vibrating plate

Abstract

This invention provides a vibrating plate capable of suppressing the degradation of vibration characteristics. The vibrating plate includes: a vibrating substrate including a base, and a first vibrating arm, a second vibrating arm, and a third vibrating arm extending from the base in the Y-axis direction and arranged in the X-axis direction, wherein, when viewed from the Z-axis direction, the first vibrating arm is disposed between the second and third vibrating arms; a first piezoelectric element disposed across the first vibrating arm and the base, wherein the first vibrating arm is bent and vibrated in the Z-axis direction by extending and contracting in the Y-axis direction, the first piezoelectric element including: a piezoelectric body layer; a lower electrode disposed between the piezoelectric body layer and the vibrating substrate; and an upper electrode overlapping the lower electrode across the piezoelectric body layer, wherein the film thickness of a first portion of the lower electrode and the upper electrode of the first piezoelectric element that overlaps with the boundary of the base and the first vibrating arm is greater than the film thickness of a second portion of the first portion closer to the end of the first vibrating arm.

Description

Technical Field

[0001] This invention relates to vibrating pads. Background Technology

[0002] Patent Document 1 describes a silicon vibrating plate having a base and three vibrating arms extending from the base along the Y-axis. Furthermore, the three vibrating arms are arranged in the X-axis direction, perpendicular to the Y-axis, and each has a piezoelectric element on its upper surface. The piezoelectric element is held between electrodes from above and below. Moreover, by extending and retracting the piezoelectric element under a driving voltage, each vibrating arm vibrates in the Z-axis direction, perpendicular to both the X and Y axes.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2012-160996

[0004] However, in the vibrating plate described in Patent Document 1, when stress exceeding the yield point is applied to the electrodes of the piezoelectric element, the linear relationship between the force applied to the vibrating arm and the deformation of the vibrating arm is disrupted, and the vibration characteristics may be reduced. Summary of the Invention

[0005] The vibrating plate of the present invention, with three mutually orthogonal axes designated as the X-axis, Y-axis, and Z-axis, and the direction along the X-axis as the X-axis direction, the direction along the Y-axis as the Y-axis direction, and the direction along the Z-axis as the Z-axis direction, comprises: a vibrating substrate including a base and a first vibrating arm, a second vibrating arm, and a third vibrating arm extending from the base in the Y-axis direction and arranged in the X-axis direction, wherein, when viewed from the Z-axis direction, the first vibrating arm is disposed between the second vibrating arm and the third vibrating arm; a first piezoelectric element disposed across the first vibrating arm and the base, which, by extending and contracting in the Y-axis direction, causes the first vibrating arm to bend and vibrate in the Z-axis direction; and a second piezoelectric element disposed across the second vibrating arm and the base, which, by extending and contracting in the Y-axis direction, causes the second vibrating arm to bend and vibrate in the Z-axis direction. The first, second, and third piezoelectric elements each include: a piezoelectric layer; a lower electrode disposed between the piezoelectric layer and the base; and an upper electrode that overlaps with the lower electrode across the piezoelectric layer when viewed from above in the Z-axis direction. The first, second, and third piezoelectric elements are configured to flex and vibrate in the Z-axis direction by extending and contracting in the Y-axis direction. Regarding the first, second, and third piezoelectric arms, when the region overlapping the boundary between the base and the vibrating arm is defined as a first portion, and the region closer to the end of the vibrating arm than the first portion is defined as a second portion, the film thickness of the first portion of the lower electrode and the upper electrode of the first piezoelectric element is greater than the film thickness of the second portion.

[0006] The vibrating plate of the present invention, with three mutually orthogonal axes designated as the X-axis, Y-axis, and Z-axis, and the direction along the X-axis as the X-axis direction, the direction along the Y-axis as the Y-axis direction, and the direction along the Z-axis as the Z-axis direction, comprises: a vibrating substrate including a base and a first vibrating arm, a second vibrating arm, and a third vibrating arm extending from the base in the Y-axis direction and arranged in the X-axis direction, wherein, when viewed from the Z-axis direction, the first vibrating arm is disposed between the second vibrating arm and the third vibrating arm; a first piezoelectric element disposed across the first vibrating arm and the base, which, by extending and contracting in the Y-axis direction, causes the first vibrating arm to bend and vibrate in the Z-axis direction; a second piezoelectric element disposed across the second vibrating arm and the base, which, by extending and contracting in the Y-axis direction, causes the second vibrating arm to bend and vibrate in the Z-axis direction; and a third piezoelectric element disposed across the third vibrating arm and the base. The third vibrating arm is subjected to bending vibration in the Z-axis direction by extending and contracting in the Y-axis direction. The first, second, and third piezoelectric elements each include: a piezoelectric layer; a lower electrode disposed between the piezoelectric layer and the vibrating substrate; and an upper electrode that overlaps with the lower electrode across the piezoelectric layer when viewed from above in the Z-axis direction. Regarding the first, second, and third vibrating arms, when the region overlapping the boundary between the base and the vibrating arm is taken as the first part, and the region closer to the end of the vibrating arm than the first part is taken as the second part, the lower electrode and the upper electrode of the first piezoelectric element each include a first electrode film in the first part and a second electrode film in the second part. The first electrode film is connected to the second electrode film, and the first electrode film is made of a material with a higher yield point than the constituent material of the second electrode film. Attached Figure Description

[0007] Figure 1 This is a top view of the MEMS element according to the first embodiment.

[0008] Figure 2 yes Figure 1 Sectional view along line AA in the diagram.

[0009] Figure 3 This is a top view of the vibrating plate of a MEMS element.

[0010] Figure 4 This is a cross-sectional view of the vibrating arm of the vibrating plate.

[0011] Figure 5 It is a diagram used to illustrate the yield point.

[0012] Figure 6 This is a cross-sectional view of the piezoelectric element in the vibrating plate.

[0013] Figure 7 It is a graph showing the change in resonant frequency caused by the magnitude of the driving voltage when T1=T2.

[0014] Figure 8 This is a graph showing the change in resonant frequency caused by the magnitude of the driving voltage when T1>T2.

[0015] Figure 9 This is a cross-sectional view of the piezoelectric element in the vibrating plate.

[0016] Figure 10 This is a cross-sectional view of the vibrating arm of the vibrating plate in the second embodiment.

[0017] Figure 11 This is a cross-sectional view of the piezoelectric element of the vibrating plate in the second embodiment.

[0018] Figure 12 This is a cross-sectional view of the piezoelectric element in the modified example.

[0019] Figure 13 This is a cross-sectional view of the piezoelectric element in the modified example.

