Pure acoustic hybrid filter structure and preparation method thereof

Abstract

According to the pure acoustic hybrid filter structure and the preparation method thereof provided by the invention, the resonators are arranged on different resonance units according to actual needs, and the mode can fully integrate the advantages of different resonance units; independent design of parameters of a resonator series arm and a resonator parallel arm in an electrical topological structure of a pure acoustic hybrid filter structure is realized, effective regulation and control of resonant frequency of target resonance, typical line width of a device, piezoelectric transduction level, out-of-band clutter and the like are achieved, the preparation difficulty of the device is effectively reduced, excitation of a stray mode is inhibited or weakened, and the performance of the device is improved. The design flexibility of the acoustic filter is improved, and device-level integration is realized; in addition, the adjustable bandwidth can be realized without adding external electrical elements, so that flat and low-insertion-loss filter passband response is obtained, the transmission efficiency of communication signals in the passband is improved, and the filter is not limited by line width and meets various application requirements.

Description

Technical Field

[0001] The invention belongs to the field of microelectronic technology, and in particular relates to a pure acoustic hybrid filter structure and a preparation method thereof. Background Art

[0002] With the development of communication technology and the enrichment of application scenarios, 3GHz and lower frequency bands are widely used in communication, data transmission, Internet of Things and other fields, and the application frequency band is developing in the direction of high frequency and large bandwidth. For surface acoustic wave devices, the increase in application frequency is undoubtedly faced with the miniaturization of typical line width and size. On the one hand, by developing preparation technology and processes with smaller line width, the line width can be reduced to obtain higher frequency devices, but at the same time there is a hidden danger of reduced device stability, and the approach of relying on scale miniaturization to achieve performance improvement may encounter bottlenecks that are difficult to overcome in physical principles; on the other hand, higher frequency acoustic wave modes can be developed to study and design high frequency devices. In addition, in the post-Moore era of the semiconductor industry, the concept of integration has been proposed, and devices with various functions can be heterogeneously integrated on-chip or developed into chips to achieve performance improvement of functional devices.

[0003] The hybrid filter structure currently realized is based on the integration of acoustic filter devices and electrical components, such as capacitors and inductors, which can realize the regulation of filter bandwidth, increase or decrease the bandwidth of the filter passband, etc. However, in the actual device production and preparation, the problem with using capacitors and inductors is that the quality factor of such electrical components is low, which may lead to increased signal loss in the passband of the filter device when achieving other preset performance. Summary of the invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a pure acoustic hybrid filter structure and a preparation method thereof, so as to solve the problem that the hybrid filter structure based on the integration of acoustic filter devices and electrical components in the prior art has a low quality factor of the electrical components, which may lead to increased signal loss in the passband of the filter device when achieving other preset performances.

[0005] To achieve the above-mentioned object and other related objects, the present invention provides a pure acoustic hybrid filter structure, the pure acoustic hybrid filter structure comprising: a plurality of resonators, wherein the plurality of resonators are combined to form an electrical topology structure, wherein the electrical topology structure comprises a resonator series arm and a resonator parallel arm;

[0006] The pure acoustic hybrid filter structure includes at least two different resonance units in terms of physical structure, and all the resonators are respectively arranged on all the different resonance units according to preset requirements;

[0007] The resonance unit includes a support substrate, a piezoelectric film and interdigital electrodes in sequence along the thickness direction, wherein the interdigital electrodes on all different resonance units are electrically connected through block electrodes to realize electrical connection of all resonators in the electrical topology structure, and the sound velocity of the support substrate is not less than the sound velocity of the highest sound velocity mode in the target sound wave mode;

[0008] Elements characterizing the differences of the resonance units include: the support substrates are different and / or the piezoelectric films are different and / or the interdigitated electrodes are different. Here, the width of the electrode fingers in the interdigitated electrodes is not used as an element characterizing the differences of the resonance units.

[0009] Optionally, the different supporting substrates include different types of materials of the supporting substrates and / or different material cuts of the supporting substrates and / or different thicknesses of the supporting substrates; the different piezoelectric films include different types of materials of the piezoelectric films and / or different thicknesses of the piezoelectric films and / or different material cuts of the piezoelectric films; the different interdigitated electrodes include different types of materials of the interdigitated electrodes and / or different thicknesses of the interdigitated electrodes and / or different arrangement directions of the electrode fingers in the interdigitated electrodes.

[0010] Optionally, at least one of the resonance units further includes a dielectric layer, which is disposed between the supporting substrate and the piezoelectric film or between the piezoelectric film and the interdigitated electrodes; or the supporting substrate of at least one of the resonance units is provided with a blind groove, and a corresponding portion of the thickness of the piezoelectric film is embedded in the blind groove.

[0011] Furthermore, the material of the dielectric layer is one of silicon oxide, carbon-doped silicon oxide, silicon nitride and aluminum nitride.

[0012] Optionally, the material of the piezoelectric film is one of lithium niobate, lithium tantalate, quartz, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, lead magnesium niobate titanate, gallium nitride, gallium oxide, and gallium arsenide; the material of the supporting substrate is one of silicon carbide, silicon, sapphire, quartz, diamond, diamond-like carbon, gallium nitride, boron carbide, boron nitride, and aluminum nitride.

[0013] Optionally, all the different resonance units are located in a horizontal plane at the same height or the surface height difference of all the different resonance units is within a hundred nanometer level.

[0014] Optionally, all the different resonance units are arranged on a same supporting substrate; or all the different resonance units are arranged on two or more different supporting substrates, and all the different resonance units are connected together on a substrate.

[0015] Furthermore, when all the different resonance units are arranged on more than two different support substrates, and all the different resonance units are connected together on one substrate, a raising layer is provided on the substrate to ensure that all the different resonance units are located in a horizontal plane at the same height.

[0016] The present invention also provides a method for preparing a pure acoustic hybrid filter structure, the preparation method comprising:

[0017] At least two different resonance units are prepared by a transfer method; wherein, the multiple resonators included in the pure acoustic hybrid filter structure are respectively prepared on all different resonance units according to preset needs, each of the resonance units includes a supporting substrate, a piezoelectric film and a forked electrode in sequence along the thickness direction, and the sound velocity of the supporting substrate is not less than the sound velocity of the highest sound velocity mode in the target sound wave mode, and the elements characterizing the differences of the resonance units include: the supporting substrates are different and / or the piezoelectric films are different and / or the forked electrodes are different, and the width of the electrode fingers in the forked electrodes is not used as an element characterizing the differences of the resonance units;

[0018] Block electrodes are formed on the interdigital electrodes of all the different resonance units to electrically connect the interdigital electrodes of all the resonators to form an electrical topology structure, wherein the electrical topology structure includes a resonator series arm and a resonator parallel arm.

[0019] Optionally, all the different resonance units are prepared on two or more different support substrates, and the step of preparing at least two different resonance units by a transfer method includes:

[0020] preparing the resonance units located on different support substrates respectively;

[0021] A substrate is provided, and the resonance units located on different support substrates are arranged in contact with each other in sequence through all the support substrates and fixed on the substrate.

[0022] Furthermore, when the heights of the resonance units on different supporting substrates are inconsistent, a raising layer is provided on the substrate to ensure that the resonance units on different supporting substrates are located in a horizontal plane at the same height after being fixed on the substrate.

