Piezoelectric element

Abstract

To suppress a decline in connection between an electrode coating film and a through electrode.SOLUTION: A piezoelectric element includes: a support medium 10; a vibrator 20 which is disposed on an insulation film 12 of the support medium 10, includes a piezoelectric film 40 and an electrode film 50 having an electrode coating film 52 electrically connected to the piezoelectric film 40 and disposed on the piezoelectric film 40 or inside the piezoelectric film 40, the vibrator having a support region 21a supported by the support medium 10 and vibration regions 22a-22d that are floated from the support medium 10; and a through electrode 62b disposed along a stacking direction of the support medium 10 and the vibrator 20, and is electrically connected to the electrode coating film 52 at the support region 21a. A seed layer 80 is disposed at a portion facing a portion of the electrode coating film 52 connected to the through electrode 62b between the piezoelectric film 40 and the insulation film 12, in the stacking direction, the seed layer being made of material having a lattice constant closer to that of the piezoelectric film 40 than the insulation film 12 or material easier to cause the piezoelectric film 40 to be self-aligned than the insulation film 12.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a piezoelectric element having a vibration portion. [Background technology]

[0002] Conventionally, piezoelectric elements having a vibration part have been proposed (for example, see Patent Document 1). Specifically, this piezoelectric element is configured by arranging a vibration part having a piezoelectric film and an electrode film electrically connected to the piezoelectric film on a support.

[0003] More specifically, the support is configured by laminating an oxide film on a support substrate, and the vibration part is disposed on the oxide film. A recess is formed in the support, and the vibration part is configured to have a support region supported on the support and a floating region floating from the support. The electrode film is disposed in or on the piezoelectric film and extends from the floating region to the support region, and has an electroded film in the support region that is electrically connected to a through electrode aligned in the stacking direction of the support and the vibration part. The through electrode is disposed in a hole that exposes the electroded film along the stacking direction of the support and the vibration part. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5936154 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above piezoelectric element, since the vibration part is disposed on the oxide film, the crystallinity of the piezoelectric film is easily deteriorated, and the crystallinity of the electrode film disposed on the piezoelectric film is also easily deteriorated. When connecting the through electrode to the electrode film, a hole is formed to expose the electrode film, and the through electrode is disposed in the hole. However, if the crystallinity of the electrode film is deteriorated, the electrode film may be over-etched when the hole is formed, and the bond between the through electrode and the electrode film may be deteriorated.

[0006] In view of the above, an object of the present invention is to provide a piezoelectric element capable of suppressing a decrease in the bondability between an electrode film and a through electrode. [Means for solving the problem]

[0007] In claim 1 for achieving the above object, a piezoelectric element is provided having a vibration part (20) arranged on a support (10), the vibration part including a support having a support substrate (11) and an insulating film (12) arranged on the support substrate, a piezoelectric film (40) arranged on the insulating film of the support, and an electrode film (50) having an electroded film (52, 53) electrically connected to the piezoelectric film and arranged on or within the piezoelectric film, a support region (21a) supported by the support and a vibration region (22a to 22d) connected to the support region and floating from the support, and through electrodes (62b, 63b) arranged along a stacking direction of the support and the vibration part and electrically connected to the electroded film at the support region, and a seed layer (80) made of a material closer to the lattice constant of the piezoelectric film than the insulating film, or made of a material with which the piezoelectric film is more easily self-aligned than the insulating film, is arranged between the piezoelectric film and the insulating film and in a portion facing the portion of the electroded film connected to the through electrode in the stacking direction. The vibration section has, in the vibration region, a buffer layer (70) arranged closer to the support than the piezoelectric film, and a base electrode film (51) as an electrode film arranged between the buffer layer and the piezoelectric film, and the seed layer is configured by extending the buffer layer and the base electrode film to the support region. .

[0008] According to this, a seed layer is disposed on a portion of the electroded film that faces a portion that is connected to the through electrode. Therefore, it is possible to suppress the crystallinity of the piezoelectric film disposed on the seed layer from collapsing, and it is possible to suppress the crystallinity of the portion of the electroded film that is connected to the through electrode from collapsing. Therefore, it is possible to suppress the deterioration of the connection reliability between the electroded film and the through electrode.

