Filter and electronic device

Abstract

The present application relates to the technical field of resonators. Provided in the embodiments are a filter and an electronic device. The filter comprises: a substrate; and a first resonator and a second resonator which are arranged on the substrate; the first resonator comprises a first region of the substrate and a first piezoelectric layer provided in the first region of the substrate, a plurality of first electrodes being provided on the first piezoelectric layer side by side in a first direction; the second resonator comprises a second region of the substrate and a second piezoelectric layer provided in the second region of the substrate, a plurality of second electrodes being provided on the second piezoelectric layer side by side in a second direction, and the difference between the first direction and the second direction being 70°-110°. In the embodiments of the present application, the first resonator and the second resonator can work in different working modes, so that additional manufacturing procedures for forming the first resonator and the second resonator of the filter can be reduced.

Description

Filter and electronic device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 30, 2023, with application number 202311641241.X and application name “A Filter and Electronic Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of resonator technology, and in particular to a filter and an electronic device. Background Art

[0003] A filter is a device that achieves passband and out-of-band transmission characteristics by creating a certain frequency difference between a series resonator and a parallel resonator. Therefore, under the same manufacturing and structural conditions, the resonator should have good performance when used as a series resonator and a parallel resonator.

[0004] Summary of the Invention

[0005] Embodiments of the present application provide a filter and an electronic device, which are used to ensure that both the series resonator and the parallel resonator in the filter have good performance.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, a filter is provided, comprising: a substrate; a first resonator and a second resonator on the substrate; wherein the first resonator comprises a first region of the substrate, and a first piezoelectric layer disposed on the first region of the substrate, and a plurality of first electrodes are arranged side by side along a first direction on the first piezoelectric layer; the second resonator comprises a second region of the substrate, and a second piezoelectric layer disposed on the second region of the substrate; a plurality of second electrodes are arranged side by side along a second direction on the second piezoelectric layer; and the first direction and the second direction differ by 70°-110°.

[0008] The filter provided in this embodiment forms a first resonator and a second resonator on the same substrate. The propagation directions of the multiple first electrodes in the first resonator and the multiple second electrodes in the second resonator differ by 70°-110°. Therefore, the first resonator and the second resonator can operate in different operating modes, for example, the first resonator operates in a first-order horizontal shear mode, and the second resonator operates in a first-order antisymmetric mode. This reduces the additional manufacturing steps required to form the first and second resonators. For example, there is no need to use different piezoelectric layer thicknesses for the first and second resonators, ensuring substrate uniformity and thickness consistency, thereby improving the filter's on-chip performance uniformity, manufacturability, and reliability.

[0009] In some possible implementations, the first piezoelectric layer includes a first piezoelectric material, and the Euler angle of the crystal of the first piezoelectric material is (90°, 90°, 30°±30°), or the crystal cutting angle and propagation direction of the first piezoelectric material are X-cut and (30°±30°)Y direction, wherein the X direction of the first piezoelectric material is in the same direction as the thickness direction of the first piezoelectric layer, and the (30°±30°)Y direction of the first piezoelectric material is in the same direction as the first direction; the second piezoelectric layer includes a second piezoelectric material, and the Euler angle of the crystal of the second piezoelectric material is (90°, 90°, 120°±30°), or the crystal cutting angle and propagation direction of the second piezoelectric material are X-cut and (120°±30°)Y direction, wherein the X direction of the second piezoelectric material is in the same direction as the thickness direction of the second piezoelectric layer, and the (120°±30°)Y direction of the second piezoelectric material is in the same direction as the second direction.

[0010] In this implementation, the first resonator uses an X-cut, 30°±30°Y propagation direction, and the Euler angles of the crystal of the first piezoelectric material are (90°, 90°, 30°±30°), obtaining the maximum K 34 2 Thus, the first-order horizontal shear mode SH1 of the first resonator will be excited as the main resonant mode. The second resonator 320 uses X-cut, 120°±30°Y propagation direction, and the Euler angles of the second piezoelectric material crystal are (90°, 90°, 120°±30°), obtaining the maximum K 35 2 , so that the first-order antisymmetric mode A1 of the second resonator will be excited as the main resonant mode. Because the resonant modes of the first and second resonators are different, the acoustic velocities of the first and second piezoelectric layers are also different, and thus the frequencies of the first and second resonators are also different. While maintaining the performance of the filter, it is possible to reduce the additional manufacturing process of the first and second resonators when forming the filter, ensure the uniformity and thickness consistency of the substrate, and thus improve the on-chip performance uniformity, manufacturability, and reliability of the filter.

[0011] In some possible implementations, the first piezoelectric layer includes a first piezoelectric material, and the Euler angle of the crystal of the first piezoelectric material is (0°, 90°, 0°±30°), or the crystal cutting angle and propagation direction of the first piezoelectric material are Y-cut and (0°±30°)X direction, wherein the Y-cut of the first piezoelectric material is in the same direction as the thickness direction of the first piezoelectric layer, and the (0°±30°)X direction is in the same direction as the first direction; the second piezoelectric layer includes a second piezoelectric material, and the Euler angle of the crystal of the second piezoelectric material is (0°, 90°, 90°±30°), or the crystal cutting angle and propagation direction of the second piezoelectric material are Y-cut and (90°±30°)X direction, wherein the Y direction of the second piezoelectric material is in the same direction as the thickness direction of the second piezoelectric layer, and the (90°±30°)X direction of the second piezoelectric material is in the same direction as the second direction.

[0012] In this implementation, the first resonator uses a Y-cut, 0°±30°X propagation direction, and the Euler angles of the crystal of the first piezoelectric material are (0°, 90°, 0°±30°), obtaining the maximum K 34 2 Thus, the first-order horizontal shear mode SH1 of the first resonator will be excited as the main resonant mode. The second resonator uses Y-cut, 90°±30°X propagation direction, and the Euler angles of the crystal of the second piezoelectric material are (0°, 90°, 90°±30°), obtaining the maximum K 35 2 , so that the first-order antisymmetric mode A1 of the second resonator will be excited as the main resonant mode. Because the resonant modes of the first and second resonators are different, the acoustic velocities of the first and second piezoelectric layers are also different, and thus the frequencies of the first and second resonators are also different. While maintaining the performance of the filter, it is possible to reduce the additional manufacturing process of the first and second resonators when forming the filter, ensure the uniformity and thickness consistency of the substrate, and thus improve the on-chip performance uniformity, manufacturability, and reliability of the filter.

[0013] In some possible implementations, the first resonator further includes a third electrode disposed between the first region of the substrate and the first piezoelectric layer. This generates an electric field between the first electrode and the third electrode along the thickness of the first piezoelectric layer. The first piezoelectric layer utilizes this electric field to generate a piezoelectric effect, thereby converting electrical energy into mechanical energy.

[0014] In some possible implementations, the second resonator further includes a fourth electrode disposed between the second region of the substrate and the second piezoelectric layer. This allows an electric field to be generated between the second electrode and the fourth electrode along the thickness of the second piezoelectric layer. The second piezoelectric layer utilizes this electric field to create a piezoelectric effect, thereby converting electrical energy into mechanical energy. In some possible implementations, the thicknesses of the first piezoelectric layer and the second piezoelectric layer are equal. This reduces the number of additional manufacturing steps required to form the first and second resonators, ensures substrate uniformity, and thus improves filter reliability.

[0015] In some possible implementations, the first resonator further includes: a first bus bar and a second bus bar; one of every two adjacent first electrodes among the multiple first electrodes is a first interdigitated electrode, and the other is a second interdigitated electrode; the first interdigitated electrodes and the second interdigitated electrodes are spaced apart in the first direction; multiple first interdigitated electrodes among the multiple first electrodes are connected through the first bus bar, and multiple second interdigitated electrodes among the multiple first electrodes are connected through the second bus bar.

[0016] In this implementation, the first busbar can serve as an input terminal, and the second busbar can serve as an output terminal. For example, an alternating voltage within a certain frequency range can be input to the plurality of first interdigital electrodes via the first busbar, and the plurality of second interdigital electrodes can output an alternating voltage signal processed by the first resonator via the second busbar.

