Elastic wave resonator and its communication device

Abstract

The present invention provides an elastic wave resonator and its communication device, comprising interdigitated electrodes, a piezoelectric film, a suspended electrode, and a filler material. By replacing some of the suspended electrodes with the filler material, or placing different fillers near the suspended electrodes, and selectively adjusting the line width of the suspended electrodes, the frequency or displacement distribution of parasitic modes that vibrate outside the longitudinal electric field is altered, thereby removing or completely suppressing these parasitic modes. This solution, an optimization without changing the piezoelectric film structure, facilitates structural stability and enables large-scale manufacturing of high-performance, high-frequency, wide-bandwidth acoustic wave filters.

Description

Technical Field

[0001] The invention belongs to the field of microelectronic devices and relates to an elastic wave resonator and a communication device thereof. Background Art

[0002] RF front-end modules are a crucial component for mobile terminal communications. Bandpass filters are core components responsible for signal transmission and reception, allowing only signals of specific frequencies to pass. To meet the signal-to-noise ratio requirements of communication systems and protocols, filter performance requirements for passband flatness, in-band insertion loss, bandedge steepness, rectangularity, and out-of-band rejection are becoming increasingly stringent. Elastic wave filters, with their small size and simple process, play a crucial role in RF front-end components.

[0003] Elastic wave filter technology is currently the most widely used RF filter technology, mainly including bulk acoustic wave (BAW), surface acoustic wave (SAW) filter technology, and plate wave (Plate Wave) filter technology based on single crystal piezoelectric film. Among them, the high-order acoustic wave mode excited by the longitudinal electric field has great advantages in frequency, bandwidth, and capacitance density. However, due to the multiple non-zero piezoelectric coefficients of piezoelectric materials and the existence of areas of acoustic impedance discontinuity in the resonator, different types of parasitic modes will appear near the main mode. These parasitic modes will cause fluctuations in the filter passband or a decrease in the out-of-band suppression level of the corresponding frequency band. Therefore, suppressing various types of parasitic modes or transferring parasitic modes to frequency bands with low requirements for out-of-band suppression will help to achieve high-performance RF filters with low loss, large bandwidth, high frequency, high out-of-band suppression and flat passband.

[0004] In prior art 1, reference Figure 1 , by cutting grooves between the top electrodes 11, parasitic modes excited by the transverse electric field are suppressed. This scheme targets the thickness shear mode, which is excited by the longitudinal electric field and has vibrations concentrated between the top electrode 11 and the bottom electrode 12. By etching away the piezoelectric film 13 between the top electrodes 11, the area through which the transverse electric field passes can be reduced, suppressing parasitic modes excited by the transverse electric field, but this also makes the resonator structure more fragile.

[0005] In another prior art 2, referring to Figure 2, by completely embedding the interdigital electrodes 21, the higher harmonics in the horizontal propagation direction are suppressed. This solution utilizes the high-order modes excited by the horizontal electric field. The displacement of the mode is concentrated in the area between the interdigital electrodes 21. By making the acoustic impedance of the electrode-covered area equal to that of the non-electrode-covered area, the higher harmonics in the horizontal direction can be suppressed. This requires that the interdigital electrodes 21 be completely embedded in the piezoelectric film LiNbO3 22. However, the disadvantage of this solution is that the side walls of the embedded interdigital electrodes 21 are difficult to perfectly fit the side walls of the etched grooves in the piezoelectric film 22, and the target mode is excited by the lateral electric field, which will lead to a decrease in the performance of the resonator.

[0006] Therefore, in view of the shortcomings of the above solutions, how to provide an elastic wave resonator that, while ensuring structural stability, does not change the electric field distribution and other performance of the resonator, and can suppress various types of parasitic modes or transfer the parasitic modes to frequency bands where out-of-band suppression requirements are not high, and obtain a high-performance RF filter with low loss, wide bandwidth, high frequency, high out-of-band suppression and flat passband, has become an important technical problem that needs to be urgently solved by those skilled in the art.

[0007] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the object of the present invention is to provide an elastic wave resonator and a communication device thereof, which are used to solve the problem of how to suppress high-order harmonics and other parasitic modes with similar frequencies in the acoustic wave mode excited by the longitudinal electric field of the existing elastic wave resonator.

[0009] To achieve the above-mentioned and other related purposes, the present invention provides an elastic wave resonator, which comprises

[0010] Interdigitated electrodes, piezoelectric films, suspended electrodes, and filling materials;

[0011] The piezoelectric film has a first surface and a second surface;

[0012] The interdigital electrodes are located on the first surface of the piezoelectric film and include an interdigital electrode pair and an interdigital electrode gap region;

[0013] The suspension electrode is located on the second surface of the piezoelectric film and contacts the piezoelectric film. The suspension electrode and the interdigitated electrodes are correspondingly arranged to form a longitudinal electric field region, and the potential of each position of the suspension electrode is the same.

[0014] The filling material is located on the second surface of the piezoelectric film and contacts the suspension electrode. The vertical projection of the filling material is at least located in the non-longitudinal electric field region, so that the filling material can suppress the parasitic mode or keep the parasitic mode away from the target mode.

[0015] The target mode is the acoustic wave mode excited by the high-frequency acoustic wave resonator under the action of the longitudinal electric field.

[0016] Optionally, the filling material and the suspension electrodes are distributed alternately, and the filling material includes a single layer or a composite laminate.

[0017] Optionally, the filling material corresponding to the suspension electrode is further provided on a side of the suspension electrode away from the piezoelectric film, and the filling material is distributed in intervals or in a whole layer.

[0018] Optionally, the levitation electrodes are distributed in layers, and the filling materials are all located below the levitation electrodes, and the filling materials are distributed alternately; and the filling materials include a single layer or a composite laminate.

[0019] Optionally, the filling material includes one or more combinations of silicon oxide, aluminum oxide, zinc oxide, chromium, nickel, silicon, titanium, copper, aluminum, boron, molybdenum, tungsten, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

[0020] Optionally, the filling material includes a conductive material with a conductivity of ≥50S / m.

[0021] Optionally, the interdigitated electrodes are top electrodes, and the corresponding floating electrodes are bottom electrodes; or the interdigitated electrodes are bottom electrodes, and the corresponding floating electrodes are top electrodes.

[0022] Optionally, a supporting substrate is further provided below the bottom electrode; and the filling material is further provided below the area where the suspension electrode and the filling material are alternately distributed and is distributed in a whole layer.

[0023] The supporting substrate includes one of a high acoustic velocity supporting layer, a first substrate layer or a second substrate layer;

[0024] The first substrate layer includes a stacked support layer and a high acoustic velocity layer;

[0025] The second substrate layer includes a stacked support layer and a Bragg reflection layer.

[0026] Optionally, a dielectric layer is further included between the bottom electrode and the supporting substrate, and the dielectric layer includes a combination of one or more layers of a silicon oxide layer, a silicon nitride layer, a polysilicon layer, an amorphous silicon layer, an aluminum oxide layer, and an aluminum nitride layer.

