Piezoelectric element, microphone, and method for manufacturing piezoelectric element

Abstract

To provide a piezoelectric element, a microphone, and a method of manufacturing the piezoelectric element capable of reducing an increase in man-hours.SOLUTION: A piezoelectric element includes: a piezoelectric film 40 arranged on a support 10; an electric film 50 laminated on the piezoelectric film 40; through electrodes 61a, 62a formed inside hole parts 61b, 62b penetrating the piezoelectric film 40; and an interlayer insulating film 82 which is formed on the wall surfaces of the holes 61a and 62a and on the top of the piezoelectric film 40, and insulates the piezoelectric film 40 from the through electrodes 61b, 62b. A vibrating part 20 includes a piezoelectric film 40 and an electrode film 50, and has a support region 21a supported by the support 10 and a floating region 21b floating from the support 10. The floating region 21b has a plurality of vibration regions partitioned by slits 30, and in the slits 30, an additional thin film 81 made of the same material as the interlayer insulating film 82 is arranged.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric element, a microphone, and a method for manufacturing a piezoelectric element. [Background technology]

[0002] Piezoelectric MEMS (Micro Electro Mechanical Systems) microphones are composed of a piezoelectric element with a layered structure of electrodes and piezoelectric film. In the manufacturing process of piezoelectric elements, a lower electrode is formed over the entire top surface of a substrate, and after a portion is removed by patterning, a piezoelectric film is formed on top of the lower electrode. An upper electrode is then formed on top of this piezoelectric film. A via is formed in the piezoelectric film to expose the lower electrode, and the potential of the lower electrode is extracted through wiring formed in this via. Furthermore, an opening is formed in the substrate, and a slit is formed in the layered structure of the electrodes and piezoelectric film, so that this layered structure is cantilevered at the open edge of the substrate and serves as a vibration region.

[0003] The crystallinity of the piezoelectric film formed in the area where the electrode was removed deteriorates, and stress concentration at the electrode end may cause cracks, resulting in a decrease in resistance. If leakage occurs between the electrodes through the area where the resistance is reduced, dielectric loss increases, resulting in increased microphone noise, so it is necessary to block the leakage. An interlayer insulating film is usually used for this purpose (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-74836 Summary of the Invention [Problem to be solved by the invention]

[0005] In such microphones, the vibration area vibrates when pressure such as sound pressure is applied, and the charge generated in the piezoelectric film is output as a detection signal, but residual stress generated during manufacturing can deform the vibration area, widening the slit and allowing pressure to escape, which can narrow the detection band.In response to this, the inventors proposed in Japanese Patent Application No. 2021-152427 a piezoelectric element that suppresses the widening of the slit by forming an additional thin film within the slit.

[0006] However, forming an additional thin film increases the number of steps, which may increase the manufacturing cost of the piezoelectric element.

[0007] In view of the above, an object of the present invention is to provide a piezoelectric element, a microphone, and a method for manufacturing a piezoelectric element that can reduce an increase in the number of steps. [Means for solving the problem]

[0008] In order to achieve the above object, the invention described in claim 1 provides a piezoelectric element having a vibration part (20) arranged on a support (10), comprising a piezoelectric film (40) arranged on the support, an electrode film (50) laminated on the piezoelectric film, through electrodes (61b, 62b) formed inside holes (61a, 62a) penetrating the piezoelectric film, and an interlayer insulating film (82) formed on the wall surfaces of the holes and on the top of the piezoelectric film to insulate the piezoelectric film from the through electrodes, wherein the vibration part includes the piezoelectric film and the electrode film, and has a support region (21a) supported by the support and a floating region (21b) floating above the support, and the floating region has a plurality of vibration regions (22a to 22d) partitioned by slits (30), and an additional thin film (81) made of the same material as the interlayer insulating film is arranged in the slit.

[0009] According to this, since the additional thin film and the interlayer insulating film are made of the same material, they can be formed in the same process, and an increase in the number of steps in manufacturing the piezoelectric element can be reduced.