[0017] In some possible implementations, the second resonator further includes: a third bus bar and a fourth bus bar; one of every two adjacent second electrodes in the plurality of second electrodes is a third interdigitated electrode, and the other is a fourth interdigitated electrode; the third interdigitated electrode and the fourth interdigitated electrode are spaced apart in the second direction; the plurality of third interdigitated electrodes in the plurality of second electrodes are connected via the third bus bar, and the plurality of fourth interdigitated electrodes in the plurality of second electrodes are connected via the fourth bus bar.

[0018] In this implementation, the third bus bar can serve as an input terminal, and the fourth bus bar can serve as an output terminal. For example, an alternating voltage within a certain frequency range can be input to the plurality of third interdigital electrodes via the third bus bar, and the plurality of fourth interdigital electrodes can output an alternating voltage signal processed by the second resonator via the fourth bus bar.

[0019] In some possible implementations, the second finger pitch P2 is equal to the first finger pitch P1, wherein the width of each third interdigital electrode is s3, the spacing between each adjacent third and fourth interdigital electrodes is s4, and the second finger pitch P2 = s3 + s4. This prevents the parasitic resonant frequency generated by the first or second resonator from being close to the main resonant frequency, thereby affecting the in-band insertion loss performance and out-of-band rejection performance of the filter.

[0020] In some possible implementations, the first resonator further includes: a first dielectric layer, the first dielectric layer being disposed between the first region of the substrate and the third electrode. Thus, by disposing the first dielectric layer between the substrate and the third electrode, direct coupling between the first piezoelectric layer and the substrate is weakened, thereby increasing the electromechanical coupling coefficient of the first resonator.

[0021] In some possible implementations, the material of the first piezoelectric layer includes at least one of niobium, a combination of lithium and oxygen, and tantalum, a combination of lithium and oxygen.

[0022] In some possible implementations, the filter further includes a passivation layer, where the passivation layer covers the first resonator and the second resonator.

[0023] In this implementation, the passivation layer protects the first and second resonators from corrosion, scratches, oxidation, and other effects, thereby maintaining the performance of the device. Furthermore, the passivation layer can adjust the resonant frequencies of the first and second resonators by varying their thickness, as well as the electromechanical coupling coefficient and temperature coefficient of the resonators.

[0024] In some possible implementations, the third electrode has a first surface and a second surface relative to each other, the first surface is located on a side close to the first piezoelectric layer; a cavity is provided in the first area of ​​the substrate, at least a portion of the second surface of the third electrode is used to enclose the cavity, and at least a portion of the third electrode is arranged between the cavity and the first piezoelectric layer.

[0025] In some possible implementations, the first resonator further includes: a stacked first reflective layer and a second reflective layer; the first reflective layer and the second reflective layer are disposed between the first region of the substrate and the third electrode.

[0026] In some possible implementations, the third electrode has a first surface and a second surface that are opposite to each other, the first surface is located on a side close to the first piezoelectric layer, and the second surface of the third electrode is in contact with the first portion of the substrate.

[0027] In some possible implementations, the first finger spacing P1 satisfies: Wherein: Vs is the shear wave velocity of the substrate, f1 is the operating frequency of the first resonator; wherein, the width dimension of each first interdigital electrode is s1, the spacing between each two adjacent first interdigital electrodes and second interdigital electrodes is s2, and the first finger spacing P1 = s1 + s2.

[0028] In this implementation, the substrate is a high-acoustic-velocity substrate, and when the first finger pitch P1 satisfies: When the resonant energy is effectively suppressed from leaking to the substrate layer, the quality factor Q value and the electromechanical coupling coefficient of the first resonator can be improved.

[0029] In a second aspect, an electronic device is provided. The electronic device includes: a control circuit; and a filter, wherein the filter is electrically connected to the control circuit.

[0030] Among them, the technical effects brought about by any possible implementation method of the second aspect can refer to the technical effects brought about by the different implementation methods of the above-mentioned first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic diagram of a partial structure of an electronic device provided in an embodiment of the present application;

[0032] FIG2 is a schematic diagram of a partial structure of an electronic device provided in an embodiment of the present application;

[0033] FIG3 is a schematic diagram of a partial structure of a filter in an electronic device provided in an embodiment of the present application;

[0034] FIG4 is an admittance curve diagram of a resonator with passivation layers of different thicknesses provided in an embodiment of the present application;

[0035] FIG5 is a schematic diagram of a partial structure of a resonator provided in an embodiment of the present application;

[0036] FIG6 is an admittance curve diagram of the resonator shown in FIG5 ;

[0037] FIG7 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0038] FIG8 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0039] FIG9 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0040] FIG10 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0041] FIG11 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0042] FIG12 is an admittance curve diagram of a filter provided in an embodiment of the present application;

[0043] FIG13 is a dispersion curve diagram of a filter provided in an embodiment of the present application;

[0044] FIG14 is an admittance curve diagram of a filter provided in an embodiment of the present application;

[0045] FIG15 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0046] FIG16 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0047] FIG17 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0048] FIG18 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0049] FIG19 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0050] FIG20 is a schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0051] FIG21 is a schematic diagram of the admittance curves and filter bandpass of each resonator in FIG20;

[0052] FIG22 is a top view of a filter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] Before introducing the structure that can be implemented in the embodiments of the present application, the technical terms involved in the embodiments of the present application are first introduced.

[0054] Piezoelectric effect: This includes the direct piezoelectric effect and the inverse piezoelectric effect. The direct piezoelectric effect refers to the change in the electrical polarization of a piezoelectric material when subjected to a mechanical force, while the inverse piezoelectric effect refers to the deformation of the material when an external electric field is applied. The piezoelectric effect is primarily due to the anisotropy of the piezoelectric material's crystal structure and polarization.

[0055] Main resonant mode, parasitic spurious modes: The parasitic resonant frequency generated by a resonator may be close to the main resonant frequency. These spurious resonances may affect the main resonant mode, thereby affecting the filter's in-band insertion loss and out-of-band rejection performance. The parasitic resonances of a resonator are often referred to as spurious modes. When spurious modes fall near the main resonant mode, for example, near the resonance point or antiresonance point of the main resonant mode, they can affect the filter's in-band insertion loss and out-of-band rejection performance.

[0056] Piezoelectric coupling factor K t 2 : It is a key parameter of the resonator, the electromechanical coupling coefficient K t 2 It can reflect the conversion efficiency between mechanical energy and electrical energy, the electromechanical coupling coefficient K of the resonator t 2 Determines the relative frequency width between the resonant frequency and the anti-resonant frequency of the resonator. For example, when the resonator is used in filter design, this relative frequency width directly determines the bandwidth of the filter. It can be considered that the electromechanical coupling coefficient K t 2 The larger it is, the larger the bandwidth of the filter built through the ladder structure can be, and the better the performance.

[0057] Electromechanical coupling coefficient component k xy 2 :For single crystal piezoelectric materials, it has a fourth-order elastic tensor c, a third-order piezoelectric tensor e, and a second-order dielectric tensor ε. According to the right-hand rectangular coordinate system, it has the elastic tensor components c ijkl , piezoelectric tensor component e ijk , dielectric tensor component ε ij , where i,j,k,l={1,2,3}. Due to the symmetry of the single crystal structure, for example, c 1323 =c 3132 , we can simplify the component order and define {23,32}→4, {13,31}→5, {12,21}→6, for example, c 1323 =c 3132 →c 54 , 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 component, piezoelectric tensor component, and dielectric tensor component of the material, and the formula is:

[0058] Among them, x={1,2,3}, y={1,2,3,4,5,6}, ε xx S is the dielectric tensor component under fixed strain, c yy E is the elastic tensor component under fixed electric field strength.

[0059] The following explains the calculation methods and formulas of the elastic tensor components, piezoelectric tensor components, and dielectric tensor components at different crystal Euler angles.

[0060] For the piezoelectric material crystal orientation with Euler angle (0,0,0), taking LN as an example,

[0061] c E 11 =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 ;

[0062] 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 , unit is C / m 2 ; ε S 11 =43.6*ε0,ε S 33 =29.2*ε0,ε S 22 =ε S 11 , where ε0 is the dielectric constant of vacuum, 8.85*10 -12 F / m. The remaining components can be obtained by tensor symmetry, and the components without values ​​are zero. The components are simplified expressions. For the fourth-order elastic tensor component c E ijkl , the third-order piezoelectric tensor component e ijk , which can be expanded accordingly.

