Bulk acoustic wave delay line two-dimensional simulation method based on COMSOL Multiphysics

Abstract

The invention discloses a two-dimensional simulation method for a bulk acoustic wave delay line based on COMSOL Muliphysics. The method comprises the following steps: S1, establishing a two-dimensional geometric model of the bulk acoustic wave delay line by adopting a geometric module in C0MS0L Multiphysics simulation software; s2, performing region division on the geometric model, and setting material parameters; s3, setting parameters of a solid mechanics physical field module and an electrostatic physical field, performing grid division on each region, setting an event physical field, and correspondingly setting the parameters of each physical field module; s4, setting multi-physical field coupling; and S5, calculating and solving to obtain a simulation result of the bulk acoustic wave delay line. The vibration mode and the S parameter are determined through analog simulation of the bulk acoustic wave delay line, and the method can shorten the time cost for actual use and reduce the manufacturing cost.

Description

Technical Field

[0001] The present invention belongs to the field of microacoustic devices, and particularly relates to a two-dimensional simulation method of a bulk acoustic wave delay line based on COMSOL Multiphysics. Background Art

[0002] Bulk acoustic wave delay lines have the advantages of high operating frequency, small volume, small mass, non-dispersive, low insertion loss and good attenuation stability, and are widely used in military electronic systems such as radar, aircraft, missile target signal simulation, electronic countermeasure, electronic ignition, frequency discrimination, moving target indication, and altimeter calibration. In a BAW delay line, a microwave electrical signal is transmitted to an input transducer, and through the inverse piezoelectric effect of the transducer, the electrical signal is converted into an acoustic signal and propagates in the sound transmission medium. When the acoustic signal reaches the output transducer, the acoustic signal is converted into an electrical signal through the piezoelectric effect of the transducer and output. Since the speed of the electrical signal is 10 3 ~10 4 times that of the acoustic wave transmission speed, electrical signal delay is achieved.

[0003] In the actual R & D process, directly preparing a bulk acoustic wave delay line involves multiple links such as material procurement, equipment processing, and experimental testing. These processes are costly and time-consuming. Using COMSOL Multiphysics for simulation can quickly verify the design and performance in a virtual environment, greatly saving the time and cost of physical preparation and testing. Through simulation, the structural parameters can be easily modified, and new simulation results can be obtained within seconds to minutes. Compared with directly preparing and then discovering design defects, simulation can be quickly iterated and optimized to help find the best design scheme, thereby improving the R & D efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a two-dimensional simulation method of a bulk acoustic wave delay line based on COMSOL Multiphysics. By simulating and emulating the bulk acoustic wave delay line, the vibration mode and S parameters of the designed bulk acoustic wave delay line are determined. This method can shorten the time cost and reduce the manufacturing cost.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A two-dimensional simulation method of a bulk acoustic wave delay line based on COMSOL Multiphysics includes the following steps:

[0007] S1. Establish a two-dimensional geometric model of the bulk acoustic wave delay line using the geometric module in the COMSOL Multiphysics simulation software;

[0008] S2. Divide the region of the geometric model and set the material parameters;

[0009] Specifically, the upper and lower electrode domains, piezoelectric domains, perfectly matched layer domains, and acoustic transmission medium domains are divided according to the geometric model in S1; physical interfaces are selected according to the actual working conditions, and corresponding electrode, piezoelectric, and acoustic transmission medium materials are set.

[0010] S3. Set the parameters of the solid mechanics physical field module and the electrostatic physical field, perform mesh division on each region, set the event physical field, and perform corresponding settings on the parameters of each physical field module; Divide, set the event physical field, and perform corresponding settings on the parameters of each physical field module;

[0011] S4. Set the multi-physics coupling;

[0012] S5. Calculate and solve to obtain the simulation results of the bulk acoustic wave delay line.

[0013] In a specific case, in step S3, the piezoelectric thin film and the piezoelectric acoustic transmission medium satisfy the Newton's equation of motion, the quasi-static Gauss's equation, and the piezoelectric constitutive relation:

[0014]

[0015] Among them, T, S, D, u, E, ρ, c, e, and ε represent the stress tensor, strain tensor, electric displacement vector, displacement vector, electric field strength vector, medium density, elastic constant, piezoelectric constant, and dielectric constant respectively.

