WO2023070457A1 - 体声波谐振器和滤波器 - Google Patents

体声波谐振器和滤波器 Download PDF

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Publication number
WO2023070457A1
WO2023070457A1 PCT/CN2021/127146 CN2021127146W WO2023070457A1 WO 2023070457 A1 WO2023070457 A1 WO 2023070457A1 CN 2021127146 W CN2021127146 W CN 2021127146W WO 2023070457 A1 WO2023070457 A1 WO 2023070457A1
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Prior art keywords
acoustic wave
interdigital
electrodes
interdigital electrodes
piezoelectric layer
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PCT/CN2021/127146
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English (en)
French (fr)
Inventor
鲍景富
吴兆辉
龚柯源
梁起
李亚伟
黄裕霖
李昕熠
高宗智
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华为技术有限公司
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Priority to PCT/CN2021/127146 priority Critical patent/WO2023070457A1/zh
Publication of WO2023070457A1 publication Critical patent/WO2023070457A1/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
    • H03H9/02—Details
    • 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
    • H03H9/58—Multiple crystal filters

Definitions

  • the present disclosure relates generally to the field of resonators, and more particularly to bulk acoustic wave resonators.
  • the communication system usually works in the radio frequency (Radio Frequency) range, for example, for 5G communication technology, it communicates with a specific broadband of 3.3-4.9GHz.
  • Bulk acoustic resonators (bulk acoustic resonators, BARs) are widely used in communication systems to generate and select to send or receive specified frequency signals within a certain frequency bandwidth, and to reject frequency signals outside the frequency bandwidth.
  • BAR refers to a device that uses metal electrodes and piezoelectric materials in the form of a film to generate bulk acoustic waves, and achieves electrical frequency selection through acoustic resonance. BAR realizes the conversion of electrical energy to mechanical energy, converts electrical signals into sound waves, and then converts mechanical energy into electrical energy for output.
  • the energy loss of a resonator directly determines its quality factor.
  • the present disclosure relates to providing a bulk acoustic wave resonator and filter for reducing losses.
  • a bulk acoustic wave resonator is provided.
  • the interdigital transducer includes an input and output terminal, a bus bar (busbar ), and a plurality of interdigitated electrodes, the input and output terminals include input terminals and output terminals, the bus bars include input bus bars and output bus bars, and the plurality of interdigital electrodes include a plurality of first interdigital electrodes and a plurality of second interdigitated electrodes, the input end is connected to the input bus bar, the input bus bar is connected to the plurality of first interdigital electrodes, the output end is connected to the output bus bar, and
  • the output bus bar is connected to the plurality of second interdigital electrodes, and each second interdigital electrode of the plurality of second interdigital electrodes is connected to each first interdigital
  • the interdigital electrodes are coupled with each other one by one to form a plurality of interdigital electrode coupling pairs; wherein the bulk acoustic wave resonator also includes a plurality of acoustic wave suppression structures arranged periodically, and the acoustic wave suppression structures are arranged on adjacent interdigital electrodes between electrode coupling pairs.
  • the acoustic wave energy can be confined on the main mode, and the acoustic wave energy in the piezoelectric layer can be suppressed.
  • the spurious mode of the resonator improves the coupling coefficient of the resonator and reduces the loss.
  • At least one of the plurality of acoustic dampening structures includes an air void, wherein the air void includes through the piezoelectric layer.
  • the sound wave suppressing structure of the embodiment of the present disclosure can be conveniently formed by means of air voids.
  • At least one of the plurality of acoustic wave suppression structures includes a first phononic crystal array, wherein the first phononic crystal array includes a plurality of phononic crystal units, and the plurality of phononic crystal units Including a pattern of holes formed in the piezoelectric layer.
  • At least one of the plurality of acoustic wave suppression structures includes a second phononic crystal array, wherein the second phononic crystal array includes a plurality of phononic crystal units, and the plurality of phononic crystal units On the piezoelectric layer, the acoustic resistance of the plurality of phononic crystal unit materials is different from the acoustic resistance of the piezoelectric layer material. As a result, the structural performance of the resonator can be improved while ensuring the resonance performance of the resonator.
  • At least one acoustic wave suppressing structure of the plurality of acoustic wave suppressing structures is disposed in a region between adjacent interdigital electrodes. Thereby, stray modes in the region between adjacent interdigital electrodes of adjacent interdigital electrode coupling pairs in the bulk acoustic wave resonator can be suppressed.
  • the at least one acoustic wave suppression structure is arranged parallel to the extending direction of the interdigital electrodes.
  • At least one acoustic wave suppressing structure of the plurality of acoustic wave suppressing structures is disposed in a region between the interdigital electrode ends of adjacent interdigital electrode coupling pairs and the bus bar.
  • the at least one sound wave suppression structure is arranged parallel to the extending direction of the bus bar.
  • stray transverse modes TM, Transverse Modes
  • propagating between the interdigital electrode ends and the bus bars in the bulk acoustic wave resonator can be suppressed.
  • the interdigital electrodes of the first interdigital electrode coupling pair and the interdigital electrodes of the second interdigital electrode coupling pair arranged adjacently are mirror-symmetrically arranged with respect to the extending direction of the interdigital electrodes.
  • the coupling efficiency between the interdigital electrodes of the bulk acoustic wave resonator can be further improved through the electrodes arranged in pairs.
  • the bulk acoustic wave resonator is a bulk acoustic wave resonator (Freestanding BAR, FBAR).
  • the bulk acoustic wave resonator may further include a substrate and a substrate thin film disposed between the substrate and the piezoelectric layer, wherein the substrate is formed such that a region where the input terminal and the output terminal are located Arranged in a vacant position.
  • a bulk acoustic wave resonator in a suspension arrangement can be provided.
  • the bulk acoustic wave resonator is a solid mounted bulk acoustic wave resonator (Solid Mounted BAR, SM BAR).
  • the bulk acoustic wave resonator may further include a substrate and at least one Bragg reflection laminated body disposed between the lower surface of the piezoelectric layer and the substrate, the laminated body including a first layer made of materials having different acoustic impedances.
  • a low acoustic impedance membrane and a second high acoustic impedance membrane may be used to generate a first layer of materials having different acoustic impedances.
  • a resonator including the resonator described in any one of the above first aspects.
  • Fig. 1 shows a schematic perspective view of an example FBAR according to a first embodiment of the present disclosure.
  • FIG. 2 shows a schematic top view of an example FBAR according to the first embodiment of the present disclosure.
  • FIG. 3 shows a partially enlarged schematic diagram of an example FBAR device according to the first embodiment of the present disclosure.
  • Fig. 4 shows a cross-sectional view of the embodiment shown in Fig. 3 along line A-A'.
  • Fig. 5 shows a cross-sectional view of the embodiment shown in Fig. 3 along line B-B'.
  • Fig. 6 shows a cross-sectional view of the embodiment shown in Fig. 3 along line C-C'.
  • Fig. 7 shows a cross-sectional view of the embodiment shown in Fig. 3 along line D-D'.
  • Fig. 8 shows a cross-sectional view of the embodiment shown in Fig. 3 along the line EE'.
  • FIG. 9 shows a schematic perspective view of an FBAR according to an example of the second embodiment of the present disclosure.
  • FIG. 10 shows a schematic top view of an example FBAR according to the second embodiment of the present disclosure.
  • Fig. 11 shows a schematic diagram of a phononic crystal unit in a phononic crystal array according to an embodiment of the present disclosure.
  • Fig. 12 shows a schematic diagram of different implementations of a phononic crystal unit according to an embodiment of the present disclosure.
  • FIG. 13 shows a schematic perspective view of an example SM BAR according to a third embodiment of the present disclosure.
  • FIG. 14 shows a schematic top view of an exemplary SM BAR according to a third embodiment of the present disclosure.
  • FIG. 15 shows a partially enlarged schematic diagram of an example SM BAR according to three embodiments of the present disclosure.
  • Fig. 16 shows a cross-sectional view of the embodiment shown in Fig. 15 along line A-A'.
  • Fig. 17 shows a cross-sectional view of the embodiment shown in Fig. 15 along line B-B'.
  • Figure 18 shows a cross-sectional view of the embodiment shown in Figure 15 along line C-C'.
  • Fig. 19 shows a cross-sectional view of the embodiment shown in Fig. 15 along line D-D'.
  • Figure 20 shows a cross-sectional view of the embodiment shown in Figure 15 along the line EE'.
  • FIG. 21 shows a schematic perspective view of an example SM BAR according to a fourth embodiment of the present disclosure.
  • FIG. 22 shows a schematic top view of an exemplary SM BAR according to a fourth embodiment of the present disclosure.
  • 23-29 show schematic diagrams of methods for fabricating FBARs according to embodiments of the present disclosure.
  • the term “comprise” and its variants mean open inclusion, ie “including but not limited to”.
  • the term “or” means “and/or” unless otherwise stated.
  • the term “based on” means “based at least in part on”.
  • the terms “one example embodiment” and “one embodiment” mean “at least one example embodiment.”
  • the term “another embodiment” means “at least one further embodiment”.
  • a BAR is adapted to operate at a predetermined frequency to convert an electrical signal into an acoustic signal, and then convert the acoustic signal into an electrical signal.
  • the frequency range may be in the range of 3.3-4.9 GHz.
  • the inventors found that although the BAR suppresses most of the energy loss, there is still a small amount of energy leaking through the piezoelectric plane, causing a certain loss, which will affect the operation performance of the BAR.
  • the BAR when the BAR is used as a filter, there are some spurious waves in the filter, which affect the performance of the filter. It is expected that the loss of the BAR can be further reduced and the spurious waves of the BAR can be suppressed.
  • FIGS. 1-8 are schematic structural diagrams of an FBAR 100 according to an embodiment of the present disclosure.
  • the FBAR 100 is implemented as a suspended BAR.
  • the FBAR 100 includes: a piezoelectric layer 110 and an interdigital transducer (IDT) disposed on the piezoelectric layer 110.
  • IDT interdigital transducer
  • the interdigital transducer includes input and output terminals, a bus bar, and a plurality of interdigital electrodes.
  • the input and output terminals include an input terminal 120 and an output terminal 130 .
  • the input terminal 120 and the output terminal 130 are disposed on the upper surface of the piezoelectric layer 110 opposite to each other.
  • FBAR 100 also includes substrate film 140 and substrate 150.
  • the substrate film 140 and the substrate 150 are arranged to support the piezoelectric layer 110 .
  • the regions of the piezoelectric layer 110 in which the input 120 and the output 130 are situated are arranged floating.
  • the input end 120 can convert electrical energy into sound waves based on the inverse piezoelectric effect to form resonance, and the output end 130 can convert the generated sound wave signals into electrical signals based on the positive piezoelectric effect for output.
