Surface acoustic wave resonator design method for suppressing spurious signals based on polycrystalline metamaterial

Abstract

The invention relates to a surface acoustic wave resonator design method, and discloses a surface acoustic wave resonator design method for suppressing spurious signals based on a polycrystalline metamaterial, which comprises the following specific steps: S1, setting grain parameters by using a crystal plasticity modeling tool, and carrying out geometric modeling on a polycrystalline substrate which is made of the polycrystalline metamaterial; s2, the geometric model of the polycrystalline substrate is imported into electromagnetic simulation software, an elastic constant corresponding to each crystal grain is given, and the elastic constants are obtained through calculation of a random rotation matrix; and S3, selecting a material and constructing other structures of the surface acoustic wave resonator, thereby completing modeling of the surface acoustic wave resonator for suppressing spurious signals based on the polycrystalline metamaterial. The method has high flexibility and plasticity, and the designed resonator can effectively suppress spurious signals caused by a high-order mode. Researchers can optimize structural parameters in the design stage through the method, the number of experiments is reduced, and the Q value and the frequency selectivity are improved. The method is of great significance to improvement of device performance and 5G communication application.

Description

Technical Field

[0001] The present application relates to the field of surface acoustic wave devices and polycrystalline metamaterials, and mainly to a surface acoustic wave resonator design method for suppressing stray signals based on polycrystalline metamaterials. Background Art

[0002] Surface acoustic wave (SAW) resonators are an important part of filters and a key electronic component in modern mobile communication devices. In order to meet the multi-band application requirements in 5G communications, SAW resonators must provide good isolation between different frequency bands while maintaining the quality factor (Q) to avoid mutual interference. This requires that during the design process of SAW resonators, stray signals should be fully considered to ensure the quality and stability of signal transmission in each frequency band.

[0003] In recent years, SAW resonators based on heterostructures (piezoelectric film bonded on a supporting substrate) have been favored for their ability to improve the Q value. This technology confines the sound waves within the piezoelectric film through the acoustic impedance mismatch effect between the piezoelectric film and the supporting substrate (such as sapphire, silicon carbide), thereby significantly improving the Q value of the resonator. However, such heterostructures easily introduce inevitable bulk acoustic wave propagation modes, resulting in spurious responses. These spurious signals greatly limit the development of devices towards high frequency and system-level applications, and have become a core difficulty that needs to be solved urgently. Previous studies have shown that polycrystalline supporting substrates have a certain degree of suppressive effect on SAW spurious signals. However, there is no relevant theoretical design method to explore this in depth. At present, if we rely on repeated actual measurements to optimize the design of device characteristics, it will be very cumbersome and time-consuming.

[0004] Based on the above research background, this application invented a new simulation modeling method that can accurately simulate the acoustic wave propagation and stray signal suppression mechanism of heterostructure SAW resonators on polycrystalline support substrates. Through this method, researchers can optimize structural parameters in the design stage, reduce the number of experiments, and improve Q value and frequency selectivity. This is of great significance for improving device performance and 5G communication applications. Summary of the invention

[0005] In view of the problem that surface acoustic wave filters with heterogeneous bonding structures in the prior art generate stray signals and are difficult to suppress, the present application proposes a surface acoustic wave resonator design method for suppressing stray signals based on polycrystalline metamaterials.

[0006] According to one aspect of the present application, a method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals is proposed, and the specific steps are as follows:

[0007] S1. Using a crystal plasticity modeling tool, setting grain parameters, and performing geometric modeling of a polycrystalline substrate, wherein the material of the polycrystalline substrate is a polycrystalline metamaterial;

[0008] S2, importing the geometric model of the polycrystalline substrate into electromagnetic simulation software, and assigning elastic constants corresponding to each of the grains, wherein the elastic constants are obtained by random rotation matrix calculation;

[0009] S3. Select materials and construct the remaining structure of the surface acoustic wave resonator to complete the modeling of the surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals.

[0010] The grain boundaries of polycrystalline metamaterials can scatter electrons and phonons, and have the characteristics of low electrical conductivity, low thermal conductivity, strong and damage-resistant, and light. This method combines crystal plasticity tools with electromagnetic simulation software, and establishes a polycrystalline substrate surface acoustic wave resonator based on given structural parameters and calculated grain elastic matrix, and achieves the purpose of suppressing stray through the leakage of polycrystalline surface acoustic waves.

