Acoustic resonator and filter

Abstract

The invention discloses an acoustic resonator and a filter, and relates to the technical field of radio frequency, the acoustic resonator comprises a substrate, a coupling adjustment layer, a piezoelectric layer and an interdigital electrode, the material of the piezoelectric layer and the tangential direction of the piezoelectric layer are selected, and the value range of an in-plane Euler angle alpha is set; the piezoelectric coefficient of the piezoelectric layer comprises an e11 component and an e34 component in a piezoelectric coefficient matrix, so that the excited sound wave of the piezoelectric layer at least comprises a longitudinal mode sound wave mainly excited by the e11 component and a high-order shear mode sound wave mainly excited by the e34 component; and a coupling adjustment layer which is made of a proper material and has a proper thickness ratio with the piezoelectric layer is arranged, so that the resonance of the longitudinal mode sound wave and the high-order shear mode sound wave is adjusted to the same frequency, coupling is achieved, and finally the sound wave comprising two coupling modes which are mutually orthogonally polarized in a specific propagation direction is excited. The requirements for high frequency and large bandwidth of centimetric wave communication frequency bands are met, the device is simple in structure, and the preparation complexity and cost of the device can be reduced.

Description

Technical Field

[0001] The present application relates to the field of radio frequency technology, and in particular to an acoustic wave resonator and a filter. Background Art

[0002] At present, 5G communication technology is in a stage of rapid development. At the same time, with the urgent market demand for higher data transmission rates, Wi-Fi7 technology has also followed. The various frequency bands used by 5G and Wi-Fi7 not only have higher center frequencies, but also have wider bandwidths. For example, the n77 band of 5G covers a frequency range of 3.3GHz to 4.2GHz, with a bandwidth of 900MHz and a relative bandwidth (FBW) of 24%; the UNII5-8 band of Wi-Fi7 operates in a frequency range of 5.925GHz to 7.125GHz, with a bandwidth of 1200MHz and a relative bandwidth of up to 18.4%. The introduction of these high-frequency broadband bands has significantly improved the performance of the communication system, but at the same time it has also put forward higher technical requirements for the signal processing capabilities of the radio frequency front end (RFFE) to ensure high speed and high reliability of data transmission.

[0003] RF filters are indispensable components in RF front-ends, among which acoustic wave filters have become one of the most popular components due to their small size, high frequency, low insertion loss, and large bandwidth. However, with the continuous increase in operating frequency, acoustic wave filters face more stringent performance challenges. For example, as mentioned above, in the UNII5-8 frequency band (5.925GHz-7.125GHz) of Wi-Fi7, the required relative bandwidth (FBW) has exceeded 18.4%, which requires the electromechanical coupling coefficient (k²) of the acoustic wave resonator to reach at least 36.8%. However, traditional acoustic wave resonators can no longer meet the current demand for high performance. For example, the film bulk acoustic wave resonator (FBAR) has encountered obvious technical limitations in expanding the relative bandwidth; and although the Lamb wave acoustic wave resonator can achieve both higher operating frequency and wider bandwidth, its dependence on the vibration characteristics of the suspended structure leads to problems with the stability of the device structure. In addition, its preparation process is complex and the preparation cost is high. Therefore, improving the performance of acoustic wave resonators working in the centimeter wave band while reducing the complexity and cost of device preparation has become a technical problem that needs to be solved urgently by technicians in this field. Summary of the invention

[0004] In order to solve the above technical problems, the embodiments of the present application provide an acoustic wave resonator and a filter to improve the performance of the acoustic wave resonator operating in the centimeter wave frequency band, while reducing the complexity and cost of device preparation.

[0005] To achieve the above objectives, the present application provides the following technical solutions:

[0006] An acoustic wave resonator, comprising:

[0007] substrate;

[0008] a coupling adjustment layer located on one side of the substrate;

[0009] A piezoelectric layer located on a side of the coupling adjustment layer away from the substrate, wherein the material of the piezoelectric layer is an anisotropic piezoelectric material, and the tangent direction of the piezoelectric material is a preset tangent direction;

[0010] An interdigital electrode located on a side of the piezoelectric layer away from the substrate, wherein the interdigital electrode extends in a first direction, a second direction is perpendicular to the first direction, and both the first direction and the second direction are parallel to the plane where the piezoelectric layer is located;

[0011] The angle between the second direction and the positive direction of the c-axis in the preset tangential coordinate system 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 value range of the Euler angle α is a preset range, so that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Component, the piezoelectric coefficient matrix is ​​expressed as:

[0012]

[0013] Among them, the e 11 The component is used to excite the longitudinal mode acoustic wave, the e 34 The components are 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 consisting of at least two layers of 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 end points.

[0016] Optionally, the coupling adjustment layer is a silicon dioxide layer, or a silicon layer, or a polysilicon layer, or a silicon nitride layer, or a sapphire layer, or a composite layer consisting of at least two layers of a silicon dioxide layer, a silicon layer, a polysilicon layer, a silicon nitride layer and a sapphire layer;

[0017] The coupling adjustment layer has a thickness ranging from 10 nm to 5000 nm, including end points.