[0027] The present invention also provides a communication device, which includes at least one of a filter, a duplexer, and a multiplexer.

[0028] As described above, the present invention provides an elastic wave resonator and its communication device. On the one hand, it is based on the principle that when the target mode is an acoustic wave mode excited by a longitudinal electric field, its vibration is mainly concentrated between the top electrode and the bottom electrode, and the adjustment of the area outside the longitudinal electric field has almost no effect on the main mode. In the non-longitudinal electric field area, the present application uses a filling material to replace part of the floating electrode, or sets different filling materials near the floating electrode, and selectively sets the floating electrode line width to change the frequency or displacement distribution of the parasitic mode outside the longitudinal electric field, thereby achieving the purpose of removing the parasitic mode or completely suppressing the parasitic mode. On the other hand, by optimizing the electric potential of the entire floating electrode to be the same, a wider range of filling materials can be selected without causing the generation of other parasitic capacitances. At the same time, the present technical solution is an optimization solution based on the piezoelectric film structure without changing the structure, which is more conducive to structural stability and large-scale production of high-performance, high-frequency, and wide-bandwidth acoustic wave filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It shows a schematic diagram of the structure of an elastic wave device in prior art 1 that suppresses parasitic modes by cutting grooves between interdigitated top electrodes.

[0030] Figure 2 It shows a schematic diagram of the structure of an elastic wave device in the prior art 2 that suppresses parasitic modes by embedding electrodes.

[0031] Figure 3 Shown is a schematic structural diagram of the elastic wave device in comparative example 1.

[0032] Figure 4 Display as Figure 3 The simulated admittance curve corresponding to the structure shown.

[0033] Figure 5 It shows a schematic structural diagram of the elastic wave device in comparative example 2.

[0034] Figure 6 Display as Figure 5 The simulated admittance curve corresponding to the structure shown.

[0035] Figure 7 Shown is a schematic structural diagram of the elastic wave device in comparative example three.

[0036] Figure 8 Display as Figure 7 The simulated admittance curve corresponding to the structure shown.

[0037] Figure 9Shown is a schematic structural diagram of the elastic wave device in comparative example four.

[0038] Figure 10 Display as Figure 9 The simulated admittance curve corresponding to the structure shown.

[0039] Figure 11 It shows a schematic structural diagram of the elastic wave device in comparative example five.

[0040] Figure 12 Display as Figure 11 The simulated admittance curve corresponding to the structure shown.

[0041] Figure 13 Shown are schematic structural diagrams of the elastic wave devices in the first and second embodiments.

[0042] Figure 14 Shown is a top view of an IDT.

[0043] Figure 15 Display as Figure 13 The simulated admittance curve corresponding to the structure shown when the filling material is insulating aluminum oxide.

[0044] Figure 16 Display as Figure 13 The simulated admittance curve corresponding to the structure shown when the filling material is conductive aluminum oxide.

[0045] Figure 17 Display as Figure 13 Schematic diagram of the resonator structure with the top electrode being a suspended electrode and the bottom electrode being an interdigitated electrode.

[0046] Figure 18 Display as Figure 17 The simulated admittance curve corresponding to the structure shown.

[0047] Figure 19 Display as Figure 13 Schematic diagram of the elastic wave device structure with a composite stack of filling materials and suspended electrodes distributed alternately.

[0048] Figure 20 Display as Figure 19 The simulated admittance curve corresponding to the structure shown.

[0049] Figure 21 The diagram shows the structure of an elastic wave device in which the filling materials are all located below the floating electrodes and are distributed alternately.

[0050] Figure 22 Schematic diagram of the elastic wave device structure showing alternating distribution of filling material and suspended electrodes, with another filling material located below the suspended electrodes.

[0051] Figure 23 A schematic diagram of the elastic wave device structure is shown, in which one filling material and a suspended electrode are superimposed and another filling material is distributed alternately.

[0052] Figure 24 Display as Figure 13 Schematic diagram of the elastic wave device structure with a high acoustic velocity support layer added to the structural basis.

[0053] Figure 25 Display as Figure 23 Schematic diagram of the elastic wave device structure with a high acoustic velocity support layer added to the structural basis.

[0054] Figure 26 Display as Figure 13 Schematic diagram of the elastic wave device structure with a first substrate layer and a dielectric layer added to the structure.

[0055] Figure 27 Display as Figure 13 Schematic diagram of the elastic wave device structure with a second substrate layer added to the structural basis.

[0056] Figure 28 Display as Figure 3 Schematic diagram of the elastic wave device structure with a first substrate layer and a dielectric layer added to the structural contact.

[0057] Figure 29 Display as Figure 28 The simulated admittance curve corresponding to the structure shown.

[0058] Figure 30 Display as Figure 24 Schematic diagram of the elastic wave device structure with a dielectric layer added to the structural basis.

[0059] Figure 31 Display as Figure 30 The simulated admittance curve corresponding to the structure shown when the filling material is copper.

[0060] Figure 32 Display as Figure 30 Comparison of simulated admittance curves corresponding to various filling materials in the structure shown.

[0061] Description of Reference Numerals

[0062] 11 Top electrode

[0063] 12 bottom electrode

[0064] 13 Piezoelectric film

[0065] 21 interdigitated electrodes

[0066] 22 Piezoelectric film LiNbO3

[0067] 100 interdigitated electrodes

[0068] 101 Upper interdigital electrode

[0069] 102 Lower interdigital electrode

[0070] 200 Piezoelectric Film

[0071] 300 Suspended Electrode

[0072] 400 Filling material

[0073] 401 First filling material

[0074] 402 Second filling material

[0075] 500 interdigitated electrode pairs

[0076] 501 First Bus

[0077] 502 Second bus

[0078] 503 first interdigital electrode

[0079] 504 second interdigital electrode

[0080] 505 aperture area

[0081] 506 interdigitated electrode gaps

[0082] 507 Interdigital Transducer Air Gap

[0083] 600 high-sonic support layer

[0084] 700 dielectric layer

[0085] 800 first substrate layer

[0086] 801 High Sound Velocity Layer

[0087] 802 stacked support layers

[0088] 900 Bragg reflector

[0089] 1000 Second substrate layer DETAILED DESCRIPTION

[0090] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0091] For example, when describing the embodiments of the present invention, cross-sectional views of device structures may be partially enlarged to scale for ease of explanation. Furthermore, these schematic views are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual manufacturing, three-dimensional dimensions, including length, width, and depth, should be included.

[0092] For convenience of description, spatially relative terms such as "under," "below," "below," "below," "over," and the like may be used herein to describe the relationship of one element or feature to other elements or features illustrated in the drawings. It will be understood that these spatially relative terms are intended to encompass orientations of the device in use or operation in addition to the orientation depicted in the drawings, and may include embodiments in which the first and second features are formed in direct contact, as well as embodiments in which additional features are formed between the first and second features so that the first and second features may not be in direct contact. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0093] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0094] The following is an explanation of the abbreviations of the nouns involved below.

