Resonant assembly and preparation method thereof, and filter

Abstract

The invention discloses a resonance assembly and a preparation method thereof, and a filter, and relates to the technical field of micro electro mechanical systems, the resonance assembly comprises a substrate, and a piezoelectric layer, a first composite layer, a dielectric layer and a second composite layer which are sequentially arranged on the substrate, the first composite layer comprises an interdigital electrode and a first electrode plate which are arranged on the same layer, and the second composite layer comprises a second electrode plate which is arranged on the same layer; the second composite layer comprises an electrode leading-out structure and a second electrode plate, the electrode leading-out structure penetrates through the dielectric layer and is connected with the interdigital electrode, the projection of the first electrode plate and the projection of the second electrode plate on the substrate have an overlapped area, and the overlapped part of the projection of the first electrode plate and the projection of the second electrode plate on the substrate forms a capacitor. According to the resonant component, the preparation method thereof and the filter, the size of the filter can be reduced, and the performance of the filter is improved.

Description

Technical Field

[0001] The present application relates to the technical field of micro-electromechanical systems, and in particular to a resonant component and a preparation method thereof, and a filter. Background Art

[0002] In 4G communication technology and before 4G communication technology, due to the relatively narrow bandwidth of the frequency band definition, according to the needs of the RF system, the selection of electromagnetic or acoustic filters can meet the performance requirements. However, after entering the 5G, 6G and Wi-Fi 7 stages, the frequency band definition specifications have undergone major changes. All frequency bands are set to have a large bandwidth of more than 500MHz, and the frequency band spacing is gradually narrowed. Rigidity requires filters that can support large bandwidth and high out-of-band suppression at the same time. Traditional electromagnetic filters and acoustic filters cannot meet the requirements. Hybrid filters composed of acoustic resonators and LC circuits have become a universal solution for the next stage of 5G, WiFi 7 and other communications.

[0003] The hybrid filter is a device formed by connecting inductors and capacitors in series or in parallel at both ends of the basic series or parallel units of the acoustic wave resonator. The series or parallel capacitors and inductors can shift the series resonant frequency or parallel resonant frequency of the resonator. By utilizing this feature, the effective electromechanical coupling coefficient and the bandwidth of the resonator after the hybrid design can be increased by reasonably designing the value and connection method of the IPD element. When the prior art integrates the resonator with the capacitor and inductor, a patch connection method is used, which requires additional routing, and its size is larger than that of the resonator, which reduces the filter performance and cannot reduce the area, greatly limiting the performance of the surface acoustic wave filter. Summary of the invention

[0004] The purpose of the present application is to provide a resonant component and a preparation method thereof, and a filter, which can reduce the volume of the filter and improve the performance of the filter.

[0005] On the one hand, an embodiment of the present application provides a resonant component, including a substrate and a piezoelectric layer, a first composite layer, a dielectric layer and a second composite layer arranged on the substrate in sequence, the first composite layer including an interdigitated electrode and a first electrode plate arranged in the same layer, the second composite layer including an electrode lead-out structure and a second electrode plate, the electrode lead-out structure passes through the dielectric layer and is connected to the interdigitated electrode, the projections of the first electrode plate and the second electrode plate on the substrate have an overlapping area, and the overlapping portion of the projections of the first electrode plate and the second electrode plate on the substrate forms a capacitor.

[0006] As an implementable manner, the second electrode plate includes a plurality of sub-plates arranged at intervals, and the projections of the plurality of sub-plates on the substrate along the hierarchical direction are all within the projection range of the first electrode plate. Each sub-plate forms a sub-capacitor with the first electrode plate, and the plurality of sub-capacitors are connected in series or in parallel.

[0007] As an implementable manner, the second electrode plate includes two sub-plates, namely a first plate and a second plate, and projections of the first plate and the second plate in the hierarchical direction both overlap with the projection of the first electrode plate.

[0008] As an implementable manner, the first electrode plate includes a plurality of spaced-apart sub-electrode plates, the plurality of sub-electrode plates are arranged opposite to each other in a layer, and two of the sub-electrode plates are connected to form a second capacitor connected in parallel or in series.

[0009] As an implementable manner, a plurality of sub-electrode plates extend into the dielectric layer to increase the relative areas of the sub-electrode plates.

