Transverse excitation bulk acoustic wave resonator and filter

Abstract

The invention provides a transverse excitation bulk acoustic wave resonator and a filter. The resonator comprises a piezoelectric substrate; the first electrode group and the second electrode group are arranged in the piezoelectric substrate at intervals, the first electrode group and the second electrode group are configured to penetrate through the piezoelectric substrate in the thickness direction of the piezoelectric substrate, the first electrode group comprises at least two first sub-electrodes which are arranged at intervals, and the second electrode group comprises at least two second sub-electrodes which are arranged at intervals; different electrode groups are configured to apply different potentials so as to form active areas among the different electrode groups, and different sub-electrodes in the same electrode group are configured to apply the same potential so as to form passive areas among different sub-electrodes in the same electrode group. Uniform electric fields are distributed in the active area, so that high-phase-velocity sound wave transmission and higher electromechanical coupling can be realized; various functional structures can be arranged in the passive area, so that the electrical performance, mechanical performance or / and thermal performance of the resonator are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and in particular to a transversely excited bulk acoustic wave resonator and a filter. Background Art

[0002] Piezoelectric resonators usually include a piezoelectric substrate and an interdigital transducer (IDT) formed by conductive electrode fingers. Due to the piezoelectric effect, surface acoustic waves (SAW) are generated and propagated in the electrode grating as the main mode. The resonant characteristics of surface acoustic wave resonators are widely used in various acoustic devices. Radio frequency (RF) filters based on surface acoustic wave resonators are often used in wireless communication equipment. The new sub-6 GHz band requires resonators to have ultra-wide bandwidth, low insertion loss and high Q value at the same time. Traditional resonators cannot meet the requirements of the new sub-6 GHz band for frequency range, loss, size reduction and power endurance, as shown in Table 1.

[0003] Table 1

[0004]

[0005] Based on lithium tantalate substrate (LiTaO 3 , LN) or lithium niobate substrate (LiNbO 3 , LT) as an example, generally speaking, the approximate width required for the interdigital transducer (IDT) is between 200nm and 350nm. When the recent resonator process resolution is about 0.5μm, the reliability of the interdigital transducer (IDT) structure less than 500nm is difficult to guarantee.

[0006] Therefore, it is necessary to provide a filter design that can meet the performance requirements and stability requirements of an ultra-wideband (UHB) filter.

[0007] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a transversely excited bulk acoustic wave resonator and a filter to solve the problem that the filter in the prior art is difficult to meet the performance and stability requirements of an ultra-wideband (UHB) filter.

[0009] To achieve the above-mentioned purpose and other related purposes, the present invention provides a laterally excited bulk acoustic wave resonator, the resonator comprising: a piezoelectric substrate; a first electrode group and a second electrode group, which are arranged at intervals in the piezoelectric substrate, the first electrode group and the second electrode group are configured to penetrate the piezoelectric substrate along the thickness direction of the piezoelectric substrate, the first electrode group comprises at least two first sub-electrodes arranged at intervals, the second electrode group comprises at least two second sub-electrodes arranged at intervals, different electrode groups are configured to apply different potentials to form active regions between different electrode groups, and different sub-electrodes in the same electrode group are configured to apply the same potential to form passive regions between different sub-electrodes in the same electrode group.

[0010] Optionally, the piezoelectric substrate includes one of lithium tantalate, lithium niobate and aluminum nitride.

[0011] Optionally, the thickness d of the piezoelectric substrate is in the range of 0.09λ≤d≤0.13λ, wherein λ is the wavelength of the bulk acoustic wave.

[0012] Optionally, the width of the passive region is 0.005λ to 0.05λ, wherein λ is the wavelength of the bulk acoustic wave.

[0013] Optionally, the material of the first electrode group and the second electrode group includes one of aluminum and copper.

[0014] Optionally, the duty cycle range of the first electrode group and the second electrode group is set to be between 0.25 and 0.3.

[0015] Optionally, the width of the first sub-electrode and the second sub-electrode is 10 nanometers to 100 nanometers, or the width of the first sub-electrode and the second sub-electrode is 0.01 times to 0.05 times the wavelength of the bulk acoustic wave.

[0016] Optionally, a support column is further included, and the support column is fixedly connected to the passive area.

[0017] Optionally, the width of the support column is 0.2 to 1 times the width of the passive region.

[0018] Optionally, the material of the support column includes SiO 2 , porous silicone resin, Al 2 O 3 、AlN、Ta 2 O 5 , one of Al, Cu, Ti, Si and Pt.

[0019] Optionally, the support column includes a first end and a second end, the first end is fixedly connected to the passive area, and the second end is connected to the supporting base, and an isolation layer is also arranged between the supporting base and the support column, and the isolation layer includes a stacked structure composed of one or more of a diamond-like film, a silicon dioxide film and an aluminum film.

