Acoustic wave resonator and electronic device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- UNIV OF SCI & TECH OF CHINA
- Filing Date
- 2025-03-25
- Publication Date
- 2026-06-11
AI Technical Summary
When existing acoustic resonators enhance waveguide effects, higher-order acoustic modes cause stray acoustic modes to appear near the resonant frequency of the main acoustic mode, affecting the signal quality of the communication system.
By designing the thickness of the piezoelectric layer and the ratio of the periodic wavelengths of the interdigitated electrodes, the dispersion characteristics of the longitudinal main acoustic mode and the shear stray acoustic mode are modulated to make their resonant frequencies similar, and the stray acoustic mode is integrated into the main acoustic mode.
It effectively suppresses stray acoustic modes, improves the efficiency of the conversion between electrical and mechanical energy of the main acoustic mode, and enhances the signal processing capability of the communication system.
Smart Images
Figure CN2025084670_11062026_PF_FP_ABST
Abstract
Description
An acoustic resonator and electronic device
[0001] This application claims priority to Chinese Patent Application No. 202411785843.7, filed on December 3, 2024, entitled "An Acoustic Resonator and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of acoustic resonator technology, and more specifically, to an acoustic resonator and electronic device. Background Technology
[0003] Among various radio frequency filters, acoustic filters have long been a key component in communication systems due to their advantages such as small size, low cost, and high stability. Acoustic filters are typically constructed from acoustic resonators; therefore, the demand for high-performance acoustic filters is essentially a demand for high-performance acoustic resonators. While existing acoustic resonators achieve good waveguide effects, they also enhance higher-order acoustic modes, which may lead to the appearance of stray acoustic modes near the resonant frequency of the dominant acoustic mode. Summary of the Invention
[0004] In view of this, this application provides an acoustic resonator and electronic device that effectively solves the technical problems existing in the prior art. It adjusts the longitudinal main acoustic mode and the shear stray acoustic mode to similar resonant frequencies, which not only effectively suppresses the stray acoustic mode, but also integrates it into the main acoustic mode, thereby improving the efficiency of the conversion between electrical energy and mechanical energy in the main acoustic mode.
[0005] To achieve the above objectives, the technical solution provided in this application is as follows:
[0006] An acoustic resonator, comprising:
[0007] Substrate;
[0008] A piezoelectric layer disposed on one side surface of the substrate;
[0009] The interdigitated electrode is disposed on the surface of the piezoelectric layer opposite to the substrate. The interdigitated electrode includes a first finger electrode and a second finger electrode arranged alternately at intervals. The length extension directions of the first finger electrode and the second finger electrode are the same.
[0010] The tangential direction of the piezoelectric material in the piezoelectric layer is a set tangential direction, the in-plane Euler angle of the piezoelectric layer is a set angle, and the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode is a set ratio, so that the difference in resonant frequency of the two acoustic modes under the action of at least two different piezoelectric coefficients is within the allowable range. The at least two different piezoelectric coefficients include at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, and the two acoustic modes include a longitudinal main acoustic mode and a shear stray acoustic mode.
[0011] Optionally, the piezoelectric material of the piezoelectric layer is lithium niobate, the set tangent is the X-tangent, and the in-plane Euler angle is the angle between the direction perpendicular to the length extension direction and the +Y axis direction in the coordinate system of the X-tangent.
[0012] Optionally, the in-plane Euler angle range of the piezoelectric layer is greater than or equal to 10° and less than or equal to 80° or greater than or equal to -170° and less than or equal to -100°.
[0013] Optionally, the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode is greater than or equal to 0.1 and less than or equal to 0.9.
[0014] Optionally, the longitudinal dominant acoustic mode is a zero-order longitudinal acoustic mode, and the shear stray acoustic mode is a higher-order shear acoustic mode.
[0015] Optionally, the substrate is any one of silicon carbide substrate, sapphire substrate, gallium nitride substrate, silicon substrate and composite substrate;
[0016] The composite substrate is formed by stacking at least two sub-substrate layers, and the material of at least one of the sub-substrate layers is different from that of the other sub-substrate layers. The material of the sub-substrate layer is any one of silicon carbide, sapphire, polycrystalline silicon, silicon, and silicon dioxide.
