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

Abstract

A piezoelectric element includes a support body, and a vibration portion (20) provided on the support body and configured to include a piezoelectric film and an electrode film connected to the piezoelectric film to extract electric charges generated by deformation of the piezoelectric film, the vibration portion having a support region (21a) supported by the support body and a plurality of vibration regions (22) connected to the support region (21a) and floating from the support body, the vibration portion outputting a pressure detection signal based on the electric charges. The electrode film is formed in a first region (R1). Furthermore, an improvement portion (22) that improves detection accuracy of the pressure detection signal is formed.

Description

[0001] Cross-reference of related applications

[0002] This application is incorporated herein by reference to the contents of Japanese Patent Application No. 2019-235224 filed on December 25, 2019, Japanese Patent Application No. 2020-125990 filed on July 24, 2020, Japanese Patent Application No. 2020-177170 filed on October 22, 2020, and International Application PCT / JP2020 / 040471 filed on October 28, 2020. Technical Field

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

[0004] Previously, piezoelectric elements in which the vibration region is cantilevered have been proposed (see, for example, Patent Document 1). Specifically, the vibration region is configured with a piezoelectric film and an electrode film connected to the piezoelectric film. Moreover, this piezoelectric element vibrates in the vibration region due to acoustic pressure (hereinafter, also referred to as sound pressure), thereby deforming the piezoelectric film and generating an electric charge on the piezoelectric film. Therefore, the sound pressure applied to the vibration region is detected by extracting the charge generated on the piezoelectric film via the electrode film.

[0005] Existing technical documents

[0006] Patent documents

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

[0008] However, there is a current expectation to improve detection accuracy in piezoelectric elements with such cantilevered vibration regions.

[0009] The purpose of this disclosure is to provide piezoelectric elements, piezoelectric devices, and methods for manufacturing piezoelectric elements that can improve detection accuracy.

[0010] According to one aspect of this disclosure, a piezoelectric element includes: a support body and a vibrating portion disposed on the support body. The vibrating portion is composed of a piezoelectric film and an electrode film connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film. The vibrating portion has a support region supported on the support body and multiple vibration regions connected to the support region and floating from the support body. The vibrating portion outputs a charge-based pressure detection signal. Each of the multiple vibration regions has one end of its boundary with the support region designated as a fixed end and the other end designated as a free end. The region on one end side is designated as a first region and the region on the other end side is designated as a second region. The electrode film is formed in the first region. The piezoelectric element has an improving portion that improves the detection accuracy of the pressure detection signal.

[0011] Therefore, since an enhancement section is formed to improve the accuracy of the pressure detection signal, the detection accuracy can be improved.

[0012] Furthermore, according to another aspect of this disclosure, the piezoelectric element comprises: a support body and a vibrating part disposed on the support body, having a piezoelectric film and an electrode film connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film. The vibrating part has a support region supported on the support body and a plurality of vibration regions connected to the support region and floating from the support body. The vibrating part outputs a charge-based pressure detection signal. The plurality of vibration regions each have one end that forms a boundary with the support region as a fixed end and the other end as a free end. The region on the one end side is designated as a first region and the region on the free end side is designated as a second region. Moreover, the resonant frequencies of the vibration regions, which are formed as at least a portion of each other, are different. The electrode film is disposed in the first region.

[0013] Therefore, since at least some of the vibration regions have different resonant frequencies, the relationship between frequency and sensitivity becomes a distinct waveform. Thus, by appropriately switching the vibration region used for pressure detection, a wider frequency band can be used to increase detection sensitivity; for example, the detection sensitivity for low-frequency noise such as road surface noise can also be improved. Therefore, improved detection accuracy can be achieved.

[0014] Furthermore, according to another aspect of this disclosure, the piezoelectric device includes the aforementioned piezoelectric element and a housing, having a mounting component that houses the piezoelectric element and a cover portion that is fixed to the mounting component in a manner that accommodates the piezoelectric element, wherein the housing is formed with a through hole that communicates with the outside to introduce pressure.

[0015] Therefore, since the piezoelectric device is equipped with a piezoelectric element with a lifting section, the accuracy of the pressure detection signal can be improved.

[0016] Furthermore, according to another aspect of this disclosure, the manufacturing method of a piezoelectric element includes the following steps: preparing a support body and forming a vibrating part on the support body; in the step of forming the vibrating part, a recess is formed on the support body to make the vibrating area float.

[0017] Therefore, since piezoelectric elements with raised sections can be manufactured, piezoelectric elements that can achieve improved detection accuracy can be manufactured.

[0018] In addition, the parenthesized reference numerals attached to each constituent element, etc., indicate an example of the correspondence between the constituent element, etc., and the specific constituent elements, etc., described in the embodiments described later. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the piezoelectric element in the first embodiment.

[0020] Figure 2 yes Figure 1 The diagram shows a plan view of the piezoelectric element.

[0021] Figure 3 This is a plan view of the piezoelectric element in a variation of the first embodiment.

[0022] Figure 4 This is a plan view of the piezoelectric element in the second embodiment.

[0023] Figure 5 This is a plan view of the piezoelectric element in the third embodiment.

[0024] Figure 6 This is a plan view of the piezoelectric element in the fourth embodiment.

[0025] Figure 7 This is a cross-sectional view of the piezoelectric element in the fifth embodiment.

[0026] Figure 8 This is a plan view of the piezoelectric element in the sixth embodiment.

[0027] Figure 9 This is a plan view of the piezoelectric element in the seventh embodiment.

[0028] Figure 10 It is a graph used to illustrate the relationship between the frequency and sensitivity of each sensor detection unit.

[0029] Figure 11 This is a cross-sectional view of the piezoelectric element in the eighth embodiment.

[0030] Figure 12 This is a cross-sectional view of the piezoelectric element in the ninth embodiment.

[0031] Figure 13A It means Figure 12 The diagram shows a cross-sectional view of the manufacturing process of the piezoelectric element.

[0032] Figure 13B It means Figure 13A Cross-sectional view of the subsequent manufacturing process of the piezoelectric element.

[0033] Figure 14 This is a cross-sectional view of the piezoelectric device in the ninth embodiment.

[0034] Figure 15 This is a graph showing the relationship between Cb / Cm and the sensitivity ratio.

[0035] Figure 16 This is a plan view of the piezoelectric element in the tenth embodiment.

[0036] Figure 17 This is a cross-sectional view of the piezoelectric device in the tenth embodiment.

[0037] Figure 18 It is a circuit diagram showing the connection relationship between the sensing and detection unit, parasitic capacitance, and circuit board.

[0038] Figure 19 This is a plan view showing the shape of the intermediate electrode film in the eleventh embodiment.

[0039] Figure 20 This is a plan view showing the shape of the intermediate electrode film in a modified example of the eleventh embodiment.

[0040] Figure 21 This is a diagram showing the stress distribution of the piezoelectric element in the twelfth embodiment.

[0041] Figure 22 This is a plan view of the piezoelectric element in the twelfth embodiment.

[0042] Figure 23 It is a diagram used to illustrate the concept of electrostatic energy in a vibration region.

[0043] Figure 24 Based on Figure 23 A schematic diagram showing the division of the vibration area into a first region and a second region.

[0044] Figure 25 This is a schematic diagram showing the vibration region in a modified example of the twelfth embodiment divided into a first region and a second region.

[0045] Figure 26 This is a diagram used to illustrate the concept of electrostatic energy in the vibration region of the thirteenth embodiment.

[0046] Figure 27 Based on Figure 26A schematic diagram showing the division of the vibration area into a first region and a second region.

[0047] Figure 28 This is a cross-sectional view of the piezoelectric element in the fourteenth embodiment.

[0048] Figure 29 This is a circuit diagram for a piezoelectric device.

[0049] Figure 30A This is a schematic diagram showing the application of sound pressure to the vibrating area.

[0050] Figure 30B This is a schematic diagram showing the application of sound pressure to the vibrating area.

[0051] Figure 31 This is a circuit diagram of a piezoelectric device in a modified example of the fourteenth embodiment.

[0052] Figure 32 This is a cross-sectional view of the piezoelectric element in the fifteenth embodiment.

[0053] Figure 33 It is a cross-sectional view showing the manufacturing process of a piezoelectric element.

[0054] Figure 34 It is a cross-sectional view showing the manufacturing process of a piezoelectric element.

[0055] Figure 35 This is a cross-sectional view of the piezoelectric device in the sixteenth embodiment.

[0056] Figure 36 This is a plan view of the piezoelectric element in the sixteenth embodiment.

[0057] Figure 37 This is a circuit diagram of the piezoelectric device in the sixteenth embodiment.

[0058] Figure 38 It is a graph showing the relationship between frequency and resonance ratio in the vibration region.

[0059] Figure 39 This is a cross-sectional view of the piezoelectric element in the seventeenth embodiment.

[0060] Figure 40 This is a schematic diagram showing the application of load to the vibrating area.

[0061] Figure 41 It means and Figure 40 A schematic diagram of the stress on the corresponding side.

[0062] Figure 42 It means along Figure 40 A schematic diagram of the stress in the cross section of line XXXXII-XXXXII.

[0063] Figure 43A This is a graph showing the relationship between the number of electrode regions and sensitivity when the length of the vibration region in the eighteenth embodiment is 440 μm.

[0064] Figure 43B This is a graph showing the relationship between the number of electrode regions and sensitivity when the length of the vibration region in the eighteenth embodiment is 490 μm.

[0065] Figure 43C This is a graph showing the relationship between the number of electrode regions and sensitivity when the length of the vibration region in the eighteenth embodiment is 540 μm.

[0066] Figure 44 This is a cross-sectional view of the piezoelectric device in the nineteenth embodiment.

[0067] Figure 45 It is a graph showing the relationship between frequency and sensitivity.

[0068] Figure 46 It is a diagram showing the acoustic compliance of the rear space and its relationship with the necessary acoustic resistance.

[0069] Figure 47 This is a graph showing the relationship between acoustic resistance and the width of the separation slit.

[0070] Figure 48 It is a graph showing the relationship between the ratio of acoustic compliance of the rear space to the acoustic compliance of the pressure surface space and the signal intensity ratio. Detailed Implementation

[0071] Hereinafter, embodiments of the present disclosure will be described based on the accompanying drawings. Furthermore, in the various embodiments described below, the same reference numerals will be used to describe the same or equivalent parts.

[0072] (First Implementation)

[0073] Reference Figure 1 as well as Figure 2 The piezoelectric element 1 of the first embodiment will be described. Furthermore, the piezoelectric element 1 of this embodiment is preferably used, for example, in a microphone. Figure 1 Equivalent to along Figure 2 A cross-sectional view of line II in the diagram. Additionally, in... Figure 2 The first electrode portion 71 and the second electrode portion 72, which will be described later, are shown in the image, but are omitted from the translation. Furthermore, in relation to... Figure 2 In the corresponding figures, the first electrode portion 71 and the second electrode portion 72 are also shown in an appropriately omitted manner.

[0074] The piezoelectric element 1 of this embodiment includes a support body 10 and a vibrating part 20. The support body 10 has a support substrate 11 and an insulating film 12 formed on the support substrate 11. In addition, the support substrate 11 is made of, for example, a silicon substrate, and the insulating film 12 is made of an oxide film.

[0075] The vibrating section 20 constitutes a sensing and detection section 30 that outputs a pressure detection signal corresponding to pressure such as sound pressure, and the vibrating section 20 is disposed on the support body 10. Furthermore, a recess 10a is formed on the support body 10 for floating the inner edge side of the vibrating section 20. Therefore, the vibrating section 20 is configured to have a support region 21a disposed on the support body 10, and a floating region 21b connected to the support region 21a and floating on the recess 10a. Additionally, the shape of the opening end (hereinafter referred to simply as the opening end of the recess 10a) on the vibrating section 20 side of the recess 10a is a planar rectangular shape. Therefore, the floating region 21b is a planar approximately rectangular shape.

[0076] Furthermore, in this embodiment, the floating region 21b is divided by a separation slit 41 and a stress-increasing slit 42 to form four vibration regions 22. In this embodiment, two separation slits 41 are formed, extending from approximately the center of the floating region 21b to opposite corners of the floating region 21b. However, in this embodiment, the separation slits 41 terminate within the floating region 21b. Moreover, as will be described in detail later, the floating region 21b is divided into four vibration regions 22 by being connected to the separation slits 41 via the stress-increasing slits 42 and extending to the end of the support region 21a side within the floating region. In addition, although not particularly limited, in this embodiment, the interval between each vibration region 22 (i.e., the width of the separation slits 41) is set to approximately 1 μm.

[0077] Furthermore, each vibration region 22 is constructed by being divided by the floating region 21b as described above. Therefore, one end 22a is designated as a fixed end supported by the support body 10 (i.e., the support region 21a), and the other end 22b is designated as a free end. That is, each vibration region 22 is connected to the support region 21a and is cantilevered. In addition, one end 22a of each vibration region 22 refers to the portion that coincides with the opening end of the recess 10a in the normal direction (hereinafter, it will only be referred to as the normal direction) relative to the surface direction of the vibration part 20, and is the portion that forms the boundary with the support region 21a. Therefore, the shape of one end 22a of each vibration region 22 depends on the shape of the opening end of the recess 10a.

[0078] The vibrating section 20 is configured to have a piezoelectric film 50 and an electrode film 60 connected to the piezoelectric film 50. Specifically, the piezoelectric film 50 has a lower piezoelectric film 51 and an upper piezoelectric film 52 stacked on the lower piezoelectric film 51. Furthermore, the electrode film 60 has a lower electrode film 61 disposed below the lower piezoelectric film 51, an intermediate electrode film 62 disposed between the lower piezoelectric film 51 and the upper piezoelectric film 52, and an upper electrode film 63 disposed on the upper piezoelectric film 52. That is, the vibrating section 20 is configured such that 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. The piezoelectric film 50 is formed by sputtering or the like.

[0079] Furthermore, each vibration region 22 has a fixed end side designated as the first region R1 and a free end side designated as the second region R2. A lower electrode film 61, an intermediate electrode film 62, and an upper electrode film 63 are formed in the first region R1 and the second region R2, respectively. However, the lower electrode film 61, intermediate electrode film 62, and upper electrode film 63 formed in the first region R1 are separated from those formed in the second region R2, becoming insulated. Furthermore, the lower electrode film 61, intermediate electrode film 62, and upper electrode film 63 formed in the first region R1 extend appropriately into the support region 21a.

[0080] A first electrode portion 71, 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 72, electrically connected to the intermediate electrode film 62 formed in the first region R1, are formed in the support region 21a of the vibration section 20. Additionally, Figure 1 It is along Figure 2 The cross-sectional view along line II in the paper shows different cross-sections of the vibration region 22 on the left and the vibration region 22 on the right. Furthermore, a first electrode portion 71 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 72 electrically connected to the intermediate electrode film 62 formed in the first region R1 are respectively formed in the support region 21a.