[0063] Now for the crystal orientation of piezoelectric materials with Euler angles (α, β, γ), the corresponding elastic tensor component c isE pqrs ', piezoelectric tensor component e pqr ', dielectric tensor component ε S pq ', can be calculated by the following formula:

[0064] c E pqrs '=c E ijkl A ip A jq A kr A ls ;

[0065] e pqr '=e ijk A ip A jq A kr ;

[0066] ε S pq '=ε S ij A ip A jq ;

[0067] The formula adopts the Einstein summation convention, where the 3*3 matrix A=(cosαcosγ-sinαcosβsinγ,-cosαsinγ-sinαcosβcosγ,sinαsinβ; sinαcosγ+cosαcosβsinγ,-sinαsinγ+cosαcosβcosγ,-cosαsinβ; sinβsinγ,sinβcosγ,cosβ).

[0068] Electromechanical coupling coefficient K t 2 and the electromechanical coupling coefficient component k xy 2 Relationship: electromechanical coupling coefficient K t 2 The electromechanical coupling coefficient component k xy 2 and the mode excited by the specific resonator structure. Generally speaking, the k corresponding to the main resonant mode of the resonator is xy 2 The larger the resonator's K t 2 For example, when lithium niobate (LN) is selected as the piezoelectric material, the maximum electromechanical coupling coefficient component k of LN is xy 2It can reach 0.9253. The resonator that uses this component to generate the main resonant mode has a larger overall electromechanical coupling performance, such as the electromechanical coupling coefficient K of the resonator. t 2 It can reach 25%. And, generally speaking, the electromechanical coupling coefficient component k corresponding to the main resonant mode xy 2 The larger the other electromechanical coupling coefficient components k xy 2 The smaller the , the larger the electromechanical coupling coefficient and the smaller the parasitic modes of the resonator.

[0069] Given a resonator structure, a resonant mode corresponds to an electromechanical coupling coefficient component k xy 2 , for example, the maximum electromechanical coupling coefficient component k of LN xy 2 Can include k 16 2 、k 15 2 、k 34 2 、k 35 2 , which excites these maximum electromechanical coupling coefficient components k xy 2 , the mode generated is the main resonant mode, and the modes generated by the other electromechanical coupling coefficient components can be mixed modes. For example, in XBAR, the maximum electromechanical coupling coefficient component k is excited 16 2 , generating the main resonant mode zero-order horizontal shear mode (Zero-order Shear Horizontal mode) SH0 mode; in YBAR, the maximum electromechanical coupling coefficient component k is excited 34 2 , generating the main resonant mode first-order horizontal shear mode (First-order Shear Horizontal mode) SH1 mode; in YBAR, the maximum electromechanical coupling coefficient component k is excited 35 2 , generating the main resonant mode first-order anti-symmetric mode (First-order Anti-symmetry mode) A1 mode.

[0070] Quality factor Q: represents the energy utilization rate of the device, that is, the ratio of the total energy received by the device to the energy dissipated in one vibration cycle. In the design of the filter, the electromechanical coupling coefficient K of the resonator constituting the filter is t 2 The quality factor Q value is an important parameter.

[0071] Euler angle of piezoelectric material: The Euler angle characterizes the relative rotation angle relationship between the original piezoelectric crystal structure in the X direction or Y direction, perpendicular to or parallel to the extension direction of the resonator fingers, respectively, in the wafer plane.

[0072] Admittance: In power electronics, admittance is defined as the reciprocal of impedance, symbolized by Y and measured in siemens (S). Like impedance, admittance is a complex number consisting of a real part (conductance G) and an imaginary part (susceptance B): Y = G + jB.

[0073] Admittance curve abs and admittance curve Re: Admittance curve abs(Y) = |Y|, which is the modulus (also known as amplitude) of Y and represents the overall response of the resonator. Re(Y) is the real part of Y, that is, the conductance G, which represents the loss of the resonator.

[0074] RaR range: The frequency range around the resonance frequency fr and the anti-resonance frequency fa. For example, the RaR range is (fr-(fa-fr) to (fa+(fa-fr)).

[0075] Electromechanical coupling R-aR: This represents the electromechanical coupling coefficient of a resonator based on the relative bandwidth between the resonant frequency fr and the antiresonant frequency fa. For example, the resonator's R-aR should be comparable to the target filter's relative bandwidth. Here, R-aR = (fa - fr) / ((fa + fr) / 2).

[0076] The present application provides an electronic device, including but not limited to products such as a radio frequency front end and a filter amplifier module, and may also include terminal devices such as mobile phones, tablet computers (pads), smart wearable products (e.g., smart watches, smart bracelets), virtual reality (VR) devices, augmented reality (AR) devices, drones, or other devices, or may also be base stations, televisions, routers, automobiles, and other devices. The present application does not impose any particular restrictions on the specific form of the electronic device.

[0077] In an electronic device such as the one described above, as shown in FIG1 , the electronic device 100 may include a control circuit 110 and a filter 200 . The control circuit 110 is connected to the filter 200 and is used to control the filter 200 to effectively filter out a specific frequency point in the signal or frequencies other than the frequency point, thereby obtaining a signal of a specific frequency or eliminating a signal of a specific frequency, so as to improve the working performance of the electronic device 100 .

[0078] FIG2 shows a partial circuit diagram of some electronic devices 100. As shown in FIG2 , 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 via a switch 900, respectively. Furthermore, the receiver 600 and the transmitter 700 are electrically connected to the baseband chip 800.

[0079] Receiver 600 shown in FIG2 includes filter 60a and filter 60c. A low-noise amplifier 60b is electrically connected between filter 60a and filter 60c. Filter 60c is electrically connected to buffer 60e via mixer 60d, and buffer 60e is electrically connected to voltage-controlled oscillator 60f. FIG2 is merely an exemplary receiver; electronic components may be added or reduced based on this circuit structure.

[0080] The transmitter 700 shown in FIG2 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, FIG2 is merely an exemplary transmitter, and electronic components may be added or reduced based on this circuit structure.

[0081] For example, in the transmitter 700 shown in FIG2 , the filter can effectively filter out a specific frequency point or frequencies other than the specific frequency point after the power amplifier amplifies the signal, or the filter can filter out noise signals of the low noise amplifier.

[0082] As shown in FIG3 , the filter 200 may include multiple resonators 300 a connected in series, or multiple resonators 300 b connected in parallel, or multiple resonators 300 a connected in series and resonators 300 b connected in parallel. It is understood that, hereinafter, resonators connected in parallel are referred to as parallel resonators, and resonators connected in series are referred to as series resonators.

[0083] In order to make the resonator have better performance when acting as a series resonator and a parallel resonator, in an optional example, the series resonator and the parallel resonator have different finger spacings, but the frequency gap between the series resonator and the parallel resonator cannot be covered by the different finger spacings. At the same time, the parasitic resonance frequency position generated by the resonator may be close to the main resonance frequency position. The parasitic resonance may affect the main resonance mode, thereby affecting the in-band insertion loss performance and out-of-band suppression performance of the filter.

[0084] In another optional example, the series resonator and the parallel resonator have different passivation layer thicknesses, but as the passivation layer thickness increases, the performance of the resonator also decreases. The admittance curve diagram shown in Figure 4 includes the modulus (abs) and real part (Re) of the admittance curve. Among them, (a) in Figure 4 shows the admittance curve diagram of the resonator when the passivation layer is not set. The electromechanical coupling coefficient K of the resonator is t 2 is 20.5%, and the electromechanical coupling R-aR is 9.5%. As the thickness of the passivation layer increases, FIG4 (ii) shows a schematic diagram of the admittance curve of the resonator when the passivation layer thickness is 25 nm. The electromechanical coupling coefficient K t 2 is 19.9%, and the electromechanical coupling R-aR is 9.5%; Figure 4 (iii) shows a schematic diagram of the admittance curve of the resonator when the passivation layer thickness is 50nm. The electromechanical coupling coefficient K t 2 is 15.4%, and the electromechanical coupling R-aR is 6.9%. When the thickness of the passivation layer is 120nm, the electromechanical coupling coefficient K t 2 is 7.1%, and the electromechanical coupling R-aR is 3.0%. It can be seen that with the increase of the thickness of the passivation layer, the electromechanical coupling coefficient K of the resonator t 2 The smaller it is, the smaller the bandwidth of the filter built by the ladder structure can be, and the performance of the filter will also be reduced.

