TF-SAW resonator and preparation method thereof, and filter

Abstract

The invention provides a TF-SAW resonator, a preparation method thereof and a filter, and relates to the technical field of semiconductors. The interdigital electrode comprises piston structures, sub-bus bars, metal bumps and recesses, the piston structures are positioned at two ends of the acoustic part, it can be understood that the piston structures are arranged at the tail end areas of the acoustic part on the electrode finger bars, and larger sound velocity difference is realized by changing the sound velocity of the tail end areas; therefore, the transverse mode is reflected in different directions to avoid energy dissipation caused by resonance; according to the TF-SAW resonator, the sub bus bars, the metal bumps and the recesses are arranged on a propagation path of a transverse mode, clutter interference is eliminated by causing sound velocity difference, so that clutter mode interference is inhibited to the greatest extent, the Q value is improved, the insertion loss flatness in a passband is improved, the performance of standing waves in the passband is improved, the insertion loss is improved and the like, and the performance of the TF-SAW resonator is further improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and particularly to a TF-SAW resonator, a preparation method thereof, and a filter. Background Art

[0002] With the rapid development of 5G communication technology, the market demand for RF resonators in the 5G frequency band has increased sharply. As one of the effective solutions to achieve high-performance RF filter components, the TF-SAW (Thin-Film Surface Acoustic Wave) resonator has the advantages of high performance, low cost, and small device size, and has been widely used in various communication devices.

[0003] Then, how to improve the performance of the TF-SAW resonator to meet the high-performance requirements of various communication devices is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0004] In view of the above problems, the present application provides a TF-SAW resonator, a preparation method thereof, and a filter, so as to achieve the purpose of improving the performance of the TF-SAW resonator. The specific solutions are as follows:

[0005] In a first aspect of the present application, a TF-SAW resonator is provided, and the TF-SAW resonator includes:

[0006] A substrate;

[0007] A piezoelectric thin film layer located on one side of the substrate;

[0008] Interdigital electrodes located on the side of the piezoelectric thin film layer away from the substrate; the interdigital electrodes include bus bars, sub-bus bars, and electrode finger bars. The electrode finger bars include an acoustic part and an electrical part, and the two ends of the electrical part are respectively connected to the acoustic part and the bus bar; the bus bar includes a first bus bar and a second bus bar arranged oppositely in a first direction, and the sub-bus bar includes a first sub-bus bar and a second sub-bus bar arranged oppositely in the first direction; the electrode finger bars include a first electrode finger bar located on the first bus bar and a second electrode finger bar located on the second bus bar; the first sub-bus bar is located between the first bus bar and the second electrode finger bar and is connected to the electrical part of the first electrode finger bar; the second sub-bus bar is located between the second bus bar and the first electrode finger bar and is connected to the electrical part of the second electrode finger bar; the bus bar and the sub-bus bar extend in a second direction, the length extension direction of the electrode finger bar is parallel to the first direction, the first direction and the second direction are parallel to the plane where the substrate is located, and the first direction and the second direction intersect;

[0009] Piston structures located at both ends of the acoustic part;

[0010] Metal bumps and depressions; the bus bar includes a first surface facing the sub-bus bar side, and the sub-bus bar includes a second surface facing the bus bar side; one of the first surface and the second surface is provided with the metal bumps, and the other surface is provided with the depressions; the metal bumps and the depressions are arranged in one-to-one correspondence in the first direction.

[0011] Preferably, in the above TF-SAW resonator, the first surface is provided with the depressions, and the second surface is provided with the metal bumps;

[0012] In the first direction, the depressions on the first bus bar, the metal bumps on the first sub-bus bar, and the piston structures on the second electrode finger bars are arranged in correspondence;

[0013] In the first direction, the depressions on the second bus bar, the metal bumps on the second sub-bus bar, and the piston structures on the first electrode finger bars are arranged in correspondence.

[0014] Preferably, in the above TF-SAW resonator, the length of the depression in the second direction is equal to the length of the metal bump in the second direction and is L1, and the width of the piston structure in the second direction is L2;

[0015] Wherein, L1 = L2.

[0016] Preferably, in the above TF-SAW resonator, the width of the depression in the first direction is equal to the width of the metal bump in the first direction and is L3;

[0017] Wherein, 0.2×λ ≤ L3 ≤ 0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0018] Preferably, in the above TF-SAW resonator, the width of the piston structure in the second direction is L2;

[0019] Wherein, 0.5×λ ≤ L2 ≤ 0.6×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0020] Preferably, in the above TF-SAW resonator, the piston structure includes a first piston structure and a second piston structure;

[0021] The second piston structure on the first electrode finger bar extends to the area where the first sub-bus bar is located and is connected to the first sub-bus bar;

[0022] The second piston structure on the second electrode finger extends to the area where the second sub-bus bar is located and is connected to the second sub-bus bar.

