A high-frequency acoustic wave resonator and a method for preparing the same

Abstract

This application relates to the technical field of resonators, and particularly to a high-frequency acoustic wave resonator and a preparation method thereof. The high-frequency acoustic wave resonator of this application includes a first support substrate, a reflective layer, a piezoelectric film, and an electrode that are sequentially stacked. Among them, the reflective layer is formed by ion implantation modification of a base material body; it includes at least one low-sound velocity reflective layer and one high-sound velocity reflective layer that are stacked along the thickness direction of the first support substrate. The reflective layer can reflect the energy of the high-sound velocity acoustic wave layer by layer, confine the energy of the high-sound velocity acoustic wave inside the piezoelectric layer and the reflective layer, and prevent the energy of the high-sound velocity acoustic wave from leaking to the first support substrate and causing loss. It realizes the effective excitation of high-sound velocity and large electromechanical coupling coefficient acoustic wave modes, and manufactures a high-frequency and large-bandwidth acoustic wave resonator.

Description

Technical Field

[0001] The present application relates to the technical field of resonators, and particularly to a high-frequency acoustic wave resonator and a preparation method thereof. Background Art

[0002] With the rapid development of modern wireless communication technologies, various communication frequency spectrums have emerged to meet the growing communication demands. The signal frequency bands are continuously increasing, the operating frequencies are rising, and the operating bandwidths are expanding. This poses more stringent requirements on the radio frequency (RF) front-end modules in mobile communication devices, and the RF front-end requires higher performance and better reliability. As a main device in the RF front-end, the filter plays an important role in the signal processing process. As the number of signal frequency spectrums that mobile terminals such as mobile phones and tablets need to support continues to increase, a corresponding filter is required for each spectrum to process the signal, and the number of filters required in mobile terminals is also continuously rising.

[0003] One prominent challenge currently is the lack of miniaturized high-frequency and broadband acoustic wave filters in the C-band (4 - 8 GHz). For example, to implement 5G technology, it is necessary to access a larger physical bandwidth to expand the data capacity, which poses higher requirements on the performance of acoustic wave filters. An acoustic wave filter includes multiple acoustic wave resonators, and acoustic wave resonators generally include surface acoustic wave (SAW) resonators and bulk acoustic wave (BAW) resonators. In related technologies, when the frequency to be achieved is relatively high, for SAW resonators, the design of the substrate structure sound velocity, the target acoustic wave sound velocity, and the patterned electrode line width need to be comprehensively considered, and both the preparation process and the device stability face severe challenges; for BAW resonators, the frequency can be increased by reducing the thickness of the piezoelectric film, but its bandwidth is limited. To prevent the leakage of acoustic wave energy, the support substrate of the BAW resonator is usually suspended, which has problems of poor structural stability and poor heat dissipation. Therefore, it is urgent to solve the problem that acoustic wave filters cannot have both high frequency, large bandwidth, high mechanical stability, and excellent heat dissipation. Summary of the Invention

[0004] In view of the above problems in the prior art, the present application provides a high-frequency acoustic wave resonator and a preparation method thereof, which can solve the problem that acoustic wave filters cannot have both high frequency, large bandwidth, high mechanical stability, and excellent heat dissipation. The specific technical solutions are as follows:

[0005] On the one hand, the present application provides a high-frequency acoustic wave resonator, including:

[0006] A first support substrate;

[0007] A reflective layer located on one surface of the first support substrate, the reflective layer is formed by ion implantation modification of a base material body; at least including a low sound velocity reflective layer and a high sound velocity reflective layer stacked along the thickness direction of the first support substrate;

[0008] A piezoelectric film located on the surface of the reflective layer facing away from the first support substrate, which is a heterogeneous material with the first support substrate and also a heterogeneous material with the reflective layer. The acoustic impedances of the low acoustic velocity reflective layer, the piezoelectric film, and the base material body increase in sequence, and the acoustic impedance of the high acoustic velocity reflective layer is greater than that of the piezoelectric film;

[0009] An electrode located on the surface of the piezoelectric film facing away from the reflective layer.

[0010] In a possible implementation, the reflective layer satisfies at least one of the following characteristics:

[0011] The low acoustic velocity reflective layer includes 2 - 5 layers;

[0012] The high acoustic velocity reflective layer includes 2 - 5 layers;

[0013] The modification coefficient of the low acoustic velocity reflective layer is 0.01 - 0.6;

[0014] The modification coefficient of the high acoustic velocity reflective layer is 0.7 - 3, and the modification coefficient is the ratio of the elastic coefficient of the base material body after modification to the elastic coefficient before modification.

[0015] In a possible implementation, the high - frequency acoustic wave resonator satisfies at least one of the following characteristics:

[0016] The ratio of the slow shear wave acoustic velocity of the base material body to the acoustic velocity of the target acoustic wave propagating in the piezoelectric layer is not less than 0.4;

[0017] The material of the first support substrate includes one or more of silicon carbide, silicon, sapphire, quartz, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, diamond, diamond - like, boron carbide, boron nitride, and zirconia;

[0018] The material of the base material body includes one or more of silicon carbide, silicon, sapphire, quartz, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, diamond, diamond - like, boron carbide, boron nitride, and zirconia;

[0019] The material of the base material body includes one or more of silicon oxide, fluorine - containing silicon oxide, silicon oxynitride, polysilicon, tantalum pentoxide, and tellurium dioxide;

[0020] The material of the piezoelectric layer includes one or more of lithium niobate, potassium niobate, lithium tantalate, aluminum nitride, quartz, and zinc oxide;

[0021] The electrode is a patterned electrode, and the period of the patterned electrode is λ;

[0022] The electrode is a full - surface electrode.

[0023] In a possible implementation, the thickness of the reflection layer satisfies at least one of the following characteristics:

[0024] The thickness of one layer of the low acoustic velocity reflection layer is 0.1 - 0.4λ;

[0025] The thickness of one layer of the high acoustic velocity reflection layer is 0.1 - 0.4λ.

[0026] In a possible implementation, the base material body and the first support substrate are made of the same material.

[0027] In a possible implementation, a second support substrate is further provided between the reflection layer and the piezoelectric film, and the second support substrate satisfies at least one of the following characteristics:

[0028] The second support substrate and the first support substrate are made of the same material;

[0029] The thickness of the second support substrate does not exceed 0.4λ.

