Resonator, filter, and electronic device

Abstract

The invention provides a resonator, a filter and electronic equipment. Relates to the technical field of resonators. The resonator can improve the electromechanical coupling coefficient. The resonator can comprise a substrate, a first electrode, a piezoelectric transduction layer and a plurality of second electrodes, the first electrode, the piezoelectric transduction layer and the multiple second electrodes are arranged on the substrate, the piezoelectric transduction layer is provided with a first side and a second side, the multiple second electrodes are located on the first side and are arranged side by side in the first direction, the first electrode is located on the second side, the first side deviates from the substrate, and the second side faces the substrate; the piezoelectric transduction layer comprises a first piezoelectric layer and a second piezoelectric layer which are stacked; the first piezoelectric layer has a first piezoelectric tensor component e33, the second piezoelectric layer has a second piezoelectric tensor component e33, and the first piezoelectric tensor component e33 and the second piezoelectric tensor component e33 are opposite. By using the adjacent piezoelectric layers with opposite piezoelectric tensor components e33, the resonator can have large vibration so as to improve the electromechanical coupling coefficient.

Description

Technical Field

[0001] The present application relates to the technical field of resonators, and in particular to a resonator, a filter having a resonator, and an electronic device including the filter or the resonator. Background Art

[0002] With the development of communication technology, the amount of resonators required for electronic devices will increase significantly. For example, BAW resonators such as horizontally-excited Bulk Acoustic Resonator (XBAR), vertically-excited Bulk Acoustic Resonator (YBAR), and film bulk acoustic resonator (FBAR) have attracted widespread attention.

[0003] Among them, YBAR has greater coupling and more effective resonance modes and can be used in a larger passband bandwidth.

[0004] However, in the YBAR device, since the piezoelectric layer is attached to the substrate, the acoustic resonance vibration of the part of the piezoelectric layer close to the substrate is restricted, so that the improvement of the electromechanical coupling coefficient of the resonator is suppressed. Summary of the invention

[0005] The present application provides a resonator, a filter having the resonator, and an electronic device including the filter. The object is to provide a resonator that can improve the electromechanical coupling coefficient.

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

[0007] In one aspect, the present application provides a resonator. In one embodiment, the resonator may be an acoustic wave resonator, such as a YBAR.

[0008] The resonator comprises: a substrate, a first electrode, a piezoelectric transducer layer and a plurality of second electrodes; the first electrode, the piezoelectric transducer layer and the plurality of second electrodes are arranged on the substrate, the piezoelectric transducer layer has a first side and a second side, the plurality of second electrodes are located on the first side and arranged side by side in a first direction, the first electrode is located on the second side, the first side is away from the substrate, and the second side is toward the substrate; wherein the piezoelectric transducer layer comprises a first piezoelectric layer and a second piezoelectric layer which are stacked; the first piezoelectric layer has a first piezoelectric tensor component e 33 , the second piezoelectric layer has a second piezoelectric tensor component e 33 , the first piezoelectric tensor component e 33 and the second piezoelectric tensor component e 33On the contrary, the first piezoelectric tensor component e 33 and the second piezoelectric tensor component e 33 They are opposite numbers.

[0009] In the resonator provided in the present application, the piezoelectric transducer layer includes multiple layers, for example, a stacked first piezoelectric layer and a second piezoelectric layer, and the first piezoelectric tensor component e of the first piezoelectric layer is 33 and the second piezoelectric tensor component e of the second piezoelectric layer 33 On the contrary, under the action of the electric field, the deformation direction of the first piezoelectric layer is opposite to the deformation direction of the second piezoelectric layer. For example, along the stacking direction of the first piezoelectric layer and the second piezoelectric layer, when the first piezoelectric layer is stretched and the second piezoelectric layer is compressed, the vibration direction of the part of the first piezoelectric layer that is in contact with the second piezoelectric layer is toward the second piezoelectric layer, and the vibration direction of the part of the second piezoelectric layer that is in contact with the first piezoelectric layer is also toward the second piezoelectric layer. These two vibrations couple and resonate at the position where the first piezoelectric layer and the second piezoelectric layer are in contact, so that mechanical vibrations are also generated inside the entire piezoelectric transducer layer, thereby improving the electromechanical coupling coefficient of the entire resonator.

[0010] In one achievable manner, the first electrode includes a first surface and a second surface that are back to back, the second surface is closer to the substrate than the first surface, and the second surface of the first electrode is completely disposed on the substrate.

[0011] The resonator given in this example can be called a solid substrate resonator. A resonator with this structure can improve the heat dissipation capability and robustness of the device.

[0012] In one achievable manner, there is a gap between two adjacent second electrodes; a groove is provided at a position of the piezoelectric transducer layer opposite to the gap, and the groove is connected to the gap.

[0013] Since the grooves are formed in the piezoelectric transducer layer, the grooves are helpful to further increase the electromechanical coupling coefficient of the resonator and can also suppress or frequency-shift the parasitic mode.

[0014] In one achievable manner, the thickness dimension H of the piezoelectric transducer layer and the depth dimension h of the groove satisfy 30% H≤h≤H.

[0015] When the groove depth is small, the vibration of the portion of the piezoelectric transducer layer located at the first electrode and the second electrode is restricted.

[0016] In one achievable manner, the first piezoelectric layer is arranged closer to the substrate than the second piezoelectric layer; the second piezoelectric layer has a top surface away from the first piezoelectric layer, the first piezoelectric layer has a bottom surface away from the second piezoelectric layer, and the groove runs through the top surface and the bottom surface.

[0017] Since the grooves penetrate from the top surface to the bottom surface of the piezoelectric transducer layer, the electromechanical coupling coefficient can be further increased.

[0018] In one achievable manner, the radial dimension of the groove gradually increases from the top surface to the bottom surface.

[0019] For example, the inclination angle α of the side surface of the groove satisfies: 45°<α<90°; or, 60°<α<90°.

[0020] In one achievable manner, the thickness dimension of the second electrode is S1, the thickness dimension of the piezoelectric transducer layer is H, and S1 / H≤0.35.

[0021] In one achievable manner, the thickness dimension of the first electrode is S2, the thickness dimension of the piezoelectric transducer layer is H, and S2 / H≤0.35.

[0022] In some examples, in order to reduce the acoustic loss at the electrode, the thickness of the first electrode or the second electrode can be reduced, but when the thickness of the electrode becomes thinner, the power tolerance of the electrode will be reduced. In the example of the present application, the thickness of the piezoelectric transducer layer can be increased to reduce the thickness ratio of the electrode to the piezoelectric transducer layer, which will neither pose a challenge to the etching process nor reduce the power tolerance of the electrode.

[0023] In one achievable manner, the resonator further includes: a first bus bar and a second bus bar; one of each two adjacent second electrodes among the plurality of second 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 in a first direction; a plurality of first interdigitated electrodes among the plurality of second electrodes are connected by a first bus bar, and a plurality of second interdigitated electrodes among the plurality of second electrodes are connected by a second bus bar; the finger spacing P and the thickness dimension H of the piezoelectric transducer layer satisfy: P / H≥1; the width dimension of each first interdigitated electrode is t1, the spacing between each two adjacent first interdigitated electrodes and the second interdigitated electrode is t2, the finger spacing P=t1+t2, and the width dimension is a dimension parallel to the surface of the substrate and perpendicular to the extension direction of the first interdigitated electrode.