[0023] Preferably, in the above TF-SAW resonator, the length of the first piston structure in the first direction is L4;

[0024] wherein, 0.4×λ ≤ L4 ≤ 0.6×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0025] Preferably, in the above TF-SAW resonator, in the first direction, the distance between the first piston structure and the second piston structure is L5;

[0026] wherein, 15×λ ≤ L5 ≤ 40×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0027] Preferably, in the above TF-SAW resonator, the maximum width of the bus bar in the first direction is L6;

[0028] wherein, 3×λ ≤ L6 ≤ 4×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0029] Preferably, in the above TF-SAW resonator, the width of the sub-bus bar in the first direction is L7;

[0030] wherein, 0.2×λ ≤ L7 ≤ 0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0031] Preferably, in the above TF-SAW resonator, the width of the electrode finger in the second direction is L8;

[0032] wherein, 0.2×λ ≤ L8 ≤ 0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0033] Preferably, in the above TF-SAW resonator, in the first direction, the distance between the electrode finger and the sub-bus bar is L9;

[0034] wherein, 0.3μm ≤ L9 ≤ 0.7μm.

[0035] Preferably, in the above TF-SAW resonator, in the first direction, the minimum distance between the bus bar and the sub-bus bar is L10;

[0036] wherein, 1.5×λ ≤ L10 ≤ 2.2×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0037] Preferably, in the above TF-SAW resonator, the TF-SAW resonator further includes:

[0038] A reflection grating located at at least one end of the interdigital electrode along the second direction.

[0039] Preferably, in the above TF-SAW resonator, the width of the electrode finger bars in the reflection grating in the second direction is L11;

[0040] wherein, 0.2×λ≤L11≤0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0041] Preferably, in the above TF-SAW resonator, the TF-SAW resonator further includes:

[0042] At least one dielectric layer located between the substrate and the piezoelectric thin film layer.

[0043] Preferably, in the above TF-SAW resonator, the at least one dielectric layer includes a temperature compensation layer.

[0044] The second aspect of the present application provides a method for manufacturing a TF-SAW resonator, and the method for manufacturing the TF-SAW resonator includes:

[0045] Provide a substrate;

[0046] Form a piezoelectric thin film layer on one side of the substrate;

[0047] Form interdigital electrodes on the side of the piezoelectric thin film layer facing away from the substrate; the interdigital electrodes include bus bars, sub-bus bars, and electrode finger bars, the electrode finger bars include acoustic parts and electrical parts, and the two ends of the electrical parts are respectively connected to the acoustic parts and the bus bars; the bus bars include a first bus bar and a second bus bar oppositely arranged in a first direction, and the sub-bus bars include a first sub-bus bar and a second sub-bus bar oppositely arranged in the first direction; the electrode finger bars include a first electrode finger bar located on the first bus bar and a second electrode finger bar located on the second bus bar; the first sub-bus bar is located between the first bus bar and the second electrode finger bar and is connected to the electrical part of the first electrode finger bar; the second sub-bus bar is located between the second bus bar and the first electrode finger bar and is connected to the electrical part of the second electrode finger bar; the bus bars and the sub-bus bars extend in a second direction, the length extension direction of the electrode finger bars is parallel to the first direction, the first direction and the second direction are parallel to the plane where the substrate is located, and the first direction and the second direction intersect; piston structures at both ends of the acoustic part; metal bumps and depressions; the bus bars include a first surface facing the sub-bus bars, and the sub-bus bars include a second surface facing the bus bars; one of the first surface and the second surface is provided with the metal bumps, and the other surface is provided with the depressions; the metal bumps and the depressions are arranged in one-to-one correspondence in the first direction.

[0048] The third aspect of the present application provides a filter, and the filter includes any one of the above TF-SAW resonators.

[0049] With the above technical solutions, the present application provides a TF-SAW resonator, its preparation method, and a filter. The interdigital electrodes include piston structures, sub-bus bars, metal bumps, and depressions. The piston structures are located at both ends of the acoustic part. It can be understood that piston structures are provided in the end regions of the acoustic parts on the electrode finger bars. By changing the sound velocity in these end regions, a larger sound velocity difference can be achieved, so that the transverse modes are reflected in different directions to avoid the formation of resonance and energy dissipation; on the propagation path of the transverse modes, sub-bus bars, metal bumps, and depressions are further provided to eliminate clutter interference by creating a sound velocity difference, so as to suppress spurious mode interference to the greatest extent, improve the Q value, improve the insertion loss flatness in the passband, improve the standing wave performance in the passband, improve the insertion loss, etc., and thus improve the performance of the TF-SAW resonator.

[0050] In the technical solution of the present application, one of the first surface and the second surface is provided with the metal bumps, and the other surface is provided with the depressions; the metal bumps and the depressions are arranged in one-to-one correspondence in the first direction, so as to adjust the energy reflection effect of the regions where the metal bumps are located and the regions where the depressions are located to the greatest extent, thereby improving the performance of the TF-SAW resonator to the greatest extent. Description of the Drawings

[0051] In combination with the accompanying drawings and with reference to the following specific embodiments, the above and other features, advantages and aspects of the various embodiments of the present disclosure will become more apparent. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic and the original elements and elements are not necessarily drawn to scale.