[0023] Furthermore, at least two different resonance units are prepared on the same support substrate, and the step of preparing at least two different resonance units located on the same support substrate by a transfer method includes:

[0024] S1. providing a substrate, wherein the substrate comprises, from bottom to top, a stacked substrate layer, a separation layer and a piezoelectric film layer;

[0025] S2, fixing the supporting substrate on the piezoelectric film layer, wherein the size of the supporting substrate is larger than the size of the piezoelectric film layer;

[0026] S3, separating the base layer from the piezoelectric film layer based on the separation layer;

[0027] S4, forming corresponding interdigital electrodes on the piezoelectric film layer to obtain an intermediate structure, which realizes the preparation of a resonance unit;

[0028] S5, taking steps S1 to S4 as a cycle unit for preparing each resonance unit, and when preparing the next resonance unit, using the intermediate structure obtained by preparing the previous resonance unit as the supporting substrate in the preparation process of the next resonance unit, and when fixing the supporting substrate on the piezoelectric film layer in preparing the next resonance unit, using the blank area of ​​the supporting substrate in the intermediate structure obtained by preparing the previous resonance unit;

[0029] S6. Repeat step S5 until a required number of different resonance units are formed on the supporting substrate.

[0030] Furthermore, at least two different resonance units are prepared on the same support substrate, and the step of preparing at least two different resonance units located on the same support substrate by a transfer method includes:

[0031] S1, providing a first substrate, wherein the first substrate comprises, from bottom to top, a first substrate layer, a first separation layer, and a first piezoelectric film layer stacked one on top of the other;

[0032] S2, fixing the supporting substrate on the first piezoelectric film layer, wherein the size of the supporting substrate is larger than the size of the first piezoelectric film layer;

[0033] S3, separating the first substrate layer from the first piezoelectric film layer based on the first separation layer;

[0034] S4, forming corresponding interdigital electrodes on the first piezoelectric film layer to obtain a first intermediate structure, wherein the first intermediate structure realizes the preparation of a resonance unit;

[0035] S5, providing a second substrate, wherein the second substrate comprises, from bottom to top, a stacked second substrate layer, a second separation layer, and a second piezoelectric film layer;

[0036] S6, forming corresponding interdigital electrodes on the second piezoelectric film layer, and separating the second substrate layer from the second piezoelectric film layer based on the second separation layer to obtain a second intermediate structure;

[0037] S7, fixing the second intermediate structure on the first intermediate structure;

[0038] S8. Take steps S5 to S7 as a circulation unit for preparing each different second intermediate structure and fixing it on the blank area of ​​the supporting substrate of the first intermediate structure, until a required number of different resonance units are formed on the supporting substrate.

[0039] As described above, the pure acoustic hybrid filter structure and preparation method of the present invention set the resonator on different resonance units according to actual needs, that is, the resonators set on the same resonance unit are the same, and the resonators set on different resonance units are different. This method can fully integrate the advantages of different resonance units, and realize the independent design of the parameters of the resonator series arm and the resonator parallel arm in the electrical topology structure of the pure acoustic hybrid filter structure, so as to achieve effective regulation of the resonant frequency of the target resonance, the typical line width of the device, the piezoelectric transduction level and out-of-band noise, etc., effectively reduce the difficulty of device preparation, suppress or weaken the excitation of spurious modes, improve the design flexibility of the acoustic filter, and realize device-level integration; in addition, adjustable bandwidth can be achieved without the addition of external electrical components, thereby obtaining a flat, low insertion loss filter passband response, improving the transmission efficiency of communication signals within the passband, and is not constrained by line width, meeting various application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 and Figure 2 Shown are two schematic diagrams of electrical topologies of the purely acoustic hybrid filter structure of the present invention.

[0041] Figures 3 to 10 Shown is a schematic cross-sectional view of the structure of a purely acoustic hybrid filter of the present invention.

[0042] Figures 11 to 13 A schematic cross-sectional view showing the steps in a method for preparing a pure acoustic hybrid filter structure according to a first example of the present invention.

[0043] Figures 14 to 22 A schematic cross-sectional view showing the steps in a method for preparing a pure acoustic hybrid filter structure according to a second example of the present invention.

[0044] Figure 23 to Figure 33 A schematic cross-sectional view showing the steps in a method for preparing a pure acoustic hybrid filter structure according to a third example of the present invention.

[0045] Fig.34 Shown are schematic diagrams of electrical topological structures of filter structures of comparative examples 1 and 3.

[0046] Fig.35Shown is a frequency response curve of the resonator in the filter structure of comparative example 1 and a passband response curve of the corresponding filter structure.

[0047] Fig.36 Shown is a schematic diagram of the electrical topology of the pure acoustic hybrid filter structure of Experimental Example 1 of the present invention.

[0048] Fig.37 Shown are the frequency response curve of the resonator in the pure acoustic hybrid filter structure of Experimental Example 1 and the passband response curve of the corresponding pure acoustic hybrid filter structure.

[0049] Fig.38 Shown is a schematic diagram of the electrical topology of the filter structure of comparative example 2.

[0050] Fig.39 Shown is a frequency response curve of the resonator in the filter structure of comparative example 2 and a passband response curve of the corresponding filter structure.

[0051] Fig.40 Shown is a schematic diagram of the electrical topology of the pure acoustic hybrid filter structure of Experimental Example 2 of the present invention.

[0052] Fig.41 Shown are the frequency response curve of the resonator in the pure acoustic hybrid filter structure of Experimental Example 2 and the passband response curve of the corresponding pure acoustic hybrid filter structure.

[0053] Fig.42 Shown is the frequency response curve of the resonator in the filter structure of comparative example 3 and the passband response curve of the corresponding filter structure.

[0054] Fig.43 Shown is a schematic diagram of the electrical topology of the pure acoustic hybrid filter structure of Experimental Example 3 of the present invention.

[0055] Fig.44 Shown are the frequency response curve of the resonator in the pure acoustic hybrid filter structure of Experimental Example 3 and the passband response curve of the corresponding pure acoustic hybrid filter structure.

[0056] Fig.45 Shown are three frequency response curves of the resonator in the pure acoustic hybrid filter structure of Experimental Example 3 and three passband response curves of the corresponding pure acoustic hybrid filter structure.

[0057] Component number description

[0058] 1 Purely acoustic hybrid filter structure

[0059] 10 Resonance Unit

[0060] 100 Support substrate

[0061] 101 Piezoelectric Film

[0062] 102 Interdigitated electrodes

[0063] 103 Block Electrode

[0064] 104 First resonance unit

[0065] 105 Second resonance unit

[0066] 11 Resonator

[0067] 12 Dielectric layer

[0068] 13 Blind slot

[0069] 14 substrate

[0070] 15 Raised layer

[0071] 2 Electrical topology

[0072] 20 Resonator series arms

[0073] 21 Resonator parallel arm

[0074] 30 base

[0075] 300 Base layer

[0076] 301 Separation Layer

[0077] 302 Piezoelectric film layer

[0078] 303 Intermediate structure

[0079] 31 First Base

[0080] 310 First base layer

[0081] 311 First separation layer

[0082] 312 first piezoelectric film layer

[0083] 313 First intermediate structure

[0084] 314 Second intermediate structure

[0085] 32 Second Base

[0086] 320 Second base layer

[0087] 321 Second separation layer

[0088] 322 second piezoelectric film layer

[0089] 323 Second intermediate structure

[0090] 33 First device structure

[0091] 34 Second device structure DETAILED DESCRIPTION

[0092] 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.

[0093] 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.

[0094] For convenience of description, spatial relational 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 spatial relational terms are intended to include other orientations of the device in use or operation in addition to the orientation depicted in the drawings, and 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, so that the first and second features may not be in direct contact. In addition, when a layer is referred to as being "between" two layers, it may be between the two layers.

[0095] See also Figures 1 to 44 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 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.

