Bulk acoustic wave resonators and methods of making, using, and filtering the same
Patent Information
- Application Number
- CN202510377513.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-09-29
AI Technical Summary
目前得到多频滤波器的方法通常是将多个不同频段的滤波器进行并联，从而获得单个滤波器特性相加的多通带频率特性，但这样增加了滤波器结构的复杂性，使得综合特性变差，整机调试困难，也不利于射频前端向微型化、集成化方向的发展
[0040]在实施本申请提供的体声波谐振器技术方案中，本申请的体声波谐振器包括衬底、布拉格反射层、环形第一电极层、环形第一压电层、第二电极层、第二压电层和第三电极层。布拉格反射层、环形第一电极层、第一压电层和第二电极层合围形成空腔。通过上述设置方式，本申请的体声波谐振器，在第一电极层和第二电极层上施加第一电压，能够获得产生第一谐振频率的体声波谐振器，即衬底、布拉格反射层、第一电极层、第一压电层，第二电极层构成一个体声波谐振器。在第二电极层和第三电极层上施加第二电压时，能够获得第二谐振频率的体声波谐振器，即衬底、布拉格反射层、第二电极层、第二压电层和的第三电极层构成另一个体声波谐振器。两个体声波谐振器共用一个第二电极层，通过选择将电压施加到哪两个电极层上，来确定哪个体声波谐振器工作，能够有效减少无线通讯终端所需要的谐振器的数量，在实现多谐振频率的同时，提升体声波谐振器的集成化程度，从而进一步降低无线通讯终端的成本、体积和重量。
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Figure CN122844800A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic technology, specifically to a bulk acoustic wave resonator and its manufacturing method, usage method, and filter. Background Technology
[0002] With the rapid development of mobile communication technology, the application of many radio frequency devices has increased significantly, among which the filter market is expected to experience explosive growth. Currently, the filter devices used in personal mobile terminals (such as mobile phones) are mainly piezoelectric acoustic wave filters. The resonators that make up these filters are mainly: FBAR (thin-film bulk acoustic resonator), SMR (solid-state assembled resonator), and SAW (surface acoustic wave resonator). FBAR and SMR are collectively referred to as BAW (bulk acoustic wave resonator).
[0003] To meet the needs of communication systems for processing signals in different frequency bands, multi-frequency communication systems have emerged, and the implementation of multi-frequency filters, as a key component, has also become a priority. Currently, the common method for obtaining multi-frequency filters is to connect multiple filters from different frequency bands in parallel, thereby obtaining multi-passband frequency characteristics by summing the characteristics of individual filters. However, this increases the complexity of the filter structure, degrades the overall performance, makes system debugging difficult, and hinders the development of RF front-ends towards miniaturization and integration.
[0004] Accordingly, there is a need in the field for a new bulk acoustic resonator scheme to solve the above problems. Summary of the Invention
[0005] In order to overcome the above-mentioned deficiencies, this application is made to solve, or at least partially solve, the technical problem of how to achieve multiple resonant frequencies while improving the integration level of bulk acoustic resonators.
[0006] In a first aspect, a bulk acoustic resonator is provided, comprising:
[0007] Substrate;
[0008] A Bragg reflector layer is disposed on the substrate;
[0009] An annular first electrode layer is disposed on the Bragg reflector layer;
[0010] A ring-shaped first piezoelectric layer is disposed on the first electrode layer;
[0011] The second electrode layer is disposed on the first piezoelectric layer, and together with the Bragg reflector layer, the first electrode layer and the first piezoelectric layer, they form a cavity.
[0012] A second piezoelectric layer is disposed on the second electrode layer;
[0013] The third electrode layer is disposed on the second piezoelectric layer.
[0014] In one technical solution of the above-mentioned bulk acoustic resonator, the bulk acoustic resonator further includes a first temperature compensation layer disposed between the second electrode layer and the second piezoelectric layer.
