WO2022007246A1 - 谐振器 - Google Patents

谐振器 Download PDF

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Publication number
WO2022007246A1
WO2022007246A1 PCT/CN2020/123433 CN2020123433W WO2022007246A1 WO 2022007246 A1 WO2022007246 A1 WO 2022007246A1 CN 2020123433 W CN2020123433 W CN 2020123433W WO 2022007246 A1 WO2022007246 A1 WO 2022007246A1
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WIPO (PCT)
Prior art keywords
electrode
longitudinal
film
piezoelectric
region
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PCT/CN2020/123433
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English (en)
French (fr)
Inventor
窦韶旭
吕丽英
杨帅
吴一雷
韩琦
吴珂
王超
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AAC Technologies Holdings Shenzhen Co Ltd
AAC Technologies Holdings Nanjing Co Ltd
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AAC Acoustic Technologies Shenzhen Co Ltd
AAC Technologies Holdings Nanjing Co Ltd
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Publication of WO2022007246A1 publication Critical patent/WO2022007246A1/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 elements; 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

Definitions

  • the invention relates to the technical field of resonators, in particular to a thin-film bulk acoustic wave resonator.
  • the resonator includes a substrate, a first electrode, a piezoelectric film and a second electrode stacked along a first direction, and a longitudinal acoustic wave reflector is arranged between the substrate and the first electrode; the longitudinal acoustic wave
  • the area enclosed by the inner edge of the orthographic projection of the reflector along the first direction is the resonance area
  • the area enclosed by the projection of the second electrode along the first direction is the excitation area
  • longitudinal acoustic waves will be generated in the excitation area and transverse sound waves.
  • the composite film is discontinuous in the excitation region and outside the excitation region, and when the transverse acoustic wave propagates outward to the side of the second electrode and the edge of the resonance region, an acoustic wave scattering effect occurs each, resulting in the generation of a large number of transverse waves.
  • Superimposed resonance, and a large amount of acoustic wave energy enters the substrate to form dissipation, resulting in a significant reduction in the Q value of the anti-resonance point.
  • An object of the present invention is to provide a resonator with reduced energy loss and increased Q value.
  • the present invention provides a resonator, which includes a base, a composite film disposed above the base along a first direction, and a longitudinal acoustic wave reflector disposed on the side of the composite film close to the base;
  • the composite film comprises a first electrode, a piezoelectric functional film and a second electrode arranged in sequence along the first direction, the first electrode being arranged on the substrate and the longitudinal acoustic wave reflector;
  • the piezoelectric functional film includes a longitudinal piezoelectric film and a longitudinal non-piezoelectric film, the longitudinal piezoelectric film is disposed on the side of the first electrode away from the substrate, and the longitudinal non-piezoelectric film includes a longitudinal non-piezoelectric film surrounding the longitudinal direction.
  • the piezoelectric film is disposed on the main body portion of the first electrode away from the substrate, and a ring-shaped convex ring protruding from the main body portion away from the first electrode toward the second electrode
  • the area enclosed by the orthographic projection of the inner side of the convex ring to the main body along the first direction is a resonance area, and the area where the resonator is located outside the resonance area is a non-resonance area; the Both the first electrode and the second electrode completely cover the resonance region, and the part of the second electrode located in the non-resonance region is disposed on the side of the convex ring away from the main body; the longitudinal pressure
  • the electric film is located in the resonance area; the acoustic impedance of the part of the resonator located in the resonance area is different from the acoustic impedance of the part of the resonator located in the non-resonance area, and the first electrode, the The acoustic impedances of the piezoelectric
  • the second electrode includes a first part located in the resonant region and a second part located in the non-resonant region and sleeved on a side of the first part away from the main body part, the first parts are stacked is arranged on the main body part and covered on the vertical piezoelectric film, the convex ring surrounds the first part and the inner side surface of the convex ring abuts on the first part; the second part is provided with on the side of the protruding ring away from the main body.
  • the orthographic projection of the longitudinal piezoelectric film to the convex ring along the first direction completely falls within the area enclosed by the inner side surface of the convex ring.
  • the part of the composite film that falls within the region enclosed by the outer side surface of the longitudinal piezoelectric film along the first direction forms an excitation region, and the excitation region is located in the resonance region.
  • the longitudinal piezoelectric film has a piezoelectric coefficient along the first direction, and the piezoelectric coefficient of the longitudinal non-piezoelectric film along the first direction is zero or smaller than the longitudinal piezoelectric film along the first direction.
  • the piezoelectric coefficient in the first direction is described.
  • the longitudinal acoustic wave reflector is a cavity structure formed by a side of the substrate close to the first electrode that is recessed in a direction away from the first electrode.
  • the longitudinal acoustic wave reflector is a Bragg acoustic reflector disposed on a side of the substrate close to the first electrode, and the first electrode is disposed on a side of the Bragg acoustic reflector away from the substrate.
  • the longitudinal acoustic wave reflector includes a first film layer and a second film layer stacked along the first direction, the acoustic impedance of the first film layer is smaller than the acoustic impedance of the second film layer, so The first film layer and the second film layer together form the Bragg acoustic mirror.
  • the first film layer includes at least two
  • the second film layer includes at least two
  • the first film layer and the second film layer are alternately stacked in sequence along the first direction.
  • the orthographic projection of the area enclosed by the inner surface of the convex ring to the longitudinal acoustic wave reflector along the first direction falls within the range of the longitudinal acoustic wave reflector.
