Acoustic wave resonator structure, acoustic wave device and preparation method thereof

Abstract

The present invention provides an acoustic wave resonator structure, an acoustic wave device and a preparation method thereof. By arranging a polarization zone in which each parameter in a piezoelectric constant matrix is ​​the inverse of a corresponding parameter in the piezoelectric constant matrix of the piezoelectric crystal in a piezoelectric crystal directly below an air gap region, the excitation of high-order transverse stray modes can be effectively reduced or even eliminated, intra-band fluctuations can be effectively reduced, insertion loss and clutter interference in a passband can be reduced, and a flat passband response can be achieved. The scheme is simple, there is no need to deform the interdigital electrodes, the preparation process is simple, the success rate is high, and the yield rate is high.

Description

Technical Field

[0001] The invention belongs to the field of microelectronic technology and relates to an acoustic wave resonator structure, an acoustic wave device and a preparation method thereof. Background Art

[0002] In response to the development needs of miniaturization and low cost of RF mobile terminals, acoustic wave devices have shown significant advantages due to their small size, simple manufacturing process and high performance. However, there are still problems to be solved in acoustic wave devices, such as the excitation of stray acoustic wave modes. For example, when the target mode is excited, unnecessary multi-order transverse stray modes will be generated between the resonant frequency and anti-resonant frequency of the target mode. Therefore, there will be multiple stray resonance peaks distributed in the device response, and corresponding ripples will appear in the passband of the filter device, resulting in increased insertion loss and poor passband edge steepness, which will seriously affect the accuracy and stability of signal reception and transmission.

[0003] The prior art proposes a scheme for deforming the patterned electrode design, such as changing the trace electrode to adjust the lateral resonance cavity length of each fork finger to eliminate high-order stray resonance peaks, but this method will also deteriorate the resonance performance of the target mode, leading to problems such as a decrease in the device quality factor; another example is adjusting the duty cycle or mass loading of different areas of the fork finger electrode to adjust the velocity profile curve to suppress high-order stray modes, but this method will increase the accuracy requirements of the electrode line width, increase the process difficulty and processing cost.

[0004] Therefore, it is necessary to provide an acoustic wave resonator structure, an acoustic wave device and a method for preparing the same. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an acoustic wave resonator structure, an acoustic wave device and a method for preparing the same, so as to solve the problem of lateral stray modes appearing in the response of acoustic wave devices in the prior art.

[0006] To achieve the above objectives and other related objectives, the present invention provides an acoustic wave resonator structure, the acoustic wave resonator structure comprising:

[0007] a supporting substrate;

[0008] a piezoelectric layer, the piezoelectric layer being located on the upper surface of the supporting substrate;

[0009] A patterned electrode, the patterned electrode is located on the upper surface of the piezoelectric layer, wherein the patterned electrode includes a central interdigital region and reflective grating regions located on both sides of the central interdigital region in the direction of acoustic wave propagation, and the central interdigital region includes a first bus bar region, a first air gap region, an aperture region, a second air gap region, and a second bus bar region in the aperture direction;

[0010] A polarization zone, wherein the polarization zone is formed by polarizing a local area of ​​the piezoelectric layer, wherein each parameter in the piezoelectric constant matrix of the polarization zone is the inverse of the corresponding parameter in the piezoelectric constant matrix of the unpolarized area of ​​the piezoelectric layer, wherein the polarization zone includes a first polarization zone in the piezoelectric layer corresponding to the first air gap zone and a second polarization zone in the piezoelectric layer corresponding to the second air gap zone, and the first polarization zone and the second polarization zone are symmetrically distributed.

[0011] Optionally, a piezoelectric single crystal substrate is provided to replace the stacked support substrate and the piezoelectric layer, and the piezoelectric single crystal substrate and the piezoelectric layer are made of the same material.

[0012] Optionally, the shape of the polarization zone includes one or a combination of a triangle, a rectangle, a trapezoid, a pentagon, a hexagon, a circle or an ellipse.

[0013] Optionally, the distribution of the polarization zones in the direction of sound wave propagation includes continuous distribution or spaced distribution.

[0014] Optionally, λ is defined as the wavelength of the target sound wave, that is, the period of the interdigitated electrodes. When the thickness of the piezoelectric layer is h, the thickness of the polarization zone is 0.05λ-h; when the thickness of the piezoelectric single crystal substrate is T, the thickness of the polarization zone is 0.05λ-T.

[0015] Optionally, a boundary of the polarization zone contacts an end of the aperture zone.

