Resonator, filter, communication chip, and electronic device

Abstract

Embodiments of the present application provide a resonator, a filter, a communication chip, and an electronic device, aiming to solve the problem of a large frequency offset of resonators. According to the resonator, a piezoelectric tensor component e312 of the resonator is used to generate a Zero-order Shear Horizontal mode (SH0 mode for short). The mode is not affected by the thickness of a piezoelectric layer, thereby avoiding the large frequency offset of the resonator caused by uneven thickness of the piezoelectric layer, i.e., reducing the frequency offset of the resonator.

Description

Resonators, filters, communication chips and electronic devices

[0001] This application claims priority to Chinese patent application filed on December 6, 2024, with application number 202411795293.7 and entitled "Resonator, Filter, Communication Chip and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, specifically to a resonator, filter, communication chip, and electronic device. Background Technology

[0003] With the development of communication technology, electronic devices are generally equipped with filters for signal filtering. High-frequency filters typically contain multiple resonators, including horizontally-excited bulk acoustic resonators (XBARs), vertically-excited bulk acoustic resonators (YBARs), and film bulk acoustic resonators (FBARs). Within the same wafer, and especially between different wafers, the piezoelectric layer thickness of the resonators is uneven, leading to significant frequency shifts. Summary of the Invention

[0004] This application provides a resonator, filter, communication chip, and electronic device that can reduce the frequency offset of the resonator.

[0005] In a first aspect, embodiments of this application provide a resonator including a first electrode, a piezoelectric layer, and a plurality of second electrodes. The first electrode is disposed on a first side of the piezoelectric layer, and the plurality of second electrodes are disposed on a second side of the piezoelectric layer. The plurality of second electrodes are spaced apart along a first direction parallel to the piezoelectric layer.

[0006] The piezoelectric layer includes a piezoelectric material, the polarization direction of which is perpendicular to the first direction and parallel to the piezoelectric layer.

[0007] The Euler angles of the piezoelectric crystal are (0°±15°, 45°±15°, 45°±15°), or the crystal cutting angle and propagation direction of the piezoelectric material are (45°±15°)Y cut and (45°±15°)X propagation.

[0008] Alternatively, the Euler angles of the piezoelectric material crystal are (0°±15°, 45°±15°, 135°±15°), or the crystal cutting angle and propagation direction of the piezoelectric material are (45°±15°)Y-cut and (135°±15°)X-propagation; where the X-direction is the first principal axis direction of the piezoelectric material and the Y-direction is the second principal axis direction of the piezoelectric material.

[0009] Alternatively, the Euler angles of the piezoelectric material crystal are (60°±15°, 135°±15°, 45°±15°).

[0010] Alternatively, the Euler angles of the piezoelectric material crystal are (60°±15°, 135°±15°, 135°±15°).

[0011] Alternatively, the Euler angles of the piezoelectric material crystal are (120°±15°, 45°±15°, 45°±15°).

[0012] Alternatively, the Euler angles of the piezoelectric material crystal are (120°±15°, 45°±15°, 135°±15°).

[0013] Alternatively, the Euler angles of the piezoelectric material crystal are (180°±15°, 135°±15°, 45°±15°).

[0014] Alternatively, the Euler angles of the piezoelectric material crystal are (180°±15°, 135°±15°, 135°±15°).

[0015] With the above settings, the piezoelectric tensor component e of the resonator is utilized. 312 The zero-order shear horizontal mode (SH0 mode) is generated. This mode is not affected by the thickness of the piezoelectric layer, which can avoid the large frequency shift of the resonator caused by the uneven thickness of the piezoelectric layer, thus reducing the frequency shift of the resonator.

[0016] In some embodiments that may include the above embodiments, the piezoelectric tensor component e of the resonator 312 ≥1.47C / m 2 Alternatively, the electromechanical coupling coefficient Kt of the resonator 2 ≥10%. This setting can improve the electromechanical coupling coefficient Kt of the resonator. 2 This increases the bandwidth of the filter that uses the resonator.

[0017] In some embodiments that may include the above embodiments, there is a first gap between two adjacent second electrodes, and a first trench is provided on the piezoelectric layer, with the first trench communicating with the first gap.

[0018] By setting the first groove, the piezoelectric tensor component e can be blocked. 112 The SH0 mode is excited, and the first trench can also prevent the piezoelectric tensor component e. 112 The propagation of the excited SH0 mode reduces the interference of this miscellaneous mode on the main mode.

[0019] In some embodiments that may include the above embodiments, the first trench penetrates the piezoelectric layer. This configuration can further prevent the piezoelectric tensor component e from being... 112 Incentive SH0 model.

[0020] In some embodiments that may include the above embodiments, the first trench may not penetrate the piezoelectric layer along its thickness direction. For example, the depth of the first trench may be 50%-80% (50%, 70%, 80%, etc.) of the piezoelectric layer thickness. This configuration can prevent e 112 While stimulating the SH0 mode, avoid damaging the first electrode when fabricating the first trench.

[0021] In some embodiments that may include the above-described embodiments, the resonator further includes a reflective layer and a dielectric layer. The dielectric layer is disposed on the side of the first electrode facing away from the piezoelectric layer, and the reflective layer is disposed on the side of the dielectric layer facing away from the piezoelectric layer. It is understood that the sound velocity in the reflective layer is different from that in the dielectric layer, which can cause sound waves to be reflected at the junction of the reflective layer and the dielectric layer. The sound waves can be reflected back to the dielectric layer at the junction of the reflective layer and the dielectric layer, thereby preventing sound waves from leaking from the dielectric layer.

[0022] In some implementations, the speed of sound propagation within the reflective layer can be greater than the speed of sound propagation within the dielectric layer. The material of the reflective layer includes any one or a combination of silicon carbide, diamond, and boron nitride. This application does not limit the material of the reflective layer.

[0023] In other implementations, the reflective layer includes at least one first reflective layer and at least one second reflective layer, arranged in an alternating stacked configuration, with the first and second reflective layers having different acoustic impedances. In this configuration, the reflective layer constitutes a Bragg reflector, allowing sound waves to be reflected at the junctions of the first and second reflective layers to prevent sound leakage. For example, one of the at least one first reflective layer may be positioned close to the dielectric layer, and correspondingly, the acoustic impedance of the first reflective layer may be higher than that of the dielectric and second reflective layers.

[0024] In some embodiments that may include the above embodiments, the material of the piezoelectric layer includes a combination of oxygen and zinc; or a combination of nitrogen and aluminum; or a combination of tantalum and lithium; or a combination of niobium and lithium; or a combination of tantalum, niobium and lithium.

[0025] In some embodiments that may include the above embodiments, the resonator satisfies: Where f is the resonant frequency of the resonator, V SH Let denoted as , where is the shear wave velocity of the piezoelectric material, P is the distance between the center lines of adjacent second electrodes, and MR is the duty cycle of the second electrode of the resonator. The resonant frequency is directly proportional to the reciprocal of the duty cycle, meaning they are inversely proportional. The resonant frequency can be adjusted by changing the duty cycle. With the same piezoelectric layer material and P, decreasing the duty cycle increases the resonant frequency, allowing filters using this resonator to be suitable for higher frequency signals, such as the sub-6GHz band.

[0026] On the other hand, duty cycle Where p is the distance between the center lines of adjacent second electrodes, and d is the width of the second electrode along the first direction; in the embodiments of this application, the duty cycle of the resonator is small. When P is the same, the width d of the second electrode can be appropriately reduced to avoid the gap between adjacent second electrodes being too small (for example, the gap should not be less than 0.3 μm, and the photolithography difficulty is greater when the gap is less than 0.3 μm), thereby reducing the fabrication difficulty of the resonator (such as reducing the photolithography difficulty).

[0027] In some embodiments that may include the above-described examples, the duty cycle of the second electrode of the resonator is 0.2-0.8. This configuration allows the resonator to have a larger resonant frequency, meeting the requirements for high-frequency applications.

[0028] In some embodiments that may include the above examples, the width of the second electrode along the first direction is 300nm-400nm. This configuration ensures that, when the duty cycle is small, the distance between adjacent second electrodes is neither too large nor too small, facilitating the fabrication of the resonator.

