Bulk acoustic wave resonator, preparation method thereof and filter
By integrating the interdigit capacitor structure outside the resonant area in the bulk acoustic wave resonator, the problem of external capacitance leads and large area is solved, and the device performance is improved.
Patent Information
- Application Number
- CN202510336409.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2025-07-04
AI Technical Summary
In the prior art, the external capacitor of the bulk acoustic wave resonator requires additional leads and device area, resulting in electrical parasitic phenomena and limiting filter performance.
During the preparation of the resonator, the interdigit capacitance structure is added and arranged outside the resonant area and is directly integrated on the resonator to avoid additional leads and area increases.
Improves the integration of resonator and capacitor devices, avoids electrical parasitics, and improves device performance.
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Figure CN120263139A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of resonators, and more particularly, to a bulk acoustic wave resonator, a preparation method thereof, and a filter. Background Art
[0002] Currently, with the rapid development of wireless communication technologies, there are more and more devices for receiving and transmitting information in higher frequency bands, and the requirements for radio frequency front-end circuits are becoming increasingly stringent. Therefore, the market demand for high-performance filters is increasing. Due to its characteristics such as high quality factor, good out-of-band rejection, and high rectangularity coefficient, bulk acoustic wave filters are gradually becoming the mainstream in the market.
[0003] A bulk acoustic wave filter is composed of multiple resonators cascaded according to a specific circuit. High-performance filters require high-performance resonators. High-performance resonators have a high quality factor, which can enable the filter to have smaller insertion loss and steeper roll-off characteristics, and have more excellent filtering performance. In summary, it is very important to prepare resonators with high stability and excellent performance.
[0004] Due to the limitation of the electromechanical coupling coefficient of the resonator material, the bandwidth of the bulk acoustic wave filter is small. In practical applications, passive devices such as external capacitors or inductors are usually added as matching circuits or to increase the bandwidth of the filter and adjust the filtering characteristics. Surface-mounted capacitor devices are widely used in various electronic products such as mobile phones, computers, tablet computers, televisions, digital cameras, audio equipment, and automotive electronics. However, when used in filters, they need to be connected to the resonator filtering circuit, which requires additional wiring, and their size is relatively large compared to the resonator, resulting in a decrease in filter performance and an inability to reduce the area, greatly limiting the performance of thin film bulk acoustic wave filters. Summary of the Invention
[0005] The purpose of this application is to provide a bulk acoustic wave resonator, a preparation method thereof, and a filter, which can solve the problems of the existing bulk acoustic wave resonator that the external capacitor requires additional leads and the device area is relatively large, thereby avoiding corresponding electrical parasitics, and further improving the device performance.
[0006] The embodiments of this application are implemented as follows:
[0007] In the first aspect of the embodiments of this application, a bulk acoustic wave resonator is provided, including a substrate, and a lower electrode, a piezoelectric layer, and an upper electrode sequentially disposed on the substrate. A groove is provided on the substrate, and the overlapping region of the lower electrode, the piezoelectric layer, and the upper electrode in the stacking direction is used as the resonant region. A interdigital capacitor structure is further provided on the piezoelectric layer, and the interdigital capacitor structure is located outside the resonant region.
[0008] As an implementable manner, the interdigital capacitor structure includes an electrode layer, the electrode layer includes a first electrode and a second electrode, the first electrode includes a plurality of first interdigital bars arranged in parallel and spaced apart from each other and a first main electrode bar connecting the plurality of first interdigital bars, the second electrode includes a plurality of second interdigital bars arranged in parallel and spaced apart from each other and a second main electrode bar connecting the plurality of second interdigital bars, the plurality of first interdigital bars and the plurality of second interdigital bars are alternately and spacedly arranged in sequence, and the first main electrode bar and the second main electrode bar are oppositely arranged and parallel to each other.
[0009] As an implementable manner, a first lead-out portion is provided on the first main electrode bar, a second lead-out portion is provided on the second main electrode bar, and the first lead-out portion and the second lead-out portion do not overlap in the stacking direction.
