High-order acoustic wave filter and communication equipment applying same

Abstract

The invention relates to the technical field of microelectronics, in particular to a high-order acoustic wave filter and communication equipment applying the same. The high-order acoustic wave filter provided by the invention comprises at least one series resonator and at least one parallel resonator, a resonator in the high-order acoustic wave filter comprises a supporting substrate, a bottom electrode, a piezoelectric film and a top electrode which are sequentially arranged from bottom to top. The top electrode is an interdigital electrode; the target mode of the resonator is a high-order sound wave mode generated by excitation of a longitudinal electric field; the product of the electrode finger spacing of the top interdigital electrodes of part of the resonators and the anti-resonant frequency is larger than the slow shear wave sound velocity of the supporting substrate, and the product of the electrode finger spacing of the interdigital electrodes of all the resonators and the upper cut-off frequency of the filter is smaller than the fast shear wave sound velocity of the supporting substrate. Therefore, the influence caused by the parasitic mode of the resonator can be reduced, and the passband of the filter can be ensured to be hardly influenced.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic technology, and in particular to a high-order acoustic wave filter and a communication device 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, it is often achieved by reducing the thickness of the piezoelectric film. However, too thin piezoelectric films have problems with 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 support 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 constitute 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 in 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, on one hand, 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: the product of the electrode finger spacing of the resonator and the antiresonance frequency of the resonator is greater than the slow shear wave sound velocity of the supporting substrate.

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

[0011] Optionally, 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.

[0012] Optionally, the first parameter condition also 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 smaller than the fast shear wave sound velocity 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 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 cut shapes.

[0020] Optionally, the support substrate comprises a stacked support layer and a high sound 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 a plurality of electrode fingers in the interdigitated electrode overlap in an interlaced manner.

[0029] Optionally, the duty cycle of the top electrode, the thickness of the top electrode, and the 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 of the electrode finger spacing.

[0037] The present application further discloses a communication device in another aspect, 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 influence 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, these resonators satisfy that the product of λ and the upper cutoff frequency of the filter is less than the fast shear wave sound velocity of the supporting substrate, so 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 photolithography accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 creative work.

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

[0041] Figure 2 A topological diagram of a high-order acoustic wave filter exemplified in 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 partial enlarged view of the S21 curve in ;

[0048] Fig. 9 An exemplary admittance curve diagram of a group of series resonators of the present application;

[0049] Fig.10 for Fig. 9 The corresponding conductivity curve;

[0050] Fig.11 for Fig. 9 Corresponding Bode-Q curve graph;

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

[0052] Fig.13 for Fig. 9 The corresponding vibration mode diagram of each resonator near the cutoff frequency of the filter;

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

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

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

[0056] Fig.17 The frequency response of the fourth high-order acoustic wave filter exemplified in the present application;

[0057] Fig.18 for Figure 7 and Fig.16 Comparison chart of S21 curves in ;

[0058] Fig.19 for Fig.18 A partial enlarged view of the S21 curve;

[0059] Fig. 20 for Figure 7 and Fig.17 Comparison chart of S21 curves in ;

[0060] Fig.21 for Fig. 20 A partial enlarged view of the S21 curve;

[0061] Fig. 22An exemplary admittance curve diagram of a group of parallel resonators of the present application;

[0062] Fig.23 for Fig. 22 The corresponding conductivity curve;

[0063] Fig.24 for Fig. 22 Corresponding Bode-Q curve graph;

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

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

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

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

[0068] Fig.29 for Fig.26 and Fig.16 Comparison chart of S21 curves in ;

[0069] Fig.30 for Fig.29 A partial enlarged view of the S21 curve;

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

[0071] The following is a supplementary description of the attached 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 technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0074] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may include one or more of the features explicitly or implicitly. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here.

[0075] When a numerical range is disclosed herein, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges included therein. For example, a specified range from "1 to 10" should be deemed to include any and all sub-ranges between a minimum of 1 and a maximum of 10. Exemplary sub-ranges of ranges 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0076] Generally, when the existing acoustic wave resonator is a high-order acoustic wave mode excited by a longitudinal electric field, in order to ensure that the main mode does not leak to the supporting substrate, the phase velocity of the main mode is specified to be less than the slow shear wave sound velocity of the supporting substrate. However, due to the large bandwidth of the filter composed of the above-mentioned acoustic wave resonator, the 0th order mode with a higher sound velocity (such as the SAW longitudinal leakage surface acoustic wave (LL-SAW) mode and the longitudinal mode corresponding to the LL-SAW) will exist as a parasitic mode in 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 velocity v of the supporting substrate ss As λ increases, the 0th order mode and its longitudinal mode will move to low frequency, thus moving away from the passband, achieving the purpose of removing or weakening parasitic responses. 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 upper 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 barely affected.

