WO2024007404A1 - 一种薄膜体声波谐振器 - Google Patents

一种薄膜体声波谐振器 Download PDF

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Publication number
WO2024007404A1
WO2024007404A1 PCT/CN2022/110237 CN2022110237W WO2024007404A1 WO 2024007404 A1 WO2024007404 A1 WO 2024007404A1 CN 2022110237 W CN2022110237 W CN 2022110237W WO 2024007404 A1 WO2024007404 A1 WO 2024007404A1
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WIPO (PCT)
Prior art keywords
protrusion
protruding frame
thin film
extending
frame
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PCT/CN2022/110237
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English (en)
French (fr)
Inventor
杨帅
吴珂
王超
张丽蓉
庄智强
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瑞声声学科技(深圳)有限公司
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Publication of WO2024007404A1 publication Critical patent/WO2024007404A1/zh

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Classifications

    • 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
    • H03H9/02047—Treatment of substrates
    • 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
    • H03H9/02062—Details relating to the vibration mode
    • 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
    • H03H9/05—Holders; Supports
    • H03H9/0504—Holders; Supports for bulk acoustic wave devices
    • H03H9/0514—Holders; Supports for bulk acoustic wave devices consisting of mounting pads or bumps
    • 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 present invention belongs to the field of resonators, and more specifically, relates to a thin film bulk acoustic resonator.
  • the film bulk acoustic resonator is a resonator manufactured using a silicon substrate, MEMS technology and thin film technology.
  • functions such as image elimination, spurious filtering, and channel selection can be realized, and it has the characteristics of high Q value and easy miniaturization.
  • Conventional thin film bulk acoustic resonators usually consist of a bottom electrode, a piezoelectric layer and a top electrode.
  • the piezoelectric film moves in the longitudinal direction.
  • Mechanical vibration is generated on the motor and body acoustic waves are formed. Since the surfaces of the upper and lower motors have total reflection boundary conditions, the propagating body acoustic waves will be constrained in the transducer.
  • the body acoustic waves of a specific frequency form standing waves that propagate longitudinally. Under the action of the piezoelectric effect, these bulk acoustic waves are converted into electrical signals.
  • the bulk acoustic wave at the resonant frequency has the largest electrical signal intensity, and the bulk acoustic wave at the anti-resonance frequency has the smallest electrical signal intensity, thus realizing the control of different frequencies. Selection of electrical signals.
  • the acoustic wave mode excited by a conventional thin film bulk acoustic resonator not only includes the expected longitudinal waves propagating along the thickness direction of the film, but also includes propagation along the horizontal direction of the film.
  • Transverse parasitic acoustic waves (mainly Rayleigh-Lamb waves). When these transverse parasitic acoustic waves escape from the edge of the resonance zone to the outside of the resonance zone, they will take away the energy in the resonance zone, resulting in the quality factor (Q) of the resonator. value) decreases.
  • the purpose of the present invention is to provide a thin film bulk acoustic resonator, aiming to solve the problem of low quality factor of the related resonator.
  • the present invention provides a thin film bulk acoustic resonator, which includes a substrate, an acoustic reflection structure provided on one side of the substrate, and a bottom electrode stacked on one side of the acoustic reflection structure. , a piezoelectric film covering the bottom electrode and a top electrode stacked on the side of the piezoelectric film away from the bottom electrode. The side of the top electrode away from the piezoelectric film is provided with interdigitated protrusions.
  • the interdigitated raised frame includes a first raised frame and a second raised frame that are relatively spaced apart, and extend toward each other from the first raised frame and the second raised frame respectively. At least one pair of interdigital structures are formed by overlapping, and each of the interdigital structures includes two interdigitates spaced apart by a preset distance along the overlapping direction.
  • the interdigitated structure includes a first extending protrusion and a second extending protrusion connected to the side of the first protruding frame close to the second protruding frame and spaced apart from each other, and are connected to the second protruding frame.
  • the protruding frame is close to the third extending protrusion and the fourth extending protrusion arranged at intervals on one side of the first protruding frame, wherein the distance between the first extending protrusion and the third extending protrusion is preset. distance and overlap to form an interdigital structure; the second extension protrusion and the fourth extension protrusion are spaced apart.
  • the second extension protrusion is spaced directly opposite the fourth extension protrusion in its extension direction, or the second extension protrusion and the fourth extension protrusion are spaced apart from each other by a preset distance. Overlap to form an interdigitated structure.
  • the interdigital structure when the second extension protrusion is spaced apart from the fourth extension protrusion in its extension direction, the interdigital structure further includes a link connecting the second extension protrusion and the fourth extension protrusion.