[0024] In order to increase the resonant frequency of the resonator, the finger spacing P can be reduced. However, a smaller finger spacing P will not only pose a challenge to the etching process, but also introduce parasitic noise modes. In the embodiment of the present application, since a multi-layer stacked piezoelectric layer is used, by limiting the ratio of the finger spacing to the piezoelectric layer thickness, not only will it not pose a challenge to the etching process, but it can also suppress parasitic noise modes.

[0025] In one achievable manner, the thickness dimension S1 of the first piezoelectric layer and the thickness dimension S2 of the second piezoelectric layer are equal or nearly equal.

[0026] In one achievable manner, based on applying voltage to the plurality of second electrodes, the resonator is used to excite the piezoelectric transducer layer to generate a first resonance mode, wherein a vibration direction of the first resonance mode is perpendicular to a surface of the substrate.

[0027] The first resonance mode is the main resonance mode of the resonator.

[0028] In one achievable manner, the first piezoelectric layer includes a first piezoelectric material, and the second piezoelectric layer includes a second piezoelectric material; the Euler angle of the crystal of the first piezoelectric material is (0°, 0°, 0°), and the Euler angle of the crystal of the second piezoelectric material is (0°, 180°, 0°), wherein the c-axis of the piezoelectric material of the first piezoelectric layer is opposite to the c-axis of the piezoelectric material of the second piezoelectric layer, one of which is facing upward along the thickness of the piezoelectric layer, and the other is facing downward along the thickness of the piezoelectric layer.

[0029] In one possible implementation, the electromechanical coupling coefficient Kt of the resonator is 2 ≥23%.

[0030] In one achievable manner, the material of the piezoelectric transducer layer includes a combination of nitrogen, scandium, and aluminum; the mass fraction of the scandium is greater than or equal to 10%, or may be less than or equal to 40%.

[0031] For example, the mass fraction of scandium may be 25%, 30%, or 40%.

[0032] In one achievable manner, the material of the piezoelectric transducer layer includes a combination of zinc and oxygen, such as zinc oxide. The material of the piezoelectric transducer layer may also include quartz or lead zirconate titanate PZT material.

[0033] In one achievable manner, a dielectric layer is stacked between the substrate and the first electrode, and a thickness g of the dielectric layer satisfies: g=λ / 4, wherein λ is the wavelength of the sound wave of the resonator at the resonant frequency in the material of the dielectric layer.

[0034] By arranging a dielectric layer between the substrate and the first electrode, coupling between the piezoelectric layer and the substrate is prevented, thereby increasing the electromechanical coupling coefficient of the device. Moreover, when the thickness g of the dielectric layer satisfies: g=λ / 4, the electromechanical coupling coefficient can be further improved.

[0035] On the other hand, the present application also provides a filter, which may include a plurality of electrically connected resonators, and at least one of the plurality of resonators may be the resonator mentioned above.

[0036] Since the filter provided in the present application includes the resonator in the above-mentioned implementation structure, and the resonator includes at least two piezoelectric layers with opposite polarization directions, the resonator has a larger electromechanical coupling coefficient. This resonator is applied in the filter to improve the out-of-band suppression performance of the filter.

[0037] On the other hand, the present application further provides a duplexer, which includes a transmitting channel filter and a receiving channel filter, and at least one of the transmitting channel filter and the receiving channel filter can be filtered using the above-mentioned filter.

[0038] On the other hand, the present application also provides a multiplexer, which includes multiple transmit channel filters and multiple receive channel filters, wherein at least one of the multiple transmit channel filters, or at least one of the multiple receive channel filters can adopt the filter involved in the embodiment of the present application.

[0039] On the other hand, the present application also provides an electronic device, which includes an amplifier, and the filter, duplexer or multiplexer in the above-mentioned implementable manner, and the filter, duplexer or multiplexer can be electrically connected to the amplifier.

[0040] The electronic device provided in the embodiment of the present application includes the above-mentioned filter, duplexer or multiplexer. Therefore, the electronic device provided in the embodiment of the present application and the filter, duplexer or multiplexer of the above-mentioned technical solution can solve the same technical problem and achieve the same expected effect.

[0041] In another aspect, the present application further provides a method for preparing a resonator, the method comprising:

[0042] Producing a first electrode on a substrate;

[0043] A first piezoelectric layer is formed on the first electrode, and a second piezoelectric layer is formed on the first piezoelectric layer, wherein the first piezoelectric layer has a first piezoelectric tensor component e 33 , the second piezoelectric layer has a second piezoelectric tensor component e 33 , the first piezoelectric tensor component e 33 and the second piezoelectric tensor component e 33 on the contrary;

[0044] A plurality of second electrodes are manufactured on the second piezoelectric layer, and the plurality of second electrodes are arranged side by side in a first direction.

[0045] In the resonator made by the above method, the piezoelectric transducer layer includes multiple stacked piezoelectric layers, and two adjacent piezoelectric layers have opposite piezoelectric tensor component polarities. In this way, when the resonator is working, resonant coupling will be generated at the interface between the two adjacent piezoelectric layers, thereby improving the electromechanical coupling coefficient of the resonator.

[0046] In one achievable manner, the first piezoelectric layer and the second piezoelectric layer are prepared by using an epitaxial growth technique.

[0047] In one achievable manner, when a plurality of second electrodes are manufactured on the second piezoelectric layer, the method includes: providing a plurality of second electrodes arranged side by side on the second piezoelectric layer, with a gap between two adjacent second electrodes; and opening a groove at a position opposite to the gap including the first piezoelectric layer and the second piezoelectric layer.

[0048] In one achievable manner, the groove passes through the first piezoelectric layer and the second piezoelectric layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of some structures in an electronic device;

[0050] Figure 2 It is a schematic diagram of some structures in an electronic device;

[0051] Figure 3 It is a schematic diagram of a part of the structure of a filter in an electronic device;

[0052] Figure 4 It is a partial structural schematic diagram of a resonator;

[0053] Figure 5 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0054] Figure 6 What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided in an embodiment of the present application;

[0055] Figure 7 What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided by the relevant technology;

[0056] Figure 8 What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided by the relevant technology;

[0057] Fig. 9 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0058] Fig.10 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0059] Fig.11 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0060] Fig.12 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0061] Fig.13 What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided by the relevant technology;

[0062] Fig.14 What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided in an embodiment of the present application;

[0063] Fig.15 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0064] Fig.16 What is shown is a partial structural schematic diagram of a resonator provided in an embodiment of the present application;

[0065] Fig.17A What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided in an embodiment of the present application;

[0066] Fig. 17B What is shown is a structural schematic diagram for reflecting the vibration of a resonator provided by the relevant technology;

[0067] Fig.18A Shown is Fig.17A Admittance curve diagram of the structure shown;

[0068] Fig.18B Shown is Fig. 17B Admittance curve diagram of the structure shown;

[0069] Fig.19 A process flow chart of a resonator preparation method provided in an embodiment of the present application;

[0070] Fig. 20 A schematic diagram of the structure of a filter provided in an embodiment of the present application;

[0071] Fig.21 for Fig. 20 Admittance curves of each resonator and filter bandpass diagram.