[0052] Figure 1 One of the structural schematic diagrams of a TF-SAW resonator provided by an embodiment of the present invention;

[0053] Figure 2 A schematic diagram of the clutter removal effect of different TF-SAW resonators in an embodiment and a comparative example provided by an embodiment of the present invention;

[0054] Figure 3 Another structural schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0055] Figure 4 A cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0056] Figure 5 A flowchart of a preparation method of a TF-SAW resonator provided by an embodiment of the present invention;

[0057] Figure 6 One of the partial cross-sectional schematic diagrams of a TF-SAW resonator provided by an embodiment of the present invention;

[0058] Figure 7 Another partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0059] Figure 8 Another partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0060] Figure 9 Another partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0061] Figure 10 Another partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0062] Figure 11 This is the sixth partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention. Detailed implementation manners

[0063] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. The terms used in the implementation manners part of the present application are only used to explain the specific embodiments of the present application, rather than being intended to limit the present application. Those of ordinary skill in the art will know that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0064] Surface acoustic wave resonators and filters are acoustic devices widely used in the radio frequency field, integrating low insertion loss and good suppression performance, and having a relatively small volume. They are used to filter out the interference of off-frequency signals, attenuate some frequency components, and only allow the specified frequency components, which is the technical basis for the application of the wireless spectrum as a non-renewable scarce resource. The specific principle can be simply understood as based on the piezoelectric characteristics of piezoelectric materials, using input and output transducer devices such as interdigital transducers to convert electrical signals into mechanical energy, and then converting them back into electrical signals after processing, so as to amplify the required signals, filter out miscellaneous signals and improve the signal quality, and are widely used in various wireless communication devices.

[0065] Currently, filters are mainly divided into SAW filters and BAW (Bulk Acoustic Wave) filters. Among them, surface acoustic wave is an elastic wave that is generated and propagated on the surface of a piezoelectric substrate with piezoelectric characteristics, and the amplitude rapidly decreases as the depth of penetration into the piezoelectric substrate increases. For SAW filters, their manufacturing cost is lower compared with BAW filters, and they are mainly applied to the low-frequency band, with low insertion loss, good suppression, and high temperature sensitivity.

[0066] At the same time, it should be noted that SAW filters also have corresponding limitations. One of them is that they are susceptible to temperature changes. When the temperature rises, the stiffness of the substrate material tends to become smaller and the sound velocity will also decrease. In other words, SAW filters have the defect of temperature drift, that is, the frequency will drift with the operating temperature. Therefore, on the basis of traditional SAW filters, TC-SAW (Temperature Compensated SAW) filters, that is, temperature-compensated SAW filters, are correspondingly produced. It mainly uses the opposite temperature elastic characteristics of the temperature compensation layer (such as the SiO2 layer) and the piezoelectric thin film layer to achieve the compensation of the temperature drift characteristics.

[0067] Furthermore, there are also product designs such as TF-SAW filters for SAW filters. The design of filters often uses resonators as basic units, which can form corresponding topologies and amplify signals of specified frequency components.

[0068] For a TC-SAW resonator, a common SAW resonator, or a TF-SAW resonator, due to the acoustic wave propagating transversely in the surface acoustic wave resonator, a transverse resonance mode will occur in the surface acoustic wave resonator, that is, clutter appears within and near the passband. This clutter will increase the loss of the surface acoustic wave resonator, cause a large fluctuation in the Q value, and reduce the performance of the surface acoustic wave resonator.

[0069] It should be noted that in the embodiments of the present invention, the TF-SAW resonator is mainly described. The embodiments of the present invention provide a TF-SAW resonator, a preparation method thereof, and a filter. By combining a piston structure, a sub-bus bar, and the provided metal bumps and depressions, the suppression effect on transverse mode spurs is enhanced, and the purpose of suppressing spurious mode interference to a greater extent, improving the Q value, improving the insertion loss flatness within the passband, improving the standing wave performance within the passband, improving the insertion loss, and improving the performance of the TF-SAW resonator is achieved.

[0070] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] It should be noted that the orientation terms in the present invention are based on the relative position relationship shown in the drawings and should not be used as an absolute limitation to this application.

[0072] Reference Figure 1 , Figure 1 is one of the schematic structural diagrams of a TF-SAW resonator provided by an embodiment of the present invention. The TF-SAW resonator provided by the embodiment of the present invention includes: a substrate 11.

[0073] A piezoelectric thin film layer 12 located on one side of the substrate 11.

[0074] The interdigital electrode 13 located on the side of the piezoelectric thin film layer 12 facing away from the substrate 11; the interdigital electrode 13 includes a bus bar 14, a sub-bus bar 15 and electrode finger bars 16, the electrode finger bars 16 include an acoustic part A1 and an electrical part A2, and both ends of the electrical part A2 are respectively connected to the acoustic part A1 and the bus bar 14; the bus bar 14 includes a first bus bar 141 and a second bus bar 142 oppositely arranged in the first direction X, and the sub-bus bar 15 includes a first sub-bus bar 151 and a second sub-bus bar 152 oppositely arranged in the first direction X; the electrode finger bars 16 include a first electrode finger bar 161 located on the first bus bar 141 and a second electrode finger bar 162 located on the second bus bar 142; the first sub-bus bar 151 is located between the first bus bar 141 and the second electrode finger bar 162 and is connected to the electrical part A2 of the first electrode finger bar 161; the second sub-bus bar 152 is located between the second bus bar 142 and the first electrode finger bar 161 and is connected to the electrical part A2 of the second electrode finger bar 162; the bus bar 14 and the sub-bus bar 15 extend along the second direction Y, the length extension direction of the electrode finger bars 16 is parallel to the first direction X, the first direction X and the second direction Y are parallel to the plane where the substrate 11 is located, and the first direction X and the second direction Y intersect. It should be noted that in the embodiments of the present invention, the case where the first direction X and the second direction Y are perpendicular is taken as an example for illustration.