[0029] In some embodiments that may include the above-described examples, the distance between adjacent second electrodes is 0.4 μm to 1.2 μm. When the duty cycle is small, this ensures that the width of the second electrode along the first direction is neither too large nor too small, facilitating the fabrication of the resonator.

[0030] In some embodiments that may include the above examples, the thickness of the piezoelectric layer is 180nm-600nm. This setting ensures that the thickness of the piezoelectric layer is appropriate, so as to prevent the volume of the resonator from being too large or too small.

[0031] In some embodiments that may include the above examples, the thickness of the second electrode is 8nm-120nm. This setting provides a suitable thickness for the second electrode, facilitating its fabrication.

[0032] In some embodiments that may include the above-described embodiments, the resonator further includes a first busbar and a second busbar. The first busbar, the second busbar, and the second electrode are located on the same side of the piezoelectric layer. The first busbar and the second busbar are arranged parallel to each other and spaced apart. A plurality of second electrodes are disposed between the first busbar and the second busbar. The plurality of second electrodes include a plurality of first sub-electrodes and a plurality of second sub-electrodes, which are alternately arranged along a first direction. Each first sub-electrode is coupled to the first busbar, and each second sub-electrode is coupled to the second busbar. With this configuration, the first busbar can receive an input signal and send an output signal to each of the first sub-electrodes, and the second busbar can receive signals from each of the second sub-electrodes to output a signal outside the resonator.

[0033] In some embodiments that may include the above-described examples, the projection of the first electrode onto the piezoelectric layer is located between the projections of the first busbar and the second busbar onto the piezoelectric layer; the projection of the end of the first sub-electrode facing away from the first busbar onto the piezoelectric layer coincides with the projection of the edge of the first electrode onto the piezoelectric layer, and the projection of the end of the second sub-electrode facing away from the second busbar onto the piezoelectric layer coincides with the projection of the edge of the first electrode onto the piezoelectric layer. With this configuration, the first electrode is only located within the aperture region of the resonator, which can improve the performance of the resonator.

[0034] Secondly, embodiments of this application also provide a resonator, comprising: a first electrode, a piezoelectric layer, and a plurality of second electrodes, wherein the first electrode is disposed on a first side of the piezoelectric layer, and the plurality of second electrodes are disposed on a second side of the piezoelectric layer, and the plurality of second electrodes are spaced apart along a first direction parallel to the piezoelectric layer; the piezoelectric tensor component e of the resonator 312 ≥1.47C / m 2 .

[0035] With the above settings, the piezoelectric tensor component e of the resonator is utilized. 312 The zero-order shear horizontal mode (SH0 mode) is generated. This mode is not affected by the thickness of the piezoelectric layer, which can avoid the large frequency shift of the resonator caused by the uneven thickness of the piezoelectric layer, thus reducing the frequency shift of the resonator.

[0036] In some embodiments that may include the above embodiments, there is a first gap between two adjacent second electrodes, and a first trench is provided on the piezoelectric layer, with the first trench communicating with the first gap.

[0037] By setting the first groove, the piezoelectric tensor component e can be blocked. 112 The SH0 mode is excited, and the first trench can also prevent the piezoelectric tensor component e. 112 The propagation of the excited SH0 mode reduces the interference of this miscellaneous mode on the main mode.

[0038] In some embodiments that may include the above embodiments, the first trench penetrates the piezoelectric layer. This configuration can further prevent the piezoelectric tensor component e from being... 112 Incentive SH0 model.

[0039] In some embodiments that may include the above embodiments, the first trench may not penetrate the piezoelectric layer along its thickness direction. For example, the depth of the first trench may be 50%-80% (50%, 70%, 80%, etc.) of the piezoelectric layer thickness. This configuration can prevent e 112 While stimulating the SH0 mode, avoid damaging the first electrode when fabricating the first trench.

[0040] In some embodiments that may include the above embodiments, the resonator further includes a reflective layer and a dielectric layer. The dielectric layer is disposed on the side of the first electrode facing away from the piezoelectric layer, and the reflective layer is disposed on the side of the dielectric layer facing away from the piezoelectric layer. It is understood that the sound velocity in the reflective layer is different from that in the dielectric layer, which can cause sound waves to be reflected at the junction of the reflective layer and the dielectric layer. The sound waves can be reflected back to the dielectric layer at the junction of the reflective layer and the dielectric layer, thereby preventing sound waves from leaking from the dielectric layer.

[0041] In some implementations, the speed of sound propagation within the reflective layer can be greater than the speed of sound propagation within the dielectric layer. The material of the reflective layer includes any one or a combination of silicon carbide, diamond, and boron nitride. This application does not limit the material of the reflective layer.

[0042] In other implementations, the reflective layer includes at least one first reflective layer and at least one second reflective layer, arranged in an alternating stacked configuration, with the first and second reflective layers having different acoustic impedances. In this configuration, the reflective layer constitutes a Bragg reflector, allowing sound waves to be reflected at the junctions of the first and second reflective layers to prevent sound leakage. For example, one of the at least one first reflective layer may be positioned close to the dielectric layer, and correspondingly, the acoustic impedance of the first reflective layer may be higher than that of the dielectric and second reflective layers.

[0043] In some embodiments that may include the above embodiments, the material of the piezoelectric layer includes a combination of oxygen and zinc; or a combination of nitrogen and aluminum; or a combination of tantalum and lithium; or a combination of niobium and lithium; or a combination of tantalum, niobium and lithium.

[0044] In some embodiments that may include the above embodiments, the resonator satisfies: Where f is the resonant frequency of the resonator, V SHLet denoted as , where is the shear wave velocity of the piezoelectric material, P is the distance between the center lines of adjacent second electrodes, and MR is the duty cycle of the second electrode of the resonator. The resonant frequency is directly proportional to the reciprocal of the duty cycle, meaning they are inversely proportional. The resonant frequency can be adjusted by changing the duty cycle. With the same piezoelectric layer material and P, decreasing the duty cycle increases the resonant frequency, allowing filters using this resonator to be suitable for higher frequency signals, such as the sub-6GHz band.

[0045] On the other hand, duty cycle Where p is the distance between the center lines of adjacent second electrodes, and d is the width of the second electrode along the first direction; in the embodiments of this application, the duty cycle of the resonator is small. When P is the same, the width d of the second electrode can be appropriately reduced to avoid the gap between adjacent second electrodes being too small (for example, the gap should not be less than 0.3 μm, and the photolithography difficulty is greater when the gap is less than 0.3 μm), thereby reducing the fabrication difficulty of the resonator (such as reducing the photolithography difficulty).

[0046] In some embodiments that may include the above-described examples, the duty cycle of the second electrode of the resonator is 0.2-0.8. This configuration allows the resonator to have a larger resonant frequency, meeting the requirements for high-frequency applications.

[0047] In some embodiments that may include the above-described embodiments, the resonator further includes a first busbar and a second busbar. The first busbar, the second busbar, and the second electrode are located on the same side of the piezoelectric layer. The first busbar and the second busbar are arranged parallel to each other and spaced apart. A plurality of second electrodes are disposed between the first busbar and the second busbar. The plurality of second electrodes include a plurality of first sub-electrodes and a plurality of second sub-electrodes, which are alternately arranged along a first direction. Each first sub-electrode is coupled to the first busbar, and each second sub-electrode is coupled to the second busbar. With this configuration, the first busbar can receive an input signal and send an output signal to each of the first sub-electrodes, and the second busbar can receive signals from each of the second sub-electrodes to output a signal outside the resonator.

[0048] In some embodiments that may include the above-described examples, the projection of the first electrode onto the piezoelectric layer is located between the projections of the first busbar and the second busbar onto the piezoelectric layer; the projection of the end of the first sub-electrode facing away from the first busbar onto the piezoelectric layer coincides with the projection of the edge of the first electrode onto the piezoelectric layer, and the projection of the end of the second sub-electrode facing away from the second busbar onto the piezoelectric layer coincides with the projection of the edge of the first electrode onto the piezoelectric layer. With this configuration, the first electrode is only located within the aperture region of the resonator, which can improve the performance of the resonator.