  • the connecting bump of the extension bump is not limited to, but not limited to,
  • the end of the second extension protrusion close to the second protrusion frame is bent and extended toward the direction of the first extension protrusion with a first additional protrusion
  • the third extension protrusion is close to the first extension protrusion.
  • the end of the first protruding frame is bent and extended toward the direction of the fourth extending protrusion with a second additional protrusion; the first additional protrusion is arranged parallel to the second protruding frame at a predetermined interval. The distance overlaps to form an interdigital structure, and the second additional protrusion is arranged parallel to the first protrusion frame and overlaps at a preset distance to form an interdigital structure.
  • the first extension protrusion and the second extension protrusion are respectively connected to opposite ends of the first protrusion frame along its extension direction
  • the third extension protrusion and the fourth extension protrusion are connected to opposite ends of the first protrusion frame along its extension direction.
  • the extension protrusions are respectively connected to positions near the ends of the second protrusion frame along its extension direction and are located around the first protrusion frame, the first extension protrusion and the second extension protrusion. into the space.
  • the preset distance is an integer multiple of a quarter wavelength of the transverse parasitic acoustic wave.
  • the acoustic reflection structure is a cavity formed inside the substrate or a cavity formed on a side of the substrate close to the bottom electrode or a Bragg reflection formed on the surface of the substrate.
  • the acoustic reflection structure is a cavity, the projection of the bottom electrode along the thickness direction of the thin film bulk acoustic resonator is at least partially located outside the acoustic reflection structure.
  • the spatial area formed by overlapping the acoustic reflection structure, the bottom electrode, the piezoelectric film and the top electrode along the thickness direction of the thin film bulk acoustic resonator is a resonance area, and the interdigital protruding frame is located It is arranged in the resonance area and close to the edge of the resonance area.
  • the interdigitated protruding frame is made of metal material or dielectric material or a composite material of metal material and dielectric material.
  • the present invention can reflect the transverse Rayleigh-Lamb wave according to the difference in acoustic impedance in different areas, thereby improving the resistance Rp and Qp corresponding to the anti-resonant frequency fp of the resonator.
  • the interdigitated raised frame technology of the present invention can target two or more transverse Rayleigh-Lamb wave acoustic waves.
  • the acoustic wave is reflected to achieve high reflection efficiency, further reducing the energy leaked to the outside of the resonant area, and increasing the anti-resonant frequency fp of the resonator corresponding to the resistors Rp and Qp.
  • the interdigitated raised frame has a non-closed-loop structure, which is conducive to the realization of the peeling process. After using the peeling process, peeling residue is not easy to occur, thus ensuring the yield of the resonator and not increasing the number of preparation process steps of the resonator. .
  • Figure 1 is a top view of a thin film bulk acoustic resonator provided by a first implementation mode of the present invention
  • Figure 2a is an A-A cross-sectional view of the first thin film bulk acoustic resonator provided by the first implementation mode of the present invention
  • Figure 2b is an A-A cross-sectional view of the second thin film bulk acoustic resonator provided by the first implementation mode of the present invention
  • Figure 2c is an A-A cross-sectional view of the third thin film bulk acoustic resonator provided by the first implementation mode of the present invention.
  • Figure 3 is a comparison diagram of the impedance curves of the thin film bulk acoustic resonator provided by the first implementation of the present invention and the prior art thin film bulk acoustic resonator;
  • Figure 4 is a top view of the thin film bulk acoustic resonator provided by the second implementation mode of the present invention.
  • Figure 5 is a top view of the thin film bulk acoustic resonator provided by the third implementation of the present invention.
  • Figure 6 is a top view of a thin film bulk acoustic resonator provided by the fourth implementation mode of the present invention.
  • FIG. 7 is a top view of a thin film bulk acoustic resonator provided in a fifth implementation manner of the present invention.
  • the thin film bulk acoustic resonator is rectangular as an example, but the actual thin film bulk acoustic resonator is not limited to a rectangular shape. In practice, it can also be other polygonal or elliptical shapes.
  • the present invention provides a thin film bulk acoustic resonator.
  • the resonator includes a substrate 1, an acoustic reflection structure 2 arranged on one side of the substrate 1, and an acoustic reflection structure 2 stacked on one side of the substrate 1.
  • the bottom electrode 3, the piezoelectric film 4 covering the bottom electrode 3, and the top electrode 5 stacked on the side of the piezoelectric film 4 away from the bottom electrode 3, the side of the top electrode 5 away from the piezoelectric film 4 is provided with an interdigitated
  • the raised frame, the interdigitated raised frame includes a first raised frame 61 and a second raised frame 62 that are relatively spaced apart, and extend from the first raised frame 61 and the second raised frame 62 toward each other and are spaced apart from each other. At least one pair of interdigital structures formed by overlapping and predetermined distance.