[0075] Piston structures 17 located at both ends of the acoustic part A1.

[0076] Metal bumps 10 and depressions 18; the bus bar 14 includes a first surface facing the sub-bus bar 15, and the sub-bus bar 15 includes a second surface facing the bus bar 14; one of the first surface and the second surface is provided with the metal bumps 10, and the other surface is provided with the depressions 18; the metal bumps 10 and the depressions 18 are arranged in one-to-one correspondence in the first direction X.

[0077] Specifically, in the embodiments of the present invention, the substrate 11 serves as a support structure, and the material thereof can be selected from lithium tantalate materials, lithium niobate materials, aluminum nitride materials, sapphire materials, spinel materials, single crystal silicon materials, silicon carbide materials, quartz materials, etc. The piezoelectric thin film layer 12 is made of a piezoelectric material, and the material thereof can be selected from lithium tantalate LT materials or lithium niobate LN materials. The interdigital electrode is usually made of a metal material, and the material thereof can be selected from materials with relatively low resistivity such as Cu materials, Al materials, Au materials, Ti materials, Cr materials, Pt materials, etc.

[0078] The length extension direction of the electrode finger 16 is parallel to the first direction X. A plurality of first electrode fingers 161 on the first bus bar 141 are arranged at intervals in the second direction Y. A plurality of second electrode fingers 162 on the second bus bar 142 are arranged at intervals in the second direction Y. And a plurality of first electrode fingers 161 on the first bus bar 141 and a plurality of second electrode fingers 162 on the second bus bar 142 are arranged crosswise in sequence in the second direction Y. And there is a gap between a plurality of first electrode fingers 161 on the first bus bar 141 and the second bus bar 142, and there is a gap between a plurality of second electrode fingers 162 on the second bus bar 142 and the first bus bar 141. At this time, the bus bar 14 and the electrode finger 16 are distributed in a way similar to the finger crossing, forming the so-called interdigital electrode 13. When the first bus bar 141 and the first electrode fingers 161 thereon are used as the transmitting end, the second bus bar 142 and the second electrode fingers 162 thereon are used as the receiving end. On the contrary, when the first bus bar 141 and the first electrode fingers 161 thereon are used as the receiving end, the second bus bar 142 and the second electrode fingers 162 thereon are used as the transmitting end. The transmitting end part is used to convert an electrical signal into a sound wave, and the sound wave mainly propagates on the surface of the piezoelectric thin film layer 12. The receiving end part is used to convert the received sound wave into an electrical signal for output, so as to realize filtering.

[0079] As Figure 1 shown, in the embodiment of the present application, the recess 18 is arranged on the first surface, and the metal bump 10 is arranged on the second surface as an example for illustration.

[0080] As Figure 1 shown, the sound velocity in the gap region between the electrode finger 16 and the sub-bus bar 15, and the gap region between the metal bump 10 and the bus bar 14 is W1; the sound velocity in the region where the metal bump 10 is located is W2; the sound velocity in the region where the sub-bus bar 15 is located and the region of the part of the bus bar 14 where the recess 18 is not provided is W3; the sound velocity in the region where the electrode finger 16 is located between the piston structures 17 is W4; the sound velocity in the region of the part of the bus bar 14 where the recess 18 is provided is W5; the sound velocity in the region where the piston structure 17 is located is W6; there is a relationship of W1 > W2 > W3 > W4 > W5 > W6.

[0081] In the embodiment of the present invention, the structure of the interdigital electrode 13 further includes a piston structure 17, a sub-bus bar 15, a metal bump 10, and a recess 18. The piston structure 17 is located at both ends of the acoustic part A1. It can be understood that the piston structure 17 is arranged at the end region of the acoustic part A1 on the electrode finger 16, and a larger sound velocity difference is realized by changing the sound velocity in the end region, so that the transverse mode is reflected in different directions to avoid the formation of resonance and energy dissipation.

[0082] In the sub-bus bar 15, the first sub-bus bar 151 is located between the first bus bar 141 and the second electrode finger bar 162, and is connected to the electrical part A2 of the first electrode finger bar 161; the second sub-bus bar 152 is located between the second bus bar 142 and the first electrode finger bar 161, and is connected to the electrical part A2 of the second electrode finger bar 162.

[0083] As Figure 1 shown, the metal bumps 10 are provided on the surface of the sub-bus bar 15 facing the bus bar 14, and the depressions 18 are provided on the surface of the bus bar 14 facing the sub-bus bar 15. At this time, a toothed structure is formed on the surface of the bus bar 14 facing the sub-bus bar 15.

