A high-order acoustic wave filter and communication equipment using the same

Abstract

The present invention relates to the field of microelectronics technology, and in particular to a high-order acoustic wave filter and a communication device using the same. The high-order acoustic wave filter provided by the present invention includes at least one series resonator and at least one parallel resonator; the resonator in the high-order acoustic wave filter includes a supporting substrate, a bottom electrode, a piezoelectric film and a top electrode arranged in sequence from bottom to top; the top electrode is a forked electrode; the target mode of the resonator is a high-order acoustic wave mode generated by excitation of a longitudinal electric field; by making the product of the electrode finger spacing of the top forked electrode of some resonators and the anti-resonance frequency greater than the slow shear wave sound velocity of the supporting substrate, and making all resonators meet the product of the electrode finger spacing of the forked electrode and the upper cutoff frequency of the filter less than the fast shear wave sound velocity of the supporting substrate, it is possible to not only reduce the influence of the parasitic mode of the resonator, but also ensure that the passband of the filter is almost unaffected.

Description

Technical Field

[0001] The present invention relates to the field of microelectronics technology, and in particular to a high-order acoustic wave filter and communication equipment using the same. Background Art

[0002] Modern wireless communication systems are gradually developing towards higher frequencies, which puts higher requirements on some performance of RF filters, such as operating frequency, insertion loss, bandwidth, in-band flatness, out-of-band suppression, power tolerance, temperature stability and other performance.

[0003] However, the operating frequency of the existing bulk acoustic wave (BAW) filter is inversely proportional to the thickness of the piezoelectric film, so in order to increase its operating frequency, the thickness of the piezoelectric film is often reduced. However, a piezoelectric film that is too thin has the problem of mechanical stability. The 0th order surface acoustic wave (SAW) filter is limited by the target mode sound velocity, and its operating frequency is difficult to increase. In addition, although the high-order acoustic wave mode filter based on the longitudinal electric field excitation of the high sound velocity supporting substrate has advantages in frequency, bandwidth, area, and mechanical stability, due to the large bandwidth of this filter, the frequency difference between the series resonator and the parallel resonator that make up the filter is large, and the higher sound velocity mode and its longitudinal mode in the 0th order mode may appear near the passband or even within the passband; this will cause ripples in the passband and transition band of the filter, or a significant decrease in the out-of-band suppression level. Summary of the Invention

[0004] To solve at least one of the above technical problems, the present application discloses, in one aspect, a high-order acoustic wave filter, which includes at least two resonators; the at least two resonators include at least one series resonator and at least one parallel resonator;

[0005] The resonator comprises a supporting substrate, a bottom electrode, a piezoelectric film and a top electrode arranged in sequence from bottom to top; the top electrode is an interdigital electrode;

[0006] The target mode of the resonator is a high-order acoustic wave mode excited by the longitudinal electric field;

[0007] Wherein, all resonators in the high-order acoustic wave filter satisfy the first parameter condition; and at least one resonator in the high-order acoustic wave filter satisfies the second parameter condition;

[0008] The first parameter condition includes: the product of the electrode finger spacing of the resonator and the resonant frequency of the resonator is less than the longitudinal wave sound velocity of the supporting substrate; the electrode finger spacing of the resonator is the distance between the centers of adjacent electrode fingers on the same bus bar of the interdigitated electrode;

[0009] The second parameter condition includes: a product of an electrode finger spacing of the resonator and an antiresonance frequency of the resonator is greater than a slow shear wave speed of the supporting substrate.

[0010] Optionally, the product of the electrode finger spacing of the series resonator and the antiresonance frequency of the series resonator is greater than the slow shear wave speed of the supporting substrate.

[0011] Optionally, a product of an electrode finger spacing of at least one resonator in the high-order acoustic wave filter and an upper cutoff frequency of the high-order acoustic wave filter is smaller than a fast shear wave velocity of the supporting substrate.

[0012] Optionally, the first parameter condition further includes:

[0013] The product of the electrode finger spacing of the resonator and the upper cutoff frequency of the high-order acoustic wave filter is less than the fast shear wave speed of the supporting substrate.

[0014] Optionally, the target mode of the resonator is one or more of a high-order horizontal shear mode, a high-order Lamb wave mode, and a high-order Rayleigh mode.

[0015] Optionally, the material of the piezoelectric film includes at least one of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate, or lead magnesium niobate-lead titanate.

[0016] Optionally, a dielectric layer is further provided between the supporting substrate and the bottom electrode;

[0017] The dielectric layer is a single-layer material or a multi-layer material, including one or more of silicon oxide, silicon nitride, polycrystalline silicon, amorphous silicon, aluminum oxide, and aluminum nitride; or, the dielectric layer is a combination of one or more of a temperature compensation layer, a heat dissipation layer, a trap-rich layer, a bonding layer, and a low acoustic velocity layer.

[0018] Optionally, the support substrate is a high-acoustic-velocity support substrate, and the slow shear wave acoustic velocity of the support substrate exceeds 5000 m / s;

[0019] The material of the support substrate is one or more combinations of silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride in different crystal forms and cut shapes.

[0020] Optionally, the support substrate includes a stacked support layer and a high acoustic velocity layer;

[0021] The thickness of the high acoustic velocity layer is greater than or equal to 0.5 times the electrode finger spacing of the resonator;

[0022] The high acoustic velocity layer is made of a material that is easy to shape and process; the material of the high acoustic velocity layer is any one of silicon carbide, diamond, diamond-like carbon, aluminum oxide, aluminum nitride, boron nitride, boron carbide and silicon nitride of different crystal forms and different cuts;

[0023] The material of the support layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0024] Optionally, the bottom electrode is a suspended bottom electrode;

[0025] The material of the bottom electrode includes one or more combinations of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

[0026] Optionally, the bottom electrode is located between the supporting substrate and the piezoelectric film;

[0027] Alternatively, the bottom electrode is located in the groove of the supporting substrate and contacts the piezoelectric film, and the bottom electrode is a conductive layer formed by a deposition process, or the bottom electrode is a conductive region formed by a doping process;

[0028] The width of the bottom electrode does not exceed the width of the aperture region of the top electrode; the aperture region of the top electrode is the region where multiple electrode fingers in the interdigitated electrode intersect and overlap.

