Acoustic wave resonator and filter

Abstract

The present application relates to the technical field of radio frequency, and discloses an acoustic wave resonator and a filter. The acoustic wave resonator comprises a substrate, a coupling adjustment layer, a piezoelectric layer, and interdigital electrodes. By selecting the material of the piezoelectric layer and the tangential direction of the material, and setting the value range of an in-plane Euler angle α, a piezoelectric coefficient of the piezoelectric layer comprises an e11 component and an e34 component in a piezoelectric coefficient matrix, such that an acoustic wave excited in the piezoelectric layer at least comprises a longitudinal mode acoustic wave mainly excited by the e11 component and a higher-order shear mode acoustic wave mainly excited by the e34 component; and by providing the coupling adjustment layer made of a suitable material and having a suitable thickness ratio to the piezoelectric layer, the resonance of the longitudinal mode acoustic wave and the higher-order shear mode acoustic wave are tuned to the same frequency, so as to achieve coupling, and finally, an acoustic wave comprising two mutually orthogonally polarized coupled modes in a specific propagation direction is excited. The requirements of a centimeter wave communication frequency band for a high frequency and a large bandwidth are met. The device has a simple structure, and the manufacturing complexity and costs of the device can be reduced.

Description

An acoustic resonator and filter

[0001] This application claims priority to Chinese Patent Application No. 202411806913.2, filed on December 9, 2024, entitled "An Acoustic Wave Resonator and Filter", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of radio frequency technology, and in particular to an acoustic resonator and a filter. Background Technology

[0003] Currently, 5G communication technology is in a phase of rapid development. Simultaneously, with the market's urgent demand for higher data transmission rates, Wi-Fi 7 technology has also emerged. The various frequency bands used by 5G and Wi-Fi 7 not only have higher center frequencies but also wider bandwidths. For example, 5G's n77 band covers a frequency range of 3.3GHz to 4.2GHz, with a bandwidth of 900MHz and a relative bandwidth (FBW) of 24%; Wi-Fi 7's UNII 5-8 band operates in a frequency range of 5.925GHz to 7.125GHz, with a bandwidth reaching 1200MHz and a relative bandwidth as high as 18.4%. The introduction of these high-frequency, wideband frequency bands significantly improves the performance of communication systems, but also places higher technical demands on the signal processing capabilities of the radio frequency front-end (RFFE) to ensure high-speed and high-reliability data transmission.

[0004] Radio frequency (RF) filters are indispensable components in RF front-ends, among which acoustic wave (AWB) filters are among the most popular due to their advantages such as small size, high frequency, low insertion loss, and large bandwidth. However, with the continuous increase in operating frequency, AFB filters face increasingly stringent performance challenges. For example, as mentioned above, in the UNII 5-8 band (5.925GHz-7.125GHz) of Wi-Fi 7, the required relative bandwidth (FBW) exceeds 18.4%, which requires the electromechanical coupling coefficient (k2) of the AFB resonator to reach at least 36.8%. However, traditional AFB resonators can no longer meet the current demand for high performance. For example, thin-film bulk acoustic resonators (FBARs) have encountered significant technical limitations in expanding the relative bandwidth; while Lamb wave AFB resonators can achieve both high operating frequencies and wide bandwidths, their reliance on the vibration characteristics of the suspension structure leads to problems with device structural stability. In addition, their fabrication process is complex and costly. Therefore, improving the performance of AFB resonators operating in the centimeter-wave band while reducing device fabrication complexity and cost has become a technical challenge that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, embodiments of this application provide an acoustic resonator and a filter to improve the performance of the acoustic resonator operating in the centimeter-wave frequency band, while reducing the complexity and cost of device fabrication.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0007] An acoustic resonator, comprising:

[0008] Substrate;

[0009] A coupling adjustment layer located on one side of the substrate;

[0010] A piezoelectric layer located on the side of the coupling adjustment layer away from the substrate, wherein the piezoelectric layer is made of anisotropic piezoelectric material and the tangential direction of the piezoelectric material is a preset tangential direction;

[0011] The interdigitated electrode is located on the side of the piezoelectric layer away from the substrate. The extension direction of the interdigitated electrode is a first direction, and the second direction is perpendicular to the first direction. Both the first direction and the second direction are parallel to the plane of the piezoelectric layer.

[0012] The angle between the second direction and the positive c-axis in the coordinate system of the preset tangent is taken as the in-plane Euler angle α of the piezoelectric material, where the c-axis is parallel to the plane of the piezoelectric layer; the Euler angle α takes the value of a preset range, such that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix. 11 Components and e 34 The components, the piezoelectric coefficient matrix is ​​represented as:

[0013] Wherein, the e 11 The component is used to excite longitudinal modal acoustic waves, the e 34 The component is used to excite higher-order shear mode acoustic waves.

[0014] Optionally, the piezoelectric layer is a lithium niobate layer, or a lithium tantalate layer, or a composite layer composed of at least two of the following: a lithium niobate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, a lithium tantalate layer, and a zinc oxide layer.

[0015] The thickness of the piezoelectric layer ranges from 10 nm to 5000 nm, including the endpoint values.

[0016] Optionally, the coupling adjustment layer is a silicon dioxide layer, or a silicon layer, or a polycrystalline silicon layer, or a silicon nitride layer, or a sapphire layer, or a composite layer composed of at least two of the following: silicon dioxide layer, silicon layer, polycrystalline silicon layer, silicon nitride layer and sapphire layer.

[0017] The thickness of the coupling adjustment layer ranges from 10nm to 5000nm, including the endpoint values.

[0018] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent is the X-tangent, the c-axis in the coordinate system of the X-tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X-tangent is taken as the Euler angle α.

[0019] The Euler angle α satisfies: 10°≤α≤90°, or -170°≤α≤-90°.