[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 a longitudinal electric field; wherein all resonators in the high-order acoustic wave filter satisfy a first parameter condition; and there is at least one resonator in the high-order acoustic wave filter that 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 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 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 sound velocity 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 ensured to be almost unaffected. Moreover, since λ can be increased as much as possible, the requirement of the photolithography precision of the top electrode 6 is also reduced.

[0079] Exemplarily, 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 Represents the lowest frequency of the filter passband.

[0080] In an exemplary embodiment, see Figure 3The interdigitated electrode further includes a first bus bar 601 and a second bus bar 602; the electrode finger 603 includes 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 may be Figure 3 . Optionally, the distance between adjacent first electrode fingers 6031 is equal to the distance between adjacent second electrode fingers 6032. Therefore, the electrode finger spacing of the acoustic wave resonator may refer to the spacing between adjacent electrode fingers 603 in the same bus bar, which may 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 region where a plurality of the first electrode fingers 6031 and a plurality of the second electrode fingers 6032 overlap; the interdigitated electrode further includes an air gap region 605, which is the region between the free end of the second electrode finger 6032 and the first bus bar 601, and the region between the free end of the first electrode finger 6031 and the second bus bar 602. That is to say, the aperture region 604 is a region where a plurality of the electrode fingers 603 are staggered and overlapped; the air gap region 605 is a 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 implementation, 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 implementation, 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 a feasible implementation, the piezoelectric film 5 may be located only in the aperture area 604 of the top electrode 6, and the remaining area of ​​the layer where the piezoelectric film 5 is located is filled with dielectric material; the remaining area is the area of ​​the layer where the piezoelectric film 5 is located except the area occupied by the piezoelectric film 5; the aperture area 604 of the top electrode 6 is the area where multiple electrode fingers 603 in the interdigitated electrode overlap. In another feasible implementation, the piezoelectric film 5 can also be spread over the entire top electrode 6 area, which is not limited here.

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

[0085] In a feasible implementation, the bottom electrode 4 may be a suspended bottom electrode 4; the material of the bottom electrode 4 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. Optionally, the bottom electrode 4 may be a surface electrode or a forked finger electrode, which is not limited here.

[0086] In a feasible embodiment, the bottom electrode 4 is located between the support 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 support substrate 3; in another feasible embodiment, the bottom electrode 4 can also be embedded in the support substrate 3. Specifically, the support substrate 3 includes a groove, so that the support 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 support substrate 3. Optionally, the molding process of the bottom electrode 4 located in the groove can be a conductive layer formed by a conventional deposition process, or it can be formed by a doping process. The specific doping process can be a conductive region formed by ion implantation or thermal diffusion to a preset depth of the support substrate 3.

[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 plurality of electrode fingers 603 in the interdigitated electrode are staggered and overlapped.

[0088] In a feasible implementation, 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 5000m / 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 cutting shapes.

[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 implementation manner, the thickness of the top electrode 6 is 0.01 times the electrode finger spacing to 0.5 times the electrode finger spacing; that is, the thickness of the top electrode 6 can be 0.01λ to 0.5λ, and 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 spacing to 1 times the electrode finger spacing; that is, the thickness of the top electrode 6 can be 0.05λ to λ, and 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 implementation manner, the electrode finger spacing λ of the series resonator 1 is related to the anti-resonance frequency f of the series resonator 1. p The product of is greater than the slow shear wave velocity 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 passband still maintains a low insertion loss.

[0094] In a feasible implementation manner, 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 λ is increased, 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 implementation, 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 principle and technical effects of the above-mentioned filter provided by the present 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 a forked 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 Below 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 5From the admittance curve and conductance curve shown, it can be seen that the longitudinal mode of the LL-SAW mode appears near 6GHz, which will cause fluctuations in the filter passband. There is also a strong S1 mode near 8.7GHz, which will lead to a decrease in the out-of-band suppression level.

