A SAW resonator of aluminum nitride-based heteroacoustic layer

Abstract

The application discloses a SAW resonator of an aluminum nitride-based heteroacoustic layer, and is used for improving resonator performance. The resonator comprises a heteroacoustic layer (HAL) structure, an input interdigital transducer (IDT), an output IDT, a first phononic crystal and a plurality of second phononic crystals. The HAL structure comprises a piezoelectric layer and a composite substrate, the piezoelectric material of the piezoelectric layer is scandium-doped aluminum nitride material. The input IDT and the output IDT are arranged on the piezoelectric layer respectively. The first phononic crystal is embedded into the piezoelectric layer and located between the input IDT and the output IDT, and is used for constructing a defect band through the first phononic crystal, so that the sound wave of the input IDT is propagated to the output IDT through the defect band. The input IDT comprises an input bus bar, and the output IDT comprises an output bus bar. The plurality of second phononic crystals are embedded into the piezoelectric layer respectively and located at two ends of the input bus bar and two ends of the output bus bar respectively, and are used for reflecting the sound wave through the second phononic crystals.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a SAW resonator with an aluminum nitride-based heterogeneous acoustic layer. Background Technology

[0002] SAW resonators, short for surface acoustic wave resonators, are specialized filtering devices that utilize the piezoelectric effect and the propagation properties of surface acoustic waves. The basic structure of an SAW resonator consists of two interdigital transducers (IDTs) fabricated on a polished surface of a piezoelectric substrate. These IDTs serve as the transmitting and receiving transducers, respectively. The transmitting IDT converts the electrical signal into an acoustic wave, which propagates across the surface of the SAW resonator substrate. The receiving IDT receives the acoustic wave and converts it back into an electrical signal, thus achieving filtering.

[0003] Currently, various novel SAW sensing systems based on SAW resonators are widely used, such as for sensing toxic gas environments, temperature sensing under high-temperature operating conditions, pressure sensing in extreme environments, tire pressure monitoring, and portable cancer diagnosis. Therefore, as the core component of SAW sensing systems, the performance of the SAW resonator directly affects the application performance of these systems. Among these factors, the quality factor (Q value) of the SAW resonator has the greatest impact and is the most important.

[0004] However, since most traditional SAW resonators use piezoelectric materials such as lithium niobate, lithium tantalate, quartz crystal, and piezoelectric ceramics as substrate materials, the Q value of SAW resonators is limited, and there is an urgent need to design a SAW resonator with higher Q value performance. Summary of the Invention

[0005] To address the aforementioned issues, this application provides an aluminum nitride-based heterogeneous acoustic layer SAW resonator for improving resonator performance.

[0006] The SAW resonator with aluminum nitride-based heterogeneous acoustic layer provided in this application includes:

[0007] The heterogeneous acoustic layer (HAL) structure includes an input IDT, an output IDT, a first reflective grating, a second reflective grating, a first phonon crystal, and several second phonon crystals.

[0008] The HAL structure includes a piezoelectric layer and a composite substrate, wherein the piezoelectric material of the piezoelectric layer is scandium-doped aluminum nitride.

[0009] The input IDT and the output IDT are respectively disposed on the piezoelectric layer;

[0010] The first reflective grating is disposed outside the input IDT, and the second reflective grating is disposed outside the output IDT, with the first reflective grating and the second reflective grating positioned opposite each other; the first phonon crystal is embedded in the piezoelectric layer and located between the input IDT and the output IDT, and is used to construct a defect band through the first phonon crystal, so that the sound wave of the input IDT propagates to the output IDT through the defect band;

[0011] The input IDT includes an input busbar, and the output IDT includes an output busbar;

[0012] The plurality of second phonon crystals are respectively embedded in the piezoelectric layer and are located at both ends of the input busbar and both ends of the output busbar, for reflecting sound waves through the second phonon crystals.

[0013] Optionally, the composite substrate includes a composite thin film and a supporting substrate;

[0014] The composite film includes a low-velocity layer and a high-velocity layer;

[0015] The upper surface of the low-velocity layer is connected to the piezoelectric layer, and the lower surface is sequentially connected to the high-velocity layer and the supporting substrate. The low-velocity layer and the high-velocity layer are used to confine sound waves to the piezoelectric layer and the low-velocity layer.