[0020] Figure 14 This is a cross-sectional view of the piezoelectric element in the modified example.

[0021] Figure 15 This is a top view showing a modified example of the vibrating plate.

[0022] Label Explanation

[0023] 1…MEMS element, 10…SOI substrate, 11…silicon layer, 12…BOX layer, 13…surface silicon layer, 131…frame, 14…through electrode, 15…through electrode, 20…vibrating plate, 21…vibrating substrate, 210…base, 22…vibrating arm, 22A…first vibrating arm, 22B…second vibrating arm, 22C…third vibrating arm, 23…piezoelectric element, 23A…first piezoelectric element, 23B…second piezoelectric element, 23C…third piezoelectric element, 231…lower electrode, 232…piezoelectric layer, 2 33… Upper electrode, 235a, 235b, 235c, 235d, 235e, 235f… Base-side electrode film, 236a, 236b, 236c, 236d, 236e, 236f… End-side electrode film, 24… Temperature characteristic adjustment section, 24A… Temperature characteristic adjustment film, 24B… Temperature characteristic adjustment film, 24C… Temperature characteristic adjustment film, 5… Cover section, PAD1… Electrode pad, PAD2… Electrode pad, Q1… First part, Q2… Second part, T1… Film thickness, T2… Film thickness. Detailed Implementation

[0024] The vibrating plate of the present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings.

[0025] (First Implementation)

[0026] Figure 1 This is a top view of the MEMS element according to the first embodiment. Figure 2 yes Figure 1 Sectional view along line AA in the diagram. Figure 3 This is a top view of the vibrating plate of a MEMS element. Figure 4 This is a cross-sectional view of the vibrating arm of the vibrating plate. Figure 5 It is a diagram used to illustrate the yield point. Figure 6 This is a cross-sectional view of the piezoelectric element in the vibrating plate. Figure 7 It is a graph showing the change in resonant frequency caused by the magnitude of the driving voltage when T1=T2. Figure 8 This is a graph showing the change in resonant frequency caused by the magnitude of the driving voltage when T1>T2. Figure 9 This is a cross-sectional view of the piezoelectric element in the vibrating plate.

[0027] Furthermore, for ease of explanation, the X-axis, Y-axis, and Z-axis are shown as mutually orthogonal axes in each figure. The direction along the X-axis is referred to as the X-axis direction, the direction along the Y-axis as the Y-axis direction, and the direction along the Z-axis as the Z-axis direction. The X-axis direction is equivalent to the "second direction," and the Y-axis direction is equivalent to the "first direction." The side with the arrow on each axis is referred to as the "positive side," and the side opposite to the arrow is referred to as the "negative side." The positive side of the Z-direction is referred to as "up," and the negative side of the Z-direction is referred to as "down."

[0028] like Figure 1 and Figure 2 As shown, the MEMS device 1 includes: an SOI (Silicon on Insulator) substrate 10 on which a vibrating plate 20 is formed; and a cover portion 5 that provides an hermetically sealed seal between itself and the SOI substrate 10 for the vibrating plate 20. The cover portion 5 is made of monocrystalline silicon or the like and has a recess with an opening on its lower surface. Furthermore, the lower surface of the cover portion 5 is bonded to the upper surface of the SOI substrate 10.

[0029] like Figure 2 As shown, the SOI substrate 10 is a substrate formed by sequentially stacking a silicon layer 11 as a processing layer, a BOX (Buried Oxide) layer 12, and a surface silicon layer 13 as a device layer from the bottom side. For example, the silicon layer 11 and the surface silicon layer 13 are each made of monocrystalline silicon, and the BOX layer 12 is made of silicon oxide (SiO2) layer.

[0030] In addition, such as Figure 1 As shown, a vibrating substrate 21, characteristic of the vibrating plate 20, and a frame-shaped portion 131 surrounding the vibrating substrate 21 are formed on the surface silicon layer 13. Furthermore, a pair of electrode pads PAD1 and PAD2 are disposed on the upper surface of the frame portion 131. Additionally, as... Figure 2 As shown, through electrodes 14 and 15, extending through the SOI substrate 10 in the thickness direction, are formed at positions overlapping with the electrode pads PAD1 and PAD2. Furthermore, through electrode 14 is electrically connected to electrode pad PAD1, and through electrode 15 is electrically connected to electrode pad PAD2. Thus, electrode pads PAD1 and PAD2 are led out from the lower surface of the MEMS element 1 to the outside. Therefore, electrical connection to external devices such as oscillation circuits becomes easy.

[0031] In addition, such as Figure 1 and Figure 2 As shown, the vibrating plate 20 has a vibrating substrate 21 formed on the surface silicon layer 13. That is, the vibrating substrate 21 is formed from a silicon substrate. By forming the vibrating substrate 21 from a silicon substrate, the vibrating substrate 21 can be formed using silicon wafer technology, thus making the processing of the vibrating substrate 21 easier and enabling the vibrating substrate 21 to be formed with high processing precision.

[0032] The vibrating substrate 21 is plate-shaped, having an upper surface and a lower surface that are in a positive-negative relationship. Furthermore, as... Figure 3 As shown, the vibrating substrate 21 has a base 210 and three vibrating arms 22 extending from the base 210, namely a first vibrating arm 22A, a second vibrating arm 22B, and a third vibrating arm 22C. Figure 4 As shown, the base 210 is supported by the underlying silicon layer 11 and BOX layer 12, while the first, second, and third vibrating arms 22A, 22B, and 22C are separated from the BOX layer 12. Therefore, the first, second, and third vibrating arms 22A, 22B, and 22C are cantilever beams that are cantilevered at their base ends by the base 210.

[0033] like Figure 3 As shown, the first, second, and third vibrating arms 22A, 22B, and 22C extend from the base 210 toward the positive side of the Y-axis direction (a first direction) and are arranged side-by-side at equal intervals in the X-axis direction (a second direction). Specifically, the first vibrating arm 22A is located in the center of the arrangement, the second vibrating arm 22B is located on the positive side of the first vibrating arm 22A in the X-axis direction, and the third vibrating arm 22C is located on the negative side of the first vibrating arm 22A in the X-axis direction. That is, the first vibrating arm 22A is located between the second vibrating arm 22B and the third vibrating arm 22C.

[0034] In addition, such as Figure 4As shown, the vibrating plate 20 has a temperature characteristic adjustment section 24 for adjusting the frequency-temperature characteristics of the resonant frequency. The temperature characteristic adjustment section 24 includes: a temperature characteristic adjustment film 24A disposed on the upper surface of the first vibrating arm 22A; a temperature characteristic adjustment film 24B disposed on the upper surface of the second vibrating arm 22B; and a temperature characteristic adjustment film 24C disposed on the upper surface of the third vibrating arm 22C.

