WO2021077713A1 - 体声波谐振器及其制造方法、滤波器和电子设备 - Google Patents

体声波谐振器及其制造方法、滤波器和电子设备 Download PDF

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WO2021077713A1
WO2021077713A1 PCT/CN2020/088663 CN2020088663W WO2021077713A1 WO 2021077713 A1 WO2021077713 A1 WO 2021077713A1 CN 2020088663 W CN2020088663 W CN 2020088663W WO 2021077713 A1 WO2021077713 A1 WO 2021077713A1
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electrode
channel
resonator
gap
layer
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PCT/CN2020/088663
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English (en)
French (fr)
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庞慰
徐洋
郝龙
张孟伦
杨清瑞
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诺思(天津)微系统有限责任公司
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Priority to EP20880311.4A priority Critical patent/EP4050796A4/en
Publication of WO2021077713A1 publication Critical patent/WO2021077713A1/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
    • H03H9/15—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
    • 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
    • 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
    • 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
    • H03H9/02—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
    • 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
    • H03H2003/023—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 membrane type

Definitions

  • the embodiments of the present invention relate to the field of semiconductors, and in particular to a bulk acoustic wave resonator and a manufacturing method thereof, 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
  • SAW surface acoustic wave
  • 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.
  • a bulk acoustic wave resonator including:
  • the piezoelectric layer is arranged between the bottom electrode and the top electrode
  • the overlapping area of the top electrode, the bottom electrode, the acoustic mirror, and the piezoelectric layer in the thickness direction of the resonator defines the effective area of the resonator
  • the bottom electrode and/or the top electrode are gap electrodes.
  • the gap electrode has a first electrode and a second electrode.
  • the first electrode is attached to the piezoelectric layer.
  • a gap layer is defined between the first electrode and the second electrode.
  • the layer is located between the first electrode and the second electrode in the height direction of the resonator;
  • the gap electrode is provided with at least one release channel for forming the gap layer, the release channel is in communication with the gap layer, the release channel includes an electrode channel portion, the electrode channel portion is provided in an ineffective area of the electrode in.
  • the present invention also provides a method for manufacturing the above-mentioned bulk acoustic wave resonator, which includes the following steps:
  • the sacrificial layer material is etched with an etchant to generate the gap layer.
  • 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. 1A is a top view of the process structure of a bulk acoustic wave resonator with an air gap on the top electrode according to an exemplary embodiment of the present invention
  • FIG. 1B is a cross-sectional view of the process structure of a bulk wave resonator with an air gap on the top electrode, which is generated along the line A1-A2 in FIG. 1A, according to an exemplary embodiment of the present invention.
  • the arrangement is not shown Sacrificial hole in the top electrode;
  • FIG. 1C is a cross-sectional view of a bulk wave resonator with an air gap on the top electrode, which is generated by cutting along the line A1-A2 in FIG. 1A, according to an exemplary embodiment of the present invention.
  • the etchant enters the air gap from the outside through the channel.
  • Figure 1C the sacrificial hole at the non-lead end of the top electrode is not shown;
  • FIG. 2A is a cross-sectional view of the process structure of a bulk acoustic wave resonator with an air gap at the bottom electrode according to an exemplary embodiment of the present invention
  • 2B is a cross-sectional view of the process structure of a bulk acoustic wave resonator with an air gap at the bottom electrode according to an exemplary embodiment of the present invention
  • 3A is a top view of a bulk acoustic wave resonator with an air gap at the bottom electrode according to an exemplary embodiment of the present invention
  • 3B is a cross-sectional view of the process structure of a bulk acoustic wave resonator with an air gap at the bottom electrode according to an exemplary embodiment of the present invention.
  • FIG. 4 is a cross-sectional view of the process structure of a bulk acoustic wave resonator with an air gap at the bottom electrode according to an exemplary embodiment of the present invention.
  • Substrate, optional materials are silicon (high-resistance silicon), gallium arsenide, sapphire, quartz, etc.
