Resonator with transverse mode suppression structure and manufacturing method thereof

Abstract

The invention provides a resonator with a transverse mode suppression structure and a manufacturing method thereof.The resonator comprises a piezoelectric substrate, an electrode layer, a passivation layer and a suppression layer, the electrode layer, the passivation layer and the suppression layer are located on the piezoelectric substrate, the electrode layer comprises two interdigital electrodes oppositely arranged in the first direction, and each interdigital electrode comprises a bus bar and a plurality of electrode fingers; gaps are formed between the electrode fingers in different interdigital electrodes and the bus bars, and the passivation layer is embedded between the two interdigital electrodes in the first direction and covers the electrode fingers and the gaps; the suppression layer comprises two suppression units which are oppositely arranged in the first direction, and each suppression unit is connected with one bus bar to cover the gap and partially overlaps with at least one electrode finger located on the different side. According to the resonator, the suppression of a transverse mode is realized through the additionally arranged suppression layer structure, meanwhile, the quality factor is improved, the resonator can be suitable for various resonator structures and a wide frequency range, the durability and the linearity of the resonator are improved, the working stability of the resonator is further improved, and the service life of the resonator is further prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of resonators, and relates to a resonator with a transverse mode suppression structure and a manufacturing method thereof. Background Art

[0002] A surface acoustic wave resonator generally includes a substrate made of a piezoelectric material and at least two interdigital transducers located on the piezoelectric substrate and composed of multiple pairs of crossed conductive electrode fingers. Please refer to Figure 1 and Figure 2 , Figure 1 which shows a partial top view structural schematic diagram of a resonator, Figure 2 and Figure 1 which shows a longitudinal sectional structure at I-I' in

[0003] and a corresponding schematic diagram of the change in the acoustic wave propagation speed. The interdigital transducer includes a bus bar 101 and electrode fingers 102. The interdigital transducer converts electrical-acoustic signals through the piezoelectric effect, and the main mode therein is the surface acoustic wave. A device system composed of two transducers and a piezoelectric substrate in a surface acoustic wave resonator has specific frequency response characteristics, and this characteristic can be controlled by manipulating the materials and structures of the transducers and the substrate. Moreover, the device has advantages such as high stability, small volume, and high quality factor Q, and is widely used in various acoustic devices. For example, a radio frequency filter based on a surface acoustic wave resonator is usually used in wireless communication devices, and excellent performance is presented by utilizing the surface acoustic wave resonator to meet the requirements of increasing frequency bands and restrictions on the radio frequency spectrum.

[0004] Therefore, how to provide a resonator with a transverse mode suppression structure and a manufacturing method thereof, so as to achieve a good suppression effect on the transverse mode generated during the operation of the resonator and improve the quality factor, while not additionally increasing the process difficulty, has become an important technical problem urgently to be solved by those skilled in the art.

[0005] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solution of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of the present application. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a resonator with a transverse mode suppression structure and a manufacturing method thereof, which are used to solve the problems that the method for suppressing the transverse mode in the prior art has a limited suppression effect on the transverse mode or requires a high-resolution process to increase the manufacturing process difficulty.

[0007] To achieve the above object and other related objects, the present invention provides a resonator with a transverse mode suppression structure, including:

[0008] A piezoelectric substrate;

[0009] An electrode layer, located above the piezoelectric substrate. The electrode layer includes two interdigital electrodes oppositely arranged in a first direction. Each interdigital electrode includes a bus bar and a plurality of electrode fingers. The plurality of electrode fingers in the same interdigital electrode are spaced apart in a second direction and are all connected to the bus bar; there is a gap between the electrode fingers and the bus bar in different interdigital electrodes, and the second direction is perpendicular to the first direction.

[0010] A passivation layer, located above the piezoelectric substrate. The passivation layer is embedded between the two interdigital electrodes in the first direction and covers the electrode fingers and the gap.

[0011] A suppression layer, located above the piezoelectric substrate. The suppression layer includes two suppression units oppositely arranged in the first direction. Each suppression unit is respectively connected to a bus bar and extends along the first direction to cover the gap and partially overlap at least one electrode finger on different sides of the suppression unit.

[0012] Optionally, when the distance between two adjacent electrode fingers in the same interdigital electrode is λ, the width range of the partial overlap between the suppression unit and the electrode finger is 0 to 1.0λ, and / or, the thickness range of the part of the suppression unit located above the gap and above the electrode finger is 1 to 100 nm.

[0013] Optionally, the suppression unit is connected to the side of the bus bar away from the piezoelectric substrate and extends above the passivation layer.

[0014] Optionally, the thickness of the part of the suppression unit located above the bus bar is greater than or equal to the thickness of the part of the suppression unit located above the passivation layer.

[0015] Optionally, the suppression unit is also vertically embedded in the passivation layer, and the part of the suppression unit vertically embedded in the passivation layer is located above the gap.

[0016] Optionally, the suppression unit is connected to the side of the bus bar and is embedded in the passivation layer in a first direction.

[0017] Optionally, the part of the suppression unit located above the gap has at least one blind groove and / or at least one through groove. The blind groove opens from the side of the suppression unit facing the piezoelectric substrate and / or the side facing away from the piezoelectric substrate and extends vertically. The through groove opens from the side of the suppression unit facing away from the piezoelectric substrate and exposes at least a part of at least one of the electrode fingers.

[0018] Optionally, the passivation layer has a groove, the vertical projection of the groove is located between the vertical projections of the two suppression units, and the part of the passivation layer surrounding the groove forms a raised frame.

[0019] Optionally, the part of the suppression unit located above the gap and above the electrode fingers includes a plurality of suppression blocks arranged at intervals in a second direction, and at least one of the suppression blocks overlaps with a part of the electrode finger on a different side from the suppression block.

[0020] Optionally, the suppression unit includes a plurality of first suppression blocks, and the first suppression blocks extend above the gap in a first direction and overlap with parts of the electrode fingers on different sides from the first suppression blocks.