[0035] These temperature characteristic adjustment films 24A, 24B, and 24C are composed of silicon oxide (SiO2) layers. Silicon, as the constituent material of the vibrating substrate 21, has a frequency-temperature characteristic where the resonant frequency decreases with increasing temperature. On the other hand, silicon oxide (SiO2), as the constituent material of the temperature characteristic adjustment films 24A, 24B, and 24C, has a frequency-temperature characteristic where the resonant frequency increases with increasing temperature. Therefore, these frequency-temperature characteristics are canceled out, thereby making the frequency-temperature characteristic of the resonant frequency of the composite consisting of the first, second, and third vibrating arms 22A, 22B, and 22C and the temperature characteristic adjustment films 24A, 24B, and 24C nearly flat. For example, by configuring the temperature characteristic adjustment section 24, the variation in the resonant frequency of the vibrating substrate 21 within the temperature range of -25°C to +75°C, which is approximately ±3000 ppm, can be flattened to approximately ±200 ppm to approximately ±500 ppm.

[0036] Furthermore, the structure of the temperature characteristic adjustment films 24A, 24B, and 24C is not particularly limited, and can also be a structure in which other layers such as a zirconium oxide (ZrO2) layer are stacked on a silicon oxide (SiO2) layer. Alternatively, the temperature characteristic adjustment films 24A, 24B, and 24C can also be disposed on the lower surface of the first, second, and third vibrating arms 22A, 22B, and 22C. Additionally, the temperature characteristic adjustment section 24 can be omitted.

[0037] like Figure 3 As shown, the vibrating plate 20 has a driving unit that causes the first, second, and third vibrating arms 22A, 22B, and 22C to bend and vibrate in the Z-axis direction, which is the third direction. The driving unit has: a first piezoelectric element 23A, which is disposed on the upper surface of the first vibrating arm 22A in a manner overlapping the temperature characteristic adjustment film 24A; a second piezoelectric element 23B, which is disposed on the upper surface of the second vibrating arm 22B in a manner overlapping the temperature characteristic adjustment film 24B; and a third piezoelectric element 23C, which is disposed on the upper surface of the third vibrating arm 22C in a manner overlapping the temperature characteristic adjustment film 24C.

[0038] The first, second, and third piezoelectric elements 23A, 23B, and 23C are shorter than the first, second, and third vibrating arms 22A, 22B, and 22C, and are disposed in approximately half of the base end region of the first, second, and third vibrating arms 22A, 22B, and 22C. Furthermore, the first, second, and third piezoelectric elements 23A, 23B, and 23C are arranged across the base 210 and the first, second, and third vibrating arms 22A, 22B, and 22C. These first, second, and third piezoelectric elements 23A, 23B, and 23C extend and retract in the Y-axis direction by the application of a driving voltage. Moreover, through the extension and retraction of the first, second, and third piezoelectric elements 23A, 23B, and 23C, the first, second, and third vibrating arms 22A, 22B, and 22C undergo bending vibration in the Z-axis direction.

[0039] The first, second, and third piezoelectric elements 23A, 23B, and 23C have the same structure as each other, such as Figure 4 As shown, the device includes a lower electrode 231 serving as a first electrode, a piezoelectric layer 232 disposed on the upper surface of the lower electrode 231, and an upper electrode 233 disposed on the upper surface of the piezoelectric layer 232 serving as a second electrode. In other words, the lower electrode 231 and the upper electrode 233 are arranged opposite each other, separated by the piezoelectric layer 232. These lower electrodes 231, piezoelectric layer 232, and upper electrodes 233 are formed using sputtering technology. However, the methods for forming the lower electrodes 231, piezoelectric layer 232, and upper electrodes 233 are not particularly limited.

[0040] Furthermore, the constituent materials of each part of the first, second, and third piezoelectric elements 23A, 23B, and 23C are not particularly limited. However, in this embodiment, the piezoelectric layer 232 is made of aluminum nitride (AlN), and the lower electrode 231 and upper electrode 233 are each made of molybdenum (Mo). In particular, by using molybdenum for the lower electrode 231, the orientation of the aluminum nitride crystals constituting the piezoelectric layer 232 is improved, thereby increasing the piezoelectric constant of the piezoelectric layer 232. Therefore, the electrical energy applied to the first, second, and third piezoelectric elements 23A, 23B, and 23C can be efficiently converted into bending vibrations of the first, second, and third vibrating arms 22A, 22B, and 22C, improving the vibration characteristics of the vibrating plate 20. Additionally, "the lower electrode 231 and upper electrode 233 are made of molybdenum (Mo)" means that molybdenum (Mo) is the main material, but other materials besides molybdenum (Mo) may also be included.

[0041] like Figure 3As shown, the first, second, and third piezoelectric elements 23A, 23B, and 23C are connected to the wiring in such a way that the first vibrating arm 22A located in the center and the second and third vibrating arms 22B and 22C located on both sides of the first vibrating arm 22A bend and vibrate in opposite phases. That is, the first, second, and third piezoelectric elements 23A, 23B, and 23C are connected to the wiring in a way that alternates between a first state in which the second and third vibrating arms 22B and 22C bend and deform upwards while the first vibrating arm 22A bends and deforms downwards, and a second state in which the second and third vibrating arms 22B and 22C bend and deform downwards while the first vibrating arm 22A bends and deforms upwards. Specifically, the lower electrode 231 of the second and third piezoelectric elements 23B and 23C and the upper electrode 233 of the first piezoelectric element 23A are electrically connected to the electrode pad PAD1 via wiring not shown, and the upper electrode 233 of the second and third piezoelectric elements 23B and 23C and the lower electrode 231 of the first piezoelectric element 23A are electrically connected to the electrode pad PAD2 via wiring not shown.

[0042] In this way, by causing adjacent first, second, and third vibrating arms 22A, 22B, and 22C to bend in opposite phases, at least a portion of the vibrations of the first, second, and third vibrating arms 22A, 22B, and 22C are canceled out, effectively suppressing vibration leakage of the vibrating plate 20. Therefore, the Q value is increased, making the vibrating plate 20 more prone to oscillation. The bending vibrations of the first, second, and third vibrating arms 22A, 22B, and 22C are significantly excited at the resonant frequency, resulting in minimal impedance. Consequently, by connecting this MEMS element 1 to an oscillation circuit, an oscillator oscillating at an oscillation frequency determined by the resonant frequency is obtained.