[0015] In one technical solution of the aforementioned bulk acoustic resonator, the bulk acoustic resonator further includes a second temperature compensation layer disposed between the Bragg reflection layer and the first electrode layer.
[0016] In one technical solution of the aforementioned bulk acoustic resonator, the bulk acoustic resonator further includes a passivation layer disposed on the third electrode layer.
[0017] In one technical solution of the aforementioned bulk acoustic resonator, the Bragg reflector layer is an alternating stacked structure of low acoustic impedance layer and high acoustic impedance layer.
[0018] In a second aspect, a method for manufacturing a bulk acoustic resonator is provided, comprising:
[0019] A Bragg reflector layer is formed on the substrate;
[0020] A columnar sacrificial layer is formed on the Bragg reflector layer;
[0021] A first electrode layer is formed on the Bragg reflector layer, surrounding the sacrificial layer;
[0022] A first piezoelectric layer is formed on the first electrode layer surrounding the sacrificial layer;
[0023] A second electrode layer is formed on the first piezoelectric layer, covering the first piezoelectric layer and the sacrificial layer;
[0024] A second piezoelectric layer is formed on the second electrode layer;
[0025] A third electrode layer is formed on the second piezoelectric layer;
[0026] The sacrificial layer is removed to form a cavity surrounded by the Bragg reflector layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer.
[0027] In one embodiment of the above-mentioned method for manufacturing a bulk acoustic resonator, before forming the second piezoelectric layer, the method further includes: forming a first temperature compensation layer on the second electrode layer, wherein the second piezoelectric layer is formed on the first temperature compensation layer.
[0028] In one embodiment of the above-mentioned method for manufacturing a bulk acoustic resonator, before forming the first electrode layer, the method further includes:
[0029] A second temperature compensation layer is formed on the Bragg reflector layer, wherein the first electrode layer is formed on the second temperature compensation layer.
[0030] In one technical solution of the above-mentioned method for manufacturing a bulk acoustic resonator, the method further includes:
[0031] A passivation layer is formed on the third electrode layer.
[0032] In one technical solution of the above-mentioned method for manufacturing a bulk acoustic resonator, removing the sacrificial layer includes:
[0033] A through hole is formed, penetrating the second electrode layer from the surface of the third electrode layer to expose the sacrificial layer;
[0034] The sacrificial layer is etched to form the cavity.
[0035] In a third aspect, a method for using a bulk acoustic resonator according to the above-described bulk acoustic resonator technology is provided, comprising:
[0036] In response to the application of a first voltage on the first electrode layer and the second electrode layer, a bulk acoustic wave with a first resonant frequency is generated;
[0037] In response to the application of a second voltage on the third electrode layer and the second electrode layer, a bulk acoustic wave with a second resonant frequency is generated.
[0038] In a fourth aspect, a filter is provided, including the bulk acoustic resonator of the above-mentioned bulk acoustic resonator technology.
[0039] The above-described technical solutions of this application have at least one or more of the following beneficial effects:
[0040] In implementing the bulk acoustic wave resonator technology solution provided in this application, the bulk acoustic wave resonator of this application includes a substrate, a Bragg reflector layer, an annular first electrode layer, an annular first piezoelectric layer, a second electrode layer, a second piezoelectric layer, and a third electrode layer. The Bragg reflector layer, the annular first electrode layer, the first piezoelectric layer, and the second electrode layer together form a cavity. With the above arrangement, the bulk acoustic wave resonator of this application, when a first voltage is applied to the first electrode layer and the second electrode layer, can obtain a bulk acoustic wave resonator that generates a first resonant frequency, i.e., the substrate, the Bragg reflector layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer constitute one bulk acoustic wave resonator. When a second voltage is applied to the second electrode layer and the third electrode layer, a bulk acoustic wave resonator with a second resonant frequency can be obtained, i.e., the substrate, the Bragg reflector layer, the second electrode layer, the second piezoelectric layer, and the third electrode layer constitute another bulk acoustic wave resonator. Two bulk acoustic wave resonators share a second electrode layer. By selecting which two electrode layers to apply voltage to, the operation of the bulk acoustic wave resonator can be determined. This can effectively reduce the number of resonators required for wireless communication terminals. While achieving multiple resonant frequencies, it can also improve the integration level of bulk acoustic wave resonators, thereby further reducing the cost, size, and weight of wireless communication terminals. Attached Figure Description
[0041] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Wherein:
[0042] Figure 1 This is a schematic diagram of the main components of a bulk acoustic resonator according to an embodiment of this application;
[0043] Figure 2 This is a schematic diagram of the principle of a surface acoustic wave resonator;
[0044] Figure 3 This is a schematic diagram of the main components of a thin-film bulk acoustic resonator.