[0072] Reference numerals:

[0073] 100- electronic equipment;

[0074] 200 - filter;

[0075] 300-Resonator;

[0076] 400, 410, 420, 430, 440 - resonators;

[0077] 500-antenna;

[0078] 600-Receiver;

[0079] 700 - Transmitter;

[0080] 800-baseband chip;

[0081] 900-switch;

[0082] 60a, 60c, 70a - filter; 60b - low noise amplifier; 60d - mixer; 60e - buffer; 60f, 70d - voltage controlled oscillator; 70b - amplifier; 70c - driver;

[0083] 10-substrate; 101-cavity;

[0084] 20- a first electrode;

[0085] 30- piezoelectric transducer layer; 301- first piezoelectric layer; 302- second piezoelectric layer;

[0086] 40 - second electrode; 401 - first interdigital electrode; 402 - second interdigital electrode;

[0087] 50-dielectric layer;

[0088] 601-first bus bar; 602-second bus bar;

[0089] 70-Groove. DETAILED DESCRIPTION

[0090] Before introducing the structure that can be implemented by the embodiments of the present application, the technical terms involved in the embodiments of the present application are first introduced.

[0091] Piezoelectric effect: includes direct piezoelectric effect and inverse piezoelectric effect. The direct piezoelectric effect refers to the change of the polarization of piezoelectric materials when they are subjected to mechanical force, while the inverse piezoelectric effect refers to the deformation of the material after an external electric field is applied to the piezoelectric material. The main reasons for the piezoelectric effect are the anisotropy of the crystal structure of the piezoelectric material itself and the polarization effect.

[0092] Main resonant mode, parasitic mixed mode: The parasitic resonant frequency generated by the resonator may be close to the main resonant frequency. The parasitic resonance may affect the main resonant mode, thereby affecting the in-band insertion loss performance and out-of-band suppression performance of the filter. The parasitic resonance of the resonator is usually called a mixed mode, or a parasitic mixed mode. When the mixed mode falls near the main resonant mode, for example, near the resonance point and anti-resonance point of the main resonant mode, it will affect the in-band insertion loss performance and out-of-band suppression performance of the filter.

[0093] Piezoelectric coupling factor Kt 2 : is a key parameter of the resonator, the electromechanical coupling coefficient Kt 2It can reflect the conversion efficiency between mechanical energy and electrical energy, and the electromechanical coupling coefficient Kt of the resonator. 2 Determines the relative frequency width between the anti-resonance frequency and the 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 Kt 2 The larger it is, the larger the bandwidth of the filter built with the ladder structure can be, and the better the performance.

[0094] Piezoelectric tensor components: 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 elastic tensor components c ijkl , piezoelectric tensor component e ijk , the 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 kxy 2 It is calculated from the elastic tensor component, piezoelectric tensor component, and dielectric tensor component of the material, and the formula is:

[0095]

[0096] 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.

[0097] 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.

[0098] For the piezoelectric material crystal orientation with Euler angle (0,0,0), taking LN as an example,

[0099] c E 11 =2.03,c E12 =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 ;

[0100] 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 -12F / m. The remaining components can be obtained through 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 , can be expanded accordingly.

[0101] Now for the piezoelectric material crystal orientation with Euler angles (α, β, γ), the corresponding elastic tensor components are Piezoelectric tensor component e pqr ', dielectric tensor component It can be calculated by the following formula:

[0102]

[0103] e pqr '=e ijk A ip A jq A kr ;

[0104]

[0105] The formula uses the Einstein summation convention, where the 3*3 matrix A=(cosαcosγ-sinαcosβsinγ,-cosαsinγ-sinαcosβcosγ,sinαsinβ; sinαcosγ+cosαcosβsinγ,-sinαsinγ+cosαcosβcosγ,-cosαsinβ; sinβsinγ,sinβcosγ,cosβ).

[0106] Euler angle of piezoelectric material: The Euler angle characterizes the relative rotation angle relationship between the X direction or Y direction of the original piezoelectric crystal structure in the wafer plane, which is perpendicular or parallel to the extension direction of the resonator fingers.

[0107] Admittance: In power electronics, admittance is defined as the reciprocal of impedance, symbol Y, and unit is Siemens, referred to as 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.

[0108] Admittance curve abs and admittance curve Re: Admittance curve abs(Y) = |Y|, which is the modulus (also called amplitude) of Y, representing the overall response of the resonator. Re(Y) is the real part of Y, that is, the conductance G, representing the loss of the resonator.

[0109] The embodiment of the present application provides an electronic device, which includes but is not limited to products such as a radio frequency front end and a filter amplifier module, and may also include mobile phones, tablet computers (pads), smart wearable products (e.g., smart watches, smart bracelets), virtual reality (VR) devices, augmented reality (AR), drones and other terminal devices, or may also be base stations, televisions, routers, cars and other devices. The embodiment of the present application does not impose any special restrictions on the specific form of the above electronic devices.

[0110] In electronic devices such as those described above, Figure 1 As shown, the electronic device 100 may include a filter 200, which can effectively filter out a specific frequency point in the signal or frequencies other than the frequency point 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.

[0111] Figure 2 A partial circuit diagram of some electronic devices 100 is given. 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 through a switch 900, and the receiver 600 and the transmitter 700 are electrically connected to the baseband chip 800.

[0112] exist Figure 2 The receiver (Receiver) 600 shown includes a filter (Filter) 60a and a filter (Filter) 60c, a low noise amplifier 60b is electrically connected between the filter 60a and the filter 60c, the filter 60c is electrically connected to the buffer (Buffer) 60e through the mixer (Mixer) 60d, and the buffer 60e is electrically connected to the voltage-controlled oscillator 60f. Figure 2 This is only an exemplary receiver, and electronic components may be increased or reduced based on this circuit structure.

[0113] exist Figure 2 The transmitter 700 shown includes a power amplifier (PA) 70b, which is electrically connected to a filter 70a and a driver 70c, respectively, and the driver 70c is electrically connected to a voltage-controlled oscillator 70d. Similarly, Figure 2This is only an exemplary transmitter, and electronic components may be increased or reduced based on this circuit structure.

[0114] For example, in Figure 2 In the transmitter 700 shown, the filter can effectively filter out the frequency point of a specific frequency or frequencies other than the frequency point after being amplified by the power amplifier, or the filter can filter out the noise signals of the low noise amplifier.

[0115] For example Figure 3 As shown, the filter 200 may include a plurality of resonators 300 connected in series, or a plurality of resonators 300 connected in parallel, or a combination of resonators 300 connected in series and in parallel.