[0029] Optionally, the duty cycle, thickness, and material of the top electrode of each resonator in the high-order acoustic wave filter are the same or different;

[0030] The thickness of the piezoelectric film of each resonator in the high-order acoustic wave filter is the same or different.

[0031] Optionally, the piezoelectric film is located in the aperture area of ​​the top electrode, and the remaining area of ​​the layer where the piezoelectric film is located is filled with dielectric material; the remaining area is the area in the layer where the piezoelectric film is located except the area occupied by the piezoelectric film; the aperture area of ​​the top electrode is the area where multiple electrode fingers in the interdigitated electrode are staggered and overlapped.

[0032] Optionally, a plurality of groove structures are provided on the piezoelectric film;

[0033] The groove structure is located in a region between electrode fingers of the top electrode.

[0034] Optionally, the thickness of the top electrode is 0.01 times the electrode finger spacing to 0.5 times the electrode finger spacing;

[0035] The thickness of the piezoelectric film is 0.05 times the electrode finger spacing to 1 times the electrode finger spacing;

[0036] The thickness of the bottom electrode is 0.01 times to 0.5 times the electrode finger pitch.

[0037] In another aspect, the present application further discloses a communication device, which includes the above-mentioned high-order acoustic wave filter.

[0038] The high-order acoustic wave filter provided by the present application increases λ as much as possible by making the product of the electrode finger spacing λ of the top forked electrode of some resonators and the anti-resonance frequency greater than the slow shear wave sound velocity of the supporting substrate, thereby reducing the frequency of the 0th order mode and its longitudinal mode, making them away from the passband, and reducing the impact of related parasitic responses on the passband and transition band of the filter. And for the parasitic response in the high frequency band, the related parasitic response can be weakened due to the increase in loss in the high frequency band. At the same time, since these resonators meet the requirement that the product of λ and the cut-off frequency on the filter is less than the fast shear wave sound velocity of the supporting substrate, the passband of the filter is almost unaffected. As a result, the main mode of some resonators leaks to the supporting substrate in the non-working frequency band, and the frequency of the parasitic response can be changed or the parasitic response can be weakened without sacrificing the passband of the filter, thereby increasing the electrode finger spacing λ of the top forked electrode required at the same working frequency and reducing the requirements for its lithography accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 A cross-sectional view of an exemplary resonator of the present application;

[0041] Figure 2 A topological diagram of an exemplary high-order acoustic wave filter of the present application;

[0042] Figure 3 A top view of an exemplary top electrode and bottom electrode of the present application;

[0043] Figure 4 A cross-sectional view of another exemplary resonator of the present application;

[0044] Figure 5 Schematic diagram of the admittance curve and conductance curve corresponding to Comparative Example 1;

[0045] Figure 6 Schematic diagram of the admittance curve and conductance curve corresponding to Comparative Example 2;

[0046] Figure 7is the frequency response corresponding to comparative example 3;

[0047] Figure 8 for Figure 7 A local enlarged view of the S21 curve in ;

[0048] Figure 9 An exemplary admittance curve diagram of a set of series resonators of the present application;

[0049] Figure 10 for Figure 9 Corresponding conductance curve;

[0050] Figure 11 for Figure 9 Corresponding Bode-Q curve;

[0051] Figure 12 for Figure 9 The corresponding vibration mode diagrams of each resonator near the anti-resonance frequency;

[0052] Figure 13 for Figure 9 The corresponding vibration mode diagrams of each resonator near the cutoff frequency of the filter;

[0053] Figure 14 The frequency response of the first high-order acoustic wave filter exemplified in this application;

[0054] Figure 15 The frequency response of the second high-order acoustic wave filter exemplified in this application;

[0055] Figure 16 The frequency response of the third high-order acoustic wave filter exemplified in this application;

[0056] Figure 17 The frequency response of the fourth exemplary high-order acoustic wave filter of the present application;

[0057] Figure 18 for Figure 7 and Figure 16 Comparison chart of the S21 curve in;

[0058] Figure 19 for Figure 18 A local enlarged view of the S21 curve;

[0059] Figure 20 for Figure 7 and Figure 17 Comparison chart of the S21 curve in;

[0060] Figure 21 for Figure 20 A local enlarged view of the S21 curve;

[0061] Figure 22An exemplary admittance curve diagram of a set of parallel resonators of the present application;

[0062] Figure 23 for Figure 22 Corresponding conductance curve;

[0063] Figure 24 for Figure 22 Corresponding Bode-Q curve;

[0064] Figure 25 for Figure 22 The corresponding vibration mode diagrams of each resonator near the anti-resonance frequency;

[0065] Figure 26 The frequency response of the fifth high-order acoustic wave filter exemplified in this application;

[0066] Figure 27 The frequency response of the sixth high-order acoustic wave filter of the present application is exemplified;

[0067] Figure 28 The frequency response of the seventh high-order acoustic wave filter of the present application is exemplified;

[0068] Figure 29 for Figure 26 and Figure 16 Comparison chart of the S21 curve in;

[0069] Figure 30 for Figure 29 A local enlarged view of the S21 curve;

[0070] Figure 31 The S21 curve of the eighth high-order acoustic wave filter of this application is shown in FIG. Figure 26 Comparison of the S21 curves.

