Lithium niobate acoustic superlattice bulk acoustic wave resonator device based on inclined domain structure and design method of lithium niobate acoustic superlattice bulk acoustic wave resonator device

Abstract

The invention discloses a lithium niobate acoustic superlattice bulk acoustic wave resonator device based on an inclined domain structure and a design method thereof.The bulk acoustic wave resonator device comprises an upper surface electrode, a lithium niobate acoustic superlattice and a lower surface electrode which are sequentially stacked from top to bottom, the lithium niobate acoustic superlattice comprises positive domain regions and negative domain regions which are alternately arranged, and the positive domain regions and the negative domain regions are alternately arranged. And the positive domain region and the negative domain region are inclined domains. The invention also provides a design method of the bulk acoustic wave resonance device, which comprises the following steps of: firstly, acquiring simulation parameters through numerical simulation, and then designing different cut types of lithium niobate acoustic superlattices with positive domain regions and negative domain regions which are periodically and alternately arranged and inclined structures according to the simulation parameters; and finally, respectively selecting proper electrodes on the upper surface and the lower surface of the lithium niobate acoustic superlattice to form the bulk acoustic wave resonator. The bulk acoustic wave resonator is simple in structure, and has more working resonance modes and a higher electromechanical coupling coefficient.

Description

Technical Field

[0001] The invention relates to a bulk acoustic wave device and a design method thereof, and in particular to a lithium niobate acoustic superlattice bulk acoustic wave resonator device based on a tilted domain structure and a design method thereof. Background Art

[0002] RF acoustic devices can achieve signal processing by converting between RF signals and high-frequency sound waves, and have been widely used in mobile communications, industrial applications, national defense and military and other fields. Innovations in the RF field such as 5G and the Internet of Things have increased the demand for high-performance, passive and wide-band RF filters and resonators. Bulk acoustic wave acoustic devices have been proven to be a reliable solution for RF signal processing from low to high frequencies. The increasingly rich application scenarios also require more bulk acoustic wave devices of different types, different characteristics and better performance.

[0003] The currently widely used bulk acoustic wave devices are composed of a piezoelectric layer and upper and lower films. They have the advantages of small size, suitable for high operating frequencies, low insertion loss, and high power capacity. However, they also have limitations such as low electromechanical coupling coefficient and complex process. Moreover, for conventional bulk wave resonant devices, higher operating frequencies can generally only be achieved by reducing the thickness of the piezoelectric layer. The electromechanical coupling coefficient also depends only on the properties of the material itself and is difficult to adjust.

[0004] Lithium niobate is C 3v Symmetrical negative uniaxial ferroelectric crystals have two antiparallel spontaneous polarization orientations in their ferroelectric phase, that is, there are only two ferroelectric domains with opposite spontaneous polarization directions along the z-axis. Lithium niobate acoustic superlattice is an artificial microstructure material with two ferroelectric domains arranged alternately, and second-order tensors such as piezoelectric coefficients are artificially modulated, while physical quantities such as wave velocity and refractive index remain uniform overall. Since the acoustic superlattice itself has piezoelectric effect, stress and strain will be generated in the superlattice under the action of electric field, and stress and strain will generate polarization electric field. Due to the existence of superlattice microstructure, the interaction properties between acoustic superlattice and electromagnetic waves are very different from those of uniform crystals. Each domain boundary in the acoustic superlattice will also become an excitation wave source of stress wave, and the operating frequency of the acoustic resonator made of it is inversely proportional to the distribution period of piezoelectric coefficient. Acoustic superlattice can use such properties to realize new bulk acoustic wave devices with rich functions.

[0005] Unlike ordinary isotropic materials, lithium niobate is an anisotropic material, and its crystal physical properties are closely related to its cut shape. Unlike other isotropic piezoelectric materials, the acoustic wave performance of lithium niobate is closely related to its cut direction and the direction of acoustic wave propagation. Most traditional lithium niobate acoustic superlattice body acoustic wave devices are Z-cut lithium niobate acoustic superlattices, which do not fully utilize lithium niobate with different cut shapes to achieve electroacoustic control. The electromechanical coupling coefficient of lithium niobate acoustic superlattices with this cut shape is low and the acoustic resonance mode that can be used is relatively single. Summary of the invention

[0006] In view of the problems existing in the prior art, the object of the present invention is to provide a lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure with richer resonance modes and higher electromechanical coupling coefficient, and a design method thereof.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure comprises an upper surface electrode, a lithium niobate acoustic superlattice and a lower surface electrode stacked in sequence from top to bottom, wherein the lithium niobate acoustic superlattice comprises alternatingly arranged positive domain regions and negative domain regions, the piezoelectric coefficient of the positive domain region is positive, the piezoelectric coefficient of the negative domain region is negative, both the positive domain region and the negative domain region are tilted domains, and the tilt angles θ∈(0°, 90°)∪(90°, 180°) between the positive domain region and the negative domain region and the electrode surface.