[0010] As an implementable manner, the interdigital capacitor structure further includes a first dielectric layer, the first dielectric layer is located between the piezoelectric layer and the electrode layer; and / or, the interdigital capacitor structure further includes a second dielectric layer, the second dielectric layer is located on the tops of the first interdigital bars and the second interdigital bars and between the adjacent first interdigital bars and second interdigital bars arranged side by side.
[0011] As an implementable manner, a third electrode is further provided on the piezoelectric layer, the third electrode is located between the adjacent first interdigital bars and second interdigital bars arranged side by side, and the third electrode is used to disconnect or connect to the first electrode.
[0012] As an implementable manner, the third electrode is connected to the first interdigital bar or the first main electrode bar to connect the third electrode to the first electrode.
[0013] As an implementable manner, a seed layer is provided between the substrate and the lower electrode, and the material of the seed layer is the same as the material of the piezoelectric layer.
[0014] As an implementable manner, a passivation layer is provided on the upper electrode.
[0015] In the second aspect of the embodiments of the present application, a method for manufacturing a bulk acoustic wave resonator is provided for manufacturing the above-mentioned bulk acoustic wave resonator, and the method includes:
[0016] Etch a groove in the substrate and deposit a sacrificial layer in the groove;
[0017] Form a lower electrode and a piezoelectric layer in sequence on the substrate deposited with the sacrificial layer;
[0018] An upper electrode and an interdigital capacitor structure are formed on the piezoelectric layer. Among them, an overlapping region of the lower electrode, the piezoelectric layer, and the upper electrode in the stacking direction serves as a resonance region, and the upper electrode is spaced apart from the interdigital capacitor structure;
[0019] Release holes are etched on the upper electrode, and the sacrificial layer is released through the release holes until the groove is exposed, obtaining a bulk acoustic wave resonator.
[0020] In a third aspect of the embodiments of the present application, a filter is provided, including the above-mentioned bulk acoustic wave resonator.
[0021] The beneficial effects of the embodiments of the present application include:
[0022] The bulk acoustic wave resonator includes a substrate, and a lower electrode, a piezoelectric layer, and an upper electrode sequentially arranged on the substrate. A groove is provided on the substrate. An overlapping region of the lower electrode, the piezoelectric layer, and the upper electrode in the stacking direction serves as a resonance region. An interdigital capacitor structure is also provided on the piezoelectric layer, and the interdigital capacitor structure is located outside the resonance region. By adding an interdigital capacitor structure during the preparation process of the resonator, the integration degree of the resonator and the capacitor device is improved. Also, by arranging the interdigital capacitor structure outside the resonance region, the influence on the electrical parasitics of the resonator is avoided. Compared with the prior art in which an external capacitor device is added to the bulk acoustic wave resonator, the direct integration of the interdigital capacitor structure on the resonator provided in the present application can solve the problems of the need for additional leads and a large device area existing in the external capacitor of the bulk acoustic wave resonator in the prior art, thereby avoiding the corresponding electrical parasitics and further improving the device performance. Description of the Drawings
[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0024] Figure 1 It is one of the state diagrams of the bulk acoustic wave resonator provided in the first embodiment of the present application;
[0025] Figure 2 It is the second state diagram of the bulk acoustic wave resonator provided in the first embodiment of the present application;
[0026] Figure 3 It is the third state diagram of the bulk acoustic wave resonator provided in the first embodiment of the present application;
[0027] Figure 4 It is the structural diagram of the bulk acoustic wave resonator provided in the first embodiment of the present application;
[0028] Figure 5 Schematic structural diagram of the bulk acoustic wave resonator provided by the second embodiment of the present application;
[0029] Figure 6 Schematic diagram of the disconnection between the third electrode strip and the first interdigital strip provided by the embodiment of the present application;
[0030] Figure 7 Schematic diagram of the connection between the third electrode strip and the first interdigital strip provided by the embodiment of the present application;
[0031] Figure 8 Schematic diagram of the disconnection between the third electrode strip and the first main electrode strip provided by the embodiment of the present application;
[0032] Figure 9 Schematic diagram of the connection between the third electrode strip and the first main electrode strip provided by the embodiment of the present application.