  • Acoustic mirror which is cavity 20 in Fig. 1B. Bragg reflector and other equivalent forms can also be used. However, when the bottom electrode is provided with an etching channel, the acoustic mirror has a cavity structure.
  • 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 (LiNbO 3 ), quartz (Quartz), potassium niobate (KNbO 3 ) Or lithium tantalate (LiTaO 3 ) and other materials 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.
  • 60 An air gap located in the top electrode, between the first top electrode 50 and the second top electrode 70.
  • the second top electrode, the material selection range is the same as that of the first top electrode 50, but the specific material is not necessarily the same as the first top electrode 50.
  • a sacrificial hole which penetrates the second top electrode 70, and the sacrificial hole 80 is in communication with the air gap 60.
  • a sacrificial hole which may be a gap hole between the non-lead ends of the first top electrode and the second top electrode, and the sacrificial hole 81 communicates with the air gap 60.
  • 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 method of making an air gap inside the electrode is to deposit a sacrificial film and then remove it, which mainly involves how to arrange the sacrificial holes.
  • the sacrificial hole is located outside the effective area in the lateral direction of the resonator, which does not affect the performance of the resonator, but if it is too far from the acoustic effective area, the sacrificial film cannot be etched effectively; for example, the sacrificial hole 80 is located in the additional electrode (The electrode layer far from the piezoelectric layer in the gap electrode), because the sacrificial hole 80 is located outside the acoustically effective area composed of the top electrode, the piezoelectric layer, and the bottom electrode, it does not affect the acoustic resonance performance.
  • the arrangement of sacrificial holes may affect the electrical performance and reliability of the resonator; for example, the purpose of the arrangement of sacrificial holes 80 and 81 is to ensure that the number and total area of the holes are minimized under the premise of effective sacrifice, which is unreasonable The arrangement of, will cause the conductivity of the additional electrode (for example, corresponding to the second top electrode) 70 to decrease, fail to effectively increase the Q value at the series resonance, or cause the reliability of the additional electrode 70 to decrease.
  • the air gap structure in the electrode can be made by the process of arranging the sacrificial layer material and combining the etching agent release process.
  • the material of the sacrificial layer can be phosphorous-doped silicon dioxide (PSG)
  • the etchant can be liquid or gaseous hydrofluoric acid
  • the optional etchant can also be mixed with a certain proportion of buffer substances to control the reaction rate.
  • the top electrode (and/or bottom electrode) of the bulk acoustic wave resonator shown in FIG. 1A has a composite structure, wherein
  • the etching reaction first starts at the openings of the through holes 80 and/or 81. As the reaction proceeds, the etchant gradually enters the air gap 60 through the through holes 81 and/or 80, and removes the sacrificial layer in the air gap. material.
  • the top electrode is a gap electrode; and the first top electrode 50 and the second top electrode 70 are electrically connected at the electrode pin ends, and the first top electrode 50 and The second top electrode 70 defines at least one release channel 81 between the non-lead ends of the electrode (see FIGS. 1A and 1B).
  • FIG. 1B is a cross-sectional view of the generated bulk wave resonator taken along the line A1-A2 in FIG. 1A.
  • the etching process structure (1) is adopted, where the arrow direction indicates that the etchant enters the air gap 60 from the outside through the channel 80, and removes the sacrificial material in the air gap 60.
  • the channel 81 in FIG. 1B may represent several partial openings.
  • FIG. 1C is a top view of FIG. 1A taken along the line A1-A1 to generate a cross-sectional view, using the etching process structure (2), where the arrow direction indicates that the etchant enters the air gap 60 from the outside through the channel 80.
  • the top electrode is a gap electrode
  • the second electrode 70 is provided with at least one through hole 80, and the through hole constitutes a release channel.
  • the air gap is located in the bottom electrode, and the through hole 41 penetrates the piezoelectric layer 40 and the second bottom electrode 31 into the air gap 60.