[0049] Thirdly, embodiments of this application also provide a filter, including: a plurality of resonators, wherein at least one is a resonator as described above, and at least two of the plurality of resonators are connected in series or in parallel.

[0050] The filters in this application include the resonators in any of the above embodiments, and therefore can achieve the same technical effects and solve the same technical problems.

[0051] Fourthly, embodiments of this application also provide a communication chip, including: a radio frequency front-end circuit, the radio frequency front-end circuit including a power amplifier and / or a low noise amplifier, and a filter as described above, wherein the power amplifier and / or the low noise amplifier are coupled to the filter.

[0052] The communication chip in this application includes the filter in any of the above embodiments, and therefore can achieve the same technical effect and solve the same technical problem.

[0053] Fifthly, embodiments of this application also provide an electronic device, including: an antenna and a communication chip as described above, wherein the communication chip is coupled to the antenna.

[0054] The electronic devices in this application include the communication chips in any of the above embodiments, and therefore can achieve the same technical effects and solve the same technical problems. Attached Figure Description

[0055] Figure 1 is a schematic diagram of the structure of the electronic device provided in an embodiment of this application;

[0056] Figure 2 is a schematic diagram of the structure of the communication chip provided in an embodiment of this application;

[0057] Figure 3 is a schematic diagram of the filter structure provided in an embodiment of this application;

[0058] Figure 4 shows the admittance curves of each resonator in the filter provided in the embodiment of this application and the bandpass curve of the filter;

[0059] Figure 5 is a top view of the resonator provided in an embodiment of this application;

[0060] Figure 6 is a cross-sectional view along direction AA in Figure 5;

[0061] Figure 7 is a schematic diagram of the structure of a single second electrode in the resonator provided in the embodiment of this application;

[0062] Figure 8 is a schematic diagram of the vibration displacement of a single second electrode in the resonator provided in the embodiment of this application;

[0063] Figure 9 is an admittance curve of a single second electrode in the resonator provided in the embodiment of this application;

[0064] Figure 10 is a schematic diagram of the structure of the resonator with the first groove provided in the embodiment of this application;

[0065] Figure 11 shows the case without the first trench. 112 and e 312 Admittance curve of the excited SH0 mode;

[0066] Figure 12 shows the setting of the first trench. 112 and e 312 Admittance curve of the excited SH0 mode;

[0067] Figure 13 is a schematic diagram of another structure of the resonator with the first groove provided in the embodiment of this application;

[0068] Figure 14 is a top view of the resonator provided in the embodiment of this application when the first groove is provided;

[0069] Figure 15 is another top view of the resonator provided in the embodiment of this application when the first groove is provided;

[0070] Figure 16 is a schematic diagram of the resonator with a reflective layer provided in an embodiment of this application;

[0071] Figure 17 is a graph showing the admittance and frequency of the resonator provided in an embodiment of this application.

[0072] Figure 18 is an enlarged view of point A in Figure 17;

[0073] Figure 19 is another admittance and frequency curve of the resonator provided in the embodiment of this application;

[0074] Figure 20 is an enlarged view of point B in Figure 19;

[0075] Figure 21 is a graph showing the admittance and frequency of the resonator provided in the embodiment of this application.

[0076] Figure 22 is an enlarged view of point C in Figure 21.

[0077] Explanation of reference numerals in the attached figures: 11: Frame; 12: Display panel; 13: Back cover; 14: Motherboard; 15: Antenna; 20: Communication chip; 21: RF front-end circuit; 22: Filter; 23: Power amplifier; 24: Low noise amplifier; 200: Resonator; 201: First resonator; 202: Second resonator; 203: Third resonator; 204: Fourth resonator; 205: Fifth resonator; 210: Dielectric layer; 220: First electrode; 230: Piezoelectric layer; 231: First trench; 240: Second electrode; 241: First sub-electrode; 242: Second sub-electrode; 243: First busbar; 244: Second busbar; 250: Reflective layer. Detailed Implementation

[0078] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0079] Before introducing the structures that can be implemented in the embodiments of this application, let's first introduce the technical terms involved in the embodiments of this application.

[0080] The coupling in this application embodiment can be understood as direct coupling and / or indirect coupling. Direct coupling can also be called "electrical connection," which means that components are physically in contact and electrically conductive; it can also be understood as the form in which different components in a circuit structure are connected through physical lines that can transmit electrical signals, such as copper foil or wires on a printed circuit board (PCB). "Indirect coupling" can be understood as two conductors being electrically conductive in a way that is airtight or non-contact. In one embodiment, indirect coupling can also be called capacitive coupling, for example, signal transmission is achieved by forming an equivalent capacitance through coupling between the gaps between two conductive parts.

[0081] Piezoelectric effect: This includes the direct piezoelectric effect and the inverse piezoelectric effect. The direct piezoelectric effect refers to the change in polarization of a piezoelectric material when subjected to mechanical force; while the inverse piezoelectric effect refers to the deformation of a piezoelectric material when an external electric field is applied. The piezoelectric effect is mainly caused by the anisotropy of the crystal structure of piezoelectric materials and their polarization.

[0082] Main resonant mode and parasitic modes: The parasitic resonant frequencies generated by a resonator may be located close to the main resonant frequency. Parasitic resonances can affect the main resonant mode, thereby affecting the filter's in-band insertion loss performance and out-of-band rejection performance. The parasitic resonances of a resonator are commonly referred to as parasitic modes. When parasitic modes fall near the main resonant mode, for example, near the main resonant mode's resonance point and anti-resonant point, they will affect the filter's in-band insertion loss performance and out-of-band rejection performance.

[0083] Piezoelectric coupling factor K t 2 : 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 2This determines the relative frequency width of the resonator's anti-resonance frequency and resonant frequency. For example, when a resonator is used in filter design, this relative frequency width directly determines the filter's bandwidth. The electromechanical coupling coefficient K can be considered as... t 2 The larger the value, the greater the bandwidth of the filter built using the trapezoidal structure, and the better its performance.

[0084] Electromechanical coupling coefficient component k xy 2 For a single-crystal piezoelectric material, it possesses a fourth-order elastic tensor c, a third-order piezoelectric tensor e, and a second-order dielectric tensor ε. According to a right-handed Cartesian coordinate system, it has 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 single-crystal structures, for example c 1323 =c 3132 This simplifies the component order, defining {23,32}→4, {13,31}→5, {12,21}→6, for example, c 1323 =c 3132 →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 components, piezoelectric tensor components, and dielectric tensor components of the material, and the formula is:

[0085] Among them, x={1,2,3}, y={1,2,3,4,5,6}, ε xx S For the dielectric tensor components under constant strain, c yy E These are the elastic tensor components under a fixed electric field strength.

[0086] The following explains the calculation methods and formulas for each elastic tensor component, piezoelectric tensor component, and dielectric tensor component at different Euler angles in different crystals.

[0087] For piezoelectric materials with an Euler angle of (0,0,0), taking lithium niobate (LN) as an example,

[0088] c 11 E =2.03,c12 E =0.53,c 13 E =0.75,c 14 E =0.09,c 44 E =0.60,c 33 E =2.43,c 22 E =c 11 E ,c 23 E =c 13 E ,c 24 E =-c 14 E ,c 55 E =c 44 E ,c 56 E =c 14 E ,c 66 E =(c 11 E -c 12 E ) / 2, unit is *10 11 N / m 2 );

[0089] e 15 =3.70,e 16 =-2.53,e 31 =0.19,e 33 =1.31,e 21 =e 16 ,e 22 =-e 16 ,e 24 =e 15 ,e 32 =e 31 The unit is coulombs per square meter (C / m²). 2 );ε 11 S =43.6*ε0,ε 33 S =29.2*ε0,ε 22 S =ε 11 S Where ε0 is the vacuum permittivity, 8.85 × 10⁻⁶. -12Farads per meter (F / m). The remaining components can be obtained through tensor symmetry; components without numerical values ​​are zero. The components are simplified representations; for the fourth-order elastic tensor components c... ijkl E Third-order piezoelectric tensor component e ijk This can be expanded accordingly.