  • the thin film bulk acoustic resonator provided by the present invention can reflect transverse Rayleigh-Lamb waves according to the difference in acoustic impedance Za in different areas to improve the Q value of the resonator, which is comparable to the annular convex frame technology in the prior art.
  • the interdigitated structure formed by the interdigitated protruding frame 6 can reflect two or more transverse Rayleigh-Lamb wave acoustic waves to achieve higher reflection efficiency and further reduce leakage to the outside of the resonance zone. Energy, increase the anti-resonant frequency fp of the resonator and the corresponding resistors Rp and Qp.
  • FIG 3 is a comparison diagram of the impedance curves of the interdigitated raised frame FBAR (thin film bulk acoustic resonator) provided by the present invention and the conventional FBAR and FBAR with raised frames in the prior art.
  • the interdigitated raised frame FBAR has The widths W1 and W2 are respectively designed to be integer multiples of 1/4 wavelength of two of the four Rayleigh-Lamb wave acoustic wave modes (S0, A0, S1 and A1).
  • the Rp of the interdigitated raised frame FBAR provided by the present invention is significantly higher than the Rp of the FBAR with raised frames in the prior art, which shows that the interdigitated raised frame has an impact on the transverse Rayleigh-Blue
  • the higher reflection efficiency of M-wave acoustic waves also indicates that the FBAR using the interdigitated raised frame has a higher Qp.
  • the interdigitated protruding frame 6 in the present invention has a non-closed loop structure, which is beneficial to improving the problem of peeling residue caused by the closed loop of the existing protruding frame without increasing the number of manufacturing process steps for the resonator.
  • the interdigital structure includes a first extending protrusion 611 and a second extending protrusion 612 that are spaced apart from each other on the side of the first protruding frame 61 close to the second protruding frame 62 and are connected to the second protruding frame 62
  • the third extension protrusion 621 and the fourth extension protrusion 622 are located close to one side of the first protrusion frame 61 and are spaced apart from each other.
  • the first extension protrusion 611 and the third extension protrusion 621 are separated by a preset distance and intersect with each other.
  • the stacks form an interdigitated structure; the second extension protrusion 612 and the fourth extension protrusion 622 are spaced apart.
  • the second extension protrusion 612 is spaced apart from the fourth extension protrusion 622 in its extension direction, or the second extension protrusion 612 and the fourth extension protrusion 622 are separated by a preset distance and overlap to form an interdigitated structure. .
  • the first extending protrusion 611 is connected to the end of the first protruding frame 61
  • the second extending protrusion 612 is connected to the first protruding frame 61 and is connected to the first protruding frame 61
  • the other end of a protruding frame 61 has a spacing
  • the third extending protrusion 621 is connected to the second protruding frame 62 and has a spacing from one end of the second protruding frame 62
  • the fourth extending protrusion 622 is connected to the second protrusion.
  • the other end of the frame 62 is connected to the end of the first protruding frame 61 .
  • the interdigitated protruding frame 6 has a centrally symmetrical layout as a whole.
  • the first extending protrusions 611 and the third extending protrusions 621 overlap at a preset distance to form an interdigitated structure.
  • the second extending protrusions 612 and the fourth extending protrusion 622 overlap at a preset distance to form an interdigitated structure.
  • first extension protrusion 611 and the second extension protrusion 612 are respectively connected to the first protrusion frame 61 and extend along it.
  • the third extending protrusion 621 and the fourth extending protrusion 622 are respectively connected to positions near the ends of the second protruding frame 62 along its extending direction and are located between the first protruding frame 61 and the fourth extending protrusion 622 .
  • the first extending protrusion 611 is connected to the end of the first protruding frame 61
  • the second extending protrusion 612 is connected to the other end of the first protruding frame 61
  • the third extending protrusion 621 is connected to the third protruding frame 61 .
  • the two protruding frames 62 are spaced apart from one end of the second protruding frame 62
  • the fourth extending protrusion 622 is connected to the second protruding frame 62 and is spaced apart from the other end of the second protruding frame 62 .
  • the first extension protrusion 611 and the third extension protrusion 621 overlap at a preset distance to form an interdigital structure
  • the second extension protrusion 612 and the fourth extension protrusion 612 overlap with each other at a preset distance.
  • 622 overlap at a preset distance to form an interdigitated structure.
  • the end of the second extension protrusion 612 close to the second protrusion frame 62 faces the direction of the first extension protrusion 611
  • a first additional protrusion 613 is bent and extended, and a second additional protrusion 623 is bent and extended at the end of the third extension protrusion 621 close to the first protrusion frame 61 toward the direction of the fourth extension protrusion 622;
  • the protrusions 613 are arranged parallel to the second protruding frame 62 and overlap at a preset distance to form an interdigital structure.
  • the second additional protrusions 623 are arranged parallel to the first protruding frame 61 and overlap at a preset distance to form an interdigital structure.
