WO2024046099A1 - 兰姆波谐振器及制备方法、滤波器、射频模组、电子设备 - Google Patents

兰姆波谐振器及制备方法、滤波器、射频模组、电子设备 Download PDF

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Publication number
WO2024046099A1
WO2024046099A1 PCT/CN2023/112727 CN2023112727W WO2024046099A1 WO 2024046099 A1 WO2024046099 A1 WO 2024046099A1 CN 2023112727 W CN2023112727 W CN 2023112727W WO 2024046099 A1 WO2024046099 A1 WO 2024046099A1
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Prior art keywords
layer
lamb wave
wave resonator
piezoelectric layer
interdigital transducer
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PCT/CN2023/112727
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English (en)
French (fr)
Inventor
陶翔
蒋欣
唐戴平
古健
柯汉
栾仲智
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华为技术有限公司
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Publication of WO2024046099A1 publication Critical patent/WO2024046099A1/zh

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02228—Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • 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

Definitions

  • the present application relates to the field of radio frequency technology, and in particular to a Lamb wave resonator and preparation method, filter, radio frequency module, and electronic equipment.
  • the current RF front-end resonators mainly include surface acoustic wave (SAW) resonators and bulk acoustic wave (BAW) resonators.
  • SAW surface acoustic wave
  • BAW bulk acoustic wave
  • the frequency of the SAW resonator is lower than 3.5GHz, and the electromechanical coupling coefficient is only about 10%.
  • the electromechanical coupling coefficient of BAW resonators is also smaller.
  • Lamb wave resonators have become a research hotspot in recent years because of their advantages such as high sound speed and large electromechanical coupling coefficient (up to 25%).
  • Embodiments of the present application provide a Lamb wave resonator and a preparation method, a filter, a radio frequency module, and an electronic device, which are used to provide a high-performance lamb wave resonator.
  • a first aspect of the embodiment of the present application provides a Lamb wave resonator.
  • the lamb wave resonator serves as a filter element and can be applied to radio frequency devices.
  • the lamb wave resonator includes: substrate, piezoelectric layer, interdigital transducer and dielectric layer.
  • the piezoelectric layer is arranged on the substrate, and the interdigital transducer and the dielectric layer are arranged on the side of the piezoelectric layer away from the substrate.
  • the interdigital transducer includes a plurality of first electrode fingers and a plurality of second electrode fingers.
  • the plurality of first electrode fingers and the plurality of second electrode fingers are alternately arranged along a first direction; the first direction and the first electrode fingers are The extending directions of the second electrode fingers intersect.
  • the dielectric layer includes a first part, which is disposed on the surface of the piezoelectric layer and located at the periphery of the first electrode finger and the second electrode finger. That is, the first part is located at the gap of the IDT.
  • the dielectric layer can be used as a frequency shifting layer, a temperature compensation layer or a passivation layer at the same time.
  • the lamb wave resonator provided by the embodiment of the present application can suppress the A0 mode transverse harmonics and S0 in the lamb wave resonator by thinning the thickness S2 of the second part of the dielectric layer located above the interdigital transducer.
  • the effect of plate wave spurious modes such as modal transverse high-order harmonics improves the flatness within the passband, reduces losses, and improves the performance of lamb wave resonators.
  • the lamb wave resonator provided by the embodiment of the present application thins the thickness of the second part of the dielectric layer located above the interdigital transducer, which is equivalent to processing the dielectric layer.
  • the lamb wave resonator provided by the embodiments of the present application has a simple preparation process, low process difficulty, and large process tolerance, which can improve the yield of the lamb wave resonator.
  • the lamb wave resonator provided in the embodiment of the present application has a relatively good suppression effect on plate wave spurious modes such as A0 mode transverse high-order harmonics and S0 mode transverse high-order harmonics.
  • the lamb wave resonator usually includes a layer of frequency shifting layer or passivation made of dielectric material. layer.
  • the frequency shifting layer or the passivation layer can be directly used as the dielectric layer in the lamb wave resonator provided by the embodiment of the present application, and the frequency shifting layer or the passivation layer can be processed without adding a new film layer.
  • the changes to the lamb wave resonator are minor.
  • the dielectric layer further includes a second part, and the second part is located on the top surface of the interdigital transducer; the thickness of the first part is S1, and the thickness of the second part is S2, S1>S2.
  • a thinner dielectric layer can also be placed above the interdigital transducer.
  • the second part can be thinned to achieve different thicknesses in the lamb wave resonator. Suppression of A0 mode transverse harmonics and S0 mode transverse harmonics.
  • S1-S2 ⁇ 50nm.
  • the thickness of the first part is S1, and 20nm ⁇ S1 ⁇ 200nm.
  • the thickness of the first part of the dielectric layer is S1, and 20nm ⁇ S1 ⁇ 200nm.
  • S1-S2 ⁇ 65nm; 110nm ⁇ S1 ⁇ 140nm.
  • the thickness of the interdigital transducer ranges from 60 nm to 140 nm.
  • the thickness of the interdigital transducer in the lamb wave resonator provided by the embodiment of the present application has a wide range of values.
  • the lamb wave resonator can be applied to scenarios that require different thicknesses of the interdigital transducer, and has a wide range of applications.
  • the first part is flush with the top surface of the second part. This is one possible structure.
  • the top surface of the first part is higher than the top surface of the second part. This is one possible structure.
  • the top surface of the first part is lower than the top surface of the second part. This is one possible structure.
  • the second portion has a first projection on the piezoelectric layer
  • the interdigital transducer has a second projection on the piezoelectric layer
  • the second projection includes the first projection.
  • the second part is aligned with the interdigital transducer structure, and has a better suppression effect on the A0 mode transverse high-order harmonics and the S0 mode transverse high-order harmonics.
  • the lamb wave resonator further includes a passivation layer.
  • the passivation layer is provided on the side of the dielectric layer away from the piezoelectric layer.
  • the thickness of the passivation layer ranges from 1 nm to 50 nm.
  • the material of the dielectric layer includes SiO 2 , Si 3 N 4 or Al 2 O 3 . This is one possible way to do it.
  • the lamb wave resonator also includes an acoustic wave reflection layer.
  • the acoustic wave reflection layer is arranged on the side of the piezoelectric layer away from the interdigital transducer; the acoustic wave reflection coefficient of the surface of the acoustic wave reflection layer facing the piezoelectric layer is R. ,0.5 ⁇ R ⁇ 0.86.
  • the acoustic wave reflection layer is provided on the side of the piezoelectric layer close to the substrate, and the acoustic impedance of the acoustic wave reflection layer is smaller than the acoustic impedance of the piezoelectric layer.
  • the sound waves excited by the lamb wave resonator will be reflected on the surface of the sound wave reflection layer facing the piezoelectric layer and reflected back to the piezoelectric layer.
  • the acoustic wave can be locked in the piezoelectric layer, thus avoiding the serious degradation of device performance caused by a large amount of acoustic waves excited by the lamb wave resonator leaking to the substrate.
  • the acoustic wave reflection layer replaces the traditional air cavity and Bragg reflection structure, without the need to dig out a cavity or form a complex Bragg reflection structure, simplifying the preparation process of lamb wave resonators and reducing the difficulty of preparing lamb wave resonators.
  • the mechanical strength of the lamb wave resonator can be enhanced and the yield of the lamb wave resonator can be improved.
  • the material selection range of the sound wave reflection layer is wide, the sound wave reflection coefficient R of the sound wave reflection layer of each material is different, and the thickness of the sound wave reflection layer of each material is also different.
  • the thickness of the acoustic reflective layer is 3.5 ⁇ m-30 ⁇ m. This is a thickness range that is convenient for mass production.
  • the material of the sound wave reflection layer is a polymer material.
  • the sound wave reflection layer in the embodiment of the present application has a wide range of material selection and is easy to implement.
  • the material of the sound wave reflection layer includes polyimide, polydimethylsiloxane, polymethyl methacrylate, polyvinylidene fluoride, or polyethylene terephthalate.
  • polyimide polydimethylsiloxane
  • polymethyl methacrylate polymethyl methacrylate
  • polyvinylidene fluoride polyvinylidene fluoride
  • polyethylene terephthalate polyethylene terephthalate
  • the sound wave reflection layer has a single film layer structure.
  • the sound wave reflection layer with a single film layer structure has a simple structure and Simple process.
  • a second aspect of the embodiment of the present application provides a filter including a plurality of cascaded lamb wave resonators; wherein the lamb wave resonator is any of the lamb wave resonators of the first aspect.
  • the filter provided in the second aspect of the embodiment of the present application includes the lamb wave resonator of the first aspect, and its beneficial effects are the same as those of the lamb wave resonator, which will not be described again here.
  • a third aspect of the embodiment of the present application provides a radio frequency module, including a filter and a power amplifier.
  • the filter is coupled to the power amplifier; the filter is the filter of the second aspect.
  • the radio frequency module provided in the third aspect of the embodiment of the present application includes the lamb wave resonator of the first aspect, and its beneficial effects are the same as those of the lamb wave resonator, which will not be described again here.
  • a fourth aspect of the embodiments of the present application provides an electronic device, including a filter and a circuit board.
  • the filter is disposed on the circuit board; the filter is the filter of the second aspect.
  • the electronic device provided in the fourth aspect of the embodiment of the present application includes the lamb wave resonator of the first aspect, and its beneficial effects are the same as those of the lamb wave resonator, which will not be described again here.
  • a fifth aspect of the embodiment of the present application provides a method for preparing a lamb wave resonator, including: forming a piezoelectric layer; forming an interdigital transducer on one side of the piezoelectric layer; and the interdigital transducer includes a plurality of One electrode finger and a plurality of second electrode fingers, the plurality of first electrode fingers and the plurality of second electrode fingers are alternately arranged along a first direction; the first direction intersects the extension direction of the first electrode finger and the second electrode finger; A dielectric layer is formed on one side of the piezoelectric layer, and the dielectric layer and the interdigital transducer are located on the same side of the piezoelectric layer; the dielectric layer includes a first part, which is disposed on the surface of the piezoelectric layer and located on the first electrode finger and The second electrode refers to the periphery.
  • the preparation method of the lamb wave resonator provided by the embodiment of the present application can form the dielectric layer required by the embodiment of the present application by controlling the process when forming the dielectric layer, so as to provide a method that can suppress the A0 mode transverse high-order harmonics and S0 mode transverse high-order harmonic lamb wave resonator.
  • the process for processing dielectric materials is simple, easy to implement, and has a high yield rate.
  • the dielectric layer further includes a second part, and the second part is located on the top surface of the interdigital transducer; the thickness of the first part is greater than the thickness of the second part; the dielectric layer is formed on one side of the piezoelectric layer,
  • the method includes: after forming the interdigital transducer, forming a first dielectric film on the side of the interdigital transducer away from the piezoelectric layer; the first dielectric film covers the interdigital transducer and the piezoelectric layer; forming on the first dielectric film The second dielectric film is located on the periphery of the first electrode finger and the second electrode finger to form a dielectric layer; the portion of the first dielectric film located on the surface of the piezoelectric layer and the second dielectric film constitute the first part, and the first dielectric film The portion of the membrane located on the top surface of the IDT serves as the second part.
  • the dielectric layer further includes a second part, and the second part is located on the top surface of the interdigital transducer; the thickness of the first part is greater than the thickness of the second part; the dielectric layer is formed on one side of the piezoelectric layer, It includes: after forming the interdigital transducer, forming a third dielectric film on the side of the interdigital transducer away from the piezoelectric layer; the third dielectric film covers the interdigital transducer and the piezoelectric layer; and the third dielectric film is located on the interdigital transducer.
  • the top surface of the transducer is thinned to form a dielectric layer; the part of the third dielectric film located on the surface of the piezoelectric layer is the first part, and the thinned part of the third dielectric film is the second part.
  • the thickness of the first part is S1
  • the thickness of the second part is S2, S1>S2.
  • a thinner dielectric layer can also be placed above the interdigital transducer.
  • the second part can be thinned to achieve different thicknesses in the lamb wave resonator. Suppression of A0 mode transverse harmonics and S0 mode transverse harmonics.
  • S1-S2 ⁇ 50nm.
  • the second portion has a first projection on the piezoelectric layer
  • the interdigital transducer has a second projection on the piezoelectric layer
  • the second projection includes the first projection.
  • the second part is aligned with the interdigital transducer structure, and has a better suppression effect on the A0 mode transverse high-order harmonics and the S0 mode transverse high-order harmonics.
  • Figure 1 is a schematic framework diagram of an electronic device provided by an embodiment of the present application.
  • Figure 2 is a schematic diagram of the topological structure of the filter provided by the embodiment of the present application.
  • Figure 3A is a partial structural schematic diagram of a lamb wave resonator illustrating an embodiment of the present application
  • Figure 3B is a schematic diagram of a three-dimensional admittance curve of the lamb wave resonator shown in Figure 3A illustrating an embodiment of the present application;
  • Figure 4A is a partial structural schematic diagram of another lamb wave resonator illustrating an embodiment of the present application.
  • Figure 4B is a partial structural schematic diagram of another lamb wave resonator illustrating an embodiment of the present application.
  • Figure 4C is a schematic diagram of a two-dimensional admittance curve of the lamb wave resonator shown in Figure 4A illustrating an embodiment of the present application;
  • Figure 4D is a schematic diagram of a two-dimensional admittance curve of the lamb wave resonator shown in Figure 4B illustrating an embodiment of the present application;
  • Figure 5A is a schematic structural diagram of a lamb wave resonator provided by an embodiment of the present application.
  • Figure 5B is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 5C is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 5D is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 6A is a schematic top view of an interdigital transducer provided by an embodiment of the present application.
  • Figure 6B is an enlarged view of M in Figure 5D;
  • Figure 7A is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 7B is a schematic top view of a dielectric layer provided by an embodiment of the present application.
  • Figure 8A is an admittance curve comparison diagram provided by an embodiment of the present application.
  • Figure 8B is a schematic diagram of the admittance curve of the lamb wave resonator provided in this embodiment.
  • Figure 9A is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 9B is a schematic top view of another dielectric layer provided by an embodiment of the present application.
  • Figure 9C is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figures 10A-10C are comparison diagrams of the admittance curves of a lamb wave resonator when the thickness of the second part changes according to the embodiment of the present application;
  • Figures 11A-11C are comparison diagrams of the admittance curves of the lamb wave resonator when the thickness of the interdigital transducer changes according to the embodiment of the present application;
  • Figure 12 is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 13 is a schematic structural diagram of another lamb wave resonator provided by an embodiment of the present application.
  • Figure 14 is a schematic diagram of the preparation process of a lamb wave resonator provided by the embodiment of the present application.
  • Figure 15 is a schematic diagram of the preparation steps of a lamb wave resonator provided by an embodiment of the present application.
  • orientation terms such as “upper”, “lower”, “left”, and “right” may include but are not limited to being defined relative to the orientation of the components in the drawings. It should be understood that, These directional terms may be relative concepts and are used for relative description and clarification, which may change accordingly according to changes in the orientation in which components are placed in the drawings.
  • connection should be understood in a broad sense.
  • connection can be a fixed connection, a detachable connection, or an integral body; it can be a direct connection. , can also be connected indirectly through intermediaries.
  • phase coupling may refer to a direct electrical connection or an indirect electrical connection through an intermediate medium.
  • contact can mean direct contact or indirect contact through an intermediary.
  • the electronic equipment is, for example, consumer electronic products, household electronic products, vehicle-mounted electronic products, financial terminal products, and communication electronic products.
  • consumer electronic products include mobile phones, tablets, laptops, e-readers, personal computers (PC), personal digital assistants (PDA), desktop monitors, Smart wearable products (such as smart watches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, drones, etc.
