A longitudinal leakage surface acoustic wave resonator and filter

Abstract

This application relates to the field of heterogeneous integrated device fabrication technology, and provides a longitudinal leakage surface acoustic wave resonator and filter. The longitudinal leakage surface acoustic wave resonator includes a supporting substrate, a piezoelectric thin film disposed on the supporting substrate, and an electrode array disposed on the piezoelectric thin film. The supporting substrate can be a rotary-cut silicon carbide substrate, and the piezoelectric thin film can be made of lithium niobate or lithium tantalate. By using a resonator combining a rotary-cut silicon carbide supporting substrate and a piezoelectric thin film, the loss near the anti-resonance frequency can be reduced without changing the sound velocity of the substrate material, resulting in a wider ultra-low loss region for the resonator, thereby achieving superior resonator and filter performance.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous integrated device fabrication technology, and in particular to a longitudinal leakage surface acoustic wave resonator and filter. Background Technology

[0002] Since the operating frequency of a surface acoustic wave (SAW) device equals the acoustic mode velocity divided by the interdigitated electrode period, a higher acoustic mode velocity will increase the device's operating frequency for the same interdigitated electrode period. Currently, commonly used SAW devices typically employ horizontal shear wave (SH-SAW) and longitudinal leakage SAW (LL-SAW). The velocity of sound in SH-SAW is approximately 4000 m / s, while that in LL-SAW is approximately 6400 m / s. Therefore, LL-SAW can significantly increase the operating frequency of resonators and filters, making it suitable for 5G communication frequency bands.

[0003] To achieve a high Q value (2π times the ratio of stored energy to consumed energy per cycle) in a low-loss LL-SAW resonator, from a materials science perspective, a piezoelectric thin film and a supporting substrate structure with a bulk wave velocity greater than the longitudinal leakage surface acoustic wave (LL-SAW) velocity of 6400 m / s are required. This would raise the resonator's cutoff frequency above the anti-resonance frequency, effectively preventing bulk wave radiation from the LL-SAW to the supporting substrate and confining the energy within the piezoelectric thin film on the upper surface. Existing solutions propose using high-velocity substrates to improve the energy confinement effect of the LL-SAW and reduce losses near the anti-resonance frequency, but these are costly and cannot be mass-produced. Therefore, a resonator structure that can reduce losses near the anti-resonance frequency is urgently needed. Summary of the Invention

[0004] To address the problem that existing resonators cannot reduce losses near the anti-resonance frequency, embodiments of this application provide a longitudinal leakage surface acoustic wave resonator, comprising:

[0005] Support substrate; the support substrate is a rotary-cut silicon carbide substrate;

[0006] A piezoelectric thin film disposed on a supporting substrate; the material of the piezoelectric thin film is lithium niobate or lithium tantalate.

[0007] An electrode array disposed on a piezoelectric thin film.

[0008] Furthermore, the Euler angles of the cut surfaces and in-plane directions of the supporting substrate are (90°, 90°, 0°~50°); or;

[0009] The Euler angles of the cut surface and in-plane direction of the supporting substrate are (0°, 70°~110°, 0°).

[0010] Furthermore, the electrode array includes an interdigitated electrode array and a reflective gate electrode array;

[0011] The center-to-center spacing of the reflective grid electrodes in the reflective grid electrode array is less than or equal to the center-to-center spacing of the interdigital electrodes in the interdigital electrode array.

[0012] Furthermore, the thickness of the interdigitated electrodes in the interdigitated electrode array is within the range of [60nm, 160nm].

[0013] Furthermore, the crystal Euler angles of the piezoelectric thin film are (0°, 0°, θ°), (90°, 90°, θ°), (0°, 90°, θ°), or (0°, θ°, 0°), where θ represents the angle.

[0014] Furthermore, the reflective gate electrode array includes a first reflective gate electrode subarray and a second reflective gate electrode subarray;

[0015] The first reflective grating electrode subarray is disposed at one end of the interdigital electrode array, and the second reflective grating electrode subarray is disposed at the other end of the interdigital electrode array;

[0016] The center-to-center spacing of the reflective grid electrodes in the first reflective grid electrode subarray is not equal to the center-to-center spacing of the reflective grid electrodes in the second reflective grid electrode subarray;

[0017] The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray is less than or equal to the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array, and the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray is less than or equal to the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array.