[0116] At least one of the plurality of resonators included in the filter 200 may be Figure 4 The resonator shown.

[0117] like Figure 4 , Figure 4 The figure shows a part of a process structure diagram of a resonator. The resonator includes a substrate 10, a first electrode 20, a piezoelectric transducer layer 30 and a plurality of second electrodes 40, wherein the first electrode 20, the piezoelectric transducer layer 30 and the plurality of second electrodes 40 are arranged on the substrate 10. The plurality of second electrodes 40 are arranged side by side in a first direction, the piezoelectric transducer layer 30 has a first side and a second side, the plurality of second electrodes 40 are located on the first side, the first electrode 20 is located on the second side, the first side is away from the substrate 10, and the second side is toward the substrate 10. For example, Figure 4 As shown, the piezoelectric transducer layer 30 is stacked between the first electrode 20 and the plurality of second electrodes 40 .

[0118] Above Figure 4 In the exemplary resonator, the plurality of second electrodes 40 are arranged along a first direction, and the first direction can be understood as a direction perpendicular to or nearly perpendicular to the extension direction of the second electrodes 40. In one embodiment, the first direction is perpendicular to the stacking direction of the piezoelectric transducer layer 30 and the first and second electrodes 20 and 40.

[0119] Figure 4 The example structure can be used in a bulk acoustic wave resonator. The main working principle of the bulk acoustic wave resonator is to use 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 filter out unnecessary signals and noise and improve the quality of the signal reception.

[0120] Figure 4When the resonator shown is working, the first electrode 20 may not be connected to an electrical signal, and an alternating voltage of a certain frequency is applied to the second electrode 40, so that an electric field E is generated between the first electrode 20 and the second electrode 40 along the thickness direction of the piezoelectric transducer layer 30, and the piezoelectric transducer layer 30 uses the electric field to form a piezoelectric effect. Figure 4 An example is to use the vertical electric field E to excite the piezoelectric transducer layer 30 to generate resonance, thereby generating conversion between electrical energy and mechanical energy.

[0121] Figure 4 The resonator shown is excited to resonate in the thickness direction of the piezoelectric transducer layer 30, and in one embodiment, can be referred to as a vertically-excited bulk acoustic resonator (YBAR). The thickness direction of the piezoelectric transducer layer 30 here can be understood as the direction on the piezoelectric transducer layer 30 parallel to the stacking direction of multiple membrane layers (substrate, first electrode, piezoelectric layer).

[0122] See Figure 4 Since the portion of the piezoelectric transducer layer 30 close to the first electrode 20 (such as Figure 4 The Q region (shown as a dotted line frame) is attached to the first electrode 20, which will limit the region (such as Figure 4 The acoustic resonance vibration of the Q region (shown as a dotted line frame) limits the vibration amount of the piezoelectric transducer layer 30, resulting in the electromechanical coupling coefficient Kt of the resonator. 2 It is too small to be used in a larger passband bandwidth. For example, it cannot meet the passband bandwidth of the Sub-6GHz to Sub-15GHz frequency band.

[0123] In order to improve the electromechanical coupling coefficient Kt of the resonator 2 , this application exemplifies some novel resonator process structures, as shown below.

[0124] like Figure 5 , Figure 5 is a process structure diagram of a resonator given in an embodiment of the present application. Figure 4 The same thing is that the resonator includes a substrate 10, a first electrode 20 stacked on the substrate 10, a piezoelectric transducer layer 30 and a plurality of second electrodes 40; and the same thing also includes that the second electrode 20 has a first surface and a second surface back to back, the first surface is closer to the piezoelectric transducer layer 30 than the second surface, and the second surface of the first electrode 20 is completely disposed on the substrate 10. Such a resonator can be called a solid substrate resonator.

[0125] Figure 5 The examples shown and Figure 4 The differences include: Figure 5In the embodiment, the piezoelectric transducer layer 30 includes multiple layers stacked together, for example, Figure 5 The piezoelectric transducer layer 30 is exemplarily shown to include a first piezoelectric layer 301 and a second piezoelectric layer 302 which are stacked. In other examples, more piezoelectric layers may be included, for example, three layers, four layers or more layers.

[0126] In a multilayer piezoelectric layer, some piezoelectric tensor components of two adjacent piezoelectric layers are opposite. Figure 5 , the first piezoelectric layer 301 has a first piezoelectric tensor component, the second piezoelectric layer 302 has a second piezoelectric tensor component, and the first piezoelectric tensor component and the second piezoelectric tensor component are opposite. That is, it can be understood that in the example of the present application, adjacent piezoelectric layers have opposite piezoelectric tensor component polarities.

[0127] In some examples, the substrate 10 may be a high acoustic velocity substrate, for example, any one of silicon carbide (SiC), diamond, boron nitride (BN), or a combination of multiple materials.

[0128] The first electrode 20 can be made of any possible conductive metal, including but not limited to Al, Cu, W, Mo, Ru, Pt, etc., and can also be made of 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.

[0129] The second electrode 40 may be made of any possible conductive metal, including but not limited to Al, Cu, W, Mo, Ru, Pt, etc.

[0130] The first electrode 20 and the second electrode 40 may be made of the same conductive metal or different conductive metals.

[0131] In this example, the first piezoelectric layer 301 has a first piezoelectric tensor component e 33 , the second piezoelectric layer 302 has a second piezoelectric tensor component e 33 , where the first piezoelectric tensor component e 33 and the second piezoelectric tensor component e 33 The two piezoelectric layers are opposite (i.e., opposite in number to each other), so that the two piezoelectric layers have opposite polarities of piezoelectric tensor components.

[0132] In some examples, the first piezoelectric layer 301 and the second piezoelectric layer 302 may both include a wurtzite structure, for example, a combination of nitrogen and aluminum, or a combination of nitrogen, scandium and aluminum. For example, an AlScN material may be included. In AlScN, the mass fraction of Sc may be greater than or equal to 0 and less than or equal to 40%. In some examples, the mass fraction of Sc may be greater than or equal to 10%, for example, the mass fraction of Sc may be 20%, 30%, 35% or 40%.

[0133] In some other examples, the first piezoelectric layer 301 and the second piezoelectric layer 302 may both include a combination of oxygen and zinc, for example, zinc oxide. The first piezoelectric layer 301 and the second piezoelectric layer 302 may also include quartz or lead zirconate titanate PZT material.

[0134] Piezoelectric materials such as the above examples including a combination of nitrogen, scandium and aluminum, or zinc oxide each contain a piezoelectric tensor component e 33 , the present application can make the piezoelectric tensor component e in two adjacent piezoelectric layers 33 They are opposite numbers.

[0135] In this application example, the piezoelectric tensor component e of the piezoelectric layer 33 Under the action, the resonator vibrates along the stacking direction of the first piezoelectric layer 301 and the second piezoelectric layer 302 .

