阅读说明：本技术 一种用于制作体声波器件的压电薄膜体及其制备方法 (Piezoelectric film body for manufacturing bulk acoustic wave device and preparation method thereof ) 是由 张秀全 王金翠 朱厚彬 李真宇 李洋洋 刘桂银 于 2020-04-27 设计创作，主要内容包括：本申请公开一种用于制作体声波器件的压电薄膜体及其制备方法,用于制作体声波器件的压电薄膜体包括依次叠加的薄膜体衬底、第一强化层、压电薄膜层和第二强化层；其中,所述第一强化层和所述第二强化层的杨氏模量大于所述压电薄膜层的杨氏模量。可以解决压电薄膜与金属电极直接接触以及在背面刻蚀过程中易过刻和在制备器件的过程中易碎裂等问题；同时制备方法,可以解决现有压电薄膜成膜方法容易产生晶格失配、热失配以及界面缺陷的问题。(The application discloses a piezoelectric film body for manufacturing a bulk acoustic wave device and a preparation method thereof, wherein the piezoelectric film body for manufacturing the bulk acoustic wave device comprises a film body substrate, a first strengthening layer, a piezoelectric film layer and a second strengthening layer which are sequentially superposed; wherein the Young's modulus of the first and second strengthening layers is greater than the Young's modulus of the piezoelectric thin film layer. The problems that the piezoelectric film is directly contacted with the metal electrode, easy to be etched in the back etching process, easy to be cracked in the device preparation process and the like can be solved; meanwhile, the preparation method can solve the problems that the existing piezoelectric film forming method is easy to generate lattice mismatch, thermal mismatch and interface defects.)

1. A piezoelectric film body for manufacturing a bulk acoustic wave device is characterized by comprising a film body substrate, a first strengthening layer, a piezoelectric film layer and a second strengthening layer which are sequentially stacked;

wherein the Young's modulus of the first and second strengthening layers is greater than the Young's modulus of the piezoelectric thin film layer.

2. The piezoelectric thin film body of claim 1, further comprising a spacer layer between the thin film body substrate and the first strengthening layer.

3. The piezoelectric thin film body of claim 2, wherein the first strengthening layer has a thickness in the range of 2nm to 100nm and the second strengthening layer has a thickness in the range of 2nm to 100 nm;

the thickness range of the piezoelectric film layer is 100nm-3000 nm.

4. The piezoelectric thin film body according to claim 2, wherein a material of the thin film body substrate is single crystal silicon or lithium niobate.

5. The piezoelectric thin film body according to claim 2, wherein a material of the first reinforcing layer and the second reinforcing layer is aluminum oxide or aluminum nitride;

the piezoelectric film layer is made of lithium niobate or lithium tantalate.

6. The piezoelectric film body according to claim 2, wherein the material of the isolation layer is silicon dioxide or silicon nitride.

7. A method for preparing a piezoelectric film body for manufacturing a bulk acoustic wave device, comprising:

manufacturing a first strengthening layer on the thin film substrate;

manufacturing a piezoelectric thin film layer on the first strengthening layer by an ion implantation bonding method;

and manufacturing a second strengthening layer on the piezoelectric thin film layer to obtain the piezoelectric thin film body for manufacturing the bulk acoustic wave device.

8. The method of claim 7, further comprising:

before the first strengthening layer is manufactured, an isolation layer is manufactured on the thin film bulk substrate.

9. The method of claim 7, wherein fabricating the first strengthening layer on the thin film bulk substrate comprises:

manufacturing a first strengthening layer on the film body substrate in a magnetron sputtering or atomic deposition mode;

and polishing the first strengthening layer to enable the thickness of the first strengthening layer to be in a range of 2nm-100 nm.

10. The method of claim 7, wherein fabricating a second stiffening layer on the piezoelectric thin film layer to obtain a piezoelectric thin film body for fabricating a bulk acoustic wave device comprises:

manufacturing a second strengthening layer on the piezoelectric thin film layer in a magnetron sputtering or atomic deposition mode;

and polishing the second strengthening layer to ensure that the thickness range of the second strengthening layer is 2nm-100nm, thereby obtaining the piezoelectric film body for manufacturing the bulk acoustic wave device.

Technical Field

The application relates to the technical field of piezoelectric films, in particular to a piezoelectric film body for manufacturing a bulk acoustic wave device and a preparation method thereof.