  • the through hole 41 is located outside the range of the acoustic mirror 20 in the lateral direction.
  • the etchant gradually enters the air gap 60 through the through hole 41 along the arrow direction in FIG. 2A, and removes the sacrificial material in 60.
  • the bottom electrode is a gap electrode; and the release channel is located outside the effective area in the lateral direction of the resonator and penetrates the second bottom electrode 31.
  • the release channel 80 penetrates the piezoelectric layer 40 and the second bottom electrode 31, as shown in FIG. 2B.
  • a process structure in which only the through holes are reserved on the second bottom electrode 31 may also be adopted. Since the piezoelectric layer 40 has a loose microstructure and the main component of the etchant is hydrofluoric acid as small molecules/ions, during processing, the etchant can penetrate the piezoelectric layer 40 and then pass through the through holes on the second bottom electrode 31 Enter the air gap 60 and remove the sacrificial material in the air gap 60. In addition, the reaction product can also be released into the solution or gas environment outside the resonator through the piezoelectric layer 40 through the through hole.
  • FIGS. 3A and 3B a cross-sectional view of the bulk wave resonator process structure in which the bottom electrode of FIG. 3B has an air gap.
  • the air gap is located in the bottom electrode, and the through hole 41 penetrates the piezoelectric layer 40 and enters the release channel 21 of the cavity acoustic mirror.
  • the through hole 41 is located outside the range of the bottom electrode in the lateral direction.
  • the first bottom electrode 30 and the second bottom electrode 31 form a channel 83 on the side, which communicates with the air gap 60 and the release channel 21 of the cavity 20.
  • the etchant gradually enters the air gap 20 and the cavity 60 through the paths 41-21 and 41-83 along the arrow direction in FIG. 3A, and removes the sacrificial material in the two.
  • the air gap is located in the bottom electrode.
  • the first bottom electrode 30 has a plurality of through holes 84 which communicate with the air gap 60 and the cavity 20.
  • the etchant first enters the cavity 20 via the path 41-21 along the arrow in FIG. 4, and gradually removes the sacrificial material in 20.
  • the through hole 84 begins to be exposed, and the etchant will continue to pass through 84 enters the air gap 60 and gradually removes the sacrificial material in 60.
  • the bottom electrode is a gap electrode; the acoustic mirror 20 includes an acoustic mirror cavity; and the release channel includes a second outside the effective area in the lateral direction of the resonator.
  • a channel (corresponding to the through hole 41), the release channel further includes a second channel for communicating the first channel and the gap layer.
  • the first channel is a first through hole (corresponding to the through hole 41) that penetrates the piezoelectric layer; and the second channel includes a second through hole that penetrates the second electrode.
  • a through hole (corresponding to the through hole 84), the first through hole communicates with the acoustic mirror cavity, and the second through channel communicates with the acoustic mirror cavity.
  • the first channel is a first through hole penetrating the piezoelectric layer; on the side of the bottom electrode close to the first through hole, the end of the first electrode is located at the second through hole.
  • the second passage (corresponding to reference numeral 83) is formed above and between the two ends of the electrode.
  • the embodiment of the present invention also discloses a method of manufacturing a bulk acoustic wave resonator, which includes the following steps:
  • the sacrificial layer material is etched with an etchant to generate the gap layer.
  • 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 overlapping area of the top electrode, the bottom electrode, the acoustic mirror, and the piezoelectric layer in the thickness direction of the resonator defines the effective area of the resonator
  • the bottom electrode and/or the top electrode are gap electrodes.
  • the gap electrode has a first electrode and a second electrode.
  • the first electrode is attached to the piezoelectric layer.
  • a gap layer is defined between the first electrode and the second electrode.
  • the layer is located between the first electrode and the second electrode in the height direction of the resonator;
  • the gap electrode is provided with at least one release channel for forming the gap layer, the release channel is in communication with the gap layer, the release channel includes an electrode channel portion, the electrode channel portion is provided in an ineffective area of the electrode in.
