Elastic wave resonator and communication device thereof

Abstract

The invention provides an elastic wave resonator and a communication device thereof, the elastic wave resonator comprises an interdigital electrode, a piezoelectric film, a suspension electrode and a filling material, the filling material is adopted to replace part of the suspension electrode, or different filling materials are arranged near the suspension electrode, and the line width of the suspension electrode is selectively set; the method is used for changing the frequency or displacement distribution of a parasitic mode with vibration distribution in an area outside a longitudinal electric field, so that the aim of removing the parasitic mode or completely inhibiting the parasitic mode is fulfilled. The scheme is an optimization scheme on the basis of not changing the structure of the piezoelectric film, is more beneficial to structure stability and can be used for manufacturing the high-frequency large-bandwidth acoustic wave filter with high performance on a large scale.

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] The RF front-end module is an important component of mobile terminal communication. The bandpass filter is the core device responsible for signal transmission and reception, which only allows signals of specific frequencies to pass through. In order to meet the requirements of communication systems and protocols for signal-to-noise ratio, high requirements are placed on the passband flatness, in-band insertion loss, band edge steepness, rectangularity, and out-of-band suppression of filter components, and these requirements are increasing day by day. Elastic wave filters play a vital role in the field of RF front-end devices with their advantages such as small size and simple process.

[0003] Elastic wave filter technology is the most widely used RF filter technology at present, mainly including Bulk Acoustic Wave (BAW), Surface Acoustic Wave (SAW) filter technology, and 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 with discontinuous acoustic impedance 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 that do not require high 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, the parasitic modes excited by the transverse electric field are suppressed. The target mode of this scheme is the thickness shear mode, which is excited by the longitudinal electric field, and the vibration is 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, and the parasitic modes excited by the transverse electric field can be suppressed, but it also makes the structure of the resonator more fragile.

[0005] In another prior art 2, reference is made to Figure 2, by completely embedding the interdigital electrodes 21, the higher harmonics in the horizontal propagation direction are suppressed. This scheme utilizes the higher-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 are completely embedded in the piezoelectric film LiNbO3 22. However, the disadvantage of this scheme 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, under the premise of 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 a frequency band where the out-of-band suppression requirements are not high, so as to 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 technical personnel in this field.

[0007] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, 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 arranged correspondingly 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, and the vertical projection of the filling material is at least located in the non-longitudinal electric field region, so that the parasitic mode can be suppressed by the filling material or the parasitic mode can be kept 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 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 arranged 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 suspension electrodes are distributed in layers, and the filling materials are all located below the suspension 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 ≥ 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 also located below the area where the suspension electrode and the filling material are alternately distributed and is distributed in a whole layer.

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

[0024] The first substrate layer includes a stacked support layer and a high sound 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 a communication device thereof. On the one hand, 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, the present application adopts a filling material to replace part of the suspended electrode in the non-longitudinal electric field area, or sets different filling materials near the suspended electrode, and selectively sets the line width of the suspended electrode to change the frequency or displacement distribution of the parasitic mode outside the longitudinal electric field, so as to achieve the purpose of removing the parasitic mode or completely suppressing the parasitic mode. On the other hand, by optimizing and setting the electric potential of the entire suspended electrode to be the same, a wider range of filling materials can be selected, and other parasitic capacitances will not be generated. At the same time, the technical solution is an optimization solution based on not changing the structure of the piezoelectric film, which is more conducive to structural stability and large-scale manufacturing of high-performance, high-frequency, and large-bandwidth acoustic wave filters. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 It is 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 Simulated admittance curve corresponding to the structure shown.

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

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

[0037] Fig. 9It is a schematic diagram of the structure of the elastic wave device in comparative example 4.

[0038] Fig.10 Display as Fig. 9 Simulated admittance curve corresponding to the structure shown.

[0039] Fig.11 It is a schematic diagram of the structure of the elastic wave device in comparative example five.

[0040] Fig.12 Display as Fig.11 Simulated admittance curve corresponding to the structure shown.

[0041] Fig.13 It shows a schematic diagram of the structure of the elastic wave device in the first embodiment and the second embodiment.

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

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

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

[0045] Fig.17 Display as Fig.13 Schematic diagram of the resonator structure in which the top electrode is a suspended electrode and the bottom electrode is an interdigitated electrode.

[0046] Fig.18 Display as Fig.17 Simulated admittance curve corresponding to the structure shown.

