WO2024001757A1 - 一种高频声波谐振器及应用其的滤波器 - Google Patents
一种高频声波谐振器及应用其的滤波器 Download PDFInfo
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- WO2024001757A1 WO2024001757A1 PCT/CN2023/099857 CN2023099857W WO2024001757A1 WO 2024001757 A1 WO2024001757 A1 WO 2024001757A1 CN 2023099857 W CN2023099857 W CN 2023099857W WO 2024001757 A1 WO2024001757 A1 WO 2024001757A1
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- acoustic resonator
- frequency acoustic
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- 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
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02047—Treatment of substrates
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02062—Details relating to the vibration mode
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/56—Monolithic crystal filters
- H03H9/564—Monolithic crystal filters implemented with thin-film techniques
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/58—Multiple crystal filters
- H03H9/582—Multiple crystal filters implemented with thin-film techniques
Definitions
- the invention relates to the field of microelectronics technology, and in particular to a high-frequency acoustic wave resonator and a filter using the same.
- Acoustic resonators include Surface Acoustic Wave (SAW) resonators and Bulk Acoustic Wave (BAW); resonators have been widely used in the communications field because of their small size, large bandwidth, and high Q value. Among them, the resonant frequency of the BAW resonator is inversely proportional to the thickness, and higher frequencies can be easily achieved by thinning the film.
- SAW Surface Acoustic Wave
- BAW Bulk Acoustic Wave
- the traditional solid-state assembled bulk acoustic resonator uses a multi-layer Bragg reflective layer structure to confine the acoustic energy within the piezoelectric film, but this greatly increases the process difficulty and Cost of production.
- a high-frequency acoustic resonator on one hand, which includes a support substrate, a bottom electrode, and a support substrate, which are stacked in sequence from bottom to top. Piezoelectric film and interdigital transducers;
- the interdigital transducer includes a first bus bar and a plurality of first electrodes arranged at intervals; the same side of the plurality of first electrodes is connected to the first bus bar;
- the product of the spacing distance between the centers of adjacent first electrodes among the plurality of first electrodes and the frequency of the target mode is less than the sound speed of the support substrate; the target mode is excited by the high-frequency acoustic resonator under the action of a longitudinal electric field advanced mode.
- the resonant frequency of the target mode is determined by the thickness of the piezoelectric film, the bulk acoustic wave speed of the piezoelectric film, the type of load, and the thickness of the load; the load includes the interdigital transducer;
- the phase velocity of the target mode along the first direction is determined by the period of the interdigital transducer and the resonant frequency, and the phase velocity in the first direction is greater than or equal to 5000 meters/second; the period of the interdigital transducer is The spacing distance between the centers of adjacent first electrodes among the plurality of first electrodes; the first direction is a direction parallel to the surface of the piezoelectric film.
- the wave type corresponding to the target mode is one of high-order Lamb waves, high-order horizontal shear waves, and high-order Rayleigh modes.
- the slow shear wave sound speed in the second direction of the support substrate is greater than the phase velocity of the target mode along the first direction; the second direction is parallel to the first direction and perpendicular to the first direction.
- the direction of the electrode is configured
- the first side of the first bus bar is the side close to the bottom electrode.
- insulation is also included;
- the piezoelectric film is provided with a first through hole
- the first through hole corresponds to the first bus bar, and the insulating member is disposed in the first through hole;
- the material of the insulating member is a non-piezoelectric insulating material.
- a bonding layer is also included;
- the bonding layer is located between the support substrate and the bottom electrode
- the bonding layer includes non-metallic materials and metallic materials.
- a low-sound velocity dielectric layer is also included;
- the low sound velocity dielectric layer is located between the support substrate and the bottom electrode;
- the low sound speed dielectric layer includes non-metallic materials and metallic materials.
- the support substrate includes a stacked first substrate and a high-sonic velocity substrate
- the material of the first substrate is a material that is easy to be formed and processed
- the material of the high-sonic velocity substrate is one of silicon carbide, diamond, diamond-like diamond, sapphire, aluminum nitride and silicon nitride with different crystal forms and different cut shapes.
- the thickness of the high-sonic velocity substrate is greater than or equal to 0.5 times the spacing distance between adjacent first electrodes in the plurality of first electrodes.
- the present application discloses a filter, which includes the above-mentioned high-frequency acoustic wave resonator.
- the high-frequency acoustic resonator provided by this application has the following beneficial effects:
- the high-frequency acoustic resonator includes a support substrate, a bottom electrode, a piezoelectric film and an interdigital transducer stacked in sequence from bottom to top; the interdigital transducer includes a first bus bar and a plurality of first electrodes arranged at intervals.
- the same side of the plurality of first electrodes is connected to the first bus bar; the product of the spacing distance between the centers of adjacent first electrodes in the plurality of first electrodes and the frequency of the target mode is less than the frequency of the support substrate
- the speed of sound; the target mode is a high-order mode excited by the high-frequency acoustic resonator under the action of a longitudinal electric field; the acoustic resonator provided by this application does not include a Bragg reflective layer, thereby reducing the processing difficulty and the parasitic effects produced by the Bragg reflective layer , the overall structure is simple and the piezoelectric film has high strength, which can still ensure the quality of the acoustic resonator.
- Figure 1 is a schematic structural diagram of an optional acoustic resonator in this application.
- Figure 2 is a partial schematic diagram of an optional acoustic resonator in this application.
- Figure 3 shows a BAW resonator with a Bragg reflective layer
- Figure 4 is the simulated admittance curve of the structure in Figure 3;
- Figure 5 is the vibration shape diagram corresponding to the structure in Figure 3;
- Figure 6 shows an SH1 mode resonator with a Bragg reflective layer
- Figure 7 is the simulated admittance curve of the structure in Figure 6;
- Figure 8 is the vibration shape diagram corresponding to the structure in Figure 6;
- Figure 9 shows a BAW resonator without a Bragg reflective layer
- Figure 10 is the simulated admittance curve of the structure in Figure 9;
- Figure 11 is the vibration shape diagram corresponding to the structure in Figure 9;
- Figure 12 shows an SH1 mode resonator without a Bragg reflective layer
- Figure 13 is the simulated admittance curve of the structure in Figure 12;
- Figure 14 is the vibration shape diagram corresponding to the structure in Figure 12;
- Figure 15 is the admittance curve corresponding to the resonator with different numbers of interdigital electrode pairs designed based on the resonator structure of Figure 12;
- Figure 16 is a vibration shape diagram corresponding to a resonator with different numbers of interdigital electrode pairs designed based on the resonator structure of Figure 12;
- Figure 17 is the admittance curve of an optional resonator in this application.
- Figure 18 is a vibration shape diagram of an optional resonator in this application.
- Figure 19 is the admittance curve of another optional resonator in this application.
- Figure 20 is a vibration shape diagram of another optional resonator in this application.