[0045] Figure 4 This is a schematic diagram of the main components of a solid-state assembled resonator;
[0046] Figure 5 This is a schematic flowchart of the main steps of a method for manufacturing a bulk acoustic resonator according to an embodiment of this application;
[0047] Figures 6-21 These are the structural cross-sectional diagrams corresponding to the main steps;
[0048] Figure 22 This is a schematic flowchart of the main steps of using a bulk acoustic resonator according to an embodiment of this application.
[0049] Figure label:
[0050] 101: Substrate; 102: Low acoustic impedance layer; 103: High acoustic impedance layer; 104: Sacrificial layer; 105: First electrode layer; 106: First piezoelectric layer; 107: Second electrode layer; 108: Second piezoelectric layer; 109: Third electrode layer; 110: First temperature compensation layer; 111: Second temperature compensation layer; 112: Passivation layer; 113: Cavity. Detailed Implementation
[0051] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.
[0052] Here we will first explain some of the terms used in this application.
[0053] FBAR: Film Bulk Acoustic Resonator
[0054] SMR: Solidly Mounted Resonator
[0055] BAW: Bulk Acoustic Wave Resonator
[0056] SAW: Surface Acoustic Wave, surface acoustic wave resonator
[0057] With the rapid development of mobile communication technology, the application of many radio frequency devices has increased significantly, among which the filter market has experienced explosive growth. Currently, the filtering devices used in personal mobile terminals (such as mobile phones) are mainly piezoelectric acoustic wave (BAW) filters. The resonators constituting these filters are primarily: FBAR (Thin Film Bulk Acoustic Resonator), SMR (Solid State Mesh Resonator), and SAW (Surface Acoustic Wave Resonator), with FBAR and SMR collectively referred to as BAW. The working principle of a SAW resonator is to convert electrical signals into sound waves propagating on the surface of a piezoelectric layer through interdigital transducers. For details, please refer to the appendix. Figure 1 ,like Figure 1As shown, its resonant frequency is determined by the spacing between the IDT (Interdigital Transducers) electrodes, i.e., fp = v / p, where p is the spacing between the IDT electrodes and v is the velocity. The working principle of a BAW resonator is to convert an electrical signal into a bulk acoustic wave propagating along the thickness of the piezoelectric layer. The resonant frequency is determined by the thickness of the piezoelectric layer, i.e., fp = v / 2t, where t is the thickness of the piezoelectric film and v is the speed of sound. The electrode thickness also has some influence on the bulk acoustic wave resonator. Two commonly used structures of BAW resonators, FBAR and SMR, can be found in the attached diagram. Figure 2 and attached Figure 3 ,like Figure 2 and Figure 3 As shown, the difference between FBAR and SMR lies in the fact that FBAR utilizes the near-zero acoustic impedance of air to achieve near total internal reflection of the interface sound wave, while SMR is based on a Bragg reflector layer composed of alternating high and low acoustic impedance layers to achieve near total internal reflection. Compared to SAW, BAW has advantages such as lower insertion loss, higher Q value, steeper roll-off characteristics, and larger power capacity, but SAW is cheaper and has the advantage of impedance transformation.
