaller by miniaturizing the piezoelectric device S10. Therefore, the influence of the acoustic compliance Cm of the piezoelectric element 1 on the sensitivity of the piezoelectric device S10 becomes larger.

[0119] Here, in the piezoelectric element 1 as described above, it is desired to widen the frequency range in which the sensitivity can be maintained. For this reason, in the present embodiment, the low-frequency roll-off frequency is made smaller.

[0120] First, the low-frequency roll-off frequency fr is expressed by the following Equation 2, where the acoustic resistance (i.e., air resistance) due to the slit 41 is Rg.

[0121]

Equation

[0122]

Equation

[0123] And in order to make the low-frequency roll-off frequency fr 20 Hz or less outside the audible range, it is sufficient to satisfy the following Equation 4.

[0124]

Mathematics

[0125]

Mathematics

[0126]

Mathematics

[0127] Here, for example, when the thickness h of the vibration region 22 is 1 μm, as shown in FIG. 29, it is confirmed that the acoustic resistance Rg decreases as the average slit width ga increases and also decreases as the slit length L increases. Further, when the average slit width ga is 1 μm, as shown in FIG. 30, it is confirmed that the acoustic resistance Rg decreases as the thickness h of the vibration region 22 increases and also decreases as the slit length L increases. And as shown in FIG. 31, for example, taking the case where the slit length L at which the acoustic resistance is about 100 Hz is 700 μm as a reference, it is confirmed that the slit length L can be 20 Hz or less if it is about 150 μm.

[0128] Note that in FIG. 31, since the case where the slit length L is 700 μm is used as a reference, the acoustic resistance ratio when the slit length L is 700 μm is 1. Further, FIG. 31 shows that the volume of the back space S2 that affects the acoustic compliance Cb of the back space S2 is 4×10 -9 m 3 is used.

[0129] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0130] (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 back space S2 are formed so as to satisfy the above formula 6. Therefore, the low-frequency roll-off frequency fr can be set to 20 Hz or less, and the range in which the sensitivity can be maintained can be widened.

[0131] (Tenth Embodiment) The tenth embodiment will be described. This embodiment is different from the ninth embodiment in that the shape of the slit 41 is changed. Since the other aspects are the same as those of the ninth embodiment, the description thereof will be omitted here.

[0132] In the ninth embodiment described above, the configuration in which the slit width g gradually narrows along the thickness direction of the vibration region 22 has been described. However, the slit 41 may be configured such that the slit width g changes stepwise along the thickness direction of the vibration region 22. For example, as shown in FIG. 32, the slit width g may be changed in three steps. Specifically, in this embodiment, the slit 41 is formed such that the slit width g gradually widens in the order of g1, g2, and g3 from the other surface 22b side to the one surface 22a side of the vibration region 22. In this configuration, the angle formed between the line connecting the opening end of the slit 41 on the other surface 22b side and the opening end of the slit 41 on the one surface 22a side and the other surface 22b is the angle θ1.

[0133] In this case, the slit length L may be obtained using the average slit width ga, or may be obtained using the following formula 7. In the following formula 7, in the vibration region 22, the thickness of the portion where the slit width is g1 is defined as the thickness h1 of the vibration region 22, the thickness of the portion where the slit width is g2 is defined as the thickness h2 of the vibration region 22, and the thickness of the portion where the slit width is g3 is defined as the thickness h3 of the vibration region 22.

[0134]

Number

[0135] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0136] (1) In the present 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 back space S2 are formed so as to satisfy the above formula 7. For this reason, the low-frequency roll-off frequency fr can be set to 20 Hz or less, and the range in which the sensitivity can be maintained can be widened.

[0137] (11th Embodiment) The 11th embodiment will be described. This embodiment defines the shape of the joining member 2 with respect to the first embodiment. Since the other aspects are the same as those of the first embodiment, the description is omitted here.

[0138] In the piezoelectric device S10 of the present embodiment, as shown in FIG. 34, the joining member 2 has a rectangular outer shape with corners in the normal direction. The joining member 2 is joined to a portion of the other surface 11b of the support substrate 11 in the piezoelectric element 1 that is different from the corner portions of the piezoelectric element 1. In the present embodiment, in the normal direction, the joining member 2 is arranged such that each corner of the joining member 2 protrudes from the respective opposite side portions of the piezoelectric element 1. Further, the joining member 2 is arranged such that the corners of the joining member 2 are located at portions different from the virtual line K2 connecting the opposite corners of the outer shape of the piezoelectric element 1. Note that the joining member 2 of the present embodiment is configured using a joining sheet with a predefined outer shape.