[0010] As an implementable method, the piezoelectric layer is divided into an effective resonance area and a peripheral area located outside the effective resonance area, the interdigitated electrodes are located in the effective resonance area, the first electrode plate is located in the peripheral area, and an acoustic reflection structure is also provided at the boundary of the effective resonance area of ​​the piezoelectric layer.

[0011] As an implementable manner, the sound reflection structure includes grooves arranged at the boundaries of the effective resonance area.

[0012] As an implementable manner, an oxide layer is further provided between the substrate and the piezoelectric layer.

[0013] Another aspect of an embodiment of the present application provides a filter, comprising a plurality of resonant components cascaded according to a preset circuit, wherein at least one resonant component is the above-mentioned resonant component.

[0014] On the other hand, an embodiment of the present application provides a method for preparing a resonant component, which is used to prepare the above-mentioned resonant component, including: providing a substrate and sequentially forming a piezoelectric layer and a first metal layer on the substrate; patterning the first metal layer to form a first composite layer, the first composite layer including interdigitated electrodes and a first electrode plate arranged on the same layer; forming a dielectric layer on the first composite layer and patterning it so that the contact points of the interdigitated electrodes are exposed; forming a second metal layer on the dielectric layer and patterning it to form a second composite layer, the second composite layer including an electrode lead-out structure and a second electrode plate, the electrode lead-out structure passes through the dielectric layer and is connected to the contact points of the interdigitated electrodes, the projections of the first electrode plate and the second electrode plate on the substrate have an overlapping area, and the overlapping part of the projections of the first electrode plate and the second electrode plate on the substrate forms a capacitor.

[0015] The beneficial effects of the embodiments of the present application include:

[0016] The resonant component provided by the present application includes a substrate and a piezoelectric layer, a first composite layer, a dielectric layer and a second composite layer arranged on the substrate in sequence, the first composite layer includes an interdigitated electrode and a first electrode plate arranged in the same layer, the second composite layer includes an electrode lead-out structure and a second electrode plate, the electrode lead-out structure passes through the dielectric layer and is connected to the interdigitated electrode, the interdigitated electrode is powered by the electrode lead-out structure, so that the piezoelectric layer resonates, the projections of the first electrode plate and the second electrode plate on the substrate have an overlapping area, the overlapping part of the projections of the first electrode plate and the second electrode plate on the substrate forms a capacitor, so that the capacitor is formed inside the resonant component, that is, the capacitor is integrated into the resonant component, and compared with the patch connection capacitor in the prior art, the area is smaller, no additional lead-out path is required, and the corresponding electrical parasitics are avoided, thereby improving the performance of the resonant component. Therefore, the resonant component of the embodiment of the present application can reduce the volume of the filter and improve the performance of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 One of the structural schematic diagrams of a resonant component provided in an embodiment of the present application;

[0019] Figure 2 A second structural schematic diagram of a resonant component provided in an embodiment of the present application;

[0020] Figure 3 A third structural schematic diagram of a resonant component provided in an embodiment of the present application;

[0021] Figure 4 A fourth structural schematic diagram of a resonant component provided in an embodiment of the present application;

[0022] Figure 5 A fifth structural diagram of a resonant component provided in an embodiment of the present application;

[0023] Figure 6 A sixth structural diagram of a resonant component provided in an embodiment of the present application;

[0024] Figure 7 A seventh structural diagram of a resonant component provided in an embodiment of the present application;

[0025] Figure 8 A schematic diagram of the structure of a capacitor provided in an embodiment of the present application;

[0026] Fig. 9 A flow chart of a method for preparing a resonance component provided in an embodiment of the present application;

[0027] Fig.10 One of the state diagrams of a method for preparing a resonant component provided in an embodiment of the present application;

[0028] Fig.11 A second state diagram of a method for preparing a resonant component provided in an embodiment of the present application;

[0029] Fig.12 The third state diagram of a method for preparing a resonant component provided in an embodiment of the present application.

[0030] Icon: 100 - resonant component; 101 - substrate; 102 - oxide layer; 103 - piezoelectric layer; 104 - first electrode plate; 1041 - sub-electrode plate; 110 - interdigitated electrode; 105 - dielectric layer; 106 - second electrode plate; 1061 - first plate; 1062 - second plate; 120 - electrode lead structure. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] Surface acoustic wave filters are widely used due to their low cost, high quality factor, good out-of-band suppression and other advantages. Surface acoustic wave filters are composed of multiple resonators cascaded in a specific circuit. Due to the limitation of the electromechanical coupling coefficient of the piezoelectric layer material of the resonator, its bandwidth is relatively small. In practical applications, passive devices such as capacitors or inductors are usually added as matching circuits or to increase the bandwidth of the filter, adjust the filtering characteristics, etc. In the prior art, the connection of capacitors is usually achieved by using labeled capacitors, which occupies a larger volume.