[0081] The first electrode portion 71 has a through electrode 71b, which is formed in a hole 71a that passes through the upper electrode film 63, the upper piezoelectric film 52, and the lower piezoelectric film 51, exposing the lower electrode film 61, and is electrically connected to both the lower electrode film 61 and the upper electrode film 63. Furthermore, the first electrode portion 71 has a pad portion 71c formed on the through electrode 71b and electrically connected to it. The second electrode portion 72 has a through electrode 72b, which is formed in a hole 72a that passes through the upper piezoelectric film 52, exposing the intermediate electrode film 62, and is electrically connected to it. Furthermore, the second electrode portion 72 has a pad portion 72c formed on the through electrode 72b and electrically connected to it.

[0082] Furthermore, the sensing and detection unit 30 in this embodiment is configured to output a pressure detection signal as a change in charge in the four vibration regions 22. That is, the four vibration regions 22 are electrically connected in series. More specifically, each vibration region 22 is configured with a dual piezoelectric wafer structure, and the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in each vibration region 22 are connected in parallel, and the vibration regions 22 are connected in series with each other.

[0083] Furthermore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2 are not electrically connected to the respective electrode portions 71 and 72, and are in a floating state. Therefore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2 are not necessarily required, but in this embodiment, they are provided to protect the portions of the lower piezoelectric film 51 and the upper piezoelectric film 52 located in the second region R2.

[0084] Furthermore, in this embodiment, the lower piezoelectric film 51 and the upper piezoelectric film 52 are constructed using lead-free piezoelectric ceramics such as scandium aluminum nitride (ScAlN) and aluminum nitride (AlN). The lower electrode film 61, the intermediate electrode film 62, the upper electrode film 63, the first electrode portion 71, and the second electrode portion 72 are constructed using materials such as molybdenum, copper, platinum, platinum, and titanium.

[0085] The above describes the basic configuration of the piezoelectric element 1 in this embodiment. When sound pressure is applied to each vibration region 22 (i.e., the sensing and detection unit 30), the piezoelectric element 1 causes each vibration region 22 to vibrate. In this case, for example, when the vibration region 22 is displaced upwards at its other end 22b (i.e., the free end side), tensile stress is generated in the lower piezoelectric film 51, and compressive stress is generated in the upper piezoelectric film 52. Therefore, the sound pressure is detected by extracting this charge from the first electrode portion 71 and the second electrode portion 72.

[0086] At this time, the stress generated in the vibration region 22 (i.e., the piezoelectric film 50) is released at the free end side (i.e., the other end side), so the stress at the fixed end side is greater than that at the free end side. That is, at the free end side, less charge is generated, and the signal-to-noise ratio (SN ratio) is more likely to decrease. Therefore, in the piezoelectric element 1 of this embodiment, as described above, each vibration region 22 is divided into a first region R1 where stress is more likely to increase and a second region R2 where stress is more likely to decrease. Moreover, 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 71 and 72, and the charge generated in the lower piezoelectric film 51 and the upper piezoelectric film 52 located in the first region R1 is extracted. As a result, the influence of noise can be suppressed.

[0087] Furthermore, in this embodiment, each vibration region 22 is provided with a deformation-promoting structure that promotes the deformation of the piezoelectric film 50 located in the first region R1 when sound pressure is applied. Additionally, in this embodiment, the deformation-promoting structure corresponds to a lifting section.

[0088] In this embodiment, each vibration region 22 is provided with a stress-increasing slit 42 to increase the stress generated in the first region R1 when sound pressure is applied. Specifically, the stress-increasing slit 42 is formed to connect with the separation slit 41 in the first region R1, and the connection with the separation slit 41 forms a corner C1. Therefore, the vibration region 22 is in a state where the portion floating from the support 10 in the first region R1 forms a corner C1, and stress tends to concentrate at the corner C1 and tends to increase. As a result, the stress generated at one end 22a of the vibration region 22 also increases, and the overall deformation increases. Therefore, the pressure detection signal can be increased by increasing the deformation of the piezoelectric film 50, and the detection sensitivity can be improved. In addition, the angle formed between the separation slit 41 and the stress-increasing slit 42 at the corner C1 formed by the connection between the separation slit 41 and the stress-increasing slit 42 can be an acute angle, an obtuse angle, or a right angle.

[0089] In the embodiment described above, the vibration region 22 has a corner C1 formed in the portion of the first region R1 that floats from the support 10. Furthermore, stress tends to concentrate and increase in this corner C1. Therefore, deformation of the first region R1 in the vibration region 22 can be promoted, thereby increasing the pressure detection signal. Consequently, detection sensitivity and detection accuracy can be improved.

[0090] However, as described above, in the cantilevered vibration region 22, one end 22a supported by the support body 10 is restrained by the support body 10. Therefore, the stress generated in the vibration region 22 tends to be greatest in a region slightly offset towards the inner edge of the end 22a. However, by forming a corner C1 in the vibration region 22 as described above, it is also possible to offset the region where the stress is greatest towards the end 22a. Therefore, in this embodiment, the overall deformation of the vibration region 22 can be increased, thereby improving the detection sensitivity.

[0091] (A variation of the first embodiment)

[0092] A variation of the first embodiment described above will be described. In the first embodiment described above, as... Figure 3 As shown, the stress-increasing slit 42 may also extend along the extension direction of the separation slit 41, and be bent in shape only at the corner C1 of the stress-increasing slit 42. That is, the stress-increasing slit 42 may also be in a so-called wave shape.

[0093] Furthermore, the stress-increasing slit 42 can also be configured such that if the stress generated at the corner C1 formed by the stress-increasing slit 42 becomes too large and may damage the vibrating part 20, the corner C1 is provided to have a curved shape with curvature.

[0094] (Second Implementation)

[0095] The second embodiment will be described. In this embodiment, the configuration of the deformation-promoting structure is changed compared to the first embodiment. All other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0096] In this embodiment, such as Figure 4 As shown, instead of a stress-increasing gap 42, a separation gap 41 is formed in the vibration region 22, extending to the corner of the floating region 21b. That is, in this embodiment, the floating region 21b is divided into four vibration regions 22 only by the separation gap 41. Furthermore, in each vibration region 22, a corner C2 is formed at one end 22a. In this embodiment, the corner C2 corresponds to a deformation-promoting structure.

[0097] Specifically, in this embodiment, the opening end of the recess 10a in the support body 10, in the portion between the two ends of one end 22a of the vibration region 22, has a recess 10b that recesses the opening end toward the outer edge of the support body 10. In other words, the two ends of one end 22a of the vibration region 22 refer to the portion reached by the separation slit 41 in one end 22a.

[0098] Furthermore, the opening end of the recess 10a is formed with an uneven structure by the recess 10b along the direction of the opening end. As a result, one end 22a of the vibration region 22 is formed with an uneven structure depending on the shape of the opening end of the recess 10a, and thus becomes a state in which a corner C2 is formed.

[0099] In the embodiment described above, the vibration region 22 forms a corner C2 at one end 22a, thus increasing the stress at that end 22a. Therefore, deformation near the corner C2 of the end 22a in the vibration region 22 can be promoted, thereby increasing the pressure detection signal. Thus, improved sensitivity can be achieved.

[0100] (A variation of the second embodiment)

[0101] A variation of the second embodiment described above will be described. In the second embodiment, the corner C2 may also be formed in the opening end of the recess 10a by forming a protrusion that protrudes towards the inner edge of the support 10. That is, in the second embodiment, as long as the corner C2 is formed in the first region R1, i.e., one end 22a, in the vibration region 22, the shape of the opening end side of the recess 10a can be appropriately modified.

[0102] Furthermore, in the second embodiment, as in the variation of the first embodiment described above, if the stress generated at the corner C2 becomes too large and may damage the vibrating part 20, the corner C2 may be made into a curved shape with curvature.

[0103] (Third Implementation)

[0104] The third embodiment will be described. In this embodiment, the configuration of the deformation-promoting structure is changed compared to the first embodiment. All other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0105] In this embodiment, such as Figure 5 As shown, the opening end of the recess 10a formed in the support 10 is a planar circular shape centered at the intersection of the two separation gaps 41. Furthermore, the opening end of the recess 10a is formed to intersect the two ends in the normal direction with the two ends in the extension direction of the stress-increasing gap 42.

[0106] Therefore, the two ends of the support region 21a side on the outline of the floating region in the vibration region 22 reach one end 22a. Furthermore, the vibration region 22 has a shape with one end 22a bulging towards the side opposite to the other end 22b, relative to the virtual line K1 connecting the two ends. In this embodiment, the opening end of the recess 10a is a planar circle, therefore one end 22a of the vibration region 22 is an arc shape. Therefore, compared to the first embodiment described above, where the opening end of the recess 10a is rectangular and one end 22a aligns with the virtual line K1, the first region R1 of each vibration region 22 in this embodiment is larger.

[0107] Furthermore, the outline of the vibration region 22 refers to the line at the end forming the outline of the vibration region 22. Moreover, the outline of the floating region within the vibration region 22 refers to the line of the outline of the vibration region 22 excluding the portion supported by the end 22a of the support body 10. Additionally, in this embodiment, the shape of the end 22a corresponds to a deformation-promoting structure.

[0108] In the embodiment described above, the vibration region 22 is shaped such that one end 22 bulges out to the opposite side of the other end 22b compared to the virtual line K1. Therefore, compared to the case where the opening end of the recess 10a is rectangular, the first region R1 can be increased. Furthermore, as described above, the vibration region 22 is more prone to deformation in the portion slightly inward of one end 22a, thus the deformation near the virtual line K1 can also be increased. That is, the deformation of the portion becoming one end 22a, when the opening end of the recess 10a is rectangular, can also be increased. Therefore, an increase in the pressure detection signal can be achieved, and improved sensitivity can be realized.

[0109] (Fourth Implementation)

[0110] The fourth embodiment will be described. This embodiment differs from the third embodiment in that the configuration of the deformation-promoting structure is modified. Other aspects are the same as the third embodiment, therefore, descriptions are omitted here.

[0111] In this embodiment, such as Figure 6 As shown, no stress-increasing gap 42 is formed in the vibration section 20. Furthermore, the opening end of the recess 10a formed in the support body 10 is a planar circular shape centered on the intersection of the two separation gaps 41. However, in this embodiment, the opening end of the recess 10a is formed so as not to intersect with the separation gaps 41.

[0112] That is, the two ends of the support region 21a side of the outline of the floating region in the vibration region 22 are respectively terminated in the floating region. Therefore, in this embodiment, each vibration region 22 is in a state where the portions of one end 22a side are connected to each other.

[0113] Furthermore, the vibration region 22 has a shape in which one end 22a bulges laterally relative to the virtual line K2 connecting the two ends, opposite to the other end 22b. Therefore, compared to the case in the first embodiment where the opening end of the recess 10a is set to a rectangular shape and one end coincides with the virtual line K2, the first region R1 of each vibration region 22 in this embodiment is larger. In addition, in this embodiment, the shape of one end 22a corresponds to a deformation-promoting structure.

[0114] In the embodiment described above, the vibration region 22 is configured to have a shape in which one end 22a bulges out toward the opposite side of the virtual line K2 and the other end 22b. Therefore, compared to the case where the opening end of the recess 10a is rectangular, the first region R1 can be increased. Thus, the same effect as the third embodiment described above can be obtained.

[0115] (Fifth Implementation)

[0116] The fifth embodiment will be described. This embodiment differs from the first embodiment in that the configuration of the deformation-promoting structure is modified. All other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0117] In this embodiment, such as Figure 7 As shown, a hole 81 is formed in the second region R2, which penetrates the upper electrode film 63, the upper piezoelectric film 52, the intermediate electrode film 62, and the lower piezoelectric film 51 to reach the lower electrode film 61. Moreover, a hard film 82 with a higher Young's modulus than the piezoelectric film 50 is embedded (buried) in the hole 81.

[0118] In this embodiment, the hard film 82 is made of the same material as the first and second electrode portions 71, 72 or the electrode film 60. Furthermore, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2 are not electrically connected to the first and second electrode portions 71, 72, so there is no problem even if they are connected to each other. Moreover, in this embodiment, the hard film 82 corresponds to a deformation-promoting structure.

[0119] Furthermore, in this embodiment, the aperture 81 and the hard membrane 82 are formed to be denser at the other end 22b side in the second region R2 compared to the first region R1 side. More specifically, in this embodiment, the hard membrane 82 is formed in the second region R2 to gradually become denser from the first region R1 side to the other end 22b side.

[0120] As explained above, in this embodiment, a hard diaphragm 82 is disposed in the second region R2. Therefore, compared to the case where the hard diaphragm 82 is not disposed in the second region R2, the second region R2 is harder and therefore less prone to deformation when sound pressure is applied. Consequently, in this embodiment, stress tends to concentrate in the first region R1, making the first region R1 more prone to deformation. This results in an increase in the pressure detection signal and improved sensitivity.

[0121] Furthermore, in this embodiment, the hard membrane 82 is formed with a denser end 22b side in the second region R2 than in the first region R1. Therefore, for example, compared to the case where the hard membrane 82 is formed with a sparser end 22b side in the second region R2 than in the first region R1, deformation of the first region R1 can be prevented by the hard membrane 82. Thus, the effects of configuring the hard membrane 82 can be easily obtained.

[0122] Furthermore, the hard film 82 is made of the same material as the first and second electrode portions 71, 72 or the electrode film 60. Therefore, for example, the hard film 82 can be formed simultaneously with the formation of the first and second through electrodes 71b, 72b, which simplifies the manufacturing process.

[0123] (Sixth Implementation Method)

[0124] The sixth embodiment will be described. Compared to the first embodiment, this embodiment includes a temperature detection element and a heating element in each vibration region 22. Other aspects are the same as in the first embodiment, so descriptions are omitted here.

[0125] First, the piezoelectric element 1 described above is sometimes used in a state of exposure to external air or in a state of exposure to a specified oil. In this case, when the operating environment is low temperature, the vibration of the vibration region 22 may be hindered due to the freezing of the vibration region 22 caused by exposure to external air, or the reduced viscosity of the oil in contact with the vibration region 22. That is, the detection sensitivity of the piezoelectric element 1 described above may decrease when the operating environment is low temperature.

[0126] Therefore, in this embodiment, as Figure 8As shown, each vibration region 22 has a temperature sensing element 91 that outputs a temperature detection signal corresponding to the temperature, and a heating element 92 that heats up when energized. In this embodiment, in each vibration region 22, the temperature sensing element 91 and the heating element 92 are formed in the second region R2. More specifically, in this embodiment, the intermediate electrode film 62 is not formed in the second region R2. Moreover, the temperature sensing element 91 and the heating element 92 are formed in the portion located between the lower piezoelectric film 51 and the upper piezoelectric film 52. That is, the temperature sensing element 91 and the heating element 92 are formed in the portion where the intermediate electrode film 62 is formed in the first embodiment described above.

[0127] Furthermore, although not specifically illustrated, lead wires electrically connected to the temperature sensing element 91 and the heating element 92 are formed in the first region R1 and the support region 21a. Moreover, an electrode portion electrically connected to these lead wires is formed in the support region 21a. Thus, the connection between the temperature sensing element 91 and the heating element 92 and an external circuit can be achieved.