- references herein to "one embodiment” or “an embodiment” refers to a particular feature, structure, or characteristic that may be included in at least one implementation of the present application.
- the orientation or positional relationship indicated by the terms “upper”, “lower”, “top”, “bottom”, etc. are based on the orientation or positional relationship shown in the drawings and are only for the purpose of To facilitate the description of the present application and to simplify the description, it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present application.
- first and second are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, the characteristics that are limited to “first” and “second” can be One or more of these features are included explicitly or implicitly.
- first”, second, etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances so that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein.
- ranges When a numerical range is disclosed herein, such range is deemed to be continuous and includes the minimum and maximum values of the range, and every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum value and the maximum value of the range is included. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein. For example, a specified range from "1 to 10" shall be deemed to include any and all subranges between the minimum value of 1 and the maximum value of 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.
- resonators in the prior art include a Bragg reflection layer and a sandwich piezoelectric film structure located on it.
- the top electrode on the piezoelectric film layer is a sheet electrode.
- the clutter excited by the longitudinal electric field is difficult to adjust.
- the thickness of the electrode, the thickness of the piezoelectric film, etc. are eliminated, and the Bragg reflective layer process is highly complex.
- Metal is usually used as a high acoustic impedance layer. Even if a patterned bottom electrode is used, the Bragg reflective layer cannot avoid introducing additional parasitic effects. Therefore, how to simplify the structure while retaining the advantages of high-order modes excited by longitudinal fields has become the key to realizing high-frequency and large-bandwidth applications. To this end, refer to Figures 1-2.
- FIG. 1 is a schematic structural diagram of an optional acoustic resonator in this application.
- Figure 2 is a partial schematic diagram of an optional acoustic resonator in this application.
- This application discloses a high-frequency acoustic resonator, which includes a support substrate 1, a bottom electrode 2, a piezoelectric film 3 and an interdigital transducer 4 that are stacked sequentially from bottom to top; the interdigital transducer 4 includes a A bus bar 41 and a plurality of spaced apart first electrodes 42; the same side of the plurality of first electrodes 42 is connected to the first bus bar 41; the adjacent first electrodes 42 in the plurality of first electrodes 42 are The product of the separation distance and the frequency of the target mode is less than the sound speed of the support substrate 1; the target mode is a high-order mode excited by the high-frequency acoustic resonator under the action of an electric field.
- the acoustic resonator provided by this application does not consist of a high acoustic impedance layer.
- the Bragg reflection layer structure or the cavity structure that suspends the piezoelectric film is simple and stable, and ensures that the acoustic wave energy generated by the resonator under electric field excitation can be confined within the piezoelectric film 3 without leaking to the substrate. , ensuring the sonic quality of the resonator.
- the target mode is longitudinal electric field excitation, and the vibration component is mainly in the thickness direction. The electrode coverage rate and the number of electrode pairs have little impact on the target mode, which reduces the photolithography accuracy requirements and improves the flexibility of capacitance control and filter design.
- the resonant frequency of the target mode is determined by the thickness of the piezoelectric film 3, the bulk acoustic wave speed of the piezoelectric film 3, the type of load, and the thickness of the load; the load includes the interdigitated fingers.
- Transducer 4; the phase velocity of the target mode along the first direction (x-axis direction in Figure 2) is determined by the period of the interdigital transducer 4 and the resonant frequency, and the phase velocity in the first direction Greater than or equal to 5000 meters/second; the period of the interdigital transducer 4 is the spacing distance between adjacent first electrodes 42 in the plurality of first electrodes 42; the first direction is parallel to the surface of the piezoelectric film 3 direction.
- the interdigital transducer 4 also includes a second bus bar 43 and a plurality of second electrodes 44 arranged at intervals.
- the plurality of first electrodes 42 and the plurality of second electrodes 44 are arranged at staggered intervals. And the distance between adjacent second electrodes 44 is equal to the distance between adjacent first electrodes 42 .
- the interdigital transducer 4 and the bottom electrode 2 can be a single-layer metal film, a multi-layer metal film, or a composite film composed of metal and non-metal.
- the material of the above-mentioned metal film can be a pure metal material, an alloy, or a material doped with non-metallic elements.
- the type of load may refer to the material type of the load, or may refer to the structural composition of the load.
- the load includes stacked interdigital transducers 4 and an insulating layer.
- the insulating layer can be laid flat on the entire surface of the interdigital transducer 4 , or can be a patterned insulating layer, that is, it can be located only on the bus bars and electrodes of the interdigital transducer 4 .
- the material of the insulating layer may be silicon oxide, aluminum nitride, silicon nitride and other insulating materials.
- the load is the interdigital transducer 4
- the resonant frequency of the resonator decreases; as the elastic coefficient of the material of the interdigital transducer 4 increases, As the thickness of the interdigital transducer 4 increases, the resonant frequency of the resonator decreases.
- the load may also include an interdigital transducer 4 and a metal layer located on it.
- the metal layer is only located on the bus bars and electrodes of the interdigital transducer 4 and cannot cause a short circuit of the interdigital transducer 4 .
- the wave mode corresponding to the target mode is one of a high-order Lamb wave, a high-order horizontal shear wave, and a high-order Rayleigh mode.
- the slow shear wave sound speed in the second direction (x-axis direction in Figure 2) in the support substrate 1 is greater than the phase velocity of the target mode along the first direction; the third The two directions are parallel to the first direction and perpendicular to the first electrode 42 .
- the interdigital transducer 4 and the bottom electrode 2 are prevented from exciting the bulk acoustic wave mode in the overlapping area and becoming a loss source leaking to the supporting substrate 1 .
- the bus bar of the interdigital transducer of the acoustic resonator provided by this application does not have an overlapping area with the bottom electrode 2.
- the bottom electrode 2 is provided with a second through hole corresponding to the first bus bar 41;
- the bottom electrode 2 can be patterned so that there is a preset gap between the sides of the bottom electrode 2 and adjacent bus bars.
- the acoustic resonator further includes an insulating member; a third through hole is provided on the piezoelectric film 3; the third through hole corresponds to the first bus bar 41, and the third through hole
- the insulating member is provided inside; the material of the insulating member is a non-piezoelectric insulating material; that is to say, the piezoelectric film 3 in the orthographic projection area of the bus bar of the interdigital transducer 4 on the piezoelectric film 3 is removed , and fill it with this insulating piece.
- the third through hole may not be filled, as long as there is no overlapping area between the bottom electrode 2 and the bus bar.
- the acoustic resonator in order to improve the quality of the piezoelectric film 3 of the acoustic resonator in the process of preparing the acoustic resonator and avoid holes or fragmentation during the bonding process, is It also includes a bonding layer; the bonding layer is located between the support substrate 1 and the bottom electrode 2; the bonding layer includes non-metallic materials and metallic materials.
- the bonding layer can be titanium or silicon oxide.