[0011] Furthermore, it also includes step S4: using the electromagnetic simulation software to perform electromagnetic simulation on the surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals. Through high-fidelity and high-flexibility electromagnetic simulation experiments, design parameters can be adjusted in time, design solutions can be continuously optimized, and product performance and system stability can be quickly verified, thereby reducing unnecessary trial and error and production costs and improving production efficiency.

[0012] Furthermore, in S1, the polycrystalline substrate is subjected to crystal geometric plasticity by Voronoi tessellation. The Voronoi tessellation can provide a method for accurately analyzing and predicting material deformation and damage. By means of the Voronoi tessellation, the grain shape of the sample before and after deformation and the inhomogeneity of deformation can be truly represented, thereby accurately and efficiently performing geometric modeling of the polycrystalline substrate.

[0013] Furthermore, in S1, the grain parameters include the number of grains, the average grain size, the grain size distribution, the grain sphericity and the length, width and height of the polycrystalline substrate. The grain parameters are directly related to the mechanical properties, corrosion resistance and thermal stability of the substrate material. Setting detailed and reasonable grain parameters and suitable substrate materials and sizes can ensure the stability of the substrate and the entire resonator.

[0014] Preferably, the grain size distribution includes one of normal distribution, lognormal distribution, Dirac distribution and Lorentz distribution. Multiple grain size distribution modes help to improve the flexibility of grain parameter setting, and the appropriate grain size distribution mode can be selected according to specific conditions.

[0015] Preferably, the grain sphericity distribution includes one of normal distribution, lognormal distribution, Dirac distribution and Lorentz distribution. A variety of grain sphericity distribution modes help to improve the flexibility of grain parameter setting, and a suitable grain sphericity distribution mode can be selected according to specific conditions.

[0016] Furthermore, in S2, the detailed steps of generating the grain elastic constants are as follows:

[0017] S21, using three random variables to generate a random rotation matrix A through a two-step method,

[0018]

[0019] S22, calculating the transformation matrix Aε of the stress tensor from the random rotation matrix A,

[0020]

[0021] S23, calculating the elastic matrix C' of each grain by using the transformation matrix Aε,

[0022]

[0023] Among them, is the transposed matrix of the transformation matrix Aε, and C is the elastic matrix of the single crystal.

[0024] Furthermore, in S3, the parameters that need to be set for constructing the remaining structures of the surface acoustic wave resonator include the number of layers, material, geometry, metallization rate, length, width and thickness of the electrodes, and the material, length, width and thickness of the piezoelectric film.

[0025] According to a second aspect of the present invention, a surface acoustic wave resonator for suppressing stray signals based on polycrystalline metamaterials is proposed.

[0026] Furthermore, the surface acoustic wave resonator is a heterogeneous bonding structure, which includes metal interdigital electrodes, the piezoelectric film and the polycrystalline substrate from top to bottom. The heterogeneous bonding structure can cause the stray signals caused by the high-order mode to leak into the polycrystalline substrate in the form of body waves.

[0027] Compared with the prior art, the beneficial effects of this application are:

[0028] Compared with the traditional bonding structure, the heterogeneous bonding structure based on the polycrystalline substrate adopted in this application can effectively suppress the stray signals caused by the high-order mode through the leakage effect of the polycrystalline substrate. This design is simple and easy to implement, and the method of suppressing stray signals is simple. It has high flexibility and plasticity, and is suitable for filter design in various application scenarios. It not only further improves the performance of the surface acoustic wave filter, but also expands the range of material selection in the design process of the surface acoustic wave resonator, providing more possibilities for manufacturing stray-free filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and are used together with the description to explain the principles of the present invention. It will be easy to recognize other embodiments and many expected advantages of the embodiments because they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale with each other. The same reference numerals refer to corresponding similar parts.

[0030] Figure 1 A schematic flow chart of a method for modeling and simulating a surface acoustic wave resonator for suppressing stray signals based on a polycrystalline substrate according to an embodiment of the present invention is shown;

[0031] Figure 2 shows a statistical distribution diagram of grain size of a polycrystalline metamaterial generated according to a specific embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a model structure of a surface acoustic wave resonator based on a polycrystalline metamaterial according to a specific embodiment of the present invention is shown;

[0033] Figure 4 A graph showing the admittance and conductance curves of a surface acoustic wave resonator based on a polycrystalline metamaterial according to a specific embodiment of the present invention is shown;

[0034] Figure 5 shows mode shapes of a surface acoustic wave resonator based on a polycrystalline metamaterial at different frequencies according to a specific embodiment of the present invention;

[0035] Figure 6 A comparison diagram of the simulation results of the admittance of a surface acoustic wave resonator based on a polycrystalline metamaterial with different grain sizes and a single crystal sapphire substrate resonator according to a specific embodiment of the present invention is shown;

[0036] Figure 7 A temperature characteristic curve of a surface acoustic wave resonator based on a polycrystalline metamaterial according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0037] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] Figure 1 A schematic flow chart of a method for modeling and simulating a surface acoustic wave resonator for suppressing stray signals based on a polycrystalline substrate according to an embodiment of the present invention is shown.

