Piezoelectric element

Abstract

To provide a piezoelectric element capable of suppressing a decrease in reliability.SOLUTION: An electrode film 60 is formed from a floating region 21b to a support region 21a, and an electrode portion 81 and the electrode film 60 connected to the electrode portion 81 each have a portion exposed to the outside, the electrode portion 81 includes a first wiring portion 811 and a second wiring portion 812 electrically connected to the first wiring portion 811 and constituting a pad portion 101, and the first wiring portion 811 is made of a material having a greater ionization tendency than the second wiring portion 812 and the electrode film 60.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to piezoelectric elements. [Background technology]

[0002] Piezoelectric elements having a vibrating portion have been proposed in the past (see, for example, Patent Document 1). Specifically, this piezoelectric element has a configuration in which a vibrating portion having a piezoelectric film and an electrode film electrically connected to the piezoelectric film is stacked on a support. The piezoelectric element has a recess formed in the support, and the vibrating portion has a floating region that floats above the support and can vibrate, and a support region that is disposed on the support and supported by the support. The electrode film is formed in the floating region and extends from the floating region to the support region.

[0003] The piezoelectric element also has an electrode portion formed in the support region for connection to an external circuit. More specifically, the electrode portion has a wiring portion that is connected to the electrode film through a hole that exposes the electrode film extending from the floating region to the support region. The portion of the wiring portion that is disposed on the piezoelectric film is used as a pad portion for connection to an external circuit.

[0004] The piezoelectric film is made of, for example, scandium aluminum nitride, and the electrode film is made of molybdenum, which has a small difference in lattice constant from scandium aluminum nitride. The wiring portion is made of aluminum, gold, or the like.

[0005] When the floating region of the piezoelectric element vibrates, the charge in the piezoelectric film that constitutes the floating region changes, and this charge is output from the electrode film through the pad portion to an external circuit.

[0006] The piezoelectric element is manufactured by depositing the piezoelectric film and electrode film in this order, then placing a mask made of resist or the like, and appropriately patterning the film by etching or the like, and then peeling off the mask. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2023-044406 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the inventors of the present invention have investigated the above-mentioned piezoelectric element and found that immersing the piezoelectric element in a stripping solution during mask removal can cause a galvanic current to flow, potentially reducing reliability. Galvanic current refers to the current that flows when each metal constituting a dissimilar metal bond is exposed to a stripping solution. Therefore, corrosion caused by galvanic current can occur when each metal constituting a dissimilar metal bond is exposed to the outside.

[0009] For example, when the electrode film is made of molybdenum and the wiring is made of gold, it has been confirmed that molybdenum, which has a high ionization tendency, corrodes due to the flow of galvanic current.Also, when the electrode film is made of molybdenum and the wiring is made of aluminum, it has been confirmed that aluminum, which has a high ionization tendency, corrodes due to the flow of galvanic current.

[0010] If the electrode film corrodes, it may become difficult to detect changes in the charge of the floating region using the electrode film, which may reduce reliability. Furthermore, if the electrode film corrodes, the overall balance of the floating region may be disrupted, causing the floating region to warp, which may reduce reliability.

[0011] Furthermore, if the portion of the wiring that will become the pad portion corrodes, it becomes difficult to perform wire bonding for connecting to an external circuit, and reliability may decrease.

[0012] An object of the present disclosure is to provide a piezoelectric element that can suppress a decrease in reliability. [Means for solving the problem]

[0013] According to one aspect of the present disclosure, a piezoelectric element comprises a support (10), a vibration section (20) arranged on the support and including a piezoelectric film (50) and an electrode film (60) connected to the piezoelectric film, the vibration section (20) having a support region (21a) supported by the support and a floating region (21b) connected to the support region and floating above the support, and an electrode section (81) arranged on the support region and including a pad section (101) electrically connected to the electrode film and connected to an external circuit, the electrode film being formed from the floating region to the support region, the electrode section and the electrode film connected to the electrode section each having a portion exposed to the outside, the electrode section having a first wiring section (811) and a second wiring section (812) electrically connected to the first wiring section and constituting the pad section, the first wiring section being made of a material having a greater ionization tendency than the second wiring section and the electrode film.