  • the input terminal 120 and the output terminal 130 are arranged at the center of the upper surface of the piezoelectric layer 110 .
  • the input terminal 120 includes an input bus bar 122 and a plurality of first interdigitated electrodes 124, 124' protruding from the input bus bar 122.
  • the plurality of first interdigitated electrodes 124, 124' are configured to convert a first electrical signal from the input bus bar 120 into an acoustic signal.
  • the output terminal 130 includes an output bus bar 132 and a plurality of second interdigitated electrodes 134, 134' protruding from the output bus bar 132 toward the input bus bar 122.
  • Each of the plurality of second interdigital electrodes 134, 134' is coupled with each of the plurality of first interdigital electrodes 124, 124' in a one-to-one correspondence to form a plurality of The pair of interdigitated electrodes is coupled to convert the acoustic signal into a second electrical signal.
  • the second interdigital electrode 134 is physically coupled to the first interdigital electrode 124 to form an interdigital electrode pair;
  • the second interdigital electrode 134' is physically coupled to the first interdigital electrode 124' coupled to ground to form an interdigitated electrode pair.
  • the plurality of interdigital electrode coupling pairs includes a first interdigital electrode coupling pair and a second interdigital electrode coupling pair arranged adjacently.
  • the FBAR 100 may also include a ground electrode 170 placed around the edge of the piezoelectric layer 110 so as to surround the input terminal 120 and the output terminal 130.
  • the input end 120 and the output end 130 can be made of metal conductor material.
  • the metallic conductor material may include gold, aluminum, copper, silver, molybdenum, tungsten, and the like.
  • the piezoelectric layer 110 may be made of a material with good piezoelectric performance.
  • the material of the piezoelectric layer 110 may include lithium niobate, lithium niobate, or aluminum nitride, thereby achieving a high coupling coefficient.
  • the material of the substrate 150 is an insulating material, which is suitable for providing good stability.
  • the material of the substrate 150 may include high resistance silicon, silicon carbide, sapphire, diamond, quartz, and the like.
  • the substrate film 140 as a transition layer between the piezoelectric layer 110 and the substrate 150 may be made of a low acoustic impedance material.
  • the material of the substrate film 140 may include silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), silicon (Si), aluminum (Al), zinc oxide (ZnO), and the like.
  • the BAW resonator further includes a plurality of acoustic wave suppression structures 160 arranged periodically, and each acoustic wave suppression structure 160 is arranged between the adjacent first coupling pair of interdigital electrodes and the second coupling pair of interdigital electrodes.
  • the stray sound waves near the interdigital electrodes can be effectively suppressed by a plurality of acoustic wave suppression structures 160 arranged between adjacent first interdigital electrode coupling pairs and second interdigital electrode coupling pairs. Therefore, FBAR can confine the acoustic wave energy to the main mode, improve the coupling coefficient of the resonator and reduce the loss.
  • an acoustic wave suppressing structure is arranged between each interdigital electrode pair among the plurality of adjacent interdigital electrode pairs. In some embodiments, an acoustic wave suppressing structure is arranged between some interdigital electrode pairs among the plurality of adjacent interdigital electrode pairs.
  • Acoustic dampening structure 160 may include a variety of implementations.
  • the acoustic dampening structure 160 may be implemented in the form of air voids.
  • the acoustic wave suppression structure 160 is implemented as an air hole; the air hole penetrates through the piezoelectric layer.
  • the acoustic wave suppression structure 160 may be implemented in the form of a phononic crystal array (described in detail later with reference to FIGS. 9-12 ).
  • the acoustic dampening structure 160 may also be implemented in the form of a combination of air voids and phononic crystal arrays.
  • the acoustic wave suppression structure 160 is realized as a rectangular air hole. It should be understood that this is only exemplary, and the sound wave suppressing structure 160 may be implemented in any other suitable shape, such as other polygons, circles, ellipses, or other regular or irregular patterns capable of realizing the functions of the present disclosure. These shapes are all within the scope of the acoustic wave suppressing structure 160 according to the embodiments of the present disclosure.
  • the acoustic wave suppression structure 160 may be disposed on the first acoustic wave suppression structure 162, 162', the first acoustic wave suppression structure 162, 162', 166.
  • area between interdigital electrodes herein refers to an area where corresponding interdigital electrodes of adjacent interdigital electrode coupled pairs extend adjacent to each other. The stray modes distributed in the extending direction of the interdigital electrodes in the piezoelectric layer 110 can be effectively suppressed by the first acoustic wave suppressing structures 162, 162', 166.
  • the first acoustic dampening structure 162, 162', 166 is disposed parallel to the interdigital electrodes 124, 124', 134, 134'.
  • the stray longitudinal modes distributed in the longitudinal direction in the piezoelectric layer 110 can be effectively suppressed by the first acoustic wave suppressing structures 162, 162', 166 arranged in parallel.
  • the acoustic dampening structure 160 may be disposed in the area between the interdigital electrode ends and the bus bars.
  • the acoustic dampening structure 160 may include a second acoustic dampening structure 164, 164' positioned between the ends of the first interdigitated electrodes 124, 124' and the output bus bar 132. Therefore, the stray modes distributed near the ends of the first interdigital electrodes 124, 124' and the output bus bar 132 in the piezoelectric layer 110 can be effectively suppressed by the second acoustic wave suppression structures 164, 164'.
  • the second acoustic dampening structure 164, 164&apos is parallel to the output bus bar 132. Thereby, stray lateral modes distributed in the lateral direction in the piezoelectric layer 110 can be effectively suppressed.
  • the acoustic dampening structure 160 may include a third acoustic dampening structure 168 positioned between the ends of the second interdigitated electrodes 134, 134' and the input bus bar 122, as shown. Therefore, the stray modes distributed near the ends of the second interdigital electrodes 134, 134' and the input bus bar 122 in the piezoelectric layer 110 can be effectively suppressed by the third acoustic wave suppression structure 168.
  • the third acoustic wave suppression structure 168 is parallel to the input bus bar 122 . Thereby, stray lateral modes distributed in the lateral direction in the piezoelectric layer 110 can be effectively suppressed.
  • the interdigital electrodes of the first interdigital electrode coupling pair and the interdigital electrodes of the second interdigital electrode coupling pair arranged adjacently are relative to the extension direction of the interdigital electrodes Arranged mirror-symmetrically.
  • the first interdigital electrodes 124, 124' of the input terminal 120 may include multiple pairs of first interdigital electrodes arranged in pairs.
  • Each pair of first interdigital electrodes may include a first first interdigital electrode 124 and a second first interdigital electrode 124'.
  • the second interdigital electrodes 134, 134' of the output terminal 130 may include a plurality of pairs of second interdigital electrodes arranged in pairs.
  • Each pair of second interdigital electrodes may include a first second interdigital electrode 134 and a second second interdigital electrode 134'.
  • Each pair of second interdigital electrodes is coupled with each pair of second interdigital electrodes in a one-to-one correspondence.
  • each set of first interdigital electrodes is arranged in pairs, this is only exemplary. In other unshown embodiments, each group of first interdigital electrodes may include two pairs of interdigital electrodes or more than two interdigital electrodes.
  • each pair of first interdigitated electrodes at the input terminal 120 and each pair of second interdigitated electrodes at the output terminal 130 follow the first first interdigital electrode 124, first second interdigital electrode
  • the electrode 134 , the second and second interdigital electrodes 134 ′, and the second and first interdigital electrodes 124 ′ are arranged on the piezoelectric layer 110 in sequence.
  • the interdigitated structure arranged according to such mirror symmetry can effectively utilize the structural symmetry of the first interdigitated electrode of the input terminal 120 and the symmetry of the second interdigitated electrode of the output terminal 130, thereby further enhancing the piezoelectric layer 110. Suppression performance of spurious modes in .
  • the interdigital electrodes of the first interdigital electrode coupling pair and the interdigital electrodes of the second interdigital electrode coupling pair disposed adjacent to each other are extended relative to the interdigital electrodes
  • the directions may not be arranged mirror-symmetrically.
  • each pair of first interdigital electrodes at the input end 120 and each pair of second interdigital electrodes at the output end 130 follow the first first interdigital electrode 124, the first The second interdigital electrode 134 , the second first interdigital electrode 124 ′, and the second second interdigital electrode 134 ′ are arranged on the piezoelectric layer 110 in sequence.
  • the acoustic wave suppression structure 162 on the outside of the first interdigitated electrode 124 may be arranged symmetrically with respect to the direction of propagation of the acoustic wave of the FBAR.
  • the stray modes in the piezoelectric film 110 can be further suppressed by the symmetrical arrangement of the acoustic wave suppressing structures 162, 162'.
  • the acoustic dampening structures 164, 164&apos may be arranged symmetrically about the direction of acoustic propagation of the FBAR.
  • the stray modes in the piezoelectric film 110 can be further suppressed by the symmetrically arranged acoustic wave suppression structures 164, 164'.
  • the air gaps of the sound wave suppression structure 160 described in FIGS. 1-8 are replaced by soft materials.
  • Soft materials include filling materials with relatively low density and small elastic coefficient, such as silicon dioxide, etc. for filling. Similar properties can also be achieved by including soft fillings, for example.
  • FIGS. 9-10 show schematic perspective views of an FBAR 200 according to an example of a second embodiment of the present disclosure.
  • the FBAR 200 shown in FIGS. 9 and 10 is similar to the FBAR 100 shown in FIGS. 1-8 , and the FBAR 200 is implemented as a suspended FBAR.
  • the structure of the FBAR 200 is similar to that of the FBAR 100, except that the acoustic wave suppression structure 260 of the FBAR 200 in the embodiment of Figures 9-10 is different from the acoustic wave suppression structure 160 of the FBAR 100 in the embodiment of Figures 1-8.
  • components similar to those of FIGS. 1-8 are coded with reference numerals having similar suffixes. For the convenience of simplification, focus on describing the difference between the structure of FBAR 200 and FBAR 100.
  • the FBAR 200 includes: a piezoelectric layer 210 , an input terminal 220 , an output terminal 230 , a substrate film 240 and a substrate 250 .
  • the input terminal 220 and the output terminal 230 are disposed on the upper surface of the piezoelectric layer 210 opposite to each other.
  • the substrate film 240 and the substrate 250 are arranged to support the piezoelectric layer 210 .
  • the input end 220 can convert electrical energy into sound waves based on the inverse piezoelectric effect to form resonance, and the output end 230 can convert the generated sound wave signals into electrical signals based on the positive piezoelectric effect for output.
  • the input terminal 220 includes an input bus bar 222 and a plurality of first interdigitated electrodes 224, 224' protruding from the input bus bar 222.
