A TF-SAW resonator and its preparation method, and filter

Abstract

The present invention provides a TF-SAW resonator, a preparation method thereof, and a filter, relating to the field of semiconductor technology. The interdigitated electrode includes a piston structure, a sub-bus bar, and a recess. The piston structure is located at both ends of the acoustic part. It can be understood that the end region of the acoustic part on the electrode finger is provided with a piston structure. By changing the sound velocity of the end region, a larger sound velocity difference is achieved, so that the transverse mode is reflected in different directions to avoid resonance and energy dissipation. Sub-bus bars and recesses are then arranged in sequence on the propagation path of the transverse mode. By creating a sound velocity difference, clutter interference is eliminated, so as to suppress clutter interference to the greatest extent, improve the Q value, improve the performance of standing waves in the passband, improve insertion loss, etc., and thus improve the performance of the TF-SAW resonator.

Description

Technical Field

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

[0002] In current TF-SAW (Thin-Film Surface Acoustic Wave) product designs, laterally propagating sound waves can cause lateral resonant modes in the TF-SAW resonator, reducing the performance of the TF-SAW resonator.

[0003] Therefore, how to improve the performance of TF-SAW resonators is the top priority in today's resonator design. Summary of the Invention

[0004] In view of the above problems, this application provides a TF-SAW resonator and its preparation method, as well as a filter, to achieve the purpose of improving the performance of the TF-SAW resonator. The specific solution is as follows:

[0005] A first aspect of the present application provides a TF-SAW resonator, the TF-SAW resonator comprising:

[0006] substrate;

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

[0008] an interdigitated electrode located on a side of the piezoelectric film layer facing away from the substrate; the interdigitated electrode comprises a bus bar, a sub-bus bar, and an electrode finger, the electrode finger comprising an acoustic portion and an electrical portion, the two ends of the electrical portion being connected to the acoustic portion and the bus bar, respectively; the bus bar comprises a first bus bar and a second bus bar arranged opposite to each other in a first direction, the sub-bus bar comprises a first sub-bus bar and a second sub-bus bar arranged opposite to each other in the first direction; the electrode finger comprises a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar; the first sub-bus bar is located between the first bus bar and the second electrode finger and is connected to the electrical portion of the first electrode finger; the second sub-bus bar is located between the second bus bar and the first electrode finger and is connected to the electrical portion of the second electrode finger; the bus bar and the sub-bus bar extend along a second direction, the length extension direction of the electrode finger is parallel to the first direction, the first direction and the second direction are parallel to the plane of the substrate, and the first direction and the second direction intersect;

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

[0010] The recess includes a first recess located on a surface of the bus bar facing the sub-bus bar, and / or includes a second recess located on a surface of the sub-bus bar facing the bus bar.

[0011] Preferably, in the above-mentioned TF-SAW resonator, when the recess includes the first recess, in the first direction, the first recess on the first bus bar is arranged corresponding to the piston structure on the second electrode finger, and the first recess on the second bus bar is arranged corresponding to the piston structure on the first electrode finger;

[0012] When the recess includes the second recess, in the first direction, the second recess on the first sub-bus bar is arranged corresponding to the piston structure on the second electrode finger, and the second recess on the second sub-bus bar is arranged corresponding to the piston structure on the first electrode finger;

[0013] When the recess includes the first recess and the second recess, the first recess and the second recess are arranged in a one-to-one correspondence in the first direction; in the first direction, the first recess on the first bus bar, the second recess on the first sub-bus bar, and the piston structure on the second electrode finger are arranged in a corresponding manner; in the first direction, the first recess on the second bus bar, the second recess on the second sub-bus bar, and the piston structure on the first electrode finger are arranged in a corresponding manner.

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

[0015] Among them, L1=L2.

[0016] Preferably, in the above TF-SAW resonator, the width of the recess in the first direction 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 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 busbar 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 maximum width of the sub-busbar 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] Among them, 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 comprises:

[0038] A reflection grid is located at at least one end of the interdigitated electrodes along the second direction.

[0039] Preferably, in the above TF-SAW resonator, the width of the electrode fingers in the reflective 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 comprises:

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

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

[0044] A second aspect of the present application provides a method for preparing a TF-SAW resonator, the method comprising:

[0045] providing a substrate;

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

[0047] An interdigitated electrode is formed on the side of the piezoelectric film layer facing away from the substrate; the interdigitated electrode includes a bus bar, a sub-bus bar and an electrode finger bar, the electrode finger bar includes 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 opposite to each other in a first direction, and the sub-bus bar includes a first sub-bus bar and a second sub-bus bar arranged opposite to each other in the first direction; the electrode finger bar includes 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 electrically connected to the first bus bar. The electrical part of the first electrode finger is connected; the second sub-bus is located between the second bus and the first electrode finger, and is connected to the electrical part of the second electrode finger; the bus and the sub-bus extend along a second direction, the length extension direction of the electrode finger 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; a piston structure is located at both ends of the acoustic part; a depression, the depression includes a first depression located on the surface of the bus bar facing the sub-bus bar, and / or includes a second depression located on the surface of the sub-bus bar facing the bus bar.