  • the first extension protrusion 611 is connected to the end of the first protrusion frame 61
  • the second extension protrusion 612 is connected to the end of the first protrusion frame 61
  • the third extending protrusion 621 is connected to the second protruding frame 62 and has a distance from one end of the second protruding frame 62
  • the fourth extending protrusion 622 is connected to the second protruding frame 62. Two raised ends of the frame 62 are at the other end.
  • the first extension protrusion 611 and the third extension protrusion 621 overlap at a preset distance to form an interdigital structure, and the second extension protrusion 612 is in contact with the fourth extension protrusion 622 in its extension direction. Facing the interval setting.
  • the interdigital structure further includes connecting the second extension protrusion 622 .
  • the connecting protrusion 63 of the protrusion 612 and the fourth extending protrusion 622 that is, this implementation is: based on the fourth implementation, the second extending protrusion 612 and the fourth extending protrusion 622 are connected as one body and along the same direction extension.
  • the preset distance is an integer multiple of a quarter wavelength of the transverse parasitic acoustic wave.
  • the acoustic reflection structure 2 may be a cavity formed inside the substrate 1 or a cavity formed on a side of the substrate 1 close to the bottom electrode 3 or a Bragg reflector formed on the surface of the substrate 1.
  • the acoustic reflection structure 2 is When the reflective structure is a cavity, the projection of the bottom electrode 3 along the thickness direction of the thin film bulk acoustic resonator is at least partially located outside the acoustic reflective structure 2 .
  • the acoustic reflection structure 2 in Figure 2a is a cavity formed inside the substrate 1; the acoustic reflection structure 2 in Figure 2b is a cavity formed above the substrate 1. In this case, it can be achieved by connecting the substrate 1 and the bottom electrode.
  • a support layer is provided between 3 to form a cavity; in Figure 2c, the acoustic reflection structure 2 is formed as a Bragg reflector on the surface of the substrate 1.
  • the Bragg reflector includes low acoustic impedances alternately arranged along the thickness direction of the thin film bulk acoustic resonator.
  • the spatial area formed by the acoustic reflection structure 2, the bottom electrode 3, the piezoelectric film 4 and the top electrode 5 are overlapping together along the thickness direction of the thin film bulk acoustic resonator is the resonance area, and the interdigital protruding frame 6 is located in the resonance area. It is located within the zone and close to the edge of the resonance zone.
  • the interdigitated protruding frame 6 is made of metal material or dielectric material or a composite material of metal material and dielectric material. Specifically, it can be one or more of Al, Pt, Au, W, Mo, Ru, Ir, AlN and Si3N4.
  • the width of the interdigitated raised frame can range from 1nm to 20000nm, such as 50nm, 500nm, 5000nm, 10000nm, 15000nm, etc.; the height can range from 1nm to 10000nm, such as 10nm, 100nm, 1000nm, 3000nm, 5000nm, 7000nm, 8000nm. Etc., the widths of the two raised frames that make up the interdigitated structure can be different or the same.
  • the width of the raised frame near the inside of the enclosed space is greater than the width of the raised frame near the outside, and the ratio of the width of the raised frame near the inside of the enclosed space to the width of the raised frame near the outside can be 1.1-2 between, such as 1.3, 1.5, 1.7, etc.
  • the width of the raised frame near the inside of the enclosed space can also be smaller than the width of the raised frame near the outside, and the width of the raised frame near the inside of the enclosed space and The width ratio of the raised frame near the outside can be between 0.5-0.95, such as 0.6, 0.7, 0.8, etc.