[0020] Optionally, the sound velocity of the coupling modulation layer characterizes the phase velocity of the sound wave propagating in the coupling modulation layer, and the sound velocity v of the coupling modulation layer is expressed as:

[0021] Where E is the Young's modulus of the material of the coupling adjustment layer, and ρ is the density of the material of the coupling adjustment layer;

[0022] The sound velocity v of the coupling adjustment layer satisfies: 1000m / s≤v≤15600m / s, including the endpoint value.

[0023] Optionally, the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo Satisfying: 3% ≤ h med / h piezo ≤100%.

[0024] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent is the X-tangent, the c-axis in the coordinate system of the X-tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X-tangent is taken as the Euler angle α.

[0025] The coupling adjustment layer is a silicon dioxide layer, and the sound velocity of the coupling adjustment layer is v = 5640.8 m / s;

[0026] When the Euler angle α = 39°, the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo = 4.5%, 12.5%, 20%, 60%, or 100%;

[0027] When the Euler angle α = 55°, the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo =12.5%.

[0028] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent is the X-tangent, the c-axis in the coordinate system of the X-tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X-tangent is taken as the Euler angle α.

[0029] The coupling adjustment layer is a polycrystalline silicon layer, and the sound velocity of the coupling adjustment layer is v = 8304.5 m / s;

[0030] The Euler angle α = 40°, and the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo =26.25%.

[0031] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent is the X-tangent, the c-axis in the coordinate system of the X-tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X-tangent is taken as the Euler angle α.

[0032] The coupling adjustment layer is a silicon nitride layer, and the sound velocity of the coupling adjustment layer is v = 8980.3 m / s;

[0033] The Euler angle α = 40°, and the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo =36.25%.

[0034] A filter comprising the acoustic resonator described in any of the preceding claims.

[0035] Compared with existing technologies, the above technical solution has the following advantages:

[0036] The acoustic resonator provided in this embodiment includes a substrate and a coupling adjustment layer, a piezoelectric layer, and interdigitated electrodes sequentially disposed on one side of the substrate. The extension direction of the interdigitated electrodes is a first direction, and a second direction is perpendicular to the first direction. Both the first and second directions are parallel to the plane of the piezoelectric layer. The piezoelectric layer is made of anisotropic piezoelectric material, and the tangent of the piezoelectric material is a preset tangent. The angle between the second direction and the positive c-axis in the coordinate system of the preset tangent is taken as the in-plane Euler angle α of the piezoelectric material. The c-axis is parallel to the plane of the piezoelectric layer, and the value range of the Euler angle α is set to a preset range, so that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix. 11 Components and e 34 Components, where e 11 The component is used to excite longitudinal modal acoustic waves, e 34The component is used to excite higher-order shear mode acoustic waves, thus the acoustic waves excited by the piezoelectric layer include at least longitudinal mode acoustic waves and higher-order shear mode acoustic waves. Although the longitudinal mode acoustic waves and higher-order shear mode acoustic waves excited by the piezoelectric layer alone are independent of each other and resonate at different frequencies, after the introduction of the coupling modulation layer, since the coupling modulation layer also participates in mechanical vibration, the equivalent sound velocity (i.e., the phase velocity of sound wave propagation) of the whole composed of the piezoelectric layer and the coupling modulation layer changes relative to the sound velocity of a single piezoelectric layer. That is, the introduction of the coupling modulation layer can change the sound velocity of the sound wave. Furthermore, since the vibration displacements of the longitudinal mode acoustic waves and higher-order shear mode acoustic waves penetrate to different depths into the piezoelectric layer and the coupling modulation layer, the coupling modulation layer affects the two modes of the longitudinal mode acoustic waves and higher-order shear mode acoustic waves. The speed of sound affects the frequency of sound waves differently, and the resonant frequency of a sound wave is determined by the speed of sound. Therefore, by setting a suitable material and a coupling adjustment layer with a suitable thickness ratio to the piezoelectric layer, the resonance of the longitudinal mode sound wave and the higher-order shear mode sound wave can be adjusted to the same frequency, achieving the coupling of these two modes of sound waves. Ultimately, sound waves including two mutually orthogonally polarized coupled modes under a specific propagation direction are excited, realizing the dynamic adjustment of the operating frequency and electromechanical coupling coefficient of the sound wave resonator. This meets the high frequency and large bandwidth requirements of the sound wave resonator in the centimeter wave communication band. Furthermore, the structural design of the sound wave resonator is simple, which can also reduce the complexity and cost of device fabrication. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 is a schematic cross-sectional view of an acoustic resonator provided in an embodiment of this application.

[0039] Figure 2a is a schematic diagram of the in-plane Euler angle α of the piezoelectric material constituting the piezoelectric layer in a coordinate system with the preset tangent direction X.

[0040] Figure 2b is a schematic diagram of the in-plane Euler angle α of the piezoelectric material constituting the piezoelectric layer in a coordinate system with the preset tangent direction of Y.

[0041] Figure 2c is a schematic diagram of the in-plane Euler angle α of the piezoelectric material constituting the piezoelectric layer in a coordinate system with the preset tangent direction Z.

