Resonator, filter and electronic device

Abstract

The embodiments of the present application relate to the technical field of resonators. Disclosed are a resonator, a filter and an electronic device. The resonator is, for example, a YBAR, and comprises a first electrode, a plurality of piezoelectric layers and a plurality of second electrodes, wherein the plurality of piezoelectric layers are stacked on the first electrode; the plurality of second electrodes are located on the side of the plurality of piezoelectric layers away from the first electrode, and are spaced apart on the side of the plurality of piezoelectric layers away from the first electrode; and the plurality of piezoelectric layers comprise a first piezoelectric layer and a second piezoelectric layer adjacent to each other, piezoelectric tensor components of spurious modes of piezoelectric materials of the first piezoelectric layer and the second piezoelectric layer differing in terms of magnitude. In this way, the spurious modes corresponding to the first piezoelectric layer and the second piezoelectric layer can cancel each other out, such that the spurious modes can be effectively suppressed or even eliminated, thereby optimizing the performance of the resonator.

Description

Resonators, filters and electronic equipment

[0001] This application claims priority to Chinese patent application filed on November 14, 2024, with application number 202411625669.X and entitled "Resonator, Filter and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of resonator technology, and more particularly to a resonator, a filter having a resonator, and an electronic device including a filter or a resonator. Background Technology

[0003] With the development of communication technology, the demand for resonators in electronic devices will increase significantly. Among them, bulk acoustic resonators such as horizontally-excited bulk acoustic resonators (XBAR), vertically-excited bulk acoustic resonators (YBAR), and film bulk acoustic resonators (FBAR) have attracted widespread attention. For example, XBAR and YBAR have high electromechanical coupling coefficients and quality factors, which can meet the passband bandwidth requirements of the Sub-6GHz frequency band.

[0004] Among them, YBAR can improve the relatively larger electromechanical coupling coefficient and more efficient resonant modes, and can be applied in a larger passband bandwidth.

[0005] However, in current YBARs, several different types of parasitic modes (or parasitic clutter modes) have appeared near the resonance frequency (fr) and anti-resonance frequency (fa) ranges. These parasitic clutter modes significantly interfere with the main resonant mode, causing many problems for the resonator and filter performance. For example, these parasitic clutter modes can increase the passband ripple of the filter and worsen its out-of-band rejection performance. Summary of the Invention

[0006] This application provides a resonator, a filter having a resonator, and an electronic device including a filter or a resonator for suppressing parasitic modes.

[0007] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0008] In a first aspect, a resonator is provided, which can be a bulk acoustic wave resonator, such as a YBAR. The resonator includes: a first electrode, a plurality of piezoelectric layers, and a plurality of second electrodes. The plurality of piezoelectric layers are stacked on the first electrode. Alternatively, the plurality of piezoelectric layers can be understood as being stacked along the thickness direction of the first electrode. The plurality of second electrodes are located on the side of the plurality of piezoelectric layers away from the first electrode and are spaced apart on this side. Alternatively, the plurality of second electrodes can be understood as being spaced apart and laid flat on the side of the plurality of piezoelectric layers away from the first electrode.

[0009] Among them, the above-mentioned multiple piezoelectric layers include adjacent first piezoelectric layers and second piezoelectric layers, and the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer and the second piezoelectric layer are different in magnitude.

[0010] The resonator provided in some embodiments of this application stacks multiple piezoelectric layers along the thickness direction of the first electrode between a first electrode and multiple second electrodes. The parasitic mode piezoelectric tensor components of adjacent first and second piezoelectric layers have opposite signs; that is, the polarities of the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first and second piezoelectric layers are opposite. This allows the parasitic miscellaneous modes corresponding to the first and second piezoelectric layers to couple and cancel each other out, effectively suppressing or even eliminating parasitic miscellaneous modes and optimizing the resonator's performance. When this resonator is applied to a filter, it can reduce the filter's passband ripple and enhance out-of-band rejection performance.

[0011] In the possible design approaches of the first aspect, the parasitic modal piezoelectric tensor components include at least one or more of the following: e 11 e 16 e 31 and e 35 For example, in parasitic mode piezoelectric tensor components including e 11 and e 35 In the case of the parasitic mode piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 11 parasitic mode piezoelectric tensor components e of the piezoelectric material of the second piezoelectric layer 11 The parasitic mode piezoelectric tensor components e of the piezoelectric material of the first piezoelectric layer are different in size. 35 parasitic mode piezoelectric tensor components e of the piezoelectric material of the second piezoelectric layer 35 The magnitudes differ. For example, in the parasitic mode piezoelectric tensor components, e... 16 and e 35 In the case of the parasitic mode piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 16 parasitic mode piezoelectric tensor components e of the piezoelectric material of the second piezoelectric layer 16Different sizes, and / or, the parasitic mode piezoelectric tensor components e of the piezoelectric material of the first piezoelectric layer 35 parasitic mode piezoelectric tensor components e of the piezoelectric material of the second piezoelectric layer 35 The magnitudes differ. For example, in the parasitic mode piezoelectric tensor components, e... 31 In the case of the parasitic mode piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 31 parasitic mode piezoelectric tensor components e of the piezoelectric material of the second piezoelectric layer 31 The magnitudes differ. For example, in the parasitic mode piezoelectric tensor components, e... 35 In the case of the parasitic mode piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 parasitic mode piezoelectric tensor components e of the piezoelectric material of the second piezoelectric layer 35 They are different sizes.

[0012] In one possible design approach, the parasitic mode piezoelectric tensor components of the piezoelectric materials in the first and second piezoelectric layers have opposite signs. That is, the polarities of the parasitic mode piezoelectric tensor components of the piezoelectric materials in the first and second piezoelectric layers are opposite. This allows the parasitic miscellaneous modes corresponding to the first and second piezoelectric layers to couple and cancel each other out, effectively suppressing or even eliminating parasitic miscellaneous modes and optimizing the resonator's performance.

[0013] In the first possible design approach, the absolute values ​​of the parasitic mode piezoelectric tensor components of the piezoelectric materials in the first and second piezoelectric layers are the same. This is beneficial for further improving the suppression effect of parasitic modes and further enhancing the performance of the resonator.

[0014] In the first possible design approach, the piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first and second piezoelectric layers have the same sign, and the principal resonant mode piezoelectric tensor components include at least e 34 This allows the main resonant mode of the resonator to remain unchanged or essentially unchanged while suppressing parasitic modes, and greatly reduces the impact of thickness variations in each piezoelectric layer while maintaining a large electromechanical coupling coefficient.

[0015] In one possible design approach, the magnitudes of the piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first and second piezoelectric layers are the same. That is, the absolute values ​​of the piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first and second piezoelectric layers are the same.

[0016] In one possible design approach in the first aspect, the Euler angles of the piezoelectric material in the first piezoelectric layer are (α1, β1, γ1), and the Euler angles of the piezoelectric material in the second piezoelectric layer are (α2, β2, γ2). The rotational transformation relationship between the Euler angles of the piezoelectric material in the first piezoelectric layer and the Euler angles of the piezoelectric material in the second piezoelectric layer is (α, β, γ). (α, β, γ) = (0°±10°, 180°±10°, θ±10°), or (α, β, γ) = (0°±10°, 0°±10°, θ±10°), or (α, β, γ) = (180°±10°, 180°±10°, θ±10°), where θ is any angle between 0° and 360°.

[0017] This not only allows the piezoelectric tensor components (e.g., ep) corresponding to the main resonant mode in both the first and second piezoelectric layers to be... 34 The same properties ensure that the main resonant mode of the resonator remains unchanged or essentially unchanged, thus significantly reducing the impact of thickness variations in each piezoelectric layer while maintaining a large electromechanical coupling coefficient. Simultaneously, it also ensures that the piezoelectric tensor components (e.g., ep) corresponding to parasitic modes in the first and second piezoelectric layers are identical. 11 e 35 The parasitic modes corresponding to the first piezoelectric layer and the second piezoelectric layer are opposite (i.e., opposite numbers), which allows the parasitic modes corresponding to the first piezoelectric layer and the second piezoelectric layer to cancel each other out, effectively suppressing or even eliminating parasitic modes and optimizing the performance of the resonator. In addition, adopting the above configuration can reduce the difficulty of obtaining the first and second piezoelectric layers, reduce the complexity of resonator fabrication, and help reduce costs.

[0018] In the possible design approaches of the first aspect, the values ​​of θ include 0°, 68.867°, 180°, or 320°. For example, (α, β, γ) = (180°±10°, 180°±10°, 0°±10°), or (α, β, γ) = (0°±10°, 0°±10°, 68.867°±10°), or (α, β, γ) = (0°±10°, 180°±10°, 180°±10°). Here, the value of θ is related to the Euler angle of the piezoelectric material in the first piezoelectric layer. For a first piezoelectric layer with a defined Euler angle, θ can be an angle between 0° and 360°, so that the piezoelectric tensor components corresponding to the principal resonant modes in the first and second piezoelectric layers are the same or approximately the same, and that the piezoelectric tensor components corresponding to the parasitic modes in the first and second piezoelectric layers are different (e.g., different or opposite in magnitude). This ensures that parasitic modes are effectively suppressed.

[0019] In one possible design approach, a gap exists between two adjacent second electrodes. A trench is formed in one of the plurality of piezoelectric layers opposite to this gap. This trench extends along the thickness direction of the first electrode and communicates with the gap. By creating the trench, the confinement of the piezoelectric layers can be reduced, which not only helps increase the electromechanical coupling coefficient of the resonator but also helps suppress parasitic modes.

[0020] In one possible design approach, the trench penetrates at least a portion of at least one piezoelectric layer. Optionally, the trench may penetrate a portion of a piezoelectric layer, penetrate a piezoelectric layer, or penetrate two or more piezoelectric layers. Selectively adjusting the depth of the trench can selectively improve the electromechanical coupling coefficient of the resonator.

[0021] In one possible design approach, the first piezoelectric layer is located between the second piezoelectric layer and the first electrode. The second piezoelectric layer has a top surface away from the first piezoelectric layer, and the first piezoelectric layer has a bottom surface away from the second piezoelectric layer, with trenches penetrating both the top and bottom surfaces. This facilitates a further increase in the electromechanical coupling coefficient.

[0022] In one possible design approach, the piezoelectric material of the first piezoelectric layer is the same as that of the second piezoelectric layer. This simplifies the fabrication of the resonator and effectively ensures that the piezoelectric tensor components of the corresponding main resonant modes of the first and second piezoelectric layers are the same, while the piezoelectric tensor components of the corresponding parasitic modes are opposite. This effectively suppresses parasitic modes while ensuring the main resonant modes are maintained.

[0023] In a possible design approach in the first aspect, the piezoelectric material of either the first or second piezoelectric layer includes at least one combination of niobium and lithium, tantalum and lithium, or niobium, tantalum, and lithium. For example, the material of either the first or second piezoelectric layer includes at least one of lithium niobate and lithium tantalate.

[0024] In one possible design approach, the thickness of the first piezoelectric layer is H1, and the thickness of the second piezoelectric layer is H2, wherein 20%H2≤H1≤500%H2. This avoids significantly increasing the thickness of the resonator while effectively suppressing parasitic modes while ensuring the main resonant mode.

[0025] In one possible design approach in the first aspect, the crystal cutting angles of the piezoelectric materials of the first and second piezoelectric layers are X-cut. α1 = 90°, β1 = 90°, γ1 = 195°; α2 = 90°, β2 = -90°, γ2 = -15°. Alternatively, α1 = 90°, β1 = 90°, γ1 = 180°; α2 = 90°, β2 = -90°, γ2 = 0°. α1 = 90°, β1 = 270°, γ1 = 180°; α2 = 90°, β2 = 90°, γ2 = 0°. Alternatively, α1 = 90°, β1 = 90°, γ1 = 68.867°; α2 = 90°, β2 = 90°, γ2 = 0°. The Euler angles of the piezoelectric material in the first piezoelectric layer and the Euler angles of the material in the second piezoelectric layer satisfy the above-mentioned rotational transformation relationship, which can effectively suppress parasitic modes. This embodiment is applicable to resonators where the piezoelectric material of the piezoelectric layer is X-cut.