[0095] LL-SAW:Longitudinal leaky SAW longitudinal leakage surface acoustic wave

[0096] SH1:First-order shear horizontal mode

[0097] S1:First-order symmetric Lamb wave mode

[0098] A1: First-order antisymmetric Lamb wave mode

[0099] Comparative Example 1

[0100] See Figure 3An elastic wave device is provided, comprising an interdigital electrode 100, a piezoelectric film 200, and a floating electrode 300 stacked from top to bottom. The interdigital electrode 100 serves as the top electrode, and the floating electrode 300 serves as the bottom electrode. The interdigital electrodes 100 include a first interdigital electrode and a second interdigital electrode, each extending perpendicular to the direction of acoustic wave propagation. The center-to-center spacing between adjacent electrode fingers of the first interdigital electrode and the center-to-center spacing between adjacent electrode fingers of the second interdigital electrode are both λ.

[0101] Figure 4 Display as Figure 3 The simulated admittance curve corresponding to the structure shown is shown. The top interdigital electrode 100 is aluminum, 50 nm thick, with a λ of 2.9 μm and a line width W1 of 1015 nm. The bottom floating electrode 300 is aluminum, 50 nm thick. The piezoelectric film 200 is Y171-cut lithium niobate, 300 nm thick. The dominant mode for this structure is the A1 mode.

[0102] from Figure 4 As can be seen in the figure, the piezoelectric coefficient components in the piezoelectric film 200 that are unrelated to the main mode lead to the existence of parasitic modes. These parasitic modes contain horizontal harmonics of the 0th-order mode, such as the LL-SAW mode, near the antiresonance frequency of the main mode and at frequencies higher than the main mode. These parasitic modes will cause the filter's passband fluctuations or reduce the out-of-band rejection level.

[0103] Comparative Example 2

[0104] See Figure 5 , provides a cross-sectional view of a comparative elastic wave resonator, comprising interdigitated electrodes 100, a piezoelectric film 200, and a suspended electrode 300. The interdigitated electrodes 100 have a line width of W1. The difference from Comparative Example 1 is that the suspended electrodes 300 are replaced by discrete fingers, all of which have the same potential, and the discrete fingers of the suspended electrodes 300 have a width of W2.

[0105] Figure 6 Display as Figure 5 The simulated admittance curve corresponding to the structure shown in the figure is: the interdigitated electrode 100 at the top is made of aluminum, with a thickness of 50nm, λ is 2.9μm, and W1 is 1015nm. The floating electrode 300 at the bottom is made of aluminum, with a thickness of 50nm, and a width W2 of 870nm. The piezoelectric film 200 is made of Y171-cut lithium niobate with a thickness of 300nm. The main mode is A1 mode. Therefore, Figure 6 It can be seen from FIG. 1 that changing the structure of the floating electrode 300 to discrete fingers has no significant effect on suppressing the parasitic mode LL-SAW.

[0106] Comparative Example 3

[0107] See Figure 7 A cross-sectional view of a comparative elastic wave resonator is provided, comprising an upper interdigital electrode 101, a piezoelectric film 200, and a lower interdigital electrode 102. The difference from Comparative Example 2 is that the floating electrode 300 is replaced by the lower interdigital electrode 102. Adjacent upper interdigital electrodes 101 and lower interdigital electrodes 102 have opposite potentials, and adjacent lower interdigital electrodes 102 have opposite potentials. The electrodes on either side of the piezoelectric film 200 at the same location have opposite potentials. The upper interdigital electrode has a line width of W1, and the lower interdigital electrode has a line width of W2.

[0108] Figure 8 Display as Figure 7 The simulated admittance curve corresponding to the structure shown in the figure, wherein the top interdigital electrode 101 is aluminum, with a thickness of 50nm, λ is 2.9μm, and the interdigital electrode line width W1 is 1015nm. The bottom interdigital electrode 102 is aluminum, with a thickness of 50nm, and the electrode width W2 is 870nm. The piezoelectric film is Y171-cut lithium niobate with a thickness of 300nm. The main mode is A1 mode. Therefore, from Figure 8 It can be seen from FIG that changing the structure of the floating electrode 300 to an interdigitated electrode has no significant effect on suppressing the parasitic mode LL-SAW.

[0109] Comparative Example 4

[0110] See Figure 9 , provides a cross-sectional view of a comparative elastic wave resonator, comprising interdigitated electrodes 100, a piezoelectric film 200, and a suspended electrode 300 at the top, along with a filler material 400 between the interdigitated electrodes 100. The interdigitated electrodes 100 serve as the top electrode, and the suspended electrode 300 serves as the bottom electrode. The difference from Comparative Example 1 is that the interdigitated electrodes 100 are filled with the filler material 400, and the interdigitated electrodes 100 have a line width of W1.

[0111] Figure 10 Display as Figure 9 The corresponding simulated admittance curve is shown in the figure. The interdigital electrode 100 at the top is made of aluminum with a thickness of 50nm, λ is 2.9μm, and the line width W1 of the interdigital electrode 100 is 1015nm. The floating electrode 300 at the bottom is made of aluminum with a thickness of 50nm. The piezoelectric film 200 is made of Y171-cut lithium niobate with a thickness of 300nm. The filling material 400 is aluminum oxide. The main mode is A1 mode. Therefore, Figure 10 It can be seen from the figure that the suppression of the parasitic mode LL-SAW by setting the filling material in the interdigital electrodes is not significant.

[0112] Comparative Example 5

[0113] See Figure 11, provides a cross-sectional view of a comparative elastic wave resonator, including the top interdigital electrode 100, the piezoelectric film 200 and the suspension electrode 300 and the filling material 400 between the top interdigital electrodes 100. Figure 9 The difference is that the floating electrode 300 is replaced by discrete fingers, and the potential of the floating electrodes 300 is the same. The interdigitated electrode 100 is the top electrode, and the floating electrode 300 is the bottom electrode. The interdigitated electrode 100 has a line width of W1, while the discrete fingers of the floating electrode 300 have a width of W2.

[0114] Figure 12 Display as Figure 11 Corresponding simulated admittance curve: The top interdigital electrode 100 is made of aluminum, with a thickness of 50 nm, a λ of 2.9 μm, and a line width W1 of 1015 nm. The piezoelectric film 200 is Y171-cut lithium niobate, with a thickness of 300 nm. The bottom floating electrode 300 is made of aluminum, with a thickness of 50 nm, and an electrode width W2 of 870 nm. The filler material 400 is aluminum oxide. The main mode is the A1 mode.

[0115] from Figure 12 It can be seen from the figure that changing the structure of the floating electrode 300 into discrete fingers and providing a filling material 400 in the interdigitated electrodes 100 does not significantly suppress the parasitic mode LL-SAW.

