Piezoelectric element and method for manufacturing piezoelectric element

Abstract

To improve k2eff in a piezoelectric device.SOLUTION: A piezoelectric element according to an aspect includes a structure in which a first electrode layer, a second electrode layer, a first layer that is positioned between the first electrode layer and the second electrode layer and has piezoelectricity, and a second layer that is provided between the first layer and the second layer via the first electrode layer, has the same main component as a main component of the first layer, and has lower piezoelectricity than the first layer are laminated, and a substrate that supports an edge of the structure.SELECTED DRAWING: Figure 1b

Description

[Technical Field]

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

[0002] Fingerprint sensors used in mobile phones and medical ultrasound devices use ultrasonic transducers, a type of ultrasonic element. A well-known ultrasonic transducer is the piezoelectric micromachined ultrasonic transducer (pMUT), which uses a piezoelectric material. A pMUT is a piezoelectric ultrasonic transducer created using MEMS (Micro Electro Mechanical Systems) technology. In a pMUT, a layered vibrating body, in which a piezoelectric material is sandwiched between electrodes, is formed on a substrate such as SOI (Silicon on Insulator). A cavity is provided under the vibrating body in the substrate to facilitate vibration of the vibrating body.

[0003] When ultrasound is applied to a pMUT, a flexural vibration is induced in the vibrating element, generating a voltage due to the piezoelectric effect. Furthermore, when voltage is applied to the pMUT, deformation of the piezoelectric element occurs due to the inverse piezoelectric effect, inducing a flexural vibration in the vibrating element, which then emits ultrasound. In other words, pMUTs can transmit and receive ultrasound using the piezoelectric and inverse piezoelectric effects, and are used in imaging devices such as fingerprint authentication and medical ultrasound.

[0004] Patent Document 1 discloses a pMUT having a drive structure on a vibrating membrane. The drive structure has a piezoelectric layer sandwiched between an upper electrode and a vibrating membrane, and the center of the drive structure is formed in the center of a cavity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2020 / 0194658 Summary of the Invention [Problem to be solved by the invention]

[0006] In ultrasonic transducers, the electromechanical coupling coefficient (k 2 eff In addition to ultrasonic transducers, various piezoelectric elements, including filter elements such as FBAR (Film Bulk Acoustic Resonator), require improvements in k 2 eff Improvement is required.

[0007] In view of the above circumstances, the present invention provides a piezoelectric element having a k 2 eff The purpose is to improve. [Means for solving the problem]

[0008] In order to solve the above problem, a piezoelectric element according to one embodiment of the present invention comprises a structure in which a first electrode layer, a second electrode layer, a first layer located between the first electrode layer and the second electrode layer and having piezoelectricity, and a second layer provided between the first layer and the second electrode layer via the first electrode layer, having the same main component as the first layer but having lower piezoelectricity than the first layer, and a substrate supporting the edges of the structure.

[0009] In the piezoelectric element according to one aspect of the present invention, the second layer has almost no piezoelectricity. In the piezoelectric element according to one aspect of the present invention, the second layer is a layer whose main component is amorphous. In the piezoelectric element according to one aspect of the present invention, the second layer is a layer in which the main component contains an additive.

[0010] In one embodiment of the piezoelectric element of the present invention, the first layer and the second layer are made of a material whose main component is one of AlN, PZT (lead zirconate titanate), KNN (potassium sodium niobate), BiFeO3, BaTiO3, LiNbO3, LiTaO3, ZnO, and pVDF (polyvinylidene fluoride). In the piezoelectric element according to one aspect of the present invention, the first layer and the second layer are made of a material containing any one of PZT, KNN, BiFeO3, BaTiO3, LiNbO3, and LiTaO3 as a main component.

[0011] A piezoelectric element according to one aspect of the present invention further comprises a stopper layer on the substrate side of the structure, which stops the progress of a process that unsupports the portions of the structure other than the edge. In a piezoelectric element according to one aspect of the present invention, a plurality of the structures are arranged in a direction in which the layers of the structures extend.

[0012] In addition, in order to solve the above problem, a method for manufacturing a piezoelectric element according to one embodiment of the present invention is a method for manufacturing a piezoelectric element comprising a structure in which a second layer, a first electrode layer, a first layer and a second electrode layer are stacked in this order, and a substrate supporting the edges of the structure, and includes the steps of forming the first electrode layer, forming the second electrode layer, forming the first layer having piezoelectricity, and forming the second layer having the same main component as the first layer but lower piezoelectricity than the first layer.