[0096] like Figures 1 to 10 As shown, this embodiment provides a pure acoustic hybrid filter structure, the pure acoustic hybrid filter structure 1 comprises: a plurality of resonators 11, and a plurality of the resonators 11 are combined to form an electrical topology structure 2, the electrical topology structure 2 comprises a resonator series arm 20 and a resonator parallel arm 21;

[0097] The pure acoustic hybrid filter structure 1 includes at least two different resonance units 10 in terms of physical structure, and all the resonators 11 are respectively arranged on all the different resonance units 10 according to preset requirements;

[0098] The resonance unit 10 includes a support substrate 100, a piezoelectric film 101 and an interdigital electrode 102 in sequence along the thickness direction, wherein the interdigital electrodes 102 on all different resonance units 10 are electrically connected through a block electrode 103 to realize the electrical connection of all the resonators 11 in the electrical topology structure 2, and the sound velocity of the support substrate 100 is not less than the sound velocity of the highest sound velocity mode in the target sound wave mode;

[0099] Elements that characterize the differences of the resonance unit 10 include: the support substrate 100 is different and / or the piezoelectric film 101 is different and / or the interdigitated electrodes 102 are different. Here, the width of the electrode fingers in the interdigitated electrodes 102 is not used as an element that characterizes the differences of the resonance unit 10.

[0100] The pure acoustic hybrid filter structure of this embodiment sets the resonators on different resonance units according to actual needs, that is, the resonators set on the same resonance unit are the same, and the resonators set on different resonance units are different. This method can fully integrate the advantages of different resonance units, and realize the independent design of the parameters of the resonator series arm and the resonator parallel arm in the electrical topology structure of the pure acoustic hybrid filter structure, so as to achieve effective regulation of the resonant frequency of the target resonance, the typical line width of the device, the piezoelectric transduction level and the out-of-band noise, etc., effectively reduce the difficulty of device preparation, suppress or weaken the excitation of spurious modes, improve the design flexibility of the acoustic filter, and realize device-level integration; in addition, adjustable bandwidth can be achieved without adding external electrical components, thereby obtaining a flat, low insertion loss filter passband response, improving the transmission efficiency of communication signals in the passband, and is not constrained by line width, meeting various application requirements.

[0101] It should be noted here that in this embodiment, the width of the electrode fingers in the forked electrode is not used as an element to characterize the different resonance units. That is to say, the width of the electrode fingers of the forked electrodes of multiple resonators on the same resonance unit may be the same or different. The width of the electrode fingers in the forked electrode can realize the regulation of the resonance frequency of the resonator. The wider the electrode finger width, the lower the resonance frequency, and vice versa. Therefore, the resonance frequencies of multiple resonators on the same resonance unit may be the same or different, and the specific setting is based on actual needs. In addition, the number of resonators set on the same resonance unit is selected according to actual needs, and is not overly limited in this embodiment.

[0102] As an example, in the electrical topology structure 2 of the pure acoustic hybrid filter structure 1, there is one resonator series arm 20 and at least one resonator parallel arm 21, for example Figure 1 and Figure 2There is one resonator series arm 20 and three resonator parallel arms 21. In addition, the number of resonators 11 on the resonator series arm 20 and the number of resonators 11 on the resonator parallel arms 21 are not excessively limited, for example Figure 1 The number of resonators 11 on the middle resonator series arm 20 is 4, and the number of resonators 11 on the resonator parallel arm 21 is 1. Figure 2 There is a resonator parallel arm 21 with two resonators 11. Furthermore, the connection position of the resonator parallel arm 21 on the resonator series arm 20 is not excessively limited and can be set according to actual needs.

[0103] As an example, the acoustic wave target mode of the resonator 11 in the pure acoustic hybrid filter structure 1 may be a horizontal shear wave, a longitudinal leakage wave, a longitudinal shear wave, and the like.

[0104] As an example, the difference of the supporting substrate 100 in the elements characterizing the difference of the resonance unit 10 mainly includes: at least one of the three elements of the material type of the supporting substrate 100, the material cut type of the supporting substrate 100 and the thickness of the supporting substrate 100 is different, which can be identified as the supporting substrate 100 is different, that is, the material type of the supporting substrate 100 is different and / or the material cut type of the supporting substrate 100 is different and / or the thickness of the supporting substrate 100 is different, which can be identified as the supporting substrate 100 is different; the difference of the piezoelectric film 101 in the elements characterizing the difference of the resonance unit 10 mainly includes: at least one of the three elements of the material type of the piezoelectric film 101, the material cut type of the piezoelectric film 101 and the thickness of the piezoelectric film 101 is different. The piezoelectric films 101 are the same, that is, the piezoelectric films 101 have different material types and / or the thicknesses of the piezoelectric films 101 are different and / or the material cut types of the piezoelectric films 101 are different, that is, the piezoelectric films 101 are different; the differences in the interdigitated electrodes 102 among the elements that characterize the different resonance units 10 mainly include: at least one of the three elements, namely, the material types of the interdigitated electrodes 102, the thicknesses of the interdigitated electrodes 102 and the arrangement directions of the electrode fingers in the interdigitated electrodes 102 is different, that is, the interdigitated electrodes 102 are different in material types and / or the thicknesses of the interdigitated electrodes 102 and / or the arrangement directions of the electrode fingers in the interdigitated electrodes 102 are different, that is, the interdigitated electrodes 102 are different.

[0105] As a preferred example, the surface height difference of all the different resonant units 10 is within the order of hundreds of nanometers. More preferably, all the different resonant units 10 are located in a horizontal plane at the same height. When the surface height difference of all the resonant units 10 is within the order of hundreds of nanometers or even located in a horizontal plane at the same height, it is convenient for the block electrode 103 to electrically connect all the resonators 11 on all the resonant units 10, thereby improving the reliability of the electrical connection. Based on the different characterization definitions of the resonant units 10 described above, the arrangement of all the resonant units 10 in the pure acoustic hybrid filter structure 1 of this embodiment may be arranged on the same supporting substrate 100 according to actual needs, such as Figures 3 to 8 In the pure acoustic hybrid filter structure 1, all the resonant units 10 are arranged on the same supporting substrate 100. Figures 3 to 7 The pure acoustic hybrid filter structure 1 is provided with two resonant units 10 and fixed together on the same supporting substrate 100. Figure 8 The pure acoustic hybrid filter structure 1 is provided with three resonant units 10 and fixed together on the same supporting substrate 100; in addition, all the resonant units 10 in the pure acoustic hybrid filter structure 1 of this embodiment may also be provided on two or more different supporting substrates 100 according to actual needs, for example Fig. 9 and Fig.10 In the pure acoustic hybrid filter structure 1, all the resonant units 10 are arranged on two different supporting substrates 100 to form a first device structure 33 and a second device structure 34. At this time, the first device structure 33 and the second device structure 34 arranged on two different supporting substrates 100 are connected to a substrate 14 through the two different supporting substrates 100 to achieve the integration of all the resonant units 10. Of course, they can also be arranged on three or more different supporting substrates 100, and the specific arrangement is carried out according to actual needs. It should be noted that the structure arranged on different supporting substrates 100 is defined as a device structure here, for example Fig. 9 and Fig.10 The first device structure 33 and the second device structure 34 in the embodiment may be composed of only one resonance unit 10, or may be composed of two or more different resonance units 10, for example Fig. 9 The first device structure 33 in the embodiment may be composed of Figure 8 The three different resonant units 10 constitute or Figure 7 It is composed of two different resonant units 10.