  • Home electronic products include smart door locks, TVs, remote controls, refrigerators, rechargeable small household appliances (such as soymilk machines, sweeping robots), etc.
  • Vehicle-mounted electronic products such as car navigation systems, vehicle-mounted high-density digital video discs (digital video discs, DVDs), etc.
  • Financial terminal products include automated teller machines (ATMs), self-service terminals, etc.
  • Communication electronic products include servers, memories, radars, base stations and other communication equipment.
  • the electronic device is a mobile phone as an example below.
  • the electronic device 1 mainly includes a cover 11 , a display 12 , a middle frame 13 and a rear case 14 .
  • the back shell 14 and the display screen 12 are respectively located on both sides of the middle frame 13 , and the middle frame 13 and the display screen 12 are arranged in the back shell 14 .
  • the cover plate 11 is disposed on the side of the display screen 12 away from the middle frame 13 .
  • the display screen 12 The display surface faces the cover 11.
  • the above-mentioned display screen 12 may be a liquid crystal display (LCD).
  • the liquid crystal display screen includes a liquid crystal display panel and a backlight module.
  • the liquid crystal display panel is disposed between the cover 11 and the backlight module.
  • the backlight The module is used to provide light source for the LCD panel.
  • the above-mentioned display screen 12 may also be an organic light emitting diode (organic light emitting diode, OLED) display screen. Since the OLED display is a self-luminous display, there is no need to set up a backlight module.
  • OLED organic light emitting diode
  • the above-mentioned middle frame 13 includes a bearing plate 131 and a frame 132 surrounding the bearing plate 131 .
  • the above-mentioned electronic device 1 may also include printed circuit boards (PCB), batteries, cameras and other electronic components.
  • PCB printed circuit boards
  • the printed circuit boards, batteries, cameras and other electronic components may be provided on the carrier board 131 .
  • the above-mentioned electronic device 1 may also include a system on chip (SOC), a radio frequency chip, etc. provided on the PCB.
  • SOC system on chip
  • the PCB is used to carry the system on chip, a radio frequency chip, etc., and is electrically connected to the system on chip, a radio frequency chip, etc. .
  • the radio frequency chip can include filters, processors and other parts.
  • the processor is used to process various signals, and the filter is an important part of RF signal processing. It is used to pass signals of specific frequencies and block signals of other frequencies.
  • the embodiment of the present application provides a filter, which can be applied to the above-mentioned electronic device 1, for example, applied to a radio frequency chip in the electronic device 1.
  • the filter provided by the embodiment of the present application can be, for example, a low-pass wave. Filter, high-pass filter, band-pass filter, band-reject filter or active filter, etc.
  • the filter provided by the embodiment of the present application is not limited to being integrated in the electronic device 1 .
  • the filter can also be used as a separate component, or the filter can be integrated with a power amplifier and other components into a module (such as a radio frequency device, radio frequency module, filter module, etc.), and the filter is coupled to the power amplifier. Perform signal processing and transmission.
  • the filter 10 provided by the embodiment of the present application includes a plurality of cascaded Lamb wave (lamb wave) resonators 100.
  • the plurality of Lamb wave (lamb wave) resonators 100 may have different resonant frequencies. , and can be cascaded together in series and parallel.
  • FIG. 2 also illustrates the signal input terminal Vi, the signal output terminal Vo and the ground terminal GND of the filter 10 .
  • the lamb wave resonator 100 has the advantages of high sound speed (for example, 12000m/s-15000m/s) and large electromechanical coupling coefficient (for example, up to 25%), and is often used in various radio frequency terminal equipment.
  • the filter 10 composed of a cascade of series-parallel lamb wave resonators 100 with different resonant frequencies has the advantages of small passband insertion loss, high out-of-band steepness, and strong power tolerance.
  • FIG. 3A a lamb wave resonator 100 is illustrated, including a piezoelectric layer 110, an interdigital transducer 120 and a frequency shifting layer.
  • FIG. 3B is an admittance curve diagram of the lamb wave resonator 100 shown in FIG. 3A.
  • A1 first-order antisymmetric
  • A3 modal transverse third harmonic
  • A0 zeroth-order antisymmetric
  • S0 zeroth-order symmetric
  • the transverse mode is caused by the leakage of acoustic wave energy in the aperture direction of the electrode fingers (the extension direction of the electrode fingers in the interdigital transducer 120, or understood as the direction perpendicular to the current cross-section from the perspective of FIG. 3A), beyond the resonant cavity.
  • the sound waves (the electrode finger ends define the range of the resonant cavity) are called sound wave leakage.
  • the leakage of sound waves along the aperture direction will cause the positive and negative harmonics of the A1 mode in the admittance diagram.
  • a series of small resonance peaks are formed between the vibration peaks, as shown in the dotted box in Figure 3B, which will cause fluctuations in the passband of the lamb wave resonator 100.
  • the A1 mode will generate higher harmonics in the transverse direction.
  • the closest harmonic to the A1 mode is the A1-3 harmonic.
  • the location of this harmonic corresponds to the interval of the passband and often falls in the lamb wave resonance. within the passband of the lamb wave resonator 100, causing fluctuations within the passband of the lamb wave resonator 100.
  • S0 mode transverse harmonics are a type of plate wave. Between the forward and reverse resonance peaks of A1 mode, S0 mode transverse harmonics will also appear, as shown in Figure 3B. This type of miscellaneous mode is S0 Modal transverse high-order harmonics and S0 mode transverse high-order harmonics will also cause fluctuations in the lamb wave resonator 100 band and increase losses. It should be understood that waves propagating in the piezoelectric layer are generally called plate waves, and waves propagating on the surface of the piezoelectric layer are generally called surface waves.
  • the S0 mode transverse high-order harmonics may appear, and the A0 mode transverse high-order harmonics may also appear.
  • the A0 mode transverse high-order harmonics are also a type of plate wave. Will appear between the forward and reverse resonance peaks of the A1 mode.
  • the A0 mode transverse high-order harmonics will also cause fluctuations in the lamb wave resonator 100 band and increase the loss.
  • the A0 mode transverse high-order harmonics and the S0 mode transverse high-order harmonics may also appear at the same time, which will also cause fluctuations in the lamb wave resonator 100 band and increase the loss.
  • miscellaneous modes will cause fluctuations in the passband of the lamb wave resonator, increase the in-band loss, and reduce the performance of the lamb wave resonator.
  • a conventional lamb wave resonator 100 includes a piezoelectric layer 110 and an interdigital transducer 120 disposed on the surface of the piezoelectric layer 110 . Due to the coverage of the electrode fingers, the structure of the area covered by the electrode fingers and the area not covered by the piezoelectric layer 110 will be different, resulting in acoustic impedance mismatch (or understood as unequal acoustic impedance), dispersion curve (resonance) The curve generated by the change of frequency with wavelength) also produces a mismatch, which in turn causes the sound wave to reflect, causing spurious modes.
  • a lamb wave resonator 100 including a piezoelectric layer 110 and an interdigital transducer 120.
  • the surface of the piezoelectric layer 110 has grooves, and the interdigital transducer 120 has a plurality of electrode fingers.
  • the electrode fingers of the finger transducer 120 are disposed in the grooves.
  • FIG. 4C is an admittance curve diagram of the lamb wave resonator 100 shown in FIG. 4A
  • FIG. 4D is an admittance curve diagram of the lamb wave resonator 100 shown in FIG. 4B . Comparing Figure 4C and Figure 4D, it can be seen that by etching the piezoelectric layer 110 in the area covering the electrode fingers to a certain depth, and then depositing the electrode fingers, the acoustic impedances in the areas covered by the electrode fingers and the areas not covered by the electrode fingers are adjusted to be basically the same. , which can suppress A1-3 harmonics.
  • the preparation process for forming grooves on the piezoelectric layer 110 is relatively complicated. , The process is difficult.
  • the suppression principle of the recessed electrode finger structure is to form grooves by thinning the piezoelectric layer 110 to reduce the acoustic resistance in the area where the grooves are located. Setting electrode fingers in the groove can improve the acoustic resistance in the area where the groove is located.
  • the combination of the reduced acoustic resistance and the increased acoustic resistance causes the acoustic impedance in the area where the groove is located to match (or be understood to be equal) to the acoustic impedance at other positions of the piezoelectric layer 110 (where electrode fingers are not provided), thereby achieving suppression.
  • the effect of A1-3 harmonics. Therefore, the suppression effect of the A1-3 harmonic is closely related to the concave depth of the piezoelectric layer 110 and the thickness of the electrode fingers. It is necessary to accurately control the concave depth of the piezoelectric layer 110 and the thickness of the electrode fingers, and the process tolerance is small.
  • the lamb wave resonator 100 shown in FIG. 4B is mainly used to suppress the A1-3 harmonic during structural design.
  • the lamb wave resonator 100 includes: a substrate 140, a piezoelectric layer 110, an interdigital transducer 120, and a dielectric layer 130.
  • the material of the substrate 110 may be, for example, lithium niobate (LiNbO3, LN), lithium tantalate (LiTaO3, LT), quartz (quartz), silicon (Si), ceramics (ceramics), or glass (glass).
  • the main components of ceramics include, for example, silicates and aluminosilicates, refractory metal oxides, metal nitrides, borides, etc.
  • the main components of glass include, for example, hexasilica, calcium oxide, and sodium oxide (Na2O ⁇ CaO ⁇ 6SiO2).
  • the structure of the substrate 140 is also different depending on the type of the lamb wave resonator 100, and any substrate structure in the related art is applicable to this application.
  • the lamb wave resonator 100 has a back-etching structure.
  • the substrate 140 is in The middle area has an opening, and the opening exposes the piezoelectric layer 110 .
  • a back etching process may be used to form an opening on the substrate 140 so that the piezoelectric layer 110 in the middle region is suspended and the lower surface of the piezoelectric layer 110 in the middle region is in contact with the air.
  • the acoustic impedance of air is relatively low and can reflect sound waves back to the piezoelectric layer 110 , thereby limiting the sound wave energy in the piezoelectric layer 110 .
  • the lamb wave resonator 100 is an air gap structure.
  • the substrate 140 has a groove 141 in the middle region on the side facing the piezoelectric layer 110 .
  • an etching process is used to etch the release window 111 on the piezoelectric layer 110, and then the groove 141 is formed in the middle area of the substrate 140 through the release process, so that the piezoelectric layer 110 in the middle area is suspended, and the piezoelectric layer 110 in the middle area is suspended.
  • the lower surface of the piezoelectric layer 110 is in contact with air.
  • the acoustic impedance of air is relatively low and can reflect sound waves back to the piezoelectric layer 110 , thereby confining the sound waves in the piezoelectric layer 110 .
  • the lamb wave resonator 100 is a solid-state assembly structure.
  • the surface of the substrate 140 is flat.
  • the lamb wave resonator 100 also includes a Bragg reflector disposed below the piezoelectric layer 110.
  • the Bragg reflector includes alternating high acoustic impedance layers and low acoustic impedance layers.
  • the material of the low acoustic impedance layer may be, for example, zinc oxide, silicon dioxide, etc.
  • the material of the high acoustic impedance layer may be, for example, heavy metal. Heavy metals refer to metals with a density greater than 4.5g/cm3, including gold, silver, copper, iron, mercury, lead, cadmium, etc.
  • the low-acoustic impedance layer is a film layer with slightly lower acoustic impedance than the high-acoustic impedance layer.
  • the acoustic impedance of both the low-acoustic impedance layer and the high acoustic impedance layer may be greater than the piezoelectric layer.
  • the Bragg reflective structure can confine the sound waves in the piezoelectric layer 110, thereby confining the sound waves in the piezoelectric layer 110.
  • the lamb wave resonator 100 is a single-layer reflective layer structure.
  • the surface of the substrate 140 is flat.
  • the lamb wave resonator 100 also includes an acoustic wave reflection layer disposed below the piezoelectric layer 110.
  • the acoustic impedance of the piezoelectric layer 110 is greater than the acoustic impedance of the acoustic wave reflection layer, so that The sound wave is reflected on the surface of the sound wave reflection layer facing the piezoelectric layer 110 and reflected back to the piezoelectric layer 110 .
  • the acoustic impedance of the acoustic wave reflection layer only needs to be smaller than the acoustic impedance of the piezoelectric layer 110 , and the relationship between the acoustic impedance between the acoustic wave reflection layer and the substrate 140 is not limited.
  • the acoustic impedance of the acoustic wave reflective layer may be smaller than the acoustic impedance of the substrate 140 , the acoustic impedance of the acoustic wave reflective layer may also be greater than the acoustic impedance of the substrate 140 , and the acoustic impedance of the acoustic wave reflective layer may also be equal to the acoustic impedance of the substrate 140 .
  • Acoustic impedance is a mechanical term that refers to the complex ratio of the pressure of the medium on a certain area of the wave front to the volume velocity passing through this area.
  • the unit of acoustic impedance is Pascal ⁇ per square meter ⁇ second (Pa ⁇ m - 2 s -1 ).
  • v 120 and v 110 are the Z-direction shear wave speed in the acoustic wave reflection layer and the piezoelectric layer 110
  • ⁇ 120 and ⁇ 110 are the densities of the acoustic wave reflection layer and the piezoelectric layer 110
  • C 44 is the elasticity of the piezoelectric layer 110 Stiffness coefficient
  • E is the Young's modulus of the sound wave reflection layer
  • the units of Young's modulus are Pa
  • ⁇ is the Poisson's ratio of the sound wave reflection layer.
  • the sound wave reflection coefficient R can be calculated by the following formula:
  • the sound wave reflection coefficient R is related to the limiting effect of sound waves.
  • the value range of the acoustic wave reflection coefficient R is 0.5 ⁇ R ⁇ 0.86.
  • the values of the sound wave reflection coefficient R are 0.6, 0.65, 0.7, 0.75, 0.8, and 0.85.
  • the sound wave reflection coefficient R By limiting the sound wave reflection coefficient R to be greater than or equal to 0.5, the sound wave can be more effectively limited in the piezoelectric layer 110, making the performance of the lamb wave resonator 100 provided by the embodiment of the present application comparable to that of the air gap type lamb wave resonator. Performance is similar.
  • the sound wave reflection coefficient R is too small (less than 0.5), the sound wave will not be well confined in the piezoelectric layer 110, or the sound wave reflection layer used to limit the sound wave needs to be very thick, which is difficult to implement in engineering. The problem. It can also be improved because the sound wave reflection coefficient R is too large (greater than 0.86), resulting in relatively small parameters such as density and Young's modulus of the sound wave reflection layer material, and the material is relatively soft.
  • the processing of the lamb wave resonator 100 such as annealing after bonding the piezoelectric layer
  • the acoustic wave reflective layer is easily deformed, causing the piezoelectric layer 110 above it to wrinkle or crack, affecting product yield.
  • the material of the sound wave reflection layer can be any material that satisfies the sound wave reflection coefficient R.
  • the material of the sound wave reflection layer is a macromolecular material.
  • Polymer materials also known as polymer materials, are materials composed of polymer compounds as a matrix and other additives (auxiliaries).
  • Examples of materials for the sound reflection layer include polyimide (PI), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polyvinylidene fluoride ( polyvinylidene fluoride (PVDF) or polyethylene glycol terephthalate (polyethylene glycol terephthalate, PET), etc.
  • PI polyimide
  • PDMS polydimethylsiloxane
  • PMMA polymethyl methacrylate
  • PVDF polyvinylidene fluoride
  • PET polyethylene glycol terephthalate
  • spin coating magnetron sputtering, physical vapor deposition, chemical vapor deposition, epitaxial growth and other processes can be used to form the acoustic wave reflection layer.
  • the process is simple, the cost is low and the yield is high.