  • the longitudinal non-piezoelectric film includes a main body part surrounding the longitudinal piezoelectric film and disposed on the side of the first electrode away from the substrate;
  • the electrode protrudes and extends in a ring-shaped convex ring, the second electrode is arranged on the main body and is covered on the longitudinal piezoelectric film, the inner surface of the convex ring is in contact with the second electrode; the inner surface of the convex ring is along the first direction
  • the area enclosed by the orthographic projection to the main body is the resonant area, and the area where the resonator is located outside the resonant area is the non-resonant area; both the first electrode and the second electrode completely cover the resonant area, and the second electrode is located in the non-resonant area.
  • the part is arranged on the side of the convex ring away from the main body; the acoustic impedance of the part of the composite film in the resonant region is different from that of the part of the composite film in the non-resonant region, and the first electrode, the piezoelectric functional film and the second electrode
  • the acoustic impedance of the part located in the resonance zone is constant; in the above structure, the arrangement of the convex ring causes the increase of the acoustic impedance of the position where the convex ring is arranged by the composite film, so that the convex ring acts as a transverse acoustic wave reflector , during the outward propagation of the transverse sound wave, only one sound wave scattering effect occurs at the transverse sound wave reflector, and the transverse sound wave reflector mainly reflects the sound wave to the transverse sound wave.
  • the transverse wave resonance is less and weaker, and the Q value of the anti-resonance point is greatly improved.
  • FIG. 1 is a schematic three-dimensional structure diagram of Embodiment 1 of the resonator of the present invention
  • FIG. 2 is an exploded view of a partial three-dimensional structure of the first embodiment of the resonator of the present invention
  • Fig. 3 is the sectional view along A-A line of Fig. 1;
  • FIG. 4 is an exploded view of a partial three-dimensional structure of the second embodiment of the resonator of the present invention.
  • FIG. 5 is a schematic cross-sectional view of Embodiment 2 of the resonator of the present invention.
  • the shape of the electrodes in the resonator is mostly apodized polygons, and the specific shape of the electrodes in the resonator can be set according to the actual design.
  • the shapes of the resonator electrodes in the first embodiment shown in Figs. 1-3 and the resonator electrodes in the second embodiment shown in Figs. 4-5 are both square, and the setting of the shapes does not limit the shape of the resonator electrodes in this patent.
  • Apodized polygons and other shapes cannot be used.
  • the resonator of the present invention is described below through two embodiments:
  • the present invention provides a resonator 100, which includes a substrate 1, a composite film 2 disposed above the substrate 1 along a first direction (ie, the X-axis direction), and a composite film 2 disposed on the substrate 1 and the longitudinal acoustic wave reflector 3 between the composite film 2 , wherein the first direction is the thickness direction of the resonator 100 .
  • the composite film 2 includes a first electrode 21 , a piezoelectric functional film 22 and a second electrode 23 arranged in sequence along the first direction, and the first electrode 21 is arranged on the substrate 1 and the longitudinal acoustic wave reflector 3 and above.
  • the arrangement of two adjacent structures is not limited.
  • the composite film 2 is stacked on the surface of the substrate 1, and the first electrode 21 is stacked on the surface of the substrate 1.
  • the substrate 1 is covered on the longitudinal acoustic wave reflector 3, the piezoelectric functional film 22 is stacked on the surface of the first electrode 21, and the second electrode 23 is stacked on the pressure.
  • the electrical functional film 22 is far away from the surface of the first electrode 21; of course, in other embodiments, other film layer structures are added between two adjacent structures, so that the two structures are not directly stacked on each other.
  • between the first electrode and the piezoelectric functional film, or between the piezoelectric functional film and the first electrode It is also feasible to add other film layer structures between the two electrodes.
  • the longitudinal acoustic wave reflector 3 is a cavity structure formed by a side of the substrate 1 close to the first electrode 21 that is recessed in a direction away from the first electrode 21 , and the first electrode 21 completely covers the cavity structure.
  • the piezoelectric functional film 22 includes a vertical piezoelectric film 221 and a vertical non-piezoelectric film 222 .
  • the vertical piezoelectric film 221 is disposed on the first electrode 21
  • the vertical non-piezoelectric film 222 is disposed around the outer periphery of the vertical piezoelectric film 221 and disposed on the The first electrode 21 is away from the substrate 1 side.
  • the longitudinal piezoelectric film 221 is stacked on the surface of the first electrode 21 away from the substrate 1 .
  • the electric film 222 is stacked on the surface of the first electrode 21 away from the substrate 1; the piezoelectric functional film 22 has a piezoelectric coefficient along the first direction, more specifically, the longitudinal piezoelectric film 221 has a piezoelectric coefficient along the first direction, and the piezoelectric coefficient of the longitudinal non-piezoelectric film 222 along the first direction is zero or smaller than the piezoelectric coefficient of the longitudinal piezoelectric film 221 along the first direction. Electric coefficient.
  • the longitudinal non-piezoelectric film 222 includes a main body portion 2221 surrounding the longitudinal piezoelectric film 221 and stacked on the side of the first electrode 21 away from the substrate 1 , and a main body portion 2221 away from the substrate 1 .
  • One side of the first electrode 21 is a convex ring 2222 that protrudes and extends toward the second electrode 23 .
  • the second electrode 23 is stacked on the main body portion 2221 and covers the vertical piezoelectric film 221 .
  • the inner side surface 2220 of the convex ring 2222 surrounds the second electrode 23 and abuts against the second electrode 23 to serve as a transverse acoustic wave reflector 4 .