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

[0049] With the help of the above technical solution, the present application provides a TF-SAW resonator and its preparation method, and a filter. The interdigitated electrode includes a piston structure, a sub-bus bar and a recess. The piston structure is located at both ends of the acoustic part. It can be understood that the end area of ​​the acoustic part on the electrode finger is provided with a piston structure. By changing the sound velocity of the end area, a larger sound velocity difference is achieved, so that the transverse mode is reflected in different directions to avoid resonance and energy dissipation; on the propagation path of the transverse mode, sub-bus bars and recesses are arranged in sequence to eliminate clutter interference by causing a sound velocity difference, so as to suppress clutter interference to the greatest extent, improve the Q value, improve the performance of standing waves in the passband, improve the insertion loss, etc., thereby improving the performance of the TF-SAW resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the originals and elements are not necessarily drawn to scale.

[0051] Figure 1One of the structural schematic diagrams of a TF-SAW resonator provided in an embodiment of the present invention;

[0052] Figure 2 A second structural diagram of a TF-SAW resonator provided in an embodiment of the present invention;

[0053] Figure 3 A third structural diagram of a TF-SAW resonator provided in an embodiment of the present invention;

[0054] Figure 4 A schematic diagram showing the effect of different TF-SAW resonators on clutter removal in Example 1 and a comparative example provided in an embodiment of the present invention;

[0055] Figure 5 A schematic diagram showing the effect of different TF-SAW resonators on clutter removal in Example 2 and a comparative example provided in an embodiment of the present invention;

[0056] Figure 6 A schematic diagram showing the effect of different TF-SAW resonators on clutter removal in Example 3 and a comparative example provided in an embodiment of the present invention;

[0057] Figure 7 A fourth structural diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0058] Figure 8 A fifth structural diagram of a TF-SAW resonator provided in an embodiment of the present invention;

[0059] Figure 9 A sixth structural diagram of a TF-SAW resonator provided in an embodiment of the present invention;

[0060] Figure 10 A schematic cross-sectional view of a TF-SAW resonator provided in an embodiment of the present invention;

[0061] Figure 11 A schematic flow chart of a method for preparing a TF-SAW resonator provided in an embodiment of the present invention;

[0062] Figure 12 One of the partial cross-sectional schematic diagrams of a TF-SAW resonator provided by an embodiment of the present invention;

[0063] Figure 13 A second partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0064] Figure 14 A third partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0065] Figure 15 A fourth partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0066] Figure 16 A fifth partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention;

[0067] Figure 17 The sixth partial cross-sectional schematic diagram of a TF-SAW resonator provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0068] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation methods of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0069] Surface acoustic wave resonators and filters are acoustic devices widely used in the radio frequency field. They combine low insertion loss with excellent suppression performance in a relatively small size. They are used to filter out interference from interfering signals, attenuating certain frequency components while allowing only specific frequency components to pass through. They are the technical foundation for utilizing the wireless spectrum as a non-renewable and scarce resource. The specific principle can be simply understood as based on the piezoelectric properties of piezoelectric materials. Input and output transducers such as interdigital transducers are used to convert electrical signals into mechanical energy, which is then processed and converted back into electrical signals to amplify the desired signal, filter out noise, and improve signal quality. They are widely used in various wireless communication devices.

[0070] Currently, filters are primarily categorized as SAW filters and BAW (Bulk Acoustic Wave) filters. Surface acoustic waves (SAWs) are elastic waves that originate and propagate on the surface of a piezoelectric substrate, with their amplitude decreasing rapidly with depth. SAW filters are less expensive to manufacture than BAW filters and are primarily used in low-frequency bands. They offer low insertion loss, good rejection, and high temperature sensitivity.

[0071] It should also be noted that SAW filters have their limitations, one of which is their susceptibility to temperature fluctuations. As the temperature rises, the stiffness of the base material decreases, and the speed of sound also decreases. In other words, SAW filters suffer from temperature drift, meaning their frequency will drift with the operating temperature. Therefore, based on traditional SAW filters, TC-SAW (Temperature Compensated SAW) filters have emerged. These filters, or temperature-compensated SAW filters, primarily utilize the opposite temperature elasticity of the temperature compensation layer (e.g., the SiO2 layer) and the piezoelectric film layer to compensate for temperature drift.