[0018] Furthermore, the interdigitated electrode array and the reflective grid electrode array have an angle of inclination relative to the normal direction of the electrode array;

[0019] The tilt angle is within the preset tilt angle range, which is [-10°, 10°].

[0020] Furthermore, the resonator also includes:

[0021] A dielectric layer disposed on a supporting substrate;

[0022] The dielectric layer is made of silicon oxide, silicon nitride, aluminum nitride, or aluminum oxide.

[0023] The ratio of the thickness of the dielectric layer to the thickness of the piezoelectric film is less than a preset threshold; the preset threshold is 1.2.

[0024] Furthermore, the thickness of the piezoelectric film is within the range of [200 nm, 800 nm].

[0025] Accordingly, this application provides a filter including multiple resonators, wherein the resonators are the aforementioned longitudinal leakage surface acoustic wave resonators;

[0026] Multiple resonators are cascaded, bridged, or coupled based on a pre-defined topology; or;

[0027] Multiple resonators are cascaded or bridged with external capacitors and inductors.

[0028] The embodiments of this application have the following beneficial effects:

[0029] This application provides a longitudinal leakage surface acoustic wave resonator and filter. The longitudinal leakage surface acoustic wave resonator includes a supporting substrate, a piezoelectric thin film disposed on the supporting substrate, and an electrode array disposed on the piezoelectric thin film. The supporting substrate can be a rotary-cut silicon carbide substrate, and the piezoelectric thin film can be made of lithium niobate or lithium tantalate. By using a resonator combining a rotary-cut silicon carbide supporting substrate and a piezoelectric thin film, the loss near the anti-resonance frequency can be reduced without changing the sound velocity of the substrate material. This results in a wider ultra-low loss region for the resonator, thereby achieving superior resonator and filter performance. Attached Figure Description

[0030] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic cross-sectional view of a longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application;

[0032] Figure 2 This is a top view schematic diagram of a longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application;

[0033] Figure 3 This is a cross-sectional schematic diagram of a support substrate provided in an embodiment of this application;

[0034] Figure 4 This is an electrical response curve of an LL-SAW resonator based on a lithium niobate bulk single crystal, provided in an embodiment of this application.

[0035] Figure 5 This is an electrical response curve of an LL-SAW resonator based on a lithium niobate thin film / sapphire piezoelectric heterostructure provided in an embodiment of this application;

[0036] Figure 6This is an electrical response curve of an LL-SAW resonator based on a lithium niobate thin film / silicon carbide piezoelectric heterostructure provided in an embodiment of this application;

[0037] Figure 7 This is the conductivity response curve of a longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application;

[0038] Figure 8 This is a schematic cross-sectional view of another longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application;

[0039] Figure 9 This is a schematic diagram of another filter structure provided in an embodiment of this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely one embodiment of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0041] The term "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. In the description of the embodiments of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. Furthermore, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data used can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. In addition, the terms "comprising," "having," and "being," and any variations thereof, are intended to cover non-exclusive inclusion.

[0042] The following describes a specific embodiment of a longitudinal leakage surface acoustic wave resonator according to this application. Figure 1 This is a schematic cross-sectional view of a longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application. Figure 2 This is a top view schematic diagram of a longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application. Figure 3This is a cross-sectional schematic diagram of a support substrate provided in an embodiment of this application. This specification provides the structural composition shown in the embodiments or accompanying drawings, but based on conventional or non-inventive labor, more or fewer modules or components may be included. The structural composition listed in the embodiments is merely one of many possible compositions and does not represent the only possible composition. In actual implementation, the structural composition shown in the embodiments or accompanying drawings can be followed.

[0043] Specifically, such as Figure 1 , Figure 2 and Figure 3 As shown, the longitudinal leakage surface acoustic wave resonator may include a supporting substrate, a piezoelectric thin film disposed on the supporting substrate, and an electrode array disposed on the piezoelectric thin film. The supporting substrate may be a rotary-cut silicon carbide (SiC) substrate, and the piezoelectric thin film may be made of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

[0044] In this embodiment, the Euler angles of the cut surface and in-plane direction of the supporting substrate can be (90°, 90°, 0°~50°), or (0°, 70°~110°, 0°). Specifically, the Euler angles of the cut surface and in-plane direction of the supporting substrate can be (90°, 90°, 0°), or (90°, 90°, 24°).