[0047] Fig.19 Display as Fig.13 Based on this, a schematic diagram of the elastic wave device structure with a composite stack of filling materials and suspended electrodes alternately distributed.

[0048] Fig. 20 Display as Fig.19 Simulated admittance curve corresponding to the structure shown.

[0049] Fig.21 The schematic diagram of the elastic wave device structure shows that the filling materials are all located below the suspension electrodes and are distributed alternately.

[0050] Fig. 22 A schematic diagram of the elastic wave device structure is shown in which filling materials and suspended electrodes are alternately distributed, and another filling material is located under the suspended electrode.

[0051] Fig.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] Fig.24 Display as Fig.13 Schematic diagram of the elastic wave device structure with a high acoustic velocity support layer added to the structural basis.

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

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

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

[0056] Fig.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] Fig.29 Display as Fig.28 Simulated admittance curve corresponding to the structure shown.

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

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

[0060] Fig.32 Display as Fig.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 interdigitated 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 gap

[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, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways 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 in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0092] For ease of description, spatial relational terms such as “under”, “below”, “below”, “below”, “over”, etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other 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, and may also include 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 may 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 illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout 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 also Figure 3, an elastic wave device is provided, the elastic wave device comprises an interdigitated electrode 100, a piezoelectric film 200 and a suspended electrode 300 stacked from top to bottom, wherein the interdigitated electrode 100 is used as a top electrode and the suspended electrode 300 is used as a bottom electrode. The interdigitated electrode 100 comprises a first interdigitated electrode and a second interdigitated electrode, the extension direction of which is perpendicular to the propagation direction of the sound wave, and the center spacing between adjacent electrode fingers of the first interdigitated electrode and the center spacing between adjacent electrode fingers of the second interdigitated electrode are both λ.

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

[0102] from Figure 4 It can be seen that the piezoelectric coefficient components in the piezoelectric film 200 that are unrelated to the main mode lead to the existence of parasitic modes, wherein near the anti-resonance frequency of the main mode and at a higher frequency than the main mode, there are higher harmonics of the 0th order mode such as LL-SAW in the horizontal direction. These parasitic modes will cause the passband fluctuation of the filter or the reduction of the out-of-band suppression level.

[0103] Comparative Example 2

[0104] See also Figure 5 , a cross-sectional view of a comparative elastic wave resonator is provided, comprising an interdigitated electrode 100, a piezoelectric film 200, and a suspended electrode 300. The interdigitated electrode 100 has a line width of W1, and the difference from the comparative example 1 is that the suspended electrode 300 is replaced by a discrete finger strip, and the potential of all the suspended electrodes 300 is the same, and the width of the discrete finger strip of the suspended electrode 300 is W2.

[0105] Figure 6 Display as Figure 5 The simulated admittance curve corresponding to the structure shown in the figure, wherein the interdigitated electrode 100 at the top is aluminum, with a thickness of 50nm, λ is 2.9μm, and W1 is 1015nm. The floating electrode 300 at the bottom is aluminum, with a thickness of 50nm, and the width W2 of the floating electrode 300 is 870nm. The piezoelectric film 200 is Y171-cut lithium niobate, with a thickness of 300nm. The main mode is A1 mode. Therefore, from 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 also 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 the comparative example 2 is that the floating electrode 300 is replaced by the lower interdigital electrode 102, the potentials of the adjacent upper interdigital electrodes 101 are opposite, the potentials of the adjacent lower interdigital electrodes 102 are opposite, and the potentials of the electrodes on both sides of the piezoelectric film 200 at the same position are opposite. The line width of the upper interdigital electrode is W1, and the line width of the lower interdigital electrode is W2.

[0108] Figure 8 Display as Figure 7 The simulated admittance curve corresponding to the structure shown in the figure, where 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 the figure 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 also Fig. 9 , a cross-sectional view of a comparative elastic wave resonator is provided, including a top interdigital electrode 100, a piezoelectric film 200 and a suspension electrode 300, and a filling material 400 between the top interdigital electrodes 100. The interdigital electrodes 100 are top electrodes, and the suspension electrodes 300 are bottom electrodes. The difference from comparative example 1 is that the filling material 400 is filled between the interdigital electrodes 100, and the line width of the interdigital electrodes 100 is W1.