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

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

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

[0021]

[0022] Wherein, 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;

[0023] The sound velocity v of the coupling adjustment layer satisfies: 1000m / s≤v≤15600m / s, including the endpoint values.

[0024] Optionally, the thickness h of the coupling adjustment layer med With the thickness of the piezoelectric layer h piezo The ratio h med / h piezo Satisfaction: 3%≤h med / h piezo ≤100%.

[0025] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent direction is an X tangent direction, the c-axis in the coordinate system of the X tangent direction is a Y axis, and the angle formed by the second direction and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α;

[0026] The coupling adjustment layer is a silicon dioxide layer, and the sound velocity v of the coupling adjustment layer is 5640.8 m / s;

[0027] When the Euler angle α=39°, the thickness h of the coupling adjustment layer med With the thickness of the piezoelectric layer h piezo The ratio h med / h piezo =4.5%, 12.5%, 20%, 60% or 100%;

[0028] When the Euler angle α=55°, the thickness h of the coupling adjustment layer med With the thickness of the piezoelectric layer h piezo The ratio h med / h piezo =12.5%.

[0029] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent direction is an X tangent direction, the c-axis in the coordinate system of the X tangent direction is a Y axis, and the angle formed by the second direction and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α;

[0030] The coupling adjustment layer is a polysilicon layer, and the acoustic velocity v of the coupling adjustment layer is 8304.5 m / s;

[0031] The Euler angle α is 40°, and the thickness of the coupling adjustment layer is h med With the thickness of the piezoelectric layer h piezo The ratio h med / h piezo =26.25%.

[0032] Optionally, the piezoelectric layer is a lithium niobate layer, the preset tangent direction is an X tangent direction, the c-axis in the coordinate system of the X tangent direction is a Y axis, and the angle formed by the second direction and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α;

[0033] The coupling adjustment layer is a silicon nitride layer, and the acoustic velocity of the coupling adjustment layer is v=8980.3 m / s;

[0034] The Euler angle α is 40°, and the thickness of the coupling adjustment layer is h med With the thickness of the piezoelectric layer h piezo The ratio h med / h piezo =36.25%.

[0035] A filter comprises the acoustic wave resonator described in any one of the above items.

[0036] Compared with the prior art, the above technical solution has the following advantages:

[0037] The acoustic wave resonator provided in the embodiment of the present application includes a substrate and a coupling adjustment layer, a piezoelectric layer and an interdigital electrode arranged in sequence on one side of the substrate, the extension direction of the interdigital electrode is a first direction, the second direction is perpendicular to the first direction, and the first direction and the second direction are parallel to the plane where the piezoelectric layer is located, by setting the material of the piezoelectric layer to be an anisotropic piezoelectric material, and the tangent direction of the piezoelectric material to be a preset tangent direction, and the angle formed by the second direction and the positive direction of the c-axis in the coordinate system of the preset tangent direction is used as the in-plane Euler angle α of the piezoelectric material, the c-axis is parallel to the plane where the piezoelectric layer is located, 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 Quantity and e 34 Component, where e 11 The component is used to excite the longitudinal mode sound wave, e 34The component is used to excite high-order shear mode sound waves, so that the sound waves excited by the piezoelectric layer include at least longitudinal mode sound waves and high-order shear mode sound waves. Although the longitudinal mode sound waves and high-order shear mode sound waves excited only by the piezoelectric layer are independent of each other and resonate at different frequencies, after the coupling adjustment layer is introduced, since the coupling adjustment layer also participates in the 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 adjustment layer changes relative to the sound velocity of the single piezoelectric layer, that is, the introduction of the coupling adjustment layer can change the sound velocity of the sound wave. Since the vibration displacement of the longitudinal mode sound wave and the high-order shear mode sound wave penetrates into the piezoelectric layer and the coupling adjustment layer at different depths, the coupling adjustment layer has a great influence on the two modes of the longitudinal mode sound wave and the high-order shear mode sound wave. The sound velocity of the state sound wave is affected differently, and the resonant frequency of the sound wave is determined by the sound velocity. Therefore, a coupling adjustment layer with a suitable material and a suitable thickness ratio to the piezoelectric layer can be set to adjust the resonance of the longitudinal mode sound wave and the high-order shear mode sound wave to the same frequency, so as to achieve the coupling of the two modal sound waves, and finally excite sound waves including two mutually orthogonal polarized coupled modes in a specific propagation direction, so as to realize the dynamic adjustment of the operating frequency and electromechanical coupling coefficient of the acoustic wave resonator, and meet the high frequency and large bandwidth requirements of the acoustic wave resonator in the centimeter wave communication band. In addition, the structural design of the acoustic wave resonator is simple, and the complexity and cost of device preparation can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the cross-sectional structure of an acoustic wave resonator provided in an embodiment of the present application;

[0040] Figure 2a A schematic diagram of the in-plane Euler angle α of the piezoelectric material constituting the piezoelectric layer in a coordinate system where the preset tangent direction is the X tangent direction;