[0043] The overall structure of the vibrating plate 20 has been described above. Next, the structures of the first, second, and third piezoelectric elements 23A, 23B, and 23C will be described in detail. Furthermore, the first, second, and third piezoelectric elements 23A, 23B, and 23C have identical structures. Therefore, they will be referred to as "piezoelectric element 23" below. Similarly, the first, second, and third vibrating arms 22A, 22B, and 22C will also be referred to as "vibrating arm 22" below.

[0044] As described above, by using molybdenum (Mo) to form the lower electrode 231, the orientation of the aluminum nitride crystals constituting the piezoelectric layer 232 is improved, thereby increasing the piezoelectric constant of the piezoelectric layer 232 and improving the vibration characteristics of the vibrating plate 20. However, the yield point of molybdenum (Mo) is much lower than that of silicon (Si), the material constituting the vibrating arm 22, and aluminum nitride (AlN), the material constituting the piezoelectric layer 232. Moreover, this low yield point results in the following disadvantages.

[0045] For example, assuming the thickness of the vibrating arm 22 is 5 μm, the thickness of the lower electrode 231 and the upper electrode 233 is 25 nm, and the thickness of the piezoelectric layer 232 is 200 nm, the yield point of silicon (Si) constituting the vibrating arm 22 is 165 MPa, the yield point of molybdenum (Mo) constituting the lower electrode 231 and the upper electrode 233 is 400 MPa, and the yield point of aluminum nitride (AlN) constituting the piezoelectric layer 232 is 270 MPa. Furthermore, since the thickness of the vibrating arm 22 > the thickness of the piezoelectric layer 232 > the thickness of the lower electrode 231 and the upper electrode 233, the stress applied to the root of the vibrating arm 22 is conversely: vibrating arm 22 < piezoelectric layer 232 < lower electrode 231 and upper electrode 233. Therefore, the lower electrode 231 and the upper electrode 233 are the first to reach the yield point, thus limiting the speed.

[0046] As described above, by energizing the piezoelectric element 23 to extend and retract, the vibrating arm 22 undergoes bending vibration. During this bending vibration, a large stress is applied to the root of the vibrating arm 22, i.e., the boundary between the vibrating arm 22 and the base 210. Furthermore, the greater the driving voltage, the greater the amplitude of the vibrating arm 22, and therefore the greater the stress applied to the root of the vibrating arm 22.

[0047] Here, when the stress applied to the lower electrode 231 and upper electrode 233 during bending vibration is below the yield point of molybdenum (Mo), which is their constituent material, the lower electrode 231 and upper electrode 233 undergo elastic deformation, and therefore the root deforms proportionally to the magnitude of the driving voltage. Thus, the elastic modulus of the vibrating arm 22 does not change. However, when the stress applied to the lower electrode 231 and upper electrode 233 during bending vibration exceeds the yield point, the lower electrode 231 and upper electrode 233 undergo plastic deformation, and the deformation at the root is no longer proportional to the magnitude of the driving voltage. That is, nonlinearity of the material occurs. Therefore, the elastic modulus of the vibrating arm 22 changes, and consequently, the resonant frequency of the vibrating plate 20 changes. Therefore, the driving characteristics of the vibrating plate 20 decrease. Furthermore, the magnitude of the driving voltage varies depending on the user; users with higher driving voltages are more prone to the aforementioned problems.

[0048] To eliminate the aforementioned drawbacks, in this embodiment, the lower electrode 231 and the upper electrode 233 are formed into a structure that makes it difficult to apply pressure exceeding the yield point. Specifically, as... Figure 4 A magnified view of a part Figure 6 As shown, the lower electrode 231 and the upper electrode 233 each have a first portion Q1 that overlaps with the boundary of the base 210 and the vibrating arm 22, and a second portion Q2 that is closer to the end side than the first portion. The first portion Q1 extends from the boundary to both the end side and the base side across the boundary of the base 210 and the vibrating arm 22.

[0049] Furthermore, the film thickness T1 of the first part Q1 is greater than the film thickness T2 of the second part Q2. That is, T1>T2. As described above, when the vibrating arm 22 undergoes bending vibration, a large stress is generated at the root of the vibrating arm 22, i.e., the boundary between the vibrating arm 22 and the base 210. Therefore, by making the film thickness T1 of the first part Q1, which overlaps with this part, greater than the film thickness T2 of the second part Q2, the stress can be effectively dispersed in the first part Q1, making it difficult to apply stress exceeding the yield point to the lower electrode 231 and the upper electrode 233. Therefore, it is less likely to cause changes in the resonant frequency of the vibrating plate 20 due to the nonlinearity of the constituent materials of the lower electrode 231 and the upper electrode 233, and excellent vibration characteristics can be achieved. In addition, although the film thickness T1 of the first part Q1 is not particularly limited, it is preferably, for example, about 100 μm or more and 150 μm or less. As a result, the aforementioned effects become more significant.

[0050] Furthermore, by making the film thickness T2 of the second portion Q2, which overlaps with the portion other than the root of the vibrating arm 22, smaller than the film thickness T1 of the first portion Q1, the overall thickness of the portions of the lower electrode 231 and the upper electrode 233 located on the vibrating arm 22 can be suppressed, thereby minimizing the vibration loss of the vibrating arm 22 caused by the lower electrode 231 and the upper electrode 233. The film thickness T2 of the second portion Q2 is not particularly limited, but is preferably about 20 μm or more and 40 μm or less. This makes the aforementioned effects more significant. As described above, by making T1 > T2, it is less likely for changes in the resonant frequency of the vibrating plate 20 to occur due to the nonlinearity of the constituent material of the upper electrode 233, and the vibration loss of the vibrating arm 22 caused by the lower electrode 231 and the upper electrode 233 can be minimized, thus improving the driving characteristics of the vibrating plate 20.

[0051] here, Figure 7 The diagram shows the deviation in the resonant frequency of the vibrating plate 20 caused by the magnitude of the driving voltage (5mV, 20mV, 40mV) when T1=T2. Figure 8 The diagram shows the deviation in resonant frequency caused by the magnitude of the driving voltage (5mV, 20mV, 40mV) of the vibrating plate 20 when T1 > T2. Figure 7 and Figure 8 It can be seen that when T1=T2, the resonant frequency of the vibrator 20 varies significantly depending on the magnitude of the driving voltage. Conversely, when T1>T2, the resonant frequency of the vibrator 20 remains approximately constant regardless of the magnitude of the driving voltage. That is, the deviation in resonant frequency caused by the magnitude of the driving voltage is smaller when T1>T2 than when T1=T2. Therefore, the aforementioned effect is achieved.

