An acoustic wave resonator, filter, and communication device

Abstract

The present application relates to the technical field of microelectronic devices, and particularly relates to an acoustic resonator, a filter and a communication device. The acoustic resonator comprises a support substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged in sequence from bottom to top; the piezoelectric layer comprises a plurality of first piezoelectric regions and a plurality of second piezoelectric regions arranged alternately along a first direction; Euler angles of the first piezoelectric regions are not equal to Euler angles of the second piezoelectric regions; the first direction is a length direction of the support substrate; a distance between centers of adjacent first piezoelectric regions in the plurality of first piezoelectric regions is equal to a distance between centers of adjacent second piezoelectric regions in the plurality of second piezoelectric regions; a product of the distance between the centers of the adjacent first piezoelectric regions and a frequency of a target mode of the acoustic resonator is less than a sound velocity of the support substrate; the target mode is an acoustic wave mode excited under action of a longitudinal electric field. The wavelength of the target mode is reduced without reducing the electrode line width, higher frequency is realized, ohmic loss is reduced and power capacity is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microelectronic devices, and in particular to an acoustic wave resonator, a filter and a communication device. Background Art

[0002] Modern wireless communication systems have increasingly stringent requirements for signal quality. Low loss, wide bandwidth, tunability, and temperature stability have become universal goals in the communications industry. The target mode operating frequency of a bulk acoustic wave (BAW) resonator is inversely proportional to the thickness of the piezoelectric film. Reducing the thickness of the piezoelectric film can increase the operating frequency. However, for suspended film BAW resonators, excessively thin piezoelectric films pose mechanical stability issues. To avoid this drawback, solid-state assembly BAW resonators can be used. However, the processing of the Bragg reflector layer in solid-state assembly BAW resonators is very difficult, and the Bragg reflector layer can introduce new parasitic effects. Existing surface acoustic wave (SAW) resonators based on piezoelectric heterogeneous substrates offer significant advantages in terms of Q value, volume, temperature stability, and power handling. The sound velocity of currently commonly used SAW modes is limited by the sound velocity of the supporting substrate, and therefore the operating frequency is limited by the linewidth of the interdigital electrodes. As the operating frequency increases, the decrease in electrode width leads to an increase in ohmic loss and a decrease in power handling. Furthermore, regardless of whether a BAW or SAW structure is used, the presence of multiple non-zero piezoelectric coefficients in the piezoelectric material will lead to the generation of parasitic modes, which in turn reduces the filter's out-of-band rejection. Therefore, increasing the operating frequency of the target mode and avoiding various types of parasitic modes without reducing the electrode linewidth are key to achieving high-performance, high-frequency, and wide-bandwidth filters. Summary of the Invention

[0003] To solve the above technical problems, the present application discloses, in one aspect, an acoustic wave resonator, which includes a supporting substrate, a bottom electrode, a piezoelectric layer, and a top electrode arranged in sequence from bottom to top;

[0004] The piezoelectric layer includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions alternately arranged along a first direction; the Euler angles of the first piezoelectric regions are not equal to the Euler angles of the second piezoelectric regions; the first direction is the length direction of the supporting substrate;

[0005] The distance between the centers of adjacent first piezoelectric regions among the multiple first piezoelectric regions is equal to the distance between the centers of adjacent second piezoelectric regions among the multiple second piezoelectric regions; the product of the distance between the centers of adjacent first piezoelectric regions and the frequency of the target mode of the acoustic wave resonator is less than the sound velocity of the supporting substrate; the target mode is an acoustic wave mode excited under the action of a longitudinal electric field.

[0006] In some optional embodiments, the piezoelectric coefficient corresponding to the target mode in the first piezoelectric region and the piezoelectric coefficient corresponding to the target mode in the second piezoelectric region are opposite in number.

[0007] In some optional embodiments, the piezoelectric layer includes a plurality of sub-piezoelectric layers arranged in sequence along the second direction, each sub-piezoelectric layer includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions arranged alternately along the first direction; the piezoelectric coefficients corresponding to adjacent piezoelectric regions along the second direction in the plurality of sub-piezoelectric layers of the target mode are opposite; and the second direction is the height direction of the supporting substrate.

[0008] In some optional embodiments, the piezoelectric layer includes a plurality of sub-piezoelectric layers arranged in sequence along a third direction, each sub-piezoelectric layer includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions arranged alternately along a first direction; the third direction is the width direction of the supporting substrate; the piezoelectric coefficients of the target mode corresponding to adjacent piezoelectric regions along the third direction in the plurality of sub-piezoelectric layers are the same.

[0009] In some optional embodiments, one or more of a metal layer, a dielectric layer and a bonding layer are provided between the multiple piezoelectric sub-layers.