[0017] Optionally, the piezoelectric layer is any one of lithium niobate layer, lithium tantalate layer and composite piezoelectric layer;
[0018] The composite piezoelectric layer is formed by stacking at least two sub-piezoelectric layers. The material of at least one of the sub-piezoelectric layers is different from that of the other sub-piezoelectric layers. The sub-piezoelectric layer is any one of lithium niobate layer, aluminum nitride layer, scandium-doped aluminum nitride layer, lithium tantalate layer and zinc oxide layer. The thickness of the piezoelectric layer is greater than or equal to 10 nm and less than or equal to 5000 nm.
[0019] Optionally, the material of either the first finger electrode or the second finger electrode is any one of aluminum, copper, platinum, gold, silver, tungsten, molybdenum, chromium, nickel, titanium-gold alloy, titanium-aluminum alloy, chromium-gold alloy, and chromium-aluminum alloy.
[0020] Optionally, the number of any one of the first finger electrodes and the second finger electrode is greater than or equal to 2 and less than or equal to 500.
[0021] The thickness of the finger electrode is greater than or equal to 5 nm and less than or equal to 500 nm;
[0022] The width of the finger electrode is greater than or equal to 0.001 μm and less than or equal to 5 μm;
[0023] The length of the finger electrode is greater than or equal to 1 μm and less than or equal to 500 μm.
[0024] Based on the same inventive concept, this application also provides an electronic device, which includes the aforementioned acoustic resonator.
[0025] Compared with existing technologies, the technical solution provided in this application has at least the following advantages:
[0026] This application provides an acoustic resonator and an electronic device. The acoustic resonator includes: a substrate; a piezoelectric layer disposed on one side surface of the substrate; interdigitated electrodes disposed on the side surface of the piezoelectric layer opposite to the substrate, the interdigitated electrodes including alternating first and second interdigitated electrodes, the first and second interdigitated electrodes having the same length extension direction; the tangential direction of the piezoelectric material of the piezoelectric layer is a set tangential direction, the in-plane Euler angle of the piezoelectric layer is a set angle, and the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrodes is a set ratio, such that the difference in resonant frequency between two acoustic modes with at least two different piezoelectric coefficients is within an allowable range, wherein the at least two different piezoelectric coefficients include at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, and the two acoustic modes include a longitudinal dominant acoustic mode and a shear stray acoustic mode.
[0027] As described above, in the acoustic resonator provided by this application, both the longitudinal dominant acoustic mode and the shear stray acoustic mode are dispersive waves. Therefore, by designing the ratio of the piezoelectric layer thickness to the periodic wavelength of the interdigitated electrodes, the dispersion characteristics of the longitudinal dominant acoustic mode and the shear stray acoustic mode can be controlled, causing their dispersion curves to intersect. This achieves the goal of adjusting the longitudinal dominant acoustic mode and the shear stray acoustic mode to similar resonant frequencies, effectively suppressing the stray acoustic mode and integrating it into the dominant acoustic mode, thus improving the efficiency of the conversion between electrical and mechanical energy in the dominant acoustic mode. The technical solution provided by this application breaks through the existing method of suppressing shear stray acoustic modes by thinning the piezoelectric layer, achieving the goals of suppressing stray acoustic modes and improving the electromechanical coupling coefficient, providing a new approach to the suppression of stray acoustic modes in the field of resonators. Attached Figure Description
[0028] 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0029] Figure 1 is a schematic diagram of the structure of an acoustic resonator provided in an embodiment of this application;
[0030] Figure 2 is a three-dimensional schematic diagram of an X-tangential internal Euler angle rotation provided in an embodiment of this application;
[0031] Figure 3 is a schematic diagram of another acoustic resonator provided in an embodiment of this application;
[0032] Figure 4 is a schematic diagram of polarization displacement provided in an embodiment of this application;
[0033] Figure 5 is a schematic diagram of another polarization displacement provided in an embodiment of this application;
[0034] Figure 6 is a simulation admittance curve provided in an embodiment of this application;
[0035] Figure 7 is another simulation admittance curve provided in an embodiment of this application;
[0036] Figure 8 is another simulation admittance curve provided in an embodiment of this application;
[0037] Figure 9 is another simulation admittance curve provided in the embodiment of this application;
[0038] Figure 10 is another simulation admittance curve provided in the embodiment of this application;
[0039] Figure 11 is another simulation admittance curve provided in the embodiment of this application. Detailed Implementation
[0040] 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.