[0041] Figure 2b A schematic diagram of the in-plane Euler angle α of the piezoelectric material constituting the piezoelectric layer in a coordinate system where the preset tangent direction is the Y tangent direction;

[0042] Figure 2c A schematic diagram of the in-plane Euler angle α of the piezoelectric material constituting the piezoelectric layer in a coordinate system where the preset tangent direction is the Z tangent direction;

[0043] Figure 3 A schematic diagram of a partial cross-sectional structure of another acoustic wave resonator provided in an embodiment of the present application;

[0044] Figure 4 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 1 of the present application operating at 6 GHz;

[0045] Figure 5 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 2 of the present application operating at 6 GHz;

[0046] Figure 6 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 3 of the present application operating at 8 GHz;

[0047] Figure 7 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 4 of the present application operating at 15.5 GHz;

[0048] Figure 8 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 5 of the present application operating at 2 GHz;

[0049] Fig. 9 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 6 of the present application operating at 4 GHz;

[0050] Fig.10 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 7 of the present application operating at 6 GHz;

[0051] Fig.11 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 8 of the present application operating at 6 GHz;

[0052] Fig.12 This is a simulated admittance curve diagram of the acoustic wave resonator of Example 9 of the present application operating at 6 GHz;

[0053] Fig.13 A schematic diagram of a partial cross-sectional structure of another acoustic wave resonator provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0056] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0057] The embodiment of the present application provides an acoustic wave resonator, Figure 1 FIG. 4 shows a schematic cross-sectional structure diagram of an acoustic wave resonator provided in an embodiment of the present application, such as Figure 1 As shown, the acoustic wave resonator includes a substrate 1, a coupling adjustment layer 2 located on one side of the substrate 1, a piezoelectric layer 3 located on a side of the coupling adjustment layer 2 facing away from the substrate 1, and interdigital electrodes 4 located on a side of the piezoelectric layer 3 facing away from the substrate 1.

[0058] The material of the piezoelectric layer 3 is an anisotropic piezoelectric material, and the tangent direction of the piezoelectric material is a preset tangent direction.

[0059] We know that the tangent direction of a piezoelectric material refers to the direction parallel to the normal of a cutting surface after a piece of piezoelectric material is cut with a cutting surface. The choice of the tangent direction of the piezoelectric material has an important influence on the performance and application of the piezoelectric material. After the tangent direction of the piezoelectric material is determined, the thickness direction of the piezoelectric layer composed of the piezoelectric material is determined, and the coordinate axis along the thickness direction of the piezoelectric layer in the coordinate system of the determined tangent direction is also determined. In the coordinate system of the determined tangent direction, 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 direction can also be determined.

[0060] For example, the preset tangent direction of the piezoelectric material constituting the piezoelectric layer 3 is the X tangent direction. In the coordinate system of the X tangent direction, Figure 1 and Figure 2a As shown, the X axis is parallel to the thickness direction of the piezoelectric layer 3, the Y axis and the Z axis are parallel to the plane where the piezoelectric layer 3 is located, and the X axis, the Y axis and the Z axis are perpendicular to each other.

[0061] For another example, the preset tangent direction of the piezoelectric material constituting the piezoelectric layer 3 is the Y tangent direction. In the Y tangent direction coordinate system, Figure 1 and Figure 2b As shown, the Y axis is parallel to the thickness direction of the piezoelectric layer 3, the X axis and the Z axis are parallel to the plane where the piezoelectric layer 3 is located, and the X axis, the Y axis and the Z axis are perpendicular to each other.

[0062] For another example, the preset tangent direction of the piezoelectric material constituting the piezoelectric layer 3 is the Z tangent direction. In the coordinate system of the Z tangent direction, Figure 1 and Figure 2c As shown, the Z axis is parallel to the thickness direction of the piezoelectric layer 3, the X axis and the Y axis are parallel to the plane where the piezoelectric layer 3 is located, and the X axis, the Y axis and the Z axis are perpendicular to each other.

[0063] In this application, combined Figure 1 , Figure 2a-2c As shown, the extension direction of the interdigital electrode 4 is set to the first direction M, the second direction N is perpendicular to the first direction M, and the first direction M and the second direction N are both parallel to the plane where the piezoelectric layer 3 is located.

[0064] It can be understood that the second direction N is parallel to the horizontal electric field direction formed by the interdigital electrodes 4. As we know, the interdigital electrodes usually form finger-shaped or comb-shaped electrode pairs, which form a periodic pattern on the 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.

[0065] In the present application, the angle formed by the second direction N and the positive direction of the c-axis in the preset tangential coordinate system of the piezoelectric material constituting the piezoelectric layer 3 is taken as the in-plane Euler angle α of the piezoelectric material, wherein 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.

[0066] For example, Figure 2a As shown, the preset tangent direction of the piezoelectric material constituting the piezoelectric layer 3 is the X tangent direction, and the angle formed by the second direction N and the positive direction of the Y axis in the coordinate system of the X tangent direction 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 direction is the Y axis.