[0072] Furthermore, SAW filters also have product designs such as TF-SAW filters, in which the filter design often uses resonators as basic units, which can form the corresponding topology and amplify the specified frequency component signal.

[0073] For TC-SAW resonators, ordinary SAW resonators, or TF-SAW resonators, the surface acoustic wave resonator will have a lateral resonance mode due to the acoustic waves propagating laterally in the surface acoustic wave resonator, that is, the noise appearing in and near the passband. This noise will increase the loss of the surface acoustic wave resonator, cause the Q value to fluctuate significantly, and reduce the performance of the surface acoustic wave resonator.

[0074] It should be noted that the embodiments of the present invention are mainly described with respect to TF-SAW resonators. The embodiments of the present invention provide a TF-SAW resonator, a method for preparing the same, and a filter. By combining a piston structure, a sub-bus bar, and a recess, the suppression of transverse mode spurious signals is enhanced, thereby achieving greater suppression of spurious mode interference, increasing the Q value, improving the standing wave performance within the passband, and enhancing the performance of the TF-SAW resonator.

[0075] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0076] It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation to the present application.

[0077] refer to Figure 1 , Figure 1 One of the structural diagrams of a TF-SAW resonator provided in an embodiment of the present invention, refer to Figure 2 , Figure 2 The second structural diagram of a TF-SAW resonator provided by an embodiment of the present invention, refer to Figure 3 , Figure 3This is a third structural diagram of a TF-SAW resonator provided by an embodiment of the present invention. The TF-SAW resonator provided by an embodiment of the present invention includes: a substrate 11.

[0078] The piezoelectric film layer 12 is located on one side of the substrate 11 .

[0079] The interdigitated electrode 13 is located on the side of the piezoelectric film layer 12 away from the substrate 11; the interdigitated electrode 13 includes a bus bar 14, a sub-bus bar 15 and an electrode finger 16, the electrode finger 16 includes an acoustic part A1 and an electrical part A2, and 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 arranged opposite to each other in a first direction X, the sub-bus bar 15 includes a first sub-bus bar 151 and a second sub-bus bar 152 arranged opposite to each other in the first direction X; the electrode finger 16 includes a first electrode finger 161 located on the first bus bar 141 and a second electrode finger 162 located on the second bus bar 141. The second electrode finger 162 on the bus bar 142; the first sub-bus bar 151 is located between the first bus bar 141 and the second electrode finger 162, and is connected to the electrical portion A2 of the first electrode finger 161; the second sub-bus bar 152 is located between the second bus bar 142 and the first electrode finger 161, and is connected to the electrical portion A2 of the second electrode finger 162; the bus bar 14 and the sub-bus bar 15 extend along the second direction Y, the length of the electrode finger 16 extends parallel to the first direction X, the first direction X and the second direction Y are parallel to the plane of the substrate 11, and the first direction X and the second direction Y intersect. It should be noted that in this embodiment of the present invention, the first direction X and the second direction Y are perpendicular to each other.

[0080] The piston structures 17 are located at both ends of the acoustic part A1.

[0081] The recess 18 includes a first recess 181 located on the surface of the bus bar 14 facing the sub-bus bar 15 , and / or includes a second recess 182 located on the surface of the sub-bus bar 15 facing the bus bar 14 .

[0082] Specifically, in the embodiment of the present invention, the substrate 11 serves as a support structure, and its material can be selected from lithium tantalate, lithium niobate, aluminum nitride, sapphire, spinel, single crystal silicon, silicon carbide, or quartz. The piezoelectric film layer 12 is made of a piezoelectric material, and its material can be lithium tantalate (LT) or lithium niobate (LN). The interdigital electrodes are typically made of a metal material, and its material can be a low-resistivity material such as Cu, Al, Au, Ti, Cr, or Pt.