[0097] Another comparative example 2 is provided, which corresponds to Figure 4 The structure shown in FIG. 1 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 . The following relevant calculations can be performed to obtain Figure 6 From the admittance curve and conductance curve shown, it can be seen that the LL-SAW mode appears near 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 the figure 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 the out-of-band suppression level of the corresponding frequency to decrease. Furthermore, by Figure 7 By zooming in on the local part of the S21 curve in 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 FIG. 1 is a structure in which the difference between the resonators in the group of resonators 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 support 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 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 s They are 0.90 μm, 0.95 μm, 1.00 μm, 1.05 μm, and 1.10 μm, respectively. In order to ensure the same resonant frequency, the corresponding thicknesses of the piezoelectric film 5 are 150 nm, 145 nm, 140 nm, 135 nm, and 131 nm, respectively. That is, λ s The smaller the thickness of the corresponding piezoelectric film 5 is, the thicker it is. Fig. 9 The admittance curve of this set of series resonators is shown in Figure 2. 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 of the main mode is f p With λ s The product of is greater than the slow shear wave velocity 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] Fig. 9 The medium gray shaded area represents the passband of the filter. s When <1.09μm, the upper cutoff frequency f of the filter H With 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 0.90-1.05 μm almost overlap within the filter passband frequency range.

[0101] See also Fig.10 , which is shown as Fig. 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 0.90-1.05 μm almost overlap within the filter passband frequency range.

[0102] See also Fig.11 , which is shown as Fig. 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 Fig.12 , which is shown as Fig. 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 With 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 With λ s The product of is greater than ν ss , but f p With 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 With 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. Fig.11 It can be seen that the Q value of the corresponding frequency is almost 0.

[0104] See also Fig.13 , which is shown as Fig. 9 The corresponding 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 With λ s The product of is less than v ss , the main mode hardly leaks to the supporting substrate 3. s For 1.00μm and 1.05μm, f H With λ s The product of is greater than v ss , but f p With 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 1.10 μm,p With 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. Fig.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 Fig.14 , which shows the frequency response of the first high-order acoustic wave filter of the present application, which is Figure 7 The difference is that Fig.14 The λ of the series resonator of the high-order acoustic wave filter s It is 0.95μm. From the S21 curve, it can be seen that 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 Fig.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 Fig.15 The top electrode spacing of the series resonator of the high-order acoustic wave filter is 6 λ s is 1.00μm. From the S21 curve, it can be seen that the LL-SAW mode of series resonator 1 is Fig.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 Fig.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 Fig.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 Fig.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, and the filter passband performance is similar to Figure 7 Still almost no difference.

[0108] See also Fig.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 Fig.17 The top electrode 6 spacing of the series resonator of the high-order acoustic wave filter is λ s is 1.10μm. From the S21 curve, it can be seen that the LL-SAW mode of series resonator 1 is Fig.16 Further decline, and has begun to move away from zero, relative to Fig.14 The out-of-band suppression level of this frequency has been reduced. 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 Figure 7 Significant increase.

[0109] See also Fig.18 , which is shown as Figure 7 and Fig.16 From the comparison of the S21 curve in , we can see that when λ s When the frequency of the series resonator 1 is greater than f H The loss in the frequency band increases, and the parasitic response caused by the S1 mode of parallel resonator 2 is greatly reduced. For further information, please refer to Fig.19 , which is shown as Fig.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 Fig. 20 , which is shown as Figure 7 and Fig.17 From the comparison of the S21 curve in , we can see that when λ s When the transition band is 1.10μm, the flatness of the transition band and the out-of-band suppression are improved. For further information, please refer to Fig.21 , which is shown as Fig. 20 The local enlarged diagram 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 satisfy f H <v fs / λ s Under the premise of flexibly selecting the 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 parasitic response caused by the S1 mode of parallel resonator 2 is also greatly weakened.

[0112] A set of parallel resonators 2 is also provided, which corresponds to Figure 4 The structure shown in FIG. 1 shows that the difference between the resonators in the group of resonators 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 is 12484m / 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; the top electrode 6 is 50nm chromium, and the main mode is the SH1 mode. Specifically, the group of parallel resonators 2 includes 5 resonators, and the λ of these 5 resonators is p They are 1.00 μm, 1.05 μm, 1.10 μm, and 1.15 μm respectively. In order to ensure the same resonance frequency, the corresponding thicknesses of the piezoelectric film 5 are 223 nm, 216 nm, 210 nm, and 204 nm respectively. That is, λ p The smaller the thickness of the corresponding piezoelectric film 5 is, the thicker it is. Fig. 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 increase with λ p For example, λ p When f is 1.00μm and 1.05μm, H With λ p The product of is greater than v ss , but f H With 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 overlap within the filter passband frequency range. p When the filter is 1.10μm and 1.15μm, the upper cutoff frequency f H With λp The product of is greater than the fast shear wave speed ν of the supporting substrate 3 fs , so the admittance curve is similar to λ in the passband frequency range. p =1.00μm, there is no overlap.

[0113] See also Fig.23 , which is shown as Fig. 22 Corresponding to the conductivity curve, it can be seen that λ p The conductivity curves corresponding to 1.00-1.05μm almost overlap within the filter passband frequency range. p When f H The conductance values ​​nearby increase, which indicates an increase in losses at the corresponding frequency.