[0128] Furthermore, for the second region R2, the lower electrode film 61 and the upper electrode film 63 are formed in the same manner as in the first embodiment, sandwiching the piezoelectric film 50. Additionally, the temperature sensing element 91 is constructed using a temperature-sensitive resistor whose resistance changes with temperature, and the heating element 92 is constructed using a heating resistor that heats up when energized. In this embodiment, the temperature sensing element 91 and the heating element 92 are, for example, made of platinum. Furthermore, in this embodiment, the temperature sensing element 91 and the heating element 92 correspond to a raised portion.

[0129] In the embodiment described above, a temperature sensing element 91 and a heating element 92 are formed. Therefore, by adjusting the electrical current supplied to the heating element 92 based on the temperature detected by the temperature sensing element 91, the temperature of the vibration region 22 can be maintained at a predetermined temperature. Therefore, freezing of the vibration region 22 or a decrease in the viscosity of the oil in contact with the vibration region 22 can be suppressed, and a decrease in detection sensitivity can be suppressed. That is, a decrease in detection accuracy can be suppressed.

[0130] Furthermore, the temperature sensing element 91 and the heating element 92 are formed in the second region R2. Therefore, compared with the case where the temperature sensing element 91 and the heating element 92 are formed in the first region R1, the reduction of the portion of the intermediate electrode film 62 configured for charge extraction can be suppressed, and the second region R2 can be utilized effectively.

[0131] Furthermore, the temperature sensing element 91 and the heating element 92 are formed between the lower piezoelectric film 51 and the upper piezoelectric film 52, and are not exposed to the outside air. Therefore, the environmental resistance of the temperature sensing element 91 and the heating element 92 can be improved.

[0132] Furthermore, the temperature sensing element 91 and the heating element 92 are formed between the lower piezoelectric film 51 and the upper piezoelectric film 52, and the lower electrode film 61 and the upper electrode film 63 are formed in the same manner as in the first embodiment, sandwiching the piezoelectric film 50. Therefore, it is also possible to suppress the reduction of environmental resistance of the piezoelectric film 50.

[0133] (Seventh Implementation)

[0134] The seventh embodiment will be described. This embodiment has a plurality of sensing units 30 compared to the first embodiment. Other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0135] First, the piezoelectric element 1 described above has the potential to leak sound pressure through the parts used to divide each vibration region 22 (i.e., the separation slit 41 and the stress-increasing slit 42), and the acoustic impedance of the separation slit 41, which enters in parallel with the acoustic impedance, tends to decrease. Moreover, since the acoustic impedance decreases, the low-frequency roll-off frequency increases, and therefore the sensitivity at low frequencies tends to decrease.

[0136] Therefore, in this embodiment, as Figure 9 As shown, the piezoelectric element 1 is constructed by integrating multiple sensing and detection units 30 (i.e., floating regions 21b). Specifically, in the support body 10 of this embodiment, four recesses 10a are formed for floating the inner edge side of the vibrating unit 20. That is, the vibrating unit 20 of this embodiment has four floating regions 21b. Moreover, each floating region 21b is separated into four vibration regions 22 by forming separate separation gaps 41.

[0137] Furthermore, in this embodiment, the stress-increasing gap 42 is not formed. That is, in this embodiment, the separation gap 41 is formed at the corner reaching the floating region 21b.

[0138] Furthermore, in this embodiment, each vibration region 22 in each sensing unit 30 is configured with a different resonant frequency. In this embodiment, each vibration region 22 in each sensing unit 30 is formed such that the length between one end 22a and the other end 22b, i.e., the length of the beam, is different. Therefore, as... Figure 10 As shown, the relationship between frequency and sensitivity of each sensing unit 30 is represented by a different waveform for each sensing unit 30. Furthermore, in this embodiment, the configuration of vibration regions 22 with different resonant frequencies corresponds to an enhancement section.

[0139] In the embodiment described above, the piezoelectric element 1 is configured to have multiple sensing and detection units 30. Furthermore, each sensing and detection unit 30 is configured with a different resonant frequency, thus the relationship between frequency and sensitivity becomes a different waveform. Therefore, according to the piezoelectric element 1 of this embodiment, by appropriately switching the vibration region 22 used for sound pressure detection, the frequency range for which sensitivity is increased can be widened, for example, improving the detection sensitivity of low-frequency noise such as road noise.

[0140] Furthermore, the piezoelectric element 1 of this embodiment has a plurality of sensing units 30, which are supported on a common support body 10. Therefore, compared to the case where multiple piezoelectric elements 1 each have a single sensing unit 30, it is easier to narrow the spacing between adjacent sensing units 30. Here, for example, for a 20kHz sound wave, the wavelength is approximately 17mm. Therefore, by setting multiple sensing units 30 to be supported on a common support body 10 as in this embodiment, it is easy to arrange each sensing unit 30 with a spacing that is narrower than the wavelength. Therefore, sound pressure attenuation between each sensing unit 30 can be suppressed, and the reduction in detection sensitivity of sound pressure in the high-frequency region, which is prone to attenuation, can also be suppressed.

[0141] Furthermore, each vibration region 22 is configured with a different resonant frequency by varying the length between one end 22a and the other end 22b. Here, each vibration region 22 is formed by etching or the like of a floating region 21b. In this case, the length between one end 22a and the other end 22b can be easily changed by altering the etching mask. Therefore, according to this embodiment, it is possible to suppress the complexity of the manufacturing process and to easily form multiple vibration regions 22 with different resonant frequencies.

[0142] (Eighth Implementation Method)

[0143] The eighth embodiment will now be described. In this embodiment, compared to the first embodiment, a protective film is provided in the recess 10a of the support 10. All other aspects are the same as in the first embodiment, and therefore descriptions are omitted here.

[0144] First, the piezoelectric element 1 described above is formed in the recess 10a of the support 10 by etching. For example, the recess 10a is formed by repeatedly performing a wet etching process on the support 10, a process of forming a protective film to protect the wall surface after wet etching, and a process of further removing the wall surface after wet etching by dry etching. In this case, the recess 10a is prone to having fine unevenness on its side surface. Therefore, in the piezoelectric element 1 described above, turbulence may be generated due to the fine unevenness on the side surface of the recess 10a, leading to a decrease in detection sensitivity.

[0145] Therefore, in this embodiment, as Figure 11 As shown, a protective film 100 is formed on the support 10. This protective film 100 is embedded (embedded) in the portion of the recess 10a that becomes the side surface 10c, with minute irregularities. The exposed surface 100a on the opposite side of the recess 10a is flatter than the side surface 10c of the recess 10a. Furthermore, in this embodiment, the protective film 100 is also formed on the portion of each vibration region 22 on the support 10 side and on the portion of each vibration region 22 opposite to the adjacent vibration region 22.

[0146] In this embodiment, the protective film 100 is made of a material that is both water-repellent and oil-repellent, making it difficult for foreign objects such as water droplets and oil droplets to adhere. For example, it is made of a fluoropolymer. Furthermore, the protective film 100 is applied to the portion including the side surface 10c of the recess 10a by means of coating, dipping, or vapor deposition. Thus, the protective film 100 is configured such that the exposed surface 100a is flatter than the side surface 10c of the recess 10a.

[0147] Furthermore, the protective film 100 is preferably made of a material that does not easily impede the vibration of the vibration region 22. For example, when the piezoelectric film 50 is made of aluminum scandium nitride, the Young's modulus is about 250 GPa. Therefore, the protective film 100 is preferably made of a material with a Young's modulus of about 1 / 500 or less, and more preferably a material with a Young's modulus of about 0.1 to 0.5 GPa.

[0148] In the embodiment described above, a protective film 100 with an exposed surface 100a that is flatter than the side surface 10c of the recess 10a is disposed on the support 10. Therefore, turbulence generated in the recess 10a can be suppressed, and the reduction in detection accuracy can be suppressed.

[0149] Furthermore, a protective film 100 is also formed in the vibration region 22, and is made of a material that is both water-repellent and oil-repellent. Therefore, it can prevent foreign matter such as water from adhering to the protective film 100, and can also suppress turbulence caused by such foreign matter.

[0150] Furthermore, the protective film 100 is made of a material that does not easily impede the vibration of the vibration region 22. Therefore, by configuring the protective film 100, it is possible to suppress the vibration of the vibration region 22 and suppress the reduction of detection sensitivity.

[0151] (Ninth Implementation)

[0152] The ninth embodiment will be described. This embodiment differs from the first embodiment in that the shape of the support 10 is changed. Other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0153] In this embodiment, the support substrate 11 is constructed from a silicon substrate as described above, having a side 11a on the side of the insulating film 12 and another side 11b opposite to side 11a. Furthermore, as... Figure 12 As shown, the support substrate 11 has a recessed structure on its side surface 11c, which forms the recess 10a. Furthermore, in this embodiment, the recessed structure of the side surface 11c corresponds to a raised portion.

[0154] Specifically, the side surface 11c of the support substrate 11 is configured as follows: First, the opening on the side opposite to the insulating film 12 is designated as the first opening 11d, and the opening on the insulating film 12 side is designated as the second opening 11e. In this case, the side surface 11c is a structure in which a first tapered portion 11f, cut from the first opening 11d toward the second opening 11e, is connected to a second tapered portion 11g, cut from the second opening 11e toward the first opening 11d. That is, the side surface 11c of the support substrate 11 is a structure in which the portion between the first opening 11d and the second opening 11e is recessed relative to the virtual line K3 connecting the first opening 11d and the second opening 11e.

[0155] In this embodiment, one side 11a and the other side 11b of the support substrate 11 are (100) surfaces, and the first opening 11d and the second opening 11e are rectangular. Furthermore, the first cone 11f and the second cone 11g are (111) surfaces.

[0156] Furthermore, the piezoelectric element 1 in this embodiment, as in the seventh embodiment described above, does not have a stress-increasing gap 42 formed. That is, in this embodiment, the separation gap 41 is formed at the corner reaching the floating region 21b. Moreover, in the embodiments described later, examples without a stress-increasing gap 42 will be presented. However, in this embodiment and the embodiments described later, a stress-increasing gap 42 may be appropriately formed.

[0157] The above describes the configuration of the piezoelectric element 1 in this embodiment. Next, referring to... Figure 13A as well as Figure 13B The manufacturing method of the piezoelectric element 1 described above will be explained.

[0158] First, such as Figure 13A As shown, an insulating film 12 is prepared to be disposed on a support substrate 11, and a piezoelectric film 50, an electrode film 60, a first electrode portion 71, a second electrode portion 72, etc., are formed on the insulating film 12. Furthermore, the support substrate 11 is constructed of a silicon substrate, with one side 11a and the other side 11b being (100) surfaces. Moreover, the piezoelectric film 50, the electrode film 60, the first electrode portion 71, the second electrode portion 72, etc., are formed by appropriately performing conventional sputtering, etching, or other methods.

[0159] Furthermore, using a mask (not shown), anisotropic dry etching is performed to penetrate the insulating film 12 from the other side 11b of the support substrate 11. Additionally, after this process, the side surface 11c of the support substrate 11 coincides with the virtual line K3 connecting the first opening 11d and the second opening 11e.

[0160] Next, as Figure 13B As shown, anisotropic wet etching is performed on the side surface 11c of the support substrate 11 using a mask (not shown), thereby forming a recessed structure on the side surface 11c of the support substrate 11. Specifically, the support substrate 11 is constructed of a silicon substrate, with one side 11a and the other side 11b designated as (100) surfaces. Therefore, by performing anisotropic wet etching, a first cone 11f and a second cone 11g are formed from the (110) surface, which has the slowest etching rate among the silicon surface orientations.

[0161] Subsequently, although not specifically illustrated, it is manufactured by appropriately forming a separation gap 41. Figure 12 The piezoelectric element 1 shown.

[0162] In addition, such as Figure 14 As shown, the piezoelectric element 1 described above is housed in the housing 130 to form a piezoelectric device. Specifically, the housing 130 has a printed circuit board 131 and a cover 132. The printed circuit board 131 is equipped with the piezoelectric element 1 and a circuit board 120 for performing predetermined signal processing, etc. The cover 132 is fixed to the printed circuit board 131 to accommodate the piezoelectric element 1 and the circuit board 120. In this embodiment, the printed circuit board 131 corresponds to the mounted component.

[0163] Although not specifically illustrated, the printed circuit board 131 is configured to have wiring portions, through-hole electrodes, etc., and may also be equipped with electronic components such as capacitors (not shown) as needed. The other side 11b of the support substrate 11 of the piezoelectric element 1 is mounted on one side 131a of the printed circuit board 131 via a bonding member 2, such as an adhesive. The circuit board 120 is mounted on one side 131a of the printed circuit board 131 via a bonding member 121 formed of conductive components. Furthermore, the pad portion 72c of the piezoelectric element 1 is electrically connected to the circuit board 120 via a bonding wire 133. Additionally, the pad portion 71c of the piezoelectric element 1 is connected to... Figure 14 In different cross sections, it is electrically connected to the circuit board 120 via bonding lines 133. The cover portion 132 is made of metal, plastic, resin, etc., and is fixed to the printed circuit board 131 by bonding members such as adhesives (not shown) in a manner that accommodates the piezoelectric element 1 and the circuit board 120. Moreover, in this embodiment, a through hole 132a is formed in the portion of the cover portion 132 opposite to the sensing detection unit 30.

[0164] In this piezoelectric device, sound pressure (i.e., pressure) is applied to the sensing and detection section 30 through the through hole 132a and the space between the sensing and detection section 30 and the cover section 132, thereby detecting the sound pressure.

[0165] According to the embodiment described above, the support substrate 11 is provided with a recessed structure. Therefore, in the configuration of... Figure 14 With a piezoelectric device like the one shown, improved detection accuracy can be achieved.

[0166] That is, within the outer casing 130, the space between the portion forming the through-hole 132a that introduces sound pressure and the sensing unit 30 is designated as the pressure-bearing surface space S1. Furthermore, the space including the space located on the opposite side of the pressure-bearing surface space S1, separated by the sensing unit 30, and continuous with this space without being separated by the separation gap 41, is designated as the rear space S2. Additionally, the rear space S2 can be described as a space within the outer casing 130 that is different from the pressure-bearing surface space S1, or as a space other than the pressure-bearing surface space S1. In other words, the pressure-bearing surface space S1 can also be described as the space that influences the surface of the pressing vibration region 22 formed on the side of the through-hole 132a in the outer casing 130. The rear space S2 can also be described as the space that influences the surface of the pressing vibration region 22 on the side opposite to the side of the through-hole 132a in the outer casing 130.

[0167] In this case, the low-frequency roll-off frequency in this piezoelectric device is represented by 1 / (2π×Rg×Cb), with the acoustic resistance (i.e., air resistance) based on the separation gap 41 set as Rg and the acoustic compliance of the rear space S2 set as Cb. Therefore, to reduce the low-frequency roll-off frequency, either the acoustic resistance Rg or the acoustic compliance Cb of the rear space S2 can be increased.

[0168] Furthermore, in this embodiment, a recessed structure is formed in the support substrate 11, thus increasing the acoustic compliance by increasing the space of the rear space S2. Therefore, in the piezoelectric device of this embodiment, by reducing the low-frequency roll-off frequency, the detection sensitivity in the low-frequency band can be improved, and the detection accuracy can be improved.