[0041] As described in the background section, Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra Reliable Low Latency Communications (uRLLC) are the three major application scenarios of 5G. Among them, enhanced mobile broadband is one of the important application scenarios of 5G, aiming to meet users' growing demand for high-speed data, such as ultra-high-definition video, virtual reality (VR), and augmented reality (AR). However, these place high demands on the radio frequency (RF) signal processing capabilities of smart devices. On the one hand, the physical bandwidth of new frequency bands in 5G New Radio (NR) has been significantly improved; on the other hand, carrier aggregation (CA) technology still plays an important role in making full use of the spectrum. Therefore, radio frequency filters need to have greater bandwidth, lower insertion loss, and excellent out-of-band (OoB) rejection performance to improve signal sensitivity and eliminate out-of-band response, thereby avoiding mutual interference with other CA communication channels.
[0042] Among various radio frequency filters, acoustic wave filters have long been a key component in communication systems due to their advantages such as small size, low cost, and high stability. Acoustic wave filters are typically constructed from acoustic resonators; therefore, the demand for high-performance acoustic wave filters is essentially a demand for high-performance acoustic resonators. In recent years, emerging piezoelectric on-insulator (POI) heterosubstrate technologies have proven highly suitable for broadband acoustic wave resonator applications, especially surface acoustic wave (SAW) resonators, achieving significant progress in manufacturing low-loss, high-bandwidth, high-performance SAW resonators. Typically, POI heterosubstrate consists of a piezoelectric thin film and a high-speed substrate (such as Si, sapphire, SiC, etc.). Some POI heterosubstrate also have a SiO2 interlayer between the piezoelectric thin film and the high-speed substrate. This multilayer structure achieves better waveguide effects, solving the problem of acoustic energy leakage to the substrate in traditional SAW devices and significantly improving the electromechanical coupling coefficient (k2) of the main acoustic wave mode.
[0043] However, the waveguide effect is a double-edged sword, as it simultaneously enhances higher-order acoustic modes, which can lead to the emergence of stray acoustic modes near the resonant frequency of the dominant acoustic mode. In modern radio communication standards, these stray acoustic modes are generally undesirable because strict out-of-band channel attenuation levels are specified in the front-end circuitry to suppress interactions and signal distortion between associated CA bands. Therefore, maintaining a high k² value for the dominant acoustic mode while suppressing stray acoustic modes on the POI heterostructure is a pressing problem to be solved.
[0044] Based on this, the present application provides an acoustic resonator and electronic device, which effectively solves the technical problems existing in the prior art. By adjusting the longitudinal main acoustic mode and the shear stray acoustic mode to similar resonant frequencies, it not only achieves effective suppression of stray acoustic modes, but also integrates them into the main acoustic mode, thereby improving the efficiency of the conversion between electrical energy and mechanical energy in the main acoustic mode.
[0045] To achieve the above objectives, the technical solutions provided by the embodiments of this application are as follows, and the technical solutions provided by the embodiments of this application will be described in detail with reference to Figures 1 to 11.
[0046] Referring to Figures 1 and 2, Figure 1 is a structural schematic diagram of an acoustic resonator provided in an embodiment of this application, and Figure 2 is a three-dimensional schematic diagram of an acoustic resonator with internal Euler angle rotation in the X-tangential direction provided in an embodiment of this application. The acoustic resonator provided in this embodiment of the application includes: a substrate 1; a piezoelectric layer 2 disposed on one side surface of the substrate 1; and interdigitated electrodes 3 disposed on the side surface of the piezoelectric layer 2 opposite to the substrate 1. The interdigitated electrodes 3 include alternating first finger electrodes 31 and second finger electrodes 32, and the length extension direction Z1 of the first finger electrodes 31 and the second finger electrodes 32 is the same.