[0085] In another optional example, the series resonator and the parallel resonator have different piezoelectric layer thicknesses, see the structural diagram of the filter shown in FIG5 and the admittance curve diagram shown in FIG6, wherein the admittance curve shown in FIG6 includes the modulus (abs) and real part (Re) of the admittance curve. FIG6 (a) is the admittance diagram of the series resonator, and FIG6 (b) is the admittance diagram of the parallel resonator. In this example, the piezoelectric layer thickness of the series resonator is 280nm, the finger pitch (Pitch) is 0.67um, and the electromechanical coupling coefficient K of the series resonator is 0.67um. t 2The electromechanical coupling coefficient K of the parallel resonator is 25.4%, the electromechanical coupling R-aR is 12.2%, the piezoelectric layer thickness of the parallel resonator is 380nm, the finger pitch (Pitch) is 0.64um, and the electromechanical coupling coefficient K of the parallel resonator is 25.4%. t 2 It is 23.9%, and the electromechanical coupling R-aR is 11.4%. It can be seen that the series resonator and the parallel resonator have good performance, but the thinning of the piezoelectric layer will reduce the quality factor of the series resonator, thereby reducing the reliability of the series resonator.

[0086] Therefore, under the same manufacturing and structural conditions, how to make the resonator have good performance when used as a series resonator and a parallel resonator is a very necessary technical solution. This will greatly help the actual manufacturing process to improve the filter performance and prevent the frequency or electromechanical coupling shift of the entire wafer scale, so as to facilitate the smooth progress of mass production.

[0087] To this end, an embodiment of the present application provides a filter. Referring to FIG7 , the filter includes a substrate 10; a first resonator 310 and a second resonator 320 disposed on the substrate 10; wherein the first resonator 310 includes a first region 101 of the substrate 10 and a first piezoelectric layer 201 disposed on the first region 101 of the substrate 10, with a plurality of first electrodes 401 arranged side by side along a first direction on the first piezoelectric layer 201; the second resonator 320 includes a second region 102 of the substrate 10 and a second piezoelectric layer 202 disposed on the second region 102 of the substrate 10; a plurality of second electrodes 402 arranged side by side along a second direction on the second piezoelectric layer 202; and the first direction and the second direction differ by 70°-110°.

[0088] In the filter illustrated in FIG7 , the first resonator includes a plurality of first electrodes 401 arranged along a first direction, and the second resonator includes a plurality of second electrodes 402 arranged along a second direction. The first and second directions differ by 70°-110°. The first direction can be understood as a direction perpendicular to or nearly perpendicular to the direction in which the second electrodes 402 extend. In one embodiment, the first direction is parallel to the direction in which the first piezoelectric layer 201 extends; in other words, the first direction is perpendicular to the stacking direction of the first piezoelectric layer 201 and the first electrodes 401.

[0089] In the filter provided in this embodiment, a first resonator 310 and a second resonator 320 are formed on the same substrate 10. The propagation directions of the multiple first electrodes 401 in the first resonator 310 and the multiple second electrodes 402 in the second resonator 320 differ by 70°-110°. Therefore, the first resonator 310 and the second resonator 320 can operate in different operating modes. For example, the first resonator 310 can be a parallel resonator, and the second resonator 320 can be a series resonator. This reduces the additional manufacturing steps for the parallel resonators and the series resonators. For example, it is not necessary to use different piezoelectric layer thicknesses for the parallel resonator and the series resonator, ensuring the uniformity of the substrate 10, thereby improving the reliability of the filter.

[0090] In an optional embodiment, referring to the portion of a process structure diagram of a filter shown in FIG8 , the filter includes a substrate 10; a first resonator 310 and a second resonator 320 disposed on the substrate 10; wherein the first resonator 310 includes a first region 101 of the substrate 10, and a third electrode 501 and a first piezoelectric layer 201 stacked on the first region 101 of the substrate 10, with a plurality of first electrodes 401 arranged side by side along a first direction on the first piezoelectric layer 201; the second resonator 320 includes a second region 102 of the substrate 10, and a fourth electrode 502 and a second piezoelectric layer 202 stacked on the second region 102 of the substrate 10; and a plurality of second electrodes 402 are arranged side by side along a second direction on the second piezoelectric layer 202.

[0091] The first resonator 310 and the second resonator 320 in the example structure of Figure 8 can be thin-film plate wave resonators. The main working principle of thin-film plate wave resonators is to utilize the piezoelectric effect characteristics of piezoelectric materials and use input and output transducers to convert the input signal of the radio wave into mechanical energy. After processing, the mechanical energy is converted into an electrical signal to achieve the goal of filtering out unnecessary signals and noise and improving the reception quality.

[0092] During operation, the first resonator 310 shown in FIG8 can be operated without an electrical signal connection to the third electrode 501. Instead, an alternating voltage of a certain frequency is applied to the first electrode 401, generating an electric field E between the first electrode 401 and the third electrode 501 along the thickness direction of the first piezoelectric layer 201. The first piezoelectric layer 201 utilizes this electric field to produce a piezoelectric effect. FIG8 illustrates the use of a vertical electric field E to excite the first piezoelectric layer 201 to produce resonance, thereby converting electrical energy into mechanical energy.

[0093] The first resonator 310 shown in FIG8 utilizes electric field excitation resonance along the thickness direction of the first piezoelectric layer 201. In one embodiment, it can be referred to as a vertically-excited bulk acoustic resonator (YBAR). The thickness direction of the first piezoelectric layer 201 can be understood as the direction parallel to the stacking direction of the multiple membrane layers (substrate 10, third electrode 501, first piezoelectric layer 201) on the first piezoelectric layer 201.

[0094] It is understandable that the working principle and working process of the second resonator 320 are similar to those of the first resonator 310 . For details, please refer to the above working principle and working process, which will not be described in detail in the embodiment of the present application.

[0095] In the filter of the embodiment of the present application, as shown in Figure 9, in some examples, the first piezoelectric layer 201 in this embodiment includes a first piezoelectric material, and the Euler angle of the crystal of the first piezoelectric material is (90°, 90°, 30°±30°); or, it can be understood that the crystal cutting angle and propagation direction of the first piezoelectric material are X-cut, (30°±30°) Y direction.

[0096] The "X" in the above-mentioned X-cut represents the X direction of the first piezoelectric material. The X-cut can be used to indicate that the X direction of the first piezoelectric material is in the same direction as the thickness direction of the first piezoelectric layer 201 (such as the Y1 direction in Figure 9). The propagation direction of the first resonator is parallel to the surface of the first piezoelectric layer 201 and perpendicular to the extension direction of the first electrode 401. In one embodiment, the Y direction of the first piezoelectric material (30°±30°) is in the same direction as the first direction.

[0097] In this embodiment, the second piezoelectric layer 202 includes a second piezoelectric material, and the Euler angle of the crystal of the second piezoelectric material is (90°, 90°, 120°±30°); alternatively, it can be understood that the crystal cutting angle and propagation direction of the second piezoelectric material are X-cut and (120°±30°)Y direction, wherein the X direction of the second piezoelectric material is in the same direction as the thickness direction of the second piezoelectric layer 202, and the Y direction of the second piezoelectric material (120°±30°) is in the same direction as the second direction.

[0098] The "X" in the above-mentioned X-cut represents the X direction of the second piezoelectric material. The X-cut can be used to indicate that the X direction of the second piezoelectric material is in the same direction as the thickness direction of the second piezoelectric layer 202 (such as the Y1 direction in Figure 9). The propagation direction of the second piezoelectric material is parallel to the surface of the second piezoelectric layer 202 and perpendicular to the extension direction of the second electrode 402. In one embodiment, the Y direction of the second piezoelectric material (120°±30°) is in the same direction as the second direction.

[0099] It is understood that the above-mentioned "same direction" positioning allows for a certain error and can be close to the same direction. In one embodiment, a difference of 5° (inclusive) between the two angles can be regarded as close to the same direction.