[0106] As mentioned above, it is preferred that all the different resonant units 10 are located in a horizontal plane at the same height, so when the thickness of the resonant units 10 in the pure acoustic hybrid filter structure 1 is inconsistent, some auxiliary layers can be used to achieve a high degree of consistency. For example, when all the resonant units 10 in the pure acoustic hybrid filter structure 1 are arranged on the same supporting substrate 100, the reason for the different thicknesses of the resonant units 10 may be that the thickness of the piezoelectric film 101 and / or the thickness of the interdigital electrodes 102 are different, for example Figure 3 The difference is caused by the different thicknesses of the piezoelectric films 101 of the two resonance units 10. The thickness of all the resonance units 10 can be made consistent by providing a dielectric layer 12 between the support substrate 100 and the piezoelectric film 101 of the resonance unit 10 with a smaller thickness or between the piezoelectric film 101 and the interdigital electrode 102. Figure 4 That is, a dielectric layer 12 is arranged between the supporting substrate 100 and the piezoelectric film 101 to make the thickness of the two resonant units 10 consistent. At this time, the dielectric layer 12 plays a role in adjusting the thickness of the resonant unit 10, so the material selection of the dielectric layer 12 at this time will not affect the material of the resonator performance, but sometimes the dielectric layer 12 is needed to adjust the resonator performance. At this time, the dielectric layer 12 plays a role in adjusting the performance of the resonator device and adjusting the thickness of the resonant unit 10. At this time, the material selection of the dielectric layer 12 needs to take into account the functions of both. For example, the commonly selected material is one of silicon oxide, carbon-doped silicon oxide, silicon nitride and aluminum nitride; Figure 5 As shown, blind grooves 13 can also be provided on the surface of the support substrate 100 of the thicker resonance unit 10, and part of the thickness of the piezoelectric film 101 is embedded in the blind grooves 13 to make the thickness of all the resonance units 10 consistent. When all the resonance units 10 in the pure acoustic hybrid filter structure 1 are provided on two or more different support substrates 100, and all the different resonance units 10 are connected together on one substrate 14, as shown in FIG. Fig.10 The first device structure 33 and the second device structure 34 in the embodiment can be provided with a cushioning layer 15 between the device structure with a smaller thickness and the substrate 14 so that all the device structures are located in a horizontal plane at the same height, such as Fig.10 A padding layer 15 is disposed between the second device structure 34 and the substrate 14. The material of the padding layer is preferably various organic photoresists, such as benzocyclobutene or polyimide, etc. The material of the substrate 14 is preferably aluminum oxide or glass, etc.

[0107] As an example, the material of the piezoelectric film 101 can be selected from one of lithium niobate, lithium tantalate, quartz, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, lead magnesium niobate titanate, gallium nitride, gallium oxide, and gallium arsenide.

[0108] As an example, the material of the support substrate 100 can be selected from one of silicon carbide, silicon, sapphire, quartz, diamond, diamond-like carbon, gallium nitride, boron carbide, boron nitride, and aluminum nitride.

[0109] As an example, the material of the interdigital electrode 102 can be selected from any one of copper, silver, gold, aluminum, platinum, nickel, molybdenum, tungsten, chromium, and titanium, or an alloy thereof; the interdigital electrode 102 includes a single-layer interdigital electrode or a composite laminated interdigital electrode.

[0110] This embodiment also provides a method for preparing a pure acoustic hybrid filter structure, which is used to prepare the above-mentioned pure acoustic hybrid filter structure. The preparation method includes:

[0111] Step 1, preparing at least two different resonance units 10 by a transfer method; wherein, the plurality of resonators included in the pure acoustic hybrid filter structure are prepared on all the different resonance units 10 according to preset requirements, each of the resonance units 10 includes a supporting substrate 100, a piezoelectric film 101 and a forked electrode 102 in sequence along the thickness direction, and the sound velocity of the supporting substrate 100 is not less than the sound velocity of the highest sound velocity mode in the target sound wave mode, and the elements characterizing the differences of the resonance units 10 include: the supporting substrate 100 is different and / or the piezoelectric film 101 is different and / or the forked electrode 102 is different, and the width of the electrode finger in the forked electrode 102 is not used as an element characterizing the differences of the resonance units 10;

[0112] Step 2: forming a block electrode 103 on the interdigital electrodes 102 of all the different resonance units 10 to electrically connect the interdigital electrodes 102 of all the resonators 11 to form an electrical topology structure 2, wherein the electrical topology structure 2 includes a resonator series arm 20 and a resonator parallel arm 21.

[0113] The transfer method mentioned in this embodiment refers to the process of transferring one structure to the surface of another structure.

[0114] Based on the different characterization definitions of the resonance units 10 described above, all the resonance units 10 in the pure acoustic hybrid filter structure 1 of this embodiment may be arranged on two or more different support substrates 100 according to actual needs, for example Fig. 9 and Fig.10 In the pure acoustic hybrid filter structure 1, all the resonant units 10 are arranged on two different supporting substrates 100 to form a first device structure 33 and a second device structure 34. In this case, the steps of preparing at least two different resonant units 10 by transfer printing include:

[0115] First, the resonant units 10 located on different support substrates 100 are prepared respectively, for example, Fig.11 and Fig.12 The first device structure 33 and the second device structure 34; it should be noted here that the preparation process of the resonance unit 10 located on different supporting substrates 100 can be implemented by the existing conventional resonator preparation process; no excessive restrictions are made here.

[0116] Then, if Fig.13 As shown, a substrate 14 is provided, and the resonant units 10 (i.e., the first device structure 33 and the second device structure 34) located on different supporting substrates 100 are sequentially arranged in contact with each other through all the supporting substrates 100 and fixed on the substrate 14. In this step, when the heights of the resonant units 10 located on different supporting substrates 100 are inconsistent, as shown in FIG. Fig.13 The heights of the first device structure 33 and the second device structure 34 are not consistent, and a padding layer 15 may be provided on the substrate 14 to ensure that the resonant units 10 located on different supporting substrates 100 are located in a horizontal plane at the same height after being fixed on the substrate 14, such as in Fig.13 A padding layer 15 is provided below the second device structure 34 having a relatively thin thickness so that the two device structures are located in a horizontal plane at the same height after being fixed on the substrate 14 .

[0117] Based on the different characterization definitions of the above-mentioned resonance units 10, all the resonance units 10 in the pure acoustic hybrid filter structure 1 of this embodiment may be arranged on the same support substrate 100 according to actual needs, such as Figures 3 to 7 The pure acoustic hybrid filter structure 1 is provided with two resonant units 10 and fixed together on the same supporting substrate 100. Figure 8 The pure acoustic hybrid filter structure 1 is provided with three resonance units 10 and fixed together on the same supporting substrate 100. In this case, two methods of preparing at least two different resonance units 10 located on the same supporting substrate 100 by transfer are proposed.