[0026] In one possible design approach, the crystal cutting angles of the piezoelectric materials in the first and second piezoelectric layers are Y-cut. α1 = 0°, β1 = 90°, γ1 = 180°; α2 = 0°, β2 = -90°, γ2 = 0°. The Euler angles of the piezoelectric materials in the first and second piezoelectric layers satisfy the above rotational transformation relationship, effectively suppressing parasitic modes. This embodiment is suitable for resonators where the piezoelectric material of the piezoelectric layer is Y-cut.

[0027] In one possible design approach, the resonator further includes a substrate located on the side of the first electrode away from the plurality of piezoelectric layers. That is, the resonator can also be a solid-state substrate piezoelectric thin-film resonator.

[0028] In one possible design approach in the first aspect, the substrate material includes at least one of silicon carbide, boron nitride, and diamond.

[0029] In one possible design aspect, the resonator further includes a first busbar and a second busbar. The first and second busbars are disposed on the side of the plurality of piezoelectric layers away from the first electrode. Along the arrangement direction of the plurality of second electrodes, the plurality of second electrodes include alternately arranged first interdigitated electrodes and second interdigitated electrodes. The plurality of first interdigitated electrodes are connected by the first busbar, and the plurality of second interdigitated electrodes are connected by the second busbar. The interdigitation spacing P and the thickness H of the piezoelectric layer satisfy: P / H ≥ 0.5. The width dimension of the first interdigitated electrode is s1, the spacing between adjacent first and second interdigitated electrodes is s2, the interdigitation spacing P = s1 + s2, and the width dimension is parallel to the first electrode and perpendicular to the extension direction of the first interdigitated electrode. This is beneficial for further increasing the electromechanical coupling coefficient of the resonator.

[0030] In a second aspect, a filter is provided, comprising: a plurality of electrically connected resonators. At least one resonator is a resonator as described in any of the design embodiments of the first aspect.

[0031] Because the filter provided in this application embodiment includes a resonator as described in any of the design embodiments of the first aspect, and the multilayer piezoelectric layers in the resonator include a first piezoelectric layer and a second piezoelectric layer, and the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first and second piezoelectric layers have opposite signs, the parasitic stray modes of the resonator are effectively suppressed. When this type of resonator is applied in a filter, it can improve the out-of-band rejection performance of the filter.

[0032] Thirdly, a duplexer is provided, comprising a transmit channel filter and a receive channel filter, at least one of which can be filtered using a filter as described in any of the design schemes in the second aspect.

[0033] Fourthly, a multiplexer is provided, comprising a plurality of transmit channel filters and a plurality of receive channel filters, wherein at least one of the plurality of transmit channel filters, or at least one of the plurality of receive channel filters, may employ a filter as described in any of the design embodiments of the second aspect.

[0034] Fifthly, an electronic device is provided, comprising: a resonator as described in any of the designs in the first aspect, or a filter as described in any of the designs in the second aspect. The electronic device further comprises an amplifier electrically connected to the resonator or the filter. Further, the electronic device may also include a duplexer as described in any of the designs in the third aspect or a multiplexer as described in any of the designs in the fourth aspect, wherein the filter, duplexer, or multiplexer may be electrically connected to the amplifier.

[0035] The technical effects of any of the design methods in the third to fifth aspects can be found in the technical effects of different design methods in the first aspect, and will not be repeated here. Attached Figure Description

[0036] Figure 1 is an architectural diagram of an electronic device provided in an embodiment of this application;

[0037] Figure 2 is a partial structural diagram of an electronic device provided in an embodiment of this application;

[0038] Figure 3 is a partial structural diagram of a filter provided in an embodiment of this application;

[0039] Figure 4 is a partial structural diagram of a resonator provided in an embodiment of this application;

[0040] Figure 5 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0041] Figure 6 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0042] Figure 7a is a partial structural diagram of another resonator provided in an embodiment of this application;

[0043] Figure 7b is a partial structural diagram of another resonator provided in an embodiment of this application;

[0044] Figure 8a is an admittance curve near the SH1 main resonant mode frequency of the resonator shown in Figure 4;

[0045] Figure 8b shows another admittance curve near the SH1 main resonant mode frequency of the resonator shown in Figure 4;

[0046] Figure 8c is an admittance curve near the SH1 main resonant mode frequency of the resonator shown in Figure 7a;

[0047] Figure 8d is another admittance curve near the SH1 main resonant mode frequency of the resonator shown in Figure 7a;

[0048] Figure 9 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0049] Figure 10 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0050] Figure 11a is a partial structural diagram of another resonator provided in an embodiment of this application;

[0051] Figure 11b is a partial structural diagram of another resonator provided in an embodiment of this application;

[0052] Figure 12 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0053] Figure 13 is a diagram illustrating the Euler angle rotation transformation process of a piezoelectric material in a piezoelectric layer provided in an embodiment of this application.

[0054] Figure 14 is a diagram illustrating the Euler angle rotation transformation process of another piezoelectric layer provided in an embodiment of this application.

[0055] Figure 15 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0056] Figure 16 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0057] Figure 17 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0058] Figure 18 is a partial structural diagram of another resonator provided in an embodiment of this application;

[0059] Figure 19 is a top view of a plurality of second electrodes provided in an embodiment of this application;

[0060] Figure 20 shows the admittance curve and vibration displacement distribution near the main resonant mode frequency of SH1 provided in an embodiment of this application.

[0061] Figure 21 shows the admittance curve and vibration displacement distribution near the main resonant mode frequency of SH1 provided in another embodiment of this application.

[0062] Figure 22 shows the admittance curve and vibration displacement distribution near the main resonant mode frequency of SH1 in another embodiment of this application;

[0063] Figure 23 shows the admittance curve and vibration displacement distribution near the main resonant mode frequency of SH1 in another embodiment of this application;

[0064] Figure 24 shows the admittance curve and vibration displacement distribution near the main resonant mode frequency of SH1 in another embodiment of this application;

[0065] Figure 25 shows the admittance curve and vibration displacement distribution near the main resonant mode frequency of SH1 in another embodiment of this application;

[0066] Figure 26 is an admittance curve near the main resonant mode frequency of SH1 provided in an embodiment of this application;

[0067] Figure 27 is an admittance curve near the main resonant mode frequency of SH1 provided in another embodiment of this application;

[0068] Figure 28 is a schematic diagram of a filter structure provided in an embodiment of this application;

[0069] Figure 29 shows the admittance curves of the various resonators shown in Figure 28 and the filter bandpass. Detailed Implementation

[0070] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application are within the scope of protection of this application.

[0071] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. "At least one" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, and c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. "a and / or b" includes the following three combinations: only a, only b, and a combination of a and b. "Spacing" refers, for example, to the minimum distance between two adjacent structures.

[0072] Furthermore, to facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" are not necessarily different. Meanwhile, in the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is being used as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present related concepts in a concrete manner for ease of understanding.

[0073] In describing some embodiments, the term "connection" and its derivative expressions are used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0074] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable range of deviation for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.

[0075] In this application embodiment, the terms "upper," "lower," "left," and "right" are not limited to the orientation of the components schematically placed in the accompanying drawings. It should be understood that these directional terms can be relative concepts used for description and clarification, and can vary accordingly depending on the orientation of the components in the accompanying drawings. In the drawings, for clarity, the thickness of layers and regions is exaggerated, and the dimensional proportions between the parts in the illustrations do not reflect actual dimensional proportions. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, exemplary embodiments should not be construed as being limited to the shapes of the areas shown in this application, but rather include shape deviations due to, for example, manufacturing. For example, an etched area shown as rectangular would typically have a curved feature. Therefore, the areas shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0076] Furthermore, the architecture and scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of architecture and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0077] Before introducing the structures that can be implemented in the embodiments of this application, let's first introduce the technical terms involved in the embodiments of this application.

[0078] Piezoelectric effect: This includes the direct piezoelectric effect and the inverse piezoelectric effect. The direct piezoelectric effect refers to the change in polarization of a piezoelectric material when subjected to mechanical force; while the inverse piezoelectric effect refers to the deformation of a piezoelectric material when an external electric field is applied. The piezoelectric effect is mainly caused by the anisotropy of the crystal structure of piezoelectric materials and their polarization.

[0079] Main resonant mode and parasitic modes: The parasitic resonant frequencies generated by a resonator may be located close to the main resonant frequency. Parasitic resonances can affect the main resonant mode, thereby affecting the filter's in-band insertion loss performance and out-of-band rejection performance. The parasitic resonances of a resonator are commonly referred to as parasitic modes. When parasitic modes fall near the main resonant mode, for example, near the main resonant mode's resonance point and anti-resonant point, they will affect the filter's in-band insertion loss performance and out-of-band rejection performance.

[0080] Piezoelectric coupling factor Kt 2 Kt is a key parameter of the resonator, representing the electromechanical coupling coefficient. 2It can reflect the conversion efficiency between mechanical energy and electrical energy, and the electromechanical coupling coefficient Kt of the resonator. 2 This determines the relative frequency width of the resonator's anti-resonance frequency and resonant frequency. For example, when a resonator is used in filter design, this relative frequency width directly determines the filter's bandwidth. The electromechanical coupling coefficient Kt can be considered as... 2 The larger the value, the greater the bandwidth of the filter built using the trapezoidal structure, and the better its performance.

[0081] Electromechanical coupling coefficient component k xy 2 For a single-crystal piezoelectric material, it possesses a fourth-order elastic tensor c, a third-order piezoelectric tensor e, and a second-order dielectric tensor ε. According to a right-hand rectangular coordinate system, it has elastic tensor components c... ijkl piezoelectric tensor component e ijk ε, dielectric tensor component ij Where i,j,k,l={1,2,3}. Due to the symmetry of single-crystal structures, for example c 1323 =c 3132 This simplifies the component order, defining {23,32}→4, {13,31}→5, {12,21}→6, for example, c 1323 =c 3132 →c54, then there is an elastic tensor component c xy (6*6), piezoelectric tensor component e ix (3*6), dielectric tensor component ε ij (3*3), where i,j={1,2,3}, x,y={1,2,3,4,5,6}. Electromechanical coupling coefficient component k xy 2 It is calculated from the elastic tensor components, piezoelectric tensor components, and dielectric tensor components of the material, and the formula is:

[0082] Among them, x={1,2,3}, y={1,2,3,4,5,6}, ε xx S For the dielectric tensor components under constant strain, c yy E These are the elastic tensor components under a fixed electric field strength.

[0083] The following explains the calculation methods and formulas for each elastic tensor component, piezoelectric tensor component, and dielectric tensor component at different Euler angles in different crystals.

[0084] For piezoelectric materials with an Euler angle of (0, 0, 0), taking LN (Lithium Niobate (LiNbO3)) as an example...

[0085] c E11 =2.03, c E 12 =0.53, c E 13 =0.75, c E 14 =0.09, c E 44 =0.60, c E 33 =2.43, c E 22 =c E 11 c E 23 = c E 13 c E 24 =-c E 14 c E 55 =c E 44 c E 56 =c E 14 c E 66 =(c E 11 -c E 12 ) / 2, unit is *10 11 N / m 2 ;

[0086] e 15 =3.70, e 16 =-2.53,e 31 =0.19, e 33 =1.31, e 21 =e 16 e 22 =-e 16 e 24 =e 15 e 32 =e 31 The unit is C / m 2 ;

[0087] ε S 11 =43.6*ε0, ε S 33 =29.2*ε0, ε S 22 =ε S 11 Where ε0 is the vacuum permittivity, 8.85 × 10⁻⁶.-12 F / m.

[0088] The remaining components can be obtained through tensor symmetry; components without values ​​are zero. The components are simplified representations; for a fourth-order elastic tensor component c... E ijkl Third-order piezoelectric tensor component e ijk This can be expanded accordingly.