[0009] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view of a piezoelectric element according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4A] 5A to 5C are cross-sectional views showing a manufacturing process of the 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 a 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] 4E is a cross-sectional view showing a 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] 4F; FIG. 4C is a cross-sectional view showing a manufacturing process of the piezoelectric element subsequent to FIG. 4F; [Diagram 5] FIG. 6 is a cross-sectional view of a piezoelectric element according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view of a piezoelectric element according to a third embodiment. [Figure 7] FIG. 13 is a cross-sectional view of a piezoelectric element according to a fourth embodiment. [Figure 8]FIG. 13 is a cross-sectional view of a piezoelectric element according to a fifth embodiment. [Figure 9] FIG. 13 is a cross-sectional view of a piezoelectric element according to a sixth embodiment. [Figure 10] FIG. 13 is a cross-sectional view of a piezoelectric element according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0012] (First embodiment) The piezoelectric element of the first embodiment will be described with reference to Fig. 1 to Fig. 3. The piezoelectric element of this embodiment is suitable for use in a piezoelectric microphone mounted on a smartphone, an AI (abbreviation of artificial intelligence) speaker, etc. The piezoelectric element of this embodiment is also suitable for use in an ultrasonic sensor, etc.

[0013] 1 to 3, the piezoelectric element includes a support 10 and a vibration 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.

[0014] The support 10 is formed with a recess 10a for floating 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. The recess 10a in this embodiment has an open end on the vibration section 20 side that is rectangular in plan view. Therefore, the entire floating region 21b is rectangular in plan view.

[0015] In addition, the vibration part 20 of this embodiment has an opening 20a formed in its outer edge portion to expose the outer edge portion of the insulating film 12. The insulating film 12 has an opening 12a formed in its outer edge portion to expose the outer edge portion of the support substrate 11. Therefore, the outer edge portion of the support substrate 11 is exposed from the insulating film 12 and the vibration part 20. The opening 12a formed in the insulating film 12 and the opening 20a formed in the vibration part 20 are intended to facilitate the dicing process when manufacturing the piezoelectric element, and are not necessarily required to be formed. Hereinafter, the region in the piezoelectric element where the vibration part 20 is arranged is referred to as the element region R.

[0016] In the floating region 21b, a slit 30 is formed penetrating the floating region 21b in the thickness direction. In this embodiment, the slit 30 is formed so as to divide the floating region 21b into four. More specifically, two slits 30 are formed so as to pass through the center C of the floating region 21b and extend toward the opposite corners of the floating region 21b. In other words, the slits 30 are formed so as to extend from each corner of the floating region 21b, which is rectangular in plan view, toward the center C, and intersect at the center C. As a result, the floating region 21b is separated into first to fourth vibration regions 22a to 22d, which are substantially triangular in plan view. Although not particularly limited, in this embodiment, the interval between the vibration regions 22a to 22d (i.e., the width of the slit 30) is about 1 μm. In addition, the slits 30 in this embodiment are extended to the support region 21a, but may be formed so as to terminate within the floating region 21b.

[0017] Moreover, by being configured as described above, the first to fourth vibrating regions 22a to 22d are configured as cantilevers whose ends on the support region 21a side are fixed ends and whose tips on the opposite side to the support region 21a are free ends.

[0018] The vibration section 20 is configured to have a piezoelectric film 40 and an electrode film 50 connected to the piezoelectric film 40. 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 lower piezoelectric film 41 and the upper piezoelectric film 42 are made of lead-free piezoelectric ceramics such as aluminum scandium nitride (hereinafter simply referred to as ScAlN) and aluminum nitride (AlN). The lower piezoelectric film 41 and the upper piezoelectric film 42 are made of lead zirconate titanate (PZT) or the like.

[0019] 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 mainly composed of any one of titanium (Ti), platinum (Pt), aluminum (Al), ruthenium (Ru), etc., in addition to molybdenum. These materials constituting the electrode film 50 are materials whose lattice number is closer to that of the piezoelectric film 40 than that of the insulating film 12.

[0020] 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 disposed to face each other with the lower piezoelectric film 41 in between. The intermediate electrode film 52 and the upper electrode film 53 are disposed to face each other with the upper piezoelectric film 42 in between.

