JP2023155792A - Piezoelectric element, microphone and method of manufacturing piezoelectric element - Google Patents

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

The present invention relates to a piezoelectric element, a microphone, and a method for manufacturing a piezoelectric element.

A piezoelectric MEMS (Micro Electro Mechanical Systems) microphone is composed of a piezoelectric element having a laminated structure of electrodes and a piezoelectric film. In the manufacturing process of a piezoelectric element, a lower electrode is formed on the entire upper surface of a substrate, a portion is removed by patterning, and then a piezoelectric film is formed on the upper surface of the lower electrode. Then, an upper electrode is formed on the upper surface of this piezoelectric film. A via that exposes the lower electrode is formed in the piezoelectric film, and the potential of the lower electrode is taken out by a wiring formed within the via. Further, by forming an opening in the substrate and forming a slit in the laminated structure of the electrode and the piezoelectric film, this laminated structure is supported in a cantilever manner at the open end of the substrate, forming a vibration region.

The piezoelectric film formed in the area where the electrode has been removed has poor crystallinity, and there is a risk that cracks will occur due to stress concentration at the end of the electrode, resulting in a decrease in resistance value. If leakage occurs between the electrodes through the portion where the resistance value has decreased, dielectric loss increases and microphone noise increases, so it is necessary to block the leakage. An interlayer insulating film is usually used for this purpose (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 10-74836

In such microphones, the vibration region vibrates when pressure such as sound pressure is applied, and the charge generated in the piezoelectric film is output as a detection signal, but the vibration region is deformed due to residual stress generated during manufacturing. There is a risk that the slit will widen and the pressure will escape, narrowing the detection band. Regarding this, the present inventors have proposed in Japanese Patent Application No. 2021-152427 a piezoelectric element that suppresses the expansion of the slit by forming an additional thin film inside the slit.

However, since forming the additional thin film increases the number of steps, there is a risk that the manufacturing cost of the piezoelectric element will increase.

In view of the above points, 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 the increase in the number of steps.

In order to achieve the above object, the invention according to claim 1 provides a piezoelectric element in which a vibrating part (20) is disposed on a support (10), and a piezoelectric film (40) disposed on the support. , an electrode film (50) laminated on the piezoelectric film, through electrodes (61b, 62b) formed inside the holes (61a, 62a) penetrating the piezoelectric film, and the wall surface of the hole and the upper part of the piezoelectric film. The vibrating section includes an interlayer insulating film (82) that is formed on the substrate and insulates the piezoelectric film and the through electrode, and the vibrating section includes a support region (21a) that is supported by a support body and includes a piezoelectric film and an electrode film; The floating region has a floating region (21b) floating from the body, and the floating region has a plurality of vibration regions (22a to 22d) partitioned by slits (30). An additional thin film (81) composed of material is arranged.

According to this, since the additional thin film and the interlayer insulating film are made of the same material, it is possible to form them in the same process, and it is possible to reduce the increase in man-hours in manufacturing the piezoelectric element. .

Further, the invention according to claim 11 is a method for manufacturing a piezoelectric element in which a vibrating part (20) is arranged on a support (10), comprising: 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, and forming through electrodes (61b, 62b) inside the holes. In addition, an interlayer insulating film (82) is formed on the wall surface of the hole and on the top of the piezoelectric film to insulate the piezoelectric film and the through electrode, and a floating region floating from the support including the piezoelectric film and the electrode film is formed. A slit (30) is formed to divide the piezoelectric film and the electrode film into a plurality of vibration regions (22a to 22d), and an additional thin film (81) made of the same material as the interlayer insulating film is formed in the slit. forming the interlayer insulating film and forming the additional thin film are performed simultaneously.

According to this, since the additional thin film and the interlayer insulating film are simultaneously formed of the same material, an increase in the number of steps can be reduced.

Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence between the component etc. and specific components etc. described in the embodiments to be described later.