[0090] For a piezoelectric material with Euler angles (α,β,γ) and crystal orientation, its corresponding elastic tensor component c pqrs ' E piezoelectric tensor component e pqr '、Dielectric tensor component ε pq ' S It can be calculated using the following formula:

[0091] c pqrs ' E =c ijkl E A ip A jq A kr A ls ;

[0092] e pqr '=e ijk A ip A jq A kr ;

[0093] ε pq ' S =ε ij S A ip A jq ;

[0094] The formula uses the Einstein Summation Convention (or Einstein notation), where the 3x3 matrix is:

[0095] electromechanical coupling coefficient K t 2 and electromechanical coupling coefficient component k xy 2 Relationship: Electromechanical coupling coefficient K t 2 From the electromechanical coupling coefficient component k xy 2 The mode is determined by the specific resonator structure and the excitation mode. Generally, the k-mode corresponds to the main resonant mode of the resonator. xy 2 The larger the value, the larger the value of the resonator's K. t 2The larger the value, the greater the potential value. For example, when lithium niobate (LN) is chosen as the piezoelectric material, the maximum electromechanical coupling coefficient component k of LN is significantly larger. xy 2 It can reach 0.9253. Resonators that utilize this component to generate the main resonant mode possess relatively large overall electromechanical coupling performance; for example, the electromechanical coupling coefficient K of the resonator... t 2 It can reach 25%. Furthermore, generally speaking, the electromechanical coupling coefficient component k corresponding to the main resonant mode... xy 2 The larger the value, the more the remaining electromechanical coupling coefficient components k xy 2 The smaller the value, the larger the electromechanical coupling coefficient and the smaller the parasitic modes of the resonator.

[0096] Given a resonator structure, one resonant mode corresponds to one electromechanical coupling coefficient component k. xy 2 For example, the maximum electromechanical coupling coefficient component k of LN xy 2 It can include k 16 2 k 15 2 k 34 2 k 35 2 Excite these maximum electromechanical coupling coefficient components k xy 2 The generated modes are the dominant resonant modes, while the modes generated by the remaining electromechanical coupling coefficient components can be miscellaneous modes. For example, in a horizontally-excited bulk acoustic resonator (XBAR), the excitation of the maximum electromechanical coupling coefficient component k... 16 2 This generates the zero-order shear horizontal mode (SH0 mode), the main resonant mode; in XBAR, the maximum electromechanical coupling coefficient component k is excited. 15 2 This generates the first-order anti-symmetry mode A1 of the main resonant mode; in YBAR, the excitation of the maximum electromechanical coupling coefficient component k 34 2 This generates the first-order shear horizontal mode (SH1) of the main resonant mode.

[0097] Quality Factor (Q): Represents the energy efficiency of a device, that is, the ratio of the total energy received by the device to the energy dissipated within one vibration cycle. In filter design, the electromechanical coupling coefficient K of the resonator that constitutes the filter... t 2 Both the quality factor (Q) and the quality factor (Q) are important parameters.

[0098] Euler angle of piezoelectric materials: Euler angle characterizes the relative rotation angle between the direction of the resonator finger extension and the X or Y direction of the original piezoelectric crystal structure in the wafer plane, which is perpendicular or parallel to the direction of the resonator finger extension.

[0099] Admittance: In power electronics, admittance is defined as the reciprocal of impedance, denoted by Y, and its unit is Siemens (S). Like impedance, admittance is also a complex number, consisting of a real part (conductance G) and an imaginary part (susceptance B): Y = G + jB.

[0100] Admittance curve abs and admittance curve Re: Admittance curve abs(Y) = |Y|, which is the magnitude (also called amplitude) of Y, representing the overall response of the resonator. Re(Y) is the real part of Y, i.e., the conductance G, representing the loss of the resonator.

[0101] 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)).

[0102] Electromechanical coupling R-aR: Based on the relative bandwidth of the resonant frequency fr and the anti-resonant frequency fa, it represents the electromechanical coupling coefficient of the resonator. For example, the R-aR of the resonator should be comparable to the relative bandwidth of the target filter. Where R-aR = (fa - fr) / ((fa + fr) / 2).

[0103] This application provides an electronic device, which may include mobile phones, tablet computers, laptops, smart bracelets, smartwatches, telematics-boxes (T-BOX), and other devices. As shown in Figure 1, taking a mobile phone as an example, the electronic device may include a frame 11, a display panel 12, a back cover 13, and a motherboard 14. The frame 11 forms a mounting cavity, the motherboard 14 is disposed within the mounting cavity, the display panel 12 covers one side of the frame 11, and the back cover 13 covers the other side of the frame 11 to close the mounting cavity. The display panel 12 is electrically connected to the motherboard 14 so that the motherboard 14 can control the display panel 12 to display images.

[0104] In the above implementation, the electronic device also includes an antenna 15 and a communication chip 20. The antenna 15 can be disposed on the frame 11 or on the back cover 13, and the communication chip 20 can be disposed on the motherboard 14. The antenna 15 is coupled to the communication chip 20, and the communication chip 20 can feed power to the antenna 15 so that the antenna 15 emits electromagnetic signals; and / or, the antenna 15 receives electromagnetic signals, and the communication chip 20 can receive signals from the antenna 15. With this configuration, wireless communication between the electronic device and base stations, other electronic devices, satellites, etc., can be realized.

[0105] Referring to Figure 2, in some embodiments, the communication chip 20 may include a radio frequency front-end circuit 21, which includes a filter 22. The filter 22 is coupled to the antenna 15 shown in Figure 1. The filter 22 can realize the coupling between the communication chip 20 and the antenna 15. At the same time, the filter 22 can remove signals that are not needed for communication, thereby avoiding interference and improving communication quality.

[0106] In some implementations, the RF front-end circuit 21 may further include a power amplifier 23, which is coupled to a filter 22. The signal from the signal source passes through the power amplifier 23 and then enters the filter 22. The filter 22 then feeds the signal into the antenna 15 for transmission. The signal source may include a modulator or other device capable of outputting RF signals. The power amplifier 23 is used to increase the signal power to improve the gain of the antenna 15, thereby increasing the transmission distance. The filter 22 can filter out signals outside the communication frequency band.

[0107] In some implementations, the RF front-end circuit 21 may further include a low-noise amplifier 24, which is coupled to a filter 22. After the antenna 15 receives electromagnetic signals from the space, it generates an electrical signal. This signal passes through the filter 22 and then enters the low-noise amplifier 24. The signal output from the low-noise amplifier 24 can be transmitted to a demodulator to achieve signal reception. The filter 22 is used to filter out signals outside the communication frequency band, and the low-noise amplifier 24 can improve the signal-to-noise ratio and the accuracy of the received signal.

[0108] In other implementations, the radio frequency front-end circuit 21 may include a power amplifier 23 and a low-noise amplifier 24. In this case, the radio frequency front-end circuit 21 can transmit and receive signals, thereby improving the communication performance of the electronic device.

[0109] Referring to Figure 3, in this embodiment of the application, the filter 22 includes a plurality of resonators 200, at least two of which are connected in series or in parallel. In one example, the number of resonators can be five, namely, the resonators include a first resonator 201, a second resonator 202, a third resonator 203, a fourth resonator 204, and a fifth resonator 205. The first resonator 201, the second resonator 202, and the third resonator 203 are connected in series, that is, one end of the first resonator 201 is coupled to the input terminal, one end of the second resonator 202 is coupled to the other end of the first resonator, one end of the third resonator 203 is coupled to the other end of the second resonator 202, and the other end of the third resonator is coupled to the output terminal; one end of the fourth resonator 204 is coupled to the other end of the first resonator 201, one end of the fifth resonator 205 is coupled to one end of the third resonator 203, and the other ends of the fourth resonator 204 and the fifth resonator 205 are both grounded.