[0169] Furthermore, the sensitivity of this piezoelectric device, when the acoustic compliance of the piezoelectric element 1 is set to Cm and the acoustic compliance of the rear space S2 is set to Cb, is expressed by 1 / {(1 / Cm)+(1 / Cb)}. Therefore, to increase the sensitivity, the acoustic compliance Cb can be increased, and the acoustic compliance Cb is proportional to the size of the rear space S2.

[0170] Furthermore, in this embodiment, a recessed structure is formed in the support substrate 11, thus increasing the capacitance by increasing the space of the rear space S2. Therefore, in the piezoelectric device of this embodiment, the detection accuracy can be improved by increasing the sensitivity.

[0171] Specifically, such as Figure 15 As shown, by increasing the acoustic compliance Cb of the rear space S2, the decrease in sensitivity ratio can be suppressed. In this case, if Cb / Cm is less than 2, the sensitivity ratio decreases sharply, but by forming a recessed structure, the decrease in sensitivity ratio can be slowed down. That is, forming a recessed structure on the support substrate 11 as described above is particularly effective for piezoelectric devices where Cb / Cm is less than 2. Furthermore, Figure 15 Based on the case where Cb / Cm is extremely large.

[0172] Furthermore, the support substrate 11 has a configuration where the side surface 11c has a first tapered portion 11f and a second tapered portion 11g. Therefore, for example, compared to the case where the side surface 11c is only composed of the second tapered portion 11g, the bonding area between the other side 11b of the support substrate 11 and the printed circuit board 131 can be increased. That is, according to this embodiment, the reduction in adhesion to the printed circuit board 131 can be suppressed, and the detection accuracy can be improved. In addition, the side surface 11c is only composed of the second tapered portion 11g, in other words, it means that the second tapered portion 11g is formed to the first opening 11d.

[0173] Furthermore, the side surface 11c of the support substrate 11 is configured as a (111) surface by anisotropic wet etching, thus suppressing shape deviations. Therefore, it is possible to suppress stress deviations generated in the vibration region 22 and suppress deviations in detection accuracy.

[0174] In addition, in this embodiment, the first opening 11d and the second opening 11e are described as rectangular, but the shapes of the first opening 11d and the second opening 11e can be appropriately changed. For example, one side 11a and the other side 11b of the support substrate 11 can be set as (110) surface, and the first opening 11d and the second opening 11e can be set as octagonal.

[0175] (Tenth Implementation)

[0176] The tenth embodiment will be described. This embodiment differs from the ninth embodiment in that the arrangement of the piezoelectric element 1 in the piezoelectric device is changed. Other aspects are the same as in the ninth embodiment, therefore, descriptions are omitted here.

[0177] In this embodiment, such as Figure 16As shown, the piezoelectric element 1 is configured to have eight pads 701 to 708 formed on the upper piezoelectric film 52. Specifically, two pads are configured as connection pads 701 and 702 that are electrically connected to the sensing unit 30. Furthermore, the connection pads 701 and 702 correspond to the pads 71c and 72c in the first embodiment described above. The remaining six pads are configured as dummy pads 703 to 708 that are not electrically connected to the sensing unit 30.

[0178] Furthermore, when viewed from the normal direction, the eight pads 701-708 are arranged symmetrically with respect to the center of the piezoelectric element 1. That is, the eight pads 701-708 are arranged symmetrically with reference to the center of a surface parallel to the surface direction of one side 11a of the support substrate 11. In other words, when the piezoelectric element 1 is mounted on the printed circuit board 131, the eight pads 701-708 are arranged symmetrically with reference to the center of a surface of the piezoelectric element 1 parallel to the surface direction of the printed circuit board 131. In addition, the connecting pads 701 and 702 are arranged close to each other.

[0179] The above describes the configuration of the piezoelectric element 1 in this embodiment. Furthermore, as... Figure 17 As shown, the piezoelectric device is configured such that a piezoelectric element 1 is flip-chip mounted on a printed circuit board 131. Specifically, each pad portion 701 to 708 of the piezoelectric element 1 is connected to the printed circuit board 131 via a bonding member 3 made of conductive components such as solder. Furthermore, the piezoelectric element 1 is arranged on the printed circuit board 131 such that the connecting pad portions 701 and 702 are located on the circuit board 120 side. Moreover, the connecting pad portions 701 and 702 of the piezoelectric element 1 are electrically connected to the circuit board 120 via a wiring portion 131c formed on the printed circuit board 131.

[0180] Furthermore, in this embodiment, the wiring section 131c is formed with the shortest possible connection between the pad sections 701 and 702 and the circuit board 120. In addition, in this embodiment, all pad sections 701 to 708 are electrically connected to the printed circuit board 131. That is, none of the pad sections 701 to 708 are in a floating state.

[0181] Furthermore, in this embodiment, a through-hole 131b is formed on the printed circuit board 131. Therefore, in this embodiment, sound pressure is applied to the sensing unit 30 through the through-hole 131b to detect the sound pressure. Therefore, in this embodiment, within the housing 130, the space between the portion where the through-hole 131b is formed and the sensing unit 30 is called the pressure-bearing surface space S1, and the space located on the opposite side of the pressure-bearing surface space S1, across the sensing unit 30, is called the rear space S2.

[0182] Furthermore, as described above, the rear space S2 includes a space located on the opposite side of the pressure-bearing surface space S1, separated by the sensing unit 30; it can also be described as a space that is continuous with this space without being separated by the separation gap 41. Therefore, in Figure 17 In such a piezoelectric device, the space includes the space located on the opposite side of the pressure surface space S1, separated by the sensing and detection unit 30, and the space around the piezoelectric element 1 which is not continuous with the space via the separation gap 41.

[0183] According to the embodiment described above, by reducing parasitic capacitance, it is possible to suppress the decrease in detection accuracy.

[0184] That is, such as Figure 18 As shown, when the overall capacitance of the sensing unit 30 is set as Co, and the parasitic capacitance formed between the piezoelectric element 1 and the circuit board 120 is set as Cp, the piezoelectric device is configured such that a parasitic capacitance Cp is disposed between the capacitor Co and the circuit board 120. Furthermore, when the parasitic capacitance Cp is large, the ratio of charge flowing from the sensing unit 30 to the parasitic capacitance Cp increases, resulting in decreased detection accuracy. Additionally, the parasitic capacitance Cp is the sum of the capacitance of the portion connecting the piezoelectric element 1 (i.e., the sensing unit 30) and the circuit board 120, or the capacitance generated inside the circuit board 120.

[0185] Therefore, in this embodiment, the piezoelectric element 1 is flip-chip mounted on the printed circuit board 131 and connected to the circuit board 120 via a wiring portion 131c formed on the printed circuit board 131. Furthermore, the piezoelectric element 1 is arranged on the printed circuit board 131 such that the connecting pads 701 and 702 are on the circuit board 120 side. Therefore, compared to the case where the piezoelectric element 1 and the circuit board 120 are connected via bonding wire 133, the wiring portion 131c connecting the piezoelectric element 1 and the circuit board 120 can be shortened more easily. Therefore, by reducing the parasitic capacitance Cp, it is possible to suppress the decrease in detection accuracy.

[0186] Furthermore, in this embodiment, the piezoelectric element 1 is flip-chip mounted on the printed circuit board 131, and a through-hole 131b is formed on the printed circuit board 131. Therefore, compared with the case where the through-hole 132a is formed in the cover portion 132 as in the ninth embodiment described above, the pressure-bearing surface space S1 can be reduced, and the air spring in the pressure-bearing surface space S1 can be increased. Therefore, the sound pressure dispersion guided from the through-hole 132a can be suppressed, and the detection accuracy can be improved by improving the detection sensitivity. Alternatively, in this embodiment, the through-hole 132a can also be formed in the cover portion 132 as in the ninth embodiment described above. As such a piezoelectric device, although it is difficult to reduce the pressure-bearing surface space S1, the parasitic capacitance Cp can be reduced.

[0187] Furthermore, in this embodiment, the pads 701 to 708 are arranged symmetrically with respect to the center of the piezoelectric element 1. Therefore, when the piezoelectric element 1 is flip-chip mounted, tilting of the piezoelectric element 1 relative to the printed circuit board 131 can be suppressed.

[0188] Furthermore, since the dummy pads 703-708 are not connected to the sensing unit 30, they can also be bonded to the printed circuit board 131 using adhesives or the like. However, by connecting the dummy pads 703-708 to the printed circuit board 131 using bonding members 3 such as solder, the dummy pads 703-708 can also be maintained at a predetermined potential. Therefore, compared to the case where the dummy pads 703-708 are in a floating state, unnecessary noise can be suppressed. In addition, by arranging the same material between each pad 701-708 and the printed circuit board 131, it is difficult for the piezoelectric element 1 to tilt. Therefore, it is preferable to arrange the same bonding member 3 between the dummy pads 703-708 and the printed circuit board 131. Alternatively, a bottom filler or the like can be provided instead of the dummy pads 703-708 to suppress the tilting of the piezoelectric element 1.

[0189] Furthermore, although in this embodiment, the piezoelectric element 1 can be tilted to suppress tilting, the dummy pads 703-708 may not be provided, for example. As such a piezoelectric device, although the piezoelectric element 1 is prone to tilting, the parasitic capacitance Rp can be reduced.

[0190] (Eleventh Implementation Method)

[0191] The eleventh embodiment will be described. This embodiment differs from the first embodiment in that the shape of the intermediate electrode film 62 is changed. Other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0192] In this embodiment, Figure 19 As shown, the intermediate electrode film 62 is divided into a first intermediate electrode film 62a formed in the first region R1 and a second intermediate electrode film 62b formed in the second region R2. Furthermore, the first intermediate electrode film 62a is further divided into multiple charge regions 620 and dummy regions 624 and 625. In this embodiment, the multiple charge regions 620 are provided as three charge regions 621 to 623. Therefore, the piezoelectric element 1 is configured such that in each vibration region 22, a capacitor is formed between the multiple charge regions 620 and the lower electrode film 61 and upper electrode film 63 opposite to the charge regions 620.

[0193] In addition, Figure 19The shape of the intermediate electrode film 62 located in the vibration region 22 is shown, but the intermediate electrode film 62 is also appropriately extended in the support region 21a. Furthermore, in this embodiment, the intermediate electrode film 62 divided into multiple charge regions 621 to 623 corresponds to the lifting portion.

[0194] Multiple charge regions 621-623 are each set to the same area. That is, the dummy regions 624 and 625 are constructed such that each charge region 621-623 has the same area. Moreover, although not specifically shown, the multiple charge regions 621-623 are interconnected in series in the portion located on the support region 21a via wiring or the like (not shown). Therefore, in each vibration region 22, multiple capacitors are connected in series. In contrast, the dummy regions 624 and 625 are not connected to the charge regions 621-623 and are set to a floating state.

[0195] Furthermore, although not specifically illustrated, the lower electrode film 61 and the upper electrode film 63 are respectively formed in a manner opposite to the first intermediate electrode film 62a and the second intermediate electrode film 62b.

[0196] According to the embodiment described above, the first intermediate electrode film 62a is divided into multiple charge regions 621 to 623. Furthermore, the multiple charge regions 621 to 623 are connected in series. Therefore, within a first region R1, multiple capacitors are connected in series, increasing the capacitance and thus improving detection sensitivity. In addition, the multiple charge regions 621 to 623 are set to have the same area. Therefore, the multiple capacitors constituting a first region R1 are equal to each other. Therefore, noise generated between the capacitors can be suppressed, and a decrease in detection accuracy can be suppressed.

[0197] In addition, in this embodiment, an example is described in which the first intermediate electrode film 62a is divided into three charge regions 621 to 623, but the charge regions 621 to 623 may also be two, or there may be more than four charge regions.

[0198] Furthermore, in this embodiment, an example of dividing the first intermediate electrode film 62a into multiple charge regions 621 to 623 has been described. However, the lower electrode film 61 and the upper electrode film 63 can also be divided into multiple charge regions and dummy regions. Moreover, the same effect can be obtained even if the lower electrode film 61 and the upper electrode film 63 are divided into multiple charge regions and dummy regions. However, as described above, when the intermediate electrode film 62 is disposed between the lower electrode film 61 and the upper electrode film 63, and the intermediate electrode film 62 is divided, only the intermediate electrode film 62 needs to be divided, thus simplifying the configuration.

[0199] (A variation of the eleventh embodiment)

[0200] A variation of the eleventh embodiment will be described. In the eleventh embodiment described above, as follows... Figure 20 As shown, charge regions 621 and 623 do not necessarily have to be rectangular. That is, as long as the three charge regions 621 to 623 are equal, the position and shape of the dummy regions 624 and 625 can be appropriately changed. Moreover, as long as the areas of the three charge regions 621 to 623 are equal, the dummy regions 624 and 625 do not necessarily have to be formed.

[0201] (Twelfth Implementation)

[0202] The twelfth embodiment will be described. This embodiment, compared to the first embodiment, specifies the division method of the first region R1 and the second region R2. Other aspects are the same as the first embodiment, therefore, descriptions are omitted here.

[0203] First, in the piezoelectric element 1 described above, when sound pressure is applied to the sensing and detection unit 30, it becomes... Figure 21 The stress distribution is as shown. Specifically, the stress tends to be highest near the center of one end 22a and gradually decreases towards the other end 22b. Therefore, in this embodiment, as... Figure 22 As shown, the first region R1 and the second region R2 are divided based on stress distribution.

[0204] The following describes the division method of the first region R1 and the second region R2 in this embodiment. Furthermore, the division method in this embodiment is particularly effective when the sensitivity output is represented by voltage. Firstly, to improve the sensitivity of the piezoelectric element 1, it is sufficient to increase the electrostatic energy E generated in the first region R1. Here, as... Figure 23 As shown, the direction along one end 22a of the vibration region 22 is defined as the Y direction, and the direction orthogonal to the Y direction is defined as the X direction. Furthermore, in the small virtual regions M formed by dividing the vibration region 22 along the X direction, the capacitance of the virtual region M is defined as C, and the average value of the stress generated in the virtual region M is defined as σ. Moreover, if the voltage generated in the virtual region M is defined as V, then the electrostatic energy E is obtained through 1 / 2 × C × V. 2 This is expressed as follows. Furthermore, the generated voltage V is proportional to the generated stress σ.

[0205] Therefore, in this embodiment, as Figure 23 as well as Figure 24 As shown, calculate C×σ for each virtual region M. 2 The largest region is defined by connecting the boundaries of all virtual regions M to form the largest region, thus dividing the first region R1 and the second region R2. In this case, as... Figure 24As shown, the calculation line connecting the calculated values ​​can be used as the boundary line to divide the first region and the second region R2, or the approximate line based on the calculation line can be used as the boundary line to divide the first region R1 and the second region R2.

[0206] Furthermore, in this embodiment, the division of the first region R1 and the second region R2 is equivalent to a lifting section. Additionally, in Figure 24 The example shown illustrates an instance where the length of one end 22a along the Y direction in the vibration region 22 is set to 850 μm, and the length from one end 22a to the other end 22b is set to 425 μm. In this case, the approximation is expressed by the following equation 1.