[0047] The tangential direction of the piezoelectric material in the piezoelectric layer 2 is a predetermined tangential direction, and the in-plane Euler angle of the piezoelectric layer 2 is a predetermined angle. The piezoelectric layer 2 can be any one of lithium niobate layer, lithium tantalate layer, and composite piezoelectric layer; the composite piezoelectric layer is formed by stacking at least two sub-piezoelectric layers, and the material of at least one of the sub-piezoelectric layers is different from the material of the other sub-piezoelectric layers. The sub-piezoelectric layer can be any one of lithium niobate layer, aluminum nitride layer, scandium-doped aluminum nitride layer, lithium tantalate layer, and zinc oxide layer.
[0048] In some embodiments, the piezoelectric material of the piezoelectric layer 2 is lithium niobate, the defined tangential direction is the X-tangential direction, and the in-plane Euler angle is the angle between the direction perpendicular to the length extension direction (the length extension direction is the length extension direction of the first finger electrode 31 or the second finger electrode 32 mentioned above) Z1 and the +Y axis direction in the coordinate system of the X-tangential direction. The in-plane Euler angle of the piezoelectric layer 2 is greater than or equal to 10° and less than or equal to 80° or greater than or equal to -170° and less than or equal to -100°.
[0049] Specifically, the X-tangential lithium niobate provided in this application has abundant piezoelectric coefficients and significant anisotropy advantages. On the one hand, the abundant and large piezoelectric coefficients make the acoustic resonator based on lithium niobate layer 2 superior to existing thin-film bulk acoustic resonators based on aluminum nitride piezoelectric materials in terms of the important performance of electromechanical coupling coefficient. On the other hand, in order to solve the problem of low operating frequency of traditional zero-order shear mode surface acoustic resonators, it is necessary to select longitudinal acoustic modes with higher acoustic wave propagation speed to improve the operating frequency. The relationship between acoustic wave propagation speed and operating frequency can be expressed as: f = v / λ, where f is the operating frequency, v is the acoustic wave propagation speed, and λ is the periodic wavelength of the interdigitated electrode. Because X-tangential lithium niobate has abundant piezoelectric coefficients and significant anisotropy, by adjusting the in-plane Euler angle, the piezoelectric coefficient acting on the longitudinal acoustic mode can be made to reach a high level. When the in-plane Euler angle rotates within the range of greater than or equal to 10° and less than or equal to 80° or greater than or equal to -170° and less than or equal to -100°, the longitudinal acoustic mode can be effectively excited.
[0050] Understandably, in-plane Euler angles have a period of 180°, and the entire plane is 360°. Therefore, 10° to 80° corresponds to -170° to -100° in another 180° period. That is, the in-plane Euler angle α1 can be the angle between the direction Y1, which is perpendicular to the length extension direction Z1 of the finger electrode, and the +Y axis direction in the X-tangential coordinate system. In this case, the angle range of the in-plane Euler angle α1 of the piezoelectric layer 2 is greater than or equal to 10° and less than or equal to 80°. Alternatively, the in-plane Euler angle α2 provided in this embodiment is the angle between the direction -Y1, which is perpendicular to the length extension direction Z1 of the finger electrode, and the +Y axis direction in the X-tangential coordinate system. In this case, the angle range of the in-plane Euler angle α2 of the piezoelectric layer 2 is greater than or equal to -170° and less than or equal to -100°.
[0051] Referring to Figure 3, which is a schematic diagram of another acoustic resonator provided in this embodiment, specifically a two-dimensional cross-sectional view of an acoustic resonator in which the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigital electrode 3 is 0.5. In the acoustic resonator provided in this embodiment, the ratio of the thickness of the piezoelectric layer 2 to the periodic wavelength of the interdigital electrode 3 is a set ratio, so that the difference in resonant frequencies of the two acoustic modes with at least two different piezoelectric coefficients is within an allowable range. The at least two different piezoelectric coefficients include at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, and the two acoustic modes include one longitudinal dominant acoustic mode and one shear stray acoustic mode.