[0040] The present invention discloses a surface acoustic wave resonator for suppressing stray signals based on polycrystalline metamaterials, and the design method specifically comprises the following steps:

[0041] A1. Use the crystal plasticity modeling tool Neper to set the grain parameters and perform geometric modeling of the polycrystalline substrate. The grain parameters include:

[0042] The number of grains is set to 67, and the grain size follows a log-normal distribution, such as Figure 2 As shown, the expectation (i.e., average grain size) and variance of the set log-normal distribution are 6.5 and 0.5 respectively, the set sphericity distribution is the log-normal distribution expectation and variance are 0.18 and 0.09 respectively, the material of the polycrystalline substrate is the polycrystalline metamaterial, the substrate period length is 43.31 μm, the width is 15 μm, and the height is 15 μm;

[0043] A2. Import the geometric model of the polycrystalline substrate into the electromagnetic simulation software COMSOL, use the numerical calculation tool MATLAB, adopt the calculation method of random rotation matrix, obtain the elastic constant of each grain, and assign the corresponding elastic constant to each grain. The detailed steps of generating the grain elastic constant are as follows:

[0044] A21. Use three random variables to generate a random rotation matrix A in a two-step method: first, use a random variable in the computer to determine the rotation axis of the cylindrical coordinate system, and use another random variable to determine the rotation angle; then convert this information into a quaternion representation, where the real part of the quaternion is half of the cosine value, and the imaginary part is the product of half of the sine value and the rotation axis component; finally, according to the definition of the quaternion, the corresponding orthogonal matrix is ​​calculated, which is the random rotation matrix A:

[0045]

[0046] A22. The transformation matrix Aε of the stress tensor is calculated by the random rotation matrix A. The transformation formula is:

[0047]

[0048] A23. The elastic matrix C' of each grain after rotation is calculated from the elastic matrix of the single crystal and the transformation matrix Aε of the stress tensor. The calculation formula is:

[0049]

[0050] in, is the transposed matrix of the transformation matrix Aε, and C is the elastic matrix of the single crystal.

[0051] A3. Select materials and construct the rest of the SAW resonator structure to complete the modeling of the SAW resonator based on polycrystalline metamaterials to suppress stray signals. The schematic diagram of the structure is shown in the figure. Figure 3 As shown, the surface acoustic wave resonator structure consists of metal interdigital electrodes composed of periodically arranged metal electrodes, a piezoelectric film for acoustic-electric conversion, and a polycrystalline substrate with an almost semi-infinite length. The metal electrode is a single layer, made of pure aluminum, with a thickness of T e About 0.37μm, width W e The metal interdigitated electrodes have a rectangular geometry and an electrode spacing P of about 2.17 μm. The piezoelectric film material is a 42°YX-tangential lithium tantalate piezoelectric crystal (42°YX-LiTaO3) with a thickness of T piezo 3μm.

[0052] A4. Use electromagnetic simulation software COMSOL to simulate the surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals. The results are as follows Figure 4-7 shown.

[0053] Figure 4 is a graph of the admittance and conductance of the surface acoustic wave resonator based on the polycrystalline metamaterial of the present invention, Figure 5 Figure 1 is a vibration diagram of the surface acoustic wave resonator based on polycrystalline metamaterials at different frequencies of the present invention. Figure 4 It can be seen that the surface acoustic wave resonator based on polycrystalline metamaterials has a good admittance response curve and a relatively smooth response outside the passband. The resonant frequency of the resonator is about 899MHz, and the anti-resonant frequency is about 934MHz. Figure 4 The conductivity curve and Figure 5 From the vibration mode diagram, we can know that at the resonance of 899MHz surface acoustic wave, horizontal shear wave is excited and the acoustic energy is well bound to the piezoelectric surface layer. At the frequencies of 1092MHz and 1605MHz, the impedance matching caused by the different orientations of polycrystalline makes the acoustic energy leak into the polycrystalline substrate, thus dispersing the energy of the surface layer and weakening the interference of stray signals.