[0021] Optionally, the suppression unit further includes a plurality of second suppression blocks, and the second suppression blocks extend above the electrode fingers on the same side as the second suppression blocks in a first direction. The plurality of first suppression blocks and the plurality of second suppression blocks in the same suppression unit are arranged alternately, and the first suppression blocks and the second suppression blocks in different suppression units are arranged opposite to each other. The first suppression blocks and the second suppression blocks have the same or different morphologies.

[0022] Optionally, the interdigital electrode further includes a plurality of dummy fingers connected to the bus bar. The plurality of dummy fingers in the same interdigital electrode are arranged alternately and at intervals with the plurality of electrode fingers and embed the dummy fingers into the gap. There is a preset distance between the dummy fingers and the electrode fingers in different interdigital electrodes.

[0023] Optionally, the material of the suppression layer includes at least one of a metal material and a high-density dielectric material. The metal material includes at least one of Al, Ti, Cu, Pt, and Au. The high-density dielectric material includes at least one of Ta2O5, HfO2, and BaTiO3.

[0024] The present invention also provides a method for manufacturing a resonator having a lateral mode suppression structure, including the following steps:

[0025] Provide a piezoelectric substrate;

[0026] Form an electrode layer above the piezoelectric substrate. The electrode layer includes two interdigital electrodes oppositely arranged in a first direction. Each interdigital electrode includes a bus bar and a plurality of electrode fingers. The plurality of electrode fingers in the same interdigital electrode are spaced apart in a second direction and are all connected to the bus bar. There is a gap between the electrode fingers and the bus bar in different interdigital electrodes. The second direction is perpendicular to the first direction;

[0027] Form a passivation layer above the piezoelectric substrate. The passivation layer is embedded between the two interdigital electrodes in the first direction and covers the electrode fingers and the gap;

[0028] Form a suppression layer above the piezoelectric substrate. The suppression layer includes two suppression units oppositely arranged in the first direction. Each suppression unit is respectively connected to a bus bar and extends along the first direction to cover the gap and partially overlap at least one electrode finger connected to the other bus bar.

[0029] As described above, the resonator with a lateral mode suppression structure of the present invention can improve the quality factor of the resonator while suppressing the lateral mode through the energy restriction effect of the additionally provided suppression layer structure. It is applicable to a variety of resonator structures and a wide frequency range, and the manufacturing process does not require special high-resolution processes. The structure is simple and the manufacturing process is mature. And after further improving and optimizing the suppression layer structure, the piston mode effect can be achieved without using a hammerhead structure or a selective disassembly method, reducing the scattering loss. In addition, the material selection of the suppression layer makes the suppression layer act as a heat sink due to its good thermal conductivity in addition to the lateral mode suppression effect, which can improve the durability and linearity of the resonator, and improve the working stability and service life of the resonator. The method for manufacturing a resonator with a lateral mode suppression structure of the present invention can effectively improve the structural performance of the resonator without special high-resolution processes. The process steps are simple and the cost is low, and the large-scale production of high-performance resonators can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Shown is a partial top view structural schematic diagram of a resonator.

[0031] Figure 2 Shown as along Figure 1 The longitudinal sectional structure at I-I' in and the schematic diagram of the corresponding change in acoustic wave propagation velocity.

[0032] Figure 3 Shown as the partial top view structure schematic diagram of the resonator with a transverse mode suppression structure of the present invention in Embodiment 1.

[0033] Figure 4 Shown as along Figure 3 The longitudinal sectional structure at II-II' in and the schematic diagram of the corresponding change in acoustic wave propagation velocity.

[0034] Figure 5 Shown as Figure 4 The first enlarged schematic diagram of the local structure at the dashed box in.

[0035] Figure 6 Shown as the effect curve diagram of the conductance characteristic varying with frequency when the suppression unit and the electrode finger part of the resonator with a transverse mode suppression structure of the present invention overlap with different widths.

[0036] Figure 7 Shown as the effect curve diagram of the quality factor Q varying with frequency when the suppression unit and the electrode finger part of the resonator with a transverse mode suppression structure of the present invention overlap with different widths.

[0037] Figure 8 Shown as the effect curve diagram of the conductance characteristic varying with frequency when the thicknesses of the parts of the suppression unit of the resonator with a transverse mode suppression structure of the present invention located above the gap and above the electrode finger are different.

[0038] Figure 9 Shown as the effect curve diagram of the quality factor varying with frequency when the thicknesses of the parts of the suppression unit of the resonator with a transverse mode suppression structure of the present invention located above the gap and above the electrode finger are different.

[0039] Figure 10 Shown as the schematic diagram of the negative linear relationship between the passivation layer thickness and the suppression layer thickness in the resonator with a transverse mode suppression structure of the present invention.

[0040] Figure 11 Shown as the effect curve diagram of the quality factor Q varying with frequency under different passivation layer thicknesses in the resonator with a transverse mode suppression structure of the present invention.

[0041] Figure 12 Shown as Figure 4 The second enlarged schematic diagram of the local structure at the dashed box in.

[0042] Figure 13 Shown asFigure 4 The third enlarged schematic diagram of the local structure at the dashed box in the middle.

[0043] Figure 14 Shown as Figure 4 The fourth enlarged schematic diagram of the local structure at the dashed box in the middle.

[0044] Figure 15 Shown is the schematic diagram of the local longitudinal sectional structure when the resonator with the lateral mode suppression structure of the present invention has false fingers.

[0045] Figure 16 Shown Figure 15 The schematic diagram of the top view structure of the electrode layer in the shown resonator.

[0046] Figure 17 Shown is the first schematic diagram of the local longitudinal sectional structure in Embodiment 2 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention is embedded in the passivation layer.

[0047] Figure 18 Shown is the second schematic diagram of the local longitudinal sectional structure in Embodiment 2 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention is embedded in the passivation layer.

[0048] Figure 19 Shown is the third schematic diagram of the local longitudinal sectional structure in Embodiment 2 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention is embedded in the passivation layer.