[0136] In some examples, the first piezoelectric layer 301 and the second piezoelectric layer 302 both include AlScN, and when the Euler angle of the piezoelectric material of the first piezoelectric layer 301 is (0°, 90°, 0°), the piezoelectric tensor component e of the first piezoelectric layer 301 is 33 = +2.42, when the crystal Euler angle of the piezoelectric material of the second piezoelectric layer 302 is (0°, 270°, 0°), the piezoelectric tensor component e of the second piezoelectric layer 302 33 =-2.42.

[0137] The c-axis of the piezoelectric material of the first piezoelectric layer is opposite to the c-axis of the piezoelectric material of the second piezoelectric layer, one of which is upward along the thickness of the piezoelectric layer, and the other is downward along the thickness of the piezoelectric layer.

[0138] Figure 6 This application is shown as an example Figure 5 The structure shown improves the electromechanical coupling coefficient Kt 2 The principle.

[0139] exist Figure 6 In the embodiment, the first piezoelectric layer 301 and the second piezoelectric layer 302 may both include AlScN, and the piezoelectric tensor component e of the first piezoelectric layer 301 is 33 and the piezoelectric tensor component e of the second piezoelectric layer 302 33On the contrary, the vibration directions of the first piezoelectric layer 301 and the second piezoelectric layer 302 are both along direction 3. The first piezoelectric layer 301 is arranged closer to the first electrode 20 than the second piezoelectric layer 302. Figure 6 The second electrode 401 and the second electrode 402 in the second electrode are exemplarily shown. Figure 6 The fill pattern in shows the approximate area where the resonator vibrates.

[0140] For example, when a positive voltage is applied to the second electrode 401 , the first piezoelectric layer 301 may be compressed along direction 3 and the second piezoelectric layer 302 may be stretched along direction 3 because the first piezoelectric layer 301 and the second piezoelectric layer 302 have opposite piezoelectric tensor component polarizations.

[0141] When the second piezoelectric layer 302 is stretched along direction 3, the portion of the second piezoelectric layer 302 close to the second electrode 401 (eg Figure 6 The A1 portion of the second piezoelectric layer 302 (eg, the A1 portion of the second piezoelectric layer 302) vibrates upward, and the portion of the second piezoelectric layer 302 that is close to the first piezoelectric layer 301 (eg, Figure 6 When the first piezoelectric layer 301 is compressed along direction 3, the portion of the first piezoelectric layer 301 close to the second piezoelectric layer 302 (such as Figure 6 The C1 portion of the first piezoelectric layer 301 vibrates downward, and the portion of the first piezoelectric layer 301 close to the first electrode 20 (such as Figure 6 The D1 part of the device vibrates upward.

[0142] like Figure 6 , located between the second electrode 401 and the first electrode 20, at the bonding position of the first piezoelectric layer 301 and the second piezoelectric layer 302, the two downward vibrations are coupled, so that mechanical vibrations are generated inside the entire piezoelectric layer.

[0143] For another example, when a negative voltage is applied to the second electrode 401 , since the first piezoelectric layer 301 and the second piezoelectric layer 302 have opposite piezoelectric tensor component polarizations, the first piezoelectric layer 301 may be stretched along direction 3 and the second piezoelectric layer 302 may be compressed along direction 3 .

[0144] When the second piezoelectric layer 302 is compressed along direction 3, the portion of the second piezoelectric layer 302 close to the second electrode 401 (eg Figure 6 The A2 portion of the second piezoelectric layer 302 (eg, the A2 portion of the second piezoelectric layer 302) vibrates downward, and the portion of the second piezoelectric layer 302 that is close to the first piezoelectric layer 301 (eg, Figure 6 When the first piezoelectric layer 301 is stretched along direction 3, the portion of the first piezoelectric layer 301 close to the second piezoelectric layer 302 (such as Figure 6 The C2 portion of the first piezoelectric layer 301 vibrates upward, and the portion of the first piezoelectric layer 301 close to the first electrode 20 (such as Figure 6 The D2 part of the device vibrates downward.

[0145] like Figure 6 , located between the second electrode 402 and the first electrode 20, at the bonding position of the first piezoelectric layer 301 and the second piezoelectric layer 302, the two upward vibrations are coupled, so that mechanical vibrations are generated inside the entire piezoelectric layer.

[0146] Therefore, the example of this application Figure 6 In the resonator structure, when the polarities of the piezoelectric tensor components of adjacent piezoelectric layers are opposite, the multilayer piezoelectric layers will produce coupled resonance at the interface, increasing the electromechanical coupling coefficient Kt 2 .

[0147] In the example of the present application, since there is a gap between the second electrode 401 and the second electrode 402, compared with the resonator (such as the film cavity acoustic resonator FBAR) in which the second electrode 401 and the second electrode 402 are connected as one body, the present application Figure 6 The second electrode 401 in the embodiment will not be constrained by the second electrode 402, and has a greater degree of freedom. Figure 6 , the second electrode 402 can also vibrate along direction 3 to increase the vibration amount of the entire resonator.

[0148] Similarly, since there is a gap between the second electrode 401 and the second electrode 402, compared with the resonator (such as the film cavity acoustic resonator FBAR) in which the second electrode 401 and the second electrode 402 are connected as one body, the present application Figure 6 The second electrode 402 in the embodiment will not be constrained by the second electrode 401 or other second electrodes, so that the second electrode 402 has a greater degree of freedom, and thus, Figure 6 , the second electrode 402 can also vibrate along direction 3 to increase the vibration amount of the entire resonator.

[0149] In this way, the electromechanical coupling coefficient Kt of the resonator can be further improved. 2 .

[0150] Figure 7 The vibration diagram when a piezoelectric layer is used is shown as an example. The portion of the piezoelectric transducer layer 30 that is in contact with the second electrode 401 (eg Figure 7 The A1 portion of the piezoelectric transducer layer 30 (eg, Figure 7 The B1 part of the vibrates downward.

[0151] and the above Figure 6 In comparison, Figure 7 In the embodiment of the present application, the interior of the piezoelectric transducer layer 30 basically does not generate vibration. Figure 6In the embodiment, not only the upper and lower surfaces of the piezoelectric layer will vibrate, but also the interface of the adjacent piezoelectric layer will vibrate. In some scenarios, even if the vibration of the part where the piezoelectric layer and the first electrode 20 are attached is limited, the resonator of the example of the present application can still improve the electromechanical coupling coefficient Kt. 2 .

[0152] Figure 6 and Figure 7 compared to, Figure 6 The sum of the thickness of the first piezoelectric layer 301 and the second piezoelectric layer 302 is 2h, and Figure 7 The thickness of the piezoelectric transducer layer 30 is substantially equal or nearly equal. Figure 6 The resonant frequency and Figure 7 The resonant frequencies are substantially the same or nearly the same.

[0153] This application example Figure 6 Resonator, on the basis of ensuring that the resonant frequency meets the requirements, can also improve the electromechanical coupling coefficient Kt 2 .

[0154] The direction 3 involved in the embodiment of the present application can be understood as: a direction perpendicular to the surface of the substrate 10, or parallel to the stacking direction of the first piezoelectric layer 301 and the second piezoelectric layer 302. The direction 1 can be understood as: parallel to the surface of the substrate 10 and perpendicular to the extension direction of the second electrode 40. The direction 2 can be understood as: parallel to the extension direction of the second electrode 40.