[0035] The present application embodiment provides a resonant component 100, such as Figure 1 and Figure 2 As shown, it includes a substrate 101 and a piezoelectric layer 103, a first composite layer, a dielectric layer 105 and a second composite layer which are sequentially arranged on the substrate 101. The first composite layer includes an interdigitated electrode 110 and a first electrode plate 104 which are arranged in the same layer. The second composite layer includes an electrode lead-out structure 120 and a second electrode plate 106. The electrode lead-out structure 120 passes through the dielectric layer 105 and is connected to the interdigitated electrode 110. The projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 have an overlapping area. The overlapping portion of the projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 forms a capacitor.

[0036] The resonant component 100 provided in the embodiment of the present application integrates the resonator and the capacitor in the prior art. Specifically, the resonant component 100 includes a substrate 101 and a piezoelectric layer 103, a first composite layer, a dielectric layer 105 and a second composite layer sequentially arranged on the substrate 101, wherein the first composite layer includes a forked electrode 110, and the second composite layer includes an electrode lead-out structure 120, the electrode lead-out structure 120 passes through the dielectric layer 105 and is connected to the forked electrode 110, and the forked electrode 110 is powered by the electrode lead-out structure 120, so as to generate a voltage between the forked electrode 110 and the forked electrode 110. A voltage difference is formed between the two electrodes, and the piezoelectric layer 103 vibrates and resonates under the action of the voltage difference to realize the function of the resonator; in addition, the first composite layer also includes a first electrode plate 104 arranged in the same layer as the interdigitated electrode 110, and the second composite layer also includes a second electrode plate 106 arranged in the same layer as the electrode lead-out structure 120, wherein the projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 have an overlapping area, and the overlapping portion of the projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 forms a capacitor to realize the function of the capacitor. Therefore, the embodiment of the present application can integrate the capacitor into the resonator to form the resonant component 100, avoiding the problem of increased area caused by external capacitor attachment and introduction of corresponding electrical parasitics in the prior art, reducing the area of ​​the resonant component 100, and improving the performance of the resonant component 100.

[0037] In the resonant component 100, the specific structure of the substrate 101 is not limited in the present embodiment, and can be, for example, as follows: Figure 1 and Figure 2 As shown in the silicon substrate, sapphire substrate, or as Figure 4 The substrate shown is formed by setting an oxide layer on a silicon substrate, and those skilled in the art can make specific settings according to actual conditions.

[0038] It can be understood that the interdigitated electrode 110 includes positive electrodes and negative electrodes arranged alternately, wherein the same side ends of multiple positive electrodes are connected by a positive bus bar, and the same side ends of multiple negative electrodes are connected by a negative bus bar. Powering one positive electrode can realize powering all positive electrodes. Similarly, powering one negative electrode can realize powering all negative electrodes. Therefore, the electrode lead structure 120 of the embodiment of the present application has two terminals, such as Figure 1 and Figure 2 shown.

[0039] The projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 may be completely overlapped or partially overlapped.

[0040] In addition, the dielectric layer 105 is used to isolate the first electrode plate 104 and the second electrode plate 106, and to protect the interdigital electrode 110. The specific material is not limited in the embodiment of the present application, and those skilled in the art can set it according to actual conditions. For example, it can be an oxide layer 102, a nitride layer, etc., and commonly used ones are silicon dioxide and silicon nitride.

[0041] In the resonance component 100 provided in the embodiment of the present application, the overlapping portion of the first electrode plate 104 and the second electrode plate 106 projected on the substrate 101 forms a capacitor, so that the capacitor is formed inside the resonance component 100, that is, the capacitor is integrated into the resonance component 100. Compared with the patch connection capacitor in the prior art, the area is smaller and no additional lead-out path is required to avoid corresponding electrical parasitics, thereby improving the performance of the resonance component 100. Therefore, the resonance component 100 in the embodiment of the present application can reduce the volume of the filter and improve the performance of the filter.