[0049] Figure 20 Shown is the fourth schematic diagram of the local longitudinal sectional structure in Embodiment 2 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention is embedded in the passivation layer.

[0050] Figure 21 Shown is the schematic diagram of the top view structure in Embodiment 3 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention has multiple through slots.

[0051] Figure 22 Shown is the schematic diagram of the top view structure in Embodiment 3 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention has one through slot.

[0052] Figure 23 Shown is the first schematic diagram of the top view structure in Embodiment 4 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention includes multiple suppression blocks.

[0053] Figure 24 Shown is the second schematic diagram of the top view structure in Embodiment 4 when the suppression unit in the resonator with the lateral mode suppression structure of the present invention includes multiple suppression blocks.

[0054] Figure 25 The third top - view structural schematic diagram in Embodiment 4 when the suppression unit in the resonator with a lateral - mode suppression structure of the present invention includes multiple suppression blocks.

[0055] Figure 26 The fourth top - view structural schematic diagram in Embodiment 4 when the suppression unit in the resonator with a lateral - mode suppression structure of the present invention includes multiple suppression blocks.

[0056] Figure 27 The fifth top - view structural schematic diagram in Embodiment 4 when the suppression unit in the resonator with a lateral - mode suppression structure of the present invention includes multiple suppression blocks.

[0057] Description of component numbers

[0058] 10 Piezoelectric substrate

[0059] 20 Electrode layer

[0060] 101, 21 Bus bar

[0061] 211 Lower bus bar

[0062] 212 Upper bus bar

[0063] 102, 22 Electrode finger

[0064] 23 Gap

[0065] 24 False finger

[0066] 30 Passivation layer

[0067] 31 Groove

[0068] 32 Protruding frame

[0069] 40 Suppression layer

[0070] 41 Suppression unit

[0071] 411 Blind slot

[0072] 412 Through - slot

[0073] 413 Suppression block

[0074] 413a First suppression block

[0075] 413b Second suppression block Detailed implementation manners

[0076] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0077] Please refer to Figures 3 to 27 . It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0078] Embodiment 1

[0079] This embodiment provides a resonator with a lateral mode suppression structure. Please refer to Figure 3 and Figure 4 , where Figure 3 shows a top view structural schematic diagram of the resonator, Figure 4 shows a longitudinal sectional structural schematic diagram along the II-II' in Figure 3 . The resonator includes a piezoelectric substrate 10, an electrode layer 20, a passivation layer 30, and a suppression layer 40.

[0080] Specifically, the electrode layer 20 is located above the piezoelectric substrate 10. The electrode layer 20 includes two interdigital electrodes oppositely arranged in a first direction ( Figure 3 shown as the X direction in Figure 3 shown as the Y direction in

[0081] Specifically, the resonator structure of this embodiment adds a suppression layer on the basis of a conventional resonator structure, such that the suppression layer is connected to the bus bar and extends above the gap and above the edge region of the electrode fingers (including two cases where the suppression unit just extends to the edge of the electrode fingers and further extends above the electrode fingers), that is, the suppression layer can be regarded as an extended structure of the bus bar. As shown in Figure 4 the sound velocity change diagram, the propagation velocity of the sound wave in the region where the suppression unit overlaps with the electrode fingers is significantly lower than the propagation velocity of the sound wave in the main region of the electrode fingers (the region not covered by the suppression layer); and, compared with the distribution trend of the propagation velocity of the surface acoustic wave in the conventional resonator structure, when the propagation velocity of the sound wave in the electrode finger region is the same (i.e., Figure 2 V in 1a is the same as Figure 4 V in 1b ), the propagation velocity of the sound wave in the region where the gap is located is relatively reduced (i.e., Figure 4 V in 2b is less than Figure 2 V in 2a ). After analysis, it is considered that the reason for the above-mentioned sound wave propagation velocity is that: due to the acoustic interaction and phase shift effect with the surface acoustic wave, the suppression layer causes the non-uniform acoustic impedance interaction of the transverse stray mode whose propagation direction is perpendicular to the propagation direction of the surface acoustic wave in the edge region of the electrode fingers (i.e., the partial overlap region) and the gap region, and introduces a large amount of acoustic stray energy into the passivation layer through the phase shift effect, thereby suppressing the interference of the transverse mode on the performance of the resonator. In addition, by improving and optimizing the suppression structure, the piston mode effect can be introduced on the basis of the basic structure to further improve the working performance of the resonator (please refer to the following for details).

[0082] As an example, the material of the piezoelectric substrate 10 includes but is not limited to 128Y-cut lithium niobate (LN) material.

[0083] As an example, please refer to Figure 5 , shown as Figure 4Schematic diagram of the first local structure magnification at the dashed box in the middle. The height of the bus bar 21 is greater than the height of the electrode finger 22. The passivation layer 30 is embedded in the area between the two bus bars 21. In other embodiments, the passivation layer 30 may also be partially embedded in the area where the bus bar 21 is located but does not completely cover the bus bar 21. In actual applications, the structure of the passivation layer is deformed based on actual needs. "The height of the bus bar 21 is greater than the height of the electrode finger 22" can be regarded as the bus bar 21 including a lower bus bar 211 that is vertically flush with the electrode finger 22 and an upper bus bar 212 located above the lower bus bar 211. Further, the material of the upper bus bar 212 may be the same as or different from the material of the lower bus bar 211. In this embodiment, the material of the upper bus bar is different from the material of the lower bus bar and the thickness of the upper bus bar is greater than the thickness of the lower bus bar, that is, the bus bar is a stacked structure, which can realize the characteristics of a low-speed and lossy (high damping) region. In this case, first, the structure of the suppression layer is optimized to achieve the best piston mode effect, and then complete spurious suppression can be achieved by adjusting the gap region. It should be noted that although the upper and lower bus bars are not distinguished in the subsequent drawings, it does not mean that the materials of the upper and lower bus bars are the same material.