[0021] Here, the piezoelectric element of this embodiment outputs, as a detection signal, the charge that changes as each of the vibration regions 22a to 22d vibrates, as described later. The piezoelectric element of this embodiment is configured to output the change in charge in the first to fourth vibration regions 22a to 22d as one pressure detection signal. Specifically, the electrode films 50 of the first to fourth vibration regions 22a to 22d are electrically connected in series via a wiring portion not shown. More specifically, the first vibration region 22a to 22d has a so-called bimorph structure, and the lower electrode films 51, the intermediate electrode films 52, and the upper electrode films 53 formed in each of the vibration regions 22a to 22d are connected in parallel, while the vibration regions 22a to 22d are connected in series.

[0022] The piezoelectric element is formed with a first electrode portion 61 and a second electrode portion 62 so as to be connected to the end portions of the electrode films 50 of the first to fourth vibration regions 22a to 22d connected in series. Specifically, the first electrode portion 61 is configured to have a first through electrode 61b and a first pad portion 61c, and is formed to be connected to the lower layer electrode film 51 and the upper layer electrode film 53 formed in the first vibration region 22a in the support region 21a. The second electrode portion 62 is configured to have a second through electrode 62b and a second pad portion 62c, and is formed to be electrically connected to the intermediate electrode film 52 formed in the fourth vibration region 22d in the support region 21a.

[0023] 2, the lower electrode film 51 and the upper electrode film 53 formed in the first vibration region 22a are extended to the support region 21a. A first hole 61a is formed to penetrate the upper piezoelectric film 42 and the lower piezoelectric film 41 to expose the lower electrode film 51, and the first through electrode 61b is disposed in the first hole 61a so as to be electrically connected to the lower electrode film 51. The first pad 61c is disposed on the upper piezoelectric film 42 so as to be electrically connected to the first through electrode 61b and the upper electrode film 53.

[0024] 3, the intermediate electrode film 52 formed in the fourth vibration region 22d is extended to the support region 21a. A second hole 62a is formed to penetrate the upper layer piezoelectric film 42 and expose the intermediate electrode film 52, and the second through electrode 62b is disposed in the second hole 62a so as to be electrically connected to the intermediate electrode film 52. The second pad 62c is disposed on the upper layer piezoelectric film 42 so as to be electrically connected to the second through electrode 62b. In this embodiment, the intermediate electrode film 52 corresponds to the electroded film, and the lower layer electrode film 51 corresponds to the base electrode film.

[0025] Furthermore, the vibration section 20 of this embodiment has a buffer layer 70 on the support 10 side, in which the lower piezoelectric film 41 and the lower electrode film 51 are disposed. The buffer layer 70 is made of a material having a lattice constant closer to that of the lower electrode film 51 than that of the insulating film 12. In other words, the buffer layer 70 is made of a material with which the lower electrode film 51 is more easily lattice-matched than that of the insulating film 12. Such a buffer layer 70 is made of, for example, aluminum nitride (AlN) or the like.

[0026] Here, the buffer layer 70 of this embodiment is formed on the entire portion that becomes the floating region 21b. The buffer layer 70 is formed so as to face the portion of the intermediate electrode film 52 that is connected to the second through electrode 62b in the stacking direction (hereinafter also simply referred to as the stacking direction) of the support 10 and the vibration section 20. The lower electrode film 51 is formed on the entire region on the buffer layer 70, and is formed so as to include a portion that faces the portion of the intermediate electrode film 52 that is connected to the second through electrode 62b. That is, the buffer layer 70 and the lower electrode film 51 are arranged between the lower piezoelectric film 41 and the support 10 (i.e., the insulating film 12) in the portion that faces the portion of the intermediate electrode film 52 that is connected to the second through electrode 62b.

[0027] Hereinafter, the layer disposed between the lower-layer piezoelectric film 41 and the support 10 (i.e., the insulating film 12) in a portion facing the portion of the intermediate electrode film 52 connected to the second through electrode 62b is also referred to as a seed layer 80. For this reason, the seed layer 80 of this embodiment is composed of the lower-layer electrode film 51 and the buffer layer 70. The seed layer 80 of this embodiment has an area larger than the second through electrode 62b (i.e., the second hole portion 62a) in the stacking direction, and is formed so that the second through electrode 62b is located within the seed layer 80.

[0028] In this embodiment, the buffer layer 70 and the lower electrode film 51 are not formed up to the outer edge of the element region R. Therefore, the outer edge portion of the lower piezoelectric film 41 is disposed directly on the insulating film 12.