[0030] In a possible implementation, a first dielectric layer is further provided between the reflection layer and the piezoelectric film, and the first dielectric layer satisfies at least one of the following characteristics:

[0031] The material of the first dielectric layer includes one or more of silicon oxide, fluorine-containing silicon oxide, silicon oxynitride, polysilicon, aluminum nitride, tantalum pentoxide, tellurium dioxide;

[0032] The thickness of the first dielectric layer is 0.1 - 1λ.

[0033] In a possible implementation, the base material body and the first support substrate are heterogeneous materials, and the high-frequency acoustic wave resonator satisfies at least one of the following characteristics:

[0034] A second dielectric layer is further provided between the piezoelectric film and the reflection layer;

[0035] The thickness of the second dielectric layer does not exceed 0.4λ.

[0036] On the other hand, the present application provides a method for manufacturing a high-frequency acoustic wave resonator, including the following steps:

[0037] Provide a first support substrate and a base material body arranged in a stacked manner;

[0038] Modify the base material body by ion implantation to form a reflection layer on one side surface of the first support substrate; the reflection layer is formed by ion implantation modification of the base material body; at least includes a layer of low acoustic velocity reflection layer and a layer of high acoustic velocity reflection layer arranged in a stacked manner along the thickness direction of the first support substrate;

[0039] A piezoelectric film is formed on the surface of the reflection layer facing away from the first support substrate. The piezoelectric film is a heterogeneous material with respect to the first support substrate and also with respect to the reflection layer. The acoustic impedance of the low acoustic velocity reflection layer, the piezoelectric film, and the base material body increases in sequence, and the acoustic impedance of the high acoustic velocity reflection layer is greater than that of the piezoelectric film.

[0040] An electrode is formed on the surface of the piezoelectric film facing away from the reflection layer to obtain the high-frequency acoustic wave resonator.

[0041] In a possible implementation manner, before the ion implantation step, a buffer layer is further provided on the surface of the base material body facing away from the first support substrate, and before the step of forming the piezoelectric film, the buffer layer is removed.

[0042] Based on the above technical solution, the present application has the following beneficial effects:

[0043] The technical solution of the present application provides a high-frequency acoustic wave resonator and a preparation method thereof. The high-frequency acoustic wave resonator includes a first support substrate, a reflection layer, a piezoelectric film, and an electrode that are sequentially stacked. The reflection layer is formed by ion implantation modification of the base material body, and the reflection layer includes at least one layer of low acoustic velocity reflection layer and one layer of high acoustic velocity reflection layer that are alternately arranged. The acoustic impedance of the low acoustic velocity reflection layer, the piezoelectric film, and the base material body increases in sequence, and the acoustic impedance of the high acoustic velocity reflection layer is greater than that of the piezoelectric film. By providing a reflection layer between the first support substrate and the piezoelectric layer, and when the acoustic impedances of the low / high acoustic velocity reflection layer, the piezoelectric film, and the base material body meet the above requirements, the reflection layer can reflect the energy of the high acoustic velocity acoustic wave layer by layer, confine the energy of the high acoustic velocity acoustic wave inside the piezoelectric layer and the reflection layer, and prevent the energy of the high acoustic velocity acoustic wave from leaking to the first support substrate and causing loss. It realizes the effective excitation of the high acoustic velocity and large electromechanical coupling coefficient acoustic wave modes, and manufactures a high-frequency and large-bandwidth acoustic wave resonator. In addition, in the present application, the reflection layer is obtained by using ion implantation to modify the base material body, without the need to suspend the structure of the first support substrate, without etching the piezoelectric film, retaining the structural integrity of the piezoelectric film and the first support substrate, and the piezoelectric film and the first support substrate are heterogeneous materials, which helps to dissipate heat and compensate and improve the frequency temperature coefficient. Therefore, the filter made of the acoustic wave resonator of the present application has both high frequency, large bandwidth, high mechanical stability, and excellent heat dissipation. Description of the Drawings

[0044] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those of ordinary skill in the art can also obtain other drawings according to these drawings without creative efforts.

[0045] Figure 1 Schematic diagrams of the high-frequency acoustic wave resonators in Embodiments 1, 3, and 4;

[0046] Figure 2 Schematic diagrams of the high-frequency acoustic wave resonators in Embodiments 2 and 5;

[0047] Figure 3 Schematic diagram of the high-frequency acoustic wave resonator in Embodiment 6;

[0048] Figure 4 Schematic diagram of the high-frequency acoustic wave resonator in Embodiment 7;

[0049] Figure 5 Schematic diagrams of the high-frequency acoustic wave resonators in Comparative Examples 1, 3, and 4;

[0050] Figure 6 Schematic diagram of the high-frequency acoustic wave resonator in Comparative Example 2;

[0051] Figure 7 In a, it is the admittance response curve graph of the high-frequency acoustic wave resonator in Embodiment 1;

[0052] Figure 7 In b, it is the vibration mode graph of the resonance frequency point of the high-frequency acoustic wave resonator in Embodiment 1;

[0053] Figure 8 Admittance response curve graphs of the high-frequency acoustic wave resonators in Embodiments 2 and 5;

[0054] Figure 9 Admittance response curve graphs of the high-frequency acoustic wave resonators in Embodiments 3 and 4;

[0055] Figure 10 Admittance response curve graph of the high-frequency acoustic wave resonator in Embodiment 6;

[0056] Figure 11 Admittance response curve graph of the high-frequency acoustic wave resonator in Embodiment 7;

[0057] Figure 12 Admittance response curve graphs of the high-frequency acoustic wave resonators in Comparative Examples 1, 2, 3, and 4;

[0058] Figure 13 Admittance response curve graphs of the high-frequency acoustic wave resonators corresponding to different numbers of reflection layers;

[0059] Figure 14 Admittance response curve graphs of the high-frequency acoustic wave resonators corresponding to different modification coefficients of the high-velocity sound reflection layer;

[0060] Figure 15 Schematic diagram of the high-frequency acoustic wave resonator when the electrode is a planar electrode.

[0061] Reference numerals: 1, first support substrate; 2, reflective layer; 3, piezoelectric film; 4, interdigital electrode; 5, second support substrate; 6, first dielectric layer; 7, second dielectric layer; 8, surface electrode; 9, third dielectric layer. Detailed implementation manners

[0062] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0063] For the terms defined below, unless a different definition is given elsewhere in the claims or in this specification, these definitions shall apply. All numerical values, whether or not explicitly indicated, are hereby defined as being modified by the term "about". The term "about" generally refers to a numerical range that those of ordinary skill in the art would consider equivalent to the stated value to produce substantially the same properties, functions, results, etc. A numerical range indicated by a low value and a high value is defined to include all the numerical values included in the numerical range and all the sub-ranges included in the numerical range.

