Piezoelectric element, microphone

Abstract

To provide a piezoelectric element and a microphone capable of improving detection sensitivity. [Solution] The piezoelectric element comprises a support 10 and a vibrating portion 20 laminated on the support along the lamination direction. The vibrating portion includes a piezoelectric film 40 disposed on the support, an electrode film 50 disposed on the piezoelectric film, and an interlayer insulating film 60 disposed on the piezoelectric film, and has a support region 21 supported by the support and a floating region 22 connected to the support region and floating away from the support. The floating region has a support end 221 which forms the boundary with the support region as a fixed end, and a vibrating end 222 on the opposite side of the support end as a free end. The support has a support substrate 11 and an insulating film 12 disposed on the support substrate on which the vibrating portion is disposed, and floating openings 100 that allow the floating region to float are formed in the support substrate and the insulating film. At least a portion of the end of the interlayer insulating film in the direction of vibration is positioned on the side of the end of the insulating film in the direction of vibration.

Description

Technical Field

[0005] ,

[0001] The present disclosure relates to piezoelectric elements and microphones.

Background Art

[0002] Conventionally, a piezoelectric type MEMS (Micro Electro Mechanical Systems) microphone having a piezoelectric element in which a support and a vibrating portion are laminated in a predetermined lamination direction is known (see, for example, Patent Document 1). The piezoelectric element employed in this MEMS microphone is such that the support is composed of a substrate and an insulating film disposed on the substrate, and the vibrating portion is composed of a piezoelectric film and an electrode. Then, by etching the support, an opening is formed in the support. As a result, in the vibrating portion, a vibrating region having a cantilever support configuration is formed in which one side supported by the insulating film is a fixed end and the other side is a free end.

[0003] When pressure such as sound pressure is applied to the piezoelectric element formed in this manner, the vibrating region supported by the insulating film vibrates with the fixed end side as a fulcrum. Here, the vibrating portion is supported by the insulating film in which an opening is formed. Therefore, the vibrating region vibrates with the inner edge portion of the insulating film, which is the opening end of the opening, as a fulcrum. The MEMS microphone detects the sound pressure by taking out the stress generated in the piezoelectric film due to the vibration of the vibrating region as electric charges via the electrode film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in the piezoelectric element described in Patent Document 1, the opening end of the aperture, that is, the inner edge of the insulating film, overlaps with the piezoelectric film and the electrode film in the stacking direction. Therefore, the stress generated in the piezoelectric film when the vibration region vibrates is concentrated in the area where the piezoelectric film and the electrode film overlap in the vibrating region. As a result, the piezoelectric element is able to extract the charge from the stress-concentrated area in the piezoelectric film via the electrode film.

[0006] Incidentally, when etching is performed to form an opening in the support, the position of the inner edge of the insulating film may deviate from the design position due to manufacturing errors or other factors. If the position of the inner edge of the insulating film shifts to the opposite side of the free end, the position of the pivot point in the vibration region will also shift from the design position to the opposite side of the free end.

[0007] If the pivot point of the vibration region is shifted to a position that does not overlap with the electrode film in the stacking direction, the vibration region will be supported only by the piezoelectric film, with the electrode film not being supported by the insulating film. In this case, the stress generated in the piezoelectric film when the vibration region vibrates will be concentrated in the area where the electrode film is not formed. Consequently, when the piezoelectric element extracts charge from the piezoelectric film via the electrode film, it will extract charge from a position shifted from the stress-concentrated area in the piezoelectric film. However, extracting charge from a position shifted from the stress-concentrated area reduces the voltage detected from the electrode film when the piezoelectric film vibrates, which reduces the detection sensitivity of the piezoelectric element when detecting sound waves.

[0008] In view of the above points, this disclosure aims to provide a piezoelectric element and a microphone capable of improving detection sensitivity. [Means for solving the problem]

[0009] According to one perspective of this disclosure, Piezoelectric elements are Support (10) and It comprises a vibrating part (20) which is stacked on a support along a predetermined stacking direction and vibrates when pressure is applied from the outside, The vibrating part includes a piezoelectric film (40) disposed on a support, an electrode film (50) disposed on the piezoelectric film, and an interlayer insulating film (60) disposed on the piezoelectric film, and also has a support region (21) supported by the support, and a floating region (22) connected to the support region and floating away from the support. In the floating region, the support end (221) that forms the boundary with the support region is considered a fixed end, and the vibrating end (222) on the opposite side of the support end is considered a free end. The support comprises a support substrate (11) and an insulating film (12) disposed on the support substrate and on which the vibrating part is placed, and floating openings (100) are formed in the support substrate and the insulating film to allow the floating region to float. When the direction from the support end to the vibrating end is defined as the vibration end direction, at least a portion of the end of the interlayer insulating film in the vibration end direction is located on the vibration end direction side of the end of the insulating film in the vibration end direction.

[0010] According to this, the pivot point when the vibrating part vibrates is the part that overlaps with the inner edge of the interlayer insulating film in the electrode film in the stacking direction. Therefore, even if the position of the inner edge of the insulating film shifts to the opposite side of the vibration end direction due to manufacturing errors, etc., and the inner edge of the insulating film shifts to a position where it does not overlap with the electrode film in the stacking direction, the position of the pivot point when the vibrating part vibrates does not shift. Consequently, it is possible to avoid the shift in the area where stress concentrates due to the position of the inner edge of the insulating film shifting from the design position, and it is possible to suppress a decrease in the voltage detected from the electrode film. Therefore, the detection sensitivity of the piezoelectric element can be improved.

[0011] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0012] [Figure 1] This is a top view of a piezoelectric element according to the first embodiment. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3]It is a cross-sectional view showing the manufacturing process of the piezoelectric element according to the first embodiment. [Figure 4] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 3. [Figure 5] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4. [Figure 6] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 5. [Figure 7] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 6. [Figure 8] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 7. [Figure 9] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 8. [Figure 10] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 9. [Figure 11] It is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 10. [Figure 12] It is a figure corresponding to FIG. 2 of the piezoelectric element of the comparative example. [Figure 13] It is a contour diagram showing the simulation result of the stress generated in the piezoelectric element of the comparative example. [Figure 14] It is a contour diagram showing the simulation result of the stress when the position of the insulating hole forming portion is shifted toward the support end side in the piezoelectric element of the comparative example. [Figure 15] It is a top view of the piezoelectric element according to the modification of the first embodiment. [Figure 16] It is a top view of the piezoelectric element according to the modification of the first embodiment. [Figure 17] It is a top view of the piezoelectric element according to the second embodiment. [Figure 18] It is a top view of the piezoelectric element according to the modification of the second embodiment. [Figure 19] It is a figure corresponding to FIG. 2 of the piezoelectric element according to the third embodiment. [Figure 20] It is a figure corresponding to FIG. 2 of the piezoelectric element according to the fourth embodiment. [Figure 21] It is a figure corresponding to FIG. 2 of the piezoelectric element according to the fifth embodiment. [Figure 22] This figure corresponds to Figure 2 of a piezoelectric element according to another embodiment. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the prior embodiments will be denoted by the same reference numerals, and their descriptions may be omitted. Also, if only a part of a component is described in an embodiment, the components described in the prior embodiments can be applied to the other parts of that component. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not impede the combination.

[0014] (First Embodiment) The piezoelectric element 1 of the first embodiment will be described with reference to Figures 1 to 14. The piezoelectric element 1 of this embodiment is preferably used as a microphone, for example. As shown in Figures 1 and 2, the piezoelectric element 1 of this embodiment comprises a support 10, a vibrating part 20 stacked on the support 10, and a connecting part 30 connected to the vibrating part 20. Hereinafter, as shown in Figure 2 and other figures, the direction in which the support 10 and the vibrating part 20 are stacked will also be referred to as the stacking direction D1. As shown in Figure 1, the piezoelectric element 1 of this embodiment is formed in a rectangular shape when viewed along the stacking direction D1.

[0015] The support 10 has a rectangular shape when viewed in the direction along the stacking direction D1. The support 10 has a support substrate 11 that supports the vibrating part 20 and an insulating film 12 formed on the support substrate 11. The support 10 has a floating opening 100 formed therein to allow the inner edge side of the vibrating part 20 to float.