[0207] (Equation 1)Y=-0.0011X 2 +1.0387X-41.657

[0208] According to the embodiment described above, the first region R1 and the second region R2 are divided in such a way that the electrostatic energy E of the first region R1 increases. Therefore, it is possible to improve the detection sensitivity and the detection accuracy.

[0209] (A variation of the twelfth embodiment)

[0210] A variation of the twelfth embodiment described above will be described. The first region R1 and the second region R2 can also be as follows: Figure 25 The region is divided as shown. That is, since the vibration region 22 is designed as a planar triangular shape, the triangle can be divided into three equal parts by dividing one end 22a. The first region R1 and the second region R2 are divided by connecting the centroids C of the three triangles with the boundary lines at both ends of one end 22a. Even when the first region R1 and the second region R2 are divided as described above, this includes regions where the electrostatic energy E is higher due to the division of the first region R1 and the second region R2 by a region approximating the line in the twelfth embodiment described above. Therefore, it is possible to improve detection sensitivity and detection accuracy.

[0211] Furthermore, in the twelfth embodiment described above, an example of a planar triangular shape for the vibration region 22 was given, but the shape of the vibration region 22 can be appropriately changed. For example, the vibration region 22 can be either a planar rectangular shape or a planar fan shape. Even if the vibration region 22 is as described above, the same effect as in the twelfth embodiment can be obtained by dividing the first region R1 and the second region R2 in the same way as in the twelfth embodiment.

[0212] (Thirteenth Implementation Method)

[0213] The thirteenth embodiment will be described. This embodiment, compared to the twelfth embodiment, specifies the division method of the first region R1 and the second region R2. Other aspects are the same as in the twelfth embodiment, therefore, descriptions are omitted here.

[0214] The following describes the division method of the first region R1 and the second region R2 in this embodiment. Furthermore, the division method of this embodiment is particularly effective when the sensitivity output is represented by charge. In this embodiment, compared to the twelfth embodiment described above, the area of ​​the virtual region M is set as S, and the sum of the stresses generated in the virtual region M is set as σsum. Moreover, 1 / 2 × C × V 2 With S×(σsum / S) 2 Proportional. That is, 1 / 2 × C × V 2 It is proportional to the stress generated per unit area. Therefore, in this embodiment, as... Figure 26 as well as Figure 27 As shown, calculate (σsum) for each virtual region M. 2 / S becomes the largest region, and the first region R1 and the second region R2 are divided by connecting the boundary lines of the largest region among all virtual regions M. In this case, as Figure 27 As shown, the computational line connecting the calculated values ​​can be used as the boundary line to divide the first region and the second region R2, or the approximate line based on the computational line can be used as the boundary line to divide the first region R1 and the second region R2. Furthermore, in Figure 27 The example shown illustrates an instance where the length of one end 22a along the Y direction in the vibration region 22 is set to 850 μm, and the length from one end 22a to the other end 22b is set to 425 μm. In this case, the approximation is expressed by the following equation 2.

[0215] (Formula 2)Y=241.11

[0216] Thus, dividing the first region R1 and the second region R2 based on the stress generated per unit area can achieve the same effect as the twelfth embodiment described above.

[0217] (Fourteenth Implementation)

[0218] The fourteenth embodiment will be described. In this embodiment, compared to the first embodiment, each vibration region 22 is warped and connected in parallel. Other aspects are the same as in the first embodiment, therefore, descriptions are omitted here.

[0219] In this embodiment, such as Figure 28As shown, in the piezoelectric element 1, the other end 22b (i.e., the free end) of each vibration region 22 is set to a warped state. In this embodiment, the other end 22b of each vibration region 22 is set to be along the side opposite to the support substrate 11 side. In addition, the amount of warping in each vibration region 22 is set to be the same, for example, configured to be warped to be greater than or equal to the thickness of the piezoelectric film 50.

[0220] Furthermore, as described above, each vibration region 22 is configured as a double piezoelectric wafer structure with a lower piezoelectric film 51 and an upper piezoelectric film 52 stacked together, which can obtain Figure 29 The circuit configuration is shown. Furthermore, in the case of a piezoelectric device, each electrode film 60 in each vibration region 22 is connected in parallel with the circuit board 120. That is, in this embodiment, a pressure detection signal is output from each vibration region 22 to the circuit board 120. Additionally, in this embodiment, the vibration region 22 has a warped shape, and the output of the pressure detection signal from each vibration region 22 to the circuit board 120 corresponds to a raised portion.

[0221] The above describes the configuration of the piezoelectric element 1 in this embodiment. Furthermore, this piezoelectric element 1 is manufactured as follows: When the piezoelectric film 50 is formed on the insulating film 12 by sputtering or the like, a predetermined voltage is applied to the piezoelectric film 50 through the support substrate 11, and a predetermined residual stress is generated in the formed piezoelectric film 50. Then, a separation gap 41 is formed to separate each vibration region 22, and the residual stress causes the other end 22b of each vibration region 22 to warp, thereby manufacturing the piezoelectric element 1. Figure 28 The piezoelectric element 1 shown.

[0222] This piezoelectric element 1 outputs pressure detection signals from each vibration region 22 as described above. At this time, for example... Figure 30A As shown, when sound pressure is applied to each vibration region 22 from a direction consistent with the normal direction, the deformation of each vibration region 22 is equal, and the pressure detection signal output from each vibration region 22 is also equal. On the other hand, for example, Figure 30B As shown, when sound pressure is applied to each vibration region 22 from a direction intersecting the normal direction, the deformation in each vibration region 22 is different, and the pressure detection signal output from each vibration region 22 is different. That is, a pressure detection signal corresponding to the direction of the applied sound pressure is output from each vibration region 22. Therefore, in the piezoelectric element 1 of this embodiment, the direction of the applied sound pressure can also be detected. That is, the piezoelectric element 1 of this embodiment is configured to be directional.

[0223] In this embodiment, the vibration region 22 is set to a warped state. Therefore, the difference in deformation corresponding to the direction of the applied sound pressure tends to increase in each vibration region 22. Thus, it is also possible to achieve an improvement in sensitivity related to directivity.

[0224] According to the embodiment described above, the piezoelectric element 1 is arranged with each vibration region 22 in a warped state. Furthermore, when connected to the circuit board 120, each vibration region 22 is connected in parallel with the circuit board 120. Therefore, it is possible to possess directivity and to achieve an improvement in sensitivity related to directivity.

[0225] (A variation of the fourteenth embodiment)

[0226] A variation of the fourteenth embodiment will be described. For example... Figure 31 As shown, in the fourteenth embodiment described above, each vibration region 22 may be connected in parallel with the circuit board 120 and connected in series with each other.

[0227] (Fifteenth Implementation)

[0228] The fifteenth embodiment will be described. In this embodiment, compared to the first embodiment, a reflective film is formed in the vibration region 22. Other aspects are the same as in the first embodiment, therefore, descriptions are omitted here.

[0229] In this embodiment, such as Figure 32 As shown, in each vibration region 22, a reflective film 140 with a higher reflectivity than the piezoelectric film 50, electrode film 60, and pad portions 71c and 72c is formed on the outermost layer. In this embodiment, the reflective film 140 is formed on the upper electrode film 63. In other words, high reflectivity can also be interpreted as low absorptivity. Furthermore, in this embodiment, the reflective film 140 is made of a material with a lower Young's modulus than the piezoelectric film 50, such as a single-layer or multi-layer aluminum film. Moreover, the reflective film 140 is formed in the second region R2. Additionally, in this embodiment, the reflective film 140 corresponds to a lifting portion.

[0230] The above describes the structure of the piezoelectric element 1 in this embodiment. Next, the manufacturing method of the piezoelectric element 1 in this embodiment will be described.

[0231] When manufacturing the piezoelectric element 1, an insulating film 12, a piezoelectric film 50, an electrode film 60, a reflective film 140, etc., are sequentially formed and appropriately patterned on the support substrate 11. Furthermore, after the recess 10a is formed, a separation gap 41 is formed.

[0232] Next, in this embodiment, a merits / demerits determination is performed. Specifically, as follows: Figure 33As shown, a detection device 150 is prepared. This detection device 150 includes a laser source 151 that irradiates a laser beam L, and a detector 152 that detects the intensity of the received laser beam L. The detector 152 has a control unit (not shown) that performs threshold-based judgments. The control unit is composed of a microcomputer, etc., which includes a CPU and a storage unit composed of non-volatile storage media such as ROM, RAM, flash memory, and HDD. CPU is short for Central Processing Unit, ROM is short for Read Only Memory, RAM is short for Random Access Memory, and HDD is short for Hard Disk Drive. The storage media such as ROM are non-volatile storage media.

[0233] The intensity of the laser beam L received without warping in the vibration region 22 is stored as a threshold in the storage unit. Furthermore, the control unit compares the intensity of the laser beam L received by the detector 152 with the threshold to determine its quality.

[0234] Specifically, a reference plane T is defined as the surface along the normal direction of the reflective film 140 disposed in the vibration region 22, and a laser beam L is irradiated onto the reflective film 140 from a direction inclined relative to the reference plane T. Furthermore, the laser beam L reflected by the detector 152 is detected. Then, the detector 152 compares the intensity of the detected laser beam L with a threshold to determine its quality. For example, if the intensity of the detected laser beam L is less than 50% of the threshold, the detector 152 determines that the state of the vibration region 22 is abnormal. In this case, for example... Figure 34 As shown, if the warping of the vibration region 22 is too large to be detected by the detector 152, the state of the vibration region 22 is also determined to be abnormal. Furthermore, the laser beam L is preferably one with the highest reflectivity; for example, when the reflective film 140 is made of aluminum, a wavelength in the visible light region of 1 μm or less is preferred. Additionally, when the reflective film 140 is made of other metal films, a wavelength in the infrared region is also preferred.

[0235] According to the embodiment described above, since a reflective film 140 is disposed in the vibration region 22, the quality of the vibration region 22 can be determined. Therefore, it is possible to manufacture a piezoelectric element 1 that can suppress the reduction of detection accuracy. Furthermore, in this embodiment, the quality determination is performed by irradiating the reflective film 140 with a laser beam L, thus enabling non-contact quality determination.

[0236] Furthermore, the reflective film 140 is made of a material with a smaller Young's modulus compared to the piezoelectric film 50. Therefore, the deformation of the reflective film 140 that hinders the piezoelectric film 50 can be suppressed, and the reduction in detection accuracy can be suppressed.

[0237] Furthermore, the reflective film 140 is disposed in the second region R2. Therefore, it is possible to suppress the influence of the reflective film 140 on the first region R1, where stress is prone to increase in the vibration region 22.

[0238] Alternatively, this embodiment can also be applied to the fourteenth embodiment. In this case, the threshold used for determination is set to the intensity when the warp of the vibration region 22 becomes a desired value.

[0239] (Sixteenth Implementation)

[0240] The sixteenth embodiment will be described. This embodiment performs self-diagnosis when the piezoelectric device is configured as in the ninth embodiment. Other aspects are the same as in the ninth embodiment, therefore, descriptions are omitted here.

[0241] In the piezoelectric device of this embodiment, such as Figure 35 As shown, the other side 11b of the piezoelectric element 1, which is supported by the substrate 11, is mounted on one side 131a of the printed circuit board 131 via the bonding member 2. Furthermore, in this embodiment, compared with the tenth embodiment described above... Figure 17 Similar to the piezoelectric device described, a through-hole 131b is formed on the printed circuit board 131. Therefore, in this embodiment, sound pressure is detected by applying sound pressure to the sensing unit 30 through the through-hole 131b. Furthermore, in this embodiment, the space between the portion where the through-hole 131b is formed and the sensing unit 30 within the housing 130 is called the pressure-bearing surface space S1. In addition, the space located on the opposite side of the pressure-bearing surface space S1, separated by the sensing unit 30, and the space continuous with this space without being separated by the separation gap 41, is called the rear space S2.

[0242] In addition, in this embodiment, with Figure 35 The piezoelectric device constructed in that manner has been described as an example, but the following configuration can also be applied to piezoelectric devices constructed as in the ninth and tenth embodiments.

[0243] like Figure 36 as well as Figure 37 As shown, the piezoelectric element 1 of this embodiment has first to fifth pad portions 701 to 705 electrically connected to each vibration region 22. Furthermore, the first to fifth pad portions 701 to 705 correspond to pad portions 71c and 72c in the first embodiment described above. Moreover, the piezoelectric element 1 is similar to the piezoelectric element described in the variation of the fourteenth embodiment. Figure 31Similarly, each vibration region 22 is configured to be connected in parallel to the circuit board 120 via the first to fifth pad portions 701 to 705, and connected in series with each other.

[0244] The circuit board 120 performs prescribed signal processing, and in this embodiment, a control unit 120a is provided. Alternatively, the control unit 120a may be provided independently of the circuit board 120.

[0245] The control unit 120a is the same as the control unit in the fifteenth embodiment described above, and is composed of a microcomputer, etc., which includes a CPU, a storage unit composed of non-volatile storage media such as ROM, RAM, flash memory, and HDD, etc. Furthermore, the control unit 120a of this embodiment performs self-diagnosis of the piezoelectric device.

[0246] Specifically, in this embodiment, the control unit 120a determines an anomaly in the piezoelectric element 1. More specifically, the control unit 120a applies a predetermined voltage between the first pad portion 701 and the fifth pad portion 705, causing each vibration region 22 to vibrate using an anomaly determination signal. More specifically, the control unit 120a causes each vibration region 22 to vibrate normally at a frequency of sound pressure that can be applied to the vibration region 22 during actual sound pressure detection. In this embodiment, as... Figure 38 As shown, a vibration region 22 is formed with a resonant frequency of 13 kHz, and the frequency at which the sound pressure that can be applied to the piezoelectric element 1 is assumed to be a few kHz.

[0247] Therefore, the control unit 120a applies a predetermined voltage between the first pad portion 701 and the fifth pad portion 705 to cause each vibration region 22 to vibrate normally at a frequency of several kHz. Furthermore, in this embodiment, the resonant frequency is set to 13 kHz, and the frequency of the sound pressure that can be applied to the piezoelectric element 1 is assumed to be several kHz. Therefore, it can also be said that the control unit 120a applies a predetermined voltage between the first pad portion 701 and the fifth pad portion 705 to cause normal vibration at a frequency lower than the resonant frequency.

[0248] Therefore, when each vibration zone 22 is normal, a voltage division corresponding to a specified voltage is applied to the second to fourth pad sections 702 to 704. Conversely, in the event of an anomaly such as a short circuit between the vibration zones 22, the voltage output from the second to fourth pad sections 702 to 704 changes. Furthermore, in the event of an anomaly such as a broken wire between the vibration zones 22, no voltage is output from the second to fourth pad sections 702 to 704. Therefore, the control unit 120a compares the voltage of the second to fourth pad sections 702 to 704 with a specified threshold range to determine an anomaly.