[0033] Icon: 101 - Substrate; 102 - Sacrificial layer; 103 - Seed layer; 104 - Lower electrode; 105 - Piezoelectric layer; 106a - Upper electrode; 106b - Interdigital capacitor structure; 107 - Passivation layer; 108 - First lead-out part; 109 - Second lead-out part; 110 - First main electrode strip; 111 - First interdigital strip; 112 - Second main electrode strip; 113 - Second interdigital strip; 114 - Second dielectric layer; 115 - Third electrode strip; 116 - Groove. Detailed implementation manners
[0034] The implementation manners described below represent the information necessary for those skilled in the art to practice the described implementation manners and show the best mode of practicing the described implementation manners. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize the applications of these concepts that are not specifically presented herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.
[0035] It should be understood that although terms such as first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present disclosure, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.
[0036] It should be understood that when an element, such as a layer, region, or substrate, is referred to as "on another element" or "extending onto another element", it can be directly on the other element or directly extend onto the other element, or there may also be intervening elements. In contrast, when an element is referred to as "directly on another element" or "directly extending onto another element", there are no intervening elements. Similarly, it should be understood that when an element, such as a layer, region, or substrate, is referred to as "above another element" or "extending above another element", it can be directly above the other element or directly extend above the other element, or there may also be intervening elements. In contrast, when an element is referred to as "directly above another element" or "directly extending above another element", there are no intervening elements. It should also be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as "directly connected" or "directly coupled" to another element, there are no intervening elements.
[0037] Relative terms such as "below", "above", "upper", "lower", "horizontal", or "vertical" may be used herein to describe the relationship of one element, layer, or region to another element, layer, or region, as shown in the figures.
[0038] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" specifies the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups of the foregoing.
[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should also be understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.
[0040] Due to the limitation of the electromechanical coupling coefficient of the resonator material, the bandwidth of the bulk acoustic wave filter is small. Therefore, in practical applications, currently, mainly passive devices such as external capacitors or inductors are added as matching circuits to increase the bandwidth of the filter and adjust the filtering characteristics, etc. Surface mount capacitor devices are widely used in various electronic products such as mobile phones, computers, tablet computers, televisions, digital cameras, audio equipment, automotive electronics, etc. However, when using surface mount capacitor devices in a bulk acoustic wave filter, they need to be connected to the resonator filtering circuit, which requires additional wiring, and their size is relatively large compared to the resonator, resulting in a decrease in filter performance and an inability to reduce the area. Therefore, it greatly limits the performance of the thin film bulk acoustic wave filter.
[0041] To solve the above problems, please refer to Figures 1 to 9 . The present application provides a bulk acoustic wave resonator, its manufacturing method, and a filter. By adding an interdigital capacitor structure 106b during the manufacturing process of the resonator, the integration degree of the resonator and the capacitor device is improved. Also, by disposing the interdigital capacitor structure 106b outside the resonant region, the influence on the electrical parasitics of the resonator is avoided. Compared with the prior art where an external capacitor device is added to the bulk acoustic wave resonator, directly integrating the interdigital capacitor structure 106b on the resonator provided by the present application can solve the problems of the need for additional leads and a relatively large device area existing in the prior art when adding an external capacitor to the bulk acoustic wave resonator, thereby avoiding the corresponding electrical parasitics and further improving the device performance.
[0042] Specifically, as Figures 1 to 5 shown, in the first aspect of the embodiment of the present application, a bulk acoustic wave resonator is provided, which includes a substrate 101, a lower electrode 104, a piezoelectric layer 105, and an upper electrode 106a that are sequentially disposed on the substrate 101. A groove 116 is provided on the substrate 101. The overlapping region of the lower electrode 104, the piezoelectric layer 105, and the upper electrode 106a in the stacking direction serves as the resonant region. An interdigital capacitor structure 106b is further provided on the piezoelectric layer 105, and the interdigital capacitor structure 106b is located outside the resonant region.