[0089] For a piezoelectric material with Euler angles (α, β, γ) and crystal orientation, its corresponding elastic tensor component c E pqrs ', piezoelectric tensor component e pqr ε, dielectric tensor component S pq ' can be calculated using the following formula: c E pqrs '=c E ijkl A ip A jq A kr A ls e pqr ' = e ijk A ip A jq A kr ; ε S pq ' = ε S ij A ip A jq ;

[0090] The formula uses Einstein's summation convention, where the 3x3 matrix A is:

[0091] electromechanical coupling coefficient Kt 2 and electromechanical coupling coefficient component k xy 2 Relationship: Electromechanical coupling coefficient Kt 2 From the electromechanical coupling coefficient component k xy 2 The mode is determined by the specific resonator structure and the excitation mode. Generally, the k-mode corresponds to the main resonant mode of the resonator. xy 2 The larger the value, the greater the value of the resonator's Kt. 2 The larger the value, the greater the value. For example, when LN is chosen as the piezoelectric material, the larger the maximum electromechanical coupling coefficient component k of LN. xy 2 It can reach 0.9253. Resonators that utilize this component to generate the main resonant mode possess relatively large overall electromechanical coupling performance; for example, the electromechanical coupling coefficient Kt of the resonator...2 It can reach 25%. Furthermore, generally speaking, the electromechanical coupling coefficient component k corresponding to the main resonant mode... xy 2 The larger the value, the more the remaining electromechanical coupling coefficient components k xy 2 The smaller the value, the larger the electromechanical coupling coefficient and the smaller the parasitic modes of the resonator.

[0092] Given a resonator structure, one resonant mode corresponds to one electromechanical coupling coefficient component k. xy 2 For example, the maximum electromechanical coupling coefficient component k of LN xy 2 It can include k 16 2 k 15 2 k 34 2 k 35 2 Excite these maximum electromechanical coupling coefficient components k xy 2 The generated modes are the dominant resonant modes, while the modes generated by the other electromechanical coupling coefficient components can be heterogeneous modes. For example, in XBAR, the excitation of the maximum electromechanical coupling coefficient component k... 16 2 This generates the zero-order shear horizontal mode (SH0 mode), the main resonant mode; in XBAR, the excitation of the maximum electromechanical coupling coefficient component k 15 2 This generates the first-order anti-symmetry mode (A1 mode) of the main resonant mode; in YBAR, the excitation of the maximum electromechanical coupling coefficient component k 34 2 This generates the first-order shear horizontal mode (SH1 mode) of the main resonant mode.

[0093] Quality factor Q represents the energy efficiency of a device, that is, the ratio of the total energy received by the device to the energy dissipated within one vibration cycle. In filter design, the electromechanical coupling coefficient Kt of the resonator that constitutes the filter... 2 Both the quality factor (Q) and the Q value are important parameters.

[0094] Euler angle of piezoelectric materials: Euler angle characterizes the relative rotation angle between the direction of the resonator finger extension and the X or Y direction of the original piezoelectric crystal structure in the wafer plane, which is perpendicular or parallel to the direction of the resonator finger extension.

[0095] Admittance: In power electronics, admittance is defined as the reciprocal of impedance, denoted by Y, and its unit is Siemens (S). Like impedance, admittance is also a complex number, consisting of a real part (conductance G) and an imaginary part (susceptance B): Y = G + jB.

[0096] Admittance curve abs and admittance curve Re: Admittance curve abs(Y) = |Y|, which is the magnitude (also called amplitude) of Y, representing the overall response of the resonator. Re(Y) is the real part of Y, i.e., the conductance G, representing the loss of the resonator.

[0097] RaR range: The frequency range around the resonant frequency fr and the anti-resonant frequency fa. For example, the RaR range is (fr-(fa-fr)) to (fa+(fa-fr)).

[0098] Electromechanical coupling R-aR: Based on the relative bandwidth of the resonant frequency fr and the anti-resonant frequency fa, it represents the electromechanical coupling coefficient of the resonator. For example, the R-aR of the resonator should be comparable to the relative bandwidth of the target filter. Where R-aR = (fa - fr) / ((fa + fr) / 2).

[0099] The electronic device, filter, and resonator provided in the embodiments of this application will be described below with reference to the accompanying drawings.

[0100] This application provides an electronic device, which includes, but is not limited to, radio frequency front-ends, filtering and amplification modules, and may also include mobile phones, tablets, smart wearable products (e.g., smartwatches, smart bracelets), virtual reality (VR) devices, augmented reality (AR) devices, drones, and other terminal devices, or may be base stations, televisions, routers, automobiles, mobile phones, etc. This application does not impose any special limitations on the specific form of the above-mentioned electronic device.

[0101] In an electronic device such as the one described above, as shown in FIG1, the electronic device 100 may include a filter 200, which can effectively filter out a specific frequency point or frequencies other than that frequency point in a signal to obtain a signal of a specific frequency, or eliminate a signal after a specific frequency, so as to improve the working performance of the electronic device 100.

[0102] Figure 2 shows a partial circuit diagram of some electronic devices 100. As shown in Figure 2, the electronic device 100 includes a receiver 600, a transmitter 700, an antenna 500, and a baseband chip 800. The antenna 500 is electrically connected to the receiver 600 and the transmitter 700 respectively via a switch 900, and the receiver 600 and the transmitter 700 are electrically connected to the baseband chip 800 respectively.

[0103] The receiver 600 shown in Figure 2 includes a filter 60a and a filter 60c. A low-noise amplifier 60b is electrically connected between filters 60a and 60c. Filter 60c is electrically connected to a buffer 60e via a mixer 60d. Buffer 60e is electrically connected to a voltage-controlled oscillator 60f. Figure 2 is only an exemplary receiver; electronic components can be added or removed from this circuit structure.

[0104] The transmitter 700 shown in Figure 2 includes a power amplifier (PA) 70b, which is electrically connected to a filter 70a and a driver 70c, respectively. The driver 70c is electrically connected to a voltage-controlled oscillator 70d. Similarly, Figure 2 is only an exemplary transmitter, and electronic components can be added or removed from this circuit structure.

[0105] For example, in the transmitter 700 shown in Figure 2, the filter can effectively filter out a specific frequency point or frequencies other than that amplified by the power amplifier, or the filter can filter out noise from the low-noise amplifier.

[0106] As shown in Figures 1 and 3, the filter 200 includes a resonator 300. Further, as shown in Figure 3, the filter 200 may include multiple resonators 300 connected in series, or multiple resonators 300 connected in parallel, or a combination of resonators 300 connected in series and resonators 300 connected in parallel.

[0107] Figures 4 to 7b illustrate the local structure of a resonator.

[0108] In some examples, as shown in FIG4, the resonator 300 includes a first electrode 10, a piezoelectric layer 20, and a plurality of second electrodes 30. The first electrode 10 is, for example, in the form of a thin film. The piezoelectric layer 20 is located on the first electrode 10, and the plurality of second electrodes 30 are located on the side of the piezoelectric layer 20 away from the first electrode 10. Specifically, as shown in FIG4, the first electrode 10, the piezoelectric layer 20, and the plurality of second electrodes 30 are sequentially stacked along the thickness direction of the first electrode, and further, the plurality of second electrodes 30 are sequentially spaced apart. The arrangement direction of the plurality of second electrodes 30 intersects (e.g., is perpendicular to) their extension direction. The plurality of second electrodes 30 are arranged side by side on the piezoelectric layer 20, rather than being stacked on the piezoelectric layer 20 along the thickness direction of the first electrode.

[0109] In other examples, as shown in Figure 5, the resonator 300 includes a substrate 40, a first electrode 10, a piezoelectric layer 20, and a plurality of second electrodes 30. The arrangement of the first electrode 10, the piezoelectric layer 20, and the plurality of second electrodes 30 is the same as that shown in one type of resonator 300 in Figure 4, and will not be repeated here. Further, as shown in Figure 5, the substrate 40 is located on the side of the first electrode 10 away from the piezoelectric layer 20 and is in contact with the surface of the first electrode 10 on the side away from the piezoelectric layer 20.

[0110] In some other examples, as shown in Figure 6, the resonator 300 includes a substrate 40, a first electrode 10, a piezoelectric layer 20, and a plurality of second electrodes 30. The arrangement of the first electrode 10, the piezoelectric layer 20, and the plurality of second electrodes 30 is the same as that shown in one type of resonator 300 in Figure 4, and will not be repeated here. Further, as shown in Figure 6, the first electrode 10 has a bottom surface away from the second electrode 20; a cavity 401 is formed in the substrate 40, which exposes at least a portion of the bottom surface of the first electrode 10, such that at least a portion of the bottom surface of the first electrode 10 is used to enclose the cavity 401, and at least a portion of the first electrode 10 is disposed between the cavity 401 and the piezoelectric layer 20.

[0111] In some other examples, as shown in FIG7a, the resonator 300 includes a substrate 40, a first electrode 10, a piezoelectric layer 20, and a plurality of second electrodes 30. The arrangement of the first electrode 10, the piezoelectric layer 20, and the plurality of second electrodes 30 is the same as that shown in FIG4 for one type of resonator 300, and will not be repeated here. Further, as shown in FIG7a, the substrate 40 is located on the side of the first electrode 10 away from the piezoelectric layer 20; the resonator 300 also includes a dielectric layer 50 disposed between the substrate 40 and the first electrode 10, the dielectric layer 50 being in contact with the surface of the first electrode 10 away from the piezoelectric layer 20 and with the surface of the substrate 40 close to the first electrode 10. Of course, other functional layer structures can also be stacked between the substrate 40 and the first electrode 10. For example, as shown in FIG7b, the resonator 300 also includes a Bragg reflector structure 80 disposed between the substrate 40 and the dielectric layer 50.

[0112] Here, the structures shown in Figures 4 to 7b can be used for bulk acoustic wave resonators. The main working principle of bulk acoustic wave resonators is to use the piezoelectric effect characteristics of piezoelectric materials to convert the input signal of the radio wave into mechanical energy using input and output transducers. After processing, the mechanical energy is converted into an electrical signal to achieve the goal of filtering unnecessary signals and noise and improving reception quality.

[0113] In the structures shown in Figures 4 to 7b, during operation, the first electrode 10 may not be connected to an electrical signal, while the second electrode 30 may be subjected to an alternating voltage of a certain frequency. This generates an electric field E (also known as a vertical electric field E) between the first electrode 10 and the second electrode 30 along the thickness direction of the first electrode. The piezoelectric layer 20 can utilize this vertical electric field E to form a piezoelectric effect. The structures shown in Figures 4 to 7b utilize the vertical electric field E to excite the piezoelectric layer 20 to resonate, thereby generating a conversion between electrical energy and mechanical energy.

[0114] It is understood that the structures shown in Figures 4 to 7b all generate an electric field in the thickness direction of the first electrode to excite resonance. Therefore, for example, the structures shown in Figures 4 to 7b can all be called YBARs. Among them, the structure shown in Figure 4 can also be called a suspended thin-film piezoelectric thin-film resonator, the structures shown in Figures 5, 7a, and 7b can also be called solid-substrate piezoelectric thin-film resonators, and the structure shown in Figure 6 can also be called a cavity-type suspended piezoelectric thin-film resonator.

[0115] Currently, in YBARs, several different types of parasitic modes have emerged near the resonant frequency fr and anti-resonant frequency fa. For example, taking the structures shown in Figures 4 and 7a as examples, in the structure shown in Figure 4, when the crystal cutting angle of the piezoelectric material in the piezoelectric layer 20 is X-cut, Figures 8a and 8b respectively show an admittance curve near the SH1 main resonant mode frequency of the structure shown in Figure 4; in the structure shown in Figure 7a, when the crystal cutting angle of the piezoelectric material in the piezoelectric layer 20 is X-cut, Figure 8c shows an admittance curve near the SH1 main resonant mode frequency of the structure shown in Figure 7a; and in the structure shown in Figure 7a, when the crystal cutting angle of the piezoelectric material in the piezoelectric layer 20 is Y-cut, Figure 8d shows an admittance curve near the SH1 main resonant mode frequency of the structure shown in Figure 7a. Where, e 34 The piezoelectric tensor component corresponding to the main resonant mode (SH1 film).