  • the output terminal 130 includes an output bus bar 232 and a plurality of second interdigitated electrodes 234, 234' protruding from the output bus bar 232 toward the input bus bar 222.
  • the second interdigital electrode 234 is physically coupled to the first interdigital electrode 224 to form an interdigital electrode pair;
  • the second interdigital electrode 234' is physically coupled to the first interdigital electrode 224'. coupled to ground to form an interdigitated electrode pair.
  • the ground electrode 270 is placed around the edge of the piezoelectric layer 210 so as to surround the input terminal 220 and the output terminal 230 .
  • the BAW resonator further includes a plurality of acoustic wave suppression structures 260 arranged periodically, and the acoustic wave suppression structures 260 are disposed between the first coupling pair of interdigital electrodes and the second coupling pair of interdigital electrodes. Stray acoustic waves in the vicinity of the interdigital electrodes can be effectively suppressed by the acoustic wave suppression structure 260 disposed adjacent to the corresponding interdigital electrodes. Therefore, FBAR 200 can confine the acoustic energy to the main mode, improve the coupling coefficient of the resonator and reduce the loss.
  • the acoustic dampening structure 260 is implemented in the form of a combination of air apertures 268, 264, 264' and phononic crystal arrays 262, 262', 266.
  • the acoustic wave suppression structure 260 may include a first acoustic wave suppression structure 260 between adjacent interdigital electrodes of the first interdigital electrode coupling pair and the second interdigital electrode coupling pair. Structures 262, 262', 266.
  • the stray modes distributed in the extending direction of the interdigital electrodes in the piezoelectric layer 210 can be effectively suppressed by the first acoustic wave suppressing structures 262, 262', 266.
  • the first acoustic dampening structure 262, 262' is disposed parallel to the interdigital electrodes 224, 224', 234, 234'.
  • the stray longitudinal modes distributed in the longitudinal direction in the piezoelectric layer 210 can be effectively suppressed by the first acoustic wave suppressing structures 262, 262' arranged in parallel.
  • the acoustic dampening structure 260 may be disposed in the region between the interdigital electrode ends and the bus bars.
  • the acoustic dampening structure 260 may include a second acoustic dampening structure 264, 264' positioned between the ends of the first interdigitated electrodes 224, 224' and the output bus bar 232, as shown.
  • the stray modes distributed near the ends of the first interdigital electrodes 224, 224' and the output bus bar 232 in the piezoelectric layer 210 can be effectively suppressed by the second acoustic wave suppression structures 264, 264'.
  • the second acoustic dampening structure 264, 264&apos is parallel to the output bus bar 232. Thereby, stray lateral modes distributed in the lateral direction in the piezoelectric layer 210 can be effectively suppressed.
  • the acoustic dampening structure 260 may include a third acoustic dampening structure 268 positioned between the ends of the second interdigitated electrodes 234, 234' and the input bus bar 222, as shown. Therefore, the stray modes distributed near the ends of the second interdigital electrodes 234, 234' and the input bus bar 222 in the piezoelectric layer 210 can be effectively suppressed by the third acoustic wave suppression structure 268.
  • the third acoustic wave suppression structure 268 is parallel to the input bus bar 222 . Thereby, stray lateral modes distributed in the lateral direction in the piezoelectric layer 210 can be effectively suppressed.
  • the first interdigital electrodes 224, 224' of the input terminal 220 may include multiple pairs of first interdigital electrodes arranged in pairs.
  • Each pair of first interdigital electrodes may include a first first interdigital electrode 224 and a second first interdigital electrode 224'.
  • the second interdigital electrodes 234, 234' of the output terminal 230 may include a plurality of pairs of second interdigital electrodes arranged in pairs.
  • Each pair of second interdigital electrodes may include a first second interdigital electrode 234 and a second second interdigital electrode 234'.
  • each set of first interdigital electrodes is arranged in pairs, this is only exemplary. In other unshown embodiments, each group of first interdigital electrodes may include two pairs of interdigital electrodes or more than two interdigital electrodes.
  • each pair of first interdigitated electrodes at the input terminal 220 and each pair of second interdigitated electrodes at the output terminal 230 follow the first first interdigital electrode 224, first second interdigital electrode
  • the electrode 234 , the second and second interdigital electrodes 234 ′, and the second and first interdigital electrodes 224 ′ are arranged on the piezoelectric layer 210 in sequence.
  • the interdigital structure arranged according to such a mirror image symmetry can effectively utilize the structural symmetry of the first interdigital electrode at the input end 220 and the symmetry of the second interdigital electrode at the output end 230, thereby further enhancing the piezoelectric layer 210. Suppression performance of spurious modes in .
  • the acoustic wave suppression structure 260 may include a plurality of acoustic wave suppression structures arranged symmetrically.
  • the phononic crystal array may include a plurality of phononic crystal units 265, 265a, 265b arranged in various patterns.
  • Phononic crystal units can include a variety of implementations. Multiple phononic crystal units can achieve sound wave filtering while meeting the rigidity requirements of the sound wave suppression structure, thereby further improving the durability of the FBAR.
  • the acoustic dampening structures 262, 262', 266 are shown as arrays of phononic crystals; while the acoustic dampening structures 268, 264, 264' are shown as air gaps; This is exemplary only, and the acoustic dampening structure 260 may be provided in any arrangement of phononic crystal arrays, air gaps, or combinations thereof.
  • FIG. 11 shows an example of the phononic crystal unit 265 .
  • the phononic crystal unit 265 may be formed by forming a plurality of air gaps in the piezoelectric layer.
  • the air gap can have various shapes.
  • each phononic crystal unit 265 can be in the shape of a square with side length a1; the air gap is formed in the shape of a cross, the width of the short side of the cross can be 0.25a1, and the width of the long side Can be 0.95a1.
  • a1 can be selected or adjusted according to the bandwidth frequency to meet the required acoustic wave filtering performance.
  • the size of the air gap can also be selected or adjusted according to the bandwidth frequency to meet the required acoustic filtering performance.
  • the shape of the phononic crystal unit 265 is symmetrical with respect to the sound wave propagation direction to further enhance the filtering performance.
  • FIG. 12 shows other different embodiments of the phononic crystal unit 265 .
  • the phononic crystal unit 265 may be made of air as the acoustic wave boundary surface, or may be formed of a material other than acoustic resistance.
  • the phononic crystal array is a first phononic crystal array including a plurality of phononic crystal units including a pattern of holes formed in the piezoelectric layer.
  • the phononic crystal array is a second phononic array comprising a plurality of phononic crystal units, wherein the plurality of phononic crystal units are located on the piezoelectric layer, and the acoustic resistance of the material of the plurality of phononic crystal units is different from The acoustic resistance of the piezoelectric layer material.
  • the phononic crystal unit 265a may be formed on the upper surface of the piezoelectric layer and formed of a material having an acoustic resistance different from that of the piezoelectric layer.
  • the phononic crystal unit 265a may be realized in various shapes.
  • the phononic crystal unit 265a may include a combination of various shape patterns, as examples rectangles, squares, circles, rhombuses, ellipses, and the like.
  • phononic crystal unit 265a may include various combinations of irregular patterns or regular patterns.
  • the shape of the phononic crystal unit 265a is symmetrical with respect to the sound wave propagation direction, so as to further enhance the filtering performance.
  • the size of the phononic crystal unit 265a can be selected or adjusted according to the bandwidth frequency,
  • the phononic crystal unit 265b may be formed with air as the acoustic wave boundary surface.
  • the phononic crystal unit 265a may be formed by forming various air gaps in the piezoelectric layer.
  • the air gap can be of various shapes.
  • the phononic crystal unit 265b may include a combination of various shape patterns, as example shapes of circles, crosses, etc., or combinations thereof.
  • the size of the phononic crystal unit 265b can be selected or adjusted according to the bandwidth frequency.
  • the shape of the phononic crystal unit 265b is symmetrical with respect to the sound wave propagation direction to further enhance the filtering performance.
  • FIGS. 13-20 show schematic perspective views of an example SM BAR 300 according to a third embodiment of the present disclosure.
  • the SM BAR 300 shown in Figures 13 and 20 is similar to the SM BAR 100 shown in Figures 1-8. The difference is that the SM BAR300 is implemented as a Solid Mounted SM BAR.
  • components similar to those of FIGS. 1-8 are coded with reference numerals having similar suffixes. For the convenience of simplifying the description, focus on describing the difference between the structure of SM BAR 300 and SM BAR 100.
  • the SM BAR 300 is implemented as a solid-state attached SM BAR.
  • the SM BAR 300 includes: a piezoelectric layer 310, an input end 320, an output end 330, a Bragg reflection stack 380, and a substrate 350.
  • the input terminal 320 and the output terminal 330 are disposed on the upper surface of the piezoelectric layer 310 opposite to each other.
  • the input end 320 can convert electrical energy into sound waves based on the inverse piezoelectric effect to form resonance, and the output end 330 can convert the generated sound wave signals into electrical signals based on the positive piezoelectric effect for output.
  • the stack 380 includes a plurality of stacks of first low acoustic impedance films 382a, 382b and second high acoustic impedance films 384a, 384b made of materials having different acoustic impedances. In some embodiments, there may be at least two of these Bragg reflective stacks.
  • the main mode energy is confined in the piezoelectric layer with maximum efficiency by using a Bragg reflection laminate formed by alternately stacking materials with high acoustic impedance and low acoustic impedance.
  • High acoustic impedance materials can usually choose tungsten (W), aluminum nitride (AlN), ruthenium (Ru), etc.; low acoustic impedance film materials can usually choose silicon dioxide (SiO2), silicon nitride (Si3N4), silicon (Si ), aluminum (Al), zinc oxide (ZnO), etc.
  • the input terminal 320 and the output terminal 330 are arranged at the center of the upper surface of the piezoelectric layer 310 .
  • the input terminal 320 includes an input bus bar 322 and a plurality of first interdigitated electrodes 324, 324' protruding from the input bus bar 322.
  • the plurality of first interdigitated electrodes 324, 324' are configured to convert a first electrical signal from the input bus bar 320 into an acoustic signal.
  • the output terminal 330 includes an output bus bar 332 and a plurality of second interdigitated electrodes 334, 334' protruding from the output bus bar 332 toward the input bus bar 322.
  • the second interdigital electrode 334 is physically coupled to the first interdigital electrode 324 to form an interdigital electrode pair; the second interdigital electrode 334' is physically coupled to the first interdigital electrode 324' to form an interdigital electrode right.
  • Each of the plurality of second interdigital electrodes 334, 334' is coupled with each of the plurality of first interdigital electrodes 324, 324' in a one-to-one correspondence to form a plurality of Interdigitated electrode coupled pairs.
  • the SM BAR 300 may also include a ground electrode 370 placed around the edge of the piezoelectric layer 310 so as to surround the input 320 and the output 330.