[0043] It should be noted that, as Figures 1 to 5 shown, the bulk acoustic wave resonator includes a substrate 101, on which a lower electrode 104, a piezoelectric layer 105, and an upper electrode 106a are sequentially disposed to form a sandwich structure through the lower electrode 104, the piezoelectric layer 105, and the upper electrode 106a. During the operation of the bulk acoustic wave resonator, the two ends of an external signal are respectively connected to the lower electrode 104 and the upper electrode 106a to form an electric field between the lower electrode 104 and the upper electrode 106a, so that the piezoelectric layer 105 is located within the electric field, and under the action of the piezoelectric effect, vibrations are generated to form acoustic waves.
[0044] Among them, the overlapping region of the lower electrode 104, the piezoelectric layer 105, and the upper electrode 106a in the stacking direction serves as the resonant region, enabling sound waves to reflect back and forth within the resonant region. On this basis, a groove 116 is further provided between the upper surface of the substrate 101 and the lower surface of the lower electrode 104. When sound waves propagate at both ends of the sandwich structure, the groove 116 serves as an acoustic reflection cavity, and the air in the groove 116 can reflect the sound waves back into the sandwich structure, so that the energy of the sound waves is as concentrated as possible within the sandwich structure, improving the Q value of the resonator.
[0045] Different from the prior art, the bulk acoustic wave resonator provided in the present application, in addition to having an upper electrode 106a provided on the piezoelectric layer 105, also has an interdigital capacitor structure 106b provided on the piezoelectric layer 105. Moreover, the interdigital capacitor structure 106b is located outside the resonant region. Specifically, the orthographic projection of the interdigital capacitor structure 106b on the substrate 101 is located outside the orthographic projection of the resonant region on the substrate 101. In other words, the interdigital capacitor structure 106b and the upper electrode 106a are arranged at intervals. Or rather, there is no overlapping part between the orthographic projection of the interdigital capacitor structure 106b on the substrate 101 and the orthographic projection of the resonant region on the substrate 101. Exemplarily, as Figures 1 to 5 shown, taking the direction shown in the drawings as an example, in this embodiment, the interdigital capacitor structure 106b is located on the right side of the resonant region.
[0046] Those skilled in the art should understand that during the preparation process of the bulk acoustic wave resonator, when the materials of the upper electrode 106a and the interdigital capacitor structure 106b are the same, in order to further simplify the process steps, the upper electrode 106a and the interdigital capacitor structure 106b can be fabricated simultaneously. Exemplarily, as Figure 2 shown, in this embodiment, after depositing the materials of the electrode and the interdigital capacitor structure 106b on the piezoelectric layer 105, the obtained film layer is patterned through a lithography process, simultaneously generating the design pattern of the upper electrode 106a and the design pattern of the interdigital capacitor structure 106b.
[0047] The bulk acoustic wave resonator provided in the present application improves the integration of the resonator and the capacitor device by adding the interdigital capacitor structure 106b during the preparation process of the resonator, and also avoids affecting the electrical parasitics of the resonator by arranging the interdigital capacitor structure 106b outside the resonant region. Compared with the prior art where an external capacitor device is added to the bulk acoustic wave resonator, directly integrating the interdigital capacitor structure 106b on the resonator provided in the present application can solve the problems of the need for additional leads and a large device area existing in the external capacitor of the bulk acoustic wave resonator in the prior art, thereby avoiding the corresponding electrical parasitics and further improving the device performance.