[0013] In the method for manufacturing a piezoelectric element according to one aspect of the present invention, the step of forming the second layer is performed at a temperature lower than the temperature at which a main component of the second layer crystallizes. [Effects of the Invention]

[0014] According to the present invention, the k 2 eff can be improved. [Brief explanation of the drawings]

[0015] [Figure 1a]1 is a top view showing an embodiment of a piezoelectric element according to the present invention. [Figure 1b] 1 is a cross-sectional view showing an embodiment of a piezoelectric element according to the present invention. [Figure 2a] FIG. 10 is a top view showing a modified example of the pMUT. [Figure 2b] FIG. 10 is a cross-sectional view showing a modified example of the pMUT. [Figure 3] FIG. 10 is a diagram showing another modified example of the pMUT. [Figure 4] FIG. 1 is a diagram showing a model for simulation of a pMUT. [Figure 5] 10 is a graph showing a simulation result when the main component is AlN. [Figure 6] 10 is a graph showing a simulation result when the main component is ZnO. [Figure 7a] 1 is a cross-sectional view showing a first step in a method for manufacturing a pMUT. [Figure 7b] FIG. 4 is a cross-sectional view showing a second step in the method for manufacturing the pMUT. [Figure 7c] FIG. 10 is a cross-sectional view showing a third step in the method for manufacturing the pMUT. [Figure 8a] FIG. 10 is a cross-sectional view showing a fourth step in the method for manufacturing a pMUT. [Figure 8b] FIG. 10 is a cross-sectional view showing a fifth step in the method for manufacturing a pMUT. [Figure 8c] FIG. 10 is a cross-sectional view showing a sixth step in the method for manufacturing a pMUT. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (such as usage conditions and usage environment).

[0017] The technical scope of the present invention is defined by the claims and is not limited by the individual embodiments described below. The drawings used in the following description may differ in scale and shape from the actual structure to make each configuration easier to understand. The correspondence between the drawings may also differ in some places to simplify the description. Components shown in previously described drawings may be referenced as appropriate in the description of subsequent drawings.

[0018] <Configuration of ultrasonic element> 1a and 1b are diagrams showing an embodiment of a piezoelectric element according to the present invention, where Fig. 1a shows a top view and Fig. 1b shows a cross-sectional view taken along line AA in Fig. 1a. A pMUT (Piezoelectric Micromachined Ultrasonic Transducer) 100 corresponds to one embodiment of the piezoelectric element according to the present invention. The pMUT 100 of this embodiment includes an upper electrode 101, a piezoelectric layer 102, a lower electrode 103, a low-piezoelectric layer 104, a substrate 105, and a stopper layer 106. In describing the layered structure, the side closer to the substrate 105 may be referred to as "bottom" and the side farther from it as "top," regardless of the direction of gravity.

[0019] The vibrating body 110 corresponds to an example of a structure according to the present invention. The vibrating body 110 includes a structure in which at least an upper electrode 101, a piezoelectric layer 102, a lower electrode 103, and a low-piezoelectric layer 104 are laminated. A cylindrical cavity 51 is provided in the substrate 105. The substrate 105 supports an edge portion 111 of the vibrating body 110. A center portion 112 of the vibrating body 110 is located on the cavity 51, and the front and back surfaces of the vibrating body 110 are unsupported. Therefore, the vibrating body 110 has a structure in which the center portion 112 is likely to bend and vibrate. Examples of materials that can be used for the substrate 105 include Si, SiC, sapphire, mica, h-BN, glass, and SUS (stainless steel). When SiC is used as the material for the substrate 105, it is suitable for film formation by epitaxial growth.

[0020] The upper electrode 101 and the lower electrode 103 are provided on the front and back surfaces of the piezoelectric layer 102, respectively. The upper electrode 101 and the lower electrode 103 have shapes that extend along the surface of the piezoelectric layer 102. The lower electrode 103 corresponds to an example of the first electrode layer according to the present invention, and the upper electrode 101 corresponds to an example of the second electrode layer according to the present invention. Alternatively, the lower electrode 103 may correspond to an example of the second electrode layer according to the present invention, and the upper electrode 101 may correspond to an example of the second electrode layer according to the present invention.