  • the bulk acoustic wave resonator further includes a plurality of acoustic wave suppression structures 360 arranged periodically, and the acoustic wave suppression structures 360 are arranged between the first coupling pair of interdigital electrodes and the second coupling pair of interdigital electrodes. Stray acoustic waves in the vicinity of the interdigital electrodes can be effectively suppressed by the acoustic wave suppression structure 360 disposed adjacent to the corresponding interdigital electrodes.
  • SM BAR 300 can confine the acoustic energy to the main mode, improve the coupling coefficient of the resonator and reduce the loss.
  • Acoustic suppression structure 360 may include a variety of implementations.
  • the acoustic dampening structure 360 may be implemented in the form of air voids, for example, wherein the air voids may be disposed through the piezoelectric layer.
  • the acoustic dampening structure 360 is implemented as an air aperture.
  • the acoustic wave suppression structure 360 may be implemented in the form of a phononic crystal array (described in detail later with reference to FIGS. 21-22 ).
  • the acoustic wave suppression structure 360 may include a region disposed between adjacent interdigital electrodes of the first interdigital electrode coupling pair and the second interdigital electrode coupling pair.
  • the first acoustic dampening structure 362, 362', 366 is disposed parallel to the interdigital electrodes 324, 324', 334, 334'.
  • the stray longitudinal modes distributed in the longitudinal direction in the piezoelectric layer 310 can be effectively suppressed by the first acoustic wave suppressing structures 362, 362', 366 arranged in parallel.
  • the acoustic dampening structure 360 may include a second acoustic dampening structure 364, 364' positioned between the ends of the first interdigitated electrodes 324, 324' and the output bus bar 332, as shown. Therefore, the stray modes distributed near the ends of the first interdigital electrodes 324, 324' and the output bus bar 332 in the piezoelectric layer 310 can be effectively suppressed by the second acoustic wave suppression structures 364, 364'.
  • the second acoustic dampening structure 364, 364&apos is parallel to the output bus bar 332. Thereby, stray lateral modes distributed in the lateral direction in the piezoelectric layer 310 can be effectively suppressed.
  • the acoustic dampening structure 360 may include a third acoustic dampening structure 368 positioned between the ends of the second interdigitated electrodes 334, 334' and the input bus bar 322, as shown. Therefore, the stray modes distributed near the ends of the second interdigital electrodes 334, 334' and the input bus bar 322 in the piezoelectric layer 310 can be effectively suppressed by the third acoustic wave suppression structure 368.
  • the third acoustic dampening structure 368 is parallel to the input bus bar 322 . Thereby, stray lateral modes distributed in the lateral direction in the piezoelectric layer 310 can be effectively suppressed.
  • the first interdigital electrodes 324, 324' of the input terminal 320 may include multiple pairs of first interdigital electrodes arranged in pairs.
  • Each pair of first interdigital electrodes may include a first first interdigital electrode 324 and a second first interdigital electrode 324'.
  • the second interdigital electrodes 334, 334' of the output terminal 330 may include a plurality of pairs of second interdigital electrodes arranged in pairs.
  • Each pair of second interdigital electrodes may include a first second interdigital electrode 334 and a second second interdigital electrode 334'.
  • each set of first interdigital electrodes is arranged in pairs, this is only exemplary. In other unshown embodiments, each group of first interdigital electrodes may include two pairs of interdigital electrodes or more than two interdigital electrodes.
  • each pair of first interdigitated electrodes at the input terminal 320 and each pair of second interdigitated electrodes at the output terminal 330 follow the first first interdigital electrode 324, first second interdigital electrode
  • the electrode 334 , the second and second interdigital electrodes 334 ′, and the second and first interdigital electrodes 324 ′ are arranged on the piezoelectric layer 310 in sequence.
  • the interdigital electrode structure arranged according to the mirror image symmetry can effectively utilize the structural symmetry of the first interdigital electrode at the input end 320 and the symmetry of the second interdigital electrode at the output end 330, thereby further enhancing the piezoelectric layer 310. Suppression performance of spurious modes.
  • the acoustic wave suppression structure 360 may include a plurality of acoustic wave suppression structures arranged symmetrically.
  • the acoustic dampening structures 362, 362' may be arranged symmetrically about the direction of acoustic propagation of the SM BAR.
  • the stray modes in the piezoelectric layer 310 can be further suppressed by the symmetrically arranged acoustic wave suppressing structures 362, 362'.
  • the acoustic dampening structures 364, 364' may be arranged symmetrically about the direction of acoustic propagation of the SM BAR.
  • the stray modes in the piezoelectric layer 310 can be further suppressed by the symmetrically arranged acoustic wave suppression structures 364, 364'.
  • the air gaps of the acoustic wave suppression structure 360 described in FIGS. 13-20 are replaced by soft materials.
  • Soft materials include filling materials with relatively low density and small elastic coefficient, such as silicon dioxide, etc. for filling. Similar properties can also be achieved by including soft fillings, for example.
  • FIGS. 21-22 show schematic perspective views of an example SM BAR 400 according to a fourth embodiment of the present disclosure.
  • the SM BAR 400 shown in Fig. 21-Fig. 22 is similar to the SM BAR 300 shown in Fig. 13-Fig.
  • components similar to those of FIGS. 13-20 are numbered with reference numerals having similar suffixes.
  • the SM BAR 400 includes: a piezoelectric layer 410 , an input end 420 , an output end 430 , a Bragg reflection stack 480 and a substrate 450 .
  • the stack 480 includes a plurality of stacks of first low acoustic impedance films 482a, 482b and second high acoustic impedance films 484a, 484b made of materials having different acoustic impedances.
  • the main mode energy is confined in the piezoelectric layer with maximum efficiency by using a Bragg reflection laminate formed by alternately stacking materials with high acoustic impedance and low acoustic impedance.
  • the input terminal 420 includes an input bus bar 422 and a plurality of first interdigitated electrodes 424, 424' protruding from the input bus bar 422.
  • the output terminal 130 includes an output bus bar 432 and a plurality of second interdigitated electrodes 434, 434' protruding from the output bus bar 432 toward the input bus bar 422.
  • the second interdigital electrode 434 is physically coupled to the first interdigital electrode 424 to form an interdigital electrode pair; the second interdigital electrode 434' is physically coupled to the first interdigital electrode 424' to form an interdigital electrode right.
  • Each of the plurality of second interdigital electrodes 434, 434' is coupled with each of the plurality of first interdigital electrodes 424, 424' in a one-to-one correspondence to form a plurality of Interdigitated electrode coupled pairs.
  • the ground electrode 470 is placed around the edge of the piezoelectric layer 410 so as to surround the input terminal 420 and the output terminal 430 .
  • the bulk acoustic wave resonator further includes a plurality of acoustic wave suppression structures 460 arranged periodically, and the acoustic wave suppression structures 460 are arranged between the first coupling pair of interdigital electrodes and the second coupling pair of interdigital electrodes. Stray acoustic waves in the vicinity of the interdigital electrodes can be effectively suppressed by the acoustic wave suppression structure 460 disposed adjacent to the corresponding interdigital electrodes.
  • SM BAR 400 can confine the acoustic wave energy to the main mode, improve the coupling coefficient of the resonator and reduce the loss.
  • the acoustic dampening structure 460 is implemented in the form of a combination of air apertures 468, 464, 464' and phononic crystal arrays 462, 462', 466. It is worth noting that this is only exemplary, and the sound wave suppression structure 460 may also be implemented in the form of a phononic crystal array.
  • the phononic crystal array may include a plurality of phononic crystal units arranged in various patterns. Phononic crystal units can include a variety of implementations. Through multiple phononic crystal units, sound wave filtering can be achieved while meeting the rigidity requirements of the sound wave suppression structure, thereby further improving the durability of the SM BAR.
  • the phononic crystal array may be similar to the phononic crystal array provided in FIG. 10 , and its detailed description is omitted.
  • the acoustic suppression structures 462, 462', 466 are shown as arrays of phononic crystals; while the acoustic suppression structures 468, 464, 464' are shown as air gaps; This is exemplary only, and the acoustic dampening structure 460 may be provided in any arrangement of phononic crystal arrays, air gaps, or combinations thereof.
  • An embodiment of the present application provides a filter, which includes the resonator described in any one of the above aspects.
  • These filters can be provided in electronic equipment for processing on signals.
  • an electronic device is provided with a printed circuit board (printed circuit board, PCB) and an electronic device connected to the printed circuit board; wherein, the electronic device is provided with a resonator; the application for the electronic device
  • the electronic device may be a product or component capable of generating a resonance frequency such as a filter, a sensor, or a transformer.
  • the electronic equipment can be electronic products such as televisions, mobile phones, televisions, tablet computers, notebooks, vehicle-mounted computers, smart watches, smart bracelets, and satellite communication equipment.
  • the resonator may be a surface acoustic wave (surface acoustic wave, SAW) resonator, a Lamb wave (lamb) resonator, a microelectromechanical system ( micro-electro-mechanical system, MEMS) resonators, etc.
  • SAW surface acoustic wave
  • Lamb wave Lamb wave
  • MEMS microelectro-mechanical system
  • a substrate film 140 is deposited on a substrate 150 by plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD).
  • PECVD plasma enhanced chemical vapor deposition
  • CMP chemical mechanical polishing
  • the piezoelectric wafer is treated by He+ ion implantation method and the surface of the piezoelectric wafer is treated, and the treated piezoelectric wafer is bonded to the substrate film 140 .
  • etching is performed on the substrate 150 from the backside to form a suspended structure; then, a protective film 180 is deposited, for example, by PECVD, as shown in FIG. 26 .
  • the pattern of the air pores 160 is defined, and the protective film 180 is etched to form the air pores 160, as shown in FIG. 28 .
  • the top protection film 180 is released to finally form the bulk acoustic wave resonator 100 .