[0042] Figure 3 is a partial cross-sectional structural diagram of another acoustic resonator provided in an embodiment of this application;

[0043] Figure 4 is a simulation admittance curve of the acoustic resonator of Embodiment 1 of this application operating at 6GHz;

[0044] Figure 5 is a simulation admittance curve of the acoustic resonator of Embodiment 2 of this application operating at 6GHz;

[0045] Figure 6 is a simulation admittance curve of the acoustic resonator of Embodiment 3 of this application operating at 8GHz;

[0046] Figure 7 is a simulated admittance curve of the acoustic resonator of Embodiment 4 of this application operating at 15.5 GHz;

[0047] Figure 8 is a simulation admittance curve of the acoustic resonator of Embodiment 5 of this application operating at 2GHz;

[0048] Figure 9 is a simulation admittance curve of the acoustic resonator of Embodiment 6 of this application operating at 4GHz;

[0049] Figure 10 is a simulation admittance curve of the acoustic resonator of Embodiment 7 of this application operating at 6GHz;

[0050] Figure 11 is a simulation admittance curve of the acoustic resonator of Embodiment 8 of this application operating at 6GHz;

[0051] Figure 12 is a simulation admittance curve of the acoustic resonator of Embodiment 9 of this application operating at 6GHz;

[0052] Figure 13 is a partial cross-sectional structural diagram of another acoustic resonator provided in an embodiment of this application. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below 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.

[0054] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0055] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0056] This application provides an acoustic resonator. Figure 1 shows a cross-sectional structural schematic diagram of an acoustic resonator provided in this application. As shown in Figure 1, the acoustic resonator includes a substrate 1, a coupling adjustment layer 2 located on one side of the substrate 1, a piezoelectric layer 3 located on the side of the coupling adjustment layer 2 away from the substrate 1, and interdigitated electrodes 4 located on the side of the piezoelectric layer 3 away from the substrate 1.

[0057] Among them, the material of the piezoelectric layer 3 is an anisotropic piezoelectric material, and the tangential direction of the piezoelectric material is a preset tangential direction.

[0058] We know that the tangent of a piezoelectric material refers to the direction parallel to the normal of the cutting surface after a piezoelectric material is cut with a cutting surface. The choice of the tangent of a piezoelectric material has an important influence on the performance and application of the piezoelectric material. After the tangent of the piezoelectric material is determined, the thickness direction of the piezoelectric layer composed of the piezoelectric material is determined. Furthermore, the coordinate axes along the thickness direction of the piezoelectric layer in the coordinate system of the determined tangent are also determined. In the coordinate system of the determined tangent, the other two coordinate axes are parallel to the plane where the piezoelectric layer is located, that is, the coordinate system of the determined tangent can also be determined.

[0059] For example, if the preset tangential direction of the piezoelectric material constituting the piezoelectric layer 3 is the X-tangential direction, then in the X-tangential coordinate system, as shown in Figures 1 and 2a, the X-axis is parallel to the thickness direction of the piezoelectric layer 3, the Y-axis and Z-axis are parallel to the plane where the piezoelectric layer 3 is located, and the X-axis, Y-axis and Z-axis are perpendicular to each other.

[0060] For example, if the preset tangential direction of the piezoelectric material constituting the piezoelectric layer 3 is the Y-axis, then in the Y-axis coordinate system, as shown in Figures 1 and 2b, the Y-axis is parallel to the thickness direction of the piezoelectric layer 3, the X-axis and Z-axis are parallel to the plane where the piezoelectric layer 3 is located, and the X-axis, Y-axis and Z-axis are perpendicular to each other.

[0061] For example, if the preset tangential direction of the piezoelectric material constituting the piezoelectric layer 3 is the Z-tangential direction, then in the coordinate system of the Z-tangential direction, as shown in Figures 1 and 2c, the Z-axis is parallel to the thickness direction of the piezoelectric layer 3, the X-axis and Y-axis are parallel to the plane where the piezoelectric layer 3 is located, and the X-axis, Y-axis and Z-axis are perpendicular to each other.

[0062] In this application, as shown in Figures 1 and 2a-2c, the extension direction of the interdigital electrode 4 is set as the first direction M, the second direction N is perpendicular to the first direction M, and both the first direction M and the second direction N are parallel to the plane where the piezoelectric layer 3 is located.

[0063] Understandably, the second direction N is parallel to the direction of the horizontal electric field formed by the interdigital electrode 4. We know that interdigital electrodes usually form finger-shaped or comb-shaped electrode pairs, which form a periodic pattern on a horizontal plane. When a voltage is applied to the interdigital electrodes, an electric field is formed between the interdigital electrodes. Between adjacent interdigital electrodes, the direction of the electric field is usually horizontal, perpendicular to the extension direction of the interdigital electrodes, and the direction of the electric field alternates along the horizontal direction.

[0064] In this application, the angle between the second direction N and the positive direction of the c-axis in the coordinate system of the preset tangential direction of the piezoelectric material constituting the piezoelectric layer 3 is taken as the in-plane Euler angle α of the piezoelectric material. The c-axis is parallel to the plane where the piezoelectric layer 3 is located and is a coordinate axis parallel to the plane where the piezoelectric layer 3 is located in the preset tangential coordinate system.

[0065] For example, as shown in Figure 2a, the preset tangent of the piezoelectric material constituting the piezoelectric layer 3 is the X-tangent, and the angle between the second direction N and the positive Y-axis in the coordinate system of the X-tangent is taken as the in-plane Euler angle α of the piezoelectric material, that is, the c-axis in the coordinate system of the X-tangent is the Y-axis.

[0066] For example, as shown in Figure 2b, the preset tangent of the piezoelectric material constituting the piezoelectric layer 3 is the Y-tangent. The angle between the second direction N and the positive X-axis in the coordinate system of the Y-tangent is taken as the in-plane Euler angle α of the piezoelectric material, that is, the c-axis in the coordinate system of the Y-tangent is the X-axis.

[0067] For example, as shown in Figure 2c, the preset tangent of the piezoelectric material constituting the piezoelectric layer 3 is the Z tangent, and the angle between the second direction N and the positive X-axis in the coordinate system of the Z tangent is taken as the in-plane Euler angle α of the piezoelectric material, that is, the c-axis in the coordinate system of the Y tangent is the X-axis.