[0014] According to this, the first wiring portion is made of a material with the greatest ionization tendency. This prevents corrosion of the electrode film, and prevents a decrease in detection accuracy due to an inability to output the charge in the floating region. Furthermore, since corrosion of the electrode film can be prevented, it is possible to prevent the floating region from being out of balance as a whole and warping of the floating region. Furthermore, corrosion of the second wiring portion can be prevented, and it is possible to prevent a poor connection with an external circuit due to insufficient strength of the wire-bonded pad portion. Therefore, it is possible to prevent a decrease in reliability.

[0015] 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]

[0016] [Figure 1] FIG. 2 is a cross-sectional view of the piezoelectric element according to the first embodiment. [Figure 2] FIG. 2 is a plan view of the piezoelectric element shown in FIG. [Figure 3] FIG. 2 is an enlarged view of region III in FIG. [Figure 4] FIG. 6 is a cross-sectional view of a piezoelectric element according to a second embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a piezoelectric element according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0018] (First embodiment) A first embodiment will be described with reference to the drawings. The piezoelectric sensor of this embodiment is suitable for use as a microphone, for example.

[0019] As shown in Figures 1 and 2, the piezoelectric sensor includes a support 10 and a vibrating portion 20, and has a rectangular planar shape. The support 10 includes a support substrate 11 having one surface 11a and another surface 11b, and an insulating film 12 formed on 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. In Figure 2, an upper electrode film 63, a first electrode portion 81, a second electrode portion 82, etc., which will be described later, are omitted.

[0020] The vibration section 20 constitutes the sensing section 30, which outputs a pressure detection signal corresponding to pressure such as sound pressure, and is disposed on the support 10. 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 support region 21a disposed on the support 10, and a floating region 21b that is connected to the support region 21a and floats above the recess 10a. Note that 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 substantially rectangular in plan view.

[0021] In this embodiment, the floating region 21b is divided by slits 41 to form four vibration regions 22. In this embodiment, two slits 41 are formed, passing through the center C of the floating region 21b and extending toward opposite corners of the floating region 21b. In other words, the slits 41 extend from each corner of the floating region 21b, which has a rectangular planar shape, toward the center C, and are formed so that the slits 41 intersect at the center C. This separates the floating region 21b into four vibration regions 22, each having a substantially triangular planar shape. Although not particularly limited, in this embodiment, the spacing between the vibration regions 22 (i.e., the average width of the slits 41) is approximately 1 μm. Hereinafter, as shown in FIG. 1, the surface of the vibration region 22 opposite the support 10 will be referred to as one surface 22a, and the surface of the vibration region 22 facing the support 10 will be referred to as the other surface 22b. The one surface 22a and the other surface 22b of the vibration region 22 are parallel to each other.

[0022] As described above, each vibration region 22 is configured by dividing the floating region 21b, and therefore has one end serving as a fixed end supported by the support 10 (i.e., the support region 21a) and the other end serving as a free end, forming a cantilever. In other words, each vibration region 22 is connected to the support region 21a and is supported in a cantilevered manner.

[0023] The vibration section 20 of this embodiment has a configuration including a piezoelectric film 50 and an electrode film 60 connected to the piezoelectric film 50. Specifically, the piezoelectric film 50 has a lower-layer piezoelectric film 51 and an upper-layer piezoelectric film 52 laminated on the lower-layer piezoelectric film 51. The electrode film 60 also has a lower-layer electrode film 61 disposed below the lower-layer piezoelectric film 51, an intermediate electrode film 62 disposed between the lower-layer piezoelectric film 51 and the upper-layer piezoelectric film 52, and an upper-layer electrode film 63 disposed on the upper-layer piezoelectric film 52. In other words, the vibration section 20 has a bimorph structure in which the lower-layer piezoelectric film 51 is sandwiched between the lower-layer electrode film 61 and the intermediate electrode film 62, and the upper-layer piezoelectric film 52 is sandwiched between the intermediate electrode film 62 and the upper-layer electrode film 63.