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

[0112] Comparative Example 5

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

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

[0115] from Fig.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] It can be seen from the implementation results of comparative examples 1 to 5 that when the corresponding materials, dimensions, etc. of the resonator structure do not change, the overall suppression effect of the parasitic mode LL-SAW near the anti-resonance frequency by changing the floating electrodes to discrete fingers, changing the floating electrodes to interdigitated electrodes, and setting the interdigitated electrode filling material is not significant. The following is an explanation of the technical solutions and technical effects of the present application relative to comparative examples 1 to 5 through embodiments 1 to 3.

[0117] Embodiment 1

[0118] See also Fig.13 , a cross-sectional view of an elastic wave resonator is provided, including an interdigitated electrode 100, a piezoelectric film 200, a bottom suspension electrode 300 and a filling material 400. The morphology of the interdigitated electrode 100 can be found in the following related Fig.14As described above, in this embodiment, the suspension electrode 300 is arranged corresponding to the interdigital electrode 100, the suspension electrodes 300 are distributed in an interval morphology, and each of the suspension electrodes 300 is of equal potential. The filling material 400 is located between the suspension electrodes 300 and is distributed alternately with the suspension electrodes 300 and is distributed in layers. The interdigital electrodes 100 are top electrodes, and the suspension electrodes 300 are bottom electrodes. The line width of the interdigital electrodes 100 is W1, and the width of the suspension electrode is W2. The suspension electrodes 300 are arranged corresponding to the interdigital electrodes 100 to provide a longitudinal electric field, and their center positions coincide. The vertical projection center positions of the gap regions of the filling material 400 and the interdigital electrodes 100 coincide. In other embodiments, the center positions of the floating electrode 300 and the interdigital electrode 100 may also be offset, and both can provide a longitudinal electric field, wherein the ratio of the center offset between the floating electrode 300 and the interdigital electrode 100 to the width W1 of the interdigital electrode is preferably ≤20%. Similarly, the ratio of the vertical projection center position offset between the filling material 400 and the interdigital electrode gap region to the width W1 of the interdigital electrode is preferably ≤20%.

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

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

[0121] from Fig.15 It can be seen that although the parasitic mode near the positive resonance frequency still exists, the parasitic mode near the anti-resonance frequency is weakened. In this embodiment, in order to compare and illustrate that the filling material 400 uses insulating aluminum oxide to suppress the parasitic mode near the anti-resonance frequency, the material dimensions corresponding to the interdigital electrodes, the suspension electrodes, and the piezoelectric film of the resonator are not changed compared with the comparative example 1.

[0122] This solution does not form a groove structure in the piezoelectric film. Compared with the prior art 1, the stability of the structure is ensured. At the same time, in the target mode excited by the longitudinal electric field, the vibration is concentrated between the top electrode and the bottom electrode. This embodiment does not use an embedded electrode structure, and other properties of the resonator are not affected. In addition, due to the equipotential setting of the suspended electrode, parasitic capacitance will not be increased in the longitudinal electric field region to reduce 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 setting of the interdigital electrode line width W1 and the suspension electrode line width W2, when the integral of the stress and electric field product of the parasitic mode in the piezoelectric film region is 0, the parasitic mode corresponding to the longitudinal electric field target mode is suppressed. In Example 1, since the potentials of the bottom suspension electrode and the insulating aluminum oxide are different, the non-longitudinal electric field has a significant change relative to the electric field in Comparative Example 1 after the insulating aluminum oxide is filled at the bottom, and the simple filling of insulating aluminum oxide cannot completely suppress the parasitic mode. By setting the filling material insulating aluminum oxide and optimizing the interdigital electrode line width W1 and the suspension electrode line width W2, not only the parasitic mode near the anti-resonance frequency can be significantly suppressed, but also the parasitic mode near the positive resonant frequency can be 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 the electric field, and the electromechanical coupling coefficient reflects the cumulative effect of the interaction between stress and electric field in 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, so the parasitic mode is suppressed. In the embodiment, the filling material is set to change the frequency of the parasitic mode sound wave and affect 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, so as to optimize the existence of 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 Denote the piezoelectric strain constant, the compliance constant under constant electric field, and the dielectric constant under constant stress, respectively. dv represents the volume element. The technique used in the embodiment optimizes the presence of the stress T and the electric field E component in the non-longitudinal electric field region to minimize the parasitic mode T and E integral in the piezoelectric film region. Therefore, the interaction energy in the piezoelectric film is reduced to nearly 0, thereby suppressing the parasitic mode.