  • the specific shape of the convex ring 2222 is not limited.
  • the convex ring 2222 has a closed annular structure; of course, in other embodiments, the convex ring is also It can be in the form of an open ring structure.
  • the arrangement of the convex ring 2222 effectively increases the overall thickness of the longitudinal non-piezoelectric film 222 along the first direction at the position where the convex ring 2222 is disposed, so that the longitudinal non-piezoelectric film 222 is provided with
  • the acoustic impedance of the portion of the electric film 222 where the convex ring 2222 is provided is greater than the acoustic impedance of the portion where the convex ring 2222 is not provided, which provides conditions for the convex ring 2222 to act as the transverse acoustic wave reflector 4 .
  • the longitudinal piezoelectric film 221 and the longitudinal non-piezoelectric film 222 are respectively made of two different materials; or, the longitudinal piezoelectric film 221 and the longitudinal non-piezoelectric film 222 are respectively Two kinds of materials with different crystal properties are made of the same material; further, the longitudinal non-piezoelectric film 222 is a composite structure composed of two or more layers of films with different materials.
  • the area enclosed by the orthographic projection of the inner side surface 2220 of the convex ring 2222 to the main body portion 2221 along the first direction is the resonance area 10, and the resonator 100 is located in the resonance area
  • the area outside 10 is the non-resonant region 20 .
  • Both the first electrode 21 and the second electrode 23 completely cover the resonance region 10 , and the part of the second electrode 23 located in the non-resonance region 20 is stacked on the convex ring 2222 away from the main body one side of the portion 2221 ; the longitudinal piezoelectric film 221 is located in the resonance region 10 .
  • the second electrode 23 includes a first portion 231 located in the resonant region 10 and a second portion 232 located in the non-resonant region 20 and sleeved on the side of the first portion 231 away from the main body.
  • the first part 231 is disposed on the main body part 2221 and covered on the vertical piezoelectric film 221
  • the convex ring 2222 surrounds the first part 231 and the inner side surface 2220 of the convex ring 2222 abuts
  • the first part 231 that is, the inner side surface 2220 of the convex ring 2222 abuts against the first part 231
  • the second part 232 is disposed on the side of the convex ring 222 away from the main body part 2221; specifically
  • the first part 231 is stacked on the surface of the main body part 2221 away from the piezoelectric functional film 22
  • the second part 232 is stacked on the surface of the convex ring 222 away from the main body part 2221 .
  • the resonance region 10 is composed of an excitation region 101 and a non-excitation region 102, wherein the excitation region 101 is located by the composite film 2 falling on the outer side surface 2210 of the longitudinal piezoelectric film 221 along the first direction.
  • the non-excited area 102 is formed around the outer periphery of the excitation area 101 , in fact, the non-excited area 102 is the difference between the resonance area 10 and the excitation area 101 .
  • the acoustic impedance of the part of the resonator 100 located in the resonant region 10 is different from the acoustic impedance of the part of the resonator 100 located in the non-resonant region 20, so that the acoustic impedance of the resonant region 10 is different from that of the non-resonant region 20.
  • the acoustic impedances between the resonant regions 20 are discontinuous, and the acoustic impedances of the parts of the composite film 2 located in the resonant region 10 are substantially constant.
  • the first electrodes 21, The acoustic impedance of the piezoelectric functional film 22 and the portion of the second electrode 23 located in the resonance region 10 is substantially constant.
  • the acoustic impedance of each film layer of the composite film 2 located in the resonant region 10 is substantially constant.
  • the first electrode 21 , the piezoelectric functional film 22 , the The acoustic impedance of the portion of the second electrode 23 located in the resonance region 10 is substantially constant.
  • the acoustic impedance of the portion of the composite film 2 located in the excitation region 101 remains unchanged, and the acoustic impedance of the portion of the composite film 2 located in the non-excitation region 102 is within 30% of the acoustic impedance of the portion of the composite film 2 located in the excitation region 101.
  • the acoustic impedance of each film layer of the composite film 2 located in the resonance region 10 is substantially constant.
  • the acoustic impedance of the longitudinal non-piezoelectric film 222 in the non-excited region 102 is equivalent to 70% to 130% of the acoustic impedance of the longitudinal piezoelectric film 221 .
  • the piezoelectric functional film 22 is in the resonance region 10 .
  • the acoustic impedance of the inner part is approximately constant.
  • the acoustic impedances of the first electrode 21 and the second electrode 23 in the excitation region 101 and the non-excitation region 102 satisfy the above relationship, it can also be considered that the first electrode 21 and the second electrode 23 are in the resonance region 10 .
  • the acoustic impedance of the part is roughly constant. More specifically, the acoustic impedance of the portion of the composite film 2 located in the resonant region 10 is greater than the acoustic impedance of the portion of the composite film 2 located in the non-resonant region 20 .
  • the part of the composite membrane 2 located in the excitation region 101 will excite the longitudinal acoustic wave S1 (for the working mode acoustic wave) and the transverse acoustic wave S2 (for the non-working mode acoustic wave)
  • the longitudinal acoustic wave S1 is confined in the composite membrane 2 by the upper and lower reflection interfaces, while the transverse acoustic wave S2 propagates laterally outward from the interior of the composite membrane 2 along the first direction perpendicular to the first direction.