[0029] The above is the configuration of the piezoelectric element in this embodiment. When pressure such as sound pressure is applied to each of the vibration regions 22a-22d of such a piezoelectric element, the vibration regions 22a-22d vibrate. Then, for example, when the tip end side (i.e., the free end side) of each of the vibration regions 22a-22d is displaced upward, a tensile stress is generated in the lower piezoelectric film 41, and a compressive stress is generated in the upper piezoelectric film 42. Therefore, by extracting the charge from the first electrode portion 61 and the second electrode portion 62, a pressure such as sound pressure can be detected.

[0030] Next, a method for manufacturing the piezoelectric element will be described with reference to Figures 4A to 4G. Note that, in this embodiment, an example in which the piezoelectric element is manufactured using a wafer-shaped support 10 will be described, but the piezoelectric element may be manufactured using a support 10 that has been divided into chip units in advance.

[0031] 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.

[0032] 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). In this embodiment, the buffer layer 70 and the lower electrode film 51 are patterned so as to be disposed in a portion that becomes the floating region 21b. The buffer layer 70 and the lower electrode film 51 are 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 (i.e., a portion that constitutes the seed layer 80).

[0033] The buffer layer 70 and the lower electrode film 51 are formed by a general sputtering method, a CVD (abbreviation of 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.

[0034] 4C, the lower piezoelectric film 41 and the intermediate electrode film 52 are formed. At this time, the lower electrode film 51 is made of molybdenum. Therefore, when the lower piezoelectric film 41 is formed on the lower electrode film 51 as the base film, the difference in the number of lattices between the lower piezoelectric film 41 and the lower electrode film 51 is smaller than when the lower piezoelectric film 41 is formed on the insulating film 12 as the base film. Therefore, in the portion on the lower electrode film 51, the lower piezoelectric film 41 and the lower electrode film 51 are easily lattice matched, so that the crystallinity of the lower piezoelectric film 41 is less likely to be broken, and the crystallinity of the portion of the lower piezoelectric film 41 located on the seed layer 80 is also less likely to be broken. As a result, the crystallinity of the intermediate electrode film 52 is less likely to be broken in the portion facing the lower electrode film 51 across the lower piezoelectric film 41. That is, the crystallinity of the intermediate electrode film 52 is less likely to be broken in the portion facing the seed layer 80.

[0035] In addition, since the crystallinity of the lower piezoelectric film 41 and the intermediate electrode film 52 is less likely to be lost in the portions formed on the lower electrode film 51 as a base film, the crystallinity is less likely to be lost overall in the floating region 21b.

[0036] 4D, an upper piezoelectric film 42 is formed to form the piezoelectric film 40. An upper electrode film 53 is formed and patterned into a predetermined shape using a mask (not shown), to form the electrode film 50.

[0037] Next, as shown in FIG. 4E, the second hole 62a exposing the intermediate electrode film 52 is formed. At this time, as described above, the crystallinity of the intermediate electrode film 52 facing the seed layer 80 is suppressed from collapsing. That is, the crystallinity of the intermediate electrode film 52 exposed from the second hole 62a is suppressed from collapsing. In other words, the crystallinity of the intermediate electrode film 52 connected to the second through electrode 62b is suppressed from collapsing. Therefore, when forming the second hole 62a, the intermediate electrode film 52 can be suppressed from being over-etched too much. In addition, since the intermediate electrode film 52 can be suppressed from being over-etched too much, it is not necessary to perform visual inspection many times when forming the second hole 62a, and an increase in the manufacturing process can be suppressed. Although not particularly shown, in this process, the first hole 61a exposing the lower electrode film 51 is also formed in a cross section different from that of FIG. 4E.

[0038] Next, as shown in Fig. 4F, a metal film is formed so as to fill the second hole 62a, thereby forming a second through electrode 62b. Then, the metal film formed on the upper piezoelectric film 42 is patterned to form a second pad portion 62c. In addition, in a cross section different from that of Fig. 4F, a metal film is formed so as to fill the first hole 61a, thereby forming a first through electrode 61b, and the metal film formed on the upper piezoelectric film 42 is patterned to form a first pad portion 61c. In this way, the first electrode portion 61 and the second electrode portion 62 are configured.

[0039] Thereafter, as shown in FIG. 4G, a mask (not shown) is appropriately placed and etching is performed to form slits 30 and recesses 10a. In this embodiment, in order to facilitate the dicing process, the piezoelectric film 40 located on the dicing line is removed to form openings 20a, and the insulating film 12 is removed to form openings 12a. Then, the substrate is divided into chip units along the dicing line. This completes the manufacture of the piezoelectric element in which the vibration portion 20 is disposed on the support 10.