[0084] As an example, the material of the passivation layer 30 includes at least one of SiO2, SiN, or other dielectric materials with positive thermal velocity characteristics. In this embodiment, the material of the passivation layer is SiO2. The suppression layer can, on the one hand, play an electrical insulation role between the suppression layer and the electrode finger, and on the other hand, act as an acoustic guiding layer to enable surface acoustic waves to propagate in the passivation layer and reduce the lateral energy diffusion during the operation of the resonator. In addition, the surface of the passivation layer facing away from the piezoelectric substrate needs to be kept flat (which can be achieved through planarization treatment after manufacturing), which can reduce unnecessary scattering losses generated when the suppression layer is formed thereon, thereby improving the working performance of the resonator. In this embodiment, the material of the passivation layer is SiO2, and the thickness of the passivation layer is 1 μm.

[0085] As an example, the material of the electrode layer 20 includes one or several of metal materials such as Al, Ti, Cu, Pt, and Au. In this embodiment, the material of the electrode layer is Cu.

[0086] As an example, the material of the suppression layer 40 includes at least one of a metal material and a high-density dielectric material. The metal material includes at least one of Al, Ti, Cu, Pt, and Au. The high-density dielectric material includes at least one of Ta2O5, HfO2, and BaTiO3 (the densities of the above three high-density dielectric materials are relatively high, with a relative density greater than 6.0 g / cm 3)。Selecting the above materials to form the suppression layer can bring a certain mass loading effect (phase shift effect) to achieve the piston mode and reduce the speed of the transverse mode, thereby improving the performance of the resonator. The material of the suppression layer 40 is preferably a metal material to simultaneously achieve the radiator function. Further, the material of the suppression layer 40 can be the same as or different from the material of the electrode layer 20. In this embodiment, the material of the suppression layer is the same as the material of the upper bus bar.

[0087] Specifically, in this embodiment, on the one hand, the suppression layer made of a metal material is connected to the bus bar to improve the electric field distribution in the gap region (achieved by the electrostatic effect generated by the electrical interaction in the region where the suppression layer overlaps with the edge of the electrode finger), and the electrical effect presented by the potential linearization of the electric field in this region is used to reduce the high-order nonlinearity and distortion of signal transmission. Based on the acoustic interaction and phase shift effect between the suppression layer and the surface acoustic wave, the suppression of the transverse spurious mode is achieved to improve the working performance of the resonator. On the other hand, the material properties of the suppression layer enable it to have good heat conduction performance and thus act as a radiator, further improving the durability and linearity of the resonator, thereby improving the working stability and service life of the resonator without the need to additionally set up a heater structure and avoiding the increase in the overall volume of the resonator. Of course, in other embodiments, one or several of the above-mentioned high-density dielectric materials can also be used as the constituent materials of the suppression layer, and the effect of suppressing the transverse spurious mode to improve the working performance of the resonator can also be achieved. The material of the suppression layer 40 is preferably a metal material to simultaneously achieve the radiator function, and reasonable selection should be made based on actual requirements during application.

[0088] As an example, when the distance between two adjacent electrode fingers 22 in the same interdigital electrode is λ (such as Figure 3 the λ shown in Figure 5 ), the width range (

[0089] Please refer to Figure 6, it shows a graph of the conductance characteristics of the resonator varying with frequency when the suppression unit overlaps with the electrode finger portion by different widths. When the width of the partial overlap is less than 0 (e.g., -0.1λ), it means that the suppression unit does not extend above the electrode finger 22 (i.e., the suppression unit and the electrode finger do not partially overlap in the first direction); when the width of the partial overlap is greater than 0 (e.g., 0.1λ), it means that the suppression unit extends above the electrode finger (i.e., the suppression unit and the electrode finger partially overlap in the first direction). When other parameters are kept the same, after comparing the conductance characteristics of resonators with different widths of the partial overlap between the suppression unit and the electrode finger, it is found that the transverse mode of the resonator is suppressed to varying degrees at different above widths. It can be seen that when the suppression unit partially overlaps with the electrode finger, the suppression effect on the transverse mode is relatively obvious (compared with the case where the suppression unit only extends above a part of the gap 23), especially when the overlap range between the suppression unit and the electrode finger is 0.2λ, the effect is the best, and the transverse mode is almost completely suppressed in the frequency range of 860 MHz to 880 MHz, thus effectively improving the working performance of the resonator. It should be noted that although Figure 5 does not compare the relevant data curves when the overlap width is above 0.8λ, in fact, when the overlap width is above 0.8λ, there is also a certain suppression effect on the transverse mode.

[0090] In addition, please refer to Figure 7 , it shows a graph of the quality factor Q of the resonator varying with frequency when the suppression unit overlaps with the electrode finger portion by different widths (in Figure 7, Fr and Fa respectively correspond to the resonance frequency and anti-resonance frequency of the resonator). From Figure 7 , it can be seen that the quality factor Q of the resonator does not change significantly due to the change in the overlap width between the suppression unit and the electrode finger (i.e., the partial overlap between the suppression unit and the electrode finger does not affect the quality factor Q of the resonator). It should be noted that when the above overlap width range is small, the suppression unit is mainly distributed above the gap, and the electrostatic interaction with the periodically arranged electrode fingers is small. At this time, the influence of the electrostatic interaction between the two on the resonator performance can be ignored. However, as the overlap range gradually increases, the electrostatic interaction between the suppression unit and the periodically arranged electrode fingers also gradually increases, and the influence on the working process of the resonator gradually becomes prominent. Therefore, the overlap width between the suppression unit and the electrode finger needs to be strictly limited within the above interval range, and preferably 0.1λ to 0.5λ (including the end values). At the same time, the setting of the suppression unit plays a role of transition and buffering for the acoustic wave propagation speed, ensuring the working stability of the resonator.

[0091] As an example, the thickness range of the part of the suppression unit 41 located above the gap 23 and above the electrode finger 22 ( Figure 5h) is 1 to 100 nm (when the thickness of the suppression unit 41 is equal everywhere, the thickness range of the part of the suppression unit 41 located above the bus bar 21 is also 1 to 100 nm), including but not limited to 1 nm, 25 nm, 40 nm, 75 nm, and 100 nm.