[0067] For example, Figure 2b As shown, the preset tangent direction of the piezoelectric material constituting the piezoelectric layer 3 is the Y tangent direction, and the angle formed by the second direction N and the positive direction of the X axis in the coordinate system of the Y tangent direction 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 direction is the X axis.

[0068] Another example, Figure 2c As shown, the preset tangent direction of the piezoelectric material constituting the piezoelectric layer 3 is the Z tangent direction, and the angle formed by the second direction N and the positive direction of the X axis in the coordinate system of the Z tangent direction 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 direction is the X axis.

[0069] A suitable anisotropic piezoelectric material can be selected, and a suitable tangent direction of the piezoelectric material can be selected, so that the value range of the Euler angle α can be selected as a preset range, so that the piezoelectric coefficient of the piezoelectric layer 3 includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Component, where e 11 The component is used to excite the longitudinal mode sound wave, e 34 The components are used to excite higher-order shear mode acoustic waves.

[0070] It can be understood that the piezoelectric coefficient matrix of a piezoelectric material represents the performance of the piezoelectric material in the process of force-electric conversion, which 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 the 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 is represented as a 3×6 matrix:

[0071] (1)

[0072] Among them, the elements in the piezoelectric coefficient matrix are represented by e ij , i represents the direction of the electric field, and j represents the direction of the stress. In the above piezoelectric coefficient matrix, the first three columns are longitudinal piezoelectric coefficients, and the last three columns are shear piezoelectric coefficients. The piezoelectric coefficient matrix is ​​the inherent physical property of the piezoelectric material. The values ​​of the elements in the piezoelectric coefficient matrix depend on the type of piezoelectric material, the tangent direction, and the in-plane Euler angle.

[0073] In the acoustic wave resonator structure proposed in the present application, when the piezoelectric material and the tangent direction 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. When the Euler angle α is determined, the piezoelectric coefficient matrix of the piezoelectric layer 3 is also determined.

[0074] It can also be understood that the excitation of a specific acoustic mode is closely related to the type of piezoelectric material, the tangent direction, and the value range of the in-plane Euler angle α of the piezoelectric layer 3. When the piezoelectric material and its tangent direction of the piezoelectric layer 3 are determined, if the in-plane Euler angle α is different, the type and number of piezoelectric coefficients of the excited acoustic mode are also different. Therefore, by determining the type of piezoelectric material, the tangent direction, and the value range of the in-plane Euler angle α of the piezoelectric layer 3, the piezoelectric coefficients of the acoustic mode excited by the piezoelectric layer 3 can include e in the piezoelectric coefficient matrix. 11 Quantity and e 34 Quantity, e 11 The component is used to excite the longitudinal mode sound wave, e 34 The components are used to excite higher-order shear mode acoustic waves.

[0075] Optionally, the piezoelectric layer 3 may be a lithium niobate layer, a lithium tantalate layer, or a composite layer consisting of at least two layers of a lithium niobate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, a lithium tantalate layer, and a zinc oxide layer. For piezoelectric layers 3 of different piezoelectric materials, a specific tangential direction and a range of values ​​of the in-plane Euler angle α may be selected accordingly, so that the piezoelectric coefficient of the acoustic mode excited by the piezoelectric layer 3 includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Quantity.

[0076] For example, the piezoelectric layer 3 is a lithium niobate layer, and the preset tangent direction is the X tangent direction. As is known above, Figure 2aAs shown, the c-axis in the coordinate system of the X-tangent direction is the Y-axis, that is, the angle formed by the second direction N and the positive direction of the Y-axis in the coordinate system of the X-tangent direction is taken as the Euler angle α. The lithium niobate layer in the X-tangent direction has strong anisotropy. When the in-plane Euler angle α takes different values, the types and quantities of the piezoelectric coefficients of the acoustic mode excited by the piezoelectric layer 3 are also different. When the Euler angle α satisfies: 10°≤α≤90°, or -90°≤α≤-170°, the piezoelectric coefficients of the piezoelectric layer 3 of the lithium niobate material can include e in the piezoelectric coefficient matrix. 11 Quantity and e 34 It can be understood that the in-plane Euler angle α has a period of 180°, so the 10°~90° corresponding to a 180° period corresponds to -90°~-170° in another 180° period.

[0077] The acoustic wave resonator provided in the embodiment of the present application is configured such that the material of the piezoelectric layer 3 is an anisotropic piezoelectric material, and the tangent direction of the piezoelectric material is a preset tangent direction, and the angle formed by the second direction and the positive direction of the c-axis in the coordinate system of the preset tangent direction is used as the in-plane Euler angle α of the piezoelectric material, the c-axis is parallel to the plane where the piezoelectric layer is located, and the value range of the Euler angle α is set to a preset range, so that the piezoelectric coefficient of the piezoelectric layer 3 includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Component, where e 11 The component is used to excite the longitudinal mode sound wave, e 34 The component is used to excite high-order shear mode sound waves, so that the sound waves excited by the piezoelectric layer 3 at least include longitudinal mode sound waves and high-order shear mode sound waves. However, the longitudinal mode sound waves and high-order shear mode sound waves excited only by the piezoelectric layer 3 are independent of each other and resonate at different frequencies.