[0139] Also, in the electrode film 60 and the vibration region 22 of the present embodiment, similar to the eighth embodiment, the electrode film 60 has a hexagonal shape and the vibration region 22 has a regular octagonal shape. The electrode film 60 and the vibration region 22 are arranged to be point-symmetrical with respect to the central portion C. Note that in FIG. 34, the slit 41 is omitted.

[0140] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effects as those of the first embodiment can be obtained.

[0141] (1) In the present embodiment, the joining member 2 is arranged at a portion different from the corner portions of the outer shape of the piezoelectric element 1. Therefore, it is possible to suppress the propagation of thermal stress from the printed circuit board 101 to the corner portions of the piezoelectric element 1 where deformation is likely to increase. Accordingly, it becomes difficult for the piezoelectric element 1 to be deformed by the propagated thermal stress, and it becomes difficult for the vibration region 22 to be deformed. Thereby, it is possible to suppress a decrease in detection sensitivity and improve detection accuracy.

[0142] (2) In this embodiment, the joining member 2 has a rectangular outer shape with corners. And the joining member 2 is arranged such that in the normal direction, the corners are located at portions different from those on the virtual line K2. For this reason, it is possible to suppress stress concentration at the corners of the joining member 2 due to the deformation of the piezoelectric element 1, and it is possible to suppress the occurrence of problems such as peeling of the joining member 2.

[0143] (Modification of the 11th Embodiment) A modification of the above 11th embodiment will be described. As shown in Fig. 35A, the joining member 2 may have an equilateral triangular shape in the normal direction, or as shown in Fig. 35B, it may have a regular octagonal shape in the normal direction. Also, although not particularly shown, the joining member 2 may have a regular hexagonal shape, a regular decagonal shape, etc. in the normal direction. And the joining member 2 may be arranged to protrude from the piezoelectric element 1 in the normal direction, or may be arranged only inside the piezoelectric element 1.

[0144] Also, the joining member 2 may be arranged as shown in Figs. 36A to 36C with reference to the through hole 101b formed in the printed circuit board 101. Note that Figs. 36A to 36C are plan views seen from the other surface 11b side of the support substrate 11 of the piezoelectric element 1 and the joining member 2. Also, in Figs. 36A to 36C, the vibration region 22 is omitted and shown, and the portion facing the through hole 101b is shown by a broken line. And in Figs. 36A to 36C, the recess 10a formed in the support substrate 11 has a shape that coincides with the through hole 101b in the normal direction.

[0145] For example, as shown in FIG. 36A, the joining member 2 may be annular so as to surround the through hole 101b in the normal direction. Further, as shown in FIG. 36B, the joining member 2 may be formed in a cross shape extending in one direction and a portion extending in a direction orthogonal to the one direction in the normal direction. And, as shown in FIG. 36C, the joining member 2 may be diamond-shaped in the normal direction. In FIG. 36B, the corner portions of the joining member 2 are located on the virtual line K2. However, even with such a configuration, since the joining member 2 is joined only to a portion different from the corner portion of the piezoelectric element 1, thermal stress is difficult to propagate to the corner portion of the piezoelectric element 1, and the same effect as in the above-described 11th embodiment can be obtained.

[0146] (12th Embodiment) The 12th embodiment will be described. In this embodiment, a protrusion is formed on the printed circuit board 101 as compared with the 1st embodiment. Since the other aspects are the same as those of the 1st embodiment, the description thereof will be omitted here.

[0147] In the piezoelectric device S10 of the present embodiment, as shown in FIG. 37, a protrusion 101c is formed on the printed circuit board 101. Specifically, the protrusion 101c has a shape that matches the outer shape of the joining member 2 and is constituted by a part of the printed circuit board 101. For example, the protrusion 101c of the present embodiment 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 portion of the piezoelectric element 1.

[0148] According to the present embodiment described above, since the angle θ1 formed by the vibration region 22 is 39 to 81°, the same effect as in the above-described 1st embodiment can be obtained.

[0149] (1) In this embodiment, a protrusion 101c is formed on the printed circuit board 101. Therefore, when applying and arranging the liquid bonding member 2, by applying the bonding member 2 on the protrusion 101c, the outer shape of the bonding member 2 bonded to the piezoelectric element 1 can be easily adjusted. Accordingly, a liquid bonding member 2 can also be used, and the selectivity of the bonding member 2 can be improved. In particular, when adjusting the shape of the bonding member 2 as in the 11th embodiment, the outer shape of the bonding member 2 can be easily adjusted.

[0150] (Modification of the 12th embodiment) A modification of the 11th embodiment described above will be explained. In the 12th embodiment, the protrusion 101c may be constituted by a member separate from the printed circuit board 101.

[0151] (Other embodiments) Although the present disclosure has been described in accordance with the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, and further, other combinations and forms including only one element, more than one element, or less than one element thereof, are also within the scope and spirit of the present disclosure.