[0016] Optionally, the piezoelectric layer corresponding to the first bus bar area and / or the second bus bar area also includes the polarization area; the polarization area corresponding to the first bus bar area and the polarization area corresponding to the second bus bar area are symmetrically or asymmetrically distributed.

[0017] Optionally, it further includes a first additional finger located in the first air gap region and a second additional finger located in the second air gap region, wherein the first additional finger is electrically connected to the first bus bar, and the second additional finger is electrically connected to the second bus bar.

[0018] The present invention also provides an acoustic wave device, which includes any of the acoustic wave resonator structures; the acoustic wave device includes at least one of a filter, a duplexer and a multiplexer.

[0019] The present invention also provides a method for preparing any of the acoustic wave resonator structures, comprising the following steps:

[0020] Polarizing a part of the piezoelectric layer or the piezoelectric single crystal substrate to form the polarization region, and leaving an alignment mark;

[0021] Based on the alignment mark, forming the patterned electrode on the piezoelectric layer;

[0022] The preparation method of the polarization zone includes local bonding, local ion implantation, physical vapor deposition, chemical vapor deposition, magnetron sputtering or Czochralski crystal growth.

[0023] As described above, the acoustic wave resonator structure, acoustic wave device and preparation method thereof of the present invention can effectively reduce or even eliminate the excitation of high-order transverse stray modes, effectively reduce intra-band fluctuations, reduce insertion loss and clutter interference in the passband, and achieve a flat passband response by setting a polarization zone in which each parameter in the piezoelectric constant matrix is ​​the inverse of the corresponding parameter in the piezoelectric constant matrix of the piezoelectric crystal in the piezoelectric crystal corresponding to the air gap zone. The scheme is simple, there is no need to deform the interdigital electrodes, the preparation process is simple, the success rate is high, and the yield rate is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a schematic cross-sectional view of an acoustic wave resonator structure based on a piezoelectric single crystal substrate in the present invention.

[0025] Figure 2 Shown is a schematic diagram of a top view of the interdigitated electrodes of the acoustic wave resonator structure proposed by the present invention.

[0026] Figure 3 It shows a schematic diagram comparing the crystal coordinate systems of the piezoelectric crystal before and after polarization in the acoustic wave resonator structure based on the piezoelectric single crystal substrate in the present invention.

[0027] Figure 4 Shown is a comparison diagram of simulated admittance curves of excited horizontal shear waves in the structures of Comparative Example 1, Example 1 and Example 2 of the present invention.

[0028] Figure 5 It is a schematic diagram showing the comparison of the crystal coordinate system of the piezoelectric crystal before and after polarization in the acoustic wave resonator structure based on a heterogeneous substrate in the present invention.

[0029] Figure 6 Shown are schematic top-view structures of interdigital electrodes of a conventional acoustic wave resonator and the acoustic wave resonator proposed by the present invention.

[0030] Figure 7 Shown is a comparison diagram of simulated admittance curves of excited horizontal shear waves in the structures of Comparative Example 2, Example 3 and Example 4 of the present invention.

[0031] Figure 8 It shows a schematic diagram comparing the crystal coordinate systems of the piezoelectric crystals before and after polarization in the structures of Comparative Example 3 and Example 5 of the present invention.

[0032] Fig. 9Shown is a schematic diagram of the distribution of polarization regions in the acoustic wave resonator structure proposed by the present invention.

[0033] Fig.10 FIG. 4 is a schematic diagram showing the distribution of patterned electrodes in the acoustic wave resonator structure proposed by the present invention.

[0034] Description of Reference Numerals

[0035] 100 Support substrate

[0036] 200 Piezoelectric layer

[0037] 110 Piezoelectric single crystal substrate

[0038] 300 Patterned Electrode

[0039] 401 First Polarization Zone

[0040] 402 Second Polarization Zone

[0041] 501 First Supplementary Index

[0042] 502 Second additional index DETAILED DESCRIPTION

[0043] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0044] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0045] For ease of description, spatial relational terms such as “under”, “below”, “below”, “below”, “over”, etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other orientations of the device in use or operation in addition to the orientation depicted in the drawings, and may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, so that the first and second features may not be in direct contact. In addition, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or one or more intervening layers may also be present.