[0016] Optionally, the low-velocity layer is made of SiO2 material;

[0017] The hypersonic layer is made of aluminum nitride.

[0018] The supporting substrate is made of Si material.

[0019] Optionally, the thickness of the piezoelectric layer is 0.3λ;

[0020] The thickness of the low-velocity layer is 0.3λ;

[0021] The thickness of the hypersonic layer is 0.4λ;

[0022] The thickness dimension of the supporting substrate is 8λ, where λ is the wavelength.

[0023] Optionally, the input IDT further includes input electrodes;

[0024] The number of input busbars is two, and the two input busbars are respectively arranged on both sides of the input electrode;

[0025] The output IDT also includes output electrodes;

[0026] The number of output busbars is two, and the two output busbars are respectively arranged on both sides of the output electrode;

[0027] The first reflective grid and the second reflective grid are respectively disposed on the outside of the input electrode and the output electrode.

[0028] Optionally, the number of the second phonon crystals is four;

[0029] The four second phonon crystals are respectively disposed on the outside of the two input busbars and the two output busbars.

[0030] Optionally, the piezoelectric layer is made of Sc-doped AlScN single crystal material.

[0031] Optionally, the first phonon crystal and the second phonon crystal are microcavity arrays composed of a plurality of filling units.

[0032] Optionally, the filling unit is made of epoxy resin material.

[0033] Optionally, the filling unit is made of polystyrene material.

[0034] As can be seen from the above technical solutions, this application has the following advantages:

[0035] This application's SAW resonator includes a heterogeneous acoustic layer (HAL) structure, an input IDT, an output IDT, a first reflective grating, a second reflective grating, a first phonon crystal, and several second phonon crystals. The HAL structure includes a piezoelectric layer and a composite substrate. The piezoelectric material of the piezoelectric layer is scandium-doped aluminum nitride. The input IDT and output IDT are respectively disposed on the piezoelectric layer. The first reflective grating is disposed outside the input IDT, and the second reflective grating is disposed outside the output IDT, with the first and second reflective gratings positioned opposite each other. The first phonon crystal is embedded in the piezoelectric layer and located between the input IDT and the output IDT, used to construct a defect band through the first phonon crystal, allowing the sound waves from the input IDT to propagate to the output IDT through the defect band. The input IDT includes an input busbar, and the output IDT includes an output busbar. Several second phonon crystals are respectively embedded in the voltage layer and located at both ends of the input busbar and the output busbar, used to reflect sound waves through the second phonon crystals.

[0036] In this application, scandium-doped aluminum nitride possesses characteristics such as high thermal conductivity, high hardness, high melting point, high chemical stability, and low coefficient of thermal expansion. Therefore, as a piezoelectric material, scandium-doped aluminum nitride can significantly improve the propagation speed of surface acoustic waves (SAWs). Furthermore, a first phonon crystal is constructed between the input IDT and the output IDT to create a defect band, guiding the sound wave to propagate through the defect band between the two IDTs and reducing the spillover of sound wave energy. Simultaneously, second phonon crystals are distributed on both sides of the busbar, utilizing the bandgap characteristics of acoustic waves to reflect the spilled sound wave energy, thereby reducing lateral leakage of sound wave energy and improving the effective propagation of sound waves from the input IDT to the output IDT. This, in turn, increases the Q value of the entire SAW resonator and enhances its performance. Attached Figure Description

[0037] Figure 1 A schematic diagram of the three-dimensional structure of the SAW resonator with an aluminum nitride-based heterogeneous acoustic layer provided in this application;

[0038] Figure 2 A front view schematic diagram of the SAW resonator with an aluminum nitride-based heterogeneous acoustic layer provided in this application;

[0039] Figure 3 This is a top view schematic diagram of the SAW resonator with an aluminum nitride-based heterogeneous acoustic layer provided in this application. Detailed Implementation

[0040] This application provides an aluminum nitride-based heterogeneous acoustic layer SAW resonator for improving the Q value of the SAW resonator, thereby improving the performance of the SAW resonator.