[0052] Understandably, in the acoustic resonator provided in this application, both the longitudinal dominant acoustic mode and the shear stray acoustic mode are dispersive waves. Therefore, by designing the ratio of the thickness of the piezoelectric layer 2 to the periodic wavelength of the interdigitated electrode 3, the dispersion characteristics of the longitudinal dominant acoustic mode and the shear stray acoustic mode are controlled, so that the dispersion curves of the longitudinal dominant acoustic mode and the shear stray acoustic mode intersect. This achieves the purpose of adjusting the longitudinal dominant acoustic mode and the shear stray acoustic mode to similar resonant frequencies, not only effectively suppressing the stray acoustic mode but also integrating it into the dominant acoustic mode, thus improving the efficiency of the conversion between electrical and mechanical energy in the dominant acoustic mode. The technical solution provided in this application breaks through the existing method of suppressing the shear stray acoustic mode by thinning the piezoelectric layer, achieving the purpose of suppressing stray acoustic modes and improving the electromechanical coupling coefficient, providing a new approach to the suppression of stray acoustic modes in the field of resonators.
[0053] Optionally, when the piezoelectric material of the piezoelectric layer 2 is lithium niobate, and the set tangential direction is X-tangential, as described above, when the in-plane Euler angle rotates within the range of greater than or equal to 10° and less than or equal to 80°, or within the range of greater than or equal to -170° and less than or equal to -100°, the longitudinal acoustic mode can be effectively excited. However, the abundant piezoelectric coefficient of X-tangential lithium niobate means that not only the longitudinal piezoelectric coefficient but also the shear piezoelectric coefficient is affected at this time. The presence of these shear piezoelectric coefficients excites some stray acoustic modes, among which the operating frequency of the higher-order shear stray acoustic modes is closest to the longitudinal main acoustic mode. Since both the longitudinal main acoustic mode and the higher-order shear stray acoustic mode are dispersive waves in the acoustic resonator structure proposed in this invention, their dispersion characteristics can be controlled by adjusting the influence of the substrate on these two acoustic modes. This modulation can be achieved by designing the ratio of the piezoelectric layer thickness h to the periodic wavelength λ of the interdigitated electrode. Since the mode shapes of the two acoustic modes differ, the substrate's influence on them also varies. When the ratio of the piezoelectric layer thickness h to the periodic wavelength λ of the interdigitated electrode varies within the range of ≥0.1 and ≤0.9, the dispersion curves of the two acoustic modes intersect, meaning that the two acoustic modes have similar resonant frequencies. This not only effectively suppresses stray acoustic modes but also integrates them into the dominant acoustic mode, improving the efficiency of the interconversion between electrical and mechanical energy in the dominant acoustic mode. In this case, the longitudinal dominant acoustic mode provided in this embodiment is a zero-order longitudinal acoustic mode, and the shear stray acoustic mode is a higher-order shear acoustic mode.
[0054] Referring to Figures 4 and 5, Figure 4 is a schematic diagram of polarization displacement provided by an embodiment of this application. Specifically, it is a two-dimensional cross-sectional polarization displacement diagram of an acoustic resonator under the action of the longitudinal dominant acoustic mode when the piezoelectric material of the piezoelectric layer 2 is lithium niobate, the set tangent is the X-tangent, and the ratio of the thickness h of the lithium niobate layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.5. Figure 5 is a schematic diagram of polarization displacement provided by an embodiment of this application. Specifically, it is a two-dimensional cross-sectional polarization displacement diagram of an acoustic resonator under the action of the shear stray acoustic mode when the piezoelectric material of the piezoelectric layer 2 is lithium niobate, the set tangent is the X-tangent, and the ratio of the thickness h of the lithium niobate layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.5. It can be seen that the polarization displacement direction of the longitudinal dominant acoustic mode is the direction of the horizontal electric field, and the polarization displacement direction of the shear stray acoustic mode is the length extension direction of the interdigitated electrode 3. The polarization displacement directions of both acoustic modes are located in the YZ plane and are perpendicular to each other. When the dispersion curves of two acoustic modes intersect, that is, when the two acoustic modes have similar resonant frequencies, the acoustic resonator simultaneously has two polarization shifts at the resonant frequency point, as shown in Figures 4 and 5.
[0055] Optionally, the substrate 1 provided in this application embodiment can be any one of silicon carbide (SiC) substrate, sapphire (Al2O3) substrate, gallium nitride (GaN) substrate, silicon (Si) substrate, and composite substrate; the composite substrate is formed by stacking at least two sub-substrate layers, and the material of at least one of the sub-substrate layers is different from the material of the other sub-substrate layers. The material of the sub-substrate layer is any one of silicon carbide, sapphire, polycrystalline silicon (poly-Si), silicon, and silicon dioxide (SiO2).