[0127] Embodiment 2

[0128] Based on the structure of the first embodiment, the resonator structure is as follows: Fig.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 distributed at intervals, and each of the suspension electrodes 300 is of equal potential.

[0129] Fig.16 The simulated admittance curve corresponding to the second embodiment is shown, wherein the interdigitated electrode 100 is aluminum, the line width W1 is 1015nm, the thickness is 50nm, and λ is 2.9μm. The suspended electrode 300 is aluminum, the thickness is 50nm, and the electrode width W2 is 870nm. The potential of each position of the suspended electrode is the same. The piezoelectric film 200 is Y171-cut lithium niobate, and the thickness is 300nm. 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, and the main mode is the A1 mode. Preferably, the conductivity of the conductive aluminum oxide is ≥50S / m.

[0130] from Fig.16It can be seen that the parasitic modes in a wide frequency range are basically suppressed without sacrificing the frequency and electromechanical coupling coefficient of the main mode. Since the vibration of the main mode A1 is mainly concentrated between the top electrode and the bottom electrode, replacing a part of the suspended electrode in the area where the vibration of the main mode A1 is weak, that is, the non-longitudinal electric field area, has almost no effect on the main mode. The replaced conductive aluminum oxide has the same potential as the bottom suspended electrode, and does not change the distribution of the non-longitudinal electric field before replacement. Instead, it changes the stress distribution in the non-longitudinal electric field and reduces the electromechanical coupling coefficient, thereby achieving the purpose of suppressing the parasitic mode.

[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 may also be the top electrodes and the interdigital electrodes may be the bottom electrodes. Fig.17 The resonator structure is as follows: the levitation electrode 300 is a top electrode. The interdigital electrode 100 is a bottom electrode. The levitation electrode 300 is arranged corresponding to the interdigital electrode 100, and each of the levitation electrodes 300 is of equal potential. The filling material 400 is conductive aluminum oxide and is distributed in layers alternately with the levitation electrodes 300.

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

[0133] Embodiment 3

[0134] In order to overcome the difficult process of preparing the conductive aluminum oxide, the resonator can also be made of Fig.19 The resonator structure shown, Fig.19 The structure includes an interdigital electrode 100, a piezoelectric film 200, a suspension electrode 300, a first filling material 401 and a second filling material 402. The suspension electrode 300 is arranged corresponding to the interdigital electrode 100, the suspension electrodes 300 are distributed in an interval shape, and each of the suspension electrodes 300 is equipotential. The first filling material and the second filling material are distributed in layers. In addition, the first filling material 401 and the second filling material 402 are laminated and alternately distributed with the suspension electrodes 300. The interdigital electrode 100 is a top electrode, and the suspension electrode 300 is a bottom electrode.

[0135] Fig. 20 Display as Fig.19The simulated admittance curve corresponding to the structure, wherein the interdigital electrode 100 is aluminum, the line width W1 is 1015nm, the thickness is 50nm, and λ is 2.9μm. The suspended electrode 300 is aluminum, the thickness is 50nm, and the electrode width W2 is 870nm. The potential of each position of the suspended electrode 300 is the same. The piezoelectric film 200 is Y171-cut lithium niobate, and the thickness is 300nm. The first filling material 401 is aluminum, the second filling material 402 is insulating aluminum oxide, the thickness of the first filling material 401 is 1nm, and the main mode is A1 mode.