  • the acoustic impedance of the non-excitation area 102 is the same as that of the excitation area 101, when the transverse acoustic wave S2 passes through the interface between the excitation area 101 and the non-excitation area 102, all the Described transverse acoustic wave S2 produces sound wave scattering effect, effectively reduces the sound wave energy of transverse acoustic wave S2 The phenomenon of scattering loss occurs, it is ensured that most of the acoustic wave energy of described transverse acoustic wave S2 transmits and propagates forward;
  • the acoustic impedance of 102 is smaller than the acoustic impedance of the non-resonant region 20.
  • the transverse acoustic wave S2 passes through the interface between the non-excited region 102 and the non-resonant region 20, the transverse acoustic wave S2 is larger than that of the non-resonant region 20.
  • Part of the acoustic wave energy is mainly returned to the resonant area 10 through acoustic wave reflection and propagates, and only a small part of the energy will have the acoustic wave scattering effect, which effectively prevents most of the transverse acoustic waves S2 from entering the non-resonant area 20 to form energy loss.
  • the width of the non-excited region 102 is controlled to be small enough, the transverse incident wave and the reflected wave will not form standing wave resonance in the non-excited region 102 to avoid the formation of the parasitic mode of the transverse acoustic wave S2, The sound wave energy of the transverse sound wave S2 is further guaranteed.
  • the orthographic projection of the longitudinal piezoelectric film 221 to the convex ring 2222 along the first direction falls on the inner side of the convex ring 2222 . 2220; the orthographic projection of the area enclosed by the inner side surface 2220 of the convex ring 2222 to the longitudinal acoustic wave reflector 3 completely falls on the longitudinal acoustic wave reflector 3 along the first direction. within the range.
  • FIG. 4 is a schematic diagram of another embodiment of the structure shown in FIG. 2.
  • the resonator 100a of the second embodiment is the sound-emitting device of the first embodiment.
  • the structure of the two is basically the same, and the same parts will not be repeated one by one, but the main differences of the resonator 100a of the second embodiment are:
  • the longitudinal acoustic wave reflector 3a is a Bragg acoustic reflector disposed on the side of the substrate 1a close to the first electrode 21a, and the first electrode 21a is disposed on the side of the Bragg acoustic reflector away from the substrate 1a; more specifically, the first electrodes 21a are stacked on top of each other.
  • the first electrode and the Bragg acoustic mirror are not directly stacked with each other. It is also feasible to add other film layer structures between the electrodes and the Bragg acoustic mirror.