[0083] The length extension direction of the electrode finger 16 is parallel to the first direction X, and the multiple first electrode fingers 161 on the first bus bar 141 are arranged at intervals in the second direction Y, and the multiple second electrode fingers 162 on the second bus bar 142 are arranged at intervals in the second direction Y, and the multiple first electrode fingers 161 on the first bus bar 141 and the multiple 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 the multiple first electrode fingers 161 on the first bus bar 141 and the second bus bar 142, and there is a gap between the multiple 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 fingers 16 are distributed in a manner similar to crossing fingers, forming a so-called interdigitated electrode 13. When the first bus bar 141 and its first electrode fingers 161 function as a transmitter, the second bus bar 142 and its second electrode fingers 162 function as a receiver. Conversely, when the first bus bar 141 and its first electrode fingers 161 function as a receiver, the second bus bar 142 and its second electrode fingers 162 function as a transmitter. The transmitter converts electrical signals into acoustic waves, which primarily propagate along the surface of the piezoelectric film layer 12. The receiver converts the received acoustic waves into electrical signals for output, thereby achieving filtering.

[0084] like Figure 1 As shown, the sound velocity of the gap area between the electrode finger 16 and the sub-bus bar 15, and the gap area between the sub-bus bar 15 and the bus bar 14 is W1; the sound velocity of the area where the sub-bus bar 15 is located, and the area where the first recess 181 is not provided on the bus bar 14 is located is W2; the sound velocity of the area where the electrode finger 16 between the piston structures 17 is located is W3; the sound velocity of the area where the first recess 181 is provided on the bus bar 14 is W4; the sound velocity of the area where the piston structure 17 is located is W5; there is a relationship of W1>W2>W3>W4>W5.

[0085] like Figure 2As shown, the sound velocity of the gap area between the electrode finger 16 and the sub-bus bar 15, and the gap area between the sub-bus bar 15 and the bus bar 14 is P1; the sound velocity of the area where the second recess 182 is set on the sub-bus bar 15 is P2; the sound velocity of the area where the bus bar 14 is located, and the sound velocity of the area where the second recess 182 is not set on the sub-bus bar 15 is P3; the sound velocity of the area where the electrode finger 16 between the piston structures 17 is located is P4; the sound velocity of the area where the piston structure 17 is located is P5; there is a relationship of P1>P2>P3>P4>P5.

[0086] like Figure 3 As shown, the sound velocity of the gap area between the electrode finger 16 and the sub-bus bar 15, and the gap area between the sub-bus bar 15 and the bus bar 14 is V1; the sound velocity of the area where the second recess 182 is set on the sub-bus bar 15 is V2; the sound velocity of the area where the second recess 182 is not set on the sub-bus bar 15, and the sound velocity of the area where the first recess 181 is not set on the bus bar 14 are V3; the sound velocity of the area where the electrode finger 16 between the piston structures 17 is V4; the sound velocity of the area where the first recess 181 is set on the bus bar 14 is V5; the sound velocity of the area where the piston structure 17 is V6; there is a relationship of V1>V2>V3>V4>V5>V6.

[0087] In the embodiment of the present invention, the interdigitated electrode 13 further comprises a piston structure 17, a sub-bus bar 15, and a recess 18. The piston structure 17 is located at both ends of the acoustic portion A1. It is understood that the piston structure 17 is provided at the end region of the acoustic portion A1 on the electrode finger 16. By changing the sound velocity in this end region, a greater sound velocity difference is achieved, thereby causing the transverse mode to reflect in different directions to avoid resonance and energy dissipation.

[0088] The first sub-bus bar 151 in the sub-bus bar 15 is located between the first bus bar 141 and the second electrode finger 162, and is connected to the electrical part A2 of the first electrode finger 161; the second sub-bus bar 152 is located between the second bus bar 142 and the first electrode finger 161, and is connected to the electrical part A2 of the second electrode finger 162.

[0089] The recess 18 includes a first recess 181 and / or a second recess 182, wherein the first recess 181 is located on the side surface of the busbar 14 facing the sub-busbar 15, and at this time a tooth-shaped structure is formed on the side surface of the busbar 14 facing the sub-busbar 15; the second recess 182 is located on the side surface of the sub-busbar 15 facing the busbar 14, and at this time a tooth-shaped structure is formed on the side surface of the sub-busbar 15 facing the busbar 14.

[0090] When the recess 18 includes the first recess 181, in the first direction X, the first recess 181 on the first bus bar 141 is arranged corresponding to the piston structure 17 on the second electrode finger 162, and the first recess 181 on the second bus bar 142 is arranged corresponding to the piston structure 17 on the first electrode finger 161; when the recess 18 includes the second recess 182, in the first direction X, the second recess 182 on the first sub-bus bar 151 is arranged corresponding to the piston structure 17 on the second electrode finger 162, and the second recess 182 on the second sub-bus bar 152 is arranged corresponding to the piston structure 17 on the first electrode finger 161.