[0021] The upper electrode 101 extends, for example, in a circular shape and is provided, for example, in the center of the cavity 51 of the substrate 105 when viewed from above. The lower electrode 103 extends, for example, over the entire substrate 105 when viewed from above. Materials used for the upper electrode 101 and the lower electrode 103 include, for example, Ru, Mo, Au, Ti, Pt, Al, Cu, Cr, Ag, Pd, and Ni. The upper electrode 101 and the lower electrode 103 may also be layered electrodes in which multiple metal layers are stacked.

[0022] The upper electrode 101 is electrically connected to the peripheral circuitry of the pMUT 100 via wiring 11 and pad 12, and the lower electrode 103 is electrically connected to the peripheral circuitry via pad 31. The upper electrode 101 and the lower electrode 103 apply a voltage to the piezoelectric layer 102 or output a voltage signal generated in the piezoelectric layer 102 to the peripheral circuitry.

[0023] The piezoelectric layer 102 is located between the upper electrode 101 and the lower electrode 103, and in this embodiment, for example, the piezoelectric layer 102 is sandwiched between the upper electrode 101 and the lower electrode 103. The piezoelectric layer 102 corresponds to an example of the first layer referred to in the present invention. The piezoelectric layer 102 is a layer whose main component is a piezoelectric material, and is made of a material whose main component is, for example, any of AlN, PZT (lead zirconate titanate), KNN (potassium sodium niobate), BiFeO3, BaTiO3, LiNbO3, LiTaO3, ZnO, and pVDF (polyvinylidene fluoride). When AlN is the main component of the material of the piezoelectric layer 102, Sc, Mg, or Hf may be added.

[0024] As the material for the piezoelectric layer 102, materials primarily composed of PZT, KNN, BiFeO3, BaTiO3, LiNbO3, and LiTaO3 are particularly preferred because they have a high piezoelectric effect. Furthermore, materials primarily composed of AlN are easy to form and process, have high insulation properties, allow for the application of large voltages, have a high elastic modulus, and a high mechanical quality factor Qm. Therefore, when AlN is used as the primary component, the displacement speed of the vibrating body 110 is high, enabling the pMUT 100, other ultrasonic elements, or piezoelectric elements to handle high sound pressures and high frequencies.

[0025] The low piezoelectric layer 104 is a layer containing the same material as the piezoelectric layer 102 as its main component, and extends along the lower electrode 103. The low piezoelectric layer 104 corresponds to an example of the second layer referred to in the present invention, and has lower piezoelectricity than the piezoelectric layer 102. In particular, the low piezoelectric layer 104 of this embodiment has such low piezoelectricity that it is almost non-existent. The lower electrode 103 is located between the piezoelectric layer 102 and the low piezoelectric layer 104, and in this embodiment, as an example, the lower electrode 103 is sandwiched between the piezoelectric layer 102 and the low piezoelectric layer 104.

[0026] The main component of the material of the low piezoelectric layer 104 is the same as the main component of the material of the piezoelectric layer 102. However, while the material of the piezoelectric layer 102 is a piezoelectric material, the material of the low piezoelectric layer 104 is a material with reduced piezoelectricity. Specifically, the material of the low piezoelectric layer 104 is a crystal made by adding an additive to the same material as the main component of the piezoelectric layer 102, or is made by making the same material as the main component of the piezoelectric layer 102 amorphous and reducing the piezoelectricity.

[0027] One example of reducing the piezoelectricity is doping AlN with boron as an additive. When Al in AlN is replaced with boron, boron forms more covalent bonds with N than with Al, reducing the piezoelectric bond. By adjusting the amount of boron doping, the low piezoelectric layer 104 becomes a layer with almost no piezoelectricity. The additive for reducing the piezoelectricity varies depending on the piezoelectric material and is not limited to the above-mentioned specific combinations.

[0028] Another example of reducing the piezoelectricity is to make the material of the low piezoelectric layer 104 amorphous through a manufacturing process described below. By making the material amorphous, the low piezoelectric layer 104 becomes a layer that has almost no piezoelectricity. However, even if the temperature or film formation time of the piezoelectric element is controlled during the process, some crystallinity may remain. In this case, the low piezoelectric layer 104 may exhibit low piezoelectricity, but the piezoelectricity will be significantly lower than that of the piezoelectric layer 102.

[0029] As explained above, making the low piezoelectric layer 104 have almost no piezoelectricity does not necessarily mean that it does not exhibit any piezoelectricity at all. In other words, it does not necessarily mean that polarization does not occur and no charge transfer occurs when a strain is applied to the piezoelectric element, nor does it necessarily mean that no strain occurs when an electric field is applied to the piezoelectric element.