  • the longitudinal acoustic wave reflector 3a includes a first film layer 31a and a second film layer 32a stacked along the first direction (that is, the thickness direction of the resonator 100a, the X-axis direction in the figure).
  • the first film layer 31a The acoustic impedance is smaller than the acoustic impedance of the second film layer 32a, and the first film layer 31a and the second film layer 32a together form a Bragg acoustic mirror.
  • the first film layer 31a and the second film layer 32a each include at least two, and the specific number of the above two can be set according to actual needs.
  • the first film layer 31a includes two
  • the second film layer 32a includes two
  • the first film layer 31a and the second film layer 32a are alternately stacked along the first direction.
  • the longitudinal non-piezoelectric film includes a main body part surrounding the longitudinal piezoelectric film and disposed on the side of the first electrode away from the substrate;
  • the electrode protrudes and extends in a ring-shaped convex ring, the second electrode is arranged on the main body and is covered on the longitudinal piezoelectric film, the inner surface of the convex ring is in contact with the second electrode; the inner surface of the convex ring is along the first direction
  • the area enclosed by the orthographic projection to the main body is the resonant area, and the area where the resonator is located outside the resonant area is the non-resonant area; both the first electrode and the second electrode completely cover the resonant area, and the second electrode is located in the non-resonant area.
  • the part is arranged on the side of the convex ring away from the main body; the acoustic impedance of the part of the composite film in the resonant region is different from that of the part of the composite film in the non-resonant region, and the first electrode, the piezoelectric functional film and the second electrode
  • the acoustic impedance of the part located in the resonance region is substantially constant; in the above structure, the arrangement of the convex ring causes the increase of the acoustic impedance of the position where the convex ring is arranged by the composite film, so that the convex ring is used as a transverse acoustic wave reflection
  • the transverse acoustic wave propagates outward, only one acoustic wave scattering effect occurs at the transverse acoustic wave reflector, and the transverse acoustic wave reflector mainly reflects the transverse acoustic wave. Under the action, the transverse wave resonance is less and weaker, and the

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Abstract