[0071] The following is a supplementary description of the accompanying drawings:

[0072] 1-series resonator; 2-parallel resonator; 3-support substrate; 4-bottom electrode; 5-piezoelectric film; 6-top electrode; 601-first bus bar; 602-second bus bar; 603-electrode finger; 6031-first electrode finger; 6032-second electrode finger; 604-aperture region; 605-air gap region; 7-dielectric layer. DETAILED DESCRIPTION

[0073] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0074] References to "one embodiment" or "embodiment" herein refer to specific features, structures, or characteristics that may be included in at least one implementation of the present application. Throughout the description of this application, it should be understood that the terms "upper," "lower," "top," and "bottom," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplification. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature designated "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, the terms "first," "second," etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential sequence. It should be understood that such terms are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0075] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein. For example, a specified range from "1 to 10" should be considered to include any and all subranges between a minimum of 1 and a maximum 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.

[0076] Typically, when existing acoustic wave resonators are high-order acoustic wave modes excited by a longitudinal electric field, the phase velocity of the main mode is specified to be less than the slow shear wave velocity of the supporting substrate to prevent leakage of the main mode into the supporting substrate. However, due to the wide bandwidth of filters constructed using these acoustic wave resonators, higher-velocity zero-order modes (such as the longitudinal leakage surface acoustic wave (LL-SAW) SAW mode and the corresponding longitudinal mode of the LL-SAW) will exist as parasitic modes within or near the filter passband.

[0077] To this end, the present application provides a novel filter structure, by making the λ of some resonators constituting the filter and the anti-resonance frequency f pThe product of is greater than the slow shear wave velocity v of the supporting substrate ss , that is, the phase velocity is greater than the slow shear wave speed v of the supporting substrate ss As λ increases, the 0th order mode and its longitudinal mode will move to low frequency, thus away from the passband, achieving the purpose of removing or weakening the parasitic response. The main mode of these resonators will leak a lot to the supporting substrate at the anti-resonance frequency, and the Q value will decrease. But at the same time, these resonators meet the resonator's λ and the filter cutoff frequency f H The product of is less than the fast shear wave speed v of the supporting substrate fs , which ensures that the filter passband is almost unaffected.

[0078] For details, please refer to Figure 1-2 The high-order acoustic wave filter provided in the present application includes at least two resonators; the at least two resonators include at least one series resonator 1 and at least one parallel resonator 2; the resonator includes a supporting substrate 3, a bottom electrode 4, a piezoelectric film 5 and a top electrode 6 arranged in sequence from bottom to top; the top electrode 6 is a forked electrode; the target mode of the resonator is a high-order acoustic wave mode generated by the excitation of the longitudinal electric field; wherein all resonators in the high-order acoustic wave filter meet the first parameter condition; and there is at least one resonator in the high-order acoustic wave filter that meets the second parameter condition; the first parameter condition includes: the product of the electrode finger spacing of the resonator and the resonant frequency of the resonator is less than the longitudinal wave sound velocity v of the supporting substrate 3 L The electrode finger spacing of the resonator is the distance between the centers of adjacent electrode fingers 603 on the same busbar of the interdigitated electrode; the second parameter condition includes: the product of the electrode finger spacing of the resonator and the antiresonance frequency of the resonator is greater than the slow shear wave speed v of the supporting substrate 3 ss In this way, not only the influence of the parasitic mode of the resonator can be reduced, but also the passband of the filter can be almost unaffected. Moreover, since λ can be increased as much as possible, the requirements for the photolithography accuracy of the top electrode 6 are also reduced.

[0079] For example, the lower cutoff frequency of the high-order mode acoustic wave filter is f L , the upper cutoff frequency is f H , f L and f H The frequency range between is the passband of the filter, where the upper cutoff frequency f H Indicates the highest frequency of the filter passband; the lower cutoff frequency is f L Indicates the lowest frequency of the filter passband.

[0080] In an exemplary embodiment, see Figure 3The interdigitated electrodes further include a first bus bar 601 and a second bus bar 602; the electrode fingers 603 include a first electrode finger 6031 and a second electrode finger 6032; the first bus bar 601 is connected to a plurality of the first electrode fingers 6031; the second bus bar is connected to a plurality of the second electrode fingers 6032; the plurality of the first electrode fingers 6031 and the plurality of the second electrode fingers 6032 are staggered along a first direction; the first direction is the width direction of the first electrode finger 6031 or the second electrode finger 6032, which can be specifically Figure 3 . Optionally, the distance between adjacent first electrode fingers 6031 is equal to the distance between adjacent second electrode fingers 6032. Thus, the electrode finger pitch of the acoustic wave resonator can refer to the spacing between adjacent electrode fingers 603 in the same bus bar, which can be denoted as λ. Specifically, the spacing between the centers of adjacent first electrode fingers 6031 and the centers of second electrode fingers 6032 is λ / 2, the spacing between the centers of adjacent first electrode fingers 6031 is λ, and the spacing between the centers of adjacent second electrode fingers 6032 is λ. The aperture region 604 is the area where multiple first electrode fingers 6031 and multiple second electrode fingers 6032 overlap. The interdigitated electrode further includes an air gap region 605, which is the area between the free ends of the second electrode fingers 6032 and the first bus bar 601, and the area between the free ends of the first electrode fingers 6031 and the second bus bar 602. That is, the aperture region 604 is the region where the plurality of electrode fingers 603 overlap and intersect; the air gap region 605 is the region between the free end of the electrode finger 603 and the bus bar on the opposite side of the electrode finger 603 .

[0081] In a feasible embodiment, the target mode of the resonator is one or more of a high-order horizontal shear mode, a high-order Lamb wave mode, and a high-order Rayleigh mode.

[0082] In a feasible embodiment, the material of the piezoelectric film 5 includes at least one of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate, or lead magnesium niobate-lead titanate.

[0083] In one feasible embodiment, the piezoelectric film 5 may be located only within the aperture region 604 of the top electrode 6, with the remaining area of ​​the layer containing the piezoelectric film 5 filled with a dielectric material. The remaining area is the area of ​​the layer containing the piezoelectric film 5 excluding the area occupied by the piezoelectric film 5. The aperture region 604 of the top electrode 6 is the region where the multiple electrode fingers 603 of the interdigitated electrode intersect and overlap. In another feasible embodiment, the piezoelectric film 5 may be spread over the entire top electrode 6 region, which is not a limitation here.