[0020] Optionally, the cross-sectional shapes of the first sub-electrode and the second sub-electrode include one of a rectangle, a triangle, a trapezoid, a step, a dumbbell and an arc.

[0021] Optionally, the first sub-electrode and the second sub-electrode penetrate the piezoelectric substrate vertically or penetrate the piezoelectric substrate at an angle.

[0022] Optionally, the first sub-electrode and the second sub-electrode are phononic crystal materials with a periodic structure or a semi-periodic structure, or are metamaterials with a periodic structure or a semi-periodic structure.

[0023] Optionally, the piezoelectric substrate in the inactive region is partially removed to form a cavity.

[0024] Optionally, the piezoelectric substrate in the passive area is partially or completely removed to form a filling cavity, and the filling cavity is filled with a functional structure, and the functional structure is used to improve one or more of the electrical performance, mechanical performance or thermal performance of the resonator.

[0025] Optionally, the material of the functional structure includes one of a phononic crystal and a metamaterial.

[0026] Optionally, the functional structure comprises a Bragg reflector structure.

[0027] Optionally, a functional structure is formed inside the active region or / and on the surface of the active region, and the functional structure is used to improve one or more of the electrical properties, mechanical properties or thermal properties of the resonator.

[0028] The present invention also provides a filter, comprising at least one transversely excited bulk acoustic wave resonator as described in any one of the above schemes.

[0029] As described above, the transversely excited bulk acoustic wave resonator and filter of the present invention have the following beneficial effects:

[0030] The present invention sets a first electrode group and a second electrode group in a piezoelectric substrate, the first electrode group and the second electrode group are configured to penetrate the piezoelectric substrate along the thickness direction of the piezoelectric substrate, the first electrode group includes at least two first sub-electrodes arranged at intervals, the second electrode group includes at least two second sub-electrodes arranged at intervals, different electrode groups are configured to apply different potentials to form active regions between different electrode groups, and different sub-electrodes in the same electrode group are configured to apply the same potential to form passive regions between different sub-electrodes in the same electrode group. On the one hand, the present invention has a uniform electric field distributed in the active region, which can realize a transverse excitation bulk acoustic wave with a high phase velocity and achieve extremely high piezoelectric coupling; on the other hand, various functional structures can be set in the passive region to improve the electrical performance, mechanical performance or / and thermal performance of the resonator, and the piezoelectric strain of the passive region is low when an electric field is applied, so a support column can also be set in the passive region. The support column is set in the passive region, which has a low bulk acoustic wave loss, and while obtaining the support of the resonator, it is ensured that the resonator has a high Q value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application.

[0032] Figure 1 Shown is a schematic diagram of the structure of a traditional transversely excited bulk acoustic wave (XBAR) resonator.

[0033] Figure 2 Display as Figure 1 Impedance parameter curve of the traditional XBAR resonator with a structure.

[0034] Figure 3 The XBAR resonator structure and its impedance parameter curve are shown as an interdigitated transistor structure (IDT) with grooves.

[0035] Figure 4 It is a schematic diagram of the three-dimensional structure of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0036] Figure 5 It is a schematic diagram of the cross-sectional structure of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0037] Figure 6 It is a schematic diagram showing the electric field distribution of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0038] Figure 7 and Figure 8FIG. 4 shows the electric field distribution of the transversely excited bulk acoustic wave resonator in the A1 high-order mode according to an embodiment of the present invention.

[0039] Fig. 9 and Fig.10 They respectively show the displacement distribution and the stored mechanical energy spectrum of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention in the A1 high-order mode.

[0040] Fig.11 and 12 Impedance parameter curves of two different electrode materials (aluminum and copper) used in the transversely excited bulk acoustic wave resonator according to the embodiment of the present invention are shown respectively.

[0041] Fig.13 The graph shows the relationship between the phase velocity and electromechanical coupling coefficient (k2) of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention and different electrode materials (aluminum and copper) at different piezoelectric substrate thicknesses.

[0042] Fig.14 The graph shows the function of the piezoelectric substrate thickness and sensitivity of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0043] Fig.15 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to the embodiment of the present invention and the electrode duty cycle.

[0044] Fig.16 The graph shows the relationship between the electrode width, phase velocity and electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0045] Fig.17 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention and the wavelength.

[0046] Fig.18 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention and the wave number.

[0047] Fig.19 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention and the width of the passive region.

[0048] Fig. 20 Shown is a spurious pattern of a transversely excited BAW resonator according to an embodiment of the present invention when the width of the passive region is extended to 100 nm.

[0049] Fig.21 Shown is a spurious pattern of a transversely excited BAW resonator according to an embodiment of the present invention when the width of the passive region is extended to 150 nm.