  • the acoustic reflective layer is a single film layer.
  • the sound wave reflection layer 120 is a single film layer and is not a structure formed by laminating multiple film layers.
  • the acoustic impedance difference between the acoustic wave reflection layer and the piezoelectric layer 110 causes the acoustic wave to be reflected from the acoustic wave reflection layer toward the surface of the piezoelectric layer 110 . Therefore, the sound wave reflection layer only needs to be a single film layer, and the structure is simple and the preparation process is simple.
  • the sound wave reflection layer 120 may also include multiple film layers, and is a structure composed of multiple film layers laminated.
  • the embodiment of the present application does not limit the specific structure of the sound wave reflection layer 120, nor does it limit the relationship between the acoustic impedances between the multi-layer film layers. Sound waves can be reflected on the surface of the sound wave reflection layer 120 toward the piezoelectric layer 130. That is, Can.
  • the sound wave reflection coefficient R of the sound wave reflection layer is different, and the minimum thickness of the sound wave reflection layer is also different.
  • the thickness of the acoustic reflective layer ranges from 3.5 ⁇ m to 30 ⁇ m.
  • the thickness of the sound wave reflection layer is 10 ⁇ m, 15 ⁇ m, 20 ⁇ m or 25 ⁇ m.
  • the surface of the piezoelectric layer 110 facing the interdigital transducer 120 is flat, and there is no need to form a surface on the surface of the piezoelectric layer 110 for A groove in which the interdigital transducer 120 is placed.
  • the material of the piezoelectric layer 110 includes piezoelectric materials such as lithium niobate (LiNbO 3 , LN), lithium tantalate (LiTaO 3 , LT), aluminum nitride (AlN), zinc oxide (ZnO), or quartz. one or more of the materials.
  • the material of the piezoelectric layer 130 The material can be lithium niobate in various tangential directions.
  • the material of the piezoelectric layer 110 is LiNbO 3 , and its tangential direction is the Z tangential direction.
  • the Z-tangential LiNbO 3 piezoelectric material can increase the bandwidth of the lamb wave resonator 100.
  • the material of the piezoelectric layer 110 is LiNbO 3 , and its Euler angle ranges from (0, 20, 0) to (0, 40, 0).
  • the material of the piezoelectric layer 110 is LiNbO 3 , and its Euler angles are (0, 25, 0), (0, 30, 0), and (0, 35, 0).
  • the three numbers ( ⁇ , ⁇ , ⁇ ) in the Euler angle respectively represent that the single crystal pulled out first rotates ⁇ around the z-axis, then rotates ⁇ around the x-axis, and finally rotates ⁇ around the z-axis. This determines the tangential direction of the crystal. Therefore, once the Euler angle is determined, the tangential direction of the crystal is determined.
  • the resonance characteristics of the lamb wave resonator 100 can be improved.
  • the thickness of piezoelectric layer 110 is 0.2 ⁇ m-1 ⁇ m.
  • the thickness of the piezoelectric layer 110 is 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m, 0.6 ⁇ m, 0.7 ⁇ m, 0.8 ⁇ m, and 0.9 ⁇ m.
  • the thickness of the piezoelectric layer 110 is directly related to the frequency of the lamb wave resonator. The thinner the piezoelectric layer, the higher the frequency of the device. This application limits the thickness of the piezoelectric layer to 0.2 ⁇ m-1 ⁇ m, allowing the lamb wave resonator to be used in high frequencies.
  • the interdigital transducer 120 is disposed on a side of the piezoelectric layer 110 away from the substrate 140 .
  • the interdigital transducer 120 is disposed on a surface of the piezoelectric layer 110 away from the substrate 140 .
  • the interdigital transducer 120 can be understood as forming a metal pattern shaped like intersecting fingers of two hands on the surface of the piezoelectric layer 110, and its function is to realize acoustic-electrical transduction.
  • the above-mentioned interdigital transducer 120 includes a first busbar 121a and a second busbar 122a arranged oppositely, and a plurality of first electrode fingers (interdigitated transducer, IDT). ) 121b, and a plurality of second electrode fingers 122b.
  • the extending direction of the first bus bar 121a and the second bus bar 122a is parallel to the first direction X
  • the extending direction of the first electrode finger 121b is parallel to the second direction Y
  • the first electrode finger 121b extends from the first bus bar 121a to the second
  • the bus bar 122a protrudes, and the plurality of first electrode fingers 121b are coupled with the first bus bar 121a.
  • the extending direction of the second electrode fingers 122b is parallel to the second direction Y.
  • the second electrode fingers 122b protrude from the second bus bar 122a toward the first bus bar 121a.
  • the plurality of second electrode fingers 122b are coupled to the second bus bar 122a.
  • the first direction X intersects the second direction Y.
  • parallel in the embodiment of the present application includes approximately parallel, and deviations within the range of process errors (for example, ⁇ 5°) belong to parallel in the embodiment of the present application.
  • a plurality of first electrode fingers 121b and a plurality of second electrode fingers 122b are alternately arranged along the first direction X between the first bus bar 121a and the second bus bar 122a. There is no contact between the electrode fingers 122b.
  • the plurality of first electrode fingers 121b and the plurality of second electrode fingers 122b are alternately arranged along the first direction X between the first bus bar 121a and the second bus bar 122a" refers to: on the first bus bar Between 141a and the second bus bar 142a, a second electrode finger 142b is disposed between every two first electrode fingers 141b, and a first electrode finger 141b is disposed between every two second electrode fingers 142b.
  • the number of first electrode fingers 121b and the number of second electrode fingers 122b in the interdigital transducer 120 are not limited and can be set as needed.
  • the plurality of first electrode fingers 121b may be arranged at equal intervals or may be arranged at non-equal intervals.
  • the plurality of second electrode fingers 122b may be arranged at equal intervals or at non-equally spaced intervals.
  • the non-equally spaced arrangement of the plurality of first electrode fingers 121b refers to the distance between at least one pair of adjacent first electrode fingers 121b and the distance between another pair of adjacent first electrode fingers. The spacing between 121b is not the same.
  • the plurality of first electrode fingers 121b and the plurality of second electrode fingers 122b are arranged alternately in sequence.
  • the spacing between adjacent first electrode fingers 121b and the second electrode fingers 122b may be the same; or there may be multiple pairs of opposite electrode fingers 121b and second electrode fingers 122b.
  • the spacing between adjacent first electrode fingers 121b and second electrode fingers 122b is not exactly the same, that is, the spacing between at least one pair of adjacent first electrode fingers 121b and second electrode fingers 122b is different from another pair of adjacent first electrode fingers 121b and second electrode fingers 122b.
  • the spacing between the first electrode finger 121b and the second electrode finger 122b is different.
  • the spacing between adjacent first electrode fingers 121b and second electrode fingers 122b is 2 ⁇ m-10 ⁇ m.
  • first electrode fingers 121b and second electrode fingers 122b are -4 ⁇ m, 4 ⁇ m-5 ⁇ m, 5 ⁇ m-6 ⁇ m, 6 ⁇ m-7 ⁇ m, 7 ⁇ m-8 ⁇ m, 8 ⁇ m-9 ⁇ m, or 9 ⁇ m-10 ⁇ m.
  • the spacing between the first electrode finger 141b and the second electrode finger 142b directly affects the frequency of the lamb wave resonator 100, At the same time, the bandwidth of the lamb wave resonator 100 is also affected. Generally speaking, the greater the spacing, the greater the bandwidth. Therefore, by limiting the spacing between adjacent first electrode fingers 141b and second electrode fingers 142b to 2 ⁇ m-10 ⁇ m, the lamb wave resonator 100 can be made to work in the fifth generation mobile communication technology (5G). ) frequency band, with a wider bandwidth.
  • 5G fifth generation mobile communication technology
  • the width of the first electrode finger 141b is 200 nm-1000 nm
  • the width of the second electrode finger 142b is 200 nm-1000 nm.
  • the width of the first electrode finger 141b and the second electrode finger 142b is between 200nm-300nm, between 300nm-400nm, between 400nm-500nm, between 500nm-600nm, between 600nm-700nm, and 700nm-800nm. between, between 800nm-900nm or between 900nm-1000nm.
  • the duty cycle mainly affects the bandwidth of the lamb wave resonator 100, it also affects the frequency of the lamb wave resonator 100.
  • the duty cycle the width of the electrode fingers/(the width of the electrode fingers + the spacing between the electrode fingers), when the spacing between the electrode fingers is determined, adjusting the width of the electrode fingers can adjust the lamb wave resonator 100 bandwidth and frequency. Therefore, by limiting the width of the adjacent first electrode finger 141b and the second electrode finger 142b to 200 nm-1000 nm, the lamb wave resonator 100 can be made to operate in the 5G frequency band and have a wider bandwidth.
  • the pitch between the first electrode finger 121b and the second electrode finger 122b and the width of the first electrode finger 121b and the second electrode finger 122b are mainly affected by the photolithography and development processes.
  • the resonant frequency and bandwidth of the lamb wave resonator 100 can be changed, so that a specific Electronic signals with frequencies can pass through the lamb wave resonator 100 , while electronic signals with other frequencies will be filtered out by the lamb wave resonator 100 .
  • first bus bar 121a, the first electrode finger 121b, the second bus bar 122a and the second electrode finger 122b can be manufactured at the same time. You may also make the first bus bar 121a and the first electrode finger 121b first, and then make the second bus bar 122a and the second electrode finger 122b. Alternatively, the second bus bar 122a and the second electrode finger 122b are formed first, and then the first bus bar 121a and the first electrode finger 121b are formed.
  • the materials of the first electrode finger 121b and the second electrode finger 122b may include aluminum (Al), copper (Cu), platinum (Pt), gold (Au), nickel (Ni), titanium (Ti), and Ag (silver). , chromium (Cr), molybdenum (Mo), tungsten (W), tantalum (Ta), etc. One or more.
  • the side surfaces where the first electrode finger 121 b and the second electrode finger 122 b intersect with the piezoelectric layer 110 are perpendicular to the piezoelectric layer 110 .
  • the side surfaces of the first electrode finger 121b and the second electrode finger 122b may also have a certain tilt angle with the piezoelectric layer 110.
  • the angle ⁇ between the side surfaces of the first electrode finger 121b and the second electrode finger 122b and the piezoelectric layer 110 is 70°. ⁇ 90°.
  • the first electrode finger 121 b and the second electrode finger 122 b of the interdigital transducer 120 are illustrated in the cross-sectional views of FIGS. 5A to 5D .
  • the first direction X is the arrangement direction of the first electrode finger 121b and the second electrode finger 122b
  • the second direction Y is the extension direction of the first electrode finger 121b and the second electrode finger 122b
  • the third direction Z is the thickness direction of the lamb wave resonator 100 .
  • the first direction X intersects the second direction Y
  • the third direction Z is perpendicular to the plane where the first direction X and the second direction Y lie.
  • the air gap type lamb wave resonator 100 is taken as an example to schematically illustrate the structure of the dielectric layer 130 .
  • the dielectric layer 130 and the interdigital transducer 120 are located on the same side of the piezoelectric layer 110.
  • the dielectric layer 130 includes a first part 131 and a second part 132.
  • the first portion 131 is disposed on the surface of the piezoelectric layer 110 and is located at the periphery of the first electrode finger 121b and the second electrode finger 122b.
  • the second portion 132 is located on the top surface of the interdigital transducer 120 (the surface remote from the piezoelectric layer 110).
  • the dielectric layer 130 is formed on the surface of the interdigital transducer 120, and a part of the dielectric layer 130, as the first part 131 in the embodiment of the present application, falls into the gap of the interdigital transducer 120 and interacts with the piezoelectric transducer 120. Layer 110 is in direct contact. Another part of the dielectric layer 130 as the second part 132 in the embodiment of the present application falls on the surface of the interdigital transducer 120 and contacts the interdigital transducer 120 .
  • the part in contact with the piezoelectric layer 110 is the first part 131, and the part in contact with the interdigital transducer 120 is the second part 132.
  • the second portion 132 has a first projection on the surface of the piezoelectric layer 110
  • the interdigital transducer 120 has a second projection on the surface of the piezoelectric layer 110
  • the second projection includes the first projection.
  • the second part 132 is disposed on the top surface of the interdigital transducer 120 .
  • the first projection coincides with the second projection.
  • the second projection of the example overlays the first projection.
  • the shape of the second part 133 in the dielectric layer 130 basically coincides with the shape of the interdigital transducer 120 , and structures other than the second part 133 belong to the first part 131 .
  • the interface between the first part 131 and the second part 132 should Corresponds to the boundary between the top surfaces of the first electrode finger 121b and the second electrode finger 122b. That is, the boundary of the second portion 132 corresponds to the boundary of the top surfaces of the first electrode finger 121b and the second electrode finger 122b.
  • the process error shift may be, for example, the left and right shift of the interface by 150 nm at the viewing angle in FIG. 6B .
  • the thickness of the first part 131 is S1 and the thickness of the second part 132 is S2, S1>S2.
  • Finite element simulation is performed on the lamb wave resonator 100 provided by the embodiment of the present application and the lamb wave resonator 100 provided by related technologies, and the obtained admittance curve is shown in Figure 8A.
  • the solid line is the lamb wave resonator 100 provided in the embodiment of the present application.
  • the admittance curve of the lamb wave resonator 100 (S1>S2) provided in the embodiment of this application that the A0 mode transverse high-order harmonics and the S0 mode transverse high-order harmonics between the forward and anti-resonance peaks of the A1 mode The harmonics are well suppressed, and the spurious mode to the left of the positive resonance peak of the A1 mode is also well suppressed, or even completely suppressed.
  • the admittance curve of the lamb wave resonator 100 is smooth and the performance is good.
  • the lamb wave resonator 100 provided by the embodiment of the present application can suppress the A0 mode in the lamb wave resonator 100 by thinning the thickness S2 of the second portion 132 of the dielectric layer 130 located above the interdigital transducer 120
  • the effects of plate wave dispersion modes such as transverse high-order harmonics and S0 mode transverse high-order harmonics improve the flatness within the passband, reduce losses, and improve the performance of the lamb wave resonator 100.
  • the lamb wave resonator 100 provided by the embodiment of the present application thins the thickness S2 of the second portion 132 of the dielectric layer 130 above the interdigital transducer 120, which is equivalent to processing the dielectric layer 130.
  • the material of the dielectric layer 130 is a dielectric material.
  • the process of etching dielectric materials is relatively mature.
  • the dielectric layer 130 of the present application is prepared. The processes used can all adopt relatively mature processes in related technologies.
  • the material of the piezoelectric layer 110 is a piezoelectric material.
  • the lamb wave resonator 100 provided by the embodiment of the present application has a simple manufacturing process, low process difficulty, low manufacturing cost, and can improve the yield of the lamb wave resonator 100 .
  • FIG. 8B illustrates the admittance curve of the lamb wave resonator 100 provided by the embodiment of the present application and the admittance curve of the lamb wave resonator 100 shown in FIG. 4B.
  • the provided lamb wave resonator 100 has a better suppression effect on plate wave dispersion modes such as A0 mode transverse high-order harmonics and S0 mode transverse high-order harmonics.
  • the lamb wave resonator 100 includes a frequency shifting layer, and the frequency shifting layer is used to adjust the frequency of the lamb wave resonator 100 .
  • the frequency shifting layer is disposed on the side of the interdigital transducer 120 away from the piezoelectric layer 110 .
  • the material of the frequency shifting layer may be, for example, silicon nitride (SiN), aluminum oxide (Al 2 O 3 ) or silicon oxide (SiO 2 ).
  • the frequency shifting layer can be directly used as the dielectric layer 130 in the lamb wave resonator 100 provided in the embodiment of the present application, and the frequency shifting layer can be processed without adding a new film layer, and the changes to the lamb wave resonator 100 are relatively small.
