WO2021077716A1 - 体声波谐振器、滤波器及电子设备 - Google Patents

体声波谐振器、滤波器及电子设备 Download PDF

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Publication number
WO2021077716A1
WO2021077716A1 PCT/CN2020/088666 CN2020088666W WO2021077716A1 WO 2021077716 A1 WO2021077716 A1 WO 2021077716A1 CN 2020088666 W CN2020088666 W CN 2020088666W WO 2021077716 A1 WO2021077716 A1 WO 2021077716A1
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bottom electrode
electrode
resonator
acoustic mirror
resonator according
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PCT/CN2020/088666
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English (en)
French (fr)
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庞慰
杨清瑞
张孟伦
徐洋
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诺思(天津)微系统有限责任公司
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Priority to EP20880234.8A priority Critical patent/EP4050795A4/en
Publication of WO2021077716A1 publication Critical patent/WO2021077716A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H03H9/131—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials consisting of a multilayered structure
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02102—Means for compensation or elimination of undesirable effects of temperature influence
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02125—Means for compensation or elimination of undesirable effects of parasitic elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/173—Air-gaps
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/19—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator consisting of quartz
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/021—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the air-gap type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
    • H03H2003/0407—Temperature coefficient

Definitions

  • the present invention relates to the field of semiconductors, and in particular to a bulk acoustic wave resonator, a filter having the resonator, and an electronic device having the resonator or the filter.
  • FBAR Film Bulk Acoustic Resonator
  • BAW Bulk Acoustic Wave Resonator
  • the main structure of the film bulk acoustic wave resonator is a "sandwich" structure composed of electrode-piezoelectric film-electrode, that is, a layer of piezoelectric material is sandwiched between two metal electrode layers.
  • FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into electrical signal output.
  • the film thickness of the bulk acoustic wave resonator As the working frequency of the filter continues to increase, the film thickness of the bulk acoustic wave resonator, especially the film thickness of the electrode, must be further reduced, resulting in an increase in electrical losses and a decrease in the Q value near the resonator series resonance point and its frequency. Therefore, there is an urgent need for a bulk acoustic wave resonator with simple processing technology and reliable performance with low electrical loss.
  • a bulk acoustic wave resonator including:
  • the piezoelectric layer is arranged between the bottom electrode and the top electrode
  • the bottom electrode includes a first bottom electrode and a second bottom electrode, the first bottom electrode is arranged above the acoustic mirror cavity, and at least a part of the second bottom electrode is arranged in the acoustic mirror cavity to be in contact with the acoustic mirror cavity.
  • the first bottom electrode forms a gap while the second bottom electrode maintains electrical contact with the first bottom electrode.
  • the embodiment of the present invention also relates to a filter including the above-mentioned bulk acoustic wave resonator.
  • the embodiment of the present invention also relates to an electronic device including the above-mentioned filter or the above-mentioned resonator.
  • Fig. 1 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • Fig. 1A is a schematic cross-sectional view taken along A1-A2 in Fig. 1 according to an exemplary embodiment of the present invention
  • FIG. 1B is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to another exemplary embodiment of the present invention, and further shows the heat dissipation path;
  • FIG. 1C is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to another exemplary embodiment of the present invention, and further shows the deformation of the resonator under stress;
  • Fig. 1D is a schematic cross-sectional view taken along A1-A2 in Fig. 1 according to another exemplary embodiment of the present invention
  • Fig. 2 is a schematic cross-sectional view taken along A1-A2 in Fig. 1 according to still another exemplary embodiment of the present invention
  • FIG. 3 is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to another exemplary embodiment of the present invention
  • FIG. 4A is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to yet another exemplary embodiment of the present invention, wherein the first bottom electrode is provided with a through hole;
  • FIG. 4B is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to an exemplary embodiment of the present invention, in which the first bottom electrode and the piezoelectric layer are provided with through holes;
  • FIG. 4C is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to still another exemplary embodiment of the present invention, wherein a through hole is provided outside the first bottom electrode to connect with the release channel of the acoustic mirror cavity, and the first bottom electrode is connected to the release channel of the acoustic mirror cavity.
  • the two bottom electrodes are only arranged in the cavity of the acoustic mirror;
  • 4D is a schematic cross-sectional view taken along A1-A2 in FIG. 1 according to another exemplary embodiment of the present invention, in which the second bottom electrode and the substrate are provided with through holes.