[0116] As can be seen from the implementation results of Comparative Examples 1 to 5, when the corresponding materials, dimensions, etc. of the resonator structure remain unchanged, the overall effect of suppressing the parasitic LL-SAW mode near the antiresonance frequency by changing the floating electrodes to discrete fingers, changing the floating electrodes to interdigitated electrodes, and providing the interdigitated electrode filling material is not significant. The following Examples 1 to 3 illustrate the technical solutions and technical effects of the present application relative to Comparative Examples 1 to 5.

[0117] Example 1

[0118] See Figure 13 , provides a cross-sectional view of an elastic wave resonator, including an interdigitated electrode 100, a piezoelectric film 200, a bottom suspended electrode 300, and a filling material 400. The morphology of the interdigitated electrode 100 can be found in the following relevant Figure 14As described above, in this embodiment, the levitation electrodes 300 are arranged correspondingly to the interdigitated electrodes 100. The levitation electrodes 300 are arranged in an interspaced pattern, and each levitation electrode 300 has the same potential. The filler material 400 is located between the levitation electrodes 300 and is distributed alternately with the levitation electrodes 300 in a layered pattern. The interdigitated electrodes 100 are top electrodes, and the levitation electrodes 300 are bottom electrodes. The interdigitated electrodes 100 have a line width of W1, and the levitation electrodes have a width of W2. The levitation electrodes 300 are arranged correspondingly to the interdigitated electrodes 100 to provide a longitudinal electric field, and their centers coincide with each other. The vertical projections of the gaps between the filler material 400 and the interdigitated electrodes 100 coincide with each other. In other embodiments, the center positions of the floating electrode 300 and the interdigital electrodes 100 may also be offset, as long as both can provide a longitudinal electric field. Preferably, the ratio of the center offset between the floating electrode 300 and the interdigital electrodes 100 to the width W1 of the interdigital electrodes is ≤20%. Similarly, the ratio of the vertical projection center offset between the filling material 400 and the interdigital electrode gap region to the width W1 of the interdigital electrodes is ≤20%.

[0119] Figure 14 The diagram shows a top view of an IDT. The IDT includes a first bus bar 501, a second bus bar 502, the interdigital electrode pair 500, an interdigital electrode gap 506, and an IDT air gap 507. The interdigital electrode pair 500 includes a first interdigital electrode 503 and a second interdigital electrode 504. The interdigital electrodes extend perpendicular to the direction of acoustic wave propagation. The first interdigital electrode 503 is connected to the first bus bar 501, and the second interdigital electrode 504 is connected to the second bus bar 502. The center-to-center spacing between adjacent electrode fingers of the first interdigital electrode 503 and the center-to-center spacing between adjacent electrode fingers of the second interdigital electrode 504 are both λ. The interdigital electrode pair 500 and the interdigital electrode gap 506 form an aperture region 505. The width of the floating electrode 300 in the direction of the interdigital electrodes does not exceed the length of the aperture region 505, which is the length of the aperture region in the direction of the interdigital electrodes.

[0120] Figure 15 Display as Figure 13 Corresponding simulated admittance curve: The interdigital electrodes 100 are made of aluminum, with a line width W1 of 1015 nm, a thickness of 50 nm, and a λ of 2.9 μm. The bottom floating electrode 300 is made of aluminum, with a thickness of 50 nm and an electrode width W2 of 870 nm. The potential at each position of the floating electrode is the same. The piezoelectric film 200 is Y171-cut lithium niobate, with a thickness of 300 nm. The filler material 400 is insulating aluminum oxide. The main mode is the A1 mode.

[0121] from Figure 15 As can be seen, although parasitic modes near the positive resonant frequency still exist, those near the antiresonant frequency are weakened. In this embodiment, to illustrate the inhibitory effect of insulating alumina as the filler material 400 on parasitic modes near the antiresonant frequency, the dimensions of the interdigital electrodes, floating electrodes, and piezoelectric film of the resonator remain unchanged from those in Comparative Example 1.

[0122] This solution does not form grooves in the piezoelectric film, ensuring structural stability compared to prior art 1. Furthermore, in the target mode excited by the longitudinal electric field, vibration is concentrated between the top and bottom electrodes. This embodiment does not employ an embedded electrode structure, while other resonator performance is unaffected. Furthermore, the equipotential arrangement of the suspended electrodes prevents the addition of parasitic capacitance in the longitudinal electric field region, thereby reducing the electromechanical coupling coefficient of the target mode.

[0123] In some other embodiments, the interdigitated electrodes, suspended electrodes and conductive filling materials can be a combination of 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.

[0124] In another exemplary embodiment, by further optimizing the width of the interdigital electrode line width W1 and the suspension electrode line width W2, the parasitic mode corresponding to the longitudinal electric field target mode is suppressed when the integral of the stress and electric field product in the piezoelectric film region is zero. In Example 1, due to the different potentials of the underlying suspension electrode and the insulating aluminum oxide, the non-longitudinal electric field undergoes a significant change relative to the electric field in Comparative Example 1 after the bottom layer is filled with insulating aluminum oxide. Simply filling with insulating aluminum oxide cannot completely suppress the parasitic mode. However, by providing the insulating aluminum oxide filling material and optimizing the interdigital electrode line width W1 and the suspension electrode line width W2, not only the parasitic modes near the antiresonance frequency are significantly suppressed, but also the parasitic modes near the positive resonant frequency are significantly suppressed. The admittance curve after adjusting the line width is not presented here. The electromechanical coupling coefficient can be calculated by integrating the stress and electric field. The electromechanical coupling coefficient reflects the cumulative effect of the interaction between stress and electric field within the material volume of the piezoelectric film region. When the electromechanical coupling coefficient of the parasitic mode is 0, the parasitic peak disappears in the admittance curve, thereby suppressing the parasitic mode. In the embodiment described above, the frequency of the parasitic mode acoustic wave is changed by setting the filling material and affecting the stress distribution in the non-longitudinal electric field area, and the electric field distribution in the non-longitudinal electric field is changed by adjusting the electrode line width, thereby optimizing the presence of the stress T and electric field E components to minimize the integral of T and E of the parasitic mode on the piezoelectric film area, so that the parasitic mode LL-SAW is suppressed. In order to conceptually explain the principle of minimizing the electromechanical coupling of the parasitic mode, the electromechanical coupling coefficient k is used here.t 2 The definition formula is:

[0125]

[0126] Among them, k t 2 The parameter representing the electromechanical coupling effect during mode vibration reflects the energy conversion efficiency when the thin film is polarized along the thickness direction and electrically excited to perform stretching vibration in the thickness direction. m represents the interaction energy, U e Represents electrical energy, U d Represents mechanical energy. T represents stress tensor, and E represents electric field vector. d, s E , ε T where represents the piezoelectric strain constant, the compliance constant under a constant electric field, and the dielectric constant under a constant stress, respectively. dv represents the volume element. The techniques employed in the described embodiments optimize the presence of stress T and electric field E components in the non-longitudinal electric field region to minimize the parasitic mode integrals T and E in the piezoelectric film region. Consequently, the interaction energy in the piezoelectric film is reduced to near zero, thereby suppressing the parasitic modes.