[0010] In some optional embodiments, the piezoelectric layer includes a plurality of first sub-piezoelectric layers and a plurality of second sub-piezoelectric layers staggered along the second direction;

[0011] The Euler angle of the first piezoelectric region in the first sub-piezoelectric layer is not equal to the Euler angle of the first piezoelectric region in the second sub-piezoelectric layer, and / or the Euler angle of the second piezoelectric region in the first sub-piezoelectric layer is not equal to the Euler angle of the second piezoelectric region in the second sub-piezoelectric layer.

[0012] In some optional embodiments, the bottom electrode is one of a surface electrode, a suspended electrode, and a special-shaped electrode;

[0013] The top electrode is one of a surface electrode, an interdigitated electrode, a suspended electrode and a special-shaped electrode.

[0014] In some optional embodiments, the top electrode and the bottom electrode cover at least one group of adjacent first piezoelectric regions and second piezoelectric regions.

[0015] In some optional embodiments, the target mode is one of a longitudinal leakage surface acoustic wave, a horizontal shear wave, a Rayleigh mode, and higher-order modes thereof.

[0016] In some optional embodiments, a dielectric layer is provided between the supporting substrate and the bottom electrode.

[0017] In some optional embodiments, the acoustic wave resonator has at least one parasitic mode, and a piezoelectric coefficient corresponding to the at least one parasitic mode in the first piezoelectric region is the same as a piezoelectric coefficient corresponding to the at least one parasitic mode in the second piezoelectric region.

[0018] In another aspect, the present application discloses a filter comprising the above-mentioned acoustic wave resonator.

[0019] In another aspect, the present application discloses a communication device comprising the above-mentioned acoustic wave resonator;

[0020] The communication device includes at least one of a filter, a duplexer, and a multiplexer.

[0021] By adopting the above technical solution, the acoustic wave resonator provided by this application has the following beneficial effects:

[0022] The acoustic wave resonator includes a supporting substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged in sequence from bottom to top; the piezoelectric layer includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions arranged alternately along a first direction; the Euler angle of the first piezoelectric region is not equal to the Euler angle of the second piezoelectric region; the first direction is the length direction of the supporting substrate; the distance between the centers of adjacent first piezoelectric regions in the plurality of first piezoelectric regions is equal to the distance between the centers of adjacent second piezoelectric regions in the plurality of second piezoelectric regions; the product of the distance between the centers of adjacent first piezoelectric regions and the frequency of the target mode of the acoustic wave resonator is less than the sound velocity of the supporting substrate; the target mode is an acoustic wave mode excited under the action of a longitudinal electric field. Compared with the single-layer structure of the piezoelectric layer of the prior art resonator, the structure provided by the present application in which the piezoelectric layer is arranged in a periodic arrangement can reduce the wavelength of the target mode without reducing the electrode line width, achieve a higher frequency, reduce ohmic loss and improve power capacity; and by rotating the appropriate Euler angle, parasitic modes can also be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 is a cross-sectional view of a first acoustic wave resonator provided in an embodiment of the present application;

[0025] Figure 2 This is a schematic structural diagram of a comparative example 1 provided in the embodiments of the present application;

[0026] Figure 3 This is a structural diagram of a comparative example 2 provided in the embodiments of the present application;

[0027] Figure 4 This is a simulation result diagram including comparative example 1 and comparative example 2 provided in an embodiment of the present application;

[0028] Figure 5 This embodiment of the present application provides Figure 4 The vibration mode diagram corresponding to comparative example 1;

[0029] Figure 6 This embodiment of the present application provides Figure 4 The vibration mode diagram corresponding to comparative example 2;

[0030] Figure 7 This is a simulation result diagram including structure 1 and structure 2 provided in an embodiment of the present application;

[0031] Figure 8 This embodiment of the present application provides Figure 7 The vibration mode diagram corresponding to the parasitic mode in structure 1;

[0032] Figure 9 This embodiment of the present application provides Figure 7 The vibration mode diagrams corresponding to the target modes in structures 1 and 2;

[0033] Figure 10 This is a structural diagram of Comparative Example 3 provided in the embodiments of the present application;

[0034] Figure 11 This is a simulation result diagram including Comparative Example 3 and Structure 2 provided in an embodiment of the present application;

[0035] Figure 12 This embodiment of the present application provides Figure 11 The vibration mode diagram corresponding to the target mode in Comparative Example 3;

[0036] Figure 13 This embodiment of the present application provides Figure 11 The vibration mode diagram corresponding to the parasitic mode in Comparative Example 3;

[0037] Figure 14 This is a simulation result diagram corresponding to the second acoustic wave resonator provided in the embodiment of the present application;

[0038] Figure 15 is a cross-sectional view of a third acoustic wave resonator provided in an embodiment of the present application;

[0039] Figure 16 This embodiment of the present application provides Figure 15 Admittance curve corresponding to the structure shown;