Background

With the development of piezoelectric film technology, piezoelectric films are increasingly applied to the manufacture of bulk acoustic wave devices. At present, the film structure of the piezoelectric film body is usually an oxide-piezoelectric film layer, and the film structure of the bulk acoustic wave device manufactured by adopting the piezoelectric film body is usually a metal-piezoelectric film body-metal.

However, in the manufactured bulk acoustic wave device, the piezoelectric thin film layer is in direct contact with metal, so that higher harmonics are easily generated, and the out-of-band suppression effect of the bulk acoustic wave device is poor. When the piezoelectric film body is used for manufacturing a bulk acoustic wave device, a substrate on the back side needs to be etched, and etching precision is difficult to control, so that over-etching is easy to occur; and because the stress intensity of the piezoelectric film layer is low, the piezoelectric film layer is easy to crack in the process of preparing the device, and the yield of the bulk acoustic wave device is greatly reduced. In addition, the existing film forming method of the piezoelectric film usually adopts pulse laser deposition, magnetron sputtering, atomic layer deposition, thermal evaporation and the like, and the problems of lattice mismatch, thermal mismatch, interface defects and the like are easily generated.

Disclosure of Invention

The application provides a piezoelectric film body for manufacturing a bulk acoustic wave device, which can solve the problems that a piezoelectric film is directly contacted with a metal electrode, and the piezoelectric film is easy to be etched in the back etching process and easy to be cracked in the device manufacturing process; meanwhile, the preparation method of the piezoelectric film body for manufacturing the bulk acoustic wave device is provided, and the problems that the existing piezoelectric film forming method is easy to generate lattice mismatch, thermal mismatch and interface defects can be solved.

On one hand, the piezoelectric film body for manufacturing the bulk acoustic wave device comprises a film body substrate, a first strengthening layer, a piezoelectric film layer and a second strengthening layer which are sequentially superposed;

wherein the Young's modulus of the first and second strengthening layers is greater than the Young's modulus of the piezoelectric thin film layer.

Optionally, the thin film bulk substrate further comprises a spacer layer, and the spacer layer is located between the thin film bulk substrate and the first strengthening layer.

Optionally, the thickness range of the first strengthening layer is 2nm to 100nm, and the thickness range of the second strengthening layer is 2nm to 100 nm;

the thickness range of the piezoelectric film layer is 100nm-3000 nm.

Optionally, the thin film bulk substrate is made of monocrystalline silicon or lithium niobate.

Optionally, the first strengthening layer and the second strengthening layer are made of aluminum oxide or aluminum nitride;

the piezoelectric film layer is made of lithium niobate or lithium tantalate.

Optionally, the isolation layer is made of silicon dioxide or silicon nitride.

In another aspect, a method for fabricating a piezoelectric thin film body for use in fabricating a bulk acoustic wave device includes:

manufacturing a first strengthening layer on the thin film substrate;

manufacturing a piezoelectric thin film layer on the first strengthening layer by an ion implantation bonding method;

and manufacturing a second strengthening layer on the piezoelectric thin film layer to obtain the piezoelectric thin film body for manufacturing the bulk acoustic wave device.

Optionally, a method for manufacturing a piezoelectric thin film body used for manufacturing a bulk acoustic wave device further includes:

before the first strengthening layer is manufactured, an isolation layer is manufactured on the thin film bulk substrate.

Optionally, the manufacturing of the first strengthening layer on the thin film bulk substrate includes:

manufacturing a first strengthening layer on the film body substrate in a magnetron sputtering or atomic deposition mode;

and polishing the first strengthening layer to enable the thickness of the first strengthening layer to be in a range of 2nm-100 nm.

Optionally, the manufacturing a second strengthening layer on the piezoelectric thin film layer to obtain a piezoelectric thin film body for manufacturing a bulk acoustic wave device includes:

manufacturing a second strengthening layer on the piezoelectric thin film layer in a magnetron sputtering or atomic deposition mode;

and polishing the second strengthening layer to ensure that the thickness range of the second strengthening layer is 2nm-100nm, thereby obtaining the piezoelectric film body for manufacturing the bulk acoustic wave device.