[0050] Fig. 22 It is a schematic diagram of the three-dimensional structure of the laterally excited bulk acoustic wave resonator provided with a supporting substrate and supporting pillars according to an embodiment of the present invention.

[0051] Fig.23 It is a schematic cross-sectional structure diagram showing the arrangement of a supporting substrate and supporting pillars for a laterally excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0052] Fig.24 The lateral excitation bulk acoustic wave resonator of the embodiment of the present invention is shown in FIG. 2 ) Q value curve at .

[0053] Fig.25 The lateral excited bulk acoustic wave resonator of the embodiment of the present invention is shown in FIG. 2 ) width.

[0054] Fig.26 The graph shows the relationship between the transversely excited bulk acoustic wave resonator Q value and the resonator Q value under different isolation layer materials and thicknesses according to an embodiment of the present invention.

[0055] Figure 27 to Figure 29 Schematic diagram showing different sub-electrode shapes of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention.

[0056] Fig.30 It is a schematic structural diagram showing that a sub-electrode of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention is tilted at an angle and penetrates through a piezoelectric substrate.

[0057] Fig.31 The diagram shows a schematic structure of a phononic crystal material in which the sub-electrodes of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention are arranged to have a periodic structure or a semi-periodic structure.

[0058] Fig.32 The schematic diagram shows a structure in which a piezoelectric substrate in a passive region of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention is partially removed to form a cavity.

[0059] Fig.33 and Fig.34 Schematic diagrams showing structures in which a piezoelectric substrate in a passive region of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention is partially or completely removed to form a filling cavity, and the filling cavity is filled with a functional structure.

[0060] Fig.35 and Fig.36 Schematic diagrams showing structures in which functional structures are arranged inside or on the upper and lower surfaces of the active region of the transversely excited bulk acoustic wave resonator according to embodiments of the present invention.

[0061] Component number description

[0062] 10 Piezoelectric Substrate

[0063] 11. First electrode group

[0064] 111, 112 first sub-electrode

[0065] 12. Second electrode group

[0066] 121, 122 second sub-electrode

[0067] 13 Active area

[0068] 14 Passive Area

[0069] 15 Electric Field

[0070] 20 Support columns

[0071] 30 Support substrate

[0072] 301 Isolation Layer

[0073] 601 Cavity

[0074] 602, 603, 604, 605 Functional structures DETAILED DESCRIPTION

[0075] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0076] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

[0077] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0078] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0079] For ease of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0080] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0081] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0082] LiNbO based on Z-cut 3 The structure of a conventional XBAR resonator on a piezoelectric substrate is shown in Figure 1 As shown, the conductive electrodes of the structure are arranged above the surface of the piezoelectric substrate at intervals. Figure 1 The resonator has a structure in which the bulk acoustic wave propagates in the piezoelectric substrate between two conductive electrodes. The bulk acoustic wave of this structure has lateral leakage loss, which leads to a decrease in the Q value of the low resonator. Figure 1 Structural optimization of the resonator, such as optimization of substrate material and thickness parameters, Figure 1 The piezoelectric coupling rate of the resonator can reach a relatively high 30-35%. Figure 1 The conductive electrodes are arranged on the surface of the piezoelectric substrate, which will inevitably cause the electric field in the piezoelectric substrate to be uneven in the lateral distribution, thereby limiting the improvement of its piezoelectric coupling efficiency. The impedance parameters of the traditional XBAR resonator are shown in Figure 2.

[0083] In order to increase the coupling efficiency of the resonator, an interdigitated electrode structure (IDT) with grooves can also be used. The interdigitated electrode structure is embedded in the surface of the piezoelectric substrate, which can improve the uniformity of the electric field to a certain extent. The interdigitated electrode structure and the corresponding impedance parameters are as follows: Figure 3As shown. However, with the increase of the electromechanical coupling coefficient (k2), the scattering loss and attenuation of the periodic acoustic impedance region formed by the interdigitated electrodes increase, which will lead to a decrease in the resonator Q value. Moreover, the electrodes of this structure are still non-uniform in the thickness direction of the piezoelectric substrate, which will also limit the improvement of the piezoelectric coupling efficiency of the resonator.

[0084] Example 1

[0085] like Figure 4-5 As shown, this embodiment provides a transversely excited bulk acoustic wave resonator, the resonator comprising: a piezoelectric substrate 10; a first electrode group 11 and a second electrode group 12, which are arranged in the piezoelectric substrate 10 at intervals, the first electrode group 11 and the second electrode group 12 are configured to penetrate the piezoelectric substrate 10 along the thickness direction of the piezoelectric substrate 10, the first electrode group 11 comprises at least two first sub-electrodes 111 and 112 arranged at intervals, the second electrode group 12 comprises at least two second sub-electrodes 121 and 122 arranged at intervals, different electrode groups are configured to apply different potentials to form an active region 13 between different electrode groups, and different sub-electrodes in the same electrode group are configured to apply the same potential to form an inactive region 14 between different sub-electrodes in the same electrode group. In this embodiment, the cross-sectional shape of the first sub-electrodes 111, 112 and the second sub-electrodes 121 and 122 can be, for example, a rectangle, and the first sub-electrodes 111, 112 and the second sub-electrodes 121 and 122 vertically penetrate the piezoelectric substrate 10.