[0058] To meet the needs of communication systems for processing signals in different frequency bands, multi-frequency communication systems have emerged, and the implementation of multi-frequency filters, as a key component, has also become a priority. Currently, the common method for obtaining multi-frequency filters is to connect multiple filters of different frequency bands in parallel, thereby obtaining multi-passband frequency characteristics by summing the characteristics of individual filters. However, this increases the complexity of the filter structure, degrades the overall performance, makes system debugging difficult, and hinders the development of RF front-ends towards miniaturization and integration. To address these problems, this invention proposes a novel bulk acoustic resonator.
[0059] See appendix Figure 4 , Figure 4 This is a schematic diagram of the main structural components of a bulk acoustic resonator according to an embodiment of this application. Figure 4 As shown, the bulk acoustic wave resonator in this embodiment mainly includes a substrate 101, a Bragg reflector layer, an annular first electrode layer 105, an annular first piezoelectric layer 106, a second electrode layer 107, a second piezoelectric layer 108, and a third electrode layer 109.
[0060] In this embodiment, a Bragg reflector layer is disposed on a substrate 101; a first electrode layer 105 is disposed on the Bragg reflector layer; a first piezoelectric layer 106 is disposed on the first electrode layer 105; a second electrode layer 107 is disposed on the first piezoelectric layer 106, forming a cavity 113 together with the Bragg reflector layer, the first electrode layer 105, and the first piezoelectric layer 106; a second piezoelectric layer 108 is disposed on the second electrode layer 107; and a third electrode layer 109 is disposed on the second piezoelectric layer 108.
[0061] In one embodiment, the substrate 101 can be made of materials such as ceramic, glass, silicon (Si), gallium arsenide (GaAs), or sapphire. The thickness of the substrate 101 can be 400-600 μm.
[0062] In one embodiment, the material of the first electrode layer 105 can be selected from platinum (Pt), aluminum (Al), molybdenum (Mo), and the thickness can be 0.15-0.25 μm.
[0063] In one embodiment, the material of the first piezoelectric layer 106 may be one of aluminum nitride (AlN), zinc oxide (ZnO), or lead zirconate titanate (PZT), and the thickness of the first piezoelectric layer 106 may be 0.5-1.5 μm.
[0064] In one embodiment, the material of the second electrode layer 107 can be selected from platinum (Pt), aluminum (Al), molybdenum (Mo), and the thickness can be 0.15-0.25 μm.
[0065] In one embodiment, the material of the second piezoelectric layer 108 may be one of aluminum nitride (AlN), ZnO (zinc oxide), or lead zirconate titanate (PZT), and the thickness of the second piezoelectric layer 108 may be 0.5-1.5 μm.
[0066] In one embodiment, the height of the cavity 113 (i.e., perpendicular to the substrate direction) can be 0.65-1.75 μm.
[0067] In one embodiment, the material of the third electrode layer 109 can be selected from platinum (Pt), aluminum (Al), molybdenum (Mo), and the thickness can be 0.15-0.25 μm.
[0068] The bulk acoustic wave (BAW) resonator of this embodiment, when a first voltage is applied to the first electrode layer 105 and the second electrode layer 107, can obtain a BAW resonator that generates a first resonant frequency. Specifically, the substrate 101, Bragg reflector layer, first electrode layer 105, and first piezoelectric layer 106, with the second electrode layer 107 forming one BAW resonator, is an SMR type resonator. When a second voltage is applied to the second electrode layer 107 and the third electrode layer 109, a BAW resonator with a second resonant frequency can be obtained. Specifically, the substrate 101, Bragg reflector layer, second electrode layer 107, second piezoelectric layer 108, and third electrode layer 109 form another BAW resonator, which is an FBAR type resonator. The two BAW resonators share a single second electrode layer 107. By selecting which two electrode layers to apply voltage to, the operating BAW resonator can be determined, effectively reducing the number of resonators required in the wireless communication terminal. While achieving multiple resonant frequencies, the integration level of the BAW resonator is improved, thereby further reducing the cost, size, and weight of the wireless communication terminal.