[0056] Furthermore, the thickness of the piezoelectric layer 2 provided in this application embodiment can be greater than or equal to 10 nm and less than or equal to 5000 nm.
[0057] Furthermore, the material of any one of the first finger electrode 31 and the second finger electrode 32 provided in this application embodiment is any one of aluminum, copper, platinum, gold, silver, tungsten, molybdenum, chromium, nickel, titanium-gold alloy, titanium-aluminum alloy, chromium-gold alloy, and chromium-aluminum alloy. The number of any one of the first finger electrodes 31 and the second finger electrode 32 is greater than or equal to 2 and less than or equal to 500; the thickness of the finger electrode is greater than or equal to 5 nm and less than or equal to 500 nm; the width of the finger electrode is greater than or equal to 0.001 μm and less than or equal to 5 μm; and the length of the finger electrode is greater than or equal to 1 μm and less than or equal to 500 μm.
[0058] As described above, the technical solution provided in this application controls the dispersion characteristics of two acoustic modes with at least two different piezoelectric coefficients by designing the piezoelectric material of the piezoelectric layer 2 to a set tangent and by optimizing the in-plane Euler angle of the piezoelectric layer 2 and the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3. The two acoustic modes are then adjusted to similar resonant frequencies. The at least two different piezoelectric coefficients include at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, and the two acoustic modes include one longitudinal main acoustic mode and one shear stray acoustic mode.
[0059] When the piezoelectric material of the piezoelectric layer 2 is lithium niobate, and the set tangent is the X-tangent, the in-plane Euler angle is the angle between the direction perpendicular to the length extension direction Z1 and the +Y axis direction in the coordinate system of the X-tangent. When the in-plane Euler angle of the lithium niobate layer 2 rotates within the range of greater than or equal to 10° and less than or equal to 80° or greater than or equal to -170° and less than or equal to -100°, and the ratio of the thickness of the lithium niobate layer 2 to the periodic wavelength of the interdigitated electrode 3 is greater than or equal to 0.1 and less than or equal to 0.9, the dispersion curves of the longitudinal dominant acoustic mode and the shear stray acoustic mode can intersect, thereby achieving the purpose of adjusting the longitudinal dominant acoustic mode and the shear stray acoustic mode to similar resonant frequencies. This not only effectively suppresses the stray acoustic mode but also integrates it into the dominant acoustic mode, improving the efficiency of the conversion between electrical energy and mechanical energy in the dominant acoustic mode.
[0060] The following description, using lithium niobate with piezoelectric layer 2 in the X-direction as an example, combines several simulated admittance curves to provide a more detailed description of the acoustic resonator provided in this application embodiment. Referring to Figure 6, a simulated admittance curve is provided in this application embodiment. Specifically, it shows the simulated admittance curve of an acoustic resonator operating at 9.5 GHz, where the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.48 and the in-plane Euler angle is 40°, exhibiting the combined effect of longitudinal main acoustic wave mode and sheared stray acoustic wave mode with similar resonant frequencies. Calculations show its electromechanical coupling coefficient to be 33%. Electromechanical coupling coefficient k... 2 The calculation formula is:
[0061] Among them, f s f is the series resonant frequency of the acoustic resonator. p This is the parallel resonant frequency of the acoustic resonator.
[0062] Figure 7 shows another simulated admittance curve provided by an embodiment of this application. Specifically, it is the simulated admittance curve of an acoustic resonator operating at 4.1 GHz, where the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.15 and the in-plane Euler angle is 40°. The longitudinal main acoustic wave mode and the shear stray acoustic wave mode with similar resonant frequencies are combined. The electromechanical coupling coefficient can be calculated to be 14.5%.
[0063] Figure 8 shows another simulated admittance curve provided by an embodiment of this application. Specifically, it is the simulated admittance curve of an acoustic resonator operating at 16.3 GHz when the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.75 and the in-plane Euler angle is 40°. The longitudinal main acoustic wave mode and the shear stray acoustic wave mode with similar resonant frequencies are combined. The electromechanical coupling coefficient can be calculated to be 18%.