[0030] Since the piezoelectric layer 102 and the low piezoelectric layer 104 are made of the same main component material, the Young's modulus of the piezoelectric layer 102 and the Young's modulus of the low piezoelectric layer 104 are close to each other, and the electromechanical coupling coefficient (k 2 eff ) is improved. In addition, since the piezoelectricity of the low piezoelectric layer 104 is lower than that of the piezoelectric layer 102, spurious can be reduced and vibration characteristics can be improved. Therefore, the pMUT 100 can convert between ultrasonic waves and electrical signals with high conversion efficiency.

[0031] The stopper layer 106 is a layer extending between the vibrating body 110 and the substrate 105, and specifically made of, for example, SiO2, Si3N4, SiN, Al2O3, Ta2O5, TiO2, ZrO2, or HfO2. The stopper layer 106 protects the vibrating body 110 by stopping the progress of a processing step for forming a cavity 51 in the substrate 105, as will be described later.

[0032] <Modification> Figures 2a and 2b show modified examples of pMUTs, with Figure 2a showing a top view and Figure 2b showing a cross-sectional view taken along line BB in Figure 2a. The pMUT 150 of the modified example includes a plurality of vibrating bodies 110 similar to those of the above embodiment on a substrate 105. The plurality of vibrating bodies 110 are arranged, for example, in a matrix pattern in the direction in which the layers in the layer structure of the vibrating bodies 110 extend. The substrate 105 is provided with a cavity 51 corresponding to each vibrating body 110. The pMUT 150 of the modified example functions as an array element, and the plurality of vibrating bodies 110 vibrate in coordination or individually.

[0033] FIG. 3 shows another modified example of the pMUT, and shows a cross-sectional view similar to FIG. 1b. The pMUT 160 of the modified example shown in FIG. 3 has a structure in which a vibrating body 110 is supported on a substrate 105, as in the above embodiment, and a stopper layer 106 is provided between the substrate 105 and the vibrating body 110.

[0034] However, in the modified pMUT 160, the layered structure of the vibrating body 110 is different from that of the above embodiment. That is, the low-piezoelectric layer 104 extends along the upper electrode 101, and the upper electrode 101 is located between the piezoelectric layer 102 and the low-piezoelectric layer 104. Therefore, in the modified pMUT 160, the upper electrode 101 corresponds to an example of the first electrode layer according to the present invention.

[0035] Although the position of the low-piezoelectric layer 104 is different from that of the above embodiment, the electromechanical coupling coefficient (k 2 eff ) is improved, and vibration characteristics such as reduced spurious are improved. Therefore, the pMUT160 of the modified example can convert between ultrasonic waves and electrical signals with high conversion efficiency.

[0036] <Simulation> FIG. 4 is a diagram showing a model for simulating a pMUT. 4 is an analytical model using the finite element method, with the same basic configuration as the pMUT 100 of the above embodiment set as a condition. In the model 200, a vibrating body 110 is supported on a substrate 105, and a stopper layer 106 is provided between the substrate 105 and the vibrating body 110. The vibrating body 110 has a layered structure in which, from the substrate 105 side, a low-voltage piezoelectric layer 104, a lower electrode 103, a piezoelectric layer 102, and an upper electrode 101 are layered.

[0037] In the model 200, a layered electrode is set as the upper electrode 101. Specifically, the upper electrode 101 includes a Ru layer 202 stacked on the piezoelectric layer 102 and a Cr layer 201 stacked on the Ru layer 202. Similarly, the lower electrode 103 is also set as a layered electrode, and includes a Cr layer 204 stacked on the stopper layer 106 and a Ru layer 203 stacked on the Cr layer 204.

[0038] In the model 200, the material of the substrate 105 is set to Si, and the material of the stopper layer 106 is set to SiO2. The thickness of each layer in the vibrating body 110 of the model 200 is set to 20 nm for the Cr layers 201 and 204 of the upper electrode 101 and the lower electrode 103, and 100 nm for the Ru layers 202 and 203. The piezoelectric layer 102 is set to 1000 nm, and the low-piezoelectric layer 104 has a variety of thicknesses. The main components of the material of the piezoelectric layer 102 and the low piezoelectric layer 104 are set to be AlN and ZnO.