一种谐振器（100），包括基底（1）、复合膜（2）和纵向声波反射器（3），复合膜（2）包括沿第一方向依次设置的第一电极（21）、压电功能膜（22）和第二电极（23），第一电极（21）设置于基底（1）和纵向声波反射器（3）上；压电功能膜（22）包括纵向压电膜（221）和纵向非压电膜（222），纵向非压电膜（222）包括主体部（2221）和由主体部延伸的呈环状的凸环（2222）；凸环（2222）的内侧面沿第一方向向主体部（2221）的正投影所围成的区域为谐振区（10），谐振器（100）位于谐振区（10）外的区域为非谐振区（20）；第一电极（21）、第二电极（23）均完全覆盖谐振区（10），且第二电极（23）位于非谐振区（20）的部分设置于凸环（2222）远离主体部（2221）的一侧；谐振器（100）在谐振区（10）内和在非谐振区（20）内的声阻抗相异，且第一电极（21）、压电功能膜（22）和第二电极（23）位于谐振区（10）内的部分的声阻抗均是大致不变的。

Description

谐振器 技术领域
本发明涉及谐振器技术领域，尤其涉及一种薄膜体声波谐振器。
 背景技术
随着智能设备的日益增多，以及物联网和5G技术的不断普及，对高性能滤波器和多功器的需求越来越大。声学谐振器作为滤波器和多功器的重要组成部分，一直是近年来研究的重点对象。
相关技术中，谐振器包括沿第一方向叠设的基底、第一电极、压电膜以及第二电极，所述基底和所述第一电极之间设置有纵向声波反射器；所述纵向声波反射器沿所述第一方向的正投影内边缘所包围的区域为谐振区，所述第二电极沿所述第一方向的投影所包围的区域为激发区，在激发区内会产生纵向声波和横向声波。
 技术问题
然而，相关技术中，复合膜在激发区和激发区外不连续，横向声波向外传播到第二电极的侧边和谐振区的边缘时，各发生一次声波散射效应，导致产生大量横向波的叠加谐振，且大量声波能量进入衬底形成耗散，造成反谐振点的Q值大幅降低。
因此，实有必要提供一种新的谐振器解决上述技术问题。
 技术解决方案
本发明的目的在于提供一种减少能量损失且Q值增大的谐振器。
为了达到上述目的，本发明提供一种谐振器，其包括基底、沿第一方向设置于所述基底上方的复合膜以及设置于所述复合膜靠近所述基底一侧的纵向声波反射器；所述复合膜包括沿所述第一方向依次设置的第一电极、压电功能膜以及第二电极，所述第一电极设置于所述基底和所述纵向声波反射器之上；
所述压电功能膜包括纵向压电膜以及纵向非压电膜，所述纵向压电膜设置于所述第一电极远离所述基底一侧，所述纵向非压电膜包括环绕所述纵向压电膜且设置于所述第一电极远离所述基底一侧的主体部以及由所述主体部远离所述第一电极一侧向所述第二电极凸出延伸的呈环状的凸环；所述凸环的内侧面沿所述第一方向向所述主体部的正投影所围成的区域为谐振区，所述谐振器位于所述谐振区外的区域为非谐振区；所述第一电极和所述第二电极均完全覆盖所述谐振区，且所述第二电极位于所述非谐振区的部分设置于所述凸环远离所述主体部的一侧；所述纵向压电膜位于所述谐振区内；所述谐振器位于所述谐振区的部分的声阻抗与所述谐振器位于所述非谐振区的部分的声阻抗相异，且所述第一电极、所述压电功能膜和所述第二电极位于所述谐振区内的部分的声阻抗均是大致不变的。
优选的，所述第二电极包括位于所述谐振区内的第一部分和位于所述非谐振区并套设于所述第一部分远离所述主体部一侧的第二部分，所述第一部分叠设于所述主体部并盖设于所述纵向压电膜之上，所述凸环环绕所述第一部分且所述凸环的内侧面抵接于所述第一部分；所述第二部分设置于所述凸环远离所述主体部的一侧。
优选的，所述纵向压电膜沿所述第一方向向所述凸环的正投影完全落在所述凸环的内侧面所围成的区域内。
优选的，所述复合膜沿所述第一方向落在所述纵向压电膜的外侧面所围成的区域内的部分形成激发区，所述激发区位于所述谐振区内。
优选的，所述纵向压电膜具有沿所述第一方向的压电系数，所述纵向非压电膜沿所述第一方向的压电系数为零或小于所述纵向压电膜沿所述第一方向的压电系数。
优选的，所述纵向声波反射器为由所述基底靠近所述第一电极一侧向远离所述第一电极的方向凹陷形成的空腔结构。
优选的，所述纵向声波反射器为设置于所述基底靠近所述第一电极一侧的布拉格声反射镜，所述第一电极设置于所述布拉格声反射镜远离所述基底一侧。
优选的，所述纵向声波反射器包括沿所述第一方向叠设的第一膜层和第二膜层，所述第一膜层的声阻抗小于所述第二膜层的声阻抗，所述第一膜层与所述第二膜层共同形成所述布拉格声反射镜。
优选的，所述第一膜层包括至少两个，所述第二膜层包括至少两个，所述第一膜层和所述第二膜层沿所述第一方向依次交替叠设。
优选的，所述凸环的内侧面所围成的区域沿所述第一方向向所述纵向声波反射器的正投影落在所述纵向声波反射器的范围内。
 有益效果
与相关技术相比，本发明的谐振器中，纵向非压电膜包括环绕纵向压电膜且设置于第一电极远离基底一侧的主体部以及由主体部远离第一电极一侧向第二电极凸出延伸的呈环状的凸环，第二电极设置于主体部并盖设纵向压电膜之上，凸环的内侧面抵接于第二电极；凸环的内侧面沿第一方向向主体部的正投影所围成的区域为谐振区，谐振器位于谐振区外的区域为非谐振区；第一电极和第二电极均完全覆盖谐振区，且第二电极位于非谐振区的部分设置于凸环远离主体部的一侧；复合膜位于谐振区的部分的声阻抗与复合膜位于非谐振区的部分的声阻抗相异，且第一电极、压电功能膜和第二电极位于谐振区内的部分的声阻抗均是不变的；上述结构中，通过凸环的设置，引起了复合膜设置该凸环的位置的声阻抗增加，从而使得该凸环作为横向声波反射器，在横向声波向外传播过程中，只在横向声波反射器处发生一次声波散射效应，且横向声波反射器对横向声波主要发生的是声波反射作用，因此在纵向、横向声波反射器的共同作用下，横向波谐振更少更弱，反谐振点的Q值大幅提高。
 附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图，其中：
图1为本发明谐振器实施方式一的立体结构示意图；
图2为本发明谐振器实施方式一的部分立体结构分解图；
图3为图1沿A-A线的剖视图；
图4为本发明谐振器实施方式二的部分立体结构分解图；
图5为本发明谐振器实施方式二的截面示意图。
 本发明的实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅是本发明的一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其它实施例，都属于本发明保护的范围。
首先，需要说明的是，在实际应用中，谐振器中电极的形状多为变迹多边形，而谐振器中电极具体的形状可以根据实际设计的情况进行具体的设置，比如，下面所提及到的图1-3所示的实施方式一的谐振器电极以及图4-5所示实施方式二的谐振器电极的形状均为正方形，该形状的设置并非限定了本专利中的谐振器电极形状不能用变迹多边形以及其他形状。下面通过两个实施方式对本发明的谐振器进行展开描述：
实施方式一
请参阅图1-3所示，本发明提供一种谐振器100，其包括基底1、沿第一方向（即X轴方向）设置于所述基底1上方的复合膜2以及设置于所述基底1和所述复合膜2之间的纵向声波反射器3，其中，所述第一方向为所述谐振器100的厚度方向。
所述复合膜2包括沿所述第一方向依次设置的第一电极21、压电功能膜22以及第二电极23，所述第一电极21设置于所述基底1和所述纵向声波反射器3之上。