[0064] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0065] Acoustic resonators include surface acoustic wave resonators and bulk acoustic wave resonators. To increase the operating frequency of acoustic resonators, surface acoustic wave resonators can be used by shortening the line width of their interdigital electrodes or increasing the target sound velocity. However, shortening the line width of the interdigital electrodes faces high process difficulty, and an overly short line width of the interdigital electrodes is likely to cause problems such as poor temperature stability and power capacity performance of the resonator, and both the manufacturing process and performance stability face challenges; while increasing the target sound velocity also faces the problem that high-speed acoustic wave energy is likely to leak to the substrate. In related technologies, the method of suspending and supporting the substrate or setting a Bragg reflector layer between the piezoelectric film and the supporting substrate is adopted, and both of these methods have drawbacks. The method of suspending and supporting the substrate will reduce the mechanical stability of the resonator, and the metal material serving as the high-speed layer in the Bragg reflector layer will form a parasitic capacitance with the metal electrode on the surface layer of the resonator, deteriorating the performance of the resonator. To increase the operating frequency of acoustic resonators, bulk acoustic wave resonators usually adopt the method of reducing the thickness of the piezoelectric film and increasing the target sound velocity of the acoustic wave, but its bandwidth is limited, and the problem of high-speed acoustic wave energy leaking to the supporting substrate also needs to be considered. In view of this, to solve at least one of the above problems, the present application provides a high-frequency acoustic resonator and a manufacturing method thereof.

[0066] The following will introduce the high-frequency acoustic resonator of the present application in conjunction with Figures 1-15 , including:

[0067] A first supporting substrate;

[0068] A reflector layer located on one side surface of the first supporting substrate, and the reflector layer is formed by ion implantation modification of the base material body; at least includes a low-speed reflector layer and a high-speed reflector layer stacked along the thickness direction of the first supporting substrate;

[0069] A piezoelectric film located on the surface of the reflector layer facing away from the first supporting substrate, which is a heterogeneous material with the first supporting substrate and also a heterogeneous material with the reflector layer. The acoustic impedance of the low-speed reflector layer, the piezoelectric film, and the base material body increases in sequence, and the acoustic impedance of the high-speed reflector layer is greater than that of the piezoelectric film;

[0070] An electrode located on the surface of the piezoelectric film facing away from the reflector layer.

[0071] Based on the above solution, the present application modifies the base material body by ion implantation to form a reflective layer, and disposes the reflective layer between the first support substrate and the piezoelectric film, reflecting the energy of the high acoustic velocity sound wave layer by layer, confining the energy of the high acoustic velocity sound wave inside the piezoelectric layer and the reflective layer, and preventing the energy of the high acoustic velocity sound wave from leaking to the first support substrate and causing loss. The effective excitation of the acoustic wave modes with high acoustic velocity and large electromechanical coupling coefficient is realized, and an acoustic wave resonator with high frequency and large bandwidth is fabricated. In addition, the piezoelectric film and the first support substrate of the present application are heterogeneous materials, which helps to dissipate heat and compensate and improve the frequency temperature coefficient. The piezoelectric material itself is a material with very low thermal conductivity. Using a piezoelectric film + heterogeneous substrate can improve the heat dissipation efficiency of the device, accelerate heat dissipation and reduce the steady-state operating temperature of the device, thereby reducing the problem of frequency drift of the device caused by the increase in operating temperature. If a substrate made of the same material as the piezoelectric film is used, it will result in a relatively low level of thermal conductivity of the acoustic wave resonator, and there will be problems such as difficult heat dissipation and poor device operating stability.

[0072] In some embodiments, the low acoustic velocity reflective layer includes 2 - 5 layers, and the high acoustic velocity reflective layer includes 2 - 5 layers. In this way, when the number of layers of the low acoustic velocity reflective layer and the high acoustic velocity reflective layer is within the above range, the reflection effect on the high acoustic velocity sound wave is better, and the energy of the high acoustic velocity sound wave can be better confined inside the piezoelectric layer and the reflective layer, ensuring that the energy does not leak into the substrate and cause loss. When the number of layers of the low / high acoustic velocity reflective layer is less than 2 layers, the reflection effect is not good. When the number of layers of the low / high acoustic velocity reflective layer is more than 5 layers, there is a problem of complex manufacturing process.

[0073] Specifically, the modification coefficient of the low acoustic velocity reflective layer is 0.01 - 0.6, and the modification coefficient of the high acoustic velocity reflective layer is 0.7 - 3; the modification coefficient is defined as the ratio of the elastic coefficient of the base material body after modification to the elastic coefficient before modification; it can be understood that a modification coefficient greater than 1 makes the elastic coefficient of the base material body larger and the acoustic impedance larger, and a modification coefficient less than 1 makes the elastic coefficient of the base material body smaller and the acoustic impedance lower; it can be understood that the acoustic impedance of the low acoustic velocity reflective layer is lower than that of the base material body, and the acoustic impedance of the high acoustic velocity reflective layer can be lower than, equal to, or higher than that of the base material body. The acoustic impedance of the high acoustic velocity reflective layer being equal to that of the base material body can be understood as using the base material body itself as the high acoustic velocity reflective layer, without the need to modify the base material body, thereby reducing the implantation step and the manufacturing process. The acoustic impedance of the high acoustic velocity reflective layer is higher than that of the piezoelectric film, and the acoustic impedance of the low acoustic velocity reflective layer is lower than that of the piezoelectric film. The low acoustic velocity reflective layer and the high acoustic velocity reflective layer are stacked in a butt joint manner, and the greater the difference in acoustic impedance between the two, the better the confinement effect on the energy of the high acoustic velocity sound wave.

[0074] Specifically, when the modification coefficient ranges from less than 1, the types of ions implanted are one or more of hydrogen, helium, nitrogen, oxygen, carbon, silicon, boron, phosphorus, etc., and co-implantation of two or more ions is allowed; the implantation dose ranges from 1e14 / cm 2 to 1e17 / cm 2 ; the implantation energy ranges from 25 to 200 keV; when the modification coefficient ranges from greater than 1, the types of ions implanted are one or more of chromium ions, sodium ions, magnesium ions, aluminum ions, calcium ions, scandium ions, lithium ions, titanium ions, molybdenum ions, cobalt ions, nickel ions, etc., and the implantation dose ranges from 1e14 / cm 2 to 1e17 / cm 2 ; the implantation energy ranges from 25 to 200 keV. It can be understood that the implantation energy of ion implantation determines the depth where the modified layer is located, the implantation dose of ion implantation determines the thickness of the modified layer, and the energy, dose, and type of ions of ion implantation jointly determine the modification coefficient of the modified layer.