[0046] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0047] like Figure 5 , Figure 6 and Fig.10 The present application provides an acoustic wave resonator structure, which includes: a supporting substrate 100, a piezoelectric layer 200, a patterned electrode 300 and a polarization region, wherein the piezoelectric layer 200 is located on the upper surface of the supporting substrate 100; the patterned electrode 300 is located on the upper surface of the piezoelectric layer 200, and the patterned electrode 300 includes a central interdigital region and reflective grating regions (not shown) located on both sides of the central interdigital region in the direction of acoustic wave propagation (defined as a first direction), and the central interdigital region includes a first bus bar region, a first air gap region, and a second air gap region in the aperture direction (defined as a second direction). zone, an aperture zone, a second air gap zone and a second bus bar zone, the first bus bar and the second bus bar are electrically connected to the electrical signal and the ground signal, respectively; each parameter in the piezoelectric constant matrix of the polarization zone is the inverse of the corresponding parameter in the piezoelectric constant matrix of the piezoelectric layer 200, wherein the polarization zone includes a first polarization zone 401 in the piezoelectric layer 200 corresponding to the first air gap zone and a second polarization zone 402 in the piezoelectric layer 200 corresponding to the second air gap zone, and the first polarization zone 401 and the second polarization zone 402 are symmetrically distributed.

[0048] Among them, Figure 5 The polarization zone located in the piezoelectric layer 200 is formed by rotating 180° counterclockwise with the first direction as the axis of the X direction in the figure based on the tangent direction of the piezoelectric layer 200. Since each parameter in the piezoelectric constant matrix of the polarization zone located in the piezoelectric layer 200 is the inverse of the corresponding parameter in the piezoelectric constant matrix of the piezoelectric layer 200, the excitation of the spurious mode can be weakened and eliminated, the loss of the transmission signal is reduced, and the excitation of the target sound wave is not affected, so as to achieve a flat passband response.

[0049] like Figure 1 to Figure 3 The present application also provides an acoustic wave resonator structure, which includes: a piezoelectric single crystal substrate 110, a patterned electrode 300 and a polarization region. In this structure, the piezoelectric single crystal substrate 110 can be regarded as a substitute for the stacked supporting substrate 100 and the piezoelectric layer 200, and the material of the piezoelectric single crystal substrate 110 can be consistent with that of the piezoelectric layer 200.

[0050] As an example, the shape of the polarization region may include one or a combination of a triangle, a rectangle, a trapezoid, a pentagon, a hexagon, a circle or an ellipse.

[0051] Specifically, Fig. 9 Several polarization zones with different morphologies are illustrated, but the shapes of the polarization zones are not limited thereto and can be set according to specific needs.

[0052] As an example, the distribution of the polarization regions in the direction of propagation of the acoustic wave may include continuous distribution or spaced distribution.

[0053] As an example, the piezoelectric layer 200 corresponding to the first bus bar area and / or the second bus bar area may also include the polarization area; wherein the polarization area corresponding to the first bus bar area and the polarization area corresponding to the second bus bar area may be distributed symmetrically or asymmetrically.

[0054] Specifically, the distribution of the polarization zone in the piezoelectric layer 200 in the first direction may be discontinuous or continuous. In the second direction, the polarization zone must be located directly below the air gap zone, or located directly below the air gap zone and the bus bar zone, and the distribution of the polarization zone located directly below the air gap zone is symmetrical, but the polarization zone located directly below the bus bar zone may be asynchronous or have different morphologies, that is, the first bus bar zone may be correspondingly provided with the polarization zone, and the second bus bar zone may not be provided with the polarization zone, or the polarization zone corresponding to the first bus bar zone and the polarization zone corresponding to the second bus bar zone may have different morphologies, and of course, the polarization zone corresponding to the first bus bar zone and the polarization zone corresponding to the second bus bar zone may also be symmetrically provided.

[0055] As an example, it is preferred that the boundary of the polarization zone contacts the end of the aperture zone, that is, it is preferred that the polarization zone occupies the entire corresponding air gap zone in the second direction to improve the effect.

[0056] As an example, define λ as the wavelength of the target sound wave, that is, the period of the interdigitated electrodes. When the thickness of the piezoelectric layer 200 is h, the thickness of the polarization zone is 0.05λ-h; when the thickness of the piezoelectric single crystal substrate 110 is T, the thickness of the polarization zone is 0.05λ-T.