[0110] Referring to Figures 3 and 4, in the above implementation, the resonant points of the first resonator 201, the second resonator 202, and the third resonator 203 are located within the passband of the filter 22, while the anti-resonant points of the first resonator 201, the second resonator 202, and the third resonator 203 are located outside the passband of the filter 22; the anti-resonant points of the fourth resonator 204 and the fifth resonator 205 are located within the passband of the filter 22, while the resonant points of the fourth resonator 204 and the fifth resonator 205 are located outside the passband of the filter 22; each resonator has a smaller signal impedance near its resonant point and a larger signal impedance near its anti-resonant point.

[0111] During operation, signals within the passband are transmitted sequentially from the input terminal through the first resonator 201, the second resonator 202, and the third resonator 203 to the output terminal, and can then be output outside the filter 22. Signals with frequencies higher than the passband (signals with frequencies near the anti-resonance points of the first resonator 201, the second resonator 202, and the third resonator 203) are prevented from propagating to the output terminal due to the high impedance of the first resonator 201, the second resonator 202, and the third resonator 203. Signals with frequencies lower than the passband (signals with frequencies near the resonant points of the fourth resonator 204 and the fifth resonator 205) are prevented from propagating to the output terminal because the fourth resonator 204 and the fifth resonator 205 have low impedance to them. This achieves high roll-off and high out-of-band rejection. Only signals within the passband can flow from the input terminal to the output terminal of the filter 22, while signals with frequencies higher or lower than the passband will not be output through the output terminal, thus achieving filtering.

[0112] Referring to Figures 5 and 6, the resonator 200 in this embodiment includes a first electrode 220, a piezoelectric layer 230, and a second electrode 240. The first electrode 220 is stacked on a first side of the piezoelectric layer 230, and the second electrode 240 is stacked on a second side of the piezoelectric layer 230. Exemplarily, both the first electrode 220 and the second electrode 240 can be in contact with the piezoelectric layer 230. The first electrode 220 is a reference electrode, which can be provided with a certain reference voltage or grounded. There can be multiple second electrodes 240, which can be spaced apart along a first direction parallel to the piezoelectric layer 230. One of two adjacent second electrodes 240 is used to receive a signal, and the other is used to transmit a signal. Exemplarily, the first electrode 220 can be plate-shaped, and the projection of each second electrode 240 onto the piezoelectric layer 230 is at least partially located within the projection of the first electrode 220 onto the piezoelectric layer 230, so that the first electrode 220 can provide a reference potential to each second electrode 240.

[0113] In some embodiments, the resonator 200 further includes a first busbar 243 and a second busbar 244 disposed on the surface of the piezoelectric layer 230 opposite to the first electrode 220, that is, the first busbar 243, the second busbar 244 and the second electrode 240 are located on the same side of the piezoelectric layer 230; the first busbar 243 and the second busbar 244 are arranged in parallel and spaced apart, and a plurality of second electrodes 240 are disposed between the first busbar 243 and the second busbar 244; the extension directions of the first busbar 243 and the second busbar 244 on the piezoelectric layer 230 can be arranged in parallel, and the extension directions of the first busbar 243 and the second busbar 244 can be parallel to a first direction. The plurality of second electrodes 240 include first sub-electrodes 241 and second sub-electrodes 242, which are alternately arranged along a first direction, i.e., a first second sub-electrode 242 is arranged between two adjacent first sub-electrodes 241; the end of each first sub-electrode 241 near the first busbar 243 is coupled to the first busbar 243, and the end of each first sub-electrode 241 near the second busbar 244 is spaced apart from the second busbar 244; the end of each second sub-electrode 242 near the second busbar 244 is coupled to the second busbar 244, and the end of each second sub-electrode 242 near the first busbar 243 is spaced apart from the first busbar 243. The first busbar 243 can receive input signals and send output signals to each first sub-electrode 241, and the second busbar 244 can receive signals from each second sub-electrode 242 to output signals to the resonator 200.

[0114] In some examples, the projection of the first electrode 220 onto the piezoelectric layer 230 lies between the projections of the first busbar 243 and the second busbar 244 onto the piezoelectric layer 230; the projection of the end of the first sub-electrode 241 facing away from the first busbar 243 onto the piezoelectric layer 230 coincides with the projection of the edge of the first electrode 220 onto the piezoelectric layer 230, and the projection of the end of the second sub-electrode 242 facing away from the second busbar 244 onto the piezoelectric layer 230 coincides with the projection of the edge of the first electrode 220 onto the piezoelectric layer 230. With this configuration, the first electrode 220 is only located within the aperture region K of the resonator, which can improve the resonator's performance. Here, "coincidence" can be understood as the two projections completely overlapping or having a small gap, which can be less than or equal to one-eighth of the sound wave wavelength. Of course, in other examples, the two projections can also have a certain distance between them, which can be less than or equal to one time the sound wave wavelength, also ensuring the resonator's performance.

[0115] In some implementations, the materials of the first sub-electrode 241, the second sub-electrode 242, the first busbar 243, and the second busbar 244 may include copper, aluminum, tungsten, molybdenum, platinum, titanium, chromium, gold, etc., and the material of the first electrode 220 may include molybdenum, tungsten, aluminum, chromium, ruthenium, etc. This application embodiment does not limit the materials of the first electrode 220, the first sub-electrode 241, the second sub-electrode 242, the first busbar 243, and the second busbar 244.

[0116] The resonator 200 in this embodiment can be an acoustic resonator. The main working principle of the acoustic resonator is to use the piezoelectric effect of piezoelectric materials to convert the input signal of the radio wave into mechanical energy using input and output transducers. After processing, the mechanical energy is converted into an electrical signal to filter unnecessary signals and noise and improve the reception quality.

[0117] In some examples, the electric field direction of the resonator 200 is parallel to the thickness direction of the piezoelectric layer 230, and the electric field direction is parallel to the direction 3 shown in Figure 6.

[0118] In this embodiment, the material of the piezoelectric layer 230 may include a piezoelectric material. For example, the piezoelectric material may include a combination of oxygen and zinc; or a combination of nitrogen and aluminum; or a combination of tantalum and lithium; or a combination of niobium and lithium; or a combination of tantalum, niobium, and lithium, etc. Specifically, the combination of oxygen and zinc may include zinc oxide; the combination of nitrogen and aluminum may include aluminum nitride; the combination of niobium and lithium may include lithium niobate, or a mixture of lithium niobate and lithium, etc.; the combination of tantalum and lithium may include lithium tantalate, or a mixture of lithium carbonate and lithium, etc.; the combination of tantalum, niobium, and lithium may include lithium niobate tantalate, or a mixture of lithium niobate tantalate and lithium, etc. This embodiment does not limit the piezoelectric material, as long as it can have a certain piezoelectric effect.

[0119] The resonant modes of resonator 200 are mainly formed by different piezoelectric tensor components under the excitation of electric fields in different directions. The piezoelectric tensor is a third-order tensor with components e. xyz (x = 1, 2, 3; y = 1, 2, 3; z = 1, 2, 3), where x represents the electric field direction, y represents the wave propagation direction, and z represents the polarization direction. 1, 2, and 3 can be the directions of the resonator 200 marked in the coordinate system shown in Figure 6. In the embodiments of this application, the resonator 200 has a piezoelectric tensor component e. 312Under electric field excitation perpendicular to the piezoelectric layer 230, the resulting resonant mode is the dominant mode, which is the zero-order shear horizontal mode (SH0 mode). It can be understood that the polarization direction is the displacement direction of the particles in the piezoelectric material within the electric field. Driven by a radio frequency signal, the piezoelectric material is subjected to an alternating electric field, and correspondingly, the particles in the piezoelectric material reciprocate, thus generating vibration. In some examples, the polarization direction of the piezoelectric material is perpendicular to the first direction and parallel to the piezoelectric layer 230.