  • Fig. 1 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the reference signs are as follows:
  • Substrate, optional materials are silicon (high-resistance silicon), gallium arsenide, sapphire, quartz, etc.
  • the first bottom electrode, the material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a combination of the above metals or their alloys.
  • Electrode pin the material is the same as the first bottom electrode.
  • the second bottom electrode, the material selection range is the same as that of the first bottom electrode 30, but the specific material is not necessarily the same as that of the first bottom electrode 30.
  • Piezoelectric film layer optional aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or tantalum
  • Materials such as lithium oxide (LiTaO3) may also contain rare earth element doped materials with a certain atomic ratio of the above materials.
  • the first top electrode, the material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a combination of the above metals or their alloys, etc.
  • Electrode pin the same material as the first top electrode.
  • the bottom electrode when the bottom electrode includes a first bottom electrode 30 and a second bottom electrode 31 that are in electrical contact with each other and there is an air gap structure between them, in order to be able to effectively increase the Gap.
  • the second bottom electrode 31 may be partially or completely disposed in the acoustic mirror cavity 20, thereby effectively increasing the above-mentioned gap.
  • the second bottom electrode 31 is laid on the bottom of the cavity-type acoustic mirror 20; and in a further preferred embodiment, the cavity-type acoustic mirror 20 further includes side walls, the The second bottom electrode 31 not only covers the bottom of the cavity-type acoustic mirror 20, but is also further laid on its sidewalls, and at the same time keeps both ends of the second bottom electrode 31 in electrical contact with the first bottom electrode 30, which is equivalent to The second bottom electrode is connected in parallel on the basis of the bottom electrode. Therefore, the electrode loss can be greatly reduced, thereby increasing the Q value of the resonator near the series resonance frequency.
  • the gap between the second bottom electrode and the first bottom electrode can be It has an acoustic isolation effect. Therefore, other properties of the resonator, such as the electromechanical coupling coefficient and the Q value near the parallel resonance frequency, will not be negatively affected.
  • the heat generated in the effective area can be effectively dissipated into the substrate 10 through the second bottom electrode 31. That is, the above structure can effectively increase the contact area between the bottom electrode and the substrate 10 on the one hand. Thereby improving heat dissipation efficiency and power capacity (the arrow in Figure 1B clearly shows the heat dissipation path).
  • the air gap formed by the cavity 20 can be Provide enough space to prevent the bottom electrodes 30 and 31 from being attached. That is to say, the above structure can also effectively increase the air gap 20 between the two layers of lower electrodes, thereby reducing the probability of bending and bonding of the two layers of electrodes under stress, thereby enhancing the performance reliability and process stability of the resonator. In addition, the structure can be made with a simpler release structure, which simplifies the process.
  • the side wall of the acoustic mirror cavity can be processed into a slope shape, as shown in FIG. 1D .
  • the second bottom electrode 31 can be further extended beyond the cavity of the acoustic mirror 20 and kept in electrical contact with the first bottom electrode 30 on the pin side, which can further reduce Low resistance, while ensuring that the electrical connection between the first bottom electrode 30 and the second bottom electrode 31 is more reliable.
  • the side walls are inclined outwardly relative to the bottom, which is more helpful for the second bottom electrode 31 to extend beyond the cavity of the acoustic mirror 20.
  • a through hole 41 can be made on the part of the electrode 30 outside the effective area.
  • the etchant can penetrate the piezoelectric layer 40.
  • the relatively loose microstructure from 41 enters the cavity 20 and gradually decomposes the sacrificial layer material therein.
  • the reaction product can also pass through the piezoelectric layer 40 and be discharged out of the resonator through 41.
  • the through hole 41 can penetrate the electrode layer 30 and the piezoelectric layer 40, which can accelerate the release process of the sacrificial layer and reduce the adverse effect of the etchant on the resonator.
  • a through hole 41 can be made at a position other than the electrode 30, and the through hole is connected with the acoustic mirror cavity through the release channel 21 arranged on the same layer as the acoustic mirror cavity to realize the acoustic mirror cavity Release.
  • the second electrode 31 only covers the acoustic cavity, and does not cover the release channel.
  • the through hole may pass through the substrate 10 and the electrode 31 to form an etchant channel.
  • the air gap constitutes the void layer.