FIG. 2 is a plan view of a piezoelectric element according to a first embodiment. 2 is a sectional view taken along line II-II in FIG. 1. FIG. FIG. 3 is a plan view of the vicinity of the first and second holes. FIG. 3 is a cross-sectional view showing a manufacturing process of a piezoelectric element. FIG. 4A is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4A. FIG. 4B is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4B. FIG. 4C is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4C. FIG. 4D is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4D. FIG. 4E is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4E. FIG. 4F is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4F. FIG. 4G is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 4G. FIG. 3 is a cross-sectional view of a comparative example. FIG. 3 is a cross-sectional view of a piezoelectric element according to a second embodiment. FIG. 3 is a cross-sectional view showing a manufacturing process of a piezoelectric element. FIG. 7A is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 7A. FIG. 3 is a cross-sectional view showing a manufacturing process of a piezoelectric element. FIG. 8A is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 8A. FIG. 3 is a cross-sectional view showing a manufacturing process of a piezoelectric element. FIG. 9A is a cross-sectional view showing the manufacturing process of the piezoelectric element following FIG. 9A.

Embodiments of the present invention will be described below based on the drawings. Note that in each of the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment will be described. The piezoelectric element of this embodiment is suitable for use in a piezoelectric microphone installed in a smartphone, an AI (artificial intelligence) speaker, or the like. Further, the piezoelectric element of this embodiment is suitable for use in an ultrasonic sensor or the like.

As shown in FIGS. 1 and 2, the piezoelectric element includes a support 10 and a vibrating section 20 disposed on the support 10, and has a rectangular planar shape. The support body 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. Note that the support substrate 11 is made of, for example, a silicon substrate, and the insulating film 12 is made of an oxide film or the like.

A recess 10a is formed in the support 10 to float the inner edge of the vibrating part 20. Therefore, the vibrating section 20 has a support region 21a disposed on the support body 10, and a floating region 21b that is connected to the support region 21a and floats on the recess 10a. In the recess 10a of this embodiment, the opening end on the vibrating section 20 side has a rectangular planar shape. Therefore, the entire floating region 21b has a planar rectangular shape.

Openings 12 a and 20 a are formed at the outer edges of the insulating film 12 and the vibrating section 20 to expose the outer edges of the support substrate 11 . The openings 12a and 20a facilitate the dicing process when manufacturing the piezoelectric element, and do not necessarily need to be formed.

A slit 30 is formed in the floating region 21b, passing through the floating region 21b in the thickness direction. The slit 30 is formed to divide the floating region 21b into four. Specifically, two slits 30 are formed so as to pass through the center of the floating region 21b and extend toward opposing 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 are formed so that the slits 30 intersect at the center. As a result, the floating region 21b is divided into first to fourth vibration regions 22a to 22d each having a substantially triangular planar shape.

Although the slit 30 in this embodiment extends to the support region 21a, it may be formed to terminate within the floating region 21b. Further, the slit 30 may be formed to terminate at the boundary between the floating region 21b and the support region 21a.

The first to fourth vibration regions 22a to 22d have the above-described configuration, so that the end on the side of the support region 21a is a fixed end, and the tip on the side opposite to the support region 21a is a cantilever with a free end. It is said that

The vibrating 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 piezoelectric film 41 and an upper piezoelectric film 42 stacked on the lower piezoelectric film 41. Note that the lower layer piezoelectric film 41 and the upper layer piezoelectric film 42 are constructed using lead-free piezoelectric ceramics such as scandium aluminum nitride (ScAlN) and aluminum nitride (AlN). Further, the lower piezoelectric film 41 and the upper piezoelectric film 42 are constructed using lead zirconate titanate (PZT) or the like. Although FIG. 1 is not a cross-sectional view, the upper piezoelectric film 42 and the like are hatched for ease of understanding.

The electrode film 50 is formed in 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 is made of a metal material whose main component is any one of titanium (Ti), platinum (Pt), aluminum (Al), ruthenium (Ru), etc. in addition to molybdenum. It's okay.

In this embodiment, the electrode film 50 includes 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, An upper layer electrode film 53 is formed above the upper layer piezoelectric film 42. Note that 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.