[0086] The first electrode group 11 and the second electrode group 12 are configured to penetrate the piezoelectric substrate 10 along the thickness direction of the piezoelectric substrate 10, and a uniform electric field 15 can be generated in the active region 13 to significantly increase the electromechanical coupling coefficient (k2) of the resonator. However, due to the different acoustic impedances of the electrode material and the piezoelectric substrate, the performance of the resonator will be affected to a certain extent. In the present application, the electrode group is configured as at least two spaced sub-electrodes to form a passive region 14 between the sub-electrodes. By optimizing the parameters and structure of the passive region 14, the reduction in resonator performance caused by the electrode group penetrating the piezoelectric substrate can be compensated, thereby realizing a resonator with a higher phase velocity and a higher piezoelectric coupling efficiency. Figure 6 FIG. 1 is a schematic diagram showing the electric field distribution of a transversely excited bulk acoustic wave resonator according to an embodiment of the present invention. Figure 6As shown, when the first electrode group 11 and the second electrode group 12 of the above-mentioned transversely excited bulk acoustic wave resonator apply corresponding electric potentials, the active region 13 between the first electrode group 11 and the second electrode group 12 will generate a uniform electric field 15, and since different sub-electrodes in the same electrode group are configured to apply the same electric potential, no electric field is actually generated in the passive region 14. Since the uniformity of the electric field distribution in the active region 13 between adjacent electrode groups is greatly improved, the resonator structure of this example can significantly increase the electromechanical coupling coefficient (k2) of the resonator, so that this type of resonator can be effectively applied to filters with an ultra-wide frequency range (UHB). At the same time, since the actual electric field in the passive region 14 is zero or close to zero, the passive region 14 can be configured as any acoustic material (piezoelectric material or non-piezoelectric material) or acoustic structure (structure for acoustic matching, phononic crystal structure, etc.), thereby greatly improving the application range of the resonator and providing a structural basis for improving various aspects of the performance of the resonator. In this example, by optimizing the parameters and structure of the passive region 14, a resonator with a higher phase velocity and a higher piezoelectric coupling efficiency can be realized.

[0087] In a specific example, a finite element simulation is performed on the above-mentioned transversely excited bulk acoustic wave resonator, and the simulation results are as follows: Figure 7 to Figure 10 As shown, Figure 7 and Figure 8 The figure shows the electric field distribution of the transversely excited bulk acoustic wave resonator in the A1 high-order mode according to an embodiment of the present invention. Fig. 9 and Fig.10 The displacement distribution and stored mechanical energy spectrum of the transversely excited BAW resonator in the A1 high-order mode of the embodiment of the present invention are shown respectively. In the simulation process, the specific design parameters are as follows: the piezoelectric substrate 10 is selected as a Z-cut lithium niobate piezoelectric substrate 10, the thickness is 0.1 times the BAW wavelength, the BAW wavelength L = 4μm, the electrode duty cycle DF = 0.3, the electrode material is selected as Al, the sub-electrode width is 50nm, and the electrode duty cycle can be referred to Figure 6 , the duty cycle of the electrode DF = S / (L+S). The electric field distribution in the A1 high-order mode is as follows Figure 7 As shown, it can be seen that the electric field is uniformly distributed in the path between the electrode groups, that is, uniformly distributed in the active area 13, while the electric field is concentrated in the central area of ​​the electrode, as shown in FIG. Figure 8 shown. Fig. 9 and Fig.10 The displacement distribution and stored mechanical energy spectrum are shown respectively. Fig. 9 and Fig.10 It can be clearly seen from the structure that less mechanical energy is distributed in the gap between the separated sub-electrodes, which makes it possible to use the passive area 14 for mechanical support or acoustic matching.

[0088] In one embodiment, the piezoelectric substrate 10 includes one of lithium tantalate, lithium niobate and aluminum nitride. In one embodiment, the piezoelectric substrate 10 is preferably a piezoelectric material with a thickness less than a bulk acoustic wave wavelength λ, so as to improve the uniformity of the electric field between the first electrode group 11 and the second electrode group 12, thereby improving the piezoelectric coupling efficiency.