[0068] A suitable anisotropic piezoelectric material can be selected, along with a suitable tangent, thereby allowing the Euler angle α to be chosen within a preset range. This ensures that the piezoelectric coefficient of piezoelectric layer 3 includes the e in the piezoelectric coefficient matrix. 11 Components and e 34 Components, where e 11 The component is used to excite longitudinal modal acoustic waves, e 34 The component is used to excite higher-order shear mode acoustic waves.

[0069] Understandably, the piezoelectric coefficient matrix of a piezoelectric material represents its performance in the electromechanical conversion process. It reveals the relationship between the amount of charge generated in each direction and the stress when the piezoelectric material is subjected to stress. Because the electric field is a vector (with three directions), and stress is a second-order tensor (with six independent components, including three normal stresses and three shear stresses), the piezoelectric coefficient matrix of a piezoelectric material can be represented as a 3×6 matrix.

[0070] The elements in the piezoelectric coefficient matrix are represented as e. ij , where i represents the direction of the electric field and j represents the direction of the stress. In the piezoelectric coefficient matrix above, the first three columns are the longitudinal piezoelectric coefficients, and the last three columns are the shear piezoelectric coefficients. The piezoelectric coefficient matrix is ​​an inherent physical property of piezoelectric materials, and the values ​​of the elements in the piezoelectric coefficient matrix depend on the type of piezoelectric material, the tangential direction, and the in-plane Euler angles.

[0071] In the acoustic resonator structure proposed in this application, once the piezoelectric material and its tangent of the piezoelectric layer 3 are determined, the elements in the piezoelectric coefficient matrix change with the rotation of the in-plane Euler angle α. Once the Euler angle α is determined, the piezoelectric coefficient matrix of the piezoelectric layer 3 is also determined.

[0072] It is also understandable that the excitation of a specific acoustic mode is closely related to the type, tangent, and in-plane Euler angle α of the piezoelectric material in piezoelectric layer 3. Once the piezoelectric material and tangent of piezoelectric layer 3 are determined, different in-plane Euler angles α will result in different types and numbers of piezoelectric coefficients for the excited acoustic modes. Therefore, by determining the type, tangent, and in-plane Euler angle α of the piezoelectric material in piezoelectric layer 3, the piezoelectric coefficients of the excited acoustic modes in piezoelectric layer 3 can be made to include the ep in the piezoelectric coefficient matrix. 11 Components and e 34 Component, e 11 The component is used to excite longitudinal modal acoustic waves, e 34 The component is used to excite higher-order shear mode acoustic waves.

[0073] Optionally, the piezoelectric layer 3 can be a lithium niobate layer, a lithium tantalate layer, or a composite layer composed of at least two layers selected from lithium niobate, aluminum nitride, scandium-doped aluminum nitride, lithium tantalate, and zinc oxide. For piezoelectric layers 3 made of different piezoelectric materials, specific tangential directions and in-plane Euler angle α values ​​can be selected accordingly, such that the piezoelectric coefficient of the acoustic mode excited by the piezoelectric layer 3 includes the e in the piezoelectric coefficient matrix. 11 Components and e 34 Quantity.

[0074] For example, piezoelectric layer 3 is a lithium niobate layer, with the preset tangential direction being the X-tangential direction. As previously known, as shown in Figure 2a, the c-axis in the X-tangential coordinate system is the Y-axis, that is, the angle between the second direction N and the positive Y-axis in the X-tangential coordinate system is taken as the Euler angle α. The lithium niobate layer in the X-tangential direction has strong anisotropy. When the in-plane Euler angle α takes different values, the types and number of piezoelectric coefficients of the acoustic modes excited by piezoelectric layer 3 are also different. When the Euler angle α satisfies: 10°≤α≤90°, or -170°≤α≤-90°, the piezoelectric coefficient of the lithium niobate material piezoelectric layer 3 can include e in the piezoelectric coefficient matrix. 11 Components and e 34Components. It can be understood that the in-plane Euler angle α has a period of 180°. Therefore, the 10° to 90° in one 180° period corresponds to -170° to -90° in another 180° period.

[0075] The acoustic resonator provided in this embodiment uses an anisotropic piezoelectric material for the piezoelectric layer 3, with a preset tangential direction. The angle between the second direction and the positive c-axis in the coordinate system of the preset tangential direction is taken as the in-plane Euler angle α of the piezoelectric material. The c-axis is parallel to the plane of the piezoelectric layer. The range of the Euler angle α is set to a preset range, ensuring that the piezoelectric coefficient of the piezoelectric layer 3 includes the e in the piezoelectric coefficient matrix. 11 Components and e 34 Components, where e 11 The component is used to excite longitudinal modal acoustic waves, e 34 The component is used to excite higher-order shear mode acoustic waves, so that the acoustic waves excited by the piezoelectric layer 3 include at least longitudinal mode acoustic waves and higher-order shear mode acoustic waves. However, the longitudinal mode acoustic waves and higher-order shear mode acoustic waves excited by the piezoelectric layer 3 alone are independent of each other and resonate with each other at different frequencies.

[0076] After the introduction of the coupling adjustment layer 2, since the coupling adjustment layer 2 also participates in mechanical vibration, the equivalent sound velocity (i.e., the phase velocity of sound wave propagation) of the whole composed of the piezoelectric layer 3 and the coupling adjustment layer 2 changes relative to the sound velocity of the single piezoelectric layer 3. That is, the introduction of the coupling adjustment layer 2 can change the sound velocity of the sound wave. Furthermore, since the vibration displacement of the longitudinal modal sound wave and the higher-order shear modal sound wave penetrates to different depths into the piezoelectric layer 3 and the coupling adjustment layer 2, the coupling adjustment layer 2 has different effects on the sound velocity of the two modal sound waves.