[0016] The support substrate 11 is made of, for example, a silicon substrate, and the insulating film 12 is made of, for example, an oxide film. Furthermore, both the support substrate 11 and the insulating film 12 are formed in a rectangular shape when viewed along the stacking direction D1, and are tubular in shape with a through hole in the center. The outer shells of the support substrate 11 and the insulating film 12 are of equal size.

[0017] The support substrate 11 has a substrate through-hole 110 formed through the stacking direction D1, and a substrate hole forming portion 111 surrounding the substrate through-hole 110. The substrate hole forming portion 111 is the inner edge of the support substrate 11 in which the substrate through-hole 110 is formed. The insulating film 12 has an insulating through-hole 120 formed through the stacking direction D1, and an insulating hole forming portion 121 surrounding the insulating through-hole 120. The insulating hole forming portion 121 is the inner edge of the insulating film 12 in which the insulating through-hole 120 is formed.

[0018] Furthermore, the substrate through-holes 110 and insulation through-holes 120 are formed in a rectangular shape when viewed in the direction along the stacking direction D1. Also, the size of the holes in the substrate through-holes 110 is larger than the size of the holes in the insulation through-holes 120, and the insulation hole forming portion 121 is located on the outer edge side of the substrate hole forming portion 111. In other words, the cross-sectional area of ​​the substrate through-holes 110 perpendicular to the stacking direction D1 is larger than the cross-sectional area of ​​the insulation through-holes 120 perpendicular to the stacking direction D1.

[0019] Furthermore, the floating opening 100 of the support 10 is formed by substrate through-holes 110 and insulating through-holes 120 that are connected in the stacking direction D1. In other words, the floating opening 100 for floating the inner edge side of the vibrating part 20 is formed by penetrating the support substrate 11 and insulating film 12 in the stacking direction D1. The substrate through-holes 110 and insulating through-holes 120 are formed in the center of the piezoelectric element 1. Therefore, the floating opening 100 is formed in the center of the piezoelectric element 1.

[0020] The vibrating section 20 constitutes a sensing section that vibrates in response to external pressure and is stacked on the support 10. The vibrating section 20 is positioned on the support 10 and has a support region 21 supported by the support 10, and a floating region 22 that is connected to the support region 21 and floats away from the support 10 above the floating opening 100. The entire floating region 22 has a shape corresponding to the floating opening 100, and specifically, it is approximately rectangular in plan. That is, the floating region 22 is formed in a rectangular shape when viewed in the direction along the stacking direction D1, and its size is equal to the size of the insulating through-hole 120 formed in the insulating film 12 on which the vibrating section 20 is positioned.

[0021] As shown in Figure 1, a separation slit 23 is formed in the floating region 22, penetrating the floating region 22 in the stacking direction D1. In this embodiment, the separation slit 23 is formed to divide the floating region 22 into four sections. More specifically, two separation slits 23 are formed, passing through the center C of the floating region 22 and extending toward the opposing corners of the floating region 22. In other words, the separation slits 23 extend from each corner of the floating region 22, which is roughly rectangular in plan, toward the center C, and are formed so that the two separation slits 23 intersect at the center C.

[0022] As a result, the floating region 22 is separated into four divided floating regions 223 which are roughly triangular in shape. Specifically, the floating region 22 is composed of four divided floating regions 223 which are roughly isosceles triangular in shape, each having two sides of equal length extending toward the center C of the floating region 22 and a base connected to those two sides.

[0023] Although not particularly limited, in this embodiment the width of the separation slit 23 is approximately 1 μm. Furthermore, the width of the separation slit 23 in the direction perpendicular to the direction of extension is constant from one end to the other. In addition, although the separation slit 23 in this embodiment is formed to terminate within the floating region 22, it may extend to the support region 21.

[0024] Each divided floating region 223, which is roughly triangular in shape, is formed by dividing the floating region 22 as described above, so that the base side of the triangle is a fixed end supported by the insulating hole forming portion 121 of the support 10. Each divided floating region 223 is a cantilever with the vertex side opposite the base side being a free end. In other words, each divided floating region 223 is connected to the support region 21 and is also cantilevered.

[0025] Hereinafter, the boundary between each of the four divided floating regions 223 and the support region 21 will be referred to as the support end 221, and the end opposite to the support end 221, i.e., the end on the central C side, will sometimes be referred to as the vibration end 222. The direction from the support end 221 toward the vibration end 222 will be referred to as the vibration end direction D2a, and the direction opposite to the vibration end direction D2a, from the vibration end 222 toward the support end 221, will also be referred to as the support end direction D2b. In this embodiment, the divided floating regions 223 have a cantilevered shape with the support end 221 as the fixed end and the vibration end 222 as the free end. However, as will be described later, each divided floating region 223 is less susceptible to vibration with the portion supported by the insulating hole forming portion 121, which is the inner edge of the insulating film 12, as the fulcrum, by the interlayer insulating film 60.

[0026] The vibrating section 20 has a configuration that includes a piezoelectric film 40, an electrode film 50 connected to the piezoelectric film 40, and an interlayer insulating film 60 arranged across the piezoelectric film 40 and the electrode film 50. Specifically, the piezoelectric film 40 has a lower piezoelectric film 41 and an upper piezoelectric film 42 laminated on the lower piezoelectric film 41. The electrode film 50 has a lower electrode film 51 located below the lower piezoelectric film 41, an intermediate electrode film 52 located between the lower piezoelectric film 41 and the upper piezoelectric film 42, and an upper electrode film 53 located on the upper piezoelectric film 42. In other words, the vibrating section 20 has a bimorph structure in which the lower piezoelectric film 41 is sandwiched between the lower electrode film 51 and the intermediate electrode film 52, and the upper piezoelectric film 42 is sandwiched between the intermediate electrode film 52 and the upper electrode film 53. The lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 are laminated via the lower piezoelectric film 41 and the upper piezoelectric film 42.

[0027] Furthermore, the vibrating section 20 of this embodiment has a base film 70 on which the lower piezoelectric film 41 and the lower electrode film 51 are arranged. In other words, the piezoelectric film 40 and the electrode film 50 are arranged on the support 10 via the base film 70. The base film 70 is not strictly necessary, but is provided to facilitate crystal growth when forming the lower piezoelectric film 41, etc. The base film 70 is made of AlN or the like.

[0028] The lower piezoelectric film 41 and the upper piezoelectric film 42 are made of lead-free piezoelectric ceramics such as scandium aluminum nitride (ScAlN) or aluminum nitride (AlN). Alternatively, the lower piezoelectric film 41 and the upper piezoelectric film 42 may be made of lead zirconate titanate (PZT) or the like.

[0029] The lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 are composed of molybdenum (Mo). However, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 may also be composed of a metallic material whose main component is one of the following: titanium (Ti), platinum (Pt), aluminum (Al), ruthenium (Ru), etc. In addition, the piezoelectric film 40 has a thickness of about 1 μm, and the base film 70 has a thickness of about several tens of nanometers. In other words, the base film 70 is extremely thin compared to the piezoelectric film 40.

[0030] Furthermore, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 are formed in each of the four divided floating regions 223 and are electrically connected in series by the connection part 30. Specifically, each lower electrode film 51, each middle electrode film 52, and each upper electrode film 53 formed in each of the four divided floating regions 223 are connected in parallel, while the divided floating regions 223 are connected in series.

[0031] Furthermore, each of the lower electrode films 51, middle electrode films 52, and upper electrode films 53 formed in each of the four divided floating regions 223 are formed in a shape corresponding to the divided floating region 223, which is approximately triangular in plan. That is, the lower electrode films 51, middle electrode films 52, and upper electrode films 53 are formed in an approximately triangular shape in plan. The triangular cross-sectional area of ​​the lower electrode films 51, middle electrode films 52, and upper electrode films 53 perpendicular to the stacking direction D1 is smaller than the triangular cross-sectional area of ​​the divided floating region 223 perpendicular to the stacking direction D1. In addition, at least a portion of the lower electrode films 51, middle electrode films 52, and upper electrode films 53 overlap each other in the stacking direction D1. In this embodiment, the lower electrode films 51, middle electrode films 52, and upper electrode films 53 completely overlap each other in the stacking direction D1, and their outer edges are formed in approximately the same shape.