[0089] In one embodiment, the thickness d of the piezoelectric substrate 10 is in the range of 0.09λ≤d≤0.13λ, where λ is the wavelength of the bulk acoustic wave. In one embodiment, the material of the first electrode group 11 and the second electrode group 12 includes one of aluminum and copper. Fig.11 and 12 1 and 2 show impedance parameter curves of two different electrode materials (aluminum and copper) used in the transversely excited bulk acoustic wave resonator according to an embodiment of the present invention, respectively. Fig.13 The graph shows the relationship between the phase velocity and electromechanical coupling coefficient (k2) of the transversely excited bulk acoustic wave resonator according to the embodiment of the present invention and different electrode materials (aluminum and copper) at different thicknesses of the piezoelectric substrate 10. Specifically, Figure 11 to Figure 13 As shown in FIG. 1 , since a thin film piezoelectric substrate 10 is used, the acoustic wave velocity and the resonance frequency of the resonator are mainly affected by the thickness of the piezoelectric substrate 10. The theoretical results of the relationship between the acoustic wave velocity and the piezoelectric coupling efficiency and the thickness of the piezoelectric substrate 10 are shown in FIG. Fig.11 and Fig.12 shown. Fig.11 and 12 The impedance parameters of two different electrode materials (aluminum and copper) were compared. From the results, the impedance ratio of the copper electrode is slightly higher than that of the aluminum electrode, and has different spurious spectrum characteristics, while the electrode material has no significant effect on the acoustic wave velocity, such as Fig.13 As shown. Fig.13 It can be seen that the relationship between the thickness of the piezoelectric substrate 10 and the electromechanical coupling coefficient has a certain relationship with the electrode material, while the phase velocity remains basically unchanged. However, for the two electrode materials, in the optimal piezoelectric substrate 10 thickness range (0.09λ≤d≤0.13λ), the maximum electromechanical coupling coefficients (k2) of the two are basically the same.

[0090] Fig.14 The function curve of the thickness and sensitivity of the piezoelectric substrate 10 of the transversely excited bulk acoustic wave resonator according to the embodiment of the present invention is shown by Fig.14 It can be seen that the sensitivity of the resonator in this example can reach 7 to 12 MHz / nm in the optimal thickness range of the piezoelectric substrate 10 (0.09λ≤d≤0.13λ). Moreover, for a piezoelectric substrate 10 with a smaller thickness, the sensitivity of the resonator will be higher, such as when the thickness is 0.07λ, the sensitivity can be as high as 20 MHz / nm.

[0091] In one embodiment, the duty cycle of the first electrode group 11 and the second electrode group 12 is set to be between 0.25 and 0.3. Fig.15 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator and the electrode duty cycle according to the embodiment of the present invention. Fig.16 The graph shows the relationship between the electrode width, phase velocity and electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to the embodiment of the present invention. Fig.15 As shown, the optimal duty cycle range of Al and Cu electrode materials is within 0.25-0.3. When the duty cycle increases, which means that the length of the active region 13 increases, both Al and Cu electrode materials show a similar decrease in acoustic wave velocity, and when the Al electrode is used, its electromechanical coupling coefficient (k2) is more sensitive than that of the Cu electrode. For the Al electrode, the maximum electromechanical coupling coefficient (k2) is reached when the duty cycle DF = 0.3, and for the Cu electrode, its maximum electromechanical coupling coefficient (k2) is higher, as shown in FIG. Fig.15 As shown. Fig.16 As shown, when the electrode width increases, the electromechanical coupling coefficient (k2) and the phase velocity both decrease, so the narrower the electrode, the better. In one embodiment, in order to ensure the conductivity of the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 and reduce the difficulty of processing, as well as reduce energy leakage, the width of the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 can be set to 10 nanometers-100 nanometers, or, the width of the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 can be set to 0.01 times-0.05 times the wavelength of the bulk acoustic wave, so that the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 can simultaneously meet the requirements of reducing the difficulty of processing, the requirements of sufficient conductivity and the requirements of reducing energy leakage. Preferably, the width of the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 is selected to be less than or equal to 50nm.

[0092] The width of the passive region can be set to 0.005λ to 0.05λ, where λ is the wavelength of the bulk acoustic wave, so as to reduce the stray of the device while ensuring that the passive region has sufficient width. In one embodiment, the width of the passive region 14 is less than or equal to 150nm. Fig.17 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator and the wavelength of the embodiment of the present invention. Fig.18 The graph shows the relationship between the phase velocity and electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator and the wave number in the embodiment of the present invention. Fig.17As shown in FIG. 1 , since the mechanical properties and resonance frequency of the resonator mainly depend on the thickness of the piezoelectric substrate 10, it can be assumed that the phase velocity of the Cu electrode and the Al electrode increases linearly with the wavelength and the dispersion is low. For the piezoelectric substrate 10 with a thickness of 400 nm, when the wavelength is in the range of 3 μm to 7 μm, the electromechanical coupling coefficient (k2) exhibits dispersion characteristics and reaches a maximum value, while from Fig.17 It can be seen that the dispersion properties of Al electrode and Cu electrode materials are slightly different. For low-density electrode materials such as Al electrode, it has a smaller deviation of electromechanical coupling coefficient with wavelength. Fig.17 It can be seen that both lower wavelength and higher wavelength will lead to a decrease in phase velocity and coupling coefficient. Therefore, the resonator in this example preferably uses an optimal wavelength range of 3 μm to 7 μm.