[0052] In particular, in the vibrating plate 20 of this embodiment, all the first, second, and third piezoelectric elements 23A, 23B, and 23C satisfy the relationship T1>T2. Therefore, the above-mentioned effect is more significant, and the driving characteristics of the vibrating plate 20 are improved. However, it is not limited to this. For example, only the first piezoelectric element 23A may satisfy the relationship T1>T2, while the second and third piezoelectric elements 23B and 23C may not satisfy the relationship T1>T2. Compared with the second and third vibrating arms 22B and 22C located on both sides, the first vibrating arm 22A located in the center is more likely to have a larger amplitude, and correspondingly, a greater stress is applied to the root. Therefore, as long as at least the first piezoelectric element 23A satisfies the relationship T1>T2, the above-mentioned effect can be achieved.

[0053] Furthermore, the first portion Q1 extends to the base end of the piezoelectric element 23. With this structure, the first portion Q1 can be made larger, correspondingly reducing the resistance of the lower electrode 231 and the upper electrode 233. Therefore, effective driving of the vibrating plate 20 can be achieved. Additionally, the base end portion of the piezoelectric element 23, i.e., the portion located on the base 210, has no effect on the vibration loss of the vibrating arm 22. Therefore, even if the first portion Q1 extends to the base end of the piezoelectric element 23, it will not lead to a decrease in the vibration characteristics of the vibrating arm 22. However, this is not a limitation; the first portion Q1 may not extend to the base end of the piezoelectric element 23.

[0054] In addition, such as Figure 9 As shown, the film thickness T1 of the first portion Q1 is greater than the film thickness T2 of the second portion Q2 over the entire region in the width direction, i.e., the X-axis direction. Therefore, the volume of the first portion Q1 becomes larger, and stress can be distributed more effectively within the first portion Q1. Consequently, stress exceeding the yield point is more difficult to apply to the lower electrode 231 and the upper electrode 233. Specifically, in this embodiment, the film thickness of the first portion Q1 is constant in the width direction. However, this is not a limitation; in a portion of the width direction of the first portion Q1, the film thickness T1 may be equal to or less than the film thickness T2.

[0055] The MEMS element 1 has been described above. As described above, the MEMS element 1 has a vibrating plate 20 comprising: a vibrating substrate 21 having a base 210, and a first vibrating arm 22A, a second vibrating arm 22B, and a third vibrating arm 22C arranged side-by-side from the base 210 in a Y-axis direction (a first direction) and in an X-axis direction (a second direction perpendicular to the Y-axis direction), wherein the first vibrating arm 22A is located between the second vibrating arm 22B and the third vibrating arm 22C; and a first piezoelectric element 23A disposed across the first vibrating arm 22A and the base 210. By extending and retracting in the Y-axis direction, the first vibrating arm 22A undergoes bending vibration in the Z-axis direction, which is a third direction perpendicular to the X-axis and Y-axis directions. A second piezoelectric element 23B, disposed across the second vibrating arm 22B and the base 210, also undergoes bending vibration in the Z-axis direction by extending and retracting in the Y-axis direction. A third piezoelectric element 23C, disposed across the third vibrating arm 22C and the base 210, also undergoes bending vibration in the Z-axis direction by extending and retracting in the Y-axis direction. Furthermore, the first piezoelectric element 23A, the second piezoelectric element 23B, and the third piezoelectric element 23C each have a piezoelectric layer 232, a lower electrode 231 (serving as a first electrode) disposed between the piezoelectric layer 232 and the vibrating substrate 21, and an upper electrode 233 (serving as a second electrode) disposed opposite the lower electrode 231 across the piezoelectric layer 232. Furthermore, regarding the first piezoelectric element 23A, the film thickness T1 of the first portion Q1 overlapping the boundaries of the base 210 and the first vibrating arm 22A of both the lower electrode 231 and the upper electrode 233 is greater than the film thickness T2 of the second portion Q2 closer to the end of the first vibrating arm 22A than the first portion Q1. With this structure, stress can be effectively dispersed in the first portion Q1, making it less likely to apply stress exceeding the yield point to the lower electrode 231 and the upper electrode 233. Therefore, changes in the resonant frequency of the vibrating plate 20 caused by the nonlinearity of the constituent materials of the lower electrode 231 and the upper electrode 233 are less likely to occur, resulting in a vibrating plate 20 capable of exhibiting excellent vibration characteristics.

[0056] Furthermore, as described above, regarding the second piezoelectric element 23B and the third piezoelectric element 23C, the film thickness T1 of the first portion Q1 is greater than the film thickness T2 of the second portion Q2. With this structure, the second piezoelectric element 23B and the third piezoelectric element 23C can also achieve the same effect as the first piezoelectric element 23A. Therefore, it is less likely for changes in the resonant frequency of the vibrating plate 20 to occur, thus making the vibrating plate 20 capable of exhibiting superior vibration characteristics.

[0057] Furthermore, as mentioned earlier, the film thickness T1 of the first portion Q1 is greater than the film thickness T2 of the second portion Q2 over the entire region in the X-axis direction. With this structure, the volume of the first portion Q1 becomes larger, and correspondingly, stress can be more effectively distributed within the first portion Q1. Therefore, stress exceeding the yield point is less likely to be applied to the lower electrode 231 and the upper electrode 233.

[0058] Furthermore, as described above, the first portion Q1 extends to the base of the first piezoelectric element 23A. This structure reduces the resistance of the lower electrode 231 and the upper electrode 233. Therefore, efficient driving of the vibrating plate 20 can be achieved.

[0059] Furthermore, as previously described, the first vibrating arm 22A, the second vibrating arm 22B, and the third vibrating arm 22C undergo bending vibrations in opposite phases along the Z-axis. With this structure, at least a portion of the vibrations of the first, second, and third vibrating arms 22A, 22B, and 22C are canceled out, effectively suppressing vibration leakage in the vibrating plate 20. Therefore, the Q value is increased, resulting in a vibrating plate 20 that oscillates more easily.

[0060] <Second Implementation>

[0061] Figure 10 This is a cross-sectional view of the vibrating arm of the vibrating plate in the second embodiment. Figure 11 This is a cross-sectional view of the piezoelectric element of the vibrating plate in the second embodiment.

[0062] The MEMS element 1 in this embodiment is the same as that in the first embodiment described above, except that the structures of the lower electrode 231 and the upper electrode 233 of the piezoelectric element 23 are different. In the following description, this embodiment will be described mainly focusing on the differences from the first embodiment described above, and descriptions of the same items will be omitted. In addition, in the figures of this embodiment, the same reference numerals are used to label the same structures as in the above embodiment.