[0127] Example 2

[0128] Based on the structure of the first embodiment, the resonator structure is as follows: Figure 13 As shown, the structure remains unchanged, and the filling material 400 is changed from insulating aluminum oxide to conductive aluminum oxide. In this embodiment, the suspension electrodes 300 are arranged corresponding to the interdigitated electrodes 100, the suspension electrodes 300 are spaced apart, and each suspension electrode 300 has the same potential.

[0129] Figure 16 The figure shows a simulated admittance curve corresponding to Example 2, wherein the interdigitated electrode 100 is made of aluminum, has a line width W1 of 1015 nm, a thickness of 50 nm, and a λ of 2.9 μm. The suspended electrode 300 is made of aluminum, has a thickness of 50 nm, and an electrode width W2 of 870 nm. The potential at each position of the suspended electrode is the same. The piezoelectric film 200 is made of Y171-cut lithium niobate, with a thickness of 300 nm. The interdigitated electrode 100 is the top electrode, and the suspended electrode 300 is the bottom electrode. The filling material 400 is conductive aluminum oxide and is distributed alternately with the suspended electrode, with the main mode being the A1 mode. Preferably, the conductivity of the conductive aluminum oxide is ≥50 S / m.

[0130] from Figure 16As can be seen in the figure, parasitic modes are largely suppressed across a wide frequency range without sacrificing the frequency and electromechanical coupling coefficient of the main mode. Since the vibration of the main mode A1 is primarily concentrated between the top and bottom electrodes, replacing a portion of the suspended electrode in the non-longitudinal electric field region, where the main mode A1 vibration is weaker, has little impact on the main mode. The replacement conductive alumina has the same potential as the bottom suspended electrode, and does not alter the non-longitudinal electric field distribution before replacement. Instead, it reduces the electromechanical coupling coefficient by altering the stress distribution in the non-longitudinal electric field, thereby achieving the goal of suppressing parasitic modes.

[0131] It should be noted that the above embodiments 1 and 2 both use the interdigital electrodes as the top electrodes and the floating electrodes as the bottom electrodes, but this is not limited to this. As required, the floating electrodes can also be used as the top electrodes and the interdigital electrodes as the bottom electrodes. Figure 17 The resonator structure comprises a floating electrode 300 serving as the top electrode and an interdigitated electrode 100 serving as the bottom electrode. The floating electrodes 300 are disposed correspondingly to the interdigitated electrodes 100, and each of the floating electrodes 300 has the same potential. The filler material 400 is conductive aluminum oxide and is distributed in layers, alternating with the floating electrodes 300.

[0132] Figure 18 Display as Figure 17 The simulated admittance curve of the corresponding structure is different in that the interdigitated electrodes 100 serve as the bottom electrode, the floating electrode 300 serves as the top electrode, and the filling material 400 and the floating electrode 300 are distributed alternately, which can also achieve the purpose of suppressing parasitic modes.

[0133] Example 3

[0134] In order to overcome the difficult process problem of preparing the conductive aluminum oxide, the resonator can also be made of Figure 19 The resonator structure shown, Figure 19 The structure includes interdigitated electrodes 100, a piezoelectric film 200, a levitating electrode 300, and a first filler material 401 and a second filler material 402. The levitating electrodes 300 are arranged corresponding to the interdigitated electrodes 100, are spaced apart, and each levitating electrode 300 has the same potential. The first filler material and the second filler material are distributed in layers. Furthermore, the first filler material 401 and the second filler material 402 are laminated and alternately distributed with the levitating electrodes 300. The interdigitated electrodes 100 serve as the top electrode, and the levitating electrodes 300 serve as the bottom electrode.

[0135] Figure 20 Display as Figure 19Simulated admittance curve corresponding to the structure. The interdigitated electrodes 100 are made of aluminum, with a line width W1 of 1015 nm, a thickness of 50 nm, and a λ of 2.9 μm. The suspended electrodes 300 are made of aluminum, with a thickness of 50 nm and an electrode width W2 of 870 nm. The potential at each position of the suspended electrodes 300 is the same. The piezoelectric film 200 is made of Y171-cut lithium niobate, with a thickness of 300 nm. The first filler material 401 is aluminum, and the second filler material 402 is insulating aluminum oxide. The thickness of the first filler material 401 is 1 nm, and the dominant mode is the A1 mode.

[0136] from Figure 20 As can be seen from the figure, the parasitic mode LL-SAW is suppressed, similar to the results in Example 2. To provide the same potential as the floating electrode 300, a thin layer of the first filling material 401 is provided to ensure that the non-longitudinal electric field does not change significantly before and after the insulating aluminum oxide layer is filled.

[0137] In another exemplary embodiment, referring to Figure 21 The resonator structure may further include interdigitated electrodes 100, a piezoelectric film 200, a floating electrode 300, and a first filler material 401 and a second filler material 402. The piezoelectric film 200 has a first surface and a second surface; the interdigitated electrodes 100 contact the first surface of the piezoelectric film 200, and the floating electrode 300 contacts the second surface of the piezoelectric film 200, and are distributed throughout the entire layer. The first filler material 401 and the second filler material 402 are alternately distributed. The floating electrodes 300 are arranged corresponding to the interdigitated electrodes 100 to provide a longitudinal electric field. The ratio of the center offset of the second filler material 402 from the interdigitated electrodes 100 to the width W1 of the interdigitated electrodes is preferably ≤20%. The region perpendicular to the interdigitated electrode gap region constitutes a non-longitudinal electric field region; the ratio of the vertical projection center offset of the first filler material 401 from the interdigitated electrode gap region to the width W1 of the interdigitated electrodes is preferably ≤20%. The target mode is the acoustic wave mode excited by the high-frequency acoustic wave resonator under the action of the longitudinal electric field. Optionally, the target mode is one of a high-order Lamb wave, a high-order horizontal shear wave and a high-order Rayleigh mode.

[0138] In another exemplary embodiment, see Figure 22The resonator structure may further include interdigitated electrodes 100, a piezoelectric film 200, a floating electrode 300, and a first filler material 401 and a second filler material 402. The piezoelectric film 200 has a first surface and a second surface; the floating electrode 300 is disposed corresponding to the interdigitated electrodes 100, and the floating electrodes 300 are distributed in an alternating pattern. The first filler material 401 and the floating electrodes 300 are alternately distributed and contact the second surface of the piezoelectric film 200. The second filler material 402 is distributed in a whole layer and is located below the first filler material 401 and the floating electrode 300. In this embodiment, a second filler material corresponding to the floating electrode is disposed on the side of the floating electrode away from the piezoelectric film, and the second filler material is distributed in a whole layer. The materials used for the interdigitated electrodes, piezoelectric material, and floating electrodes are not further described here.