According to the technical scheme, the piezoelectric film body for manufacturing the bulk acoustic wave device comprises a film body substrate, a first strengthening layer, a piezoelectric film layer and a second strengthening layer which are sequentially stacked; wherein the Young's modulus of the first and second strengthening layers is greater than the Young's modulus of the piezoelectric thin film layer.

According to the piezoelectric film body for manufacturing the bulk acoustic wave device and the manufacturing method thereof, when the piezoelectric film body is used for manufacturing the bulk acoustic wave device, the metal electrode is manufactured on the piezoelectric film body, and the metal electrode is in direct contact with the second strengthening layer, so that the problem of generation of higher harmonics caused by direct contact of the piezoelectric film layer and the metal electrode can be solved; in the process of etching the back substrate, the first strengthening layer can effectively prevent over-etching. Because the thickness of the piezoelectric thin film layer is nanoscale, the strength is lower, the piezoelectric thin film layer is fragile and easy to crack in the process of preparing a device, the Young modulus of the first strengthening layer and the Young modulus of the second strengthening layer are larger than that of the piezoelectric thin film layer, the piezoelectric thin film layer is clamped between the first strengthening layer and the second strengthening layer, the piezoelectric thin film layer is supported, the strength of the piezoelectric thin film layer can be enhanced, and the piezoelectric thin film layer is prevented from being cracked. According to the preparation method of the piezoelectric film body, the piezoelectric film layer and the first strengthening layer are bonded together by adopting a bonding technology, the problems that lattice mismatch, thermal mismatch and interface defects are easily generated by the existing piezoelectric film forming method can be solved, and the piezoelectric film layer meeting the high film quality requirement is obtained.

Drawings

In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a structural diagram of a piezoelectric film bulk film layer for manufacturing a bulk acoustic wave device according to an embodiment of the present disclosure;

fig. 2 is a structural diagram of another piezoelectric film layer for manufacturing a bulk acoustic wave device according to an embodiment of the present disclosure;

FIG. 3 is a process flow diagram of a method for manufacturing a piezoelectric film body for use in fabricating a bulk acoustic wave device shown in FIG. 1;

fig. 4 is a process flow diagram of another method for manufacturing a piezoelectric film body for use in the bulk acoustic wave device shown in fig. 2.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

With the development of piezoelectric film technology, piezoelectric films are increasingly applied to the manufacture of bulk acoustic wave devices. At present, the film structure of the piezoelectric film body is usually an oxide-piezoelectric film layer, and the film structure of the bulk acoustic wave device manufactured by adopting the piezoelectric film body is usually a metal-piezoelectric film body-metal.

However, in the manufactured bulk acoustic wave device, the piezoelectric thin film layer is in direct contact with metal, so that higher harmonics are easily generated, and the out-of-band suppression effect of the bulk acoustic wave device is poor. When the piezoelectric film body is used for manufacturing a bulk acoustic wave device, a substrate on the back side needs to be etched, and etching precision is difficult to control, so that over-etching is easy to occur; and because the stress intensity of the piezoelectric film layer is low, the piezoelectric film layer is easy to crack in the process of preparing the device, and the yield of the bulk acoustic wave device is greatly reduced. In addition, the existing film forming method of the piezoelectric film usually adopts pulse laser deposition, magnetron sputtering, atomic layer deposition, thermal evaporation and the like, and the problems of lattice mismatch, thermal mismatch, interface defects and the like are easily generated.

In view of this, in one aspect, fig. 1 is a structural diagram of a piezoelectric film layer for fabricating a bulk acoustic wave device according to an embodiment of the present disclosure. As shown in fig. 1, a piezoelectric thin film body for manufacturing a bulk acoustic wave device includes a thin film body substrate 1, a first strengthening layer 2, a piezoelectric thin film layer 3, and a second strengthening layer 4, which are sequentially stacked; wherein, the Young's modulus of the first strengthening layer 2 and the second strengthening layer 4 is larger than that of the piezoelectric thin film layer 3.

The thickness H1 of the first strengthening layer 2 may be the same as or different from the thickness H3 of the second strengthening layer, and the thickness H1 of the first strengthening layer may range from 2nm to 100nm, and may be 10 nm. The thickness H2 of the piezoelectric thin film layer 3 is in the range of 100nm to 3000nm, and may be 400 nm. Because the electromechanical coupling coefficient of the film material can be influenced by the excessively thick film thickness, the electromechanical coupling coefficient of each film material of the piezoelectric film body can be ensured by controlling the thicknesses of the first strengthening layer 2, the piezoelectric film layer 3 and the second strengthening layer 4 at a nanometer level.