- the bonding layer is titanium
- the bonding layer and the bottom electrode 2 are both made of the same material, that is, metal material, in order to avoid the layer structure formed by the two and the interdigital transducer 4
- the bus bars have overlapping areas, thereby reducing the Q value of the device; the bonding layer is provided with a first through hole corresponding to the second through hole; or the piezoelectric film 3 can also be patterned as described above.
- the bonding layer does not need to be provided with a first through hole; in order to further simplify the structure,
- the bonding layer and the bottom electrode 2 can be the same layer, that is, the same material.
- the acoustic wave resonator also includes a low-speed dielectric layer 8; the low-speed dielectric layer 8 is located between the support substrate 1 and the bottom electrode 2; the material of the low-speed dielectric layer 8 includes metallic materials and non-metallic materials, such as : Silicon oxide, gold, platinum, etc.
- the low sound velocity dielectric layer 8 and the bonding layer may be the same layer, for example, when the materials of the low sound velocity dielectric layer 8 and the bonding layer are both silicon oxide; optionally, the low sound velocity dielectric layer 8 8 and the bonding layer may not be the same layer, then there is a sequentially stacked low-speed dielectric layer 8 and the bonding layer between the support substrate 1 and the bottom electrode 2 of the acoustic resonator.
- the material of the bonding layer may be titanium. , nickel, tungsten, niobium, chromium, silicon oxide, benzocyclobutene (BCB), etc.; the material of the low sound velocity layer can be silicon oxide, gold, platinum, etc.
- the low-sound velocity dielectric layer 8 and the bonding layer exist at the same time, and both are made of metal materials, in order to further improve the acoustic wave quality of the resonator, it is necessary to avoid the overlapping area between the interdigital transducer 4 and the bottom electrode 2
- the bulk acoustic wave mode is excited and becomes a loss source leaking to the supporting substrate 1 .
- the low-speed dielectric layer 8 and the bonding layer can be patterned.
- the acoustic resonator only has the low-speed dielectric layer 8, but its If it is a metal material, it can also be patterned according to the above-mentioned treatment method when the bonding layer is titanium.
- the support substrate 1 includes a stacked first substrate and a high-sonic velocity substrate; the material of the first substrate is a material that is easy to form and process; the material of the high-sonic velocity substrate is silicon carbide of different crystal forms and different cuts. , diamond, diamond-like diamond, sapphire, aluminum nitride and silicon nitride.
- the support substrate 1 may also be the above-mentioned high-sonic velocity substrate as needed.
- the supporting substrate has a two-layer structure, that is, it includes a stacked first substrate and a high-sonic-velocity substrate
- the high-sonic-velocity substrate can be grown through epitaxial growth or physical vapor deposition (Physical Vapor Deposition, PVD) or other processes.
- the bottom material is deposited on the first substrate.
- the thickness of the high-sonic-velocity substrate is on the order of microns, thereby forming a high-sonic-velocity substrate. Because when the supporting substrate has a two-layer structure, the thickness of the high-sound-velocity supporting substrate is thin, in order to effectively confine the sound wave within the piezoelectric film and prevent it from spreading to the substrate.
- the thickness of the high-sonic velocity substrate is greater than or equal to 0.5 times the spacing distance between adjacent first electrodes 42 among the plurality of first electrodes 42 . That is, the thickness of the high-sonic velocity substrate is greater than or equal to 0.5 times the period of the interdigital transducer 4 .
- the target mode is excited by the longitudinal electric field; the electrode coverage, the period of the interdigital transducer 4 and the in-plane propagation direction have little impact on the target mode, and can be achieved by utilizing the differences in dispersion effects of different modes and material anisotropy. to suppress clutter.
- each layer such as piezoelectric film, interdigital transducer, bottom electrode, etc.
- Changes in resonant frequency is caused by adjusting the ratio of the thickness of each layer (such as piezoelectric film, interdigital transducer, bottom electrode, etc.) to the period of the interdigital transducer. Changes in resonant frequency.
- a BAW resonator with a Bragg reflection layer 5 is provided.
- Figure 3 is a BAW resonator with a Bragg reflection layer
- Figure 4 is a simulated admittance curve of the structure of Figure 3
- Figure 5 is the corresponding structure of Figure 3 vibration shape diagram.
- the piezoelectric film 3 of this BAW resonator is an X-cut lithium niobate film
- the support substrate 1 is a silicon substrate
- the Bragg reflection layer 5 is a structure of 295nm silicon oxide/80nm platinum repeated three times alternately, and the resonator in Figure 4
- the thicknesses of the piezoelectric films 3 in the first and second resonators are 325nm and 230nm respectively.
- the piezoelectric film 3 is provided with a sheet-shaped top electrode 6.
- the target mode corresponding to the BAW resonator is TSM.
- the vibration shape diagram shown in Figure 5 corresponds to the resonance peak of the dotted line ring in Figure 4. It can be seen from the vibration shape diagram in Figure 5 that due to the reflection of acoustic wave energy formed by the Bragg reflection layer 5, its vibrations are concentrated on the surface of the support substrate 1 , X-cut lithium niobate has the phenomenon of two shear waves coupling with each other, namely fast shear waves and slow shear waves.
- the sandwich structure BAW resonator cannot achieve decoupling of the two modes.
- an SH1 mode resonator with a Bragg reflection layer 5 is provided.
- Figure 6-8 Figure 6 is a SH1 mode resonator with a Bragg reflection layer;
- Figure 7 is a simulated admittance curve of the structure in Figure 6;
- Figure 8 is a vibration shape diagram corresponding to the structure in Figure 6.
- the piezoelectric film 3 of the SH1 mode resonator is an X-cut lithium niobate film
- the support substrate 1 is a silicon substrate
- the Bragg reflection layer 5 is a structure of 295nm silicon oxide/80nm platinum repeated three times alternately
- the resonator in Figure 7 The thicknesses of the piezoelectric films 3 in the first and second resonators are 325nm and 230nm respectively.
- the piezoelectric film 3 is provided with interdigital electrodes 7.
- the target mode corresponding to the resonator shown in Figure 6 is SH1.
- the vibration shape diagram shown in Figure 8 corresponds to the resonance peak of the dotted line ring in Figure 6.
- the vibration shape diagrams in Figure 5 and Figure 8 it can be seen that due to the reflection of acoustic wave energy formed by the Bragg reflection layer 5, whether it is the TSM mode or the SH1 mode , the vibrations are concentrated on the surface of the supporting substrate 1.
- the wavelength of the resonator 1 in Figure 7 is 1.65 microns, and the corresponding Euler angle of lithium niobate is (24, 90, -90),
- the wavelength of the second resonator in Figure 7 is 1.603 microns, and the Euler angle of lithium niobate is (27, 90, -90).
- the suppression of clutter is achieved by selecting the appropriate film in-plane orientation and electrode thickness.