[0069] In one embodiment of this application, the Bragg reflector layer can be an alternating stacked structure of a low acoustic impedance layer 102 and a high acoustic impedance layer 103. The alternating stacked structure includes at least one pair of low acoustic impedance layers 102 and high acoustic impedance layers 103. Figure 4 (The image shows two pairs).
[0070] In one embodiment of this application, the thickness of a low acoustic impedance layer 102 can be 0.6-1 μm, and the material of the low acoustic impedance layer 102 can be SiO2. The thickness of a high acoustic impedance layer 103 on top of the low acoustic impedance layer 102 can be 0.3-0.6 μm, and the material can be tungsten (W). The thickness of a low acoustic impedance layer 102 on top of the high acoustic impedance layer 103 can be 0.6-1 μm, and the material can be SiO2. The thickness of a high acoustic impedance layer 103 on top of the low acoustic impedance layer 102 can be 0.3-0.6 μm, and the material can be tungsten (W). The alternating stacked structure of two pairs of low acoustic impedance layers 102 and high acoustic impedance layers 103 constitutes a Bragg reflector layer.
[0071] In one embodiment of this application, the bulk acoustic resonator may further include a first temperature compensation layer 110, which may be disposed between the second electrode layer 107 and the second piezoelectric layer 108, such as... Figure 18 As shown. The first temperature compensation layer 110 can be used to compensate for the frequency shift of the bulk acoustic resonator caused by temperature changes. The material of the first temperature compensation layer 110 can be silicon dioxide (SiO2), and the thickness of the first temperature compensation layer 110 can be 0.15-0.25 μm.
[0072] In one embodiment of this application, the bulk acoustic resonator may further include a second temperature compensation layer 111, which is disposed between the Bragg radiation layer and the first electrode layer 105, such as... Figure 20 As shown. The second temperature compensation layer 111 can be used to compensate for the frequency shift of the bulk acoustic resonator caused by temperature changes. The material of the second temperature compensation layer 111 can be silicon dioxide (SiO2), and the thickness of the second temperature compensation layer 111 can be 0.25-0.35 μm.
[0073] It should be noted that, although Figure 20 The diagram shows a structure that simultaneously has a second temperature compensation layer 111 and a first temperature compensation layer 110, but those skilled in the art will understand that the second temperature compensation layer and the first temperature compensation layer 110 can each exist independently.
[0074] In one embodiment of this application, the bulk acoustic resonator may further include a passivation layer 112, which is disposed on the third electrode layer 109, such as... Figure 19 As shown.
[0075] In one embodiment, the material of the passivation layer 112 may be the same as that of the first piezoelectric layer 106 and the second piezoelectric layer. The passivation layer 112 is used to protect the structure of the bulk acoustic resonator from moisture, corrosion, contaminants, debris, etc.
[0076] In one implementation, such as Figure 21 As shown, a second temperature compensation layer 111 can be provided between the Bragg reflection layer and the first electrode layer 105, and a passivation layer 112 can be provided on the third electrode layer 109.
[0077] Furthermore, this application also provides a method for manufacturing a bulk acoustic resonator.
[0078] See appendix Figure 5 , Figures 6-21 , Figure 5 This is a schematic flowchart of the main steps of a method for manufacturing a bulk acoustic resonator according to an embodiment of this application. Figures 6-21 This is the corresponding structural cross-sectional view.
[0079] like Figure 5 As shown, the manufacturing method of the bulk acoustic resonator in this application embodiment mainly includes the following steps S201 to S208:
[0080] Step S201: Form a Bragg reflector layer on substrate 101.
[0081] In this embodiment, the Bragg reflector layer can be an alternating stacked structure of a low acoustic impedance layer 102 and a high acoustic impedance layer 103.