[0155] In some examples, in order to increase the resonant frequency, it is also possible to use Figure 8 The resonator shown, Figure 8 and Figure 7 In comparison, Figure 8 In the embodiment, the thickness of the piezoelectric transducer layer 30 of the one-layer structure is h. Figure 7 The thickness of the piezoelectric transducer layer 30 in the one-layer structure is 2h. For example, Figure 7 In the case of Figure 8 In the embodiment, the resonant frequency can be 2f, that is, the resonant frequency of the resonator can be increased by reducing the thickness of the piezoelectric transducer layer 30. However, in the process, when the resonant frequency is increased by thinning the thickness of the piezoelectric transducer layer 30, it may pose a greater challenge to the photolithography technology. Therefore, the increase of the resonant frequency is subject to certain limitations. Figure 7 and Figure 8 The high-frequency applications of the resonators shown are limited.

[0156] However, using Figure 6 In the resonator shown, the limitations of lithography technology are relaxed by stacking multiple piezoelectric layers, so that the resonator can be used in the high frequency range while improving the stability and firmness of the resonator.

[0157] Fig. 9 1 is a process structure diagram of another resonator exemplified in the present application. In the resonator, a cavity 101 is provided in the substrate 10. Such a resonator can be called a cavity-type suspended piezoelectric thin film resonator.

[0158] exist Fig. 9 In the embodiment, the second electrode 20 has a first surface and a second surface facing back to back, the first surface is closer to the piezoelectric transducer layer 30 than the second surface, the substrate 10 is provided with a cavity 101, at least a portion of the second surface of the first electrode 20 is used to enclose the cavity 101, and at least a portion of the first electrode 20 is arranged between the cavity 101 and the piezoelectric transducer layer 30.

[0159] In this example, the piezoelectric transducer layer 30 may also include multiple layers stacked, for example, a first piezoelectric layer 301 and a second piezoelectric layer 302 stacked. In the multiple piezoelectric layers, adjacent piezoelectric layers have opposite polarities of piezoelectric tensor components. For example, the piezoelectric tensor component e of the first piezoelectric layer 301 is 33 and the piezoelectric tensor component e of the second piezoelectric layer 302 33 on the contrary.

[0160] Fig.10 , Fig.11 and Fig.12 2 is a process structure diagram of another three resonators provided in the embodiment of the present application. In this example, a dielectric layer 50 is also included, and the dielectric layer 50 is stacked between the substrate 10 and the first electrode 20. For example, the dielectric layer 50 can be silicon oxide (SiO2).

[0161] In some examples, the thickness g of the dielectric layer 50 satisfies: g=λ / 4, where λ is the wavelength of the sound wave of the resonator at the resonant frequency in the material of the dielectric layer 50 .

[0162] like Fig.13 and Fig.14 ,exist Fig.13 In the embodiment, the piezoelectric transducer layer 30 includes a piezoelectric layer. Fig.14 In the embodiment, the piezoelectric transducer layer 30 includes a first piezoelectric layer 301 and a second piezoelectric layer 302 stacked together, and further includes a dielectric layer 50 stacked between the substrate 10 and the first electrode 20.

[0163] exist Fig.13 In the embodiment, since the first electrode 20 of the metal layer is directly stacked on the substrate 10, the vibration amplitude of the piezoelectric transducer layer 30 and the first electrode 20 is limited, such as Fig.13 As shown, the vibration area and amplitude are small. Fig.14 As shown, because a dielectric layer with less hardness is stacked between the substrate 10 and the first electrode 20, and Fig.13In comparison, mechanical vibrations will also be generated in the first electrode 20 and the dielectric layer 50, thereby increasing the vibration amount of the entire resonator and increasing the electromechanical coupling coefficient Kt. 2 .

[0164] Back to Figures 10 to 12 The resonator is further provided with a groove 70 , and there is a gap between two adjacent second electrodes 40 . The groove 70 is provided in the piezoelectric transducer layer 30 , and the groove 70 is opposite to the gap, that is, it can be understood that the groove 70 is connected with the gap.

[0165] In some examples, such as Fig.10 and Fig.11 , the first piezoelectric layer 301 is closer to the substrate 10 than the second piezoelectric layer 302, and the groove 70 can penetrate the second piezoelectric layer 302 and a portion of the first piezoelectric layer 301. In some other examples, such as Fig.12 The groove 70 may penetrate the second piezoelectric layer 302 and the first piezoelectric layer 301 to the surface of the first electrode 20 .

[0166] That is, it can be understood that, in the example of the present application, the groove 70 may penetrate part of the piezoelectric transducer layer 30 , or may penetrate the entire piezoelectric transducer layer 30 , reaching the surface of the first electrode 20 .

[0167] By opening grooves in the multilayer piezoelectric layer, the limitation of the piezoelectric layer can be reduced, further increasing the electromechanical coupling coefficient Kt of the resonator. 2 , and, the groove 70 also helps to suppress or frequency shift parasitic modes.

[0168] In some implementation structures, the deeper the groove 70 is, the greater the electromechanical coupling coefficient Kt of the resonator is. 2 In the embodiment of the present application, if Fig.11 , the depth h of the groove 70 can satisfy: 30%H≤h≤H, where H is the thickness of the piezoelectric transducer layer 30. For example, h=50%H, h=60%H, h=70%H, h=80%H, h=90%H or h=H.

[0169] Furthermore, in some practicable examples, the radial dimension of the groove 70 gradually decreases from the top surface to the bottom surface. Fig.11 , the inclination angle α of the groove 70 may be: 45°≤α≤90°. Fig.11 In the figure, the inclination angle α is about 60°. Fig.10 and Fig.12 In the embodiment, the inclination angle α is about 90°.

[0170] The inclination angle α of the groove 70 may be understood as the angle between the side surface of the groove 70 and a reference plane, where the reference plane is a plane parallel to the surface of the substrate 10 .

[0171] Fig.15 A process structure diagram of a resonator according to an embodiment of the present application is shown. Fig.16 Shows Fig.15 Distribution diagram of the second electrode in .

[0172] exist Fig.15 and Fig.16 In the exemplary resonator, the plurality of second electrodes include a plurality of first interdigital electrodes 401 and a plurality of second interdigital electrodes 402. For example, along a direction perpendicular to the extension direction of the first interdigital electrodes 401, the plurality of first interdigital electrodes 401 and the plurality of second interdigital electrodes 402 may be arranged side by side, and the plurality of first interdigital electrodes 401 and the plurality of second interdigital electrodes 402 may be arranged at intervals, that is, a second interdigital electrode 402 may be arranged between two adjacent first interdigital electrodes 401. Alternatively, the first interdigital electrodes 401 and the second interdigital electrodes 402 are spaced apart in the first direction, and the extension direction of the first interdigital electrodes 401 and / or the second interdigital electrodes 402 is perpendicular to the first direction.