[0077] Figure 3 shows a partial cross-sectional structural schematic diagram of another acoustic resonator provided in the embodiment of this application. As shown in Figure 3, the vibration displacement direction of the longitudinal modal acoustic wave is shown by the arrow in Figure 3, mainly along the second direction N perpendicular to the extension direction of the interdigital electrode 4. The vibration displacement direction of the higher-order shear mode acoustic wave is shown by the black dot and cross in the circle in Figure 3, mainly along the extension direction of the interdigital electrode 4, i.e., the first direction M. Furthermore, it can be seen that the longitudinal modal acoustic wave mainly vibrates on the surface of the piezoelectric film, while the higher-order shear mode acoustic wave vibrates throughout the piezoelectric layer 3 and the coupling adjustment layer 2. The vibration displacement of the longitudinal modal acoustic wave and the higher-order shear mode acoustic wave penetrates to different depths into the piezoelectric layer 3 and the coupling adjustment layer 2.

[0078] Since the resonant frequency of a sound wave is determined by the speed of sound (i.e., the phase velocity of sound wave propagation), a coupling adjustment layer 2 made of suitable material and with a suitable thickness ratio to the piezoelectric layer can be set to adjust the resonance of the longitudinal mode sound wave and the higher-order shear mode sound wave to the same frequency, thereby achieving the coupling of these two modes of sound waves. Ultimately, sound waves including two mutually orthogonally polarized coupled modes under a specific propagation direction are excited, realizing the dynamic adjustment of the operating frequency and electromechanical coupling coefficient of the sound wave resonator. This meets the high frequency and large bandwidth requirements of the sound wave resonator in the centimeter wave communication band. Furthermore, the structural design of the sound wave resonator is simple, which can also reduce the complexity and cost of device fabrication.

[0079] As previously known, when the piezoelectric layer 3 is a lithium niobate layer, a preset tangent direction is selected as the X-tangent direction, and the c-axis in the X-tangent coordinate system is selected as the Y-axis. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4 (i.e., the second direction N) and the positive direction of the Y-axis in the X-tangent coordinate system is taken as the Euler angle α. The Euler angle α is selected to satisfy: 10°≤α≤90°, or -170°≤α≤-90°, so that the piezoelectric coefficient of the lithium niobate material piezoelectric layer 3 includes e in the piezoelectric coefficient matrix. 11 Components and e 34 Quantity, so that e 11 The component is used to excite longitudinal modal acoustic waves, e 34 The component is used to excite higher-order shear mode acoustic waves. Based on this, considering that the sound velocity of coupling modulation layer 2 characterizes the phase velocity of the sound wave propagating in coupling modulation layer 2, the sound velocity v of coupling modulation layer 2 is expressed as:

[0080] Where E is the Young's modulus of the material of coupling adjustment layer 2, and ρ is the density of the material of coupling adjustment layer 2; it can be understood that when the material of coupling adjustment layer 2 is determined, the Young's modulus E and density ρ of coupling adjustment layer 2 will be determined, and the sound velocity v of coupling adjustment layer 2 will also be determined.

[0081] Through experiments, the inventors discovered that a coupling adjustment layer 2 made of a suitable material can be set so that the sound velocity v of the coupling adjustment layer 2 satisfies: 1000m / s≤v≤15600m / s, including the endpoint value. This allows the resonance of the longitudinal modal sound wave and the higher-order shear modal sound wave to be adjusted to the same frequency, achieving the coupling of these two modal sound waves, and ultimately exciting a sound wave that includes two mutually orthogonally polarized coupled modes under a specific propagation direction.

[0082] In this application, the coupling adjustment layer 2 may be a silicon dioxide (SiO2) layer, or a (Si) silicon layer, or a polycrystalline silicon (poly-Si) layer, or a silicon nitride (Si3N4) layer, or a sapphire (Al2O3) layer, or a composite layer composed of at least two of the following layers: silicon dioxide layer, silicon layer, polycrystalline silicon layer, silicon nitride layer and sapphire layer.

[0083] Furthermore, considering that the vibration displacements of the longitudinal modal acoustic wave and the higher-order shear modal acoustic wave penetrate to different depths into the piezoelectric layer 3 and the coupling adjustment layer 2, the coupling adjustment layer 2 has different effects on the sound velocity of these two modes. Through experimental research, the inventors discovered, as shown in Figure 1, that when the thickness h of the coupling adjustment layer 2... med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo Satisfying: 3% ≤ h med / h piezo When ≤100%, it is possible to tune the resonance of the longitudinal modal acoustic wave and the higher-order shear modal acoustic wave to the same frequency, so as to achieve the coupling of the two modal acoustic waves and finally excite the acoustic wave including two mutually orthogonally polarized coupled modes under a specific propagation direction.

[0084] The performance of the acoustic resonator provided in the embodiments of this application is described below with examples.

[0085] Example 1:

[0086] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 39°.

[0087] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0088] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 4.5%, wherein, optionally, the thickness h of the coupling adjustment layer 2 is... med =20nm, thickness h of piezoelectric layer 3 piezo =440nm.

[0089] Figure 4 shows the simulated admittance curve of the acoustic resonator in Embodiment 1 operating at 6 GHz. Based on the electromechanical coupling coefficient k of the acoustic resonator... 2 The calculation formula is as follows:

[0090] Among them, f s f is the series resonant frequency of the resonator. p The parallel resonant frequency of the resonator can be read from the simulated admittance curve of the acoustic resonator. Thus, the electromechanical coupling coefficient k of the acoustic resonator in Example 1 can be calculated. 2 The value is 35%, meaning that Example 1 can achieve an operating frequency of 6GHz and an electromechanical coupling coefficient k.2 It is a 35% coupled-mode acoustic resonator.

[0091] Example 2:

[0092] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 39°.

[0093] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0094] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 12.5%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med =50nm, thickness h of piezoelectric layer 3 piezo =400nm.