[0116] In Figure 8a, the third-order vertical shear mode (SV mode) generated between the resonant point of the main resonant mode and the anti-resonant point of the main resonant mode is considered as a parasitic miscellaneous mode. This third-order SV mode is the electromechanical coupling coefficient component k excited by the electric field along direction 3. 35 2 Generated. Among them, e 35 These are the piezoelectric tensor components corresponding to the third-order SV mode.

[0117] In Figure 8b, parasitic modes are generated near the resonant point of the main resonant mode and the anti-resonant point of the main resonant mode. These parasitic modes include, for example, SH0 modes (or third-order SH0 modes) and A1 modes. Wherein, e 16 e is the piezoelectric tensor component corresponding to the SH0 mode. 35 This represents the piezoelectric tensor component corresponding to the A1 mode.

[0118] In Figure 8c, parasitic modes are generated near the resonant point and anti-resonant point of the main resonant mode. These parasitic modes include, for example, a zero-order symmetry mode (S0 mode) and an A1 mode. The S0 mode is the component k of the electromechanical coupling coefficient of the electric field excitation along direction 1. 11 2 The generated A1 mode is the electromechanical coupling coefficient component k of the electric field excitation along direction 1. 35 2 Generated. Among them, e 11 e is the piezoelectric tensor component corresponding to the S0 mode. 35 This represents the piezoelectric tensor component corresponding to the A1 mode.

[0119] In Figure 8d, the S0 mode generated between the resonant point of the main resonant mode and the anti-resonant point of the main resonant mode is considered as a parasitic miscellaneous mode. This S0 mode is the component k of the electromechanical coupling coefficient excited by the electric field along direction 1. 31 2 Generated. Among them, e 31 This represents the piezoelectric tensor component corresponding to the S0 mode.

[0120] In this embodiment, direction 1 can be understood as a direction perpendicular to the thickness direction of the first electrode 10 and perpendicular to the extension direction of the second electrode 30; direction 2 can be understood as a direction parallel to the extension direction of the second electrode 30; and direction 3 can be understood as the thickness direction of the first electrode 10. In X-cut, "X" represents the X-direction of the piezoelectric material. X-cut can be used to indicate that the X-direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer 20. The propagation direction in the definition of the piezoelectric material tangential direction is parallel to the surface of the piezoelectric layer and perpendicular to the extension direction of the second electrode 30. In Y-cut, "Y" represents the Y-direction of the piezoelectric material. Y-cut can be used to indicate that the Y-direction of the piezoelectric material is in the same direction as the thickness direction of the piezoelectric layer 20.

[0121] Based on Figures 4 and 7a, although the resonator using the SH1 main resonant mode has a large electromechanical coupling coefficient and can be applied in devices with a larger passband bandwidth, many other modes will be excited (e.g., A1 mode, S0 mode, etc.), which will appear as parasitic modes. These parasitic modes will affect the passband insertion loss performance and out-of-band rejection performance of the device (e.g., filter).

[0122] Based on this, embodiments of this application also provide some resonators that not only possess high electromechanical coupling coefficients but also effectively suppress parasitic modes, thus optimizing the resonator's performance. These resonators are suitable for various thin-film shear body acoustic resonators, especially YBARs. Figures 9 to 12 illustrate partial structures of one such resonator.

[0123] In some examples, as shown in FIG9, the resonator 300 may include a first electrode 10, a plurality of piezoelectric layers 20, and a plurality of second electrodes 30. The first electrode 10 is, for example, in the form of a thin film. The plurality of piezoelectric layers 20 are located on the first electrode 10. Further, the plurality of piezoelectric layers 20 are stacked along the thickness direction of the first electrode, that is, the plurality of piezoelectric layers 20 are stacked on the first electrode 10. The plurality of second electrodes 30 are located on the side of the plurality of piezoelectric layers 20 away from the first electrode 10, and are arranged sequentially at intervals.

[0124] Among the aforementioned plurality of second electrodes 30, the widths (i.e., the dimensions in their arrangement direction) of different second electrodes 30 are, for example, equal, and the spacing between any two adjacent second electrodes 30 is, for example, equal.

[0125] For example, the first electrode 10 can be made of any possible conductive metal, including but not limited to aluminum (Al), copper (Cu), tungsten (W), molybdenum (Mo), ruthenium (Ru), platinum (Pt), chromium (Cr), etc. Alternatively, conductive metals with high acoustic impedance, including but not limited to W, Ru, Mo, Pt, etc., can be selected. These metals with high acoustic impedance help increase the electromechanical coupling coefficient and improve the quality factor, further enhancing the performance of the resonator. The second electrode 30 can be made of any possible conductive metal, including but not limited to Al, Cu, W, Mo, Ru, Pt, Cr, titanium (Ti), etc.

[0126] For example, the first electrode 10 and the second electrode 30 can be made of the same conductive metal or different conductive metals.

[0127] In other examples, as shown in FIG10, the resonator 300 may further include a substrate 40 located on the side of the first electrode 10 away from the piezoelectric layer 20 and in contact with the surface of the first electrode 10 on the side away from the piezoelectric layer 20. Exemplarily, the substrate 40 may be a high-velocity substrate, for example, any one or a combination of silicon carbide (SiC), diamond, and boron nitride (BN).

[0128] In some other examples, as shown in Figures 11a, 11b, and 12, the resonator 300 may also include a dielectric layer 50 located between the substrate 40 and the first electrode 10. Exemplarily, the material of the dielectric layer 50 includes, but is not limited to, silicon oxide (SiO2). Here, the thickness of the dielectric layer 50 can be selected based on the vibration intensity requirements of the resonator 300 and the electromechanical coupling coefficient.

[0129] In some other examples, as shown in Figure 11b, the resonator 300 may also include a Bragg reflection structure 80 located between the substrate 40 and the dielectric layer 50. Exemplarily, the Bragg reflection structure 80 comprises a multilayered stacked film structure, for example, formed by alternating stacks of high acoustic impedance materials and low acoustic impedance materials. The high acoustic impedance materials include, but are not limited to, W, hafnium oxide (HfO2), Mo, etc.; the low acoustic impedance materials include, but are not limited to, silicon oxide, etc. These alternating stacked structures create a Bragg reflection effect for acoustic waves that may propagate downwards, suppressing downward energy leakage and improving the Q value and electromechanical coupling coefficient of the resonator.

[0130] The arrangement of the first electrode 10, multiple piezoelectric layers 20 and multiple second electrodes 30 in Figures 10, 11a, 11b and 12 is the same as that in Figure 9, and will not be described again here.

[0131] For example, in the resonators shown in Figures 9 to 12, the number of piezoelectric layers 20 can be selected according to actual needs. For instance, Figures 9, 10, and 11a illustrate two piezoelectric layers 20, and Figure 12 illustrates four piezoelectric layers 20. Of course, the number of piezoelectric layers 20 can also be more. Optionally, the number of piezoelectric layers 20 is an even number.

[0132] In the aforementioned plurality of piezoelectric layers 20, two adjacent piezoelectric layers 20 are respectively a first piezoelectric layer 201 and a second piezoelectric layer 202. Here, "two adjacent piezoelectric layers 20" means that the first piezoelectric layer 201 and the second piezoelectric layer 202 are in direct contact, and no other piezoelectric layer 20 is disposed between the first piezoelectric layer 201 and the second piezoelectric layer 202. For example, as shown in Figures 9 to 12, the first piezoelectric layer 201 is located between the second piezoelectric layer 202 and the first electrode 10; the surface of the first piezoelectric layer 201 away from the first electrode 10 is in direct contact with the surface of the second piezoelectric layer 202 near the first electrode 10, and no other structure is disposed between them.

[0133] Furthermore, in Figures 9 to 11a, "two adjacent piezoelectric layers 20" refers to the two piezoelectric layers 20 included in the resonator 300. In Figure 12, along the direction from the first electrode 10 to the second electrode 30, the four piezoelectric layers 20 included in the resonator 300 can be the first piezoelectric layer 20, the second piezoelectric layer 20, the third piezoelectric layer 20, and the fourth piezoelectric layer 20, respectively; "two adjacent piezoelectric layers 20" can refer to the first piezoelectric layer 20 and the second piezoelectric layer 20, or the second piezoelectric layer 20 and the third piezoelectric layer 20, or the third piezoelectric layer 20 and the fourth piezoelectric layer 20.

[0134] The parasitic mode piezoelectric tensor components of the piezoelectric materials in the first piezoelectric layer 201 and the second piezoelectric layer 202 are different in magnitude. That is, the parasitic mode piezoelectric tensor component of the piezoelectric material in one of the first piezoelectric layers 201 and the second piezoelectric layer 202 is larger than that in the other piezoelectric layer 201 and the second piezoelectric layer 202. When the resonator 300 includes more than two piezoelectric layers 20, the parasitic mode piezoelectric tensor components of the piezoelectric materials in any two adjacent piezoelectric layers 20 are different in magnitude.

[0135] In this way, in the first piezoelectric layer 201 and the second piezoelectric layer 202, the one with the smaller parasitic mode piezoelectric tensor component can be coupled with the one with the larger parasitic mode piezoelectric tensor component, thereby reducing the parasitic miscellaneous modes corresponding to both the first piezoelectric layer 201 and the second piezoelectric layer 202, achieving the effect of suppressing parasitic miscellaneous modes, and improving the performance of the resonator 300.

[0136] In some examples, the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 have opposite signs. That is, the polarities of the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 are opposite. When the resonator 300 includes more than two piezoelectric layers 20, the parasitic mode piezoelectric tensor components of the piezoelectric materials of any two adjacent piezoelectric layers 20 have opposite signs.

[0137] In this way, the parasitic modes corresponding to the first piezoelectric layer 201 and the parasitic modes corresponding to the second piezoelectric layer 202 can be canceled out, effectively suppressing or even eliminating parasitic modes and improving the performance of the resonator 300.

[0138] Furthermore, by way of example, the absolute values ​​of the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same. Correspondingly, the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 are opposite (i.e., opposite numbers to each other).

[0139] This helps to improve the cancellation effect between the parasitic modes corresponding to the first piezoelectric layer 201 and the parasitic modes corresponding to the second piezoelectric layer 202, which is conducive to further improving the suppression effect of parasitic modes and further enhancing the performance of the resonator 300.

[0140] In some examples, the parasitic modal piezoelectric tensor components include at least one or more of the following: e 11 e 16 e 31 and e 35 .

[0141] For example, when the resonator 300 is a suspended thin-film piezoelectric thin-film resonator, taking the structure shown in Figure 9 as an example, the parasitic modes of the resonator 300 include third-order SV modes. Correspondingly, the piezoelectric material of the first piezoelectric layer 201 has a piezoelectric tensor component e. 35 The piezoelectric material of the second piezoelectric layer 202 has a piezoelectric tensor component e. 35 The piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 35 Conversely, for example, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201. 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 35 The signs are opposite and the absolute values ​​are the same.

[0142] Alternatively, the parasitic modes of the resonator 300 include SH0 and A1 modes, and correspondingly, the piezoelectric material of the first piezoelectric layer 201 has a piezoelectric tensor component e.16 and e 35 The piezoelectric material of the second piezoelectric layer 202 has a piezoelectric tensor component e. 16 and e 35 The piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 16 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 16 The piezoelectric tensor components e of the piezoelectric material of the first piezoelectric layer 201 have opposite signs and different absolute values. 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 35 Conversely; that is, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 35 The signs are opposite and the absolute values ​​are the same.