The electrode films 50 of the first to fourth vibration regions 22a to 22d are electrically connected in series by a wiring section 60. Specifically, each lower layer electrode film 51, each intermediate electrode film 52, and each upper layer electrode film 53 formed in each vibration region 22a to 22d are connected in parallel, while each vibration region 22a to 22d is connected in series. It is connected.

The wiring section 60 includes a first electrode section 61 connected to the lower electrode film 51, a second electrode section 62 connected to the middle electrode film 52, and a wiring connecting the first electrode section 61 and the second electrode section 62. A membrane 63 is provided. Further, the wiring section 60 includes an electrode section (not shown) connected to the upper electrode film 53, and the first electrode section 61 and the second electrode section 62 are also connected to this electrode section (not shown) through the wiring film 63. has been done.

A first hole 61a is formed in the support region 21a to penetrate the lower piezoelectric film 41 and the upper piezoelectric film 42 and expose the lower electrode film 51. The first electrode part 61 is electrically connected to the lower electrode film 51. The first through electrode 61b is disposed in the first hole 61a so as to be connected to the first through electrode 61b. Further, a second hole 62a is formed in the support region 21a to penetrate the upper piezoelectric film 42 and expose the middle electrode film 52, and the second electrode part 62 is electrically connected to the middle electrode film 52. A second through electrode 62b is provided in the second hole 62a so that the second through electrode 62b is arranged in the second hole 62a.

As will be described later, an interlayer insulating film 82 is formed on the wall surface of the first hole 61a, the wall surface of the second hole 62a, and the upper surface of the upper layer piezoelectric film 42. The first through electrode 61b and the second through electrode 62b are arranged inside the first hole 61a and the second hole 62a so as to be insulated from the piezoelectric film 40 by the interlayer insulating film 82, respectively. 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 above the first hole 61a and the second hole 62a. There is. Note that, in FIG. 1, 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 are illustrated.

The vibrating section 20 has a buffer layer 70 on the support body 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 placed directly on the insulating film 12.

In the piezoelectric element of this embodiment, an additional thin film 81 is provided to cover a part of the slit 30 formed in the floating region 21b. Specifically, the additional thin film 81 is arranged in a portion of the slit 30 opposite to the support region 21a side, that is, in a portion that partitions the free end sides of the first to fourth vibration regions 22a to 22d. . Therefore, each of the vibration regions 22a to 22d is connected by the additional thin film 81 at the free end side. Although FIG. 2 shows the additional thin film 81 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.

The additional thin film 81 is for suppressing warping of the first to fourth vibration regions 22a to 22d after the recess 10a is formed. It is preferable that the additional thin film 81 is made of a material having a low Young's modulus so that it is less likely to affect the vibrations of each of the vibration regions 22a to 22d. The thickness of the additional thin film 81 is, for example, 0.5 μm or more and 3 μm or less.

An interlayer insulating film 82 is formed on the walls of the first hole 61a and the second hole 62a. The interlayer insulating film 82 is for suppressing leakage between electrodes. The interlayer insulating film 82 is also formed on the upper surface of the upper piezoelectric film 42, and the first electrode section 61 and the second electrode section 62 are connected via the wiring film 63 formed on the upper surface of the interlayer insulating film 82. ing. 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).

In the center of the piezoelectric element, an opening 82a is formed in the interlayer insulating film 82, so that the upper electrode film 53 of the floating region 21b is exposed from the interlayer insulating film 82. The opening 82a corresponds to a first opening. Furthermore, an opening 82b is formed in the interlayer insulating film 82 at the outer periphery of the piezoelectric element, so that the upper piezoelectric film 42 of the support region 21a is exposed from the interlayer insulating film 82. The opening 82b corresponds to a second opening. The openings 82b are linear slits, and four openings 82b are formed parallel to the four sides of the top surface of the piezoelectric element. Note that the opening 82b may have another shape.