[0078] After the coupling adjustment layer 2 is introduced, since the coupling adjustment layer 2 also participates in the 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; and since the vibration displacements of the longitudinal modal sound waves and the high-order shear modal sound waves penetrate into the piezoelectric layer 3 and the coupling adjustment layer 2 at different depths, the coupling adjustment layer 2 has different effects on the sound velocities of the two modal sound waves, the longitudinal modal sound waves and the high-order shear modal sound waves.

[0079] Figure 3 FIG. 4 is a schematic diagram showing a partial cross-sectional structure of another acoustic wave resonator provided in an embodiment of the present application. Figure 3 As shown, it can be seen that the vibration displacement direction of the longitudinal mode sound wave is as follows Figure 3 As shown by the middle arrow, the vibration displacement direction of the high-order shear mode acoustic wave is mainly along the second direction N perpendicular to the extension direction of the interdigital electrode 4. Figure 3As shown by the black dots and crosses in the middle circle, it is mainly along the extension direction of the interdigital electrode 4, that is, the first direction M; and it can be seen that the longitudinal modal sound waves mainly vibrate on the surface of the piezoelectric film, and the high-order shear modal sound waves vibrate in the entire piezoelectric layer 3 and the coupling adjustment layer 2, and the vibration displacements of the longitudinal modal sound waves and the high-order shear modal sound waves penetrate into the piezoelectric layer 3 and the coupling adjustment layer 2 at different depths.

[0080] Since the resonant frequency of an acoustic wave is determined by the speed of sound (i.e., the phase velocity of acoustic wave propagation), a coupling adjustment layer 2 made of suitable material and having a suitable thickness ratio to the piezoelectric layer can be provided to adjust the resonance of the longitudinal modal acoustic wave and the high-order shear modal acoustic wave to the same frequency, thereby achieving coupling of the two modal acoustic waves, and ultimately exciting acoustic waves including two mutually orthogonally polarized coupled modes in a specific propagation direction, thereby achieving dynamic adjustment of the operating frequency and electromechanical coupling coefficient of the acoustic wave resonator, and meeting the high frequency and large bandwidth requirements of the acoustic wave resonator in the centimeter wave communication band. In addition, the structural design of the acoustic wave resonator is simple, and the complexity and cost of device preparation can also be reduced.

[0081] As is known from the foregoing, when the piezoelectric layer 3 is a lithium niobate layer, the preset tangent is selected as the X tangent, the c-axis is selected as the Y-axis in the coordinate system of the X tangent, and the angle formed by the direction perpendicular to the extension direction of the interdigital electrode 4, that is, the second direction N and the positive direction of the Y-axis in the coordinate system of the X tangent is taken as the Euler angle α, and the Euler angle α is selected to satisfy: 10°≤α≤90°, or -90°≤α≤-170°, so that the piezoelectric coefficient of the piezoelectric layer 3 of the lithium niobate material includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Quantity, so that e 11 The component is used to excite the longitudinal mode sound wave, e 34 The component is used to excite high-order shear mode sound waves. On this basis, considering that the sound velocity of the coupling adjustment layer 2 represents the phase velocity of the sound wave propagating in the coupling adjustment layer 2, the sound velocity v of the coupling adjustment layer 2 is expressed as:

[0082] (2)

[0083] Among them, E is the Young's modulus of the material of the coupling adjustment layer 2, and ρ is the density of the material of the coupling adjustment layer 2; it can be understood that when the material of the coupling adjustment layer 2 is determined, the Young's modulus E and density ρ of the coupling adjustment layer 2 will be determined, and the sound speed v of the coupling adjustment layer 2 will also be determined.

[0084] The inventors have discovered through experiments that a coupling adjustment layer 2 of suitable material can be provided so that the sound velocity v of the coupling adjustment layer 2 satisfies: 1000m / s≤v≤15600m / s, including the endpoint values, so as to adjust the resonance of the longitudinal modal sound wave and the high-order shear modal sound wave to the same frequency, thereby achieving the coupling of the two modal sound waves, and finally exciting sound waves including two mutually orthogonal polarized coupled modes in a specific propagation direction.

[0085] In the present application, the coupling adjustment layer 2 can 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 consisting of at least two layers of a silicon dioxide layer, a silicon layer, a polycrystalline silicon layer, a silicon nitride layer and a sapphire layer.

[0086] Furthermore, considering that the vibration displacements of the longitudinal mode sound wave and the high-order shear mode sound wave penetrate into the piezoelectric layer 3 and the coupling adjustment layer 2 at different depths, the coupling adjustment layer 2 has different effects on the sound velocities of the longitudinal mode sound wave and the high-order shear mode sound wave. The inventors found through experimental research that, Figure 1 As shown, when the thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo Satisfaction: 3%≤h med / h piezo When ≤100%, the resonance of the longitudinal mode sound wave and the high-order shear mode sound wave can be adjusted to the same frequency, so as to achieve the coupling of the two mode sound waves, and finally stimulate the sound waves including two mutually orthogonal polarization coupling modes in a specific propagation direction.