[0092] Please refer to Figure 8 , which shows a graph of the conductance characteristics of the resonator changing with frequency when the thicknesses of the parts of the suppression unit located above the gap and above the electrode fingers are different. When other parameters are kept consistent (such as keeping the overlapping width of the suppression unit and the electrode finger part at 0.2λ unchanged), after comparing the conductance characteristics of resonators with different above-mentioned thicknesses, it is found that the transverse mode of the resonator is suppressed to varying degrees at different above-mentioned thicknesses. Among them, the transverse mode suppression effect is relatively good in the range of 20 nm to 60 nm for the above-mentioned thickness, and when the above-mentioned thickness is 40 nm, the transverse mode generated during the operation of the resonator is completely suppressed (as Figure 8 indicated by the arrow in

[0093] In addition, please refer to Figure 9 , which shows a graph of the quality factor Q of the resonator changing with frequency when the thicknesses of the parts of the suppression unit located above the gap and above the electrode fingers are different. After synchronously analyzing the quality factor Q of the resonator, it can be known that as the above-mentioned thickness increases, the acoustic shock phenomenon generated in the corresponding suppression layer intensifies, resulting in a decreasing trend of the quality factor Q of the resonator. Among them, when the above-mentioned thickness is 1 nm, since the very thin suppression layer does not generate acoustic shock, the quality factor Q remains in a relatively high state, while when the above-mentioned thickness is relatively thick (for example, ≥100 nm), the generated acoustic shock is quite high, making the decreasing trend of the quality factor Q obvious, and it can be seen from Figure 9 that when the above-mentioned thickness is 40 nm, the decrease amplitude of the quality factor Q of the resonator can be ignored, and even in the low-frequency region (for example, ≤840 MHz), the quality factor Q performs better.

[0094] Furthermore, after analyzing the performance of resonators with suppression layers and passivation layers of different above-mentioned thicknesses, the following rule is summarized: To achieve a better transverse mode suppression effect, it is necessary to ensure that the thickness of the passivation layer shows a negative linear correlation with the above-mentioned thickness of the suppression layer (as Figure 10 shown). Therefore, in practical applications, if the thickness of the passivation layer is relatively thin, the thickness of the corresponding suppression layer needs to be increased, and when the thickness of the passivation layer is relatively thick, the thickness of the suppression layer needs to be decreased. For example, when the passivation layer is relatively thick (for example, about 1450 nm), the thickness of the suppression layer needs to be relatively low (for example, about 20 nm) to have a better suppression effect. Please refer to Figure 11, showing the effect curve of the quality factor Q of the resonator varying with frequency at different passivation layer thicknesses (it should be noted that Figure 10 and Figure 11 are all data collected when the overlapping width between the suppression unit and the electrode fingers is 0.2λ). The quality factor Q of the resonator does not decrease significantly due to different thicknesses of the passivation layer 30. When the thickness of the passivation layer 30 is relatively high (≥1250 nm), Figure 11 the reason for the phenomenon of increased spurious in the corresponding curve in [] is that the widths of the suppression unit above the gap and above the electrode fingers are not reasonably adjusted. Therefore, when designing the resonator structure, it is necessary to optimize the thickness of the suppression layer (especially the thickness of the part of the suppression unit above the gap and above the electrode), the overlapping range between the suppression unit and the electrode fingers, and the corresponding passivation layer thickness to ensure better performance of the resonator.

[0095] As an example, please refer to Figure 5 and Figures 12 to 14 , the suppression unit 41 is connected to the side of the bus bar 21 away from the piezoelectric substrate 10 and extends above the passivation layer 30, that is, in this embodiment, the suppression unit includes not only the part above the gap and above the electrode fingers but also the part above the bus bar.

[0096] Furthermore, as shown in Figure 5 and Figure 13 , the thickness of the part of the suppression unit 41 above the bus bar 21 is equal to the thickness of the part of the suppression unit 41 above the passivation layer 30, or, as shown in Figure 12 , the thickness of the part of the suppression unit 41 above the bus bar 21 ( Figure 12 h2 shown in []) is greater than the thickness of the part of the suppression unit 41 above the passivation layer 30 (that is, the part of the suppression unit 41 above the gap 23 and above the electrode fingers) ( Figure 12 h1 shown in []).

[0097] As an example, as shown in Figure 14 , the suppression unit 41 is also vertically embedded in the passivation layer 30, and the part of the suppression unit 41 vertically embedded in the passivation layer 30 is above the gap 23. By etching an opening in the fabricated passivation layer and then filling the opening with the suppression layer material, the above structure can be easily formed, that is, filling an additional structure above the gap, and using this structure to perform an energy confinement function to improve the quality factor Q, durability, and linearity of the resonator. In addition, the part of the suppression unit vertically extending into the passivation layer is near the electrode fingers and can also act as a dummy finger to reduce scattered energy loss and further improve the performance of the resonator.

[0098] As an example, such as Figure 13 As shown, the passivation layer 30 has a groove 31, and the vertical projection of the groove 31 is located between the vertical projections of the two suppression units 41. The portion of the passivation layer 30 surrounding the groove 31 forms a raised frame 32. During actual fabrication, the above structure can be achieved by patterning the passivation layer 30 (even the suppression layer 40). The raised frame 32 can impose a certain degree of restriction on the acoustic wave propagation speed in the corresponding area of the gap 23 and the edge area of the electrode finger 22 to suppress the transverse mode. Correspondingly, the setting of the groove 31 can relatively increase the acoustic wave propagation speed of the portion of the electrode finger 22 located below the groove 31 to specifically improve the performance of the resonator.