- the high-order mode resonator having the bottom electrode 2 and the interdigital top electrode 7 has the advantage of suppressing clutter. That is to say, based on the clutter suppression principle of this application, by designing the piezoelectric film 3 and electrode structure of the resonator with the Bragg reflection layer 5, the effect of suppressing clutter can be achieved. It can also be demonstrated that based on the bottom electrode 2 The high-order mode resonator with the interdigital top electrode 7 has the advantage of suppressing clutter.
- a BAW resonator without a Bragg reflection layer 5 is first provided. Refer to Figure 9-11.
- Figure 9 is a BAW resonator without a Bragg reflection layer;
- Figure 10 is a simulated admittance curve of the structure in Figure 9;
- Figure 11 is a vibration shape diagram corresponding to the structure in Figure 9.
- the piezoelectric film 3 of the BAW resonator shown in Figure 9 is an The thicknesses of the piezoelectric films 3 in are 325nm and 230nm respectively. As can be seen from Figure 9, the piezoelectric film 3 is provided with a sheet-shaped top electrode 6.
- the corresponding target mode in the BAW resonator of Figure 9 is TSM.
- the vibration shape diagram shown in Figure 11 corresponds to the resonance peak of the dotted line ring in Figure 10. It can be seen from the vibration shape diagram in Figure 11 that a large amount of acoustic wave energy in the TSM mode leaks deep into the substrate, which also results in its quality factor Q has dropped significantly, and the admittance ratio of the corresponding admittance curve has been reduced to 30dB, which is no longer able to meet actual needs.
- FIG. 12 is a SH1 mode resonator without a Bragg reflection layer
- Figure 13 is a simulated admittance curve of the structure in Figure 12
- Figure 14 is a vibration shape diagram corresponding to the structure in Figure 12.
- Figure 12 Piezoelectric of SH1 mode resonator Film 3 is an For 325nm, 230nm. As can be seen from Figure 12, the piezoelectric film 3 is provided with interdigitated top electrodes 7. The corresponding mode in the SH1 mode resonator of Figure 12 is SH1.
- the wavelength of resonator one in Figure 13 is 1.65 microns
- the corresponding Euler angle of lithium niobate is (24, 90, -90)
- the wavelength of resonator two in Figure 13 is 1.603 microns.
- the Euler angle of lithium niobate is (27, 90, -90);
- the vibration shape diagram shown in Figure 14 corresponds to the resonance peak of the dotted line ring in Figure 13.
- the SH1 mode resonator corresponding to Figure 14 not only suppresses clutter, but also achieves good energy confinement in a substrate with a simple structure.
- the effective electromechanical coupling coefficients of resonator one and resonator two of the SH1 mode resonator are 49.6% and 53.6% respectively, which can meet the bandwidth requirements of all frequency bands below 6GHz.
- Figure 15 shows the corresponding admittance curves of resonators with different numbers of interdigital electrode pairs designed based on the resonator structure of Figure 12. Among them, the number of interdigital electrode pairs corresponding to curve a in Figure 15 is 60 pairs, the number of interdigital electrode pairs corresponding to curve b is 20 pairs, and the number of interdigital electrode pairs corresponding to curve a is 10 pairs. Refer to Figure 2.
- the counter-interdigital electrode includes a first electrode 42 and a second electrode 44. It can be seen from Figure 15 that the shape of the admittance curve of the SH1 mode resonator with a simplified structure is basically not affected by the reduction in the number of electrode pairs. When the number of electrode pairs is reduced from 60 pairs to 10 pairs, the admittance ratio almost changes.
- Figure 16 is a vibration shape diagram corresponding to a resonator with different numbers of interdigital electrode pairs designed based on the resonator structure of Figure 12. Among them, the numbers of electrode pairs corresponding to pictures (a), (b) and (c) in Figure 16 are 60 pairs, 20 pairs and 10 pairs respectively. It can be seen from Figure 16 that different numbers of electrode pairs correspond to anti-resonance.
- the frequency mode pattern surface decreases with the electrode, and the vibration is still well localized on the substrate surface.
- the capacitance of the resonator of this structure is proportional to the number of interdigital electrode pairs, and the device performance is hardly affected by the number of electrodes. Therefore, the capacitance can be flexibly adjusted, which greatly improves the flexibility of filter design.
- This embodiment provides a resonator.
- the structure of the resonator is as shown in Figure 1.
- the material of the supporting substrate 1 is sapphire, the corresponding Euler angle is (44.5,125,0), and the piezoelectric film 3 is x Cut niobic acid Lithium, the corresponding wavelength is 1.6 microns, and the target mode is SH1 mode.
- the corresponding admittance curve and vibration shape diagram of this resonator are shown in Figure 17 and Figure 18 respectively. It should be noted that the vibration shape diagram shown in Figure 18 corresponds to the resonance peak of the dotted line ring in Figure 17. It can be seen that the vibration Mainly concentrated on the surface of the substrate, its effective electromechanical coupling coefficient is 50.5%, which also meets the bandwidth requirements of all frequency bands below 6GHz.
- This embodiment provides another resonator.
- the structure of the resonator is as shown in Figure 1.
- the material of the supporting substrate 1 is a 6H-SiC substrate.
- the piezoelectric film 3 is Y36 cut lithium niobate.
- the piezoelectric film The thickness of 3 is 312 nanometers, the wavelength is 1.2 microns, and the target mode is a high-order symmetric Lamb wave mode (S1).
- S1 high-order symmetric Lamb wave mode
- the corresponding admittance curve and vibration shape diagram of this resonator are shown in Figure 19 and Figure 20 respectively. It should be noted that the vibration shape diagram shown in Figure 20 corresponds to the resonance peak of the dotted line ring in Figure 19.