[0084] In the first direction X, the depression 18 on the first bus bar 141, the metal bump 10 on the first sub-bus bar 151, and the piston structure 17 on the second electrode finger bar 162 are correspondingly arranged; in the first direction X, the depression 18 on the second bus bar 142, the metal bump 10 on the second sub-bus bar 152, and the piston structure 17 on the first electrode finger bar 161 are correspondingly arranged.

[0085] It can be understood that on the propagation path of the transverse mode, the sub-bus bar 15, the metal bump 10, and the depression 18 are further provided to change the sound velocity in their respective regions. By creating a sound velocity difference, clutter interference is eliminated. The sub-bus bar 15 can bounce back the energy leaking from the acoustic region, the metal bump 10 can further bounce back the energy leaking from the acoustic region, and the design of the depression 18 can reduce the energy bouncing effect in the region where the depression 18 is located, avoiding too much energy being bounced back into the acoustic region, so as to suppress the spurious mode interference to the greatest extent, improve the Q value, improve the insertion loss flatness in the passband, improve the standing wave performance in the passband, improve the insertion loss, etc., thereby improving the performance of the TF-SAW resonator.

[0086] In the technical solution of the present application, the metal bump 10 is provided on one of the first surface and the second surface, and the depression 18 is provided on the other surface; the metal bump 10 and the depression 18 are arranged in one-to-one correspondence in the first direction X, so as to adjust the energy bouncing effect in the region where the metal bump 10 is located and the region where the depression 18 is located to the greatest extent, thereby improving the performance of the TF-SAW resonator to the greatest extent.

[0087] Next, the technical effects achievable by the technical solution of the present application will be further elaborated and explained by way of comparison.

[0088] Comparative example: The interdigital electrodes in the TF-SAW resonator only include bus bars, electrode finger bars, and dummy electrode finger bars.

[0089] Example:Figure 1 The TF-SAW resonator shown

[0090] Reference Figure 2 , Figure 2 FIG. is a schematic diagram of the clutter removal effect of different TF-SAW resonators in an embodiment and a comparative example provided by the embodiment of the present invention. Among them, the dotted line represents the curve corresponding to the TF-SAW resonator of the embodiment; the solid line represents the curve corresponding to the TF-SAW resonator of the comparative example.

[0091] As Figure 2 shown in the structure, the TF-SAW resonator corresponding to the embodiment has a better clutter removal effect, and the return loss spurious is eliminated.

[0092] Generally speaking, the technical solution of the present application suppresses energy leakage and transverse modes through lateral boundary design, using different sound speed changes, which provide an energy barrier in the high sound speed region at the lateral edge and limit the propagation of energy.

[0093] In an alternative embodiment of the present invention, the length of the recess 18 in the second direction Y is equal to the length of the metal bump 10 in the second direction Y, which is L1, and the width of the piston structure 17 in the second direction Y is L2.

[0094] Wherein, L1 = L2.

[0095] Specifically, in the embodiment of the present invention, 0.5×λ≤L2≤0.6×λ; λ is the wavelength of the sound wave propagating in the TF-SAW resonator. The values of L1 and L2 are adjusted according to the wavelength of the sound wave propagating in the TF-SAW resonator to meet the working requirements of different application scenarios of the TF-SAW resonator, and the technical effects that can be achieved by the technical solution of the present application are maximized.

[0096] In an alternative embodiment of the present invention, the width of the recess 18 in the first direction X is equal to the width of the metal bump 10 in the first direction X, which is L3.

[0097] Wherein, 0.2×λ≤L3≤0.25×λ.

[0098] Specifically, in the embodiment of the present invention, the value of L3 is adjusted according to the wavelength of the sound wave propagating in the TF-SAW resonator to meet the working requirements of different application scenarios of the TF-SAW resonator, and the technical effects that can be achieved by the technical solution of the present application are maximized. Exemplarily, when L3 = 0.25×λ compared with L3 = 0.2×λ, the energy rebound effect of the recess 18 is relatively weak.

[0099] In an alternative embodiment of the present invention, as Figure 1As shown, the piston structure 17 includes a first piston structure 171 and a second piston structure 172.

[0100] The second piston structure 172 on the first electrode finger 161 extends to the area where the first sub-bus bar 151 is located and is connected to the first sub-bus bar 151.

[0101] The second piston structure 172 on the second electrode finger 162 extends to the area where the second sub-bus bar 152 is located and is connected to the second sub-bus bar 152.

[0102] Specifically, in the embodiment of the present invention, the length of the first piston structure 171 in the first direction X is L4; where 0.4×λ ≤ L4 ≤ 0.6×λ; in the first direction X, the distance between the first piston structure 171 and the second piston structure 172 is L5; where 15×λ ≤ L5 ≤ 40×λ.

[0103] The area between the first piston structure 171 and the second piston structure 172 can be understood as the most effective acoustic area of the interdigital electrode 13, and the sound wave generated therein propagates in the second direction Y within this acoustic area.

[0104] Therefore, the length of the first piston structure 171 in the first direction X, and the distance between the first piston structure 171 and the second piston structure 172 in the first direction X, adjust the values of L4 and L5 according to the wavelength of the propagating sound wave in the TF-SAW resonator to meet the working requirements of different application scenarios of the TF-SAW resonator, and maximize the technical effects that can be achieved by the technical solution of this application.