  • the void layer may be a vacuum gap layer, or a void layer filled with another gas medium, in addition to the air gap layer.
  • the mentioned numerical range can also be the median value between the endpoint values or other values, all of which fall within the protection scope of the present invention.
  • the "inside” and “outside” of a component are judged based on which part of the component is closer to the center of the effective area of the resonator in the transverse direction of the resonator, if it is close to the center of the effective area of the resonator , It is the inside, on the contrary, if it is far from the center of the effective area of the resonator, it is the outside.
  • the bulk acoustic wave resonator according to the present invention can be used to form a filter.
  • a bulk acoustic wave resonator including:
  • the piezoelectric layer is arranged between the bottom electrode and the top electrode
  • the bottom electrode includes a first bottom electrode and a second bottom electrode, the first bottom electrode is arranged above the acoustic mirror cavity, and at least a part of the second bottom electrode is arranged in the acoustic mirror cavity to be in contact with the acoustic mirror cavity.
  • the first bottom electrode forms a gap while the second bottom electrode maintains electrical contact with the first bottom electrode.
  • the second bottom electrode covers at least a part of the bottom of the acoustic mirror.
  • the acoustic mirror has a side wall, and the second bottom electrode extends from the bottom to the side wall so as to electrically contact the first bottom electrode.
  • the second bottom electrode is further extended from the side wall to be laid between the substrate and the first bottom electrode.
  • the side wall is perpendicular to the bottom.
  • the side wall is inclined outwardly with respect to the bottom.
  • the overlapping area of the top electrode, the first bottom electrode, the piezoelectric layer and the gap constitutes an effective area of the resonator
  • At least one through hole is provided outside the effective area of the first bottom electrode, and the through hole communicates with the acoustic mirror cavity.
  • the through hole penetrates the first bottom electrode and the piezoelectric layer.