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Abstract
本发明涉及微电子技术领域,本发明公开了一种高频声波谐振器及应用其的滤波器。该高频声波谐振器包括由下至上依次层叠的支撑衬底、底电极、压电薄膜和叉指换能器;该叉指换能器包括第一汇流条和多个间隔设置的第一电极;该多个第一电极的同一侧与该第一汇流条连接;该多个第一电极中相邻的第一电极的中心之间的间隔距离与目标模式的频率之积小于该支撑衬底的声速;该目标模式为该高频声波谐振器在纵向电场作用下激发的高阶模式;本申请提供的该声波谐振器建立在异质集成衬底上,具有结构简单且压电薄膜强度高,仍能够保证声波谐振器的品质的特点。
Description
本发明涉及微电子技术领域,特别涉及一种高频声波谐振器及应用其的滤波器。
现代通讯行业对信号质量的要求越来越高以及对通信频谱资源的争夺越演越烈。低损耗、宽带宽、可调谐以及温度稳定性已经成为通讯行业的普遍追求目标。声学谐振器包括声表面波(Surface Acoustic Wave,SAW)谐振器和体声波(Bulk Acoustic Wave,BAW);谐振器因其体积小、带宽大、Q值高目前已经广泛应用于通信领域。其中BAW谐振器由于谐振频率与厚度成反比,通过对薄膜减薄可以轻松实现较高的频率。
然而,随着频率的提高,悬空的压电薄膜逐渐变薄,结构变得更加脆弱且散热变得更加艰难。且传统的固态装配型体声波谐振器(BAW-SMR)为了获得高Q值的谐振器,利用多层布拉格反射层结构来将声波能量局限在压电薄膜内,但这大大提高了工艺难度和生产成本。
发明内容
为解决上述现有技术中高频声波谐振器工艺难度大和结构复杂的技术问题,本申请于一方面公开了一种高频声波谐振器,其包括由下至上依次层叠的支撑衬底、底电极、压电薄膜和叉指换能器;
该叉指换能器包括第一汇流条和多个间隔设置的第一电极;该多个第一电极的同一侧与该第一汇流条连接;
该多个第一电极中相邻的第一电极的中心之间间隔距离与目标模式的频率之积小于该支撑衬底的声速;该目标模式为该高频声波谐振器在纵向电场作用下激发的高阶模式。
可选的,该目标模式的谐振频率由该压电薄膜的厚度、该压电薄膜的体声波声速、负载的类型和该负载的厚度决定;该负载包括该叉指换能器;
该目标模式的沿第一方向的相速度由该叉指换能器的周期和该谐振频率决定,且该第一方向的相速度大于等于5000米/秒;该叉指换能器的周期为该多个第一电极中相邻的第一电极的中心之间的间隔距离;该第一方向为平行于该压电薄膜的表面的方向。
可选的,该目标模式对应的波型为高阶兰姆波、高阶水平剪切波以及高阶瑞利模式中的一种。
可选的,该支撑衬底中在第二方向的慢剪切波声速大于该目标模式的沿第一方向的相速度;该第二方向为与该第一方向平行,且垂直于该第一电极的方向。
可选的,该第一汇流条的第一侧边与邻近的底电极的侧边存在预设距离;该第一侧边为靠近该底电极的侧边。
可选的,还包括绝缘件;
压电薄膜上设有第一通孔;
第一通孔与第一汇流条对应,且所述第一通孔内设有该绝缘件;
该绝缘件的材料为非压电的绝缘材料。
可选的,还包括键合层;
该键合层位于该支撑衬底与该底电极之间;
该键合层包括非金属材料和金属材料。
可选的,还包括低声速介质层;
所述低声速介质层位于所述支撑衬底与所述底电极之间;
所述低声速介质层包括非金属材料和金属材料。
可选的,该支撑衬底包括层叠的第一衬底和高声速衬底;
该第一衬底的材料为易成型加工的材料;
该高声速衬底的材料为不同晶型及不同切型的碳化硅、金刚石、类金刚石、蓝宝石、氮化铝和氮化硅中的一种。
可选的,该高声速衬底的厚度大于等于0.5倍的该多个第一电极中相邻的第一电极的间隔距离。
本申请于另一方面公开了一种滤波器,其包括上述的高频声波谐振器。
采用上述技术方案,本申请提供的高频声波谐振器具有如下有益效果:
该高频声波谐振器包括由下至上依次层叠的支撑衬底、底电极、压电薄膜和叉指换能器;该叉指换能器包括第一汇流条和多个间隔设置的第一电极;该多个第一电极的同一侧与该第一汇流条连接;该多个第一电极中相邻的第一电极的中心之间间隔距离与目标模式的频率之积小于该支撑衬底的声速;该目标模式为该高频声波谐振器在纵向电场作用下激发的高阶模式;本申请提供的该声波谐振器不包括布拉格反射层,从而可以降低加工难度和布拉格反射层产生的寄生效应,整体具有结构简单且压电薄膜强度高,仍能够保证声波谐振器的品质的特点。
为了更清楚地说明本申请实施例中的技术方案,下面将对实施例描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图仅仅是本申请的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他的附图。
图1为本申请一种可选的声波谐振器的结构示意图;
图2为本申请一种可选的声波谐振器的局部示意图;
图3为具有布拉格反射层的BAW谐振器;
图4为图3结构的仿真导纳曲线;
图5为图3结构对应的振型图;
图6为具有布拉格反射层的SH1模式谐振器;
图7为图6结构的仿真导纳曲线;
图8为图6结构对应的振型图;
图9为不具有布拉格反射层的BAW谐振器;
图10为图9结构的仿真导纳曲线;
图11为图9结构对应的振型图;
图12为不具有布拉格反射层的SH1模式谐振器;
图13为图12结构的仿真导纳曲线;
图14为图12结构对应的振型图;
图15为基于图12结构的谐振器设计的不同叉指电极对数的谐振器对应的导纳曲线;
图16为基于图12结构的谐振器设计的不同叉指电极对数的谐振器对应的振型图;
图17为本申请一种可选的谐振器的导纳曲线;
图18为本申请一种可选的谐振器的振型图;
图19为本申请另一种可选的谐振器的导纳曲线;
图20为本申请另一种可选的谐振器的振型图。
以下对附图作补充说明:
1-支撑衬底;2-底电极;3-压电薄膜;4-叉指换能器;41-第一汇流条;
42-第一电极;43-第二汇流条;44-第二电极;5-布拉格反射层;6-片状顶电极;7-叉指顶电极;8-低声速介质层。
1-支撑衬底;2-底电极;3-压电薄膜;4-叉指换能器;41-第一汇流条;
42-第一电极;43-第二汇流条;44-第二电极;5-布拉格反射层;6-片状顶电极;7-叉指顶电极;8-低声速介质层。
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清楚、完整地描述。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。基于本申请中的实施例,本领域普通技术人员在没有作出创造性劳动的前提下所获得的所有其他实施例,都属于本申请保护的范围。