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Abstract

本公开的实施例提供了一种体声波谐振器和滤波器。体声波谐振器包括：压电层；以及叉指换能器(IDT)，所述叉指换能器设置于所述压电层上；多个第二叉指电极中的每个第二叉指电极与多个第一叉指电极中的每个第一叉指电极一一对应地相互耦合构成多个叉指电极耦合对；其中体声波谐振器还包括周期性排列的多个声波抑制结构，所述多个声波抑制结构中的每个声波抑制结构被设置于相邻叉指电极耦合对之间。由此，可以在宽频率范围内抑制带内杂散模式，降低损耗。

Description

体声波谐振器和滤波器 技术领域
本公开总体上涉及谐振器领域，更具体地涉及体声波谐振器。
背景技术
通信***通常在射频(Radio Frequency)范围内工作，例如针对5G通信技术，以3.3-4.9GHz的特定宽带通信。体声波谐振器(bulk acoustic resonator，BAR)被广泛地用于通信***，以用于生成并选择发送或接收某一频带宽度内的指定的频率信号，并拒绝频带宽度之外的频率信号。BAR是指利用膜形态的金属电极和压电材料产生体声波，并通过声学谐振实现电学选频的器件。BAR实现了电能到机械能的转化，使电信号转化为声波的形式，然后再将机械能转换成电能进行输出。
谐振器的能量损耗直接决定了其品质因数，谐振器的能量损耗越小，其品质因数越高，谐振器的性能也就越好，因此，提高谐振器的品质因数成为目前改善谐振器性能的主要途径之一。
发明内容
本公开涉及提供了一种体声波谐振器和滤波器，用于降低损耗。
在本公开的第一方面，提供了一种体声波谐振器。体声波谐振器压电层；以及叉指换能器(IDT)，所述叉指换能器设置于所述压电层上；所述叉指换能器包括输入输出端、汇流条(busbar)、以及多个叉指电极，所述输入输出端包括输入端和输出端，所述汇流条包括输入汇流条和输出汇流条，所述多个叉指电极包括多个第一叉指电极和多个第二叉指电极，所述输入端与所述输入汇流条连接，所述输入汇流条与所述多个第一叉指电极连接，所述输出端与所述输出汇流条连接，所述输出汇流条与所述多个第二叉指电极连接，所述多个第二叉指电极中的每个第二叉指电极与所述多个第一叉指电极中的每个第一叉指电极一一对应地相互耦合构成多个叉指电极耦合对；其中所述体声波谐振器还包括周期性排列的多个声波抑制结构，所述声波抑制结构被设置于相邻的叉指电极耦合对之间。
根据本公开实施例的体声波谐振器，通过设置于相邻的叉指电极耦合对之间的周期性排列的多个声波抑制结构，能够将声波能量约束在主模上，抑制压电层内的杂散模式(spurious mode)，提高谐振器的耦合系数和降低损耗。
在一些实施例中，所述多个声波抑制结构中的至少一个包括空气孔隙，其中所述空气孔隙包括贯通所述压电层。根据本公开实施例的声波抑制结构，可以借助空气孔隙方便地形成声波抑制结构。
在一些实施例中，所述多个声波抑制结构中的至少一个包括第一声子晶体阵列，其中所述第一声子晶体阵列包括多个声子晶体单元，所述多个声子晶体单元包括形成在压电层中的孔图案。由此，可以确保谐振器的谐振性能的同时，提高谐振器的结构性能。
在一些实施例中，所述多个声波抑制结构中的至少一个包括第二声子晶体阵列，其中所述第二声子晶体阵列包括多个声子晶体单元，所述多个声子晶体单元位于所述压电层上，所述多个声子晶体单元材料的声阻不同于所述压电层材料的声阻。由此，可以确 保谐振器的谐振性能的同时，提高谐振器的结构性能。
在一些实施例中，所述多个声波抑制结构中的至少一个声波抑制结构被设置于相邻叉指电极之间的区域。由此，可抑制体声波谐振器中在相邻叉指电极耦合对的相邻叉指电极之间区域中的杂散模式。
在一些实施例中，所述至少一个声波抑制结构与所述叉指电极的延伸方向平行地设置。由此，可抑制体声波谐振器中在叉指电极的延伸方向上传播的杂散纵向模式(LM，Longitudinal Modes)。
在一些实施例中，所述多个声波抑制结构中的至少一个声波抑制结构被设置于相邻叉指电极耦合对的叉指电极末端与所述汇流条之间的区域。由此，可抑制体声波谐振器中叉指电极末端与汇流条之间传播的杂散模式。
在一些实施例中，所述至少一个声波抑制结构与所述汇流条的延伸方向平行地设置。由此，可抑制体声波谐振器中叉指电极末端与汇流条之间传播的杂散横向模式(TM,Transverse Modes)。
在一些实施例中，相邻设置的第一叉指电极耦合对的叉指电极和第二叉指电极耦合对的叉指电极相对于叉指电极的延伸方向镜像对称地布置。由此，通过成对布置的电极，可以进一步提高体声波谐振器的叉指电极之间的耦合效率。
在一些实施例中，体声波谐振器为体声波谐振器(Freestanding BAR，FBAR)。体声波谐振器还可包括衬底和布置在所述衬底和所述压电层之间的衬底薄膜，其中所述衬底被形成为使得所述输入端和所述输出端所在的区域被悬空地布置。由此，可以提供悬置布置的体声波谐振器。
在一些实施例中，体声波谐振器为固态贴附式的体声波谐振器(Solid Mounted BAR，SM BAR)。体声波谐振器还可包括衬底以及设置在所述压电层的下表面和所述衬底之间的至少一个布拉格反射层叠体，所述层叠体包括由具有不同声阻抗材料制成的第一低声阻抗膜和第二高声阻抗膜。
在本公开的第二方面，提供了一种谐振器，包括包括如上第一方面任一项所述的谐振器。
应当理解，发明内容部分中所描述的内容并非旨在限定本公开的关键或重要特征，亦非用于限制本公开的范围。本公开的其他特征通过以下的描述将变得容易理解。
附图说明
通过参考附图阅读下文的详细描述，本公开的实施例的上述以及其他目的、特征和优点将变得容易理解。在附图中，以示例性而非限制性的方式示出了本公开的若干实施例。
图1示出了根据本公开的第一实施例的示例的FBAR的立体示意图。
图2示出了根据本公开的第一实施例的示例的FBAR的俯视示意图。
图3示出了根据本公开的第一实施例的示例的FBAR器的局部放大示意图。
图4示出了图3所示实施例沿A-A’线的剖视图。
图5示出了图3所示实施例沿B-B’线的剖视图。
图6示出了图3所示实施例沿C-C’线的剖视图。
图7示出了图3所示实施例沿D-D’线的剖视图。
图8示出了图3所示实施例沿E–E’线的剖视图。
图9示出了根据本公开的第二实施例的示例的FBAR的立体示意图。
图10示出了根据本公开的第二实施例的示例的FBAR的俯视示意图。
图11示出了根据本公开的实施例的声子晶体阵列中的一个声子晶体单元的示意图。
图12示出了根据本公开的实施例的声子晶体单元的不同实现方式的示意图。
图13示出了根据本公开的第三实施例的示例的SM BAR的立体示意图。
图14示出了根据本公开的第三实施例的示例的SM BAR的俯视示意图。
图15示出了根据本公开的三实施例的示例的SM BAR的局部放大示意图。
图16示出了图15所示实施例沿A-A’线的剖视图。
图17示出了图15所示实施例沿B-B’线的剖视图。
图18示出了图15所示实施例沿C-C’线的剖视图。
图19示出了图15所示实施例沿D-D’线的剖视图。
图20示出了图15所示实施例沿E–E’线的剖视图。
图21示出了根据本公开的第四实施例的示例的SM BAR的立体示意图。
图22示出了根据本公开的第四实施例的示例的SM BAR的俯视示意图。
图23-图29示出了根据本公开的实施例的用于制造FBAR的的方法的示意图。
贯穿所有附图，相同或者相似的参考标号被用来表示相同或者相似的组件。
具体实施方式
下文将参考附图中示出的若干示例性实施例来描述本公开的原理和精神。应当理解，描述这些具体的实施例仅是为了使本领域的技术人员能够更好地理解并实现本公开，而并非以任何方式限制本公开的范围。在以下描述和权利要求中，除非另有定义，否则本文中使用的所有技术和科学术语具有与所属领域的普通技术人员通常所理解的含义。
在本文中使用的术语“包括”及其变形表示开放性包括，即“包括但不限于”。除非特别申明，术语“或”表示“和/或”。术语“基于”表示“至少部分地基于”。术语“一个示例实施例”和“一个实施例”表示“至少一个示例实施例”。术语“另一实施例”表示“至少一个另外的实施例”。术语“上”、“下”、“前”、“后”等指示放置或者位置关系的词汇均基于附图所示的方位或者位置关系，仅为了便于描述本公开的原理，而不是指示或者暗示所指的元件必须具有特定的方位、以特定的方位构造或操作，因此不能理解为对本公开的限制。
如背景技术所述，BAR适于在预定的频率操作以将电信号转换成声波信号，接着将声波信号转换成电信号。作为示例，针对5G通信技术，频率范围可在3.3-4.9GHz的范围内。在使用中，发明人发现：尽管BAR实现抑制绝大能量损耗，但依然有少部分能量通过压电平面泄漏，造成一定的损耗，这会影响BAR的操作性能。特别地，在BAR用作滤波器的情况下，滤波器存在一些杂散波，从而影响滤波器的性能。期望，能够进一步降低BAR的损耗，抑制BAR的杂散波。
下面结合附图来说明根据本公开实施例的FBAR。
图1-图8示出根据本公开的一个实施例的FBAR 100的结构示意图。在图1-图8所示的实施例中，FBAR 100被实现为悬置式BAR。如图所示，FBAR 100包括：压电层110和设置于压电层110上的叉指换能器(IDT)。
如图1-图2所示，叉指换能器包括输入输出端、汇流条(busbar)、以及多个叉指电极。输入输出端包括输入端120、输出端130。输入端120和输出端130彼此相对地被布置在压电层110的上表面上。FBAR 100还包括衬底薄膜140和衬底150。衬底薄膜140和衬底150被布置为支撑压电层110。输入端120和输出端130所在的压电层110的区域被悬空地布置。输入端120能够基于逆压电效应将电能量转换成声波形成谐振，输出端130能够基于正压电效应将产生的声波信号转换成电信号进行输出。
在图示的实施例中，输入端120和输出端130被布置在压电层110的上表面的中心处。输入端120包括输入汇流条122和从输入汇流条122突出的多个第一叉指电极124、124’。多个第一叉指电极124、124’被配置成将来自输入汇流条120的第一电信号转换成声波信号。输出端130包括输出汇流条132和从输出汇流条132朝向输入汇流条122突出的多个第二叉指电极134、134’。
多个第二叉指电极134、134’中的每个第二叉指电极与多个第一叉指电极124、124’中的每个第一叉指电极一一对应地相互耦合构成多个叉指电极耦合对，以将声波信号转换成第二电信号。在图示的实施例中，第二叉指电极134与第一叉指电极124相互物理地耦合以形成一个叉指电极对；第二叉指电极134’与第一叉指电极124’相互物理地耦合以形成一个叉指电极对。多个叉指电极耦合对包括相邻设置的第一叉指电极耦合对和第二叉指电极耦合对。为了便于说明，在图中仅示例性地示出了6对彼此耦合的叉指电极，而省略了其他的彼此耦合的叉指电极。值得说明的是，彼此耦合的叉指电极对的数目仅仅是示例性的，并且可以根据谐振器的功率要求设置适当数目的叉指电极对。在图示的实施例中，FBAR 100还可包括地电极170，地电极170围绕压电层110的边缘放置以使得包围输入端120和输出端130。