[0048] As an implementable manner, as Figures 2 to 9As shown, in this embodiment, the interdigital capacitor structure 106b includes an electrode layer, the electrode layer includes a first electrode and a second electrode, the first electrode includes a plurality of first interdigital bars 111 arranged in parallel and spaced apart from each other and a first main bar 110 connecting the plurality of first interdigital bars 111, the second electrode includes a plurality of second interdigital bars 113 arranged in parallel and spaced apart from each other and a second main bar 112 connecting the plurality of second interdigital bars 113, the plurality of first interdigital bars 111 and the plurality of second interdigital bars 113 are alternately and spacedly arranged in sequence, and the first main bar 110 and the second main bar 112 are oppositely arranged and parallel to each other. In this way, the first main bar 110 and the second main bar 112 can be respectively and correspondingly electrically connected to the upper electrode 106a and the lower electrode 104 of the resonator according to the actual required connection relationship, so as to realize the series or parallel connection of the interdigital capacitor structure 106b and the resonator.
[0049] As an implementable manner, as Figure 3 shown, in this embodiment, a first lead-out portion 108 is provided on the first main bar 110, a second lead-out portion 109 is provided on the second main bar 112, and there is no overlapping portion between the first lead-out portion 108 and the second lead-out portion 109 in the stacking direction, so as to avoid interference between the first main bar 110 (i.e., the first electrode) and the second main bar 112 (i.e., the second electrode) of the interdigital capacitor structure 106b. In this way, the first lead-out portion 108 and the second lead-out portion 109 can be respectively and correspondingly electrically connected to the upper electrode 106a and the lower electrode 104 of the resonator according to the actual required connection relationship, so as to realize the series or parallel connection of the interdigital capacitor structure 106b and the resonator.
[0050] In some embodiments, as Figure 4 and Figure 5 shown, since the material of the piezoelectric layer 105 is a dielectric material, therefore, the piezoelectric layer 105 can be directly used as an insulating dielectric (or dielectric layer), so as to prevent conduction between the first interdigital bars 111 of the first electrode and the second interdigital bars 113 of the second electrode through the piezoelectric layer 105; or, in some other embodiments, the interdigital capacitor structure 106b further includes a first dielectric layer, and the first dielectric layer is located between the piezoelectric layer 105 and the electrode layer, that is to say, a separate dielectric layer (i.e., the first dielectric layer) is specially formed on the piezoelectric layer 105 by using an insulating material to prevent conduction between the first interdigital bars 111 of the first electrode and the second interdigital bars 113 of the second electrode through the first dielectric layer; in some other embodiments, as Figure 4As shown, since the multiple first finger-shaped bars 111 of the first electrode and the multiple second finger-shaped bars 113 of the second electrode are arranged alternately and at intervals in sequence, there will inevitably be air in the gaps between the adjacent first finger-shaped bar 111 and the second finger-shaped bar 113. At this time, the air can be directly used as the insulating medium, thereby avoiding conduction between the first finger-shaped bar 111 of the first electrode and the second finger-shaped bar 113 of the second electrode; or, in some other embodiments, as Figure 5 shown, the finger-shaped capacitor structure 106b further includes a second dielectric layer 114. The second dielectric layer 114 is located on the tops of the first finger-shaped bar 111 and the second finger-shaped bar 113 and in the gaps between the adjacent first finger-shaped bar 111 and the second finger-shaped bar 113. Among them, the materials of the first dielectric layer and the second dielectric layer 114 should be insulating materials. Thus, electrical insulation between the first finger-shaped bar 111 and the second finger-shaped bar 113 can also be achieved, and the insulation performance can be improved through the second dielectric layer 114. Those skilled in the art should be able to make reasonable selections and designs according to the actual situation, and no specific limitations are made here.
[0051] As an implementable way, as Figures 3 to 9 shown, in this embodiment, in addition to the upper electrode 106a and the finger-shaped capacitor structure 106b being provided on the piezoelectric layer 105, a third electrode is also provided on the piezoelectric layer 105. The third electrode is located between the adjacent first finger-shaped bar 111 and the second finger-shaped bar 113. The third electrode is used to disconnect or connect with the first electrode to change the physical distance between the adjacent first finger-shaped bar 111 and the second finger-shaped bar 113 through the third electrode, thereby adjusting the capacitance value between the adjacent first finger-shaped bar 111 and the second finger-shaped bar 113, so that the selection range of the capacitance value of the finger-shaped capacitor structure 106b is wider.