  • the lamb wave resonator 100 provided with a frequency shifting layer may be applied to n77 frequency band (3.3GHz-4.2GHz), n78 frequency band (3.3GHz-3.8GHz), n79 In the 5th generation mobile communication technology (5G) frequency band (4.4GHz-5.0GHz) and other frequency bands, the operating frequency is 450MHz Filters for frequency bands below 6G (sub-6G frequency band) to 6000MHz.
  • a frequency shifting layer eg, a thinned frequency shifting layer
  • the dielectric layer 130 includes a first part 131, which is disposed on the surface of the piezoelectric layer 110 and located at the periphery of the first electrode finger 121b and the second electrode finger 122b.
  • the second portion 132 located above the interdigital transducer 120 is not included in the dielectric layer 130 .
  • the structure of the dielectric layer 130 (first part 131 ) is as shown in FIG. 9B .
  • the dielectric layer 130 has a hollow pattern.
  • the top view of the hollow pattern basically coincides with the top view of the interdigital transducer 120 .
  • the dielectric layer 130 includes a first part 131 and a second part 132.
  • the first part 131 is provided on the surface of the piezoelectric layer 110 and is located at the periphery of the first electrode finger 121b and the second electrode finger 122b.
  • the second portion 132 is located on the top surface of the IDT 120 .
  • the S1 and S2 combination corresponding to number 1 in Table 1 means that under the corresponding S1 and S2 values, the A0 mode transverse high-order harmonics and the S0 mode transverse high-order harmonics are better suppressed (can be understood as , for example, the peak-to-peak value of the A0 mode transverse harmonics and the S0 mode transverse harmonics is less than 5dB).
  • the S1 and S2 combination corresponding to number 2 in Table 1 means that under the corresponding S1 core S2 value, the A0 mode transverse high-order harmonics and the S0 mode transverse high-order harmonics are almost completely suppressed (can be understood as, For example, the peak-to-peak values of the transverse harmonics of the A0 mode and the transverse harmonics of the S0 mode are less than 2.5dB).
  • the A0 mode transverse harmonic and the S0 mode transverse harmonic are Almost completely suppressed.
  • the thickness S1 of the first part 131 has a value of 115 nm and the thickness S2 of the second part 132 has a value of 55 nm, the suppression effect of the A0 mode transverse harmonics and the S0 mode transverse harmonics is relatively small. good.
  • the difference between S1 and S2 has a certain impact on the suppression effect of the transverse harmonics of the A0 mode and the transverse harmonics of the S0 mode.
  • the suppression of the A0 mode transverse harmonics and the S0 mode transverse harmonics can be better achieved.
  • the thickness S1 of the first part 131 is fixed at 115 nm
  • the thickness S2 of the second part 132 is set in the range of 5 nm to 85 nm
  • the admittance curves of the lamb wave resonator 100 under different S2 are simulated through finite element simulation.
  • the thickness S1 of the first part 131 when the thickness S1 of the first part 131 is fixed, the thickness S2 of the second part 132 can have a large variation range. Within this large range, the transverse high-order control of the A0 mode can be achieved. Suppression of harmonics and S0 mode transverse higher harmonics. It is not fixed to a certain value or a smaller range to achieve the suppression of A0 mode transverse high-order harmonics and S0 mode transverse high-order harmonics.
  • the value of the thickness S1 of the first part 131 can also be within a larger range. Within this larger range, the A0 mode transverse higher harmonics and the S0 mode can be realized. Suppression of transverse harmonics. It is not fixed to a certain value or a smaller range to achieve the suppression of A0 mode transverse high-order harmonics and S0 mode transverse high-order harmonics.
  • the thickness S1 of the first part 131 of the dielectric layer 130 in the lamb wave resonator 100 provided by the embodiment of the present application has a relatively large value range
  • the thickness S2 of the second part 132 of the dielectric layer 130 also has a relatively large value range.
  • a large value range, and S1-S2 also has a large value range. Therefore, the thickness of the dielectric layer 130 in the lamb wave resonator 100 provided by the embodiment of the present application has a wide value range, and the lamb wave resonator 100 has a large tolerance range for process errors.
  • the thickness S1 of the first part 131 of the dielectric layer 130 has a value of 30nm-50nm, 50nm-70nm, 70nm-90nm, 90nm-100nm, 100nm-120nm, 120nm-140nm, 140nm-145nm, 145nm-150nm, 150nm- 155nm, 155nm-160nm, 160nm-165nm, 165nm-170nm, 170nm-175nm, 175nm-180nm, 180nm-185nm, 185nm-190nm, 190nm-195nm, 195nm-200nm.
  • the thickness S1 of the first part 131 of the dielectric layer 130 By limiting the value of the thickness S1 of the first part 131 of the dielectric layer 130 to 20nm-200nm, it is possible to suppress the A0 mode transverse harmonics and the S0 mode transverse harmonics without excessively increasing the lamb.
  • the thickness of the wave resonator 100 By limiting the value of the thickness S1 of the first part 131 of the dielectric layer 130 to 20nm-200nm, it is possible to suppress the A0 mode transverse harmonics and the S0 mode transverse harmonics without excessively increasing the lamb.
  • the thickness of the wave resonator 100 By limiting the value of the thickness S1 of the first part 131 of the dielectric layer 130 to 20nm-200nm, it is possible to suppress the A0 mode transverse harmonics and the S0 mode transverse harmonics without excessively increasing the lamb.
  • the thickness of the wave resonator 100 By limiting the value of the thickness S1 of the first part 131 of the dielectric layer 130
  • S1-S2 By limiting the value of S1-S2 to greater than 65nm, and limiting the value of S1 to 110nm-140nm, it is almost possible to completely suppress the A0 mode lateral high-order harmonics and the S0 mode lateral high-order harmonics, and the lamb wave The performance of the resonator 100 is better.
  • the thickness of the interdigital transducer 120 ranges from 60 nm to 140 nm.
  • the thickness of the interdigital transducer 120 has a value of 70nm-75nm, 75nm-80nm, 80nm-85nm, 85nm-90nm, 90nm-95nm, 95nm-100nm, 100nm-105nm, 105nm-110nm, 110nm-115nm. , 115nm-120nm, 120nm-125nm, 125nm-130nm, 130nm-135nm, 135nm-140nm.
  • the material of the interdigital transducer 120 is aluminum.
  • the thickness S3 of the interdigital transducer 120 is set in the range of 20nm-160nm, and different values are simulated through finite element simulation.
  • the thickness of the interdigital transducer 120 corresponds to the admittance curve of the lamb wave resonator 100 .
  • 11A to 11C illustrate the admittance curve of the lamb wave resonator 100 when the thickness S3 of the interdigital transducer 120 is 60 nm, 100 nm, and 140 nm.
  • the thickness range of the interdigital transducer 120 in the lamb wave resonator 100 provided by the embodiment of the present application is relatively wide, and the lamb wave resonator 100 can be suitable for scenarios that require different thicknesses of the interdigital transducer 120 ,Wide range of applications.
  • the thickness S1 of the first part 131 of the dielectric layer 130 in the lamb wave resonator 100 provided by the embodiment of the present application has a wide value range, and the difference between the thickness S1 of the first part 131 of the dielectric layer 130 and the thickness S2 of the second part is The value range is wide, and the value range of the interdigital transducer 120 is also relatively wide.
  • the dielectric layer 130 will appear to be flush with the top surface a1 of the first part 131 and the top surface a2 of the second part 132 as shown in FIG. 9C .
  • the top surface a1 of the first part 131 can be understood as the surface of the first part 131 away from the piezoelectric layer 110 .
  • the top surface a2 of the second part 132 can be understood as the surface of the second part 132 away from the piezoelectric layer 110 .
  • the top surface a1 of the first part 131 is flush with the top surface a2 of the second part 132. It can be understood that the distance from the top surface a1 of the first part 131 to the piezoelectric layer 110 is the same as the distance from the top surface a2 of the second part 132 to the piezoelectric layer. 110 is the same distance.
  • the dielectric layer 130 may also have a situation where the top surface a1 of the first part 131 is lower than the top surface a2 of the second part 132 .
  • the top surface a1 of the first part 131 is lower than the top surface a2 of the second part 132 . It can be understood that the distance from the top surface a1 of the first part 131 to the piezoelectric layer 110 is shorter than the distance from the top surface a2 of the second part 132 to the piezoelectric layer 110 . electrical layer 110 distance.
  • the dielectric layer 130 may also have a situation where the top surface a1 of the first part 131 is higher than the top surface a2 of the second part 132 as shown in FIG. 7A .
  • the thickness of the first part 131 in the dielectric layer 130 is equal at each position, and the thickness of the second part 132 at each position is equal.
  • the material of the dielectric layer 130 includes silicon nitride (Si 3 N 4 ), aluminum oxide (Al 2 O 3 ), or silicon oxide (SiO 2 ).
  • the embodiment of the present application does not limit the size of the dielectric layer 130.
  • the dielectric layer 130 can be located only in the central area of the piezoelectric layer 110, surrounding the interdigital transducer 120. That is, Can.
  • the dielectric layer 130 may also be located on the areas of the piezoelectric layer 110 on both sides of the release window 111 .
  • the dielectric layer 130 can also be used as a frequency shifting layer of the lamb wave resonator 100 .
  • the material of the dielectric layer 130 may be Si 3 N 4 , Al 2 O 3 or SiO 2 , for example.
  • the lamb wave resonator 100 when the lamb wave resonator 100 includes a frequency shifting layer, there is no need to change the structure of other film layers in the lamb wave resonator 100.
  • the frequency of the lamb wave resonator 100 can be adjusted to the required value. value.
  • the dielectric layer 130 can also be used as a temperature compensation layer of the lamb wave resonator 100 .
  • the material of the dielectric layer 130 may be SiO 2 , for example.
  • the temperature compensation layer can be used to perform temperature compensation on the lamb wave resonator 100, so that the absolute value of the temperature coefficient of frequency (TCF) of the lamb wave resonator 100 is reduced.
  • TCF temperature coefficient of frequency
  • the dielectric layer 130 can also be used as a passivation layer of the lamb wave resonator 100 .
  • the material of the dielectric layer 130 may be Si 3 N 4 , Al 2 O 3 or SiO 2 , for example.
  • the lamb wave resonator 100 when the lamb wave resonator 100 includes a passivation layer, the lamb wave resonator 100 can be processed through the passivation layer. protection, extending the service life of the lamb wave resonator 100.
  • the piezoelectric layer 110 may also be provided with a temperature compensation layer or a frequency shifting layer on the side facing the substrate 140 .
  • the lamb wave resonator 100 includes a dielectric layer 130 and a passivation layer 150 .
  • the passivation layer 150 is disposed on the side of the dielectric layer 130 away from the piezoelectric layer 110 .
  • the thickness of the chemical layer 150 ranges from 1 nm to 50 nm.
  • the material of the passivation layer 150 may be, for example, Si 3 N 4 , Al 2 O 3 or SiO 2 .
  • the film layer between the passivation layer 150 and the substrate 140 can be protected, thereby extending the service life of the lamb wave resonator 100.
  • a method of preparing the lamb wave resonator 100 includes:
  • the structure of the substrate 140 is also different, and the preparation sequence of the substrate 140 and the piezoelectric layer 110 is also different. Reference may be made to the above description of the substrate 140 and its preparation method, which will not be described again here.
  • the piezoelectric layer 110 may be formed using processes such as magnetron sputtering, physical vapor deposition, chemical vapor deposition, epitaxial growth, or bonding between crystals.
  • the embodiments of the present application do not limit the preparation process of the interdigital transducer 120, and the processes used to prepare the interdigital transducer 120 in related technologies are applicable to this application.
  • the dielectric layer 130 includes a first portion 131 disposed on the surface of the piezoelectric layer 110 and located at the periphery of the first electrode finger 121b and the second electrode finger 122b.
  • step S30 includes:
  • the dielectric layer 130 includes a first portion 131 and a second portion 132 .
  • the first part 131 is provided on the surface of the piezoelectric layer 110
  • the second part 132 is provided on the surface of the interdigital transducer 120 .
  • step S30 includes:
  • the above-mentioned dielectric film can be understood as a first dielectric film.
  • the first dielectric film covers the interdigital transducer 120 and the piezoelectric layer 110 .
  • the thickness of the first dielectric film is consistent with the thickness of the second part 132 to be formed. The thicknesses are basically the same.
  • the part of the first dielectric film located on the surface of the piezoelectric layer 110 and the second dielectric film constitute the first part 131 of the dielectric layer 130
  • the part of the first dielectric film located on the top surface of the interdigital transducer 120 serves as the second part of the dielectric layer 130 .
  • the top surface a1 of the first part 131 can be flush with the top surface a2 of the second part 132 .
  • the top surface a1 of the first part 131 is lower than the top surface a2 of the second part 132 .
  • the top surface a1 of the first part 131 is higher than the top surface a2 of the second part 132 .
  • step S30 includes:
  • the above-mentioned dielectric film can be understood as a third dielectric film, and the third dielectric film covers the interdigital transducer 120 and the piezoelectric layer 110 .
  • the thickness of the third dielectric film is also different. The thickness of the third dielectric film will be described below in conjunction with the thinning process.
  • the portion of the third dielectric film located on the surface of the piezoelectric layer 110 is referred to as the first portion 131 , and the thinned portion of the third dielectric film is referred to as the second portion 132 .
  • the entire third dielectric film can be thinned through a chemical mechanical polishing (CMP) process until the thickness of the part of the third dielectric film located on the top surface of the interdigital transducer 120 meets the desired thickness.
  • CMP chemical mechanical polishing
  • the thickness of the third dielectric film should be greater than the thickness of the first portion 131 to be formed.
  • the top surface a1 of the first part 131 of the formed dielectric layer 130 is flush with the top surface a2 of the second part 132 .
  • etching, corrosion, or other processes may be used to selectively thin the portion of the third dielectric film located on the surface of the piezoelectric layer 110 to form the second portion 132 .
  • the thickness of the third dielectric film should be equal to the thickness of the first portion 131 to be formed.
  • the top surface a1 of the first part 131 can be flush with the top surface a2 of the second part 132 .
  • the top surface a1 of the first part 131 is lower than the top surface a2 of the second part 132 .
  • the top surface a1 of the first part 131 is higher than the top surface a2 of the second part 132 .
  • the preparation method of the lamb wave resonator 100 provided by the embodiment of the present application can form the dielectric layer 130 required by the embodiment of the present application by controlling the process of forming the dielectric layer 130, so as to provide a method that can suppress the A0 mode lateral high-order Lamb wave resonator for harmonic and S0 mode transverse higher harmonics.
  • the process for processing dielectric materials is simple, easy to implement, and has a high yield rate.