In the interlayer insulating film 82, a portion formed between the first hole 61a and the opening 82a and a portion formed on the opposite side of the opening 82a with respect to the first hole 61a have a volume. are made equal. Specifically, as shown in FIGS. 2 and 3, the region between the first hole 61a and the opening 82a in the interlayer insulating film 82 is defined as the inner region 82c, and the region between the first hole 61a and the opening 82b The volume between the inner region 82c and the outer region 82d is made equal, with the region between the inner region 82c and the outer region 82d being defined as an outer region 82d. Note that in FIG. 3, illustration of the wiring film 63 is omitted.

Also, in the interlayer insulating film 82, the portion formed between the second hole 62a and the opening 82a and the portion formed on the opposite side of the opening 82a with respect to the second hole 62a are , the volumes are made equal. Specifically, as shown in FIGS. 2 and 3, a region of the interlayer insulating film 82 between the second hole 62a and the opening 82a is defined as an inner region 82e, and a region between the second hole 62a and the opening 82b is defined as an inner region 82e. The area between them is defined as an outer area 82f, and the volumes of the inner area 82e and the outer area 82f are made equal.

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 vibration region 22a to 22d, each vibration region 22a to 22d vibrates. For example, when the free end side of each vibration region 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, by extracting the charge from the pad portion of the wiring portion 60, pressure such as sound pressure is detected. At this time, in this embodiment, the opening area of the slit 30 is reduced by the additional thin film 81. Therefore, it becomes difficult for pressure to escape from the slit 30, and the detection band can be widened.

Next, a method for manufacturing the piezoelectric element will be described with reference to FIGS. 4A to 4H. In this embodiment, an example will be described in which a piezoelectric element is manufactured using a wafer-shaped support 10, but a piezoelectric element may also be manufactured using a support 10 that is divided into chips in advance. .

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

Next, as shown in FIG. 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 placed in a portion that will become the floating region 21b. Further, the buffer layer 70 and the lower electrode film 51 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 body 10 and the vibrating section 20. patterned.

Note that the buffer layer 70 and the lower electrode film 51 are formed by a general sputtering method, a CVD (Chemical Vapor Deposition) method, or the like. Furthermore, a lower layer piezoelectric film 41, an intermediate electrode film 52, an upper layer piezoelectric film 42, and an upper layer electrode film 53, which will be described later, are also formed by a general sputtering method, CVD method, or the like.

Subsequently, as shown in FIG. 4C, a lower piezoelectric film 41 and an intermediate electrode film 52 are formed. Subsequently, as shown in FIG. 4D, an upper piezoelectric film 42 is formed to form the piezoelectric film 40. Further, the electrode film 50 is formed by forming an upper electrode film 53 and patterning it into a predetermined shape using a mask (not shown).

Subsequently, as shown in FIG. 4E, etching is performed using a mask (not shown) to form a first hole 61a that exposes the lower electrode film 51, a second hole 62a that exposes the intermediate electrode film 52, and an insulating film. A slit 30 exposing 12 is formed. Further, the piezoelectric film 40 located on the dicing line is removed to form the opening 20a, and the insulating film 12 is removed to form the opening 12a.

Subsequently, as shown in FIG. 4F, a photosensitive resin 80 is applied to the entire wafer so as to cover the support 10, piezoelectric film 40, electrode film 50, and buffer layer 70. Subsequently, as shown in FIG. 4G, by exposing the photosensitive resin 80 using a mask (not shown), the portions corresponding to the openings 82a, 82b, the first hole 61a, and the second hole 62a are exposed to light. The adhesive resin 80 is removed, and an additional thin film 81 and an interlayer insulating film 82 are formed. At this time, the openings 82a and 82b are formed so that the volumes of the inner region 82c and the outer region 82d are equal, and the volumes of the inner region 82e and the outer region 82f are equal.

Subsequently, as shown in FIG. 4H, a metal film is formed 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 wiring film 63 is formed by patterning the metal film formed on the interlayer insulating film 82. Thereby, the wiring section 60 is configured.