[0136] from Fig. 20 It can be seen that the parasitic mode LL-SAW is suppressed, which is the same as the result in Example 2. In order to provide the same potential as the floating electrode 300, a thinner 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 Fig.21 The resonator structure may also include an interdigitated electrode 100, a piezoelectric film 200, a suspended electrode 300, and a first filling material 401 and a second filling material 402. The piezoelectric film 200 has a first surface and a second surface; the interdigitated electrode 100 contacts the first surface of the piezoelectric film 200, and the suspended electrode 300 contacts the second surface of the piezoelectric film 200, and is distributed in a whole layer. The first filling material 401 and the second filling material 402 are distributed alternately. The suspended electrode 300 is arranged corresponding to the interdigitated electrode 100 to provide a longitudinal electric field, and the ratio of the center offset of the second filling material 402 and the interdigitated electrode 100 to the width W1 of the interdigitated electrode is preferably ≤20%. The area in the vertical direction of the interdigitated electrode gap area constitutes a non-longitudinal electric field area; the ratio of the vertical projection center position offset of the first filling material 401 and the interdigitated electrode gap area to the width W1 of the interdigitated electrode 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 Fig. 22The resonator structure may further include an interdigitated electrode 100, a piezoelectric film 200, a suspended electrode 300, a first filling material 401, and a second filling material 402. The piezoelectric film 200 has a first surface and a second surface; the suspended electrode 300 is arranged corresponding to the interdigitated electrode 100, and the suspended electrode 300 is in an interval distribution morphology; the first filling material 401 and the suspended electrode 300 are alternately distributed and contact the second surface of the piezoelectric film 200; the second filling material 402 is distributed in a whole layer and is located below the first filling material 401 and the suspended electrode 300. In this embodiment, a second filling material corresponding to the suspended electrode is arranged on the side of the suspended electrode away from the piezoelectric film, and the second filling material is distributed in a whole layer. The materials used for the interdigitated electrodes, piezoelectric materials, and suspended electrodes are not described in detail here.

[0139] In another exemplary embodiment, see Fig.23 , the resonator structure may further include an interdigitated electrode 100, a piezoelectric film 200, a suspension electrode 300, a first filling material 401 and a second filling material 402. The suspension electrode 300 is arranged corresponding to the interdigitated electrode 100, and the suspension electrode 300 is in an alternate distribution morphology. The piezoelectric film 200 has a first surface and a second surface; the suspension electrode 300 and the second filling material 402 are stacked in layers and alternately distributed with the first filling material 401. The second filling material 402 is located below the suspension electrode 300. In this embodiment, a second filling material corresponding to the suspension electrode is arranged on the side of the suspension electrode away from the piezoelectric film, and the second filling material is stacked with the suspension electrode and alternately distributed with the first filling material. The materials used for the interdigitated electrodes, piezoelectric materials, and suspension electrodes are not described in detail here.

[0140] In some other embodiments, the interdigitated electrodes 100 and the suspended electrodes 300 may 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. The piezoelectric material 200 includes 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 includes 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 Fig.21 , Fig. 22 , Fig.23In the resonator structure, the interdigitated electrodes and the suspended electrodes form a longitudinal electric field, and the electric field corresponding to the interdigitated electrode gap 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 suspension electrode may also include a structure in which two or more filling materials are sequentially stacked in layers at the bottom of the suspension electrode, and the filling material may also include a structure in which two or more filling materials are stacked in layers. The corresponding materials of the structure in the embodiment are not described in detail here.

[0143] The resonator structure described in the above embodiments 1 to 3 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 reflection 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 Fig.24 and Fig.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 support substrate of the resonator structure, and the product of the resonant frequency of the target mode of the resonator and the center spacing λ of the adjacent electrode fingers does not exceed the slow shear wave acoustic velocity of the high-speed support layer 600. Fig.24 The difference from the first embodiment is that a high acoustic velocity support layer is added to the bottom electrode. Fig.25 and Fig.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 a combination of one or more of silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride of different crystal forms and different cuts.

[0145] In another exemplary embodiment, referring to Fig.26In order to reduce the production cost of the support substrate, the support substrate can also be replaced by the first substrate layer 800. The structure of the first substrate layer 800 includes a stacked support 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 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 product of the resonant frequency of the target mode of the resonator and the center spacing λ of the adjacent electrode fingers does not exceed the slow shear wave sound velocity of the high acoustic velocity layer 801. In this embodiment, a dielectric layer 700 is also included between the floating electrode 300 and the first substrate layer 800. The dielectric layer 700 can be a single layer material or a multilayer material, 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 the adjacent electrode fingers does not exceed the slow shear wave speed of the high sound speed layer 801. In another exemplary embodiment, referring to Fig. 27 In order to improve the operating frequency and quality factor of the resonator and enhance the clarity of the signal, the support substrate can also be replaced by the second substrate layer 1000. The second substrate layer 1000 structure includes a stacked support layer 802 and a Bragg reflection layer 900; the number of layers of the Bragg reflection layer 900 is more than 2, and the material of the stacked support layer 802 includes one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet.