[0009] A design method for the above-mentioned lithium niobate acoustic superlattice body acoustic wave resonator device based on the tilted domain structure includes:

[0010] Step (1), obtaining simulation parameters of a lithium niobate acoustic superlattice body acoustic wave resonator device that can achieve target performance, including physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device and the tilt angle θ and ferroelectric domain distribution period T of the lithium niobate acoustic superlattice;

[0011] Step (2), selecting a lithium niobate substrate of a corresponding cut type according to the simulation parameters of step (1);

[0012] Step (3), calculate the coercive field of lithium niobate according to the tilt angle θ:

[0013] E c (θ) = E c (90°) / cos(θ-90°)

[0014] In the formula, E c (θ) Coercive field of lithium niobate when the tilt angle is θ, E c (90°) represents the coercive field of lithium niobate when the tilt angle is 90°:

[0015] Step (4), according to the ferroelectric domain distribution period T, the thickness H of lithium niobate in the simulation parameters and the coercive field E of lithium niobate when the tilt angle is θ c (θ) selecting a polarization method for making the lithium niobate substrate into a lithium niobate acoustic superlattice;

[0016] Step (5), selecting electrode materials that meet the simulation parameters on the upper and lower surfaces of the lithium niobate acoustic superlattice to form an upper surface electrode and a lower surface electrode respectively.

[0017] Furthermore, step (1) specifically includes:

[0018] Step (1.1), setting preliminary simulation parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device, including physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device and the ferroelectric domain distribution period T of the lithium niobate acoustic superlattice;

[0019] Step (1.2), using the Euler angle transformation (α, β, γ) of the ZXZ rotation method to transform the material coordinate system of the Z-cut lithium niobate into the material coordinate system of the ZX-cut lithium niobate with an angle of θ, wherein the Euler angle of the positive domain region transformation is (0°, θ+90°, 0°), and the Euler angle of the negative domain region transformation is (0°, θ-90°, 0°);

[0020] Step (1.3), establishing a geometric model of a lithium niobate acoustic superlattice body acoustic wave resonator device in a simulation software, setting the physical size parameters of the geometric model to the physical size parameters of the simulation parameters, setting the ferroelectric domain distribution period of the lithium niobate acoustic superlattice in the geometric model to T in the simulation parameters, and meshing the geometric model;

[0021] Step (1.4), perform frequency domain calculation based on the meshed geometric model, draw the admittance curve and vibration mode diagram according to the frequency domain calculation results, and calculate the electrical coupling coefficient and resonant frequency;

[0022] Step (1.5), determine whether the electromechanical coupling coefficient is higher than the threshold, whether the resonant frequency is within the resonant frequency range, and whether the parasitic mode is suppressed; if all the judgment results are yes, output the simulation parameters at this time; otherwise, readjust the simulation parameters and return to execute step (1.2).

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention can generate new resonant modes, thereby utilizing new resonant frequencies. Figure 2As shown in the figure, a new A0 mode Lamb wave working resonance mode appears in the 60° tilt angle lithium niobate, with a resonant frequency of 397MHz, an anti-resonant frequency of 399MHz, and an electromechanical coupling coefficient of 1.2%. However, the traditional non-tilted domain structure lithium niobate superlattice does not have an A0 mode Lamb wave working resonance mode.

[0025] 2. The present invention can increase the electromechanical coupling coefficient of the resonant mode. Figure 5 As shown in the figure, the S0 mode Lamb wave working resonant mode frequency of the conventional non-tilted domain structure lithium niobate acoustic superlattice is 610MHz, the anti-resonant frequency is 614MHz, and the electromechanical coupling coefficient is 1.6%; while the resonant frequency of the 60° tilted domain structure lithium niobate acoustic superlattice in this resonant mode is 586MHz, the anti-resonant frequency is 621MHz, and the electromechanical coupling coefficient is 15.1%. While the resonance effect is improved, the electromechanical coupling coefficient is significantly improved.