[0075] In some embodiments, the ratio of the slow shear wave sound velocity of the base material body to the sound velocity of the target sound wave propagating in the piezoelectric layer is not less than 0.4; it can be understood that the slow shear wave sound velocity of the base material body refers to the sound velocity of the slowest shear wave that can propagate in the base material body; for example, the slow shear wave sound velocity of silicon is 5846 m / s, the slow shear wave sound velocity of sapphire is 6045 m / s, and the slow shear wave sound velocity of single crystal 3c - silicon carbide is 8501 m / s; the sound velocity of the target sound wave propagating in the piezoelectric layer refers to the sound velocity of the target working sound wave excited by an electrical signal under the working state of the high - frequency acoustic wave resonator. The types of target sound waves that the high - frequency acoustic wave resonator of the present application can excite include, but are not limited to, first - order and / or higher - order (n, n≥1) horizontal shear waves, vertical shear waves, longitudinal waves, antisymmetric Lamb wave modes, symmetric Lamb wave modes, etc.; the types of acoustic wave modes include, but are not limited to, high - sound - velocity acoustic wave modes such as thickness longitudinal waves and thickness shear waves. For example, the sound velocity of the first - order symmetric Lamb wave can be as high as more than 10000 m / s; the sound velocity of the first - order antisymmetric Lamb wave can be as high as more than 13000 m / s; the sound velocity of the third - order antisymmetric Lamb wave can be as high as more than 20000 m / s.

[0076] Thus, in the present application, by providing alternately stacked low-velocity reflection layers and high-velocity reflection layers, the energy of high-velocity acoustic waves can be better confined within the piezoelectric layer and the reflection layers, ensuring that the energy does not leak into the substrate and cause losses. Without the reflection layer structure, it is necessary to find a base material body with a slow shear wave velocity higher than the velocity of the target acoustic wave as the supporting substrate. However, the base material body that meets the above requirements has a high cost and is difficult to process, and it is very difficult to obtain. By providing the reflection layer structure in the present application, it is only necessary to ensure that the ratio of the slow shear wave velocity of the base material body to the velocity of the target acoustic wave propagating in the piezoelectric layer is not less than 0.4, so as to effectively confine the energy of the high-velocity acoustic wave. The base material body that meets this condition has a lower cost and a lower processing difficulty.

[0077] In some embodiments, the high-frequency acoustic wave resonator satisfies at least one of the following characteristics: the material of the first supporting substrate includes one or more of silicon carbide, silicon, sapphire, quartz, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, diamond, diamond-like, boron carbide, boron nitride, and zirconia; the material of the piezoelectric layer includes one or more of lithium niobate, potassium niobate, lithium tantalate, aluminum nitride, quartz, and zinc oxide; the electrode is a patterned electrode, and the period of the patterned electrode is λ; the electrode is a full-surface electrode.

[0078] It can be understood that the electrode can be a patterned electrode or a full-surface electrode. When the electrode is a patterned electrode, the period of the patterned electrode is λ, where λ = 2×(finger electrode line width + finger electrode pitch). The patterned electrode includes any one of finger electrodes, circular finger electrodes, arc-shaped finger electrodes, or finger electrodes with other patterns. At this time, the excited target acoustic waves can be acoustic wave modes such as surface acoustic waves and Lamb waves; when the electrode is a surface electrode, this surface electrode is defined as the upper electrode, and a lower electrode is provided on the surface of the piezoelectric film facing away from the upper electrode. The lower electrode is also a surface electrode. At this time, the excited target acoustic waves are acoustic wave modes such as bulk acoustic waves.

[0079] Specifically, the thickness of one layer of the low-velocity reflection layer is 0.1 - 0.4λ, and the thickness of one layer of the high-velocity reflection layer is 0.1 - 0.4λ. Further, when the number of low-velocity reflection layers and high-velocity reflection layers is greater than or equal to 2, the modification coefficients of each layer of low-velocity reflection layers can be all the same or all different. When the modification coefficients are all the same, their thicknesses can be the same or slightly different, with the difference not exceeding λ / 10; when the modification coefficients are different from each other, their thicknesses are different, forming a gradually changing group of low-velocity reflection layers; the same applies to the thickness setting of the high-velocity reflection layers. By controlling the thickness of each layer of the reflection layer within the above range, the reflection layer has a better reflection effect on the energy of the high-velocity acoustic wave.

[0080] In some embodiments, the base material body and the first support substrate are made of the same material. The material of the base material body includes one or more of silicon carbide, silicon, sapphire, quartz, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, diamond, diamond-like carbon, boron carbide, boron nitride, and zirconia. Understandably, the reflective layer is formed by ion implantation modification of the first support substrate. Ions can be implanted starting from the surface of the first support substrate close to the piezoelectric film, or a layer of the support substrate that is not implanted can be retained. This non-implanted layer of the support substrate is defined as the second support substrate, and then a reflective layer is formed on the side of the second support substrate close to the first support substrate. The second support substrate and the first support substrate are made of the same material. Further, the thickness of the second support substrate does not exceed 0.4λ.

[0081] Preferably, a first dielectric layer is further provided between the reflective layer and the piezoelectric film. The first dielectric layer satisfies at least one of the following characteristics: the material of the first dielectric layer includes one or more of silicon oxide, fluorine-containing silicon oxide, silicon oxynitride, polysilicon, aluminum nitride, tantalum pentoxide, and tellurium dioxide; the thickness of the first dielectric layer is 0.1 - 1λ. Understandably, the piezoelectric film, the first dielectric layer, and the first support substrate are made of heterogeneous materials. Thus, selecting the above materials as the first dielectric layer can further compensate for heat dissipation or compensate for the frequency temperature coefficient, and further improve the frequency temperature stability of the high-frequency acoustic wave resonator.

[0082] In some embodiments, the base material body and the first support substrate are made of heterogeneous materials. The material of the base material body includes one or more of silicon, silicon carbide, sapphire, diamond, diamond-like carbon, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, boron carbide, boron nitride, quartz, zirconia, silicon oxide, fluorine-containing silicon oxide, silicon oxynitride, polysilicon, aluminum nitride, tantalum pentoxide, and tellurium dioxide. Understandably, the base material body is first formed on the surface of the first support substrate close to the piezoelectric film, and then the base material body is implanted and modified to obtain the reflective layer.