此处所称的“一个实施例”或“实施例”是指可包含于本申请至少一个实现方式中的特定特征、结构或特性。在本申请的描述中,需要理解的是,术语“上”、“下”、“顶”、“底”等指示的方位或位置关系为基于附图所示的方位或位置关系,仅是为了便于描述本申请和简化描述,而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作,因此不能理解为对本申请的限制。此外,术语“第一”、“第二”仅用于描述目的,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“第一”、“第二”的特征可以
明示或者隐含的包括一个或者更多个该特征。而且,术语“第一”、“第二”等是用于区别类似的对象,而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换,以便这里描述的本申请的实施例能够以除了在这里图示或描述的那些以外的顺序实施。
尽管阐述本发明的广泛范围的数值范围和参数是近似值,但是具体实例中列出的数值尽可能精确地报告。然而,任何数值固有地包含由其各自测试测量中发现的标准偏差必然产生的某些误差。
当本文中公开一个数值范围时,上述范围视为连续,且包括该范围的最小值及最大值,以及这种最小值与最大值之间的每一个值。进一步地,当范围是指整数时,包括该范围的最小值与最大值之间的每一个整数。此外,当提供多个范围描述特征或特性时,可以合并该范围。换言之,除非另有指明,否则本文中所公开之所有范围应理解为包括其中所归入的任何及所有的子范围。例如,从“1至10”的指定范围应视为包括最小值1与最大值10之间的任何及所有的子范围。范围1至10的示例性子范围包括但不限于1至6.1、3.5至7.8、5.5至10等。
通常,现有技术中的谐振器包括布拉格反射层和位于其上的三明治压电薄膜结构,压电薄膜层上的顶电极为片状电极,该种结构在纵向电场激发的杂波难以通过调整电极的厚度、压电薄膜的厚度等来消除,且布拉格反射层工艺复杂度高,通常采用金属作为高声阻抗层,即使采用图案化底电极也无法避免布拉格反射层引入额外寄生效应。因此,如何简化结构,同时保留纵向场激发的高阶模态的优点,成为其实现高频大带宽应用的关键。为此,参阅图1-2,图1为本申请一种可选的声波谐振器的结构示意图。图2为本申请一种可选的声波谐振器的局部示意图。本申请公开了一种高频声波谐振器,其包括由下至上依次层叠的支撑衬底1、底电极2、压电薄膜3和叉指换能器4;该叉指换能器4包括第一汇流条41和多个间隔设置的第一电极42;该多个第一电极42的同一侧与该第一汇流条41连接;该多个第一电极42中相邻的第一电极42的间隔距离与目标模式的频率之积小于该支撑衬底1的声速;该目标模式为该高频声波谐振器在电场作用下激发的高阶模式。本申请提供的该声波谐振器不存在由高低声阻抗层组成
的布拉格反射层结构或使压电薄膜悬空的空腔结构,结构简单且稳定,且保证该谐振器在电场激发下生成的声波能量能够局限在压电薄膜3内,而不会泄露到衬底中,保证谐振器的声波品质。除了金属电极以外无其他导电材料,避免了布拉格反射层引入额外寄生效应。目标模式为纵向电场激励,振动分量以厚度方向为主,电极覆盖率以及电极对数对目标模式影响不大,降低了光刻精度要求,提高了电容调控和滤波器设计的灵活度。
于一种可行的实施例中,该目标模式的谐振频率由该压电薄膜3的厚度、该压电薄膜3的体声波声速、负载的类型和该负载的厚度决定;该负载包括该叉指换能器4;该目标模式的沿第一方向(如图2中的x轴方向)的相速度由该叉指换能器4的周期和该谐振频率决定,且该第一方向的相速度大于等于5000米/秒;该叉指换能器4的周期为该多个第一电极42中相邻的第一电极42的间隔距离;该第一方向为平行于该压电薄膜3的表面的方向。
可选的,参阅图2,该叉指换能器4还包括第二汇流条43和多个间隔排列的第二电极44,多个第一电极42与多个第二电极44交错间隔排列,且相邻的第二电极44的距离等于相邻的第一电极42的距离。
可选的,该叉指换能器4和底电极2可以是单层金属薄膜、多层金属薄膜、金属与非金属组成的复合薄膜。可选的,上述金属薄膜的材料可以是纯金属材料、合金、掺杂非金属元素的材料。
可选的,负载的类型可以是指负载的材料种类,还可以是指负载的结构组成,例如,负载包括层叠的叉指换能器4和绝缘层。
可选的,该绝缘层可以整面平铺在该叉指换能器4的表面,还可以是图案化的绝缘层,即仅位于叉指换能器4的汇流条和电极上。
可选的,该绝缘层的材料可以是氧化硅、氮化铝、氮化硅等绝缘材料。
可选的,当负载为叉指换能器4时,随着叉指换能器4的材料的密度上升,该谐振器的谐振频率下降;随着叉指换能器4的材料的弹性系数上升,该谐振器的谐振频率上升;随着叉指换能器4的厚度增加,该谐振器的谐振频率下降。
可选的,该负载还可以包括叉指换能器4和位于其上的金属层,该金
属层仅位于叉指换能器4的汇流条和电极上,不能造成叉指换能器4短路。
于一种可行的实施例中,该目标模式对应的波型为高阶兰姆波、高阶水平剪切波以及高阶瑞利模式中的一种。
于一种可行的实施例中,该支撑衬底1中在第二方向(如图2中的x轴方向)的慢剪切波声速大于该目标模式的沿第一方向的相速度;该第二方向为与该第一方向平行,且垂直于该第一电极42的方向。
于一种可行的实施例中,为了进一步提高该谐振器的声波品质,避免叉指换能器4与底电极2在重叠区域激发出体声波模式,成为向支撑衬底1泄露的损耗源。本申请提供的该声波谐振器的叉指换能器的汇流条与底电极2不存在重叠区域,可选的,该底电极2设有与该第一汇流条41对应的第二通孔;可选的,如图2所示,该第一汇流条41的第一侧边与邻近的底电极2的侧边存在预设距离;该第一侧边为靠近该底电极2的侧边。也就是说,可以通过图案化底电极2,以使底电极2的侧边与相邻的汇流条之间存在预设间隙。于另一种可行的实施例中,该声波谐振器还包括绝缘件;压电薄膜3上设有第三通孔;第三通孔与第一汇流条41对应,且所述第三通孔内设有该绝缘件;该绝缘件的材料为非压电的绝缘材料;也就是说,叉指换能器4的汇流条在压电薄膜3上的正投影区域的压电薄膜3被去除,并用该绝缘件填充。当然,也可以不对第三通孔进行填充,只要保证底电极2与汇流条不存在重叠区域即可。
于一种可行的实施例中,为了提高在制备该声波谐振器的过程中,提高声波谐振器的压电薄膜3的质量,避免键合过程中存在孔洞或者碎裂的情况,该声波谐振器还包括键合层;该键合层位于该支撑衬底1与该底电极2之间;该键合层包括非金属材料和金属材料,例如,该键合层可以是钛或者氧化硅。