[0095] Figure 5 shows the simulated admittance curve of the acoustic resonator of Embodiment 2 operating at 6 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 2 can be calculated. 2 The efficiency is 36%, meaning that Example 2 can achieve an operating frequency of 6GHz and an electromechanical coupling coefficient k. 2 It is a 36% coupled-mode acoustic resonator.

[0096] Example 3:

[0097] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 39°.

[0098] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0099] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 12.5%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med = 37.5nm, thickness h of piezoelectric layer 3 piezo =300nm.

[0100] Figure 6 shows the simulated admittance curve of the acoustic resonator of Embodiment 3 operating at 8 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 3 can be calculated.2 The electromechanical coupling coefficient is 37%, meaning that Example 3 can achieve an operating frequency of 8GHz and an electromechanical coupling coefficient k. 2 It is a 37% coupled-mode acoustic resonator.

[0101] Example 4:

[0102] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 39°.

[0103] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0104] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 20%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med =30nm, thickness h of piezoelectric layer 3 piezo =150nm.

[0105] Figure 7 shows the simulated admittance curve of the acoustic resonator of Embodiment 4 operating at 15.5 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 4 can be calculated. 2 The value is 38%, meaning that Example 4 can achieve an operating frequency of 15.5 GHz and an electromechanical coupling coefficient k. 2 It is a 38% coupled-mode acoustic resonator.

[0106] Example 5:

[0107] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 39°.

[0108] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0109] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The percentage is 60%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med =600nm, thickness h of piezoelectric layer 3 piezo =1000nm.

[0110] Figure 8 shows the simulated admittance curve of the acoustic resonator of Embodiment 5 operating at 2 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 5 can be calculated. 2 The electromechanical coupling coefficient is 37%, meaning that Example 5 can achieve an operating frequency of 2GHz and an electromechanical coupling coefficient k. 2 It is a 37% coupled-mode acoustic resonator.

[0111] Example 6:

[0112] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 39°.

[0113] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0114] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 100%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med =400nm, thickness h of piezoelectric layer 3 piezo =400nm.

[0115] Figure 9 shows the simulated admittance curve of the acoustic resonator of Example 6 operating at 4 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Example 6 can be calculated. 2 The electromechanical coupling coefficient is 31%, meaning that Example 6 can achieve an operating frequency of 4GHz and an electromechanical coupling coefficient k. 2 It is a 31% coupled-mode acoustic resonator.

[0116] Example 7:

[0117] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 55°.

[0118] The coupling modulation layer 2 is a silicon dioxide layer, and the sound velocity v of the coupling modulation layer 2 is 5640.8 m / s;

[0119] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 12.5%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med =50nm, thickness h of piezoelectric layer 3 piezo=400nm.

[0120] Figure 10 shows the simulated admittance curve of the acoustic resonator of Embodiment 7 operating at 6 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 7 can be calculated. 2 The value is 28%, meaning that Example 7 can achieve an operating frequency of 6GHz and an electromechanical coupling coefficient k. 2 It is a 28% coupled-mode acoustic resonator.

[0121] Example 8:

[0122] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 40°.

[0123] The coupling adjustment layer 2 is a polycrystalline silicon layer, and the sound velocity v of the coupling adjustment layer 2 is 8304.5 m / s;

[0124] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The value is 26.25%, where, optionally, the thickness h of the coupling adjustment layer 2 is... med =105nm, thickness h of piezoelectric layer 3 piezo =400nm.

[0125] Figure 11 shows the simulated admittance curve of the acoustic resonator of Embodiment 8 operating at 6 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 8 can be calculated. 2 The electromechanical coupling coefficient is 35%, meaning that Example 8 can achieve an operating frequency of 6GHz and an electromechanical coupling coefficient k. 2 It is a 35% coupled-mode acoustic resonator.

[0126] Example 9:

[0127] The piezoelectric layer 3 is a lithium niobate layer with the preset tangent direction being the X tangent direction. The angle between the direction perpendicular to the extension direction of the interdigitated electrode 4, i.e. the second direction N, and the positive Y-axis direction in the coordinate system of the X tangent direction is taken as the Euler angle α, which is 40°.

[0128] The coupling modulation layer 2 is a silicon nitride layer, and the sound velocity v of the coupling modulation layer 2 is 8980.3 m / s;

[0129] The thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo The percentage is 36.25%, where, optionally, the thickness h of the coupling adjustment layer 2 is...med =145nm, thickness h of piezoelectric layer 3 piezo =400nm.

[0130] Figure 12 shows the simulated admittance curve of the acoustic resonator of Embodiment 9 operating at 6 GHz. The electromechanical coupling coefficient k of the acoustic resonator of Embodiment 9 can be calculated. 2 The electromechanical coupling coefficient is 35%, meaning that Example 9 can achieve an operating frequency of 6GHz and an electromechanical coupling coefficient k. 2 It is a 35% coupled-mode acoustic resonator.

[0131] In this application, the thickness of the piezoelectric layer 3 can range from 10 nm to 5000 nm, including the endpoint values.

[0132] The thickness of the coupling adjustment layer 2 can range from 10nm to 5000nm, including the endpoint values.

[0133] It should be noted that, as can be seen from the above simulation admittance curves, there are some stray modes near the parallel resonant frequency point within the band. These stray modes are mostly transverse high-order stray modes, which can be effectively suppressed during device fabrication by using structures such as apodizing electrodes, piston electrodes, or tilting electrodes. This does not hinder the improvement effect of this application on the electromechanical coupling coefficient of the acoustic resonator.