[0083] In some embodiments, the base material body and the first support substrate are made of heterogeneous materials, and ions are implanted starting from the surface of the base material body close to the piezoelectric film to form the reflective layer. Further, a second dielectric layer is further provided between the reflective layer and the piezoelectric film. The second dielectric layer can be made of the same material as the base material body or can be made of heterogeneous materials with the base material body. Further, the thickness of the second dielectric layer does not exceed 0.4λ. Thus, the second dielectric layer can further compensate for heat dissipation or compensate for the frequency temperature coefficient, and further improve the frequency temperature stability of the high-frequency acoustic wave resonator.

[0084] In some embodiments, the surface of the high-frequency acoustic wave resonator may further include a temperature compensation layer or an electrode insulating layer.

[0085] On the other hand, an embodiment of the present application also provides a method for preparing a high-frequency acoustic resonator, which may include the following steps S1-S4:

[0086] S1: Provide a first support substrate and a base material body arranged in a stacked manner;

[0087] In some embodiments, the base material body may be the first support substrate or a material body made of a material different from that of the first support substrate. When the materials of the base material body and the first support substrate are different, it can be formed on the surface of the first support substrate by at least techniques such as bonding and peeling, bonding and grinding, physical vapor deposition, chemical vapor deposition, magnetron sputtering deposition, and thermal oxidation deposition.

[0088] S2: Modify the base material body by ion implantation to form a reflective layer on one side surface of the first support substrate; the reflective layer is formed by ion implantation modification of the base material body; at least includes a low-sound-speed reflective layer and a high-sound-speed reflective layer arranged in a stacked manner along the thickness direction of the first support substrate;

[0089] S3: Form a piezoelectric film on the surface of the reflective layer facing away from the first support substrate, which is a heterogeneous material with the first support substrate and a heterogeneous material with the reflective layer. The acoustic impedances of the low-sound-speed reflective layer, the piezoelectric film, and the base material body increase in sequence, and the acoustic impedance of the high-sound-speed reflective layer is greater than that of the piezoelectric film;

[0090] In some embodiments, when the base material body is the first support substrate, ion implantation for modification can start from the surface of the base material body close to the piezoelectric film, or a part of the base material body that is not implanted and modified can be retained, and the reflective layer can be formed by modification starting from the inside of the base material body. The part of the base material body that is not implanted and modified is the second support substrate. Further, when ion implantation for modification starts from the surface of the base material body close to the piezoelectric film, a buffer layer is provided on the surface of the base material body close to the piezoelectric film by coating treatment before the ion implantation step, and the buffer layer is removed before the step of forming the piezoelectric film. By providing the buffer layer, ions are cached and diffused during the implantation process, so that ion implantation on the surface of the base material body close to the piezoelectric film can form a reflective layer on the surface of the base material body close to the piezoelectric film, rather than in the middle or other positions of the base material body. The coating treatment methods include any one of spin coating, sputtering, and evaporation. The methods for removing the buffer layer include any one of cleaning, etching, and dry etching; the materials of the buffer layer: the materials of the buffer layer include but are not limited to one or more of silicon nitride, silicon oxide, polysilicon, aluminum nitride, aluminum oxide, gallium nitride, quartz, benzocyclobutene, and polydimethylsiloxane.

[0091] In some embodiments, the base material body is the first support substrate. Before step S3, a step of providing a first dielectric layer on the surface of the reflective layer close to the piezoelectric film may be included. The first dielectric layer is located between the piezoelectric film and the reflective layer. The first dielectric layer can be formed on the surface of the reflective layer close to the piezoelectric film by at least techniques such as bonding and peeling, bonding and grinding, physical vapor deposition, chemical vapor deposition, magnetron sputtering, thermal oxidation deposition, etc.

[0092] In some embodiments, the base material body and the first support substrate are heterogeneous materials. Ion implantation for modification can start from the surface of the base material body close to the piezoelectric film, or a part of the base material body that is not implanted and modified can be retained, and modification is started from the inside of the base material body to form the reflective layer. The part of the base material body that is not implanted and modified is the second dielectric layer. Further, when ion implantation for modification starts from the surface of the base material body close to the piezoelectric film, a buffer layer is provided on the surface of the base material body close to the piezoelectric film by coating treatment before the ion implantation step, and the buffer layer is removed before the step of forming the piezoelectric film. By providing the buffer layer, ions are cached and diffused during implantation, so that ion implantation on the surface of the base material body close to the piezoelectric film can form a reflective layer on the surface of the base material body close to the piezoelectric film, rather than in the middle or other positions of the base material body. The coating treatment methods include any one of spin coating, sputtering, and evaporation. The methods of removing the buffer layer include any one of cleaning, etching, and dry etching.

[0093] In some embodiments, the base material body and the first support substrate are heterogeneous materials. Before step S3, a step of providing a second dielectric layer on the surface of the reflective layer close to the piezoelectric film may be included. The second dielectric layer is a heterogeneous material with the base material body. The second dielectric layer is located between the piezoelectric film and the reflective layer. The second dielectric layer can be formed on the surface of the reflective layer close to the piezoelectric film by at least techniques such as bonding and peeling, bonding and grinding, physical vapor deposition, chemical vapor deposition, magnetron sputtering, thermal oxidation deposition, etc.

[0094] S4: An electrode is formed on the surface of the piezoelectric film facing away from the reflective layer to obtain a high-frequency acoustic resonator.

[0095] On the other hand, an embodiment of the present application provides a high-frequency acoustic filter, and the high-frequency acoustic filter includes the high-frequency acoustic resonator as described above.

[0096] The following refers to Figures 1-15The specific embodiments of the present application will be introduced in combination with the above-mentioned high-frequency acoustic wave resonator and its preparation method. The following embodiments more specifically describe the technical solutions of the present application. These embodiments are only for illustrative purposes, because various modifications and changes are obvious to those skilled in the art within the scope of the disclosure of the present application. The reagents used in the embodiments can be obtained commercially or synthesized according to conventional methods, and can be used directly without further treatment. In addition, the instruments and devices used in the embodiments can be obtained commercially.