[0143] For example, when the resonator 300 is a solid-state substrate piezoelectric thin-film resonator, and the crystal cutting angle of the piezoelectric material of the first piezoelectric layer 201 and the second piezoelectric layer 202 is X-cut, taking the structure shown in Figure 11a as an example, the parasitic modes of the resonator 300 include S0 mode and A1 mode. Correspondingly, the piezoelectric material of the first piezoelectric layer 201 has a piezoelectric tensor component e. 11 and e 35 The piezoelectric material of the second piezoelectric layer 202 has a piezoelectric tensor component e. 11 and e 35 The piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 11 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 11 Conversely, that is, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 11 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 11 The piezoelectric tensor components e of the piezoelectric material of the first piezoelectric layer 201 have opposite signs and the same absolute value. 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 35 Conversely, that is, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 35 The signs are opposite and the absolute values ​​are the same.

[0144] For example, when the resonator 300 is a solid-state substrate piezoelectric thin-film resonator, and the crystal cutting angle of the piezoelectric material of the first piezoelectric layer 201 and the second piezoelectric layer 202 is Y-cut, taking the structure shown in Figure 11a as an example, the parasitic modes of the resonator 300 include the S0 mode. Correspondingly, the piezoelectric material of the first piezoelectric layer 201 has a piezoelectric tensor component e. 31 The piezoelectric material of the second piezoelectric layer 202 has a piezoelectric tensor component e. 31 The piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 31 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 31 Conversely, that is, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 201 31 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 202 31 The signs are opposite and the absolute values ​​are the same.

[0145] In some embodiments, the piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 have the same sign, and the principal resonant mode piezoelectric tensor components include at least e 34 In the principal resonant mode, the piezoelectric tensor component is e 34 In this case, the main resonant mode of resonator 300 is the SH1 film.

[0146] For example, the absolute values ​​of the piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same. Correspondingly, the piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same.

[0147] This allows the main resonant mode of the resonator 300 to remain unchanged or essentially unchanged while suppressing parasitic modes, and greatly reduces the impact of thickness variations in each piezoelectric layer 20 while maintaining a large electromechanical coupling coefficient.

[0148] In some embodiments, the Euler angles of the piezoelectric material of the first piezoelectric layer 201 are (α1, β1, γ1), the Euler angles of the piezoelectric material of the second piezoelectric layer 202 are (α2, β2, γ2), and the rotational transformation relationship between the Euler angles of the piezoelectric material of the first piezoelectric layer 201 and the Euler angles of the piezoelectric material of the second piezoelectric layer 202 is (α, β, γ). Wherein, (α, β, γ) = (0°±10°, 180°±10°, θ±10°), or (α, β, γ) = (0°±10°, 0°±10°, θ±10°), or (α, β, γ) = (180°±10°, 180°±10°, θ±10°), where θ is any angle between 0° and 360°. Here, the value of θ is related to the Euler angle of the piezoelectric material of the first piezoelectric layer 201. For the first piezoelectric layer 201 with a definite Euler angle, θ can be an angle between 0° and 360°, so that the piezoelectric tensor components of the corresponding main resonant modes in the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same or approximately the same, and that the piezoelectric tensor components of the corresponding parasitic modes in the first piezoelectric layer 201 and the second piezoelectric layer 202 are different (e.g., different or opposite in magnitude).

[0149] Optionally, the value of θ can be 0°, 68.867°, 180°, or 320°, etc. For example, if the Euler angle of the piezoelectric material of the first piezoelectric layer 201 is (90°, 90°, 0°), then θ is 68.867°; if the Euler angle of the piezoelectric material of the first piezoelectric layer 201 is (0°, 90°, 20°), then θ is 320°. Of course, the value of θ is not limited to this; the value of θ can also be selected and set according to the Euler angle (or crystal orientation) of the piezoelectric material of the first piezoelectric layer 201.

[0150] The rotational transformation relationship described above is allowed to have a certain margin of error, with an accuracy of <±10°. For example, the rotational transformation relationship is (α, β, γ) = (0°±10°, 180°±10°, 180°±10°). Further, the rotational transformation relationship (α, β, γ) can be: (0°, 180°, 180°), (5°, 185°, 185°), (5°, 180°, 190°), or (10°, 190°, 180°), etc.

[0151] Alternatively, the above rotational transformation relationship can be (α, β, γ) = (0° ± 10°, 0° ± 10°, 68.867° ± 10°). Further, the rotational transformation relationship (α, β, γ) can be: (0°, 0°, 68.867°), (5°, 0°, 70°), (5°, 10°, 78.867°), or (10°, 0°, 68.867°), etc.

[0152] Alternatively, the above rotational transformation relationship can be (α, β, γ) = (180° ± 10°, 180° ± 10°, 0° ± 10°). Further, the rotational transformation relationship (α, β, γ) can be: (180°, 180°, 0°), (185°, 180°, 5°), (190°, 180°, 5°), or (190°, 180°, 10°), etc.

[0153] Understandably, given that the Euler angles of the piezoelectric material in the first piezoelectric layer 201 are determined, the Euler angles of the piezoelectric material in the first piezoelectric layer 201 can be obtained by rotating them according to the aforementioned rotation transformation relationship (α, β, γ) (which can also be understood as rotating the crystal orientation or tangential orientation of the piezoelectric material in the first piezoelectric layer 201). Alternatively, given that the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are determined, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 can be obtained by rotating them according to the rotation transformation relationship (-γ, -β, -α) (which can also be understood as rotating the crystal orientation or tangential orientation of the piezoelectric material in the second piezoelectric layer 202).

[0154] For example, consider a case where the Euler angles of the piezoelectric material in the first piezoelectric layer 201 are determined and are (90°, -90°, -15°). The crystal orientation of the piezoelectric material in the first piezoelectric layer 201 is shown by the arrows in Figures 13(a) and 14(a). In the coordinate system shown in Figures 13(a) and 14(a), the X-axis refers, for example, to the arrangement direction of the plurality of second electrodes 30, the Y-axis extends, for example, along the extension direction of the second electrodes 30, and the Z-axis refers, for example, to the thickness direction of the first electrode 10.

[0155] With (α, β, γ) = (0°, 180°, 180°), as shown in Figure 13(a), the crystal orientation of the piezoelectric material in the first piezoelectric layer 201 is first rotated by 0° along the Z-axis shown in Figure 13(a); combining Figures 13(a) and (b), it is then rotated by 180° along the X-axis shown in Figure 13(a), resulting in an Euler angle rotation transformation of (90°, 90°, 15°); combining Figures 13(b) and (c), it is then rotated by 180° along the Z-axis of the new coordinate system shown in Figure 13(b), resulting in an Euler angle rotation transformation of (90°, 90°, 195°). Correspondingly, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are (90°, 90°, 195°).

[0156] With (α, β, γ) = (180°, 180°, 0°), referring to Figures 14(a) and (b), the crystal orientation of the piezoelectric material of the first piezoelectric layer 201 is first rotated 180° along the Z-axis shown in Figure 14(a), and the Euler angles are transformed to (90°, -90°, 165°); referring to Figures 14(b) and (c), it is then rotated 180° along the X-axis of the new coordinate system shown in Figure 14(b), and the Euler angles are transformed to (90°, 90°, 195°); as shown in Figure 14(c), it is then rotated 0° along the Z-axis of the new coordinate system shown in Figure 14(c). Correspondingly, the Euler angles of the piezoelectric material of the second piezoelectric layer 202 are (90°, 90°, 195°).

[0157] Optionally, the Euler angles of the piezoelectric material in the first piezoelectric layer 201 can also be (90°, 90°, 195°), and correspondingly, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are (90°, -90°, -15°). Alternatively, the Euler angles of the piezoelectric material in the first piezoelectric layer 201 can also be (90°, 90°, 180°), and correspondingly, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are (90°, 90°, 0°). Alternatively, the Euler angles of the piezoelectric material in the first piezoelectric layer 201 can also be (0°, 90°, 180°), and correspondingly, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are (0°, -90°, 0°).

[0158] Optionally, the Euler angles of the piezoelectric material in the first piezoelectric layer 201 can also be (90°, 270°, 180°), and correspondingly, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are (90°, 90°, 0°). Alternatively, the Euler angles of the piezoelectric material in the first piezoelectric layer 201 can also be (90°, 90°, 68.867°), and correspondingly, the Euler angles of the piezoelectric material in the second piezoelectric layer 202 are (90°, 90°, 0°).

[0159] It is understandable that the piezoelectric tensor components corresponding to the main resonant mode and the parasitic modes of the resonator will change accordingly with the rotation of the Euler angles of the piezoelectric material of the piezoelectric layer. Specifically, for the resonator 300 including the first piezoelectric layer 201 and the second piezoelectric layer 202, after the Euler angles of the piezoelectric materials of the first piezoelectric layer 201 and the second piezoelectric layer 202 are set according to the above rotation transformation relationship, the piezoelectric tensor components of the corresponding main resonant modes of the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same, and the piezoelectric tensor components of the corresponding parasitic modes are opposite.

[0160] Based on the above matrix A and piezoelectric tensor components e pqrThe calculation formula for ' is obtained by setting multiple piezoelectric layers 20 and adjusting only the polarity of the piezoelectric tensor components of the corresponding parasitic modes of the first piezoelectric layer 201 and the second piezoelectric layer 202: e 11 ' = e 111 ' = e 111 A 11 A 11 A 11 =-e 111 =-e 11 e 31 ' = e 311 ' = e 311 A 33 A 11 A 11 =-e 311 =-e 31 e 34 ' = e 332 ' = e 332 A 33 A 33 A 22 =e 332 =e 34 e 35 ' = e 331 ' = e 331 A 33 A 33 A 11 =-e 331 =-e 35 ;

[0161] Then we have:

[0162] Therefore, the Euler angles of the piezoelectric materials in the first piezoelectric layer 201 and the second piezoelectric layer 202 can have a rotational transformation relationship (α, β, γ) = (0°, 180°, 180°) or (180°, 180°, 0°), such that the piezoelectric tensor components corresponding to the principal resonant modes in the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same, while the piezoelectric tensor components corresponding to the parasitic modes are opposite. Even with a certain error in the above rotational transformation relationship, the piezoelectric tensor components corresponding to the principal resonant modes in the first piezoelectric layer 201 and the second piezoelectric layer 202 are approximately the same, while the piezoelectric tensor components corresponding to the parasitic modes have opposite signs and approximately the same absolute values.

[0163] This approach ensures that the main resonant mode of the resonator 300 remains unchanged or essentially unchanged, maintaining a large electromechanical coupling coefficient while significantly reducing the impact of thickness variations in each piezoelectric layer 20. Furthermore, it allows the parasitic modes corresponding to the first piezoelectric layer 201 and the parasitic modes corresponding to the second piezoelectric layer 202 to cancel each other out, effectively suppressing or even eliminating parasitic modes and improving the performance of the resonator 300.

[0164] In addition, by adopting the above-mentioned configuration, the difficulty of obtaining the first piezoelectric layer 201 and the second piezoelectric layer 202 can be reduced, the fabrication complexity of the resonator 300 can be reduced, and the cost can be reduced.

[0165] In some embodiments, the piezoelectric material of the first piezoelectric layer 201 and the piezoelectric material of the second piezoelectric layer 202 are the same.

[0166] This simplifies the fabrication of the resonator 300 and effectively ensures that the piezoelectric tensor components of the corresponding main resonant modes of the first piezoelectric layer 201 and the second piezoelectric layer 202 are the same, while the piezoelectric tensor components of the corresponding parasitic modes are opposite, so as to effectively suppress parasitic modes while ensuring the main resonant modes.

[0167] For example, the piezoelectric material of either the first piezoelectric layer 201 or the second piezoelectric layer 202 includes at least one combination of niobium and lithium, tantalum and lithium, or niobium and tantalum and lithium. Optionally, the material of either the first piezoelectric layer 201 or the second piezoelectric layer 202 includes at least one combination of lithium tantalate (LiTaO3) and lithium niobate (LiNbO3). For example, both the first piezoelectric layer 201 and the second piezoelectric layer 202 are made of lithium niobate.