[0041] In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and other terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to describe the relative positional relationship between the components or parts and do not specifically limit the specific installation orientation of each component or part.

[0042] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0043] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0044] Furthermore, the structures, proportions, sizes, etc., drawn in the accompanying drawings of this application are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0045] Furthermore, the terms “first,” “second,” “third,” etc., as used in this application (if applicable), are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments described in this application can be implemented in a sequence other than that illustrated or described herein.

[0046] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] Please see Figures 1 to 3 The SAW resonator with aluminum nitride heterostructure acoustic layer provided in this application includes:

[0048] The heterogeneous acoustic layer (HAL) structure 1 comprises an input IDT 2, an output IDT 3, a first reflective grating 6, a second reflective grating 7, a first phonon crystal 4, and several second phonon crystals 5. The HAL structure 1 includes a piezoelectric layer 11 and a composite substrate. The piezoelectric material of the piezoelectric layer 11 is scandium-doped aluminum nitride. The input IDT 2 and output IDT 3 are respectively disposed on the piezoelectric layer 11. The first reflective grating 6 is disposed outside the input IDT 2, and the second reflective grating 7 is disposed outside the output IDT 3, with the first reflective grating 6 and the second reflective grating 7 positioned opposite each other. A first phonon crystal 4 is embedded in the piezoelectric layer 11 and located between the input IDT2 and the output IDT3. It is used to construct a defect band through the first phonon crystal 4, so that the sound wave of the input IDT2 can propagate to the output IDT3 through the defect band. The input IDT2 includes an input bus bar 21, and the output IDT3 includes an output bus bar 31. A plurality of second phonon crystals 5 are embedded in the piezoelectric layer 11 and located at both ends of the input bus bar 21 and the output bus bar 31, respectively, for reflecting sound waves through the second phonon crystals 5.

[0049] In this embodiment, the hetero acoustic layer (HAL) structure includes a piezoelectric layer 11 and a composite substrate. The piezoelectric layer 11 can be made of an aluminum nitride (AlN)-based material, such as aluminum nitride, scandium-doped (Sc) aluminum nitride, or chromium-doped (Ge) aluminum nitride. In this embodiment, the piezoelectric layer 11 is specifically made of scandium-doped (Sc) aluminum nitride. The composite substrate is located below the piezoelectric layer 11. This composite substrate can be configured as a composite support substrate with high acoustic energy confinement characteristics, thereby confining acoustic energy within the piezoelectric layer 11 as much as possible and reducing acoustic energy leakage. For example, the composite substrate can be configured as a Bragg reflector layer structure or a high / low sound velocity layer structure, or other structures, which are not limited here.

[0050] Input IDT2 and output IDT3 are respectively disposed at both ends of the upper surface of piezoelectric layer 11, on the outer side of input IDT2 (i.e., Figure 1 A first reflective grating 6 is provided on the left side of the input IDT2 (as shown), and on the outer side of the output IDT2 away from the input IDT (i.e. Figure 1A second reflective grating 7 is provided on the right side of the output IDT3 (shown). The first reflective grating 6 and the second reflective grating 7 are used to reflect the acoustic wave energy transmitted from the input IDT2 and the output IDT3, respectively. Furthermore, a first phonon crystal 4 embedded in the piezoelectric layer 11 is placed between the input IDT2 and the output IDT3. Generally, a phonon crystal is an artificial crystal with elastic constants arranged periodically in space. It possesses waveguide characteristics that allow acoustic waves of specific frequencies to propagate. That is, during operation, elastic waves within a certain bandgap range are suppressed when propagating in the phonon crystal, while elastic waves in other frequency ranges can propagate. Therefore, when setting the periodically arranged first phonon crystal 4, the waveguide characteristics of the phonon crystal can be utilized to artificially design a regularly occurring defect band from the input IDT2 to the output IDT3 within the periodic structure. This allows elastic waves that would otherwise be unable to propagate within the bandgap frequency range to effectively propagate from the input IDT2 to the output IDT3 through the defect band. This improves the effective propagation of acoustic wave energy in the resonator by confining the acoustic wave energy within the bandgap frequency band to propagate within the defect band of the first phonon crystal 4.