[0097] In the following embodiments and comparative examples, Y128-cut LiNbO3 is used as the piezoelectric film, and metallic aluminum is used as the surface interdigital electrode assembly to excite the A1 mode; the thickness of the interdigital electrode is 80 nm, the material of the interdigital electrode is metallic aluminum, the interdigital period λ is 2.63 μm, the duty cycle is 0.5, and the thickness of the Y128-cut LiNbO3 film is 395 nm. The wavelength of the target acoustic wave is defined by the interdigital period λ, that is, the numerical value of the interdigital period λ is the same as the wavelength of the target acoustic wave. The admittance response curves of the high-frequency acoustic wave resonators provided in the following embodiments and comparative examples are obtained through simulation as Figures 7-14 shown.

[0098] Example 1

[0099] This embodiment provides a high-frequency acoustic wave resonator. Referring to Figure 1 , it includes a first support substrate 1, a reflective layer 2, a piezoelectric film 3, and an interdigital electrode 4 stacked in sequence. The material of the first support substrate 1 is SiC, and the material of the reflective layer 2 is the same as that of the first support substrate 1. The reflective layer 2 includes five low-sound-speed reflective layers 2 and five high-sound-speed reflective layers 2. Among them, the modification coefficients of the five low-sound-speed reflective layers 2 are all 0.04, and the thicknesses are all λ / 8. The modification coefficients of the five identical high-sound-speed reflective layers 2 are all 0.9, and the thicknesses are all λ / 4. The high-frequency acoustic wave resonator is simulated to excite the A1 mode, and the admittance response curve and the vibration mode at the resonance frequency point of the acoustic wave resonator are obtained, as Figure 7 shown in Figures (a) and (b) in the middle. It can be seen from the admittance response curve of the acoustic wave resonator that the resonance peak of the A1 mode (the first-order antisymmetric Lamb wave mode) appears, the resonance frequency is 5510 MHz, the electromechanical coupling coefficient is 18.47%, and the admittance ratio exceeds 100 dB, showing the effective excitation of high-sound-speed acoustic waves; from Figure 7 (b), it can be seen from the vibration mode that the acoustic wave energy (the light-colored part) is concentrated on one side of the resonator close to the piezoelectric film 3, showing the effective constraint of the resonator structure on the acoustic wave energy.

[0100] Example 2

[0101] This embodiment provides a high-frequency acoustic wave resonator. Referring to Figure 2, including a first support substrate 1, a reflective layer 2, a first dielectric layer 6, a piezoelectric film 3, and interdigital electrodes 4 that are stacked in sequence. The material of the first support substrate 1 is SiC, the material of the first dielectric layer 6 is SiO2, and the material of the reflective layer 2 is the same as that of the first support substrate 1. The thickness of the first dielectric layer 6 is λ / 4. The reflective layer 2 includes five low-sound-speed reflective layers 2 and five high-sound-speed reflective layers 2. Among them, the modification coefficients of the five low-sound-speed reflective layers 2 are all 0.04, and the thicknesses are all λ / 8. The modification coefficients of the five identical high-sound-speed reflective layers 2 are all 0.9, and the thicknesses are all λ / 4. Among them, the reflective layer 2 closest to the first dielectric layer 6 is a low-sound-speed reflective layer 2. As Figure 8 is the simulated admittance response curve of the acoustic wave resonator. At this time, the A1 mode is also effectively excited, the resonance frequency is 5570 MHz, the electromechanical coupling coefficient is 9.75%, and the admittance ratio is about 88 dB.

[0102] Example 3

[0103] This example provides a high-frequency acoustic wave resonator. Refer to Figure 1 , the same parts as in Example 1 will not be elaborated. The differences from Example 1 are as follows: In this example, the material of the first support substrate 1 is Si. The reflective layer 2 includes five low-sound-speed reflective layers 2 and five high-sound-speed reflective layers 2. Among them, the modification coefficients of the five low-sound-speed reflective layers 2 are all 0.1, and the thicknesses are all λ / 8. The modification coefficients of the five identical high-sound-speed reflective layers 2 are all 1, and the thicknesses are all λ / 8. Among them, the reflective layer 2 closest to the piezoelectric film 3 is a low-sound-speed reflective layer 2. As Figure 9 is the simulated admittance response curve of the acoustic wave resonator. At this time, the A1 mode is effectively excited, the resonance frequency is 5246 MHz, the electromechanical coupling coefficient is 12.83%, and the admittance ratio is about 88 dB.

[0104] Example 4

[0105] This example provides a high-frequency acoustic wave resonator. Refer to Figure 1 , the same parts as in Example 1 will not be elaborated. The differences from Example 1 are as follows: In this example, the material of the first support substrate 1 is Sapphire. The reflective layer 2 includes five low-sound-speed reflective layers 2 and five high-sound-speed reflective layers 2. Among them, the modification coefficients of the five low-sound-speed reflective layers 2 are all 0.05, and the thicknesses are all λ / 8. The modification coefficients of the five identical high-sound-speed reflective layers 2 are all 1, and the thicknesses are all λ / 6. Among them, the reflective layer 2 closest to the piezoelectric film 3 is a low-sound-speed reflective layer 2. As Figure 9 is the simulated admittance response curve of the acoustic wave resonator. At this time, the A1 mode is effectively excited, the resonance frequency is 5460 MHz, the electromechanical coupling coefficient is 20.2%, and the admittance ratio exceeds 100 dB. In addition, for clear observation, the two curves have been set with a 30 dB offset on the vertical axis.

[0106] Example 5

[0107] This embodiment provides a high-frequency acoustic wave resonator. Referring to Figure 2 , the same parts as those in Embodiment 2 will not be described again. The difference between this embodiment and Embodiment 2 is that in this embodiment, the reflection layer 2 closest to the first dielectric layer 6 is a high sound velocity reflection layer 2. As Figure 8 is the simulated admittance response curve of the acoustic wave resonator. At this time, the A1 mode is also effectively excited, with a frequency of 5908 MHz, an electromechanical coupling coefficient of 5.57%, and an admittance ratio of 78 dB. In addition, for clear observation, the two curves have been set with a 30 dB offset on the vertical axis.