[0120] The rotation transformation matrix A in Euler angle representation (α,β,γ) is:

[0121] The piezoelectric tensor components obtained after rotational transformation are: e pqr '=e ijk A ip A jq A kr ;e 312 ' ＝ e ijk A i3 A j1 A k2 Using the Einstein summation convention, by iterating through the piezoelectric tensor components corresponding to each Euler angle (i, j, k ∈ {1, 2, 3}), the maximum value of the piezoelectric tensor component is approximately e. 312 = 2.4534 coulombs per square meter (C / ㎡). And in the piezoelectric tensor component e 312 ≥1.47C / m 2 When the electromechanical coupling coefficient is 1.47C / m², 2C / m², or 2.4534C / m², the resonator 200 has a large electromechanical coupling coefficient K. t 2 That is, the difference between the resonant point (resonant frequency) and the anti-resonant point (anti-resonant frequency) of the resonator 200 is relatively large, which can increase the passband of the filter 22 using the resonator 200, that is, increase the bandwidth of the filter 22 and improve the performance of the corresponding electronic equipment.

[0122] Understandably, k 312 2 =e 312 2 / (ε 33 *c 1212 ), in k 312 2 When the maximum value is obtained, the Euler angle of the corresponding piezoelectric material crystal is obtained. A resonator 200 using a piezoelectric material with this Euler angle has a large electromechanical coupling coefficient K. t 2This can increase the passband of the filter 22 using the resonator 200.

[0123] The resonator provided in this application embodiment utilizes the piezoelectric tensor component e of the resonator. 312 A zero-order horizontal shear mode is generated, which is not affected by the thickness of the piezoelectric layer 230. This avoids the large frequency shift of the resonator caused by the uneven thickness of the piezoelectric layer 230, thus reducing the frequency shift of the resonator.

[0124] In the embodiments of this application, the Euler angles of the piezoelectric material crystal can be of various types, as shown in Table 1; using the Euler angles shown in Table 1 can make the piezoelectric tensor component e 312 The larger value results in the resonator 200 having a larger electromechanical coupling coefficient K. t 2 This can increase the passband of the filter 22 using the resonator 200, thereby improving the performance of the corresponding electronic equipment. It is understood that, based on the Euler angles shown in Table 1, other Euler angles generated by crystal symmetry can also have the same function and effect.

[0125] Table 1

[0126] In some embodiments, the crystal cutting angle and propagation direction of the piezoelectric material are (45°±15°)Y-cut and (45°±15°)X-propagation, or the crystal cutting angle and propagation direction of the piezoelectric material are (45°±15°)Y-cut and (135°±15°)X-propagation; wherein, the X-direction is the first principal axis direction of the piezoelectric material, and the Y-direction is the second principal axis direction of the piezoelectric material. The piezoelectric material with the above-mentioned crystal cutting angle and propagation direction can also make the piezoelectric tensor component e of the resonator... 312 The larger value results in the resonator 200 having a larger electromechanical coupling coefficient K. t 2 This can increase the passband of the filter 22 using the resonator 200, thereby improving the performance of the corresponding electronic equipment.

[0127] In some examples, there is a correspondence between the Euler angles of the piezoelectric crystal and the crystal cutting angle and propagation direction of the piezoelectric material. For example: X-cut, γ-Y propagation, corresponding to Euler angle (90°, 90°, γ); β-Y-cut, γ-X propagation direction, corresponding to Euler angle (0°, β-90°, γ); Z-cut, γ-X propagation direction, corresponding to Euler angle (0°, 0°, γ). Here, the X direction is the first principal axis direction of the piezoelectric material, the Y direction is the second principal axis direction, and the Z direction is the third principal axis direction. It can be understood that the piezoelectric material can include the first principal axis direction, the second principal axis direction, and the third principal axis direction, wherein the first principal axis direction is perpendicular to the second principal axis direction, and the third principal axis direction is perpendicular to the plane containing the first and second principal axis directions.

[0128] In the above implementation, the piezoelectric tensor component e of the resonator 200 312 ≥1.47C / m 2 (e.g., 1.47C / ㎡, 2C / ㎡, 2.4534C / ㎡, etc.); or, the electromechanical coupling coefficient Kt of resonator 200. 2 Setting the value to ≥10% (e.g., 12%, 20%, 40%, 80%, etc.) further improves the electromechanical coupling coefficient Kt of the resonator 200. 2 This further increases the bandwidth of the filter 22 using the resonator 200.

[0129] Please refer to Figures 7 and 8. In the resonator 200 structure shown in Figures 7 and 8, the material of the piezoelectric layer 230 is LN, and the crystal cutting angle and propagation direction of the piezoelectric layer 230 are 45° Y-cut and 45° X-propagation. The Euler angle of the crystal of the piezoelectric layer 230 is (0°, 45°, 45°), and the thickness of the piezoelectric layer 230 is 240 nm. Along the first direction, the width of the second electrode 240 is 360 nm. The thickness of the first electrode 220 and the second electrode 240 can both be 10 nm, and the materials of the first electrode 220 and the second electrode 240 can both include aluminum.

[0130] Figure 8 is a schematic diagram of the vibration of the resonator 200 structure shown in Figure 7. In the figure, "⊙" indicates a direction perpendicular to the paper and outwards. The direction is perpendicular to the paper and inwards. As shown in Figure 8, the vibration direction of resonator 200 is perpendicular to the paper. Figure 9 shows the admittance curve of the structure shown in Figure 7. In the figure, curve abs represents the amplitude of the admittance, and curve Re represents the real part of the admittance. As shown in Figure 9, the resonant frequency fr of this resonator 200 structure is around 5.128 GHz, the anti-resonant frequency fa is around 5.646 GHz, and the electromechanical coupling coefficient Kt is... 2The difference is approximately 20.7%. The significant difference between the resonant frequency fr and the anti-resonant frequency fa results in a larger filter bandwidth using this resonator 200. Furthermore, the resonant frequency of resonator 200 reaches 5 GHz, allowing it to adapt to higher communication frequencies.

[0131] Referring to Figure 10, in some embodiments, two adjacent second electrodes 240 are spaced apart along a first direction, such that a first gap exists between the two adjacent second electrodes 240. A first trench 231 is formed on the piezoelectric layer 230, and the first trench 231 communicates with the first gap. By forming the first trench 231, the piezoelectric tensor component e can be prevented. 112 The SH0 mode is excited, and the first trench 231 can also block the piezoelectric tensor component e. 112 The propagation of the excited SH0 mode reduces the interference of this miscellaneous mode on the main mode.

[0132] Please refer to Figure 11. The two resonators 200 in Figure 11 have roughly the same structure. The piezoelectric layer 230 is made of LN, and its crystal cutting angle and propagation direction are 45° Y-cut and 45° X-propagation. The Euler angles of the crystal in the piezoelectric layer 230 are (0°, 45°, 45°), and its thickness is 200 nm. The first electrode 220 can be made of molybdenum and has a thickness of 30 nm. The second electrode 240 can be made of aluminum and has a thickness of 100 nm. Along the first direction, the distance between adjacent second electrodes 240 is 0.8 μm, and the duty cycle of the second electrode 240 of the resonator 200 is 0.8. Without the first trench 231, the piezoelectric tensor component e... 112 The excited SH0 mode (hybrid mode) is located in the piezoelectric tensor component e 312 The low-frequency side of the resonant point of the excited SH0 mode (main mode) is located, and the difference between the resonant frequency and the anti-resonant frequency of this miscellaneous mode is relatively large.

[0133] Please refer to Figure 12. The two resonators 200 in Figure 12 have roughly the same structure. The piezoelectric layer 230 is made of LN, and its crystal cutting angle and propagation direction are 45° Y-cut and 45° X-propagation. The Euler angles of the crystal in the piezoelectric layer 230 are (0°, 45°, 45°), and its thickness is 400 nm. The first electrode 220 can be made of molybdenum and has a thickness of 30 nm. The second electrode 240 can be made of aluminum and has a thickness of 60 nm. Along the first direction, the distance between adjacent second electrodes 240 is 1 μm. The duty cycle of the second electrode 240 of the resonator 200 is 0.8, and the depth of the first channel is 350 nm. When the first trench 231 is set, the piezoelectric tensor component e... 112 The excited SH0 mode (hybrid mode) is located in the piezoelectric tensor component e 312On the low-frequency side of the resonant point of the excited SH0 mode (dominant mode), the difference between the resonant frequency and the anti-resonant frequency of this hybrid mode is small, and the difference between the admittance of the resonant point and the anti-resonant point of this hybrid mode is also small. Comparing Figures 11 and 12, it can be seen that setting the first trench 231 can prevent the piezoelectric tensor component e... 112 Excite the SH0 mode, and at the same time block the piezoelectric tensor component e. 112 Incentive-driven SHO model propagation.