[0032] Furthermore, at least one of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 has an end on the support end 221 side of the vibrating part 20 that overlaps with the insulating film 12 in the stacking direction D1. That is, the electrode film 50, including the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53, has an end in the support end direction D2b that overlaps with the insulating film 12 in the stacking direction D1. In this embodiment, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 each have an end on the support end direction D2b that overlaps with the insulating film 12 in the stacking direction D1.

[0033] Furthermore, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 have ends on the support end 221 side of the vibrating section 20 that overlap with the support substrate 11 in the stacking direction D1. That is, the electrode film 50, including the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53, has an end in the support end direction D2b that overlaps with the support substrate 11 in the stacking direction D1. In this embodiment, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 each have ends on the support end direction D2b side that overlap with the support substrate 11 in the stacking direction D1.

[0034] The connection section 30 includes a first electrode section 31 connected to the lower electrode film 51 and the upper electrode film 53, a second electrode section 32 connected to the middle electrode film 52, and a wiring film 33 connecting the first electrode section 31 and the second electrode section 32. The first electrode section 31 and the second electrode section 32 are constructed using materials such as molybdenum, copper, platinum, titanium, and aluminum, similar to the electrode film 50.

[0035] The first electrode portion 31 is positioned in a first electrode hole 311 formed by penetrating the interlayer insulating film 60, the upper electrode film 53, the upper piezoelectric film 42, and the lower piezoelectric film 41. The first electrode portion 31 electrically connects the upper electrode film 53 and the lower electrode film 51. The second electrode portion 32 is positioned in a second electrode hole 321 formed by penetrating the interlayer insulating film 60 and the upper piezoelectric film 42. The second electrode portion 32 is electrically connected to the middle electrode film 52. One first electrode portion 31 and one second electrode portion 32 are formed in each of the four divided floating regions 223. As will be described later, the interlayer insulating film 60 is formed on the wall surface of the first electrode hole 311, the wall surface of the second electrode hole 321, and the upper surface of the upper piezoelectric film 42. As a result, the first electrode portion 31 and the second electrode portion 32 are insulated from the piezoelectric film 40 by the interlayer insulating film 60.

[0036] The wiring film 33 is positioned on the upper surface of the interlayer insulating film 60 and is electrically connected to the first electrode portion 31 and the second electrode portion 32 across four divided floating regions 223. The wiring film 33 electrically connects the four divided floating regions 223 in series. In Figure 1, only the portion of the wiring film 33 that connects the first electrode portion 31 and the second electrode portion 32, and the pad portion that connects to the external circuit are shown.

[0037] The interlayer insulating film 60 is intended to suppress leakage between electrodes. The interlayer insulating film 60, like the insulating film 12, is composed of an oxide film or the like. The size of the outer shell of the interlayer insulating film 60 is smaller than the size of the outer shells of the support substrate 11, insulating film 12, piezoelectric film 40, and electrode film 50. The interlayer insulating film 60 is formed on the upper piezoelectric film 42 and the upper electrode film 53. Specifically, the interlayer insulating film 60 is arranged to span from the upper piezoelectric film 42 to the upper electrode film 53. However, the interlayer insulating film 60 has an interlayer opening 610 in the center that exposes the upper electrode film 53. As a result, a part of the floating region 22 of the upper electrode film 53 is exposed. The interlayer insulating film 60 has an interlayer opening forming portion 611 around the interlayer opening 610 that forms the interlayer opening 610. The interlayer opening forming portion 611 is the inner edge of the interlayer insulating film 60 where the interlayer opening 610 is formed. The interlayer opening forming portion 611 is formed in the center of the piezoelectric element 1, penetrating the interlayer insulating film 60 in the stacking direction D1.

[0038] The interlayer opening 610 is formed in a rectangular shape when viewed in the direction along the lamination direction D1. Furthermore, the size of the opening portion of the interlayer opening 610 is smaller than the size of the substrate through-hole 110 and the insulation through-hole 120, and the interlayer opening forming portion 611 is located on the vibration end direction D2a side of the insulation hole forming portion 121 and the substrate hole forming portion 111. In other words, the cross-sectional area of ​​the interlayer opening 610 perpendicular to the lamination direction D1 is smaller than the cross-sectional area of ​​the substrate through-hole 110 and the insulation through-hole 120 perpendicular to the lamination direction D1. Note that the interlayer insulating film 60 may be made of a different material from the insulating film 12, and may be made of a photosensitive resin such as polyimide.

[0039] As shown in Figures 1 and 2, the interlayer insulating film 60 formed in this manner has an interlayer opening forming portion 611, which is the inner edge of the interlayer insulating film 60, positioned on the free end side of the insulating hole forming portion 121, which is the inner edge of the insulating film 12. In other words, the end of the interlayer insulating film 60 in the vibration end direction D2a is positioned on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a. Therefore, the end of the interlayer insulating film 60 in the vibration end direction D2a and the insulating film 12 do not overlap in the lamination direction D1. In this embodiment, the interlayer insulating film 60 in which the interlayer opening 610 is formed in a rectangular shape has its entire end in the vibration end direction D2a positioned on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a, which has a rectangular insulating through-hole 120. The reason why the end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a will be explained later.

[0040] Furthermore, the end of the interlayer insulating film 60 in the vibration end direction D2a is positioned on the D2a side of the vibration end direction D2a compared to the end of at least one of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 in the support end direction D2b. In other words, the interlayer insulating film 60 has an interlayer opening forming portion 611, which is the inner edge of the interlayer insulating film 60, overlapping with at least one of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 in the stacking direction D1. In this embodiment, the end of the interlayer insulating film 60 in the vibration end direction D2a is positioned on the D2a side of the vibration end direction D2a compared to the end of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 on the support end direction D2b, in the stacking direction D1.

[0041] Here, the vibration portion 20 on which the interlayer insulating film 60 is formed is restricted from vibration by the fact that the portion of the floating region 22 on the side of the interlayer opening forming portion 611 toward the support end D2b is supported by the interlayer opening forming portion 611. In other words, the portion of the floating region 22 from the interlayer opening forming portion 611 toward the support end D2b to the support end 221 is less susceptible to deformation by the interlayer opening forming portion 611.

[0042] Therefore, in this embodiment, a vibration region 224 is formed on the vibration end direction D2a side from the interlayer opening forming portion 611 in the floating region 22. The vibration region 224 is the part that vibrates due to pressure applied from the outside. The vibration region 224 is formed on the vibration end direction D2a side from the interlayer opening forming portion 611 of each of the four divided floating regions 223. Therefore, the vibrating portion 20 has four vibration regions 224 in the floating region 22. The interlayer insulating film 60, whose end in the vibration end direction D2a is positioned on the vibration end direction D2a side from the end in the vibration end direction D2a of the insulating film 12, forms the vibration region 224 of the vibrating portion 20. In Figure 1, the boundary of the vibration region 224 in the floating region 22 is shown by a dashed line.

[0043] In this embodiment, the vibration region 224 is formed in a shape corresponding to the divided floating region 223, which has a roughly triangular shape in plan view along the stacking direction D1. That is, the vibration region 224 is formed in a roughly triangular shape in plan view, with the vibration end 222 side as the apex and the portion that overlaps with the interlayer opening forming portion 611 in the stacking direction D1 as the base. Hereinafter, as shown in Figure 2, the portion that overlaps with the interlayer opening forming portion 611 in the stacking direction D1 in the upper electrode film 53 will be referred to as the support point portion 225. In this embodiment, the vibration region 224 has a cantilevered shape with the support point portion 225 as the fixed end and the vibration end 222 as the free end.

[0044] The above describes the configuration of the piezoelectric element 1 in this embodiment. When sound pressure is applied to each vibration region 224 of such a piezoelectric element 1, each vibration region 224 vibrates around the pivot point 225. In this case, for example, if the free end side of the vibration region 224 is displaced upward, tensile stress is generated in the lower piezoelectric film 41 and compressive stress is generated in the upper piezoelectric film 42. Therefore, sound pressure is detected by extracting charge from the first electrode portion 31 and the second electrode portion 32 connected by the wiring film 33. The greater the stress generated within the vibration portion 20 due to the vibration of each vibration region 224, the greater the detected voltage value. Furthermore, the higher the voltage value detected when a predetermined sound pressure is applied, the higher the detection sensitivity of the piezoelectric element 1.