[0082] In one embodiment, the substrate 101 can be made of materials such as ceramic, glass, silicon (Si), gallium arsenide (GaAs), or sapphire. The thickness of the substrate 101 can be 400-600 μm.
[0083] In one embodiment, the Bragg reflector layer can be an alternating stacked structure of two pairs of low acoustic impedance layers 102 and high acoustic impedance layers 103. For example... Figures 6-9 As shown, a low acoustic impedance layer 102 with a thickness of 0.6-1 μm can be deposited on the substrate 101. The material of the low acoustic impedance layer 102 can be SiO2. A high acoustic impedance layer 103 with a thickness of 0.3-0.6 μm is then deposited on the low acoustic impedance layer 102. The material can be tungsten (W). Further, a low acoustic impedance layer 102 with a thickness of 0.6-1 μm can be deposited on the high acoustic impedance layer 103. Again, a high acoustic impedance layer 103 with a thickness of 0.3-0.6 μm can be deposited on the low acoustic impedance layer 102. The alternating stacked structure of the two pairs of low acoustic impedance layers 102 and high acoustic impedance layers 103 constitutes a Bragg reflector layer.
[0084] Step S202: Form a columnar sacrificial layer 104 on the Bragg reflector layer.
[0085] In this embodiment, the material of the sacrificial layer 104 can be PSG (phosphorus silicon glass) (P (phosphorus) doped SiO2) or one of SiO2, polycrystalline silicon, metal and polymer.
[0086] The sacrificial layer 104 material can be deposited on the Bragg reflector layer using sputtering, CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), spin coating, or other similar processes. Figure 10 As shown.
[0087] In one embodiment, a sacrificial layer 104 material can be deposited on the Bragg reflector layer to form a sacrificial material layer, and the sacrificial material layer can be patterned to form a columnar sacrificial layer 104, such as... Figure 11 As shown.
[0088] In one embodiment, the thickness of the columnar sacrificial layer 104 can be 0.65-1.75 μm.
[0089] Step S203: Form a first electrode layer 105 around the sacrificial layer 104 on the Bragg reflector layer.
[0090] In this embodiment, the first electrode layer 105 can be formed by magnetron sputtering. The material of the first electrode layer 105 can be selected from platinum (Pt), aluminum (Al), and molybdenum (Mo), and the thickness can be 0.15-0.25 μm.
[0091] In one embodiment, a first electrode material layer can be deposited by masking the sacrificial layer 104, thereby forming an annular first electrode layer 105 surrounding the sacrificial layer 104, such as... Figure 12 As shown.
[0092] Step S204: A first piezoelectric layer 106 is formed on the first electrode layer 105 surrounding the sacrificial layer 104.
[0093] In this embodiment, the material of the first piezoelectric layer 106 can be one of aluminum nitride (AlN), ZnO (zinc oxide), or lead zirconate titanate (PZT), and the thickness of the first piezoelectric layer 106 can be 0.5-1.5 μm.
[0094] In one embodiment, the sacrificial layer 104 can still be masked while a first piezoelectric material layer is deposited, thereby forming an annular first piezoelectric layer 106 surrounding the sacrificial layer 104, such as... Figure 13 As shown.
[0095] Step S205: A second electrode layer 107 is formed on the first piezoelectric layer 106, covering the first piezoelectric layer 106 and the sacrificial layer 104, as shown below. Figure 14 As shown.
[0096] In this embodiment, the material of the second electrode layer 107 can be selected from platinum (Pt), aluminum (Al), and molybdenum (Mo), and the thickness can be 0.15-0.25 μm.
[0097] In one embodiment, the second electrode layer 107 can be formed by magnetron sputtering.
[0098] Step S206: Form a second piezoelectric layer 108 on the second electrode layer 107, such as Figure 15 As shown.
[0099] In this embodiment, the material of the second piezoelectric layer 108 can be one of aluminum nitride (AlN), ZnO (zinc oxide), or lead zirconate titanate (PZT), and the thickness of the second piezoelectric layer 108 can be 0.5-1.5 μm.