[0042] Optional, such as Figure 2 As shown, the second electrode plate 106 includes a plurality of sub-plates arranged at intervals, and the projections of the plurality of sub-plates on the substrate 101 along the hierarchical direction are all within the projection range of the first electrode plate 104, each sub-plate and the first electrode plate 104 form a sub-capacitor, and the plurality of sub-capacitors are connected in series or in parallel.

[0043] The second electrode plate 106 includes a plurality of sub-plates, each of which forms a sub-capacitor with the first electrode plate 104. In this way, the plurality of sub-capacitors can be connected in series or in parallel according to actual conditions to achieve different capacitance value combinations. In addition, each sub-capacitor can also be cascaded in the filter circuit as a capacitor device, thereby increasing the applicability of the resonant component 100.

[0044] When the second electrode plate 106 includes a plurality of sub-plates, the first electrode plate 104 may be an integral structure or may be configured as a plurality of sub-plates, as long as a plurality of sub-capacitors can be realized.

[0045] In one possible implementation of the embodiment of the present application, Figure 2 As shown, the second electrode plate 106 includes two sub-plates, namely a first plate 1061 and a second plate 1062 , and the projections of the first plate 1061 and the second plate 1062 in the hierarchical direction overlap with the projection of the first electrode plate 104 .

[0046] When the second electrode plate 106 includes two first plates 1061 and a second plate 1062, the first plate 1061 and the first electrode plate 104 form a first sub-capacitor, and the second plate 1062 and the first electrode plate 104 form a second sub-capacitor. Since the first electrode plate 104 is an integral body, at this time, the first sub-capacitor and the second sub-capacitor are connected in series. At this time, the two end connection points of the capacitor formed by the first sub-capacitor and the second sub-capacitor in series are the first plate 1061 and the second plate 1062 respectively. Since the first plate 1061 and the second plate 1062 are both located on the upper surface of the resonant component 100, it is convenient to connect the capacitor to the resonator or other resonant components 100.

[0047] Optional, such as Figure 5 , Figure 6 and Figure 7 As shown, the first electrode plate 104 includes a plurality of spaced-apart sub-electrode plates 1041 , the plurality of sub-electrode plates 1041 are arranged opposite to each other in a layer, and two of the sub-electrode plates 1041 are connected to form a second capacitor connected in parallel or in series.

[0048] The capacitor is formed in the layer direction, and the second capacitor is formed in the layer, so that various forms of capacitors are formed in the resonant component 100, which is convenient for subsequent cascading. In addition, the second capacitor is formed in the layer, and the distance between two adjacent sub-electrode plates 1041 can be adjusted according to actual conditions to adjust the size of the capacitance value.

[0049] Specifically, the number of the sub-electrode plates 1041 is not limited in the present embodiment, and can be two, three or four by way of example. Figure 5 The two sub-electrode plates 1041 shown in the figure are arranged opposite to each other to form a second capacitor; Figure 7 and Figure 8 The three sub-electrode plates 1041 shown in the figure, wherein the two sub-electrode plates 1041 with a larger spacing are used as main electrode plates, and the other one is used as a correction electrode plate. Specifically, as shown in FIG. Figure 8 As shown, the two left sub-electrode plates 1041 are used as the main electrode plates, and the right sub-electrode plate 1041 is used as the correction electrode plate. When the capacitance between the two left sub-electrode plates 1041 is small, the right electrode plate is connected to the left electrode plate to increase the capacitance; Figure 6The four sub-electrode plates 1041 shown are plate 1, plate 2, plate 3 and plate 4 from left to right, wherein the distance between plate 1 and plate 2 is 1 / 10 of the distance between plate 2 and plate 3, wherein plate 1 and plate 3 are main electrode plates, and plate 2 and plate 4 are correction electrode plates, and when the capacitance value between plate 1 and plate 3 is small, plate 1 can be connected to plate 4 to increase the capacitance value; when the capacitance value between plate 1 and plate 3 is large, plate 2 can be connected to plate 3 to reduce the capacitance value.

[0050] In practical applications, the second capacitor and the first capacitor may exist in the resonant component 100 separately or simultaneously.

[0051] In one possible implementation of the embodiment of the present application, Figure 6 As shown, a plurality of sub-electrode plates 1041 extend into the dielectric layer 105 , thereby increasing the relative area of ​​the sub-electrode plates 1041 .