[0045] Next, the manufacturing method of the piezoelectric element 1 will be described with reference to Figures 3 to 11. In this embodiment, an example of manufacturing the piezoelectric element 1 using a wafer-shaped support 10 will be described, but the piezoelectric element 1 may also be manufactured using a support 10 that has been divided into chip units in advance.

[0046] First, as shown in Figure 3, a support 10 is prepared in which an insulating film 12 is placed on a support substrate 11. In reality, the support 10 in Figure 3 is a wafer-like structure in which multiple element configuration regions are integrated via dicing lines. Next, as shown in Figure 4, a base film 70 and a lower electrode film 51 are sequentially deposited on the support 10 and patterned into a predetermined shape using a mask (not shown). The base film 70 and the lower electrode film 51 are patterned so as to be placed in the floating region 22. Furthermore, the base film 70 and the lower electrode film 51 are patterned to include a portion connected to the first electrode portion 31 in the stacking direction D1, and a portion facing the second electrode portion 32 in the stacking direction D1. The base film 70 and the lower electrode film 51 are deposited by general sputtering or CVD (Chemical Vapor Deposition) methods. Furthermore, the lower piezoelectric film 41, the middle electrode film 52, the upper piezoelectric film 42, and the upper electrode film 53, which will be described later, are also deposited by general sputtering or CVD methods.

[0047] Next, as shown in Figure 5, the lower piezoelectric film 41 and the middle electrode film 52 are formed. Then, as shown in Figure 6, the upper piezoelectric film 42 is formed to constitute the piezoelectric film 40. In addition, the upper electrode film 53 is formed and patterned into a predetermined shape using a mask (not shown) to constitute the electrode film 50. Then, as shown in Figure 7, etching using a mask (not shown) forms the first electrode hole 311 that exposes the lower electrode film 51, the second electrode hole 321 that exposes the middle electrode film 52, and the separation slit 23 that exposes the insulating film 12.

[0048] Next, as shown in Figure 8, an interlayer insulating film 60 is formed over the entire wafer so as to cover the piezoelectric film 40 and the electrode film 50. Subsequently, as shown in Figure 9, portions corresponding to the interlayer opening 610, the first electrode hole 311, and the second electrode hole 321 are formed by etching using a mask (not shown). When forming the interlayer opening 610 by etching, it is preferable to use anisotropic dry etching, which allows for easier side-etch control compared to wet etching. This is because forming the interlayer opening 610 by anisotropic dry etching makes it easier to suppress positional deviations of the interlayer opening formation portion 611 from the design position due to manufacturing errors.

[0049] Next, as shown in Figure 10, a metal film is deposited to fill the first electrode hole 311 and the second electrode hole 321, thereby forming the first electrode portion 31 and the second electrode portion 32. Then, the metal film deposited on the interlayer insulating film 60 is patterned to form the wiring film 33. This completes the connection portion 30.

[0050] Next, as shown in Figure 11, a mask (not shown) is placed and etching is performed to form the floating opening 100. Specifically, etching is performed to form substrate through holes 110 in the support substrate 11 and insulating through holes 120 in the insulating film 12. Then, the material is divided into chip units along the dicing line. This manufactures the piezoelectric element 1 with the vibrating part 20 placed on the support 10. Note that when forming substrate through holes 110 and insulating through holes 120 in the support 10 in this way, using wet etching rather than anisotropic etching can reduce the difficulty of processing.

[0051] When the undercoat 70 and electrode film 50 are formed on the support 10 by general etching, the coefficients of thermal expansion of the undercoat 70 and electrode film 50 are greater than those of the support 10. Therefore, the undercoat 70 and electrode film 50 are formed with residual tensile stress. Consequently, when the piezoelectric film 40 and interlayer insulating film 60 are formed on the piezoelectric film 40, the piezoelectric film 40 and interlayer insulating film 60 are formed with residual tensile stress caused by the tensile stress of the undercoat 70 and electrode film 50. In other words, the interlayer insulating film 60 is formed with tensile stress generated internally.

[0052] Next, the reason why the end of the interlayer insulating film 60 in the vibration end direction D2a is positioned closer to the vibration end direction D2a than the end of the insulating film 12 in the vibration end direction D2a will be explained using the comparative piezoelectric element 1X of the comparative example shown in Figure 12. The comparative piezoelectric element 1X shown in Figure 12 has a comparative interlayer insulating film 60X that corresponds to the interlayer insulating film 60 of the piezoelectric element 1 of this embodiment. The size of the comparative interlayer opening 610X, which corresponds to the interlayer opening 610, is formed to be larger than the interlayer opening 610. As a result, in the comparative piezoelectric element 1X, the end of the comparative interlayer insulating film 60X in the vibration end direction D2a is positioned closer to the support end direction D2b than the end of the insulating film 12 in the vibration end direction D2a. In addition, in the comparative piezoelectric element 1X, similar to the piezoelectric element 1 of this embodiment, the ends of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 on the support end direction D2b side overlap with the insulating film 12 in the stacking direction D1.

[0053] As described above, the piezoelectric element 1 detects the stress generated within the piezoelectric film 40 when sound pressure is applied and each vibration region 224 vibrates. In the comparative piezoelectric element 1X, where the end of the comparative interlayer insulating film 60X in the vibration end direction D2a is positioned on the support end direction D2b side of the end of the insulating film 12 in the vibration end direction D2a, the fulcrum when the floating region 22 vibrates is the part that overlaps with the insulating hole forming portion 121. That is, the fulcrum when the floating region 22 vibrates is the support end portion 221.

[0054] Therefore, when the floating region 22 vibrates, the stress generated in the vibrating portion 20 is concentrated in the areas of the piezoelectric film 40 and electrode film 50 that overlap with the insulating hole forming portion 121 in the stacking direction D1, as shown in Figure 13. The dashed line in Figure 13 indicates the boundary between the support region 21 and the floating region 22. Accordingly, in the comparative piezoelectric element 1X where the ends on the support end direction D2b side of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 overlap with the insulating film 12 in the stacking direction D1, the charge in the stress-concentrated area of ​​the piezoelectric film 40 is extracted via the electrode film 50.

[0055] Furthermore, as described above, the higher the voltage value detected when a predetermined sound pressure is applied, the higher the detection sensitivity of the comparative piezoelectric element 1X. Therefore, by extracting the charge from areas where stress is concentrated and high stress is generated, the higher the voltage value detected from the electrode film 50, the higher the detection sensitivity of the comparative piezoelectric element 1X can be.

[0056] However, when etching is performed to form floating openings 100 in the support 10, the position of the insulating hole formation portion 121, which is the inner edge of the insulating film 12, may deviate from the design position due to manufacturing errors or other reasons. In other words, when insulating through holes 120 are formed in the insulating film 12 by etching, the inner diameter of the insulating hole formation portion 121 may deviate from the design value. In particular, such deviations from the design position tend to be larger when using wet etching, which is more difficult to control side etching compared to anisotropic etching. Furthermore, the positional deviation of the insulating hole formation portion 121 becomes a factor in the shifting of the pivot point when the floating region 22 vibrates.

[0057] For example, as shown by the dashed line in Figure 14, if the position of the insulating hole forming portion 121 shifts toward the support end direction D2b, the position of the pivot point when the floating region 22 vibrates will shift toward the support end direction D2b from the design position. Furthermore, if the position of the pivot point when the floating region 22 vibrates shifts to a position that does not overlap with the electrode film 50 in the stacking direction D1, the floating region 22 will not have the electrode film 50 supported by the insulating film 12, and only the piezoelectric film 40 will be supported by the insulating film 12.

[0058] In this case, as shown in Figure 14, the stress generated in the vibrating portion 20 when the floating region 22 vibrates is also generated on the support end side D2b from the design position of the insulating hole forming portion 121. Therefore, the stress in the portion of the piezoelectric film 40 that overlaps with the electrode film 50 decreases. Consequently, when the comparative piezoelectric element 1X extracts charge from the piezoelectric film 40 via the electrode film 50, the voltage detected from the electrode film 50 decreases compared to when the position of the insulating hole forming portion 121 is the design position.