[0045] The cutoff frequency of a resonator is the inflection point where the conductivity curve increases significantly. Below this frequency, the conductivity is low, and the acoustic energy leakage of the resonator is low, mainly confined to the resonator surface, resulting in good resonance. Above this frequency, the conductivity is high, and a large amount of surface acoustic waves will radiate downwards into the supporting substrate, leading to energy loss. Therefore, the cutoff frequency directly depends on the velocity of sound in the supporting substrate material. Figure 4 This is an electrical response curve of an LL-SAW resonator based on a lithium niobate bulk single crystal, provided in an embodiment of this application. Figure 5 This is the electrical response curve of an LL-SAW resonator based on a lithium niobate thin film / sapphire piezoelectric heterostructure provided in an embodiment of this application. Figure 6This figure shows the electrical response curve of an LL-SAW resonator based on a lithium niobate thin film / silicon carbide piezoelectric heterostructure, as provided in this application embodiment. The cut surface and the Euler angle in the in-plane direction of the silicon carbide piezoelectric heterostructure can be (0°, 0°, 0°). In each resonator, the thickness of the interdigitated electrodes can be 100 nm, the electrode period can be 1.7 μm, and the piezoelectric thin film can be X-cut lithium niobate. The thickness of the lithium niobate thin film in both the LL-SAW resonator based on a lithium niobate thin film / sapphire piezoelectric heterostructure and the LL-SAW resonator based on a lithium niobate thin film / silicon carbide piezoelectric heterostructure can be 420 nm. In the figure, the upper curve is the admittance curve, and the lower curve is the conductance curve. Conductance is the real part of admittance. The difference between the vertical coordinates of the admittance and conductance curves directly reflects the amount of energy radiated by the surface acoustic wave towards the supporting substrate at that frequency. The more energy radiated downwards, the greater the conductance of the resonator, and the greater the corresponding loss and the lower the Q value. When the supporting substrate is a single crystal of lithium niobate (LiNbO3), the bulk wave velocity is 3700 m / s, and the cutoff frequency of the resonator is 2.3 GHz. When the supporting substrate is sapphire, the bulk wave velocity is 6000 m / s, and the cutoff frequency is 3.4 GHz. When the supporting substrate is silicon carbide (SiC), the bulk wave velocity is 7100 m / s, and the cutoff frequency is 4.5 GHz. It is evident that single piezoelectric crystals or traditional silicon-based, sapphire-based, and quartz-based piezoelectric thin film materials are insufficient to effectively confine LL-SAW energy, mainly because the sound velocities of the supporting substrates such as piezoelectric single crystals, silicon, sapphire, and quartz are not high enough, causing the cutoff frequency of the LL-SAW resonator to be lower than the device's operating frequency. However, the slow shear wave velocity of the silicon carbide (SiC) substrate is as high as 7100 m / s. Therefore, silicon carbide (SiC)-based piezoelectric thin film heterostructures can be used to realize high-performance LL-SAW resonators and filters.

[0046] However, for the first two, since the cutoff frequency is lower than the operating frequency of LL-SAW, it is evident that the difference between the admittance and conductance curves of the LL-SAW mode response is small, and the resonator admittance ratio (the difference between the ordinates of the resonant point and the anti-resonant point) is small. For the latter, the difference between the admittance and conductance curves is large near the resonant frequency, indicating low loss, while a rise in the conductance curve appears near the anti-resonant frequency, i.e., the high-loss region. This loss zoning phenomenon causes significant fluctuations in the Q value of the LL-SAW resonator within the operating frequency range and introduces spurious wave modes, which is detrimental to the subsequent implementation of high-performance acoustic filters.