[0052] Extending multiple sub-electrode plates 1041 into the dielectric layer 105 can increase the relative area between the sub-electrode plates 1041, thereby increasing the capacitance and facilitating the setting of a larger capacitance. Those skilled in the art can set the depth of the sub-electrode plates 1041 extending into the dielectric layer 105 according to actual conditions.

[0053] When Figure 7 As shown, when the sub-electrode plate 1041 extends to the surface of the dielectric layer 105 , the second electrode plate 106 may not be provided to avoid contact between the sub-electrode plate 1041 and the second electrode plate 106 .

[0054] Optional, such as Figure 2 , Figure 3 and Figure 4 As shown, the piezoelectric layer 103 is divided into an effective resonance area and a peripheral area located outside the effective resonance area. The interdigitated electrodes 110 are located in the effective resonance area, the first electrode plate 104 is located in the peripheral area, and an acoustic reflection structure is also provided at the boundary of the effective resonance area of ​​the piezoelectric layer 103.

[0055] According to the working principle of the above-mentioned resonator, the voltage difference formed on the forked electrode 110 generates a resonant sound wave. In order to prevent the sound wave from leaking out of the effective resonance area and causing leakage of the sound wave, the embodiment of the present application is further provided with a sound reflection structure at the boundary of the effective resonance area of ​​the piezoelectric layer 103. The sound reflection structure reflects the sound waves propagating to the boundary of the effective resonance area back into the effective resonance area, thereby improving the Q value of the resonance component 100.

[0056] In one implementable manner of the embodiment of the present application, the sound reflection structure includes grooves arranged at the boundaries of the effective resonance area.

[0057] The groove is filled with air, and the air and the piezoelectric layer 103 have different acoustic reflection coefficients, thereby forming an acoustic reflection structure at the interface between the air and the piezoelectric layer 103, reflecting the sound waves propagating to the interface back into the effective resonance area for propagation, thereby avoiding the leakage of sound waves and improving the Q value of the resonance component 100.

[0058] In practical applications, the groove can be filled with a sound-reflecting material. The sound-reflecting material has a large difference in sound reflection coefficient with the piezoelectric layer 103, which can improve the reflection effect at the interface, thereby further improving the Q value of the resonant component 100. The specific sound-reflecting material is not limited in the embodiments of this application. For example, it can be silicon oxide, silicon nitride, etc. When the dielectric layer 105 is an oxide layer 102, the dielectric layer 105 can be directly filled in the groove. The dielectric layer 105 filled in the groove forms a sound-reflecting structure with the piezoelectric layer 103. In this way, the groove can be filled when the dielectric layer 105 is set, and the steps of releasing the sacrificial material in the groove or filling the groove can be saved, thereby simplifying the manufacturing steps of the resonant component 100.

[0059] Optional, such as Figure 4 As shown, an oxide layer is also provided between the substrate 101 and the piezoelectric layer 103. The substrate 101 and the oxide layer serve as the substrate 101 of the resonant component 100 and are used to provide support. In addition, the oxide layer 102 has good insulation properties and can improve the insulation properties of the substrate 101.

[0060] The embodiment of the present application also discloses a filter, including a plurality of resonant components 100 cascaded according to a preset circuit, wherein at least one resonant component 100 is the above-mentioned resonant component 100. The filter includes the same structure and beneficial effects as the resonant component 100 in the aforementioned embodiment. The structure and beneficial effects of the resonant component 100 have been described in detail in the aforementioned embodiment, and will not be repeated here.

[0061] The present application also discloses a method for preparing the resonant component 100. Fig. 9 As shown, the method for preparing the above-mentioned resonant component 100 includes:

[0062] S10: Fig.10 As shown, a substrate 101 is provided and a piezoelectric layer 103 and a first metal layer are sequentially formed on the substrate 101;

[0063] The piezoelectric layer 103 and the first metal layer can be formed by chemical vapor deposition or physical vapor deposition. The material of the piezoelectric layer 103 can be piezoelectric materials such as lithium tantalate, lithium niobate, etc. The first metal layer can be metal such as aluminum, copper, etc.

[0064] S20: Fig.10As shown, the first metal layer is patterned to form a first composite layer, and the first composite layer includes interdigitated electrodes 110 and a first electrode plate 104 arranged in the same layer;

[0065] Patterning can be performed by dry etching or wet etching using a mask.