[0091] When the recess 18 includes the first recess 181 and the second recess 182, the first recess 181 and the second recess 182 are arranged in one-to-one correspondence in the first direction X; in the first direction X, the first recess 181 on the first bus bar 141, the second recess 182 on the first sub-bus bar 151 and the piston structure 17 on the second electrode finger 162 are arranged in correspondence; in the first direction X, the first recess 181 on the second bus bar 142, the second recess 182 on the second sub-bus bar 152 and the piston structure 17 on the first electrode finger 161 are arranged in correspondence.

[0092] It can be understood that on the propagation path of the lateral mode, a sub-bus bar 15 and a recess 18 are set to change the sound speed in their respective areas, and eliminate clutter interference by creating a sound speed difference. The sub-bus bar 15 can rebound the energy leaked from the acoustic area, and the design of the recess 18 can reduce the rebound effect of the area where the recess 18 is located on the energy, avoiding excessive energy from being rebounded back to the acoustic area, so as to suppress clutter interference to the greatest extent, improve the Q value, improve the performance of standing waves in the passband, improve the insertion loss, etc., thereby improving the performance of the TF-SAW resonator.

[0093] Furthermore, in the technical solution of the present application, when the recess 18 includes a first recess 181 on the bus bar 14 and a second recess 182 on the sub-bus bar 15, compared with the technical solution of setting the first recess 181 on the bus bar 14 or the second recess 182 on the sub-bus bar 15, it is not a simple combination of setting the first recess 181 on the bus bar 14 and setting the second recess 182 on the sub-bus bar 15, but it is necessary to ensure that the first recess 181 and the second recess 182 are set one by one in the first direction X, thereby maximizing the energy rebound effect of the area where the recess 18 is located, thereby maximizing the performance of the TF-SAW resonator.

[0094] The following further illustrates the technical effects that can be achieved by the technical solution of this application in a comparative manner.

[0095] Comparative example: The interdigital electrodes in the TF-SAW resonator only include bus bars, electrode fingers, and dummy electrode fingers.

[0096] Example 1: Figure 1 The TF-SAW resonator shown.

[0097] Example 2: Figure 2 The TF-SAW resonator shown.

[0098] Example 3: Figure 3 The TF-SAW resonator shown.

[0099] refer to Figure 4 , Figure 4 A schematic diagram showing the effect of different TF-SAW resonators on noise removal in Example 1 and a comparative example provided by the present invention. The dotted line represents the curve corresponding to the TF-SAW resonator in Example 1, and the solid line represents the curve corresponding to the TF-SAW resonator in the comparative example.

[0100] like Figure 4 From the structure shown, it can be seen that the TF-SAW resonator corresponding to the first embodiment has a better effect on removing clutter.

[0101] refer to Figure 5 , Figure 5 A schematic diagram showing the effect of different TF-SAW resonators on noise removal in Example 2 and a comparative example provided by the present invention. The dotted line represents the curve corresponding to the TF-SAW resonator in Example 2, and the solid line represents the curve corresponding to the TF-SAW resonator in the comparative example.

[0102] like Figure 5 From the structure shown, it can be seen that the TF-SAW resonator corresponding to the second embodiment has a better effect in removing clutter.

[0103] refer to Figure 6 , Figure 6 A schematic diagram showing the effect of different TF-SAW resonators on noise removal in Example 3 and a comparative example provided by the present invention. The dotted line represents the curve corresponding to the TF-SAW resonator in Example 3; the solid line represents the curve corresponding to the TF-SAW resonator in the comparative example.

[0104] like Figure 6 From the structure shown, it can be seen that the TF-SAW resonator corresponding to the third embodiment has a better effect on removing clutter.

[0105] In general, the technical solution of the present application suppresses energy leakage and lateral modes by using different sound speed changes through lateral boundary design. These high sound speed areas at the lateral edges provide energy barriers and limit the propagation of energy.

[0106] In an optional embodiment of the present invention, the length of the recess 18 in the second direction Y is L1, and the width of the piston structure 17 in the second direction Y is L2.

[0107] Among them, L1=L2.

[0108] Specifically, in this embodiment of the present invention, 0.5×λ≤L2≤0.6×λ, where 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 operating requirements of the TF-SAW resonator in different application scenarios and maximize the technical effects achievable by the technical solution of this application.

[0109] In an optional embodiment of the present invention, the width of the recess 18 in the first direction X is L3.

[0110] Among them, 0.2×λ≤L3≤0.25×λ.

[0111] Specifically, in the embodiments of the present invention, the value of L3 is adjusted according to the wavelength of the sound waves propagating in the TF-SAW resonator to meet the working requirements of the TF-SAW resonator in different application scenarios and to maximize the technical effects achievable by the technical solution of the present application. For example, when L3 = 0.25 × λ compared to L3 = 0.2 × λ, the energy rebound effect of the recess 18 is relatively weaker.