[0084] In one feasible embodiment, the piezoelectric film 5 is provided with a plurality of groove structures; the groove structures are located in the regions between the electrode fingers 603 of the top electrode 6. Alternatively, a groove structure may be provided in the piezoelectric film 5 corresponding to the region between each adjacent electrode finger 603, or a groove structure may be provided in the piezoelectric film 5 only in the regions between adjacent electrode fingers 603 among some of the electrode fingers 603.

[0085] In one feasible embodiment, the bottom electrode 4 may be a suspended bottom electrode 4 ; the material of the bottom electrode 4 includes one or more of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride. Optionally, the bottom electrode 4 may be a surface electrode or an interdigitated electrode, without limitation.

[0086] In one feasible embodiment, the bottom electrode 4 is located between the supporting substrate 3 and the piezoelectric film 5, that is, the upper surface of the bottom electrode 4 contacts the lower surface of the piezoelectric film 5, and the lower surface of the bottom electrode 4 contacts the upper surface of the supporting substrate 3; in another feasible embodiment, the bottom electrode 4 can also be embedded in the supporting substrate 3. Specifically, the supporting substrate 3 includes a groove, so that the supporting substrate 3 has a concave structure, and the bottom electrode 4 is located in the groove. At this time, the upper surface of the bottom electrode 4 contacts the lower surface of the piezoelectric film 5, and the other surfaces of the bottom electrode 4 are in contact with the groove of the supporting substrate 3. Optionally, the bottom electrode 4 located in the groove can be formed by a conventional deposition process to form a conductive layer, or it can be formed by a doping process. The specific doping process can be ion implantation or thermal diffusion to a preset depth of the supporting substrate 3 to form a conductive region.

[0087] In one possible implementation, see Figure 3 The width of the bottom electrode 4 may not exceed the width of the aperture region 604 of the top electrode 6; the aperture region 604 of the top electrode 6 is the region where the multiple electrode fingers 603 in the interdigitated electrode intersect and overlap.

[0088] In a feasible embodiment, the duty cycle of the top electrode 6, the thickness of the top electrode 6, and the material of the top electrode 6 of each resonator in the high-order acoustic wave filter can be the same or different. Optionally, the thickness of the piezoelectric film 5 of each resonator in the high-order acoustic wave filter can be the same or different.

[0089] In a feasible embodiment, the supporting substrate 3 is a high-acoustic-velocity supporting substrate, and the slow shear wave acoustic velocity of the supporting substrate 3 exceeds 5000 m / s; the material of the supporting substrate 3 is a combination of one or more of silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride of different crystal forms and different cuts.

[0090] In a feasible embodiment, the supporting substrate 3 includes a stacked supporting layer and a high acoustic velocity layer; the thickness of the high acoustic velocity layer is greater than or equal to 0.5 times the electrode finger spacing of the resonator; the high acoustic velocity layer is a material that is easy to form and process; the material of the high acoustic velocity layer is any one of silicon carbide, diamond, diamond-like carbon, aluminum oxide, aluminum nitride, boron nitride, boron carbide and silicon nitride of different crystal forms and different cuts; the material of the supporting layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0091] In one possible implementation, see Figure 4 A dielectric layer 7 is further provided between the supporting substrate 3 and the bottom electrode 4; the dielectric layer 7 is a single-layer material or a multi-layer material, including one or more of silicon oxide, silicon nitride, polycrystalline silicon, amorphous silicon, aluminum oxide, and aluminum nitride. In another feasible embodiment, the dielectric layer 7 is a combination of one or more of a temperature compensation layer, a heat dissipation layer, a trap-rich layer, a bonding layer, and a low acoustic velocity layer.

[0092] In a feasible embodiment, the thickness of the top electrode 6 is 0.01 times the electrode finger pitch to 0.5 times the electrode finger pitch; that is, the thickness of the top electrode 6 can be 0.01λ to 0.5λ, specifically, the thickness of the top electrode 6 can be 0.01λ, 0.05λ, 0.1λ, 0.2λ, 0.3λ, 0.4λ or 0.5λ. The thickness of the piezoelectric film 5 is 0.05 times the electrode finger pitch to 1 times the electrode finger pitch; that is, the thickness of the top electrode 6 can be 0.05λ to λ, specifically, the thickness of the piezoelectric film 5 can be 0.05λ, 0.1λ, 0.2λ, 0.3λ, 0.4λ, 0.5λ, 0.6λ, 0.7λ, 0.8λ, 0.9λ or λ. The thickness of the bottom electrode 4 is 0.01 times the electrode finger pitch to 0.5 times the electrode finger pitch; that is, the thickness of the bottom electrode 4 can be 0.01λ to 0.5λ. Specifically, the thickness of the bottom electrode 4 can be 0.01λ, 0.05λ, 0.1λ, 0.2λ, 0.3λ, 0.4λ or 0.5λ.

[0093] In a feasible embodiment, the electrode finger spacing λ of the series resonator 1 is equal to the anti-resonance frequency f of the series resonator 1. p The product of is greater than the slow shear wave speed v of the supporting substrate 3 ss That is, λf p>v ss Thus, although the admittance response of the series resonator 1 exceeds f H The loss in some frequency bands is extremely large, but the filter's passband still maintains low insertion loss.

[0094] In a feasible embodiment, there is at least one resonator in the high-order acoustic wave filter with an electrode finger spacing λ that is equal to the upper cutoff frequency f of the high-order acoustic wave filter. H The product of is less than the fast shear wave speed v of the supporting substrate 3 fS , that is, λf H <v fS In this way, when increasing λ, the filter passband can still maintain a lower insertion loss. In order to further reduce the insertion loss of the filter passband, in a feasible embodiment, the first parameter condition also includes: the electrode finger spacing λ of the resonator and the upper cutoff frequency f of the high-order acoustic wave filter H The product of is less than the fast shear wave speed v of the supporting substrate 3 fS , that is, λf H <v fS .