[0057] Specifically, in the thickness direction (defined as the third direction), the polarization zone may be located in the surface layer of the piezoelectric layer 200, or the polarization zone may be located in the inner layer of the piezoelectric layer 200, and when a heterogeneous substrate of a supporting substrate 100 + a piezoelectric layer 200 is used, if the thickness of the piezoelectric layer 200 is h, then in the third direction, the thickness of the polarization zone is 0.05λ-h, and when the piezoelectric single crystal substrate 110 is used, when the thickness of the piezoelectric single crystal substrate 110 is T, the thickness of the polarization zone is 0.05λ-T, wherein λ is the wavelength of the target sound wave, which is equal to the period of the interdigitated electrode.

[0058] As an example, Fig. 9 (h)~ Fig. 9 (k) further comprising a first additional finger 501 located in the first air gap region and a second additional finger 502 located in the second air gap region, wherein the first additional finger 501 is electrically connected to the first bus bar, and the second additional finger 502 is electrically connected to the second bus bar. The polarization region may or may not exist in the piezoelectric layer directly below the first additional finger 501 and the second additional finger 502, and the specific configuration may be as required.

[0059] The present application also provides an acoustic wave device, which includes any of the above-mentioned acoustic wave resonator structures, wherein the acoustic wave device may include at least one of a filter, a duplexer and a multiplexer, and the specific type is not limited here.

[0060] The present application also provides a method for preparing an acoustic wave resonator structure, comprising the following steps:

[0061] Providing the supporting substrate 100;

[0062] forming the piezoelectric layer 200 on the surface of the supporting substrate 100;

[0063] Polarizing a local area of ​​the piezoelectric layer 200 to form the polarization area, and leaving an alignment mark;

[0064] The patterned electrode is disposed based on the alignment mark.

[0065] The stacked structure of the support substrate 100 and the piezoelectric layer 200 may also be replaced by the piezoelectric single crystal substrate 110 having the same material as that of the piezoelectric layer 200 .

[0066] The method for forming the piezoelectric layer 200 on the surface of the supporting substrate 100 includes but is not limited to: ion implanting a piezoelectric single crystal and then bonding and peeling it with the supporting substrate 100 to transfer the piezoelectric layer 200 to the upper surface of the supporting substrate 100; or bonding the piezoelectric single crystal to the supporting substrate 100 and then grinding and polishing it to a target thickness; or forming the piezoelectric layer 200 on the surface of the supporting substrate 100 by physical vapor deposition, chemical vapor deposition, magnetron sputtering, Czochralski crystal growth, etc., and the specific preparation method is not overly limited.

[0067] The preparation method of the polarization zone can be to open a window locally in the target area and then perform local bonding, or to achieve regulation of material properties through local ion implantation, etc.; it can also be deposited by physical vapor deposition, chemical vapor deposition, magnetron sputtering or Czochralski crystal growth, etc. The specific preparation method is not overly limited.

[0068] The acoustic wave resonator structure in the present application is further introduced below in combination with comparative examples and specific examples.

[0069] Comparative Example 1: Figure 1 The lithium tantalate (LiTaO 3 ) A cross-sectional view of the acoustic wave resonator structure with a piezoelectric single crystal as the piezoelectric single crystal substrate and metal Al as the patterned electrode, which excites the horizontal shear wave SH-SAW mode. The top view is shown in Figure 2 (a).

[0070] Example 1 and Example 2: LiTaO 3 The piezoelectric single crystal is used as the piezoelectric single crystal substrate, and the metal Al is used as the patterned electrode to excite the horizontal shear wave SH-SAW mode, and the piezoelectric layer includes a piezoelectric polarization area located directly below the entire air gap area. The cross-sectional schematic diagram of the resonator structure is the same as that of Comparative Example 1, as shown in FIG. Figure 1 As shown, the top view is Figure 2 (b).

[0071] In the structures shown in Comparative Example 1, Example 1 and Example 2, LiTaO 3 The substrate is a single crystal substrate with a thickness of 500 μm, the patterned Al electrode has a thickness of 80 nm, the interdigital period is 1.2 μm, and the duty cycle is 0.5. In Example 1, the thickness of the polarization region in the third direction is 90 nm, and in Example 2, the thickness of the polarization region in the third direction is 360 nm.

[0072] LiTaO was cut by rotating YX 42° 3 The piezoelectric substrate, the Euler angle is set to (0, 48, 0), and the crystal coordinate system of the unpolarized region is as follows Figure 3(a), its elastic constant, piezoelectric constant and relative dielectric constant matrices are shown in equations (1), (3) and (5), respectively.

[0073] Spin-cut LiTaO in polarization region 3 The Euler angles of the piezoelectric crystal are set to (0, 228, 0), and the crystal coordinate system of the polarization region is as follows: Figure 3 (b), its elastic constant, piezoelectric constant and relative dielectric constant matrices are shown in equations (2), (4) and (6).