  • the top electrode is a gap electrode
  • the first electrode and the second electrode are electrically connected at the electrode pin ends, and the first electrode and the second electrode define at least one electrode channel part between the electrode non-pin ends.
  • the top electrode is a gap electrode
  • the second electrode is provided with at least one through hole, and the through hole constitutes the electrode channel portion.
  • the bottom electrode is a gap electrode
  • the electrode channel part is located outside the effective area in the lateral direction of the resonator and penetrates the first electrode.
  • the release channel further includes a piezoelectric layer channel penetrating the piezoelectric layer, and the piezoelectric layer channel communicates with the electrode channel.
  • the bottom electrode is a gap electrode
  • the acoustic mirror includes an acoustic mirror cavity
  • the release channel includes a first channel located outside the effective area in the lateral direction of the resonator, and the release channel further includes a second channel for communicating the first channel with the gap layer.
  • the first channel is a first through hole penetrating the piezoelectric layer
  • the second channel includes at least one second through hole provided through the second electrode, the first through hole communicates with the acoustic mirror cavity, and the second through hole communicates with the acoustic mirror cavity,
  • the electrode channel part includes the second through hole.
  • the first channel is a first through hole penetrating the piezoelectric layer
  • the end of the first electrode is located above the end of the second electrode and the second channel is formed between the two ends.
  • the second channel communicates with the cavity of the acoustic mirror.
  • a filter comprising the bulk acoustic wave resonator described in any one of 1-9.