[0010] Also, claims 10In the invention described above, a method for manufacturing a piezoelectric element having a vibration part (20) arranged on a support (10) includes forming a piezoelectric film (40) on the support, forming an electrode film (50) laminated on the piezoelectric film, forming holes (61a, 62a) penetrating the piezoelectric film, forming through electrodes (61b, 62b) inside the holes, forming an interlayer insulating film (82) on the wall surfaces of the holes and on the top of the piezoelectric film to insulate the piezoelectric film from the through electrodes, forming slits (30) in a floating region that includes the piezoelectric film and the electrode film and floats above the support to divide the piezoelectric film and the electrode film into a plurality of vibration regions (22a to 22d), and forming an additional thin film (81) made of the same material as the interlayer insulating film in the slit, and the forming of the interlayer insulating film and the forming of the additional thin film are performed simultaneously.

[0011] According to this method, the additional thin film and the interlayer insulating film are simultaneously formed from the same material, so that an increase in the number of steps can be reduced.

[0012] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view of a piezoelectric element according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] FIG. 2 is a plan view of the vicinity of the first and second holes. [Figure 4A] 5A to 5C are cross-sectional views showing a manufacturing process of a piezoelectric element. [Figure 4B] 4B is a cross-sectional view showing a manufacturing process of the piezoelectric element subsequent to FIG. 4A. [Figure 4C] 4C is a cross-sectional view showing the manufacturing process of the piezoelectric element subsequent to FIG. 4B. [Figure 4D] 4D is a cross-sectional view showing a manufacturing process of the piezoelectric element subsequent to FIG. 4C. [Figure 4E] 4D. FIG. 4E is a cross-sectional view showing the manufacturing process of the piezoelectric element subsequent to FIG. 4D. [Figure 4F] 4F is a cross-sectional view showing a manufacturing process of the piezoelectric element subsequent to FIG. 4E. [Figure 4G] FIG. 4C is a cross-sectional view showing the manufacturing process of the piezoelectric element subsequent to FIG. 4F. [Figure 4H] 4G. FIG. 4G is a cross-sectional view showing the manufacturing process of the piezoelectric element. [Figure 5] FIG. 10 is a cross-sectional view of a comparative example. [Figure 6] FIG. 6 is a cross-sectional view of a piezoelectric element according to a second embodiment. [Figure 7A] 5A to 5C are cross-sectional views showing a manufacturing process of a piezoelectric element. [Figure 7B] 7B is a cross-sectional view showing the manufacturing process of the piezoelectric element subsequent to FIG. 7A. [Figure 8A] 5A to 5C are cross-sectional views showing a manufacturing process of a piezoelectric element. [Figure 8B] 8B is a cross-sectional view showing the manufacturing process of the piezoelectric element subsequent to FIG. 8A. [Figure 9A] 5A to 5C are cross-sectional views showing a manufacturing process of a piezoelectric element. [Figure 9B] 9B is a cross-sectional view showing the manufacturing process of the piezoelectric element subsequent to FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, parts that are identical or equivalent to each other will be denoted by the same reference numerals.

[0015] (First embodiment) A first embodiment will be described. The piezoelectric element of this embodiment is suitable for use in a piezoelectric microphone mounted on a smartphone, an AI (artificial intelligence) speaker, etc. The piezoelectric element of this embodiment is also suitable for use in an ultrasonic sensor, etc.

[0016] 1 and 2, the piezoelectric element includes a support 10 and a vibrating part 20 disposed on the support 10, and has a rectangular planar shape. The support 10 includes a support substrate 11 having one surface 11a, and an insulating film 12 formed on the one surface 11a of the support substrate 11. 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.

[0017] A recess 10a is formed in the support 10 to float the inner edge side of the vibration section 20. Therefore, the vibration section 20 has a configuration including a support region 21a arranged on the support 10 and a floating region 21b that is connected to the support region 21a and floats above the recess 10a. In this embodiment, the opening end of the recess 10a on the vibration section 20 side has a rectangular shape in plan view. Therefore, the entire floating region 21b has a rectangular shape in plan view.

[0018] Openings 12a and 20a are formed in the outer edge portions of the insulating film 12 and the vibrating portion 20 to expose the outer edge portions of the support substrate 11. The openings 12a and 20a facilitate the dicing process when manufacturing the piezoelectric element, and are not necessarily required to be formed.