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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

一种薄膜体声波谐振器，包括衬底(1)、设置于衬底(1)一侧的声学反射结构(2)、叠设在声学反射结构(2)一侧的底电极(3)、覆盖底电极(3)的压电薄膜(4)以及叠设在压电薄膜(4)的远离底电极(3)侧的顶电极(5)，顶电极(5)远离压电薄膜(4)的一侧设置有叉指型凸起框架(6)，叉指型凸起框架(6)包括相对设置的第一凸起框架(61)和第二凸起框架(62)，自第一凸起框架(61)和第二凸起框架(62)分别相向延伸且间隔预设距离并交叠形成的至少一对叉指结构，每一叉指结构包括沿交叠方向间隔预设距离的两个叉指，能够对两种或两种以上横向瑞利-兰姆波进行反射以实现高的反射效率，改善谐振器的反谐振频率对应的Q值，能够改善现有凸起框架闭环带来的剥离残留问题。

Description

一种薄膜体声波谐振器 技术领域
本发明属于谐振器领域，更具体地，涉及一种薄膜体声波谐振器。
 背景技术
薄膜体声波谐振器（FBAR）是一种使用硅衬底、借助MEMS技术以及薄膜技术制造而成的谐振器。在无线收发器中能够实现镜像消除、寄生滤波和信道选择等功能，具有较高Q值和易实现微型化等特点。
常规的薄膜体声波谐振器通常由底电极、压电层和顶电极构成，工作时当射频电信号施加在顶电极和底电极上，在逆压电效应的作用下，压电薄膜在纵向方向上产生机械振动，并形成体声波，由于上、下电机表面具有全反射边界条件，传播的体声波将会被约束在换能器中，特定频率的体声波形成纵向传播的驻波。在压电效应的作用下，这些体声波被转换成电信号，其中谐振频率处的体声波转换的电信号强度最大，反谐振频率处的体声波转换的电信号强度最小，从而实现对不同频率电学信号的选择。但是由于边界电学条件和生长的压电层材料C轴存在倾斜等因素，常规的薄膜体声波谐振器激发的声学波模式不仅有期望的沿薄膜厚度方向传播的纵波，也包含沿薄膜水平方向传播的横向寄生声学波（主要是瑞利-兰姆波），这些横向寄生声学波从谐振区边缘逃逸到谐振区外部时，会将谐振区的能量带走，从而导致谐振器的品质因数（Q值）减少。
 技术问题
针对相关技术的缺陷，本发明的目的在于提供一种薄膜体声波谐振器，旨在解决相关的谐振器品质因数不高的问题。
 技术解决方案
为实现上述目的，本发明提供了一种薄膜体声波谐振器，该谐振器包括衬底、设置于所述衬底一侧的声学反射结构、叠设在所述声学反射结构一侧的底电极、覆盖所述底电极的压电薄膜以及叠设在所述压电薄膜的远离所述底电极侧的顶电极，所述顶电极的远离所述压电薄膜的一侧设置有叉指型凸起框架，所述叉指型凸起框架包括相对间隔设置的第一凸起框架和第二凸起框架，以及自所述第一凸起框架和所述第二凸起框架分别相向延伸且彼此交叠形成的至少一对叉指结构，每一所述叉指结构包括沿交叠方向间隔预设距离的两个叉指。
优选的，所述叉指结构包括连接于所述第一凸起框架靠近所述第二凸起框架一侧且间隔设置的第一延伸凸起和第二延伸凸起，连接于所述第二凸起框架靠近所述第一凸起框架一侧且间隔设置的第三延伸凸起和第四延伸凸起，其中所述第一延伸凸起与所述第三延伸凸起之间间隔预设距离并交叠形成叉指结构；所述第二延伸凸起与所述第四延伸凸起之间间隔设置。
优选的，所述第二延伸凸起在其延伸方向上与所述第四延伸凸起正对间隔设置或所述第二延伸凸起与所述第四延伸凸起之间间隔预设距离并交叠形成叉指结构。
优选的，当所述第二延伸凸起在其延伸方向上与所述第四延伸凸起正对间隔设置时，所述叉指结构还包括连接所述第二延伸凸起和所述第四延伸凸起的连接凸起。
优选的，所述第二延伸凸起靠近所述第二凸起框架的端部朝向所述第一延伸凸起的方向弯折延伸有第一附加凸起，所述第三延伸凸起靠近所述第一凸起框架的端部朝向所述第四延伸凸起的方向弯折延伸有第二附加凸起；所述第一附加凸起与所述第二凸起框架平行设置并间隔预设距离交叠形成叉指结构，所述第二附加凸起与所述第一凸起框架平行设置并间隔预设距离交叠形成叉指结构。
优选的，所述第一延伸凸起和所述第二延伸凸起分别连接于所述第一凸起框架沿其延伸方向的相对两端部，所述第三延伸凸起和所述第四延伸凸起分别连接于所述第二凸起框架沿其延伸方向的靠近端部的位置处并位于所述第一凸起框架、所述第一延伸凸起和所述第二延伸凸起围成的空间内。