[0024] Furthermore, the vibration section 20 of this embodiment has an underlayer 70 on which the lower-layer piezoelectric film 51 and the lower-layer electrode film 61 are disposed. That is, the piezoelectric film 50 and the electrode film 60 are disposed on the support 10 via the underlayer 70. The underlayer 70 is not necessarily required, but is provided to facilitate crystal growth when the lower-layer piezoelectric film 51 and the like are formed.

[0025] The lower-layer piezoelectric film 51 and the upper-layer piezoelectric film 52 are made of scandium aluminum nitride (i.e., ScAlN) or the like. The lower-layer electrode film 61, the intermediate electrode film 62, and the upper-layer electrode film 63 are made of molybdenum, copper, platinum, or the like. In this embodiment, the lower-layer electrode film 61, the intermediate electrode film 62, and the upper-layer electrode film 63 are made of molybdenum, which has a lattice constant close to that of the piezoelectric film 50. The base film 70 is made of aluminum nitride or the like.

[0026] In addition, in each vibration region 22 of this embodiment, the fixed end side is defined as a first region R1, and the free end side is defined as a second region R2. The lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 are formed in the first region R1 and the second region R2, respectively. However, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 are separated and insulated from the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the second region R2. The lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 are appropriately extended to the support region 21a.

[0027] In the support region 21a of the vibrating section 20, a first electrode section 81 electrically connected to the lower electrode film 61 and the upper electrode film 63 formed in the first region R1, and a second electrode section 82 electrically connected to the intermediate electrode film 62 formed in the second region R2 are formed. Note that Fig. 1 is a cross-sectional view taken along line II in Fig. 2, and shows different cross sections of the vibrating region 22 on the left side of the paper and the vibrating region 22 on the right side of the paper.

[0028] The first electrode portion 81 includes a first electrode portion wiring portion 81b electrically connected to the lower-layer electrode film 61 and the upper-layer electrode film 63. The second electrode portion 82 includes a second electrode portion wiring portion 82b electrically connected to the intermediate electrode film 62. The specific configurations of the first electrode portion 81 and the second electrode portion 82 will be described later.

[0029] The lower electrode film 61, intermediate electrode film 62, and upper electrode film 63 formed in the second region R2 are not electrically connected to the respective electrode portions 81, 82 and are in a floating state. For this reason, the lower electrode film 61, intermediate electrode film 62, and upper electrode film 63 formed in the second region R2 are not necessarily required, but in this embodiment, they are provided to protect the portions of the lower piezoelectric film 51 and the upper piezoelectric film 52 located in the second region R2.

[0030] The lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 are divided into each vibrating region 22 by the slits 41. That is, the lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 of each vibrating region 22 are not formed so as to straddle each vibrating region 22. The lower electrode film 61, the intermediate electrode film 62, and the upper electrode film 63 formed in the first region R1 of each vibrating region 22 are connected as appropriate via an electrode film (not shown) or the like formed in the support region 21 a.

[0031] Specifically, the sensing unit 30 of this embodiment is configured to output a change in charge in the four vibration regions 22 as one pressure detection signal. That is, the four vibration regions 22 are electrically connected in series. More specifically, each vibration region 22 has a bimorph structure, and the lower-layer electrode films 61, intermediate electrode films 62, and upper-layer electrode films 63 formed in each vibration region 22 are connected in parallel, while the vibration regions 22 are connected in series.

[0032] The above is the basic configuration of the piezoelectric sensor of this embodiment. Next, the configuration of the first electrode portion 81 in the piezoelectric sensor of this embodiment will be specifically described.