相邻两个结构相互之间的设置方式是不限的，比如，在本实施方式一中，所述复合膜2叠设于所述基底1的表面上，所述第一电极21叠设于所述基底1并盖设于所述纵向声波反射器3之上，所述压电功能膜22叠设于所述第一电极21的表面上，所述第二电极23叠设于所述压电功能膜22远离所述第一电极21的表面上；当然，在其他实施方式中，在相邻两个结构之间增设其它的膜层结构，使得两者相互之间不直接叠设也是可行的，譬如，可以根据实际设计的需要，复合膜与基底之间增加其它的膜层结构也是可行，同样道理，而在第一电极与压电功能膜之间、或在压电功能膜与第二电极之间增设其它的膜层结构也是可行的。
具体的，所述纵向声波反射器3为由所述基底1靠近所述第一电极21一侧向远离所述第一电极21的方向凹陷形成的空腔结构，所述第一电极21完全覆盖所述空腔结构。
所述压电功能膜22包括纵向压电膜221以及纵向非压电膜222。
在本实施方式一中，所述纵向压电膜221设置于所述第一电极21之上的，所述纵向非压电膜222环绕所述纵向压电膜221外周缘设置且设置于所述第一电极21远离所述基底1一侧，具体的，本实施方式中，所述纵向压电膜221叠设于所述第一电极21远离所述基底1的表面上，所述纵向非压电膜222叠设于所述第一电极21远离所述基底1的表面上；所述压电功能膜22具有沿所述第一方向的压电系数，更具体的，所述纵向压电膜221具有沿所述第一方向的压电系数，所述纵向非压电膜222沿所述第一方向的压电系数为零或小于所述纵向压电膜221沿所述第一方向的压电系数。
进一步的，所述纵向非压电膜222包括环绕所述纵向压电膜221且叠设于所述第一电极21远离所述基底1一侧的主体部2221以及由所述主体部2221远离所述第一电极21一侧向所述第二电极23凸出延伸的凸环2222，所述第二电极23叠设于所述主体部2221并盖设所述纵向压电膜221之上，所述凸环2222的内侧面2220环绕所述第二电极23且抵接于所述第二电极23以充当横向声波反射器4。
值得一提的是，所述凸环2222具体的形状是不限的，在本实施方式一中，所述凸环2222呈封闭的环状结构；当然，在其他的实施方式中，凸环也可以呈开口的环状结构。
上述结构中，通过所述凸环2222的设置，有效地增加了所述纵向非压电膜222设置所述凸环2222的位置沿所述第一方向的整体厚度，从而使得所述纵向非压电膜222设置凸环2222的部分的声阻抗大于不设置凸环2222的部分的声阻抗，为所述凸环2222充当所述横向声波反射器4提供了条件。
更进一步的，所述纵向压电膜221和所述纵向非压电膜222分别为两种不同的材料制成；或，所述纵向压电膜221和所述纵向非压电膜222分别为两种结晶特性不同的同种材料制成；更进一步的，所述纵向非压电膜222为材料不同的两层或多层膜组成的复合结构。
需要特别说明的是，所述凸环2222的内侧面2220沿所述第一方向向所述主体部2221的正投影所围成的区域为谐振区10，所述谐振器100位于所述谐振区10外的区域为非谐振区20。
所述第一电极21和所述第二电极23均完全覆盖所述谐振区10，且所述第二电极23位于所述非谐振区20的部分叠设于所述凸环2222远离所述主体部2221的一侧；所述纵向压电膜221位于所述谐振区10内。
进一步的，所述第二电极23包括位于所述谐振区10内的第一部分231和位于所述非谐振区20并套设于所述第一部分231远离所述主体部一侧的第二部分232，所述第一部分231设置于所述主体部2221并盖设于所述纵向压电膜221之上，所述凸环2222环绕所述第一部分231且所述凸环2222的内侧面2220抵接于所述第一部分231，即所述凸环2222的内侧面2220抵接于所述第一部分231；所述第二部分232设置于所述凸环222远离所述主体部2221的一侧；具体的，所述第一部分231叠设于所述主体部2221远离所述压电功能膜22的表面上，所述第二部分232叠设于所述凸环222远离所述主体部2221的表面上。
所述谐振区10由激发区101和非激发区102共同组成，其中，所述激发区101由所述复合膜2沿所述第一方向落在所述纵向压电膜221的外侧面2210所围成的区域的部分形成，而所述非激发区102围绕所述激发区101外周侧设置，实际上，所述非激发区102为所述谐振区10与所述激发区101之差。所述谐振器100位于所述谐振区10的部分的声阻抗与所述谐振器100位于所述非谐振区20的部分的声阻抗相异，使得所述谐振区10 的声阻抗与所述非谐振区20之间的声阻抗之间不连续，且所述复合膜2的各个膜层位于所述谐振区10的部分的声阻抗是大致不变的，具体的，所述第一电极21、所述压电功能膜22、所述第二电极23位于所述谐振区10内的部分的声阻抗是大致不变的。值得说明的是，所述复合膜2的各个膜层位于所述谐振区10的部分的声阻抗是大致不变的，本实施方式中所述第一电极21、所述压电功能膜22、所述第二电极23位于所述谐振区10内的部分的声阻抗均是大致不变的。具体的，复合膜2位于激发区101内部分的声阻抗不变，复合膜2位于非激发区102内部分的声阻抗相对于复合膜2位于激发区101内部分的声阻抗上下浮动30%以内均可以认为复合膜2的各个膜层位于谐振区10的部分的声阻抗是大致不变的。在本实施方式中，纵向非压电膜222在非激发区102内部分的声阻抗相当于纵向压电膜221的声阻抗的70%到130%均可以认为压电功能膜22在谐振区10内的部分的声阻抗是大致不变的。同样的，第一电极21和第二电极23在激发区101和非激发区102内的声阻抗满足上述关系的情况下，也可以认为第一电极21和第二电极23在谐振区10内的部分的声阻抗是大致不变的。更具体的，所述复合膜2位于所述谐振区10的部分的声阻抗大于所述复合膜2位于所述非谐振区20的部分的声阻抗。
上述结构中，当谐振器100工作时，在所述复合膜2位于所述激发区101内的部分会激发纵向声波S1（为工作模态声波）和横向声波S2（为非工作模态声波），纵向声波S1被上下两个反射界面约束在所述复合膜2内，而横向声波S2则会从所述复合膜2内部沿垂直所述第一方向向外横向传播。
由于所述非激发区102的声阻抗与所述激发区101的声阻抗相同，当所述横向声波S2经过所述激发区101和所述非激发区102之间的分界面时，避免了所述横向声波S2发生声波散射效应，有效地降低横向声波S2的声波能量发生散射损耗现象，保证了所述横向声波S2的大部分声波能量发生透射并向前传播； 而又由于所述非激发区102的声阻抗小于所述非谐振区20的声阻抗，当所述横向声波S2经过所述非激发区102和所述非谐振区20之间的分界面时，但所述横向声波S2的大部分声波能量主要通过声波反射作用返回所述谐振区10内并传播，仅有小部分能量会发生声波散射效应，有效地避免了大部分的横向声波S2进入所述非谐振区20从而形成能量损耗；在实际应用中，当控制所述非激发区102的宽度足够小，横向入射波和反射波便不会在所述非激发区102形成驻波谐振，避免形成横向声波S2的寄生模态，更进一步地保证所述横向声波S2的声波能量。