[0059] In contrast, in this embodiment, the piezoelectric element 1 has an end of the interlayer insulating film 60 in the vibration end direction D2a positioned closer to the vibration end direction D2a than the end of the insulating film 12 in the vibration end direction D2a. When configured in this way, the pivot point when each vibration region 224 vibrates becomes the pivot point 225 that coincides with the interlayer opening forming portion 611 in the upper electrode film 53 in the stacking direction D1. Therefore, even if the position of the insulating hole forming portion 121 shifts towards the support end direction D2b due to manufacturing errors, and the end of the insulating film 12 on the support end direction D2b side shifts to a position where it does not coincide with the electrode film 50 in the stacking direction D1, the position of the pivot point when each vibration region 224 vibrates does not shift. Thus, it is possible to avoid the shift in the area where stress concentrates due to the position of the insulating hole forming portion 121 shifting from the design position, and it is possible to suppress a decrease in the voltage detected from the electrode film 50. Therefore, the piezoelectric element 1 with the above configuration can improve detection sensitivity.

[0060] Furthermore, according to the above embodiment, the following effects can be obtained.

[0061] (1) In the above embodiment, the entire end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a.

[0062] According to this, even if the position of the insulating hole formation portion 121 is shifted in any direction, including the support end direction D2b component, due to manufacturing errors or the like, the position of the pivot point when each vibration region 224 vibrates will not shift. Therefore, it is possible to avoid shifts in areas where stress concentrates due to the position of the insulating hole formation portion 121 being shifted from the design position, and it is possible to suppress a decrease in the voltage detected from the electrode film 50. Therefore, it is easier to ensure the detection sensitivity of the piezoelectric element 1 compared to a configuration in which a part of the end of the interlayer insulating film 60 in the vibration end direction D2a is positioned on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a.

[0063] (2) In the above embodiment, at least a portion of the end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the electrode film 50 on the support end direction D2b side.

[0064] According to this, the stress generated in the vibrating part 20 when the vibration region 224 vibrates can be concentrated in the portion of the piezoelectric film 40 and electrode film 50 that overlaps with the interlayer opening 610 in the lamination direction D1. As a result, the piezoelectric element 1 can extract the charge from the stress-concentrated portion of the piezoelectric film 40, further improving the detection sensitivity.

[0065] Furthermore, by configuring the interlayer insulating film 60 to overlap with the electrode film 50 in the stacking direction D1, the rigidity of the support portion 225 can be increased compared to a configuration in which the interlayer insulating film 60 and the electrode film 50 do not overlap. As a result, buckling of the vibrating portion 20 can be made less likely.

[0066] (3) In the above embodiment, the electrode film 50 includes a lower electrode film 51, a middle electrode film 52, and an upper electrode film 53 that are stacked in the stacking direction D1 via the piezoelectric film 40. The end of the interlayer insulating film 60 in the vibration end direction D2a is positioned on the vibration end direction D2a side of the end of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 on the support end direction D2b side.

[0067] According to this, even in a configuration in which multiple electrode films 50 are stacked in such a way, it is possible to extract the charge from the stress-concentrated areas in the piezoelectric film 40, thereby further improving the detection sensitivity.

[0068] (4) In the above embodiment, the interlayer insulating film 60 is formed by tensile stress.

[0069] If compressive stress occurs as internal stress in the vibration region 224, the vibration region 224 may buckle and become structurally rigid, potentially reducing the detection sensitivity. In contrast, by forming the interlayer insulating film 60 with tensile stress, the reduction in detection sensitivity due to buckling can be suppressed.

[0070] (5) By using the piezoelectric element 1 of this embodiment in a microphone, a microphone with high detection sensitivity can be made.

[0071] (First modification of the first embodiment) In the first embodiment described above, an example was described in which the entire end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a. In the first embodiment described above, an example was described in which the entire end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the electrode film 50 in the support end direction D2b. However, the shape of the interlayer insulating film 60 is not limited to these.

[0072] For example, the interlayer insulating film 60 may be positioned such that only a portion of its end in the vibration end direction D2a is located on the D2a side of the vibration end direction compared to the D2b side of the end of the insulating film 12 and the electrode film 50, respectively. Alternatively, the remaining portion of the interlayer insulating film 60's end in the vibration end direction D2a may be positioned on the D2b side of the end of the insulating film 12 and the electrode film 50, respectively.

[0073] In this case, for example, as shown in Figures 15 and 16, the interlayer insulating film 60 may be formed in a shape having an interlayer projection 61 that protrudes toward the vibration end direction D2a. The interlayer projection 61 may be formed such that its width in the direction perpendicular to the vibration end direction D2a and the lamination direction D1 decreases continuously toward the vibration end direction D2a, as shown in Figure 15. Alternatively, as shown in Figure 16, the interlayer insulating film 60 may be formed such that its width in the direction perpendicular to the vibration end direction D2a and the lamination direction D1 decreases in steps toward the vibration end direction D2a.

[0074] According to this, the stress generated in the vibrating portion 20 when the vibration region 224 vibrates can be concentrated in the portion of the piezoelectric film 40 and electrode film 50 that overlaps with the interlayer protrusion 61 in the stacking direction D1. As a result, the piezoelectric element 1 can extract the charge from the stress-concentrated portion of the piezoelectric film 40, thereby further improving the detection sensitivity.

[0075] (Second modification of the first embodiment) In the first embodiment described above, an example was described in which the end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53, respectively, on the support end direction D2b side. However, the invention is not limited to this example.

[0076] For example, the interlayer insulating film 60 may be configured such that its end in the vibration end direction D2a is located on the vibration end direction D2a side of one or two of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 ends on the support end direction D2b side.

[0077] (Second Embodiment) Next, the second embodiment will be described with reference to Figure 17. In this embodiment, the shapes of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 differ from those of the first embodiment. Also, in this embodiment, the shape of the interlayer insulating film 60 differs from that of the first embodiment due to the changes in the shapes of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53. Other than these differences, it is the same as the first embodiment. For this reason, in this embodiment, we will mainly describe the parts that differ from the first embodiment, and we may omit the description of parts that are the same as the first embodiment.

[0078] As shown in Figure 17, in this embodiment, each vibration region 224 is defined as a first region R1 on the fixed end side and a second region R2 on the free end side. The lower electrode film 51, middle electrode film 52, and upper electrode film 53 are formed in the first region R1 and the second region R2, respectively. However, the lower electrode film 51, middle electrode film 52, and upper electrode film 53 formed in the first region R1 are separated from the lower electrode film 51, middle electrode film 52, and upper electrode film 53 formed in the second region R2, and are in an insulated state.

[0079] Furthermore, as shown in Figure 17, the upper electrode film 53 formed in the second region R2 is formed in a planar triangular shape. Although not shown, the lower electrode film 51 and the middle electrode film 52 formed in the second region R2 are also formed in a planar triangular shape, similar to the upper electrode film 53. In addition, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 formed in the second region R2 are each formed to overlap each other in the stacking direction D1. That is, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 formed in the second region R2 have the same shape and are positioned to overlap in the stacking direction D1.

[0080] Furthermore, the upper electrode film 53 formed in the first region R1 is divided into multiple parts. Specifically, the upper electrode film 53 formed in the first region R1 is divided into three substantially trapezoidal shapes with different shapes by two electrode slits 54. The electrode slits 54 are formed penetrating the upper electrode film 53 in the stacking direction D1. The two electrode slits 54 are formed to extend toward the center C from two points that divide the base of the substantially isosceles triangular upper electrode film 53 into three equal parts. The two electrode slits 54 formed in this way do not intersect each other. Hereinafter, the parts of the upper electrode film 53 formed in the first region R1 that are divided into three by the two electrode slits 54 will be referred to as the first base film 531, the second base film 532, and the third base film 533. The first base film 531, the second base film 532, and the third base film 533 are arranged in this order in the vibration region 224. The first base membrane 531, the second base membrane 532, and the third base membrane 533 correspond to the divided electrode membranes separated by the electrode slit 54.