[0100] The Euler angles, cutting angles, or propagation directions involved in the embodiments of the present application, for example, the tangent angles of the first piezoelectric material and the second piezoelectric material are generally accurate to <±0.5°, such as: X-cut ±0.5°, Y-cut ±0.5°, etc. In Euler angle expression, these are (90°±0.5°, 90°±0.5°, 30°±30°) or (90°±0.5°, 90°±0.5°, 120°±30°).

[0101] For example, the Euler angles may be (89.5°, 90.5°, 0°), or the Euler angles may be (89.5°, 90.5°, 30°), or the Euler angles may be (89.5°, 90.5°, 90°), or the Euler angles may be (89.5°, 90°, 40°), or the Euler angles may be (90°, 90°, 10°).

[0102] For example, the Euler angles may be (90.5°, 89.5°, 90°), or the Euler angles may be (90°, 90.5°, 120°), or the Euler angles may be (90°, 90.5°, 110°), or the Euler angles may be (90.5°, 90.5°, 100°), or the Euler angles may be (90.5°, 90°, 115°).

[0103] In this embodiment, the first resonator 310 can use an X-cut, 30°±30°Y propagation direction, and the Euler angles of the crystal of the first piezoelectric material are (90°, 90°, 30°±30°), to obtain the maximum K 34 2 Thus, the first-order shear horizontal mode (SH1) of the first resonator 310 is excited as the main resonant mode. In the SH1 main resonant mode, the vibration direction is the direction z shown in FIG9 , that is, the vibration direction is parallel to the substrate surface and perpendicular to the first direction.

[0104] The second resonator 320 can use an X-cut, 120°±30° Y propagation direction, and the Euler angles of the second piezoelectric material crystal are (90°, 90°, 120°±30°), to obtain the maximum K 35 2, thus exciting the first-order anti-symmetry mode A1 of the second resonator 320 as the primary resonant mode. In the A1 primary resonant mode, the primary vibration direction is direction X1 as shown in FIG9 , which is parallel to the second direction. In some examples, the A1 primary resonant mode also drives vibration in direction Y1.

[0105] The direction X1, direction Y1 and direction Z1 involved in the embodiments of the present application are different from the X direction and Y direction in the first piezoelectric layer, and also different from the X direction and Y direction in the second piezoelectric layer. The direction X1 can be understood as being parallel to the substrate surface and parallel to the first direction, the direction Y1 is parallel to the thickness direction of the first piezoelectric layer 201, and the direction Z1 is parallel to the substrate surface and perpendicular to the first direction.

[0106] Since the resonant modes of the first resonator 310 and the second resonator 320 are different, the acoustic velocities of the first piezoelectric layer 201 and the second piezoelectric layer 202 are also different, and thus the frequencies of the first resonator and the second resonator are also different. This can ensure the performance of the filter while reducing the additional manufacturing procedures of the first resonator 310 and the second resonator 320 when forming the filter, ensuring the uniformity of the substrate, and thus improving the reliability of the filter.

[0107] In conjunction with Figures 10 and 11, Figure 11 shows a process structure diagram of a filter, and Figure 11 shows a distribution diagram of the first electrode 401 and the second electrode 402 in Figure 10. On the side of the first piezoelectric layer 201 in Figure 10 away from the third electrode 501, a plurality of first electrodes 401 are provided. The plurality of first electrodes 401 include a plurality of first interdigital electrodes 4011 and a plurality of first interdigital electrodes 4012. For example, along a direction perpendicular to the extending direction of the first interdigital electrodes 4011, the plurality of first interdigital electrodes 4011 and the plurality of first interdigital electrodes 4012 can be arranged side by side, and the plurality of first interdigital electrodes 4011 and the plurality of first interdigital electrodes 4012 can be arranged at intervals, that is, a first interdigital electrode 4012 can be provided between two adjacent first interdigital electrodes 4011. Alternatively, the first interdigital electrodes 4011 and the first interdigital electrodes 4012 are spaced apart in the first direction, and an extension direction of the first interdigital electrodes 4011 and / or the first interdigital electrodes 4012 is perpendicular to the first direction.

[0108] The plurality of first interdigital electrodes 4011 are connected via a first bus bar 403, and the plurality of first interdigital electrodes 4012 are connected via a second bus bar 404. For example, the first bus bar 403 and the second bus bar 404 are arranged in parallel, and both the first bus bar 403 and the second bus bar 404 extend in a direction perpendicular to the extending direction of the first interdigital electrodes 4011 or the first interdigital electrodes 4012. As shown in FIG. 11 , the first bus bar 403 and the second bus bar 404 extend in the 30° Y direction.

[0109] The first bus bar 403 can serve as an input terminal, and the second bus bar 404 can serve as an output terminal. For example, an alternating voltage within a certain frequency range can be input to the plurality of first interdigital electrodes 4011 via the first bus bar 403, and an alternating voltage signal processed by the first resonator 310 can be output to the plurality of first interdigital electrodes 4012 via the second bus bar 404.

[0110] In an optional example, the first finger spacing P1 satisfies: Where: Vs is the shear wave velocity of the substrate 10, f1 is the operating frequency of the first resonator 310, the width of each first interdigital electrode 4011 is s1, the spacing between each adjacent first interdigital electrode 4011 and first interdigital electrode 4012 is s2, and the first interdigital pitch (P1) is the sum of the width s1 and the spacing s2. This prevents energy leakage toward the substrate 10 and improves the Q value and electromechanical coupling coefficient of the first resonator 310.

[0111] In FIG11 , a plurality of second electrodes 402 are provided on a side of the second piezoelectric layer 202 away from the fourth electrode 502. The plurality of second electrodes 402 include a plurality of third interdigital electrodes 4021 and a plurality of fourth interdigital electrodes 4022. For example, the plurality of third interdigital electrodes 4021 and the plurality of fourth interdigital electrodes 4022 may be arranged side by side along a direction perpendicular to the extension direction of the third interdigital electrodes 4021. Alternatively, the plurality of third interdigital electrodes 4021 and the plurality of fourth interdigital electrodes 4022 may be arranged in an alternating pattern, that is, a fourth interdigital electrode 4022 may be provided between two adjacent third interdigital electrodes 4021. Alternatively, the third interdigital electrodes 4021 and the fourth interdigital electrodes 4022 may be spaced apart in the second direction, and the extension direction of the third interdigital electrodes 4021 and / or the fourth interdigital electrodes 4022 is perpendicular to the second direction.

[0112] The plurality of third interdigital electrodes 4021 are connected via a third bus bar 405, and the plurality of fourth interdigital electrodes 4022 are connected via a fourth bus bar 406. For example, the third bus bar 405 and the fourth bus bar 406 are arranged in parallel, and both extend in a direction perpendicular to the direction in which the third interdigital electrodes 4021 or the fourth interdigital electrodes 4022 extend. As shown in FIG11 , the third bus bar 405 and the fourth bus bar 406 extend along a 120° Y direction. Thus, the angle between the third bus bar 405 and the first bus bar 403 or between the third bus bar 405 and the second bus bar 404 is also 90°, and the angle between the fourth bus bar 406 and the first bus bar 403 or between the fourth bus bar 406 and the second bus bar 404 is also 90°.

[0113] The third bus bar 405 can serve as an input terminal, and the fourth bus bar 406 can serve as an output terminal. For example, an alternating voltage within a certain frequency range can be input to the plurality of third interdigital electrodes 4021 via the third bus bar 405, and an alternating voltage signal processed by the second resonator 320 can be output to the plurality of fourth interdigital electrodes 4022 via the fourth bus bar 406.

[0114] In an optional example, the second finger spacing P2 satisfies: Where: Vs is the shear wave velocity of the substrate 10, f2 is the operating frequency of the second resonator 320, each third interdigital electrode 4021 has a width of s3, the spacing between each adjacent third interdigital electrode 4021 and fourth interdigital electrode 4022 is s4, and the second interdigital pitch (P2) is the sum of the width s3 and the spacing s4. This prevents energy leakage toward the substrate 10 and improves the Q value and electromechanical coupling coefficient of the second resonator 320.

[0115] In order to prevent the parasitic resonant frequency position generated by the first resonator 310 or the second resonator 320 from being close to the main resonant frequency position, thereby affecting the in-band insertion loss performance and out-of-band suppression performance of the filter, in an optional example, the first finger spacing and the second finger spacing are approximately equal.