输入端120和输出端130可由金属导体材料。在一些实施例中，金属导体材料可包括金、铝、铜、银、钼、钨等。压电层110可由压电性能良好的材料制成。在一些实施例中，压电层110的材料可包括铌酸锂、铌酸锂或者氮化铝等，由此实现高耦合系数。衬底150的材质为绝缘材料，并且适于提供良好的稳定性。在一些实施例中，衬底150的材料可包括高阻硅、碳化硅、蓝宝石、金刚石、石英等。在压电层110和衬底150之间的作为过渡层的衬底薄膜140可由低声阻抗材料制成。在一些实施例中，衬底薄膜140的材料可包括二氧化硅(SiO 2)、氮化硅(Si 3N 4)、硅(Si)、铝(Al)、氧化锌(ZnO)等。
体声波谐振器还包括周期性排列的多个声波抑制结构160，每个声波抑制结构160被设置于相邻的第一叉指电极耦合对和所述第二叉指电极耦合对之间。通过设置在相邻的第一叉指电极耦合对和第二叉指电极耦合对之间的多个声波抑制结构160，可以有效地抑制叉指电极附近的杂散声波。由此，FBAR能够将声波能量约束在主模上，提高谐振器的耦合系数和降低损耗。在一些实施例中，相邻的多个叉指电极对中的每个叉指电极对之间均设置有声波抑制结构。在一些实施例中，相邻的多个叉指电极对中的部分叉指电极对之间设置有声波抑制结构之间。
声波抑制结构160可包括多种实现方式。在一些实施例中，声波抑制结构160可被实现为空气孔隙的形式。在图1-图8所示的实施例中，声波抑制结构160被实施为空气孔隙；空气孔隙贯通压电层。在一些实施例中，声波抑制结构160可被实现为声子晶体阵列的形式(稍后将参照图9-图12详细描述)。在其他实施例中，声波抑制结构160也 可以实现为空气孔隙和声子晶体阵列的组合的形式。
在图1-图8所示的实施例中，声波抑制结构160被实现为矩形的空气孔隙。应当理解的是，这仅仅是示例性的，声波抑制结构160可实现为其他任何适当的形状，例如其他多边形、圆形、椭圆形，或能够实现本公开的功能的其他规则或不规则图案。这些形状均涵盖在根据本公开实施例的声波抑制结构160的范围内。
下面结合图1-8所示的实施例，进一步来说明根据本公开实施例的声波抑制结构160的详细示例性布置。
在一些实施例中，如图1-图8所示，声波抑制结构160可被设置于相邻叉指电极耦合对的叉指电极之间的区域的第一声波抑制结构162、162’、166。如图所示，这里的术语“叉指电极之间的区域”是指相邻叉指电极耦合对的相应的叉指电极彼此相邻地延伸的区域。通过第一声波抑制结构162、162’、166，可有效地抑制压电层110中的在叉指电极延伸方向上的分布的杂散模式。在一些实施例中，第一声波抑制结构162、162’、166与叉指电极124、124’、134、134’平行地设置。通过平行设置的第一声波抑制结构162、162’、166，可有效地抑制压电层110中的在纵向方向上分布的杂散纵向模式。
在一些实施例中，声波抑制结构160可被设置于叉指电极末端与汇流条之间的区域。
在图示的实施例中，声波抑制结构160可包括位于第一叉指电极124、124’的末端与输出汇流条132之间的第二声波抑制结构164、164’。由此，通过第二声波抑制结构164、164’，可有效地抑制压电层110中的在第一叉指电极124、124’的末端与输出汇流条132附近分布的杂散模式。在一些实施例中，第二声波抑制结构164、164’与输出汇流条132平行。由此，可有效地抑制压电层110中的在横向方向上分布的杂散横向模式。
在一些实施例中，如图所示，声波抑制结构160可包括位于第二叉指电极134、134’的末端和输入汇流条122之间的第三声波抑制结构168。由此，通过第三声波抑制结构168，可有效地抑制压电层110中的在第二叉指电极134、134’的末端和输入汇流条122附近分布的杂散模式。在一些实施例中，第三声波抑制结构168与输入汇流条122平行。由此，可有效地抑制压电层110中的在横向方向上分布的杂散横向模式。
在一些实施例中，如图所示，相邻设置的所述第一叉指电极耦合对的叉指电极和所述第二叉指电极耦合对的叉指电极相对于叉指电极的延伸方向镜像对称地布置。通过这种镜像对称地布置的叉指电极排列方式，可以进一步抑制杂散模式并且提高叉指电极的耦合效率。
如图所示，输入端120的第一叉指电极124、124’可包括多组成对布置多对第一叉指电极。每对第一叉指电极可包括第一第一叉指电极124和第二第一叉指电极124’。输出端130的第二叉指电极134、134’可包括成对布置的多对第二叉指电极。每对第二叉指电极可包括第一第二叉指电极134和第二第二叉指电极134’。每对第二叉指电极与每对第二叉指电极逐对一一对应地耦合。值得说明的是，尽管在图示的实施例中，每组第一叉指电极成对设置，这仅仅是示例性的。在其他未示出的实施例中，每组第一叉指电极可包括两对叉指电极或者两个以上的叉指电极。
在一些实施例中，如图所示，输入端120的每对第一叉指电极和输出端130的每对第二叉指电极按照第一第一叉指电极124、第一第二叉指电极134、第二第二叉指电极134’、第二第一叉指电极124’的顺序被配置在压电层110上。按照这样的镜像对称布置的叉指结构可以有效地利用输入端120的第一叉指电极的结构对称性以及输出端130 的第二叉指电极的对称性，由此可以进一步增强压电层110中的杂散模式的抑制性能。
值得说明的是，在一些实施例中，彼此相邻设置的所述第一叉指电极耦合对的叉指电极和所述第二叉指电极耦合对的叉指电极相对于叉指电极的延伸方向可以不是按照镜像对称地布置。例如，作为上述实施例的变形，图中未示出，输入端120的每对第一叉指电极和输出端130的每对第二叉指电极按照第一第一叉指电极124、第一第二叉指电极134、第二第一叉指电极124’、第二第二叉指电极134’的顺序被配置在压电层110上。
在一些实施例中，在第一叉指电极124的外侧(即图2中的左侧)的声波抑制结构162与在第一叉指电极124’(即图2中的右侧)外侧的声波抑制结构162’可关于FBAR的声波传播方向对称布置。通过对称布置的声波抑制结构162、162’，可以进一步抑制压电膜110中的杂散模式。在一些实施例中，如图所示，声波抑制结构164、164’可关于FBAR的声波传播方向对称布置。通过对称布置的声波抑制结构164、164’，可以进一步抑制压电膜110中的杂散模式。
在一些实施例中，图1-图8所述的声波抑制结构160的空气气隙被软质材料取代。软质材料包括密度相对较小且弹性系数小的填充材料，例如二氧化硅等进行填充。软质填充物例如可包括也可以实现类似的性能。
图9-图10示出根据本公开的第二实施例的示例的FBAR 200的立体示意图。图9和图10所示的FBAR 200与图1-图8所示的FBAR 100类似，FBAR 200被实现为悬置式FBAR。FBAR 200的结构与FBAR 100类似，不同之处仅在于，图9-图10的实施例中FBAR 200的声波抑制结构260不同于图1-图8中实施例中FBAR 100的声波抑制结构160。在图9-图10的实施例中，与图1-图8相似的部件以具有相似后缀的附图标记进行编码。处于简化说明的方便，重点描述FBAR 200的结构与FBAR 100的不同之处。
如图9-图10所示，FBAR 200包括：压电层210、输入端220、输出端230、衬底薄膜240和衬底250。输入端220和输出端230彼此相对地被布置在压电层210的上表面上。衬底薄膜240和衬底250被布置为支撑压电层210。输入端220能够基于逆压电效应将电能量转换成声波形成谐振，输出端230能够基于正压电效应将产生的声波信号转换成电信号进行输出。
输入端220包括输入汇流条222和从输入汇流条222突出的多个第一叉指电极224、224’。输出端130包括输出汇流条232和从输出汇流条232朝向输入汇流条222突出的多个第二叉指电极234、234’。在图示的实施例中，第二叉指电极234与第一叉指电极224相互物理地耦合以形成一个叉指电极对；第二叉指电极234’与第一叉指电极224’相互物理地耦合以形成一个叉指电极对。地电极270围绕压电层210的边缘放置以使得包围输入端220和输出端230。
体声波谐振器还包括周期性排列的多个声波抑制结构260，声波抑制结构260被设置于第一叉指电极耦合对和第二叉指电极耦合对之间。通过邻近相应叉指电极设置的声波抑制结构260，叉指电极附近的杂散声波能够被有效地抑制。由此，FBAR 200能够将声波能量约束在主模上，提高谐振器的耦合系数和降低损耗。
在图9-图10的实施例中，声波抑制结构260被实现为空气孔隙268、264、264’和声子晶体阵列262、262’、266的组合的形式。在一些实施例中，如图9-图10所示，声波抑制结构260可包括第一叉指电极耦合对和第二叉指电极耦合对的相邻叉指电极之间 的第一声波抑制结构262、262’、266。通过第一声波抑制结构262、262’、266，可有效地抑制压电层210中的在叉指电极的延伸方向上分布的杂散模式。在一些实施例中，第一声波抑制结构262、262’与叉指电极224、224’、234、234’平行地设置。通过平行设置的第一声波抑制结构262、262’，可有效地抑制压电层210中的在纵向方向上分布的杂散纵向模式。
在一些实施例中，声波抑制结构260可被设置于叉指电极末端与汇流条之间的区域。
在一些实施例中，如图所示，声波抑制结构260可包括位于第一叉指电极224、224’的末端与输出汇流条232之间的第二声波抑制结构264、264’。通过第二声波抑制结构264、264’，可有效地抑制压电层210中的在第一叉指电极224、224’的末端与输出汇流条232附近分布的杂散模式。在一些实施例中，第二声波抑制结构264、264’与输出汇流条232平行。由此，可有效地抑制压电层210中的在横向方向上分布的杂散横向模式。
在一些实施例中，如图所示，声波抑制结构260可包括位于第二叉指电极234、234’的末端和输入汇流条222之间的第三声波抑制结构268。由此，通过第三声波抑制结构268，可有效地抑制压电层210中的在第二叉指电极234、234’的末端和输入汇流条222附近分布的杂散模式。在一些实施例中，第三声波抑制结构268与输入汇流条222平行。由此，可有效地抑制压电层210中的在横向方向上分布的杂散横向模式。