[0040] In this embodiment, an example has been described in which piezoelectric elements are manufactured using a wafer-like support 10, but piezoelectric elements may also be manufactured using a support substrate 11 that has been divided into chip units in advance.

[0041] According to the present embodiment described above, the seed layer 80 is disposed between the lower-layer piezoelectric film 41 and the insulating film 12 in a portion facing the portion of the intermediate electrode film 52 connected to the second through-electrode 62b. This makes it possible to suppress the crystallinity of the lower-layer piezoelectric film 41 disposed on the seed layer 80 from collapsing, and to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through-electrode 62b from collapsing. This makes it possible to suppress a decrease in the connection reliability between the intermediate electrode film 52 and the second through-electrode 62b.

[0042] Moreover, since it is possible to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b from being destroyed, it is possible to suppress over-etching of the intermediate electrode film 52 when forming the second hole portion 62a that exposes the intermediate electrode film 52. Therefore, it is possible to suppress a decrease in the connection reliability between the intermediate electrode film 52 and the second through electrode 62b.

[0043] Furthermore, since over-etching of the intermediate electrode film 52 can be suppressed, when forming the second hole portion 62a that exposes the intermediate electrode film 52, it is not necessary to repeatedly check the depth of the second hole portion 62a, thereby simplifying the manufacturing process.

[0044] Moreover, since the intermediate electrode film 52 can be prevented from being over-etched, when a piezoelectric element is manufactured using the wafer-like support 10 as in this embodiment, the etching variation for each location where the second hole portion 62a is formed can be reduced. Therefore, the occurrence of a defect in which the second hole portion 62a is not properly formed can be prevented, and a decrease in yield can be prevented.

[0045] (1) In the present embodiment, the seed layer 80 has an area larger than that of the second through electrode 62b in the stacking direction. Therefore, even if the second through electrode 62b (i.e., the second hole portion 62a) is misaligned, it is possible to prevent a defect in which the seed layer 80 is not disposed in a portion of the intermediate electrode film 52 that faces a portion connected to the second through electrode 62b.

[0046] (2) In this embodiment, the seed layer 80 is composed of the buffer layer 70 and the lower electrode film 51. Therefore, the number of manufacturing steps can be reduced compared to when the seed layer 80 is composed of a material different from that of the buffer layer 70 and the lower electrode film 51.

[0047] Second embodiment A second embodiment will be described. This embodiment is different from the first embodiment in that the shapes of the buffer layer 70 and the lower electrode film 51 are changed. As the rest is similar to the first embodiment, a description thereof will be omitted here.

[0048] 5, in the piezoelectric element of this embodiment, the buffer layer 70 and the lower electrode film 51 are extended to the outer edge of the element region R. In other words, the buffer layer 70 and the lower electrode film 51 are formed over the entire support region 21a and the entire floating region 21b. The entire region of the lower piezoelectric film 41 is formed on the lower electrode film 51.

[0049] According to the present embodiment described above, the seed layer 80 is disposed between the lower piezoelectric film 41 and the insulating film 12 in a portion facing the portion of the intermediate electrode film 52 connected to the second through electrode 62b. This makes it possible to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b from being broken, and it is possible to obtain the same effect as the first embodiment.

[0050] (1) According to this embodiment, the buffer layer 70 and the lower electrode film 51 are formed up to the outer edge of the element region R. The entire region of the lower piezoelectric film 41 is formed on the lower electrode film 51. Therefore, it is possible to prevent the crystallinity from being broken in the entire region of the lower piezoelectric film 41 and the intermediate electrode film 52, and it is possible to improve reliability.

[0051] Third embodiment A third embodiment will be described. This embodiment is different from the second embodiment in that the shapes of the buffer layer 70 and the lower electrode film 51 are changed. As the rest is the same as the second embodiment, a description thereof will be omitted here.

[0052] The piezoelectric element of this embodiment is configured as shown in Fig. 6. Specifically, the buffer layer 70 and the lower electrode film 51 are partitioned by a partitioning slit 81 between a portion that will become the seed layer 80 and a portion that will be disposed in the floating region 21b. In other words, in this embodiment, the buffer layer 70 and the lower electrode film 51 include a portion that will be disposed on the support region 21a and become the seed layer 80, and the portion that faces the intermediate electrode film 52 in the support region 21a and the portion that will be disposed in the floating region 21b are partitioned by the partitioning slit 81.