[0095] The principles and technical effects of the above-mentioned filter provided by this application will be described in detail below with specific comparative examples and embodiments.

[0096] Provide a pair of ratios 1, corresponding to Figure 4 The structure shown in FIG. 1 includes a supporting substrate 3, a dielectric layer 7, a bottom electrode 4, a piezoelectric film 5, and a top electrode 6 arranged in sequence from bottom to top; the top electrode 6 is an interdigitated electrode; the target mode of the resonator is a high-order acoustic wave mode excited by a longitudinal electric field; specifically, comparative example 1 is a parallel resonator 2, and the electrode finger spacing of the top electrode 6 can be recorded as λ p The material of the supporting substrate 3 is 4H-SiC, and the slow shear wave velocity v of the supporting substrate 3 is ss =7119m / s, fast shear wave speed v fs =7787m / s; the material of the dielectric layer 7 is silicon oxide, with a thickness of 100nm; the material of the bottom electrode 4 is tungsten, with a thickness of 35nm; the material of the piezoelectric film 5 is X-cut lithium niobate, with a thickness of 223nm; the top electrode 6 is 50nm of chromium, λ p =1μm, the main mode is SH1 mode, due to the anti-resonance frequency f of comparative example 1 p Lower than v ss / λ p , ensuring that the main mold will not leak to the supporting substrate 3, and subsequent relevant calculations can be performed to obtain the following Figure 5The admittance and conductance curves shown in the figure show that the longitudinal mode of the LL-SAW mode appears around 6 GHz, which will cause fluctuations in the filter passband. There is also a strong S1 mode around 8.7 GHz, which will lead to a decrease in the out-of-band suppression level.

[0097] Provide another comparative example 2, which corresponds to Figure 4 The structure shown is a series resonator 1, and the electrode finger spacing of the top electrode 6 can be recorded as λ s The material of the supporting substrate 3 is 4H-SiC, and the slow shear wave velocity v of the supporting substrate 3 is ss =7119m / s, fast shear wave speed v fs =7787m / s; the material of the dielectric layer 7 is silicon oxide, with a thickness of 100nm; the material of the bottom electrode 4 is tungsten, with a thickness of 35nm; the material of the piezoelectric film 5 is X-cut lithium niobate, with a thickness of 150nm; the top electrode 6 is 50nm of chromium, λ p =0.9μm, the main mode is SH1 mode, due to the anti-resonance frequency f of comparative example 2 p Close to v ss / λ s If we want to ensure that the main mold does not leak to the supporting substrate 3, it is difficult to further increase λ s . Subsequent relevant calculations can be performed to obtain the following Figure 6 From the admittance curve and conductance curve shown, it can be seen that the LL-SAW mode appears around 5.8 GHz, which will cause severe fluctuations in the left transition band.

[0098] Another comparative example 3 is provided, which is a high-order acoustic wave filter, specifically corresponding to Figure 2 The topological structure shown in FIG. 1 includes three series resonators 1 and two parallel resonators 2, and the series resonator 1 included in Comparative Example 3 is the above-mentioned Comparative Example 2, and the parallel resonator 2 is the above-mentioned Comparative Example 1. Further, by Figure 7 The transmission coefficient (S21) curve of the high-order acoustic wave filter shown in FIG shows that, near 5.8 GHz, the LL-SAW mode of the series resonator 1 causes severe fluctuations in the transition band on the left side of the filter passband. Near 8.7 GHz, the S1 mode of the parallel resonator 2 causes a decrease in the out-of-band suppression level of the corresponding frequency. Figure 7 By zooming in on the local part of the S21 curve, we can get the following Figure 8 As shown in the S21 graph, the longitudinal mode of the LL-SAW mode of the parallel resonator 2 causes fluctuations in the filter passband.

[0099] A set of series resonators 1 is also provided, which corresponds to Figure 4 The structure shown in the figure, the difference between the resonators in this group is only the electrode finger spacing λ sThe specific structural parameters of each resonator in the series resonator group are as follows: the material of the supporting substrate 3 is 4H-SiC; the material of the dielectric layer 7 is silicon oxide with a thickness of 100nm; the material of the bottom electrode 4 is tungsten with a thickness of 35nm; the material of the piezoelectric film 5 is X-cut lithium niobate; the top electrode 6 is 50nm of chromium, and the main mode is SH1 mode. Specifically, the series resonator group 1 includes 5 resonators, and the λ of these 5 resonators is 1. s In order to ensure the same resonant frequency, the thickness of the corresponding piezoelectric film 5 is 150nm, 145nm, 140nm, 135nm, and 131nm respectively. s The smaller the thickness of the corresponding piezoelectric film 5, the thicker it is. Figure 9 The admittance curve of this set of series resonators is shown in Figure 1. It can be seen that the frequency of the SH1 mode remains unchanged, while the frequency of the LL-SAW mode increases with λ. s increases and decreases. s When >0.919μm, the anti-resonance frequency f of the main mode p and λ s The product of is greater than the slow shear wave speed v of the supporting substrate 3 ss , the SH1 mode near the antiresonance frequency leaks to the substrate, so as λ s increases, and the admittance ratio of the main mode decreases significantly.

[0100] Figure 9 The gray shaded area represents the passband of the filter. s When <1.09μm, the upper cutoff frequency f H and λ s The product of is less than the fast shear wave speed v of the supporting substrate 3 fs Therefore, although the leakage degree of the main mode near the antiresonance frequency is different, λ s The admittance curves corresponding to 0.90 to 1.05 μm almost coincide within the filter passband frequency range.

[0101] See also Figure 10 , which is shown as Figure 9 The corresponding conductance curve shows that as λ s As λ increases, the conductance near the antiresonance frequency increases, which indicates an increase in the corresponding frequency loss. s The conductivity curves corresponding to 0.90 to 1.05 μm almost overlap within the filter passband frequency range.