[0033] In the support region 21a, the upper-layer piezoelectric film 52 and the lower-layer piezoelectric film 51 have first openings 81a formed therein, which penetrate the upper-layer piezoelectric film 52 and the lower-layer piezoelectric film 51 and expose the lower-layer electrode film 61. A first interlayer insulating film 91 is disposed in the first openings 81a. Specifically, the first interlayer insulating film 91 is disposed so as to fill the first openings 81a. The first interlayer insulating film 91 is also disposed so as to cover a portion of the upper-layer electrode film 63 disposed on the upper-layer piezoelectric film 52 near the first openings 81a. Note that "the first interlayer insulating film 91 covering a portion of the upper-layer electrode film 63" refers to a state in which a portion of the continuously connected upper-layer electrode film 63 is covered by the first interlayer insulating film 91, and the remaining portion of the upper-layer electrode film 63 is exposed through the first interlayer insulating film 91.

[0034] In the first interlayer insulating film 91, a first contact hole 91a exposing the lower electrode film 61 and a second contact hole 91b exposing the upper electrode film 63 are formed.

[0035] The first electrode wiring portion 81b is disposed on the first interlayer insulating film 91, and has a first wiring portion 811 that is electrically connected to the lower electrode film 61 through a first contact hole 91a and electrically connected to the upper electrode film 63 through a second contact hole 91b. The first electrode wiring portion 81b also has a second wiring portion 812 that is disposed on the first wiring portion 811. The second wiring portion 812 is a portion that constitutes a pad portion 101 for connecting to an external circuit.

[0036] In this embodiment, the first wiring portion 811 is made of a metal having a higher ionization tendency than the lower electrode film 61, the upper electrode film 63, and the second wiring portion 812. In this embodiment, the second wiring portion 812 is made of a metal having a lower ionization tendency than the lower electrode film 61 and the upper electrode film 63. In this embodiment, the lower electrode film 61 and the upper electrode film 63 are made of, for example, molybdenum. The second wiring portion 812 is made of gold. The first wiring portion 811 is made of titanium or aluminum.

[0037] Furthermore, in this embodiment, if the area exposed to the outside is defined as the exposed area, the exposed area of the first wiring portion 811 is larger than the exposed area of the second wiring portion 812 and the exposed area of the upper-layer electrode film 63. Note that the exposed area of the upper-layer electrode film 63 here refers to the exposed area of the upper-layer electrode film 63 that is connected to the first wiring portion 811 and is partially covered with the first interlayer insulating film 91.

[0038] 3, the exposed area of the first wiring portion 811 is the sum of an area S11 of a portion of a surface 811a of the first wiring portion 811 opposite the first interlayer insulating film 91 side, which is different from the portion where the second wiring portion 812 is disposed, and an area S12 of the side surface. The exposed area of the second wiring portion 812 is the sum of an area S21 of a surface 812a of the second wiring portion 812 opposite the first wiring portion 811 side, and an area S22 of the side surface. The exposed area of the upper-layer electrode film 63 is the portion exposed from the first interlayer insulating film 91, and is the sum of an area S31 of a surface 63a opposite the upper-layer piezoelectric film 52 side, and an area S32 of the side surface.

[0039] In this embodiment, the second electrode section 82 is configured as follows.

[0040] 1, a second opening 82a is formed in the upper-layer piezoelectric film 52 in the support region 21a, penetrating the upper-layer piezoelectric film 52 to expose the intermediate electrode film 62. A second interlayer insulating film 92 is disposed in the second opening 82a.

[0041] A contact hole 92a exposing the intermediate electrode film 62 is formed in the second interlayer insulating film 92. The second electrode wiring portion 82b is disposed on the second interlayer insulating film 92 and has a first wiring portion 821 electrically connected to the intermediate electrode film 62 through the contact hole 92a. The second electrode wiring portion 82b also has a second wiring portion 822 disposed on the first wiring portion 821. The second wiring portion 822 is a portion that constitutes a pad portion 102 for connecting to an external circuit.

[0042] In this embodiment, the first wiring portion 821 constituting the second electrode wiring portion 82b is made of titanium or aluminum, similar to the first wiring portion 811 of the first electrode wiring portion 81b. The second wiring portion 822 constituting the second electrode wiring portion 82b is made of gold, similar to the second wiring portion 812 constituting the first electrode wiring portion 81b.