  • the substrate is provided with at least one channel located outside the acoustic mirror cavity, the channel communicates with the acoustic mirror cavity, and the channel extends to the outside of the first bottom electrode in a lateral direction;
  • the resonator further includes at least one through hole disposed outside the first bottom electrode and penetrating the piezoelectric layer, and the through hole is connected to and communicated with the channel outside the first bottom electrode.
  • the second bottom electrode and the substrate are provided with at least one through hole, and the through hole communicates with the acoustic mirror cavity.
  • the upper surface of the gap is higher than the upper surface of the substrate.
  • the upper surface of the gap is flush with the upper surface of the base.
  • a filter comprising the bulk acoustic wave resonator according to any one of 1-12.
  • An electronic device comprising the filter according to 13 or the resonator according to any one of 1-12.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

本发明公开了一种体声波谐振器，包括：基底；声学镜腔体，设置在基底中；底电极；顶电极；压电层，设置在底电极与顶电极之间，其中，所述底电极包括第一底电极和第二底电极，所述第一底电极设置在声学镜腔体上方，至少部分的所述第二底电极设置在声学镜腔体中以与所述第一底电极形成间隙且同时所述第二底电极与所述第一底电极保持电接触。本发明还公开了一种具有上述谐振器的滤波器以及具有该滤波器或谐振器的电子设备。

Description

体声波谐振器、滤波器及电子设备 技术领域
本发明涉及半导体领域，尤其涉及一种体声波谐振器、一种具有该谐振器的滤波器，以及一种具有该谐振器或者该滤波器的电子设备。
背景技术
电子器件作为电子设备的基本元素，已经被广泛应用，其应用范围包括移动电话、汽车、家电设备等。此外，未来即将改变世界的人工智能、物联网、5G通讯等技术仍然需要依靠电子器件作为基础。
薄膜体声波谐振器(Film Bulk Acoustic Resonator，简称FBAR，又称为体声波谐振器，也称BAW)作为压电器件的重要成员正在通信领域发挥着重要作用，特别是FBAR滤波器在射频滤波器领域市场占有份额越来越大，FBAR具有尺寸小、谐振频率高、品质因数高、功率容量大、滚降效应好等优良特性，其滤波器正在逐步取代传统的声表面波(SAW)滤波器和陶瓷滤波器，在无线通信射频领域发挥巨大作用，其高灵敏度的优势也能应用到生物、物理、医学等传感领域。
薄膜体声波谐振器的结构主体为由电极-压电薄膜-电极组成的“三明治”结构，即两层金属电极层之间夹一层压电材料。通过在两电极间输入正弦信号，FBAR利用逆压电效应将输入电信号转换为机械谐振，并且再利用压电效应将机械谐振转换为电信号输出。
随着滤波器工作频率不断提高，体声波谐振器的薄膜厚度尤其是电极的薄膜厚度要进一步减小，从而导致电学损耗增加，谐振器串联谐振点及其频率附近处的Q值降低。因此，亟需一种加工工艺简单、性能可靠的低电损耗体声波谐振器。
发明内容
为缓解或解决现有技术中的上述问题，提出本发明。
根据本发明的实施例的一个方面，提出了一种体声波谐振器，包括：
基底；
声学镜腔体，设置在基底中；
底电极；
顶电极；
压电层，设置在底电极与顶电极之间，
其中，所述底电极包括第一底电极和第二底电极，所述第一底电极设置在声学镜腔体上方，至少部分的所述第二底电极设置在声学镜腔体中以与所述第一底电极形成间隙且同时所述第二底电极与所述第一底电极保持电接触。
本发明的实施例还涉及一种滤波器，包括上述的体声波谐振器。
本发明的实施例也涉及一种电子设备，包括上述的滤波器或者上述的谐振器。
附图说明
以下描述与附图可以更好地帮助理解本发明所公布的各种实施例中的这些和其他特点、优点，图中相同的附图标记始终表示相同的部件，其中：
图1为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图；