[0249] Furthermore, the control unit 120a of this embodiment performs a self-diagnosis to infer the pressure of the rear space S2. Moreover, the control unit 120a corrects the pressure detection signal output from the piezoelectric element 1 based on the inferred pressure.

[0250] That is, in the piezoelectric device described above, the vibration mode of the vibration region 22 changes due to pressure variations in the rear space S2. Specifically, the pressure in the rear space S2 varies depending on the ambient temperature, humidity, and the height used (i.e., the location). Moreover, the vibration region 22 is less likely to vibrate when the pressure in the rear space S2 is higher, and more likely to vibrate when the pressure in the rear space S2 is lower. In other words, in the piezoelectric device described above, there is a possibility that the detection sensitivity will vary due to the operating environment. Therefore, in this embodiment, the pressure in the rear space S2 is inferred, and the pressure detection signal output from the piezoelectric element 1 is corrected based on the inferred pressure.

[0251] Specifically, in order to infer the pressure in the rear space S2, the control unit 120a applies a pressure inference signal to the piezoelectric element 1, thereby causing each vibration region 22 to vibrate inference. In this case, the control unit 120a maximizes the vibration of each vibration region 22 at the resonant frequency by increasing the vibration of each vibration region 22. Furthermore, the control unit 120a performs subsequent operations based on the difference between the voltage of the second to fourth pads 702 to 704 when the pressure inference signal is applied and the voltage of the second to fourth pads 702 to 704 when the anomaly determination signal is applied. That is, the control unit 120a calculates the Q value as the resonance ratio and performs a self-diagnosis to infer the pressure in the rear space S2 based on the Q value.

[0252] Furthermore, the specific calculation method can be appropriately modified when calculating the Q value. For example, the Q value can be calculated based on the difference between the voltage of the second to fourth pads 702 to 704 when the pressure inference signal is applied and the voltage of the second to fourth pads 702 to 704 when the anomaly determination signal is applied. Alternatively, the Q value can be calculated based on the average of the differences between the voltage of the second to fourth pads 702 to 704 when the pressure inference signal is applied and the voltage of the second to fourth pads 702 to 704 when the anomaly determination signal is applied.

[0253] Furthermore, when detecting sound pressure, the control unit 120a corrects the pressure detection signal output from the piezoelectric element 1 based on the inferred pressure of the rear space S2. Specifically, the control unit 120a multiplies the pressure detection signal by a correction coefficient corresponding to the pressure of the rear space S2, based on the assumption that the pressure of the rear space S2 is atmospheric pressure. For example, if the pressure of the rear space S2 is greater than atmospheric pressure, the control unit 120a uses a value greater than 1 as the correction coefficient to multiply the pressure detection signal for correction, since the vibration region 22 is less likely to vibrate. On the other hand, if the pressure of the rear space S2 is less than atmospheric pressure, the control unit 120a uses a value less than 1 as the correction coefficient to multiply the pressure detection signal for correction, since the vibration region 22 is more likely to vibrate. Thus, the pressure detection signal becomes a value corresponding to the pressure of the rear space S2 (i.e., the ease of vibration of the vibration region 22). In addition, the correction coefficient is derived, for example, through prior experiments, and stored in the control unit 120a in correspondence with the pressure of the rear space S2.

[0254] According to the embodiment described above, the detection accuracy can be improved by performing self-diagnosis. Specifically, since the piezoelectric element 1 is malfunctioning, the detection accuracy can be improved by stopping the sound pressure detection when an malfunction occurs. Furthermore, since the pressure in the rear space S2 is inferred, the detection accuracy can be improved by performing correction based on the inferred pressure.

[0255] (A variation of the sixteenth embodiment)

[0256] A variation of the sixteenth embodiment described above will be explained. In the sixteenth embodiment, the control unit 120a can also function as one of the self-diagnostic methods for determining anomalies and inferring the pressure of the rear space S2. Furthermore, in the sixteenth embodiment, when inferring the pressure of the rear space S2, the control unit 120a can also refrain from vibrating each vibration region 22 at its resonant frequency if the vibration is different from normal vibration. However, by maximizing the vibration of each vibration region 22 at its resonant frequency, the difference from normal vibration can be increased, thereby improving the accuracy of the pressure inference of the rear space S2.

[0257] (Seventeenth Implementation)

[0258] The seventeenth embodiment will be described. In this embodiment, compared to the first embodiment, the film thicknesses of the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are specified. Other aspects are the same as in the ninth embodiment, therefore, descriptions are omitted here.

[0259] like Figure 39As shown, the piezoelectric element 1 in this embodiment has the same configuration as in the first embodiment described above. However, in this embodiment, the piezoelectric element 1 does not have a stress-increasing gap 42.

[0260] Furthermore, in this embodiment, the thickness of the lower electrode film 61 and the upper electrode film 63 is thinner than the thickness of the intermediate electrode film 62. For example, in this embodiment, the thickness of the lower electrode film 61 and the upper electrode film 63 is set to 25 nm, and the thickness of the intermediate electrode film 62 is set to 100 nm. In addition, the thickness between the lower electrode film 61 and the intermediate electrode film 62 in the lower piezoelectric film 51, and the thickness between the intermediate electrode film 62 and the upper electrode film 63 in the upper piezoelectric film 52 are the same as in the first embodiment described above, for example, set to 50 μm.

[0261] Furthermore, the lower electrode film 61 and the upper electrode film 63 are set to have the same rigidity. In this embodiment, the lower electrode film 61 and the upper electrode film 63 are made of the same material, and have the same rigidity because of their equal film thickness.

[0262] Furthermore, in this embodiment, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 disposed in the first region R1 and the second region R2 are respectively configured as described above. However, it is sufficient that at least 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 are configured as described above. In addition, in this embodiment, the configuration of the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 corresponds to the raised portion.

[0263] As explained above, in this embodiment, the thickness of the lower electrode film 61 and the upper electrode film 63 are thinner than the thickness of the intermediate electrode film 62, and the rigidity of the lower electrode film 61 and the upper electrode film 63 are set to be equal. Therefore, by improving sensitivity, the detection accuracy can be improved.

[0264] That is, each vibration region 22, as described above, has one end 22a as a fixed end and the other end 22b as a free end. Therefore, as... Figure 40 As shown, for example, in each vibration region 22, when a load (i.e., sound pressure) is applied from the upper electrode film 63 side to the lower electrode film 61 side, compressive stress is applied on the lower piezoelectric film 51 side and tensile stress is applied on the upper piezoelectric film 52 side. Moreover, the center of each vibration region 22 in the thickness direction becomes a neutral surface Cs that is neither subjected to compressive stress nor tensile stress.

[0265] In this case, such as Figure 41 as well as Figure 42As shown, the compressive stress applied to the lower piezoelectric film 51 increases further away from the central plane Cs. Similarly, the tensile stress applied to the upper piezoelectric film 52 increases further away from the central plane Cs. Therefore, by forming the lower piezoelectric film 51 and the upper piezoelectric film 52 to include positions away from the central plane Cs, a configuration that includes areas with higher stress can be achieved. That is, by forming the lower piezoelectric film 51 and the upper piezoelectric film 52 to include positions away from the central plane Cs, a configuration that includes areas where charge is easily generated can be achieved. However, by simply increasing the thickness of the lower piezoelectric film 51 to include positions away from the central plane Cs, the gap between the lower electrode film 61 and the intermediate electrode film 62 widens, thus reducing the capacitance between the lower electrode film 61 and the intermediate electrode film 62. Similarly, by simply increasing the thickness of the upper piezoelectric film 52 to include the position away from the central plane Cs, the spacing between the intermediate electrode film 62 and the upper electrode film 63 becomes wider, thus reducing the capacitance between the intermediate electrode film 62 and the upper electrode film 63.

[0266] Therefore, as in this embodiment, by thickening the intermediate electrode film 62 and thinning the lower electrode film 61, the lower piezoelectric film 51 can include the portion away from the central plane Cs without changing its thickness. Similarly, by thickening the intermediate electrode film 62 and thinning the upper electrode film 63, the upper piezoelectric film 52 can include the portion away from the central plane Cs without changing its thickness. Therefore, the charge generated in the lower piezoelectric film 51 and the upper piezoelectric film 52 can be increased, and the detection accuracy can be improved by increasing sensitivity.

[0267] Furthermore, the lower electrode film 61 and the upper electrode film 63 are made of materials such as molybdenum, copper, platinum, platinum, and titanium, and have a larger Young's modulus compared to materials such as aluminum scandium nitride that constitute the lower piezoelectric film 51 and the upper piezoelectric film 52. Therefore, the thicker the lower electrode film 61 and the upper electrode film 63, the easier it is to hinder the deformation of the lower piezoelectric film 51 and the upper piezoelectric film 52. Therefore, as in this embodiment, by making the thickness of the lower electrode film 61 and the upper electrode film 63 thinner than the thickness of the intermediate electrode film 62, the deformation of the lower piezoelectric film 51 and the upper piezoelectric film 52 can be suppressed compared to the case where the thickness of the lower electrode film 61 and the upper electrode film 63 is the same as the thickness of the intermediate electrode film 62. Therefore, the decrease in sensitivity can be suppressed, and the detection accuracy can be improved.

[0268] Furthermore, the rigidity of the lower electrode film 61 and the upper electrode film 63 is set to be equal. Therefore, when sound pressure is applied, the different deformation modes of the lower piezoelectric film 51 and the upper piezoelectric film 52 can be suppressed, and the overall deformation can be prevented from being hindered.

[0269] (A variation of the seventeenth embodiment)

[0270] A variation of the seventeenth embodiment described above will be explained. In the seventeenth embodiment, the lower electrode film 61 and the upper electrode film 63 can be configured as follows, provided that their film thicknesses are thinner than those of the intermediate electrode film 62 and their rigidity is equal. That is, the lower electrode film 61 and the upper electrode film 63 can be made of different materials and configured to have equal rigidity by adjusting their film thicknesses.

[0271] (Eighteenth Implementation)

[0272] The eighteenth embodiment will be described. In this embodiment, the number of charge regions 620 is defined based on the parasitic capacitance Cp, compared to the eleventh embodiment. Other aspects are the same as in the eleventh embodiment, therefore, descriptions are omitted here.

[0273] The piezoelectric element 1 in this embodiment is the same as that in the eleventh embodiment described above. The first intermediate electrode film 62a is divided into multiple charge regions 620, and each charge region 620 is connected in series. Furthermore, each charge region 620 is provided with the same area and is connected in series with each other.

[0274] Here, when the sensitivity (i.e., output voltage) of the piezoelectric element 1 is set to ΔV, the overall capacitance of the sensing and detection unit 30 is set to Co, the parasitic capacitance is set to Cp, the acoustic-electric conversion coefficient when sound pressure is converted into voltage is set to Γ, and the number of charge regions 620 is set to n, the following equation 3 holds true.

[0275] (Equation 3) ΔV=Γ×{Co / (Co+Cp)}

[0276] Furthermore, the parasitic capacitance Cp is the sum of the capacitance of the portion connecting the piezoelectric element 1 (i.e., the sensing unit 30) and the circuit board 120, or the capacitance generated inside the circuit board 120. Additionally, since the charge regions 620 are connected in series, the capacitance Co of the sensing unit 30 is equal to 1 / n. 2 Proportional.

[0277] Therefore, as Figures 43A to 43C As shown, when the length from one end 22a to the other end 22b in the vibration region 22 is defined as length d, the sensitivity varies depending on the length d, the number of charge regions 620, and the parasitic capacitance Cp. Furthermore, it is currently desirable to improve sensitivity, and practically, this ranges from the maximum sensitivity to approximately 90%. Therefore, in this embodiment, the number of charge regions 620 is set in a manner that results in 90% or more of the maximum sensitivity. For example, as... Figure 43B As shown, the length d from one end 22a to the other end 22b in the vibration region 22 is 490 μm, and the parasitic capacitance Cp is 2.0 × 10⁻⁶. -12In case F, by forming the total number of charge regions 620 to 8 to 16, the sensitivity can be reduced. That is, by setting the number of charge regions 620 in each vibration region 22 to 2 to 4, the sensitivity can be reduced.

[0278] In the embodiment described above, the number of charge regions 620 is specified to be 90% or more of the maximum sensitivity. Therefore, by increasing the sensitivity, the detection accuracy can be improved.

[0279] (Nineteenth Implementation)

[0280] The nineteenth embodiment will be described. In this embodiment, the acoustic compliance Cf of the pressure surface space S1, the acoustic compliance Cb of the rear space S2, and the acoustic resistance Rg of the separation gap 41 are adjusted when the piezoelectric device is configured as in the ninth embodiment. Other aspects are the same as in the ninth embodiment, so the description is omitted here.

[0281] like Figure 44 As shown, the piezoelectric device of this embodiment is configured such that it is mounted on one side 131a of the printed circuit board 131 via the bonding member 2 through the other side 11b of the support substrate 11 in the piezoelectric element 1. Furthermore, in this embodiment, compared with the tenth embodiment described above... Figure 17 Similar to the piezoelectric device described, a through-hole 131b is formed on the printed circuit board 131. Therefore, in this embodiment, sound pressure is detected by applying sound pressure to the sensing unit 30 through the through-hole 131b. Furthermore, in this embodiment, the space between the portion where the through-hole 131b is formed and the sensing unit 30 within the housing 130 is called the pressure-bearing surface space S1. The space located on the opposite side of the pressure-bearing surface space S1, separated by the sensing unit 30, and continuous with this space without being separated by the separation gap 41, is called the rear space S2.

[0282] Furthermore, although a recessed structure is not formed on the support substrate 11 of the piezoelectric element 1 in this embodiment, a recessed structure may still be formed on the support substrate 11. Additionally, the piezoelectric element 1 in this embodiment does not have the stress-increasing gap 42 as described in the first embodiment, but the stress-increasing gap 42 may still be formed. Hereinafter, Figure 44 The following description is based on a piezoelectric device constructed in that manner, but the following configuration can also be applied to a piezoelectric device that uses the piezoelectric element 1 of each of the above embodiments.

[0283] First, the sensitivity of the piezoelectric device depends on the low-frequency roll-off frequency, the resonant frequency of piezoelectric element 1, and the Helmholtz frequency. Specifically, when the low-frequency roll-off frequency is set to fr, it is represented by the following equation 4. When the resonant frequency of piezoelectric element 1 is set to fmb, it is represented by the following equation 5. When the Helmholtz frequency is set to fh, it is represented by the following equation 6.

[0284] [Formula 4]

[0285]

[0286] [Formula 5]

[0287]

[0288] [Formula 6]

[0289]

[0290] Furthermore, Lm in Equation 5 is a constant proportional to the overall mass of each vibration region 22 of the piezoelectric element 1. Lf in Equation 6 is the acoustic mass (inertia) of the through hole 132a.

[0291] Furthermore, the acoustic mass Lf of the through hole 132a is expressed by the following equation 7. Additionally, the acoustic compliance Cf of the pressure surface space S1 is expressed by the following equation 8. The acoustic compliance Cb of the rear space S2 is expressed by the following equation 9. The acoustic resistance Rg of the separation slit 41 is expressed by the following equation 10.