[0026] 3. The present invention can suppress the original resonance mode. Figure 8 As shown, the S2 mode Lamb wave working resonance mode of the non-tilted domain structure lithium niobate acoustic superlattice is 1186MHz, the anti-resonance frequency is 1188MHz, and the electromechanical coupling coefficient is 0.4%. Here, the 60° tilted domain structure lithium niobate acoustic superlattice has a better suppression effect on this resonance mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure provided by the present invention;

[0028] Figure 2 It is the simulated admittance curve of lithium niobate acoustic superlattice at θ=60° and θ=90° in the case of A0 mode Lamb wave working resonant mode;

[0029] Figure 3 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=90° and the resonance frequency is 397MHz;

[0030] Figure 4 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=60° and the resonance frequency is 397MHz;

[0031] Figure 5 It is the simulated admittance curve of lithium niobate acoustic superlattice at θ = 60° and θ = 90° under the condition of S0 mode Lamb wave coupling working resonant mode;

[0032] Figure 6 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=90° and the resonant frequency is 610MHz;

[0033] Figure 7is the vibration mode diagram of lithium niobate acoustic superlattice when θ=60° and the resonant frequency is 586MHz;

[0034] Figure 8 It is the simulated admittance curve of lithium niobate acoustic superlattice at θ = 60° and θ = 90° in the case of S2 mode Lamb wave working resonant mode;

[0035] Fig. 9 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=90° and the resonant frequency is 1186MHz;

[0036] Fig.10 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=60° and the resonant frequency is 1201MHz;

[0037] Fig.11 It is the simulated admittance curve of lithium niobate acoustic superlattice at θ = 30° in the case of S2 mode Lamb wave working resonant mode;

[0038] Fig.12 This is the vibration mode diagram of lithium niobate acoustic superlattice when θ=30° and the resonant frequency is 1128MHz. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0040] Before introducing the embodiments of the present invention, the following explanation is first made: lithium niobate piezoelectric crystal is an anisotropic material, which leads to different acoustic modes in the piezoelectric crystal The propagation characteristics are not the same. Therefore, when studying lithium niobate crystals, it is necessary to first explain which crystal plane is "cut" for research, that is, the cut type of the lithium niobate crystal. The initial parameters of the material properties of lithium niobate crystals can be expressed by the relative position of a coordinate system (X, Y, Z), which is called the material coordinate system. Corresponding to this is a geometric coordinate system that reflects the orientation of the material in real space, which is expressed by the relative position of (x, y, z). The normal, unrotated lithium niobate crystal coordinate system is Z-cut lithium niobate. ZX-cut lithium niobate with an angle of θ is corresponding to the lithium niobate crystal cutting plane with the normal direction of the Z axis rotating counterclockwise around the X axis by θ. At this time, the lithium niobate crystal coordinate system has rotated relative to the default geometric coordinate system. Lithium niobate can only spontaneously polarize along the Z-axis direction of the material coordinate system to produce ferroelectric domains, thereby producing a tilted domain structure rotated by θ relative to the z-axis of the geometric coordinate system. At this time, the angle between the domain interface and the electrode plane is θ.

[0041] During the simulation process, the material coordinate system of Z-cut lithium niobate is converted to the material coordinate system of ZX-cut lithium niobate with an angle of θ by using the Euler angle transformation of the ZXZ rotation method. The definition of the Euler angles (α, β, γ) using the ZXZ rotation method is: starting from the spatial coordinate system (x, y, z), first rotate α counterclockwise around the z axis to obtain the coordinate system (x1, y1, z1), then rotate β counterclockwise around the x1 axis to obtain the coordinate system (x2, y2, z2), and finally rotate counterclockwise around the z2 axis to obtain the material coordinate system (X, Y, Z). The transformation matrix defined by the Euler angle can convert the vector (v X ,v Y ,v Z ) is converted to a vector (v) in the spatial coordinate system (x, y, z) x ,v y ,v z ), expressed as:

[0042]

[0043] The electromechanical coupling coefficient represents the conversion efficiency between mechanical energy and electrical energy. The larger the electromechanical coupling coefficient, the higher the conversion efficiency. It is reflected in the frequency bandwidth between the resonant frequency and the anti-resonant frequency in the actual performance of the resonator. The electromechanical coupling coefficient is defined as the efficiency of energy conversion, but it is difficult to directly apply the definition of energy conversion to calculate the electromechanical coupling coefficient in actual calculations. Therefore, several calculation formulas are often used in the actual calculation of the electromechanical coupling coefficient. The calculation form used in the present invention is: where k t is the electromechanical coupling coefficient, f r is the resonant frequency, f a is the anti-resonance frequency.