[0099] As an example, please refer to Figure 15 and Figure 16 , where Figure 15 shows a schematic diagram of a partial longitudinal sectional structure when the resonator has dummy fingers. Figure 16 shows Figure 15 a schematic top view structure of the electrode layer in the resonator shown. The interdigital electrode further includes a plurality of dummy fingers 24 connected to the bus bar 21. The plurality of dummy fingers 24 in the same interdigital electrode are alternately and spaced apart from the plurality of electrode fingers 22 and the dummy fingers 24 are embedded in the gap 23. There is a preset distance between the dummy fingers 24 in different interdigital electrodes and the electrode fingers 22 (that is, the dummy fingers 24 are located in the gap 23 and the end of the dummy finger 24 away from the bus bar 21 maintains a certain distance from the electrode finger 22 in another interdigital electrode). The setting of the dummy fingers 24 can obtain a better energy confinement effect. In addition, parameters such as the width, thickness, and material of the dummy fingers 24 are preferably the same as the corresponding parameters of the electrode fingers 22, so that the dummy fingers 24 and the electrode fingers 22 can be fabricated simultaneously in one process step during the fabrication process.

[0100] As an example, the resonator includes at least one of a temperature-compensated surface acoustic wave resonator (TC-SAW), an insulating substrate surface acoustic wave resonator (POI-SAW), a solidly mounted resonator (SMR), a laterally excited bulk acoustic wave resonator (XBAR), a longitudinally excited bulk acoustic wave resonator (YBAR), and a thin film bulk acoustic wave resonator (FBAR).

[0101] The resonator with a transverse mode suppression structure in this embodiment can improve the quality factor of the resonator while suppressing the transverse mode through the energy limiting effect of the additionally provided suppression layer structure. It is applicable to various resonator structures and a wide frequency range, and the manufacturing process does not require special high-resolution processes. The structure is simple and the manufacturing process is mature. And after further improving and optimizing the suppression layer structure, the piston mode effect can be achieved without using a hammerhead structure or a selective disassembly method, reducing the scattering loss. In addition, the material selection of the suppression layer enables the suppression layer to act as a heat sink due to its good thermal conductivity in addition to the transverse mode suppression effect, which can improve the durability and linearity of the resonator, and enhance the working stability and service life of the resonator. In addition, adding multiple dummy finger structures in the interdigital electrode structure does not additionally increase the overall volume of the resonator, can better limit the energy during the operation of the resonator while improving the volume utilization rate, thereby further enhancing the working performance of the resonator.

[0102] Embodiment 2

[0103] This embodiment provides a resonator with a transverse mode suppression structure. The difference between this embodiment and Embodiment 1 is that in the resonator of Embodiment 1, the suppression unit is connected to the side of the bus bar away from the piezoelectric substrate and extends above the passivation layer, while in the resonator of this embodiment, the suppression unit is connected to the side of the bus bar and is embedded in the passivation layer in the first direction. Please refer to Figures 17 to 20 , the resonator includes a piezoelectric substrate 10, an electrode layer 20, a passivation layer 30 (please refer to Figure 4 ) and a suppression layer 40 (please refer to Figure 4 ).

[0104] As an example, the suppression unit 41 is connected to the side of the bus bar 21 and is embedded in the passivation layer 30 in the first direction, that is, the suppression unit 41 is only located above the gap 23 and above the electrode finger 22 and does not include the part located above the bus bar 21. In this embodiment, the suppression unit is embedded in the passivation layer. Compared with the scheme where the suppression unit is located above the passivation layer (i.e., the scheme of Embodiment 1), the part embedded in the passivation layer can play a better role in suppressing the spurious mode. However, when adopting the embedded suppression unit structure, it is necessary to comprehensively consider the influence of the thickness of the passivation layer and the thickness of the suppression layer on the performance of the resonator. For example, when the part of the suppression unit embedded in the suppression layer is completely embedded in the passivation layer, the suppression layer needs to have a smaller thickness on the premise of satisfying good transverse mode suppression, otherwise the overall thickness of the passivation layer is relatively high, which will cause unnecessary loss to the working performance of the resonator.

[0105] Furthermore, the thickness of the portion of the suppression unit 41 located above the gap 23 is smaller than the thickness of the portion of the suppression unit 41 located above the electrode finger 22 (eg Figure 19 h12>h11), or the thickness of the portion of the suppression unit 41 located above the gap 23 is equal to the thickness of the portion of the suppression unit 41 located above the electrode finger 22 (as shown in Figure 17 and Figure 18 By thickening the portion of the suppression unit 41 located above the electrode finger 22 (compare Figure 18 and Figure 19 ) setting can further improve the lateral mode suppression effect and energy confinement effect, but it will also increase additional process steps or costs accordingly. Therefore, it should be selected according to actual needs during application.

[0106] The resonator with a lateral mode suppression structure of this embodiment flexibly sets the positional relationship between the suppression unit and the passivation layer based on the resonator structure of the first embodiment, thereby specifically adjusting the performance parameters of the resonator to meet the needs of multiple application scenarios.

[0107] Embodiment 3

[0108] This embodiment provides a resonator with a transverse mode suppression structure. The difference between this embodiment and the first and second embodiments is that the suppression unit in the resonator described in the first and second embodiments does not have a blind slot or a through slot, while the suppression unit in the resonator of this embodiment has a blind slot or a through slot. Figures 19 to 22 The resonator includes a piezoelectric substrate 10, an electrode layer 20, and a passivation layer 30 (please refer to Figure 4 ) and the suppression layer 40 (please refer to Figure 4 ).

[0109] As an example, please refer to the figure, the portion of the suppression unit 41 located above the gap 23 has at least one blind groove 411 and / or at least one through groove 412, the blind groove 411 opens from a side of the suppression unit 41 toward the piezoelectric substrate 10 and / or a side away from the piezoelectric substrate 10 and extends vertically, and the through groove 412 opens from a side of the suppression unit 41 away from the piezoelectric substrate 10 and exposes at least a portion of at least one of the electrode fingers 22.