[0292] [Formula 7]

[0293]

[0294] [Formula 8]

[0295]

[0296] [Formula 9]

[0297]

[0298] [Formula 10]

[0299]

[0300] In addition, in equations 7 to 10, ρ0 is the air density, a is the radius of the through hole 132a, and L1 is the thickness of the printed circuit board 131 (i.e., the length of the through hole 132a). Furthermore, Vf is the volume of the pressure-bearing surface space S1, Vb is the volume of the rear space S2, and c is the speed of sound. μ is the frictional resistance of the air, h is the thickness of the vibration region 22, g is the width of the separation gap 41, and L2 is the length of the separation gap 41 in each vibration region 22. The width g of the separation gap 41 refers to the interval between the opposing portions of the sides of each vibration region 22, for example... Figure 36 The width of the portion shown. The length L2 of the separation gap 41 is, for example, [missing information]. Figure 36 The length of the portion shown.

[0301] Moreover, such as Figure 45 As shown, the piezoelectric device in this embodiment is configured such that the frequency increases in the following order: low-frequency roll-off frequency fr, resonant frequency fmb of piezoelectric element 1, and Helmholtz frequency fh. Specifically, each frequency, as shown in equations 4 to 6 above, is based on the acoustic compliance Cf of the pressure surface space S1, the acoustic compliance Cb of the rear space S2, and the acoustic resistance Rg of the separation gap 41. Therefore, the value of each frequency is adjusted by adjusting the acoustic compliance Cf of the pressure surface space S1, the acoustic compliance Cb of the rear space S2, and the acoustic resistance Rg of the separation gap 41.

[0302] More specifically, increasing the acoustic compliance Cb and acoustic impedance Rg results in a smaller low-frequency roll-off frequency fr. Increasing the acoustic compliance Cm and acoustic compliance Cb results in a smaller resonant frequency fmb of the piezoelectric element 1. In this embodiment, the resonant frequency fmb of the piezoelectric element 1 is adjusted by adjusting the acoustic compliance Cb. Increasing the acoustic mass Lf and acoustic compliance Cf results in a smaller Helmholtz frequency fh. In this embodiment, the Helmholtz frequency fh is adjusted by adjusting the acoustic compliance Cf. Therefore, compared to the case where the Helmholtz frequency fh is less than the resonant frequency fmb of the piezoelectric element 1, since the piezoelectric device is typically used to detect the sound pressure at frequencies between the low-frequency roll-off frequency fr and the resonant frequency fmb, the frequency at which sensitivity can be maintained can be increased.

[0303] Furthermore, in this embodiment, the acoustic compliance Cf, acoustic compliance Cb, and acoustic impedance Rg are adjusted such that the low-frequency roll-off frequency is below 20Hz and the Helmholtz frequency is 20kHz. That is, in this embodiment, the low-frequency roll-off frequency fr and the Helmholtz frequency fh are set to values ​​outside the audible range. Therefore, in the piezoelectric device of this embodiment, the frequency at which sensitivity can be maintained within the audible range can be increased. In addition, the resonant frequency fmb of the piezoelectric element 1 is set to, for example, 13kHz.

[0304] Here, to set the low-frequency roll-off frequency to below 20Hz, it is as follows. That is, the acoustic impedance Rg that affects the low-frequency roll-off frequency fr is expressed as in Equation 10 above. Therefore, to set the low-frequency roll-off frequency to below 20Hz, Equation 4 above is set to below 20Hz, and the acoustic impedance Rg satisfies Rg≥1 / (40π×Cb). Therefore, the width g of the separation gap 41 can be formed in a manner that satisfies Equation 11 below.

[0305] [Formula 11]

[0306]

[0307] Furthermore, the relationship between the acoustic impedance Rg required to set the low-frequency roll-off frequency fr to below 20Hz and the acoustic compliance Cb of the rear space S2 is as follows: Figure 46 As shown. In this case, the relationship between the actual thickness h of the vibration region 22 and the length L2 and width g of the separation slit 41 is as follows: Figure 47 As shown. Therefore, as Figure 47 As shown, a width g of 3μm or less for the separation gap 41 can set the low-frequency roll-off frequency to 20Hz or less.

[0308] Furthermore, in the piezoelectric device described above, when sound pressure is introduced into the pressure-bearing surface space S1, the larger the volume of the rear space S2, the easier it is to increase the sensitivity, and the easier it is to increase the signal-to-noise ratio, i.e., the signal-to-noise ratio. In this case, such as Figure 48 As shown, if the ratio of acoustic compliance Cb to acoustic compliance Cf, i.e., Cb / Cf, is 14 or less, then the signal strength ratio (dB) becomes -3dB or less, which is generally considered to be relatively noisy relative to a reference. Furthermore, the reference here is the signal-to-noise ratio (SN ratio) under the condition of maximizing the signal strength. Moreover, -3dB or less relative to the reference is a range of changes that are difficult for human hearing to perceive. Therefore, in this embodiment, Cb / Cf is set to 14 or less. This allows for noise reduction.

[0309] Furthermore, in the piezoelectric device described above, detection is performed by vibrating the vibration region 22. Moreover, in such a piezoelectric device, even when no sound pressure is introduced into the pressure surface space S1, air particles collide with the vibration region 22 from both the pressure surface space S1 side and the rear space S2 side due to Brownian motion. In this case, if the collisions of air particles from the pressure surface space S1 side differ from those from those from the rear space S2 side, the vibration region 22 vibrates unnecessarily and becomes a significant factor in noise.

[0310] Therefore, in order to reduce noise associated with unnecessary vibration, it is preferable to set the volume of the pressure surface space S1 to be equal to the volume of the rear space S2. This allows for the reduction of noise associated with unnecessary vibration.

[0311] As explained above, in this embodiment, the acoustic compliance Cf, acoustic compliance Cb, and acoustic impedance Rg are adjusted in such a manner that the frequencies increase in the order of low-frequency roll-off frequency fr, resonant frequency fmb of piezoelectric element 1, and Helmholtz frequency fh. Therefore, compared to the case where the Helmholtz frequency fh is set to be smaller than the resonant frequency fmb of piezoelectric element 1, the frequency at which sensitivity can be maintained can be increased.

[0312] Furthermore, in this embodiment, the low-frequency roll-off frequency fr is set to 20Hz or less, and the Helmholtz frequency fh is set to 20kHz or more. Therefore, sensitivity within the audible range can be maintained. In this case, by setting the width g of the separation slit 41 to 3μm or less, the low-frequency roll-off frequency fr can be set to 20Hz or less.

[0313] Furthermore, in this embodiment, Cb / Cf is set to 14 or less. Therefore, noise reduction can be achieved.

[0314] Furthermore, in this embodiment, by setting the volume of the pressure surface space S1 to be equal to the volume of the rear space S2, it is possible to reduce noise associated with unnecessary vibrations.

[0315] (Other implementation methods)

[0316] This disclosure is based on embodiments, but it should be understood that this disclosure is not limited to these embodiments or structures. This disclosure also includes various modifications and equivalent variations. In addition, various combinations and methods, including only one element, or other combinations and methods above or below, also fall within the scope and spirit of this application.

[0317] For example, in the above embodiments, the vibration part 20 can be configured to have at least one piezoelectric film 50 and one electrode film 60.

[0318] Furthermore, in the above embodiments, the floating region 21b in the vibration unit 20 may not be divided into four vibration regions 22, but may be divided into three or fewer vibration regions 22, or may be divided into five or more vibration regions 22.

[0319] Furthermore, in the above embodiments, the sensing unit 30 may also be composed of a single vibration region 22. That is, for example, in the first embodiment described above, four sensing units 30 may be constructed using four vibration regions 22, each composed of a single floating region 21b. In this case, in the seventh embodiment described above, the configuration is set to have only one floating region 21b, and multiple vibration regions 22 are formed within that floating region 21b, with each vibration region 22 having a different resonant frequency.

[0320] Furthermore, in the first embodiment described above, instead of forming a stress-increasing gap 42, a separation gap 41 may be formed to reach the corner of the floating region 21b, and the corner C1 is formed by recessing inward through the separation gap 41 in the first region R1.

[0321] Furthermore, in the third embodiment described above, one end 22a of the vibration region 22 may be shaped to have a portion that bulges out relative to the virtual line K1 towards the side opposite to the other end 22b, or it may not be arc-shaped. Similarly, in the fourth embodiment described above, one end 22a of the vibration region 22 may be shaped to have a portion that bulges out relative to the virtual line K2 towards the side opposite to the other end 22b, or it may not be arc-shaped.

[0322] Furthermore, in the fifth embodiment described above, the hard film 82 can be formed equally between the first region R1 side and the other end 22b side in the second region R2, or the first region R1 side can be formed more densely than the other end 22b side. Additionally, in the fifth embodiment described above, the hole 81 embedded in (buried) the hard film 82 can be formed without penetrating the upper electrode film 63, the upper piezoelectric film 52, the intermediate electrode film 62, and the lower piezoelectric film 51. For example, the hole 81 can also be formed only penetrating the upper electrode film 63 and the upper piezoelectric film 52. That is, the depth of the hard film 82 formed in the second region R2 can be appropriately varied. Moreover, in the fifth embodiment described above, the material of the hard film 82 can be different from that of the first and second electrode portions 71 and 72, as long as it is a material with a higher Young's modulus than the piezoelectric film 50, and the material is not particularly limited.

[0323] Furthermore, in the sixth embodiment described above, the stress-increasing gap 42 may not be formed. As such a piezoelectric element 1, it is also possible to suppress the decrease in detection accuracy. Moreover, in the sixth embodiment described above, the temperature sensing element 91 and the heating element 92 can be disposed either in the portion where the lower electrode film 61 is formed or in the portion where the upper electrode film 63 is formed. Furthermore, in the sixth embodiment described above, the temperature sensing element 91 and the heating element 92 may also be formed in the first region R1. Moreover, as described in the seventh embodiment and the like, in the embodiments following the seventh embodiment, the stress-increasing gap 42 is not formed. However, the stress-increasing gap 42 may be appropriately formed in each embodiment. Furthermore, in the sixteenth embodiment described above, the detection accuracy can be improved through the operation of the control unit 120a. Therefore, in the sixteenth embodiment described above, it is also possible not to form an enhancement portion in the piezoelectric element 1.

[0324] Furthermore, in the seventh embodiment described above, the resonant frequencies of the vibration regions 22 in each of the sensing and detection units 30 only need to be different, and the configuration of the vibration regions 22 can be appropriately changed. For example, the resonant frequencies of the vibration regions 22 in each of the sensing and detection units 30 can also be made different by using different film thicknesses and materials.

[0325] Furthermore, when the film thickness and material of each vibration region 22 in each sensing unit 30 are set to be different, for example, the film thickness and material can be made different by appropriately arranging the mask when forming the piezoelectric film 50 constituting the vibration region 22. Additionally, the film thickness can be adjusted by etching or the like after the piezoelectric film 50 is formed, or other piezoelectric films 50 can be formed again in the etched portion, thus making the film thickness and material different. In the case of forming other piezoelectric films 50 again in the etched portion, for example, the side of the etched portion can be made tapered, making it difficult to form gaps between it and the newly formed piezoelectric films 50, which is preferable. Thus, when the film thickness and material are different, the most suitable one can be easily selected according to the application. Furthermore, the length between one end 22a and the other end 22b of each vibration region 22 can also be different, and the film thickness and material can also be changed.

[0326] Furthermore, the above embodiments can be appropriately combined. For example, the first embodiment can be appropriately combined with the above embodiments, forming a corner C1 in the portion of the first region R1 that floats from the support 10. The second embodiment can be appropriately combined with the above embodiments, forming a corner C2 at one end of the first region R1. The third embodiment can be appropriately combined with the above embodiments, making the opening end of the recess 10a round. The fourth embodiment can be appropriately combined with the above embodiments, making the opening end of the recess 10a round, and forming a separation gap 41 in the floating region 21b, which terminates within the floating region 21b. The fifth embodiment can be appropriately combined with the above embodiments, distributing a hard membrane 82 in the second region R2. The sixth embodiment can be appropriately combined with the above embodiments, distributing a temperature detection element 91 and a heating element 92. The seventh embodiment can be appropriately combined with the above embodiments, configured to include multiple sensing units 30. Alternatively, the eighth embodiment described above can be appropriately combined with the other embodiments described above, and a protective film 100 can be provided on the side of the recess 10a. Alternatively, the ninth embodiment described above can be appropriately combined with the other embodiments described above, and a recessed structure can be formed on the side 11c of the support substrate 11. Alternatively, the tenth embodiment described above can be combined with the other embodiments described above, and the piezoelectric element 1 can be flip-chip mounted on the printed circuit board 131. Alternatively, the eleventh embodiment described above can be appropriately combined with the other embodiments described above, and the shape of the intermediate electrode film 62 can be changed. Alternatively, the twelfth and thirteenth embodiments described above can be combined with the other embodiments described above, and the division method of the first region R1 and the second region R2 can be changed. Alternatively, the fourteenth embodiment described above can be combined with the other embodiments described above, and each vibration region 22 can be warped, and each vibration region 22 can be connected in parallel with the circuit board 120. Alternatively, the fifteenth embodiment described above can be combined with the other embodiments described above, and a configuration including a reflective film 140 can be provided. Alternatively, the sixteenth embodiment described above can be combined with the other embodiments described above, and self-diagnosis can be performed when constructing the piezoelectric device. Alternatively, the seventeenth embodiment described above can be combined with other embodiments to make the thickness of the lower electrode film 61 and the upper electrode film 63 thinner than that of the intermediate electrode film 62, and to set the rigidity of the lower electrode film 61 and the upper electrode film 63 to be equal. Alternatively, the eighteenth embodiment described above can be combined with other embodiments to adjust the number of charge regions 620 to 90% or more of the maximum sensitivity. Alternatively, the nineteenth embodiment described above can be combined with other embodiments to adjust the low-frequency roll-off frequency fr, the resonant frequency fmb of the piezoelectric element 1, and the Helmholtz frequency fh to increase sequentially. Furthermore, the configurations formed by combining the above embodiments can be further combined with each other. Additionally, in the above embodiments and the configurations formed by combining the embodiments, it is also possible to set a configuration by removing a portion of the constituent elements as needed.For example, as described above, in the sixth embodiment and the like, the stress-increasing gap 42 may not be formed.

Claims

1. A piezoelectric element having a vibrating portion that outputs a pressure detection signal corresponding to pressure, the piezoelectric element comprising: Support body; and The vibrating unit, disposed on the support body, comprises a piezoelectric film and an electrode film connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film. The vibrating unit has a support region supported on the support body and a floating region connected to the support region and floating from the support body. The vibrating unit outputs a pressure detection signal based on the charge. The floating area is divided by separation gaps and stress-increasing gaps to form multiple vibration zones. The plurality of vibration regions each have one end that serves as the boundary between the vibration region and the support region designated as a fixed end, and the other end designated as a free end. The region on the side of the one end is designated as a first region, and the region on the side of the other end is designated as a second region. The electrode film is formed in the first region. The piezoelectric element includes an enhancement section that improves the detection accuracy of the pressure detection signal. The plurality of vibration regions are formed with deformation-promoting structures that promote deformation of the first region as the lifting portion. The separation slit extends to the end of the floating region on the support region side. The stress-increasing gap is formed to connect with the separation gap in the first region, and a corner is formed at the connection with the separation gap. The deformation-promoting structure is the corner portion formed at the connection between the separation gap and the stress-increasing gap.