[0100] Step S207: Form a third electrode layer 109 on the second piezoelectric layer 108, such as Figure 16 As shown.
[0101] In this embodiment, the material of the third electrode layer 109 can be selected from platinum (Pt), aluminum (Al), and molybdenum (Mo), and the thickness can be 0.15-0.25 μm.
[0102] In one embodiment, the third electrode layer 109 can be formed by magnetron sputtering.
[0103] Step S208: Remove the sacrificial layer 104 to form a cavity 113 surrounded by the Bragg reflector layer, the first electrode layer 105, the first piezoelectric layer 106, and the second electrode layer 107, as shown. Figure 17 As shown.
[0104] In this embodiment, a through hole can be formed to penetrate the second electrode layer 107 from the surface of the third electrode layer 109, exposing the sacrificial layer 104, and the sacrificial layer 104 can be etched to form a cavity 113, that is, the space left after the sacrificial layer is removed.
[0105] In one embodiment, prior to step S206, the method for manufacturing the bulk acoustic resonator of this application may further include the following step S209.
[0106] Step S209: Form a first temperature compensation layer 110 on the second electrode layer 107, such as Figure 18 As shown.
[0107] In this embodiment, a first temperature compensation layer 110 can be formed on the second electrode layer 107, and a second piezoelectric layer 108 can be formed on the first temperature compensation layer 110. The material of the first temperature compensation layer 110 can be silicon dioxide (SiO2), and the thickness of the first temperature compensation layer 110 can be 0.15-0.25 μm.
[0108] In one embodiment, prior to step S203, the method for manufacturing the bulk acoustic resonator of this application may further include the following step S210.
[0109] Step S210: Form a second temperature compensation layer 111 on the Bragg reflector layer, such as Figure 20 As shown.
[0110] In this embodiment, a second temperature compensation layer 111 can be formed on the Bragg reflector layer, and a first electrode layer 105 can be formed on the second temperature compensation layer 111. The material of the second temperature compensation layer 111 can be silicon dioxide (SiO2), and the thickness of the second temperature compensation layer 111 can be 0.25-0.35 μm.
[0111] In one embodiment, the method for manufacturing a bulk acoustic resonator according to this application may further include the following step S211.
[0112] Step S211: Form a passivation layer 112 on the third electrode layer 109, such as Figure 19 As shown.
[0113] In this embodiment, the thickness of the passivation layer 112 can be 0.25-0.35 μm. The passivation layer 112 can protect the bulk acoustic wave resonator from the effects of moisture, corrosion, contaminants, debris, etc. The material of the passivation layer 112 can be the same as the material of the first piezoelectric layer 106 and the second piezoelectric layer 108.
[0114] like Figure 21 As shown, a second temperature compensation layer 111 can be formed between the Bragg reflector layer and the first electrode layer 105, and a passivation layer 112 can be formed on the third electrode layer 109.
[0115] Furthermore, this application also provides a method of using a bulk acoustic resonator.
[0116] See appendix Figure 22 , Figure 22 This is a schematic flowchart illustrating the main steps of using a bulk acoustic resonator according to an embodiment of this application. Figure 22 As shown, the method of using the bulk acoustic resonator of this application mainly includes the following steps S401 and S402.
[0117] Step S401: In response to applying a first voltage to the first electrode layer 105 and the second electrode layer 107, a bulk acoustic wave with a first resonant frequency is generated.
[0118] Step S402: In response to applying a second voltage to the third electrode layer 109 and the second electrode layer 107, a bulk acoustic wave with a second resonant frequency is generated.
[0119] Furthermore, this application also provides a filter.
[0120] In one embodiment of the filter according to this application, the filter may include the bulk acoustic resonator in the above-described bulk acoustic resonator embodiment.