[0043] The above is the configuration of the piezoelectric sensor in this embodiment. Such a piezoelectric sensor is manufactured as follows. That is, a support 10 is prepared, and an undercoat film 70, a lower-layer electrode film 61, a lower-layer piezoelectric film 51, an intermediate electrode film 62, an upper-layer piezoelectric film 52, an upper-layer electrode film 63, a first electrode portion 81, a second electrode portion 82, etc. are arranged on the support 10 in this order. Thereafter, a mask made of resist or the like is arranged on the vibration region 22, and after appropriately forming slits 41, recesses 10a, etc., the mask is peeled off, thereby manufacturing the piezoelectric sensor.

[0044] When the mask is peeled off, an electrolytic solution treatment is performed in which the mask is peeled off by immersing it in a peeling solution such as an alkaline solution. At this time, the first wiring portion 811 and the second wiring portion 812 of the first electrode portion wiring portion 81b and the upper layer electrode film 63 form dissimilar metal junctions, and since they are each exposed to the peeling solution, a galvanic current flows, which makes metals with a high ionization tendency more susceptible to corrosion.

[0045] For this reason, in this embodiment, the first wiring portion 811 of the first electrode portion wiring portion 81b is made of a material that has a higher ionization tendency than the upper-layer electrode film 63 and the second wiring portion 812. As a result, in this embodiment, the first wiring portion 811 is more susceptible to corrosion than the upper-layer electrode film 63 and the second wiring portion 812.

[0046] Therefore, corrosion of the upper-layer electrode film 63 can be suppressed, and a decrease in detection accuracy due to an inability to output electric charges from the vibrating region 22 can be suppressed. Furthermore, corrosion of the upper-layer electrode film 63 can be suppressed, and therefore, the floating region 21b (i.e., the vibrating region 22) can be prevented from being out of balance as a whole, causing the floating region 21b to warp. Furthermore, corrosion of the second wiring portion 812 can be suppressed, and a connection failure with an external circuit due to insufficient strength of the wire-bonded pad portion 101 can be suppressed.

[0047] In this embodiment, the first wiring portion 811 is susceptible to corrosion. For this reason, it is preferable that the thickness of the portions of the first wiring portion 811 arranged in the first contact hole 91a and the second contact hole 91b is appropriately adjusted so that the first wiring portion 811 is configured to not break even if corroded. In this case, the first wiring portion 811 is a wiring for connection formed in the support region 21a, and even if it is made thicker, it does not particularly affect the vibration of the vibrating region 22. Furthermore, by identifying the regions that are susceptible to corrosion in this way, design adjustments can be easily made.

[0048] Furthermore, in this embodiment, the second wiring portion 812 of the first electrode portion wiring portion 81b is made of a metal having a lower ionization tendency than the upper-layer electrode film 63. Here, when there are three dissimilar metal junctions, a galvanic current is likely to occur when charge flows from the metal with the lowest ionization tendency to the metal with the highest ionization tendency. Therefore, in this embodiment, a galvanic current particularly easily flows between the second wiring portion 812 and the first wiring portion 811, and the effect on the upper-layer electrode film 63 can be further reduced.

[0049] The second electrode portion 82 is electrically connected to the intermediate electrode film 62, but the intermediate electrode film 62 is not exposed to the outside. Therefore, no galvanic current flows between the second electrode portion 82 and the intermediate electrode film 62. Therefore, the second electrode portion wiring portion 82b does not need to include the second wiring portion 822. However, in this embodiment, since the first electrode portion wiring portion 81b includes the second wiring portion 812, the second electrode portion wiring portion 82b also includes the second wiring portion 812, taking into consideration ease of wire bonding and the manufacturing process. Therefore, even in the second electrode portion 82, there is a possibility that a galvanic current will flow between the first wiring portion 821 and the second wiring portion 822, causing corrosion of the first wiring portion 821. However, in this embodiment, the second wiring portion 822 is used as the pad portion 102, and therefore a decrease in the reliability of the connection between the second electrode portion 82 and an external circuit can be suppressed.