优选的，所述预设距离为横向寄生声学波四分之一波长的整数倍。
优选的，所述声学反射结构为形成在所述衬底内部的空腔或为形成在所述衬底靠近所述底电极的一侧的空腔或为形成在所述衬底表面的布拉格反射镜，当所述声学反射结构为空腔时，所述底电极沿所述薄膜体声波谐振器的厚度方向上的投影至少部分位于所述声学反射结构外。
优选的，所述声学反射结构、底电极、压电薄膜和顶电极沿所述薄膜体声波谐振器的厚度方向共同交叠重合形成的空间区域为谐振区，所述叉指型凸起框架位于所述谐振区内且靠近所述谐振区的边缘设置。
优选的，所述叉指型凸起框架为金属材料或介电材料或金属材料和介电材料的复合材料。
 有益效果
总体而言，通过本发明所构思的以上技术方案与现有技术相比，具有以下有益效果：
本发明通过设置叉指型凸起框架，能够依据不同区域的声阻抗差异实现对横向瑞利-兰姆波的反射，进而改善谐振器的反谐振频率fp对应的电阻Rp和Qp。与现有环形凸起框架技术（主要针对一种横向瑞利-兰姆波声学波）相比，本发明的叉指型凸起框架技术可以对两种或两种以上横向瑞利-兰姆波声学波进行反射以实现高的反射效率，进一步减少泄漏到谐振区外部的能量，提高谐振器的反谐振频率fp对应的电阻Rp和Qp。此外，该叉指型凸起框架为非闭环结构，有利于剥离工艺的实现，使用剥离工艺后不容易发生剥离残留现象，进而保证谐振器的良率，还不会增加谐振器的制备工艺步骤。
 附图说明
图1是本发明第一种实现方式提供的薄膜体声波谐振器的俯视图；
图2a是本发明第一种实现方式提供的第一种薄膜体声波谐振器的A-A向剖视图；
图2b是本发明第一种实现方式提供的第二种薄膜体声波谐振器的A-A向剖视图；
图2c是本发明第一种实现方式提供的第三种薄膜体声波谐振器的A-A向剖视图；
图3是本发明第一种实现方式提供的薄膜体声波谐振器与现有技术的薄膜体声波谐振器的阻抗曲线比较图；
图4是本发明第二种实现方式提供的薄膜体声波谐振器的俯视图；
图5是本发明第三种实现方式提供的薄膜体声波谐振器的俯视图；
图6是本发明第四种实现方式提供的薄膜体声波谐振器的俯视图；
图7是本发明第五种实现方式提供的薄膜体声波谐振器的俯视图。
 本发明的实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。此处描述的具体实施例中薄膜体声波谐振器以矩形为例，但实际并不限制薄膜体声波谐振器为矩形，实际中也可以为其他的多边形或椭圆形。
本发明提供了一种薄膜体声波谐振器，结合图1、2a-2c，该谐振器包括衬底1、设置于衬底1一侧的声学反射结构2、叠设在声学反射结构2一侧的底电极3、覆盖底电极3的压电薄膜4以及叠设在压电薄膜4的远离底电极3侧的顶电极5，顶电极5的远离压电薄膜4的一侧设置有叉指型凸起框架，叉指型凸起框架包括相对间隔设置的第一凸起框架61和第二凸起框架62，以及自第一凸起框架61和第二凸起框架62分别相向延伸且彼此间隔预设距离并交叠形成的至少一对叉指结构。
本发明提供的薄膜体声波谐振器能够根据不同区域的声阻抗Za差异实现对横向瑞利-兰姆波的反射，以改善谐振器的Q值，与现有技术中的环形凸起框架技术相比，叉指型凸起框架6形成的叉指结构可以对两种或两种以上的横向瑞利-兰姆波声学波进行反射以实现较高的反射效率，进一步减少泄漏到谐振区外部的能量，提高谐振器的反谐振频率fp对应的电阻Rp和Qp。图3是本发明提供的叉指型凸起框架FBAR（薄膜体声波谐振器）与现有技术中普通FBAR、具有凸起框架FBAR的阻抗曲线比较图，其中该叉指型凸起框架FBAR的宽度W1和W2分别设计为4种瑞利-兰姆波声学波（S0、A0、S1和A1）模式中的2种模式的1/4波长的整数倍。从图3的结果可以看出本发明提供的叉指型凸起框架FBAR的Rp明显高于现有技术中具有凸起框架FBAR的Rp，这表明叉指型凸起框架对横向瑞利-兰姆波声学波的反射效率更高，也表明使用叉指型凸起框架的FBAR具有更高的Qp。同时，本发明中叉指型凸起框架6为非闭环结构，有利于改善现有凸起框架闭环带来的剥离残留的问题，不会增加谐振器的制备工艺步骤。
进一步地，叉指结构包括连接于第一凸起框架61靠近第二凸起框架62一侧相互间隔设置的第一延伸凸起611和第二延伸凸起612，连接于第二凸起框架62靠近第一凸起框架61一侧且相互间隔设置的第三延伸凸起621和第四延伸凸起622，其中第一延伸凸起611与第三延伸凸起621之间间隔预设距离并交叠形成叉指结构；第二延伸凸起612与第四延伸凸起622间隔设置。