[0074]

[0075] By comparing the three types of matrices separately, it can be found that the parameters of the elastic constant and relative dielectric constant matrices remain unchanged before and after polarization, and each parameter of the crystal piezoelectric constant matrix after polarization is the inverse of the corresponding parameter of the crystal piezoelectric constant matrix before polarization.

[0076] Based on the structures shown in Comparative Example 1, Example 1 and Example 2, the simulated admittance curves of the acoustic wave resonator are as follows: Figure 4 As shown. In the case of comparative example 1, the spurious mode excitation in the passband is more significant, which will cause large in-band fluctuations, increase insertion loss, and seriously interfere with signal transmission. For example 1, when the polarization thickness is 90nm, significant suppression of the lateral stray mode can be achieved; and for example 2, when the polarization thickness reaches 360nm, the lateral stray mode is completely suppressed and eliminated, showing effective lateral stray mode suppression, so that the corresponding acoustic wave device can obtain a flat passband response and effectively reduce in-band jitter and loss. The admittance ratios of the target modes under the three structures are 81.4dB, 82.6dB and 81.8dB, respectively, indicating that the excitation of the target mode is not affected, and the electromechanical coupling coefficients are 8.82%, 8.36% and 8.20%, respectively, which are not significantly reduced. Therefore, corresponding to the above analysis, the resonator structure proposed in this application is not affected by the excitation of the target mode, and can effectively suppress the excitation of the lateral stray mode.

[0077] Comparative Example 2: Using silicon carbide (SiC) as the supporting substrate, rotating YX 42° to cut LiTaO 3 The piezoelectric single crystal film is used as the piezoelectric layer, and the metal Al is used as the patterned electrode to excite the horizontal shear wave SH-SAW mode. The structural diagram of the resonator is shown in Figure 5 As shown in (a), at this time, LiTaO 3 There is no polarization region in the piezoelectric single crystal film. The crystal coordinate system is marked on Figure 5 (a) on the left.

[0078] Example 3 and Example 4: SiC as the supporting substrate, LiTaO 3The piezoelectric single crystal film is used as the piezoelectric layer, and the metal Al is used as the patterned electrode to excite the horizontal shear wave SH-SAW mode. The piezoelectric layer includes a polarization region located directly below the air gap region. The structural diagram of the resonator is shown in Figure 5 As shown in (b), LiTaO 3 There are polarization regions in piezoelectric single crystal films. The crystal coordinate system of the polarization regions is marked on Figure 5 On the left side of (b), the crystal coordinate system of other regions is the same as Figure 5 (a).

[0079] In the structures shown in Comparative Example 2, Example 3 and Example 4, LiTaO 3 The thickness of the piezoelectric single crystal film is 360nm, the thickness of the Al electrode is 80nm, the interdigital period is 1.2μm, and the duty cycle is 0.5. Figure 6 (b), in Example 3, the polarization region is the entire air gap region, the entire interdigital period in the first direction, and Figure 6 As shown in (c), in Example 4, the polarization region is a local air gap region, which is only the middle half of the interdigital period in the first direction, wherein the thickness of the polarization region in the third direction is 360nm.

[0080] Based on the structures shown in Comparative Example 2, Example 3 and Example 4, the simulated admittance and conductance curves of the acoustic wave resonator are as follows: Figure 7 As shown. In the case of comparative example 2, the spurious mode excitation in the passband is very significant, which will cause large in-band fluctuations, increase insertion loss, and seriously interfere with the signal transmission by clutter. For example 4, when the polarization thickness is 360nm and the polarization zone is half a finger period in the first direction, most of the transverse spurious modes can be suppressed or weakened. For example 3, when the polarization thickness is 360nm and the polarization zone is the entire finger period in the first direction, the transverse spurious mode is further suppressed, and the acoustic wave device can obtain a relatively flat passband response and effectively reduce the in-band jitter and loss.

[0081] Comparative Example 3 and Example 5: Here is another example of tangential piezoelectric crystal polarization, which shows that the polarization zone is obtained based on how the original crystal is rotated.

[0082] Lithium niobate LiNbO with X tangent 3 The piezoelectric single crystal is used as the piezoelectric single crystal substrate, and metal Al is used as the patterned electrode to excite the horizontal shear wave SH-SAW mode. The situations with and without the polarization zone are respectively used as comparative example 3 and example 5. Figure 8 A schematic diagram showing the comparison of the crystal coordinate system before and after polarization of the piezoelectric crystal in the acoustic wave resonator structure.