[0134] It should also be noted that once the piezoelectric material, tangent, and Euler angle α of the piezoelectric layer 3 are determined, and the material of the coupling adjustment layer 2 is determined, and when the thickness h of the coupling adjustment layer 2 is determined... med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo When determined, the thickness h of coupling adjustment layer 2 med There are several options, including the thickness h of the piezoelectric layer 3. piezo There are also multiple options, and it is not limited to the thickness values ​​listed in the above embodiments. When the thickness h of the coupling adjustment layer 2 is... med and / or the thickness h of the piezoelectric layer 3 piezo When taking other thickness values, due to the thickness h of coupling adjustment layer 2 med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo It is confirmed that the same acoustic resonator performance can be achieved, so I will not go into details.

[0135] In this application, substrate 1 may be a silicon carbide (SiC) substrate, or a sapphire (Al2O3) substrate, or a gallium nitride (GaN) substrate, or a silicon (Si) substrate.

[0136] In this application, the material of the interdigital electrode 4 may be aluminum, platinum, gold, silver, copper, tungsten, molybdenum, chromium, nickel, titanium-gold alloy, titanium-aluminum alloy, chromium-gold alloy, or chromium-aluminum alloy.

[0137] The number of interdigital electrodes 4 can range from 2 to 1000, meaning the minimum number of interdigital electrodes 4 is 2. Figure 1 illustrates 5 interdigital electrodes 4, and Figure 13 illustrates 2 interdigital electrodes 4. In Figure 13, the width of the coupling adjustment layer 2 or piezoelectric layer 3 along the second direction N is equal to one interdigital electrode periodic wavelength, and the thickness h of the coupling adjustment layer 2 in Figure 13 is... med With the thickness h of piezoelectric layer 3 piezo The ratio h med / h piezo =12.5%.

[0138] The thickness of the interdigital electrode 4 can be 5nm-500nm; the periodic wavelength of the interdigital electrode 4 can be 0.01μm-100μm; the number of interdigital electrode periods of the entire acoustic resonator can be 1 pair-500 pairs; the length of the interdigital electrode 4 along the first direction M can be 1μm-500μm.

[0139] In summary, the acoustic resonator provided in this application includes a substrate and a coupling adjustment layer, a piezoelectric layer, and interdigitated electrodes sequentially disposed on one side of the substrate. The extension direction of the interdigitated electrodes is a first direction, and a second direction is perpendicular to the first direction. Both the first and second directions are parallel to the plane of the piezoelectric layer. The piezoelectric layer is made of anisotropic piezoelectric material, and the tangent of the piezoelectric material is a preset tangent. The angle between the second direction and the positive c-axis in the coordinate system of the preset tangent is taken as the in-plane Euler angle α of the piezoelectric material. The c-axis is parallel to the plane of the piezoelectric layer, and the range of the Euler angle α is set to a preset range, so that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix. 11 Components and e 34 Components, where e 11 The component is used to excite longitudinal modal acoustic waves, e 34The component is used to excite higher-order shear mode acoustic waves, thus the acoustic waves excited by the piezoelectric layer include at least longitudinal mode acoustic waves and higher-order shear mode acoustic waves. Although the longitudinal mode acoustic waves and higher-order shear mode acoustic waves excited by the piezoelectric layer alone are independent of each other and resonate at different frequencies, after the introduction of the coupling modulation layer, since the coupling modulation layer also participates in mechanical vibration, the equivalent sound velocity (i.e., the phase velocity of sound wave propagation) of the whole composed of the piezoelectric layer and the coupling modulation layer changes relative to the sound velocity of a single piezoelectric layer. That is, the introduction of the coupling modulation layer can change the sound velocity of the sound wave. Furthermore, since the vibration displacements of the longitudinal mode acoustic waves and higher-order shear mode acoustic waves penetrate to different depths into the piezoelectric layer and the coupling modulation layer, the coupling modulation layer affects the two modes of the longitudinal mode acoustic waves and higher-order shear mode acoustic waves. The speed of sound affects the frequency of sound waves differently, and the resonant frequency of a sound wave is determined by the speed of sound. Therefore, by setting a suitable material and a coupling adjustment layer with a suitable thickness ratio to the piezoelectric layer, the resonance of the longitudinal mode sound wave and the higher-order shear mode sound wave can be adjusted to the same frequency, achieving the coupling of these two modes of sound waves. Ultimately, sound waves including two mutually orthogonally polarized coupled modes under a specific propagation direction are excited, realizing the dynamic adjustment of the operating frequency and electromechanical coupling coefficient of the sound wave resonator. This meets the high frequency and large bandwidth requirements of the sound wave resonator in the centimeter wave communication band. Furthermore, the structural design of the sound wave resonator is simple, which can also reduce the complexity and cost of device fabrication.

[0140] When the piezoelectric layer is a lithium niobate layer, a preset tangent direction is selected as the X-tangent, and the c-axis in the coordinate system of the X-tangent is the Y-axis. The angle between the second direction and the positive Y-axis in the coordinate system of the X-tangent is taken as the Euler angle α. The Euler angle α is selected to satisfy: 10°≤α≤90°, or -170°≤α≤-90°. This ensures that the piezoelectric coefficient of the lithium niobate material's piezoelectric layer includes the e in the piezoelectric coefficient matrix. 11 Components and e 34 Quantity, so that e 11 The component is used to excite longitudinal modal acoustic waves, e 34 The component is used to excite higher-order shear mode acoustic waves; based on this, a coupling modulation layer of suitable material can be set so that the sound velocity v of the coupling modulation layer satisfies: 1000m / s≤v≤15600m / s, including the endpoint value. Furthermore, considering that the vibration displacements of the longitudinal modal acoustic waves and the higher-order shear mode acoustic waves penetrate to different depths into the piezoelectric layer and the coupling modulation layer, the coupling modulation layer has different effects on the sound velocities of the two modes. When the thickness h of the coupling modulation layer... med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo Satisfying: 3% ≤ h med / h piezoWhen ≤100%, it is possible to tune the resonance of the longitudinal modal acoustic wave and the higher-order shear modal acoustic wave to the same frequency, so as to achieve the coupling of the two modal acoustic waves and finally excite the acoustic wave including two mutually orthogonally polarized coupled modes under a specific propagation direction.