[0016] In a specific case, in step S3, the electrode domain satisfies the elastic constitutive relation:

[0017]

[0018] Among them, T, D, u, E, ρ, c, and ε represent the stress tensor, electric displacement vector, displacement vector, electric field strength vector, medium density, elastic constant, and dielectric constant respectively.

[0019] In a specific case, the multi-physics coupling in step S4 is piezoelectric effect coupling.

[0020] The two-dimensional simulation method of the bulk acoustic wave delay line based on COMSOL Multiphysics in the present invention obtains the relationship between the frequency, S parameters, and vibration modes through the simulation of the bulk acoustic wave delay line. It can help provide the frequency and S parameter values for bulk acoustic wave delay lines of different lengths and widths, and provide assistance for the R & D process. Description of the Drawings

[0021] Figure 1 It is a flow chart of the simulation method of the bulk acoustic wave delay line based on COMSOL Mulitphysics in the present invention.

[0022] Figure 2Geometric model of the bulk acoustic wave delay line established for the specific embodiment of the present invention.

[0023] Figure 3 Schematic diagram of the regional division of the geometric model established for the specific embodiment of the present invention.

[0024] Figure 4 Schematic diagram of the mesh division of the geometric model established for the specific embodiment of the present invention.

[0025] Figure 5 Vibration mode calculated for the specific embodiment of the present invention.

[0026] Figure 6 S-parameter curve graph calculated for the specific embodiment of the present invention. Specific implementation manner

[0027] The present invention will be described in detail below through specific embodiments in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0028] The object of the present invention is to provide a two-dimensional simulation method for a bulk acoustic wave delay line based on COMSOL Multiphysics, including the following steps: Step S1: Use the geometric module in the COMSOL Multiphysics simulation software to establish a two-dimensional geometric model of the bulk acoustic wave delay line.

[0029] Step S2: Divide the region of the geometric model and set the material parameters. Divide the upper and lower electrode domains, piezoelectric domain, perfectly matched layer domain, and sound transmission medium domain according to the geometric model in S1; select the physical interface according to the actual working conditions and set the corresponding electrode, piezoelectric, and sound transmission medium materials.

[0030] S3: Set the parameters of the solid mechanics physical field module and the electrostatic physical field, perform mesh division on each region, set the event physical field, and perform corresponding settings on the parameters of each physical field module.

[0031] According to the actual use situation of the bulk acoustic wave delay line, set the corresponding solid mechanics field and electrostatic field for the bulk acoustic wave delay line, perform parameter definition, and set the relative permittivity of the piezoelectric material, elastic matrix, Young's modulus, and Poisson's ratio of the sound transmission medium and the electrode according to the actual material parameters.

[0032] Among them, in step S3, the piezoelectric thin film and the piezoelectric sound transmission medium satisfy the Newtonian motion equation, the quasi-static Gauss equation

[0033] and the piezoelectric constitutive relationship:

[0034]

[0035] ​Among them, T, S, D, u, E, ρ, c, e, ε represent the stress tensor, strain tensor, electric displacement vector, displacement vector, electric field strength vector, medium density, elastic constant, piezoelectric constant, and dielectric constant, respectively.

[0036] Among them, in step S3, the electrode domain satisfies the elastic constitutive relation:

[0037]

[0038] Among them, T, D, u, E, ρ, c, ε represent the stress tensor, electric displacement vector, displacement vector, electric field strength vector, medium density, elastic constant, and dielectric constant, respectively.

[0039] S4. Set up multi-physics coupling, and the multi-physics coupling is piezoelectric effect coupling.

[0040] S5. Calculate and solve to obtain the simulation results of the bulk acoustic wave delay line.

[0041] The following are the specific implementation cases of the present invention.

[0042] In this example, the simulation process is as shown in the flowchart Figure 1 as follows:

[0043] Use COMSOL Multiphysics software with version number 6.1.

[0044] From top to bottom, successively establish rectangles with lengths and widths of 500μm×0.2μm, 1000μm×9.5μm, 1000μm×0.2μm, 1000μm×100μm, 1000μm×0.2μm, 1000μm×9.5μm, and 500μm×0.2μm that are tightly connected in the width direction, and combine them into an axisymmetric figure. Then, additionally divide rectangles with lengths and widths of 50μm×119μm on the left and right sides inside the geometric part with a length of 1000μm. As Figure 2 shown.