[0116] In one specific example, a difference of 10% (inclusive) between the first interdigital pitch P1 and the second interdigital pitch P2 can be considered approximately equal. It is understood that the width dimension s1 of the plurality of first interdigital electrodes 4011 is subject to process tolerance, as is the spacing s2 between two adjacent first interdigital electrodes 4011 and first interdigital electrodes 4012. Similarly, the width dimension s3 of the plurality of third interdigital electrodes 4021 is subject to process tolerance, as is the spacing s4 between two adjacent third interdigital electrodes 4021 and fourth interdigital electrodes 4022.

[0117] In a specific example, (1) in FIG. 12 is a simulation curve obtained by adopting the structural definition shown in Table 1, and (2) in FIG. 12 is a simulation curve obtained by adopting the structural definition shown in Table 2.

[0118] Table 1

[0119] Table 2

[0120] The thickness of the first piezoelectric layer 201 and the thickness of the first electrode 401 in Table 1 above refer to the height dimensions of the first piezoelectric layer 201 and the height dimensions of the first electrode 401 along the stacking direction of the multiple film layers (e.g., the Y1 direction in FIG. 10 ). The thickness of the second piezoelectric layer 202 and the thickness of the second electrode 402 in Table 2 above refer to the height dimensions of the second piezoelectric layer 202 and the height dimensions of the second electrode 402 along the stacking direction of the multiple film layers (e.g., the Y1 direction in FIG. 10 ).

[0121] The first duty ratio in Table 1 is the ratio of the width s1 of the first interdigital electrode to the first interdigital pitch P1, or the ratio of the width of the second interdigital electrode to the first interdigital pitch P1. In some examples, the width of the first interdigital electrode is equal to the width of the second interdigital electrode. The second duty ratio in Table 2 is the ratio of the width s3 of the third interdigital electrode to the second interdigital pitch P2, or the ratio of the width of the fourth interdigital electrode to the second interdigital pitch P2. In some examples, the width of the third interdigital electrode is equal to the width of the fourth interdigital electrode.

[0122] The electromechanical coupling coefficient K in Table 1 and Table 2 above t 2 The electromechanical coupling coefficient K can be used to characterize the electromechanical coupling performance of the first resonator 310 and the second resonator 320. t 2 The larger it is, the better the electromechanical coupling performance is.

[0123] In the admittance curve of the embodiment of the present application shown in Figure 12, the parasitic modes appearing near the resonance point of the SH1 main resonant mode are all outside the N79 frequency band and the 5G WIFI frequency band. Similarly, the parasitic modes appearing near the resonance point of the A1 main resonant mode are also all outside the N79 frequency band and the 5G WIFI frequency band. Therefore, the filter provided in the embodiment of the present application has good in-band insertion loss performance and out-of-band suppression performance.

[0124] In this embodiment, the first resonator 310 can use an X-cut, 30° Y propagation direction, and the Euler angles of the crystal of the first piezoelectric material are (90°, 90°, 30°), to obtain the maximum K 34 2Thus, the first-order horizontal shear mode SH1 of the first resonator 310 will be excited as the main resonant mode, and the second resonator 320 can use the X-cut, 120°Y propagation direction, and the Euler angles of the crystal of the second piezoelectric material are (90°, 90°, 120°), to obtain the maximum K 35 2 , thus the first-order anti-symmetry mode A1 of the second resonator 320 is excited as the main resonant mode. At the same time, because the resonant modes of the first and second resonators are different, the acoustic velocities of the first and second piezoelectric layers 201 and 202 are also different, resulting in different frequencies of the first and second resonators.

[0125] Exemplarily, the shear acoustic velocity Vt of the first piezoelectric layer 201 of the first resonator 310 is 4000 m / s. Therefore, the resonant frequency of the first resonator 310 is:

[0126] Wherein, Vt1 is the transverse shear velocity of the first piezoelectric layer, Vt2 is the longitudinal shear velocity of the first piezoelectric layer, and d LN is the thickness of the first piezoelectric layer 201.

[0127] The shear sound velocity Vt of the second piezoelectric layer 202 of the second resonator 320 is 4000 m / s, and the longitudinal wave sound velocity is 7000 m / s. Therefore, the resonant frequency of the second resonator 320 is:

[0128] Therefore, the first resonator 310 and the second resonator 320 in the filter provided in the embodiment of the present application can form a frequency difference between the first resonator 310 and the second resonator 320 by making the sound speed of the first piezoelectric layer 201 and the second piezoelectric layer 202 different while using the same geometric parameters. This can reduce the additional manufacturing process for forming the first resonator 310 and the second resonator 320 while ensuring the performance of the filter, ensure the uniformity of the substrate 10, and thus improve the reliability of the filter.

[0129] Exemplarily, the geometric parameters include the thickness of the first piezoelectric layer 201, the thickness of the second piezoelectric layer 202, the thickness of the first electrode 401, the thickness of the second electrode 402, the thickness of the third electrode 501, the thickness of the fourth electrode 502, the first finger spacing, the second finger spacing, the first duty cycle, the second duty cycle, etc. It will be appreciated that the frequency difference between the first resonator 310 and the second resonator 320 can be adjusted by adjusting the geometric parameters of the first resonator 310 and the second resonator 320.

[0130] Refer to the dispersion curves shown in Figure 13, wherein (1) in Figure 13 is the dispersion curve when both the first piezoelectric layer 201 and the second piezoelectric layer 202 use X-cut and 30°Y propagation direction, (2) in Figure 13 is the dispersion curve when both the first piezoelectric layer 201 and the second piezoelectric layer 202 use X-cut and 120°Y propagation direction, and (3) in Figure 13 is the dispersion curve when the first piezoelectric layer 201 uses X-cut and 30°Y propagation direction, and the second piezoelectric layer 202 uses X-cut and 120°Y propagation direction. As the first finger spacing and the second finger spacing change, the frequency difference between the first resonator 310 and the second resonator 320 also changes. The first finger spacing and the second finger spacing can be set according to the required frequency difference.

[0131] In other examples, the Euler angle of the crystal of the first piezoelectric material in the first piezoelectric layer 201 in this embodiment can also be (0°, 90°, 0°±30°), or, it can be understood that the crystal cutting angle and propagation direction of the first piezoelectric material are Y-cut and (0°±30°) X direction.

[0132] The "Y" in the above Y-cut represents the Y direction of the first piezoelectric material. The Y-cut can be used to indicate that the Y-cut of the first piezoelectric material is in the same direction as the thickness direction of the first piezoelectric layer (such as the Y1 direction in Figure 9), and the (0°±30°) X direction is in the same direction as the first direction.

[0133] The second piezoelectric layer 202 includes a second piezoelectric material, the crystal Euler angle of the second piezoelectric material is (0°, 90°, 90°±30°), or the crystal cutting angle and propagation direction of the second piezoelectric material are Y-cut and (90°±30°) X direction.

[0134] The "Y" in the above Y-cut represents the Y direction of the second piezoelectric material. The Y-cut can be used to indicate that the thickness direction of the second piezoelectric layer is in the same direction, and the X direction of the second piezoelectric material (90°±30°) is in the same direction as the second direction.

[0135] It is understood that the above-mentioned "same direction" positioning allows for a certain error and can be close to the same direction. In one embodiment, a difference of 5° (inclusive) between the two angles can be regarded as close to the same direction.

[0136] FIG14 shows the admittance curves when the finger spacing of the first resonator 310 and the second resonator 320 in the embodiment of the present application is 1.08-1.14 μm. When the finger spacing of the first resonator 310 and the second resonator 320 changes, the position of the corresponding main resonant mode resonance point also changes accordingly. In this embodiment, the first resonator 310 can use a Y-cut, 0°±30°X propagation direction, and the Euler angles of the crystal of the first piezoelectric material are (0°, 90°, 0°±30°), to obtain the maximum K 342 Thus, the first-order horizontal shear mode SH1 of the first resonator 310 will be excited as the main resonant mode, and the second resonator 320 can use the Y-cut, 90°±30°X propagation direction, and the Euler angles of the crystal of the second piezoelectric material are (0°, 90°, 90°±30°), to obtain the maximum K 35 2 , so that the first-order antisymmetric mode A1 of the second resonator 320 will be excited as the main resonant mode. t 2 is 23%, the electromechanical coupling coefficient K t 2 The electromechanical coupling coefficient K can be used to characterize the electromechanical coupling performance of the first resonator 310 and the second resonator 320. t 2 The larger it is, the better the electromechanical coupling performance is.