[0168] In some embodiments, the thickness of the first piezoelectric layer 201 is H1, and the thickness of the second piezoelectric layer 202 is H2. As shown in FIG9, the thickness H1 of the first piezoelectric layer 201 may be greater than the thickness H2 of the second piezoelectric layer 202; or, as shown in FIG10, the thickness H1 of the first piezoelectric layer 201 may be less than the thickness H2 of the second piezoelectric layer 202; or, as shown in FIG11a, the thickness H1 of the first piezoelectric layer 201 may be equal to the thickness H2 of the second piezoelectric layer 202.

[0169] In some examples, 20%H2 ≤ H1 ≤ 500%H2. Alternatively, 20%H2 ≤ H1 ≤ 450%H2, 30%H2 ≤ H1 ≤ 450%H2, 30%H2 ≤ H1 ≤ 300%H2, 100%H2 ≤ H1 ≤ 300%H2, 150%H2 ≤ H1 ≤ 350%H2, etc. For example, H1 can be 20%, 50%, 80%, 110%, 160%, 200%, 250%, 300%, 400%, or 500% of H2, etc.

[0170] This approach avoids significantly increasing the thickness of the resonator 300 while effectively suppressing parasitic modes while ensuring the main resonant mode.

[0171] Figures 15, 16, 17 and 18 also illustrate a partial structure of a resonator.

[0172] In some embodiments, as shown in Figures 15 to 18, a gap exists between two adjacent second electrodes 30. A groove G is formed in one of the plurality of piezoelectric layers 20 at a position opposite to the gap. The groove G extends along the thickness direction of the first electrode and communicates with the gap.

[0173] For example, the orthographic projection of the second electrode 30 onto the first electrode 10 does not overlap with the orthographic projection of the trench G onto the first electrode 10. The second electrode 30 does not cover the trench G. Optionally, a portion of the boundary of the orthographic projection of the second electrode 30 onto the first electrode 10 coincides with a portion of the boundary of the orthographic projection of the adjacent trench G onto the first electrode 10.

[0174] By creating the trench G, the confinement of the piezoelectric layer 20 can be reduced, which not only helps to increase the electromechanical coupling coefficient Kt of the resonator. 2 It also helps to suppress parasitic modes.

[0175] In some examples, the trench G penetrates at least a portion of at least one piezoelectric layer 20. Exemplarily, the trench G may penetrate a portion or the entirety of a piezoelectric layer 20 closest to the second electrode 30; or, the trench G may penetrate the entirety of a piezoelectric layer 20 closest to the second electrode 30, and further extend into the portion of the piezoelectric layer 20 between the piezoelectric layer 20 and the first electrode 10.

[0176] Optionally, as shown in Figure 15, the trench G penetrates a portion of the second piezoelectric layer 202.

[0177] Alternatively, as shown in Figure 16, the trench G penetrates the entirety of the second piezoelectric layer 202.

[0178] Alternatively, as shown in Figure 17, the trench G penetrates the entire second piezoelectric layer 202 and a portion of the first piezoelectric layer 201.

[0179] Alternatively, as shown in Figure 18, the trench G penetrates the entirety of the second piezoelectric layer 202 and the entirety of the first piezoelectric layer 201. Correspondingly, the second piezoelectric layer 202 has a top surface away from the first piezoelectric layer 201, and the first piezoelectric layer 201 has a bottom surface away from the second piezoelectric layer 202, with the trench G penetrating both the top and bottom surfaces. The trench G also exposes the surface of the first electrode 10.

[0180] By adjusting the depth of the trench G (the dimension of the trench G in the thickness direction of the first electrode), the electromechanical coupling coefficient Kt of the resonator can be improved. 2 .

[0181] In some instances, as shown in Figures 16 and 17, the trench G has a groove angle θ, which can be understood as the angle between the side of the trench G and the reference plane, which is the side surface of the first electrode 10 near the second electrode 30.

[0182] For example, θ ≤ 90°. Optionally, 55° ≤ θ ≤ 80°. For example, the tilt angle θ can be 90°, 80°, 73°, 60°, or 55°, etc. As shown in Figure 18, when the tilt angle is 90° and the trench G penetrates the first piezoelectric layer 201 and the second piezoelectric layer 202, the orthographic projections of the first piezoelectric layer 201 and the second piezoelectric layer 202 on the first electrode 10 coincide. The portions of the first piezoelectric layer 201 and the second piezoelectric layer 202 located below the same second electrode 30 have the same size in the arrangement direction of the second electrode 30. The structures of the first piezoelectric layer 201 and the second piezoelectric layer 202 are relatively symmetrical, which makes the resonance of the first piezoelectric layer 201 and the second piezoelectric layer 202 more symmetrical.

[0183] Figure 19 also illustrates a top view of a plurality of second electrodes. Referring to Figures 19 and 18, along the arrangement direction of the plurality of second electrodes 30, the plurality of second electrodes 30 includes alternately arranged first interdigital electrodes 301 and second interdigital electrodes 302. That is, in each pair of adjacent second electrodes 30, one is a first interdigital electrode 301 and the other is a second interdigital electrode 302, and the first interdigital electrodes 301 and second interdigital electrodes 302 are spaced apart. Further, along the arrangement direction of the plurality of second electrodes 30, a second interdigital electrode 302 is disposed between each pair of adjacent first interdigital electrodes 301, and a first interdigital electrode 301 is disposed between each pair of adjacent second interdigital electrodes 302.

[0184] Referring again to Figure 19, the resonator further includes a first busbar 303 and a second busbar 304, which are disposed on the side of the plurality of piezoelectric layers 20 away from the first electrode 10. The first busbar 303 and the second busbar 304 are, for example, made of the same material as the plurality of second electrodes 30 and disposed in the same layer.

[0185] For example, along the extending direction of the second electrode 30, the first busbar 303 and the second busbar 304 are respectively located on opposite sides of the plurality of second electrodes 30, and both the first busbar 303 and the second busbar 304 extend along the arrangement direction of the plurality of second electrodes 30. The plurality of first interdigital electrodes 301 of the plurality of second electrodes 30 are connected by the first busbar 303, and the plurality of second interdigital electrodes 302 of the plurality of second electrodes 30 are connected by the second busbar 304.

[0186] The first busbar 303 can be used as an input terminal, and the second busbar 304 can be used as an output terminal. For example, an alternating voltage of a certain frequency range can be input to multiple first interdigital electrodes 301 through the first busbar 303, and an alternating voltage signal processed by a resonator can be output to multiple second interdigital electrodes 302 through the second busbar 304.

[0187] In some examples, as shown in Figure 19, the width dimension of each first interdigital electrode 301 is s1, the spacing between adjacent first interdigital electrodes 301 and second interdigital electrodes 302 is s2, and the pitch P is the sum of the width dimension s1 and the spacing s2. The width dimension s1 is the dimension of the first interdigital electrode 301 in the direction parallel to the first electrode 10 and perpendicular to the extension direction of the first interdigital electrode 301. For example, the width dimension of the first interdigital electrode 301 is equal to the width dimension of the second interdigital electrode 302. Here, the width dimension s1 of each first interdigital electrode 401 is allowed to have process tolerances, and the spacing s2 between adjacent first interdigital electrodes 301 and second interdigital electrodes 302 is also allowed to have process tolerances.

[0188] Furthermore, the finger spacing P and the thickness H of the piezoelectric layer 20 satisfy the condition: P / H ≥ 0.5. For example, the finger spacing P and the thickness H of any one of the piezoelectric layers 20 satisfy the condition: P / H ≥ 0.5. Optionally, the ratio of the finger spacing P to the thickness H of the piezoelectric layer 20 can be: 0.5, 1, 5, 10, 15, 20, 30, etc.

[0189] This allows the resonator to have a larger electromechanical coupling coefficient.

[0190] The following comparison, using the admittance curves shown in Figures 20 to 25, will illustrate the parasitic mode suppression of the resonator 300 comprising a double piezoelectric layer (i.e., the aforementioned first piezoelectric layer 201 and second piezoelectric layer 202) and the resonator comprising a single piezoelectric layer. The material of the piezoelectric layer in the different resonators is, for example, LN.

[0191] In the admittance simulation curves shown in Figure 20, the solid curve represents the admittance simulation curve of a resonator using a single piezoelectric layer, and the dashed curve represents the admittance simulation curve of a resonator using a double piezoelectric layer. The crystal cutting angle of the piezoelectric material in the piezoelectric layers of both resonators is X-cut. Due to modeling reasons, the vibration displacement distribution diagram in Figure 20 (same scale) does not explicitly show the double piezoelectric layer. Specifically, the structure of the resonator using a double piezoelectric layer (i.e., the first piezoelectric layer and the second piezoelectric layer) is, for example, the structure shown in Figure 16, and the physical parameters are shown in Table 1; the structure of the resonator using a single piezoelectric layer is similar to the structure shown in Figure 16, except that it only includes one piezoelectric layer.

[0192] Table 1

[0193] As shown in Figure 20, the main resonant mode of the resonator is the SH1 mode generated in direction 2, while the parasitic modes include the S0 mode and A1 mode generated in direction 1. Comparing the solid and dashed curves in Figure 20, with the double piezoelectric layer and the Euler angle rotation relationship of the piezoelectric material in the double piezoelectric layer being (0°, 180°, 180°) or (180°, 180°, 0°), the main resonant mode SH1 of the resonator remains basically unchanged, and the parasitic modes (i.e., the S0 mode and A1 mode) are effectively suppressed.

[0194] Furthermore, as can be seen from the vibration displacement distribution diagram in Figure 20, for the leftmost row of resonators, the S0 mode vibration amplitude is relatively large in the resonators including single-layer piezoelectric layers, while the S0 mode vibration amplitude is significantly reduced in the resonators including double-layer piezoelectric layers. This means that the S0 mode has been effectively suppressed. For the middle row of resonators, the vibration amplitude of the SH1 mode in the resonators including single-layer piezoelectric layers is basically the same as that in the resonators including double-layer piezoelectric layers, which means that the SH1 mode remains basically unchanged and is not adversely affected. For the rightmost row of resonators, the A1 mode vibration amplitude is relatively large in the resonators including single-layer piezoelectric layers, while the A1 mode vibration amplitude is significantly reduced in the resonators including double-layer piezoelectric layers. This also means that the A1 mode has been effectively suppressed.

[0195] Furthermore, calculations can be performed to obtain the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer. 34 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 34 The values ​​are the same, and both are -4.2258C / m. 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 11 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 11 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 11 -4.138C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 11 It is 4.138C / m 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 It is 1.4909 C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 -1.4909C / m 2In other words, the main resonant mode SH1 of the resonator including the multilayer piezoelectric layer provided in this application embodiment remains basically unchanged, and parasitic modes (i.e., S0 mode and A1 mode) can be effectively suppressed.

[0196] Furthermore, it can be seen from region B enclosed by the dashed ellipse in Figure 20 that the dashed curve is located below the solid curve. Compared with resonators including a single piezoelectric layer, the SV leakage of the resonator including a multi-layer piezoelectric layer provided in the embodiments of this application is significantly reduced.

[0197] In the admittance simulation curves shown in Figure 21, the solid curve represents the admittance simulation curve of a resonator using a single piezoelectric layer, and the dashed curve represents the admittance simulation curve of a resonator using a double piezoelectric layer. The crystal cutting angle of the piezoelectric material in the piezoelectric layers of both resonators is X-cut. Due to modeling reasons, the vibration displacement distribution diagram in Figure 21 (same scale) does not explicitly show the double piezoelectric layer. Specifically, the structure of the resonator using a double piezoelectric layer (i.e., the first piezoelectric layer and the second piezoelectric layer) is, for example, the structure shown in Figure 18, and the physical parameters are shown in Table 2; the structure of the resonator using a single piezoelectric layer is similar to the structure shown in Figure 18, except that it only includes one piezoelectric layer.

[0198] Table 2

[0199] As shown in Figure 21, the main resonant mode of the resonator is the SH1 mode generated in direction 2, while the parasitic modes include the S0 mode and A1 mode generated in direction 1. Comparing the solid and dashed curves in Figure 21, with the double piezoelectric layer and the Euler angle rotation relationship of the piezoelectric material in the double piezoelectric layer being (0°, 180°, 180°) or (180°, 180°, 0°), the main resonant mode SH1 of the resonator remains basically unchanged, and the parasitic modes (i.e., the A1 mode) are effectively suppressed.