[0146] Comparative Example 6

[0147] See also Fig.28 , an elastic wave device is provided, the elastic wave device comprises an interdigital electrode 100, a piezoelectric film 200, a suspension electrode 300, a dielectric layer 700 and a high acoustic velocity support layer 600 stacked from top to bottom. The interdigital electrode 100 is used as a top electrode and the suspension electrode 300 is used as a bottom electrode. The suspension electrode 300 is arranged corresponding to the interdigital electrode 100, the suspension electrode 300 is distributed in the whole layer, and each of the suspension electrodes 300 is equipotential. 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] Fig.29 Display as Fig.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 interdigitated electrode 100 at the top is tungsten with a thickness of 40nm, λ is 1.54μm, and the electrode line width is 385nm. The floating electrode 300 at the bottom 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 the 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 be used 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 Fig.29 It can be seen that the sound velocity of LL-SAW is close to the target mode, which causes a parasitic mode near the resonant frequency of the target mode. In addition, there is also an S1 mode as a parasitic mode at a higher frequency.

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

[0151] Embodiment 4

[0152] refer to Fig.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. Among them, 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 Fig.28 The difference is that a filling material 400 is added in the middle of the suspension electrode, and the filling material 400 is distributed alternately with the suspension electrode 300. The width of the suspension electrode 300 in the extension direction of the interdigital electrodes does not exceed the length of the aperture area 505, and the length of the aperture area 505 is the length of the aperture area 505 in the extension direction of the interdigital electrodes.

[0153] Fig.31 Display as Fig.30The simulated admittance curve of the corresponding structure, wherein the high acoustic velocity support layer 600 is silicon carbide, the top interdigital electrode 100 is tungsten, with a thickness of 40nm, λ is 1.54μm, and the electrode line width W1 is 385nm. The bottom suspended electrode 300 is tungsten, with a thickness of 100nm, a width W2 of 346.5nm, and the filling material 400 is copper. The piezoelectric film is lithium niobate, the Euler angle is (0°, 99°, 0°), and the thickness is 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 adopts a dielectric layer 700, and the dielectric layer 700 is silicon oxide with a thickness of 200nm.

[0154] from Fig.31 It can be seen that since the filling material 400 is filled with copper, the displacement distribution of 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. Fig.28 Specifically, the propagation speed of the LL-SAW mode sound wave in the copper material is 3660m / s, and the propagation speed in the tungsten material is 4608m / s. After the copper material is filled, the propagation speed of the LL-SAW from the piezoelectric film to the copper material changes, so the stress T in the non-longitudinal electric field area changes. At the same time, the width of the floating electrode 300 in this case is set to 346.5nm, which optimizes the electric field distribution of the original non-longitudinal electric field. Therefore, under this setting, the stress T and the electric field E component are optimized, minimizing the integral of the parasitic mode T and E in the piezoelectric film area, so that the parasitic mode LL-SAW is suppressed.

[0155] Embodiment 5

[0156] refer to Fig.30 , a cross-sectional view of an elastic wave resonator is provided, wherein the elastic wave device comprises 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. Among them, the forked electrode 100 is used as a top electrode and the suspended electrode 300 is used as a bottom electrode. The suspended electrode 300 is arranged corresponding to the forked electrode 100, and the suspended electrode 300 is in an interval distribution morphology, and each of the suspended electrodes 300 is equipotential. The difference from the fourth embodiment is that this embodiment provides a variety of filling materials, and the filling material 400 is respectively filled with chromium, zinc oxide, nickel, silicon, titanium, copper, aluminum, silicon oxide, and boron materials. The line width W2 of the suspended electrode in this case is consistent with the width of the forked electrode W1.

[0157] Fig.32 Corresponding Fig.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 floating electrode 300 is tungsten with a thickness of 100nm and a line width W2 of 385nm. The main mode is the SH1 mode. The filling material 400 is a different material, and the corresponding Fig. 22 The resonator structure includes the filling materials other than those in the fourth embodiment, and the line width W2 of the suspension electrode in this case is consistent with the width of the interdigital electrode W1.

[0158] from Fig.32 It can be seen that there is 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 demand 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. The Young's modulus and sound velocity of the parasitic mode LL-SAW in each filling material refer to Table 1 below.