于一种可行的实施例中,当键合层为钛,由于键合层与底电极2均为同一类材料,即金属材料,同样为了避免二者形成的层结构与叉指换能器4的汇流条存在重叠区域,进而降低器件的Q值;该键合层上设有与该第二通孔对应的第一通孔;或者还可以是如上述对压电薄膜3进行图案化处理的方式,该键合层则不需要设置第一通孔;为了在进一步简化结构同时,
提高声波谐振器的质量,可选的,该键合层与底电极2可以是同一层,即为同一种材料。
于一种可行的实施例中,为了提高该声波谐振器的能量反射效率,并提高机电耦合系数。该声波谐振器还包括低声速介质层8;该低声速介质层8位于支撑衬底1与底电极2之间;该低声速介质层8的材料包括金属材料和非金属材料,例如:氧化硅、金、铂等。
可选的,该低声速介质层8与键合层可以是同一层,例如当低声速介质层8和键合层的材料均为氧化硅时;可选的,该低声速介质层8与键合层可以不是同一层,则该声波谐振器的支撑衬底1与底电极2之间设有依次层叠的低声速介质层8和键合层,键合层的材料可以是钛、镍、钨、铌、铬、氧化硅、苯丙环丁烯(BCB)等;低声速层的材料可以是氧化硅、金、铂等。
需要说明的是,当低声速介质层8和键合层同时存在,且均为金属材料时,为了进一步提高该谐振器的声波品质,避免叉指换能器4与底电极2在重叠区域激发出体声波模式,成为向支撑衬底1泄露的损耗源。该低声速介质层8与键合层可以进行图案化处理,详见上述对键合层为钛时的处理方式,同理,当该声波谐振器仅具有低声速介质层8,但其为金属材料,也可以按照上述对键合层为钛时的处理方式进行图案化处理。
于一种可行的实施例中,为了提高该声波谐振器在成型加工过程中的可加工性。该支撑衬底1包括层叠的第一衬底和高声速衬底;该第一衬底的材料为易成型加工的材料;该高声速衬底的材料为不同晶型及不同切型的碳化硅、金刚石、类金刚石、蓝宝石、氮化铝和氮化硅中的一种。可选的,根据需要,该支撑衬底1也可以为上述高声速衬底。
需要说明的是,当该支撑衬底为两层结构,即包括层叠的第一衬底和高声速衬底,可以通过外延生长或者物理气相沉积(Physical Vapor Deposition,PVD)等工艺将高声速衬底的材料沉积到第一衬底上,一般,该高声速衬底的厚度为微米级,从而形成高声速衬底。由于当该支撑衬底为两层结构时,高声速支撑衬底的厚度较薄,为了有效将声波限制在压电薄膜内,避免其向衬底扩散。可选的,该高声速衬底的厚度大于等于0.5
倍的该多个第一电极42中相邻的第一电极42的间隔距离。即,该高声速衬底的厚度大于等于0.5倍的叉指换能器4的周期。
可选的,目标模式由纵向电场激励;电极覆盖率,叉指换能器4的周期以及面内传播方向对目标模式影响较小,可以通过利用不同模式的频散效应差异和材料各向异性来抑制杂波。
需要说明的是,不同模式的频散效应差异是指通过调整每一层厚度(例如压电薄膜,叉指换能器,底电极等)与叉指换能器的周期的比值变化带来的谐振频率的变化。
为了便于理解本申请的技术方案以及说明本申请的有益效果,以下将以具体实施例进行阐述。
下面先对下文涉及的名词简称进行说明。
SH1:First-order shear horizontal mode一阶水平剪切模式
S1:First-order symmetric Lamb wave mode一阶对称型兰姆波模式
BAW:Bulk Acoustic Wave体声波
TSM:Thickness Shear Mode厚度剪切模式
实施例1
提供一种具有布拉格反射层5的BAW谐振器,参阅图3-5,图3为具有布拉格反射层的BAW谐振器;图4为图3结构的仿真导纳曲线;图5为图3结构对应的振型图。该BAW谐振器的压电薄膜3为X切铌酸锂薄膜,支撑衬底1为硅衬底,布拉格反射层5为295nm氧化硅/80nm铂交替重复三次的结构,且图4中的谐振器一和谐振器二中的压电薄膜3的厚度分别为325nm、230nm。由图3可知,压电薄膜3上设有片状顶电极6。BAW谐振器对应的目标模式为TSM。图5所示的振型图对应图4中虚线环的谐振峰,由图5的振型图可以看出,由于布拉格反射层5形成的声波能量反射,其振动都集中在支撑衬底1表面,X切铌酸锂存在两种剪切波相互耦合的现象,即快剪切波和慢剪切波,三明治结构的BAW谐振器无法实现两种模式的解耦。
为了进一步对比说明本申请的有益效果,提供一种具有布拉格反射层5的SH1模式谐振器。参阅图6-8,图6为具有布拉格反射层的SH1模式谐振器;图7为图6结构的仿真导纳曲线;图8为图6结构对应的振型图。该
SH1模式谐振器的压电薄膜3为X切铌酸锂薄膜,支撑衬底1为硅衬底,布拉格反射层5为295nm氧化硅/80nm铂交替重复三次的结构,且图7中的谐振器一和谐振器二中的压电薄膜3的厚度分别为325nm、230nm。由图6可知,压电薄膜3上设有叉指顶电极7。该图6所示的谐振器对应的目标模式为SH1。图8所示的振型图对应图6中虚线环的谐振峰,对比图5和图8的振型图可以看出,由于布拉格反射层5形成的声波能量反射,无论是TSM模式还是SH1模式,其振动都集中在支撑衬底1表面,对于该SH1模式谐振器,图7中的谐振器一的波长为1.65微米,对应的铌酸锂欧拉角为(24,90,-90),图7中的谐振器二的波长为1.603微米,铌酸锂欧拉角为(27,90,-90),通过选择了合适的薄膜面内取向和电极厚度实现了杂波的抑制,由此可知,具有底电极2和叉指顶电极7的高阶模式谐振器具有抑制杂波的优势。也就是说,基于本申请的杂波抑制原理,通过对具有布拉格反射层5的谐振器进行压电薄膜3和电极结构的设计,可到达抑制杂波的效果,也可论证基于具有底电极2和叉指顶电极7的高阶模式谐振器具有抑制杂波的优势。
为了更好地说明本申请这种不具有布拉格反射层的谐振器结构的有益效果,先提供一不具有布拉格反射层5的BAW谐振器。参阅图9-11,图9为不具有布拉格反射层的BAW谐振器;图10为图9结构的仿真导纳曲线;图11为图9结构对应的振型图。图9的BAW谐振器的压电薄膜3为X切铌酸锂薄膜,支撑衬底1为4H-SiC,低声速介质层8为氧化硅,且图10中的谐振器一和谐振器二中的压电薄膜3的厚度分别为325nm、230nm。由图9可知,压电薄膜3上设有片状顶电极6。图9的BAW谐振器中对应的目标模式为TSM。图11所示的振型图对应图10中虚线环的谐振峰,从图11的振型图中可以看出,TSM模式的声波能量大量泄漏到衬底深处,这也导致其品质因子Q大幅下降,相应导纳曲线的导纳比减小到30dB,已经无法满足实际需求。
提供一不具有布拉格反射层5的SH1模式谐振器。参阅图12-14,图12为不具有布拉格反射层的SH1模式谐振器;图13为图12结构的仿真导纳曲线;图14为图12结构对应的振型图。图12的SH1模式谐振器的压电