[0112] In an optional embodiment of the present invention, Figure 1-Figure 3 As shown, the piston structure 17 includes a first piston structure 171 and a second piston structure 172 .

[0113] 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 .

[0114] 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 .

[0115] Specifically, in the embodiment of the present invention, the length of the first piston structure 171 in the first direction X is L4; wherein 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; wherein 15×λ≤L5≤40×λ.

[0116] 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 waves generated by the interdigital electrode 13 propagate along the second direction Y in the acoustic area.

[0117] 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, are adjusted according to the wavelength of the sound waves propagating in the TF-SAW resonator to adjust the values ​​of L4 and L5 so as to meet the working requirements of the TF-SAW resonator in different application scenarios and maximize the technical effects that can be achieved by the technical solution of this application.

[0118] In an optional embodiment of the present invention, the maximum width of the busbar 14 in the first direction X is L6, where 3×λ≤L6≤4×λ. The maximum width of the sub-busbar 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 spacing between the electrode finger 16 and the sub-busbar 15 is L9, where 0.3μm≤L9≤0.7μm. In the first direction X, the minimum spacing between the busbar 14 and the sub-busbar 15 is L10, where 1.5×λ≤L10≤2.2×λ. λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

[0119] Specifically, in this embodiment of the present invention, busbar 14 can also be understood as a busbar conductive bar, serving as an output terminal for the electrical performance signal of the TF-SAW resonator; sub-busbar 15 can also be understood as a small busbar conductive bar. Both have the same length in the second direction Y, but differ in width in the first direction X, with the relationship L7 < L6.

[0120] The gap between the electrode fingers 16 and the sub-busbar 15 is the propagation area of ​​the transverse mode. Therefore, different distances between the electrode fingers 16 and the sub-busbar 15 will have different effects on suppressing clutter. In the embodiment of the present invention, 0.3μm≤L9≤0.7μm is specified to meet the operating requirements of TF-SAW resonators in different application scenarios and maximize the technical effects achievable by the technical solution of this application.

[0121] Similarly, the gap between busbar 14 and sub-busbar 15 also forms the propagation area for the transverse mode. Therefore, different distances between busbar 14 and sub-busbar 15 will result in different noise suppression effects. In this embodiment of the present invention, 1.5×λ≤L10≤2.2×λ is defined. The value of L10 is adjusted based on the wavelength of the acoustic wave propagating in the TF-SAW resonator to meet the operating requirements of the TF-SAW resonator in different application scenarios and to maximize the technical effects achievable by the technical solution of this application.

[0122] In an optional embodiment of the present invention, reference Figure 7 , Figure 7 The fourth structural diagram of a TF-SAW resonator provided by an embodiment of the present invention, referring to Figure 8 , Figure 8 A fifth structural diagram of a TF-SAW resonator provided in an embodiment of the present invention; Figure 9 This is a sixth structural diagram of a TF-SAW resonator provided by an embodiment of the present invention. The TF-SAW resonator provided by an embodiment of the present invention also includes:

[0123] The reflective grating 19 is located at at least one end of the interdigital electrode 13 along the second direction Y. It should be noted that in the embodiment of the present invention, the reflective grating 19 is provided at both ends of the interdigital electrode 13 along the second direction Y as an example for description.

[0124] Specifically, in an embodiment of the present invention, a reflection grating 19 can be further provided at at least one end of the interdigitated electrode 13 along the second direction Y to reflect the sound waves back to the resonance area, allowing the sound waves to continue to resonate in the resonance area, thereby forming a better resonance effect and mode, and improving the transmission performance of the TF-SAW resonator.

[0125] The width of the electrode fingers in the reflective grating 19 in the second direction Y is L11; 0.2×λ≤L11≤0.25×λ.

[0126] In an optional embodiment of the present invention, reference Figure 10 , Figure 10 A schematic cross-sectional view of a TF-SAW resonator provided in an embodiment of the present invention. The TF-SAW resonator provided in an embodiment of the present invention further includes:

[0127] At least one dielectric layer is located between the substrate 11 and the piezoelectric film layer 12 .

[0128] Specifically, in the embodiments of the present invention, the at least one dielectric layer may include any number of dielectric layers, such as an insertion layer, a protective layer, a regulating layer, a temperature compensation layer, and a speed-shifting layer, to form a stacked structure, thereby achieving a variety of different technical effects. It should be noted that in the embodiments of the present invention, the dielectric layer includes a first dielectric layer 20 and a second dielectric layer 21, and one of the first dielectric layer 20 and the second dielectric layer 21 is a temperature compensation layer.