[0105] In an alternative embodiment of the present invention, the maximum width of the bus bar 14 in the first direction X is L6; where 3×λ ≤ L6 ≤ 4×λ; the width of the sub-bus bar 15 in the first direction X is L7; where 0.2×λ ≤ L7 ≤ 0.25×λ; the width of the electrode finger 16 in the second direction Y is L8; where 0.2×λ ≤ L8 ≤ 0.25×λ; in the first direction X, the distance between the electrode finger 16 and the sub-bus bar 15 is L9; where 0.3μm ≤ L9 ≤ 0.7μm. In the first direction X, the minimum distance between the bus bar 14 and the sub-bus bar 15 is L10; where 1.5×λ ≤ L10 ≤ 2.2×λ; λ is the wavelength of the propagating sound wave in the TF-SAW resonator.

[0106] Specifically, in the embodiments of the present invention, the bus bar 14 can also be understood as a busbar conductive bar and serves as the electrical performance signal output terminal of the TF-SAW resonator; the sub-bus bar 15 can also be understood as a small busbar conductive bar. The two have the same length in the second direction Y and different widths in the first direction X, with the relationship of L7 < L6.

[0107] The gap region between the electrode finger bars 16 and the sub-bus bar 15 is the propagation region of the transverse mode. Therefore, different distances between the electrode finger bars 16 and the sub-bus bar 15 will result in different clutter suppression effects. In the embodiments of the present invention, it is defined that 0.3μm ≤ L9 ≤ 0.7μm to meet the working requirements of the TF-SAW resonator in different application scenarios and maximize the technical effects achievable by the technical solution of the present application.

[0108] Similarly, the gap region between the bus bar 14 and the sub-bus bar 15 is also the propagation region of the transverse mode. Therefore, different distances between the bus bar 14 and the sub-bus bar 15 will result in different clutter suppression effects. In the embodiments of the present invention, it is defined that 1.5×λ ≤ L10 ≤ 2.2×λ, and the value of L10 is adjusted according to the wavelength of the propagating acoustic wave in the TF-SAW resonator to meet the working requirements of the TF-SAW resonator in different application scenarios and maximize the technical effects achievable by the technical solution of the present application.

[0109] In an alternative embodiment of the present invention, referring to Figure 3 , Figure 3 is the second structural schematic diagram of a TF-SAW resonator provided by the embodiments of the present invention. The TF-SAW resonator provided by the embodiments of the present invention further includes:

[0110] A reflection grating 19 located at at least one end of the interdigital electrode 13 along the second direction Y. It should be noted that, in the embodiments of the present invention, the example of the reflection gratings 19 being provided at both ends of the interdigital electrode 13 along the second direction Y is used for illustration.

[0111] Specifically, in the embodiments of the present invention, a reflection grating 19 can also be provided at at least one end of the interdigital electrode 13 along the second direction Y, which is used to reflect the acoustic wave back to the resonant region, allowing the acoustic wave to continue to form resonance in the resonant region, thereby forming a better resonance effect and mode and improving the transmission performance of the TF-SAW resonator.

[0112] Among them, the width of the electrode finger bars in the reflection grating 19 in the second direction Y is L11; 0.2×λ ≤ L11 ≤ 0.25×λ.

[0113] In an alternative embodiment of the present invention, referring to Figure 4 , Figure 4A cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention. The TF-SAW resonator provided by the embodiment of the present invention further includes:

[0114] At least one dielectric layer located between the substrate 11 and the piezoelectric thin film layer 12.

[0115] Specifically, in the embodiment of the present invention, the at least one dielectric layer may include different arbitrary numbers of dielectric layers such as an insertion layer, a protective layer, an adjustment layer, a temperature compensation layer, a velocity-changing layer, etc., to form a stacked structure (Stack), so as to achieve various different technical effects. It should be noted that in the embodiment of the present invention, the dielectric layer including the first dielectric layer 20 and the second dielectric layer 21 is taken as an example for illustration, and one of the first dielectric layer 20 and the second dielectric layer 21 is a temperature compensation layer.

[0116] Among them, the temperature compensation layer can be selected as a SiO2 layer.

[0117] Based on the above embodiments of the present invention, in another embodiment of the present invention, a preparation method of a TF-SAW resonator is further provided. Refer to Figure 5 , Figure 5 A flowchart of a preparation method of a TF-SAW resonator provided by an embodiment of the present invention. The preparation method of the TF-SAW resonator provided by the embodiment of the present invention includes:

[0118] S101: As Figure 6 shown, provide a substrate 11.

[0119] S102: As Figure 7 shown, form a piezoelectric thin film layer 12 on one side of the substrate 11.

[0120] Specifically, in this step, at least one dielectric layer can be formed before forming the piezoelectric thin film layer 12 according to actual needs. It should be noted that, as Figure 7 shown, in the embodiment of the present invention, the dielectric layer including the first dielectric layer 20 and the second dielectric layer 21 is taken as an example for illustration, and one of the first dielectric layer 20 and the second dielectric layer 21 is a temperature compensation layer.

[0121] Among them, the thickness range of the piezoelectric thin film layer 12 is 0.5 μm - 0.8 μm.