[0044] Embodiment 1

[0045] This embodiment provides a lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure, such as Figure 1 As shown, it includes an upper surface electrode 1, a lithium niobate acoustic superlattice 2 and a lower surface electrode 3 stacked in sequence from top to bottom, wherein the lithium niobate acoustic superlattice 2 includes alternating positive domain regions 21 and negative domain regions 22, the piezoelectric coefficient of the positive domain region is positive, and the piezoelectric coefficient of the negative domain region is negative, both the positive domain region and the negative domain region are inclined domains, and the inclination angle θ=60°, that is, a ZX-cut lithium niobate with a cut type of 60°.

[0046] The upper surface electrode 1 and the lower surface electrode 3 are both flat aluminum electrodes with a single layer thickness h1 of 200 nm, the thickness H of the lithium niobate acoustic superlattice is 5 μm, and the distribution period T of the ferroelectric domains of the lithium niobate acoustic superlattice is 8 μm.

[0047] Embodiment 2

[0048] This embodiment provides another lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure, which is different from the first embodiment in that the tilt angle θ of the positive domain region and the negative domain region is 30°, and other parameters are the same.

[0049] It can be understood that in other embodiments, the upper surface electrode and the lower surface electrode can also be multilayered metal, specifically at least one of Au, Pt, Cr, W, Mo, Ni, Fe, and Ti. The tilt angle θ can be set to any value in (0°, 90°)∪(90°, 180°).

[0050] Embodiment 3

[0051] This embodiment provides a design method for a lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure, specifically comprising:

[0052] Step (1), obtaining simulation parameters of a lithium niobate acoustic superlattice body acoustic wave resonator device that can achieve target performance, including physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device and the ferroelectric domain distribution period T of the lithium niobate acoustic superlattice; the physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device include upper surface electrode material m1, thickness h1 and shape s1, lower surface electrode material m2, thickness h2 and shape s2, tilt angle θ, lithium niobate acoustic superlattice thickness H; the lithium niobate acoustic superlattice can convert radio frequency signals into sound waves under the action of a periodic electric field of a specific frequency f, the exciting sound wave frequency is the same as the radio frequency signal frequency, and the relationship between its resonant frequency f and the period T is: f=v / T, wherein v is the corresponding wave velocity of the resonant mode in the lithium niobate acoustic superlattice.

[0053] This step specifically includes:

[0054] Step (1.1), setting preliminary simulation parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device, including the physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device and the tilt angle θ of the lithium niobate acoustic superlattice and the ferroelectric domain distribution period T;

[0055] Step (1.2), using the Euler angle transformation (α, β, γ) of the ZXZ rotation method to transform the material coordinate system of the Z-cut lithium niobate into the material coordinate system of the ZX-cut lithium niobate with an angle of θ. The Euler angle of the positive domain region transformation is (0°, θ+90°, 0°), and the Euler angle of the negative domain region transformation is (0°, θ-90°, 0°).

[0056] Step (1.3), establishing a geometric model of a lithium niobate acoustic superlattice body acoustic wave resonator device in a simulation software, setting the physical size parameters of the geometric model to the physical size parameters of the simulation parameters, setting the ferroelectric domain distribution period of the lithium niobate acoustic superlattice in the geometric model to T in the simulation parameters, and meshing the geometric model;

[0057] Step (1.4), perform frequency domain calculation based on the meshed geometric model, draw the admittance curve and vibration mode diagram according to the frequency domain calculation results, and calculate the electrical coupling coefficient and resonant frequency;

[0058] Step (1.5), determine whether the electromechanical coupling coefficient is higher than the threshold, whether the resonant frequency is within the resonant frequency range, and whether the parasitic mode is suppressed; if all the judgment results are yes, output the simulation parameters at this time; otherwise, readjust the simulation parameters and return to step (1.2);

[0059] Step (2), according to the simulation parameters of step (1), selecting a lithium niobate substrate of a corresponding cut type, specifically a ZX cut type with an angle of θ;

[0060] Step (3), calculate the coercive field of lithium niobate according to the tilt angle θ:

[0061] E c (θ) = E c (90°) / cos(θ-90°)

[0062] In the formula, E c (θ) Coercive field of lithium niobate when the tilt angle is θ, E c (90°) represents the coercive field of lithium niobate when the tilt angle is 90°;

[0063] Step (4), according to the ferroelectric domain distribution period T, the thickness H of lithium niobate in the simulation parameters and the coercive field E of lithium niobate when the tilt angle is θ c (θ) selecting a polarization method for making the lithium niobate substrate into a lithium niobate acoustic superlattice;

[0064] Step (5), selecting electrode materials that meet the simulation parameters on the upper and lower surfaces of the lithium niobate acoustic superlattice to form an upper surface electrode and a lower surface electrode respectively.