[0108] Example 6

[0109] This embodiment provides a high-frequency acoustic wave resonator. Referring to Figure 3 , it includes a first support substrate 1, a reflection layer 2, a second support substrate 5, a first dielectric layer 6, a piezoelectric film 3, and interdigital electrodes 4 stacked in sequence. The material of the first support substrate 1 is SiC, and the material of the first dielectric layer 6 is SiO2. The materials of the reflection layer 2, the first support substrate 1, and the second support substrate 5 are the same, that is, the reflection layer 2 in this embodiment starts to form from the inside of the first support substrate 1. The thickness of the first dielectric layer 6 is λ / 8, and the thickness of the second support substrate 5 is λ / 4. The reflection layer 2 includes five low sound velocity reflection layers 2 and five high sound velocity reflection layers 2. Among them, the modification coefficients of the five low sound velocity reflection layers 2 are all 0.04, and the thicknesses are all λ / 8. The modification coefficients of the five identical high sound velocity reflection layers 2 are all 0.9, and the thicknesses are all λ / 4. Among them, the reflection layer 2 closest to the second support substrate 5 is a low sound velocity reflection layer 2. As Figure 10 is the simulated admittance response curve of the acoustic wave resonator. At this time, the A1 mode is also effectively excited, with a frequency of 5996 MHz, an electromechanical coupling coefficient of 4.9%, and an admittance ratio of 76 dB.

[0110] Example 7

[0111] This embodiment provides a high-frequency acoustic wave resonator. Referring to Figure 4 , it includes a first support substrate 1, a reflection layer 2, a second dielectric layer 7, a piezoelectric film 3, and interdigital electrodes 4 stacked in sequence. The material of the first support substrate 1 is SiC, the material of the reflection layer 2 is aluminum nitride, and the material of the second dielectric layer 7 is SiO2. The reflection layer 2 includes seven low sound velocity reflection layers 2 and seven high sound velocity reflection layers 2. Among them, the modification coefficients of the seven low sound velocity reflection layers 2 are all 0.6, and the thicknesses are all λ / 8. The modification coefficients of the seven identical high sound velocity reflection layers 2 are all 3, and the thicknesses are all λ / 4. The thickness of the second dielectric layer 7 is λ / 10. As Figure 11It is the simulated admittance response curve of the acoustic wave resonator. At this time, the A1 mode is also effectively excited. The resonance frequency is 5270 MHz, the electromechanical coupling coefficient is 14.05%, and the admittance ratio exceeds 80 dB, showing good resonance performance and being able to effectively achieve high-frequency and large-bandwidth responses.

[0112] In addition, based on the structure of Embodiment 1, the number of stacked pairs of the reflective layer 2 is adjusted. One low-sound-speed reflective layer 2 + one high-sound-speed reflective layer 2 is a pair of reflective layers 2. Figure 13 It shows the change of the admittance response curve of the A1 mode when the number of stacked pairs ranges from 2 to 10. The number of low-sound-speed reflective layers 2 and high-sound-speed reflective layers 2 is represented by n1 and n2 respectively. When the number of stacked pairs is 2 pairs, the effective excitation of the A1 mode can already be achieved; as the number of stacked pairs continuously increases, the resonance peak and anti-resonance peak gradually become sharp, showing the effective excitation of the acoustic wave and also showing the effective constraint of the acoustic wave energy by the resonator structure. In actual applications, to achieve good energy constraint and high-frequency and large-bandwidth performance, while simplifying the preparation process, 2 to 5 pairs of built-in reflective layers 2 can be selected for preparation.

[0113] Based on the structure of Embodiment 1, the modification coefficient of the high-sound-speed reflective layer 2 is adjusted. Figure 14 It shows the change of the admittance response curve when the modification coefficient range of the high-sound-speed reflective layer 2 is 0.75 to 1.25 (the modification coefficient is represented by ξ in the figure). At this time, the modification coefficient of the low-sound-speed reflective layer 2 is 0.04. When the modification coefficient of the high-sound-speed reflective layer 2 is 0.75, the effective excitation of the A1 mode can already be achieved. As the modification coefficient increases, the resonance frequency of the A1 mode gradually increases, and the electromechanical coupling coefficient is about 18%, which can meet the device requirements of high frequency and large bandwidth.

[0114] Figure 15 It shows the structural schematic diagram when the electrode is a full-surface electrode. Refer to Figure 15 , the high-frequency acoustic wave resonator includes a first support substrate 1, a reflective layer 2, a surface electrode 8, a piezoelectric film 3, and a surface electrode 8 stacked in sequence. An electric field in the thickness direction is formed between the two surface electrodes 8 to excite the high-sound-speed acoustic wave in the piezoelectric film 3, and the reflective layer 2 constrains the high-sound-speed acoustic wave energy; at this time, the types of acoustic wave modes include but are not limited to high-sound-speed acoustic wave modes such as thickness longitudinal waves and thickness shear waves.

[0115] Comparative Example 1

[0116] This comparative example provides a high-frequency acoustic wave resonator. Refer to Figure 5 , which includes a first support substrate 1, a piezoelectric film 3, and interdigital electrodes 4 stacked in sequence. The material of the first support substrate 1 is SiC.

[0117] Comparative Example 2

[0118] This comparative example provides a high-frequency acoustic wave resonator. Refer to Figure 6 which includes a first support substrate 1, a third dielectric layer 9, a piezoelectric film 3, and interdigital electrodes 4 stacked in sequence. The material of the first support substrate 1 is SiC, and the material of the third dielectric layer is SiO2.

[0119] Comparative Example 3

[0120] This comparative example provides a high-frequency acoustic wave resonator. The same parts as those in Comparative Example 1 will not be described again. The difference from Comparative Example 1 is that the material of the first support substrate 1 in this comparative example is Si.

[0121] Comparative Example 4

[0122] This comparative example provides a high-frequency acoustic wave resonator. The same parts as those in Comparative Example 1 will not be described again. The difference from Comparative Example 1 is that the material of the first support substrate 1 in this comparative example is sapphire.

[0123] As Figure 12 shown, in Comparative Examples 1-4, due to the limited slow shear wave sound velocity of the first support substrate 1, the energy of the high sound velocity acoustic wave in the traditional acoustic wave resonator structure will leak into the support substrate, and the A1 mode with high sound velocity cannot be effectively excited. Therefore, there is no corresponding resonance peak of the A1 mode in the admittance curve.