[0093] Fig.19 The graph shows the relationship between the phase velocity and the electromechanical coupling coefficient of the transversely excited bulk acoustic wave resonator according to the embodiment of the present invention and the width of the passive region 14. Fig. 20 The spurious spectrum of the transversely excited bulk acoustic wave resonator of the embodiment of the present invention when the width of the passive region 14 is extended to 100 nm is shown. Fig.21 The spurious spectrum of the transversely excited bulk acoustic wave resonator of the embodiment of the present invention is shown when the width of the passive region 14 is extended to 150 nm. Figure 19 to Figure 21 From the results, when the width of the passive region 14 extends to 100nm, the phase velocity and the electromechanical coupling coefficient (k2) are not significantly affected, and the electromechanical coupling coefficient (k2) may increase slightly due to changes in the acoustic properties (physical dimensions) of the transmission line, and the phase velocity decreases slightly. When the width of the passive region 14 reaches more than 150nm, strong spurs appear between fs (series resonance) and fp (parallel resonance). Therefore, the width of the passive region 14 of the resonator of this example is less than or equal to 150nm, preferably less than or equal to 100nm, which can ensure that the resonator has a higher phase velocity and electromechanical coupling coefficient (k2) while ensuring the width of the passive region 14. In some embodiments, the resonator structure may have a phononic crystal (PC) structure embedded in the passive or active region 13. An example of a phononic crystal structure at the passive region 14 can be a Bragg reflector, which can effectively increase the acoustic insulation at the passive region 14 and improve the Q value of the resonator.

[0094] In one embodiment, Figure 22-23 As shown, the resonator is further provided with a support column 20, which is fixedly connected to the passive region 14. The height h1 of the support column 20 can be set between 0.5 μm and 4 μm, and the width s1 of the support column 20 is 0.2 to 1 times the width of the passive region. The material of the support column 20 includes SiO 2, porous silicone resin, Al 2 O 3 、AlN、Ta 2 O 5 , one of Al, Cu, Ti, Si and Pt.

[0095] like Figure 22-23 As shown, the support column 20 includes a first end and a second end, the first end is fixedly connected to the passive region 14, and the second end is connected to the support base 30. The support column 20 can form a suspended region between the piezoelectric substrate 10 and the support base 30 to prevent the piezoelectric substrate 10 from directly contacting the support base 30 and causing leakage loss of the bulk acoustic wave. In one embodiment, an isolation layer 301 is further provided between the support base 30 and the support column 20, and the isolation layer 301 includes a diamond-like carbon film (DLC), a silicon dioxide film (SiO 2 ) and aluminum film (Al) composed of one or more of the stacked structure, the isolation layer 301 can further effectively reduce the leakage loss of the piezoelectric substrate 10 body acoustic wave.

[0096] The support method and structure of the piezoelectric substrate 10 are crucial to the performance of the entire resonator device. A good support structure can significantly improve the performance, reliability, yield rate of the resonator, and the thermal performance and life of the final device. The advantage of the support structure using support columns in the passive area of ​​the present application is that the acoustic energy in the passive area is minimal, so the acoustic leakage to the substrate piezoelectric substrate is minimal. By arranging support columns in the passive area of ​​the present application, the Q value and overall performance of the resonator can be significantly improved.

[0097] Fig.24 The lateral excitation bulk acoustic wave resonator of the embodiment of the present invention is shown in FIG. 2 ) Q value curve at height, Fig.25 The lateral excited BAW resonator of the embodiment of the present invention is shown in FIG. 2 ) width. Fig.24 As shown, the Q value of the resonator near the resonance frequency range is about 500, which does not reach the highest Q value of 1100 of an independent structure (without any external support). This is because the sound wave is partially leaked and attenuated in the passive area 14. In the graphical shrinkage coefficient (n3) used to characterize the reduction of the column width, when n3=0.25, it is a full-width column (that is, the width of the support column 20 is equal to the width of the passive area 14), and when n3=0.05 (that is, the width of the support column 20 is 0.2 times the width of the passive area 14), it is a narrower case. Fig.25As shown, the use of narrow pillars can effectively reduce leakage, and the Q value of the resonator using narrow pillars is significantly increased. In addition, the density of the support pillars 20 (the number of support pillars 20 within the entire length of the resonator) can be reduced to obtain a higher Q value. This example uses support pillars 20 to support the piezoelectric substrate 10, which can effectively improve the reliability, thermal conductivity and durability of the resonator, and can release the stress of the piezoelectric substrate 10 caused by thermal effects, etc. by supporting it.