[0052] Exemplarily, as Figure 6 shown, the third electrode bar 115 is disconnected from the first electrode. At this time, the physical distance between the first finger-shaped bar 111 and the second finger-shaped bar 113 is the first distance, and the corresponding capacitance value is the first capacitance value; as Figure 7 shown, the third electrode bar 115 is connected to the first electrode. At this time, the third electrode bar 115 and the first finger-shaped bar 111 can be regarded as a whole. The physical distance between the first finger-shaped bar 111 and the second finger-shaped bar 113 is the second distance, and the corresponding capacitance value is the second capacitance value. Since the second distance is less than the first distance, under other unchanged conditions, the second capacitance value is greater than the first capacitance value.
[0053] As an implementable way, as Figures 6 to 9 shown, in this embodiment, the third electrode can be connected to the first finger-shaped bar 111 or the first main electrode bar 110 to connect the third electrode with the first electrode.
[0054] Exemplarily, as Figure 7 shown, the third electrode strip 115 is connected to the first interdigital strip 111. At this time, the physical distance between the first interdigital strip 111 and the second interdigital strip 113 is the third distance, and the corresponding capacitance value is the third capacitance value; as Figure 9 shown, the third electrode strip 115 is connected to the first main electrode strip 110. At this time, the physical distance between the first interdigital strip 111 and the second interdigital strip 113 is the fourth distance, and the corresponding capacitance value is the fourth capacitance value. Since the fourth distance is equal to the third distance, therefore, under the condition that other conditions remain unchanged, the fourth capacitance value is equal to the third capacitance value.
[0055] As an implementable manner, as Figures 1 to 5 shown, a seed layer 103 is provided between the substrate 101 and the lower electrode 104. The material of the seed layer 103 is the same as that of the piezoelectric layer 105, so as to improve the deposition quality of the lower electrode 104 through the seed layer 103, thereby improving the deposition quality of the piezoelectric layer 105, and further improving the Q value of the bulk acoustic wave resonator.
[0056] As an implementable manner, as Figures 3 to 5 shown, a passivation layer 107 is provided on the upper electrode 106a to protect the surface of the bulk acoustic wave resonator away from the substrate 101 through the passivation layer 107.
[0057] As Figures 1 to 4 shown, in the second aspect of the embodiments of the present application, a method for manufacturing a bulk acoustic wave resonator is provided for manufacturing the above-mentioned bulk acoustic wave resonator. The method includes:
[0058] S001, as Figure 1 shown, an etching groove 116 is formed on the substrate 101, and a sacrificial layer 102 is deposited in the groove 116;
[0059] S002, as Figure 1 shown, a lower electrode 104 and a piezoelectric layer 105 are sequentially formed on the substrate 101 deposited with the sacrificial layer 102;
[0060] S003, as Figure 2 and Figure 3 shown, an upper electrode 106a and an interdigital capacitor structure 106b are formed on the piezoelectric layer 105. Among them, the overlapping area of the lower electrode 104, the piezoelectric layer 105 and the upper electrode 106a in the stacking direction is used as the resonant area, and the upper electrode 106a and the interdigital capacitor structure 106b are arranged at intervals;
[0061] S004, as Figure 4 shown, an etching release hole is formed on the upper electrode 106a, and the sacrificial layer 102 is released through the release hole until the groove 116 is exposed to obtain a bulk acoustic wave resonator.
[0062] It should be noted that for the parts where the preparation method of the bulk acoustic wave resonator provided in this embodiment is the same as the specific structure of the bulk acoustic wave resonator in the foregoing text, those skilled in the art can infer the preparation method of the bulk acoustic wave resonator based on the description of the specific structure of the bulk acoustic wave resonator in the foregoing text, and this application will not repeat the description. Since the preparation method of the bulk acoustic wave resonator provided in this embodiment is used to prepare the above-mentioned bulk acoustic wave resonator, therefore, the preparation method of this bulk acoustic wave resonator has the same beneficial effects as the above-mentioned bulk acoustic wave resonator, and will not be elaborated here either.