[0083] Fig. 9The morphology of the polarization zones in some acoustic wave resonator structures proposed in this application is also shown, but the morphology and distribution of the polarization zones are not limited to this.

[0084] In summary, the acoustic wave resonator structure, acoustic wave device and preparation method of the present invention can effectively reduce or even eliminate the excitation of high-order transverse stray modes, effectively reduce intra-band fluctuations, reduce insertion loss and clutter interference in the passband, and achieve a flat passband response by setting a polarization zone in which each parameter in the piezoelectric constant matrix is ​​the inverse of the corresponding parameter in the piezoelectric constant matrix of the piezoelectric crystal in the piezoelectric crystal corresponding to the air gap zone. The scheme is simple, there is no need to deform the interdigital electrodes, the preparation process is simple, the success rate is high, and the yield rate is high.

[0085] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An acoustic wave resonator structure, characterized in that: The acoustic wave resonator structure comprises: a supporting substrate; a piezoelectric layer, the piezoelectric layer being located on the upper surface of the supporting substrate; A patterned electrode, the patterned electrode is located on the upper surface of the piezoelectric layer, wherein the patterned electrode includes a central interdigital region and reflective grating regions located on both sides of the central interdigital region in the direction of acoustic wave propagation, and the central interdigital region includes a first bus bar region, a first air gap region, an aperture region, a second air gap region, and a second bus bar region in the aperture direction; A polarization zone, wherein the polarization zone is formed by polarizing a local area of ​​the piezoelectric layer, wherein each parameter in the piezoelectric constant matrix of the polarization zone is the inverse of the corresponding parameter in the piezoelectric constant matrix of the unpolarized area of ​​the piezoelectric layer, wherein the polarization zone includes a first polarization zone in the piezoelectric layer corresponding to the first air gap zone and a second polarization zone in the piezoelectric layer corresponding to the second air gap zone, and the first polarization zone and the second polarization zone are symmetrically distributed.

2. The acoustic wave resonator structure according to claim 1, characterized in that: A piezoelectric single crystal substrate is provided to replace the stacked support substrate and the piezoelectric layer, and the piezoelectric single crystal substrate and the piezoelectric layer are made of the same material.

3. The acoustic wave resonator structure according to claim 1 or 2, characterized in that: The shape of the polarization region includes one or a combination of triangle, rectangle, trapezoid, pentagon, hexagon, circle or ellipse.

4. The acoustic wave resonator structure according to claim 1 or 2, characterized in that: The distribution of the polarization regions in the direction of sound wave propagation includes continuous distribution or spaced distribution.

5. The acoustic wave resonator structure according to claim 1 or 2, characterized in that: Define λ as the wavelength of the target sound wave, that is, the period of the interdigitated electrodes. When the thickness of the piezoelectric layer is h, the thickness of the polarization zone is 0.05λ-h; when the thickness of the piezoelectric single crystal substrate is T, the thickness of the polarization zone is 0.05λ-T.

6. The acoustic wave resonator structure according to claim 1 or 2, characterized in that: The boundary of the polarization region contacts the end of the aperture region.

7. The acoustic wave resonator structure according to claim 1 or 2, characterized in that: The piezoelectric layer corresponding to the first bus bar area and / or the second bus bar area also includes the polarization area; the polarization area corresponding to the first bus bar area and the polarization area corresponding to the second bus bar area are symmetrically or asymmetrically distributed.

8. The acoustic wave resonator structure according to claim 1 or 2, characterized in that: It also includes a first additional finger located in the first air gap region and a second additional finger located in the second air gap region, wherein the first additional finger is electrically connected to the first bus bar, and the second additional finger is electrically connected to the second bus bar.

9. An acoustic wave device, characterized in that: The acoustic wave device comprises an acoustic wave resonator structure as described in any one of claims 1 to 8; the acoustic wave device comprises at least one of a filter, a duplexer and a multiplexer.

10. A method for preparing an acoustic wave resonator structure as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Polarizing a part of the piezoelectric layer or the piezoelectric single crystal substrate to form the polarization region, and leaving an alignment mark; Based on the alignment mark, forming the patterned electrode on the piezoelectric layer; The preparation method of the polarization zone includes local bonding, local ion implantation, physical vapor deposition, chemical vapor deposition, magnetron sputtering or Czochralski crystal growth.

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