Thereafter, a mask (not shown) is appropriately placed and etching is performed to form the recess 10a. Then, it is divided into chips along dicing lines. As a result, the above-mentioned piezoelectric element in which the vibrating part 20 is arranged on the support body 10 is manufactured.

According to the 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, and it is possible to reduce the increase in the number of steps in manufacturing the piezoelectric element.

Further, according to the above embodiment, the following effects can be obtained.

(1) A portion of the interlayer insulating film 82 formed between the first and second holes 61a and 62a and the opening 82a, and an opening 82a for the first and second holes 61a and 62a. The part formed on the opposite side has the same volume. When the interlayer insulating film 82 is made of photosensitive resin, the interlayer insulating film 82 contracts when cured. Therefore, if the volumes of the interlayer insulating film 82 differ greatly on both sides of the first and second holes 61a and 62a, as shown in FIG. is formed asymmetrically. On the other hand, in the piezoelectric microphone, it is necessary to remove the interlayer insulating film 82 in the vibration region, and the formation of the opening 82a causes a large difference in the volume of the interlayer insulating film 82 on both sides of the first and second holes 61a and 62a. . Therefore, on one side where the interlayer insulating film 82 is thinner, the insulation properties are lowered, and on the other side where the interlayer insulating film 82 is thicker, there is a risk of poor coverage and disconnection when wiring metal is formed due to the overhang structure. In contrast, by making the volume of the interlayer insulating film 82 equal on both sides of the first and second holes 61a and 62a as described above, the interlayer insulating film 82 in the first and second holes 61a and 62a It is possible to improve the symmetry of the wires and suppress deterioration of insulation properties and disconnection.

(2) An opening 82b that exposes 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 holes 61a and 62a. There is. By forming the opening 82b in this manner, the volumes of the inner regions 82c, 82e and the outer regions 82d, 82f can be adjusted, and deterioration in insulation properties and disconnection can be suppressed.

(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. Thereby, the symmetry of the interlayer insulating film 82 in the first and second holes 61a and 62a can be improved, and deterioration in insulation properties and disconnection can be suppressed.

(4) The additional thin film 81 and the interlayer insulating film 82 are made of a photosensitive resin such as polyimide or PBO. Since the electrode thickness of a piezoelectric microphone is as thin as several tens of nanometers, for example, if TEOS (tetraethoxysilane) is used as the interlayer insulating film 82, the electrode film 50 may be damaged during patterning of the interlayer insulating film 82 by etching. On the other hand, 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, thereby suppressing damage to the electrode film 50. be able to.

(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 the piezoelectric element having such a configuration, the interlayer insulating film 82 can suppress leakage at the interface between the lower piezoelectric film 41 and the upper piezoelectric film 42.

(6) By using the piezoelectric element of this embodiment in a microphone, the microphone can have low noise and a wide band.

(Second embodiment)
A second embodiment will be described. This embodiment differs from the first embodiment in that the structure of the interlayer insulating film 82 is changed, and other aspects are the same as in the first embodiment, so only the different parts from the first embodiment will be described.

In this embodiment, a portion of the interlayer insulating film 82 is formed between the first hole 61a and the opening 82a, and a portion is formed on the opposite side of the first hole 61a from the opening 82a. The film thickness is different. Specifically, as shown in FIG. 6, a 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 an inner region 82c and an outer region 82g are defined. A portion of the outer region 82g is made thin so that the volumes of the two regions are equal.

Further, in the interlayer insulating film 82, a portion formed between the second hole 62a and the opening 82a, and a portion formed on the opposite side of the opening 82a with respect to the second hole 62a, The film thickness is different. Specifically, as shown in FIG. 6, a 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 an inner region 82e and an outer region 82h are defined. A part of the outer region 82h is made thin so that the volumes of the outer regions 82h are equal to each other.