[0040] Figure 17 is a cross-sectional view of a fourth acoustic wave resonator provided in an embodiment of the present application;

[0041] Figure 18 This embodiment of the present application provides Figure 17 Admittance curve corresponding to the structure shown;

[0042] Figure 19 This embodiment of the present application provides Figure 17 The vibration mode diagram corresponding to the structure shown;

[0043] Figure 20 is a cross-sectional view of a fourth acoustic wave resonator provided in an embodiment of the present application;

[0044] Figure 21 is a cross-sectional view of a fifth acoustic wave resonator provided in an embodiment of the present application;

[0045] Figure 22 is a cross-sectional view of a sixth acoustic wave resonator provided in an embodiment of the present application;

[0046] Figure 23 is a cross-sectional view of a seventh acoustic wave resonator provided in an embodiment of the present application;

[0047] Figure 24 is a top view of an eighth acoustic wave resonator provided in an embodiment of the present application;

[0048] Figure 25 is a top view of a ninth acoustic wave resonator provided in an embodiment of the present application;

[0049] Figure 26 is a top view of a tenth acoustic wave resonator provided in an embodiment of the present application;

[0050] Figure 27 is a top view of an eleventh acoustic wave resonator provided in an embodiment of the present application;

[0051] Figure 28 This is a top view of the twelfth acoustic wave resonator provided in an embodiment of the present application.

[0052] The following is a supplementary description of the accompanying drawings:

[0053] 1-support substrate; 2-bottom electrode; 3-piezoelectric layer; 301-first piezoelectric region; 302-second piezoelectric region; 303-sub-piezoelectric layer; 304-first sub-piezoelectric layer; 305-second sub-piezoelectric layer; 4-top electrode; 5-middle layer. DETAILED DESCRIPTION

[0054] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0055] References to "one embodiment" or "embodiment" herein refer to specific features, structures, or characteristics that may be included in at least one implementation of the present application. Throughout the description of this application, it should be understood that the terms "upper," "lower," "top," and "bottom," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplification. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature designated "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, the terms "first," "second," etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential sequence. It should be understood that such terms are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0056] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein. For example, a specified range from "1 to 10" should be considered to include any and all subranges between a minimum of 1 and a maximum of 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0057] One of the existing solutions is a bulk acoustic wave mode excited by the longitudinal electric field of the target mode, which adopts the form of a suspended bottom electrode and a top interdigitated electrode, and the resonant frequency is determined by the thickness of the piezoelectric film. Since the leakage of acoustic wave energy is avoided by suspending the film, the line width of the metal electrode is not restricted. However, as the frequency increases, the piezoelectric film gradually becomes thinner, and its mechanical stability faces challenges. Another existing solution is to use a high-speed acoustic support substrate to constrain it. The target mode is a high-speed longitudinal leakage surface acoustic wave (LL-SAW) mode, but the upper limit of its operating frequency is determined by the speed of sound of the supporting substrate and the period of the interdigitated electrode, that is, the cut-off frequency. As the frequency increases, the width of the interdigitated electrode gradually becomes narrower, which not only puts more stringent requirements on the lithography accuracy, but also increases the ohmic loss and reduces the power capacity. Moreover, the interdigitated electrode structure will cause the horizontal and vertical electric fields to exist at the same time, and thus will also excite related parasitic modes.

[0058] To this end, this proposal utilizes the acoustic wave mode excited by the longitudinal electric field as the target mode, and employs periodically arranged piezoelectric regions to define the wavelength of the target mode in the horizontal direction. The operating frequency of the target mode is increased by reducing the period of the piezoelectric film rather than the electrode width. This structure increases the resonant frequency without exceeding the cutoff frequency of the supporting substrate, thus keeping the target mode well confined to the substrate surface. The structure is simple, stable, and has good heat dissipation. Furthermore, by not reducing the electrode width, low ohmic losses and high power handling are ensured. Furthermore, this structure offers design flexibility, and by selecting appropriate Euler angles of adjacent piezoelectric films, various types of parasitic modes can be further suppressed.

[0059] See also Figure 1 , which shows a cross-sectional view of the first acoustic wave resonator provided by an embodiment of the present application, wherein the acoustic wave resonator includes a supporting substrate 1, a bottom electrode 2, a piezoelectric layer 3 and a top electrode 4 arranged in sequence from bottom to top; the piezoelectric layer 3 includes a plurality of first piezoelectric regions 301 and a plurality of second piezoelectric regions 302 arranged alternately along a first direction; the Euler angle of the first piezoelectric region 301 is not equal to the Euler angle of the second piezoelectric region 302; the first direction is the length direction of the supporting substrate 1; the distance between the centers of adjacent first piezoelectric regions 301 in the plurality of first piezoelectric regions 301 is equal to the distance between the centers of adjacent second piezoelectric regions 302 in the plurality of second piezoelectric regions 302; the product of the distance between the centers of adjacent first piezoelectric regions 301 and the frequency of the target mode of the acoustic wave resonator is less than the sound velocity of the supporting substrate 1; the target mode is an acoustic wave mode excited under the action of a longitudinal electric field. Therefore, this scheme uses the acoustic wave mode excited by the longitudinal electric field as the target mode and adopts periodically arranged piezoelectric regions to define the wavelength of the target mode in the horizontal direction. The operating frequency of the target mode is increased by reducing the period of the piezoelectric region instead of the electrode width. Therefore, the wavelength of the target mode can be reduced without reducing the electrode line width, achieving a higher frequency, reducing ohmic loss and increasing power capacity; by rotating the appropriate Euler angle, parasitic modes can also be suppressed.