[0053] According to the present embodiment described above, the seed layer 80 is disposed between the lower piezoelectric film 41 and the insulating film 12 in a portion facing the portion of the intermediate electrode film 52 connected to the second through electrode 62b. This makes it possible to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b from being broken, and it is possible to obtain the same effect as the first embodiment.

[0054] (1) In this embodiment, the buffer layer 70 and the lower electrode film 51 are partitioned by partitioning slits 81 between the portion that will become the seed layer 80 and the portion that will be disposed in the floating region 21b. This makes it possible to suppress a decrease in detection accuracy. That is, since the portion that will become the seed layer 80 faces the intermediate electrode film 52, a parasitic capacitance is formed between the lower electrode film 51 and the intermediate electrode film 52 that form the seed layer 80. Therefore, by forming the partitioning slits 81, it is possible to suppress a decrease in detection accuracy due to the parasitic capacitance caused by the seed layer 80.

[0055] (Fourth embodiment) A fourth embodiment will be described. This embodiment is different from the second embodiment in that the configuration of the seed layer 80 is changed. As the rest is similar to the second embodiment, a description thereof will be omitted here.

[0056] The piezoelectric element of this embodiment is configured as shown in Fig. 7. Specifically, the buffer layer 70 extends to the outer edge of the element region R as in the second embodiment, but the lower electrode film 51 does not extend to the portion facing the second through electrode 62b. That is, the seed layer 80 of this embodiment is configured from the portion of the buffer layer 70 facing the second through electrode 62b. In other words, the seed layer 80 is configured only from the buffer layer 70. The buffer layer 70 is made of aluminum nitride, which is a material whose lattice constant is closer to that of the lower piezoelectric film 41 than the insulating film 12.

[0057] According to the present embodiment described above, the seed layer 80 is disposed between the lower piezoelectric film 41 and the insulating film 12 in a portion facing the portion of the intermediate electrode film 52 connected to the second through electrode 62b. This makes it possible to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b from being broken, and it is possible to obtain the same effect as the first embodiment.

[0058] (1) In this embodiment, the seed layer 80 is composed of only the buffer layer 70. This makes it possible to prevent unnecessary parasitic capacitance from being generated in the support region 21a. Therefore, even if the partition slits 81 are not formed as in the third embodiment, it is possible to prevent a decrease in detection accuracy.

[0059] Fifth embodiment A fifth embodiment will be described. This embodiment differs from the first embodiment in that it does not include the buffer layer 70. As the rest is similar to the first embodiment, a description thereof will be omitted here.

[0060] 8, the piezoelectric element of this embodiment does not include a buffer layer 70. The lower electrode film 51 is formed to include a portion that faces a portion of the intermediate electrode film 52 that is connected to the second through electrode 62b. Therefore, the seed layer 80 of this embodiment is composed of the portion of the lower electrode film 51 that faces the second through electrode 62b. In other words, the seed layer 80 of this embodiment is composed of only the lower electrode film 51.

[0061] According to the present embodiment described above, the seed layer 80 is disposed between the lower piezoelectric film 41 and the insulating film 12 in a portion facing the portion of the intermediate electrode film 52 connected to the second through electrode 62b. This makes it possible to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b from being broken, and it is possible to obtain the same effect as the first embodiment.

[0062] (1) Even if the seed layer 80 is configured only by the lower electrode film 51 as in this embodiment, the formation of the seed layer 80 can suppress the breakdown of crystallinity in the portion of the intermediate electrode film 52 that is connected to the second through electrode 62b. Therefore, the same effects as those of the first embodiment can be obtained.

[0063] Sixth embodiment A sixth embodiment will be described. This embodiment is different from the first embodiment in that the configuration of the seed layer 80 is changed. As the rest is similar to the first embodiment, a description thereof will be omitted here.

[0064] 9, in the piezoelectric element of the present embodiment, the seed layer 80 is made of a material different from the buffer layer 70 and the lower electrode film 51. In the present embodiment, the seed layer 80 is made of ScAlN having a lower concentration of scandium than the piezoelectric film 40.

[0065] The piezoelectric film 40 is made of ScAlN, and is high-concentration ScAlN with a scandium concentration of 30% or more.