[0051] Furthermore, since input IDT2 and output IDT3 each have their corresponding input busbar 21 and output busbar 31, second phonon crystals 5 can be respectively disposed on the outside of input busbar 21 and output busbar 31. Utilizing the propagation characteristics of sound waves in a specific frequency band being strongly reflected and unable to propagate in the phonon crystal, the periodic structure of the second phonon crystal 5 is artificially designed and adjusted so that the second phonon crystal 5 can reflect the sound waves leaking from input IDT2 or output IDT3, thereby reducing sound wave leakage and confining the sound wave energy within the piezoelectric layer 11 as much as possible.

[0052] In this embodiment, a piezoelectric layer 11 made of aluminum nitride is first provided. Aluminum nitride possesses high thermal conductivity, high hardness, high melting point, high chemical stability, and a low coefficient of thermal expansion, thereby increasing the propagation speed of surface acoustic waves (SAWs). Then, a composite substrate is placed below the piezoelectric layer 11 to confine the sound waves within the piezoelectric layer 11 as much as possible, reducing longitudinal energy leakage. Simultaneously, a first phonon crystal 4 is placed in the input IDT2 and output IDT3 to construct a defect band that allows SAWs to propagate along the defect band. Furthermore, a second phonon crystal 5 is placed outside the input busbar 21 and output busbar 31 to reflect SAWs. Therefore, during operation, after the input IDT2 converts the electrical signal into a sound wave, the sound wave is constrained by the composite substrate, the first phonon crystal 4, and the second phonon crystal 5, propagating along the defect band of the first phonon crystal 4 to the output IDT3. The output IDT3 then converts the received sound wave back into an electrical signal for output. The entire process achieves lateral and longitudinal constraint on the sound wave, reducing the loss of sound wave energy, thereby improving the Q value of the SAW resonator and enhancing its performance.

[0053] Optionally, the composite substrate includes a composite thin film 12 and a supporting substrate 13; the composite thin film 12 includes a low-velocity layer 121 and a high-velocity layer 122; the upper surface of the low-velocity layer 121 is connected to a piezoelectric layer 11, and the lower surface is sequentially connected to the high-velocity layer 122 and the supporting substrate 13, and the low-velocity layer 121 and the high-velocity layer 122 are used to confine sound waves within the piezoelectric layer 11 and the low-velocity layer 121.

[0054] In this embodiment, a composite substrate consisting of a low-velocity layer 121, a high-velocity layer 122, and a supporting substrate 13 is disposed below the piezoelectric layer 11. It should be noted that the velocity of sound in the low-velocity layer 121 is relative to that in the high-velocity layer 122; that is, the propagation velocity of sound in the low-velocity layer 121 is lower than that in the high-velocity layer 122. Therefore, in this embodiment, the characteristic that sound waves propagating at the interface between the high-velocity layer 122 and the low-velocity layer 121 are drawn to the low-velocity layer 121 can be utilized to confine the sound waves within the low-velocity layer 121 and the piezoelectric layer 11 above, reducing leakage of sound waves to the supporting substrate 13 below, thereby reducing the loss of sound wave energy.

[0055] Optionally, the low-velocity layer 121 is made of SiO2 material; the high-velocity layer 122 is made of aluminum nitride material; and the support substrate 13 is made of Si material.

[0056] In this embodiment, the high electromechanical coupling coefficient, high sound velocity, and low loss characteristics of AlN material are utilized to construct a high sound velocity layer 122. Simultaneously, a low sound velocity layer 121 is constructed using SiO2 material. This allows the high and low sound velocity characteristics of AlN-SiO2- to almost completely concentrate the sound waves on the surface of the piezoelectric layer 11, resulting in a high Q value for the SAW resonator and improving its performance.

[0057] Optionally, the piezoelectric layer 11 has a thickness of 0.3λ; the low-velocity layer 121 has a thickness of 0.3λ; the high-velocity layer 122 has a thickness of 0.4λ; and the supporting substrate 13 has a thickness of 8λ, where λ is the wavelength.