[0098] Fig.26 The graph shows the relationship between the transversely excited bulk acoustic wave resonator and the resonator Q value under different materials and thicknesses of the isolation layer 301 according to the embodiment of the present invention. The relationship curve compares the Q value of different materials such as diamond film (DLC), silicon dioxide film (SiO 2 ) and the insulation effect of aluminum film (Al). Fig.26 It can be seen that the provision of the isolation layer 301 can reduce the leakage loss of the sound wave, thereby effectively improving the Q value of the resonator.

[0099] This embodiment further provides a filter, which includes at least one transversely excited bulk acoustic wave resonator as described in the above embodiment.

[0100] It should be noted that the above example is based on an example in which a resonator with a wavelength width includes two electrode groups (a first electrode group 11 and a second electrode group 12). In other embodiments, a resonator with a wavelength width may also include three or more electrode groups (such as adding a third electrode group, a fourth electrode group, etc.), and the spacing between the electrode groups may be the same or different, which can be determined based on the actual requirements of the resonator performance.

[0101] Example 2

[0102] like Figure 27 to Figure 29 As shown, this embodiment provides a transversely excited bulk acoustic wave resonator, whose basic structure is as in Embodiment 1, wherein the difference from Embodiment 1 is that:

[0103] like Fig. 27 As shown, the cross-sectional shape of the first sub-electrodes 111 , 112 and the second sub-electrodes 121 , 122 may be set to be a triangle or a trapezoid.

[0104] like Fig.28 As shown, the cross-sectional shape of the first sub-electrodes 111 , 112 and the second sub-electrodes 121 , 122 may also be set to be dumbbell-shaped or arc-shaped, and the arc-shaped here may include a circle or an ellipse, etc.

[0105] like Fig.29 As shown, the cross-sectional shapes of the first sub-electrodes 111 , 112 and the second sub-electrodes 121 , 122 may also be set to be stepped.

[0106] Example 3

[0107] like Fig.30 As shown, this embodiment provides a transversely excited bulk acoustic wave resonator, whose basic structure is as in Embodiment 1, wherein the difference from Embodiment 1 is that the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 are inclined at an angle and penetrate the piezoelectric substrate 10. At the same time, the widths of the two first sub-electrodes 111, 112 or the two second sub-electrodes 121, 122 can be set to be the same or different.

[0108] Example 4

[0109] like Fig.31 As shown, this embodiment provides a laterally excited bulk acoustic wave resonator, whose basic structure is as in Embodiment 1, wherein the difference from Embodiment 1 is that the first sub-electrodes 111, 112 and the second sub-electrodes 121, 122 can be set to be a phononic crystal material with a periodic structure or a semi-periodic structure, or a metamaterial with a periodic structure or a semi-periodic structure.

[0110] Example 5

[0111] like Fig.32 As shown, this embodiment provides a laterally excited bulk acoustic wave resonator, whose basic structure is as in Embodiment 1, wherein the difference from Embodiment 1 is that the piezoelectric substrate 10 in the passive region 14 of the resonator is partially removed to form a cavity 601, and the cavity 601 can effectively reduce the acoustic wave leakage loss in the passive region 14 and improve the Q value of the resonator.

[0112] Example 6

[0113] like Fig.33 and Fig.34 As shown, this embodiment provides a laterally excited bulk acoustic wave resonator, whose basic structure is as in Embodiment 1, wherein the difference from Embodiment 1 is that the piezoelectric substrate 10 in the passive region 14 is partially or completely removed to form a filling cavity, and the filling cavity is filled with a functional structure, and the functional structure is used to improve one or more of the electrical properties, mechanical properties or thermal properties of the resonator. Fig.33 The piezoelectric substrate 10 in the inactive region 14 is shown to be completely removed to form a filling cavity, which is filled with a functional structure 602. Fig.34 The piezoelectric substrate 10 in the inactive region 14 is shown partially removed to form a filling cavity, which is filled with a functional structure 603. In some embodiments, as shown in FIG. Fig.34 As shown, the electrode group may include more sub-electrodes, and the number of sub-electrodes may be, for example, 3 or more, and is not limited to the examples listed above.

[0114] In one embodiment, the material of the functional structure includes one of a phononic crystal and a metamaterial.

[0115] In one specific example, the functional structure includes a Bragg reflector structure.