[0139] In another exemplary embodiment, see Figure 23 The resonator structure may further include interdigitated electrodes 100, a piezoelectric film 200, a levitation electrode 300, and a first filler material 401 and a second filler material 402. The levitation electrodes 300 are arranged corresponding to the interdigitated electrodes 100, and are spaced apart. The piezoelectric film 200 has a first surface and a second surface. The levitation electrodes 300 and the second filler material 402 are stacked in layers and alternately distributed with the first filler material 401. The second filler material 402 is located below the levitation electrode 300. In this embodiment, a second filler material corresponding to the levitation electrode is provided on the side of the levitation electrode away from the piezoelectric film. After the second filler material is stacked with the levitation electrode, it is spaced apart from the first filler material. The materials used for the interdigitated electrodes, piezoelectric material, and levitation electrodes are not further described here.

[0140] In some other embodiments, the interdigitated electrodes 100 and the floating electrodes 300 may be made of 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. The piezoelectric material 200 may include one of lithium tantalate, lithium niobate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate, or lead magnesium niobate-lead titanate. Furthermore, the filling material may include one or more of silicon oxide, aluminum oxide, zinc oxide, chromium, nickel, silicon, titanium, copper, aluminum, boron, molybdenum, tungsten, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

[0141] exist Figure 21 、 Figure 22 、 Figure 23In the resonator structure, the interdigitated electrodes and the suspended electrodes form a longitudinal electric field, and the electric field corresponding to the gap between the interdigitated electrodes is a non-longitudinal electric field. The target mode is the acoustic wave mode excited by the high-frequency acoustic wave resonator under the action of the longitudinal electric field. When a parasitic mode exists near the target mode frequency excited by the longitudinal electric field, a filling material is provided to change the velocity and stress distribution of the parasitic mode acoustic wave, thereby affecting the integral of the stress and electric field of the parasitic mode and reducing the electromechanical coupling coefficient. The electromechanical coupling coefficient reflects the cumulative effect of the interaction between stress and electric field within the material volume of the entire piezoelectric film area. When the electromechanical coupling coefficient of the parasitic mode is 0, it is manifested in the disappearance of the parasitic peak in the admittance curve, thereby suppressing the parasitic mode. Therefore, the purpose of suppressing the parasitic mode near the target mode frequency is achieved.

[0142] In some other embodiments, the levitation electrode may also include a structure in which two or more filling materials are sequentially layered on the bottom of the levitation electrode, and the filling material may also include a structure in which two or more filling materials are layered. The corresponding materials of the structures in the embodiments are not further described here.

[0143] The resonator structures described in Embodiments 1 to 3 above may further include a supporting substrate. The supporting substrate includes one of a high-acoustic-velocity supporting layer, a first substrate layer, or a second substrate layer. The first substrate layer structure includes a stacked supporting layer and a high-acoustic-velocity layer. The second substrate layer structure includes a stacked supporting layer and a Bragg reflector layer. The target mode is one of a high-order Lamb wave, a high-order horizontal shear wave, and a high-order Rayleigh mode.

[0144] In another exemplary embodiment, referring to Figure 24 and Figure 25 In order to improve the mechanical stability of the resonator and reduce the propagation loss of sound waves inside the resonator, a high-acoustic-velocity support layer 600 is selected as the supporting substrate of the resonator structure. The product of the resonant frequency of the target mode of the resonator and the center distance λ between the adjacent electrode fingers does not exceed the slow shear wave speed of the high-speed support layer 600. Figure 24 The difference from the first embodiment is that a high acoustic velocity support layer is added to the bottom electrode. Figure 25 and Figure 23 The difference is that the bottom electrode is added with a high acoustic velocity support layer. The high acoustic velocity support layer 600 can be one or more combinations of silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride with different crystal forms and cut shapes.

[0145] In another exemplary embodiment, referring to Figure 26To reduce the production cost of the supporting substrate, the supporting substrate can also be replaced by a first substrate layer 800. The first substrate layer 800 structure includes a stacked supporting layer 802 and a high-acoustic-velocity layer 801. The thickness of the high-acoustic-velocity layer 801 is ≥ 0.5λ, and the material of the high-acoustic-velocity layer 801 can be any of silicon carbide, diamond, diamond-like carbon, aluminum oxide, aluminum nitride, boron nitride, boron carbide, and silicon nitride of varying crystal forms and cuts. The product of the resonant frequency of the target mode of the resonator and the center-to-center spacing λ between adjacent electrode fingers does not exceed the slow shear wave velocity of the high-acoustic-velocity layer 801. In this embodiment, a dielectric layer 700 is further included between the floating electrode 300 and the first substrate layer 800. The dielectric layer 700 can be a single layer or multiple layers, including but not limited to one or more of silicon oxide, silicon nitride, polycrystalline silicon, amorphous silicon, aluminum oxide, and aluminum nitride. The dielectric layer 700 serves as 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. The product of the resonant frequency of the target mode of the resonator and the center spacing λ between adjacent electrode fingers does not exceed the slow shear wave speed of the high sound speed layer 801. In another exemplary embodiment, referring to Figure 27 To improve the operating frequency and quality factor of the resonator and enhance signal clarity, the support substrate can be replaced by the second substrate layer 1000. The second substrate layer 1000 structure includes a stacked support layer 802 and a Bragg reflector layer 900. The Bragg reflector layer 900 has two or more layers. The stacked support layer 802 is made of one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0146] Comparative Example 6

[0147] See Figure 28 An elastic wave device is provided, comprising an interdigitated electrode 100, a piezoelectric film 200, a suspended electrode 300, a dielectric layer 700, and a high acoustic velocity support layer 600 stacked from top to bottom. The interdigitated electrodes 100 serve as the top electrode, and the suspended electrode 300 serves as the bottom electrode. The suspended electrodes 300 are arranged corresponding to the interdigitated electrodes 100, distributed throughout the entire layer, and each suspended electrode 300 has the same potential. The slow shear wave velocity of the high acoustic velocity substrate 600 is greater than the product of the resonant frequency of the target mode and λ.

[0148] Figure 29 Display as Figure 28The corresponding simulated admittance curve. Among them, the high acoustic velocity support layer 600 is silicon carbide, and the dielectric layer 700 is silicon oxide with a thickness of 200nm. The top interdigitated electrode 100 is tungsten with a thickness of 40nm, λ is 1.54μm, and the electrode line width is 385nm. The bottom suspended electrode 300 is tungsten with a thickness of 100nm. The piezoelectric film 200 is lithium niobate, the Euler angle is (0°, 99°, 0°), the thickness is 190nm, and the main mode is SH1 mode. In this embodiment, the high acoustic velocity support layer 600 is silicon carbide, and the dielectric layer 700 is preferably silicon oxide. In some other embodiments, the high acoustic velocity support layer 600 can also be a combination of one or more of diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride with different crystal forms and different cuts. The dielectric layer 700 may also be one or more of silicon nitride, polysilicon, amorphous silicon, aluminum oxide, and aluminum nitride. The dielectric layer 700 may serve as 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.