[0200] Furthermore, as can be seen from the vibration displacement distribution diagram in Figure 21, for the leftmost row of resonators, the vibration amplitude of the S0 mode in the resonators including a single piezoelectric layer is relatively similar to that in the resonators including a double piezoelectric layer, meaning that the S0 mode remains essentially unchanged. For the middle row of resonators, the vibration amplitude of the SH1 mode in the resonators including a single piezoelectric layer is essentially the same as that in the resonators including a double piezoelectric layer, meaning that the SH1 mode remains essentially unchanged and is not significantly affected. For the rightmost row of resonators, the vibration amplitude of the A1 mode is larger in the resonators including a single piezoelectric layer, while the vibration amplitude of the A1 mode is significantly reduced in the resonators including a double piezoelectric layer, meaning that the A1 mode is effectively suppressed.

[0201] Furthermore, calculations can be performed to obtain the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer. 34 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 34 The values ​​are the same, and both are -4.2258C / m. 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 It is 1.4909 C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 -1.4909C / m 2 In other words, the main resonant mode SH1 of the resonator including multiple piezoelectric layers provided in this application embodiment remains basically unchanged, and the parasitic mode A1 can be effectively suppressed.

[0202] Furthermore, it can be seen from region C enclosed by the dashed ellipse in Figure 21 that the dashed curve is located below the solid curve. Compared to resonators including a single piezoelectric layer, the SV leakage (due to the piezoelectric tensor component e) of the resonator including a multi-layer piezoelectric layer provided in this application embodiment is significantly lower than that of a resonator including a single piezoelectric layer. 35 (Causes) a significant reduction.

[0203] In the admittance simulation curves shown in Figure 22, the solid curve represents the admittance simulation curve of a resonator using a single piezoelectric layer, and the dashed curve represents the admittance simulation curve of a resonator using a double piezoelectric layer. The crystal cutting angle of the piezoelectric material in the piezoelectric layers of both resonators is Y-cut. Due to modeling reasons, the vibration displacement distribution diagram in Figure 22 (same scale) does not explicitly show the double piezoelectric layer. Specifically, the structure of the resonator using a double piezoelectric layer (i.e., the first piezoelectric layer and the second piezoelectric layer) is, for example, the structure shown in Figure 17, and the physical parameters are shown in Table 3; the structure of the resonator using a single piezoelectric layer is similar to the structure shown in Figure 17, except that it only includes one piezoelectric layer.

[0204] Table 3

[0205] As shown in Figure 22, the main resonant mode of the resonator is the SH1 mode generated in direction 2, and the parasitic modes include the S0 mode generated in direction 1. Comparing the solid and dashed curves in Figure 22, with the double piezoelectric layer and the Euler angle rotation relationship of the piezoelectric material in the double piezoelectric layer being (0°, 180°, 180°) or (180°, 180°, 0°), the main resonant mode SH1 of the resonator remains basically unchanged, and the parasitic modes (i.e., the S0 mode) are effectively suppressed.

[0206] Furthermore, as can be seen from the vibration displacement distribution diagram in Figure 22, for the leftmost row of resonators, the vibration amplitude of the SH1 mode in the resonators including the single-layer piezoelectric layer is basically no different from that in the resonators including the double-layer piezoelectric layer. This means that the SH1 mode remains essentially unchanged and is not adversely affected. For the rightmost row of resonators, the vibration amplitude of the S0 mode is larger in the resonators including the single-layer piezoelectric layer, while the vibration amplitude of the S0 mode is significantly reduced in the resonators including the double-layer piezoelectric layer. This means that the S0 mode is effectively suppressed.

[0207] Furthermore, calculations can be performed to obtain the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer. 34 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 34 The values ​​are the same, and both are -3.6959C / m. 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 31 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 31 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 31 It is 2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 31 -2.5338C / m 2 In other words, the main resonant mode SH1 of the resonator including the multilayer piezoelectric layer provided in this application embodiment remains basically unchanged, and the parasitic mode S0 can be effectively suppressed.

[0208] As can be seen from the above, the resonator with multilayer piezoelectric layers provided in this application is applicable not only to YBARs with X-cut piezoelectric materials, but also to YBARs with Y-cut piezoelectric materials.

[0209] In the admittance simulation curves shown in Figure 23, the solid curve represents the admittance simulation curve of a resonator using a single piezoelectric layer, and the dashed curve represents the admittance simulation curve of a resonator using a double piezoelectric layer. The crystal cutting angle of the piezoelectric material in the piezoelectric layers of both resonators is X-cut. Due to modeling reasons, the vibration displacement distribution diagram in Figure 23 (same scale) does not explicitly show the double piezoelectric layer. Specifically, the structure of the resonator using a double piezoelectric layer (i.e., the first piezoelectric layer and the second piezoelectric layer) is, for example, the structure shown in Figure 10, and the physical parameters are shown in Table 4; the structure of the resonator using a single piezoelectric layer is similar to the structure shown in Figure 10, except that it only includes one piezoelectric layer.

[0210] Table 4

[0211] As shown in Figure 23, the main resonant mode of the resonator is the SH1 mode generated in direction 2, while the parasitic modes include the S0 mode and A1 mode generated in direction 1. Comparing the solid and dashed curves in Figure 23, with the double piezoelectric layer and the Euler angle rotation relationship of the piezoelectric material in the double piezoelectric layer being (0°, 180°, 180°) or (180°, 180°, 0°), the main resonant mode SH1 of the resonator remains basically unchanged, and the parasitic modes (i.e., the S0 mode and A1 mode) are effectively suppressed.

[0212] Furthermore, as can be seen from the vibration displacement distribution diagram in Figure 23, for the leftmost row of resonators, the S0 mode vibration amplitude is relatively large in the resonators including single-layer piezoelectric layers, while the S0 mode vibration amplitude is significantly reduced in the resonators including double-layer piezoelectric layers. This means that the S0 mode has been effectively suppressed. For the middle row of resonators, the vibration amplitude of the SH1 mode in the resonators including single-layer piezoelectric layers is basically the same as that in the resonators including double-layer piezoelectric layers, which means that the SH1 mode remains basically unchanged and is not adversely affected. For the rightmost row of resonators, the A1 mode vibration amplitude is relatively large in the resonators including single-layer piezoelectric layers, while the A1 mode vibration amplitude is significantly reduced in the resonators including double-layer piezoelectric layers. This also means that the A1 mode has been effectively suppressed.

[0213] Furthermore, calculations can be performed to obtain the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer. 34 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 34 The values ​​are the same, and both are -3.6959C / m. 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 11 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 11 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 11 -2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 11 It is 2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 It is 2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 -2.5338C / m 2In other words, the main resonant mode SH1 of the resonator including the multilayer piezoelectric layer provided in this application embodiment remains basically unchanged, and parasitic modes (i.e., S0 mode and A1 mode) can be effectively suppressed.

[0214] It is understandable that by setting trenches, the longitudinal propagation of the S0 mode in direction 1 can be suppressed or blocked. As can be seen from Figures 10 and 23, in this embodiment, by setting multiple piezoelectric layers and setting the Euler angle rotation relationship between adjacent piezoelectric materials to (0°, 180°, 180°) or (180°, 180°, 0°), parasitic modes can be effectively suppressed without setting trenches. This reduces the need for trenches, or even eliminates the need for them, thereby avoiding the increased complexity of the manufacturing process and potential structural parameter differences caused by etching trenches.

[0215] In the admittance simulation curves shown in Figure 24, the solid curve represents the admittance simulation curve of a resonator using a single-layer piezoelectric layer, and the dashed curve represents the admittance simulation curve of a resonator using a double-layer piezoelectric layer. The crystal cutting angle of the piezoelectric material in the piezoelectric layers of both resonators is X-cut. Due to modeling reasons, the vibration displacement distribution diagram in Figure 24 (same scale) does not explicitly show the double-layer piezoelectric layer. Specifically, the structure of the resonator using a double-layer piezoelectric layer (i.e., the first piezoelectric layer and the second piezoelectric layer) is, for example, the structure shown in Figure 9, and the physical parameters are shown in Table 5; the structure of the resonator using a single-layer piezoelectric layer is similar to the structure shown in Figure 9, except that it only includes one piezoelectric layer.

[0216] Table 5

[0217] As shown in Figure 24, the main resonant mode of the resonator is the SH1 mode generated in direction 2, and the parasitic modes include the third-order SV mode generated in direction 3. Comparing the solid and dashed curves in Figure 24, with the double piezoelectric layer and the Euler angle rotation relationship of the piezoelectric material in the double piezoelectric layer being (0°, 180°, 180°) or (180°, 180°, 0°), the main resonant mode SH1 of the resonator remains basically unchanged, and the parasitic modes (i.e., the third-order SV mode) are effectively suppressed.

[0218] Furthermore, as can be seen from the vibration displacement distribution diagram in Figure 24, for the leftmost row of resonators, the vibration amplitude of the SH1 mode in the resonators including the single-layer piezoelectric layer is basically no different from that in the resonators including the double-layer piezoelectric layer. This means that the SH1 mode remains essentially unchanged and is not adversely affected. For the rightmost row of resonators, the vibration amplitude of the third-order SV mode is larger in the resonators including the single-layer piezoelectric layer, while the vibration amplitude of the third-order SV mode is significantly reduced in the resonators including the double-layer piezoelectric layer. This means that the third-order SV mode is effectively suppressed.

[0219] Furthermore, calculations can be performed to obtain the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer. 34 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 34 The values ​​are the same, and both are -3.6959C / m. 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 -2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 It is 2.5338C / m 2 In other words, the main resonant mode SH1 of the resonator including the multilayer piezoelectric layer provided in this application embodiment remains basically unchanged, and the parasitic mode S0 can be effectively suppressed.

[0220] In the admittance simulation curves shown in Figure 25, curve 1 represents the admittance simulation curve of the resonator using a single-layer piezoelectric layer, curve 2 represents the admittance simulation curve of the resonator using a double-layer piezoelectric layer in Example 1, and curve 3 represents the admittance simulation curve of the resonator using a double-layer piezoelectric layer in Example 2. The crystal cutting angle of the piezoelectric material of the piezoelectric layer in the three resonators is X-cut. Due to modeling reasons, the vibration displacement distribution diagram in Figure 25 (same scale) does not explicitly show the double-layer piezoelectric layer. Specifically, the structure of the resonator using a double-layer piezoelectric layer (i.e., the first piezoelectric layer and the second piezoelectric layer) is, for example, the structure shown in Figure 9, and the physical parameters are shown in Table 6; the structure of the resonator using a single-layer piezoelectric layer is similar to the structure shown in Figure 9, except that it only includes one piezoelectric layer.

[0221] Table 6

[0222] As shown in Figure 25, the main resonant mode of the resonator is the SH1 mode generated in direction 2, and the parasitic modes include the SH0 mode generated in direction 2 and the A1 mode generated in direction 1. Comparing curves 1 and 2 in Figure 25, after transforming the Euler angles of the piezoelectric materials of the upper and lower piezoelectric layers according to a certain rotational transformation relationship, the main resonant mode SH1 of the resonator remains basically unchanged, and the A1 mode in the parasitic modes is effectively suppressed. Comparing curves 1 and 3 in Figure 25, after transforming the Euler angles of the piezoelectric materials of the upper and lower piezoelectric layers according to a certain rotational transformation relationship, the main resonant mode SH1 of the resonator remains basically unchanged, the A1 mode in the parasitic modes is effectively suppressed, and the SH0 mode in the parasitic modes is suppressed to a certain extent.