[0122] S103: As Figure 8As shown, interdigital electrodes 13 are formed on the side of the piezoelectric thin film layer 12 facing away from the substrate 11; the interdigital electrodes 13 include bus bars 14, sub-bus bars 15, and electrode finger bars 16. The electrode finger bars 16 include an acoustic part A1 and an electrical part A2. The two ends of the electrical part A2 are respectively connected to the acoustic part A1 and the bus bar 14; the bus bar 14 includes a first bus bar 141 and a second bus bar 142 disposed opposite to each other in the first direction X. The sub-bus bar 15 includes a first sub-bus bar 151 and a second sub-bus bar 152 disposed opposite to each other in the first direction X; the electrode finger bars 16 include a first electrode finger bar 161 located on the first bus bar 141 and a second electrode finger bar 162 located on the second bus bar 142; the first sub-bus bar 151 is located between the first bus bar 141 and the second electrode finger bar 162 and is connected to the electrical part A2 of the first electrode finger bar 161; the second sub-bus bar 152 is located between the second bus bar 142 and the first electrode finger bar 161 and is connected to the electrical part A2 of the second electrode finger bar 162; the bus bar 14 and the sub-bus bar 15 extend along the second direction Y. The length extension direction of the electrode finger bar 16 is parallel to the first direction X. The first direction X and the second direction Y are parallel to the plane where the substrate 11 is located, and the first direction X and the second direction Y intersect; piston structures 17 at both ends of the acoustic part A1; metal bumps 10 and recesses 18; the bus bar 14 includes a first surface facing the sub-bus bar 15, and the sub-bus bar 15 includes a second surface facing the bus bar 14; one of the first surface and the second surface is provided with the metal bumps 10, and the other surface is provided with the recesses 18; the metal bumps 10 and the recesses 18 are arranged in one-to-one correspondence in the first direction X.

[0123] It should be noted that the thickness range of the interdigital electrodes 13 can be 0.05×λ - 0.1×λ.

[0124] Furthermore, as Figure 9 shown, an insulating layer 22 is formed in the target area of the interdigital electrodes 13. Exemplarily, the insulating layer 22 can be a functional layer that uses photoresist or other insulating materials to play an insulating role between the interdigital electrodes 13 and the subsequent wiring layer 23.

[0125] Among them, the thickness range of the insulating layer 22 can be about 1.5 μm.

[0126] Furthermore, as Figure 10 shown, the wiring layer 23 is prepared. The wiring layer 23 refers to a thick metal wiring layer that connects the conduction signals of each resonator, and the general material is an Al / Cu alloy.

[0127] Among them, the thickness range of the wiring layer 23 can be about 2.5 μm.

[0128] Further, as Figure 11 shown, a surface protection layer 24 is prepared. The surface protection layer 24 realizes the protection of the interdigital electrodes 13 and the wiring layer 23, and the material of the surface protection layer 24 includes but is not limited to SiNx material.

[0129] Among them, the thickness range of the surface protection layer 24 can be about 5 nm - 20 nm.

[0130] Further, as Figure 4 shown, the surface protection layer 24 is etched to form a groove to expose a part of the surface of the wiring layer 23, and pads 25 are arranged in the groove to realize the electrical connection between the TF-SAW resonator and external components.

[0131] Optionally, based on the above embodiments of the present invention, in another embodiment of the present invention, a filter is further provided, and the filter includes the TF-SAW resonator described in the above embodiments.

[0132] The filter has the same effect as the TF-SAW resonator in the above embodiments.

[0133] The above has introduced in detail a TF-SAW resonator, its manufacturing method, and a filter provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

[0134] It should be noted that each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts among the various embodiments can be referred to each other.

[0135] It should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements inherent to the process, method, article or device, but also other elements inherent to these process, method, article or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0136] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A TF-SAW resonator, characterized in that, The TF-SAW resonator includes: a substrate; a piezoelectric thin film layer located on one side of the substrate; interdigital electrodes located on the side of the piezoelectric thin film layer facing away from the substrate; the interdigital electrodes include bus bars, sub-bus bars, and electrode finger bars, the electrode finger bars include acoustic parts and electrical parts, and both ends of the electrical part are respectively connected to the acoustic part and the bus bar; the bus bars include a first bus bar and a second bus bar oppositely arranged in a first direction, the sub-bus bars include a first sub-bus bar and a second sub-bus bar oppositely arranged in the first direction; the electrode finger bars include a first electrode finger bar located on the first bus bar and a second electrode finger bar located on the second bus bar; the first sub-bus bar is located between the first bus bar and the second electrode finger bar and is connected to the electrical part of the first electrode finger bar; the second sub-bus bar is located between the second bus bar and the first electrode finger bar and is connected to the electrical part of the second electrode finger bar; the bus bars and the sub-bus bars extend in a second direction, the length extension direction of the electrode finger bars is parallel to the first direction, the first direction and the second direction are parallel to the plane where the substrate is located, and the first direction and the second direction intersect; piston structures located at both ends of the acoustic part; metal bumps and depressions; the bus bar includes a first surface facing the sub-bus bar, the sub-bus bar includes a second surface facing the bus bar; one of the first surface and the second surface is provided with the metal bumps, and the other surface is provided with the depressions; the metal bumps and the depressions are arranged in one-to-one correspondence in the first direction.