进一步地，第二延伸凸起612在其延伸方向上与第四延伸凸起622正对间隔设置或第二延伸凸起612与第四延伸凸起622间隔预设距离并交叠形成叉指结构。
基于上述设计思路，本申请提供五种实现方式的设计示例：
在本申请的第一种实现方式中，结合图1，第一延伸凸起611连接于第一凸起框架61的端部，第二延伸凸起612连接于第一凸起框架61且和第一凸起框架61的另一端具有间距，第三延伸凸起621连接于第二凸起框架62且和第二凸起框架62的一端具有间距，第四延伸凸起622连接于第二凸起框架62的另一端的端部。因此，在本实现方式中，叉指型凸起框架6整体为中心对称布局，第一延伸凸起611和第三延伸凸起621间隔预设距离交叠形成叉指结构，第二延伸凸起612和第四延伸凸起622间隔预设距离交叠形成叉指结构。
在本申请的第二种实现方式中，结合图4，与第一种实现方式不同的是，第一延伸凸起611和第二延伸凸起612分别连接于第一凸起框架61沿其延伸方向的相对两端部，第三延伸凸起621和第四延伸凸起622分别连接于第二凸起框架62沿其延伸方向的靠近端部的位置处并位于第一凸起框架61、第一延伸凸起611和第二延伸凸起612围成的空间内。具体的，第一延伸凸起611连接于第一凸起框架61的端部，第二延伸凸起612连接于第一凸起框架61的另一端端部，第三延伸凸起621连接于第二凸起框架62且和第二凸起框架62的一端具有间距，第四延伸凸起622连接于第二凸起框架62且和第二凸起框架62的另一端具有间距。因此，以附图视角为例，在本实现方式中，第一延伸凸起611和第三延伸凸起621间隔预设距离交叠形成叉指结构，第二延伸凸起612和第四延伸凸起622间隔预设距离交叠形成叉指结构。
在本申请的第三种实现方式中，结合图5，在第一种实现方式的基础上，第二延伸凸起612靠近第二凸起框架62的端部朝向第一延伸凸起611的方向弯折延伸有第一附加凸起613，第三延伸凸起621靠近第一凸起框架61的端部朝向第四延伸凸起622的方向弯折延伸有第二附加凸起623；第一附加凸起613与第二凸起框架62平行设置并间隔预设距离交叠形成叉指结构，第二附加凸起623与第一凸起框架61平行设置并间隔预设距离交叠形成叉指结构。
在本申请的第四种实现方式中，结合图6，与第一种实现方式不同的是，第一延伸凸起611连接于第一凸起框架61的端部，第二延伸凸起612连接于第一凸起框架61的另一端的端部，第三延伸凸起621连接于第二凸起框架62且和第二凸起框架62的一端具有间距，第四延伸凸起622连接于第二凸起框架62的另一端的端部。因此，在本实现方式中，第一延伸凸起611和第三延伸凸起621间隔预设距离交叠形成叉指结构，第二延伸凸起612在其延伸方向上与第四延伸凸起622正对间隔设置。
在本申请的第五种实现方式中，结合图7，当第二延伸凸起612在其延伸方向上与第四延伸凸起622正对间隔设置时，叉指结构还包括连接第二延伸凸起612和第四延伸凸起622的连接凸起63，即本实现方式为：在第四种实现方式的基础上，第二延伸凸起612和第四延伸凸起622连接为一体且沿同一方向延伸。
进一步的，在前述各种实现方式中，预设距离为横向寄生声学波四分之一波长的整数倍。
进一步的，声学反射结构2可以为形成在衬底1内部的空腔或为形成在衬底1靠近底电极3的一侧的空腔或为形成在衬底1表面的布拉格反射镜，当声学反射结构为空腔时，底电极3沿薄膜体声波谐振器的厚度方向上的投影至少部分位于声学反射结构2外。其中图2a中声学反射结构2为形成在衬底1内部的空腔；图2b中声学反射结构2为形成在衬底1上方的空腔，此种情形下可以通过在衬底1与底电极3之间设置支撑层以形成空腔；图2c中声学反射结构2结构形成在衬底1表面的布拉格反射镜，该布拉格反射镜包括沿薄膜体声波谐振器厚度方向交替设置的低声学阻抗层21和高声学阻抗层22，其中低声学阻抗层的材料为氧化硅（SiO2）等，高声学阻抗层的材料为金属钨(W)、金属钨(Mo)、金属钌(Ru)、铱(Ir)等。
进一步的，声学反射结构2、底电极3、压电薄膜4和顶电极5沿薄膜体声波谐振器的厚度方向共同交叠重合形成的空间区域为谐振区，叉指型凸起框架6位于谐振区内且靠近谐振区的边缘设置。
进一步的，叉指型凸起框架6为金属材料或介电材料或金属材料和介电材料的复合材料。具体的可以为Al、Pt、Au、W、Mo、Ru、Ir、AlN和Si3N4中的一种或多种。