[0019] The floating region 21b is formed with slits 30 that penetrate the floating region 21b in the thickness direction. The slits 30 are formed so as to divide the floating region 21b into four parts. Specifically, two slits 30 are formed so as to pass through the center of the floating region 21b and extend toward opposite corners of the floating region 21b. In other words, the slits 30 extend from each corner of the floating region 21b, which has a rectangular planar shape, toward the center, and the slits 30 are formed so as to intersect at the center. As a result, the floating region 21b is divided into first to fourth vibration regions 22a to 22d, each of which has a substantially triangular planar shape.

[0020] Although the slits 30 in this embodiment extend to the support region 21a, they may be formed so as to terminate within the floating region 21b. Alternatively, the slits 30 may be formed so as to terminate at the boundary between the floating region 21b and the support region 21a.

[0021] The first to fourth vibrating regions 22a to 22d are configured as described above, and are configured as cantilevers in which the end on the support region 21a side is a fixed end and the tip end on the opposite side to the support region 21a is a free end.

[0022] The vibration section 20 is configured to include a piezoelectric film 40 and an electrode film 50 connected to the piezoelectric film 40. Specifically, the piezoelectric film 40 includes a lower-layer piezoelectric film 41 and an upper-layer piezoelectric film 42 laminated on the lower-layer piezoelectric film 41. The lower-layer piezoelectric film 41 and the upper-layer piezoelectric film 42 are made of lead-free piezoelectric ceramics such as scandium aluminum nitride (ScAlN) and aluminum nitride (AlN). The lower-layer piezoelectric film 41 and the upper-layer piezoelectric film 42 are made of lead zirconate titanate (PZT) or the like. Although FIG. 1 is not a cross-sectional view, the upper-layer piezoelectric film 42 and the like are hatched to facilitate understanding.

[0023] The electrode film 50 is formed on each of the vibration regions 22a to 22d so as to be connected to the piezoelectric film 40, and is made of molybdenum (Mo). However, the electrode film 50 may be made of a metal material containing, as a main component, any one of titanium (Ti), platinum (Pt), aluminum (Al), ruthenium (Ru), etc., in addition to molybdenum.

[0024] In this embodiment, the electrode films 50 include a lower electrode film 51 formed below the lower piezoelectric film 41, an intermediate electrode film 52 formed between the lower piezoelectric film 41 and the upper piezoelectric film 42, and an upper electrode film 53 formed above the upper piezoelectric film 42. The lower electrode film 51 and the intermediate electrode film 52 are arranged to face each other with the lower piezoelectric film 41 in between. The intermediate electrode film 52 and the upper electrode film 53 are arranged to face each other with the upper piezoelectric film 42 in between.

[0025] The electrode films 50 of the first to fourth vibrating regions 22a to 22d are electrically connected in series by the wiring portion 60. Specifically, the lower-layer electrode films 51, the intermediate electrode films 52, and the upper-layer electrode films 53 formed in the vibrating regions 22a to 22d are connected in parallel, and the vibrating regions 22a to 22d are connected in series.

[0026] The wiring section 60 includes a first electrode section 61 connected to the lower-layer electrode film 51, a second electrode section 62 connected to the middle-layer electrode film 52, and a wiring film 63 connecting the first electrode section 61 and the second electrode section 62. The wiring section 60 also includes an electrode section (not shown) connected to the upper-layer electrode film 53, and the first electrode section 61 and the second electrode section 62 are also connected to this electrode section (not shown) by the wiring film 63.

[0027] In the support region 21a, a first hole portion 61a is formed that penetrates the lower-layer piezoelectric film 41 and the upper-layer piezoelectric film 42 to expose the lower-layer electrode film 51, and the first electrode portion 61 has a first through electrode 61b arranged in the first hole portion 61a so as to be electrically connected to the lower-layer electrode film 51. In addition, in the support region 21a, a second hole portion 62a is formed that penetrates the upper-layer piezoelectric film 42 to expose the middle-layer electrode film 52, and the second electrode portion 62 has a second through electrode 62b arranged in the second hole portion 62a so as to be electrically connected to the middle-layer electrode film 52.