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Abstract

一种兰姆lamb波谐振器（100）及制备方法、滤波器（10）、射频模组、电子设备（1）。lamb波谐振器（100）作为滤波器（10）的元件，可以应用于射频器件中。lamb波谐振器（100）包括：衬底（140）、压电层（110）、叉指换能器（120）以及介质层（130）。压电层（110）设置在衬底（140）上，叉指换能器（120）和介质层（130）设置在压电层（110）远离衬底（140）一侧。叉指换能器（120）包括多个第一电极指（121b）和多个第二电极指（122b），多个第一电极指（121b）和多个第二电极指（122b）沿第一方向（X）依次交替排布；第一方向（X）与第一电极指（121b）和第二电极指（122b）的延伸方向相交。介质层（130）包括第一部分（131），第一部分（131）设置在压电层（110）的表面，且位于第一电极指（121b）和第二电极指（122b）的外围。

Description

兰姆波谐振器及制备方法、滤波器、射频模组、电子设备
本申请要求于2022年08月27日提交国家知识产权局、申请号为202211036177.8、申请名称为“兰姆波谐振器及制备方法、滤波器、射频模组、电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及射频技术领域，尤其涉及一种兰姆波谐振器及制备方法、滤波器、射频模组、电子设备。
背景技术
随着移动数据的爆炸式增长，通讯行业已经向第五代移动通信技术(5th generation mobile communication technology，5G)迈进，这要求射频前端的谐振器要具有更高的频率、更大的带宽和更强的功率耐受。目前的射频前端谐振器主要有声表面波(surface acoustic wave，SAW)谐振器和体声波(bulk acoustic wave，BAW)谐振器两大类。SAW谐振器的频率低于3.5GHz，且机电耦合系数只有10％左右。BAW谐振器的机电耦合系数也较小。而，兰姆波(lamb wave)谐振器因其具有声速高、机电耦合系数大(高达25％)等优点，成为近年来的研究热点。
因此，如何获得高性能的lamb波谐振器成为当下急需解决的技术问题。
发明内容
本申请实施例提供一种兰姆波谐振器及制备方法、滤波器、射频模组、电子设备，用于提供一种具有高性能的lamb波谐振器。
为达到上述目的，本申请采用如下技术方案：
本申请实施例的第一方面，提供一种兰姆lamb波谐振器，lamb波谐振器作为滤波器的元件，可以应用于射频器件中。lamb波谐振器包括：衬底、压电层、叉指换能器以及介质层。压电层设置在衬底上，叉指换能器和介质层设置在压电层远离衬底的一侧。叉指换能器包括多个第一电极指和多个第二电极指，多个第一电极指和多个第二电极指沿第一方向交替排布；第一方向与第一电极指和第二电极指的延伸方向相交。介质层包括第一部分，第一部分设置在压电层的表面，且位于第一电极指和第二电极指的外围。也就是说，第一部分位于叉指换能器的缝隙处。介质层例如可以同时作为移频层、温度补偿层或者钝化层使用。
本申请实施例提供的lamb波谐振器，通过减薄介质层中位于叉指换能器上方的第二部分的厚度S2，可达到抑制lamb波谐振器中A0模态横向高次谐波和S0模态横向高次谐波等板波杂散模态的效果，提高通带内的平整度，降低损耗，提升lamb波谐振器的性能。而且，本申请实施例提供的lamb波谐振器，是减薄了介质层中位于叉指换能器上方的第二部分的厚度，相当于对介质层进行处理。与相关技术中对压电层进行处理相比，本申请实施例提供的lamb波谐振器的制备工艺简单，工艺难度低，且工艺容差大，可提高lamb波谐振器的良率。另外，通过仿真发现，本申请实施例提供的lamb波谐振器对A0模态横向高次谐波和S0模态横向高次谐波等板波杂散模态的抑制效果比较好。再者，对于应用于n77频带、n78频带、n79频带等5G频段中、工作频率在sub-6G频段的滤波器，lamb波谐振器中通常包括一层材料为介质材料的移频层或者钝化层。因此，可以直接将该移频层或者钝化层作为本申请实施例提供的lamb波谐振器中的介质层，对该移频层或者钝化层进行处理即可，无需新增膜层，对lamb波谐振器的改动较小。
在一些可能的实现方式中，介质层还包括第二部分，第二部分位于叉指换能器的顶面；第一部分的厚度为S1，第二部分的厚度S2，S1>S2。叉指换能器的上方也可以设置厚度较薄的介质层，lamb波谐振器中压电层、插指电极层厚度不同时，可通过减薄第二部分来实现对不同lamb波谐振器中的A0模态横向高次谐波和S0模态横向高次谐波的抑制。
在一些可能的实现方式中，S1-S2≥50nm。通过将第一部分的厚度与第二部分的厚度之差限定在大于50nm，可较好的实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制。
在一些可能的实现方式中，第一部分的厚度为S1，20nm≤S1≤200nm。通过将介质层第一部分的厚度的取值限定在20nm-200nm，既可实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制，又不会过分增加lamb波谐振器的厚度。
在一些可能的实现方式中，S1-S2≥65nm；110nm≤S1≤140nm。通过将第一部分与第二部分的厚度差限定在大于65nm，将第一部分的厚度的取值限定在110nm-140nm，几乎可以实现将A0模态横向高次谐波和S0模态横向高次谐波完全抑制，lamb波谐振器的性能较优。
在一些可能的实现方式中，叉指换能器的厚度的取值范围为60nm-140nm。本申请实施例提供的lamb波谐振器中叉指换能器的厚度取值范围较广，lamb波谐振器可以适用于对叉指换能器有不同厚度需要的场景中，应用范围广。
在一些可能的实现方式中，第一部分与第二部分的顶面平齐。这是一种可能的结构。
在一些可能的实现方式中，第一部分的顶面高于第二部分的顶面。这是一种可能的结构。
在一些可能的实现方式中，第一部分的顶面低于第二部分的顶面。这是一种可能的结构。
在一些可能的实现方式中，第二部分在压电层上具有第一投影，叉指换能器在压电层上具有第二投影，第二投影包含第一投影。第二部分与叉指换能器结构对位设置，对A0模态横向高次谐波和S0模态横向高次谐波的抑制效果较好。
在一些可能的实现方式中，lamb波谐振器还包括钝化层，钝化层设置在介质层远离压电层一侧，钝化层的厚度的取值范围为1nm-50nm。通过设置钝化层，可对钝化层与衬底之间的膜层进行保护，延长lamb波谐振器100的使用寿命。
在一些可能的实现方式中，介质层的材料包括SiO2、Si3N4或者Al2O3。这是一种可能的实现方式。
在一些可能的实现方式中，lamb波谐振器还包括声波反射层，声波反射层设置在压电层远离叉指换能器一侧；声波反射层朝向压电层的表面的声波反射系数为R，0.5≤R≤0.86。
通过在压电层靠近衬底一侧设置声波反射层，且声波反射层的声阻抗小于压电层的声阻抗。这样一来，lamb波谐振器激发出的声波会在声波反射层朝向压电层的表面发生反射，反射回压电层。采用形成在衬底上的单层声波反射层，即可实现将声波锁定在压电层中，避免了lamb波谐振器所激发的声波大量向衬底泄露而导致的器件性能严重退化的问题。声波反射层替代了传统的空气腔和布拉格反射结构，无需掏腔或者形成复杂的布拉格反射结构，简化了lamb波谐振器的制备流程，降低了lamb波谐振器的制备难度。此外，由于无需再衬底上形成空气腔，可增强lamb波谐振器的机械强度，提高lamb波谐振器的良率。
在一些可能的实现方式中，0.55≤R≤0.8。通过将声波反射系数R限定在0.55-0.8，在满足器件性能的基础上，可以同时兼顾声波反射层的选材、厚度设定以及制备工艺等问题，降低制备成本。
在一些可能的实现方式中，声波反射层的最小厚度为y，y＝77.75379*R2-173.22328*R+97.70404。本申请实施例中，声波反射层的选材范围广，每种材料的声波反射层的声波反射系数R不同，每种材料的声波反射层的厚度也不同。本申请通过限定声波反射层的最小厚度，既可以使lamb波谐振器的特性满足需求，又可以便于声波反射层的制备，以兼顾lamb波谐振器的性能、成本、工艺、可靠性等多种特性。
在一些可能的实现方式中，声波反射层的厚度为3.5μm-30μm。这是一种便于量产的厚度范围。
在一种可能的实现方式中，声波反射层的材料为高分子材料。本申请实施例中声波反射层的选材范围广，易于实现。
在一种可能的实现方式中，声波反射层的材料包括聚酰亚胺、聚二甲基硅氧烷、聚甲基丙烯酸甲酯、聚偏氟乙烯或者聚对苯二甲酸乙二醇酯。这是一些成本较低、易于实现的选材。
在一种可能的实现方式中，声波反射层为单膜层结构。单膜层结构的声波反射层结构简单、 工艺简单。
本申请实施例的第二方面，提供一种滤波器，包括多个级联的lamb波谐振器；其中，lamb波谐振器为第一方面任一项的lamb波谐振器。
本申请实施例第二方面提供的滤波器包括第一方面的lamb波谐振器，其有益效果与lamb波谐振器的有益效果相同，此处不再赘述。
本申请实施例的第三方面，提供一种射频模组，包括滤波器和功率放大器，滤波器与功率放大器耦接；滤波器为第二方面的滤波器。
本申请实施例第三方面提供的射频模组包括第一方面的lamb波谐振器，其有益效果与lamb波谐振器的有益效果相同，此处不再赘述。
本申请实施例的第四方面，提供一种电子设备，包括滤波器和电路板，滤波器设置在电路板上；滤波器为第二方面的滤波器。
本申请实施例第四方面提供的电子设备包括第一方面的lamb波谐振器，其有益效果与lamb波谐振器的有益效果相同，此处不再赘述。
本申请实施例的第五方面，提供一种lamb波谐振器的制备方法，包括：形成压电层；在压电层的一侧形成叉指换能器；叉指换能器包括多个第一电极指和多个第二电极指，多个第一电极指和多个第二电极指沿第一方向交替排布；第一方向与第一电极指和第二电极指的延伸方向相交；在压电层的一侧形成介质层，介质层与叉指换能器位于压电层的同一侧；介质层包括第一部分，第一部分设置在压电层的表面，且位于第一电极指和第二电极指的外围。
本申请实施例提供的lamb波谐振器的制备方法，通过控制形成介质层时的工艺，可形成本申请实施例所需的介质层，以提供一种可以抑制A0模态横向高次谐波和S0模态横向高次谐波的lamb波谐振器。对介质材料进行处理，工艺简单，易于实现，良品率高。
在一些可能的实现方式中，介质层还包括第二部分，第二部分位于叉指换能器的顶面；第一部分的厚度大于第二部分的厚度；在压电层一侧形成介质层，包括：形成叉指换能器后，在叉指换能器远离压电层一侧形成第一介质膜；第一介质膜覆盖叉指换能器和压电层；在第一介质膜上形成第二介质膜，第二介质膜位于第一电极指和第二电极指的外围，以形成介质层；第一介质膜位于压电层表面的部分以及第二介质膜构成第一部分，第一介质膜位于叉指换能器顶面的部分作为第二部分。这是一种工艺简单的实现方式。
在一些可能的实现方式中，介质层还包括第二部分，第二部分位于叉指换能器的顶面；第一部分的厚度大于第二部分的厚度；在压电层一侧形成介质层，包括：形成叉指换能器后，在叉指换能器远离压电层一侧形成第三介质膜；第三介质膜覆盖叉指换能器和压电层；对第三介质膜位于叉指换能器顶面的部分进行减薄，以形成介质层；第三介质膜位于压电层表面的部分作为第一部分，第三介质膜减薄后的部分作为第二部分。这是一种工艺简单的实现方式。
在一些可能的实现方式中，第一部分的厚度为S1，第二部分的厚度S2，S1>S2。叉指换能器的上方也可以设置厚度较薄的介质层，lamb波谐振器中压电层、插指电极层厚度不同时，可通过减薄第二部分来实现对不同lamb波谐振器中的A0模态横向高次谐波和S0模态横向高次谐波的抑制。
在一些可能的实现方式中，S1-S2≥50nm。通过将第一部分的厚度与第二部分的厚度之差限定在大于50nm，可较好的实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制。
在一些可能的实现方式中，第二部分在压电层上具有第一投影，叉指换能器在压电层上具有第二投影，第二投影包含第一投影。第二部分与叉指换能器结构对位设置，对A0模态横向高次谐波和S0模态横向高次谐波的抑制效果较好。
附图说明
图1为本申请实施例提供的电子设备的框架示意图；
图2为本申请实施例提供的滤波器的拓扑结构示意图；
图3A为本申请实施例示意的一种lamb波谐振器的部分结构示意图；
图3B为本申请实施例示意的一种图3A所示的lamb波谐振器的三维导纳曲线示意图；
图4A为本申请实施例示意的另一种lamb波谐振器的部分结构示意图；
图4B为本申请实施例示意的又一种lamb波谐振器的部分结构示意图；
图4C为本申请实施例示意的一种图4A所示的lamb波谐振器的二维导纳曲线示意图；
图4D为本申请实施例示意的一种图4B所示的lamb波谐振器的二维导纳曲线示意图；
图5A为本申请实施例提供的一种lamb波谐振器的结构示意图；
图5B为本申请实施例提供的另一种lamb波谐振器的结构示意图；
图5C为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图5D为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图6A为本申请实施例提供的一种叉指换能器的俯视示意图；
图6B为图5D中M处的放大图；
图7A为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图7B为本申请实施例提供的一种介质层的俯视示意图；
图8A为本申请实施例提供的一种导纳曲线对比图；
图8B为本身实施例提供的lamb波谐振器的导纳曲线示意图；
图9A为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图9B为本申请实施例提供的另一种介质层的俯视示意图；
图9C为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图10A-图10C为本申请实施例提供的一种第二部分厚度变化时lamb波谐振器的导纳曲线对比图；
图11A-图11C为本申请实施例提供的一种叉指换能器厚度变化时lamb波谐振器的导纳曲线对比图；
图12为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图13为本申请实施例提供的又一种lamb波谐振器的结构示意图；
图14为本申请实施例提供的一种lamb波谐振器的制备流程示意图；
图15为本申请实施例提供的一种lamb波谐振器的制备步骤示意图。
附图标记：
1-电子设备；11-盖板；12-显示屏；13-中框；131-载板；132-边框；14-后壳；10-滤波器；
100-lamb波谐振器；110-压电层；111-释放窗；120-叉指换能器；121a-第一汇流条；122a-第二汇流条；121b-第一电极指；122b-第二电极指；130-介质层；131-第一部分；132-第二部分；140-衬底；141-凹槽；150-钝化层。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。
以下，术语“第二”、“第一”等仅用于描述方便，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第二”、“第一”等的特征可以明示或者隐含地包括一个或者更多个该特征。在本申请的描述中，除非另有说明，“多个”的含义是两个或两个以上。
此外，本申请实施例中，“上”、“下”、“左”、“右”等方位术语可以包括但不限于相对附图中的部件示意置放的方位来定义的，应当理解到，这些方向性术语可以是相对的概念，它们用于相对于的描述和澄清，其可以根据附图中部件附图所放置的方位的变化而相应地发生变化。
在本申请实施例中，除非另有明确的规定和限定，术语“连接”应做广义理解，例如，“连接”可以是固定连接，也可以是可拆卸连接，或成一体；可以是直接相连，也可以通过中间媒介间接相连。此外，术语“相耦接”可以是直接的电性连接，也可以通过中间媒介间接的电性连接。术语“接触”可以是直接接触，也可以是通过中间媒介间接的接触。