  • An electronic device comprising the bulk acoustic wave resonator according to any one of 1-9 or the filter according to 10.
  • the electrode channel portion is provided in the ineffective area of the electrode, and the ineffective area of the electrode here refers to the part of the electrode that does not participate in forming the effective area.
  • the electrode non-effective area includes the first electrode portion located in the non-effective area, and/or the second electrode, that is, the electrode portion that does not substantially participate in the main resonance of the effective area of the resonator.

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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；顶电极；底电极；压电层，设置在底电极与顶电极之间，其中：顶电极、底电极、声学镜和压电层在所述谐振器的厚度方向上的重叠区域限定谐振器的有效区域；底电极和/或顶电极为间隙电极，间隙电极具有第一电极与第二电极，第一电极贴附于所述压电层，第一电极与第二电极之间限定空隙层，空隙层在谐振器的高度方向上位于第一与第二电极之间；间隙电极设置有用于形成所述空隙层的释放通道，所述释放通道与所述空隙层连通，释放通道包括电极通道部，电极通道部设置于电极的非有效区域中。本发明还涉及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，以及一种制造上述谐振器的方法。

Description

体声波谐振器及其制造方法、滤波器和电子设备 技术领域
本发明的实施例涉及半导体领域，尤其涉及一种体声波谐振器及其制造方法，一种具有该谐振器的滤波器，以及一种具有该谐振器或者滤波器的电子设备。
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。
电子器件根据不同工作原理可以发挥不同的特性与优势，在所有电子器件中，利用压电效应(或逆压电效应)工作的器件是其中很重要一类，压电器件有着非常广泛的应用情景。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。
在体声波谐振器的微结构中集成空气间隙非常复杂，一方面需要考虑如何可靠地制造出空气间隙，另一方面要考虑形成空气间隙的方式/结构不影响谐振器性能。
发明内容
为缓解或解决上述问题，提出本发明。
根据本发明的实施例的一个方面，提出一种体声波谐振器，包括：
基底；
声学镜；
顶电极；
底电极；
压电层，设置在底电极与顶电极之间，
其中：
顶电极、底电极、声学镜和压电层在所述谐振器的厚度方向上的重叠区域限定所述谐振器的有效区域；
底电极和/或顶电极为间隙电极，所述间隙电极具有第一电极与第二电极，第一电极贴附于所述压电层，第一电极与第二电极之间限定空隙层，空隙层在谐振器的高度方向上位于第一电极与第二电极之间；
所述间隙电极设置有用于形成所述空隙层的至少一个释放通道，所述释放通道与所述空隙层连通，所述释放通道包括电极通道部，所述电极通道部设置于电极的非有效区域中。
本发明还提出了一种制造上述体声波谐振器的方法，包括以下步骤：
在所述第一电极与第二电极之间形成牺牲层材料，所述牺牲层材料在谐振器的厚度方向上位于第一电极与第二电极之间；
提供所述释放通道；
经由所述释放通道，利用刻蚀剂刻蚀牺牲层材料从而产生所述间隙层。
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1A为根据本发明的一个示例性实施例的顶电极具有空气间隙的体声波谐振器的工艺结构俯视图；
图1B为根据本发明的一个示例性实施例的沿图1A中的直线A1-A2剖开生成的、顶电极具有空气间隙的体波谐振器工艺结构剖视图，在图1B中，没有示出设置于顶电极的牺牲孔；