[0047] Figure 7 This is the conductance response curve of a longitudinal leakage surface acoustic wave resonator provided in an embodiment of this application, such as... Figure 7As shown, when the cut surface and in-plane Euler angle of the supporting substrate were adjusted from (0°, 0°, 0°) to (90°, 90°, 0°) and (90°, 90°, 24°), the resonant frequency and anti-resonant frequency of the LL-SAW resonator did not change significantly, indicating that adjusting the cut of the supporting substrate did not have a significant impact on the sound velocity of the substrate material. Furthermore, from Figure 7 It can be seen that the conductivity curve of the LL-SAW resonator increases slightly before the resonant frequency, remains almost unchanged after the resonant frequency, and decreases significantly around the anti-resonant frequency, indicating a substantial reduction in device loss before and after the anti-resonant frequency. Therefore, the silicon carbide support substrate with Euler angles of (90°, 90°, 24°) in both the cut and in-plane directions achieves further reduced conductivity in the 4.2–4.5 GHz range compared to the silicon carbide support substrate with Euler angles of (90°, 90°, 0°) in both the cut and in-plane directions. Thus, by employing a resonator combining a rotary-cut silicon carbide support substrate with a piezoelectric thin film, losses near the anti-resonant frequency can be reduced without altering the sound velocity of the substrate material, resulting in a wider ultra-low loss region for the resonator and ultimately achieving superior resonator and filter performance.

[0048] In this embodiment, the electrode array may include an interdigital electrode array and a reflective gate electrode array. The interdigital electrode array and the reflective gate electrode array may be arranged in parallel on the piezoelectric film. The reflective gate electrodes may be short-circuited or open-circuited. This embodiment does not impose specific limitations. The center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array may be equal to the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. The center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array may be less than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. By reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array, the reflection frequency range of the reflective gate electrode array can be increased, thereby suppressing stray modes of longitudinal leakage waves and improving the performance of the resonator.

[0049] In some possible implementations, the reflective gate electrode array may include a first reflective gate electrode subarray and a second reflective gate electrode subarray. The first reflective gate electrode subarray may be disposed at one end of the interdigital electrode array, and the second reflective gate electrode subarray may be disposed at the other end of the interdigital electrode array. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may be equal to the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may be less than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array, and the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray may also be less than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. By reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array, the reflection frequency range of the reflective gate electrode array can be increased, thereby suppressing spurious modes of longitudinal leakage waves and improving the performance of the resonator.

[0050] In some possible implementations, the reflective gate electrode array may include a first reflective gate electrode subarray and a second reflective gate electrode subarray. The first reflective gate electrode subarray may be disposed at one end of the interdigital electrode array, and the second reflective gate electrode subarray may be disposed at the other end of the interdigital electrode array. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may not be equal to the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may be smaller than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array, and the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray may also be smaller than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. By reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array, the reflection frequency range of the reflective gate electrode array can be increased, thereby suppressing spurious modes of longitudinal leakage waves and improving the performance of the resonator.

[0051] In some possible implementations, the reflective gate electrode array may include a first reflective gate electrode subarray, a second reflective gate electrode subarray, a third reflective gate electrode subarray, and a fourth reflective gate electrode subarray. The first and third reflective gate electrode subarrays may be disposed at one end of the interdigitated electrode array, and the second and fourth reflective gate electrode subarrays may be disposed at the other end of the interdigitated electrode array. The center-to-center spacing of the reflective gate electrodes in the first, second, third, and fourth reflective gate electrode subarrays may be equal, partially equal, or completely unequal. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray can be smaller than the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray can be smaller than the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; and the center-to-center spacing of the reflective gate electrodes in the third reflective gate electrode subarray can be smaller than the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; and the center-to-center spacing of the reflective gate electrode array can be smaller than the center-to-center spacing of the interdigitated electrodes in the fourth reflective gate electrode subarray. By setting multiple reflective gate arrays and reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode arrays, the reflection frequency range of the reflective gate electrode arrays can be further improved, thereby further suppressing the spurious modes of longitudinal leakage waves and improving the performance of the resonator.

[0052] In this embodiment, the interdigital electrode array and the reflective gate electrode array are tilted at an angle θ relative to the normal direction of the electrode array. This tilt angle can be within a preset tilt angle range. Optionally, the preset tilt angle range can be [-10°, 10°]. By placing the interdigital electrode array and the reflective gate electrode array at an angle on the piezoelectric film, the Q value can be improved and clutter can be suppressed.