[0134] Referring to Figure 13, in some implementations, the first trench 231 can penetrate the piezoelectric layer 230 along its thickness direction. This configuration further prevents the piezoelectric tensor component e from penetrating. 112 Incentive SH0 model.

[0135] Referring to Figure 10, in other implementations, the first trench 231 may not penetrate the piezoelectric layer 230 along its thickness direction. For example, the depth of the first trench 231 can be 50%-80% (50%, 70%, 80%, etc.) of the thickness of the piezoelectric layer 230. This configuration can prevent e 112 While stimulating the SH0 mode, avoid damaging the first electrode 220 when fabricating the first trench 231.

[0136] Referring to Figure 14, in the above implementation, the first trench 231 can be disposed only between two adjacent second electrodes 240, that is, the first trench 231 is only located between two adjacent second electrodes 240. Referring to Figure 15, of course, in other implementations, the first trench 231 can also extend from between adjacent first sub-electrodes 241 and second sub-electrodes 242 to positions such as between the first sub-electrode 241 and the second busbar 244, and between the second sub-electrode 242 and the first busbar 243; for example, the first trench 231 is disposed on the remaining piezoelectric layer 230 except for the portion of the piezoelectric layer 230 covered by the first sub-electrode 241, the second sub-electrode 242, the first busbar 243, and the second busbar 244, which can increase the volume of the first trench 231.

[0137] Referring to Figure 16, in this embodiment, the resonator 200 further includes a reflective layer 250 and a dielectric layer 210, which are stacked together. The dielectric layer 210 is located between the reflective layer 250 and the first electrode 220. It is understood that the sound velocity in the reflective layer 250 is different from that in the dielectric layer 210, which can cause sound waves to be reflected at the junction of the reflective layer 250 and the dielectric layer 210. The sound waves can be reflected towards the dielectric layer 210 at the junction of the reflective layer 250 and the dielectric layer 210, thereby preventing sound waves from leaking from the dielectric layer 210.

[0138] In some implementations, the propagation speed of sound waves within the reflective layer 250 can be greater than the propagation speed of sound waves within the dielectric layer 210. The material of the reflective layer 250 includes any one or a combination of silicon carbide, diamond, and boron nitride; the material of the dielectric layer 210 may include silicon oxide, silicon, etc. This application does not limit the materials of the reflective layer 250 and the dielectric layer 210.

[0139] In other implementations, the reflective layer includes at least one first reflective layer and at least one second reflective layer, arranged in an alternating stacked configuration, with the first and second reflective layers having different acoustic impedances. This configuration allows the reflective layer to act as a Bragg reflector, where sound waves can be reflected near the junction surfaces of the first and second reflective layers to prevent sound leakage. For example, one of the at least one first reflective layer may be positioned close to the dielectric layer 210, and correspondingly, the acoustic impedance of the first reflective layer may be higher than that of the dielectric layer 210 and the second reflective layer.

[0140] Referring to Figure 16, in the resonator 200 structure shown in Figure 16, the piezoelectric layer 230 is made of LN, and its crystal cutting angle and propagation direction are 45° Y-cut and 45° X-propagation. The Euler angles of the crystal in the piezoelectric layer 230 are (0°, 45°, 45°), and the thickness of the piezoelectric layer 230 is 400 nm. The first electrode 220 can be made of molybdenum, and its thickness can be 30 nm. The second electrode 240 can be made of aluminum, and its thickness is 100 nm. The distance between adjacent second electrodes 240 is 0.9 μm. The duty cycle of the second electrode 240 of the resonator 200 is 0.7, and the depth of the first trench 231 is 360 nm. Figure 17 is the admittance curve of the structure shown in Figure 16, and Figure 18 is an enlarged view of point A in Figure 17. In the figures, curve abs represents the amplitude of the admittance, and curve Re represents the real part of the admittance. As shown in Figures 17 and 18, the resonant frequency fr of the resonator 200 structure is around 3.12 GHz, the anti-resonant frequency fa is around 3.325 GHz, and the electromechanical coupling coefficient Kt2 is approximately 14.3%.

[0141] Referring again to Figure 16, in this embodiment, the resonant frequency f of the resonator 200 satisfies:

[0142] Where f is the resonant frequency of the resonator 200 (the frequency corresponding to the resonant point), and V SHLet P be the shear wave velocity of the piezoelectric material, P be the distance between the center lines of adjacent second electrodes 240, and MR be the duty cycle of the second electrode 240 of the resonator 200. From the above formula, it can be seen that the resonant frequency is directly proportional to the reciprocal of the duty cycle, i.e., the resonant frequency and the duty cycle are inversely proportional. The resonant frequency can be adjusted by changing the duty cycle. When the material of the piezoelectric layer 230 is the same as P, decreasing the duty cycle can increase the resonant frequency of the resonator 200, thereby allowing the filter 22 using the resonator 200 to be suitable for higher frequency signals, such as the sub-6GHz band.

[0143] On the other hand, duty cycle Where p is the distance between the center lines of adjacent second electrodes 240, and d is the width of the second electrode 240 along the first direction; in the embodiments of this application, the duty cycle of the second electrode 240 of the resonator 200 is relatively small. When P is the same, the width d of the second electrode 240 can be appropriately reduced to avoid the gap between adjacent second electrodes 240 being too small (for example, the gap should not be less than 0.3 μm, as the photolithography difficulty is greater when the gap is less than 0.3 μm), thereby reducing the fabrication difficulty of the resonator 200 (such as reducing the photolithography difficulty).

[0144] For example, the duty cycle of the second electrode 240 of the resonator 200 is 0.2-0.8. This configuration allows the resonator to have a larger resonant frequency to meet the requirements of high-frequency applications.

[0145] In some embodiments, the width of the second electrode along the first direction is 300nm-400nm (e.g., 300nm, 350nm, 400nm, etc.). This setting ensures that the distance between adjacent second electrodes is not too large or too small when the duty cycle is small, thus facilitating the fabrication of the resonator. Alternatively, the distance between adjacent second electrodes can be 0.4μm-1.2μm (0.4μm, 1μm, 1.2μm, etc.). This setting also ensures that the width of the second electrode along the first direction is not too large or too small when the duty cycle is small, thus facilitating the fabrication of the resonator.

[0146] In some embodiments, the thickness of the piezoelectric layer 230 is 180nm-600nm (e.g., 180nm, 350nm, 600nm, etc.). This setting ensures that the thickness of the piezoelectric layer 230 is appropriate, so as to ensure that the volume of the resonator is not too large or too small.

[0147] In some embodiments, the thickness of the second electrode 240 is 8nm-120nm (8nm, 50nm, 120nm, etc.). This setting makes the thickness of the second electrode 240 suitable and facilitates its fabrication.

[0148] In the resonator 200 structure shown in Figure 16, the piezoelectric layer 230 is made of LN, and its crystal cutting angle and propagation direction are 45° Y-cut and 45° X-propagation. The Euler angles of the crystal in the piezoelectric layer 230 are (0°, 45°, 45°), and its thickness is 267 nm. The first electrode 220 can be made of molybdenum, and its thickness can be 20 nm. The second electrode 240 can be made of aluminum, and its thickness is 67 nm. The distance between adjacent second electrodes 240 is 0.6 μm. The duty cycle of the second electrode 240 of the resonator 200 is 0.7, and the depth of the first trench 231 is 240 nm. Figure 19 shows the admittance curve of the structure shown in Figure 16 under the above parameters, and Figure 20 is an enlarged view of point B in Figure 19. In the figures, curve abs represents the magnitude of the admittance, and curve Re represents the real part of the admittance. As shown in Figures 19 and 20, the resonant frequency fr of the resonator 200 structure is around 4.68 GHz, the anti-resonant frequency fa is around 4.95 GHz, and the electromechanical coupling coefficient Kt is... 2 Approximately 14.2%.