[0066] According to the present embodiment described above, the seed layer 80 is disposed between the lower piezoelectric film 41 and the insulating film 12 in a portion facing the portion of the intermediate electrode film 52 connected to the second through electrode 62b. This makes it possible to suppress the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b from being broken, and it is possible to obtain the same effect as the first embodiment.

[0067] (1) In this embodiment, the seed layer 80 is made of ScAlN having a lower concentration of scandium than the piezoelectric film 40. Therefore, even if the lower piezoelectric film 41 is made of ScAlN having a higher concentration of scandium, the crystallinity of the lower piezoelectric film 41 on the seed layer 80 can be prevented from being destroyed.

[0068] That is, when ScAlN is used as the lower piezoelectric film 41, the lattice constant increases as the concentration of scandium increases. According to the study by the present inventors, when the lower piezoelectric film 41 is made of high-concentration ScAlN with a scandium concentration of 30% or more, it has been confirmed that even if the lower electrode film 51 is made of molybdenum or the like, the crystallinity of the lower piezoelectric film 41 may not be sufficiently suppressed from being broken. For this reason, in this embodiment, the seed layer 80 is made of ScAlN with a lower concentration of scandium than the piezoelectric film 40. As a result, since the lower piezoelectric film 41 is formed on the same material, the crystallinity of the lower piezoelectric film 41 on the seed layer 80 can be suppressed from being broken. Therefore, the crystallinity of the portion of the intermediate electrode film 52 connected to the second through electrode 62b can be suppressed from being broken, and the connection reliability between the intermediate electrode film 52 and the second through electrode 62b can be suppressed from being reduced. Although the above description has been given of the case where the piezoelectric film 40 is made of high-concentration ScAlN, this embodiment is also applicable to the case where the piezoelectric film 40 is made of low-concentration ScAlN.

[0069] (Modification of the sixth embodiment) A modified example of the sixth embodiment will be described. In the sixth embodiment, the seed layer 80 may be made of other materials. For example, the seed layer 80 may be made of an oxide of a metal material mainly composed of any one of molybdenum, titanium, platinum, aluminum, ruthenium, etc. In addition, the oxide here includes different valences and is not limited to an oxide of a specific valence. In addition, the seed layer 80 may be made of, for example, an amorphous material. However, when the seed layer 80 is made of these materials, it is preferable that the lower piezoelectric film 41 is made of low-concentration ScAlN, AlN, etc.

[0070] When the seed layer 80 is made of such a material, the inventors have confirmed that the lower piezoelectric film 41 disposed on the seed layer 80 is less susceptible to the influence of the seed layer 80 that serves as the base film, and the crystallinity is less likely to be lost due to self-alignment. For this reason, the seed layer 80 may be made of a material with which the lower piezoelectric film 41 is more likely to self-align than the insulating film 12.

[0071] Seventh embodiment A seventh embodiment will be described. This embodiment is different from the first embodiment in that the configuration of the vibration section 20 is changed. As the rest is similar to the first embodiment, a description thereof will be omitted here.

[0072] 10, the piezoelectric element of this embodiment has a single layer of piezoelectric film 40, and does not include an intermediate electrode film 52. An insulating film 90 is disposed on the piezoelectric film 40 so as to cover the upper electrode film 53.

[0073] A hole 63a is formed in the insulating film 90 so as to penetrate the insulating film 90 and expose the upper electrode film 53, and a through electrode 63b connected to the upper electrode film 53 is disposed in the hole 63a. A pad portion 63c is formed on the insulating film 90 so as to be electrically connected to the through electrode 63b. In this embodiment, the upper electrode film 53 corresponds to the electroded film.

[0074] The buffer layer 70 and the lower electrode film 51 are formed to include a portion facing a portion connected to the through electrode 63b in the upper electrode film 53. The seed layer 80 is composed of the buffer layer 70 and a portion facing a portion connected to the through electrode 63b in the upper electrode film 53, of the lower electrode film 51. Note that the seed layer 80 in this embodiment is configured to have an area larger than that of the through electrode 63b in the stacking direction.

[0075] According to the present embodiment described above, the seed layer 80 is disposed between the piezoelectric film 40 and the insulating film 12 in a portion facing the portion of the upper electrode film 53 connected to the through electrode 63b. This makes it possible to suppress the crystallinity of the portion of the upper electrode film 53 connected to the through electrode 63b from being broken, and it is possible to obtain the same effect as the first embodiment.