[0087] The performance of the acoustic wave resonator provided in the embodiments of the present application is described below in detail.

[0088] Embodiment 1:

[0089] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 39°;

[0090] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0091] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 4.5%, wherein, optionally, the thickness h of the coupling adjustment layer 2med = 20nm, the thickness of the piezoelectric layer 3 h piezo =440nm.

[0092] Figure 4 The simulated admittance curve of the acoustic wave resonator of the first embodiment working at 6 GHz is shown. According to the electromechanical coupling coefficient k of the acoustic wave resonator 2 The calculation formula is:

[0093] (3)

[0094] Among them, f s is the series resonant frequency of the resonator, f p is the parallel resonance frequency of the resonator, which can be read from the simulated admittance curve of the acoustic wave resonator. In this way, the electromechanical coupling coefficient k of the acoustic wave resonator of the first embodiment can be calculated. 2 is 35%, that is, the working frequency of the first embodiment can be 6 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic resonator is 35%.

[0095] Embodiment 2:

[0096] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 39°;

[0097] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0098] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 12.5%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =50nm, the thickness of the piezoelectric layer 3 h piezo =400nm.

[0099] Figure 5 The simulated admittance curve of the acoustic wave resonator of the second embodiment working at 6 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the second embodiment can be calculated. 2 is 36%, that is, the working frequency of the second embodiment can be achieved at 6 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic resonator is 36%.

[0100] Embodiment three:

[0101] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 39°;

[0102] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0103] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 12.5%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =37.5nm, the thickness of the piezoelectric layer 3 h piezo =300nm.

[0104] Figure 6 The simulated admittance curve of the acoustic wave resonator of the third embodiment working at 8 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the third embodiment can be calculated. 2 is 37%, that is, the working frequency of the third embodiment can be 8 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic wave resonator is 37%.

[0105] Embodiment 4:

[0106] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 39°;

[0107] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0108] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 20%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =30nm, the thickness of the piezoelectric layer 3 h piezo =150nm.

[0109] Figure 7 The simulated admittance curve of the acoustic wave resonator of the fourth embodiment working at 15.5 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the fourth embodiment can be calculated. 2 is 38%, that is, the fourth embodiment can achieve an operating frequency of 15.5 GHz, and the electromechanical coupling coefficient k 2The coupled mode acoustic wave resonator is 38%.

[0110] Embodiment five:

[0111] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 39°;

[0112] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0113] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 60%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med = 600nm, the thickness of the piezoelectric layer 3 h piezo =1000nm.

[0114] Figure 8 The simulated admittance curve of the acoustic wave resonator of the fifth embodiment working at 2 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the fifth embodiment can be calculated. 2 is 37%, that is, the working frequency of the fifth embodiment can be achieved at 2 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic wave resonator is 37%.

[0115] Embodiment six:

[0116] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 39°;

[0117] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0118] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 100%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =400nm, the thickness of the piezoelectric layer 3 h piezo =400nm.

[0119] Fig. 9The simulated admittance curve of the acoustic wave resonator of the sixth embodiment working at 4 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the sixth embodiment can be calculated. 2 is 31%, that is, the sixth embodiment can achieve an operating frequency of 4 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic wave resonator is 31%.

[0120] Embodiment seven:

[0121] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 55°;

[0122] The coupling adjustment layer 2 is a silicon dioxide layer, and the acoustic velocity v of the coupling adjustment layer 2 is 5640.8 m / s;

[0123] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 12.5%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =50nm, the thickness of the piezoelectric layer 3 h piezo =400nm.

[0124] Fig.10 The simulated admittance curve of the acoustic wave resonator of the seventh embodiment working at 6 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the seventh embodiment can be calculated. 2 is 28%, that is, the seventh embodiment can achieve an operating frequency of 6 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic resonator is 28%.

[0125] Embodiment eight:

[0126] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 40°;

[0127] The coupling adjustment layer 2 is a polysilicon layer, and the acoustic velocity v of the coupling adjustment layer 2 is 8304.5 m / s;

[0128] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 26.25%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =105nm, the thickness of the piezoelectric layer 3 hpiezo =400nm.

[0129] Fig.11 The simulated admittance curve of the acoustic wave resonator of the eighth embodiment working at 6 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the eighth embodiment can be calculated. 2 is 35%, that is, the working frequency of the eighth embodiment can be 6 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic resonator is 35%.

[0130] Embodiment nine:

[0131] The piezoelectric layer 3 is a lithium niobate layer, the preset tangent direction is the X tangent direction, and the angle between the direction perpendicular to the extension direction of the interdigital electrode 4, i.e., the second direction N, and the positive direction of the Y axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is 40°;

[0132] The coupling adjustment layer 2 is a silicon nitride layer, and the acoustic velocity v of the coupling adjustment layer 2 is 8980.3 m / s;

[0133] The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo is 36.25%, wherein, optionally, the thickness h of the coupling adjustment layer 2 med =145nm, the thickness of the piezoelectric layer 3 h piezo =400nm.