[0039] Fig. 5 is a graph showing the simulation results when the main component is AlN, and Fig. 6 is a graph showing the simulation results when the main component is ZnO. The horizontal axis of Fig. 5 and Fig. 6 represents the ratio of the Young's modulus of the piezoelectric layer 102 to that of the low piezoelectric layer 104, and the vertical axis represents the difference value fa-fr between the antiresonant frequency fa and the resonant frequency fr.

[0040] This simulation calculated the impedance when an AC voltage of 1 V amplitude was applied between the upper electrode 101 and the lower electrode 103. Frequencies in 2 Hz increments were used as the AC voltage frequency, and the frequency at which the impedance was smallest was taken as the resonance frequency fr, and the frequency at which the impedance was largest was taken as the anti-resonance frequency fa. The difference value fa-fr between the anti-resonance frequency fa and the resonance frequency fr is the electromechanical coupling coefficient (k 2 eff ) is a good indicator of

[0041] 5 and 6 show how the difference value fa-fr between the anti-resonance frequency fa and the resonant frequency fr changes when the thickness of the low piezoelectric layer 104 is changed to change the Young's modulus of the low piezoelectric layer 104. On the horizontal axis of Figures 5 and 6, the Young's modulus (elastic modulus) of the low piezoelectric layer 104 is normalized by the Young's modulus of the piezoelectric layer 102. On the vertical axis of Figures 5 and 6, the difference value fa-fr is normalized by the difference value when the Young's modulus ratio is "1".

[0042] From the graphs of FIGS. 5 and 6, the difference value fa-fr becomes the highest when the Young's modulus of the piezoelectric layer 102 and the low-piezoelectric layer 104 is approximately equal, and a high electromechanical coupling constant (k 2 eff ) can be obtained. In other words, whether the main component is AlN or ZnO, the piezoelectric layer 102 and the low piezoelectric layer 104 share the same main component, so that the Young's moduli of the piezoelectric layer 102 and the low piezoelectric layer 104 are close to each other, and a high electromechanical coupling constant (k 2 eff ) will be obtained.

[0043] <Manufacturing method> An example of a method for manufacturing a pMUT will be described below. 7a, 7b, 7c, 8a, 8b, and 8c are cross-sectional views showing a method for manufacturing a pMUT.

[0044] 7a, a stopper layer 106 and a low piezoelectric layer 104 are formed on a substrate 105 by a method such as sputtering. In the first step, in order to make the low piezoelectric layer 104 have low piezoelectric properties, sputtering with a low power density may be used, the low piezoelectric layer 104 may be formed at a temperature lower than the temperature at which the main component of the low piezoelectric layer 104 crystallizes, or an additive that makes the low piezoelectric layer have low piezoelectric properties may be added.

[0045] When the main component material of the low-voltage piezoelectric layer 104 is, for example, KNN, the temperature of the support table on which the film formation target is placed is maintained at 25° C. or higher and 400° C. or lower, for example, 350° C. Then, sputtering is performed in an Ar atmosphere to form an amorphous KNN film.

[0046] In the second step shown in FIG. 7b, a lower electrode 103 is formed on the surface of the low-piezoelectric layer 104 by a method such as sputtering. Furthermore, a piezoelectric layer 102 is formed on the surface of the lower electrode 103 by sputtering or the like. The piezoelectric layer 102 is formed using a material that has the same main component as the low-piezoelectric layer 104, and is formed under conditions that result in a piezoelectric material. That is, the piezoelectric layer 102 may be formed using sputtering with a high power density, or may be formed at a temperature higher than the temperature at which the main component crystallizes. If the main component of the piezoelectric layer 102 is, for example, KNN, the piezoelectric layer 102 is formed at a temperature of, for example, 500°C or higher.

[0047] 7c, an electrode layer (not shown) is formed on the surface of the piezoelectric layer 102 by sputtering or the like, and the electrode layer is patterned by photolithography and etching to form an upper electrode 101 connecting the wiring 11 and the pad 12. Note that a resist may be patterned before the electrode layer is formed, and after the electrode layer is formed, a desired shape such as the upper electrode 101 may be patterned by lift-off. By forming the upper electrode 101, the laminated structure of the vibrating body 110 is obtained.

[0048] 8a, the piezoelectric layer 102 is etched to form a conductive hole 32 that reaches the lower electrode 103. The conductive hole 32 is formed in an area of ​​the surface of the piezoelectric layer 102 where the upper electrode 101 is not formed, for example, near the pad 12 of the upper electrode 101.