[0118] Method 1:

[0119] S1, such as Fig.14 As shown, a substrate 30 is provided, and the substrate 30 includes a stacked substrate layer 300, a separation layer 301 and a piezoelectric film layer 302 from bottom to top; as an example, Fig.14 The material of the base layer 300 in the base 30 can be the same as the material of the piezoelectric film layer 302. In this case, the separation layer 301 can be formed by ion implantation. Fig.15The material of the base layer 300 in the base 30 is different from the material of the piezoelectric film layer 302. In this case, the material of the separation layer 301 is selected to be compatible with the etching solution, and the etching solution can etch away the separation layer 301 without damaging other material layers;

[0120] S2, such as Fig.16 As shown, the support substrate 100 is fixed on the piezoelectric film layer 302, and the size of the support substrate 100 is larger than the size of the piezoelectric film layer 302; the connection between the two can be achieved by using an existing conventional fixing method, such as bonding;

[0121] S3, such as Fig.17 As shown, the base layer 300 and the piezoelectric film layer 302 are separated based on the separation layer 301; when the separation layer 301 is formed by ion implantation, it is preferred to use an annealing furnace to perform heat treatment to cause the separation layer 301 to break and separate the base layer 300 from the piezoelectric film layer 302; when the separation layer 301 is a material compatible with a corrosive solution, it is preferred to use a solution corrosion method to corrode the separation layer 301 and separate the base layer 300 from the piezoelectric film layer 302; as shown Fig.18 As shown, when the separation layer 301 is cracked by heat treatment in an annealing furnace, part of the separation layer 301 will remain on the piezoelectric film layer 302. At this time, the remaining separation layer 301 needs to be removed to obtain Fig.19 The piezoelectric film layer 302 shown has no residual separation layer 301 on the surface;

[0122] S4, such as Fig. 20 As shown, corresponding interdigital electrodes 102 are formed on the piezoelectric film layer 302 to obtain an intermediate structure 303, and the intermediate structure 303 realizes the preparation of a resonance unit;

[0123] S5, taking steps S1 to S4 as a cycle unit for preparing each resonance unit, and when preparing the next resonance unit, using the intermediate structure obtained after the previous resonance unit is prepared as the supporting substrate in the preparation process of the next resonance unit; for example, Fig.21 As shown, in the preparation process of the second resonance unit, the intermediate structure 303 obtained by preparing the first resonance unit is used as the support substrate in the preparation process of the second resonance unit, and when the support substrate is fixed on the piezoelectric film layer in the preparation of the next resonance unit, the blank area of ​​the support substrate 100 in the intermediate structure obtained by preparing the previous resonance unit is used (the blank area refers to the area on the surface of the support substrate where the piezoelectric film layer is not fixed);

[0124] S6, such as Fig. 22 As shown, step S5 is repeated until a required number of different resonance units 10 are formed on the support substrate 100 .

[0125] Method 2:

[0126] S1, such as Fig.23 As shown, a first substrate 31 is provided, and the first substrate 31 includes a first substrate layer 310, a first separation layer 311 and a first piezoelectric film layer 312 stacked from bottom to top; as an example, the material of the first substrate layer 310 of the first substrate 31 can be the same as the material of the first piezoelectric film layer 312, and the first separation layer 311 can be formed by ion implantation. In addition, the material of the first substrate layer 310 in the first substrate 31 is different from the material of the first piezoelectric film layer 312, and the material of the first separation layer 311 is selected to be compatible with the corrosive solution, and the corrosive solution can corrode the first separation layer 311 without damaging other material layers;

[0127] S2, such as Fig.24 As shown, the support substrate 100 is fixed on the first piezoelectric film layer 312, and the size of the support substrate 100 is larger than the size of the first piezoelectric film layer 312; the connection between the two can be achieved by using an existing conventional fixing method, such as bonding;

[0128] S3, such as Fig.25 As shown, the first base layer 310 and the first piezoelectric film layer 312 are separated based on the first separation layer 311; when the first separation layer 311 is formed by ion implantation, it is preferred to use an annealing furnace to perform heat treatment to cause the first separation layer 311 to break and separate the first base layer 310 from the first piezoelectric film layer 312; when the first separation layer 311 is a material compatible with a corrosive solution, it is preferred to use a solution corrosion method to corrode the first separation layer 311 and separate the first base layer 310 from the first piezoelectric film layer 312; as shown Fig.25 As shown, after the first separation layer 311 is cracked by heat treatment in an annealing furnace, part of the first separation layer 311 will remain on the first piezoelectric film layer 312. At this time, the remaining first separation layer 311 needs to be removed to obtain the following Fig. 27 The first piezoelectric film layer 312 is shown without any residual first separation layer 311 on the surface;

[0129] S4, such as Fig.28 As shown, a corresponding interdigitated electrode 102 is formed on the first piezoelectric film layer 312 to obtain a first intermediate structure 313, and the first intermediate structure 313 realizes the preparation of a resonance unit;

[0130] S5, such as Fig.29 As shown, a second substrate 32 is provided, and the second substrate 32 includes, from bottom to top, a stacked second substrate layer 320, a second separation layer 321, and a second piezoelectric film layer 322; as an example, the material of the second substrate layer 320 of the second substrate 32 can be the same as the material of the second piezoelectric film layer 322, and the second separation layer 321 can be formed by ion implantation. In addition, the material of the second substrate layer 320 in the second substrate 32 is different from the material of the second piezoelectric film layer 322, and the material of the second separation layer 321 is selected to be compatible with the corrosive solution, and the corrosive solution can corrode the second separation layer 321 without damaging other material layers;

[0131] S6, such as Fig.30 and Fig.31 As shown, a corresponding interdigitated electrode 102 is formed on the second piezoelectric film layer 322, and the second base layer 320 is separated from the second piezoelectric film layer 322 based on the second separation layer 321 to obtain a second intermediate structure 314;

[0132] S7, such as Fig.32 As shown, the second intermediate structure 314 is fixed on the first intermediate structure 313;

[0133] S8, such as Fig.33 As shown, steps S5 to S7 are used as a circulation unit in which each different second intermediate structure 314 is prepared and fixed on a blank area of ​​the supporting substrate 100 of the first intermediate structure 313 (the blank area refers to the area on the surface of the supporting substrate where the piezoelectric film layer is not fixed), until the required number of different resonance units 10 are formed on the supporting substrate 100.

[0134] As described above, all the resonance units 10 in the pure acoustic hybrid filter structure 1 may be arranged on two or more different support substrates 100 according to actual needs, and the device structure on the same support substrate 100 may be composed of only one resonance unit 10, or may be composed of two or more different resonance units 10. When it is composed of two or more different resonance units 10, the above method 1 or method 2 may also be used to achieve the preparation of at least two different resonance units 10 located on the same support substrate 100.

[0135] The following is a further explanation and verification of the beneficial effects of the pure acoustic hybrid filter structure in the present application in combination with comparative examples and experimental examples. Obviously, the experimental examples described are only part of the experimental examples of the present invention, not all of the experimental examples. Based on the experimental examples of the present invention, all other experimental examples obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0136] like Fig.34 As shown, it is a schematic diagram of the electrical topology structure of the filter structure of comparative example 1 and comparative example 3; Fig.38 As shown, it is a schematic diagram of the electrical topology of the filter structure of comparative example 2.