图1C为根据本发明的一个示例性实施例的沿图1A中的直线A1-A2剖开生成的、顶电极具有空气间隙的体波谐振器剖视图，采用刻蚀工艺结构，其中箭头方向表示刻蚀剂经通道从外部进入空气间隙，图1C中，没有示出顶电极的非引脚端的牺牲孔；
图2A为根据本发明的一个示例性实施例的底电极具有空气间隙的体声波谐振器工艺结构剖视图；
图2B为根据本发明的一个示例性实施例的底电极具有空气间隙的体声波谐振器工艺结构剖视图；
图3A为根据本发明的一个示例性实施例的底电极具有空气间隙的体声波谐振器俯视图；
图3B为根据本发明的一个示例性实施例的底电极具有空气间隙的体声波谐振器工艺结构剖视图；和
图4为根据本发明的一个示例性实施例的底电极具有空气间隙的体声波谐振器工艺结构剖视图。
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。
在本发明的附图中，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，在图1B中为空腔20，也可采用布拉格反射层及其他等 效形式，但是在底电极设置有刻蚀通道的情况下，声学镜为空腔结构。
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(LiNbO 3)、石英(Quartz)、铌酸钾(KNbO 3)或钽酸锂(LiTaO 3)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。
60：位于顶电极之中的空气间隙，处于第一顶电极50和第二顶电极70之间。
70：第二顶电极，材料选择范围同第一顶电极50，但具体材料不一定与第一顶电极50相同。
80：牺牲孔，贯穿第二顶电极70，牺牲孔80与空气间隙60连通。
81：牺牲孔，可以为第一顶电极与第二顶电极的非引脚端之间的间隙孔，牺牲孔81与空气间隙60连通。
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。
但是，在微结构中集成空气间隙并不简单，一方面需要考虑如何可靠地制造出空气间隙，另一方面要考虑形成空气间隙的方式/结构不影响谐振器性能。
就本专利发明来说，在电极内部制造空气间隙的方法为沉积牺牲薄膜后再将其清除掉，主要涉及到如何安排牺牲孔。
首先，牺牲孔在谐振器的横向方向上位于有效区域之外，这样不影 响谐振器性能，但如果距离声学有效区域太远又无法有效刻蚀牺牲薄膜；举例来说，牺牲孔80位于附加电极(间隙电极中远离压电层的电极层)中，因为牺牲孔80位于顶电极、压电层和底电极等组成的声学有效区域之外，不影响声学谐振性能。
其次，牺牲孔的安排可能影响谐振器的电学性能和可靠性；举例来说，牺牲孔80和81的安排目的是保证在有效牺牲的前提下，尽量减小孔的数量和总面积，不合理的安排将导致附加电极(例如对应于第二顶电极)70导电率下降，无法有效提高串联谐振处的Q值，或导致附加电极70可靠性下降。
本发明中位于电极内的空气间隙结构均可通过设置牺牲层材料结合刻蚀剂释放的工艺制成。其中牺牲层材料可选用掺磷二氧化硅(PSG)，刻蚀剂可选用液态或气态的氢氟酸，可选的刻蚀剂中还可混入一定比例的缓冲物质，控制反应速率。
具体地，图1A所示的体声波谐振器顶电极(和/或底电极)具有复合结构，其中
(1)在第一顶电极50和第二顶电极70之间具有若干通孔81。
(2)在第二顶电极70上具有若干通孔80。
值得注意的是，上述结构(1)和(2)是各自独立的实施方式，可同时应用于谐振器，也可分别单独应用于谐振器。
加工时，刻蚀反应首先从通孔80和/或81开口处开始，随着反应进行，刻蚀剂经通孔81和/或80逐步进入空气间隙60，并清除掉空气间隙内的牺牲层材料。
可选地，在本发明的谐振器中：所述顶电极为间隙电极；且所述第一顶电极50与第二顶电极70在电极引脚端电连接，所述第一顶电极50与第二顶电极70在电极非引脚端之间限定至少一个所述释放通道81(参见图1A与1B)。
具体参见图1B，其为沿图1A中的直线A1-A2剖开生成的体波谐振器的剖视图。在图1B中，采用刻蚀工艺结构(1)，其中箭头方向表示刻蚀剂经通道80从外部进入空气间隙60，并清除空气间隙60中的牺牲材料。 此处值得注意的是，图1B中通道81可以代表若干个局部开口。
另外可选地，图1C是俯视图图1A沿直线A1-A1剖开生成剖视图，采用刻蚀工艺结构(2)，其中箭头方向表示刻蚀剂经通道80从外部进入空气间隙60。即在本发明的谐振器中：所述顶电极为间隙电极；且所述第二电极70设置有至少一个贯穿通孔80，所述贯穿通孔构成释放通道。