[0050] According to the present embodiment described above, the first wiring portion 811 of the first electrode portion wiring portion 81b and the upper-layer electrode film 63 is made of a material with the highest ionization tendency. Therefore, corrosion of the upper-layer electrode film 63 can be suppressed, and a decrease in detection accuracy due to an inability to output the charge of the vibration region 22 can be suppressed. Furthermore, corrosion of the upper-layer electrode film 63 can be suppressed, and thus, the floating region 21b (i.e., the vibration region 22) can be prevented from being out of balance and warping can be suppressed. Furthermore, corrosion of the second wiring portion 812 can be suppressed, and a connection failure with an external circuit due to insufficient strength of the wire-bonded pad portion 101 can be suppressed. Therefore, a decrease in reliability can be suppressed. Furthermore, with such a piezoelectric element, there is no need to provide a separate protective film to protect the upper-layer electrode film 63, and therefore a decrease in sensitivity can be suppressed.

[0051] (1) In this embodiment, the first wiring portion 811 has a larger area exposed to the outside than the second wiring portion 812. This makes the first wiring portion 811 more susceptible to corrosion, which further suppresses corrosion of the upper electrode film 63 and the second wiring portion 812.

[0052] (2) In this embodiment, the second wiring portion 812 is made of a material that has a lower ionization tendency than the upper electrode film 63. This makes it easier for a galvanic current to flow between the second wiring portion 812 and the first wiring portion 811, and furthermore, makes it possible to suppress corrosion of the upper electrode film 63.

[0053] (3) In this embodiment, the second wiring portion 812 is disposed on the first wiring portion 811. Therefore, compared to when the first wiring portion 811 is disposed on the second wiring portion 812, it is easier to ensure the area of the pad portion 101.

[0054] (Second embodiment) A second embodiment will now be described. This embodiment is different from the first embodiment in that the locations of the second wiring portions 812 and 822 are changed. As the rest of the configuration is the same as the first embodiment, a description thereof will be omitted here.

[0055] In this embodiment, as shown in Fig. 4, the first electrode unit 81 has a first wiring unit 811 and a second wiring unit 812 arranged side by side on the upper-layer piezoelectric film 52. More specifically, the first wiring unit 811 and the second wiring unit 812 are arranged side by side and electrically connected to each other. Note that Fig. 4 shows a case where the first wiring unit 811 and the second wiring unit 812 are arranged completely side by side, but in consideration of manufacturing errors, the second wiring unit 812 may be formed so that a small portion of it remains on the first wiring unit 811.

[0056] In this embodiment, similarly to the first electrode portion 81, the second wiring portion 822 of the second electrode portion 82 is arranged next to the first wiring portion 811 on the upper piezoelectric film 52.

[0057] According to the present embodiment described above, the first wiring portion 811 is made of a material with the highest ionization tendency, and therefore, the same effects as those of the first embodiment can be obtained.

[0058] (1) In this embodiment, the second wiring portion 812 is disposed alongside the first wiring portion 811. As a result, the entire surface 811a of the first wiring portion 811 opposite the first interlayer insulating film 91 is exposed, making it easier to increase the area exposed to the outside. As a result, the first wiring portion 811 can be easily corroded, and furthermore, corrosion of the upper electrode film 63 and the second wiring portion 812 can be suppressed. Furthermore, because the area exposed to the outside of the first wiring portion 811 can be easily increased, even if there is process variation, it is easier to make the exposed area of the first wiring portion 811 larger than the exposed area of the second wiring portion 812.

[0059] (Third embodiment) A third embodiment will now be described. This embodiment is different from the first embodiment in that the positional relationship between the first wiring portion 811 and the second wiring portion 812 is changed. As the rest of the configuration is the same as the first embodiment, a description thereof will be omitted here.