[0141] Ultimately, the acoustic resonator provided in this application embodiment can achieve operating frequencies from 500MHz to over 15GHz, with an electromechanical coupling coefficient (k... 2 A coupled-mode acoustic resonator with a frequency range greater than 6%. This coupled-mode acoustic resonator operates in a frequency range covering commonly used frequency bands such as n78, n79, Wi-Fi 6, and Wi-Fi 7, making it highly suitable for centimeter-wave communication and meeting its stringent requirements for high frequency and wide bandwidth.

[0142] Accordingly, this application also provides a filter, which includes the acoustic resonator provided in any of the above embodiments. Since the acoustic resonator has been described in detail in the foregoing embodiments, it will not be repeated here.

[0143] The various parts of this manual are described in a combination of parallel and progressive methods. Each part focuses on the differences between the other parts, and the same or similar parts can be referred to each other.

[0144] The features described above regarding the disclosed embodiments can be substituted or combined with each other to enable 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 can be implemented in other embodiments without departing from the spirit or 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. An acoustic resonator, characterized in that, include: Substrate; A coupling adjustment layer located on one side of the substrate; A piezoelectric layer located on the side of the coupling adjustment layer away from the substrate, wherein the piezoelectric layer is made of anisotropic piezoelectric material and the tangential direction of the piezoelectric material is a preset tangential direction; The interdigitated electrode is located on the side of the piezoelectric layer away from the substrate. The extension direction of the interdigitated electrode is a first direction, and the second direction is perpendicular to the first direction. Both the first direction and the second direction are parallel to the plane of the piezoelectric layer. The angle between the second direction and the positive c-axis in the coordinate system of the preset tangent is taken as the in-plane Euler angle α of the piezoelectric material, and the c-axis is parallel to the plane where the piezoelectric layer is located. The Euler angle α is within a preset range, such that the piezoelectric coefficient of the piezoelectric layer includes the e in the piezoelectric coefficient matrix. 11 Components and e 34 The components, the piezoelectric coefficient matrix is ​​represented as: Wherein, the e 11 The component is used to excite longitudinal modal acoustic waves, the e 34 The component is used to excite higher-order shear mode acoustic waves.

2. The acoustic resonator according to claim 1, characterized in that, The piezoelectric layer is a lithium niobate layer, or a lithium tantalate layer, or a composite layer composed of at least two of the following: a lithium niobate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, a lithium tantalate layer, and a zinc oxide layer. The thickness of the piezoelectric layer ranges from 10 nm to 5000 nm, including the endpoint values.

3. The acoustic resonator according to claim 1, characterized in that, The coupling adjustment layer is a silicon dioxide layer, or a silicon layer, or a polycrystalline silicon layer, or a silicon nitride layer, or a sapphire layer, or a composite layer composed of at least two of the following: silicon dioxide layer, silicon layer, polycrystalline silicon layer, silicon nitride layer and sapphire layer. The thickness of the coupling adjustment layer ranges from 10nm to 5000nm, including the endpoint values.

4. The acoustic resonator according to claim 1, characterized in that, The piezoelectric layer is a lithium niobate layer, the preset tangent is the X tangent, the c-axis in the coordinate system of the X tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X tangent is taken as the Euler angle α. The Euler angle α satisfies: 10°≤α≤90°, or -170°≤α≤-90°.

5. The acoustic resonator according to claim 4, characterized in that, The sound velocity of the coupling modulation layer characterizes the phase velocity of the sound wave propagating in the coupling modulation layer, and the sound velocity v of the coupling modulation layer is expressed as: Where E is the Young's modulus of the material of the coupling adjustment layer, and ρ is the density of the material of the coupling adjustment layer; The sound velocity v of the coupling adjustment layer satisfies: 1000m / s≤v≤15600m / s, including the endpoint value.

6. The acoustic resonator according to claim 5, characterized in that, The thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo Satisfying: 3% ≤ h med / h piezo ≤100%.

7. The acoustic resonator according to claim 1, characterized in that, The piezoelectric layer is a lithium niobate layer, the preset tangent is the X tangent, the c-axis in the coordinate system of the X tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X tangent is taken as the Euler angle α. The coupling adjustment layer is a silicon dioxide layer, and the sound velocity of the coupling adjustment layer is v = 5640.8 m / s; When the Euler angle α = 39°, the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo = 4.5%, 12.5%, 20%, 60%, or 100%; When the Euler angle α = 55°, the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo =12.5%.

8. The acoustic resonator according to claim 1, characterized in that, The piezoelectric layer is a lithium niobate layer, the preset tangent is the X tangent, the c-axis in the coordinate system of the X tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X tangent is taken as the Euler angle α. The coupling adjustment layer is a polycrystalline silicon layer, and the sound velocity of the coupling adjustment layer is v = 8304.5 m / s; The Euler angle α = 40°, and the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo =26.25%.

9. The acoustic resonator according to claim 1, characterized in that, The piezoelectric layer is a lithium niobate layer, the preset tangent is the X tangent, the c-axis in the coordinate system of the X tangent is the Y-axis, and the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X tangent is taken as the Euler angle α. The coupling adjustment layer is a silicon nitride layer, and the sound velocity of the coupling adjustment layer is v = 8980.3 m / s; The Euler angle α = 40°, and the thickness h of the coupling adjustment layer med With respect to the thickness h of the piezoelectric layer piezo The ratio h med / h piezo =36.25%.

10. A filter, characterized in that, Includes the acoustic resonator according to any one of claims 1-9.

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