[0110] like Figure 20As shown, the part of the suppression unit 41 above the gap 23 has at least two blind slots 411, and the two blind slots 411 are spaced apart in the first direction and the two blind slots 411 open from different faces of the suppression unit 41 respectively. The setting of the blind slots 411 can be designed in detail for the specific structure of the part of the suppression unit 41 above the gap 23 (even the part above the electrode finger 22) to specifically change the effects of the local structure on lateral suppression and energy limitation, so as to adaptively adjust the performance parameters of the resonator.

[0111] As Figure 21 shown, the part of the suppression unit 41 above the gap 23 has a plurality of through slots 412, and the plurality of through slots 412 are spaced apart in the second direction and each through slot 412 exposes at least a part of an electrode finger 22. After the suppression layer 40 is fabricated, patterning the suppression layer 40 can obtain the above structure. The above structure can not only control the acoustic wave propagation speed in the edge region of the electrode finger, but also control the acoustic wave propagation speed in the gap region, thereby reducing scattering loss and limiting energy leakage to improve the performance of the resonator.

[0112] As Figure 22 shown, the part of the suppression unit 41 above the gap 23 has a through slot 412, the through slot 412 occupies nearly half of the area of the suppression unit 41 above the gap 23 and is triangular, and the setting of the through slot 412 makes the suppression unit 41 in a tapered shape, so that the energy transmitted through the interdigital electrode is concentrated in the electrode finger 22 region to reduce energy loss, thereby further improving the performance of the resonator.

[0113] The resonator with a lateral mode suppression structure in this embodiment further improves the working performance of the resonator by diversifying the design of the structure of the suppression unit on the basis of the resonator structures described in Embodiment 1 and Embodiment 2.

[0114] Embodiment 4

[0115] This embodiment provides a resonator with a lateral mode suppression structure. The difference between this embodiment and Embodiment 1 and Embodiment 2 is that: the part of the suppression unit in the resonators described in Embodiment 1 and Embodiment 2 above the gap and above the electrode finger is an integral structure, while the part of the suppression unit in the resonator of this embodiment above the gap and above the electrode finger includes a plurality of separately arranged suppression blocks. Please refer to FIGS. 23 to Figure 27 , this resonator includes a piezoelectric substrate 10, an electrode layer 20, a passivation layer 30 (please refer to Figure 4 ) and a suppression layer 40 (please refer to Figure 4 ).

[0116] As an example, the portion of the suppression unit 41 located above the gap 23 and the electrode fingers 22 includes a plurality of suppression blocks 413 spaced apart in the second direction, and at least one of the suppression blocks 413 partially overlaps with the electrode fingers 22 on different sides of the suppression block 413.

[0117] As an example, as Figure 23 and Figure 24 shown, the sizes (length, width, and thickness) of each of the suppression blocks 413 are the same and the suppression blocks 413 in the same suppression unit 41 are aligned, or, as Figure 25 and Figure 26 shown, the sizes of each of the suppression blocks 413 are different but the plurality of suppression blocks 413 are symmetrically distributed about the central axis of the resonator in the second direction, and the two suppression units 41 are symmetrically distributed about the central axis of the resonator in the first direction. For example, the length of the suppression block 413 is proportional to the distance of the suppression block 413 from the central position;

[0118] As an example, as Figures 23 to 25 shown, the suppression unit 41 includes a plurality of first suppression blocks 413a, and the first suppression blocks 413a extend above the gap 23 in the first direction and partially overlap with the electrode fingers 22 on different sides of the first suppression blocks 413a

[0119] As an example, as Figure 24 and Figure 25 shown, the suppression unit 41 further includes a plurality of second suppression blocks 413b, and the second suppression blocks 413b extend above the electrode fingers 22 on the same side as the second suppression blocks 413b in the first direction. The plurality of first suppression blocks 413a and the plurality of second suppression blocks 413b in the same suppression unit 41 are alternately arranged, and the first suppression blocks 413a and the second suppression blocks 413b in different suppression units 41 are arranged opposite to each other. The first suppression blocks 413a and the second suppression blocks 413b have the same morphology (as Figure 24 shown), or, the first suppression blocks 413a and the second suppression blocks 413b (as Figure 25 shown) have different morphologies.

[0120] The resonator with a transverse mode suppression structure in this embodiment further improves the working performance of the resonator by diversifying the structure of the suppression unit on the basis of the resonator structures described in Embodiment 1 and Embodiment 2.

[0121] Embodiment 5

[0122] The present invention also provides a method for manufacturing a resonator with a lateral mode suppression structure. This manufacturing method is used to manufacture the resonator structures described in Embodiments 1 to 4 and other suitable resonator structures. The manufacturing method includes the following steps:

[0123] Provide a piezoelectric substrate;

[0124] Form an electrode layer above the piezoelectric substrate. The electrode layer includes two interdigital electrodes disposed opposite to each other in a first direction. Each interdigital electrode includes a bus bar and a plurality of electrode fingers. The plurality of electrode fingers in the same interdigital electrode are spaced apart in a second direction and are all connected to the bus bar. There is a gap between the electrode fingers and the bus bar in different interdigital electrodes. The second direction is perpendicular to the first direction;

[0125] Form a passivation layer above the piezoelectric substrate. The passivation layer is embedded between the two interdigital electrodes in the first direction and covers the electrode fingers and the gap;

[0126] Form a suppression layer above the piezoelectric substrate. The suppression layer includes two suppression units disposed opposite to each other in the first direction. Each suppression unit is respectively connected to a bus bar and extends along the first direction to cover the gap and partially overlap at least one electrode finger connected to the other bus bar.

[0127] The manufacturing method of the resonator with a lateral mode suppression structure in this embodiment can effectively improve the performance of the resonator structure without special high-resolution processes. The process steps are simple and the cost is low, and large-scale production of high-performance resonators can be achieved.