When the piezoelectric film body is used for manufacturing a bulk acoustic wave device, the metal electrode is manufactured on the piezoelectric film body, and the metal electrode is directly contacted with the second strengthening layer 4, so that the problem of generation of higher harmonics caused by direct contact of the piezoelectric film layer 3 and the metal electrode can be solved; the first strengthening layer 2 can effectively prevent over-etching during the process of etching the back substrate. Because, the thickness of piezoelectric thin film layer 3 is nanometer, and intensity is lower, is fragile, easy split in the in-process that is used for preparing the device, and the young modulus of first strengthening layer 2 and second strengthening layer 4 is greater than piezoelectric thin film layer 3, and first strengthening layer 2 and second strengthening layer 4 press from both sides piezoelectric thin film layer 3 in the middle, play the effect of support to piezoelectric thin film layer 3, can strengthen piezoelectric thin film layer 3's intensity, avoid piezoelectric thin film layer 3 to take place fragmentation.

The material of the film body substrate 1 can be monocrystalline silicon or lithium niobate, the monocrystalline silicon or lithium niobate can better prevent external impurity ions from entering the piezoelectric film body, and when the piezoelectric film body is used for preparing other devices, the film body substrate 1 needs to be removed, and the monocrystalline silicon or lithium niobate can be easily removed in an etching mode. The material of the first strengthening layer 2 and the second strengthening layer 4 can be aluminum oxide or aluminum nitride; the aluminum oxide film layer or the aluminum nitride film layer prepared by the magnetron sputtering or the deposition method has the characteristics of high acoustic velocity and high Young modulus, and can enhance the supporting effect of the first strengthening layer 2 and the second strengthening layer 4. In addition, when the thin film body substrate 1 is removed by etching, the aluminum oxide or aluminum nitride is not etched, so that the first strengthening layer made of aluminum oxide or aluminum nitride can prevent over-etching. Because the properties of lithium tantalate and lithium niobate are similar, the material of the piezoelectric thin film layer 3 can be single crystal lithium niobate or single crystal lithium tantalate, and the piezoelectric thin film layer 3 is a single crystal thin film layer, so that the physical properties of the material, such as electromechanical coupling coefficient, sound velocity and the like, can be completely reserved. When the piezoelectric film body is used for preparing a bulk acoustic wave device, the sound velocity of the first strengthening layer 2 and the second strengthening layer 4 is lower than that of the piezoelectric film layer 3 and higher than that of an air medium, most of sound waves are reflected when being transmitted to the interface between the piezoelectric film layer 3 and the first strengthening layer 2 or the second strengthening layer 4, and meanwhile, reflection is also generated on the interface between the first strengthening layer 2 or the second strengthening layer 4 and air, so that the sound waves can be completely reserved in the piezoelectric film body and are not leaked to the outside, the performance failure of the acoustic wave device can be avoided, the generation of higher harmonics can be further inhibited, and the out-of-band inhibition effect of the device is improved.

Fig. 2 is a structural diagram of another piezoelectric film layer for manufacturing a bulk acoustic wave device according to an embodiment of the present disclosure. As shown in fig. 2, the piezoelectric thin film body further comprises an isolation layer 5, and the isolation layer 5 is located between the thin film body substrate 1 and the first strengthening layer 2. The material of the isolation layer 5 may be silicon dioxide or silicon nitride. Because, when the piezoelectric film body is used for preparing a bulk acoustic wave device, the film body substrate 1 needs to be removed, and after the film body substrate 1 is removed, the silicon dioxide or silicon nitride as the isolation layer 5 can play a role in protecting the first strengthening layer for isolating external impurity ions.

On the other hand, fig. 3 is a process flow chart of a method for manufacturing a piezoelectric thin film body for manufacturing a bulk acoustic wave device shown in fig. 1. As shown in fig. 3, a method for manufacturing a piezoelectric thin film body for use in fabricating a bulk acoustic wave device includes:

s1: a first strengthening layer 2 is fabricated on a thin film bulk substrate 1.