[0064] Figure 9 shows another simulated admittance curve provided in an embodiment of this application. Specifically, it is the simulated admittance curve of an acoustic resonator operating at 9.5 GHz, where the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.48 and the in-plane Euler angle is 55°. The longitudinal main acoustic wave mode and the shear stray acoustic wave mode with similar resonant frequencies are combined. The electromechanical coupling coefficient can be calculated to be 26.3%.
[0065] Figure 10 shows another simulated admittance curve provided in an embodiment of this application. Specifically, it is the simulated admittance curve of an acoustic resonator operating at 2.8 GHz, where the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.48 and the in-plane Euler angle is 40°. The longitudinal main acoustic wave mode and the shear stray acoustic wave mode with similar resonant frequencies are combined. The electromechanical coupling coefficient can be calculated to be 32.9%.
[0066] Figure 11 shows another simulated admittance curve provided in this application embodiment. Specifically, it is the simulated admittance curve of an acoustic resonator operating at 19.7 GHz when the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is 0.5 and the in-plane Euler angle is 40°, with the longitudinal main acoustic wave mode and the shear stray acoustic wave mode having similar resonant frequencies. The electromechanical coupling coefficient can be calculated to be 32.8%.
[0067] Based on the same inventive concept, this application also provides an electronic device, which includes the acoustic resonator provided in any of the above embodiments.
[0068] In summary, this application provides an acoustic resonator and an electronic device. The acoustic resonator includes: a substrate; a piezoelectric layer disposed on one side surface of the substrate; and interdigitated electrodes disposed on the piezoelectric layer on the side surface opposite to the substrate. The interdigitated electrodes include alternating first and second interdigitated electrodes, with the first and second interdigitated electrodes having the same length extension direction. The tangential direction of the piezoelectric material in the piezoelectric layer is a predetermined tangential direction, the in-plane Euler angle of the piezoelectric layer is a predetermined angle, and the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrodes is a predetermined ratio, such that the difference in resonant frequencies of two acoustic modes with at least two different piezoelectric coefficients is within an allowable range. The at least two different piezoelectric coefficients include at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, and the two acoustic modes include a longitudinal dominant acoustic mode and a shear stray acoustic mode.
[0069] When the piezoelectric material of the piezoelectric layer 2 is lithium niobate, and the set tangent is the X-tangent, the in-plane Euler angle is the angle between the direction perpendicular to the length extension direction Z1 and the +Y axis direction in the coordinate system of the X-tangent. When the in-plane Euler angle is set to rotate within the range of greater than or equal to 10° and less than or equal to 80° or greater than or equal to -170° and less than or equal to -100°, the longitudinal dominant acoustic mode can be effectively excited. Since both the longitudinal dominant acoustic mode and the shear stray acoustic mode are dispersive waves, the ratio of the thickness h of the piezoelectric layer 2 to the periodic wavelength λ of the interdigitated electrode 3 is set to vary within the range of greater than or equal to 0.1 and less than or equal to 0.9, so that the dispersion curves of the longitudinal dominant acoustic mode and the shear stray acoustic mode intersect, thereby achieving the purpose of adjusting the longitudinal dominant acoustic mode and the shear stray acoustic mode to similar resonant frequencies. Ultimately, the operating frequency of the acoustic resonator can be varied from 2 GHz to over 20 GHz, and the electromechanical coupling coefficient (k2) remains above 6%.
[0070] As described above, in the acoustic resonator provided in this application, both the longitudinal dominant acoustic mode and the shear stray acoustic mode are dispersive waves. Therefore, by designing the ratio of the piezoelectric layer thickness to the periodic wavelength of the interdigitated electrodes, the dispersion characteristics of the longitudinal dominant acoustic mode and the shear stray acoustic mode are controlled, causing their dispersion curves to intersect. This achieves the goal of adjusting the longitudinal dominant acoustic mode and the shear stray acoustic mode to similar resonant frequencies, effectively suppressing the stray acoustic mode and integrating it into the dominant acoustic mode, thus improving the efficiency of energy conversion between electrical and mechanical energy in the dominant acoustic mode. The technical solution provided in this application breaks through the existing method of suppressing shear stray acoustic modes by thinning the piezoelectric layer, achieving the goals of suppressing stray acoustic modes and improving the electromechanical coupling coefficient, providing a new approach to suppressing stray acoustic modes in the field of resonators. The acoustic resonator provided in this application is highly suitable for carrier aggregation technology in 5G wireless communication, effectively avoiding mutual interference between different carrier aggregation channels. Furthermore, the acoustic resonator provided in this application operates over multiple centimeter-wave communication bands and features high operating frequency, wide bandwidth, and excellent out-of-band rejection performance, making it ideal for applications in the field of centimeter-wave communication.