[0152] For example, in each of the above embodiments, the vibrating portion 20 may have a configuration including at least one layer of piezoelectric film 50 and one layer of electrode film 60. Further, the piezoelectric element 1 may have a polygonal shape such as a pentagonal shape or a hexagonal shape instead of a rectangular planar shape.

[0153] Also, in each of the above embodiments, the floating region 21b of the vibrating portion 20 may not be divided into four vibrating regions 22, but may be divided into three or less vibrating regions 22, or may be divided into five or more vibrating regions 22.

[0154] Furthermore, in each of the above embodiments, the piezoelectric device S10 may be configured such that a through hole 102a is formed in the lid portion 102 as shown in FIG. 38. In this case, as shown in FIG. 38, the pressure receiving surface space S1 is the space on the one surface 22a side in the vibration region 22 of the casing 100, and the back space S2 is the space on the other surface 22b side in the vibration region 22 of the casing 100.

[0155] And, in each of the above embodiments, the slit 41 may not be formed so as to intersect at the center portion C, and the vibration region 22 may be in a state of being supported on both sides by the support region 21a. According to this, the resonance frequency of the piezoelectric element 1 can be increased, the frequency range capable of maintaining the detection sensitivity can be widened, and further improvement in detection accuracy can be achieved.

[0156] The above embodiments can also be combined as appropriate. For example, the second embodiment may be combined with the third to twelfth embodiments, and the slit 41 may be configured to have a tapered portion 42 and a constant portion 43. The fourth and fifth embodiments may be combined with the sixth to twelfth embodiments to change the shape of the boundary portion B between the concave portion 10a and the vibration portion 20. The sixth embodiment may be combined with the seventh to twelfth embodiments to change the arrangement positions of the first electrode portion 81 and the second electrode portion 82. The seventh embodiment may be combined with the eighth to twelfth embodiments, and the slit 41 may be tapered such that the slit width g becomes narrower toward the center portion C. The eighth embodiment may be combined with the ninth to twelfth embodiments to define the shapes and arrangements of the vibration region 22 and the electrode film 60. The ninth embodiment may be combined with the tenth to twelfth embodiments to define the slit length L and the like. The tenth embodiment may be combined with the tenth to twelfth embodiments, and the slit width g of the slit 41 may be changed along the thickness direction of the vibration region 22. The eleventh embodiment may be combined with the twelfth embodiment to define the arrangement location of the joining member 2. In addition, combinations of the above embodiments may be further combined with each other.

Explanation of Reference Numerals

[0157] 10 Support 20 Vibration part 21a Support area 22 Vibration area 22a One side 22b The other side 22c Side surface 41 Slit 42 Tapered part

Claims

1. A support (10), A piezoelectric film (50) disposed on the support and made of a material having a larger film stress than aluminum nitride, and an electrode film (60) connected to the piezoelectric film to extract charges generated by deformation of the piezoelectric film. The support has a supported region (21a) supported by the support, and a plurality of vibrating regions (22) connected to the supported region and floating from the support. A vibrating part (20) that outputs a pressure detection signal based on the charges. The plurality of vibrating regions are separated from each other by a slit (41). The slit is formed in a state where a tapered part (42) whose width becomes narrower from one surface (22a) side opposite to the support side in the vibrating region toward the other surface (22b) side opposite to the one surface is formed. The electrode film is disposed inside the slit in the normal direction to the one surface. A piezoelectric element in which an angle (θ1) formed by a side surface (22c) constituting the tapered part in the vibrating region and a surface (22b, Sv) parallel to the one surface is 39° or more and 80° or less.

2. The piezoelectric element according to claim 1, wherein an angle formed by a side surface constituting the tapered part and a surface parallel to the one surface is 63° or less.

3. The piezoelectric element according to claim 1 or 2, wherein an angle formed by a side surface constituting the tapered part and a surface parallel to the one surface is 45° or more.

4. A recess (10a) for floating the inner edge side in the vibrating part is formed in the support. The piezoelectric element according to any one of claims 1 to 3, wherein a boundary portion between an opening end of the recess and the vibrating part has a curved shape.