还可选地，在图2A所示的谐振器工艺结构中，空气间隙位于底电极中，通孔41穿过压电层40和第二底电极31进入空气间隙60。其中通孔41在横向上位于声学镜20的范围之外。进行加工时，刻蚀剂沿图2A中箭头方向经通孔41逐渐进入空气间隙60，并清除60内的牺牲材料。在本发明的该实施例的谐振器中：所述底电极为间隙电极；且所述释放通道在谐振器的横向方向上位于有效区域之外且贯穿第二底电极31。
可选地，释放通道80贯穿所述压电层40与第二底电极31，如图2B所示。
可选地，也可如图3B所示，采用仅在第二底电极31上保留通孔的工艺结构。由于压电层40具有疏松微观结构，且刻蚀剂主要成分氢氟酸为小分子/离子，在加工时，刻蚀剂可透过压电层40然后经第二底电极31上的通孔进入空气间隙60，并清除空气间隙60内的牺牲材料。此外反应生成物同样也可经通孔透过压电层40被释放到谐振器之外的溶液或气体环境中。
在图3A和3B所示的谐振器工艺结构中，其中图3B底电极具有空气间隙的体波谐振器工艺结构剖视图。
具体地，空气间隙位于底电极中，通孔41穿过压电层40并进入空腔声学镜的释放通道21。其中通孔41在横向上位于底电极范围之外。此外，第一底电极30和第二底电极31在侧部形成通道83，该通道连通空气间隙60和空腔20的释放通道21。进行加工时，刻蚀剂沿图3A中箭头方向经路径41-21和41-83分别逐渐进入空气间隙20以及空腔60，并清除两者内的牺牲材料。
在图4所示的谐振器工艺结构中，空气间隙位于底电极中。第一底电极30具有若干通孔84，所述通孔84连通空气间隙60和空腔20。进行加工时，刻蚀剂沿图4中的箭头经路径41-21首先进入空腔20，并逐渐清 除20中的牺牲材料，随着反应进行，通孔84开始暴露，刻蚀剂会继续经84进入空气间隙60，并逐渐清除60内的牺牲材料。
因此，基于以上可知，在本发明的一个实施例中，底电极为间隙电极；声学镜20包括声学镜空腔；且所述释放通道包括在谐振器的横向方向上位于有效区域之外的第一通道(对应于通孔41)，所述释放通道还包括用于连通第一通道与所述空隙层的第二通道。
具体地，在本发明的谐振器中：所述第一通道为贯穿压电层的第一贯穿通孔(对应于通孔41)；且所述第二通道包括贯穿第二电极设置的第二贯穿通孔(对应于通孔84)，所述第一贯穿通孔与声学镜空腔相通，所述第二贯穿通道与所述声学镜空腔相通。
另外，在本发明的谐振器中：所述第一通道为贯穿压电层的第一贯穿通孔；在底电极的靠近第一贯穿通孔的一侧，第一电极的端部位于第二电极的端部的上方且在两个端部之间形成所述第二通道(对应于附图标记83)。
基于以上的刻蚀步骤的说明，本发明的实施例也公开了一种制造体声波谐振器的方法，包括以下步骤：
在间隙电极的第一电极与第二电极之间形成牺牲层材料，所述牺牲层材料在谐振器的厚度方向上位于第一电极与第二电极之间；
提供释放通道；
经由所述释放通道，利用刻蚀剂刻蚀牺牲层材料从而产生所述间隙层。
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，本发明还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；
顶电极；
底电极；
压电层，设置在底电极与顶电极之间，
其中：
顶电极、底电极、声学镜和压电层在所述谐振器的厚度方向上的重叠区域限定所述谐振器的有效区域；
底电极和/或顶电极为间隙电极，所述间隙电极具有第一电极与第二电极，第一电极贴附于所述压电层，第一电极与第二电极之间限定空隙层，空隙层在谐振器的高度方向上位于第一电极与第二电极之间；
所述间隙电极设置有用于形成所述空隙层的至少一个释放通道，所述释放通道与所述空隙层连通，所述释放通道包括电极通道部，所述电极通道部设置于电极的非有效区域中。
2、根据1所述的谐振器，其中：
所述顶电极为间隙电极；且
所述第一电极与第二电极在电极引脚端电连接，所述第一电极与第二电极在电极非引脚端之间限定至少一个所述电极通道部。
3、根据1所述的谐振器，其中：
所述顶电极为间隙电极；且
所述第二电极设置有至少一个贯穿通孔，所述贯穿通孔构成所述电极通道部。
4、根据1所述的谐振器，其中：
所述底电极为间隙电极；且
所述电极通道部在谐振器的横向方向上位于有效区域之外且贯穿所述第一电极。
5、根据4所述的谐振器，其中：
所述释放通道还包括贯穿所述压电层的压电层通道，所述压电层通道与所述电极通道相通。
6、根据1所述的谐振器，其中：
所述底电极为间隙电极；
所述声学镜包括声学镜空腔；且
所述释放通道包括在谐振器的横向方向上位于有效区域之外的第一通道，所述释放通道还包括用于连通第一通道与所述空隙层的第二通道。
7、根据6所述的谐振器，其中：
所述第一通道为贯穿压电层的第一贯穿通孔；且