[0149] In the resonator 200 structure shown in Figure 16, the piezoelectric layer 230 is made of LN, and its crystal cutting angle and propagation direction are 45° Y-cut and 45° X-propagation. The Euler angles of the crystal in the piezoelectric layer 230 are (0°, 45°, 45°), and its thickness is 240 nm. The first electrode 220 can be made of molybdenum, and its thickness can be 18 nm. The second electrode 240 can be made of aluminum, and its thickness is 60 nm. The distance between adjacent second electrodes 240 is 0.54 μm. The duty cycle of the second electrode 240 of the resonator 200 is 0.7, and the depth of the first trench 231 is 216 nm. Figure 21 is the admittance curve of the structure shown in Figure 16 under the above parameters, and Figure 22 is an enlarged view of point C in Figure 21. In the figures, curve abs represents the magnitude of the admittance, and curve Re represents the real part of the admittance. As shown in Figures 21 and 22, the resonant frequency fr of the resonator 200 structure is around 5.205 GHz, the anti-resonant frequency fa is around 5.54 GHz, and the electromechanical coupling coefficient Kt is... 2 Approximately 14.1%.

[0150] As shown in Figures 20 and 22, the resonator 200 provided in this embodiment is applicable to the 5GHz-6GHz frequency band, and the operating frequency band of the resonator 200 is relatively high. In addition, there are fewer parasitic clutter modes between the resonant point and the anti-resonant point, near the resonant point, and near the anti-resonant point of the resonator 200.

[0151] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A resonator, characterized in that, include: A first electrode, a piezoelectric layer, and a plurality of second electrodes, wherein the first electrode is disposed on a first side of the piezoelectric layer, and the plurality of second electrodes are disposed on a second side of the piezoelectric layer, and the plurality of second electrodes are spaced apart along a first direction parallel to the piezoelectric layer; The piezoelectric layer includes a piezoelectric material, the polarization direction of which is perpendicular to the first direction and parallel to the piezoelectric layer; The Euler angles of the crystal of the piezoelectric material are (0°±15°, 45°±15°, 45°±15°), or the cutting angle and propagation direction of the crystal of the piezoelectric material are (45°±15°)Y-cut and (45°±15°)X-propagation. Alternatively, the Euler angles of the piezoelectric material crystal are (0°±15°, 45°±15°, 135°±15°), or the cutting angle and propagation direction of the piezoelectric material crystal are (45°±15°) Y-cut and (135°±15°) X-propagation. Wherein, the X direction is the first principal axis direction of the piezoelectric material, and the Y direction is the second principal axis direction of the piezoelectric material; Alternatively, the Euler angles of the crystal of the piezoelectric material are (60°±15°, 135°±15°, 45°±15°); Alternatively, the Euler angles of the crystal of the piezoelectric material are (60°±15°, 135°±15°, 135°±15°); Alternatively, the Euler angles of the crystal of the piezoelectric material are (120°±15°, 45°±15°, 45°±15°); Alternatively, the Euler angles of the crystal of the piezoelectric material are (120°±15°, 45°±15°, 135°±15°); Alternatively, the Euler angles of the crystal of the piezoelectric material are (180°±15°, 135°±15°, 45°±15°); Alternatively, the Euler angles of the crystal of the piezoelectric material are (180°±15°, 135°±15°, 135°±15°).

2. The resonator according to claim 1, characterized in that, The piezoelectric tensor component e of the resonator 312 ≥1.47C / m 2 Alternatively, the electromechanical coupling coefficient Kt of the resonator 2 ≥10%.

3. The resonator according to claim 1 or 2, characterized in that, There is a first gap between two adjacent second electrodes, and a first trench is provided on the piezoelectric layer, the first trench being connected to the first gap.

4. The resonator according to claim 3, characterized in that, The first trench penetrates the piezoelectric layer.

5. The resonator according to any one of claims 1-4, characterized in that, The resonator further includes a reflective layer and a dielectric layer. The dielectric layer is disposed on the side of the first electrode away from the piezoelectric layer, and the reflective layer is disposed on the side of the dielectric layer away from the piezoelectric layer.

6. The resonator according to claim 5, characterized in that, The material of the reflective layer includes silicon carbide; Alternatively, the reflective layer includes at least one first reflective layer and at least one second reflective layer, wherein the first reflective layer and the second reflective layer are alternately stacked, and the first reflective layer and the second reflective layer have different acoustic impedances.

7. The resonator according to any one of claims 1-6, characterized in that, The materials of the piezoelectric layer include a combination of oxygen and zinc; or a combination of nitrogen and aluminum; or a combination of tantalum and lithium; or a combination of niobium and lithium; or a combination of tantalum, niobium and lithium.

8. The resonator according to any one of claims 1-7, characterized in that, The resonator satisfies: Where f is the resonant frequency of the resonator, V SH denoted as the shear wave velocity of the piezoelectric material, P is the distance between the center lines of adjacent second electrodes, and MR is the duty cycle of the second electrode of the resonator.

9. The resonator according to claim 8, characterized in that, The duty cycle of the second electrode of the resonator is 0.2-0.

8.

10. The resonator according to any one of claims 1-9, characterized in that, The resonator further includes a first busbar and a second busbar, the first busbar, the second busbar and the second electrode are located on the same side of the piezoelectric layer, the first busbar and the second busbar are arranged in parallel and spaced apart, and the plurality of second electrodes are disposed between the first busbar and the second busbar; The plurality of second electrodes includes a plurality of first sub-electrodes and a plurality of second sub-electrodes, which are alternately arranged along the first direction. Each first sub-electrode is coupled to the first busbar, and each second sub-electrode is coupled to the second busbar.

11. The resonator according to claim 10, characterized in that, The projection of the first electrode on the piezoelectric layer is located between the projections of the first busbar and the second busbar on the piezoelectric layer; the projection of the end of the first sub-electrode away from the first busbar on the piezoelectric layer coincides with the projection of the edge of the first electrode on the piezoelectric layer, and the projection of the end of the second sub-electrode away from the second busbar on the piezoelectric layer coincides with the projection of the edge of the first electrode on the piezoelectric layer.

12. A resonator, characterized in that, include: A first electrode, a piezoelectric layer, and a plurality of second electrodes, wherein the first electrode is disposed on a first side of the piezoelectric layer, and the plurality of second electrodes are disposed on a second side of the piezoelectric layer, and the plurality of second electrodes are spaced apart along a first direction parallel to the piezoelectric layer; The piezoelectric tensor component e of the resonator 312 ≥1.47C / m 2 .

13. The resonator according to claim 12, characterized in that, There is a first gap between two adjacent second electrodes, and a first trench is provided on the piezoelectric layer, the first trench being connected to the first gap.

14. The resonator according to claim 13, characterized in that, The first trench penetrates the piezoelectric layer.

15. The resonator according to any one of claims 12-14, characterized in that, The resonator further includes a reflective layer and a dielectric layer. The dielectric layer is disposed on the side of the first electrode away from the piezoelectric layer, and the reflective layer is disposed on the side of the dielectric layer away from the piezoelectric layer.

16. The resonator according to any one of claims 12-15, characterized in that, The resonator satisfies: Where f is the resonant frequency of the resonator, V SH denoted as shear wave velocity, P as the distance between the center lines of adjacent second electrodes, and MR as the duty cycle of the second electrode of the resonator.

17. The resonator according to claim 16, characterized in that, The duty cycle of the second electrode of the resonator is 0.2-0.

8.

18. A filter, characterized in that, include: A plurality of resonators, at least one of which is a resonator according to any one of claims 1-17, wherein at least two of the plurality of resonators are connected in series or in parallel.

19. A communication chip, characterized in that, include: A radio frequency (RF) front-end circuit, the RF front-end circuit including a power amplifier and / or a low-noise amplifier, and a filter as described in claim 18, wherein the power amplifier and / or the low-noise amplifier are coupled to the filter.

20. An electronic device, characterized in that, include: The antenna and the communication chip of claim 19, wherein the communication chip is coupled to the antenna.

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