本申请实施例中，“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A，B可以是单 数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。
本申请实施例提供一种的电子设备。该电子设备例如为消费性电子产品、家居式电子产品、车载式电子产品、金融终端产品、通信电子产品。其中，消费性电子产品如为手机(mobile phone)、平板电脑(pad)、笔记本电脑、电子阅读器、个人计算机(personal computer，PC)、个人数字助理(personal digital assistant，PDA)、桌面显示器、智能穿戴产品(例如，智能手表、智能手环)、虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、无人机等。家居式电子产品如为智能门锁、电视、遥控器、冰箱、充电家用小型电器(例如豆浆机、扫地机器人)等。车载式电子产品如为车载导航仪、车载高密度数字视频光盘(digital video disc，DVD)等。金融终端产品如为自动取款机(automated teller machine，ATM)机、自助办理业务的终端等。通信电子产品如为服务器、存储器、雷达、基站等通信设备。
以下为了方便说明，以电子设备为手机为例进行举例说明。如图1所示，电子设备1主要包括盖板11、显示屏12、中框13以及后壳14。后壳14和显示屏12分别位于中框13的两侧，且中框13和显示屏12设置于后壳14内，盖板11设置在显示屏12远离中框13的一侧，显示屏12的显示面朝向盖板11。
上述显示屏12可以是液晶显示屏(liquid crystal display，LCD)，在此情况下，液晶显示屏包括液晶显示面板和背光模组，液晶显示面板设置在盖板11和背光模组之间，背光模组用于为液晶显示面板提供光源。上述显示屏12也可以为有机发光二极管(organic light emitting diode，OLED)显示屏。由于OLED显示屏为自发光显示屏，因而无需设置背光模组。
上述中框13包括承载板131以及绕承载板131一周的边框132。上述电子设备1还可以包括印刷电路板(printed circuit boards，PCB)、电池、摄像头等电子元器件，印刷电路板、电池、摄像头等电子元器件可以设置在承载板131上。
上述电子设备1还可以包括设置于PCB上的系统级芯片(system on chip，SOC)、射频芯片等，PCB用于承载系统级芯片、射频芯片等，且与系统级芯片、射频芯片等电连接。其中，射频芯片可以包括滤波器、处理器等部分。处理器用于对各种信号进行处理，滤波器是射频信号处理的重要部分，用于通过特定频率的信号，让其他频率的信号受阻。
本申请的实施例提供一种滤波器，该滤波器可以应用于上述的电子设备1中，例如应用于电子设备1中的射频芯片中，本申请实施例提供的滤波器例如可以为低通波滤波器、高通滤波器、带通滤波器、带阻滤波器或有源滤波器等。
当然，本申请实施例提供的滤波器并不限定为集成在电子设备1中。滤波器也可以单独作为一个部件，或者，滤波器也可以和功率放大器等部件集成为一种模组(例如射频器件、射频模组、滤波器模组等)，滤波器与功率放大器耦接，进行信号处理和传输。
如图2所示，本申请实施例提供的滤波器10包括多个级联的兰姆波(lamb wave)谐振器100，这多个兰姆(lamb)波谐振器100可以具有不同的谐振频率，且可以通过串并联的方式级联在一起。图2还示意出了滤波器10的信号输入端Vi、信号输出端Vo以及接地端GND。
此处，lamb波谐振器100具有声速高(例如，12000m/s-15000m/s)、机电耦合系数大(例如，可达25％)等优点，多用于各种射频终端设备。而由具有不同谐振频率的串并联lamb波谐振器100级联构成的滤波器10具有通带插损小、带外陡峭度高及功率耐受性强等优点。
如图3A所示，示意一种lamb波谐振器100，包括压电层110、叉指换能器120以及移频层。图3B为图3A所示的lamb波谐振器100的导纳曲线图。通过导纳曲线图发现，除了主模一阶反对称(A1)模态以外，lamb波谐振器100中常常会出现三类杂模——横模(孔径方向的能量泄露)、一阶反对称模态横向三次(A1-3)谐波、零阶反对称(A0)模态横向高次谐波和零阶对称(S0)模态横向高次谐波。
其中，横模是由于声波能量在电极指的孔径方向(叉指换能器120中电极指的延伸方向，或者理解为图3A视角下垂直于当前截面的方向)发生泄漏导致的，超出谐振腔(电极指端部界定出谐振腔的范围)的声波称为声波泄露。声波沿孔径方向的泄露会在导纳图中A1模态的正反谐 振峰之间形成一系列小谐振峰，如图3B中虚线框中所示，会造成lamb波谐振器100通带内波动。
A1模态在横向会产生高次谐波，离A1模态最近的是A1-3谐波，如图3B所示，该谐波所在位置与通带的区间对应，常常会落在lamb波谐振器100的通带内，造成lamb波谐振器100通带内波动。
S0模态横向高次谐波为板波的一种，在A1模态的正反谐振峰之间，还会出现S0模态横向高次谐波，如图3B所示，这类杂模是S0模态横向高次谐波，S0模态横向高次谐波同样会造成lamb波谐振器100带内波动，损耗增加。应理解，在压电层中传播的波通常称为板波，在压电层表面传播的波通常称为表面波。
在不同lamb波谐振器100中，可能会出现S0模态横向高次谐波，也可能会出现A0模态横向高次谐波，A0模态横向高次谐波也为板波的一种，会出现在A1模态的正反谐振峰之间。A0模态横向高次谐波同样会造成lamb波谐振器100带内波动，损耗增加。当然，A0模态横向高次谐波和S0模态横向高次谐波也可能会同时出现，同样会造成lamb波谐振器100带内波动，损耗增加。
上述三类杂模均会造成lamb波谐振器100通带内波动，增加带内损耗，降低lamb波谐振器100性能。
以下列举可以抑制横模和A1-3谐波的实施例。
在一些技术中，如图4A所示，常规的lamb波谐振器100包括压电层110和叉指换能器120，叉指换能器120设置在压电层110的表面上。由于电极指的覆盖，会造成压电层110的表面上由电极指覆盖的区域和未覆盖的区域因结构不同，导致声阻抗失配(或者理解为是声阻抗不相等)，色散曲线(谐振频率随着波长变化生成的曲线)也产生失配，进而导致声波发生反射，造成杂散模态。
如图4B所示，提供一种lamb波谐振器100，包括压电层110和叉指换能器120，压电层110表面具有凹槽，叉指换能器120具有多个电极指，叉指换能器120的电极指设置在凹槽内。
图4C为图4A所示的lamb波谐振器100的导纳曲线图，图4D为图4B所示的lamb波谐振器100的导纳曲线图。对比图4C和图4D可知，通过将覆盖电极指的区域的压电层110刻蚀一定的深度，再进行电极指沉积，将覆盖电极指区域和未覆盖电极指区域的声阻抗调整到基本一致，可抑制A1-3谐波。
然而，使用下凹电极指结构抑制A1-3谐波，需要在压电层110上形成凹槽，基于压电层110材料的特殊性，在压电层110上形成凹槽的制备工艺较为复杂、工艺难度高。另外，下凹电极指结构的抑制原理为：通过减薄压电层110形成凹槽，来降低凹槽所在区域的声阻。而在凹槽中设置电极指，可以提高凹槽所在区域的声阻。降低的声阻量和提高的声阻量配合，使得凹槽所在区域的声阻与压电层110其他位置处(未设置电极指处)的声阻抗匹配(或者理解为相等)，从而达到抑制A1-3谐波的效果。因此，A1-3谐波的抑制效果和压电层110下凹的深度和电极指的厚度密切相关，需要准确控制压电层110的下凹深度和电极指的厚度，工艺容差小。否则二者声阻抗配合后，无法与压电层110其他位置处的声阻抗匹配，影响对A1-3谐波的抑制效果。图4B所示的lamb波谐振器100，在结构设计时主要用于抑制A1-3谐波。
本申请实施例提供一种lamb波谐振器100，如图5A所示，lamb波谐振器100包括：衬底140、压电层110、叉指换能器120以及介质层130。
衬底110的材料例如可以为铌酸锂(LiNbO3，LN)、钽酸锂(LiTaO3，LT)、石英(quartz)、硅(Si)、陶瓷(ceramics)或者玻璃(glass)等。陶瓷的主要成分例如包括硅酸盐和铝硅酸盐、耐熔金属氧化物和金属氮化物、硼化物等，玻璃的主要成分例如包括六二氧化硅合氧化钙合氧化钠(Na2O·CaO·6SiO2)。
其中，根据lamb波谐振器100类型的不同，衬底140的结构也不同，相关技术中的任一种衬底结构均适用于本申请。
示例的，如图5A所示，lamb波谐振器100为背刻蚀型结构。在这种结构下，衬底140在中 间区域具有开口，开口露出压电层110。
例如，可以使用背刻蚀工艺，在衬底140上形成开口，使中间区域的压电层110悬浮、中间区域的压电层110的下表面与空气接触。空气的声阻抗比较低，可将声波反射回压电层110，从而实现将声波能量限制在压电层110中。
或者，示例的，如图5B所示，lamb波谐振器100为空气隙型结构。在这种结构下，衬底140朝向压电层110一侧在中间区域具有凹槽141。
例如，使用刻蚀工艺，在压电层110上刻蚀出释放窗111，再通过释放工艺，在衬底140的中间区域形成凹槽141，使中间区域的压电层110悬浮、中间区域的压电层110的下表面与空气接触。空气的声阻抗比较低，可将声波反射回压电层110，从而实现将声波限制在压电层110中。
或者，示例的，如图5C所示，lamb波谐振器100为固态装配型结构。在这种结构下，衬底140的表面为平面。
lamb波谐振器100还包括设置在压电层110下方的布拉格反射结构(Bragg reflector)，布拉格反射结构包括交替设置的高声阻抗层和低声阻抗层。其中，低声阻抗层的材料例如可以为氧化锌、二氧化硅等，高声阻抗层的材料例如可以为重金属等。重金属是指密度大于4.5g/cm3的金属，包括金、银、铜、铁、汞、铅、镉等。声波在低声阻抗层和高声阻抗层的交界处发生反射，反射回压电层中。其中，低声阻抗层是相对高声阻抗层而言声阻抗略低的膜层，低声阻抗层和高声阻抗层的声阻抗均可能大于压电层。布拉格反射结构可将声波限制在压电层110中，从而实现将声波限制在压电层110中。
或者，示例的，如图5D所示，lamb波谐振器100为单层反射层型结构。在这种结构下，衬底140的表面为平面。
lamb波谐振器100还包括设置在压电层110下方的声波反射层，在对声波反射层和压电层110进行选材时，满足压电层110的声阻抗大于声波反射层的声阻抗，以实现声波在声波反射层朝向压电层110的表面处发生反射，反射回压电层110。
需要强调的是，本申请中，声波反射层的声阻抗小于压电层110的声阻抗即可，对声波反射层与衬底140之间声阻抗的大小关系不做限定。声波反射层的声阻抗可以小于衬底140的声阻抗，声波反射层的声阻抗也可以大于衬底140的声阻抗，声波反射层的声阻抗还可以等于衬底140的声阻抗。
声阻抗(acoustic impedance)是力学术语，指媒质在波阵面某个面积上的压强与通过这个面积的体积速度的复数比值，声阻抗的单位是帕斯卡·每平方米·秒(Pa·m-2s-1)。
压电层的声阻抗Z110和声波反射层的声阻抗Z120可以分别通过下面公式计算得到：
Z120＝v120*ρ120；
Z110＝v110*ρ110；
以lamb波为一阶反对称(A1)模态，声波反射层为各向同性材料为例：

其中，v120、v110为声波反射层和压电层110中的Z方向剪切波速，ρ120、ρ110为声波反射层和压电层110的密度，C44为压电层110的弹性劲度系数，E为声波反射层的杨氏模量(Young's modulus)，杨氏模量的单位为Pa、Mpa、Gpa，σ为声波反射层的泊松比Poisson's ratio)。
在一些实施例中，声波反射层朝向压电层110的表面的声波反射系数为R越大，对声波的限制效果越好。
关于声波反射系数R可以通过下面的公式计算得到：
其中，声波反射系数R与声波的限制效果相关。
在一些实施例中，声波反射系数R的取值范围为0.5≤R<0.86。例如，声波反射系数R的取值为0.6、0.65、0.7、0.75、0.8、0.85。
通过将声波反射系数R限定在大于等于0.5，可以较为有效的将声波限制在压电层110中，可使本申请实施例提供的lamb波谐振器100的性能与空气隙型lamb波谐振器的性能相近。
并且，既可以改善因声波反射系数R太小(小于0.5)，导致声波将不能被很好的限制在压电层110当中，或者用于限制声波的声波反射层需要很厚，工程上难以实现的问题。又可以改善因声波反射系数R太大(大于0.86)，导致声波反射层材料的密度和杨氏模量等参量比较小，材料比较柔软。在lamb波谐振器100加工过程中(例如键合压电层后退火)，声波反射层容易发生形变，造成其上方的压电层110出现褶皱或者碎裂，影响产品良率的问题。
其中，声波反射层的材料可以为满足声波反射系数R的任意材料。
在一些实施例中，声波反射层的材料为高分子材料(macromolecular material)。
高分子材料，也称为聚合物材料，是以高分子化合物为基体，再配有其他添加剂(助剂)所构成的材料。
示例的，声波反射层的材料包括聚酰亚胺(polyimide，PI)，聚二甲基硅氧烷(polydimethylsiloxane，PDMS)、聚甲基丙烯酸甲酯(polymethyl methacrylate，PMMA)、聚偏氟乙烯(polyvinylidene fluoride，PVDF)或者聚对苯二甲酸乙二醇酯(polyethylene glycol terephthalate，PET)等。
例如，可以采用旋涂、磁控溅射、物理气相沉积、化学气相沉积、外延生长等工艺，形成声波反射层。工艺简单，成本低，成品率高。
通过上述公式，如表1所示，可得到本申请实施例中几种可选的材料的声波反射系数R。
表1不同材料的声速、声阻抗与声波反射系数
在一些实施例中，声波反射层为单层膜层。
也可以理解为，声波反射层120是一层膜层，不是多层膜层层叠后构成的结构。
本申请实施例中，是基于声波反射层与压电层110之间的声阻抗差，使得声波在声波反射层朝向压电层110的表面反射。因此，声波反射层为单层膜层即可，结构简单制备工艺简单。
当然，声波反射层120也可以包括多层膜层，是由多层膜层层叠后构成的结构。
本申请实施例对声波反射层120的具体结构不做限定，多层膜层之间的声阻抗的关系也不做限定，能够使声波在声波反射层120朝向压电层130的表面发生反射即可。
在一些实施例中，声波反射层的最小厚度为y，最小厚度y可以通过下面的公式计算得到：
y＝77.75379*R2-173.22328*R+97.70404；
本申请实施例中，声波反射层的材料不同的情况下，声波反射层的声波反射系数R不同，声波反射层的最小厚度也不同。
在一些实施例中，声波反射层的厚度范围为3.5μm-30μm。
示例的，声波反射层的厚度为10μm、15μm、20μm或者25μm。
如图5A-图5D所示，本申请实施例提供的lamb波谐振器100中，压电层110的朝向叉指换能器120的表面为平面，无需在压电层110的表面形成用于放置叉指换能器120的凹槽。
在一些实施例中，压电层110的材料包括铌酸锂(LiNbO3，LN)、钽酸锂(LiTaO3，LT)、氮化铝(AlN)、氧化锌(ZnO)或者石英等压电材料中的一种或多种。压电层130的材 料可以是各切向的铌酸锂。
在一些实施例中，压电层110的材料为LiNbO3，其切向为Z切向。
Z切向的LiNbO3压电材料，可提高lamb波谐振器100的带宽。
在一些实施例中，压电层110的材料为LiNbO3，其欧拉角为(0，20，0)到(0，40，0)。
示例的，压电层110的材料为LiNbO3，其欧拉角为(0，25，0)、(0，30，0)、(0，35，0)。
其中，欧拉角中的三个数字(α，β，γ)分别代表直拉出来的单晶先绕z轴旋转α，再绕x轴旋转β，最后再绕z轴旋转γ，这样就确定了晶体的切向。因此，欧拉角确定了，晶体的切向就确定了。
压电层130材料的欧拉角在上述范围，可以提高lamb波谐振器100的谐振特性。
在一些实施例中，压电层110的厚度为0.2μm-1μm。
示例的，压电层110的厚度为0.3μm、0.4μm、0.5μm、0.6μm、0.7μm、0.8μm、0.9μm。