[0137] Comparative Example 1:

[0138] For frequency bands exceeding 4 GHz, such as N79 (4400 MHz-5000 MHz), due to the very high resonant frequency and considering the line width requirements, SH-SAW with a sound velocity of about 3800 m / s can no longer be used as a filter to build a resonator. Generally, LL-SAW with a sound velocity of about 6000 m / s is used. It is implemented based on LL-SAW excited by the same specification structure, such as based on the same thickness LiNbO3 piezoelectric film / SiC heterogeneous support substrate and the same thickness of metal interdigital electrodes. On the one hand, due to the high sound velocity of LL-SAW, when the cutoff frequency is close to the SiC heterogeneous support substrate, the admittance curve will show a more significant spurious response at the high frequency end (generally appearing near the antiresonance point); on the other hand, due to the anisotropy of the elastic constants, piezoelectric parameters and other physical parameters of the LiNbO3 piezoelectric film, the sound waves transmitted inside it have significant dispersion in terms of sound velocity, cutoff frequency, electromechanical coupling coefficient and other performances. In addition, when designing, it should be noted that the frequency of the resonator located on the series arm of the resonator is higher, and the corresponding sound wave wavelength is reduced. The ratio of the piezoelectric film thickness of the resonator on the series arm of the resonator to the sound wave wavelength is different from the ratio of the piezoelectric film thickness of the resonator on the parallel arm of the resonator to the sound wave wavelength, resulting in different dispersion characteristics. One of the resonators on the series arm of the resonator and the resonator on the parallel arm of the resonator will always fail to obtain the corresponding optimal ratio of the piezoelectric film thickness to the wavelength. In this comparative example, the four resonators on the resonator series arm and the three resonators on the resonator parallel arm are all arranged on a LiNbO3 piezoelectric film / SiC heterogeneous support substrate with a thickness of 340.4nm, the thickness of the interdigital electrode is set to 88.8nm, the acoustic wavelength of the four resonators on the resonator series arm is 1.32 microns, and the acoustic wavelength of the three resonators on the resonator parallel arm is 1.48 microns. Fig.35 As shown in (a), the admittance response of the resonator on the series arm of the resonator has the problem of clutter pointed out by B, such as Fig.35As shown in (b), the resonator based on this resonant response will cause the formed filter to have significant spurious response at the rear position of the passband, which will cause the out-of-band suppression to deteriorate or cause interference to signals in other frequency bands.

[0139] Experimental Example 1:

[0140] Based on the problems existing in the filter structure of comparative example 1, the design principle of the pure acoustic hybrid filter structure proposed by the present invention is used in this experimental example to optimize the ratio of the thickness of the piezoelectric film to the wavelength of the sound wave of the resonator on the series arm of the resonator and the parallel arm of the resonator. While ensuring that the speed of the sound wave is less than the speed of the slow shear wave of the supporting substrate, that is, the sound wave energy is still well confined inside the piezoelectric film, the ratio of the thickness of the piezoelectric film to the wavelength of the sound wave suitable for the resonator on the series arm of the resonator and the parallel arm of the resonator is designed respectively, and a pure acoustic hybrid filter structure is constructed when there is no noise in the two frequency responses. In addition, according to the preparation method of the pure acoustic hybrid filter structure proposed by the present invention, the resonators on the series arm of the resonator and the parallel arm of the resonator can obtain the best ratio of the thickness of the piezoelectric film to the wavelength of the sound wave and the ratio of the thickness of the metal interdigital electrode to the wavelength of the sound wave by transfer. The specific setting method is as follows: Fig.36 As shown, the four resonators on the series arm of the resonator are arranged on the first resonant unit 104, and the three resonators on the parallel arm of the resonator are arranged on the second resonant unit 105. The two resonant units (i.e., the first resonant unit 104 and the second resonant unit 105) are constructed into the pure acoustic hybrid filter structure by fixed-point transfer; wherein the first resonant unit 104 is a LiNbO3 piezoelectric film / SiC support substrate with a thickness of 315.1nm, the thickness of the interdigital electrode is 82.2nm, and the typical line width (the width of the interdigital electrode) is 343nm; the second resonant unit 105 is a LiNbO3 piezoelectric film / SiC support substrate with a thickness of 340.4nm, the thickness of the interdigital electrode is 88.8nm, and the typical line width (the width of the interdigital electrode) is 370nm. Fig.37 As shown, at this time, the clutter B that appears in the admittance response of the resonator on the resonator series arm of Example 1 disappears, and the clutter in the response of the pure acoustic hybrid filter structure built with the two optimized resonators as the basic resonant units disappears, and the out-of-band suppression level is improved. Therefore, the design method of the pure acoustic hybrid filter structure proposed in the experimental example can make the resonators on the resonator series arm and the resonator parallel arm simultaneously obtain the optimal ratio of piezoelectric film thickness to acoustic wavelength and the ratio of metal interdigital electrode thickness to acoustic wavelength without clutter, thereby obtaining a better filter response.

[0141] Comparative Example 2:

[0142] The target frequency band of this comparative example is B41 (2496MHz~2696MHz), and the filter structure is designed based on LiNbO3 piezoelectric film / SiC heterogeneous support substrate, such as Fig.38 As shown, four resonators are arranged on the series arm of the resonator, including two S1 resonators and two S2 resonators, and three resonators are arranged on the parallel arm of the resonator, including two P1 resonators and one P2 resonator. The resonant frequencies of the S1 resonator, the S2 resonator, the P1 resonator and the P2 resonator are achieved by adjusting the width of the interdigital electrodes. The seven resonators are all arranged on the LiNbO3 piezoelectric film / SiC heterogeneous support substrate. Table 1 shows the basic design parameters of the four types of resonators. At this time, thanks to the large electromechanical coupling coefficient of the LiNbO3 piezoelectric film like Fig.39 As shown in (a), Basically, full coverage of B41 can be achieved at 24%, such as Fig.39 As shown in (b), the filter structure built based on this resonant response has a passband with a left side edge steepness of about 0.88 dB / MHz and a right side edge steepness of about 1.07 dB / MHz. The rectangularity and band edge steepness of the filter structure are poor. The series and parallel resonators of this comparative example are based on a 300 nm thick LiNbO3 piezoelectric film / SiC substrate, the thickness of the forked electrode is 120 nm, the acoustic wavelengths of the S1 resonator and the S2 resonator are 1.81 microns and 1.80 microns, respectively, and the acoustic wavelengths of the P1 resonator and the P2 resonator are 2.11 microns and 2.1 microns, respectively.

[0143] Table 1: Basic design parameters of the resonator

[0144]

[0145] Experimental Example 2:

[0146] Based on the problems existing in the filter structure of comparative example 2, the design principle of the pure acoustic hybrid filter structure proposed by the present invention is used in this experimental example to mix the sound waves excited by the LiNbO3 single crystal piezoelectric film and the sound waves excited by the LiTaO3 single crystal piezoelectric film to build a pure acoustic hybrid filter structure, that is, the resonance unit is excited by the LiNbO3 single crystal piezoelectric film and the LiTaO3 single crystal piezoelectric film respectively to excite the sound waves, and the advantages of the two are combined, and the large-bandwidth LiNbO3 single crystal piezoelectric film is used to broaden the passband of the pure acoustic hybrid filter structure, and the LiTaO3 single crystal piezoelectric film with an ultra-high quality factor is used to design the rectangularity and the steepness of the band edge, and the frequency temperature drift characteristics of the LiTaO3 single crystal with half of the LiNbO3 single crystal are used to reduce the frequency drift of the passband and the band edge when the temperature changes. The specific setting method is: based on the electrical topology of the filter structure that is the same as that of comparative example 2, such as Fig.40As shown, two P1 resonators in the parallel arm of the resonator and two S1 resonators in the series arm of the resonator are arranged in a first resonant unit 104 composed of a LiNbO3 single crystal piezoelectric film / SiC heterogeneous support substrate. The first resonant unit 104 has the characteristics of large bandwidth and large temperature drift. One P2 resonator in the parallel arm of the resonator and two S2 resonators in the series arm of the resonator are arranged in a second resonant unit 105 composed of a LiTaO3 single crystal piezoelectric film / SiC heterogeneous support substrate. The resonant unit 105 has the characteristics of high quality factor and low temperature drift; wherein, the P1 resonator and the S1 resonator are both based on a 300nm thick LiNbO3 piezoelectric film / SiC substrate, the thickness of the interdigital electrode is 120nm, and the wavelengths of the acoustic waves are 1.81 microns and 2.11 microns respectively; the P2 resonator and the S2 resonator are based on a 500nm thick LiTaO3 piezoelectric film / SiC substrate, the thickness of the interdigital electrode is 100nm, and the wavelengths of the acoustic waves are 1.56 microns and 1.69 microns respectively. At this time, Table 2 redesigns the basic design parameters of the four types of resonators, and the second resonant unit located in the LiTaO3 heterostructure It has been reduced to half of the original level, which is in line with the level of LiTaO3 single crystal piezoelectric film. Fig.41 (a) and (b) show the passband responses of the four types of resonators and the pure acoustic hybrid filter structure built based on them, respectively. At this time, although the second resonant unit located in the LiTaO3 heterostructure are significantly reduced, but thanks to the first resonance unit 104 is still in On the larger LiNbO3 piezoelectric film structure, the pure acoustic hybrid filter structure can still achieve full coverage of B41. At this time, the steepness of the left side of the passband is about 1.81dB / MHz, and the steepness of the right side of the passband is about 2.14dB / MHz. That is, while ensuring full coverage of B41, the rectangularity and band edge steepness of the filter are improved, and the frequency point of the band edge corresponds to a resonance unit with a smaller temperature drift, which can also ensure higher passband response stability under variable temperature conditions.