[0063] In the third aspect of the embodiments of the present application, a filter is provided, and this filter includes the above-mentioned bulk acoustic wave resonator. Since the structure and beneficial effects of the bulk acoustic wave resonator have been described in detail in the foregoing embodiments, they will not be elaborated here.
[0064] The above are only optional embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.
[0065] In addition, it should be noted that for each of the specific technical features described in the above specific implementation manners, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, this application will not separately describe various possible combination manners.
Claims
1. A bulk acoustic wave resonator, characterized in that, It includes a substrate, a lower electrode, a piezoelectric layer, and an upper electrode that are sequentially disposed on the substrate. A groove is provided on the substrate. An overlapping region of the lower electrode, the piezoelectric layer, and the upper electrode in the stacking direction serves as a resonant region. An interdigital capacitor structure is further provided on the piezoelectric layer, and the interdigital capacitor structure is located outside the resonant region.
2. The bulk acoustic wave resonator according to claim 1, characterized in that, The interdigital capacitor structure includes an electrode layer. The electrode layer includes a first electrode and a second electrode. The first electrode includes a plurality of first finger bars that are parallel and spaced apart, and a first main pole bar that connects the plurality of first finger bars. The second electrode includes a plurality of second finger bars that are parallel and spaced apart, and a second main pole bar that connects the plurality of second finger bars. The plurality of first finger bars and the plurality of second finger bars are alternately and spacedly arranged in sequence. The first main pole bar and the second main pole bar are oppositely disposed and parallel to each other.
3. The bulk acoustic wave resonator according to claim 2, characterized in that, A first lead-out portion is provided on the first main pole bar, and a second lead-out portion is provided on the second main pole bar, and the first lead-out portion and the second lead-out portion do not overlap in the stacking direction.
4. The bulk acoustic wave resonator according to claim 2, wherein The interdigital capacitor structure further includes a first dielectric layer, and the first dielectric layer is located between the piezoelectric layer and the electrode layer; and / or, the interdigital capacitor structure further includes a second dielectric layer, and the second dielectric layer is located on the tops of the first finger bars and the second finger bars and between the adjacent first finger bars and second finger bars.
5. The bulk acoustic wave resonator according to claim 2, characterized in that, A third electrode is further provided on the piezoelectric layer, and the third electrode is located between the adjacent first finger bars and second finger bars, and the third electrode is used to disconnect or connect with the first electrode.
6. The bulk acoustic wave resonator according to claim 5, wherein The third electrode is connected to the first finger bar or the first main pole bar to enable the third electrode to be connected to the first electrode.
7. The bulk acoustic wave resonator according to claim 1, wherein A seed layer is provided between the substrate and the lower electrode, and the material of the seed layer is the same as that of the piezoelectric layer.
8. The bulk acoustic wave resonator according to claim 1, characterized in that, A passivation layer is provided on the upper electrode.
9. A method for preparing a bulk acoustic wave resonator, characterized in that, For manufacturing the bulk acoustic wave resonator according to any one of claims 1 to 8, the method includes: Etching a groove on a substrate and depositing a sacrificial layer in the groove; Sequentially forming a lower electrode and a piezoelectric layer on the substrate deposited with the sacrificial layer; Forming an upper electrode and an interdigital capacitor structure on the piezoelectric layer, wherein an overlapping region of the lower electrode, the piezoelectric layer, and the upper electrode in the stacking direction serves as a resonant region, and the upper electrode and the interdigital capacitor structure are spaced apart; Etching a release hole on the upper electrode and releasing the sacrificial layer through the release hole until the groove is exposed to obtain a bulk acoustic wave resonator.
10. A filter, characterized in that, It includes the bulk acoustic wave resonator according to any one of claims 1 to 8.