S1, fabricating the first strengthening layer 2 on the thin film bulk substrate 1, may include:

s11: and manufacturing a first strengthening layer 2 on the thin film bulk substrate 1 by means of magnetron sputtering or atomic deposition.

S12: the first strengthening layer 2 is polished so that the thickness of the first strengthening layer 2 is in the range of 2nm to 100 nm.

The film body substrate 1 can be a monocrystalline silicon wafer or a monocrystalline lithium niobate wafer with the diameter of 3 inches and the thickness of 0.4mm, and the roughness of the surface of the wafer can be less than 0.5 nm; the first strengthening layer 2 can be formed on the smoother side of the thin film bulk substrate 1. The first strengthening layer 2 can be alumina or aluminum nitride, and the film quality is uniform, wherein the alumina or aluminum nitride is formed by magnetron sputtering or atomic deposition. The polishing process can enable the surface of the first strengthening layer 2 to be smoother and the film thickness to be more uniform, and further, other film layers can be favorably adhered to the first strengthening layer 2.

S2: and manufacturing the piezoelectric film layer on the first strengthening layer by an ion implantation bonding method.

S2, fabricating the piezoelectric thin film layer on the first strengthening layer by ion implantation and bonding method, which includes the following steps:

s21: helium ions are implanted into the surface of the piezoelectric thin film body material, and the piezoelectric thin film layer 3, the separation layer and the excess material layer are formed in this order on the ion implantation side of the piezoelectric thin film body material.

The helium ions are injected to enable the piezoelectric film body material to be layered, the piezoelectric film layer 3 is located on the surface of the piezoelectric film body material, the separation layer is located between the piezoelectric film layer 3 and the residual material layer, the injected helium ions are distributed in the separation layer, and the piezoelectric film bodyThe material can be lithium niobate wafer or lithium tantalate wafer with the diameter of 3 inches and the thickness of 0.4 mm. The energy range of the helium ion implantation is 50-1000KeV, which may be 200KeV, and the dose range is 1E16-1E17ions/cm²And may be 4E16ions/cm²The present application is not particularly limited.

S22: the piezoelectric thin-film layer 3 and the first reinforcing layer 2 are bonded together.

Step S22 uses a bonding technique, which may be any one of a direct bonding method, an anodic bonding method, a low temperature bonding method, a vacuum bonding method, a plasma enhanced bonding method, and a bonding method, to bond the piezoelectric thin film layer 3 and the first reinforcing layer 2 together, so as to obtain a bonded body. The problems of lattice mismatch, thermal mismatch and interface defects easily generated by the conventional piezoelectric film forming method can be solved, and the piezoelectric film layer 3 meeting the requirement of high film quality can be obtained.

S23: and (3) separating the residual material layer from the piezoelectric film layer 3 by adopting a thermal stripping process.

After the piezoelectric thin film layer 3 and the first strengthening layer 2 are bonded together, the bonding body is placed into heating equipment, heat preservation is carried out at the temperature of 100-600 ℃, the temperature can be 400 ℃, the heat preservation environment is one of a vacuum environment, a nitrogen environment or an inert gas environment, the heat preservation time range is 1 minute-48 hours, 3 hours or 4 hours, and the piezoelectric thin film layer 3 is separated from the residual material layer at the separation layer until the piezoelectric thin film layer 3 is kept on the bonding body.

S3: and manufacturing a second strengthening layer on the piezoelectric thin film layer 3 to obtain the piezoelectric thin film body for manufacturing the bulk acoustic wave device.

S3, fabricating a second strengthening layer on the piezoelectric thin film layer 3 to obtain a piezoelectric thin film body for fabricating a bulk acoustic wave device, the method may include the following steps:

s31: and manufacturing a second strengthening layer 4 on the piezoelectric thin film layer 3 in a magnetron sputtering or atomic deposition mode.

S32: and polishing the second strengthening layer 4 to ensure that the thickness range of the second strengthening layer 4 is 2nm-100nm, thereby obtaining the piezoelectric film body for manufacturing the bulk acoustic wave device.

The second reinforcing layer 4 may be formed in the same manner as the first reinforcing layer 2 or in a different manner, and the present application is not particularly limited. The thickness of the second reinforcing layer 4 may be the same as or different from the thickness of the first reinforcing layer 2, and the present application is not particularly limited.