2. The TF-SAW resonator according to claim 1, wherein The first surface is provided with the depressions, and the second surface is provided with the metal bumps; In the first direction, the depressions on the first bus bar, the metal bumps on the first sub-bus bar, and the piston structures on the second electrode finger bar are correspondingly arranged; In the first direction, the depressions on the second bus bar, the metal bumps on the second sub-bus bar, and the piston structures on the first electrode finger bar are correspondingly arranged.

3. The TF-SAW resonator according to claim 1, wherein The length of the depression in the second direction is equal to the length of the metal bump in the second direction, which is L1, and the width of the piston structure in the second direction is L2; wherein, L1 = L2.

4. The TF-SAW resonator according to claim 1, wherein The width of the depression in the first direction is equal to the width of the metal bump in the first direction, which is L3; wherein, 0.2×λ ≤ L3 ≤ 0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

5. The TF-SAW resonator according to claim 1, characterized in that, The width of the piston structure in the second direction is L2; wherein, 0.5×λ ≤ L2 ≤ 0.6×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

6. The TF-SAW resonator according to claim 1, characterized in that, The piston structure includes a first piston structure and a second piston structure; The second piston structure on the first electrode finger bar extends to the area where the first sub-bus bar is located and is connected to the first sub-bus bar; The second piston structure on the second electrode finger extends to the area where the second sub-bus bar is located and is connected to the second sub-bus bar.

7. The TF-SAW resonator according to claim 6, wherein, The length of the first piston structure in the first direction is L4; where 0.4×λ ≤ L4 ≤ 0.6×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

8. The TF-SAW resonator according to claim 6, wherein In the first direction, the distance between the first piston structure and the second piston structure is L5; where 15×λ ≤ L5 ≤ 40×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

9. The TF-SAW resonator according to claim 1, wherein The maximum width of the bus bar in the first direction is L6; where 3×λ ≤ L6 ≤ 4×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

10. The TF-SAW resonator according to claim 1, characterized in that, The width of the sub-bus bar in the first direction is L7; where 0.2×λ ≤ L7 ≤ 0.25×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

11. The TF-SAW resonator according to claim 1, characterized in that, The width of the electrode finger in the second direction is L8; where 0.2×λ ≤ L8 ≤ 0.25×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

12. The TF-SAW resonator according to claim 1, wherein, In the first direction, the distance between the electrode finger and the sub-bus bar is L9; where 0.3μm ≤ L9 ≤ 0.7μm.

13. The TF-SAW resonator according to claim 1, wherein, In the first direction, the minimum distance between the bus bar and the sub-bus bar is L10; where 1.5×λ ≤ L10 ≤ 2.2×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

14. The TF-SAW resonator according to any one of claims 1-13, characterized in that, The TF-SAW resonator further includes: A reflection grating located at at least one end of the interdigital electrode in the second direction.

15. The TF-SAW resonator according to claim 14, wherein The width of the electrode finger in the second direction in the reflection grating is L11; where 0.2×λ ≤ L11 ≤ 0.25×λ; λ is the wavelength of the propagating acoustic wave in the TF-SAW resonator.

16. The TF-SAW resonator according to any one of claims 1-13, characterized in that, The TF-SAW resonator further includes: At least one dielectric layer located between the substrate and the piezoelectric thin film layer.

17. The TF-SAW resonator according to claim 16, characterized in that, The at least one dielectric layer includes a temperature compensation layer.

18. A preparation method of a TF-SAW resonator, characterized in that, The method for manufacturing the TF-SAW resonator includes: Providing a substrate; Forming a piezoelectric thin film layer on one side of the substrate; Form interdigital electrodes on the side of the piezoelectric thin film layer facing away from the substrate; the interdigital electrodes include bus bars, sub-bus bars, and electrode finger bars, the electrode finger bars include acoustic parts and electrical parts, and the two ends of the electrical parts are respectively connected to the acoustic parts and the bus bars; the bus bars include a first bus bar and a second bus bar oppositely arranged in a first direction, the sub-bus bars include a first sub-bus bar and a second sub-bus bar oppositely arranged in the first direction; the electrode finger bars include a first electrode finger bar located on the first bus bar and a second electrode finger bar located on the second bus bar; the first sub-bus bar is located between the first bus bar and the second electrode finger bar and is connected to the electrical part of the first electrode finger bar; the second sub-bus bar is located between the second bus bar and the first electrode finger bar and is connected to the electrical part of the second electrode finger bar; the bus bars and the sub-bus bars extend in a second direction, the length extension direction of the electrode finger bars is parallel to the first direction, the first direction and the second direction are parallel to the plane where the substrate is located, and the first direction and the second direction intersect; piston structures at both ends of the acoustic part; metal bumps and depressions; the bus bars include a first surface facing the sub-bus bars, the sub-bus bars include a second surface facing the bus bars; one of the first surface and the second surface is provided with the metal bumps, and the other surface is provided with the depressions; the metal bumps and the depressions are arranged in one-to-one correspondence in the first direction.

19. A filter, characterized in that, The filter includes the TF-SAW resonator according to any one of claims 1-17.

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