[0065] Comparative Example

[0066] This comparative example provides another lithium niobate acoustic superlattice body acoustic wave resonator device, which is different from the first embodiment in that the tilt angle θ of the positive domain region and the negative domain region is 90°, that is, a traditional lithium niobate acoustic superlattice with a non-tilted domain structure, and the other parameters are the same.

[0067] The following simulation experiments are conducted on Example 1, Example 2 and the comparative example under different resonance modes. Figure 2 As shown, when θ=90°, the lithium niobate acoustic superlattice has no A0 modal working resonance mode, and when θ=60°, the lithium niobate has an A0 modal Lamb wave working resonance mode, with a resonant frequency of 397 MHz, an anti-resonant frequency of 399 MHz, and an electromechanical coupling coefficient of 1.2%. Figure 3 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=90° and the resonance frequency is 397MHz; Figure 4 This is the vibration mode diagram of the lithium niobate acoustic superlattice when θ = 60° and the resonant frequency is 397MHz. Figure 5 As shown in the figure, when θ=90°, the resonant frequency of the S0 mode Lamb wave working resonant mode of the lithium niobate acoustic superlattice is 610MHz, the anti-resonant frequency is 614MHz, and the electromechanical coupling coefficient is 1.6%; when θ=60°, the resonant frequency of the S0 mode Lamb wave working resonant mode of the lithium niobate acoustic superlattice is 586MHz, the anti-resonant frequency is 621MHz, and the electromechanical coupling coefficient is 15.1%. While the resonance effect is improved, the electromechanical coupling coefficient is significantly improved. Figure 6 is the vibration mode diagram of lithium niobate acoustic superlattice when θ=90° and the resonant frequency is 610MHz. Figure 7 It is the vibration mode diagram of lithium niobate acoustic superlattice when θ=60° and the resonant frequency is 586MHz. As shown in Figure 8, when θ=90°, the resonant frequency of the S2 mode Lamb wave working resonant mode of the lithium niobate acoustic superlattice is 1186MHz, the anti-resonant frequency is 1188MHz, and the electromechanical coupling coefficient is 0.4%. When θ=60°, the resonant frequency of the S2 mode Lamb wave working resonant mode of the lithium niobate acoustic superlattice is 1201MHz, the anti-resonant frequency is 1202MHz, and the electromechanical coupling coefficient is 0.2%. Fig. 9 is the vibration mode diagram of lithium niobate acoustic superlattice when θ=90° and the resonance frequency is 1186MHz; Fig.10 This is the vibration mode diagram of the lithium niobate acoustic superlattice when θ=60° and the resonance frequency is 1201MHz. Here, the 60° tilt angle tilt domain structure lithium niobate acoustic superlattice has a good suppression effect on the resonance mode. Fig.11 As shown, when θ=30°, the resonant frequency of the S2 mode Lamb wave working resonant mode of the lithium niobate acoustic superlattice is 1128 MHz, the anti-resonant frequency is 1178 MHz, and the electromechanical coupling coefficient is 11.7%. Fig.12 This is the vibration mode diagram of lithium niobate acoustic superlattice when θ=30° and the resonant frequency is 1128MHz.

[0068] Among them, the lithium niobate acoustic superlattice body acoustic wave resonator device when θ=60° and θ=120° is a symmetrical structure, the data is consistent, and no further description is given. The lithium niobate acoustic superlattice body acoustic wave resonator device when θ=30° and θ=150° is a symmetrical structure, the data is consistent, and no further description is given.

[0069] It should be understood that the above embodiments and descriptions only describe the principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention may also have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure, characterized in that: It includes an upper surface electrode, a lithium niobate acoustic superlattice and a lower surface electrode stacked in sequence from top to bottom, wherein the lithium niobate acoustic superlattice includes alternating positive domain regions and negative domain regions, the piezoelectric coefficient of the positive domain region is positive, the piezoelectric coefficient of the negative domain region is negative, and both the positive domain region and the negative domain region are inclined domains.