[0081] Although not shown in the diagram, the lower electrode film 51 and the middle electrode film 52 formed in the first region R1 are similarly divided into three parts by two slits. The lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 formed in the first region R1 are each formed to overlap each other in the stacking direction D1. That is, the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 formed in the first region R1 have the same shape and are positioned to overlap in the stacking direction D1. In Figure 17, only representative parts of the multiple electrode slits 54, the first base film 531, the second base film 532, and the third base film 533 are shown by their symbols, and other symbols are omitted.

[0082] Furthermore, as shown in Figure 17, the interlayer insulating film 60 of this embodiment has an interlayer projection 62 that protrudes in the vibration end direction D2a and is positioned across the upper piezoelectric film 42 and the upper electrode film 53. Specifically, the interlayer insulating film 60 has a first interlayer projection 621, a second interlayer projection 622, and a third interlayer projection 623 that protrude in the vibration end direction D2a toward the first base film 531, the second base film 532, and the third base film 533, respectively. The interlayer insulating film 60 also has an interlayer recess 63 that is recessed toward the support end direction D2b from these first interlayer projections 621, 622, and 623.

[0083] The first interlayer protrusion 621 is positioned across the upper piezoelectric film 42 and the first base film 531. The second interlayer protrusion 622 is positioned across the upper piezoelectric film 42 and the second base film 532. The third interlayer protrusion 623 is positioned across the upper piezoelectric film 42 and the third base film 533. Therefore, the ends of the first interlayer protrusion 621, the second interlayer protrusion 622, and the third interlayer protrusion 623 on the vibration end direction D2a side are positioned closer to the vibration end direction D2a than the ends of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 on the support end direction D2b. In addition, the ends of the first interlayer protrusion 621, the second interlayer protrusion 622, and the third interlayer protrusion 623 on the vibration end direction D2a side protrude closer to the vibration end direction D2a than the end of the insulating film 12 in the vibration end direction D2a.

[0084] The interlayer recesses 63 are formed between the first interlayer protrusions 621, the second interlayer protrusions 622, and the third interlayer protrusions 623, respectively. In other words, the interlayer recesses 63 are formed between the first base layer 531, the second base layer 532, and the third base layer 533 in the upper electrode film 53. Furthermore, the interlayer recesses 63 are formed in a position that does not overlap with the electrode slits 54 in the stacking direction D1.

[0085] Furthermore, the interlayer recess 63 is located on the upper piezoelectric film 42 and not on the upper electrode film 53. For this reason, the end of the interlayer recess 63 on the vibration end direction D2a is positioned on the support end direction D2b side of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53, respectively. In addition, the end of the interlayer recess 63 on the vibration end direction D2a is recessed on the support end direction D2b side of the insulating film 12 than the end on the vibration end direction D2a side.

[0086] The interlayer opening 610 that exposes the upper electrode film 53 is formed by the first interlayer protrusion 621, the second interlayer protrusion 622, the third interlayer protrusion 623, and the interlayer recess 63. The interlayer opening 610 is formed by the interlayer protrusion 62 and the interlayer recess 63 being arranged alternately. Therefore, the interlayer opening forming portion 611 that forms the interlayer opening 610 in this embodiment has an uneven shape with the interlayer protrusion 62 and the interlayer recess 63 being arranged alternately.

[0087] As shown in Figure 17, the interlayer insulating film 60 formed in this manner has the end of the interlayer protrusion 62 in the vibration end direction D2a positioned on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a. Furthermore, the interlayer insulating film 60 has the interlayer recess 63 positioned on the support end direction D2b side of the end of the insulating film 12 in the vibration end direction D2a, and does not overlap with the insulating film 12 in the lamination direction D1. In other words, in this embodiment, a portion of the end of the interlayer insulating film 60 in the vibration end direction D2a is positioned on the vibration end direction D2a side of the end of the insulating film 12 in the vibration end direction D2a, and the remaining portion is positioned on the support end direction D2b side of the end of the insulating film 12 in the vibration end direction D2a.

[0088] Furthermore, the interlayer insulating film 60 has its interlayer protrusions 62 positioned on the vibration end direction D2a side of the support end direction D2b of the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53, respectively. In other words, the interlayer protrusions 62 overlap with the lower electrode film 51, the middle electrode film 52, and the upper electrode film 53 in the stacking direction D1.

[0089] Specifically, the end of the first interlayer protrusion 621 on the vibration end direction D2a is positioned closer to the vibration end direction D2a than the end of the first base film 531 on the support end direction D2b. Although not shown in the figures, the end of the first interlayer protrusion 621 on the vibration end direction D2a is also positioned closer to the vibration end direction D2a than the end of the portion of the lower electrode film 51 and the middle electrode film 52 that overlaps with the first base film 531 in the stacking direction D1, on the support end direction D2b.

[0090] The end of the second interlayer protrusion 622 on the vibration end direction D2a is positioned closer to the vibration end direction D2a than the end of the second base film 532 on the support end direction D2b. Although not shown in the figures, the end of the second interlayer protrusion 622 on the vibration end direction D2a is also positioned closer to the vibration end direction D2a than the end of the portion of the lower electrode film 51 and the middle electrode film 52 that overlaps with the second base film 532 in the stacking direction D1, on the support end direction D2b.

[0091] The end of the third interlayer protrusion 623 on the vibration end direction D2a is positioned closer to the vibration end direction D2a than the end of the third base film 533 on the support end direction D2b. Although not shown in the figures, the end of the third interlayer protrusion 623 on the vibration end direction D2a is also positioned closer to the vibration end direction D2a than the end of the portion of the lower electrode film 51 and the middle electrode film 52 that overlaps with the third base film 533 in the stacking direction D1, on the support end direction D2b.

[0092] In this configuration, the pivot point for each vibration region 224 when it vibrates is the portion that overlaps with the interlayer protrusion 62 in the upper electrode film 53 in the stacking direction D1. Therefore, even if the position of the insulating hole forming portion 121 shifts toward the support end direction D2b due to manufacturing errors, and the end of the insulating film 12 toward the support end direction D2b shifts to a position where it does not overlap with the electrode film 50 in the stacking direction D1, the position of the pivot point for each vibration region 224 when it vibrates will not shift. Consequently, the shift in the area where stress concentrates due to the position of the insulating hole forming portion 121 shifting from the design position can be avoided, and a decrease in the voltage detected from the electrode film 50 can be suppressed. Therefore, the piezoelectric element 1 with the above configuration can improve detection sensitivity.

[0093] Furthermore, when the vibration region 224 vibrates, stress is less likely to occur in the parts of the piezoelectric film 40 and electrode film 50 that overlap with the interlayer recess 63 in the stacking direction D1. Therefore, the stress generated in the vibration region 224 can be further concentrated in the parts of the piezoelectric film 40 and electrode film 50 that overlap with the interlayer protrusion 62 in the stacking direction D1. As a result, the piezoelectric element 1 can extract the charge from the stress-concentrated parts of the piezoelectric film 40, further improving detection sensitivity.

[0094] Furthermore, according to the above embodiment, the following effects can be obtained.

[0095] (1) In the above embodiment, the electrode film 50 is divided into a first base film 531, a second base film 532, and a third base film 533 by an electrode slit 54 on the support end direction D2b side. The interlayer insulating film 60 includes an interlayer convex portion 62 that protrudes in the vibration end direction D2a and an interlayer recess 63 that is recessed in the support end direction D2b. The end of the interlayer convex portion 62 in the vibration end direction D2a is positioned on the D2a side of the vibration end direction compared to the end of each of the divided first base film 531, second base film 532, and third base film 533 on the D2b side of the support end direction. The interlayer recess 63 is formed in a position that does not overlap with the electrode slit 54 and is positioned on the D2b side of the support end direction compared to the end of each of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 in the D2b direction.

[0096] As described above, the detection sensitivity of the piezoelectric element 1 can be improved by extracting the charge from the stress-concentrated area in the piezoelectric film 40 via the electrode film 50. However, in the area of ​​the piezoelectric film 40 that overlaps with the electrode slit 54 in the stacking direction D1, the electrode film 50 is not present, and therefore, charge cannot be extracted from that area. For this reason, if stress is concentrated in the area of ​​the piezoelectric film 40 that overlaps with the electrode slit 54 in the stacking direction D1, this concentrated stress cannot be used for sound pressure detection.