Fig. 4 is a process flow diagram of another method for manufacturing a piezoelectric film body for use in the bulk acoustic wave device shown in fig. 2. As shown in fig. 4, another method for manufacturing a piezoelectric thin film body for manufacturing a bulk acoustic wave device according to this embodiment includes the following steps:

s0: an isolation layer 5 is fabricated on the thin film bulk substrate 1.

The isolation layer 5 may be silicon dioxide or silicon nitride, and may be formed by plasma chemical vapor deposition, which is not particularly limited in this application. The film body substrate 1 can be a monocrystalline silicon wafer or a monocrystalline lithium niobate wafer with the diameter of 3 inches and the thickness of 0.4mm, and the roughness of the surface of the wafer can be less than 0.5 nm; the isolation layer 5 may be formed on the smoother surface of the thin film bulk substrate 1. The isolation layer 5 can be polished after forming a film, and after polishing, the isolation layer 5 can be better adhered to other film layers.

S1: the first strengthening layer 2 is made on the isolation layer 5.

The first strengthening layer 2 can be alumina or aluminum nitride, and the film quality is uniform, wherein the alumina or aluminum nitride is formed by magnetron sputtering or atomic deposition. Polishing treatment can be carried out after the first strengthening layer 2 is formed into a film, the polishing can enable the surface of the first strengthening layer 2 to be more smooth and the film thickness to be more uniform, and then, the adhesion of other films on the first strengthening layer 2 is facilitated.

S2: the piezoelectric thin film layer 3 is formed on the first reinforcing layer 2 by an ion implantation bonding method.

The piezoelectric film body material is layered by performing ion implantation on the piezoelectric film body material, and is divided into a residual material layer, a separation layer and a piezoelectric film layer 3, wherein the piezoelectric film layer 3 is positioned on the surface of the piezoelectric film body material, and the separation layer is positioned between the residual material layer and the piezoelectric film layer 3. The bonding method can be any one of a direct bonding method, an anodic bonding method, a low-temperature bonding method, a vacuum bonding method, a plasma strengthening bonding method and a bonding method, the first strengthening layer and the piezoelectric thin film layer 3 can be bonded together through the bonding method, the problems that the existing film forming method of the piezoelectric thin film layer is easy to generate lattice mismatch, thermal mismatch and interface defects can be solved, and the piezoelectric thin film layer 3 meeting the high film quality requirement is obtained.

S3: and manufacturing a second strengthening layer 4 on the piezoelectric thin film layer 3 to obtain the piezoelectric thin film body for manufacturing the bulk acoustic wave device.

When the piezoelectric film body for manufacturing the bulk acoustic wave device is used for manufacturing the bulk acoustic wave device, the metal electrode is manufactured on the piezoelectric film body, and the metal electrode is directly contacted with the second strengthening layer, so that the problem of generation of higher harmonics caused by direct contact of the piezoelectric film layer and the metal electrode can be solved; in the process of etching the back substrate, the first strengthening layer can effectively prevent over-etching. Because, the thickness of piezoelectric thin film layer is nanometer, and intensity is lower, is fragile, easy split in the in-process that is used for preparing the device, and the young modulus of first strengthening layer and second strengthening layer is greater than piezoelectric thin film layer's young modulus, and piezoelectric thin film layer is pressed from both sides in the middle to first strengthening layer and second strengthening layer, plays the effect of support to piezoelectric thin film layer, can strengthen piezoelectric thin film layer's intensity to protect piezoelectric thin film layer to avoid taking place cracked. According to the preparation method of the piezoelectric film body, the piezoelectric film layer and the first strengthening layer are bonded together by adopting a bonding technology, the problems that lattice mismatch, thermal mismatch and interface defects are easily generated by the existing piezoelectric film forming method can be solved, and the piezoelectric film layer meeting the high film quality requirement is obtained. The first strengthening layer and the second strengthening layer are prepared on two sides of the piezoelectric thin film layer, the piezoelectric thin film layer is clamped between the first strengthening layer and the second strengthening layer, the piezoelectric thin film layer is supported, the strength of the piezoelectric thin film layer can be enhanced, and the piezoelectric thin film layer is prevented from being cracked.

The same and similar parts in the various embodiments in this specification may be referred to each other. In particular, for the embodiments, since they are substantially similar to the method embodiments, the description is simple, and the relevant points can be referred to the description in the method embodiments.