[0054] Figure 6This is a comparison chart of the admittance simulation results of the surface acoustic wave resonator based on the polycrystalline metamaterial of the present invention with that of the single crystal sapphire substrate resonator with different grain sizes. It can be seen from the admittance simulation curve in the figure that the traditional surface acoustic wave resonator based on the single crystal sapphire substrate has obvious spurious emission near the frequencies of 1130MHz and 1400MHz, while the surface acoustic wave resonator with a polycrystalline substrate bonding structure proposed in the present application greatly reduces the out-of-band spurious emission through the leakage of the polycrystalline substrate and has a significant suppression effect on different grain sizes.

[0055] Figure 7 This is a temperature characteristic curve diagram of the surface acoustic wave resonator based on polycrystalline metamaterials of the present invention. It can be seen from the figure that the temperature coefficient of the resonator based on polycrystalline heterogeneous bonding is -27.6ppm / K at resonance, and the temperature coefficient is -47.1ppm / K at anti-resonance, which indicates that the surface acoustic wave resonator based on polycrystalline metamaterials designed in the present application can not only suppress stray signals, but also has small changes in center frequency at different temperatures, high frequency stability, and good performance consistency, which can ensure that the equipment can work reliably in a wide temperature range.

[0056] The above describes the specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0057] In the description of the present application, it should be understood that the terms "upper", "lower", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The wording 'comprising' does not exclude the presence of elements or steps not listed in the claims. The simple fact that certain measures are recorded in mutually different dependent claims does not indicate that a combination of these measures cannot be used for improvement. Any reference symbols in the claims should not be interpreted as limiting the scope.

Claims

1. A method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals, characterized in that: The specific steps are as follows: S1. Using a crystal plasticity modeling tool, setting grain parameters, and performing geometric modeling of a polycrystalline substrate, wherein the material of the polycrystalline substrate is a polycrystalline metamaterial; S2, importing the geometric model of the polycrystalline substrate into electromagnetic simulation software, and assigning elastic constants corresponding to each of the grains, wherein the elastic constants are obtained by random rotation matrix calculation; S3. Select materials and construct the remaining structure of the surface acoustic wave resonator to complete the modeling of the surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals.

2. The method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals according to claim 1, characterized in that: The method further comprises step S4: using the electromagnetic simulation software to perform electromagnetic simulation on the surface acoustic wave resonator for suppressing stray signals based on the polycrystalline metamaterial.

3. The method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals according to claim 1, characterized in that: In S1, the polycrystalline substrate is subjected to crystal geometry plasticity through a Voronoi tessellation method.

4. The method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals according to claim 1, characterized in that: In S1, the grain parameters include the number of grains, the average size of the grains, the grain size distribution, the sphericity of the grains and the length, width and height of the polycrystalline substrate.

5. The method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals according to claim 4, characterized in that: The grain size distribution includes one of a normal distribution, a log-normal distribution, a Dirac distribution and a Lorentz distribution.

6. The method for designing a surface acoustic wave resonator for suppressing stray signals based on polycrystalline metamaterials according to claim 4, characterized in that: The grain sphericity distribution includes one of normal distribution, lognormal distribution, Dirac distribution and Lorentz distribution.

7. The method for designing a surface acoustic wave resonator for suppressing stray signals based on polycrystalline metamaterials according to claim 1, characterized in that: In S2, the detailed steps for generating the grain elastic constants are as follows: S21, using three random variables to generate a random rotation matrix A through a two-step method, S22, calculating the transformation matrix Aε of the stress tensor from the random rotation matrix A, S23, calculating the elastic matrix C' of each grain by using the transformation matrix Aε, in, is the transposed matrix of the transformation matrix Aε, and C is the elastic matrix of the single crystal.

8. The method for designing a surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals according to claim 1, characterized in that: In S3, the parameters that need to be set for constructing the remaining structures of the surface acoustic wave resonator include the number of layers, material, geometry, metallization rate, length, width and thickness of the electrodes, and the material, length, width and thickness of the piezoelectric film.

9. A surface acoustic wave resonator based on polycrystalline metamaterials to suppress stray signals, characterized in that: The surface acoustic wave resonator is designed by the design method according to any one of claims 1 to 8.

10. The surface acoustic wave resonator based on polycrystalline metamaterials for suppressing stray signals according to claim 9, characterized in that: The surface acoustic wave resonator is a heterogeneous bonding structure, which comprises metal interdigital electrodes, the piezoelectric film and the polycrystalline substrate from top to bottom.

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