[0134] Fig.12 The simulated admittance curve of the acoustic wave resonator of the ninth embodiment working at 6 GHz is shown, and the electromechanical coupling coefficient k of the acoustic wave resonator of the ninth embodiment can be calculated. 2 is 35%, that is, the ninth embodiment can achieve an operating frequency of 6 GHz, and the electromechanical coupling coefficient k 2 The coupled mode acoustic resonator is 35%.

[0135] In the present application, the thickness of the piezoelectric layer 3 may range from 10 nm to 5000 nm, including end points.

[0136] The thickness of the coupling adjustment layer 2 may range from 10 nm to 5000 nm, including end points.

[0137] It should be noted that, from the above-mentioned simulated admittance curves, it can be seen that there are some spurious modes near the parallel resonance frequency point in the band. These spurious modes are mostly lateral high-order spurious modes, which can be effectively suppressed by adopting structures such as apodization electrodes, piston electrodes or inclined electrodes during the device preparation process, and do not hinder the effect of improving the electromechanical coupling coefficient of the acoustic wave resonator in this application.

[0138] It should also be noted that when the piezoelectric material, tangent direction 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 med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo When determining, the thickness h of the coupling adjustment layer 2 med There are many options, the thickness h of the piezoelectric layer 3 piezo There are also many options, 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 other thickness values ​​are taken, due to the thickness h of the coupling adjustment layer 2 med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo It is confirmed that the same acoustic wave resonator performance can be achieved and will not be described in detail.

[0139] In the present application, the 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.

[0140] In the present application, the material of the interdigital electrode 4 can be aluminum, platinum, gold, silver, copper, tungsten, molybdenum, chromium, nickel, titanium-gold alloy, titanium-aluminum alloy, chromium-gold alloy, or chromium-aluminum alloy.

[0141] The number of the interdigital electrodes 4 can be 2 to 1000, that is, the number of the interdigital electrodes 4 is at least 2. Figure 1 Five interdigitated electrodes 4 are shown. Fig.13 Two interdigitated electrodes 4 are shown. Fig.13 In the embodiment, the width of the coupling adjustment layer 2 or the piezoelectric layer 3 along the second direction N is a periodic wavelength of the interdigitated electrodes, and Fig.13 The thickness of the coupling adjustment layer 2 is h med The thickness h of the piezoelectric layer 3 piezo The ratio h med / h piezo =12.5%.

[0142] The thickness of the interdigital electrode 4 can be 5nm-500nm; the interdigital electrode periodic wavelength of the interdigital electrode 4 can be 0.01μm-100μm, and the number of interdigital electrode periods of the entire acoustic wave resonator can be 1 pair-500 pairs; the length of the interdigital electrode 4 along the first direction M can be 1μm-500μm.

[0143] In summary, the acoustic wave resonator provided in the embodiment of the present application includes a substrate and a coupling adjustment layer, a piezoelectric layer and an interdigital electrode arranged in sequence on one side of the substrate, the extension direction of the interdigital electrode is a first direction, the second direction is perpendicular to the first direction, and the first direction and the second direction are parallel to the plane where the piezoelectric layer is located, by setting the material of the piezoelectric layer to an anisotropic piezoelectric material, and the tangent direction of the piezoelectric material to a preset tangent direction, and the angle formed by the second direction and the positive direction of the c-axis in the coordinate system of the preset tangent direction is used as the in-plane Euler angle α of the piezoelectric material, the c-axis is parallel to the plane where the piezoelectric layer is located, 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 Quantity and e 34 Component, where e 11 The component is used to excite the longitudinal mode sound wave, e 34 The component is used to excite high-order shear mode sound waves, so that the sound waves excited by the piezoelectric layer include at least longitudinal mode sound waves and high-order shear mode sound waves. Although the longitudinal mode sound waves and high-order shear mode sound waves excited only by the piezoelectric layer are independent of each other and resonate at different frequencies, after the coupling adjustment layer is introduced, since the coupling adjustment layer also participates in the 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 adjustment layer changes relative to the sound velocity of the single piezoelectric layer, that is, the introduction of the coupling adjustment layer can change the sound velocity of the sound wave. Since the vibration displacement of the longitudinal mode sound wave and the high-order shear mode sound wave penetrates into the piezoelectric layer and the coupling adjustment layer at different depths, the coupling adjustment layer has a great influence on the two modes of the longitudinal mode sound wave and the high-order shear mode sound wave. The sound velocity of the state sound wave is affected differently, and the resonant frequency of the sound wave is determined by the sound velocity. Therefore, a coupling adjustment layer with a suitable material and a suitable thickness ratio to the piezoelectric layer can be set to adjust the resonance of the longitudinal mode sound wave and the high-order shear mode sound wave to the same frequency, so as to achieve the coupling of the two modal sound waves, and finally excite sound waves including two mutually orthogonal polarized coupled modes in a specific propagation direction, so as to realize the dynamic adjustment of the operating frequency and electromechanical coupling coefficient of the acoustic wave resonator, and meet the high frequency and large bandwidth requirements of the acoustic wave resonator in the centimeter wave communication band. In addition, the structural design of the acoustic wave resonator is simple, and the complexity and cost of device preparation can be reduced.