所述第二通道包括贯穿第二电极设置的至少一个第二贯穿通孔，所述第一贯穿通孔与声学镜空腔相通，所述第二贯穿通孔与所述声学镜空腔相通，所述电极通道部包括所述第二贯穿通孔。
8、根据6所述的谐振器，其中：
所述第一通道为贯穿压电层的第一贯穿通孔；且
在底电极的靠近第一贯穿通孔的一侧，第一电极的端部位于第二电极的端部的上方且在两个端部之间形成所述第二通道。
9、根据8所述的谐振器，其中：
所述第二通道与所述声学镜空腔相通。
10、一种包括1-9中任一项所述的体声波谐振器的滤波器。
11、一种包括1-9中任一项所述的体声波谐振器或10所述的滤波器的电子设备。
需要指出的是，在本发明中，电极通道部设置于电极的非有效区域中，这里的电极的非有效区域表示电极中不参与形成有效区域的部分。例如，对于图1C中，附加电极(第二顶电极)中设置通孔80的部位虽然在谐振器的厚度方向上的投影中位于有效区域的范围内但是其并非是用于形成有效区域的组成部分。因此，电极非有效区域包括位于非有效区域的第一电极部分，和/或第二电极，即基本上不参与谐振器有效区域主谐振的电极部分。
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 (12)

  1. 一种体声波谐振器，包括：
    基底；
    声学镜；
    顶电极；
    底电极；
    压电层，设置在底电极与顶电极之间，
    其中：
    顶电极、底电极、声学镜和压电层在所述谐振器的厚度方向上的重叠区域限定所述谐振器的有效区域；
    底电极和/或顶电极为间隙电极，所述间隙电极具有第一电极与第二电极，第一电极贴附于所述压电层，第一电极与第二电极之间限定空隙层，空隙层在谐振器的高度方向上位于第一电极与第二电极之间；
    所述间隙电极设置有用于形成所述空隙层的至少一个释放通道，所述释放通道与所述空隙层连通，所述释放通道包括电极通道部，所述电极通道部设置于电极的非有效区域中。
  2. 根据权利要求1所述的谐振器，其中：
    所述顶电极为间隙电极；且
    所述第一电极与第二电极在电极引脚端电连接，所述第一电极与第二电极在电极非引脚端之间限定至少一个所述电极通道部。
  3. 根据权利要求1或2所述的谐振器，其中：
    所述顶电极为间隙电极；且
    所述第二电极设置有至少一个贯穿通孔，所述贯穿通孔构成所述电极通道部。
  4. 根据权利要求1所述的谐振器，其中：
    所述底电极为间隙电极；且
    所述电极通道部在谐振器的横向方向上位于有效区域之外且贯穿所述第一电极。
  5. 根据权利要求4所述的谐振器，其中：
    所述释放通道还包括贯穿所述压电层的压电层通道，所述压电层通道 与所述电极通道相通。
  6. 根据权利要求1所述的谐振器，其中：
    所述底电极为间隙电极；
    所述声学镜包括声学镜空腔；且
    所述释放通道包括在谐振器的横向方向上位于有效区域之外的第一通道，所述释放通道还包括用于连通第一通道与所述空隙层的第二通道。
  7. 根据权利要求6所述的谐振器，其中：
    所述第一通道为贯穿压电层的第一贯穿通孔；且
    所述第二通道包括贯穿第二电极设置的至少一个第二贯穿通孔，所述第一贯穿通孔与声学镜空腔相通，所述第二贯穿通孔与所述声学镜空腔相通，所述电极通道部包括所述第二贯穿通孔。
  8. 根据权利要求6所述的谐振器，其中：
    所述第一通道为贯穿压电层的第一贯穿通孔；且
    在底电极的靠近第一贯穿通孔的一侧，第一电极的端部位于第二电极的端部的上方而间隔开且在两个端部之间形成孔道，所述第二通道包括所述孔道，所述电极通道部包括所述孔道。
  9. 根据权利要求8所述的谐振器，其中：
    所述第二通道与所述声学镜空腔相通。
  10. 一种包括权利要求1-9中任一项所述的体声波谐振器的滤波器。
  11. 一种包括根据权利要求1-9中任一项所述的体声波谐振器或权利要求10所述的滤波器的电子设备。
  12. 一种制造根据权利要求1-9任一项所述的体声波谐振器的方法，包括以下步骤：
    在所述第一电极与第二电极之间形成牺牲层材料，所述牺牲层材料在谐振器的厚度方向上位于第一电极与第二电极之间；
    提供所述释放通道；
    经由所述释放通道，利用刻蚀剂刻蚀牺牲层材料从而产生所述间隙层。
PCT/CN2020/088663 2019-10-26 2020-05-06 体声波谐振器及其制造方法、滤波器和电子设备 WO2021077713A1 (zh)

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