[0053] In this embodiment, the thickness of the interdigitated electrodes in the interdigitated electrode array can be within the range of [60nm, 160nm]. By controlling the thickness of the interdigitated electrodes, the increased acoustic scattering of LL-SAW caused by excessive electrode thickness can be prevented, which can further reduce device loss.

[0054] In this embodiment, the lengths of the interdigitated electrodes in the interdigitated electrode array can be different. The interdigitated electrode array can include extremely short interdigitated electrodes (or pseudo-interdigitated electrodes) located in the same length direction as each interdigitated electrode, which can improve the Q value.

[0055] In this embodiment, the crystal Euler angle of the piezoelectric thin film can be any one of (0°, 0°, θ°), (90°, 90°, θ°), (0°, 90°, θ°), and (0°, θ°, 0°), where θ represents the angle, and the thickness of the piezoelectric thin film can be in the range [200nm, 800nm].

[0056] The longitudinal leakage surface acoustic wave resonator provided in this application, by employing a resonator combining a rotary-cut silicon carbide support substrate and a piezoelectric thin film, can reduce losses near the anti-resonance frequency without changing the sound velocity of the substrate material. This results in a wider ultra-low loss region for the resonator, leading to superior resonator and filter performance. Reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array can increase the reflection frequency range of the array, thereby suppressing spurious modes of the longitudinal leakage wave and improving resonator performance. Tilting the interdigital electrode array and the reflective gate electrode array on the piezoelectric thin film can improve the Q value and suppress spurious signals. Controlling the thickness of the interdigital electrodes can prevent increased acoustic scattering in the LL-SAW due to excessive electrode thickness, further reducing device losses.

[0057] The following describes a specific embodiment of a longitudinal leakage surface acoustic wave resonator according to this application. Figure 8 This is a schematic cross-sectional view of another longitudinally leaking surface acoustic wave resonator provided in an embodiment of this application. This specification provides the structural composition shown in the embodiments or figures, but based on conventional or non-inventive labor, more or fewer modules or components may be included. The structural composition listed in the embodiments is merely one of many possible combinations and does not represent the only structural composition. In actual implementation, the structural composition shown in the embodiments or figures can be followed.

[0058] Specifically, such as Figure 8 As shown, the structure of a longitudinal leakage surface acoustic wave resonator may include a substrate, a dielectric layer disposed on the substrate, a piezoelectric thin film disposed on the dielectric layer, and an electrode array disposed on the piezoelectric thin film. The supporting substrate may be a rotary-cut silicon carbide (SiC) substrate, and the piezoelectric thin film may be made of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3).

[0059] In this embodiment, the Euler angles of the cut surface and in-plane direction of the supporting substrate can be (90°, 90°, 0°~50°), or (0°, 70°~110°, 0°). Specifically, the Euler angles of the cut surface and in-plane direction of the supporting substrate can be (90°, 90°, 0°), or (90°, 90°, 24°).

[0060] In this embodiment, the electrode array may include an interdigital electrode array and a reflective gate electrode array. The interdigital electrode array and the reflective gate electrode array may be arranged in parallel on the piezoelectric film. The reflective gate electrodes may be short-circuited or open-circuited. This embodiment does not impose specific limitations. The center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array may be equal to the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. The center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array may be less than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. By reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array, the reflection frequency range of the reflective gate electrode array can be increased, thereby suppressing stray modes of longitudinal leakage waves and improving the performance of the resonator.

[0061] In some possible implementations, the reflective gate electrode array may include a first reflective gate electrode subarray and a second reflective gate electrode subarray. The first reflective gate electrode subarray may be disposed at one end of the interdigital electrode array, and the second reflective gate electrode subarray may be disposed at the other end of the interdigital electrode array. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may be equal to the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may be less than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array, and the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray may also be less than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. By reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array, the reflection frequency range of the reflective gate electrode array can be increased, thereby suppressing spurious modes of longitudinal leakage waves and improving the performance of the resonator.

[0062] In some possible implementations, the reflective gate electrode array may include a first reflective gate electrode subarray and a second reflective gate electrode subarray. The first reflective gate electrode subarray may be disposed at one end of the interdigital electrode array, and the second reflective gate electrode subarray may be disposed at the other end of the interdigital electrode array. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may not be equal to the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray may be smaller than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array, and the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray may also be smaller than the center-to-center spacing of the interdigital electrodes in the interdigital electrode array. By reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array, the reflection frequency range of the reflective gate electrode array can be increased, thereby suppressing spurious modes of longitudinal leakage waves and improving the performance of the resonator.