图1A为根据本发明的一个示例性实施例的沿图1中的A1-A2截得的剖面示意图；
图1B为根据本发明的另一个示例性实施例的沿图1中的A1-A2截得的剖面示意图，进一步显示了散热路径；
图1C为根据本发明的另一个示例性实施例的沿图1中的A1-A2截得的剖面示意图，进一步显示了谐振器在应力下的形变；
图1D为根据本发明的另一个示例性实施例的沿图1中的A1-A2截得的剖面示意图；
图2为根据本发明的再一个示例性实施例的沿图1中的A1-A2截得的剖面示意图；
图3为根据本发明的又一个示例性实施例的沿图1中的A1-A2截得的剖面示意图；
图4A为根据本发明的又一个示例性实施例的沿图1中的A1-A2截得的剖面示意图，其中第一底电极设有通孔；
图4B为根据本发明的一个示例性实施例的沿图1中的A1-A2截得的剖面示意图，其中第一底电极和压电层设置有贯穿通孔；
图4C为根据本发明的再一个示例性实施例的沿图1中的A1-A2截得的剖面示意图，其中第一底电极外设置有通孔与声学镜空腔的释放通道相连，且第二底电极仅设置在声学镜空腔内；和
图4D为根据本发明的另一个示例性实施例的沿图1中的A1-A2截得的剖面示意图，其中第二底电极和基底设置有贯穿通孔。
具体实施方式
下面通过实施例，并结合附图，对本发明的技术方案作进一步具体的说明。在说明书中，相同或相似的附图标号指示相同或相似的部件。下述参照附图对本发明实施方式的说明旨在对本发明的总体发明构思进行解释，而不应当理解为对本发明的一种限制。
图1为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图。在图1中，各附图标记如下：
10：基底，可选材料为硅(高阻硅)、砷化镓、蓝宝石、石英等。
20：声学镜空腔。
30：第一底电极，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。
36：电极引脚，材料与第一底电极相同。
31：第二底电极，材料选择范围同第一底电极30，但具体材料不一定与第一底电极30相同。
40：压电薄膜层，可选氮化铝(AlN)、氧化锌(ZnO)、锆钛酸铅(PZT)、铌酸锂(LiNbO3)、石英(Quartz)、铌酸钾(KNbO3)或钽酸锂(LiTaO3)等材 料，也可包含上述材料的一定原子比的稀土元素掺杂材料。
50：第一顶电极，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。
56：电极引脚，材料与第一顶电极相同。
21：牺牲层释放通道；
41：牺牲层释放孔；
进一步地，如图1A和图2分别所示，当底电极包括相互电接触的第一底电极30和第二底电极31且两者之间具有空气间隙结构时，为了能够有效地增大该间隙，在本发明中，第二底电极31可以部分或者全部地设置在声学镜腔体20中，从而有效地增大上述间隙。
如图1A所示，在一个优选实施例中，第二底电极31铺设在空腔型声学镜20的底部；而在进一步优选实施例中，空腔型声学镜20还包括侧壁，所述第二底电极31不仅覆盖空腔型声学镜20的底部，还进一步敷设在其侧壁，且同时使第二底电极31的两端与第一底电极30保持电学接触，相当于在第一底电极的基础上并联了第二底电极，因此，可以大幅减小电极损耗，从而提高谐振器在串联谐振频率附近的Q值，同时，由于第二底电极与第一底电极中间存在空隙可以起到声学隔离效果，因此，谐振器的其他性能，如机电耦合系数、并联谐振频率附近的Q值，不会受到任何负面影响。
如图1B所示，当谐振器工作时，有效区域内产生的热量可通过第二底电极31有效散失到基底10中，即上述结构一方面可有效增大底电极与基底10的接触面积，从而提高散热效率和功率容量(图1B中箭头清楚地显示了热量发散路径)。
另一方面，如图1C所示，(虚线分别为顶电极50与第一底电极30的形变)，当谐振器的三明治结构在应力作用下发生弯曲时，借助空腔20形成的空气间隙可提供足够的空间防止底电极30和31发生贴合。即上述结构还可有效增大两层下电极之间的空气间隙20，从而减小两层电极在应力作用下发生弯曲贴合的概率，进而增强了谐振器性能可靠性和工艺稳定性。此外，该结构可采用更为简单的释放结构制成，简化了工艺。
进一步可选地，为了使第二底电极在声学镜空腔的侧壁上具有更好的粘附性和连续性，可以将声学镜空腔的侧壁加工成斜坡状，如图1D所示。
更进一步地，如图2和3所示，还可将第二底电极31进一步延伸至声学镜20的空腔之外并且在引脚侧与第一底电极30保持电接触，这样可进一步减小电阻，同时保证第一底电极30和第二底电极31的电学连接更可靠。其中，图3所示实施例中侧壁相对于底部向外倾斜，从而更有助于第二底电极31延伸至声学镜20的空腔之外。
在本发明中，为了进一步简化加工工艺，可如图4A所示，在电极30位于有效区域之外的部分上制作通孔41，在湿法环境下，刻蚀剂可透过压电层40的较为疏松的微观结构由41进入空腔20并逐步分解掉其中的牺牲层物质，反应生成物也可经41透过压电层40排到谐振器之外。
另外优选地，也可如图4B所示，使通孔41贯穿电极层30和压电层40，这样可加速牺牲层释放过程，减少刻蚀剂对谐振器造成的不利影响。
也可如图4C所示，在电极30以外的位置制作通孔41，通过与声学镜空腔布置在同层的释放通道21，将通孔与声学镜空腔相连通，实现声学镜空腔的释放。其中，第二电极31仅覆盖于声学空腔内，而不覆盖释放通道。