[0097] In contrast, as in this embodiment, by forming the interlayer recess 63 at a position that does not overlap with the electrode slit 54, stress is less likely to occur in the portion of the piezoelectric film 40 that overlaps with the electrode slit 54 in the stacking direction D1. Furthermore, stress can be further concentrated in the portion of the piezoelectric film 40 that overlaps with the interlayer protrusion 62 in the stacking direction D1. As a result, the piezoelectric element 1 can extract the charge from the portion of the piezoelectric film 40 where stress is further concentrated, thus further improving the detection sensitivity.

[0098] (Modified version of the second embodiment) In the second embodiment described above, an example was described in which the interlayer insulating film 60 includes an interlayer protrusion 62 projecting in the vibration end direction D2a and an interlayer recess 63 recessed in the support end direction D2b, but the invention is not limited thereto. For example, as shown in Figure 18, the interlayer insulating film 60 does not include an interlayer protrusion 62 and an interlayer recess 63, and the entire end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of each of the multiple divided first base film 531, second base film 532, and third base film 533 on the support end direction D2b side.

[0099] (Third embodiment) Next, a third embodiment will be described with reference to Figure 19. In this embodiment, the shape of the support substrate 11 differs from that of the first embodiment. Otherwise, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0100] As shown in Figure 19, in this embodiment, the size of the through-holes 110 in the support substrate 11 is larger than the size of the through-holes 110 in the substrate through-holes 110 described in the first embodiment. In other words, the cross-sectional area of ​​the through-holes 110 perpendicular to the stacking direction D1 is larger than the cross-sectional area of ​​the through-holes 110 perpendicular to the stacking direction D1 described in the first embodiment.

[0101] As a result, the support substrate 11 has a shape that does not overlap with the electrode film 50 in the stacking direction D1. That is, the substrate hole forming portion 111, which is the inner edge of the support substrate 11, is positioned closer to the support end direction D2b than the end of the electrode film 50 on the support end direction D2b side. In other words, the end of the electrode film 50 on the support end direction D2b side is positioned closer to the vibration end direction D2a than the end of the support substrate 11 on the vibration end direction D2a side. In this embodiment, the entire ends of the lower electrode film 51, middle electrode film 52, and upper electrode film 53 on the support end direction D2b are positioned closer to the vibration end direction D2a than the end of the support substrate 11 on the vibration end direction D2a side.

[0102] The reason why the end of the electrode film 50 in the vibration end direction D2a is positioned closer to the vibration end direction D2a than the end of the support substrate 11 in the vibration end direction D2a is explained below.

[0103] When the electrode film 50 and the support substrate 11 are positioned to overlap in the stacking direction D1, parasitic capacitance may occur between the electrode film 50 and the support substrate 11. If parasitic capacitance occurs between the electrode film 50 and the support substrate 11, and the potential of the piezoelectric film 40 decreases when the piezoelectric film 40 vibrates, the detection sensitivity of the piezoelectric element 1 when detecting sound waves may decrease.

[0104] In contrast, in the piezoelectric element 1 of this embodiment, the end of the electrode film 50 in the vibration end direction D2a is positioned on the vibration end direction D2a side of the end of the support substrate 11 in the vibration end direction D2a. As a result, the support substrate 11 and the electrode film 50 do not overlap in the stacking direction D1, so it is possible to avoid the generation of parasitic capacitance between the electrode film 50 and the support substrate 11. This also prevents the potential of the piezoelectric film 40 from decreasing due to the generation of parasitic capacitance. As a result, the detection sensitivity of the piezoelectric element 1 when detecting sound waves can be improved compared to a configuration in which the support substrate 11 and the electrode film 50 overlap in the stacking direction D1.

[0105] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with either the first or second embodiment described above.

[0106] (Fourth Embodiment) Next, the fourth embodiment will be described with reference to Figure 20. In this embodiment, the shape of the interlayer insulating film 60 differs from that of the first embodiment. Otherwise, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0107] As shown in Figure 20, the interlayer insulating film 60 of this embodiment is formed with a larger size in the stacking direction D1 compared to the interlayer insulating film 60 described in the first embodiment. As a result, the interlayer insulating film 60 is formed with a size such that the bending stiffness in the stacking direction D1 is greater than the bending stiffness in the stacking direction D1 of the portion of the vibrating section 20 that is on the vibrating end side D2a of the portion where the interlayer insulating film 60 is located. In other words, the interlayer insulating film 60 is formed with a size such that the bending stiffness in the stacking direction D1 is greater than the bending stiffness in the stacking direction D1 of the portion formed by the piezoelectric film 40 and the electrode film 50.

[0108] Incidentally, bending stiffness can generally be determined by multiplying the Young's modulus of a member by its second moment of area. Therefore, when a vibration region 224 vibrates with the end of the interlayer insulating film 60 in the vibration end direction D2a as a fulcrum, the bending stiffness of the vibration region 224 can be determined based on the Young's modulus and second moment of area of ​​the portion on the D2a side of the vibration end direction from the portion where the interlayer insulating film 60 is located.

[0109] Furthermore, the portion of the vibrating section 20 located on the D2a side in the direction of the vibration end, relative to the portion where the interlayer insulating film 60 is positioned, is formed by the piezoelectric film 40 and the electrode film 50. Therefore, the Young's modulus of this portion is the equivalent Young's modulus, which can be calculated from the Young's moduli of the piezoelectric film 40 and the electrode film 50, respectively. Consequently, the bending stiffness of the vibrating region 224 can be determined based on this equivalent Young's modulus and the second moment of area of ​​the vibrating region 224.

[0110] Furthermore, the cross-sectional area perpendicular to the support end direction D2b in the portion of the vibrating section 20 that is located on the side of the vibrating end direction D2a from the portion where the interlayer insulating film 60 is positioned is rectangular. Therefore, the second moment of area of ​​the vibrating region 224 can be calculated based on the magnitude of the stacking direction D1 of the piezoelectric film 40 and the electrode film 50, respectively.

[0111] Furthermore, the bending stiffness of the interlayer insulating film 60 can be determined based on the Young's modulus and the second moment of area of ​​the interlayer insulating film 60. The cross-sectional area of ​​the interlayer insulating film 60 perpendicular to the support end direction D2b is rectangular. Therefore, the second moment of area of ​​the interlayer insulating film 60 can be calculated based on the magnitude of the lamination direction D1 of the interlayer insulating film 60.

[0112] Based on the above, the magnitude of the lamination direction D1 of the interlayer insulating film 60 in this embodiment is set such that the bending stiffness of the interlayer insulating film 60 in the lamination direction D1 is greater than the bending stiffness of the lamination direction D1 in the vibration region 224.

[0113] In this embodiment, the piezoelectric film 40 is made of ScAlN, as described above. The Young's modulus of ScAlN is approximately 200 GPa. The electrode film 50 in this embodiment is made of Mo, which has a Young's modulus of approximately 330 GPa. The equivalent Young's modulus of the vibration region 224, composed of the piezoelectric film 40 made of ScAlN and the electrode film 50 made of Mo, is 200 to 300 GPa. The vibration region 224 has a size of approximately 1 μm in the stacking direction D1.

[0114] In contrast, the interlayer insulating film 60 in this embodiment is composed of an oxide film. The Young's modulus of the oxide film is approximately 60 GPa. When the bending stiffness of the interlayer insulating film 60 in the lamination direction D1 is to be greater than the bending stiffness in the vibration region 224, the size of the interlayer insulating film 60 in the lamination direction D1 needs to be about 3.3 to 5 μm. For this reason, the interlayer insulating film 60 in this embodiment is formed with a size in the lamination direction D1 that is greater than 5 μm.

[0115] As described above, the bending stiffness of the interlayer insulating film 60 in this embodiment is set to be greater in the lamination direction D1 than the bending stiffness in the lamination direction D1 of the portion of the vibrating portion 20 that is on the vibrating end side D2a of the portion where the interlayer insulating film 60 is located. Therefore, the position of the interlayer opening forming portion 611, which acts as a fulcrum when the vibrating portion 20 vibrates, is difficult to change, and buckling of the vibrating portion 20 is less likely to occur. As a result, displacement of the stress concentration area caused by the position of the interlayer opening forming portion 611 deviating from the design position can be avoided, and a decrease in the voltage detected from the electrode film 50 can be suppressed. Consequently, the detection sensitivity of the piezoelectric element 1 can be further improved. In addition, a decrease in detection sensitivity due to buckling can be suppressed.