[0063] In some possible implementations, the reflective gate electrode array may include a first reflective gate electrode subarray, a second reflective gate electrode subarray, a third reflective gate electrode subarray, and a fourth reflective gate electrode subarray. The first and third reflective gate electrode subarrays may be disposed at one end of the interdigitated electrode array, and the second and fourth reflective gate electrode subarrays may be disposed at the other end of the interdigitated electrode array. The center-to-center spacing of the reflective gate electrodes in the first, second, third, and fourth reflective gate electrode subarrays may be equal, partially equal, or completely unequal. The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray can be smaller than the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray can be smaller than the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; and the center-to-center spacing of the reflective gate electrodes in the third reflective gate electrode subarray can be smaller than the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; and the center-to-center spacing of the reflective gate electrode array can be smaller than the center-to-center spacing of the interdigitated electrodes in the fourth reflective gate electrode subarray. By setting multiple reflective gate arrays and reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode arrays, the reflection frequency range of the reflective gate electrode arrays can be further improved, thereby further suppressing the spurious modes of longitudinal leakage waves and improving the performance of the resonator.

[0064] In this embodiment, the interdigital electrode array and the reflective gate electrode array are tilted at an angle θ relative to the normal direction of the electrode array. This tilt angle can be within a preset tilt angle range. Optionally, the preset tilt angle range can be [-10°, 10°]. By placing the interdigital electrode array and the reflective gate electrode array at an angle on the piezoelectric film, the Q value can be improved and clutter can be suppressed.

[0065] In this embodiment, the thickness of the interdigitated electrodes in the interdigitated electrode array can be within the range of [60nm, 160nm]. By controlling the thickness of the interdigitated electrodes, the increased acoustic scattering of LL-SAW caused by excessive electrode thickness can be prevented, which can further reduce device loss.

[0066] In this embodiment, the lengths of the interdigitated electrodes in the interdigitated electrode array can be different. The interdigitated electrode array can include extremely short interdigitated electrodes (or pseudo-interdigitated electrodes) located in the same length direction as each interdigitated electrode, which can improve the Q value.

[0067] In some possible implementations, the structure of a longitudinally leaking surface acoustic wave resonator may include a substrate, a piezoelectric thin film disposed on the substrate, an electrode array disposed on the piezoelectric thin film, and a dielectric layer disposed on the electrode array. Alternatively, the structure of a longitudinally leaking surface acoustic wave resonator may include a substrate, a first dielectric layer disposed on the substrate, a piezoelectric thin film disposed on the first dielectric layer, an electrode array disposed on the piezoelectric thin film, and a second dielectric layer disposed on the electrode array.

[0068] In this embodiment, the dielectric layer can be made of silicon dioxide (SiO2). x Non-metallic materials such as silicon nitride (Si3N4), aluminum nitride (AlN), or aluminum oxide (Al2O3) can be used to assist in material preparation processes, which can further improve the Q value of resonators or compensate for the temperature stability of devices.

[0069] In this embodiment, the Euler angle of the piezoelectric thin film can be any one of (0°, 0°, θ°), (90°, 90°, θ°), (0°, 90°, θ°), and (0°, θ°, 0°), where θ represents the angle. The thickness of the piezoelectric thin film can be in the range [200nm, 800nm].

[0070] In some possible implementations, the ratio of the thickness of the dielectric layer to the thickness of the piezoelectric film may be less than a preset threshold, which may be 1.2.

[0071] The longitudinal leakage surface acoustic wave (LSAW) resonator provided in this application, by employing a resonator combining a rotary-cut silicon carbide support substrate with a piezoelectric thin film, can reduce losses near the anti-resonance frequency without changing the sound velocity of the substrate material. This results in a wider ultra-low loss region for the resonator, leading to superior resonator and filter performance. Reducing the center-to-center spacing of the reflective gate electrodes in the reflective gate electrode array increases the reflection frequency range of the array, thereby suppressing spurious modes of the longitudinal leakage wave and improving resonator performance. Tilting the interdigital electrode array and the reflective gate electrode array on the piezoelectric thin film increases the Q value and suppresses spurious signals. Controlling the thickness of the interdigital electrodes prevents increased acoustic scattering in LL-SAW due to excessive electrode thickness, further reducing device losses. Adding a dielectric layer can further improve the resonator's Q value or compensate for device temperature stability.