[0060] In the embodiment of the present disclosure, the first direction may be as follows: Figure 1 The x direction shown, the second direction hereinafter may refer to Figure 1 The z direction in the third direction can refer to Figure 1 y direction in .

[0061] In some optional embodiments, the piezoelectric coefficient corresponding to the target mode in the first piezoelectric region 301 and the piezoelectric coefficient corresponding to the target mode in the second piezoelectric region 302 are opposite in number.

[0062] In some optional embodiments, the target mode is one of a longitudinal leakage surface acoustic wave, a horizontal shear wave, a Rayleigh mode, and higher-order modes thereof.

[0063] In some optional embodiments, a dielectric layer is provided between the support substrate 1 and the bottom electrode 2. Optionally, the dielectric layer is a single layer structure or a composite structure, including a bonding layer, a temperature compensation layer, a low acoustic velocity layer, a high acoustic velocity layer, etc. Optionally, the support substrate 1 is a material that is easily formed and processed; the material of the support substrate 1 includes any one of quartz, silicon, sapphire, spinel, and yttrium aluminum garnet; the material of the high acoustic velocity layer includes 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 cuts.

[0064] Optionally, the support substrate 1 is a combination of one or more of silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, boron nitride, boron carbide and silicon nitride with different crystal forms and different cut shapes.

[0065] Optionally, the material of the piezoelectric layer 3 is a combination of one or more of lithium tantalate, lithium niobate, potassium niobate, lead zirconate titanate, or lead magnesium niobate-lead titanate;

[0066] Optionally, the material of the top electrode 4 includes a combination of one or more of copper, aluminum, gold, silver, tungsten, platinum, nickel, chromium, molybdenum, titanium, graphene, copper-aluminum alloy, and aluminum-silicon alloy; the material of the bottom electrode 2 includes 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.

[0067] See also Figure 2 and 3 , which show the structural schematic diagrams of Comparative Example 1 and Comparative Example 2 respectively. Figure 2 Compared with the structure shown in the figure, the difference is that the piezoelectric layer 3 of comparative example 1 is a single-layer structure; the difference between comparative example 2 and comparative example 1 is that the top electrode 4 of comparative example 2 is an interdigitated electrode, and the top electrode 4 of comparative example 1 is a surface electrode; specifically, in the structures of the above comparative examples 1 and 2, the material of the supporting substrate 1 is 4H-SiC, the bottom electrode 2 is 80nm tungsten, the Euler angle of the piezoelectric layer 3 is lithium niobate (0°, 99°, 0°), and the thickness is 200nm; the top electrode 4 is 80nm aluminum, wherein the period of the interdigitated electrodes is 1.2μm (that is, the distance between the centers of adjacent electrode fingers is 1.2μm). By performing simulation tests on the structures of the above comparative examples 1 and 2, it can be obtained as follows Figure 4From the simulation results shown, it can be seen that the TSM bulk acoustic wave excited by the surface electrode structure of comparative example 1 leaks into the supporting substrate 1, so the admittance ratio of the resonator is very low. After adopting the interdigital electrode, the TSM is converted into the SH1 mode, and the product of its operating frequency and the period of the interdigital electrode is less than the sound velocity of the supporting substrate 1. Therefore, the acoustic wave energy is well confined to the surface of the supporting substrate 1. However, the interdigital electrodes cause the simultaneous existence of transverse and longitudinal electric fields, and the piezoelectric coefficient components in the piezoelectric film that are unrelated to the main mode lead to the existence of a large number of parasitic modes (such as SHO, Rayleigh, and LL-SAW). Further by comparison Figure 5 and Figure 6 It can be seen that the bulk acoustic waves of the TSM in Comparative Example 1 almost completely leak into the supporting substrate 1. This indicates that, regardless of whether the top electrode 4 is a surface electrode or an interdigitated electrode, as long as its piezoelectric layer 3 is a single-layer structure, there will be problems of acoustic waves leaking into the substrate or generating parasitic modes.