在一些实施例中，如图所示，输入端220的第一叉指电极224、224’可包括多组成对布置多对第一叉指电极。每对第一叉指电极可包括第一第一叉指电极224和第二第一叉指电极224’。输出端230的第二叉指电极234、234’可包括成对布置的多对第二叉指电极。每对第二叉指电极可包括第一第二叉指电极234和第二第二叉指电极234’。值得说明的是，尽管在图示的实施例中，每组第一叉指电极成对设置，这仅仅是示例性的。在其他未示出的实施例中，每组第一叉指电极可包括两对叉指电极或者两个以上的叉指电极。
在一些实施例中，如图所示，输入端220的每对第一叉指电极和输出端230的每对第二叉指电极按照第一第一叉指电极224、第一第二叉指电极234、第二第二叉指电极234’、第二第一叉指电极224’的顺序被配置在压电层210上。按照这样的镜像对称布置的叉指结构可以有效地利用输入端220的第一叉指电极的结构对称性以及输出端230的第二叉指电极的对称性，由此可以进一步增强压电层210中的杂散模式的抑制性能。在一些实施例中，声波抑制结构260可包括对称布置的多个声波抑制结构。
声子晶体阵列可包括多个声子晶体单元265、265a、265b，多个声子晶体单元以各种图案的方式布置。声子晶体单元可包括多种实现方式。通过多个声子晶体单元可以实现声波过滤的同时满足声波抑制结构的刚性要求，进而进一步提高FBAR的耐久性。
值得说明的是，尽管在图示的实施例中，声波抑制结构262、262’、266被示出为声子晶体阵列；而声波抑制结构268、264、264’被示出为空气气隙；这仅仅是示例性的，声波抑制结构260可以设置声子晶体阵列、空气气隙或其组合的任何布置方式。
图11示出声子晶体单元265的一种示例。如图11所示，声子晶体单元265可通过在压电层中形成多个空气气隙来形成。空气气隙可具有各种形状。如图11所示，每个声子晶体单元265可为边长为a1的正方形形状；空气气隙被形成为交叉十字形的形状，交叉十字形的短边的宽度可为0.25a1、长边可为0.95a1。a1可根据带宽频率来选择或调节，以满足所需的声波滤波性能。空气气隙的尺寸也可以根据带宽频率来选择或调节，以满 足所需的声波滤波性能。在一些实施例中，声子晶体单元265的形状关于声波传播方向对称，以进一步增强滤波性能。
图12示出声子晶体单元265的其他不同实施例。声子晶体单元265可以空气为声波边界面，也可以不同于声阻的材料来形成。在一些实施例中，声子晶体阵列为包括多个声子晶体单元的第一声子阵列，多个声子晶体单元包括形成在压电层中的孔图案。在一些实施例中，声子晶体阵列为包括多个声子晶体单元的第二声子阵列，其中多个声子晶体单元位于压电层上，多个声子晶体单元材料的声阻不同于所述压电层材料的声阻。
如图12的左侧所示，声子晶体单元265a可被形成为压电层的上表面上，并且由声阻不同于压电层的声阻的材料形成。声子晶体单元265a可实现为各种形状。如图所示，声子晶体单元265a可包括多种形状图案的组合，作为示例矩形、正方形、圆形、菱形、椭圆形等等。在一些情况下，声子晶体单元265a可包括不规则图案或规则图案的各种组合。在一些实施例中，声子晶体单元265a的形状关于声波传播方向对称，以进一步增强滤波性能。声子晶体单元265a的尺寸可以根据带宽频率来选择或调节，
如图12的右侧所示，声子晶体单元265b可被形成为以空气为声波边界面。声子晶体单元265a可通过在压电层中形成各种空气气隙来形成。空气气隙可以为各种形状。图所示，声子晶体单元265b可包括多种形状图案的组合，作为示例圆形、十字形等等或其组合的形状。声子晶体单元265b的尺寸可以根据带宽频率来选择或调节.在一些实施例中，声子晶体单元265b的形状关于声波传播方向对称，以进一步增强滤波性能。
图13-图20示出根据本公开的第三实施例的示例的SM BAR 300的立体示意图。图13和图20所示的SM BAR 300与图1-图8所示的SM BAR 100类似。不同之处在于，SM BAR300被实现为固态贴附式(Solid Mounted)SM BAR。在图13-图20的实施例中，与图1-图8相似的部件以具有相似后缀的附图标记进行编码。处于简化说明的方便，重点描述SM BAR 300的结构与SM BAR 100的不同之处。
图13-图20示出根据本公开的一个实施例的SM BAR 300的结构示意图。在图13-图20所示的实施例中，SM BAR 300被实现为固态贴附式SM BAR。如图所示，SM BAR300包括：压电层310、输入端320、输出端330、布拉格反射层叠体380和衬底350。输入端320和输出端330彼此相对地被布置在压电层310的上表面上。输入端320能够基于逆压电效应将电能量转换成声波形成谐振，输出端330能够基于正压电效应将产生的声波信号转换成电信号进行输出。层叠体380包括由具有不同声阻抗材料制成的第一低声阻抗膜382a，382b第二高声阻抗膜384a，384b的多个层叠体。在一些实施例中，这些布拉格反射层叠体可以至少两个。通过使用高声阻抗和低声阻抗材料交替叠加形成的布拉格反射层叠体，将主模能量最大效率地限制在压电层中。高声阻抗材料通常可以选择钨(W)、氮化铝(AlN)、钌(Ru)等；低声阻抗薄膜材料通常可以选择二氧化硅(SiO2)、氮化硅(Si3N4)、硅(Si)、铝(Al)、氧化锌(ZnO)等。
在图示的实施例中，输入端320和输出端330被布置在压电层310的上表面的中心处。输入端320包括输入汇流条322和从输入汇流条322突出的多个第一叉指电极324、324’。多个第一叉指电极324、324’被配置成将来自输入汇流条320的第一电信号转换成声波信号。输出端330包括输出汇流条332和从输出汇流条332朝向输入汇流条322突出的多个第二叉指电极334、334’。第二叉指电极334与第一叉指电极324相互物理地耦合以形成一个叉指电极对；第二叉指电极334’与第一叉指电极324’相互物理地耦合 以形成一个叉指电极对。多个第二叉指电极334、334’中的每个第二叉指电极与多个第一叉指电极324、324’中的每个第一叉指电极一一对应地相互耦合构成多个叉指电极耦合对。在图示的实施例中，SM BAR 300还可包括地电极370，地电极370围绕压电层310的边缘放置以使得包围输入端320和输出端330。
在图示的实施例中，体声波谐振器还包括周期性排列的多个声波抑制结构360，声波抑制结构360被设置于第一叉指电极耦合对和第二叉指电极耦合对之间。通过邻近相应叉指电极设置的声波抑制结构360，叉指电极附近的杂散声波能够被有效地抑制。由此，SM BAR 300能够将声波能量约束在主模上，提高谐振器的耦合系数和降低损耗。
声波抑制结构360可包括多种实现方式。在一些实施例中，声波抑制结构360可被实现为空气孔隙的形式，例如其中空气孔隙可贯通压电层设置。在图13-图20所示的实施例中，声波抑制结构360被实施为空气孔隙。在一些实施例中，声波抑制结构360可被实现为声子晶体阵列的形式(稍后将参照图21-图22详细描述)。
在一些实施例中，如图13-图20所示，声波抑制结构360可包括被设置于在第一叉指电极耦合对和第二叉指电极耦合对的相邻叉指电极之间的区域的第一声波抑制结构362、362’、366。由此，通过第一声波抑制结构362、362’、366，可有效地抑制压电层310中的在在叉指电极延伸方向上分布的杂散模式。在一些实施例中，第一声波抑制结构362、362’、366与叉指电极324、324’、334、334’平行地设置。通过平行设置的第一声波抑制结构362、362’、366，可有效地抑制压电层310中的在纵向方向上分布的杂散纵向模式。
在一些实施例中，如图所示，声波抑制结构360可包括位于第一叉指电极324、324’的末端与输出汇流条332之间的第二声波抑制结构364、364’。由此，通过第二声波抑制结构364、364’，可有效地抑制压电层310中的在第一叉指电极324、324’的末端与输出汇流条332附近分布的杂散模式。在一些实施例中，第二声波抑制结构364、364’与输出汇流条332平行。由此，可有效地抑制压电层310中的在横向方向上分布的杂散横向模式。
在一些实施例中，如图所示，声波抑制结构360可包括位于第二叉指电极334、334’的末端和输入汇流条322之间的第三声波抑制结构368。由此，通过第三声波抑制结构368，可有效地抑制压电层310中的在第二叉指电极334、334’的末端和输入汇流条322附近分布的杂散模式。在一些实施例中，第三声波抑制结构368与输入汇流条322平行。由此，可有效地抑制压电层310中的在横向方向上分布的杂散横向模式。
在一些实施例中，如图所示，输入端320的第一叉指电极324、324’可包括多组成对布置多对第一叉指电极。每对第一叉指电极可包括第一第一叉指电极324和第二第一叉指电极324’。输出端330的第二叉指电极334、334’可包括成对布置的多对第二叉指电极。每对第二叉指电极可包括第一第二叉指电极334和第二第二叉指电极334’。值得说明的是，尽管在图示的实施例中，每组第一叉指电极成对设置，这仅仅是示例性的。在其他未示出的实施例中，每组第一叉指电极可包括两对叉指电极或者两个以上的叉指电极。
在一些实施例中，如图所示，输入端320的每对第一叉指电极和输出端330的每对第二叉指电极按照第一第一叉指电极324、第一第二叉指电极334、第二第二叉指电极334’、第二第一叉指电极324’的顺序被配置在压电层310上。按照镜像对称布置的叉 指电极结构可以有效地利用输入端320的第一叉指电极的结构对称性以及输出端330的第二叉指电极的对称性，由此可以进一步增强压电层310中的杂散模式的抑制性能。在一些实施例中，声波抑制结构360可包括对称布置的多个声波抑制结构。
在一些实施例中，声波抑制结构362、362’可关于SM BAR的声波传播方向对称布置。通过对称布置的声波抑制结构362、362’，可以进一步抑制压电层310中的杂散模式。
在一些实施例中，声波抑制结构364、364’可关于SM BAR的声波传播方向对称布置。通过对称布置的声波抑制结构364、364’，可以进一步抑制压电层310中的杂散模式。
在一些实施例中，图13-图20所述的声波抑制结构360的空气气隙被软质材料取代。软质材料包括密度相对较小且弹性系数小的填充材料，例如二氧化硅等进行填充。软质填充物例如可包括也可以实现类似的性能。
图21-图22示出根据本公开的第四实施例的示例的SM BAR 400的立体示意图。图21-图22所示的SM BAR 400与图13-图20所示的SM BAR 300类似；不同之处仅在于，图21-图22的实施例中SM BAR 400的声波抑制结构460不同于图21-图22中实施例中SM BAR 300的声波抑制结构360。在图21-图22的实施例中，与图13-图20相似的部件以具有相似后缀的附图标记进行编码。处于简化说明的方便，重点描述SM BAR400的结构与SM BAR 300的不同之处。