[0028] As will be described later, an interlayer insulating film 82 is formed on the wall surfaces of the first hole portion 61a, the wall surfaces of the second hole portion 62a, and the upper surface of the upper-layer piezoelectric film 42. The first through electrode 61b and the second through electrode 62b are disposed inside the first hole portion 61a and the second hole portion 62a, respectively, so as to be insulated from the piezoelectric film 40 by the interlayer insulating film 82. The wiring film 63 is disposed on the upper surface of the interlayer insulating film 82 and is electrically connected to the first through electrode 61b and the second through electrode 62b at the upper portions of the first hole portion 61a and the second hole portion 62a. Note that FIG. 1 illustrates only a portion of the wiring film 63 that connects the first through electrode 61a and the second through electrode 62b and a pad portion that is connected to an external circuit.

[0029] The vibration section 20 has a buffer layer 70 on the support 10 side, on which a lower piezoelectric film 41 and a lower electrode film 51 are arranged. The buffer layer 70 is made of, for example, aluminum nitride (AlN). The buffer layer 70 is formed over the entire portion that will become the floating region 21b. Note that the buffer layer 70 and the lower electrode film 51 are not formed up to the outer edge of the insulating layer 12. Therefore, the outer edge portion of the lower piezoelectric film 41 is disposed directly on the insulating film 12.

[0030] In the piezoelectric element of this embodiment, an additional thin film 81 is provided so as to cover a part of the slit 30 formed in the floating region 21b. Specifically, the additional thin film 81 is arranged in the part of the slit 30 opposite the support region 21a, that is, in the part that defines the free end sides of the first to fourth vibrating regions 22a to 22d. Therefore, the vibrating regions 22a to 22d are connected by the additional thin film 81 at the free end side. Note that, although FIG. 2 shows a diagram in which the additional thin film 81 is arranged so as to fill the slit 30, the additional thin film 81 does not have to be arranged so as to fill the slit 30.

[0031] The additional thin film 81 is intended to suppress warping of the first to fourth vibrating regions 22a to 22d after the recesses 10a are formed. The additional thin film 81 is preferably made of a material with a low Young's modulus so that it is less likely to affect the vibration of each of the vibrating regions 22a to 22d. The thickness of the additional thin film 81 is, for example, 0.5 μm to 3 μm.

[0032] An interlayer insulating film 82 is formed on the wall surfaces of the first hole portion 61a and the second hole portion 62a. The interlayer insulating film 82 is intended to suppress leakage between the electrodes. The interlayer insulating film 82 is also formed on the upper surface of the upper-layer piezoelectric film 42, and the first electrode portion 61 and the second electrode portion 62 are connected via a wiring film 63 formed on the upper surface of the interlayer insulating film 82. The interlayer insulating film 82 is made of the same material as the additional thin film 81. Specifically, the additional thin film 81 and the interlayer insulating film 82 are made of a photosensitive resin such as polyimide or polybenzoxazole (PBO).

[0033] In the center of the piezoelectric element, an opening 82a is formed in the interlayer insulating film 82, thereby exposing the upper electrode film 53 in the floating region 21b from the interlayer insulating film 82. The opening 82a corresponds to a first opening. In addition, in the outer periphery of the piezoelectric element, openings 82b are formed in the interlayer insulating film 82, thereby exposing the upper piezoelectric film 42 in the support region 21a from the interlayer insulating film 82. The openings 82b correspond to a second opening. The openings 82b are linear slits, and four openings 82b are formed so as to be parallel to the four sides of the top surface of the piezoelectric element. The openings 82b may have other shapes.

[0034] The volume of the portion of the interlayer insulating film 82 formed between the first hole 61a and the opening 82a is equal to the volume of the portion formed on the opposite side of the first hole 61a from the opening 82a. Specifically, as shown in Figures 2 and 3, the region of the interlayer insulating film 82 between the first hole 61a and the opening 82a is defined as an inner region 82c, and the region between the first hole 61a and the opening 82b is defined as an outer region 82d, and the volumes of the inner region 82c and the outer region 82d are equal. Note that the wiring film 63 is not shown in Figure 3.

[0035] 2 and 3, the region of the interlayer insulating film 82 between the second hole 62a and the opening 82a is defined as an inner region 82e, and the region of the interlayer insulating film 82 between the second hole 62a and the opening 82a is defined as an outer region 82f, and the volumes of the inner region 82e and the outer region 82f are made equal.