[0058] In this embodiment, the piezoelectric layer 11 is an AlN thin film with a thickness of 0.3λ, the low-velocity layer 121 is a SiO2 thin film with a thickness of 0.3λ, the high-velocity layer 122 is an AlN thin film with a thickness of 0.4λ, and the supporting substrate 13 is made of Si material with a thickness of 8λ. By using SiO2-AlN to construct the low-velocity layer 121 and the high-velocity layer 122, and adding Si as the supporting substrate 13, a reflective layer can be formed effectively, better confining the sound waves within the piezoelectric layer 11 and the low-velocity layer 121, thus reducing the energy loss of the resonator in the depth direction. It should be noted that the thickness and material of each layer of the resonator can be designed with other dimensions and materials according to the actual application of the resonator; specific limitations are not specified here.

[0059] Optionally, the input IDT2 further includes an input electrode 22; the number of input busbars 21 is two, and the two input busbars 21 are respectively disposed on both sides of the input electrode 22; the output IDT3 further includes an output electrode 32; the number of output busbars 31 is two, and the two output busbars 31 are respectively disposed on both sides of the output electrode 32; the first reflective grid 6 and the second reflective grid 7 are respectively disposed on the outside of the input electrode 22 and the output electrode 32.

[0060] In this embodiment, the input IDT2 specifically includes an input electrode 22 and two input busbars 21; the output IDT3 specifically includes an output electrode 32 and two output busbars 31. The input IDT2 and output IDT3 are disposed on the upper surface of the piezoelectric layer 11, and are located at opposite ends of this upper surface. Specifically, the two input busbars 21 are respectively located above and below the input electrode 22, partially surrounding it, and a first reflective grating 6 is disposed on the left side of the input electrode 22 for reflecting sound waves. Similarly, the two output busbars 31 are respectively disposed above and below the output electrode 32, and a second reflective grating 7 is disposed on the right side of the output electrode 32. Furthermore, second phonon crystals 5 are disposed on the outer sides of the input busbars 21 and the output busbars 31 for reflecting sound waves.

[0061] During operation, the electrical signal input to IDT2 is converted into a sound wave. The sound wave propagates through the first phonon crystal 4 within the piezoelectric layer 11 to the output IDT3. At this time, due to the reflection of the sound wave by the first reflective grating 6, the second phonon crystal 5, and the second reflective grating 7, the sound wave propagates effectively between the input IDT2, the first phonon crystal 4, and the output IDT3, which can reduce the leakage loss of the sound wave and improve the resonator performance.

[0062] Optionally, the number of the second phonon crystals 5 is four; the four second phonon crystals 5 are respectively disposed on the outside of the two input busbars 21 and the two output busbars 31.

[0063] In this embodiment, four second phonon crystals 5 can be set. Each second phonon crystal 5 is set on the outside of the busbar to reflect the sound waves on the outside of the busbar and concentrate the sound wave energy on the inside of the busbar and the first phonon crystal 4 for propagation, thereby reducing the lateral leakage of sound wave energy.

[0064] Optionally, the piezoelectric layer 11 is made of Sc-doped AlScN single crystal material.

[0065] In this embodiment, to achieve high frequency and low insertion loss in SAW resonators, it is necessary to continuously improve the piezoelectric properties of piezoelectric materials. Since Sc-doped AlN piezoelectric films have significantly improved piezoelectric properties compared to AlN piezoelectric films, Sc-doped AlN materials can be used as the material for piezoelectric layer 11 to improve the performance of SAW resonators.

[0066] Optionally, the first phonon crystal 4 and the second phonon crystal 5 are microcavity arrays composed of a plurality of filling units.

[0067] In this embodiment, the first phonon crystal 4 and the second phonon crystal 5 are periodically arranged artificial crystals, specifically a microcavity array composed of multiple periodically arranged filling units. Each filling unit is made of waveguide material and embedded in the piezoelectric layer 11, used to reflect and confine or propagate elastic waves through the waveguide material. It should be noted that the structure of the periodically arranged microcavity array composed of these filling units can be designed and controlled artificially. By adjusting the periodic structure, the phonon crystals formed by it can reflect or propagate sound waves, thereby achieving the purpose of confining sound energy.