[0060] In this embodiment, as shown in Figure 5, a second wiring portion 812 is arranged on the first interlayer insulating film 91, and the second wiring portion 812 is connected to the lower electrode film 61 through the first contact hole 91a and to the upper electrode film 63 through the second contact hole 91b.

[0061] The first wiring portion 811 is disposed on the second wiring portion 812. In this embodiment, the first wiring portion 811 has a contact hole 811b formed therein, which exposes a portion of the second wiring portion 812. When wire bonding is performed, the portion of the second wiring portion 812 exposed through the contact hole 811b is used as the pad portion 101.

[0062] As with the first electrode portion 81, the first wiring portion 821 is disposed on the second wiring portion 822 for the second electrode portion 82. Then, in a cross section different from that of FIG. 5, a contact hole is formed in the first wiring portion 821 to expose a part of the second wiring portion 822, and when wire bonding is performed, the part of the second wiring portion 822 exposed through the contact hole is used as the pad portion 102.

[0063] According to the present embodiment described above, the first wiring portion 811 is made of a material with the highest ionization tendency, and therefore, the same effects as those of the first embodiment can be obtained.

[0064] (1) In this embodiment, the first wiring portion 811 is disposed on the second wiring portion 812. Therefore, compared to when the second wiring portion 812 is disposed on the first wiring portion 811, the area of the first wiring portion 811 exposed to the outside can be easily increased. Therefore, the first wiring portion 811 can be easily corroded, and furthermore, corrosion of the upper-layer electrode film 63 and the second wiring portion 812 can be suppressed.

[0065] (Other embodiments) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. 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 spirit of the present disclosure.

[0066] For example, in each of the above embodiments, the shape of the slit 41 can be changed as appropriate, and the vibrating region 21 may be supported at both ends.

[0067] Furthermore, in each of the above embodiments, the number of layers of the piezoelectric film 50 and the number of layers of the electrode film 60 can be changed as appropriate.

[0068] In addition, in each of the above embodiments, the first interlayer insulating film 91 does not have to be disposed. For example, in the above first embodiment, the first wiring portion 811 may be disposed in the first opening 81a and electrically connected to the upper-layer electrode film 63 on the upper-layer piezoelectric film 52.

[0069] In each of the above embodiments, the second electrode portion 82 may be composed of only one of the first wiring portion 821 and the second wiring portion 822. [Explanation of symbols]

[0070] 10 Support 20 Vibration unit 21a Support area 21b Floating region 50 Piezoelectric film 60 Electrode membrane 811 1st wiring section 812 2nd wiring section

Claims

1. A piezoelectric element, A support (10); a vibration section (20) disposed on the support, including a piezoelectric film (50) and an electrode film (60) connected to the piezoelectric film, the vibration section (20) having a support region (21a) supported by the support, and a floating region (21b) connected to the support region and floating above the support; an electrode portion (81) disposed in the support region and including a pad portion (101) electrically connected to the electrode film and connected to an external circuit; the electrode film is formed across the floating region and the support region, the electrode portion and the electrode film connected to the electrode portion each have a portion exposed to the outside, The electrode portion has a first wiring portion (811) and a second wiring portion (812) electrically connected to the first wiring portion and constituting the pad portion, The first wiring portion is made of a material having a higher ionization tendency than the second wiring portion and the electrode film.

2. The piezoelectric element according to claim 1 , wherein the first wiring portion has a larger area exposed to the outside than the second wiring portion.

3. 3. The piezoelectric element according to claim 1, wherein the second wiring portion is made of a material having a smaller ionization tendency than the electrode film.

4. The piezoelectric element according to claim 3 , wherein the electrode portion has the second wiring portion disposed on the first wiring portion.

5. The piezoelectric element according to claim 3 , wherein the electrode portion has a portion on the piezoelectric film where the first wiring portion and the second wiring portion are arranged side by side.

6. the electrode portion has the first wiring portion disposed on the second wiring portion, The first wiring portion has a contact hole (811b) formed therein to expose the second wiring portion; The piezoelectric element according to claim 3 , wherein the pad portion is formed by a portion of the second wiring portion exposed from the contact hole.

Images