[0045] In this implementation case, in step S2, the geometric model is divided into regions, as Figure 3 shown. The set material parameters are as follows in specific technical steps:

[0046] Divide the two-dimensional model into input and output upper and lower electrode regions, perfectly matched layer regions, sound transmission medium regions, and piezoelectric regions.

[0047] Add materials. Add molybdenum provided by the COMSOL software in the electrode region, add AlN provided by the COMSOL software in the piezoelectric region, add SiO2 provided by the COMSOL software in the sound transmission medium region, and set the perfectly matched layer region as the perfectly matched layer in the fictitious domain.

[0048] In this embodiment, in step S3, set the initial parameters of the solid mechanics physical field and the electrostatic physical field, and the mesh division is as Figure 4 . The specific steps are as follows:

[0049] (1) Set the solid mechanics physical field. In the solid mechanics setting window, enter 20 [μm] in the thickness column, select the piezoelectric region for the domain selection of the piezoelectric material, and add a fixed constraint to the outer layer of the perfectly matched layer.

[0050] (2) Set the electrostatic physical field. In the solid mechanics setting window, enter 20 [μm] in the thickness column, set a grounded boundary on the side of the lower electrode close to the piezoelectric region, set a terminal boundary on the input upper electrode with a terminal power of 1, and set a terminal boundary on the output upper electrode with a terminal power of 0.

[0051] In this embodiment, the specific steps for setting the multi-physics coupling in step S4 are:

[0052] Click on multi-physics coupling in the physics field menu, and select the piezoelectric effect under the domain menu.

[0053] In this embodiment, step S5: Calculate and solve to obtain the result of the ablation needle ablating liver tissue. The specific technical steps are as follows:

[0054] (1) Click on Step 1: Frequency Domain under the Study 1 node in the Model Builder window. In the frequency domain setting window, locate to the Study Settings column, and enter "range(100,0.1,1000)[MHz]" in the Frequency text box.

[0055] (2) Click on the Calculate option on the Settings page to start the calculation.

[0056] (3) The calculated vibration modes corresponding to the input frequencies are as Figure 5 and the S-parameter curve graph is as Figure 6 .

Claims

1. A two-dimensional simulation method of bulk acoustic wave delay line based on COMSOL Multiphysics, characterized in that , including the following steps: S1. Use the geometry module in COMSOL Multiphysics simulation software to establish a two-dimensional geometric model of the bulk acoustic wave delay line; S2, divide the area of ​​the geometric model and set material parameters; Specifically, the upper and lower electrode domains, piezoelectric domain, perfectly matched layer domain and sound transmission medium domain are divided according to the geometric model in S1; the physical interface is selected according to the actual working conditions and the corresponding electrode, piezoelectric and sound transmission medium materials are set. S3, setting parameters of solid mechanics physics field module and electrostatic physics field, meshing each area, setting event physics field, and setting parameters of each physics field module accordingly; S4. Setting up multi-physics coupling; S5. Calculate and solve to obtain the simulation results of the bulk acoustic wave delay line.

2. The two-dimensional simulation method of bulk acoustic wave delay line according to claim 1 is characterized in that , wherein the piezoelectric film and the piezoelectric sound transmission medium in step S3 satisfy the Newtonian motion equation, the quasi-static Gaussian equation and the piezoelectric constitutive relationship: Among them, T, S, D, u, E, ρ, c, e, and ε represent stress tensor, strain tensor, electric displacement vector, displacement vector, electric field intensity vector, dielectric density, elastic constant, piezoelectric constant, and dielectric constant, respectively.

3. The two-dimensional simulation method of bulk acoustic wave delay line according to claim 1 is characterized in that , where the electrode domain in step S3 satisfies the elastic constitutive relation: Among them, T, D, u, E, ρ, c, and ε represent stress tensor, electric displacement vector, displacement vector, electric field intensity vector, dielectric density, elastic constant, and dielectric constant, respectively.

4. The two-dimensional simulation method of bulk acoustic wave delay line according to claim 1 is characterized in that , the multi-physical field coupling in step S4 is piezoelectric effect coupling.

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