[0102] See also Figure 11 , which is shown as Figure 9The corresponding Bode-Q curve shows that as λ s increases, the Q value near the anti-resonance frequency decreases, but λ s The Bode-Q curves corresponding to 0.90 to 1.05 μm almost overlap within the filter passband frequency range.

[0103] See also Figure 12 , which is shown as Figure 9 The corresponding vibration mode diagrams of each resonator near the anti-resonance frequency are taken at a frequency of 7750MHz. It can be seen that for λ s =0.90μm, due to the anti-resonance frequency f p and λ s The product of is less than v ss , the main mode hardly leaks to the supporting substrate 3, and the loss near the antiresonance frequency is low. s =0.95μm, f p and λ s The product is greater than ν ss , but f p and λ s The product is still less than the fast shear wave speed ν fs， The leakage of the main mode to the supporting substrate 3 increases. s For ≥1.00μm, f p and λ s The product of is not only greater than v ss , is greater than v fs At this time, the main mold has completely leaked into the supporting substrate 3. Figure 11 It can be seen that the Q value of the corresponding frequency is almost 0.

[0104] See also Figure 13 , which is shown as Figure 9 The vibration mode diagram of each resonator near the cutoff frequency of the filter is taken at a frequency of 7125MHz. It can be seen that for λ s is 0.90μm and 0.95μm, due to the upper cutoff frequency f H and λ s The product of is less than v ss , the main mode hardly leaks to the supporting substrate 3. s 1.00μm and 1.05μm, f H and λ s The product is greater than v ss , but f p and λ s The product is still less than the fast shear wave speed v fs， The leakage of the main mode to the supporting substrate 3 increases, but the loss remains at a low level. s When f is 1.10μm,p and λ s The product of is not only greater than v ss , is greater than v fs At this time, the main mold has completely leaked into the supporting substrate 3. Figure 11 It can be seen that the corresponding Bode-Q curve has dropped to almost 0 at the edge of the filter passband.

[0105] See also Figure 14 , which shows the frequency response of the first exemplary high-order acoustic wave filter of the present application, which is Figure 7 The difference is that Figure 14 The λ of the series resonator of the high-order acoustic wave filter s As can be seen from the S21 curve, since the frequency of the LL-SAW mode of the series resonator 1 drops to near the zero point of the filter, its response in the filter is greatly weakened. H The frequency band has not yet leaked, and the passband performance of the filter is Figure 7 There is almost no difference.

[0106] See also Figure 15 , which shows the frequency response of the second exemplary high-order acoustic wave filter of the present application, which is Figure 7 The difference is that Figure 15 The top electrode spacing of the series resonator of the high-order acoustic wave filter is 6 λ s From the S21 curve, it can be seen that the LL-SAW mode of the series resonator 1 is relatively Figure 14 It further decreases, but is still near zero, and its response in the filter is still greatly weakened. H The frequency band has not yet leaked, and the passband performance of the filter is Figure 7 There is almost no difference.

[0107] See also Figure 16 , which shows the frequency response of the third exemplary high-order acoustic wave filter of the present application, which is Figure 7 The difference is that Figure 16 The top electrode 6 spacing of the series resonator of the high-order acoustic wave filter is λ s It can be seen from the S21 curve that the LL-SAW mode of series resonator 1 is relatively Figure 15 It further decreases, but is still near zero, and its response in the filter is still greatly weakened. ss / λ s <f H <v fs / λ s There is a small amount of leakage on the high-frequency side of the filter passband, but the increase in loss is very small. The passband performance of the filter is similar to Figure 7 Still almost no difference.

[0108] See also Figure 17 , which shows the frequency response of the fourth exemplary high-order acoustic wave filter of the present application, which is Figure 7 The difference is that Figure 17 The top electrode 6 spacing of the series resonator of the high-order acoustic wave filter is λ s From the S21 curve, it can be seen that the LL-SAW mode of series resonator 1 is relatively Figure 16 It has further declined and has begun to move away from zero. Figure 14 This has caused the out-of-band suppression level of this frequency to decrease. H >v fs / λ s , there is a lot of leakage on the high-frequency side of the filter passband, and the loss on the high-frequency side of the filter passband is relatively low compared to Figure 7 A substantial increase.

[0109] See also Figure 18 , which is shown as Figure 7 and Figure 16 From the comparison of the S21 curve in the figure, it can be seen that when λ s When the frequency is 1.05μm, the flatness of the transition band and the out-of-band suppression are improved, and not only the parasitic response corresponding to the LL-SAW moves to a lower frequency band. H The loss in the frequency band increases, and the parasitic response caused by the S1 mode of the parallel resonator 2 is also greatly reduced. For further information, please refer to Figure 19 , which is shown as Figure 18 From the local enlarged view of the S21 curve, it can be seen that within the passband of the filter, only the loss on the high-frequency side increases slightly.

[0110] See also Figure 20 , which is shown as Figure 7 and Figure 17 From the comparison of the S21 curve in the figure, it can be seen that when λ s When the wavelength is 1.10μm, the flatness of the transition band and the out-of-band suppression are improved. Figure 21 , which is shown as Figure 20 A local enlarged view of the S21 curve shows that within the passband of the filter, the loss on the high-frequency side increases significantly, which directly leads to a significant reduction in the effective bandwidth of the filter.

[0111] Through the performance analysis of the above-mentioned set of series resonators 1 and the corresponding high-order filters, it can be seen that the series resonator 1 can meet the requirements of f H <v fs / λ s Under the premise of flexible selection of top electrode 6 spacing λs In order to reduce the requirements of lithography accuracy and improve power tolerance, it is usually possible to increase λ as much as possible. s In order to make the LL-SAW parasitic mode appear near the zero point of the filter to weaken the related parasitic response, the λ of the series resonator 1 can be selected s More than v fs / f P . In addition, the series resonator 1 is larger than f H The loss in the frequency band increases, and the spurious response caused by the S1 mode of parallel resonator 2 is also greatly reduced.