叉指型凸起框架的宽度范围可以为1nm～20000nm，例如50nm、500nm、5000nm、10000nm、15000nm等等；高度范围可以为1nm～10000nm，例如10nm、100nm、1000nm、3000nm、5000nm、7000nm、8000nm等等，构成叉指结构的两个凸起框架的宽度可以不同或相同。例如，靠近围合空间内侧的凸起框架的宽度大于靠近外侧的凸起框架的宽度，且靠近围合空间内侧的凸起框架的宽度和靠近外侧的凸起框架的宽度比值可以在1.1-2之间，例如1.3、1.5、1.7等等，当然，靠近围合空间内侧的凸起框架的宽度也可以小于靠近外侧的凸起框架的宽度，且靠近围合空间内侧的凸起框架的宽度和靠近外侧的凸起框架的宽度比值可以在0.5-0.95之间，如0.6、0.7、0.8等等。
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种薄膜体声波谐振器，该谐振器包括衬底、设置于所述衬底一侧的声学反射结构、叠设在所述声学反射结构一侧的底电极、覆盖所述底电极的压电薄膜以及叠设在所述压电薄膜的远离所述底电极侧的顶电极，其特征在于，所述顶电极的远离所述压电薄膜的一侧设置有叉指型凸起框架，所述叉指型凸起框架包括相对间隔设置的第一凸起框架和第二凸起框架，以及自所述第一凸起框架和所述第二凸起框架分别相向延伸且彼此交叠形成的至少一对叉指结构，每一所述叉指结构包括沿交叠方向间隔预设距离的两个叉指。
  2. 如权利要求1所述的薄膜体声波谐振器，其特征在于，所述叉指结构包括连接于所述第一凸起框架靠近所述第二凸起框架一侧且间隔设置的第一延伸凸起和第二延伸凸起，连接于所述第二凸起框架靠近所述第一凸起框架一侧且间隔设置的第三延伸凸起和第四延伸凸起，其中所述第一延伸凸起与所述第三延伸凸起之间间隔预设距离并交叠形成叉指结构；所述第二延伸凸起与所述第四延伸凸起之间间隔设置。
  3. 如权利要求2所述的薄膜体声波谐振器，其特征在于，所述第二延伸凸起在其延伸方向上与所述第四延伸凸起正对间隔设置或所述第二延伸凸起与所述第四延伸凸起之间间隔预设距离并交叠形成叉指结构。
  4. 如权利要求3所述的薄膜体声波谐振器，其特征在于，当所述第二延伸凸起在其延伸方向上与所述第四延伸凸起正对间隔设置时，所述叉指结构还包括连接所述第二延伸凸起和所述第四延伸凸起的连接凸起。
  5. 如权利要求3所述的薄膜体声波谐振器，其特征在于，所述第二延伸凸起靠近所述第二凸起框架的端部朝向所述第一延伸凸起的方向弯折延伸有第一附加凸起，所述第三延伸凸起靠近所述第一凸起框架的端部朝向所述第四延伸凸起的方向弯折延伸有第二附加凸起；所述第一附加凸起与所述第二凸起框架平行设置并间隔预设距离交叠形成叉指结构，所述第二附加凸起与所述第一凸起框架平行设置并间隔预设距离交叠形成叉指结构。
  6. 如权利要求3所述的薄膜体声波谐振器，其特征在于，所述第一延伸凸起和所述第二延伸凸起分别连接于所述第一凸起框架沿其延伸方向的相对两端部，所述第三延伸凸起和所述第四延伸凸起分别连接于所述第二凸起框架沿其延伸方向的靠近端部的位置处并位于所述第一凸起框架、所述第一延伸凸起和所述第二延伸凸起围成的空间内。
  7. 如权利要求1-6任一项所述的薄膜体声波谐振器，其特征在于，所述预设距离为横向寄生声学波四分之一波长的整数倍。
  8. 如权利要求1所述的薄膜体声波谐振器，其特征在于，所述声学反射结构为形成在所述衬底内部的空腔或为形成在所述衬底靠近所述底电极的一侧的空腔或为形成在所述衬底表面的布拉格反射镜，当所述声学反射结构为空腔时，所述底电极沿所述薄膜体声波谐振器的厚度方向上的投影至少部分位于所述声学反射结构外。
  9. 如权利要求1所述的薄膜体声波谐振器，其特征在于，所述声学反射结构、底电极、压电薄膜和顶电极沿所述薄膜体声波谐振器的厚度方向共同交叠重合形成的空间区域为谐振区，所述叉指型凸起框架位于所述谐振区内且靠近所述谐振区的边缘设置。
  10. 如权利要求1所述的薄膜体声波谐振器，其特征在于，所述叉指型凸起框架为金属材料或介电材料或金属材料和介电材料的复合材料。
PCT/CN2022/110237 2022-07-07 2022-08-04 一种薄膜体声波谐振器 WO2024007404A1 (zh)

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