[0072] The following describes a specific embodiment of a filter according to this application. Figure 9 This is a schematic diagram of another filter structure provided in an embodiment of this application. The filter may include multiple resonators, each of which can be... Figure 1 The structure shown can also be Figure 8 The structure shown. Multiple resonators can be cascaded or bridged with external capacitors and inductors. For example... Figure 9 As shown, multiple resonators can be cascaded with inductive components.

[0073] The longitudinal leakage surface acoustic wave filter provided in this application uses a resonator that combines a rotary-cut silicon carbide support substrate with a piezoelectric thin film. This reduces the loss near the anti-resonance frequency without changing the sound velocity of the substrate material, giving the resonator a wider ultra-low loss region and thus achieving better filter performance.

[0074] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, while this specification describes specific embodiments, other embodiments are also within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in the order shown in different embodiments and still achieve the desired results. Additionally, the processes depicted in the drawings do not necessarily require a specific order or sequence of connections to achieve the desired results; in some implementations, parallel processing of multiple tasks is possible or may be advantageous.

[0075] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, embodiments of apparatus and electronic devices are described simply because they are based on similar method embodiments; relevant parts can be referred to the descriptions of the method embodiments.

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A longitudinally leaking surface acoustic wave resonator, characterized in that, include: Support substrate; The supporting substrate is a rotary-cut silicon carbide substrate; The Euler angles of the cut surface and in-plane direction of the supporting substrate are (90°, 90°, 0°~50°); or; The Euler angles of the cut surface and in-plane direction of the supporting substrate are (0°, 70°~110°, 0°); A piezoelectric thin film is disposed on the supporting substrate; the material of the piezoelectric thin film is lithium niobate or lithium tantalate; the thickness of the piezoelectric thin film is within the range of [200nm, 800nm]; An electrode array disposed on the piezoelectric thin film; the electrode array includes an interdigitated electrode array and a reflective gate electrode array; The center-to-center spacing of the reflective grid electrodes in the reflective grid electrode array is less than or equal to the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array; The thickness of the interdigitated electrodes in the interdigitated electrode array is within the range of [60nm, 160nm]. The crystal Euler angles of the piezoelectric thin film are (0°, 0°, θ°), (90°, 90°, θ°), (0°, 90°, θ°), or (0°, θ°, 0°), where θ represents the angle.

2. The resonator according to claim 1, characterized in that, The reflective grating electrode array includes a first reflective grating electrode subarray and a second reflective grating electrode subarray; The first reflective gate electrode subarray is disposed at one end of the interdigital electrode array, and the second reflective gate electrode subarray is disposed at the other end of the interdigital electrode array; The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray is not equal to the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray; The center-to-center spacing of the reflective gate electrodes in the first reflective gate electrode subarray is less than or equal to the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array, and the center-to-center spacing of the reflective gate electrodes in the second reflective gate electrode subarray is less than or equal to the center-to-center spacing of the interdigitated electrodes in the interdigitated electrode array.

3. The resonator according to claim 1, characterized in that, The interdigitated electrode array and the reflective grid electrode array have an angle of inclination relative to the normal direction of the electrode array; The tilt angle is within a preset tilt angle range, which is [-10°, 10°].

4. The resonator according to claim 1, characterized in that, The resonator also includes: A dielectric layer disposed on the supporting substrate; The material of the dielectric layer is silicon oxide, silicon nitride, aluminum nitride, or aluminum oxide; The ratio of the thickness of the dielectric layer to the thickness of the piezoelectric film is less than a preset threshold; the preset threshold is 1.

2.

5. A filter, characterized in that, It includes multiple resonators, wherein the resonators are longitudinal leakage surface acoustic wave resonators as described in any one of claims 1-4; The multiple resonators are cascaded, bridged, or coupled based on a preset topology; or; The multiple resonators are cascaded or bridged with external capacitors and inductors.

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