压电层110的厚度与lamb波谐振器的频率直接相关，压电层越薄，器件频率越高。本申请将压电层的厚度限定在0.2μm-1μm，可使lamb波谐振器应用于高频中。
叉指换能器120设置在压电层110远离衬底140一侧，例如，叉指换能器120设置在压电层110远离衬底140的表面上。
叉指换能器120可以理解为是在压电层110表面上形成形状像两只手的手指交叉状的金属图案，它的作用是实现声-电换能。在一种实施例中，如图6A所示，上述叉指换能器120包括相对设置的第一汇流条(busbar)121a和第二汇流条122a、多个第一电极指(interdigitated transducer，IDT)121b、以及多个第二电极指122b。第一汇流条121a和第二汇流条122a的延伸方向与第一方向X平行，第一电极指121b的延伸方向与第二方向Y平行，第一电极指121b从第一汇流条121a向第二汇流条122a凸出，多个第一电极指121b与第一汇流条121a耦接。第二电极指122b的延伸方向与第二方向Y平行，第二电极指122b从第二汇流条122a向第一汇流条121a凸出，多个第二电极指122b与第二汇流条122a耦接。第一方向X与第二方向Y相交。其中，本申请实施例中的平行包括近似平行，工艺误差(例如±5°)范围内的偏差均属于本申请实施例中的平行。
其中，多个第一电极指121b和多个第二电极指122b，在第一汇流条121a和第二汇流条122a之间沿第一方向X依次交替排布，第一电极指121b和第二电极指122b之间不接触。
上述“多个第一电极指121b和多个第二电极指122b在第一汇流条121a和第二汇流条122a之间沿第一方向X依次交替排布”指的是：在第一汇流条141a和第二汇流条142a之间，每两个第一电极指141b之间设有一个第二电极指142b、每两个第二电极指142b之间设有一个第一电极指141b。
对于叉指换能器120中第一电极指121b的数量和第二电极指122b的数量不进行限定，可以根据需要进行设置。多个第一电极指121b可以是等间距排布，也可以是非等间距排布。同样的，多个第二电极指122b可以是等间距排布，也可以是非等间距排布。以第一电极指121b为例，多个第一电极指121b非等间距排布指的是至少一对相邻的第一电极指121b之间的间距与另一对相邻的第一电极指121b之间的间距不相同。
此外，多个第一电极指121b和多个第二电极指122b依次交替排布，可以是相邻第一电极指121b和第二电极指122b之间的间距均相同；也可以是多对相邻的第一电极指121b和第二电极指122b之间的间距不完全相同，即至少一对相邻的第一电极指121b和第二电极指122b之间的间距与另一对相邻的第一电极指121b和第二电极指122b之间的间距不相同。
在一些实施例中，相邻第一电极指121b和第二电极指122b之间的间距为2μm-10μm。
示例的，相邻第一电极指121b和第二电极指122b之间的间距为-4μm、4μm-5μm、5μm-6μm、6μm-7μm、7μm-8μm、8μm-9μm或者9μm-10μm。
由于第一电极指141b和第二电极指142b之间的间距直接影响lamb波谐振器100的频率， 同时对lamb波谐振器100的带宽也有影响。一般来说间距越大，带宽越大。因此，通过将相邻第一电极指141b和第二电极指142b之间的间距限定在2μm-10μm，可以使lamb波谐振器100工作在第五代移动通信技术(5th generation mobile communication technology，5G)频段，具有较宽的带宽。
在一些实施例中，第一电极指141b的宽度为200nm-1000nm，第二电极指142b的宽度为200nm-1000nm。
示例的，第一电极指141b和第二电极指142b的宽度为200nm-300nm之间、300nm-400nm之间、400nm-500nm之间、500nm-600nm之间、600nm-700nm之间、700nm-800nm之间、800nm-900nm之间或者900nm-1000nm之间。
由于占空比主要影响lamb波谐振器100的带宽，对lamb波谐振器100的频率也有影响。而占空比＝电极指的宽度/(电极指的宽度+电极指之间的间距)，在电极指之间的间距确定的情况下，调整电极指的宽度，可以调整lamb波谐振器100的带宽和频率。因此，通过将相邻第一电极指141b和第二电极指142b的宽度限定在200nm-1000nm，可以使lamb波谐振器100工作在5G频段，且具有较宽的带宽。
可以理解的是，第一电极指121b和第二电极指122b之间的间距(pitch)、第一电极指121b和第二电极指122b的指条宽度主要受光刻和显影工艺的影响，通过调整第一电极指121b和第二电极指122b之间的间距、第一电极指121b和第二电极指122b的指条宽度，可以改变lamb波谐振器100的谐振频率和带宽，因此可以使得特定频率的电子信号得以通过lamb波谐振器100，而其他频率的电子信号则会被lamb波谐振器100滤除。
需要说明的是，第一汇流条121a、第一电极指121b、第二汇流条122a和第二电极指122b可以同时制作。也可以先制作第一汇流条121a和第一电极指121b，再制作第二汇流条122a和第二电极指122b。或者，先制作第二汇流条122a和第二电极指122b，再制作第一汇流条121a和第一电极指121b。
其中，第一电极指121b和第二电极指122b材料可以包括铝(Al)、铜(Cu)、铂(Pt)、金(Au)、镍(Ni)、钛(Ti)、Ag(银)、铬(Cr)、钼(Mo)、钨(W)、钽(Ta)等的一种或多种。
其中，本申请实施例提供的叉指换能器120中，第一电极指121b和第二电极指122b与压电层110相交的侧面与压电层110垂直。但受工艺限制，第一电极指121b和第二电极指122b的侧面也可以与压电层110具有一定倾斜角。示例的，如图6B(图5D中M位置处的放大图)所示，第一电极指121b和第二电极指122b的侧面与压电层110之间的夹角θ的取值为70°<θ≤90°。
结合图6A可知，图5A-图5D的截面图中示意出了叉指换能器120的第一电极指121b和第二电极指122b。另外，本申请实施例附图中，第一方向X为第一电极指121b和第二电极指122b的排布方向，第二方向Y为第一电极指121b和第二电极指122b的延伸方向，第三方向Z为lamb波谐振器100的厚度方向。第一方向X与第二方向Y相交，第三方向Z与第一方向X和第二方向Y所在平面垂直。
以下为了便于说明，以空气隙型的lamb波谐振器100为例，对介质层130的结构进行示意说明。
介质层130与叉指换能器120位于压电层110的同一侧，关于介质层130的结构，在一些实施例中，如图7A所示，介质层130包括第一部分131和第二部分132，第一部分131设置在压电层110的表面，且位于第一电极指121b和第二电极指122b的外围。第二部分132位于叉指换能器120的顶面(远离压电层110的表面)。
或者理解为，在叉指换能器120的表面成膜形成介质层130，介质层130的一部分作为本申请实施例中的第一部分131落入叉指换能器120的缝隙处，与压电层110直接接触。介质层130的另一部分作为本申请实施例中的第二部分132落在叉指换能器120的表面，与叉指换能器120接触。
也就是说，介质层130中，与压电层110接触的部分为第一部分131，与叉指换能器120接触的部分为第二部分132。
在一些实施例中，第二部分132在压电层110表面具有第一投影，叉指换能器120在压电层110表面具有第二投影，第二投影包含第一投影。或者理解为，第二部分132设置在叉指换能器120的顶面。
示例的，第一投影与第二投影重合。或者，示例的第二投影覆盖第一投影。
从俯视图上来看，如图7B所示，介质层130中第二部分133的形状与叉指换能器120的形状基本重合，除第二部分133以外的结构属于第一部分131。
如图6B所示，在第一电极指121b和第二电极指122b的侧面与压电层110之间的夹角θ小于90°的情况下，第一部分131与第二部分132的交界面应与第一电极指121b和第二电极指122b顶面的边界对应。也就是说，第二部分132的边界与第一电极指121b和第二电极指122b顶面的边界对应。
当然，工艺误差范围内的位置偏移均属于本申请实施例保护的范围。工艺误差偏移例如可以是在图6B中视角下，交界面左右偏移150nm。
在一些实施例中，第一部分131的厚度为S1，第二部分132的厚度S2，S1>S2。
对本申请实施例提供的lamb波谐振器100和相关技术提供的lamb波谐振器100进行有限元仿真，得到的导纳曲线如图8A所示。其中，实线为本申请实施例提供的lamb波谐振器100
(S1>S2)的导纳曲线，点划线为相关技术提供的lamb波谐振器100(S1＝S2)的导纳曲线。
从相关技术的lamb波谐振器100(S1＝S2)的导纳曲线可以看出，在A1模态的正反谐振峰之间，存在明显的A0模态横向高次谐波和S0模态横向高次谐波(或者称为，杂散模态)。同时，在A1模态的正谐振峰左边，也出现了一个杂散模态。从本申请实施例提供的lamb波谐振器100(S1>S2)的导纳曲线可以看出，A1模态的正反谐振峰之间的A0模态横向高次谐波和S0模态横向高次谐波受到很好的抑制，并且A1模态的正谐振峰左边的杂散模态也受到很好的抑制，甚至被完全抑制掉，lamb波谐振器100的导纳曲线平滑，性能较好。
因此，本申请实施例提供的lamb波谐振器100，通过减薄介质层130中位于叉指换能器120上方的第二部分132的厚度S2，可达到抑制lamb波谐振器100中A0模态横向高次谐波和S0模态横向高次谐波等板波散模态的效果，提高通带内的平整度，降低损耗，提升lamb波谐振器100的性能。
而且，本申请实施例提供的lamb波谐振器100，是减薄了介质层130中位于叉指换能器120上方的第二部分132的厚度S2，相当于对介质层130进行处理。与图4B所示实施例中对压电层110进行处理相比，介质层130的材料为介质材料，在半导体领域中，对介质材料刻蚀处理的工艺比较成熟，制备本申请的介质层130所采用的工艺均可以采用相关技术中比较成熟的工艺。但是压电层110的材料为压电材料，在半导体领域中，对压电材料刻蚀处理的工艺比较少，需要进一步对工艺进行研究控制才能达到目的。因此，本申请实施例提供的lamb波谐振器100的制备工艺简单，且工艺难度低，制备成本低、可提高lamb波谐振器100的良率。另外，图8B示意出本申请实施例提供的lamb波谐振器100的导纳曲线和图4B所示的lamb波谐振器100的导纳曲线，对比两个导纳曲线可以发现，本申请实施例提供的lamb波谐振器100对A0模态横向高次谐波和S0模态横向高次谐波等板波散模态的抑制效果更好。
在一个实施例中，lamb波谐振器100中包括移频层，移频层用于调整lamb波谐振器100的频率。移频层设置在叉指换能器120远离压电层110一侧。
其中，移频层的材料，例如可以是氮化硅(SiN)、氧化铝(Al2O3)或者氧化硅(SiO2)。
可以直接将移频层作为本申请实施例提供的lamb波谐振器100中的介质层130，对移频层进行处理即可，无需新增膜层，对lamb波谐振器100的改动较小。
在一个实施例中，设置移频层(例如，减薄的移频层)的lamb波谐振器100可以应用于n77频带(3.3GHz-4.2GHz)、n78频带(3.3GHz-3.8GHz)、n79频带(4.4GHz-5.0GHz)等第五代移动通信技术(5th generation mobile communication technology，5G)频段中、工作频率在450MHz 到6000MHz的6G以下频段(sub-6G频段)的滤波器。
关于S1和S2的取值，在一些实施例中，如图9A所示，S2＝0。
或者理解为，介质层130包括第一部分131，第一部分131设置在压电层110的表面，且位于第一电极指121b和第二电极指122b的外围。介质层130中不包括位于叉指换能器120上方的第二部分132。
从俯视图上看，介质层130(第一部分131)的结构如图9B所示，介质层130中具有镂空图案，镂空图案的俯视图和叉指换能器120的俯视图基本重合。
经有限元仿真发现，完全去除介质层130中位于叉指换能器120上方的第二部分132，也可以达到抑制lamb波谐振器100中A0模态横向高次谐波和S0模态横向高次谐波等杂散模态的板波的效果。
在另一些实施例中，如图9C所示，0<S2<S1。
或者理解为，介质层130包括第一部分131和第二部分132，第一部分131设置在压电层110的表面，且位于第一电极指121b和第二电极指122b的外围。第二部分132位于叉指换能器120的顶面。
对S1和S2进行不同取值后，对lamb波谐振器100进行有限元仿真，得到下表2。
表2不同S1和S2组合下的A0模态横向高次谐波和S0模态横向高次谐波的抑制情况
其中，表1中对应数字1的S1和S2组合，代表在相应的S1和S2取值下，A0模态横向高次谐波和S0模态横向高次谐波的抑制较好(可以理解为，例如，A0模态横向高次谐波和S0模态横向高次谐波的峰峰值小于5dB)。表1中对应数字2的S1和S2组合，代表在相应的S1核S2取值下，A0模态横向高次谐波和S0模态横向高次谐波的几乎被完全抑制(可以理解为，例如，A0模态横向高次谐波和S0模态横向高次谐波的峰峰值小于2.5dB)。
示例的，在第一部分131的厚度S1的取值为115nm，第二部分132的厚度S2的取值为50nm的情况下，A0模态横向高次谐波和S0模态横向高次谐波的几乎被完全抑制。在第一部分131的厚度S1的取值为115nm，第二部分132的厚度S2的取值为55nm的情况下，A0模态横向高次谐波和S0模态横向高次谐波的抑制效果较好。
基于此，S1和S2之差，对A0模态横向高次谐波和S0模态横向高次谐波的抑制效果有一定的影响。在一些实施例中，50nm≤S1-S2≤S1。
示例的，S1-S2的取值为55nm、60nm、65nm、70nm、75nm、80nm、85nm、90nm、95nm、100nm、105nm、110nm、115nm、120nm、125nm、130nm、135nm、140nm、145nm、150nm、155nm、160nm、165nm、170nm、175nm、180nm、185nm、190nm、195nm。
通过将第一部分131的厚度与第二部分132的厚度之差限定在50nm-S1，可较好的实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制。
固定第一部分131的厚度S1＝115nm，对第二部分132的厚度S2在5nm-85nm范围内进行取值，通过有限元仿真出不同S2下lamb波谐振器100的导纳曲线。如图10A-图10C示意出第一部分131的厚度S1＝115nm，S2为5nm、45nm、85nm时lamb波谐振器100的导纳曲线。发现S2从5nm变化到85nm，A1模态的反谐振频率几乎不变，正谐振频率的波动在5MHz以内。
也就是说，在第一部分131的厚度S1固定的情况下，第二部分132的厚度S2可以有一个较大的变化范围，在这个较大的范围内，均可实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制。而并非固定为某一数值或者一个较小的范围，才能达到对A0模态横向高次谐波和S0模态横向高次谐波的抑制。
另外，通过表1可知，第一部分131的厚度S1的取值也可以在一个较大的范围内，在这个较大的范围内，均可实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制。而并非固定为某一数值或者一个较小的范围，才能达到对A0模态横向高次谐波和S0模态横向高次谐波的抑制。
通过上述描述可知，本申请实施例提供的lamb波谐振器100中介质层130的第一部分131的厚度S1有一个较大的取值范围，介质层130的第二部分132的厚度S2也有一个较大的取值范围，而S1-S2也有一个较大的取值范围。因此，本申请实施例提供的lamb波谐振器100中介质层130的厚度取值范围广，且lamb波谐振器100对工艺误差有较大的容纳范围。
在一些实施例中，20nm≤S1≤200nm。