[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 speed of sound at which the parasitic mode propagates. When a filling material with a lower Young's modulus than when there is no filling (the original electrode material corresponding to the non-longitudinal field) is selected, the corresponding parasitic mode frequency will be reduced, 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 is reduced, from Fig.32It 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 the present application, the Young's modulus data of silicon oxide filling and aluminum filling are equivalent. 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 that 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] Further, it can be seen from the present embodiment and the fourth embodiment that when the filling material is copper, there is a significant difference in the parasitic modes of the two embodiments. In the present embodiment, when the line width W1 of the interdigital electrode and the line width W2 of the suspension electrode are consistent (W1=W2=385nm), the use of copper material alone can achieve the distance of the parasitic mode, but cannot completely suppress the parasitic mode. In the fourth embodiment, when the width of the suspension electrode line width W2 is adjusted (W1=385nm, W2=346.5nm), the parasitic mode LL-SAW can be completely suppressed. Therefore, in the fourth embodiment, the filling material is set to change the frequency of the parasitic mode sound wave and affect the stress distribution in the non-longitudinal electric field, and the electric field distribution in the non-longitudinal electric field is changed by adjusting the electrode line width, thereby optimizing the existence of the stress T and the electric field E component, so as to minimize the integral of the parasitic mode T and E on the piezoelectric film area, so that the parasitic mode LL-SAW is suppressed.

[0163] In another exemplary embodiment, when the parasitic mode frequency is in a region with a higher frequency near the target mode, according to the principle of embodiment five, a filling material with a relatively high Young's modulus can be selected, and the corresponding parasitic mode frequency will increase, 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. Comprehensive embodiments one to five, when the target mode is an acoustic wave mode excited by a longitudinal electric field, its vibration is mainly concentrated in the region between the top electrode and the bottom electrode, that is, the region where the longitudinal electric field is distributed. By replacing the suspended electrode outside the target mode vibration region with a filling material, the target mode is almost not affected while the sound velocity or displacement distribution of the parasitic mode is changed, so the frequency of the parasitic mode can be changed or the parasitic mode can be completely suppressed. Unlike filling between the interdigitated electrodes, the electric potential of the entire suspended electrode is the same, and even if the filling material is a conductive material, there will be no short circuit problem, and the parasitic capacitance will not be increased. In addition, this technical solution does not form any groove structure in the piezoelectric film, the process is simple, and the structure is more stable.

[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: on the one hand, 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, the present application replaces part of the suspended electrode with a filling material in the non-longitudinal electric field area, or sets different filling materials near the suspended electrode, and can selectively set the line width of the suspended electrode 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 setting the electric potential of the entire suspended electrode to be the same, a wider range of filling materials can be selected, and other parasitic capacitances will not be generated. At the same time, the technical solution is an optimization solution based on the piezoelectric film structure without changing it, which is more conducive to structural stability and can manufacture high-performance, high-frequency, and large-bandwidth acoustic wave filters on a large scale. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still 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 is in contact with the piezoelectric film. The suspension electrode and the interdigitated electrodes are arranged correspondingly to form a longitudinal electric field region, and the potential of each position of the suspension electrode is the same. The filling material is located on the second surface of the piezoelectric film and is in contact with the suspension electrode, and the vertical projection of the filling material is at least located in the non-longitudinal electric field region, so as to suppress the parasitic mode or keep the parasitic mode away from the target mode through the filling material; The target mode is the acoustic wave mode excited by the high-frequency acoustic wave resonator under the action of the longitudinal electric field.

2. The elastic wave resonator according to claim 1, characterized in that: The filling material and the suspension electrodes are distributed alternately, and the filling material includes a single layer or a composite laminate.

3. The elastic wave resonator according to claim 2, characterized in that: The filling material corresponding to the suspension electrode is further arranged 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.

4. The elastic wave resonator according to claim 1, characterized in that: The suspension electrodes are distributed in a whole layer, and the filling materials are distributed alternately and are all located below the suspension electrodes; the filling materials include a single layer or a composite laminate.

5. The elastic wave resonator according to claim 1, characterized in that: 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, characterized in that: The filling material comprises a conductive material, and the conductivity is ≥50S / m.

7. The elastic wave resonator according to any one of claims 1 to 6, characterized in that: 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, characterized in that: A supporting substrate is also included below the bottom electrode; the supporting substrate includes one of a high acoustic velocity supporting layer, a first substrate layer or a second substrate layer, wherein the first substrate layer includes 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, characterized in that: A dielectric layer is also 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.

10. A communication device, characterized in that: It comprises the elastic wave resonator as claimed in 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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