[0068] Further, based on Figure 1 The structure shown in the figure is structure 1 and structure 2, and the target mode is SH1 mode, and the piezoelectric coefficient corresponding to the target mode is e34. Among them, the first piezoelectric region 301 in structure 1 and structure 2 is lithium niobate with Euler angles of (0°, 99°, 0°), and the piezoelectric coefficient is e34 of -3.89C / m 2 The Euler angles of the second piezoelectric region 302 in structure 1 are (0°, 279°, 0°), and the Euler angles of the second piezoelectric region 302 in structure 2 are (180°, 99°, 0°). The piezoelectric coefficient e34 corresponding to the second piezoelectric region 302 is 3.89 C / m 2 , that is, the sign of the piezoelectric coefficient is opposite to that of the first piezoelectric region 301. The period P of the piezoelectric layer 3 (the period is the distance between the center of the adjacent first piezoelectric region 301 and the center of the second piezoelectric region 302) is 1.2μm, and the widths of the first piezoelectric region 301 and the second piezoelectric region 302 are both 0.6μm. The other parameters are the same as those of the comparative example 1. Through the simulation test of the above structure 1 and structure 2, the following can be obtained: Figure 7 From the simulation results shown, it can be seen that although the surface electrode structure is adopted, the piezoelectric layer 3 has periodicity, thereby converting the TSM bulk acoustic wave into the SH1 mode and being confined to the surface of the supporting substrate 1. Figure 3 Compared with the structure shown in FIG1 , due to the use of surface electrodes, the SH0 and Rayleigh modes mainly excited by the transverse electric field are greatly weakened or completely suppressed. However, for structure 1, the LL-SAW excited by the longitudinal electric field still exists as a parasitic mode. This is because the piezoelectric coefficient related to the LL-SAW is mainly e31, and the piezoelectric coefficient e31 in the first piezoelectric region 301 is -2.54C / m 2 The piezoelectric coefficient e31 of the second piezoelectric region 302 of structure 1 is 2.54 C / m 2Therefore, the LL-SAW is also confined to the substrate surface. The piezoelectric coefficient e31 of the second piezoelectric region 302 of structure 2 is -2.54 C / m 2 This means that in the second structure, for the LL-SAW mode, the first piezoelectric region 301 and the second piezoelectric region 302 are completely equivalent, and the wavelength of the LL-SAW is no longer determined by the period P of the piezoelectric layer 3 but by the line width of the electrode. Therefore, the LL-SAW mode at this time has a relatively large wavelength, and its operating frequency drops significantly or leaks into the supporting substrate 1 due to the very small thickness-to-wavelength ratio. Further comparison Figure 8 and Figure 9 It can be seen that without the use of interdigital electrodes, both modes are confined to the substrate surface. This shows that by selecting appropriate Euler angles of the first piezoelectric region 301 and the second piezoelectric region 302, it is possible to confine the target mode while suppressing parasitic modes.

[0069] See also Figure 10 , which shows a schematic diagram of the structure of a comparative example 3 provided by the embodiment of the present application. Compared with the structure corresponding to structure 2, comparative example 3 does not have a supporting substrate 1. By performing simulation tests on comparative example 3 and structure 2, it can be obtained as follows Figure 11 As shown in the simulation results, it can be seen that since the piezoelectric coefficient corresponding to the TEM bulk acoustic wave mode is e33, the e33 of the first piezoelectric region 301 is 1.28C / m 2 , the e33 of the second piezoelectric region 302 is also 1.28C / m 2 . Therefore, for the TEM bulk acoustic wave mode, the first piezoelectric region 301 and the second piezoelectric region 302 are completely equivalent. The structure of comparative example 3 can transform TSM into SH1 mode, but TEM is not transformed into S1 mode and is still a bulk acoustic wave mode. When there is no supporting substrate 1, TEM becomes a parasitic mode at a higher frequency. When there is a supporting substrate 1, the mode leaks into the supporting substrate 1. Therefore, in addition to stabilizing the structure, the supporting substrate 1 can also be used to filter the parasitic mode. Further, by comparison Figure 12 and Figure 13 It can be seen that when there is no supporting substrate 1 (ie, comparative example 3), the periodic SH1 mode and the non-periodic TEM bulk acoustic wave are excited simultaneously.

[0070] Please continue reading Figure 1Specifically, the supporting substrate 1 is made of 4H-SiC, the bottom electrode 2 is made of 20nm aluminum, the piezoelectric layer 3 is made of lithium niobate with a thickness of 80nm, and the top electrode 4 is made of 20nm aluminum. The target mode is LL-SAW, and the corresponding piezoelectric coefficients are e31 and e33. The Euler angles of the first piezoelectric region 301 and the second piezoelectric region 302 are (0°, 54°, 0°) and (180°, 234°, 0°), respectively, and e31 is -1.94C / m2 and 1.94C / m 2 , while e33 is 4.53C / m 2 and -4.53C / m 2 Therefore, the wavelength of the LL-SAW is equal to the period P of the piezoelectric layer 3 and is 200 nm, and the width of the first piezoelectric region 301 and the second piezoelectric region 302 is 100 nm. Figure 14 and Figure 11 It can be seen that when the period P of the piezoelectric layer 3 is small enough, the operating frequency of the target mode can be increased to tens of GHz, while the line width of the electrode itself is not reduced.