[0036] The above is the configuration of the piezoelectric element in this embodiment. In such a piezoelectric element, when pressure such as sound pressure is applied to each of the vibration regions 22a to 22d, the vibration regions 22a to 22d vibrate. Then, for example, when the free end side of each of the vibration regions 22a to 22d is displaced upward, tensile stress is generated in the lower-layer piezoelectric film 41 and compressive stress is generated in the upper-layer piezoelectric film 42. Therefore, pressure such as sound pressure is detected by extracting charge from the pad portion of the wiring portion 60. At this time, in this embodiment, the opening area of ​​the slit 30 is reduced by the additional thin film 81. This makes it difficult for pressure to escape from the slit 30, and the detection band can be widened.

[0037] Next, a method for manufacturing the piezoelectric element will be described with reference to Figures 4A to 4H. In this embodiment, an example in which a piezoelectric element is manufactured using a wafer-shaped support 10 will be described, but piezoelectric elements may also be manufactured using support 10 that has been divided into chip units in advance.

[0038] First, as shown in Fig. 4A, a support 10 is prepared in which an insulating film 12 is disposed on a support substrate 11. Note that the support 10 in Fig. 4A is actually in the form of a wafer in which a plurality of element configuration regions are integrated via dicing lines.

[0039] 4B, a buffer layer 70 and a lower electrode film 51 are sequentially formed on the support 10 and patterned into a predetermined shape using a mask (not shown). The buffer layer 70 and the lower electrode film 51 are patterned so as to be disposed in a portion that will become the floating region 21b. The buffer layer 70 and the lower electrode film 51 are also patterned so as to include a portion connected to the first through-electrode 61b and a portion facing the second through-electrode 62b in the stacking direction of the support 10 and the vibration section 20.

[0040] The buffer layer 70 and the lower electrode film 51 are formed by a general sputtering method, a CVD (Chemical Vapor Deposition) method, etc. The lower piezoelectric film 41, the intermediate electrode film 52, the upper piezoelectric film 42, and the upper electrode film 53, which will be described later, are also formed by a general sputtering method, a CVD method, etc.

[0041] Next, as shown in Fig. 4C, a lower-layer piezoelectric film 41 and an intermediate electrode film 52 are formed. Then, as shown in Fig. 4D, an upper-layer piezoelectric film 42 is formed to form the piezoelectric film 40. Furthermore, an upper-layer electrode film 53 is formed and patterned into a predetermined shape using a mask (not shown), thereby forming the electrode film 50.

[0042] 4E, by etching using a mask (not shown), a first hole 61a exposing the lower electrode film 51, a second hole 62a exposing the intermediate electrode film 52, and a slit 30 exposing the insulating film 12 are formed. In addition, the piezoelectric film 40 located on the dicing line is removed to form an opening 20a, and the insulating film 12 is removed to form an opening 12a.

[0043] Next, as shown in FIG. 4F, photosensitive resin 80 is applied to the entire wafer so as to cover support 10, piezoelectric film 40, electrode film 50, and buffer layer 70. Next, as shown in FIG. 4G, the photosensitive resin 80 is exposed to light using a mask (not shown), thereby removing the photosensitive resin 80 from portions corresponding to openings 82a, 82b, first hole 61a, and second hole 62a, thereby forming additional thin film 81 and interlayer insulating film 82. At this time, openings 82a and 82b are formed so that inner region 82c and outer region 82d have the same volume, and so that inner region 82e and outer region 82f have the same volume.

[0044] 4H, a metal film is formed so as to fill the first hole 61a and the second hole 62a, thereby forming the first through electrode 61b and the second through electrode 62b. Then, the metal film formed on the interlayer insulating film 82 is patterned to form the wiring film 63. In this way, the wiring section 60 is formed.

[0045] Thereafter, a mask (not shown) is placed as appropriate and etching is performed to form recesses 10a. The substrate is then divided into chips along dicing lines. This completes the manufacture of the piezoelectric element described above, in which the vibration portion 20 is disposed on the support 10.

[0046] According to the present embodiment described above, the additional thin film 81 and the interlayer insulating film 82 are made of the same material. Therefore, as described above, it is possible to form the additional thin film 81 and the interlayer insulating film 82 in the same process, thereby reducing an increase in the number of steps in manufacturing the piezoelectric element.