[0129] The temperature compensation layer may be a SiO2 layer.

[0130] Based on the above embodiment of the present invention, another embodiment of the present invention further provides a method for preparing a TF-SAW resonator, referring to Figure 11 , Figure 11 A schematic diagram of a process for preparing a TF-SAW resonator provided in an embodiment of the present invention. The process for preparing a TF-SAW resonator provided in an embodiment of the present invention includes:

[0131] S101: If Figure 12 As shown, a substrate 11 is provided.

[0132] S102: Figure 13 As shown, a piezoelectric film layer 12 is formed on one side of the substrate 11 .

[0133] Specifically, in this step, at least one dielectric layer may be formed before forming the piezoelectric film layer 12 according to actual needs. It should be noted that, if Figure 13 As shown, in the embodiment of the present invention, the dielectric layer includes a first dielectric layer 20 and a second dielectric layer 21 as an example for description, and one of the first dielectric layer 20 and the second dielectric layer 21 is a temperature compensation layer.

[0134] The thickness of the piezoelectric film layer 12 is in the range of 0.5 μm to 0.8 μm.

[0135] S103: If Figure 14As shown, an interdigitated electrode 13 is formed on the side of the piezoelectric film layer 12 facing away from the substrate 11; the interdigitated electrode 13 includes a bus bar 14, a sub-bus bar 15 and an electrode finger 16, the electrode finger 16 includes an acoustic part A1 and an electrical part A2, and 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 arranged opposite to each other in a first direction X, and the sub-bus bar 15 includes a first sub-bus bar 151 and a second sub-bus bar 152 arranged opposite to each other in the first direction X; the electrode finger 16 includes a first electrode finger 161 located on the first bus bar 141 and a second electrode finger 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 1 62, and is connected to the electrical part A2 of the first electrode finger 161; the second sub-bus bar 152 is located between the second bus bar 142 and the first electrode finger 161, and is connected to the electrical part A2 of the second electrode finger 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 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; a piston structure 17 is located at both ends of the acoustic part A1; a recess 18, the recess 18 includes a first recess 181 located on the surface of the bus bar 14 facing the sub-bus bar 15, and / or includes a second recess 182 located on the surface of the sub-bus bar 15 facing the bus bar 14.

[0136] It should be noted that the thickness of the interdigital electrode 13 may be in the range of 0.05×λ-0.1×λ.

[0137] Further, such as Figure 15 As shown, an insulating layer 22 is formed in the target area of ​​the interdigital electrodes 13. For example, the insulating layer 22 can be a functional layer using photoresist or other insulating materials to play an insulating role between the interdigital electrodes 13 and the subsequent wiring layer 23.

[0138] The thickness of the insulating layer 22 may be about 1.5 μm.

[0139] Further, such as Figure 16 As shown, a wiring layer 23 is prepared. The wiring layer 23 refers to a thick metal wiring layer that conducts signals between the resonators, and is generally made of Al / Cu alloy.

[0140] The thickness of the wiring layer 23 may be about 2.5 μm.

[0141] Further, such as Figure 17 As shown, a surface protection layer 24 is prepared. The surface protection layer 24 protects the interdigital electrodes 13 and the wiring layer 23. The material of the surface protection layer 24 includes but is not limited to SiNx material.

[0142] The thickness of the surface protection layer 24 may be in the range of about 5 nm to 20 nm.

[0143] Further, such as Figure 10 As shown, the surface protection layer 24 is etched to form a groove to expose a portion of the surface of the wiring layer 23, and a pad 25 is provided in the groove to achieve electrical connection between the TF-SAW resonator and external components.

[0144] Optionally, based on the above embodiment of the present invention, another embodiment of the present invention further provides a filter, which includes the TF-SAW resonator described in the above embodiment.

[0145] This filter has the same effect as the TF-SAW resonator in the above-mentioned embodiment.

[0146] The above is a detailed introduction to a TF-SAW resonator, a preparation method, and a filter provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

[0147] It should be noted that each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referenced to each other.