[0063] like Figure 10 and Figure 11As shown, the lower electrode 231 of this embodiment has a base-end side electrode film 235a, which serves as a first electrode film, disposed on the base end side, and an end-end side electrode film 236a, which serves as a second electrode film, disposed on the end side. Similarly, the upper electrode 233 of this embodiment has a base-end side electrode film 235b, which serves as a first electrode film, disposed on the base end side, and an end-end side electrode film 236b, which serves as a second electrode film, disposed on the end side. Furthermore, the base-end side electrode films 235a, 235b and the end-end side electrode films 236a, 236b are respectively disposed across the boundary between the base 210 and the vibration arm 22. The positions where the base-end side electrode films 235a, 235b and the end-end side electrode films 236a, 236b overlap with the boundary between the base 210 and the vibration arm 22 are the first portions Q1. Therefore, at the boundary between the base 210 and the vibrating arm 22, the end portion of the base-side electrode film 235a coincides with the base end portion of the end-side electrode film 236a, and the end portion of the base-side electrode film 235b coincides with the base end portion of the end-side electrode film 236b. Specifically, the base ends of the end-side electrode films 236a and 236b coincide in such a way that they cover the upper side of the end portions of the base-side electrode films 235a and 235b. The base-side electrode films 235a and 235b are connected to the end-side electrode films 236a and 236b. In this structure, the portion of the base-side electrode films 235a and 235b that coincides with the end-side electrode films 236a and 236b constitutes the first part Q1, and the portion of the end-side electrode films 236a and 236b that is closer to the end of the vibrating arm 22 than the first part Q1 constitutes the second part Q2.

[0064] In this embodiment, the end-side electrode films 236a and 236b are each made of molybdenum (Mo). By using molybdenum to form the end-side electrode films 236a and 236b, the orientation of the aluminum nitride crystals constituting the piezoelectric layer 232 is improved, thereby increasing the piezoelectric constant of the piezoelectric layer 232. Therefore, the electrical energy applied to the first, second, and third piezoelectric elements 23A, 23B, and 23C can be efficiently converted into bending vibrations of the first, second, and third vibrating arms 22A, 22B, and 22C, improving the vibration characteristics of the vibrating plate 20. Furthermore, "the end-side electrode films 236a and 236b are made of molybdenum (Mo)" means that molybdenum (Mo) is the main material, but it may also contain materials other than molybdenum (Mo).

[0065] In this embodiment, the base-side electrode films 235a and 235b are made of a material having a higher yield point than the constituent materials of the end-side electrode films 236a and 236b. Specifically, in this embodiment, they are made of titanium nitride (TiN). Thus, by including the base-side electrode films 235a and 235b with high yield points in the first portion Q1, it is less likely to apply stress exceeding the yield point to the lower electrode 231 and the upper electrode 233. Furthermore, "the base-side electrode films 235a and 235b are made of titanium nitride (TiN)" means that titanium nitride (TiN) is the main material, but other materials besides titanium nitride (TiN) may also be included.

[0066] For example, when the thickness of the vibrating arm 22 is 5 μm, the thicknesses of the end-side electrode films 236a and 236b and the base-side electrode films 235a and 235b are 25 nm, and the thickness of the piezoelectric layer 232 is 200 nm, the yield point of molybdenum (Mo) constituting the end-side electrode films 236a and 236b is 400 MPa, and the yield point of titanium nitride (TiN) constituting the base-side electrode films 235a and 235b is 600 MPa. Furthermore, the yield point of aluminum nitride (AlN) constituting the piezoelectric layer 232 is 270 MPa, and the yield point of silicon (Si) constituting the vibrating arm 22 is 165 MPa.

[0067] Alternatively, an oxygen-based ashing treatment can be performed on the surfaces of the base-side electrode films 235a and 235b to form an amorphous layer containing oxygen (O) that readily combines with aluminum. This improves the orientation of the aluminum nitride (AlN) crystals, enabling a similar increase in the piezoelectric constant of the piezoelectric layer 232 as molybdenum (Mo).

[0068] As described above, in the vibrating plate 20 of this embodiment, the first part Q1 has: base-side electrode films 235a and 235b as first electrode films; and end-side electrode films 236a and 236b as second electrode films, which are stacked on the base-side electrode films 235a and 235b and are made of a material with a yield point lower than that of the constituent materials of the base-side electrode films 235a and 235b. According to such a structure, for example, by making the base-side electrode films 235a and 235b from titanium nitride (TiN), it is not easy to apply stress exceeding the yield point to the lower electrode 231 and the upper electrode 233, and by making the end-side electrode films 236a and 236b from molybdenum (Mo), the vibration loss of the vibrating arm 22 can be suppressed to be smaller, and the orientation of the piezoelectric layer 232 can be improved.

[0069] Furthermore, in this embodiment, the film thicknesses of the base-side electrode films 235a and 235b are approximately the same as the film thicknesses of the end-side electrode films 236a and 236b. For example, the film thickness for both is 25 nm. Figure 11As shown, the film thickness T2 of the second part Q2 is the film thickness of the end-side electrode films 236a and 236b, and the film thickness T1 of the first part Q1 is the film thickness formed by the overlap of the end-side electrode films 236a and 236b and the base-side electrode films 235a and 235b. Therefore, the film thickness T1 of the first part Q1 is greater than the film thickness T2 of the second part Q2. That is, T1>T2. As described above, when the vibrating arm 22 undergoes bending vibration, a large stress is generated at the root of the vibrating arm 22, i.e., at the boundary between the vibrating arm 22 and the base 210. Therefore, by making the film thickness T1 of the first part Q1, which overlaps with this part, greater than the film thickness T2 of the second part Q2, the stress can be effectively dispersed in the first part Q1, and it is not easy to apply stress exceeding the yield point to the lower electrode 231 and the upper electrode 233. Therefore, it is not easy to generate changes in the resonant frequency of the vibrating plate 20 caused by the nonlinearity of the constituent materials of the lower electrode 231 and the upper electrode 233, and excellent vibration characteristics can be achieved.

[0070] Similar to the first embodiment, the first portion Q1 can also extend to the base end of the piezoelectric element 23. With this structure, the first portion Q1 can be made larger, correspondingly reducing the resistance of the lower electrode 231 and the upper electrode 233. Therefore, effective driving of the vibrating plate 20 can be achieved. Furthermore, the base end portion of the piezoelectric element 23, i.e., the portion located on the base 210, has no effect on the vibration loss of the vibrating arm 22. Therefore, even if the first portion Q1 extends to the base end of the piezoelectric element 23, it will not lead to a decrease in the vibration characteristics of the vibrating arm 22. However, this is not a limitation; the first portion Q1 may not extend to the base end of the piezoelectric element 23.