[0066] S30: Fig.11 As shown, a dielectric layer 105 is formed on the first composite layer and patterned so that the contact points of the interdigital electrodes 110 are exposed;

[0067] S40: Fig.12 As shown, a second metal layer is formed on the dielectric layer 105 and patterned to form a second composite layer, the second composite layer includes an electrode lead-out structure 120 and a second electrode plate 106, the electrode lead-out structure 120 passes through the dielectric layer 105 and is connected to the contact point of the interdigitated electrode 110, the projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 have an overlapping area, and the overlapping portion of the projections of the first electrode plate 104 and the second electrode plate 106 on the substrate 101 forms a capacitor.

[0068] The overlapping portion of the first electrode plate 104 and the second electrode plate 106 projected on the substrate 101 forms a capacitor, so that the capacitor is formed inside the resonant component 100, that is, the capacitor is integrated into the resonant component 100. Compared with the patch connection capacitor in the prior art, the area is smaller and no additional lead-out path is required to avoid corresponding electrical parasitics, thereby improving the performance of the resonant component 100. Therefore, the resonant component 100 of the embodiment of the present application can reduce the volume of the filter and improve the performance of the filter.

[0069] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A resonant component, characterized in that: It includes a substrate and a piezoelectric layer, a first composite layer, a dielectric layer and a second composite layer which are sequentially arranged on the substrate, the first composite layer includes interdigitated electrodes and a first electrode plate arranged in the same layer, the second composite layer includes an electrode lead-out structure and a second electrode plate, the electrode lead-out structure passes through the dielectric layer and is connected to the interdigitated electrodes, the projections of the first electrode plate and the second electrode plate on the substrate have an overlapping area, and the overlapping parts of the projections of the first electrode plate and the second electrode plate on the substrate form a capacitor.

2. The resonant component according to claim 1, characterized in that: The second electrode plate includes a plurality of sub-plates arranged at intervals, and projections of the plurality of sub-plates on the substrate along the hierarchical direction are all within the projection range of the first electrode plate. Each of the sub-plates and the first electrode plate forms a sub-capacitor, and the plurality of sub-capacitors are connected in series or in parallel.

3. The resonant component according to claim 2, characterized in that: The second electrode plate includes two sub-plates, namely a first plate and a second plate, and projections of the first plate and the second plate in the hierarchical direction overlap with the projection of the first electrode plate.

4. The resonant component according to claim 1, characterized in that: The first electrode plate includes a plurality of sub-electrode plates arranged at intervals, the plurality of sub-electrode plates are arranged opposite to each other in a layer, and two of the sub-electrode plates are connected to form a second capacitor connected in parallel or in series.

5. The resonant component according to claim 4, characterized in that: The plurality of sub-electrode plates extend into the dielectric layer to increase the relative areas of the sub-electrode plates.

6. The resonant component according to claim 1, characterized in that: The piezoelectric layer is divided into an effective resonance area and a peripheral area located outside the effective resonance area. The interdigitated electrodes are located in the effective resonance area. The first electrode plate is located in the peripheral area. An acoustic reflection structure is also provided at the boundary of the effective resonance area of ​​the piezoelectric layer.

7. The resonant component according to claim 6, characterized in that: The sound reflection structure includes grooves arranged at the boundary of the effective resonance area.

8. The resonant component according to claim 1, characterized in that An oxide layer is further arranged between the substrate and the piezoelectric layer.

9. A filter, characterized in that: It comprises a plurality of resonant components cascaded according to a preset circuit, wherein at least one of the resonant components is the resonant component according to any one of claims 1 to 8.

10. A method for preparing a resonant component, characterized in that: Used to prepare the resonant component according to any one of claims 1 to 8, comprising: Providing a substrate and sequentially forming a piezoelectric layer and a first metal layer on the substrate; Patterning the first metal layer to form a first composite layer, wherein the first composite layer includes interdigitated electrodes and a first electrode plate disposed in the same layer; forming a dielectric layer on the first composite layer and patterning the dielectric layer so that the contact points of the interdigital electrodes are exposed; A second metal layer is formed on the dielectric layer and patterned to form a second composite layer, the second composite layer includes an electrode lead-out structure and a second electrode plate, the electrode lead-out structure passes through the dielectric layer and is connected to the contact point of the interdigitated electrode, the projections of the first electrode plate and the second electrode plate on the substrate have an overlapping area, and the overlapping portion of the projections of the first electrode plate and the second electrode plate on the substrate forms a capacitor.

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