薄膜3为X切铌酸锂薄膜,支撑衬底1为4H-SiC,低声速介质层8为氧化硅,且图13中的谐振器一和谐振器二中的压电薄膜3的厚度分别为325nm、230nm。由图12可知,压电薄膜3上设有叉指顶电极7。图12的SH1模式谐振器中对应的模式为SH1。对于该SH1模式谐振器,图13中的谐振器一的波长为1.65微米,对应的铌酸锂欧拉角为(24,90,-90),图13中的谐振器二的波长为1.603微米,铌酸锂欧拉角为(27,90,-90);图14所示的振型图对应图13中虚线环的谐振峰,通过对比图11和图14的振型图,以及图10和图13可以看出,图14对应的SH1模式谐振器不仅杂波得到了抑制,在结构简单的衬底中仍然实现了很好的能量约束。由图13可知,SH1模式谐振器的谐振器一和谐振器二对应的有效机电耦合系数分别为49.6%和53.6%,可以满足6GHz以下所有频段的带宽需求。
传统的BAW谐振器为了抑制水平方向的高阶杂波往往需要较大的电极,而谐振器的电容与电极面积成正比,一方面在高频较难匹配50欧姆终端,一方面大大限制了滤波器设计的灵活性。参阅图15,图15为基于图12结构的谐振器设计的不同叉指电极对数的谐振器对应的导纳曲线。其中,图15中的曲线a对应的叉指电极对数为60对,曲线b对应的叉指电极对数为20对,曲线a对应的叉指电极对数为10对,参阅图2,每对叉指电极包括一个第一电极42和一个第二电极44。由图15可以看出,结构简化的SH1模式谐振器,其导纳曲线的形貌基本不受电极对数减少的影响。电极对数从60对减少到10对时,导纳比几乎变。参阅图16,图16为基于图12结构的谐振器设计的不同叉指电极对数的谐振器对应的振型图。其中,图16中的图(a)、图(b)和图(c)分别对应的电极对数为60对、20对和10对,由图16可以看出,不同电极对数对应反谐振频率的振型图表面随电极减少,振动仍被很好地局限在衬底表面。该结构的谐振器的电容与叉指电极对数成正比,而器件性能几乎不受电极多少的影响,因此可以灵活调节电容,大大提高了滤波器设计的灵活度。
实施例2
本实施例提供一种谐振器,该谐振器的结构为如图1所示,支撑衬底1的材料为蓝宝石,对应的欧拉角为(44.5,125,0),压电薄膜3为x切铌酸
锂,对应的波长为1.6微米,目标模式为SH1模式。该谐振器对应的导纳曲线和振型图分别为图17和图18所示,需要说明的是,图18所示的振型图对应图17中虚线环的谐振峰,可以看出,振动主要集中在衬底表面,其有效机电耦合系数为50.5%,同样满足6GHz以下所有频段的带宽需求。
实施例3
本实施例提供了另一种谐振器,该谐振器的结构为如图1所示,支撑衬底1的材料为6H-SiC衬底,压电薄膜3为Y36切铌酸锂,压电薄膜3的厚度为312纳米,波长为1.2微米,目标模式为高阶对称型兰姆波模式(S1)。该谐振器对应的导纳曲线和振型图分别为图19和图20,需要说明的是,图20所示的振型图对应图19中虚线环的谐振峰,可以看出,由图20可知,振动主要集中在衬底表面,该模式声速更高,因此,可以在压电薄膜3厚度适中的情况下实现高达6GHz的工作频率。如图19所示,其有效机电耦合系数为14.8%,可以满足5G WiFi频段需求。
以上所述仅为本申请可选实施例,并不用以限制本申请,凡在本申请的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本申请的保护范围之内。
Claims (11)
- 一种高频声波谐振器,其特征在于,包括由下至上依次层叠的支撑衬底、底电极、压电薄膜和叉指换能器;所述叉指换能器包括第一汇流条和多个间隔设置的第一电极;所述多个第一电极的同一侧与所述第一汇流条连接;所述多个第一电极中相邻的第一电极的中心之间的间隔距离与目标模式的频率之积小于所述支撑衬底的声速;所述目标模式为所述高频声波谐振器在纵向电场作用下激发的高阶模式。
- 根据权利要求1所述的高频声波谐振器,其特征在于,所述目标模式的谐振频率由所述压电薄膜的厚度、所述压电薄膜的体声波声速、负载的类型和所述负载的厚度决定;所述负载包括所述叉指换能器;所述目标模式的沿第一方向的相速度由所述叉指换能器的周期和所述谐振频率决定,且所述第一方向的相速度大于等于5000米/秒;所述叉指换能器的周期为所述多个第一电极中相邻的第一电极的中心之间的间隔距离;所述第一方向为平行于所述压电薄膜的表面的方向。
- 根据权利要求1所述的高频声波谐振器,其特征在于,所述目标模式对应的波型为高阶兰姆波、高阶水平剪切波以及高阶瑞利模式中的一种。
- 根据权利要求1所述的高频声波谐振器,其特征在于,所述支撑衬底中在第二方向的慢剪切波声速大于所述目标模式的沿第一方向的相速度;所述第二方向为与所述第一方向平行,且垂直于所述第一电极的方向。
- 根据权利要求1所述的高频声波谐振器,其特征在于,所述第一汇流条的第一侧边与邻近的底电极的侧边存在预设距离;所述第一侧边为靠近所述底电极的侧边。
- 根据权利要求1所述的高频声波谐振器,其特征在于,还包括绝缘件;所述压电薄膜上设有第一通孔;所述第一通孔与所述第一汇流条对应,且所述第一通孔内设有所述绝缘件;所述绝缘件的材料为非压电的绝缘材料。
- 根据权利要求5所述的高频声波谐振器,其特征在于,还包括键合层;所述键合层位于所述支撑衬底与所述底电极之间;所述键合层包括非金属材料和金属材料。
- 根据权利要求1所述的高频声波谐振器,其特征在于,还包括低声速介质层(8);所述低声速介质层(8)位于所述支撑衬底与所述底电极之间;所述低声速介质层(8)包括非金属材料和金属材料。
- 根据权利要求1所述的高频声波谐振器,其特征在于,所述支撑衬底包括层叠的第一衬底和高声速衬底;所述第一衬底的材料为易成型加工的材料;所述高声速衬底的材料为不同晶型及不同切型的碳化硅、金刚石、类金刚石、蓝宝石、氮化铝和氮化硅中的一种。
- 根据权利要求9所述的高频声波谐振器,其特征在于,所述高声速衬底的厚度大于等于0.5倍的所述多个第一电极中相邻的第一电极的中心之间的间隔距离。
- 一种滤波器,其特征在于,包括权利要求1-10任一项所述的高频声波谐振器。
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CN116318017B (zh) * | 2023-02-15 | 2024-04-12 | 锐石创芯(重庆)科技有限公司 | 谐振器、滤波器、电子设备以及谐振器的制备方法 |
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