2. The lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure according to claim 1, characterized in that: The upper surface electrode is a single-layer metal or a multi-layer metal.

3. The lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure according to claim 1, characterized in that: The upper surface electrode is at least one of Al, Au, Pt, Cr, W, Mo, Ni, Fe, and Ti.

4. The lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure according to claim 1, characterized in that: The lower surface electrode is a single-layer metal or a multi-layer metal.

5. The lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure according to claim 1, characterized in that: The lower surface electrode is at least one of Al, Au, Pt, Cr, W, Mo, Ni, Fe, and Ti.

6. The lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure according to claim 1, characterized in that: The inclination angles θ∈(0°, 90°)∪(90°, 180°) between the positive domain region and the negative domain region and the electrode surface.

7. A design method for a lithium niobate acoustic superlattice body acoustic wave resonator device based on a tilted domain structure according to claim 1, characterized in that: include: Step (1), obtaining simulation parameters of a lithium niobate acoustic superlattice body acoustic wave resonator device that can achieve target performance, including physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device and the tilt angle θ and ferroelectric domain distribution period T of the lithium niobate acoustic superlattice; Step (2), selecting a lithium niobate substrate of a corresponding cut type according to the simulation parameters of step (1); Step (3), calculate the coercive field of lithium niobate according to the tilt angle θ: E c (θ)=E c (90°) / cos(θ-90°) In the formula, E c (θ) Coercive field of lithium niobate when the tilt angle is θ, E c (90°) represents the coercive field of lithium niobate when the tilt angle is 90°; Step (4), according to the ferroelectric domain distribution period T, the thickness H of lithium niobate in the simulation parameters and the coercive field E of lithium niobate when the tilt angle is θ c (θ) selecting a polarization method for making the lithium niobate substrate into a lithium niobate acoustic superlattice; Step (5), selecting electrode materials that meet the simulation parameters on the upper and lower surfaces of the lithium niobate acoustic superlattice to form upper surface electrodes and lower surface electrodes respectively.

8. The design method of the lithium niobate acoustic superlattice body acoustic wave resonator device based on the tilted domain structure according to claim 7 is characterized in that: The physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device include upper surface electrode material m1, thickness h1 and shape s1, lower surface electrode material m2, thickness h2 and shape s2, tilt angle θ, ferroelectric domain distribution period T and lithium niobate acoustic superlattice thickness H.

9. The design method of the lithium niobate acoustic superlattice body acoustic wave resonator device based on the tilted domain structure according to claim 7, characterized in that: Step (1) specifically includes: Step (1.1), setting preliminary simulation parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device, including physical size parameters of the lithium niobate acoustic superlattice body acoustic wave resonator device and the ferroelectric domain distribution period T of the lithium niobate acoustic superlattice; Step (1.2), using the Euler angle transformation (α, β, γ) of the ZXZ rotation method to transform the material coordinate system of the Z-cut lithium niobate into the material coordinate system of the ZX-cut lithium niobate with an angle of θ, wherein the Euler angle of the positive domain region transformation is (0°, θ+90°, 0°), and the Euler angle of the negative domain region transformation is (0°, θ-90°, 0°); Step (1.3), establishing a geometric model of a lithium niobate acoustic superlattice body acoustic wave resonator device in a simulation software, setting the physical size parameters of the geometric model to the physical size parameters of the simulation parameters, setting the ferroelectric domain distribution period of the lithium niobate acoustic superlattice in the geometric model to T in the simulation parameters, and meshing the geometric model; Step (1.4), perform frequency domain calculation based on the meshed geometric model, draw the admittance curve and vibration mode diagram according to the frequency domain calculation results, and calculate the electrical coupling coefficient and resonant frequency; Step (1.5), determine whether the electromechanical coupling coefficient is higher than the threshold, whether the resonant frequency is within the resonant frequency range, and whether the parasitic mode is suppressed; if all the judgment results are yes, output the simulation parameters at this time; otherwise, readjust the simulation parameters and return to execute step (1.2).

10. The design method of the lithium niobate acoustic superlattice body acoustic wave resonator device based on the tilted domain structure according to claim 7, characterized in that: The cutting shape of the lithium niobate substrate in step (2) is specifically a ZX cutting shape with an angle of θ.

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