[0128] In summary, for the resonator with a lateral mode suppression structure of the present invention, the additional suppression layer structure can suppress the lateral mode through the energy confinement effect while improving the quality factor of the resonator. It is applicable to a variety of resonator structures and a wide frequency range, and the manufacturing process does not require special high-resolution processes, with a simple structure and a mature manufacturing process. And after further improving and optimizing the suppression layer structure, the piston mode effect can be achieved without using a hammerhead structure or a selective disassembly method, reducing the scattering loss. In addition, the material selection of the suppression layer enables the suppression layer to act as a heat sink due to its good thermal conductivity in addition to the lateral mode suppression effect, which can improve the durability and linearity of the resonator, and improve the working stability and service life of the resonator. The manufacturing method of the resonator with a lateral mode suppression structure of the present invention can effectively improve the performance of the resonator structure without special high-resolution processes. The process steps are simple and the cost is low, and large-scale production of high-performance resonators can be achieved. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0129] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A resonator with a transverse mode suppression structure, characterized in that Comprising: A piezoelectric substrate; An electrode layer, located above the piezoelectric substrate, the electrode layer includes two interdigital electrodes disposed opposite to each other in a first direction, each interdigital electrode includes a bus bar and a plurality of electrode fingers, the plurality of electrode fingers in the same interdigital electrode are spaced apart in a second direction and are all connected to the bus bar, and there is a gap between the electrode fingers and the bus bar in different interdigital electrodes, the second direction is perpendicular to the first direction; A passivation layer, located above the piezoelectric substrate, the passivation layer is embedded between the two interdigital electrodes in the first direction and covers the electrode fingers and the gap; A suppression layer, located above the piezoelectric substrate, the suppression layer includes two suppression units disposed opposite to each other in the first direction, each suppression unit is respectively connected to a bus bar and extends along the first direction to cover the gap and partially overlap at least one electrode finger on different sides of the suppression unit.

2. The resonator with a lateral mode suppression structure according to claim 1, wherein: When the distance between two adjacent electrode fingers in the same interdigital electrode is λ, the width range of the partial overlap between the suppression unit and the electrode finger is 0 to 1.0λ, and / or, the thickness range of the part of the suppression unit located above the gap and above the electrode finger is 1 to 100 nm.

3. The resonator with a lateral mode suppression structure according to claim 1, wherein: The suppression unit is connected to the side of the bus bar away from the piezoelectric substrate and extends above the passivation layer.

4. The resonator with a lateral mode suppression structure according to claim 3, characterized in that: The thickness of the part of the suppression unit located above the bus bar is greater than or equal to the thickness of the part of the suppression unit located above the passivation layer.

5. The resonator with a lateral mode suppression structure according to claim 3, characterized in that: The suppression unit is also vertically embedded in the passivation layer, and the part of the suppression unit vertically embedded in the passivation layer is located above the gap.

6. The resonator with a lateral mode suppression structure according to claim 1, characterized in that: The suppression unit is connected to the side surface of the bus bar and is embedded in the passivation layer in the first direction.

7. The resonator with a lateral mode suppression structure according to claim 1, characterized in that: The part of the suppression unit located above the gap has at least one blind groove and / or at least one through groove, the blind groove opens from the side of the suppression unit facing the piezoelectric substrate and / or the side facing away from the piezoelectric substrate and extends vertically, and the through groove opens from the side of the suppression unit facing away from the piezoelectric substrate and exposes at least a part of at least one electrode finger.

8. The resonator with a lateral mode suppression structure according to claim 1, characterized in that: The passivation layer has a groove, the vertical projection of the groove is located between the vertical projections of the two suppression units, and the part of the passivation layer surrounding the groove forms a raised frame.

9. The resonator with a lateral mode suppression structure according to claim 1, characterized in that: The part of the suppression unit located above the gap and above the electrode finger includes a plurality of suppression blocks spaced apart in the second direction, and at least one suppression block partially overlaps with the electrode finger on a different side of the suppression block.

10. The resonator with a lateral mode suppression structure according to claim 9, characterized in that: The suppression unit includes a plurality of first suppression blocks, the first suppression blocks extend above the gap in the first direction and partially overlap with the electrode fingers on different sides of the first suppression blocks.

11. The resonator with a lateral mode suppression structure according to claim 10, characterized in that: The suppression unit further includes a plurality of second suppression blocks, the second suppression blocks extend above the electrode fingers on the same side as the second suppression blocks in the first direction, the plurality of first suppression blocks and the plurality of second suppression blocks in the same suppression unit are alternately arranged, the first suppression blocks and the second suppression blocks in different suppression units are oppositely arranged, and the morphologies of the first suppression blocks and the second suppression blocks are the same or different.

12. The resonator with a lateral mode suppression structure according to claim 1, characterized in that: The interdigital electrode further includes a plurality of dummy fingers connected to the bus bar. The plurality of dummy fingers in the same interdigital electrode are alternately and spaced apart from a plurality of electrode fingers and the dummy fingers are embedded in the gap. There is a preset distance between the dummy fingers and the electrode fingers in different interdigital electrodes.

13. The resonator with a lateral mode suppression structure according to claim 1, wherein: The material of the suppression layer includes at least one of a metal material and a high-density dielectric material. The metal material includes at least one of Al, Ti, Cu, Pt, and Au. The high-density dielectric material includes at least one of Ta2O5, HfO2, and BaTiO3.

14. A method for manufacturing a resonator with a transverse mode suppression structure, characterized in that, comprising the following steps: providing a piezoelectric substrate; forming an electrode layer above the piezoelectric substrate, the electrode layer including two interdigital electrodes oppositely arranged in a first direction. Each interdigital electrode includes a bus bar and a plurality of electrode fingers. The plurality of electrode fingers in the same interdigital electrode are spaced apart in a second direction and are all connected to the bus bar. There is a gap between the electrode fingers and the bus bar in different interdigital electrodes. The second direction is perpendicular to the first direction; forming a passivation layer above the piezoelectric substrate, the passivation layer being embedded between the two interdigital electrodes in the first direction and covering the electrode fingers and the gap; forming a suppression layer above the piezoelectric substrate, the suppression layer including two suppression units oppositely arranged in a first direction. Each suppression unit is respectively connected to a bus bar and extends along the first direction to cover the gap and partially overlap at least one electrode finger connected to the other bus bar.

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