[0137] According to Figure 14, it can be seen that in this embodiment, the parasitic heterodynes appearing near the resonance point of the SH1 main resonant mode are all outside the N79 frequency band and the 5G WIFI frequency band. Similarly, the parasitic heterodynes appearing near the resonance point of the A1 main resonant mode are also outside the N79 frequency band and the 5G WIFI frequency band. Therefore, the filter provided in the embodiment of the present application has good in-band insertion loss performance and out-of-band suppression performance.

[0138] It is understandable that the aforementioned embodiments and the beneficial effects brought about therewith are also applicable to this embodiment, and therefore, the same parts will not be repeated.

[0139] In an optional embodiment, referring to the process structure diagrams of two different filter structures shown in Figures 15 and 16 , in Figure 15 , a cavity 105 is formed in both the first region 101 and the second region 102 of the substrate 10. Such first resonator 310 and second resonator 320 can be referred to as a cavity 105-type suspended piezoelectric thin film resonator. In Figure 16 , compared to Figure 15 , the first region 101 and second region 102 of the substrate 10 in Figure 16 are solid structures without the cavity 105. Furthermore, compared to Figure 15 , other layer structures can be stacked between the first electrode 401 and the first region 101 of the substrate 10 and between the second electrode 402 and the second region 102 of the substrate 10. For example, a first dielectric layer 601 or other functional layer structures can be stacked between the substrate 10 and the first electrode 401. Such first resonator 310 and second resonator 320 in Figure 16 can be referred to as a solid substrate 10 piezoelectric thin film resonator.

[0140] Alternatively, the structures shown in Figures 15 and 16 can be understood as follows: taking the first resonator 310 as an example, the first electrode 401 has a first surface and a second surface that are relative (can also be called facing away or opposite), and the first surface is closer to the first piezoelectric layer 201 than the second surface; in the cavity 105-type suspended piezoelectric thin film resonator of Figure 15, a cavity 105 is provided in the first region 101 of the substrate 10, at least a portion of the second surface of the first electrode 401 is used to enclose the cavity 105, and at least a portion of the first electrode 401 is disposed between the cavity 105 and the first piezoelectric layer 201; in the solid substrate 10 piezoelectric thin film resonator of Figure 16, the first electrode 401 is disposed between the first dielectric layer 601 and the first piezoelectric layer 201, and the second surface of the first electrode 401 is in contact with the first dielectric layer 601. For example, in FIG. 16 , if the first dielectric layer 601 is not provided, the first electrode 401 is provided between the substrate 10 and the first piezoelectric layer 201 , and the second surface of the first electrode 401 is in contact with the substrate 10 .

[0141] In the resonator provided in the above embodiment, the substrate 10 may be a high acoustic velocity substrate 10, for example, any one of silicon carbide (SiC), diamond, and boron nitride (BN), or a combination of multiple materials.

[0142] The material of the first piezoelectric layer 201 includes at least one of niobium, a combination of lithium and oxygen, and tantalum, a combination of lithium and oxygen. For example, the material of the first piezoelectric layer 201 includes any one of lithium tantalate (LiTaO3), lithium niobate (LiNbO3), aluminum nitride (AlN), zinc oxide (ZnO), or a combination of multiple thereof.

[0143] The first electrode 401 can be made of any possible conductive metal (including but not limited to Al, Cu, W, Mo, Ru, Pt, etc.), or a conductive metal with high acoustic impedance (including but not limited to W, Ru, Mo, Pt, etc.). These metals with high acoustic impedance help to increase the electromechanical coupling coefficient and improve the quality factor Q, thereby further improving the performance of the resonator.

[0144] The third electrode 501 can be made of any possible conductive metal (including but not limited to Al, Cu, W, Mo, Ru, Pt, etc.). The first electrode 401 and the third electrode 501 can be made of the same conductive metal or different conductive metals.

[0145] In order to increase the connection strength between the third electrode 501 and the first dielectric layer 601 , as shown in FIG. 17 , a conductive connection layer 60 a may be stacked between the first dielectric layer 601 and the third electrode 501 .

[0146] Alternatively, in some other examples, in order to increase the connection strength between the first piezoelectric layer 201 and the third electrode 501 , referring to FIG. 17 , a conductive connection layer 60 b may be stacked between the first piezoelectric layer 201 and the third electrode 501 .

[0147] The conductive connection layer 60a and the conductive connection layer 60b in FIG. 17 may be made of the same material or different materials. For example, any possible conductive metal (including but not limited to Ti, Cr, etc.) may be selected. In some examples, the bonding strength of the conductive connection layer may be selected from 10 MPa to 40 GPa. For example, it may be 1.5 GPa.

[0148] Figure 18 is a process structure diagram of another filter provided in an embodiment of the present application. In Figure 18, a Bragg reflection structure 701 is formed on the first region 101 of the substrate 10, a third electrode 501 is disposed on a side of the Bragg reflection structure 701 away from the substrate 10, a first piezoelectric layer 201 is stacked between the first electrode 401 and the third electrode 501, and conductive connection layers (60a, 60b) are stacked between the first piezoelectric layer 201 and the third electrode 501, and between the third electrode 501 and the Bragg reflection structure.

[0149] The Bragg reflection structure 701 comprises a multi-layer stack of alternating layers of high- and low-acoustic-impedance materials. High-acoustic-impedance materials include, but are not limited to, tungsten (W), hafnium oxide (HfO2), and molybdenum (Mo); low-acoustic-impedance materials include, but are not limited to, silicon oxide (SiO2). This alternating stack creates a Bragg reflection effect for downward-propagating sound waves, suppressing downward energy leakage and improving the resonator's Q factor and electromechanical coupling coefficient.

[0150] For example, the Bragg reflection structure 701 includes a stacked first reflection layer and a second reflection layer, wherein the thickness t1 of the first reflection layer satisfies: The thickness t2 of the second reflective layer satisfies: λ1 is the wavelength of the sound wave at the resonant frequency of the first resonator 310 in the first reflective layer material, and λ2 is the wavelength of the sound wave in the second reflective layer material.

[0151] In some examples, In other examples, In some other examples,

[0152] If the first reflective layer and the second reflective layer are divided into one group, in some examples, the Bragg reflection structure 701 may include three groups, or more groups, for example, ten groups.

[0153] It should be understood that the above examples are merely examples for better understanding the technical solutions of the embodiments of the present invention and are not intended to be the sole limitations of the embodiments of the present invention. A Bragg reflection structure 701 may also be provided in the second resonator 320. For relevant details, reference may be made to the first resonator 310 in the above embodiment, and this application will not elaborate further.

[0154] Figure 19 is a process structure diagram of another filter according to an embodiment of the present application. Compared to Figures 15 to 18 above, this embodiment also includes a passivation layer 702. The surfaces of the first resonator 310 and the second resonator 320 that are away from the substrate 10 can be covered by the passivation layer 702. The passivation layer 702 can protect the first and second resonators from potential corrosion, scratches, oxidation, etc.

[0155] The passivation layer 702 may be made of a dielectric material, such as silicon oxide, silicon nitride, etc.

[0156] In addition, the passivation layer 702 can also adjust the electromechanical coupling coefficient and temperature coefficient of frequency (TCF) between the first resonator 310 and the second resonator 320 to further optimize the filtering performance of the device. Furthermore, the frequency difference between the first resonator 310 and the second resonator 320 can be further adjusted by adjusting the thickness of the passivation layer 702.

[0157] Furthermore, the aforementioned cavity-type suspended piezoelectric thin film resonators or solid-state substrate piezoelectric thin film resonators can be electrically connected in a trapezoidal structure as shown in FIG20 to implement a filter for radio frequency communication. In the filter, there can be resonators connected in series or in parallel. In the aforementioned embodiment, the first resonator 310 can be a parallel resonator, and the second resonator 320 can be a series resonator. The resonant frequency of the parallel resonator can be lower than the resonant frequency of the series resonator. For example, a thicker piezoelectric layer or a thicker passivation layer or a larger finger pitch P in the aforementioned resonator process structure can reduce the resonant frequency of the resonator.