[0112] A set of parallel resonators 2 is also provided, which corresponds to Figure 4 The structure shown in the figure, the difference between the resonators in this group is only the electrode finger spacing λ p and the thickness of the piezoelectric film 5. The specific structural parameters of each resonator in the group of parallel resonators 2 are as follows: the material of the supporting substrate 3 is 4H-SiC, the longitudinal wave sound velocity v L The speed is 12484 m / s; the dielectric layer 7 is made of silicon oxide with a thickness of 100 nm; the bottom electrode 4 is made of tungsten with a thickness of 35 nm; the piezoelectric film 5 is made of X-cut lithium niobate; the top electrode 6 is made of 50 nm chromium, and the main mode is the SH1 mode. Specifically, the parallel resonator group 2 includes 5 resonators, and the λ of these 5 resonators is p In order to ensure the same resonant frequency, the thickness of the corresponding piezoelectric film 5 is 223nm, 216nm, 210nm, and 204nm respectively. p The smaller the thickness of the corresponding piezoelectric film 5, the thicker it is. Figure 22 The admittance curve of this set of parallel resonators is shown. It can be seen that the frequency of LL-SAW increases with λ p The sound velocity of the S1 mode is lower than the longitudinal wave sound velocity v of the supporting substrate 3. L , so it will not leak completely to the supporting substrate 3, but will p For example, λ p When the value is 1.00μm and 1.05μm, f H and λ p The product is greater than v ss , but f H and λ p The product is still less than the fast shear wave speed v of the supporting substrate 3 fs , the loss is small, and the two admittance curves basically coincide within the filter passband frequency range. p When the filter is 1.10μm and 1.15μm, the upper cutoff frequency f H and λp The product of is greater than the fast shear wave speed ν of the supporting substrate 3 fs , so the admittance curve is consistent with λ in the passband frequency range p =1.00μm, there is no overlap.

[0113] See also Figure 23 , which is shown as Figure 22 The corresponding conductance curve shows that λ p The conductivity curves corresponding to 1.00 to 1.05 μm almost overlap within the filter passband frequency range. p When f H The conductance values ​​near the φ 0.05V increase, which indicates an increase in loss at the corresponding frequency.

[0114] See also Figure 24 , which is shown as Figure 22 The corresponding Bode-Q curve shows that as λ p Increase, f H The Q value decreases near λ p It drops to almost 0 when it reaches 1.1μm.

[0115] See also Figure 25 , which is shown as Figure 22 The vibration mode diagram of each resonator near the cutoff frequency of the filter is taken at a frequency of 7125MHz. p 1.00μm and 1.05μm, f H and λ p The product is greater than v ss , but f p and λ p The product is still less than the fast shear wave speed v fs， The leakage of the main mode to the supporting substrate 3 increases, but the loss remains at a low level. p When the f p and λ p The product of is not only greater than v ss , is greater than v fs At this time, the main mold has completely leaked into the supporting substrate 3. Figure 24 It can be seen that the corresponding Bode-Q curve has dropped to almost 0 at the edge of the filter passband.

[0116] See also Figure 26 , which shows the frequency response of the fifth exemplary high-order acoustic wave filter of the present application, and Figure 16 The difference is that Figure 26 The electrode finger spacing λ of the parallel resonator of the high-order acoustic wave filter pIt is 1.05μm. From the S21 curve, it can be seen that the S1 mode of the parallel resonator 2 is larger than λ p When it is 1.00μm, the out-of-band fluctuation in the filter caused by it is also significantly weakened. ss / λ p <f H <v fs / λ p There is a small amount of leakage on the high-frequency side of the filter passband, but the increase in loss is very small. The passband performance of the filter is similar to Figure 7 There is almost no deterioration compared to the previous one.

[0117] See also Figure 27 , which shows the frequency response of the sixth exemplary high-order acoustic wave filter of the present application, and Figure 16 The difference is that Figure 27 The λ of the parallel resonator of the high-order acoustic wave filter p From the S21 curve, it can be seen that the LL-SAW mode of series resonator 1 is relatively Figure 26 It has further declined and has begun to move away from zero. Figure 26 This has caused the out-of-band suppression level of this frequency to decrease. H >v fs / λ p , there is a lot of leakage on the high-frequency side of the filter passband, and the loss on the high-frequency side of the filter passband is relatively low compared to Figure 26 A substantial increase.

[0118] See also Figure 28 , which shows the frequency response of the seventh exemplary high-order acoustic wave filter of the present application, the frequency response of a high-order mode acoustic wave filter, and Figure 16 The difference is that Figure 28 The parallel resonator λ of the high-order acoustic wave filter 2 p As can be seen from the S21 curve, due to the increase in the frequency range of leakage, the loss of the filter's passband high frequency side is smaller than that of Figure 27 Further increase.

[0119] See also Figure 29 , which is shown as an example of this application Figure 26 and Figure 16 The comparison of the S21 curve shows that when λ p When the frequency is 1.05μm, the out-of-band suppression level of the corresponding frequency is further improved due to the weakening of the S1 mode of the parallel resonator 2. For further information, please refer to Figure 30 , which is shown as Figure 29 The corresponding local enlarged view of the S21 curve, when λ pWhen the wavelength is 1.05 μm, the in-band loss hardly changes, and the in-band flatness of the filter is significantly improved because the longitudinal mode frequency of the LL-SAW of the parallel resonator 2 is reduced to outside the passband.

[0120] See also Figure 31 , which shows the S21 curve of the eighth high-order acoustic wave filter of the present application and Figure 26 The comparison of the S21 curve of Figure 26 The corresponding high-order acoustic wave filter has a parallel resonator 2 by λ p =1.10μm resonator, the eighth high-order acoustic wave filter can be obtained. It can be seen that the out-of-band suppression level is further improved.

[0121] Through the performance analysis of the above-mentioned set of parallel resonators 2 and the corresponding high-order filters, it can be seen that for the parallel resonator 2, when f H >v fs / λ p It will also lead to an increase in the loss on the high-frequency side of the filter passband, but the effect is weaker than that of the series resonator 1. p >v fs / f H Replacing the original resonator with a new resonator will not significantly deteriorate the passband performance and will help further improve the out-of-band suppression level.