[0071] See also Figure 15 , which shows a cross-sectional view of the third acoustic wave resonator provided by the embodiment of the present application. Figure 1 Compared with the structure shown, Figure 15 An intermediate layer 5 is provided between the support substrate 1 and the bottom electrode 2 of the structure shown. Specifically, the material of the support substrate 1 is diamond, the intermediate layer 5 can be a dielectric layer, and is 40nm silicon oxide, the bottom electrode 2 is 20nm aluminum, the material of the piezoelectric layer 3 is lithium niobate, and the thickness is 180nm, the top electrode 4 is 20nm aluminum, the period P of the piezoelectric layer 3 is 1μm, and the width of the first piezoelectric region 301 and the second piezoelectric region 302 is 500nm. The Euler angles and target modes of the first piezoelectric region 301 and the second piezoelectric region 302 are the same as those of structure 2. Figure 16 It can be seen that when a diamond substrate with a high acoustic velocity is used, the target mode resonance frequency can reach above 10 GHz when the period P of the piezoelectric layer 3 is 1 μm.

[0072] In some optional embodiments, see Figure 17The piezoelectric layer 3 includes a plurality of sub-piezoelectric layers 303 arranged in sequence along the second direction. Each sub-piezoelectric layer 303 includes a plurality of first piezoelectric regions 301 and a plurality of second piezoelectric regions 302 arranged alternately along the first direction. The piezoelectric coefficients corresponding to adjacent piezoelectric regions along the second direction in the plurality of sub-piezoelectric layers 303 in the target mode are opposite. The second direction is the height direction of the supporting substrate 1. Optionally, the Euler angles of adjacent piezoelectric regions along the second direction may be unequal. Specifically, the supporting substrate 1 is made of diamond, the bottom electrode 2 is made of 20nm tungsten, the piezoelectric layer 3 is made of lithium niobate, the thickness of the sub-piezoelectric layer 303 is 85nm, the top electrode 4 is made of 20nm aluminum, the period P of the piezoelectric layer 3 is 0.5μm, and the widths of the first piezoelectric region 301 and the second piezoelectric region 302 are 250nm. The Euler angles of the first piezoelectric region 301 and the second piezoelectric region 302 are the same as those of the structure 2, the target mode is the SH2 mode (i.e., the second-order horizontal shear mode), and the corresponding piezoelectric coefficient is e34. Figure 18 It can be seen that the resonant frequency of the target mode reaches about 20 GHz, and the total thickness of the piezoelectric layer 3 is 170 nm. Figure 16 Therefore, by increasing the number of sub-piezoelectric layers 303 of the piezoelectric layer 3 in the third direction, the resonant frequency of the resonator can be increased at the same total thickness. Figure 19 It can be seen that Figure 17 The structure shown can excite higher-order acoustic modes and increase the resonance frequency at the same total thickness by selecting appropriate Euler angles of different sub-piezoelectric layers 303 .

[0073] In some alternative embodiments, see Figure 20 , compared to Figure 15 , also includes a high-velocity layer. Optional, see Figure 21 The piezoelectric layer 3 includes a plurality of first sub-piezoelectric layers 304 and a plurality of second sub-piezoelectric layers 305 arranged in an staggered manner along the second direction; the Euler angle of the first piezoelectric region 301 in the first sub-piezoelectric layer 304 is not equal to the Euler angle of the first piezoelectric region 301 in the second sub-piezoelectric layer 305, and the Euler angle of the second piezoelectric region 302 in the first sub-piezoelectric layer 304 is not equal to the Euler angle of the second piezoelectric region 302 in the second sub-piezoelectric layer 305, that is, the first sub-piezoelectric layer 304 includes two piezoelectric regions with different Euler angles, and the second sub-piezoelectric layer 305 includes two piezoelectric regions with different Euler angles. Alternatively, the Euler angles of the first piezoelectric region 301 in the first piezoelectric sub-layer 304 may be equal to the Euler angles of the second piezoelectric region 302 in the second piezoelectric sub-layer 305, the Euler angles of the second piezoelectric region 302 in the first piezoelectric sub-layer 304 may be equal to the Euler angles of the first piezoelectric region 301 in the second piezoelectric sub-layer 305, and the Euler angles of the first piezoelectric region 301 and the second piezoelectric region 302 in the same piezoelectric sub-layer may be unequal. Alternatively, the Euler angles of all four piezoelectric regions may be unequal.