[0148] It should also be noted that, in this document, relational terms such as first and second, etc., are used only 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 terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that the process, method, article, or apparatus comprising a series of elements inherent to the elements, or also including elements inherent to these processes, methods, articles, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0149] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform 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 comprises: substrate; a piezoelectric film layer located on one side of the substrate; an interdigitated electrode located on a side of the piezoelectric film layer facing away from the substrate; the interdigitated electrode comprises a bus bar, a sub-bus bar, and an electrode finger, the electrode finger comprising an acoustic portion and an electrical portion, the two ends of the electrical portion being connected to the acoustic portion and the bus bar, respectively; the bus bar comprises a first bus bar and a second bus bar arranged opposite to each other in a first direction, the sub-bus bar comprises a first sub-bus bar and a second sub-bus bar arranged opposite to each other in the first direction; the electrode finger comprises a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar; the first sub-bus bar is located between the first bus bar and the second electrode finger and is connected to the electrical portion of the first electrode finger; the second sub-bus bar is located between the second bus bar and the first electrode finger and is connected to the electrical portion of the second electrode finger; the bus bar and the sub-bus bar extend along a second direction, the length extension direction of the electrode finger is parallel to the first direction, the first direction and the second direction are parallel to the plane of the substrate, and the first direction and the second direction intersect; piston structures located at both ends of the acoustic part; The recess includes a first recess located on a surface of the bus bar facing the sub-bus bar, and / or includes a second recess located on a surface of the sub-bus bar facing the bus bar.

2. The TF-SAW resonator according to claim 1, characterized in that When the recess includes the first recess, in the first direction, the first recess on the first bus bar is arranged correspondingly to the piston structure on the second electrode finger, and the first recess on the second bus bar is arranged correspondingly to the piston structure on the first electrode finger; When the recess includes the second recess, in the first direction, the second recess on the first sub-bus bar is arranged corresponding to the piston structure on the second electrode finger, and the second recess on the second sub-bus bar is arranged corresponding to the piston structure on the first electrode finger; When the recess includes the first recess and the second recess, the first recess and the second recess are arranged in a one-to-one correspondence in the first direction; in the first direction, the first recess on the first bus bar, the second recess on the first sub-bus bar, and the piston structure on the second electrode finger are arranged in a corresponding manner; in the first direction, the first recess on the second bus bar, the second recess on the second sub-bus bar, and the piston structure on the first electrode finger are arranged in a corresponding manner.

3. The TF-SAW resonator according to claim 1, characterized in that The length of the recess in the second direction is L1, and the width of the piston structure in the second direction is L2; Among them, L1=L2.

4. The TF-SAW resonator according to claim 1, characterized in that The width of the recess in the first direction 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 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, characterized in that The length of the first piston structure in the first direction is L4; Wherein, 0.4×λ≤L4≤0.6×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

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

9. The TF-SAW resonator according to claim 1, characterized in that: The maximum width of the busbar in the first direction is L6; Wherein, 3×λ≤L6≤4×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

10. The TF-SAW resonator according to claim 1, characterized in that The maximum width of the sub-busbar in the first direction is L7; Wherein, 0.2×λ≤L7≤0.25×λ; λ is the wavelength of the acoustic wave propagating 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; Wherein, 0.2×λ≤L8≤0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

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

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

14. The TF-SAW resonator according to any one of claims 1 to 13, characterized in that: The TF-SAW resonator further includes: A reflection grid is located at at least one end of the interdigitated electrodes along the second direction.

15. The TF-SAW resonator according to claim 14, characterized in that: The width of the electrode fingers in the reflective grid in the second direction is L11; Wherein, 0.2×λ≤L11≤0.25×λ; λ is the wavelength of the acoustic wave propagating in the TF-SAW resonator.

16. The TF-SAW resonator according to any one of claims 1 to 13, characterized in that: The TF-SAW resonator further includes: At least one dielectric layer is located between the substrate and the piezoelectric 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 method for preparing a TF-SAW resonator, characterized in that: The preparation method of the TF-SAW resonator comprises: providing a substrate; forming a piezoelectric thin film layer on one side of the substrate; An interdigitated electrode is formed on the side of the piezoelectric film layer facing away from the substrate; the interdigitated electrode includes a bus bar, a sub-bus bar and an electrode finger bar, the electrode finger bar includes 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 opposite to each other in a first direction, and the sub-bus bar includes a first sub-bus bar and a second sub-bus bar arranged opposite to each other in the first direction; the electrode finger bar includes 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 electrically connected to the first bus bar. The electrical part of the first electrode finger is connected; the second sub-bus is located between the second bus and the first electrode finger, and is connected to the electrical part of the second electrode finger; the bus and the sub-bus extend along a second direction, the length extension direction of the electrode finger 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; a piston structure is located at both ends of the acoustic part; a depression, the depression includes a first depression located on the surface of the bus bar facing the sub-bus bar, and / or includes a second depression located on the surface of the sub-bus bar facing the bus bar.

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

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