[0116] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the first to third embodiments described above.

[0117] (Fifth embodiment) Next, the fifth embodiment will be described with reference to Figure 21. In this embodiment, the components constituting the interlayer insulating film 60 differ from those in the first embodiment. Otherwise, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0118] As shown in Figure 21, the interlayer insulating film 60 in this embodiment is made of a different material than the interlayer insulating film 60 described in the first embodiment. Furthermore, the interlayer insulating film 60 in this embodiment is made of a material whose Young's modulus is greater than that of the portion of the vibrating section 20 on the D2a side in the direction of the vibration end from the portion where the interlayer insulating film 60 is located. In other words, the interlayer insulating film 60 is made of a material whose Young's modulus is greater than that of the portion formed by the piezoelectric film 40 and the electrode film 50. Here, as described above, the equivalent Young's modulus of the vibrating region 224, which is made of the piezoelectric film 40 made of ScAlN and the electrode film 50 made of Mo, is 200 to 300 GPa.

[0119] In contrast, the interlayer insulating film 60 in this embodiment is composed of silicon nitride (SiN), which has a Young's modulus greater than the equivalent Young's modulus of the vibration region 224. Alternatively, the interlayer insulating film 60 may be composed of aluminum nitride (ALN), aluminum oxide (AL2O3), etc., which have a Young's modulus greater than the equivalent Young's modulus of the vibration region 224. The Young's modulus of SiN is approximately 300 GPa. The Young's modulus of ALN is approximately 320 GPa. The Young's modulus of AL2O3 is approximately 360 GPa.

[0120] According to this, even if the bending stiffness of the interlayer insulating film 60 in the stacking direction D1 is greater than the bending stiffness of the vibration region 224, the size of the interlayer insulating film 60 in the stacking direction D1 can be made smaller than the size of the stacking direction D1 of the vibration region 224. Therefore, the size of the piezoelectric element 1 in the stacking direction D1 can be suppressed, and the manufacturing cost of the piezoelectric element 1 can be reduced.

[0121] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the first to third embodiments described above.

[0122] (Other embodiments) While typical embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0123] In the above-described embodiment, an example was described in which the vibrating unit 20 has a lower piezoelectric film 41, an upper piezoelectric film 42, a lower electrode film 51, a middle electrode film 52, and an upper electrode film 53, but it is not limited to this. The vibrating unit 20 only needs to have a configuration that includes at least one piezoelectric film 40 and one electrode film 50.

[0124] In the above-described embodiment, an example was given in which the piezoelectric element 1 is formed in a rectangular shape when viewed in a direction perpendicular to the stacking direction D1, but the invention is not limited to this. For example, the piezoelectric element 1 may have a polygonal shape such as a pentagon or a hexagon when viewed in a direction perpendicular to the stacking direction D1.

[0125] In the above-described embodiment, an example was given in which the vibrating section 20 is divided into four vibrating regions 224 by the separation slit 23, but the invention is not limited to this. For example, the vibrating section 20 may be divided into three or fewer vibrating regions 224 by the separation slit 23, or it may be divided into five or more vibrating regions 224.

[0126] In the embodiments described above, an example was described in which at least a portion of the end of the interlayer insulating film 60 in the vibration end direction D2a is located on the vibration end direction D2a side of the end of the electrode film 50 in the support end direction D2b, but the invention is not limited to this.

[0127] As long as the interlayer insulating film 60 has a shape such that at least a portion of its end in the vibration end direction D2a is located on the vibration end direction D2a side of the insulating film 12 in the vibration end direction D2a, the entire end in the vibration end direction D2a may be located on the support end direction D2b side of the electrode film 50 in the support end direction D2b side, as shown in Figure 22.

[0128] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0129] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0130] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc. [Explanation of Symbols]

[0131] 10 Support 11 Support substrate 12 Insulating film 20 Vibration section 21 Support area 22. Floating Area 40 Piezoelectric film 50 Electrode membrane 60 Interlayer insulating film 100 Floating opening

Claims

1. Piezoelectric element, Support (10) and It comprises a vibrating part (20) which is stacked on the support along a predetermined stacking direction and vibrates when pressure is applied from the outside, The vibrating portion includes a piezoelectric film (40) disposed on the support, an electrode film (50) disposed on the piezoelectric film, and an interlayer insulating film (60) disposed on the piezoelectric film, and also has a support region (21) supported by the support, and a floating region (22) connected to the support region and floating away from the support. The floating region has a fixed end (221) that forms the boundary with the support region, and a free end (222) that vibrates on the opposite side of the support end. The support comprises a support substrate (11) and an insulating film (12) disposed on the support substrate and on which the vibrating portion is arranged, and a floating opening (100) is formed in the support substrate and the insulating film to allow the floating region to float. A piezoelectric element in which, when the direction from the support end toward the vibrating end is defined as the vibration end direction, at least a portion of the end in the vibration end direction is positioned on the side of the vibration end direction relative to the end of the insulating film in the vibration end direction.

2. The piezoelectric element according to claim 1, wherein the entire end of the interlayer insulating film in the direction of vibration is located on the side of the end of the insulating film in the direction of vibration that is further toward the end of the insulating film in the direction of vibration.

3. The piezoelectric element according to claim 1 or 2, wherein, when the direction from the vibrating end toward the support end is defined as the support end direction, at least a portion of the end of the interlayer insulating film in the vibrating end direction is positioned on the vibrating end direction side of the end of the electrode film on the support end direction side.

4. The electrode films are stacked in multiple layers in the stacking direction via the piezoelectric film, The piezoelectric element according to claim 1 or 2, wherein, when the direction from the vibrating end toward the support end is defined as the support end direction, at least a portion of the end of the interlayer insulating film in the vibrating end direction is positioned toward the vibrating end direction more toward the vibrating end direction than the end of at least one of the electrode films among the plurality of electrode films that is on the support end direction side.

5. The piezoelectric element according to claim 1 or 2, wherein, when the direction from the vibrating end toward the support end is defined as the support end direction, a portion of the end of the interlayer insulating film in the vibrating end direction is positioned on the vibrating end direction side of the electrode film on the support end direction side, and the remaining portion of the end in the vibrating end direction is positioned on the support end direction side of the electrode film on the support end direction side.

6. The electrode film includes a plurality of divided electrode films (531, 532, 533) that are divided by an electrode slit (54) on the side toward the support end, The interlayer insulating film includes an interlayer protrusion (62) that protrudes in the direction of the vibration end and an interlayer recess (63) that is recessed toward the direction of the support end, when the direction from the vibration end toward the support end is defined as the support end direction. The end of the interlayer protrusion in the direction of vibration is positioned on the vibration end side of each of the multiple divided electrode films, The piezoelectric element according to claim 1 or 2, wherein the interlayer recess is formed in a position that does not overlap with the electrode slit, and is located on the side of the support end direction from the end of each of the plurality of electrode films on the support end direction side.

7. The piezoelectric element according to claim 1, wherein, when the direction from the vibrating end toward the support end is defined as the support end direction, the end of the electrode film on the support end direction side is positioned on the vibrating end direction side of the support substrate in the vibrating end direction.

8. The piezoelectric element according to claim 1, wherein the interlayer insulating film is formed by tensile stress.

9. The piezoelectric element according to claim 1, wherein the bending stiffness of the interlayer insulating film in the stacking direction is greater than the bending stiffness in the stacking direction of the portion of the vibrating portion that is on the side of the vibrating end direction than the portion of the vibrating portion where the interlayer insulating film is arranged.

10. The piezoelectric element according to claim 1, wherein the Young's modulus of the interlayer insulating film is greater than the equivalent Young's modulus of the portion of the vibrating portion that is on the side of the vibrating end direction than the portion of the vibrating portion where the interlayer insulating film is located.

11. A microphone comprising a piezoelectric element according to any one of claims 1 to 11.

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