[0144] When the piezoelectric layer is a lithium niobate layer, the preset tangent direction is selected as the X tangent direction, and the c-axis in the coordinate system of the X tangent direction is the Y-axis, that is, the angle between the second direction and the positive direction of the Y-axis in the coordinate system of the X tangent direction is taken as the Euler angle α, and the Euler angle α is selected to satisfy: 10°≤α≤90°, or -90°≤α≤-170°, so that the piezoelectric coefficient of the piezoelectric layer of the lithium niobate material includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Quantity, so that e 11 The component is used to excite the longitudinal mode sound wave, e 34The component is used to excite high-order shear mode sound waves; on this basis, a coupling adjustment layer of suitable material can be set so that the sound velocity v of the coupling adjustment layer satisfies: 1000m / s≤v≤15600m / s, including the end value, and considering that the vibration displacement of the longitudinal mode sound wave and the high-order shear mode sound wave penetrates into the piezoelectric layer and the coupling adjustment layer at different depths, so that the coupling adjustment layer has different effects on the sound velocity of the two modal sound waves, the thickness of the coupling adjustment layer h med The thickness of the piezoelectric layer h piezo The ratio h med / h piezo Satisfaction: 3%≤h med / h piezo When ≤100%, the resonance of the longitudinal mode sound wave and the high-order shear mode sound wave can be adjusted to the same frequency, so as to achieve the coupling of the two mode sound waves, and finally stimulate the sound waves including two mutually orthogonal polarization coupling modes in a specific propagation direction.

[0145] Finally, the acoustic wave resonator provided in the embodiment of the present application can achieve an operating frequency ranging from 500 MHz to above 15 GHz, and the electromechanical coupling coefficient (k 2 ) is greater than 6%. The operating frequency range of this coupled mode acoustic wave resonator covers common frequency bands such as n78, n79, Wi-Fi6, and Wi-Fi7. It is very suitable for the field of centimeter wave communications and meets its strict requirements for high frequency and wide bandwidth.

[0146] Accordingly, an embodiment of the present application further provides a filter, which includes the acoustic wave resonator provided by any of the above embodiments. Since the acoustic wave resonator has been described in detail in the above embodiments, it will not be repeated here.

[0147] The various parts in this manual are described in a combination of parallel and progressive ways. Each part focuses on the differences from other parts, and the same or similar parts between the various parts can be referenced to each other.

[0148] With respect to the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other, so that professionals in the field can implement or use the present application. Various modifications to these embodiments will be apparent to professionals in the field, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An acoustic wave resonator, characterized in that: include: substrate; a coupling adjustment layer located on one side of the substrate; A piezoelectric layer located on a side of the coupling adjustment layer away from the substrate, wherein the material of the piezoelectric layer is an anisotropic piezoelectric material, and the tangent direction of the piezoelectric material is a preset tangent direction; An interdigital electrode located on a side of the piezoelectric layer away from the substrate, wherein the interdigital electrode extends in a first direction, a second direction is perpendicular to the first direction, and both the first direction and the second direction are parallel to the plane where the piezoelectric layer is located; The angle between the second direction and the positive direction of the c-axis in the preset tangential coordinate system 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 value range of the Euler angle α is a preset range, so that the piezoelectric coefficient of the piezoelectric layer includes e in the piezoelectric coefficient matrix 11 Quantity and e 34 Component, the piezoelectric coefficient matrix is ​​expressed as: Among them, the e 11 The component is used to excite the longitudinal mode acoustic wave, the e 34 The components are used to excite higher-order shear mode acoustic waves.

2. The acoustic wave 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 consisting of at least two layers of 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 end points.

3. The acoustic wave resonator according to claim 1, characterized in that The coupling adjustment layer is a silicon dioxide layer, or a silicon layer, or a polysilicon layer, or a silicon nitride layer, or a sapphire layer, or a composite layer consisting of at least two layers of the silicon dioxide layer, the silicon layer, the polysilicon layer, the silicon nitride layer and the sapphire layer; The coupling adjustment layer has a thickness ranging from 10 nm to 5000 nm, including end points.

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

5. The acoustic wave resonator according to claim 4, characterized in that The acoustic velocity of the coupling adjustment layer represents the phase velocity of the acoustic wave propagating in the coupling adjustment layer. The acoustic velocity v of the coupling adjustment layer is expressed as: Wherein, 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 values.

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

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

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

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

10. A filter, characterized in that: The acoustic wave resonator comprises the acoustic wave resonator according to any one of claims 1 to 9.

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