[0114] See also Fig.24 , which is shown as Fig. 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 Fig.25 , which is shown as Fig. 22 The corresponding vibration mode diagram of each resonator near the cutoff frequency of the filter is taken at a frequency of 7125MHz. p For 1.00μm and 1.05μm, f H With λ p The product of is greater than v ss , but f p With 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 f is 1.10μm and 1.15μm, p With 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. Fig.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 Fig.26 , which shows the frequency response of the fifth high-order acoustic wave filter of the present application, and Fig.16 The difference is that Fig.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 since the S1 mode of the parallel resonator 2 is smaller than λ p When it is 1.00μm, it is weakened, and 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, and the filter passband performance is similar to Figure 7 Almost no deterioration in comparison.

[0117] See also Fig. 27 , which shows the frequency response of the sixth high-order acoustic wave filter of the present application, and Fig.16 The difference is that Fig. 27 The λ of the parallel resonator of the high-order acoustic wave filter p is 1.10μm. From the S21 curve, it can be seen that the LL-SAW mode of series resonator 1 is Fig.26 Further decline, and has begun to move away from zero, relative to Fig.26 The out-of-band suppression level of this frequency has been reduced. 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 Fig.26 Significant increase.

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

[0119] See also Fig.29 , which is shown as an exemplary embodiment of the present application Fig.26 and Fig.16 The comparison of the S21 curves shows that when λ p When the frequency is 1.05 μm, the out-of-band suppression level of the corresponding frequency is further improved due to the weakening of the S1 mode of parallel resonator 2. For further information, please refer to Fig.30 , which is shown as Fig.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 since the longitudinal mode frequency of the LL-SAW of the parallel resonator 2 is reduced to outside the passband, the in-band flatness of the filter is significantly improved.

[0120] See also Fig.31 , which shows the S21 curve of the eighth high-order acoustic wave filter of the present application and Fig.26 The comparison of S21 curves is shown in Figure 2. Fig.26 The corresponding high-order acoustic wave filter has a parallel resonator 2 composed of λ p By replacing the resonator with =1.10μm, 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 increase 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] The present application also discloses a communication device on the other hand, which includes the above-mentioned high-order acoustic wave filter. Communication devices are usually devices used to transmit information. They can transmit information in a wired or wireless manner. Therefore, communication devices can be divided into wired communication devices and wireless communication devices according to the information transmission method. Among them, wired communication devices can be computers, televisions, telephones, PCMs, optical transceivers, servers, etc. Wireless communication devices can be satellites, radio stations, wireless televisions (on buses or subways), wireless local area networks, mobile phones (cell phones), etc.

[0123] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope 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 the first parameter condition, and at least one resonator in the high-order acoustic wave filter satisfies 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 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 sound velocity of the supporting substrate.

2. The high-order acoustic wave filter according to claim 1, characterized in that: A product of an electrode finger pitch of the series resonator and an antiresonance frequency of the series resonator is greater than a slow shear wave acoustic velocity of the support substrate.

3. The high-order acoustic wave filter according to claim 1, characterized in that: 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.

4. The high-order acoustic wave filter according to claim 1, characterized in that: The first parameter condition also includes: The product of the electrode finger spacing of the resonator and the upper cutoff frequency of the high-order acoustic wave filter is smaller than the fast shear wave sound velocity of the supporting substrate.

5. The high-order acoustic wave filter according to claim 1, characterized in that: 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.

6. The high-order acoustic wave filter according to claim 1, characterized in that: 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.

7. The high-order acoustic wave filter according to any one of claims 1 to 6, characterized in that: A dielectric layer is also 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.

8. The high-order acoustic wave filter according to claim 1, characterized in that: 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 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 cut shapes.

9. The high-order acoustic wave filter according to claim 1, characterized in that: The support substrate comprises 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.

10. The high-order acoustic wave filter according to claim 1, characterized in that: 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.

11. The high-order acoustic wave filter according to claim 10, characterized in that: 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 is in contact with 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 a plurality of electrode fingers in the interdigitated electrode overlap in an interlaced manner.

12. The high-order acoustic wave filter according to claim 1, characterized in that: The duty ratio, 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.

13. The high-order acoustic wave filter according to claim 1, characterized in that: 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.

14. The high-order acoustic wave filter according to claim 1, characterized in that: 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.

15. The high-order acoustic wave filter according to claim 1, characterized in that: 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 of the electrode finger spacing.

16. A communication device, characterized in that: Comprising a high-order acoustic wave filter as described in any one of claims 1-15.

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