[0076] (1) As in this embodiment, the piezoelectric film 40 may be configured as one layer. Even in such a piezoelectric element, the same effect as in the first embodiment can be obtained by suppressing the breakdown of the crystallinity of the upper electrode film 53 disposed on the piezoelectric film 40 and connected to the through electrode 63b.

[0077] (Other embodiments) Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

[0078] For example, in each of the above embodiments, the floating region 21b may have a polygonal planar shape such as a pentagon, hexagon, octagon, etc., instead of a rectangular shape. The number of vibration regions 22a to 22d formed in the floating region 21b can be changed as appropriate. Furthermore, the piezoelectric element may have a polygonal planar shape such as a pentagon, hexagon, etc., instead of a rectangular shape.

[0079] In each of the above embodiments, the opening 20a formed in the vibration portion 20 and the opening 12a formed in the insulating film 12 may not be formed in the piezoelectric element.

[0080] Furthermore, in each of the above embodiments, each of the vibration regions 22a to 22d may output the respective electric charges as detection signals. In this case, a first electrode portion 61 is connected to the lower electrode film 51 and the upper electrode film 53 of each of the vibration regions 22a to 22d, and a second electrode portion 62 is connected to the intermediate electrode film 52 of each of the vibration regions 22a to 22d.

[0081] In the first to sixth embodiments, the seed layer 80 may have an area smaller than that of the second through electrode 62b in the stacking direction. Similarly, in the seventh embodiment, the seed layer 80 may have an area smaller than that of the through electrode 63b in the stacking direction.

[0082] The above embodiments may be combined. For example, the second embodiment may be combined with the sixth embodiment, and the seed layer 80 may be formed up to the outer edge. In this case, the seed layer 80 may be disposed on the entire region of the insulating film 12, which is different from the region where the buffer layer 70 is disposed. The third embodiment may be combined with the fifth embodiment, and the partitioning slits 81 may be formed. The second to sixth embodiments may be combined with the seventh embodiment, and the piezoelectric element may have a piezoelectric film 40 composed of a single layer. [Explanation of symbols]

[0083] 10 Support 11 Support substrate 12 Insulating film 20 Vibration section 22a~22d 1st~4th vibration area 40 Piezoelectric film 50 Electrode membrane 51 Lower electrode film (base electrode film) 52, 53 Electrode film (middle electrode film, upper electrode film) 62b, 63b 2nd and 3rd through electrodes 80 Seed Layer

Claims

1. A piezoelectric element having a vibration part (20) disposed on a support (10), The support body has a support substrate (11) and an insulating film (12) disposed on the support substrate; the vibration section includes an electrode film (50) disposed on an insulating film on the support, the electrode film (50) having a piezoelectric film (40) and an electroded film (52, 53) electrically connected to the piezoelectric film and disposed on or within the piezoelectric film, the vibration section having a support region (21a) supported by the support and vibration regions (22a to 22d) connected to the support region and suspended from the support; a through electrode (62b, 63b) disposed along a stacking direction of the support body and the vibration portion and electrically connected to the electrode film in the support region, a seed layer (80) is disposed between the piezoelectric film and the insulating film, in a portion facing a portion of the electroded film connected to the through electrode in the stacking direction, the seed layer (80) being made of a material having a lattice constant closer to that of the piezoelectric film than the insulating film, or made of a material with which the piezoelectric film is more easily self-aligned than the insulating film; the vibration section has, in the vibration region, a buffer layer (70) arranged closer to the support than the piezoelectric film, and a base electrode film (51) as the electrode film arranged between the buffer layer and the piezoelectric film; The seed layer is a piezoelectric element in which the buffer layer and the base electrode film are extended to the support region.

2. The piezoelectric element according to claim 1 , wherein the seed layer has an area larger than a portion of the electroded film that is connected to the through electrode in the stacking direction.

3. The piezoelectric element according to claim 1 , wherein the seed layer extends to an outer edge of the vibration portion.

4. 4. A piezoelectric element as described in any one of claims 1 to 3, wherein the underlying electrode film is partitioned by a partitioning slit (81) formed between the portion constituting the seed layer and the portion formed in the vibration region.

5. 5. The piezoelectric element according to claim 1, wherein the seed layer is made of a metal material containing, as a main component, any one of molybdenum, titanium, platinum, aluminum, and ruthenium.

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