In this embodiment, after the step shown in FIG. 4F, as shown in FIG. 7A, the photosensitive resin 80 is exposed with a small amount of light using a mask 91 that exposes the portions of the outer regions 82g and 82h to be thinned. do. Subsequently, as shown in FIG. 7B, using a mask 92 that exposes portions corresponding to the openings 12a, 20a, the first hole 61a, the second hole 62a, and the opening 82a, the process shown in FIG. 7A is performed. The photosensitive resin 80 is exposed to a larger amount of light. As a result, an interlayer insulating film 82 is formed in which the outer regions 82g and 82h are partially thinned.

This embodiment can obtain the same effects as the first embodiment from the same configuration and operation as the first embodiment.

Further, according to the above embodiment, the following effects can be obtained.

(1) The interlayer insulating film 82 has different thicknesses between the inner regions 82c and 82d and the outer regions 82g and 82h. In this way, by changing 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 becomes wider, which prevents damage to the piezoelectric element. Can be suppressed.

(Other embodiments)
Note that the present invention is not limited to the embodiments described above, and can be modified as appropriate within the scope of the claims. Furthermore, in each of the above embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is specifically stated that they are essential or where they are clearly considered essential in principle. stomach. In addition, in each of the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the constituent elements of the embodiment are mentioned, when it is clearly stated that it is essential, or when it is clearly limited to a specific number in principle. It is not limited to that specific number, except in cases where In addition, in each of the above embodiments, when referring to the shape, positional relationship, etc. of constituent elements, etc., the shape, It is not limited to positional relationships, etc.

For example, in the first embodiment, not only a configuration in which the volumes of the inner regions 82c and 82e and outer regions 82d and 82f are completely equal, but also a configuration in which the volumes are approximately equal, the inside regions 61a and 62a are The symmetry of the interlayer insulating film 82 can be improved, and deterioration in insulation properties can be suppressed.

Further, in the second embodiment, not only the configuration in which the volumes of the inner regions 82c and 82e and the outer regions 82g and 82h are completely equal but also the volume in the first and second holes 61a and 62a are substantially equal. The symmetry of the interlayer insulating film 82 can be improved, and deterioration in insulation properties can be suppressed.

In the second embodiment, depending on the location of the first and second holes 61a, 62a and the size of the opening 82a, it is possible to reduce the thickness of the inner regions 82c, 82e by thinning a part of the inner regions 82c, 82e. The volumes of the outer regions 82g and 82h may be equal to each other.

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

Further, in the second embodiment, the additional thin film 81 and the interlayer insulating film 82 may be formed by exposing the photosensitive resin 80 to light as shown in FIGS. 8A and 8B. That is, after the step shown in FIG. 4F, the portions corresponding to the openings 12a, 20a, the first hole 61a, the second hole 62a, and the opening 82a, and the portions of the outer regions 82g, 82h to be thinned are Using the exposing mask 91, the photosensitive resin 80 is exposed with a small amount of light. Subsequently, using a mask 92 that exposes portions corresponding to the openings 12a, 20a, the first hole 61a, the second hole 62a, and the opening 82a, a light amount as small as that in the step shown in FIG. 8A, or , the photosensitive resin 80 is exposed to a medium amount of light. Note that in consideration of misalignment, the methods shown in FIGS. 7A and 7B are more desirable than this method.

Further, in the second embodiment, the additional thin film 81 and the interlayer insulating film 82 may be formed by exposing the photosensitive resin 80 to light as shown in FIGS. 9A and 9B. That is, after the step shown in FIG. 4F, the photosensitive resin 80 is exposed using a mask 91 that exposes the portions corresponding to the openings 12a, 20a, 82a and the portions of the outer regions 82g, 82h to be thinned. do. Subsequently, the photosensitive resin 80 is exposed using a mask 92 that exposes portions corresponding to the openings 12a, 20a, the first hole 61a, the second hole 62a, and the opening 82a.