[0122] In another aspect, the present application also discloses a communication device comprising the aforementioned high-order acoustic wave filter. Communication devices are typically used to transmit information, either wired or wirelessly. Therefore, communication devices can be categorized as wired communication devices and wireless communication devices based on the information transmission method. Wired communication devices include computers, televisions, telephones, PCMs, optical transceivers, and servers. Wireless communication devices include satellites, radio stations, wireless television (on buses or subways), wireless local area networks, and mobile phones.

[0123] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A high-order acoustic wave filter, characterized in that comprising at least two resonators; the at least two resonators comprising at least one series resonator and at least one parallel resonator; The resonator comprises a supporting substrate, a bottom electrode, a piezoelectric film and a top electrode arranged in sequence from bottom to top; the top electrode is an interdigital electrode; The target mode of the resonator is a high-order acoustic wave mode excited by the longitudinal electric field; Wherein, all resonators in the high-order acoustic wave filter satisfy a first parameter condition, and at least one resonator in the high-order acoustic wave filter satisfies a second parameter condition; The first parameter condition includes: the product of the electrode finger spacing of the resonator and the resonant frequency of the resonator is less than the longitudinal wave sound velocity of the supporting substrate; the electrode finger spacing of the resonator is the distance between the centers of adjacent electrode fingers on the same bus bar of the interdigitated electrode; The second parameter condition includes: the product of the electrode finger spacing of the resonator and the antiresonance frequency of the resonator is greater than the slow shear wave speed of the supporting substrate; The product of the electrode finger spacing of the series resonator and the antiresonance frequency of the series resonator is greater than the slow shear wave speed of the supporting substrate; The product of the electrode finger spacing of at least one resonator in the high-order acoustic wave filter and the upper cutoff frequency of the high-order acoustic wave filter is smaller than the fast shear wave speed of the supporting substrate.

2. The high-order acoustic wave filter according to claim 1, wherein The first parameter condition further includes: a product of an electrode finger spacing of the resonator and an upper cutoff frequency of the high-order acoustic wave filter is less than a fast shear wave speed of the supporting substrate.

3. The high-order acoustic wave filter according to claim 1, wherein The target mode of the resonator is one or more of a high-order horizontal shear mode, a high-order Lamb wave mode, and a high-order Rayleigh mode.

4. The high-order acoustic wave filter according to claim 1, wherein The material of the piezoelectric film includes at least one of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate or lead magnesium niobate-lead titanate.

5. The high-order acoustic wave filter according to any one of claims 1 to 4, characterized in that: A dielectric layer is further provided between the supporting substrate and the bottom electrode; The dielectric layer is a single-layer material or a multi-layer material, including one or more of silicon oxide, silicon nitride, polycrystalline silicon, amorphous silicon, aluminum oxide, and aluminum nitride; or, the dielectric layer is a combination of one or more of a temperature compensation layer, a heat dissipation layer, a trap-rich layer, a bonding layer, and a low acoustic velocity layer.

6. The high-order acoustic wave filter according to claim 1, wherein The support substrate is a high-acoustic-velocity support substrate, and the slow shear wave acoustic velocity of the support substrate exceeds 5000 m / s; The material of the support substrate is one or more combinations of silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride in different crystal forms and cut shapes.

7. The high-order acoustic wave filter according to claim 1, wherein The support substrate includes a stacked support layer and a high acoustic velocity layer; The thickness of the high acoustic velocity layer is greater than or equal to 0.5 times the electrode finger spacing of the resonator; The high acoustic velocity layer is made of a material that is easy to shape and process; the material of the high acoustic velocity layer is any one of silicon carbide, diamond, diamond-like carbon, aluminum oxide, aluminum nitride, boron nitride, boron carbide and silicon nitride of different crystal forms and different cuts; The material of the support layer includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

8. The high-order acoustic wave filter according to claim 1, wherein The bottom electrode is a suspended bottom electrode; The material of the bottom electrode includes one or more combinations of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

9. The high-order acoustic wave filter according to claim 8, wherein The bottom electrode is located between the supporting substrate and the piezoelectric film; Alternatively, the bottom electrode is located in the groove of the supporting substrate and contacts the piezoelectric film; the bottom electrode is a conductive layer formed by a deposition process, or the bottom electrode is a conductive region formed by a doping process; The width of the bottom electrode does not exceed the width of the aperture region of the top electrode; the aperture region of the top electrode is the region where multiple electrode fingers in the interdigitated electrode intersect and overlap.

10. The high-order acoustic wave filter according to claim 1, wherein The duty cycle, thickness and material of the top electrode of each resonator in the high-order acoustic wave filter are the same or different; The thickness of the piezoelectric film of each resonator in the high-order acoustic wave filter is the same or different.

11. The high-order acoustic wave filter according to claim 1, wherein The piezoelectric film is located in the aperture area of ​​the top electrode, and the remaining area of ​​the layer where the piezoelectric film is located is filled with dielectric material; the remaining area is the area in the layer where the piezoelectric film is located except the area occupied by the piezoelectric film; the aperture area of ​​the top electrode is the area where multiple electrode fingers in the interdigitated electrode are staggered and overlapped.

12. The high-order acoustic wave filter according to claim 1, wherein The piezoelectric film is provided with a plurality of groove structures; The groove structure is located in a region between electrode fingers of the top electrode.

13. The high-order acoustic wave filter according to claim 1, wherein The thickness of the top electrode is 0.01 times the electrode finger spacing to 0.5 times the electrode finger spacing; The thickness of the piezoelectric film is 0.05 times the electrode finger spacing to 1 times the electrode finger spacing; The thickness of the bottom electrode is 0.01 times to 0.5 times the electrode finger pitch.

14. A communication device, characterized in that: The method comprises the high-order acoustic wave filter according to any one of claims 1 to 13.

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