[0074] In some other optional embodiments, an intermediate layer 5 is provided between the plurality of sub-piezoelectric layers 303, and the intermediate layer 5 may be one or more of a metal layer, a dielectric layer and a bonding layer. Figure 22 The metal layer is provided between the sub-piezoelectric layers 303, which may be as shown in FIG. Figure 23 As shown, a dielectric layer is provided between the sub-piezoelectric layers 303 .

[0075] In some other optional embodiments, the bottom electrode 2 is one of a surface electrode, a suspended electrode, and a special-shaped electrode; the top electrode 4 is one of a surface electrode, an interdigitated electrode, a suspended electrode, and a special-shaped electrode. Optionally, the top electrode 4 and the bottom electrode 2 cover at least one set of adjacent first piezoelectric regions 301 and second piezoelectric regions 302. Figure 24 , the top electrode 4 and the bottom electrode 2 can be both surface electrodes, and the overlapping area is rectangular. Figure 25 , the bottom electrode 2 may be a suspended electrode, the top electrode 4 may be composed of two electrodes, each electrode covers a plurality of periods of piezoelectric layers 3, and a period of piezoelectric layer 3 may include a group of adjacent first piezoelectric regions 301 and second piezoelectric regions 302. Optional, please refer to Figure 26 , the bottom electrode 2 may be a suspended electrode, the top electrode 4 may be composed of interdigitated electrodes, and each electrode finger in the interdigitated electrodes covers multiple periods of the piezoelectric layer 3. In addition, the top electrode and the bottom electrode may each be composed of at least two electrodes, and each electrode covers at least one period of the piezoelectric film. Optional, please refer to Figure 27 The top electrode 4 and the bottom electrode 2 may also be of a special-shaped structure, so that the overlapping area with the piezoelectric layer 3 is a polygon.

[0076] In some alternative embodiments, see Figure 28The piezoelectric layer 3 includes a plurality of sub-piezoelectric layers 303 arranged in sequence along a third direction (i.e., the y direction), and each sub-piezoelectric layer 303 includes a plurality of first piezoelectric regions 301 and a plurality of second piezoelectric regions 302 arranged alternately along the first direction; the third direction is the width direction of the supporting substrate 1; the piezoelectric coefficients corresponding to adjacent piezoelectric regions along the third direction in the plurality of sub-piezoelectric layers 303 of the target mode are the same. Optionally, the Euler angles of the multiple sub-piezoelectric layers 303 along the third direction may be the same or different. For example, the piezoelectric layer 3 may include multiple first sub-piezoelectric layers 304 and multiple second sub-piezoelectric layers 305 staggered along the third direction, and the first sub-piezoelectric layer 304 and the second sub-piezoelectric layer 305 both include multiple first piezoelectric regions 301 and multiple second piezoelectric regions 302 alternately arranged in the first direction. The Euler angles of the first piezoelectric region 301 in the first sub-piezoelectric layer 304 and the second sub-piezoelectric layer 305 may be different, or the Euler angles of the second piezoelectric region 302 in the first sub-piezoelectric layer 304 and the second sub-piezoelectric layer 305 may be different, or the Euler angles of the first piezoelectric region 301 and the second piezoelectric region 302 in the first sub-piezoelectric layer 304 and the second sub-piezoelectric layer 305 are not equal. Optionally, the types of the sub-piezoelectric layers 303 staggered along the third direction may not be limited to Figure 28 The two types shown (ie, the first sub-piezoelectric layer 304 and the second sub-piezoelectric layer 305 ) may also include three or four types.

[0077] In the embodiment of the present disclosure, when there is at least one parasitic mode in the acoustic wave resonator, the at least one parasitic mode satisfies at least one of the following conditions: the corresponding piezoelectric coefficient in the first piezoelectric region 301 is the same as the corresponding piezoelectric coefficient in the second piezoelectric region 302; when there are multiple piezoelectric regions in both the first direction and the second direction, the signs in adjacent piezoelectric regions in the second direction are the same; when there are multiple piezoelectric regions in both the first direction and the third direction, the signs in adjacent piezoelectric regions in the first direction and the third direction are the same or opposite.

[0078] An acoustic wave resonator provided by an embodiment of the present application, through a periodically arranged piezoelectric layer 3, selects appropriate Euler angles of adjacent piezoelectric regions in the propagation direction so that the piezoelectric coefficients of the target mode in the adjacent piezoelectric regions have opposite signs. At this time, the wavelength of the target mode in the horizontal direction is determined by the period of the piezoelectric film, rather than the period of the interdigitated electrode. Specifically, in the first direction, by selecting appropriate Euler angles of adjacent piezoelectric regions, the piezoelectric coefficients of the parasitic mode in the adjacent piezoelectric regions have the same sign. This effectively increases the wavelength of the parasitic mode in the horizontal direction, so that the parasitic mode has an extremely small resonant frequency, or leaks to the supporting substrate 1 due to a very small ratio of thickness to wavelength. If a multilayer piezoelectric region is further used in the second direction, so that the piezoelectric coefficients of the target mode in the adjacent piezoelectric regions in the thickness direction have opposite signs, the frequency of the target mode can also be increased under the same total piezoelectric film thickness. In addition, by reducing the period P of the piezoelectric film, the cutoff frequency of the supporting substrate 1 and the operating frequency of the target mode can be increased. At the same time, the line width of the electrode is not reduced, ensuring lower ohmic loss and higher power capacity.