[0049] 8b, pads 31 are formed of a metal such as Au to be electrically connected to the lower electrodes 103. The formation of the pads 31 provides electrical connection with the lower electrodes 103, enabling connection between the vibrating body 110 and peripheral circuits.

[0050] In the sixth step shown in FIG. 8c, the substrate 105 is subjected to processing such as deep reactive ion etching (RIE) from the side opposite to the vibrating body 110 to form the cavity 51. Other dry etching may also be used as the processing. The processing to form the cavity 51 is stopped by the stopper layer 106, so that the vibrating body 110 is protected during the processing. The cavity 51 is formed to be larger than the upper electrode 101 when viewed from above.

[0051] Due to the formation of the cavity 51, the front and back sides of the center portion 112 of the vibrating body 110 are not supported. On the other hand, the edge portion 111 of the vibrating body 110 is supported by the substrate 105. For this reason, the center portion 112 bends around the area where the upper electrode 101 is formed, causing the vibrating body 110 to vibrate. The manufacturing method described above can easily obtain the structure of the pMUT 100 shown in Figures 1a and 1b. The manufacturing method can also be applied to the manufacturing of a modified pMUT 150 shown in Figures 2a and 2b. The manufacturing method can also be applied to the manufacturing of a modified pMUT 160 shown in Figure 3 by changing the order of film formation.

[0052] In the above description, a pMUT is shown as an application example of the piezoelectric element of the present invention, but the piezoelectric element of the present invention may also be applied to filter elements such as FBARs, resonators, duplexers, and the like. The piezoelectric element of the present invention may also be applied to actuators such as micropumps used in inkjet printing, RF-MEMS (Radio Frequency-Micro Electro Mechanical System) switches, optical mirrors, etc. Furthermore, the piezoelectric element of the present invention may also be applied to sensors such as acceleration sensors, gyro sensors, and energy harvesters. Furthermore, in the above explanation, an example in which the cavity 51 is formed in the substrate 105 has been shown, but the piezoelectric element of the present invention may also be one in which the cavity is formed between the substrate 105 and the vibrating body 110 . [Explanation of symbols]

[0053] 100, 150, 160 pMUT 101 Upper electrode 102 Piezoelectric layer 103 Lower electrode 104 Low voltage layer 105 PCB 51 Cavity 106 Stopper layer 110 Vibration body 111 Edge 112 Central

Claims

1. a structure in which a first electrode layer, a second electrode layer, a first layer located between the first electrode layer and the second electrode layer and having piezoelectricity, and a second layer provided between the first layer and the second electrode layer via the first electrode layer, having the same main component as the main component of the first layer and having lower piezoelectricity than the first layer, are laminated; a substrate supporting the edges of the structure; A piezoelectric element comprising:

2. The piezoelectric element according to claim 1 , wherein the second layer has almost no piezoelectricity.

3. The piezoelectric element according to claim 1 , wherein the second layer is a layer whose main component is amorphous.

4. The piezoelectric element according to claim 1 , wherein the second layer is a layer whose main component contains an additive.

5. The first layer and the second layer are made of AlN, PZT, KNN, or BiFeO ３ , BaTiO ３ , LiNbO ３ , LiTaO ３ 2. The piezoelectric element according to claim 1, which is made of a material containing one of ZnO and pVDF as a main component.

6. The first layer and the second layer are made of PZT, KNN, or BiFeO ３ , BaTiO ３ , LiNbO ３ and LiTaO ３ 2. The piezoelectric element according to claim 1, which is made of a material containing any one of the following as a main component.

7. The piezoelectric element according to claim 1 , further comprising a stopper layer on the substrate side of the structure, which stops the progress of a process that unsupports the portions of the structure other than the edge.

8. The piezoelectric element according to claim 1 , wherein a plurality of the structures are arranged in a direction in which the layers of the structures extend.

9. A method for manufacturing a piezoelectric element including a structure in which a second layer, a first electrode layer, a first layer, and a second electrode layer are stacked in this order, and a substrate that supports an edge of the structure, the method comprising: forming the first electrode layer; forming the second electrode layer; forming the first layer having piezoelectric properties; forming the second layer having the same main component as the first layer and lower piezoelectricity than the first layer; A method for manufacturing a piezoelectric element having the above structure.

10. The method for manufacturing a vibrator according to claim 9 , wherein the step of forming the second layer is performed at a temperature lower than a temperature at which a main component of the second layer crystallizes.

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