[0047] Furthermore, according to the above embodiment, the following effects can be obtained.

[0048] (1) The portions of the interlayer insulating film 82 formed between the first and second holes 61a, 62a and the opening 82a have the same volume as the portions formed on the opposite side of the opening 82a from the first and second holes 61a, 62a. If the interlayer insulating film 82 is made of a photosensitive resin, the interlayer insulating film 82 shrinks when hardened. Therefore, if the volume of the interlayer insulating film 82 differs significantly between the first and second holes 61a, 62a, the interlayer insulating film 82 within the first and second holes 61a, 62a will be asymmetric, as shown in FIG. 5. On the other hand, in a piezoelectric microphone, it is necessary to remove the interlayer insulating film 82 from the vibration region, and the formation of the opening 82a results in a significant difference in volume between the interlayer insulating film 82 on both sides of the first and second holes 61a, 62a. As a result, insulation performance decreases on one side where the interlayer insulating film 82 is thinner, and coverage decreases when forming wiring metal due to the overhang structure on the other side where the interlayer insulating film 82 is thicker, which may result in disconnection. In response to this, by making the volume of the interlayer insulating film 82 equal on both sides of the first and second holes 61a, 62a as described above, the symmetry of the interlayer insulating film 82 inside the first and second holes 61a, 62a can be improved, and the deterioration of insulation performance and disconnection can be suppressed.

[0049] (2) An opening 82b exposing the piezoelectric film 40 is formed in a portion of the interlayer insulating film 82 that is formed on the opposite side of the opening 82a with respect to the first and second hole portions 61a and 62a. By forming the opening 82b in this manner, the volumes of the inner regions 82c and 82e and the outer regions 82d and 82f can be adjusted, and a decrease in insulation properties and disconnection can be suppressed.

[0050] (3) In the interlayer insulating film 82, the inner region 82c and the outer region 82d have the same volume, and the inner region 82e and the outer region 82f have the same volume, which improves the symmetry of the interlayer insulating film 82 in the first and second holes 61a and 62a, and can prevent deterioration of insulation properties and disconnections.

[0051] (4) The additional thin film 81 and the interlayer insulating film 82 are made of a photosensitive resin such as polyimide or PBO. In a piezoelectric microphone, the electrode thickness is as thin as several tens of nanometers. Therefore, if TEOS (tetraethoxysilane) is used as the interlayer insulating film 82, for example, there is a risk that the electrode film 50 will be damaged when the interlayer insulating film 82 is patterned by etching. In contrast, by using a photosensitive resin as the additional thin film 81 and the interlayer insulating film 82, the additional thin film 81 and the interlayer insulating film 82 can be patterned by photolithography, and damage to the electrode film 50 can be suppressed.

[0052] (5) The piezoelectric element has a bimorph structure in which a lower-layer electrode film 51, a lower-layer piezoelectric film 41, a middle-layer electrode film 52, an upper-layer piezoelectric film 42, and an upper-layer electrode film 53 are laminated in this order. In a piezoelectric element having such a configuration, the interlayer insulating film 82 can suppress leakage at the interface between the lower-layer piezoelectric film 41 and the upper-layer piezoelectric film 42.

[0053] (6) By using the piezoelectric element of this embodiment in a microphone, low It can be made noise-free and broadband.

[0054] (Second embodiment) The second embodiment will be described. This embodiment is different from the first embodiment in the configuration of the interlayer insulating film 82, but is otherwise similar to the first embodiment, so only the differences from the first embodiment will be described.

[0055] In this embodiment, the film thickness of the interlayer insulating film 82 is different between a portion formed between the first hole 61a and the opening 82a and a portion formed on the opposite side of the first hole 61a from the opening 82a. Specifically, as shown in Fig. 6, the region of the interlayer insulating film 82 between the first hole 61a and the outer edge of the interlayer insulating film 82 is defined as an outer region 82g, and a part of the outer region 82g is thinned so that the volumes of the inner region 82c and the outer region 82g are equal.