[0071] In particular, in the vibrating plate 20 of this embodiment, in all of the first, second, and third piezoelectric elements 23A, 23B, and 23C, the base-side electrode films 235a and 235b are made of a material having a higher yield point than the constituent materials of the end-side electrode films 236a and 236b. Therefore, the aforementioned effect is more significant, and the vibration characteristics of the vibrating plate 20 are improved. However, this is not a limitation; the piezoelectric element in which the base-side electrode films 235a and 235b are made of a material having a higher yield point than the constituent materials of the end-side electrode films 236a and 236b may, for example, be only the first piezoelectric element 23A. Compared to the second and third vibrating arms 22B and 22C located on either side of the first vibrating arm 22A located in the center, the amplitude is more likely to be larger, and correspondingly, greater stress is applied to the root. Therefore, the above-mentioned effects can be achieved as long as at least the base-side electrode films 235a and 235b of the first piezoelectric element 23A are made of a material having a higher yield point than the constituent material of the end-side electrode films 236a and 236b.

[0072] The MEMS element 1 has been described above. As described above, the MEMS element 1 has a vibrating plate 20 comprising: a vibrating substrate 21 having a base 210, and a first vibrating arm 22A, a second vibrating arm 22B, and a third vibrating arm 22C arranged side-by-side from the base 210 in a Y-axis direction (a first direction) and in an X-axis direction (a second direction perpendicular to the Y-axis direction), wherein the first vibrating arm 22A is located between the second vibrating arm 22B and the third vibrating arm 22C; and a first piezoelectric element 23A disposed across the first vibrating arm 22A and the base 210. By extending and retracting in the Y-axis direction, the first vibrating arm 22A undergoes bending vibration in the Z-axis direction, which is a third direction perpendicular to the X-axis and Y-axis directions. A second piezoelectric element 23B, disposed across the second vibrating arm 22B and the base 210, also undergoes bending vibration in the Z-axis direction by extending and retracting in the Y-axis direction. A third piezoelectric element 23C, disposed across the third vibrating arm 22C and the base 210, also undergoes bending vibration in the Z-axis direction by extending and retracting in the Y-axis direction. Furthermore, the first piezoelectric element 23A, the second piezoelectric element 23B, and the third piezoelectric element 23C each have a piezoelectric layer 232, a lower electrode 231 (serving as a first electrode) disposed between the piezoelectric layer 232 and the vibrating substrate 21, and an upper electrode 233 (serving as a second electrode) disposed opposite the lower electrode 231 across the piezoelectric layer 232. Furthermore, the lower electrode 231 and upper electrode 233 of the first piezoelectric element 23A each have base-side electrode films 235a and 235b, which serve as first electrode films, at a first portion Q1 overlapping the boundary of the base 210 and the first vibrating arm 22A, and end-side electrode films 236a and 236b, which serve as second electrode films, at a second portion Q2 closer to the end of the first vibrating arm 22A than the first portion Q1. The base-side electrode films 235a and 235b are connected to the end-side electrode films 236a and 236b, and the base-side electrode films 235a and 235b are made of a material with a higher yield point than the constituent materials of the end-side electrode films 236a and 236b. Therefore, it is less likely for the resonant frequency of the vibrating plate 20 to change due to the nonlinearity of the constituent materials of the lower electrode 231 and the upper electrode 233, and the vibrating plate 20 can exhibit excellent vibration characteristics.

[0073] Furthermore, as previously described, the base-side electrode films 235a and 235b are formed across the boundary between the base 210 and the first vibrating arm 22A, and overlap with the end-side electrode films 236a and 236b at the first portion Q1. According to this structure, the film thickness T1 of the first portion Q1 is greater than the film thickness T2 of the second portion Q2. Therefore, stress can be effectively dispersed at the first portion Q1, and stress exceeding the yield point is less likely to be applied to the lower electrode 231 and the upper electrode 233.

[0074] Furthermore, as described above, regarding the second piezoelectric element 23B and the third piezoelectric element 23C, the base-side electrode films 235a and 235b are also made of a material with a higher yield point than the constituent materials of the end-side electrode films 236a and 236b. With this structure, the second piezoelectric element 23B and the third piezoelectric element 23C can also achieve the same effect as the first piezoelectric element 23A. Therefore, it is less likely for changes in the resonant frequency of the vibrating plate 20 to occur, and the vibrating plate 20 can exhibit superior vibration characteristics.

[0075] Furthermore, as described above, the base-side electrode films 235a and 235b are titanium nitride (TiN), and the end-side electrode films 236a and 236b are molybdenum (Mo). This structure improves the orientation of the aluminum nitride (AlN) film deposited on the molybdenum (Mo). Therefore, the electromechanical coupling coefficient between aluminum nitride (AlN) and molybdenum (Mo) can be increased, resulting in less vibration loss.

[0076] Furthermore, as previously described, the first vibrating arm 22A, the second vibrating arm 22B, and the third vibrating arm 22C undergo bending vibrations in opposite phases along the Z-axis. According to this structure, at least a portion of the vibrations of the first, second, and third vibrating arms 22A, 22B, and 22C are canceled out, effectively suppressing vibration leakage of the vibrating plate 20. Therefore, the vibrating plate 20 can improve its Q value and oscillate more easily.

[0077] <Modifications of the Second Embodiment>

[0078] In the second embodiment, the thickness of the end-side electrode films 236a and 236b made of molybdenum (Mo) is described as being approximately the same as the thickness of the base-side electrode films 235a and 235b made of titanium nitride (TiN), but this is not a particular limitation. For example, as Figure 12 As shown, the thickness of the end-side electrode films 236a and 236b can also be smaller than the thickness of the base-side electrode films 235a and 235b. Furthermore, the thickness of the end-side electrode films 236a and 236b is preferably as thin as possible, as long as it effectively improves the orientation of aluminum nitride crystallization. With this structure, the vibration loss of the vibrating arm 22 caused by the lower electrode 231 and the upper electrode 233 can be minimized.

[0079] Furthermore, it is stated that the base ends of the end-side electrode films 236a and 236b overlap in such a way that they cover the upper side of the end portions of the base-side electrode films 235a and 235b, but this is not particularly limited to this. For example, as Figure 13 As shown, the ends of the base-side electrode films 235c and 235d can also overlap to cover the upper side of the base ends of the end-side electrode films 236c and 236d. Even with this structure, the same effect as described above can be achieved.