2. The piezoelectric element as described in claim 1, The deformation-promoting structure is formed by having a corner at one end of the first region.

3. The piezoelectric element as described in claim 1, The deformation-promoting structure is a corner formed in the first region from the floating portion of the support.

4. The piezoelectric element as described in claim 3, The corner is a curved shape with curvature.

5. The piezoelectric element as described in claim 3, The two ends of the support area side on the outline of the floating area within the vibration zone reach one end. The vibration region, as the deformation-promoting structure, is configured such that one end has a shape that bulges out toward the opposite side of the other end relative to the virtual line connecting the two ends.

6. The piezoelectric element as described in claim 1, The two ends of the support area side of the outline of the floating area within the vibration area terminate at the floating area. For the vibration region, as the deformation-promoting structure, one end has a portion that bulges out toward the opposite side of the other end relative to the virtual line connecting the two ends to each other.

7. The piezoelectric element as described in claim 1, A hole is formed in the second region, and a hard film with a higher Young's modulus than the piezoelectric film is disposed in the hole as the deformation-promoting structure.

8. The piezoelectric element as described in claim 7, The dura mater is formed such that the other end side is denser than the first region side.

9. The piezoelectric element as described in claim 7, The hard membrane is made of the same material as the electrode membrane.

10. The piezoelectric element as claimed in claim 1, A temperature detection element that outputs a temperature detection signal corresponding to the temperature and a heating element that generates heat due to energization are formed in the vibration region, serving as the lifting part.

11. The piezoelectric element as claimed in claim 10, The temperature sensing element and the heating element are formed in the second region.

12. The piezoelectric element as described in claim 10, The piezoelectric film is formed by stacking a lower piezoelectric film and an upper piezoelectric film from the support side. The temperature sensing element and the heating element are disposed between the lower piezoelectric film and the upper piezoelectric film.

13. The piezoelectric element as described in claim 1, The vibration region is formed in multiple ways, and at least a portion of them are formed as the lifting part with different resonant frequencies.

14. The piezoelectric element as described in claim 13, For at least a portion of the vibration region with different resonant frequencies, the length between one end and the other end is different.

15. The piezoelectric element as described in claim 13, For at least a portion of the vibration regions with different resonant frequencies, the thickness of the vibration regions is different.

16. The piezoelectric element as claimed in claim 13, For at least a portion of the vibration regions with different resonant frequencies, the materials constituting the vibration regions are different.

17. The piezoelectric element as claimed in claim 1, The support body has a support base plate and an insulating film disposed on the support base plate and on which the vibration part is disposed. A recess that allows the vibration region to float is formed on the support base plate and the insulating film. When the opening on the opposite side of the insulating film side in the recess formed on the support substrate is designated as the first opening and the opening on the insulating film side is designated as the second opening, the side connecting the first opening and the second opening is configured as the raised portion, and is recessed relative to the virtual line connecting the first opening and the second opening.

18. The piezoelectric element as claimed in claim 17, The supporting substrate is a silicon substrate, and one side of the insulating film is the (110) surface. The side surface of the support substrate is (111).

19. The piezoelectric element as claimed in claim 1, The electrode film and the piezoelectric film are arranged in a manner in which the lower electrode film, the lower piezoelectric film, the intermediate electrode film, the upper piezoelectric film, and the upper electrode film are stacked sequentially from the support body side. The intermediate electrode film, serving as the lifting section, is divided into multiple charge regions of equal area, and these charge regions are connected in series. The vibration unit outputs the pressure detection signal, which is based on the charge generated between the charge regions of the lower electrode film and the intermediate electrode film, and the charge generated between the charge regions of the upper electrode film and the intermediate electrode film.

20. The piezoelectric element as claimed in claim 19, The plurality of charge regions are set to be more than 90% of the maximum detection sensitivity of the piezoelectric element.

21. The piezoelectric element as claimed in claim 1, When the vibration region is divided into multiple virtual regions along a direction intersecting the first end, and the capacitance of each virtual region is set as C, and the average stress generated by the virtual region is set as σ, the first and second regions among the multiple vibration regions serve as the lifting section, by multiplying C × σ in each of the virtual regions. 2 It is divided by becoming the boundary line connecting the largest regions.

22. The piezoelectric element as claimed in claim 1, When the vibration region is divided into multiple virtual regions along a direction intersecting the first end, and the area of ​​each virtual region is set as S, and the sum of the stresses generated by the virtual regions is set as σsum, the first and second regions of the multiple vibration regions serve as the lifting part, by adjusting the (σsum) in each of the virtual regions. 2 / S becomes the boundary line of the largest region connection and is thus divided.

23. The piezoelectric element as claimed in claim 1, The multiple vibration regions are planar triangular in shape. The first and second regions of the plurality of vibration regions, as the lifting portion, are divided into three triangles by dividing the vibration region into three equal parts at one end. The first and second regions of the plurality of vibration regions are divided by the boundary line connecting the centroid of the three triangles to the two ends of the one end.

24. The piezoelectric element as claimed in claim 1, The plurality of vibration regions, serving as the lifting portion, have one end warped relative to the first end. The vibration unit, serving as the lifting unit, outputs the pressure detection signal from each of the plurality of vibration regions.

25. The piezoelectric element as described in any one of claims 1 to 24, The electrode film and the piezoelectric film are arranged in a manner in which the lower electrode film, the lower piezoelectric film, the intermediate electrode film, the upper piezoelectric film, and the upper electrode film are stacked sequentially from the support body side. For the lower electrode film, the intermediate electrode film, and the upper electrode film, as the lifting portion, the thickness of the lower electrode film and the upper electrode film is thinner than the thickness of the intermediate electrode film, and the rigidity of the lower electrode film and the upper electrode film are equal.

26. A piezoelectric element having a vibrating portion that outputs a pressure detection signal corresponding to pressure, the piezoelectric element comprising: Support body; and The vibrating unit, disposed on the support body, comprises a piezoelectric film and an electrode film connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film. The vibrating unit has a support region supported on the support body and multiple vibration regions connected to the support region and floating from the support body. The vibrating unit outputs a pressure detection signal based on the charge. The plurality of vibration regions each have one end that serves as the boundary between the vibration region and the support region designated as a fixed end, and the other end designated as a free end. The region on the side of the one end is designated as a first region, and the region on the side of the other end is designated as a second region. The electrode film is formed in the first region. The piezoelectric element includes an enhancement section that improves the detection accuracy of the pressure detection signal. The plurality of vibration regions, serving as the lifting portion, have a reflective film with a higher reflectivity than the piezoelectric film disposed in the second region.

27. The piezoelectric element as claimed in claim 26, The reflective film is made of a material with a lower Young's modulus compared to the piezoelectric film.

28. The piezoelectric element as described in claim 26 or 27, The electrode film and the piezoelectric film are arranged in a manner in which the lower electrode film, the lower piezoelectric film, the intermediate electrode film, the upper piezoelectric film, and the upper electrode film are stacked sequentially from the support body side. For the lower electrode film, the intermediate electrode film, and the upper electrode film, as the lifting portion, the thickness of the lower electrode film and the upper electrode film is thinner than the thickness of the intermediate electrode film, and the rigidity of the lower electrode film and the upper electrode film are equal.

29. A piezoelectric element having a vibrating portion that outputs a pressure detection signal corresponding to pressure, the piezoelectric element comprising: Support body; and The vibrating unit, disposed on the support body, has a piezoelectric film and an electrode film connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film. The vibrating unit has a support region supported on the support body and multiple vibration regions connected to the support region and floating from the support body. The vibrating unit outputs a pressure detection signal based on the charge. Each of the plurality of vibration regions has one end, which serves as the boundary between the vibration region and the support region, designated as a fixed end, and the other end as a free end. The region on the side of the one-end is designated as a first region, and the region on the side of the free end is designated as a second region. Furthermore, the resonant frequencies of the vibration regions, which constitute at least a portion of the plurality of vibration regions, are different from each other. The electrode film is disposed in the first region. A temperature detection element that outputs a temperature detection signal corresponding to the temperature, and a heating element that generates heat due to energization, are formed in the vibration region. The piezoelectric film is formed by stacking a lower piezoelectric film and an upper piezoelectric film from the support side. The temperature sensing element and the heating element are disposed between the lower piezoelectric film and the upper piezoelectric film.

30. The piezoelectric element as claimed in claim 29, For at least a portion of the vibration region with different resonant frequencies, the length between one end and the other end is different.

31. The piezoelectric element as described in claim 29, For at least a portion of the vibration regions with different resonant frequencies, the thickness of the vibration regions is different.

32. The piezoelectric element as described in claim 29, For at least a portion of the vibration regions with different resonant frequencies, the materials constituting the vibration regions are different.

33. The piezoelectric element as described in claim 29, The temperature sensing element and the heating element are formed in the second region.

34. A piezoelectric device comprising a piezoelectric element having a vibrating portion that outputs a pressure detection signal corresponding to pressure, the piezoelectric device comprising: The piezoelectric element as described in any one of claims 1 to 33; and The housing has a mounting component on which the piezoelectric element is mounted, and a cover fixed to the mounting component in a state of accommodating the piezoelectric element. The housing has a through hole that communicates with the outside to introduce the pressure.

35. The piezoelectric device as claimed in claim 34, It includes a circuit board mounted on the component being installed. The piezoelectric element has a connection pad portion formed on the piezoelectric film that is electrically connected to the electrode film. The piezoelectric element is flip-chip mounted on the mounted component. The connection pad portion is electrically connected to the circuit board via a wiring portion formed on the mounted component. The connecting pad is disposed on the circuit board side.

36. The piezoelectric device as claimed in claim 35, The piezoelectric element has a dummy pad portion that is in a floating state on the piezoelectric film. The connecting pad portion and the dummy pad portion are symmetrically arranged with reference to the center of the surface of the piezoelectric element that is parallel to the surface direction of the mounted component.

37. The piezoelectric device as claimed in claim 34, When the space within the housing that is different from the pressure-bearing surface space between the through hole and the vibrating part is designated as the rear space, and the acoustic compliance of the piezoelectric element is designated as Cm, and the acoustic compliance of the rear space is designated as Cb, then Cb / Cm is less than 2.

38. The piezoelectric device as claimed in claim 34, The vibrating part has separation gaps that divide the plurality of vibration zones. When the space between the through hole and the vibrating part within the housing is designated as the pressure-bearing surface space, and a space different from the pressure-bearing surface space is designated as the rear space, the acoustic compliance of the piezoelectric element, the acoustic compliance of the pressure-bearing surface space, the acoustic compliance of the rear space, and the acoustic resistance of the separation gap are adjusted such that the frequencies increase in the order of low-frequency roll-off frequency, the resonant frequency of the piezoelectric element, and the Helmholtz frequency.

39. The piezoelectric device as claimed in claim 38, The low-frequency roll-off frequency is below 20Hz. The Helmholtz frequency is above 20kHz.

40. The piezoelectric device as claimed in claim 39, The width of the separation slit is less than 3 μm.

41. The piezoelectric device as claimed in claim 34, When the space within the outer casing that is different from the pressure surface space located between the through hole and the vibrating part is designated as the rear space, and the acoustic compliance of the pressure surface space is designated as Cf, and the acoustic compliance of the rear space is designated as Cb, then Cb / Cf is 14 or less.

42. The piezoelectric device as claimed in claim 34, When the space between the through hole and the vibrating part within the outer shell is designated as the pressure-bearing surface space, and a space different from the pressure-bearing surface space is designated as the rear space, the volume of the pressure-bearing surface space is equal to the volume of the rear space.

43. The piezoelectric device as described in any one of claims 34 to 42, It has a control unit that performs prescribed processing. For the piezoelectric element, the plurality of vibration regions are connected in parallel with the control unit, and the plurality of vibration regions are also connected in series. The control unit applies a specified voltage to cause the multiple vibration regions to vibrate, thereby performing self-diagnosis of the piezoelectric element.

44. The piezoelectric device as claimed in claim 43, The control unit, as the self-diagnostic unit, causes the plurality of vibration regions to vibrate in a manner based on the normal vibration that can be applied to the piezoelectric element, and determines the abnormality of the piezoelectric element based on the voltage between the series-connected vibration regions.

45. The piezoelectric device as claimed in claim 43, The space within the outer casing that is different from the space between the through hole and the vibrating part is designated as the rear space. The control unit, as part of the self-diagnosis, calculates the difference between two voltages to derive the resonance ratio, and infers the pressure in the rear space based on the resonance ratio. The two voltages are: the voltage between the multiple vibration regions when they vibrate in a manner consistent with normal vibration based on pressure that can be applied to the piezoelectric element; and the voltage between the multiple vibration regions when they vibrate in a manner consistent with inferred vibration different from normal vibration. The control unit corrects the pressure detection signal based on the inferred pressure in the rear space.

46. ​​The piezoelectric device as claimed in claim 45, The control unit, as the inferred vibration, causes the plurality of vibration regions to vibrate at a resonant frequency.

47. A method for manufacturing a piezoelectric element, the piezoelectric element comprising: Support body; and A vibration unit, disposed on the support body, comprises a piezoelectric film and an electrode film connected to the piezoelectric film to extract the charge generated by the deformation of the piezoelectric film. The vibration unit has a support region supported on the support body and multiple vibration regions connected to the support region and floating from the support body. The vibration unit outputs a pressure detection signal based on the charge. The plurality of vibration regions each have one end that serves as the boundary between the vibration region and the support region designated as a fixed end, and the other end designated as a free end. The region on the side of the one end is designated as a first region, and the region on the side of the other end is designated as a second region. The electrode film is formed in the first region. The piezoelectric element has an enhancement section that improves the detection accuracy of the pressure detection signal. The manufacturing method of the piezoelectric element is as follows: Prepare the support body; and The vibrating part is formed on the support body. In forming the vibrating section, a recess is formed in the support body to allow the vibrating region to float. The lifting portion is disposed at one end of the first region. In forming the vibrating section, a reflective film with a higher reflectivity than the piezoelectric film is disposed in the second region. After the vibrating part is formed, the warping of the vibrating region is determined based on the intensity of the laser beam reflected when the laser beam is irradiated onto the reflective film.

48. The method for manufacturing a piezoelectric element as described in claim 47, In preparing the support, a support body is prepared having a support substrate made of a silicon substrate and an insulating film disposed on the support substrate. In forming the recess, the following steps are performed: anisotropic dry etching is performed to penetrate the support substrate and the insulating film to make the vibration region float; anisotropic wet etching is performed to form a configuration in which, when the opening on the opposite side of the insulating film side in the recess formed on the support substrate is set as the first opening and the opening on the insulating film side is set as the second opening, the side connecting the first opening and the second opening is recessed relative to the virtual line connecting the first opening and the second opening.

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