5. An underlayer film (70) is disposed between the support, the piezoelectric film, and the electrode film. The piezoelectric element according to claim 4, wherein a protective member (71) having a higher strength than the base film is disposed at a boundary portion between the base film and the recess. **Claim 6** The piezoelectric element according to any one of claims 1 to 5, wherein the slit has a tapered shape that is narrower toward an end portion (21e) side opposite to the support region side in the vibration region from the support region side. **Claim 7** The piezoelectric element according to any one of claims 1 to 6, wherein the vibration region and the electrode film are arranged in a point-symmetrical state with respect to the center portion (C) of the vibration region in the normal direction to the one surface. **Claim 8** The electrode film is divided into a plurality of the vibration regions by the slit, The piezoelectric element according to any one of claims 1 to 7, wherein the plurality of vibration regions are electrically connected in series in order. **Claim 9** The outer shape of the vibration portion is polygonal in the normal direction to the one surface, The piezoelectric element according to any one of claims 1 to 8, wherein at least one of the electrode film and the vibration region is polygonal having a corner portion, and the corner portion is located at a portion different from a virtual line (K2) connecting opposite corner portions in the outer shape of the vibration portion. **Claim 10** The vibration region includes a region on the support region side and a region including the center portion (C) as a first region (R1), and a region different from the first region is a second region (R2), The piezoelectric film is made of a material having a hexagonal crystal structure, The electrode film is divided by six electrode film slits (60b), and a virtual shape (KS) connecting predetermined locations in each of the electrode film slits within the first region is hexagonal in the normal direction to the one surface. The piezoelectric element according to any one of claims 1 to 9. **Claim 11** The support includes a support substrate (11) and an insulating film (12) disposed on the support substrate where the vibrating portion is arranged, and a recess (10a) for floating the vibration region is formed in the support substrate and the insulating film. The support substrate is composed of a silicon substrate. The piezoelectric element according to any one of claims 1 to 10, wherein the outer shape of the vibration region is a regular octagon in the normal direction with respect to the one surface.

12. A piezoelectric element according to any one of claims 1 to 11, and a casing (100) for housing the piezoelectric element. The piezoelectric device, wherein a through hole (101b) through which pressure is introduced in communication with the outside is formed in the casing at a position facing the other surface of the piezoelectric element.

13. The piezoelectric device according to claim 12, wherein the casing has a mounted member (101) on which the piezoelectric element is mounted and a lid portion (102) fixed to the mounted member in a state of housing the piezoelectric element.

14. In the space inside the casing, a space different from the pressure receiving surface space (S1) located between the through hole and the vibrating portion is defined as a back space (S2). Let the acoustic compliance of the back space be Cb, the thickness of the vibration region be h, the average slit width which is the average of the widths along the thickness direction of the slit be ga, the air resistance be μ, and the slit length along the side surface of the vibration region of the slit be L. Then, the length of the slit satisfies the following formula in the piezoelectric device according to claim 12 or 13. [Equation 1]

15. The piezoelectric device according to claim 14, wherein the length of the slit is 150 μm or less.

16. The piezoelectric element is mounted on the mounted member through a joining member (2) by the support, and the outer shape has a polygonal shape with corners in the normal direction with respect to the one surface. The piezoelectric device according to claim 13, wherein the joining member is disposed at a portion different from the corner portion in the normal direction.

17. The piezoelectric device according to claim 16, wherein the joining member has a polygonal outer shape having a corner portion in the normal direction, and the corner portion is located at a portion different from a virtual line (K2) connecting opposite corner portions in the outer shape of the piezoelectric element.

18. The piezoelectric element is mounted on the mounted member via a joining member (2) by the support body, A protrusion (101c) is formed in a portion of the mounted member where the joining member is disposed, The piezoelectric device according to claim 13, wherein the joining member is disposed on the protrusion.

19. A piezoelectric element according to any one of claims 1 to 11, A casing (100) for housing the piezoelectric element, A microphone in which a through hole (101b) through which pressure is introduced in communication with the outside is formed at a position facing the other surface of the piezoelectric element in the casing.

20. The microphone according to claim 19, wherein the casing has a mounted member (101) on which the piezoelectric element is mounted and a lid portion (102) fixed to the mounted member in a state of housing the piezoelectric element.

21. A space different from a pressure receiving surface space (S1) located between the through hole and the vibrating portion in the space within the casing is defined as a back space (S2). When the acoustic compliance of the back space is Cb, the thickness of the vibrating region is h, the average slit width which is the average of the widths along the thickness direction of the slit is ga, the air resistance is μ, and the slit length along the side surface of the vibrating region of the slit is L, the length of the slit satisfies the following mathematical formula. The microphone according to claim 19 or 20. 【Equation 1】

22. The microphone according to claim 21, wherein the length of the slit is 150 µm or less.

23. The piezoelectric element is mounted on the mounted member via the joining member (2), and in the normal direction to the one surface, the outer shape is a polygon having corners. The microphone according to claim 20, wherein the joining member is disposed at a portion different from the corners in the normal direction.

24. The joining member has an outer shape that is a polygon having corners in the normal direction, and the corners are located at portions different from a virtual line (K2) connecting the opposing corners in the outer shape of the piezoelectric element. The microphone according to claim 23.

25. The piezoelectric element is mounted on the mounted member via the joining member (2). A protrusion (101c) is formed in a portion of the mounted member where the joining member is disposed. The microphone according to claim 20, wherein the joining member is disposed on the protrusion.

Images