[0080] Furthermore, the case where the base-side electrode films 235a and 235b overlap with the end-side electrode films 236a and 236b at the first portion Q1 has been described, but it is not particularly limited to this. For example, as Figure 14 As shown, the base-side electrode films 235e and 235f and the end-side electrode films 236e and 236f can also be connected in the Y-axis direction without overlapping. In this case, it is preferable that the base-side electrode films 235e and 235f are arranged across the boundary between the base 210 and the vibrating arm 22. By adopting such a structure, the film thickness of the upper electrode 233 and the lower electrode 231 can be made uniform in the Y-axis direction. In addition, the thickness of the piezoelectric layer 232 can be made uniform in the Y-axis direction. As a result, the first, second, and third vibrating arms 22A, 22B, and 22C can vibrate equally on both the +Z and -Z sides. As a result, the vibrating plate 20 can improve its Q value and oscillate more easily.

[0081] The vibrating plate 20 of the present invention has been described above with reference to the illustrated embodiments, but the present invention is not limited thereto. The structure of each part can be replaced with any structure having the same function. In addition, other arbitrary structures can be added to the present invention.

[0082] For example, although the vibrating plate 20 has three vibrating arms in the aforementioned embodiment, the number of vibrating arms is not limited to this. For example, as Figure 15 As shown, it can have 4 vibrating arms or more than 5 vibrating arms. Additionally, in Figure 15 In the structure shown, the two arms in the center are the first vibrating arms 22A, and the arms on either side are the second vibrating arms 22B and the third vibrating arms 22C. However, as long as the second and third vibrating arms 22B and 22C are located on either side of the first vibrating arm 22A, it is not specifically limited which vibrating arm corresponds to which of the first, second, and third vibrating arms 22A, 22B, and 22C.

Claims

1. A vibrating plate, characterized in that, Let the three mutually orthogonal axes be the X-axis, Y-axis, and Z-axis, and let the direction along the X-axis be the X-axis direction, the direction along the Y-axis be the Y-axis direction, and the direction along the Z-axis be the Z-axis direction. The vibrating plate includes: A vibrating substrate includes a base and a first vibrating arm, a second vibrating arm, and a third vibrating arm extending from the base toward the Y-axis and arranged in the X-axis direction. When viewed from the Z-axis direction, the first vibrating arm is disposed between the second vibrating arm and the third vibrating arm. A first piezoelectric element, which is configured across the first vibrating arm and the base, causes the first vibrating arm to bend and vibrate in the Z-axis direction by extending and retracting in the Y-axis direction; A second piezoelectric element, configured across the second vibrating arm and the base, causes the second vibrating arm to bend and vibrate in the Z-axis direction by extending and retracting in the Y-axis direction; and A third piezoelectric element, configured across the third vibrating arm and the base, causes the third vibrating arm to bend and vibrate in the Z-axis direction by extending and retracting in the Y-axis direction. The first piezoelectric element, the second piezoelectric element, and the third piezoelectric element each comprise: piezoelectric layer; The lower electrode is disposed between the piezoelectric layer and the vibrating substrate; and When viewed from above along the Z-axis, the upper electrode overlaps with the lower electrode through the piezoelectric layer. Regarding the first vibrating arm, the second vibrating arm, and the third vibrating arm, when the region overlapping with the boundary of the base and the vibrating arm is defined as the first part, and the region closer to the end of the vibrating arm than the first part is defined as the second part, The film thickness of the first portion of the lower electrode and the upper electrode of the first piezoelectric element is greater than the film thickness of the second portion.

2. The vibrating plate according to claim 1, wherein, Regarding the second piezoelectric element and the third piezoelectric element The thickness of the first part is greater than the thickness of the second part.

3. The vibrating plate according to claim 1, wherein, In the entire region along the X-axis, the film thickness of the first portion is greater than that of the second portion.

4. The vibrating plate according to claim 1, wherein, The first portion extends to the base of the first piezoelectric element.

5. The vibrating plate according to claim 1, wherein, The first part includes: First electrode film; and The second electrode film, which is stacked on top of the first electrode film, is made of a material with a lower yield point than the constituent material of the first electrode film.

6. The vibrating plate according to claim 1, wherein, The first vibrating arm, the second vibrating arm, and the third vibrating arm perform bending vibrations in opposite phases in the Z-axis direction.

7. A vibrating plate, characterized in that, Let the three mutually orthogonal axes be the X-axis, Y-axis, and Z-axis, and let the direction along the X-axis be the X-axis direction, the direction along the Y-axis be the Y-axis direction, and the direction along the Z-axis be the Z-axis direction. The vibrating plate includes: A vibrating substrate includes a base and a first vibrating arm, a second vibrating arm, and a third vibrating arm extending from the base toward the Y-axis and arranged in the X-axis direction. When viewed from the Z-axis direction, the first vibrating arm is disposed between the second vibrating arm and the third vibrating arm. A first piezoelectric element, which is configured across the first vibrating arm and the base, causes the first vibrating arm to bend and vibrate in the Z-axis direction by extending and retracting in the Y-axis direction; A second piezoelectric element, configured across the second vibrating arm and the base, causes the second vibrating arm to bend and vibrate in the Z-axis direction by extending and retracting in the Y-axis direction; and A third piezoelectric element, configured across the third vibrating arm and the base, causes the third vibrating arm to bend and vibrate in the Z-axis direction by extending and retracting in the Y-axis direction. The first piezoelectric element, the second piezoelectric element, and the third piezoelectric element each comprise: piezoelectric layer; The lower electrode is disposed between the piezoelectric layer and the vibrating substrate; and When viewed from above along the Z-axis, the upper electrode overlaps with the lower electrode through the piezoelectric layer. Regarding the first vibrating arm, the second vibrating arm, and the third vibrating arm, when the region overlapping with the boundary of the base and the vibrating arm is defined as the first part, and the region closer to the end of the vibrating arm than the first part is defined as the second part, The lower electrode and the upper electrode of the first piezoelectric element each include a first electrode film at the first portion and a second electrode film at the second portion. The first electrode film is connected to the second electrode film. The first electrode film is made of a material with a higher yield point than the material constituting the second electrode film.

8. The vibrating plate according to claim 7, wherein, Regarding the first vibrating arm The first electrode film is disposed across the boundary between the base and the vibrating arm. The first electrode film overlaps with the second electrode film at the first portion.

9. The vibrating plate according to claim 7, wherein, Regarding the second piezoelectric element and the third piezoelectric element The first electrode film is made of a material with a higher yield point than the material constituting the second electrode film.

10. The vibrating plate according to claim 7, wherein, The first electrode film is titanium nitride, and the second electrode film is molybdenum.

11. The vibrating plate according to claim 7, wherein, The first vibrating arm, the second vibrating arm, and the third vibrating arm perform bending vibrations in opposite phases in the Z-axis direction.

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