[0149] from Figure 29 As can be seen from the figure, the LL-SAW acoustic velocity is close to that of the target mode, resulting in a parasitic mode near the resonant frequency of the target mode. In addition, the S1 mode also exists as a parasitic mode at a higher frequency.

[0150] As follows, the technical solutions and effects implemented in this application relative to comparative example 6 are described through examples 4 to 5.

[0151] Example 4

[0152] refer to Figure 30 , a cross-sectional view of an elastic wave resonator is provided, wherein the elastic wave device includes a forked electrode 100, a piezoelectric film 200, a suspended electrode 300, a filling material 400, a dielectric layer 700 and a high acoustic velocity support layer 600 stacked from top to bottom. The slow shear wave velocity of the high acoustic velocity support layer 600 is greater than the product of the resonant frequency of the target mode and λ. The forked electrode 100 serves as the top electrode and the suspended electrode 300 serves as the bottom electrode. The suspended electrode 300 is arranged corresponding to the forked electrode 100, and the suspended electrodes 300 are in an interval distribution morphology, and each of the suspended electrodes 300 is of the same potential. Compared with Comparative Example 6 Figure 28 The difference is that a filler material 400 is added between the floating electrodes, and the filler material 400 is distributed alternately with the floating electrodes 300. The width of the floating electrodes 300 in the direction of the interdigital electrodes does not exceed the length of the aperture region 505, and the length of the aperture region 505 is the length of the aperture region 505 in the direction of the interdigital electrodes.

[0153] Figure 31 Display as Figure 30The simulated admittance curve of the corresponding structure is shown, wherein the high acoustic velocity support layer 600 is silicon carbide, the top interdigitated electrode 100 is tungsten, with a thickness of 40nm, λ of 1.54μm, and an electrode line width W1 of 385nm. The bottom suspended electrode 300 is tungsten, with a thickness of 100nm and a width W2 of 346.5nm, and the filling material 400 is copper. The piezoelectric film is lithium niobate, with Euler angles of (0°, 99°, 0°) and a thickness of 190nm. The main mode is the SH1 mode. In order to achieve temperature compensation, structural stability, and improve the reflection efficiency of the target mode in the thickness direction, this embodiment uses a dielectric layer 700, which is silicon oxide with a thickness of 200nm.

[0154] from Figure 31 As can be seen from the figure, since the filling material 400 is filled with copper, the displacement distribution of the LL-SAW is changed, the LL-SAW mode is completely suppressed, and the S1 mode is also greatly weakened. At the same time, the main mode is basically unaffected. Figure 28 Specifically, the LL-SAW mode acoustic wave propagates at a speed of 3660 m / s in copper and 4608 m / s in tungsten. After copper filling, the LL-SAW propagation speed from the piezoelectric film to the copper changes, resulting in a change in stress T in the non-longitudinal electric field region. Furthermore, the width of the floating electrode 300 in this case is set to 346.5 nm, optimizing the original non-longitudinal electric field distribution. Therefore, under this setting, the stress T and electric field E components are optimized, minimizing the integral of the parasitic mode T and E within the piezoelectric film region, thereby suppressing the parasitic mode LL-SAW.

[0155] Example 5

[0156] refer to Figure 30 A cross-sectional view of an elastic wave resonator is provided. The elastic wave device includes interdigitated electrodes 100, a piezoelectric film 200, a suspended electrode 300, a filling material 400, a dielectric layer 700, and a high-acoustic-velocity support layer 600 stacked from top to bottom. The slow shear wave velocity of the high-acoustic-velocity support layer 600 is greater than the product of the resonant frequency of the target mode and λ. The interdigitated electrodes 100 serve as the top electrode, and the suspended electrode 300 serves as the bottom electrode. The suspended electrodes 300 are arranged corresponding to the interdigitated electrodes 100, are distributed in an intermittent pattern, and each of the suspended electrodes 300 is at the same potential. This embodiment differs from the fourth embodiment in that multiple filling materials are provided in this embodiment. The filling materials 400 are selected from chromium, zinc oxide, nickel, silicon, titanium, copper, aluminum, silicon oxide, and boron. In this case, the line width W2 of the suspended electrode is consistent with the width of the interdigitated electrode W1.

[0157] Figure 32 Corresponding Figure 30 Simulated admittance curves of different filling materials, wherein the high acoustic velocity support layer 600 is silicon carbide, and the dielectric layer 700 is silicon oxide with a thickness of 200nm. The top interdigitated electrode 100 is tungsten with a thickness of 40nm, λ is 1.54μm, and the electrode line width W1 is 385nm. The piezoelectric film 200 is X-cut lithium niobate with a thickness of 190nm. The bottom suspended electrode 300 is tungsten with a thickness of 100nm and a line width W2 of 385nm. The main mode is SH1 mode. The filling material 400 is a different material, and the corresponding mode is SH1 when there is no filling. Figure 22 The resonator structure includes the filling materials other than those in the fourth embodiment. In this case, the line width W2 of the floating electrode is consistent with the width of the interdigital electrode W1.

[0158] from Figure 32 It can be seen that there is a LL-SAW as a parasitic mode on the left side of the resonant frequency. The frequency interval between LL-SAW and the main mode varies with the filling material. At the same time, since the vibration of the main mode is mainly concentrated in the area where the longitudinal electric field passes, that is, below the forked electrode 100, the change of the filling material 400 has almost no effect on the main mode. Therefore, even if the parasitic mode cannot be completely suppressed, the filling material 400 can be selected according to the requirement for the suppression level of a specific out-of-band frequency band, so as to move the parasitic mode to a frequency band that does not require a high out-of-band suppression level. Please refer to Table 1 below for the Young's modulus and sound velocity of the parasitic mode LL-SAW in each filling material.

[0159] Table 1

[0160]

[0161] Specifically, in the same resonator structure, when the sizes of the interdigitated electrodes, piezoelectric film, and suspended electrode materials do not change, the frequency of the parasitic mode in the above-mentioned filling material is highly correlated with the Young's modulus of the material itself and the sound velocity of the parasitic mode in its propagation. When a filling material with a lower Young's modulus than when there is no filling (the electrode material corresponding to the original non-longitudinal field) is selected, the corresponding parasitic mode frequency will decrease, thereby moving away from the target mode, and moving the parasitic mode to a frequency band that does not require a high level of out-of-band suppression. For example, when the filling material is boron, comparing the Young's modulus of boron and tungsten, the Young's modulus of boron is lower than that of tungsten. When boron is filled, the frequency of the parasitic mode LL-SAW decreases, from Figure 32In the figure, it can be seen that LL-SAW is obviously far away from the main mode SH1. In addition, when the Young's modulus of the two filling materials is consistent or not much different, the parasitic mode can be moved outward by selecting a material in which the sound velocity of the parasitic mode is lower. For example, in this application, the Young's modulus data of silicon oxide filling and aluminum filling are comparable. Since silicon oxide is an anisotropic material, the longitudinal wave sound velocity and the shear wave sound velocity are different. The shear sound velocity in silicon oxide is 3198m / s, and the sound velocity in aluminum is 3660m / s. Therefore, after filling silicon oxide, the frequency of the parasitic mode LL-SAW is lower than the frequency after filling aluminum. It is shown in the admittance diagram that the parasitic mode after filling silicon oxide is further away from the main mode SH1.