[0056] 6, the region of the interlayer insulating film 82 between the second hole 62a and the opening 82a has a different film thickness from the region of the interlayer insulating film 82 formed on the opposite side of the opening 82a with respect to the second hole 62a. Specifically, as shown in FIG. 6, the region of the interlayer insulating film 82 between the second hole 62a and the outer edge of the interlayer insulating film 82 is defined as an outer region 82h, and part of the outer region 82h is thinned so that the volumes of the inner region 82e and the outer region 82h are equal.

[0057] In this embodiment, after the step shown in Fig. 4F, as shown in Fig. 7A, the photosensitive resin 80 is exposed to a small amount of light using a mask 91 that exposes the portions to be thinned in the outer regions 82g and 82h. Then, as shown in Fig. 7B, the photosensitive resin 80 is exposed to a larger amount of light than in the step shown in Fig. 7A using a mask 92 that exposes portions corresponding to the openings 12a and 20a, the first hole 61a, the second hole 62a, and the opening 82a. This forms the interlayer insulating film 82 in which portions of the outer regions 82g and 82h have been thinned.

[0058] This embodiment has the same configuration and operation as the first embodiment, and can therefore obtain the same effects as the first embodiment.

[0059] Furthermore, according to the above embodiment, the following effects can be obtained.

[0060] (1) The thickness of the interlayer insulating film 82 differs between the inner regions 82c and 82d and the outer regions 82g and 82h. By varying the film thickness depending on the location, it is possible to adjust the volume without exposing the upper piezoelectric film 43, and the area protected by the interlayer insulating film 82 is widened, thereby suppressing damage to the piezoelectric element.

[0061] (Other embodiments) The present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the claims. It goes without saying that, in each of the above embodiments, the elements constituting the embodiments are not necessarily essential unless expressly stated as essential or clearly considered essential in principle. In each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of components of the embodiments are mentioned, they are not limited to the specific numbers unless expressly stated as essential or clearly limited to a specific number in principle. In each of the above embodiments, when the shape, positional relationship, etc. of components are mentioned, they are not limited to the shape, positional relationship, etc. unless expressly stated or clearly limited to a specific shape, positional relationship, etc. in principle.

[0062] For example, in the first embodiment, not only in a configuration in which the inner regions 82c, 82e and the outer regions 82d, 82f have completely equal volumes, but also in a configuration in which they are approximately equal, it is possible to improve the symmetry of the interlayer insulating film 82 in the first and second hole portions 61a, 62a and suppress deterioration of insulation properties, etc.

[0063] Furthermore, in the second embodiment, not only in a configuration in which the inner regions 82c, 82e and the outer regions 82g, 82h have completely equal volumes, but also in a configuration in which they are approximately equal, it is possible to improve the symmetry of the interlayer insulating film 82 in the first and second hole portions 61a, 62a and suppress deterioration of insulation properties, etc.

[0064] In addition, in the second embodiment, depending on the locations of the first and second hole portions 61a, 62a and the size of the opening 82a, the volumes of the inner regions 82c, 82e and the outer regions 82g, 82h may be made equal by thinning portions of the inner regions 82c, 82e.

[0065] In the second embodiment, the portions of photosensitive resin 80 corresponding to openings 12a and 20a may be exposed twice. That is, after the step shown in Fig. 4F, photosensitive resin 80 is exposed using a mask 91 that exposes the portions corresponding to openings 12a and 20a and the thinned portions of outer regions 82g and 82h, and then photosensitive resin 80 is exposed using a mask 92 as shown in Fig. 7B.

[0066] In the second embodiment, the photosensitive resin 80 may be exposed to light to form the additional thin film 81 and the interlayer insulating film 82, as shown in FIGS. 8A and 8B. That is, after the step shown in FIG. 4F , the photosensitive resin 80 is exposed to a low amount of light using a mask 91 that exposes the portions corresponding to the openings 12a and 20a, the first hole 61a, the second hole 62a, and the opening 82a, as well as the thinned portions of the outer regions 82g and 82h. Next, the photosensitive resin 80 is exposed to a low or medium amount of light, similar to the step shown in FIG. 8A, using a mask 92 that exposes the portions corresponding to the openings 12a and 20a, the first hole 61a, the second hole 62a, and the opening 82a. Considering misalignment, the method shown in FIGS. 7A and 7B is preferable to this method.