10 support body 20 vibrating part 30 slit 40 piezoelectric film 50 electrode film 81 additional thin film 82 interlayer insulating film

Claims (17)

A piezoelectric element in which a vibrating part (20) is arranged 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 the holes (61a, 62a) penetrating the piezoelectric film;
an interlayer insulating film (82) formed on the wall surface of the hole and on the top of the piezoelectric film to insulate the piezoelectric film and the through electrode,
The vibrating section includes the piezoelectric film and the electrode film, and has a support region (21a) supported by the support and a floating region (21b) floating from the support,
The floating region has a plurality of vibration regions (22a to 22d) partitioned 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. An opening (82a) is formed in the interlayer insulating film to expose the vibration region,
A portion of the interlayer insulating film formed between the hole and the opening and a portion formed on a side opposite to the opening with respect to the hole have the same volume. 1. The piezoelectric element according to 1. A first opening (82a) exposing the vibration region is formed in the interlayer insulating film,
1. A second opening (82b) for exposing the piezoelectric film is formed in a portion of the interlayer insulating film that is formed on a side opposite to the first opening with respect to the hole. The piezoelectric element described in . A portion of the interlayer insulating film formed between the hole and the first opening and a portion formed between the hole and the second opening have the same volume. 3. The piezoelectric element according to 3. An opening (82a) is formed in the interlayer insulating film to expose the vibration region,
2. The interlayer insulating film has a thickness different between a portion formed between the hole and the opening and a portion formed on the opposite side of the hole with respect to the opening. 3. The piezoelectric element according to 1 or 2. 6. The piezoelectric element according to claim 1, wherein the additional thin film and the interlayer insulating film are made of photosensitive resin. The piezoelectric element according to claim 6, wherein the photosensitive resin is polyimide or polybenzoxazole. The piezoelectric film has a lower piezoelectric film (41) and an upper piezoelectric film (42),
The electrode film includes a lower layer electrode film (51) formed below the lower layer piezoelectric film, an intermediate electrode film (52) formed between the lower layer piezoelectric film and the upper layer piezoelectric film, and the upper layer piezoelectric film. 8. The piezoelectric element according to claim 1, further comprising an upper electrode film (53) formed above the film. A microphone comprising the piezoelectric element according to any one of claims 1 to 7. A microphone comprising the piezoelectric element according to claim 8. A method for manufacturing a piezoelectric element in which a vibrating part (20) is arranged on a support (10),
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 hole;
forming an interlayer insulating film (82) on a wall surface of the hole and an upper part of the piezoelectric film to insulate the piezoelectric film and the through electrode;
forming a slit (30) in a floating region containing the piezoelectric film and the electrode film and floating from the support to divide 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 of manufacturing a piezoelectric element, wherein forming the interlayer insulating film and forming the additional thin film are performed simultaneously. forming an opening (82a) in the interlayer insulating film to expose the vibration region;
In forming the opening, a portion of the interlayer insulating film formed between the hole and the opening, and a portion of the interlayer insulating film formed on the opposite side of the opening from the hole. 12. The method of manufacturing a piezoelectric element according to claim 11, wherein the opening is formed so that the volume of the opening is equal to that of the opening. forming a first opening (82a) in the interlayer insulating film to expose the vibration region;
A second opening (82b) that exposes the piezoelectric film is formed in a portion of the interlayer insulating film that is formed on a side opposite to the first opening with respect to the hole. Item 12. The method for manufacturing a piezoelectric element according to item 11. In forming the first opening and forming the second opening, a portion of the interlayer insulating film formed between the hole and the first opening and the hole 14. The method of manufacturing a piezoelectric element according to claim 13, wherein the first opening and the second opening are formed so that the volume of the portion formed between the first opening and the second opening is equal. . forming an opening (82a) in the interlayer insulating film to expose the vibration region;
In forming the interlayer insulating film, the thickness of the interlayer insulating film is determined by a portion formed between the hole and the opening and a portion formed on the opposite side of the hole from the opening. 13. The method of manufacturing a piezoelectric element according to claim 11, wherein the interlayer insulating film is formed such that the interlayer insulating films are different. 16. The method of manufacturing a piezoelectric element according to claim 11, wherein the additional thin film and the interlayer insulating film are made of photosensitive resin. 17. The method for manufacturing a piezoelectric element according to claim 16, wherein the photosensitive resin is polyimide or polybenzoxazole.

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