[0162] Furthermore, a comprehensive review of this embodiment and the fourth embodiment reveals that when the filling material is copper, the parasitic modes of the two embodiments differ significantly. In this embodiment, when the interdigital electrode line width W1 and the floating electrode line width W2 are consistent (W1 = W2 = 385 nm), the use of copper alone can achieve the separation of the parasitic modes, but cannot completely suppress them. In contrast, in the fourth embodiment, when the floating electrode line width W2 is adjusted (W1 = 385 nm, W2 = 346.5 nm), the parasitic mode LL-SAW can be completely suppressed. Therefore, in the fourth embodiment, by setting the filling material to change the frequency of the parasitic mode acoustic wave and affecting the stress distribution in the non-longitudinal electric field, and by adjusting the electrode line width to change the electric field distribution in the non-longitudinal electric field, the presence of the stress T and electric field E components is optimized to minimize the integral of the parasitic mode T and E over the piezoelectric film area, thereby suppressing the parasitic mode LL-SAW.

[0163] In another exemplary embodiment, when the parasitic mode frequency is in a relatively high frequency region near the target mode, a filler material with a relatively high Young's modulus can be selected based on the principles of Example 5. This will increase the corresponding parasitic mode frequency, thereby moving it away from the target mode and shifting the parasitic mode to a frequency band where out-of-band suppression is less critical. Combining Examples 1-5, when the target mode is an acoustic mode excited by a longitudinal electric field, its vibration is primarily concentrated in the region between the top and bottom electrodes, i.e., the region where the longitudinal electric field is distributed. By replacing the suspended electrodes outside the target mode vibration region with a filler material, the parasitic mode's acoustic velocity or displacement distribution is altered while having little impact on the target mode. This can alter the frequency of the parasitic mode or completely suppress it. Unlike filling between interdigitated electrodes, the entire suspended electrode has the same potential. Even if the filler material is conductive, short circuits will not occur and parasitic capacitance will not increase. Furthermore, this technical solution does not form any groove structures in the piezoelectric film, simplifying the process and providing a more stable structure.

[0164] An embodiment of the present application further provides a communication device, comprising the elastic wave resonator described above; the communication device comprises at least one of a filter, a duplexer, and a multiplexer.

[0165] In summary, the present invention has the following beneficial effects: First, based on the principle that when the target mode is an acoustic mode excited by a longitudinal electric field, its vibration is primarily concentrated between the top and bottom electrodes, and adjustments to regions outside the longitudinal electric field have little effect on the main mode, this application selectively adjusts the line width of the suspended electrode in the non-longitudinal electric field region by replacing some of the suspended electrodes with filler materials or placing different filler materials near the suspended electrodes, thereby changing the frequency or displacement distribution of parasitic modes outside the longitudinal electric field, thereby achieving the purpose of removing or completely suppressing the parasitic mode. Second, by setting the potential of the entire suspended electrode to the same, a wider range of filler materials can be selected without causing the generation of additional parasitic capacitance. Furthermore, this technical solution is an optimized solution based on the piezoelectric film structure without changing it, which is more conducive to structural stability and enables large-scale manufacturing of high-performance, high-frequency, wide-bandwidth acoustic wave filters. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0166] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An elastic wave resonator, characterized in that: include: Interdigitated electrodes, piezoelectric films, suspended electrodes, and filling materials; The piezoelectric film has a first surface and a second surface; The interdigitated electrodes are located on the first surface of the piezoelectric film; The suspension electrode is located on the second surface of the piezoelectric film and contacts the piezoelectric film. The suspension electrode and the interdigitated electrodes are correspondingly arranged to form a longitudinal electric field region, and the potential at each position of the suspension electrode is the same. The filling material is located on the second surface of the piezoelectric film and contacts the suspension electrode. The vertical projection of the filling material is at least located in the non-longitudinal electric field region, so that the parasitic mode is suppressed by the filling material or the parasitic mode is kept away from the target mode. The filling material includes a single layer or a composite laminate, at least one layer of which includes a conductive material. The target mode is an acoustic wave mode excited by the elastic wave resonator under the action of a longitudinal electric field.

2. The elastic wave resonator according to claim 1, wherein: The filling material and the suspension electrodes are distributed alternately.

3. The elastic wave resonator according to claim 2, wherein: The filling material corresponding to the suspension electrode is further provided on a side of the suspension electrode away from the piezoelectric film, and the filling material is distributed in an interval manner or in an entire layer.

4. The elastic wave resonator according to claim 1, wherein: The suspension electrodes are distributed in a whole layer, and the filling materials are distributed alternately and are all located below the suspension electrodes.

5. The elastic wave resonator according to claim 1, wherein: The filling material includes one or more combinations of silicon oxide, aluminum oxide, zinc oxide, chromium, nickel, silicon, titanium, copper, aluminum, boron, molybdenum, tungsten, graphene, copper-aluminum alloy, aluminum-silicon alloy, doped silicon, silicon carbide, and gallium nitride.

6. The elastic wave resonator according to claim 1, wherein: The electrical conductivity of the conductive material is ≥50S / m.

7. The elastic wave resonator according to any one of claims 1 to 6, wherein: The interdigitated electrodes are top electrodes, and the corresponding floating electrodes are bottom electrodes; or the interdigitated electrodes are bottom electrodes, and the corresponding floating electrodes are top electrodes.

8. The elastic wave resonator according to claim 7, wherein: A supporting substrate is further provided below the bottom electrode; the supporting substrate comprises one of a high acoustic velocity supporting layer, a first substrate layer or a second substrate layer, wherein the first substrate layer comprises a stacked supporting layer and a high acoustic velocity layer; The second substrate layer includes a stacked support layer and a Bragg reflection layer.

9. The elastic wave resonator according to claim 8, wherein: A dielectric layer is further included between the bottom electrode and the supporting substrate, and the dielectric layer includes a silicon oxide layer, a silicon nitride layer, a polysilicon layer, an amorphous silicon layer, an aluminum oxide layer, and an aluminum nitride layer, or a combination of multiple layers.

10. A communication device, characterized in that: The elastic wave resonator comprises the elastic wave resonator according to any one of claims 1 to 9; the communication device comprises at least one of a filter, a duplexer and a multiplexer.

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