[0173] The plurality of first interdigital electrodes 401 are connected via the first bus bar 601, and the plurality of second interdigital electrodes 402 are connected via the second bus bar 602. For example, the first bus bar 601 and the second bus bar 602 are arranged in parallel, and the first bus bar 601 and the second bus bar 602 both extend in a direction perpendicular to the extending direction of the first interdigital electrodes 401 or the second interdigital electrodes 402, such as Fig.16 As shown, the first bus bar 601 and the second bus bar 602 extend along a first direction.

[0174] The pitch P can be understood as Fig.16 As shown, the width of each first interdigital electrode 401 is t1, the spacing between each two adjacent first interdigital electrodes 401 and second interdigital electrodes 402 is t2, and the finger pitch (Pitch) P is the sum of the width t1 and the spacing t2.

[0175] In some examples, the width dimension t1 of the plurality of first interdigital electrodes 401 has a process tolerance, and the interval t2 between two adjacent first interdigital electrodes 401 and second interdigital electrodes 402 also has a process tolerance.

[0176] The thickness of the piezoelectric layer, the thickness of the first electrode, and the thickness of the second electrode are the thicknesses along the stacking direction of the multiple film layer structures (eg Fig.15 L direction), the height dimension of the piezoelectric layer, the height dimension of the first electrode, and the height dimension of the second electrode.

[0177] The duty ratio is the ratio of the width t1 of the first interdigital electrode 401 to the interdigital pitch P, or the ratio of the width of the second interdigital electrode 402 to the interdigital pitch P. In some examples, the width of the first interdigital electrode 401 is equal to the width of the second interdigital electrode 402.

[0178] When the resonator is working, acoustic loss will occur at the electrode, reducing the performance of the device, such as Fig.15 In the embodiment, acoustic loss may be generated at the first electrode 20 or at the second electrode 40. In order to reduce the electrode acoustic loss, in some examples, the thickness of the electrode may be reduced. However, when the thickness of the electrode is reduced, the power tolerance of the electrode is weakened, shortening the service life of the device.

[0179] In the resonator of the example of the present application, by adopting a multi-layer stacked piezoelectric layer, the thickness of the entire piezoelectric layer is increased, thereby reducing the ratio of the thickness of the electrode layer to the thickness of the entire piezoelectric layer. By using a thicker piezoelectric layer, the acoustic loss in the electrode can be reduced, thereby also ensuring the power tolerance of the electrode.

[0180] In some examples, such as Fig.15 The thickness of the second electrode layer 40 is S1, and the sum of the thickness of the first piezoelectric layer and the second piezoelectric layer is S2, wherein S1 / S2≤0.35. For example, S1 / S2≤0.3, and for another example, S1 / S2≤0.2. For another example, S1 / S2≤0.1.

[0181] In some examples, the thickness of the first electrode is S3, and the sum of the thickness of the first piezoelectric layer and the second piezoelectric layer is S2, wherein S3 / S2≤0.35, for example, S3 / S2≤0.3, for example, S3 / S2≤0.2, and for example, S3 / S2≤0.1.

[0182] In order to increase the resonant frequency of the resonator, in some examples, the Fig.16 However, when the finger pitch is reduced, it will bring challenges to the photolithography technology. In the example of the present application, the finger pitch P can satisfy the thickness of the piezoelectric transducer layer 30: P / d≥1.

[0183] In some examples, the resonant frequency of the resonator can be greater than or equal to 3.64 GHz, for example, can reach 4.34 GHz.

[0184] The following is a comparison of the electromechanical coupling coefficient of the resonator given in the embodiment of the present application and the resonator in the related art with reference to the accompanying drawings and table data.

[0185] Fig.17A is a process structure diagram of a resonator given in an embodiment of the present application, Fig.17AUsed to show the vibration along direction 3.

[0186] Fig. 17B This is a process structure diagram of a resonator with a piezoelectric layer. Fig. 17B Used to show the vibration along direction 3.

[0187] Fig.17A and Fig. 17B In the embodiments, grooves are opened in the piezoelectric transducer layer, and the grooves penetrate the piezoelectric transducer layer.

[0188] like Fig.17A The second piezoelectric layer 302 vibrates along direction 3 at the position where the second piezoelectric layer 302 is attached to the second electrode 401 and the second electrode 402, and the interface between the second piezoelectric layer 302 and the first piezoelectric layer 301 vibrates along direction 3. Also, the interface between the first electrode 20 and the dielectric layer 50 vibrates slightly along direction 3.

[0189] like Fig. 17B The piezoelectric transducer layer 30 vibrates along direction 3 at the position where the second electrode 401 and the second electrode 402 are attached, and there is a slight vibration along direction 3 at the interface between the dielectric layer 50 and the first electrode 20 .

[0190] compared to Fig.17A and Fig. 17B , the example of this application Fig.17A , coupled resonance is generated inside the entire piezoelectric layer.

[0191] Fig.18A Is adopted Fig.17A Structure, and the admittance simulation curve obtained by limiting the physical parameters shown in Table 1. Fig.18B Is adopted Fig. 17B The structure and the admittance simulation curve obtained by limiting the physical parameters shown in Table 2.

[0192]

[0193] Table 1

[0194]

[0195] Table 2

[0196] The Sc mass fractions in Table 1 and Table 2 are examples of the present application. The materials of the first piezoelectric layer 301 and the second piezoelectric layer 302 may include AlScN, and the Sc mass fraction may be 40%.

[0197] Comparing Table 1 and Table 2, the physical parameters of the resonators of the two different structures are equal in terms of the stripe spacing P, the duty cycle, the second electrode thickness, the first electrode thickness, and the dielectric layer thickness. Since the Euler angles of the two piezoelectric layer materials in Table 1 are rotated 180°, the piezoelectric polarization directions of the first piezoelectric layer and the second piezoelectric layer are opposite.

[0198] Fig.18A The admittance simulation curve and Fig.18B The admittance simulation curve of shows the modulus (abs) and real part (Re) of the admittance curve.

[0199] contrast Fig.18A The admittance simulation curve, and Fig.18B From the admittance simulation curve, we can know that: Fig.17A Resonator, the electromechanical coupling coefficient Kt 2 Reached 23.1%, adopted Fig. 17B When the piezoelectric layer is shown, the electromechanical coupling coefficient Kt 2 It is 20.3%. Obviously, when a groove is opened in the piezoelectric layer and multiple piezoelectric layers with opposite polarities are included, the electromechanical coupling coefficient Kt can be increased. 2 .

[0200] In some embodiments, the electromechanical coupling coefficient Kt of the resonator of the present application example is 2 It can be greater than or equal to 23%. For example, it can be 25%, 30%, or even greater.

[0201] Continue reading Fig.18A and Fig.18B Therefore, the resonator including at least two piezoelectric layers in this example can not only improve the electromechanical coupling coefficient and increase the resonance frequency, but also suppress the parasitic mode and further optimize the resonator performance.

[0202] The present application also provides a method for preparing a resonator including multiple piezoelectric layers, such as Fig.19 , Fig.19 The flowchart of the preparation method of the resonator is shown as an example, and the preparation method comprises:

[0203] Step S1: forming a first electrode on a substrate.