[0116] Example 7

[0117] like Fig.35 and Fig.36 As shown, this embodiment provides a transversely excited bulk acoustic wave resonator, whose basic structure is as in Embodiment 1, wherein the difference from Embodiment 1 is that:

[0118] like Fig.35 As shown, a functional structure 604, such as a phononic crystal, a metamaterial, etc., may be provided inside the active region 13 to improve the performance of the resonator.

[0119] like Fig.36 As shown, the upper surface and / or the lower surface of the active region 13 may be provided with a functional structure 605, such as a phononic crystal, a metamaterial, etc., to improve the performance of the resonator.

[0120] As described above, the transversely excited bulk acoustic wave resonator and filter of the present invention have the following beneficial effects:

[0121] The present invention sets a first electrode group 11 and a second electrode group 12 in a piezoelectric substrate. The first electrode group 11 and the second electrode group 12 are configured to penetrate the piezoelectric substrate along the thickness direction of the piezoelectric substrate. The first electrode group 11 includes at least two first sub-electrodes 111 and 112 arranged at intervals, and the second electrode group 12 includes at least two second sub-electrodes 121 and 122 arranged at intervals. Different electrode groups are configured to apply different electric potentials to form active regions 13 between different electrode groups, and different sub-electrodes in the same electrode group are configured to apply the same electric potential to form inactive regions 14 between different sub-electrodes in the same electrode group. On the one hand, the present invention distributes a uniform electric field in the active region 13, which can realize transverse excitation of bulk acoustic waves with high phase velocity and extremely high piezoelectric coupling; on the other hand, various functional structures can be set in the passive region 14 to improve the electrical performance, mechanical performance or thermal performance of the resonator. The piezoelectric strain of the passive region 14 is low when an electric field is applied, so a support column 20 can also be set in the passive region 14. The support column 20 is set in the passive region 14, which has lower bulk acoustic wave loss, and at the same time as the resonator is supported, it is ensured that the resonator has a higher Q value.

[0122] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0123] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A transversely excited bulk acoustic wave resonator, characterized in that: The resonator comprises: Piezoelectric substrate; A first electrode group and a second electrode group are arranged at intervals in the piezoelectric substrate, the first electrode group and the second electrode group are configured to penetrate the piezoelectric substrate along the thickness direction of the piezoelectric substrate, the first electrode group includes at least two first sub-electrodes arranged at intervals, the second electrode group includes at least two second sub-electrodes arranged at intervals, different electrode groups are configured to apply different potentials to form active regions between different electrode groups, and different sub-electrodes in the same electrode group are configured to apply the same potential to form inactive regions between different sub-electrodes in the same electrode group.

2. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The thickness d of the piezoelectric substrate is in the range of 0.09λ≤d≤0.13λ, wherein λ is the wavelength of the bulk acoustic wave.

3. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The width of the passive region is 0.005λ to 0.05λ, wherein λ is the wavelength of the bulk acoustic wave.

4. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The duty ratio range of the first electrode group and the second electrode group is set to be between 0.25 and 0.

3.

5. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The width of the first sub-electrode and the second sub-electrode is 10 nanometers to 100 nanometers, or the width of the first sub-electrode and the second sub-electrode is 0.01 times to 0.05 times the wavelength of the bulk acoustic wave.

6. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: Also included is a support column, which is fixedly connected to the passive area.

7. The transversely excited bulk acoustic wave resonator according to claim 6, characterized in that: The width of the support column is 0.2 to 1 times the width of the passive region.

8. The transversely excited bulk acoustic wave resonator according to claim 6, characterized in that: The support column includes a first end and a second end, the first end is fixedly connected to the passive area, and the second end is connected to the supporting base. An isolation layer is also arranged between the supporting base and the support column, and the isolation layer includes a stacked structure composed of one or more of a diamond-like film, a silicon dioxide film and an aluminum film.

9. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The first sub-electrode and the second sub-electrode vertically penetrate the piezoelectric substrate or penetrate the piezoelectric substrate at an angle.

10. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The first sub-electrode and the second sub-electrode are made of a phononic crystal material with a periodic structure or a semi-periodic structure, or are made of a metamaterial with a periodic structure or a semi-periodic structure.

11. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The piezoelectric substrate in the inactive region is partially removed to form a cavity.

12. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: The piezoelectric substrate in the passive area is partially or completely removed to form a filling cavity, and the filling cavity is filled with a functional structure, and the functional structure is used to improve one or more of the electrical performance, mechanical performance or thermal performance of the resonator.

13. The transversely excited bulk acoustic wave resonator according to claim 1, characterized in that: A functional structure is also formed inside the active region or / and on the surface of the active region, and the functional structure is used to improve one or more of the electrical properties, mechanical properties or thermal properties of the resonator.

14. A filter, characterized in that: The filter comprises at least one transversely excited bulk acoustic wave resonator according to any one of claims 1 to 13.

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