[0068] Alternatively, the filling unit may be made of shape memory alloy (SMA), epoxy resin material, or polystyrene material.

[0069] In this embodiment, the waveguide material of the filling unit can be made of shape memory alloy (SMA), epoxy resin, or polystyrene. This reduces the possibility of total internal reflection of sound waves in the microcavity array of the phononic crystal due to excessive acoustic impedance. Simultaneously, it allows the propagation speed of the waveguide material in the filling unit to be close to or less than the sound speed of the piezoelectric layer 11, improving the confinement of acoustic energy. It should be noted that the filling unit can also be made of other waveguide materials; specific methods are not limited here.

[0070] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A SAW resonator with an aluminum nitride-based heterogeneous acoustic layer structure, characterized in that, The SAW resonator includes: The heterogeneous acoustic layer (HAL) structure includes an input interdigital transducer (IDT), an output IDT, a first reflective grating, a second reflective grating, a first phonon crystal, and several second phonon crystals. The HAL structure includes a piezoelectric layer and a composite substrate, wherein the piezoelectric material of the piezoelectric layer is scandium-doped aluminum nitride. The input IDT and the output IDT are respectively disposed on the piezoelectric layer; The first reflective grating is disposed outside the input IDT, and the second reflective grating is disposed outside the output IDT, with the first reflective grating and the second reflective grating being positioned opposite each other; The first phonon crystal is embedded in the piezoelectric layer and located between the input IDT and the output IDT, and is used to construct a defect band through the first phonon crystal so that the sound wave of the input IDT can propagate to the output IDT through the defect band; The input IDT includes an input busbar, and the output IDT includes an output busbar; The plurality of second phonon crystals are respectively embedded in the piezoelectric layer and are located at both ends of the input busbar and both ends of the output busbar, for reflecting sound waves through the second phonon crystals.

2. The SAW resonator according to claim 1, characterized in that, The composite substrate includes a composite thin film and a supporting substrate; The composite film includes a low-velocity layer and a high-velocity layer; The upper surface of the low-velocity layer is connected to the piezoelectric layer, and the lower surface is sequentially connected to the high-velocity layer and the supporting substrate. The low-velocity layer and the high-velocity layer are used to confine sound waves within the piezoelectric layer and the low-velocity layer.

3. The SAW resonator according to claim 2, characterized in that, The low-velocity layer is made of SiO2 material; The hypersonic layer is made of aluminum nitride. The supporting substrate is made of Si material.

4. The SAW resonator according to claim 3, characterized in that, The thickness of the piezoelectric layer is 0.

3. ; The thickness of the low-velocity layer is 0.

3. ; The thickness of the hypersonic layer is 0.

4. ; The thickness of the supporting substrate is 8 ,in λ is the wavelength.

5. The SAW resonator according to any one of claims 1 to 4, characterized in that, The input IDT also includes input electrodes; The number of input busbars is two, and the two input busbars are respectively arranged on both sides of the input electrode; The output IDT also includes output electrodes; The number of output busbars is two, and the two output busbars are respectively arranged on both sides of the output electrode; The first reflective grid and the second reflective grid are respectively disposed on the outside of the input electrode and the output electrode.

6. The SAW resonator according to claim 5, characterized in that, The number of the second phonon crystals is 4; The four second phonon crystals are respectively disposed on the outside of the two input busbars and the two output busbars.

7. The SAW resonator according to any one of claims 1 to 4, characterized in that, The piezoelectric layer is made of Sc-doped AlScN single crystal material.

8. The SAW resonator according to any one of claims 1 to 4, characterized in that, The first phonon crystal and the second phonon crystal are microcavity arrays composed of a number of filling units.

9. The SAW resonator according to claim 8, characterized in that, The filling unit is made of epoxy resin material.

10. The SAW resonator according to claim 8, characterized in that, The filling unit is made of polystyrene material.

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