上述结构中，在横向声波S2向外传播过程中，只在所述凸环2222的内侧面2220处发生一次声波散射效应，而所述横向声波S2的大部分声波能量主要通过声波反射作用返回所述谐振区10内并传播，有效地保证了所述横向声波S2的声波能量，因此在纵向声波反射器3和横向声波反射器4的配合作用下，横向声波谐振更少更弱，反谐振点的Q值大幅提高，从而获得较大的器件Q值。
进一步的，为了保证所述激发区101位于所述谐振区10内，所述纵向压电膜221沿所述第一方向向所述凸环2222的正投影落在所述凸环2222的内侧面2220所围成的范围内；所述凸环2222的内侧面2220所围成的区域沿所述第一方向向所述纵向声波反射器3的正投影完全落在所述纵向声波反射器3的范围内。
实施方式二
请参阅图4-5所示出了实施方式二的谐振器100a，图4实质为图2所示的结构的另一实施方式的示意图，实施方式二的谐振器100a是实施方式一的发声器件的衍生实施方式，两者的结构基本相同，对于相同部分不再一一赘述，而实施方式二的谐振器100a的主要的区别点在于：
纵向声波反射器3a为设置于基底1a靠近第一电极21a一侧的布拉格声反射镜，第一电极21a设置于该布拉格声反射镜远离基底1a一侧；更具体的，第一电极21a叠设于布拉格声反射镜远离基底1a的表面上，当然，在其他实施方式中，第一电极与布拉格声反射镜相互之间不直接叠设也是可行的，譬如，可以根据实际设计的需要，第一电极与布拉格声反射镜之间增加其它的膜层结构也是可行，。
进一步的，纵向声波反射器3a包括沿第一方向（即为谐振器100a的厚度方向，图中的X轴方向）叠设的第一膜层31a和第二膜层32a，第一膜层31a的声阻抗小于第二膜层32a的声阻抗，第一膜层31a与第二膜层32a共同形成布拉格声反射镜。
值得一提的是，第一膜层31a和第二膜层32a均分别包括至少两个，而上述两者的具体数量设置的可以根据实际使用的需要进行具体的设置，比如，在本实施方式中，第一膜层31a包括两个，第二膜层32a包括两个，第一膜层31a和第二膜层32a沿第一方向依次交替叠设。
与相关技术相比，本发明的谐振器中，纵向非压电膜包括环绕纵向压电膜且设置于第一电极远离基底一侧的主体部以及由主体部远离第一电极一侧向第二电极凸出延伸的呈环状的凸环，第二电极设置于主体部并盖设纵向压电膜之上，凸环的内侧面抵接于第二电极；凸环的内侧面沿第一方向向主体部的正投影所围成的区域为谐振区，谐振器位于谐振区外的区域为非谐振区；第一电极和第二电极均完全覆盖谐振区，且第二电极位于非谐振区的部分设置于凸环远离主体部的一侧；复合膜位于谐振区的部分的声阻抗与复合膜位于非谐振区的部分的声阻抗相异，且第一电极、压电功能膜和第二电极位于谐振区内的部分的声阻抗均是大致不变的；上述结构中，通过凸环的设置，引起了复合膜设置该凸环的位置的声阻抗增加，从而使得该凸环作为横向声波反射器，在横向声波向外传播过程中，只在横向声波反射器处发生一次声波散射效应，且横向声波反射器对横向声波主要发生的是声波反射作用，因此在纵向、横向声波反射器的共同作用下，横向波谐振更少更弱，反谐振点的Q值大幅提高。
以上所述的仅是本发明的实施方式，在此应当指出，对于本领域的普通技术人员来说，在不脱离本发明创造构思的前提下，还可以做出改进，但这些均属于本发明的保护范围。

Claims (10)

  1. 一种谐振器，其包括基底、沿第一方向设置于所述基底上方的复合膜以及设置于所述复合膜靠近所述基底一侧的纵向声波反射器，其特征在于，所述复合膜包括沿所述第一方向依次设置的第一电极、压电功能膜以及第二电极，所述第一电极设置于所述基底和所述纵向声波反射器之上；
    所述压电功能膜包括纵向压电膜以及纵向非压电膜，所述纵向压电膜设置于所述第一电极远离所述基底一侧，所述纵向非压电膜包括环绕所述纵向压电膜且设置于所述第一电极远离所述基底一侧的主体部以及由所述主体部远离所述第一电极一侧向所述第二电极凸出延伸的呈环状的凸环；所述凸环的内侧面沿所述第一方向向所述主体部的正投影所围成的区域为谐振区，所述谐振器位于所述谐振区外的区域为非谐振区；所述第一电极和所述第二电极均完全覆盖所述谐振区，且所述第二电极位于所述非谐振区的部分设置于所述凸环远离所述主体部的一侧；所述纵向压电膜位于所述谐振区内；所述谐振器位于所述谐振区的部分的声阻抗与所述谐振器位于所述非谐振区的部分的声阻抗相异，且所述第一电极、所述压电功能膜和所述第二电极位于所述谐振区内的部分的声阻抗均是大致不变的。
  2. 根据权利要求1所述的谐振器，其特征在于，所述第二电极包括位于所述谐振区内的第一部分和位于所述非谐振区并套设于所述第一部分远离所述主体部一侧的第二部分，所述第一部分叠设于所述主体部并盖设于所述纵向压电膜之上，所述凸环环绕所述第一部分且所述凸环的内侧面抵接于所述第一部分；所述第二部分设置于所述凸环远离所述主体部的一侧。
  3. 根据权利要求2所述的谐振器，其特征在于，所述纵向压电膜沿所述第一方向向所述凸环的正投影完全落在所述凸环的内侧面所围成的区域内。
  4. 根据权利要求3所述的谐振器，其特征在于，所述复合膜沿所述第一方向落在所述纵向压电膜的外侧面所围成的区域内的部分形成激发区，所述激发区位于所述谐振区内。
  5. 根据权利要求1所述的谐振器，其特征在于，所述纵向压电膜具有沿所述第一方向的压电系数，所述纵向非压电膜沿所述第一方向的压电系数为零或小于所述纵向压电膜沿所述第一方向的压电系数。
  6. 根据权利要求1所述的谐振器，其特征在于，所述纵向声波反射器为由所述基底靠近所述第一电极一侧向远离所述第一电极的方向凹陷形成的空腔结构。
  7. 根据权利要求1所述的谐振器，其特征在于，所述纵向声波反射器为设置于所述基底靠近所述第一电极一侧的布拉格声反射镜，所述第一电极设置于所述布拉格声反射镜远离所述基底一侧。
  8. 根据权利要求7所述的谐振器，其特征在于，所述纵向声波反射器包括沿所述第一方向叠设的第一膜层和第二膜层，所述第一膜层的声阻抗小于所述第二膜层的声阻抗，所述第一膜层与所述第二膜层共同形成所述布拉格声反射镜。
  9. 根据权利要求8所述的谐振器，其特征在于，所述第一膜层包括至少两个，所述第二膜层包括至少两个，所述第一膜层和所述第二膜层沿所述第一方向依次交替叠设。
  10. 根据权利要求1-9任一项所述的谐振器，其特征在于，所述凸环的内侧面所围成的区域沿所述第一方向向所述纵向声波反射器的正投影落在所述纵向声波反射器的范围内。
PCT/CN2020/123433 2020-07-10 2020-10-23 谐振器 Ceased WO2022007246A1 (zh)

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