示例的，介质层130第一部分131的厚度S1的取值为30nm-50nm、50nm-70nm、70nm-90nm、90nm-100nm、100nm-120nm、120nm-140nm、140nm-145nm、145nm-150nm、150nm-155nm、155nm-160nm、160nm-165nm、165nm-170nm、170nm-175nm、175nm-180nm、180nm-185nm、185nm-190nm、190nm-195nm、195nm-200nm。
通过将介质层130第一部分131的厚度S1的取值限定在20nm-200nm，既可实现对A0模态横向高次谐波和S0模态横向高次谐波的抑制，又不会过分增加lamb波谐振器100的厚度。
在一些实施例中，65nm≤S1-S2≤S1，110nm≤S1≤140nm。
其中，若为了确保对A0模态横向高次谐波和S0模态横向高次谐波的抑制效果，例如可以避开S1＝135nm的情况。也就是说，在设计lamb波谐振器100，第一部分131的厚度不设计为135nm。
通过将S1-S2的取值限定在大于65nm，将S1的取值限定在110nm-140nm，几乎可以实现将A0模态横向高次谐波和S0模态横向高次谐波完全抑制，lamb波谐振器100的性能较优。
在一些实施例中，叉指换能器120的厚度的取值范围为60nm-140nm。
示例的，叉指换能器120的厚度的取值为70nm-75nm、75nm-80nm、80nm-85nm、85nm-90nm、90nm-95nm、95nm-100nm、100nm-105nm、105nm-110nm、110nm-115nm、115nm-120nm、120nm-125nm、125nm-130nm、130nm-135nm、135nm-140nm。
固定第一部分131的厚度S1＝115nm，第二部分132的厚度S2＝0nm。叉指换能器120的材料为铝，对叉指换能器120的厚度S3在20nm-160nm范围内进行取值，通过有限元仿真出不同 厚度的叉指换能器120对应的lamb波谐振器100的导纳曲线。图11A-图11C中示意出叉指换能器120的厚度S3为60nm、100nm、140nm时lamb波谐振器100的导纳曲线。发现改变叉指换能器120的厚度S3，对A0模态横向高次谐波和S0模态横向高次谐波仍然有抑制效果。其中，叉指换能器120的厚度在60nm-140nm范围内时，A0模态横向高次谐波和S0模态横向高次谐波的抑制效果较好。
因此，本申请实施例提供的lamb波谐振器100中叉指换能器120的厚度取值范围较广，lamb波谐振器100可以适用于对叉指换能器120有不同厚度需要的场景中，应用范围广。
通过上述描述可知，本申请实施例提供的lamb波谐振器100中介质层130第一部分131的厚度S1的取值范围较广、介质层130第一部分131厚度S1与第二部分厚度S2之差的取值范围广、叉指换能器120的取值范围也比较广。
因此，在不同厚度的组合下，介质层130会出现如图9C所示的，第一部分131的顶面a1与第二部分132的顶面a2平齐的情况。
第一部分131的顶面a1，可以理解为是第一部分131远离压电层110的表面。第二部分132的顶面a2，可以理解为是第二部分132远离压电层110的表面。
第一部分131的顶面a1与第二部分132的顶面a2平齐，可以理解为，第一部分131的顶面a1到压电层110的距离与第二部分132的顶面a2到压电层110的距离相等。
在不同厚度的组合下，介质层130也会出现如图12所示的，第一部分131的顶面a1低于第二部分132的顶面a2的情况。
类似地，第一部分131的顶面a1低于第二部分132的顶面a2，可以理解为，第一部分131的顶面a1到压电层110的距离小于第二部分132的顶面a2到压电层110的距离。
在不同厚度的组合下，介质层130也会出现如图7A所示的，第一部分131的顶面a1高于第二部分132的顶面a2的情况。
在一些实施例中，本申请实施例提供的lamb波谐振器100，介质层130中第一部分131各位置处的厚度相等，第二部分132各位置处的厚度相等。
当然，此处相等，并不限定为绝对相等，近似相等也属于本申请实施例保护的范围。或者说，工艺误差范围内的厚度变化，均属于本申请实施例保护的范围。例如，±3％范围内的厚度变化，均属于本申请实施例保护的范围。
关于介质层130的材料，在一些实施例中，介质层130的材料包括氮化硅(Si3N4)、氧化铝(Al2O3)或者氧化硅(SiO2)。
此处需要释明的是，本申请实施例对介质层130的大小不做限定，如图12所示，介质层130可以仅位于压电层110的中心区域，包围叉指换能器120即可。在一些实施例中，介质层130也可以位于压电层110在释放窗111两侧的区域上。
另外，本申请实施例提供的lamb波谐振器100，介质层130同时可以作为lamb波谐振器100的移频层使用。
在这种情况下，介质层130的材料例如可以是Si3N4、Al2O3或者SiO2。
本申请中lamb波谐振器100包括移频层的情况下，无需改变lamb波谐振器100中其他膜层的结构，通过调整移频层的厚度，可将lamb波谐振器100的频率调整至需要值。
本申请实施例提供的lamb波谐振器100，介质层130同时可以作为lamb波谐振器100的温度补偿层使用。
在这种情况下，介质层130的材料例如可以是SiO2。
本申请中lamb波谐振器100包括温度补偿层的情况下，可通过温度补偿层对lamb波谐振器100进行温度补偿，使得lamb波谐振器100的频率温度系数(TCF)的绝对值下降。
本申请实施例提供的lamb波谐振器100，介质层130同时可以作为lamb波谐振器100的钝化层使用。
在这种情况下，介质层130的材料例如可以是Si3N4、Al2O3或者SiO2。
本申请中lamb波谐振器100包括钝化层的情况下，可通过钝化层对lamb波谐振器100进行 保护，延长lamb波谐振器100的使用寿命。
在这种情况下，示例的，压电层110朝向衬底140一侧还可以设置有温度补偿层或者移频层。
在一些实施例中，如图13所示，lamb波谐振器100包括介质层130的基础上，还包括钝化层150，钝化层150设置在介质层130远离压电层110一侧，钝化层150的厚度的取值范围为1nm-50nm。
钝化层150的材料，例如可以是Si3N4、Al2O3或者SiO2。
通过设置钝化层150，可对钝化层150与衬底140之间的膜层进行保护，延长lamb波谐振器100的使用寿命。
下面，对本申请实施例提供的lamb波谐振器100的制备方法进行示意说明。
在一些实施例中，如图14所示，lamb波谐振器100的制备方法包括：
S10、形成位于衬底140上的压电层110。
其中，根据lamb波谐振器100类型的不同，衬底140的结构也不同，衬底140与压电层110的制备顺序也不同。可参考上述关于衬底140及其制备方法的描述，此处不再赘述。
例如，可以采用采磁控溅射、物理气相沉积、化学气相沉积、外延生长或者晶体间的键合(bonding)等工艺形成压电层110。
S20、在压电层110远离衬底140的一侧形成叉指换能器120。
本申请实施例对叉指换能器120的制备工艺不做限定，相关技术中用于制备叉指换能器120的工艺均适用于本申请。
S30、在压电层110远离衬底140的一侧形成介质层130。
在一些实施例中，介质层130包括第一部分131，第一部分131设置在压电层110的表面，且位于第一电极指121b和第二电极指122b的外围。
在这种情况下，示例的，如图15所示，步骤S30包括：
S31、形成叉指换能器120后，在叉指换能器120远离衬底140一侧形成介质膜，介质膜覆盖叉指换能器120和压电层110。
S32、对介质膜进行刻蚀，露出叉指换能器120，以形成介质层130。
在另一些实施例中，介质层130包括第一部分131和第二部分132。第一部分131设置在压电层110的表面，第二部分132设置在叉指换能器120的表面。
示例的，如图15所示，步骤S30包括：
S31、形成叉指换能器120后，在叉指换能器120远离压电层110一侧形成介质膜。
在这种情况下，上述介质膜可以理解为是第一介质膜，第一介质膜覆盖叉指换能器120和压电层110，第一介质膜的厚度与待形成的第二部分132的厚度基本相等。
S32′、在上述介质膜(第一介质膜)上形成第二介质膜，第二介质膜位于第一电极指121b和第二电极指122b的外围，以形成介质层130。
其中，第一介质膜位于压电层110表面的部分以及第二介质膜构成介质层130的第一部分131，第一介质膜位于叉指换能器120顶面的部分作为介质层130的第二部分132。
通过调整第二介质膜的厚度，可以实现第一部分131的顶面a1与第二部分132的顶面a2平齐。或者，第一部分131的顶面a1低于第二部分132的顶面a2。或者，第一部分131的顶面a1高于第二部分132的顶面a2。
或者，示例的，如图15所示，步骤S30包括：
S31、形成叉指换能器120后，在叉指换能器120远离压电层110一侧形成介质膜。
在这种情况下，上述介质膜可以理解为是第三介质膜，第三介质膜覆盖叉指换能器120和压电层110。根据后续使用的减薄工艺的不同，第三介质膜的厚度也不同。下文结合减薄工艺，对第三介质膜的厚度进行说明。
S32″、对上述介质膜(第三介质膜)位于叉指换能器120顶面的部分进行减薄，以形成介质层130。
其中，第三介质膜位于压电层110表面的部分作为第一部分131，第三介质膜减薄后的部分作为第二部分132。
关于减薄工艺，例如，可以通过化学机械抛光工艺(chemical mechanical polishing，CMP)对第三介质膜整体进行减薄，直至第三介质膜位于叉指换能器120顶面的部分的厚度满足待形成的第二部分132的厚度，停止减薄。
在这种情况下，第三介质膜的厚度应大于待形成的第一部分131的厚度。
可以理解的是，采用CMP工艺进行减薄后，形成的介质层130的第一部分131的顶面a1与第二部分132的顶面a2平齐。
关于减薄工艺，或者，可以采用刻蚀、腐蚀等工艺，对第三介质膜位于压电层110表面的部分进行选择性减薄，以形成第二部分132。
在这种情况下，第三介质膜的厚度应等于待形成的第一部分131的厚度。
通过控制减薄的程度，可以实现第一部分131的顶面a1与第二部分132的顶面a2平齐。或者，第一部分131的顶面a1低于第二部分132的顶面a2。或者，第一部分131的顶面a1高于第二部分132的顶面a2。
本申请实施例提供的lamb波谐振器100的制备方法，通过控制形成介质层130时的工艺，可形成本申请实施例所需的介质层130，以提供一种可以抑制A0模态横向高次谐波和S0模态横向高次谐波的lamb波谐振器。对介质材料进行处理，工艺简单，易于实现，良品率高。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何在本申请揭露的技术范围内的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (19)

  1. 一种兰姆lamb波谐振器，其特征在于，包括：
    压电层；
    叉指换能器，设置于所述压电层的一侧；所述叉指换能器包括多个第一电极指和多个第二电极指，所述多个第一电极指和所述多个第二电极指沿第一方向交替排布；所述第一方向与所述第一电极指和所述第二电极指的延伸方向相交；
    介质层，与所述叉指换能器位于所述压电层的同一侧；所述介质层包括第一部分，所述第一部分设置在所述压电层的表面，且位于所述第一电极指和所述第二电极指的外围。
  2. 根据权利要求1所述的lamb波谐振器，其特征在于，所述介质层还包括第二部分，所述第二部分位于所述叉指换能器的顶面；
    所述第一部分的厚度为S1，所述第二部分的厚度S2，S1>S2。
  3. 根据权利要求2所述的lamb波谐振器，其特征在于，S1-S2≥50nm。
  4. 根据权利要求1-3任一项所述的lamb波谐振器，其特征在于，所述第一部分的厚度为S1，20nm≤S1≤200nm。
  5. 根据权利要求2-4任一项所述的lamb波谐振器，其特征在于，S1-S2≥65nm；110nm≤S1≤140nm。
  6. 根据权利要求1-5任一项所述的lamb波谐振器，其特征在于，所述叉指换能器的厚度的取值范围为60nm-140nm。
  7. 根据权利要求2-6任一项所述的lamb波谐振器，其特征在于，
    所述第一部分与所述第二部分的顶面平齐；
    或者，
    所述第一部分的顶面高于所述第二部分的顶面；
    或者，
    所述第一部分的顶面低于所述第二部分的顶面。
  8. 根据权利要求2-7任一项所述的lamb波谐振器，其特征在于，所述第二部分在所述压电层上具有第一投影，所述叉指换能器在所述压电层上具有第二投影，所述第二投影包含所述第一投影。
  9. 根据权利要求1-8任一项所述的lamb波谐振器，其特征在于，所述lamb波谐振器还包括钝化层，所述钝化层设置在所述介质层远离所述压电层一侧，所述钝化层的厚度的取值范围为1nm-50nm。
  10. 根据权利要求1-9任一项所述的lamb波谐振器，其特征在于，所述介质层的材料包括SiO2、Si3N4或者Al2O3。
  11. 一种滤波器，其特征在于，包括多个级联的lamb波谐振器；其中，所述lamb波谐振器为如权利要求1-10任一项所述的lamb波谐振器。
  12. 一种射频模组，其特征在于，包括滤波器和功率放大器，所述滤波器与所述功率放大器耦接；所述滤波器为权利要求11所述的滤波器。
  13. 一种电子设备，其特征在于，包括滤波器和电路板，所述滤波器设置在所述电路板上；所述滤波器为权利要求11所述的滤波器。
  14. 一种lamb波谐振器的制备方法，其特征在于，包括：
    形成压电层；
    在所述压电层的一侧形成叉指换能器；所述叉指换能器包括多个第一电极指和多个第二电极指，所述多个第一电极指和所述多个第二电极指沿第一方向交替排布；所述第一方向与所述第一电极指和所述第二电极指的延伸方向相交；
    在所述压电层的一侧形成介质层，所述介质层与所述叉指换能器位于所述压电层的同一侧；所述介质层包括第一部分，所述第一部分设置在所述压电层的表面，且位于所述第一电极指和所述第二电极指的外围。
  15. 根据权利要求14所述的制备方法，其特征在于，所述介质层还包括第二部分，所述第二部分位于所述叉指换能器的顶面；所述第一部分的厚度大于所述第二部分的厚度；
    在所述压电层一侧形成介质层，包括：
    形成所述叉指换能器后，在所述叉指换能器远离所述压电层一侧形成第一介质膜；所述第一介质膜覆盖所述叉指换能器和所述压电层；
    在所述第一介质膜上形成第二介质膜，所述第二介质膜位于所述第一电极指和所述第二电极指的外围，以形成所述介质层；所述第一介质膜位于所述压电层表面的部分以及所述第二介质膜构成所述第一部分，所述第一介质膜位于所述叉指换能器顶面的部分作为所述第二部分。
  16. 根据权利要求14所述的制备方法，其特征在于，所述介质层还包括第二部分，所述第二部分位于所述叉指换能器的顶面；所述第一部分的厚度大于所述第二部分的厚度；
    在所述压电层一侧形成介质层，包括：
    形成所述叉指换能器后，在所述叉指换能器远离所述压电层一侧形成第三介质膜；所述第三介质膜覆盖所述叉指换能器和所述压电层；
    对所述第三介质膜位于所述叉指换能器顶面的部分进行减薄，以形成所述介质层；所述第三介质膜位于所述压电层表面的部分作为所述第一部分，所述第三介质膜减薄后的部分作为所述第二部分。
  17. 根据权利要求15或16所述的制备方法，其特征在于，所述第一部分的厚度为S1，所述第二部分的厚度S2，S1>S2。
  18. 根据权利要求17所述的制备方法，其特征在于，S1-S2≥50nm。
  19. 根据权利要求15-18任一项所述的制备方法，其特征在于，所述第二部分在所述压电层上具有第一投影，所述叉指换能器在所述压电层上具有第二投影，所述第二投影包含所述第一投影。
PCT/CN2023/112727 2022-08-27 2023-08-11 兰姆波谐振器及制备方法、滤波器、射频模组、电子设备 WO2024046099A1 (zh)

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