[0067] 9A and 9B, the photosensitive resin 80 may be exposed to light to form the additional thin film 81 and the interlayer insulating film 82. That is, after the step shown in FIG. 4F, the photosensitive resin 80 is exposed to light using a mask 91 that exposes the portions corresponding to the openings 12a, 20a, and 82a and the thinned portions of the outer regions 82g and 82h. Next, the photosensitive resin 80 is exposed to light using a mask 92 that exposes the portions corresponding to the openings 12a, 20a, the first hole 61a, the second hole 62a, and the opening 82a. [Explanation of symbols]

[0068] 10 Support 20 Vibration unit 30 slits 40 Piezoelectric film 50 Electrode membrane 81 Additional Thin Film 82 Interlayer insulating film

Claims

1. A piezoelectric element in which a vibration part (20) is disposed on a support (10), a piezoelectric film (40) disposed on the support; an electrode film (50) laminated on the piezoelectric film; through electrodes (61b, 62b) formed inside holes (61a, 62a) penetrating the piezoelectric film; an interlayer insulating film (82) formed on the wall surface of the hole and on the upper portion of the piezoelectric film, for insulating the piezoelectric film from the through electrode; the vibration section includes the piezoelectric film and the electrode film, and has a support region (21a) supported by the support body and a floating region (21b) floating above the support body; The floating region has a plurality of vibration regions (22a to 22d) divided by slits (30), A piezoelectric element in which an additional thin film (81) made of the same material as the interlayer insulating film is disposed in the slit.

2. A first opening (82a) exposing the vibration region is formed in the interlayer insulating film, 2. The piezoelectric element according to claim 1, wherein a second opening (82b) exposing the piezoelectric film is formed in a portion of the interlayer insulating film formed on the opposite side of the hole from the first opening.

3. 3. The piezoelectric element according to claim 2, wherein the additional thin film and the interlayer insulating film are made of a photosensitive resin.

4. 4. The piezoelectric element according to claim 3, wherein the photosensitive resin is polyimide or polybenzoxazole.

5. 2. The piezoelectric element according to claim 1, wherein the additional thin film and the interlayer insulating film are made of a photosensitive resin.

6. 6. The piezoelectric element according to claim 5, wherein the photosensitive resin is polyimide or polybenzoxazole.

7. The piezoelectric film has a lower piezoelectric film (41) and an upper piezoelectric film (42), 7. A piezoelectric element as described in any one of claims 1 to 6, wherein the electrode film comprises a lower electrode film (51) formed below the lower piezoelectric film, an intermediate electrode film (52) formed between the lower piezoelectric film and the upper piezoelectric film, and an upper electrode film (53) formed above the upper piezoelectric film.

8. A microphone comprising the piezoelectric element according to any one of claims 1 to 6.

9. A microphone comprising the piezoelectric element according to claim 7.

10. A method for manufacturing a piezoelectric element in which a vibration part (20) is disposed on a support (10), comprising the steps of: forming a piezoelectric film (40) on the support; forming an electrode film (50) laminated on the piezoelectric film; forming holes (61a, 62a) penetrating the piezoelectric film; forming a through electrode (61b, 62b) inside the hole; forming an interlayer insulating film (82) on the wall surface of the hole and on the upper portion of the piezoelectric film to insulate the piezoelectric film from the through electrode; forming slits (30) in a floating region that includes the piezoelectric film and the electrode film and is floating above the support, and dividing the piezoelectric film and the electrode film into a plurality of vibration regions (22a to 22d); forming an additional thin film (81) made of the same material as the interlayer insulating film in the slit; A method for manufacturing a piezoelectric element, wherein the formation of the interlayer insulating film and the formation of the additional thin film are carried out simultaneously.

11. forming a first opening (82a) in the interlayer insulating film to expose the vibration region; and forming a second opening (82b) exposing the piezoelectric film in a portion of the interlayer insulating film formed on the opposite side of the hole from the first opening.

12. 12. The method for manufacturing a piezoelectric element according to claim 10, wherein the additional thin film and the interlayer insulating film are made of a photosensitive resin.

13. The method for manufacturing a piezoelectric element according to claim 12, wherein the photosensitive resin is polyimide or polybenzoxazole.

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