[0071] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and other terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0073] In the embodiments of this application, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0074] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0075] In the embodiments of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0076] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.
Claims
1. An acoustic wave resonator, characterized by, Acoustic resonators include: Substrate; A piezoelectric layer disposed on one side surface of the substrate; The interdigitated electrode is disposed on the surface of the piezoelectric layer opposite to the substrate. The interdigitated electrode includes a first finger electrode and a second finger electrode arranged alternately at intervals. The length extension directions of the first finger electrode and the second finger electrode are the same. The tangential direction of the piezoelectric material in the piezoelectric layer is a set tangential direction, the in-plane Euler angle of the piezoelectric layer is a set angle, and the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode is a set ratio, so that the difference in resonant frequency of the two acoustic modes under the action of at least two different piezoelectric coefficients is within the allowable range. The at least two different piezoelectric coefficients include at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, and the two acoustic modes include a longitudinal main acoustic mode and a shear stray acoustic mode. Wherein, the piezoelectric material of the piezoelectric layer is lithium niobate, the set tangent is the X tangent, and the in-plane Euler angle is the angle between the direction perpendicular to the length extension direction and the +Y axis direction in the coordinate system of the X tangent; The in-plane Euler angle range of the piezoelectric layer is greater than or equal to 10° and less than or equal to 80° or greater than or equal to -170° and less than or equal to -100°. The ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode is greater than or equal to 0.1 and less than or equal to 0.
9. By adjusting the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigitated electrode, the dispersion characteristics of the longitudinal dominant acoustic mode and the shear stray acoustic mode can be controlled, so that the dispersion curves of the longitudinal dominant acoustic mode and the shear stray acoustic mode intersect, thereby achieving the purpose of adjusting the longitudinal dominant acoustic mode and the shear stray acoustic mode to similar resonant frequencies. The longitudinal main acoustic mode is a zero-order longitudinal acoustic mode, and the shear stray acoustic mode is a higher-order shear acoustic mode.
2. The acoustic resonator of claim 1, wherein, The substrate is any one of silicon carbide substrate, sapphire substrate, gallium nitride substrate, silicon substrate and composite substrate; The composite substrate is formed by stacking at least two sub-substrate layers, and the material of at least one of the sub-substrate layers is different from that of the other sub-substrate layers. The material of the sub-substrate layer is any one of silicon carbide, sapphire, polycrystalline silicon, silicon, and silicon dioxide.
3. The acoustic resonator of claim 1, wherein, The piezoelectric layer is any one of lithium niobate layer, lithium tantalate layer and composite piezoelectric layer; The composite piezoelectric layer is formed by stacking at least two sub-piezoelectric layers. The material of at least one of the sub-piezoelectric layers is different from that of the other sub-piezoelectric layers. The sub-piezoelectric layer is any one of lithium niobate layer, aluminum nitride layer, scandium-doped aluminum nitride layer, lithium tantalate layer and zinc oxide layer. The thickness of the piezoelectric layer is greater than or equal to 10 nm and less than or equal to 5000 nm.
4. The acoustic resonator of claim 1, wherein, The material of either the first finger electrode or the second finger electrode is any one of aluminum, copper, platinum, gold, silver, tungsten, molybdenum, chromium, nickel, titanium-gold alloy, titanium-aluminum alloy, chromium-gold alloy, and chromium-aluminum alloy.
5. The acoustic wave resonator of claim 1, wherein, The number of any one of the first and second finger electrodes is greater than or equal to 2 and less than or equal to 500. The thickness of the finger electrode is greater than or equal to 5 nm and less than or equal to 500 nm; The width of the finger electrode is greater than or equal to 0.001 μm and less than or equal to 5 μm; The length of the finger electrode is greater than or equal to 1 μm and less than or equal to 500 μm.
6. An electronic device, comprising: The electronic device includes the acoustic resonator according to any one of claims 1 to 5.