[0223] Furthermore, as can be seen from the vibration displacement distribution diagram in Figure 25, for the leftmost row of resonators, including the resonators with a single piezoelectric layer, the vibration amplitude of the SH1 mode is basically no different from that of the resonators in Embodiment 1 and Embodiment 2. This means that the SH1 mode remains essentially unchanged and is not adversely affected. For the middle row of resonators, the vibration amplitude of the SH0 mode in the resonators with a single piezoelectric layer is relatively large. The vibration amplitude of the SH0 mode in the resonators in Embodiment 1 is basically unchanged, while the vibration amplitude of the SH0 mode in the resonators in Embodiment 2 is somewhat reduced. For the rightmost row of resonators, the vibration amplitude of the A1 mode in the resonators with a single piezoelectric layer is relatively large. The vibration amplitude of the A1 mode in the resonators in Embodiment 1 and Embodiment 2 is significantly reduced, which means that the A1 mode is effectively suppressed.

[0224] Furthermore, calculations show that in Examples 1 and 2, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer is... 34 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 34 The values ​​are the same, and both are 3.6959 C / m. 2 .

[0225] In Example 1, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 It is 2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 -2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 16 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 16 The values ​​are the same, and both are 3.6959 C / m. 2 .

[0226] In Example 2, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 Conversely, the piezoelectric tensor component e of the piezoelectric material of the first piezoelectric layer 35 It is 2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 -2.5338C / m 2 The piezoelectric tensor component e of the piezoelectric material in the first piezoelectric layer 16 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 16 The piezoelectric tensor components e of the piezoelectric material in the first piezoelectric layer are different. 16 -0.94357C / m 2 The piezoelectric tensor component e of the piezoelectric material of the second piezoelectric layer 35 It is 3.6959 C / m 2 .

[0227] In other words, the main resonant mode SH1 of the resonator including the multilayer piezoelectric layer provided in the embodiments of this application remains basically unchanged; the parasitic mode A1 in Embodiment 1 can be effectively suppressed; the parasitic mode SH0 in Embodiment 2 can be suppressed to a certain extent, and the parasitic mode A1 can be effectively suppressed.

[0228] As can be seen from the above, the resonator with multilayer piezoelectric layers provided in this application embodiment is applicable not only to solid substrate YBARs, but also to suspended thin film YBARs.

[0229] In Tables 1 to 5 above, the percentage ratio can be understood as the ratio between the width of a second electrode and the spacing between the fingers.

[0230] In Tables 1 to 4 above, the second electrode is, for example, composed of stacked aluminum and titanium films. In Tables 1, 2, and 3, the thickness of the aluminum film in the second electrode is 85 nm, and the thickness of the titanium film is 5 nm. In Table 4, the thickness of the aluminum film in the second electrode is 120 nm, and the thickness of the titanium film is 5 nm. In Tables 5 and 6 above, the second electrode is, for example, composed of an aluminum film.

[0231] In some possible embodiments, for a resonator including a piezoelectric layer, by adjusting a series of structural parameters in the resonator (e.g., the duty cycle of the second electrode), the parasitic A1 mode generated near the main resonant mode resonance point and the main resonant mode anti-resonant point can be effectively suppressed. Figure 26 shows the admittance simulation curve obtained with a duty cycle of 0.6, and Figure 27 shows the admittance simulation curve obtained with a duty cycle of 0.37.

[0232] While adjusting the resonator's structural parameters can effectively suppress parasitic modes, these parameters can fluctuate to varying degrees across batches, wafers, and within wafers due to different manufacturing processes. This can lead to unstable suppression of parasitic modes, ultimately causing passband glitches or out-of-band suppression glitches in the filter, affecting filter performance and reducing device production yield.

[0233] The embodiments of this application, by setting multiple piezoelectric layers and defining the rotational transformation relationship of the Euler angles of the piezoelectric materials of adjacent piezoelectric layers as (0°, 180°, 180°) or (180°, 180°, 0°), can effectively suppress parasitic modes while ensuring that the main resonant mode remains essentially unchanged. This avoids adjustments to structural parameters, eliminating reliance on the control of resonator structural parameters (such as finger spacing, fill power ratio, groove depth, etc.), thereby reducing the sensitivity of the strength of parasitic mode suppression to changes in actual manufacturing processes, which is very beneficial for subsequent processing steps.

[0234] Solid-state piezoelectric thin-film resonators, such as those mentioned above, or suspended thin-film piezoelectric thin-film resonators, can be used as sensors, such as temperature, humidity, and pressure sensors. Alternatively, they can be used as delay line devices in various high-frequency signal processing applications ranging from 100MHz to 30GHz.

[0235] The aforementioned suspended thin-film piezoelectric thin-film resonators, or solid-substrate piezoelectric thin-film resonators, can be electrically connected in a trapezoidal structure as shown in Figure 28 to realize filters for radio frequency communication. The filter can contain resonators connected in series or in parallel. The resonant frequency of the parallel resonators can be lower than that of the series resonators. For example, a thicker piezoelectric layer 20 or a larger finger spacing in the aforementioned resonator fabrication structure can reduce the resonant frequency.

[0236] The structure shown in Figure 28 includes resonators 301, 302, 303, 304, and 305. Resonators 301, 302, and 303 are series resonators, while resonators 304 and 305 are parallel resonators. At least one of the resonators 301 to 305 can be the resonator 300 comprising multiple piezoelectric layers 20 as described in the above embodiments.

[0237] In some examples, as shown in Figure 29, which illustrates the relationship between the admittance curves of the individual resonators in the trapezoidal filter of Figure 28 and the transmission loss curve of the filter. As shown in Figure 29, the resonant points of the series resonators (such as resonators 301, 302, and 303) and the anti-resonant points of the parallel resonators (such as resonators 304 and 305) are located within the passband, forming the filter's passband. The anti-resonant points of the series resonators (such as resonators 301, 302, and 303) are located at the high-frequency side outside the passband, while the resonant points of the parallel resonators (such as resonators 304 and 305) are located at the low-frequency side outside the passband. This results in a filter with high roll-off and high out-of-band rejection.

[0238] The filters described in this application embodiment can also be applied to duplexers or multiplexers. In a duplexer, a transmit channel filter and a receive channel filter are included, at least one of which can be filtered using the filter described above. In a multiplexer, multiple transmit channel filters and multiple receive channel filters are included, wherein at least one of the multiple transmit channel filters, or at least one of the multiple receive channel filters, can be the filter described in this application embodiment.

[0239] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0240] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed herein should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A resonator, characterized by, The resonator includes: First electrode; Multiple piezoelectric layers are stacked on the first electrode; A plurality of second electrodes are disposed on the side of the plurality of piezoelectric layers away from the first electrode, and are spaced apart on the side of the plurality of piezoelectric layers away from the first electrode; The plurality of piezoelectric layers include an adjacent first piezoelectric layer and a second piezoelectric layer, wherein the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer and the second piezoelectric layer are different in magnitude.

2. The resonator of claim 1, wherein The parasitic modal piezoelectric tensor components include at least one or more of: e 11 , e 16 , e 31 , and e 35 .

3. The resonator according to claim 1 or 2, characterized in that The parasitic mode piezoelectric tensor components of the piezoelectric materials of the first and second piezoelectric layers have opposite signs.

4. The resonator according to any one of claims 1-3, characterized in that, The absolute values ​​of the parasitic mode piezoelectric tensor components of the piezoelectric materials of the first piezoelectric layer and the second piezoelectric layer are the same.

5. The resonator according to any one of claims 1 to 4, characterized in that, the first piezoelectric layer and the second piezoelectric layer have the same sign of a main resonance mode piezoelectric tensor component of the piezoelectric material of the first piezoelectric layer and the second piezoelectric layer, the main resonance mode piezoelectric tensor component comprising at least e 34 .

6. The resonator of claim 5, wherein The piezoelectric tensor components of the principal resonant modes of the piezoelectric materials of the first and second piezoelectric layers have the same magnitude.

7. The resonator according to any one of claims 1 to 6, characterized in that, The Euler angles of the piezoelectric material in the first piezoelectric layer are (α1, β1, γ1), and the Euler angles of the piezoelectric material in the second piezoelectric layer are (α2, β2, γ2); the rotational transformation relationship between the Euler angles of the piezoelectric material in the first piezoelectric layer and the Euler angles of the piezoelectric material in the second piezoelectric layer is (α, β, γ). (α, β, γ) = (0°±10°, 180°±10°, θ±10°), or (α, β, γ) = (0°±10°, 0°±10°, θ±10°), or (α, β, γ) = (180°±10°, 180°±10°, θ±10°), where θ is any angle between 0° and 360°.

8. The resonator of claim 7, wherein The values ​​of θ include 0°, 68.867°, 180° or 320°.

9. The resonator according to claim 7 or 8, characterized in that There is a gap between two adjacent second electrodes; A groove is formed at a position opposite to the gap in the plurality of piezoelectric layers. The groove extends along the thickness direction of the first electrode and communicates with the gap.

10. The resonator of claim 9, wherein, The trench penetrates at least a portion of at least one of the piezoelectric layers.

11. The resonator according to claim 9 or 10, characterized in that The first piezoelectric layer is located between the second piezoelectric layer and the first electrode; The second piezoelectric layer has a top surface away from the first piezoelectric layer, and the first piezoelectric layer has a bottom surface away from the second piezoelectric layer, with the trench penetrating the top surface and the bottom surface.

12. The resonator of any one of claims 1 to 11, wherein, The piezoelectric material of the first piezoelectric layer is the same as that of the second piezoelectric layer.

13. The resonator of claim 12, wherein, The piezoelectric material of either the first piezoelectric layer or the second piezoelectric layer includes at least one combination of niobium and lithium, tantalum and lithium, or niobium and tantalum and lithium.

14. The resonator of any one of claims 1 to 13, wherein, The thickness of the first piezoelectric layer is H1, and the thickness of the second piezoelectric layer is H2, wherein 20%H2≤H1≤500%H2.

15. The resonator of any one of claims 1 to 14, wherein, The crystal cutting angle of the piezoelectric materials in the first and second piezoelectric layers is X-cut; α1=90°, β1=90°, γ1=195°; α2=90°, β2=-90°, γ2=-15°; or, α1=90°, β1=90°, γ1=180°; α2=90°, β2=-90°, γ2=0°; or, α1=90°, β1=270°, γ1=180°; α2=90°, β2=90°, γ2=0°; or, α1=90°, β1=90°, γ1=68.867°; α2=90°, β2=90°, γ2=0°.

16. The resonator of any one of claims 1 to 15, wherein, The crystal cutting angle of the piezoelectric materials in the first and second piezoelectric layers is Y-cut; α1=0°, β1=90°, γ1=180°; α2=0°, β2=-90°, γ2=0°.

17. The resonator of any one of claims 1 to 16, wherein, The resonator also includes a substrate located on the side of the first electrode away from the plurality of piezoelectric layers.

18. The resonator of claim 17, wherein, The substrate material includes at least one of silicon carbide, boron nitride, and diamond.

19. The resonator of any one of claims 1 to 18, wherein, The resonator further includes: a first busbar and a second busbar; the first busbar and the second busbar are disposed on the side of the plurality of piezoelectric layers away from the first electrode; Along the arrangement direction of the plurality of second electrodes, the plurality of second electrodes include alternately arranged first interdigital electrodes and second interdigital electrodes; The plurality of first interdigital electrodes in the plurality of second electrodes are connected through the first busbar, and the plurality of second interdigital electrodes in the plurality of second electrodes are connected through the second busbar; The spacing P between the finger strips and the thickness H of the piezoelectric layer satisfy: P / H≥0.5; The width dimension of the first interdigital electrode is s1, the distance between adjacent first interdigital electrodes and second interdigital electrodes is s2, the finger spacing P = s1 + s2, and the width dimension is a dimension parallel to the first electrode and perpendicular to the extension direction of the first interdigital electrode.

20. A filter, characterized by The filter includes: a plurality of resonators electrically connected; At least one of the resonators is a resonator as described in any one of claims 1 to 19.

21. An electronic device, comprising: The electronic device includes: The resonator as described in any one of claims 1 to 19, or the filter as described in claim 20; An amplifier is electrically connected to either the resonator or the filter.

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