[0158] In the example of Figure 20, the filter includes a second resonator 301, a second resonator 302, a second resonator 303, a first resonator 304, and a first resonator 305. The second resonators 301, 302, and 303 are series resonators, while the first resonator 304 and the first resonator 305 are parallel resonators. At least one of the first and second resonators among the second resonators 301, 302, 303, 304, and 305 can be the first and second resonators described in the above embodiments.

[0159] In some examples, such as FIG21 , FIG21 shows the relationship between the admittance curves of each resonator of the ladder filter and the transmission loss curve of the filter in FIG20 . Referring to FIG21 , the resonance points of the series resonators (such as the second resonator 301 , the second resonator 302 , and the second resonator 303 ) and the anti-resonance points of the parallel resonators (such as the first resonator 304 and the first resonator 305 ) are located within the passband frequency band, forming the passband of the filter. The anti-resonance points of the series resonators (such as the second resonator 301 , the second resonator 302 , and the second resonator 303 ) are located on the high-frequency side outside the passband, and the resonance points of the parallel resonators (such as the first resonator 304 and the first resonator 305 ) are located on the low-frequency side outside the passband. As a result, the filter has the characteristics of high roll-off and high out-of-band suppression.

[0160] In a filter, in an achievable process structure, multiple resonators provided in the embodiments of the present application can be integrated on the same substrate 10. For example, as shown in FIG22 , a second resonator 301, a second resonator 302, and a second resonator 303 connected in series are integrated on the substrate 10. The second resonator 301 and the second resonator 302 are electrically connected via a conductive connection layer 130, and the second resonator 302 and the second resonator 303 are electrically connected via a conductive connection layer 140. It will be appreciated that the conductive connection layer 130 or the conductive connection layer 140 can have a variety of achievable structures.

[0161] The filters involved in the above-mentioned embodiments of the present application can also be used in a duplexer or a multiplexer. In a duplexer, a transmit channel filter and a receive channel filter are included, and at least one of the transmit channel filter and the receive channel filter can be filtered using the above-mentioned filter. 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 use the filter involved in the embodiments of the present application.

[0162] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0163] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A filter, characterized in that: include: substrate; a first resonator and a second resonator disposed on the substrate; in, The first resonator includes a first region of a substrate, and a first piezoelectric layer disposed on the first region of the substrate, wherein a plurality of first electrodes are arranged side by side along a first direction on the first piezoelectric layer; The second resonator includes a second region of a substrate, and a second piezoelectric layer disposed on the second region of the substrate; a plurality of second electrodes are arranged side by side along the second direction on the second piezoelectric layer; The first direction differs from the second direction by 70°-110°.

2. The filter according to claim 1, characterized in that The first piezoelectric layer includes a first piezoelectric material, the Euler angle of the crystal of the first piezoelectric material is (90°, 90°, 30°±30°), or the crystal cutting angle of the first piezoelectric material and the propagation direction of the first resonator are X-cut, (30°±30°)Y direction, wherein the X direction of the first piezoelectric material is in the same direction as the thickness direction of the first piezoelectric layer, and the Y direction of the first piezoelectric material (30°±30°) is in the same direction as the first direction; The second piezoelectric layer includes a second piezoelectric material, and the Euler angle of the crystal of the second piezoelectric material is (90°, 90°, 120°±30°), or, the crystal cutting angle of the second piezoelectric material and the propagation direction of the first resonator are X-cut and (120°±30°)Y direction, wherein the X-cut of the second piezoelectric material is in the same direction as the thickness direction of the second piezoelectric layer, and the Y direction of the second piezoelectric material (120°±30°) is in the same direction as the second direction.

3. The filter according to claim 1, characterized in that The first piezoelectric layer includes a first piezoelectric material, the Euler angle of the crystal of the first piezoelectric material is (0°, 90°, 0°±30°), or the crystal cutting angle and propagation direction of the first piezoelectric material are Y-cut and (0°±30°)X direction, wherein the Y-cut direction of the first piezoelectric material is in the same direction as the thickness direction of the first piezoelectric layer, and the (0°±30°)X direction of the first piezoelectric material is in the same direction as the first direction; The second piezoelectric layer includes a second piezoelectric material, the Euler angle of the crystal of the second piezoelectric material is (0°, 90°, 90°±30°), or the crystal cutting angle and propagation direction of the second piezoelectric material are Y-cut and (90°±30°)X direction, wherein the Y-cut of the second piezoelectric material is in the same direction as the thickness direction of the second piezoelectric layer, and the (90°±30°)X direction of the second piezoelectric material is in the same direction as the second direction.

4. The filter according to any one of claims 1 to 3, characterized in that: The first resonator further includes a third electrode disposed between the first region of the substrate and the first piezoelectric layer.

5. The filter according to any one of claims 1 to 4, characterized in that: The second resonator further includes a fourth electrode disposed between the second region of the substrate and the second piezoelectric layer.

6. The filter according to any one of claims 1 to 5, characterized in that: The first piezoelectric layer and the second piezoelectric layer have the same thickness.

7. The filter according to any one of claims 1 to 6, characterized in that: The first resonator further includes: a first bus bar and a second bus bar; One of every two adjacent first electrodes in the plurality of first electrodes is a first interdigitated electrode, and the other is a second interdigitated electrode; the first interdigitated electrode and the second interdigitated electrode are spaced apart in the first direction; A plurality of the first interdigital electrodes among the plurality of first electrodes are connected through the first bus bar, and a plurality of the second interdigital electrodes among the plurality of first electrodes are connected through the second bus bar.

8. The filter according to claim 7, characterized in that The second resonator further includes: a third bus bar and a fourth bus bar; One of every two adjacent second electrodes in the plurality of second electrodes is a third interdigital electrode, and the other is a fourth interdigital electrode; the third interdigital electrode and the fourth interdigital electrode are spaced apart in the second direction; The plurality of third interdigital electrodes among the plurality of second electrodes are connected via the third bus bar, and the plurality of fourth interdigital electrodes among the plurality of second electrodes are connected via the fourth bus bar.

9. The filter according to claim 8, characterized in that The third electrode has a first surface and a second surface that are opposite to each other. The first surface is located on a side close to the first piezoelectric layer, and the second surface of the third electrode is in contact with the first portion of the substrate.

10. The filter according to claim 9, characterized in that The first finger spacing P1 satisfies: Wherein: Vs is the shear wave velocity of the substrate, f1 is the operating frequency of the first resonator; The width of each of the first interdigital electrodes is s1, the spacing between each two adjacent first interdigital electrodes and the second interdigital electrodes is s2, and the first finger spacing P1 = s1 + s2.

11. The filter according to claim 10, characterized in that The second finger spacing P2 is approximately equal to the first finger spacing P1, The width of each of the third interdigital electrodes is s3, the spacing between each two adjacent third interdigital electrodes and the fourth interdigital electrodes is s4, and the second finger spacing P2 = s3 + s4.

12. The filter according to claim 4, characterized in that The third electrode has a first surface and a second surface opposite to each other, wherein the first surface is located at a side close to the first piezoelectric layer; A cavity is provided in the first region of the substrate, at least a portion of the second surface of the third electrode is used to surround the cavity, and at least a portion of the third electrode is disposed between the cavity and the first piezoelectric layer.

13. The filter according to claim 4, characterized in that The first resonator further comprises: A stacked first reflective layer and a second reflective layer; The first reflective layer and the second reflective layer are disposed between the first region of the substrate and the third electrode.

14. The filter according to claim 4, characterized in that The first resonator further includes a first dielectric layer disposed between the first region of the substrate and the third electrode.

15. The filter according to any one of claims 1 to 14, characterized in that: The material of the first piezoelectric layer includes at least one of a combination of niobium, lithium and oxygen, and a combination of tantalum, lithium and oxygen.

16. The filter according to any one of claims 1 to 15, characterized in that: The filter further includes a passivation layer covering the first resonator and the second resonator.

17. An electronic device, characterized in that: include: Control circuit; The filter according to any one of claims 1 to 16, wherein the filter is electrically connected to the control circuit.

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