[0121] In one implementation, the filter can be a multi-frequency filter. A multi-frequency filter may include N bulk acoustic resonators connected in series and / or parallel. Each bulk acoustic resonator is capable of generating bulk acoustic waves with two resonant frequencies, and the multi-frequency bulk acoustic resonator is capable of generating 2N bulk acoustic waves with resonant frequencies. Here, N is an integer greater than or equal to 2.
[0122] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These adjusted solutions are equivalent to the technical solutions described in this application and therefore will also fall within the protection scope of this application.
[0123] The technical solution of this application has been described above with reference to one embodiment shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.
Claims
1. A bulk acoustic resonator, characterized in that, include: Substrate; A Bragg reflector layer is disposed on the substrate; An annular first electrode layer is disposed on the Bragg reflector layer; A ring-shaped first piezoelectric layer is disposed on the first electrode layer; The second electrode layer is disposed on the first piezoelectric layer, and together with the Bragg reflector layer, the first electrode layer and the first piezoelectric layer, they form a cavity. A second piezoelectric layer is disposed on the second electrode layer; The third electrode layer is disposed on the second piezoelectric layer.
2. The bulk acoustic resonator according to claim 1, characterized in that, The bulk acoustic resonator further includes a first temperature compensation layer disposed between the second electrode layer and the second piezoelectric layer.
3. The bulk acoustic resonator according to claim 1 or 2, characterized in that, The bulk acoustic resonator further includes a second temperature compensation layer disposed between the Bragg reflection layer and the first electrode layer.
4. The bulk acoustic resonator according to any one of claims 1-3, characterized in that, The bulk acoustic resonator also includes a passivation layer disposed on the third electrode layer.
5. The bulk acoustic resonator according to any one of claims 1-4, characterized in that, The Bragg reflector layer is a stacked structure of alternating low acoustic impedance layers and high acoustic impedance layers.
6. A method for manufacturing a bulk acoustic resonator, characterized in that, include: A Bragg reflector layer is formed on the substrate; A columnar sacrificial layer is formed on the Bragg reflector layer; A first electrode layer is formed on the Bragg reflector layer, surrounding the sacrificial layer; A first piezoelectric layer is formed on the first electrode layer surrounding the sacrificial layer; A second electrode layer is formed on the first piezoelectric layer, covering the first piezoelectric layer and the sacrificial layer; A second piezoelectric layer is formed on the second electrode layer; A third electrode layer is formed on the second piezoelectric layer; The sacrificial layer is removed to form a cavity surrounded by the Bragg reflector layer, the first electrode layer, the first piezoelectric layer, and the second electrode layer.
7. The method for manufacturing a bulk acoustic resonator according to claim 6, characterized in that, Before forming the second piezoelectric layer, the method further includes forming a first temperature compensation layer on the second electrode layer, wherein the second piezoelectric layer is formed on the first temperature compensation layer.
8. The method for manufacturing a bulk acoustic resonator according to claim 6 or 7, characterized in that, Before forming the first electrode layer, the method further includes: A second temperature compensation layer is formed on the Bragg reflector layer, wherein the first electrode layer is formed on the second temperature compensation layer.
9. The method for manufacturing a bulk acoustic resonator according to any one of claims 6-8, characterized in that, The method further includes: A passivation layer is formed on the third electrode layer.
10. The method for manufacturing a bulk acoustic resonator according to claim 6, characterized in that, The removal of the sacrificial layer includes: A through hole is formed, penetrating the second electrode layer from the surface of the third electrode layer to expose the sacrificial layer; The sacrificial layer is etched to form the cavity.
11. A method of using a bulk acoustic resonator according to any one of claims 1-5, characterized in that, include: In response to the application of a first voltage on the first electrode layer and the second electrode layer, a bulk acoustic wave with a first resonant frequency is generated; In response to the application of a second voltage on the third electrode layer and the second electrode layer, a bulk acoustic wave with a second resonant frequency is generated.
12. A filter, characterized in that, Includes a bulk acoustic resonator according to any one of claims 1-5.