[0147] Table 2: Basic design parameters of the resonator

[0148]

[0149] Comparative Example 3:

[0150] For frequency bands above 3.5 GHz, such as N78 and N77, the electrical topology of the filter structure is as follows Fig.34As shown, the filter structure is constructed using a pure SH-SAW resonator, that is, it is realized by exciting SH-SAW based on the same specification structure, wherein the resonant frequency of the four resonators on the resonator series arm and the three resonators on the resonator parallel arm is realized by adjusting the width of the interdigital electrode, and the seven resonators are all arranged on the same piezoelectric film and the same heterogeneous support substrate. Table 3 shows the basic design parameters of the four resonators S1 on the resonator series arm and the three resonators P1 on the resonator parallel arm. The SH-SAW resonator of this comparative example is based on a LiNbO3 piezoelectric film / SiC substrate with a thickness of 280nm, the thickness of the interdigital electrode is 98nm, and the acoustic wavelengths are 1.40 microns and 1.12 microns respectively. Fig.42 (a) is the admittance response of the four resonators S1 on the resonator series arm and the three resonators on the resonator parallel arm. Fig.42 (b) is the passband response of the pure acoustic hybrid filter structure built on it. At this time, the resonance frequency of the resonator on the series arm of the resonator reaches 3.6 GHz. For SH-SAW with a sound speed of about 3800 m / s, the resonance frequency of the resonator on the series arm of the resonator reaches 3.6 GHz, which means that the device line width (i.e., the width of the forked electrode) will reach 265 nm (the wavelength of the sound wave is about 1.06 microns), which greatly increases the device line width requirements and preparation difficulty. In addition, the resistance of the thin forked electrode is large, and the electrode loss is increased, which has a great impact on the room temperature performance stability and power tolerance performance.

[0151] Table 3: Basic design parameters of the resonator

[0152]

[0153] Experimental Example 3:

[0154] Based on the problems existing in the filter structure of comparative example 3, the design principle of the pure acoustic hybrid filter structure proposed in the present invention is used in this experimental example, and the electrical topology structure of the filter structure is the same as that of comparative example 3, such as Fig.43As shown, the horizontal shear wave SH-SAW and the longitudinal leakage wave LL-SAW excited by the LiNbO3 single crystal piezoelectric film are mixed to build a pure acoustic hybrid filter structure, the high-frequency resonator on the series arm of the resonator is realized by the high-sound-velocity LL-SAW, and the low-frequency resonator on the parallel arm of the resonator is realized by the SH-SAW, which can be based on the same material of LiNbO3 piezoelectric film / SiC heterogeneous support substrate, that is, the four high-frequency resonators on the series arm of the resonator are prepared on the first resonance unit 104, and the three low-frequency resonators on the parallel arm of the resonator are prepared on the second resonance unit 105, and the first resonance unit 104 and the second resonance unit 105 both use the same material of LiNbO3 piezoelectric film / SiC heterogeneous support substrate, the difference is that the arrangement direction of the forked electrode fingers of the four high-frequency resonators on the series arm of the resonator is different from the arrangement direction of the forked electrode fingers of the three low-frequency resonators on the parallel arm of the resonator (that is, there is an angle). Excited by LL-SAW with a sound velocity of about 6000m / s, the device line width of the resonator on the series arm of the resonator is still greater than 416nm (the wavelength of the sound wave is about 1.67 microns) when the resonant frequency reaches 3.6GHz, which effectively relaxes the device line width limit of the resonator on the series arm of the resonator, helps the device stability and heat dissipation during high-frequency vibration, and also has advantages in power tolerance. Fig.44 (a) and 44(b) respectively show the passband responses of the two types of resonators of this experimental example and the pure acoustic hybrid filter structure built based on them. In addition, the arrangement direction of the interdigital electrode fingers of the four high-frequency resonators on the series arm of the resonator can be adjusted so that the arrangement direction of the interdigital electrode fingers of the four high-frequency resonators on the series arm of the resonator and the arrangement direction of the interdigital electrode fingers of the three low-frequency resonators on the parallel arm of the resonator have different angles, for example Fig.45 (a) and (b) show three different angle settings, and three different The frequency response of the three low-frequency resonators on the parallel arm of the determined resonator is designed to realize three filter responses with different bandwidths, which is conducive to the flexible design of the passband width of the filter. The SH-SAW resonator in this experimental example is based on a 280nm thick LiNbO3 piezoelectric film / SiC substrate, the thickness of the forked electrode is 98nm, the wavelength of the acoustic wave is 1.4 microns, and the arrangement direction of the forked electrode in the plane is 9° clockwise with the in-plane Y axis; the LL-SAW resonator is based on a 423nm thick LiNbO3 piezoelectric film / SiC substrate, the thickness of the forked electrode is 110.4nm, the wavelength of the acoustic wave is 1.84 microns, and the arrangement direction of the forked electrode in the plane is 50° clockwise with the in-plane Z axis. In addition, the resonant frequency and Realize flexible adjustment of hybrid filter bandwidth.

[0155] Therefore, by using high-speed acoustic waves LL-SAW for the high-frequency resonator on the series arm of the resonator, the line width problem of the high-frequency resonator can be solved, thereby relaxing the performance and constraints. However, due to the high sound velocity of LL-SAW, the cutoff frequency may be located near the anti-resonance point, which will lead to larger losses in the future. It is best that the passband does not fall at this position. Therefore, the resonator on the parallel arm of the resonator can continue to use SH-SAW. Therefore, SH-SAW and LL-SAW are mixed to prepare a hybrid filter.