[0079] In another aspect, the present application discloses a filter comprising the above-mentioned acoustic wave resonator.

[0080] On the other hand, the present application discloses a communication device, which includes the above-mentioned acoustic wave resonator; the communication device includes at least one of a filter, a duplexer, and a multiplexer.

[0081] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An acoustic wave resonator, characterized in that It includes a supporting substrate, a bottom electrode, a piezoelectric layer and a top electrode arranged in sequence from bottom to top, wherein the supporting substrate is a high acoustic velocity supporting substrate; The piezoelectric layer includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions alternately arranged along a first direction; the Euler angles of the first piezoelectric regions and the Euler angles of the second piezoelectric regions are not equal; the first direction is the length direction of the supporting substrate, and the top electrode and the bottom electrode cover at least one group of adjacent first piezoelectric regions and second piezoelectric regions; The distance between the centers of adjacent first piezoelectric regions among the plurality of first piezoelectric regions is equal to the distance between the centers of adjacent second piezoelectric regions among the plurality of second piezoelectric regions; the product of the distance between the centers of adjacent first piezoelectric regions and the frequency of a target mode of the acoustic wave resonator is less than the speed of sound of the supporting substrate; the piezoelectric coefficient corresponding to the target mode in the first piezoelectric region is an inverse number of the piezoelectric coefficient corresponding to the target mode in the second piezoelectric region; and the target mode is an acoustic wave mode excited under the action of a longitudinal electric field; The piezoelectric layer includes a plurality of sub-piezoelectric layers arranged in sequence along a third direction, each of the sub-piezoelectric layers includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions arranged alternately along the first direction; the third direction is the width direction of the supporting substrate; the piezoelectric coefficients of the target mode corresponding to adjacent piezoelectric regions along the third direction in the plurality of sub-piezoelectric layers are the same.

2. The acoustic wave resonator according to claim 1, characterized in that The piezoelectric layer includes a plurality of sub-piezoelectric layers arranged in sequence along the second direction, each of the sub-piezoelectric layers includes a plurality of first piezoelectric regions and a plurality of second piezoelectric regions arranged alternately along the first direction; the piezoelectric coefficients of the target mode corresponding to adjacent piezoelectric regions along the second direction in the plurality of sub-piezoelectric layers are opposite numbers; the second direction is the height direction of the supporting substrate.

3. The acoustic wave resonator according to claim 2, characterized in that One or more of a metal layer, a dielectric layer and a bonding layer are provided between the plurality of sub-piezoelectric layers.

4. The acoustic wave resonator according to claim 2, characterized in that The piezoelectric layer includes a plurality of first sub-piezoelectric layers and a plurality of second sub-piezoelectric layers staggered along the second direction; The Euler angle of the first piezoelectric region in the first sub-piezoelectric layer is not equal to the Euler angle of the first piezoelectric region in the second sub-piezoelectric layer, and / or the Euler angle of the second piezoelectric region in the first sub-piezoelectric layer is not equal to the Euler angle of the second piezoelectric region in the second sub-piezoelectric layer.

5. The acoustic wave resonator according to any one of claims 1 to 4, characterized in that: The bottom electrode is one of a surface electrode, a suspended electrode and a special-shaped electrode; The top electrode is one of a surface electrode, an interdigitated electrode, a suspended electrode and a special-shaped electrode.

6. The acoustic wave resonator according to claim 1, characterized in that The target mode is one of longitudinal leakage surface acoustic waves, horizontal shear waves, Rayleigh modes, and higher-order modes thereof.

7. The acoustic wave resonator according to claim 1, characterized in that A dielectric layer is provided between the supporting substrate and the bottom electrode.

8. The acoustic wave resonator according to claim 1, wherein The acoustic wave resonator has at least one parasitic mode, and a piezoelectric coefficient corresponding to the at least one parasitic mode in the first piezoelectric region is the same as a piezoelectric coefficient corresponding to the at least one parasitic mode in the second piezoelectric region.

9. A filter, characterized in that: The device comprises the acoustic wave resonator according to any one of claims 1 to 8.

10. A communication device, characterized in that: comprising the acoustic wave resonator according to any one of claims 1 to 8; The communication device includes at least one of a filter, a duplexer, and a multiplexer.

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