[0124] It can be seen from the admittance response curves of the acoustic wave resonators in the above-mentioned embodiments and comparative examples that the resonance peaks of the A1 mode (the first-order antisymmetric Lamb wave mode with a sound velocity as high as 13000 m / s) appear in the high-frequency acoustic wave resonators in the embodiments, indicating that the A1 mode has been successfully excited in the acoustic wave resonators in the embodiments. This is because the reflection layer 2 in the embodiments of the present application reflects and constrains the high sound velocity acoustic wave energy layer by layer, realizing the effective excitation of the acoustic wave mode with high sound velocity and large electromechanical coupling coefficient. The larger the electromechanical coupling coefficient, the larger the bandwidth. The acoustic wave resonators in the above-mentioned embodiments all exhibit the advantages of high frequency and large bandwidth; and by using ion implantation to modify the support substrate, there is no need to suspend the device structure, no need to reduce the line width of the interdigital electrodes 4, and the operating frequency can be extended to more than 5 GHz while keeping the line width of the interdigital electrodes 4 greater than 600 nm. There is no need to etch the piezoelectric film 3, retaining the structural integrity of the piezoelectric film 3, which can enhance the structural stability and heat dissipation ability.

[0125] The above description has fully disclosed the specific implementation manners of the present application. It should be noted that any modification made by those skilled in the art to the specific implementation manners of the present application does not depart from the scope of the claims of the present application. Correspondingly, the scope of the claims of the present application is not limited to the foregoing specific implementation manners.

Claims

1. A high-frequency acoustic resonator, characterized in that, Comprising: A first support substrate; A reflective layer located on one surface of the first support substrate, the reflective layer being formed by ion implantation modification of a base material body; at least including a low sound velocity reflective layer and a high sound velocity reflective layer stacked along the thickness direction of the first support substrate; A piezoelectric film located on the surface of the reflective layer facing away from the first support substrate, being a heterogeneous material with the first support substrate and also a heterogeneous material with the reflective layer, the sound impedance of the low sound velocity reflective layer, the piezoelectric film, and the base material body increases in sequence, and the sound impedance of the high sound velocity reflective layer is greater than that of the piezoelectric film; A first dielectric layer located between the reflective layer and the piezoelectric film, the first dielectric layer being a heterogeneous material with the piezoelectric film and also a heterogeneous material with the first support substrate; A second dielectric layer is further provided between the piezoelectric film and the reflective layer; An electrode located on the surface of the piezoelectric film facing away from the reflective layer, wherein the electrode is a patterned electrode, the period of the patterned electrode is λ, and the thickness of the second dielectric layer does not exceed 0.4λ.

2. The high-frequency acoustic wave resonator according to claim 1, characterized in that, The reflective layer satisfies at least one of the following characteristics: The low sound velocity reflective layer includes 2 - 5 layers; The high sound velocity reflective layer includes 2 - 5 layers; The modification coefficient of the low sound velocity reflective layer is 0.01 - 0.6; The modification coefficient of the high sound velocity reflective layer is 0.7 - 3, and the modification coefficient is the ratio of the elastic coefficient of the base material body after modification to the elastic coefficient before modification.

3. A high-frequency acoustic wave resonator according to claim 1 or 2, characterized in that, The high-frequency acoustic wave resonator satisfies at least one of the following characteristics: The ratio of the slow shear wave sound velocity of the base material body to the target acoustic wave sound velocity propagating in the piezoelectric layer is not less than 0.4; The material of the first support substrate includes one or more of silicon carbide, silicon, sapphire, quartz, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, diamond, diamond-like, boron carbide, boron nitride, and zirconia; The material of the base material body includes one or more of silicon carbide, silicon, sapphire, quartz, aluminum nitride, silicon nitride, zinc oxide, aluminum oxide, diamond, diamond-like, boron carbide, boron nitride, and zirconia; The material of the base material body includes one or more of silicon oxide, fluorine-containing silicon oxide, silicon oxynitride, polysilicon, tantalum pentoxide, and tellurium dioxide; The material of the piezoelectric layer includes one or more of lithium niobate, potassium niobate, lithium tantalate, aluminum nitride, quartz, and zinc oxide; The electrode is a full-surface electrode.

4. A high-frequency acoustic resonator according to claim 3, characterized in that The thickness of the reflective layer satisfies at least one of the following characteristics: The thickness of one layer of the low sound velocity reflective layer is 0.1 - 0.4λ; The thickness of one layer of the high sound velocity reflective layer is 0.1 - 0.4λ.

5. A high-frequency acoustic resonator according to claim 3, characterized in that, The base material body and the first support substrate are of the same material.

6. A high-frequency acoustic resonator according to claim 5, characterized in that, A second support substrate is further provided between the reflective layer and the piezoelectric film, and the second support substrate satisfies at least one of the following characteristics: The second support substrate and the first support substrate are of the same material; The thickness of the second support substrate does not exceed 0.4λ.

7. A high-frequency acoustic resonator according to claim 5, characterized in that, The first dielectric layer satisfies at least one of the following characteristics: The material of the first dielectric layer includes one or more of silicon oxide, fluorine-containing silicon oxide, silicon oxynitride, polysilicon, aluminum nitride, tantalum pentoxide, tellurium dioxide; The thickness of the first dielectric layer is 0.1 - 1λ.

8. A method for preparing a high-frequency acoustic resonator, characterized in that, The method includes the following steps: Providing a first support substrate and a base material body which are stacked; Modifying the base material body by ion implantation to form a reflective layer on one surface of the first support substrate; the reflective layer is formed by ion implantation modification of the base material body; it includes at least one low acoustic velocity reflective layer and one high acoustic velocity reflective layer which are stacked along the thickness direction of the first support substrate; Forming a first dielectric layer on the surface of the reflective layer facing away from the first support substrate, and the first dielectric layer and the first support substrate are heterogeneous materials to each other; Forming a second dielectric layer on the surface of the reflective layer facing away from the first support substrate layer; Forming a piezoelectric film on the surface of the reflective layer facing away from the first support substrate layer, the piezoelectric film and the first support substrate are heterogeneous materials to each other, and are heterogeneous materials to the reflective layer and the first dielectric layer to each other. The acoustic impedance of the low acoustic velocity reflective layer, the piezoelectric film, and the base material body increases in sequence, and the acoustic impedance of the high acoustic velocity reflective layer is greater than that of the piezoelectric film; Forming an electrode on the surface of the piezoelectric film facing away from the reflective layer to obtain the high-frequency acoustic wave resonator, wherein the electrode is a patterned electrode, the period of the patterned electrode is λ, and the thickness of the second dielectric layer does not exceed 0.4λ.

9. The manufacturing method of a high-frequency acoustic resonator according to claim 8, characterized in that, Before the ion implantation step, it further includes setting a buffer layer on the surface of the base material body facing away from the first support substrate, and before the step of forming the piezoelectric film, it further includes removing the buffer layer.

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