[0156] In summary, the present invention provides a pure acoustic hybrid filter structure and a preparation method thereof. According to actual needs, the resonator is set on different resonance units, that is, the resonator set on the same resonance unit is the same, and the resonator set on different resonance units is different. This method can fully integrate the advantages of different resonance units, and realize the independent design of the parameters of the resonator series arm and the resonator parallel arm in the electrical topology structure of the pure acoustic hybrid filter structure, so as to achieve the effective regulation of the resonant frequency of the target resonance, the typical line width of the device, the piezoelectric transduction level and the out-of-band clutter, etc., effectively reduce the difficulty of device preparation, suppress or weaken the excitation of the spurious mode, improve the design flexibility of the acoustic filter, and realize the integration of the device level; in addition, the adjustable bandwidth can be achieved without the addition of external electrical components, so as to obtain a flat, low insertion loss filter passband response, improve the transmission efficiency of the communication signal in the passband, and is not constrained by the line width, and meet various application requirements. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0157] 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 pure acoustic hybrid filter structure, characterized in that: The pure acoustic hybrid filter structure includes: a plurality of resonators, and a plurality of the resonators are combined to form an electrical topological structure, and the electrical topological structure includes a resonator series arm and a resonator parallel arm; The pure acoustic hybrid filter structure includes at least two different resonance units in terms of physical structure, and all the resonators are respectively arranged on all the different resonance units according to preset requirements; The resonance unit includes a support substrate, a piezoelectric film and interdigital electrodes in sequence along the thickness direction, wherein the interdigital electrodes on all different resonance units are electrically connected through block electrodes to realize electrical connection of all resonators in the electrical topology structure, and the sound velocity of the support substrate is not less than the sound velocity of the highest sound velocity mode in the target sound wave mode; Elements characterizing the differences of the resonance units include: the support substrates are different and / or the piezoelectric films are different and / or the interdigitated electrodes are different. Here, the width of the electrode fingers in the interdigitated electrodes is not used as an element characterizing the differences of the resonance units.

2. The pure acoustic hybrid filter structure according to claim 1, characterized in that: The different supporting substrates include different types of materials of the supporting substrates and / or different material cuts of the supporting substrates and / or different thicknesses of the supporting substrates; the different piezoelectric films include different types of materials of the piezoelectric films and / or different thicknesses of the piezoelectric films and / or different material cuts of the piezoelectric films; the different interdigitated electrodes include different types of materials of the interdigitated electrodes and / or different thicknesses of the interdigitated electrodes and / or different arrangement directions of the electrode fingers in the interdigitated electrodes.

3. The pure acoustic hybrid filter structure according to claim 1, characterized in that: At least one of the resonance units also includes a dielectric layer, which is arranged between the supporting substrate and the piezoelectric film or between the piezoelectric film and the interdigitated electrodes; or the supporting substrate of at least one of the resonance units is provided with a blind groove, and a corresponding part of the thickness of the piezoelectric film is embedded in the blind groove.

4. The purely acoustic hybrid filter structure according to claim 3, characterized in that: The material of the dielectric layer is one of silicon oxide, carbon-doped silicon oxide, silicon nitride and aluminum nitride.

5. The purely acoustic hybrid filter structure according to claim 1, characterized in that: The material of the piezoelectric film is one of lithium niobate, lithium tantalate, quartz, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, lead magnesium niobate titanate, gallium nitride, gallium oxide, and gallium arsenide; the material of the supporting substrate is one of silicon carbide, silicon, sapphire, quartz, diamond, diamond-like carbon, gallium nitride, boron carbide, boron nitride, and aluminum nitride.

6. The purely acoustic hybrid filter structure according to claim 1, characterized in that: All the different resonance units are located in a horizontal plane at the same height or the surface height difference of all the different resonance units is within a hundred nanometer level.

7. The purely acoustic hybrid filter structure according to claim 1, characterized in that: All the different resonance units are arranged on the same supporting substrate; or all the different resonance units are arranged on two or more different supporting substrates, and all the different resonance units are connected together on a substrate.

8. The purely acoustic hybrid filter structure according to claim 7, characterized in that: When all the different resonance units are arranged on two or more different support substrates, and all the different resonance units are connected together on one substrate, a raising layer is arranged on the substrate to ensure that all the different resonance units are located in a horizontal plane at the same height.

9. A method for preparing a pure acoustic hybrid filter structure, characterized in that: The preparation method comprises: At least two different resonance units are prepared by a transfer method; wherein, the multiple resonators included in the pure acoustic hybrid filter structure are respectively prepared on all different resonance units according to preset needs, each of the resonance units includes a supporting substrate, a piezoelectric film and a forked electrode in sequence along the thickness direction, and the sound velocity of the supporting substrate is not less than the sound velocity of the highest sound velocity mode in the target sound wave mode, and the elements characterizing the differences of the resonance units include: the supporting substrates are different and / or the piezoelectric films are different and / or the forked electrodes are different, and the width of the electrode fingers in the forked electrodes is not used as an element characterizing the differences of the resonance units; Block electrodes are formed on the interdigital electrodes of all the different resonance units to electrically connect the interdigital electrodes of all the resonators to form an electrical topology structure, wherein the electrical topology structure includes a resonator series arm and a resonator parallel arm.

10. The method for preparing a pure acoustic hybrid filter structure according to claim 9, characterized in that: All the different resonance units are prepared on two or more different support substrates, and the steps of preparing at least two different resonance units by transfer printing include: preparing the resonance units located on different support substrates respectively; A substrate is provided, and the resonance units located on different support substrates are arranged in contact with each other in sequence through all the support substrates and fixed on the substrate.

11. The method for preparing a pure acoustic hybrid filter structure according to claim 10, characterized in that: When the heights of the resonance units on different supporting substrates are inconsistent, a raising layer is provided on the substrate to ensure that the resonance units on different supporting substrates are located in a horizontal plane at the same height after being fixed on the substrate.

12. The purely acoustic hybrid filter structure according to any one of claims 9 to 11, characterized in that: At least two different resonant units are prepared on the same support substrate, and the steps of preparing at least two different resonant units located on the same support substrate by a transfer method include: S1. providing a substrate, wherein the substrate comprises, from bottom to top, a stacked substrate layer, a separation layer and a piezoelectric film layer; S2, fixing the supporting substrate on the piezoelectric film layer, wherein the size of the supporting substrate is larger than the size of the piezoelectric film layer; S3, separating the base layer from the piezoelectric film layer based on the separation layer; S4, forming corresponding interdigital electrodes on the piezoelectric film layer to obtain an intermediate structure, which realizes the preparation of a resonance unit; S5, taking steps S1 to S4 as a cycle unit for preparing each resonance unit, and when preparing the next resonance unit, using the intermediate structure obtained by preparing the previous resonance unit as the supporting substrate in the preparation process of the next resonance unit, and when fixing the supporting substrate on the piezoelectric film layer in preparing the next resonance unit, using the blank area of ​​the supporting substrate in the intermediate structure obtained by preparing the previous resonance unit; S6. Repeat step S5 until a required number of different resonance units are formed on the supporting substrate.

13. The purely acoustic hybrid filter structure according to any one of claims 9 to 11, characterized in that: At least two different resonant units are prepared on the same support substrate, and the steps of preparing at least two different resonant units located on the same support substrate by a transfer method include: S1, providing a first substrate, wherein the first substrate comprises, from bottom to top, a first substrate layer, a first separation layer, and a first piezoelectric film layer stacked one on top of the other; S2, fixing the supporting substrate on the first piezoelectric film layer, wherein the size of the supporting substrate is larger than the size of the first piezoelectric film layer; S3, separating the first substrate layer from the first piezoelectric film layer based on the first separation layer; S4, forming corresponding interdigital electrodes on the first piezoelectric film layer to obtain a first intermediate structure, wherein the first intermediate structure realizes the preparation of a resonance unit; S5, providing a second substrate, wherein the second substrate comprises, from bottom to top, a stacked second substrate layer, a second separation layer, and a second piezoelectric film layer; S6, forming corresponding interdigital electrodes on the second piezoelectric film layer, and separating the second substrate layer from the second piezoelectric film layer based on the second separation layer to obtain a second intermediate structure; S7, fixing the second intermediate structure on the first intermediate structure; S8. Take steps S5 to S7 as a circulation unit for preparing each different second intermediate structure and fixing it on the blank area of ​​the supporting substrate of the first intermediate structure, until a required number of different resonance units are formed on the supporting substrate.

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