[0204] The substrate of the example of the present application may be a high acoustic velocity substrate, for example, any one of silicon carbide (SiC), diamond, boron nitride (BN), or a combination of multiple materials.

[0205] Step S2: a first piezoelectric layer is formed on the first electrode, and a second piezoelectric layer is formed on the first piezoelectric layer, wherein the first piezoelectric layer has a first piezoelectric tensor component e33 , the second piezoelectric layer has a second piezoelectric tensor component e 33 , the first piezoelectric tensor component e 33 and the second piezoelectric tensor component e 33 on the contrary.

[0206] Among some selectable materials, the material of the first piezoelectric layer and the second piezoelectric layer may include AlScN.

[0207] When preparing the first piezoelectric layer and the second piezoelectric layer, an epitaxial growth technique may be used. In addition, the epitaxial growth technique also makes it easier to control the polarization direction of the piezoelectric layer.

[0208] Step S3: a plurality of second electrodes are fabricated on the second piezoelectric layer, and the plurality of second electrodes are arranged side by side in a first direction, which may be perpendicular to the stacking direction of the multi-layer piezoelectric layer.

[0209] The first electrode 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.) can be selected. 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.

[0210] The second electrode can be made of any possible conductive metal (including but not limited to Al, Cu, W, Mo, Ru, Pt, etc.). The first electrode 20 and the second electrode 40 can be made of the same conductive metal or different conductive metals.

[0211] The solid-state substrate piezoelectric thin film resonator or the cavity-type suspended piezoelectric thin film resonator mentioned above can be used as a sensor, for example, a temperature, humidity sensor, pressure sensor, etc. Or, it can also be used as a delay line device and applied to various high-frequency signal processing such as 100MHz-30GHz.

[0212] Furthermore, the above-mentioned cavity-type suspended piezoelectric thin film resonator or solid substrate piezoelectric thin film resonator can be Fig. 20 The electrical connection is implemented in a trapezoidal structure to realize a filter for radio frequency communication. In the filter, there can be resonators connected in series or in parallel, and the resonant frequency of the parallel resonator can be lower than the resonant frequency of the series resonator.

[0213] Fig. 20In the example, resonators 400, 410, 420, 430 and 440 are included. Resonators 400, 410 and 420 are series resonators, and resonators 430 and 440 are parallel resonators. At least one resonator among resonators 400 to 440 may be the resonator involved in the above-mentioned embodiment.

[0214] In some examples, such as Fig.21 , Fig.21 Shown is Fig. 20 The relationship between the admittance curve of each resonator in the ladder filter and the transmission loss curve of the filter. Fig.21 The resonance point of the series resonator (such as resonator 400, resonator 410 and resonator 420) and the anti-resonance point of the parallel resonator (such as resonator 430 and resonator 440) are located in the passband frequency band, forming the passband of the filter, the anti-resonance point of the series resonator (such as resonator 400, resonator 410 and resonator 420) is located on the high-frequency side outside the passband, and the resonance point of the parallel resonator (such as resonator 430 and resonator 440) is located on the low-frequency side outside the passband, thereby making the filter have the characteristics of high roll-off and high out-of-band suppression.

[0215] 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.

[0216] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A resonator, characterized in that: include: substrate; A first electrode, a piezoelectric transducer layer and a plurality of second electrodes, wherein the first electrode, the piezoelectric transducer layer and the plurality of second electrodes are arranged on the substrate, the piezoelectric transducer layer has a first side and a second side, the plurality of second electrodes are located on the first side and arranged side by side in a first direction, the first electrode is located on the second side, the first side faces away from the substrate, and the second side faces the substrate; The piezoelectric transducer layer comprises a first piezoelectric layer and a second piezoelectric layer which are stacked; The first piezoelectric layer has a first piezoelectric tensor component e 33 , the second piezoelectric layer has a second piezoelectric tensor component e 33 , the first piezoelectric tensor component e 33 and the second piezoelectric tensor component e 33 on the contrary.

2. The resonator according to claim 1, characterized in that There is a gap between two adjacent second electrodes; The piezoelectric transducer layer has a groove at a position opposite to the gap, and the groove penetrates the gap.

3. The resonator according to claim 2, characterized in that The thickness dimension H of the piezoelectric transducer layer and the depth dimension h of the groove are such that 30% H≤h≤H.

4. The resonator according to claim 2 or 3, characterized in that The first piezoelectric layer is arranged closer to the substrate than the second piezoelectric layer; The second piezoelectric layer has a top surface away from the first piezoelectric layer, the first piezoelectric layer has a bottom surface away from the second piezoelectric layer, and the groove passes through the top surface and the bottom surface.

5. The resonator according to any one of claims 1 to 4, characterized in that: The thickness dimension of the second electrode is S1, the thickness dimension of the piezoelectric transducer layer is H, and S1 / H≤0.

35.

6. The resonator according to any one of claims 1 to 5, characterized in that: The thickness dimension of the first electrode is S2, the thickness dimension of the piezoelectric transducer layer is H, and S2 / H≤0.

35.

7. The resonator according to any one of claims 1 to 6, characterized in that: The resonator further includes: a first bus bar and a second bus bar; One of every two adjacent second electrodes in the plurality of second 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 interdigitated electrodes among the plurality of second electrodes are connected via the first bus bar, and a plurality of the second interdigitated electrodes among the plurality of second electrodes are connected via the second bus bar; The finger spacing P and the thickness dimension H of the piezoelectric transducer layer satisfy: P / H≥1; The width dimension of each first interdigitated electrode is t1, the spacing between each adjacent two first interdigitated electrodes and the second interdigitated electrodes is t2, the finger spacing P=t1+t2, and the width dimension is a dimension parallel to the surface of the substrate and perpendicular to the extension direction of the first interdigitated electrodes.

8. The resonator according to any one of claims 1 to 7, characterized in that: Based on applying voltage to the plurality of second electrodes, the resonator is used to excite the piezoelectric transducer layer to generate a first resonance mode, wherein a vibration direction of the first resonance mode is perpendicular to the surface of the substrate.

9. The resonator according to any one of claims 1 to 8, characterized in that: The electromechanical coupling coefficient Kt of the resonator 2 ≥23%.

10. The resonator according to any one of claims 1 to 9, characterized in that: The material of the piezoelectric transducer layer includes a combination of nitrogen, scandium and aluminum, and the mass fraction of the scandium is greater than or equal to 10%; or, The material of the piezoelectric conversion layer includes a combination of zinc and oxygen.

11. The resonator according to any one of claims 1 to 10, characterized in that The first electrode has a first surface and a second surface facing each other, the second surface is closer to the substrate than the first surface, and the second surface of the first electrode is completely disposed on the substrate.

12. A filter, characterized in that: include: A plurality of electrically connected resonators, at least one of the plurality of resonators being the resonator according to any one of claims 1 to 11.

13. An electronic device, characterized in that: include: Amplifier; The resonator according to any one of claims 1 to 11, or the filter according to claim 12, wherein the resonator or the filter is electrically connected to the amplifier.

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