也可如图4D所示，使通孔穿过基底10和电极31形成刻蚀剂通道。
需要说明的是，空气间隙构成空隙层，但是本发明中，空隙层除了可以为空气间隙层之外，还可以是真空间隙层，也可以是填充了其他气体介质的空隙层。
在本发明中，提到的数值范围除了可以为端点值之外，还可以为端点值之间的中值或者其他值，均在本发明的保护范围之内。
在本发明中，一个部件的“内侧”与“外侧”以在谐振器的横向方向上，该部件哪一部分更靠近谐振器的有效区域的中心来进行判断，若靠近谐振器的有效区域的中心，则为内侧，反之，若远离谐振器的有效区域的中心，则为外侧。
如本领域技术人员能够理解的，根据本发明的体声波谐振器可以用于 形成滤波器。
基于以上，本发明提出了如下技术方案：
1、一种体声波谐振器，包括：
基底；
声学镜腔体，设置在基底中；
底电极；
顶电极；
压电层，设置在底电极与顶电极之间，
其中，所述底电极包括第一底电极和第二底电极，所述第一底电极设置在声学镜腔体上方，至少部分的所述第二底电极设置在声学镜腔体中以与所述第一底电极形成间隙且同时所述第二底电极与所述第一底电极保持电接触。
2、根据1所述的谐振器，其中：
所述第二底电极覆盖所述声学镜的底部的至少一部分。
3、根据2所述的谐振器，其中：
所述声学镜具有侧壁，所述第二底电极从底部延伸敷设至侧壁从而电接触所述第一底电极。
4、根据3所述的谐振器，其中：
所述第二底电极进一步从所述侧壁延伸敷设至所述基底和所述第一底电极之间。
5、根据3所述的谐振器，其中：
所述侧壁与所述底部垂直。
6、根据3所述的谐振器，其中：
所述侧壁相对于所述底部向外倾斜。
7、根据1所述的谐振器，其中：
所述顶电极、第一底电极、压电层和间隙的重叠区域构成谐振器的有效区域；
所述第一底电极的有效区域外设置有至少一个通孔，所述通孔与声学镜腔体相通。
8、根据7所述的谐振器，其中：
所述通孔贯穿所述第一底电极和所述压电层。
9、根据1的谐振器，其中：
所述基底中设置有位于声学镜空腔外侧的至少一个通道，所述通道与所述声学镜空腔相通，且所述通道在横向方向上延伸到第一底电极外侧；
所述谐振器还包括设置在所述第一底电极外侧且贯穿所述压电层的至少一个通孔，所述通孔在第一底电极的外侧与所述通道相连而相通。
10、根据1所述的谐振器，其中：
所述第二底电极和所述基底设置有至少一个贯穿通孔，所述贯穿通孔与声学镜腔体相通。
11、根据1所述的谐振器，其中：
所述间隙的上表面高于基底的上表面。
12、根据1所述的谐振器，其中：
所述间隙的上表面与基底的上表面齐平。
13、一种滤波器，包括根据1-12中任一项所述的体声波谐振器。
14、一种电子设备，包括根据13所述的滤波器或者根据1-12中任一项所述的谐振器。
尽管已经示出和描述了本发明的实施例，对于本领域的普通技术人员而言，可以理解在不脱离本发明的原理和精神的情况下可以对这些实施例进行变化，本发明的范围由所附权利要求及其等同物限定。

Claims (14)

  1. 一种体声波谐振器，包括：
    基底；
    声学镜腔体，设置在基底中；
    底电极；
    顶电极；
    压电层，设置在底电极与顶电极之间，
    其中，所述底电极包括第一底电极和第二底电极，所述第一底电极设置在声学镜腔体上方，至少部分的所述第二底电极设置在声学镜腔体中以与所述第一底电极形成间隙且同时所述第二底电极与所述第一底电极保持电接触。
  2. 根据权利要求1所述的谐振器，其中：
    所述第二底电极覆盖所述声学镜的底部的至少一部分。
  3. 根据权利要求2所述的谐振器，其中：
    所述声学镜具有侧壁，所述第二底电极从底部延伸敷设至侧壁从而电接触所述第一底电极。
  4. 根据权利要求3所述的谐振器，其中：
    所述第二底电极进一步从所述侧壁延伸敷设至所述基底和所述第一底电极之间。
  5. 根据权利要求3所述的谐振器，其中：
    所述侧壁与所述底部垂直。
  6. 根据权利要求3所述的谐振器，其中：
    所述侧壁相对于所述底部向外倾斜。
  7. 根据权利要求1所述的谐振器，其中：
    所述顶电极、第一底电极、压电层和间隙的重叠区域构成谐振器的有效区域；
    所述第一底电极的有效区域外设置有至少一个通孔，所述通孔与声学镜腔体相通。
  8. 根据权利要求7所述的谐振器，其中：
    所述通孔贯穿所述第一底电极和所述压电层。
  9. 根据权利要求1所述的谐振器，其中：
    所述基底中设置有位于声学镜空腔外侧的至少一个通道，所述通道与所述声学镜空腔相通，且所述通道在横向方向上延伸到第一底电极外侧；
    所述谐振器还包括设置在所述第一底电极外侧且贯穿所述压电层的至少一个通孔，所述通孔在第一底电极的外侧与所述通道相连而相通。
  10. 根据权利要求1所述的谐振器，其中：
    所述第二电极和所述基底设置有至少一个纵向贯穿通孔，所述纵向贯穿通孔与声学镜腔体相通。
  11. 根据权利要求1所述的谐振器，其中：
    所述间隙的上表面高于基底的上表面。
  12. 根据权利要求1所述的谐振器，其中：
    所述间隙的上表面与基底的上表面齐平。
  13. 一种滤波器，包括根据权利要求1-12中任一项所述的体声波谐振器。
  14. 一种电子设备，包括根据权利要求13所述的滤波器或者根据权利要求1-12中任一项所述的谐振器。
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