如图21-图22所示，SM BAR 400包括：压电层410、输入端420、输出端430、布拉格反射层叠体480和衬底450。层叠体480包括由具有不同声阻抗材料制成的第一低声阻抗膜482a，482b第二高声阻抗膜484a，484b的多个层叠体。通过使用高声阻抗和低声阻抗材料交替叠加形成的布拉格反射层叠体，将主模能量最大效率地限制在压电层中。
输入端420包括输入汇流条422和从输入汇流条422突出的多个第一叉指电极424、424’。输出端130包括输出汇流条432和从输出汇流条432朝向输入汇流条422突出的多个第二叉指电极434、434’。第二叉指电极434与第一叉指电极424相互物理地耦合以形成一个叉指电极对；第二叉指电极434’与第一叉指电极424’相互物理地耦合以形成一个叉指电极对。多个第二叉指电极434、434’中的每个第二叉指电极与多个第一叉指电极424、424’中的每个第一叉指电极一一对应地相互耦合构成多个叉指电极耦合对。地电极470围绕压电层410的边缘放置以使得包围输入端420和输出端430。
在图示的实施例中，体声波谐振器还包括周期性排列的多个声波抑制结构460，声波抑制结构460被设置于第一叉指电极耦合对和第二叉指电极耦合对之间。通过邻近相应叉指电极设置的声波抑制结构460，叉指电极附近的杂散声波能够被有效地抑制。由此，SM BAR 400能够将声波能量约束在主模上，提高谐振器的耦合系数和降低损耗。声波抑制结构460被实现为空气孔隙468、464、464’和声子晶体阵列462、462’、466的组合的形式。值得说明的是，这仅仅是示例性的，声波抑制结构460也可以全部实现为声子晶体阵列的形式。
声子晶体阵列可包括多个声子晶体单元，多个声子晶体单元以各种图案的方式布置。声子晶体单元可包括多种实现方式。通过多个声子晶体单元可以实现声波过滤的同时满足声波抑制结构的刚性要求，进而进一步提高SM BAR的耐久性。声子晶体阵列可与图10中所设置的声子晶体阵列类似，省略对其详细说明。值得说明的是，尽管在图示的实施例中，声波抑制结构462、462’、466被示出为声子晶体阵列；而声波抑制结构468、 464、464’被示出为空气气隙；这仅仅是示例性的，声波抑制结构460可以设置声子晶体阵列、空气气隙或其组合的任何布置方式。
本申请实施例提供一种滤波器，其包括上述任一方面所述的谐振器。这些滤波器可以被设置在电子设备中用于针对信号进行处理。例如，在一些实施例中，电子设备中设置有印刷线路板(printed circuit board，PCB)以及与印刷线路板连接的电子器件；其中，该电子器件中设置有谐振器；本申请对于该电子器件的设置形式不做限制；示意地，在一些实施例中，该电子器件可以为滤波器、传感器、变压器等能够产生谐振频率的产品或部件。本申请对上述电子设备的具体设置形式不做限制；例如，该电子设备可以为电视机、手机、电视、平板电脑、笔记本、车载电脑、智能手表、智能手环、卫星通讯设备等电子产品。
本申请对于上述电子器件中设置的谐振器的类型不做限制；例如，该谐振器可以为声表面波(surface acoustic wave，SAW)谐振器、兰姆波(lamb)谐振器、微机电***(micro-electro-mechanical system，MEMS)谐振器等。
图23-图29示出了根据本公开的实施例的用于制造图1所示的体声波谐振器100的方法的示意图。如图23所示，首先在衬底150上通过等离子体增强化学的气相沉积法(Plasma Enhanced Chemical Vapor Deposition，PECVD)淀积衬底薄膜140。可选地，对衬底薄膜140进行化学机械抛光(CMP)。用He+离子注入方法处理压电晶片并且对压电晶片进行表面处理，将经处理后的压电晶片与衬底薄膜140键合。然后，例如通过热处理的手段使注入的离子He+形成He2气体，压电晶片剥离得到压电层110，如图24所示。接着，例如通过光刻定义并溅射输入端和输出端图案，并且溅射金属薄膜，利用刻蚀工艺形成输入端120和输出端130，如图25所示。接着，从背侧针对衬底150进行刻蚀，以形成悬空结构；接着，例如通过PECVD沉积保护膜180，如图26所示。接着，定义空气孔隙160的图案，并且刻蚀保护膜180以形成空气孔隙160，如图28所示。最后，释放顶层保护膜180，最终形成体声波谐振器100。
值得说明的是，上述描述顺序仅仅是示例性的而非限制性的。基于本公开的教导，可以由多种用于制造根据本公开实施例的体声波谐振器的方法。此外，尽管以体声波谐振器100为例说明了根据本公开实施例的用于制造体声波谐振器的方法，对于其他实施例中的体声波谐振器可以类似的方法实施。省略对其详细说明。
另外，尽管操作以特定顺序被描绘，但这并不应该理解为要求此类操作以示出的特定顺序或以相继顺序完成，或者执行所有图示的操作以获取期望结果。在某些情况下，多任务或并行处理会是有益的。同样地，尽管上述论述包含了某些特定的实施细节，但这并不应解释为限制任何发明或权利要求的范围，而应解释为对可以针对特定发明的特定实施例的描述。本说明书中在分离的实施例的上下文中描述的某些特征也可以整合实施在单个实施例中。反之，在单个实施例的上下文中描述的各种特征也可以分离地在多个实施例或在任何合适的子组合中实施。
尽管已经以特定于结构特征和/或方法动作的语言描述了主题，但是应当理解，所附权利要求中限定的主题并不限于上文描述的特定特征或动作。相反，上文描述的特定特征和动作是作为实现权利要求的示例形式而被公开的。

Claims (12)

  1. 一种体声波谐振器，其特征在于，包括：
    压电层；以及叉指换能器(IDT)，所述叉指换能器设置于所述压电层上；
    所述叉指换能器包括输入输出端、汇流条、以及多个叉指电极，所述输入输出端包括输入端和输出端，所述汇流条包括输入汇流条和输出汇流条，所述多个叉指电极包括多个第一叉指电极和多个第二叉指电极，所述输入端与所述输入汇流条连接，所述输入汇流条与所述多个第一叉指电极连接，所述输出端与所述输出汇流条连接，所述输出汇流条与所述多个第二叉指电极连接，所述多个第二叉指电极中的每个第二叉指电极与所述多个第一叉指电极中的每个第一叉指电极一一对应地相互耦合构成多个叉指电极耦合对；
    其中所述体声波谐振器还包括周期性排列的多个声波抑制结构，所述多个声波抑制结构中的每个声波抑制结构被设置于相邻叉指电极耦合对之间。
  2. 根据权利要求1所述的体声波谐振器，其特征在于，所述多个声波抑制结构中的至少一个包括空气孔隙，其中所述空气孔隙贯通所述压电层。
  3. 根据权利要求1所述的体声波谐振器，其特征在于，所述多个声波抑制结构中的至少一个包括第一声子晶体阵列，其中所述第一声子晶体阵列包括多个声子晶体单元，所述多个声子晶体单元包括形成在压电层中的孔图案。
  4. 根据权利要求1所述的体声波谐振器，其特征在于，所述多个声波抑制结构中的至少一个包括第二声子晶体阵列，其中所述第二声子晶体阵列包括多个声子晶体单元，所述多个声子晶体单元位于所述压电层上，所述多个声子晶体单元材料的声阻不同于所述压电层材料的声阻。
  5. 根据权利要求1所述的体声波谐振器，其特征在于，所述多个声波抑制结构中的至少一个声波抑制结构被设置于所述相邻叉指电极耦合对的相邻叉指电极之间的区域。
  6. 根据权利要求5所述的体声波谐振器，其特征在于，所述至少一个声波抑制结构与所述叉指电极的延伸方向平行地设置。
  7. 根据权利要求1所述的体声波谐振器，其特征在于，所述多个声波抑制结构中的至少一个声波抑制结构被设置于所述相邻叉指电极耦合对的叉指电极末端与所述汇流条之间的区域。
  8. 根据权利要求7所述的体声波谐振器，其中所述至少一个声波抑制结构与所述汇流条的延伸方向平行地设置。
  9. 根据权利要求1所述的体声波谐振器，其特征在于，相邻设置的第一叉指电极耦合对的叉指电极和第二叉指电极耦合对的叉指电极相对于叉指电极的延伸方向镜像对称地布置。
  10. 根据权利要求1所述的体声波谐振器，其特征在于，所述体声波谐振器为FBAR。
  11. 根据权利要求1所述的体声波谐振器，其特征在于，所述体声波谐振器为SM BAR。
  12. 一种滤波器，其特征在于，包括如权利要求1-11中任一项所述的谐振器。
PCT/CN2021/127146 2021-10-28 2021-10-28 体声波谐振器和滤波器 WO2023070457A1 (zh)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8525619B1 (en) * 2010-05-28 2013-09-03 Sandia Corporation Lateral acoustic wave resonator comprising a suspended membrane of low damping resonator material
CN111697943A (zh) * 2020-07-02 2020-09-22 电子科技大学 一种高频高耦合系数压电薄膜体声波谐振器
CN112491379A (zh) * 2020-10-21 2021-03-12 电子科技大学 一种具有声子晶体反射器的声表面波谐振器
CN113437947A (zh) * 2021-07-06 2021-09-24 电子科技大学 一种基于声子晶体抑制侧边能量辐射的薄膜体声波谐振器
CN113452339A (zh) * 2021-05-20 2021-09-28 电子科技大学 一种压电薄膜体声波谐振器

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Publication number Priority date Publication date Assignee Title
US8525619B1 (en) * 2010-05-28 2013-09-03 Sandia Corporation Lateral acoustic wave resonator comprising a suspended membrane of low damping resonator material
CN111697943A (zh) * 2020-07-02 2020-09-22 电子科技大学 一种高频高耦合系数压电薄膜体声波谐振器
CN112491379A (zh) * 2020-10-21 2021-03-12 电子科技大学 一种具有声子晶体反射器的声表面波谐振器
CN113452339A (zh) * 2021-05-20 2021-09-28 电子科技大学 一种压电薄膜体声波谐振器
CN113437947A (zh) * 2021-07-06 2021-09-24 电子科技大学 一种基于声子晶体抑制侧边能量辐射的薄膜体声波谐振器

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